Surface Oxidation Layer-Mediated Conformal Carbon Coating on Si Nanoparticles for Enhanced Lithium Storage

Si is a well-known high-capacity lithium-ion battery anode material; however, it suffers from conductivity and volume expansion issues. Herein, we develop a "surface oxidation" strategy to introduce a SiO layer on Si nanoparticles for subsequent carbon coating. It is found that the surface SiO layer could facilitate the conformal resin coating process through strong interactions with phenolic resin, and well-defined core@double-shell-structured Si@SiO@C can be obtained after further carbonization. Without the surface SiO layer, only a negligible fraction of Si nanoparticles can be encapsulated into the carbon matrix. With enhanced conductivity and confined volume change, Si@SiO@C demonstrates high reversible capacity as well as long-term durability.