A new approach: Li2S-P2S5 thin-films prepared by thermal evaporation as solid electrolytes

Li2S-P2S5 thin-film solid electrolytes are synthesized by using room-temperature thermal evaporation for use as lithium-ion conductors for all-solid-state Li-ion batteries. The local structures of 75.51Li2S:24.49P2S5 and 77.64Li2S:22.36P2S5 prepared in this way have hetero units that facilitate lithium-ion mobility. The lithium-ion conductivity at room temperature for the 77.64Li2S:22.36P2S5 thin-film (4.0 × 10−6 S cm−1) is higher than that for the 75.51Li2S:24.49P2S5 thin-film (1.2 × 10−6 S cm−1). The increased ion conductivity in the 77.64Li2S:22.36P2S5 film is due to the additional local P2S74− structure that forms a glassy state during the thermal evaporation process. The local structure can lead to a high mobility of Li+ ions in the Li2S-P2S5 system due to the non-bridging sulfide ions. Lithium-ion-conducting thin-films prepared by using thermal evaporation, as reported in this study, are promising solid electrolytes.