Stevei3
Posts: 364
Joined: Mon Sep 02, 2013 9:02 am
Location: the Netherlands

Re: Battery Chemistry

Mon May 05, 2014 6:08 am

Hi DanS,

afaik, Bosch and/or the Bosch/Samsung colaboration was dropped as battery supplier. It looks like Samsung is the sole battery supplier, see for instance this link on Reuters: http://www.reuters.com/article/2014/01/ ... YZ20140123

I think Tom's blog posting about the battery states Samsung as supplier as well. But do correct me if I'm wrong.

Regards, Steven

ultraturtle
Posts: 439
Joined: Sun Dec 30, 2012 11:17 am
Location: Peachtree City, Georgia USA

Re: Battery Chemistry

Mon May 05, 2014 8:18 am

Dan5 wrote:That is why I used other EVs and packs as comparisons.

Dan, thanks for all of the information. I learned a lot attempting to track down sources. Understandably, manufacturers are very tight-lipped about battery chemistry, and all we really find is a tremendous amount of unsourced conjecture from inquisitive folks like us.

I don't agree that one can infer the comparative energy density of a battery cell technology based on the energy density of a battery pack:

    - First there are differences of scale. The BMW i3 battery pack has roughly 1/4 the capacity of the 85kWh Tesla Model S, so considering some fixed components that do not scale, it is highly probable that a pack of 1/4 identical cells will be more than 1/4 the weight
    - There is volumetric efficiency. A 1' x 1' x 1' empty cardboard box weighs more than 1/4 the weight of a 1.6' x 1.6' x 1.6' empty cardboard box, but has 1/4 the volume.
    - There are varying design objectives for a given battery pack. For instance, to make cooling highly efficient, and the battery pack less explody, BMW chose to use a freon refrigerant cooling system in the pack, which surely must add some weight. (see http://darrenortiz.com/website_pdfs/BMWi3PG.pdf)

Back to the original question - does anyone have a source indicating the i3's battery chemistry? I can only find two (thanks, Buskraut!), and neither is from a manufacturer. They both point to NMC:


I have been unable to find any source that suggests otherwise.

Dan5
Posts: 5
Joined: Sun May 04, 2014 1:41 pm

Re: Battery Chemistry

Mon May 05, 2014 4:30 pm

ultraturtle wrote:
Dan5 wrote:That is why I used other EVs and packs as comparisons.

Dan, thanks for all of the information. I learned a lot attempting to track down sources. Understandably, manufacturers are very tight-lipped about battery chemistry, and all we really find is a tremendous amount of unsourced conjecture from inquisitive folks like us.

I don't agree that one can infer the comparative energy density of a battery cell technology based on the energy density of a battery pack:

    - First there are differences of scale. The BMW i3 battery pack has roughly 1/4 the capacity of the 85kWh Tesla Model S, so considering some fixed components that do not scale, it is highly probable that a pack of 1/4 identical cells will be more than 1/4 the weight
    - There is volumetric efficiency. A 1' x 1' x 1' empty cardboard box weighs more than 1/4 the weight of a 1.6' x 1.6' x 1.6' empty cardboard box, but has 1/4 the volume.
    - There are varying design objectives for a given battery pack. For instance, to make cooling highly efficient, and the battery pack less explody, BMW chose to use a freon refrigerant cooling system in the pack, which surely must add some weight. (see http://darrenortiz.com/website_pdfs/BMWi3PG.pdf)

Back to the original question - does anyone have a source indicating the i3's battery chemistry? I can only find two (thanks, Buskraut!), and neither is from a manufacturer. They both point to NMC:


I have been unable to find any source that suggests otherwise.


Actually that was the reason I used the Model S as a comparable vehicle, it also has a water cooling system to keep the batteries cool. I think Tesla and BMW are both capable of designing a cooling system that is lightweight, but still provides adequate cooling.

The Tesla is a very conservative number and one would assume that the "plate design" that BMW uses actually decreases the weight.

