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."

Comments

EEStor

[paul248]

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?

Re:EEStor

[smilindog2000]

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: 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 ?

[Genda]

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:How?

[Ihlosi]

So why not just use toilet roll as a capacitor?

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:Here's the deal

[pradeepsekar]

In microbiology, while trying to grow bacterial cultures, there is something called as the limiting resource - sometime the Glucose added to the culture, sometimes the nitrogen-nutrient added. And the culture grows till that nutrient is exhausted. Or it has exhausted the ability to dispose waste. Some nutrients remain unused, unless the mixture was so precisely balanced at the beginning.

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).

Or until we invent...

[clonan]

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:Or until we invent...

[Rei]

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:advantages of batteries

[loshwomp]

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.