Structure, ionic conductivity and electrochemical stability of Li2S–P2S5–LiI glass and glass–ceramic electrolytes

Abstract

The structures, ionic conductivities and electrochemical stabilities of the (100−x)(0.7Li2S·0.3P2S5)·xLiI glass and glass–ceramic electrolytes were investigated. The (100−x)(0.7Li2S·0.3P2S5)·xLiI glasses and glass–ceramics were prepared by mechanical milling in the composition range 0≤x(mol%)≤20. All the glasses and glass–ceramics had P2S74− and PS43− ions. The Li7P3S11 crystals were observed in all the glass–ceramics. On the other hand, crystals containing PS43− ions were mainly precipitated in the glass–ceramics with increasing the LiI content. The conductivities of glasses increased with increasing the LiI content, and the glass at x=20 showed the highest conductivity of 5.6×10−4Scm−1. While the conductivity of glass–ceramics at x=0 was 4.2×10−3Scm−1, it decreased sharply with increasing the LiI content. Cyclic voltammetry indicated that the 80(0.7Li2S·0.3P2S5)·20LiI glasses exhibited a wide electrochemical stability up to 10V vs. Li+/Li.