Materials with high formability and Li‐ion diffusivity are desired to realize safe bulk‐type all‐solid‐state Li‐ion batteries with high energy density. Spinel‐type Li2FeCl4, which is expected as a Li‐ion‐conductive electrode, adopts the high‐temperature cubic phase (space group: Fd‐3m) by a mechanochemical synthesis method. The powder‐compressed pellet shows a high relative density of 92% and large neck formation between the particles. An analysis of the distribution of relaxation times from the AC impedance results indicates that the contribution of the grain boundary impedance is almost negligible (≈3%) in the powder‐compressed pellet. Even the Li diffusion coefficient, which is underestimated by the Nernst–Einstein equation, is several orders of magnitude higher than those of conventional oxide and sulfide electrode materials. Analyzing the diffusion pathways using a classical force field calculation suggests that stabilizing the high‐temperature phase at room temperature delocalizes Li ions in the diffusion pathway, thus realizing high Li‐ion diffusivity. The Li2FeCl4 green compact containing 10 wt% carbon as an electron‐conductive additive shows a one‐electron charge reaction with a capacity of 126 mAh g−1, with no large overpotential at a high operating voltage of 3.6 V versus Li/Li+ at 30 °C.

This work presents a protocol employing the microwave photoconductivity decay (μ-PCD) for measurement of the carrier lifetime in semiconductor materials, especially SiC. In principle, excess carriers in the semiconductor generated via excitation recombine with time and, subsequently, return to the equilibrium state. The time constant of this recombination is known as the carrier lifetime, an important parameter in semiconductor materials and devices that requires a noncontact and nondestructive measurement ideally achieved by the μ-PCD. During irradiation of a sample, a part of the microwave is reflected by the semiconductor sample. Microwave reflectance depends on the sample conductivity, which is attributed to the carriers. Therefore, the time decay of excess carriers can be observed through detection of the reflected microwave intensity, whose decay curve can be analyzed for estimation of the carrier lifetime. Results confirm the suitability of the μ-PCD protocol in measuring the carrier lifetime in semiconductor materials and devices.

We report a facile strategy for the synthesis of cadmium and cobalt metal-organic frameworks (MOFs), and their subsequent conversion to the corresponding oxide. Thus, Cd-MOF and Co-MOF were prepared by successive ionic layer adsorption and reaction (SILAR) using Cd2+ or Co2+ cation precursors and a p-phenylenediamine anion precursor. As-synthesized particles with unique morphology were converted into CdO or Co3O4 after heat treatment under air. The resultant CdO and Co3O4 retained the original morphology of the MOF precursors. The optical and photoelectrochemical behavior of thus-prepared CdO was studied by diffuse reflectance spectroscopy and photovoltammetry. Finally, the capacitive behavior of the cobalt oxide electrode was assessed by cyclic voltammetry.