Energy Storage Science and Technology ›› 2019, Vol. 8 ›› Issue (6): 1089-1095.doi: 10.12028/j.issn.2095-4239.2019.0098

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Multi-stage capacity loss of lithium-ion batteries originating from the multi-slope nature of open circuit voltage curves

GE Hao1, LI Zhe1,2, ZHANG Jianbo1,2   

  1. 1 State Key Laboratory of Automotive Safety and Energy, Department of Automotive Engineering, Tsinghua University, Beijing 100084, China;
    2 Beijing Co-innovation Center for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China
  • Received:2019-05-21 Revised:2019-06-25 Online:2019-11-01 Published:2019-11-01

Abstract: An inflexion point during battery aging, turning the capacity retention curve from a gradually decreasing region into an abrupt drop, has been reported for a diversity of lithium-ion battery materials. Understandings such a multi-stage aging phenomenon are vital to lifespan design and cascade use of batteries, while they remain hitherto elusive. We unravel that the multi-stage aging behavior can result from the multi-slope nature of open-circuit-voltage (OCV) curve of batteries. Increasing kinetic polarization during aging renders the discharging process terminated in the OCV region with different slopes, leading to distinct aging profiles. In this work, we firstly demonstrate this basic idea using a two-stage example. Then, a general theory of inflexion point in battery aging considering both the positive and negative electrode is extended which is rather facile to incorporate major aging mechanisms and battery chemistries. This work provides new insights in understanding the multi-stage aging behavior, which can further contribute to the lifespan design and reuse of lithium-ion batteries.

Key words: lithium-ion battery aging, shape of open circuit voltage curve, multi-stage, abrupt capacity loss, reuse

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