University of Sydney develops rechargeable zinc-air battery solution

The university's zinc-air batteries have high energy densities and are more environmentally friendly, meaning they could be applied to electronic devices in place of lithium-ion batteries.
Written by Jonathan Chadwick, Contributor

A rechargeable zinc-air battery.

The University of Sydney

Chemical engineering researchers at the University of Sydney (USyd) and Nanyang Technological University in Singapore have developed a solution for recharging zinc-air batteries that could see them applied to electronic devices in place of lithium ion batteries.

According to professor Yuan Chen, lead author of the solution, published in Advanced Materials, zinc-air batteries were previously used with expensive metal catalysts such as platinum and iridium oxide, which has limited their application to a small proportion of electronic devices, such as hearing aids and railway signals.

The newly-developed method instead uses high-performance, low-cost catalysts, produced through the control of the composition, size, and crystallinity of metal oxides of elements such as iron, cobalt, and nickel.

These can "overcome the sluggish oxygen evolution and oxygen reduction reaction (OER/ORR) in many electrochemical energy-conversion devices," the paper reads.

Trials of the new zinc-air batteries developed with the new catalysts had a 10 percent battery efficacy drop over 60 discharging/charging cycles of 120 hours, which could lead to their application in electronic devices, said USyd's Dr Li Wei who co-authored the paper.

"Our method produces a family of new high-performance and low-cost catalysts," said professor Yuan Chen from USyd's Faculty of Engineering Technologies. "We are solving fundamental technological challenges to realise more sustainable metal-air batteries for our society."

Zinc-air batteries are a type of metal-air battery powered by the oxidization of zinc by the air. Due to a global abundance, they are cheaper to produce than lithium-ion batteries -- one of the most popular types of rechargeable batteries for electronics.

Zinc-air batteries can also store five times more energy than lithium ion, are safer, and are more environmentally friendly, the university said.

Lithium-ion batteries are light and effective at delivering power quickly, making them the default technology for smartphones and electric cars such as those made by Tesla. They also contain pressurised, combustible materials, which can have severe effects after internal short circuiting.

Lithium-ion batteries proved to be the culprit for Samsung's faulty Galaxy Note 7 smartphone, which was discontinued last year due to explosions.

Batteries from both of Samsung's suppliers for the phone, Samsung SDI and ATL, were faulty, leading to internal short-circuiting that caused explosions, Samsung later found.

Other battery alternatives include magnesium, which doesn't degrade as much as lithium during the charge-discharge cycle, and graphene, also used to enhance electrode structures.

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