Electrodeposited Cu/buckypaper composites with high electrical conductivity and ampacity

Cu/buckypaper composites were prepared through electrodeposition of Cu onto buckypaper from a Cu sulfate electrolyte. The oxygen-containing functional groups were introduced to the surface of carbon nanotubes (CNTs) through acidification and oxidation. Incorporation of functional groups was shown to facilitate the spontaneous reduction of Cu ions on the surface of CNTs during immersion treatment. Under small deposition current density of 1 mA cm(-2), Cu ions could penetrate into the reticulate structure of buckypaper and nucleate homogeneously on the CNTs, which led to the formation of a thicker transition layer. Functionalization also increased the nucleation rate of Cu on the CNTs. When the current density was 1 mA cm(-2), the electrical conductivity of Cu/oxidized buckypaper composite reached the maximum value of 4.09 x 10(5) S cm(-1) which was 76% of pure Cu. The ampacities of all the composites were obviously improved compared with electrodeposited pure Cu. The Cu/oxidized buckypaper composite had the maximum ampacity of 15437 A cm(2), which was 65% and 14% higher than that of pure Cu and Cu/original buckypaper composite, respectively. Good interface bonding and reticulate structure of CNTs formed in the transition layers are responsible for the relatively high electrical conductivities and high ampacities of Cu/buckypaper composites. (C) 2017 Elsevier B.V. All rights reserved.