A High-Frequency Blast of Sound Could Push Future Batteries to a Nine-Year Lifespan, Ease Recycling

A team of researchers from Australia's RMIT University and Sweden's Linköping University claim to have come a step closer to being able to economically recycle mobile phone and other currently-lithium-based batteries — while also extending their usable lifespans up to nine years.

"Materials used in electronics, including batteries, generally suffer deterioration after two or three years of use due to rust forming," explains Amgad Rezk, RMIT School of Engineering associate professor, of the potential impact of the team's work. "With our method, we can potentially extend the lifetime of battery components by up to three times."

Lithium-based batteries are highly prized for their impressive energy capacity, providing a means to power even high-drain devices like modern smartphones from a compact footprint. Their lifespans, however, are limited, and recycling them once they have expired is difficult and expensive — to the point where estimates suggest just 10 per cent of handheld-device batteries are actually recycled in Australia, with the remainder being dumped in landfill.

To solve the problem, the engineers turned to MXene nanomaterials, which could be used to create lithium-equivalent batteries that are more easily recycled. MXenes, however, rust easily — making them too short-lived. The fix: blasting them with sound waves when the performance begins to drop. "We discovered that sound waves at a certain frequency remove rust from MXene," explains lead senior researcher and professor Leslie Yeo of the work, "restoring it to close to its original state."

"Surface oxide, which is rust, is difficult to remove especially on this material, which is much, much thinner than a human hair," explains co-lead author Hossein Alijani. "“Current methods used to reduce oxidation rely on the chemical coating of the material, which limits the use of the MXene in its native form. In this work, we show that exposing an oxidised MXene film to high-frequency vibrations for just a minute removes the rust on the film. This simple procedure allows its electrical and electrochemical performance to be recovered."

The team believes that an MXene-based battery could be easily treated in a way that extends their usable lifespan beyond today's lithium batteries — up to nine years per cell, Rezk suggests. The engineers are also investigating the sound-based rust-removal approach for the integration of nanomaterials into other devices, including sensors and renewable energy systems — but while industry partners are being sought, there is no commercialization deal yet on the table.

The team's work has been published in the journal Nature Communications under open-access terms.