Hierarchical sandwiched Fe₃O₄@C/Graphene composite as anode material for lithium-ion batteries

A three-dimensional hierarchical sandwich structured Fe₃O₄@C/Graphene nanocomposite was synthesized with a facile hydrothermal method, followed by carbonization process. The Fe₃O₄@C/Graphene nanocomposite consists of well-dispersed carbon enwrapped Fe₃O₄ nanoparticles anchored on graphene layers. The three-dimensional sandwich structure and the wrapping carbon effectively improve the mechanical stability and conductivity of encapsulated Fe₃O₄. The as-prepared Fe₃O₄@C/Graphene composite delivers a specific capacity of 1253.3 mAh g⁻¹ at the first cycle and 901.5 mAh g⁻¹ after 200 cycles at 200 mA g⁻¹. Even at 1500 mA g⁻¹, the Fe₃O₄@C/Graphene nanocomposite is able to deliver a discharge capacity of 592.3 mAh g⁻¹. The good cycle and rate performance of Fe₃O₄@C/Graphene anode can be attributed to its micro−/mesoporous structure with large specific surface area, which not only provides more transmission paths and active sites, but also reduces the diffusion impedance in electrolyte to realize fast transport of Li ions.