Researchers in South Korea have developed a carbon nanotube (CNT)-based coil that could serve as a viable alternative to copper in electric motors, marking a significant step toward lighter, more efficient, and potentially more sustainable electric drivetrain components.
The team at the Korea Institute of Science and Technology (KIST) has created what they describe as the first high-performance CNT-based coil that functions without any metal. Copper, the standard material in motor windings, offers excellent electrical conductivity but comes with notable drawbacks including weight, cost, and heat generation — issues the CNT solution aims to overcome.
While carbon nanotubes have long been explored for their promising electrical and thermal properties, their adoption has been hindered by residual metal particles that linger from the catalyst used during their synthesis, degrading performance.
KIST researchers say they have now addressed this issue through a novel cleaning method using liquid crystals. “The process naturally resolves strong aggregation during the alignment of CNTs, effectively removing metallic particles that remain on the surface,” the team stated. “Most importantly, it is able to selectively remove impurities without damaging the nanostructure of the CNTs.”
Unlike conventional liquid or gas-phase purification techniques, the new method leverages the alignment properties of liquid crystals — described as a “fourth state of matter” — to enhance purity without sacrificing structural integrity. This results in significantly improved electrical conductivity for CNT-based coils.
While a fully functional electric motor constructed entirely from CNT coils has yet to be built, researchers did demonstrate a small-scale motor capable of stable rpm control via input voltage using the new coils.
“By developing a new concept of CNT high-quality technology that has never existed before, we were able to maximize the electrical performance of CNT coils to drive electric motors without metal,” said Dr. Dae-Yoon Kim of KIST. “Based on the innovation of CNT materials, we will take the lead in localizing materials such as conductive materials for batteries, pellicles for semiconductors, and cables for robots.”
Though still in the early stages, the breakthrough points toward the potential for carbon nanotubes to one day replace copper in certain electric motor applications, with possible implications for energy efficiency, manufacturing sustainability, and the EV sector.