Synergistic Ternary Composite (Carbon/Fe3O4@Graphene) with Hollow Microspherical and Robust Structure for Li‐Ion Storage

The electrode materials with hollow structure and/or graphene coating are expected to exhibit outstanding electrochemical performances in energy‐storage systems. 2D graphene‐wrapped hollow C/Fe₃O₄ microspheres are rationally designed and fabricated by a novel facile and scalable strategy. The core@double‐shell structure SPS@FeOOH@GO (SPS: sulfonated polystyrene, GO: graphene oxide) microspheres are first prepared through a simple one‐pot approach and then transformed into C/Fe₃O₄@G (G: graphene) after calcination at 500 °C in Ar. During calcination, the Kirkendall effect resulting from the diffusion/reaction of SPS‐derived carbon and FeOOH leads to the formation of hollow structure carbon with Fe₃O₄ nanoparticles embedded in it. In the rationally constructed architecture of C/Fe₃O₄@G, the strongly coupled C/Fe₃O₄ hollow microspheres are further anchored onto 2D graphene networks, achieving a strong synergetic effect between carbon, Fe₃O₄, and graphene. As an anode material of Li‐ion batteries (LIBs), C/Fe₃O₄@G manifests a high reversible capacity, excellent rate behavior, and outstanding long‐term cycling performance (1208 mAh g^?1 after 200 cycles at 100 mA g^?1).