Sandwich-structured nanocomposites of N-doped graphene and nearly monodisperse Fe3O4 nanoparticles as high-performance Li-ion battery anodes

摘要

Iron oxides have attracted considerable interest as abundant materials for high-capacity Li-ion battery anodes.However,their fast capacity fading owing to poorly controlled reversibility of the conversion reactions greatly hinders their application.Here,a sandwich-structured nanocomposite of N-doped graphene and nearly monodisperse Fe3O4 nanoparticles were developed as high-performance Li-ion battery anode.N-doped graphene serves as a conducting framework for the self-assembled structure and controls Fe3O4 nucleation through the interaction of N dopants,surfactant molecules,and iron precursors.Fe3O4 nanoparticles were well dispersed with a uniform diameter of ～15 rn.The unique sandwich structure enables good electron conductivity and Li-ion accessibility and accommodates a large volume change.Hence,it delivers good cycling reversibility and rate performance with a capacity of ～1,227 mA.h.g-1 and 96.8％ capacity retention over 1,000 cycles at a current density of 3 A.g-1.Our work provides an ideal structure design for conversion anodes or other electrode materials requiring a large volume change.