Laser welding of Li-ion battery electrical contacts exploiting core/ring beam shapes

The growing demand for electric vehicles has increased the need for high-performance batteries, where reliable joining of delicate components is essential. Laser technology has emerged as an effective solution, particularly with recent advancements enabling spatial modulation of the beam intensity profile. In this work, a 5 kW multimode, multicore infrared fiber laser is employed to investigate the impact of varying the ring power distributions and welding speed. The study utilizes thin copper and aluminum samples arranged in an overlap configuration to simulate the internal contact between the tabs and the electrode roll. A partial penetration weld is required to prevent damage to the inner battery components, and cross-sectional, mechanical, and electrical analyses are conducted to evaluate the impact of process parameters on bead quality. Additionally, a photodiode-based acquisition system is employed to detect variations in weld classifications and process drifts. The results support the possibility of increasing the resistance area of partially penetrated weld seams by modulating the spatial beam intensity profile across the concentric rings while keeping the core power constant. Experiments show that distributing power toward the external rings is capable of producing weld beads characterized by a peak load of approximately 300 N for both the considered materials. Moreover, the available power enables high productivity rates, allowing welding at speeds where the closest Gaussian beam distribution would be ineffective.