▎ 摘　　要

Graphene encapsulated Fe3O4 nanospindles were synthesized by a simple hydrothermal method. From field-emission and transmission electron microscopy results, the Fe3O4 nanospindles with the length of about 260 nm are highly encapsulated in graphene matrix. The reversible Li-cycling properties of graphene encapsulated Fe3O4 nanospindles have been evaluated by galvanostatic discharge-charge cycling and cyclic voltammetry. Results show that graphene encapsulated Fe3O4 nanospindles exhibits a high reversible capacity about 745 mA h g(-1) for the first cycle and a stable capacity of about 558 mA h g(-1) for up to 200th cycle in the voltage range of 0.01-3.0 V at a current density of 100 mA g(-1), indicating excellent cycling stability. The graphene in the composite materials could act not only as lithium storage active materials, but also as an electronically conductive matrix to improve the electrochemical performance of Fe3O4.