In-situ synchrotron X-ray computed tomography and multiphysics modeling of the failure mechanisms in an end-of-vehicle-life lithium-ion battery upon indentation

Lithium-ion batteries (LIBs) face safety and reliability challenges throughout service and retirement. However, the mechanistic relationships among mechanically induced structural damage, internal short-circuit (ISC) initiation, and subsequent thermal behavior remain insufficiently understood. This study presents an integrated experimental and computational framework for investigating structural evolution and ISC behavior in an 18,650 cylindrical cell subjected to quasi-static indentation. By integrating in-situ structural characterization with coupled multiphysics modeling, the framework correlates internal deformation and interfacial failure with ISC initiation and localized thermal responses. In-situ synchrotron X-ray micro- computed tomography and stepwise indentation enabled three-dimensional visualization of electrode deformation, layer interaction, and interfacial delamination in an end-of-life (EoL) cell. A finite element model examined the mechanical response and stress distribution of the multilayered cell architecture and identified failure-prone regions under spherical indentation. The model was calibrated against the measured mechanical response and observed deformation, providing a basis for subsequent mechanistic analysis. Building on the mechanically calibrated model, a coupled mechanical-electrochemical-thermal framework was established to clarify the progression from indentation-induced deformation to ISC initiation and subsequent heat generation at different states of charge. The results illustrate that enhanced ductility of the jellyroll components and improved interfacial cohesion can limit failure propagation across adjacent electrode and separator layers, thereby improving structural integrity and reducing ISC risk. Moreover, indentation-induced ISC can cause a pronounced localized temperature rise and heat accumulation even at 30% state of charge, indicating that the associated safety risk remains non-negligible even at low charge levels. The proposed framework provides experimentally grounded insight into mechanically induced battery failure and informs safer cell design, second-life applications, and recycling.