Mechanical Behaviour of Tube Fit Joints in EV Battery Systems: The Role of Material Selection

Tube-fit joining is a promising heat-free solution for busbar-to-prismatic cell terminal interconnections, offering rapid disassembly for repair, reuse, and recycling. This study experimentally investigates the mechanical behaviour of tube-fit joints under pull-out and shear loading, considering different joining forces and busbar–terminal material combinations. Increasing the joining force from 10 to 16 kN enhanced connector deformation and mechanical interlocking, resulting in a pronounced improvement in pull-out performance but only a limited change in shear capacity. A joining force of 13 kN provided the most suitable balance between mechanical performance and damage-free disassembly. Under pull-out loading, the response was primarily governed by the busbar material: copper busbars produced higher peak loads and larger displacements, whereas aluminium busbars exhibited stiffer responses and shorter pull-out strokes. Under shear loading, the different material combinations showed comparable peak loads and a predominantly connector-driven failure mechanism, indicating that shear capacity was mainly controlled by the connector. Increasing the aluminium busbar thickness enhanced joint stiffness and shear load capacity without changing the governing failure mechanism. Overall, this work provides new insights into the interplay between material selection and process parameters in tube fit joining, offering valuable guidance for the design of robust, disassemblable interconnections in next-generation EV battery systems.