Rice University
Rice Magazine| The Magazine of Rice University | No. 3 | 2009
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Batteries Get a Boost

Need to store electricity more efficiently? Put it behind bars.

That’s essentially the finding of a team of Rice University researchers who have created hybrid carbon-nanotube/metal-oxide arrays as electrode material that may improve the performance of lithium-ion batteries.

Ajayan and GowdaWith battery technology high on the list of priorities in a world demanding electric cars and gadgets that last longer between charges, such innovations are key to the future. Electrochemical capacitors and fuel cells also would benefit.

The Rice research team, led by Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and professor of chemistry, is growing nanotubes that look — and act — like the coaxial conducting lines used in cables. The coaxial tubes consist of a manganese oxide shell and a highly conductive nanotube core.

“The nanotube is highly electrically conducting and also can absorb lithium, and the manganese oxide has very high capacity but poor electrical conductivity,” said Arava Leela Mohana Reddy, a Rice postdoctoral research associate. “When you combine them, you get something interesting.”

That would be the ability to hold a lot of juice and transmit it efficiently. The researchers expect the number of charge/discharge cycles such batteries can handle will be greatly enhanced, even with a larger capacity.

“At this point, we’re trying to engineer and modify the structures to get the best performance,” said Manikoth Shaijumon, also a Rice postdoc. The microscopic nanotubes, only a few nanometers across, can be bundled into any number of configurations. Future batteries may be thin and flexible. “And the whole idea can be transferred to a large scale as well,” Shaijumon said. “It is very manufacturable.”

The hybrid nanocables grown in the Rice-developed process could also eliminate the need for binders — materials used in current batteries that hold the elements together but hinder their conductivity.

The project is supported by funding from the Hartley Family Foundation, and the findings appear in a paper written by Reddy, Shaijumon, doctoral student Sanketh Gowda and Ajayan in the online version of the American Chemical Society’s Nano Letters.