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(Prof. P. Ajayan)

(Chronicle note: A pioneer in nanotechnology, Prof. Ajayan has been one of the key figures in the development of carbon nanotube technologies. He is currently the Benjamin M. and Mary Greenwood Anderson Professor of Engineering in Mechanical Engineering and Materials Science Department, Rice University, Texas.)

Prof. Ajayan can be contacted at: ajayan@rice.edu

http://www.sciencedaily.com/releases/2009/02/090209122554.htm

Nanotechnology: Lithium-Ion Batteries Have Better Performance With New Electrode Material

ScienceDaily (Feb. 9, 2009) — 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.

With 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 would also benefit, the researchers said.

The team from Pulickel Ajayan's research group published a paper this week describing the proof-of-concept research in which nanotubes are grown to look – and act – like the coaxial conducting lines used in cables. The coax tubes consist of a manganese oxide shell and a highly conductive nanotube core.

"It's a nice bit of nanoscale engineering," said Ajayan, Rice's Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science.

"We've put in two materials – the nanotube, which is highly electrically conducting and can also absorb lithium, and the manganese oxide, which has very high capacity but poor electrical conductivity," said Arava Leela Mohana Reddy, a Rice postdoc researcher. "But 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.

"Although the combination of these materials has been studied as a composite electrode by several research groups, it's the coaxial cable design of these materials that offers improved performance as electrodes for lithium batteries," said Ajayan.

"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. It is very manufacturable," Shaijumon said.

The hybrid nanocables grown in a 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 paper was written by Reddy, Shaijumon, doctoral student Sanketh Gowda and Ajayan. It appears in the online version of the American Chemical Society's Nano Letters.

The project is supported by funding from the Hartley Family Foundation.

Journal reference:

1.             Reddy et al. Coaxial MnO2/ Carbon Nanotube Array Electrodes for High-Performance Lithium Batteries. Nano Letters, 2009; 090202085144070 DOI: 10.1021/nl803081j

Adapted from materials provided by Rice University.

 

At left, a drawing shows an array of coaxial nanotubes after fabrication in an alumina template, a process developed at Rice in which the outer shell of manganese oxide is formed by vacuum infiltration, and the inner core is added through chemical vapor deposition, a standard method for building carbon nanotubes. A thin layer of gold coats the base to act as a current collector for the electrodes. (Credit: Image courtesy of Rice University)

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http://pubs.acs.org/doi/abs/10.1021/nl803081j?prevSearch=arava&searchHistoryKey=

Coaxial MnO₂/Carbon Nanotube Array Electrodes for High-Performance Lithium Batteries

Arava Leela Mohana Reddy^†, Manikoth M. Shaijumon^†, Sanketh R. Gowda^‡ and Pulickel M. Ajayan*^†

Department of Mechanical Engineering & Materials Science, and Department of Chemical & Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005

Nano Lett., Article ASAP

DOI: 10.1021/nl803081j

Publication Date (Web): February 2, 2009

Copyright © 2009 American Chemical Society

† Department of Mechanical Engineering & Materials Science.

, ‡ Department of Chemical & Biomolecular Engineering.

, * To whom correspondence should be addressed, ajayan@rice.edu.

Abstract

Coaxial manganese oxide/carbon nanotube (CNT) arrays deposited inside porous alumina templates were used as cathodes in a lithium battery. Excellent cyclic stability and capacity of MnO₂/CNT coaxial nanotube electrodes resulted from the hybrid nature of the electrodes with improved electronic conductivity and dual mechanism of lithium storage. The reversible capacity of the battery was increased by an order compared to template grown MnO₂ nanotubes, making them suitable electrodes for advanced Li ion batteries.

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http://www.dailytech.com/New+Super+Battery+Technology+Locks+Up+Energy+Behind+Bars/article14216c.htm

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http://story.birminghamstar.com/index.php/ct/9/cid/420d9e49bcaa69d0/id/464629/cs/1/

Indian American boosts lithium battery performance

Birmingham Star

Tuesday 10th February, 2009  

(IANS)

A team led by an Indian American materials scientist is working to boost lithium battery performance by creating hybrid carbon nanotubes.

Pulickel Ajayan said his team is growing nanotubes to look and act like the coaxial conducting lines used in cables. The coax tubes consist of a manganese oxide shell and a highly conductive nanotube core.

'It's a nice bit of nanoscale engineering,' said Ajayan, Rice University professor in mechanical engineering and materials science.

'We've put in two materials - the nanotube, which is highly electrically conducting and can also absorb lithium, and the manganese oxide, which has very high capacity but poor electrical conductivity,' said Arava Leela Mohana Reddy, Rice postdoctoral researcher.

'But 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.

'Although the combination of these materials has been studied as a composite electrode by several research groups, it's the coaxial cable design of these materials that offers improved performance as electrodes for lithium batteries,' said Ajayan.

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

Ajayan's early education was in Kerala, India. Till the sixth standard, he studied in a government school in Kodungallur, after which he moved to Loyola School, Thiruvananthapuram, a high school he has credited for making a strong impact on him, and for making him 'realise that learning is the most exciting thing one can ever befriend'.

He graduated from Loyola in 1977. In 1985, Ajayan graduated with a B.Tech. degree in Metallurgical Engineering from the Institute of Technology, Banaras Hindu University.

He topped his class, thereby winning the department's gold medal. In 1989, he earned a Ph. D in Materials Science and Engineering from Northwestern University, Evanston, Illinois.

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Additional links:

Bio-data of Prof. Ajayan on Rice University (Texas) website

http://www.owlnet.rice.edu/~smm5/ajayan.html

P. Ajayan in Wikipedia

http://en.wikipedia.org/wiki/Pulickel_M._Ajayan

P. Ajayan interview in Rediff.com “Nanotech holds key to the future”

http://ia.rediff.com/money/2006/dec/15inter.htm?q=bp&file=.htm

P. Ajayan news in Chronicle

http://www.itbhuglobal.org/chronicle/archives/2006/12/

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