An Air-Stable and Li-Metal-Compatible Glass-Ceramic Electrolyte enabling High-Performance All-Solid-State Li Metal Batteries

The development of all-solid-state Li metal batteries (ASSLMBs) has attracted significant attention due to their potential to maximize energy density and improved safety compared to the conventional liquid-electrolyte-based Li-ion batteries. However, it is very challenging to fabricate an ideal solid-state electrolyte (SSE) that simultaneously possesses high ionic conductivity, excellent air-stability, and good Li metal compatibility. Herein, a new glass-ceramic Li3.2P0.8Sn0.2S4 (gc-Li3.2P0.8Sn0.2S4) SSE is synthesized to satisfy the aforementioned requirements, enabling high-performance ASSLMBs at room temperature (RT). Compared with the conventional Li3PS4 glass-ceramics, the present gc-Li3.2P0.8Sn0.2S4 SSE with 12% amorphous content has an enlarged unit cell and a high Li+ ion concentration, which leads to 6.2-times higher ionic conductivity (1.21 x 10(-3) S cm(-1) at RT) after a simple cold sintering process. The (P/Sn)S-4 tetrahedron inside the gc-Li3.2P0.8Sn0.2S4 SSE is verified to show a strong resistance toward reaction with H2O in 5%-humidity air, demonstrating excellent air-stability. Moreover, the gc-Li3.2P0.8Sn0.2S4 SSE triggers the formation of Li-Sn alloys at the Li/SSE interface, serving as an essential component to stabilize the interface and deliver good electrochemical performance in both symmetric and full cells. The discovery of this gc-Li3.2P0.8Sn0.2S4 superionic conductor enriches the choice of advanced SSEs and accelerates the commercialization of ASSLMBs.

Automated summary

The study synthesized a new glass-ceramic solid-state electrolyte with high ionic conductivity and excellent air-stability, which can be used for the preparation of high-performance all-solid-state Li metal batteries.