“This is the first time that researchers have produced results with CNT fibers demonstrating sufficient performance in this regard to offer a realistic industrial alternative to traditional conductive materials,” says Juan José Vilatela, Ph.D., head of the multifunctional nanocomposites group at IMDEA. He worked on the R&D project along with scientists at the Technical University of Madrid and the University of Zaragoza.

Vilatela and his colleagues were able to produce gas-phase intercalated CNT fibers with room-temperature conductivity as high as 24.5 MS/m (MegaSiemens per meter), nearly half that of copper, but six times lighter.

“Given this substantial weight advantage, these results demonstrate electrical conductors that combine not only a significantly improved weight-to-performance ratio, but also absolute conductivity levels that meet industrial requirements,” explains Vilatela.

According to Vilatela, tetrachloroaluminate (AlCl4) was used as a dopant. By retaining the original structure of the CNT bundles, the doping process increases conductivity while preserving their exceptional mechanical properties.

By doping the highly aligned CNT fibers with AlCl4, the engineers were able to achieve a more than 17-fold increase in electrical conductivity. “This resulted in a mean specific conductivity in excess of that of copper, with a highest measured value above that of aluminum,” claims Vilatela.

“This is particularly significant for the electrification of transport, be it EVs, drones or aircraft, which require large numbers of conductors at the lowest possible weight,” adds Vilatela. “It also holds promise for overhead power cables, which are often limited by their own weight.”