Carbon-free and binder-free Li-Al alloy anode enabling an all-solid-state Li-S battery with high energy and stability

Incompatibility of electrolytes with Li anode impedes the application of solid-state batteries. Aluminum with appropriate potential, high-capacity, and electronic conductivity can alloy with Li spontaneously and is proposed herein as a carbon-free and binder-free anode of an all-solid-state Li-S battery (LSB). A biphasic lithiation reaction of Al with modest volume change was revealed by in situ characterization. The Li0.8Al alloy anode showed excellent compatibility toward the Li10GeP2S12 (LGPS) electrolyte, as verified by the steady Li0.8Al-LGPS-Li0.8Al cell operation for over 2500 hours at 0.5 mA cm-2. An all-solid-state LSB comprising Li0.8Al alloy anode and melting-coated S composite cathode functioned steadily for over 200 cycles with a capacity retention of 93.29%. Furthermore, a Li-S full cell with a low negative-to-positive ratio of 1.125 delivered a specific energy of 541 Wh kg-1. This work provides an applicable anode selection for all-solid-state LSBs and promotes their practical procedure.