Utilising blue laser over infrared laser to enhance control of penetration depth and weld strength for producing electric vehicle battery interconnects

• Published in: Journal of materials processing technology Vol. 317; p. 117989
• Main Authors: Dhara, Sisir, Finuf, Mathew, Zediker, Mark, Masters, Iain, Barai, Anup, Das, Abhishek
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2023
• Subjects: Battery tab/busbar interconnects; Blue laser welding; IR laser welding; Tensile performance; Weld microstructure; Weld microstructure; Battery tab/busbar interconnects; Blue laser welding; IR laser welding; Tensile performance
• ISSN: 0924-0136
• DOI: 10.1016/j.jmatprotec.2023.117989

This paper focuses on a comparison of mechanical and metallurgical behaviours of lap joints welded by a blue laser system (at ∼450 nm wavelength) and infrared (IR) laser system (at ∼1070 nm wavelength). The feasibility and applicability of both lasers for producing tab-to-tab and tab-to-busbar interconnects considering dissimilar material stack-ups were evaluated. The joints produced with both types of laser system were examined for microstructural evaluation at fusion zone and joint strengths during lap shear/T-peel tests and failure mode analysis at the fracture surfaces. Penetration depth was considered as the important attribute for characterising the microstructural evaluation at fusion zone. This study reports that IR laser of 200 µm spot size is not suitable for highly reflective materials joining, whereas blue laser of the same spot size demonstrated the capability of joining thin as well as highly reflective materials. Using a blue laser, penetration depth and subsequent joint strength can be easily controlled. This was supported by elemental analysis and micro-hardness study at weld interface. Contrarily, IR laser showed inability to control the penetration depth which hindered the effective control of the joint strength. It was either no weld or full penetration weld with porosity and cracks. This work unprecedentedly revealed that the blue laser could be effectively employed for joining copper to steel and copper to aluminium for Li-ion battery interconnects in electric vehicles. On the other hand, the applicability of IR laser to join copper to steel and copper to aluminium for Li-ion battery interconnects was limited.