Welding is a vitally important family of joining techniques for EV battery systems. A large battery might need thousands of individual connections, joining the positive and negative terminals of cells together in combinations of parallel and series blocks to form modules and packs of the required voltage and capacity.
Brass (CuZn37) test samples are used for the quantitative comparison of the welding techniques, as this metal can be processed by all three welding techniques. At the end of the presented work, the suitability of resistance spot, ultrasonic and laser beam welding for connecting battery cells is evaluated.
Different welding processes are used depending on the design and requirements of each battery pack or module. Joints are also made to join the internal anode and cathode foils of battery cells, with ultrasonic welding (UW) being the preferred method for pouch cells.
The search was then performed using Uppsala University’s Library database and Google scholar which cover a wide range of articles and sources. Three methods for welding batteries were given in the template, being laser beam-, ultrasonic-, and resistance spot welding.
The findings are applicable to all kinds of battery cell casings. Additionally, the three welding techniques are compared quantitatively in terms of ultimate tensile strength, heat input into a battery cell caused by the welding process, and electrical contact resistance.
4.1.2 Effect on the battery cell Small-scale resistance welding is often the preferred method for joining Li–ion batteries into battery packs. This process ensures strong joints with an almost complete elimination of the heat impact on the joined workpieces during a short time.