Nickle versus aluminium versus copper for welding lithium battery cells

Dear all,

I would like to weld 2 lithium battery cells together using spot welder. I understand that it's common using nickle tab on this purpose. The nickle tab dimension is about 0.5cm x 3cm.

My question is: can I replace nickle with aluminium or copper or other material since nickle cost me alot and it's hard to find them here? My concern if I don't use nickle, they will have lower performance and/or won't have a longer life. Please advice.

Many thanks!

Andre

Reply to
Andre
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Unitek has some application notes about spot welding battery tabs. They say that the materials typically used for tabs are either nickel or nickel-plated steel, .005" thick. Battery caps are usually nickel-plated steel. I'm no expert, but I suspect it will be difficult or impossible to get a good weld using copper or aluminum tabs.

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-- Steve
Reply to
Steve Dunbar

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Steve, many thanks for your reply. I do some search on the web for 2 weeks and so far, I have to admit that _nobody_ weld 2 battery cells together with copper or aluminium. Also can't find that anybody ever ask this question, both on the mailinglist and newsgroup.

I asked once with a lithium battery cells salesgirl in China (and she ask her engineer), the answer is: nickle should be used rather than aluminium or copper, since nikcle's _impedance_ is lower (or higher?) compared with copper or aluminium, that will effect the battery pack performance. Anybody can confirm about this? Again, many thanks!

Andre

Reply to
Andre

Dear John, many thanks for your reply. Yes, I found nickle strip in every laptops battery pack I opened. What I try to do is un-weld the battery cells and replace it with a brand-new battery cells, and then weld the brand-new cells together. Sometime, in the process of un-welding the old cells, the nickle strip damage and have to replaced. Since I do this works many time, I need many nickle strip that cost me alot. So I try to find other solution that cost me cheaper. Andre

Reply to
Andre

Greetings Andre, The biggest problem with copper or aluminum compared with nickel is the very low resistance of the copper and aluminum. The resistance is virtually the same as the spot welder electrodes. So it is hard to get the spot to weld before the electrodes get too hot. The higher resistance of the nickel means it will get hot and melt well before the copper electrodes. Aluminum has another problem besides the low resistance and that is the thin oxide coating that forms on aluminum almost instantly when a freshly cleaned surface is exposed to air. This oxide coating makes it hard for other metals to stick to the aluminum. When aluminum is welded by either the arc or flame process the oxide coating is removed. When tig welded the weld is protected from oxidation by inert gas and when gas welded with a flame flux is used to remove the oxide coating and prevent forther oxidation. Cheers, Eric R Snow

Reply to
Eric R Snow

It will not be easy to choose what tab you use. The tabs are usually already on the cells. It would be very difficult to weld a tab on a complete cell.

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John G

Wot's Your Real Problem?
Reply to
John G

Dear Eric,

Many thanks for your reply! This is a very good explanation about copper and aluminium! I will try copper with my spot welder, if it's can't weld good with the welder, I have no choice to use nickle :(

Thanks again, Eric!

Andre

Eric R Snow wrote:

Reply to
Andre

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