SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF Li2FeSiO4/C AS CATHODE MATERIALS FOR LITHIUM-ION BATTERIES

Li2FeSiO4/C composites have been successfully prepared by a combination of solution route and high-temperature solid-state reaction processes. The morphology and crystalline structure were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD). Effects of calcination temperature on the electrochemical properties of Li2FeSiO4/C composite cathodes were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance measurements. The XRD patterns indicate that high-purity Li2FeSiO4 with well-developed crystallinity are obtained above 600 degrees C. The primary particle size was increased by elevating the calcination temperature from 600 degrees C to 750 degrees C. The Li2FeSiO4/C composite synthesized at 650 degrees C delivers the largest initial discharge capacity of 153.2 mAh g(-1) with a capacity retention of 93.5% after 30 cycles when tested at a current density of C/16 (1C = 166 mAh g(-1)) between 1.5 and 4.8 V (vs. Li+/Li).