Preparation and characteristics of Li2FeSiO4/C composite for cathode of lithium ion batteries

A Li2FeSiO4/C composite cathode for lithium ion batteries was synthesized at 650 °C by solid-state reaction. The effects of carbon sources and carbon content on the properties of the Li2FeSiO4/C composites were investigated. The crystalline structure, morphology, carbon content and charge/discharge performance of Li2FeSiO4/C composites were determined by X-ray diffraction(XRD), scanning electron microscopy(SEM), carbon/sulfur analyzer and electrochemical measurements. As carbon content increases in the range of 5%–20%, the amount of Fe3O4 impurity phase decreases. The SEM micrographs show that the addition of the carbon is favorable for reducing the Li2FeSiO4 grain size. Using sucrose as carbon source, the Li2FeSiO4/C composite with 14.5% carbon synthesized at 650 °C shows good electrochemical performance with an initial discharge capacity of 144.8 mA·h/g and a capacity retention ratio of 94.27% after 13 cycles.