Electric energy storage spot welding

What is resistance spot welding?

Resistance spot, ultrasonic or laser beam welding are mostly used for connecting battery cells in the production of large battery assemblies. Each of these welding techniques has its own characteristics depending on the material properties and contact geometry. Cell casing and terminal dimensions may constrain possible contact geometries.

Why is welding important for EV battery systems?

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.

Why is spot welding of cuzn37 difficult?

As already discussed in Section 3, spot welding of CuZn37 generates voids inside the weld nugget and, therefore, higher electrical contact resistances as well as lowest ultimate tensile forces were measured. A possible stray current might pose another difficulty for further weld spots, when some weld spots are already made in close vicinity.

How does welding energy affect electrical contact resistance and tensile force?

Further increasing the welding energy leads to electrode sticking and significant expulsion of bulk material , , , . Fig. 6. Electrical contact resistance and ultimate tensile force as function of welding energy.

Why are battery contacts so difficult to weld?

At the highest level, reliability and process speed are the main engineering challenges in welding battery contacts and structures, he notes. Carr concurs, and cites cost and customers’ desire to use the latest materials, such as grades of aluminium that are super-light but hard to weld and seal shut.

Should you use resistance welding or micro-Tig?

“If the packs or the overall volume are smaller, then resistance welding is often used. Micro-TIG comes up for specialised battery packs with low-volume production. “Recent developments in galvo scanning, beam steering and process monitoring allow for faster speeds and improved process error detection, respectively,” he adds.