Microwave assisted synthesis of α-Fe2O3/reduced graphene oxide as anode material for high performance lithium ion batteries

Abstract

α-Fe₂O₃/reduced graphene oxide (RGO) nanocomposites were synthesized by a rapid and simple microwave method. Fe(OH)₃ sol was used as the precursor of α-Fe₂O₃. Upon microwave heating, graphene oxide (GO) was reduced to RGO using hydrazine hydrate as a reductant and Fe(OH)₃ sol transformed into α-Fe₂O₃ particles attached uniformly onto RGO surfaces at the same time. The structure, morphology and composition of α-Fe₂O₃/RGO nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis and Raman spectroscopy. Electrochemical characteristics were evaluated by coin-type cells versus metallic lithium and cyclic voltammetry. The prepared α-Fe₂O₃/RGO nanocomposites exhibited a high reversible specific capacity of 650 mA h g⁻¹ after 50 cycles at a current density of 1.0 A g⁻¹, showing more superior rate capability than both α-Fe₂O₃ nanoparticles and RGO sheets. At the larger current density of 10.0 A g⁻¹, the capacity of α-Fe₂O₃/RGO nanocomposites still remained 400 mA h g⁻¹. The significant improvements in the electrochemical properties of α-Fe₂O₃/RGO nanocomposites could be attributed to the uniform α-Fe₂O₃ nanoparticles (30–50 nm) on the RGO substrate, which provided high electrical conductivity, confined the position and buffered the volume changes of α-Fe₂O₃ nanoparticles.