Electrochemical performance of Mo-doped LiFePO4/C composites prepared by two-step solid-state reaction

摘要

To improve the performance of LiFePO4, LiFe_(1-x)Mo_xPO4/C (x=0,0.005,0.010,0.015,0.020,0.025) cathode materials were synthesized via two-step ball milling solid-state reaction. The prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectra, and galvanostatic charge-discharge test. It is apparent from XRD analysis that Mo doping enlarges the interplanar distance of crystal plane parallel to [010] direction in LiFePO4. In other words, it widens one-dimensional diffusion channels of Li~+ along the [010] direction. The results of electrochemical test indicate that the LiFe_(0.99)Mo_(0.01)PO4/C composite exhibits a discharge capacity of 144.8 mAh g~(-1) at 1 C rate, a decreased charge transfer resistance of 162.4 Ω and better reversibility of electrode reactions. The present synthesis route is promising and practical for the preparation of LiFePO4 materials.