Battery manufacturing has emerged as one of the most intensively researched domains in the modern electric vehicle (EV) industry, where the quality of interconnects critically influences performance from the individual cell through module assembly to the final battery pack. Ultrasonic welding (UW) stands out as a leading solid-state joining technology for EV battery packs, combining high process efficiency, negligible thermal distortion, and durable electrical joints. Mainly effective for dissimilar materials such as aluminum-copper, and aluminum-steel, UW strengthens reliability, safety, and cost-effectiveness in high-volume EV production. Drawing on an in-depth survey of recent research, technical publications, and industrial case studies, this paper presents a state-of-the-art review of ultrasonic welding for EV battery pack assembly. It highlights the underlying physical principles, key process parameters, and principal advantages of UW, while critically evaluating tenacious challenges related to material compatibility, joint integrity, and long-term durability. Special emphasis is placed on how joint performance determines electrical conductivity, mechanical strength, and corrosion resistance under demanding EV operating conditions. The review further outlines cutting-edge advances in process monitoring, in-line quality assurance, and multi-objective optimization strategies that improve weld consistency, pack safety, and sustainability. It also evaluates barriers to wider industrial adoption such as repeatability at scale, inspection complexity, and standardization gaps and pinpoints how recent innovations in control systems and equipment design are helping to overcome them. Finally, the paper summarizes emerging trends in smart UW systems, hybrid joining concepts, and AI/ML-enabled process optimization, pointing to clear future research directions for next-generation EV battery manufacturing.
Kumar et al. (Wed,) studied this question.