Effect of carbon sources on the electrochemical performance of Li2FeSiO4 cathode materials for lithium ion batteries

Li₂FeSiO₄ cathode materials have been prepared by sol-gel method. The effects of carbon sources on the structural, morphological and electrochemical behaviors of Li₂FeSiO₄ were investigated. The scanning electronic microscope (SEM) and X-ray diffraction powder analysis (XRD) indicate that the obtained samples using different carbon sources possess some difference in the morphology and in the particle size. The sample using the mixture of citric acid and oxalic acid as carbon source has a maximum discharge capacity of 118 mA h g^?1 at 0.1 C between 1.8 and 4.5 V. The resulting cyclic voltammograms and electrochemical impedance spectra suggest that the sample using mixed acid as carbon source has smaller polarization and smaller charge transfer impedance.