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

Zhao, Feipeng; Alahakoon, Sandamini H; Adair, Keegan; Zhang, Shumin; Xia, Wei; Li, Weihan; Yu, Chuang; Feng, Renfei et al. · Adv Mater · 2021

basic_science · Level V

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Abstract

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 Li<sub>3.2</sub> P<sub>0.8</sub> Sn<sub>0.2</sub> S<sub>4</sub> (gc-Li<sub>3.2</sub> P<sub>0.8</sub> Sn<sub>0.2</sub> S<sub>4</sub> ) SSE is synthesized to satisfy the aforementioned requirements, enabling high-performance ASSLMBs at room temperature (RT). Compared with the conventional Li<sub>3</sub> PS<sub>4</sub> glass-ceramics, the present gc-Li<sub>3.2</sub> P<sub>0.8</sub> Sn<sub>0.2</sub> S<sub>4</sub> SSE with 12% amorphous content has an enlarged unit cell and a high Li<sup>+</sup> ion concentration, which leads to 6.2-times higher ionic conductivity (1.21 × 10<sup>-3</sup> S cm<sup>-1</sup> at RT) after a simple cold sintering process. The (P/Sn)S<sub>4</sub> tetrahedron inside the gc-Li<sub>3.2</sub> P<sub>0.8</sub> Sn<sub>0.2</sub> S<sub>4</sub> SSE is verified to show a strong resistance toward reaction with H<sub>2</sub> O in 5%-humidity air, demonstrating excellent air-stability. Moreover, the gc-Li<sub>3.2</sub> P<sub>0.8</sub> Sn<sub>0.2</sub> S<sub>4</sub> 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-Li<sub>3.2</sub> P<sub>0.8</sub> Sn<sub>0.2</sub> S<sub>4</sub> superionic conductor enriches the choice of advanced SSEs and accelerates the commercialization of ASSLMBs.