Cheaper, cleaner and with five times more energy: Researchers discover new method for building zinc-air batteries

Lithium-ion batteries could soon be replaced as the power source of choice in electronic devices as researchers have discovered how to build rechargeable zinc-air batteries.

Zinc-air batteries are batteries powered by zinc metal and oxygen from the air, which, thanks to the global abundance of zinc metal, are much cheaper to produce than lithium-ion batteries and can also theoretically store five times more energy  than that of lithium-ion batteries.

Zinc-air batteries  are also much safer and more environmentally friendly.

Featured image courtesy of the University of Sydney

However, 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.

In the journal Advanced Materials, researchers from the University of Sydney have outlined a new three-stage method to overcome this problem.

“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 the study’s lead author Professor Yuan Chen, from the University of Sydney’s Faculty of Engineering and Information Technologies.

University of Sydney researchers used a new method – creating bifunctional oxygen electrocatalysts – which allowed them to build rechargeable zinc-air batteries from scratch.

The researchers also replaced precious metal catalysts with low cost variations, which were produced through the simultaneous control of the composition, size and crystallinity of metal oxides in earth-abundant elements such as iron, cobalt and nickel.

The study’s co-author Dr Li Wei, also from the University’s Faculty of Engineering and Information Technologies, said trials of zinc-air batteries developed with the new catalysts had demonstrated excellent rechargeability – including less than a 10% battery efficacy drop over 60 discharging and charging cycles of 120 hours.

“We are solving fundamental technological challenges to realise more sustainable metal-air batteries for our society,” Chen added.

Emissions set to make extra 150 million protein deficient by 2050

Carbon dioxide emissions will result in millions of people facing the prospect of protein deficiency by 2050, according to a by Harvard T.H. Chan School of Public Health.

The study, which is published today in the journal Environmental Health Perspectives, found that the populations of 47 countries will lose over 5% of their dietary protein if projected rises in carbon dioxide emissions come to pass, as increased CO₂ reduces the nutritional value of dietary staples such as wheat and rice.

Some of the affected countries already face significant protein deficiency problems, such as countries in Sub Saharan Africa, but the projected rise is set to bring to issue to an additional 150 million people. Protein deficiency can cause, among its symptoms, muscle wasting, infections and delayed wound healing, potentially leading to a host of additional health issues.

“This study highlights the need for countries that are most at risk to actively monitor their populations’ nutritional sufficiency, and, more fundamentally, the need for countries to curb human-caused CO₂ emissions,” said Samuel Myers, senior research scientist in the Department of Environmental Health.

82% of the population gets the majority of their protein from plants, making nutritional changes as a result of increases in atmospheric CO₂ a serious concern

It was already known that a greater quantity of atmospheric CO₂ results in plants producing less protein as they grow, however this study is the first to quantify the extent.

The researchers found that under the elevated CO₂ concentrations projected to occur in the atmosphere by 2050, rice, wheat, barley and potatoes would see a drop in protein content by 7.6%, 7.8%, 14.1% and 6.4% respectively.

An additional study by Myers, which is also published today in the journal GeoHealth, found that CO₂ are also set to cause a drop in iron found in nutritional staples, increasing the chances of iron deficiency.

Add the findings of a 2015 study where Myers and colleagues found that the same elevated emissions are set to put 200 million people at risk of a zinc deficiency, and it is clear that in many parts of the world there is a serious risk to people’s health as a result of atmospheric CO₂.

New technologies such as this air scrubber by Climeworks could help reduce the rise of atmospheric CO₂, however far more needs to be done. Image courtesy of Climeworks / Julia Dunlop

The obvious solution to this is to make increased efforts to limit CO₂ emissions, however with many countries remaining sluggish in acting on climate change-related issues, it is doubtful as to whether this will be achieved.

However, it will also be important to focus dietary strategies on the affected countries, meaning primarily focusing on South Asia, Sub Saharan Africa and India, where 53 million people will be affected.

“Strategies to maintain adequate diets need to focus on the most vulnerable countries and populations, and thought must be given to reducing vulnerability to nutrient deficiencies through supporting more diverse and nutritious diets, enriching the nutritional content of staple crops, and breeding crops less sensitive to these CO₂ effects,” Myers said. “And, of course, we need to dramatically reduce global CO₂ emissions as quickly as possible.”