Batteries lose weight by going viral

Commonly found in seas, soils and animal intestines, bacteriophages may someday find a home in our clothes, cell phones and laptops. Actually a type of virus, bacteriophages act like microscopic hitmen and target only certain strains of bacteria while leaving plant and animal cells, like our own, alone. Researchers from MIT report progress in harnessing bacteriophages to make better batteries.

Bacteriophages, literally "bacteria-eaters", are currently used as food additives to eliminate harmful bacteria like Listeria. Their specificity and inability to take over human cells makes them suitable for work in recombinant DNA and nanotechnology. In 2006, researchers at MIT succeeded in modifying M13 bacteriophages to produce a material capable of storing more energy than typical lithium-ion batteries. The virus created a protein that coats itself in cobalt oxide and uses carbon nanotubes to form a conductive, lightweight electrode, which is what converts chemical energy to electricity in batteries. At the 240th National Meeting of the American Chemical Society held earlier this month, researchers discussed their developments.

The new material can be manufactured at or below room temperature without the use of harmful chemicals, making it more environmentally friendly and inexpensive to produce than lithium-ion batteries. The material's flexibility also allows it to take on the shape of its container. Combined with its lightweight, rechargable qualities, it has the potential to be used in clothing for soldiers, heavy commuters and other individuals who need a portable battery supply. The virus-backed battery would also be safer to use because it operates at a lower temperature.

Currently the MIT researchers are looking into increasing the material's voltage and ability to hold a charge, which will be necessary before it can be used commercially. They aim to scale the material up for use in unmanned aerial vehicles and other military operations.

"Typical soldiers have to carry several pounds of batteries," said presenting researcher Mark Allen, Ph.D. at the meeting. "But if you could turn their clothing into a battery pack, they could drop a lot of weight. The same could be true for frequent business travellers  the road warriors  who lug around batteries and separate rechargers for laptop computers, cell phones, and other devices. They could shed some weight."