{"document_id": 75488, "context": "The blended slurry was then cast onto a clean current collector (Al foil for the cathode and Cu foil for the anode) and dried at 90 \u00b0C under vacuum overnight.", "question": "What is the cathode?", "answer": "Al foil", "answer_start": 645}
{"document_id": 75488, "context": "The blended slurry was then cast onto a clean current collector (Al foil for the cathode and Cu foil for the anode) and dried at 90 \u00b0C under vacuum overnight. Finally, the obtained electrodes were cut into desired shapes on demand. It should be noted that the electrode mass ratio of cathode/anode is set to about 4, thus achieving the battery balance.", "question": "What is the anode?", "answer": "Cu foil", "answer_start": 673}
{"document_id": 75546, "context": "In conclusion, the SiC/RGO nanocomposite, integrating the synergistic effect of SiC flakes and RGO, was synthesized by an in situ gas\u2013solid fabrication method. Taking advantage of the enhanced photogenerated charge separation, large CO2 adsorption, and numerous exposed active sites, SiC/RGO nanocomposite served as the cathode material for the photo-assisted Li\u2013CO2 battery.", "question": "What is the cathode?", "answer": "SiC/RGO nanocomposite", "answer_start": 284}
{"document_id": 75417, "context": "The calculated diffusion coefficient of Zn2+ was of the order of 10\u22129\u201310\u221210 cm\u22122 s\u22121 (Fig. 4f), which is comparable to that of the reported V-based materials (Table S3\u2020). These results clearly demonstrate that the NV NSs@ACC cathode allows the stable and fast migration of Zn2+, leading to good rate capability.", "question": "What is the cathode?", "answer": "NV NSs@ACC", "answer_start": 2271}
{"document_id": 75422, "context": "Li-ion batteries (LIBs) are expected to have a cell-level specific capacity of >350 W h kg\u22121 by 2025 to meet the market demanded driving range of an electric vehicle (EV). Among the state-of-the-art cathode materials, Ni-rich layered oxides, LiNixCoyAlzO2 (NCA) and LiNixCoyMnzO2 (NCM) with x + y + z = 1 and x \u2267 0.8, have an unbeatable high capacity of \u223c200 mA h g\u22121.", "question": "What is the cathode?", "answer": "Ni-rich layered oxides, LiNixCoyAlzO2 (NCA) and LiNixCoyMnzO2 (NCM)", "answer_start": 242}
{"document_id": 75432, "context": "Mg-doped P2-NMM10 and Zn-doped P2-NMZ10 cathode materials are synthesized by a solid state method, whose P2-type layered structures are confirmed by X-ray diffraction (XRD) (Fig. S1\u2020 and a summary of the crystallographic data is given in Tables S1\u2013S4\u2020). Their compositions are verified by energy dispersive X-ray spectroscopy (EDS) (Fig. S2\u2020), showing that all the dopants are successfully introduced into the bulk materials and uniformly distributed.", "question": "What is the cathode?", "answer": "Mg-doped P2-NMM10 and Zn-doped P2-NMZ10", "answer_start": 120}
{"document_id": 75443, "context": "Li and co-authors applied PTCDA-derived polymer P10 as the anode for aqueous K-ion batteries. Saturated solutions of K2SO4 (\u223c0.69 M) or KNO3 (\u223c3.75 M) were tested as the electrolytes. The potassium nitrate solution enabled better rate capabilities with P10 as the active material, owing to the higher conductivity. Particularly, \u223c90 mA h g\u22121 was delivered at 5.4 A g\u22121, which was about 70% of the value achieved at 0.36 A g\u22121. A full cell with the potassium hexacyanoferrate cathode had an energy density of 24.2 W h kg\u22121 (per mass of both electrodes), could reach a high power of 2.08 kW kg\u22121, and retained 74% of the capacity after 300 cycles.", "question": "What's the cathode?", "answer": "potassium hexacyanoferrate", "answer_start": 448}
{"document_id": 75443, "context": "Li and co-authors applied PTCDA-derived polymer P10 as the anode for aqueous K-ion batteries. Saturated solutions of K2SO4 (\u223c0.69 M) or KNO3 (\u223c3.75 M) were tested as the electrolytes. The potassium nitrate solution enabled better rate capabilities with P10 as the active material, owing to the higher conductivity. Particularly, \u223c90 mA h g\u22121 was delivered at 5.4 A g\u22121, which was about 70% of the value achieved at 0.36 A g\u22121. A full cell with the potassium hexacyanoferrate cathode had an energy density of 24.2 W h kg\u22121 (per mass of both electrodes), could reach a high power of 2.08 kW kg\u22121, and retained 74% of the capacity after 300 cycles.", "question": "What's the anode?", "answer": "PTCDA-derived polymer P10", "answer_start": 26}
{"document_id": 75443, "context": "Li and co-authors applied PTCDA-derived polymer P10 as the anode for aqueous K-ion batteries. Saturated solutions of K2SO4 (\u223c0.69 M) or KNO3 (\u223c3.75 M) were tested as the electrolytes. The potassium nitrate solution enabled better rate capabilities with P10 as the active material, owing to the higher conductivity. Particularly, \u223c90 mA h g\u22121 was delivered at 5.4 A g\u22121, which was about 70% of the value achieved at 0.36 A g\u22121. A full cell with the potassium hexacyanoferrate cathode had an energy density of 24.2 W h kg\u22121 (per mass of both electrodes), could reach a high power of 2.08 kW kg\u22121, and retained 74% of the capacity after 300 cycles.", "question": "What's the electrolyte?", "answer": "K2SO4 (\u223c0.69 M) or KNO3 (\u223c3.75 M) ", "answer_start": 117}
{"document_id": 75438, "context": "Electrolytic water splitting in an electrochemical cell can produce both hydrogen and oxygen through the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, respectively. The electrolysis process can be expressed by eqn (1)\u2013(3).", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75438, "context": "Electrolytic water splitting in an electrochemical cell can produce both hydrogen and oxygen through the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, respectively. The electrolysis process can be expressed by eqn (1)\u2013(3).", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75421, "context": "Lithium-ion/sulfur (Li-ion/S) batteries consisting of metallic lithium-free anodes and sulfur cathodes are promising energy storage solutions. Anode prelithiation enables the Li-ion/S battery assembly with the extensively-developed sulfur cathodes. However, it\u2019s very challenging owing to the low lithiation potentials of anode materials (e.g. Al, 0.32 V vs. Li/Li+). Here, a free-standing LiAl alloy anode (c-LiAl) is prepared via an easy-to-implement chemical prelithiation, by using a newly exploited reagent of lithium 9,9-dimethylfluorene (Li-DiMF) with a lower redox potential of 0.22 V vs. Li/Li+. Compared with the LiAl anode prepared by electrochemical prelithiation (e-LiAl) and the lithium metal anode by electrodeposition (e-Li/Cu), the c-LiAl displays a superior cyclability in half cell test and high resistance towards polysulfide or ambient-air corrosion. When paired with a sulfur cathode, the resulting Li-ion/S battery with c-LiAl demonstrates a much better cycling performance than the Li-ion/S battery with e-LiAl and the lithium/sulfur battery with e-Li/Cu.", "question": "What's the cathode?", "answer": "sulfur", "answer_start": 87}
{"document_id": 75421, "context": "Lithium-ion/sulfur (Li-ion/S) batteries consisting of metallic lithium-free anodes and sulfur cathodes are promising energy storage solutions. Anode prelithiation enables the Li-ion/S battery assembly with the extensively-developed sulfur cathodes. However, it\u2019s very challenging owing to the low lithiation potentials of anode materials (e.g. Al, 0.32 V vs. Li/Li+). Here, a free-standing LiAl alloy anode (c-LiAl) is prepared via an easy-to-implement chemical prelithiation, by using a newly exploited reagent of lithium 9,9-dimethylfluorene (Li-DiMF) with a lower redox potential of 0.22 V vs. Li/Li+. Compared with the LiAl anode prepared by electrochemical prelithiation (e-LiAl) and the lithium metal anode by electrodeposition (e-Li/Cu), the c-LiAl displays a superior cyclability in half cell test and high resistance towards polysulfide or ambient-air corrosion. When paired with a sulfur cathode, the resulting Li-ion/S battery with c-LiAl demonstrates a much better cycling performance than the Li-ion/S battery with e-LiAl and the lithium/sulfur battery with e-Li/Cu.", "question": "What's the anode?", "answer": " LiAl alloy", "answer_start": 389}
{"document_id": 75421, "context": "Lithium-ion/sulfur (Li-ion/S) batteries consisting of metallic lithium-free anodes and sulfur cathodes are promising energy storage solutions. Anode prelithiation enables the Li-ion/S battery assembly with the extensively-developed sulfur cathodes. However, it\u2019s very challenging owing to the low lithiation potentials of anode materials (e.g. Al, 0.32 V vs. Li/Li+). Here, a free-standing LiAl alloy anode (c-LiAl) is prepared via an easy-to-implement chemical prelithiation, by using a newly exploited reagent of lithium 9,9-dimethylfluorene (Li-DiMF) with a lower redox potential of 0.22 V vs. Li/Li+. Compared with the LiAl anode prepared by electrochemical prelithiation (e-LiAl) and the lithium metal anode by electrodeposition (e-Li/Cu), the c-LiAl displays a superior cyclability in half cell test and high resistance towards polysulfide or ambient-air corrosion. When paired with a sulfur cathode, the resulting Li-ion/S battery with c-LiAl demonstrates a much better cycling performance than the Li-ion/S battery with e-LiAl and the lithium/sulfur battery with e-Li/Cu.", "question": "What's the anode?", "answer": "LiAl", "answer_start": 623}
{"document_id": 75426, "context": "The data for organic-based anode materials are provided in Table 2. Only a few reports, which were discussed in Section 3.3, were dedicated to aqueous batteries. For this reason, the summary and outlook will be focusing on the non-aqueous systems. As in the case of cathode materials (Section 2.7), we chose several inorganic benchmarks, which showed superior capacities, rate capabilities or cycling stability. These benchmarks include graphite, porous carbon (p. C), N-doped carbon (N-d. C), bismuth, antimony, iron disulfide and red phosphorous.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75426, "context": "The data for organic-based anode materials are provided in Table 2. Only a few reports, which were discussed in Section 3.3, were dedicated to aqueous batteries. For this reason, the summary and outlook will be focusing on the non-aqueous systems. As in the case of cathode materials (Section 2.7), we chose several inorganic benchmarks, which showed superior capacities, rate capabilities or cycling stability. These benchmarks include graphite, porous carbon (p. C), N-doped carbon (N-d. C), bismuth, antimony, iron disulfide and red phosphorous.", "question": "What's the anode?", "answer": "organic-based", "answer_start": 13}
{"document_id": 75436, "context": "We explore a novel ether aided superconcentrated ionic liquid electrolyte; a combination of ionic liquid, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI) and ether solvent, 1,2 dimethoxy ethane (DME) with 3.2 mol/kg LiFSI salt, which offers an alternative ion-transport mechanism and improves the overall fluidity of the electrolyte. The molecular dynamics (MD) study reveals that the coordination environment of lithium in the ether aided ionic liquid system offers a coexistence of both the ether DME and FSI anion simultaneously and the absence of \u2018free\u2019, uncoordinated DME solvent. These structures lead to very fast kinetics and improved current density for lithium deposition-dissolution processes. Hence the electrolyte is used in a lithium metal battery against a high mass loading (~12 mg/cm2) LFP cathode which was cycled at a relatively high current rate of 1mA/cm2 for 350 cycles without capacity fading and offered an overall coulombic efficiency of >99.8 %. Additionally, the rate performance demonstrated that this electrolyte is capable of passing current density as high as 7mA/cm2 without any electrolytic decomposition and offers a superior capacity retention. We have also demonstrated an \u2018anode free\u2019 LFP-Cu cell which was cycled over 50 cycles and achieved an average coulombic efficiency of 98.36%. The coordination chemistry and (electro)chemical understanding as well as the excellent cycling stability collectively leads toward a breakthrough in realizing the practical applicability of this ether aided ionic liquid electrolytes in lithium metal battery applications, while delivering high energy density in a prototype cell.", "question": "What's the cathode?", "answer": "LFP", "answer_start": 823}
{"document_id": 75436, "context": "We explore a novel ether aided superconcentrated ionic liquid electrolyte; a combination of ionic liquid, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI) and ether solvent, 1,2 dimethoxy ethane (DME) with 3.2 mol/kg LiFSI salt, which offers an alternative ion-transport mechanism and improves the overall fluidity of the electrolyte. The molecular dynamics (MD) study reveals that the coordination environment of lithium in the ether aided ionic liquid system offers a coexistence of both the ether DME and FSI anion simultaneously and the absence of \u2018free\u2019, uncoordinated DME solvent. These structures lead to very fast kinetics and improved current density for lithium deposition-dissolution processes. Hence the electrolyte is used in a lithium metal battery against a high mass loading (~12 mg/cm2) LFP cathode which was cycled at a relatively high current rate of 1mA/cm2 for 350 cycles without capacity fading and offered an overall coulombic efficiency of >99.8 %. Additionally, the rate performance demonstrated that this electrolyte is capable of passing current density as high as 7mA/cm2 without any electrolytic decomposition and offers a superior capacity retention. We have also demonstrated an \u2018anode free\u2019 LFP-Cu cell which was cycled over 50 cycles and achieved an average coulombic efficiency of 98.36%. The coordination chemistry and (electro)chemical understanding as well as the excellent cycling stability collectively leads toward a breakthrough in realizing the practical applicability of this ether aided ionic liquid electrolytes in lithium metal battery applications, while delivering high energy density in a prototype cell.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75441, "context": "2.1.5 Electrochemical performance measurements. The electrochemical performances of an individual electrode, Fe-intercalated ML Ti3C2Tx anode, and graphite cathode were examined in a three-electrode system in an Ar-filled glove box with O2 and H2O levels below 0.1 ppm, using platinum foil as the counter electrode and a silver-ion electrode as the reference electrode. For full device testing, a two-electrode electrolyzer was employed, with an Fe-intercalated ML Ti3C2Tx anode and graphite cathode. The electrolyte was 1 M EMIm+[PF6]\u2212 ionic liquid (1.2 mL) dissolved in PC (1.5 mL) and EMC (3 mL) solvent. CV and GCD experiments were performed using a CHI660E electrochemical workstation (Chenhua, China). EIS was conducted at open-circuit potential, with an amplitude of 5 mV and frequencies ranging from 10 mHz to 100 kHz.", "question": "What's the cathode?", "answer": "graphite", "answer_start": 147}
{"document_id": 75441, "context": "2.1.5 Electrochemical performance measurements. The electrochemical performances of an individual electrode, Fe-intercalated ML Ti3C2Tx anode, and graphite cathode were examined in a three-electrode system in an Ar-filled glove box with O2 and H2O levels below 0.1 ppm, using platinum foil as the counter electrode and a silver-ion electrode as the reference electrode. For full device testing, a two-electrode electrolyzer was employed, with an Fe-intercalated ML Ti3C2Tx anode and graphite cathode. The electrolyte was 1 M EMIm+[PF6]\u2212 ionic liquid (1.2 mL) dissolved in PC (1.5 mL) and EMC (3 mL) solvent. CV and GCD experiments were performed using a CHI660E electrochemical workstation (Chenhua, China). EIS was conducted at open-circuit potential, with an amplitude of 5 mV and frequencies ranging from 10 mHz to 100 kHz.", "question": "What's the anode?", "answer": "Fe-intercalated ML Ti3C2Tx", "answer_start": 109}
{"document_id": 75441, "context": "2.1.5 Electrochemical performance measurements. The electrochemical performances of an individual electrode, Fe-intercalated ML Ti3C2Tx anode, and graphite cathode were examined in a three-electrode system in an Ar-filled glove box with O2 and H2O levels below 0.1 ppm, using platinum foil as the counter electrode and a silver-ion electrode as the reference electrode. For full device testing, a two-electrode electrolyzer was employed, with an Fe-intercalated ML Ti3C2Tx anode and graphite cathode. The electrolyte was 1 M EMIm+[PF6]\u2212 ionic liquid (1.2 mL) dissolved in PC (1.5 mL) and EMC (3 mL) solvent. CV and GCD experiments were performed using a CHI660E electrochemical workstation (Chenhua, China). EIS was conducted at open-circuit potential, with an amplitude of 5 mV and frequencies ranging from 10 mHz to 100 kHz.", "question": "What's the cathode?", "answer": "graphite", "answer_start": 483}
{"document_id": 75419, "context": "The increased environmental hazards from the use of carbon-emitting fuels and the rapid depletion of conventional fossil fuels have triggered the research community to find alternatives to fossil-fuel-based technologies. In many innovative approaches to address these challenges, electrocatalytic water splitting driven by a renewable energy input to produce clean H2 has been widely viewed as a promising strategy as hydrogen is produced from renewable sources (such as solar and wind energy), which can be stored, transported and consumed without generating any carbon-based byproducts. Electrolysers are a crucial factor for water electrolysis. Currently, great efforts are being made to develop new electrocatalysts with high efficiency for overall water splitting. In addition to the advancement of electrocatalysts, another equally important aspect of water electrolysis is the development of novel electrolyzer design. The conventional cell design of a alkaline water electrolyser is illustrated in Scheme 1a. Both electrodes are dipped into an aqueous alkaline electrolyte with a separator (ion exchange membrane or porous diaphragm) between them. H2 and O2 are produced on the electrodes via two half-cell reactions: the hydrogen evolution reaction (HER), and the oxygen evolution reaction (OER). In the lab, these electrolysers are used directly, while in industry, these electrolysers are used in stacks to scale-up H2 production. For electrolysers, major costs are due to the fabrication and material for the three main components: anodes, cathodes and separators. The existence of a separator not only increases the cost of the electrolyser, but also induces extra overpotentials for water splitting. A new electrolyser with a simple, condensed, membrane-free design is highly desired since it not only requires lower overpotentials, but also needs smaller areas and fewer materials, which reduces the overall cost of the electrolyser cells and promotes the electrochemical water splitting.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75419, "context": "The increased environmental hazards from the use of carbon-emitting fuels and the rapid depletion of conventional fossil fuels have triggered the research community to find alternatives to fossil-fuel-based technologies. In many innovative approaches to address these challenges, electrocatalytic water splitting driven by a renewable energy input to produce clean H2 has been widely viewed as a promising strategy as hydrogen is produced from renewable sources (such as solar and wind energy), which can be stored, transported and consumed without generating any carbon-based byproducts. Electrolysers are a crucial factor for water electrolysis. Currently, great efforts are being made to develop new electrocatalysts with high efficiency for overall water splitting. In addition to the advancement of electrocatalysts, another equally important aspect of water electrolysis is the development of novel electrolyzer design. The conventional cell design of a alkaline water electrolyser is illustrated in Scheme 1a. Both electrodes are dipped into an aqueous alkaline electrolyte with a separator (ion exchange membrane or porous diaphragm) between them. H2 and O2 are produced on the electrodes via two half-cell reactions: the hydrogen evolution reaction (HER), and the oxygen evolution reaction (OER). In the lab, these electrolysers are used directly, while in industry, these electrolysers are used in stacks to scale-up H2 production. For electrolysers, major costs are due to the fabrication and material for the three main components: anodes, cathodes and separators. The existence of a separator not only increases the cost of the electrolyser, but also induces extra overpotentials for water splitting. A new electrolyser with a simple, condensed, membrane-free design is highly desired since it not only requires lower overpotentials, but also needs smaller areas and fewer materials, which reduces the overall cost of the electrolyser cells and promotes the electrochemical water splitting.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75424, "context": "One should note that in this first demonstration of the nanomesh-based cathodes, the thickness of the electrodes of few micrometres remains insufficient for practical application in Li-ion batteries that require thicker electrodes, in the range of tens of micrometres. Thus, the next natural step is the realization of thicker electrodes, which should be feasible given the up-scalable character of their electro-fabrication. Also, the cracks observed in the electrodes after thermal activation of LMO could somewhat affect the performance and integration of the electrodes in batteries. Such cracking originates from the expanding volume of the drop-cast LiOH during its solidification, the thermomechanical stress exerted on the nanowires during the relatively rapid ramp-up phase of annealing or the capillary forces acting on the nanomesh structure during the final drying. Further studies could address this by changing the lithium precursor to a gaseous one, pre-annealing of the nanowires to relieve the internal stress, lowering the heating rate during the conversion or optimization of drying (e.g. through supercritical drying). Furthermore, the highly nanostructured character of our cathodes comes at an expense of a lower thermal budget during the integration of the current collector with the active material, a sloping potential during the discharge and an increased rate of side-reactions. Although compared to other 3D cathodes the nanomesh cathode shows a similar cycling stability (78% of initial capacity after 50 cycles at 1.2C), it will need to be further increased for practical device applications. A detailed post-mortem analysis of the electrodes could be helpful in choosing an appropriate route for mitigating capacity fading. The potential methods include the application of thin protective coatings (such as TiO2) or integration of the electrode with a solid electrolyte (which is, anyway, inherent for application in microbatteries). A candidate electrolyte could be one of the highly-conductive solid composite electrolytes which are obtained through controlled hydrolysis of lithiated silicon alkoxides from the liquid phase and, thus, could well penetrate and impregnate the porous nanowire electrode. Also, the active electrode material could be changed to a compound with a higher cycling stability than LixMnO2, provided it can be synthesized at sufficiently low temperatures to avoid oxidation of the current collector. This could be done by, for example, electrodeposition from eutectic melts reported by Zhang et al., which was demonstrated to produce dense, high quality LiCoO2 and highly stable LiMn2O4 3D coatings at low temperatures of 260\u2013300 \u00b0C. Contrary to the alternative low temperature sol\u2013gel or solvothermal syntheses, molten-salt electrolysis avoids the excessive gas evolution and pressure build-up which can be detrimental to the nanoporous electrodes. Perhaps, such electrodeposition could also be extended in the future to other attractive cathode materials, allowing integration of the nanomesh with e.g. high voltage lithium nickel manganese cobalt oxides (NMC).", "question": "What's the cathode?", "answer": " nanomesh-based", "answer_start": 55}
{"document_id": 75429, "context": "For full cell testing, sulfur\u2013carbon composite cathodes were used. It is well known that S, lithium disulfide and other reaction intermediates have poor electronic conductivity. To improve this, S nanoparticles were impregnated into a nitrogen doped carbon matrix (from now on labelled \u2018S/NC\u2019); a detailed account on the synthesis of the cathode was given in our previous report. The carbon composite matrix with good electronic conductivity and a high surface area (700 m2 g\u22121) contained graphene and multiwall carbon nanotubes in an equal weight ratio. The morphology of the cathode material is illustrated in the SEM image shown in Fig. S4.\u2020 Further, thermo-gravimetric analysis (TGA) shows a S loading of \u223c55 wt% in the S/NC cathode (Fig. S5, ESI\u2020).", "question": "What's the cathode?", "answer": "sulfur\u2013carbon composite", "answer_start": 23}
{"document_id": 75429, "context": "For full cell testing, sulfur\u2013carbon composite cathodes were used. It is well known that S, lithium disulfide and other reaction intermediates have poor electronic conductivity. To improve this, S nanoparticles were impregnated into a nitrogen doped carbon matrix (from now on labelled \u2018S/NC\u2019); a detailed account on the synthesis of the cathode was given in our previous report. The carbon composite matrix with good electronic conductivity and a high surface area (700 m2 g\u22121) contained graphene and multiwall carbon nanotubes in an equal weight ratio. The morphology of the cathode material is illustrated in the SEM image shown in Fig. S4.\u2020 Further, thermo-gravimetric analysis (TGA) shows a S loading of \u223c55 wt% in the S/NC cathode (Fig. S5, ESI\u2020).", "question": "What's the cathode?", "answer": " S/NC", "answer_start": 723}
{"document_id": 75434, "context": "Recently, potassium manganese oxides (KMOs) have gained more attention as positive materials due to their high operating voltage, high conductivity and controllable flexible interlayer spacing, which are beneficial for K+ ion diffusion and offer more ion intercalation channels over the whole exposed surface. For example, Kim et al. reported a P3-type layered structure of K0.5MnO2 as the cathode material for non-aqueous potassium-ion batteries, which exhibited a specific capacity of \u2248100 mA h g\u22121 with good capacity retention. Zhao et al. synthesized AlF3-coated K1.39Mn3O6 microspheres that showed a highly reversible capacity of 110 mA h g\u22121 at 10 mA g\u22121, excellent cycling stability and rate capability. Xia et al. prepared the high K-content K0.77MnO2\u00b70.23H2O for high-performance non-aqueous K-ion batteries with 134 mA h g\u22121 at a current density of 100 mA g\u22121.", "question": "What's the cathode?", "answer": "K0.5MnO2", "answer_start": 374}
{"document_id": 75439, "context": "The data for organic-based cathode materials are summarized in Table 1. All these compounds were reported for non-aqueous batteries, which should be mainly due to the mismatch between their working potentials and water stability voltage window. Some n-type materials, such as quinones or aromatic imides, can operate without decomposition of water, especially with highly concentrated electrolytes. However, their working potentials are close to the onset of the hydrogen evolution reaction, which makes them more suitable for anodes rather than for cathodes (see Section 3.3). There are several reports on aromatic amines and nitroxyl radicals as cathodes for aqueous Li-, Na-, Zn- and ammonium-based cells. It might be expected that similar K-based aqueous dual-ion batteries will become successful in the future.", "question": "What's the cathode?", "answer": "organic-based", "answer_start": 13}
{"document_id": 75439, "context": "The data for organic-based cathode materials are summarized in Table 1. All these compounds were reported for non-aqueous batteries, which should be mainly due to the mismatch between their working potentials and water stability voltage window. Some n-type materials, such as quinones or aromatic imides, can operate without decomposition of water, especially with highly concentrated electrolytes. However, their working potentials are close to the onset of the hydrogen evolution reaction, which makes them more suitable for anodes rather than for cathodes (see Section 3.3). There are several reports on aromatic amines and nitroxyl radicals as cathodes for aqueous Li-, Na-, Zn- and ammonium-based cells. It might be expected that similar K-based aqueous dual-ion batteries will become successful in the future.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75444, "context": "When cycled at 4.5 V, as shown in Fig. 6(a), P2-NMZ10 has 68% capacity retention after 200 cycles, while P2-NMM10 only has 51% capacity retention after 200 cycles, indicating that the Zn-doped sample possesses superior cyclability. Our detailed structural analysis reveals that the dopant precipitates in P2-NMZ10 samples are more stable upon continuous cycling, while the precipitates in P2-NMM10 samples are not stable. As shown in Fig. 6(b\u2013d), the morphology of Mg-enriched precipitates changes obviously with increasing cycle numbers, especially from 100 cycles to 200 cycles, and finally high density intragranular cracks and nano-voids (revealed in Li-rich layered cathodes ) are developed after 200 cycles. Note that bulk degradations initiate from the grain interior after prolonged cycles (see more examples in Fig. S11(a and b)\u2020). For the P2-NMZ10 sample, the precipitates are quite stable once formed. As illustrated in Fig. 6(e\u2013g), the lamellar morphology and the density of the precipitates remain similar up to 200 cycles. More P2-NMZ10 examples are shown in Fig. S11(c and d).\u2020 The stabilized structure enables the stable cyclability of P2-NMZ10. Therefore, a good dopant should form high-density stable nano-precipitates so that the bulk structure does not degrade upon prolonged cycling.", "question": "What's the cathode?", "answer": "Li-rich layered", "answer_start": 655}
{"document_id": 75425, "context": "A very rapid increase in separation between the \u2018charge-averaged\u2019 discharge and charge voltages, within the first few cycles (i.e., \u223c10 cycles), can be observed for the \u2018no\u2019 Ti-containing Na-TM-oxide (i.e., \u20180.5 Mn/0 Ti\u2019) (see Fig. 4a and b). This is a direct reflection of the rapid increment in corresponding voltage hysteresis (see Fig. 3a), and also ties-up with the rapid capacity fading observed in these very first 10 cycles (see Fig. 3d). By contrast, the changes in \u2018charge-averaged\u2019 voltages in case of the fully Ti-substituted Na-TM-oxide are insignificant, even up to the entire duration of galvanostatic cycling (viz., 100 cycles). Interestingly, despite the notable difference in behavior between the \u20180.5 Mn/0 Ti\u2019 and \u20180 Mn/0.5 Ti\u2019 Na-TM-oxide cathodes in the context of variations of the \u2018charge-averaged\u2019 discharge and charge voltages during cycling, the corresponding net-average voltages (viz., average of Vdischarge and Vcharge) do not appear to change during cycling in both the cases, with the net-average voltage for the fully Ti-substituted counterpart being consistently greater than that for the \u2018control\u2019 Na-TM-oxide cathode by \u223c0.25 V. A decrease and increase in Vdischarge and Vcharge, respectively, during electrochemical cycling, are primarily manifestations of build-up of electrode/cell impedance (as also suggested by Jung et al.), whereas any notable variation of the net-average voltage during cycling (as not observed here) is more likely to be a manifestation of irreversible change in the structure (even if just at the surface) of the concerned electrode material. Accordingly, the above observations (viz., Fig. 4) indicate that replacement of Mn-ions by Ti-ions in the Na-TM-oxide cathode considerably suppresses the build-up of electrode/cell impedance upon electrochemical cycling. These will be discussed in more detail in the next two sections.", "question": "What's the cathode?", "answer": "\u20180.5 Mn/0 Ti\u2019 and \u20180 Mn/0.5 Ti\u2019 Na-TM-oxide", "answer_start": 715}
{"document_id": 75435, "context": "In this work, we use focused ion beam-scanning electron microscope (FIB-SEM)-based tomography with sub-100 nm spatial resolution to visualize and quantify the loss of mechanical contact in an SSB cathode composite after cycling. Quantitative analysis of the microstructural evolution and interface separation reveals a correlation between the capacity fade and the loss of physical contact between the cathode particles and solid electrolyte upon cycling.", "question": "What's the cathode?", "answer": "SSB", "answer_start": 192}
{"document_id": 75440, "context": "\u2022 A high sulfur loading is essential to produce practical Li\u2013S batteries. The metal sulfides for the design of 3D free-standing and sandwich-type cathodes contribute to a high sulfur loading without sacrificing rate capacities and cycling stability.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75445, "context": "The working electrode was composed of carbon paper, the as-prepared electrocatalysts (70 wt%), super P (20 wt%) and a PVDF binder (10 wt%). The mass loading of the electrocatalysts on the carbon paper was 0.6\u20130.8 mg cm\u22122. The electrolyte was 1 M lithium bis (trifluoromethane) sulfonimide, LiTFSI, in dimethyl sulfoxide (DMSO). 2032-type coin LOBs, which included a lithium metal anode (\u00d8 = 15 mm), a glass-fiber separator (GFC, Whatman, \u00d8 = 19 mm) impregnated with an electrolyte, and a well-prepared cathode (\u00d8 = 14 mm), were assembled in a glove box filled with high purity Ar. The electrochemical performance of the assembled LOBs was measured in a sealed home-made container filled with high purity O2. The galvanostatic discharge\u2013charge tests were carried out on a LAND BT 2000 battery testing system. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted on a CHI 604B electrochemical workstation. Before each electrochemical test, the as-assembled LOBs were first equilibrated for several hours. In this work, all the current densities and specific capacities of LOBs were normalized by the actual mass loading of the active materials.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75445, "context": "The working electrode was composed of carbon paper, the as-prepared electrocatalysts (70 wt%), super P (20 wt%) and a PVDF binder (10 wt%). The mass loading of the electrocatalysts on the carbon paper was 0.6\u20130.8 mg cm\u22122. The electrolyte was 1 M lithium bis (trifluoromethane) sulfonimide, LiTFSI, in dimethyl sulfoxide (DMSO). 2032-type coin LOBs, which included a lithium metal anode (\u00d8 = 15 mm), a glass-fiber separator (GFC, Whatman, \u00d8 = 19 mm) impregnated with an electrolyte, and a well-prepared cathode (\u00d8 = 14 mm), were assembled in a glove box filled with high purity Ar. The electrochemical performance of the assembled LOBs was measured in a sealed home-made container filled with high purity O2. The galvanostatic discharge\u2013charge tests were carried out on a LAND BT 2000 battery testing system. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted on a CHI 604B electrochemical workstation. Before each electrochemical test, the as-assembled LOBs were first equilibrated for several hours. In this work, all the current densities and specific capacities of LOBs were normalized by the actual mass loading of the active materials.", "question": "What's the anode?", "answer": "lithium metal", "answer_start": 366}
{"document_id": 75450, "context": "In this review, we have provided a comprehensive overview of the design, synthesis, and application of metal sulfides in rechargeable Li\u2013S batteries. We aimed to summarize important concepts to boost the practical development of high-energy-density Li\u2013S batteries. As a promising polar substrate, metal sulfides have considerable benefits, including a moderately strong affinity for active sulfide binding, high electronic conductivity, the ability to modulate redox reaction kinetics, and a high activity capacity contribution. Through the use of metal sulfides, great progress has been made in improving sulfur cathodes, design of interlayers, modification of separators, and protection of lithium anodes. Despite these achievements, challenges remain in terms of developing affordable large-scale synthesis techniques, elucidating an in-depth mechanism of binding LiPSs, enhancing the rationality and reliability of theoretical simulations, and building stable high-energy-density Li\u2013S batteries over routine LIBs. We hope that this review will inspire greater interest in the use of metal sulfides and other related materials with similar effects as polar substrates for the exploitation of advanced Li\u2013S batteries.", "question": "What's the cathode?", "answer": "sulfur ", "answer_start": 606}
{"document_id": 75450, "context": "In this review, we have provided a comprehensive overview of the design, synthesis, and application of metal sulfides in rechargeable Li\u2013S batteries. We aimed to summarize important concepts to boost the practical development of high-energy-density Li\u2013S batteries. As a promising polar substrate, metal sulfides have considerable benefits, including a moderately strong affinity for active sulfide binding, high electronic conductivity, the ability to modulate redox reaction kinetics, and a high activity capacity contribution. Through the use of metal sulfides, great progress has been made in improving sulfur cathodes, design of interlayers, modification of separators, and protection of lithium anodes. Despite these achievements, challenges remain in terms of developing affordable large-scale synthesis techniques, elucidating an in-depth mechanism of binding LiPSs, enhancing the rationality and reliability of theoretical simulations, and building stable high-energy-density Li\u2013S batteries over routine LIBs. We hope that this review will inspire greater interest in the use of metal sulfides and other related materials with similar effects as polar substrates for the exploitation of advanced Li\u2013S batteries.", "question": "What's the anode?", "answer": "lithium ", "answer_start": 692}
{"document_id": 75455, "context": "Long cyclic lifespan under high-current density is an important factor to assess the possibility of practical application. Fig. 3e presents the GCD result at a high current density of 2.0 A g\u22121. Approximately 85% retention of the capacity over 1000 cycles (the initial capacity was 183 mA h g\u22121) and CEs of the NV NSs@ACC electrode more than 99% were measured, demonstrating the outstanding stability and efficacy of rapid electron transfer during the charge/discharge processes. By contrast, the NV-ACC electrode only shows a capacity of 45 mA h g\u22121 with obvious long-time active phenomenon (Fig. S3c\u2020). The worsening performance of the NV-ACC electrode is mainly caused by the loose binding force between the active materials and the ACC substrate as well as the non-active binder, resulting in low conductivity and instability. This kind of traditional electrode needs more cycles to activate the cathode materials, which could be attributed to the inefficient electronic and mechanical contact between the active materials and the electrolyte, compared with the binder-free 2D ultrathin nanosheets grown on the ACC. To better verify this hypothesis, electrochemical impedance spectroscopy (EIS) was employed to investigate the ion transport property within the NV NSs@ACC electrode, as shown in Fig. S4a,\u2020 where a lower charge-transfer resistance (Rct) can be clearly observed compared to that of NV-ACC.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75448, "context": "As a supplementary experiment to further confirm this advantageous effect of the DETA CB powders, we fabricated a coin-type (2032R) half cell (printed LCO cathode/liquid electrolyte (1 M LiPF6 in EC/PC (1/1 (v/v)))-filled polyethylene separator/Li metal anode) and investigated its electrochemical performance. The cell containing the DETA CB powders showed the higher discharge rate capability compared to its counterpart containing the pristine CB powders at a fixed charge current density of 0.1C (Fig. S4B\u2020). Moreover, the cell with the DETA CB powders exhibited the higher charge rate capability at a fixed discharge current density of 0.1C (Fig. S4C\u2020). It should be noted that this superior charge rate capability enabled by the DETA CB powders is expected to improve the storage efficiency of the electric energy generated by the cSiPV module.", "question": "What's the cathode?", "answer": "LCO ", "answer_start": 151}
{"document_id": 75448, "context": "As a supplementary experiment to further confirm this advantageous effect of the DETA CB powders, we fabricated a coin-type (2032R) half cell (printed LCO cathode/liquid electrolyte (1 M LiPF6 in EC/PC (1/1 (v/v)))-filled polyethylene separator/Li metal anode) and investigated its electrochemical performance. The cell containing the DETA CB powders showed the higher discharge rate capability compared to its counterpart containing the pristine CB powders at a fixed charge current density of 0.1C (Fig. S4B\u2020). Moreover, the cell with the DETA CB powders exhibited the higher charge rate capability at a fixed discharge current density of 0.1C (Fig. S4C\u2020). It should be noted that this superior charge rate capability enabled by the DETA CB powders is expected to improve the storage efficiency of the electric energy generated by the cSiPV module.", "question": "What's the electrolyte?", "answer": "1 M LiPF6 in EC/PC (1/1 (v/v))", "answer_start": 183}
{"document_id": 75459, "context": "However, because of the larger sodium ionic radius (rNa+ 1.02 \u00c5 vs. rLi+ 0.76 \u00c5), it is necessary to explore suitable cathode materials and modification methods that could accommodate sufficient sodium ions as well as ensure reversible and fast Na+ insertion/extraction. Various types of cathode materials have been proposed, including layered transition-metal oxides (NaxMO2), Prussian blue analogues (PBAs, NaxMy[Fe(CN)6]), polyanion-type compounds, and organic compounds. Due to the strong P\u2013O covalent bond of the PO43\u2212 group, combined with the high electronegativity of the fluoride anion (F\u2212), fluorophosphate-based polyanion compounds generally have robust crystal frameworks and tunable high redox potentials, which makes them get more attention.", "question": "What's the cathode?", "answer": "layered transition-metal oxides (NaxMO2), Prussian blue analogues (PBAs, NaxMy[Fe(CN)6]), polyanion-type compounds, and organic compounds", "answer_start": 336}
{"document_id": 75464, "context": "Firstly, the effect of the KMnO4 concentration on the MnO2 loading and the capacity of the battery was studied. As shown in Fig. 3e, the loading of MnO2 on the electrode gradually increases with the increase of KMnO4 concentration. When the concentration of KMnO4 is 0.1 mM, a low MnO2 loading of 4.9 mg cm\u22123 (weight percentage of 21.1%) is obtained. And the capacity of the corresponding battery can be as high as 369.7 mA h g\u22121 (based on the mass of the active material of MnO2), superior to that of most of the earlier reported Zn\u2013MnO2 batteries and aqueous zinc batteries (see Table S1\u2020), such as Zn\u2013MnO2 batteries (225 mA h g\u22121), Zn\u2013ZnMn2O4 batteries (150 mA h g\u22121), Zn\u2013PTO batteries (336 mA h g\u22121), Zn\u2013NiCo2O4 batteries (183.1 mA h g\u22121), Zn\u2013MoS2 batteries (202.6 mA h g\u22121), Ni\u2013Zn batteries (265 mA h g\u22121), and Zn\u2013V2O5@PEDOT batteries (360 mA h g\u22121). When the concentration of KMnO4 increases to 10 mM, the mass loading of MnO2 reaches 51.0 mg cm\u22123 (weight percentage of 79.1%), and the corresponding capacity remains at 306.7 mA h g\u22121. Meanwhile, the volumetric capacity of the battery increases accordingly at the beginning, and reaches its highest value (15.6 mA h cm\u22123) when the concentration of KMnO4 is about 10 mM, which is chosen as the optimal concentration for the preparation of cathode materials. Notably, a high loading of MnO2 seems to have a negligible effect on the ion diffusion as elucidated from the Nyquist plots in Fig. S9.\u2020 The linear slopes for the two electrodes are nearly the same, indicative of their similar ion diffusion resistance. High mass loading and high volumetric capacity are desirable in energy storage devices because of the advantages in maximizing the packing density of the electrode materials while lowering the manufacturing cost by reducing the number of inactive material layers.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75468, "context": "In voltage research, the advantages of cathode exfoliation and anode exfoliation can be combined by using the voltage of the changing direction, and the process of electrolyte intercalation and gas expansion can be brought into full play.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75468, "context": "In voltage research, the advantages of cathode exfoliation and anode exfoliation can be combined by using the voltage of the changing direction, and the process of electrolyte intercalation and gas expansion can be brought into full play.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75447, "context": "The vanadium loss of the cathode is measured using inductive coupled plasma optical emission spectroscopy (ICP OES) after 7, 20 and 40 cycles in the discharged state as it is difficult to accurately quantify the small amount of dissolved vanadium after the first cycle. It can be seen from Fig. 9 that a considerable amount of V is lost from the cathode. The extent of vanadium dissolution is roughly proportional to the upper potential limit used in the cycling, which indicates a correlation between the V loss and the anionic redox activity. The vanadium dissolution allows the V4+ ions and partially oxidized oxygen ions (e.g., O\u2212 ions, peroxides and superoxides) to remain in the structure upon the reinsertion of Li+ based on the charge neutrality. The formation of anionic redox species and its reversibility are closely linked to the vanadium dissolution, although their causalities remain unclear (i.e., whether the vanadium dissolution leads to the formation of anionic redox species and reduce its reversibility, or vice versa). We note that a lack of causality is also possible as they may occur simultaneously to stabilize each other due to their opposite contribution to the net charge.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75451, "context": "Areal capacities for organic-based cathodes range from \u223c0.07 to \u223c2 mA h cm\u22122 (Chart 1d). As in the case with the electrode composition, no optimization of the mass loading is typically performed. For PTCDA 9, where such optimization took place, record high areal capacity was demonstrated.", "question": "What's the cathode?", "answer": "organic-based", "answer_start": 21}
{"document_id": 75461, "context": "In order to get rid of templates, many efforts have been attempted. CP nanowire electrochemically polymerized and assembled onto two biased electrodes (anode and cathode) immersed in aqueous monomer solutions. The essence of this method is an electrode-wire-electrode or electrode-wire-target assembly. For instance, CP nanowires are prepared by an electro-deposition within channels between two electrodes on the surface of silicon wafers. By using this way, Chouvy et al. prepared oriented PPy nanowires and found the diameter and the length of the nanowires can be increased when the solution contained a high concentration of weak-acid anions and a low concentration of non-acidic anions. Since electrochemical polymerization is a shared and controlled method for preparing CPs and their nanostructures, electro-deposition within channels between two electrodes has received attention in fabricating molecule devices.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75461, "context": "In order to get rid of templates, many efforts have been attempted. CP nanowire electrochemically polymerized and assembled onto two biased electrodes (anode and cathode) immersed in aqueous monomer solutions. The essence of this method is an electrode-wire-electrode or electrode-wire-target assembly. For instance, CP nanowires are prepared by an electro-deposition within channels between two electrodes on the surface of silicon wafers. By using this way, Chouvy et al. prepared oriented PPy nanowires and found the diameter and the length of the nanowires can be increased when the solution contained a high concentration of weak-acid anions and a low concentration of non-acidic anions. Since electrochemical polymerization is a shared and controlled method for preparing CPs and their nanostructures, electro-deposition within channels between two electrodes has received attention in fabricating molecule devices.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75465, "context": "Herein, with the aid of an electrochemistry-driven method, Fe ions were pre-intercalated into multilayered Ti3C2Tx (ML Ti3C2Tx) using cyclic voltammetry (CV) technology. Systemic characterization of the interlayer environment was conducted. The location of Fe ions was analyzed, combined with DFT simulations. The EMIm+ storage abilities of the Fe pre-intercalated MXene were confirmed using a dual-ion energy storage system including a graphite cathode. Meanwhile, the intercalation behavior of EMIm+ was studied via ex situ XRD and XPS. The complex relationship between the interlayer, EMIm+, and confined Fe ions was investigated.", "question": "What's the cathode?", "answer": "graphite", "answer_start": 437}
{"document_id": 75454, "context": "Spherical [Ni0.5Mn0.5](OH)2 precursors were synthesized by the co-precipitation method. Stoichiometric amounts of NiSO4\u00b76H2O and MnSO4\u00b7H2O (Samchun Chemical, Korea) were used as starting materials for [Ni0.5Mn0.5](OH)2. The metal solution concentration (2 mol L\u22121 for the metal solution), pH (\u223c11.0), temperature (45 \u00b0C), and stirring speed of the mixture in the batch-type reactor were carefully controlled. At the same time, aqueous NaOH (Samchun, Korea; NaOH/transition metal molar ratio = 2:1) and aqueous NH4OH (Junsei, Japan; NH4OH/transition metal molar ratio = 1.1:1) as chelating agents were separately fed into the reactor. The precursor powders were obtained by filtering, washing and vacuum drying at 110 \u00b0C overnight. For the Na[Ni0.5Mn0.5]O2 cathode, the obtained spherical precursors were mixed with Na2CO3 (Na:[Ni + Mn] molar ratio = 1.05:1, 5% excess Na2CO3), calcined at 800 \u00b0C for 24 h in an oxygen atmosphere, and quenched under vacuum conditions. For Ca-substituted Na1\u22122xCax[Ni0.5Mn0.5]O2 cathodes, an appropriate amount of Ca(OH)2 was mixed with the [Ni0.5Mn0.5](OH)2 precursor and Na2CO3 (Na:Ca:[Ni + Mn] molar ratio = 1.05\u20132x:x:1, x = 0.01, 0.02, and 0.03) in the same calcination process.", "question": "What's the cathode?", "answer": "Na[Ni0.5Mn0.5]O", "answer_start": 739}
{"document_id": 75454, "context": "Spherical [Ni0.5Mn0.5](OH)2 precursors were synthesized by the co-precipitation method. Stoichiometric amounts of NiSO4\u00b76H2O and MnSO4\u00b7H2O (Samchun Chemical, Korea) were used as starting materials for [Ni0.5Mn0.5](OH)2. The metal solution concentration (2 mol L\u22121 for the metal solution), pH (\u223c11.0), temperature (45 \u00b0C), and stirring speed of the mixture in the batch-type reactor were carefully controlled. At the same time, aqueous NaOH (Samchun, Korea; NaOH/transition metal molar ratio = 2:1) and aqueous NH4OH (Junsei, Japan; NH4OH/transition metal molar ratio = 1.1:1) as chelating agents were separately fed into the reactor. The precursor powders were obtained by filtering, washing and vacuum drying at 110 \u00b0C overnight. For the Na[Ni0.5Mn0.5]O2 cathode, the obtained spherical precursors were mixed with Na2CO3 (Na:[Ni + Mn] molar ratio = 1.05:1, 5% excess Na2CO3), calcined at 800 \u00b0C for 24 h in an oxygen atmosphere, and quenched under vacuum conditions. For Ca-substituted Na1\u22122xCax[Ni0.5Mn0.5]O2 cathodes, an appropriate amount of Ca(OH)2 was mixed with the [Ni0.5Mn0.5](OH)2 precursor and Na2CO3 (Na:Ca:[Ni + Mn] molar ratio = 1.05\u20132x:x:1, x = 0.01, 0.02, and 0.03) in the same calcination process.", "question": "What's the cathode?", "answer": "Na1\u22122xCax[Ni0.5Mn0.5]O2", "answer_start": 987}
{"document_id": 75463, "context": "In addition, the galvanostatic discharge curves of the hybrid battery at different current densities are studied. As displayed in Fig. 6b, a capacity of 785 mA h gZn\u22121 is achieved at the current density of 2 mA cm\u22122 based on the mass of Zn consumed. The result is close to the theoretical value (820 mA h gZn\u22121). It demonstrates the high capacity of the hybrid battery, taking advantage of the Zn\u2013air battery. When the active species in the cathode and the Zn consumed in the anode are both considered, a high gravimetric energy density of 950 W h kg\u22121 is achieved. Therefore, the results demonstrate the high capacity and energy density of the hybrid Zn battery. The stability of the hybrid battery was another crucial criterion for practical applications. As displayed in Fig. 6c, the hybrid battery exhibits good electrochemical durability with stable delivered capacity and charge/discharge profiles during cycling at 2 mA cm\u22122. After one thousand cycles, the voltage of the redox reaction and the ORR/OER process are still well retained (Fig. 6d), demonstrating the good long-term cycling stability of the hybrid zinc battery. In addition, high energy efficiency of 72% is achieved after one thousand cycles, which demonstrates the high efficiency of the hybrid battery.", "question": "What's the anode?", "answer": "Zn", "answer_start": 457}
{"document_id": 75469, "context": "The two-cycled coin-type cells were disassembled in the argon-filled glove box. The cathode electrodes were carefully extracted from the cells and then immediately rinsed in dimethyl carbonate (DMC) solvent to remove electrolyte residues and dried under vacuum overnight. The obtained electrodes were then transferred from the glove box into an oven and treated with different temperatures (210 \u00b0C, 280 \u00b0C, 350 \u00b0C) in the air for four hours. The weight loss during the high-temperature treatment was below 3% of that of the electrode, which primarily resulted from the decomposition of carbon and binder. For comparison, one of the obtained electrodes was kept in the argon-filled glove box at room temperature. After thermal treatment/being kept in the glove box, the electrodes were reassembled into coin-type cells with a fresh Li metal as the counter electrode.", "question": "What's the cathode?", "answer": "dimethyl carbonate (DMC)", "answer_start": 174}
{"document_id": 75474, "context": "Recently, Fan and co-authors proposed a PTCDI derivative with anthraquinone moieties (PTCDI-DAQ 11). This compound has lower solubility than PTCDI due to the increased molecular weight, as well as higher theoretical capacity of 200 mA h g\u22121. The observed Qm was up to 220 mA h g\u22121, again higher than the theoretical value. A decent capacity retention of 73% was demonstrated in the electrolyte with relatively low salt concentration (1 M KPF6 in DME). Moreover, a remarkable capacity of 137 mA h g\u22121 was obtained at 20 A g\u22121. A full cell with pre-potassiated terephthalate (K4TP) anode had a high energy density of 295 W h kg\u22121 (213 mA h g\u22121 \u00d7 1.38 V, calculated per cathode mass), excellent rate capabilities (94 mA h g\u22121 at 10 A g\u22121), and cycling stability (49% and 32% retention after 10000 and 30000 cycles, respectively).", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75466, "context": "Inspired by the superior ORR and OER electrocatalytic activities as well as excellent faradaic redox performance of the DBHF fibers, hybrid Zn batteries were fabricated. In the HZB, the DBHF fibers act as the cathode, Zn nanosheets on carbon cloth serve as the anode and a mixed solution of 6 M KOH and 0.2 M Zn(Ac)2 serves as the electrolyte. The charge/discharge performance of the hybrid Zn battery is investigated. As displayed in Fig. 6a, a smooth and flat voltage plateau at \u223c1.21 V is detected in the initial discharging process, which indicates the ORR process of a typical Zn\u2013air battery. In the subsequent charging process, the two voltage plateaus at \u223c1.85 V and \u223c2.05 V correspond to the M\u2013O oxidation and the OER process, respectively. During the second discharge process, two voltage plateaus appear at \u223c1.74 V and \u223c1.21 V corresponding to the reduction reaction of M\u2013O\u2013OH and the ORR process, respectively. The charge/discharge results are in good agreement with the CV curves (Fig. S7\u2020). Both results demonstrate that the fabricated hybrid battery is able to reversibly store and deliver charges via double sets of electrochemical reactions. They are the ORR/OER reactions in the Zn\u2013air battery and the M\u2013O/M\u2013O\u2013OH redox reaction in the Zn-ion battery assembled in one battery. Such a combination of complementary strength leads to a powerful hybrid Zn battery based on the Zn\u2013air and Zn-ion systems.", "question": "What's the cathode?", "answer": "DBHF fibers", "answer_start": 186}
{"document_id": 75470, "context": "Besides lithium, a modern LIB typically contains non-widespread transition metals, such as copper (anode current collector), nickel and cobalt (cathode materials). The shortage in cobalt is especially acute. If cobalt-free batteries remain underdeveloped, the production of Co will have to increase up to an order of magnitude to satisfy the future demand. Additionally, extraction and processing of transition metals might be harmful to the environment and is typically energy-intensive.", "question": "What's the cathode?", "answer": "nickel and cobalt", "answer_start": 125}
{"document_id": 75470, "context": "Besides lithium, a modern LIB typically contains non-widespread transition metals, such as copper (anode current collector), nickel and cobalt (cathode materials). The shortage in cobalt is especially acute. If cobalt-free batteries remain underdeveloped, the production of Co will have to increase up to an order of magnitude to satisfy the future demand. Additionally, extraction and processing of transition metals might be harmful to the environment and is typically energy-intensive.", "question": "What's the anode?", "answer": "copper", "answer_start": 91}
{"document_id": 75480, "context": "Interestingly, in the presence of Ti-ions as a partial substitute for Mn-ions (as in the case of \u20180.2 Mn/0.3 Ti\u2019 Na-TM-oxide), Mn was found to be completely in the +4 oxidation state (i.e., Mn4+ and not Mn3+) in the pristine electrode, unlike for the \u20180.5 Mn/0 Ti\u2019 counterpart (see ESI Fig. S7d\u2020). Such observations suggest that the presence of Ti-ions suppresses the reduction of Mn4+ to the deleterious Mn3+ during electrode preparation and, thus, improves the stability to some extent. However, similar to the case with \u20180.5 Mn/0 Ti\u2019, Mn3+ did form and the content progressively increased during electrochemical cycling (as inferred from post-cycling XPS data, ESI Fig. S4e\u2020), thus, not totally addressing the problem concerning cycling (in)stability. Of course, in the total absence of Mn-ions, as for the completely Ti-substituted \u20180 Mn/0.5 Ti\u2019 Na-TM-oxide, the oxidation state of Ti-ions remained only as +4 in the as-prepared electrodes, as well as in those cycled for even 100 electrochemical cycles, as can be seen from Fig. 5c and d. In contrast to those observed for the \u2018control\u2019 \u20180.5 Mn/0 Ti\u2019 Na-TM-oxide cathode, neither any notable variation of Vdischarge and Vcharge with cycling could be seen, nor any change in colour of the separator could be noted in the case of the fully Ti-substituted (for Mn-ion) Na-TM-oxide cathode, which indicates non-occurrence of TM-dissolution. Not invoking here, the possible additional contribution towards capacity fading from Jahn\u2013Teller distortion of Mn3+ ( ) during electrochemical cycling, the oxidation states of TM-ions at the surface of the Na-TM-oxides, in particular the presence/formation of Mn3+ and its likely dissolution into the electrolyte, presents a strong justification for the capacity fading in the presence of Mn-ions and mitigation of the same upon Ti-substitution. In this case, electrode impedance is also likely to be considerably affected by the replacement of Mn-ions by Ti-ions, as discussed in the following sections.", "question": "What's the cathode?", "answer": "Ti-substituted (for Mn-ion) Na-TM-oxid", "answer_start": 1293}
{"document_id": 75476, "context": "Later, Chen et al. used K2TP under similar conditions as the anode for hybrid supercapacitors. Activated carbon was used as the cathode. Energy of 101 W h kg\u22121 and power of 2.16 kW kg\u22121 based on the mass of two electrodes were demonstrated. If the electrolyte mass was included, the values reached 41.5 W h kg\u22121 and 885 W kg\u22121, respectively. The capacity retention of the supercapacitor was 97.7% in 500 cycles. In half cells, the capacity of K2TP at 5 A g\u22121 was 124 mA h g\u22121.", "question": "What's the cathode?", "answer": "carbon ", "answer_start": 105}
{"document_id": 75476, "context": "Later, Chen et al. used K2TP under similar conditions as the anode for hybrid supercapacitors. Activated carbon was used as the cathode. Energy of 101 W h kg\u22121 and power of 2.16 kW kg\u22121 based on the mass of two electrodes were demonstrated. If the electrolyte mass was included, the values reached 41.5 W h kg\u22121 and 885 W kg\u22121, respectively. The capacity retention of the supercapacitor was 97.7% in 500 cycles. In half cells, the capacity of K2TP at 5 A g\u22121 was 124 mA h g\u22121.", "question": "What's the anode?", "answer": "K2TP ", "answer_start": 24}
{"document_id": 75481, "context": "To obtain strong immobilization and fast conversion kinetics for polysulfides, the concept of constructing highly adsorptive and catalyzing heterostructures has been widely developed, such as TiN\u2013TiO2, MoN\u2013VN, and WS2\u2013WO3. In fact, the anchoring of polysulfides as well as Li2S precipitation are part of a continuous multielectron redox reaction in a working battery, and thus an integrated platform, such as 1T MoS2 NDs in this work, enabling smooth \u201cimmobilization\u2013diffusion\u2013conversion\u201d is highly appealing. The unique advantages for 1T MoS2 ND can be summarized as following: (i) the edge-rich NDs with an intrinsically strong affinity to polysulfides serve as anchoring sites for LPSs and accelerate their reduction, which contributes to the long cycle life and high sulfur utilization; (ii) the highly conductive and catalytic nature of 1T MoS2 NDs uniformly loaded on conductive substrates can facilitate Li\u2013S reaction kinetics (Fig. S14, ESI\u2020) and reduce the cell resistance, which benefits the high rate performance of MoS2 ND-modified cathodes; (iii) the well-defined morphology and phase of MoS2 maximize the active sites to fully demonstrate their potential for Li\u2013S chemistry, which enables a boost of the electrochemical performance with a small amount of electrochemical inert catalysts. In addition, post-mortem analyses revealed that MoS2 NDs/porous carbon remained stable after cycling (Fig. S15, ESI\u2020). To further determine whether the excellent catalytic performance of the MoS2 NDs could be retained during long-term cycling, the MoS2 ND/porous carbon/Li2S6 cathode was prolonged to 500 cycles at 0.5C (Fig. S16, ESI\u2020), and exhibited only a low capacity fading rate of 0.08% per cycle, directly indicating the stability of the MoS2 NDs as a catalyst in long-term Li\u2013S batteries. Finally, thanks to the facile fabrication method and the low content needed to improve LSB performance, the large-scale application of 1T MoS2 NDs in high-energy LSBs should not be problematic.", "question": "What's the cathode?", "answer": "MoS2 ND-modified", "answer_start": 1027}
{"document_id": 75481, "context": "To obtain strong immobilization and fast conversion kinetics for polysulfides, the concept of constructing highly adsorptive and catalyzing heterostructures has been widely developed, such as TiN\u2013TiO2, MoN\u2013VN, and WS2\u2013WO3. In fact, the anchoring of polysulfides as well as Li2S precipitation are part of a continuous multielectron redox reaction in a working battery, and thus an integrated platform, such as 1T MoS2 NDs in this work, enabling smooth \u201cimmobilization\u2013diffusion\u2013conversion\u201d is highly appealing. The unique advantages for 1T MoS2 ND can be summarized as following: (i) the edge-rich NDs with an intrinsically strong affinity to polysulfides serve as anchoring sites for LPSs and accelerate their reduction, which contributes to the long cycle life and high sulfur utilization; (ii) the highly conductive and catalytic nature of 1T MoS2 NDs uniformly loaded on conductive substrates can facilitate Li\u2013S reaction kinetics (Fig. S14, ESI\u2020) and reduce the cell resistance, which benefits the high rate performance of MoS2 ND-modified cathodes; (iii) the well-defined morphology and phase of MoS2 maximize the active sites to fully demonstrate their potential for Li\u2013S chemistry, which enables a boost of the electrochemical performance with a small amount of electrochemical inert catalysts. In addition, post-mortem analyses revealed that MoS2 NDs/porous carbon remained stable after cycling (Fig. S15, ESI\u2020). To further determine whether the excellent catalytic performance of the MoS2 NDs could be retained during long-term cycling, the MoS2 ND/porous carbon/Li2S6 cathode was prolonged to 500 cycles at 0.5C (Fig. S16, ESI\u2020), and exhibited only a low capacity fading rate of 0.08% per cycle, directly indicating the stability of the MoS2 NDs as a catalyst in long-term Li\u2013S batteries. Finally, thanks to the facile fabrication method and the low content needed to improve LSB performance, the large-scale application of 1T MoS2 NDs in high-energy LSBs should not be problematic.", "question": "What's the cathode?", "answer": "MoS2 ND/porous carbon/Li2S6", "answer_start": 1550}
{"document_id": 75486, "context": "To investigate the failure mechanism of the overcharge protection of the TDAC, a scaled-up NCA/graphite cell was employed to reclaim enough electrolyte and electrode materials for a post-mortem analysis. The reclaimed electrolyte after overcharge was in a brownish color, which could be contributed by the dissolution of the transition metals (Co and Ni) from the cathode, the decomposition products of the electrolyte solvent, or the TDAC molecules in the harsh overcharge environment. MS, NMR and CV were used to analyse the reclaimed electrolyte in comparison with the fresh electrolyte. Fig. 5a shows a peak at a 283.2 mass/charge ratio (m/z) for both electrolytes. The MS data confirmed the existence of TDAC cation species in both electrolytes. The similar intensity of the peaks indicated that the concentration of the TDAC in the overcharged electrolyte was about the same as that in the fresh one. NMR analysis as shown in Fig. 5b also confirmed that most of the TDACs remained intact since no TDAC decomposed compounds were detected. The CV profile in Fig. 5c reveals a pair of reversible redox peaks at \u223c1.35 V vs. Fc+/Fc, exhibiting no discrepancy against the fresh TDAC electrolyte. The reclaimed electrolyte was then injected into a cell with new NCA and graphite sheets. As displayed in Fig. 5d, the potential plateau at \u223c4.5 V reappeared in the reassembled cell despite a lower CE and a decreased capacity.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75496, "context": "For full cells, commercial lithium iron phosphate (LFP) was used as the cathode material. A mixture of LFP powder, acetylene black (conductive additive) and polyvinylidene fluoride (PVDF) with a mass ratio of 8:1:1 in N-methyl-2-pyrrolidone (NMP) was first coated on aluminum foil, dried in a vacuum oven at 80 \u00b0C overnight and used as the LFP cathode. The areal mass loading of LFP was around 5 mg cm\u22122. The charge\u2013discharge voltage was recorded from 2.0 to 4.0 V while the current rate varied from 0.2 to 2.0C (1C is equals to 170.0 mA h g\u22121). Electrochemical impedance spectroscopy (EIS) measurements were performed on an IVIUM electrochemical workstation with a frequency range of 105\u20130.01 Hz.", "question": "What's the cathode?", "answer": " lithium iron phosphate (LFP)", "answer_start": 26}
{"document_id": 75496, "context": "For full cells, commercial lithium iron phosphate (LFP) was used as the cathode material. A mixture of LFP powder, acetylene black (conductive additive) and polyvinylidene fluoride (PVDF) with a mass ratio of 8:1:1 in N-methyl-2-pyrrolidone (NMP) was first coated on aluminum foil, dried in a vacuum oven at 80 \u00b0C overnight and used as the LFP cathode. The areal mass loading of LFP was around 5 mg cm\u22122. The charge\u2013discharge voltage was recorded from 2.0 to 4.0 V while the current rate varied from 0.2 to 2.0C (1C is equals to 170.0 mA h g\u22121). Electrochemical impedance spectroscopy (EIS) measurements were performed on an IVIUM electrochemical workstation with a frequency range of 105\u20130.01 Hz.", "question": "What's the cathode?", "answer": "LFP", "answer_start": 340}
{"document_id": 75482, "context": "Lithium\u2013sulphur (Li\u2013S) batteries with high theoretical capacity, cost-effectiveness and environmental sustainability have attracted tremendous interest as the next generation rechargeable batteries. However, the performance of Li\u2013S batteries is constrained by sulphur's low conductivity and large volume change during lithiation/delithiation. As the cathode matrix for the sulphur cathode, h-BNNS with nitrogen vacancies (v-BN) were found to improve the cycling performance of Li\u2013S batteries. Compared with the pristine h-BN electrode, the v-BN electrode demonstrated significantly improved capacity. The engineered vacancies were believed to improve the kinetics of polysulphide conversion, lithium-ion diffusion rate, and protection of the Li anode from corrosion.", "question": "What's the cathode?", "answer": "sulphur ", "answer_start": 373}
{"document_id": 75487, "context": "The hybrid Na\u2013air battery was assembled in a sandwich structure. Initially, the anode part of the hybrid Na\u2013air cell was fabricated in a glove box. The metallic sodium was cut and pressed into a sheet with a diameter of 10 mm as the anode, followed by the injection of organic electrolyte (1 M NaClO4 in tetraethylene glycol dimethyl ether) into the anode chamber. The solid electrolyte NASICON was sealed as the separator for the anode and cathode chamber, ensuring that one side of the NASICON was in contact with the organic electrolyte and the other side was exposed to air. The NASICON solid electrolyte was chosen to avoid direct contact between the aqueous electrolyte and Na anode, and specifically allow Na ions to shuttle between the anode and cathode during the reactions. The cathode compartment was built under ambient air by directly immersing the air electrode in the O2-saturated 0.1 M NaOH electrolyte. The as-prepared electrocatalysts coated on NF (diameter 10 mm) were directly used as air cathodes. For comparison, the 20% Pt/C (Macklin) and RuO2 catalysts cast on NF (diameter 10 mm) were prepared with a mass loading of 1 mg cm\u22122.", "question": "What's the cathode?", "answer": "air ", "answer_start": 1005}
{"document_id": 75536, "context": "Yao et al. presented a series of aqueous systems with quinone-based anodes and industrially established cathodes, which showed excellent stability, kinetics and energy density. Particularly for K-based batteries, PAQS P1 was paired with Ni(OH)2 in alkaline media (10 M KOH). The anode showed a capacity of 200 mA h g\u22121. At r.t., the full cell energy density (79 W h kg\u22121/138 W h L\u22121) was smaller than for a nickel metal hydride battery (180 W h kg\u22121/597 W h L\u22121), partially due to a relatively high anode potential. However, the capacity retention (88% after 1300 cycles) was better than for the best metal hydrides. Moreover, the capacity of PAQS decreased only by 7% as the temperature decreased from 25 to \u221225 \u00b0C. It is in contrast with Ni-MmH, whose energy density significantly decreases at lower temperatures.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75457, "context": "Compared with graphite, Bi, Sb and P, organic-based materials are less attractive in terms of the potentials. The electrode capacities are also generally lower, although several materials with high demetalation potentials showed a Qe of above 250 mA h g\u22121. Areal capacities (Chart 5c) are mostly comparable for organic-based materials and the benchmarks, except for graphite, for which very high loadings (up to 28.56 mg cm\u22122, corresponding to \u223c7.4 mA h cm\u22122) were demonstrated. Similar to the cathodes (Section 2.7), the material loading of the anodes is typically left unoptimized.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75462, "context": "The determination of metal and polymer material moduli are straightforward and taken from literature values. To verify the estimated moduli of the composite electrodes, they were stacked in various layers and acoustically interrogated. As shown in Fig. 3a, the graphite/Cu electrode has a modulus of 10.7 GPa, and the LiCoO2/Al electrode has a modulus of around 27.8 GPa, as calculated from the measured wave velocities (Fig. 3c) and the respective weighted densities of the double-sided electrodes. These values are slightly higher than the respective Hashin\u2013Shtrikman bounds because the measured electrodes include the metal current collector which has a higher modulus. The values are lower than the single particle graphite or LiCoO2 because the composite electrodes are weighted down by the softer materials. The change in thickness of these individual electrodes during cycling can also be estimated from average peak-to-peak spacing of the intensity line profiles generated from TXM micrographs (Fig. S3\u2020). These peak-to-peak intensities vary because of pouch cell manufacturing tolerances: the electrodes are not perfectly aligned within the cell, causing signal blurring at electrode boundaries. This percent error in thickness calculation is minimized by introducing threshold values for peak discrimination. The results of the peak spacing analysis (Fig. S4\u2020) show that the average single layer expands upon charge and contracts upon discharge, and that the degree of hysteresis grows with current rate. The initial average electrode thickness of 170 \u03bcm confirms the ex situ digital caliper measurements of individual electrodes (180 \u03bcm for LiCoO2/Al and 200 \u03bcm for graphite/Cu) and the moduli estimation of 27.8 GPa for LiCoO2/Al and 10.7 GPa for graphite/Cu. Unfortunately, the differences in thickness changes between LiCoO2/Al and graphite/Cu during cycling are hard to discern due to the imperfect alignment of the electrode layers with the X-ray detector. For future studies, improved spatial resolution at the single electrode length scale would be aided by tests of single-layer pouch cells, where thicknesses of the single anode and cathode could be measured more accurately without stack distortion.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75462, "context": "The determination of metal and polymer material moduli are straightforward and taken from literature values. To verify the estimated moduli of the composite electrodes, they were stacked in various layers and acoustically interrogated. As shown in Fig. 3a, the graphite/Cu electrode has a modulus of 10.7 GPa, and the LiCoO2/Al electrode has a modulus of around 27.8 GPa, as calculated from the measured wave velocities (Fig. 3c) and the respective weighted densities of the double-sided electrodes. These values are slightly higher than the respective Hashin\u2013Shtrikman bounds because the measured electrodes include the metal current collector which has a higher modulus. The values are lower than the single particle graphite or LiCoO2 because the composite electrodes are weighted down by the softer materials. The change in thickness of these individual electrodes during cycling can also be estimated from average peak-to-peak spacing of the intensity line profiles generated from TXM micrographs (Fig. S3\u2020). These peak-to-peak intensities vary because of pouch cell manufacturing tolerances: the electrodes are not perfectly aligned within the cell, causing signal blurring at electrode boundaries. This percent error in thickness calculation is minimized by introducing threshold values for peak discrimination. The results of the peak spacing analysis (Fig. S4\u2020) show that the average single layer expands upon charge and contracts upon discharge, and that the degree of hysteresis grows with current rate. The initial average electrode thickness of 170 \u03bcm confirms the ex situ digital caliper measurements of individual electrodes (180 \u03bcm for LiCoO2/Al and 200 \u03bcm for graphite/Cu) and the moduli estimation of 27.8 GPa for LiCoO2/Al and 10.7 GPa for graphite/Cu. Unfortunately, the differences in thickness changes between LiCoO2/Al and graphite/Cu during cycling are hard to discern due to the imperfect alignment of the electrode layers with the X-ray detector. For future studies, improved spatial resolution at the single electrode length scale would be aided by tests of single-layer pouch cells, where thicknesses of the single anode and cathode could be measured more accurately without stack distortion.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75467, "context": "However, in the extreme case, when Qm of a dual-ion battery cathode is 300 mA h g\u22121 and the average potential is 5.0 V, Ecorrm is only \u223c500 W h kg\u22121 if KPF6 is used as the supporting salt (Chart 2b). Switching to lighter salts, such as KClO4, KBF4 and particularly KF might significantly boost the energy density (Chart 2c). For potassium fluoride, an Ecorrm of \u223c500 W h kg\u22121 is achieved already at a reasonable \u223c200 mA h g\u22121 and 3.6 V. Optimization of the salt composition, however, has not been reported yet. Considering low solubility of KF in aprotic electrolytes, it is especially intriguing if it may succeed as the supporting salt.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75490, "context": "Uniform doping has been recognized as an effective approach to improve the cycling performance of many layered cathodes. Herein, we propose non-uniform doping as a more effective approach to enhance the cycling stability of layered cathodes via the precipitation strengthening mechanism. In this work, we investigate four doped (Cu, Ti, Mg, and Zn) P2-layered cathodes for sodium ion batteries and validate that cycling induced dopant segregation can substantially enhance the cyclability due to mitigation of bulk cracking. Our comprehensive analysis indicates that dopant evolution is quite diverse during electrochemical cycling, not only depending on the nature of each dopant but also the cycling conditions applied. The migration and segregation behaviors of inactive dopants demonstrate the complex dynamics within grain bulk during battery cycling, which also offers us chances to engineer the physicochemical properties of layered cathodes. Non-uniform doping opens a new avenue for designing battery materials with superior mechanical properties.", "question": "What's the cathode?", "answer": "doped (Cu, Ti, Mg, and Zn) P2-layered", "answer_start": 322}
{"document_id": 75489, "context": "To probe the surface chemistry of MoS2 NDs before and after LPS adsorption, XPS measurements were carried out. Fig. S7 (ESI\u2020) shows the deconvoluted Mo 3d and S 2p spectra of the pristine and polysulfides-mixed MoS2 NDs. In comparison with the pristine MoS2 NDs, the Mo 3d peaks of 3d3/2 and 3d5/2 for the MoS2 ND/polysulfide were overall downshifted by \u223c0.15 eV, which could be attributed to the intense interaction of the exposed Mo atoms with the surrounding strong electronegative sulfur ligand. In the S 2p spectra, peaks centered at 163.2, 162.6, and 161.3 eV, corresponding to the S 2p1/2 and 2p3/2 components of the original MoS2 ND, were almost intact after mixing with the polysulfides, possibly due to the weak interaction between the S atoms in the MoS2 NDs and polysulfides. Interestingly, new features located at 159.8 and 165.2\u2013169.4 eV appeared for the MoS2 ND/polysulfide, which were considered due to the formation of the polythionate moiety. It is reasonable to deduce that the \u201csulfiphilic\u201d surface for MoS2 NDs would significantly promote the retention of polysulfides in the cathode region. More importantly, the edge-rich MoS2 NDs increased the Mo\u2013S bridge between the metallic catalyst and polysulfides, propelling electron transfer across the MoS2 NDs to the polysulfides, and thus significantly catalyzing the chemical redox conversion of the polysulfides.", "question": "What's the cathode?", "answer": "MoS2 NDs", "answer_start": 1023}
{"document_id": 75494, "context": "Overall, crosslinking the sensitizers under copper-free conditions lead to an increase of the photovoltaic performances of all the DSSCs with both electrolytes. For NiO photocathodes, the Jsc is decreased owing to most probable iodide association with triazole, but it is compensated with the increase of Voc and ff. Crosslinking of the dyes with copper(I) catalysis is also possible, but the resulting solar cells exhibit lower performances, showing that copper has poisoned the devices.", "question": "What's the cathode?", "answer": "NiO ", "answer_start": 165}
{"document_id": 75499, "context": "Compounds derived from hexaazatriphenylene (HAT) might reversibly accept up to six electrons per HAT unit and have excellent cycling capabilities. They might withstand 10000\u201350000 cycles with small capacity fading. Kapaev et al. showed that HAT-based polymer P14 delivered a Qm of up to 245 mA h g\u22121 at 50 mA g\u22121 in a 0.9\u20133.4 V vs. K potential range. Interestingly, the reversible capacity continuously increased upon cycling at 10 A g\u22121 from 150 to 169 mA h g\u22121 after 4600 cycles. This slow activation, of which the reasons are yet unknown, makes P14 the most stable among all reported cathode materials for non-aqueous K-based batteries. After 4600 cycles, the cells short-circuited due to dendrite formation at the potassium anode.", "question": "What's the cathode?", "answer": "P14 ", "answer_start": 548}
{"document_id": 75504, "context": "Volumetric capacity and density are usually unreported for organic materials used in potassium batteries. Density for solid polar organic compounds containing only C, H, N and O ranges between roughly 1.1 and 1.7 g cm\u22123, and it is smaller than for inorganic cathode materials (calc. 2.3 g cm\u22123 for KMHCF, calc. 3.1 g cm\u22123 for KVPO4F, and 3.35 g cm\u22123 for V2O5 ( )). This limits the applicability of organic cathode materials where the low device volume is crucial, e.g., in portable electronics. However, in some electric vehicles and large-scale stationary applications the volume is supposed to be less restricted.", "question": "What's the cathode?", "answer": "KMHCF", "answer_start": 298}
{"document_id": 75504, "context": "Volumetric capacity and density are usually unreported for organic materials used in potassium batteries. Density for solid polar organic compounds containing only C, H, N and O ranges between roughly 1.1 and 1.7 g cm\u22123, and it is smaller than for inorganic cathode materials (calc. 2.3 g cm\u22123 for KMHCF, calc. 3.1 g cm\u22123 for KVPO4F, and 3.35 g cm\u22123 for V2O5 ( )). This limits the applicability of organic cathode materials where the low device volume is crucial, e.g., in portable electronics. However, in some electric vehicles and large-scale stationary applications the volume is supposed to be less restricted.", "question": "What's the cathode?", "answer": "KVPO4F", "answer_start": 326}
{"document_id": 75500, "context": "High energy density lithium ion batteries have been applied as the main energy storage technology in portable devices and green transportation. LiCoO2, a layered oxide cathode in lithium ion batteries, has obtained unprecedented success since its commercialization in the 1990s. LiNiO2, isostructural to LiCoO2, can deliver a higher capacity within a relatively low upper cutoff voltage. However, its practical application has been hindered due to the inherent structural instability. Thus, cobalt, as an essential element, has been incorporated into the LiNiO2 system to form LiNi1\u2212x\u2212yMnyCoxO2 (NMC) and LiNi1\u2212x\u2212yCoxAlyO2 (NCA) materials to release the strong magnetic moment and ultimately stabilize the structure. At present, researchers are pursuing the theoretical capacity of NMCs either by elevating the high cutoff voltage or increasing the nickel concentration. However, these strategies have inevitably provoked some of the degradation pathways of these materials, including transition metal reduction/dissolution, surface reconstruction, gas evolution, electrolyte oxidation/decomposition, and chemomechanical breakdown. Additionally, most of these materials are synthesized in the polycrystalline form and have heterogeneous chemistry, resulting in high heterogeneous degradation patterns.", "question": "What's the cathode?", "answer": "LiCoO2", "answer_start": 144}
{"document_id": 75502, "context": "Against this backdrop, the presently reported work focuses on designing a composition (viz., combination of TM- and non-TM-ions) and suitably tuning some structural features of O3-type Na-TM-oxide based cathode materials to address the main issue concerning stability against hydration and also improve the electrochemical cyclic stability, as well as rate capability. While doing so, a strong correlation between the composition, structure, stability against hydration and electrochemical behavior/performance for such oxides has been established. As will be demonstrated, an air/water-stable (despite long-term exposures under stringent conditions) O3-type Na-TM-oxide has been developed, which is devoid of all the problems mentioned above, so much so that it allows the successful development of stable electrodes using a cost-effective and environment/health friendly \u2018water based binder\u2019 (i.e., Na-alginate) and water as solvent during electrode preparation (viz., \u2018aqueous processing\u2019). To the best of our knowledge, such excellent stability against hydration and electrochemical performance, despite being \u2018aqueous-processed\u2019, have not been reported earlier for O3-type Na-TM-oxide based cathodes.", "question": "What's the cathode?", "answer": "O3-type Na-TM-oxide based", "answer_start": 177}
{"document_id": 75502, "context": "Against this backdrop, the presently reported work focuses on designing a composition (viz., combination of TM- and non-TM-ions) and suitably tuning some structural features of O3-type Na-TM-oxide based cathode materials to address the main issue concerning stability against hydration and also improve the electrochemical cyclic stability, as well as rate capability. While doing so, a strong correlation between the composition, structure, stability against hydration and electrochemical behavior/performance for such oxides has been established. As will be demonstrated, an air/water-stable (despite long-term exposures under stringent conditions) O3-type Na-TM-oxide has been developed, which is devoid of all the problems mentioned above, so much so that it allows the successful development of stable electrodes using a cost-effective and environment/health friendly \u2018water based binder\u2019 (i.e., Na-alginate) and water as solvent during electrode preparation (viz., \u2018aqueous processing\u2019). To the best of our knowledge, such excellent stability against hydration and electrochemical performance, despite being \u2018aqueous-processed\u2019, have not been reported earlier for O3-type Na-TM-oxide based cathodes.", "question": "What's the cathode?", "answer": "O3-type Na-TM-oxide based", "answer_start": 1170}
{"document_id": 75503, "context": "This simple, yet methodical sonication method can be applied to evaluate the surface stability of inorganic materials. In particular, the agglomerated secondary particles require a dispersing process to prepare samples for the TEM analysis. In addition, an extended sonication may be necessary in the cycled electrodes because of the binder usage. Our results have also shown that the surface of layered oxide materials can be easily influenced by the sonication method. Furthermore, our previous study also demonstrated that the cathode surface can be transformed by simply soaking layered oxide powders in organic solvents, including typical electrolyte solvents. With the inherent surface fragility of Ni-rich oxide materials, it is crucial to take cautions in preparing samples for characterization. Alternatively, many studies have applied focused ion beam (FIB) to prepare thin samples for TEM experiments. In this case, the chemical and structural information around grain boundaries can be protected for TEM analysis. However, it is not clear how the surface region may be influenced by the typical FIB coating protection and sample handling.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75508, "context": "Research focus on cathode materials for LIBs is currently going through a paradigm shift where the previously overlooked disordered rocksalt (DRS) materials are receiving an increasing level of interest. It was reported that Li-rich materials with a high Li-to-TM ratio allow the formation of percolating network with low energy barriers for Li diffusion, which leads to good transport properties while its structural integrity is retained. Several Li-rich transition metal oxides with a DRS structure such as Li1+xTi2xFe1\u22123xO2 (0 \u2264 x \u2264 0.333), Li1.2Ni1/3Ti1/3Mo2/5O2, Li1.2Ti0.4Mn0.4O2, Li1.3Nb0.3Fe0.4O2 ( ) and Li1.3Nb0.43Ni0.27O2 ( ) have been studied, and their high reversible capacities showed a promising prospect of discovering new cathode material in much less explored domain. Li2VO2F is the first Li-rich DRS material where O was partially substituted by F. The substitution increases the performance of the cathode such as discharge capacity and nominal voltage.", "question": "What's the cathode?", "answer": "Li2VO2F ", "answer_start": 788}
{"document_id": 75501, "context": "To achieve aqueous zinc batteries with high capacity and superior durability, developing a scalable and efficient strategy for preparing an outstanding cathode is of pivotal importance. Herein, porous cobalt/nickel composite hydroxides supported on 3D Co\u2013Ni foam (CNF) are used to construct a robust cathode (denoted as UTCNF) via a facile and cost-effective ultrasonic method that is suitable for scaling up to an industrial level. Attributed to the synergistic effects of the 3D foam architecture, the porous structure, and the in situ formation of electrochemically active cobalt/nickel composite hydroxides, the UTCNF//Zn battery exhibits excellent performance with a relatively high capacity (2.13 mA h cm\u22122 at 8 mA cm\u22122), excellent rate performance (47% capacity retention from 8 to 50 mA h cm\u22122), and superb stability (only \u223c10% capacity loss after 30000 cycles at a high current density of 40 mA cm\u22122). Furthermore, a maximum energy density of 3.99 mW h cm\u22122 and a peak density of 320 mW cm\u22122 are also attained. Notably, a soft-package battery that uses the UTCNF as a cathode demonstrates great potential as a power supply. This work may provide valuable ideas for the achievement of large-scale aqueous zinc batteries with high performance.", "question": "What's the cathode?", "answer": "UTCNF", "answer_start": 320}
{"document_id": 75501, "context": "To achieve aqueous zinc batteries with high capacity and superior durability, developing a scalable and efficient strategy for preparing an outstanding cathode is of pivotal importance. Herein, porous cobalt/nickel composite hydroxides supported on 3D Co\u2013Ni foam (CNF) are used to construct a robust cathode (denoted as UTCNF) via a facile and cost-effective ultrasonic method that is suitable for scaling up to an industrial level. Attributed to the synergistic effects of the 3D foam architecture, the porous structure, and the in situ formation of electrochemically active cobalt/nickel composite hydroxides, the UTCNF//Zn battery exhibits excellent performance with a relatively high capacity (2.13 mA h cm\u22122 at 8 mA cm\u22122), excellent rate performance (47% capacity retention from 8 to 50 mA h cm\u22122), and superb stability (only \u223c10% capacity loss after 30000 cycles at a high current density of 40 mA cm\u22122). Furthermore, a maximum energy density of 3.99 mW h cm\u22122 and a peak density of 320 mW cm\u22122 are also attained. Notably, a soft-package battery that uses the UTCNF as a cathode demonstrates great potential as a power supply. This work may provide valuable ideas for the achievement of large-scale aqueous zinc batteries with high performance.", "question": "What's the cathode?", "answer": "UTCNF ", "answer_start": 1066}
{"document_id": 75506, "context": "Electrospun NiO with different nanostructures has also been widely studied in SCs. For instance, by electrospinning a PVP/nickel nitrate/citric acid polymer solution followed by a subsequent annealing process to remove PVP, NiO hollow nanofibers comprised of NiO sheets with a diameter of 17 nm were prepared. The resultant NiO nanofibers exhibited a higher pseudocapacitance (336 F g\u22121 at 5 mA cm\u22122) than the solid NiO nanofibers fabricated without citric acid (136 F g\u22121). In another reference, by using electrospun PAA as a sacrificial template, NiO hollow nanofibers consisting of NiO nanoparticles with diameters varying from 10 to 30 nm were synthesized through a direct ion-exchange process in oversaturated Ni(NO3)2 solution, followed by air annealing. The NiO nanofibers with a porous structure and empty space can accommodate large volume changes and exhibited a high specific capacitance of 700 F g\u22121 at 2 A g\u22121, as well as a remarkable rate capability (80% capacitance retention with the current density increasing from 1 to 5 A g\u22121). In addition, electrospun nickel acetate/PVP-derived NiO nanofibers were applied as cathode materials for ASCs (AC as the anode). The device delivered a specific capacitance of 141 F g\u22121 with an energy density of 43.75 W h kg\u22121 and power density of 7.5 kW kg\u22121.", "question": "What's the cathode?", "answer": "nickel acetate/PVP-derived NiO nanofibers", "answer_start": 1072}
{"document_id": 75512, "context": "Long-term cyclic stability of symmetric cells. One of the most promising applications of metal anodes is to combine them with a sulfur or air cathode with a high energy density. It is thus important to find an efficient way of infusing the alkali metal inside the anode scaffold. To introduce Na in the network, the anode was pre-assembled by stacking the CNF film on top of a pure Na foil. The Na foil was manually pressed into a thickness ranging between 200 and 400 \u03bcm. The use of this stacked design saved materials and processing time better than the classical sacrificial-cell electrodeposition method. The thickness of Na foil could be further reduced using industrial pressing tools. Fig. 6a presents a schematic of the stacking scheme of the assembled electrode which allowed Na to be effectively stripped and plated by removal and re-infiltration into the fiber network. Fig. 6b presents a side view of the CNF film stacked on top of a Na layer after 6 mA h cm\u22122 of Na was stripped and re-deposited at a current density of 1 mA cm\u22122. The image signifies successful re-infiltration of Na in the fiber network after the two-step process. The fiber diameter increased to \u223c600\u2013800 nm from the initial \u223c150 nm, proving a large load of deposited Na. The final fiber thickness obtained with the stacked design was compatible with the thickness obtained with regular electrodeposition, indicating that a majority of Na was infiltrated from the initial film into the network. In view of the large variation in the measured Na thicknesses, however, it may be possible that some part of Na had been redeposited back onto the original Na film, as shown in the schematics. The above fiber network was likely to hinder any dendritic growth resulting from this scenario. The overall ZNO@CNF film thickness remained at \u223c100 \u03bcm after infiltration, suggesting that the network could withstand the mechanical pressure inside of the cell while retaining its original shape. The smooth top view of the same anode shown in Fig. S26\u2020 indicates that the ZnO@CNF film was able to hold and control the deposited Na even with a high areal loading of 6 mA h cm\u22122.", "question": "What's the cathode?", "answer": "sulfur ", "answer_start": 128}
{"document_id": 75512, "context": "Long-term cyclic stability of symmetric cells. One of the most promising applications of metal anodes is to combine them with a sulfur or air cathode with a high energy density. It is thus important to find an efficient way of infusing the alkali metal inside the anode scaffold. To introduce Na in the network, the anode was pre-assembled by stacking the CNF film on top of a pure Na foil. The Na foil was manually pressed into a thickness ranging between 200 and 400 \u03bcm. The use of this stacked design saved materials and processing time better than the classical sacrificial-cell electrodeposition method. The thickness of Na foil could be further reduced using industrial pressing tools. Fig. 6a presents a schematic of the stacking scheme of the assembled electrode which allowed Na to be effectively stripped and plated by removal and re-infiltration into the fiber network. Fig. 6b presents a side view of the CNF film stacked on top of a Na layer after 6 mA h cm\u22122 of Na was stripped and re-deposited at a current density of 1 mA cm\u22122. The image signifies successful re-infiltration of Na in the fiber network after the two-step process. The fiber diameter increased to \u223c600\u2013800 nm from the initial \u223c150 nm, proving a large load of deposited Na. The final fiber thickness obtained with the stacked design was compatible with the thickness obtained with regular electrodeposition, indicating that a majority of Na was infiltrated from the initial film into the network. In view of the large variation in the measured Na thicknesses, however, it may be possible that some part of Na had been redeposited back onto the original Na film, as shown in the schematics. The above fiber network was likely to hinder any dendritic growth resulting from this scenario. The overall ZNO@CNF film thickness remained at \u223c100 \u03bcm after infiltration, suggesting that the network could withstand the mechanical pressure inside of the cell while retaining its original shape. The smooth top view of the same anode shown in Fig. S26\u2020 indicates that the ZnO@CNF film was able to hold and control the deposited Na even with a high areal loading of 6 mA h cm\u22122.", "question": "What's the cathode?", "answer": "air ", "answer_start": 138}
{"document_id": 75514, "context": "Ni foams, typical 3D porous substrates, are extensively employed as current collectors/supports in energy storage devices, because they not only afford large surface areas and easy electrolyte access, but also enable efficient ion diffusion and charge transfer. For example, Chen and coworkers designed hierarchical micro-nano sheet arrays of nickel\u2013cobalt double hydroxide supported on Ni foam (NiCo-DH) via an etching-deposition-growth strategy. The corresponding Ni\u2013Zn battery with a NiCo-DH electrode as the cathode delivered a high specific capacity of 329 mA h g\u22121. Wang et al. synthesized a Co3O4@NiV-LDH nanowires array grown on the surface of a Ni foam with a hierarchical structure. When used as the cathode, the assembled battery demonstrated a satisfactory capacity of \u223c1.25 mA h cm\u22122. Despite the favorable electrochemical performance of these cathodes, the complicated or multi-step preparation processes required substantially impede their industrial application. Furthermore, the ex situ formed active materials deposited on the Ni foam are unavoidably peeled off during long-term charge\u2013discharge tests, which may cause trouble for the cyclic stability of zinc batteries.", "question": "What's the cathode?", "answer": "Co3O4@NiV-LDH", "answer_start": 598}
{"document_id": 75515, "context": "Typically, a certain amount of P(VDF-HFP) powder and BaTiO3 piezoelectric particles (4:1 in m/m) were firstly added into a mixture of N,N-dimethylformamide (DMF) and deionized (DI) water under constant stirring at ambient temperature, forming a well-dispersed solution. The solution was then spread on a clean glass substrate, followed by an immersion in a flowing water bath at 80 \u00b0C. Several minutes later, a homogeneous white BaTiO3-P(VDF-HFP) film was obtained and self-peeled off from the glass substrate. Next, the film was dried at 100 \u00b0C under vacuum to remove the containing water. Afterwards, the dried film was punched according to the size of the anode or cathode, followed by an appropriate polarization under a DC field of 3.5 kV mm\u22121 in air atmosphere at ambient temperature for 0.5 h. Finally, the polarized pieces were fully soaked in a liquid electrolyte of 1 mol L\u22121 NaClO4 dissolved in propylene carbonate (PC) with a 5 vol% fluorinated ethylene carbonate (FEC) additive in a glove box over 24 h, yielding the desired BaTiO3-P(VDF-HFP)-NaClO4 piezoelectric gel-electrolyte.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75515, "context": "Typically, a certain amount of P(VDF-HFP) powder and BaTiO3 piezoelectric particles (4:1 in m/m) were firstly added into a mixture of N,N-dimethylformamide (DMF) and deionized (DI) water under constant stirring at ambient temperature, forming a well-dispersed solution. The solution was then spread on a clean glass substrate, followed by an immersion in a flowing water bath at 80 \u00b0C. Several minutes later, a homogeneous white BaTiO3-P(VDF-HFP) film was obtained and self-peeled off from the glass substrate. Next, the film was dried at 100 \u00b0C under vacuum to remove the containing water. Afterwards, the dried film was punched according to the size of the anode or cathode, followed by an appropriate polarization under a DC field of 3.5 kV mm\u22121 in air atmosphere at ambient temperature for 0.5 h. Finally, the polarized pieces were fully soaked in a liquid electrolyte of 1 mol L\u22121 NaClO4 dissolved in propylene carbonate (PC) with a 5 vol% fluorinated ethylene carbonate (FEC) additive in a glove box over 24 h, yielding the desired BaTiO3-P(VDF-HFP)-NaClO4 piezoelectric gel-electrolyte.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75516, "context": "In 2015, unique graphene-like Co9S8 with a high surface area and hierarchical porosity was first proposed by Nazar's group to afford superior LiPS adsorptivity for high-performance Li\u2013S batteries. The Co9S8/S composite cathode not only manifests up to a factor of 10 increase of cycling stability (0.045% fading per cycle over 1500 cycles at C/2 at a sulfur loading of 1.5 mg cm\u22122) compared to standard porous carbons but also, more importantly, enables a high-loading sulfur electrode with up to 75 wt% sulfur and up to 4.5 mg cm\u22122 areal sulfur loading. First-principles calculations and spectroscopic studies consistently demonstrate that a synergistic dual interaction based on Sn2\u2212 \u2192 Co\u03b4+ and Li+ \u2192 S\u03b4\u2212 exists between the metal sulfide-based host material and LiPSs. In particular, it is revealed that the nature of the crystallographic surface plays a very crucial role. The binding energy of 2.22 eV for Li2S2 on the (002) surface (Co/S = 1:4) increases to 3.24 eV for the (202) surface (Co/S = 5:4) and further to 6.06 eV for the purely Co-terminated (008) plane. This finding enables a better understanding of the interaction mechanism for metal sulfides and provides guidance for fabricating host materials with preferred crystal faces, but unfortunately, the mechanism by which the polar surface accelerates LiPS redox has not been clearly revealed yet. Soon after, Yuan et al. demonstrated that simply introducing half-metallic CoS2 microparticles into graphene electrodes largely amplified the electrochemical current response and reduced charge transfer resistance in LiPS symmetrical cells. More importantly, it is found that CoS2 serves as a mediator to provide strong CoS2\u2013polysulfide interaction and to facilitate the liquid\u2013liquid redox of polysulfides, further affecting the correlated liquid\u2013solid transformation, viz., the prior formation of Li2S nuclei. With a sulfur loading of 0.4 mg cm\u22122, a high initial capacity of 1368 mA h g\u22121 at 0.5C, an increase of 10% in energy efficiency, and a low decay rate of 0.034% per cycle for 2000 cycles at 2.0C are realized through the incorporation of mechanically milled CoS2 with a low specific surface area. These observations suggest that manipulating the redox reactivity of polysulfides upon a conducting surface is a more effective strategy for improving the Li\u2013S battery performance, in comparison to tuning the dissolvability and transport behavior of polysulfides in aprotic electrolytes. Given that the metal sulfide herein employed is in the bulk form, therefore, the performance enhancement can be further achieved by optimizing its structure and properties, including engineering the crystal facets to mediate the adsorbate\u2013adsorbent interaction, reducing the dimension to maximize the exposed polar surface and introducing a strong coupling effect between substrates and supported metal sulfides for intriguing modulation of material properties.", "question": "What's the cathode?", "answer": "Co9S8/S composite", "answer_start": 201}
{"document_id": 75516, "context": "In 2015, unique graphene-like Co9S8 with a high surface area and hierarchical porosity was first proposed by Nazar's group to afford superior LiPS adsorptivity for high-performance Li\u2013S batteries. The Co9S8/S composite cathode not only manifests up to a factor of 10 increase of cycling stability (0.045% fading per cycle over 1500 cycles at C/2 at a sulfur loading of 1.5 mg cm\u22122) compared to standard porous carbons but also, more importantly, enables a high-loading sulfur electrode with up to 75 wt% sulfur and up to 4.5 mg cm\u22122 areal sulfur loading. First-principles calculations and spectroscopic studies consistently demonstrate that a synergistic dual interaction based on Sn2\u2212 \u2192 Co\u03b4+ and Li+ \u2192 S\u03b4\u2212 exists between the metal sulfide-based host material and LiPSs. In particular, it is revealed that the nature of the crystallographic surface plays a very crucial role. The binding energy of 2.22 eV for Li2S2 on the (002) surface (Co/S = 1:4) increases to 3.24 eV for the (202) surface (Co/S = 5:4) and further to 6.06 eV for the purely Co-terminated (008) plane. This finding enables a better understanding of the interaction mechanism for metal sulfides and provides guidance for fabricating host materials with preferred crystal faces, but unfortunately, the mechanism by which the polar surface accelerates LiPS redox has not been clearly revealed yet. Soon after, Yuan et al. demonstrated that simply introducing half-metallic CoS2 microparticles into graphene electrodes largely amplified the electrochemical current response and reduced charge transfer resistance in LiPS symmetrical cells. More importantly, it is found that CoS2 serves as a mediator to provide strong CoS2\u2013polysulfide interaction and to facilitate the liquid\u2013liquid redox of polysulfides, further affecting the correlated liquid\u2013solid transformation, viz., the prior formation of Li2S nuclei. With a sulfur loading of 0.4 mg cm\u22122, a high initial capacity of 1368 mA h g\u22121 at 0.5C, an increase of 10% in energy efficiency, and a low decay rate of 0.034% per cycle for 2000 cycles at 2.0C are realized through the incorporation of mechanically milled CoS2 with a low specific surface area. These observations suggest that manipulating the redox reactivity of polysulfides upon a conducting surface is a more effective strategy for improving the Li\u2013S battery performance, in comparison to tuning the dissolvability and transport behavior of polysulfides in aprotic electrolytes. Given that the metal sulfide herein employed is in the bulk form, therefore, the performance enhancement can be further achieved by optimizing its structure and properties, including engineering the crystal facets to mediate the adsorbate\u2013adsorbent interaction, reducing the dimension to maximize the exposed polar surface and introducing a strong coupling effect between substrates and supported metal sulfides for intriguing modulation of material properties.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75521, "context": "The Mg/Ti dual dopants also enhance the surface stability even upon deep electrochemical delithiation. Here we found that ex situ soft XAS surface analysis may provide misleading results if the charged electrodes are not handled properly. In principle, Ni should experience oxidation during charging and reduction during discharging. However, due to the cathode\u2013electrolyte parasitic reaction, the surface nickel oxidation state at various charge/discharge states were lower than that of the bulk (Fig. S9\u2020). Another phenomenon that we constantly observe is that the Ni oxidation states for the charged samples were lower than that at the pristine state in both the TEY and FY modes (Fig. S9\u2020), which is counterintuitive. We believe that this might be due to the thermodynamically unstable Ni4+ continually reacting with the electrolyte during the cell teardown and subsequent sample handling. Thus, eliminating the cell resting time and removing the residual electrolyte are critical for maintaining the true Ni oxidation states for soft XAS analysis. We found that the best practice is to dissemble the cell and rinse the electrode immediately after the cell has reached the designated state of charge. This practice is particularly important for the charged electrodes. Here we rinsed the cycled electrode in an Ar filled glove box immediately after the cells were charged to 4.4 V vs. Li/Li+. The LiNiO2 delivered a higher charge capacity at this upper cutoff voltage than the Mg/Ti\u2013LiNiO2 (Fig. S10\u2020). If the surface was stable at the charged state, the Ni oxidation state at the surface should not exhibit significant difference in these two electrodes, because the charge capacity only differed by 22 mA h g\u22121 (i.e., the Ni oxidation state differed by 0.08). However, we found drastic differences between these electrodes, as explained below. The Ni L3-right/left peak ratios were averaged from three electrodes at the charged state. A significantly higher L3-right/left peak ratio in both FY and TEY modes was found in the Mg/Ti\u2013LiNiO2 sample than that in the LiNiO2 sample (Fig. 4d), indicating enhanced surface stability of the Mg/Ti\u2013LiNiO2 sample in the charged state. Moreover, the low L3-right/left peak ratio in the FY mode of the LiNiO2 electrodes also suggests that the surface reaction induced Ni reduction extended to the deep subsurface. The direct comparison between NMC622 and NMC811 (Fig. S11\u2020) further supports that a higher nickel content results in more surface instability, which can potentially complicate the state of charge assessment using the surface sensitive soft XAS technique. As more studies have made use of the soft XAS technique for analyzing the surface chemistry of battery materials, our results clearly demonstrate that caution is needed when interpreting the data. Although the synchrotron characterization is not highly accessible, other surface-sensitive characterization methods, e.g., XPS, IR, Raman, TEM, ToF-SIMS, also encounter the similar challenges when preparing/handling samples. To improve the data representativeness, the effective error analysis, based on repeated measurements, is recommended.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75517, "context": "As benchmark inorganic cathodes, we selected a number of materials for non-aqueous cells which, according to the reviews and to the best of our knowledge, are superior in terms of voltage, specific energy/power or cycling stability and are attributed to various material families (hexacyanoferrates, layered oxides, polyanionic compounds, and conversion-type cathodes). The list of benchmarks includes KVPO4F, K2[(VOHPO4)2(C2O4)] (KVPCO), K1.75Mn[Fe(CN)6]\u00b70.16H2O (KMHCF), Fe[Fe(CN)6] (FeHCF), K1.81Ni[Fe(CN)6]0.97\u00b70.086H2O (KNHCF), K0.7Mn0.5Fe0.5O2 (KMFO), K0.51V2O5 and K0.42V2O5\u00b70.25H2O (KVO), and sulfur (S).", "question": "What's the cathode?", "answer": "hexacyanoferrates, layered oxides, polyanionic compounds, and conversion-type", "answer_start": 281}
{"document_id": 75517, "context": "As benchmark inorganic cathodes, we selected a number of materials for non-aqueous cells which, according to the reviews and to the best of our knowledge, are superior in terms of voltage, specific energy/power or cycling stability and are attributed to various material families (hexacyanoferrates, layered oxides, polyanionic compounds, and conversion-type cathodes). The list of benchmarks includes KVPO4F, K2[(VOHPO4)2(C2O4)] (KVPCO), K1.75Mn[Fe(CN)6]\u00b70.16H2O (KMHCF), Fe[Fe(CN)6] (FeHCF), K1.81Ni[Fe(CN)6]0.97\u00b70.086H2O (KNHCF), K0.7Mn0.5Fe0.5O2 (KMFO), K0.51V2O5 and K0.42V2O5\u00b70.25H2O (KVO), and sulfur (S).", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75527, "context": "The cathodes were prepared by mixing 80 wt% active materials, 10 wt% acetylene black and 10 wt% polyvinylidene fluoride (PVDF) binder with N-methyl-2-pyrrolidone (NMP) as the solvent. The mixture was coated on aluminum foil, pressed at 20 MPa, and dried at 120 \u00b0C in air for 2 h. The 2025 coin-type cells, consisting of the as-prepared cathode, Li metal as the anode and Celgard 2325 as the separator, were assembled in an argon-filled glove box. The electrolyte was 1 M LiPF6 dissolved in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (volume ratio 3:7). All cells were cycled between 2.0 and 4.8 V (versus Li/Li+) at a current density of 20 mA g\u22121 at room temperature on Land CT 2001A battery testers unless otherwise defined. The electrochemical impedance spectroscopy (EIS) measurements were performed from 100 kHz to 10 mHz with an amplitude of 10 mV using a multichannel potentiostat (PARSTAT MC).", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75532, "context": "In the context of voltage hysteresis, \u2018charge-averaged\u2019 discharge (Vdischarge), charge (Vcharge), and net-average (viz., further average of Vdischarge and Vcharge) voltages (as true average voltages) for the \u2018control\u2019 and fully Ti-substituted (for Mn-ion) Na-TM-oxide cathodes were estimated, as per the following relations, and presented in Fig. 4 as variations with cycle number.", "question": "What's the cathode?", "answer": "Na-TM-oxide", "answer_start": 256}
{"document_id": 75537, "context": "In terms of anode fabrication, TiO2/C@NPSC-x was mixed sufficiently with conductive carbon and sodium carboxymethylated cellulose (CMC-Na) to form a uniform slurry (weight ratio: 7:2:1). Then, the Cu foil coated by the slurry was dried in a vacuum oven at 110 \u00b0C overnight. The anode electrodes for ex situ XRD tests were fabricated by coating the active materials/CMC-Na (weight ratio: 9:1) slurry on an Al current collector. For cathode electrodes, the home-made activated carbon (ZDPC), conductive carbon and PTFE were blended evenly in deionized water (weight ratio: 90:5:5) and painted on carbon-coated Al foil. The loading weight of each electrode was about 1.0 mg cm\u22122. Then, coin-type CR2032 cells were constructed inside a glove box filled with Ar gas. The electrolyte was 0.8 M KPF6 in DEC and EC (1:1, v/v). The separator was glass fibers. Fresh potassium foil served as the counter electrode. Before construction of the PIHC device, the TiO2/C@NPSC-700 anode was pre-activated at 0.1 A g\u22121 for 10 cycles.", "question": "What's the cathode?", "answer": " carbon (ZDPC)", "answer_start": 474}
{"document_id": 75542, "context": "Fig. 4d shows the comparison of the rate performances and coulombic efficiencies of the three types of cathodes under different current densities (0.1, 0.2, 0.5, 1.0, and 2.0C). All three cathodes show a coulombic efficiency over 98%, which could be due to the highly conductive CNF skeletons. And, with increasing the current density from 0.1C to 2.0C, the CNF@V2S3/S cathodes can retain a specific capacitance of 922 mA h g\u22121 (78.9% of the initial value), which is much higher than those of VS2-based LSBs. However, the CNF@VO0.9/S and CNF/S cathodes can retain 390 mA h g\u22121 (55.1%) and 592 mA h g\u22121 (68.8%). Here, to gain better understanding of the effect of V2S3 on the rate performances of cathodes, the in situ reaction resistances were first derived from the charge/discharge curves (see the ESI for details\u2020). As shown in Fig. 4e, the reaction resistances of all three cathodes increase with the increasing specific capacity, which is caused by the low conductivity of intermediate LiPSs. Compared to the CNF@VO0.9/S and CNF/S cathodes, the CNF@V2S3/S ones show a much lower reaction resistance along the whole electrochemical processes. And similar results can also be obtained from Electrochemical Impedance Spectroscopy (EIS) spectra (Fig. S14\u2020). This decrease in resistances often leads to fast redox kinetics on the CNF@V2S3/S cathodes. Besides, galvanostatic intermittent titration technique (GITT) tests were further carried out to further study the origins for fast transfer kinetics of CNF@V2S3/S cathodes (Fig. S15\u2020). The diffusivities of Li ions between the cathode and electrolyte were estimated, as listed in Table S2.\u2020 The diffusion coefficient of Li+ ions in the CNF@V2S3/S/electrolyte system is 2.857 \u00d7 10\u22126 cm2 s\u22121, which is much higher than those of CNF@VO0.9/S and CNF/S ones (1.554 \u00d7 10\u22127 and 1.645 \u00d7 10\u22127 cm2 s\u22121) in this work. This greatly improved diffusivities of Li ions would result in the high specific capacity and the high rate capability of CNF@V2S3/S cathodes. Also, a similar conclusion can be obtained from EIS spectra in the low-frequency region (Fig. S14\u2020). It can be seen that the curve slope of CNF@V2S3/S cathodes is much larger than those of the CNF@VO0.9/S and CNF/S ones (Table S3\u2020).", "question": "What's the cathode?", "answer": "CNF@V2S3/S", "answer_start": 358}
