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."
EEStor (Score:5, Interesting)
Re:How? (Score:1, Interesting)
What is likely (already) happening is that supercap properties are being combined with conventional batteries. Creating supercap-battery hybrids.
A project doing this showed promising results in tests until the partner handling the patent found out they weren't allowed to collaberate with other battery companies after all. Fools...
punk teenagers (Score:1, Interesting)
In my day we had to calculate everything as VWs in the Library of Congress.
Re:Safety ? (Score:5, Interesting)
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:3, Interesting)
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:How? (Score:5, Interesting)
Because it doesn't have to layers that are insulated against each other?
However, if you're talking about two toiled rolls, soaked in electrolyte, with an insulator between them, rolled up and packaged nicely, then yes, you can use that as a capacitor (we'd all be thrilled about a capacity measurement and some pictures when you try it out, please?).
Re:Safety ? (Score:3, Interesting)
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 myself once got a strong shock from a capacitor that had been disconnected from a circuit for about ten minutes, after that I learned to discharge any capacitor in a high voltage power supply. An innocent looking yet dangerous equipment is the normal photographic flash. There you can find, typically, a 200uF capacitor charged to 200 volts.
Re:Still... (Score:3, Interesting)
http://www.quantumg.net/eeepc.txt [quantumg.net]
Re:Safety ? (Score:2, Interesting)
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 might be to finely mist the all the gas into a well oxygenated room and throw in a match. Wheee! ;)
That said, as it's so fast to charge, hopefully it'll become a practical tech at some point. It'd be great to just be able to plop my laptop/phone/whatever on the tray for a few seconds then walk away with a fully charged battery.
Re:Safety ? (Score:1, Interesting)
How did they plan to fight the angular momentum?
Re:Memory any one? (Score:3, Interesting)
I wonder how practical is graphene capacitor used as a memory storage cell compare to SRAM or DRAM we have today.
Err ... you do know that one of the main differences between SRAM and DRAM is that the latter uses a capacitor (and fewer transistors) than the former per memory cell, and therefore requires to be refreshed occasionally (hence "dynamic", as opposed to "static" memory which will keep its contents as long as it is supplied with power)?
I'd say that graphene capacitors are as uninteresting as it gets as far as memory technology goes, sorry.
Re:EEStor (Score:5, Interesting)
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:Safety ? (Score:4, Interesting)
Simple - mount it in a gimbal [wikipedia.org]
Re:Safety ? (Score:2, Interesting)
The way I'd do it is by having two contra-rotating flywheels, one on top of the other. It doesn't solve all the problems, but it gets rid of the most obvious one.
Re:EEStor (Score:4, Interesting)
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.
Re:advantages of batteries (Score:3, Interesting)
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 ultracapacitors will be as a front end to the batteries. They can absorb nearly all the braking energy as fast as the pumps can generate it, and then pump it into the batteries at a rate the batteries like. If the driver accelerates before the energy is pushed back into the batteries, the drive motor would pull energy from the lower resistance ultracapacitor, making life even easier for the batteries.
Re:Here's the deal (Score:4, Interesting)
Remove the bottleneck for growth, and the expansion will continue till the next bottleneck stops growth.
In our case, with our 'intelligence' we appear to be stretching all our resources to the extreme... till our growth is limited by food, water, land, and perhaps other resources like oil. Then we either have starvation (of food, or of oil or of whatever) or wars (that knock off population).
Re:Safety ? (Score:3, Interesting)
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-blue cases and stamped capacity figures, which was only slightly attenuated when one of them nearly blew my head off...
Re:Safety ? (Score:4, Interesting)
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.
Or until we invent... (Score:5, Interesting)
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.
Re:advantages of batteries (Score:5, Interesting)
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.
Re:Or until we invent... (Score:5, Interesting)
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
Well, let's compare the modern automotive li-ions to see how well they meet your requirements:
* "A lot of energy" -- The automotive li-ions on the market are generally 90-110Wh/kg (not as good as the ~160Wh/kg for conventional li-ion). There are about a dozen different chemistries in the lab right now that offer 2x, 3x, or more energy density than this; I could go down the list if there was interest. Now, while this is notably less than gasoline, there's a couple factors that have to be considered, such as the fact that most of the energy in a battery goes into providing torque to the wheels, while only a tiny fraction of the energy in gasoline does (most gets wasted as heat). Secondly, batteries are heavy while electric motors are light; internal combustion engines are heavy while gasoline is light. It's an opposite paradigm; in a typical electric car equivalent, batteries are competing for the space and weight freed up by the lack of need for an internal combustion engine, transmission, and all of the supporting hardware, while the motor is about the same size and weight as a full fuel tank. As a result, to match a typical car in range for a given amount of weight, you need about 300Wh/kg. So, they're not a match for gasoline cars yet, but they very well could be in a few years. Even as it stands, it's not hard to get enough batteries to take you for two hours at highway speeds (general highway safety advice is that you're supposed to take a break every two hours or so).
* High power density: Already got this one licked. 100 kilograms of lithium phosphate batteries will give you up to ~250kw or so (335 electric horsepower, which due to the wider max power operating range, is more like a gasoline car with 500hp or so). 100 kilograms of titanate cells will give you 2-3 times as much. Even despite having far less research put into them, EVs are already challenging gasoline cars for speed records (esp. accel, but even top speed, such as with the Eliica). The motors and inverters are actually the limiting factor, not the power source.
