Tube fit joining: A novel technique for busbar-to-prismatic cell interconnections in electric vehicles

This paper presents Tube-Fit Joining, a novel process for connecting prismatic cell terminals to busbars in EV batteries. It involves inserting a tubular connector into the terminal and busbar holes, followed by plastic deformation to establish force-fit and form-fit joints. This technique enables heat-free joining of dissimilar materials, reduces weight, and allows for easy disassembly for maintenance and recycling. Finite element simulations are used to analyse the joining mechanisms and assess structural integrity in shear tests. A dedicated tool is employed to implement the process and validate the numerical predictions. The results confirm that joint formation occurs in three distinct stages—bending, compression, and flange formation— with joining force increasing continuously throughout the process. Stress distribution analysis reveals that the force-fit joint develops during the compression stage, while the form-fit joint is primarily established in the final stage. The joint demonstrated a strength of 1 kN, with failure occurring at a displacement of 3.5 mm, resulting in damage to the connector but not the terminal, ensuring a reliable failure mechanism. In conclusion, the findings confirm the feasibility of Tube Fit Joining as a lightweight and efficient solution for prismatic cell interconnections in EV battery packs.