Lithium-ion batteries are literally everywhere nowadays. That is actually pretty unfortunate, because lithium is rare and therefore expensive. But what alternatives do we have? Zinc-air batteries are a good solution as we do have a lot of zinc. And now scientists from the University of Sydney have found a solution for one of the biggest problems preventing zinc-air from replacing conventional lithium-ion technology.
Zinc-air batteries would make energy from zinc reaction with oxygen from air – quite a simple idea, but there is one problem – they are difficult to charge. Hearing aids, some railway equipment and film cameras use zinc-air batteries, but it is difficult for them to spread to the levels of lithium-ion technology when charging is such a big issue. That is because there is not enough of electrocatalysts that are necessary to successfully reduce and generate oxygen during the discharging and charging of a battery. However, now researchers from the University of Sydney and Nanyang Technological University have developed a three-stage solution to this problem.
This new method would create bifunctional oxygen electrocatalysts for building rechargeable zinc-air batteries from scratch. Professor Yuan Chen, lead author of the study, said: “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”. Scientists achieved this new catalyst by simultaneously controlling composition, size and crystallinity of metal oxides of earth-abundant elements such as iron, cobalt and nickel. This allows building a completely different type of zinc-air battery that would be relatively easy to charge.
Initial tests showed how promising this technology really is. Over 60 discharging/charging cycles of 120 hours scientists could only observe less than a 10 % battery efficacy drop. That is excellent efficacy, but further research and experiments could improve on that greatly. In fact, zinc-air technology is better than lithium-ion batteries in pretty much all areas except charging.
First of all, zinc-air batteries are much cheaper to produce. There is so much more zinc on Earth than lithium and it is easier to extract. Furthermore, theoretically zinc-air batteries can store up to five times more energy than lithium-ion batteries, which are already praised for their capacity. Finally, zinc-air technology would be much safer and more environmentally friendly – no more exploding devices and recycling would be less of a problem. Now we have to wait until scientists will actually make a working, fully rechargeable prototype, capable of powering an everyday device.
Source: University of Sydney
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