Diamonds may shine in energy storage

Australian researchers have proposed the design of a new carbon nanostructure made from bundles of diamond nanothreads.

Haifei Zhan and colleagues from QUT describe their approach – based around ultrathin one-dimensional carbon threads that store energy when twisted or stretched – in a paper 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,” says Zhan. 

It’s early days, but the researchers say the new structure has the potential to provide micro-scale power supply for applications across sensing, robotics and electronics.

And a mechanical system is lower risk than options such as lithium ion (Li-ion) batteries, which use electro-chemical reactions to store and release energy.

They found that the energy density of a nanothread bundle – how much energy it could store for its mass – was 1.76 MJ per kilogram, which was four to five orders higher than a conventional steel spring, and up to three times more than 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,” says Khan.

“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.”

Zhan and his team are now planning production of an experimental nanoscale mechanical energy system as proof of concept.

They will spend the next two to three years building the mechanism for the system that controls twisting and stretching of the nanothread bundle.