A novel integrated process-performance model for laser welding of multi-layer battery foils and tabs

In this work, a novel, integrated multi-physics process-performance modeling approach for multi-layered copper laser welds is developed and validated. A new Reduced Fluid Fraction Region (RFFR) method for modeling the laser welding of thin foils stack-ups with air gaps has been created as part of this approach. The approach consists of two modeling steps, both of which are experimentally validated. First, the laser welding process was predicted using a Computational Fluid Dynamics (CFD) model, the results of which were validated against laser weld dimensions from experiments. Second, the structural performance of the CFD simulated welds was predicted using a Finite Element Analysis (FEA) model, the results of which were validated against lap-shear force-displacement results of experimental welds. Two stack-ups, i.e., tab-tab (two 0.2 mm thick Cu tabs) and foils-tab (30 layers of 9 μm thick Cu foils and one 0.2 mm thick Cu tab), served as test cases and were simulated and validated for a variation of laser welding process parameters. Results demonstrated that predictions of both stack-ups matched experiments well, in terms of the weld dimensions, force-displacement response, failure mode, and the presence of weld undercuts. The results of this work enable the simulation of multi-layer stack-ups with thin foils by tackling the problem of air gaps in laser welding. These simulations also enhance the understanding of mechanisms behind the laser welding process and weld performance and have important applications in endeavors such as the design and manufacturing of battery electric vehicles.