Revolutionary Motor Runs Without Metal Coils

Researchers at the Korea Institute of Science and Technology (KIST) have created a new type of lightweight, highly conductive carbon nanotube (CNT) wiring that completely eliminates the need for copper or aluminum. Using a technique called Lyotropic Liquid Crystal-Assisted Surface Texturing (LAST), they developed core-sheath composite electric cables (CSCEC) that are not only efficient conductors but also flexible and extremely lightweight.

Each CSCEC wire measures just 0.3 mm thick, including insulation—featuring a ~256-μm conductive core and a 10-μm sheath—roughly the thickness of a business card, yet still capable of powering a rotating motor.

So far, these CSCECs have successfully replaced all the copper wiring in a compact CNT-based electric motor used to power a model car.

“We developed a novel, high-performance CNT technology unlike anything before, allowing us to optimize the electrical capabilities of CNT coils and drive electric motors entirely without metal,” said Dr. Dae-Yoon Kim of KIST.

Revolutionizing CNT Performance with the LAST Process

The key breakthrough was the LAST process. By using lyotropic liquid crystals—a unique state of matter that flows like a liquid while retaining some crystalline structure—it aligns and separates carbon nanotubes that would otherwise cluster together. When paired with a chemical rinse, this method also eliminates metal catalyst residues left from manufacturing, all while preserving the crucial one-dimensional nanostructure that gives CNTs their remarkable properties.

This approach enhances conductivity by more than 130%, significantly reduces weight, and ensures long-term stability in the performance of the CSCECs.

When it comes to maximizing efficiency, battery life, range, and overall performance, reducing weight is crucial.

While electric motors are already lighter than internal combustion engines, they still carry substantial weight—largely due to the copper windings in their stators and the extensive copper wiring throughout the vehicle.

KIST’s recent advancements are focused on electric motors, but there’s hope this technology could extend to broader electrical applications.

How CSCEC Wiring Transforms BEV Efficiency and Dynamics

Consider battery electric vehicles (BEVs) like the dual-motor Tesla Model S. Its front motor weighs around 70 lb (31.8 kg) and the rear about 80 lb (36.3 kg), with copper windings accounting for roughly 25% of that total. Replacing them with CSCEC wiring could potentially reduce combined motor weight from 150 lb (68 kg) to about 115 lb (52.2 kg).

Though a 35 lb (15.8 kg) reduction might seem minor in a 4,561 lb (2,069 kg) car, the benefits extend beyond just weight savings. Less rotating mass leads to quicker acceleration, improved throttle response, more efficient torque delivery, and reduced mechanical losses. Additionally, with less heat generated, cooling systems can be smaller and lighter—triggering a chain reaction of improvements that contribute to better battery efficiency and extended range.

Of course, that scenario is purely theoretical, based on actual Tesla data. In reality, KIST’s motor was tested at just 2 to 3 volts and 3.5 watts—far below the power levels required for any full-sized electric vehicle, and more comparable to what’s used in toy-grade applications.

Since we’re already venturing into hypotheticals, let’s push it a bit further: While there’s no official data on the exact amount of copper used in Joby’s aircraft, a reasonable estimate might put the wiring harness alone at around 200–300 lb (91–136 kg), given the need for redundant systems. Add to that six motors, each potentially containing 30–40 lb (13.6–18.1 kg) of copper windings, and you’re looking at a total copper load of roughly 180–240 lb (81.6–108.9 kg).

High Stakes in High Voltage

Now, KIST’s research so far has focused solely on low-voltage motor windings. But if they eventually manage to scale CSCEC technology to handle high-voltage applications and general wiring, it could potentially cut 300–500 lb (136–227 kg) from a leading eVTOL like Joby’s. Ask any Joby engineer if they’d want to remove a quarter ton from their aircraft, and they’d likely be stunned—then quickly say yes.

That said, back in the real world, there are still important limitations to consider.

Even after applying the LAST process, CNT wiring doesn’t yet rival copper in raw electrical conductivity (~7.7 megasiemens per meter vs. copper’s 59 MS/m). With identical size and voltage, CNT wiring carries less current, resulting in lower power output. For example, in KIST’s study, the CNT motor maxed out at 3,420 RPM, while the copper-based version reached 18,120 RPM.

However, the CNT motor’s conductor core weighed only one-fifth as much as its copper counterpart. That gives it a specific rotational velocity—a key metric in aerospace where weight matters more than raw force—only about 6% lower than copper’s. In terms of performance per unit weight, CNT isn’t too far behind.

Cost is another major factor. Producing specialized carbon nanotube core-sheath composite electric cables can run anywhere from US$375 to $500 per kilogram, compared to just $10–11 per kilogram for copper.

And this isn’t a simple plug-and-play substitution. Replacing copper with CNT technology would require engineers to completely redesign components—everything from insulation materials to winding configurations would need to be rethought.

Closing the Gap

Researchers believe further refinements, such as improving polymer sheaths or achieving better CNT alignment, could enhance conductivity and narrow the performance gap with copper.

While CNTs offer significant weight savings, their production still comes with notable environmental downsides. Most are manufactured using fossil fuel-based processes that are energy-intensive and produce harmful byproducts. For instance, the LAST method involves chlorosulfonic acid and generates hydrochloric acid during the rinsing stage, raising sustainability concerns.

Read the original article on: New Atlas

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