Spontaneous gas–solid reaction on sulfide electrolytes for high-performance all-solid-state batteries

Abstract

Sulfide electrolytes with high ionic conductivity and facile formability are expected to replace the conventional flammable liquid electrolyte to construct high-energy and safe all-solid-state batteries (ASSBs). However, the practical use of sulfide electrolytes is mainly obstructed by their high sensitivity to humidity and instability to the high-voltage oxide cathodes. Herein, we solve these two problems of sulfide electrolytes by constructing a Li₂CO₃ interface through a spontaneous gas–solid reaction and achieve the enhanced electrochemical performance of ASSBs. Coupled with bare LiCoO₂, the ASSBs with CO₂-treated electrolyte or fabricated in a CO₂-rich environment show impressive electrochemical performance with a remarkable rate performance (65 mA h g⁻¹ at 3C) and excellent cycling retention (89.4% retention over 2100 cycles) at voltage up to 4.5 V vs. Li⁺/Li. The improved performance is attributed to the enhanced interfacial stability with low resistance and demonstrates the practical feasibility and even superiority of sulfide electrolytes based on current battery fabrication conditions.