Talk:Electric double-layer capacitor

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Comment[edit]

The second two paragraphs need rewording. They're not at all clear. We need an expert to fix them.

Ultracapacitors[edit]

Does anybody know what is the difference between supercapacitors and ultracapacitors? --Shaddack 20:50, 22 November 2005 (UTC)


As far as i know ultracapacitors and supercapacitors are the same thing, just different words, so the articles probably should be combined.


I realize that I'm very late to this party... the comment between me and Shaddack is unsigned.

Supercapacitor is(or was) a tradename for an ultracpacitor, much the same as kleenex for facial tissue or xerox for photocopy. I believe the original tradename was owned by NEC, but I'm not about to research that. I'm not sure who owns the tradename now or if it is enforced, below are some links to some major manufactures and what they call them. It appears the EDLC, supercap, & ultracap are interchangeable.

avx product page - supercaps maxwell product page - ultracaps CDE product page - ultracaps kemet product page - supercaps murata products - supercaps illinois capacitor - supercap/ELDC

I would suggest that articles for supercap, ELDC, or ultracap should put you to the same article.

Ratherbeskiing (talk) 18:10, 18 March 2016 (UTC)

Hi Ratherbeskiing, please have a look at the paragraph "#Change in understanding: From Electric double-layer capacitor to Supercapacitor below the discussion page. --Elcap (talk) 09:05, 20 March 2016 (UTC)

Energy density[edit]

Does anyone have any data to back up the claim that Cooper Electronics makes super capacitors with an energy desity of 325 kJ/kg? It dosen't say on thier webpage or any where else on the web as far as I can tell. Compared to other supercapacitor manufacturers it seems outragously high. cc 24.137.78.34 23:37, 8 February 2006 (UTC)

ACI has a produce called Energel(tm) which is an aerogel based capacitor that takes advantage of the aerogel's extremely light weight and extremely high impedance to make capacitors of very high performance.

http://www.allbusiness.com/transportation/motor-vehicle-manufacturing/877179-1.html?yahss=114-2974554-877179

This is an announcement of an ultracapacitor containing 325 kJ/kg which is better than a lithium ion battery. It also produces 20 kW/kg - far superior to any battery. Awesome performance! Cost is not mentioned. But given the low volumes of material, with the appropriate investment in tooling, costs could be very inexpensive indeed. You'd still need 370 kg to equal 1 gallon of gas though! (325 kJ/kg x 370 kg = 120MJ) But using an electric motor instead of an internal combustion engine would increase effectiveness by 3 to 7 times, since a thermal engine is notoriously inefficient when compared to an electric engine. So, perhaps 50 kg (110 lbs) of ultracapacitors might do the job of 1 gallon of gas.

http://en.wikipedia.org/wiki/Energy_density

The energy density of normal capacitors is around 1 kJ/kg, hence the name super- and ultra-.

Ultracapacitors have energy densities well above supercapacitors. Ultracapcitors are potential battery replacements since they store energy in the same range as batteries - greater than 100 kJ is higher than lead acid. Ultracpacitors use carbon aerogel films that are treated with a Ruthenium Oxide vapor on either surface to produce these extraordinarily high energy densities.

http://www.che.sc.edu/faculty/white/2001StudiesonActivatedCarbonLoadedRamaniHaranWhitePopov.pdf

The high energy densities come about due to the very low masses of the aerogel and their very high electrical impedence.

Supercapacitors contain about 20 kJ/kg and are manufactured more conventionally.

All capacitors store a charge Q at a particular voltage - this is called capacitance measured in farads

http://en.wikipedia.org/wiki/Capacitance

A coulomb is approximately 6.24e18 electrons. A 100 farad capacitor would store 100 coulombs at 1 volt. 10,000 coulombs at 100 volts. All capacitors have a breakdown voltage and the breakdown voltage for ultracapacitors based on aerogel dielectric is extremely high.

The energy stored in a capacitor is given by

W = 1/2 * C * V^2

where

W is the energy measured in joules C is the capacitance, measured in farads V is the voltage measured in volts

To get energy per unit mass divide by mass.

Because aerogels are so light weight (the lightests are 1.0 mg/cc (less than air which is 1.2 mg/cc)) and have such a high electrical impedence - they naturally form very high performing capacitors.

This leads to another point. While 50 kg of ultracpacitors might do the same duty at a gallon of gasoline - at 1.0 milligram per cubic centimeter - or even 10 milligrams per cubic centimeter - with their RuO coatings - you'd need 5000 liters of ultracapacitors to store the energy equivalent of 1 gallon of gasoline.

Where would the volume be stored? Well, one highly speculative solution would be in the car's body. If the car's body and basic structure were made of structural aerogel material that did double duty as an aerogel capacitor - it might be stored there.

