Facile synthesis of laminate-structured graphene sheet–Fe3O4 nanocomposites with superior high reversible specific capacity and cyclic stability for lithium-ion batteries

Abstract

A facile one pot hydrothermal method has been developed to synthesize laminate-structured graphene sheet–Fe₃O₄ nanocomposites (GNS–Fe₃O₄). Fe₃O₄ nanoparticles were decorated densely and homogeneously in the graphene matrix. Galvanostatic charge–discharge cycling of the GNS–Fe₃O₄ nanocomposites exhibited a reversible specific capacity over 1200 mAh g⁻¹ at 100 mA g⁻¹ without palpable fading for 50 cycles in the voltage range 0.01–3.0 V. A cell for the rate capacity test indicated a high current density of 946 mAh g⁻¹ at a cycling rate of 1000 mA g⁻¹, which could be fully recovered to 1359 mAh g⁻¹ at 100 mA g⁻¹ after 50 cycles. The superior electrochemical performance of the nanocomposites can be attributed to the following factors: (i) the thermal expanded graphene oxide (TEGO) under atmosphere could attach more oxygen functional groups than the hydrogen reduced graphene, which benefited the adsorption and fastness of the nano-sized Fe₃O₄; (ii) annealing of TEGO–Fe₃O₄ nanocomposites further improved the conductivity of the graphene matrix, providing a high electron transport rate at the electrode–electrolyte interface; (iii) the laminated structure of nanocomposites could prevent the agglomeration of Fe₃O₄ nanoparticles and the restacking of graphene sheets, and effectively release the strain caused by the volume expansion of the Fe₃O₄ nanoparticles, facilitating ion/electron transportation within the electrode and at the electrode–electrolyte interface.