{"document_id": 75542, "context": "Fig. 4d shows the comparison of the rate performances and coulombic efficiencies of the three types of cathodes under different current densities (0.1, 0.2, 0.5, 1.0, and 2.0C). All three cathodes show a coulombic efficiency over 98%, which could be due to the highly conductive CNF skeletons. And, with increasing the current density from 0.1C to 2.0C, the CNF@V2S3/S cathodes can retain a specific capacitance of 922 mA h g\u22121 (78.9% of the initial value), which is much higher than those of VS2-based LSBs. However, the CNF@VO0.9/S and CNF/S cathodes can retain 390 mA h g\u22121 (55.1%) and 592 mA h g\u22121 (68.8%). Here, to gain better understanding of the effect of V2S3 on the rate performances of cathodes, the in situ reaction resistances were first derived from the charge/discharge curves (see the ESI for details\u2020). As shown in Fig. 4e, the reaction resistances of all three cathodes increase with the increasing specific capacity, which is caused by the low conductivity of intermediate LiPSs. Compared to the CNF@VO0.9/S and CNF/S cathodes, the CNF@V2S3/S ones show a much lower reaction resistance along the whole electrochemical processes. And similar results can also be obtained from Electrochemical Impedance Spectroscopy (EIS) spectra (Fig. S14\u2020). This decrease in resistances often leads to fast redox kinetics on the CNF@V2S3/S cathodes. Besides, galvanostatic intermittent titration technique (GITT) tests were further carried out to further study the origins for fast transfer kinetics of CNF@V2S3/S cathodes (Fig. S15\u2020). The diffusivities of Li ions between the cathode and electrolyte were estimated, as listed in Table S2.\u2020 The diffusion coefficient of Li+ ions in the CNF@V2S3/S/electrolyte system is 2.857 \u00d7 10\u22126 cm2 s\u22121, which is much higher than those of CNF@VO0.9/S and CNF/S ones (1.554 \u00d7 10\u22127 and 1.645 \u00d7 10\u22127 cm2 s\u22121) in this work. This greatly improved diffusivities of Li ions would result in the high specific capacity and the high rate capability of CNF@V2S3/S cathodes. Also, a similar conclusion can be obtained from EIS spectra in the low-frequency region (Fig. S14\u2020). It can be seen that the curve slope of CNF@V2S3/S cathodes is much larger than those of the CNF@VO0.9/S and CNF/S ones (Table S3\u2020).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75542, "context": "Fig. 4d shows the comparison of the rate performances and coulombic efficiencies of the three types of cathodes under different current densities (0.1, 0.2, 0.5, 1.0, and 2.0C). All three cathodes show a coulombic efficiency over 98%, which could be due to the highly conductive CNF skeletons. And, with increasing the current density from 0.1C to 2.0C, the CNF@V2S3/S cathodes can retain a specific capacitance of 922 mA h g\u22121 (78.9% of the initial value), which is much higher than those of VS2-based LSBs. However, the CNF@VO0.9/S and CNF/S cathodes can retain 390 mA h g\u22121 (55.1%) and 592 mA h g\u22121 (68.8%). Here, to gain better understanding of the effect of V2S3 on the rate performances of cathodes, the in situ reaction resistances were first derived from the charge/discharge curves (see the ESI for details\u2020). As shown in Fig. 4e, the reaction resistances of all three cathodes increase with the increasing specific capacity, which is caused by the low conductivity of intermediate LiPSs. Compared to the CNF@VO0.9/S and CNF/S cathodes, the CNF@V2S3/S ones show a much lower reaction resistance along the whole electrochemical processes. And similar results can also be obtained from Electrochemical Impedance Spectroscopy (EIS) spectra (Fig. S14\u2020). This decrease in resistances often leads to fast redox kinetics on the CNF@V2S3/S cathodes. Besides, galvanostatic intermittent titration technique (GITT) tests were further carried out to further study the origins for fast transfer kinetics of CNF@V2S3/S cathodes (Fig. S15\u2020). The diffusivities of Li ions between the cathode and electrolyte were estimated, as listed in Table S2.\u2020 The diffusion coefficient of Li+ ions in the CNF@V2S3/S/electrolyte system is 2.857 \u00d7 10\u22126 cm2 s\u22121, which is much higher than those of CNF@VO0.9/S and CNF/S ones (1.554 \u00d7 10\u22127 and 1.645 \u00d7 10\u22127 cm2 s\u22121) in this work. This greatly improved diffusivities of Li ions would result in the high specific capacity and the high rate capability of CNF@V2S3/S cathodes. Also, a similar conclusion can be obtained from EIS spectra in the low-frequency region (Fig. S14\u2020). It can be seen that the curve slope of CNF@V2S3/S cathodes is much larger than those of the CNF@VO0.9/S and CNF/S ones (Table S3\u2020).", "question": "What's the cathode?", "answer": "CNF@VO0.9/S and CNF/S", "answer_start": 522}
{"document_id": 75525, "context": "Gas diffusion electrodes (GDEs) were fabricated by spraying a catalyst ink made from polynorbonene tetrablock copolymer powder ionomers (GT32 and GT73) and Pt-based electrocatalysts onto Toray TGP-H-060 gas diffusion layers (GDLs) with 5% PTFE. Commercially available 40% Pt/C (Alfa Aesar HiSPEC 4000, Pt nominally 40% wt, supported on Vulcan XC-72R carbon) was used at the cathode and 60% Pt\u2013Ru/C (Alfa Aesar HiSPEC 10000, Pt nominally 40 wt%, and Ru, nominally 20 wt%, supported on Vulcan XC-72R carbon) was used as the anode. The detailed procedure for ink formulation and GDE fabrication has been previously reported, though a brief description is provided below.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75529, "context": "Surface modification using some metal oxides is an appropriate approach to overcome such critical drawbacks of LMO. Metal oxides, such as Ta2O5, ZrO2, Al2O3, ZnO, MgO, and TiO2, have been used as coating layers for LMO cathode material powders. The coating layer minimizes direct contact between the cathode and the electrolyte solution, avoids unwanted interfacial reactions, and thus improves the structural stability and phase transitions. To some extent, these coating films can also improve the cycling performance of the material. Nevertheless, the reported high surface coating using metal oxides usually results in agglomerated nanoparticles and leads to increased resistance. Furthermore, the modest improvement could be a result of increased interfacial resistance due to the insulating nature of surface coating layers.", "question": "What's the cathode?", "answer": "LMO ", "answer_start": 215}
{"document_id": 75539, "context": "Moreover, the formation of metal sulfides with a non-crystalline structure also reveals enhanced adsorption/bonding of LiPSs owing to abundant defects and dangling bonds. For example, amorphous TiS4 has been successfully prepared by Sakuda et al. through a mechanical milling process using crystalline TiS2, sulfur, and acetylene black. When used as the cathode in a Li\u2013S battery, the dissolution of LiPSs into the electrolyte is significantly suppressed because amorphization reduces the symmetry of the lattice, leading to the possibility of overlapping electron clouds between sulfur and titanium atoms, resulting in chemical bonding between the elements. Liu et al. reported the synthesis of a S@amorphous NiS2 composite via a coprecipitation reaction using Na2S8 and NiCl2 ethanol solution. Here the soluble sulfide ions can permeate into the loose amorphous structure, and thus the S particle would nucleate and grow in the inner space of NiS2, ensuing the high immobilization of S species. Very recently, Yu et al. meticulously designed hollow-amorphous N-doped carbon/MoS3 nanoboxes (NC/MoS3 NBs) as an advanced sulfur host for Li\u2013S batteries. In a typical synthesis, crystalline \u03b1-Fe2O3 nanocubes are first coated with a layer of polydopamine, which are then calcined in a N2 atmosphere and etched in HCl solution to obtain N-doped carbon (NC) shells and hollow NC nanoboxes, respectively. Finally, the NC/MoS3 NB host is prepared through heterogeneous nucleation using CTAB as the surfactant and (NH4)2MoS4 as the precursor. Here, the amorphous MoS3 with unsaturated coordination Mo and electron-rich S not only has strong binding capability to LiPSs but also exhibits a catalytic effect on polysulfide conversion, which are verified by both experimental investigations and theoretical calculations. More interestingly, this synthesis strategy can be generalized to fabricate other amorphous metal chalcogenides nanoboxes such as CoSx and WSx, which is also promising to be applied in the fields of energy storage and conversion.", "question": "What's the cathode?", "answer": "LiPSs ", "answer_start": 400}
{"document_id": 75539, "context": "Moreover, the formation of metal sulfides with a non-crystalline structure also reveals enhanced adsorption/bonding of LiPSs owing to abundant defects and dangling bonds. For example, amorphous TiS4 has been successfully prepared by Sakuda et al. through a mechanical milling process using crystalline TiS2, sulfur, and acetylene black. When used as the cathode in a Li\u2013S battery, the dissolution of LiPSs into the electrolyte is significantly suppressed because amorphization reduces the symmetry of the lattice, leading to the possibility of overlapping electron clouds between sulfur and titanium atoms, resulting in chemical bonding between the elements. Liu et al. reported the synthesis of a S@amorphous NiS2 composite via a coprecipitation reaction using Na2S8 and NiCl2 ethanol solution. Here the soluble sulfide ions can permeate into the loose amorphous structure, and thus the S particle would nucleate and grow in the inner space of NiS2, ensuing the high immobilization of S species. Very recently, Yu et al. meticulously designed hollow-amorphous N-doped carbon/MoS3 nanoboxes (NC/MoS3 NBs) as an advanced sulfur host for Li\u2013S batteries. In a typical synthesis, crystalline \u03b1-Fe2O3 nanocubes are first coated with a layer of polydopamine, which are then calcined in a N2 atmosphere and etched in HCl solution to obtain N-doped carbon (NC) shells and hollow NC nanoboxes, respectively. Finally, the NC/MoS3 NB host is prepared through heterogeneous nucleation using CTAB as the surfactant and (NH4)2MoS4 as the precursor. Here, the amorphous MoS3 with unsaturated coordination Mo and electron-rich S not only has strong binding capability to LiPSs but also exhibits a catalytic effect on polysulfide conversion, which are verified by both experimental investigations and theoretical calculations. More interestingly, this synthesis strategy can be generalized to fabricate other amorphous metal chalcogenides nanoboxes such as CoSx and WSx, which is also promising to be applied in the fields of energy storage and conversion.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75544, "context": "To further analyze the electrochemical difference between the pristine and treated LMO, the initial cycle curves for the two samples are plotted together in Fig. 2a. For pristine LMO, the plateau above 4.5 V appears as the typical behavior of the Li-rich cathode, which corresponds to the delithiation, charge compensation and oxygen release process. Upon discharge, an S-shaped curve was observed with a discharge capacity of around 200 mA h g\u22121. Interestingly, the characteristic charge plateau (above 4.5 V) was shortened in the T-LMO sample. Simultaneously, plateaus appeared at around 4.1 V for the charged state and 4.0 V/2.8 V for the discharged state, which can be seen clearly in the dQ/dV plots (Fig. 2b), indicating that the spinel phase may exist in T-LMO.", "question": "What's the cathode?", "answer": "Li-rich", "answer_start": 247}
{"document_id": 75520, "context": "Metal\u2013air batteries with high energy density have emerged as key players in the energy storage sector. They operate on two underlying processes, namely, the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). It provides the impetus to design efficient, earth-abundant and economic bifunctional electrocatalysts vis-\u00e0-vis precious metal-based catalysts. In this perspective, a few polyanionic battery insertion materials have been reported as potential electrocatalysts. In the current work, metal fluorophosphate (Na2MPO4F, M = Fe/Co/Mn) family of sodium insertion materials have been shown as a new class of bifunctional electrocatalysts with robust structural stability. In particular, Na2CoPO4F was found to exhibit superior catalytic performance with an onset potential of 0.903 V (vs. RHE) for the ORR and an overpotential of 380 mV (vs. RHE) for the OER. The underlying mechanism and kinetics were explored using ab initio computational studies. Overall, polyanionic transition metal fluorophosphates were explored for the first time as bifunctional electrocatalysts capable of working as potential cathode materials in hybrid metal\u2013air batteries.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75528, "context": "Imide-functionalized small molecules are represented by 3,4,9,10-perylene-tetracarboxylic diimide (PTCDI 10), recently proposed by Fan et al. It has lower solubility compared to PTCDA, which should have improved its cycling stability. Nevertheless, with 1 M and 3 M KFSI solutions in EC:DMC, rapid capacity fading associated with the material dissolution was observed. The cathode dissolution was suppressed by using 5 M KFSI in EC:DMC, which ensured \u223c0% capacity decay over 100 cycles at 100 mA g\u22121 and \u223c90% retention after 600 cycles at 4 A g\u22121. The reported Qm at 100 mA g\u22121 was 157 mA h g\u22121, which is higher than the theoretical value of 137 mA h g\u22121; the additional capacity (\u223c27 mA h g\u22121) originated from the carbon additive. Impressive capacities of 137 and 80 mA h g\u22121 were observed at 1 and 10 A g\u22121, respectively. The rate performance of PTCDI was reported to be superior compared to PTCDA under the same conditions. PTCDI-based full cells, which had pre-potassiated graphite as the anode, delivered a Qm of 140 and 80 mA h g\u22121 at 50 and 500 mA g\u22121, respectively. The output voltage was 2 V and \u223c50% of the capacity retained after 500 cycles at 500 mA g\u22121.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75535, "context": "Later, Wang et al. published a similar study, using annealed PTCDA as the anode material and 30 M KFSI aqueous solution as the electrolyte. The reversible capacity of PTCDA reached 134 mA h g\u22121 at 0.2 A g\u22121. Decent rate and cycling capabilities were demonstrated. A full cell with potassium iron(II) hexacyanoferrate as the cathode delivered 39 mA h g\u22121 based on the combined mass of the electrodes, and it was almost constant up to 4 A g\u22121 current density. The capacity retention of the full cell was 89% after 1000 cycles at 2 A g\u22121.", "question": "What's the cathode?", "answer": "potassium iron(II) hexacyanoferrate", "answer_start": 281}
{"document_id": 75535, "context": "Later, Wang et al. published a similar study, using annealed PTCDA as the anode material and 30 M KFSI aqueous solution as the electrolyte. The reversible capacity of PTCDA reached 134 mA h g\u22121 at 0.2 A g\u22121. Decent rate and cycling capabilities were demonstrated. A full cell with potassium iron(II) hexacyanoferrate as the cathode delivered 39 mA h g\u22121 based on the combined mass of the electrodes, and it was almost constant up to 4 A g\u22121 current density. The capacity retention of the full cell was 89% after 1000 cycles at 2 A g\u22121.", "question": "What's the anode?", "answer": "PTCDA", "answer_start": 61}
{"document_id": 75535, "context": "Later, Wang et al. published a similar study, using annealed PTCDA as the anode material and 30 M KFSI aqueous solution as the electrolyte. The reversible capacity of PTCDA reached 134 mA h g\u22121 at 0.2 A g\u22121. Decent rate and cycling capabilities were demonstrated. A full cell with potassium iron(II) hexacyanoferrate as the cathode delivered 39 mA h g\u22121 based on the combined mass of the electrodes, and it was almost constant up to 4 A g\u22121 current density. The capacity retention of the full cell was 89% after 1000 cycles at 2 A g\u22121.", "question": "What's the electrolyte?", "answer": "30 M KFSI aqueous solution", "answer_start": 93}
{"document_id": 75538, "context": "Determined by a continuous discharging test over 27 h, the recorded specific capacity of the battery with the CNT@CNP catalyst is 846.7 mA h gZn\u22121, and the relative energy density is 1059.92 mW h gZn\u22121 at an average voltage of 1.2 V, as shown in Fig. 7(d). These outcomes are better than those of most current Fe\u2013N\u2013C catalysts shown in Table 2. Moreover, the rechargeable performance of the battery, equipped with the CNT@CNP catalyst and commercial 20 wt% IrO2 on carbon paper as an air cathode, has been tested by us. As observed in Fig. 7(e), the novel battery shows remarkably improved ORR and OER properties, compared with the reference of the battery equipped with the commercial Pt/C and IrO2 counterpart. At a constant current density of 20 mA cm\u22122 for 10 h, the cycling of charge and discharge reaches 2 times with respect to the reference battery, as shown in Fig. 7(f). The battery almost maintains a stable discharge potential of 0.83 V and a recharge voltage of 2.25 V even after 60 cycles, which is much better than that of the reference battery shown in Fig. 7(f). So, the synthesized catalyst shows a very good power density in comparison with the corresponding results available in the literature shown in Table 2. Therefore, the optimal catalytic performance of the carbon interpenetrating networks may be attributed to the formation of abundant edge Fe\u2013Nx moieties as active sites at the boundaries and interfaces in the CNT@CNP composites with a smart structure. If so, developing Fe\u2013N\u2013C with interpenetrating network structures may be major breakthroughs of non-PGM materials serving as next-generation catalysts for the ORR.", "question": "What's the cathode?", "answer": "air", "answer_start": 484}
{"document_id": 75543, "context": "Fig. 1c shows the main fabrication processes of high-performance LSBs based on CNF@V2S3/S composite cathodes. Electrospun nanoscale fibrous skeletons were often used as conductive substrates for active materials in energy-storage devices. During the annealing under Ar, many V atoms were forced out to the surface of electrospun nanofibers under the Kirkendall effect, and formed into VO0.9 nanocrystals. Then, the formed VO0.9 nanocrystals will further be vulcanized into V2S3 nanocrystals with an ultralow rate during the vulcanization reaction in a S/Ar environment. As a result, many V2S3 nanocrystals are stably connected to the surface of CNFs, which benefit the transport of electrons through the CNF/V2S3 composites. And these tiny V2S3 nanocrystals can also show a high specific surface area and a high catalytic activity, which can benefit the chemisorption and the transformation of sulfur species during the charge/discharge processes in LSBs.", "question": "What's the cathode?", "answer": "CNF@V2S3/S composite", "answer_start": 79}
{"document_id": 75541, "context": "F-doped h-BNNS were used as the cathode material for magnesium batteries, a potential alternative to Li-ion batteries due to their higher safety and lower cost. It was reported that fluorine can be grafted via a reaction between h-BNNS and fluoroboric acid. Fluorination effectively improves the electrical conductivity of h-BNNS and their electrochemical performance for Mg batteries.", "question": "What's the cathode?", "answer": "F-doped h-BNNS ", "answer_start": 0}
{"document_id": 75551, "context": "Recently, a high energy density (97.6 W h kg\u22121) along with impressive cycling steadiness (73% retention after 5000 cycles at 1 A g\u22121) was reported by Yang et al. for a lithium-ion capacitor fabricated by using PAN/hydrothermal-made V3O7\u00b7H2O nanowire derived CNFs/V2O3 hybrids as the anode and commercial activated carbon (AC) as the cathode. Additionally, the prepared CNFs/V2O3 nanocomposites with internal void spaces displayed a high capacity of 569.1 mA h g\u22121 at 0.1 A g\u22121 as well as unexpected rate capability (238.5 mA hg\u22121 at 10.0 A g\u22121) in half-cell tests. By electrospinning a PAN/VO(acac)2 precursor solution, followed by calcination, V\u2013O\u2013C nanocomposites with a specific surface area of 587.9 m2 g\u22121 were obtained. An atomic level dispersion of vanadium within the composite nanofibers enabled the resultant V\u2013O\u2013C nanocomposites to deliver a specific capacitance of 463 F g\u22121 at 1 A g\u22121 with good electronic conductivity and electrolyte penetration. Moreover, the electrochemical properties of V5+ are superior to those of V3+ and V4+ when vanadium oxide-embedded carbon fibers are applied in a supercapacitor. Bai et al. produced CNFs/V2O3, CNFs/VO2\u2013V2O5 and CNFs/V2O5via electrospinning a PAN/VO(acac)2 precursor solution, followed by different calcination processes. The results showed that the electrochemical performance of CNFs/V2O5 is better than that of CNFs/V2O3 and CNFs/VO2\u2013V2O5 when they were applied to SCs. In Tang's work, CNFs/VO/VOx web-like nanocomposites were obtained by electrospinning a polymer-based solution containing PAN, PVP, hybrid vanadium precursors (VO2, V2O5, and VO(acac)2) and DMF, followed by carbonization treatment. The formation of quasi-metallic VO (\u223c102 \u03a9\u22121 cm\u22121) in the CNF enhanced the rate of electron transfer in the web-like electrode. Besides, the well-developed pore structure and rich vanadium redox couples also promoted the rapid ion transfer rate. As a consequence, the SC equipped with symmetric CNFs/VO/VOx electrodes exhibited a specific capacitance of 325.7 F g\u22121 at 1 A g\u22121 with 92% retention at 4 A g\u22121 after 5000 cycles.", "question": "What's the cathode?", "answer": "activated carbon (AC)", "answer_start": 304}
{"document_id": 75556, "context": "Second, the electrode capacity was calculated (eqn (4)) to be 453 mA h g\u22121 and third, by integrating the potential profile (eqn (5)), the gravimetric electrode energy density was estimated to be 570 W h kg\u22121. Both values are here for the organic redox-active part (AQ4), while if we take into account the entire electrode (AQnC72), we arrive at significantly more modest values: 222 mA h g\u22121 and 279 W h kg\u22121 (Table S8\u2020). Neither of these measures are totally fair to be compared with traditional electrodes as we also assume a role as current collector for the graphene. With this caveat, the former measure provides twice the experimentally measured capacity of pure AQ, reported to be 217 mA h g\u22121 ( ) and a theoretical gravimetric energy density comparable to the cathode active materials LiFePO4 (544 W h kg\u22121) and LiMn2O4 (548 W h kg\u22121).", "question": "What's the cathode?", "answer": "LiFePO4 ", "answer_start": 793}
{"document_id": 75550, "context": "During the initial discharge on the cathode:", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75560, "context": "In the last few decades, the demand for batteries has rapidly increased in various application fields. Although rechargeable batteries (such as lithium-ion batteries) have become a focus of attention, primary batteries still occupy a large market share in many civilizations and military applications such as portable power sources, signal lights, and space and ocean exploration. As a result, efforts to develop primary batteries with high energy density, high power density, and low cost have never stopped ever since the invention of volt batteries in 18th century. Especially in recent years, large number of batteries with high energy density have been developed, such as the Zn\u2013O2, Mg\u2013O2, Al\u2013O2, Na\u2013O2, and Li\u2013O2 systems. In addition, primary batteries, such as the currently developed Li\u2013SO2, Li\u2013SOCl2, Li\u2013MnO2, and Li-CFx systems, have also been developed under isolated conditions for applications such as ocean and out space. Primary batteries are usually required to have high energy density, long shelf life, stable discharge voltage, and low self-discharge rate and should be readily available for use. Currently, the Li/MnO2 batteries account for more than 80% share of the lithium primary battery market due to their low cost, high safety, and natural abundance of Li and Mn. Moreover, the Li/MnO2 batteries possess a high practical specific energy of 308 W h kg\u22121 and a long shelf life of about 10 years. However, the application of Li/MnO2 batteries is limited by their poor electrochemical performance at high power output and low temperature, which is ascribed to several issues including low electronic conductivity, low lithium diffusion coefficient, and structural susceptibility of the MnO2 cathode. To address these issues, numerous methods, such as structural design and composite, coating, and metal cation doping, have been studied to optimize the performance of the MnO2 cathode. In addition, to overcome the intrinsic limitations of the current cathode materials, exploring novel cathode materials is a potential strategy for promoting the performance of lithium primary batteries.", "question": "What's the cathode?", "answer": "MnO2 ", "answer_start": 1709}
{"document_id": 75560, "context": "In the last few decades, the demand for batteries has rapidly increased in various application fields. Although rechargeable batteries (such as lithium-ion batteries) have become a focus of attention, primary batteries still occupy a large market share in many civilizations and military applications such as portable power sources, signal lights, and space and ocean exploration. As a result, efforts to develop primary batteries with high energy density, high power density, and low cost have never stopped ever since the invention of volt batteries in 18th century. Especially in recent years, large number of batteries with high energy density have been developed, such as the Zn\u2013O2, Mg\u2013O2, Al\u2013O2, Na\u2013O2, and Li\u2013O2 systems. In addition, primary batteries, such as the currently developed Li\u2013SO2, Li\u2013SOCl2, Li\u2013MnO2, and Li-CFx systems, have also been developed under isolated conditions for applications such as ocean and out space. Primary batteries are usually required to have high energy density, long shelf life, stable discharge voltage, and low self-discharge rate and should be readily available for use. Currently, the Li/MnO2 batteries account for more than 80% share of the lithium primary battery market due to their low cost, high safety, and natural abundance of Li and Mn. Moreover, the Li/MnO2 batteries possess a high practical specific energy of 308 W h kg\u22121 and a long shelf life of about 10 years. However, the application of Li/MnO2 batteries is limited by their poor electrochemical performance at high power output and low temperature, which is ascribed to several issues including low electronic conductivity, low lithium diffusion coefficient, and structural susceptibility of the MnO2 cathode. To address these issues, numerous methods, such as structural design and composite, coating, and metal cation doping, have been studied to optimize the performance of the MnO2 cathode. In addition, to overcome the intrinsic limitations of the current cathode materials, exploring novel cathode materials is a potential strategy for promoting the performance of lithium primary batteries.", "question": "What's the cathode?", "answer": "MnO2 ", "answer_start": 1894}
{"document_id": 75565, "context": "In order to further study the chemisorption of LiPSs on the electrodes, we carried out the visual adsorption experiment of Li2S6 on the CNF@V2S3 cathodes. As shown in Fig. 3g, the dark-yellow colour of Li2S6 solution containing CNF@V2S3 fades in the visible region obviously after 24 h; while the solution containing CNFs, by contrast, almost shows no change in its colour, directly demonstrating that CNF@V2S3 cathodes can anchor LiPSs strongly. Moreover, we also compare the colour change of the polypropylene separators used in the assembled LSBs. As shown in Fig. S6,\u2020 after 100 cycles, the separator in the LSBs based on CNF@V2S3 composites almost retains its own white colour; while that based on CNF@V2S3 and CNFs cathodes show an apparent change in colour from white to light yellow, especially that based on CNFs. These visual comparisons of the change in colour again indicate that the CNF@V2S3 composites could greatly inhibit the shuttling of LiPSs between the electrodes. Furthermore, first-principles simulations based on density functional theory (DFT) have been applied to theoretically study the chemisorption behaviours of LiPSs. Fig. 2h shows the adsorption conformation of LiPSs (Li2Sn: n = 2, 4 and 6) on the (204) plane of V2S3. And the Eads between V2S3 and Li2S/Li2S4/Li2S6 were estimated to be 1.29, 0.81 and 1.02 eV, which are much higher than those values of the Eads between C and LiPSs.", "question": "What's the cathode?", "answer": "CNF@V2S3 ", "answer_start": 136}
{"document_id": 75565, "context": "In order to further study the chemisorption of LiPSs on the electrodes, we carried out the visual adsorption experiment of Li2S6 on the CNF@V2S3 cathodes. As shown in Fig. 3g, the dark-yellow colour of Li2S6 solution containing CNF@V2S3 fades in the visible region obviously after 24 h; while the solution containing CNFs, by contrast, almost shows no change in its colour, directly demonstrating that CNF@V2S3 cathodes can anchor LiPSs strongly. Moreover, we also compare the colour change of the polypropylene separators used in the assembled LSBs. As shown in Fig. S6,\u2020 after 100 cycles, the separator in the LSBs based on CNF@V2S3 composites almost retains its own white colour; while that based on CNF@V2S3 and CNFs cathodes show an apparent change in colour from white to light yellow, especially that based on CNFs. These visual comparisons of the change in colour again indicate that the CNF@V2S3 composites could greatly inhibit the shuttling of LiPSs between the electrodes. Furthermore, first-principles simulations based on density functional theory (DFT) have been applied to theoretically study the chemisorption behaviours of LiPSs. Fig. 2h shows the adsorption conformation of LiPSs (Li2Sn: n = 2, 4 and 6) on the (204) plane of V2S3. And the Eads between V2S3 and Li2S/Li2S4/Li2S6 were estimated to be 1.29, 0.81 and 1.02 eV, which are much higher than those values of the Eads between C and LiPSs.", "question": "What's the cathode?", "answer": "CNF@V2S3 ", "answer_start": 402}
{"document_id": 75568, "context": "In order to understand the relationship between self-discharge and electrolyte composition, the Li/LiV2(PO4)3 batteries were disassembled after one-week storage. The images of the Al current collectors and metallic Li of the disassembled battery are shown in Fig. 2. As shown in Fig. 2a and j, the Al current collector was obviously corroded, and many black precipitates were formed at the edge of the metallic Li electrode with the LPE-EC electrolyte. However, the appearances of the Al current collector and metallic Li electrode of the batteries with the LPE-PC and LPE-PC\u2013LiBOB electrolytes were significantly better, as displayed in Fig. 2b, c, k and l, showing smooth Al current collectors and clean metallic Li surfaces. SEM was performed in order to verify the actual condition of the Al surface. As shown in the SEM images of the Al current collectors (Fig. 2d and g), the surface morphologies of the corroded Al current collector of the battery with the LPE-EC electrolyte displayed a high pit density, whereas those in the case of the batteries with the LPE-PC and LPE-PC\u2013LiBOB electrolytes were smoother. The pits on the Al current collector were probably caused by the electrochemical oxidation of EC at high potentials generates a proton and triggers the chemical corrosion of aluminum foils. Pitting corrosion of the Al current collector can cause serious problems: passivation of cathode materials, increase of electrical resistance, contamination of the electrolyte, and reduction reactions of dissolved Al3+ on the anode side. Thus, the observed black precipitates on the metallic Li electrode could be the Li\u2013Al alloy (LixAl) or a mixture of metallic Li and Li\u2013Al alloy (cathodic: Al \u2192 Al3+ + 3e\u2212; anodic: Al3+ + 3e\u2212 + Li \u2192 LixAl). The growth of precipitates can lead to separator piercing and internal short circuit of a battery, which is responsible for the rapid voltage drop and self-discharge of the Li/LiV2(PO4)3 batteries with the LPE-EC electrolyte (Fig. 1b). SEM images of the surface of the Al current collector of a battery with the LPE-PC and LPE-PC\u2013LiBOB electrolytes after one-week storage are shown in Fig. 2e and h and Fig. 2f and i, respectively. Almost no obvious pitting corrosion was observed on the surfaces of the Al current collectors, confirming the better shelf stabilities of the Li/LiV2(PO4)3 batteries with the LPE-PC and LPE-PC\u2013LiBOB electrolytes than that of the Li/LiV2(PO4)3 battery with the LPE-EC electrolyte (Fig. 1c and d), respectively. Therefore, the electrolyte composition can affect the stability of the current collector. The corrosion of the current collectors is a key reason for the self-discharge behavior of batteries.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75552, "context": "The FIB-SEM tomography and electrochemical testing results together strongly suggest that the severe mechanical degradation is the main cause of the rapid capacity fade in the SSB composite electrode, particularly in later cycles. In current study, the crack development is mostly observed near the cathode/solid electrolyte interface, which suggests that the cathode particle volume change is the origin of the mechanical failure during cycling. Thus, minimizing this mechanical degradation is critical to extending the cycle life of SSBs.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75561, "context": "When used as cathode materials, anhydrides and imides of tetracarboxylic aromatic acids undergo two-electron reversible reduction, as depicted in Scheme 2. The reduction of the remaining carbonyls occurs at low voltages; it is generally considered irreversible, although some data on using these structures as anode materials indicate the opposite (see Section 3.3).", "question": "What's the cathode?", "answer": "anhydrides and imides of tetracarboxylic aromatic acids ", "answer_start": 32}
{"document_id": 75566, "context": "Nowadays, a variety of multifunctional electrocatalysts are being developed while there is still a lack of suitable design to fully realize their multifunctionalities. Here, we propose a general, simple, two-component design of an electrolyser to replace the traditional three-component design for decoupled water splitting. Trifunctional (OER, HER and ORR) electrocatalysts (such as nickel sulfide foams with surface grown N-doped carbon nanotube arrays) are used as the gas evolution electrode to replace both the cathode and the anode, while materials with suitable redox activities (NaTi2(PO4)3 or commercial Ni(OH)2) are used as the relay electrode. In such a design, the H2/O2 evolution can be switched by reversing the current polarity, and the ORR before the HER consumes the residual O2 left in the electrolyser, guaranteeing the high purity (\u223c99.9%) of the as-obtained H2. With NaTi2(PO4)3 as the relay electrode and the nickel sulfide foam as the gas evolution electrode, owing to the high decoupling efficiency of the NaTi2(PO4)3 relay (97%) and the low HER/OER overpotentials of the trifunctional nickel sulfide foam, an energy conversion efficiency of up to 94.3% can be obtained for the as-assembled electrolyser at a current density of 10 mA cm\u22122. When combined with a commercial Si PV module with an efficiency of 14.4%, the as-designed PV-electrolysis system showed a solar-to-hydrogen conversion efficiency of up to 10.4%. Utilization of trifunctional electrocatalysts greatly reduces the complexity of the electrolyser and the overall cost for electrochemical H2 production, and these electrolysers may potentially be used to construct highly competitive water splitting systems for continuous H2 production and green energy harvesting. Our research may also bring new insights into the utilization of multifunctional electrocatalysts in other devices, such as metal\u2013air batteries and fuel cells.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75566, "context": "Nowadays, a variety of multifunctional electrocatalysts are being developed while there is still a lack of suitable design to fully realize their multifunctionalities. Here, we propose a general, simple, two-component design of an electrolyser to replace the traditional three-component design for decoupled water splitting. Trifunctional (OER, HER and ORR) electrocatalysts (such as nickel sulfide foams with surface grown N-doped carbon nanotube arrays) are used as the gas evolution electrode to replace both the cathode and the anode, while materials with suitable redox activities (NaTi2(PO4)3 or commercial Ni(OH)2) are used as the relay electrode. In such a design, the H2/O2 evolution can be switched by reversing the current polarity, and the ORR before the HER consumes the residual O2 left in the electrolyser, guaranteeing the high purity (\u223c99.9%) of the as-obtained H2. With NaTi2(PO4)3 as the relay electrode and the nickel sulfide foam as the gas evolution electrode, owing to the high decoupling efficiency of the NaTi2(PO4)3 relay (97%) and the low HER/OER overpotentials of the trifunctional nickel sulfide foam, an energy conversion efficiency of up to 94.3% can be obtained for the as-assembled electrolyser at a current density of 10 mA cm\u22122. When combined with a commercial Si PV module with an efficiency of 14.4%, the as-designed PV-electrolysis system showed a solar-to-hydrogen conversion efficiency of up to 10.4%. Utilization of trifunctional electrocatalysts greatly reduces the complexity of the electrolyser and the overall cost for electrochemical H2 production, and these electrolysers may potentially be used to construct highly competitive water splitting systems for continuous H2 production and green energy harvesting. Our research may also bring new insights into the utilization of multifunctional electrocatalysts in other devices, such as metal\u2013air batteries and fuel cells.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75571, "context": "Therefore, the above results demonstrate the superior energy/power densities and high efficiency of the DBHF sample, which, based on the above discussions, are associated with the \u201cfiber-in-tube\u201d hierarchical structure, hollow and defective oxide bubbles and conductive and porous carbon network of the DBHF fibers. The combined effects of the features are favourable for the generation of more active sites, superior catalytic activities and enhanced kinetics of the DBHF cathode in the hybrid batteries.", "question": "What's the cathode?", "answer": "DBHF ", "answer_start": 468}
{"document_id": 75558, "context": "To better understand the good cycling stability of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, inductively coupled plasma emission spectrometry-atomic emission spectroscopy (ICP-AES) analysis of the vanadium concentration in the Na\u2013H2O\u2013urea\u2013DMF electrolyte and analysis of electrochemical impedance parameters were carried out before and after cycling. As shown in Fig. 4b and Table S3,\u2020 it is found that the concentration of V-ions in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling is 0.05 \u03bcg mL\u22121. After 50 cycles and after 100 cycles, the concentrations of V-ions in the Na\u2013H2O\u2013urea\u2013DMF electrolyte are 16.65 \u03bcg mL\u22121 and 20.12 \u03bcg mL\u22121, respectively. In 1 M Na2SO4 solution, the concentrations of V-ions are 0.08 \u03bcg mL\u22121, 60.68 \u03bcg mL\u22121 and 72.34 \u03bcg mL\u22121, respectively. Compared to 1 M Na2SO4 solution, the Na\u2013H2O\u2013urea\u2013DMF electrolyte can obviously inhibit the dissolution of the electrode materials. Upon comparison of the V-ion concentrations in NaClO4 solution, Na\u2013H2O\u2013DMF, and Na\u2013H2O\u2013urea electrolyte of the NVP//NTP full cell after 50 cycles (Fig. S14\u2020), it is found that the Na\u2013H2O\u2013urea\u2013DMF electrolyte can suppress the dissolution of V-ions in the charge\u2013discharge process. This result is consistent with the cycling performances of the NVP//NTP full cell in different electrolytes (Fig. S13\u2020). Thus, it can be concluded that the NVP/C cathode is much more stable in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, which is beneficial for the long lifespan of the full cell. Similarly, as illustrated in Fig. S15,\u2020 the NTP anode in the Na\u2013H2O\u2013urea\u2013DMF electrolyte displays high coulombic efficiency and good cycling stability relative to that in 17 M NaClO4 and 1 M Na2SO4 solution.", "question": "What's the cathode?", "answer": "NVP/C", "answer_start": 1344}
{"document_id": 75558, "context": "To better understand the good cycling stability of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, inductively coupled plasma emission spectrometry-atomic emission spectroscopy (ICP-AES) analysis of the vanadium concentration in the Na\u2013H2O\u2013urea\u2013DMF electrolyte and analysis of electrochemical impedance parameters were carried out before and after cycling. As shown in Fig. 4b and Table S3,\u2020 it is found that the concentration of V-ions in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling is 0.05 \u03bcg mL\u22121. After 50 cycles and after 100 cycles, the concentrations of V-ions in the Na\u2013H2O\u2013urea\u2013DMF electrolyte are 16.65 \u03bcg mL\u22121 and 20.12 \u03bcg mL\u22121, respectively. In 1 M Na2SO4 solution, the concentrations of V-ions are 0.08 \u03bcg mL\u22121, 60.68 \u03bcg mL\u22121 and 72.34 \u03bcg mL\u22121, respectively. Compared to 1 M Na2SO4 solution, the Na\u2013H2O\u2013urea\u2013DMF electrolyte can obviously inhibit the dissolution of the electrode materials. Upon comparison of the V-ion concentrations in NaClO4 solution, Na\u2013H2O\u2013DMF, and Na\u2013H2O\u2013urea electrolyte of the NVP//NTP full cell after 50 cycles (Fig. S14\u2020), it is found that the Na\u2013H2O\u2013urea\u2013DMF electrolyte can suppress the dissolution of V-ions in the charge\u2013discharge process. This result is consistent with the cycling performances of the NVP//NTP full cell in different electrolytes (Fig. S13\u2020). Thus, it can be concluded that the NVP/C cathode is much more stable in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, which is beneficial for the long lifespan of the full cell. Similarly, as illustrated in Fig. S15,\u2020 the NTP anode in the Na\u2013H2O\u2013urea\u2013DMF electrolyte displays high coulombic efficiency and good cycling stability relative to that in 17 M NaClO4 and 1 M Na2SO4 solution.", "question": "What's the anode?", "answer": "NTP ", "answer_start": 1518}
{"document_id": 75558, "context": "To better understand the good cycling stability of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, inductively coupled plasma emission spectrometry-atomic emission spectroscopy (ICP-AES) analysis of the vanadium concentration in the Na\u2013H2O\u2013urea\u2013DMF electrolyte and analysis of electrochemical impedance parameters were carried out before and after cycling. As shown in Fig. 4b and Table S3,\u2020 it is found that the concentration of V-ions in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling is 0.05 \u03bcg mL\u22121. After 50 cycles and after 100 cycles, the concentrations of V-ions in the Na\u2013H2O\u2013urea\u2013DMF electrolyte are 16.65 \u03bcg mL\u22121 and 20.12 \u03bcg mL\u22121, respectively. In 1 M Na2SO4 solution, the concentrations of V-ions are 0.08 \u03bcg mL\u22121, 60.68 \u03bcg mL\u22121 and 72.34 \u03bcg mL\u22121, respectively. Compared to 1 M Na2SO4 solution, the Na\u2013H2O\u2013urea\u2013DMF electrolyte can obviously inhibit the dissolution of the electrode materials. Upon comparison of the V-ion concentrations in NaClO4 solution, Na\u2013H2O\u2013DMF, and Na\u2013H2O\u2013urea electrolyte of the NVP//NTP full cell after 50 cycles (Fig. S14\u2020), it is found that the Na\u2013H2O\u2013urea\u2013DMF electrolyte can suppress the dissolution of V-ions in the charge\u2013discharge process. This result is consistent with the cycling performances of the NVP//NTP full cell in different electrolytes (Fig. S13\u2020). Thus, it can be concluded that the NVP/C cathode is much more stable in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, which is beneficial for the long lifespan of the full cell. Similarly, as illustrated in Fig. S15,\u2020 the NTP anode in the Na\u2013H2O\u2013urea\u2013DMF electrolyte displays high coulombic efficiency and good cycling stability relative to that in 17 M NaClO4 and 1 M Na2SO4 solution.", "question": "What's the electrolyte?", "answer": " Na\u2013H2O\u2013urea\u2013DMF", "answer_start": 71}
{"document_id": 75563, "context": "P. M. V. conceived the idea of the nanomesh-based cathodes and their development was supervised by S. P. Z. S. P. Z. developed the method for coating the nanomesh with MnO2 and its thermal activation and performed thermodynamic simulations and electrochemical testing. D. C. contributed to the development of the MnO2 coating, activation of the cathodes with Li citrate and electrochemical testing. D. C. also assisted in the in situ XRD experiments performed by F. Mattelaer in the group of C. Detavernier, University of Ghent. The manuscript was written by S. P. Z. and revised by P. M. V. All authors have given approval to the final version of the manuscript.", "question": "What's the anode?", "answer": "nanomesh-based", "answer_start": 35}
{"document_id": 75570, "context": "Chemical reactions during storage generate electrically insulating carbonate which elevates internal cell resistance and also alters the surface morphology. The electronic and ionic insulation of carbonate induces a sequence of chemical/electrochemical reaction behaviors. For instance, the transformed Lewis base surfaces can react with electrolytic species, generating detrimental species such as HF and gases. Therefore, extra cautions are required when preparing or handling LiNiO2-based materials before the battery assembly (Fig. 1). Herein, we evaluate the battery performance of the LiNiO2 cathode after storage in the dry box (humidity: \u223c30%) and Ar glove box (the water level was \u223c0.5 ppm) for two weeks. Two weeks would be a reasonable time frame between the synthesis of cathode powders and their processing into batteries in the actual manufacturing.", "question": "What's the cathode?", "answer": "LiNiO2 ", "answer_start": 591}
{"document_id": 75554, "context": "However, due to the slow kinetics of both HER at the cathode and UOR at the anode in urea\u2013water electrolysis, electrocatalysts on the electrodes are necessary to speed up the reactions to achieve high energy efficiency. Traditional noble metal catalysts, such as Pt/C, RuO2, or IrO2, can effectively catalyze monolithic electrolysis, but their low abundance and high cost limit their wide application. Therefore, it is necessary to explore efficient non-noble metal electrocatalysts, such as transition metal compounds, transition metal oxides, macrocycles, nitrides, sulfides, phosphides, etc. Among these catalyst materials, the phosphides have been explored most recently, mainly due to their good conductivity and wettability, including MoP, CoP, FeP, and Ni2P. With regard to cost, abundance, catalytic activity, stability and applicable pH range, MoP has been shown to be a promising candidate.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75564, "context": "The UTCNF cathode was prepared via a simple and efficient ultrasonic-treatment strategy. In detail, a piece of pre-cleaned CNF (1 cm \u00d7 3 cm \u00d7 0.15 cm), thoroughly washed with acetone and water, was immersed in 3 M HCl. Next, the solution was transferred to an ultrasonic apparatus and ultrasonicated for 10 min. After the ultrasonic treatment, the CNF was rinsed with distilled water twice and dried at 60 \u00b0C to obtain the UTCNF. The mass loading of the cobalt/nickel composite hydroxide, obtained by comparison of the weight change between UTCNF and CNF, is \u223c6.0 mg cm\u22122.", "question": "What's the cathode?", "answer": "UTCNF ", "answer_start": 4}
{"document_id": 75569, "context": "Lithium\u2013sulfur batteries have low material costs and high energy densities, which have attracted considerable research interest for application in next-generation energy-storage systems. However, the practical applications of Li\u2013S batteries face challenges owing to their poor sulfur utilization, service lifetimes, and rate capability. Recently, great progress has been made in the design, synthesis, and application of micro/nanostructured metal sulfides to address obstacles facing Li\u2013S batteries. This review aims to highlight valuable concepts from the latest reports. Major approaches to improve sulfur cathodes and strategies for preparing metal sulfide-based materials are first summarized with a particular focus on their main functions and useful properties. Then, the electrochemical activities of metal sulfides are classified and their applications in Li\u2013S batteries are introduced to provide a fundamental understanding of the material interactions involved. In parallel, advancements in the use of interlayers, modification of separators, and protection of lithium anodes that involve metal sulfides are surveyed. Finally, special attention is paid to the general design principles, future prospects, and challenges facing metal sulfides for high-energy-density Li\u2013S batteries.", "question": "What's the cathode?", "answer": "sulfur ", "answer_start": 602}
{"document_id": 75567, "context": "The technology of engineering nanostructured materials is usually applied to create numerous active sites, which can significantly improve the electrochemical performance. Recently, the 2D morphology of nanosheet materials with high specific area has been proved to effectively accelerate the electrochemical kinetics between the active materials and the electrolytes, which are therefore supposed to be promising materials for energy storage. Unfortunately, the serious aggregation behavior in 2D materials, derived from the van der Waals forces among individual nanosheets, will decrease the exposed active sites, thus leading to poor conductivity. Carbon cloth (CC) has been known to be an inexpensive substrate/current collector capable of providing continuous pathways for the transport of electrons. Following the above-mentioned discussions, it would be reasonable to believe that an intriguing way of overcoming the above problems is the in situ growth of 2D nanosheet compounds on a flexibly conductive substrate to obtain a free-standing cathode, aiming at achieving good rate capability, high capacity, and energy density simultaneously.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75572, "context": "A carbon nanotube film was used as the oxygen cathode and Li foil with 0.5 mm thickness as the anode for LOBs. A glass fiber separator wetted with a 100 \u03bcL electrolyte composed of 1.0 M LiTFSI in TEGDME was employed to separate the cathode and anode. All assembled cells were measured on a LAND electrochemical testing system at 25 \u00b0C. The cycling test was conducted with the capacity limited at 1000 mA h g\u22121 at a current density of 300 mA g\u22121.", "question": "What's the cathode?", "answer": "oxygen ", "answer_start": 39}
{"document_id": 75572, "context": "A carbon nanotube film was used as the oxygen cathode and Li foil with 0.5 mm thickness as the anode for LOBs. A glass fiber separator wetted with a 100 \u03bcL electrolyte composed of 1.0 M LiTFSI in TEGDME was employed to separate the cathode and anode. All assembled cells were measured on a LAND electrochemical testing system at 25 \u00b0C. The cycling test was conducted with the capacity limited at 1000 mA h g\u22121 at a current density of 300 mA g\u22121.", "question": "What's the anode?", "answer": "Li foil ", "answer_start": 58}
{"document_id": 75577, "context": "Co-free Ni-rich cathode materials, particularly LiNiO2 and its doped analogs, face ongoing challenges as the need for commercialization rises. To address surface instability and its associated phenomena, a systematic and accurate understanding is highly required. In this work, we systematically studied the fragile surfaces of the LiNiO2-based cathode materials, with the goal of identifying how experimental conditions may influence characterization results. We presented the challenges in characterizing and analyzing the surface chemistry of LiNiO2-based materials using two comparative cathodes as a model platform, i.e., LiNiO2 versus Mg/Ti\u2013LiNiO2. The surface lithium residuals are inevitable and highly dependent on various sample storage and handling conditions. Due to the highly reactive surfaces, we found that the sample preparation for electron microscopy and surface-sensitive X-ray analyses greatly influences the final observations, resulting in skewed surface chemistry analytical results. We also provided some recommendations regarding how to obtain representative characterization analyses. Using simple comparisons, we further illustrated the advantages of Mg/Ti dual dopants to enhance the surface structural resistance to many circumstances, while corroborating previously reported observations. However, we found that the surface of Mg/Ti\u2013LiNiO2 material still encounters a series of problems caused by the fragile CEIs at elevated temperatures. Efforts should be devoted towards the development of highly stable CEIs either by cathode surface coating, doping, electrolyte modification or combining multiple strategies.", "question": "What's the cathode?", "answer": "Co-free Ni-rich", "answer_start": 0}
{"document_id": 75577, "context": "Co-free Ni-rich cathode materials, particularly LiNiO2 and its doped analogs, face ongoing challenges as the need for commercialization rises. To address surface instability and its associated phenomena, a systematic and accurate understanding is highly required. In this work, we systematically studied the fragile surfaces of the LiNiO2-based cathode materials, with the goal of identifying how experimental conditions may influence characterization results. We presented the challenges in characterizing and analyzing the surface chemistry of LiNiO2-based materials using two comparative cathodes as a model platform, i.e., LiNiO2 versus Mg/Ti\u2013LiNiO2. The surface lithium residuals are inevitable and highly dependent on various sample storage and handling conditions. Due to the highly reactive surfaces, we found that the sample preparation for electron microscopy and surface-sensitive X-ray analyses greatly influences the final observations, resulting in skewed surface chemistry analytical results. We also provided some recommendations regarding how to obtain representative characterization analyses. Using simple comparisons, we further illustrated the advantages of Mg/Ti dual dopants to enhance the surface structural resistance to many circumstances, while corroborating previously reported observations. However, we found that the surface of Mg/Ti\u2013LiNiO2 material still encounters a series of problems caused by the fragile CEIs at elevated temperatures. Efforts should be devoted towards the development of highly stable CEIs either by cathode surface coating, doping, electrolyte modification or combining multiple strategies.", "question": "What's the cathode?", "answer": "LiNiO2-based", "answer_start": 332}
{"document_id": 75578, "context": "In this paper, MoP and NiCo-LDH are used to synthesize a composite of MoP@NiCo-LDH, which is supported on nickel foam to form a bifunctional composite catalyst (abbreviated as MoP@NiCo-LDH/NF), as shown in Fig. 1. During the synthesis, different electrodeposition times are used to optimize the catalyst's performance toward both UOR and HER. Both instrumental characterization and electrochemical measurements confirm that the composition between MoP and NiCo-LDH as well as their electrodeposition onto the NF surface can increase the material's specific surface area and produce a synergetic effect toward high performance. To validate this bifunctional catalyst, a two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20) with this catalyst on both the anode and the cathode was designed and constructed, and the test results show that this catalyst has better catalytic performance than that of a Pt/C/NF\u2016IrO2/NF electrolyser, where noble metal materials (Pt and IrO2) are used as the catalysts.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75578, "context": "In this paper, MoP and NiCo-LDH are used to synthesize a composite of MoP@NiCo-LDH, which is supported on nickel foam to form a bifunctional composite catalyst (abbreviated as MoP@NiCo-LDH/NF), as shown in Fig. 1. During the synthesis, different electrodeposition times are used to optimize the catalyst's performance toward both UOR and HER. Both instrumental characterization and electrochemical measurements confirm that the composition between MoP and NiCo-LDH as well as their electrodeposition onto the NF surface can increase the material's specific surface area and produce a synergetic effect toward high performance. To validate this bifunctional catalyst, a two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20) with this catalyst on both the anode and the cathode was designed and constructed, and the test results show that this catalyst has better catalytic performance than that of a Pt/C/NF\u2016IrO2/NF electrolyser, where noble metal materials (Pt and IrO2) are used as the catalysts.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75587, "context": "Fig. S3d\u2020 and 4d display cyclic voltammogram (CV) curves obtained using the S-C(PAN) anode with bare LMO and LMO-30 min in the potential range of 1.0\u20133.2 V at a scan rate of 0.1 mV s\u22121, respectively. One peak is observed in both positive and negative scans in both samples. For the LMO-30 min cathode, a more pronounced peak appearing at 2.63 V in the first positive scan is observed and the peak is shifted to 2.45 V in the subsequent cycles. The peak of the negative scan appears at 1.77 V as depicted in Fig. 4d, which shows that PVDF@LGLZNO does not practically involve in the redox reactions of the tested voltage range, thus the composite coating must be stable and did not contribute to the capacity. The large polarization between the peaks in the first and following cycles is due to SPAN activation energy and the SEI formation. This means that more energy is needed to dissociate the sulfur atom from the pyridine-derivative, which is usually termed as the unique activation process of sulfurized polyacrylonitrile.", "question": "What's the cathode?", "answer": "LMO", "answer_start": 282}
{"document_id": 75587, "context": "Fig. S3d\u2020 and 4d display cyclic voltammogram (CV) curves obtained using the S-C(PAN) anode with bare LMO and LMO-30 min in the potential range of 1.0\u20133.2 V at a scan rate of 0.1 mV s\u22121, respectively. One peak is observed in both positive and negative scans in both samples. For the LMO-30 min cathode, a more pronounced peak appearing at 2.63 V in the first positive scan is observed and the peak is shifted to 2.45 V in the subsequent cycles. The peak of the negative scan appears at 1.77 V as depicted in Fig. 4d, which shows that PVDF@LGLZNO does not practically involve in the redox reactions of the tested voltage range, thus the composite coating must be stable and did not contribute to the capacity. The large polarization between the peaks in the first and following cycles is due to SPAN activation energy and the SEI formation. This means that more energy is needed to dissociate the sulfur atom from the pyridine-derivative, which is usually termed as the unique activation process of sulfurized polyacrylonitrile.", "question": "What's the anode?", "answer": "S-C(PAN)", "answer_start": 76}
{"document_id": 75592, "context": "Fig. 3 shows the electrochemical performances of a half-cell in a three-electrode system and a NVP//NTP full cell. As shown in Fig. 3a and b, the NVP half-cell exhibits a pair of redox peaks with good symmetry at 0.68 V and 0.42 V vs. Ag/AgCl, which can be ascribed to the reversible conversion of the V3+/V4+ couple, corresponding to the reversible extraction/insertion of Na+ in the NVP electrode. The half-cell delivers a specific charge and discharge capacity of 110 mA h g\u22121 and 96 mA h g\u22121 in the first cycle, and exhibits good reversibility for the first time. The irreversible charge capacity mainly resulted from the dissolution of the V-ions until the appearance of O2 evolution which was recorded in CV curves. For NTP, a pair of Ti4+/Ti3+ redox peaks at \u22120.55 V and \u22120.82 V vs. Ag/AgCl can be found in the CV curves. As seen in Fig. 3c, the CV curves show that the hydrogen evolution reaction still does not occur when the potential is \u22121.1 V vs. Ag/AgCl, which suggests that the Na\u2013H2O\u2013urea\u2013DMF electrolyte can inhibit the side reaction well. As shown in Fig. 3d, the NTP in the Na\u2013H2O\u2013urea\u2013DMF electrolyte delivers a pristine discharge capacity of 118 mA h g\u22121, concurrently exhibiting a perfect platform and good reversibility, which is better than that of a NTP anode with cationic doping. As shown in Fig. S10 and S11,\u2020 the NTP anode exhibits an impressive cycling stability in a conventional non-aqueous electrolyte. However, the coulombic efficiency and cycling performance of the NVP cathode at 2C in a conventional non-aqueous electrolyte are poor due to the dissolution of V-ions and change of structure.", "question": "What's the cathode?", "answer": "NVP ", "answer_start": 1500}
{"document_id": 75592, "context": "Fig. 3 shows the electrochemical performances of a half-cell in a three-electrode system and a NVP//NTP full cell. As shown in Fig. 3a and b, the NVP half-cell exhibits a pair of redox peaks with good symmetry at 0.68 V and 0.42 V vs. Ag/AgCl, which can be ascribed to the reversible conversion of the V3+/V4+ couple, corresponding to the reversible extraction/insertion of Na+ in the NVP electrode. The half-cell delivers a specific charge and discharge capacity of 110 mA h g\u22121 and 96 mA h g\u22121 in the first cycle, and exhibits good reversibility for the first time. The irreversible charge capacity mainly resulted from the dissolution of the V-ions until the appearance of O2 evolution which was recorded in CV curves. For NTP, a pair of Ti4+/Ti3+ redox peaks at \u22120.55 V and \u22120.82 V vs. Ag/AgCl can be found in the CV curves. As seen in Fig. 3c, the CV curves show that the hydrogen evolution reaction still does not occur when the potential is \u22121.1 V vs. Ag/AgCl, which suggests that the Na\u2013H2O\u2013urea\u2013DMF electrolyte can inhibit the side reaction well. As shown in Fig. 3d, the NTP in the Na\u2013H2O\u2013urea\u2013DMF electrolyte delivers a pristine discharge capacity of 118 mA h g\u22121, concurrently exhibiting a perfect platform and good reversibility, which is better than that of a NTP anode with cationic doping. As shown in Fig. S10 and S11,\u2020 the NTP anode exhibits an impressive cycling stability in a conventional non-aqueous electrolyte. However, the coulombic efficiency and cycling performance of the NVP cathode at 2C in a conventional non-aqueous electrolyte are poor due to the dissolution of V-ions and change of structure.", "question": "What's the anode?", "answer": "NTP ", "answer_start": 1274}
{"document_id": 75592, "context": "Fig. 3 shows the electrochemical performances of a half-cell in a three-electrode system and a NVP//NTP full cell. As shown in Fig. 3a and b, the NVP half-cell exhibits a pair of redox peaks with good symmetry at 0.68 V and 0.42 V vs. Ag/AgCl, which can be ascribed to the reversible conversion of the V3+/V4+ couple, corresponding to the reversible extraction/insertion of Na+ in the NVP electrode. The half-cell delivers a specific charge and discharge capacity of 110 mA h g\u22121 and 96 mA h g\u22121 in the first cycle, and exhibits good reversibility for the first time. The irreversible charge capacity mainly resulted from the dissolution of the V-ions until the appearance of O2 evolution which was recorded in CV curves. For NTP, a pair of Ti4+/Ti3+ redox peaks at \u22120.55 V and \u22120.82 V vs. Ag/AgCl can be found in the CV curves. As seen in Fig. 3c, the CV curves show that the hydrogen evolution reaction still does not occur when the potential is \u22121.1 V vs. Ag/AgCl, which suggests that the Na\u2013H2O\u2013urea\u2013DMF electrolyte can inhibit the side reaction well. As shown in Fig. 3d, the NTP in the Na\u2013H2O\u2013urea\u2013DMF electrolyte delivers a pristine discharge capacity of 118 mA h g\u22121, concurrently exhibiting a perfect platform and good reversibility, which is better than that of a NTP anode with cationic doping. As shown in Fig. S10 and S11,\u2020 the NTP anode exhibits an impressive cycling stability in a conventional non-aqueous electrolyte. However, the coulombic efficiency and cycling performance of the NVP cathode at 2C in a conventional non-aqueous electrolyte are poor due to the dissolution of V-ions and change of structure.", "question": "What's the anode?", "answer": "NTP", "answer_start": 1341}
{"document_id": 75579, "context": "For the operando-XRD measurements self-standing cathode materials were prepared, using Li1.2Mn0.6Ni0.1Co0.1O2 powder, high-conductive carbon (ketjan black, Alfa Aesar, 99.99%) and PVDF (Kynar Flex, Arkema) dissolved in acetone (Poch czda) in a 70:10:20 wt% ratio, respectively. The slurry was spread on glass and dried in air for about 15 minutes at 80 \u00b0C in a glove box overnight as was discussed previously. For the tests, a home-made cell with a Berillium window, adjusted to a PANalytical Empyrean diffractometer, was assembled in an mBraun Unilab argon glovebox, using the same counter electrode and electrolyte as for the CR2032 cells. The operando-XRD measurements were conducted, using the PANalytical Empyrean diffractometer combined with s one-channel Biologic potentiostat/galvanostat with a C/50 current load applied, in the voltage regime of 2.0 V to 4.8 V.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75584, "context": "Our study underlines the importance of gaining deeper insights into the anionic redox activities of Li-rich materials for designing a new cathode material for future LIBs. Promoting the reversible anionic redox contributions while suppressing the irreversible reactions is vital in designing a cathode material with high energy density and good cycling performance. The combined computational/experimental approach presented here can be applied to predict and verify the anionic redox activities in other Li-rich materials to accelerate the discovery of materials with high energy density and good cycling performance.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75589, "context": "In this study, a flexible self-charging sodium-ion full battery (SCSFB) was feasibly designed by employing self-synthesized Na3V2(PO4)3@C as the cathode, commercial hard carbon as the anode, and a flexible BaTiO3-P(VDF-HFP) film immobilized with a liquid electrolyte of NaClO4 as the built-in piezoelectric gel-electrolyte (BaTiO3-P(VDF-HFP)-NaClO4). Owing to the excellent compatibilities of the electrodes, the flexible SCSFB delivers reasonable electrochemical performance including large specific capacity and stable cyclability. Besides, external mechanical energy from the ambient environment can also be simultaneously collected and stored via a persistent self-charging mode, whether with static compression, repeated bending or continuous palm patting. This work paves a feasible way to the achievement of sustainable sodium-ion full batteries with high flexibility and enhanced safety for wearable electronics that come into direct contact with human tissues.", "question": "What's the cathode?", "answer": "Na3V2(PO4)3@C", "answer_start": 124}
{"document_id": 75589, "context": "In this study, a flexible self-charging sodium-ion full battery (SCSFB) was feasibly designed by employing self-synthesized Na3V2(PO4)3@C as the cathode, commercial hard carbon as the anode, and a flexible BaTiO3-P(VDF-HFP) film immobilized with a liquid electrolyte of NaClO4 as the built-in piezoelectric gel-electrolyte (BaTiO3-P(VDF-HFP)-NaClO4). Owing to the excellent compatibilities of the electrodes, the flexible SCSFB delivers reasonable electrochemical performance including large specific capacity and stable cyclability. Besides, external mechanical energy from the ambient environment can also be simultaneously collected and stored via a persistent self-charging mode, whether with static compression, repeated bending or continuous palm patting. This work paves a feasible way to the achievement of sustainable sodium-ion full batteries with high flexibility and enhanced safety for wearable electronics that come into direct contact with human tissues.", "question": "What's the anode?", "answer": "hard carbon", "answer_start": 165}
{"document_id": 75600, "context": "ssZIBs are composed of four components including a cathode, an anode (zinc metal), a solid electrolyte and current collectors. The gel electrolyte is sandwiched between the cathode and anode. Each component has a significant effect on the performance of the whole battery. Currently, various gel electrolytes have been studied and have been applied in ZIBs. However, the performance of ssZIBs is still not comparable with that of the batteries using liquid electrolytes, especially high rate capability, due to the low ionic conductivities of gel electrolytes. To realize high ionic conductivity, an ideal gel electrolyte requires a high-water content and efficient ion migration channels, combined with reasonable mechanical properties. As one of the principal natural polymers, cellulose nanofibers (CNFs) are widely used as a sustainable reinforcing additive in various composites. In addition, the hydrophilic skeleton of CNFs and their three-dimensional fiber network with a large space can help stabilize the channels for charge transportation. Furthermore, due to the abundant hydroxyl groups on the surface of CNFs, it is facile to link the CNFs with polyacrylamide (PAM) molecular chains through hydrogen bonding. The combination of CNFs and PAM can serve as an effective solid electrolyte with good mechanical properties and high ionic conductivity. Due to the high thermal stability of hydrogel polymers, ssBs are also able to operate under both low and high temperature conditions, which is critical for the application of batteries in some harsh environments such as cold/frozen regions and flying airplanes in space.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75600, "context": "ssZIBs are composed of four components including a cathode, an anode (zinc metal), a solid electrolyte and current collectors. The gel electrolyte is sandwiched between the cathode and anode. Each component has a significant effect on the performance of the whole battery. Currently, various gel electrolytes have been studied and have been applied in ZIBs. However, the performance of ssZIBs is still not comparable with that of the batteries using liquid electrolytes, especially high rate capability, due to the low ionic conductivities of gel electrolytes. To realize high ionic conductivity, an ideal gel electrolyte requires a high-water content and efficient ion migration channels, combined with reasonable mechanical properties. As one of the principal natural polymers, cellulose nanofibers (CNFs) are widely used as a sustainable reinforcing additive in various composites. In addition, the hydrophilic skeleton of CNFs and their three-dimensional fiber network with a large space can help stabilize the channels for charge transportation. Furthermore, due to the abundant hydroxyl groups on the surface of CNFs, it is facile to link the CNFs with polyacrylamide (PAM) molecular chains through hydrogen bonding. The combination of CNFs and PAM can serve as an effective solid electrolyte with good mechanical properties and high ionic conductivity. Due to the high thermal stability of hydrogel polymers, ssBs are also able to operate under both low and high temperature conditions, which is critical for the application of batteries in some harsh environments such as cold/frozen regions and flying airplanes in space.", "question": "What's the anode?", "answer": "zinc metal", "answer_start": 70}
{"document_id": 75581, "context": "Recently, we successfully synthesized and deployed a new family of redox shuttle additives, aromatic cyclopropenium salts, for Na-ion batteries under harsh overcharging conditions. The cyclopropenium cation combines the elements of aromaticity and ionicity, leading to superior electrochemical stability and solubility over conventional neutral shuttle molecules. Together with the other enlightening studies of cyclopropenium salts in fields such as electrophotocatalysis and redox flow batteries, we envisioned the possibility of devising a high-potential cyclopropenium cation catered to Ni-rich cathodes.", "question": "What's the cathode?", "answer": " Ni-rich", "answer_start": 590}
{"document_id": 75585, "context": "The electrochemical performances of bare LMO and LMO-30 min in a full cell (S-C(PAN)\u2016LMO) configuration at 1C-rate and 25 \u00b0C were compared as shown in Fig. 4a. The full cell (S-C(PAN)\u2016LMO) with the LMO-30 min cathode shows better capacity retention of 77% after 1000 cycles at 1C, corresponding to only 0.023% fading rate per cycle from the first cycle to the 1000th cycle. In contrast, the bare LMO delivers a retention capacity of 45%, about 0.055% capacity fading rate per cycle under the same conditions. The performance is noteworthy, since S. Wei et al. have reported 0.027% capacity decay rate per cycle calculated from the second to 1000th cycle, even at low current density (0.4C-rate) for the Li/S-C(PAN) cell.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75590, "context": "To study the catalytic performance of MoS2, the potentiostatic reduction of Li2S8 (10 mM based on sulfur in tetraglyme solution) was conducted on CF-based current collectors. Here, 25 \u03bcL Li2S8 was dropped onto the CF, MoS2 sheet/CF, and MoS2 ND/CF current collectors as the cathodes. CR2032 coin cells were assembled using as-prepared cathodes, Li metal anodes, Celgard separators, and 25 \u03bcL 0.5 M LiTFSI tetraglyme electrolyte. The cells were discharged to 2.06 V at 0.112 mA, to reduce all the long chain polysulfides to Li2S4. Then, the cells were kept potentiostatically at 2.05 V to drive the nucleation and growth of Li2S until the current dropped below 10\u22125 A. The current\u2013time curves were integrated based on Faraday's law to evaluate the capacities from the precipitation of Li2S on the various current collectors. To study the morphology of the precipitated Li2S, the operated cells were dissembled in a glovebox and washed with flooded DME before taking them for SEM observation.", "question": "What's the cathode?", "answer": "CR2032 coin cells", "answer_start": 284}
{"document_id": 75590, "context": "To study the catalytic performance of MoS2, the potentiostatic reduction of Li2S8 (10 mM based on sulfur in tetraglyme solution) was conducted on CF-based current collectors. Here, 25 \u03bcL Li2S8 was dropped onto the CF, MoS2 sheet/CF, and MoS2 ND/CF current collectors as the cathodes. CR2032 coin cells were assembled using as-prepared cathodes, Li metal anodes, Celgard separators, and 25 \u03bcL 0.5 M LiTFSI tetraglyme electrolyte. The cells were discharged to 2.06 V at 0.112 mA, to reduce all the long chain polysulfides to Li2S4. Then, the cells were kept potentiostatically at 2.05 V to drive the nucleation and growth of Li2S until the current dropped below 10\u22125 A. The current\u2013time curves were integrated based on Faraday's law to evaluate the capacities from the precipitation of Li2S on the various current collectors. To study the morphology of the precipitated Li2S, the operated cells were dissembled in a glovebox and washed with flooded DME before taking them for SEM observation.", "question": "What's the anode?", "answer": "Li metal", "answer_start": 345}
{"document_id": 75590, "context": "To study the catalytic performance of MoS2, the potentiostatic reduction of Li2S8 (10 mM based on sulfur in tetraglyme solution) was conducted on CF-based current collectors. Here, 25 \u03bcL Li2S8 was dropped onto the CF, MoS2 sheet/CF, and MoS2 ND/CF current collectors as the cathodes. CR2032 coin cells were assembled using as-prepared cathodes, Li metal anodes, Celgard separators, and 25 \u03bcL 0.5 M LiTFSI tetraglyme electrolyte. The cells were discharged to 2.06 V at 0.112 mA, to reduce all the long chain polysulfides to Li2S4. Then, the cells were kept potentiostatically at 2.05 V to drive the nucleation and growth of Li2S until the current dropped below 10\u22125 A. The current\u2013time curves were integrated based on Faraday's law to evaluate the capacities from the precipitation of Li2S on the various current collectors. To study the morphology of the precipitated Li2S, the operated cells were dissembled in a glovebox and washed with flooded DME before taking them for SEM observation.", "question": "What's the electrolyte?", "answer": "25 \u03bcL 0.5 M LiTFSI tetraglyme", "answer_start": 386}
{"document_id": 75595, "context": "Later, Xu et al. investigated how the electrolyte affects the performance of 1a-based cathodes. It was shown that a KFSI solution in 1,2-dimethoxyethane (DME) enables much better rate capability and cycling stability of 1,5-AQDS, owing to a stable solid electrolyte interphase (SEI) forming in this electrolyte. For the optimized electrolyte composition, Qm was 84 mA h g\u22121 at 3C (390 mA g\u22121), and 80% of the capacity was retained after 1000 cycles.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75588, "context": "Simultaneously, the predicted structural changes of O3-Nax[Ni0.5Mn0.5]O2 during Na+ extraction/insertion are presented in Fig. 5a. With extraction of 0.75 mol of Na from O3-Na1[Ni0.5Mn0.5]O2, the c-lattice parameter gradually increased from \u223c15.97 to \u223c17.40 \u00c5 because of the reinforced repulsive force between O2\u2212 anions. Then, after an additional 0.25 mol Na extraction, it decreased to \u223c15.24 \u00c5 owing to MeO2 slab gliding arising from the structural instability, which matched well with the structural change of other layered-type cathode materials for SIBs. Furthermore, as shown in Fig. 5b, we compared the c-lattice parameters of various O3-/P3-NaxCa0.01[Ni0.5Mn0.5]O2 verified through Rietveld refinement based on operando XRD results and those of O3/P3-Nax[Ni0.5Mn0.5]O2 predicted through the first-principles calculations. We confirmed that despite the occurrence of a partial two-phase reaction, the c-lattice parameter was increased in general during extraction of Na ions from O3-Na1[Ni0.5Mn0.5]O2 to P3-Na0.25[Ni0.5Mn0.5]O2. In the case of Na0[Ni0.5Mn0.5]O2, although two phases were detected in the XRD patterns of NaxCa0.01[Ni0.5Mn0.5]O2 from the operando XRD analysis, the average value of c-lattice parameters on the two phases was similar to the c-lattice parameter predicted through first-principles calculations. Moreover, this result implies that at the Na0[Ni0.5Mn0.5]O2 composition, coexistence of O3\u2032 and O3\u2032\u2032 phases is more favorable than perfect phase transition to the O3\u2032\u2032 phase, which agrees with the experimental results of previous research studies.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75593, "context": "The comprehensive electrochemical and theoretical investigations suggested that the MoS2 NDs with strong LPS absorptivity and high catalytic property would be an ideal choice for robust electrochemical performance for LSBs. Thus, we systematically performed electrochemical measurements of MoS2 ND/porous carbon/Li2S6, in comparison with porous carbon/Li2S6 and MoS2 sheet/porous carbon/Li2S6 cathodes. Fig. 6a shows the CV curves of MoS2 ND/porous carbon/Li2S6 between 1.7\u20132.8 V vs. Li+/Li at a scan rate of 0.1 mV s\u22121. Two cathodic peaks at 2.26 and 2.01 V were delivered during the first scan, which were assigned to the reduction of long-chain polysulfides to short-chain Li2S4 and further to solid Li2S. The reversible oxidation of Li2S to polysulfides and to sulfur were presented by two anodic peaks at 2.39 and 2.47 V, respectively. In the following three cycles, the overlap of the discharge/charge peaks evidently indicated the excellent reversibility of the MoS2 ND/porous carbon/Li2S6 electrode. Note that a slight negative shift of the cathodic peak from 2.26 V in the 1st sweep to 2.28 V in the following sweeps could be observed, possibly due to the increased polarization as the starting material changed from a liquid catholyte to solid sulfur from the 2nd cycle. The excellent reversibility was also confirmed by discharging/charging at 0.1C for 100 cycles (Fig. 6b). The MoS2 ND/porous carbon/Li2S6 electrode presented a capacity of 1107 mA h g\u22121 at the 2nd cycle and retained 1020 mA h g\u22121 after 100 cycles, rendering a low capacity degradation rate of 0.08% per cycle. In contrast, the porous carbon/Li2S6 and MoS2 sheet/porous carbon/Li2S6 presented much higher capacity fading rates of 0.5% and 0.19% per cycle, respectively (Fig. S11, ESI\u2020).", "question": "What's the cathode?", "answer": "carbon/Li2S6", "answer_start": 380}
{"document_id": 75597, "context": "To further probe the electrochemical performance of the UTCNF, a kinetic analysis was conducted. Fig. 4a shows the CV curves of the UTCNF at different scan rates. The redox electrochemical reactions occurring on the UTCNF may be described as the reversible reactions Ni(OH)2 + OH\u2212 \u2194 NiOOH + H2O + e\u2212 and Co(OH)2 + OH\u2212 \u2194 CoOOH + H2O + e\u2212. According to the formula i = k1v + k2v1/2 (i and v are the current and scan rate), i at a given potential can be divided into capacitive limited effects (k1v) and diffusion-controlled effects (k2v1/2). As illustrated in Fig. 4b, the detailed capacitive fraction (blue region) was calculated to be 35.8% at 0.5 mV s\u22121. Moreover, the capacitive contributions at 0.1 and 1 mV s\u22121 were also determined (Fig. 4c) to be 20.6% and 40.4%, respectively, which indicates that the electrochemical process is controlled by both capacitive behavior and diffusion. Fig. 4d shows the Nyquist plots of the UTCNF//Zn battery and the CNF//Zn battery, and the fitting values are listed in Table S3.\u2020 The UTCNF//Zn battery shows a larger charge transfer resistance Rct (4.1 \u03a9) than that of the CNF//Zn battery (2.4 \u03a9), which may be due to the decreased conductivity due to in situ formation of cobalt/nickel composite hydroxides after ultrasonic treatment. Such a markedly enhanced performance of the UTCNF//Zn battery may be attributed to the formed surface-active materials and the unique porous structure of the UTCNF cathode.", "question": "What's the cathode?", "answer": "UTCNF ", "answer_start": 1433}
{"document_id": 75591, "context": "The need to increase the energy density of Li-ion batteries leads to continual development of electrode material technology, including engineering of the physicochemical properties of cathode materials. Among them, Li-rich layered oxides are attracting considerable research attention as a candidate for high performance positive electrodes due to their high specific charge (capacity), exceeding 200 mA h g\u22121. This group of compounds, proposed firstly by Thackeray and Johnson, include pristine Li2MnO3 or Li2MnO3 with partial substitution of Mn with other transition metals (TMs) and is often described as: xLi2MnO3\u00b7(1 \u2212 x)LiMO2 (or alternatively Li[LiyMn1\u2212y\u2212zMz]O2) (M \u2013 transition metal). Although, initially Thackeray et al. reported that Li2MnO3 (theoretical capacity 468 mA h g\u22121) is electrochemically inactive because Mn4+ cannot be oxidized to higher states, further studies showed that by means of appropriate activation processes Li2MnO3 can deliver higher discharge capacities than LiMnO2. Further studies by Kobobuchi et al. suggested that upon delithiation the local electronic state of lattice oxygen in Li2MnO3 may change, affecting the material performance. XAS studies of the O K-edge and Mn L-edge showed that in the Li-rich NMC sample charged up to 4.7 V vs. Li+/Li, oxygen ions also contribute to the reduction of manganese via electron transition from O-1s to the hybridized bands composed of O-2p and Mn-3dx2\u2212y2. As a result, the change of the local electronic state surrounding Mn4+ ions triggers their migration within TMs and/or into the Li layers, which may be reflected in phase transformation of the initial monoclinic (C2/m) layered structure into either a rhombohedral (Rm) and/or a spinel structure. As confirmed by Amalraj et al. phase transition of Li2MnO3 from layered to spinel-like structures occurs even at potentials as low as 4.3 V, while at 4.5 V Li2MnO3 by partial loss of Li2O forms Li2\u2212xMnO3\u2212x/2 with enhanced stability associated with the existence of a composite structure built up with Li2MnO3 domains in a LiMnO2 matrix.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75596, "context": "C-based materials such as spheres, fibers, and cages have been reported to adsorb polysulfides. Their ability to trap LiPSs in cathodes suppresses the shuttle effect, and improves the cycling of Li\u2013S batteries. To compare the LiPS adsorption on hollow Co5.47Nx\u2013C and C spheres, visual adsorption tests were conducted using Li2S6 as the LiPS; the results are presented in Fig. 4a. The initially yellow Li2S6 solution containing hollow Co5.47Nx\u2013C spheres became colorless after 8 h. In contrast, the equivalent test with C spheres showed slight fading of the yellow solution. This showed that the Co5.47Nx\u2013C spheres adsorbed the LiPS more readily than the C spheres. This was attributed to both physical and chemical adsorption because of the Co5.47Nx nanoparticles and mesoporous hollow layer of the Co5.47Nx\u2013C spheres.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75608, "context": "Fig. 5b and d display the images of S-C(PAN) anodes cycled with bare LMO and LMO-30 min, respectively. Also, the images of S-C(PAN) anodes cycled with PLMO-10 min and LMO-10 min are shown in Fig. S4b and d.\u2020 The morphologies of cycled S-C(PAN) electrodes with bare LMO, PLMO-10 min, and LMO-10 min electrodes seem rough with obvious cracks. In contrast, Fig. 5d displays the smooth surface of the S-C(PAN) electrode with no severe cracking. The surface feature and integrity are believed to be related to the manganese dissolution of the LMO cathode and the re-deposition on the anode surface, which will be discussed in detail in the following text.", "question": "What's the cathode?", "answer": "LMO", "answer_start": 538}
{"document_id": 75608, "context": "Fig. 5b and d display the images of S-C(PAN) anodes cycled with bare LMO and LMO-30 min, respectively. Also, the images of S-C(PAN) anodes cycled with PLMO-10 min and LMO-10 min are shown in Fig. S4b and d.\u2020 The morphologies of cycled S-C(PAN) electrodes with bare LMO, PLMO-10 min, and LMO-10 min electrodes seem rough with obvious cracks. In contrast, Fig. 5d displays the smooth surface of the S-C(PAN) electrode with no severe cracking. The surface feature and integrity are believed to be related to the manganese dissolution of the LMO cathode and the re-deposition on the anode surface, which will be discussed in detail in the following text.", "question": "What's the anode?", "answer": "S-C(PAN)", "answer_start": 36}
{"document_id": 75608, "context": "Fig. 5b and d display the images of S-C(PAN) anodes cycled with bare LMO and LMO-30 min, respectively. Also, the images of S-C(PAN) anodes cycled with PLMO-10 min and LMO-10 min are shown in Fig. S4b and d.\u2020 The morphologies of cycled S-C(PAN) electrodes with bare LMO, PLMO-10 min, and LMO-10 min electrodes seem rough with obvious cracks. In contrast, Fig. 5d displays the smooth surface of the S-C(PAN) electrode with no severe cracking. The surface feature and integrity are believed to be related to the manganese dissolution of the LMO cathode and the re-deposition on the anode surface, which will be discussed in detail in the following text.", "question": "What's the anode?", "answer": "S-C(PAN)", "answer_start": 123}
{"document_id": 75794, "context": "Here, we demonstrate a new method to modify the surface of an LMO electrode for the first time. A stabilized LMO cathode was achieved by the electrospun coating of PVDF and gallium (Ga) and niobium (Nb) co-doped LLZO (Li5.6Ga0.26La2.9Zr1.87Nb0.05O12, LGLZNO). The PVDF@LGLZNO fibrous film coating acts as an effective artificial CEI to suppress the manganese dissolution and significantly minimize the undesirable interfacial reaction between the cathode and electrolyte. The improved LMO was further verified by coupling with an S-C(PAN) composite anode to realize stable rate performance and long cycling stability.", "question": "What's the cathode?", "answer": "LMO ", "answer_start": 109}
{"document_id": 75794, "context": "Here, we demonstrate a new method to modify the surface of an LMO electrode for the first time. A stabilized LMO cathode was achieved by the electrospun coating of PVDF and gallium (Ga) and niobium (Nb) co-doped LLZO (Li5.6Ga0.26La2.9Zr1.87Nb0.05O12, LGLZNO). The PVDF@LGLZNO fibrous film coating acts as an effective artificial CEI to suppress the manganese dissolution and significantly minimize the undesirable interfacial reaction between the cathode and electrolyte. The improved LMO was further verified by coupling with an S-C(PAN) composite anode to realize stable rate performance and long cycling stability.", "question": "What's the anode?", "answer": "S-C(PAN) composite", "answer_start": 530}
{"document_id": 75794, "context": "Here, we demonstrate a new method to modify the surface of an LMO electrode for the first time. A stabilized LMO cathode was achieved by the electrospun coating of PVDF and gallium (Ga) and niobium (Nb) co-doped LLZO (Li5.6Ga0.26La2.9Zr1.87Nb0.05O12, LGLZNO). The PVDF@LGLZNO fibrous film coating acts as an effective artificial CEI to suppress the manganese dissolution and significantly minimize the undesirable interfacial reaction between the cathode and electrolyte. The improved LMO was further verified by coupling with an S-C(PAN) composite anode to realize stable rate performance and long cycling stability.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75603, "context": "Increasing the areal sulfur loading and decreasing the amount of electrolyte in cathodes are natural methods to meet the above requirements. However, thick sulfur electrodes suffer cracking and peeling off problems during slurry casting, thus damaging the electrode integrity. Another obstacle for thick electrodes is the poor immersion of the electrolyte, which restrains the effective sulfur utilization. A promising alternate approach is to use a polysulfide solution, designated as a catholyte, as the starting material. The liquid catholyte is ready to immerse and envelope the surface of the conductive host, thus facilitating rapid charge transfer at the electrode/electrolyte interface, and giving rise to fast reaction kinetics. In addition, highly concentrated catholytes possess an intrinsically low E/S ratio. For example, the E/S ratio of 1.5 M Li2S6 catholyte is only 3.5 \u03bcL mg\u22121, which is difficult to achieve in sulfur particle electrodes. However, the flooded amounts of LPSs in carbon/catholyte electrodes induce a severe shuttling effect due to the poor interaction between the nonpolar carbon host and polar LPSs, leading to a short cycle life. Thus, introducing polar electrocatalysts in carbon/catholyte becomes imperative.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75603, "context": "Increasing the areal sulfur loading and decreasing the amount of electrolyte in cathodes are natural methods to meet the above requirements. However, thick sulfur electrodes suffer cracking and peeling off problems during slurry casting, thus damaging the electrode integrity. Another obstacle for thick electrodes is the poor immersion of the electrolyte, which restrains the effective sulfur utilization. A promising alternate approach is to use a polysulfide solution, designated as a catholyte, as the starting material. The liquid catholyte is ready to immerse and envelope the surface of the conductive host, thus facilitating rapid charge transfer at the electrode/electrolyte interface, and giving rise to fast reaction kinetics. In addition, highly concentrated catholytes possess an intrinsically low E/S ratio. For example, the E/S ratio of 1.5 M Li2S6 catholyte is only 3.5 \u03bcL mg\u22121, which is difficult to achieve in sulfur particle electrodes. However, the flooded amounts of LPSs in carbon/catholyte electrodes induce a severe shuttling effect due to the poor interaction between the nonpolar carbon host and polar LPSs, leading to a short cycle life. Thus, introducing polar electrocatalysts in carbon/catholyte becomes imperative.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75677, "context": "Fig. 3(a) and (d) show the results of ion conductivity through EIS measurements of the porous NASICON pellets and epoxy-NASICON pellets, respectively. The NASICON ceramics sintered at 1100 \u00b0C had an ionic conductivity of 1.76 \u00d7 10\u22124 S cm\u22121. A cross-sectional SEM image of the NASICON pellet sintered at 1100 \u00b0C is shown in Fig. 3(b). Here, the solid electrolyte secures the ion transfer channel after sintering, leaving pores to remain inside. When the epoxy polymer is added to the sample, the polymer material sufficiently fills the internal pores (Fig. 3(e)). In the SEM image, it was confirmed that the empty space between the NASICON crystals was filled with a black material, which was identified as a polymer material containing C through the EDS analysis shown in Fig. 3(c) and (f). The detailed EDS analysis results for each component can be seen in ESI Fig. S4.\u2020 Comparing the components of Na, Si, Zr, and P, which are all contained in NASICON, with the components of C, which are only contained in the epoxy polymers, we can see that the epoxy polymer is completely contained in the inner pores. In the same sample, Na-ions only move through the connected ceramics, which means that adding epoxy polymers does not affect the ion conduction. The ionic conductivity after epoxy treatment of the NASICON pellet is determined to be 1.45 \u00d7 10\u22124 S cm\u22121. Therefore, epoxy polymer is not involved in the ion transport mechanism, so it can increase the physical strength while maintaining the existing ion conductivity.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75682, "context": "Since the capacitance in redox supercapacitors is mainly produced by the fast faradaic reaction occurring near a solid electrode surface at an appropriate potential, a relatively short diffusion path can be provided by nanostructured materials to improve the power density of supercapacitors. Therefore, electrode materials composed of NCPs have recently received consideration for supercapacitors. In addition, porous nanostructures increase the contact area between electrolyte and active materials. These two features lead to fast reaction kinetics. Electrode materials in supercapacitors essentially involve processes at the interface between an electrode and an electrolyte solution. Increasing the area of the interface is expected to increase the rate of the process. Porous electrode materials with high surface area per unit volume, especially with structural elements on the nanometer scale, have received considerable attention. Thus, active electrodes with meso- or nanoporous structures and good conductivity are highly desirable for high power densities.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75687, "context": "Electrolyte additives may modify lithium deposition in several different ways, e.g. by influencing initial SEI formation on the current collector, the nucleation stage of lithium metal deposition, the growth of lithium metal deposits, or some combination thereof. To investigate during which step of lithium metal electrodeposition HF plays an active role, a cell was first galvanostatically brought down to 0 V vs. the counter electrode (CE, Li/Li+) at 0.5 mA cm\u22122 in LP30 containing 100 ppm added HF to form the initial SEI on copper (Fig. 3a). The electrolyte was then removed, the cell rinsed with as-received LP30, and refilled with as-received LP30 for deposition of lithium metal (Fig. 3b). There is no voltage plateau \u223c2 V indicative of HF reduction, but we observe an additional small amount of capacity below 1 V which is consistent with solvent reduction. Lithium metal with a highly monodispersed columnar morphology (Fig. 3c) was still deposited although there was no HF in the electrolyte during electroplating. This demonstrates that it is the initial SEI on copper which directs the microstructure and that HF does not play an active role beyond the initial SEI formation. This experimental evidence is in agreement with studies in the literature that report the formation of a columnar microstructure without additives when a LiF rich layer was deposited ex situ on copper prior to cell assembly.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75473, "context": "The fabrication of the nanomesh-based cathodes is performed in several steps, starting from the formation of the AAO template, growth of the nanomesh, deposition of the active material precursor and finally its activation by reaction with a lithium source (Fig. 1). In our approach, we focused on lithiated manganese oxides (here, generally abbreviated as LMO) as the active cathode material since they can be synthesized at relatively low temperatures and their precursor (MnO2) can be easily conformally electrodeposited onto high aspect ratio structures. This made LMO the natural choice for demonstrating the potential of nanomesh-based electrodes for Li-ion batteries. It is worth noting that LMO also show a relatively high reduction potential vs. Li+/Li (for example, \u223c2.9 V for the layered LiMnO2 and 4\u20133 V for spinel LiMn2O4 ( ), are cheap and not toxic, but suffer from limited stability when cycled in liquid electrolytes.", "question": "What's the cathode?", "answer": " lithiated manganese oxides", "answer_start": 296}
{"document_id": 75473, "context": "The fabrication of the nanomesh-based cathodes is performed in several steps, starting from the formation of the AAO template, growth of the nanomesh, deposition of the active material precursor and finally its activation by reaction with a lithium source (Fig. 1). In our approach, we focused on lithiated manganese oxides (here, generally abbreviated as LMO) as the active cathode material since they can be synthesized at relatively low temperatures and their precursor (MnO2) can be easily conformally electrodeposited onto high aspect ratio structures. This made LMO the natural choice for demonstrating the potential of nanomesh-based electrodes for Li-ion batteries. It is worth noting that LMO also show a relatively high reduction potential vs. Li+/Li (for example, \u223c2.9 V for the layered LiMnO2 and 4\u20133 V for spinel LiMn2O4 ( ), are cheap and not toxic, but suffer from limited stability when cycled in liquid electrolytes.", "question": "What's the cathode?", "answer": "LMO", "answer_start": 356}
{"document_id": 75483, "context": "Acoustic wave velocity is determined by the speed of wave propagation through a medium with defined thickness. While the wave arrival time can be determined from the measured acoustic signal, thickness must be measured independently to verify the wave velocity. The expansion and contraction of a pouch cell during cycling can be imaged with transmission X-ray microscopy (TXM), which has sufficient range and pixel resolution to measure both the total cell thickness and the average layer thicknesses. TXM parameters were optimized with exposure time of 20 seconds, beam voltage of 140 kV, a 0.4\u00d7 objective lens and 90\u00b0 projection angle (Table 1). Fig. 1 illustrates the experimental configuration and example radiographs of the mechanical expansion of a pouch cell upon cycling. The commercial pouch cell chosen (LiCoO2/graphite, 210 mA h nominal capacity) has a total thickness of approximately 5.6 mm when fully charged. The measured thickness varies between 5.4 and 5.6 mm (\u223c4% change) at a rate of 1C. There is less variation (\u223c0.5%) at a rate of 3C because of less attainable capacity before hitting the 4.5 V voltage cutoff on charge. The thickness changes are dominated by the \u223c10% volume expansion and contraction of graphite anodes upon lithiation/delithiation. With 15 double-sided anodes and cathodes, each of the 30 cell layers (one layer is defined as an anode, a cathode, with a separator layer in between each electrode) is approximately 170 \u03bcm in thickness as measured by average peak-to-peak spacing (additional information on pixel thresholds for thickness measurements can be found in Fig. S1\u2013S5\u2020).", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75493, "context": "Then, Na metal was placed on the surface of the UV curing polymer electrolyte, and the product of a cell test in which a Na metal/solid electrolyte/cathode was made was placed in a 2032-coin cell. All steps were processed in a glovebox with less than 10 ppm for both oxygen and moisture. When manufacturing the bipolar stacked cell, a coin cell was prepared by putting Al foil between the two solid electrolyte cells.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75799, "context": "In order to evaluate the electrochemical performance of the obtained electrodes, two-electrode Zn\u2013MnO2 batteries were assembled using COG@MnO2 as the cathode and COG@Zn as the anode in an aqueous electrolyte containing 2 M ZnSO4 and 0.1 M MnSO4. The typical cyclic voltammetry (CV) curves of the aqueous COG@MnO2//COG@Zn battery at different scan rates are shown in Fig. 3d. There are two reduction peaks at around 1.2 and 1.4 V, which should be ascribed to the zinc insertion into MnO2 and the subsequent reduction of Mn(IV) to the Mn(III)/Mn(II) states. Similarly, the oxidation peak and shoulder appear at 1.6\u20131.8 V, corresponding to Zn-extraction from the MnO2 cathode as the Mn(III)/Mn(II) states undergo oxidation to the Mn(IV) state. The overall reaction of the battery can be formulated as follows:", "question": "What's the cathode?", "answer": "COG@MnO2", "answer_start": 134}
{"document_id": 75799, "context": "In order to evaluate the electrochemical performance of the obtained electrodes, two-electrode Zn\u2013MnO2 batteries were assembled using COG@MnO2 as the cathode and COG@Zn as the anode in an aqueous electrolyte containing 2 M ZnSO4 and 0.1 M MnSO4. The typical cyclic voltammetry (CV) curves of the aqueous COG@MnO2//COG@Zn battery at different scan rates are shown in Fig. 3d. There are two reduction peaks at around 1.2 and 1.4 V, which should be ascribed to the zinc insertion into MnO2 and the subsequent reduction of Mn(IV) to the Mn(III)/Mn(II) states. Similarly, the oxidation peak and shoulder appear at 1.6\u20131.8 V, corresponding to Zn-extraction from the MnO2 cathode as the Mn(III)/Mn(II) states undergo oxidation to the Mn(IV) state. The overall reaction of the battery can be formulated as follows:", "question": "What's the anode?", "answer": "COG@Zn", "answer_start": 162}
{"document_id": 75799, "context": "In order to evaluate the electrochemical performance of the obtained electrodes, two-electrode Zn\u2013MnO2 batteries were assembled using COG@MnO2 as the cathode and COG@Zn as the anode in an aqueous electrolyte containing 2 M ZnSO4 and 0.1 M MnSO4. The typical cyclic voltammetry (CV) curves of the aqueous COG@MnO2//COG@Zn battery at different scan rates are shown in Fig. 3d. There are two reduction peaks at around 1.2 and 1.4 V, which should be ascribed to the zinc insertion into MnO2 and the subsequent reduction of Mn(IV) to the Mn(III)/Mn(II) states. Similarly, the oxidation peak and shoulder appear at 1.6\u20131.8 V, corresponding to Zn-extraction from the MnO2 cathode as the Mn(III)/Mn(II) states undergo oxidation to the Mn(IV) state. The overall reaction of the battery can be formulated as follows:", "question": "What's the electrolyte?", "answer": "2 M ZnSO4 and 0.1 M MnSO4", "answer_start": 219}
{"document_id": 75604, "context": "The UTCNF//Zn and CNF//Zn batteries were assembled using UTCNF or CNF cathodes (an area of 1 \u00d7 1 cm2 and a thickness of 0.15 cm) and a Zn plate anode with 6 M KOH + 0.5 M Zn(Ac)2 as the electrolyte. The total mass of the UTCNF electrode was \u223c32.3 mg and the corresponding hydroxide formation rate was \u223c18.6%. Galvanostatic charge\u2013discharge (GCD) experiments were performed using a multichannel battery testing system (Land CT 2001A). Cyclic voltammetry (CV) curves and electrochemical impedance spectra (EIS) were collected on an electrochemical workstation (PARSTAT MC).", "question": "What's the cathode?", "answer": "CNF", "answer_start": 66}
{"document_id": 75606, "context": "In summary, active catholyte has been applied to assemble a high-performance hybrid supercapacitor, which relies on the reversible conversion between soluble Mn2+ and solid MnO2 at the cathode and the redox of Ti\u2013O with the bonding/de-bonding of H3O+ at the 400-KOH-Ti3C2 anode. The well-separated potential window between the cathode and anode leads to a hybrid supercapacitor with a wide voltage window of 1.7 V. This hybrid supercapacitor achieves a high energy density of 43.4 W h kg\u22121, without using any ion-selective membrane, and super-long cycle life (75% retention after 20000 cycles). Furthermore, the hybrid supercapacitor can operate well even with the frozen electrolyte at \u221270 \u00b0C. These inspiring results provide a new strategy to design high-performance hybrid supercapacitors for low temperature applications.", "question": "What's the cathode?", "answer": "MnO2 ", "answer_start": 173}
{"document_id": 75804, "context": "In summary, MoP was synthesized on nickel foam, on which NiCo-LDH was electrodeposited to form catalyst electrodes (MoP@NiCo-LDH/NF-x), where x represents the electrodeposition time period, and they were explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea\u2013water or water electrolysis. The morphology and catalytic performance were investigated using a series of physical characterization and electrochemical tests. The results show that at an electrolysis current density of 100 mA cm\u22122, the anode potential of the MoP@NiCo-LDH/NF-20 electrode is 1.392 V (vs. RHE) for UOR, 233 mV less than that of an IrO2/NF electrode (1.625 V); and the cathode potential of the MoP@NiCo-LDH/NF-20 electrode is 0.255 V (vs. RHE) for HER, closest to that of IrO2/NF (170 mV). For the two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20), the cell voltage is as low as 1.405 V for urea\u2013water electrolysis and 1.697 V for water electrolysis at a current density of 100 mA cm\u22122, even lower than those of a Pt/C/NF\u2016IrO2/NF cell. Moreover, after 20 hours of continuous electrolysis, the performance and morphology of the catalyst are almost unchanged, indicating that it has both high activity and stability. The results show that the developed MoP@NiCo-LDH/NF-20 is a promising bifunctional catalyst.", "question": "What's the cathode?", "answer": "MoP@NiCo-LDH/NF-20", "answer_start": 808}
{"document_id": 75804, "context": "In summary, MoP was synthesized on nickel foam, on which NiCo-LDH was electrodeposited to form catalyst electrodes (MoP@NiCo-LDH/NF-x), where x represents the electrodeposition time period, and they were explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea\u2013water or water electrolysis. The morphology and catalytic performance were investigated using a series of physical characterization and electrochemical tests. The results show that at an electrolysis current density of 100 mA cm\u22122, the anode potential of the MoP@NiCo-LDH/NF-20 electrode is 1.392 V (vs. RHE) for UOR, 233 mV less than that of an IrO2/NF electrode (1.625 V); and the cathode potential of the MoP@NiCo-LDH/NF-20 electrode is 0.255 V (vs. RHE) for HER, closest to that of IrO2/NF (170 mV). For the two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20), the cell voltage is as low as 1.405 V for urea\u2013water electrolysis and 1.697 V for water electrolysis at a current density of 100 mA cm\u22122, even lower than those of a Pt/C/NF\u2016IrO2/NF cell. Moreover, after 20 hours of continuous electrolysis, the performance and morphology of the catalyst are almost unchanged, indicating that it has both high activity and stability. The results show that the developed MoP@NiCo-LDH/NF-20 is a promising bifunctional catalyst.", "question": "What's the anode?", "answer": "MoP@NiCo-LDH/NF-20 electrode ", "answer_start": 659}
{"document_id": 75804, "context": "In summary, MoP was synthesized on nickel foam, on which NiCo-LDH was electrodeposited to form catalyst electrodes (MoP@NiCo-LDH/NF-x), where x represents the electrodeposition time period, and they were explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea\u2013water or water electrolysis. The morphology and catalytic performance were investigated using a series of physical characterization and electrochemical tests. The results show that at an electrolysis current density of 100 mA cm\u22122, the anode potential of the MoP@NiCo-LDH/NF-20 electrode is 1.392 V (vs. RHE) for UOR, 233 mV less than that of an IrO2/NF electrode (1.625 V); and the cathode potential of the MoP@NiCo-LDH/NF-20 electrode is 0.255 V (vs. RHE) for HER, closest to that of IrO2/NF (170 mV). For the two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20), the cell voltage is as low as 1.405 V for urea\u2013water electrolysis and 1.697 V for water electrolysis at a current density of 100 mA cm\u22122, even lower than those of a Pt/C/NF\u2016IrO2/NF cell. Moreover, after 20 hours of continuous electrolysis, the performance and morphology of the catalyst are almost unchanged, indicating that it has both high activity and stability. The results show that the developed MoP@NiCo-LDH/NF-20 is a promising bifunctional catalyst.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75811, "context": "Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75811, "context": "Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.", "question": "What's the anode?", "answer": "penta-graphene", "answer_start": 747}
{"document_id": 75811, "context": "Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75624, "context": "Flexible supercapacitors are playing an increasingly important role in energy storage due to their viability in flexible intelligent wearable electronic devices, which require irregular power supply at different discharge rates. Two-dimensional (2D) nanomaterials have gradually become potential electrode materials for flexible supercapacitors due to their atomic thickness and electrochemically active surface, especially since they allow the development of binder-free flexible electrodes with improved capacitance. 2D materials can provide slit-shaped ion diffusion channels that enable fast movement of electrolyte ions into the electrode bulk.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75618, "context": "To study the electrolyte reduction processes resulting in SEI formation, cyclic voltammetry (CV) was performed systematically as a function of added HF concentration (as-received, +10, +100, and +500 ppm) and voltage sweep rate. Fig. 5 shows a series of CV scans measured at 5 mV s\u22121 in electrolytes with varying concentrations of HF. The peak at \u223c2 V, indicated by the dashed line, results from the electrocatalytic reduction of HF to form LiF (reaction (2)). The additional peak at higher potential in the as-received electrolyte may be attributed to either PF6\u2212 or POF3 reduction. The slight shift in peak position to higher potentials (from 1.9 to 2 V) with increasing HF concentration is consistent with the report by Strmcnik et al. Solutions with more HF exhibit higher peak currents and increased capacity going into SEI formation. If a uniform film of LiF alone were fully passivating the copper surface, this would be achieved at a specific capacity as further HF reduction would be prevented by the passivation, and increased HF in the electrolyte would not lead to increased SEI capacity. However, this data suggests that LiF alone does not passivate the copper surface at these HF concentrations and scan rates because increased HF concentration in the electrolyte results in a corresponding increase in the capacity of the HF reduction peak. Passivating LiF films can be formed under different conditions, however, namely at slower scan rates and on smoother single-crystalline substrates. We rationalize that HF reduction is limited by the availability of HF at this interface, which in turn determines the amount of LiF that is formed in the initial SEI.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75621, "context": "We report, for the first time, that DPPT-TT is a lower performance channel material compared to P3HT and PBTTT. For DPPT-TT, the ON current (\u223c\u22121.0 \u03bcA), VON value (\u223c0.63 V), and transconductance (0.012 mS), are far below the performance of P3HT and PBTTT. Still, the addition of DBSA to the electrolyte is effective in enhancing its performance and results in a significant increase in the ON current and decrease in the operation voltage. The positive effect of adding DBSA to the electrolyte extends not only to DPPT-TT but also PBTTT, where it appears to have an even stronger effect.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75622, "context": "Inspired by the remarkably active Mn4CaO5 clusters for water oxidation, Mn3O4 with high-concentration and stable Mn3+ has, therefore, been extensively researched as an efficient electrocatalyst for OER. In the spinel structure Mn2+Mn23+O4, Mn existed as Mn2+ and Mn3+; here, Mn3+ occupied the octahedral site and Mn2+ ion occupied the tetrahedral site. The coexistence of Mn2+ and Mn3+ offers excellent OER activity. Therefore, numerous studies have focused on exploring high-quality Mn3O4 catalysts for efficient electrocatalytic OER. Further, earlier studies have also demonstrated that Mn3O4 electrocatalysts are highly active toward OER in neutral and alkaline media. For example, Nam's group reported the fabrication of 4 and 8 nm Mn3O4 nanoparticles (Fig. 13a and b). Owing to the enlarged surface area and improved electrical conductivity, the as-obtained Mn3O4 nanoparticles showed apparently higher OER activity in comparison with other Mn oxides (Fig. 13c). Remarkably, the optimized 8 nm Mn3O4 nanoparticles that were loaded on the surface of NFs exhibited outstanding OER activity with overpotential of only 395 mV at 10 mA cm\u22122 under neutral conditions, which was much superior to those of Fe-, Co-, and Ni-based oxides. As demonstrated by Maruthapandian et al., Mn3O4 catalysts also showed excellent electrocatalytic performance for OER in basic solutions (Fig. 13d and e). In particular, they demonstrated the synthesis of Ni-doped Mn3O4 catalysts, which showed significantly enhanced OER electrocatalytic activity in 1 M KOH solution with overpotential of 283 mV at 10 mA cm\u22122 (Fig. 13f). Further, a mechanistic study revealed that the largely improved OER performance could be ascribed to the enhanced adsorption/desorption of hydroxide and oxygen atoms, boosting the formation of metal oxyhydroxide/hydroperoxo. Moreover, the efficient electron charge between the electrolyte and Mn3O4 and enlarged electrochemical surface active sites facilitated the promotion of electrocatalytic OER performance.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75632, "context": "Typically, the working electrodes were fabricated by mixing 10 wt% of the binder polytetrafluoroethylene (PTFE), 10 wt% conductive agent (Super-P-Li) and 80 wt% of active materials (MnO2, K0.296Mn0.926O2 and active carbon). Ethanol was used to make the above materials into a slurry and Ni foam was employed as the current collector to coat the slurry with a mass loading of around 3 mg cm\u22122. Each electrode was dried for 6 hours in the oven and finally subjected to a pressure of 10 MPa. Electrochemical tests were performed on a three-electrode system with 1 M potassium sulfate as the electrolyte with the HgO/Hg as the reference electrode and Pt foil as the counter electrode. The CHI 660E Electrochemical Workstation was used to test the galvanostatic charge\u2013discharge (GCD) and cyclic voltammetry (CV). The Zahner IM6 Electrochemical Workstation was employed to measure the electrochemical impedance spectroscopy (EIS). The LAND battery system was used to test the cycling life.", "question": "What's the electrolyte?", "answer": "1 M potassium sulfate", "answer_start": 559}
{"document_id": 75631, "context": "In summary, the mechanism of Li dendrite formation in LLZTO was discussed in terms of energy band structure as well as defect states, and was investigated by REELS, SPEM, and Nano Q-DLTS. The experimental results corroborate that the higher defect densities at the GBs lower the SBH by 0.5 eV and makes metallic Li atoms propagate along the GBs in LLZTO. As a way of preventing Li dendrite formation in LLZTO, bandgap engineering by the laser annealing treatment was proposed. Amorphous LLZTO and Li2O2 layers formed after laser annealing hinder the Li dendrite formation by blocking the electron injection. The hybrid electrolyte cell comprising the laser-treated LLZTO sample exhibits significant improvement in cycling performance and stability. Consequently, the laser annealing treatment on the LLZTO electrolytes can direct the development of materials engineering toward high-performance solid-state batteries. Furthermore, the analytical approach in this study highlights the importance of the electronic band structure of LLZTO for its stability and provides the direction to study various solid electrolyte materials.", "question": "What's the electrolyte?", "answer": "LLZTO ", "answer_start": 800}
{"document_id": 75635, "context": "Anthraquinone-1,5-disulfonic acid disodium salt (1,5-AQDS, 1a) was first proposed for potassium batteries by Xu et al. In a carbonate-based electrolyte, the authors achieved the reversible capacity per material mass (Qm) of 95 mA h g\u22121 at 0.1C (13 mA g\u22121), and after a hundred cycles the capacity was 78 mA h g\u22121.", "question": "What's the electrolyte?", "answer": "carbonate-based", "answer_start": 124}
{"document_id": 75637, "context": "The high-rate performance of 3Mg/Mg2Sn was mainly attributed to a low RCT. EIS spectra revealed that the RCT in 3Mg/Mg2Sn is significantly smaller than that in Mg2Sn (Fig. S5\u2020). While the RCT values in 3Mg/Mg2Sn varied between 77 and 140 \u03a9, those in Mg2Sn varied in the range of 500\u20132500 \u03a9. This was not surprising because the apparent RCT is dependent on the surface area that is accessible by electrolytes. The larger BET surface area and micro-to-macroporosity of 3Mg/Mg2Sn, therefore, resulted in a significantly low RCT, which eventually contributed to the high-rate performance.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75642, "context": "For electrochromic applications, the device shows rapid, self-powered color switching and multicolor display (color switching from light yellow to transparent, light red, dark green, dark blue and black, corresponding to the combination of the different states of the two films). As an energy storage device, the as-assembled device provides three different open-circuit potentials with an overall areal capacity of up to 933 mA h m\u22122. Meanwhile, the utilization of the mixed Al/Li-ion electrolyte and the addition of PEDOT:PSS into the inorganic materials greatly promote the cycle stability of the cathode films. Such a new design of the EES device with multicolor display, large charge capacity and high cycle stability can be promising for future color switching/energy storage applications, which may also provide new insights into the design of multifunctional devices.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75642, "context": "For electrochromic applications, the device shows rapid, self-powered color switching and multicolor display (color switching from light yellow to transparent, light red, dark green, dark blue and black, corresponding to the combination of the different states of the two films). As an energy storage device, the as-assembled device provides three different open-circuit potentials with an overall areal capacity of up to 933 mA h m\u22122. Meanwhile, the utilization of the mixed Al/Li-ion electrolyte and the addition of PEDOT:PSS into the inorganic materials greatly promote the cycle stability of the cathode films. Such a new design of the EES device with multicolor display, large charge capacity and high cycle stability can be promising for future color switching/energy storage applications, which may also provide new insights into the design of multifunctional devices.", "question": "What's the electrolyte?", "answer": "mixed Al/Li-ion", "answer_start": 470}
