Ultracapacitors Soon to Replace Many Batteries?

einhverfr writes "According to an article in the IEEE Spectrun, the synergy between batteries and capacitors — two of the sturdiest and oldest components of electrical engineering — has been growing, to the point where ultracapacitors may soon be almost as indispensable to portable electricity as batteries are now. Some researchers expect to soon create capacitors capable of storing 50% as much energy as a lithium ion battery of the same size. Such capacitors could revolutionize many areas possibly from mobile computing (no worries about battery memory), electricity-powered vehicles, and more."

Comments

Vaporware

[mark-t]

FTA

We think--and our work so far supports our theory--that by doing so, we can create a device that can hold up to 50 percent as much electrical energy as a comparably sized battery.

Why does stuff like this get so much press when it's actually nothing resembling anything that really happened?

I've got an idea!

[Anonymous Coward]

How about not writing such obscenely bloated software that it needs a mainframe-on-a-chip to show an address book?
You want to save energy? You want to reduce cost? You want to reduce carbon footprint? It's not by making yet another technology, it's by refining what we already have. We don't need Javascript code that takes seconds to execute a simple text display on a multi-GHz processor. Start there. And we won't need capacitors with the energy density of an explosive to run a freaking phone.

regenerative braking

[dltaylor]

Rapid energy storage, with very low effective series resistance, is perfect for regenerative braking, and for burst acceleration. If a vehicle starts with full batteries and capacitors, then uses the capacitors first in acceleration, they would be discharged when braking was required, allowing them to rapidly store the power from the motor/generators. The batteries (and fuel cell or combustion engine), then are sustained energy for overcoming losses, powering accessories, and long uphill grades.

Re:I doubt it will be viable in notebooks

[erayd]

But the incredibly fast charge time would be the killer app for this. Sure, it only lasts half as long, but when you can charge it in a minute or two does that really matter?

Re:Do they burst and leak fluid?

[ScrewMaster]

"What does not kill you makes you stronger". Well, that's not always true ... but if you're smart, it makes you wiser..

Re:near-instant recharge

[v1]

The "supercaps" are designed on similar principles to batteries but with a very different physical design strategy. Capacitors are built like a roll of paper towel, and have a very large surface area of contact between the plates. (several square feet for a small capacitor in a computer) This allows them to very rapidly charge and discharge because the current is distrpbuted over a large surface area. They store their energy as an electrical charge, and as you draw from it, the "pressure" lowers in relation to how much energy you have removed.

Lead acid and other chemical batteries store their energy as a changed chemical state. The chemicals build and maintain a fixed charge on the plates. This allows a 12 volt battery to hold 12 volts until it is almost discharged, unlike capacitors whose voltage drops as they are discharged. It could be quite a challenge to deal with this change in basic operation. Capacitors have another advantage in that they are able to directly produce a very high voltage, limited only by the quality of the insulating materials they are made with. Capacitors can easily hold hundreds of volts, and there are industrial caps that can hold many thousands of volts.

There's an interesting similarity for those of you familiar with paintball. Capacitors behave almost exactly like high pressure nitrogen tanks - they have very high energy and can have a very high capacity, their "pressure" drops during use, and a regulator is required to output the correct pressure. (voltage) "CA" tanks (Constant Air, CO2) on the other hand rely not on high pressure, but on a supply of liquid CO2 in the tank which changes state as gas is drawn from it, boiling to return the tank to the preset pressure. (voltage) When the supply of liquid CO2 is used, it falls just like a dead battery.

Traditional paintball guns can run on a nitrogen tank if they are equipped with a regulator to knock the pressure down to a level the gun can handle. In the same way, electrically a cap could replace a battery with not a lot of modification, but the design is very different.

Paintball air tanks are roughly the same by volume, but a modern high capacity nitrogen tank can provide more shots than a high capacity CA tank. CA tank capacity is limited by its physical size - like nitro, the more liquid (gas for nitro) you can fit into it the higher the capacity. Nitro tanks have the added advantage of the max pressure the tank can take. Stronger tanks can hold more pressure for the same size, so increases in technology allow for a greater power density in Nitro but not in CA.

I expect the same should be true of caps vs batteries - you can only put so much electrolyte in a battery. You can look for better electrolytes, but you eventually run out of better solutions. Capacitors are limited by their electrolyte and the quality of the insulators. (a bit like the ability to hold pressure in a nitro tank) Assuming technology can continue to improve on that front, capacitors may catch up with or surpass traditional batteries in power density.

I'm not counting on it though. Although capacitor technology is far from reaching its pinacale, most of the major breakthroughs have already been made. The advent of carbon fiber made Nitro tanks the better deal. Unless a new technology of the same magnitude comes up for capacitors, I don't think we'll see them in our laptops anytime soon. There's also a safety factor when you are trying to push any form of pressure really high. Nitro tanks are downright dangerous if mishandled, and must be treated carefully under the best of conditions. Jacking up the voltate on your laptop's supercap to 100kv... even if it becomes practical, I don't know if I want to carry THAT around.

Wake me when they actually achieve something.

[guidryp]

The best ultra caps are still off by an order of magnitude.

I have been hearing how eestor would have its ultra caps in cars in 2006, then 2007, and I can only assume 2008 now. Not only are they not in cars, they haven't demoed as much as a since cell. Yeah I know it is not just eestor, but I am getting tired of empty hype.

I love hearing about technology, but at some point, they get to the "put up or shut up" point. That point has past for me.

Re:Interesting - crashes?

[dgatwood]

Either that or a power cord. This would be either replacing batteries in a hybrid or in a traditional EV. Supercaps can basically solve the fundamental problem with EVs: battery life. Unlike batteries, supercapacitors don't rapidly lose their ability to take a charge over a few years. They also are more efficient, produce less waste heat, and are generally considered much safer than Lithium ion cells. These aren't jut to capture waste energy. These have the potential to store huge amounts of energy for a fairly significant period of time with relatively low leakage.

The big disadvantage is that they haven't reached the same capacity as batteries per unit of mass or volume, last I checked, and are nowhere near the density of gasoline. One big advantage, however, is that you can put them in places where you could never put batteries for thermal safety or serviceability reasons.