So it might be feasible to make ultralight vehicles about 1/4 the weight of the Venture One - that got say 250 mpg - equivalent - which would store 120 MJ and at 20 kW charge/discharge rate would take less than 2 hours to charge and discharge.

http://en.wikipedia.org/wiki/VentureOne


Ult —Preceding unsigned comment added by 24.31.177.20 (talk) 23:49, August 24, 2007 (UTC)


I don't see it on their site, but this article may be the source for our data: [1] -Will Beback 23:45, 8 February 2006 (UTC)

The highest energy density capacitor manufactured by Cooper Electronics appears to be the B1840-2R5506, supplying 50F at 2.5V, and weighing 14.7 grams. So, I estimate a total energy capacity of (1/2) * 50F * (2.5V)^2 = 156.25J, or a power density of 10.6 kJ/kg. Given this enormous discrepancy (325kJ/kg doesn't square up with any other source on supercapacitors I've seen), I think the number needs to be corrected.

My figures are from: http://www.cooperet.com/products/products.cfm?page=supercapacitors

Alexey

I do not think that the actual claim is that Cooper Electronics makes such a super capacitor. If you just take the numbers provided in the article itself or in its source referenced above, then the 104 F/g translate directly into the disputed value of 325 kJ/kg (0.5 * 104 F/g * (2.5V)^2 = 325 J/g!). The real question is, whether the 104 F/g device provides 2.5V. Does anyone know the source of the 104F /g and could provide the corresponding voltage value?

Some additional references I could find for the actual numbers in the article, e.g. the following paragraph from a press release [2]: The extremely high electrochemical surface area of ACI's ENERGel(TM) carbon aerogel enables very high rates of charge and discharge. Capacitances of more than 104 F/g and energy densities of more than 325 kJ/kg have been demonstrated with carbon aerogels ultracapacitors. Additionally, power densities of up to 20 kW/kg have been achieved. This is orders of magnitude higher than what conventional capacitors offer. ACI believes that its ENERGel(TM) carbon aerogel is a superior option for applications such as specialized electrodes.

Another one is [3]. There you can find (follow the links Carbons/Electrode Carbons/ultracapacitors), values of 123 F/g for this type of material, which would result in even higher numbers. Those numbers certainly show a potential for these kind of energy densities, rather than making a claim that they are already available in an existing commercial device. Maybe someone with the necessary expertise (I do not think I am) feels like being the right person to change the wording as to make the article clearer in that respect.

Manfred

Since our name is mentioned, I feel obligated to reply. Our press release references these number from this very web site. So, if there is correction required, it is important that it be corrected. However, in defence of carbon aerogel, Alexey, the weight of capacitance cited must be the weight of carbon, not the whole capacitor. The weight of capacitor can be more than ten times the weight of carbon aerogel depending on the system. Specifically, Cooper's carbon aerogel is the ground powder coated on to aluminium current collector, and bound spiral. There are other components, electrolyte and outside shell probably weighs the most. All these weighs more than carbon itselfby the way it is designed. You cannot compare system weight and electrode weight. Ground carbon aerogel with binder compromises its packing density and conductivity.

The number I believe must have been calculated by using monolithic carbon aerogel electrode. It can have much different packing density. Additionally, carbon aerogel with different porosity exhibit different properties. While the surface area can be constant per weight of carbon, it can be much less per volume when porosity is very high.

ACI

I'll delete the disputed info from the article and suggest to not include it again, until it get published by a reliable secondary source, e.g. an IEEE journal. --Pjacobi 13:38, 31 August 2006 (UTC)

Pmurray bigpond.com 02:56, 25 May 2006 (UTC)[edit]

So the article could be corrected by using the higher figure, and quoting it as "kJ/kg (of electrolyte)". I suppose it depends on whether a reader is interested in the capacitance of carbon aerogel per se, or of the current state of the art with respect to practical applications. Pmurray bigpond.com 02:56, 25 May 2006 (UTC)

No, no, not "kJ/kg (of electrolyte)"! ACI said that it is the electrolyte and other materials in the capacitor that add so much mass. The correction would be "kJ/kg (of electrode material)". JDHeinzmann (talk) 15:08, 19 February 2008 (UTC)

Superconduction?[edit]

On another note, what is this about using ceramics for their superconducting properties? what temperatures do people plan on using these devices at? If anyone wants to back this up, please throw in a reference other than the one at the bottom which the first part of this page appears to be an 'adaptation' of. Perhaps this line should read "Research is being conducted into the viability of superconducting ceramics as a replacement for CNTs in certain low temp. applications", however ceramics such as NiO are being investigated as well.

  • I am confident that the reference to use of superconducting properties is mistaken, and have removed it. Harold f 20:04, 8 March 2006 (UTC)

Electrochemical Capacitors[edit]

Supercapacitors or ultracapacitors are the same name for the electrochemical capacitors. These capacitors are different from conventional capacitors. These capacitors have a higher energy-density than that of conventional capacitors and higher power-density than that of batteries.

Electrochemical capacitors are based on two mechanisms. 1) Double layer and 2) Pseudocapacitance

Ashish Varade (Material Research Centre, IISc) (220.227.207.12)

Perhaps the article should be moved to "electrochemical capacitor", with "supercapacitor" and "ultracapacitor" listed as alternative names. -- Kjkolb 12:53, 6 January 2006 (UTC

Capacity[edit]

Digikey is currently offering what I believe to be a single-cell supercapacitor rated to 5000F. You may want to change the bit at the bottom about the max being 2600F.

Uses[edit]

I am considering adding a Uses section. The article mentions the potential use in electric vehicles, robots, and memory backup for computers. Another use is in rechargeable electronic toys such as RC cars. The uses seem to be scattered throughout the page. Should we consolidate them? --24.16.148.75 23:34, 30 June 2006 (UTC)

Another possible candidate ?!

Manufactures -- EEStor Removed[edit]

For now the article lacks a breakdown of the most important manufactures. Instead it did have an entire chapter on the dubious claims of EEStor. I've removed that. --Pjacobi 20:52, 28 July 2006 (UTC)

Why are the claims of EEStor dubious? I agree it is frustrating not to be able to know what is happening at that company -- but how can you say they are dubious? They are too good to be true, or what? It seems wrong to silence them.

EEStor is quite dubious, as they have not actually released any results, nor have the results been independently verified. They may or may not have accomplished what their patent [4] claims, but I have read far too much about past "breakthroughs" that never came to fruition. Anyway, as a recent article in the Toronto Star [5] makes clear, we aren't silencing them, they are silencing themselves, for whatever reason. The information about EEStor comes almost exclusively from this patent, not anything anyone has seen in person. That said, I hope, as much as anyone, that the claims turn out to be true. 21 August 2006

  • I added an External Link to an EEStor profile on Business 2.0 / CNN.com. --AStanhope 16:19, 26 September 2006 (UTC)
  • I added a sub-section on EEStor not having read this discussion. I agree that this is an unproven development, but this is a topic that can be expected to generate a lot of interest in current development work. --C J Cowie 20:58, 1 October 2006 (UTC)
Sorry to revert your work, but the essential prerequisite for mentioning in Wikipedia is verifiability by means of reliable third party sources. Neither press release nor patent applications will do. We don't need to speculate or rush, Wikipedia is not a news portal. Once the dust has settled, one way or another, we know whether and what to write. --Pjacobi 21:24, 1 October 2006 (UTC)
Is the MIT LEES capacitor considered verified then? The references seem to describe ongoing development work. --C J Cowie 21:31, 1 October 2006 (UTC)
IMO, The MIT work does get a bit hyped. It's one thing to use nano-technology to improve battery efficiency, which requires just a few thin layers of the good stuff. It's another to make a capacitor where the bulk of the material is built from carbon nano-tubes. I put the LEES concept in the wishful thinking category. However, the MIT progress is posted, while EEStor is mute. Anything we say here about EEStor is simply speculation. What we say about the MIT work is verifiable. Smilindog2000 13:29, 14 November 2006 (UTC)

There's an additional problem with including EEStor here: they are not EDLCs. They could be mentioned, just like oranges might be mentioned in the apple article, but only as another fruit, not as a kind of apple. Ccrrccrr (talk) 02:51, 27 November 2008 (UTC)

Glaring omission[edit]

An important characteristic of capacitors is its Capacity per unit of Volume or mass (not sure). This is an essential characteristic for this article. Andries 19:32, 31 August 2006 (UTC)

power / energy units[edit]

I edited the page under disadvantages to read "power" instead of "energy" since the units listed were Wh instead of joules. Someone should fix the chart too. Energy is not measured in Wh and all you are doing is confusing the masses.

William Dryden

Watt hours are energy units, not power. One joule is equal to one watt-second. One watt-hour is equal to 3600 joules. One kilowatt-hour is equal to 3,600,000 joules. Kilowatt-hours are often used for utility billing purposes. --C J Cowie 13:54, 1 October 2006 (UTC)
Sorry William, but you are wrong Energy is measured in Watt-hours. Or, you can measure it in Watt-seconds (Joules). OTOH, power is measured in Watts. Therefore, this:

"High specific power. According to ITS (Institute of Transportation Studies, Davis, California) test results, the specific power of electric double-layer capacitors can exceed 6 kW/kg at 95% efficiency[14]"

Might require some further explanation as to what it means.

Tyrerj (talk) 12:08, 29 September 2010 (UTC)

Alexander Bell[edit]

This article reads as if it's self promotion; now, I have no idea whether Dr Bell edited it, but it needs to be edited to focus less on the person and more on the capacitors Witbrock 15:49, 19 March 2007 (UTC)


Additionally, the article referenced was authored by Aleksandr Belousov not Alexander Bell.

Self-discharge/Leakage[edit]

It's noticable that the described applications of these capacitors all involve fairly short-term energy storage. Is this because the self-discharge rate is high (compared with chemical batteries)? It would be helpful if the article included a discussion of the self-discharge rate. EdDavies 20:01, 27 April 2007 (UTC)

If you look at the features/advantages section and the adjoining graph comparing energy density vs. power density, it's clear that current super caps are better suited to high power vs. high energy role. Based on the article, super caps have about 1/10 the energy density of chemical batteries, but 10 times the power density. What this means is that they are good at short bursts, but the total energy is not so great. Another way to look at it: chemical batteries have a higher internal resistance, but they they can store more energy for a given size. Some rechargable chemical batteries don't have particularly good leakage characteristics either. Madhu 17:52, 30 April 2007 (UTC)

{{Cleanup}}[edit]

This article sadly detoriated to a dumping ground of drive-by-promotion of companies and inidividuals. I've reverted the most recent offender[6], but also the version I've reverted to needs massive cleanup. --Pjacobi 12:45, 25 April 2007 (UTC)

rechargeable batteries as capacitors[edit]

What are the effective equivalent capacitances of various common small rechargeable batteries? What F-V combinations are common for current supercapacitors? What is typical current cost per F-V?-69.87.200.101 18:09, 27 May 2007 (UTC)

Tiny .6F 3V polyacene are common. $1.10 from one source. 5/$1 from another (PAS 920). What is the self-discharge?-69.87.200.101 18:15, 27 May 2007 (UTC)

One Farad changes by one volt in response to one amp-second. Consider a rechargeable AA or AAA NiMH that changes by .5V in response to 1000mA-Hr. That would seem to be equivalent to 1A-2Hr for 1V = 60x60x2 = 7200 Farads. (Batteries are less efficient, returning 80% of charge current if things are working well?)-69.87.204.35 01:37, 28 May 2007 (UTC)

It's not a very reasonable approach to equate batteries and capacitors; the energy storage mechanisms are vastly different, and while the terminal voltage of a capacitor is directly related to the energy stored in it, the terminal voltage of practical batteries is very roughly constant, and doesn't decline significantly till it's nearly discharged. Draw down a capacitor to half it's initial voltage and you've withdrawn 3/4 of its stored energy; discharging a lead-acid battery to half it's intial voltage will send you shopping for a new battery. --Wtshymanski 17:58, 15 June 2007 (UTC)
Well, for purposes of this article, we must thoroughly understand how to compare batteries and capacitors, what the similarities and differences are, practical and theoretical, since the whole point is to use them in similar ways (modular portable energy storage and release).-69.87.199.150 12:24, 14 September 2007 (UTC)

kilofarad range capacitors[edit]

Sadly, "kilofarad range capacitors" are not yet "widely available". Just trying to find anything over about 1F gets quite expensive, and the voltages available are very limited. If you think "kilofarad range capacitors" are indeed widely available, please list right here the best ten sources where we can actually buy them, along with an example size, value and price for each source!-69.87.199.150 12:22, 14 September 2007 (UTC)

Complete detailed specifications on one maker of low-voltage 3 to 5000 Farad is available here:[7] However, there are no prices or any information about where it might be possible to actually buy them.-69.87.199.150 12:51, 14 September 2007 (UTC)

Search digikey.com for "supercapacitor". There you will find a number of capacitors listed in the 1200 F to 5000 F range. At this moment they offer 1700 F @ 2.7 V for $160, 3500 F @ 2.7 V for $210, and 5000 F @ 2.7 V for $255. These are made by NessCap Co Ltd. So they do appear to be available, though I would not say that this is an indication that they are widely available. JDHeinzmann (talk) 15:33, 19 February 2008 (UTC)

Terms[edit]

I have no idea if NessCap is "notable", or their cross-lawsuits with Maxwell over patents and producets, apparently after a failed merger.[8] However, it does seem like the article should explain to us terms like prismatic and non-prismatic, so that we can understand the subject. Also, the terms Electric Double Layer Capacitor and Pseudocapacitor.-69.87.199.150 12:51, 14 September 2007 (UTC)

Formula 1 stuff[edit]

The section on the Forumula 1 stuff is vaguely relevant, no need to include all the rules of an auto race in this article. --Hooperbloob 19:30, 14 October 2007 (UTC)

External links[edit]

