Preparation of Highly Lithium‐Ion Conductive 80Li2S·20P2S5 Thin‐Film Electrolytes Using Pulsed Laser Deposition

Highly lithium-ion conductive Li2S–P2S5 thin films were prepared using pulsed laser deposition at room temperature. The ambient Ar gas pressure during deposition strongly affected the thin films' chemical compositions and local structures. The chemical composition and the local structure of the 80Li2S·20P2S5 thin film prepared under 5 Pa showed good agreement with those of the highly lithium-ion conducting 80Li2S·20P2S5 glass powder prepared by mechanical milling. The ionic conductivity at 25°C and the activation energy for conduction of the as-deposited 80Li2S·20P2S5 thin films were, 7.9 × 10−5 S/cm and 43 kJ/mol, respectively. The ionic conductivity of the 80Li2S·20P2S5 thin film was increased to 2.8 × 10−4 S/cm through heat treatment. The highly lithium-ion conducting thin-films reported in this study are promising electrolytes for developing all-solid-state lithium batteries.