Core-sheath composite electric cables with highly conductive self-assembled carbon nanotube wires and flexible macroscale insulating polymers for lightweight, metal-free motors

Recent advancements in the development of lightweight conductors through the self-assembly of nanomaterials at the macroscopic scale have garnered significant attention for electrical wiring applications where weight reduction is critical, such as in the automotive and aerospace industries. In this study, we successfully demonstrate a metal-free motor constructed with a core-sheath composite electric cable (CSCEC), utilizing continuous carbon nanotube (CNT) wires and flexible macroscale insulating polymers. The electrical performance of these metal-free motors is significantly enhanced by incorporating a lyotropic liquid crystal (LLC)-assisted surface texturing (LAST) process. This process enables individual CNT dispersion through surface protonation at the primary level, effectively removing metal catalyst particles while preserving the intrinsic one-dimensional (1D) nanostructures crucial to their physical properties. Combined with the low density of CSCEC, the substantial increase in electrical conductivity achieved through compact packing and uniaxial orientation allows the specific rotational velocity of the metal-free motors to be comparable to that of copper (Cu)-based electrical conductors at the same applied voltages. Finally, we successfully powered a scale model car using a metal-free motor made from high-performance CSCECs, underscoring their potential as a sustainable, lightweight alternative to conventional metal-based wiring, advancing next-generation energy systems, and contributing to CO2 emission reduction. Boosting the electrical performance of self-assembled carbon nanotube wires through a lyotropic liquid crystal-assisted surface texturing process enables core-sheath composite electric cables toward lightweight, metal-free motor applications.