Laser Welding for Battery Tabs and Busbars
Joining Pure Nickel Without Heating the Cell
A lithium cell is a sealed chemical system with a temperature limit, and every tab joined to it is a chance to exceed that limit. Laser welding puts the energy where the joint is and nowhere else: the pulse lasts milliseconds, the fused zone is a fraction of a millimetre across, and the can below it never reaches a temperature that damages the jelly roll or the seal. That is the whole reason pack builders reach for it — not speed, but the ability to make a sound joint in pure nickel at full thickness while leaving the cell alone.
Why pure nickel resists the spot welder
Resistance spot welding works by putting a current through a joint that resists it. Pure Nickel 200 has a resistivity of about 8.5 µΩ·cm against nickel-plated steel's 20+ µΩ·cm — the property that makes it the better conductor in a finished pack is exactly the property that makes it hard to spot weld. The current takes the easy path, the heat appears in the cell rather than at the interface, and the answer on a spot welder is more energy, which is the last thing a cell should be given. Builders who work around it by dropping to thinner strip or to plated steel give up the low resistance they were buying nickel for. A laser does not depend on the workpiece resisting anything, so pure nickel strip can be joined at the thickness the pack actually needs.
What we weld
- Tab to cell: pure nickel tabs onto the caps and cans of cylindrical cells — 18650, 21700, 26650 and 32650 / 32700.
- Strip to busbar: series and parallel links between H-type, honeycomb and zig zag busbars and the strip that carries the current between groups.
- Dissimilar joints: nickel to copper, including tabs onto nickel-copper sandwich busbar and copper busbar, where the nickel face is what gets welded.
- Fusing links: the narrow sections cut into a busbar to act as a fuse, welded without annealing the very feature they were cut for.
Materials and certification
We weld the material we stock: Nickel 200 and Nickel 201 to ASTM B162 (UNS N02200 / N02201), copper busbar, and nickel-clad copper. Because the strip and the weld come from the same place, the EN 10204 3.1 mill test certificate for the material follows the job through processing rather than stopping at the despatch of a coil — the pack builder gets one traceable chain, not two.
Thickness, joint configuration, cell format and pitch are quoted against your pack drawing at the time of enquiry. We would rather answer for your layout than publish a range that turns out not to cover it.
Laser welding against resistance spot welding
Both have their place, and most packs use both. The table is the short version of when the laser earns its cost.
| Consideration | Laser welding | Resistance spot welding |
|---|---|---|
| Heat reaching the cell | Confined to a fused zone a fraction of a millimetre wide | Current passes through the cell itself, so heat spreads |
| Pure nickel at full thickness | Unaffected by the material's low resistance | Harder as thickness and purity rise |
| Access | Single-sided; the beam needs line of sight only | Needs electrode access to both sides of the joint |
| Nickel to copper | Practical, with the joint designed for it | Difficult — copper conducts the current away |
| Consumables | None; nothing wears against the work | Electrode tips dress and wear, and drift with them |
| Best suited to | Thicker pure nickel, dissimilar metals, tight or one-sided geometry | Thin plated strip in open, repetitive layouts |
Why Choose Aurico Alloys LLP for Laser Welding?
We are a nickel stockist first, and the welding exists because our customers were buying strip from us and joining it somewhere else. Bringing the two together removes the argument that follows a failed joint: the material, the cut and the weld are all ours to answer for. Busbars can be slit, laser cut or stamped to your layout and welded in the same pass through the shop.
For a pack that is still being designed, that also means the material choice and the joint can be settled together rather than one being forced by the other.
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Conclusion
Every pack decision eventually meets the same wall: the strip that performs best in service is the strip that is hardest to attach. Laser welding removes that trade-off, so the material can be chosen for the pack rather than for the welder. Tell us the cell, the layout and the current the joint has to carry, and we will quote the nickel and the weld as one job.