High-Temperature Performance of All-Solid-State Lithium-Metal Batteries Having Li/Li₃PS₄Interfaces Modified with Au Thin Films

Li metal is very attractive as a negative electrode material for high-energy-density all-solid-state batteries owing to its high specific capacity and low electrochemical potential. However, short-circuiting of batteries upon formation of Li dendrites is a serious issue that hinders its successful practical application. An advantage of all-solid-state batteries is their inherent safety at high temperatures. In this study, the high-temperature performance of all-solid-state Li-metal batteries containing sulfide-glass electrolytes was investigated. Symmetric cells with Li 3 PS 4 electrolytes exhibited better Li dissolution-deposition performance at 100°C than at 25°C. In addition, inserting Au thin films at the Li/Li 3 PS 4 interface enabled stable operation of the symmetric cells at high current density (1.3 mA cm −2 ) and large areal capacity (6.5 mAh cm −2 ) without short-circuiting. All-solid-state Li-metal batteries with Au thin films (Li/Au/Li 3 PS 4 /LiNi 1/3 Mn 1/3 Co 1/3 O 2 ) exhibited high rate performance at 2.4 mA cm −2 and long lives of over 200 cycles at 100°C. The dissolution of the Au thin films into the Li metal is a possible reason for the enhanced electrochemical performance. These results indicate that interface modification and optimizing operating temperature are promising strategies to achieve all-solid-state batteries with high energy densities.