Synthesis and characterization of bar-like maghemite (γ-Fe2O3) as an anode for Li-ion batteries

Abstract

In this study, bar-like maghemite (γ-Fe2O3) was obtained through the oxidation of lepidocrocite (γ-FeO(OH)) synthesized by the co-precipitation method. Afterward, the nano-bar γ-Fe2O3 performance as an anode for Li-ion batteries was studied. The formation of γ-FeO(OH) was confirmed by using Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) results declared the formation of γ-Fe2O3 as a single-phase after oxidation of γ-FeO(OH) at 200 °C for 2 h. Nitrogen adsorption-desorption (BET) and high-resolution transmission microscopy (HRTEM) results revealed the formation of bar-like maghemite with a high surface area (110 m2 g−1) and an average width of about 10 nm. The anode body was prepared by tape casting of a paste prepared of bar-like maghemite. Cyclic voltammetry results disclosed the reaction path of lithium and iron oxide through charging and discharging. In addition, galvanostatic charge-discharge cycling at a current density of 500 mA g−1 presented a reversible capacity of approximately 680 mAh g−1 after 50 cycles. Moreover, the cell showed acceptable stability even at the high current charge-discharge rates of 3000 mA g−1. The good performance of the anode can be due to the size and shape of the maghemite particles. Bar-like shapes ease the expansion and contraction of particles in two-direction with less destruction imposed.