One-step solvothermal preparation of Fe3O4/graphene composites at elevated temperature and their application as anode materials for lithium-ion batteries

Abstract

A one-step high-temperature solvothermal process (can be used up to 400 °C) has been explored for the preparation of Fe₃O₄/graphene composites. The influence of high temperature (>230 °C) on the structure, morphology and electrochemical properties of the resulting Fe₃O₄/graphene composites was investigated by XRD, SEM, TEM and N₂ adsorption–desorption measurements. Electrochemical performances of the as-prepared Fe₃O₄/graphene composites at different temperatures were evaluated in coin-type cells as anode materials for lithium-ion batteries. In comparison with the traditional solvothermal method (<240 °C), the high-temperature method does not require an additional calcination process yet it still could result in Fe₃O₄/graphene composites with pure phase and excellent electrochemical properties. A preferred solvothermal temperature of 280 °C has been deduced based on a series of control experiments. The Fe₃O₄/graphene composite derived at 280 °C exhibited a high reversible capacity of 907 mA h g⁻¹ at 0.1 C (92.6 mA g⁻¹) even after 65 cycles, showing outstanding cycle stability. It also exhibited a high rate capability of 410 mA h g⁻¹ at 2 C (1852 mA g⁻¹). The role of the graphene substrates in improving the electrochemical properties of the composite is discussed based on the morphology, structure, phase and electrochemical property studies.