To those who disagree with my removal of the external links section: please first read WP:EL. The links were mostly pointing to press releases ("wow, there is a car that has a supercap built into it!") and "informational" websites that were using Wikipedia as an advertisement vehicle. Many of the press releases were actually incorporated into the article as references. The other ones fail the criteria "links normally to be avoided" on WP:EL, more specifically:

  • 4. Links mainly intended to promote a website.
  • 14. Sites that are only indirectly related to the article's subject: the link should be directly related to the subject of the article. A general site that has information about a variety of subjects should usually not be linked to from an article on a more specific subject. Similarly, a website on a specific subject should usually not be linked from an article about a general subject. If a section of a general website is devoted to the subject of the article, and meets the other criteria for linking, then that part of the site could be deep-linked.

Han-Kwang (t) 09:47, 12 November 2007 (UTC)

I think there were some very good external links.. I do agree that there were some not so good. I come here to link out to blogs and other sites. I think it is important to at least have some. I can't imagine removing all the external links sections from Wikipedia. Is that is is going to happen? Thanks. —Preceding unsigned comment added by 216.253.178.230 (talk) 22:06, 12 November 2007 (UTC)
WP:EL#Links normally to be avoided #5: Links to sites that primarily exist to sell products or services. For example, instead of linking to a commercial bookstore site, use the "ISBN" linking format, giving readers an opportunity to search a wide variety of free and non-free book sources. #11: Links to social networking sites (such as MySpace), discussion forums/groups (such as Yahoo! Groups) or USENET. #12: Links to blogs and personal web pages, except those written by a recognized authority. - (), 00:09, 13 November 2007 (UTC)


Grid Energy Storage?[edit]

Anyone know if this could this be scaled up to handle MW (MegaWatts) of power (not sure that's the right unit of measurement here)? I think there are batteries currently in the world that handle this level of power. This link [9] says the world's largest battery (in 2005) can do 40 MW for 7 minutes or 27 MW for 15 minutes. --204.4.131.140 (talk) 10:34, 23 November 2007 (UTC)

Yes. It might be beneficial, since the issue of aging is less present for capacitors than for batteries. But I guess that even with the longer potential lifetime, batteries are still so much cheaper that commercially it would be of little interest for large-scale use.
Another point I can see is the risk associated with this relatively new and complex technology. The "good old" lead-acid batteries can be operated very safely and reliably nowadays (assuming proper maintenance).
LiIon batteries have larger eneryg density, but cannot be easily manintained and may fail early, sometimes catasthrophically (isolator failure), even when used properly. This risk makes such batteries a much less favourable candidate for grid energy torage, obviously! Note that it's apparently possible to build more reliable LiIon batteries, at the cost of less energy density.
Aluminum electrolytic capacitor suffer from a similar problem, commonly referred to as the capacitor plague. It is noteworthy that this problem became apparent as a major issue after several decades of sucessful use of this type of capacitor.
The mentioned supercapacitor technology is quite new. The devices employ isolators which are much thinner than these of LiIon batteries, which means that "quality issues" in the manufacuting process can lead to failure easily. It appear that early large volume mass production makes such quality uisses much more likely, espically if production is "outsourced" or the technolgy is licensend to other manufacturers or even "stolen".
So while it may be quite interesting to see the effect of an internal discharge of a supercapacitor grid eneryg storage unit :-), I suspect that extremely few energy supplier are actually keen on observing this kind of failure in their premises. This of course may change in a period of only a few yea<rs if it can be shown that the new technology is sufficiently reliable and manageable.
Note that small-scale use is a different thing. A laptop computer or a car typically won't cause major blackouts or fires when failing. --Klaws 09:26, 2 December 2007 (UTC)

Reticle carbon[edit]

I added some information about Reticle Carbon. Their claims seem rather dubious, comparable with EEStor. They are searching for investors. —Preceding unsigned comment added by Lkruijsw (talkcontribs) 22:04, 26 January 2008 (UTC)

Future technology[edit]

I think it is better to make a section for 'future technology'. There we can put info about EEstor, Nano-tubes and Reticle Carbon. It is interesting for the reader that there might be big improvements for the future, but keep existing and future things separate.

