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 Li_0.8Al alloy anode showed excellent compatibility toward the Li₁₀GeP₂S₁₂ (LGPS) electrolyte, as verified by the steady Li_0.8Al-LGPS-Li_0.8Al cell operation for over 2500 hours at 0.5 mA cm^-2. An all-solid-state LSB comprising Li_0.8Al 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.