Breakthrough could lead to cheaper, longer-lasting batteries

Australian and Singaporean researchers have found a solution for one of the biggest stumbling blocks preventing zinc-air batteries from overtaking conventional lithium-ion batteries as the power source of choice in electronic devices.
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A researcher holds up a rechargeable zinc-air battery. Photo: University of Sydney

Australian and Singaporean researchers have found a solution for one of the biggest stumbling blocks preventing zinc-air batteries from overtaking conventional lithium-ion batteries as the power source of choice in electronic devices.

Zinc-air batteries are batteries powered by zinc metal and oxygen from the air. Due to the global abundance of zinc metal, these batteries are much cheaper to produce than lithium-ion batteries, and they can also store more energy (theoretically five times more than that of lithium-ion batteries), are much safer, and are more environmentally friendly.

However, their widespread use has been hindered by the fact that, up until now, recharging them has proved difficult. This is due to the lack of electrocatalysts that successfully reduce and generate oxygen during the discharging and charging of a battery.

A team of chemical engineers from the University of Sydney and Nanyang Technological University have created a new three-stage method to overcome this problem.

Professor Yuan Chen, from Sydney says the new method can be used to create bifunctional oxygen electrocatalysts for building rechargeable zinc-air batteries from scratch.

“Up until now, rechargeable zinc-air batteries have been made with expensive precious metal catalysts, such as platinum and iridium oxide. In contrast, our method produces a family of new high-performance and low-cost catalysts,” he said.

These catalysts are produced through the simultaneous control of the composition, size and crystallinity of metal oxides of earth-abundant elements such as iron, cobalt and nickel. They can then be applied to build rechargeable zinc-air batteries.

The trials of zinc-air batteries developed with the new catalysts had demonstrated good rechargeability, including less than a 10 percent battery efficacy drop over 60 discharging/charging cycles of 120 hours.

“We are solving fundamental technological challenges to realise more sustainable metal-air batteries for our society,” said Chen.

[A researcher holds up a rechargeable zinc-air battery. Photo: University of Sydney]