电解液组成对LiFePO 4电池低温性能的影响

第23卷第11期中国有色金属学报2013年11月V ol.23 No.11The Chinese Journal of Nonferrous Metals Nov. 2013文章编号：1004-0609(2013)11-3189-07

电解液组成对LiFePO4电池低温性能的影响

赖静远1，邹忠1，徐俊毅1，张治安1，赖延清1,2，李劼1,2，刘晋1

(1. 中南大学冶金与环境学院，长沙410083；

2. 中南大学先进电池材料教育部工程研究中心，长沙410083)

摘要：研究了低温(?20 ℃)下磷酸铁锂正极材料与电解液的相容性。采用不同溶剂组成的电解液与磷酸铁锂正极组装成LiFePO4/Li半电池，进行电化学测试。结果表明：低温下电池界面阻抗是影响磷酸铁锂电池性能的关键因素；随着界面阻抗的增大，LiFePO4/Li半电池的放电容量显著下降，同时极化加重，放电平台降低，并且其界面阻抗的变化直接与电解液中线性酯和环状酯溶剂的比例相关。在?20 ℃下，环状酯类溶剂含量(体积分数)为33%的电解液界面阻抗最小，其组装的LiFePO4/Li半电池0.1C倍率下放电容量为113.9 mA·h/g，是常温放电容量的75%。

关键词：低温电解液；磷酸铁锂；相容性；电化学性能

中图分类号：TQ152 文献标志码：A

Effect of electrolyte component on low-temperature

performance of LiFePO4 batteries

LAI Jing-yuan1, ZOU Zhong1, XU Jun-yi1, ZHANG Zhi-an1, LAI Yan-qing1,2, LI Jie1,2, LIU Jin1

(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;

2. Research Center of Advanced Battery Materials Engineering, Ministry of Education,

Central South University, Changsha 410083, China)

Abstract:The compatibility of LiFePO4cathode with electrolyte at low temperature (

?20 ℃) was studied.

Electrochemical analysis was employed to investigate a series of electrolytes with different compositions for the LiFePO4/Li half cells. The results show that the interface impendence at low temperature is the key factor affecting the performance of LiFePO4batteries. The discharging capacity of the LiFePO4/Li cells significantly decreases, and the polarization and resistance increase due to an increase in the interface impedance between the electrode and electrolyte.

In addition, the interface impedance change is directly related to the ratio of the linear and cyclic carbonate solvents. At ?20 ℃, the electrolyte with 33% (volume fraction) cyclic carbonate has the lowest interface impedance. The discharging capacity of the corresponding LiFePO4/Li half cells is 113.9 mA·h/g and about 75% as that of the room temperature one.

Key words: low temperature electrolyte; LiFePO4 cathode; compatibility; electrochemical performance

20世纪90年代中期，锂离子电池在航天航空和军事领域的应用对其低温性能提出了更高的要求。为了提高低温下锂离子电池的功率和比能量密度，人们开始着手低温电解液的研究[1?3]，针对的电池正极材料以LiCoO2、LiNiCoO2和LiMn2O4为主。1997年GOODENOUGH的课题组[4]报道了橄榄石结构的LiFePO4材料的嵌脱锂特性后，该材料很快成为了学术界和产业界的宠儿。与LiCoO2等材料相比，LiFePO4具有安全性高、成本低和循环寿命长等优点，而这正是动力电池领域重点关注的几个性能。然而，LiFePO4

基金项目：国家自然科学基金资助项目(51274239)

收稿日期：2013-04-09；修订日期：2013-09-01

通信作者：刘晋，教授，博士；电话：0731-********；E-mail：liujincsu@https://www.wendangku.net/doc/af12296640.html,