Diamond nanothreads could be used to store energy

Researchers at Queensland University of Technology (QUT) have proposed the design of a new carbon nanostructure made from diamond nanothreads that could one day be used for mechanical energy storage, wearable technologies and biomedical applications.

Dr Haifei Zhan, from the QUT Centre for Materials Science, and his colleagues successfully modelled the mechanical energy storage and release capabilities of a diamond nanothread (DNT) bundle — a collection of ultrathin one-dimensional carbon threads that store energy when twisted or stretched. Their work was published in the journal Nature Communications.

“Similar to a compressed coil or children’s wind-up toy, energy can be released as the twisted bundle unravels,” Dr Zhan said.

“If you can make a system to control the power supplied by the nanothread bundle, it would be a safer and more stable energy storage solution for many applications.”

The new carbon structure could be a potential microscale power supply for anything from implanted biomedical sensing systems monitoring heart and brain functions to small robotics and electronics.

“Unlike chemical storage such as lithium-ion batteries, which use electrochemical reactions to store and release energy, a mechanical energy system itself would carry much lower risk by comparison,” Dr Zhan said.

“At high temperatures chemical storage systems can explode or can become non-responsive at low temperatures. These can also leak upon failure, causing chemical pollution.

“Mechanical energy storage systems don’t have these risks, [making] them more suited to potential applications within the human body.

“Carbon nanothread bundles could be made into twist-spun yarn-based artificial muscles that respond to electrical, chemical or photonic excitations.

“Previous research has shown such a structure made with carbon nanotubes could lift 50,000 times its own weight.”

Dr Zhan’s team found the nanothread bundle’s energy density — how much energy it could store for its mass — was 1.76 MJ/kg, which is 4–5 orders higher than a conventional steel spring and up to three times higher compared to Li-ion batteries.

“Energy-dense materials are very important to many applications, which is why we are always looking for lightweight materials that still perform well,” Dr Zhan said.

“The benefits for aerospace applications are obvious. If we can reduce the weight of a system, we can significantly reduce its fuel requirements and costs.”

The application of carbon nanothread bundles as an energy source could be endless, with Dr Zhan saying they could be used “in next-generation power transmission lines, aerospace electronics, and field emission, batteries, intelligent textiles and structural composites such as building materials”.

Dr Zhan and his team are now planning production of an experimental nanoscale mechanical energy system as proof of concept. The team will spend the next two to three years building the control mechanism for the system to store energy — the system which controls twisting and stretching of the nanothread bundle.