KIST
Researchers from the Korea Institute of Science and Technology (KIST) have developed the world’s first full-fledged electric motor with no metal elements in its design.
It is noted that the developers replaced copper coils with carbon nanotubes. The electric motor they created demonstrated 133% better electrical conductivity and was 80% lighter than traditional designs.
«Whether it’s electric cars, drones or spaceships, a common technical challenge for future transportation is lightweighting. Reducing the weight of a vehicle not only reduces energy consumption, but also improves battery efficiency and increases the range of flight», — the researchers say.
According to Dr De-Young Kim, a new technology using carbon nanotubes maximizes the electrical characteristics for controlling metal-free electric motors.
«These one-dimensional tubular nanomaterials with carbon atoms arranged in a hexagonal honeycomb structure, which are known to be much lighter than conventional metals, but at the same time have excellent electrical conductivity, mechanical strength, and thermal conductivity», — the developers add.
The development was made possible by a new purification method required to replace copper coils with carbon nanotubes. Using a purification method called LAST (Lyotropic Liquid Crystal-Assisted Surface Texturing), the researchers removed metal impurities that have historically affected nanotube technology while preserving electrical properties.
Electric motor coils motors are usually made of copper because of its high electrical conductivity. However, copper has a density of 8.9 grams per cubic centimeter, which makes the overall weight of the motor significant. Carbon nanotubes have similar electrical conductivity and a density of only 1.7 grams per cubic centimeter. This reduces the weight of the motor by 80%.
The key problem was contamination. During production, particles of the metal catalyst get into the nanotubes, degrading the electrical characteristics. By dissolving the nanotubes in chlorosulfonic acid, the researchers created a liquid crystal state in which the tubes self-align. When exposed to water, this solution generates hydrochloric acid, which removes impurities from the iron catalyst, leaving the carbon nanotube structures pure. This process reduced metal contamination from the initial 12.7% to less than 0.8%.
The purified carbon nanotubes demonstrated an electrical conductivity of 7.7 megasamples per meter. When integrated into a motor, the specific rotational speed — a measure of performance per unit weight — was 1.06 times lower than that of an equivalent copper-based motor. The motor also ran continuously for 60 minutes under various power loads.
The researchers built a model of a car running on this engine. According to the simulation results, the car drove 10 meters in 25 seconds on an asphalt road.
Source: Interesting Engineering