Enhanced electrochemical performance of graphene modified LiFePO4 cathode material for lithium ion batteries

We report the synthesis of LiFePO4/graphene nano-composites using sol–gel method in the presence of dispersed graphene oxide mixed with LiFePO4 precursors. The phase purity of the nano-LiFePO4/graphene composite was confirmed by X-ray diffraction. The electronic conductivity of LiFePO4/graphene composite was found to be six orders of magnitude higher than that of pure LiFePO4 synthesized following otherwise the same procedure without the addition of graphene. Scanning electron microscopy and transmission electron microscope images show LiFePO4 particles being covered uniformly by graphene sheets throughout the material forming a three-dimensional conducting network. At low currents and charging rate of C/3, the capacity of the composite cathode reaches 160 mAh/g, which is very close to the theoretical limit. More significantly, the LiFePO4–graphene composite shows a dramatically improved rate capability up to 27 C and excellent charge–discharge cycle stability over 500 stable cycles in comparison with the LiFePO4 without graphene.