Influence of loading rate and out of plane direction dependence on deformation and electro-mechanical failure behavior of a lithium-ion pouch cell

Marco Raffler*, Wolfgang Sinz, Simon Erker, Bernhard Brunnsteiner, Christian Ellersdorfer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding the behavior of lithium-ion battery cells under complex load situations that can occur in vehicle crash scenarios is important to integrate the cells in the best possible way in an electrified vehicle. Since individual cell components partly show highly anisotropic material behavior, this work investigates whether a direction-dependent behavior is present on cell level when loaded in the out-of-plane direction, which has not been investigated so far. Cylindrical indentation tests in out-of-plane direction were performed on a 41 Ah NMC pouch cell under laboratory conditions. Thereby, impactor orientation, loading speed and electrolyte quantity were varied in order to study the respective influences both, separately as well as in interaction with each other. Component tensile tests with different directions and speeds were carried out. The results were compared with those of the cell tests for a better understanding of the observed electro-mechanical behavior. It could be shown that the investigated cell shows a significant out-of-plane direction dependence at low-speed loading (1 mm/s). This results in an approximately 23 % lower failure strain when the impactor is aligned along the long side of the cell compared to its alignment along shot side. Strain rate influences cell behavior, resulting in higher stiffness and lower failure strain at higher loading speeds (3000 mm/s). Furthermore, the out-of-plane direction dependence is reduced at higher loading speed, which is in direct contrast to the observations of the tensile tests. This is attributed to viscosity effects during high-speed loading, since the liquid electrolyte affects the mechanical cell behavior, as shown by the experiments with reduced electrolyte quantity. This study shows that the out-of-plane direction dependence should be taken into account for the evaluation of the crash safety of a lithium-ion pouch cell.

Original languageEnglish
Article number105906
JournalJournal of Energy Storage
Volume56
DOIs
Publication statusPublished - 1 Dec 2022

Keywords

  • Crash safety
  • Electro-mechanical failure behavior
  • Electrolyte influence
  • Lithium-ion batteries
  • Mechanical behavior
  • Out-of-plane direction dependence
  • Strain rate dependence

ASJC Scopus subject areas

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

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