Joining multiple-layer Al-Cu thin foils by a novel Resistance Rolling Welding method for battery application

Abstract

A novel resistance welding method called Resistance Rolling Welding (RRW), in which a roller upper electrode and a flat lower electrode were adopted, was developed to realize a long-distance, large-area and multiple-layer Al-Cu welding with a flat weld surface. In this study, three Al layers and a single Cu layer were joined by RRW via various mechanisms. The Al layers adjacent to the Cu layer were joined due to Al2Cu intermetallic compound generation via Al melting and Cu diffusion, while those far away from the Cu layer were joined owing to the dynamic recrystallisation caused by the large deformation and high welding temperature. With increasing the welding current from 6 kA to 10 kA, the peak load of joints in the coach-peel test first increased up to the maximum, then decreased. The electrical resistance of the entire joints and the corresponding interlamination resistance for each interface showed the similar tendency: first decreased then increased with the increasing currents. A sound dissimilar joint with the highest coach-peel load (185.25 N) and the relatively lower electrical resistance was thus obtained at 9 kA via RRW.