Battery capacity knee-onset identification and early prediction using degradation curvature
Artikel i vetenskaplig tidskrift, 2024

Abrupt capacity fade can have a significant impact on performance and safety in battery applications. To address concerns arising from possible knee occurrence, this work aims for a better understanding of their cause by introducing a new definition of capacity knees and their onset. A curvature-based identification of a knee and its onset is proposed, which relies on the discovery of a distinctly fluctuating behavior in the transition between an initial and a final stable acceleration of the degradation. The method is validated on experimental degradation data of two different battery chemistries, synthetic degradation data, and is also benchmarked to the state-of-the-art knee identification method in the literature. The results demonstrate that our proposed method could successfully identify capacity knees when the state-of-the-art knee identification method failed. Furthermore, a significantly strong correlation is found between knee and end of life (EoL) and almost equally strong between knee onset and EoL. As the method does not require the full capacity fade curve, this opens up online knee-onset identification as well as knee and EoL prediction.

Curvature approximation

Degradation mechanisms

Knee identification

Battery diagnosis

Knee-onset early prediction


Huang Zhang

Volvo Group

Chalmers, Elektroteknik, System- och reglerteknik

Faisal Altaf

Volvo Group

Torsten Wik

Chalmers, Elektroteknik, System- och reglerteknik

Journal of Power Sources

0378-7753 (ISSN)

Vol. 608 234619

Klassificering och optimal hantering av 2nd life xEV-batterier

Energimyndigheten (45540-1), 2018-10-15 -- 2023-06-30.


Hållbar utveckling


Biologiska vetenskaper

Elektroteknik och elektronik



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