Lkruijsw (talk) 22:16, 26 January 2008 (UTC)


Electric double-layer capacitor[edit]

I moved the page to Electric double-layer capacitor, as this is an official term which is also adopted in international standards (IEC) now being drafted on the subject. LHOON (talk) 19:56, 11 May 2008 (UTC)

And the IEEE calls FireWire "1394" but no one refers to it that way. While I do think this info should be included, I don't think the name should be changed (yet). —Preceding unsigned comment added by 72.87.39.179 (talk) 09:22, 1 August 2008 (UTC)

The name change makes sense. There might be new supercapacitor designs that don't use a double layer, for instance. —Preceding unsigned comment added by 71.167.58.162 (talk) 15:50, 5 May 2009 (UTC)

Disadvantages?[edit]

To a layperson like myself, this article reads as though electric double-layer capacitors are an excellent alternative to conventional chemical cells or batteries. There is no section that discusses the current technology challenges facing the real-world use of EDLC's. Could someone who knows more about this technology add a section (or modify the appropriate existing section) that puts forth why this technology has not yet permeated electric/hybrid passenger vehicle designs, etc? Thanks. Srajan01 (talk) 02:01, 9 June 2008 (UTC)

Hazards?[edit]

What about hazard of short-circuiting the supercapacitor It will become discharged very cuickly and relased energy can be harmful. —Preceding unsigned comment added by 83.8.67.68 (talk) 23:11, 4 October 2008 (UTC)

Also any dangers from internal failure (due to physical damage, manufacturing fault, aging, etc). e.g. any tendency to burst into flames like lithium ion batteries in laptops have become infamous for? Any nasty risk if caught up in a fire (I heard there is some)? 81.187.162.109 (talk) 09:16, 11 November 2008 (UTC)

This snippet does not even make sense "Due to rapid and large release of energy (albeit over short times), EDLC's have the potential to be deadly to humans. One example is the case of rescue workers accidentally discharging an ultracap in hybrids electrics during automobile accidents." Rescue workers would not discharge an ultracap during an automobile accident. There is no source cited, and it sounds like it might be just someone's conjecture (even though quite plausible). DMJ001 (talk) 04:22, 22 September 2010 (UTC)

Removed rescue workers conjecture.Munden (talk) 21:12, 4 November 2010 (UTC)

Gasoline Energy Density and Efficiency[edit]

The following sentence appears in the Concept section and is comparing the energy density of different technologies (italics mine):

For comparison, a conventional lead-acid battery is typically 30 to 40 W·h/kg, modern lithium-ion batteries are about 120 W·h/kg, and in automobile applications gasoline has a net calorific value (NCV) of around 12,000 W·h/kg operating at a 20% tank-to-wheel efficiency.

I think the value of 12,000 is the gross calorific value (GCV) and not the net calorific value. I think the NCV would be 12,000 * 0.20 which comes out to 2,400. If you search the internet for the energy density of gasoline you get 12,000 W·h/kg and it seems that this is always given without taking into account that it only opperates at 20% efficiency in an automobile. In short, I want to change the value from 12,000 to 2,400 and, seeing as how it would make a huge difference when making comparisons, I wanted to get some consensus first. —Megiddo1013 05:05, 28 October 2008 (UTC)

Theoretical maximum?[edit]

Are there any calculations of the theoretical maximum energy density that might be obtained if we had magical nanotechnology, like in Diamond Age? If you could easily make atom-thin layers of different materials and stack them, what kind of maximum capacitances could be reached? —Preceding unsigned comment added by 71.167.58.162 (talk) 15:48, 5 May 2009 (UTC)


Just a note... under *history* you have " In 2005, the ultracapacitor market was between US $272 million and $400 million, depending on the source."

I get what you mean but you might want to make it read

"In 2005, the ultracapacitor market was reported at between US $272 million and $400 million, depending on the source."

This reads better to me. —Preceding unsigned comment added by 70.65.9.67 (talk) 15:19, 25 August 2009 (UTC)

Problems[edit]

1) Why does psuedocapacitor redirect to Electric double layer capacitor? Psuedocapacitance relies on faradaic charge storage, a completely different phenomenon than EDL capacitors? 3) There is mention of an electric double layer capacitor by "ACT". Does anyone know what 'ACT' stands for? Where was the information about this gathereed from? 2) Why does supercapacitor redirect to EDL capacitor and make no mention of psuedocapacitance? Supercapacitors usually include a mix of EDL and psuedocapacitance. —Preceding unsigned comment added by 74.244.126.207 (talk) 02:06, 2 April 2010 (UTC)

I agree, this article should probably be entitled "Supercapacitor". An EDLC is a type of supercapacitor and is definitely not the same as a pseudocapacitor.Darlough (talk) 18:29, 18 April 2011 (UTC)

Lots of unexplained deletions[edit]

A lot of material was deleted without explanation on 6 May 2010 by 59.165.108.83, who made a large number of changes to this article and has made no other contribution to Wikipedia. While a lot of the deletions mentioned companies, they didn't seem to be adverts with no interesting content. A comparison is at http://en.wikipedia.org/w/index.php?title=Electric_double-layer_capacitor&diff=371381138&oldid=359506538

If anyone wants to learn about this topic, they'd be better served by the 1 May 2010 revision (http://en.wikipedia.org/w/index.php?title=Electric_double-layer_capacitor&oldid=359506538) than the present version (2 July 2010)

