Study on the Electrochemical Characteristics of Hydrothermally Prepared LiFePO_4 Followed by Carbon Coating

The olivine-type LiFePO4/C cathode materials were prepared via hydrothermal reaction using LiOH,FeSO4 and H3PO4 as raw materials and different contents of glucose as the carbon source.The samples were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),constant current charge-discharge cycling test and and electrochemical impedance spectroscopy(EIS).The results indicate that carbon adding improves the capacity,cycle stability and lithium ion diffusion kinetics of LiFePO4.Electrochemical tests show that the discharge capacity first increases and then decreases with the increase of carbon content.The optimal sample LiFePO4/C with 3wt% carbon exhibites the highest discharge capacity of 145mAh/g at 0.1C rate,142mAh/g at 0.2C rate,after 50 cycles,capacity fade was only 0.7%.