Parametric study of pulse arc welding (PAW) and laser beam welding (LBW) techniques for electrical vehicle battery cells

Electrical vehicles (EV) offer the automotive industry the potential to meet future emission targets by developing large battery systems. These battery systems require several thousand single battery cells to be connected together. The battery cells are complex assemblies of dissimilar materials with very low thicknesses, which presents a significant challenge during the joining process, especially welding. We have investigated the performance of laser beam welding (LBW), as well as pulsed arc welding (PAW) for joining 0.3mm thickness nickel coated copper to 0.7mm thickness mild steel. The parametric study for good quality lap welds based on high tensile strength, was performed. The weld microstructure was investigated using optical, as well as scanning electron microscopy (SEM). The mechanical performance of the weld samples was characterized through tensile testing and micro hardness measurements to establish the microstructure property relationship. The maximum tensile strength measured for specified weld geometries was 660N for LBW and 496N for PAW. A significant increase in the hardness was measured in the weld nugget due to the formation of Cu-Fe composite microstructure.