Laser beam welding of copper foil stacks using a green high power disk laser

A major challenge in the manufacturing of lithium-ion batteries is the qualification of a production system that is able to provide the high quality requirements of the cells. For internal contacting, the demands on the joining process are very high due to the low foil thicknesses and the temperature sensitivity of the battery components. Currently used joining methods, like ultrasonic welding, have limitations, such as the risk of mechanical damages. Laser beam welding is a promising approach based on the contactless process principle. In this paper, process experiments on the laser beam welding of copper foils using a beam source emitting at a green wavelength are described. Stacks of 30 copper foils with a thickness of 10 µm each were welded. Different process strategies were applied and compared. The weld seams were evaluated by means of cross sections and topographic analyses. The investigations showed promising results using a beam source emitting at a green wavelength for the joining of foil stacks.