Electrochemical Properties of xLiFePO4·yLi3V2(PO4)3/C Nanosized Composite Cathode Materials Prepared by Solid Reaction Method

In this paper, a series of xLiFePO4·yLi3V2(PO4)3/C (x/y = 1:0, 7:1, 5:1, 3:1, 1:1, 1:3 and 0:1, ratio of mol) nanosized composite cathode materials were prepared by solid reaction method. Influence of x/y ratio on the composition, microstructure and electrochemical properties of the materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical measurements, et al. XRD patterns showed that most of iron (Fe) and vanadium (V) in raw materials tended to form the LiFePO4 and Li3V2(PO4)3 phases, while small amounts of them were as the dopant and entered into the lattice of Li3V2(PO4)3 and LiFePO4, respectively. TEM images exhibited that the 7LiFePO4·Li3V2(PO4)3/C composite shows good dispersion and the size ranging in 50-150 nm, which was coated uniformly with the carbon layer. The value of the first discharge specific capacity of the composites was 145.6 mAh/g and its capacity retention was 99.8% after 50 cycles at 0.1 C. Compared with the single LiFePO4 and Li3V2(PO4)3, its cycle performance was also remarkable improved.