Affordable zinc-air cells could be the future of battery tech

Posted Aug 16, 2017 by James Walker
Researchers have developed a breakthrough method to create rechargeable zinc-air batteries. Zinc-air cells are cheap to make and could become the preferred power source for future tech. They've previously been hindered by rechargeability issues.
University of Sydney zinc-air battery
University of Sydney zinc-air battery
University of Sydney
The use of zinc-air batteries could lead to cheaper smartphones that last for longer on a charge. They're powered by oxygen from the air and a small amount of zinc, a metal that's found in abundance across the world. This leads to a production process that's far more affordable than conventional lithium-ion cells. Unfortunately, they come with one big caveat as historically they've proved difficult to recharge.
Researchers at the University of Sydney have developed a solution that could see zinc-air batteries achieve their full potential. In a press release today, the team explained that previous efforts to create rechargeable zinc-air batteries have failed due to a lack of suitable electrocatalysts. The group engineered a three-stage mechanism of avoiding this issue.
The technique involves chemically creating electrocatalysts that can reduce and generate oxygen inside the battery. This allows the battery to discharge and recharge like a regular lithium-ion cell.
The catalysts are created using metal oxides of abundant elements, such as iron, cobalt and nickel. The size, crystallinity and composition of each metal oxide has to be carefully controlled for the catalyst to function. Because the entire process relies on freely available materials, the overall cost of the batteries shouldn't be significantly impacted.
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"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 research author Professor Yuan Chen. "We are solving fundamental technological challenges to realise more sustainable metal-air batteries for our society."
The research team has observed promising results in trials of the technology. After performing 60 charging cycles of 120 hours each, a 10 percent drop in efficiency was recorded. Because zinc-air batteries can store as much as five times more energy than lithium-ion ones, the gradual efficiency decrease shouldn’t be a major issue in real-world usage.
The creation of sustainable zinc-air catalysts makes the use of the batteries as a lithium-ion replacement more feasible. Tech firms and researchers are looking to develop safer and more environmentally friendly batteries that also offer a longer runtime. Zinc-air cells now seem to be a suitable alternative to hazardous lithium-ion systems, offering a higher capacity without risking explosions or consuming precious metal resources.