JOINING OF LITHIUM-ION BATTERIES USING LASER BEAM WELDING: ELECTRICAL LOSSES OF WELDED ALUMINUM AND COPPER JOINTS

摘要

Lithium-ion batteries are preferred in electric and hybrid-electric vehicles due to their high energy density. In the course of developing battery systems which consist of several hundred cells, the energy efficiency still needs to be increased. A promising measure to reduce electrical losses is the contact between cell terminal and cell connector. In order to reduce these electric losses, laser beam welding is applied to achieve material locking connections with low contact resistances. This paper presents the investigation of contact resistances of cell connectors joined by laser beam welding. Starting with a theoretical outline of the occurrence of electrical contact resistances, a testing method is proposed to measure contact resistances of material locking joints. The influence of different welding parameters on the contact resistance is evaluated within a comparative study. The results of this study are further discussed by means of metallographic cross section polishes.