Wednesday, June 30, 2010

Nanotech Brings Better Batteries

Nanotech Brings Better Batteries By: Rebecca Kutzer-Rice

Researchers at MIT are using nanotechnology to build a new kind of lithium-ion battery whose charge will last much longer than the batteries of today.

Whenever I pack for a trip, I have to save room in my suitcase for a tangle of battery chargers. One for my cell phone, another for my iPod, others for my laptop and my electric toothbrush. Depending on how long I’ll be away, sometimes I stash more chargers than I do T-shirts. Researchers at MIT are using nanotechnology to develop a new breed of rechargeable battery—one whose charge will last up to 10 times longer than the batteries of today.

Most current portable devices—from MP3 players to electric lawn mowers—employ lithium-ion batteries, which emerged in the 1990s. In its basic design, a lithium-ion battery contains three basic parts: an anode (a negative electrode), a cathode (a positive electrode), and an electrolyte (a highly conductive material). To produce an electrical current and power a device, positively charged ions travel across the electrolyte to the cathode. Later, in the recharging process, the ions, now negatively charged, return to the anode.

In the new design, carbon nanotubes are added to the battery to replace the anode and the cathode. The nanotubes self-assemble into a stiff but porous substance that contains many oxygen molecules, which are able to store large numbers of lithium ions. This unique design allows the structure to serve as both the positive and the negative electrode in the battery.

This diagram illustrates how lithium ions bond to the oxygen ions on a carbon nanotube, ultimately creating a higher-power battery (Source: Yang Shao-Horn, MIT).

The insertion of carbon nanotubes promises great improvements for traditional lithium-ion batteries. In addition to providing much higher energy output, the new batteries also show improved stability over time. After being charged and discharged 1,000 times—a test that would weaken a traditional battery—the carbon-nanotube batteries showed no signs of decreased performance.

The current device would be suitable for portable devices, like iPods and cell phones. The scientists envision that that a higher capacity version could have larger uses, such as in hybrid cars.

While I won’t be leaving my battery chargers at home just yet, carbon-nanotube batteries could mean more room in my suitcase on future trips, when my devices will keep their charges for plenty of time.

Findings were published in Nature Nanotechnology. Researchers from MIT included Yang Shao-Horn, Paula Hammond, Seung Woo, Naoaki Yabuuchi, and Betar Gallant.

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