Synthesis of lithium oxy-thiophosphate solid electrolytes with Li(10)GeP(2)S(12) structure by a liquid phase process using 2-propanol

Lithium oxy-thiophosphates isostructural with Li(10)GeP(2)S(12) (LGPS) were synthesized by a liquid-phase process using 2-propanol as the solvent and Li(2)S and P(2)S(5) as the starting materials. The XRD and (31)P NMR results indicate that the synthesized compound has a slightly shrieked LGPS-type crystal structure where sulfur in PS(4)(3−) is partially replaced by oxygen. The sample synthesized from the nominal composition of Li(2)S : P(2)S(5) = 2.5 : 1 and at the annealing temperature of 300 °C exhibited the ionic conductivity of 1.6 × 10(−4) S cm(−1) 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.