合成温度对LiFePO_4/C复合材料电化学性能的影响  

Effect of synthesis temperature on electrochemical performances of LiFePO_4/C composites

作　　者：郑威[1] 余红明[1] 曹高劭[1] 赵新兵[1] 

机构地区：[1]浙江大学材料科学与工程学系,杭州310027

出　　处：《中国有色金属学报》2010年第3期572-577,共6页The Chinese Journal of Nonferrous Metals

基　　金：浙江省科技计划资助项目(2007C21100)

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8h合成的材料颗粒尺寸为100～500nm,其1C放电比容量达到144.2mA·h/g,5C放电比容量达到119mA·h/g。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.

关 键 词：LIFEPO4/C 锂离子电池 正极材料 

分 类 号：TM912.9[电气工程—电力电子与电力传动]