Synthesis of lithium oxy-thiophosphate solid electrolytes with LiGePS structure by a liquid phase process using 2-propanol.

Lithium oxy-thiophosphates isostructural with LiGePS (LGPS) were synthesized by a liquid-phase process using 2-propanol as the solvent and LiS and PS as the starting materials. The XRD and P NMR results indicate that the synthesized compound has a slightly shrieked LGPS-type crystal structure where sulfur in PS is partially replaced by oxygen. The sample synthesized from the nominal composition of LiS : PS = 2.5 : 1 and at the annealing temperature of 300 °C exhibited the ionic conductivity of 1.6 × 10 S cm at 25 °C. The synthesized solid electrolyte was found to be electrochemically stable in the potential range of 0-5 V, and also relatively stable under air with low relative humidity.