New nanomaterial invention sparks potential for phone battery recycling

Engineers at RMIT University have facilitated the potential for mobile phone battery recycling with a new rust removal invention.

Thanks to a nanomaterial innovation developed by RMIT University engineers, rather than disposing of mobile batteries after two or three years, mobile phone battery recycling could be made possible, expanding their lifetime up to three times longer than today’s technology. The team believes that we could have recyclable batteries that last up to nine years by using high-frequency sound waves to remove rust that inhibits performance.

Currently, only 10% of used handheld batteries are collected for recycling in Australia, with the remaining 90% going into landfill or being disposed of incorrectly. A major challenge to battery recycling is the high cost of recovering lithium and other metals, but the team’s innovation is set to address this barrier.

© RMIT University

The team is working with an exciting potential for lithium for batteries, a nanomaterial called MXene, which is 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,” said Leslie Yeo, Distinguished Professor of Chemical Engineering and lead senior researcher.

However, the problem with using MXene was that it rusted easily, thereby inhibiting electrical conductivity and rendering it unusable.

“To overcome this challenge, we discovered that sound waves at a certain frequency remove rust from MXene, restoring it to close to its original state,” Yeo said.

In the future, this invention could help revitalize MXene batteries every few years, extending their lifetime up to three times.

“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.

The research, titled ‘Recovery of oxidized two-dimensional MXenes through high frequency nanoscale electromechanical vibration,’ is published in Nature Communications.

How does the team’s nanomaterial innovation work?

The biggest issue with using MXene is the rust that forms on its surface in a humid environment or when suspended in aqueous solutions.

© RMIT University

“Surface oxide, which is rust, is difficult to remove especially on this material, which is much, much thinner than a human hair,” co-lead author Mr. Hossein Alijani, a PhD candidate from RMIT’s School of Engineering.

“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 oxidized 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.”

What are the potential applications of the work?

By removing rust from Mxene, the nanomaterial has the potential to be used in a wide range of applications in a variety of sectors, including energy storage, sensors, wireless transmission, and environmental remediation. The ability to restore oxidized materials to an almost pristine state is a game changer in terms of the circular economy.

“Materials used in electronics, including batteries, generally suffer deterioration after two or three years of use due to rust forming,” said Associate Professor Amgad Rezk, one of the lead senior researchers from RMIT’s School of Engineering.

“With our method, we can potentially extend the lifetime of battery components by up to three times.”

More work is required on the nanomaterial

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

They are 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.

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