Amorphous solid electrolytes in the system Li2S-Al2S3-SiS2 prepared by mechanical milling

Amorphous solid electrolytes in the ternary system Li2S-Al2S3-SiS2 were successfully prepared by mechanical milling. The ambient temperature conductivity of the 60Li2S·10AlS1.5·30SiS2 (mol%) sample reached over 10−4 S cm−1 with amorphization by mechanical milling for 40 h. The binary Li2S-Al2S3 amorphous electrolytes, which have not been synthesized by a conventional melt-quenching technique, were also obtained by mechanical milling. The 60Li2S·40AlS1.5 (mol%) amorphous electrolyte exhibited lower conductivity and higher activation energy for conduction than the 60Li2S·40SiS2 (mol%) amorphous electrolyte. The addition of SiS2 to Li2S-Al2S3 system monotonically increased electrical conductivity and decreased activation energy for conduction. The amorphous 60Li2S·10AlS1.5·30SiS2 material showed favorable features as a solid electrolyte such as unity of lithium ion transport number and wide electrochemical window.