Electrochemical and XPS study of LiFePO4 cathode nanocomposite with PPy/PEG conductive network

High performance PPy/PEG-LiFePO4 nanocomposites as cathode materials were synthesized by solvothermal method and simple chemical oxidative polymerization of pyrrole (Py) monomer on the surface of LiFePO4 particles. The samples were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectrometry (XPS) and charge-discharge tests. PPyPEG hybrid layers decrease particle to particle contact resistance while the impedance measurements confirmed that the coating of PPy-PEG significantly decreases the charge transfer resistance of the electrode material. The initial discharge capacities of this sample at C/5 and 1C are 150 and 128 mAh/g, respectively. The results show that PPy/PEGLiFePO4 composites are more effective than bare LiFePO4 as cathode material.

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► The initial discharge capacities of PPy/PEG-LiFePO4 at C/5 and 1C are 150 and 128 mA h/g, respectively.
► EIS results demonstrated that the polymer coating improves electronic conductivity of LiFePO4.
► XPS and SEM results confirmed that the LiFePO4 particles are homogeneously covered by PPy/PEG.