Carbon Nanotube Fibers Perform Better than Copper in Electrical Current Transmission
20 February 2014
Researchers at Rice University have developed carbon nanotube-based fibers that outperform copper cables of the same weight in terms of electrical current transmission on a pound-per-pound basis, the university says on its website.
Individual nanotubes have the capacity to carry almost 1,000 times more current than copper, but if the same tubes are combined into a fiber using other technology they prove ineffective long before reaching that capacity. However, wet-spun carbon nanotube fiber still performs better than copper, showing the ability to transmit up to four times as much current as a copper wire of the same mass, tests carried out by Rice scientists confirmed. The successful experiment puts nanotube-based cables well on the path to becoming an ideal lightweight power transmission platform in aerospace applications and other systems where mass is of substantial importance.
Conventional transmission cables made of copper or aluminum are weighty due to their low tensile strength that needs to be reinforced with a steel core and many scientists have explored ways to transmit electricity using nanoscale materials. The Rice team, led by professors Junichiro Kono and Matteo Pasquali, believe that the ideal cable would be made of long metallic "armchair" nanotubes that would carry current over long distances with nominal loss, although such a cable is not a feasible option since the production of pure armchairs in bulk is yet to become possible, according to Pasquali. The team, meanwhile, was successful in finding a method to spin fiber from a mix of nanotube types that still perform better than copper, developing a strong and flexible cable with a width of 20 microns, or less than that of a human hair.
The researchers also analyzed the "current carrying capacity" (CCC), or ampacity, of the fiber, establishing that it is the highest ever reported for any carbon-based fiber, Kono commented.