Investigation of corrosion and electrical resistance in laser welded Al-Cu joints for EV batteries

This study investigates the correlation among the microstructure, electrochemical, and electrical properties of laser-welded Al-Cu joints used in battery applications. Aluminium and copper thin sheets were laser welded at three power inputs (2000 W, 2100 W, and 2200 W), and joints were evaluated for their macro- and micro- structural features, corrosion behaviour, electrical resistance, and temperature rise during current supply. Results indicated that higher power inputs led to deeper weld penetration and increased intermetallic formation, impacting corrosion resistance and electrical characteristics. Electrochemical impedance spectroscopy (EIS), immersion, and Tafel tests confirmed that joints welded at 2200 W exhibited superior corrosion resistance than others, and this was attributed to a uniformly mixed Al-Cu region. The electric characteristics of the joints were assessed by supplying electric currents of 100 A, 150 A, and 200 A. In comparison to a weld joint developed at 2000 W, the electrical resistance of weld joints developed at 2200 W increased by 44.5 %, 37.87 %, and 39.31 % at 100 A, 150 A, and 200 A current supplies, respectively. Electrical resistance measurements revealed a direct correlation with weld quality and temperature rise, with implications on battery performance. These findings underscore the critical role of joint quality in optimizing battery performance.