3D graphene-encapsulated nearly monodisperse Fe3O4 nanoparticles as high-performance lithium-ion battery anodes

A facile self-assembly strategy is developed to construct three-dimensional graphene-encapsulated nearly monodisperse Fe3O4 (3D Fe3O4@rGO) composite. The nearly monodisperse Fe3O4 nanoparticles (NPs) are intimately wrapped by the flexible 3D rGO network that can remarkable increase the electrochemical utilization of Fe3O4. 3D Fe3O4@rGO composite indicates excellent electrochemical properties as lithium-ion battery anodes. The void holes between flexible rGO nanosheets and Fe3O4 NPs can not only act as the electrolyte reservoir to tremendously shorten the Li+ diffusion distance, but also provide extra accommodating space for fast Li+ insertion and extraction. A reversible discharge specific capacity of 1139 mA h g−1 and 85% capacity retention can achieve at a current density of 400 mA g−1 after 100 cycles. More impressively, 3D graphene-encapsulated Fe3O4 exhibits a high lithium storage capacity of 665 mA h g−1 at 1000 mA g−1 after 200 cycles, demonstrating the excellent lithium storage performance.