Preparation and electrochemical properties of a LiFePO4/C composite cathode material by a polymer-pyrolysis-reduction method

A LiFePO4/C composite was successfully prepared by a polymer-pyrolysis-reduction method, using FePO4.2H2O and lithium polyacrylate (PAALi) as raw materials. The structure of the LiFePO4/C composites was investigated by X-ray diffraction (XRD). The micromorphology of the precursor and LiFePO4/C powders was observed using scanning electron microscopy (SEM), and the in situ coating of carbon on the particles was observed by transmission electron microscopy (TEM). Furthermore, the electrochemical properties were evaluated by cyclic voltammograms (CVs), electrochemical impedance spectra (EIS) and constant current charge/discharge cycling tests. The results showed that the sample synthesized at 700 oC had the best electrochemical performance, exhibiting initial discharge capacities of 157, 139 and 109 mAh g-1 at rates of 0.1, 1 and 5 C, respectively. Moreover, the sample presented excellent capacity retention as there was no significant capacity fade after 50 cycles.