Coupling X-ray computed tomography with digital volume correlation to study core collapse in lithium-ion batteries

Abstract

This study investigates the link between internal cell features and mechanical behaviour of commercial cylindrical lithium-ion batteries (LIBs), which impacts both safety and performance. X-ray computed tomography is combined with digital volume correlation to study the core collapse mechanisms of LIBs during cycling. Detailed correlations between volumetric strain distribution and internal mechanical features, such as the positive tab, negative tabs, and kinks, were identified. Complex, heterogeneous swelling takes place within consistent vertical localised bands that correlate with the position of key internal features. The novel data analysis approach also provides insights into the changes in shape of the jellyroll during cycling. The heterogeneous deformation of the cells resulted in wrinkling and buckling of the jellyroll, which was reproduced and correlated to local tensile/compressive strains developing around the innermost layers. This approach can be used to understand the impact of cell design features on core collapse and provide strain data to validate numerical mechanical models.