( 1. 廣西大學(xué) 化學(xué)化工學(xué)院, 南寧 530004；
2. 中國地質(zhì)科學(xué)院 鹽湖中心， 北京 100037)
摘 要: 為提高LiFePO4的充放電性能， 用Ni2+對LiFePO4進行摻雜。 采用電化學(xué)方法測量了Li1-xNixFePO4的充放電性能， 用X射線衍射和里特沃爾特方法表征了摻雜LiFePO4的晶體結(jié)構(gòu)。 固相反應(yīng)可制備單相
Li1-xNixFePO4 (x=0.00、 0.01、 0.02、 0.03、 0.05和0.07， 摩爾分?jǐn)?shù))。 研究表明： 少量鎳離子摻雜能有效地提高LiFePO4的比容量和循環(huán)性能， 其中Li0.97Ni0.03FePO4具有更好的電化學(xué)性能， 放電比容量高出LiFePO4約30 mA·h/g， 其主要原因是鎳離子摻雜不僅改變了晶體中原子間距離和位置， 引起晶胞收縮； 而且增加了LiFePO4中Fe3+/Fe2+共存態(tài)的濃度， 提高了材料的導(dǎo)電能力。
關(guān)鍵字: LiFePO4； 鋰離子電池； 正極材料； 鎳摻雜
SU Hai-feng1, XUE Min-hua1
（ 1. School of Chemistry and Chemical Engineering, Guangxi University,
Nanning 530004, China;
2. Research and Development Center of Saline Lake and Epithermal Deposits, Chinese Academy of Geological Science, Beijing 100037, China）
Abstract: To improve the performance of LiFePO4, single phase Li1-xNixFePO4 was prepared by solid state reaction (x=0.00, 0.01, 0.02, 0.03, 0.05 and 0.07, mole fraction). Crystal structure and charge/discharge performance of doped LiFePO4 were investigated by X-ray diffractrometry with the Rietveld method and electrochemical measurement, respectively. The results show that Ni2+ doping with low concentration can increase the capacity and cycle performances of LiFePO4, and Li0.97Ni0.03FePO4 has better performance than the others, whose discharge capacity is 30 mA·h/g higher than LiFePO4. Because Ni2+ doping not only causes the change of atomic position and distance and the shrinkage of crystal cell, but also increases the concentration of coexisted Fe3+/Fe2+ in LiFePO4， which increases the electrical conductivity of LiFePO4.
Key words: LiFePO4; lithium-ion battery; cathode material; Ni2+ doping
