Preparation and electrochemical properties of LiFePO4/C nanocomposite using FePO4·2H2O nanoparticles by introduction of Fe3(PO4)2·8H2O at low cost

A LiFePO4/C composite was synthesized by a simple solid-state reaction method using stearic acid as reductive agent and carbon source and nano-sized FePO4·2H2O as precursor which was prepared from intermediate Fe3(PO4)2·8H2O using industrial FeSO4·7H2O and industrial NH4H2PO4 at a low cost. The structure, morphology and electrochemical performance of LiFePO4/C were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge-discharge tests, cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that the LiFePO4/C has an olivine-type structure with nano-size and exhibits excellent electrochemical properties. The discharge capacities are 159 mAh g−1, 148 mAh g−1 and 113 mAh g−1 at 0.1 C, 1 C and 10 C, respectively. Furthermore, the capacity retention rate is higher than 99% after 100 cycles at 1 C and 10 C. The excellent electrochemical performances of LiFePO4/C composite should be attributed to spherical nanoparticles as well as less impurity in FePO4·2H2O precursor.