All-solid-state lithium secondary batteries using the 75Li2S·25P2S5 glass and the 70Li2S·30P2S5 glass—ceramic as solid electrolytes

Abstract The 70Li 2 S·30P 2 S 5 glass–ceramic showed high ion conductivity of 1.5 × 10 −3  S cm −1 at room temperature. The 75Li 2 S·25P 2 S 5 glass showed ion conductivity of 5.0 × 10 −4  S cm −1 at room temperature and high chemical stability. All-solid-state C/LiCoO 2 cells using those materials as solid electrolytes were assembled. Their cell performance were compared. The cell using the 70Li 2 S·30P 2 S 5 glass–ceramic showed superior rate performance to the cell using the 75Li 2 S·25P 2 S 5 glass. On the other hand, the cell using the 75Li 2 S·25P 2 S 5 glass showed superior cycle performance to the cell using the 70Li 2 S·30P 2 S 5 glass–ceramic. It was suggested that solid electrolytes in all-solid-state batteries preferably had both high ion conductivity and high chemical stability.