Cathode coating is a key technology in sulfide-based all-solid-state batteries (ASSBs). The coating serves as a protector, suppressing side reactions at the sulfide/cathode active material interface. Lithium niobate (LiNbO₃) is a well-known coating material. In this study, sulfide-based ASSBs, which were uncoated and surface-coated with LiNbO₃, are subjected to cell operation testing and electrochemical impedance spectroscopy (EIS) in a low-temperature environment (i.e., −60 °C), where a commercial liquid-type lithium-ion battery (LIB) is unable to operate because of partial freezing and significant viscosity increase. Unlike liquid-type LIBs, the coated and uncoated ASSBs successfully discharge at −60 °C, emphasizing their applicability in low-temperature environments. The coated ASSB exhibits better low-temperature performance than the uncoated one. In the absence of coating, the deconvoluted EIS resistance data show an increase in some resistance components at low temperature.

In the present study, αMgCo_1.5Mn_0.5O₄-(1 − α)Mg_1.33V_1.57Ni_0.1O₄ was synthesized by a reverse co-precipitation method. The products were assigned to a spinel structure with a space group Fd3m based on powder X-ray diffraction analysis. Inductively coupled plasma-atomic emission spectroscopy revealed that the composition was not close to the target composition; the Mg content was higher and the V content was lower than expected. Charge/discharge cyclic tests showed that the discharge capacity exceeded 180 mAh g⁻¹ and that the cyclability was reversible up to 60 cycles at 90 °C with a cut-off voltage of 0.945 to −1.055 V vs. Ag/Ag⁺ (3.545–1.545 V vs. Mg/Mg²⁺) for α = 0.3. The electronic structure was analyzed using the maximum-entropy method based on a Rietveld analysis, and it was found that Mg insertion was easier for α = 0.3, 0.5, 0.9 than for MgCo_1.5Mn_0.5O₄ and Mg_1.33V_1.57Ni_0.1O₄. The strain in MO₆ octahedra for α = 0.1, 0.3, 0.5, 0.7 was smaller than that for MgCo_1.5Mn_0.5O₄ and Mg_1.33V_1.57Ni_0.1O₄, which suggests that the host structure was stabilized by forming a solid solution. A Rietveld analysis after the first discharge and second charge confirmed a partly reversible phase transition from the spinel phase to a rock-salt phase. The valence of the transition metals was examined by X-ray absorption fine structure (XAFS) measurements, and the Co and Mn K-edge spectra revealed that Co and Mn were present as Co^2.67+ to Co²⁺ and Mn⁴⁺ to Mn³⁺ species for α = 0.3. Both Co and Mn redox processes are considered to contribute to Mg intercalation. Extended XAFS (EXAFS) Co K-edge and Mn K-edge spectra for the powder specimens and after the first discharge and second charge showed that bonds between Co, V atoms and nearest-neighbor O atoms were distorted after the first discharge, and that this distortion was relaxed after the second charge.

Carbon-coated SiO (SiO-C) sheet-type electrodes without sulfide-based solid electrolytes on a current collector worked as negative electrode materials for all-solid-state batteries. The SiO-C sheet-type electrodes exhibited the high capacity (ca. 1500 mAh g⁻¹), good cycle and high-rate discharge performance for all-solid-state batteries using sulfide solid electrolytes at room temperature. It is notice that SiO-C film electrodes are expected to promote new ionic-electronic conducting interface for sulfide-based solid electrolytes in all-solid-state batteries.

To clarify the contribution of defect structure of CaWO₄-based system on the oxide ion conduction properties, we doped both cesium and lanthanum ions into CaWO₄ as Ca_0.9Cs_xLa_0.1−xWO_4.05−x. Scheelite-type structured solid solution can be obtained for the Cs-rich region (x ≥ 0.05) with oxygen deficiency, while second phase appears for La-rich region (x ≤ 0.025) assuming excess oxide ions. In the present system, a bend in Arrhenius plot of conductivity is observed around 850 °C as the typical CaWO₄-based system even co-doping with La ions. In terms of the compositional dependence, ionic conduction develops from x = 0.05 with the amount of cation vacancy below 800 °C, while the conductivity enhancement starts at the La-rich region above 900 °C. This indicates that not only oxide ion vacancy but also interstitial attribute to the oxide ion conduction at high-temperature, which is also suggested by the activation energy.

