Elastic Ion-Conducting Layer Enables Stable Si-Based All-Solid-State Batteries

Si-based all-solid-state batteries with sulfide solid electrolytes are strong contenders for next-generation high-safety, high-energy-density batteries. However, Si-based anodes inevitably suffer from irreversible delamination and side reactions at the rigid Si/solid electrolyte interface during cycling, making it challenging to achieve long cycle life. Here, we develop an elastic ion-conducting layer on the Si surface that transforms the rigid interface into a conformal and recoverable elastic contact, achieving highly stable Si anode. The layer comprises a lithium bis(fluorosulfonyl)imide-containing block copolymer, whose hydrogen-bond-rich hard domains provide mechanical robustness and elasticity. Ion-conductive soft segments, together with an in situ-formed inorganic-rich solid electrolyte interphase on the Si surface, construct a three-dimensional ion transport network. This interfacial architecture simultaneously mitigates interfacial stress and accelerates lithium-ion transport within the Si anode. Consequently, the full-cell exhibits stable cycling over 10,000 cycles at a high rate of 5C (8.7 mA cm^-2), and the 0.6 Ah pouch cell retains 91% capacity after 650 cycles. Such interfacial layer holds great promise for accelerating the commercialization of Si-based all-solid-state batteries.