Preparation and Electrochemical Properties of LiFePO<sub>4</sub>/PPy Composite Cathode Materials for Lithium-Ion Batteries

LiFePO4/PPy composites with different content of polypyrrole (PPy) were prepared by chemical oxidation reactions. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the LiFePO4/PPy composite. The results showed that doped PPy did not destroy the olivine structure of LiFePO4 but decreased the intensity of the diffraction peaks, and PPy was found on the surface of LiFePO4 particles. PPy could remarkably increase the conductivity of the composite and improve the electrochemical performance of LiFePO4. The sample with 2.5 % (wt). PPy possessed a high initial discharge capacity of 144.5mAh/g at 0.1C. The results of both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) proved good cycle performances of the samples doped by PPy.