Automotive battery pack manufacturing – a review of battery to tab joining

Automotive battery packs used for electromobility applications consist of a large number of individual battery cells that are interconnected. Interconnection of the battery cells creates an electrical and mechanical connection, which can be realised by means of different joining technologies. The adaption of different joining technologies greatly influences the central characteristics of the battery pack in terms of battery performance, capacity and lifetime. Selection of a suitable joining technology, therefore, involves several considerations regarding electrical and mechanical properties and an assessment of production and operational conditions. Particularly, during the operation of an electric vehicle, challenges and mutual dependencies of the electrical and mechanical system emerge. The present work provides an overview of interdisciplinary challenges occurring at joints which are exposed to electrical current with a strong focus on interconnecting batteries for electric cars. It summarizes common quality criteria for the joining technologies and recombines those with criteria deduced from an electrical engineering point of view. Scientific literature concerning different joining technologies in the field of battery manufacturing is discussed based on those criteria. The most common joining techniques are ultrasonic welding, wire bonding, force fitting, soldering, laser beam welding, and resistance welding. Besides those, friction stir welding, tungsten inert gas welding, joining by forming and adhesive bonding are presented.