Effects of Carbon Precursors on LiFePO₄/C Nanocomposites for Lithium-Ion Batteries

Here we report the synthesis of LiFePO₄/C nanocomposite cathode materials for lithium ion batteries using a novel solution-based technique. Our technique is a modified version of traditional sol–gel technique and utilizes chelating agents which simultaneously create a coating of carbon on the LiFePO₄ nanoparticles. Two different chelating agents namely, poly vinyl alcohol (PVA) and citric acid were investigated. Different amounts of chelating agent were used in the starting solution to give different ratios of LiFePO₄ to Carbon in the final product. Materials thus synthesized were thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectrometer (FTIR), Raman spectroscopy, and electrochemical measurements. We find that chelating agents with short carbon chains (such as citric acid) performs better than agents with long carbon chains (such as PVA), and the carbon/lithium atomic ratios in the starting solution are optimized to be between 4:2 and 6:2.