Highly Conductive and Lightweight Carbon Nanotube Conductor and Scalable Manufacturing for Conductive Fiber-reinforced Composite Application

Abstract

Conductive metals such as copper are heavily used as conductors or lightning protection materials in aircrafts and other industrial areas. But the high bulk density and corrosion problem make non-metal conductors with low density and corrosionresistance more promising such as carbon nanotubes (CNTs). However, the small sample size of previously reported highly conductive CNT fibers (1-2 μm in diameter) or films (less than 1 μm in thickness) limits the practical engineering applications. In this work, a macroscopic continuously stretched CNT tape was prepared with excellent CNT alignment, high conductivity, and large dimensional size (~ 9 mm in width and ~ 30 μm in thickness). Through combined post-treatments of mechanical stretching, iodine doping and polymer capping layer, the macroscopic CNT tape shows high conductivity in the range of 10,000 S/cm (the highest is ~ 13,000 S/cm) and this excellent performance is stable in open air without any sign of degradation. Various characterizations were conducted including SEM observation, Raman, TGA, PPMS, electrical, and mechanical measurements. Overall, the high conductivity was ascribed to better CNT alignment after stretching and high carrier density after iodine doping. More importantly, the substantial stability of electrical property was demonstrated, benefitting from the polymer capping layer. Additionally, this process is based on commercially available raw materials and scalable for industrial production. And the proposed method here can be readily transferred to our buckypaper (CNT sheets) with roll-to-roll production capability. Furthermore, these highly conductive CNT tape and sheet can be directly incorporated into fiber-reinforced composite to improve the conductivity which could serve multiple functionalities as structural, electromagnetic interference shielding and lightning protection materials in aircrafts. This work opens a new path to optimize the electrical performance of CNT assemblies with a wide range of engineering applications including conductive composites..