Forgot your password?
typodupeerror
Power Science

Breakthrough In Use of Graphene For Ultracapacitors 250

Posted by kdawson
from the high-credit-limit dept.
Hugh Pickens writes "Researchers at the University of Texas at Austin have achieved a breakthrough in the use of a one-atom thick graphene for storing electrical charge in ultracapacitors. They believe their development shows promise that graphene could eventually double the capacity of existing ultracapacitors. 'Through such a device, electrical charge can be rapidly stored on the graphene sheets, and released from them as well for the delivery of electrical current and, thus, electrical power,' says one of the researchers. Two main methods exist to store electrical energy: in rechargeable batteries and in ultracapacitors, which are becoming increasingly commercialized but are not yet well known to the public. Some advantages of ultracapacitors over traditional energy storage devices such as batteries include: higher power capability, longer life, a wider thermal operating range, lighter, more flexible packaging and lower maintenance. Graphene has a surface area of 2,630 square meters, almost the area of a football field, per gram of material."
This discussion has been archived. No new comments can be posted.

Breakthrough In Use of Graphene For Ultracapacitors

Comments Filter:
  • EEStor (Score:5, Interesting)

    by paul248 (536459) on Wednesday September 17, 2008 @03:03AM (#25035531) Homepage
    Is this another factor of 2 on top of EEStor [wikipedia.org]'s still-unproven claims? How many more breakthroughs is it gonna take before something actually happens?
    • by QuantumG (50515) *

      There's 10 years from lab to product.. at least.

    • Re:EEStor (Score:5, Interesting)

      by smilindog2000 (907665) <bill@billrocks.org> on Wednesday September 17, 2008 @06:28AM (#25036423) Homepage

      No. This isn't even close to EEStor's claimed energy density. I personally put EEStor in the BS bucket a long time ago, but last week I found some very interesting news on wikipedia's EEStor page [wikipedia.org]: competitors. It seems that several companies now have patents on materials they claim are similar in energy density to EEStor's claims. We may not get ultra-cheap batteries for electric cars any time soon, but at least the raw science seems to be real.

      • Re:EEStor (Score:4, Interesting)

        by JamesP (688957) on Wednesday September 17, 2008 @08:06AM (#25036947)

        Yeah, except there are also patents on glass pyramids that keep razors sharp, cures cancer or something like that. And don't forget the patents on playing with your cat with a laser pointer.

        When people say anything can be patented, they're pretty much spot on.

    • As I understand EEStor's patent, they are creating a dielectric that they claim has an extremly high breakdown voltage. This allows them to make it micron's thick and still run the voltage up to 3500 Volts. They then sandwich this between two aluminum plates. So other than the dielectric, EEStore is creating a traditional capacitor.

      Supercapacitors seem to provide about a 100-fold increase over traditional capacitors. By creating more surface area to store charge the activated carbon/electrolyte supercap

  • More or less than traditional batteries when production is at commercial levels? Will they be prohibitivly expensive to have electric cars using these?

    • Re: (Score:3, Insightful)

      by kestasjk (933987)
      Depends; we don't yet know how to commercially make graphene. This is a shame because in addition to ultracapacitors it could also be used to make integrated circuits. It's the same problem as with nanotubes; lots of great uses already found, now we just need to figure out how to make them.
  • by loshwomp (468955) on Wednesday September 17, 2008 @03:05AM (#25035537)

    Some advantages of ultracapacitors over traditional energy storage devices such as batteries include: higher power capability, longer life, a wider thermal operating range, lighter, more flexible packaging and lower maintenance.

    By contrast, two advantages of batteries are 1) vastly higher energy density, and 2) the fact that they exist.

    • by RuBLed (995686)
      And I could put it on the roof during a hot day to recharge it.
    • by OldMiner (589872) on Wednesday September 17, 2008 @04:03AM (#25035801) Journal

      I know you're trying to be cleverly ironic here, but you can buy ultracaps today [digikey.com]. The higher power capability, swifter charging, longer life, wider thermal operation range, more flexible packaging, and lower maintenance are already there and have been for years [edn.com] along with the superior environmental characteristics. However, "lighter" isn't true yet, since the energy density of an ultracap is an order of magnitude lower than that for a dry cell [wikipedia.org]. That's why a breakthrough such as in this article is such a big deal.

