“We see a lot of laser welding and ultrasonic wedge bonding for the larger packs,” says Boyle at Amada Weld Tech. “If the packs or the overall volume are smaller, then resistance welding is often used. Micro-TIG comes up for specialised battery packs with low-volume production.
Laser welding is significantly faster showing the allure of the laser for battery module welding. Cycle time can be reduced even further with the use of a galvo scanning system, where some motion is handled by quick motions in the galvo head, and then indexed after all cells within the welding field are addressed.
“In these situations, cooperative development and reliable relationships are of high value.” While there many kinds of welding, in EV battery applications the most common are resistance welding and laser welding, along with ultrasonic welding and wire bonding, and benefit from standardisation for mass production.
Welding is a vitally important family of joining techniques for EV battery systems. A large battery might need thousands of individual connections, joining the positive and negative terminals of cells together in combinations of parallel and series blocks to form modules and packs of the required voltage and capacity.
Battery cells are most often put into modules or packs when produced for electrically driven vehicles. The variable of greatest influence when welding battery packs is the contact resistance between the cell and the connection tab. It is crucial to minimize this variable as much as possible to prevent energy loss in the form of heat generation.
The compared techniques are resistance spot welding, laser beam welding and ultrasonic welding. The performance was evaluated in terms of numerous factors such as production cost, degree of automation and weld quality. All three methods are tried and proven to function in the production of battery applications.