Sharp burnout failure observed in high current-carrying double-walled carbon nanotubefibers

Abstract

We report on the current-carrying capability and the high-current-induced thermal burnout failure modesof 5–20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improveddry-spinning method. It is found that the electrical conductivity andmaximum current-carrying capability for these DWNT fibers can reach up to5.9 × 105 S m − 1 andover 1 × 105 A cm − 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized andburnt out into cheese-like morphology when the maximum current was reached, whileDWNT fiber showed a much slower breakdown behavior due to the gradual burnout inindividual nanotubes. The electron microscopy observations further confirmed that thefailure process of DWNT fibers occurs at localized positions, and while the individualnanotubes burn they also get aligned due to local high temperature and electrostatic field.In addition a finite element model was constructed to gain better understanding of thefailure behavior of DWNT fibers.