The stakes are rising with each passing day for energy storage. The world needs it, and it needs it cheaply and urgently, given all the plans in Europe, Asia, and the United States to considerably boost the amount of renewable energy in the power generation mix. As a result, breakthroughs in energy storage tech have become more or less a regular occurrence. The latest of these breakthroughs promises to solve the two challenges of energy storage: price and capacity.
It does that by using seawater for a battery's electrolytes instead of solvents, which are much more expensive but also less safe than water.
"The world's energy needs are increasing, but the development of next-generation electrochemical energy storage systems with high energy density and long cycling life remains technically challenging," says Xhenxing Feng, a chemical engineer from Oregon State University, which published the research, as quoted by Science Daily.
"Aqueous batteries, which use water-based conducting solutions as the electrolytes, are an emerging and much safer alternative to lithium-ion batteries. But the energy density of aqueous systems has been comparatively low, and also the water will react with the lithium, which has further hindered aqueous batteries' widespread use."
To solve the energy density challenge, the researchers made a whole new nanostructured alloy for the anode of their aqueous battery. The anode combines manganese, zinc, and other metals. The zinc boosted the battery's energy density because it could transfer twice as many charges as lithium, according to Feng. The other elements of the anode increased the battery's safety by preventing the formation of dendrites that tend to form in overcharged lithium-ion batteries, sometimes resulting in spontaneous combustion.
Scientists in Germany are also working on aqueous batteries, as labs around the world push the boundary beyond lithium ions. This team, however, focused on zinc-air batteries, which have a lot of advantages such as energy density and stability but are, unfortunately, non-rechargeable.
Or at least they weren't rechargeable until now.
Working with scientists from China and the United States, the researchers from the Westphalian Wilhelms University in Münster developed a new electrolyte for a zinc-air battery that is based on seawater, replacing the alkaline solutions that are typically used. They also introduced an anode based on a zinc salt that made the battery not just rechargeable, but quite durable, too, potentially able to compete with lithium-ion battery chemistry.
Both batteries would need a lot more work before they get out of the lab and reach the market. So at least for now, lithium-ion technology's dominance is ensured. But it may not be ensured for long if efforts persist in finding safer and, perhaps more importantly, cheaper alternatives.
The United States alone plans to boost its energy storage capacity by as much as 525 percent by 2025. Storage is already being added at a fast rate: the amount set up in the third quarter of 2020 was 240 percent higher than the amount set up in the second quarter, all despite the raging pandemic.
At the same time, current storage capacity is very far from sufficient to power the grid for more than an hour or two, which makes it fit for a replacement of peaker plants but not much else, especially the complete replacement of fossil fuels with solar and wind. For that, the grid would need enough stored electricity to last for many hours in case weather patterns interfere with power generation at solar and wind farms, which is a frequent occurrence.
Utility-scale storage and EV batteries will seal the fate of the renewable revolution pretty much single-handedly. Falling costs of solar and wind technology are always good news, but without storage, these falling costs are not really relevant for the long-term.
By Irina Slav for Oilprice.com
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