The Nanobattery has Arrived

Battery driven cars may now have faster pick-up

Lithium ion batteries are popular in consumer electronics. With maximum energy capacity and slow loss of charge when not in use, they figure in battery driven cars too. But there is a drawback. When in use, lithium (Li) ions take a long time to move through the electrolyte between the cathode and the anode. This generates electric current slowly giving the cars a bad pick-up.

Many companies are researching new materials for the battery that would shorten the diffusion distance (distance travelled by Li ions between the cathode and the anode). This in turn would generate electric current rapidly.

In 2005, Toshiba announced a new Li ion battery with a nanostructured lattice that focused on rapid recharge of the battery. But electricity generation was still slow.

A team of researchers from the Indian Institute of Sciences, Bengalooru and the University of Namur, Belgium, came up with the idea of a battery made of carbon nanotubes with lithium cobalt oxide.

The team prepared a compound using lithium hydroxide, ethyl alcohol, a cobalt-based complex organic compound and triethanolamine as raw materials. This was heated at 700°C. The researchers expected the reaction to generate carbon nanotubes with lithium cobalt oxide but what they found was even better - metallic lithium encapsulated in carbon nanotubes.

"The samples sent to the University of Namur were analyzed by Carla Bittencourt, the second author of the paper. She confirmed lithium's presence in the carbon nanotubes," said Mahua Das, the lead author. The study was published in Applied Organometallic Chemistry, Vol 22. Directly heating Li with carbon nanotubes is not an option as it easily forms oxides and nitrides with atmospheric oxygen and nitrogen.

Carbon nanotubes, encapsulating metallic lithium, potentially acts as a nanobattery where metallic lithium acts as the cathode and carbon nanotubes, as the anode. "Since the diffusion distance is just a few nanometres, the diffusion time also is a few nanoseconds," said Das. Such a battery could find its use in the next generation communication and remote sensing devices.

Source

Down To Earth, January 2009