(浙江大学 材料系， 杭州 310027)
摘 要: 用廉价的三价铁离子化合物为铁源， 以聚丙烯为还原剂和碳源， 在一步固相法合成Nb掺杂LiFePO4的同时实现颗粒表面碳导电膜的原位包覆。 结果表明： 一步固相合成的Nb掺杂LiFePO4/C具有完整的橄榄石型LiFePO4晶体结构和近似球状的颗粒形貌， 颗粒尺寸为100~500 nm； 聚丙烯分解后在颗粒表面和颗粒之间形成连通的网络状碳膜。 电化学测试结果表明， 当Nb的掺入量为1.0％（摩尔分数）时具有最好的倍率放电性能和循环性能； 在2 C充放电时具有130 mA·h/g的放电容量， 循环100次容量无衰减， 在4 C充放电时仍具有105 mA·h/g的放电容量。
关键字: 磷酸铁锂; 锂离子电池；正极材料; 固相合成; Nb掺杂
Nb doped LiFePO4/C prepared by
one-step solid-state synthesis
（Department of Materials, Zhejiang University, Hangzhou 310027, China）
Abstract: Nb-doped lithium iron phosphates were synthesized and in-situ carbon coated by one-step solid-state reaction using ferrous compound as the iron source and polypropylene as the reductive agent and carbon source. The results show that the one-step solid-state synthesized Nb doped LiFePO4/C powders are near-spherical particles of 100-500 nm with the olivine type LiFePO4 structure, and wrapped with carbon nets decomposed from polypropylene. Electrochemical analyses show that LiFePO4/C with 1.0% Nb(in mole fraction) doping has the best rate performances and cycling stability with a discharge capacity of 130 mA·h/g retained up to 100 cycles at 2 C rate and 105 mA·h/g at 4 C rate.
Key words: lithium iron phosphate; lithium ion batteries; cathode materials; solid-state synthesis; niobium doping
