<p>Recent uptake of electric vehicles (EVs) has demanded several technological advancements including joining of high-volume battery interconnects with low cycle time. Laser welding is being used as the technology of choice due to precise, one-sided, non-contact joining for faster manufacturing. At present, infrared (IR) lasers are being used for producing Li-ion battery interconnects where highly conductive and reflective copper (Cu) and aluminium (Al) are to be welded. IR lasers suffer from low absorptivity, irregular penetration depth, formation of brittle/highly resistive intermetallic compounds (IMCs) for dissimilar metal welding, and weld defects. In contrast, blue lasers are emerging as a technological advancement which offers several benefits, including efficient penetration depth control, low weld defects and improved joint strength. This paper investigates blue laser welding to produce similar and dissimilar Cu/Al tab-to-tab interconnects with/without Ni interlayer at different stack-up conditions using an 800&#xa0;W blue laser. While Cu-Cu and Al-Al joints exhibited higher tensile load (i.e., 675.4&#xa0;N and 453.5&#xa0;N, respectively), the Cu-Al and Al-Cu joints suffered from a low peak load due to the formation of brittle IMCs. By using a Ni-foil as an interlayer (Cu-Ni-Al), tensile load was improved by 12.36% in comparison with the Cu-Al joint. Microstructural behaviours, micro-hardness mapping, and an in-depth study of IMCs formation showed their correlation with the joint strength. In addition, joint resistance and temperature rise due to the application of representative charge/discharge currents showed the suitability of blue laser welded joints for EV battery applications.</p>