Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (11): 3479-3487.doi: 10.19799/j.cnki.2095-4239.2023.0510

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

Estimation of the state of health of lithium-ion batteries based on feature extraction of the relaxation process

Chen GENG1(), Jinhao MENG1(), Qiao PENG1, Tianqi LIU1, Xueyang ZENG2, Gang CHEN2   

  1. 1.College of Electrical Engineering, Sichuan University, Chengdu 610065, Sichuan, China
    2.State Grid Sichuan Electric Power Company Electric Power Research Institute, Chengdu 610072, Sichuan, China
  • Received:2023-07-27 Revised:2023-08-08 Online:2023-11-05 Published:2023-11-16
  • Contact: Jinhao MENG E-mail:gchyc1206@163.com;jinhao@scu.edu.cn

Abstract:

Lithium-ion battery is an important part of the fixed electrochemical energy storage, and the estimation of its state of health (SOH) is of great significance for its safe and stable operation. At present, health-feature extraction is focused on the charging stage of a battery, and few methods have been developed to extract health features at the relaxation stage. This study proposes a method to extract health features from the relaxation stage and use Gaussian process regression (GPR) to estimate the SOH. First, based on the accelerated cycle aging test data of Li-NMC batteries, the variation of the time constant at the relaxation stage is analyzed, and a power function, which reflects the terminal voltage in the relaxation stage well, is used for modeling. Second, the key features that can characterize the relaxation stage are extracted, and the SOH estimation model is established based on GPR. Finally, the accuracy was verified using batteries with different aging current multiplicities. The results are compared when the model is generated using 15- and 60-minute relaxation-stage curves. The accuracy of the Gaussian-process regression method is also compared with support vector machine and tree regression method, and the accuracy of SOH estimation was verified under multiple states of charge. The proposed SOH estimation model was validated to achieve an optimal root mean square error (RMSE) of 0.6%; the RMSE is still less than 1% when using 15-minute data for SOH estimation.

Key words: lithium-ion battery, SOH estimation, relaxation stage, gaussian process regression, feature extraction

CLC Number: