Researchers at the University of Sydney say they have found a successful solution to one of the hurdles in the development of better zinc-air batteries.
These batteries generate electricity via the oxidation of zinc using oxygen from the air. Although some zinc-air batteries are used to power devices like hearing aids, cameras and railway signalling equipment, more widespread use has been limited by the difficulty in recharging them.
“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 lead author Professor Yuan Chen.
The team’s new method of catalytic control can be used to create bifunctional oxygen electrocatalysts, allowing new rechargeable zinc-air batteries to be built from scratch, using cheaper and more readily-available elements such as iron, cobalt and nickel.
The abstract describes a Zn–air battery produced in the lab to deliver a specific capacity of 756 mAh (representing an energy density of 904 Wh/kg) and a peak power density of 86 mW per square cm. According to co-author Dr Li Wei, these cells also showed a battery efficacy drop of under 10% over 60 discharging/charging cycles of 120 hours.
The hope is that due to the abundance of zinc, larger batteries could be made that are much cheaper to produce than comparable lithium-ion batteries, with greater energy density. Theoretically this could reach up to 1,370 Wh/kg – around five times greater than lithium-ion.