Integration of Continuous Graphene with Functional Metals — An Electrical Conductor at Ultrahigh Temperature

High-performance electrical conductors at higher temperatures are increasingly needed in aerospace, electric vehicles, and military applications. This study develops an innovative multilayered graphene-metal composite conductor, significantly surpassing the maximum temperature limit of conventional copper (≈90 °C for commercial wires). This approach involves integrating fine copper (Cu) wire with functional shells to exploit the high electrical conductivity and chemical inertness of silver (Ag) and graphene (G), as well as excellent anti-oxidation of nickel (Ni). Three different composite conductors, namely, NiGCu, NiAgCu, and NiAgGCu, are synthesized, characterized, and compared to quantify their overall performance and investigate the functionality of each shell. This work highlights the importance of the G layer. For example, NiAgGCu has 29.3% lower resistivity than NiAgCu, 34% lower resistivity than NiGCu, and 18.7% higher current density limit than NiAgCu after exposure to 550-850 °C. Both molecular dynamics (MD) and finite elements (FE) simulations are performed to reveal the detailed mechanisms of unprecedented thermal stability. These theoretical studies suggest that the embedded continuous graphene layer, even with its unavoidable defects, is attributed to significant performance enhancements up to 850 °C. The results present possible strategies to address current technical bottlenecks for high-performance electrical conductors in harsh environments.