Axially and radially inhomogeneous swelling in commercial 18650 Li-ion battery cells

Pavel Blazek, Peter Westenberger, Simon Erker, Adam Brinek, Tomas Zikmund*, Daniel Rettenwander, Nils Peter Wagner, Jozef Keckes, Jozef Kaiser, Tomas Kazda, Petr Vyroubal, Martin Macak, Juraj Todt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Aging of lithium-ion batteries is especially important for applications such as battery electric vehicles, where they constitute a major part of the total cost and practically determine product lifetime. One of the main problems during cycle aging is the swelling of the electrode stack, as this results in increased mechanical stresses inside batteries and can further accelerate aging. Earlier studies have used X-ray tomography to address this issue and were focused on the role of large aberrations in electrode geometry in rapid capacity fade. In this study, however, we focus on batteries not exhibiting such a rapid deterioration, where only small changes to electrode geometry can be expected. Helical trajectory micro-computed X-ray tomography and virtual unrolling were used to reveal axially and radially inhomogeneous swelling of the jelly-roll electrode windings inside commercial 18650 batteries. The results supported by mathematical-physical simulations demonstrate the efficacy of the employed methods in the analysis of minute volumetric changes and show that regions inside the batteries that are comparatively unconstrained mechanically experience accelerated swelling. In particular, the top and bottom of the jelly-roll showed an elevated thickness increase, especially within the innermost windings.

Original languageEnglish
Article number104563
JournalJournal of Energy Storage
Issue numberPart B
Publication statusPublished - 15 Aug 2022


  • Aging
  • Lithium-ion battery
  • Swelling
  • Virtual unrolling
  • X-ray computed tomography

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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