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Automotive Engineering ›› 2024, Vol. 46 ›› Issue (7): 1167-1176.doi: 10.19562/j.chinasae.qcgc.2024.07.004

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Diagnosis for Battery Module Inconsistencies Based on Electrochemical Impedance Spectroscopy

Hanxin Yao1,2,Xueyuan Wang1,2(),Yongjun Yuan1,2,3,Haifeng Dai1,2(),Xuezhe Wei1,2   

  1. 1.School of Automotive Studies,Tongji University,Shanghai  201804
    2.Clean Energy Automotive Engineering Center,Tongji University,Shanghai  201804
    3.Shanghai Fire Cloud New Energy Technology Co. ,Ltd. ,Shanghai  201806
  • Received:2023-10-22 Revised:2023-12-18 Online:2024-07-25 Published:2024-07-22
  • Contact: Xueyuan Wang,Haifeng Dai E-mail:7wangxueyuan@tongji.edu.cn;tongjidai@tongji.edu.cn

Abstract:

There may be inconsistencies in temperature, charge state, aging state (capacity and internal resistance) between individual cells in a battery module. Due to the existence of the "short board effect", the inconsistencies will affect the overall performance of the battery module, so timely and accurate inconsistencies diagnosis is very necessary. Considering that the above-mentioned inconsistencies will affect the electrode process characteristics, which will be reflected in the Electrochemical Impedance Spectroscopy (EIS) and Distribution of Relaxation Time (DRT), in this paper, after clarifying the effect of several kinds of inconsistencies on EIS and DRT by combining the equivalent circuits, an inconsistencies diagnosis method for battery modules based on EIS and DRT is innovatively proposed. The performance of unsupervised clustering algorithms such as K-means, AP (Affinity Propagation) and DBSCAN (Density Based Spatial Clustering of Applications with Noise) is comparatively analyzed by mixing the abnormal batteries into a group of batteries with good consistency. The results show that the DBSCAN diagnostic accuracy is 99.2%, which can realize the accurate diagnosis of the inconsistency difference of single cells within the battery module.

Key words: lithium-ion batteries, electrochemical impedance spectroscopy, distribution of relaxation time, inconsistency, unsupervised clustering