milerssliu/battery-device-data-qa huggingface dataset:
Here, we demonstrate a new method to modify the surface of an LMO electrode for the first time. A stabilized LMO cathode was achieved by the electrospun coating of PVDF and gallium (Ga) and niobium (Nb) co-doped LLZO (Li5.6Ga0.26La2.9Zr1.87Nb0.05O12, LGLZNO). The PVDF@LGLZNO fibrous film coating acts as an effective artificial CEI to suppress the manganese dissolution and significantly minimize the undesirable interfacial reaction between the cathode and electrolyte. The improved LMO was further verified by coupling with an S-C(PAN) composite anode to realize stable rate performance and long cycling stability.

Question: What's the electrolyte?
Increasing the areal sulfur loading and decreasing the amount of electrolyte in cathodes are natural methods to meet the above requirements. However, thick sulfur electrodes suffer cracking and peeling off problems during slurry casting, thus damaging the electrode integrity. Another obstacle for thick electrodes is the poor immersion of the electrolyte, which restrains the effective sulfur utilization. A promising alternate approach is to use a polysulfide solution, designated as a catholyte, as the starting material. The liquid catholyte is ready to immerse and envelope the surface of the conductive host, thus facilitating rapid charge transfer at the electrode/electrolyte interface, and giving rise to fast reaction kinetics. In addition, highly concentrated catholytes possess an intrinsically low E/S ratio. For example, the E/S ratio of 1.5 M Li2S6 catholyte is only 3.5 μL mg−1, which is difficult to achieve in sulfur particle electrodes. However, the flooded amounts of LPSs in carbon/catholyte electrodes induce a severe shuttling effect due to the poor interaction between the nonpolar carbon host and polar LPSs, leading to a short cycle life. Thus, introducing polar electrocatalysts in carbon/catholyte becomes imperative.

Question: What's the cathode?
Increasing the areal sulfur loading and decreasing the amount of electrolyte in cathodes are natural methods to meet the above requirements. However, thick sulfur electrodes suffer cracking and peeling off problems during slurry casting, thus damaging the electrode integrity. Another obstacle for thick electrodes is the poor immersion of the electrolyte, which restrains the effective sulfur utilization. A promising alternate approach is to use a polysulfide solution, designated as a catholyte, as the starting material. The liquid catholyte is ready to immerse and envelope the surface of the conductive host, thus facilitating rapid charge transfer at the electrode/electrolyte interface, and giving rise to fast reaction kinetics. In addition, highly concentrated catholytes possess an intrinsically low E/S ratio. For example, the E/S ratio of 1.5 M Li2S6 catholyte is only 3.5 μL mg−1, which is difficult to achieve in sulfur particle electrodes. However, the flooded amounts of LPSs in carbon/catholyte electrodes induce a severe shuttling effect due to the poor interaction between the nonpolar carbon host and polar LPSs, leading to a short cycle life. Thus, introducing polar electrocatalysts in carbon/catholyte becomes imperative.

Question: What's the electrolyte?
Fig. 3(a) and (d) show the results of ion conductivity through EIS measurements of the porous NASICON pellets and epoxy-NASICON pellets, respectively. The NASICON ceramics sintered at 1100 °C had an ionic conductivity of 1.76 × 10−4 S cm−1. A cross-sectional SEM image of the NASICON pellet sintered at 1100 °C is shown in Fig. 3(b). Here, the solid electrolyte secures the ion transfer channel after sintering, leaving pores to remain inside. When the epoxy polymer is added to the sample, the polymer material sufficiently fills the internal pores (Fig. 3(e)). In the SEM image, it was confirmed that the empty space between the NASICON crystals was filled with a black material, which was identified as a polymer material containing C through the EDS analysis shown in Fig. 3(c) and (f). The detailed EDS analysis results for each component can be seen in ESI Fig. S4.† Comparing the components of Na, Si, Zr, and P, which are all contained in NASICON, with the components of C, which are only contained in the epoxy polymers, we can see that the epoxy polymer is completely contained in the inner pores. In the same sample, Na-ions only move through the connected ceramics, which means that adding epoxy polymers does not affect the ion conduction. The ionic conductivity after epoxy treatment of the NASICON pellet is determined to be 1.45 × 10−4 S cm−1. Therefore, epoxy polymer is not involved in the ion transport mechanism, so it can increase the physical strength while maintaining the existing ion conductivity.