The current worldwide energy problems resulting from global environmental issues require highly efficient, environmentally benign energy storage technologies. Among various innovative battery types, rechargeable batteries based on magnesium (Mg) metal anodes represent an attractive option because of their large volumetric/gravimetric capacities and the cost-effectiveness of the base Mg metal. To realize practical Mg batteries, intense efforts have been focused on the development of cathode and electrolyte materials. Defect spinel oxides represent an emerging class of cathode active materials. The representative compound ZnMnO₃ has sufficient capacities for superlong cycles at elevated temperatures, owing to the suppression of the undesired spinel-rocksalt phase transition. To further enhance the electrochemical performance of ZnMnO₃, hydrothermal treatment was applied to synthesize fine ZnMnO₃ nanoparticles. By controlling the pH of precursor solutions, treatment temperature, and reaction duration, fine ZnMnO₃ nanoparticles with a remarkably large surface area can be obtained. Our ZnMnO₃, prepared using hydrothermal treatment, was able to deliver larger capacities compared with those obtained using the typical coprecipitation method. Furthermore, the hydrothermally treated ZnMnO₃ allowed stable battery cycling even at 30 °C; this was achieved by combining the highly efficient, electrochemically stable electrolyte and the ZnMnO₃ nanoparticles with the shortened diffusion path.

In this work, the Zn–Ta coating was electrodeposited from DMI–ZnCl₂–TaCl₅ solvate ionic liquid. The electrochemical reaction was studied by cyclic voltammetry using titanium as working electrode. The onset potential of zinc and tantalum co-deposition was −0.7 V (vs. Ag). Moreover, potentiostatic electrodeposition experiments were conducted to investigate the influence of potential and temperature on the morphology of the coating. X-ray photoelectron spectroscopy analysis confirmed that the coating obtained by electrodeposition at −1.6 V (vs. Ag) and 353 K was composed of Zn, Ta, ZnO, and Ta₂O₅. The mass fraction of element tantalum was 6.21 %, and metallic tantalum accounted for 11.54 % of the mass of element tantalum. The corrosion current density of the Zn–Ta coating was 1.83 × 10⁻⁴ A cm⁻².

The reaction kinetics of electrochemical lithiation/delithiation in a composite consisting of black phosphorus and cup-stacked carbon nanotube (BP-CSCNT) were investigated. Two semicircles were observed in Nyquist plots at the high and low frequency regions, which were attributed to the resistance of lithium-ion transport through the surface film and the resistance of the alloying/dealloying reaction (charge-transfer resistance), respectively. The activation energy using the charge transfer reaction was evaluated from the temperature-dependence of the interfacial conductivity. Even with the use of ethylene carbonate-based and propylene carbonate electrolytes, the activation energy was calculated to be 25–26 kJ mol⁻¹, which is much smaller than that obtained with graphite electrodes and cathode materials. These results indicate that the ionic charge transfer process in BP-CSCNT composite electrodes is not coupled with the desolvation process and suggest that the charge transfer in BP-CSCNT is exceptionally fast compared to that in other insertion materials.

Due to its high energy density, lithium-air battery has been one of the research hotspots. However, there are still many issues that need to be addressed, especially when working in an open environment. In this paper, the pouch-type non-rechargeable lithium-air batteries were fabricated by using high loading air electrode and waterproof and breathable PDMS film, and their discharge performance in an open environment was studied. Due to the high waterproof and breathable performance of PDMS, the battery has better discharge and storage performance. The discharge time is more than 900 h, and the discharge time can reach more than 370 h after the battery is stored in the open environment for 1 month. The results of three electrodes and impedance test show that the electrolyte shortage is the main reason for the increase of polarization of the air electrode and the termination of the discharge of the lithium-air battery.