Preparation of Li 2 S–P 2 S 5 Amorphous Solid Electrolytes by Mechanical Milling

Amorphous solid electrolytes in the Li 2 S–P 2 S 5 system were prepared successfully from a mixture of crystalline Li 2 S and P 2 S 5 , using a mechanical milling technique. The amorphous‐forming region was extended to higher Li 2 S compositions by mechanical milling, compared with melt quenching. The pelletized samples of the 75Li 2 S·25P 2 S 5 (on a mole‐percent basis) amorphous powders obtained by mechanical milling for 20 h exhibited high conductivity (2 × 10 −4 S/cm at room temperature) and an activation energy for conduction of 34 kJ/mol. The lithium‐ion transport number of the amorphous powders was almost unity.