Question: What's the electrolyte?
Since the capacitance in redox supercapacitors is mainly produced by the fast faradaic reaction occurring near a solid electrode surface at an appropriate potential, a relatively short diffusion path can be provided by nanostructured materials to improve the power density of supercapacitors. Therefore, electrode materials composed of NCPs have recently received consideration for supercapacitors. In addition, porous nanostructures increase the contact area between electrolyte and active materials. These two features lead to fast reaction kinetics. Electrode materials in supercapacitors essentially involve processes at the interface between an electrode and an electrolyte solution. Increasing the area of the interface is expected to increase the rate of the process. Porous electrode materials with high surface area per unit volume, especially with structural elements on the nanometer scale, have received considerable attention. Thus, active electrodes with meso- or nanoporous structures and good conductivity are highly desirable for high power densities.

Question: What's the electrolyte?
Electrolyte additives may modify lithium deposition in several different ways, e.g. by influencing initial SEI formation on the current collector, the nucleation stage of lithium metal deposition, the growth of lithium metal deposits, or some combination thereof. To investigate during which step of lithium metal electrodeposition HF plays an active role, a cell was first galvanostatically brought down to 0 V vs. the counter electrode (CE, Li/Li+) at 0.5 mA cm−2 in LP30 containing 100 ppm added HF to form the initial SEI on copper (Fig. 3a). The electrolyte was then removed, the cell rinsed with as-received LP30, and refilled with as-received LP30 for deposition of lithium metal (Fig. 3b). There is no voltage plateau ∼2 V indicative of HF reduction, but we observe an additional small amount of capacity below 1 V which is consistent with solvent reduction. Lithium metal with a highly monodispersed columnar morphology (Fig. 3c) was still deposited although there was no HF in the electrolyte during electroplating. This demonstrates that it is the initial SEI on copper which directs the microstructure and that HF does not play an active role beyond the initial SEI formation. This experimental evidence is in agreement with studies in the literature that report the formation of a columnar microstructure without additives when a LiF rich layer was deposited ex situ on copper prior to cell assembly.

Question: What's the electrolyte?
The fabrication of the nanomesh-based cathodes is performed in several steps, starting from the formation of the AAO template, growth of the nanomesh, deposition of the active material precursor and finally its activation by reaction with a lithium source (Fig. 1). In our approach, we focused on lithiated manganese oxides (here, generally abbreviated as LMO) as the active cathode material since they can be synthesized at relatively low temperatures and their precursor (MnO2) can be easily conformally electrodeposited onto high aspect ratio structures. This made LMO the natural choice for demonstrating the potential of nanomesh-based electrodes for Li-ion batteries. It is worth noting that LMO also show a relatively high reduction potential vs. Li+/Li (for example, ∼2.9 V for the layered LiMnO2 and 4–3 V for spinel LiMn2O4 ( ), are cheap and not toxic, but suffer from limited stability when cycled in liquid electrolytes.

Question: What's the cathode?
Answer:  lithiated manganese oxides
The fabrication of the nanomesh-based cathodes is performed in several steps, starting from the formation of the AAO template, growth of the nanomesh, deposition of the active material precursor and finally its activation by reaction with a lithium source (Fig. 1). In our approach, we focused on lithiated manganese oxides (here, generally abbreviated as LMO) as the active cathode material since they can be synthesized at relatively low temperatures and their precursor (MnO2) can be easily conformally electrodeposited onto high aspect ratio structures. This made LMO the natural choice for demonstrating the potential of nanomesh-based electrodes for Li-ion batteries. It is worth noting that LMO also show a relatively high reduction potential vs. Li+/Li (for example, ∼2.9 V for the layered LiMnO2 and 4–3 V for spinel LiMn2O4 ( ), are cheap and not toxic, but suffer from limited stability when cycled in liquid electrolytes.

