Scientists make running a car on zero metal possible with this new research

Lightweighting is a common goal across electric vehicles, drones, and spacecraft. Lighter machines use less energy, help batteries work more efficiently, and can travel farther. It is also tied to sustainability because better overall performance can lower carbon emissions. Electric motors sit at the center of this push. Their coils make up a large share of motor weight, and most coils use copper. Copper conducts electricity well, but it brings challenges such as resource supply concerns, price swings, and added weight due to its high density.

A team led by Dr. Dae-Yoon Kim at the Korea Institute of Science and Technology (KIST) Composite Materials Research Institute has built an electric motor that uses a coil made only of carbon nanotubes (CNTs), with no metals. In tests, the team could control the motor’s revolutions per minute (RPM) in line with changes to the input voltage. That shows a motor can perform its basic job, turning electrical energy into rotational force, without using metal conductors.

CNTs are one-dimensional, tube-shaped nanomaterials with carbon atoms arranged in a hexagonal honeycomb structure. They are much lighter than common metals and are known for high electrical conductivity, strong mechanical strength, and good thermal conductivity. Even so, CNTs have faced hurdles in real-world use. A major issue is leftover catalyst metals from the manufacturing process. These metal particles stick to CNT surfaces and reduce electrical performance, which directly affects motor parts.

The KIST team developed a new CNT purification process that uses the alignment behavior of liquid crystals, a “fourth state of matter” that sits between liquid and solid. As the CNTs align, the process naturally breaks up clumps and helps remove metallic particles from the surface. The key point is that it can selectively remove impurities without damaging the CNT nanostructure. This sets it apart from many liquid- and gas-phase purification methods. The result is CNTs with much better conductivity, high enough to work in actual electric motors.

The researchers then formed coils from the purified CNTs and ran motors that showed stable RPM control with different voltages. If this approach scales, lighter coils could reduce motor weight and overall system mass. It could also ease dependence on copper and limit exposure to price and supply risks. Future work will need to compare power density, efficiency, heat handling, and cost with copper-based designs under real operating conditions.

"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."

Source: KIST | Image via Depositphotos

This article was generated with some help from AI and reviewed by an editor. Under Section 107 of the Copyright Act 1976, this material is used for the purpose of news reporting. Fair use is a use permitted by copyright statute that might otherwise be infringing.

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Posted Monday 18 August 2025 at 2:42 pm AEST (my time).

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