Effect of Applied Pressure on the Electrical Resistance of Carbon Nanotube Fibers

Abstract

Carbon nanotubes (CNTs) can be spun into fibers as potential lightweight replacements for copper in electrical current transmission since lightweight CNT fibers weigh <1/6th that of an equivalently dimensioned copper wire. Experimentally, it has been shown that the electrical resistance of CNT fibers increases with longitudinal strain; however, although fibers may be under radial strain when they are compressed during crimping at contacts for use in electrical current transport, there has been no study of this relationship. Herein, we apply radial stress at the contact to a CNT fiber on both the nano- and macro-scale and measure the changes in fiber and contact resistance. We observed an increase in resistance with increasing pressure on the nanoscale as well as initially on the macro scale, which we attribute to the decreasing of axial CNT…CNT contacts. On the macro scale, the resistance then decreases with increased pressure, which we attribute to improved radial contact due to the closing of voids within the fiber bundle. X-ray photoelectron spectroscopy (XPS) and UV photoelectron spectroscopy (UPS) show that applied pressure on the fiber can damage the π–π bonding, which could also contribute to the increased resistance. As such, care must be taken when applying radial strain on CNT fibers in applications, including crimping for electrical contacts, lest they operate in an unfavorable regime with worse electrical performance.

From Waste Plastics to Carbon Nanotube Audio Cables

“…CNT-based cables show plenty of promise with individual CNT electrical conductivity besting copper, while also having the benefit of lower mass density, owing to the hollow cylindrical nature of the nanotubes [6]. Despite there being several different attempts at making long cables out of individual CNTs [7][8][9][10][11][12][13], the primary issue remains that the starting material with the CNTs is generally a mixed bag when it comes to both the general purity being questionable-owing to the presence of contaminants, such as residual catalyst and amorphous carbon-as well as containing a mix of single-and multi-walled CNTs of different chiralities [14,15] to where there is a sliding scale of metallic to semiconducting CNTs in use.…”

Upcycling of face masks to application-rich multi- and single-walled carbon nanotubes

“…Electrical testing was done in air, meaning there was already a limit present on how much voltage could be run through the make-shift CNT-based conductor before amorphous carbon and/or CNTs oxidized, and the conduction pathway disrupted [32]. Figure 6 shows a multi-stage decrease in electrical resistance with applied voltage, which acts analogous to the voltage annealing of CNT fibres previously reported [33] with the removal of surface contaminants and amorphous carbon first before irreversible damage to the CNTs just past 3.5 V. A sealed conductor composed of aligned and purified CNTs [33,34] should be able to withstand more and have a lower electrical resistance as well, but the goal here is to show these are CNTs that were manufactured from face mask materials and are electrically conductive.…”

Increased Electrical Conductivity of Carbon Nanotube Fibers by Thermal and Voltage Annealing

“…Depending on the manufacturing process, this can be a bulk phenomenon or one with a substantial surface-only effect. CNT fibers, when used for electrical transmission, can have different conduction pathways depending on the paths of least available resistance, and the point of contact at the surface of the fibers is a critical step to be accounted for [12][13][14].…”