High-performance all-solid-state Li–S batteries enabled by an all-electrochem-active prelithiated Si anode

The development of all-solid-state Li–S batteries has been greatly impeded by dendrite growth and dendrite penetration, which are both related to the Li metal anode. As a compromised alternative, we report lithium silicide (Li_xSi) as a dendrite-free and high-capacity anode with Li source. The as-synthesized Li_xSi is relatively soft, highly electronically conductive, and with a high Li diffusivity. These distinctive properties make Li_xSi anode viable as an “all-electrochem-active” electrode (consisted of 100 wt.% Li_xSi). Compared with the typical composite electrode, the all-electrochem-active electrode not merely maximizes the electrode-level energy density but also minimizes the electrolyte-related interfacial degradation. Li_xSi symmetric cell demonstrates a reversible cycling at 4 mA cm^–2 for over 320 h. Stress change and morphological evolution of the Li_xSi electrode are investigated upon dealloying/alloying. When paired with a S cathode (active mass loading of 3 mg cm^–2), Li_xSi–S full cell shows a good cycling behavior over 500 cycles and rate performance (69% capacity retained at 1.2C) even at 25 °C.