Synthesis and electrochemical properties of LiFe0.95VxNi0.05−xPO4/C cathode material for lithium-ion battery

In this study, crystalline LiFe0.95VxNi0.05−xPO4/C powders are successfully synthesized using the hydrothermal method. Materials characterization and the electrochemical performance of LiFe0.95VxNi0.05−xPO4/C are investigated. The structure, morphology, and electrochemical performances of the prepared samples are investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry, and AC impedance. The XRD pattern indicates that the LiFe0.95VxNi0.05−xPO4/C powders are single-phased with an orthorhombic olivine structure. The LiFe0.95V0.05PO4 sample has the highest capacity of 141 mAh g−1, which is 6% higher than that of pure LiFePO4 at 0.1 C. As the discharge rate increases to 10 C, the LiFe0.95V0.04Ni0.01PO4 sample has the highest capacity of 100 mAh g−1, which is 18% higher than that of pure LiFePO4. The CV results prove that the LiFe0.95V0.04Ni0.01PO4 cathode has high capacity and good cyclic performance caused by the high lithium-ion diffusion transport, which is improved by Ni and V doping.