milerssliu/battery-device-data-qa huggingface dataset:
qas: question: What's the cathode?
answers: answer_id: 81168
question_id: 66158
text: nanomesh 
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−3 and 5387 mA cm−3, respectively). For each C-rate, five discharge–charge cycles were recorded, starting from the fully charged state. Therefore, we distinguish the “initial” discharge capacities (recorded after fully charging the cathode at 4.0 V for 1 hour) from the “continuous” discharge capacities recorded in the four consecutive cycles, which also depend on the charging kinetics at each C-rate. The discharge–charge profiles recorded in the first discharge–charge 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 ∼3 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. (∼55% 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).
qas: question: What's the cathode?
answers: answer_id: 81335
question_id: 66158
text: DBHF nanofibers
question: What's the cathode?
answers: answer_id: 81337
question_id: 66161
text: DBHF
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–air modes, but also opens a new avenue to fabricate high-performance flexible batteries for different electronics under various working conditions.
qas: question: What's the cathode?
answers: answer_id: 81340
question_id: 66158
text:  lithium polysulfides (LiPSs) 
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–sulfur (Li–S) 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–S 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 (∼80%) 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 “shuttle effect” and anode corrosion. These issues have been the bottlenecks in the development of high-performance Li–S batteries.
qas: question: What's the cathode?
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−3, 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.
qas: question: What's the cathode?
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 μL of the gel electrolytes were introduced at each interface. Cells without the interlayer were heated till 180 °C (melting temperature of Li) to promote Li–SE mutual contact. Both Au|LLZO|Au and Li|LLZO|Li were assembled in Swagelok©-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−2. 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 °C for 24 h. The sulfur loading at the electrode was ∼0.5 mgsulfur cm−2. The electrochemical performance of the full cells was tested by galvanostatic cycling with 0.1C (1C = 1672 mA gsulfur−1) 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.
qas: question: What's the cathode?
answers: answer_id: 81355
question_id: 66158
text: LiNiO2 
question: What's the cathode?
answers: answer_id: 81357
question_id: 66161
text: Ni-rich oxide
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.
qas: question: What's the cathode?
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†). 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.
qas: question: What's the cathode?
answers: answer_id: 81366
question_id: 66158
text:  LiCoO2 (LCO) 
question: What's the cathode?
answers: answer_id: 81367
question_id: 66161
text: LCO
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−2. Subsequently, on the LTO anode (thickness = 50 μm and mass loading = 5.9 mg cm−2), a composite polymer electrolyte (CPE, gel electrolyte precursor/Al2O3 nanoparticles (average particle size ∼300 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 μm and mass loading = 6.2 mg cm−2). 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.
qas: question: What's the cathode?
answers: answer_id: 81372
question_id: 66158
text: Mg0.23V2O5·1.0H2O
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)–polyacrylamide (PAM) hydrogel electrolyte and a Mg0.23V2O5·1.0H2O cathode. The designed CNF–PAM hydrogel shows high stretchability and robust mechanical stability. Moreover, the porous CNF–PAM hydrogel electrolyte provides efficient pathways for the transportation of zinc ions. And the robust layered structure of V2O5·1.0H2O 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−1 (charging time of around 3 minutes), the ssZIBs can deliver a high reversible capacity of 216 mA h g−1 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.
qas: question: What's the cathode?
answers: answer_id: 81401
question_id: 66158
text: O3-type layered oxide
question: What's the cathode?
answers: answer_id: 81402
question_id: 66161
text: O3/P3-Nax[Ni0.5Mn0.5]O2
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–P3 phase transformation during the Na+ extraction/insertion process. Various Na/vacancy configurations on O3-Nax[Ni0.5Mn0.5]O2 compositions (0 ≤ x ≤ 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–P3 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–P3 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–P3 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 ∼4.11 V (vs. Na+/Na) and more than ∼2.48 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–P3 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 ≤ x ≤ 1) with experimentally measured galvanostatic intermittent titration technique (GITT) profiles in the voltage range of 2.0–4.3 V. To confirm our hypothesis that the Ca-substituted cathode would undergo a similar O3–P3 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 2.0–4.3 V; this clearly verified our hypothesis and confirmed that ∼1.0 mol of Na+ ions could be extracted/inserted from/into Na0.98Ca0.01[Ni0.5Mn0.5]O2.
qas: question: What's the cathode?
answers: answer_id: 81399
question_id: 66158
text:  platinum wire or foil
question: What's the anode?
answers: answer_id: 81398
question_id: 66159
text:  bulk antimony, bismuth and their compounds
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− 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 −5 V, the SO42− 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).
qas: question: What's the cathode?
answers: answer_id: 81394
question_id: 66158
text: Co5.47Nx
question: What's the cathode?
answers: answer_id: 81395
question_id: 66161
text: Co5.47N
context: The development of high-capacity rechargeable lithium–sulfur 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–C) spheres with nitrogen vacancies are developed as a high-performance cathode material for use in lithium–sulfur batteries. Nitrogen vacancies are formed by annealing a zeolite imidazole framework (ZIF-67) precursor in ammonia. Benefiting from its Co–N bonds and nitrogen-vacancy sites, the Co5.47Nx–C 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–C electrode delivers a capacity of 850 mA h g−1 at 0.5C and a rate performance of 320 mA h g−1 at 10C. This high-performance, high-rate lithium–sulfur battery is promising for widespread application in electric vehicles and intelligent devices.
qas: question: What's the cathode?
answers: answer_id: 81400
question_id: 66158
text: MWCNTs
context: The carefully designed combination of TM-ions and non-TM-ions suppressed the occurrences of phase transformations during electrochemical cycling in Na ‘half’ 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 ∼140 mA h g−1 (within 2.0–4.0 V, at C/5), negligible voltage hysteresis and a capacity retention of ∼80% 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 ∼87% after 100 cycles and ∼75% after 200 cycles, along with bestowing excellent rate capability, viz., capacities at 2C and 5C being ∼65% and ∼50% of capacity at C/10, respectively.
qas: question: What's the cathode?
answers: answer_id: 84077
question_id: 66158
text: Layer structured sodium transition metal oxides
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.