Scale-Up Sample Fabrication and Preliminary Transport Mechanism Study of Carbon Nanotube Based Electrical Conductor

Conductive materials are indispensable for almost all aspects of life. However, conventional metal conductors have some drawbacks including heavy weight and corrosion issues. Carbon nanotubes (CNTs) are promising as an alternative conductor that offers multiple advantages and functionalities including low density, corrosion resistance, and high specific mechanical/electrical/thermal properties. Much work has been done to improve the electrical conductivity of CNT assemblies, transferring the excellent properties of CNTs demonstrate at the nanoscale to practical applications such as fiber and films remains a challenge. This research focuses on studying the improvement of electrical/mechanical performance of CNT fibers/films. . Chapter 1 gives an introduction of CNT conductors. A comprehensive literature review of CNT conductor development is presented in Chapter 2. Chapters 3, 4 and 5 discuss three projects focuses on synergistic effects, interface design and scalable fabrication, respectively. Conclusions are given in Chapter 6. We attempted to improve the electrical conductivity of CNT films based on synergistic effects though alignment and chemical doping. We fabricated large-scale continuous CNT sheets with ultra-high and stable electrical conductivity, which reached a conductivity in the range of 104 S/cm. We also investigated the interface structural optimization between CNTs and carbon matrix to simultaneously enhance strength and conductivity. To achieve this, a unique interface enhancer, pyrolyzed polydopamine (py-PDA), was added between the CNTs and carbon matrix, which resulted in better load transfer and electron transport. The as-prepared CNT/py-PDA/C composite fibers demonstrated remarkable improvements in electrical conductivity (2.1 × 103 S/cm) and tensile strength (up to 727 MPa), which should prove to be advantageous comparing to previously reported CNT/C composites. We also studied and developed a roll-to-roll production capability to fabricate continuous nanotube sheets or buckypaper with relatively high and stable conductivity. The electrical conductivity of the resultant continuous buckypaper can be improved to 7.6 × 104 S/m by using an oxidant chemical (i.e. HNO3 and I2) doping method. Those results are valuable for seeking lightweight and flexible non-metal conductors for potential engineering applications.