milerssliu/battery-device-data-qa huggingface dataset:
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 ≈100 mA h g−1 with good capacity retention. Zhao et al. synthesized AlF3-coated K1.39Mn3O6 microspheres that showed a highly reversible capacity of 110 mA h g−1 at 10 mA g−1, excellent cycling stability and rate capability. Xia et al. prepared the high K-content K0.77MnO2·0.23H2O for high-performance non-aqueous K-ion batteries with 134 mA h g−1 at a current density of 100 mA g−1.

Question: What's the cathode?
Answer: K0.5MnO2
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
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?
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–d), 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)†). For the P2-NMZ10 sample, the precipitates are quite stable once formed. As illustrated in Fig. 6(e–g), 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).† 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
A very rapid increase in separation between the ‘charge-averaged’ discharge and charge voltages, within the first few cycles (i.e., ∼10 cycles), can be observed for the ‘no’ Ti-containing Na-TM-oxide (i.e., ‘0.5 Mn/0 Ti’) (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 ‘charge-averaged’ 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 ‘0.5 Mn/0 Ti’ and ‘0 Mn/0.5 Ti’ Na-TM-oxide cathodes in the context of variations of the ‘charge-averaged’ 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 ‘control’ Na-TM-oxide cathode by ∼0.25 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: ‘0.5 Mn/0 Ti’ and ‘0 Mn/0.5 Ti’ Na-TM-oxide
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
• A high sulfur loading is essential to produce practical Li–S 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?
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 0.6–0.8 mg cm−2. The electrolyte was 1 M lithium bis (trifluoromethane) sulfonimide, LiTFSI, in dimethyl sulfoxide (DMSO). 2032-type coin LOBs, which included a lithium metal anode (Ø = 15 mm), a glass-fiber separator (GFC, Whatman, Ø = 19 mm) impregnated with an electrolyte, and a well-prepared cathode (Ø = 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–charge 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?
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 0.6–0.8 mg cm−2. The electrolyte was 1 M lithium bis (trifluoromethane) sulfonimide, LiTFSI, in dimethyl sulfoxide (DMSO). 2032-type coin LOBs, which included a lithium metal anode (Ø = 15 mm), a glass-fiber separator (GFC, Whatman, Ø = 19 mm) impregnated with an electrolyte, and a well-prepared cathode (Ø = 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–charge 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
In this review, we have provided a comprehensive overview of the design, synthesis, and application of metal sulfides in rechargeable Li–S batteries. We aimed to summarize important concepts to boost the practical development of high-energy-density Li–S 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–S 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–S batteries.

Question: What's the cathode?
Answer: sulfur
In this review, we have provided a comprehensive overview of the design, synthesis, and application of metal sulfides in rechargeable Li–S batteries. We aimed to summarize important concepts to boost the practical development of high-energy-density Li–S 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–S 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–S batteries.

Question: What's the anode?
Answer: lithium
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−1. Approximately 85% retention of the capacity over 1000 cycles (the initial capacity was 183 mA h g−1) 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−1 with obvious long-time active phenomenon (Fig. S3c†). 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,† where a lower charge-transfer resistance (Rct) can be clearly observed compared to that of NV-ACC.

Question: What's the cathode?
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†). 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†). 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
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†). 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†). 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))
However, because of the larger sodium ionic radius (rNa+ 1.02 Å vs. rLi+ 0.76 Å), 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–O covalent bond of the PO43− group, combined with the high electronegativity of the fluoride anion (F−), 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
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−3 (weight percentage of 21.1%) is obtained. And the capacity of the corresponding battery can be as high as 369.7 mA h g−1 (based on the mass of the active material of MnO2), superior to that of most of the earlier reported Zn–MnO2 batteries and aqueous zinc batteries (see Table S1†), such as Zn–MnO2 batteries (225 mA h g−1), Zn–ZnMn2O4 batteries (150 mA h g−1), Zn–PTO batteries (336 mA h g−1), Zn–NiCo2O4 batteries (183.1 mA h g−1), Zn–MoS2 batteries (202.6 mA h g−1), Ni–Zn batteries (265 mA h g−1), and Zn–V2O5@PEDOT batteries (360 mA h g−1). When the concentration of KMnO4 increases to 10 mM, the mass loading of MnO2 reaches 51.0 mg cm−3 (weight percentage of 79.1%), and the corresponding capacity remains at 306.7 mA h g−1. Meanwhile, the volumetric capacity of the battery increases accordingly at the beginning, and reaches its highest value (15.6 mA h cm−3) 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.† 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?
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?
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?
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− 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?
Areal capacities for organic-based cathodes range from ∼0.07 to ∼2 mA h cm−2 (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
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?
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?
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
Spherical [Ni0.5Mn0.5](OH)2 precursors were synthesized by the co-precipitation method. Stoichiometric amounts of NiSO4·6H2O and MnSO4·H2O (Samchun Chemical, Korea) were used as starting materials for [Ni0.5Mn0.5](OH)2. The metal solution concentration (2 mol L−1 for the metal solution), pH (∼11.0), temperature (45 °C), 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 °C 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 °C for 24 h in an oxygen atmosphere, and quenched under vacuum conditions. For Ca-substituted Na1−2xCax[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 = 1.05–2x: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