物理化学学报 >> 2007, Vol. 23 >> Issue (07): 1117-1122.doi: 10.3866/PKU.WHXB20070730

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焙烧温度对合成LiFePO4的产物组成和电化学性能的影响

刘素琴; 龚本利; 黄可龙; 张戈; 李世彩   

  1. 中南大学化学化工学院, 长沙 410083
  • 收稿日期:2006-12-08 修回日期:2007-02-09 发布日期:2007-07-03
  • 通讯作者: 刘素琴 E-mail:Sqliu2003@126.com

Effect of Calcination Temperature on the Compositions and Electrochemical Performance of Products in the Synthesis of LiFePO4

LIU Su-Qin; GONG Ben-Li; HUANG Ke-Long; ZHANG Ge; LI Shi-Cai   

  1. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
  • Received:2006-12-08 Revised:2007-02-09 Published:2007-07-03
  • Contact: LIU Su-Qin E-mail:Sqliu2003@126.com

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摘要： 以FePO4为前驱体, 采用碳热还原法合成了LiFePO4/C复合正极材料; 通过TG-DTA、FTIR、XRD 等技术研究了反应历程, 分析了不同焙烧温度下产物的组成及杂相存在的原因, 并测试了其电化学性能. 研究表明, 300 ℃下LiFePO4已作为主要的相存在, 显示了较低的成相温度; 300、400、500 ℃下样品中存在一定量的杂相Li3PO4和Fe2O3, 600 ℃得到纯相的LiFePO4, 而在700 ℃下出现了焦磷酸盐Li4P2O7, 这些杂相的存在影响了其电化学性能, 600 ℃样品具有最佳的电化学性能, 其在0.1C下首次放电容量达146 mAh·g-1, 循环15 次后容量还保持为141 mAh·g-1.

关键词: 焙烧温度, LiFePO4, 组成, 电化学性能

Abstract:

LiFePO4/C composite cathode materials were synthesized by carbothermal reduction (CTR) method using FePO4 as precursor. The precursors and the products were characterized by TG-DTA, FTIR, XRD, and the reaction mechanism was investigated. The compositions and electrochemical performance of the products at different calcination temperatures were studied. The results showed that LiFePO4 in the sample prepared at 300 ℃ was primary phase, so the crystallization temperature in this route was lower than that of other methods. At 300, 400, 500 ℃, Li3PO4 and Fe2O3 as impurity phases existed in the samples and the higher temperature led to less impurity phases. The sample calcined at 600 ℃ had no impurity, but Li4P2O7 appeared at 700 ℃. The sample prepared at 600 ℃ for 24 h had the best electrochemical performance, which could deliver a discharge capacity of 146 mAh·g-1 at 0.1C and retain a discharge capacity of 141 mAh·g-1 after 15 cycles.

Key words: Calcination temperature, LiFePO4, Compositions, Electrochemical performance