Things whose deletion need consideration:

  • capacitor-powered screwdriver and flashlights (have reinstated)
  • ref for activated charcoal
  • Other teams are experimenting with custom materials made of activated polypyrrole, and nanotube-impregnated papers.
  • The energy density of existing commercial EDLCs ranges from around 0.5 to 30 W·h/kg, with the standardized cells available from Maxwell Technologies rated at 6 W·h/kg and ACT in production of 30 W·h/kg, with ref. Other text on increasing energy density
  • Standard Oil's early cell design used two layers of activated charcoal separated by a thin porous insulator, and this basic mechanical design remains the basis of most electric double-layer capacitors to this day. More text and references
  • "The first trials of supercapacitors in industrial applications were carried out for supporting the energy supply to robots." This text wasn't deleted, but ref was
  • In 2005 aerospace systems and controls company Diehl Luftfahrt Elektronik GmbH chose ultracapacitors Boostcap (of Maxwell Technologies) to power emergency actuation systems for doors and evacuation slides in airliners, including the new Airbus 380 jumbo jet. Also in 2005, the ultracapacitor market was between US $272 million and $400 million, depending on the source.
  • all solid state micrometer-scale electric double-layer capacitors based on advanced superionic conductors have been for future low-voltage electronics such as deep-sub-voltage nanoelectronics and related technologies (the 22 nm technological node of CMOS and beyond).
  • Disadvantage: The amount of energy stored per unit weight is considerably lower than that of an electrochemical battery (3-5 W·h/kg for an ultracapacitor as of 2010[citation needed] compared to 30-40 W·h/kg for a lead acid battery), and about 1/10,000th the volumetric energy density of gasoline.
  • Disadvantage: As with any capacitor, the voltage varies with the energy stored. Effective storage and recovery of energy requires complex electronic control and switching equipment, with consequent losses of energy
  • Due to the capacitor's high number of charge-discharge cycles (millions or more compared to 200 to 1000 for most commercially available rechargeable batteries) it will last for the entire lifetime of most devices, which makes the device environmentally friendly. Rechargeable batteries wear out typically over a few years, and their highly reactive chemical electrolytes present a disposal and safety hazard. Battery lifetime can be optimised by only charging under favorable conditions, at an ideal rate and, for some chemistries, as infrequently as possible. EDLCs can help in conjunction with batteries by acting as a charge conditioner, storing energy from other sources for load balancing purposes and then using any excess energy to charge the batteries at a suitable time.
  • ...
  • And a great deal more, often associated with companies, but of interest.

I think the 6 May 2010 edits of 59.165.108.83 should be reverted as far as possible. It would have been easier if somebody had acted on them at the time (I, for one, didn't notice them), particularly as many were flagged "(Tag: references removed)".

Any comments?

Pol098 (talk) 19:15, 2 July 2010 (UTC)

Nobody seems to object, so have now reinstated the lot, without detailed checking. To see real changes to the article ignoring the mass deletion, compare the 1 May 2010 version with the current one.Pol098 (talk) 21:42, 5 July 2010 (UTC)

gold caps[edit]

gold caps redirects here, but it isn't mentioned at all in the article, surely if it is a common name for this kind of capacitor it should be mentioned somewhere --UltraMagnusspeak 12:30, 22 August 2010 (UTC)

no apparent connection so have blanked the redirect. - Rod57 (talk) 11:09, 8 September 2011 (UTC)

separator?[edit]

Why do we need a separator in EDLC? What is the function of the separator? Is it for stopping flow of ion and electron - if that's the case, it seem a bit redundant because the system actually does not conduct electricity even without the separator (electron cannot pass through the electrolyte ; ion cannot pass through electrode) 118.70.135.1 (talk) 03:15, 6 May 2011 (UTC)

self discharge[edit]

Can we have more details on typical self discharge rates eg in % per day ? - Rod57 (talk) 11:11, 8 September 2011 (UTC)


self-referential citation[edit]

Citation #15, http://theory.caltech.edu/~politzer/supplements/supercapacitors.pdf is a PDF of the same article. Whops! 63.82.5.67 (talk) 02:40, 13 September 2011 (UTC)

Removed. Thanks. Materialscientist (talk) 05:52, 13 September 2011 (UTC)

HIgher density thatn batteries?[edit]

I removed a sentence from the introduction which said that the power density is much higher than that of batteries, because the next paragraph just says the opposite. However, the first section after the introduction keeps saying the the power density is higher than that of batteries. Something is wrong here... --Pot (talk) 22:49, 18 February 2012 (UTC)

Inconsistent claims[edit]

" By 2006 the cost of supercapacitors was 1 cent per farad and $2.85 per kilojoule and dropping.[32] A 3 kF capacitor that was US$5,000 ten years before was $50 in 2011.[33]"

OK, so in 2006 a supercapacitor was 1 cent per farad... and dropping... to more than 1.6 cents per farad in 2011. Do these devices have anti-gravity properties as well ?Eregli bob (talk) 15:10, 8 August 2012 (UTC)

Lead section[edit]

The lead section reads a lot like an advertisement. It's rather off-putting and doesn't seem befitting of Wikipedia. A rewriting would seem to be appropriate. A.entropy (talk) 00:11, 22 December 2012 (UTC).

