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Breakthrough In Use of Graphene For Ultracapacitors
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."
Laptops, however, will _still_ be getting 1 1/2 hour of unplugged life tops :(
Is this another factor of 2 on top of EEStor's still-unproven claims? How many more breakthroughs is it gonna take before something actually happens?
Sorry but how does this work? "Graphene has a surface area of 2,630 square meters, almost the area of a football field, per gram of material" so its actually the size of a football field?
More or less than traditional batteries when production is at commercial levels? Will they be prohibitivly expensive to have electric cars using these?
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.
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
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If 1 gram of graphene has the surface area of a football field, what's the surface area of a football field of graphene?
Human resource usage expands to consume all available resource...
That is the history of humanity in one sentence. In fact, it can be generalized to all life.
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It's also the distance between the electrodes. The thinner the dielectric layer, the more charge the capacitor will hold. The problem is then to avoid the electrical breakdown of the dielectric.
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...
I have been a user for about 10 years. This ends Feb 2014. The site's been ruined. I'm off. Dice, FU
In my day we had to calculate everything as VWs in the Library of Congress.
Wow...with a surface area like that.
Imagine if you had two phone books made out of graphene - and interleaved their pages.
You'd, like, never be able to pull 'em apart.
Don't worry that the Graphene layer would rip. It's a very, very strong material and the connections between the atoms are strong conjugated double-bonds.
This is the same structure as in Carbon Nano Tubes and Fullerens (C60), just flat (and not cylindrically or spherically rolled up).
The problem to implement Graphene based technologies is rather the synthesis of it, since it's not yet easily possible to create a homogeneous Graphene layer on a large area (i.E. at my Applied Physics institute they create Graphene layers that are not even 1 mmÂ).
When I saw a capacitor that can charge and discharge rapidly, the first thing came to my mind was actually memory. I wonder how practical is graphene capacitor used as a memory storage cell compare to SRAM or DRAM we have today.
is it american football or european football (=soccer?)
or should i use the delorean to go back to when article was posted ?
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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 well what the limits are. The limits are about four powers of ten higher than these neophytes are talking about.
Read the fine wikipedia entry. It's not replacing the plate, it's replacing the granular activated charcoal in existing ultracapacitors.
And is that "football" or "Soccer"?
An American football field is 360 by 160 feet including end zones, or 5351 m^2. A soccer pitch is significantly wider; it can be anywhere from 100 by 64 m to 110 by 75 m, or 6400 to 8250 m^2.
Are we talking about the paper itself, or when you applied it to your posterior?
And did you say "holy shit!" upon surveying the devastation after it went off?
Inquiring minds want to know!
Again, the liability issue is a major factor. Think of the lawsuits that would happen when someone went to wipe their arse.
If his fetish is, say, truckers and fat mexican grannies with mustaches, do you still want to be the cameraman?
Must... resist... urge... to verify... Internet Rule 34....
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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 supercapacitors increase the energy they can store dramatically and these graphene type plates seem to provide a 2-fold increase over other supercapacitors.
So why can't these technologies be used together? EEStore is claiming 52 KWH per 400 lbs. Change EEStores traditional capacitor into a graphene plate system and get another 200 X boost for a total of 10.4 MWH in 400 lbs or 26 KWH per pound! At that energy density you could drive a sedan about 31,000 miles per charge.
Now I know EEStore hasn't produced a 52 KWH unit, but some aspects of the technology has been proven and even sceptics think they could acheive half that energy density...which is still a lot. Carbon supercapacitors are already on the market.
Does anyone with an approproate background know why this couldn't work?
The single reason is Sharks, man. Sharks.
Caps are the only way to power a petawatt laser, and you'll need an energy storage to use the lasers unplugged and mounted on sharks' head.
So it's supercaps for you.
