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

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 Li 2 CO 3 interface through a spontaneous gas-solid reaction and achieve the enhanced electrochemical performance of ASSBs. Coupled with bare LiCoO 2 , the ASSBs with CO 2 -treated electrolyte or fabricated in a CO 2 -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. Sulfide solid electrolytes modified by CO 2 /O 2 deliver enhanced moisture resistance and superior cathodic interfacial stability.