I edited the lead section, somewhat boldly, trying to interpret some rather strange language. It would be helpful if someone familiar with these components could review the result and verify that I got the meaning right. I added a couple of maintenance tags where I was unable to discern the meaning. The rest of the article seems to be in better shape. —[AlanM1(talk)]— 19:17, 14 December 2012 (UTC)

  • Thank you Alan for helping in grammar etc. Yes, it was a little bit boldly fom me, but I tried first to get help from the Help desk. It was said to me "be bold"! regards --Elcap (talk) 12:20, 15 December 2012 (UTC)

Graphene[edit]

Someone please add in that new info about graphene ultracapacitors. It seems promising. That is, if it's appropriate - I'm not really a wiki editor or writer. 71.62.15.51 (talk) 07:06, 7 March 2013 (UTC)inkyvoyd

Micro-Supercapacitors[edit]

The planar design of micro-supercapacitors is completely missing. — Preceding unsigned comment added by 129.132.208.75 (talk) 23:07, 5 May 2013 (UTC)

Intro[edit]

This article needs a short introduction. The opening section is far too long for this. 94.193.126.208 (talk) 22:16, 14 May 2013 (UTC)

Change in understanding: From Electric double-layer capacitor to Supercapacitor[edit]

Electric double-layer capacitors (EDLCs), invented 1957, have seen a dramatic change in understanding of their capacitive charge storage from a pure physical function between Helmholtz double-layers to an additional pseudocapacitive chemical charge storage with redox reactions, electrosorption and intercalation processes. Because nowadays (2013) an electrochemical capacitor is not only an EDLC anymore the question comes up how to name this very special capacitors.

Generally in science publications all the different developments of the last years are united under the term “electrochemical capacitors”. But if a development gets a discrete component from a manufacturer, the names are manifold. Supercap, Ultracap, Goldcap, Greencap, a lot of manufacturer related names exist.

A look through the science literature of electrochemical capacitors shows, that roughly 70 to 80 % of the authors uses the term “Supercapacitor”. (see: A Bibliometric Analysis of the International Literature in Supercapacitors, Francesco Lufrano* and Pietro Staiti, Int. J. Electrochem. Sci., 4 (2009) 173 – 186 PDF)

A google research gives 730,000 results for Supercapacitor, for Ultracapacitor only 363,000 but for Double-layer capacitor Google gives 1,540,000 results. (Date: 2013-05-07)

Hierarchical classification of supercapacitors and related types

That means, that as of 2013 the term double-layer capacitor is used in public linguistic usage, the term supercapacitor in science publications. Because in the broad public knowledge the new development of pseudocapacitance is not known, otherwise the science results are clear and available, that every EDLC not only has a double-layer capacitance but also a pseudocapacitance and nearly all new developments are trying to enhance the properties of the capacitors by increasing the pseudocapacitance the term double-layer capacitor is not correct anymore.

This is the reason a complete new written article now use the term supercapacitor. The reasons why in the science the term supercapacitor is prevailed instead of the term ultracapacitor are surely first the respect for B. E. Conway, who coined the term supercapacitor, and the second reason may be that the often used term “ultracapacitor” is used by Maxwell, the market leader, like a trade name for their capacitors, and that smells a little bit like advertising.

Please help to better the new detailed and bulky article supercapacitor, written by a German, by editing grammar, style, cohesion, tone, or spelling. --Elcap (talk) 08:02, 16 May 2013 (UTC)

Merge discussion[edit]

This page has been tagged for merging with [Supercapacitor], because most of the information on this page is duplicated there. If a merge is desirable, any information here which would benefit that page should be moved. If no merge is to be done, then redundant information on [Supercapacitor] should be deleted and this article improved to meet Wikipedia guidelines. Todd Vierling (talk) 18:24, 18 August 2016 (UTC)

Hi Todd, as main author of the Supercapacitor article I agree in merging the present EDLC article into the Supercap article. The reason why I did it not at that time I wrote Supercaps was to help readers to understand the new cognition by using EDLC and leading readers with this article to Supercaps. --Elcap (talk) 09:41, 23 August 2016 (UTC)

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