RMIT’s Hossein Alijani with the new rust-busting device. Photo: RMIT University.
RMIT’s Hossein Alijani with the new rust-busting device. Photo: RMIT University.

Mobile phone batteries with a lifetime up to three times longer than today’s technology could soon be a reality thanks to an innovation led by engineers at RMIT University in Australia. Rather than disposing of batteries after two or three years, recyclable batteries could last for up to nine years, by using high-frequency sound waves to remove the rust that can inhibit the performance of a novel battery technology.

Only 10% of used handheld batteries, including those in mobile phones, are collected for recycling in Australia, which is low by international standards. The remaining 90% of batteries go to landfill or are disposed of incorrectly, causing considerable damage to the environment. The high cost of recycling lithium and other materials from batteries is a major barrier to these items being reused, but the team’s innovation could help to address this challenge.

The engineers are working with a nanomaterial called MXene, a class of materials that they say promises to be an exciting alternative to lithium for batteries in the future.

According to Leslie Yeo, professor of chemical engineering and lead senior researcher, MXene 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,” he said.

The big challenge 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.”

The team’s innovation could one day help to revitalise 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,” said Yeo. He and his colleagues report their findings in a paper in Nature Communications.

Rust can form on the surface of MXene in a humid environment or when it is suspended in watery solutions. “Surface oxide, which is rust, is difficult to remove especially on this material, which is much, much thinner than a human hair,” said Hossein Alijani, a PhD candidate in RMIT’s School of Engineering and co-lead author of the paper. “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 engineers say that their work to remove rust from MXene opens the door for the nanomaterial to be used in a wide range of applications in energy storage, sensors, wireless transmission and environmental remediation.

According to Amgad Rezk, an associate professor in RMIT’s School of Engineering, the ability to quickly restore oxidised materials to an almost pristine state represents a gamechanger 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,” he said. “With our method, we can potentially extend the lifetime of battery components by up to three times.”

While the innovation is promising, the engineers need to work with industry to integrate their acoustics device into existing manufacturing systems and processes. They are also exploring the potential of using 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.

This story is adapted from material from RMIT University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.