Lightweight Cable Made of Braided Nanotubes Could Replace Copper Wires

Nanocable

A power cable made entirely of iodine-doped double-walled carbon nanotubes is just as efficient as traditional power cables at a sixth the weight of copper and silver.Yao Zhao/Rice University

Cables made out of nanowires could be just as efficient as the copper cables we've been using for more than a century, but at a fraction of the weight, according to a new paper. Braiding billions of carbon nanotubes into a nanowire cable can efficiently replace copper in a light bulb circuit.

Traditional cables are made by braiding or twisting together two or more wires or optical fibers, usually metal or silicon, to carry a current or signal. In a new study, Rice University researchers instead used double-walled carbon nanotubes, made of concentric rolled-up sheets of graphene.

To make the cable, the team grew billions of nanotubes and spun them with a polymer into tiny wires just a few centimeters long. The wires were doped with iodine to keep them stable, and then they could be tied together without compromising their conductivity, according to a Rice news release. The resulting cable is corrosion-resistant and is much lighter and less dense than copper. Its conductivity-to-weight ratio, known as specific conductivity, is better than copper and silver — it's second only to sodium in the suite of metals with the highest specific conductivity, the researchers say.

To prove it worked, Rice doctoral student Yao Zhao built a circuit that directed power through the nanocable, replacing copper wire. He turned on a CFL bulb and let it shine for several days, and saw no signs of degradation in the nanocable. Tests showed it would be just as strong and durable as copper, and would work in a wide range of temperatures, the team says.

The next step is to make longer, thicker cables that can carry a greater current, according to Enrique Barrera, a Rice professor of mechanical engineering and materials science. The nanocables could someday be used in aircraft, spacecraft and cars, and could someday even replace electrical wiring in homes, the team says. Barrera and Zhao explain the technique in the video below.

The work appears in the journal Nature Scientific Reports.

[via PhysOrg]