{"document_id": 75638, "context": "Polylactic acid (PLA) is a type of bio-based, renewable, and biodegradable material made by starch raw materials from renewable plant resources. The physical properties of small molecules of poly(ethylene glycol) (PEG)\u2013PLA were analyzed with FAMD simulations with the COMPASS forcefield, and the mechanical properties of large-chain PLC were studied using CGMD with the MARTINI force field. Recent research focused on designing PLA composites through MD simulations to improve the inherently weak mechanical properties of PLA. For example, MD simulations of the microstructures of PLA\u2013o-carboxymethyl chitosan (CMC) composites showed that introducing CMC enhanced the stiffness of PLA, and the analysis of the interfacial properties of PLA\u2013graphene composites yielded a scheme to design nanocomposites with high strength and toughness. Other than characterizing the molecular phenomena of polymers, the swelling behavior of cross-linked hydrogels in poor solvents were also studied using a CG model, where counterions were considered explicitly. Similar swelling conformations were found for charged cross-linked hydrogels as single polyelectrolyte chains. Furthermore, the effects of various experimentally-controlled parameters were systematically investigated to provide insight into the rational design of hydrogels with desired conformations and properties.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75645, "context": "Currently, metal or metal compounds have been widely investigated as electrode materials for SCs owing to their high theoretical specific capacity. Nevertheless, the inferior electronic conductivity, poor ion-diffusion and instability (metal) of such materials still hinder their practical applications. Massive research studies have indicated that coupling with a high electronic conductivity carbon matrix is a fascinating method to address the above problems. Electrospun 1D CNFs possess high mechanical strength, excellent electronic conductivity, and a high surface area, making them a promising substrate/host for metal or metal compounds. Furthermore, CNFs within CNF-based composites offer a number of advantages: (i) the ability to effectively inhibit the agglomeration of active materials, (ii) substantial enhancement of the electrochemically active surface area, (iii) the ability to maintain the integrity of the composite electrode, (iv) more effective electrolyte permeation and ion/electron transport and (v) an enlarged voltage window. As show in Table 2, the metal compounds showed enhanced cycling performance and rate capability when hybridized with highly compatible CNFs as electrode materials in SCs. Herein, based on diverse extensively studied active materials (i.e. metals, metal oxides, metal sulfides, metal nitrides, metal phosphides, metal carbides, other nanocarbons, metal hydroxides, MOFs, and conducting polymers), different types of CNF-based composites are divided and discussed.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75649, "context": "A pre-lithiated MCMB anode (Fig. S9\u2020) is utilized to match the LLOs cathode for assembling full cells. Since the matched capacity ratio of the anode/cathode is about 1.1 in the full cells, the specific capacity is evaluated based on the weight of the LLO cathode, while the energy density is calculated based on all the components of the full cell. The electrochemical performance of MCMB|LLO full cells is shown in Fig. 5. The full cells show specific capacities of 270 and 256 mA h g\u22121 at the cut-offs of 4.7 V and 4.5 V with initial coulombic efficiencies of 81.2% and 84.5%, respectively. As exhibited in Fig. 5(b\u2013f), the full cells exhibit a rapid decay of discharge capacity with a capacity retention of only 61.2% after 100 cycles at 0.5C at the cut-off of 4.7 V. By contrast, the full cells show a much enhanced cycling stability with a capacity retention of 84.5% at the cut-off of 4.4 V after the same cycling period. Also, the full cells cycled at 4.4 V show low electrochemical polarization (Fig. S10\u2020), corresponding to the stable discharge voltage as shown in Fig. 5(f). All the components of a typical pouch full cell are shown in Fig. S11,\u2020 and the mass fraction of the cathode in a LIB full cell reaches \u223c35%. High energy densities of \u223c320 and 305 W h kg\u22121 are achieved for the MCMB|LLO full cells at the cut-offs of 4.7 and 4.4 V, respectively. If a high-capacity Si/C anode is utilized, the energy density of the full cells can be further enhanced. Improved cycling stability of energy density is also confirmed for the full cells cycled at the cut-off of 4.4 V (Fig. 5(f)). The rate capabilities of the MCMB|LLO full cells at the cut-offs of 4.7 V and 4.4 V are illustrated in Fig. 5(d and e) and S12.\u2020 The full cells cycled at the cut-off of 4.4 V deliver reversible capacities of 204.6, 186.1, 152.0, and 125.2 mA h g\u22121 at the high rates of 1C, 2C, 5C and 10C, respectively, which are much higher than those of cells cycled at the cut-off of 4.7 V. Similar to half cells, the full cells exhibit improved electrochemical performance at the low cut-off of 4.4 V. The performance of MCMB|LLO full cells can be further improved by optimizing the electrolyte, capacity ratio of the anode/cathode, prelithiation and full cell design in future studies.", "question": "What's the cathode?", "answer": "LLOs", "answer_start": 63}
{"document_id": 75649, "context": "A pre-lithiated MCMB anode (Fig. S9\u2020) is utilized to match the LLOs cathode for assembling full cells. Since the matched capacity ratio of the anode/cathode is about 1.1 in the full cells, the specific capacity is evaluated based on the weight of the LLO cathode, while the energy density is calculated based on all the components of the full cell. The electrochemical performance of MCMB|LLO full cells is shown in Fig. 5. The full cells show specific capacities of 270 and 256 mA h g\u22121 at the cut-offs of 4.7 V and 4.5 V with initial coulombic efficiencies of 81.2% and 84.5%, respectively. As exhibited in Fig. 5(b\u2013f), the full cells exhibit a rapid decay of discharge capacity with a capacity retention of only 61.2% after 100 cycles at 0.5C at the cut-off of 4.7 V. By contrast, the full cells show a much enhanced cycling stability with a capacity retention of 84.5% at the cut-off of 4.4 V after the same cycling period. Also, the full cells cycled at 4.4 V show low electrochemical polarization (Fig. S10\u2020), corresponding to the stable discharge voltage as shown in Fig. 5(f). All the components of a typical pouch full cell are shown in Fig. S11,\u2020 and the mass fraction of the cathode in a LIB full cell reaches \u223c35%. High energy densities of \u223c320 and 305 W h kg\u22121 are achieved for the MCMB|LLO full cells at the cut-offs of 4.7 and 4.4 V, respectively. If a high-capacity Si/C anode is utilized, the energy density of the full cells can be further enhanced. Improved cycling stability of energy density is also confirmed for the full cells cycled at the cut-off of 4.4 V (Fig. 5(f)). The rate capabilities of the MCMB|LLO full cells at the cut-offs of 4.7 V and 4.4 V are illustrated in Fig. 5(d and e) and S12.\u2020 The full cells cycled at the cut-off of 4.4 V deliver reversible capacities of 204.6, 186.1, 152.0, and 125.2 mA h g\u22121 at the high rates of 1C, 2C, 5C and 10C, respectively, which are much higher than those of cells cycled at the cut-off of 4.7 V. Similar to half cells, the full cells exhibit improved electrochemical performance at the low cut-off of 4.4 V. The performance of MCMB|LLO full cells can be further improved by optimizing the electrolyte, capacity ratio of the anode/cathode, prelithiation and full cell design in future studies.", "question": "What's the anode?", "answer": "MCMB", "answer_start": 16}
{"document_id": 75649, "context": "A pre-lithiated MCMB anode (Fig. S9\u2020) is utilized to match the LLOs cathode for assembling full cells. Since the matched capacity ratio of the anode/cathode is about 1.1 in the full cells, the specific capacity is evaluated based on the weight of the LLO cathode, while the energy density is calculated based on all the components of the full cell. The electrochemical performance of MCMB|LLO full cells is shown in Fig. 5. The full cells show specific capacities of 270 and 256 mA h g\u22121 at the cut-offs of 4.7 V and 4.5 V with initial coulombic efficiencies of 81.2% and 84.5%, respectively. As exhibited in Fig. 5(b\u2013f), the full cells exhibit a rapid decay of discharge capacity with a capacity retention of only 61.2% after 100 cycles at 0.5C at the cut-off of 4.7 V. By contrast, the full cells show a much enhanced cycling stability with a capacity retention of 84.5% at the cut-off of 4.4 V after the same cycling period. Also, the full cells cycled at 4.4 V show low electrochemical polarization (Fig. S10\u2020), corresponding to the stable discharge voltage as shown in Fig. 5(f). All the components of a typical pouch full cell are shown in Fig. S11,\u2020 and the mass fraction of the cathode in a LIB full cell reaches \u223c35%. High energy densities of \u223c320 and 305 W h kg\u22121 are achieved for the MCMB|LLO full cells at the cut-offs of 4.7 and 4.4 V, respectively. If a high-capacity Si/C anode is utilized, the energy density of the full cells can be further enhanced. Improved cycling stability of energy density is also confirmed for the full cells cycled at the cut-off of 4.4 V (Fig. 5(f)). The rate capabilities of the MCMB|LLO full cells at the cut-offs of 4.7 V and 4.4 V are illustrated in Fig. 5(d and e) and S12.\u2020 The full cells cycled at the cut-off of 4.4 V deliver reversible capacities of 204.6, 186.1, 152.0, and 125.2 mA h g\u22121 at the high rates of 1C, 2C, 5C and 10C, respectively, which are much higher than those of cells cycled at the cut-off of 4.7 V. Similar to half cells, the full cells exhibit improved electrochemical performance at the low cut-off of 4.4 V. The performance of MCMB|LLO full cells can be further improved by optimizing the electrolyte, capacity ratio of the anode/cathode, prelithiation and full cell design in future studies.", "question": "What's the anode?", "answer": "Si/C", "answer_start": 1382}
{"document_id": 75639, "context": "The anchoring and catalytic effect of the MoS2 NDs could be more clearly evaluated by cycling batteries at high current densities, which requires a stronger regulation of LPS diffusion and higher redox reaction kinetics at the electrode/electrolyte interfaces. Here, the MoS2 ND/porous carbon/Li2S6 electrodes exhibited discharge capacities of 1156, 1071, 993, 955, 919, and 883 mA h g\u22121 at 0.1, 0.2, 0.5, 1, 2, and 4C, respectively (Fig. 6c). Accordingly, the capacity retention from 0.1 to 2C was determined to be 79.5% for MoS2 ND/porous carbon/Li2S6. Under the same measurement conditions, the capacity retentions for porous carbon/Li2S6 and MoS2 sheet/porous carbon/Li2S6 were only 1.2% and 22.7%, respectively (Fig. S12, ESI\u2020). Statistical analyses of the discharge/charge voltage profiles (Fig. S12, ESI\u2020) revealed that MoS2 ND/porous carbon/Li2S6 retained the largest amount of polysulfides and the highest conversion efficiency with increasing current densities among the three electrodes. It is worth noting that the highly conductive porous carbon film also contributed to the excellent performance of MoS2 ND/porous carbon/Li2S6 by offering a physical barrier and electron conductive pathway to the polysulfides.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75651, "context": "As illustrated in Fig. 2a, the TDAC possesses a 2\u03c0 electron aromatic system that can readily undergo a single electron redox reaction to generate the corresponding TDAC radical dication. Fig. 2b presents the redox potential and solubility of TDAC salt in comparison with those of the state-of-the-art high-potential shuttle molecules. Ideally, the redox potential (protection potential) should be \u223c0.2\u20130.3 V above the upper cut-off voltage of LIBs (normally at 4.3 V). A lower or higher potential outside the range would have the risk of escalated self-discharge during normal operation or an irreversible decomposition of battery components during overcharging. Additionally, a high solubility is desirable since it determines the maximum shuttling current. In these regards, TDAC outperforms all other shuttle candidates with the adequate redox potential of 4.55 V (vs. Li+/Li) and the highest solubility of 0.5 M (Fig. S2\u2020). The electrolyte viscosity before and after the TDAC addition was also investigated. The concentration of 0.2 M was found to be the optimal amount. The viscosity of 0.2 M TDAC electrolyte is 2.72 mPa compared with 2.43 mPa of baseline electrolyte. The electro-kinetics of the TDAC was next investigated by cyclic voltammetry (CV) analysis as shown in Fig. 2c. Even with a high scan rate of 200 mV s\u22121, TDAC still exhibited a pair of well-defined redox peaks, implying a fast mass transport process within the bulk electrolyte. As shown in Fig. 2d, the diffusion coefficient of TDAC is determined to be 6 \u00d7 10\u22126 cm\u22122 s\u22121, which is very comparable with that of other reported shuttles. As displayed in Fig. 2e, after 1000 CV scans, the potential gap between the anodic and cathodic peaks becomes only 60 mV wider, and there is no obvious deterioration of the peak current intensity. Such excellent electrochemical stability has rarely been reported among other 4V-class shuttles. The inset photograph in Fig. 2e presents a shiny Li surface with no bubble generation after storing in TDAC-containing electrolyte solution for six months, indicating a high chemical inertness of the TDAC toward Li metal.", "question": "What's the electrolyte?", "answer": "0.2 M TDAC", "answer_start": 1092}
{"document_id": 75651, "context": "As illustrated in Fig. 2a, the TDAC possesses a 2\u03c0 electron aromatic system that can readily undergo a single electron redox reaction to generate the corresponding TDAC radical dication. Fig. 2b presents the redox potential and solubility of TDAC salt in comparison with those of the state-of-the-art high-potential shuttle molecules. Ideally, the redox potential (protection potential) should be \u223c0.2\u20130.3 V above the upper cut-off voltage of LIBs (normally at 4.3 V). A lower or higher potential outside the range would have the risk of escalated self-discharge during normal operation or an irreversible decomposition of battery components during overcharging. Additionally, a high solubility is desirable since it determines the maximum shuttling current. In these regards, TDAC outperforms all other shuttle candidates with the adequate redox potential of 4.55 V (vs. Li+/Li) and the highest solubility of 0.5 M (Fig. S2\u2020). The electrolyte viscosity before and after the TDAC addition was also investigated. The concentration of 0.2 M was found to be the optimal amount. The viscosity of 0.2 M TDAC electrolyte is 2.72 mPa compared with 2.43 mPa of baseline electrolyte. The electro-kinetics of the TDAC was next investigated by cyclic voltammetry (CV) analysis as shown in Fig. 2c. Even with a high scan rate of 200 mV s\u22121, TDAC still exhibited a pair of well-defined redox peaks, implying a fast mass transport process within the bulk electrolyte. As shown in Fig. 2d, the diffusion coefficient of TDAC is determined to be 6 \u00d7 10\u22126 cm\u22122 s\u22121, which is very comparable with that of other reported shuttles. As displayed in Fig. 2e, after 1000 CV scans, the potential gap between the anodic and cathodic peaks becomes only 60 mV wider, and there is no obvious deterioration of the peak current intensity. Such excellent electrochemical stability has rarely been reported among other 4V-class shuttles. The inset photograph in Fig. 2e presents a shiny Li surface with no bubble generation after storing in TDAC-containing electrolyte solution for six months, indicating a high chemical inertness of the TDAC toward Li metal.", "question": "What's the electrolyte?", "answer": "TDAC-containing", "answer_start": 2008}
{"document_id": 75650, "context": "Electrochemical impedance spectroscopy (EIS) measurements were performed by Pt sputtering on both sides of the solid electrolyte pellets, and electrochemical characterization was done using SUS electrodes. Biologic VSP-300 models were electrochemically tested at a frequency range of 7 MHz to 100 MHz at 10 mV. Ionic conductivity was calculated using the following expression: where \u03c3 is the ionic conductivity (S cm\u22121), l is the thickness of the sample (cm), A is the measurement area (cm), and R is total resistance (\u03a9).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75658, "context": "Fluorination can be used as a strategy to suppress the anionic redox activity, which leads to irreversible oxygen gas formation. It has also been found that the fluorination increases accessible capacity when sufficiently high concentration of fluorine is added. In spite of high fluorine content, there have been some experimental observations which indicate the anionic redox activities of oxyfluorides such as Li2Mn2/3Nb1/3O2F, Li2Mn1/2Ti1/2O2F and Li2MnO2F when they are charged up to 4.5 V or above. In this work, we focus on Li2VO2F material as a comprehensive electrochemical study showed promising results such as good initial capacity and rate capability. However, it suffers from poor cycling performance due, in part, to degradation processes occurring at the electrode\u2013electrolyte interface during extended cycling. We report a comprehensive computational and experimental investigation on the evolution of the anionic redox process in Li2VO2F under typical cycling conditions. The computational simulations suggest that the oxygen species evolve subsequently to peroxide and to superoxide when the cell is charged up to 4.1 V, a potential lower than the commonly used upper limit of 4.5 V to 4.8 V. The formation of superoxide is confirmed using electron paramagnetic resonance spectroscopy. The superoxide remains to be present in the material upon discharge, which suggests that the superoxide formation is not entirely reversible and can contribute to the capacity fading of the material upon cycling.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75668, "context": "Fig. 6a shows the transfer characteristics of OECTs fabricated with PBTTT with the two different electrolytes. Without DBSA the ON current of the device is \u223c\u221235 \u03bcA at a gate bias of \u22120.8 V and the ON/OFF ratio is \u223c102 with an OFF current \u223c10\u22121 \u03bcA. This is of relatively poor performance, but when DBSA is added to the gating electrolyte it has a huge effect on the ON current which increases to \u22123.1 mA with no change in the ON/OFF ratio. The transconductance, gm increases from 0.05 mS (no DBSA) to 3.9 mS (with DBSA). Again, there is a significant decrease in the operation voltage with a drop in the VON value from 0.35 V to 0.12 V (\u0394VON = 0.23 V) (Fig. S1 for IDS1/2 plots, ESI\u2020). Adding DBSA also has a strong and positive effect on the transient gate bias pulse characteristics (Fig. 6b) as well as the output characteristics of PBTTT (Fig. 6c and d): IDS increases \u223c25 times from \u223c\u2212140 \u03bcA without DBSA to \u223c\u22123.3 mA with DBSA.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75678, "context": "To meet the ever-increasing energy storage demand in electric vehicles and stationary storage systems, a substantial increase in the energy densities of the current Li-ion batteries (LIBs) is essential. This motivates researchers to develop alternate chemistries superior to those based on conventional LiFePO4 and LiCoO2 cathode materials. In this regard, Li\u2013S batteries stand out among their peers because of their high energy capacity. Li\u2013S batteries operate via a conversion based reduction reaction of sulfur (S) with Li (16Li+ + S8 + 16e\u2212 \u2194 8Li2S), leading to an exceptionally high theoretical energy density of \u223c2500 W h kg\u22121\u2014five times more than that of conventional LIBs (387 W h kg\u22121 for LiCoO2/graphite batteries). Additionally, the abundant availability and environment friendly nature of S makes it an attractive cathode material. Despite enormous potential, the practical application of Li\u2013S batteries with liquid electrolyte systems is hindered by issues such as large volumetric changes of S and Li2S (\u223c80%), and the insulating nature of S and Li2Sx. The reduction of S to Li2S during the discharge cycle follows a multistep reduction reaction process, including the formation of highly soluble long-chain polysulfides (Li2Sn, 4 \u2264 n \u2264 8), which are produced as intermediates of this process. Such polysulfides shuttle towards the Li anode which leads to chemical short-circuits and an unstable SEI formation on the Li anode. These polysulfides dry out the liquid electrolyte during long-term cycling which severely affects the performance of the cell. The situation is further complicated by the high loading of S on the cathode (>70% S loading, >3 mgsulfur cm\u22122) during cycling, which intensifies polysulfide dissolution and volume changes, and enforces structural and morphological variations. Overall, such characteristics of the Li\u2013S system result in self-discharge phenomena, poor capacity retention and low coulombic efficiency. On the other hand, the instability of Li anodes with organic liquid electrolytes is also well-known. Li forms mossy or needle like dendritic structures upon cycling which can potentially pierce the conventional polypropylene separators, resulting in internal short circuits of the cells. To solve these problems, various strategies have been explored for both the S and the Li electrodes. For example, synthesizing S composites with carbonaceous materials and/or surface coating the cathodes with conducting polymers have helped in trapping polysulfides. Tuning the properties of organic electrolytes using different additives has been beneficial too. On the Li side, efforts include ex situ coating of Li with polymer- and carbon-based materials or formation of artificial solid\u2013electrolyte interface (SEI) layers to protect the Li electrode from reacting with the organic liquid electrolyte.", "question": "What's the cathode?", "answer": "LiFePO4 ", "answer_start": 303}
{"document_id": 75678, "context": "To meet the ever-increasing energy storage demand in electric vehicles and stationary storage systems, a substantial increase in the energy densities of the current Li-ion batteries (LIBs) is essential. This motivates researchers to develop alternate chemistries superior to those based on conventional LiFePO4 and LiCoO2 cathode materials. In this regard, Li\u2013S batteries stand out among their peers because of their high energy capacity. Li\u2013S batteries operate via a conversion based reduction reaction of sulfur (S) with Li (16Li+ + S8 + 16e\u2212 \u2194 8Li2S), leading to an exceptionally high theoretical energy density of \u223c2500 W h kg\u22121\u2014five times more than that of conventional LIBs (387 W h kg\u22121 for LiCoO2/graphite batteries). Additionally, the abundant availability and environment friendly nature of S makes it an attractive cathode material. Despite enormous potential, the practical application of Li\u2013S batteries with liquid electrolyte systems is hindered by issues such as large volumetric changes of S and Li2S (\u223c80%), and the insulating nature of S and Li2Sx. The reduction of S to Li2S during the discharge cycle follows a multistep reduction reaction process, including the formation of highly soluble long-chain polysulfides (Li2Sn, 4 \u2264 n \u2264 8), which are produced as intermediates of this process. Such polysulfides shuttle towards the Li anode which leads to chemical short-circuits and an unstable SEI formation on the Li anode. These polysulfides dry out the liquid electrolyte during long-term cycling which severely affects the performance of the cell. The situation is further complicated by the high loading of S on the cathode (>70% S loading, >3 mgsulfur cm\u22122) during cycling, which intensifies polysulfide dissolution and volume changes, and enforces structural and morphological variations. Overall, such characteristics of the Li\u2013S system result in self-discharge phenomena, poor capacity retention and low coulombic efficiency. On the other hand, the instability of Li anodes with organic liquid electrolytes is also well-known. Li forms mossy or needle like dendritic structures upon cycling which can potentially pierce the conventional polypropylene separators, resulting in internal short circuits of the cells. To solve these problems, various strategies have been explored for both the S and the Li electrodes. For example, synthesizing S composites with carbonaceous materials and/or surface coating the cathodes with conducting polymers have helped in trapping polysulfides. Tuning the properties of organic electrolytes using different additives has been beneficial too. On the Li side, efforts include ex situ coating of Li with polymer- and carbon-based materials or formation of artificial solid\u2013electrolyte interface (SEI) layers to protect the Li electrode from reacting with the organic liquid electrolyte.", "question": "What's the anode?", "answer": "Li ", "answer_start": 1346}
{"document_id": 75678, "context": "To meet the ever-increasing energy storage demand in electric vehicles and stationary storage systems, a substantial increase in the energy densities of the current Li-ion batteries (LIBs) is essential. This motivates researchers to develop alternate chemistries superior to those based on conventional LiFePO4 and LiCoO2 cathode materials. In this regard, Li\u2013S batteries stand out among their peers because of their high energy capacity. Li\u2013S batteries operate via a conversion based reduction reaction of sulfur (S) with Li (16Li+ + S8 + 16e\u2212 \u2194 8Li2S), leading to an exceptionally high theoretical energy density of \u223c2500 W h kg\u22121\u2014five times more than that of conventional LIBs (387 W h kg\u22121 for LiCoO2/graphite batteries). Additionally, the abundant availability and environment friendly nature of S makes it an attractive cathode material. Despite enormous potential, the practical application of Li\u2013S batteries with liquid electrolyte systems is hindered by issues such as large volumetric changes of S and Li2S (\u223c80%), and the insulating nature of S and Li2Sx. The reduction of S to Li2S during the discharge cycle follows a multistep reduction reaction process, including the formation of highly soluble long-chain polysulfides (Li2Sn, 4 \u2264 n \u2264 8), which are produced as intermediates of this process. Such polysulfides shuttle towards the Li anode which leads to chemical short-circuits and an unstable SEI formation on the Li anode. These polysulfides dry out the liquid electrolyte during long-term cycling which severely affects the performance of the cell. The situation is further complicated by the high loading of S on the cathode (>70% S loading, >3 mgsulfur cm\u22122) during cycling, which intensifies polysulfide dissolution and volume changes, and enforces structural and morphological variations. Overall, such characteristics of the Li\u2013S system result in self-discharge phenomena, poor capacity retention and low coulombic efficiency. On the other hand, the instability of Li anodes with organic liquid electrolytes is also well-known. Li forms mossy or needle like dendritic structures upon cycling which can potentially pierce the conventional polypropylene separators, resulting in internal short circuits of the cells. To solve these problems, various strategies have been explored for both the S and the Li electrodes. For example, synthesizing S composites with carbonaceous materials and/or surface coating the cathodes with conducting polymers have helped in trapping polysulfides. Tuning the properties of organic electrolytes using different additives has been beneficial too. On the Li side, efforts include ex situ coating of Li with polymer- and carbon-based materials or formation of artificial solid\u2013electrolyte interface (SEI) layers to protect the Li electrode from reacting with the organic liquid electrolyte.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75678, "context": "To meet the ever-increasing energy storage demand in electric vehicles and stationary storage systems, a substantial increase in the energy densities of the current Li-ion batteries (LIBs) is essential. This motivates researchers to develop alternate chemistries superior to those based on conventional LiFePO4 and LiCoO2 cathode materials. In this regard, Li\u2013S batteries stand out among their peers because of their high energy capacity. Li\u2013S batteries operate via a conversion based reduction reaction of sulfur (S) with Li (16Li+ + S8 + 16e\u2212 \u2194 8Li2S), leading to an exceptionally high theoretical energy density of \u223c2500 W h kg\u22121\u2014five times more than that of conventional LIBs (387 W h kg\u22121 for LiCoO2/graphite batteries). Additionally, the abundant availability and environment friendly nature of S makes it an attractive cathode material. Despite enormous potential, the practical application of Li\u2013S batteries with liquid electrolyte systems is hindered by issues such as large volumetric changes of S and Li2S (\u223c80%), and the insulating nature of S and Li2Sx. The reduction of S to Li2S during the discharge cycle follows a multistep reduction reaction process, including the formation of highly soluble long-chain polysulfides (Li2Sn, 4 \u2264 n \u2264 8), which are produced as intermediates of this process. Such polysulfides shuttle towards the Li anode which leads to chemical short-circuits and an unstable SEI formation on the Li anode. These polysulfides dry out the liquid electrolyte during long-term cycling which severely affects the performance of the cell. The situation is further complicated by the high loading of S on the cathode (>70% S loading, >3 mgsulfur cm\u22122) during cycling, which intensifies polysulfide dissolution and volume changes, and enforces structural and morphological variations. Overall, such characteristics of the Li\u2013S system result in self-discharge phenomena, poor capacity retention and low coulombic efficiency. On the other hand, the instability of Li anodes with organic liquid electrolytes is also well-known. Li forms mossy or needle like dendritic structures upon cycling which can potentially pierce the conventional polypropylene separators, resulting in internal short circuits of the cells. To solve these problems, various strategies have been explored for both the S and the Li electrodes. For example, synthesizing S composites with carbonaceous materials and/or surface coating the cathodes with conducting polymers have helped in trapping polysulfides. Tuning the properties of organic electrolytes using different additives has been beneficial too. On the Li side, efforts include ex situ coating of Li with polymer- and carbon-based materials or formation of artificial solid\u2013electrolyte interface (SEI) layers to protect the Li electrode from reacting with the organic liquid electrolyte.", "question": "What's the cathode?", "answer": "LiCoO2 ", "answer_start": 315}
{"document_id": 75678, "context": "To meet the ever-increasing energy storage demand in electric vehicles and stationary storage systems, a substantial increase in the energy densities of the current Li-ion batteries (LIBs) is essential. This motivates researchers to develop alternate chemistries superior to those based on conventional LiFePO4 and LiCoO2 cathode materials. In this regard, Li\u2013S batteries stand out among their peers because of their high energy capacity. Li\u2013S batteries operate via a conversion based reduction reaction of sulfur (S) with Li (16Li+ + S8 + 16e\u2212 \u2194 8Li2S), leading to an exceptionally high theoretical energy density of \u223c2500 W h kg\u22121\u2014five times more than that of conventional LIBs (387 W h kg\u22121 for LiCoO2/graphite batteries). Additionally, the abundant availability and environment friendly nature of S makes it an attractive cathode material. Despite enormous potential, the practical application of Li\u2013S batteries with liquid electrolyte systems is hindered by issues such as large volumetric changes of S and Li2S (\u223c80%), and the insulating nature of S and Li2Sx. The reduction of S to Li2S during the discharge cycle follows a multistep reduction reaction process, including the formation of highly soluble long-chain polysulfides (Li2Sn, 4 \u2264 n \u2264 8), which are produced as intermediates of this process. Such polysulfides shuttle towards the Li anode which leads to chemical short-circuits and an unstable SEI formation on the Li anode. These polysulfides dry out the liquid electrolyte during long-term cycling which severely affects the performance of the cell. The situation is further complicated by the high loading of S on the cathode (>70% S loading, >3 mgsulfur cm\u22122) during cycling, which intensifies polysulfide dissolution and volume changes, and enforces structural and morphological variations. Overall, such characteristics of the Li\u2013S system result in self-discharge phenomena, poor capacity retention and low coulombic efficiency. On the other hand, the instability of Li anodes with organic liquid electrolytes is also well-known. Li forms mossy or needle like dendritic structures upon cycling which can potentially pierce the conventional polypropylene separators, resulting in internal short circuits of the cells. To solve these problems, various strategies have been explored for both the S and the Li electrodes. For example, synthesizing S composites with carbonaceous materials and/or surface coating the cathodes with conducting polymers have helped in trapping polysulfides. Tuning the properties of organic electrolytes using different additives has been beneficial too. On the Li side, efforts include ex situ coating of Li with polymer- and carbon-based materials or formation of artificial solid\u2013electrolyte interface (SEI) layers to protect the Li electrode from reacting with the organic liquid electrolyte.", "question": "What's the anode?", "answer": "Li ", "answer_start": 1431}
{"document_id": 75683, "context": "Via this NMR study we identify and quantify some of the key SEI parameters \u2013 namely the lithium ion transport and the rate of healing \u2013 that are important in controlling the nature of lithium metal deposition. Future studies with a much wider range of additives and electrolytes are in progress to use this methodology to help design an optimal SEI layer on lithium metal that achieves uniform plating and stripping at commercially relevant current densities (>0.5 mA cm\u22122) with high coulombic efficiencies.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75659, "context": "Current batteries (especially lithium batteries) have been suffering from a bottleneck in safety issues. For example, these batteries are prone to arouse fires or explosions at extreme temperatures or under external forces, giving rise to significant risks in people's daily lives. Fortunately, the quasi-solid-state COG@MnO2//COG@Zn battery developed in this study exhibits fascinating performance in terms of safety. Firstly, we examined its charge\u2013discharge performance at 60 mA cm\u22123 in a wide temperature range, and the results are shown in Fig. 4d. At room temperature (25 \u00b0C), the battery displays a capacity of 10.3 mA h cm\u22123. When the temperature is decreased to \u221220 \u00b0C, the capacity of the battery decreases to 6.9 mA h cm\u22123. Moreover, when the temperature is raised up to 100 \u00b0C, the battery can still work normally with a capacity of 13.5 mA h cm\u22123. Overall, the capacity of the battery increases gradually and reaches the peak at 80 \u00b0C as the temperature increases from \u221220 to 100 \u00b0C (Fig. 4e). These results indicate that the ion transport through the gel electrolyte is influenced remarkably by the temperature, and the battery can be safely operated in a wide temperature range. Moreover, to evaluate its safety under a variety of extreme conditions, a series of destructive tests were performed on the quasi-solid-state battery. Surprisingly, the battery is still able to power an electronic temperature humidity meter normally even after being damaged under a variety of extreme conditions, such as puncturing, bending, hammering, cutting and cropping (Fig. 4f and Movies S1\u2013S6\u2020), suggesting its superb safety in daily use.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75669, "context": "In situ GIWAXS was used to probe the crystallinity and crystallographic texture of the initial SEI layer formed on copper in 100 ppm added HF electrolyte. The initial SEI, formed by galvanostatically bringing the potential down to 0 V vs. Li/Li+ by cycling at 0.5 mA cm\u22122, was found to contain crystalline LiF particles as evidenced by the small broad peak at 2.71 \u00c5\u22121 in the inset of Fig. 8a, corresponding to the (111) crystallographic plane. These LiF crystallites exhibit (111) texturing as shown by the peaks at \u00b170.5\u00b0 in the I(\u03c7) analysis (Fig. 8b and S5\u2020), which is reasonable given the face centered cubic rock salt structure of LiF. Scherrer analysis of the LiF (111) peak width from the I(q) data indicates a crystallite size on the order of \u223c5 nm, slightly larger than the SEI thickness calculated from both charged passed and XPS depth profiling, suggesting LiF does not form a continuous film. The other SEI components are either amorphous or too thin to characterize with GIWAXS. No crystallographic texture is evident in the SEI formed on copper from an electrolyte without added HF (Fig. S4\u2020). The texturing may only occur in electrolyte with added HF because LiF is formed at higher potential vs. Li/Li+ due to selective HF reduction, and LiF is the only solid product of this reaction. Therefore, the reduction process does not have to compete for reactants (lithium ions, fluorine atoms, electrons) or physical space on the copper surface, resulting in more facile LiF deposition homogenously distributed across the working electrode. In the case without HF, multiple reduction processes (e.g. PF6\u2212, solvent) which yield multiple solid products (e.g. LiF, Li2O, Li2CO3, organic species) all occur simultaneously at the applied scan rates, resulting in more random LiF formation.", "question": "What's the electrolyte?", "answer": "HF ", "answer_start": 139}
{"document_id": 75675, "context": "To further improve the purity of as-obtained H2 gas, a stir-bar was also added inside the electrolyser, and after the ORR continued for \u223c50 min with magnetic stirring at a cell voltage of 0.55 V, the residual O2 gas attached in the corners or dissolved in the electrolytes can effectively be removed; there was no obvious O2 residual peak detected from the GC. Also, the residual O2 gas can simply be removed by degassing the system with a vacuum pump. However, extra energy is required for such a process.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75670, "context": "Directing the morphology of lithium metal deposits during electrodeposition is crucial to the development of safe, high energy density batteries with long cycle life. Towards this end, mechanistic insight is imperative to understand the impact of electrolyte components and cycling conditions on lithium morphologies. In this work, we used a standard carbonate-based electrolyte while systematically adding water (0\u2013250 ppm, corresponding to 0\u2013500 ppm HF) in Li\u2016Cu cells to study the links between electrolyte composition, initial solid electrolyte interphase (SEI) formation, and morphology of electroplated lithium metal using electrochemical characterization, X-ray scattering, X-ray photoelectron spectroscopy, and electron microscopy. Under conditions in which the electrolyte contains several hundred ppm added HF and applied constant currents on the order of 0.5 mA cm\u22122, this system yields electrodeposited lithium metal with a highly monodispersed columnar morphology. Systematic experimental investigation of the HF reduction process, nature of the initial SEI, and the structure of the electrodeposited lithium metal enable insights to be drawn concerning the underlying mechanisms of columnar lithium formation. This morphology arises from an SEI layer comprising crystalline LiF deposits on the copper current collector surface, formed through selective reduction of HF at high potential, embedded in an amorphous matrix of solvent reduction products. This interphase structure contains fast lithium-ion diffusion pathways which lead to a high nucleation density and uniform growth of lithium metal deposits. The mechanism proposed herein will help to inform future electrolyte additive design and formation cycling protocols for lithium metal batteries.", "question": "What's the electrolyte?", "answer": "carbonate-based", "answer_start": 351}
{"document_id": 75802, "context": "The electrochemical test of the Li\u2013CO2 battery was performed by using a 2025 type coin cell with a hole (diameter of 1 cm) on the cathode side. As for the cathode preparation, SiC/RGO and polyvinylidene fluoride (PVDF) were blended in N,N-dimethylformamide with a mass ratio of 9:1 to obtain a slurry. The slurry was uniformly deposited on a circular carbon paper with a diameter of 1 cm, and then dried in a vacuum oven at 80 \u00b0C. The loading mass of the active material was about 0.5 mg for each pellet. Li foil was used as the anode, and a glass fiber was employed as the separator. 1 M LiTFSI dissolved in TEGDME was used as the electrolyte. The battery was assembled in an argon-filled glove box, and then installed into a self-made sealed quartz bottle. The chamber was repeatedly flushed with pure CO2 prior to the measurements to ensure that the gas in the bottle was pure CO2. Each measurement was performed after a 2 h open circuit potential step to ensure equilibrium in the cell. The electrochemical measurements were carried out using a LAND cycler (CT2001A) and an electrochemical workstation (CHI660D, Shanghai Chenhua). A 500 W Xe-lamp was used as the light source for the tests involving light assistance.", "question": "What's the cathode?", "answer": "SiC/RGO and polyvinylidene fluoride (PVDF)", "answer_start": 176}
{"document_id": 75802, "context": "The electrochemical test of the Li\u2013CO2 battery was performed by using a 2025 type coin cell with a hole (diameter of 1 cm) on the cathode side. As for the cathode preparation, SiC/RGO and polyvinylidene fluoride (PVDF) were blended in N,N-dimethylformamide with a mass ratio of 9:1 to obtain a slurry. The slurry was uniformly deposited on a circular carbon paper with a diameter of 1 cm, and then dried in a vacuum oven at 80 \u00b0C. The loading mass of the active material was about 0.5 mg for each pellet. Li foil was used as the anode, and a glass fiber was employed as the separator. 1 M LiTFSI dissolved in TEGDME was used as the electrolyte. The battery was assembled in an argon-filled glove box, and then installed into a self-made sealed quartz bottle. The chamber was repeatedly flushed with pure CO2 prior to the measurements to ensure that the gas in the bottle was pure CO2. Each measurement was performed after a 2 h open circuit potential step to ensure equilibrium in the cell. The electrochemical measurements were carried out using a LAND cycler (CT2001A) and an electrochemical workstation (CHI660D, Shanghai Chenhua). A 500 W Xe-lamp was used as the light source for the tests involving light assistance.", "question": "What's the anode?", "answer": " Li foil ", "answer_start": 504}
{"document_id": 75802, "context": "The electrochemical test of the Li\u2013CO2 battery was performed by using a 2025 type coin cell with a hole (diameter of 1 cm) on the cathode side. As for the cathode preparation, SiC/RGO and polyvinylidene fluoride (PVDF) were blended in N,N-dimethylformamide with a mass ratio of 9:1 to obtain a slurry. The slurry was uniformly deposited on a circular carbon paper with a diameter of 1 cm, and then dried in a vacuum oven at 80 \u00b0C. The loading mass of the active material was about 0.5 mg for each pellet. Li foil was used as the anode, and a glass fiber was employed as the separator. 1 M LiTFSI dissolved in TEGDME was used as the electrolyte. The battery was assembled in an argon-filled glove box, and then installed into a self-made sealed quartz bottle. The chamber was repeatedly flushed with pure CO2 prior to the measurements to ensure that the gas in the bottle was pure CO2. Each measurement was performed after a 2 h open circuit potential step to ensure equilibrium in the cell. The electrochemical measurements were carried out using a LAND cycler (CT2001A) and an electrochemical workstation (CHI660D, Shanghai Chenhua). A 500 W Xe-lamp was used as the light source for the tests involving light assistance.", "question": "What's the electrolyte?", "answer": "1 M LiTFSI dissolved in TEGDME", "answer_start": 585}
{"document_id": 75685, "context": "Inspired by the superior properties of the DBHF fiber cathode, solid-state hybrid batteries were fabricated. As displayed in Fig. 7a and b, a sandwich-type hybrid Zn battery is fabricated based on the DBHF cathode, Zn nanosheets@carbon cloth anode and the gel electrolyte membrane (details in ESI S-4\u2020). Firstly, the stability and flexibility of the fabricated solid state hybrid battery were investigated. As detected in Fig. 7e, good stability in various states, from flat to high degree of bending (Fig. 7g) was achieved during cycling at 2 mA cm\u22122. The charge/discharge profiles of the last cycle at each bending test (Fig. 7h) indicate the two sets of well-retained voltages corresponding to the redox reaction and ORR/OER processes with negligible shape change at different bending degrees. Therefore, the results demonstrate the good stability and excellent flexibility of the prepared hybrid battery. Next, the high-rate performance of the fabricated hybrid battery was investigated at a series of current densities from 2 to 10 mA cm\u22122. Good cycling stabilities were achieved at different current densities (Fig. 7f). The charge voltage gradually increases and the discharge voltage decreases with increased current densities. Even at a high current density of 10 mA cm\u22122, the two sets of charge/discharge voltages are well retained (Fig. 7i), demonstrating its superior high rate capability. Moreover, the flexible hybrid cell exhibits high stability and high efficiency during long-term cycling at the high current density of 6 mA cm\u22122 (Fig. 7j). After five thousand cycles, the flexible hybrid Zn battery achieves well-defined two-set charge/discharge profiles (Fig. 7k), which demonstrate its high stability and high efficiency. Combining the above results, the solid-state hybrid battery exhibits good stability, superior high rate capability and good flexibility in an air environment, where the Zn-ion battery and Zn\u2013air battery work simultaneously.", "question": "What's the cathode?", "answer": " DBHF fiber", "answer_start": 42}
{"document_id": 75685, "context": "Inspired by the superior properties of the DBHF fiber cathode, solid-state hybrid batteries were fabricated. As displayed in Fig. 7a and b, a sandwich-type hybrid Zn battery is fabricated based on the DBHF cathode, Zn nanosheets@carbon cloth anode and the gel electrolyte membrane (details in ESI S-4\u2020). Firstly, the stability and flexibility of the fabricated solid state hybrid battery were investigated. As detected in Fig. 7e, good stability in various states, from flat to high degree of bending (Fig. 7g) was achieved during cycling at 2 mA cm\u22122. The charge/discharge profiles of the last cycle at each bending test (Fig. 7h) indicate the two sets of well-retained voltages corresponding to the redox reaction and ORR/OER processes with negligible shape change at different bending degrees. Therefore, the results demonstrate the good stability and excellent flexibility of the prepared hybrid battery. Next, the high-rate performance of the fabricated hybrid battery was investigated at a series of current densities from 2 to 10 mA cm\u22122. Good cycling stabilities were achieved at different current densities (Fig. 7f). The charge voltage gradually increases and the discharge voltage decreases with increased current densities. Even at a high current density of 10 mA cm\u22122, the two sets of charge/discharge voltages are well retained (Fig. 7i), demonstrating its superior high rate capability. Moreover, the flexible hybrid cell exhibits high stability and high efficiency during long-term cycling at the high current density of 6 mA cm\u22122 (Fig. 7j). After five thousand cycles, the flexible hybrid Zn battery achieves well-defined two-set charge/discharge profiles (Fig. 7k), which demonstrate its high stability and high efficiency. Combining the above results, the solid-state hybrid battery exhibits good stability, superior high rate capability and good flexibility in an air environment, where the Zn-ion battery and Zn\u2013air battery work simultaneously.", "question": "What's the anode?", "answer": "Zn nanosheets@carbon", "answer_start": 215}
{"document_id": 75685, "context": "Inspired by the superior properties of the DBHF fiber cathode, solid-state hybrid batteries were fabricated. As displayed in Fig. 7a and b, a sandwich-type hybrid Zn battery is fabricated based on the DBHF cathode, Zn nanosheets@carbon cloth anode and the gel electrolyte membrane (details in ESI S-4\u2020). Firstly, the stability and flexibility of the fabricated solid state hybrid battery were investigated. As detected in Fig. 7e, good stability in various states, from flat to high degree of bending (Fig. 7g) was achieved during cycling at 2 mA cm\u22122. The charge/discharge profiles of the last cycle at each bending test (Fig. 7h) indicate the two sets of well-retained voltages corresponding to the redox reaction and ORR/OER processes with negligible shape change at different bending degrees. Therefore, the results demonstrate the good stability and excellent flexibility of the prepared hybrid battery. Next, the high-rate performance of the fabricated hybrid battery was investigated at a series of current densities from 2 to 10 mA cm\u22122. Good cycling stabilities were achieved at different current densities (Fig. 7f). The charge voltage gradually increases and the discharge voltage decreases with increased current densities. Even at a high current density of 10 mA cm\u22122, the two sets of charge/discharge voltages are well retained (Fig. 7i), demonstrating its superior high rate capability. Moreover, the flexible hybrid cell exhibits high stability and high efficiency during long-term cycling at the high current density of 6 mA cm\u22122 (Fig. 7j). After five thousand cycles, the flexible hybrid Zn battery achieves well-defined two-set charge/discharge profiles (Fig. 7k), which demonstrate its high stability and high efficiency. Combining the above results, the solid-state hybrid battery exhibits good stability, superior high rate capability and good flexibility in an air environment, where the Zn-ion battery and Zn\u2013air battery work simultaneously.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75685, "context": "Inspired by the superior properties of the DBHF fiber cathode, solid-state hybrid batteries were fabricated. As displayed in Fig. 7a and b, a sandwich-type hybrid Zn battery is fabricated based on the DBHF cathode, Zn nanosheets@carbon cloth anode and the gel electrolyte membrane (details in ESI S-4\u2020). Firstly, the stability and flexibility of the fabricated solid state hybrid battery were investigated. As detected in Fig. 7e, good stability in various states, from flat to high degree of bending (Fig. 7g) was achieved during cycling at 2 mA cm\u22122. The charge/discharge profiles of the last cycle at each bending test (Fig. 7h) indicate the two sets of well-retained voltages corresponding to the redox reaction and ORR/OER processes with negligible shape change at different bending degrees. Therefore, the results demonstrate the good stability and excellent flexibility of the prepared hybrid battery. Next, the high-rate performance of the fabricated hybrid battery was investigated at a series of current densities from 2 to 10 mA cm\u22122. Good cycling stabilities were achieved at different current densities (Fig. 7f). The charge voltage gradually increases and the discharge voltage decreases with increased current densities. Even at a high current density of 10 mA cm\u22122, the two sets of charge/discharge voltages are well retained (Fig. 7i), demonstrating its superior high rate capability. Moreover, the flexible hybrid cell exhibits high stability and high efficiency during long-term cycling at the high current density of 6 mA cm\u22122 (Fig. 7j). After five thousand cycles, the flexible hybrid Zn battery achieves well-defined two-set charge/discharge profiles (Fig. 7k), which demonstrate its high stability and high efficiency. Combining the above results, the solid-state hybrid battery exhibits good stability, superior high rate capability and good flexibility in an air environment, where the Zn-ion battery and Zn\u2013air battery work simultaneously.", "question": "What's the cathode?", "answer": "DBHF", "answer_start": 201}
{"document_id": 75690, "context": "To test the differences in Li deposition between the two electrolytes further, in situ NMR measurements using pulsed currents were carried out. When applying a pulsed current, short pulses for a period TON are applied, which is followed by a rest period TOFF where no current is passed (schematic, Fig. S5\u2020). During the rest period, TOFF, two main processes occur:", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75695, "context": "Nanostructuring of electrodes is a known method for increasing the power density of lithium-ion (Li-ion) batteries. This can happen because of the much shorter characteristic diffusion times of ions and electrons in nanometer-thick active materials compared to the typical micron-sized active particles. Nanostructured active materials also exhibit a higher contact area with the electrode components supplying ions (the electrolyte) and electrons (the current collector and conductive additives) to the active redox sites. As a result, the time required for fully charging and discharging the electrodes can be shortened from hours to as little as a few seconds.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75700, "context": "Aiming to achieve higher energy batteries, researchers have started to revisit the LiNiO2 chemistry with hopes that knowledge obtained from NMC and NCA studies could be applied to LiNiO2 and resolve the issues that were identified decades ago. Furthermore, eliminating the use of cobalt can circumvent the issues surrounding Co such as high toxicity, high cost, and child labor abuse in mining. At the material level, the most popular strategy is the bulk cationic doping to enhance the electrochemical reversibility. With doping strategies, Co-free Ni-rich layered cathode materials are expected to deliver comparable battery performance to NMCs and NCAs. In addition, many studies have been performed on modulating the electrolyte composition to improve the electrode\u2013electrolyte interphase for stabilizing the battery performance. The surface of LiNiO2-based materials is much more reactive than NMC and NCA materials owing to the extreme Ni3+/Ni4+ redox couple. Thus, revealing the origins of surface changes can better inform the advanced design of promising LiNiO2-based materials. At present, most studies rely on ex situ characterization methods to understand the surface degradation of cathode materials, for example, transition electron microscopy (TEM) based techniques for atomic scale structural and chemical analysis, as well as surface sensitive X-ray spectroscopy for ensemble-averaged measurements to probe surface chemical information. The surface sensitive probing techniques typically have low penetrating depths, which makes it difficult to study surface chemistry under practical battery operating environments. Noticeably, the chemical and structural information on the particle surface may be influenced by a range of experimental conditions, including but not limited to, human exhalation, sample storage, and sample preparation during material surface analysis. This can skew observations found in characterization analysis, surface doping, and electrochemical protocol. Therefore, to characterize the surface of LiNiO2 properly, one must understand how the experimental conditions influence overall surface and interfacial chemistries.", "question": "What's the cathode?", "answer": "Co-free Ni-rich", "answer_start": 542}
{"document_id": 75700, "context": "Aiming to achieve higher energy batteries, researchers have started to revisit the LiNiO2 chemistry with hopes that knowledge obtained from NMC and NCA studies could be applied to LiNiO2 and resolve the issues that were identified decades ago. Furthermore, eliminating the use of cobalt can circumvent the issues surrounding Co such as high toxicity, high cost, and child labor abuse in mining. At the material level, the most popular strategy is the bulk cationic doping to enhance the electrochemical reversibility. With doping strategies, Co-free Ni-rich layered cathode materials are expected to deliver comparable battery performance to NMCs and NCAs. In addition, many studies have been performed on modulating the electrolyte composition to improve the electrode\u2013electrolyte interphase for stabilizing the battery performance. The surface of LiNiO2-based materials is much more reactive than NMC and NCA materials owing to the extreme Ni3+/Ni4+ redox couple. Thus, revealing the origins of surface changes can better inform the advanced design of promising LiNiO2-based materials. At present, most studies rely on ex situ characterization methods to understand the surface degradation of cathode materials, for example, transition electron microscopy (TEM) based techniques for atomic scale structural and chemical analysis, as well as surface sensitive X-ray spectroscopy for ensemble-averaged measurements to probe surface chemical information. The surface sensitive probing techniques typically have low penetrating depths, which makes it difficult to study surface chemistry under practical battery operating environments. Noticeably, the chemical and structural information on the particle surface may be influenced by a range of experimental conditions, including but not limited to, human exhalation, sample storage, and sample preparation during material surface analysis. This can skew observations found in characterization analysis, surface doping, and electrochemical protocol. Therefore, to characterize the surface of LiNiO2 properly, one must understand how the experimental conditions influence overall surface and interfacial chemistries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75705, "context": "The critical property of anode materials is coulombic efficiency. CE at the first cycle is particularly significant since it usually leads to the highest capacity losses due to SEI formation and other irreversible reduction processes. As shown in Chart 5e, a relatively high 1st cycle CE (>60%) is observed for carboxylates, carbonyls 10 and 21, as well as for P30, P31, and P32. For other materials, as well as for some inorganic benchmarks (carbons with a high surface area, phosphorous, FeS2), the CE is even lower. It should be noted that the CE depends not only on the material but also on the electrolyte composition. The tuning of the electrolyte is rarely reported. Some studies indicate that using ether-based electrolytes, such as KPF6 in DME, improves the CE. More attention should be paid to the electrolyte optimization, particularly for the materials that showed low CE with the carbonate-based solutions.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75705, "context": "The critical property of anode materials is coulombic efficiency. CE at the first cycle is particularly significant since it usually leads to the highest capacity losses due to SEI formation and other irreversible reduction processes. As shown in Chart 5e, a relatively high 1st cycle CE (>60%) is observed for carboxylates, carbonyls 10 and 21, as well as for P30, P31, and P32. For other materials, as well as for some inorganic benchmarks (carbons with a high surface area, phosphorous, FeS2), the CE is even lower. It should be noted that the CE depends not only on the material but also on the electrolyte composition. The tuning of the electrolyte is rarely reported. Some studies indicate that using ether-based electrolytes, such as KPF6 in DME, improves the CE. More attention should be paid to the electrolyte optimization, particularly for the materials that showed low CE with the carbonate-based solutions.", "question": "What's the electrolyte?", "answer": "KPF6 in DME", "answer_start": 741}
{"document_id": 75686, "context": "\u2022 Enhancing affinity toward LiPSs promotes surface conversion to decrease the total amount of soluble LiPSs in the electrolyte, thereby ensuring shuttle suppression and high capacity. Metal sulfides with a high surface area, well-designed porosity, enhanced surface polar (functional or defective surface), desired surface selectivity (exposed crystal faces), and tailored crystalline form are a high-priority target.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75696, "context": "In this study, three types of electrolytes were prepared for investigation: 1.0 M LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC, 1:1 v/v, marked as LPE-EC), 1.0 M LiPF6 in propylene carbonate/diethyl carbonate (PC/DEC, 1:1 v/v, marked as LPE-PC), and 1.0 M LiPF6 in PC/DEC (1:1 v/v, with 0.005 M LiBOB, marked as LPE-PC\u2013LiBOB). All the electrolytes were prepared in an argon-filled glove box.", "question": "What's the electrolyte?", "answer": "1.0 M LiPF6 in ethylene carbonate/diethyl carbonate ", "answer_start": 76}
{"document_id": 75696, "context": "In this study, three types of electrolytes were prepared for investigation: 1.0 M LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC, 1:1 v/v, marked as LPE-EC), 1.0 M LiPF6 in propylene carbonate/diethyl carbonate (PC/DEC, 1:1 v/v, marked as LPE-PC), and 1.0 M LiPF6 in PC/DEC (1:1 v/v, with 0.005 M LiBOB, marked as LPE-PC\u2013LiBOB). All the electrolytes were prepared in an argon-filled glove box.", "question": "What's the electrolyte?", "answer": "1.0 M LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC, 1:1 v/v, marked as LPE-EC), 1.0 M LiPF6 in propylene carbonate/diethyl carbonate (PC/DEC, 1:1 v/v, marked as LPE-PC), and 1.0 M LiPF6 in PC/DEC (1:1 v/v, with 0.005 M LiBOB, marked as LPE-PC\u2013LiBOB)", "answer_start": 76}
{"document_id": 75701, "context": "Moreover, cycling stability is a very important parameter of the electrochromic films in practical applications. We have measured the CV curves for more than 200 cycles from \u22120.6 to 0.9 V. In each cycle, the reversible process of coloring and bleaching can be observed in the annealed WO3\u2212x film. Fig. 4d shows the CV curves for the first, 50th, 100th, 150th and 200th cycle. The CV curves in the first 50 cycles show slight promotion, and remain almost stable without any degradation even after 200 cycles. Such a high cycling stability may originate from the solid nanostructure of the annealed WO3\u2212x film and the prevention of the harmful side reaction at the WO3\u2212x film/electrolyte interface.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75706, "context": "For dual-ion batteries, increasing Qm is also principally possible by, for example, increasing the concentration of redox-active nitrogen atoms in aromatic amines. For such optimized materials, where most of the active units are involved, it is expected that the operation potentials will get higher at least for conjugated structures because polymers with a high positive charge at the backbone are harder to oxidize. It will therefore be important to develop electrolytes for potassium batteries, which are tolerant to high voltages, or to elaborate protective coatings at the cathode surface. Certain progress in the development of high-voltage potassium battery electrolytes has already been achieved.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75706, "context": "For dual-ion batteries, increasing Qm is also principally possible by, for example, increasing the concentration of redox-active nitrogen atoms in aromatic amines. For such optimized materials, where most of the active units are involved, it is expected that the operation potentials will get higher at least for conjugated structures because polymers with a high positive charge at the backbone are harder to oxidize. It will therefore be important to develop electrolytes for potassium batteries, which are tolerant to high voltages, or to elaborate protective coatings at the cathode surface. Certain progress in the development of high-voltage potassium battery electrolytes has already been achieved.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75711, "context": "To address the challenges facing Li\u2013S batteries, considerable efforts have been made to develop sulfur-based cathode composite materials, modify separators, protect Li anodes, and use conductive interlayers and/or novel electrolyte additives (Fig. 1b). These approaches have all yielded certain encouraging results. However, the above strategies often have variable effects on the performance of Li\u2013S batteries, owing to the specificity and interdependency of the S8\u2013Li2Sn\u2013Li2S (solid\u2013liquid\u2013solid) multistage transformation. For example, the conductive interlayer introduced between the separator and cathode suppresses the migration of LiPSs, which also offers additional electron pathways that cover the top surface of the cathode. This performance enhances the use of active materials and reduces random deposition of Li2S on the surface of the Li anode, thereby restraining dendrite formation and improving the anode stability to a certain degree.", "question": "What's the cathode?", "answer": "sulfur-based", "answer_start": 96}
{"document_id": 75711, "context": "To address the challenges facing Li\u2013S batteries, considerable efforts have been made to develop sulfur-based cathode composite materials, modify separators, protect Li anodes, and use conductive interlayers and/or novel electrolyte additives (Fig. 1b). These approaches have all yielded certain encouraging results. However, the above strategies often have variable effects on the performance of Li\u2013S batteries, owing to the specificity and interdependency of the S8\u2013Li2Sn\u2013Li2S (solid\u2013liquid\u2013solid) multistage transformation. For example, the conductive interlayer introduced between the separator and cathode suppresses the migration of LiPSs, which also offers additional electron pathways that cover the top surface of the cathode. This performance enhances the use of active materials and reduces random deposition of Li2S on the surface of the Li anode, thereby restraining dendrite formation and improving the anode stability to a certain degree.", "question": "What's the anode?", "answer": "Li", "answer_start": 165}
{"document_id": 75711, "context": "To address the challenges facing Li\u2013S batteries, considerable efforts have been made to develop sulfur-based cathode composite materials, modify separators, protect Li anodes, and use conductive interlayers and/or novel electrolyte additives (Fig. 1b). These approaches have all yielded certain encouraging results. However, the above strategies often have variable effects on the performance of Li\u2013S batteries, owing to the specificity and interdependency of the S8\u2013Li2Sn\u2013Li2S (solid\u2013liquid\u2013solid) multistage transformation. For example, the conductive interlayer introduced between the separator and cathode suppresses the migration of LiPSs, which also offers additional electron pathways that cover the top surface of the cathode. This performance enhances the use of active materials and reduces random deposition of Li2S on the surface of the Li anode, thereby restraining dendrite formation and improving the anode stability to a certain degree.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75711, "context": "To address the challenges facing Li\u2013S batteries, considerable efforts have been made to develop sulfur-based cathode composite materials, modify separators, protect Li anodes, and use conductive interlayers and/or novel electrolyte additives (Fig. 1b). These approaches have all yielded certain encouraging results. However, the above strategies often have variable effects on the performance of Li\u2013S batteries, owing to the specificity and interdependency of the S8\u2013Li2Sn\u2013Li2S (solid\u2013liquid\u2013solid) multistage transformation. For example, the conductive interlayer introduced between the separator and cathode suppresses the migration of LiPSs, which also offers additional electron pathways that cover the top surface of the cathode. This performance enhances the use of active materials and reduces random deposition of Li2S on the surface of the Li anode, thereby restraining dendrite formation and improving the anode stability to a certain degree.", "question": "What's the anode?", "answer": "Li ", "answer_start": 849}
{"document_id": 75702, "context": "In summary, it's proposed that stacking few-layer Nb2CTx with Ti3C2Tx nanosheets into composite structures is a simple and effective approach to improve the electrochemical performance of Nb2CTx-based films for supercapacitors. The intercalated Ti3C2Tx nanosheets between Nb2CTx layers effectively increase the interlayer spacing of Nb2CTx layers and impede the self-restacking of Nb2CTx nanosheets, which are favorable for electrolyte ions to rapidly diffuse and transport in the hybrid electrodes. The optimized Ti3C2Tx/Nb2CTx films possess enhanced capacitive performance and rate performance. A gravimetric capacitance of 370 F g\u22121 can be delivered at 2 mV s\u22121 and 56.1% capacitance retention at a high scan rate of 200 mV s\u22121. The energy density of the assembled all-solid-state supercapacitors can reach 5.5 mW h g\u22121 at a power density of 141.4 mW g\u22121, and 1.1 mW h g\u22121 at a high power density of 2350.0 mW g\u22121. The all-solid-state supercapacitors presented good flexibility and long cycling life. The all-solid-state supercapacitor was also integrated with a flex sensor to fabricate a self-powered device, where the all-solid-state supercapacitor served as a stable power source unit to drive the flex sensor. The route to fabricate Ti3C2Tx/Nb2CTx hybrid films is also applicable for other M2CTx MXenes, for example, Ti2CTx and V2CTx, improving the application potential of MXenes in flexible supercapacitors and integrated electronic devices.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75712, "context": "Nowadays, carbon nanomaterials are considered as the most important supercapacitor electrode materials. But it's still a great challenge to design rational structures of carbon materials at both nano and micro scales to endow carbon electrode materials with outstanding electrochemical performance. Herein, a well-designed compressible and elastic N-doped porous carbon nanofiber aerogel (N-PCNFA) with hierarchical cellular structures in both the PAN/ZIF-8-based carbon nanofibers and the 3D carbon monolith was prepared by a simple method. A large specific surface area was obtained for the construction of abundant pore structures and a robust architecture was built by the introduction of mechanically reinforced structures, which would endow the N-PCNFA electrode material with a vast surface area for ion adsorption/desorption, plenty of short channels for electrolyte diffusion and stable frameworks during the charge/discharge process. N heteroatoms were also incorporated into the carbon material as active sites for faradaic redox reactions. Thus, the N-PCNFA electrodes exhibited superior electrochemical performance, with a high specific capacitance of 279 F g\u22121 at 0.5 A g\u22121, consisting of pseudocapacitance (\u223c46%) and electrochemical double-layer capacitance (\u223c54%), remarkable rate performance of 59% at 20 A g\u22121 and excellent long-term durability. Moreover, the simple and general strategy for construction of compressible and elastic porous carbon nanofiber aerogels with delicate microstructures is also applicable to other advanced functional materials for a wide range of applications.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75697, "context": "The mechanism of the one-cell, two-electrode decoupled water splitting using Ni(OH)2 as the relay is shown in Fig. 1a. For the H2 evolution step, H2O is reduced on the GEE and the Ni(OH)2 electrode is oxidized to NiOOH simultaneously. By reversing the current polarity, O2 is produced on the GEE by an anodic oxidation of OH\u2212; meanwhile the NiOOH electrode is reduced to Ni(OH)2. The cyclic voltammogram (CV) curve of the Ni(OH)2 electrode tested at a scan rate of 1 mV s\u22121 using Ag/AgCl as the reference electrode is shown in Fig. 1b. One pair of redox peaks located at 0.423 V/0.238 V (vs. Ag/AgCl) can be indexed to the reversible Ni(OH)2/NiOOH processes, which is consistent with the potential of the Ni(OH)2 electrode in the HER and OER processes. In operation, the one-cell, two-electrode design requires a cell voltage of 0.17 V for the OER step and 1.52 V for the HER step (Fig. 1c). The different operating voltages of the cell for HER and OER steps are caused by the redox potential of the RE (NiOOH/Ni(OH)2), which is much closer to the potential for the OER than the HER. As shown in Fig. 1d, at a cell current of 100 mA, the two-step water splitting process can be reversibly cycled for 24 rounds in 8 hours without noticeable decay. The duration for each OER and HER step was 10 min and the duration can be extended up to 3.5 h before the RE was fully consumed (Fig. S6\u2020). Interestingly, in each gas evolution cycle, after the OER step, there is always a potential drop in the following HER step (inset in Fig. 1d). Meanwhile the HER process does not show this kind of peak. Since the ORR requires lower potential than the HER, after the OER step, there is residual O2 trapped on the GEE or dissolved in the electrolyte, and the ORR occurs to consume this O2, which temporarily reduces the cell voltage.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75703, "context": "In summary, we developed a formation method of a Li protective artificial SEI layer to form a LiF and polymeric composite protection layer directly on lithium metal foil using the electrochemical reaction between the Li and the sacrificial PTFE film by using roll-pressing. The roll-press process is facile, cost-effective, eco-friendly and a mass and large-area scalable process. The composite protection layer composed of a LiF-rich layer and polyene/unsaturated fluoropolymer rich layer could significantly improve the electrochemical properties of LMBs. The LiF@Po protection layer provides a stable interface between the Li metal and the electrolyte, enabling improved Li plating/stripping behavior and ultra-long cycling stability in both the Li\u2016Li symmetric cell and Li\u2016LCO/Li\u2016NCM full cells. In particular, the full cell with the NCM-811 cathode and LiF@Po\u2013Li anode exhibits reasonable electrochemical performance even with transition metal dissolution. The material design strategies presented here could provide important avenues for forming an artificial SEI layer in various applications not only in Li metal systems but also in other metal systems including sodium and potassium.", "question": "What's the cathode?", "answer": "NCM-811", "answer_start": 838}
{"document_id": 75703, "context": "In summary, we developed a formation method of a Li protective artificial SEI layer to form a LiF and polymeric composite protection layer directly on lithium metal foil using the electrochemical reaction between the Li and the sacrificial PTFE film by using roll-pressing. The roll-press process is facile, cost-effective, eco-friendly and a mass and large-area scalable process. The composite protection layer composed of a LiF-rich layer and polyene/unsaturated fluoropolymer rich layer could significantly improve the electrochemical properties of LMBs. The LiF@Po protection layer provides a stable interface between the Li metal and the electrolyte, enabling improved Li plating/stripping behavior and ultra-long cycling stability in both the Li\u2016Li symmetric cell and Li\u2016LCO/Li\u2016NCM full cells. In particular, the full cell with the NCM-811 cathode and LiF@Po\u2013Li anode exhibits reasonable electrochemical performance even with transition metal dissolution. The material design strategies presented here could provide important avenues for forming an artificial SEI layer in various applications not only in Li metal systems but also in other metal systems including sodium and potassium.", "question": "What's the anode?", "answer": "LiF@Po\u2013Li", "answer_start": 858}
{"document_id": 75703, "context": "In summary, we developed a formation method of a Li protective artificial SEI layer to form a LiF and polymeric composite protection layer directly on lithium metal foil using the electrochemical reaction between the Li and the sacrificial PTFE film by using roll-pressing. The roll-press process is facile, cost-effective, eco-friendly and a mass and large-area scalable process. The composite protection layer composed of a LiF-rich layer and polyene/unsaturated fluoropolymer rich layer could significantly improve the electrochemical properties of LMBs. The LiF@Po protection layer provides a stable interface between the Li metal and the electrolyte, enabling improved Li plating/stripping behavior and ultra-long cycling stability in both the Li\u2016Li symmetric cell and Li\u2016LCO/Li\u2016NCM full cells. In particular, the full cell with the NCM-811 cathode and LiF@Po\u2013Li anode exhibits reasonable electrochemical performance even with transition metal dissolution. The material design strategies presented here could provide important avenues for forming an artificial SEI layer in various applications not only in Li metal systems but also in other metal systems including sodium and potassium.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75709, "context": "To evaluate the performances of 2D GeP nanosheet-based photodetectors at an exact wavelength, selected wavelengths of lights (350, 365, 380, 400, 475, 550 and 650 nm) were employed (Fig. 4) in 0.1, 0.5 and 1 M KOH electrolytes. It is clear to see that the photocurrent density values are greatly smaller than the values under simulated light because of inferior light irradiation. The photocurrent density and photoresponsivity show a similar trend to the results in a simulated light state. Notably, it is also shown that such 2D GeP nanosheet-based photodetectors exhibit a higher sensitivity at a short wavelength range, especially at 350, 365 and 380 nm (Fig. 4c, f and i) and the highest photoresponsivity is 187.5 \u03bcA W\u22121 at 380 nm wavelength, 0.6 V applied bias potential and in 0.5 M KOH electrolyte. The above photo-response results at different wavelengths are in strong agreement with the UV-Vis absorption spectrum in Fig. 1g. Such results demonstrate great potential for high-performance UV-Vis photodetector application.", "question": "What's the electrolyte?", "answer": "0.1, 0.5 and 1 M KOH", "answer_start": 193}
{"document_id": 75709, "context": "To evaluate the performances of 2D GeP nanosheet-based photodetectors at an exact wavelength, selected wavelengths of lights (350, 365, 380, 400, 475, 550 and 650 nm) were employed (Fig. 4) in 0.1, 0.5 and 1 M KOH electrolytes. It is clear to see that the photocurrent density values are greatly smaller than the values under simulated light because of inferior light irradiation. The photocurrent density and photoresponsivity show a similar trend to the results in a simulated light state. Notably, it is also shown that such 2D GeP nanosheet-based photodetectors exhibit a higher sensitivity at a short wavelength range, especially at 350, 365 and 380 nm (Fig. 4c, f and i) and the highest photoresponsivity is 187.5 \u03bcA W\u22121 at 380 nm wavelength, 0.6 V applied bias potential and in 0.5 M KOH electrolyte. The above photo-response results at different wavelengths are in strong agreement with the UV-Vis absorption spectrum in Fig. 1g. Such results demonstrate great potential for high-performance UV-Vis photodetector application.", "question": "What's the electrolyte?", "answer": "0.5 M KOH", "answer_start": 785}
{"document_id": 75704, "context": "The detailed preparation processes of positive electrodes can be found in previous work. The mass loading of active material was \u223c3.0 mg cm\u22122 for positive electrodes. In 2032-type half cells, lithium foil was used as the anode. Pre-lithiated MCMB was utilized as the negative electrode in full cells. The electrolyte was 1 M LiPF6 dissolved in mixed solvents of DMC and EC (7:3 by volume). Galvanostatic charge\u2013discharge was conducted using a LAND tester (CT-2001A). All electrochemical testing was performed at room temperature (25 \u00b0C).", "question": "What's the anode?", "answer": "lithium foil", "answer_start": 192}
{"document_id": 75704, "context": "The detailed preparation processes of positive electrodes can be found in previous work. The mass loading of active material was \u223c3.0 mg cm\u22122 for positive electrodes. In 2032-type half cells, lithium foil was used as the anode. Pre-lithiated MCMB was utilized as the negative electrode in full cells. The electrolyte was 1 M LiPF6 dissolved in mixed solvents of DMC and EC (7:3 by volume). Galvanostatic charge\u2013discharge was conducted using a LAND tester (CT-2001A). All electrochemical testing was performed at room temperature (25 \u00b0C).", "question": "What's the electrolyte?", "answer": "1 M LiPF6", "answer_start": 321}
{"document_id": 75708, "context": "The stretchability was also tested through stretching the developed spring ssZIBs. First, a spring solid-state battery was prepared by sealing the cathode, anode, and CNF\u2013PAM hydrogel electrolyte in a spring-type plastic tube. As shown in Fig. 3i, a digital clock was powered by the developed blue spring solid-state battery. As shown by the figure in Fig. 3j and k and the video provided in ESI III and IV,\u2020 the spring solid-state battery still worked well under repeated tension and contraction. This demonstrates the robust stability, high stretchability and flexibility of our ssZIBs.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75708, "context": "The stretchability was also tested through stretching the developed spring ssZIBs. First, a spring solid-state battery was prepared by sealing the cathode, anode, and CNF\u2013PAM hydrogel electrolyte in a spring-type plastic tube. As shown in Fig. 3i, a digital clock was powered by the developed blue spring solid-state battery. As shown by the figure in Fig. 3j and k and the video provided in ESI III and IV,\u2020 the spring solid-state battery still worked well under repeated tension and contraction. This demonstrates the robust stability, high stretchability and flexibility of our ssZIBs.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75708, "context": "The stretchability was also tested through stretching the developed spring ssZIBs. First, a spring solid-state battery was prepared by sealing the cathode, anode, and CNF\u2013PAM hydrogel electrolyte in a spring-type plastic tube. As shown in Fig. 3i, a digital clock was powered by the developed blue spring solid-state battery. As shown by the figure in Fig. 3j and k and the video provided in ESI III and IV,\u2020 the spring solid-state battery still worked well under repeated tension and contraction. This demonstrates the robust stability, high stretchability and flexibility of our ssZIBs.", "question": "What's the electrolyte?", "answer": "CNF\u2013PAM hydrogel", "answer_start": 167}
{"document_id": 75713, "context": "Flexible lithium-ion batteries have attracted extensive attentions in electronics. However, their practical applications are primarily limited by low open-circuit voltage and energy density. Herein, we report a novel surface/interface modification strategy to obtain electrolyte-phobic carbon nanotube film as the flexible current collector for foldable lithium-ion batteries. The as-assembled battery exhibits a high open-circuit voltage of 4.04 V and energy density of ~293 Wh kg-1 with excellent flexibility and stable cycle performance. The outstanding performance is ascribed to the electrolyte-phobic surface/interfacial layer of carbon nanotube film, which restrains the intercalation of lithium ions into carbon-based current collector. This work not only demonstrates a practical solution to appreciably revamp the voltage and energy density of flexible lithium-ion batteries, but more importantly, offers valuable insights in modifying the surface/interface chemistry of carbon-based current collectors for high-performance energy storage devices.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75723, "context": "The slurry for the electrocatalytic study was prepared by dispersing 10 mg active material and 5 mg Super P carbon in 250 \u03bcL isopropyl alcohol and 750 \u03bcL distilled water. After sonicating the solution for 15 minutes, 5 \u03bcL Nafion binder was added followed by further sonication for 30 minutes. Then, 5 \u03bcL of the slurry was drop-casted on a glassy carbon rotating ring disc electrode (RRDE). The electrocatalytic study was carried out at room temperature using a CH instrument (CHI700E) bipotentiostat using 0.1 M KOH as the electrolyte.", "question": "What's the electrolyte?", "answer": "0.1 M KOH ", "answer_start": 506}
{"document_id": 75722, "context": "For the first time, DBHF nanofibers are constructed as flexible cathodes for HZBs. The formation mechanism of the DBHF structure is probed and the relationships between the synthetic conditions and the structures of the products are carefully investigated. Moreover, the HZBs are fabricated based on the DBHF cathode, Zn nanosheet@carbon cloth anode and a polymer electrolyte. Benefitting from the unique structure, the hybrid battery achieves high energy/power density and long-term cycling stability. Moreover, the high flexibility and \u201cair-charging\u201d capability make it a good uninterrupted power source for flexible electronics in different environments (Fig. 1h and i).", "question": "What's the cathode?", "answer": "DBHF nanofibers", "answer_start": 20}
{"document_id": 75722, "context": "For the first time, DBHF nanofibers are constructed as flexible cathodes for HZBs. The formation mechanism of the DBHF structure is probed and the relationships between the synthetic conditions and the structures of the products are carefully investigated. Moreover, the HZBs are fabricated based on the DBHF cathode, Zn nanosheet@carbon cloth anode and a polymer electrolyte. Benefitting from the unique structure, the hybrid battery achieves high energy/power density and long-term cycling stability. Moreover, the high flexibility and \u201cair-charging\u201d capability make it a good uninterrupted power source for flexible electronics in different environments (Fig. 1h and i).", "question": "What's the anode?", "answer": "Zn nanosheet@carbon", "answer_start": 318}
{"document_id": 75722, "context": "For the first time, DBHF nanofibers are constructed as flexible cathodes for HZBs. The formation mechanism of the DBHF structure is probed and the relationships between the synthetic conditions and the structures of the products are carefully investigated. Moreover, the HZBs are fabricated based on the DBHF cathode, Zn nanosheet@carbon cloth anode and a polymer electrolyte. Benefitting from the unique structure, the hybrid battery achieves high energy/power density and long-term cycling stability. Moreover, the high flexibility and \u201cair-charging\u201d capability make it a good uninterrupted power source for flexible electronics in different environments (Fig. 1h and i).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75722, "context": "For the first time, DBHF nanofibers are constructed as flexible cathodes for HZBs. The formation mechanism of the DBHF structure is probed and the relationships between the synthetic conditions and the structures of the products are carefully investigated. Moreover, the HZBs are fabricated based on the DBHF cathode, Zn nanosheet@carbon cloth anode and a polymer electrolyte. Benefitting from the unique structure, the hybrid battery achieves high energy/power density and long-term cycling stability. Moreover, the high flexibility and \u201cair-charging\u201d capability make it a good uninterrupted power source for flexible electronics in different environments (Fig. 1h and i).", "question": "What's the cathode?", "answer": "DBHF", "answer_start": 304}
{"document_id": 75727, "context": "To gain more insight into the morphological changes on the electrodes, as well as the causes of mNMR < mechem, we performed spectral fittings to determine how the relative fractions of the peaks assigned to Li microstructures vs. \u201cbulk metal\u201d change upon plating. The spectra were deconvoluted by using two peaks around 245\u2013252.5 ppm (\u201cbulk metal\u201d) and one peak at around 257.5\u2013262.5 ppm corresponding to the microstructural peak (see an example in Fig. 2f and more detailed explanation in the ESI\u2020). We note that previous work has shown both experimentally and with simulations that dendrites and structures growing away from the Li metal surface give rise to larger shift around 270 ppm compared to microstructures close to the surface. In the current study, the in situ PEEK capsule cell applies constant pressure within the cell and more compact structures form, leading to a narrower range of shifts. The observed shifts of the microstructure peaks (Fig. S1\u2020) are thus similar for both electrolytes although the microstructures have very distinct morphologies as seen in the SEM figures (Fig. 2b).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75736, "context": "For small molecules, making composites with conductive fillers is one of the main strategies to enhance the rate capability. Decreasing the particle size, e.g., via ball-milling, is apparently another effective approach. Conjugated polymers should have better electron conductivity and potentially perform better than non-conductive small molecules. However, the performance of reported conjugated structures was generally moderate. We suppose that this is partly because non-optimal carbonate-based electrolytes were used with these materials.", "question": "What's the electrolyte?", "answer": "carbonate-based ", "answer_start": 484}
{"document_id": 75742, "context": "The ITO-coated glass samples were cleaned with acetone, ethanol, and isopropanol, sequentially. The vacant assemblies were prepared by using two ITO-coated glass samples with and without WO3 layers, respectively, which were stacked with a 60 \u03bcm-thick Surlyn adhesive film. Then, two electrolyte inlets were drilled into the ITO-coated glass side without the WO3 layer. The prepared electrolyte was injected into the vacant assemblies, and the inlets were closed. All the working areas were of 2.34 cm2 (1.3 cm \u00d7 1.8 cm). Finally, the filled assemblies were subjected to UV irradiation at a wavelength of 360 nm for periods of 0, 5, 10, and 20 min.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75719, "context": "EIS experiments. The electrolyte 65 mM Na[FeIII-racEDDHA], 0.7 M Na2SO4, 155 mM borate pH 9, was reduced at the negative electrode to reach 50% SoC (determined by photometry), using the same setup outlined in the charge\u2013discharge cycling experiments. Potassium ferro/ferricyanide at 50% SoC was directly prepared with 32.5 mM K3[FeIII(CN)6], 32.5 mM K4[FeII(CN)6], 0.7 M Na2SO4, 1 mM borate, pH 9. Three-electrode configuration with two CRLEs used as working and counter electrode and a reference electrode (Ag/AgCl 3 M KCl) were connected to a BioLogic VSP potentiostat. The impedance spectra were recorded from 3 \u00d7 104 Hz to 5 \u00d7 10\u22122 Hz. An AC amplitude of 100 mV was applied on top of a DC potential matching the open cell potential at 50% SoC. All electrodes used had a similar roving length (72 mm) and weight (0.23 g).", "question": "What's the electrolyte?", "answer": "65 mM Na[FeIII-racEDDHA], 0.7 M Na2SO4, 155 mM borate pH 9", "answer_start": 33}
{"document_id": 75724, "context": "While selecting the optimal potential range for oxocarbon derivatives, it is important to know that poorly reversible transformations can occur, especially at high potentials. For example, it is known that oxidation products of rhodizonates dissolve in the electrolytes, causing a rapid capacity decay. For this reason, only four-electron reduction is considered suitable for the practical operation of rhodizonates.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75734, "context": "To assemble the ssZIBs, the polymer electrolyte was synthesized via polymerization of PAM combined with CNFs. Specifically, 1.33 g of CNFs (1.5 wt% water suspension, University of Maine, Orono, ME, USA) were first dispersed in 20 mL of 1 M Zn(CF3SO3)2 solution with extensive high-speed stirring. After that, 50 mg of ammonium persulfate, 3 g of acrylamide (AM) monomers and 50 mg of N,N\u2032-methylenebisacrylamide (BIS) were added to the suspension. After being stirred at 25 \u00b0C for 2 h, the mixture was cast onto a glass Petri dish. Then, the formed membrane was put in an oven and heated at 60 \u00b0C for half an hour. During this heating treatment, acrylamide was grafted onto the CNF surface through free radical polymerization. Finally, after being cooled to room temperature, a crosslinked CNF\u2013PAM film was obtained. The prepared polymeric film shows high flexibility, and can be applied as a solid-state separator directly.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75739, "context": "Solid-state Zn\u2013air battery with a sandwich structure was assembled by replacing the zinc sheet and liquid electrolyte with a zinc foil (purity 99.9 wt%) and the as-fabricated PAM sheet, respectively.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75744, "context": "Among ceramic electrolytes, the garnet-structured oxide Li7La3Zr2O12 (LLZO) has attracted attention as a core material of next-generation batteries (post-LIBs) because it exhibits excellent chemical/electrochemical stability against Li metals and has large electrochemical stability window. In particular, LLZO offers significant advantages in inhibiting Li dendrite formation because it is a single-ion conductor (transference number \u223c1), has a high shear modulus (\u223c60 GPa) and stable interface with Li metals. Despite these intrinsic advantages, LLZO still has the problem of short circuit formation caused by Li propagation through LLZO particularly under high current densities. The penetration of Li through the polycrystalline LLZO electrolyte has been recently interpreted in terms of wettability of Li metals on LLZO, mechanical failure induced by stresses during Li plating that caused flaws on the LLZO surface, high electronic conductivity and a high interfacial resistance as well as non-uniform current distribution by lithium carbonate (Li2CO3) formed on the LLZO surface by the reaction between water vapor, carbon dioxide and LLZO in ambient air. Li propagation is known to occur via preferential plating at the grain boundaries (GBs), and the interface property of Li metal and LLZO plays a critical role in Li penetration when a high current density is applied to the interfaces. Because of the impurities or defects that predominantly exist on the GBs, different energy states for reduction at GBs might lead to non-uniform distribution of Li plating and preferential propagation of Li ions through the GBs. However, the mechanism of Li dendrite formation is unclear and remains controversial. Here, we investigated the mechanism of Li dendrite formation for the crystalline Ta-doped LLZO (Li6.5La3Zr1.5Ta0.5O12, LLZTO) by examining their energy band structures and defect states using various analytical techniques including reflection electron energy loss spectroscopy (REELS), scanning photoelectron microscopy (SPEM), and nanoscale charge-based deep level transient spectroscopy (Nano Q-DLTS). The measurement results revealed that the metallic Li plating along the GBs originates from the plentiful defect states in the GBs, implying that the formation of Li dendrites can be avoided if a thin layer with a wide bandgap is coated on LLZTO grains. Based on these analytical measurements, we adopted the laser annealing of LLZTO as a bandgap engineering method to suppress the Li dendrite formation by forming a surface structure of amorphous LLZTO and Li2O2 with wide bandgaps, which can block the electron injection into the grain boundaries. In addition, our electrochemical measurement results for the laser-treated LLZTO demonstrated that the stability and cycling performance were significantly improved. This study sheds light on the importance of electronic structure, in particular, defect states in developing ceramic solid electrolytes for Li metal batteries and the practicality of surface modification by laser treatment.", "question": "What's the electrolyte?", "answer": " Li7La3Zr2O12 (LLZO)", "answer_start": 55}
{"document_id": 75744, "context": "Among ceramic electrolytes, the garnet-structured oxide Li7La3Zr2O12 (LLZO) has attracted attention as a core material of next-generation batteries (post-LIBs) because it exhibits excellent chemical/electrochemical stability against Li metals and has large electrochemical stability window. In particular, LLZO offers significant advantages in inhibiting Li dendrite formation because it is a single-ion conductor (transference number \u223c1), has a high shear modulus (\u223c60 GPa) and stable interface with Li metals. Despite these intrinsic advantages, LLZO still has the problem of short circuit formation caused by Li propagation through LLZO particularly under high current densities. The penetration of Li through the polycrystalline LLZO electrolyte has been recently interpreted in terms of wettability of Li metals on LLZO, mechanical failure induced by stresses during Li plating that caused flaws on the LLZO surface, high electronic conductivity and a high interfacial resistance as well as non-uniform current distribution by lithium carbonate (Li2CO3) formed on the LLZO surface by the reaction between water vapor, carbon dioxide and LLZO in ambient air. Li propagation is known to occur via preferential plating at the grain boundaries (GBs), and the interface property of Li metal and LLZO plays a critical role in Li penetration when a high current density is applied to the interfaces. Because of the impurities or defects that predominantly exist on the GBs, different energy states for reduction at GBs might lead to non-uniform distribution of Li plating and preferential propagation of Li ions through the GBs. However, the mechanism of Li dendrite formation is unclear and remains controversial. Here, we investigated the mechanism of Li dendrite formation for the crystalline Ta-doped LLZO (Li6.5La3Zr1.5Ta0.5O12, LLZTO) by examining their energy band structures and defect states using various analytical techniques including reflection electron energy loss spectroscopy (REELS), scanning photoelectron microscopy (SPEM), and nanoscale charge-based deep level transient spectroscopy (Nano Q-DLTS). The measurement results revealed that the metallic Li plating along the GBs originates from the plentiful defect states in the GBs, implying that the formation of Li dendrites can be avoided if a thin layer with a wide bandgap is coated on LLZTO grains. Based on these analytical measurements, we adopted the laser annealing of LLZTO as a bandgap engineering method to suppress the Li dendrite formation by forming a surface structure of amorphous LLZTO and Li2O2 with wide bandgaps, which can block the electron injection into the grain boundaries. In addition, our electrochemical measurement results for the laser-treated LLZTO demonstrated that the stability and cycling performance were significantly improved. This study sheds light on the importance of electronic structure, in particular, defect states in developing ceramic solid electrolytes for Li metal batteries and the practicality of surface modification by laser treatment.", "question": "What's the electrolyte?", "answer": "LLZO", "answer_start": 733}
{"document_id": 75749, "context": "The as-prepared polymer SP, Super P carbon and poly(vinylidene fluoride) (PVDF) binder with a mass ratio of 6/3/1 were added to a flask, and then dispersed in 1-methyl-2-pyrrolidinone (NMP) after being vigorously stirred for 10 h. The obtained slurry was coated on Cu foil, followed by drying at 100 \u00b0C in vacuo. The Cu foil was punched with a diameter of 14 mm as the anode electrode and the mass of SP was about 1.8 mg. A CR2032 coin-type cell was assembled in a glove box with SP as the working electrode, Celgard2400 polypropylene as the separator, lithium foil as the counter and reference electrode, and the prepared electrolyte consisted of a mixture of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC) (DMC/EMC/EC = 5/2/3 v/v/v). The galvanostatic charge\u2013discharge (GCD) and rate properties were determined by using a LAND battery test system at room temperature. After being pre-cycled at 0.2 C (20 mA h g\u22121) for three cycles, the battery was then tested at 1 C (100 mA h g\u22121) for 200 cycles. The cyclic voltammograms (CV) ranging from 0.01 V to 3 V were recorded with a CHI600E electrochemical working station with a scan rate of 0.1 mV s\u22121.", "question": "What's the anode?", "answer": "Cu foil", "answer_start": 317}
{"document_id": 75749, "context": "The as-prepared polymer SP, Super P carbon and poly(vinylidene fluoride) (PVDF) binder with a mass ratio of 6/3/1 were added to a flask, and then dispersed in 1-methyl-2-pyrrolidinone (NMP) after being vigorously stirred for 10 h. The obtained slurry was coated on Cu foil, followed by drying at 100 \u00b0C in vacuo. The Cu foil was punched with a diameter of 14 mm as the anode electrode and the mass of SP was about 1.8 mg. A CR2032 coin-type cell was assembled in a glove box with SP as the working electrode, Celgard2400 polypropylene as the separator, lithium foil as the counter and reference electrode, and the prepared electrolyte consisted of a mixture of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC) (DMC/EMC/EC = 5/2/3 v/v/v). The galvanostatic charge\u2013discharge (GCD) and rate properties were determined by using a LAND battery test system at room temperature. After being pre-cycled at 0.2 C (20 mA h g\u22121) for three cycles, the battery was then tested at 1 C (100 mA h g\u22121) for 200 cycles. The cyclic voltammograms (CV) ranging from 0.01 V to 3 V were recorded with a CHI600E electrochemical working station with a scan rate of 0.1 mV s\u22121.", "question": "What's the electrolyte?", "answer": "a mixture of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC) (DMC/EMC/EC = 5/2/3 v/v/v)", "answer_start": 648}
{"document_id": 75725, "context": "The specific capacitances of the as-prepared ASSPs at different scan rates are presented in Fig. 3(d). The maximum specific capacitance of Bi/CNTs is 68.7 F cm\u22123 calculated from CV curves, which is larger than the values of the ASSPs based on 2D Bi (specific capacitance of 36.8 F cm\u22123) and CNTs (specific capacitance of 29.4 F cm\u22123). More importantly, the specific capacitance of the as-assembled Bi/CNT ASSP still maintains 33.0 F cm\u22123 with 48% capacitance retention when the scan rate is increased 20-fold from 5 to 100 mV s\u22121, superior to 43% capacitance retention of 2D Bi, demonstrating its good rate capability. The high specific capacitance and good rate capability of the as-prepared Bi/CNT SCs are mainly attributed to the excellent electronic conductivity of the exfoliated Bi NSs and CNTs, which can provide an effective charge transport pathway during the charge/discharge process. Meanwhile, the buckled layer structure of the Bi NSs offers abundant active sites with the full surface exposed and enable fast access of electrolyte ions.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75730, "context": "Electrospun nanomaterials are very promising electrode materials for SCs in terms of outstanding electronic conductivity and electrolyte accessibility, rich and uniform porosity, and excellent structural stability. In this review, we extensively discussed the recent advances in electrospun nanomaterial electrodes for SCs. Firstly, pore engineering (i.e. activation, blend polymer electrospinning, addition of metal salts, and template method) and heteroatom doping as two major approaches to improve the electrochemical performance of electrospun CNFs were reviewed. Furthermore, due to their superb mechanical strength, high electronic conductivity, good compatibility and lightweight characteristics, CNFs acting as the attractive host/substrate for diverse electroactive materials such as metal oxides, metal phosphides, and metal\u2013organic frameworks were summarized with critical insights. Finally, electrospun carbon-free materials represented by metal oxides in different compositions (spinel-type oxides, perovskites, metal oxide\u2013metal oxide composites, etc.) and architectures (porous, hollow, core\u2013shell, etc.) were also discussed. Despite increasingly successful examples demonstrating the great potential of electrospun nanomaterial electrodes, there are still challenges and opportunities in this field which have not been fully explored:", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75731, "context": "The photovoltaic performances of the crosslinked cells are higher than the non-crosslinked ones for both TiO2 and NiO based DSSCs, whatever the redox mediator used in the electrolyte. For TiO2 based DSSCs, this mostly results from a larger short circuit photocurrent density (Jsc) with the crosslinked dyes. On the other hand, the crosslinked NiO based p-DSSCs display much higher Voc with both redox mediators. However, on NiO based p-DSSCs the iodine based electrolyte gives lower Jsc after crosslinking. Jsc is controlled by the light harvesting efficiency (LHE), the charge injection quantum yield, the charge recombination reactions and by the charge collection efficiency. LHE is certainly not the cause of the lower Jsc, because the absorbance has not changed after crosslinking. Likewise, the hole injection efficiency is most certainly not affected by the crosslinking, because the current density is not diminished after crosslinking with the cobalt electrolyte. If an enhancement of the charge recombination reactions was the cause of the lower Jsc, first the Voc would be decreased as well, which is the reverse and second it would occur with the cobalt electrolyte, which is not the case either. Logically, we can therefore interpret the lower Jsc as a consequence of the lower efficiency of the dye regeneration step, which directly reduces the charge collection efficiency. It was previously reported by Xu and co-workers, that electron deficient triazoles similar to those involved in this study can make anion\u2013\u03c0 interaction with iodide. This hypothesis is supported by observing that the 1H NMR chemical shift of triazole of the reference compound benzyl-1,2,3-triazole-4-carboxylic acid methyl ester 15 was down-field shifted upon addition of Bu4NI in the NMR tube (Fig. S24\u2020). As a result, after crosslinking the concentration of iodide is certainly raised in the vicinity of the DPP 2 and might therefore hinder the approach of triiodide and consequently limit the charge regeneration efficiency of the reduced DPP after hole injection. In both devices, the increase of the Voc after crosslinking is most probably due to lower interfacial charge recombination coming from lower access of the redox mediator to the surface semiconductor. Indeed, inspection of the current/voltage characteristics of the solar cell recorded in the dark demonstrate that current of the crosslinked solar cells is significantly lower than the non-crosslinked ones (Fig. S20\u2013S23\u2020). Interfacial charge recombination between the redox mediator and the hole in NiO is known to be a major source of energy loss in p-DSSCs, therefore it is not unexpected that the reduction of this process impacts more importantly NiO based solar cells than TiO2 DSSCs.", "question": "What's the electrolyte?", "answer": "iodine ", "answer_start": 446}
{"document_id": 75737, "context": "The study of the voltage traces follows the methodology introduced in previous studies, to observe the characteristic peaking behaviour that originates from pitting of the stripping electrode. Previous reports have assigned the typical voltage profile to specific deposition and pitting processes: when plating Li, there is initially a large overpotential associated with the nucleation of Li deposits, which then decreases rapidly towards a local minimum due to an increased surface area for deposition. When switching polarity after the first deposition, the microstructures formed previously in the first half cycle are oxidised and removed from the stripping electrode. When all of the microstructures have been dissolved completely (or been detached from the electrode surface forming \u2018dead Li\u2019) the overpotential increases rapidly. A peak is seen as the overpotential drops again, labelled \u201cpitting\u201d in Fig. 4a, as this behaviour has been assigned to the onset of bulk metal dissolution or pitting of the Li metal surface and an increase in surface area. When comparing different electrolytes, a more pronounced peaking behaviour has been associated with substantial impedance differences and spatial variations in the SEI layers that lead to non-uniform stripping and the formation of dead Li.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75741, "context": "In addition to such capabilities, integration of CMOS fabrication with silicon micromachining allowed for the incorporation of on-chip circuitry, such as signal amplifiers, multiplexers to reduce output channel count, or application-specific integrated circuits (ASIC). Furthermore, the monolithic integration of on-chip circuitry and electrodes reduced the parasitic capacitance between the circuits. Silicon dioxide films were often used to cover electrodes to reduce artifacts induced at the electrode\u2013electrolyte interface.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75733, "context": "In order to enhance the capacity and rate performance of the electrodes, Fan et al. used 2,6-AQDS 1b in combination with carbon nanotubes (CNTs) and a DME-based electrolyte. Reversible Qm was up to 174 mA h g\u22121, higher than the theoretical value. It was partially attributed to the contribution from CNTs (23 mA h g\u22121). The authors assembled a full cell, which had pre-potassiated graphite as an anode. The cell had a Qm of up to 87 mA h g\u22121 (per mass of AQDS) with an average discharge voltage of 1.1 V. At 500 mA g\u22121, the capacity retention of the full cell was 33% after 2500 cycles.", "question": "What's the anode?", "answer": "graphite", "answer_start": 381}
{"document_id": 75733, "context": "In order to enhance the capacity and rate performance of the electrodes, Fan et al. used 2,6-AQDS 1b in combination with carbon nanotubes (CNTs) and a DME-based electrolyte. Reversible Qm was up to 174 mA h g\u22121, higher than the theoretical value. It was partially attributed to the contribution from CNTs (23 mA h g\u22121). The authors assembled a full cell, which had pre-potassiated graphite as an anode. The cell had a Qm of up to 87 mA h g\u22121 (per mass of AQDS) with an average discharge voltage of 1.1 V. At 500 mA g\u22121, the capacity retention of the full cell was 33% after 2500 cycles.", "question": "What's the electrolyte?", "answer": " DME-based", "answer_start": 150}
{"document_id": 75755, "context": "The preparation of N-doped carbon nanofibers decorated with Mo2C quantum dots (Mo2C@NCF) is illustrated in Scheme 1. Mo2C@NCF was first fabricated via an electrospinning technology followed by a high-temperature annealing process. Afterwards, facile glow discharge plasma (GPD) was employed on the surface of Mo2C@NCF. Fig. 1a shows the XRD patterns of as-prepared Mo2C@NCF and GDP-Mo2C@NCF. The diffraction peaks of both Mo2C@NC and GDP-Mo2C@NC are in good agreement with that of hexagonal Mo2C (JCPDS 35-0787) without any impurity peaks, suggesting the high purity of Mo2C. After high energy glow plasma treatment, all the characteristic peaks become stronger. As shown in the SEM and TEM images (Fig. 1b and c), Mo2C@NCF displays a fibrillar structure with a smooth surface and an average diameter of \u223c100 nm, and the one-dimensional orientation benefits fast transport of electrons/ions. The HRTEM images show the distribution of Mo2C quantum dots with an average diameter of 3\u20134 nm encapsulated in the carbon fiber though there are no lattice fringes (Fig. 1d and e). Different from that of Mo2C@NCF, the surface of GDP-Mo2C@NCF is etched using the high energy particles during the plasma process, leading to a rough appearance and exposure of Mo2C quantum dots (Fig. 1f and g). This morphological change offers a large electrode\u2013electrolyte contact area to ensure high availability of catalytically active sites. The HRTEM images clearly demonstrate the presence of Mo2C quantum dots, and an observed lattice fringe spacing of 0.24 nm corresponding to the (101) plane of Mo2C (Fig. 1h and i). The EDX mapping images confirm the uniform distribution of C, N and Mo elements on the carbon fiber (Fig. 1j).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75756, "context": "Herein, a Li/LiV2(PO4)3 primary battery (Fig. 1a) with a long shelf life is proposed, which exhibits impressive electrochemical performances under high power densities and low-temperature conditions. It has been found that the corrosion of the Al current collector triggered by the organic radical cations generated from the electrochemical oxidation of EC at high potentials; and the detrimental reaction between LiV2(PO4)3 and electrolyte lead to the self-discharge of Li/LiV2(PO4)3 primary batteries. When EC was replaced by PC, the corrosion of the Al foil was alleviated. LiBOB was found to be conducive to increase the shelf life of the Li/LiV2(PO4)3 primary batteries as it formed a protective film on the surface of the cathode, which effectively alleviated the side reaction between LiV2(PO4)3 and the electrolyte. Most importantly, the Li/LiV2(PO4)3 primary batteries exhibited excellent performances at high charge/discharge rates (up to 50C) and even at temperatures as low as \u221240 \u00b0C.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75756, "context": "Herein, a Li/LiV2(PO4)3 primary battery (Fig. 1a) with a long shelf life is proposed, which exhibits impressive electrochemical performances under high power densities and low-temperature conditions. It has been found that the corrosion of the Al current collector triggered by the organic radical cations generated from the electrochemical oxidation of EC at high potentials; and the detrimental reaction between LiV2(PO4)3 and electrolyte lead to the self-discharge of Li/LiV2(PO4)3 primary batteries. When EC was replaced by PC, the corrosion of the Al foil was alleviated. LiBOB was found to be conducive to increase the shelf life of the Li/LiV2(PO4)3 primary batteries as it formed a protective film on the surface of the cathode, which effectively alleviated the side reaction between LiV2(PO4)3 and the electrolyte. Most importantly, the Li/LiV2(PO4)3 primary batteries exhibited excellent performances at high charge/discharge rates (up to 50C) and even at temperatures as low as \u221240 \u00b0C.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75771, "context": "To compare different time scales, both relatively long and short pulse lengths were initially chosen, with TON = TOFF of either 1 s or 5 ms. The electrochemistry for pulse plating at 1 mA cm\u22122 and TON, TOFF = 1 s in LP30 electrolyte is shown in Fig. 5 (see Fig. S26 and S27\u2020 for additional pulse plating data for other electrolyte formulations); this corresponds to a duty cycle of \u03b8duty = TON/(TON + TOFF) = 0.5 and an average current density of 0.5 mA cm\u22122. Thus, the data can be readily compared to the constant current experiments at 0.5 mA cm\u22122.", "question": "What's the electrolyte?", "answer": "LP30 ", "answer_start": 216}
{"document_id": 75757, "context": "Fig. 2a shows the 7Li in situ NMR spectra continuously acquired during a 0.5 mA cm\u22122 constant current experiment. The resonance from Li metal depends on the orientation of the Li metal anode strip with respect to the static magnetic field, B0, due to Li metal's temperature independent paramagnetism (TIP). Aligning the cell perpendicular to the B0 field results in a 7Li resonance at around 245 ppm for the pristine Li metal (Fig. 2a) and all in situ cells presented in this work were aligned in this fashion. When depositing Li in both LP30 and LP30 + FEC, a new peak around 260 ppm emerges that continues to grow as a current of 0.5 mA cm\u22122 is passed (Fig. 2a). This new resonance is indicative of mossy structures growing near to the Li metal surface. Whisker-like morphologies are observed in the SEM micrographs as the major morphology after plating for 3.5 mA h cm\u22122 in LP30 electrolyte, whereas dense, thick buds (diameter of surface features \u223c5\u201310 \u03bcm) are observed for LP30 + FEC (Fig. 2b).", "question": "What's the electrolyte?", "answer": "LP30", "answer_start": 877}
{"document_id": 75767, "context": "The electrocatalytic application of HEA NPs in the selective CO2 reduction reaction (CO2RR) has also been reported recently. For example, Nellaiappan et al. reported quinary fcc-AuPtAgPdCu NPs as an efficient CO2RR electrocatalyst toward CH4 and C2H4 in the low overpotential region. The five elements in the quinary HEA NPs were homogeneously distributed, whose chemical environments adopt metallic characteristics determined by XPS analysis except for Cu; a small amount of Cu2+ content was observed. The quinary fcc-AuPtAgPdCu NPs obtained superior selectivity toward the CO2RR in the low overpotential region, that is, FEmethane = 38.2% and FEethylene = 29.5% at \u22120.9 VAg/AgCl (\u22120.3 VRHE) in a CO2-saturated 0.5 M K2SO4 electrolyte (FE: faradaic efficiency). Based on their DFT calculation, the excellent electrocatalytic activity toward the CO2RR has mainly originated from redox-active Cu content in AuPtAgPdCu, while other elements provide an additional synergy in the CO2RR. Also, the long-term stability of the catalyst was verified by a chronoamperometry test for 5 h in a CO2-saturated 0.5 M K2SO4 electrolyte.", "question": "What's the electrolyte?", "answer": "0.5 M K2SO4", "answer_start": 712}
{"document_id": 75767, "context": "The electrocatalytic application of HEA NPs in the selective CO2 reduction reaction (CO2RR) has also been reported recently. For example, Nellaiappan et al. reported quinary fcc-AuPtAgPdCu NPs as an efficient CO2RR electrocatalyst toward CH4 and C2H4 in the low overpotential region. The five elements in the quinary HEA NPs were homogeneously distributed, whose chemical environments adopt metallic characteristics determined by XPS analysis except for Cu; a small amount of Cu2+ content was observed. The quinary fcc-AuPtAgPdCu NPs obtained superior selectivity toward the CO2RR in the low overpotential region, that is, FEmethane = 38.2% and FEethylene = 29.5% at \u22120.9 VAg/AgCl (\u22120.3 VRHE) in a CO2-saturated 0.5 M K2SO4 electrolyte (FE: faradaic efficiency). Based on their DFT calculation, the excellent electrocatalytic activity toward the CO2RR has mainly originated from redox-active Cu content in AuPtAgPdCu, while other elements provide an additional synergy in the CO2RR. Also, the long-term stability of the catalyst was verified by a chronoamperometry test for 5 h in a CO2-saturated 0.5 M K2SO4 electrolyte.", "question": "What's the electrolyte?", "answer": "CO2-saturated 0.5 M K2SO4", "answer_start": 1083}
{"document_id": 75758, "context": "The concentration of 7Li electrolyte as a function of time is, ce7(t) = [Li+]fe7(t) with the initial condition for the fraction of 7Li in the electrolyte, fe7(0) = 0.92 (the natural abundance of 7Li). Since the diffusion coefficient in lithium metal, Dm, is more than four orders of magnitude smaller than the diffusion Li+ coefficient in the electrolyte (Table 1), the diffusion of Li+ throughout the electrolyte is considered instantaneous.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75769, "context": "The Li3V2(PO4)3 (LVP) electrode slurry was prepared by mixing LVP, carbon black (Super P), and polyvinylidene fluoride (PVDF) in a weight ratio of 8:1:1 in N-methyl pyrrolidone (NMP); this slurry was coated on the Al foil followed by drying at 120 \u00b0C for 24 h. Then, the electrodes were cut into disks with a diameter of 14.0 mm and used for coin cell assembly. The mass loading of the LVP electrodes was 2.3\u20132.6 mg cm\u22122. The primary batteries (CR2016, coin-type cell) were assembled using the Li3V2(PO4)3 cathode, Celgard 2325 separator, electrolytes, and Li metal anode in an argon-filled glove box.", "question": "What's the cathode?", "answer": "Li3V2(PO4)3", "answer_start": 494}
{"document_id": 75769, "context": "The Li3V2(PO4)3 (LVP) electrode slurry was prepared by mixing LVP, carbon black (Super P), and polyvinylidene fluoride (PVDF) in a weight ratio of 8:1:1 in N-methyl pyrrolidone (NMP); this slurry was coated on the Al foil followed by drying at 120 \u00b0C for 24 h. Then, the electrodes were cut into disks with a diameter of 14.0 mm and used for coin cell assembly. The mass loading of the LVP electrodes was 2.3\u20132.6 mg cm\u22122. The primary batteries (CR2016, coin-type cell) were assembled using the Li3V2(PO4)3 cathode, Celgard 2325 separator, electrolytes, and Li metal anode in an argon-filled glove box.", "question": "What's the anode?", "answer": " Li metal", "answer_start": 556}
