The Alternating Stress Evolution and Buffering Effects in All‐Solid‐State Lithium–Sulfur Battery with Pre‐Lithiated Silicon‐Based Anode

Sulfide‐based all‐solid‐state lithium‐sulfur batteries (ASSLSBs) hold immense promise for next‐generation energy‐storage due to their high theoretical energy density and enhanced safety. However, fatigue issues such as electrolyte cracking and interfacial damage caused by big volume changes of both electrodes and mechanical stress remain critical challenges. Herein, the distinct alternative against monotonical stress evolution is first analyzed in ASSLSBs employing pre‐lithiated silicon‐based anodes versus conventional lithium metal by using in‐situ pressure‐detection techniques. Notably, the pre‐lithiated silicon‐based system demonstrates an alternating stress dominance pattern that effectively stabilizes mechanical responses through stress cancellation effects. Moreover, the investigation shows that the stress‐buffering effect of pre‐lithiated silicon‐based stems from the phase transition dynamics of intermediate Li21Si5 during lithiation. The finite element modeling and micro‐structural morphology analysis is employed to link phase transformation kinetics directly to mechanical stress modulation. This unique characteristic proves crucial in suppressing crack propagation within electrolytes while maintaining stable electrode/electrolyte interfaces. Consequently, the full‐cell using pre‐lithiated silicon‐based achieves stable cycling performance with high S loading (4.5 mg cm−2) at 0.5C (∼3.6 mA cm−2), which outperforms conventional solid‐state lithium‐sulfur batteries. The discovered chemo‐mechanical coupling principles provide new insights for developing high‐stability ASSLSBs, particularly in mitigating interfacial degradation induced by large volume changes.