Carbon Nanotube Coated Conductors

A novel approach based on conventional solution-coating and wire-drawing processes has been employed for the production of carbon nanotube (CNT) coated conductors. The solution process employs a mesoscopic building block, a CNT fibril dispersion formed in acid from forest-grown, long-length multiwall CNTs, to help bridge the transition from nanomaterials to thick, highly aligned technical coatings. The coatings are formed onto a roughened copper wire former through dip-coating. The roughened surface provides for mechanical attachment between the CNT coating and copper wire core that allows for the composite to be wire-drawn while wet to further shape, densify, and align the CNT coating. The wet chemistry approach offered a facile integration of different CNT and dopant types in the CNT coatings. For the specific process described here, it was observed that the CNT coatings were simultaneously doped with acid and copper nanoparticles. Coated wires were produced with conductivities on par with copper but in an engineered material that is lighter than the pure metal analogue. Dense coatings up to 90 μm in thickness were made that comprised up to 60% of the wire cross-sectional area and enabled composite densities to dip below half that of copper. The CNT coated wires had overall resistivities in the range 2.1–5 μΩ·cm, with specific conductivities relative to copper as high as 108%. The ubiquitous nature of the solution coating and conventional wire drawing processes may enable a novel approach to the light-weighting of advanced conductors for a broad range of applications.