Electric motor with carbon nanotubes

 Carbon Nanotube Revolution : Electric motor with carbon nanotubes by Korean scientists

Scientists in South Korea have built the world’s first functional electric motor without any metal components, replacing traditional copper coils with ultra-lightweight carbon nanotubes (CNTs). The breakthrough, led by the Korea Institute of Science and Technology (KIST), boosts electrical conductivity by 133% while cutting motor weight by more than 80%. Researchers built a small electric motor which uses cables made entirely of carbon nanotubes, rolled graphene cylinders a few nanometers wide. The motor runs without copper wire, trimming weight while keeping useful speed at low voltage. The team’s result points toward lighter wiring for cars and planes. It also suggests a path to cut manufacturing emissions by replacing heavy metals with precise carbon structures. This could mark a new chapter in lightweight engineering, from electric vehicles to spacecraft and beyond. “By developing a new concept of CNT high-quality technology which 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, lead researcher at KIST.

Each cable has a core-sheath composite, a conductive core with an insulating wrap. The core is a bundle of continuous nanotube wires about 11.8 inches long in the prototype. A surface-cleaning step improves the wire. The team uses chlorosulfonic acid, a powerful acid which dissolves nanotube bundles, then removes residual metals that can block electrons. The texturing step is called LAST, a controlled surface process which boosts order. Cleaner surfaces and better alignment reduce the points where electrons scatter. Those changes raise the effective electrical conductivity. The cable’s conductivity reached 7.7 million siemens per meter in testing. CNTs are hexagonal honeycomb-structured nanomaterials with outstanding electrical, mechanical, and thermal properties. But for decades, metal catalyst impurities from their production process prevented CNTs from replacing copper in serious hardware. Lead researcher Ki-Hyun Ryu of the Korea Institute of Science and Technology (KIST) led the project. The group describes cables that combine aligned nanotube wires with a thin insulating jacket. The researchers used a process called lyotropic liquid crystal, a fluid phase where rodlike molecules align, to organize the nanotubes. This alignment lets many tiny conductors act more like one continuous wire. “We successfully powered a scale model car using a metal-free motor made from high-performance CSCECs,” stated Ryu. The demonstration motor operated on 3 volts and maintained steady rotation. It pushed a toy car along a short track, showing that the concept works outside the lab.

KIST’s breakthrough came with a new purification technique called the LAST (Lyotropic Liquid Crystal-Assisted Surface Texturing) process. Inspired by LCD technology, this method:-

Removes metal contamination with hydrochloric acid

Aligns CNTs in a liquid crystal state

Preserves the tubes’ electrical structure

The step from ideal nanotubes to bulk fibres brings junction resistance, extra resistance where filaments touch. Those junctions lower macroscopic conductivity compared with single tubes. Individual nanotubes can tolerate enormous current density, electric current per unit area, up to about 10^9 amperes per square cm in experiments.  Bundling thousands together without losing the strength remains a key challenge. Cost and scale also matter. Spinning long, uniform fibres with low impurities is difficult, and processing routes can be energy intensive. Even with those hurdles, steady gains in alignment and purity are lifting performance. The latest results show a clean route to improve output without adding metal.

The metal impurities dropped from 12.7% to less than 0.8%, and conductivity shot up to 7.7 megasiemens / meter, a record for CNT wires. At 3 volts, the carbon motor reached 3,420 revolutions / minute. A similar copper coil reached 18,120 revolutions per minute at the same voltage, but it weighed much more. Copper’s typical conductivity is about 5.9×10^7 siemens / meter. That helps explain copper’s higher speed today. Weight tells another story. Nanotube wire is roughly one fifth as dense as copper, which means big mass savings in coils and harnesses. Specific performance, speed per unit mass, narrows the gap. The prototype’s cables stayed stable for at least one hour at power levels up to 3.5 watts.  The researchers demonstrated their motor by powering a toy car that reached a speed of 0.52 meters per second, not lightning fast, but impressive given the ultra-lightweight motor. The CNT coils weighed just 78.75 mg, compared to 379.08 mg for copper. Even though copper motors still delivered higher top speeds, the weight-adjusted performance (specific rotational velocity) of CNT motors was nearly equivalent, just 1.06x lower. The endurance matters for moving from table top tests to real devices.

