焙烧温度对合成LiFePO_4的产物组成和电化学性能的影响  

Effect of Calcination Temperature on the Compositions and Electrochemical Performance of Products in the Synthesis of LiFePO_4

作　　者：刘素琴[1] 龚本利[1] 黄可龙[1] 张戈[1] 李世彩[1] 

机构地区：[1]中南大学化学化工学院,长沙410083

出　　处：《物理化学学报》2007年第7期1117-1122,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20376086);教育部博士点基金(20030533001)资助项目

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146mAh·g-1,循环15次后容量还保持为141mAh·g-1.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.

关 键 词：焙烧温度 LIFEPO4 组成 电化学性能 

分 类 号：O614.111[理学—无机化学]