Enhancing the Electrical Properties and Surface Uniformity of a Copper-Coated Carbon Nanotube Fiber by Optimizing Copper Electrodeposition

Abstract

Lightweight, high-strength electrically conductive materials are critical in satisfying the demands of future mobility solutions; carbon nanotubes (CNTs), which possess low densities, exceptional mechanical strength, and superior electrical properties, may be promising candidates. However, when CNTs are assembled into macroscopic fibers for practical application, their electrical conductivity deteriorates significantly owing to inter-tube contact resistances, limiting their effectiveness as conductors. In this study, we developed a Cu-coated CNT (Cu-CNT) hybrid conductor by electrodepositing on direct -spun CNT fiber to address this challenge. A smooth, pore-free Cu-CNT fiber was cost-effectively fabricated by optimizing the electroplating conditions (e.g., the applied potential and charge density) and bath composition (e.g., incorporating various suppressors, accelerators, and levelers). The resulting Cu-CNT hybrid fiber exhibited an excellent electrical conductivity (2.34 × 10⁷ S/m), reaching approximately 50% of that of pure Cu (5.8 × 10⁷ S/m). Additionally, the Cu-CNT fiber demonstrated a specific electrical conductivity of 4189 Sm²/kg, which was approximately 62.6% of that of pure Cu (6614 Sm²/kg). Therefore, the electrodeposited Cu-CNT fiber effectively overcomes the limitations of direct- spun CNT fibers, offering a viable pathway toward next-generation lightweight electrical conductors that combine the mechanical advantages of CNTs with the electrical performance of Cu.