Moving a step closer to recyclable phone batteries

Engineers at RMIT University have developed an innovation that could see mobile phone batteries with a lifetime up to three times longer than today’s technology.

By using high-frequency sound waves to remove rust that inhibits battery performance, batteries could be recyclable and last up to nine years instead of the typical two or three years.

In Australia, only 10% of used handheld batteries, including for mobile phones, are collected for recycling. The remaining 90% of batteries go to landfill or are disposed of incorrectly, which can cause damage to the environment.

A major barrier to these items being reused is the high cost of recycling lithium, but that challenge could be addressed by the team’s research. They are working with a nanomaterial called MXene, a class of materials that may be used as an alternative to lithium for batteries in the future.

Leslie Yeo, Professor of Chemical Engineering and lead senior researcher, said MXene was similar to graphene with high electrical conductivity.

“Unlike graphene, MXenes are highly tailorable and open up a whole range of possible technological applications in the future,” Yeo said.

A challenge with using MXene was that it rusted easily, inhibiting electrical conductivity and rendering it unusable. The researchers overcame this by using sound waves at a certain frequency to remove rust and restore it to close to its original state.

“The ability to prolong the shelf life of MXene is critical to ensuring its potential to be used for commercially viable electronic parts,” Yeo said.

How the innovation works

Co-lead author Hossein Alijani, a PhD candidate, said the rust that forms on the surface on MXene in a humid environment or when suspended in watery solutions was its greatest challenge.

“Surface oxide, which is rust, is difficult to remove especially on this material, which is much, much thinner than a human hair,” Alijani said.

He said current methods used to reduce oxidisation rely on chemical coating of the material, which limits its use.

“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,” he said.

Potential applications

The team’s method of removing rust from MXene opens the door for the nanomaterial to be used in applications in energy storage, sensors, wireless transmission and environmental remediation.

Associate Professor Amgad Rezk, one of the lead senior researchers, said, “Materials used in electronics, including batteries, generally suffer deterioration after two or three years of use due to rust forming. With our method, we can potentially extend the lifetime of battery components by up to three times.”

Next steps

While the innovation is promising, the team needs to work with industry to integrate its acoustics device into existing manufacturing systems and processes.

The team is also exploring the use of their invention to remove oxide layers from other materials for applications in sensing and renewable energy.

“We are keen to collaborate with industry partners so that our method of rust removal can be scaled up,” Yeo said.

The research paper ‘Recovery of Oxidized Two-Dimensional Titanium Carbide Ti3C2Tz MXene Films Through High Frequency Nanoscale Electromechanical Vibration’ was published in Nature Communications.

Image caption: Hossein Alijani and Dr Amgad Rezk with the new rust-busting device. Image credit: RMIT University