Mobile Phone Batteries Prone to Rusting Recycled Using Nanoscale Electromechanical Vibrations

Engineers at RMIT University have developed a new technology that could lead to a significantly longer lifespan of mobile phone batteries. The team has found a way to use high-frequency sound waves to remove rust that hinders battery performance, which could result in recyclable batteries that last up to nine years compared to the current two or three years.

The study's analysis has been reported in the journal Nature Communications. The engineers at RMIT University are working with a material called MXene, which they believe could be an alternative to lithium for batteries. This could be a significant development as currently, only 10% of used handheld batteries, including mobile phone batteries, are recycled in Australia, which is low by international standards.

The rest either go to landfill or are disposed of incorrectly, leading to environmental damage. The high cost of recycling lithium and other materials from batteries is a major obstacle to reusing these items, but the team's innovation may help to overcome this challenge.

MXene Material

According to Leslie Yeo, distinguished professor of chemical engineering and lead senior researcher from RMIT's School of Engineering, MXene has high electrical conductivity and is similar to graphene. He stated that MXene is highly tailorable and has a wide range of potential technological applications in the future. However, one of the main challenges with using MXene is that it rusts easily, which hinders electrical conductivity and makes it unusable.

To overcome this issue, the team discovered that using sound waves of a specific frequency can remove rust from MXene, restoring it to close to its original condition. This innovation has the potential to extend the lifetime of MXene batteries up to three times by revitalizing them every few years.

Yeo also added that the ability to prolong the lifespan of MXene is crucial to making it suitable for commercial electronic parts. Hossein Alijani, a Ph.D. candidate from RMIT's School of Engineering and co-lead author of the research, said that the biggest challenge with using MXene was the rust that forms on its surface when exposed to humidity or watery solutions. Alijani explained that it is difficult to remove the rust, especially on MXene, which is much thinner than a human hair. Currently, methods to reduce oxidation involve chemically coating the material, which limits the use of MXene in its natural form.

Experimental setup and materials characterization. A, C Top, and, (B, D) side view schematics of the experimental setup in which a 5 µm thick oxidized Ti3C2Tz MXene film (a scanning electron microscopy (SEM) image of which is shown in (E)) is placed atop the surface reflected bulk wave (SRBW) resonator, which comprises a chipscale single-crystal LiNBO3 piezoelectric substrate, shown in (F). In (C, D), the SRBW—generated by applying a sinusoidal electrical signal from a radio frequency (RF) source to interdigital transducer (IDT) electrodes photolithographically patterned onto the LiNbO3 substrate—propagates along and through the substrate and is transmitted into the Ti3C2Tz MXene film through a thin water coupling layer. In the control experiment (A, B), the SRBW is not excited. G Powder x-ray diffraction (XRD), and, (H) Raman spectra of the pristine, control (oxidized) and SRBW-irradiated films MXenes at different powers. Nature Communications (2023). DOI: 10.1038/s41467-022-34699-3

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Recycling Phone Batteries

However, the team's research shows that exposing an oxidized MXene film to high-frequency vibrations for just one minute can remove the rust and restore the material's electrical and electrochemical performance. The team claims that their work to remove rust from Mxene makes it possible to use the nanomaterial in energy storage, sensors, wireless transmission, and environmental cleanup.

One of the principal senior researchers, Associate Professor Amgad Rezk from RMIT's School of Engineering, stated that the capability to restore oxidized materials to an almost pristine state rapidly was a game changer in terms of the circular economy, as reported by Phys. Rezk mentioned that the materials utilized in electronics, including batteries, typically suffer deterioration due to the formation of rust after two or three years of use. He added that they might be able to triple the life expectancy of battery components using our approach.

The team must collaborate with the industry to incorporate its acoustics device into existing manufacturing processes and systems, despite the innovation's promising potential. In addition, the team is looking into how their invention could be used to remove oxide layers from other materials for use in sensing and renewable energy. Yeo emphasized that they are eager to collaborate with special partners in the industry so that their method of rust removal can be scaled up.