Tightly-Packed and Aligned Carbon Nanotube Fibres outperform copper

Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating.

Rice researchers broke the fibres in different conditions; air, argon, nitrogen and a vacuum, to see how well they handled high current. 

The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. 

Image courtesy Kono Lab /Rice University

On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research.

While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fibre using other technologies fail long before reaching that capacity.

But a series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper, carrying up to four times as much current as a copper wire of the same mass.

That, said the researchers, makes nanotube-based cables an ideal platform for lightweight power transmission in systems where weight is a significant factor, like aerospace applications.

Junichiro Kono

The analysis led by Rice professors Junichiro Kono and Matteo Pasquali appeared online this week in the journal Advanced Functional Materials.

Just a year ago the journal Science reported that Pasquali's lab, in collaboration with scientists at the Dutch firm Teijin Aramid, created a very strong conductive fiber out of carbon nanotubes.

Present-day transmission cables made of copper or aluminum are heavy because their low tensile strength requires steel-core reinforcement.

Scientists working with nanoscale materials have long thought there's a better way to move electricity from here to there.

Certain types of carbon nanotubes can carry far more electricity than copper.

Matteo Pasquali

The ideal cable would be made of long metallic "armchair" nanotubes that would transmit current over great distances with negligible loss, but such a cable is not feasible because it's not yet possible to manufacture pure armchairs in bulk, Pasquali said.

In the meantime, the Pasquali lab has created a method to spin fiber from a mix of nanotube types that still outperforms copper.

The cable developed by Pasquali and Teijin Aramid is strong and flexible even though at 20 microns wide, it's thinner than a human hair.

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More Information: 'High-Ampacity Power Cables of Tightly-Packed and Aligned Carbon Nanotubes' - Xuan Wang, Natnael Behabtu, Colin C. Young, Dmitri E. Tsentalovich, Matteo Pasquali, Junichiro Kono: DOI: 10.1002/adfm.201303865