* Lifespan: LiP and stabilized spinels will lose 20% capacity in ~7000 "gentle" cycles or so, while the titanates take tens of thousands to lose that much capacity. They also show little to no loss of capacity with age, as they resist lithium plating. By "gentle", this means a cooled pack, charge times of at least a couple hours, and discharge times of at least a couple hours. Under abusive conditions -- overheating, 5-20 minute charges, 5-10 minute (impossibly fast) discharges, etc, you'll get ~1000 cycles out of LiPs and spinels, more out of the titanates. Under a normal mix of fast and slow charging, with reasonable discharge times, you can expect a couple thousand cycles. For a car with 150 miles range, 1000 cycles = 150,000 miles, so a couple thousand cycles means around half a million miles. Adjust appropriately to your situation.
* Does not use environmentally harmful components: Two common types of batteries -- PbA and NiCd -- are highly toxic, and must be recycled to avoid serious environmental consequences. NiMH aren't great for the environment, and should be recycled, too, but they're not as bad as PbA and NiCd. Li-ion with a LiCoO2 cathode, like conventional li-ion and AltairNano's titanates, are minorly toxic; it's not as bad as NiMH, but it'd be best to recycle, and proper disposal is required in most places. LiP and spinel li-ion are nontoxic; the worst thing you can say about them is that their electrolyte is corrosive.
* Cheap: Current prices for LiPs in bulk straight from the manufacturers is about $0.50-$0.60Wh/kg, which most kinds of cars, is already low enough that the purchase price premium can be amortized into the car's operation
Re:EEStor AND Graphene (Score:3, Interesting)
Look up introductory electrical engineering stuff, searching for RC time constant and RC curves. This appears to be a good page. [tpub.com]
The overall idea is that charge cannot move instantly through a resistance. Think of a capacitor like a bucket of water, and the resistor a hose hooked to the bottom of the bucket. The bucket can drain only as fast as the hose is wide. And the less water there is in the bucket, the slower it will drain (since there is less weight/pressure pushing on the water at the bottom of the bucket where the hose is.)
Re:Or until we invent... (Score:3, Interesting)
Lithium is not scarce at all. Lithium is about as common worldwide as some common steel alloying agents, such as vanadium, chromium, and nickel. Lithium carbonate, the "raw" form most commonly purchased commercially, costs about $6/kg. To produce it from seawater, which is a virtually boundless supply, is estimated at $22-$32/kg. 1kWh of li-ion batteries takes about 1kg of lithium carbonate -- thus, a 30kWh pack, with the lithium produced from seawater, with pessimistic assumptions, takes under $1,000 worth of lithium. Yet there's far more lithium on land than you'd ever need for li-ion batteries.
There's a common misconception that most people have about natural resources when they see a "reserves" figure. Reserves figures are for *current technology* with sales at *current prices*. When either the price rises or the technology advances, reserves increase. Not just a little, but with scaling exponential to the advance in technology or prices. The best deposits of any resource are incredibly rare. The next best are an order of magnitude more common, the next best yet another order of magnitude, and so on. Hence, on use of a resource where you have a significant margin on price (such as lithium ion batteries, where the lithium cost isn't even close to the battery cost), you don't need *any* tech advancements to remain profitable for the indefinite future. To give you an example of this occurring present-day, most reserves figures for lithium that you see don't include the Kings Valley in Nevada. The lithium there is just a little more expensive to produce than Chilean lithium, so the grand total of its value added to the "reserves" figure is a big Zero. Yet, because prices have recently gone up a bit, Western Lithium Corporation has been preparing to start mining it. In short order, a price increase of just a dollar per kilogram conservatively added *11 million tons* of lithium carbonate to world reserves from this *one deposit alone* (to put that in perspective, the largest mine in the world, run by SQM in Chile, produces ~28,000 tons a year). And, I might add, betting that mining/processing/exploration technology will cease to advance is a really, really stupid bet as well. Oh, and I didn't even cover displacement of current lithium consumption; lithium is so cheap that most of it currently goes to "low value" uses, such as greases, glazes, etc.
As for cycles, I *just discussed* how it behaves under different conditions. Pack temperature is easily controlled by a cooling system. In fact, it's actually pretty trivial with li-ion because they're so efficient; there's not much heating during charge/discharge. It is essentially impossible to discharge a BEV pack in any rate that would be seen as abusive at all. Go on -- try driving a car that has 150 miles worth of gasoline in its tank fast enough that you can drain the tank in 5-10 minutes -- I dare you ;) It's no different with a battery pack. Even if you can drain it in an hour, that's not even *close* to a serious draw on the cells. The only type of relevant abuse you can do to them is during charging, if you fast charge; however, almost nobody's going to fast charge at home, since there's no point to it; people would only fast charge on the road. So, what you're left with is:
* Discharge rates at 0.4C to 1.25C or so (gentle for LiP or the like)
* 90% of charges at ~0.25C to 0.5C or so (gentle for LiP), 10% at 3 or 4C (rough)
As independent abusive testing on RCGroups demonstrates (so that you don't have to trust company numbers), A123 cells with no climate control charged at 3-4C and discharged at 6-8C, sometimes even all the way down to 0V, lost 20% capacity in 1000 cycles. In gentle usage, that takes about 7,000 cycles. So, feel free to interpolate, but either way, you're going to get hundreds of thousands of miles on a BEV out of it. Now, *PHEV* usage is more abusive to packs**; expect PHEVs to not charge/discharge to as high rates to counter that (for example, the Volt only uses 50% of its