21.03.2016 | Battery Technology

Automated tab welding

A precise and flexible laser welder automates the assembly of prismatic lithium-ion cells to battery packs and makes the process reliable, reproducible, efficient and cost-effective. Both the mechanics and the control and drive technology can be adapted to different production tasks.

The advantage in experience of Asian companies in the development and manufacturing of consumer lithium-ion cells has ultimately meant that the majority of local battery manufacturers do not develop their own capacity. The majority of European automobile companies and their system suppliers are currently more focused on follow-up processes. Common practice is to procure finished battery cells and then to assemble these into battery packs. Anyone wishing to produce the expected increasing quantity at the highest quality and competitive cost must automate assembly and develop a stable, reproducible and cost-effective process.

Jonas & Redmann has developed an automatic laser welder for joining tabs of prismatic cells which exactly fulfills these requirements. The machine can be used flexibly for various welding tasks in product development and is equally suited for production at an industrial scale. For pure serial production, the approach can be further simplified and optimized.

Fine, secure and low-loss – laser welding preferred

Laser welding enables extremely fine, permanently secure and low (electrical) loss joints, which has been confirmed in advance tests. The intended primary application – welding many thin aluminum and copper tabs – requires a high-performance laser system with extremely precise focus. In particular, the welding depth must be reproducibly adjustable to within a few micrometers so that only the desired material layers are welded. Jonas & Redmann implemented this with a 6 kW fiber laser with a spot diameter of 140 µm.

Precise, dynamic and flexible – a mechanism with many degrees of freedom

The mechanism must be correspondingly stiff and precise, and the laser head must be flexibly and dynamically positionable within the workspace (±440 mm (X) / ±540 mm (Y) / ±150 mm (Z)). The laser head is mounted on a gantry, is servomotor driven in three axes, and can be swiveled by ±30° in the direction of transport. This means that every point in the workspace can be reached by the laser head with a precision of ±0.02 mm. The laser optics have their own control mechanism and can be NC driven in three axes. With this, high-precision elevation profiles can be mapped, whereby the welding depth can be exactly and reproducibly controlled using both the speed of travel and laser power.

Contact at Jonas & Redmann:

Oliver Zink
R & D, Division Energy Storage

Elke Beune
Corporate Communication
030 230 866-6823