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Or until we invent fertilizer (18th century)...for food
Or until we invent pesticieds/herbicides...for food
Or until we invent underground farming...for food
Or until we invent land reclimation...for land
Or until we invent skyscrappers...for land
Or until we invent seasteading...for land
Or until we invent lunar colonies...for land
Or until we invent large dams...water, food and power (oil)
Or until we invent water treatment...water
Or until we invent reverse osmosis distillation...water
Or until we invent atmospheric condensers...for water
Or until we invent nuclear fission...for power (oil)
Or until we invent fusion...for power (oil)
Or until we invent photovoltaics...for power (oil)
Or until we invent bio fuels...for power (oil)
Or until we invent direct CO2 conversion to hydrocarbons...for oil (from power)
and a big one is:
Or until we invent a trully good electrical battery, one that stores a lot of energy, has high power density, does not wear out, does not use environmentally harmfull components and is cheap (something like these graphene supercapacitors will be under mass production)...for oil
My point is simple. Humanity ran out of resources about 20,000 years ago. We are designed to be hunter/gatherers. The earth can only support a few million hunter/gatherer human beings. It was only through the invention of agriculture and other technologies that we are able to continue. While we will probably ALWAYS have some resource limitation (probably power) there are technologies that exist now that if used can prevent any Malthusian collapse for the indefinet future.
I wonder what the ESR of a 1-atom thick layer of graphene is. I can't imagine it's that low. That kinda blows it out of the water for applications that have big current transients (like DC/DC controllers, parallel RAMs, anything with a lot of parallel switching I/O, really)
We just have to tunnel them somewhere and then tunnel them back when they are needed.
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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.
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This is all very nice, but it's been my own experience that not only can caps charge at a rate much higher than a battery, they can also discharge at a rate much higher than a battery.
As in instantaneous.
So; are there any ideas as to how to keep such a super-cap's discharge rate down to a less-than-catastrophic rate when a failure mode is encountered?
Regards;
http://en.wikipedia.org/wiki/EEStor It's going to hit the market next year; 1513W/h per L of power at about $2100 / unit @ 682WH/kg that's far higher than any other tech out there.
Your first problem is expecting rated performance from a component well past its lifespan.
Play within the well-documented performance characteristics of components and you will (most of the time) be just fine. There will be a few occasional exceptions, but this happens with all energy storage devices, as laptop fires and gasoline fires have taught us. Caps are no different.
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In case anyone is interested in following eestor, there is a website with a forum dedicated to talking about the technology. The person who runs this has managed to get some interviews with some people and on the 22nd, they are going to submit some questions to Ian Clifford. http://www.theeestory.com/
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Large scale power applications, such as smoothing out the production of solar or wind energy would be worth billions if it meets the engineering designs.
Energy density is not a big factor for non-mobile static devices. Also, safety can be enhanced by putting the caps inside concrete bunkers.
However, high internal resistance is an obstacle as it limits discharge rate and it also causes energy losses. I suspect that the more serious obstacle to both mobile and non-mobile applications could be leakage (i.e. How long before the charge leaks away because of internal resistive paths?)
Couldn't ultracaps still be useful used in conjunction with batteries with an intelligent battery management system?
As far as I understand ultracaps can take a charge and release a charge faster, they can withstand more cycles, and they can be safely fully depleted.
So it would seem that ultra caps would be ideally suited for capturing regen braking power and then releasing this energy once the car pulls away from the stop light. This would allow more regen energy to be captured and saving additional wear on conventional brakes. This would also save the chemical batteries from taking small bursty charging that leads to reduced lifespan.
The number of ultracaps needed to handle this task wouldn't be that many so the power to weight ratio might not be acceptable. I think it would be interesting to see how it stacks up to the F1 KERS flywheel and which would be better for consumer applications.
http://en.wikipedia.org/wiki/Regenerative_braking
The Flybrid F1 KERS System weighs 24 kg and has an energy capacity of 400 kJ after allowing for internal losses. A maximum power boost of 60 kW (81.6 PS) for 6.67 sec is available. The 20-cm diameter flywheel weighs 5.0 kg and revolves at up to 64,500 rpm. Maximum torque is 18 Nm. The system occupies a volume of 13 liters.
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How about making a capacitor that uses the platters of a hard disk as the plates? The idea would be to combine the power source and hard disk on a laptop, to save space and weight.