还原条件对碳热还原合成LiFePO_4/C大倍率性能的影响

Effects of the reduction conditions on the rate performance of LiFePO_4/C prepared by carbothermal reduction

以FePO4.2H2O为铁源,LiOH.H2O为锂源,蔗糖为碳源和还原剂,用碳热还原法制备得到LiFePO4/C复合正极材料。用X射线衍射法(XRD)、恒流充放电技术及循环伏安(CV)和交流阻抗(EIS)考察还原温度和还原时间对碳热还原合成材料结构和电化学性能的影响。结果表明,还原温度650℃、还原时间8.5 h条件下所得材料为单相橄榄石结构,10C放电比容量达121.8 mAh/g,循环100次后容量保持率为100%,具有良好的倍率性能和循环性能。研究结果可促进该材料在锂离子动力电池中的应用。

The LiFePO4/C composites were synthesized by the carbothermal reduction using FePO4 · 2H20 and LiOH · H20 as raw materials and sucrose as reductive agent and carbon source. The effects of synthetic temperature and time on the structure and electrochemical performances of LiFePO4/C composites were studied. The LiFePOn/C was analyzed by X-ray diffraction （XRD） , chargedischarge test, electrochemical impedance spectroscopy （EIS） and cyclic voltammetry （CV）. The results showed that the LiFePOJC sample prepared with a sintering temperature of 650℃ and a sintering time of 8.5 h, formed the olivine structure with the space group Pnmb. Electrochemical tests indicated that this LiFePOJC sample delivered a discharge special capacity of 121.8mAh/g with a capacity retention rate of 100% after 100 cycles at 10C, exhibiting good rate performance and cycle performance. These advantages were useful for the application of power batteries.