Synthesis and electrochemical performance of Li2FeSiO4/C as cathode material for lithium batteries

Li2FeSiO4/C cathode material was synthesized by a traditional solid-state reaction method with Li2CO3, FeC2O4·2H2O, nano SiO2 as starting materials and pitch as the carbon source. For comparison, the Li2FeSiO4/C with glucose as the carbon source and the pristine Li2FeSiO4 were also prepared. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy, elementary analyzer, BET specific surface area, galvanostatic charge-discharge test and AC impedance spectroscopy. The results demonstrated that the Li2FeSiO4/C composites showed better electrochemical properties compared with the pristine Li2FeSiO4. Surprisingly, the Li2FeSiO4/C with pitch as carbon source exhibited the best electrochemical properties among the three samples, it delivered a specific discharge capacity of 139 mAh g−1, 127 mAh g−1, 118 mAh g−1 and 103 mAh g−1 at 0.2 C, 0.5 C, 1 C and 2 C, respectively. After 100 cycles at the rate of 1 C, the discharge capacity remained 93.6% of its initial value.