{"document_id": 75769, "context": "The Li3V2(PO4)3 (LVP) electrode slurry was prepared by mixing LVP, carbon black (Super P), and polyvinylidene fluoride (PVDF) in a weight ratio of 8:1:1 in N-methyl pyrrolidone (NMP); this slurry was coated on the Al foil followed by drying at 120 \u00b0C for 24 h. Then, the electrodes were cut into disks with a diameter of 14.0 mm and used for coin cell assembly. The mass loading of the LVP electrodes was 2.3\u20132.6 mg cm\u22122. The primary batteries (CR2016, coin-type cell) were assembled using the Li3V2(PO4)3 cathode, Celgard 2325 separator, electrolytes, and Li metal anode in an argon-filled glove box.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75779, "context": "Fig. 4c shows the electrochemical impendence spectra of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling, after the first cycle and after 100 cycles. The Rs value of the battery in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, connected to the intercept on the real impedance axis at a high frequency in the EIS spectra, is relatively small and equal for the pristine state and after cycling, which suggests good ion diffusion in the electrolyte and good stability of the electrode materials before and after cycling. The Rct value represented the charge transfer resistance increase after the first cycle and after 100 cycles, indicating that a passivation layer may be formed on the NTP anode, which could be a significant factor in the improvement of the cycling performance of the NVP/NTP full cell. Moreover, the XRD patterns (Fig. S16\u2020) and SEM images (Fig. S17\u2020) of NVP/C and NTP/C before and after 500 cycles were recorded, respectively. The results indicate that the Na\u2013H2O\u2013urea\u2013DMF electrolyte is conducive to achieving excellent stability of the NVP cathode. In addition, a NiHCF//NTP full cell displays 80% capacity retention after 2000 cycles at 2C rate (Fig. 4d).", "question": "What's the cathode?", "answer": "NVP ", "answer_start": 1059}
{"document_id": 75779, "context": "Fig. 4c shows the electrochemical impendence spectra of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling, after the first cycle and after 100 cycles. The Rs value of the battery in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, connected to the intercept on the real impedance axis at a high frequency in the EIS spectra, is relatively small and equal for the pristine state and after cycling, which suggests good ion diffusion in the electrolyte and good stability of the electrode materials before and after cycling. The Rct value represented the charge transfer resistance increase after the first cycle and after 100 cycles, indicating that a passivation layer may be formed on the NTP anode, which could be a significant factor in the improvement of the cycling performance of the NVP/NTP full cell. Moreover, the XRD patterns (Fig. S16\u2020) and SEM images (Fig. S17\u2020) of NVP/C and NTP/C before and after 500 cycles were recorded, respectively. The results indicate that the Na\u2013H2O\u2013urea\u2013DMF electrolyte is conducive to achieving excellent stability of the NVP cathode. In addition, a NiHCF//NTP full cell displays 80% capacity retention after 2000 cycles at 2C rate (Fig. 4d).", "question": "What's the anode?", "answer": "NTP ", "answer_start": 687}
{"document_id": 75779, "context": "Fig. 4c shows the electrochemical impendence spectra of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling, after the first cycle and after 100 cycles. The Rs value of the battery in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, connected to the intercept on the real impedance axis at a high frequency in the EIS spectra, is relatively small and equal for the pristine state and after cycling, which suggests good ion diffusion in the electrolyte and good stability of the electrode materials before and after cycling. The Rct value represented the charge transfer resistance increase after the first cycle and after 100 cycles, indicating that a passivation layer may be formed on the NTP anode, which could be a significant factor in the improvement of the cycling performance of the NVP/NTP full cell. Moreover, the XRD patterns (Fig. S16\u2020) and SEM images (Fig. S17\u2020) of NVP/C and NTP/C before and after 500 cycles were recorded, respectively. The results indicate that the Na\u2013H2O\u2013urea\u2013DMF electrolyte is conducive to achieving excellent stability of the NVP cathode. In addition, a NiHCF//NTP full cell displays 80% capacity retention after 2000 cycles at 2C rate (Fig. 4d).", "question": "What's the electrolyte?", "answer": "Na\u2013H2O\u2013urea\u2013DMF", "answer_start": 77}
{"document_id": 75779, "context": "Fig. 4c shows the electrochemical impendence spectra of the full cell in the Na\u2013H2O\u2013urea\u2013DMF electrolyte before cycling, after the first cycle and after 100 cycles. The Rs value of the battery in the Na\u2013H2O\u2013urea\u2013DMF electrolyte, connected to the intercept on the real impedance axis at a high frequency in the EIS spectra, is relatively small and equal for the pristine state and after cycling, which suggests good ion diffusion in the electrolyte and good stability of the electrode materials before and after cycling. The Rct value represented the charge transfer resistance increase after the first cycle and after 100 cycles, indicating that a passivation layer may be formed on the NTP anode, which could be a significant factor in the improvement of the cycling performance of the NVP/NTP full cell. Moreover, the XRD patterns (Fig. S16\u2020) and SEM images (Fig. S17\u2020) of NVP/C and NTP/C before and after 500 cycles were recorded, respectively. The results indicate that the Na\u2013H2O\u2013urea\u2013DMF electrolyte is conducive to achieving excellent stability of the NVP cathode. In addition, a NiHCF//NTP full cell displays 80% capacity retention after 2000 cycles at 2C rate (Fig. 4d).", "question": "What's the electrolyte?", "answer": "Na\u2013H2O\u2013urea\u2013DMF", "answer_start": 200}
{"document_id": 75765, "context": "Herein, we report a new finding that 3Mg/Mg2Sn alloy can be a promising solution to the aforementioned issues in Sn-based alloy-type MIB anodes. It is shown that 3Mg/Mg2Sn, which is composed of ternary phases (crystalline Mg-rich (c-Mg), amorphous Mg-rich (a-Mg), and intermetallic Mg2Sn phases), reversibly magnesiates/de-magnesiates a significant amount of Mg2+ ions in a non-Grignard and Lewis acid-free electrolyte even under high rates of C/D. In Table 1, the unprecedented electrochemical performance of 3Mg/Mg2Sn is compared with that of other popular alloy-type anodes. The origin of high capacities and excellent rate-capabilities is also discussed in the context of structural features. Finally, we describe the compatibility of 3Mg/Mg2Sn with versatile conventional electrolytes and the optimality of using 3Mg/Mg2Sn with Mg2+-trapping cathodes (e.g., Mo6S8).", "question": "What's the cathode?", "answer": "Mo6S8", "answer_start": 863}
{"document_id": 75765, "context": "Herein, we report a new finding that 3Mg/Mg2Sn alloy can be a promising solution to the aforementioned issues in Sn-based alloy-type MIB anodes. It is shown that 3Mg/Mg2Sn, which is composed of ternary phases (crystalline Mg-rich (c-Mg), amorphous Mg-rich (a-Mg), and intermetallic Mg2Sn phases), reversibly magnesiates/de-magnesiates a significant amount of Mg2+ ions in a non-Grignard and Lewis acid-free electrolyte even under high rates of C/D. In Table 1, the unprecedented electrochemical performance of 3Mg/Mg2Sn is compared with that of other popular alloy-type anodes. The origin of high capacities and excellent rate-capabilities is also discussed in the context of structural features. Finally, we describe the compatibility of 3Mg/Mg2Sn with versatile conventional electrolytes and the optimality of using 3Mg/Mg2Sn with Mg2+-trapping cathodes (e.g., Mo6S8).", "question": "What's the anode?", "answer": "Sn-based alloy-type MIB", "answer_start": 113}
{"document_id": 75765, "context": "Herein, we report a new finding that 3Mg/Mg2Sn alloy can be a promising solution to the aforementioned issues in Sn-based alloy-type MIB anodes. It is shown that 3Mg/Mg2Sn, which is composed of ternary phases (crystalline Mg-rich (c-Mg), amorphous Mg-rich (a-Mg), and intermetallic Mg2Sn phases), reversibly magnesiates/de-magnesiates a significant amount of Mg2+ ions in a non-Grignard and Lewis acid-free electrolyte even under high rates of C/D. In Table 1, the unprecedented electrochemical performance of 3Mg/Mg2Sn is compared with that of other popular alloy-type anodes. The origin of high capacities and excellent rate-capabilities is also discussed in the context of structural features. Finally, we describe the compatibility of 3Mg/Mg2Sn with versatile conventional electrolytes and the optimality of using 3Mg/Mg2Sn with Mg2+-trapping cathodes (e.g., Mo6S8).", "question": "What's the electrolyte?", "answer": "non-Grignard and Lewis acid-free", "answer_start": 374}
{"document_id": 75765, "context": "Herein, we report a new finding that 3Mg/Mg2Sn alloy can be a promising solution to the aforementioned issues in Sn-based alloy-type MIB anodes. It is shown that 3Mg/Mg2Sn, which is composed of ternary phases (crystalline Mg-rich (c-Mg), amorphous Mg-rich (a-Mg), and intermetallic Mg2Sn phases), reversibly magnesiates/de-magnesiates a significant amount of Mg2+ ions in a non-Grignard and Lewis acid-free electrolyte even under high rates of C/D. In Table 1, the unprecedented electrochemical performance of 3Mg/Mg2Sn is compared with that of other popular alloy-type anodes. The origin of high capacities and excellent rate-capabilities is also discussed in the context of structural features. Finally, we describe the compatibility of 3Mg/Mg2Sn with versatile conventional electrolytes and the optimality of using 3Mg/Mg2Sn with Mg2+-trapping cathodes (e.g., Mo6S8).", "question": "What's the anode?", "answer": " alloy-type", "answer_start": 558}
{"document_id": 75770, "context": "To elucidate the practical applicability, HSABs were assembled using metallic Na as the anode immersed in 1 M NaClO4 in TEGDME organic electrolyte, NASICON solid electrolyte as the separator, O2-saturated 0.1 M NaOH aqueous as the aqueous electrolyte, Pt3Ni1/NixFe LDHs, 20% Pt/C, and RuO2 loaded on Ni foam as the cathode (Fig. 1a). During the discharge process, the Na metal on the anode side is oxidized to Na+ and moves into the NaOH aqueous through the NASICON separator, and the ORR simultaneously occurs at the cathode. On charging, the Na+ ions were transported from the aqueous electrolyte into the anode chamber and reduced to metallic Na, together with the concurrent OER at the cathode side.", "question": "What's the cathode?", "answer": "RuO2 loaded on Ni foam", "answer_start": 285}
{"document_id": 75770, "context": "To elucidate the practical applicability, HSABs were assembled using metallic Na as the anode immersed in 1 M NaClO4 in TEGDME organic electrolyte, NASICON solid electrolyte as the separator, O2-saturated 0.1 M NaOH aqueous as the aqueous electrolyte, Pt3Ni1/NixFe LDHs, 20% Pt/C, and RuO2 loaded on Ni foam as the cathode (Fig. 1a). During the discharge process, the Na metal on the anode side is oxidized to Na+ and moves into the NaOH aqueous through the NASICON separator, and the ORR simultaneously occurs at the cathode. On charging, the Na+ ions were transported from the aqueous electrolyte into the anode chamber and reduced to metallic Na, together with the concurrent OER at the cathode side.", "question": "What's the anode?", "answer": "Na ", "answer_start": 78}
{"document_id": 75770, "context": "To elucidate the practical applicability, HSABs were assembled using metallic Na as the anode immersed in 1 M NaClO4 in TEGDME organic electrolyte, NASICON solid electrolyte as the separator, O2-saturated 0.1 M NaOH aqueous as the aqueous electrolyte, Pt3Ni1/NixFe LDHs, 20% Pt/C, and RuO2 loaded on Ni foam as the cathode (Fig. 1a). During the discharge process, the Na metal on the anode side is oxidized to Na+ and moves into the NaOH aqueous through the NASICON separator, and the ORR simultaneously occurs at the cathode. On charging, the Na+ ions were transported from the aqueous electrolyte into the anode chamber and reduced to metallic Na, together with the concurrent OER at the cathode side.", "question": "What's the electrolyte?", "answer": "1 M NaClO4 in TEGDME organic electrolyte", "answer_start": 106}
{"document_id": 75770, "context": "To elucidate the practical applicability, HSABs were assembled using metallic Na as the anode immersed in 1 M NaClO4 in TEGDME organic electrolyte, NASICON solid electrolyte as the separator, O2-saturated 0.1 M NaOH aqueous as the aqueous electrolyte, Pt3Ni1/NixFe LDHs, 20% Pt/C, and RuO2 loaded on Ni foam as the cathode (Fig. 1a). During the discharge process, the Na metal on the anode side is oxidized to Na+ and moves into the NaOH aqueous through the NASICON separator, and the ORR simultaneously occurs at the cathode. On charging, the Na+ ions were transported from the aqueous electrolyte into the anode chamber and reduced to metallic Na, together with the concurrent OER at the cathode side.", "question": "What's the anode?", "answer": "Na metal", "answer_start": 368}
{"document_id": 75770, "context": "To elucidate the practical applicability, HSABs were assembled using metallic Na as the anode immersed in 1 M NaClO4 in TEGDME organic electrolyte, NASICON solid electrolyte as the separator, O2-saturated 0.1 M NaOH aqueous as the aqueous electrolyte, Pt3Ni1/NixFe LDHs, 20% Pt/C, and RuO2 loaded on Ni foam as the cathode (Fig. 1a). During the discharge process, the Na metal on the anode side is oxidized to Na+ and moves into the NaOH aqueous through the NASICON separator, and the ORR simultaneously occurs at the cathode. On charging, the Na+ ions were transported from the aqueous electrolyte into the anode chamber and reduced to metallic Na, together with the concurrent OER at the cathode side.", "question": "What's the electrolyte?", "answer": "NASICON solid electrolyte", "answer_start": 148}
{"document_id": 75780, "context": "In the current study, we investigate composite cathodes that combine a NMC cathode (LiNi0.5Mn0.3Co0.2O2) with amorphous 75Li2S\u201325P2S5 (LPS) solid electrolyte. The cathode material was coated with an amorphous Li\u2013Zr-oxide (LZO) layer to reduce the reaction between NMC and LPS and to minimize the effect of the chemical instability on the electrochemical performance. SSB cells were constructed with In metal as the anode, a composite of NMC/LPS/carbon nanofiber (CNF) in a weight ratio of 60:35:5 as the cathode, and LPS as the solid electrolyte. All the cells were cycled between 1.4 and 3.7 V vs. In (between 2 and 4.3 V vs. Li/Li+) using constant-current constant-voltage (CCCV) charging and constant-current discharging at a rate of 0.05 mA cm\u22122. The details of the cell fabrication have been previously reported and are provided in the ESI.\u2020", "question": "What's the cathode?", "answer": "NMC ", "answer_start": 71}
{"document_id": 75780, "context": "In the current study, we investigate composite cathodes that combine a NMC cathode (LiNi0.5Mn0.3Co0.2O2) with amorphous 75Li2S\u201325P2S5 (LPS) solid electrolyte. The cathode material was coated with an amorphous Li\u2013Zr-oxide (LZO) layer to reduce the reaction between NMC and LPS and to minimize the effect of the chemical instability on the electrochemical performance. SSB cells were constructed with In metal as the anode, a composite of NMC/LPS/carbon nanofiber (CNF) in a weight ratio of 60:35:5 as the cathode, and LPS as the solid electrolyte. All the cells were cycled between 1.4 and 3.7 V vs. In (between 2 and 4.3 V vs. Li/Li+) using constant-current constant-voltage (CCCV) charging and constant-current discharging at a rate of 0.05 mA cm\u22122. The details of the cell fabrication have been previously reported and are provided in the ESI.\u2020", "question": "What's the anode?", "answer": "In metal", "answer_start": 399}
{"document_id": 75780, "context": "In the current study, we investigate composite cathodes that combine a NMC cathode (LiNi0.5Mn0.3Co0.2O2) with amorphous 75Li2S\u201325P2S5 (LPS) solid electrolyte. The cathode material was coated with an amorphous Li\u2013Zr-oxide (LZO) layer to reduce the reaction between NMC and LPS and to minimize the effect of the chemical instability on the electrochemical performance. SSB cells were constructed with In metal as the anode, a composite of NMC/LPS/carbon nanofiber (CNF) in a weight ratio of 60:35:5 as the cathode, and LPS as the solid electrolyte. All the cells were cycled between 1.4 and 3.7 V vs. In (between 2 and 4.3 V vs. Li/Li+) using constant-current constant-voltage (CCCV) charging and constant-current discharging at a rate of 0.05 mA cm\u22122. The details of the cell fabrication have been previously reported and are provided in the ESI.\u2020", "question": "What's the electrolyte?", "answer": "75Li2S\u201325P2S5 (LPS)", "answer_start": 120}
{"document_id": 75780, "context": "In the current study, we investigate composite cathodes that combine a NMC cathode (LiNi0.5Mn0.3Co0.2O2) with amorphous 75Li2S\u201325P2S5 (LPS) solid electrolyte. The cathode material was coated with an amorphous Li\u2013Zr-oxide (LZO) layer to reduce the reaction between NMC and LPS and to minimize the effect of the chemical instability on the electrochemical performance. SSB cells were constructed with In metal as the anode, a composite of NMC/LPS/carbon nanofiber (CNF) in a weight ratio of 60:35:5 as the cathode, and LPS as the solid electrolyte. All the cells were cycled between 1.4 and 3.7 V vs. In (between 2 and 4.3 V vs. Li/Li+) using constant-current constant-voltage (CCCV) charging and constant-current discharging at a rate of 0.05 mA cm\u22122. The details of the cell fabrication have been previously reported and are provided in the ESI.\u2020", "question": "What's the cathode?", "answer": "LiNi0.5Mn0.3Co0.2O2", "answer_start": 84}
{"document_id": 75768, "context": "The fast advancement in portable and wearable electronics has aroused growing demand for energy storage devices not only with high electrochemical performance but also having extra appealing characteristics, such as high safety, low cost, environmental friendliness, and so on. Supercapacitors are a kind of energy storage device demonstrating distinct advantages of simplicity in fabrication and high power density. However, the insufficient energy density has indeed hampered their application. In contrast, lithium-ion batteries possess a much higher energy density, but suffer considerably from cost and safety issues especially under some extreme conditions. Recently, rechargeable Zn\u2013MnO2 batteries have attracted significant research interest due to their unique features, including high safety, light weight, nontoxicity and ease of fabrication. Solid-state rechargeable Zn\u2013MnO2 batteries coupled with hydrogel electrolytes show excellent cycling stability, making them a promising alternative to lithium-ion batteries. Nevertheless, most electrodes for rechargeable Zn\u2013MnO2 batteries are made from synthetic and expensive materials like graphene, carbon nanotubes, acetylene black, etc., which encounter obstacles, such as complex synthesis process, low yield, insufficient capacity, and environmental incompatibility. It is also important to note that most of the recent studies on rechargeable Zn\u2013MnO2 batteries were focused on the optimization of electrochemically active substances, but ignored the structural design of the bulk electrode materials. As is well recognized, the hierarchical microstructure of electrodes may affect their electrochemical properties profoundly, in particular when the electrode is thick or the load of active substances is high.", "question": "What's the electrolyte?", "answer": "hydrogel", "answer_start": 910}
{"document_id": 75773, "context": "OECT device fabrication. OECT devices were oxygen plasma ashed before spin-coating the polymer solutions at 1000 rpm for 60 s. This was followed by baking the devices at 60 \u00b0C for 60 s before removing the sacrificial parylene layer. Following the parylene peel-off the devices were further baked at 140 \u00b0C for 30 min. A polydimethylsiloxane (PDMS) well was fabricated using Sylgard-184 base and a curing agent in a 10:1 ratio. The PDMS well contained the electrolyte with a total volume of 300 \u03bcl. TBA PF6 electrolytes and TBA PF6:DBSA mixed electrolytes (in both ACN and DCM) had a concentration of 0.1 M. The ratio of TBA PF6:DBSA was kept constant at 1:1 for all mixed electrolyte measurements.", "question": "What's the electrolyte?", "answer": "TBA PF6 electrolytes and TBA PF6:DBSA mixed electrolytes", "answer_start": 498}
{"document_id": 75787, "context": "As the initial SEI formed on copper modifies the nucleation and growth of lithium metal in a way that gives rise to a columnar microstructure, understanding the formation of this layer and its resulting properties is imperative. XPS results show that the initial SEI formed by galvanostatically bringing copper working electrodes to 0 V vs. Li/Li+ at 0.5 mA cm\u22122 in LP30 electrolyte with and without added HF are quite similar in chemical composition (Table S1\u2020). Both SEIs contain primarily LiF, LiOH, and organic species (Fig. 4), indicating that the nanostructure of this layer rather than its chemistry is likely key to modifying lithium nucleation and growth. The thickness of this initial SEI layer is roughly 2\u20133 nm based both on the charge passed (\u223c3 nm, assuming fully dense and uniform LiF (Fig. 3a)) and the Ar ion sputter rate (\u223c2 nm, calibrated using SiO2, Fig. S3\u2020). The presence of a smaller peak around 687.6 eV in the F1s spectrum for the as-received sample in Fig. 4a corresponds to PF6\u2212 and could be due to a more porous SEI that traps electrolyte. This is another indication of different SEI structures with and without an HF additive. Alternatively, this could be residue from incomplete electrolyte removal during rinsing.", "question": "What's the electrolyte?", "answer": "LP30 ", "answer_start": 366}
{"document_id": 75791, "context": "The NASICON solid electrolyte material characterization was performed through an XRD analysis using a Bruker D8 Advance X-ray diffractometer with a Cu K\u03b1 X-ray source. Measurements were performed with a 2\u03b8 range of 10\u00b0\u201380\u00b0. Scanning electron microscope (SEM) images were taken and an energy dispersive spectrometer (EDS) analysis of the films was performed using a Verios 460, FEI and XFlash 6130, Bruker, respectively, operated at an accelerating voltage of 10 kV.", "question": "What's the electrolyte?", "answer": "NASICON ", "answer_start": 4}
{"document_id": 75783, "context": "Lithium conducting garnets are attractive solid electrolytes for solid-state lithium batteries but are difficult to process, generally requiring high reaction and sintering temperatures with long durations. In this work, we demonstrate a synthetic route to obtain Ta-doped garnet (Li6.4La3Zr1.4Ta0.6O12) utilizing La- and Ta-doped lanthanum zirconate (La2.4Zr1.12Ta0.48O7.04) pyrochlore nanocrystals as quasi-single-source precursors. Via molten salt synthesis (MSS) in a highly basic flux, the pyrochlore nanocrystals transform to Li-garnet at reaction temperatures as low as 400 \u00b0C. We also show that the pyrochlore-to-garnet conversion can take place in one step using reactive sintering, resulting in densified garnet ceramics with high ionic conductivity (0.53 mS cm\u22121 at 21 \u00b0C) and relative density (up to 94.7%). This approach opens new avenues for lower temperature synthesis of lithium garnets using a quasi-single-source precursor and provides an alternative route to highly dense garnet solid electrolytes without requiring advanced sintering processes.", "question": "What's the electrolyte?", "answer": "Lithium conducting garnets ", "answer_start": 0}
{"document_id": 75783, "context": "Lithium conducting garnets are attractive solid electrolytes for solid-state lithium batteries but are difficult to process, generally requiring high reaction and sintering temperatures with long durations. In this work, we demonstrate a synthetic route to obtain Ta-doped garnet (Li6.4La3Zr1.4Ta0.6O12) utilizing La- and Ta-doped lanthanum zirconate (La2.4Zr1.12Ta0.48O7.04) pyrochlore nanocrystals as quasi-single-source precursors. Via molten salt synthesis (MSS) in a highly basic flux, the pyrochlore nanocrystals transform to Li-garnet at reaction temperatures as low as 400 \u00b0C. We also show that the pyrochlore-to-garnet conversion can take place in one step using reactive sintering, resulting in densified garnet ceramics with high ionic conductivity (0.53 mS cm\u22121 at 21 \u00b0C) and relative density (up to 94.7%). This approach opens new avenues for lower temperature synthesis of lithium garnets using a quasi-single-source precursor and provides an alternative route to highly dense garnet solid electrolytes without requiring advanced sintering processes.", "question": "What's the electrolyte?", "answer": "garnet ", "answer_start": 991}
{"document_id": 75788, "context": "In this work, a low upper cut-off voltage of 4.5 V after an initial activation at 4.6 V is proposed and the effects of upper cut-off voltages (4.8 V and 4.5 V) on the stability of cationic/anionic redox chemistries are also studied. We demonstrate the significantly improved reversibility of cationic/anionic redox processes at the low cut-off voltage and the mitigated structural transitions from layered to rock-salt phases along with a valence decrease of Mn ions. Consequently, the LLOs present outstanding capacity/voltage stability over long-term cycling (capacity/voltage retention of 95.2%/92.2% after 200 cycles at 0.5C). The assembled mesocarbon microbead (MCMB)|LLO full cells deliver a high energy density of above 300 W h kg\u22121 and superior cycling/voltage stability. Compared with the previously proposed methods, this strategy is simpler and enables the use of conventional electrolytes rather than high-voltage ones that have not yet been widely commercialized up to now, which will promote the practical application of LLOs in high energy-density LIBs.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75786, "context": "In summary, a compressible and elastic N-doped porous carbon nanofiber aerogel was prepared with rGO-wrapped crossed PCNFs and coiled PCNFs as mechanically reinforced structures to support the frameworks. Meanwhile, a hierarchical and porous architecture with open-cell structures existed in N-PCNFAs, which provided plenty of short paths for electrolyte diffusion and enough area for electrochemical double-layer capacitance when N-PCNFAs served as self-supporting and binder-free electrodes. Moreover, N atoms were also introduced into PCNFs as active sites for faradaic redox reactions. Thus, as supercapacitor electrodes, the N-PCNFAs exhibited a high specific capacitance of 279 F g\u22121 at 0.5 A g\u22121, with a rate performance of 59% at 20 A g\u22121. They even reached a capacitance retention of 122% after 10000 cycles because of the N-induced electro-activation, steadily improved wettability of the electrodes during fast charging and discharging, and stable frameworks of N-PCNFAs. Finally, this work presents a wise and simple strategy to prepare CNF-based aerogels with hierarchical structures and heteroatom doping, which also exhibit excellent compressibility and elasticity. These characteristics make them good candidates for energy storage, sensors, adsorption and catalytic materials.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75812, "context": "The Li+ transport kinetics at the solid\u2013solid electrode|electrolyte interfaces are crucial for the stable and durable performance of solid-state batteries (SSBs). A poor interface due to mechanical problems and/or (electro-)chemical instabilities will curtail the performance of such batteries. Herein, we present a detailed study on the interfaces of a lithium\u2013sulfur (Li\u2013S) SSB with a Li anode, Li\u2013garnet (LLZO) solid electrolyte (SE), and a sulfur\u2013carbon composite as the cathode. Interlayer gels based on ionic liquids were introduced to improve the interfacial properties of the system. For Li symmetric cells, the strategy resulted in a decrease in cell resistance by about a factor of five and stable voltage profiles with low overpotentials (\u223c300 mV at 0.4 mA cm\u22122 after >450 hours). Furthermore, the LLZO SE efficiently blocked the polysulfide shuttle to the Li anode. Due to the advantageous features of the design, good electrochemical performance was obtained, where the Li\u2013S SSB delivered an initial discharge capacity of ca. 1360 mA h gsulfur\u22121 and a discharge capacity of ca. 570 mA h gsulfur\u22121 after 100 cycles. Detailed electrochemical and compositional characterization of the interphase layers was performed at the Li anode and sulfur cathode interfaces through X-ray photoelectron spectroscopy (XPS), applying depth-profiling techniques, and scanning transmission electron microscopy (STEM). The results revealed the presence of interphase nano-layers with varying thicknesses on the LLZO surface which contained organic and inorganic species.", "question": "What's the anode?", "answer": "Li ", "answer_start": 387}
{"document_id": 75812, "context": "The Li+ transport kinetics at the solid\u2013solid electrode|electrolyte interfaces are crucial for the stable and durable performance of solid-state batteries (SSBs). A poor interface due to mechanical problems and/or (electro-)chemical instabilities will curtail the performance of such batteries. Herein, we present a detailed study on the interfaces of a lithium\u2013sulfur (Li\u2013S) SSB with a Li anode, Li\u2013garnet (LLZO) solid electrolyte (SE), and a sulfur\u2013carbon composite as the cathode. Interlayer gels based on ionic liquids were introduced to improve the interfacial properties of the system. For Li symmetric cells, the strategy resulted in a decrease in cell resistance by about a factor of five and stable voltage profiles with low overpotentials (\u223c300 mV at 0.4 mA cm\u22122 after >450 hours). Furthermore, the LLZO SE efficiently blocked the polysulfide shuttle to the Li anode. Due to the advantageous features of the design, good electrochemical performance was obtained, where the Li\u2013S SSB delivered an initial discharge capacity of ca. 1360 mA h gsulfur\u22121 and a discharge capacity of ca. 570 mA h gsulfur\u22121 after 100 cycles. Detailed electrochemical and compositional characterization of the interphase layers was performed at the Li anode and sulfur cathode interfaces through X-ray photoelectron spectroscopy (XPS), applying depth-profiling techniques, and scanning transmission electron microscopy (STEM). The results revealed the presence of interphase nano-layers with varying thicknesses on the LLZO surface which contained organic and inorganic species.", "question": "What's the anode?", "answer": "Li ", "answer_start": 868}
{"document_id": 75798, "context": "CV measurements were conducted on an electrochemical workstation (CHI660A, USA) with glassy carbon as the working electrode (CHI104) and lithium metal as both the reference and counter electrode. A Fc/Fc+ redox couple serves as an internal reference (3.2 V vs. Li+/Li). Standard CR2032 coin cells were assembled inside an Ar-filled glovebox with a 2035 Celgard separator. 30 \u03bcL electrolyte was added to each coin cell with barely any electrolyte spilled out during cell crimping. Galvanostatic charge\u2013discharge studies were conducted on a battery cycler (CT2001D, LAND Electronics Co., China). Before assembling full cells, the Si\u2013C anodes were assembled into half-cells for pre-lithiation, which can reduce the initial irreversible capacity. All cells went through three formation cycles at 0.05C, 0.1C and 0.2C, respectively, until the current dropped below 0.05C.", "question": "What's the anode?", "answer": "Si\u2013C ", "answer_start": 628}
{"document_id": 75798, "context": "CV measurements were conducted on an electrochemical workstation (CHI660A, USA) with glassy carbon as the working electrode (CHI104) and lithium metal as both the reference and counter electrode. A Fc/Fc+ redox couple serves as an internal reference (3.2 V vs. Li+/Li). Standard CR2032 coin cells were assembled inside an Ar-filled glovebox with a 2035 Celgard separator. 30 \u03bcL electrolyte was added to each coin cell with barely any electrolyte spilled out during cell crimping. Galvanostatic charge\u2013discharge studies were conducted on a battery cycler (CT2001D, LAND Electronics Co., China). Before assembling full cells, the Si\u2013C anodes were assembled into half-cells for pre-lithiation, which can reduce the initial irreversible capacity. All cells went through three formation cycles at 0.05C, 0.1C and 0.2C, respectively, until the current dropped below 0.05C.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75806, "context": "Electrides are a unique class of materials, where the electron density is neither localised at an atomic orbital nor fully delocalised like in metals. Instead, their electrons occupy interstitial regions formed by cavities in the crystal structure, where they act as anions. Materials with anionic electrons offer versatile functionalities, such as high electrical conductivity, ultra-low work function, and non-linear optical responses, ranging their applications as electron emitters, battery anodes, and agent catalysts.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75806, "context": "Electrides are a unique class of materials, where the electron density is neither localised at an atomic orbital nor fully delocalised like in metals. Instead, their electrons occupy interstitial regions formed by cavities in the crystal structure, where they act as anions. Materials with anionic electrons offer versatile functionalities, such as high electrical conductivity, ultra-low work function, and non-linear optical responses, ranging their applications as electron emitters, battery anodes, and agent catalysts.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75810, "context": "Wide Angle X-ray Scattering (WAXS) experiments were performed by a Rigaku three pinholes camera, coupled to an Fr-E+ superbright rotating anode microsource (Cu K\u03b1, \u03bb = 0.15405 nm) through a focusing Confocal Max Flux optics (CMF 15-105). Beam diameter was 0.2 mm. Sample-to-detector distance was 28 mm, calibrated by LaB6 powder standard. The sample was raster scanned with a 0.2 mm lateral step, in order to obtain an average pattern from a large crystal volume. 2D WAXS data were centered and calibrated using LaB6 standard and the corresponding 1D WAXS profiles were derived by SUNBIM software.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75810, "context": "Wide Angle X-ray Scattering (WAXS) experiments were performed by a Rigaku three pinholes camera, coupled to an Fr-E+ superbright rotating anode microsource (Cu K\u03b1, \u03bb = 0.15405 nm) through a focusing Confocal Max Flux optics (CMF 15-105). Beam diameter was 0.2 mm. Sample-to-detector distance was 28 mm, calibrated by LaB6 powder standard. The sample was raster scanned with a 0.2 mm lateral step, in order to obtain an average pattern from a large crystal volume. 2D WAXS data were centered and calibrated using LaB6 standard and the corresponding 1D WAXS profiles were derived by SUNBIM software.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75809, "context": "(4) PEC: a typical PEC process (Fig. 9D) could be regarded as a combination of electrocatalysis, photocatalysis and their synergistic effects from mechanism. On one hand, electrocatalysis could generate functional radicals (e.g. \u02d9OH) to degrade oxidizable contaminants at the anode and reduce others at the cathode. On the other hand, the photocatalysis subprocess excites e\u2212/h+ to degrade the existing pollutants. In particular, the electrons generated by photocatalysis could migrate along the electric field to the counter electrode by the utilized positive potential (Fig. 9D), which contributes to the reduction of photo-generated holes' and electrons' recombination and thus enhancement of photocatalytic performance. In other words, the increase of bias potential would not only enhance the separation of excitons but also elevate the degree of the electrochemical reaction, which would contribute to the acceleration of PEC performance.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75809, "context": "(4) PEC: a typical PEC process (Fig. 9D) could be regarded as a combination of electrocatalysis, photocatalysis and their synergistic effects from mechanism. On one hand, electrocatalysis could generate functional radicals (e.g. \u02d9OH) to degrade oxidizable contaminants at the anode and reduce others at the cathode. On the other hand, the photocatalysis subprocess excites e\u2212/h+ to degrade the existing pollutants. In particular, the electrons generated by photocatalysis could migrate along the electric field to the counter electrode by the utilized positive potential (Fig. 9D), which contributes to the reduction of photo-generated holes' and electrons' recombination and thus enhancement of photocatalytic performance. In other words, the increase of bias potential would not only enhance the separation of excitons but also elevate the degree of the electrochemical reaction, which would contribute to the acceleration of PEC performance.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75809, "context": "(4) PEC: a typical PEC process (Fig. 9D) could be regarded as a combination of electrocatalysis, photocatalysis and their synergistic effects from mechanism. On one hand, electrocatalysis could generate functional radicals (e.g. \u02d9OH) to degrade oxidizable contaminants at the anode and reduce others at the cathode. On the other hand, the photocatalysis subprocess excites e\u2212/h+ to degrade the existing pollutants. In particular, the electrons generated by photocatalysis could migrate along the electric field to the counter electrode by the utilized positive potential (Fig. 9D), which contributes to the reduction of photo-generated holes' and electrons' recombination and thus enhancement of photocatalytic performance. In other words, the increase of bias potential would not only enhance the separation of excitons but also elevate the degree of the electrochemical reaction, which would contribute to the acceleration of PEC performance.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75661, "context": "The potential of the respective working electrode Ewe and the electrolyte redox potential Esol as function of charge/discharge cycles are shown in Fig. 8a and c. Averaged overpotentials (, see eqn (3)) and CE per cycle for [FeII/III-racEDDHA] and [FeII/III(CN)6] are shown in Fig. 8b and d. In case of [FeII/III(CN)6] a time stable value for was obtained. In case of the [Fe-racEDDHA] complex even a slight decrease in was observed. Thus, no deactivation of the carbon electrode surface was measured during repetitive cycling. Excellent CE was observed for both redox systems, indicating the absence of parasitic side reactions and suggesting a good electrochemical stability of all electrochemically active species. The applied procedure of desizing and anodic activation of the CRLE lead to formation of a stable and active carbon surface, which is not degraded or passivated during extended electrolysis. Independent on electrode potential, passivation was not observed in the potential window between +800 mV and \u22121200 mV vs. Ag/AgCl, which demonstrates the high chemical stability of the surface towards electrochemical degradation processes at the chosen experimental conditions.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75676, "context": "\u2022 Challenge: reality often deviates from theory. Because most metal sulfides are electrochemically active, lithium-inserted products are LiyMSx rather than pristine MSx. These materials strongly influence the behaviors of Li\u2013S batteries but have long been overlooked in theoretical calculations. Solvation also plays an important role in triggering the ionization of LiPSs into solvated Li+ (electrolyte) cations and Sn2\u2212 (electrolyte) anions. Therefore, relying on the calculated binding energies of Li2Sx species rather than solvated Li+ (electrolyte) cations might lead to misleading results. There remains a need to optimize theoretical models to enhance the rationality and reliability of computation results.", "question": "What's the electrolyte?", "answer": "solvated Li+ (electrolyte) cations and Sn2\u2212 (electrolyte) anions", "answer_start": 378}
{"document_id": 75676, "context": "\u2022 Challenge: reality often deviates from theory. Because most metal sulfides are electrochemically active, lithium-inserted products are LiyMSx rather than pristine MSx. These materials strongly influence the behaviors of Li\u2013S batteries but have long been overlooked in theoretical calculations. Solvation also plays an important role in triggering the ionization of LiPSs into solvated Li+ (electrolyte) cations and Sn2\u2212 (electrolyte) anions. Therefore, relying on the calculated binding energies of Li2Sx species rather than solvated Li+ (electrolyte) cations might lead to misleading results. There remains a need to optimize theoretical models to enhance the rationality and reliability of computation results.", "question": "What's the electrolyte?", "answer": "solvated Li+ (electrolyte) ", "answer_start": 527}
{"document_id": 75680, "context": "In contrast, for the higher constant current of 2 mA cm\u22122, a close to constant intensity of the metal peak is observed for both electrolyte systems, with a slight increase occurring after passing 5 coulombs (3.25 mA h cm\u22122, Fig. 3e). Now mNMR is only slightly lower than mechem for both electrolytes, indicating a higher current efficiency for the LP30 electrolyte at 2 mA cm\u22122. This is tentatively ascribed to the competing reactions of SEI formation and Li deposition where at higher overpotentials, electrodeposition of Li metal occurs more rapidly than the kinetically-limited degradation reaction involving the electrolyte species. The morphology of the lithium deposits for the two electrodes is now very similar (Fig. S7\u2020).", "question": "What's the electrolyte?", "answer": "LP30", "answer_start": 348}
{"document_id": 75689, "context": "Implementability of Mg metal as an anode in magnesium-ion batteries (MIBs) mostly results from the dendrite-free nature of Mg during electrochemical plating/stripping, although it has been recently reported that the dendritic growth of Mg is dependent on the electrolyte nature and current densities. This feature provides potentially significant advantages to battery fabrication and/or electrochemical performance. For example, Mg metal delivers a higher volumetric capacity (3833 mA h cm\u22123) than either graphite (841 mA h cm\u22123) or Li metal (2047 mA h cm\u22123) in lithium-ion batteries, which enables cell designs that are more compact and flexible. The natural abundance of Mg (29k ppm in the Earth\u2019s crust) is an additional benefit, in comparison with the limits of Li as a natural resource. The reversibility of Mg plating/stripping, however, is quite sensitive to the electrolyte system. The passivation of the Mg surface in conventional electrolytes restricts the versatility of utilizable electrolytes. To overcome this problem, various types of specially designed Mg-compatible electrolytes have been introduced during the past few decades: \u2018all phenyl complex\u2019 (APC); \u2018magnesium aluminum chloride complex\u2019 (MACC); [(DTBP)MgCl + MgCl2] (DTBP = 2,6-di-tert-butylphenolate); and [PhMgCl + MgCl2]. These electrolytes have shown reasonable levels of reversibility for Mg plating/stripping, but the relatively low anodic stability (\u2264ca. 3.0 V vs. Mg/Mg2+) and/or the difficulty in reaching high coulombic efficiencies remain problematic if MIBs are to move one step closer to commercialization.", "question": "What's the anode?", "answer": "Mg metal", "answer_start": 20}
{"document_id": 75689, "context": "Implementability of Mg metal as an anode in magnesium-ion batteries (MIBs) mostly results from the dendrite-free nature of Mg during electrochemical plating/stripping, although it has been recently reported that the dendritic growth of Mg is dependent on the electrolyte nature and current densities. This feature provides potentially significant advantages to battery fabrication and/or electrochemical performance. For example, Mg metal delivers a higher volumetric capacity (3833 mA h cm\u22123) than either graphite (841 mA h cm\u22123) or Li metal (2047 mA h cm\u22123) in lithium-ion batteries, which enables cell designs that are more compact and flexible. The natural abundance of Mg (29k ppm in the Earth\u2019s crust) is an additional benefit, in comparison with the limits of Li as a natural resource. The reversibility of Mg plating/stripping, however, is quite sensitive to the electrolyte system. The passivation of the Mg surface in conventional electrolytes restricts the versatility of utilizable electrolytes. To overcome this problem, various types of specially designed Mg-compatible electrolytes have been introduced during the past few decades: \u2018all phenyl complex\u2019 (APC); \u2018magnesium aluminum chloride complex\u2019 (MACC); [(DTBP)MgCl + MgCl2] (DTBP = 2,6-di-tert-butylphenolate); and [PhMgCl + MgCl2]. These electrolytes have shown reasonable levels of reversibility for Mg plating/stripping, but the relatively low anodic stability (\u2264ca. 3.0 V vs. Mg/Mg2+) and/or the difficulty in reaching high coulombic efficiencies remain problematic if MIBs are to move one step closer to commercialization.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75491, "context": "The electrochemical data were collected using assembled 2032-coin cells. The cathode electrode was prepared by mixing the as-prepared MVO microspheres or V2O5\u00b7nH2O, carbon black and polytetrafluoroethylene (PTFE) binder in a weight ratio of 6:3:1. The coin cells were assembled using the prepared cathode, zinc metal as the anode, and the prepared PAM\u2013CNF film as the electrolyte and separator. Galvanostatic charge/discharge electrochemical tests were performed on an eight-channel LAND battery analyzer (CT3001A, LAND Electronics Corporation, Wuhan, China) in the voltage range of 0.2\u20131.6 V. Cyclic voltammetry (CV) measurements were carried out on an electrochemical workstation (CHI 760e) in the potential range of 0.2\u20131.6 V. Electrochemical impedance spectroscopy (EIS) was carried out by applying an AC potential of 5 mV amplitude in the frequency range of 0.01\u2013100 kHz. A freeze-resistance test was carried out at \u221218 \u00b0C in a freezer. Heat-resistance properties were tested in an EQ-DHG-9015 oven (MTI Inc., Richmond, CA, USA).", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75530, "context": "Both chemical and mechanical instabilities play a role in the impedance build-up and capacity fade during SSB cycling. Chemical reactivity issues between conductor and cathode have been well-studied theoretically and experimentally. In this work, we focus on the mechanical failure modes of an SSB composite cathode. The latter consists of an intimate mixture of the solid electrolyte and active cathode particles so that a transport path exists for the Li ions to/from the cathode particles. Good Li-ion transport across the solid electrolyte/cathode particle interface is necessary to minimize the cell resistance and overpotential of the composite cathode. Chemical reactivity at the solid electrolyte/cathode interface can lead to the formation of a reaction layer, which increases cathode impedance. For example, sulfide-based electrolytes have been shown to react with oxide-based cathodes, resulting in overpotential growth and capacity fade. Coating the cathode particles has been shown to mitigate this issue to some extent and improve cycling stability.", "question": "What's the cathode?", "answer": "SSB composite", "answer_start": 294}
{"document_id": 75513, "context": "Herein, we designed a type of NiAs-type structured V2S3 nanoparticle by a one-step vulcanization reaction under Ar. The results showed the resultant carbon nanofiber (CNF)@V2S3 composite films show an improved conductance and a high flexibility, which is due to the high conductivity of V2S3 and the catalytic effect of V atoms on the carbonization treatment of CNFs. And the sulfur loaded carbon nanofiber@V2S3 (CNF@V2S3/S) composite cathodes showed a high specific capacitance of 1200 mA h g\u22121 at 0.1C, an excellent rate capability (retain 78.9% at 2.0C), and an ultralow decay rate per cycle (0.0071% at 2.0C for 1000 cycles). This high rate capability as well as high cycling stability could be due to the high polarity and catalytic activity, and improved conductivity of V2S3 nanocrystals. Furthermore, the enhancement mechanisms of energy storage and reaction kinetics of the composite cathodes via V2S3 have also been discussed.", "question": "What's the cathode?", "answer": "carbon nanofiber@V2S3 (CNF@V2S3/S) composite ", "answer_start": 390}
{"document_id": 75518, "context": "The lithium-ion battery, which can convert chemical energy to electric energy, has been widely used in portable devices, such as the laptops and mobile phones. However, the pressing demand for high capacity and stability is yet to be solved, especially the cathode, which has been the bottleneck of battery capacity. The Li-rich layered oxide has gained much attention due to the extremely high capacity of over 280 mA h g\u22121. Recent research has revealed that the extra capacity in the Li-rich oxide comes from the participation in oxygen redox. The complex chemical and structural evolution of the Li-rich cathode has attracted extensive efforts, however, the critical problem of voltage decay remains unsolved with its elusive mechanism.", "question": "What's the cathode?", "answer": " Li-rich ", "answer_start": 598}
{"document_id": 75654, "context": "Combining the insights derived from the systematic set of experiments detailed in this report along with complimentary results from literature, we have uncovered a new understanding of the mechanisms underlying the growth of columnar lithium metal. A schematic representation of the proposed mechanism linking electrolyte additive concentration, initial SEI formation, and the resulting growth of lithium columns is shown in Fig. 13. The initially pristine, oxide-free copper surface enables the electrocatalytic reduction of HF at \u223c2 V vs. Li/Li+ which forms (111) textured LiF deposits a few nanometers in size on the surface. Two morphologically distinct yet functionally equivalent LiF deposit morphologies are possible \u2013 uniform yet discontinuous LiF particles decorating the copper surface or a continuous polycrystalline film \u2013 with the former being more probable in this system when considering the substrate roughness and LiF crystallite size. This HF reduction and LiF deposition process slows significantly when HF becomes depleted near the interface. Subsequently, as the potential drops below 1 V, solvent molecules are decomposed on the remaining unpassivated surfaces between and/or on top of LiF particles, forming organic reduction products and slowing further reduction of electrolyte species. While the precise morphology of the LiF particle layer could not be directly imaged, both candidate morphologies shown schematically in Fig. 13 would result in an SEI with similar properties and identical effects on lithium nucleation and growth. Interfaces between individual crystalline LiF particles and/or between LiF particles and the amorphous matrix of solvent reduction products in the initial SEI act as fast lithium-ion diffusion pathways. These pathways serve to homogenize the electronic and ionic properties near the copper surface, enabling a high nucleation density of lithium metal as the potential of the working electrode is brought below 0 V vs. Li/Li+ and electrodeposition of the active material begins via an instantaneous nucleation event. High lithium-ion diffusion within the SEI created by these interfaces, which allows for easier movement of lithium ions laterally across the electrode surface, along with the layer being very thin, allow for uniform, lateral growth of the lithium metal deposits until they bump into one another. After lateral growth is inhibited the deposits are restricted to growing vertically, normal to the working electrode, resulting in the highly monodisperse (110) textured columnar morphology observed. The diameter of these lithium columns can be controlled by varying the current density during electrodeposition (Fig. S8\u2020). Indeed, a columnar morphology may be the intrinsically preferred growth mode of lithium metal. However, such growth may be inhibited by the SEI formed in conventional electrolytes without additives due to non-uniform lithium-ion diffusivity and the presence of \u201chot spots\u201d where preferential deposition occurs, whereas the nanostructured SEI formed in electrolytes with added HF would allow columnar growth to proceed uninhibited.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75433, "context": "In comparison with MnOx, NiO and Co3O4, TiO2 with lower theoretical capacitance has also been tested as an electrode in SCs. For instance, by using TiO2 nanofibers, activated carbon and a PVA\u2013H3PO4 membrane, a solid-state SC was fabricated, which delivered a specific capacitance of 310 F g\u22121. Recently, Ta-doped TiO2 nanofibers were synthesized through the electrospinning technique. In 1 M H2SO4, the 2% Ta-doped TiO2 nanofibers could deliver nearly two times higher specific capacitance than the undoped TiO2 counterpart (111 F g\u22121), which was attributed to the enhanced electronic conductivity of TiO2 stemming from the replacement of Ti4+ by Ta5+ in the lattice after doping. In addition to the most studied metal oxides mentioned above, Fe2O3, V2O5 and CuO have also been applied to SCs as electrodes. The first report on a pure iron oxide electrode composed of particles with sizes of 53 nm has demonstrated a specific capacitance of 256 F g\u22121 in 1 M LiOH. Recently, both interconnected Fe2O3 and V2O5 nanofibers with rich meso-/macro-pores were obtained via electrospinning and subsequent heat treatment. Owing to the hierarchical porous structure that acts as an excellent conductive highway for efficient electronic transfer and ion permeation, the resultant binder-free Fe2O3 and V2O5 electrodes gave specific capacitances of 255 F g\u22121 and 256 F g\u22121, respectively, at 2 mV s\u22121 in 1 M Na2SO4. Moreover, an all-solid-state ASC based on an Fe2O3 negative electrode and V2O5 positive electrode could be operated at up to 1.8 V and displayed a high energy density of 32.2 W h kg\u22121 at an average power density of 128.7 W kg\u22121. In 2012, pure electrospun V2O5 nanofibers with different structures have been synthesized and tested in two studies. These pure electrospun V2O5 nanofibers displayed a capacitance of around 200 F g\u22121 in both the studies. A high specific capacitance of 620 F g\u22121 (accounting for \u223c35% of their theoretical capacitance) at 2 A g\u22121 in 6 M KOH was reported by Jose et al. for electrospun CuO nanowires in 2014. In another reference, an ASC device based on electrospun CuO nanowires as the anode and AC as the cathode was constructed and provided an enhanced voltage window (1.6 V), specific capacitance (83 F g\u22121), and threefold higher energy density (29.5 W h kg\u22121) than the AC-based symmetric capacitor (1.4 V, 33 F g\u22121, 11 W h kg\u22121).", "question": "What's the cathode?", "answer": "AC", "answer_start": 2126}
{"document_id": 75433, "context": "In comparison with MnOx, NiO and Co3O4, TiO2 with lower theoretical capacitance has also been tested as an electrode in SCs. For instance, by using TiO2 nanofibers, activated carbon and a PVA\u2013H3PO4 membrane, a solid-state SC was fabricated, which delivered a specific capacitance of 310 F g\u22121. Recently, Ta-doped TiO2 nanofibers were synthesized through the electrospinning technique. In 1 M H2SO4, the 2% Ta-doped TiO2 nanofibers could deliver nearly two times higher specific capacitance than the undoped TiO2 counterpart (111 F g\u22121), which was attributed to the enhanced electronic conductivity of TiO2 stemming from the replacement of Ti4+ by Ta5+ in the lattice after doping. In addition to the most studied metal oxides mentioned above, Fe2O3, V2O5 and CuO have also been applied to SCs as electrodes. The first report on a pure iron oxide electrode composed of particles with sizes of 53 nm has demonstrated a specific capacitance of 256 F g\u22121 in 1 M LiOH. Recently, both interconnected Fe2O3 and V2O5 nanofibers with rich meso-/macro-pores were obtained via electrospinning and subsequent heat treatment. Owing to the hierarchical porous structure that acts as an excellent conductive highway for efficient electronic transfer and ion permeation, the resultant binder-free Fe2O3 and V2O5 electrodes gave specific capacitances of 255 F g\u22121 and 256 F g\u22121, respectively, at 2 mV s\u22121 in 1 M Na2SO4. Moreover, an all-solid-state ASC based on an Fe2O3 negative electrode and V2O5 positive electrode could be operated at up to 1.8 V and displayed a high energy density of 32.2 W h kg\u22121 at an average power density of 128.7 W kg\u22121. In 2012, pure electrospun V2O5 nanofibers with different structures have been synthesized and tested in two studies. These pure electrospun V2O5 nanofibers displayed a capacitance of around 200 F g\u22121 in both the studies. A high specific capacitance of 620 F g\u22121 (accounting for \u223c35% of their theoretical capacitance) at 2 A g\u22121 in 6 M KOH was reported by Jose et al. for electrospun CuO nanowires in 2014. In another reference, an ASC device based on electrospun CuO nanowires as the anode and AC as the cathode was constructed and provided an enhanced voltage window (1.6 V), specific capacitance (83 F g\u22121), and threefold higher energy density (29.5 W h kg\u22121) than the AC-based symmetric capacitor (1.4 V, 33 F g\u22121, 11 W h kg\u22121).", "question": "What's the anode?", "answer": "CuO nanowires", "answer_start": 2095}
{"document_id": 75442, "context": "In order to demonstrate their remarkable performance for electrochemical energy storage in portable and wearable electronics, we assembled the flexible quasi-solid-state ARZIBs using the NV NSs@ACC as the cathode together with the Zn NSs@CC anode (deposited Zn nanosheets on CC). Fig. S7a\u2020 depicts the crystal structure of Zn NSs@CC, in which all the peaks were in good accordance with those of hexagonal Zn (JCPDS no. 87-0713). Furthermore, the SEM images of Zn NSs@CC are illustrated in Fig. S7b.\u2020 It is clearly observed that the Zn nanosheets are uniformly grown on CC. The cycling performance of the as-assembled flexible ZIB at 0.2 A g\u22121 is depicted in Fig. 6a. The device achieves an initial discharge capacity of 121 mA h g\u22121 and a reversible capacity of 91 mA h g\u22121 can be maintained after 50 cycles. Furthermore, it can deliver a specific capacity of 60 mA h g\u22121 and maintain a stable capacity of 52 mA h g\u22121 after 1000 cycles with excellent coulombic efficiency (\u223c100%) at a high current density of 1.0 A g\u22121 (Fig. 6b), which can be ascribed to the stable 2D ultrathin nanosheets structure and the free-standing feature. The flexible quasi-solid-state ARZIB device was bent into three mechanical states to further evaluate its flexibility (Fig. 6c). As presented in Fig. 6d and e, there are no evident changes in the EIS spectra and capacity decline (>92% retention) under different bending states, demonstrating the extraordinary structural durability of our flexible quasi-solid-state ARZIB devices. As a demonstration of the practical application, two series-connected devices were shown to successfully illuminate a red light-emitting diode (LED, 1.8 V) (inset of Fig. 6e). These significant results indicate that this flexible quasi-solid-state ARZIB device holds potential promise for powering future portable and wearable electronics.", "question": "What's the cathode?", "answer": "NV NSs@ACC", "answer_start": 187}
{"document_id": 75442, "context": "In order to demonstrate their remarkable performance for electrochemical energy storage in portable and wearable electronics, we assembled the flexible quasi-solid-state ARZIBs using the NV NSs@ACC as the cathode together with the Zn NSs@CC anode (deposited Zn nanosheets on CC). Fig. S7a\u2020 depicts the crystal structure of Zn NSs@CC, in which all the peaks were in good accordance with those of hexagonal Zn (JCPDS no. 87-0713). Furthermore, the SEM images of Zn NSs@CC are illustrated in Fig. S7b.\u2020 It is clearly observed that the Zn nanosheets are uniformly grown on CC. The cycling performance of the as-assembled flexible ZIB at 0.2 A g\u22121 is depicted in Fig. 6a. The device achieves an initial discharge capacity of 121 mA h g\u22121 and a reversible capacity of 91 mA h g\u22121 can be maintained after 50 cycles. Furthermore, it can deliver a specific capacity of 60 mA h g\u22121 and maintain a stable capacity of 52 mA h g\u22121 after 1000 cycles with excellent coulombic efficiency (\u223c100%) at a high current density of 1.0 A g\u22121 (Fig. 6b), which can be ascribed to the stable 2D ultrathin nanosheets structure and the free-standing feature. The flexible quasi-solid-state ARZIB device was bent into three mechanical states to further evaluate its flexibility (Fig. 6c). As presented in Fig. 6d and e, there are no evident changes in the EIS spectra and capacity decline (>92% retention) under different bending states, demonstrating the extraordinary structural durability of our flexible quasi-solid-state ARZIB devices. As a demonstration of the practical application, two series-connected devices were shown to successfully illuminate a red light-emitting diode (LED, 1.8 V) (inset of Fig. 6e). These significant results indicate that this flexible quasi-solid-state ARZIB device holds potential promise for powering future portable and wearable electronics.", "question": "What's the anode?", "answer": "Zn NSs@CC", "answer_start": 231}
{"document_id": 75446, "context": "In this contribution, we propose the use of a small amount of metallic 1T MoS2 nanodots (NDs, 3 wt% of the electrode) as a robust catalyst for advanced LSBs. Electrochemical tests and synchrotron in situ X-ray diffraction (XRD) characterizations demonstrated the strong anchoring and catalytic capability of MoS2 NDs. When MoS2 NDs were integrated with a porous carbon/catholyte, the new cathodes exhibited remarkable battery performance, including a high rate capacity of 8.5 mA h cm\u22122 at 1C and an impressive capacity retention of 9.3 mA h cm\u22122 after 300 cycles under a high sulfur loading of 12.9 mg cm\u22122, an extremely low E/S ratio of 4.6 \u03bcL mg\u22121, and a remarkable sulfur content of 81 wt%. Such high-energy densities delivered under high sulfur loading and lean electrolyte conditions are among the best reported so far for LSBs. Based on DFT calculations, we found that the phase and edge sites were the key to governing the catalytic capability for MoS2. Li2S anchored preferentially at Mo-terminated edges of MoS2 and the electrochemical dissociation occurred toward the surface of the monolayer where Li ions could diffuse faster. Indeed, the metallic 1T MoS2 showed a stronger affinity to polysulfides and a lower activation energy for Li2S than 2H MoS2 at most of the adsorption sites. These findings suggest that the catalytic activity in MoS2 can be maximized by downsizing 2H MoS2 flakes to 1T MoS2 NDs.", "question": "What's the cathode?", "answer": "MoS2 NDs", "answer_start": 323}
{"document_id": 75449, "context": "(4) Photoelectrocatalysis (PEC): PEC is a special electricity-driven photocatalytic process which could be regarded as a combination of electrocatalysis and photocatalysis. In a typical PEC cell, the photocatalysts are usually immobilized on a conductive substrate as the anode and a bias potential as well as continuous illumination are then applied to the prepared anode to generate functional radicals to remove the contaminants. In particular, it should be mentioned that the separation of photo-induced charge carriers could be significantly enhanced by the utilized bias potential since the electrons generated by photocatalysis follow the electric field to the cathode, which contributes to the reduction of the recombination rate. As a result, the photoelectrocatalytic method would significantly promote the degradation efficiency of the titanate materials. For example, Chang et al. synthesized a Cu2O/titanate composite for photocatalytic and photoelectrocatalytic degradation of ibuprofen. The results indicated that the pseudo-first rate constant could be increased from 0.804 h\u22121 for photocatalysis to 2.28 h\u22121 for PEC. Finally, the morphology modulation, trap doping and compositing strategies were also extensively applied in PEC to further enhance the separation of charge carriers, for example, layer stacking (morphology modulation), Fe-modification (trap doping) and ZnO compositing (compositing) could significantly improve the PEC performance compared to that of pristine titanate characterized by the increased photocurrent under illumination.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75449, "context": "(4) Photoelectrocatalysis (PEC): PEC is a special electricity-driven photocatalytic process which could be regarded as a combination of electrocatalysis and photocatalysis. In a typical PEC cell, the photocatalysts are usually immobilized on a conductive substrate as the anode and a bias potential as well as continuous illumination are then applied to the prepared anode to generate functional radicals to remove the contaminants. In particular, it should be mentioned that the separation of photo-induced charge carriers could be significantly enhanced by the utilized bias potential since the electrons generated by photocatalysis follow the electric field to the cathode, which contributes to the reduction of the recombination rate. As a result, the photoelectrocatalytic method would significantly promote the degradation efficiency of the titanate materials. For example, Chang et al. synthesized a Cu2O/titanate composite for photocatalytic and photoelectrocatalytic degradation of ibuprofen. The results indicated that the pseudo-first rate constant could be increased from 0.804 h\u22121 for photocatalysis to 2.28 h\u22121 for PEC. Finally, the morphology modulation, trap doping and compositing strategies were also extensively applied in PEC to further enhance the separation of charge carriers, for example, layer stacking (morphology modulation), Fe-modification (trap doping) and ZnO compositing (compositing) could significantly improve the PEC performance compared to that of pristine titanate characterized by the increased photocurrent under illumination.", "question": "What's the anode?", "answer": "photocatalysts", "answer_start": 200}
{"document_id": 75452, "context": "Here, RGO serves as a 2D template and the carbon source to form the SiC/RGO nanocomposite by an in situ gas\u2013solid reaction. The introduction of RGO not only reduces the recombination of photogenerated electron\u2013hole pairs, but also promotes the transfer of photoexcited electrons between SiC and Li anode taking advantage of the high conductivity of RGO, which plays a crucial role in improving the performance of Li\u2013CO2 batteries. The synthesis strategy of the SiC/RGO nanocomposite is displayed in Fig. 2a. By the sublimation of the solid Si at a high temperature, a new nucleus is generated on the surface of RGO by a gas\u2013solid reaction (C(s) + Si(g) \u2192 SiC(s)), and then spreads around RGO to form a tightly connected SiC nanosheet on RGO. The morphology and the structure of RGO and SiC/RGO nanocomposite were studied by SEM and TEM. As shown in Fig. S1 (ESI\u2020), the bare RGO exhibits a 2D nanosheet morphology. After the carbothermal process, SiC is uniformly distributed on the RGO substrate, presenting a distinct island-in-sea-like morphology (Fig. 2b and c). Furthermore, the elemental distribution of the material was studied by EDS. As shown in Fig. S2,\u2020 Si is present only in the island-like region and C exists throughout the test area, which directly proves that the island-like nanosheets observed in SEM and TEM images are SiC. The partial conversion of 2D RGO to the SiC/RGO nanocomposite facilitates the transfer of high energy electrons. The high resolution TEM (HRTEM) images (Fig. 2d) also demonstrate the tight junction between SiC and RGO. Clear lattice fringes with a d-spacing of 0.25 nm on the overlay correspond well to the (111) plane of SiC. It is also possible to distinguish between carbon layers due to the pleated RGO layer in the substrate with an interplanar distance of 0.34 nm. Apart from the enhanced electronic conductivity for the SiC/RGO composites, RGO also plays an important role in enhancing the CO2 adsorption capacity (Fig. S3\u2020), which is beneficial for a higher actual discharge capacity of the cathode.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75453, "context": "In an another set of experiments, the DPP dyes 1 and 2 were cross-linked with 3 with the classical copper-catalyzed protocol by heating the photoelectrode for 10 minutes at 30 \u00b0C in a DMF solution with Cu(SO4)\u00b75H2O, sodium ascorbate in presence of the tris(benzyltriazolylmethyl)amine (TBTA) ligand. The completion of the reaction was confirmed by the ATR-IR spectroscopy (Fig. S25 and S26\u2020). The results of the photovoltaic performances of the solar cells made with the I3\u2212/I\u2212 redox couple are gathered in Table S3.\u2020 Clearly, the conditions of copper catalyzed Huisgen cycloaddition, although conducted in mild conditions, negatively impact the performances of the solar cells since the PCEs are notably lower than those measured with the thermal crosslinking activation. For TiO2 based solar cells, both Jsc and Voc were diminished upon cross-linking. Interestingly, the performances of photocathodes with NiO are less degraded than those with the photoanodes based on TiO2, because only the Jsc was decreased after copper-catalyzed cross-linking. This result is consistent with the upward shift of the valence band of NiO upon insertion of copper cation into the lattice as it was previously reported. Another possibility, is the presence of remaining Cu(II) salt, which is a paramagnetic metal that could quench the excited state of the dye and consequently diminishes the charge injection quantum yield as shown by Hanson and co-workers.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75456, "context": "Utilization of ceramic SE based separators is also an interesting strategy that can potentially solve problems associated with the S cathode and Li anode. Thanks to their high shear modulus, both the polysulfide shuttle and the Li dendrite growth can be mechanically suppressed. Among various inorganic ceramic SEs, Li\u2013garnet (LLZO) is of particular interest since it offers a relatively high (electro)-chemical stability with Li metal, a much wider potential window compared to other SEs, and a high shear modulus (61 GPa for LLZO; 4.2 GPa for Li). However, the surface impurities/roughness and brittle nature of LLZO SE restrict its intimate contact with Li and other solid-state cathode materials. With S as the cathode material, the electrode/electrolyte integration will be even more challenging considering the enormous volumetric expansion during the conversion reaction with Li. In this regard, surface modification strategies including the use of thin nanometric layer coatings, and 3D interfacial architectures, or the implementation of polymer, gel and liquid interlayers have been used to keep the electrode|SE contacts intact and stabilize the interfacial ionic transport. Using Li ion conducting gel/liquid interlayers instead of using solid interlayers may prove to be an even better strategy due to their inherent tendency to penetrate through the porous structures and hence to access a greater surface area of the composite cathode.", "question": "What's the cathode?", "answer": "S", "answer_start": 706}
{"document_id": 75456, "context": "Utilization of ceramic SE based separators is also an interesting strategy that can potentially solve problems associated with the S cathode and Li anode. Thanks to their high shear modulus, both the polysulfide shuttle and the Li dendrite growth can be mechanically suppressed. Among various inorganic ceramic SEs, Li\u2013garnet (LLZO) is of particular interest since it offers a relatively high (electro)-chemical stability with Li metal, a much wider potential window compared to other SEs, and a high shear modulus (61 GPa for LLZO; 4.2 GPa for Li). However, the surface impurities/roughness and brittle nature of LLZO SE restrict its intimate contact with Li and other solid-state cathode materials. With S as the cathode material, the electrode/electrolyte integration will be even more challenging considering the enormous volumetric expansion during the conversion reaction with Li. In this regard, surface modification strategies including the use of thin nanometric layer coatings, and 3D interfacial architectures, or the implementation of polymer, gel and liquid interlayers have been used to keep the electrode|SE contacts intact and stabilize the interfacial ionic transport. Using Li ion conducting gel/liquid interlayers instead of using solid interlayers may prove to be an even better strategy due to their inherent tendency to penetrate through the porous structures and hence to access a greater surface area of the composite cathode.", "question": "What's the anode?", "answer": "Li ", "answer_start": 145}
{"document_id": 75456, "context": "Utilization of ceramic SE based separators is also an interesting strategy that can potentially solve problems associated with the S cathode and Li anode. Thanks to their high shear modulus, both the polysulfide shuttle and the Li dendrite growth can be mechanically suppressed. Among various inorganic ceramic SEs, Li\u2013garnet (LLZO) is of particular interest since it offers a relatively high (electro)-chemical stability with Li metal, a much wider potential window compared to other SEs, and a high shear modulus (61 GPa for LLZO; 4.2 GPa for Li). However, the surface impurities/roughness and brittle nature of LLZO SE restrict its intimate contact with Li and other solid-state cathode materials. With S as the cathode material, the electrode/electrolyte integration will be even more challenging considering the enormous volumetric expansion during the conversion reaction with Li. In this regard, surface modification strategies including the use of thin nanometric layer coatings, and 3D interfacial architectures, or the implementation of polymer, gel and liquid interlayers have been used to keep the electrode|SE contacts intact and stabilize the interfacial ionic transport. Using Li ion conducting gel/liquid interlayers instead of using solid interlayers may prove to be an even better strategy due to their inherent tendency to penetrate through the porous structures and hence to access a greater surface area of the composite cathode.", "question": "What's the cathode?", "answer": "S ", "answer_start": 131}
{"document_id": 75460, "context": "For the emerging potassium-ion energy storage technology, the major challenge is seeking suitable electrode materials with a robust structure and fast kinetics for the reversible insertion/desertion of potassium ions. Here, a pseudocapacitive core\u2013shell heterostructure of titanium oxide/carbon confined into N, P, and S co-doped carbon (TiO2/C@NPSC) is obtained by pyrolyzing a metal\u2013organic framework (MOF) precursor of MIL-125 (Ti) modified by poly(cyclotriphosphazene-co-4,4\u2032-sulfonyldiphenol) polymer. The distinctive structure of TiO2/C@NPSC can effectively buffer the volume variation of TiO2 nano-grains during the charge/discharge process, increase the electron/charge transfer, provide abundant active sites, and boost the pseudocapacitive-dominated K+-storage. Consequently, the TiO2/C@NPSC anode displays superior cyclability and fast kinetics behavior. Upon integrating it with a high capacitance activated carbon cathode derived from another MOF precursor, the as-built potassium-ion hybrid capacitor achieves a high-energy density of 114 W h kg\u22121 and a power output of 21 kW kg\u22121. Moreover, in a wide working potential window of 0\u20134.2 V, the device also maintains over 91.6% of its initial capacity after 10000 cycles, showing a superior cycle stability. Our results are conducive to understanding the importance of anode-engineering for designing advanced PIHCs.", "question": "What's the cathode?", "answer": "carbon", "answer_start": 920}
{"document_id": 75460, "context": "For the emerging potassium-ion energy storage technology, the major challenge is seeking suitable electrode materials with a robust structure and fast kinetics for the reversible insertion/desertion of potassium ions. Here, a pseudocapacitive core\u2013shell heterostructure of titanium oxide/carbon confined into N, P, and S co-doped carbon (TiO2/C@NPSC) is obtained by pyrolyzing a metal\u2013organic framework (MOF) precursor of MIL-125 (Ti) modified by poly(cyclotriphosphazene-co-4,4\u2032-sulfonyldiphenol) polymer. The distinctive structure of TiO2/C@NPSC can effectively buffer the volume variation of TiO2 nano-grains during the charge/discharge process, increase the electron/charge transfer, provide abundant active sites, and boost the pseudocapacitive-dominated K+-storage. Consequently, the TiO2/C@NPSC anode displays superior cyclability and fast kinetics behavior. Upon integrating it with a high capacitance activated carbon cathode derived from another MOF precursor, the as-built potassium-ion hybrid capacitor achieves a high-energy density of 114 W h kg\u22121 and a power output of 21 kW kg\u22121. Moreover, in a wide working potential window of 0\u20134.2 V, the device also maintains over 91.6% of its initial capacity after 10000 cycles, showing a superior cycle stability. Our results are conducive to understanding the importance of anode-engineering for designing advanced PIHCs.", "question": "What's the anode?", "answer": "TiO2/C@NPSC", "answer_start": 790}
{"document_id": 75472, "context": "The ATR-IR spectra (Fig. 2 for TiO2 based photoanode and Fig. S3\u2020 for NiO based photocathode) show that the intensity of the azido stretching bands has completely disappeared after heating, while that of the alkyne is visible meaning that there are some unreacted alkyne groups in the film. On the other hand, the stretching bands of the ester groups of the crosslinking agent 3 and that of the lactam of the DPP 1 or 2 (both around 1700 cm\u22121) are still clearly visible, proving that these moieties are present on the surface of the film. This result is consistent with the presence of four alkyne groups in 3 relative to only two azides on the dyes 1 or 2. The ATR-IR spectrum of the DPP 2 grafted on the electrode was not modified after heating in the crosslinking conditions (15 min at 140 \u00b0C in orthodichlorobenzene) in absence of the cross-linker 3 (Fig. S4\u2020). This indicates that the azido groups are stable in these conditions and do not degrade upon heating at 140 \u00b0C for 15 min.", "question": "What's the cathode?", "answer": "NiO ", "answer_start": 70}
{"document_id": 75471, "context": "For the former, metal Ni and Cu are the common conductivity improvers and can be introduced into the sulfur cathode through a straightforward addition and/or interfusion. For example, Manthiram's group presented a pie-like electrode that consists of nickel foam as a \u201cfilling\u201d and an outer carbon shell as a \u201ccrust\u201d for facilitating the utilization of sulfur cathodes. Copper powder was introduced into the sulfur cathode by Jia et al. through partially replacing the sulfur contained active material with Cu during the manufacture procedure of the working electrode. Very similarly, Guo and coworkers recently reported the preparation of a CNT/graphene\u2013S\u2013Al3Ni2 cathode with a 3D network structure using 10 wt% Al3Ni2 powder to displace the CNT/graphene\u2013S active material, where the Al in the Al3Ni2 provides an efficient channel for fast electron and ion transfer in the three dimensions, especially along the vertical direction of the cathode. Furthermore, Zheng et al. demonstrated a copper-stabilized sulfur\u2013microporous carbon composite synthesized by uniformly dispersing 10% highly electronically conductive Cu nanoparticles into microporous carbon (MC), followed by wet-impregnation of S. To obtain highly dispersed Cu, commercial MC with a high surface area is first selected as the matrix and carrier. An ultrasonic-assisted multiple wetness impregnation and synchro-dry method is then applied to load 50% Cu(NO3)2 ethanol alcohol solution in MC and evaporate the solvent. This process is repeated until a certain amount of Cu(NO3)2 is added to MC. Finally, Cu nanoparticles anchored in the MC are gained by the reduction of the dry precursor at 200 \u00b0C for 1 h under an argon mixed with 5% hydrogen environment. Interestingly, the Cu content in MC can be easily adjusted by controlling the amount of Cu(NO3)2 addition via impregnation times.", "question": "What's the cathode?", "answer": "CNT/graphene\u2013S\u2013Al3Ni2", "answer_start": 641}
{"document_id": 75471, "context": "For the former, metal Ni and Cu are the common conductivity improvers and can be introduced into the sulfur cathode through a straightforward addition and/or interfusion. For example, Manthiram's group presented a pie-like electrode that consists of nickel foam as a \u201cfilling\u201d and an outer carbon shell as a \u201ccrust\u201d for facilitating the utilization of sulfur cathodes. Copper powder was introduced into the sulfur cathode by Jia et al. through partially replacing the sulfur contained active material with Cu during the manufacture procedure of the working electrode. Very similarly, Guo and coworkers recently reported the preparation of a CNT/graphene\u2013S\u2013Al3Ni2 cathode with a 3D network structure using 10 wt% Al3Ni2 powder to displace the CNT/graphene\u2013S active material, where the Al in the Al3Ni2 provides an efficient channel for fast electron and ion transfer in the three dimensions, especially along the vertical direction of the cathode. Furthermore, Zheng et al. demonstrated a copper-stabilized sulfur\u2013microporous carbon composite synthesized by uniformly dispersing 10% highly electronically conductive Cu nanoparticles into microporous carbon (MC), followed by wet-impregnation of S. To obtain highly dispersed Cu, commercial MC with a high surface area is first selected as the matrix and carrier. An ultrasonic-assisted multiple wetness impregnation and synchro-dry method is then applied to load 50% Cu(NO3)2 ethanol alcohol solution in MC and evaporate the solvent. This process is repeated until a certain amount of Cu(NO3)2 is added to MC. Finally, Cu nanoparticles anchored in the MC are gained by the reduction of the dry precursor at 200 \u00b0C for 1 h under an argon mixed with 5% hydrogen environment. Interestingly, the Cu content in MC can be easily adjusted by controlling the amount of Cu(NO3)2 addition via impregnation times.", "question": "What's the cathode?", "answer": "sulfur", "answer_start": 101}
{"document_id": 75475, "context": "At a volumetric current density of 268 mA cm\u22123, the volumetric capacity of \u223c215 mA h cm\u22123 of LixMnO2/nanomesh is much larger than the capacity of many 3D core\u2013shell cathodes at similar vol. current densities, such as MnO2-coated carbon nanotubes (\u223c53 mA h cm\u22123), LiCoO2-coated carbon fiber mats (\u223c70 mA h cm\u22123), LiCoO2-coated aluminium nanowires (\u223c140 mA h cm\u22123) or V2O5-coated CNT/PAN sheets (\u223c155 mA h cm\u22123). At a vol. current density of \u223c270 mA cm\u22123, the volumetric capacity of the nanomesh cathodes is only significantly inferior to that of LiCoO2-coated carbon foam (\u223c370 mA h cm\u22123) and Li2MnSiO4 doubly-loaded on graphene inverse opals (\u223c520 mA h cm\u22123) \u2013 both electrodes having a very high volume fraction of the active materials of 57% and 90%, respectively. Furthermore, also at high current densities above 1000 mA cm\u22123, the nanomesh cathode retains superior volumetric capacity to most of the electrodes, being only inferior to the two aforementioned electrodes and the V2O5-coated graphene inverse opals with a highly regular structure and larger pores. At high currents densities, however, the comparison may be additionally affected by the varying thicknesses of the electrodes (Table S3\u2020), since thinner electrodes (such as ours) typically show better high-rate performance.", "question": "What's the cathode?", "answer": "LixMnO2/nanomesh", "answer_start": 93}
{"document_id": 75477, "context": "Up to now, owing to the tremendous work done by different research groups, there have been several new types of electrolysers proposed for decoupled H2/O2 generation through the utilization of redox mediators, and a list of these new electrolysers has been provided in Table S1 in the ESI.\u2020 For example, a new PEM electrolyser is proposed with polyoxometalates (POMs) used as the redox relay, and the H2/O2 generation can be decoupled both in time and in space (Scheme 1b). Such a design requires three electrodes (OER electrode, carbon electrode for reduction of the soluble POM redox mediator, and Pt catalyst for spontaneous hydrogen evolution), one soluble redox mediator (POMs), one membrane (Nafion membrane) and two cells, which potentially increases the cost for the electrolysers. A solid redox mediator, such as Ni(OH)2, has also been successfully used as the relay for decoupled water splitting (Scheme 1c). This kind of design needs no separator between the cathode and the anode; however, an auxiliary relay electrode has been used and the whole cell is still a three-component system, and the overall cost for the electrolyser may not be effectively reduced. Also, among all these designs, since the HER and OER are decoupled in time, there is always an electrode (either the HER or the OER electrode) in an idle state when the cell is in operation. For decoupled water splitting in time, the integration of the HER and OER in one electrode can effectively reduce the cost and space for the electrolyser, which is more practical for scale-up applications; however, a rational design toward this direction has not been proposed.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75477, "context": "Up to now, owing to the tremendous work done by different research groups, there have been several new types of electrolysers proposed for decoupled H2/O2 generation through the utilization of redox mediators, and a list of these new electrolysers has been provided in Table S1 in the ESI.\u2020 For example, a new PEM electrolyser is proposed with polyoxometalates (POMs) used as the redox relay, and the H2/O2 generation can be decoupled both in time and in space (Scheme 1b). Such a design requires three electrodes (OER electrode, carbon electrode for reduction of the soluble POM redox mediator, and Pt catalyst for spontaneous hydrogen evolution), one soluble redox mediator (POMs), one membrane (Nafion membrane) and two cells, which potentially increases the cost for the electrolysers. A solid redox mediator, such as Ni(OH)2, has also been successfully used as the relay for decoupled water splitting (Scheme 1c). This kind of design needs no separator between the cathode and the anode; however, an auxiliary relay electrode has been used and the whole cell is still a three-component system, and the overall cost for the electrolyser may not be effectively reduced. Also, among all these designs, since the HER and OER are decoupled in time, there is always an electrode (either the HER or the OER electrode) in an idle state when the cell is in operation. For decoupled water splitting in time, the integration of the HER and OER in one electrode can effectively reduce the cost and space for the electrolyser, which is more practical for scale-up applications; however, a rational design toward this direction has not been proposed.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75478, "context": "Commercial sublimated sulfur (S) was mixed with AB (C) in a mass ratio of 8:2, and the mixture (C/S) was fully ground and heat-treated at 155 \u00b0C for 6 h in an argon atmosphere. Then, the as-obtained composite was mixed with AB and PVDF (8:1:1 by weight), followed by dispersing in NMP solvent and stirred for 12 h. Next, the slurry was uniformly cast onto an Al foil substrate and dried in a vacuum for 12 h at 60 \u00b0C. Afterwards, the coated-Al foil was cut into 12 mm wafers with a sulfur loading of \u223c2.0 mg cm\u22122. Moreover, a cathode wafer with a high sulfur loading of \u223c5.6 mg cm\u22122 was also prepared in the same procedure by controlling the thickness of the coating. The as-prepared C/S disc, above separators (BFO/GO/AB@PP, GO/AB@PP, and PP) and lithium plate (diameter of 15.6 mm, thickness of 250 \u00b5m) were applied to assemble a 2025-type button battery, in which the electrolyte was 1 M LiTFSI in DOL/DME (v/v = 1:1) with 1 wt% LiNO3. The electrolyte/sulfur (E/S) ratio was fixed as 12:1 (\u00b5L mg\u22121). The battery was charged and discharged on a Neware battery test station (5V20 mA). The cyclic voltammetry (CV) curves were operated in a voltage window between 1.7 and 2.8 V with a scanning rate of 0.1 mV s\u22121. The electrochemical impedance spectroscopy (EIS) plots were obtained in the frequency range from 0.1 to 100 kHz with an amplitude of 5 mV. Both CV and EIS were carried out on an electrochemical workstation (Shanghai, Chenhua, CHI660D).", "question": "What's the cathode?", "answer": "sulfur", "answer_start": 552}
{"document_id": 75479, "context": "Numerous studies reported core\u2013shell 3D-nanostructured Li-ion electrodes with active components such as Si, Sn, TiO2, Nb2O5, Co3O4 or iron oxides, mostly applicable as negative electrodes (anodes). On the other hand, nanostructured 3D positive electrodes (cathodes) based on active materials with a desirable high redox potential vs. Li+/Li (e.g. lithiated manganese oxides, V2O5 or LiCoO2 have been reported in comparatively fewer publications. For such cathodes, a big difficulty lies in inherent oxidation of the 3D current collector during the synthesis of high voltage cathode materials \u2013 the latter typically requiring temperatures above 700 \u00b0C. By lowering the synthesis temperature to 300 \u00b0C, Zhang et al. and Pikul et al. successfully demonstrated both core\u2013shell cathodes and full 3D Li-ion microbatteries which employed lithiated manganese oxides coated on inverse nickel opal current collectors. Impressively, the devices were operational at C-rates above 1000 (where the rate of 1C corresponds to the current required for 1 hour of a complete charge or discharge). The same group also demonstrated other high-performance 3D cathodes, such as a carbon foam coated with dense LiCoO2 or inverted opals doubly-filled with V2O5 and Li2MnSiO4. Currently, however, the electrode design based on regular inverse opal current collectors is difficult to envision for large scale battery manufacturing, as the fabrication of these current collectors is time consuming (e.g. >24 h for a 20 \u03bcm-thick structure), involves difficult to handle colloidal templates and is limited to small surfaces (\u223c1 cm2). Importantly, the application of a current collector with yet a higher volumetric surface area may allow further reducing the thickness of the active material and gaining access to its full theoretical capacity.", "question": "What's the cathode?", "answer": "a carbon foam coated with dense LiCoO2", "answer_start": 1155}
{"document_id": 75479, "context": "Numerous studies reported core\u2013shell 3D-nanostructured Li-ion electrodes with active components such as Si, Sn, TiO2, Nb2O5, Co3O4 or iron oxides, mostly applicable as negative electrodes (anodes). On the other hand, nanostructured 3D positive electrodes (cathodes) based on active materials with a desirable high redox potential vs. Li+/Li (e.g. lithiated manganese oxides, V2O5 or LiCoO2 have been reported in comparatively fewer publications. For such cathodes, a big difficulty lies in inherent oxidation of the 3D current collector during the synthesis of high voltage cathode materials \u2013 the latter typically requiring temperatures above 700 \u00b0C. By lowering the synthesis temperature to 300 \u00b0C, Zhang et al. and Pikul et al. successfully demonstrated both core\u2013shell cathodes and full 3D Li-ion microbatteries which employed lithiated manganese oxides coated on inverse nickel opal current collectors. Impressively, the devices were operational at C-rates above 1000 (where the rate of 1C corresponds to the current required for 1 hour of a complete charge or discharge). The same group also demonstrated other high-performance 3D cathodes, such as a carbon foam coated with dense LiCoO2 or inverted opals doubly-filled with V2O5 and Li2MnSiO4. Currently, however, the electrode design based on regular inverse opal current collectors is difficult to envision for large scale battery manufacturing, as the fabrication of these current collectors is time consuming (e.g. >24 h for a 20 \u03bcm-thick structure), involves difficult to handle colloidal templates and is limited to small surfaces (\u223c1 cm2). Importantly, the application of a current collector with yet a higher volumetric surface area may allow further reducing the thickness of the active material and gaining access to its full theoretical capacity.", "question": "What's the cathode?", "answer": "inverted opals doubly-filled with V2O5 and Li2MnSiO4", "answer_start": 1197}
{"document_id": 75484, "context": "In summary, we report a highly effective approach to prevent Li dendrite formation by an in situ formed self-repairing alloy layer (LixGa). During lithiation, evenly distributed Ga nanoparticles serve as lithiophilic sites to induce a homogeneous Li nucleation. Stress generated during Li plating can also be eliminated by the soft Ga nanoparticles. During the delithiation, metallic liquid Ga partially recovered from the dealloying process by timely filling the small gaps, which effectively avoided the generation of microcracks. A long-term cycling life of over 1800 h and 1400 h was obtained for the alloy-protected Li anodes at the high current densities of 2 mA cm\u22122 and 5 mA cm\u22122, respectively. Even increasing the current density and deposition capacity to 15 mA cm\u22122 and 15 mA h cm\u22122, respectively, the alloy-protected Li anodes still showed a stable cycling performance. Functionalized full cells coupled with LiFePO4 cathodes are finally cycled up to 600 cycles at 3C rate with the discharge capacity maintained at 128 mA h g\u22121. This simple and facile modification method is expected to realize the high-rate and long-life cycling of the Li metal anode and paves the way for the industrialization of Li metal batteries.", "question": "What's the cathode?", "answer": "LiFePO4 ", "answer_start": 921}
{"document_id": 75485, "context": "The rate performance of the nanomesh cathode was tested at C-rates between 1.2 and 24C (corresponding to the volumetric currents of 269 mA cm\u22123 and 5387 mA cm\u22123, respectively). For each C-rate, five discharge\u2013charge cycles were recorded, starting from the fully charged state. Therefore, we distinguish the \u201cinitial\u201d discharge capacities (recorded after fully charging the cathode at 4.0 V for 1 hour) from the \u201ccontinuous\u201d discharge capacities recorded in the four consecutive cycles, which also depend on the charging kinetics at each C-rate. The discharge\u2013charge profiles recorded in the first discharge\u2013charge cycle at each C-rate are presented in Fig. 5c. The profiles have a similar shape at all the C-rates, showing that the higher currents did not affect the mechanism of Li storage in the cathode. The initial discharge capacity at 6C was 70% of the initial discharge capacity at 1.2C. When the cathode was discharged from the fully charged state at high rates of 18C and 24C (the current required for a theoretical full discharge in \u223c3 min and 2.5 min, respectively), the initial capacity was still 50% and 45% of the initial capacity at 1.2C, demonstrating good rate performance of the cathode. The rate performance is, however, much inferior to that of LixMnO2-coated inverse Ni opals synthesisedby Zhang et al. (\u223c55% of 1.1C capacity at 743C). This is to be expected, as the mean pore size in the LixMnO2/nanomesh is about 40 nm which is significantly smaller than that in the LixMnO2/Ni opals (pore size of a few hundred nanometers). The small pore size lowers the diffusion rate of Li+ in the electrolyte within the electrode, which gradually becomes the rate-limiting factor during fast cycling of nanoporous electrodes. The differences in relative capacities of the nanomesh cathode are also amplified by the increased loss of active capacity after high rate cycling and prolonged charging at 4 V, as the initial discharge capacity at 1.2C in the 31st cycle was 73% of the initial discharge capacity at 1.2C in the first cycle (Fig. 5d).", "question": "What's the cathode?", "answer": "nanomesh ", "answer_start": 28}
{"document_id": 75492, "context": "In summary, we report novel free-standing DBHF nanofibers as a highly efficient and high-performance cathode for hybrid Zn batteries. Their unique structure with a fiber-in-tube hierarchical configuration, defect-rich crystals, carbon based network and hollow spherical basic units facilitates fast electron/ion transport and ORR/OER reaction kinetics. Benefitting from the advantages of the DBHF structure and the self-supporting character, the fabricated flexible hybrid Zn battery with the DBHF cathode achieves high operating voltage, high rate capability, high energy/power density and good adaptability under different working conditions. Furthermore, its outstanding stability and high efficiency are demonstrated by five-thousand high-rate cycling. More impressively, the excellent air charging capability makes it an outstanding power source for uninterrupted power supply while altering the working environment. Therefore, this work not only provides a novel strategy to synergistically improve the efficiency and performance of hybrid Zn batteries with both Zn-ion and Zn\u2013air modes, but also opens a new avenue to fabricate high-performance flexible batteries for different electronics under various working conditions.", "question": "What's the cathode?", "answer": "DBHF nanofibers", "answer_start": 42}
{"document_id": 75492, "context": "In summary, we report novel free-standing DBHF nanofibers as a highly efficient and high-performance cathode for hybrid Zn batteries. Their unique structure with a fiber-in-tube hierarchical configuration, defect-rich crystals, carbon based network and hollow spherical basic units facilitates fast electron/ion transport and ORR/OER reaction kinetics. Benefitting from the advantages of the DBHF structure and the self-supporting character, the fabricated flexible hybrid Zn battery with the DBHF cathode achieves high operating voltage, high rate capability, high energy/power density and good adaptability under different working conditions. Furthermore, its outstanding stability and high efficiency are demonstrated by five-thousand high-rate cycling. More impressively, the excellent air charging capability makes it an outstanding power source for uninterrupted power supply while altering the working environment. Therefore, this work not only provides a novel strategy to synergistically improve the efficiency and performance of hybrid Zn batteries with both Zn-ion and Zn\u2013air modes, but also opens a new avenue to fabricate high-performance flexible batteries for different electronics under various working conditions.", "question": "What's the cathode?", "answer": "DBHF", "answer_start": 493}
{"document_id": 75495, "context": "With the new development of electronic products and electric vehicles, state-of-the-art lithium-ion batteries are facing a grand challenge in meeting the rapidly expanding energy demand due to their inherently limited theoretical energy density. Lithium\u2013sulfur (Li\u2013S) batteries, on the other hand, shown to have five times higher theoretical specific capacity and energy density, have demonstrated tremendous potential for next-generation energy storage equipment applications. In addition, the environmental benignity and economic benefits of elemental sulfur further buttress its large-scale commercial manufacture. Despite these merits, the application of Li\u2013S batteries is still hindered by some intractable challenges: firstly, the poor resistivity of elemental sulfur will reduce the utilization of raw materials and the reaction kinetics; secondly, the excessive volume expansion (\u223c80%) during charging/discharging may result in inevitable evolution of structures and strain; and thirdly, lithium polysulfides (LiPSs) dissolved from the cathode can penetrate the separator and deposit on the anode surface, leading to the \u201cshuttle effect\u201d and anode corrosion. These issues have been the bottlenecks in the development of high-performance Li\u2013S batteries.", "question": "What's the cathode?", "answer": " lithium polysulfides (LiPSs) ", "answer_start": 995}
{"document_id": 75497, "context": "In this work, we developed lithium-ion cathodes based on 3D-interconnected Ni nanowire current collectors and a lithiated manganese oxide active material, which combine high volumetric capacity and good rate performance. The 3D-nanowire current collector exhibits high porosity and a very high surface-to-volume ratio. Consequently, upon conformally coating it with the active material, the energy-storing component is distributed over a few nanometer-thick layer. Since the Ni nanowire network provides access of electrons to the entire volume of the active material and the ionic transport in the thin active layer is unimpeded, the cathode reached very high utilization of the active material, which is typically inaccessible in bulk cathodes. As a result, the electrode exhibits a high rechargeable volumetric capacity of about 200 mA h cm\u22123, which is more than the capacity of most 3D-nanostructured cathodes reported in the literature. Additionally, thanks to the combination of the small thickness of the active material and its high contact area with the current collector and electrolyte, the cathode can deliver significantly high capacity during high rate charging and discharging, demonstrating its potential for use in high volumetric capacity and fast charging Li-ion batteries.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75498, "context": "LLZO pellets were sputter-coated (LEICA EM ACE600) with Au on both sides to form contacts that acted as Li ion quasi-blocking electrodes. In order to fabricate Li symmetric cells, LLZO pellets were sandwiched between two Li metal discs (Sigma Aldrich) either with or without interposition of IL interlayers. 5 \u03bcL of the gel electrolytes were introduced at each interface. Cells without the interlayer were heated till 180 \u00b0C (melting temperature of Li) to promote Li\u2013SE mutual contact. Both Au|LLZO|Au and Li|LLZO|Li were assembled in Swagelok\u00a9-type cell holders. Electrochemical impedance spectroscopy (EIS) was performed using an electrochemical workstation (ZAHNER-Elektrik GmbH) with an applied sinusoidal excitation voltage of 10 mV in the frequency range from 5 MHz to 0.01 Hz. EIS data were fitted with ZView software. A Bio-Logic VMP-3 potentiostat was used to conduct the Li stripping and plating tests at current densities ranging from 0.05 to 0.4 mA cm\u22122. The cathode slurry was prepared by mixing S/NC powders (90 wt%) and the PVDF binder (10 wt%, Kynar) by magnetic stirring using NMP as solvent. The obtained slurry was cast onto aluminum foil by doctor blade techniques and thereafter dried at 60 \u00b0C for 24 h. The sulfur loading at the electrode was \u223c0.5 mgsulfur cm\u22122. The electrochemical performance of the full cells was tested by galvanostatic cycling with 0.1C (1C = 1672 mA gsulfur\u22121) in the voltage range between 3 and 1.5 V, using an Arbin BT-2000 battery tester at room temperature. The preparation of the cells and all electrochemical tests were performed in an argon-filled glove-box.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75505, "context": "For more than a decade, researchers have known that layered oxide cathodes, particularly NMC and NCA materials, have fragile surfaces. Thus, it allows various chemical/electrochemical reactions with gases (e.g., storing environments) or liquids (e.g., organic electrolytes) at the surfaces. As the urgent demand for commercialization of the Co-free, Ni-rich layered cathodes, the shelf life of active powders is considered as an important characteristic due to the uncertain delay from powder production to electrode processing and to battery manufacturing. In addition, with the nickel concentration approaching 100%, and the pursuit towards Co-free materials, surface stability against the organic electrolyte is vital in the commercialization. LiNiO2-based materials are more unstable than their cobalt-containing analogs because of the increased magnetic frustration of Ni3+ than Co3+. Therefore, surface degradation is more severe in Ni-rich oxide cathodes due to the high oxidation state of nickel. We previously discovered that the electrochemical performance of LiNiO2 cathode can be improved by incorporating dual dopants through the surface and bulk properties enhancement. Herein, we exploit the platform of LiNiO2-based materials to study the surface fragility under various practical conditions. Moreover, we will further discuss advantages of doping chemistry through the post-mortem characterizations. Lastly, we are aiming to provide insights into developing low-cost, high-energy Co-free Ni-rich cathode materials.", "question": "What's the cathode?", "answer": "LiNiO2 ", "answer_start": 1070}
{"document_id": 75505, "context": "For more than a decade, researchers have known that layered oxide cathodes, particularly NMC and NCA materials, have fragile surfaces. Thus, it allows various chemical/electrochemical reactions with gases (e.g., storing environments) or liquids (e.g., organic electrolytes) at the surfaces. As the urgent demand for commercialization of the Co-free, Ni-rich layered cathodes, the shelf life of active powders is considered as an important characteristic due to the uncertain delay from powder production to electrode processing and to battery manufacturing. In addition, with the nickel concentration approaching 100%, and the pursuit towards Co-free materials, surface stability against the organic electrolyte is vital in the commercialization. LiNiO2-based materials are more unstable than their cobalt-containing analogs because of the increased magnetic frustration of Ni3+ than Co3+. Therefore, surface degradation is more severe in Ni-rich oxide cathodes due to the high oxidation state of nickel. We previously discovered that the electrochemical performance of LiNiO2 cathode can be improved by incorporating dual dopants through the surface and bulk properties enhancement. Herein, we exploit the platform of LiNiO2-based materials to study the surface fragility under various practical conditions. Moreover, we will further discuss advantages of doping chemistry through the post-mortem characterizations. Lastly, we are aiming to provide insights into developing low-cost, high-energy Co-free Ni-rich cathode materials.", "question": "What's the cathode?", "answer": "Ni-rich oxide", "answer_start": 939}
{"document_id": 75507, "context": "Although decomposition is unavoidable, lithium residuals do not negatively impact capacity decay, resulting in similar capacity retentions of 73.7%, 70.1%, and 68.7% for the samples aged in the Ar glovebox, in the dry box, and in the fresh state, respectively (Fig. 2b). According to many studies, surface contaminants increase the ion diffusion energy barrier and promote increased amounts of gas generation (i.e. CO2), which ultimately contributes to battery volume expansion. Degassing process after formation cycles is commonly adopted before the battery sealing, which adds to the battery cost. Thus, washing cathode powders using water, alcohol, or other solvents, or a simple high temperature annealing under oxygen flow can be utilized to remove the lithium residues. We also noticed that upon extensive storage (three months in the dry box), the large amount of carbonates can be visible in the SEM (scanning electron microscopy) images, which would more negatively impact the battery performance (Fig. S3\u2020). Given that these materials are sensitive to storage environment and duration, it is recommended that scientific publications should specify these details when the performance is reported.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75509, "context": "The electrode pastes were composed of active materials/carbon black/gel electrolyte precursor whose composition ratios were 60/8.5/31.5 (w/w/w) for the LiCoO2 (LCO) cathode and 52/7.5/40.5 (w/w/w) for the Li4Ti5O12 (LTO) anode, respectively. The gel polymer electrolyte precursor was prepared by mixing a UV-curable ethoxylated trimethylolpropane tri-acrylate (ETPTA) monomer (Aldrich) (including 1.0 wt% 2-hydroxy-2-methl-1-phenyl-1-1propanone (HMPP) as a photo-initiator) and high boiling point electrolyte (1 M LiPF6 in ethylene carbonate(EC)/propylene carbonate(PC) 1/1 (v/v)) in a composition ratio of 15/85 (w/w). To fabricate the bQSSB with cSiPV, the LTO anode paste was directly stencil-printed onto an Al current collector of the cSiPV module without any processing solvents and then exposed to UV irradiation. UV irradiation was performed using an Hg UV-lamp (Lichtzen) with an irradiation peak intensity of approximately 1260 mW cm\u22122. Subsequently, on the LTO anode (thickness = 50 \u03bcm and mass loading = 5.9 mg cm\u22122), a composite polymer electrolyte (CPE, gel electrolyte precursor/Al2O3 nanoparticles (average particle size \u223c300 nm) = 56/44 (w/w)) was introduced through the UV curing-assisted printing process. Then, the LCO cathode paste was stencil-printed directly on the CPE/LTO anode and solidified by UV irradiation, yielding the printed LCO cathode (thickness = 30 \u03bcm and mass loading = 6.2 mg cm\u22122). After placing an Al current collector on top of the printed LCO cathode/printed CPE/printed LTO anode, the QSSB unit cell was obtained. Another QSSB unit cell was introduced, using the same printing process, on the top of the pre-fabricated QSSB unit cell, leading to the bQSSB with a bipolar structure. The number of QSSB unit cells on the cSiPV module was determined from the Vmax of the module concerning the voltage matching between the cSiPV and the bQSSB. Finally, the encapsulation of the bQSSB was conducted with Al pouch packaging substances and a UV-curable hydrophobic polymer (PRO-001, Novacentrix). All assembly steps of the cells were performed in a dry room.", "question": "What's the cathode?", "answer": " LiCoO2 (LCO) ", "answer_start": 151}
{"document_id": 75509, "context": "The electrode pastes were composed of active materials/carbon black/gel electrolyte precursor whose composition ratios were 60/8.5/31.5 (w/w/w) for the LiCoO2 (LCO) cathode and 52/7.5/40.5 (w/w/w) for the Li4Ti5O12 (LTO) anode, respectively. The gel polymer electrolyte precursor was prepared by mixing a UV-curable ethoxylated trimethylolpropane tri-acrylate (ETPTA) monomer (Aldrich) (including 1.0 wt% 2-hydroxy-2-methl-1-phenyl-1-1propanone (HMPP) as a photo-initiator) and high boiling point electrolyte (1 M LiPF6 in ethylene carbonate(EC)/propylene carbonate(PC) 1/1 (v/v)) in a composition ratio of 15/85 (w/w). To fabricate the bQSSB with cSiPV, the LTO anode paste was directly stencil-printed onto an Al current collector of the cSiPV module without any processing solvents and then exposed to UV irradiation. UV irradiation was performed using an Hg UV-lamp (Lichtzen) with an irradiation peak intensity of approximately 1260 mW cm\u22122. Subsequently, on the LTO anode (thickness = 50 \u03bcm and mass loading = 5.9 mg cm\u22122), a composite polymer electrolyte (CPE, gel electrolyte precursor/Al2O3 nanoparticles (average particle size \u223c300 nm) = 56/44 (w/w)) was introduced through the UV curing-assisted printing process. Then, the LCO cathode paste was stencil-printed directly on the CPE/LTO anode and solidified by UV irradiation, yielding the printed LCO cathode (thickness = 30 \u03bcm and mass loading = 6.2 mg cm\u22122). After placing an Al current collector on top of the printed LCO cathode/printed CPE/printed LTO anode, the QSSB unit cell was obtained. Another QSSB unit cell was introduced, using the same printing process, on the top of the pre-fabricated QSSB unit cell, leading to the bQSSB with a bipolar structure. The number of QSSB unit cells on the cSiPV module was determined from the Vmax of the module concerning the voltage matching between the cSiPV and the bQSSB. Finally, the encapsulation of the bQSSB was conducted with Al pouch packaging substances and a UV-curable hydrophobic polymer (PRO-001, Novacentrix). All assembly steps of the cells were performed in a dry room.", "question": "What's the cathode?", "answer": "LCO", "answer_start": 1235}
{"document_id": 75510, "context": "In comparison with well-protected rigid batteries with liquid electrolytes, solid-state batteries (ssBs) are more beneficial, offering high flexibility, high wearability and leakage prevention. Currently, ssBs with the capability of bending and twisting have been extensively studied. However, it remains a challenge to develop a highly stretchable ssB with the maintenance of high performance. Herein, we report a stable solid-state zinc ion battery (ssZIB) based on a cellulose nanofiber (CNF)\u2013polyacrylamide (PAM) hydrogel electrolyte and a Mg0.23V2O5\u00b71.0H2O cathode. The designed CNF\u2013PAM hydrogel shows high stretchability and robust mechanical stability. Moreover, the porous CNF\u2013PAM hydrogel electrolyte provides efficient pathways for the transportation of zinc ions. And the robust layered structure of V2O5\u00b71.0H2O pillared with Mg2+ ions and water supports the fast insertion/extraction of zinc ions in the lattice. Therefore, the designed ssZIB shows unprecedented high capacity at high current with durable cycling life. At a current density of 5 A g\u22121 (charging time of around 3 minutes), the ssZIBs can deliver a high reversible capacity of 216 mA h g\u22121 after 2000 cycles and retain 98.6% of the initial capacity, showing a high capacity and long-life durability at high currents. Furthermore, the designed spring ssZIBs can work under stretching with the strain reaching 650%. And the designed ssZIBs are still operational even under repeated bending, freezing, and heating conditions. The ssZIBs show robust mechanical stability, high stretchability and impressive electrochemical performance, providing a potential pathway to expand the application of ZIBs to a broad range of practical energy storage devices.", "question": "What's the cathode?", "answer": "Mg0.23V2O5\u00b71.0H2O", "answer_start": 544}
{"document_id": 75524, "context": "To investigate the electrochemical Na ion storage mechanism to predict the theoretical properties of Nax[Ni0.5Mn0.5]O2, we performed first-principles calculations based on the structural information verified through the Rietveld refinement analysis. At this stage, even though 0.01 mol of Ca2+ ions was incorporated into the bulk Na sites, Na0.98Ca0.01[Ni0.5Mn0.5]O2 showed a nearly identical crystal structure with Na[Ni0.5Mn0.5]O2; hence, we assumed that Na0.98Ca0.01[Ni0.5Mn0.5]O2 experienced the same O3\u2013P3 phase transformation during the Na+ extraction/insertion process. Various Na/vacancy configurations on O3-Nax[Ni0.5Mn0.5]O2 compositions (0 \u2264 x \u2264 1) were generated through the cluster assisted statistical mechanics (CASM) code and then, we predicted the theoretical formation energies of the O3-Nax[Ni0.5Mn0.5]O2 composition. Based on information of the formation energies, we calculated the redox potentials of O3-Nax[Ni0.5Mn0.5]O2 during Na+ extraction/insertion using the following equation where E(x) indicates the formation energy on the most stable Na/vacancy configuration of x species. By considering the typical O3\u2013P3 phase transition in the O3-type layered oxide cathode in SIBs, we calculated the formation energies of P3-Nax[Ni0.5Mn0.5]O2 and then applied this information to compare the thermodynamic stability between O3- and P3-phases. As presented in Fig. 4a, we predicted that the O3\u2013P3 phase transition occurred after extraction of 0.25 mol of Na ions from O3-Na1[Ni0.5Mn0.5]O2, and then, when the Na content in P3-Nax[Ni0.5Mn0.5]O2 was reduced to less than 0.25 mol, the O3\u2013P3 phase transition re-occurred. Moreover, we verified that in the case of O3-/P3-Nax[Ni0.5Mn0.5]O2, the redox potentials required for Na+ extraction/insertion were less than \u223c4.11 V (vs. Na+/Na) and more than \u223c2.48 V, which indicates that 1 mol of Na ions can be reversibly extracted/inserted from/into the O3-Na1[Ni0.5Mn0.5]O2 structure despite the O3\u2013P3 phase transition. Fig. 4b illustrates the predicted redox potential range of the O3/P3-Nax[Ni0.5Mn0.5]O2 cathode as a function of the Na content (0 \u2264 x \u2264 1) with experimentally measured galvanostatic intermittent titration technique (GITT) profiles in the voltage range of 2.0\u20134.3 V. To confirm our hypothesis that the Ca-substituted cathode would undergo a similar O3\u2013P3 phase transformation during the sodiation/de-sodiation process, we checked the GITT profiles of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode and overlaid the results with the predicted theoretical redox potential of the Nax[Ni0.5Mn0.5]O2 cathode. Interestingly, we confirmed that the slope of the charge/discharge curve of O3-Na0.98Ca0.01[Ni0.5Mn0.5]O2 matched the predicted redox potential of the Nax[Ni0.5Mn0.5]O2 cathode well within the wide voltage window of 2.0\u20134.3 V; this clearly verified our hypothesis and confirmed that \u223c1.0 mol of Na+ ions could be extracted/inserted from/into Na0.98Ca0.01[Ni0.5Mn0.5]O2.", "question": "What's the cathode?", "answer": "O3-type layered oxide", "answer_start": 1162}
{"document_id": 75524, "context": "To investigate the electrochemical Na ion storage mechanism to predict the theoretical properties of Nax[Ni0.5Mn0.5]O2, we performed first-principles calculations based on the structural information verified through the Rietveld refinement analysis. At this stage, even though 0.01 mol of Ca2+ ions was incorporated into the bulk Na sites, Na0.98Ca0.01[Ni0.5Mn0.5]O2 showed a nearly identical crystal structure with Na[Ni0.5Mn0.5]O2; hence, we assumed that Na0.98Ca0.01[Ni0.5Mn0.5]O2 experienced the same O3\u2013P3 phase transformation during the Na+ extraction/insertion process. Various Na/vacancy configurations on O3-Nax[Ni0.5Mn0.5]O2 compositions (0 \u2264 x \u2264 1) were generated through the cluster assisted statistical mechanics (CASM) code and then, we predicted the theoretical formation energies of the O3-Nax[Ni0.5Mn0.5]O2 composition. Based on information of the formation energies, we calculated the redox potentials of O3-Nax[Ni0.5Mn0.5]O2 during Na+ extraction/insertion using the following equation where E(x) indicates the formation energy on the most stable Na/vacancy configuration of x species. By considering the typical O3\u2013P3 phase transition in the O3-type layered oxide cathode in SIBs, we calculated the formation energies of P3-Nax[Ni0.5Mn0.5]O2 and then applied this information to compare the thermodynamic stability between O3- and P3-phases. As presented in Fig. 4a, we predicted that the O3\u2013P3 phase transition occurred after extraction of 0.25 mol of Na ions from O3-Na1[Ni0.5Mn0.5]O2, and then, when the Na content in P3-Nax[Ni0.5Mn0.5]O2 was reduced to less than 0.25 mol, the O3\u2013P3 phase transition re-occurred. Moreover, we verified that in the case of O3-/P3-Nax[Ni0.5Mn0.5]O2, the redox potentials required for Na+ extraction/insertion were less than \u223c4.11 V (vs. Na+/Na) and more than \u223c2.48 V, which indicates that 1 mol of Na ions can be reversibly extracted/inserted from/into the O3-Na1[Ni0.5Mn0.5]O2 structure despite the O3\u2013P3 phase transition. Fig. 4b illustrates the predicted redox potential range of the O3/P3-Nax[Ni0.5Mn0.5]O2 cathode as a function of the Na content (0 \u2264 x \u2264 1) with experimentally measured galvanostatic intermittent titration technique (GITT) profiles in the voltage range of 2.0\u20134.3 V. To confirm our hypothesis that the Ca-substituted cathode would undergo a similar O3\u2013P3 phase transformation during the sodiation/de-sodiation process, we checked the GITT profiles of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode and overlaid the results with the predicted theoretical redox potential of the Nax[Ni0.5Mn0.5]O2 cathode. Interestingly, we confirmed that the slope of the charge/discharge curve of O3-Na0.98Ca0.01[Ni0.5Mn0.5]O2 matched the predicted redox potential of the Nax[Ni0.5Mn0.5]O2 cathode well within the wide voltage window of 2.0\u20134.3 V; this clearly verified our hypothesis and confirmed that \u223c1.0 mol of Na+ ions could be extracted/inserted from/into Na0.98Ca0.01[Ni0.5Mn0.5]O2.", "question": "What's the cathode?", "answer": "O3/P3-Nax[Ni0.5Mn0.5]O2", "answer_start": 2042}
