物理化学学报 >> 2009, Vol. 25 >> Issue (09): 1916-1920.doi: 10.3866/PKU.WHXB20090929

研究论文 上一篇    下一篇

锂离子电池复合正极材料xLiFePO4·yLi3V2(PO4)3的复合机制

郑俊超, 李新海, 王志兴, 李金辉, 伍凌, 李灵均, 郭华军   

  1. 中南大学冶金科学与工程学院, 长沙 410083|江西理工大学材料与化学工程学院, 江西 赣州 341000
  • 收稿日期:2009-04-17 修回日期:2009-06-12 发布日期:2009-09-03
  • 通讯作者: 李新海 E-mail:tonyson_011@163.com

A Coalescence Mechanism for the Composite Cathode Material xLiFePO4·yLi3V2(PO4)3

ZHENG Jun-Chao, LI Xin-Hai, WANG Zhi-Xing, LI Jin-Hui, WU Ling, LI Ling-Jun, GUO Hua-Jun   

  1. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, P. R. China|School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province, P. R. China
  • Received:2009-04-17 Revised:2009-06-12 Published:2009-09-03
  • Contact: LI Xin-Hai E-mail:tonyson_011@163.com

摘要:

以FePO4·xH2O、V2O5、NH4H2PO4和Li2CO3为原料, 以乙二酸为还原剂, 通过湿化学还原-低温热处理方法制备出锂离子复合正极材料xLiFePO4·yLi3V2(PO4)3. X射线衍射(XRD)结果表明, 合成的材料中橄榄石结构的LiFePO4和单斜晶系的Li3V2(PO4)3两相共存; 从复合材料中LiFePO4、Li3V2(PO4)3相对于相同条件下制备的纯相LiFePO4和Li3V2(PO4)3的晶格常数变化以及结合高分辨透射电子显微镜(HRTEM)、能量散射X射线(EDAX)的结果可以看出, 在复合材料xLiFePO4·yLi3V2(PO4)3中存在部分V和Fe, 分别掺杂在LiFePO4和Li3V2(PO4)3中, 并形成固溶体; X射线光电子能谱(XPS)结果表明, Fe/V在复合材料中的价态与各自在LiFePO4和Li3V2(PO4)3中的价态保持一致, 分别为+2 和+3价. 充放电测试表明, 制备出的复合正极材料电化学性能明显优于单一的LiFePO4和Li3V2(PO4)3; 循环伏安测试表明, 复合正极材料具有优良的脱/嵌锂性能.

关键词: 锂离子电池, 复合正极材料, 掺杂, xLiFePO4·yLi3V2(PO4)3

Abstract:

Composite cathode material xLiFePO4·yLi3V2(PO4)3 was obtained from wet chemical reduction and lithiation method by using FePO4·xH2O, V2O5, NH4H2PO4, Li2CO3 as raw materials and oxalic acid as reductant. X-ray diffraction (XRD) results showed that the composite material contained olivine LiFePO4 and monoclinic Li3V2(PO4)3 phases. High resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrometry (EDAX) results indicated that some LiFePO4 and Li3V2(PO4)3 in the composite material were doped by V and Fe, respectively, and formed a solid solution. The valences of Fe and V doping in Li3V2(PO4)3 and LiFePO4 are +2 and +3, respectively. Charge and discharge tests showed that the synthesized composite material exhibited better electrochemical performance than individual LiFePO4 and Li3V2(PO4)3. Cyclic voltammetry indicated the composite material showing good lithium ions extraction/insertion property.

Key words: Lithium ion battery, Composite cathode material, Doping, xLiFePO4·yLi3V2(PO4)3

MSC2000: 

  • O646