A New Idea for Low-Price Batteries – Made From Cheap, Plentiful Supplies

An aluminum-sulfur battery, created from cheap, plentiful supplies, may present low-cost backup storage for renewable power sources.

As ever bigger installations of wind and solar energy techniques are being constructed around the globe, the necessity is rising quick for economical, large-scale backup techniques to offer energy when the the air is calm and solar is down. As we speak’s lithium-ion batteries are nonetheless too costly for many such functions. Different choices resembling pumped hydro require particular topography that’s not at all times obtainable.

Now, scientists at MIT and elsewhere have developed a brand new form of battery, made completely from plentiful and cheap supplies, that would assist to fill that hole.

The brand new battery structure, which makes use of aluminum and sulfur as its two electrode supplies, with a molten salt electrolyte in between, is described at this time (August 24, 2022) within the journal Nature. The paper was written by MIT Professor Donald Sadoway, together with 15 others at MIT and in China, Canada, Kentucky, and Tennessee.

“I wished to invent one thing that was higher, significantly better, than lithium-ion batteries for small-scale stationary storage, and finally for automotive [makes use of],” explains Sadoway, who’s the John F. Elliott Professor Emeritus of Supplies Chemistry.

Moreover for being costly, lithium-ion batteries include a flammable electrolyte, making them lower than ultimate for transportation. Due to this fact, Sadoway began finding out the periodic desk, searching for low-cost, Earth-abundant metals which may have the ability to substitute for lithium. Iron, the commercially dominant steel, doesn’t have the appropriate electrochemical properties for an environment friendly battery, he says. Nevertheless, the second-most-abundant steel within the market — and truly essentially the most plentiful steel on Earth — is aluminum. “So, I mentioned, nicely, let’s simply make {that a} bookend. It’s gonna be aluminum,” he says.

The three main constituents of the battery are: left, aluminum; heart, sulfur; and proper, rock salt crystals. All are domestically obtainable Earth-abundant supplies not requiring a worldwide provide chain. Credit score: Rebecca Miller

Then got here deciding what to pair the aluminum with for the opposite electrode, and what sort of electrolyte to place in between to hold ions backwards and forwards throughout charging and discharging. The most affordable of all of the non-metals is sulfur, in order that grew to become the second electrode materials. As for the electrolyte, “we weren’t going to make use of the unstable, flammable natural liquids” which have typically led to harmful fires in automobiles and different functions of lithium-ion batteries, Sadoway says. They tried some polymers however ended up taking a look at quite a lot of molten salts which have comparatively low melting factors — near the boiling level of water, versus practically 1,000 levels Fahrenheit (538 degrees Celsius) for many salts. “Once you get down to near body temperature, it becomes practical” to make batteries that don’t require special insulation and anticorrosion measures, he says.

The three ingredients they ended up with are cheap and readily available. First is aluminum, no different from the foil at the supermarket. Second is sulfur, which is often a waste product from processes such as petroleum refining. And finally, widely available salts. “The ingredients are cheap, and the thing is safe — it cannot burn,” Sadoway says.

In their experiments, the team showed that the battery cells could endure hundreds of cycles at exceptionally high charging rates, with a projected cost per cell of about one-sixth that of comparable lithium-ion cells. They showed that the charging rate was highly dependent on the working temperature, with 110 degrees Celsius (230 degrees Fahrenheit) showing 25 times faster rates than 25 °C (77 °F).

Surprisingly, the molten salt the team chose as an electrolyte simply because of its low melting point turned out to have a fortuitous advantage. One of the biggest problems in battery reliability is the formation of dendrites, which are narrow spikes of metal that build up on one electrode and eventually grow across to contact the other electrode, causing a short-circuit and hampering efficiency. But this particular salt, it happens, is very good at preventing that malfunction.

The chloro-aluminate salt they chose “essentially retired these runaway dendrites, while also allowing for very rapid charging,” Sadoway says. “We did experiments at very high charging rates, charging in less than a minute, and we never lost cells due to dendrite shorting.”

“It’s funny,” he says, because the whole focus was on finding a salt with the lowest melting point, but the catenated chloro-aluminates they ended up with turned out to be resistant to the shorting problem. “If we had started off with trying to prevent dendritic shorting, I’m not sure I would’ve known how to pursue that,” Sadoway says. “I guess it was serendipity for us.”

Moreover, the battery requires no external heat source to maintain its operating temperature. The heat is naturally produced electrochemically by the charging and discharging of the battery. “As you charge, you generate heat, and that keeps the salt from freezing. And then, when you discharge, it also generates heat,” Sadoway says. In a typical installation used for load-leveling at a solar generation facility, 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.”

This new battery formulation, he says, would be ideal for installations of about the size needed to power a single home or small to medium business, producing on the order of a few tens of kilowatt-hours of storage capacity.

For larger installations, up to utility scale of tens to hundreds of megawatt hours, other technologies might be more effective, including the liquid metal batteries Sadoway and his students developed several years ago and which formed the basis for a spinoff company called Ambri, which hopes to deliver its first products within the next year. For that invention, Sadoway was recently awarded this year’s European Inventor Award.

The smaller scale of the aluminum-sulfur batteries would also make them practical for uses such as electric vehicle charging stations, Sadoway says. He points out that when electric vehicles become common enough on the roads that several cars want to charge up at once, as happens today with gasoline fuel pumps, “if you try to do that with batteries and you want rapid charging, the amperages are just so high that we don’t have that amount of amperage in the line that feeds the facility.” So having a battery system such as this to store power and then release it quickly when needed could eliminate the need for installing expensive new power lines to serve these chargers.

The new technology is already the basis for a new spinoff company called Avanti, which has licensed the patents to the system, co-founded by Sadoway and Luis Ortiz ’96 ScD ’00, who was also a co-founder of Ambri. “The first order of business for the company is to demonstrate that it works at scale,” Sadoway says, and then subject it to a series of stress tests, including running through hundreds of charging cycles.

Would a battery based on sulfur run the risk of producing the foul odors associated with some forms of sulfur? Not a chance, Sadoway says. “The rotten-egg smell is in the gas, hydrogen sulfide. This is elemental sulfur, and it’s going to be enclosed inside the cells.” If you were to try to open up a lithium-ion cell in your kitchen, he says (and please don’t try this at home!), “the moisture in the air would react and you’d start generating all sorts of foul gases as well. These are legitimate questions, but the battery is sealed, it’s not an open vessel. So I wouldn’t be concerned about that.”

Reference: “Fast-charging aluminium–chalcogen batteries resistant to dendritic shorting” by Quanquan Pang, Jiashen Meng, Saransh Gupta, Xufeng Hong, Chun Yuen Kwok, Ji Zhao, Yingxia Jin, Like Xu, Ozlem Karahan, Ziqi Wang, Spencer Toll, Liqiang Mai, Linda F. Nazar, Mahalingam Balasubramanian, Badri Narayanan and Donald R. Sadoway, 24 August 2022, Nature.
DOI: 10.1038/s41586-022-04983-9

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; Oak Ridge National Laboratory, in Tennessee; and MIT. The work was supported by the MIT Energy Initiative, the MIT Deshpande Center for Technological Innovation, and ENN Group.