{"document_id": 75511, "context": "Another critical property of an electrode material toward practical application is the ease of handling against a moist environment. Most of the O3-type transition metal oxide cathodes reported so far are moisture sensitive because of the low redox potential associated with 3d-metals. Once the cathode is exposed to air or moisture, water oxidizes the transition metal ions with the concomitant removal of Na+ ions, which further react with CO2 and H2O in air to form Na2CO3 or NaOH. Such undesirable reactions usually cause structural degradation and poor electrochemical performances and thus make them difficult to handle. As revealed in Fig. 7, after exposure to air with a relative humidity of \u224855%, the Na[Ni0.5Mn0.5]O2 exhibited an apparent structural change to a Na-deficient monoclinic O\u20323 phase together with formation of Na2CO3\u00b7nH2O on the surface. In contrast, Na0.98Ca0.01[Ni0.5Mn0.5]O2 remarkably retarded spontaneous phase transition and retained the original O3 structure. To confirm in detail the structural stability against a humid atmosphere, a comparative study of the XRD evolution of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 and Na[Ni0.5Mn0.5]O2 cathodes was conducted as a function of exposure time (1, 3, and 5 days and 1 week) (Fig. S16\u2020). After 1 day, there were no significant structural changes in either cathode. However, after three days, the Na[Ni0.5Mn0.5]O2 cathode was readily oxidized in the presence of moisture, and subsequently, the intensity of (003)hex. and (104)hex. peaks decreased in the XRD patterns. After 5 days, splitting of the (003)hex. and (006)hex. diffraction lines was observed, indicating a slightly enlarged interslab distance for the new monoclinic O3 phase. Finally, after 1 week, the phase transformation from the hexagonal O3 to the monoclinic O\u20323 phase occurred in the Na[Ni0.5Mn0.5]O2 cathode. This monoclinic O\u20323 phase transformation can be observed in the sodium deficient structure when the sodium ions are extracted down to 20 mol% in the original O3 structure. In contrast, throughout the week, the intensified peaks, (003)hex., (006)hex., (101)hex., (102)hex., and (104)hex., in the O3 phase were well retained persistently for the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode, indicating less reactivity against moisture. These results suggest that the Ca2+ ions on the Na sites with strong Ca\u2013O bonding prevent the removal of Na+ ions from the structure when exposed to air. As expected, in Fig. S17,\u2020 the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode demonstrated higher reversible capacity with lower voltage polarization and better cycling stability after prolonged exposure, while the Na[Ni0.5Mn0.5]O2 cathode showed poor electrochemical performance and even exhibited an irreversible reaction during charging, due to the decomposition of Na2CO3 which is a by-product of removed Na+ ions and CO2 in air. Such a comparison of the thermal properties and air-stability strengthens the merits of Ca-substituted cathodes in practical application.", "question": "What's the cathode?", "answer": "Na0.98Ca0.01[Ni0.5Mn0.5]O2 and Na[Ni0.5Mn0.5]O2", "answer_start": 1112}
{"document_id": 75511, "context": "Another critical property of an electrode material toward practical application is the ease of handling against a moist environment. Most of the O3-type transition metal oxide cathodes reported so far are moisture sensitive because of the low redox potential associated with 3d-metals. Once the cathode is exposed to air or moisture, water oxidizes the transition metal ions with the concomitant removal of Na+ ions, which further react with CO2 and H2O in air to form Na2CO3 or NaOH. Such undesirable reactions usually cause structural degradation and poor electrochemical performances and thus make them difficult to handle. As revealed in Fig. 7, after exposure to air with a relative humidity of \u224855%, the Na[Ni0.5Mn0.5]O2 exhibited an apparent structural change to a Na-deficient monoclinic O\u20323 phase together with formation of Na2CO3\u00b7nH2O on the surface. In contrast, Na0.98Ca0.01[Ni0.5Mn0.5]O2 remarkably retarded spontaneous phase transition and retained the original O3 structure. To confirm in detail the structural stability against a humid atmosphere, a comparative study of the XRD evolution of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 and Na[Ni0.5Mn0.5]O2 cathodes was conducted as a function of exposure time (1, 3, and 5 days and 1 week) (Fig. S16\u2020). After 1 day, there were no significant structural changes in either cathode. However, after three days, the Na[Ni0.5Mn0.5]O2 cathode was readily oxidized in the presence of moisture, and subsequently, the intensity of (003)hex. and (104)hex. peaks decreased in the XRD patterns. After 5 days, splitting of the (003)hex. and (006)hex. diffraction lines was observed, indicating a slightly enlarged interslab distance for the new monoclinic O3 phase. Finally, after 1 week, the phase transformation from the hexagonal O3 to the monoclinic O\u20323 phase occurred in the Na[Ni0.5Mn0.5]O2 cathode. This monoclinic O\u20323 phase transformation can be observed in the sodium deficient structure when the sodium ions are extracted down to 20 mol% in the original O3 structure. In contrast, throughout the week, the intensified peaks, (003)hex., (006)hex., (101)hex., (102)hex., and (104)hex., in the O3 phase were well retained persistently for the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode, indicating less reactivity against moisture. These results suggest that the Ca2+ ions on the Na sites with strong Ca\u2013O bonding prevent the removal of Na+ ions from the structure when exposed to air. As expected, in Fig. S17,\u2020 the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode demonstrated higher reversible capacity with lower voltage polarization and better cycling stability after prolonged exposure, while the Na[Ni0.5Mn0.5]O2 cathode showed poor electrochemical performance and even exhibited an irreversible reaction during charging, due to the decomposition of Na2CO3 which is a by-product of removed Na+ ions and CO2 in air. Such a comparison of the thermal properties and air-stability strengthens the merits of Ca-substituted cathodes in practical application.", "question": "What's the cathode?", "answer": "Na[Ni0.5Mn0.5]O2 ", "answer_start": 1820}
{"document_id": 75522, "context": "Unlike DC voltage exfoliation, square-wave voltage uses bulk antimony, bismuth and their compounds as the anode and platinum wire or foil as the cathode, and changes the voltage direction to perform electrochemical exfoliation in an electrolytic solution of Na2SO4 or Li2SO4. This process mainly uses oxygen-containing free radicals produced by electrolysed water to assault large pieces of antimony or bismuth or their compounds in the anode, and SO42\u2212 intercalates into the interlayer. Subsequently, the gas generated between the layers of the bulk layered material further expands, and finally 2D antimony or bismuth or its compound is obtained in the electrolyte. In 2020, Marzo et al. elucidated the possible mechanism of changing the voltage exfoliation of 2D Sb and Sb2Te3. As shown in Fig. 4b, this exfoliation process comprises four different stages. In the first stage, oxygen-containing free radicals produced by the electrolysis of water on the anode bulk 2D material react with the edges and boundaries, creating bumps, cracks and holes in the bulk 2D material. Next, the small cations (H+, Li+ and Na+) intercalate into the gaps and holes formed in the previous bulk 2D material, initializing a slight and preliminary expansion of the 2D sandwich. When the conversion voltage is \u22125 V, the SO42\u2212 intercalation layer enters the interlayer of the bulk 2D material. Finally, the gases (H2, O2 and SO2 formed in these redox processes) generated by the insertion of ions between the 2D bulk material layers promote the exfoliation of the 2D material and disperses it into the electrolyte (Fig. 4b).", "question": "What's the cathode?", "answer": " platinum wire or foil", "answer_start": 115}
{"document_id": 75522, "context": "Unlike DC voltage exfoliation, square-wave voltage uses bulk antimony, bismuth and their compounds as the anode and platinum wire or foil as the cathode, and changes the voltage direction to perform electrochemical exfoliation in an electrolytic solution of Na2SO4 or Li2SO4. This process mainly uses oxygen-containing free radicals produced by electrolysed water to assault large pieces of antimony or bismuth or their compounds in the anode, and SO42\u2212 intercalates into the interlayer. Subsequently, the gas generated between the layers of the bulk layered material further expands, and finally 2D antimony or bismuth or its compound is obtained in the electrolyte. In 2020, Marzo et al. elucidated the possible mechanism of changing the voltage exfoliation of 2D Sb and Sb2Te3. As shown in Fig. 4b, this exfoliation process comprises four different stages. In the first stage, oxygen-containing free radicals produced by the electrolysis of water on the anode bulk 2D material react with the edges and boundaries, creating bumps, cracks and holes in the bulk 2D material. Next, the small cations (H+, Li+ and Na+) intercalate into the gaps and holes formed in the previous bulk 2D material, initializing a slight and preliminary expansion of the 2D sandwich. When the conversion voltage is \u22125 V, the SO42\u2212 intercalation layer enters the interlayer of the bulk 2D material. Finally, the gases (H2, O2 and SO2 formed in these redox processes) generated by the insertion of ions between the 2D bulk material layers promote the exfoliation of the 2D material and disperses it into the electrolyte (Fig. 4b).", "question": "What's the anode?", "answer": " bulk antimony, bismuth and their compounds", "answer_start": 55}
{"document_id": 75519, "context": "The development of high-capacity rechargeable lithium\u2013sulfur batteries is an ongoing challenge because of the shuttle effect, which causes rapid capacity fade, limited rate capability, and slow kinetics. Herein, conductive hollow cobalt nitride/carbon (Co5.47Nx\u2013C) spheres with nitrogen vacancies are developed as a high-performance cathode material for use in lithium\u2013sulfur batteries. Nitrogen vacancies are formed by annealing a zeolite imidazole framework (ZIF-67) precursor in ammonia. Benefiting from its Co\u2013N bonds and nitrogen-vacancy sites, the Co5.47Nx\u2013C composite achieves strong anchoring of polysulfides, fast polysulfide conversion, and accelerated lithium-ion transport. The strong anchoring effect of Co5.47Nx is confirmed by experimental measurements and density functional theory (DFT) calculations. Because of its high conductivity and nitrogen vacancies, the Co5.47Nx cathode exhibits faster redox reaction kinetics and lower polarization than a Co5.47N cathode without nitrogen vacancies, thus realizing promising rate and cycling performance. The optimized Co5.47Nx\u2013C electrode delivers a capacity of 850 mA h g\u22121 at 0.5C and a rate performance of 320 mA h g\u22121 at 10C. This high-performance, high-rate lithium\u2013sulfur battery is promising for widespread application in electric vehicles and intelligent devices.", "question": "What's the cathode?", "answer": "Co5.47Nx", "answer_start": 879}
{"document_id": 75519, "context": "The development of high-capacity rechargeable lithium\u2013sulfur batteries is an ongoing challenge because of the shuttle effect, which causes rapid capacity fade, limited rate capability, and slow kinetics. Herein, conductive hollow cobalt nitride/carbon (Co5.47Nx\u2013C) spheres with nitrogen vacancies are developed as a high-performance cathode material for use in lithium\u2013sulfur batteries. Nitrogen vacancies are formed by annealing a zeolite imidazole framework (ZIF-67) precursor in ammonia. Benefiting from its Co\u2013N bonds and nitrogen-vacancy sites, the Co5.47Nx\u2013C composite achieves strong anchoring of polysulfides, fast polysulfide conversion, and accelerated lithium-ion transport. The strong anchoring effect of Co5.47Nx is confirmed by experimental measurements and density functional theory (DFT) calculations. Because of its high conductivity and nitrogen vacancies, the Co5.47Nx cathode exhibits faster redox reaction kinetics and lower polarization than a Co5.47N cathode without nitrogen vacancies, thus realizing promising rate and cycling performance. The optimized Co5.47Nx\u2013C electrode delivers a capacity of 850 mA h g\u22121 at 0.5C and a rate performance of 320 mA h g\u22121 at 10C. This high-performance, high-rate lithium\u2013sulfur battery is promising for widespread application in electric vehicles and intelligent devices.", "question": "What's the cathode?", "answer": "Co5.47N", "answer_start": 966}
{"document_id": 75523, "context": "The carefully designed combination of TM-ions and non-TM-ions suppressed the occurrences of phase transformations during electrochemical cycling in Na \u2018half\u2019 cells. More importantly, in addition to air-cum-water stability, Ti-substitution for Mn-ions was found to drastically improve the cyclic stability, with the completely Ti-substituted Na-TM-oxide exhibiting an excellent first cycle reversible capacity of \u223c140 mA h g\u22121 (within 2.0\u20134.0 V, at C/5), negligible voltage hysteresis and a capacity retention of \u223c80% after 100 cycles. In the presence of Mn-ions, formation of Mn3+ at the particle surfaces, concomitant dissolution of Mn-ions (upon disproportionation) in electrolyte, steep rise in cathode/cell impedance and associated rapid increase in voltage hysteresis upon cycling were found to be the major causes for rapid capacity fading, which were suppressed/eliminated upon partial/complete Ti-substitution. The incorporation of functionalized MWCNTs, via simple physical mixing with the cathode-active particles, further improved the capacity retentions to \u223c87% after 100 cycles and \u223c75% after 200 cycles, along with bestowing excellent rate capability, viz., capacities at 2C and 5C being \u223c65% and \u223c50% of capacity at C/10, respectively.", "question": "What's the cathode?", "answer": "MWCNTs", "answer_start": 955}
{"document_id": 75557, "context": "Sodium-ion batteries (SIBs) have recently attracted increasing attention as an alternative to lithium-ion batteries, especially for large-scale energy storage in light of the low cost and high abundance of Na resources. Layer structured sodium transition metal oxides are an important group of cathode materials for SIBs due to their high theoretical capacities. However, the poor cycling stability at high voltage hinders their practical applications, which is due to the multiple phase transition induced structural instability. Our recent work reveals that phase transition induced cracking is a major cause of the performance decay for layered cathodes. Bulk elemental doping has been demonstrated to be an effective approach to improve the cycling performance, because doping can effectively suppress phase transition induced volume changes and even realize a zero-strain cathode or phase transition free cathode. Furthermore, dopants can act as pillars to prevent the layered structure from collapsing and they can tailor the plane spacing to achieve superior diffusion kinetics of alkaline ions.", "question": "What's the cathode?", "answer": "Layer structured sodium transition metal oxides", "answer_start": 220}
{"document_id": 75582, "context": "Polymers. Using polymeric analogs of small molecules might be an effective strategy to circumvent the solubility issue of organic redox-active materials. The first polymeric cathode material for potassium batteries was poly(anthraquinonyl sulfide) (PAQS, P1). With an ether-based electrolyte (0.5 M KTFSI in DME:DOL) it showed a reversible Qm of 200 mA h g\u22121 at 20 mA g\u22121. A capacity fading of 25% was observed after 50 cycles, while the cyclability with a carbonate-based electrolyte was inferior.", "question": "What's the cathode?", "answer": "polymeric ", "answer_start": 164}
{"document_id": 75582, "context": "Polymers. Using polymeric analogs of small molecules might be an effective strategy to circumvent the solubility issue of organic redox-active materials. The first polymeric cathode material for potassium batteries was poly(anthraquinonyl sulfide) (PAQS, P1). With an ether-based electrolyte (0.5 M KTFSI in DME:DOL) it showed a reversible Qm of 200 mA h g\u22121 at 20 mA g\u22121. A capacity fading of 25% was observed after 50 cycles, while the cyclability with a carbonate-based electrolyte was inferior.", "question": "What's the electrolyte?", "answer": "(0.5 M KTFSI in DME:DOL)", "answer_start": 292}
{"document_id": 75533, "context": "Electrospun CNFs/Nb2O5 composite nanofibers were prepared by electrospinning a solution containing the precursors of Nb(C2O4H)5, PAN and TEOS, followed by carbonization and SiO2-etching.Fig. 7f and g show the structural features of the prepared CNFs/Nb2O5 nanocomposites, which reveal a continuous mesoporous network architecture. Compared with solid CNFs/Nb2O5 composites without using TEOS in spinnable solution and bulk C/Nb2O5 prepared via directly annealing the Nb(C2O4H)5, the mesoporous CNFs/Nb2O5 composites revealed much superior electrochemical reactivity. In detail, the mesoporous Nb2O5/CNF showed outstanding cyclability (94% retention after 10000 cycles at 100C, 1C = 200 mA g\u22121), and superior rate capability with specific capacities of 287 mA h g\u22121 at 0.5C and 172 mA h g\u22121 at 150C, which was much higher than that of pure CNFs (159.1 mA h g\u22121 at 0.5C and 64.9 mA h g\u22121 at 100C). In addition, a hybrid Na-ion capacitor was fabricated by employing mesoporous CNFs/Nb2O5 as the anode and CNFs/graphene as the cathode. This device showed both large energy densities (124 W h kg\u22121, 11.2 mW h cm\u22123) and impressive power densities (60 kW kg\u22121, 5.4 W h cm\u22123), indicating that both the introducing of Nb2O5 and the unique continuous mesoporous network architecture played a crucial role in the enhancement of the electrochemical properties.", "question": "What's the cathode?", "answer": " CNFs/graphene", "answer_start": 1001}
{"document_id": 75533, "context": "Electrospun CNFs/Nb2O5 composite nanofibers were prepared by electrospinning a solution containing the precursors of Nb(C2O4H)5, PAN and TEOS, followed by carbonization and SiO2-etching.Fig. 7f and g show the structural features of the prepared CNFs/Nb2O5 nanocomposites, which reveal a continuous mesoporous network architecture. Compared with solid CNFs/Nb2O5 composites without using TEOS in spinnable solution and bulk C/Nb2O5 prepared via directly annealing the Nb(C2O4H)5, the mesoporous CNFs/Nb2O5 composites revealed much superior electrochemical reactivity. In detail, the mesoporous Nb2O5/CNF showed outstanding cyclability (94% retention after 10000 cycles at 100C, 1C = 200 mA g\u22121), and superior rate capability with specific capacities of 287 mA h g\u22121 at 0.5C and 172 mA h g\u22121 at 150C, which was much higher than that of pure CNFs (159.1 mA h g\u22121 at 0.5C and 64.9 mA h g\u22121 at 100C). In addition, a hybrid Na-ion capacitor was fabricated by employing mesoporous CNFs/Nb2O5 as the anode and CNFs/graphene as the cathode. This device showed both large energy densities (124 W h kg\u22121, 11.2 mW h cm\u22123) and impressive power densities (60 kW kg\u22121, 5.4 W h cm\u22123), indicating that both the introducing of Nb2O5 and the unique continuous mesoporous network architecture played a crucial role in the enhancement of the electrochemical properties.", "question": "What's the anode?", "answer": "CNFs/Nb2O5", "answer_start": 974}
{"document_id": 75548, "context": "A good dopant must endow the cathode material with superior cyclability. According to Fig. 1(a), among Cu, Ti, Mg and Zn, Mg and Zn are better dopants. From structural view, a good dopant should be able to segregate into precipitates during cycling, offering better material integration. However, when cycled at a lower upper cutoff voltage of 4.3 V, Mg dopant segregation cannot be activated. Therefore, Mg-doped P2-NMM10 shows comparable cyclability to Cu-doped P2-NMC10, which is shown in Fig. S10.\u2020 Intriguingly, when cycled at 4.3 V, the Zn-doped sample shows even better cycling stability (91% retention after 100 cycles). Fig. 5(a) shows the capacity retentions of the P2-NMZ10 electrodes at different upper cutoff voltages, from which we can see that Zn-doped P2-NMZ10 shows superior capacity retentions in all voltage windows. The corresponding TEM analysis on the cycled P2-NMZ10 samples shows that the Zn-dopant can form precipitates under all cycling conditions as shown in Fig. 5(b\u2013i), which explains why P2-NMZ10 shows much higher cycling stability. Although increasing the upper cutoff voltage can accelerate the precipitate formation process, material degradation is also aggravated during high voltage cycling. Therefore, a good dopant should enable dopant precipitate formation easily, especially at low cycling voltage.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75549, "context": "Supercapacitors have high power density and a long lifespan but poor energy density in contrast with rechargeable batteries, restricting their widespread applications. Adding soluble redox-active ingredients into electrolyte is an effective strategy to increase specific energy. However, an ion-selective membrane is generally needed in such supercapacitors to avoid the mixing of anolyte and catholyte, which significantly increases the cost. Here we report a supercapacitor that consists of a modified solid Ti3C2Tx anode and an active catholyte containing Mn2+, where the conversion between soluble Mn2+ and solid MnO2 occurs at the cathode, and the redox of Ti\u2013O with the bonding/de-bonding of H3O+ occurs at the anode. Impressively, this hybrid supercapacitor displays a gratifying specific energy of 43.4 W h kg\u22121, without using any ion-selective membrane, and excellent cycling stability over 20000 cycles. Moreover, we also demonstrate its superior low-temperature performance even though the electrolyte has been frozen at \u221270 \u00b0C.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75534, "context": "Although STEM-HAADF imaging has become the most widely used imaging mode in STEM, the strong atomic number dependency of STEM-HAADF contrast also means that the imaging contrast of light atoms is easily submerged by the adjacent heavy atoms. In contrast, STEM-ABF phase-contrast imaging based on wave interference provides better visualization of light elements with the presence of heavy elements, such as oxygen in the SrTiO3 crystal, lithium in LiCoO2 and even hydrogen in metal hydrides. An elegant example was reported by Gu et al., in which aberration-corrected STEM-ABF imaging was applied to directly visualize lithium columns in LiFePO4 and identify an intriguing lithium staging structure in the partially delithiated LixFePO4 (x \u2248 0.5) crystal. Fig. 6(a\u2013c) present the atomic-resolution STEM-ABF images of the LiFePO4 cathode at different charging states. Compared with the pristine and fully-charged structures of LiFePO4 in Fig. 6(a and b), half-delithiated LiFePO4 in Fig. 6(c) demonstrated that part of the lithium remains in the lattice (yellow circles) at every other row of Li-extracted sites (orange circles). This ordered structure contradicted the previous model of LiFePO4/FePO4 two-phase separation, but was analogous to the stage-II phase in some layer compounds, and contributed to minimizing the Li\u2013Li repulsive interaction to stabilize this intermediate phase. This result indicated that a continuous phase transition occurred in partially delithiated LixFePO4 through a metastable phase and helped to understand the high-rate capability of LiFePO4 cathode.", "question": "What's the cathode?", "answer": " LiFePO4", "answer_start": 820}
{"document_id": 75534, "context": "Although STEM-HAADF imaging has become the most widely used imaging mode in STEM, the strong atomic number dependency of STEM-HAADF contrast also means that the imaging contrast of light atoms is easily submerged by the adjacent heavy atoms. In contrast, STEM-ABF phase-contrast imaging based on wave interference provides better visualization of light elements with the presence of heavy elements, such as oxygen in the SrTiO3 crystal, lithium in LiCoO2 and even hydrogen in metal hydrides. An elegant example was reported by Gu et al., in which aberration-corrected STEM-ABF imaging was applied to directly visualize lithium columns in LiFePO4 and identify an intriguing lithium staging structure in the partially delithiated LixFePO4 (x \u2248 0.5) crystal. Fig. 6(a\u2013c) present the atomic-resolution STEM-ABF images of the LiFePO4 cathode at different charging states. Compared with the pristine and fully-charged structures of LiFePO4 in Fig. 6(a and b), half-delithiated LiFePO4 in Fig. 6(c) demonstrated that part of the lithium remains in the lattice (yellow circles) at every other row of Li-extracted sites (orange circles). This ordered structure contradicted the previous model of LiFePO4/FePO4 two-phase separation, but was analogous to the stage-II phase in some layer compounds, and contributed to minimizing the Li\u2013Li repulsive interaction to stabilize this intermediate phase. This result indicated that a continuous phase transition occurred in partially delithiated LixFePO4 through a metastable phase and helped to understand the high-rate capability of LiFePO4 cathode.", "question": "What's the cathode?", "answer": "LiFePO4", "answer_start": 1568}
{"document_id": 75540, "context": "By comparing the C 1s, Li 1s, and O 1s XPS spectra and the corresponding area proportions, we found corroborative results. Firstly, a great amount of residual carbonate on the pristine LiNiO2 surface illustrates the continued challenge in avoiding carbonate formation during calcination and quick transferal. There was a clear increase in inorganic carbonates (C 1s, Li 1s, and O 1s XPS spectra) concurrent with the decrease of lattice Li and O proportions after exposure to ambient environment, which was amplified under continuous human exhalation (lattice Li and O are almost negligible on the surface) (Fig. 1). This is indicative of the continuous formation of inorganic carbonates, which strongly attenuates the photoelectron signals from underneath LiNiO2 layers. Our observation is consistent with previous studies suggesting that dense concentration of water and CO2 on the oxide cathode surface facilitates chemical reactions to yield increased amounts of surface inorganic carbonates. Previous studies have shown the surface chemical bonding and structure of NMC materials are readily transformed by certain environments, including CO2, H2O, O2, and other reactive gases in a glove box. These gases react with layered oxides by extracting lithium from the lattice, further generating LiOH and/or Li2CO3 as well as oxygen vacancies. Lithium residuals on NMC and NCA materials also have been confirmed by infrared spectroscopy, Raman spectroscopy, and TEM. It is a consensus that surface instability is one of the common challenges for many battery materials. Other materials, such as sodium-containing layered cathode materials and Li-rich materials, also encounter surface-air instability, which leads to Na/Li residual formation and elevated pH on the particle surfaces. For sodium-containing layered cathode materials, water intercalation or Na+/H+ exchange also takes place, which can disrupt the layered structure. These changes would trigger slurry alkalization, degassing problem, and electrolyte decomposition. Based on our results and previous findings, we recommend that the details about sample handling should be specified in the journal publications, especially those involving delicate surface chemical analysis.", "question": "What's the cathode?", "answer": "sodium-containing layered", "answer_start": 1787}
{"document_id": 75540, "context": "By comparing the C 1s, Li 1s, and O 1s XPS spectra and the corresponding area proportions, we found corroborative results. Firstly, a great amount of residual carbonate on the pristine LiNiO2 surface illustrates the continued challenge in avoiding carbonate formation during calcination and quick transferal. There was a clear increase in inorganic carbonates (C 1s, Li 1s, and O 1s XPS spectra) concurrent with the decrease of lattice Li and O proportions after exposure to ambient environment, which was amplified under continuous human exhalation (lattice Li and O are almost negligible on the surface) (Fig. 1). This is indicative of the continuous formation of inorganic carbonates, which strongly attenuates the photoelectron signals from underneath LiNiO2 layers. Our observation is consistent with previous studies suggesting that dense concentration of water and CO2 on the oxide cathode surface facilitates chemical reactions to yield increased amounts of surface inorganic carbonates. Previous studies have shown the surface chemical bonding and structure of NMC materials are readily transformed by certain environments, including CO2, H2O, O2, and other reactive gases in a glove box. These gases react with layered oxides by extracting lithium from the lattice, further generating LiOH and/or Li2CO3 as well as oxygen vacancies. Lithium residuals on NMC and NCA materials also have been confirmed by infrared spectroscopy, Raman spectroscopy, and TEM. It is a consensus that surface instability is one of the common challenges for many battery materials. Other materials, such as sodium-containing layered cathode materials and Li-rich materials, also encounter surface-air instability, which leads to Na/Li residual formation and elevated pH on the particle surfaces. For sodium-containing layered cathode materials, water intercalation or Na+/H+ exchange also takes place, which can disrupt the layered structure. These changes would trigger slurry alkalization, degassing problem, and electrolyte decomposition. Based on our results and previous findings, we recommend that the details about sample handling should be specified in the journal publications, especially those involving delicate surface chemical analysis.", "question": "What's the cathode?", "answer": "oxide ", "answer_start": 883}
{"document_id": 75545, "context": "Similarly to TiS2, NbS2 also shows a high electrochemical activity upon Li+ intercalation/deintercalation at potentials between 1.5 and 3.0 V, presenting a specific capacity of about 100 mA h g\u22121. Xiao et al. systematically investigated the reaction kinetics and electrochemical performance of a ternary hybrid sulfur cathode consisting of sandwich-type NbS2@S enveloped by iodine-doped graphene (IG). As an exhilarating discovery, the active sulfur species can be intercalated in the interlayers of NbS2, which further enhances the intrinsic conductivity and polarity of NbS2. Therefore, the introduction of NbS2 and IG into a Li\u2013S cell cathode shows a synergistic effect for LiPS fixation and utilization. Adsorption experiments indicate that NbS2 and NbS2\u2013IG visibly decolorize the Li2S6 solution, while G and IG only change the solution color from tawny to yellow, suggesting that NbS2 possesses much stronger affinity to LiPSs than G and IG. CV tests using symmetrical cells that are fabricated by sandwiching a Li2S6-containing electrolyte between two identical electrodes reveal that the G and IG electrodes only show a small current density, while the current density in NbS2 is significantly increased, and further improvement is observed in the NbS2\u2013IG electrode. These results suggest that NbS2 is conducive to providing access for electric charge to the NbS2\u2013LiPS interface and synchronously triggers the redox reactions of LiPSs. Consequently, reversible capacities of 195, 107, and 74 mA h g\u22121 (1.05 mg cm\u22122) are achieved after 2000 cycles at ultrahigh rates of 20, 30, and 40C, respectively, and a high discharge capacity of 405 mA h g\u22121 (3.25 mg cm\u22122) is maintained after 600 cycles at 1C. This work sheds light on the promising application of 2D layered metal sulfides in high-energy, high-power, and long-life Li\u2013S batteries.", "question": "What's the cathode?", "answer": "sulfur ", "answer_start": 311}
{"document_id": 75547, "context": "The crystal structure of the current collectors was characterized using a Rigaku D/max-2200/PC X-ray diffractometer (XRD) with Cu K\u03b1 radiation (\u03bb = 0.154 nm). The surface morphology of the samples was observed via field-emission scanning electron microscopy (FE-SEM, JEOL, JSM-6700F). Specifically, to characterize the morphology of the lithium metal anodes (LMAs), the coin cells were initially disassembled, the LMAs were extracted and rinsed with DOL/DME cosolvent to remove the residual electrolyte, and finally dried in a glove box. The LMAs were sealed in an air-tight plastic sample box before transferring them from the glove box to the SEM chamber. The coin cells were assembled with the abovementioned protocol in an argon-filled glove box. Coulombic efficiencies (CEs) were tested under different current densities and capacities at room temperature using a LAND battery test instrument. A certain amount of Li metal was initially electrodeposited on an NPAuLi3@NF or NF current collector, and then the cell was charged to 0.1 V (vs. Li+/Li) to strip the Li metal. The cut-off voltage of 0.1 V was set to prevent dealloying of the AuLi alloy. For long-term cycling and full cell tests, 3 mA h cm\u22122 of Li metal was firstly deposited on the current collectors, and then the cells were subjected to charge/discharge cycling at different current densities and capacities. LiFePO4 with an areal mass loading of 1.72 mg cm\u22122 was used as the cathode material in the full cell tests. The electrochemical impedance spectroscopy (EIS) study was conducted using a ZIVE SP1 electrochemical workstation in the frequency range of 100 kHz to 10 MHz with an AC potential amplitude of 5 mV.", "question": "What's the cathode?", "answer": "LiFePO4 ", "answer_start": 1379}
{"document_id": 75553, "context": "To directly observe and verify the possible contact loss between the cathode and solid electrolyte, FIB-SEM tomography was used to characterize the microstructural evolution in the composite cathode during cycling. Three SSB cells (before cycling, after 10 cycles, and after 50 cycles) were extracted in the discharged state and evaluated using FIB-SEM tomography. The workflow for the FIB-SEM tomography experiment is presented in Fig. 2. The SSB full cell was tilted at a 52\u00b0 angle with the cathode composite perpendicular to the ion beam. The ion beam was first used to mill trenches surrounding the area of interest, exposing the cross-section to the top-mounted electron beam at a 52\u00b0 angle. A backscattered electron (BSE) image was acquired to provide 2D morphology information on the cathode composite. Then, a thin slice (50 nm) was milled away from the cross-section with the ion beam, and another BSE image was taken. After repeating this process several hundred times, the image stack was aligned, cropped, and combined into a 2D image stack (Fig. 2(c)) (see ESI Fig. S2 and S3\u2020 for the detailed image process procedures). The 2D image stack and corresponding four-phase segmentation image are presented in Fig. 2(c) and (d), respectively, whereby the NMC cathode (blue), LPS solid electrolyte (yellow), carbon (black), and void (red) can be accurately distinguished. The segmented image stacks were then reconstructed into a 3D volume. The reconstructed structures of the composite cathodes before and after electrochemical cycling are presented in Fig. 3.", "question": "What's the cathode?", "answer": "NMC ", "answer_start": 1263}
{"document_id": 75555, "context": "The development of primary batteries with high energy density, long shelf life, and stable discharge voltage is essential for civilization and military applications. Primary batteries with high power output and excellent low-temperature performance can further broaden their application. Herein, a Li/LiV2(PO4)3 primary battery was proposed and investigated for the first time. In order to improve the shelf life of the Li/LiV2(PO4)3 primary battery, the mechanism and corresponding inhibition strategy of self-discharge were studied in detail. It was found that the electrolyte composition is a key factor affecting the shelf life of Li/LiV2(PO4)3 primary batteries, where the corrosion of aluminum (Al) current collector triggered by the organic radical cations generated from electrochemical oxidation of the ethylene carbonate (EC) at high potential; and the detrimental reaction between LiV2(PO4)3 and electrolyte lead to the self-discharge of the Li/LiV2(PO4)3 primary battery. When the EC solvent was replaced by the propylene carbonate (PC) solvent, the corrosion of Al foil was alleviated. Moreover, the addition of lithium bis(oxalato)borate (LiBOB) to the electrolyte could improve the stability of cathode/electrolyte interface and enhance the shelf life of the Li/LiV2(PO4)3 primary battery. As a result, 100% capacity could be maintained after over one-month storage, 86% energy could be maintained at 50C, and 63% energy could be maintained at \u221240 \u00b0C at a current density of 0.1C. In addition, the Li/LiV2(PO4)3 primary battery showed great potential for all-weather applications.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75559, "context": "The charging process of the Li\u2013CO2 battery was also studied systematically (Fig. 5). The Li\u2013CO2 battery with no illumination exhibits a high charge voltage of about 4.17 V, whereas the charge voltage sharply drops to 3.28 V after illumination (Fig. 5a). Impressively, the photo-assisted Li\u2013CO2 battery with the SiC/RGO cathode outperforms the majority of Li\u2013CO2 batteries (Table S1\u2020). Furthermore, the fast response of the charge voltage to the on\u2013off irradiation (Fig. S10\u2020) demonstrates the superior kinetics under illumination, which is partially responsible for the decrease of charge overpotential. As presented in Fig. 5b, LSV curves of the batteries obtained under illumination also show a lower onset voltage and higher current density compared with that in the absence of light, in accordance with the galvanostatic charging profiles. Such a light response phenomenon presented in the charging process further supports the proposed working mechanism for the photo-assisted Li\u2013CO2 batteries (Fig. 1c): the photoexcited holes play a key role in the decomposition of the discharge products due to their high oxidation capability. Thus, reduction of the charge voltage could be achieved by providing extra energy from light irradiation to compensate the required input energy from the external circuit. Also, the kinetics of the battery could be promoted under illumination in virtue of the quick response of the photo-excitation process compared to that of the electric field, which is also beneficial in reducing the charging overpotential. The morphology evolution of the discharge products upon charging was further investigated via SEM analysis. After the recharge process under illumination, the nanosheet-like discharge product disappears completely (Fig. 5d), whereas some membranous discharge product remains on the surface of the cathode charged in the absence of light (Fig. 5e). Analogously, XRD patterns of recharged cathodes show that the typical diffraction peaks of Li2CO3 completely disappear after photo-assisted charging, while these peaks still exist after being recharged without illumination (Fig. 5c and S7\u2020), consistent with the results obtained from FTIR spectra (Fig. 5f and S8\u2020). Overall, the light-assisted Li\u2013CO2 battery possesses better reversibility in comparison with the conventional Li\u2013CO2 battery, owing to the facile CO2ER process promoted by the photogenerated holes.", "question": "What's the cathode?", "answer": "SiC/RGO", "answer_start": 311}
{"document_id": 75562, "context": "Then Li\u2013O2 batteries were fabricated with PFOSF treated Li anodes. A carbon nanotube film was used as the air-cathode and 1 M LiTFSI in TEGDME as the electrolyte. The fabricated LOBs were charged and discharged repeatedly. SEM and XRD results (Fig. S12\u2020) show that the cathode side reaction is reversible. As shown in Fig. 5, the bare Li based cell can only cycle for 43 cycles with the discharge voltage suddenly dropped to 2.1 V at a current density of 300 mA g\u22121 with the capacity limited at 1000 mA h g\u22121. To find out the reason, the cell was disassembled after cycling for 10 cycles, the bare Li foil became black and many cracks and pulverizations were observed under SEM (Fig. S13a and c\u2020). In contrast, LOBs with the PFOSF based Li anode exhibited largely improved cycling performance which could be enhanced to 185 cycles without using any cathode catalyst (Fig. 5). The Li surface was flat and kept its pristine silvery color after 10 cycles with about 40 \u03bcm thickness of the protective film covered on the Li surface (Fig. S13b and d\u2020). LOBs with different SEI thicknesses were assembled and tested. As shown in Fig. S14,\u2020 the cycling performance was improved. The cycle life was elongated to 104, 92, 140, 185 and 167 cycles after PFOSF treatment for 10, 20, 30, 60 and 180 min, respectively, so the optimized PFOSF treatment time is 60 min. The EIS of the LOBs further explained this phenomenon. In Fig. S15,\u2020 the ohmic resistance (Rs) and charge transfer resistance (Rc) gradually increased within 30 cycles for LOBs with the pristine Li anode, which was induced by the pulverization of the Li anode and accumulation of side products due to the severe side reactions of Li metal with the O2-rich electrolyte. In contrast, for PFOSF-Li based LOBs, the values of Rohm and Rctr almost remained stable, which were far smaller than those of bare LOBs, indicating the well protecting effect of the LiF coating on the Li surface in suppressing the side reactions of Li metal with the electrolyte.", "question": "What's the cathode?", "answer": "air-cathode", "answer_start": 106}
{"document_id": 75562, "context": "Then Li\u2013O2 batteries were fabricated with PFOSF treated Li anodes. A carbon nanotube film was used as the air-cathode and 1 M LiTFSI in TEGDME as the electrolyte. The fabricated LOBs were charged and discharged repeatedly. SEM and XRD results (Fig. S12\u2020) show that the cathode side reaction is reversible. As shown in Fig. 5, the bare Li based cell can only cycle for 43 cycles with the discharge voltage suddenly dropped to 2.1 V at a current density of 300 mA g\u22121 with the capacity limited at 1000 mA h g\u22121. To find out the reason, the cell was disassembled after cycling for 10 cycles, the bare Li foil became black and many cracks and pulverizations were observed under SEM (Fig. S13a and c\u2020). In contrast, LOBs with the PFOSF based Li anode exhibited largely improved cycling performance which could be enhanced to 185 cycles without using any cathode catalyst (Fig. 5). The Li surface was flat and kept its pristine silvery color after 10 cycles with about 40 \u03bcm thickness of the protective film covered on the Li surface (Fig. S13b and d\u2020). LOBs with different SEI thicknesses were assembled and tested. As shown in Fig. S14,\u2020 the cycling performance was improved. The cycle life was elongated to 104, 92, 140, 185 and 167 cycles after PFOSF treatment for 10, 20, 30, 60 and 180 min, respectively, so the optimized PFOSF treatment time is 60 min. The EIS of the LOBs further explained this phenomenon. In Fig. S15,\u2020 the ohmic resistance (Rs) and charge transfer resistance (Rc) gradually increased within 30 cycles for LOBs with the pristine Li anode, which was induced by the pulverization of the Li anode and accumulation of side products due to the severe side reactions of Li metal with the O2-rich electrolyte. In contrast, for PFOSF-Li based LOBs, the values of Rohm and Rctr almost remained stable, which were far smaller than those of bare LOBs, indicating the well protecting effect of the LiF coating on the Li surface in suppressing the side reactions of Li metal with the electrolyte.", "question": "What's the anode?", "answer": " Li", "answer_start": 736}
{"document_id": 75562, "context": "Then Li\u2013O2 batteries were fabricated with PFOSF treated Li anodes. A carbon nanotube film was used as the air-cathode and 1 M LiTFSI in TEGDME as the electrolyte. The fabricated LOBs were charged and discharged repeatedly. SEM and XRD results (Fig. S12\u2020) show that the cathode side reaction is reversible. As shown in Fig. 5, the bare Li based cell can only cycle for 43 cycles with the discharge voltage suddenly dropped to 2.1 V at a current density of 300 mA g\u22121 with the capacity limited at 1000 mA h g\u22121. To find out the reason, the cell was disassembled after cycling for 10 cycles, the bare Li foil became black and many cracks and pulverizations were observed under SEM (Fig. S13a and c\u2020). In contrast, LOBs with the PFOSF based Li anode exhibited largely improved cycling performance which could be enhanced to 185 cycles without using any cathode catalyst (Fig. 5). The Li surface was flat and kept its pristine silvery color after 10 cycles with about 40 \u03bcm thickness of the protective film covered on the Li surface (Fig. S13b and d\u2020). LOBs with different SEI thicknesses were assembled and tested. As shown in Fig. S14,\u2020 the cycling performance was improved. The cycle life was elongated to 104, 92, 140, 185 and 167 cycles after PFOSF treatment for 10, 20, 30, 60 and 180 min, respectively, so the optimized PFOSF treatment time is 60 min. The EIS of the LOBs further explained this phenomenon. In Fig. S15,\u2020 the ohmic resistance (Rs) and charge transfer resistance (Rc) gradually increased within 30 cycles for LOBs with the pristine Li anode, which was induced by the pulverization of the Li anode and accumulation of side products due to the severe side reactions of Li metal with the O2-rich electrolyte. In contrast, for PFOSF-Li based LOBs, the values of Rohm and Rctr almost remained stable, which were far smaller than those of bare LOBs, indicating the well protecting effect of the LiF coating on the Li surface in suppressing the side reactions of Li metal with the electrolyte.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75573, "context": "Vanadium sulfides, such as VS2, have been often used as sulfur host materials for lithium\u2013sulfur batteries (LSBs), however, their high-symmetry and layered crystalline structure often lead to a poor rate-capability and a limited cycling stability of the resultant LSBs. Thus, in this work, a type of distorted NiAs-type structured V2S3 phase was designed and attempted to use it as a sulfur host for LSBs. The results showed that the prepared V2S3-nanocrystal decorated carbon nanofiber (CNF@V2S3) electrode films are freestanding, highly conductive and flexible. And the resultant CNF@V2S3/S cathodes show a high specific capacity (1169 mA h g\u22121 at 0.1C), an excellent rate capability (retain 78.9% at 2.0C), an ultra-low delay rate per cycle of 0.0071%, and a low self-discharge rate of 3.65% per month. A series of analyses indicate that these high electrochemical performances are mainly due to the high polarity, high conductivity and high catalytic activity of V2S3 nanocrystals, as well as the improved diffusivities of Li ions. This research could provide some new insight into the design of sulfur host materials for high-performance LSBs.", "question": "What's the cathode?", "answer": "CNF@V2S3/S ", "answer_start": 582}
{"document_id": 75574, "context": "Along with the high PCE of the cSiPV module described above, much attention should be paid to photoelectric-charge/galvanostatic-discharge capability (i.e., electrochemical redox kinetics) of the bQSSB to develop highly efficient cSiPV\u2013bQSSB. To this end, we chose LiCoO2 (LCO) and Li4Ti5O12 (LTO) as cathode and anode active materials in the bQSSB, respectively, owing to their fast rate performance and structural stability. Other electrode active materials with high capacities and wide electrochemical voltages can be used to develop advanced bQSSBs, which will be an interesting topic in future studies. In addition, to secure well-interconnected electronic networks in the battery electrodes that are affected by dispersibility of conductive additives (herein, carbon black (CB) powders), we modified the surface of CB powders in the electrodes. The CB powders were grafted with diethylenetriamine (DETA) to promote their inter-particle repulsion. The DETA grafting process is described in the Experimental section. The beneficial effects of the DETA-modified CB (denoted as DETA CB) powders on the formation of the electronic networks are conceptually illustrated in Fig. 2A. The X-ray photoelectron spectroscopy (XPS) spectra (Fig. 2B) showed characteristic N 1s peaks around 400 eV (assigned to amine groups), verifying the successful grafting of DETA on the CB powders. Additionally, the zeta potential of the DETA CB powders was +32 mV (vs. + 0.5 mV of the pristine CB powders), revealing the enhanced electrostatic repulsion between the powders (Fig. 2C).", "question": "What's the cathode?", "answer": " LiCoO2 (LCO)", "answer_start": 264}
{"document_id": 75574, "context": "Along with the high PCE of the cSiPV module described above, much attention should be paid to photoelectric-charge/galvanostatic-discharge capability (i.e., electrochemical redox kinetics) of the bQSSB to develop highly efficient cSiPV\u2013bQSSB. To this end, we chose LiCoO2 (LCO) and Li4Ti5O12 (LTO) as cathode and anode active materials in the bQSSB, respectively, owing to their fast rate performance and structural stability. Other electrode active materials with high capacities and wide electrochemical voltages can be used to develop advanced bQSSBs, which will be an interesting topic in future studies. In addition, to secure well-interconnected electronic networks in the battery electrodes that are affected by dispersibility of conductive additives (herein, carbon black (CB) powders), we modified the surface of CB powders in the electrodes. The CB powders were grafted with diethylenetriamine (DETA) to promote their inter-particle repulsion. The DETA grafting process is described in the Experimental section. The beneficial effects of the DETA-modified CB (denoted as DETA CB) powders on the formation of the electronic networks are conceptually illustrated in Fig. 2A. The X-ray photoelectron spectroscopy (XPS) spectra (Fig. 2B) showed characteristic N 1s peaks around 400 eV (assigned to amine groups), verifying the successful grafting of DETA on the CB powders. Additionally, the zeta potential of the DETA CB powders was +32 mV (vs. + 0.5 mV of the pristine CB powders), revealing the enhanced electrostatic repulsion between the powders (Fig. 2C).", "question": "What's the anode?", "answer": " Li4Ti5O12 (LTO)", "answer_start": 281}
{"document_id": 75412, "context": "Low-cost and high-safety aqueous Zn ion batteries have been considered as promising alternatives to Li-ion batteries, provided that a stable Zn metal anode could be developed. The dendrite growth and the low Coulombic efficiency (CE) are the primary two issues afflicting the design of advanced Zn metal anode. Inspired by the complexing agent in the electroplating industry, acetonitrile (AN) is proposed as an electrolyte additive to guide the smooth growth of Zn. The enhanced intermolecular interactions between Zn2+ and the mixed H2O/AN solvents lead to the supersaturating of adatoms on the current collector, as revealed by the complementary theoretical and experimental studies. Consequently, homogeneous nucleation and smooth growth of Zn is enabled for achieving exceptional stability up to 1000 cycles with an excellent CE of 99.64% on average. Application-wise, the incorporation of complexing agent in the electrolyte is fully compatible with the cathode while maintains the non-flammable nature for safe operation. The solvation chemistry regulation strategy provides a promising route to stabilize Zn metal anodes.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75412, "context": "Low-cost and high-safety aqueous Zn ion batteries have been considered as promising alternatives to Li-ion batteries, provided that a stable Zn metal anode could be developed. The dendrite growth and the low Coulombic efficiency (CE) are the primary two issues afflicting the design of advanced Zn metal anode. Inspired by the complexing agent in the electroplating industry, acetonitrile (AN) is proposed as an electrolyte additive to guide the smooth growth of Zn. The enhanced intermolecular interactions between Zn2+ and the mixed H2O/AN solvents lead to the supersaturating of adatoms on the current collector, as revealed by the complementary theoretical and experimental studies. Consequently, homogeneous nucleation and smooth growth of Zn is enabled for achieving exceptional stability up to 1000 cycles with an excellent CE of 99.64% on average. Application-wise, the incorporation of complexing agent in the electrolyte is fully compatible with the cathode while maintains the non-flammable nature for safe operation. The solvation chemistry regulation strategy provides a promising route to stabilize Zn metal anodes.", "question": "What's the anode?", "answer": "Zn metal", "answer_start": 141}
{"document_id": 75412, "context": "Low-cost and high-safety aqueous Zn ion batteries have been considered as promising alternatives to Li-ion batteries, provided that a stable Zn metal anode could be developed. The dendrite growth and the low Coulombic efficiency (CE) are the primary two issues afflicting the design of advanced Zn metal anode. Inspired by the complexing agent in the electroplating industry, acetonitrile (AN) is proposed as an electrolyte additive to guide the smooth growth of Zn. The enhanced intermolecular interactions between Zn2+ and the mixed H2O/AN solvents lead to the supersaturating of adatoms on the current collector, as revealed by the complementary theoretical and experimental studies. Consequently, homogeneous nucleation and smooth growth of Zn is enabled for achieving exceptional stability up to 1000 cycles with an excellent CE of 99.64% on average. Application-wise, the incorporation of complexing agent in the electrolyte is fully compatible with the cathode while maintains the non-flammable nature for safe operation. The solvation chemistry regulation strategy provides a promising route to stabilize Zn metal anodes.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75412, "context": "Low-cost and high-safety aqueous Zn ion batteries have been considered as promising alternatives to Li-ion batteries, provided that a stable Zn metal anode could be developed. The dendrite growth and the low Coulombic efficiency (CE) are the primary two issues afflicting the design of advanced Zn metal anode. Inspired by the complexing agent in the electroplating industry, acetonitrile (AN) is proposed as an electrolyte additive to guide the smooth growth of Zn. The enhanced intermolecular interactions between Zn2+ and the mixed H2O/AN solvents lead to the supersaturating of adatoms on the current collector, as revealed by the complementary theoretical and experimental studies. Consequently, homogeneous nucleation and smooth growth of Zn is enabled for achieving exceptional stability up to 1000 cycles with an excellent CE of 99.64% on average. Application-wise, the incorporation of complexing agent in the electrolyte is fully compatible with the cathode while maintains the non-flammable nature for safe operation. The solvation chemistry regulation strategy provides a promising route to stabilize Zn metal anodes.", "question": "What's the anode?", "answer": "Zn metal", "answer_start": 295}
{"document_id": 75413, "context": "Novel portable power sources featuring high flexibility, built-in sustainability and enhanced safety have attracted ever-increasing attention in the field of wearable electronics. Herein, a novel flexible self-charging sodium-ion full battery was feasibly fabricated by sandwiching a BaTiO3-P(VDF-HFP)-NaClO4 piezoelectric gel-electrolyte film between an advanced Na3V2(PO4)3@C cathode and hard carbon anode. Besides the considerable flexibility and electrochemical storage performance, the as-designed device also delivers sound self-charging capability via various stress patterns, regardless of whether under static compression, repeated bending or continuous palm patting. Serially connected self-charging devices are able to drive several electronic devices with a good working state. Specifically, a unique theory of electromagnetic fields was successfully introduced to deduce the direct self-charging mechanism, where no rectifier was applied and the battery was charged by the built-in piezoelectric component. This work presents an innovative approach to achieve a new sustainable, safe and flexible sodium-ion battery for self-powered wearable electronics.", "question": "What's the cathode?", "answer": "Na3V2(PO4)3@C", "answer_start": 364}
{"document_id": 75413, "context": "Novel portable power sources featuring high flexibility, built-in sustainability and enhanced safety have attracted ever-increasing attention in the field of wearable electronics. Herein, a novel flexible self-charging sodium-ion full battery was feasibly fabricated by sandwiching a BaTiO3-P(VDF-HFP)-NaClO4 piezoelectric gel-electrolyte film between an advanced Na3V2(PO4)3@C cathode and hard carbon anode. Besides the considerable flexibility and electrochemical storage performance, the as-designed device also delivers sound self-charging capability via various stress patterns, regardless of whether under static compression, repeated bending or continuous palm patting. Serially connected self-charging devices are able to drive several electronic devices with a good working state. Specifically, a unique theory of electromagnetic fields was successfully introduced to deduce the direct self-charging mechanism, where no rectifier was applied and the battery was charged by the built-in piezoelectric component. This work presents an innovative approach to achieve a new sustainable, safe and flexible sodium-ion battery for self-powered wearable electronics.", "question": "What's the anode?", "answer": "hard carbon", "answer_start": 390}
{"document_id": 75413, "context": "Novel portable power sources featuring high flexibility, built-in sustainability and enhanced safety have attracted ever-increasing attention in the field of wearable electronics. Herein, a novel flexible self-charging sodium-ion full battery was feasibly fabricated by sandwiching a BaTiO3-P(VDF-HFP)-NaClO4 piezoelectric gel-electrolyte film between an advanced Na3V2(PO4)3@C cathode and hard carbon anode. Besides the considerable flexibility and electrochemical storage performance, the as-designed device also delivers sound self-charging capability via various stress patterns, regardless of whether under static compression, repeated bending or continuous palm patting. Serially connected self-charging devices are able to drive several electronic devices with a good working state. Specifically, a unique theory of electromagnetic fields was successfully introduced to deduce the direct self-charging mechanism, where no rectifier was applied and the battery was charged by the built-in piezoelectric component. This work presents an innovative approach to achieve a new sustainable, safe and flexible sodium-ion battery for self-powered wearable electronics.", "question": "What's the electrolyte?", "answer": "BaTiO3-P(VDF-HFP)-NaClO4", "answer_start": 284}
{"document_id": 75415, "context": "We have successfully synthesized a self-supported CoFe@NCNT/CFC electrode for mechanically flexible ZABs, through a facile strategy. The optimized CoFe@NCNT/CFC cathode shows excellent bifunctional electrocatalytic activities with a half-wave potential of 0.873 V for the ORR and E10 = 1.506 V for the OER. The flexible all-solid-state ZABs with the CoFe@NCNT/CFC cathode exhibit a large open-circuit voltage of 1.426 V and a large power density of 37.7 mW cm\u22122 as well as robust stability. More importantly, ZABs assembled with the self-supported CoFe@NCNT/CFC cathode can still work even under extreme bending conditions. Our strategy opens a new way for flexible self-supported catalysts for high-performance portable and rechargeable energy storage devices.", "question": "What's the cathode?", "answer": "CoFe@NCNT/CFC", "answer_start": 147}
{"document_id": 75415, "context": "We have successfully synthesized a self-supported CoFe@NCNT/CFC electrode for mechanically flexible ZABs, through a facile strategy. The optimized CoFe@NCNT/CFC cathode shows excellent bifunctional electrocatalytic activities with a half-wave potential of 0.873 V for the ORR and E10 = 1.506 V for the OER. The flexible all-solid-state ZABs with the CoFe@NCNT/CFC cathode exhibit a large open-circuit voltage of 1.426 V and a large power density of 37.7 mW cm\u22122 as well as robust stability. More importantly, ZABs assembled with the self-supported CoFe@NCNT/CFC cathode can still work even under extreme bending conditions. Our strategy opens a new way for flexible self-supported catalysts for high-performance portable and rechargeable energy storage devices.", "question": "What's the cathode?", "answer": "CoFe@NCNT/CFC", "answer_start": 350}
{"document_id": 75414, "context": "Likewise, the cycling performances of bare and coated LMO cathodes were compared using a half-cell (Li|LMO). The cycling performance of the Li|LMO half-cell was examined within the voltage range of 3.3to 4.5 V at 55 \u00b0C. The charge and discharge voltage profiles of the bare LMO and surface modified LMO samples (PLMO-10 min, LMO-10 min, and LMO-30 min) are presented in Fig. S3a.\u2020 The initial discharge capacity of bare LMO, PLMO-10 min, LMO-10 min, and LMO-30 min are 128.01, 125.42, 127.52, and 130.144 mA h gLMO\u22121 at 0.3C and 55 \u00b0C, respectively. Fig. S3b\u2020 displays the cycling performances of all samples measured with the bare LMO and PVDF@LGLZNO fibrous film coated LMO half-cells at 0.3C and 55 \u00b0C. The discharge capacity of bare LMO sharply fades to 11 mA h gLMO\u22121 (9% capacity retention) after 100 cycles, while those of PLMO-10 min, LMO-10 min, and LMO-30 min were 15, 38, and 110 mA h gLMO\u22121 after 100 cycles at 55 \u00b0C and 0.3C, corresponding to capacity retentions of 12.20%, 30.14%, and 83.29%, respectively. Also, the cycling performance of the cell with LMO-50 min at 55 \u00b0C and 0.3C is depicted in Fig. S3c.\u2020 The above results indicate that LMO-30 min demonstrates better cycling performance at 55 \u00b0C compared to other cells, while the bare and PLMO coated cathodes have poor resistance to elevated temperature. The corresponding cells degrade faster than they did at 25 \u00b0C as seen in Fig. 2b. The effect of coating on capacity retention at 25 \u00b0C and 55 \u00b0C is apparent. The optimized PVDF@LGLZNO fibrous film coated on the surface of the LMO electrode acts as a better protective film that could substantially decrease manganese dissolution at high temperatures and minimize the adverse effects caused by electrolyte decomposition.", "question": "What's the cathode?", "answer": "coated LMO", "answer_start": 47}
{"document_id": 75414, "context": "Likewise, the cycling performances of bare and coated LMO cathodes were compared using a half-cell (Li|LMO). The cycling performance of the Li|LMO half-cell was examined within the voltage range of 3.3to 4.5 V at 55 \u00b0C. The charge and discharge voltage profiles of the bare LMO and surface modified LMO samples (PLMO-10 min, LMO-10 min, and LMO-30 min) are presented in Fig. S3a.\u2020 The initial discharge capacity of bare LMO, PLMO-10 min, LMO-10 min, and LMO-30 min are 128.01, 125.42, 127.52, and 130.144 mA h gLMO\u22121 at 0.3C and 55 \u00b0C, respectively. Fig. S3b\u2020 displays the cycling performances of all samples measured with the bare LMO and PVDF@LGLZNO fibrous film coated LMO half-cells at 0.3C and 55 \u00b0C. The discharge capacity of bare LMO sharply fades to 11 mA h gLMO\u22121 (9% capacity retention) after 100 cycles, while those of PLMO-10 min, LMO-10 min, and LMO-30 min were 15, 38, and 110 mA h gLMO\u22121 after 100 cycles at 55 \u00b0C and 0.3C, corresponding to capacity retentions of 12.20%, 30.14%, and 83.29%, respectively. Also, the cycling performance of the cell with LMO-50 min at 55 \u00b0C and 0.3C is depicted in Fig. S3c.\u2020 The above results indicate that LMO-30 min demonstrates better cycling performance at 55 \u00b0C compared to other cells, while the bare and PLMO coated cathodes have poor resistance to elevated temperature. The corresponding cells degrade faster than they did at 25 \u00b0C as seen in Fig. 2b. The effect of coating on capacity retention at 25 \u00b0C and 55 \u00b0C is apparent. The optimized PVDF@LGLZNO fibrous film coated on the surface of the LMO electrode acts as a better protective film that could substantially decrease manganese dissolution at high temperatures and minimize the adverse effects caused by electrolyte decomposition.", "question": "What's the electrolyte?", "answer": "LMO ", "answer_start": 1552}
{"document_id": 75414, "context": "Likewise, the cycling performances of bare and coated LMO cathodes were compared using a half-cell (Li|LMO). The cycling performance of the Li|LMO half-cell was examined within the voltage range of 3.3to 4.5 V at 55 \u00b0C. The charge and discharge voltage profiles of the bare LMO and surface modified LMO samples (PLMO-10 min, LMO-10 min, and LMO-30 min) are presented in Fig. S3a.\u2020 The initial discharge capacity of bare LMO, PLMO-10 min, LMO-10 min, and LMO-30 min are 128.01, 125.42, 127.52, and 130.144 mA h gLMO\u22121 at 0.3C and 55 \u00b0C, respectively. Fig. S3b\u2020 displays the cycling performances of all samples measured with the bare LMO and PVDF@LGLZNO fibrous film coated LMO half-cells at 0.3C and 55 \u00b0C. The discharge capacity of bare LMO sharply fades to 11 mA h gLMO\u22121 (9% capacity retention) after 100 cycles, while those of PLMO-10 min, LMO-10 min, and LMO-30 min were 15, 38, and 110 mA h gLMO\u22121 after 100 cycles at 55 \u00b0C and 0.3C, corresponding to capacity retentions of 12.20%, 30.14%, and 83.29%, respectively. Also, the cycling performance of the cell with LMO-50 min at 55 \u00b0C and 0.3C is depicted in Fig. S3c.\u2020 The above results indicate that LMO-30 min demonstrates better cycling performance at 55 \u00b0C compared to other cells, while the bare and PLMO coated cathodes have poor resistance to elevated temperature. The corresponding cells degrade faster than they did at 25 \u00b0C as seen in Fig. 2b. The effect of coating on capacity retention at 25 \u00b0C and 55 \u00b0C is apparent. The optimized PVDF@LGLZNO fibrous film coated on the surface of the LMO electrode acts as a better protective film that could substantially decrease manganese dissolution at high temperatures and minimize the adverse effects caused by electrolyte decomposition.", "question": "What's the cathode?", "answer": "PLMO coated", "answer_start": 1259}
{"document_id": 75416, "context": "All the electrochemical measurements were carried out on a CHI 660E electrochemical workstation with a standard three-electrode system in 0.5 M aqueous urea solution, and 1 M KOH solution with or without 0.5 M urea at room temperature. A mercury oxide electrode (Hg/HgO), platinum electrode (Pt), and the prepared materials were used as the reference electrode, the counter electrode, and the working electrode, respectively. The mass loading of the catalysts on the nickel foam is 1.5 mg cm\u22122. And the amount of commercial Pt/C and IrO2 on NF is the same as the loading of MoP@NiCo-LDH/NF-20. The two-electrode electrolyser uses a 007-2H exchangeable membrane electrolytic cell (50 mL) with Nafion 117 as the diaphragm. The synthesized catalysts were used as the cathode and anode electrodes with a distance of 5 cm between the two electrodes. During the test, the anode was connected to the working electrode and the cathode was connected to the counter and reference electrodes. Current densities were calculated based on the geometric area. All potential values were measured on an Hg/HgO electrode and converted to reversible hydrogen potential (RHE) according to the following equation: E (V vs. RHE) = E (V vs. Hg/HgO) + 0.059pH + 0.098 V.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75416, "context": "All the electrochemical measurements were carried out on a CHI 660E electrochemical workstation with a standard three-electrode system in 0.5 M aqueous urea solution, and 1 M KOH solution with or without 0.5 M urea at room temperature. A mercury oxide electrode (Hg/HgO), platinum electrode (Pt), and the prepared materials were used as the reference electrode, the counter electrode, and the working electrode, respectively. The mass loading of the catalysts on the nickel foam is 1.5 mg cm\u22122. And the amount of commercial Pt/C and IrO2 on NF is the same as the loading of MoP@NiCo-LDH/NF-20. The two-electrode electrolyser uses a 007-2H exchangeable membrane electrolytic cell (50 mL) with Nafion 117 as the diaphragm. The synthesized catalysts were used as the cathode and anode electrodes with a distance of 5 cm between the two electrodes. During the test, the anode was connected to the working electrode and the cathode was connected to the counter and reference electrodes. Current densities were calculated based on the geometric area. All potential values were measured on an Hg/HgO electrode and converted to reversible hydrogen potential (RHE) according to the following equation: E (V vs. RHE) = E (V vs. Hg/HgO) + 0.059pH + 0.098 V.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75420, "context": "To investigate the electrochemical Na ion storage mechanism on the Na[Ni0.5Mn0.5]O2 and Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathodes upon Na ion extraction/insertion, cyclic voltammetry was performed (Fig. S7\u2020). Both cathodes underwent a series of phase transitions (O3hex. \u2192 O\u20323mon. \u2192 P3hex. \u2192 P\u20323mon. \u2192 \u2192 ). The intensity of the redox peaks of the Na[Ni0.5Mn0.5]O2 cathode, especially during the hexagonal O3\u2032\u2013hexagonal O3\u2032\u2032 phase transition, became gradually polarized and reduced in height with cycling, indicating high capacity fading continuously with structural degradation. In comparison, the redox peaks of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode hardly changed, which is consistent with the excellent Na intercalation stability of the cathode. In addition, ex situ X-ray absorption near edge structure (XANES) analysis was conducted (Fig. 3a and S8\u2020) to examine the oxidation state of transition metals during the charge\u2013discharge process. For both cathodes in the as-prepared state, Ni and Mn were divalent (2+) and tetravalent (4+), respectively. The Ni K-edge absorption spectrum clearly shifted toward the higher energy region after charging at 4.3 V, indicating that a change in the oxidation state of nickel from the divalent state to the tetravalent state occurred due to electrochemical oxidation in the Na cell. In comparison, although a shape change of the white line was observed, which is associated with a local geometry change due to the redox reaction of the surrounding electrochemically active metals, no significant edge shift was observed at the Mn K-edge, suggesting that manganese ions are electrochemically inactive in the tetravalent state, which is consistent with other previous reports. On discharge, the average oxidation state of Ni returned to its original value. Furthermore, this reaction mechanism was also confirmed through prediction of the net magnetic moments on Mn and Ni ions of Nax[Ni0.5Mn0.5]O2 based on first-principles calculations. As presented in Fig. S9,\u2020 in the case of O3-Na1[Ni0.5Mn0.5]O2, the integrated spin moments of Ni and Mn atoms were approximately 0 and +3, respectively, which indicates the existence of Ni2+ and Mn4+ ions in O3-Na1[Ni0.5Mn0.5]O2. During 1 mol Na+ extraction from the structure, the integrated spin moment of the Mn atoms remained unaltered and that of the Ni atom gradually increased from 0 to +2, which indicates the Ni2+/Ni4+ redox reaction of O3-Na1[Ni0.5Mn0.5]O2 during Na ion extraction/insertion. This prediction is consistent with the experimental results based on the XANES analysis. These results suggest that 0.01 mol of Ca2+ ions was successfully incorporated into the Na layer rather than a transition metal layer without interrupting the charge-transfer reaction.", "question": "What's the cathode?", "answer": "Na[Ni0.5Mn0.5]O2", "answer_start": 67}
{"document_id": 75420, "context": "To investigate the electrochemical Na ion storage mechanism on the Na[Ni0.5Mn0.5]O2 and Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathodes upon Na ion extraction/insertion, cyclic voltammetry was performed (Fig. S7\u2020). Both cathodes underwent a series of phase transitions (O3hex. \u2192 O\u20323mon. \u2192 P3hex. \u2192 P\u20323mon. \u2192 \u2192 ). The intensity of the redox peaks of the Na[Ni0.5Mn0.5]O2 cathode, especially during the hexagonal O3\u2032\u2013hexagonal O3\u2032\u2032 phase transition, became gradually polarized and reduced in height with cycling, indicating high capacity fading continuously with structural degradation. In comparison, the redox peaks of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode hardly changed, which is consistent with the excellent Na intercalation stability of the cathode. In addition, ex situ X-ray absorption near edge structure (XANES) analysis was conducted (Fig. 3a and S8\u2020) to examine the oxidation state of transition metals during the charge\u2013discharge process. For both cathodes in the as-prepared state, Ni and Mn were divalent (2+) and tetravalent (4+), respectively. The Ni K-edge absorption spectrum clearly shifted toward the higher energy region after charging at 4.3 V, indicating that a change in the oxidation state of nickel from the divalent state to the tetravalent state occurred due to electrochemical oxidation in the Na cell. In comparison, although a shape change of the white line was observed, which is associated with a local geometry change due to the redox reaction of the surrounding electrochemically active metals, no significant edge shift was observed at the Mn K-edge, suggesting that manganese ions are electrochemically inactive in the tetravalent state, which is consistent with other previous reports. On discharge, the average oxidation state of Ni returned to its original value. Furthermore, this reaction mechanism was also confirmed through prediction of the net magnetic moments on Mn and Ni ions of Nax[Ni0.5Mn0.5]O2 based on first-principles calculations. As presented in Fig. S9,\u2020 in the case of O3-Na1[Ni0.5Mn0.5]O2, the integrated spin moments of Ni and Mn atoms were approximately 0 and +3, respectively, which indicates the existence of Ni2+ and Mn4+ ions in O3-Na1[Ni0.5Mn0.5]O2. During 1 mol Na+ extraction from the structure, the integrated spin moment of the Mn atoms remained unaltered and that of the Ni atom gradually increased from 0 to +2, which indicates the Ni2+/Ni4+ redox reaction of O3-Na1[Ni0.5Mn0.5]O2 during Na ion extraction/insertion. This prediction is consistent with the experimental results based on the XANES analysis. These results suggest that 0.01 mol of Ca2+ ions was successfully incorporated into the Na layer rather than a transition metal layer without interrupting the charge-transfer reaction.", "question": "What's the cathode?", "answer": "Na0.98Ca0.01[Ni0.5Mn0.5]O2", "answer_start": 88}
{"document_id": 75427, "context": "As the key component in HZBs, cathodes work as the electroactive materials in rechargeable Zn-ion batteries and the catalyst in Zn\u2013air batteries. They link both electrochemical reactions at the same time and have attracted great interest. Lee et al. initially prepared NiO/Ni(OH)2 nanoflakes on carbon paper as cathodes for HZBs, which opens the door for hybrid zinc systems. M. Ni's group and Zhi's group prepared Co3O4 nanosheets on carbon cloth to fabricate a Zn\u2013Co3O4/air hybrid battery. Wang et al. constructed NiCo2S4 nanotubes on an N-doped carbon network derived from filter paper and fabricated a Zn\u2013NiCo2S4/air hybrid battery with high capacity. Li et al. used NiCo2O4 nanorod@carbon coated nickel foam as the cathode to build a hybrid battery which exhibited good stability. Tan et al. prepared a Zn\u2013Ag/air hybrid battery and achieved good reversibility and stability. Very recently, Zhi's group reported Ni3S2 nanosheets on Ni foam as a high-performance HZB cathode. Although rapid developments have been made for HZBs, defects such as slow oxygen reduction/evolution reactions (ORR/OER) and inferior energy storage properties still limit their practical applications. Therefore, it is still a crucial issue to explore novel cathode candidates for HZBs to realize both high efficiency and high energy storage properties at the same time.", "question": "What's the cathode?", "answer": "NiCo2O4 nanorod@carbon coated nickel foam", "answer_start": 671}
{"document_id": 75427, "context": "As the key component in HZBs, cathodes work as the electroactive materials in rechargeable Zn-ion batteries and the catalyst in Zn\u2013air batteries. They link both electrochemical reactions at the same time and have attracted great interest. Lee et al. initially prepared NiO/Ni(OH)2 nanoflakes on carbon paper as cathodes for HZBs, which opens the door for hybrid zinc systems. M. Ni's group and Zhi's group prepared Co3O4 nanosheets on carbon cloth to fabricate a Zn\u2013Co3O4/air hybrid battery. Wang et al. constructed NiCo2S4 nanotubes on an N-doped carbon network derived from filter paper and fabricated a Zn\u2013NiCo2S4/air hybrid battery with high capacity. Li et al. used NiCo2O4 nanorod@carbon coated nickel foam as the cathode to build a hybrid battery which exhibited good stability. Tan et al. prepared a Zn\u2013Ag/air hybrid battery and achieved good reversibility and stability. Very recently, Zhi's group reported Ni3S2 nanosheets on Ni foam as a high-performance HZB cathode. Although rapid developments have been made for HZBs, defects such as slow oxygen reduction/evolution reactions (ORR/OER) and inferior energy storage properties still limit their practical applications. Therefore, it is still a crucial issue to explore novel cathode candidates for HZBs to realize both high efficiency and high energy storage properties at the same time.", "question": "What's the cathode?", "answer": "Ni3S2 nanosheets on Ni foam", "answer_start": 916}
{"document_id": 75428, "context": "In summary, we have reported a facile strategy for preparing Pt3Ni1/NixFe LDHs as a binder-free catalytic electrode for HSABs. The HSAB with the Pt3Ni1/NixFe LDHs cathode delivered a higher open circle potential of 2.98 V and a lower \u0394V of 0.50 V, together with remarkable cycling stability and excellent rechargeability with an average high round-trip efficiency of 79.9% during 350 cycles, which outperforms the HSABs assembled with the commercial catalyst composed of 20% Pt/C and RuO2. The remarkable charge\u2013discharge performance and long-term cycling stability are mainly ascribed to the following: (1) the abundant Ni2+ vacancies alter the surface electronic structure of NiFe LDHs, which promotes electron/ion transfer kinetics and induces the strong interactions with PtNi nanoalloys. (2) The uniformly dispersed ultrafine PtNi nanoparticles on Pt3Ni1/NixFe LDHs enhance the electronic conductivity and provide abundant catalytic active sites, thus greatly boosting the ORR and OER in an alkaline medium. (3) The 3D hierarchically porous architectures of Pt3Ni1/NixFe LDHs offer high integrity and durability, high accessibility for electroactive sites, and enhance the interfacial kinetics that facilitates media transfer, as well as prevent catalytic by-product aggregation. (4) The binder-free design is conducive to exposing more active sites, leading to good catalytic performance. Thus, we believe that the discovery of the bifunctional Pt3Ni1/NixFe LDHs electrocatalyst sheds new light on the rational design of high-performance binder-free catalytic electrodes for large-scale application in energy conversion and storage.", "question": "What's the cathode?", "answer": "Pt3Ni1/NixFe LDHs", "answer_start": 145}
{"document_id": 75430, "context": "Lithium manganese oxide (LMO) is one of the most promising cathode materials for lithium-ion batteries. However, the dissolution of manganese and its deposition on the anode surface cause poor cycling stability. To alleviate these issues, a film composed of polyvinylidene difluoride (PVDF) and Li5.6Ga0.26La2.9Zr1.87Nb0.05O12 type garnet (PVDF@LGLZNO) is coated directly on the LMO electrode and it functions as a promising artificial cathode\u2013electrolyte interphase (CEI). The film thickness is optimized taking into account the electrospinning\u2013processing time. To realize a cell with good capacity retention, excellent rate capability and resilience under harsher conditions (e.g. elevated temperature or high rates), the coated LMO cathode is coupled with a new anode which consists of sulfurized carbon derived from polyacrylonitrile (S-C(PAN)). The electrode (LMO-30 min) coated with the PVDF@LGLZNO composite material shows outstanding cycling stability and rate capability, as well as capacity retention when compared to the bare electrode both at room temperature (25 \u00b0C) and elevated temperature (55 \u00b0C). The PVDF@LGLZNO fibrous film coating suppresses the dissolution of manganese both at high C-rates and 55 \u00b0C, as supported by XPS, whereas PVDF coated and bare LMO cathodes are not able to prevent further deterioration of themselves. The film significantly minimizes undesirable side reactions at the cathode\u2013electrolyte interface and reduces charge transfer resistance. The new cell with PVDF@LGLZNO (LMO-30 min) modified cathode and S-C(PAN) anode delivers capacity retention of 77% after 1000 cycles at 1C, corresponding to an average capacity decay of 0.023% per cycle.", "question": "What's the cathode?", "answer": "Lithium manganese oxide (LMO)", "answer_start": 0}
{"document_id": 75430, "context": "Lithium manganese oxide (LMO) is one of the most promising cathode materials for lithium-ion batteries. However, the dissolution of manganese and its deposition on the anode surface cause poor cycling stability. To alleviate these issues, a film composed of polyvinylidene difluoride (PVDF) and Li5.6Ga0.26La2.9Zr1.87Nb0.05O12 type garnet (PVDF@LGLZNO) is coated directly on the LMO electrode and it functions as a promising artificial cathode\u2013electrolyte interphase (CEI). The film thickness is optimized taking into account the electrospinning\u2013processing time. To realize a cell with good capacity retention, excellent rate capability and resilience under harsher conditions (e.g. elevated temperature or high rates), the coated LMO cathode is coupled with a new anode which consists of sulfurized carbon derived from polyacrylonitrile (S-C(PAN)). The electrode (LMO-30 min) coated with the PVDF@LGLZNO composite material shows outstanding cycling stability and rate capability, as well as capacity retention when compared to the bare electrode both at room temperature (25 \u00b0C) and elevated temperature (55 \u00b0C). The PVDF@LGLZNO fibrous film coating suppresses the dissolution of manganese both at high C-rates and 55 \u00b0C, as supported by XPS, whereas PVDF coated and bare LMO cathodes are not able to prevent further deterioration of themselves. The film significantly minimizes undesirable side reactions at the cathode\u2013electrolyte interface and reduces charge transfer resistance. The new cell with PVDF@LGLZNO (LMO-30 min) modified cathode and S-C(PAN) anode delivers capacity retention of 77% after 1000 cycles at 1C, corresponding to an average capacity decay of 0.023% per cycle.", "question": "What's the anode?", "answer": " S-C(PAN) ", "answer_start": 1547}
{"document_id": 75431, "context": "In view of the bifunctional catalytic performance of MoP@NiCo-LDH/NF-20 towards both UOR and HER, the material was used as both anode and cathode to form a two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20). Fig. 7a shows the LSV curves of electrolysis cell voltages for both water and water with urea. At 100 mA cm\u22122, urea\u2013water electrolysis (UOR & HER) requires much less driving voltage (1.405 V) than pure water electrolysis (OER & HER) (1.697 V). The inset of Fig. 7a illustrates a histogram of the driving voltages required at 20, 40, 60, and 100 mA cm\u22122. It can be seen intuitively that the driving voltage required by urea auxiliary electrolysis is smaller than that required by pure water electrolysis no matter whether the current density is low or high. Fig. 7b shows the polarization curves of the MoP/NF\u2016MoP/NF, NiCo-LDH/NF\u2016NiCo-LDH/NF, MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20, and Pt/C/NF\u2016IrO2/NF electrolysis cells in 1 M KOH with 0.5 M urea. At 100 mA cm\u22122, the cell voltages of MoP/NF\u2016MoP/NF, NiCo-LDH/NF\u2016NiCo-LDH/NF, MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20, and Pt/C/NF\u2016IrO2/NF are 1.494, 1.579, 1.405, and 1.708 V, respectively (Table S1\u2020). The results show that at the same current density, the driving cell voltage of MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20 is the lowest among all four cells. The significant bifunctional catalytic activity of MoP@NiCo-LDH/NF-20 exceeds those of reported non-precious metal catalysts (Table S2\u2020).", "question": "What's the cathode?", "answer": " MoP@NiCo-LDH/NF-20", "answer_start": 52}
{"document_id": 75431, "context": "In view of the bifunctional catalytic performance of MoP@NiCo-LDH/NF-20 towards both UOR and HER, the material was used as both anode and cathode to form a two-electrode electrolyser (MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20). Fig. 7a shows the LSV curves of electrolysis cell voltages for both water and water with urea. At 100 mA cm\u22122, urea\u2013water electrolysis (UOR & HER) requires much less driving voltage (1.405 V) than pure water electrolysis (OER & HER) (1.697 V). The inset of Fig. 7a illustrates a histogram of the driving voltages required at 20, 40, 60, and 100 mA cm\u22122. It can be seen intuitively that the driving voltage required by urea auxiliary electrolysis is smaller than that required by pure water electrolysis no matter whether the current density is low or high. Fig. 7b shows the polarization curves of the MoP/NF\u2016MoP/NF, NiCo-LDH/NF\u2016NiCo-LDH/NF, MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20, and Pt/C/NF\u2016IrO2/NF electrolysis cells in 1 M KOH with 0.5 M urea. At 100 mA cm\u22122, the cell voltages of MoP/NF\u2016MoP/NF, NiCo-LDH/NF\u2016NiCo-LDH/NF, MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20, and Pt/C/NF\u2016IrO2/NF are 1.494, 1.579, 1.405, and 1.708 V, respectively (Table S1\u2020). The results show that at the same current density, the driving cell voltage of MoP@NiCo-LDH/NF-20\u2016MoP@NiCo-LDH/NF-20 is the lowest among all four cells. The significant bifunctional catalytic activity of MoP@NiCo-LDH/NF-20 exceeds those of reported non-precious metal catalysts (Table S2\u2020).", "question": "What's the anode?", "answer": " MoP@NiCo-LDH/NF-20", "answer_start": 52}
{"document_id": 75458, "context": "Ni-rich layered cathode materials are at the forefront to be deployed in high energy density Li-ion batteries for the automotive market. However, the intrinsic poor structural and interfacial stability during overcharging could trigger violent thermal failure, which severely limits their wide application. To protect the Ni-rich cathode from overcharging, we firstly report a redox-active cation, thioether-substituted diaminocyclopropenium, as an electrolyte additive to limit the cell voltage within the safe value during overcharging. The organic cation demonstrates a record-breaking electrochemical reversibility at \u223c4.55 V versus Li+/Li and solubility (0.5 M) in carbonate-based electrolyte. The protection capability of the additive was explored in two cell chemistries: a LiNi0.8Co0.15Al0.05O2/graphite cell and a LiNi0.8Co0.15Al0.05O2/silicon\u2013graphene cell with areal capacities of \u223c2.2 mA h cm\u22122 and \u223c3 mA h cm\u22122, respectively. With 0.2 M addition, the LiNi0.8Co0.15Al0.05O2/graphite cell survived 54 cycles at 0.2C with 100% overcharge. Moreover, the cell can carry an utmost 4.4 mA cm\u22122 (2C) with 100% overcharge and a maximum capacity of 7540% SOC at 0.2C.", "question": "What's the cathode?", "answer": "Ni-rich layered", "answer_start": 0}
{"document_id": 75458, "context": "Ni-rich layered cathode materials are at the forefront to be deployed in high energy density Li-ion batteries for the automotive market. However, the intrinsic poor structural and interfacial stability during overcharging could trigger violent thermal failure, which severely limits their wide application. To protect the Ni-rich cathode from overcharging, we firstly report a redox-active cation, thioether-substituted diaminocyclopropenium, as an electrolyte additive to limit the cell voltage within the safe value during overcharging. The organic cation demonstrates a record-breaking electrochemical reversibility at \u223c4.55 V versus Li+/Li and solubility (0.5 M) in carbonate-based electrolyte. The protection capability of the additive was explored in two cell chemistries: a LiNi0.8Co0.15Al0.05O2/graphite cell and a LiNi0.8Co0.15Al0.05O2/silicon\u2013graphene cell with areal capacities of \u223c2.2 mA h cm\u22122 and \u223c3 mA h cm\u22122, respectively. With 0.2 M addition, the LiNi0.8Co0.15Al0.05O2/graphite cell survived 54 cycles at 0.2C with 100% overcharge. Moreover, the cell can carry an utmost 4.4 mA cm\u22122 (2C) with 100% overcharge and a maximum capacity of 7540% SOC at 0.2C.", "question": "What's the cathode?", "answer": "Ni-rich", "answer_start": 322}
{"document_id": 75583, "context": "The non-renewability of fossil energy and growing environmental pollution have spurred the development of sustainable energy technologies, such as fuel cells and metal\u2013air batteries. Of these, zinc\u2013air batteries represent a promising energy technology for next-generation portable electronics, due to their good rechargeability and high theoretical density (1370 W h kg\u22121), where the device performance is largely dictated by the reversible catalysts at the cathode for oxygen reduction (ORR) and oxygen evolution reactions (OER). Platinum-based nanoparticles have been the catalysts of choice for ORR, whereas Ir and Ru-based nanoparticles for OER. Yet their high costs and low natural abundance have hindered the practical applications of the technology. Thus, development of low-cost and high-performance electrocatalysts for ORR and OER have been attracting extensive interest. Recent reports have shown that atomically dispersed metals (such as Mn, Fe and Co) within nitrogen-doped carbons, exhibit excellent electrocatalytic performance towards ORR and may even surpass the corresponding nanoparticle counterparts. In both experimental and theoretical studies, Fe single atom catalysts (SACs) have been recognized as the most active catalysts towards ORR in alkaline media. Unfortunately, for the Fe-based SACs, Fenton reaction involving the Fe center and ORR byproduct H2O2 produces hydroxyl and oxygen radicals, which not only affect the durability of the catalysts by changing its chemical structure, but also damage the battery devices by corroding the ion membranes. Additionally, theoretical and experimental studies have shown that the Fe-based SACs performs poorly towards OER, as compared to other 3d transition metals, such as Co and Ni. Therefore, it is critical to improve the ORR durability and OER activity of Fe SACs such that they may be used as bifunctional oxygen catalysts in rechargeable Zn\u2013air battery. Towards this end, the incorporation of Co atomic sites into Fe SACs represents a unique strategy. First of all, the weak Fenton activity between Co and H2O2 is anticipated to markedly enhance the ORR stability of Fe SACs. In addition, prior studies have shown that Co-doped carbon exhibits a low overpotential and small Tafel slope towards OER. Thus, it is envisioned that atomically dispersing Co atoms into Fe-doped carbon may achieve a bimetal catalyst with excellent ORR/OER activity and enhanced durability, in comparison to the monometal counterparts.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75586, "context": "Metal sulfides having various micro-/nanostructures and compositions (Fig. 2), such as spherical/non-spherical hollow materials, high surface area/porosity/selectivity structures, hierarchical carbon-based hybrids, and unique functional materials, have been successfully prepared in recent years through various synthetic approaches. These material systems offer the possibility to study the influence of these features on the electrochemical properties of Li\u2013S batteries. Generally, there are two typical strategies to building metal sulfides and sulfur cathode composites: (i) one-step in situ fabrication and (ii) stepwise synthesis, which often involves injection of sulfur into a host via melt/solution-diffusion methods. Synthetic strategies involving the use of metal sulfides to protect Li anodes, modify separators, and engineer interlayers, are more flexible than those related to the use of metal sulfides and sulfur cathode composites, owing to the removal of the sulfur injection process. We consider the fundamental challenges facing Li\u2013S batteries and discuss synthetic strategies to highlight their attractive features. Accordingly, the methods can be broadly categorized into five groups: (i) building buffer space to accommodate volume fluctuations; (ii) enhancing the binding ability for LiPSs; (iii) improving the electronic conductivity of the active material; (iv) increasing the sulfur loading; and (v) designing other specialized functions.", "question": "What's the cathode?", "answer": "sulfur ", "answer_start": 548}
{"document_id": 75586, "context": "Metal sulfides having various micro-/nanostructures and compositions (Fig. 2), such as spherical/non-spherical hollow materials, high surface area/porosity/selectivity structures, hierarchical carbon-based hybrids, and unique functional materials, have been successfully prepared in recent years through various synthetic approaches. These material systems offer the possibility to study the influence of these features on the electrochemical properties of Li\u2013S batteries. Generally, there are two typical strategies to building metal sulfides and sulfur cathode composites: (i) one-step in situ fabrication and (ii) stepwise synthesis, which often involves injection of sulfur into a host via melt/solution-diffusion methods. Synthetic strategies involving the use of metal sulfides to protect Li anodes, modify separators, and engineer interlayers, are more flexible than those related to the use of metal sulfides and sulfur cathode composites, owing to the removal of the sulfur injection process. We consider the fundamental challenges facing Li\u2013S batteries and discuss synthetic strategies to highlight their attractive features. Accordingly, the methods can be broadly categorized into five groups: (i) building buffer space to accommodate volume fluctuations; (ii) enhancing the binding ability for LiPSs; (iii) improving the electronic conductivity of the active material; (iv) increasing the sulfur loading; and (v) designing other specialized functions.", "question": "What's the anode?", "answer": "Li", "answer_start": 795}
{"document_id": 75586, "context": "Metal sulfides having various micro-/nanostructures and compositions (Fig. 2), such as spherical/non-spherical hollow materials, high surface area/porosity/selectivity structures, hierarchical carbon-based hybrids, and unique functional materials, have been successfully prepared in recent years through various synthetic approaches. These material systems offer the possibility to study the influence of these features on the electrochemical properties of Li\u2013S batteries. Generally, there are two typical strategies to building metal sulfides and sulfur cathode composites: (i) one-step in situ fabrication and (ii) stepwise synthesis, which often involves injection of sulfur into a host via melt/solution-diffusion methods. Synthetic strategies involving the use of metal sulfides to protect Li anodes, modify separators, and engineer interlayers, are more flexible than those related to the use of metal sulfides and sulfur cathode composites, owing to the removal of the sulfur injection process. We consider the fundamental challenges facing Li\u2013S batteries and discuss synthetic strategies to highlight their attractive features. Accordingly, the methods can be broadly categorized into five groups: (i) building buffer space to accommodate volume fluctuations; (ii) enhancing the binding ability for LiPSs; (iii) improving the electronic conductivity of the active material; (iv) increasing the sulfur loading; and (v) designing other specialized functions.", "question": "What's the cathode?", "answer": "sulfur ", "answer_start": 921}
{"document_id": 75594, "context": "Based on the above theory, the self-charging process of the flexible SSCFB was illustrated as follows (Fig. 7). In the initial stage, the device suffers from no external strains/deformations and an electrochemical equilibrium state is present (Fig. 7a). In the second stage, external strains/deformations are applied on the device, and the piezoelectric gel-electrolyte in the device generates a piezoelectric field with a positive potential close to the cathode and negative potential around the anode (Fig. 7b). As a result, Na+ migration is carried out through the piezoelectric gel-electrolyte from the cathode to the anode, followed by a charging reaction in the device (cathode: Na3V2(PO4)3 \u2192 NaV2(PO4)3 + 2Na+ + 2e\u2212; anode: xC + 2Na+ + 2e\u2212 \u2192 Na2Cx) (Fig. 7c). Impressively, when the external force is removed, the piezoelectric field doesn't disappear immediately, and the self-charging process can proceed by virtue of the internal residual strains (Fig. 7d). Once the piezoelectric potential is balanced by the re-distribution of Na+, a new equilibrium of the electrodes is formed (Fig. 7e). Finally, the piezoelectric field disappears along with the complete loss of residual strain, and a reverse migration of Na+ to the original position is conducted (Fig. 7f). Once the external force is applied on the device again, the self-charging process can be repeated.", "question": "What's the cathode?", "answer": "Na3V2(PO4)3", "answer_start": 685}
{"document_id": 75594, "context": "Based on the above theory, the self-charging process of the flexible SSCFB was illustrated as follows (Fig. 7). In the initial stage, the device suffers from no external strains/deformations and an electrochemical equilibrium state is present (Fig. 7a). In the second stage, external strains/deformations are applied on the device, and the piezoelectric gel-electrolyte in the device generates a piezoelectric field with a positive potential close to the cathode and negative potential around the anode (Fig. 7b). As a result, Na+ migration is carried out through the piezoelectric gel-electrolyte from the cathode to the anode, followed by a charging reaction in the device (cathode: Na3V2(PO4)3 \u2192 NaV2(PO4)3 + 2Na+ + 2e\u2212; anode: xC + 2Na+ + 2e\u2212 \u2192 Na2Cx) (Fig. 7c). Impressively, when the external force is removed, the piezoelectric field doesn't disappear immediately, and the self-charging process can proceed by virtue of the internal residual strains (Fig. 7d). Once the piezoelectric potential is balanced by the re-distribution of Na+, a new equilibrium of the electrodes is formed (Fig. 7e). Finally, the piezoelectric field disappears along with the complete loss of residual strain, and a reverse migration of Na+ to the original position is conducted (Fig. 7f). Once the external force is applied on the device again, the self-charging process can be repeated.", "question": "What's the anode?", "answer": "C ", "answer_start": 732}
{"document_id": 75598, "context": "A superfast and stable ssZIB based on a CNF\u2013PAM hydrogel electrolyte and a Mg0.23V2O5\u00b71.0H2O cathode was successfully developed from this work. The designed CNF\u2013PAM hydrogel shows high stretchability and robust mechanical stability. Moreover, the porous CNF\u2013PAM hydrogel electrolyte provides efficient pathways for the transportation of zinc ions. And the robust layered structure of V2O5\u00b71.0H2O pillared with Mg2+ ions and water supports the fast insertion/extraction of zinc ions in the lattice. The prepared ssZIB shows remarkably high rate capability and long-term cycling performance. At a high current density of 5 A g\u22121, the ssZIB provides a high specific capacity of about 216 mA h g\u22121 within a charging time of only three minutes for over 2000 cycles, maintaining 98.6% of the initial capacity. Furthermore, with the designed CNF\u2013PAM hydrogel electrolyte, a spring ssZIB was also obtained. The spring ssZIB is still working under repeated stretching. Even under some critical states, such as repeated bending, freezing, and heating, the ssZIB shows high stability and reliability. The ssZIB shows extraordinary electrochemical performance, robust stability, and high stretchability, which helps bring new opportunities for using ZIBs in practical large-scale storage devices.", "question": "What's the cathode?", "answer": "Mg0.23V2O5\u00b71.0H2O", "answer_start": 75}
{"document_id": 75598, "context": "A superfast and stable ssZIB based on a CNF\u2013PAM hydrogel electrolyte and a Mg0.23V2O5\u00b71.0H2O cathode was successfully developed from this work. The designed CNF\u2013PAM hydrogel shows high stretchability and robust mechanical stability. Moreover, the porous CNF\u2013PAM hydrogel electrolyte provides efficient pathways for the transportation of zinc ions. And the robust layered structure of V2O5\u00b71.0H2O pillared with Mg2+ ions and water supports the fast insertion/extraction of zinc ions in the lattice. The prepared ssZIB shows remarkably high rate capability and long-term cycling performance. At a high current density of 5 A g\u22121, the ssZIB provides a high specific capacity of about 216 mA h g\u22121 within a charging time of only three minutes for over 2000 cycles, maintaining 98.6% of the initial capacity. Furthermore, with the designed CNF\u2013PAM hydrogel electrolyte, a spring ssZIB was also obtained. The spring ssZIB is still working under repeated stretching. Even under some critical states, such as repeated bending, freezing, and heating, the ssZIB shows high stability and reliability. The ssZIB shows extraordinary electrochemical performance, robust stability, and high stretchability, which helps bring new opportunities for using ZIBs in practical large-scale storage devices.", "question": "What's the electrolyte?", "answer": "CNF\u2013PAM hydrogel", "answer_start": 40}
{"document_id": 75599, "context": "Several routes can be envisaged to improve the mechanical response of the composite cathode, none of which is likely to be very easy. This includes the optimization of cathode morphology, cathode chemistry/structure, mechanical properties of the solid electrolyte, and use of external pressure. Reducing the cathode surface displacement is critical for lowering the mechanical strain during cycling, which can be achieved by decreasing the cathode particle size or cathode strain. For a cathode material with a specific strain, a smaller particle size would result in less surface displacement and therefore reduced stress at the cathode/solid electrolyte interface. However, reducing the cathode particle size could negatively affect the cathode utilization and energy density of SSBs. Reducing the cathode strain during cycling is another way to minimize mechanical issues. Different cathode chemistries and structures have been shown to lead to different volume change during cycling. The current results motivate the search for high-energy-density electrode materials with small volume change or \u201czero-strain\u201d. Different solid-electrolyte materials will also result in different mechanical degradation behavior. For example, the rapid development of cracks in the first few cycles was observed in SSBs with an oxide-based solid electrolyte, which is more rigid than the sulfide solid electrolyte used in the current study. In contrast, polymer-based composite solid electrolytes can accommodate larger strain and have been shown to improve the cycling stability. Therefore, developing a solid electrolyte with higher elasticity is an additional route to mitigate mechanical instability. Finally, applying a large external pressure (stack pressure) during cycling could in principle reduce the contact loss at the cathode/solid electrolyte interface, but such a large stack pressure may not be practical for large format cells.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75601, "context": "Recent studies have suggested that Co-free, Ni-rich layered cathodes (e.g., doped LiNiO2) can provide promising battery performance for practical applications. However, these layered cathodes suffer from significant surface instability during various stages of the sample history, which generates inherent challenges for achieving stable battery performance and obtaining statistically representative characterization results. To reliably report the surface chemistry of these materials, delicate controls of stepwise sample preparation are required. In this study, we aim to illustrate how the surface chemistry of LiNiO2 based materials changes with various environments, including human exhalation, sample storage, sample preparation, electrochemical cycling, and surface doping. Our results demonstrate that the surface of these materials is highly reactive and prone to alter at various stages of sample handling and characterization. The sensitive surface could impact the interpretation of the surface chemical and structural information, including surface carbonate formation, transition metal reduction and dissolution, and surface reconstruction. Importantly, the heterogeneity of the surface degradation calls for a consolidation of nanoscale, high-resolution characterization and ensemble-averaged methods in order to improve statistical representation. Furthermore, the doping chemistry can effectively mitigate the surface degradation and improve overall battery performance due to the enhanced surface oxygen retention. Our study highlights the necessity of strict measurements through complementary characterization at multiple length scales to eliminate unintentional biased conclusions.", "question": "What's the cathode?", "answer": "Co-free, Ni-rich layered ", "answer_start": 35}
{"document_id": 75602, "context": "To examine the catalytic and capture property of 1T MoS2 NDs in a working Li\u2013S cell, MoS2 ND/porous carbon/Li2S6 cathodes were prepared and subjected to synchrotron in situ XRD and in situ EIS characterizations. Fig. 4 shows the contour plot of the in situ XRD patterns collected during the first two cycles. Before discharging, no crystalline peaks were observed, confirming the high purity of the polysulfide catholyte and the low content of MoS2 NDs. When the cell was discharged to the plateau at 2.1 V, peaks referring to the (111) and (200) planes of cubic Li2S (PDF No. 023-0369, marked with a black dashed-line) appeared and reached their maximum intensity at the end of lithiation (bottom of Fig. 4). Upon charging, the intensity of Li2S decreased gradually, followed with no discernible XRD peaks and then the generation of monoclinic S8 (PDF No. 071-0137, marked with white dashed-lines), illustrating the solid (Li2S)\u2013liquid (polysulfides)\u2013solid (S8) reactions during the charging process. During the 2nd discharge/charge, reversible transitions between sulfur and Li2S were observed. When we compare the current in situ XRD results with peer studies, two findings can be extracted. First, MoS2 NDs propel the formation of Li2S crystals. Nelson et al. and Yang et al. both argued that the sluggish kinetics for solid (Li2S2)\u2013solid (Li2S) conversion prevents Li2S formation upon the full discharge of sulfur/carbon electrodes, resulting in undetectable Li2S crystals during in situ XRD studies. The incomplete reduction accounted for the deficient sulfur utilization and low reversible capacities. Fortunately, the powerful MoS2 ND catalysts enabled the reversible formation of crystalline Li2S in our operando XRD studies. Second, Ye et al. reported that the poor catalytic capability of MoN led to occasioned residual S8 XRD peaks for the MoN/sulfur electrode after full discharging, which was also observed for conventional 2H MoS2 flakes-modified porous carbon/Li2S6 cathodes in this work (Fig. S9, ESI\u2020). In contrast, no residual sulfur/Li2S crystals were observed for MoS2 ND/porous carbon/Li2S6 after full discharging/charging, respectively, again indicating the high catalytic property of the 1T MoS2 NDs.", "question": "What's the cathode?", "answer": "MoS2 ND/porous carbon/Li2S6", "answer_start": 85}
{"document_id": 75602, "context": "To examine the catalytic and capture property of 1T MoS2 NDs in a working Li\u2013S cell, MoS2 ND/porous carbon/Li2S6 cathodes were prepared and subjected to synchrotron in situ XRD and in situ EIS characterizations. Fig. 4 shows the contour plot of the in situ XRD patterns collected during the first two cycles. Before discharging, no crystalline peaks were observed, confirming the high purity of the polysulfide catholyte and the low content of MoS2 NDs. When the cell was discharged to the plateau at 2.1 V, peaks referring to the (111) and (200) planes of cubic Li2S (PDF No. 023-0369, marked with a black dashed-line) appeared and reached their maximum intensity at the end of lithiation (bottom of Fig. 4). Upon charging, the intensity of Li2S decreased gradually, followed with no discernible XRD peaks and then the generation of monoclinic S8 (PDF No. 071-0137, marked with white dashed-lines), illustrating the solid (Li2S)\u2013liquid (polysulfides)\u2013solid (S8) reactions during the charging process. During the 2nd discharge/charge, reversible transitions between sulfur and Li2S were observed. When we compare the current in situ XRD results with peer studies, two findings can be extracted. First, MoS2 NDs propel the formation of Li2S crystals. Nelson et al. and Yang et al. both argued that the sluggish kinetics for solid (Li2S2)\u2013solid (Li2S) conversion prevents Li2S formation upon the full discharge of sulfur/carbon electrodes, resulting in undetectable Li2S crystals during in situ XRD studies. The incomplete reduction accounted for the deficient sulfur utilization and low reversible capacities. Fortunately, the powerful MoS2 ND catalysts enabled the reversible formation of crystalline Li2S in our operando XRD studies. Second, Ye et al. reported that the poor catalytic capability of MoN led to occasioned residual S8 XRD peaks for the MoN/sulfur electrode after full discharging, which was also observed for conventional 2H MoS2 flakes-modified porous carbon/Li2S6 cathodes in this work (Fig. S9, ESI\u2020). In contrast, no residual sulfur/Li2S crystals were observed for MoS2 ND/porous carbon/Li2S6 after full discharging/charging, respectively, again indicating the high catalytic property of the 1T MoS2 NDs.", "question": "What's the cathode?", "answer": "porous carbon/Li2S6", "answer_start": 1962}
{"document_id": 75605, "context": "Based on eqn (12), the effective stiffness can be determined if the wave velocity and the material density are known. The wave velocity can be determined from the first arrival of the wave and cell thickness. To confirm that the measured wave velocity is accurate, calibration metals of known thicknesses and wave velocities were tested. Table 4 indicates metal foil thicknesses above 500 \u03bcm in thickness are accurately measured, whereas foil thicknesses less than 250 \u03bcm are underestimated. We attribute this error to the greater impact of the acoustic gel couplant at these lower thicknesses. The liquid gel couplant, which is necessary to induce low acoustic attenuation at the interface, is of a finite thickness and should be accounted for. Liquid gel couplant typically has a relatively lower wave velocity of around 1500 m s\u22121 (similar to water) and would therefore result in a significant underestimation of the wave velocity for thin metal foils where the couplant contributes to a greater proportion of the total propagation path. Fortunately, pouch cells are 500 \u03bcm thick at the minimum and can be accurately measured. To confirm the consistency of results regardless of battery thickness, pouch cells were constructed with n = 1 to n = 30 layers, with one layer (n = 1) being defined as: anode + separator + cathode. The subsequent layer is then: cathode (other side) + separator + anode. n = 30 is the full 210 mA h LiCoO2/graphite pouch cell, with 15 double-sided cathodes and 16 double-sided anodes. A schematic of the configuration is demonstrated in Fig. 1. In Fig. 3b, the last data point corresponds to n = 34, which was obtained from a slightly thicker commercial pouch cell of the same chemistry and configuration. The resulting thickness vs. first break (Fig. 3b) shows a linear relationship, indicating a constant wave velocity of approximately 1700 m s\u22121 and resulting in a calculated effective stiffness of 4.76 GPa (Fig. 3a). Therefore, the measured wave velocity and the resulting effective stiffness is confirmed to be the same regardless of how many repeating cell layers there are, and thicker cell stacks do not slow down the wave velocity. The measurement of 4.76 GPa is comparable to a prior ex situ study by Knehr and Hodson, where a digital caliper was used to measure the pouch cell thickness. The careful calibration and confirmatory studies here demonstrate the reliability of the acoustic measurement not only for relative shifts but also in calculating an intrinsic material stiffness.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75607, "context": "Correction for \u2018Identifying the anionic redox activity in cation-disordered Li1.25Nb0.25Fe0.50O2/C oxide cathodes for Li-ion batteries\u2019 by Mingzeng Luo et al., J. Mater. Chem. A, 2020, 8, 5115\u20135127, DOI: 10.1039/C9TA11739C.", "question": "What's the cathode?", "answer": "Li1.25Nb0.25Fe0.50O2/C oxide", "answer_start": 76}
{"document_id": 75614, "context": "5.3.2 Coexisting substrates and contaminants. The investigated substrates and contaminants for oily water separation were mainly strong electrolytes such as NaCl, HCl and NaOH. Considering these coexisting chemicals would not significantly change the surface properties of titanate, the added electrolytes were found to have no apparent effects for oil/water separation.", "question": "What's the electrolyte?", "answer": "NaCl, HCl and NaOH", "answer_start": 157}
{"document_id": 75620, "context": "Small molecules. Perylenetetracarboxylic dianhydride (PTCDA 9) was relatively widely studied in potassium batteries. It was first proposed for K-based cells by Hu et al., who tested it with a carbonate-based electrolyte. The material delivered a Qm of 130 mA h g\u22121 at 10 mA g\u22121 with an average discharge potential of 2.4 V, while 66% of that capacity was retained after 200 cycles. At 500 mA g\u22121, the capacity dropped to 73 mA h g\u22121.", "question": "What's the electrolyte?", "answer": "carbonate-based", "answer_start": 192}
{"document_id": 75609, "context": "After testing the nanomesh electrodes, we compared our results to the performance of various 3D-nanostructured core\u2013shell cathodes reported in the literature (Fig. 6). To do that, we first constructed a Ragone plot to compare volumetric capacity and rate performance of the electrodes (Fig. 6a). Note that in this comparison, the capacities and currents are related to the total 3D volume of the cathodes, that is, including the volume of the 3D current collector, active material and the remaining porosity, but excluding any planar substrate.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75610, "context": "Finally, the versatility in designing nickel nanomesh with different pore sizes, porosities and surface areas can be used to further optimize the structure of nanomesh cathodes for either very high capacities or yet a higher rate performance. For example, in the electrodes prepared in this work, the 3D current collector occupied 24% of the electrode volume. Although this is in the normal range for 3D cathodes (that have up to 40% volume lost to the current collector, Table S3\u2020), it leaves room for improvement. Using nanomesh with yet a higher porosity (currently, up to 89%) may allow packing more active material into the structure and further increasing its volumetric capacity. If the nanomesh is designed with a proper combination of the nanowire diameter and spacing, the high surface area of the current collector can be preserved even for such highly porous nanomesh, maintaining its benefits in high utilization of active Li-ion materials. Because of its customizable structure, nanomesh can also be used to study the fundamental effects of a 3D structure on the properties of Li-ion electrodes. Knowing that nanomesh can also be fabricated as free-standing and flexible foil, the current work paves the way for future free-standing and stackable nanomesh-based cathodes. This, combined with the upscalable and generally feasible method of their fabrication, can make the cathodes attractive for practical application in high capacity and fast charging Li-ion batteries.", "question": "What's the cathode?", "answer": "nanomesh ", "answer_start": 159}
{"document_id": 75610, "context": "Finally, the versatility in designing nickel nanomesh with different pore sizes, porosities and surface areas can be used to further optimize the structure of nanomesh cathodes for either very high capacities or yet a higher rate performance. For example, in the electrodes prepared in this work, the 3D current collector occupied 24% of the electrode volume. Although this is in the normal range for 3D cathodes (that have up to 40% volume lost to the current collector, Table S3\u2020), it leaves room for improvement. Using nanomesh with yet a higher porosity (currently, up to 89%) may allow packing more active material into the structure and further increasing its volumetric capacity. If the nanomesh is designed with a proper combination of the nanowire diameter and spacing, the high surface area of the current collector can be preserved even for such highly porous nanomesh, maintaining its benefits in high utilization of active Li-ion materials. Because of its customizable structure, nanomesh can also be used to study the fundamental effects of a 3D structure on the properties of Li-ion electrodes. Knowing that nanomesh can also be fabricated as free-standing and flexible foil, the current work paves the way for future free-standing and stackable nanomesh-based cathodes. This, combined with the upscalable and generally feasible method of their fabrication, can make the cathodes attractive for practical application in high capacity and fast charging Li-ion batteries.", "question": "What's the cathode?", "answer": " nanomesh-based", "answer_start": 1260}
