milerssliu/battery-device-data-qa huggingface dataset:
qas: question: What's the cathode?
answers: answer_id: 84116
question_id: 66158
text: polymeric 
question: What's the electrolyte?
answers: answer_id: 84117
question_id: 66160
text: (0.5 M KTFSI in DME:DOL)
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−1 at 20 mA g−1. A capacity fading of 25% was observed after 50 cycles, while the cyclability with a carbonate-based electrolyte was inferior.
qas: question: What's the cathode?
answers: answer_id: 84045
question_id: 66158
text:  CNFs/graphene
question: What's the anode?
answers: answer_id: 84044
question_id: 66159
text: CNFs/Nb2O5
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−1), and superior rate capability with specific capacities of 287 mA h g−1 at 0.5C and 172 mA h g−1 at 150C, which was much higher than that of pure CNFs (159.1 mA h g−1 at 0.5C and 64.9 mA h g−1 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−1, 11.2 mW h cm−3) and impressive power densities (60 kW kg−1, 5.4 W h cm−3), 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.
qas: question: What's the cathode?
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.† 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–i), 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.
qas: question: What's the cathode?
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–O 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−1, 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 −70 °C.
qas: question: What's the cathode?
answers: answer_id: 84046
question_id: 66158
text:  LiFePO4
question: What's the cathode?
answers: answer_id: 84047
question_id: 66161
text: LiFePO4
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 ≈ 0.5) crystal. Fig. 6(a–c) 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–Li 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.
qas: question: What's the cathode?
answers: answer_id: 84056
question_id: 66158
text: sodium-containing layered
question: What's the cathode?
answers: answer_id: 84057
question_id: 66161
text: oxide 
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.
qas: question: What's the cathode?
answers: answer_id: 84065
question_id: 66158
text: sulfur 
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−1. 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–S cell cathode shows a synergistic effect for LiPS fixation and utilization. Adsorption experiments indicate that NbS2 and NbS2–IG 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–IG electrode. These results suggest that NbS2 is conducive to providing access for electric charge to the NbS2–LiPS interface and synchronously triggers the redox reactions of LiPSs. Consequently, reversible capacities of 195, 107, and 74 mA h g−1 (1.05 mg cm−2) are achieved after 2000 cycles at ultrahigh rates of 20, 30, and 40C, respectively, and a high discharge capacity of 405 mA h g−1 (3.25 mg cm−2) 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–S batteries.
qas: question: What's the cathode?
answers: answer_id: 84067
question_id: 66158
text: LiFePO4 
context: The crystal structure of the current collectors was characterized using a Rigaku D/max-2200/PC X-ray diffractometer (XRD) with Cu Kα radiation (λ = 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−2 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−2 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.
qas: question: What's the cathode?
answers: answer_id: 84073
question_id: 66158
text: NMC 
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° 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° 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† 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.
qas: question: What's the cathode?
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 −40 °C at a current density of 0.1C. In addition, the Li/LiV2(PO4)3 primary battery showed great potential for all-weather applications.
qas: question: What's the cathode?
answers: answer_id: 84081
question_id: 66158
text: SiC/RGO
context: The charging process of the Li–CO2 battery was also studied systematically (Fig. 5). The Li–CO2 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–CO2 battery with the SiC/RGO cathode outperforms the majority of Li–CO2 batteries (Table S1†). Furthermore, the fast response of the charge voltage to the on–off irradiation (Fig. S10†) 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–CO2 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†), consistent with the results obtained from FTIR spectra (Fig. 5f and S8†). Overall, the light-assisted Li–CO2 battery possesses better reversibility in comparison with the conventional Li–CO2 battery, owing to the facile CO2ER process promoted by the photogenerated holes.
qas: question: What's the cathode?
answers: answer_id: 84085
question_id: 66158
text: air-cathode
question: What's the anode?
answers: answer_id: 84087
question_id: 66159
text:  Li
question: What's the cathode?
context: 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.
qas: question: What's the cathode?
answers: answer_id: 84101
question_id: 66158
text: CNF@V2S3/S 
context: Vanadium sulfides, such as VS2, have been often used as sulfur host materials for lithium–sulfur 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−1 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.
qas: question: What's the cathode?
answers: answer_id: 84102
question_id: 66158
text:  LiCoO2 (LCO)
question: What's the anode?
answers: answer_id: 84103
question_id: 66159
text:  Li4Ti5O12 (LTO)
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–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).