Core Collapse Instability of Spirally Wound Jelly-Roll Lithium-Ion Batteries

Abstract Background Cylindrical lithium-ion batteries are tend to have an inward deformation during charge and discharge, which is called “core collapse”. This structural instability remains poorly quantified, and a deeper understanding of the underlying mechanics is essential for improving the structural integrity and safety of rechargeable cells. Objective This study aims to investigate the deformation and buckling mechanisms of cylindrical lithium–ion battery jelly rolls under electrochemical cycling, with a focus on the interplay between geometry, interfacial constraint, and internal stress evolution. Methods X-ray computed tomography (CT) imaging was employed to characterize the three-dimensional deformation of commercial cells, while a detailed finite element (FE) model explicitly incorporating current collectors, coating layers, and separators was developed to simulate chemo-induced stresses. The lithiation and delithiation processes were represented through an equivalent thermal-expansion surrogate to evaluate pre-buckling stress states. Results CT analysis revealed negligible volumetric and hoop strains, confirming strong geometric constraint from the spiral architecture. Simulations showed that interface compatibility between current collectors and electrodes governs hoop-dominated stress fields, and that separator wrinkling can precede electrode buckling due to low bending stiffness and expansion mismatch. Conclusions The results elucidate how hoop compression, interface constraint, and structural asymmetry collectively trigger jelly-roll instability. The findings establish a mechanistic foundation for analyzing confined expansion and guiding future multi-physics modeling of battery structural reliability.