Sandwich-structured Fe3O4/Graphene Hybrid Film for High-Performance Lithium-Ion Batteries

Sandwich-structured Fe3O4/graphene hybrid film (FGHF) was prepared by electrostatic self-assembly and vacuum filtration. In the constructed architecture, the graphene sheets stacked densely in a nearly face-to-face fashion, while the Fe3O4 nanoparticles are homogeneously loaded on graphene nanosheets in a layer-by-layer manner. In this structure, the graphene sheets are supposed to provide high electronic conductivity, accommodate the volume fluctuation of Fe3O4, and improve flexibility of the electrode. Moreover, the FGHF exhibited a high surface area and hierarchical pore distribution, which are considered to be beneficial for fast ion transportation, short solid-state diffusion lengths and buffering volume expansion. As expected, the FGHF exhibited high lithium storage capacity (947 mAh g-1 at 1 A g-1), excellent rate capability (901, 806, 711 and 598 mAh g-1 at 2, 5, 10 and 20 A g-1, respectively) and stable cycle performance (798 mAh g-1 after 300 charge-discharge cycles at 1 A g-1).