In the attempt to produce lighter battery packs at lower cost, replacing common copper parts with aluminium components has been a popular approach in recent years. With regards to joining technologies, there is a growing interest in applying laser beam welding in battery manufacturing due to several advantages such as single-sided and non-contact access, whilst maintaining a narrow heat affected zone. Motivated by the need to control and reduce weld porosity in AA1060 battery busbar welding with the ultimate goal to enhance durability and reduce electrical resistance, this paper has been developed with the aim to study the mechanisms of porosity formation and implement a novel beam shaping approach to reduce the volumetric pores distribution. Porosity formation is attributed to two mechanisms: metallurgical porosity caused by chemical reactions and process porosity related to the instability of the keyhole and fast solidification rates. In this study, a multi-physics Computational Fluid Dynamics (CFD) model has been developed and calibrated to study the effect of a circular and a tailing laser beam shape on melt pool dynamics and evolution of porosity due to instability of the keyhole, and hence generate knowledge about the underlying physics of the welding process itself. The study will discuss roots of actions for optimisation of weld quality via integration of laser beam shaping lens in “off-the-shelf” welding heads.