Twisted carbon nanotubes show promise for more compact energy storage.

In a breakthrough that reimagines energy storage, researchers from the University of Maryland Baltimore County (UMBC) have revealed how twisting carbon tubes at the nanoscale unlocks a remarkable capacity for power, offering a safer and lighter alternative to traditional batteries with the potential to transform future technology.

For years, scientists have sought alternatives to chemical batteries that rely on complex and often hazardous materials. These conventional applications, while powering the modern world, come with limitations – safety, materials availability, and limited lifespan.

The search for safer, more sustainable energy solutions has only continued to grow as a priority, driving researchers to explore innovative methods that could expand the possibilities for energy storage and unlock new applications.

It was from this pursuit that researchers from the Center for Advanced Sensor Technology (CAST) at UMBC, in collaboration with Suwa University of Science and Shinsu University – both in Japan – uncovered an extraordinary breakthrough.

"Humans have long stored energy in mechanical coil springs to power devices such as watches and toys," said Assistant Research Scientist at CAST Sanjeev Kumar Ujjain.

The discovery takes this concept further, harnessing the mechanical properties of carbon tubes – thousands of times thinner than a human hair – where their small size and unique structure allow them to store energy far more efficiently than larger springs.

Nano-springs

In-situ micrographs observed by Preety Ahuja

Scanning electron microscope images show some carbon nanotube "ropes" subjected to different twist strains.

Achieving this advancement required a meticulous process, beginning with the selection of single-walled carbon tubes – structures made from sheets of carbon only one atom thick. These tubes, known for being lightweight, relatively easy to manufacture, and about 100 times stronger than steel, were bundled into "ropes" and subjected to a twisting process that compacted them into ultra-dense threads.

Their exceptional properties have long made them a focal point for researchers exploring futuristic technologies, like the ambitious space elevator.

After pulling and twisting the tubes into these threads, as well as coating them with different substances intended to increase the strength and flexibility of the rope, the team transformed them into a powerful and efficient mechanical energy storage system.

To evaluate the energy storage potential of their creation, the researchers conducted a series of tests on the twisted carbon ropes.

By twisting the threads to store energy and then measuring the power released as they unwound, they were able to determine the capacity of their creation, and the results were astonishing – storing 15,000 times more energy per unit mass than steel springs and three times the energy density of advanced lithium-ion batteries.

"This research shows twisted carbon nanotubes have great potential for mechanical energy storage, and we are excited to share the news with the world," said Ujjain.

With these remarkable findings in hand, the research team has been working to move their discovery from theory to practice through an immediate focus on integrating twisted carbon nanotubes into a prototype sensor that aims to showcase the material's potential in real-world applications.

By developing a proof-of-concept device, the team hopes to address challenges such as durability and scalability, which are critical for transitioning the technology from the lab to practical use.

While still in its early stages, this technology could one day address critical energy storage challenges across various fields, offering the potential for compact, reliable power in applications like medical implants and advanced sensors where size and efficiency are vital.

As the CAST team continues to refine their work, twisted carbon nanotubes represent a promising step toward reimagining how energy is stored and utilized.