On the resistivity, temperature coefficient of resistance, and ampacity of Cu–CNT and Ni–CNT composites

Abstract

Cu–CNT composites are promising candidates to overcome the maximum current capacity limitation of most conductive materials. Yet, the ampacity gains reported in the literature are controversial, and the key to efficient Cu–CNT composites is not established. In this regard, the choice of the right type of CNT is instrumental. The use of Ni as interface is being increasingly investigated to enhance the electron transfer between Cu and the CNT. Here, Cu–CNT and Ni–CNT composites integrating MWCNT (ø = 80–90 nm – L = 800 μm) are investigated. This work presents a novel electroplating method to fabricate Cu/Ni–CNT composites with high degree of metal filling and high CNT vol% (∼42–43%). The resistivities of the Cu–CNT and Ni–CNT composites are 4.32 × 10⁻⁶ and 4.44 × 10⁻⁵ Ω cm, respectively. The annealing of the Cu–CNT composite is detrimental to its resistivity while it is beneficial for the Ni–CNT composite. The TCR of the composites suggests that the CNT–metal electron transfer is promoted by Ni. The metal–CNT composites display lower ampacities than pure metals. The importance of controlling the experimental parameters and the system architecture is instrumental to investigating the figure of merit of high ampacity materials. A lack of standardized experimental procedures may lead to biased conclusions as reported today in the literature.