Observation of Chemomechanical Failure and the Influence of Cutoff Potentials in All-Solid-State Li–S Batteries

Because of a remarkably high theoretical energy density, the lithium–sulfur (Li–S) battery has attracted significant attention as a candidate for next-generation batteries. While employing solid electrolytes can provide a new avenue for high-capacity Li–S cells, all-solid-state batteries have unique failure mechanisms such as chemomechanical failure due to the volume changes of active materials. In this study, we investigate all-solid-state Li–S model cells with differently processed cathode composites and elucidate a typical failure mechanism stemming from irreversible Li2S formation in the cathode composites. Reducing the particle size is key to minimizing the influence of volume changes, and a capacity of >1000 mAh gsulfur–1 is achieved by ball milling of the cathode composites. In addition, the long-term stability of the ball-milled cathode is investigated by varying the upper and lower cutoff potentials for cycling, which results in the unveiling of the significantly detrimental role of the lower cut...