batterydata/battery-device-data-qa huggingface dataset:
Then Li–O2 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†) 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−1 with the capacity limited at 1000 mA h g−1. 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†). 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 μm thickness of the protective film covered on the Li surface (Fig. S13b and d†). LOBs with different SEI thicknesses were assembled and tested. As shown in Fig. S14,† 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,† 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

Question: What's the anode?
Answer:  Li

Question: What's the cathode?
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–bQSSB. 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)

Question: What's the anode?
Answer:  Li4Ti5O12 (LTO)
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?

Question: What's the anode?
Answer: Zn metal

Question: What's the electrolyte?

Question: What's the anode?
Answer: Zn metal
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

Question: What's the anode?
Answer: hard carbon

Question: What's the electrolyte?
Answer: BaTiO3-P(VDF-HFP)-NaClO4
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−2 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

Question: What's the cathode?
Answer: CoFe@NCNT/CFC
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 °C. 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.† 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−1 at 0.3C and 55 °C, respectively. Fig. S3b† 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 °C. The discharge capacity of bare LMO sharply fades to 11 mA h gLMO−1 (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−1 after 100 cycles at 55 °C 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 °C and 0.3C is depicted in Fig. S3c.† The above results indicate that LMO-30 min demonstrates better cycling performance at 55 °C 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 °C as seen in Fig. 2b. The effect of coating on capacity retention at 25 °C and 55 °C 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

Question: What's the electrolyte?
Answer: LMO

Question: What's the cathode?
Answer: PLMO coated
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−2. 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?

Question: What's the anode?
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†). Both cathodes underwent a series of phase transitions (O3hex. → O′3mon. → P3hex. → P′3mon. → → ). The intensity of the redox peaks of the Na[Ni0.5Mn0.5]O2 cathode, especially during the hexagonal O3′–hexagonal O3′′ 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†) to examine the oxidation state of transition metals during the charge–discharge 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,† 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

Question: What's the cathode?
Answer: Na0.98Ca0.01[Ni0.5Mn0.5]O2
As the key component in HZBs, cathodes work as the electroactive materials in rechargeable Zn-ion batteries and the catalyst in Zn–air 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–Co3O4/air hybrid battery. Wang et al. constructed NiCo2S4 nanotubes on an N-doped carbon network derived from filter paper and fabricated a Zn–NiCo2S4/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–Ag/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

Question: What's the cathode?
Answer: Ni3S2 nanosheets on Ni foam
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–electrolyte interphase (CEI). The film thickness is optimized taking into account the electrospinning–processing 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 °C) and elevated temperature (55 °C). The PVDF@LGLZNO fibrous film coating suppresses the dissolution of manganese both at high C-rates and 55 °C, 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–electrolyte 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)

Question: What's the anode?
Answer:  S-C(PAN)
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‖MoP@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−2, urea–water 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−2. 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‖MoP/NF, NiCo-LDH/NF‖NiCo-LDH/NF, MoP@NiCo-LDH/NF-20‖MoP@NiCo-LDH/NF-20, and Pt/C/NF‖IrO2/NF electrolysis cells in 1 M KOH with 0.5 M urea. At 100 mA cm−2, the cell voltages of MoP/NF‖MoP/NF, NiCo-LDH/NF‖NiCo-LDH/NF, MoP@NiCo-LDH/NF-20‖MoP@NiCo-LDH/NF-20, and Pt/C/NF‖IrO2/NF are 1.494, 1.579, 1.405, and 1.708 V, respectively (Table S1†). The results show that at the same current density, the driving cell voltage of MoP@NiCo-LDH/NF-20‖MoP@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†).

Question: What's the cathode?
Answer:  MoP@NiCo-LDH/NF-20

Question: What's the anode?
Answer:  MoP@NiCo-LDH/NF-20
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 ∼4.55 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–graphene cell with areal capacities of ∼2.2 mA h cm−2 and ∼3 mA h cm−2, 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−2 (2C) with 100% overcharge and a maximum capacity of 7540% SOC at 0.2C.

Question: What's the cathode?
Answer: Ni-rich layered

Question: What's the cathode?
Answer: Ni-rich
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–S 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–S 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

Question: What's the anode?
Answer: Li

Question: What's the cathode?
Answer: sulfur
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 → NaV2(PO4)3 + 2Na+ + 2e−; anode: xC + 2Na+ + 2e− → 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

Question: What's the anode?
Answer: C
A superfast and stable ssZIB based on a CNF–PAM hydrogel electrolyte and a Mg0.23V2O5·1.0H2O cathode was successfully developed from this work. 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. The prepared ssZIB shows remarkably high rate capability and long-term cycling performance. At a high current density of 5 A g−1, the ssZIB provides a high specific capacity of about 216 mA h g−1 within a charging time of only three minutes for over 2000 cycles, maintaining 98.6% of the initial capacity. Furthermore, with the designed CNF–PAM 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: Mg0.23V2O5·1.0H2O

Question: What's the electrolyte?
Answer: CNF–PAM hydrogel