A mixed-former effect on lithium-ion conductivities of the Li2S–GeS2–P2S5 amorphous materials prepared by a high-energy ball-milling process

Amorphous solid electrolytes containing large amount of Li2S were prepared in the system Li2S–GeS2–P2S5 by a high-energy ball-milling process. The region of amorphous-sample formation by the ball-milling process is much wider than the glass-forming region by a conventional melt-quenching method. The addition of a second network-forming sulfide, GeS2, to the Li2S–P2S5 system caused an enhancement of ion conductivities of the amorphous samples. The 95Li3PS4·5Li4GeS4 amorphous sample showed the highest lithium-ion conductivity 4.0×10−4 S cm−1 at room temperature among the obtained amorphous samples in the system Li2S–GeS2–P2S5. DC polarization measurements suggested that lithium-ion transport number of the 95Li3PS4·5Li4GeS4 sample was almost unity.