Review of the advancements in aluminum and copper ultrasonic welding in electric vehicles and superconductor applications

Ultrasonic welding (UW), a most promising solid-state welding technique, is being developed for the automotive industry, more specifically, for joining components in electric vehicle batteries. It has also been used in rare-earth barium copper oxide (REBCO)-based superconductors, which have different stabilizing materials. At present, challenges remain when using UW to join aluminum (Al) and copper (Cu) in either application, and research in these areas are undeniably important for the future use of fully in-line UW applications. This paper provides a review of the current status of UW for joining Al and Cu, specifically in electric vehicle batteries and REBCO-based superconductors. Important issues about process characteristics and critical concerns about weld parameter optimization, joint structure morphology, temperature measurements, joint mechanical properties, and quality of the joints are addressed. Modeling and simulations using the finite element method in predicting the physical phenomena in the dynamic UW process are discussed. The status of electromechanical behaviors in ultrasonically welded joints in superconductors is detailed. Lastly, guidelines and valuable knowledge for the integration of Al and Cu UW in electric vehicle battery assembly and superconductors are provided as a basis for future research directions in these fields.