Investigations on laser beam welding of thin foils of copper and aluminum regarding weld seam quality using different laser beam sources

Nowadays, there is a strong and growing ambition to switch from combustion technology to battery-electric drives, and energy storage is spotlighted. Laser beam welding is an appropriate and favorable welding technology in battery production. Due to the high welding speed, the local heat input, the contact freeness efficient, and automatable processes can be established. Materials used in batteries for electrodes that have to be connected are commonly copper and aluminum. Specifically, copper is highly reflective for widely used infrared laser beam wavelengths. Furthermore, the thickness in the area of 10 μm is quite challenging to deal with, in terms of gap free clamping and avoidance of damage to the material as well as distortion during welding. There is a fine line regarding energy input between burning the material and generating a lack of fusion. In the presented research, welding approaches with different laser beam sources emitting laser beams with infrared wavelengths, various beam shapes, and welding modes (continuous and pulsed) are studied. A total of 40 copper foils with a thickness of 10 μm and 40 aluminum foils with a thickness of 15 μm are welded to similar sheet metals. Aim of the process development are welds with high quality and high connection widths to provide the best electric conductivity.