Physical and Electrochemical Properties of LiFePO4/C Cathode Material Prepared from a New Carbon Source

LiFePO4/C cathode materials for lithium ion battery were prepared by solid-state method from using Polystyrene (PS) micro-spheres as new carbon source. The structure, morphology and electrochemical performances of LiFePO4/C were investigated by X-ray diffraction (XRD), scanning electronic morphology (SEM) and galvanostatic charge-discharge tests and cycle voltammetry (CV). The results demonstrate that LiFePO4/C have single olivine type structure with small particle sizes. The electrochemical test results show that the residual carbon produced by the pyrolysis of PS microspheres with functionalized aromatic groups exhibites a better discharge capacity in the LiFePO4/C composite. The LiFePO4/C cathode material with 7 wt% PS delivers an initial discharge capacity of 141mAh/g at 0.1C and between 2.5-4.1V, and displays excellent capacity retention. The composite material exhibited a higher peak intensity and a smaller voltage difference between the oxidation and reduction peak, indicating a good electrochemical reaction reversibility.