Supercapacitors ---- Commercial Products vs. University Lab Research

Supercapacitors ---- Commercial Products vs. University Lab Research

First of all, I'm very glad to have a chance to share my concerns and queries in a FORUM of Tesla Motors. I'm an armature researcher in Supercapacitor field, please help me to understand the field in a better way, thanks to all.

Now coming straight to my question:

While supercapacitor companies like Maxwell, Nanotunues are suffering to achieve an energy density higher than 20 Wh/kg,
there are many reports from several university labs worldwide , who reported values in a range 40 to almost 100 wh/kg.

My concern is, in which aspects these university results are not yet ready to be adopted by these frontier companies?
Are they not reproducible? or their measurement techniques are not reliable ? or there are other factors too? or these results are already under consideration and we have to wait for the near future time?

Or, are these research are those, based on what Nanotunes projects an energy density of 200 Wh/kg bby 2014?

Brian H | 05. Oktober 2012

Volume? 200 Wh/per cubic mile of aerogel (1 kg)?

AltenrG | 05. Oktober 2012

Dear Brian,
I'm correct with the unit, data is expressed with respect to the mass of active materials , which are being used to store the charges.

Brian H | 05. Oktober 2012

Yes, I know. Just teasing you with the volume dimensions; caps are BIG, not compatible with personal vehicles.

Timo | 06. Oktober 2012

20Wh/kg is still low for cars. Current Panasonic couple of years old 3.1Ah battery has specific energy of 242Wh/kg and there are techs coming that give more than twice that in near future. Labs show energy densities beyond 1000Wh/kg.

Capacitors just don't have the energy density to compete with batteries. They are good in environments where you need to have huge power density and cycle retention (no degradation in capacitors). IOW hybrids. Maybe.

AltenrG | 06. Oktober 2012

Thanks everybody for replying...

Yes,20 Wh/kg is very low,can you please let me know what is the maximum volumetric energy density for supercapacitors(?? Wh/L)?

"Capacitors just don't have the energy density to compete with batteries", -- Timo

Yes, they don't have till now, I also doubt if they can acheive ever...
What is the main reason behind this ? Is this because of non-faradaic charge storage capacity will be always outperformed by faradaic charge storage?

@Brian: Yes, presently they can not be fitted inside the car dimension, but if they can acheive 200 wh/kg, may be there is a chance, I'm not sure about the volume, because that will be determined by the material only.

Brian H | 06. Oktober 2012

Supercap buffers between battery and motor would seem to have a role.

Brian H | 06. Oktober 2012

Here is an interesting Chinese study (pdf): comparing supercap and faradic battery function.

Be warned, it is somewhat tricky to follow because of the Chinese-like grammar: random use of singulars and plurals, and use or non-use of articles (a, the). As usual, this increases the further you get into the piece. ;)

Brian H | 06. Oktober 2012

"On the other hands" (sic) it's not too bad. Basically a study of the mass discrepancy between heavy anode and light cathode in an optimum supercap design effort.

AltenrG | 06. Oktober 2012

Thanks Brian for the article.... :)

AltenrG | 06. Oktober 2012

Hello Brian, I read the article, which gives a nice explanation for the discrepancy between theoretical and practical potential window for a symmetric supetcapacitor, it also emphasizes on surface functinal groups and their pseudo capacitive contributions to the specific capacitance of a carbon material. Obtaining a purest ( as much as possible) carbon material and adjusting anode and carhode mass ( according to the ion adsorption nature, so that both electrodes have equal charge storage) , may be the key to optimize the double layer performance.
Actually I'm still looking for some other reference, which may explain why Faradic charge stirage is better in term of total energy? I feel the reason is all about inherent energy exchange in a chemical reaction, and this is much larger than a simple electrostatic interaction can. I'm not sure, If I'm correct with my logic, it will be a great help if you can provide another reference for this point or you can si
ply explain to help me understand better.. thanks... :)

Brian H | 06. Oktober 2012

Sorry, don't have one handy. I always understood that molecules could locally retain unbalanced charges better than a surface or conductor, since a static charge always occupies only the surface (as in a Faraday cage or wire). Every molecule has its own "surface".

AltenrG | 07. Oktober 2012

Thanks Brian, I got my answer... :)