University of Sydney 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).
They 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.
A paper authored by chemical engineering researchers
from the University of Sydney and Nanyang
Technological University outlines a new three-stage
method to overcome this problem.
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, the new method produces a family
of new high-performance and low-cost catalysts
These new catalysts are produced through the
simultaneous control of the: 1) composition,
2) size and 3) 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.
Trials of zinc-air batteries developed with
the new catalysts had demonstrated excellent
rechargeability – including less than a
10 percent battery efficacy drop over 60 discharging/charging
cycles of 120 hours.
