Battery Chemistry

Hi all,
I was just wondering what the battery chemistry was in the Model S. I know that it is different for the 40kwh/60kwh and 85kwh battery packs. Just wondering so I can do some research on the reliability of the Cell chemistries. I'm pretty sure it's been posted in the forum before but I can't find it.

Good digging Njck. Elon was pretty explicit about asserting that they pushed Panasonic to optimize cells for their purposes.

So one could imagine modified electrode structures or electrolyte doping for their automotive objectives.

My guess is that this would be in the form of Elon guiding Panasonic engineers to new strategies and specs. If TM had patents in this area, they might command exclusivity, but my guess is that it might have instead been part of the package of consideration for Matsushita's investment.

Other sources, such as the Stanford talk and paper on the Tesla batteries suggest that part of the modification is battery management/manage to prevent thermal runaway.

Li-Tec battery is another leader that makes 3.2 Ah batteries better than 3.1

nickjhowe, you rock. Even if it's not the optimized cell I now have an idea for how the cells degrade with cycle number in lab conditions. Optimally (and optimistically) it looks like it lost 500mAh capacity over 300 cycles (16.7% loss). or 99.94% cycle efficiency. The trend doesn't exactly appear linear (linear wouldn't make sense regardless), kind of like an upside down ln() function. I tried to make somethings fit in excel but failed. Anyways with a linear trend you can expect to see full cell degredation after 1800 cycles?

Hi All,

I vaguely recall reading some time ago that Tesla's pack have redundancy "design in" with bypass of non performing cells. They are the only ones in the EV industry who is able to balance 8,000+ cells. There has never been a report of packs fire from Tesla.

There is much talk about active balancing concepts and using smart chips to balance individual cells voltage during cycling. Could someone out there shed some light as to how Tesla manage to monitor and balance 8,000 + individual cells. How the bypass of non performing cells is carried out?


Tesla and Boeing use the most unstable and flammable chemistry. Lithium Cobalt is used due it's high energy density. Check out the link:‎

Evnut, that's not accurate. I very recently watched Elon speaking about the battery, he listed the elements Lithium, Cobalt, Nikel and Aluminum. After a very quick search I learned from an MSDS the chemistry was the following:

Anode: Carbon (most likely including something like carbon nano fibers to help durability)

Electrolyte: 1.2M LiPF6 in some mix of Ethylene carbonate, Propylene carbonate, Di-methyl carbonate, Diethyl carbonate.

Cathode: LiCoNiAlO2.

Thanks everyone for the effort. Seems I was the one who solved it!

It is likely true, that the chemistry is a bit altered, albeit not necessarily. Companies sometimes say they use customized blends of
components and raw materials, to throw off competition and to
provide a more upscale feel to the product.

With boeing, it isn't as simple. It depends on what you view
as a battery. Cells, BMS and charger or just cells, etc.

I think BMS mistreats the cells badly in those incidents.
Those cells aren't the kind that tolerate faults.

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