Low-Temperature Synthesis of LiFePO4 Nanoplates/C Composite for Lithium Ion Batteries

The LiFePO4 nanoplates/C composite was synthesized by a low-temperature precipitation approach around 106 °C. X-ray powder diffraction refinement revealed a smaller crystallographic cell volume of this composite compared to stoichiometric LiFePO4, implying the presence of Li vacancies. Moreover, Mössbauer analysis evidenced Fe3+ with content as large as 26 at. %, which was related to amorphous ferric phase (LiFePO4(OH)) in the composite. A short low-temperature annealing under reducing condition can convert this amorphous phase to crystalline LiFePO4. This achieves significant improvement in the electrochemical performance of the LiFePO4/C composite with reversible discharge capacity of 142 mAh g–1 at C/20 and 82 mAh g–1 at 2 C, which are much higher than 105 and 49 mAh g–1 of the bare LiFePO4 at the same current rates, respectively.