      If grapheme could reliably be utilized to create the sort of energy density posited here, any application requiring large amount of batteries (such as electric cars) would benefit greatly. Unfortunately, since capacitors are more prone than dry cells to losing energy over time due to internal resistance, this won't eliminate the need for dry cells entirely.

      • Re: (Score:3, Interesting)

        by Shotgun (30919)

        Unfortunately, since capacitors are more prone than dry cells to losing energy over time due to internal resistance, this won't eliminate the need for dry cells entirely.

        I don't see them replacing batteries at all, but augmenting them instead. Batteries are limited in the power they can absorb. They are much more efficient with storing energy if you spread the charge out over a longer period.

        The efficiency of regenerative braking in cars is limited by the ability to pump the energy recovered by the brakes back into the batteries. Lots of energy is generated in a few seconds, but there isn't enough time to force that energy into the batteries.

        The big benefit from ultracap

        • by loshwomp (468955) on Wednesday September 17, 2008 @10:23AM (#25038613)

          I don't see them replacing batteries at all, but augmenting them instead. Batteries are limited in the power they can absorb.

          Yes, but the limit isn't especially limiting in practice. Power density is important, but any modern battery with sufficient energy density to be useful in the EV industry has plenty of power density. Some types of lithium cells (let's pick A123 since they're well known) have outrageous power densities (hence their use in power tools where you want high torque) but rather poor energy density, yet their energy density is an order of magnitude better than the best ultracaps.

          Round trip energy efficiency for lithium type batteries is already on the order of 90%. Even if your hypothetical ultracap system were 100% efficient, you're only looking at an ~11% improvement. But of course your hypothetical system won't be anywhere near 100% efficient, and the cap voltage is dramatically higher and the discharge curve is different, so you have to account for additional power electronics losses involved in moving the charge back and forth between the battery system. And if you just doubled the complexity of your power electronics, you've added significant cost and weight.

          In short, I'm an electric vehicle engineer, and I have yet to see a situation where adding caps makes more sense than adding more cells to the battery.

    • by F34nor (321515)

      By contrast six advantages of EMBs (Electromechanical Batteries) or Flywheel Batteries have over both lead acid and ultracapacitors are that they have the highest power density of any energy storage system currently available, thye are so reliable they can be buried or even sent into space, they hold huge amounts of power, they can be recharged very quickly, they do not burst into fire, they are not hazardous and you can even buy them today.

      Specific Power
      EMB (5-10kW/kg)
      Lead Acid (0.1-0.5kW/k

    • by Tumbleweed (3706) *

      By contrast, two advantages of batteries are 1) vastly higher energy density, and 2) the fact that they exist.

      I've found existence to be highly overrated.

    • The single reason is Sharks, man. Sharks.

      Caps are the only way to power a petawatt laser [slashdot.org], and you'll need an energy storage to use the lasers unplugged and mounted on sharks' head.
      So it's supercaps for you.

  • by metalcup (897029) <(metalcup) (at) (gmail.com)> on Wednesday September 17, 2008 @03:16AM (#25035599)

    I found this image from Nature magazine useful in imagining how 1 gm of graphene can have such a large surface area..

    http://www.nature.com/nature/journal/v427/n6974/fig_tab/nature02311_F1.html [nature.com]

  • If 1 gram of graphene has the surface area of a football field, what's the surface area of a football field of graphene?
    • Re: (Score:3, Funny)

      by RuBLed (995686)
      45 miles per gallon, which I say is not bad...
    • by Ihlosi (895663) on Wednesday September 17, 2008 @03:35AM (#25035689)

      If 1 gram of graphene has the surface area of a football field, what's the surface area of a football field of graphene?

      One football field, of course. They're both units of area. Now, if you were to ask what the surface area of a VW-Beetle-equivalent of graphene is ...

      • by Ihlosi (895663)
        One football field, of course. They're both units of area. Now, if you were to ask what the surface area of a VW-Beetle-equivalent of graphene is ...