Question: What's the cathode?
Answer: LMO
Acoustic wave velocity is determined by the speed of wave propagation through a medium with defined thickness. While the wave arrival time can be determined from the measured acoustic signal, thickness must be measured independently to verify the wave velocity. The expansion and contraction of a pouch cell during cycling can be imaged with transmission X-ray microscopy (TXM), which has sufficient range and pixel resolution to measure both the total cell thickness and the average layer thicknesses. TXM parameters were optimized with exposure time of 20 seconds, beam voltage of 140 kV, a 0.4× objective lens and 90° projection angle (Table 1). Fig. 1 illustrates the experimental configuration and example radiographs of the mechanical expansion of a pouch cell upon cycling. The commercial pouch cell chosen (LiCoO2/graphite, 210 mA h nominal capacity) has a total thickness of approximately 5.6 mm when fully charged. The measured thickness varies between 5.4 and 5.6 mm (∼4% change) at a rate of 1C. There is less variation (∼0.5%) at a rate of 3C because of less attainable capacity before hitting the 4.5 V voltage cutoff on charge. The thickness changes are dominated by the ∼10% volume expansion and contraction of graphite anodes upon lithiation/delithiation. With 15 double-sided anodes and cathodes, each of the 30 cell layers (one layer is defined as an anode, a cathode, with a separator layer in between each electrode) is approximately 170 μm in thickness as measured by average peak-to-peak spacing (additional information on pixel thresholds for thickness measurements can be found in Fig. S1–S5†).

Question: What's the cathode?
Then, Na metal was placed on the surface of the UV curing polymer electrolyte, and the product of a cell test in which a Na metal/solid electrolyte/cathode was made was placed in a 2032-coin cell. All steps were processed in a glovebox with less than 10 ppm for both oxygen and moisture. When manufacturing the bipolar stacked cell, a coin cell was prepared by putting Al foil between the two solid electrolyte cells.

Question: What's the cathode?
In order to evaluate the electrochemical performance of the obtained electrodes, two-electrode Zn–MnO2 batteries were assembled using COG@MnO2 as the cathode and COG@Zn as the anode in an aqueous electrolyte containing 2 M ZnSO4 and 0.1 M MnSO4. The typical cyclic voltammetry (CV) curves of the aqueous COG@MnO2//COG@Zn battery at different scan rates are shown in Fig. 3d. There are two reduction peaks at around 1.2 and 1.4 V, which should be ascribed to the zinc insertion into MnO2 and the subsequent reduction of Mn(IV) to the Mn(III)/Mn(II) states. Similarly, the oxidation peak and shoulder appear at 1.6–1.8 V, corresponding to Zn-extraction from the MnO2 cathode as the Mn(III)/Mn(II) states undergo oxidation to the Mn(IV) state. The overall reaction of the battery can be formulated as follows:

Question: What's the cathode?
Answer: COG@MnO2
In order to evaluate the electrochemical performance of the obtained electrodes, two-electrode Zn–MnO2 batteries were assembled using COG@MnO2 as the cathode and COG@Zn as the anode in an aqueous electrolyte containing 2 M ZnSO4 and 0.1 M MnSO4. The typical cyclic voltammetry (CV) curves of the aqueous COG@MnO2//COG@Zn battery at different scan rates are shown in Fig. 3d. There are two reduction peaks at around 1.2 and 1.4 V, which should be ascribed to the zinc insertion into MnO2 and the subsequent reduction of Mn(IV) to the Mn(III)/Mn(II) states. Similarly, the oxidation peak and shoulder appear at 1.6–1.8 V, corresponding to Zn-extraction from the MnO2 cathode as the Mn(III)/Mn(II) states undergo oxidation to the Mn(IV) state. The overall reaction of the battery can be formulated as follows:

