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Progressive mechanical indentation of large-format Li-ion cells

Large format Li-ion cells were used to study the mechanical responses of single cells of thickness 6.5 mm and stacks of three cells under compressive loading. Various sequences of increasing depth indentations were carried out using a 1.0 inch (25.4 mm) diameter steel ball with steel plate as a rigi...

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Bibliographic Details
Published in:Journal of power sources 2017-02, Vol.341, p.156-164
Main Authors: Wang, Hsin, Kumar, Abhishek, Simunovic, Srdjan, Allu, Srikanth, Kalnaus, Sergiy, Turner, John A., Helmers, Jacob C., Rules, Evan T., Winchester, Clinton S., Gorney, Philip
Format: Article
Language:English
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Summary:Large format Li-ion cells were used to study the mechanical responses of single cells of thickness 6.5 mm and stacks of three cells under compressive loading. Various sequences of increasing depth indentations were carried out using a 1.0 inch (25.4 mm) diameter steel ball with steel plate as a rigid support surface. The indentation depths were between 0.025″ and 0.250″ with main indentation increments tests of 0.025″ steps. Increment steps of 0.100″ and 0.005″ were used to pinpoint the onset of internal-short that occurred between 0.245″ and 0.250″. The indented cells were disassembled and inspected for internal damage. Load vs. time curves were compared with the developed computer models. Separator thinning leading to the short circuit was simulated using both isotropic and anisotropic mechanical properties. Our study show that separators behave differently when tested as a single layer vs. a stack in a typical pouch cell. The collective responses of the multiple layers must be taken into account in failure analysis. A model that resolves the details of the individual internal cell components was able to simulate the internal deformation of the large format cells and the onset of failure assumed to coincide with the onset of internal short circuit. •Single-side mechanical indentations were performed on large format Li-ion cells.•Progressive indentations using 0.025 inch steps to study cell and cell stack deformation.•Simulation of mechanical deformation of cells matched with experimental results.
ISSN:0378-7753
1873-2755
DOI:10.1016/j.jpowsour.2016.11.094