Review - "Knees" in Lithium-Ion Battery Aging Trajectories

Peter M. Attia, Alexander Bills, Ferran Brosa Planella, Philipp Dechent, Gonçalo Dos Reis, Matthieu Dubarry, Paul Gasper, Richard Gilchrist, Samuel Greenbank, David Howey, Ouyang Liu, Edwin Khoo, Yuliya Preger, Abhishek Soni, Shashank Sripad, Anna G. Stefanopoulou, Valentin Sulzer

Research output: Contribution to journalArticlepeer-review

140 Scopus Citations


Lithium-ion batteries can last many years but sometimes exhibit rapid, nonlinear degradation that severely limits battery lifetime. In this work, we review prior work on "knees"in lithium-ion battery aging trajectories. We first review definitions for knees and three classes of "internal state trajectories"(termed snowball, hidden, and threshold trajectories) that can cause a knee. We then discuss six knee "pathways", including lithium plating, electrode saturation, resistance growth, electrolyte and additive depletion, percolation-limited connectivity, and mechanical deformation - some of which have internal state trajectories with signals that are electrochemically undetectable. We also identify key design and usage sensitivities for knees. Finally, we discuss challenges and opportunities for knee modeling and prediction. Our findings illustrate the complexity and subtlety of lithium-ion battery degradation and can aid both academic and industrial efforts to improve battery lifetime.

Original languageAmerican English
Article number060517
Number of pages29
JournalJournal of the Electrochemical Society
Issue number6
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.

NREL Publication Number

  • NREL/JA-5700-82801


  • Battery degradation
  • Battery lifetime
  • Battery lifetime prediction
  • Battery modeling
  • Knee point
  • Lithium-ion batteries


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