(浙江大學(xué) 材料系， 杭州 310027)
摘 要: 用廉價的三價鐵離子化合物為鐵源， 以聚丙烯為還原劑和碳源， 在一步固相法合成Nb摻雜LiFePO4的同時實現(xiàn)顆粒表面碳導(dǎo)電膜的原位包覆。 結(jié)果表明： 一步固相合成的Nb摻雜LiFePO4/C具有完整的橄欖石型LiFePO4晶體結(jié)構(gòu)和近似球狀的顆粒形貌， 顆粒尺寸為100~500 nm； 聚丙烯分解后在顆粒表面和顆粒之間形成連通的網(wǎng)絡(luò)狀碳膜。 電化學(xué)測試結(jié)果表明， 當Nb的摻入量為1.0％（摩爾分數(shù)）時具有最好的倍率放電性能和循環(huán)性能； 在2 C充放電時具有130 mA·h/g的放電容量， 循環(huán)100次容量無衰減， 在4 C充放電時仍具有105 mA·h/g的放電容量。
關(guān)鍵字: 磷酸鐵鋰; 鋰離子電池；正極材料; 固相合成; Nb摻雜
Nb doped LiFePO4/C prepared by
one-step solid-state synthesis
MA Sheng-lin, XIE Jian, ZHU Tie-jun
（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
