Tuesday, October 13, 2015

Move Over, Lithium!

Over the past twenty years, as more and more technology has become incorporated into our daily lives, we’ve become increasingly reliant on the little lithium-ion miracles that keep our gadgets running while we’re on the run. Laptops, smartphones, electric vehicles—if it makes the modern world feel futuristic, it probably uses a rechargeable battery. While that’s not likely to change any time soon, the technology inside is about eighty years overdue for an overhaul: research from Oregon State indicates that lithium’s reign as the end-all of battery technology could soon be coming to an end. The next big thing? Potassium.
Although it’s one of the lightest elements on the periodic table, lithium isn’t very abundant in nature. In fact, its scarcity is downright weird: cosmological calculations predict higher levels of lithium in old stars than what we actually observe, implying that it gets destroyed before a star would have the chance to reach supernova stage and scatter it out into the universe. One of the most widely-cited objections to the movement toward electric vehicles is the idea that we’re just exchanging one unsustainable fuel technology for another. “What will we do,” came the cry, “when the lithium runs out?” Now, it’s starting to look like that question has an answer.

Virtually all battery cells are comprised of the same three components: a cathode at one end, an anode at the other, and conductive electrolyte fluid filling the space between them. In modern rechargeable batteries, the cathode and the anode are both made of porous, permeable materials, which can trap ions the way a sponge traps water, storing charge in the process. Historically, lithium has been seen as the best source for ions; its small stature means it can penetrate and diffuse through the anode more readily, offering a high energy density and a fast charge time. Alternative ion sources, like sodium and potassium, have long been thought unworkable or impractical, but a paper recently published in the Journal of the American Chemical Society turns that notion on its head by demonstrating a potassium-based battery cell that functions in much the same way as its lithium-ion counterpart.

While it’s not likely that potassium will supersede its lighter cousin in terms of pure energy density, its relative abundance makes it an attractive candidate for consumer technologies in the near future. Lithium is hard to come by and noxious to refine, and as global demand for battery-based technology grows, a potassium-ion alternative might become the economically viable choice for things like cell phone batteries.

It remains to be seen if the technology is truly as promising as Oregon State’s press release makes it seem, but the result is nonetheless noteworthy, if only as a reminder that constant questioning—even of the things that “everybody knows”—is crucial to scientific advancement. 

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