        Oh, and before I forget, that's going to be a large number in football fields. Use Rhode Islands instead (or, if the number is still too large, Texas').

      • by bakes (87194)

        One football field, of course

        But how much would that weigh?

      • by julesh (229690)

        Now, if you were to ask what the surface area of a VW-Beetle-equivalent of graphene is ...

        About half the size of Delaware.

        • by Jesus_666 (702802)
          And then we have a graphene sheet half the mass of Delaware and its are would be-- STOP! This madness has to end now before the whole planet is enveloped in a think layer of graphene sheets!

          Get your torches! We have to stop these mad scientists before they destroy the world!
    • Re: (Score:3, Funny)

      by tekrat (242117)

      That would be a football field to the power of a football field.

      I think a more relevant question is: if 1 gram of graphene has the surface area of a footbal field, what weight are the football players? And is that "football" or "Soccer"?

  • Safety ? (Score:3, Insightful)

    by CdBee (742846) on Wednesday September 17, 2008 @03:48AM (#25035729)
    Ultracapacitors may have proven brilliant usages (especially in transport and electricity storage) but is anyone else nervous about being around that degree of stored energy?

    As a teenager I was slightly injured by a 50-year-old 3300mfd cap I'd salvaged from a valve radio, which went off like a small bomb despite only holding 12 volts at the time. I for one would treat an ultracapacitor as a potential source of devastation until proved safe by a long period of use...
    • Re:Safety ? (Score:5, Interesting)

      by Genda (560240) <marietNO@SPAMgot.net> on Wednesday September 17, 2008 @04:14AM (#25035847) Journal

      That's one of the serious problems with any exceptionally high density energy storage technology. How do you keep the genie in the bottle, and protect the public from the critically stupid in our society.

      There was a very cool design for a car whose power source was a high mass flywheel in a magnetic housing. You go to a power station, and the station would spin your flywheel up to some insane RPM rate. The possibility of using this in a hybrid vehicle meant you could get really excellent energy storage and return, it was very efficient.

      The only drawback, was that if the bloody thing ever got out of containment, you had a death dealing juggernaut that would buzz-saw a swatch of destruction through the middle of wherever the now flying flywheel was pointed. Then some bright child imagined such a flywheel driven vehicle on a crowded freeway causing a chain reaction of thousands of other similar vehicle, and suddenly you pretty much have a scenario for mass destruction that looks like front row seats to Armageddon.

      Whatever technology you finally pick, you'll need to make it very safe, or decide it's a Darwinian herd thinning tool.

      • Re:Safety ? (Score:4, Interesting)

        by evilviper (135110) on Wednesday September 17, 2008 @10:01AM (#25038285) Journal

        The only drawback, was that if the bloody thing ever got out of containment, you had a death dealing juggernaut that would buzz-saw a swatch of destruction through the middle of wherever the now flying flywheel was pointed.

        Actually not.

        The RPM rate is so high that flywheels get insanely hot as soon as the vacuum is broken, and it has to deal with friction from the air.

        With metallic flywheels, this means it breaks apart, and you've got thousands of bits of white-hot magma flying through the air, in a straight line from the direction the flywheel was spinning. Of course your car is going to turned into swiss cheese, and the two cars directly in front/back of you are likely to get damaged as well, but it's not Armageddon.

        With carbon-fiber flywheels, the flywheel material is completely incinerated instantly, and DOESN'T risk turning into such deadly projectiles. HOWEVER, you have to have a very good design to deal with the HUGE amount of unimaginably hot air now erupting out the top of the flywheel housing. Mount it properly, eg. externally, on the roof of your car, with a nice thick base-plate, and your vehicle quite quite likely wouldn't face any structural damage. Though, you can definitely expect to need a new coat of paint.

      • The fact of the matter is, it takes "X" number of joules of energy to move your typical car 300 miles.

        Whether that energy is stored in a tank of gasoline, a capacitor, batteries, or a spinning flywheel, you still have X number of joules of energy that have to be safely stored and protected against unrestrained liberation.

