Microstructural and Joint Analysis of Ultrasonic Welded Aluminum to Cupro-Nickel Sheets for Lithium-Ion Battery Packs

Energy crisis poses a major challenge in the modern industrial scenario. A critical aspect of the shop floor work includes the welding of dissimilar metal sheets which require the right amount of energy. In order to tackle these challenges, a conservative and energy efficient method are necessary. Recently, automotive industries have been widely adopted the ultrasonic metal welding process for assembling lithium-ion battery packs and its modules. The joining of these dissimilar metals using any other conventional welding process is extremely challenging due to varying physical, chemical, thermal properties, the formation of the heat affected zone and lesser bond strength. However, ultrasonic metal welding yields better quality welds under the influence of optimal parametric conditions. In this research, the weld quality of two dissimilar materials, namely, aluminum (AA1060) with cupronickel (C71500) sheets investigated at different welding time, vibration amplitudes and welding pressures with a fixed ultrasonic frequency of 20 kHz. Experimental results show the tensile shear strength of the weld is maximum at the highest vibration amplitude with a moderate amount of weld pressure and weld time. Additionally, the joint quality and its associated microstructure at the weld region are analyzed by scanning electron microscopy (SEM) to reveal the bond strength with the interlocking feature.