[LINK] 'Greener' Batteries

[stephen at melbpc.org.au]

Viruses Used to Grow "Greener" Batteries

Charles Q. Choi for National Geographic News, April 3, 2009 
http://news.nationalgeographic.com/news/2009/04/090403-virus-battery.html


With the help of a common virus, scientists have built a battery that 
rivals the state-of-the-art rechargeable models now powering personal 
electronics and hybrid vehicles. 

The hope is to replace the costly, toxic electrodes currently used in 
lithium-ion batteries. 

The researchers modified the M13 virus, which infects only bacteria, to 
grow proteins on its surface that attract amorphous iron phosphate. 

The result: Wires just nanometers thick of the material, which is cheaper 
and environmentally friendlier than ones currently used to make 
electrodes for lithium-ion batteries. 

The scientists also programmed the virus so that one end became sticky to 
carbon nanotubes, which are extraordinarily good conductors of 
electricity. 

Electrons easily travel along the carbon nanotubes to the amorphous iron 
phosphate networks, transferring energy in a very short time. 

Using these ingredients, the researchers devised coin-sized batteries 
comparable in performance to commercial lithium-ion batteries. 

"The more genetic engineering we did, the better it got," said researcher 
Angela Belcher, a materials scientist at the Massachusetts Institute of 
Technology. 

Carbon nanotubes are still expensive, and researchers debate what risks 
they might pose to the environment. If the nanotubes become a barrier, 
the same process could be performed with other good electrical conductors 
such as silver or gold, Belcher said. 

While her team is still in the early stages of its work, Belcher thinks 
the project could soon get "twice the power performance of what we 
demonstrated with this proof of principle here." 

Findings detailed online in the April 2 issue of the journal 'Science' 

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Cheers,
Stephen