A core-shell Si@SiO₂@NC (N-doped carbon) composite material is proposed for improving the performance of silicon-based lithium-ion battery resulting from the volume expansion and poor conductivity of Si during the charge and discharge processes. SiO₂ layer is prepared by treating the surface of Si nanoparticles with oxygen plasma, and N-doped amorphous carbon is obtained by carbonizing the polyaniline coating. The SiO₂ interlayer has a reliable buffer effect and good mechanical support to restrain the volume expansion of Si nanoparticles during charge and discharge processes, and N-doped amorphous carbon can serve as a fast transport channel for electrons and Li⁺. Compared with Si nanoparticles, Si@SiO₂@NC composites show a high initial discharge capacity of 2 583.1 mAh/g with Coulombic efficiency of 81% as well as a high reversible capacity of 1 015 mAh/g at a current density of 200 mA/g after 40 cycles.