Zinc-air batteries are batteries powered by zinc metal and oxygen from the air. Due to the global abundance of zinc metal, the researchers claim these batteries are much cheaper to produce than lithium-ion batteries, but that they can also store more energy, are much safer and are more environmentally friendly.
While zinc-air batteries are currently used as an energy source in hearing aids and some film cameras and railway signal devices, 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.
To overcome this problem, the researchers have outlined a three-stage method to create bifunctional oxygen electrocatalysts for building rechargeable zinc-air batteries.
"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," said Sydney Professor Yuan Chen.
The catalysts are said to be produced through the simultaneous control of the composition, size and crystallinity of metal oxides of earth-abundant elements such as iron, cobalt and nickel.
According to the team, trials of zinc-air batteries developed with the new catalysts have demonstrated excellent rechargeability – including less than a 10% battery efficacy drop over 60 discharging/charging cycles of 120 hours.
