Interface engineering for high-strength and high-ampacity of carbon nanotube/copper composite wires

Demands for lightweight and high strength electrical power transmission wires continue to rise, especially for electric vehicles, aerospace and 5G communication applications. Carbon nanotubes/copper composite wire is regarded as one of the promising candidate material systems for transmitting electricity and thermal energy. However, the improvements of the electrical conductivity and ampacity of CNT/Cu composite fiber often sacrifices the strength heavily. In this paper, a facile and robust approach including densification and Ni discontinuous nanoparticle layer (NiDPL) pre-seeding prior to Cu electroplating, was developed to enhance simultaneously the strength and ampacity of CNT/Cu composite fiber. Benefiting from the densification process, the conductivity and strength of CNT fiber were improved greatly. Further, NiDPL seeds formed using organic Ni salt (such as nickel acetate) were served as active sites for subsequent Cu layer deposition. The NiDPL were constructed on the surface of CNT fiber to improve both the chemical affinity and the electrons transfer between CNT and Cu. Finally, CNT/Cu composite wire with NiDPL achieved both high strength (2.54 GPa) and ampacity (1.68 × 106 A/cm2).