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

Abstract

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 75.51Li(2)S:24.49P(2)S(5) and 77.64Li(2)S:22.36P(2)S(5) prepared in this way have hetero units that facilitate lithium-ion mobility. The lithium-ion conductivity at room temperature for the 77.64Li(2)S:22.36P(2)S(5) thin-film (4.0 x 10(-6) S cm(-1)) is higher than that for the 75.51Li(2)S:24.49P(2)S(5) thin-film (1.2 x 10(-6) S cm(-1)). The increased ion conductivity in the 77.64Li(2)S:22.36P(2)S(5) film is due to the additional local P2S7 (4-) 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.