Is EDC and EDS family ESR really in ohm unit?

Nice catch - my apologies, I didn't even notice the unit switcheroo. I had assumed they all used the same units based on reading the radial datasheets first that I didn't see that they said ohms! CDE are correct.

If you look at my measurements, I would say it is correct as I was measuring multiple ohms for all coin cells:

 What’s Super about Supercapacitors? – Part 3: Measuring Capacitance & ESR 

As a result, what I thought was out of spec is actually in-spec! A nice finding indeed.

- Gough

Nice. Thanks for clarification. Looks like EDS and EDC has significantly different structure internally in comparison to radial supercaps.

Yes, it is likely they are something more akin to a battery in a paste composition perhaps or maybe layers, as there isn't space for the "scroll" type structures which increase surface area and reduce ESR as a result.

That being said, I haven't opened up a coin-type one yet, but I might do now that you mention it ...

- Gough

Yes, it is likely they are something more akin to a battery in a paste composition perhaps or maybe layers, as there isn't space for the "scroll" type structures which increase surface area and reduce ESR as a result.

That being said, I haven't opened up a coin-type one yet, but I might do now that you mention it ...

- Gough

thanks, but you do not need to destroy it just because of me. I am not chemistry expert, so I still will not understand it very much.

Gough Lui said:

I haven't opened up a coin-type one yet, but I might do now that you mention it ...

That would be quite interesting. 

The challenge is to learn, and that's one way to do so. I've already destroyed many as part of my learning journey so that's all good. Might do it sometime in the next couple of days ... it'll probably make its way to my final blog too ...

- Gough

There's some crazily-low ESR EDLC types in a flat format. TDK has some: 

https://product.tdk.com/en/search/capacitor/edlc/edlc/catalog

For a project a while back I obtained one which is claimed 300 milliohm and is thinner than a PCB (quite handy for hiding, for "dying gasp" scenarios if someone disconnects a battery!). However the Cornell Dubilier ones look a lot more robust, and I wonder if they maybe prioritised other features over ESR for that particular range. I've no idea though.

If you do open one up, please do so with care. The electrolytes used in coin cells tend to be very acidic. (Some vendors literally use a form of sulfuric acid.)

I can't speak to the CDE construction, but I assume they use similar techniques to other vendors who make similar cells.

Thanks for the tip - I did go through a few MSDSes in this blog but none of them seemed applicable to coin-cell types. Yes, protection is required as the compounds are known irritants, but quantities are relatively small.

I suspect their design are based on being equivalents or replacements for the discontinued and rather popular Matsushita/Panasonic GoldCaps. Based on their brochure (https://industrial.panasonic.com/content/data/CP/PDF/Electric_Double/EDLC_TechnicalGuide_e.pdf), I'm expecting to find this:

- Gough

On my first read of that datasheet, I noticed the word "electrolyte" was used without any chemical names. Then I saw on page 2 they say the electrolyte used in Gold Capacitors is non-water soluble. Which, to me, says it is not sulfuric acid.

However, if an EDLC is using an "aqueous electrolyte," then I would think otherwise.

Supercaps use an organic electrolyte called Acetonitile (methyl cyanide) which is considered a hazardous substance when it comes time for disposal.

So be careful - as I'm sure you will be ....

MSDS:

https://www.sigmaaldrich.com/CA/en/sds/sial/271004

There is not a "one electrolyte for all" when it comes to EDLCs. (Or any electrolytic capacitors, for that matter.)

Very large can cells typically Acetonitrile.

Smaller cylindrical cells, the ones that look like radial aluminum electrolytic capacitors, typically use Propylene Carbonate (PC).

(In some cases, both styles use the opposites.)

And coin cells usually use some form of acid.

I am guessing that you want to keep them away from children who might swallow such things.