Question: What's the anode?
Answer: COG@Zn
In order to evaluate the electrochemical performance of the obtained electrodes, two-electrode Zn–MnO2 batteries were assembled using COG@MnO2 as the cathode and COG@Zn as the anode in an aqueous electrolyte containing 2 M ZnSO4 and 0.1 M MnSO4. The typical cyclic voltammetry (CV) curves of the aqueous COG@MnO2//COG@Zn battery at different scan rates are shown in Fig. 3d. There are two reduction peaks at around 1.2 and 1.4 V, which should be ascribed to the zinc insertion into MnO2 and the subsequent reduction of Mn(IV) to the Mn(III)/Mn(II) states. Similarly, the oxidation peak and shoulder appear at 1.6–1.8 V, corresponding to Zn-extraction from the MnO2 cathode as the Mn(III)/Mn(II) states undergo oxidation to the Mn(IV) state. The overall reaction of the battery can be formulated as follows:

Question: What's the electrolyte?
Answer: 2 M ZnSO4 and 0.1 M MnSO4
The UTCNF//Zn and CNF//Zn batteries were assembled using UTCNF or CNF cathodes (an area of 1 × 1 cm2 and a thickness of 0.15 cm) and a Zn plate anode with 6 M KOH + 0.5 M Zn(Ac)2 as the electrolyte. The total mass of the UTCNF electrode was ∼32.3 mg and the corresponding hydroxide formation rate was ∼18.6%. Galvanostatic charge–discharge (GCD) experiments were performed using a multichannel battery testing system (Land CT 2001A). Cyclic voltammetry (CV) curves and electrochemical impedance spectra (EIS) were collected on an electrochemical workstation (PARSTAT MC).

Question: What's the cathode?
Answer: CNF
In summary, active catholyte has been applied to assemble a high-performance hybrid supercapacitor, which relies on the reversible conversion between soluble Mn2+ and solid MnO2 at the cathode and the redox of Ti–O with the bonding/de-bonding of H3O+ at the 400-KOH-Ti3C2 anode. The well-separated potential window between the cathode and anode leads to a hybrid supercapacitor with a wide voltage window of 1.7 V. This hybrid supercapacitor achieves a high energy density of 43.4 W h kg−1, without using any ion-selective membrane, and super-long cycle life (75% retention after 20000 cycles). Furthermore, the hybrid supercapacitor can operate well even with the frozen electrolyte at −70 °C. These inspiring results provide a new strategy to design high-performance hybrid supercapacitors for low temperature applications.

Question: What's the cathode?
Answer: MnO2
In summary, MoP was synthesized on nickel foam, on which NiCo-LDH was electrodeposited to form catalyst electrodes (MoP@NiCo-LDH/NF-x), where x represents the electrodeposition time period, and they were explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea–water or water electrolysis. The morphology and catalytic performance were investigated using a series of physical characterization and electrochemical tests. The results show that at an electrolysis current density of 100 mA cm−2, the anode potential of the MoP@NiCo-LDH/NF-20 electrode is 1.392 V (vs. RHE) for UOR, 233 mV less than that of an IrO2/NF electrode (1.625 V); and the cathode potential of the MoP@NiCo-LDH/NF-20 electrode is 0.255 V (vs. RHE) for HER, closest to that of IrO2/NF (170 mV). For the two-electrode electrolyser (MoP@NiCo-LDH/NF-20‖MoP@NiCo-LDH/NF-20), the cell voltage is as low as 1.405 V for urea–water electrolysis and 1.697 V for water electrolysis at a current density of 100 mA cm−2, even lower than those of a Pt/C/NF‖IrO2/NF cell. Moreover, after 20 hours of continuous electrolysis, the performance and morphology of the catalyst are almost unchanged, indicating that it has both high activity and stability. The results show that the developed MoP@NiCo-LDH/NF-20 is a promising bifunctional catalyst.

