Etching‐free synthesis of yolk–shell silicon microparticle@carbon composites for lithium‐ion batteries

Yolk–shell architectures mitigate silicon's severe volume expansion, yet complex, multi‐step etching remains a manufacturing hurdle. We report etching‐free synthesis for yolk–shell silicon microparticle@carbon (Si@V@G) composites using thermally decomposable poly(methyl methacrylate) (PMMA) as a sacrificial spacer. The approach synergizes chemical vapor deposition (CVD)‐induced graphitization with structural void engineering. CVD graphitization enhances electrical conductivity and effectively “seals” carbon micropores, reducing the specific surface area from 335.7–4 m 2 g −1 . This reduction suppresses parasitic electrolyte reactions, significantly boosting initial Coulombic efficiency (ICE). A voltage cut‐off optimization strategy matches lithiation depth with the available internal void volume. At a 0.05 V cut‐off, the optimized Si@V45@G electrode achieved an ICE of 84.7%, a discharge capacity exceeding 1290 mAh g −1 , and 98.2% capacity retention after 50 cycles at 0.5C. This work establishes an etching‐free design principle that decouples void formation from corrosive post‐treatment and highlights the importance of jointly optimizing structural buffering and electrochemical lithiation depth.