Synthesis of Carbon-coated LaFeO3 and Electrochemical Properties of the Composites in Alkaline Solution

LaFeO3 nanostructure powders oxide was synthesized by sol-gel method and then LaFeO3/C composite materials containing different amounts of carbon were prepared by heat treatment using sucrose as a carbon source. The crystal structure, surface morphologies and electrochemical properties of the obtained composites coated with various carbon contents were investigated by the techniques of XRD, SEM, TEM, Raman spectroscope and electrochemical method. It was found that single phase nanostructure with perovskite-type LaFeO3 was obtained by Sol-Gel method and the crystal structure of LaFeO3/C could not be changed after coating carbon. Under high temperature, sourose was decomposed into amorphous carbon, which coated on the surface of LaFeO3 particles and formed network-like structure between LaFeO3 particles. Electrochemical measurements showed that the carbon- coated composites were superior in the electrochemical performance to the LaFeO3. LaFeO3/C electrodes possessed high discharge capacities, among which the sample adding with 5wt% carbon had the largest discharge capacity of 390 mAh/g. With increasing amount of carbon coated, the exchange current density I0 significantly enhanced, while effect of the coated carbon on the diffusion coefficient of ions was not obvious.