Synthesis and characterization of LiFePO₄/(C + Fe₂P) composite cathodes

LiFePO₄/(C + Fe₂P) composite cathode with composite conductive webs structure was synthesized by modified carbothermal reduction method from the amorphous gel precursor at a heat-treatment temperature of 700 °C. The composite material exhibits an improved discharge capacity. Discharge capacities at 1 C rate were improved from 121.4 mAh g^{- 1} of LiFePO₄/C to 140.8 mAh g^{- 1} of LiFePO₄/(C + Fe₂P) composite materials synthesized by two different routes using the same gel precursor, which could be, at least in part, attributed to the improved conductivity through the in situ formed Fe₂P phase by the method. Electrochemical impedance measurements show that coexistence of the carbon and Fe₂P phase with LiFePO₄ could decrease the charge transfer resistance and increase surface electronic conductivity of the LiFePO₄/(C + Fe₂P) composite cathode.