Spatially Modulated Laser Beam Micro Welding of CuSn6 and Nickel-plated DC04 Steel for Battery Applications

Lithium-ion battery cells are being increasingly used as energy storage devices for electrically powered vehicles on account of their high energy density. 18650-type cells provide an ideal solution thanks to their low price and ready availability. Compared with large-format cells, however, these cells have low capacity, which is why several individual cells have to be connected in parallel to create larger cells or suitable battery packs. In these cases, overlap welding is commonly used to join a copper current collector and battery can -the negative pole -made out of nickel-plated DC04 steel. The major challenge in welding batteries is melting both parts without damaging the can and causing the electrolyte to leak. Spatial modulation can be used to control weld depth very precisely. In this paper, we present recent developments in spatial modulation of laser radiation for welding the material combination of copper and steel in the field of battery welding and discuss the influence of the modulation amplitude. Also, we show the extent to which tensile strength influences the joint and the electrical resistance.