Stress-Dissipating Cocontinuous Carbon–Silicon Microparticles for High-Energy Lithium-Ion Batteries with Low Expansions

Large lithiation-induced expansion impedes the application of silicon anodes in lithium-ion batteries (LIBs). Although porous particles alleviate expansion, increasing structural fragility and specific surface area (SSA) negate cell performance. Here, we report structurally robust, low-SSA (5.2 m2/g) microparticles with cocontinuous carbon–silicon architecture (C–CSi). This design features a 3D interpenetrating nanosilicon and porous carbon network, encapsulated within micrometer-sized particles. As opposed to conventional carbon–silicon microparticles with discrete Si distribution, the continuous structure disperses lithiation stress and facilitates intraparticle Li diffusion, enabling high initial Coulombic efficiency (88.4%), and large calendaring compatibility (>1.4 g/cm3). Particle-specific tracking, finite element simulations, and operando Raman spectroscopy reveal stress dissipation and electrolyte isolation. The C–CSi/graphite || NCM811 pouch cells (4 mAh/cm2) showed >80% capacity over 300 cycles with minimal expansion comparable to graphite, and the stacked pouch cells achieve 330 Wh/kg. This work presents a novel carbon–silicon architecture for high-energy LIBs with minimized expansion.