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

Abstract

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)₃·9H₂O 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.