Improving rate performance of LiFePO4 cathode materials by hybrid coating of nano-Li3PO4 and carbon

• This paper reports an improved solid-state method which leads to a uniform coating. The influence of Li3PO4 and carbon coating on the electrochemical performance of LiFePO4 was studied.
• LiFePO4 coating with Li3PO4 and carbon shows a higher capacity than pure carbon coating sample.
• Results indicate that the surface structure has an important influence on the electrochemical performance of LiFePO4. The addition of Li3PO4 can decrease the interfacial resistance of Li FePO4.

Li3PO4 coating on the surface of LiFePO4 particles was prepared by direct dispersing LiFePO4 precursor in starch slurry with nano-Li3PO4. The existence of nano-Li3PO4 was confirmed with X-ray powder diffraction (XRD). And the particle size and morphology were observed by scanning electron microscope (SEM) and transmission electron microscope analysis (TEM). The effects of the mixture coating on rate performance of LiFePO4 cathode vs Li anode at 25 °C was investigated. Li3PO4 and carbon mixing coated LiFePO4 cathode materials exhibited markedly improved rate capability relative to bare carbon-coated LiFePO4. Analyses on cell impedance showed that the Li3PO4 coating decreased the interfacial impedance. Transmission electron microscope analysis, electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV) were carried out to explain the reason of better rate performance by Li3PO4 coating.

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