Fabrication of High Specific Electrical Conductivity and High Ampacity Carbon Nanotube/Copper Composite Wires

Abstract

A challenge is to integrate Cu with carbon nanotubes (CNTs) and form a free-standing composite wire. This is achieved by first making a CNT filament using high concentration (20 g L−1) CNT dispersion, an acid-free wet spinning process and then by replacing the polymer with copper using heat based polymer decomposition and periodic pulse reverse electroplating. It is demonstrated that indeed the specific conductivity and the current-carrying capability (or ampacity) are increased manifold. The multiwalled CNT (MWCNT)/Cu composite wires developed in this paper have electrical conductivity σ ≈ 5.5 × 10 5 S cm−1. These MWCNT/Cu wires are 2/3rd the weight of bulk Cu wires. Their specific electrical conductivity is σρ ≈ 9.38 ×10 4 S cm2g−1 which is 45% higher than International Annealed Copper Standard Cu. These composite wires have an ampacity of A ≈ 20 × 105 and 4 × 105 A cm−2 for 1.5 and 17 mm gauge length wires, respectively, which is four to six times higher than pure Cu depending on the wire lengths. MWCNTs volume percentage in the MWCNT/Cu wire is about 40%.