Parametric Study of Spot Welding between Li-ion Battery Cells and Sheet Metal Connectors

This work was designed to study the effects of influencing parameters in series/parallel gap spot welding process and determine the optimized parameters setting for spot welding between 18650 Li-ion battery cells and sheet metal connectors. The welding parameters that were studied in this work include electrode tip geometry, connecting strip material and design, maximum supply voltage, welding time welding force and distance between two electrodes. The effects of these parameters were investigated via simulations and experimentations. A sample battery cell was disassembled and measured to create the 3D models. Simulations were carried out software to observe the deformation, electric current distribution as well as temperature distribution occurred within the models. For experiments done in this work, the actual spot welding was conducted using the Miyachi FD120 series spot welding machine. The trial welding was first performed between two different thicknesses of Hilumin (R) connecting strips themselves. Then, after having the results of studied parameters from both simulations and experiments compared and analyzed, the actual spot welding was conducted between Hilumin (R) connecting strips and both of positive and negative terminals of SAMSUNG INR18650-15L Li-ion battery cells. The electric resistance and mechanical strength of the welded contact were measured. Finally, the suistriple welding parameter setting ranges were obtained as a result, which can be applied to create battery packs either from the similar or other different models of 18650 Li-ion cells via series spot welding processes.