Why nickel for joining lithium cells?

softdown

While we are it, it does seem like nickel plated iron may be the norm. The electrical conductivity of iron and nickel are fairly similar. Nickel is 1.43 x 10 to the 7th.  Iron is 1.00 x 10 to the 7th.

Then we have "stud" copper which is 5.96 x 10 to the 7th. Why not copper plating for joining lithium cells? Or aluminum? Or lead? All more conductive than nickel and iron. 

Pretty sure spot welding works on other conductive materials. Why do they use nickel/nickel plated iron for joining lithium cells?

BB.

Nickel is relatively cheap and plates to many different metals and surfaces--And can provide a base layer for other plating materials on top.

It is also relatively corrosion resistant.

Here is an 80 page booklet on Nickel plating:

https://www.nickelinstitute.org/media/2323/nph_141015.pdf

-Bill

Dave Angelini

Nickel is also used in the cell of the most common battery type for electric vehicles. NMC lithium ala Tesla and LG. It also can thermal run away and there still to this day is no way to stop it.

"There is no method yet for stopping a thermal runaway event in a BESS installation, according to Swan. "Industry can sometimes get ahead of themselves," he said."  Our friends in Arizona know all about it.

https://www.utilitydive.com/news/lg-chem-refutes-alleged-cause-of-aps-battery-storage-facility-explosion/582740/?utm_source=Sailthru&utm_medium=email&utm_campaign=Issue:%202020-08-04%20Utility%20Dive%20Newsletter%20%5Bissue:28867%5D&utm_term=Utility%20Dive

softdown

BB. said:

Nickel is relatively cheap and plates to many different metals and surfaces--And can provide a base layer for other plating materials on top.

It is also relatively corrosion resistant.

Here is an 80 page booklet on Nickel plating:

https://www.nickelinstitute.org/media/2323/nph_141015.pdf

-Bill

Currently costs more than double what copper costs. Copper "appears" roughly 4 times more conductive if I read things right. 

Perhaps almost all of it is simply nickel plated iron. That would be super cheap. Plating is cheap. Even gold plating is surprisingly cheap. They can plate down to a micron or so. 

mike95490

Copper oxidizes too fast, and is a poor spot weld metal. 

softdown

mike95490 said:

Copper oxidizes too fast, and is a poor spot weld metal. 

Sure - then how about aluminum or lead?  Nickel is pretty darned expensive.  I suspect nickel plated iron and we know that iron is good for spot welding. Though perhaps half of the nickel strips advertise themselves as 99.6% nickel. So why are they always magnetic if pure nickel? Something seems off. 

Dave Angelini

You got the part about nickel in the cell, right? NMC

softdown

Yes - electric cars use it in their battery chemistry. Along with expensive cobalt. They are high performance batteries. But certainly not to be used indoors for solar. I don't think the more common Li - ion, laptop battery type, battery uses it to my knowledge anyway. But I'm pretty new to lithium battery chemistry. 

Lithium titanate may some day be practical for solar. Some day. Handles freezing weather very well. Very safe. Very expensive. Inefficient when discharging though. Big and heavy - almost seems like a LA hybrid in its characteristics. 

Dave Angelini

Actually NMC can be listed for indoors. As long as it complies with UL 1973 or UL 9540 it will meet NEC requirements. It still must be listed for indoor and most would not consider a garage indoor or conditioned space. There are many thousands in California by LG with Solar Edge inverters grid tied.

Many of the LFP batteries meet this at cell level but they are not listed as a battery system.

I can't use them for my clients because I could be sued. My clients would probably have their fire insurance denied in a claim for this reason. It is a fine thing to build a lithium battery system as long as your eyes are open to what you are doing.

I use LFP that are listed as a battery system. About 4 makes now in the US. If they do not sell it in the store here you should beware and research the company.