Designing solution chemistries for the low-temperature synthesis of sulfide-based solid electrolytes

Developing synthesis methods for high quality solid electrolytes has been a key issue for enabling all-solid-state batteries. As compared to conventional methods using mechanical ball milling, liquid-phase synthesis methods would provide a facile way to produce solid electrolytes by reducing the reaction time and heating temperature. The simplified process is also potentially applicable to scalable manufacturing. Here, we introduce a new solution-based synthesis method for an Li 2 S-P 2 S 5 solid electrolyte by adding a nucleophilic agent, LiSC 2 H 5 . The strong nucleophile can break the P-S bonds of P 2 S 5 , fully dissolving the P 2 S 5 in tetrahydrofuran (THF) and forming soluble intermediates. The modified synthesis protocol provides kinetically favorable conditions for P 2 S 5 to react with the insoluble Li 2 S, demonstrating the formation of a high quality β-Li 3 PS 4 solid electrolyte (1.32 × 10 −4 S cm −1 ) with a uniform particle shape. A new solution-based synthesis method to produce a high quality Li 2 S-P 2 S 5 solid electrolyte was developed by using a strong nucleophile of LiC 2 H 5 .