Synergistic Interfacial Confinement and CVD-Derived Graphene Encapsulation in Silicon/Reduced Graphene Oxide/Graphene Composite for High-Performance Si Anodes

Silicon (Si)-based anodes are promising for next-generation lithium-ion batteries but suffer from severe volume expansion, structural degradation, and unstable interphase during cycling. Herein, a synergistic oxidation and controllable assembly strategy are proposed. First, Si nanoparticles (SiNPs) are co-oxidized with graphite, during which the SiOx layer formed on the SiNP surface chemically bonds with the oxygen-containing functional groups of graphene oxide (GO) nanosheets. This interaction integrates SiNPs into the three-dimensional (3D) GO network via intercalation, wrapping, and anchoring, yielding a hierarchically encapsulated Si/GO precursor. Subsequently, chemical vapor deposition (CVD) is conducted to grow an outer graphene shell in situ on the Si/GO precursor, ultimately producing the Si/rGO/Gr composite. In this architecture, the 3D GO network provides multilevel buffering spaces, while the outer graphene layer serves as a conductive and mechanical confinement sheath, synergistically mitigating Si expansion and facilitating charge transfer. The optimized Si/rGO/Gr anode delivers reversible capacities of 1104.6 and 678.2 mAh g−1 at 0.05 and 1 A g−1, respectively. When assembled into a full cell with a LiFePO4 cathode, the Si/rGO/Gr anode exhibits reversible capacities of 149.0 and 113.2 mAh g−1 at 0.5 and 5 C, respectively. This work demonstrates that the combination of synergistic oxidation, controllable assembly, and CVD graphene encapsulation offers a viable synthetic route toward high-stability Si-based anodes.