    • Re: (Score:3, Interesting)

      by Ihlosi (895663)
      Ultracapacitors may have proven brilliant usages (especially in transport and electricity storage) but is anyone else nervous about being around that degree of stored energy?

      Hate to break it to you, but if you replace the ultracapacitor with a battery of the same volume, or, heaven forbid, the same volume of gasoline, you're looking at even _more_ stored energy, and no one's too worried about that.

      • Re: (Score:2, Interesting)

        by Kitsune (8349)

        Genda may not of quite nailed it on the head in writing but does have a point: capacitors have the ability to discharge a huge amount of their stored energy at once. All the people I know that used to fix TVs have stories of being thrown across their rooms by forgetting to bleed the charges on (non-super-cap) capacitors and letting something short. In comparison, batteries and gasoline even seem have a limit on the amount of discharge they provide in any period... though a comparable example for gasoline mi

      • Re:Safety ? (Score:5, Informative)

        by Eivind (15695) <eivindorama@gmail.com> on Wednesday September 17, 2008 @07:05AM (#25036611) Homepage

        More energy, true, but slower release-rate.

        A battery has significant internal resistance, even if you short-circuit it the power-levels are limited. (high, but limited)

        A capacitator can recharge significantly faster.

        Put differently, the thing may only hold 10% of the energy in a battery. But if that energy is released a hundred times quicker, you're still looking at hell of a bang.

        • Re: (Score:3, Insightful)

          by CdBee (742846)
          Thanks, that was part of my point. Capacitors have in common with Lead-Acid accumulators the ability to dump biblical amounts of power in an instant... and it may be easier to unthinkingly short a circuit than it is to unthinkingly introduce a flame to a fual tank

          I drive a diesel car. It feels safer (low-volatility compared to petrol)
    • Re: (Score:3, Interesting)

      by mangu (126918)

      I was slightly injured by a 50-year-old 3300mfd cap I'd salvaged from a valve radio, which went off like a small bomb despite only holding 12 volts at the time

      I doubt those numbers. Capacitors in valve radios were more like 32uF, and typically work at hundreds of volts. Values like 3200uF are used in low-voltage power supplies, not in valve equipment, unless it's some very specialized equipment from the 1950s with hundreds of valves, perhaps.

      But you are right that charged capacitors can be dangerous. I mys

      • Re: (Score:3, Interesting)

        by CdBee (742846)
        Probably my memory playing up. On learning that I was developing an interest in electricity and computers, a local elderly gentleman (in the real, British, sense) gifted to me a large amount of old electrical equipment to play with and learn from

        Most of it dated from the mid 40s to early 50s and was 40-50 years old at the time, I learned a lot from it but my memories may be confused as to what came from where. I remember a love of the design of the large tube capacitors with their crenellated electric-bl
    • I see no reference (anywhere) to the likely internal resistance of these posited ultracaps. It's great that you can store all that energy in them, but if it all turns to heat when you try to get it out, it's not much use.

    • by evilviper (135110)

      but is anyone else nervous about being around that degree of stored energy?

      I drive my car every day, sitting in front of a tank with HUGE amounts of energy, in the form of gasoline... So no.

      I for one would treat an ultracapacitor as a potential source of devastation until proved safe by a long period of use...

      Capacitors are CURRENTLY used for high instantaneous storage/use of power. They aren't yet used for energy STORAGE. As soon as they are seeing significant use as battery replacements, you can expect

  • or should i use the delorean to go back to when article was posted ?
  • It's golly-gee wonderful if they can make a one-atom thick graphene sheet. Give them a lollipop.

    But in making a capacitor, you need other attributes than just thinness. You need a capacitor plate that can carry current, remain in place in the face of strong electrostatic fields, be compatible with dielectrics, be reliable, and be manufacturable.

    A one-atom thick sheet is not going to be able to do any of those things. Capacitor makers have been depositing thin electrodes for 60 years now. They know full

    • by argent (18001)

      Read the fine wikipedia entry. It's not replacing the plate, it's replacing the granular activated charcoal in existing ultracapacitors.

Any sufficiently advanced bug is indistinguishable from a feature. -- Rich Kulawiec

Working...