{"document_id": 75611, "context": "Similarly, the cycled S-C(PAN) electrodes paired with bare and coated LMO cathodes were investigated by XPS to confirm the SEI layer components and whether there was dissolved manganese deposited on the anode surface. Fig. 7 shows the XPS spectra of the Mn 2p and O 1s peaks on the S-C(PAN) anodes cycled at 25 \u00b0C (bare LMO and LMO-30 min) and 55 \u00b0C (LMO-30 min) after 100 cycles using 0.4C-rate. Fig. 7a shows the deposition of manganese on the anode surface when a cell was cycled using a bare LMO cathode and it displays two peaks at 640.1 (Mn2+) and 641.3 eV (Mn3+) for Mn 2p3/2. The decomposition of organic compounds from the electrolyte devastates the original SEI layer and the formation of a new SEI layer on the negative electrode surface in the form of MnxOy occurs. In the case of the LMO-30 min cathode, as shown in Fig. 7b and c, the deposition of manganese on the cycled S-C(PAN) electrode was hardly observed. In addition to XPS, EDS analysis and elemental mapping were also performed. No manganese content was detected on the anode surface when the cell was cycled with the LMO-30 min cathode at 25 \u00b0C (Fig. S6\u2020) and LMO-30 min cathode at 55 \u00b0C (Fig. S7\u2020). However, the cycled S-C(PAN) anode paired with bare LMO shows Mn distribution in Fig. S8.\u2020 As mentioned above, the PVDF@LGLZNO fibrous film protects the cathode and reduces the direct contact of the LMO cathode and the electrolyte. The peak of Mn was absent in the PVDF@LGLZNO coated LMO cathodes. DFT calculation further suggests that the dissolved manganese ion can be adsorbed on the garnet surface, whereby the adsorption energy of Mn2+ on the surface of the garnet was calculated as \u221253.067 kJ mol\u22121. Details about the estimation can be referred to in the ESI and Fig. S9.\u2020", "question": "What's the anode?", "answer": "S-C(PAN)", "answer_start": 282}
{"document_id": 75611, "context": "Similarly, the cycled S-C(PAN) electrodes paired with bare and coated LMO cathodes were investigated by XPS to confirm the SEI layer components and whether there was dissolved manganese deposited on the anode surface. Fig. 7 shows the XPS spectra of the Mn 2p and O 1s peaks on the S-C(PAN) anodes cycled at 25 \u00b0C (bare LMO and LMO-30 min) and 55 \u00b0C (LMO-30 min) after 100 cycles using 0.4C-rate. Fig. 7a shows the deposition of manganese on the anode surface when a cell was cycled using a bare LMO cathode and it displays two peaks at 640.1 (Mn2+) and 641.3 eV (Mn3+) for Mn 2p3/2. The decomposition of organic compounds from the electrolyte devastates the original SEI layer and the formation of a new SEI layer on the negative electrode surface in the form of MnxOy occurs. In the case of the LMO-30 min cathode, as shown in Fig. 7b and c, the deposition of manganese on the cycled S-C(PAN) electrode was hardly observed. In addition to XPS, EDS analysis and elemental mapping were also performed. No manganese content was detected on the anode surface when the cell was cycled with the LMO-30 min cathode at 25 \u00b0C (Fig. S6\u2020) and LMO-30 min cathode at 55 \u00b0C (Fig. S7\u2020). However, the cycled S-C(PAN) anode paired with bare LMO shows Mn distribution in Fig. S8.\u2020 As mentioned above, the PVDF@LGLZNO fibrous film protects the cathode and reduces the direct contact of the LMO cathode and the electrolyte. The peak of Mn was absent in the PVDF@LGLZNO coated LMO cathodes. DFT calculation further suggests that the dissolved manganese ion can be adsorbed on the garnet surface, whereby the adsorption energy of Mn2+ on the surface of the garnet was calculated as \u221253.067 kJ mol\u22121. Details about the estimation can be referred to in the ESI and Fig. S9.\u2020", "question": "What's the anode?", "answer": "S-C(PAN)", "answer_start": 1194}
{"document_id": 75612, "context": "Liquid rechargeable Zn\u2013air batteries were assembled with a homemade cell. A zinc sheet (purity 99.9 wt%) was used as the anode, which was polished with sandpaper before use. A mixed solution of 6 M KOH and 0.2 M Zn(Ac)2 was used as the electrolyte. The air cathode was composed of three layers, a catalyst layer, a nickel foam layer and a gas diffusion layer. The catalytic layer was fabricated by homogeneously mixing the NCAG/Fe\u2013Co catalyst, acetylene black, PTFE (60 wt%) at the mass ratio of 6:1:3. The nickel foam was treated with 0.2 M HCl, water and ethanol for 20 min, successively, and then vacuum dried at 60 \u00b0C before use. The three layers were compressed with a roll press to obtain the cathode, which was then vacuum dried at 60 \u00b0C for 3 h.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75612, "context": "Liquid rechargeable Zn\u2013air batteries were assembled with a homemade cell. A zinc sheet (purity 99.9 wt%) was used as the anode, which was polished with sandpaper before use. A mixed solution of 6 M KOH and 0.2 M Zn(Ac)2 was used as the electrolyte. The air cathode was composed of three layers, a catalyst layer, a nickel foam layer and a gas diffusion layer. The catalytic layer was fabricated by homogeneously mixing the NCAG/Fe\u2013Co catalyst, acetylene black, PTFE (60 wt%) at the mass ratio of 6:1:3. The nickel foam was treated with 0.2 M HCl, water and ethanol for 20 min, successively, and then vacuum dried at 60 \u00b0C before use. The three layers were compressed with a roll press to obtain the cathode, which was then vacuum dried at 60 \u00b0C for 3 h.", "question": "What's the anode?", "answer": "zinc sheet", "answer_start": 76}
{"document_id": 75612, "context": "Liquid rechargeable Zn\u2013air batteries were assembled with a homemade cell. A zinc sheet (purity 99.9 wt%) was used as the anode, which was polished with sandpaper before use. A mixed solution of 6 M KOH and 0.2 M Zn(Ac)2 was used as the electrolyte. The air cathode was composed of three layers, a catalyst layer, a nickel foam layer and a gas diffusion layer. The catalytic layer was fabricated by homogeneously mixing the NCAG/Fe\u2013Co catalyst, acetylene black, PTFE (60 wt%) at the mass ratio of 6:1:3. The nickel foam was treated with 0.2 M HCl, water and ethanol for 20 min, successively, and then vacuum dried at 60 \u00b0C before use. The three layers were compressed with a roll press to obtain the cathode, which was then vacuum dried at 60 \u00b0C for 3 h.", "question": "What's the electrolyte?", "answer": "A mixed solution of 6 M KOH and 0.2 M Zn(Ac)2", "answer_start": 174}
{"document_id": 75613, "context": "The non-aqueous gel polymer electrolyte (GPE) with dual redox additives was prepared by the \u201csolution-cast\u201d technique. Solid pellets of the host polymer PVdF-HFP (1 g) were put in 20 ml acetone and allowed to dissolve properly at room temperature by continuous stirring on a magnetic stirrer for 12 hours. Thereafter, 4 g IL was added in the polymer solution and stirred for another 12 hours. Redox additives (0.04 g KI) and (0.04 g DPA) were added in the PVdF-HFP/IL solution and stirred for further 12 hours at room temperature to obtain a homogeneous and clear solution. The solution was then poured in a glass petri dish and the common solvent acetone was allowed to evaporate slowly at room temperature. Upon complete evaporation of acetone, a free-standing, flexible and mechanically stable GPE film was obtained. The thickness of the dual redox-active GPE film was \u223c400 \u03bcm. For the comparison, GPEs of compositions PVdF-HFP:IL (20:80 w/w), and PVdF-HFP/IL/DPA and PVdF-HFP/IL/KI with different amounts of redox additives were also prepared by the same procedure, as described above. These GPEs were stored in a dry atmosphere to avoid moisture adsorption. These GPE films were characterized by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and thermogravimetric analysis (TGA). The room temperature ionic conductivity of all the GPEs was measured by EIS in the frequency range from 105 Hz to 1 Hz. The electrochemical stability window (ESW) for each GPE film was measured by LSV at a scan rate of 5 mV s\u22121. EIS and LSV were performed on an electrochemical analyzer (CHI660E, CH Instruments, USA). TGA was performed on a Perkin Elmer (USA) TGA-7 system from room temperature to 600 \u00b0C at a heating rate of 10 \u00b0C min\u22121 in a N2 atmosphere.", "question": "What's the electrolyte?", "answer": "non-aqueous gel polymer", "answer_start": 4}
{"document_id": 75613, "context": "The non-aqueous gel polymer electrolyte (GPE) with dual redox additives was prepared by the \u201csolution-cast\u201d technique. Solid pellets of the host polymer PVdF-HFP (1 g) were put in 20 ml acetone and allowed to dissolve properly at room temperature by continuous stirring on a magnetic stirrer for 12 hours. Thereafter, 4 g IL was added in the polymer solution and stirred for another 12 hours. Redox additives (0.04 g KI) and (0.04 g DPA) were added in the PVdF-HFP/IL solution and stirred for further 12 hours at room temperature to obtain a homogeneous and clear solution. The solution was then poured in a glass petri dish and the common solvent acetone was allowed to evaporate slowly at room temperature. Upon complete evaporation of acetone, a free-standing, flexible and mechanically stable GPE film was obtained. The thickness of the dual redox-active GPE film was \u223c400 \u03bcm. For the comparison, GPEs of compositions PVdF-HFP:IL (20:80 w/w), and PVdF-HFP/IL/DPA and PVdF-HFP/IL/KI with different amounts of redox additives were also prepared by the same procedure, as described above. These GPEs were stored in a dry atmosphere to avoid moisture adsorption. These GPE films were characterized by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and thermogravimetric analysis (TGA). The room temperature ionic conductivity of all the GPEs was measured by EIS in the frequency range from 105 Hz to 1 Hz. The electrochemical stability window (ESW) for each GPE film was measured by LSV at a scan rate of 5 mV s\u22121. EIS and LSV were performed on an electrochemical analyzer (CHI660E, CH Instruments, USA). TGA was performed on a Perkin Elmer (USA) TGA-7 system from room temperature to 600 \u00b0C at a heating rate of 10 \u00b0C min\u22121 in a N2 atmosphere.", "question": "What's the electrolyte?", "answer": "GPE", "answer_start": 41}
{"document_id": 75615, "context": "Carbon surfaces often exhibit poor electrochemical characteristics and therefore need special pretreatment, frequently termed as \u201cactivation\u201d. For surface sensitive redox couples the electron transfer at carbon electrodes may depend on edge plane exposure, surface functional groups and cleanliness. Porous electrode structures, such as carbon felts and carbon papers composed of randomly oriented CFs, also suffer from poor electrolyte accessibility, high pressure drops within the cell, and non-uniform electrolyte velocities. These issues limit the mass transport, for instance in redox flow cells, and thus their electrochemical performance. Some improvements have been achieved by modifying the cell architecture (by adding flow fields) and the electrode design. Another strategy is to employ electrodes that allow for control of the orientation of their fibres along the electrolyte flow.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75616, "context": "Owing to their attractive high carrier mobility, ambient stability, superior mechanical flexibility, large band gap and excellent optical properties, group IV\u2013V compounds, as a new kind of 2D materials, show a promising potential application for optoelectronic devices. Herein, 2D GeP nanosheets were exfoliated by a facile LPE method and a photoelectrochemical (PEC)-type photodetector employing a doctor blade deposited 2D GeP nanosheet electrode on an ITO-coated glass was fabricated. Ultrafast carrier dynamics was carefully probed by transient absorption spectroscopy, and the parameters of the photodetector, such as the voltage and electrolyte concentration, were highly optimized. It shows remarkable performance with a responsivity of 187.5 \u03bcA W\u22121, a detectivity of 2.14 \u00d7 1012 Jones and an EQE of 61.3% at an ultraviolet wavelength of 380 nm. The proposed strategy avoids complicated material preparation and device fabrication and facilitates large-area photodetection.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75617, "context": "In the context of reversibility, an excellent 1st cycle coulombic efficiency (CE) of \u223c91% could be obtained with the MWCNT containing electrode, which is much higher than a CE of \u223c78% recorded for the non-MWCNT containing counterpart (as reported in Section 3.3). Here, it may be mentioned that in another recently published study from our group (viz., ) addition of similarly functionalized MWCNTs to Na-titanate in the same way also enhanced the CE and cyclic stability in significant terms. In that study it was observed that the MWCNT network tends to uniformly \u2018wrap\u2019 the electrode-active particles due to favourable surface interaction, which, in turn, suppressed the occurrence of deleterious irreversible surface reactions with the electrolyte and, thus, improved the electrochemical performances. Even though looking more closely into such aspects here is beyond the scope of the presently reported work per se, it is not unlikely that the above mechanism may also be relevant to our Na-TM-oxide \u2013 MWCNT electrodes. On a slightly different note, a closer look at Fig. 3a, 7a and S9 (in the ESI\u2020) indicates that the overpotential (or polarization) associated with the initiation of electrochemical desodiation gets lowered in the presence of MWCNTs. This may, in turn, be a manifestation of the improved conductivity bestowed by the MWCNT network, which assumes greater importance here due to the presence of d0 TM-ions in the concerned Na-TM-oxide.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75619, "context": "FEC and DMC were purchased from SoulBrain Corp. LiPF6 was purchased from BASF Corp. Li chips (450 \u03bcm) were purchased from MTI Corp. The baseline electrolyte is 1 M LiPF6 + DMC/FEC (v/v = 8/2). The high fluorine content can provide a relatively robust electrolyte/electrode interface toward aggressive chemistries under high potentials. The electrolyte used for the protection failure study was commercial carbonate electrolyte: 1 M LiPF6 + EC/EMC (v/v = 4/6). TDAC\u00b7PF6 crystal powder was dissolved in baseline electrolyte to fabricate 0.2 M TDAC electrolyte. The NCA cathode, LMO cathode and graphite anode were composed of the active material, polyvinylidene fluoride (PVDF) binder and Super C carbon in a mass ratio of 90:5:5. The areal capacity of the NCA cathode, LMO cathode and graphite anode is 2.2 mA h cm\u22122. The NCA cathode and silicon\u2013graphene (Si\u2013C) anode sheets, with an areal capacity of \u223c3 mA h cm\u22122, were kindly provided by NanoGraf Corp. The formulation of the anode sheet was the Si\u2013C active material (mass ratio of 45:55), PVDF binder and Super C carbon in a mass ratio of 75:5:20. The loadings of the NCA cathode and Si\u2013C anode were \u223c18\u201319 mg cm\u22122 and \u223c3\u20134 mg cm\u22122, respectively. All electrode sheets were dried under vacuum at 80 \u00b0C overnight before use.", "question": "What's the cathode?", "answer": "LMO", "answer_start": 576}
{"document_id": 75619, "context": "FEC and DMC were purchased from SoulBrain Corp. LiPF6 was purchased from BASF Corp. Li chips (450 \u03bcm) were purchased from MTI Corp. The baseline electrolyte is 1 M LiPF6 + DMC/FEC (v/v = 8/2). The high fluorine content can provide a relatively robust electrolyte/electrode interface toward aggressive chemistries under high potentials. The electrolyte used for the protection failure study was commercial carbonate electrolyte: 1 M LiPF6 + EC/EMC (v/v = 4/6). TDAC\u00b7PF6 crystal powder was dissolved in baseline electrolyte to fabricate 0.2 M TDAC electrolyte. The NCA cathode, LMO cathode and graphite anode were composed of the active material, polyvinylidene fluoride (PVDF) binder and Super C carbon in a mass ratio of 90:5:5. The areal capacity of the NCA cathode, LMO cathode and graphite anode is 2.2 mA h cm\u22122. The NCA cathode and silicon\u2013graphene (Si\u2013C) anode sheets, with an areal capacity of \u223c3 mA h cm\u22122, were kindly provided by NanoGraf Corp. The formulation of the anode sheet was the Si\u2013C active material (mass ratio of 45:55), PVDF binder and Super C carbon in a mass ratio of 75:5:20. The loadings of the NCA cathode and Si\u2013C anode were \u223c18\u201319 mg cm\u22122 and \u223c3\u20134 mg cm\u22122, respectively. All electrode sheets were dried under vacuum at 80 \u00b0C overnight before use.", "question": "What's the anode?", "answer": "graphite", "answer_start": 592}
{"document_id": 75619, "context": "FEC and DMC were purchased from SoulBrain Corp. LiPF6 was purchased from BASF Corp. Li chips (450 \u03bcm) were purchased from MTI Corp. The baseline electrolyte is 1 M LiPF6 + DMC/FEC (v/v = 8/2). The high fluorine content can provide a relatively robust electrolyte/electrode interface toward aggressive chemistries under high potentials. The electrolyte used for the protection failure study was commercial carbonate electrolyte: 1 M LiPF6 + EC/EMC (v/v = 4/6). TDAC\u00b7PF6 crystal powder was dissolved in baseline electrolyte to fabricate 0.2 M TDAC electrolyte. The NCA cathode, LMO cathode and graphite anode were composed of the active material, polyvinylidene fluoride (PVDF) binder and Super C carbon in a mass ratio of 90:5:5. The areal capacity of the NCA cathode, LMO cathode and graphite anode is 2.2 mA h cm\u22122. The NCA cathode and silicon\u2013graphene (Si\u2013C) anode sheets, with an areal capacity of \u223c3 mA h cm\u22122, were kindly provided by NanoGraf Corp. The formulation of the anode sheet was the Si\u2013C active material (mass ratio of 45:55), PVDF binder and Super C carbon in a mass ratio of 75:5:20. The loadings of the NCA cathode and Si\u2013C anode were \u223c18\u201319 mg cm\u22122 and \u223c3\u20134 mg cm\u22122, respectively. All electrode sheets were dried under vacuum at 80 \u00b0C overnight before use.", "question": "What's the electrolyte?", "answer": "1 M LiPF6 + DMC/FEC", "answer_start": 160}
{"document_id": 75619, "context": "FEC and DMC were purchased from SoulBrain Corp. LiPF6 was purchased from BASF Corp. Li chips (450 \u03bcm) were purchased from MTI Corp. The baseline electrolyte is 1 M LiPF6 + DMC/FEC (v/v = 8/2). The high fluorine content can provide a relatively robust electrolyte/electrode interface toward aggressive chemistries under high potentials. The electrolyte used for the protection failure study was commercial carbonate electrolyte: 1 M LiPF6 + EC/EMC (v/v = 4/6). TDAC\u00b7PF6 crystal powder was dissolved in baseline electrolyte to fabricate 0.2 M TDAC electrolyte. The NCA cathode, LMO cathode and graphite anode were composed of the active material, polyvinylidene fluoride (PVDF) binder and Super C carbon in a mass ratio of 90:5:5. The areal capacity of the NCA cathode, LMO cathode and graphite anode is 2.2 mA h cm\u22122. The NCA cathode and silicon\u2013graphene (Si\u2013C) anode sheets, with an areal capacity of \u223c3 mA h cm\u22122, were kindly provided by NanoGraf Corp. The formulation of the anode sheet was the Si\u2013C active material (mass ratio of 45:55), PVDF binder and Super C carbon in a mass ratio of 75:5:20. The loadings of the NCA cathode and Si\u2013C anode were \u223c18\u201319 mg cm\u22122 and \u223c3\u20134 mg cm\u22122, respectively. All electrode sheets were dried under vacuum at 80 \u00b0C overnight before use.", "question": "What's the cathode?", "answer": "NCA", "answer_start": 821}
{"document_id": 75619, "context": "FEC and DMC were purchased from SoulBrain Corp. LiPF6 was purchased from BASF Corp. Li chips (450 \u03bcm) were purchased from MTI Corp. The baseline electrolyte is 1 M LiPF6 + DMC/FEC (v/v = 8/2). The high fluorine content can provide a relatively robust electrolyte/electrode interface toward aggressive chemistries under high potentials. The electrolyte used for the protection failure study was commercial carbonate electrolyte: 1 M LiPF6 + EC/EMC (v/v = 4/6). TDAC\u00b7PF6 crystal powder was dissolved in baseline electrolyte to fabricate 0.2 M TDAC electrolyte. The NCA cathode, LMO cathode and graphite anode were composed of the active material, polyvinylidene fluoride (PVDF) binder and Super C carbon in a mass ratio of 90:5:5. The areal capacity of the NCA cathode, LMO cathode and graphite anode is 2.2 mA h cm\u22122. The NCA cathode and silicon\u2013graphene (Si\u2013C) anode sheets, with an areal capacity of \u223c3 mA h cm\u22122, were kindly provided by NanoGraf Corp. The formulation of the anode sheet was the Si\u2013C active material (mass ratio of 45:55), PVDF binder and Super C carbon in a mass ratio of 75:5:20. The loadings of the NCA cathode and Si\u2013C anode were \u223c18\u201319 mg cm\u22122 and \u223c3\u20134 mg cm\u22122, respectively. All electrode sheets were dried under vacuum at 80 \u00b0C overnight before use.", "question": "What's the anode?", "answer": "silicon\u2013graphene (Si\u2013C)", "answer_start": 837}
{"document_id": 75619, "context": "FEC and DMC were purchased from SoulBrain Corp. LiPF6 was purchased from BASF Corp. Li chips (450 \u03bcm) were purchased from MTI Corp. The baseline electrolyte is 1 M LiPF6 + DMC/FEC (v/v = 8/2). The high fluorine content can provide a relatively robust electrolyte/electrode interface toward aggressive chemistries under high potentials. The electrolyte used for the protection failure study was commercial carbonate electrolyte: 1 M LiPF6 + EC/EMC (v/v = 4/6). TDAC\u00b7PF6 crystal powder was dissolved in baseline electrolyte to fabricate 0.2 M TDAC electrolyte. The NCA cathode, LMO cathode and graphite anode were composed of the active material, polyvinylidene fluoride (PVDF) binder and Super C carbon in a mass ratio of 90:5:5. The areal capacity of the NCA cathode, LMO cathode and graphite anode is 2.2 mA h cm\u22122. The NCA cathode and silicon\u2013graphene (Si\u2013C) anode sheets, with an areal capacity of \u223c3 mA h cm\u22122, were kindly provided by NanoGraf Corp. The formulation of the anode sheet was the Si\u2013C active material (mass ratio of 45:55), PVDF binder and Super C carbon in a mass ratio of 75:5:20. The loadings of the NCA cathode and Si\u2013C anode were \u223c18\u201319 mg cm\u22122 and \u223c3\u20134 mg cm\u22122, respectively. All electrode sheets were dried under vacuum at 80 \u00b0C overnight before use.", "question": "What's the electrolyte?", "answer": "0.2 M TDAC", "answer_start": 535}
{"document_id": 75623, "context": "In summary, we demonstrated the use of a multicomponent electrolyte containing sodium perchlorate, urea, N,N-dimethylformamide (DMF) and water, enabling us to immensely decrease the amount of water, forming a complex solvent sheath and a uniform SEI layer composed of complexes with inorganic salt Na2CO3 and other organic components between the interface of the NTP anode and electrolyte. Such an electrolyte provides a voltage window up to 2.8 V and ensures the feasibility of stable and reversible operation of a NVP/NTP sodium ion battery. This battery exhibits an excellent flat voltage platform of about 1.2 V and achieves 86% capacity retention after 100 cycles at the 10C rate. Simultaneously, a NiHCF//NTP full cell with the MCAE displays 80% capacity retention after 2000 cycles at 2C rate. In addition, this MCAE displays high safety, a wide operating temperature range (\u221250 \u00b0C to 50 \u00b0C) and high ionic conductivity because of the roles of urea and DMF additives. And above all, the fluorine-free MCAE makes the battery much safer and more environmentally friendly than the existing battery systems with highly concentrated aqueous electrolytes. Meanwhile, we provide a new perspective that can be expanded to other systems of aqueous sodium-ion full cells, which promotes the application of safe, environmentally friendly and stable AISBs for large-scale energy storage.", "question": "What's the anode?", "answer": "NTP ", "answer_start": 363}
{"document_id": 75623, "context": "In summary, we demonstrated the use of a multicomponent electrolyte containing sodium perchlorate, urea, N,N-dimethylformamide (DMF) and water, enabling us to immensely decrease the amount of water, forming a complex solvent sheath and a uniform SEI layer composed of complexes with inorganic salt Na2CO3 and other organic components between the interface of the NTP anode and electrolyte. Such an electrolyte provides a voltage window up to 2.8 V and ensures the feasibility of stable and reversible operation of a NVP/NTP sodium ion battery. This battery exhibits an excellent flat voltage platform of about 1.2 V and achieves 86% capacity retention after 100 cycles at the 10C rate. Simultaneously, a NiHCF//NTP full cell with the MCAE displays 80% capacity retention after 2000 cycles at 2C rate. In addition, this MCAE displays high safety, a wide operating temperature range (\u221250 \u00b0C to 50 \u00b0C) and high ionic conductivity because of the roles of urea and DMF additives. And above all, the fluorine-free MCAE makes the battery much safer and more environmentally friendly than the existing battery systems with highly concentrated aqueous electrolytes. Meanwhile, we provide a new perspective that can be expanded to other systems of aqueous sodium-ion full cells, which promotes the application of safe, environmentally friendly and stable AISBs for large-scale energy storage.", "question": "What's the electrolyte?", "answer": "sodium perchlorate, urea, N,N-dimethylformamide (DMF) and wate", "answer_start": 79}
{"document_id": 75625, "context": "The electrochemical properties of the prepared \u03b1-MnS@NS-C samples were evaluated with lithium metal as the reference electrode. For electrochemical measurements, the obtained \u03b1-MnS@NS-C material was mixed with carbon black (SuperP) and polyacrylic acid binder in the stoichiometric ratio of 80:10:10. This slurry was coated on Cu foil and vacuum dried at 120 \u00b0C for 12 h to form the anode. An active material loading of 1.5 mg cm\u22122 was used. A 2032-coin type cell comprising a cathode and lithium metal anode separated by a polymer membrane (Celgard 2400) and a glass fiber (Whatman GF/B) was fabricated in an Ar-filled glove box and aged for 12 h before electrochemical measurements. The electrolyte employed was a 1:1 mixture of ethylene carbonate and dimethyl carbonate containing 1 M LiPF6. Galvanostatic measurements were performed on test coin cells using a programmable battery tester (BTS-2004H, Nagano, Japan) over the potential range of 0.01\u20133.0 V versus Li+/Li. Cyclic voltammetry (CV) measurements were performed using a Biologic instrument within the voltage range of 0.01\u20133.0 V and a scan rate of 0.1\u20131.0 mV s\u22121.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75625, "context": "The electrochemical properties of the prepared \u03b1-MnS@NS-C samples were evaluated with lithium metal as the reference electrode. For electrochemical measurements, the obtained \u03b1-MnS@NS-C material was mixed with carbon black (SuperP) and polyacrylic acid binder in the stoichiometric ratio of 80:10:10. This slurry was coated on Cu foil and vacuum dried at 120 \u00b0C for 12 h to form the anode. An active material loading of 1.5 mg cm\u22122 was used. A 2032-coin type cell comprising a cathode and lithium metal anode separated by a polymer membrane (Celgard 2400) and a glass fiber (Whatman GF/B) was fabricated in an Ar-filled glove box and aged for 12 h before electrochemical measurements. The electrolyte employed was a 1:1 mixture of ethylene carbonate and dimethyl carbonate containing 1 M LiPF6. Galvanostatic measurements were performed on test coin cells using a programmable battery tester (BTS-2004H, Nagano, Japan) over the potential range of 0.01\u20133.0 V versus Li+/Li. Cyclic voltammetry (CV) measurements were performed using a Biologic instrument within the voltage range of 0.01\u20133.0 V and a scan rate of 0.1\u20131.0 mV s\u22121.", "question": "What's the anode?", "answer": "lithium metal", "answer_start": 489}
{"document_id": 75625, "context": "The electrochemical properties of the prepared \u03b1-MnS@NS-C samples were evaluated with lithium metal as the reference electrode. For electrochemical measurements, the obtained \u03b1-MnS@NS-C material was mixed with carbon black (SuperP) and polyacrylic acid binder in the stoichiometric ratio of 80:10:10. This slurry was coated on Cu foil and vacuum dried at 120 \u00b0C for 12 h to form the anode. An active material loading of 1.5 mg cm\u22122 was used. A 2032-coin type cell comprising a cathode and lithium metal anode separated by a polymer membrane (Celgard 2400) and a glass fiber (Whatman GF/B) was fabricated in an Ar-filled glove box and aged for 12 h before electrochemical measurements. The electrolyte employed was a 1:1 mixture of ethylene carbonate and dimethyl carbonate containing 1 M LiPF6. Galvanostatic measurements were performed on test coin cells using a programmable battery tester (BTS-2004H, Nagano, Japan) over the potential range of 0.01\u20133.0 V versus Li+/Li. Cyclic voltammetry (CV) measurements were performed using a Biologic instrument within the voltage range of 0.01\u20133.0 V and a scan rate of 0.1\u20131.0 mV s\u22121.", "question": "What's the electrolyte?", "answer": "1:1 mixture of ethylene carbonate and dimethyl carbonate containing 1 M LiPF6", "answer_start": 716}
{"document_id": 75626, "context": "Fig. 1a schematically shows the composition of the light-assisted Li\u2013CO2 battery, which consisted of a Li anode, a non-aqueous electrolyte, a separator, and a cathode with the photo-electro-catalyst. Upon discharging under illumination (Fig. 1b), the photocatalyst is excited to generate holes and electrons after absorbing photons. Since the conduction band potential (VCB) of the photocatalyst is more negative than the standard redox potential of 2.8 V, photoexcited electrons could reduce CO2 by a photocatalytic reaction. Notably, the solar light provides significant energy for CO2 reduction in sharp contrast with the conventional Li\u2013CO2 battery, in which the carbon dioxide reduction reaction (CO2RR) process is driven by the electrocatalytic reaction. Meanwhile, photoexcited holes capture the electrons from the Li anode through the external circuit due to the more positive valence band potential (VVB) than 2.8 V, ensuring the continuous supply of photoexcited electrons for the CO2RR process. During the charging process (Fig. 1c), the inverse reaction 4Li + 3CO2 \u2192 2Li2CO3 + C is promoted by the photoexcited holes on the cathode on account of the positive VB position compared with 2.8 V. Simultaneously, the photoexcited electrons transfer to the anode through the external circuit to reduce Li+ to Li metal. In this photoassisted charging process, the photovoltage generated on the photo-catalyst is utilized to compensate the charging potential of the Li\u2013CO2 battery.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75626, "context": "Fig. 1a schematically shows the composition of the light-assisted Li\u2013CO2 battery, which consisted of a Li anode, a non-aqueous electrolyte, a separator, and a cathode with the photo-electro-catalyst. Upon discharging under illumination (Fig. 1b), the photocatalyst is excited to generate holes and electrons after absorbing photons. Since the conduction band potential (VCB) of the photocatalyst is more negative than the standard redox potential of 2.8 V, photoexcited electrons could reduce CO2 by a photocatalytic reaction. Notably, the solar light provides significant energy for CO2 reduction in sharp contrast with the conventional Li\u2013CO2 battery, in which the carbon dioxide reduction reaction (CO2RR) process is driven by the electrocatalytic reaction. Meanwhile, photoexcited holes capture the electrons from the Li anode through the external circuit due to the more positive valence band potential (VVB) than 2.8 V, ensuring the continuous supply of photoexcited electrons for the CO2RR process. During the charging process (Fig. 1c), the inverse reaction 4Li + 3CO2 \u2192 2Li2CO3 + C is promoted by the photoexcited holes on the cathode on account of the positive VB position compared with 2.8 V. Simultaneously, the photoexcited electrons transfer to the anode through the external circuit to reduce Li+ to Li metal. In this photoassisted charging process, the photovoltage generated on the photo-catalyst is utilized to compensate the charging potential of the Li\u2013CO2 battery.", "question": "What's the anode?", "answer": "Li ", "answer_start": 103}
{"document_id": 75626, "context": "Fig. 1a schematically shows the composition of the light-assisted Li\u2013CO2 battery, which consisted of a Li anode, a non-aqueous electrolyte, a separator, and a cathode with the photo-electro-catalyst. Upon discharging under illumination (Fig. 1b), the photocatalyst is excited to generate holes and electrons after absorbing photons. Since the conduction band potential (VCB) of the photocatalyst is more negative than the standard redox potential of 2.8 V, photoexcited electrons could reduce CO2 by a photocatalytic reaction. Notably, the solar light provides significant energy for CO2 reduction in sharp contrast with the conventional Li\u2013CO2 battery, in which the carbon dioxide reduction reaction (CO2RR) process is driven by the electrocatalytic reaction. Meanwhile, photoexcited holes capture the electrons from the Li anode through the external circuit due to the more positive valence band potential (VVB) than 2.8 V, ensuring the continuous supply of photoexcited electrons for the CO2RR process. During the charging process (Fig. 1c), the inverse reaction 4Li + 3CO2 \u2192 2Li2CO3 + C is promoted by the photoexcited holes on the cathode on account of the positive VB position compared with 2.8 V. Simultaneously, the photoexcited electrons transfer to the anode through the external circuit to reduce Li+ to Li metal. In this photoassisted charging process, the photovoltage generated on the photo-catalyst is utilized to compensate the charging potential of the Li\u2013CO2 battery.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75626, "context": "Fig. 1a schematically shows the composition of the light-assisted Li\u2013CO2 battery, which consisted of a Li anode, a non-aqueous electrolyte, a separator, and a cathode with the photo-electro-catalyst. Upon discharging under illumination (Fig. 1b), the photocatalyst is excited to generate holes and electrons after absorbing photons. Since the conduction band potential (VCB) of the photocatalyst is more negative than the standard redox potential of 2.8 V, photoexcited electrons could reduce CO2 by a photocatalytic reaction. Notably, the solar light provides significant energy for CO2 reduction in sharp contrast with the conventional Li\u2013CO2 battery, in which the carbon dioxide reduction reaction (CO2RR) process is driven by the electrocatalytic reaction. Meanwhile, photoexcited holes capture the electrons from the Li anode through the external circuit due to the more positive valence band potential (VVB) than 2.8 V, ensuring the continuous supply of photoexcited electrons for the CO2RR process. During the charging process (Fig. 1c), the inverse reaction 4Li + 3CO2 \u2192 2Li2CO3 + C is promoted by the photoexcited holes on the cathode on account of the positive VB position compared with 2.8 V. Simultaneously, the photoexcited electrons transfer to the anode through the external circuit to reduce Li+ to Li metal. In this photoassisted charging process, the photovoltage generated on the photo-catalyst is utilized to compensate the charging potential of the Li\u2013CO2 battery.", "question": "What's the anode?", "answer": "Li", "answer_start": 822}
{"document_id": 75627, "context": "The energy and power of all the cells are also compared in the form of Ragone plots (i.e., the plots of specific energy against effective power density), as shown in Fig. 7f. All the capacitor cells show a standard variation of Ragone plots, which are generally observed for the power sources like supercapacitors. The effect of incorporating redox additives (DPA/KI, individually or dual) in the electrolyte component can be directly observed on the energy and power of the capacitor cells. It may be noticed that the enhancement in specific energy due to the incorporation of redox additives has been observed for each value of power density (Fig. 7f). The optimum value of Esp is found to be \u223c73 W h kg\u22121 at a Peff of \u223c568 W kg\u22121 for Cell#4 (with the redox-active GPE containing dual redox additives). The high specific energy of this carbon supercapacitor is not only due to high specific capacitance owing to dual redox activity at the interfaces (according to Scheme (3), mentioned above), it is also due to relatively high operating voltage window (\u223c2.5 V) of electrochemically stable IL-incorporated, non-aqueous gel polymer films as electrolytes. The specific energy values of the present capacitor cell (Cell#4) are substantially higher than or equivalent to that of many reported carbon supercapacitors based on redox-active non-aqueous electrolytes including GPEs. A comparison of the present system with similar devices, reported in the literature, is given in Table 3.", "question": "What's the electrolyte?", "answer": "non-aqueous gel polymer films", "answer_start": 1109}
{"document_id": 75628, "context": "To test the cyclability of columnar lithium metal during cell operation, operando GISAXS was used to probe the morphology of lithium metal deposits during cycling. GISAXS, being sensitive to length scales on the order of a few to a few hundred nanometers, exhibits a distinct set of evenly spaced intensity oscillations in the qy direction (Fig. 12) arising from the highly monodispersed columnar microstructure, with column diameters of \u223c100\u2013200 nm depending on current density (Fig. S8\u2020); the periodicity \u0394qy of these oscillations is related to the column diameter d by \u0394qy = 2\u03c0/d. Oscillations in the qz direction arise from interference between X-rays scattered from the lithium\u2013electrolyte and lithium\u2013copper interfaces, complicated by multiple scattering and indicate the top surface of the film is very smooth. At the end of plating 1 mA h cm\u22122 of lithium, strong intensity oscillations are apparent in the qy direction, indicative of a columnar morphology (Fig. 12c). After stripping half of the plated capacity (0.5 mA h cm\u22122), the intensity oscillations are still present, though broader and less pronounced, indicating the columnar morphology is maintained but is less monodisperse in size and shape (Fig. 12d). At the end of the second plating half cycle the oscillations are even less pronounced (Fig. 12e), suggesting that cycling a large percentage of the plated 1 mA h cm\u22122 capacity, in this case 50%, with a columnar morphology leads to a loss of uniformity in the microstructure. This is further evidenced by the fact that if all the columnar lithium is stripped to a 1 V vs. Li/Li+ cutoff voltage, the second plating half cycle does not produce a columnar morphology (Fig. S9\u2020). This is consistent with the report from Zhang et al. which demonstrated using ex situ SEM that lithium is stripped from both the tops and sides of lithium nanorods, enabled by the high lithium-ion diffusivity of the SEI, disrupting uniform re-plating onto the high aspect ratio columns. This limits the cycle life of practical batteries which must uniformly plate and strip high capacities of lithium during each charge/discharge cycle, particularly in \u201canode-free\u201d configurations. Thus, further understanding the impact of additional conditions, including electrochemical profile and mechanical compression (stack pressure), which could help promote the growth of columns with a lower aspect ratio (disc-like rather than rod-like), will be crucial to maintaining morphology control after hundreds of cycles and enhancing the long term cyclability of lithium metal batteries. The effects of compression, the presence of a separator, and lower volume of electrolyte, in particular, require additional investigation as the behavior observed using the flooded open cell design employed in this study may not be directly transferable to a commercial-type battery.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75629, "context": "To investigate the electrochemical reaction mechanism of Zn2+ in the NV NSs@ACC//Zn battery, ex situ XRD and XPS analyses are carried out. Fig. 5a shows the different charge/discharge states during the 2nd cycle at 0.1 A g\u22121. During the discharge process, it can be observed that a small amount of (NH4)2V10O25\u00b78H2O transforms to the new phase of Zn3(OH)2V2O7\u00b72H2O (JCPDS no. 50-0570) (Fig. 5b), which could be attributed to H+/Zn2+-co-insertion into the VO layers. The peaks between the range of 10\u201335\u00b0 for the samples cha.0.8 V and cha.1.4 V were more obvious than that for the discharge process. This is attributed to the XRD pattern of Zn(OH)2 impurity, which could arise from the deposited Zn(OH)2@glass fiber adhered on the surface of the sample. In addition, as can be seen in Fig. 5c, the peak for the (001) plane evidently shifts to a lower degree from 8.3 to 6.7\u00b0 after immersion in the electrolyte for 1 h, corresponding to an increase in the interlayer spacing from 10.6 \u00c5 to 13.2 \u00c5. Note that the interlayer distance during the subsequent discharge/charge process is always larger than that of the pristine sample, revealing that the expansion of the layer spacing upon immersion arose from water molecule intercalation, which can weaken the electrostatic attraction and thus facilitate the migration of multivalent Zn2+. More significantly, the diffraction peak (001) of NV NSs@ACC shifts to a lower degree during the discharge process and almost moves back to its original position during the charge process. The d-spacing of the (001) plane in different samples corresponding to the ex situ XRD patterns are presented in Table S4.\u2020 These results indicate the highly reversible Zn2+ intercalation/deintercalation of the NV host without the destruction of its open-framework during the subsequent discharge/charge process.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75630, "context": "The small thickness of an active material and its high contact area with the current collector and electrolyte can be simultaneously realized using 3D-structured conductive substrates. The higher surface area of a 3D-current collector can allow distributing the active material over a thinner coating (or, similarly, increasing the loading of the active material while keeping its thickness low), simultaneously maintaining open porosity for the electrolyte. Such core\u2013shell, structurally integral electrode design can be achieved with a variety of micro- and nanostructured 3D substrates, such as micropillars, nanoporous metals, inverse metal opals or interconnected metal nanowires, which have a big advantage over macroscopic 3D foams in effective utilization of the electrode volume. Compared to nanostructured electrodes based on nanoparticles embedded in binding and conductive additives, the electrodes based on monolithic 3D structures are typically less tortious (translating to lower polarization resistance) and can be often fabricated with high spatial precision (e.g. by lithography or area-selective electrodeposition), making them particularly attractive for all-solid-state microbatteries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75633, "context": "Fig. 2a shows the photographs of the PLB-CSE; the as-prepared membrane is free-standing and exhibits excellent ductility and flexibility. It is worth noting that the composite electrolyte membrane with such a high proportion of inorganic ceramic particles still exhibits great flexibility, and no cracks could be found in the electrolyte films upon bending, indicating an excellent mechanical capability. This flexible and strong PLB-CSE membrane can be used in flexible devices. To further analyze the microstructure morphologies and the distribution of LATP inorganic nanoparticles, the SEM image is presented in Fig. 2b. The SEM image shows a flat and homogeneous surface free of pores for the electrolyte membrane; the LATP ceramic fillers are uniformly dispersed in the polymer matrix. Fig. 2c displays the cross-sectional features of the PLB-CSE membrane, the thickness of which is about 60 \u03bcm, and the corresponding EDS mapping images of titanium (Ti), phosphorus (P), sulfur (S), and fluorine (F) are given in Fig. 2d\u2013g. It can be observed that the LATP ceramic particles are uniformly dispersed in the electrolyte membrane, and the homogeneous LATP inorganic particles are in close contact with each other forming a continuous network structure, allowing Li-ion transfer between LATP ceramic grains, enabling a fast and efficient conductive pathway, which can promote ion transportation within the composite electrolyte.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75634, "context": "Zero-valent nonmetal engineering can also be extended to P-regulated metal nitrides and carbides. Fu et al. selected small-sized tungsten nitride (WN; \u223c3 nm) as the model to investigate the function of P dopants. The experimental results confirmed that P modification could lead to significant enhancements in catalytic activity and stability for HER in acidic media, particularly with low onset overpotential of 46 mV, Tafel slope of 54 mV dec\u22121, large exchange current density of 0.35 mA cm\u22122, and long-term stability. The enhanced performance could be attributed to the interaction of P with WN, which can increase the work function. Different from the earlier reported uncontrolled P-doping strategy, Tang et al. fabricated hierarchical nanowires comprising P-doped MoC2 nanoparticles via the controlled carbonization of ternary organic\u2013inorganic (MoOx\u2013phytic acid\u2013polyaniline) nanohybrids. A series of samples with different contents of P in the range of 0\u20133.4 wt% were successfully prepared by varying the introduced amount of polyaniline. With an increase in the P content, the XPS peaks for Mo 3d shifted to lower binding energies, signifying that the electron density of Mo2+ in MoC2 was enriched by doping P. In addition, P doping could enrich the electrons around the Fermi level in MoC2, resulting in weakened Mo\u2013H and promoted Hads desorption in HER kinetics. Combining optimal Hads desorption energy on Mo2C and hierarchical structure, the P\u2013Mo2C@C nanowires with controlled P doping delivered benchmark HER activity and good stability in acidic electrolytes.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75636, "context": "Among the many proposed applications of graphene-based materials, supercapacitors, also known as electrochemical capacitors, have been an active area of research for the past decade. Compared with secondary batteries, graphene-based supercapacitors are electrochemical energy storage devices that promise outstanding power density, charge/discharge rate, cycling stability, and operational safety. Supercapacitors are often utilized individually or in tandem with batteries for energy storage and supply (Scheme 1a(i)). They can be classified into two types: the electric double-layer capacitor (EDLC) (Scheme 1a(ii)) and the pseudocapacitor (Scheme 1a(iii)). The energy storage mechanism of the EDLC involves a simple charge separation at the interface between the conductive electrode and the electrolyte. Because there is no chemical transformation at the EDLC electrodes, the system is quite stable, although the specific capacitance is relatively low. In comparison, charge storage in a pseudocapacitor is predominantly achieved via the redox or faradic transformation of capacitive electrode materials, such as metal oxides and conductive polymers. The specific capacitance of the pseudocapacitor is generally high, but gradually decays because of structural collapse and degradation. A composite of a conductive substance and a pseudocapacitive material is desirable to enhance the overall capacitance, charge/discharge rate, and cycling lifetime. Graphene is a promising conductive component because it has a large surface area, and excellent electronic and mechanical properties. To develop a high-performance pseudocapacitor, we focused on developing a conductive polymer as an electrode counterpart to graphene. Various graphene\u2013polymer composites with non-covalent and covalent interactions have been synthesized, and high capacitive performances have been achieved. The non-covalent interaction between graphene and polymers limits charge transfer at their interface, and hence constrains the cycling stability (Scheme 1b(i)). To address this issue, we propose the formation of the covalent bond between graphene and redox-active polymers.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75640, "context": "In conclusion, a new synthesis approach is presented wherein doped La2Zr2O7 pyrochlore nanocrystals are synthesized with a composition that will result in the correct stoichiometry to form Li-conducting garnets based on Li7La3Zr2O12. La and Ta co-doped pyrochlores with a La:Zr:Ta stoichiometry of 3:1.4:0.6 are demonstrated to readily form garnet-type Li6.4La3Zr1.4Ta0.6O12 between 400\u2013550 \u00b0C in a ternary mixture of molten LiNO3\u2013LiOH\u2013Li2O2, with unprecedentedly low reaction temperatures. Pyrochlores can also be used as quasi-single-source precursors and blended with a Li source and reactively sintered in 2 hours at 1200 \u00b0C to form highly dense, highly conducting garnet ceramics with a microstructure similar to that obtained through advanced sintering techniques, providing a unique and successful approach to dense garnet electrolytes that can be easily extended to more advanced ceramic forming techniques such as tape-casting or additive manufacturing, potentially improving processability of garnet solid-electrolytes for solid-state lithium batteries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75641, "context": "The chemical composition and structure of the SEI after 1.0 mA h cm\u22122 deposition at 0.2 mA cm\u22122, 0.5 mA cm\u22122 and 1.0 mA cm\u22122 were further probed by XPS depth profiling. The XPS depth profiles of the N 1s, Li 1s, F 1s, C 1s, and O 1s spectra are shown in Fig. 6a\u2013i and S13\u2013S15.\u2020 At 0.2 mA cm\u22122 (Fig. 6a\u2013c), the major inorganic components comprising Li3N and LiF were distributed homogeneously in the depth direction of the SEI. Li3N, as the reduction product of LiNO3, is a well-known Li ion conductor with a conductivity of 10\u22123 S cm\u22121 at room temperature; LiF, either as an electrolyte additive or SEI component, can improve the diffusion of lithium ions at the electrode surface. The mixed Li3N and LiF layer can facilitate rapid lithium ion diffusion, stabilize the SEI and provide uniform electrodeposition. For the high current densities, especially 1.0 mA cm\u22122 (Fig. 6g\u2013i), the SEI lacked the inorganic components Li3N and LiF; instead, organic ROLi species were observed. The poor ionic conductivity of ROLi impeded sufficient transport of Li ions towards the electrode surface at high current densities and induced preferential deposition. The very different SEI composition resulting from the repeated SEI breakdown and repair processes also reinforced the rupturing and re-forming cycles of the SEI. In addition, the XPS chemical composition results are in accordance with the mechanical properties obtained by AFM force probing. The SEI formed at a low current density contained a higher content of inorganic components and greater mechanical strength, while the SEI formed at a high current density contained a mixed organic\u2013inorganic layer and was relatively soft (Fig. 6j\u2013l).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75643, "context": "Polyanionic materials are a series of compounds containing polyhedral anionic structural units, which are linked to construct a three-dimensional network structure by strong covalent bonds. The unique structure endows the compounds with a stable crystal structure, moderate capacity, high operating voltage, and safety. Among them, monoclinic LiV2(PO4)3 (discharges to be Li3V2(PO4)3) is one of the most attractive cathode materials for primary batteries, which has stable voltage plateaus between 3.0 V and 4.3 V (vs. Li+/Li) and a suitable theoretical specific capacity (133 mA h g\u22121) corresponding to the insertion of two Li ions per formula unit. Most importantly, the unique NASICON structure of Li3V2(PO4)3 facilitates Li+ conduction and delivers faster Li+ diffusion kinetics when compared with traditional cathode materials such as LiFePO4, LiCoO2, and LiNi1/3Co1/3Mn1/3O2, ensuring superior rate capability and low-temperature performance. Thus, LiV2(PO4)3 has great potential for application as a cathode material for lithium primary batteries. For practical application, the shelf life of the Li/LiV2(PO4)3 batteries should be long enough; this means that the self-discharge rate should be as low as possible. Since the Li/LiV2(PO4)3 primary battery possesses a high open-circuit voltage (OCV) of about 4.1 V, the side reactions among electrode materials, electrolyte, and even current collectors can severely affect the shelf life of these batteries. In addition, the corrosion of the current collector leads to self-discharge. Therefore, stabilizing the interface between the electrode and electrolyte is essential.", "question": "What's the cathode?", "answer": "monoclinic LiV2(PO4)3 (discharges to be Li3V2(PO4)3", "answer_start": 332}
{"document_id": 75643, "context": "Polyanionic materials are a series of compounds containing polyhedral anionic structural units, which are linked to construct a three-dimensional network structure by strong covalent bonds. The unique structure endows the compounds with a stable crystal structure, moderate capacity, high operating voltage, and safety. Among them, monoclinic LiV2(PO4)3 (discharges to be Li3V2(PO4)3) is one of the most attractive cathode materials for primary batteries, which has stable voltage plateaus between 3.0 V and 4.3 V (vs. Li+/Li) and a suitable theoretical specific capacity (133 mA h g\u22121) corresponding to the insertion of two Li ions per formula unit. Most importantly, the unique NASICON structure of Li3V2(PO4)3 facilitates Li+ conduction and delivers faster Li+ diffusion kinetics when compared with traditional cathode materials such as LiFePO4, LiCoO2, and LiNi1/3Co1/3Mn1/3O2, ensuring superior rate capability and low-temperature performance. Thus, LiV2(PO4)3 has great potential for application as a cathode material for lithium primary batteries. For practical application, the shelf life of the Li/LiV2(PO4)3 batteries should be long enough; this means that the self-discharge rate should be as low as possible. Since the Li/LiV2(PO4)3 primary battery possesses a high open-circuit voltage (OCV) of about 4.1 V, the side reactions among electrode materials, electrolyte, and even current collectors can severely affect the shelf life of these batteries. In addition, the corrosion of the current collector leads to self-discharge. Therefore, stabilizing the interface between the electrode and electrolyte is essential.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75643, "context": "Polyanionic materials are a series of compounds containing polyhedral anionic structural units, which are linked to construct a three-dimensional network structure by strong covalent bonds. The unique structure endows the compounds with a stable crystal structure, moderate capacity, high operating voltage, and safety. Among them, monoclinic LiV2(PO4)3 (discharges to be Li3V2(PO4)3) is one of the most attractive cathode materials for primary batteries, which has stable voltage plateaus between 3.0 V and 4.3 V (vs. Li+/Li) and a suitable theoretical specific capacity (133 mA h g\u22121) corresponding to the insertion of two Li ions per formula unit. Most importantly, the unique NASICON structure of Li3V2(PO4)3 facilitates Li+ conduction and delivers faster Li+ diffusion kinetics when compared with traditional cathode materials such as LiFePO4, LiCoO2, and LiNi1/3Co1/3Mn1/3O2, ensuring superior rate capability and low-temperature performance. Thus, LiV2(PO4)3 has great potential for application as a cathode material for lithium primary batteries. For practical application, the shelf life of the Li/LiV2(PO4)3 batteries should be long enough; this means that the self-discharge rate should be as low as possible. Since the Li/LiV2(PO4)3 primary battery possesses a high open-circuit voltage (OCV) of about 4.1 V, the side reactions among electrode materials, electrolyte, and even current collectors can severely affect the shelf life of these batteries. In addition, the corrosion of the current collector leads to self-discharge. Therefore, stabilizing the interface between the electrode and electrolyte is essential.", "question": "What's the cathode?", "answer": "LiFePO4, LiCoO2, and LiNi1/3Co1/3Mn1/3O2", "answer_start": 840}
{"document_id": 75644, "context": "NaxTMO2 type [TM: transition metal(s)] \u2018layered\u2019 oxides, having an initial Na-content (x) of \u223c1 (i.e., \u2018O3\u2019), are important as potential cathode materials for upcoming Na-ion battery systems. However, among other problems (viz., phase transformations during Na-removal/insertion, TM-dissolution etc.), such oxides suffer from severe instability against hydration in a generic sense, which in turn, negatively impacts the stability, electrochemical performances and environment/health friendliness. Against this backdrop, we have designed a composition (viz., combination of TM-/non-TM-ions) to address the aforementioned problems, in particular, air/water-instability. Partial/complete substitution of Ti-ions for Mn-ions eliminated the presence of Mn3+ (which dissolves in electrolyte) at the particle surface, suppressed the increment in impedance (as well as voltage hysteresis) during electrochemical cycling and, thus, significantly improved cyclic stability. More importantly, the air/water-stability improved drastically, such that no phase/structural change occurred even after 40 days of air-exposure and 12 h of stirring in water, unlike for predominately Mn-ion containing counterparts, which progressively evolved O\u20323 and P3 phases. In fact, water-stability enabled the usage of environment/health friendly, as well as less expensive, \u2018aqueous-binder\u2019 (viz., Na-alginate) and water (as solvent) for electrode preparation. The as-developed environment/health friendly \u2018aqueous-processed\u2019 electrode also exhibits excellent long-term cyclic stability, with capacity retention being \u223c82% after 100 cycles (\u223c60% after 500 cycles and \u223c56% after 750 cycles) at C/5, along with just \u223c4% capacity fade over the last 250 cycles investigated (viz., cycles 500\u2013750). Such an elimination of requirements for toxic/hazardous-cum-expensive \u2018non-aqueous\u2019 solvents/binders for electrode preparation and the associated learning, in terms of suitable combinations of TM-/non-TM-ions for these oxides in the pursuit of desired structural features, are significant steps towards the development of alkali metal-ion batteries in general.", "question": "What's the cathode?", "answer": "NaxTMO2 ", "answer_start": 0}
{"document_id": 75644, "context": "NaxTMO2 type [TM: transition metal(s)] \u2018layered\u2019 oxides, having an initial Na-content (x) of \u223c1 (i.e., \u2018O3\u2019), are important as potential cathode materials for upcoming Na-ion battery systems. However, among other problems (viz., phase transformations during Na-removal/insertion, TM-dissolution etc.), such oxides suffer from severe instability against hydration in a generic sense, which in turn, negatively impacts the stability, electrochemical performances and environment/health friendliness. Against this backdrop, we have designed a composition (viz., combination of TM-/non-TM-ions) to address the aforementioned problems, in particular, air/water-instability. Partial/complete substitution of Ti-ions for Mn-ions eliminated the presence of Mn3+ (which dissolves in electrolyte) at the particle surface, suppressed the increment in impedance (as well as voltage hysteresis) during electrochemical cycling and, thus, significantly improved cyclic stability. More importantly, the air/water-stability improved drastically, such that no phase/structural change occurred even after 40 days of air-exposure and 12 h of stirring in water, unlike for predominately Mn-ion containing counterparts, which progressively evolved O\u20323 and P3 phases. In fact, water-stability enabled the usage of environment/health friendly, as well as less expensive, \u2018aqueous-binder\u2019 (viz., Na-alginate) and water (as solvent) for electrode preparation. The as-developed environment/health friendly \u2018aqueous-processed\u2019 electrode also exhibits excellent long-term cyclic stability, with capacity retention being \u223c82% after 100 cycles (\u223c60% after 500 cycles and \u223c56% after 750 cycles) at C/5, along with just \u223c4% capacity fade over the last 250 cycles investigated (viz., cycles 500\u2013750). Such an elimination of requirements for toxic/hazardous-cum-expensive \u2018non-aqueous\u2019 solvents/binders for electrode preparation and the associated learning, in terms of suitable combinations of TM-/non-TM-ions for these oxides in the pursuit of desired structural features, are significant steps towards the development of alkali metal-ion batteries in general.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75646, "context": "Although tremendous efforts have resulted in the great advances in recent years, O3-type layered oxide cathode materials have been plagued by the issue of poor thermal stability and structural stability against a humid atmosphere, which are favorable properties for practical application. To confirm the practical acceptability, we first checked the thermal stability and air-stability of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode by comparing it with the Na[Ni0.5Mn0.5]O2 cathode. Differential scanning calorimetry (DSC) was performed to observe the exothermic reactions of the deeply de-sodiated electrodes (highly unstable state) collected from cells charged to 4.3 V (vs. Na/Na+) after the first cycle. The results are plotted in Fig. S15,\u2020 showing both onset temperature of the exothermic reactions and the total specific heat generation. Although a similar amount of Na+ ions (according to charge capacities) was extracted from the crystal structure, the thermal reaction between NaxCa0.01[Ni0.5Mn0.5]O2 and Nax[Ni0.5Mn0.5]O2 (x is close to 0) cathodes was different. In contrast, the Nax[Ni0.5Mn0.5]O2 electrode displayed an exothermic peak at 254.1 \u00b0C with a heat generation of 634.5 J g\u22121, the NaxCa0.01[Ni0.5Mn0.5]O2 electrode showed a lower heat generation of 352 J g\u22121 and an exothermic peak at 258.9 \u00b0C. It should be noted that the thermal reaction is related to the evolution of oxygen from the crystal structure because the oxygen released from the cathode materials can react with the electrolyte solution and undergo a redox reaction. Therefore, it is strongly believed that the improved thermal stability of the Ca-substituted cathode likely resulted from the strong interaction of immobile Ca2+ with O2\u2212, which suppresses the rate of release of thermal oxygen from the highly oxidized cathode material.", "question": "What's the cathode?", "answer": "O3-type layered oxide", "answer_start": 81}
{"document_id": 75646, "context": "Although tremendous efforts have resulted in the great advances in recent years, O3-type layered oxide cathode materials have been plagued by the issue of poor thermal stability and structural stability against a humid atmosphere, which are favorable properties for practical application. To confirm the practical acceptability, we first checked the thermal stability and air-stability of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode by comparing it with the Na[Ni0.5Mn0.5]O2 cathode. Differential scanning calorimetry (DSC) was performed to observe the exothermic reactions of the deeply de-sodiated electrodes (highly unstable state) collected from cells charged to 4.3 V (vs. Na/Na+) after the first cycle. The results are plotted in Fig. S15,\u2020 showing both onset temperature of the exothermic reactions and the total specific heat generation. Although a similar amount of Na+ ions (according to charge capacities) was extracted from the crystal structure, the thermal reaction between NaxCa0.01[Ni0.5Mn0.5]O2 and Nax[Ni0.5Mn0.5]O2 (x is close to 0) cathodes was different. In contrast, the Nax[Ni0.5Mn0.5]O2 electrode displayed an exothermic peak at 254.1 \u00b0C with a heat generation of 634.5 J g\u22121, the NaxCa0.01[Ni0.5Mn0.5]O2 electrode showed a lower heat generation of 352 J g\u22121 and an exothermic peak at 258.9 \u00b0C. It should be noted that the thermal reaction is related to the evolution of oxygen from the crystal structure because the oxygen released from the cathode materials can react with the electrolyte solution and undergo a redox reaction. Therefore, it is strongly believed that the improved thermal stability of the Ca-substituted cathode likely resulted from the strong interaction of immobile Ca2+ with O2\u2212, which suppresses the rate of release of thermal oxygen from the highly oxidized cathode material.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75646, "context": "Although tremendous efforts have resulted in the great advances in recent years, O3-type layered oxide cathode materials have been plagued by the issue of poor thermal stability and structural stability against a humid atmosphere, which are favorable properties for practical application. To confirm the practical acceptability, we first checked the thermal stability and air-stability of the Na0.98Ca0.01[Ni0.5Mn0.5]O2 cathode by comparing it with the Na[Ni0.5Mn0.5]O2 cathode. Differential scanning calorimetry (DSC) was performed to observe the exothermic reactions of the deeply de-sodiated electrodes (highly unstable state) collected from cells charged to 4.3 V (vs. Na/Na+) after the first cycle. The results are plotted in Fig. S15,\u2020 showing both onset temperature of the exothermic reactions and the total specific heat generation. Although a similar amount of Na+ ions (according to charge capacities) was extracted from the crystal structure, the thermal reaction between NaxCa0.01[Ni0.5Mn0.5]O2 and Nax[Ni0.5Mn0.5]O2 (x is close to 0) cathodes was different. In contrast, the Nax[Ni0.5Mn0.5]O2 electrode displayed an exothermic peak at 254.1 \u00b0C with a heat generation of 634.5 J g\u22121, the NaxCa0.01[Ni0.5Mn0.5]O2 electrode showed a lower heat generation of 352 J g\u22121 and an exothermic peak at 258.9 \u00b0C. It should be noted that the thermal reaction is related to the evolution of oxygen from the crystal structure because the oxygen released from the cathode materials can react with the electrolyte solution and undergo a redox reaction. Therefore, it is strongly believed that the improved thermal stability of the Ca-substituted cathode likely resulted from the strong interaction of immobile Ca2+ with O2\u2212, which suppresses the rate of release of thermal oxygen from the highly oxidized cathode material.", "question": "What's the cathode?", "answer": "Na0.98Ca0.01[Ni0.5Mn0.5]O2", "answer_start": 393}
{"document_id": 75647, "context": "On the other hand, the HER and OER are the two half-reactions involved in electrocatalytic water splitting. These hydrogen-based and oxygen-based alkaline electrochemical reactions are often hindered by sluggish kinetics, which leads to a large overpotential and low round-trip efficiency. Enormous effort has been devoted to the development of highly efficient electrocatalysts for the HER and OER based on the structure\u2013activity relationship, to increase the reaction rate and efficiency of the total system. Accordingly, Liu et al. reported AuPtPdRhRu alloy nanoparticles for HER application by an ultrasonication-assisted wet chemical method (Fig. 5a and b). The as-synthesized quinary AuPtPdRhRu nanoparticles on carbon (AuPtPdRhRu/C), whose average diameter is 2.6 \u00b1 0.3 nm, exhibited excellent HER activity and durability in a 1.0 M KOH electrolyte. The required overpotential of AuPtPdRhRu/C to drive a current density of \u221230 mA cm\u22122 was 190 mV, which is smaller than those of quaternary AuPtPdRh/C (260 mV) and ternary AuPtRh/C (600 mV) catalysts. AuPtPdRhRu/C exhibited a lower Tafel slope of 62 mV dec\u22121 compared to AuPtPdRh/C (91 mV dec\u22121), AuPtPd/C (177 mV dec\u22121), and benchmark Pt/C (77 mV dec\u22121) catalysts, indicating its superior activity toward the alkaline HER. Moreover, AuPtPdRhRu/C exhibited stable electrocatalytic performance over 8 h, verified by chronopotentiometry at a current density of 100 mA cm\u22122. Likewise, Qiu et al. reported noble-metal free nanoporous HEA catalysts for the OER under alkaline conditions. Quinary nanoporous NiCoFeAlX (np-NiCoFeAlX, X = V, Cr, Mn, Cu, Zr, Nb, Mo) and senary np-MoCuNiCoFeAl catalysts were fabricated by a mechanical alloying and chemical dealloying strategy. Among the catalysts, np-MoNiCoFeAl exhibited the lowest OER overpotential (240 mV) to drive a current density of 10 mA cm\u22122 in a 1.0 M KOH electrolyte. Moreover, the np-MoNiCoFeAl catalyst also showed a smaller Tafel slope of 46 mV dec\u22121, compared to ternary np-NiFeAl (62 mV dec\u22121) and quaternary np-NiCoFeAl (61 mV dec\u22121). Moreover, the quinary np-MoNiCoFeAl exhibited high durability compared to ternary and quaternary catalysts, and retained more than 95% of its initial activity after 2000 potential cycles. Due to the oxidative potential under OER conditions, the surface of np-MoNiCoFeAl might undergo oxidation, forming surface oxides on the HEA surfaces. After a chronopotentiometry test at 20 mA cm\u22122 for 50 h, however, the five elements were still uniformly distributed in np-MoNiCoFeAl, forming a high-entropy-oxide (HEO) skin that exhibits high-entropy driven stability.", "question": "What's the cathode?", "answer": "1.0 M KOH", "answer_start": 834}
{"document_id": 75647, "context": "On the other hand, the HER and OER are the two half-reactions involved in electrocatalytic water splitting. These hydrogen-based and oxygen-based alkaline electrochemical reactions are often hindered by sluggish kinetics, which leads to a large overpotential and low round-trip efficiency. Enormous effort has been devoted to the development of highly efficient electrocatalysts for the HER and OER based on the structure\u2013activity relationship, to increase the reaction rate and efficiency of the total system. Accordingly, Liu et al. reported AuPtPdRhRu alloy nanoparticles for HER application by an ultrasonication-assisted wet chemical method (Fig. 5a and b). The as-synthesized quinary AuPtPdRhRu nanoparticles on carbon (AuPtPdRhRu/C), whose average diameter is 2.6 \u00b1 0.3 nm, exhibited excellent HER activity and durability in a 1.0 M KOH electrolyte. The required overpotential of AuPtPdRhRu/C to drive a current density of \u221230 mA cm\u22122 was 190 mV, which is smaller than those of quaternary AuPtPdRh/C (260 mV) and ternary AuPtRh/C (600 mV) catalysts. AuPtPdRhRu/C exhibited a lower Tafel slope of 62 mV dec\u22121 compared to AuPtPdRh/C (91 mV dec\u22121), AuPtPd/C (177 mV dec\u22121), and benchmark Pt/C (77 mV dec\u22121) catalysts, indicating its superior activity toward the alkaline HER. Moreover, AuPtPdRhRu/C exhibited stable electrocatalytic performance over 8 h, verified by chronopotentiometry at a current density of 100 mA cm\u22122. Likewise, Qiu et al. reported noble-metal free nanoporous HEA catalysts for the OER under alkaline conditions. Quinary nanoporous NiCoFeAlX (np-NiCoFeAlX, X = V, Cr, Mn, Cu, Zr, Nb, Mo) and senary np-MoCuNiCoFeAl catalysts were fabricated by a mechanical alloying and chemical dealloying strategy. Among the catalysts, np-MoNiCoFeAl exhibited the lowest OER overpotential (240 mV) to drive a current density of 10 mA cm\u22122 in a 1.0 M KOH electrolyte. Moreover, the np-MoNiCoFeAl catalyst also showed a smaller Tafel slope of 46 mV dec\u22121, compared to ternary np-NiFeAl (62 mV dec\u22121) and quaternary np-NiCoFeAl (61 mV dec\u22121). Moreover, the quinary np-MoNiCoFeAl exhibited high durability compared to ternary and quaternary catalysts, and retained more than 95% of its initial activity after 2000 potential cycles. Due to the oxidative potential under OER conditions, the surface of np-MoNiCoFeAl might undergo oxidation, forming surface oxides on the HEA surfaces. After a chronopotentiometry test at 20 mA cm\u22122 for 50 h, however, the five elements were still uniformly distributed in np-MoNiCoFeAl, forming a high-entropy-oxide (HEO) skin that exhibits high-entropy driven stability.", "question": "What's the cathode?", "answer": "1.0 M KOH", "answer_start": 1855}
{"document_id": 75655, "context": "Lithium sulfur batteries (LSBs) with high theoretical energy densities of 2600 W h kg\u22121 are considered promising candidates to take precedence over lithium ion batteries (LIBs) in meeting the emerging and demanding applications, such as electric vehicles and smart grids. However, the practical implementation of LSBs is plagued by several fundamental challenges, including the dissolution and shuttling of lithium polysulfides (LPSs), the insulating nature of sulfur and lithium sulfides, and the instability of Li metal anodes. In the past decade, progress in structural design and materials chemistry has induced discernible improvements in battery performance. For instance, a high sulfur utilization of 1620 mA h g\u22121 with long cycle life of 1000 cycles was reported for sulfur/graphene composite electrodes. However, statistical analysis of the reported cathodes indicates that the major cathodes tested under low sulfur loadings (<2 mg cm\u22122) and high electrolyte/sulfur (E/S) ratios (>10 \u03bcL mg\u22121) are unacceptable for practical applications. Based on theoretical estimations, LSBs should possess sulfur loadings of above 7 mg cm\u22122, areal capacities of over 6 mA h cm\u22122, and E/S ratios of less than 5 \u03bcL mg\u22121, to outperform current LIBs in terms of the practical energy density.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75656, "context": "Over the past several decades, rechargeable lithium-ion batteries (LIBs) have been widely used in the energy storage market of portable electronic devices and electric vehicles. However, the scarcity and rising costs of Li raw materials have restricted the further large-scale commercialization of LIBs, and thus have spurred extensive research in seeking cost-effective and more reliable energy storage systems. Among various promising alternatives, Na-ion batteries (NIBs) have attracted considerable attention because of the high abundance and low cost of Na resources. Of various anode candidates for NIBs, Na metal anodes are prized for their high specific capacity (1166 mA h g\u22121) and low electrochemical potential (\u22122.714 V vs. standard hydrogen electrode). However, the naturally formed solid electrolyte interphase (SEI) that originates from the instantaneous reaction between the highly reactive Na and electrolyte solvents is generally non-uniform and fragile. The heterogeneous feature easily causes uneven Na deposition and the formation of Na dendrites, and thus brings about serious safety issues. Additionally, the fragile SEI cannot tolerate huge volume changes upon the repetitive plating/stripping process, which gives rise to repeated breakdown/repair of the SEI, leading to a low coulombic efficiency (CE) and short cycle life. These issues impede the practical applications of Na metal anodes.", "question": "What's the anode?", "answer": "Na metal ", "answer_start": 611}
{"document_id": 75656, "context": "Over the past several decades, rechargeable lithium-ion batteries (LIBs) have been widely used in the energy storage market of portable electronic devices and electric vehicles. However, the scarcity and rising costs of Li raw materials have restricted the further large-scale commercialization of LIBs, and thus have spurred extensive research in seeking cost-effective and more reliable energy storage systems. Among various promising alternatives, Na-ion batteries (NIBs) have attracted considerable attention because of the high abundance and low cost of Na resources. Of various anode candidates for NIBs, Na metal anodes are prized for their high specific capacity (1166 mA h g\u22121) and low electrochemical potential (\u22122.714 V vs. standard hydrogen electrode). However, the naturally formed solid electrolyte interphase (SEI) that originates from the instantaneous reaction between the highly reactive Na and electrolyte solvents is generally non-uniform and fragile. The heterogeneous feature easily causes uneven Na deposition and the formation of Na dendrites, and thus brings about serious safety issues. Additionally, the fragile SEI cannot tolerate huge volume changes upon the repetitive plating/stripping process, which gives rise to repeated breakdown/repair of the SEI, leading to a low coulombic efficiency (CE) and short cycle life. These issues impede the practical applications of Na metal anodes.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75656, "context": "Over the past several decades, rechargeable lithium-ion batteries (LIBs) have been widely used in the energy storage market of portable electronic devices and electric vehicles. However, the scarcity and rising costs of Li raw materials have restricted the further large-scale commercialization of LIBs, and thus have spurred extensive research in seeking cost-effective and more reliable energy storage systems. Among various promising alternatives, Na-ion batteries (NIBs) have attracted considerable attention because of the high abundance and low cost of Na resources. Of various anode candidates for NIBs, Na metal anodes are prized for their high specific capacity (1166 mA h g\u22121) and low electrochemical potential (\u22122.714 V vs. standard hydrogen electrode). However, the naturally formed solid electrolyte interphase (SEI) that originates from the instantaneous reaction between the highly reactive Na and electrolyte solvents is generally non-uniform and fragile. The heterogeneous feature easily causes uneven Na deposition and the formation of Na dendrites, and thus brings about serious safety issues. Additionally, the fragile SEI cannot tolerate huge volume changes upon the repetitive plating/stripping process, which gives rise to repeated breakdown/repair of the SEI, leading to a low coulombic efficiency (CE) and short cycle life. These issues impede the practical applications of Na metal anodes.", "question": "What's the anode?", "answer": "Na metal", "answer_start": 1399}
{"document_id": 75657, "context": "To quantitatively evaluate the ECD performance, the difference (\u0394T) in transmittance values in coloured (TC) and bleached (TB) states is defined as below: The measurement results regarding the visible light transmittance of the ECDs under coloured and bleached states according to various UV curing times of 0, 5, 10, and 20 minutes are presented in Fig. 3a and Fig. S4 (ESI\u2020). To assess the \u0394T value, the transmittance values at a wavelength of 550 nm were chosen (Fig. 3b). For the ECD with 5 min of curing, the \u0394T was reduced from 54.7% to 51.7%, as shown in Fig. 3b and Table 1. As the UV curing time was delayed, the \u0394T values were slightly decreased to approximately 50.0% primarily owing to the increased TC value. This suggests that the UV curing process can deteriorate the EC performance of ECDs. It could be inferred that immobile PMMA molecules block many of the reaction sites on the surfaces of both the electrodes. Fig. 3c shows the dynamic spectra of the UV-cured EDCs at a wavelength of 550 nm under a periodic bias voltage between \u22121.2 and 0 V. The reliabilities of all the UV-cured ECDs were maintained for the first five cycles, which is comparable to that of uncured ECD using the liquid electrolyte. Furthermore, their low driving voltage of \u22121.2 V and natural state (0 V) bleaching characteristics are beneficial for low-power devices such as Internet of Things (IoT) devices and wearable displays.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75660, "context": "Besides NiFe-based catalysts, the performance of transition metal sulfides can also be enhanced by Fe incorporation, similar to the effect of Fe-ion doping. For instance, Liu's group reported a novel HER candidate, namely, a Fe-doped NiS2 nanosheet, with high activity and long-time durability. The theoretical and experimental results show that Fe3+ doping into the surface lattice of the NiS2 (002) crystal plane can reduce the activation energy of H2 formation. Further, Fe-doped NiS2 nanosheets can be a bifunctional electrocatalyst with high activities toward both OER and HER in the same media. Sun's group reported the exploitation of iron-doped nickel disulfide nanoarrays on Ti substrate via subsequent sulfidation treatment and used it as a bifunctional electrocatalyst with overall water-splitting capacity. In addition, Cao's group prepared a vertically oriented Fe-doped Ni3S2-nanosheet-based bifunctional electrocatalyst toward both HER and OER with outstanding activity and stability in alkaline electrolytes. Based on detailed experiments and theoretical simulations, it was proved that the electrochemically active surface area, water adsorption ability, and hydrogen adsorption energy of Ni3S2 can be regulated via Fe doping (Fig. 5). For transition metal selenides, the effect of Fe incorporation is also evident. Yu and co-workers described ultrathin Fe-doped NiSe2 nanowires (diameter: <1.7 nm) via a soft-template-mediated colloidal synthesis strategy, further revealing the amorphous hydroxide layers formed in situ that contributed toward the enhanced OER activity. Moreover, Zhao et al. incorporated both Fe dopants and Co vacancies into atomically thin CoSe2 nanobelts for oxygen evolution catalysis, and the resultant CoSe2\u2013DFe\u2013VCo exhibits much higher catalytic activity than other defect-activated CoSe2 and previously reported FeCo compounds. Deeper characterizations and theoretical calculations identify the most active centers of Co2 sites that are adjacent to the VCo-nearest Fe site. Fe doping and Co vacancy can synergistically tune the electronic states of Co2 to a near-optimal value, resulting in considerably decreased binding energy of OH* and consequently lowering the catalytic overpotential.", "question": "What's the electrolyte?", "answer": "alkaline ", "answer_start": 1002}
{"document_id": 75648, "context": "Typical NASICON compounds (such as a NVP cathode and a NTP anode) suffering from severe performance degradation in aqueous electrolytes were employed. The crystal structures, X-ray diffraction (XRD) patterns and SEM images of the prepared NVP/C and NTP/C are shown in Fig. S7.\u2020 In Fig. S8,\u2020 all of the materials have two featured Raman shifts, in which the G-band (ordered graphitic structure) peak is at 1590 cm\u22121 and the D-band (disordered portion) is at 1352 cm\u22121. The thin carbon layer provides good electro-conductivity to NVP/C and NTP/C. In addition, the carbon content of the NVP/C and NTP/C composites measured by elemental analysis (Table S2\u2020) and TG analysis (Fig. S9\u2020) is approximately 3.5 wt%.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75648, "context": "Typical NASICON compounds (such as a NVP cathode and a NTP anode) suffering from severe performance degradation in aqueous electrolytes were employed. The crystal structures, X-ray diffraction (XRD) patterns and SEM images of the prepared NVP/C and NTP/C are shown in Fig. S7.\u2020 In Fig. S8,\u2020 all of the materials have two featured Raman shifts, in which the G-band (ordered graphitic structure) peak is at 1590 cm\u22121 and the D-band (disordered portion) is at 1352 cm\u22121. The thin carbon layer provides good electro-conductivity to NVP/C and NTP/C. In addition, the carbon content of the NVP/C and NTP/C composites measured by elemental analysis (Table S2\u2020) and TG analysis (Fig. S9\u2020) is approximately 3.5 wt%.", "question": "What's the anode?", "answer": "NTP", "answer_start": 55}
{"document_id": 75648, "context": "Typical NASICON compounds (such as a NVP cathode and a NTP anode) suffering from severe performance degradation in aqueous electrolytes were employed. The crystal structures, X-ray diffraction (XRD) patterns and SEM images of the prepared NVP/C and NTP/C are shown in Fig. S7.\u2020 In Fig. S8,\u2020 all of the materials have two featured Raman shifts, in which the G-band (ordered graphitic structure) peak is at 1590 cm\u22121 and the D-band (disordered portion) is at 1352 cm\u22121. The thin carbon layer provides good electro-conductivity to NVP/C and NTP/C. In addition, the carbon content of the NVP/C and NTP/C composites measured by elemental analysis (Table S2\u2020) and TG analysis (Fig. S9\u2020) is approximately 3.5 wt%.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75652, "context": "The nanomesh after galvanostatic EMD deposition is shown in Fig. 2c\u2013e. The electrodeposition resulted in conformal coating of the nanowires with a 8.5 \u00b1 1 nm thick EMD layer. Despite the limited pore size of the nanomesh, the coating was uniformly distributed throughout the depth of the nanowire network, without closing the pores within and at the top of the nanomesh (Fig. 2d). Such open porosity of the cathode is crucial to ensure its high contact area with the battery electrolyte and facilitate transport of Li+ into and out of the electrode. The excellent conformality of EMD on the nanomesh network can be ascribed to both the relatively slow diffusion of reactants through the growing oxide layer, and the pre-deposited MnO2 seed layer, which increases the homogeneity and coulombic efficiency of EMD electrodeposition. X-ray Photoemission Spectroscopy (XPS) confirmed that the as-deposited EMD consists of hydrated MnO2 (Fig. S2\u2020), in agreement with previous observations on the hydrous nature of pristine EMD deposited from aqueous electrolytes. Note that the total thickness of the EMD-coated 3D electrode is much higher than the maximum attainable thickness of electrodeposited MnO2 on planar electrodes (500 nm on Ni and 1.5 \u03bcm on carbon-coated TiN), where the thicker EMD layers easily delaminate.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75652, "context": "The nanomesh after galvanostatic EMD deposition is shown in Fig. 2c\u2013e. The electrodeposition resulted in conformal coating of the nanowires with a 8.5 \u00b1 1 nm thick EMD layer. Despite the limited pore size of the nanomesh, the coating was uniformly distributed throughout the depth of the nanowire network, without closing the pores within and at the top of the nanomesh (Fig. 2d). Such open porosity of the cathode is crucial to ensure its high contact area with the battery electrolyte and facilitate transport of Li+ into and out of the electrode. The excellent conformality of EMD on the nanomesh network can be ascribed to both the relatively slow diffusion of reactants through the growing oxide layer, and the pre-deposited MnO2 seed layer, which increases the homogeneity and coulombic efficiency of EMD electrodeposition. X-ray Photoemission Spectroscopy (XPS) confirmed that the as-deposited EMD consists of hydrated MnO2 (Fig. S2\u2020), in agreement with previous observations on the hydrous nature of pristine EMD deposited from aqueous electrolytes. Note that the total thickness of the EMD-coated 3D electrode is much higher than the maximum attainable thickness of electrodeposited MnO2 on planar electrodes (500 nm on Ni and 1.5 \u03bcm on carbon-coated TiN), where the thicker EMD layers easily delaminate.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75653, "context": "On the basis of the change in the direction of the exfoliating voltage, electrochemical exfoliation of 2D antimony, bismuth and their compounds can be divided into DC voltage exfoliation and square-wave voltage exfoliation. DC voltage exfoliation uses a DC power supply to provide the voltage, and the voltage direction does not change during the exfoliation process. The process of preparing 2D antimony, bismuth and their compounds by the DC voltage exfoliation method is similar to that of cathode exfoliation graphene. The exfoliation process was conducted by using a large block of antimony or bismuth or its compound as the cathode and platinum wire or foil as the anode and in an organic solution. This process applies a voltage to the bulk of antimony, bismuth and their compounds at the cathode, drives the insertion of cations in the electrolyte, and uses jet force that produces hydrogen to promote the peeling of antimony, bismuth and their compounds. In 2017, Li et al. illustrated the possible mechanism of cathodic exfoliation to prepare 2D Sb nanosheets in 0.5 M Na2SO4 solution. Driven by the voltage, the Na+ intercalation layer that accumulates at the negative electrode enters the interlayer of the bulk Sb crystal. Because a large amount of the Na+ intercalation layer enters the interlayer of the Sb crystal, the exfoliation of Sb is eventually promoted by the expansion force (Fig. 4a). Furthermore, the positive and negative voltage and the size of the electrolyte cations affect the efficiency of exfoliation.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75653, "context": "On the basis of the change in the direction of the exfoliating voltage, electrochemical exfoliation of 2D antimony, bismuth and their compounds can be divided into DC voltage exfoliation and square-wave voltage exfoliation. DC voltage exfoliation uses a DC power supply to provide the voltage, and the voltage direction does not change during the exfoliation process. The process of preparing 2D antimony, bismuth and their compounds by the DC voltage exfoliation method is similar to that of cathode exfoliation graphene. The exfoliation process was conducted by using a large block of antimony or bismuth or its compound as the cathode and platinum wire or foil as the anode and in an organic solution. This process applies a voltage to the bulk of antimony, bismuth and their compounds at the cathode, drives the insertion of cations in the electrolyte, and uses jet force that produces hydrogen to promote the peeling of antimony, bismuth and their compounds. In 2017, Li et al. illustrated the possible mechanism of cathodic exfoliation to prepare 2D Sb nanosheets in 0.5 M Na2SO4 solution. Driven by the voltage, the Na+ intercalation layer that accumulates at the negative electrode enters the interlayer of the bulk Sb crystal. Because a large amount of the Na+ intercalation layer enters the interlayer of the Sb crystal, the exfoliation of Sb is eventually promoted by the expansion force (Fig. 4a). Furthermore, the positive and negative voltage and the size of the electrolyte cations affect the efficiency of exfoliation.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75653, "context": "On the basis of the change in the direction of the exfoliating voltage, electrochemical exfoliation of 2D antimony, bismuth and their compounds can be divided into DC voltage exfoliation and square-wave voltage exfoliation. DC voltage exfoliation uses a DC power supply to provide the voltage, and the voltage direction does not change during the exfoliation process. The process of preparing 2D antimony, bismuth and their compounds by the DC voltage exfoliation method is similar to that of cathode exfoliation graphene. The exfoliation process was conducted by using a large block of antimony or bismuth or its compound as the cathode and platinum wire or foil as the anode and in an organic solution. This process applies a voltage to the bulk of antimony, bismuth and their compounds at the cathode, drives the insertion of cations in the electrolyte, and uses jet force that produces hydrogen to promote the peeling of antimony, bismuth and their compounds. In 2017, Li et al. illustrated the possible mechanism of cathodic exfoliation to prepare 2D Sb nanosheets in 0.5 M Na2SO4 solution. Driven by the voltage, the Na+ intercalation layer that accumulates at the negative electrode enters the interlayer of the bulk Sb crystal. Because a large amount of the Na+ intercalation layer enters the interlayer of the Sb crystal, the exfoliation of Sb is eventually promoted by the expansion force (Fig. 4a). Furthermore, the positive and negative voltage and the size of the electrolyte cations affect the efficiency of exfoliation.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75693, "context": "First, we demonstrate the effect of DBSA as a small molecule electrolyte additive, which enhances the electrochemical doping mechanism and device characteristics of OECTs fabricated from conjugated polymers. We start with P3HT and extend the application to PBTTT and DPPT-TT.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75752, "context": "In summary, a novel NVPF@5% rGO with in situ coated 3D carbon network has been successfully prepared via a two-step solid state CTR method and investigated for use as a cathode material for SIBs. The rGO carbon network architecture in NVPF@5% rGO could effectively construct ionic/electronic pathways and provide sufficient electrode\u2013electrolyte contact area for rapid Na+/e\u2212 transport, which significantly improves the electrochemical performance of NaVPO4F. In addition, the stability of NVPF@5% rGO after long-term cycle testing was revealed by the results of the ex situ XRD and SEM analyses, which demonstrated the stable crystal structure of NaVPO4F and the sturdy construction of a robust carbon network. Furthermore, the results of the EIS, CV at various scan rates and GITT tests were implemented to study the electrode kinetic characteristics of NVPF@5% rGO. More importantly, the HC//NVPF@5% rGO full-cell system was fabricated with an HC anode and NVPF@5% rGO cathode, and exhibited superior high-rate capabilities (e.g., 81.8 mA h g\u22121 at 10C and 61.9 mA h g\u22121 at 20C) and ultralong cycling performance (82.71% capacity retention after 1500 cycles at 5C). Considering the easy synthesis route and impressive results, it is believed that this strategy can inspire the further development of high-rate and long-term cycle life electrode materials for SIBs.", "question": "What's the cathode?", "answer": "NVPF@5% rGO", "answer_start": 20}
{"document_id": 75752, "context": "In summary, a novel NVPF@5% rGO with in situ coated 3D carbon network has been successfully prepared via a two-step solid state CTR method and investigated for use as a cathode material for SIBs. The rGO carbon network architecture in NVPF@5% rGO could effectively construct ionic/electronic pathways and provide sufficient electrode\u2013electrolyte contact area for rapid Na+/e\u2212 transport, which significantly improves the electrochemical performance of NaVPO4F. In addition, the stability of NVPF@5% rGO after long-term cycle testing was revealed by the results of the ex situ XRD and SEM analyses, which demonstrated the stable crystal structure of NaVPO4F and the sturdy construction of a robust carbon network. Furthermore, the results of the EIS, CV at various scan rates and GITT tests were implemented to study the electrode kinetic characteristics of NVPF@5% rGO. More importantly, the HC//NVPF@5% rGO full-cell system was fabricated with an HC anode and NVPF@5% rGO cathode, and exhibited superior high-rate capabilities (e.g., 81.8 mA h g\u22121 at 10C and 61.9 mA h g\u22121 at 20C) and ultralong cycling performance (82.71% capacity retention after 1500 cycles at 5C). Considering the easy synthesis route and impressive results, it is believed that this strategy can inspire the further development of high-rate and long-term cycle life electrode materials for SIBs.", "question": "What's the anode?", "answer": "HC", "answer_start": 947}
{"document_id": 75752, "context": "In summary, a novel NVPF@5% rGO with in situ coated 3D carbon network has been successfully prepared via a two-step solid state CTR method and investigated for use as a cathode material for SIBs. The rGO carbon network architecture in NVPF@5% rGO could effectively construct ionic/electronic pathways and provide sufficient electrode\u2013electrolyte contact area for rapid Na+/e\u2212 transport, which significantly improves the electrochemical performance of NaVPO4F. In addition, the stability of NVPF@5% rGO after long-term cycle testing was revealed by the results of the ex situ XRD and SEM analyses, which demonstrated the stable crystal structure of NaVPO4F and the sturdy construction of a robust carbon network. Furthermore, the results of the EIS, CV at various scan rates and GITT tests were implemented to study the electrode kinetic characteristics of NVPF@5% rGO. More importantly, the HC//NVPF@5% rGO full-cell system was fabricated with an HC anode and NVPF@5% rGO cathode, and exhibited superior high-rate capabilities (e.g., 81.8 mA h g\u22121 at 10C and 61.9 mA h g\u22121 at 20C) and ultralong cycling performance (82.71% capacity retention after 1500 cycles at 5C). Considering the easy synthesis route and impressive results, it is believed that this strategy can inspire the further development of high-rate and long-term cycle life electrode materials for SIBs.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75752, "context": "In summary, a novel NVPF@5% rGO with in situ coated 3D carbon network has been successfully prepared via a two-step solid state CTR method and investigated for use as a cathode material for SIBs. The rGO carbon network architecture in NVPF@5% rGO could effectively construct ionic/electronic pathways and provide sufficient electrode\u2013electrolyte contact area for rapid Na+/e\u2212 transport, which significantly improves the electrochemical performance of NaVPO4F. In addition, the stability of NVPF@5% rGO after long-term cycle testing was revealed by the results of the ex situ XRD and SEM analyses, which demonstrated the stable crystal structure of NaVPO4F and the sturdy construction of a robust carbon network. Furthermore, the results of the EIS, CV at various scan rates and GITT tests were implemented to study the electrode kinetic characteristics of NVPF@5% rGO. More importantly, the HC//NVPF@5% rGO full-cell system was fabricated with an HC anode and NVPF@5% rGO cathode, and exhibited superior high-rate capabilities (e.g., 81.8 mA h g\u22121 at 10C and 61.9 mA h g\u22121 at 20C) and ultralong cycling performance (82.71% capacity retention after 1500 cycles at 5C). Considering the easy synthesis route and impressive results, it is believed that this strategy can inspire the further development of high-rate and long-term cycle life electrode materials for SIBs.", "question": "What's the cathode?", "answer": "NVPF@5% rGO ", "answer_start": 960}
{"document_id": 75753, "context": "Electrochemical measurements. All electrochemical measurements were made using an Autolab potentiostat (PGSTAT) and the custom-made three electrode electrochemical cell. The cells components are as follows: thin film deposited on FTO coated glass (working electrode), platinum dispersed on FTO coated glass (counter electrode), silver (Ag) wire (pseudo reference electrode), and 0.1 M tBuNH PF6 in acetonitrile (inert electrolyte). Cyclic voltammetry was measured by applying an oxidising potential to the working electrode and scanning the potential from \u22120.5 V to 1.2 V vs. Ag at a scan rate of 20 mV s\u22121, followed by reversing the direction. The current response waveform was measured simultaneously. Chronoamperometry was used to oxidise the polymer film during in situ spectroscopy measurements. It was performed by applying an excitation square-wave potential to the working electrode in the following configuration: 0 V for 20 seconds (neutral state), an oxidising potential (Vox) for 40 seconds (oxidised state), and 0 V for 20 seconds (back to neutral state). In situ Raman and UV-vis measurements were taken during the application of an oxidising potential when the current response reached steady state (usually after 5\u201310 seconds).", "question": "What's the electrolyte?", "answer": "0.1 M tBuNH PF6 in acetonitrile", "answer_start": 379}
{"document_id": 75759, "context": "Various approaches have been employed to address these issues through the engineering of ex situ deposited surface coatings, solid electrolyte interphase (SEI) transplantation, electrolyte additives, and 3D host materials. These studies have been largely empirical with limited effort directed towards a fundamental understanding of the interplay between electrolyte composition, SEI formation, and lithium metal morphology. For example, it is important to quantify the amount of lithium lost into the SEI, soluble reduction products, \u201cdead\u201d lithium, and corrosion, and to identify how these loss mechanisms are mitigated by using additives or surface coatings. This knowledge will enable the development of commercially viable solutions. Empirical approaches have had some success in improving coulombic efficiency and cycle life, but in most cases it is unclear which loss mechanism is mitigated and how. We consider understanding these processes mechanistically to be the \u201cHoly Grail\u201d of lithium anode research, knowledge that may be extensible to other battery chemistries.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75759, "context": "Various approaches have been employed to address these issues through the engineering of ex situ deposited surface coatings, solid electrolyte interphase (SEI) transplantation, electrolyte additives, and 3D host materials. These studies have been largely empirical with limited effort directed towards a fundamental understanding of the interplay between electrolyte composition, SEI formation, and lithium metal morphology. For example, it is important to quantify the amount of lithium lost into the SEI, soluble reduction products, \u201cdead\u201d lithium, and corrosion, and to identify how these loss mechanisms are mitigated by using additives or surface coatings. This knowledge will enable the development of commercially viable solutions. Empirical approaches have had some success in improving coulombic efficiency and cycle life, but in most cases it is unclear which loss mechanism is mitigated and how. We consider understanding these processes mechanistically to be the \u201cHoly Grail\u201d of lithium anode research, knowledge that may be extensible to other battery chemistries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75760, "context": "A few investigations are recently reported based on dual redox-additive electrolytes, responsible for improving the capacitive performance via anodic and cathodic redox-active electrolytes at negative and positive electrode interfaces, respectively. For example, Zhong et al. constructed an AC-based supercapacitor with two separate redox-additive gel polymer electrolytes: PVA/H2SO4/HQ (in the anodic region) and PVA/H2SO4/MB (in the cathodic region). This approach enhanced the specific capacitance from \u223c139 F g\u22121 to 563.7 F g\u22121 and specific energy from 4.67 W h kg\u22121 to 18.7 W h kg\u22121. Frackowiak et al. reported a significantly improved supercapacitor performance based on dual redox additives KI and VOSO4 in an aqueous H2SO4 electrolyte, respectively, in anodic and cathodic regions. Similarly, Chun et al. showed the effect of dual redox additives methyl viologen chloride and KBr added into a supporting electrolyte on the supercapacitor performance. In another report, Fan et al. examined the effect of redox additives KI and VOSO4, added together in a PVA/H2SO4 polymer electrolyte. The capacitor based on this electrolyte and AC electrodes offered a significantly higher capacitance of 1232.4 F g\u22121 as compared to that of the PVA/H2SO4 based device (156.4 F g\u22121). The selection of dual redox additives for redox-active electrolytes is based on various factors. Apart from the factors, namely high solubility, reversible electron-transfer kinetics and chemical/electrochemical stability, their different redox potentials are important criteria to choose the dual redox additives. While one additive with a higher potential is used for the positive electrode, the other one functions at the negative electrode. Simultaneous redox processes at two interfaces, during charge and discharge, are responsible for a high value of the overall pseudocapacitance. Based on the same criteria discussed above, the two redox additives DPA and KI are selected in the present study, which have different redox potentials \u223c0.76 V and 0.53 V versus the SHE corresponding to their possible redox reaction(s), respectively.", "question": "What's the electrolyte?", "answer": "PVA/H2SO4/HQ (in the anodic region) and PVA/H2SO4/MB (in the cathodic region)", "answer_start": 374}
{"document_id": 75760, "context": "A few investigations are recently reported based on dual redox-additive electrolytes, responsible for improving the capacitive performance via anodic and cathodic redox-active electrolytes at negative and positive electrode interfaces, respectively. For example, Zhong et al. constructed an AC-based supercapacitor with two separate redox-additive gel polymer electrolytes: PVA/H2SO4/HQ (in the anodic region) and PVA/H2SO4/MB (in the cathodic region). This approach enhanced the specific capacitance from \u223c139 F g\u22121 to 563.7 F g\u22121 and specific energy from 4.67 W h kg\u22121 to 18.7 W h kg\u22121. Frackowiak et al. reported a significantly improved supercapacitor performance based on dual redox additives KI and VOSO4 in an aqueous H2SO4 electrolyte, respectively, in anodic and cathodic regions. Similarly, Chun et al. showed the effect of dual redox additives methyl viologen chloride and KBr added into a supporting electrolyte on the supercapacitor performance. In another report, Fan et al. examined the effect of redox additives KI and VOSO4, added together in a PVA/H2SO4 polymer electrolyte. The capacitor based on this electrolyte and AC electrodes offered a significantly higher capacitance of 1232.4 F g\u22121 as compared to that of the PVA/H2SO4 based device (156.4 F g\u22121). The selection of dual redox additives for redox-active electrolytes is based on various factors. Apart from the factors, namely high solubility, reversible electron-transfer kinetics and chemical/electrochemical stability, their different redox potentials are important criteria to choose the dual redox additives. While one additive with a higher potential is used for the positive electrode, the other one functions at the negative electrode. Simultaneous redox processes at two interfaces, during charge and discharge, are responsible for a high value of the overall pseudocapacitance. Based on the same criteria discussed above, the two redox additives DPA and KI are selected in the present study, which have different redox potentials \u223c0.76 V and 0.53 V versus the SHE corresponding to their possible redox reaction(s), respectively.", "question": "What's the electrolyte?", "answer": "H2SO4", "answer_start": 725}
{"document_id": 75761, "context": "In summary, we have demonstrated a flexible organic\u2013inorganic composite solid electrolyte consisting of polymer PEO, Li salt (LiTFSI), ionic liquid (BMP-TFSI), and the ceramic ion conducting LATP particles. The addition of BMP-TFSI can not only decrease the interface impedance between the polymer matrix and LATP particles, but also enhance the stability of the composite electrolyte and Li metal anode. Benefitting from the synergistic effect of the organic\u2013inorganic complex, the PBL-CSE membrane shows improved electrochemical properties. The ionic conductivity is above 10\u22124 S cm\u22121 at 30 \u00b0C. The electrochemical stability window is up to 5.0V (vs. Li+/Li) and the Li+ transference number is 0.48. The PBL-CSE exhibits superb interface stability and impressive capacity against a Li electrode, as well as effective suppression of Li dendrite growth. The assembled solid-state LiFePO4/Li batteries demonstrated excellent cycling stability with a high specific capacity and very large capacity retention at 0.5C at 45 \u00b0C, as well as 0.3C at 30 \u00b0C. Furthermore, LiFePO4/PBL-CSE/Li all-solid-state pouch cells also demonstrate high flexibility and safety. Thus, this work represents a promising composite electrolyte for high performance, safe and high energy density all-solid-state lithium metal batteries.", "question": "What's the anode?", "answer": "Li metal", "answer_start": 389}
{"document_id": 75761, "context": "In summary, we have demonstrated a flexible organic\u2013inorganic composite solid electrolyte consisting of polymer PEO, Li salt (LiTFSI), ionic liquid (BMP-TFSI), and the ceramic ion conducting LATP particles. The addition of BMP-TFSI can not only decrease the interface impedance between the polymer matrix and LATP particles, but also enhance the stability of the composite electrolyte and Li metal anode. Benefitting from the synergistic effect of the organic\u2013inorganic complex, the PBL-CSE membrane shows improved electrochemical properties. The ionic conductivity is above 10\u22124 S cm\u22121 at 30 \u00b0C. The electrochemical stability window is up to 5.0V (vs. Li+/Li) and the Li+ transference number is 0.48. The PBL-CSE exhibits superb interface stability and impressive capacity against a Li electrode, as well as effective suppression of Li dendrite growth. The assembled solid-state LiFePO4/Li batteries demonstrated excellent cycling stability with a high specific capacity and very large capacity retention at 0.5C at 45 \u00b0C, as well as 0.3C at 30 \u00b0C. Furthermore, LiFePO4/PBL-CSE/Li all-solid-state pouch cells also demonstrate high flexibility and safety. Thus, this work represents a promising composite electrolyte for high performance, safe and high energy density all-solid-state lithium metal batteries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75762, "context": "The charging-discharging and cycling curves were obtained from the hybrid electrolyte cells, as displayed in Fig. 6c and d. The cells were charged/discharged with a constant current density of 0.3 mA cm\u22122 for the first cycle, 0.5 mA cm\u22122 for the second to sixth cycles, 1 mA cm\u22122 for the seventh to eleventh cycles and 1.4 mA cm\u22122 for longer cycles. The charging/discharging voltage profiles in Fig. 6c and d show that the cell with the laser-treated LLZTO sample has a relatively small overpotential even at a high current density of 1.4 mA cm\u22122. This result is consistent with the impedance result in Fig. 6a and b, as evident from the reduction of Nyquist curves. For the polished (pristine) LLZTO cell, the cell voltage was found to be unstable in the charging curve of the 8th cycle, implying the formation of an internal short-circuit caused by the propagation of metallic Li. In contrast, notably, the cell with the laser-treated LLZTO sample showed a stable cycling performance without any short-circuit signals (voltage noise and/or sudden drop) at a constant current density of 1.4 mA cm\u22122. The improved cycling stability of the laser-treated cell was confirmed from the cycling curves shown in Fig. 6e for long-term operation under 1.4 mA cm\u22122. The cell showed an excellent coulombic efficiency of 88.9% for 1st cycle, 100% for 3rd cycle, 100% for 7th cycle, 99.96% for 11th cycle, 99.92% for 50th cycle, 99.92% for 100th cycle, and 99.92% for 160th cycle compared with the conventional LIBs and a remarkable capacity retention of 96.7% over the 160th cycle. The mechanism to enhance the electrochemical performance in the laser-treated cell might be complicated. The surface change of LLZTO after the laser treatment includes the formation of Li2O2 and amorphous garnet, the possible reduction of LiOH and Li2CO3, and the morphological deformation. Based on our electronic structure analysis of the laser-treated LLZTO sample and its reduced electronic conductivity (Fig. S5c\u2020), it is highly possible that the main origin of the remarkable improvement in the cycling stability of the laser-treated cell is the formation of the stable amorphous layer with a wide bandgap, which can significantly suppress the Li dendrite formation.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75762, "context": "The charging-discharging and cycling curves were obtained from the hybrid electrolyte cells, as displayed in Fig. 6c and d. The cells were charged/discharged with a constant current density of 0.3 mA cm\u22122 for the first cycle, 0.5 mA cm\u22122 for the second to sixth cycles, 1 mA cm\u22122 for the seventh to eleventh cycles and 1.4 mA cm\u22122 for longer cycles. The charging/discharging voltage profiles in Fig. 6c and d show that the cell with the laser-treated LLZTO sample has a relatively small overpotential even at a high current density of 1.4 mA cm\u22122. This result is consistent with the impedance result in Fig. 6a and b, as evident from the reduction of Nyquist curves. For the polished (pristine) LLZTO cell, the cell voltage was found to be unstable in the charging curve of the 8th cycle, implying the formation of an internal short-circuit caused by the propagation of metallic Li. In contrast, notably, the cell with the laser-treated LLZTO sample showed a stable cycling performance without any short-circuit signals (voltage noise and/or sudden drop) at a constant current density of 1.4 mA cm\u22122. The improved cycling stability of the laser-treated cell was confirmed from the cycling curves shown in Fig. 6e for long-term operation under 1.4 mA cm\u22122. The cell showed an excellent coulombic efficiency of 88.9% for 1st cycle, 100% for 3rd cycle, 100% for 7th cycle, 99.96% for 11th cycle, 99.92% for 50th cycle, 99.92% for 100th cycle, and 99.92% for 160th cycle compared with the conventional LIBs and a remarkable capacity retention of 96.7% over the 160th cycle. The mechanism to enhance the electrochemical performance in the laser-treated cell might be complicated. The surface change of LLZTO after the laser treatment includes the formation of Li2O2 and amorphous garnet, the possible reduction of LiOH and Li2CO3, and the morphological deformation. Based on our electronic structure analysis of the laser-treated LLZTO sample and its reduced electronic conductivity (Fig. S5c\u2020), it is highly possible that the main origin of the remarkable improvement in the cycling stability of the laser-treated cell is the formation of the stable amorphous layer with a wide bandgap, which can significantly suppress the Li dendrite formation.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75762, "context": "The charging-discharging and cycling curves were obtained from the hybrid electrolyte cells, as displayed in Fig. 6c and d. The cells were charged/discharged with a constant current density of 0.3 mA cm\u22122 for the first cycle, 0.5 mA cm\u22122 for the second to sixth cycles, 1 mA cm\u22122 for the seventh to eleventh cycles and 1.4 mA cm\u22122 for longer cycles. The charging/discharging voltage profiles in Fig. 6c and d show that the cell with the laser-treated LLZTO sample has a relatively small overpotential even at a high current density of 1.4 mA cm\u22122. This result is consistent with the impedance result in Fig. 6a and b, as evident from the reduction of Nyquist curves. For the polished (pristine) LLZTO cell, the cell voltage was found to be unstable in the charging curve of the 8th cycle, implying the formation of an internal short-circuit caused by the propagation of metallic Li. In contrast, notably, the cell with the laser-treated LLZTO sample showed a stable cycling performance without any short-circuit signals (voltage noise and/or sudden drop) at a constant current density of 1.4 mA cm\u22122. The improved cycling stability of the laser-treated cell was confirmed from the cycling curves shown in Fig. 6e for long-term operation under 1.4 mA cm\u22122. The cell showed an excellent coulombic efficiency of 88.9% for 1st cycle, 100% for 3rd cycle, 100% for 7th cycle, 99.96% for 11th cycle, 99.92% for 50th cycle, 99.92% for 100th cycle, and 99.92% for 160th cycle compared with the conventional LIBs and a remarkable capacity retention of 96.7% over the 160th cycle. The mechanism to enhance the electrochemical performance in the laser-treated cell might be complicated. The surface change of LLZTO after the laser treatment includes the formation of Li2O2 and amorphous garnet, the possible reduction of LiOH and Li2CO3, and the morphological deformation. Based on our electronic structure analysis of the laser-treated LLZTO sample and its reduced electronic conductivity (Fig. S5c\u2020), it is highly possible that the main origin of the remarkable improvement in the cycling stability of the laser-treated cell is the formation of the stable amorphous layer with a wide bandgap, which can significantly suppress the Li dendrite formation.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75763, "context": "In general, the solid electrolytes used to develop Na-ion solid state battery systems are based on inorganic solid materials; in particular, oxide-based materials that have high ionic conductivity and are electrochemically and thermally stable are being studied. Among oxide-based materials, Na-\u03b2-alumina materials have been mainly studied. Because of their high ionic conductivity, they have been used in all-solid-state batteries until recently. However, they have the disadvantage of being vulnerable to moisture. Another stable oxide-based material is Na3Zr2Si2PO12 (Na super-ionic conductor, NASICON). NASICON solid electrolytes are promising oxide-based Na-ion conducting materials, with a high ionic conductivity of over 10\u22124 S cm\u22121 at room temperature and stability to air and moisture. NASICON ceramics are electrochemically stable up to 7 V, making them suitable for use in high voltage batteries. Owing to its stability advantages, efforts have been made to use NASICON in solid-state NIB systems. However, there remains a critical problem in the resistance between solid particle interfaces caused by the fragile and rigid nature of the oxide material itself, regardless of how high the pressure of the solid electrolyte powder is, making it difficult to utilize it in a solid-state battery system.", "question": "What's the electrolyte?", "answer": "NASICON", "answer_start": 607}
{"document_id": 75764, "context": "3.2.1 Cyclic voltammetry. CV studies have been performed first to optimize the operating potential difference range of the supercapacitor cells. For this purpose, the CV profiles of a typical cell (Cell#4) have been recorded for varying potential difference ranges as shown in Fig. 4a. A close inspection indicates that CV responses show almost rectangular-box like patterns without much deviation, indicating stable capacitive behavior, for the range from 0 to 2.5 V. Thus, all the cells have been electrochemically characterized up to 2.5 V in two electrode configuration, in the present study. This has been confirmed from GCD studies also, as discussed later. It may be noted that the stability window of the dual redox-active electrolyte film is high (\u223c6.2 V), as discussed above, and the charging voltage of the device is restricted to \u223c2.5 V only. The most possible reason for the limited charging voltage of the device is related to the possible reaction(s) of the electrolyte ions with the surface functional groups (carbonyl, carboxyl, hydroxyl, etc.) attached to the activated carbon electrode surface. The electrochemical performance of all the supercapacitor cells (Cell#1 to Cell#4) has been compared, comparing their CV patterns, recorded at a scan rate of 10 mV s\u22121, as shown in Fig. 4b. Cell#1 (with the GPE without redox additives) shows almost a rectangular pattern, similar to the characteristics of capacitors with carbon electrodes, indicating the dominance of double-layer-type capacitive nature. The CV profiles of Cell#2 and Cell#3 (containing GPEs with single redox additives DPA and KI, respectively) illustrate distinct reversible redox peaks (Fig. 4b). The reversible redox peaks in Cell#2 are associated with the reversible conversion between diphenyl benzidine, DPB (colorless) and DPB (violet), which is initiated after irreversible redox transformation of DPA into DPB (colorless), as shown in the following Scheme (1).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75766, "context": "Electrochromic devices (ECDs) have been widely investigated for application in next-generation displays and smart windows thanks to their highly efficient optical transmittance modulation properties. However, several challenges such as chemical and environmental instabilities and leakage of electrolytes limit their practical applications. In this paper, we report a simple and efficient approach for synthesising ultraviolet (UV)-cured poly(methyl methacrylate) (PMMA) gels that can be used as safe electrolytes. The ECDs fabricated with the 10 min UV-cured PMMA gel electrolyte deliver remarkable device performances with a wide optical transmittance transition (\u0394T) of 51.3% at a wavelength of 550 nm under \u22121.2\u20130 V bias range and fast switching times (\u0394t) of 1.5 s and 2.0 s for bleaching and colouration, respectively. In addition, excellent operational stability of 98.9% after 11500 cycles and environmental stability at a wide temperature range of \u221220 to +70 \u00b0C are exhibited. Moreover, a smart electrochromic window system, including an ECD connected with an Arduino circuit, is developed. These smart windows can change colour by simultaneously monitoring the illumination and UV intensities of sunlight.", "question": "What's the electrolyte?", "answer": "ultraviolet (UV)-cured poly(methyl methacrylate) (PMMA)", "answer_start": 415}
