Energy Storage Science and Technology ›› 2025, Vol. 14 ›› Issue (2): 770-778.doi: 10.19799/j.cnki.2095-4239.2024.0749

• Energy Storage Test: Methods and Evaluation • Previous Articles     Next Articles

SOH estimation based on distribution of relaxation times for the retired power lithium-ion battery

Ziheng ZHANG1(), Mengmeng GENG2, Maosong FAN2, Yuhong JIN1(), Jingbing LIU1, Kai YANG2, Hao WANG1   

  1. 1.College of Materials Science and Engineering Beijing University Of Technology, Beijing 100124, China
    2.China Electric Power Research Institute, Beijing 100192, China
  • Received:2024-08-12 Revised:2024-09-01 Online:2025-02-28 Published:2025-03-18
  • Contact: Yuhong JIN E-mail:zihengzhang@emails.bjut.edu.cn;jinyh@bjut.edu.cn

Abstract:

Retired batteries should undergo rigorous testing and evaluation to ascertain their performance before they are deployed in echelons utilization to ensure that appropriate application scenarios are selected based on the performance of the batteries. An accurate assessment of the State of Health (SOH) is fundamental to determine whether a power battery possesses the value of echelons utilization. In view of the low accuracy of SOH evaluation of retired power batteries, the relaxation time distribution method was used to analyze the electrochemical impedance spectroscopy in this study. This was done to obtain the characteristic frequency that can accurately reflect the health state of the battery. The impedance data corresponding to the characteristic frequency was used as the characteristic input parameters, and the extreme learning machine model optimized using the sparrow algorithm served as input to realize the SOH evaluation of decommissioned power batteries. To verify the effectiveness of the evaluation method, seven retired prismatic lithium-iron-phosphate batteries were subjected to cyclic aging experiments, and electrochemical impedance spectroscopy tests were performed on the batteries after each cycle. Actual electrochemical impedance spectroscopy of the decommissioned power batteries was used for analysis and modeling to evaluate the SOH, and the results were compared with actual SOH data obtained using traditional SOH evaluation methods. Our findings demonstrate that the Mean Square Error (MSE) and Mean Absolute Percentage Error (MAPE) associated with the relaxation time distribution method are lower than those of other methods. Compared with the unoptimized extreme learning machine model, the values of the MSE and MAPE reduced by 47.1% and 60.5%, respectively, indicating that the SOH evaluation method employed in this study is relatively highly accurate and less prone to error, indicating its applicability in practical echelons utilization.

Key words: retired lithium-ion power battery, state of health, electrochemical impedance spectroscopy, distribution of relaxation times, extreme learning machine

CLC Number: