In Situ Li₃PS₄ Solid‐State Electrolyte Protection Layers for Superior Long‐Life and High‐Rate Lithium‐Metal Anodes

Abstract

Abstract A thin and adjustable Li 3 PS 4 (LPS) solid‐state electrolyte protection layer on the surface of Li is proposed to address the dynamic plating/stripping process of Li metal. The LPS interlayer is formed by an in situ and self‐limiting reaction between P 4 S 16 and Li in N ‐methyl‐2‐pyrrolidone. By increasing the concentration of P 4 S 16 , the thickness of the LPS layer can be adjusted up to 60 nm. Due to the high ionic conductivity and low electrochemical activity of Li 3 PS 4 , the intimate protection layer of LPS can not only prevent the formation of Li dendrites, but also reduces parasitic side reactions and improves the electrochemical performance. As a result, symmetric cells with the LPS protection layer can deliver stable Li plating/stripping for 2000 h. Full cells assembled with the LPS‐protected Li exhibit two times higher capacity retention in Li–S batteries (≈800 mAh g −1 ) at 5 A g −1 for over 400 cycles compared to their bare Li counterparts. Furthermore, high rate performances can be achieved with Li‐LPS/LiCoO 2 cells, which are capable of cycling at rates as high as 20 C. This innovative and scalable approach to stabilizing the Li anode can serve as a basis for the development of next‐generation high‐performance lithium‐metal batteries.