Breakthrough In Use of Graphene For Ultracapacitors 250
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."
Re:How? (Score:5, Informative)
graphene surface area (Score:5, Informative)
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]
Re:Still... (Score:2, Informative)
A relative of mine's Panasonic Toughbook CF-W5 is rated 11 hours and actually gets her 5-6 hours of word processing and internet on battery. Maybe you should try better-quality laptops.
Re:How? (Score:5, Informative)
Yes, massively folded. Similar technology has been in used for many years to produce multi-Farad 'dime' capacitors, whos surface areas start around the size of a tennis court and go up from there.
These sorts of capacitors have very high capacitances (in the multiples, even tens of Farads) and a 20-50 year life span (or longer depending on how they are built), but also tend to only be able to be charged to fairly low voltages (3v, 5v, etc), and also have fairly high internal resistances (though this might be different for the newer Graphene-based caps), limiting the discharge rate.
This means they won't be replacing batteries any time soon, but the advances we're seeing are pretty cool.
We mostly use these things to run real time clock chips and provide backup power for static ram... i.e. very low current applications.
-Matt
Re:How? (Score:2, Informative)
Surface area is the size of a football field, but because it is very thin it can be rolled up in to something very small.
Think about a roll of toilet paper. When rolled up it is about 10cm x 10cm x 10cm. If you roll it out it might be 50m long.
Re:How? (Score:3, Informative)
Look into how capacitors [wikipedia.org] work. It's capacity is largely based on the surface area of internal parts. You get that by making things thin. Thin is huge for capacitors, even the normal kind you have in the computer you used to type that post. Capacitors are all wound up inside and packed nicely. They *do* break on occasion and get icky gooey stuff everywhere, but it's not exactly so fragile as to be caused by a speed bump. Otherwise we'd have a lot of dead cars on the road.
Re:How? (Score:3, Informative)
So why not just use toilet roll as a capacitor?
The cylinder capacitors that handle the bigger charges most of the time pretty much look just like that if you crack them open.
Re:How? (Score:3, Informative)
It's capacity is largely based on the surface area of internal parts.
It's also largely based on the inverse of the distance between internal parts. And this distance also decreases when you make things thinner.
Thin is huge for capacitors,
Yep, it's huge^2, even, since you're increasing surface area and reducing the distance if you make the internal structures thinner.
Re:Safety ? (Score:5, Informative)
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:Here's the deal (Score:4, Informative)
No but the organisms which produced the oxygen first probably weren't the ones which needed it to survive, oxygen was waste, a poison to them.
Although there are animals and plants which by one means or another make more space for themselves to live in.
Re:Safety ? (Score:5, Informative)
Large-scale systems of this sort are actually in use, just not inside vehicles. There are some electric train systems that use it to recapture energy from trains arriving in the station, and then assist trains as they accelerate out of the station.
Rule 34 (Score:4, Informative)
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 [xkcd.com]....
Ghaaa !!! 22k+ pages found [google.ch]. The Google, it doesn't do nothing.
What about ESR? (Score:2, Informative)
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)
Re:EEStor AND Graphene (Score:4, Informative)
No, capacitors don't have to. In fact even the tiny capacitors you can get at radio shack hold enough power to fry most electronics if it were released at once.
Capacitors only release all the power they hold at once when they fail catastrophically...then they blow up.
However the output voltage of a cap is related to the energy they store so as the output voltage must be adjusted as the capacitor discarges to maintain usable voltage. By oncreasing the resistance in the circuit you can slow the discharge rate of a capacitor to usefull levels.
Re:Here's the deal (Score:3, Informative)
There's a fungus growing inside the post-meltdown reactor at Chernobyl that appears to be using the radiation as an energy source (capturing the energy with melanin I believe). Using radioactive waste instead of sunlight, check.
There's a bacteria found in a factory out-flow somewhere, capable of digesting certain nylon byproducts. Eating garbage, check.
As for tailpipe fumes... well quite a lot of things use CO2, I believe they're called plants. The other gases in exhaust fumes are still fairly poisonous but I'm sure evolution will get on top of that one soon.