Understanding the Stability of Copper Current Collector with Sulfide Electrolyte in All‐Solid‐State Batteries

Abstract Sulfide‐based all‐solid‐state batteries (ASSBs) have attracted wide attention due to their notable advantages in energy density and enhanced safety. However, whether or not copper (Cu) current collectors can be adopted in sulfide‐based ASSBs remains unclear, as sulfide electrolyte (SE) may react with Cu, causing premature failure of the ASSBs. Herein it is reported that in the presence of traces amount of water, e.g. in a dry room with a dew point of −50 °C, the SE reacts with water to produce H 2 S, which corrodes Cu to produce Cu 2 S, causing serious performance degradation to the ASSBs. Conversely, in an anhydrous environment (such as within a glove box), SE is virtually inert to Cu, rendering Cu a valid current collector. This study establishes the conditions that Cu can be used as the current collectors for sulfide‐based ASSBs, which provides important guidance for the industrialization of ASSBs.