Dissimilar laser welding of high-thickness Cu/Al plates for high-current density electrical batteries

Electrical batteries connecting is a crucial phase in the fabrication of electrical vehicles. It is usually performed using high-quality lasers focused on narrow spot, to overcome the low optical absorptivity of copper and/or aluminum and displaced with high-speed scanner to accomplish the production rate. In applications where the current density is high (naval, heavy transport, etc) the busbars used for the electrical connections are thick (0.8-1 mm) increasing the difficulties of having joints with no defects. In this paper, an in-depth analysis of the impact of laser power, welding speed, and innovative scanning strategy on joint quality is presented for lap welding of nickel-plated copper (0.8 mm) to AA1050 alloy (3 mm). Process optimization involves achieving the desired weld area while controlling metal-mixing indices to limit the formation of brittle intermetallic compounds, cracks and voids. Weld joint quality assessment, including metallographic examination, microhardness tests and SEM- EDX analysis is presented and discussed