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Nickle versus aluminium versus copper for welding lithium battery cells

Discussion in 'Electronic Basics' started by Andre, Jan 16, 2005.

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  1. Andre

    Andre Guest

    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 <>
     
  2. Steve Dunbar

    Steve Dunbar Guest


    Unitek <http://www.unitekequipment.com> 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.
     
  3. John G

    John G Guest

    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.
     
  4. Andre

    Andre Guest

    tabs.

    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 <>
     
  5. Andre

    Andre Guest

    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 <>
     
  6. Eric R Snow

    Eric R Snow Guest

    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
     
  7. Andre

    Andre Guest

    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 <>
     
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