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 Li3PS4 electrolytes exhibited better Li dissolution-deposition performance at 100 degrees C than at 25 degrees C. In addition, inserting Au thin films at the Li/Li3PS4 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/Li3PS4/LiNi1/3Mn1/3Co1/3O2) exhibited high rate performance at 2.4 mA cm(-2) and long lives of over 200 cycles at 100 degrees 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. (C) 2018 The Electrochemical Society.