Enhanced Electrochemical Performances of LiFePO4/C via V and F Co-doping for Lithium-Ion Batteries

Based on the method of in situ polymerization synthesis combined with two-step sintering process, LiFe1−xVx(PO4)(3−y)/3Fy/C was prepared. The effects of V and F co-doping on the structure, morphology, and electrochemical performances of LiFePO4/C were investigated by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscope, charge/discharge tests, and electrochemical impedance spectroscopy, respectively. The results indicated that the V and F co-doping did not destroy the olivine structure of LiFePO4/C, but it can stabilize the crystal structure, decrease charge transfer resistance, enhance Li ion diffusion velocity, further improve its cycling and high-rate capabilities of LiFePO4/C.