Korea Institute of Science and Technology replaces classic windings with metal-free wires

Dae-Yoon Kim and his team at the Composite Materials Research Institute of the Korea Institute of Science and Technology (https://www.kist.re.kr/eng/index.do) (KIST) have developed a lightweight replacement for copper cables in electric motors. Carbon nanotubes (CNTs) are used, which are arranged in myriad rows.

Only 0.3 millimetres thick

Using a process called ‘lyotropic liquid crystal-assisted surface texturing’ (LAST), the experts have produced wires whose core consists of CNTs lined up in rows and protected by a plastic shell ten micrometres thick. They are just 0.3 millimetres thick and so flexible that they are suitable for use as windings for electric motors. CNTs are nanometer-sized tubes whose shells consist of carbon atoms arranged in a honeycomb pattern.

With the LAST technique, Kim and his team are solving a previously unsolved problem. Instead of connecting to form endless wires, the CNTs clump together, making them unsuitable as a replacement for copper cables. The researchers use a liquid with lyotropic properties to prevent clumping and neatly align the CNTs. At the same time, it flushes out contaminants, resulting in perfect metal-free wires that conduct electricity for electric motors.

Motor produces only 3.5 watts

If the two electric motors that power the Tesla Model S were equipped with CNT wires instead of copper wires, their weight would drop from 68 to 52.2 kilograms. In relation to the total vehicle weight, which is a good two tonnes, this is not much. However, in drones, such a weight reduction would significantly extend the operating time. The KIST motor currently has an output of 3.5 watts, which is still too weak to power most drones.