A Review on Solid-State Li-S Battery: From the Conversion Mechanism of Sulfur to Engineering Design

Lithium-sulfur (Li-S) batteries attract sustained attention because of their ultrahigh theoretical energy density of 2567 Wh·kg^–1 and the actual value over 600 Wh·kg^–1. Solid-state Li-S batteries (SSLSBs) emerge in the recent two decades because of the enhanced safety when compared to the liquid system. As for the SSLSBs, except for the difference in the conversion mechanism induced by the cathode materials themselves, the physical-chemical property of solid electrolytes (SEs) also significantly affects their electrochemical behaviors. On account of various reported Li-S batteries, the advantages and disadvantages in performance and the failure mechanism are discussed in this review. Based on the problems of the reported SSLSBs such as lower energy density and faster capacity fading, the strategies of building high-performance SSLSBs are classified. The review aims to afford fundamental understanding on the conversion mechanism of sulfur and engineering design at full-cell level, so as to promote the development of SSLSBs.