Effect of weld profile geometry on dissimilar laser welded joints for battery applications

Abstract

A transition from fossil fuels to greener technologies like batteries is essential for a sustainable future. This study explores the impact of weld profile geometry on laser-welded aluminum–copper (Al–Cu) dissimilar lap joints at a constant power input of 2.1 kW, relevant for bus-bar connections in electric vehicle battery manufacturing. Two weld profiles: parallel line and circular, were compared in terms of microstructure, mechanical strength, electrical resistance, and corrosion behavior of the joints. Microstructural analysis showed that the circular weld exhibited deeper penetration and a wider Al2Cu intermetallic layer, while the parallel profile had a thinner, sharper, and uniform interface. Mechanical tests indicated that the circular profile achieved 66% higher peak load and better ductility. It also showed lower electrical resistance and reduced temperature rise under currents of 50 A, 100 A, and 150 A, suggesting improved conductivity than parallel line weld. However, electrochemical testing revealed higher corrosion current density and severe interfacial degradation in the circular profile due to its broader, uneven intermetallic zone. The findings emphasize that weld profile geometry significantly influences joint behavior, and optimized weld design can enhance performance without increasing power input, particularly relevant for battery interconnects and lightweight electronic applications.