Progress of the Interface Design in All‐Solid‐State Li–S Batteries

Lithium–sulfur (Li–S) batteries are one of the most promising next‐generation battery types for their high energy density and low cost. On the other hand, safety issues and poor cyclability strongly limit practical application. Solid‐state electrolytes (SSEs) can present as high ionic conductivity as aprotic electrolytes and eventually avoid the shuttle effect, which provides an ultimate solution for safe Li–S batteries with good cyclability. In this review, the recent achievements in all‐solid‐state Li–S batteries based on inorganic SSEs are summarized. Furthermore, the main attentions are paid to the interfaces, including metallic lithium|SSEs, SSEs|SSEs, and composite sulfur cathode|SSEs. The potential approaches to deal with these interfacial issues are proposed as well, such as composite SSEs with an asymmetric structure to enhance their compatibility with lithium anodes and sulfur cathodes, adding Li2O or LiF and increasing the densification to reduce the grain boundary resistance, and nanomaterials used to improve the kinetic process in cathode. The interfaces in all‐solid‐state Li–S batteries including metallic lithium| solid‐state electrolytes (SSEs), SSEs|SSEs, and composite sulfur cathode|SSEs are surveyed and the corresponding approaches to handle the interface issues are proposed toward better electrochemical performance.