{"document_id": 75766, "context": "Electrochromic devices (ECDs) have been widely investigated for application in next-generation displays and smart windows thanks to their highly efficient optical transmittance modulation properties. However, several challenges such as chemical and environmental instabilities and leakage of electrolytes limit their practical applications. In this paper, we report a simple and efficient approach for synthesising ultraviolet (UV)-cured poly(methyl methacrylate) (PMMA) gels that can be used as safe electrolytes. The ECDs fabricated with the 10 min UV-cured PMMA gel electrolyte deliver remarkable device performances with a wide optical transmittance transition (\u0394T) of 51.3% at a wavelength of 550 nm under \u22121.2\u20130 V bias range and fast switching times (\u0394t) of 1.5 s and 2.0 s for bleaching and colouration, respectively. In addition, excellent operational stability of 98.9% after 11500 cycles and environmental stability at a wide temperature range of \u221220 to +70 \u00b0C are exhibited. Moreover, a smart electrochromic window system, including an ECD connected with an Arduino circuit, is developed. These smart windows can change colour by simultaneously monitoring the illumination and UV intensities of sunlight.", "question": "What's the electrolyte?", "answer": "UV-cured PMMA gel", "answer_start": 551}
{"document_id": 75772, "context": "Li metal is regarded as the best candidate for anode materials because of its high theoretical capacity and negative electrode potential. However, due to the continuous parasitic side reactions and messy growing Li dendrites, the practical use of the Li metal as an anode is seriously limited. An in situ formed artificial solid electrolyte interface (SEI) can commendably solve the above-mentioned problems; however, inevitable cracks and fractures are found during their long-term service due to the existence of inorganic compounds (or alloys) in the artificial-SEI. Herein, a self-repairing alloy for protecting the Li metal anode was prepared via a facile in situ reaction. A long-term cycling life of more than 1800 h and 1400 h was obtained for the self-repairing alloy protected Li metal anode at a practical current density of 2 mA cm\u22122 and 5 mA cm\u22122. Even after increasing the deposition capacity to 15 mA h cm\u22122, no dendrite formation was detected in the self-repairing alloy protective Li anode. This is expected to be a promising strategy in achieving a stable Li metal anode/electrolyte interface and providing a new way of thinking for the development of Li metal batteries.", "question": "What's the anode?", "answer": "Li metal", "answer_start": 0}
{"document_id": 75772, "context": "Li metal is regarded as the best candidate for anode materials because of its high theoretical capacity and negative electrode potential. However, due to the continuous parasitic side reactions and messy growing Li dendrites, the practical use of the Li metal as an anode is seriously limited. An in situ formed artificial solid electrolyte interface (SEI) can commendably solve the above-mentioned problems; however, inevitable cracks and fractures are found during their long-term service due to the existence of inorganic compounds (or alloys) in the artificial-SEI. Herein, a self-repairing alloy for protecting the Li metal anode was prepared via a facile in situ reaction. A long-term cycling life of more than 1800 h and 1400 h was obtained for the self-repairing alloy protected Li metal anode at a practical current density of 2 mA cm\u22122 and 5 mA cm\u22122. Even after increasing the deposition capacity to 15 mA h cm\u22122, no dendrite formation was detected in the self-repairing alloy protective Li anode. This is expected to be a promising strategy in achieving a stable Li metal anode/electrolyte interface and providing a new way of thinking for the development of Li metal batteries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75772, "context": "Li metal is regarded as the best candidate for anode materials because of its high theoretical capacity and negative electrode potential. However, due to the continuous parasitic side reactions and messy growing Li dendrites, the practical use of the Li metal as an anode is seriously limited. An in situ formed artificial solid electrolyte interface (SEI) can commendably solve the above-mentioned problems; however, inevitable cracks and fractures are found during their long-term service due to the existence of inorganic compounds (or alloys) in the artificial-SEI. Herein, a self-repairing alloy for protecting the Li metal anode was prepared via a facile in situ reaction. A long-term cycling life of more than 1800 h and 1400 h was obtained for the self-repairing alloy protected Li metal anode at a practical current density of 2 mA cm\u22122 and 5 mA cm\u22122. Even after increasing the deposition capacity to 15 mA h cm\u22122, no dendrite formation was detected in the self-repairing alloy protective Li anode. This is expected to be a promising strategy in achieving a stable Li metal anode/electrolyte interface and providing a new way of thinking for the development of Li metal batteries.", "question": "What's the anode?", "answer": " Li metal", "answer_start": 250}
{"document_id": 75774, "context": "As indicated by the above results, the Li/Al-ion electrolyte exhibits better cycle stability than the Al-ion electrolyte. To further investigate the electrolytes, the voltammograms of these electrolytes measured at different scan rates were analysed using the Randles\u2013Sevick equation (Fig. S7\u2020). The calculated Li-ion diffusion coefficients are 2.84 \u00d7 10\u221212 cm2 s\u22121 and 7.96 \u00d7 10\u221213 cm2 s\u22121 in the WO3 and the Ti-V2O5 films, and the Al-ion diffusion coefficients are 2.72 \u00d7 10\u221214 cm2 s\u22121 and 7.99 \u00d7 10\u221215 cm2 s\u22121 in the WO3 and the Ti-V2O5 films, respectively. The obtained diffusion coefficients are all two magnitudes lower for Al3+ than Li+, owing to the strong electrostatic interaction between trivalent Al3+ and the host lattice, which slows the ion diffusion in the films. For the mixed Li/Al-ion electrolyte, the obtained diffusion curves are between those of the pure Li-ion electrolyte and the pure Al-ion electrolyte (Fig. S7d, h\u2020). Such a performance is much better compared with the coefficient of pure Al-ions in the films, indicating better ion diffusion in the lattices and promoting the cycle stabilities. Previous reports also indicated that the mixed Li/Al-ion electrolyte can promote the cycling performance in Al-anode batteries. The utilization of mixed ion electrolytes can be a promising direction and deserves further investigation.", "question": "What's the anode?", "answer": "Al", "answer_start": 1231}
{"document_id": 75774, "context": "As indicated by the above results, the Li/Al-ion electrolyte exhibits better cycle stability than the Al-ion electrolyte. To further investigate the electrolytes, the voltammograms of these electrolytes measured at different scan rates were analysed using the Randles\u2013Sevick equation (Fig. S7\u2020). The calculated Li-ion diffusion coefficients are 2.84 \u00d7 10\u221212 cm2 s\u22121 and 7.96 \u00d7 10\u221213 cm2 s\u22121 in the WO3 and the Ti-V2O5 films, and the Al-ion diffusion coefficients are 2.72 \u00d7 10\u221214 cm2 s\u22121 and 7.99 \u00d7 10\u221215 cm2 s\u22121 in the WO3 and the Ti-V2O5 films, respectively. The obtained diffusion coefficients are all two magnitudes lower for Al3+ than Li+, owing to the strong electrostatic interaction between trivalent Al3+ and the host lattice, which slows the ion diffusion in the films. For the mixed Li/Al-ion electrolyte, the obtained diffusion curves are between those of the pure Li-ion electrolyte and the pure Al-ion electrolyte (Fig. S7d, h\u2020). Such a performance is much better compared with the coefficient of pure Al-ions in the films, indicating better ion diffusion in the lattices and promoting the cycle stabilities. Previous reports also indicated that the mixed Li/Al-ion electrolyte can promote the cycling performance in Al-anode batteries. The utilization of mixed ion electrolytes can be a promising direction and deserves further investigation.", "question": "What's the electrolyte?", "answer": "Li/Al-ion", "answer_start": 39}
{"document_id": 75774, "context": "As indicated by the above results, the Li/Al-ion electrolyte exhibits better cycle stability than the Al-ion electrolyte. To further investigate the electrolytes, the voltammograms of these electrolytes measured at different scan rates were analysed using the Randles\u2013Sevick equation (Fig. S7\u2020). The calculated Li-ion diffusion coefficients are 2.84 \u00d7 10\u221212 cm2 s\u22121 and 7.96 \u00d7 10\u221213 cm2 s\u22121 in the WO3 and the Ti-V2O5 films, and the Al-ion diffusion coefficients are 2.72 \u00d7 10\u221214 cm2 s\u22121 and 7.99 \u00d7 10\u221215 cm2 s\u22121 in the WO3 and the Ti-V2O5 films, respectively. The obtained diffusion coefficients are all two magnitudes lower for Al3+ than Li+, owing to the strong electrostatic interaction between trivalent Al3+ and the host lattice, which slows the ion diffusion in the films. For the mixed Li/Al-ion electrolyte, the obtained diffusion curves are between those of the pure Li-ion electrolyte and the pure Al-ion electrolyte (Fig. S7d, h\u2020). Such a performance is much better compared with the coefficient of pure Al-ions in the films, indicating better ion diffusion in the lattices and promoting the cycle stabilities. Previous reports also indicated that the mixed Li/Al-ion electrolyte can promote the cycling performance in Al-anode batteries. The utilization of mixed ion electrolytes can be a promising direction and deserves further investigation.", "question": "What's the electrolyte?", "answer": "Al-ion electrolyte.", "answer_start": 102}
{"document_id": 75775, "context": "In addition, the long-term cycling test at 5C was performed to investigate the cycling performance of all the NVPF-based materials shown in Fig. 3d. The NVPF@5% rGO gave the highest initial discharge capacity of 83.2 mA h g\u22121, compared with the NVPF (74.6 mA h g\u22121), NVPF@2.5% rGO (76.4 mA h g\u22121), and NVPF@7.5% rGO (79.9 mA h g\u22121). It also exhibited an excellent capacity retention of 94.06% after 1000 cycles, achieving a high average coulombic efficiency (CE) of 99.6% throughout. Therefore, apart from its outstanding rate capability, the NVPF@5% rGO also exhibited an extremely durable cycling performance. Furthermore, due to the high conductivity and uniformity of the rGO carbon network, the \u0394V values of NVPF@5% rGO were smaller than that of others in each cycle (inset Fig. 3d). The NVPF@7.5% rGO had a slight increase in polarization compared to the NVPF@5% rGO at 1000 cycles, which could be caused by the uneven carbon network. But the polarization of NVPF increased almost linearly during cycling, which leads to a low CE and poor cycling performance. Moreover, although NVPF@2.5% rGO with an incomplete carbon network can inhibit the increase of polarization before 400 cycles, it still exhibits high polarization after more cycles. The schematic diagram of the Na+ and e\u2212 transport pathways in NVPF@5% rGO is shown in Fig. 3e. As shown, because of the robust 3D continuous conductive network structure, the NVPF@5% rGO could not only achieve a highly efficient, ultrafast and continuous transmission of Na+ and e\u2212, but could also build an effective buffer to accommodate volume changes during charge (desodiation)/discharge (sodiation) processes. In addition, the large specific surface area of the rGO carbon network in NVPF@5% rGO could serve as electrolyte storage micro-pools and transport channels, which could provide sufficient and timely electrolyte replenishment for ultrafast charging/discharging.", "question": "What's the electrolyte?", "answer": "NVPF@5% rGO", "answer_start": 1737}
{"document_id": 75776, "context": "Dr Hongfei Li obtained his B.S. degree and M.S. degree in materials science and engineering from Central South University and Tsinghua University, respectively. After that, he received his PhD degree from City University of Hong Kong. Now, he is an associate professor at Songshan Lake Materials Laboratory. His research focuses on aqueous batteries, flexible and wearable energy storage devices, and polymer electrolytes. He has published more than 68 scientific papers with over 3800 total citations and an h-index of 36.", "question": "What's the electrolyte?", "answer": "polymer ", "answer_start": 401}
{"document_id": 75777, "context": "We are able to clarify that the electrochemical doping of the polymer is still predominantly caused by the formation of ion pairs between charged polymer and PF6\u2212 anions, as DBSA itself causes irreversible doping of the polymer (Fig. 4). Fig. 4a shows the behaviour of DBSA in an electrochemical cell with no other salts present by exposing a P3HT thin film to 0.1 M DBSA in ACN electrolyte and measuring in situ ERRS. We observe the typical hole polaron signature in P3HT even at 0 V, indicating the ability of DBSA to chemically dope the polymer film when no other salts are present. We monitor the CC peak position as a function of oxidising potential and find the doping level has a minor dependence on applied bias indicated by the CC peak downshifting from 1425 cm\u22121 to 1417 cm\u22121 (Fig. 4b); the electric field causes more DBSA anions (dissociated from protons) to drift and penetrate into the P3HT film causing further doping. After discharge (0 V) the film is irreversibly doped and the CC peak position remains at 1417 cm\u22121 (green triangle Fig. 4a). Further evidence for irreversible p-type doping caused by DBSA is provided by changes in the UV-Vis absorbance spectra, HOMO level, and work function (see Fig. S2, ESI\u2020). Thus, we elucidate that the mixed ionic electrolyte (with DBSA and TBA:PF6) causes reversible electrochemical doping of the polymer caused by the formation of ion pairs between charged polymer and PF6\u2212 anions. This suggests that the effect of DBSA in the mixed electrolyte is to modify the interaction between the polymer and the electrolyte allowing electrochemical doping at a lower voltage. DBSA has previously been used as a surfactant added to PEDOT:PSS formulations to improve wettability. We believe that DBSA could be having a similar effect on P3HT, interacting with the polymer and acting as a surfactant to enhance the strength of the interactions between the polymer and the electrolyte. In other words, DBSA may modulate the RED between the polymer and the solvent. We demonstrated the effect of RED between the solvent and the polymer on oxidation onset during cyclic voltammetry measurements: there is a lower RED between DCM and P3HT compared to ACN and P3HT, which results in a reduction in the oxidation onset of 0.28 V (Fig. 2). Thus, the RED between the polymer and the electrolyte solvent appears to influence the injection barrier into the film. By adding DBSA to the electrolyte, it may reduce the RED, thus causing a higher mass in the polymer film (solvent and ions), ultimately decreasing the injection barrier into the film.", "question": "What's the electrolyte?", "answer": "0.1 M DBSA in ACN ", "answer_start": 361}
{"document_id": 75777, "context": "We are able to clarify that the electrochemical doping of the polymer is still predominantly caused by the formation of ion pairs between charged polymer and PF6\u2212 anions, as DBSA itself causes irreversible doping of the polymer (Fig. 4). Fig. 4a shows the behaviour of DBSA in an electrochemical cell with no other salts present by exposing a P3HT thin film to 0.1 M DBSA in ACN electrolyte and measuring in situ ERRS. We observe the typical hole polaron signature in P3HT even at 0 V, indicating the ability of DBSA to chemically dope the polymer film when no other salts are present. We monitor the CC peak position as a function of oxidising potential and find the doping level has a minor dependence on applied bias indicated by the CC peak downshifting from 1425 cm\u22121 to 1417 cm\u22121 (Fig. 4b); the electric field causes more DBSA anions (dissociated from protons) to drift and penetrate into the P3HT film causing further doping. After discharge (0 V) the film is irreversibly doped and the CC peak position remains at 1417 cm\u22121 (green triangle Fig. 4a). Further evidence for irreversible p-type doping caused by DBSA is provided by changes in the UV-Vis absorbance spectra, HOMO level, and work function (see Fig. S2, ESI\u2020). Thus, we elucidate that the mixed ionic electrolyte (with DBSA and TBA:PF6) causes reversible electrochemical doping of the polymer caused by the formation of ion pairs between charged polymer and PF6\u2212 anions. This suggests that the effect of DBSA in the mixed electrolyte is to modify the interaction between the polymer and the electrolyte allowing electrochemical doping at a lower voltage. DBSA has previously been used as a surfactant added to PEDOT:PSS formulations to improve wettability. We believe that DBSA could be having a similar effect on P3HT, interacting with the polymer and acting as a surfactant to enhance the strength of the interactions between the polymer and the electrolyte. In other words, DBSA may modulate the RED between the polymer and the solvent. We demonstrated the effect of RED between the solvent and the polymer on oxidation onset during cyclic voltammetry measurements: there is a lower RED between DCM and P3HT compared to ACN and P3HT, which results in a reduction in the oxidation onset of 0.28 V (Fig. 2). Thus, the RED between the polymer and the electrolyte solvent appears to influence the injection barrier into the film. By adding DBSA to the electrolyte, it may reduce the RED, thus causing a higher mass in the polymer film (solvent and ions), ultimately decreasing the injection barrier into the film.", "question": "What's the electrolyte?", "answer": "(with DBSA and TBA:PF6)", "answer_start": 1281}
{"document_id": 75778, "context": "The cycle stability in terms of the charge capacity for the two kinds of films in the Li/Al-ion electrolyte was also evaluated as shown in Fig. 3a and b (details for the in situ measurement of both the charge capacity and the transmittance are provided in the ESI\u2020). After 1000 cycles, the capacity retention was about 78% for the Ti-V2O5 film and 72% for the WO3 film. The cycle stability in terms of the electrochromic performance is obtained by monitoring the optical contrast between the colored and the bleached state of the films. As shown in Fig. 3c and d, after 1000 cycles, the Ti-V2O5 film still delivered a transmittance contrast of up to 24.8% at 400 nm, and for the WO3 film, a contrast up to 47.4% was delivered at 780 nm. These values show that 69.5% of the optical modulation can be retained for Ti-V2O5 and 65.4% can be retained for the WO3 film after 1000 cycles. As a comparison, the Al-ion electrolyte, which is commonly used in Al-based EES devices, was applied to replace the Li/Al-ion electrolyte. As shown in Fig. S6,\u2020 for both the Ti-V2O5 and the WO3 films, the optical contrast in the transmittance spectra drops rapidly within 100 cycles, indicating that the mixed ion electrolyte effectively promotes the cycle stability of the electrochromic films.", "question": "What's the electrolyte?", "answer": " Li/Al-ion", "answer_start": 85}
{"document_id": 75778, "context": "The cycle stability in terms of the charge capacity for the two kinds of films in the Li/Al-ion electrolyte was also evaluated as shown in Fig. 3a and b (details for the in situ measurement of both the charge capacity and the transmittance are provided in the ESI\u2020). After 1000 cycles, the capacity retention was about 78% for the Ti-V2O5 film and 72% for the WO3 film. The cycle stability in terms of the electrochromic performance is obtained by monitoring the optical contrast between the colored and the bleached state of the films. As shown in Fig. 3c and d, after 1000 cycles, the Ti-V2O5 film still delivered a transmittance contrast of up to 24.8% at 400 nm, and for the WO3 film, a contrast up to 47.4% was delivered at 780 nm. These values show that 69.5% of the optical modulation can be retained for Ti-V2O5 and 65.4% can be retained for the WO3 film after 1000 cycles. As a comparison, the Al-ion electrolyte, which is commonly used in Al-based EES devices, was applied to replace the Li/Al-ion electrolyte. As shown in Fig. S6,\u2020 for both the Ti-V2O5 and the WO3 films, the optical contrast in the transmittance spectra drops rapidly within 100 cycles, indicating that the mixed ion electrolyte effectively promotes the cycle stability of the electrochromic films.", "question": "What's the electrolyte?", "answer": " Al-ion", "answer_start": 902}
{"document_id": 75781, "context": "The wettability of electrodes is well known as an important characteristic governing the interaction between the electrolyte and electrode as well as the charge transfer at the interface. As shown in Fig. S6,\u2020 the water contact angle (WCA) of COG is measured to be 0\u00b0, and the total spreading and penetration time (TSPT) of a water drop is about 3.17 s, indicating the inherent hydrophilicity of the COG. This should be attributed to the presence of some heteroatoms in natural reed straw, leading to heteroatom doping during the carbonization process and hence improved hydrophilicity of carbon materials. In contrast, the TSPT of COG@Zn, porous COG@MnO2 and bulk COG@MnO2 is reduced to 0.92 s, 0.42 s and 0.54 s, respectively. The results indicate that the surface wettability of the electrodes has been enhanced from hydrophilic to super-hydrophilic with the incorporation of MnO2 and Zn nanosheets. As is well known, MnO2 and Zn are inherently hydrophilic. In this case, the nanosheet structure increases the roughness of the material's surface, thereby further improving the hydrophilicity of the material. This favors the accessibility of the electrolyte at the surface of the electrodes and the charge transfer between them, giving rise to enhanced electrochemical performance.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75782, "context": "The Li-metal anode is considered an essential component for obtaining the expected Li\u2013S battery performance. This is because of Li's extremely low negative electrochemical potential, very high theoretical specific capacity, and low density. However, the Li-metal anode has additional issues. Safety concerns arise because of the possibility of cell damage or manufacturing failures due to Li-metal's high reactivity, as well as due to the dendrite formation throughout cycling processes which can cause short circuits if dendrites reach the cathode. The electrolyte (salt and solvent) plays a vital role for rapid lithium transport and providing stability even near the highly reactive lithium surface. At the Li surface, electrolyte decomposition due to reduction reactions triggered by their low electrochemical stability leads to the growth of a multicomponent passivating film. This film, known as the solid electrolyte interphase (SEI) may have beneficial passivation properties, or, quite the opposite, may be a cause of irreversible capacity loss. The specific film behavior depends on its chemical composition, structure, and thickness. Moreover, it has been found the SEI properties depend largely on the solvent, salt, and additives used as well as on the electrode structure. Therefore, understanding the role of the electrolyte in SEI formation and its properties should be a useful strategy for controlling dendrite formation, reducing the effects of anode degradation and stabilizing the surface, thus, potentially improving the performance, cycling and safety of the batteries.", "question": "What's the anode?", "answer": "Li-metal", "answer_start": 4}
{"document_id": 75782, "context": "The Li-metal anode is considered an essential component for obtaining the expected Li\u2013S battery performance. This is because of Li's extremely low negative electrochemical potential, very high theoretical specific capacity, and low density. However, the Li-metal anode has additional issues. Safety concerns arise because of the possibility of cell damage or manufacturing failures due to Li-metal's high reactivity, as well as due to the dendrite formation throughout cycling processes which can cause short circuits if dendrites reach the cathode. The electrolyte (salt and solvent) plays a vital role for rapid lithium transport and providing stability even near the highly reactive lithium surface. At the Li surface, electrolyte decomposition due to reduction reactions triggered by their low electrochemical stability leads to the growth of a multicomponent passivating film. This film, known as the solid electrolyte interphase (SEI) may have beneficial passivation properties, or, quite the opposite, may be a cause of irreversible capacity loss. The specific film behavior depends on its chemical composition, structure, and thickness. Moreover, it has been found the SEI properties depend largely on the solvent, salt, and additives used as well as on the electrode structure. Therefore, understanding the role of the electrolyte in SEI formation and its properties should be a useful strategy for controlling dendrite formation, reducing the effects of anode degradation and stabilizing the surface, thus, potentially improving the performance, cycling and safety of the batteries.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75782, "context": "The Li-metal anode is considered an essential component for obtaining the expected Li\u2013S battery performance. This is because of Li's extremely low negative electrochemical potential, very high theoretical specific capacity, and low density. However, the Li-metal anode has additional issues. Safety concerns arise because of the possibility of cell damage or manufacturing failures due to Li-metal's high reactivity, as well as due to the dendrite formation throughout cycling processes which can cause short circuits if dendrites reach the cathode. The electrolyte (salt and solvent) plays a vital role for rapid lithium transport and providing stability even near the highly reactive lithium surface. At the Li surface, electrolyte decomposition due to reduction reactions triggered by their low electrochemical stability leads to the growth of a multicomponent passivating film. This film, known as the solid electrolyte interphase (SEI) may have beneficial passivation properties, or, quite the opposite, may be a cause of irreversible capacity loss. The specific film behavior depends on its chemical composition, structure, and thickness. Moreover, it has been found the SEI properties depend largely on the solvent, salt, and additives used as well as on the electrode structure. Therefore, understanding the role of the electrolyte in SEI formation and its properties should be a useful strategy for controlling dendrite formation, reducing the effects of anode degradation and stabilizing the surface, thus, potentially improving the performance, cycling and safety of the batteries.", "question": "What's the anode?", "answer": " Li-metal", "answer_start": 253}
{"document_id": 75784, "context": "In order to achieve higher power/energy densities for electrochemical energy storage, dual-ion batteries (DIBs), relying on the migration of both cations and anions to store charge concurrently, have been developed. Compared with lithium ion batteries, dual-ion migration behavior can shorten the charge carrier distance. From a cation perspective, lithium ions, as a charge carrier, have contributed to energy storage for several decades. However, many issues have also been raised, such as safety, excessive resource consumption, and environmental pollution. In the process of searching for substitutes, sodium ions, zinc ions, aluminum ions, and other metal ions have been investigated as charge carriers. Non-lithium electrochemical energy storage systems have shown signs of progress. However, no matter how they were improved, metal dendrites have still remained present during the anodic process. To address this limitation, the non-metal ionic liquid EMIm+[PF6]\u2212 has been employed as an electrolyte to realize charge transport. Unfortunately, due to the larger radius of EMIm+ (vertical: 4.3 \u00c5; horizontal: 7.6 \u00c5), it is not possible for traditional graphite anodes to provide a high intercalation capacity. Selecting new electrode materials to achieve the intercalation/deintercalation of EMIm+ can be a route to overcome this bottleneck limitation.", "question": "What's the anode?", "answer": "graphite ", "answer_start": 1158}
{"document_id": 75784, "context": "In order to achieve higher power/energy densities for electrochemical energy storage, dual-ion batteries (DIBs), relying on the migration of both cations and anions to store charge concurrently, have been developed. Compared with lithium ion batteries, dual-ion migration behavior can shorten the charge carrier distance. From a cation perspective, lithium ions, as a charge carrier, have contributed to energy storage for several decades. However, many issues have also been raised, such as safety, excessive resource consumption, and environmental pollution. In the process of searching for substitutes, sodium ions, zinc ions, aluminum ions, and other metal ions have been investigated as charge carriers. Non-lithium electrochemical energy storage systems have shown signs of progress. However, no matter how they were improved, metal dendrites have still remained present during the anodic process. To address this limitation, the non-metal ionic liquid EMIm+[PF6]\u2212 has been employed as an electrolyte to realize charge transport. Unfortunately, due to the larger radius of EMIm+ (vertical: 4.3 \u00c5; horizontal: 7.6 \u00c5), it is not possible for traditional graphite anodes to provide a high intercalation capacity. Selecting new electrode materials to achieve the intercalation/deintercalation of EMIm+ can be a route to overcome this bottleneck limitation.", "question": "What's the electrolyte?", "answer": "EMIm+[PF6]\u2212", "answer_start": 959}
{"document_id": 75785, "context": "To better visualize the local contact loss distribution around the cathode particles, a single NMC particle and its surrounding voids in the sample cycled 50 times were isolated from the larger volume and are shown in Fig. 4(f). The spherical NMC particle at the center is shown in grey, and the surrounding voids are shown in red. The voids are much more concentrated on the right side of the NMC particle, suggesting that the contact loss areas caused by the cathode particle volume shrinking will mostly be on one side of the particle, rather than uniformly distributed around the particle. This is expected because the presence of voids on one side of the particle is sufficient to release the strain caused by the particle volume change. This concentration of the decohered area in the cathode particle may aggravate its effect on capacity loss as now all the Li ions going in and out of the area under the contact loss have a much larger distance to travel before they reach the solid electrolyte. This is in contrast to if the contact loss area were homogeneously dispersed across the cathode particle. In the latter case, diffusion gradients parallel to the surface, resulting from blocked-out surface area for Li to enter or leave the particle, would rapidly fade out in the cathode particle.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75785, "context": "To better visualize the local contact loss distribution around the cathode particles, a single NMC particle and its surrounding voids in the sample cycled 50 times were isolated from the larger volume and are shown in Fig. 4(f). The spherical NMC particle at the center is shown in grey, and the surrounding voids are shown in red. The voids are much more concentrated on the right side of the NMC particle, suggesting that the contact loss areas caused by the cathode particle volume shrinking will mostly be on one side of the particle, rather than uniformly distributed around the particle. This is expected because the presence of voids on one side of the particle is sufficient to release the strain caused by the particle volume change. This concentration of the decohered area in the cathode particle may aggravate its effect on capacity loss as now all the Li ions going in and out of the area under the contact loss have a much larger distance to travel before they reach the solid electrolyte. This is in contrast to if the contact loss area were homogeneously dispersed across the cathode particle. In the latter case, diffusion gradients parallel to the surface, resulting from blocked-out surface area for Li to enter or leave the particle, would rapidly fade out in the cathode particle.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75789, "context": "Even though the SEI film is supposed to act as an insulator being a barrier for electron transfer, at the initial nucleation stages its structure may favor electron transport. This may occur because of the differences between the amorphous character of nucleating crystals and their bulk theoretical structures, as has been found in some bulk insulator materials where changes in the electronic conductivity were observed in ultra-thin films showing a semiconductor behavior. This capability of conducting electrons of imperfectly formed SEI nuclei and phases could contribute to the growth mechanism that keeps the SEI forming until it reaches hundreds of nanometers. Another important reason for the continuous SEI growth is the presence of radical charged species that result from the SEI reactions and are able to diffuse toward the vicinity of the electrolyte inducing further reactions. Several experimental and theoretical works have studied the various stages of the SEI formation and growth process while other authors have proposed the formation of artificial SEI layers by pretreating the anode before the battery is assembled. For the early stages of the SEI formation it is crucial to improve the understanding of electrolyte decomposition by characterizing the reaction mechanisms of electrolytes typically used in battery systems. It is known that carbonate solvents have low stability when implemented with Li-metal anodes, while ether-based solvents like dimethoxyethane (DME) and dioxalane (DOL) have shown better stability with respect to the Li-metal anode and are frequently used for these battery systems. However, solvent and salt molecules decomposition are still observed and in spite of the advances reached both from experimental and theoretical studies, the mechanisms of these processes are not yet well understood.", "question": "What's the anode?", "answer": "Li-metal", "answer_start": 1423}
{"document_id": 75789, "context": "Even though the SEI film is supposed to act as an insulator being a barrier for electron transfer, at the initial nucleation stages its structure may favor electron transport. This may occur because of the differences between the amorphous character of nucleating crystals and their bulk theoretical structures, as has been found in some bulk insulator materials where changes in the electronic conductivity were observed in ultra-thin films showing a semiconductor behavior. This capability of conducting electrons of imperfectly formed SEI nuclei and phases could contribute to the growth mechanism that keeps the SEI forming until it reaches hundreds of nanometers. Another important reason for the continuous SEI growth is the presence of radical charged species that result from the SEI reactions and are able to diffuse toward the vicinity of the electrolyte inducing further reactions. Several experimental and theoretical works have studied the various stages of the SEI formation and growth process while other authors have proposed the formation of artificial SEI layers by pretreating the anode before the battery is assembled. For the early stages of the SEI formation it is crucial to improve the understanding of electrolyte decomposition by characterizing the reaction mechanisms of electrolytes typically used in battery systems. It is known that carbonate solvents have low stability when implemented with Li-metal anodes, while ether-based solvents like dimethoxyethane (DME) and dioxalane (DOL) have shown better stability with respect to the Li-metal anode and are frequently used for these battery systems. However, solvent and salt molecules decomposition are still observed and in spite of the advances reached both from experimental and theoretical studies, the mechanisms of these processes are not yet well understood.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75789, "context": "Even though the SEI film is supposed to act as an insulator being a barrier for electron transfer, at the initial nucleation stages its structure may favor electron transport. This may occur because of the differences between the amorphous character of nucleating crystals and their bulk theoretical structures, as has been found in some bulk insulator materials where changes in the electronic conductivity were observed in ultra-thin films showing a semiconductor behavior. This capability of conducting electrons of imperfectly formed SEI nuclei and phases could contribute to the growth mechanism that keeps the SEI forming until it reaches hundreds of nanometers. Another important reason for the continuous SEI growth is the presence of radical charged species that result from the SEI reactions and are able to diffuse toward the vicinity of the electrolyte inducing further reactions. Several experimental and theoretical works have studied the various stages of the SEI formation and growth process while other authors have proposed the formation of artificial SEI layers by pretreating the anode before the battery is assembled. For the early stages of the SEI formation it is crucial to improve the understanding of electrolyte decomposition by characterizing the reaction mechanisms of electrolytes typically used in battery systems. It is known that carbonate solvents have low stability when implemented with Li-metal anodes, while ether-based solvents like dimethoxyethane (DME) and dioxalane (DOL) have shown better stability with respect to the Li-metal anode and are frequently used for these battery systems. However, solvent and salt molecules decomposition are still observed and in spite of the advances reached both from experimental and theoretical studies, the mechanisms of these processes are not yet well understood.", "question": "What's the anode?", "answer": " Li-metal", "answer_start": 1561}
{"document_id": 75790, "context": "The electrochemical performance of the 400-KOH-Ti3C2 anode was measured in a three-electrode system with the 2 M H2SO4 solution serving as the electrolyte. To determine the potential range of the 400-KOH-Ti3C2 electrode in this acid electrolyte, the CV curves of the 400-KOH-Ti3C2 electrode were collected in various potential windows of \u22120.7 to 0.3 V, \u22120.6 to 0.3 V, \u22120.5 to 0.3 V and \u22120.4 to 0.3 V (vs. Ag/AgCl) at a scan rate of 5 mV s\u22121 (Fig. S6\u2020). It is found that the potential window of the 400-KOH-Ti3C2 electrode can be stably extended to \u22120.6 V (vs. Ag/AgCl) without the decomposition of the electrolyte. Thus, the potential range of the 400-KOH-Ti3C2 electrode is fixed at \u22120.6\u20130.3 V (vs. Ag/AgCl) in 2 M H2SO4 solution. To further evaluate the stable potential window of the 400-KOH-Ti3C2 electrode, we collected CV curves at various scan rates in the potential window of \u22120.6\u20130.3 V (vs. Ag/AgCl) as shown in Fig. 2a. The shape of CV curves can be well retained even at a high scan rate of 200 mV s\u22121, indicating good rate capability of the 400-KOH-Ti3C2 electrode. Except for CV measurements, the galvanostatic discharge\u2013charge profiles of the 400-KOH-Ti3C2 electrode at various current densities were recorded as displayed in Fig. 2b. The discharge\u2013charge curves exhibit a triangular symmetric shape with an inappreciable deviation, suggesting high reversibility and prominent pseudocapacitive behavior. Based on the above discharge\u2013charge curves, the specific capacitance of the 400-KOH-Ti3C2 electrode is calculated to be 334.5 F g\u22121 at 1 A g\u22121. Even at 100 A g\u22121, the 400-KOH-Ti3C2 electrode still retains a specific capacitance of 93.3 F g\u22121 (Fig. 2c). Such high specific capacitance of the 400-KOH-Ti3C2 electrode should be attributed to the large interlayer distance, which provides more accessible active sites for the electrolyte ionic diffusion and electrochemical reaction. To illustrate this view, EIS measurements were performed at a potential of \u22120.1 V (vs. Ag/AgCl) for the 400-KOH-Ti3C2 electrode. The corresponding Nyquist plot of the 400-KOH-Ti3C2 electrode (Fig. 2d) shows a negligible semicircle and a quite small charge transfer resistance (Rct) of 1.2 \u03a9, which is obviously lower than that of original Ti3C2Tx (1.8 \u03a9, Fig. S7\u2020), revealing a fast ion transport and good electronic conductivity for the 400-KOH-Ti3C2 electrode. The Nyquist plots are fitted with the equivalent circuit model shown in Fig. S8.\u2020 In addition, the 400-KOH-Ti3C2 electrode shows a stable cycle performance at 4 A g\u22121, maintaining a capacitance retention of about 87% over 40000 cycles and almost 100% coulombic efficiency. Such excellent cycling stability is comparable to that of most recently reported electrode materials for supercapacitors (see Table S1\u2020). Furthermore, the SEM images of the 400-KOH-Ti3C2 electrode after 5000 cycles show that the layered structure of 400-KOH-Ti3C2 is well retained after cycling (Fig. S9\u2020). It is noteworthy that the capacitance of the 400-KOH-Ti3C2 electrode decreases significantly in the first few hundred cycles, which is likely related to the phase transition of the electrode material.", "question": "What's the anode?", "answer": "400-KOH-Ti3C2 ", "answer_start": 39}
{"document_id": 75790, "context": "The electrochemical performance of the 400-KOH-Ti3C2 anode was measured in a three-electrode system with the 2 M H2SO4 solution serving as the electrolyte. To determine the potential range of the 400-KOH-Ti3C2 electrode in this acid electrolyte, the CV curves of the 400-KOH-Ti3C2 electrode were collected in various potential windows of \u22120.7 to 0.3 V, \u22120.6 to 0.3 V, \u22120.5 to 0.3 V and \u22120.4 to 0.3 V (vs. Ag/AgCl) at a scan rate of 5 mV s\u22121 (Fig. S6\u2020). It is found that the potential window of the 400-KOH-Ti3C2 electrode can be stably extended to \u22120.6 V (vs. Ag/AgCl) without the decomposition of the electrolyte. Thus, the potential range of the 400-KOH-Ti3C2 electrode is fixed at \u22120.6\u20130.3 V (vs. Ag/AgCl) in 2 M H2SO4 solution. To further evaluate the stable potential window of the 400-KOH-Ti3C2 electrode, we collected CV curves at various scan rates in the potential window of \u22120.6\u20130.3 V (vs. Ag/AgCl) as shown in Fig. 2a. The shape of CV curves can be well retained even at a high scan rate of 200 mV s\u22121, indicating good rate capability of the 400-KOH-Ti3C2 electrode. Except for CV measurements, the galvanostatic discharge\u2013charge profiles of the 400-KOH-Ti3C2 electrode at various current densities were recorded as displayed in Fig. 2b. The discharge\u2013charge curves exhibit a triangular symmetric shape with an inappreciable deviation, suggesting high reversibility and prominent pseudocapacitive behavior. Based on the above discharge\u2013charge curves, the specific capacitance of the 400-KOH-Ti3C2 electrode is calculated to be 334.5 F g\u22121 at 1 A g\u22121. Even at 100 A g\u22121, the 400-KOH-Ti3C2 electrode still retains a specific capacitance of 93.3 F g\u22121 (Fig. 2c). Such high specific capacitance of the 400-KOH-Ti3C2 electrode should be attributed to the large interlayer distance, which provides more accessible active sites for the electrolyte ionic diffusion and electrochemical reaction. To illustrate this view, EIS measurements were performed at a potential of \u22120.1 V (vs. Ag/AgCl) for the 400-KOH-Ti3C2 electrode. The corresponding Nyquist plot of the 400-KOH-Ti3C2 electrode (Fig. 2d) shows a negligible semicircle and a quite small charge transfer resistance (Rct) of 1.2 \u03a9, which is obviously lower than that of original Ti3C2Tx (1.8 \u03a9, Fig. S7\u2020), revealing a fast ion transport and good electronic conductivity for the 400-KOH-Ti3C2 electrode. The Nyquist plots are fitted with the equivalent circuit model shown in Fig. S8.\u2020 In addition, the 400-KOH-Ti3C2 electrode shows a stable cycle performance at 4 A g\u22121, maintaining a capacitance retention of about 87% over 40000 cycles and almost 100% coulombic efficiency. Such excellent cycling stability is comparable to that of most recently reported electrode materials for supercapacitors (see Table S1\u2020). Furthermore, the SEM images of the 400-KOH-Ti3C2 electrode after 5000 cycles show that the layered structure of 400-KOH-Ti3C2 is well retained after cycling (Fig. S9\u2020). It is noteworthy that the capacitance of the 400-KOH-Ti3C2 electrode decreases significantly in the first few hundred cycles, which is likely related to the phase transition of the electrode material.", "question": "What's the electrolyte?", "answer": " 2 M H2SO4 ", "answer_start": 108}
{"document_id": 75792, "context": "Using density functional theory (DFT), we calculated the free energy of hydrogen (\u0394GH) on various coating materials as well as their electronic conductivity, and used these two parameters to screen for the best candidate material. Materials with suitable hydrogen adsorption (neither too strong nor too weak) located at the top of volcano plots would have optimum activity. Hence, materials with either very strong (highly negative \u2212\u0394GH) or very weak bonding (highly positive +\u0394GH) should be ideal candidates to suppress the HER. The high \u0394GH of Al2O3 (Fig. 1b) suggested its suitability whereas TiO2, despite its high \u0394GH, became highly catalytic towards the HER once lithiated into LiTi2O4 (as characterized by a low \u0394GH). This increased catalytic activity according to the degree of lithiation might explain why LTO in non-aqueous batteries effectively catalyzed the decomposition of trace H2O present in electrodes and electrolyte. With a highly negative \u0394GH, ZnO would also serve as a good candidate for HER suppression. However, its high electronic conductivity accelerated the charge transfer between the electrolyte and electrodes, which kinetically favors the electrochemical reduction of water. Conversely, Al2O3 had a large bandgap (5.33 eV) (Fig. 1c), which suggested very poor electrical conductivity that prevented charge transfer, in sharp comparison with the bandgaps of lithiated LiTi2O4 (0 eV) and ZnO (1.48 eV), respectively. In fact, the latter two were well known for their metallic and semiconducting behaviors (Fig. 1d and S1\u2020). Therefore, the insulator Al2O3 would be the best candidate surface for HER suppression.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75793, "context": "To facilitate the practical realization of sodium-ion batteries, the energy density, determined by the output operating voltage and/or capacity, needs to be improved to the level of commercial Li-ion batteries. Herein, O3-type Na0.98Ca0.01[Ni0.5Mn0.5]O2 is synthesized by incorporating Ca2+ into the NaO6 octahedron of Na[Ni0.5Mn0.5]O2 and its potential use as a cathode material for high energy density SIBs is demonstrated. The ionic radius of calcium (\u22481.00 \u00c5) is similar to that of sodium (\u22481.02 \u00c5); hence, it is energetically favorable for calcium to occupy sites in the sodium layers. Within a wide operating voltage range of 2.0\u20134.3 V, O3-type Na0.98Ca0.01[Ni0.5Mn0.5]O2 exhibits a reversible O3\u2013P3\u2013O3 phase transition with small volume changes compared to Ca-free Na[Ni0.5Mn0.5]O2 because of the strong interaction between Ca2+ and O2\u2212 and delivers a high reversible capacity of 209 mA h g\u22121 at 15 mA g\u22121 with improved cycling stability. Moreover, Ca substitution improves the practically useful aspects such as thermal and air stability. A prototype pouch full cell with a hard carbon anode shows an excellent capacity retention of 67% over 300 cycles. Thus, this study provides an efficient and simple method to boost the performance and applicability of layered oxide cathode materials for practical applications.", "question": "What's the cathode?", "answer": "Na[Ni0.5Mn0.5]O2", "answer_start": 319}
{"document_id": 75793, "context": "To facilitate the practical realization of sodium-ion batteries, the energy density, determined by the output operating voltage and/or capacity, needs to be improved to the level of commercial Li-ion batteries. Herein, O3-type Na0.98Ca0.01[Ni0.5Mn0.5]O2 is synthesized by incorporating Ca2+ into the NaO6 octahedron of Na[Ni0.5Mn0.5]O2 and its potential use as a cathode material for high energy density SIBs is demonstrated. The ionic radius of calcium (\u22481.00 \u00c5) is similar to that of sodium (\u22481.02 \u00c5); hence, it is energetically favorable for calcium to occupy sites in the sodium layers. Within a wide operating voltage range of 2.0\u20134.3 V, O3-type Na0.98Ca0.01[Ni0.5Mn0.5]O2 exhibits a reversible O3\u2013P3\u2013O3 phase transition with small volume changes compared to Ca-free Na[Ni0.5Mn0.5]O2 because of the strong interaction between Ca2+ and O2\u2212 and delivers a high reversible capacity of 209 mA h g\u22121 at 15 mA g\u22121 with improved cycling stability. Moreover, Ca substitution improves the practically useful aspects such as thermal and air stability. A prototype pouch full cell with a hard carbon anode shows an excellent capacity retention of 67% over 300 cycles. Thus, this study provides an efficient and simple method to boost the performance and applicability of layered oxide cathode materials for practical applications.", "question": "What's the anode?", "answer": "hard carbon", "answer_start": 1082}
{"document_id": 75793, "context": "To facilitate the practical realization of sodium-ion batteries, the energy density, determined by the output operating voltage and/or capacity, needs to be improved to the level of commercial Li-ion batteries. Herein, O3-type Na0.98Ca0.01[Ni0.5Mn0.5]O2 is synthesized by incorporating Ca2+ into the NaO6 octahedron of Na[Ni0.5Mn0.5]O2 and its potential use as a cathode material for high energy density SIBs is demonstrated. The ionic radius of calcium (\u22481.00 \u00c5) is similar to that of sodium (\u22481.02 \u00c5); hence, it is energetically favorable for calcium to occupy sites in the sodium layers. Within a wide operating voltage range of 2.0\u20134.3 V, O3-type Na0.98Ca0.01[Ni0.5Mn0.5]O2 exhibits a reversible O3\u2013P3\u2013O3 phase transition with small volume changes compared to Ca-free Na[Ni0.5Mn0.5]O2 because of the strong interaction between Ca2+ and O2\u2212 and delivers a high reversible capacity of 209 mA h g\u22121 at 15 mA g\u22121 with improved cycling stability. Moreover, Ca substitution improves the practically useful aspects such as thermal and air stability. A prototype pouch full cell with a hard carbon anode shows an excellent capacity retention of 67% over 300 cycles. Thus, this study provides an efficient and simple method to boost the performance and applicability of layered oxide cathode materials for practical applications.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75795, "context": "To overcome this limitation, analysis of Differential Capacity Plots (DCPs) has been performed to identify electrochemical charge/discharge reactions and track their evolution during cycling. Fig. 6 shows the DCPs for the different Si/Ni\u2013Sn/Al/C composites at cycles 2, 80 and 200 corresponding to composite activation, maximum capacity and end-of-cycling states. For Si-B, at the 2nd lithiation (Fig. 6a), three reduction peaks are observed in the cathodic branch. The peak at 0.17 V is attributed to the reaction potential of amorphous Si with lithium to form LixSi alloys of approximate composition LiSi and Li7Si3. Silicon amorphisation is known to occur during the first lithiation of crystalline Si anodes. The two other reduction peaks at 0.31 and 0.62 V are attributed to the formation of LiySn alloys: Li7Sn2 and LiSn, respectively. On delithiation, multiple oxidation peaks are detected and are attributed to the decomposition of Li7Si3 at 0.51 V and different LiySn alloys: Li7Sn2 (or Li22Sn5), Li5Sn2, LiSn and Li2Sn5 at 0.47, 0.58, 0.74 and 0.81 V, respectively. The two phases Li7Sn3 and Li13Sn5 have compositions close to Li5Sn2 and could be involved in the delithiation process at 0.58 V. For both composites Si-AB and Si-A, poorly defined cathodic peaks are found at the 2nd lithiation, but DCPs exhibit significant features in delithiation. For Si-AB, two oxidation peaks are clearly identified at 0.47 and 0.58 V attributed to the decomposition of Li7Sn2 (or Li22Sn5) and Li5Sn2 alloys, respectively. For Si-A, a unique broad oxidation peak is observed at 0.51 V assigned to the decomposition of Li7Si3. Interestingly, no signal related to the decomposition of LiySn alloys is detected for the composite Si-A, suggesting that Ni3Sn2 does not react with lithium.", "question": "What's the anode?", "answer": "Si ", "answer_start": 702}
{"document_id": 75795, "context": "To overcome this limitation, analysis of Differential Capacity Plots (DCPs) has been performed to identify electrochemical charge/discharge reactions and track their evolution during cycling. Fig. 6 shows the DCPs for the different Si/Ni\u2013Sn/Al/C composites at cycles 2, 80 and 200 corresponding to composite activation, maximum capacity and end-of-cycling states. For Si-B, at the 2nd lithiation (Fig. 6a), three reduction peaks are observed in the cathodic branch. The peak at 0.17 V is attributed to the reaction potential of amorphous Si with lithium to form LixSi alloys of approximate composition LiSi and Li7Si3. Silicon amorphisation is known to occur during the first lithiation of crystalline Si anodes. The two other reduction peaks at 0.31 and 0.62 V are attributed to the formation of LiySn alloys: Li7Sn2 and LiSn, respectively. On delithiation, multiple oxidation peaks are detected and are attributed to the decomposition of Li7Si3 at 0.51 V and different LiySn alloys: Li7Sn2 (or Li22Sn5), Li5Sn2, LiSn and Li2Sn5 at 0.47, 0.58, 0.74 and 0.81 V, respectively. The two phases Li7Sn3 and Li13Sn5 have compositions close to Li5Sn2 and could be involved in the delithiation process at 0.58 V. For both composites Si-AB and Si-A, poorly defined cathodic peaks are found at the 2nd lithiation, but DCPs exhibit significant features in delithiation. For Si-AB, two oxidation peaks are clearly identified at 0.47 and 0.58 V attributed to the decomposition of Li7Sn2 (or Li22Sn5) and Li5Sn2 alloys, respectively. For Si-A, a unique broad oxidation peak is observed at 0.51 V assigned to the decomposition of Li7Si3. Interestingly, no signal related to the decomposition of LiySn alloys is detected for the composite Si-A, suggesting that Ni3Sn2 does not react with lithium.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75796, "context": "A sodium-based analog of 3a, i.e. sodium rhodizonate 3b, was tested by Goodenough et al. with an anode based on a liquid sodium\u2013potassium alloy (NaK). The advantage of this anode is its dendrite-free nature, making it safer compared to pristine potassium. In a DME-based KFSI solution, Qm was \u223c120 mA h g\u22121 at 125 mA g\u22121, with \u223c50 mA h g\u22121 delivered at 1.25 A g\u22121. The capacity retention was ca. 75% after 100 cycles.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75796, "context": "A sodium-based analog of 3a, i.e. sodium rhodizonate 3b, was tested by Goodenough et al. with an anode based on a liquid sodium\u2013potassium alloy (NaK). The advantage of this anode is its dendrite-free nature, making it safer compared to pristine potassium. In a DME-based KFSI solution, Qm was \u223c120 mA h g\u22121 at 125 mA g\u22121, with \u223c50 mA h g\u22121 delivered at 1.25 A g\u22121. The capacity retention was ca. 75% after 100 cycles.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75797, "context": "The Zn symmetric and Zn\u2013Ti asymmetric cells were assembled as CR2030 coin cells to measure the electrochemical performances. Glass fiber and a 3 M Zn(CF3SO3)2 aqueous solution were used as the separator and the electrolyte, respectively. Before cell fabrication, Ti foil, bare Zn foil and PAM/PVP-coated Zn were cut into disk-shaped electrodes. The symmetric cells consist of two bare Zn foils (or PAM/PVP-coated Zn foils) separated by a glass fiber separator. The cells underwent galvanostatic charge and discharge cycling at a current density of 0.2\u201310 mA cm\u22122 on a Neware battery testing instrument. These experiments were performed to evaluate the stripping/plating behavior and cycling stability of the bare Zn and PAM/PVP-coated Zn anodes. Furthermore, Zn\u2013Ti asymmetric cells were fabricated to investigate the coulombic efficiency of Zn stripping/plating. The asymmetric cell was initially discharged for 10 min, and then to 2.0 V at various current densities from 0.2\u201320 mA cm\u22122. To obtain the corrosion potential (Ecorr) and corrosion current density (Icorr), Tafel plots of the Zn symmetric cells were recorded on an electrochemical workstation (CHI660E, China) at a scan rate of 10 mV s\u22121. Chronoamperograms (CAs) of the bare Zn and the PAM/PVP-coated Zn symmetric cells were recorded under a \u2212200 mV overpotential. The Zn\u2013AC hybrid supercapacitors were fabricated with AC as the cathode, bare Zn or PAM/PVP-coated Zn foil as the anode, and 3 M Zn(CF3SO3)2 aqueous solution as the electrolyte. The cathode slurry was fabricated by mixing the cathode active materials, Super P, and PTFE at a mass ratio of 80:10:10. The resulting slurry was rolled into a thin film with a thickness of about 120 \u03bcm. Finally, the film was cut into discs with a diameter of 10 mm, pressed into a Ti mesh (15 mm in diameter) and dried in a vacuum oven at 100 \u00b0C for 6 h. The electrochemical performance was evaluated by cyclic voltammetry on an electrochemical workstation. The galvanostatic charge\u2013discharge processes of the Zn\u2013AC hybrid supercapacitor were recorded on a Neware battery testing system.", "question": "What's the cathode?", "answer": "AC ", "answer_start": 1381}
{"document_id": 75797, "context": "The Zn symmetric and Zn\u2013Ti asymmetric cells were assembled as CR2030 coin cells to measure the electrochemical performances. Glass fiber and a 3 M Zn(CF3SO3)2 aqueous solution were used as the separator and the electrolyte, respectively. Before cell fabrication, Ti foil, bare Zn foil and PAM/PVP-coated Zn were cut into disk-shaped electrodes. The symmetric cells consist of two bare Zn foils (or PAM/PVP-coated Zn foils) separated by a glass fiber separator. The cells underwent galvanostatic charge and discharge cycling at a current density of 0.2\u201310 mA cm\u22122 on a Neware battery testing instrument. These experiments were performed to evaluate the stripping/plating behavior and cycling stability of the bare Zn and PAM/PVP-coated Zn anodes. Furthermore, Zn\u2013Ti asymmetric cells were fabricated to investigate the coulombic efficiency of Zn stripping/plating. The asymmetric cell was initially discharged for 10 min, and then to 2.0 V at various current densities from 0.2\u201320 mA cm\u22122. To obtain the corrosion potential (Ecorr) and corrosion current density (Icorr), Tafel plots of the Zn symmetric cells were recorded on an electrochemical workstation (CHI660E, China) at a scan rate of 10 mV s\u22121. Chronoamperograms (CAs) of the bare Zn and the PAM/PVP-coated Zn symmetric cells were recorded under a \u2212200 mV overpotential. The Zn\u2013AC hybrid supercapacitors were fabricated with AC as the cathode, bare Zn or PAM/PVP-coated Zn foil as the anode, and 3 M Zn(CF3SO3)2 aqueous solution as the electrolyte. The cathode slurry was fabricated by mixing the cathode active materials, Super P, and PTFE at a mass ratio of 80:10:10. The resulting slurry was rolled into a thin film with a thickness of about 120 \u03bcm. Finally, the film was cut into discs with a diameter of 10 mm, pressed into a Ti mesh (15 mm in diameter) and dried in a vacuum oven at 100 \u00b0C for 6 h. The electrochemical performance was evaluated by cyclic voltammetry on an electrochemical workstation. The galvanostatic charge\u2013discharge processes of the Zn\u2013AC hybrid supercapacitor were recorded on a Neware battery testing system.", "question": "What's the anode?", "answer": "the bare Zn and PAM/PVP-coated Zn", "answer_start": 704}
{"document_id": 75797, "context": "The Zn symmetric and Zn\u2013Ti asymmetric cells were assembled as CR2030 coin cells to measure the electrochemical performances. Glass fiber and a 3 M Zn(CF3SO3)2 aqueous solution were used as the separator and the electrolyte, respectively. Before cell fabrication, Ti foil, bare Zn foil and PAM/PVP-coated Zn were cut into disk-shaped electrodes. The symmetric cells consist of two bare Zn foils (or PAM/PVP-coated Zn foils) separated by a glass fiber separator. The cells underwent galvanostatic charge and discharge cycling at a current density of 0.2\u201310 mA cm\u22122 on a Neware battery testing instrument. These experiments were performed to evaluate the stripping/plating behavior and cycling stability of the bare Zn and PAM/PVP-coated Zn anodes. Furthermore, Zn\u2013Ti asymmetric cells were fabricated to investigate the coulombic efficiency of Zn stripping/plating. The asymmetric cell was initially discharged for 10 min, and then to 2.0 V at various current densities from 0.2\u201320 mA cm\u22122. To obtain the corrosion potential (Ecorr) and corrosion current density (Icorr), Tafel plots of the Zn symmetric cells were recorded on an electrochemical workstation (CHI660E, China) at a scan rate of 10 mV s\u22121. Chronoamperograms (CAs) of the bare Zn and the PAM/PVP-coated Zn symmetric cells were recorded under a \u2212200 mV overpotential. The Zn\u2013AC hybrid supercapacitors were fabricated with AC as the cathode, bare Zn or PAM/PVP-coated Zn foil as the anode, and 3 M Zn(CF3SO3)2 aqueous solution as the electrolyte. The cathode slurry was fabricated by mixing the cathode active materials, Super P, and PTFE at a mass ratio of 80:10:10. The resulting slurry was rolled into a thin film with a thickness of about 120 \u03bcm. Finally, the film was cut into discs with a diameter of 10 mm, pressed into a Ti mesh (15 mm in diameter) and dried in a vacuum oven at 100 \u00b0C for 6 h. The electrochemical performance was evaluated by cyclic voltammetry on an electrochemical workstation. The galvanostatic charge\u2013discharge processes of the Zn\u2013AC hybrid supercapacitor were recorded on a Neware battery testing system.", "question": "What's the electrolyte?", "answer": "3 M Zn(CF3SO3)2 aqueous solution", "answer_start": 143}
{"document_id": 75797, "context": "The Zn symmetric and Zn\u2013Ti asymmetric cells were assembled as CR2030 coin cells to measure the electrochemical performances. Glass fiber and a 3 M Zn(CF3SO3)2 aqueous solution were used as the separator and the electrolyte, respectively. Before cell fabrication, Ti foil, bare Zn foil and PAM/PVP-coated Zn were cut into disk-shaped electrodes. The symmetric cells consist of two bare Zn foils (or PAM/PVP-coated Zn foils) separated by a glass fiber separator. The cells underwent galvanostatic charge and discharge cycling at a current density of 0.2\u201310 mA cm\u22122 on a Neware battery testing instrument. These experiments were performed to evaluate the stripping/plating behavior and cycling stability of the bare Zn and PAM/PVP-coated Zn anodes. Furthermore, Zn\u2013Ti asymmetric cells were fabricated to investigate the coulombic efficiency of Zn stripping/plating. The asymmetric cell was initially discharged for 10 min, and then to 2.0 V at various current densities from 0.2\u201320 mA cm\u22122. To obtain the corrosion potential (Ecorr) and corrosion current density (Icorr), Tafel plots of the Zn symmetric cells were recorded on an electrochemical workstation (CHI660E, China) at a scan rate of 10 mV s\u22121. Chronoamperograms (CAs) of the bare Zn and the PAM/PVP-coated Zn symmetric cells were recorded under a \u2212200 mV overpotential. The Zn\u2013AC hybrid supercapacitors were fabricated with AC as the cathode, bare Zn or PAM/PVP-coated Zn foil as the anode, and 3 M Zn(CF3SO3)2 aqueous solution as the electrolyte. The cathode slurry was fabricated by mixing the cathode active materials, Super P, and PTFE at a mass ratio of 80:10:10. The resulting slurry was rolled into a thin film with a thickness of about 120 \u03bcm. Finally, the film was cut into discs with a diameter of 10 mm, pressed into a Ti mesh (15 mm in diameter) and dried in a vacuum oven at 100 \u00b0C for 6 h. The electrochemical performance was evaluated by cyclic voltammetry on an electrochemical workstation. The galvanostatic charge\u2013discharge processes of the Zn\u2013AC hybrid supercapacitor were recorded on a Neware battery testing system.", "question": "What's the anode?", "answer": "bare Zn or PAM/PVP-coated Zn foil", "answer_start": 1400}
{"document_id": 75797, "context": "The Zn symmetric and Zn\u2013Ti asymmetric cells were assembled as CR2030 coin cells to measure the electrochemical performances. Glass fiber and a 3 M Zn(CF3SO3)2 aqueous solution were used as the separator and the electrolyte, respectively. Before cell fabrication, Ti foil, bare Zn foil and PAM/PVP-coated Zn were cut into disk-shaped electrodes. The symmetric cells consist of two bare Zn foils (or PAM/PVP-coated Zn foils) separated by a glass fiber separator. The cells underwent galvanostatic charge and discharge cycling at a current density of 0.2\u201310 mA cm\u22122 on a Neware battery testing instrument. These experiments were performed to evaluate the stripping/plating behavior and cycling stability of the bare Zn and PAM/PVP-coated Zn anodes. Furthermore, Zn\u2013Ti asymmetric cells were fabricated to investigate the coulombic efficiency of Zn stripping/plating. The asymmetric cell was initially discharged for 10 min, and then to 2.0 V at various current densities from 0.2\u201320 mA cm\u22122. To obtain the corrosion potential (Ecorr) and corrosion current density (Icorr), Tafel plots of the Zn symmetric cells were recorded on an electrochemical workstation (CHI660E, China) at a scan rate of 10 mV s\u22121. Chronoamperograms (CAs) of the bare Zn and the PAM/PVP-coated Zn symmetric cells were recorded under a \u2212200 mV overpotential. The Zn\u2013AC hybrid supercapacitors were fabricated with AC as the cathode, bare Zn or PAM/PVP-coated Zn foil as the anode, and 3 M Zn(CF3SO3)2 aqueous solution as the electrolyte. The cathode slurry was fabricated by mixing the cathode active materials, Super P, and PTFE at a mass ratio of 80:10:10. The resulting slurry was rolled into a thin film with a thickness of about 120 \u03bcm. Finally, the film was cut into discs with a diameter of 10 mm, pressed into a Ti mesh (15 mm in diameter) and dried in a vacuum oven at 100 \u00b0C for 6 h. The electrochemical performance was evaluated by cyclic voltammetry on an electrochemical workstation. The galvanostatic charge\u2013discharge processes of the Zn\u2013AC hybrid supercapacitor were recorded on a Neware battery testing system.", "question": "What's the electrolyte?", "answer": " 3 M Zn(CF3SO3)2 aqueous solution", "answer_start": 1451}
{"document_id": 75800, "context": "Despite the merits of zinc anode, ARZIBs are still at a development stage due to the lack of suitable Zn-ion host materials. To date, various materials have been explored as cathodes for ARZIBs, such as manganese-based oxides, Prussian blue analogues, polyanionic compounds, and vanadium-based compounds. However, most of the reported cathode materials suffer from insufficient rate capability, low capacity, and energy density. The main reasons can be ascribed to three factors: (i) the relativity poor conductivity leads to sluggish ion/electron transport kinetics, especially in quasi-solid-state electrolytes; (ii) the use of non-active additives such as polyvinylidene fluoride and polypyrrole, which were usually employed to ameliorate the flexibility of powder-formed active materials, would inevitably increase the \u201cdead mass\u201d of the cathode, thus limiting the overall energy density of the full devices; (iii) the increased contact resistance between the active materials and the current collector, and the interfacial resistance between the electrode and electrolyte, arising from the repeated reversible Zn2+ (de)intercalation processes, further result in a decrease in the high rate ability. Therefore, there is an urgent demand to explore free-standing materials that can adequately accommodate Zn2+ insertion/extraction rapidly and steadily to promote the progress of ARZIBs.", "question": "What's the cathode?", "answer": "manganese-based oxides, Prussian blue analogues, polyanionic compounds, and vanadium-based compounds", "answer_start": 203}
{"document_id": 75800, "context": "Despite the merits of zinc anode, ARZIBs are still at a development stage due to the lack of suitable Zn-ion host materials. To date, various materials have been explored as cathodes for ARZIBs, such as manganese-based oxides, Prussian blue analogues, polyanionic compounds, and vanadium-based compounds. However, most of the reported cathode materials suffer from insufficient rate capability, low capacity, and energy density. The main reasons can be ascribed to three factors: (i) the relativity poor conductivity leads to sluggish ion/electron transport kinetics, especially in quasi-solid-state electrolytes; (ii) the use of non-active additives such as polyvinylidene fluoride and polypyrrole, which were usually employed to ameliorate the flexibility of powder-formed active materials, would inevitably increase the \u201cdead mass\u201d of the cathode, thus limiting the overall energy density of the full devices; (iii) the increased contact resistance between the active materials and the current collector, and the interfacial resistance between the electrode and electrolyte, arising from the repeated reversible Zn2+ (de)intercalation processes, further result in a decrease in the high rate ability. Therefore, there is an urgent demand to explore free-standing materials that can adequately accommodate Zn2+ insertion/extraction rapidly and steadily to promote the progress of ARZIBs.", "question": "What's the anode?", "answer": "zinc ", "answer_start": 22}
{"document_id": 75800, "context": "Despite the merits of zinc anode, ARZIBs are still at a development stage due to the lack of suitable Zn-ion host materials. To date, various materials have been explored as cathodes for ARZIBs, such as manganese-based oxides, Prussian blue analogues, polyanionic compounds, and vanadium-based compounds. However, most of the reported cathode materials suffer from insufficient rate capability, low capacity, and energy density. The main reasons can be ascribed to three factors: (i) the relativity poor conductivity leads to sluggish ion/electron transport kinetics, especially in quasi-solid-state electrolytes; (ii) the use of non-active additives such as polyvinylidene fluoride and polypyrrole, which were usually employed to ameliorate the flexibility of powder-formed active materials, would inevitably increase the \u201cdead mass\u201d of the cathode, thus limiting the overall energy density of the full devices; (iii) the increased contact resistance between the active materials and the current collector, and the interfacial resistance between the electrode and electrolyte, arising from the repeated reversible Zn2+ (de)intercalation processes, further result in a decrease in the high rate ability. Therefore, there is an urgent demand to explore free-standing materials that can adequately accommodate Zn2+ insertion/extraction rapidly and steadily to promote the progress of ARZIBs.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75801, "context": "The electrochemical performance of the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors was tested by cyclic voltammetry and galvanostatic charge\u2013discharge tests within the voltage range of 0\u20132.0 V (Fig. 5). The CV curves of the hybrid ion capacitors at various scan rates from 10 mV s\u22121 to 200 mV s\u22121 maintain a quasi-rectangular shape, suggesting an EDLC-type behavior (Fig. 5a). Fig. 5b shows the voltage curves of the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors at various current densities from 0.5\u201330 A g\u22121. The symmetric and linear shape of the curves in the graph can be observed corresponding to the results of the CV test. At a current density of 1 A g\u22121, the bare Zn\u2013AC hybrid ion supercapacitors failed after 10 cycles, while the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors show a good cycling stability (Fig. S10\u2020). This superior stability can be attributed to the critical role of the PAM/PVP layer coated on the zinc anode acting as an inhibitor on the O2/water interphase and a distributor of ions during the zinc deposition. The PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors show an excellent rate capability of 336, 292, 264, 232, 220, 195, 190, 175, and 165 F g\u22121 at a current density of 0.5, 1, 2, 5, 8, 10, 15, 20, 25, and 30 A g\u22121 (Fig. 5c and S11\u2020). The galvanostatic charge\u2013discharge curves and long cycling stability of the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors at a current density of 15 A g\u22121 are shown in Fig. 5d and e. The specific capacitance of the devices slightly increases at first due to activation, then remains quite stable, and ultimately gives a high retention of 100% of the initial specific capacitance after 6000 cycles. These results further demonstrate the excellent electrochemical performance of the Zn\u2013AC hybrid ion supercapacitors with the PAM/PVP layer. Notably, the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors have a high energy density of 118 W h\u22121 kg\u22121 and a power density of 17.9 kW kg\u22121 (based on the mass of AC materials, Fig. S12\u2020), where the energy density is superior to those of the bare Zn\u2013AC hybrid ion supercapacitors (Fig. S13 and Table S1\u2020).", "question": "What's the anode?", "answer": "zinc ", "answer_start": 934}
{"document_id": 75801, "context": "The electrochemical performance of the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors was tested by cyclic voltammetry and galvanostatic charge\u2013discharge tests within the voltage range of 0\u20132.0 V (Fig. 5). The CV curves of the hybrid ion capacitors at various scan rates from 10 mV s\u22121 to 200 mV s\u22121 maintain a quasi-rectangular shape, suggesting an EDLC-type behavior (Fig. 5a). Fig. 5b shows the voltage curves of the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors at various current densities from 0.5\u201330 A g\u22121. The symmetric and linear shape of the curves in the graph can be observed corresponding to the results of the CV test. At a current density of 1 A g\u22121, the bare Zn\u2013AC hybrid ion supercapacitors failed after 10 cycles, while the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors show a good cycling stability (Fig. S10\u2020). This superior stability can be attributed to the critical role of the PAM/PVP layer coated on the zinc anode acting as an inhibitor on the O2/water interphase and a distributor of ions during the zinc deposition. The PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors show an excellent rate capability of 336, 292, 264, 232, 220, 195, 190, 175, and 165 F g\u22121 at a current density of 0.5, 1, 2, 5, 8, 10, 15, 20, 25, and 30 A g\u22121 (Fig. 5c and S11\u2020). The galvanostatic charge\u2013discharge curves and long cycling stability of the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors at a current density of 15 A g\u22121 are shown in Fig. 5d and e. The specific capacitance of the devices slightly increases at first due to activation, then remains quite stable, and ultimately gives a high retention of 100% of the initial specific capacitance after 6000 cycles. These results further demonstrate the excellent electrochemical performance of the Zn\u2013AC hybrid ion supercapacitors with the PAM/PVP layer. Notably, the PAM/PVP-coated Zn\u2013AC hybrid ion supercapacitors have a high energy density of 118 W h\u22121 kg\u22121 and a power density of 17.9 kW kg\u22121 (based on the mass of AC materials, Fig. S12\u2020), where the energy density is superior to those of the bare Zn\u2013AC hybrid ion supercapacitors (Fig. S13 and Table S1\u2020).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75803, "context": "The intermediate LiPSs generated from charge/discharge processes can spontaneously dissolve into the electrolyte and freely migrate between the cathode and the anode through the separator, resulting in the loss of active materials, passivation of both the electrodes, and unavoidable self-discharge/recharge. So far two typical strategies covering physical confinement and chemical adsorption have been proven and generally accepted as an effective solution to address this issue. Physical confinement often relies on the high surface area or pore structure of the host materials, while chemical adsorption depends on the strong interaction between the host materials and LiPS species. Accordingly, rationally creating metal sulfides with a desired surface area, well-designed porosity, enhanced surface polar/selectivity, and tailored crystalline form has been achieved by a variety of approaches, e.g. solvothermal/hydrothermal methods, ball-milling technology, coprecipitation method, and innovative heat treatment technology.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75803, "context": "The intermediate LiPSs generated from charge/discharge processes can spontaneously dissolve into the electrolyte and freely migrate between the cathode and the anode through the separator, resulting in the loss of active materials, passivation of both the electrodes, and unavoidable self-discharge/recharge. So far two typical strategies covering physical confinement and chemical adsorption have been proven and generally accepted as an effective solution to address this issue. Physical confinement often relies on the high surface area or pore structure of the host materials, while chemical adsorption depends on the strong interaction between the host materials and LiPS species. Accordingly, rationally creating metal sulfides with a desired surface area, well-designed porosity, enhanced surface polar/selectivity, and tailored crystalline form has been achieved by a variety of approaches, e.g. solvothermal/hydrothermal methods, ball-milling technology, coprecipitation method, and innovative heat treatment technology.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75803, "context": "The intermediate LiPSs generated from charge/discharge processes can spontaneously dissolve into the electrolyte and freely migrate between the cathode and the anode through the separator, resulting in the loss of active materials, passivation of both the electrodes, and unavoidable self-discharge/recharge. So far two typical strategies covering physical confinement and chemical adsorption have been proven and generally accepted as an effective solution to address this issue. Physical confinement often relies on the high surface area or pore structure of the host materials, while chemical adsorption depends on the strong interaction between the host materials and LiPS species. Accordingly, rationally creating metal sulfides with a desired surface area, well-designed porosity, enhanced surface polar/selectivity, and tailored crystalline form has been achieved by a variety of approaches, e.g. solvothermal/hydrothermal methods, ball-milling technology, coprecipitation method, and innovative heat treatment technology.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75805, "context": "Bulk heterojunction (BHJ) polymer solar cells (PSCs) that convert absorbed sunlight into electrical energy have been in the spotlight due to their potential in large-scale and cost-effective roll-to-roll fabrication. In the past decade, massive endeavors concerning the development and interfacial engineering of novel light-harvesting materials have been made to improve the power conversion efficiency (PCE). Nowadays, the highest PCE exceeds 16% for single-junction BHJ PSCs. Interface layers, positioned between the photoactive layer and the anode/cathode electrode, play vital roles in governing the performance of PSCs. Interface layers are usually utilized to tailor the work function of the electrode for charge carrier collection maximization, modify the interface to alter the photoactive layer micromorphology, as well as minimize carrier recombination at the interfaces between the active layer and the transport layer. For a hole transport layer (HTL), pivotal parameters consist of high conductivity, high transparency, solution processability, favorable stability, etc. PEDOT:PSS, as the state-of-the-art hole transport material in organic optoelectronic devices, possesses outstanding edges of high transmittance in the visible spectrum and superior film-forming ability and thermal stability. However, PEDOT:PSS solution is strongly acidic and hygroscopic, which can etch the indium tin oxide (ITO) anode. Moreover, it has been verified that the spin-casted PEDOT:PSS thin film often exhibits inhomogeneous morphology and poor electrical conductivity, leading to poor efficiency and stability of devices. The development of a PEDOT:PSS HTL that possesses interconnected conductive domains and enhanced electrical conductivity is crucial to PSCs.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75805, "context": "Bulk heterojunction (BHJ) polymer solar cells (PSCs) that convert absorbed sunlight into electrical energy have been in the spotlight due to their potential in large-scale and cost-effective roll-to-roll fabrication. In the past decade, massive endeavors concerning the development and interfacial engineering of novel light-harvesting materials have been made to improve the power conversion efficiency (PCE). Nowadays, the highest PCE exceeds 16% for single-junction BHJ PSCs. Interface layers, positioned between the photoactive layer and the anode/cathode electrode, play vital roles in governing the performance of PSCs. Interface layers are usually utilized to tailor the work function of the electrode for charge carrier collection maximization, modify the interface to alter the photoactive layer micromorphology, as well as minimize carrier recombination at the interfaces between the active layer and the transport layer. For a hole transport layer (HTL), pivotal parameters consist of high conductivity, high transparency, solution processability, favorable stability, etc. PEDOT:PSS, as the state-of-the-art hole transport material in organic optoelectronic devices, possesses outstanding edges of high transmittance in the visible spectrum and superior film-forming ability and thermal stability. However, PEDOT:PSS solution is strongly acidic and hygroscopic, which can etch the indium tin oxide (ITO) anode. Moreover, it has been verified that the spin-casted PEDOT:PSS thin film often exhibits inhomogeneous morphology and poor electrical conductivity, leading to poor efficiency and stability of devices. The development of a PEDOT:PSS HTL that possesses interconnected conductive domains and enhanced electrical conductivity is crucial to PSCs.", "question": "What's the anode?", "answer": "indium tin oxide (ITO)", "answer_start": 1393}
{"document_id": 75805, "context": "Bulk heterojunction (BHJ) polymer solar cells (PSCs) that convert absorbed sunlight into electrical energy have been in the spotlight due to their potential in large-scale and cost-effective roll-to-roll fabrication. In the past decade, massive endeavors concerning the development and interfacial engineering of novel light-harvesting materials have been made to improve the power conversion efficiency (PCE). Nowadays, the highest PCE exceeds 16% for single-junction BHJ PSCs. Interface layers, positioned between the photoactive layer and the anode/cathode electrode, play vital roles in governing the performance of PSCs. Interface layers are usually utilized to tailor the work function of the electrode for charge carrier collection maximization, modify the interface to alter the photoactive layer micromorphology, as well as minimize carrier recombination at the interfaces between the active layer and the transport layer. For a hole transport layer (HTL), pivotal parameters consist of high conductivity, high transparency, solution processability, favorable stability, etc. PEDOT:PSS, as the state-of-the-art hole transport material in organic optoelectronic devices, possesses outstanding edges of high transmittance in the visible spectrum and superior film-forming ability and thermal stability. However, PEDOT:PSS solution is strongly acidic and hygroscopic, which can etch the indium tin oxide (ITO) anode. Moreover, it has been verified that the spin-casted PEDOT:PSS thin film often exhibits inhomogeneous morphology and poor electrical conductivity, leading to poor efficiency and stability of devices. The development of a PEDOT:PSS HTL that possesses interconnected conductive domains and enhanced electrical conductivity is crucial to PSCs.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75807, "context": "LiMn2O4 (LMO) was used as a cathode to evaluate the electrochemical performance of Al2O3-coated LTO in the WiSE (Fig. S5\u2020). The mass ratio of LMO:LTO was set as 2.5:1 to accommodate the low CE of LTO during the initial several cycles. 1C was used instead of a high rate to demonstrate the stability of the electrolyte in the full cell. Such LTO/LMO full cells delivered a voltage plateau at \u223c2.4 V during discharge. The discharging capacity based on LTO mass was 145 mA h g\u22121. In the first cycle, a coulombic efficiency (CE) of 84.5% was delivered, indicating that a relatively small amount of electrolyte was consumed to form an additional LiF-rich SEI on the Al2O3-coated LTO anode. In comparison, pairing the uncoated LTO and LMO delivered a CE of 50% (Fig. S6\u2020), further confirming the effect of the Al2O3 coating in suppressing the side reaction. As we reported previously, the reduction of salt anions bis(trifluoromethane sulfonyl)imide (TFSI) occurs between 1.9 V and 2.9 V. Although reduction of TFSI anions is expected to occur if an Al2O3 coating is absent (Fig. S7\u2020), formation of a complete SEI needs a long time (i.e., few cycles in galvanostatic charge/discharge cycles). The lithiation potential of pristine LTO resides beyond the cathodic limit of the WiSE, so a significant HER will occur before lithiation. The persistent evolution of gas undoubtedly prevents complete formation of the SEI. For the initial cycles, when a robust SEI has not been constructed, protection of the Al2O3 surface serves as a key barrier to ensure that SEI chemistry occurs, and that the SEI ingredient formed from the reduction of the TFSI anion adheres to the anode surface. After the most challenging period in the initial cycles, a dense and complete SEI will come into shape (Fig. S7\u2020), eventually providing long-term protection and allowing LTO to deliver a reversible capacity.", "question": "What's the cathode?", "answer": "LiMn2O4 (LMO)", "answer_start": 0}
{"document_id": 75807, "context": "LiMn2O4 (LMO) was used as a cathode to evaluate the electrochemical performance of Al2O3-coated LTO in the WiSE (Fig. S5\u2020). The mass ratio of LMO:LTO was set as 2.5:1 to accommodate the low CE of LTO during the initial several cycles. 1C was used instead of a high rate to demonstrate the stability of the electrolyte in the full cell. Such LTO/LMO full cells delivered a voltage plateau at \u223c2.4 V during discharge. The discharging capacity based on LTO mass was 145 mA h g\u22121. In the first cycle, a coulombic efficiency (CE) of 84.5% was delivered, indicating that a relatively small amount of electrolyte was consumed to form an additional LiF-rich SEI on the Al2O3-coated LTO anode. In comparison, pairing the uncoated LTO and LMO delivered a CE of 50% (Fig. S6\u2020), further confirming the effect of the Al2O3 coating in suppressing the side reaction. As we reported previously, the reduction of salt anions bis(trifluoromethane sulfonyl)imide (TFSI) occurs between 1.9 V and 2.9 V. Although reduction of TFSI anions is expected to occur if an Al2O3 coating is absent (Fig. S7\u2020), formation of a complete SEI needs a long time (i.e., few cycles in galvanostatic charge/discharge cycles). The lithiation potential of pristine LTO resides beyond the cathodic limit of the WiSE, so a significant HER will occur before lithiation. The persistent evolution of gas undoubtedly prevents complete formation of the SEI. For the initial cycles, when a robust SEI has not been constructed, protection of the Al2O3 surface serves as a key barrier to ensure that SEI chemistry occurs, and that the SEI ingredient formed from the reduction of the TFSI anion adheres to the anode surface. After the most challenging period in the initial cycles, a dense and complete SEI will come into shape (Fig. S7\u2020), eventually providing long-term protection and allowing LTO to deliver a reversible capacity.", "question": "What's the anode?", "answer": "Al2O3-coated LTO", "answer_start": 661}
{"document_id": 75807, "context": "LiMn2O4 (LMO) was used as a cathode to evaluate the electrochemical performance of Al2O3-coated LTO in the WiSE (Fig. S5\u2020). The mass ratio of LMO:LTO was set as 2.5:1 to accommodate the low CE of LTO during the initial several cycles. 1C was used instead of a high rate to demonstrate the stability of the electrolyte in the full cell. Such LTO/LMO full cells delivered a voltage plateau at \u223c2.4 V during discharge. The discharging capacity based on LTO mass was 145 mA h g\u22121. In the first cycle, a coulombic efficiency (CE) of 84.5% was delivered, indicating that a relatively small amount of electrolyte was consumed to form an additional LiF-rich SEI on the Al2O3-coated LTO anode. In comparison, pairing the uncoated LTO and LMO delivered a CE of 50% (Fig. S6\u2020), further confirming the effect of the Al2O3 coating in suppressing the side reaction. As we reported previously, the reduction of salt anions bis(trifluoromethane sulfonyl)imide (TFSI) occurs between 1.9 V and 2.9 V. Although reduction of TFSI anions is expected to occur if an Al2O3 coating is absent (Fig. S7\u2020), formation of a complete SEI needs a long time (i.e., few cycles in galvanostatic charge/discharge cycles). The lithiation potential of pristine LTO resides beyond the cathodic limit of the WiSE, so a significant HER will occur before lithiation. The persistent evolution of gas undoubtedly prevents complete formation of the SEI. For the initial cycles, when a robust SEI has not been constructed, protection of the Al2O3 surface serves as a key barrier to ensure that SEI chemistry occurs, and that the SEI ingredient formed from the reduction of the TFSI anion adheres to the anode surface. After the most challenging period in the initial cycles, a dense and complete SEI will come into shape (Fig. S7\u2020), eventually providing long-term protection and allowing LTO to deliver a reversible capacity.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75808, "context": "3Mg/Mg2Sn electrodes were subjected to galvanostatic C/D at various rates in Mg(HMDS)2/MgCl2. In addition to the unprecedented high capacity, the rate performance of 3Mg/Mg2Sn was also impressive. The stepwise increase in C/D rates resulted in a continuous decrease in reversible capacities, but the degree of reduction was not abrupt (Fig. 5A). For example, a reversible capacity of 805 mA h g\u22121 was delivered at 100 mA g\u22121 and as much as 87 and 53% (700 and 430 mA h g\u22121) of it was retained at 500 and 1500 mA g\u22121, respectively. Accordingly, the corresponding C/D profiles also showed a relatively small increase in overpotentials with an increase in the C/D rates (Fig. 5B). When compared with the plateau voltage at 100 mA g\u22121, the additional overpotential required at 1500 mA g\u22121 was only ca. \u00b150 mV. It should be stressed here that such excellence has never been reported for either alloy- or intercalation-type electrodes in MIBs. Most anode materials show a capacity of less than 400 mA h g\u22121 at a C/D rate lower than 100 mA g\u22121, which significantly decreases with increasing C/D rates (Table 1). A few materials can deliver reasonable capacities at high rates, but no performance has been comparable to that of 3Mg/Mg2Sn.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75808, "context": "3Mg/Mg2Sn electrodes were subjected to galvanostatic C/D at various rates in Mg(HMDS)2/MgCl2. In addition to the unprecedented high capacity, the rate performance of 3Mg/Mg2Sn was also impressive. The stepwise increase in C/D rates resulted in a continuous decrease in reversible capacities, but the degree of reduction was not abrupt (Fig. 5A). For example, a reversible capacity of 805 mA h g\u22121 was delivered at 100 mA g\u22121 and as much as 87 and 53% (700 and 430 mA h g\u22121) of it was retained at 500 and 1500 mA g\u22121, respectively. Accordingly, the corresponding C/D profiles also showed a relatively small increase in overpotentials with an increase in the C/D rates (Fig. 5B). When compared with the plateau voltage at 100 mA g\u22121, the additional overpotential required at 1500 mA g\u22121 was only ca. \u00b150 mV. It should be stressed here that such excellence has never been reported for either alloy- or intercalation-type electrodes in MIBs. Most anode materials show a capacity of less than 400 mA h g\u22121 at a C/D rate lower than 100 mA g\u22121, which significantly decreases with increasing C/D rates (Table 1). A few materials can deliver reasonable capacities at high rates, but no performance has been comparable to that of 3Mg/Mg2Sn.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75575, "context": "Electrochemical impedance spectroscopy (EIS) curves are presented in Fig. S8.\u2020 A larger slope, which is associated with the Warburg impedance (Ws), was observed in the low-frequency region of the curve of the Fe-intercalated ML Ti3C2Tx electrode. Such an occurrence is related to the migration of electrolyte ions within the electrode. It is inferred that the faster kinetics of EMIm+ were derived from the increased space caused by Fe pre-intercalation. Ex situ Ti 2p and Fe 2p XPS spectra are presented in Fig. S9;\u2020 no obvious shifts were observed. This finding indicates that the charge storage mechanism of the Fe pre-intercalated ML Ti3C2Tx anode is based on the intercalation/de-intercalation behavior of EMIm+ instead of a redox process. Therefore, the larger real interlayer space contributed to the enhanced electrochemical performance. The scheme in Fig. 5d shows the charge storage mechanism of this DIB. Upon charging, EMIm+ cations were inserted into Fe pre-intercalated ML Ti3C2Tx, whereas PF6\u2212 anions were intercalated into the graphite cathode. Charge\u2013discharge profiles of the full DIB are presented in Fig. S10\u2020. The DIB provided an energy density of 76 W h kg\u22121 at a power density of 360 W kg\u22121. The cycling stabilities and capacity retentions of the electrodes were examined via performing GCD tests at the same current density. After 50 cycles, the DIB retained 94% of its initial capacity (Fig. 5e), indicating its improved stability compared with a DIB using the ML Ti3C2Tx anode (71%). Ragone plots are presented in the inset of Fig. 5e. The full DIB displayed a good rate capacity, with energy densities of 76, 70, and 64 W h kg\u22121 at power densities of 360, 900, and 1800 W kg\u22121, respectively. However, when the power density was higher than 3600 W kg\u22121, the energy density was reduced. The dual-ion intercalation mechanism of this DIB provides a new route for multi-ion storage.", "question": "What's the cathode?", "answer": "graphite ", "answer_start": 1043}
{"document_id": 75575, "context": "Electrochemical impedance spectroscopy (EIS) curves are presented in Fig. S8.\u2020 A larger slope, which is associated with the Warburg impedance (Ws), was observed in the low-frequency region of the curve of the Fe-intercalated ML Ti3C2Tx electrode. Such an occurrence is related to the migration of electrolyte ions within the electrode. It is inferred that the faster kinetics of EMIm+ were derived from the increased space caused by Fe pre-intercalation. Ex situ Ti 2p and Fe 2p XPS spectra are presented in Fig. S9;\u2020 no obvious shifts were observed. This finding indicates that the charge storage mechanism of the Fe pre-intercalated ML Ti3C2Tx anode is based on the intercalation/de-intercalation behavior of EMIm+ instead of a redox process. Therefore, the larger real interlayer space contributed to the enhanced electrochemical performance. The scheme in Fig. 5d shows the charge storage mechanism of this DIB. Upon charging, EMIm+ cations were inserted into Fe pre-intercalated ML Ti3C2Tx, whereas PF6\u2212 anions were intercalated into the graphite cathode. Charge\u2013discharge profiles of the full DIB are presented in Fig. S10\u2020. The DIB provided an energy density of 76 W h kg\u22121 at a power density of 360 W kg\u22121. The cycling stabilities and capacity retentions of the electrodes were examined via performing GCD tests at the same current density. After 50 cycles, the DIB retained 94% of its initial capacity (Fig. 5e), indicating its improved stability compared with a DIB using the ML Ti3C2Tx anode (71%). Ragone plots are presented in the inset of Fig. 5e. The full DIB displayed a good rate capacity, with energy densities of 76, 70, and 64 W h kg\u22121 at power densities of 360, 900, and 1800 W kg\u22121, respectively. However, when the power density was higher than 3600 W kg\u22121, the energy density was reduced. The dual-ion intercalation mechanism of this DIB provides a new route for multi-ion storage.", "question": "What's the anode?", "answer": "ML Ti3C2Tx", "answer_start": 635}
{"document_id": 75575, "context": "Electrochemical impedance spectroscopy (EIS) curves are presented in Fig. S8.\u2020 A larger slope, which is associated with the Warburg impedance (Ws), was observed in the low-frequency region of the curve of the Fe-intercalated ML Ti3C2Tx electrode. Such an occurrence is related to the migration of electrolyte ions within the electrode. It is inferred that the faster kinetics of EMIm+ were derived from the increased space caused by Fe pre-intercalation. Ex situ Ti 2p and Fe 2p XPS spectra are presented in Fig. S9;\u2020 no obvious shifts were observed. This finding indicates that the charge storage mechanism of the Fe pre-intercalated ML Ti3C2Tx anode is based on the intercalation/de-intercalation behavior of EMIm+ instead of a redox process. Therefore, the larger real interlayer space contributed to the enhanced electrochemical performance. The scheme in Fig. 5d shows the charge storage mechanism of this DIB. Upon charging, EMIm+ cations were inserted into Fe pre-intercalated ML Ti3C2Tx, whereas PF6\u2212 anions were intercalated into the graphite cathode. Charge\u2013discharge profiles of the full DIB are presented in Fig. S10\u2020. The DIB provided an energy density of 76 W h kg\u22121 at a power density of 360 W kg\u22121. The cycling stabilities and capacity retentions of the electrodes were examined via performing GCD tests at the same current density. After 50 cycles, the DIB retained 94% of its initial capacity (Fig. 5e), indicating its improved stability compared with a DIB using the ML Ti3C2Tx anode (71%). Ragone plots are presented in the inset of Fig. 5e. The full DIB displayed a good rate capacity, with energy densities of 76, 70, and 64 W h kg\u22121 at power densities of 360, 900, and 1800 W kg\u22121, respectively. However, when the power density was higher than 3600 W kg\u22121, the energy density was reduced. The dual-ion intercalation mechanism of this DIB provides a new route for multi-ion storage.", "question": "What's the anode?", "answer": "ML Ti3C2Tx", "answer_start": 1486}
{"document_id": 75576, "context": "From the linear relationship of Ip and \u03bd0.5 (Fig. S13\u2020), (cathodic peak at 2.3 V), (cathodic peak at 1.9 V), and (anodic peak at 2.4 V) were obtained. The DLi+ values of the Co5.47Nx/S cathode were 219.9, 14.8, and 31.5 \u00d7 10\u221215 cm2 s\u22121 for peak A, B, and C, respectively. Importantly, the DLi+ of peak A of Co5.47Nx/S was up to four fold that of the Co5.47N/S cathode (48.6, 18.1, and 18.1 \u00d7 10\u221215 cm2 s\u22121 for peak A, B, and C, respectively), as plotted in Fig. 6d. The adsorption efficacy of cobalt nitride is attributed to its strong chemical interaction with LiPSs through both Co\u2013S and N\u2013Li bonds. The strong Li\u2013N bonding in Co5.47N without nitrogen vacancies impedes direct electron transfer to the LiPSs and delays Li+ diffusion, resulting in sluggish reaction kinetics. Compared with Co5.47N, Co5.47Nx with nitrogen vacancies has a lower N content, which leads to decreased N\u2013Li bonding and accelerated Li+ transportation. The cycling stability of Co5.47Nx and Co5.47N was evaluated at a current density of 0.5C, and the results are shown in Fig. S14.\u2020 After 200 cycles, the Co5.47Nx electrode showed a capacity retention of 85%, which was higher than the 76% for the Co5.47N electrode without nitrogen vacancies. These results suggest that Co5.47Nx facilitates Li+ transportation through its hierarchical structure and nitrogen vacancies, resulting in promising cycling and rate capacity.", "question": "What's the cathode?", "answer": " Co5.47Nx/S ", "answer_start": 173}
{"document_id": 75576, "context": "From the linear relationship of Ip and \u03bd0.5 (Fig. S13\u2020), (cathodic peak at 2.3 V), (cathodic peak at 1.9 V), and (anodic peak at 2.4 V) were obtained. The DLi+ values of the Co5.47Nx/S cathode were 219.9, 14.8, and 31.5 \u00d7 10\u221215 cm2 s\u22121 for peak A, B, and C, respectively. Importantly, the DLi+ of peak A of Co5.47Nx/S was up to four fold that of the Co5.47N/S cathode (48.6, 18.1, and 18.1 \u00d7 10\u221215 cm2 s\u22121 for peak A, B, and C, respectively), as plotted in Fig. 6d. The adsorption efficacy of cobalt nitride is attributed to its strong chemical interaction with LiPSs through both Co\u2013S and N\u2013Li bonds. The strong Li\u2013N bonding in Co5.47N without nitrogen vacancies impedes direct electron transfer to the LiPSs and delays Li+ diffusion, resulting in sluggish reaction kinetics. Compared with Co5.47N, Co5.47Nx with nitrogen vacancies has a lower N content, which leads to decreased N\u2013Li bonding and accelerated Li+ transportation. The cycling stability of Co5.47Nx and Co5.47N was evaluated at a current density of 0.5C, and the results are shown in Fig. S14.\u2020 After 200 cycles, the Co5.47Nx electrode showed a capacity retention of 85%, which was higher than the 76% for the Co5.47N electrode without nitrogen vacancies. These results suggest that Co5.47Nx facilitates Li+ transportation through its hierarchical structure and nitrogen vacancies, resulting in promising cycling and rate capacity.", "question": "What's the cathode?", "answer": "Co5.47N/S ", "answer_start": 350}
{"document_id": 75580, "context": "In this work, a mechanism is proposed to explain the phenomenon of columnar lithium metal deposition. An electrolyte additive, such as HF, is selectively reduced at high potential vs. Li/Li+ to form uniformly distributed crystalline LiF particles with preferred crystallographic texture which are then encased in an amorphous matrix of solvent reduction products, as evidenced by systematic electrochemical analysis and in situ X-ray surface scattering. The LiF quantity and distribution are directly tunable by choosing an appropriate additive concentration and electrochemical cycling rate. Interfaces between LiF and the amorphous phase act as fast lithium-ion diffusion pathways, promoting a thin and more uniform SEI which leads to a very high lithium metal nucleation density relative to additive-free systems followed by nearly-isotropic and eventually vertical columnar growth, observed in real-time using operando small angle X-ray scattering. Understanding this process step-by-step provides new insights into the role of electrolyte additives and provides new information for the rational design of such additives. As HF is damaging to cathodes, current collectors, and other cell components, new additives which decompose at high potentials vs. lithium and direct the formation of a columnar morphology should be developed for practical use in lithium metal batteries.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75721, "context": "To summarize, multiple organic-based active materials showed promising characteristics in potassium-based batteries. Their capacities and potentials are typically less attractive than those of the state-of-the-art inorganic analogs, but the demonstrated rate and cycle capabilities make them highly competitive. There are still plenty of opportunities to improve the characteristics of the organic-based compounds using the truly unlimited diversity of molecular structures and tunability of their properties via functional group substitution. New advanced cathode and anode materials can be developed via rational molecular design, morphology optimization, engineering conductive fillers, and tuning the electrolyte composition.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75721, "context": "To summarize, multiple organic-based active materials showed promising characteristics in potassium-based batteries. Their capacities and potentials are typically less attractive than those of the state-of-the-art inorganic analogs, but the demonstrated rate and cycle capabilities make them highly competitive. There are still plenty of opportunities to improve the characteristics of the organic-based compounds using the truly unlimited diversity of molecular structures and tunability of their properties via functional group substitution. New advanced cathode and anode materials can be developed via rational molecular design, morphology optimization, engineering conductive fillers, and tuning the electrolyte composition.", "question": "What's the anode?", "answer": "", "answer_start": 0}
{"document_id": 75721, "context": "To summarize, multiple organic-based active materials showed promising characteristics in potassium-based batteries. Their capacities and potentials are typically less attractive than those of the state-of-the-art inorganic analogs, but the demonstrated rate and cycle capabilities make them highly competitive. There are still plenty of opportunities to improve the characteristics of the organic-based compounds using the truly unlimited diversity of molecular structures and tunability of their properties via functional group substitution. New advanced cathode and anode materials can be developed via rational molecular design, morphology optimization, engineering conductive fillers, and tuning the electrolyte composition.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75662, "context": "After structural comparison, the activity of oxygen and manganese was further probed to reveal the charge compensation in electrochemistry. Operando DEMS was performed to monitor the released anionic species during the charging process. The operando DEMS data was collected with active material loading of around 8 mg (Fig. 3). In the initial charge process for typical LMO, carbon dioxide gas was evolved at the beginning, accompanied by a large amount of oxygen gas release with maximum carbon dioxide evolution. The total gas evolution was summed to be 59.3 mmol CO2 per mol of active material and 70.2 mmol O2 per mol of active material. The CO2 gas may result from the electrolyte decomposition, the reaction between the electrolyte and O2, and impurity Li2CO3 decomposition. In contrast, the T-LMO electrode delivered a minimal amount of carbon dioxide and oxygen gas release. The cumulative CO2 and O2 detected from T-LMO during the initial charge process was 10.5 mmol and 9.1 mmol per mol of active material, respectively. The reduced gas release in the treated sample indicates the improved electrochemical stability of the T-LMO material when operating at high voltage in the battery. The different outgassing behaviors of LMO and T-LMO under identical cycling conditions imply that the two materials have different oxygen activities.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75663, "context": "The normalized voltage characteristics for the 1st and 2nd cycles at C/20 (standard CC protocol) for Li[Li0.2Mn0.6Ni0.1Co0.1]O2 are presented in Fig. 2. During the 1st charge, we observed a rapid increase of the potential up to 4.4 V followed by a pseudo-plateau, while during the 1st discharge, the potential declines down to 3.5 V and a subsequent long pseudo-plateau was registered. The observed substantial hysteresis between charge and discharge potentials suggests: (i) sluggish kinetics of the occurring process and (ii) structural reorganization taking place. Comparing the 1st and 2nd cycles, we noticed that the 2nd charge characteristics do not show a large pseudo-plateau between 4.4 and 4.8 V but rather a monotonic S-type shape. Interestingly the potential of the 2nd discharge curve is slightly higher than that of the 1st discharge. In turn, the lower potential for the 2nd charge characteristics (in relation to the 1st one) leads to much lower hysteresis for the 2nd cycle compared with that for the initial one. This transition from stair-case to S-type potential characteristics between the 1st and 2nd cycles is commonly observed for other Li-rich NMC compounds; however the exact mechanism is still elusive and will be investigated further in this study. Comparing the discharge capacities at various current densities (Fig. 3a), the significant discharge capacity fade from approximately 350 to 290 mA h g\u22121 during the first two cycles is observed. Furthermore, the specific charge only slightly responds to the increase of the current loads and each rate increase (C/20, C/10, C/5, C/2, and 1C) is followed by a minor decrease of the practical specific charge until reaching 150 mA h g\u22121 at a 1C rate. Going back to the C/20 rate leads to an increase of the discharge capacity slightly below 250 mA h g\u22121. A similar observation was made in other reports within the literature where the first discharge capacity is above 300 mA h g\u22121 and after a few cycles it drops to ca. 250 mA h g\u22121 comparable to that in our paper. We suspect that most probably the anomalously high discharge capacity is due to the nanosize of primary particles which have a very high total surface area and as such enhance the electrolyte decomposition, increasing the observed specific charge. It is also worth noticing that after rate capability tests, during the second cyclic tests at C/20 the material works with a reversible capacity of 250 mA h g\u22121, suggesting most probably that the observed very high initial discharge capacity is due to the parasitic reactions. Voltage profiles for the second cycles registered at various current loads are shown in Fig. 3b and exhibit almost the same S-type character, confirming that reorganization taking place between the 1st and 2nd cycles persists in the following tests.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75664, "context": "The electrochemical performance of LTO electrodes coated with various materials was evaluated by linear sweep voltammetry (Fig. 3). Hydrogen evolution began at \u223c1.8 V vs. Li on the pristine LTO surface, which was higher than its lithiation potential (1.55 V). The HER process (rather than lithiation of LTO) dominated the cathodic reaction during the scan. The carbon coating enhanced the electronic conductivity of LTO, thus accelerating the HER (as evidenced by the higher currents and positively shifted HER potential). The TiO2 coating also positively shifted the cathodic limit due to its high catalytic activity. In contrast, the ZnO coating and Al2O3 costing negatively shifted the cathodic limit potential by 0.1 V. In addition, the HER currents on the ZnO-coated and Al2O3-coated LTO electrode were much lower compared with those on pristine LTO. The capability of HER suppression as quantified by the onset potential of the HER should increase in the order TiO2 < carbon < LTO < ZnO < Al2O3, which was consistent with the prediction in Fig. 1. The Al2O3 coating not only suppressed the HER catalytic activity but also acted as a kinetic barrier to slow down electron transfer from the electrode bulk to protons in the electrolyte. Al2O3 coating shifted the HER potential to <1.5 V, so Li+ intercalation was enabled before the HER, as evidenced by a sharp lithiation peak at 1.55 V (Fig. 4a). Using a similar approach, we also evaluated the effect of surface coating on the oxygen evolution reaction (OER). Al2O3 coating and TiO2 coating on LiNi0.5Mn1.5O4 reduced the side reactions on this high-voltage (4.8 V) cathode material only slightly (Fig. S3\u2020).", "question": "What's the cathode?", "answer": "LiNi0.5Mn1.5O4", "answer_start": 1550}
{"document_id": 75664, "context": "The electrochemical performance of LTO electrodes coated with various materials was evaluated by linear sweep voltammetry (Fig. 3). Hydrogen evolution began at \u223c1.8 V vs. Li on the pristine LTO surface, which was higher than its lithiation potential (1.55 V). The HER process (rather than lithiation of LTO) dominated the cathodic reaction during the scan. The carbon coating enhanced the electronic conductivity of LTO, thus accelerating the HER (as evidenced by the higher currents and positively shifted HER potential). The TiO2 coating also positively shifted the cathodic limit due to its high catalytic activity. In contrast, the ZnO coating and Al2O3 costing negatively shifted the cathodic limit potential by 0.1 V. In addition, the HER currents on the ZnO-coated and Al2O3-coated LTO electrode were much lower compared with those on pristine LTO. The capability of HER suppression as quantified by the onset potential of the HER should increase in the order TiO2 < carbon < LTO < ZnO < Al2O3, which was consistent with the prediction in Fig. 1. The Al2O3 coating not only suppressed the HER catalytic activity but also acted as a kinetic barrier to slow down electron transfer from the electrode bulk to protons in the electrolyte. Al2O3 coating shifted the HER potential to <1.5 V, so Li+ intercalation was enabled before the HER, as evidenced by a sharp lithiation peak at 1.55 V (Fig. 4a). Using a similar approach, we also evaluated the effect of surface coating on the oxygen evolution reaction (OER). Al2O3 coating and TiO2 coating on LiNi0.5Mn1.5O4 reduced the side reactions on this high-voltage (4.8 V) cathode material only slightly (Fig. S3\u2020).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75666, "context": "As ideal self-template precursor, metal\u2013organic frameworks (MOFs) with regular compositions can be converted into porosity-tunable materials with a uniform distribution of metal-based components and carbon. The nano-sized metal-based components sustaining the framework of MOFs are able to curtail the distance of ion diffusion and create more electrolyte-accessible sites. Porous carbon, derived from decomposition of the organic linkers, can efficiently alleviate the volume variation of the metal-based components during the ion insertion/extraction process, and it can also reinforce electron transmission. In addition, the incorporation of heteroatoms can be easily realized by the modification of organic linkers in MOFs. Recently, some studies have reported that MOF-derived nanocomposites are promising anode materials for LIHCs and SIHCs, and they can facilitate boosting the pseudocapacitive-dominant charge storage as well as maintain the structure stability.", "question": "What's the anode?", "answer": "MOF-derived nanocomposites", "answer_start": 770}
{"document_id": 75666, "context": "As ideal self-template precursor, metal\u2013organic frameworks (MOFs) with regular compositions can be converted into porosity-tunable materials with a uniform distribution of metal-based components and carbon. The nano-sized metal-based components sustaining the framework of MOFs are able to curtail the distance of ion diffusion and create more electrolyte-accessible sites. Porous carbon, derived from decomposition of the organic linkers, can efficiently alleviate the volume variation of the metal-based components during the ion insertion/extraction process, and it can also reinforce electron transmission. In addition, the incorporation of heteroatoms can be easily realized by the modification of organic linkers in MOFs. Recently, some studies have reported that MOF-derived nanocomposites are promising anode materials for LIHCs and SIHCs, and they can facilitate boosting the pseudocapacitive-dominant charge storage as well as maintain the structure stability.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75665, "context": "Based on the above discussion, a driving mechanism of the EC procedures in the shoulder-by-shoulder structure was proposed (Fig. 2d) which is similar to that of a planar-arrangement supercapacitor. When both WO3 films were transparent during the first process, in essence, the conductive ITO layers were likely acting as two split capacitance plates. Once a working voltage was applied, Li ions were driven by the edge effect of the electric field of the capacitance plates and intercalated into the WO3 film at the negative potential, namely PI. Because the edge effect of the electric field was intense in the middle of the two EC films, more Li ions were injected into this area than into other areas, showing an uneven color distribution. These concentration differences resulted in the self-diffusion of Li ions in the colored film, namely PIII. However, when one EC unit was colored in the subsequent processes, it was likely acting as a charged capacitor. Once a reverse driving voltage was employed, the charge transfer procedure (namely PII) preferentially occurred. Electrons were transferred through the outer loop, while Li ions were transferred through the electrolyte, and they simultaneously intercalated into another EC film that was at a negative potential and colored it. The ions (electrons and Li ions) in the area of the colored film that was next to the middle of the two EC units were first transported into its counterpart and placed in the area that was also next to the seam because the electric field in the seam area was very intense. It is reasonable that PII is much quicker than PI because discharging a capacitor is a rapid process. When PII finished, the EC film was partly colored. Next, PI and PIII both occurred, and the partly colored film became completely colored. When the working voltage was turned off, the colored film became evenly colored, driven by PIII.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75667, "context": "To confirm the improved energy density, a hybrid supercapacitor was fabricated based on a solid-state 400-KOH-Ti3C2 anode and an active catholyte containing Mn2+ in 2 M H2SO4 electrolyte. Before assembling the hybrid supercapacitor, the CF as a current collector was pretreated by electrochemical predeposition with 3 mA h cm\u22122 MnO2 on the surface. The electrochemical performance of the as-assembled hybrid device was systematically investigated to demonstrate its unique advantages. As shown in Fig. 4a, in situ potential detection was performed, in which the Ag/AgCl reference electrode was introduced into the two-electrode system to explore in situ the potential variation of the respective electrode. This hybrid supercapacitor achieves a wide voltage window up to 1.7 V (red line), benefiting from the potential difference between the solid 400-KOH-Ti3C2 anode (dark cyan line) and active catholyte containing Mn2+ (black line). It is worth mentioning that such a wide operating voltage window is superior to that of most recently reported hybrid supercapacitors (see Table S2\u2020) and even comparable to that of the \u201cwater in salt\u201d electrolyte-based hybrid capacitors.Fig. 4b displays the CV curves of the hybrid supercapacitor at various scan rates. All the CV curves exhibit an approximate rectangular shape, which suggests that the operation mechanism in this hybrid device is bonding/debonding-induced pseudocapacitance in nature. Additionally, it is found that the addition of Mn2+ does not significantly affect the reaction kinetics of the 400-KOH-Ti3C2 anode (see Fig. S16\u2020 and the corresponding discussions). On the other hand, the near linear symmetric triangular charge/discharge curves at various current densities also confirm the pseudocapacitance characteristics of the hybrid device (Fig. 4c), which agrees well with the CV results. The corresponding specific capacitance was calculated based on the charge\u2013discharge curves (see detailed calculations in the ESI\u2020). Impressively, the hybrid device delivers an appreciable specific capacitance of 312.8 F g\u22121 at 1 A g\u22121 and 131.2 F g\u22121 at 80 A g\u22121, showing good rate performance (Fig. S17\u2020). The energy and power densities of the present hybrid supercapacitor were also calculated on the basis of the total mass of 400-KOH-Ti3C2 and consumed MnO2, which is given as a Ragone plot profile (Fig. 4d). As displayed in Fig. 4d, the hybrid supercapacitor exhibits a maximum energy density of 43.4 W h kg\u22121 at a power density of 488.7 W kg\u22121. Even at a high power density of 40 kW kg\u22121, the energy density still remains 18.2 W h kg\u22121. It is worth noting that the energy density achieved here is markedly superior to those of most recently reported hybrid supercapacitors, as listed in Table S3.\u2020 These facts indicate that benefiting from both the high operating voltage and specific capacity of the active catholyte containing Mn2+, the energy density of the hybrid supercapacitor is significantly enhanced. In addition, this hybrid supercapacitor exhibits prominent cycling stability with a high-capacitance retention of 75% over 20000 cycles at 4 A g\u22121 (Fig. 4e). The charge/discharge curves at different cycles are shown in Fig. S18\u2020 to illustrate the high coulombic efficiency of the hybrid supercapacitor.", "question": "What's the anode?", "answer": "400-KOH-Ti3C2", "answer_start": 102}
