In-Situ Construction of a Highly Resilient Artificial SEI for Low-Expansion Silicon Oxide Anodes

Silicon oxide (SiO_x/C) anodes are fundamentally limited by large volume change and repeated fracture of the solid electrolyte interphase (SEI), which lead to continuous electrolyte decomposition and rapid lithium (Li) inventory loss. Here, we introduce a lithium maleate derived unsaturated precursor to in-situ build a highly resilient artificial SEI (ASEI). The precursor is compatible with slurry processing and undergoes early-cycle interfacial reactions, forming a conformal and mechanically robust interphase. Benefiting from this resilient ASEI, the SiO_x/C@ASEI anode shows negligible capacity fade at 1 A/g, sustains high-areal-capacity operation (~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 full cells. Post-mortem analyses directly verify a low expansion electrode behavior (2.5% vs 61.4% swelling) with suppressed cracking, together with a thinner, more 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 work offers a scalable route toward low-swelling SiO_x-based anodes for high-energy Li-ion batteries.