中国物理B ›› 2013, Vol. 22 ›› Issue (8): 88801-088801.doi: 10.1088/1674-1056/22/8/088801

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    

Analysis on the capacity degradation mechanism of a series lithium-ion power battery pack based on inconsistency of capacity

王震坡a, 刘鹏a b, 王丽芳b   

  1. a National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China;
    b Key Laboratory of Power Electronics and Electric Drive, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2013-01-28 修回日期:2013-04-17 出版日期:2013-06-27 发布日期:2013-06-27
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 61004092 and 51007088), the National High Technology Research and Development Program of China (Grant Nos. 2011AA11A251 and 2011AA11A262), the International Science & Technology Cooperation Program of China (Grant Nos. 2010DFA72760 and 2011DFA70570), and the Research Foundation of National Engineering Laboratory for Electric Vehicles, China (Grant No. 2012-NELEV-03).

Analysis on the capacity degradation mechanism of a series lithium-ion power battery pack based on inconsistency of capacity

Wang Zhen-Po (王震坡)a, Liu Peng (刘鹏)a b, Wang Li-Fang (王丽芳)b   

  1. a National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China;
    b Key Laboratory of Power Electronics and Electric Drive, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2013-01-28 Revised:2013-04-17 Online:2013-06-27 Published:2013-06-27
  • Contact: Wang Zhen-Po, Liu Peng E-mail:wangzhenpo@bit.edu.cn; roc726@163.com
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 61004092 and 51007088), the National High Technology Research and Development Program of China (Grant Nos. 2011AA11A251 and 2011AA11A262), the International Science & Technology Cooperation Program of China (Grant Nos. 2010DFA72760 and 2011DFA70570), and the Research Foundation of National Engineering Laboratory for Electric Vehicles, China (Grant No. 2012-NELEV-03).

摘要: The lithium-ion battery has been widely used as an energy source. Charge rate, discharge rate, and operating temperature are very important factors for the capacity degradations of power batteries and battery packs. Firstly, in this paper we make use of an accelerated life test and a statistical analysis method to establish the capacity accelerated degradation model under three constant stress parameters according to the degradation data, which are charge rate, discharge rate, and operating temperature, and then we propose a capacity degradation model according to the current residual capacity of a Li-ion cell under dynamic stress parameters. Secondly, we analyze the charge and discharge process of a series power battery pack and interpret the correlation between the capacity degradations of the battery pack and its charge/discharge rate. According to this cycling condition, we establish a capacity degradation model of a series power battery pack under inconsistent capacity of cells, and analyze the degradation mechanism with capacity variance and operating temperature difference. The comparative analysis of test results shows that the inconsistent operating temperatures of cells in the series power battery pack are the main cause of its degradation; when the difference between inconsistent temperatures is narrowed by 5 ℃, the cycle life can be improved by more than 50%. Therefore, it effectively improves the cycle life of the series battery pack to reasonably assemble the batteries according to their capacities and to narrow the differences in operating temperature among cells.

关键词: lithium-ion battery pack, series, capacity degradation, dynamic stress

Abstract: The lithium-ion battery has been widely used as an energy source. Charge rate, discharge rate, and operating temperature are very important factors for the capacity degradations of power batteries and battery packs. Firstly, in this paper we make use of an accelerated life test and a statistical analysis method to establish the capacity accelerated degradation model under three constant stress parameters according to the degradation data, which are charge rate, discharge rate, and operating temperature, and then we propose a capacity degradation model according to the current residual capacity of a Li-ion cell under dynamic stress parameters. Secondly, we analyze the charge and discharge process of a series power battery pack and interpret the correlation between the capacity degradations of the battery pack and its charge/discharge rate. According to this cycling condition, we establish a capacity degradation model of a series power battery pack under inconsistent capacity of cells, and analyze the degradation mechanism with capacity variance and operating temperature difference. The comparative analysis of test results shows that the inconsistent operating temperatures of cells in the series power battery pack are the main cause of its degradation; when the difference between inconsistent temperatures is narrowed by 5 ℃, the cycle life can be improved by more than 50%. Therefore, it effectively improves the cycle life of the series battery pack to reasonably assemble the batteries according to their capacities and to narrow the differences in operating temperature among cells.

Key words: lithium-ion battery pack, series, capacity degradation, dynamic stress

中图分类号:  (Energy content issues; life cycle analysis)

  • 88.05.Hj
88.85.Hj (Electric vehicles (EVs)) 82.47.Aa (Lithium-ion batteries) 88.80.ff (Batteries)