Li₂S-Based Composite Cathode with in Situ-Generated Li₃PS₄ Electrolyte on Li₂S for Advanced All-Solid-State Lithium–Sulfur Batteries

All-solid-state lithium–sulfur batteries (ASSLSBs) are considered to be a promising solution for the next generation of energy storage systems due to their high theoretical energy density and improved safety. However, the practical application of ASSLSBs is hindered by several critical challenges, including the poor electrode/electrolyte interface, sluggish electrochemical kinetics of solid–solid conversion between S and Li 2 S in the cathode, and big volume changes during cycling. Herein, the 85(92Li 2 S-8P 2 S 5 )-15AB composite cathode featuring an integrated structure of a Li 2 S active material and Li 3 PS 4 solid electrolyte is developed by in situ generating a Li 3 PS 4 glassy electrolyte on Li 2 S active materials, resulting from a reaction between Li 2 S and P 2 S 5 . The well-established composite cathode structure with an enhanced electrode/electrolyte interfacial contact and highly efficient ion/electron transport networks enables a significant enhancement of redox kinetics and an areal Li 2 S loading for ASSLSBs. The 85(92Li 2 S-8P 2 S 5 )-15AB composite demonstrates superior electrochemical performance, exhibiting 98% high utilization of Li 2 S (1141.7 mAh g (Li2S) –1 ) with both a high Li 2 S active material content of 44 wt % and corresponding areal loading of 6 mg cm –2 . Moreover, the excellent electrochemical activity can be maintained even at an ultrahigh areal Li 2 S loading of 12 mg cm –2 with a high reversible capacity of 880.3 mAh g –1, corresponding to an areal capacity of 10.6 mAh cm –2 . This study provides a simple and facile strategy to a rational design for the composite cathode structure achieving fast Li–S reaction kinetics for high-performance ASSLSBs.