What You Should Know About Zinc-Air Batteries

Zinc-air batteries and fuel cells are traditionally long-lasting, low output devices. A new innovation may improve their output and make them a good choice for cheap, environmentally friendly energy storage.

Imagine a battery that derives its power from the oxygen in the air. Now imagine that such a device has been in use since the early 19th Century.

Zinc-air batteries and fuel cells have proven useful in multiple fields for being long-duration, low-output power sources, but industry 4.0 may change that. A new catalyst has been developed by researchers in Singapore that can boost its output, making it a possible candidate for powering electric vehicles.

More About the Battery

Zinc-air batteries get their power by oxidizing zinc from oxygen in the air.

They come with high energy densities, making them long-lasting. Plus, they are cheap to make in sizes ranging from the button cells in hearing aids to railway navigation aids.

The negative electrode in the battery has zinc metal in it. That zinc is bathed in hydroxide ions that react with the zinc, therefore discharging electrons. Those electrons flow to a positive electrode, generating a current as they go, and that’s where oxygen comes into the picture and creates a reaction that produces more hydroxide ions. Those extra ions are where the power in the battery comes from.

The environmental friendliness is an improvement over previous technologies, but it isn’t perfect.

On the one hand, zinc-air batteries allow producers to replace older mercury-based models.

On the other, zinc corrosion can produce explosive hydrogen, so poor design or construction could be a serious issue in making more powerful zinc-air batteries.

The trick with zinc-air power sources is increasing the speed of the reaction between the zinc and oxygen, and Yun Zong and Zhaolin Liu of the A*STAR Institute of Materials Research have developed a catalyst that may be the key to making batteries powerful and stable enough to be used in vehicles.

Working With a new Catalyst

The pair of researchers developed a nanoparticle catalyst made of a cobalt core encased by an inner shell of cobalt oxide and an outer shell of pyrolyzed polydopamine (PPD), which is a form of carbon that is ‘dotted’ with nitrogen atoms.

The nanoparticles act as an electrode, and their structure aids in preventing them from leaching cobalt or clumping together while also making the outer shell more durable.

Oxygen was transformed to hydroxide in a single step when using the nanoparticle catalyst.

According to the team, the catalyst helps the electrons flow more efficiently into the oxygen atoms.

The nitrogen in the PPD help make the oxygen more reactive as well, so with that and the improved flow of electrons, the researchers were able to test their battery at 1.36 volts over five days- a number that outperforms an electrode that relied on a conventional platinum catalyst in testing.

This is arguably just one step in making a better battery, but it is a promising step. According to Zong, “The next stage of this research includes the simplification of the synthetic route to facilitate large scale synthesis of the nanoparticles, and exploitation of other catalytic systems following the similar strategy.”

Understanding Possible Applications

With larger zinc-air fuel cells, we would have access to a long-lasting battery that is safe, has comparatively little environmental impact, and uses a rechargeable fuel source.

That kind of technology is the perfect power source for electric vehicles and improving power grid storage, all at a far lower cost than current battery technologies.

Zinc-air fuel cells have an advantage over lithium batteries that make them suitable for vehicles, specifically that the Earth’s supply of zinc is 100 times greater than that of lithium.

Producing an electric engine isn’t so expensive when the materials for it aren’t rare. Such engines have been put into use in buses Singapore already, and they have the potential to be produced for the whole world without going through a shortage of rare materials.

Grid storage would also benefit from zinc-air batteries. Energy providers such as Con Edison in New York are testing a zinc-air battery made by Urban Electric Power.

We may be a step or so away from implementing this kind of technology, but the outlook is good for the future of zinc-air batteries.