Scientists use viruses to make miniature rechargeable batteries

April 9th, 2009 - 4:24 pm ICT by ANI  

London, April 9 (ANI): Scientists have used genetically engineered viruses that assemble into electrodes to make complete miniature rechargeable batteries for the first time, which could improve the performance of hybrid electric cars and electronic gadgets.

According to a report in New Scientist, the new lithium ion batteries are as powerful as existing devices but smaller and cleaner to make, claim the team behind the work.

Lithium ion batteries exploit the reactivity of lithium to produce a current. Inside the battery, lithium ions move from the anode to the cathode, forcing electrons in the opposite direction around an external circuit.

This process is reversed when the battery is recharged.

Making these batteries takes a tough manufacturing process because of the highly reactive components, aggressive solvents and high temperatures used in construction, as well as the dangers of handling lithium.

Viruses could make this process much safer and cleaner, according to Angela Belcher at the Massachusetts Institute of Technology (MIT).

Her team converted a harmless virus called M13 into a cathode by inserting a gene that causes the virus to produce proteins that bond with iron and phosphate ions in a surrounding solution.

As a result, the long, tubular virus particles become sheathed in an “armour plating” of iron phosphate, turning them into nanowires.

The resultant batteries were not as good as commercial models, however, the cathodes turned out to be good at conducting lithium ions but not electrons.

To solve this, the team inserted a second gene that creates a protein at the tip of the virus that bonds to a carbon nanotube.

The nanotube increases the electron conductivity of the combined structure.

“We were basically adding a highway that allows the electrons to move in and out rapidly,” said Belcher.

The resulting battery turned out to be as good as the best commercially available that use crystalline lithium iron phosphate materials.

Since the team had previously used the same viral technique to produce anodes, it has now been able to make a full virus-based 3-volt lithium ion battery.

Compared to conventional lithium ion batteries, the biologically grown battery is environmentally friendly because much of the materials can now be made at room temperature or on ice and without harsh solvents.

“It’s a pretty simple process that doesn’t require fancy equipment,” said Belcher. (ANI)

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