{"document_id": 75667, "context": "To confirm the improved energy density, a hybrid supercapacitor was fabricated based on a solid-state 400-KOH-Ti3C2 anode and an active catholyte containing Mn2+ in 2 M H2SO4 electrolyte. Before assembling the hybrid supercapacitor, the CF as a current collector was pretreated by electrochemical predeposition with 3 mA h cm\u22122 MnO2 on the surface. The electrochemical performance of the as-assembled hybrid device was systematically investigated to demonstrate its unique advantages. As shown in Fig. 4a, in situ potential detection was performed, in which the Ag/AgCl reference electrode was introduced into the two-electrode system to explore in situ the potential variation of the respective electrode. This hybrid supercapacitor achieves a wide voltage window up to 1.7 V (red line), benefiting from the potential difference between the solid 400-KOH-Ti3C2 anode (dark cyan line) and active catholyte containing Mn2+ (black line). It is worth mentioning that such a wide operating voltage window is superior to that of most recently reported hybrid supercapacitors (see Table S2\u2020) and even comparable to that of the \u201cwater in salt\u201d electrolyte-based hybrid capacitors.Fig. 4b displays the CV curves of the hybrid supercapacitor at various scan rates. All the CV curves exhibit an approximate rectangular shape, which suggests that the operation mechanism in this hybrid device is bonding/debonding-induced pseudocapacitance in nature. Additionally, it is found that the addition of Mn2+ does not significantly affect the reaction kinetics of the 400-KOH-Ti3C2 anode (see Fig. S16\u2020 and the corresponding discussions). On the other hand, the near linear symmetric triangular charge/discharge curves at various current densities also confirm the pseudocapacitance characteristics of the hybrid device (Fig. 4c), which agrees well with the CV results. The corresponding specific capacitance was calculated based on the charge\u2013discharge curves (see detailed calculations in the ESI\u2020). Impressively, the hybrid device delivers an appreciable specific capacitance of 312.8 F g\u22121 at 1 A g\u22121 and 131.2 F g\u22121 at 80 A g\u22121, showing good rate performance (Fig. S17\u2020). The energy and power densities of the present hybrid supercapacitor were also calculated on the basis of the total mass of 400-KOH-Ti3C2 and consumed MnO2, which is given as a Ragone plot profile (Fig. 4d). As displayed in Fig. 4d, the hybrid supercapacitor exhibits a maximum energy density of 43.4 W h kg\u22121 at a power density of 488.7 W kg\u22121. Even at a high power density of 40 kW kg\u22121, the energy density still remains 18.2 W h kg\u22121. It is worth noting that the energy density achieved here is markedly superior to those of most recently reported hybrid supercapacitors, as listed in Table S3.\u2020 These facts indicate that benefiting from both the high operating voltage and specific capacity of the active catholyte containing Mn2+, the energy density of the hybrid supercapacitor is significantly enhanced. In addition, this hybrid supercapacitor exhibits prominent cycling stability with a high-capacitance retention of 75% over 20000 cycles at 4 A g\u22121 (Fig. 4e). The charge/discharge curves at different cycles are shown in Fig. S18\u2020 to illustrate the high coulombic efficiency of the hybrid supercapacitor.", "question": "What's the electrolyte?", "answer": "Mn2+ in 2 M H2SO4", "answer_start": 157}
{"document_id": 75667, "context": "To confirm the improved energy density, a hybrid supercapacitor was fabricated based on a solid-state 400-KOH-Ti3C2 anode and an active catholyte containing Mn2+ in 2 M H2SO4 electrolyte. Before assembling the hybrid supercapacitor, the CF as a current collector was pretreated by electrochemical predeposition with 3 mA h cm\u22122 MnO2 on the surface. The electrochemical performance of the as-assembled hybrid device was systematically investigated to demonstrate its unique advantages. As shown in Fig. 4a, in situ potential detection was performed, in which the Ag/AgCl reference electrode was introduced into the two-electrode system to explore in situ the potential variation of the respective electrode. This hybrid supercapacitor achieves a wide voltage window up to 1.7 V (red line), benefiting from the potential difference between the solid 400-KOH-Ti3C2 anode (dark cyan line) and active catholyte containing Mn2+ (black line). It is worth mentioning that such a wide operating voltage window is superior to that of most recently reported hybrid supercapacitors (see Table S2\u2020) and even comparable to that of the \u201cwater in salt\u201d electrolyte-based hybrid capacitors.Fig. 4b displays the CV curves of the hybrid supercapacitor at various scan rates. All the CV curves exhibit an approximate rectangular shape, which suggests that the operation mechanism in this hybrid device is bonding/debonding-induced pseudocapacitance in nature. Additionally, it is found that the addition of Mn2+ does not significantly affect the reaction kinetics of the 400-KOH-Ti3C2 anode (see Fig. S16\u2020 and the corresponding discussions). On the other hand, the near linear symmetric triangular charge/discharge curves at various current densities also confirm the pseudocapacitance characteristics of the hybrid device (Fig. 4c), which agrees well with the CV results. The corresponding specific capacitance was calculated based on the charge\u2013discharge curves (see detailed calculations in the ESI\u2020). Impressively, the hybrid device delivers an appreciable specific capacitance of 312.8 F g\u22121 at 1 A g\u22121 and 131.2 F g\u22121 at 80 A g\u22121, showing good rate performance (Fig. S17\u2020). The energy and power densities of the present hybrid supercapacitor were also calculated on the basis of the total mass of 400-KOH-Ti3C2 and consumed MnO2, which is given as a Ragone plot profile (Fig. 4d). As displayed in Fig. 4d, the hybrid supercapacitor exhibits a maximum energy density of 43.4 W h kg\u22121 at a power density of 488.7 W kg\u22121. Even at a high power density of 40 kW kg\u22121, the energy density still remains 18.2 W h kg\u22121. It is worth noting that the energy density achieved here is markedly superior to those of most recently reported hybrid supercapacitors, as listed in Table S3.\u2020 These facts indicate that benefiting from both the high operating voltage and specific capacity of the active catholyte containing Mn2+, the energy density of the hybrid supercapacitor is significantly enhanced. In addition, this hybrid supercapacitor exhibits prominent cycling stability with a high-capacitance retention of 75% over 20000 cycles at 4 A g\u22121 (Fig. 4e). The charge/discharge curves at different cycles are shown in Fig. S18\u2020 to illustrate the high coulombic efficiency of the hybrid supercapacitor.", "question": "What's the anode?", "answer": " 400-KOH-Ti3C2", "answer_start": 847}
{"document_id": 75707, "context": "As seen from the surface morphology images of these three electrodes (Fig. 2 and S5\u2020), they have their own characteristics and are all totally different from the original IF (Fig. S6\u2020). As shown in Fig. 2a, there are abundant FeCO3 cubes (8\u201315 \u03bcm in edge length) on the surface of the FeCO3@IF electrode. The TEM images (Fig. 2b) show that the width of the crystal lattice is about 0.278 nm, matching the (104) face of FeCO3, which confirms the formation of FeCO3 and coincides with the results in the XRD patterns and XPS spectra. According to the SEM images in Fig. 2a, S5a and b,\u2020 the FeCO3 cubes do not completely cover the surface of the IF. As shown in Fig. 2c, the surface of the area without FeCO3 cubes is rough and is clearly different from the smooth surface of IF (Fig. S6\u2020). According to the distribution of elements (C, O and Fe) in the area without FeCO3 cubes, C, O and Fe are uniformly distributed (Fig. S7b\u2013d\u2020). The EDS data (Fig. S7e\u2020) confirm that the C, O and Fe content (wt%) is 8.63%, 35.58% and 55.79%, respectively. Therefore, the atomic ratio of C, O and Fe is 1.00:3.09:1.38, which is close to the atomic ratio of FeCO3. The slightly high iron content may be due to the iron foam substrate. These results confirm that the area without FeCO3 cubes is also covered by FeCO3 compounds. In addition, the TEM results in Fig. 2 further show that aside from the FeCO3 cubes with high crystallinity according to their long-range ordered crystal structure (Fig. 2b), some compounds with short-range ordered and long-range disordered crystal structures are also observed (Fig. 2d). The widths of the crystal lattices are about 0.278 nm and 0.234 nm, which match the (104) and (110) faces of FeCO3, respectively. Therefore, the compounds on the surface of IF without FeCO3 cubes are mainly FeCO3 but with low crystallinity according to the EDS and TEM results. Unlike FeCO3@IF, Fe3O4@IF is covered with tightly packed Fe3O4 nanoparticles (Fig. 2c, S5c and d\u2020). The morphology of Fe\u2013O\u2013M@IF is similar to that of FeCO3@IF, but many long and interlaced nanowires are distributed around the cubes. Moreover, the edge length of the cubes is 2\u20133 times that of FeCO3@IF, and the surface is uneven. Compared with the original IF with its smooth surface, the increase in roughness can improve the specific surface area (Fig. S8 and Table S2\u2020) and promote the penetration of the electrolyte as well as mass transfer. Based on the above characterizations, three different 3D iron-based electrodes have been successfully prepared via changing the iron source.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75710, "context": "Herein, we fabricated two artificial SEIs on Na metal anodes via similar chemical replacement reactions between Na metal and SnCl4 liquid or SnCl2 additive dissolved in diethylene glycol dimethyl ether (DGM). According to X-ray photoelectron spectroscopy (XPS) depth-profiling results, the SnCl4 liquid treatment leads to a uniform and high ionic diffusion artificial SEI consisting of a simultaneously generated Na\u2013Sn alloy and NaCl, whereas the SnCl2 additive results in a disordered and heterogeneous artificial SEI (Na\u2013Sn alloy, NaCl, Sn metal, organo-chloride, ROCO2Na and RCH2ONa) due to the heterogeneous reaction between the Na metal anode and SnCl2/DGM solvent. It is found that the cycling performance of the SnCl4\u2013Na electrodes is highly superior to that of the SnCl2\u2013Na electrodes, which is mainly ascribed to the uniformity and ionic diffusion distinction of the two artificial SEIs. The importance of homogeneous and high ionic diffusion properties for the artificial SEI is also demonstrated by simulation results. Overall, the artificial SEI of SnCl4\u2013Na electrodes can afford three key advantages: (i) the simple and controllable fabrication leads to a homogeneous artificial SEI consisting of uniformly distributed Na\u2013Sn alloy and NaCl, avoiding the non-uniform products caused by the side reactions that commonly exist in electrolyte additive methods; (ii) both Na\u2013Sn alloy and NaCl possess much higher diffusion coefficients than organic components (ROCO2Na and RCH2ONa) and conventional SEIs, enabling fast ion diffusion and restraining the initiation of Na dendrites; (iii) the high Young's moduli of the Na\u2013Sn alloy and NaCl can also help suppress the growth of Na dendrites. With the above excellent properties, the SnCl4\u2013Na electrode provides an ultralong cycling stability with a stable voltage polarization (\u223c100 mV) for 4000 h with a cycling capacity of 3 mA h cm\u22122 at 2 mA cm\u22122. Moreover, the SnCl4\u2013Na electrode also shows excellent cycling stability for \u223c1500 h even under rather tough conditions (5 mA h cm\u22122, 5 mA cm\u22122). In addition, benefiting from the durable SEI layer, a SnCl4\u2013Na|FeS2 full cell can deliver a stable capacity of \u223c350 mA h g\u22121 for 380 cycles.", "question": "What's the anode?", "answer": "Na metal", "answer_start": 45}
{"document_id": 75710, "context": "Herein, we fabricated two artificial SEIs on Na metal anodes via similar chemical replacement reactions between Na metal and SnCl4 liquid or SnCl2 additive dissolved in diethylene glycol dimethyl ether (DGM). According to X-ray photoelectron spectroscopy (XPS) depth-profiling results, the SnCl4 liquid treatment leads to a uniform and high ionic diffusion artificial SEI consisting of a simultaneously generated Na\u2013Sn alloy and NaCl, whereas the SnCl2 additive results in a disordered and heterogeneous artificial SEI (Na\u2013Sn alloy, NaCl, Sn metal, organo-chloride, ROCO2Na and RCH2ONa) due to the heterogeneous reaction between the Na metal anode and SnCl2/DGM solvent. It is found that the cycling performance of the SnCl4\u2013Na electrodes is highly superior to that of the SnCl2\u2013Na electrodes, which is mainly ascribed to the uniformity and ionic diffusion distinction of the two artificial SEIs. The importance of homogeneous and high ionic diffusion properties for the artificial SEI is also demonstrated by simulation results. Overall, the artificial SEI of SnCl4\u2013Na electrodes can afford three key advantages: (i) the simple and controllable fabrication leads to a homogeneous artificial SEI consisting of uniformly distributed Na\u2013Sn alloy and NaCl, avoiding the non-uniform products caused by the side reactions that commonly exist in electrolyte additive methods; (ii) both Na\u2013Sn alloy and NaCl possess much higher diffusion coefficients than organic components (ROCO2Na and RCH2ONa) and conventional SEIs, enabling fast ion diffusion and restraining the initiation of Na dendrites; (iii) the high Young's moduli of the Na\u2013Sn alloy and NaCl can also help suppress the growth of Na dendrites. With the above excellent properties, the SnCl4\u2013Na electrode provides an ultralong cycling stability with a stable voltage polarization (\u223c100 mV) for 4000 h with a cycling capacity of 3 mA h cm\u22122 at 2 mA cm\u22122. Moreover, the SnCl4\u2013Na electrode also shows excellent cycling stability for \u223c1500 h even under rather tough conditions (5 mA h cm\u22122, 5 mA cm\u22122). In addition, benefiting from the durable SEI layer, a SnCl4\u2013Na|FeS2 full cell can deliver a stable capacity of \u223c350 mA h g\u22121 for 380 cycles.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75710, "context": "Herein, we fabricated two artificial SEIs on Na metal anodes via similar chemical replacement reactions between Na metal and SnCl4 liquid or SnCl2 additive dissolved in diethylene glycol dimethyl ether (DGM). According to X-ray photoelectron spectroscopy (XPS) depth-profiling results, the SnCl4 liquid treatment leads to a uniform and high ionic diffusion artificial SEI consisting of a simultaneously generated Na\u2013Sn alloy and NaCl, whereas the SnCl2 additive results in a disordered and heterogeneous artificial SEI (Na\u2013Sn alloy, NaCl, Sn metal, organo-chloride, ROCO2Na and RCH2ONa) due to the heterogeneous reaction between the Na metal anode and SnCl2/DGM solvent. It is found that the cycling performance of the SnCl4\u2013Na electrodes is highly superior to that of the SnCl2\u2013Na electrodes, which is mainly ascribed to the uniformity and ionic diffusion distinction of the two artificial SEIs. The importance of homogeneous and high ionic diffusion properties for the artificial SEI is also demonstrated by simulation results. Overall, the artificial SEI of SnCl4\u2013Na electrodes can afford three key advantages: (i) the simple and controllable fabrication leads to a homogeneous artificial SEI consisting of uniformly distributed Na\u2013Sn alloy and NaCl, avoiding the non-uniform products caused by the side reactions that commonly exist in electrolyte additive methods; (ii) both Na\u2013Sn alloy and NaCl possess much higher diffusion coefficients than organic components (ROCO2Na and RCH2ONa) and conventional SEIs, enabling fast ion diffusion and restraining the initiation of Na dendrites; (iii) the high Young's moduli of the Na\u2013Sn alloy and NaCl can also help suppress the growth of Na dendrites. With the above excellent properties, the SnCl4\u2013Na electrode provides an ultralong cycling stability with a stable voltage polarization (\u223c100 mV) for 4000 h with a cycling capacity of 3 mA h cm\u22122 at 2 mA cm\u22122. Moreover, the SnCl4\u2013Na electrode also shows excellent cycling stability for \u223c1500 h even under rather tough conditions (5 mA h cm\u22122, 5 mA cm\u22122). In addition, benefiting from the durable SEI layer, a SnCl4\u2013Na|FeS2 full cell can deliver a stable capacity of \u223c350 mA h g\u22121 for 380 cycles.", "question": "What's the anode?", "answer": "Na metal", "answer_start": 633}
{"document_id": 75671, "context": "In this work, we carry out classical reactive molecular dynamics (MD) simulations for studying the initial formation of SEI films occurring by Li oxidation and simultaneous decomposition of electrolyte (salt and solvent) molecules in the liquid phase in contact with the Li-metal electrode. We use lithium hexafluorophosphate (LiPF6) as a salt because its reductive decomposition has been pointed as critical on the SEI formation and lithium trifluoromethanesulfonate (lithium triflate or LiTF) that has shown interesting performance in various systems. We study the behavior of the various system components (i.e. Li-metal anode slab, and salt and solvent molecules) when the electrolyte solution is put in contact with the Li metal surface. We follow the evolution of various events including the lithium metal expansion/dissolution, salt and solvent decomposition, and initial nucleation of the SEI intermediates and products as well as the electron exchange among the species. We aim to identify the effects of electrolyte composition on the Li-metal anode behavior and the SEI formation and growth at open circuit conditions. We focus only on the initial stages of SEI formation, concentrated in a specific part of the battery system, and do not examine the Li deposition events occurring when an ionic flux arrives at the anode during charge, and the effects of an applied field. To gain further understanding of the structures and mechanisms of the initial stages of SEI formation, density functional theory (DFT) calculations on initial Li\u2013F were used to evaluate SEI fragments observed in MD simulations. Once optimized structures of such fragments are obtained, we investigated the fragment clustering processes found at initial stages of SEI nucleation. These simulations provide preliminary estimations for the energies of formation and clustering of LiF fragments.", "question": "What's the anode?", "answer": "Li-metal", "answer_start": 615}
{"document_id": 75671, "context": "In this work, we carry out classical reactive molecular dynamics (MD) simulations for studying the initial formation of SEI films occurring by Li oxidation and simultaneous decomposition of electrolyte (salt and solvent) molecules in the liquid phase in contact with the Li-metal electrode. We use lithium hexafluorophosphate (LiPF6) as a salt because its reductive decomposition has been pointed as critical on the SEI formation and lithium trifluoromethanesulfonate (lithium triflate or LiTF) that has shown interesting performance in various systems. We study the behavior of the various system components (i.e. Li-metal anode slab, and salt and solvent molecules) when the electrolyte solution is put in contact with the Li metal surface. We follow the evolution of various events including the lithium metal expansion/dissolution, salt and solvent decomposition, and initial nucleation of the SEI intermediates and products as well as the electron exchange among the species. We aim to identify the effects of electrolyte composition on the Li-metal anode behavior and the SEI formation and growth at open circuit conditions. We focus only on the initial stages of SEI formation, concentrated in a specific part of the battery system, and do not examine the Li deposition events occurring when an ionic flux arrives at the anode during charge, and the effects of an applied field. To gain further understanding of the structures and mechanisms of the initial stages of SEI formation, density functional theory (DFT) calculations on initial Li\u2013F were used to evaluate SEI fragments observed in MD simulations. Once optimized structures of such fragments are obtained, we investigated the fragment clustering processes found at initial stages of SEI nucleation. These simulations provide preliminary estimations for the energies of formation and clustering of LiF fragments.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75671, "context": "In this work, we carry out classical reactive molecular dynamics (MD) simulations for studying the initial formation of SEI films occurring by Li oxidation and simultaneous decomposition of electrolyte (salt and solvent) molecules in the liquid phase in contact with the Li-metal electrode. We use lithium hexafluorophosphate (LiPF6) as a salt because its reductive decomposition has been pointed as critical on the SEI formation and lithium trifluoromethanesulfonate (lithium triflate or LiTF) that has shown interesting performance in various systems. We study the behavior of the various system components (i.e. Li-metal anode slab, and salt and solvent molecules) when the electrolyte solution is put in contact with the Li metal surface. We follow the evolution of various events including the lithium metal expansion/dissolution, salt and solvent decomposition, and initial nucleation of the SEI intermediates and products as well as the electron exchange among the species. We aim to identify the effects of electrolyte composition on the Li-metal anode behavior and the SEI formation and growth at open circuit conditions. We focus only on the initial stages of SEI formation, concentrated in a specific part of the battery system, and do not examine the Li deposition events occurring when an ionic flux arrives at the anode during charge, and the effects of an applied field. To gain further understanding of the structures and mechanisms of the initial stages of SEI formation, density functional theory (DFT) calculations on initial Li\u2013F were used to evaluate SEI fragments observed in MD simulations. Once optimized structures of such fragments are obtained, we investigated the fragment clustering processes found at initial stages of SEI nucleation. These simulations provide preliminary estimations for the energies of formation and clustering of LiF fragments.", "question": "What's the anode?", "answer": " Li-metal", "answer_start": 1045}
{"document_id": 75672, "context": "Driven by the urgent demand for electrical energy storage in electric vehicles, rechargeable devices with high energy densities and long cycle life continue to attract great interest. Lithium-ion batteries (LIBs) have attracted increasing attention over the past few decades owing to many merits, including high energy density, no memory effect, and good safety. However, making further improvements in their energy density whilst maintaining high safety remains highly challenging, inhibiting the scale-up of their applications. Developing new electrode materials is one of the most efficient ways to achieve LIBs with high energy and high safety. Silicon (Si) is considered to be a promising replacement for the graphite anodes in conventional LIBs, due to its ultrahigh specific capacity (4200 mA h g\u22121, ten times that of graphite), low working potential (ca. 0.4 V versus Li+/Li), natural abundance, high safety and environmentally benign nature. Unfortunately, Si has a low intrinsic electronic conductivity and this restricts charge transfer within Si anodes during the charge\u2013discharge process. Moreover, the large volume change (>300%) of the Si anode during the lithiation/delithiation process leads to drastic particle pulverization and uncontrollable growth of a solid electrolyte interphase (SEI), leading to electrical contact loss between the active materials themselves or the active materials and current collectors. All these inherent problems lead to Si anodes having poor rate performance, low coulombic efficiency (CE) and fast capacity decay on cycling.", "question": "What's the anode?", "answer": "graphite ", "answer_start": 714}
{"document_id": 75672, "context": "Driven by the urgent demand for electrical energy storage in electric vehicles, rechargeable devices with high energy densities and long cycle life continue to attract great interest. Lithium-ion batteries (LIBs) have attracted increasing attention over the past few decades owing to many merits, including high energy density, no memory effect, and good safety. However, making further improvements in their energy density whilst maintaining high safety remains highly challenging, inhibiting the scale-up of their applications. Developing new electrode materials is one of the most efficient ways to achieve LIBs with high energy and high safety. Silicon (Si) is considered to be a promising replacement for the graphite anodes in conventional LIBs, due to its ultrahigh specific capacity (4200 mA h g\u22121, ten times that of graphite), low working potential (ca. 0.4 V versus Li+/Li), natural abundance, high safety and environmentally benign nature. Unfortunately, Si has a low intrinsic electronic conductivity and this restricts charge transfer within Si anodes during the charge\u2013discharge process. Moreover, the large volume change (>300%) of the Si anode during the lithiation/delithiation process leads to drastic particle pulverization and uncontrollable growth of a solid electrolyte interphase (SEI), leading to electrical contact loss between the active materials themselves or the active materials and current collectors. All these inherent problems lead to Si anodes having poor rate performance, low coulombic efficiency (CE) and fast capacity decay on cycling.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75672, "context": "Driven by the urgent demand for electrical energy storage in electric vehicles, rechargeable devices with high energy densities and long cycle life continue to attract great interest. Lithium-ion batteries (LIBs) have attracted increasing attention over the past few decades owing to many merits, including high energy density, no memory effect, and good safety. However, making further improvements in their energy density whilst maintaining high safety remains highly challenging, inhibiting the scale-up of their applications. Developing new electrode materials is one of the most efficient ways to achieve LIBs with high energy and high safety. Silicon (Si) is considered to be a promising replacement for the graphite anodes in conventional LIBs, due to its ultrahigh specific capacity (4200 mA h g\u22121, ten times that of graphite), low working potential (ca. 0.4 V versus Li+/Li), natural abundance, high safety and environmentally benign nature. Unfortunately, Si has a low intrinsic electronic conductivity and this restricts charge transfer within Si anodes during the charge\u2013discharge process. Moreover, the large volume change (>300%) of the Si anode during the lithiation/delithiation process leads to drastic particle pulverization and uncontrollable growth of a solid electrolyte interphase (SEI), leading to electrical contact loss between the active materials themselves or the active materials and current collectors. All these inherent problems lead to Si anodes having poor rate performance, low coulombic efficiency (CE) and fast capacity decay on cycling.", "question": "What's the anode?", "answer": "Si ", "answer_start": 1055}
{"document_id": 75673, "context": "All electrochemical measurements were carried out on a CHI 660E electrochemical workstation. The electrochemical properties of the prepared electrodes were tested using a three-electrode system in 1 M H2SO4 aqueous electrolyte. A platinum plate and a saturated calomel electrode (SCE) served as the counter electrode and the reference electrode, respectively. N-PCNFAs and PCNFAs sandwiched tightly between two pieces of 304 stainless steel meshes were directly used as the binder/additive-free working electrodes held by a clamp. To investigate the electrochemical properties, cyclic voltammetry (CV), galvanostatic charge\u2013discharge (GCD) and electrochemical impedance spectroscopy (EIS, a frequency response analysis over the frequency range from 100 kHz to 10 mHz) were carried out. The specific capacitance of the electrode material was calculated from discharge curves according to the following equation (eqn (1)): where Cm is the specific capacitance (F g\u22121), I is the constant discharge current (A), \u0394t is the discharge time (s), m is the total mass of the active material (g) and \u0394V is the set potential window (V).", "question": "What's the electrolyte?", "answer": "1 M H2SO4 aqueous", "answer_start": 197}
{"document_id": 75674, "context": "Semiconducting polymers swell in typical organic solvents allowing ion penetration and high transconductance. However, for biosensing applications it is essential to operate in aqueous environments. Due to the non-polar nature of polymers, this limits their ability to swell and thus limits performance in aqueous media. A biphasic electrolyte platform developed by Duong et al. incorporates two immiscible electrolytes, an organic layer in direct contact with the polymer and aqueous layer on top. The former is selected because it allows ion penetration into P3HT so it can operate as an OECT, whilst the less dense aqueous layer interfaces with the biological environment of interest. This development opens the potential to utilise a wide range of organic semiconducting polymers that have been previously developed over the past few decades for transistor and solar cell applications.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75679, "context": "The anisotropic expansion of primary grains, especially at a high state of charge (SOC), results in microcracks in NCM-based secondary particles. The morphology changes of the LLO microspheres after 200 cycles at the cut-offs of 4.8 V and 4.5 V are studied by SEM in Fig. S3.\u2020 The LLO microspheres cycled at the cut-off of 4.8 V show some obvious cracks, especially for large particles. But for the LLO particles cycled at 4.5 V, there are no obvious cracks. The structural evolutions of the LLOs at the cut-offs of 4.8 V and 4.5 V are investigated by STEM and EELS, as shown in Fig. 4 and S4\u2013S8.\u2020 The cross-sections of both cycled LLOs are shown in Fig. S8,\u2020 in which the porous structure can still be found. The elemental maps exhibit heterogeneous distribution of TM elements in both cycled LLOs (Fig. S5 and S6\u2020). The intergranular space is mainly filled with F and C containing compounds while the surface is mainly coated with P containing compounds for both cycled LLOs. The low magnification HAADF-STEM image (Fig. 4(a)) shows some microcracks in the cycled LLOs at the cut-off of 4.8 V. The high resolution HAADF-STEM image with the FFT and inverse FFT patterns (Fig. 4(b and c)) confirms the entire transformation from layered to rock-salt phases on the surface of LLOs at the cut-off of 4.8 V. The LLOs at the cut-off of 4.5 V undergo transitions from layered to layered/rock-salt mixed and rock-salt phases over long-term cycling (Fig. 4(d\u2013f)). These results confirm the mitigated phase transition for LLOs over long-term cycling at the low cut-off of 4.5 V, which is probably ascribed to the reduced side reaction on the electrode/electrolyte interface.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75681, "context": "Hybrid organic\u2013inorganic crystals are unique materials that have been attracting increasing interest in the last few years due to their physical properties and potential applications in different fields, such as photovoltaics, lithium batteries, and photomechanic materials, between others. Among these applications, the development of high conductivity solid state electrolytes for fuel cells, batteries and solar cells is one of the most explored areas, in comparison with the polymers electrolytes that generally show low conductivity. In this sense, they are comparable with the classical ceramic conductors, such as doped lithium titanium phosphate, that allows fast ion transport. However, these materials present the considerable disadvantage of fragility and, in some cases, more importantly toxicity. In order to overcome this problem, a new type of materials have been proposed: the plastic hybrid materials. Although plastic crystals were described in the 60's, there is no rule to predict which cation and anion combinations will yield plastic crystalline materials and which will form salts that melt before any rotator phase is achieved. It deserves to be noted that a plastic crystal has a long-range structural order but short-range disorder, which is typically due to the occurrence of rotational motions of the constituents. This plastic phase can be seen as a mesophase between the solid and liquid phases that is often found in molecules with globular structures. This means that they are symmetrical around their center (CH4, CCl4, NH4 pentaerythritol, etc.); or they make a sphere by rotation around an axis (cyclohexane, camphor, etc.). The combination of two or more units to form hybrid materials can be desirable to enhance the multifunctionality of the system, for example doping plastic crystalline phases with a lithium imide salt for application as solid electrolytes in lithium batteries. An alternative is to combine the physical properties by tuning different constituents: ferroelectricity from polar molecules and long-range magnetic order from magnetic anions.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75684, "context": "Similar to graphene, carbon nanotubes (CNTs) with a unique 1D tubular structure and excellent electrical conductivity can also be introduced into electrospun CNFs in order to increase the electrochemical activity of the electrospun CNFs and influence their architecture. Growing CNTs on the surface of the electrospun CNFs could be an effective approach to enhance the capacitive performance of electrode materials in SCs. For instance, a symmetrical device based on CNF/CNT hybrid electrodes exhibited a specific capacitance of 3.35 \u00b1 0.05 mF cm\u22122, which was 3.6 times higher than that of a pure CNF electrode-based device (0.91 \u00b1 0.02 mF cm\u22122). A hierarchical nanostructure of CNFs/CNTs was synthesized through a CVD process by using C2H2 as the carbon precursor and Ni nanoparticles on CNFs as catalysts.Fig. 12c shows an SEM image of the CNFs/CNTs nanocomposites, demonstrating the formation of a hierarchical network structure consisting of densely grown CNTs on the surface of the CNFs. The obtained CNFs/CNT electrode showed a specific capacitance of 464.2 F g\u22121 at 0.5 A g\u22121 in 6 M KOH and excellent stability with 97% retention after 10000 cycles. The excellent performance was ascribed to the following aspects: (i) the intimate contact between the CNTs (to provide electrical conduction from the tip of each CNT to the edges and surfaces of the CNFs) and the CNFs; (ii) the interconnected and porous CNFs acting as an excellent path facilitated charge transfer and electrolyte permeation. Hierarchical CNFs/CNT hybrids were prepared via a tubular CVD growth process using Al/Fe composite catalysts. After KOH activation, the tips of CNTs in the hybrids can be well opened at 700 \u00b0C without changing the overall hierarchical structure. More interestingly, the tip-open CNFs/CNT hybrids showed a considerably improved specific capacitance, which increases to 3.3 times that of the pristine one. Moreover, sweep analysis indicated that the diffusion-type capacitance increases by 3.7 times while the Helmholtz-type capacitance increases by only 1.5 times, indicating that the tip-open CNTs contribute to \u223c30% of the increase in double-layer capacitance. In another study, CNFs/CNT scaffolds were fabricated by the electrospinning technique combined with post-carbonization processes. The diameters of CNF skeletons, CNT density on CNF skeletons and length of CNTs were determined by the PAN concentration, Fe(acac)3 concentration in precursor solution and growth time of C2H2 flow, respectively. It was observed that a suitable size of CNF skeletons, CNT density and growth time of CNTs could greatly enhance the overall performance.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75691, "context": "Garnet-structured oxide electrolytes (Li7La3Zr2O12, LLZO) have significant advantage of being chemically and electrochemically stable against Li metals and allow implementation in Li metal batteries. However, a short-circuit failure due to Li penetration through the LLZO electrolyte has remained a crucial issue for safety and is a major hurdle for Li-based batteries to overcome. In, we investigated a mechanism of Li dendrite formation for the crystalline Ta-doped LLZO (LLZTO) electrolyte by examining their energy band structures and defect states using reflection electron energy loss spectroscopy (REELS), scanning photoelectron microscopy (SPEM), and nanoscale charge-based deep level transient spectroscopy (Nano Q-DLTS) techniques. The experimental results revealed that the Schottky barrier height (SBH) was lowered by 0.5 eV due to defect states localized in grain boundaries and that the metallic Li propagation along the grain boundaries is caused by the SBH reduction. Based on analytical results, the laser annealing of LLZTO was performed via bandgap engineering method to suppress the Li dendrite formation by forming a mixed surface layer of amorphous LLZTO and Li2O2, which has a wide bandgap to block the electron injection into the grain boundaries. The electrochemical measurements of laser-treated LLZTO demonstrated that the stability and cycling performance were significantly improved. This study sheds light on the importance of electronic structure, in particular, the defect states to develop high-performance oxide solid electrolytes for Li metal batteries and the practicality of surface modification by laser treatment.", "question": "What's the electrolyte?", "answer": "(Li7La3Zr2O12, LLZO)", "answer_start": 37}
{"document_id": 75691, "context": "Garnet-structured oxide electrolytes (Li7La3Zr2O12, LLZO) have significant advantage of being chemically and electrochemically stable against Li metals and allow implementation in Li metal batteries. However, a short-circuit failure due to Li penetration through the LLZO electrolyte has remained a crucial issue for safety and is a major hurdle for Li-based batteries to overcome. In, we investigated a mechanism of Li dendrite formation for the crystalline Ta-doped LLZO (LLZTO) electrolyte by examining their energy band structures and defect states using reflection electron energy loss spectroscopy (REELS), scanning photoelectron microscopy (SPEM), and nanoscale charge-based deep level transient spectroscopy (Nano Q-DLTS) techniques. The experimental results revealed that the Schottky barrier height (SBH) was lowered by 0.5 eV due to defect states localized in grain boundaries and that the metallic Li propagation along the grain boundaries is caused by the SBH reduction. Based on analytical results, the laser annealing of LLZTO was performed via bandgap engineering method to suppress the Li dendrite formation by forming a mixed surface layer of amorphous LLZTO and Li2O2, which has a wide bandgap to block the electron injection into the grain boundaries. The electrochemical measurements of laser-treated LLZTO demonstrated that the stability and cycling performance were significantly improved. This study sheds light on the importance of electronic structure, in particular, the defect states to develop high-performance oxide solid electrolytes for Li metal batteries and the practicality of surface modification by laser treatment.", "question": "What's the electrolyte?", "answer": "LLZO (LLZTO)", "answer_start": 468}
{"document_id": 75688, "context": "Unique graphene-like metallic Co9S8 with a morphology comprised of interconnected porous nanosheets that form a 3D network has been successfully synthesized by Nazar's group through a microwave solvothermal approach based on the reaction of cobalt chloride and TAA in a mixed solvent of water and triethylenetetramine at 160 \u00b0C for 1.5 h. Microwaves utilize a solvent dipole\u2013microwave interaction that leads to rapidly superheated regions, triggering rapid nucleation and growth of particles. These distinctive synthesis conditions result in the formation of a long-range nanosheet structure of Co9S8 with a broad pore size distribution. N2 adsorption/desorption analysis indicates a high BET surface area of 108 m2 g\u22121 and a very large pore volume of 1.07 cm3 g\u22121 with the majority of pores in the range of 1.2\u201310 nm and the remainder distributed over 10\u201380 nm, indicating a texture incorporating micro-, meso-, and macro-pores. This high surface area and pore volume along with hierarchical porosity are vital to induce high intrinsic LiPS adsorptivity and enhance electrolyte penetration across thick electrodes. Li et al. presented the preparation of a S/C\u2013SnS2 composite by ball milling sublimed sulfur, Ketjen Black, and ultrathin SnS2 nanosheets, where the 2D ultrathin nanosheets, fabricated by a one-pot reaction of SnCl4, TAA, and acetic acid, bring about a remarkably large surface area to enhance immobilization capability for LiPSs. In addition to those conventional methods, some innovative technologies can also delicately control the surface area, porosity, and/or polarity of metal sulfides. As an example, Xiao et al. demonstrated a green water-steam-etched approach for the fabrication of H- and O-incorporated porous TiS2 (HOPT) via heat treatment of a commercial TiS2 ball-milling product. During heat treatment, a mist of droplets from ultrapure water is passed into a quartz tube containing the ball-milled TiS2 using Ar-carrier gas. Interestingly, the time and temperature of water steam etching play pivotal roles in modulating the porosity of HOPT. Increasing the temperature from 100 to 500 \u00b0C, the specific surface area and pore volume of HOPT increase from 12.7 to 47 m2 g\u22121 and from 0.075 to 0.25 cm3 g\u22121, respectively, resulting from the perforation of TiS2 caused by the introduction of hydrogen and oxygen into the S\u2013Ti\u2013S framework during etching. Note that the hydroxyl and thiol groups in HOPT significantly enhance the surface polarity of TiS2, which are also favorable for adsorbing the LiPSs, suppressing the shuttle effect. More laudably, this method possesses excellent generality and can be extended to other TMDs such as CoS2 and NbS2. As reported in a follow-up study, Xiao et al. presented another extremely similar multistep approach to construct sandwich-type NbS2@S@I-doped graphene, which also brings about enhanced polarity and binding affinity for layered NbS2 to ensnare LiPSs.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75692, "context": "Electrochemical testing was performed in a 2032 coin-type cell using Na metal (Sigma Aldrich, USA) as the anode. Electrodes were fabricated by blending the prepared cathode powders (85 wt%), carbon black (10 wt%), and polyvinylidene fluoride (5 wt%) in N-methyl-2-pyrrolidone (Daejung Chem, Korea). The slurry was then cast on aluminum foil (Hohsen Corp., Japan) and pre-dried at 110 \u00b0C in an oven. Then, the electrode was further dried at 110 \u00b0C for 5 h in a vacuum oven, and the disks were punched out of the foil. The electrolyte solution was 0.5 M NaPF6 (Tokyo Chemical Industry, Japan) in a 1:1 volumetric mixture of ethylene carbonate (Sigma Aldrich, USA) and diethyl carbonate (Sigma Aldrich, USA) with 2 vol% fluoroethylene carbonate (Tokyo Chemical Industry, Japan). All cells were prepared in an Ar-filled glovebox (MBRAUN, Germany). The fabricated cathodes and sodium metal anodes were separated by a glass fiber (Advantec, USA) to prevent short circuiting. The loading amount of the active material for all electrodes was 3.0\u20134.0 mg cm\u22122 in the coin-type half-cell. The cells were typically tested in the constant current mode, within the voltage range of 2.0\u20134.3 V versus Na/Na+, where 1C = 150 mA g\u22121. For the full-cell test, pouch-type (3 \u00d7 5 cm) cells were fabricated and tested in the voltage range of 1.0\u20134.1 V at 15 mA g\u22121 at 25 \u00b0C. The loading amount of the active material was 9.5\u201310.0 mg cm\u22122. The anode was fabricated by blending hard carbon (provided by Aekyung Petrochemical, Korea) (80 wt%), carbon black (3 wt%), and polyvinylidene fluoride (17 wt%). The resulting slurry was covered over copper foil and dried at 110 \u00b0C for 5 h in a vacuum oven. The full cell balance was achieved by controlling the capacity ratio of anode to cathode (N/P ratio) at 1.15:1.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75692, "context": "Electrochemical testing was performed in a 2032 coin-type cell using Na metal (Sigma Aldrich, USA) as the anode. Electrodes were fabricated by blending the prepared cathode powders (85 wt%), carbon black (10 wt%), and polyvinylidene fluoride (5 wt%) in N-methyl-2-pyrrolidone (Daejung Chem, Korea). The slurry was then cast on aluminum foil (Hohsen Corp., Japan) and pre-dried at 110 \u00b0C in an oven. Then, the electrode was further dried at 110 \u00b0C for 5 h in a vacuum oven, and the disks were punched out of the foil. The electrolyte solution was 0.5 M NaPF6 (Tokyo Chemical Industry, Japan) in a 1:1 volumetric mixture of ethylene carbonate (Sigma Aldrich, USA) and diethyl carbonate (Sigma Aldrich, USA) with 2 vol% fluoroethylene carbonate (Tokyo Chemical Industry, Japan). All cells were prepared in an Ar-filled glovebox (MBRAUN, Germany). The fabricated cathodes and sodium metal anodes were separated by a glass fiber (Advantec, USA) to prevent short circuiting. The loading amount of the active material for all electrodes was 3.0\u20134.0 mg cm\u22122 in the coin-type half-cell. The cells were typically tested in the constant current mode, within the voltage range of 2.0\u20134.3 V versus Na/Na+, where 1C = 150 mA g\u22121. For the full-cell test, pouch-type (3 \u00d7 5 cm) cells were fabricated and tested in the voltage range of 1.0\u20134.1 V at 15 mA g\u22121 at 25 \u00b0C. The loading amount of the active material was 9.5\u201310.0 mg cm\u22122. The anode was fabricated by blending hard carbon (provided by Aekyung Petrochemical, Korea) (80 wt%), carbon black (3 wt%), and polyvinylidene fluoride (17 wt%). The resulting slurry was covered over copper foil and dried at 110 \u00b0C for 5 h in a vacuum oven. The full cell balance was achieved by controlling the capacity ratio of anode to cathode (N/P ratio) at 1.15:1.", "question": "What's the anode?", "answer": "Na metal", "answer_start": 69}
{"document_id": 75692, "context": "Electrochemical testing was performed in a 2032 coin-type cell using Na metal (Sigma Aldrich, USA) as the anode. Electrodes were fabricated by blending the prepared cathode powders (85 wt%), carbon black (10 wt%), and polyvinylidene fluoride (5 wt%) in N-methyl-2-pyrrolidone (Daejung Chem, Korea). The slurry was then cast on aluminum foil (Hohsen Corp., Japan) and pre-dried at 110 \u00b0C in an oven. Then, the electrode was further dried at 110 \u00b0C for 5 h in a vacuum oven, and the disks were punched out of the foil. The electrolyte solution was 0.5 M NaPF6 (Tokyo Chemical Industry, Japan) in a 1:1 volumetric mixture of ethylene carbonate (Sigma Aldrich, USA) and diethyl carbonate (Sigma Aldrich, USA) with 2 vol% fluoroethylene carbonate (Tokyo Chemical Industry, Japan). All cells were prepared in an Ar-filled glovebox (MBRAUN, Germany). The fabricated cathodes and sodium metal anodes were separated by a glass fiber (Advantec, USA) to prevent short circuiting. The loading amount of the active material for all electrodes was 3.0\u20134.0 mg cm\u22122 in the coin-type half-cell. The cells were typically tested in the constant current mode, within the voltage range of 2.0\u20134.3 V versus Na/Na+, where 1C = 150 mA g\u22121. For the full-cell test, pouch-type (3 \u00d7 5 cm) cells were fabricated and tested in the voltage range of 1.0\u20134.1 V at 15 mA g\u22121 at 25 \u00b0C. The loading amount of the active material was 9.5\u201310.0 mg cm\u22122. The anode was fabricated by blending hard carbon (provided by Aekyung Petrochemical, Korea) (80 wt%), carbon black (3 wt%), and polyvinylidene fluoride (17 wt%). The resulting slurry was covered over copper foil and dried at 110 \u00b0C for 5 h in a vacuum oven. The full cell balance was achieved by controlling the capacity ratio of anode to cathode (N/P ratio) at 1.15:1.", "question": "What's the electrolyte?", "answer": "0.5 M NaPF6", "answer_start": 546}
{"document_id": 75694, "context": "Though oxygen anion redox processes remarkably boost the specific capacity of LLOs, they trigger some intractable issues, such as voltage/capacity fade, voltage hysteresis, low initial Coulombic efficiency, and inferior rate capability. It has been demonstrated that the voltage hysteresis is caused by the poor kinetics of anionic redox reactions and grows progressively with overoxidation of lattice oxygen anions. Continuous side reactions between overoxidized oxygen anions and organic electrolytes give rise to a thick cathode electrolyte interphase (CEI) film, which deteriorates the interfacial charge-transfer kinetics. Besides, the oxygen anion redox reactions greatly affect the stability of the cationic redox chemistry of these 3d-TM LLOs. Namely, the oxidation of oxygen anions is usually accompanied by irreversible TM migration into neighboring Li 3a vacancies, resulting in structural transformation from the layered to spinel and/or rock-salt phases, which further leads to capacity/voltage fade. Strategies for mitigation of these issues have focused on surface coating, inactive-ion doping, a composition-graded structure, and optimization of chemical composition. In particular, regulating the anionic redox behaviors by tuning the cation arrangement and oxygen stacking sequence has captured great attention recently. Although some intriguing progress has been made, it is a long way towards their real-world implementation in high energy-density LIBs.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75698, "context": "For further confirmation of the above electrochemical reaction mechanism, the HRTEM images of the discharged/charged electrodes were recorded. The ex situ images (ESI Fig. S8\u2020) clearly showed the presence of the lattice fringes related to the \u03b2-MnS phase, thereby confirming the mechanism proposed in the present study. From these results, it is evident that such reaction mechanisms demonstrate electrochemical stability for prolonged cycling of the proposed composite electrode. The early variation in the specific capacity of the present electrode during cycling (Fig. 4c) is mostly related to the gradual activation of nanostructured electrodes. However, it remains essential to identify the individual contribution of the two reactions (intercalation and conversion) in the present electrochemical regulation to explain the variation in the long-term cycling curve (Fig. 4c) of the present \u03b1-MnS@NS-C electrode. To achieve this, further studies mostly related to in situ characterizations including the galvanostatic intermittent titration technique (GITT) and potentiostatic electrochemical impedance spectroscopy (PEIS) combined with separate examinations of the voltage profiles over regular cycling spans are required. However, the high reversibility of the present intercalation-cum-conversion reaction mechanism is actively supported by the conductive carbon network formed from the co-doping of the N and S in graphitic carbon. The unique electrode morphology and carbon matrix can improve electrical connectivity. Moreover, they impart structural stability by accommodating the volume changes caused by structural transitions and prevent polysulfide dissolution into the electrolyte during consecutive lithiation/delithiation processes. This, in turn, can enhance the electrochemical performance and cyclability of the proposed composite electrode.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75699, "context": "In addition to the room-temperature performance investigation, we also explored the possibility of operating the hybrid supercapacitor at low temperatures. Our previous research studies have demonstrated that rechargeable batteries using H3O+ ions as charge carriers can operate even at a low temperature of \u221270 \u00b0C. Therefore, it is highly possible that this hybrid supercapacitor can operate well in such cold environments. To illustrate this assumption, we evaluated its electrochemical performance at a low temperature of \u221270 \u00b0C. It can be observed from Fig. S19\u2020 that the acid electrolyte containing Mn2+ has frozen at \u221270 \u00b0C. However, the hybrid supercapacitor still displays a discharge specific capacitance of 163.6 F g\u22121 at 0.1 A g\u22121 and 62.2 F g\u22121 at 0.5 A g\u22121 (Fig. 5a). Additionally, the Ragone plot in Fig. 5b shows that the hybrid supercapacitor exhibits a maximum energy density of 27.4 W h kg\u22121 and power density of 605 W kg\u22121 at \u221270 \u00b0C. More surprisingly, the specific capacitance of the hybrid supercapacitor can maintain approximately 100% of the original capacitance over 1000 cycles at \u221270 \u00b0C (Fig. 5c). Such excellent low-temperature performance of the hybrid supercapacitor is associated with the high ionic conductivity of the electrolyte. The DSC measurements show that the freezing point of the acid electrolyte containing Mn2+ is \u221240.2 \u00b0C (Fig. S20\u2020), which is lower than that of the 2 M MnSO4 solution (\u221211 \u00b0C, Fig. S21\u2020). Surprisingly, it is found that this acid electrolyte containing Mn2+ can still show a decent ionic conductivity at \u221270 \u00b0C (2.6 mS cm\u22121), obtained from EIS data displayed in Fig. S22 (see the related calculations in the ESI\u2020).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75732, "context": "Herein, a Li/LiV2(PO4)3 primary battery was proposed and studied for the first time. The unique NASICON structure of monoclinic LiV2(PO4)3 facilitated Li+ diffusion, ensuring superior rate capability and low-temperature performance of the battery. However, the short shelf life of the Li/LiV2(PO4)3 primary batteries hinders their practical applications. The shelf life of the Li/LiV2(PO4)3 primary batteries was improved by optimizing the electrolyte composition. It was found that the corrosion of the Al foil triggered by the organic radical cations generated from the electrochemical oxidation of EC at high potentials leads to the self-discharge of the Li/LiV2(PO4)3 primary battery. When EC was replaced by PC, the corrosion of the Al foil was alleviated, and the shelf life of the Li/LiV2(PO4)3 primary battery was significantly improved. However, the loss of capacity still occurred after storage, which is ascribed to the oxidation decomposition of the electrolyte on the surface of the LiV2(PO4)3 cathode. A slow two-phase transition process from the LiV2(PO4)3 phase to the Li3V2(PO4)3 phase with the reduction of V4+ to low-valence V was characterized by the in situ XRD of the LiV2(PO4)3 cathode during its storage; this process was accompanied by the spontaneous insertion of Li back into LiV2(PO4)3. It was found that LiBOB as an additive effectively helps to improve the shelf life of the Li/LiV2(PO4)3 primary battery by alleviating the side reaction between LiV2(PO4)3 and electrolyte according to the XPS results, 100% of capacity could be maintained after one-month storage. Meanwhile, the Li/LiV2(PO4)3 primary battery exhibited superior rate capability and low-temperature performance: 86% energy could be maintained at 50C and 63% energy could be maintained at \u221240 \u00b0C and 0.1C, which was substantially better than the performance of the Li/MnO2 primary battery. Thus, our Li/LiV2(PO4)3 primary battery is an ideal candidate for applications in extreme situations.", "question": "What's the cathode?", "answer": " LiV2(PO4)3", "answer_start": 995}
{"document_id": 75732, "context": "Herein, a Li/LiV2(PO4)3 primary battery was proposed and studied for the first time. The unique NASICON structure of monoclinic LiV2(PO4)3 facilitated Li+ diffusion, ensuring superior rate capability and low-temperature performance of the battery. However, the short shelf life of the Li/LiV2(PO4)3 primary batteries hinders their practical applications. The shelf life of the Li/LiV2(PO4)3 primary batteries was improved by optimizing the electrolyte composition. It was found that the corrosion of the Al foil triggered by the organic radical cations generated from the electrochemical oxidation of EC at high potentials leads to the self-discharge of the Li/LiV2(PO4)3 primary battery. When EC was replaced by PC, the corrosion of the Al foil was alleviated, and the shelf life of the Li/LiV2(PO4)3 primary battery was significantly improved. However, the loss of capacity still occurred after storage, which is ascribed to the oxidation decomposition of the electrolyte on the surface of the LiV2(PO4)3 cathode. A slow two-phase transition process from the LiV2(PO4)3 phase to the Li3V2(PO4)3 phase with the reduction of V4+ to low-valence V was characterized by the in situ XRD of the LiV2(PO4)3 cathode during its storage; this process was accompanied by the spontaneous insertion of Li back into LiV2(PO4)3. It was found that LiBOB as an additive effectively helps to improve the shelf life of the Li/LiV2(PO4)3 primary battery by alleviating the side reaction between LiV2(PO4)3 and electrolyte according to the XPS results, 100% of capacity could be maintained after one-month storage. Meanwhile, the Li/LiV2(PO4)3 primary battery exhibited superior rate capability and low-temperature performance: 86% energy could be maintained at 50C and 63% energy could be maintained at \u221240 \u00b0C and 0.1C, which was substantially better than the performance of the Li/MnO2 primary battery. Thus, our Li/LiV2(PO4)3 primary battery is an ideal candidate for applications in extreme situations.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75732, "context": "Herein, a Li/LiV2(PO4)3 primary battery was proposed and studied for the first time. The unique NASICON structure of monoclinic LiV2(PO4)3 facilitated Li+ diffusion, ensuring superior rate capability and low-temperature performance of the battery. However, the short shelf life of the Li/LiV2(PO4)3 primary batteries hinders their practical applications. The shelf life of the Li/LiV2(PO4)3 primary batteries was improved by optimizing the electrolyte composition. It was found that the corrosion of the Al foil triggered by the organic radical cations generated from the electrochemical oxidation of EC at high potentials leads to the self-discharge of the Li/LiV2(PO4)3 primary battery. When EC was replaced by PC, the corrosion of the Al foil was alleviated, and the shelf life of the Li/LiV2(PO4)3 primary battery was significantly improved. However, the loss of capacity still occurred after storage, which is ascribed to the oxidation decomposition of the electrolyte on the surface of the LiV2(PO4)3 cathode. A slow two-phase transition process from the LiV2(PO4)3 phase to the Li3V2(PO4)3 phase with the reduction of V4+ to low-valence V was characterized by the in situ XRD of the LiV2(PO4)3 cathode during its storage; this process was accompanied by the spontaneous insertion of Li back into LiV2(PO4)3. It was found that LiBOB as an additive effectively helps to improve the shelf life of the Li/LiV2(PO4)3 primary battery by alleviating the side reaction between LiV2(PO4)3 and electrolyte according to the XPS results, 100% of capacity could be maintained after one-month storage. Meanwhile, the Li/LiV2(PO4)3 primary battery exhibited superior rate capability and low-temperature performance: 86% energy could be maintained at 50C and 63% energy could be maintained at \u221240 \u00b0C and 0.1C, which was substantially better than the performance of the Li/MnO2 primary battery. Thus, our Li/LiV2(PO4)3 primary battery is an ideal candidate for applications in extreme situations.", "question": "What's the cathode?", "answer": "LiV2(PO4)3", "answer_start": 1190}
{"document_id": 75743, "context": "The morphologies of NF, MoP/NF, NiCo-LDH/NF, and MoP@NiCo-LDH/NF-20 were also characterized by SEM (Fig. 3a, b and S2\u2020). It can be seen that the folded lamellar structure is uniformly grown on and aggregated into a tremella shape on the smooth surface of NF, which can promote the increase in both specific surface area and active sites. In addition, the electrodeposition time was optimized to obtain MoP@NiCo-LDH/NF-x (Fig. S3\u2020). When the electrodeposition time is 10 minutes, the MoP surface is coated with sparse NiCo-LDH nanosheets. With the increase of electrodeposition time, the MoP surface is coated with relatively dense NiCo-LDH nanosheets. However, as the electrodeposition time increases to 30 minutes, the NiCo-LDH nanosheets become more crowded. Too loose or too tight a structure is not conducive to the movement of ions in the electrolyte and charge transfer, thus affecting the performance of electrocatalysis, so MoP@NiCo-LDH/NF-20 should have relatively more active sites.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75714, "context": "According to the SEM images in Fig. 4c and S16,\u2020 the basic skeleton of FeCO3@IF after OER remains almost the same compared with the electrode before OER. However, the FeCO3 cubes are covered with lots of nanosheets, which grow vertically on the cubes and are connected to each other. According to Fig. S17,\u2020 it is easy to observe the formation of a nanosheet array on the surface of the area of FeCO3@IF without FeCO3 cubes, which is the same as the surface morphology of the FeCO3 cubes after the OER process (Fig. 4c). The TEM image in Fig. 4d further confirms the formation of nanosheets. The blurry lattice fringes in the HRTEM image (the inset in Fig. 4d) suggest that the newly generated iron oxo/hydroxides have a high degree of amorphization. Therefore, the generated iron-based oxo/hydroxides are not observed in the XRD pattern (Fig. 4a). Notably, the high degree of amorphization is beneficial for the exposure of more catalytic sites and accelerating mass transfer. Furthermore, the phases with a high degree of amorphization also possess abundant unsaturated electronic configurations, which may improve the adsorption of reactants. The amorphous iron oxo/hydroxides are efficient catalytic sites for OER. More importantly, the vertical nanosheet arrays can promote the penetration of the electrolyte and bubble diffusion compared with cumulate nanoparticles and interlaced nanowires (Fig. S18\u2020). The in situ generated interconnected nanosheets also have a strong interaction with the IF substrate, which is beneficial for maintaining good structural stability and high electron transfer efficiency. According to the SEM and XRD results, FeCO3 does not completely transform into oxo/hydroxide nanosheets, because of diffusional and electrochemical limitations. The partial surface in situ self-reconstruction causes FeCO3@IF to obtain novel and stable hierarchical structures during the OER process (Fig. 4e), with improved mechanical strength and rich diffusion pathways. Therefore, FeCO3@IF shows high OER catalytic activity and stability.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75726, "context": "The use of Mg-alloyable metallic anodes is another promising approach to enhancing the viability of MIBs. This is mainly because the Mg alloying/dealloying process occurs slightly above the Mg plating/stripping potentials, and the surface passivation problems of Mg in conventional electrolytes is expected to be alleviated to a great extent. Indeed, reversible Mg alloying/dealloying behavior on bismuth has been confirmed in conventional electrolytes by several researchers (e.g., Bi nanoparticles in Mg(N(SO2CF3)2)2/acetonitrile; Bi nanotubes in Mg(N(SO2CF3)2)2/diglyme; and Bi nanocrystals in Mg(N(SO2CF3)2)2/diglyme). Bi anodes have shown reasonable cyclability and rate performance in a nanometric form. Mg-alloyable Sn was also studied for use as MIB anodes. Sn can deliver a higher specific capacity than Bi (903 mA h g\u22121 for Sn + 2Mg2+ + 4e\u2212 \u2192 Mg2Sn and 385 mA h g\u22121 for 2Bi + 3Mg2+ + 6e\u2212 \u2192 Mg3Bi2) and can alloy/dealloy Mg at a lower potential than Bi (0.15 and 0.25 V vs. Mg/Mg2+ for Sn and Bi, respectively). Despite the theoretical prediction that nanometric Sn can act as a high-capacity MIB anode, pure Sn has shown limited electrochemical performance. For example, though pure Sn delivered a capacity of ca. 900 mA h g\u22121 during the 1st magnesiation (complete conversion of Sn to Mg2Sn), the capacity abruptly dropped to ca. 200\u2013300 mA h g\u22121 after the 1st magnesiation, and continuously declined with repeated charge/discharge (C/D). Furthermore, pure Sn often requires the application of potentials close to, or even lower than, the thermodynamic Mg plating potential for the activation of an alloying process.", "question": "What's the anode?", "answer": "Bi", "answer_start": 623}
{"document_id": 75726, "context": "The use of Mg-alloyable metallic anodes is another promising approach to enhancing the viability of MIBs. This is mainly because the Mg alloying/dealloying process occurs slightly above the Mg plating/stripping potentials, and the surface passivation problems of Mg in conventional electrolytes is expected to be alleviated to a great extent. Indeed, reversible Mg alloying/dealloying behavior on bismuth has been confirmed in conventional electrolytes by several researchers (e.g., Bi nanoparticles in Mg(N(SO2CF3)2)2/acetonitrile; Bi nanotubes in Mg(N(SO2CF3)2)2/diglyme; and Bi nanocrystals in Mg(N(SO2CF3)2)2/diglyme). Bi anodes have shown reasonable cyclability and rate performance in a nanometric form. Mg-alloyable Sn was also studied for use as MIB anodes. Sn can deliver a higher specific capacity than Bi (903 mA h g\u22121 for Sn + 2Mg2+ + 4e\u2212 \u2192 Mg2Sn and 385 mA h g\u22121 for 2Bi + 3Mg2+ + 6e\u2212 \u2192 Mg3Bi2) and can alloy/dealloy Mg at a lower potential than Bi (0.15 and 0.25 V vs. Mg/Mg2+ for Sn and Bi, respectively). Despite the theoretical prediction that nanometric Sn can act as a high-capacity MIB anode, pure Sn has shown limited electrochemical performance. For example, though pure Sn delivered a capacity of ca. 900 mA h g\u22121 during the 1st magnesiation (complete conversion of Sn to Mg2Sn), the capacity abruptly dropped to ca. 200\u2013300 mA h g\u22121 after the 1st magnesiation, and continuously declined with repeated charge/discharge (C/D). Furthermore, pure Sn often requires the application of potentials close to, or even lower than, the thermodynamic Mg plating potential for the activation of an alloying process.", "question": "What's the electrolyte?", "answer": "Mg(N(SO2CF3)2)2/acetonitrile", "answer_start": 503}
{"document_id": 75726, "context": "The use of Mg-alloyable metallic anodes is another promising approach to enhancing the viability of MIBs. This is mainly because the Mg alloying/dealloying process occurs slightly above the Mg plating/stripping potentials, and the surface passivation problems of Mg in conventional electrolytes is expected to be alleviated to a great extent. Indeed, reversible Mg alloying/dealloying behavior on bismuth has been confirmed in conventional electrolytes by several researchers (e.g., Bi nanoparticles in Mg(N(SO2CF3)2)2/acetonitrile; Bi nanotubes in Mg(N(SO2CF3)2)2/diglyme; and Bi nanocrystals in Mg(N(SO2CF3)2)2/diglyme). Bi anodes have shown reasonable cyclability and rate performance in a nanometric form. Mg-alloyable Sn was also studied for use as MIB anodes. Sn can deliver a higher specific capacity than Bi (903 mA h g\u22121 for Sn + 2Mg2+ + 4e\u2212 \u2192 Mg2Sn and 385 mA h g\u22121 for 2Bi + 3Mg2+ + 6e\u2212 \u2192 Mg3Bi2) and can alloy/dealloy Mg at a lower potential than Bi (0.15 and 0.25 V vs. Mg/Mg2+ for Sn and Bi, respectively). Despite the theoretical prediction that nanometric Sn can act as a high-capacity MIB anode, pure Sn has shown limited electrochemical performance. For example, though pure Sn delivered a capacity of ca. 900 mA h g\u22121 during the 1st magnesiation (complete conversion of Sn to Mg2Sn), the capacity abruptly dropped to ca. 200\u2013300 mA h g\u22121 after the 1st magnesiation, and continuously declined with repeated charge/discharge (C/D). Furthermore, pure Sn often requires the application of potentials close to, or even lower than, the thermodynamic Mg plating potential for the activation of an alloying process.", "question": "What's the anode?", "answer": "Mg-alloyable Sn", "answer_start": 710}
{"document_id": 75726, "context": "The use of Mg-alloyable metallic anodes is another promising approach to enhancing the viability of MIBs. This is mainly because the Mg alloying/dealloying process occurs slightly above the Mg plating/stripping potentials, and the surface passivation problems of Mg in conventional electrolytes is expected to be alleviated to a great extent. Indeed, reversible Mg alloying/dealloying behavior on bismuth has been confirmed in conventional electrolytes by several researchers (e.g., Bi nanoparticles in Mg(N(SO2CF3)2)2/acetonitrile; Bi nanotubes in Mg(N(SO2CF3)2)2/diglyme; and Bi nanocrystals in Mg(N(SO2CF3)2)2/diglyme). Bi anodes have shown reasonable cyclability and rate performance in a nanometric form. Mg-alloyable Sn was also studied for use as MIB anodes. Sn can deliver a higher specific capacity than Bi (903 mA h g\u22121 for Sn + 2Mg2+ + 4e\u2212 \u2192 Mg2Sn and 385 mA h g\u22121 for 2Bi + 3Mg2+ + 6e\u2212 \u2192 Mg3Bi2) and can alloy/dealloy Mg at a lower potential than Bi (0.15 and 0.25 V vs. Mg/Mg2+ for Sn and Bi, respectively). Despite the theoretical prediction that nanometric Sn can act as a high-capacity MIB anode, pure Sn has shown limited electrochemical performance. For example, though pure Sn delivered a capacity of ca. 900 mA h g\u22121 during the 1st magnesiation (complete conversion of Sn to Mg2Sn), the capacity abruptly dropped to ca. 200\u2013300 mA h g\u22121 after the 1st magnesiation, and continuously declined with repeated charge/discharge (C/D). Furthermore, pure Sn often requires the application of potentials close to, or even lower than, the thermodynamic Mg plating potential for the activation of an alloying process.", "question": "What's the electrolyte?", "answer": "Mg(N(SO2CF3)2)2/diglyme", "answer_start": 549}
{"document_id": 75715, "context": "The plating and stripping behaviors of the LiF@Po\u2013Li electrodes are observed by SEM after the Li deposition of 1 mA h cm\u22122 at a current density of 0.5 mA cm\u22122 with an EC/DEC:3/7, 1.3 M LiPF6, and 5 wt% FEC electrolyte (Fig. 3). All the electrochemical experiments are performed with carbonate-based electrolytes. It has been well known that the ether-based electrolytes, especially the DME/DOL system, exhibit better electrochemical properties compared to carbonate-based electrolytes in LMBs thanks to their stable SEI layer formation and more freedom to choose additives. However, the ether-based electrolyte is not suitable for various commercial cathode material due to its instability above 4.0 V vs. Li/Li+. In this regard, carbonated-based electrolytes should be explored for their electrochemical properties in upcoming high energy density LMBs. The electrodes are washed with dimethyl carbonate (DMC) to remove residual salts before SEM observation. The Li metal plated on the bare Li electrode shows a mossy, porous and dendritic morphology with an 11.8 \u03bcm thickness and 59% porosity (Fig. 3a, b and ESI Note 1\u2020). In contrast, the Li metal plated on the LiF@Po\u2013Li electrode exhibits a smooth and film-like morphology with significantly reduced porosity (Fig. 3c, d and S7\u2020). The cross-sectional view of the LiF@Po\u2013Li electrode after plating clearly shows that a 6.8 \u03bcm-thick dense Li film is deposited on the LiF@Po\u2013Li electrode with 28% porosity (Fig. 3d). The stripping behavior is also monitored. As shown in Fig. 3e and f, the bare Li electrode has high-density craters with sizes ranging from 10 \u03bcm to 50 \u03bcm after the Li stripping. This non-uniform surface morphology is attributed to the localized current density caused by the inhomogeneous SEI layer. In contrast, the LiF@Po\u2013Li electrode has a smooth and conformal surface without noticeable holes over a large area after Li stripping (Fig. 3g and h). This improvement in plating and stripping behaviors of Li is attributed to the LiF@Po protective layer, which enables a uniform Li ion concentration and current density over the Li electrode by suppressing the electrolyte decomposition.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75715, "context": "The plating and stripping behaviors of the LiF@Po\u2013Li electrodes are observed by SEM after the Li deposition of 1 mA h cm\u22122 at a current density of 0.5 mA cm\u22122 with an EC/DEC:3/7, 1.3 M LiPF6, and 5 wt% FEC electrolyte (Fig. 3). All the electrochemical experiments are performed with carbonate-based electrolytes. It has been well known that the ether-based electrolytes, especially the DME/DOL system, exhibit better electrochemical properties compared to carbonate-based electrolytes in LMBs thanks to their stable SEI layer formation and more freedom to choose additives. However, the ether-based electrolyte is not suitable for various commercial cathode material due to its instability above 4.0 V vs. Li/Li+. In this regard, carbonated-based electrolytes should be explored for their electrochemical properties in upcoming high energy density LMBs. The electrodes are washed with dimethyl carbonate (DMC) to remove residual salts before SEM observation. The Li metal plated on the bare Li electrode shows a mossy, porous and dendritic morphology with an 11.8 \u03bcm thickness and 59% porosity (Fig. 3a, b and ESI Note 1\u2020). In contrast, the Li metal plated on the LiF@Po\u2013Li electrode exhibits a smooth and film-like morphology with significantly reduced porosity (Fig. 3c, d and S7\u2020). The cross-sectional view of the LiF@Po\u2013Li electrode after plating clearly shows that a 6.8 \u03bcm-thick dense Li film is deposited on the LiF@Po\u2013Li electrode with 28% porosity (Fig. 3d). The stripping behavior is also monitored. As shown in Fig. 3e and f, the bare Li electrode has high-density craters with sizes ranging from 10 \u03bcm to 50 \u03bcm after the Li stripping. This non-uniform surface morphology is attributed to the localized current density caused by the inhomogeneous SEI layer. In contrast, the LiF@Po\u2013Li electrode has a smooth and conformal surface without noticeable holes over a large area after Li stripping (Fig. 3g and h). This improvement in plating and stripping behaviors of Li is attributed to the LiF@Po protective layer, which enables a uniform Li ion concentration and current density over the Li electrode by suppressing the electrolyte decomposition.", "question": "What's the electrolyte?", "answer": " 5 wt% FEC", "answer_start": 195}
{"document_id": 75715, "context": "The plating and stripping behaviors of the LiF@Po\u2013Li electrodes are observed by SEM after the Li deposition of 1 mA h cm\u22122 at a current density of 0.5 mA cm\u22122 with an EC/DEC:3/7, 1.3 M LiPF6, and 5 wt% FEC electrolyte (Fig. 3). All the electrochemical experiments are performed with carbonate-based electrolytes. It has been well known that the ether-based electrolytes, especially the DME/DOL system, exhibit better electrochemical properties compared to carbonate-based electrolytes in LMBs thanks to their stable SEI layer formation and more freedom to choose additives. However, the ether-based electrolyte is not suitable for various commercial cathode material due to its instability above 4.0 V vs. Li/Li+. In this regard, carbonated-based electrolytes should be explored for their electrochemical properties in upcoming high energy density LMBs. The electrodes are washed with dimethyl carbonate (DMC) to remove residual salts before SEM observation. The Li metal plated on the bare Li electrode shows a mossy, porous and dendritic morphology with an 11.8 \u03bcm thickness and 59% porosity (Fig. 3a, b and ESI Note 1\u2020). In contrast, the Li metal plated on the LiF@Po\u2013Li electrode exhibits a smooth and film-like morphology with significantly reduced porosity (Fig. 3c, d and S7\u2020). The cross-sectional view of the LiF@Po\u2013Li electrode after plating clearly shows that a 6.8 \u03bcm-thick dense Li film is deposited on the LiF@Po\u2013Li electrode with 28% porosity (Fig. 3d). The stripping behavior is also monitored. As shown in Fig. 3e and f, the bare Li electrode has high-density craters with sizes ranging from 10 \u03bcm to 50 \u03bcm after the Li stripping. This non-uniform surface morphology is attributed to the localized current density caused by the inhomogeneous SEI layer. In contrast, the LiF@Po\u2013Li electrode has a smooth and conformal surface without noticeable holes over a large area after Li stripping (Fig. 3g and h). This improvement in plating and stripping behaviors of Li is attributed to the LiF@Po protective layer, which enables a uniform Li ion concentration and current density over the Li electrode by suppressing the electrolyte decomposition.", "question": "What's the electrolyte?", "answer": "carbonate-based ", "answer_start": 283}
{"document_id": 75716, "context": "Supercapacitors are a class of energy storage devices found commonly in hybrid electric vehicles, camera components and used as backup power systems. One class of supercapacitors, called electric double layer capacitors (EDLCs), are a popular option for commercial applications. In EDLCs, electrolyte ions are adsorbed onto the electrode/electrolyte interface of high-surface area carbon and charge is stored solely via this electrostatic double layer. Due to this charge storage process, the structural integrity of the electrode is maintained resulting in high power densities and cycle lifetimes of over one million cycles. One major drawback of these devices is their low energy density, which limits their use in many applications. To improve the energy density of supercapacitors, many transition metal oxides such as V2O5, Ni(OH)2, Co3O4, RuO2, MnO2 and WO3 have been investigated. Unlike carbon-based materials, transition metal oxides undergo faradaic reactions that facilitate charge storage. Due to accessible redox states, transition metal oxides have much higher energy densities, but most suffer from low conductivity and poor cycling stability. In particular, tungsten oxide has been suggested as a potential alternative for supercapacitor electrode materials due to its redox active properties. Recent efforts have focused on improving tungsten oxide containing supercapacitors including their electrochemical performance, rate, and cycling stability in order to improve this material for energy storage applications.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75717, "context": "For electrochemical activation of the CRLE two electrodes were placed in a beaker in a distance of approximately 10 cm. A reference electrode (Ag/AgCl 3 M KCl) was placed in close proximity to the electrode to be activated. The second CRLE served as inert counter electrode. In screening experiments different activation potentials and polarisation time were tested at room temperature using 0.1 M NaOH as electrolyte (the results are shown in ESI-7\u2020). Polarisation at 1800 mV for 90 s yielded the best electrode performance at short activation time (Table 1).", "question": "What's the electrolyte?", "answer": "0.1 M NaOH", "answer_start": 392}
{"document_id": 75718, "context": "The listed physical parameters are essential for designing a new generation of electronic devices with significantly improved sensitivity and time response. For instance, the high piezoelectric activity of near room temperature ferroelectrics Sn2P2S6, whose Tc \u2248 337 K, can compete with well-known BiFeO3, currently one of the top choices for switchable ferroelectric diodes. Near room temperature spontaneous polarization of Sn2P2S6 can serve as a base for non-volatile ferroelectric random-access memory (FERAM) elements, at the same time significantly miniaturizing the designed systems. The first steps of such practical exploits have been recently observed for layered room-temperature ferroelectric CuInP2S6, demonstrating that reversible polarization switchability with an on/off ratio of about \u223c100 can be achieved for ferroelectric flakes with the thickness reaching an impressive limit of \u223c4 nm. Due to locally controlled ion conductivity and giant negative electrostrictive coefficients, CuInP2S6 is also considered as a solid electrolyte for boosting sodium and lithium battery performance. Similarly, 2D superparaelectric Sn2P2S6 with a large dielectric constant was also proposed for the same purpose. The high photoelectric conversion efficiency of Sn2P2S6 allowed exploration of the ultrafast shift-current behaviour, comparable only to the performance of SbSI, CdSe, and CdS. These properties can be utilised for the novel design of the band edge shift current based photovoltaic devices, pushing the solar cell energy harvesting towards their theoretical limit. Additionally, Sn2P2S6 ferroelectrics have prominent photorefractive properties in the near-infrared spectral region, which makes them suitable for highly efficient acousto-optic and holographic devices.", "question": "What's the electrolyte?", "answer": "CuInP2S6", "answer_start": 999}
{"document_id": 75720, "context": "7Li magic-angle spinning (MAS) ssNMR spectroscopy was performed to trace the local environment of Li. Fig. 2d and S4a\u2020 shows the 7Li projection magic-angle turning and phase-adjusted sideband separation (pjMATPASS) spectra for the pristine, two-cycled and treated LMO. The pristine LMO showed two isotropic peaks resulting from Li in the octahedral site (LiO6). The main peak with a shoulder at around 748 ppm comes from Li in the Li layer and the one at around 1500 ppm can be attributed to Li in the TM layer. For pristine LMO, the small peak at around 0 ppm was due to the residual Li2CO3. The main peaks at around 748 ppm and 1500 ppm remained in the two-cycled LMO samples (Fig. S4a\u2020). The sharp signal with enhanced intensity at around 0 ppm was mainly due to the solid electrolyte interphase (SEI) components, such as Li2CO3 and LiF. The treated T-LMO sample exhibited that some Li-ions remained in the TM layer, as for LMO and two-cycled LMO. The remaining sidebands at around \u00b1250 ppm in T-LMO came from a peak at around 0 ppm. Besides the similar peaks in LMO, a new peak appeared at around 529 ppm in T-LMO, which can be ascribed to Li in the tetrahedral site, like that in LiMn2O4. A broad peak at around 660 ppm corresponds well with that of the Li2Mn4O9 reference with Li in the tetrahedral site (Fig. S4b\u2020). Although a small amount of disordered shells may exist in the T-LMO sample, their intensities are too low to be detected here, which might be overlapped by the strong NMR signal associated with Li contained in the crystalline core of the particles. The T-LMO curve was deconvoluted by the standard reference spectrum (black curve), which showed that T-LMO consists of 35.5% LMO, 16.9% LiMn2O4 and 47.6% Li2Mn4O9. The NMR spectra result provides direct evidence that new spinel phases appear in the T-LMO, which may be due to cation rearrangement.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75728, "context": "For the half-cell tests, the electrochemical properties were evaluated using a CR2032 corn-type cell. The cells were prepared in an Ar-filled glove box with H2O and O2 concentrations <0.1 ppm. Si@CTSC, Si@ALGC, Si@PVDFC and Si/PVDF were used as the anodes (diameter: 14 mm), and Li metal foil was used as the counter electrodes (thickness: 300 \u03bcm and diameter: 12 mm). A Celgard 2400 polypropylene membrane was used as the separator. The electrolyte was 1 M LiPF6 in a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC) (1:1:1 by vol) with 5 wt% fluoroethylene carbonate (FEC). The electrolyte amount was 5 g A h\u22121. The electrochemical tests were carried out after letting the assembled cells stand for 24 hours to ensure full infiltration of the electrolyte. The GCD measurements were carried on a Land CT2001A system from 0.01 to 2.5 V. CV measurements were performed with sweep rates from 0.2 to 1.2 mV s\u22121 using a CHI660E work station. The frequency for the EIS measurements ranged from 100 kHz to 10 mHz. GITT tests were carried out using a constant current pulse with a duration of 10 min and a relaxation process over 10 min.", "question": "What's the anode?", "answer": "Si@CTSC, Si@ALGC, Si@PVDFC and Si/PVDF", "answer_start": 193}
{"document_id": 75728, "context": "For the half-cell tests, the electrochemical properties were evaluated using a CR2032 corn-type cell. The cells were prepared in an Ar-filled glove box with H2O and O2 concentrations <0.1 ppm. Si@CTSC, Si@ALGC, Si@PVDFC and Si/PVDF were used as the anodes (diameter: 14 mm), and Li metal foil was used as the counter electrodes (thickness: 300 \u03bcm and diameter: 12 mm). A Celgard 2400 polypropylene membrane was used as the separator. The electrolyte was 1 M LiPF6 in a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC) (1:1:1 by vol) with 5 wt% fluoroethylene carbonate (FEC). The electrolyte amount was 5 g A h\u22121. The electrochemical tests were carried out after letting the assembled cells stand for 24 hours to ensure full infiltration of the electrolyte. The GCD measurements were carried on a Land CT2001A system from 0.01 to 2.5 V. CV measurements were performed with sweep rates from 0.2 to 1.2 mV s\u22121 using a CHI660E work station. The frequency for the EIS measurements ranged from 100 kHz to 10 mHz. GITT tests were carried out using a constant current pulse with a duration of 10 min and a relaxation process over 10 min.", "question": "What's the electrolyte?", "answer": "1 M LiPF6", "answer_start": 454}
{"document_id": 75729, "context": "Ti3C2Tx-based materials have been widely reported as anode materials for supercapacitors and hybrid supercapacitors with the acid electrolyte. Here, the modified Ti3C2Tx MXene (400-KOH-Ti3C2) samples were synthesized based on a previous report. The XRD pattern (Fig. 1a and S1\u2020) reveals that the diffraction peaks of 400-KOH-Ti3C2 shift to a lower 2\u03b8 angle compared with those of the original Ti3C2Tx, indicating the increase of interlayer distances after KOH treatment and calcination. In addition, the intensity of partial diffraction peaks for 400-KOH-Ti3C2 is slightly weaker than that of original Ti3C2Tx, suggesting that some feature of the Ti3C2Tx diffraction peaks is shielded by the K+ intercalation into the Ti3C2 MXene layer. Raman spectroscopy (Fig. 1b) and XPS tests (Fig. S2\u2020) were carried out to further manifest the purity and chemical composition of the as-obtained 400-KOH-Ti3C2 samples. To clearly reflect the interlayer spacing for 400-KOH-Ti3C2 samples, the SEM and TEM images are given in Fig. S3\u2020 and 1c, respectively. It can be found that 400-KOH-Ti3C2 consisted of stacked MXene nanosheets. The corresponding HRTEM image shows that the interlayer distance of 400-KOH-Ti3C2 is 1.17 nm (Fig. 1d), much larger than that of the original Ti3C2Tx (0.98 nm, Fig. S4\u2020), further confirming the expansion of the interlayer distance after KOH treatment and calcination. In addition, the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) mapping images of 400-KOH-Ti3C2 clearly indicate that Ti, C, O, F and K elements are homogeneously distributed in all MXene sheets (Fig. S5\u2020).", "question": "What's the anode?", "answer": "Ti3C2Tx-based materials", "answer_start": 0}
{"document_id": 75735, "context": "The M2+\u2013Fe LDHs (M = Ni, Zn) nanosheets were prepared using a facile electrosynthesis method. Typically, nickel foam (NF, 10 \u00d7 30 \u00d7 0.05 mm3) was sonicated in 2 M HCl solution for 15 min and subsequently rinsed with water and ethanol to ensure a clean surface. The electrodeposition was carried out in a standard three-electrode system cell containing NF as the working electrode, Pt plate as the counter electrode and Ag/AgCl (3 M KCl) as the reference electrode. The electrolyte for the electrosynthesis of NiFe LDH contained Ni(NO3)2\u00b76H2O (0.03 M) and Fe(NO3)3\u00b79H2O (0.01 M). The total cation concentration in the electrolyte was maintained at 0.04 M. The potentiostatic deposition was then carried out at \u22121.0 V vs. Ag/AgCl for 300 s at room temperature. The obtained NiFe LDH nanosheets were carefully withdrawn and rinsed thoroughly with water and ethanol and left to dry at 45 \u00b0C. The NiZnFe LDHs nanosheets were prepared via a similar method, by replacing Ni(NO3)2\u00b76H2O (0.03 M) with a mixture of Ni(NO3)2\u00b76H2O (0.027 M) and Zn(NO3)2\u00b76H2O (0.003 M).", "question": "What's the electrolyte?", "answer": "Ni(NO3)2\u00b76H2O (0.03 M) and Fe(NO3)3\u00b79H2O (0.01 M)", "answer_start": 528}
{"document_id": 75738, "context": "EELS spectra are obtained from the thin edge of cycled LLOs as labelled by the orange lines in Fig. 4(a and d) to study oxygen vacancies and TM valence states. Detailed comparisons of O-K, Ni-L, Co-L and Mn-L spectra are presented in Fig. 4(g\u2013j) and S7.\u2020 For O-K edges, the intensity of the prepeak (\u223c530 eV) is sensitive to the valence states of TM ions. The intensity of this prepeak decreases drastically from the interior of the particle to the surface and almost disappears at the surface of the cycled LLOs at the cut-off of 4.8 V (Fig. S7\u2020), indicating a significant decrease of TM valence states. This matches well with the fine changes of Mn-L edges in Fig. 4(h), which show a chemical shift (\u223c2.5 eV) toward the lower binding energy on the surface (0\u201310 nm depth), as compared with the cycled bulk (\u226530 nm depth). These signatures demonstrate that the majority of Mn ions start to shift to a lower valence at a depth of 20 nm beneath the surface of cycled LLOs at the cut-off of 4.8 V, while for the LLOs cycled at 4.5 V, the reduced valence of dominant Mn ions occurs in the top 10 nm layer beneath the surface (Fig. 4(j)). The valence decrease of Mn ions in LLOs is usually accompanied by Mn dissolution into the electrolyte during cycling, which is measured by ICP-OES as shown in Fig. S8.\u2020 The Mn concentration dissolved in the electrolyte at the cut-off of 4.8 V after 100 and 200 cycles reaches 139 and 267 ppm, respectively, which are much higher than the 56 and 97 ppm at 4.5 V. These results confirm the reduced Mn dissolution into the electrolyte for the LLOs cycled at the low cut-off of 4.5 V.", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75740, "context": "For the first cycle in LP30 a more apparent \u201cpitting\u201d peak is observed that occurs at an earlier time compared to LP30 + FEC (occurring at \u223c78% and \u223c92% capacity, respectively for 0.5 mA cm\u22122). Other studies have suggested that this is due to inhomogeneous dissolution of the lithium whiskers that result in dead Li formation and early peaking behaviour. However, the lower plating efficiency quantified with in situ NMR can also lead to the early peaking behaviour observed when lower amounts of microstructures are present. With 1 and 2 mA cm\u22122, the peaking in the first cycle (where the stripping current is kept at 1 mA cm\u22122) occurs at 85% and 89% capacity respectively. This correlates well with the in situ NMR, which indicated higher plating efficiencies for the higher current densities in LP30. The voltage traces are flatter for the LP30 + FEC electrolyte, as compared to those for LP30, consistent with both the higher plating efficiency seen in the in situ NMR and of studies showing minuscule dead lithium formation in LP30 + FEC. The lower overpotential observed for LP30 + FEC is somewhat consistent between cells (Fig. S2\u2013S4\u2020), but the overpotential is affected both by the resistances in the cell (in particular of the SEI) and the surface area (which increases during electrodeposition) accounting for variations between cells.", "question": "What's the electrolyte?", "answer": "LP30 + FEC", "answer_start": 843}
{"document_id": 75745, "context": "(2) A Ti metal precursor is anodized in an alkali electrolyte (e.g. NaOH and Ba(OH)2 solutions). The alkaline anodization (Fig. 6B) could be considered an electro-assisted hydrothermal-like process with 2 stages where TiO2\u00b72H2O anodized from the titanium anode reacts with the hot alkaline surroundings generated by a continuous electric field. In the first stage, a fast anodic reaction on the titanium surface creates a thin TiO2\u00b72H2O nanosheet layer (eqn (1) and (2)) which would react with alkali to form titanate nanowire bundles on the titanium anode (eqn (3)). In particular, it should be mentioned that the OH\u2212 concentration should be above 4 M to ensure the formation of titanate rather than titania. In the second stage, the anodized TiO2\u00b72H2O would also break down and disperse into the electrolyte to form a 3D hierarchical porous structure with a large specific surface area.", "question": "What's the anode?", "answer": " titanium ", "answer_start": 245}
{"document_id": 75745, "context": "(2) A Ti metal precursor is anodized in an alkali electrolyte (e.g. NaOH and Ba(OH)2 solutions). The alkaline anodization (Fig. 6B) could be considered an electro-assisted hydrothermal-like process with 2 stages where TiO2\u00b72H2O anodized from the titanium anode reacts with the hot alkaline surroundings generated by a continuous electric field. In the first stage, a fast anodic reaction on the titanium surface creates a thin TiO2\u00b72H2O nanosheet layer (eqn (1) and (2)) which would react with alkali to form titanate nanowire bundles on the titanium anode (eqn (3)). In particular, it should be mentioned that the OH\u2212 concentration should be above 4 M to ensure the formation of titanate rather than titania. In the second stage, the anodized TiO2\u00b72H2O would also break down and disperse into the electrolyte to form a 3D hierarchical porous structure with a large specific surface area.", "question": "What's the electrolyte?", "answer": "alkali ", "answer_start": 43}
{"document_id": 75745, "context": "(2) A Ti metal precursor is anodized in an alkali electrolyte (e.g. NaOH and Ba(OH)2 solutions). The alkaline anodization (Fig. 6B) could be considered an electro-assisted hydrothermal-like process with 2 stages where TiO2\u00b72H2O anodized from the titanium anode reacts with the hot alkaline surroundings generated by a continuous electric field. In the first stage, a fast anodic reaction on the titanium surface creates a thin TiO2\u00b72H2O nanosheet layer (eqn (1) and (2)) which would react with alkali to form titanate nanowire bundles on the titanium anode (eqn (3)). In particular, it should be mentioned that the OH\u2212 concentration should be above 4 M to ensure the formation of titanate rather than titania. In the second stage, the anodized TiO2\u00b72H2O would also break down and disperse into the electrolyte to form a 3D hierarchical porous structure with a large specific surface area.", "question": "What's the anode?", "answer": "titanium", "answer_start": 542}
{"document_id": 75745, "context": "(2) A Ti metal precursor is anodized in an alkali electrolyte (e.g. NaOH and Ba(OH)2 solutions). The alkaline anodization (Fig. 6B) could be considered an electro-assisted hydrothermal-like process with 2 stages where TiO2\u00b72H2O anodized from the titanium anode reacts with the hot alkaline surroundings generated by a continuous electric field. In the first stage, a fast anodic reaction on the titanium surface creates a thin TiO2\u00b72H2O nanosheet layer (eqn (1) and (2)) which would react with alkali to form titanate nanowire bundles on the titanium anode (eqn (3)). In particular, it should be mentioned that the OH\u2212 concentration should be above 4 M to ensure the formation of titanate rather than titania. In the second stage, the anodized TiO2\u00b72H2O would also break down and disperse into the electrolyte to form a 3D hierarchical porous structure with a large specific surface area.", "question": "What's the electrolyte?", "answer": "(e.g. NaOH and Ba(OH)2 solutions)", "answer_start": 62}
{"document_id": 75746, "context": "According to the simulation, the number of moles per surface area formed in the two electrolytes, NSEI (Fig. S17a\u2020) is also greater for the LP30 + FEC electrolyte, indicating a thicker SEI is being formed. We have estimated the thickness of the SEI by using eqn (13) and assuming it to be pure Li2CO3 so as to provide a qualitative understanding of the extent of SEI formation. Averaging over the whole experiment (74 hours) the SEI formation rate is 6.1 nm h\u22121 in LP30 and 12 nm h\u22121 for LP30 + FEC. The values are relatively large and seem to overestimate the thickness of the SEI but are on a similar scale to what was estimated in an earlier isotope exchange study (14 nm h\u22121 in LP30). One possible reason for this overestimation of thickness is the assumption that all of the reduced electrolyte species are deposited to form the SEI. However, it has been shown experimentally that a wide range of the reduced electrolyte species are soluble and go into the electrolyte. We also note that the comparison of SEI thicknesses needs to be interpreted with caution as the chemical composition and density is expected to differ between the two electrolytes.", "question": "What's the electrolyte?", "answer": "LP30 + FEC", "answer_start": 140}
{"document_id": 75747, "context": "Next, the annealed WO3\u2212x film was assembled into an electrochromic device to test its functionality. The device structure is shown in Fig. 3a, in which the FTO glass is used as the transparent electrode. The electrolyte with 1.25 M LiClO4 in a mixed solvent was used in the electrochromic device to achieve the insertion and extraction of Li+ ions in the WO3\u2212x film. The device in the bleached state shows a high transmittance in both the visible and infrared wavelength range (Fig. 3b), while in the colored state, the transmittance of the electrochromic device decreases significantly. At the wavelength of 680 nm, the transmittance difference between the two curves is around 70%. In the wavelength range of 700\u20131000 nm, the transmittance of the colored state is even less than 3%, indicating the excellent near infrared light shielding ability. Hence, in the scorching summer, smart windows made of this electrochromic WO3\u2212x film can keep the room cool by blocking heat radiation. Fig. 3c shows the photographs of the packaged electrochromic device in the coloring and bleaching process. A series of different color states from light to deep blue can be easily obtained by adjusting the applied bias from \u22123.5 V to 3.5 V, which may have potential applications in the field of electrochromic displays.", "question": "What's the electrolyte?", "answer": "1.25 M LiClO4", "answer_start": 225}
{"document_id": 75748, "context": "Intermetallic Mg2Sn alloyed with extra Mg was presented as a new high-performance anode for MIBs. The 3Mg/Mg2Sn was composed of c-Mg, a-Mg, and Mg2Sn, and showed excellent electrochemical performance when cycled in Mg(HMDS)2:MgCl2/THF. During the 1st de-magnesiation, 3Mg/Mg2Sn first dissolved Mg2+ from c-Mg, which was then followed by the complete conversion of Mg2Sn to Sn with a partial release of a-Mg. The irreversible dissolution of c-Mg facilitated the reversible de-magnesiation/magnesiation in Mg2Sn and a-Mg, and allowed 3Mg/Mg2Sn to demonstrate unprecedented electrochemical properties. Thanks to the high surface area and pore volume ascribed to the irreversible dissolution of c-Mg, the 3Mg/Mg2Sn anode delivered reversible capacities of 805 and 430 mA h g\u22121 at 100 and 1500 mA g\u22121, respectively, with reasonable cycling stability. De-magnesiated 3Mg/Mg2Sn also showed similar electrochemical performance in other conventional electrolyte systems (Mg(TFSI)2:MgCl2/diglyme and Mg(TFSI)2/acetonitrile). In addition to the beneficial role of c-Mg with respect to the electrochemical properties of 3Mg/Mg2Sn in a half-cell configuration, irreversibly dissolved Mg2+ ions could ideally balance the Mg2+ ions trapped in a Mo6S8 cathode in a full-cell.", "question": "What's the cathode?", "answer": "Mo6S8 ", "answer_start": 1230}
{"document_id": 75748, "context": "Intermetallic Mg2Sn alloyed with extra Mg was presented as a new high-performance anode for MIBs. The 3Mg/Mg2Sn was composed of c-Mg, a-Mg, and Mg2Sn, and showed excellent electrochemical performance when cycled in Mg(HMDS)2:MgCl2/THF. During the 1st de-magnesiation, 3Mg/Mg2Sn first dissolved Mg2+ from c-Mg, which was then followed by the complete conversion of Mg2Sn to Sn with a partial release of a-Mg. The irreversible dissolution of c-Mg facilitated the reversible de-magnesiation/magnesiation in Mg2Sn and a-Mg, and allowed 3Mg/Mg2Sn to demonstrate unprecedented electrochemical properties. Thanks to the high surface area and pore volume ascribed to the irreversible dissolution of c-Mg, the 3Mg/Mg2Sn anode delivered reversible capacities of 805 and 430 mA h g\u22121 at 100 and 1500 mA g\u22121, respectively, with reasonable cycling stability. De-magnesiated 3Mg/Mg2Sn also showed similar electrochemical performance in other conventional electrolyte systems (Mg(TFSI)2:MgCl2/diglyme and Mg(TFSI)2/acetonitrile). In addition to the beneficial role of c-Mg with respect to the electrochemical properties of 3Mg/Mg2Sn in a half-cell configuration, irreversibly dissolved Mg2+ ions could ideally balance the Mg2+ ions trapped in a Mo6S8 cathode in a full-cell.", "question": "What's the anode?", "answer": "3Mg/Mg2Sn", "answer_start": 701}
{"document_id": 75748, "context": "Intermetallic Mg2Sn alloyed with extra Mg was presented as a new high-performance anode for MIBs. The 3Mg/Mg2Sn was composed of c-Mg, a-Mg, and Mg2Sn, and showed excellent electrochemical performance when cycled in Mg(HMDS)2:MgCl2/THF. During the 1st de-magnesiation, 3Mg/Mg2Sn first dissolved Mg2+ from c-Mg, which was then followed by the complete conversion of Mg2Sn to Sn with a partial release of a-Mg. The irreversible dissolution of c-Mg facilitated the reversible de-magnesiation/magnesiation in Mg2Sn and a-Mg, and allowed 3Mg/Mg2Sn to demonstrate unprecedented electrochemical properties. Thanks to the high surface area and pore volume ascribed to the irreversible dissolution of c-Mg, the 3Mg/Mg2Sn anode delivered reversible capacities of 805 and 430 mA h g\u22121 at 100 and 1500 mA g\u22121, respectively, with reasonable cycling stability. De-magnesiated 3Mg/Mg2Sn also showed similar electrochemical performance in other conventional electrolyte systems (Mg(TFSI)2:MgCl2/diglyme and Mg(TFSI)2/acetonitrile). In addition to the beneficial role of c-Mg with respect to the electrochemical properties of 3Mg/Mg2Sn in a half-cell configuration, irreversibly dissolved Mg2+ ions could ideally balance the Mg2+ ions trapped in a Mo6S8 cathode in a full-cell.", "question": "What's the electrolyte?", "answer": "Mg(TFSI)2:MgCl2/diglyme and Mg(TFSI)2/acetonitrile", "answer_start": 962}
{"document_id": 75750, "context": "A button-sized hybrid electrolyte cell (Fig. S4\u2020), in which an ionic liquid-infiltrated NCM with a LLZTO electrolyte and a 20 \u03bcm\u2013thick Li metal were respectively used as a cathode and a Li metal anode, was fabricated to check out the improvement of the electrochemical performance after laser-annealing treatment. For comparison, two kinds of LLZTO pellets were used: a polished pellet without laser treatment and a laser-treated pellet. In Fig. 6a and b, the Nyquist plots of the AC-impedance spectra from the samples obtained at an open circuit from the cells were compared. As shown in Fig. 6a and b, the ohmic losses calculated from the high-frequency intercept with the real axis were almost the same in the range of 3.2\u20134.0 \u03a9 cm2 for both the cells. Based on the ohmic resistance, the ionic conductivities were expected to be in the range of 7.5\u20139.4 10\u22123 S cm\u22121 at 60 \u00b0C for the LLZTO pellets with and without laser treatment. These conductivity values are consistent with the reported values of Ta-doped LLZO and also with that value (\u223c8.6 \u00d7 10\u22123 S cm\u22121 at 60 \u00b0C) experimentally obtained from the Au-sputtered symmetric cells (Au/LLZTO/Au), as shown in Fig. S5a.\u2020 Thus, it can be inferred that the cathode and ionic liquid catholyte are not contributing significantly to the ohmic losses in these cells. Furthermore, the amorphous layer formed by laser irradiation had no significant effect on the ohmic resistance due to its low thickness of about 400 nm. The AC-impedance spectra of both cells consist of a depressed arc in the high-frequency range, a narrow line inclined at a constant angle to the real axis (Warburg impedance), and a capacitive line (blocking region) in the low-frequency range, which are typical features of a NCM-Li cell. The high-frequency arc could be associated with the charge-transfer reactions at the cathode and anode interface. Because the relaxation times for the cathodic and anodic reactions are generally overlapped over the high-frequency ranges for a NCM-Li full cell, it is difficult to separate the charge-transfer resistance at the Li-LLZTO interface from the resistance at the NCM-ionic liquid. The AC-impedance spectrum for Li/LLZTO/Li cell is also shown in Fig. S5b.\u2020 Considering that the electrochemical kinetics at the cathode would be almost the same for both cells, the variation in the high-frequency arc could be attributed to the charge-transfer resistance at the Li metal and LLZTO interface. The values of the overall interfacial resistance, Rct, were quantitatively determined from complex non-linear least-square (CNLS) fitting of the measured impedance spectra based on a typical equivalent circuit of the NCM-Li full cell. The Rct (Rc + Ra) value was reduced from \u223c80 \u03a9 cm2 to \u223c26 \u03a9 cm2 when the LLZTO surface was treated by a laser beam. In addition, as shown in Fig. S5c,\u2020 the electronic conductivity of LLZTO was significantly reduced by the laser treatment, which can originate from the formation of a wide band gap surface layer.", "question": "What's the cathode?", "answer": "NCM", "answer_start": 88}
{"document_id": 75750, "context": "A button-sized hybrid electrolyte cell (Fig. S4\u2020), in which an ionic liquid-infiltrated NCM with a LLZTO electrolyte and a 20 \u03bcm\u2013thick Li metal were respectively used as a cathode and a Li metal anode, was fabricated to check out the improvement of the electrochemical performance after laser-annealing treatment. For comparison, two kinds of LLZTO pellets were used: a polished pellet without laser treatment and a laser-treated pellet. In Fig. 6a and b, the Nyquist plots of the AC-impedance spectra from the samples obtained at an open circuit from the cells were compared. As shown in Fig. 6a and b, the ohmic losses calculated from the high-frequency intercept with the real axis were almost the same in the range of 3.2\u20134.0 \u03a9 cm2 for both the cells. Based on the ohmic resistance, the ionic conductivities were expected to be in the range of 7.5\u20139.4 10\u22123 S cm\u22121 at 60 \u00b0C for the LLZTO pellets with and without laser treatment. These conductivity values are consistent with the reported values of Ta-doped LLZO and also with that value (\u223c8.6 \u00d7 10\u22123 S cm\u22121 at 60 \u00b0C) experimentally obtained from the Au-sputtered symmetric cells (Au/LLZTO/Au), as shown in Fig. S5a.\u2020 Thus, it can be inferred that the cathode and ionic liquid catholyte are not contributing significantly to the ohmic losses in these cells. Furthermore, the amorphous layer formed by laser irradiation had no significant effect on the ohmic resistance due to its low thickness of about 400 nm. The AC-impedance spectra of both cells consist of a depressed arc in the high-frequency range, a narrow line inclined at a constant angle to the real axis (Warburg impedance), and a capacitive line (blocking region) in the low-frequency range, which are typical features of a NCM-Li cell. The high-frequency arc could be associated with the charge-transfer reactions at the cathode and anode interface. Because the relaxation times for the cathodic and anodic reactions are generally overlapped over the high-frequency ranges for a NCM-Li full cell, it is difficult to separate the charge-transfer resistance at the Li-LLZTO interface from the resistance at the NCM-ionic liquid. The AC-impedance spectrum for Li/LLZTO/Li cell is also shown in Fig. S5b.\u2020 Considering that the electrochemical kinetics at the cathode would be almost the same for both cells, the variation in the high-frequency arc could be attributed to the charge-transfer resistance at the Li metal and LLZTO interface. The values of the overall interfacial resistance, Rct, were quantitatively determined from complex non-linear least-square (CNLS) fitting of the measured impedance spectra based on a typical equivalent circuit of the NCM-Li full cell. The Rct (Rc + Ra) value was reduced from \u223c80 \u03a9 cm2 to \u223c26 \u03a9 cm2 when the LLZTO surface was treated by a laser beam. In addition, as shown in Fig. S5c,\u2020 the electronic conductivity of LLZTO was significantly reduced by the laser treatment, which can originate from the formation of a wide band gap surface layer.", "question": "What's the anode?", "answer": " Li metal", "answer_start": 185}
{"document_id": 75750, "context": "A button-sized hybrid electrolyte cell (Fig. S4\u2020), in which an ionic liquid-infiltrated NCM with a LLZTO electrolyte and a 20 \u03bcm\u2013thick Li metal were respectively used as a cathode and a Li metal anode, was fabricated to check out the improvement of the electrochemical performance after laser-annealing treatment. For comparison, two kinds of LLZTO pellets were used: a polished pellet without laser treatment and a laser-treated pellet. In Fig. 6a and b, the Nyquist plots of the AC-impedance spectra from the samples obtained at an open circuit from the cells were compared. As shown in Fig. 6a and b, the ohmic losses calculated from the high-frequency intercept with the real axis were almost the same in the range of 3.2\u20134.0 \u03a9 cm2 for both the cells. Based on the ohmic resistance, the ionic conductivities were expected to be in the range of 7.5\u20139.4 10\u22123 S cm\u22121 at 60 \u00b0C for the LLZTO pellets with and without laser treatment. These conductivity values are consistent with the reported values of Ta-doped LLZO and also with that value (\u223c8.6 \u00d7 10\u22123 S cm\u22121 at 60 \u00b0C) experimentally obtained from the Au-sputtered symmetric cells (Au/LLZTO/Au), as shown in Fig. S5a.\u2020 Thus, it can be inferred that the cathode and ionic liquid catholyte are not contributing significantly to the ohmic losses in these cells. Furthermore, the amorphous layer formed by laser irradiation had no significant effect on the ohmic resistance due to its low thickness of about 400 nm. The AC-impedance spectra of both cells consist of a depressed arc in the high-frequency range, a narrow line inclined at a constant angle to the real axis (Warburg impedance), and a capacitive line (blocking region) in the low-frequency range, which are typical features of a NCM-Li cell. The high-frequency arc could be associated with the charge-transfer reactions at the cathode and anode interface. Because the relaxation times for the cathodic and anodic reactions are generally overlapped over the high-frequency ranges for a NCM-Li full cell, it is difficult to separate the charge-transfer resistance at the Li-LLZTO interface from the resistance at the NCM-ionic liquid. The AC-impedance spectrum for Li/LLZTO/Li cell is also shown in Fig. S5b.\u2020 Considering that the electrochemical kinetics at the cathode would be almost the same for both cells, the variation in the high-frequency arc could be attributed to the charge-transfer resistance at the Li metal and LLZTO interface. The values of the overall interfacial resistance, Rct, were quantitatively determined from complex non-linear least-square (CNLS) fitting of the measured impedance spectra based on a typical equivalent circuit of the NCM-Li full cell. The Rct (Rc + Ra) value was reduced from \u223c80 \u03a9 cm2 to \u223c26 \u03a9 cm2 when the LLZTO surface was treated by a laser beam. In addition, as shown in Fig. S5c,\u2020 the electronic conductivity of LLZTO was significantly reduced by the laser treatment, which can originate from the formation of a wide band gap surface layer.", "question": "What's the electrolyte?", "answer": "LLZTO ", "answer_start": 99}
{"document_id": 75750, "context": "A button-sized hybrid electrolyte cell (Fig. S4\u2020), in which an ionic liquid-infiltrated NCM with a LLZTO electrolyte and a 20 \u03bcm\u2013thick Li metal were respectively used as a cathode and a Li metal anode, was fabricated to check out the improvement of the electrochemical performance after laser-annealing treatment. For comparison, two kinds of LLZTO pellets were used: a polished pellet without laser treatment and a laser-treated pellet. In Fig. 6a and b, the Nyquist plots of the AC-impedance spectra from the samples obtained at an open circuit from the cells were compared. As shown in Fig. 6a and b, the ohmic losses calculated from the high-frequency intercept with the real axis were almost the same in the range of 3.2\u20134.0 \u03a9 cm2 for both the cells. Based on the ohmic resistance, the ionic conductivities were expected to be in the range of 7.5\u20139.4 10\u22123 S cm\u22121 at 60 \u00b0C for the LLZTO pellets with and without laser treatment. These conductivity values are consistent with the reported values of Ta-doped LLZO and also with that value (\u223c8.6 \u00d7 10\u22123 S cm\u22121 at 60 \u00b0C) experimentally obtained from the Au-sputtered symmetric cells (Au/LLZTO/Au), as shown in Fig. S5a.\u2020 Thus, it can be inferred that the cathode and ionic liquid catholyte are not contributing significantly to the ohmic losses in these cells. Furthermore, the amorphous layer formed by laser irradiation had no significant effect on the ohmic resistance due to its low thickness of about 400 nm. The AC-impedance spectra of both cells consist of a depressed arc in the high-frequency range, a narrow line inclined at a constant angle to the real axis (Warburg impedance), and a capacitive line (blocking region) in the low-frequency range, which are typical features of a NCM-Li cell. The high-frequency arc could be associated with the charge-transfer reactions at the cathode and anode interface. Because the relaxation times for the cathodic and anodic reactions are generally overlapped over the high-frequency ranges for a NCM-Li full cell, it is difficult to separate the charge-transfer resistance at the Li-LLZTO interface from the resistance at the NCM-ionic liquid. The AC-impedance spectrum for Li/LLZTO/Li cell is also shown in Fig. S5b.\u2020 Considering that the electrochemical kinetics at the cathode would be almost the same for both cells, the variation in the high-frequency arc could be attributed to the charge-transfer resistance at the Li metal and LLZTO interface. The values of the overall interfacial resistance, Rct, were quantitatively determined from complex non-linear least-square (CNLS) fitting of the measured impedance spectra based on a typical equivalent circuit of the NCM-Li full cell. The Rct (Rc + Ra) value was reduced from \u223c80 \u03a9 cm2 to \u223c26 \u03a9 cm2 when the LLZTO surface was treated by a laser beam. In addition, as shown in Fig. S5c,\u2020 the electronic conductivity of LLZTO was significantly reduced by the laser treatment, which can originate from the formation of a wide band gap surface layer.", "question": "What's the cathode?", "answer": "", "answer_start": 0}
{"document_id": 75751, "context": "Prior to its integration with the electrodes, various properties of the LLZO SE such as the microstructure, crystalline phase and ionic conductivity were characterized. To improve the Li ion conductivity in the parent LLZO structures, Nb5+ was doped at the Zr4+ sites to create Li+ vacancies, and Ba2+ was doped at the La3+ sites to increase the Li+ concentration.Fig. 1a shows the cross-sectional SEM image of the LLZO SE pellet. A dense microstructure was formed by the uniaxial pressing and the subsequent sintering steps. The relative density of the LLZO pellet was \u223c95% which was the ratio of the theoretical density calculated using the lattice parameter derived from XRD and the real density measured using a He gas pycnometer. XRD analysis of the LLZO SE (Fig. 1b) reveals the cubic phase of LLZO, where most of the diffraction peaks relate to the parent Li\u2013garnet phase \u201cLi5La3Nb2O12\u201d with the space group Iad. A small peak at \u223c2\u03b8 = 30 degree corresponds to the presence of BaZrO3 impurities. LLZO exists in cubic and tetragonal polymorphs. The former is typically obtained at higher sintering temperatures (>1000 \u00b0C), and exhibits about two orders of magnitude higher Li-ion conduction.Fig. 1c shows the Nyquist plots of a Au|LLZO|Au quasi-blocking cell obtained at room temperature. Au metal was sputtered on either side of the LLZO pellet to obtain uniform contacts. The plots were fitted with a resistor\u2013capacitor (constant phase element) circuit and a series capacitor. By fitting the high frequency (5\u20130.5 MHz) semi-circle, we obtain a capacitance of \u223c2.7 \u00d7 10\u221210 F which could be attributed to the bulk and grain-boundary contributions to Li+ transport in the SE. In the low frequency range (<100 Hz), we observe a linear increase which reflects the quasi-blocking effect of the Au electrodes. From the low-frequency intercept of the semi-circle with the x-axis we determine a bulk resistance (RB) of \u223c640 \u00b1 1.4 \u03a9 cm2. When using l as the thickness of the SE pellet and a as the electrode surface area, the ionic conductivity \u03c3 was calculated using the formula: \u03c3 = l/RBa, which was found to be \u223c1.5 \u00d7 10\u22124 S cm\u22121. Further, \u03c3 is plotted as a function of increasing temperature T in Fig. 1d and the relationship follows an Arrhenius behavior as expressed by the following equation where \u03c3 is the conductivity of the electrolyte (S cm\u22121), A is the pre-exponential factor, T is the temperature (Kelvin), Ea is the activation energy expressed (eV), and kb is Boltzmann's constant. The activation energy Ea calculated from the Arrhenius plot is 0.35 eV, which is consistent with values reported in the literature. The EIS plots used to measure Ea are given in Fig. S1.\u2020", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}
{"document_id": 75754, "context": "Bulk electrolysis was conducted to test the performance of CRLEs under conditions of electrochemical turnover. A series of charge/discharge experiments was performed for the negative and the positive electrolyte separately. The coulombic efficiency (CE) was calculated from photometric and coulometric data according to eqn (5), where npt are the number of moles obtained with photometry (c is the concentration, V is the volume, and 0.8 is the SoC difference), and nec the number of moles calculated from Faraday's law (I is the current, t is the time and F is the Faraday's constant).", "question": "What's the electrolyte?", "answer": "", "answer_start": 0}