Remember Tesla is using a bunch of these cells called 18650's (essentially the orientation of the cells you find in laptops) and as such have about 11% of the weight that is coverings.

The only odd balls would be the leaf- air cooled and the MiEV.

I think we did narrow it down, Altair is not the supplier, neither is Toshiba- means it is not lithium titanate
A123 is not the supplier- means it is not iron phosphate
Panasonic is not the supplier that means it is not NCA
The criteria for cobalt oxide does not fit.

The Volt is like 83 Whr/kg and has liquid cooling (We all know about the crash test where the coolant leaked 2 weeks later and short circuited the battery) and that is manganese oxide

So it's 12% more than manganese oxide (pure) battery, but not quite as much as a pure NCM battery.
I found this paper, this may be something that they did- doping with Cobalt
http://www.electrochem.org/dl/ma/206/pdfs/0416.pdf

Makes sense, Samsung works with NCM and NCA
Also I narrowed down one of the authors.
Atsuo Yamada is involved in the Samsung group
http://www.researchgate.net/publication ... _electrode

If only we could link him further... :)

ultraturtle
Posts: 439
Joined: Sun Dec 30, 2012 11:17 am
Location: Peachtree City, Georgia USA

Re: Battery Chemistry

Tue May 06, 2014 7:21 am

Dan,

Thanks for the additional sources.

According to page 17 of this document - http://darrenortiz.com/website_pdfs/BMWi3PG.pdf, the i3 utilizes 8 modules weighing 25 kg each, which would make the pack level energy density 108 kWh/kg. While I still do not generally agree that pack level energy densities are useful for sleuthing cell chemistry, I think being in the same order of magnitude might be of some use. Volumetric efficiency alone might account for differences, as the 85 kWh Tesla Model S module has 31.5 times the capacity of a single 2.7 kWh i3 module.

I was unable to locate a source for the Tesla Model S battery pack weight. Could you steer me in the right direction?

Dan5
Posts: 5
Joined: Sun May 04, 2014 1:41 pm

Re: Battery Chemistry

Tue May 06, 2014 4:08 pm

ultraturtle

Here's the car and driver article
http://www.caranddriver.com/reviews/201 ... est-review

Graph with the battery pack comparison with a leaf.
1323 lbs/601 kg for 85 kwhr pack ~ 140 Whr/kg

Plus when that article Dec 2012 was written only 85 kwhr packs were being delivered

Now if you take out the modules themselves and weight out the batteries
There are around 7104 batteries each weighing 45 grams = 320 kg, or roughly half is the cells, other half is controllers, fluid, dividers, etc.
http://lygte-info.dk/review/batteries20 ... %20UK.html

16 modules * 6 groups * 74 cells per group = 7104 cells

You can also back calculate, easy since they are 18650s
85000 whr / (3.4 Ah *3.6 V) = ~6950 cells
Or if you use 3.1 Ah (older cells) you get ~ 7600 cells

EVMan
Posts: 245
Joined: Sat Feb 25, 2017 4:31 pm
Location: USA, CA

Re: Battery Chemistry

Mon Nov 05, 2018 11:33 am

As the i3 batteries are changing , from 94h to 120h, the nickel content keeps increasing and cobalt and other content for stability keeps reducing. NMC111, to NMW622 to may be NMC 811
While of course, the total capacity increases, what is it coming against ? What are the Cons ?
I guess reduced stability means , reduce temperature operating range, reduced safety and what else ?
Will it also reduce battery c rate ? The books says, the c rates also in increase always, but at least for the Bolt with NMC622 the c rate looks less.
The battery cycle rates will also reduce, but may balance out with less cycles needed.

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2016 22KWH Rex ( Lease to Return ) ~ Model 3 Dual Motor, Long Range ( Wait-listed )
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MKH
Posts: 21
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Battery Chemistry

Thu Nov 08, 2018 10:49 am

Mark H.
2015 i3 Rex, Capparis White, Tera World, Tech + Driver + Parking, Harman Kardon, 20 inch wheels

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