(浙江大学 材料科学与工程学系，杭州310027)
摘 要: 以FePO4为铁源、Li2CO3为锂源、聚丙烯为还原剂和碳源，采用一步固相法合成原位碳包覆磷酸亚铁锂(LiFePO4/C)复合材料，研究合成温度对材料LiFePO4/C复合材料电化学性能的影响。采用X射线衍射、扫描电镜和拉曼光谱技术对合成产物的晶体结构、表面形貌和碳结构进行表征，通过电化学阻抗谱(EIS)和充放电测试对材料的电化学性能进行测试和分析。结果表明：在600~750 ℃温度范围内都可合成纯LiFePO4/C复合材料，随着合成温度的升高，材料颗粒尺寸和石墨化程度都将增大；600 ℃保温8 h合成的材料颗粒尺寸为100~500 nm，其1 C放电比容量达到144.2 mA∙h/g，5 C放电比容量达到119 mA∙h/g。
关键字: LiFePO4/C；锂离子电池；正极材料
（Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China）
Abstract:LiFePO4/C composites were synthesized by one-step solid-state reaction using FePO4 and Li2CO3 as raw materials and polypropylene as reductive agent and carbon source. The effect of synthesis temperature on the electrochemical performances of LiFePO4/C composites was studied. The microstructure, morphology of the products and the structure of carbon were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Raman microprobe spectra. The electrochemical impedance spectroscopy (EIS) and charge-discharge test were used to study their electrochemical performances. The results show that LiFePO4/C composites can be synthesized in the temperature range from 600 to 750 ℃. The size of the particle and the degree of graphitization increase with increasing synthesis temperature. The size of LiFePO4/C composites synthesized at 600 ℃ for 8 h is about 100−500 nm, and it has discharge capacities of 144.2 and 119 mA∙h/g at 1 C and 5 C rates, respectively.
Key words: LiFePO4/C; lithium ion batteries; cathode materials
