Magnetite/graphene nanosheet composites: interfacial interaction and its impact on the durable high-rate performance in lithium-ion batteries

We explore in-depth the interfacial interaction between Fe3O4 nanoparticles and graphene nanosheets as well as its impact on the electrochemical performance of Fe3O4/graphene anode materials for lithium-ion batteries. Fe3O4/graphene hybrid materials are prepared by direct pyrolysis of Fe(NO3)(3)center dot 9H(2)O on graphene sheets. The interfacial interaction between Fe3O4 and graphene nanosheets is investigated in detail by thermogravimetric and differential scanning calorimetry analysis, Raman spectrum, X-ray photoelectron energy spectrum and Fourier transform infrared spectroscopy. It was found that Fe3O4 nanoparticles disperse homogeneously on graphene sheets, and form strong covalent bond interactions (Fe-O-C bond) with graphene basal plane. The strong covalent links ensure the high specific capacity and long-period cyclic stability of Fe3O4/graphene hybrid electrodes for lithium-ion batteries at high current density. The capacity keeps as high as 796 mAhg(-1) after 200 cycles without any fading in comparison with the first reversible capacity at the current density of 500 mAg(-1) (ca. 0.6 C). At 1 Ag-1 (ca. 1.3 C), the reversible capacity attains ca. 550 mAhg(-1) and 97% of initial capacity is maintained after 300 cycles. This work reveals an important factor affecting the high-rate and cyclic stability of metal oxide anode, and provides an effective way to the design of new anode materials for lithium-ion batteries.