(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%。
关键字: 低温电解液；磷酸铁锂；相容性；电化学性能
（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 LiFePO4 cathode 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 LiFePO4 batteries. 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
