基于交流阻抗法的退役磷酸铁锂动力电池分选成组技术研究

Sorting and grouping technology for retired lithium iron phosphate batteries of electrical vehicles based on electrochemical impedance spectroscopy

使用电化学工作站,通过交流阻抗法对70只退役磷酸铁锂动力电池进行了分析,得到了优化后的等效电路;系统研究了等效电路中各元件的参数与电池荷电状态的相关性。结果显示,使用交流阻抗谱中的欧姆内阻作为分组指标,分选后的电池组容量衰减率均低于常规内阻-容量法选出的电池组。该研究可为今后高通量、规模化筛选重组退役磷酸铁锂动力电池提供新的方法和理论依据。

In this paper, seventy retired lithium iron phosphate power batteries were analyzed by the electrochemical impedance spectroscopy(EIS)using an electrochemical workstation, and the optimized equivalent circuits were obtained. The correlation between the parameters of each element in the equivalent circuits and the states of charge of the batteries were systematically studied. The results showed that the capacity attenuation rate of the battery module sorted and grouped by EIS ohmic internal resistance method was lower than that by the conventional internal impedance-capacity method. This work provides a new method and theory basis for high-throughput, large-scale sorting and recombination of retired lithium iron phosphate batteries of electrical vehicles in the future.