An international team of scientists from the Center for Advanced Sensor Technology demonstrated the ability of twisted carbon nanotubes to store three times more energy per unit mass than sophisticated lithium-ion batteries. The discovery could make carbon nanotubes a more viable option for energy storage in small, light, and secure devices like medical implants and sensors. The study was published in the journal Nature Nanotechnology.
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Sanjeev Kumar Ujjain from CAST was the lead researcher on the project. He began the project while attending Shinshu University in Nagano, Japan, and continued it when he moved to UMBC in 2022. Preety Ahuja from CAST also contributed to the research's material characterization sections.
The researchers studied single-walled carbon nanotubes, which resemble straws formed of pure carbon sheets that are only one atom thick. About 100 times stronger than steel, carbon nanotubes are lightweight and relatively simple to make. Scientists are investigating the possibility of using these remarkable qualities in various futuristic-sounding technologies, such as space elevators.
The UMBC researchers and their colleagues created carbon nanotube “ropes” using bundles of commercially available nanotubes to examine the potential of carbon nanotubes for energy storage. The tubes were pulled and twisted into a single thread by the researchers, who then coated them with various materials to improve the strength and flexibility of the ropes.
By twisting the ropes and measuring the energy released as they unraveled, the team determined how much energy they could hold. They discovered that the most efficient ropes could store almost three times as much energy as lithium-ion batteries and 15,000 times more energy per unit mass than steel springs.
At temperatures between -76 and +212 °F (-60 and +100 °C), the stored energy is stable and accessible. The carbon nanotube ropes' constituent elements are also less harmful to human health than those found in batteries.
Humans have long stored energy in mechanical coil springs to power devices such as watches and toys. This research shows twisted carbon nanotubes have great potential for mechanical energy storage, and we are excited to share the news with the world.
Sanjeev Kumar Ujjain, Lead Researcher, Center for Advanced Sensor Technology, University of Maryland
He notes that the CAST team is currently exploring using twisted carbon nanotubes as an energy source for a prototype sensor they are designing.
Journal Reference:
Utsumi, S., et al. (2024) Giant nanomechanical energy storage capacity in twisted single-walled carbon nanotube ropes. Nature Nanotechnology. doi.org/10.1038/s41565-024-01645-x.