Solution Processing via Dynamic Sulfide Radical Anions for Sulfide Solid Electrolytes

Abstract

Solution processing technology for the manufacturing of all‐solid‐state batteries (ASSBs) holds great promise of scalability and low cost over ball milling and solid‐state methods. However, conventional liquid‐phase synthesis for solid electrolytes has yet to translate into large‐scale manufacturing to address commercialization challenges. Herein, solution processing via dynamic sulfide radical anions is developed, providing rapid and scalable manufacturing of Li7P3S11 solid electrolytes (SEs). A mixture of Li2S, P2S5, and excess elemental sulfur in a mixed solvent of acetonitrile, tetrahydrofuran, and ethanol forms a homogenous precursor solution containing the S3 ·− radical anion. The presence of ethanol enhances the chemical stability of S3 ·−. The resulting sulfide radical anions serve as a mediator with two strategies: the soluble polysulfide formation and activation of P2S5, and thus allows the generation of the precursor solution in 2 min. The Li7P3S11 is prepared in 2 h without the need for ball milling or high‐energy treatment, which shows higher ionic conductivity (1.2 mS cm−1 at 25 °C) and excellent cell performance of ASSBs cells than Li7P3S11 prepared by ball milling. The solution processing technology reported here paves the way for the accelerated adoption of practical ASSBs manufacturing.