Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (11): 3528-3537.doi: 10.19799/j.cnki.2095-4239.2023.0447

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

Application of equivalent circuit model of lithium-ion batteries to high current rate condition

Yunteng DAI1(), Qiao PENG1(), Tianqi LIU1, Xueyang ZENG2, Gang CHEN2, Yan LI2, Jinhao MENG1   

  1. 1.College of Electrical Engineering, Sichuan University, Chengdu 610065, Sichuan, China
    2.State Grid Sichuan Electric Power Research Institute, Chengdu 610041, Sichuan, China
  • Received:2023-06-27 Revised:2023-07-03 Online:2023-11-05 Published:2023-11-16
  • Contact: Qiao PENG E-mail:daiyunteng@stu.scu.edu.cn;qpeng@scu.edu.cn

Abstract:

The equivalent circuit model (ECM) is one of the primary types of battery models that play a crucial role in battery characteristic analysis and state estimation. However, the widely used resistor-capacitor (RC) structured ECM currently in use fails to adapt to complex and dynamic scenarios. For instance, traditional ECMs fail to accurately reflect the special phenomenon of battery polarization voltage under high current rates, unable to accurately characterize the impedance characteristics of batteries at high current rate conditions. To address this, the present study conducts battery peak current experiments at different states of charge and analyzes the polarization voltage and impedance characteristics of the battery under peak current conditions using experimental data. Then, a negative resistance-capacitance segment is introduced to fit the experimental results, and the conventional ECM is improved to better represent the polarization phenomena under high current rate conditions. Additionally, a parameter separation method based on the inflection points of impedance curves is proposed by comparing the characteristics of the conventional RC segment with the negative RC segment. The proposed method has low computational complexity and a convenient model solution. Finally, the model with separated parameters is validated. The results show that the proposed ECM and parameter identification method can effectively realize the polarization voltage variation of the battery under high current rate conditions and can accurately represent the battery voltage characteristics. The experimental results demonstrate that the proposed model maintains an error of <0.05 V. Moreover, the proposed ECM greatly enhances the accuracy compared with the conventional RC model, and it does not rely on complex electrochemical models, maintaining a simple model structure.

Key words: lithium-ion batteries, equivalent circuit models, battery impedance characteristics, polarization voltages, peak current experiments

CLC Number: