SoniLaser – Ultrasonic assisted laser welding for high volume assembly of automotive battery packs

EV sales will reach 44 million vehicles per year by 2030 with many European countries, including the UK, aiming at zero emissions within the next 30 years. Therefore, there is an increasing need for manufacturing of battery packs to meet demand and whilst Asia remains the stronghold (projected to reach 800GWh by 2025), Europe is expanding rapidly with a projected production capacity of 450GWh/year by 2030\.

Laser welding has emerged as the optimal welding technique to respond to the increasing demand for EV battery manufacturing, being 4-5 times faster than the current welding processes. While laser welding is well suited to the increasing manufacturing demand and the joining needs of the battery pack assembly, challenges to its application in this industry remain. Typically, a standard battery pack consists of hundreds, even thousands, of individual cells which are connected to deliver the required power and capacity. Making the required joints represent several metallurgical challenges, including, joining of multiple dissimilar materials of varying thicknesses.

The differences in thermal, physical, and chemical properties between dissimilar materials pose a series of challenges that must be addressed before widespread application of laser welding can be realised in the battery manufacturing sector. The low miscibility between dissimilar materials leads to a poor weld metallurgical compatibility, which is further exacerbated by large differences in thermophysical properties. Hot cracks, porosity, incomplete fusion, and other defects are usually introduced. A variety of intermetallic compounds (IMCs) can also form within the weld zone during solidification of dissimilar joints. The formation of such hard and brittle IMCs can severely deteriorate the mechanical properties of the welded joints. Controlling the formation of intermetallic compounds and their thickness, minimising weld defects has become a prominent research topic in the battery manufacturing/assembly industry. SoniLaser will offer a ground-breaking solution for the EV battery manufacturing sector through the integration of a power ultrasonic vibration subsystem to assist the laser welding process of various parts of the battery. Consortium partners have previously demonstrated that applying a power ultrasonic vibration during the laser welding process, can induce a 25% reduction in weld defects (pores, cracks) and 30% mitigation of IMCs leading to at least 10% increase in mechanical strength of the welded joints. SoniLaser will be provided as a retrofittable bespoke solution, customised to the laser welding equipment of each client and to each production line segment, increasing their current speeds more than 50%.