It keeps going and going and going...

That's the promise of a new battery developed by researchers at MIT's Laboratory for Electromagnetic and Electronic Systems. They're using nanotechnology to improve an energy storage device called an ultracapacitor.

Nanotubes: (Photo courtesy Riccardo Signorelli, Laboratory for Electromagnetic and Electrical Studies, MIT)

Unlike regular batteries, which can generate electricity from a chemical reaction, capacitors store energy as an electrical field. Ultracapacitors can store lots of energy for a long time, but they need to be much bigger than regular batteries to hold the same amount of electricity. The new MIT technique, uses nanotechnology to improve the storage capacity of existing capacitors and may eventually help to make them smaller.

How does it work?

A battery has two electrodes, or terminals, one positive and one negative. Inside the battery are chemicals that react with each other to produce electrons. The electrons collect on the negative terminal of the battery. When you connect the terminals with a wire, you can use the flow of electrons to power things. A capacitor also has two electrodes-metal plates separated by a material that doesn't conduct electricity. A positive charge builds up on one plate, and a negative charge builds up on the other. When you connect the two electrodes, they discharge their energy. A battery can actually "create" energy by changing chemicals into electricity while a capacitor can only store energy it has been charged with.

Ultracapacitor in a hybrid engine: An ultracapacitor in a hybrid gas/electric engine for a car.

Today's ultracapacitors use electrodes made of activated carbon; the carbon is porous, so it has lots of surface area for the electrons to build up on. But the pores are irregular in size and shape, which reduces efficiency. That's why capacitors have to be big. But the MIT ultracapacitor has electrodes of vertically aligned carbon nanotubes, each one thirty-thousandth the width of a human hair. The regular shape and alignment of the nanotubes greatly increases the surface area, making the ultracapacitor very efficient at storing electrons.

Carbon nanotubes: Vertically aligned carbon nanotubes have lots of surface area to store electrons. (Photo courtesy Riccardo Signorelli, Laboratory for Electromagnetic and Electrical Systems, MIT)

Smaller is better

Ultracapacitors are long lasting and quick-charging. Storing energy at the atomic level with nanotubes means that they can finally be small, too, perhaps eventually powering everything from flashlights and cell phones to hybrid cars and missile-guidance systems.

Make it at the Museum

Stop by the Museum on Saturday, February 18th. You can make a pop can flashlight and test some conventional batteries. Experiment with electricity, circuits, and capacitors more at the AC/DC electricity bench in the Experiment Gallery.

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

Thanx for this nice piece of information. Can we use these "Ultra capacitors" to store renewable energy from WIND? :)


posted on Thu, 04/06/2006 - 2:25am
Liza's picture
Liza says:

Sharon Hartshorn, Gallery Supervisor for the Experiment Gallery, read the above post and then sent me a message:

"I wonder if you don't want to include something about how much of a difference in size this can make. Maybe when you say 'That's why they have to be so big' you could add something like 'up to 25 times bigger than a conventional battery.'

And/or when talking about the difference and consequent advantage of an ultracapacitor over a conventional battery, perhaps you could say something about how the chemical reaction in a conventional battery continues even when it is on the shelf - limited shelf-life. Capacitors have a longer shelf life. And they can discharge their stored energy more completely."

Thanks, Shari.

posted on Thu, 02/16/2006 - 4:00pm
Liza's picture
Liza says:
nanotubes2(Photo courtesy Riccardo Signorelli, Laboratory for Electromagnetic and Electronic Systems, MIT)
nanotubes4(Photo courtesy Riccardo Signorelli, Laboratory for Electromagnetic and Electrical Systems, MIT)

I also wrote to Riccardo Signorelli, one of the researchers on the ultracapacitor project. All the press releases I read talked about how the new ultracapacitors might eventually replace conventional batteries. But I thought capacitors discharged all their energy in a quick, massive burst. (That's why they're used in, say, hybrid vehicles: you get a power boost when you need to accelerate or go up a hill, and the battery recharges quickly so it's ready again when you need it.) I couldn't understand why you'd want to power a cell phone or a flashlight with an ultracapacitor instead of a regular battery.

Signorelli wrote me back:

"The length of the discharge depends on how much
energy you have and how much energy per second you withdraw (power).

If you have an ultracapacitor device (I am not saying we have it today) that can store an energy up to the same energy of a battery, then you can discharge this energy either in a quick burst or over a longer time."

He also sent me some cool pictures. (Remember: each of these nanotubes is one thirty-thousandth the width of a human hair!)

posted on Thu, 02/16/2006 - 4:32pm
Anonymous's picture
Anonymous says:

is anyone using this storage method in conjunction with solar energy production and is this a rechargeable system

posted on Fri, 03/10/2006 - 4:03pm
bryan kennedy's picture

Well as far as I know this technique wouldn't work well specifically for solar cells. But there are scientists working on solar cell technology using nano wires. Local scientists at the U of M lead by Eray Aydil are doing just that by dipping sheets of nano wires in dyes to make them turn solar energy into electricity at low cost.

posted on Fri, 03/10/2006 - 4:26pm
bryan kennedy's picture

Another group of scientists has created a unique capacitor using nanotechnology. The group at the John Innes Centre used a virus to infect a controlled group of black eyed pea plants in the lab. Iron compounds were linked to the virus which allowed them to build this electronic structure that would store some electricity--a capacitor.

posted on Sun, 03/19/2006 - 10:37am
ARTiFactor's picture
ARTiFactor says:

I noticed a recent burst of media coverage about capacitor batteries which use carbon nanotubes. ScienceCentralNews references an article in DISCOVER Vol. 27 No. 05 | May 2006 | which says a prototype is only months away but that we may not see these quick recharge, last almost forever batteries for sale until 2011.

posted on Fri, 06/09/2006 - 10:16am
Bud Fisher's picture
Bud Fisher says:

I have a question and didn't know who to pose it to, so I'll ask you. Can the rotation of the wheels of a car produce it's own electricity? Sort of like a turbin at a power plant.


Bud Fisher

posted on Sun, 04/22/2007 - 1:43pm
cowbot's picture
cowbot says:

Since your question wasn't answered yet...

The rotating wheels on a car can be turned into energy. This is what some trains and hybrid electric cars do in order to brake -- they turn the mechanical energy of the moving vehicle into electricity, thus slowing it down. The same thing happens when you use a generator on a bicycle to power your lights.

The important thing to remember is conservation of energy; there is no free lunch. Transforming mechanical energy into electricity with a generator creates electromotive resistance, which acts as a brake.

posted on Sun, 07/15/2007 - 9:40am
Gene's picture
Gene says:

Popular Mechanics takes a look at plug-in hybrid cars.

posted on Fri, 04/27/2007 - 10:10am
batteries are cool's picture
batteries are cool says:

what companies slogan is "It just keeps going, and going, and going"??

posted on Thu, 05/31/2007 - 11:41am
Leana Medicine Crow's picture
Leana Medicine Crow says:

its interesting i guess

posted on Sun, 07/15/2007 - 12:52pm
JimJohnson's picture
JimJohnson says:

Here is a site about the ultracapacitors: http://www.ultracapacitors.org



posted on Tue, 01/29/2008 - 2:30pm
Richard's picture
Richard says:

That's amazing. That battery combined with new LCD and LED technology would really save energy. You could run an LED Flashlight almost indefinitely.

posted on Thu, 04/08/2010 - 1:07pm

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