WELDABILITY AND THICKNESS STUDY OF ELECTROLESS NICKEL COATING ON ALUMINIUM CONDUCTOR FOR LI-ION BATTERY PACK

Abstract

Aluminium (Al) is used as an electrical conductor for battery modules to reduce the cost of battery modules but still provides high performance. An electroless nickel (EN) coating is applied to the surface of the Al conductors to meet the mentioned requirements, as it is well known in the automotive industry for its hardness and wear resistance. This paper presents a novel study on the influences of EN thickness on the weldability between the EN coated Al conductors and the tin coated copper wires using resistance spot welding (RSW). The two main parameters of this study are nickel (Ni) thickness and Al thickness. A total of twelve thickness conditions of the material are used. It consists of three differences in the thickness of Al; 2, 3 and 4 mm, that their surfaces are coated by four different thicknesses of Ni; uncoated, 10 µm, 20 µm and 30 µm. The electrical conductivity, the pull force and the peel force are measured after the specimens are welded with the tin coated copper wires. Poor and good weldabilities are studied to discover the cause of the behaviours. This study assists the primary purpose of using Al as the electrical conductor for battery modules, reducing the cost of battery modules but still offering high performance.