Laser welding is a key enabling technology the transition towards electric mobility, enabling joints with elevated electrical and mechanical properties. In the production of battery packs, cell to busbar connections are challenging due to the strict tolerances and zero-fault policy. Hence, it is of great interest to investigate how beam shaping techniques may be exploited to enhance the electro-mechanical properties as well as improve material processability. Industrial laser systems often provide the possibility to oscillate dynamically the beam or redistribute the power in multi-core fibers. Although contemporary equipment enables elevated flexibility in terms of power redistribution, further studies are required to indicate the most adequate solution for the production of high performance batteries.
Within the present investigation, both in-source beam shaping and beam oscillation have been exploited to perform 0.2-0.2 mm Ni-plated steel welds in lap joint configuration, representative of typical cell to busbar connections. An experimental campaign allowed to define process feasibility conditions where partial penetration welds could be achieved by means of in-source beam shaping. Hence, dynamic beam oscillation was explored to perform the connections. In the subset of feasible conditions, the mechanical strength was determined via tensile tests alongside electrical resistance measurements. In-situ high speed videography allowed to disclose the process dynamics. Linear welds with a Gaussian beam profile enabled joints with the highest productivity at constant electro-mechanical properties. Spatter formation due to keyhole instabilities could be avoided by redistributing the emission power via multi-core fibers whilst dynamic oscillation did not provide significant benefits.