Aluminum, sulfur, salt. Common, everyday items. They may be the basis for low-cost electric battery storage, supplanting expensive lithium-ion technology. If so, they could provide a low-cost way to store intermittent renewable electricity from wind and sun, using abundant, domestically available material.
In an article published last August in the journal Nature, 16 researchers from the U.S., China, and Canada have proposed a battery technology that uses aluminum and sulfur as electrodes and molten salt as the electrolyte. The article describes “a bidirectional, rapidly charging aluminium–chalcogen [sulfur, one of five chalcogen elements – Ed.] battery operating with a molten-salt electrolyte composed of NaCl–KCl–AlCl,” a low-temperature molten salt, operating at around 110C.
The paper says the chemistry of the theoretical battery offers “rapid charging at up to 200C, and the battery endures hundreds of cycles at very high charging rates…. Importantly for scalability, the cell-level cost of the aluminium–sulfur battery is projected to be less than one-sixth that of current lithium-ion technologies.”
The researchers assert, “Composed of earth-abundant elements that can be ethically sourced and operated at moderately elevated temperatures just above the boiling point of water, this chemistry has all the requisites of a low-cost, rechargeable, fire-resistant, recyclable battery.” In short, it overcomes problems inherent in the now-dominant Li-ion technology, which is expensive, not recyclable, and can catch fire relatively easily.
MIT materials chemist and battery expert professor emeritus Donald Sadoway, a lead researcher on the project, in an MIT press release said that the battery doesn’t need external heat to keep the electrolyte salt molten. “As you charge, you generate heat, and that keeps the salt from freezing,” he said. “And then, when you discharge, it also generates heat.” In a solar installation, for example, “you’d store electricity when the sun is shining, and then you’d draw electricity after dark, and you’d do this every day. And that charge-idle-discharge-idle is enough to generate enough heat to keep the thing at temperature.”
One aspect of the technology that some might consider a problem and others might see as an advantage is size. According to Sadoway, the batteries, with tens of KWh of capacity, would be best for backup power for a single home or a small business, not utility scale applications. On the other hand, aluminum-sulfur batteries could be good for EV charging stations, with groups of the batteries providing distributed amperage, eliminating the need for new power lines to serve conventional chargers.
What’s next for the aluminum-sulfur battery? Sadoway has started a company, Avanti (Italian for “forward”), headquartered in Watertown, Mass., to work on commercial development. ““The first order of business for the company is to demonstrate that it works at scale,” and then subject it to rigorous stress testing, he says.
In addition to MIT, the research team included members from Peking University, Yunnan University, and the Wuhan University of Technology in China; the University of Louisville, in Kentucky; the University of Waterloo, in Canada; Argonne National Laboratory, in Illinois.
In other battery news:
Japanese car company Nissan says it plans to roll out solid state batteries for its EVs in 2028. The batteries will be lighter, less ensive, and charge faster than current Li-ion technology, the company claims. In an interview in the British publication Autocar, David Moss, Nissan’s European head of research and development, said the company is still on track to hit its 2028 production target. “We think we have something quite special and are in a group leading the technology,” Moss told Autocar. “We want to get the cost down [compared to lithium-ion batteries] by 50 percent, to double the energy density and to offer three times the charging speed.”
Finland paper producer Stora Enso and Swedish EV company Polestar are collaborating to develop what they call “a truly climate-neutral car by 2030. Stora Enso joins Polestar 0 project as a partner to contribute to the car’s climate neutrality with their bio-based battery material Lignode® by Stora Enso, made from trees.” The BBC reports that the tree-produced polymer lignin, rich in carbon, and a forest industry waste product, could be used to make carbon anodes, the negative terminals, in EV batteries. Lauri Lehtonen, head of Stora Enso’s lignin-based battery solution, Lignode, told the BBC, “Lignin is the glue in the trees that kind of glues the cellulose fibres together and also makes the trees very stiff.”
–Kennedy Maize
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