Reaction mechanism and electrochemical performance of LiFePO4/C cathode materials synthesized by carbothermal method

Spray drying and carbothermal method was employed to investigate reaction mechanism and electrochemical performance of LiFePO₄/C cathode by using different carbon sources. Micro-structural variations of LiFePO₄/C precursors using different carbon sources were studied by Thermo-gravimetric (TG)/Differential Thermal Analysis (DTA). The LiFePO₄/C samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) absorption spectroscopy. The results indicated that the crystallization temperature of LiFePO₄ was 453 °C, while the transform temperature was 539 °C from Li₃Fe₂(PO₄)₃ to LiFePO₄. At 840 °C, LiFePO₄/C sample with an excess of impurity phase Fe₂P gave much poorer electrochemical performance. The severe decomposition of LiFePO₄/C happened at 938 °C and generated impurity phases Li₄P₂O₇ and Fe₂P. The clear discharge platform of Fe₂P emerged at around 2.2 V.