The high current-carrying capacity of various carbon nanotube-based buckypapers

Buckypapers (BPs) are thin films made up of carbon nanomaterials, such as single-walled carbon nanotubes (SWCNTs) or mixtures of SWCNTs with multi-walled carbon nanotubes (MWCNTs) or vapor-grown carbon nanofibers (VGCNFs). In this research, BPs were exposed to high electrical current densities under different environments, and the effects on nanotube and BP breakdown were observed. In ambient conditions, SWCNT BP breakdown happened at around 430 deg. C with a flash of light. Mixed BPs of SWCNTs/MWCNTs and SWCNTs/VGCNFs showed higher ignition temperatures of over 500 deg. C. The results were compared to those from thermogravimetric analysis. In a vacuum, current-driven thermal heating from the samples can generate temperatures greater than 2000 deg. C. The breakdown current density increased to more than three times that in open air. The breakdown current density of a BP sample increased proportionally to its conductivity. A finite-element model based on Joule heating and heat convection was used to explain this relationship. Further experiments also proved that the high current-carrying capacity of microscale nanotube array samples improved to 106 A cm-2 due to increased heat dissipation through the substrate