In situ construction of highly resilient artificial solid electrolyte interphase for low-expansion silicon oxide anodes

Silicon oxide (SiO_x/C) anodes are fundamentally limited by large volume variations and repeated fracture of the solid electrolyte interphase (SEI), leading to continuous electrolyte decomposition and rapid loss of lithium (Li) inventory. Herein, we introduce a lithium maleate-derived unsaturated precursor to construct a highly resilient artificial SEI (ASEI) in situ. The precursor is compatible with slurry processing and undergoes interfacial reactions during the initial cycles, forming a conformal and mechanically robust interphase. Enabled by this resilient ASEI, the SiO_x/C@ASEI anode shows negligible capacity decay at 1 A g⁻¹, maintains stable cycling under a high areal capacity (~3.1 mAh cm⁻²) for 500 cycles, and improves the cycling stability of SiO_x/C@ASEI||LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) full cells. Postmortem analyses directly verified reduced electrode expansion (2.5% vs. 61.4% swelling), suppressed cracking, the formation of a thin and uniform SEI (19.2 vs. 31.4 nm), and mitigated electrolyte decomposition. By decoupling SiO_x volume variation from repetitive interfacial reconstruction through a resilient ASEI, this study offers a scalable strategy for developing low-swelling SiO_x-based anodes for high-energy Li-ion batteries.