Question: What's the cathode?
Answer: MoP@NiCo-LDH/NF-20
In summary, MoP was synthesized on nickel foam, on which NiCo-LDH was electrodeposited to form catalyst electrodes (MoP@NiCo-LDH/NF-x), where x represents the electrodeposition time period, and they were explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea–water or water electrolysis. The morphology and catalytic performance were investigated using a series of physical characterization and electrochemical tests. The results show that at an electrolysis current density of 100 mA cm−2, the anode potential of the MoP@NiCo-LDH/NF-20 electrode is 1.392 V (vs. RHE) for UOR, 233 mV less than that of an IrO2/NF electrode (1.625 V); and the cathode potential of the MoP@NiCo-LDH/NF-20 electrode is 0.255 V (vs. RHE) for HER, closest to that of IrO2/NF (170 mV). For the two-electrode electrolyser (MoP@NiCo-LDH/NF-20‖MoP@NiCo-LDH/NF-20), the cell voltage is as low as 1.405 V for urea–water electrolysis and 1.697 V for water electrolysis at a current density of 100 mA cm−2, even lower than those of a Pt/C/NF‖IrO2/NF cell. Moreover, after 20 hours of continuous electrolysis, the performance and morphology of the catalyst are almost unchanged, indicating that it has both high activity and stability. The results show that the developed MoP@NiCo-LDH/NF-20 is a promising bifunctional catalyst.

Question: What's the anode?
Answer: MoP@NiCo-LDH/NF-20 electrode
In summary, MoP was synthesized on nickel foam, on which NiCo-LDH was electrodeposited to form catalyst electrodes (MoP@NiCo-LDH/NF-x), where x represents the electrodeposition time period, and they were explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea–water or water electrolysis. The morphology and catalytic performance were investigated using a series of physical characterization and electrochemical tests. The results show that at an electrolysis current density of 100 mA cm−2, the anode potential of the MoP@NiCo-LDH/NF-20 electrode is 1.392 V (vs. RHE) for UOR, 233 mV less than that of an IrO2/NF electrode (1.625 V); and the cathode potential of the MoP@NiCo-LDH/NF-20 electrode is 0.255 V (vs. RHE) for HER, closest to that of IrO2/NF (170 mV). For the two-electrode electrolyser (MoP@NiCo-LDH/NF-20‖MoP@NiCo-LDH/NF-20), the cell voltage is as low as 1.405 V for urea–water electrolysis and 1.697 V for water electrolysis at a current density of 100 mA cm−2, even lower than those of a Pt/C/NF‖IrO2/NF cell. Moreover, after 20 hours of continuous electrolysis, the performance and morphology of the catalyst are almost unchanged, indicating that it has both high activity and stability. The results show that the developed MoP@NiCo-LDH/NF-20 is a promising bifunctional catalyst.

Question: What's the electrolyte?
Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.

Question: What's the cathode?
Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.

Question: What's the anode?
Answer: penta-graphene
Recently, the atomic-level thickness and large surface area of 2D materials are beneficial to the generation of carriers on the surface and separation of photogenerated carriers. Typically, in comparison to their 3D counterparts, 2D materials present extremely numerous active sites, high carrier mobility, and controllable interface, which offer a large number of advantages for catalysts, electronics, optoelectronics, etc. Among them, penta-type materials have been developed as a series of novel 2D materials. For instance, Yang et al. reported a novel 2D material, penta-Pt2N4, with a large direct band gap, high carrier mobility and high Young's modulus, suggesting numerous potential applications in nanoelectronics. Xiao et al. found that penta-graphene shows desirable electrochemical performance and it may be a potential candidate for Li/Na-ion battery anodes. However, bulk pyrite-SiAs2 has been synthesized under high pressure and validated as a semiconductor decades ago. Meanwhile, this type of pyrite structure can form a 2D penta structure after cleaving the plane, but 2D penta-SiAs2 has not yet been explored.

Question: What's the electrolyte?
Flexible supercapacitors are playing an increasingly important role in energy storage due to their viability in flexible intelligent wearable electronic devices, which require irregular power supply at different discharge rates. Two-dimensional (2D) nanomaterials have gradually become potential electrode materials for flexible supercapacitors due to their atomic thickness and electrochemically active surface, especially since they allow the development of binder-free flexible electrodes with improved capacitance. 2D materials can provide slit-shaped ion diffusion channels that enable fast movement of electrolyte ions into the electrode bulk.

Question: What's the electrolyte?