Wiring is a quiet energy drain in modern cars, especially battery models which carry heavy harnesses, bundled cable sets that link major systems. Replacing metal with lighter conductors can extend range and free space. Using recycled metals already cuts manufacturing emissions significantly. One industry report found that replacing virgin copper with regenerated material in wiring harnesses can reduce CO2 output by up to 72 % without sacrificing performance. Nanotube cables could push that further by reducing weight at the source. Less mass means less energy to move the vehicle, especially in stop and go traffic. Safety rules and connector standards will need updates if new conductors enter production. The geometry and thermal behaviour of coils may change as metals give way to carbon structures. Even more impressively, the CNT motor operated continuously for 60 minutes under various power loads, showing early signs of real-world reliability. The motor’s heart is the orderly flow of electrons through a network. Better order reduces scattering, random deflections and waste electrical energy. Alignment lets more of the current travel straight along the wire axis. This lowers voltage drop and heat for the same power. The work also shows the value of careful surface control. Removing catalyst particles reduces defect sites which can trap charge or start failures.

The improvements add up to a cable which punches above its raw conductivity number. The cable’s low density makes every watt go further per unit weight. A fair question is what happens at the end of life. Recent work shows that nanotube sheets can be recycled and re-spunned with little loss of properties. That approach preserves alignment and conductivity after recovery. It points to a circular pathway for high performance carbon conductors. Processing chemistry also deserves care. The same solvents which unlock dispersion must be recovered and neutralized responsibly. Clear rules and closed loop systems will be needed if production scales up. The materials community is already testing those controls. The CNT-based motor is more than a curiosity, it’s a harbinger of radical change for industries which count every gram and watt. Following are the some of the important details:-

Spacecraft & Aerospace

Improve manoeuvrability in low-gravity environments

Slash launch costs by reducing payload mass

Potential radiation resistance

Marine & Subsea Systems

Corrosion-proof design for oceanic drones

Enhanced buoyancy and lifespan in deep-sea conditions

Electric Vehicles

Increase efficiency without sacrificing torque

Extend range through weight reduction

Enable smaller, more flexible vehicle designs

Robotics & Automation

Lighter robotic arms with high torque output

Replace bulky copper coils in precision robotics

Drones & Urban Air Mobility

Boost flight time by reducing power draw

Lighten motors for more agile designs

Medical Devices

Enable MRI-safe, non-metallic motors for implants and tools

Lower weight improves patient mobility and device endurance

Energy Storage & Batteries

Thermal-conductive CNTs assist in heat management

Replace traditional conductive wires with lighter builds

Semiconductor Manufacturing

Carbon-based pellicles and cables reduce contamination

Improve cable durability in cleanroom environments

Beyond motors, nanotube conductors already help batteries. They act as conductive additives, tiny agents which connect active particles, improving charge flow in electrodes. Future steps include thicker coils, better heat paths and optimized insulating jackets. Each helps translate lab gains into durable parts. Automakers will ask about crash safety, repair and diagnostics. Those questions are solvable with smart design and testing. If engineers can keep raising conductivity while holding down cost, copper free coils could find their niche. The first working motor is a practical signpost. KIST plans to:-

Improve insulation for thermal management

Explore untested CNT variants

Light, efficient and metal-free systems

Refine full motor architectures optimized for CNTs

Entire electric drive systems made of carbon, from wiring to coils to interconnects

This isn’t just about ditching copper, it’s about redefining what’s possible in electric engineering. If silicon was the key to digital logic, carbon nanotubes may be the key to next-generation electro-mechanics.