A New Amorphous Lithium-ion Conductor in the System Li2S–P2S3

Amorphous solid electrolytes in the system Li2S–P2S3 were obtained in a narrow composition range at around 66.7 mol % Li2S content by a high-energy ball-milling process. The 66.7Li2S·33.3P2S3 (mol %) sample showed the highest ion conductivity of 1.1 × 10^-4 S·cm^-1 at room temperature among the obtained samples. Cyclic voltammetry revealed that the sample had a wide electrochemical window of about 5 V.