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Aluminum, sulfur and salt, MIT’s recipe for cheaper and safer batteries than lithium batteries

In recent years, lithium batteries have become ubiquitous in our lives, and we find them in all kinds of devices, from cell phones to electric cars. But, as is known, the inevitable result of lithium shortage is its price increase. Additionally, the cells in these batteries can explode or burn if damaged or misused.

Researchers at MIT (Massachusetts Institute of Technology) and other US, Chinese, and Canadian laboratories seem to have found an alternative to lithium that avoids all of the described drawbacks and, at the same time, can match lithium in terms of reliability and density. energy. The recipe they found couldn’t be simpler and cheaper, based on aluminum, sulfur and salt, a very common material in nature and therefore very cheap.

The aluminum needed to produce this new battery is no different from the battery making aluminum foil that we can buy at the supermarket. Sulfur is an abundant waste product in industrial processes such as oil refining, and the salts are “widely available,” as MIT itself notes. Professor Donald Sadoway, who led the research – published in the journal ability– he sums up almost jokingly: “The ingredients are cheap and the stuff is safe, it doesn’t burn.”

In their experiments, the team showed that the cells in the new device can withstand hundreds of charge and discharge cycles, and that they also support rapid charging, which was achieved in less than a minute in some tests. Thanks to this chemical configuration, when this class of cells can be produced on a large scale, the cost of a battery equipped with this technology will be reduced to a sixth of that of a lithium battery of similar size.

Sedowway and his team set to work looking for a replacement for lithium, using the periodic table to find a replacement for the cheapest and most abundant metals on Earth. Because iron, which is commercially dominant, lacks the proper electrochemical properties for an efficient battery, they turned their attention to aluminum, the second most abundant metal on the market and, in fact, the most abundant metal on our planet.

For the other electrode, they chose the cheapest of all nonmetals, sulfur, and for the electrolyte, which was supposed to move ions back and forth during charging and discharging, they decided on various molten salts that have relatively low melting points. to the boiling point of water.

As the tests showed, the new cells could not only work at a high temperature, up to 200 degrees, but they did it optimally from 110 degrees. In fact, charging at this temperature was 25 times faster than at 25°.

In addition, Sadoway et al.’s battery does not require an external heat source to maintain its operating temperature. Heat is naturally produced electrochemically by charging and discharging the device itself. “As you load, you generate heat and that prevents the salt from freezing. And then when you discharge, it also generates heat,” explains the professor.

unintended benefits

As if that weren’t enough, the molten salt chosen as the electrolyte had the added advantage of its low melting point: it prevented the formation of dendrites, the narrow metal spikes that collect on the electrode and degrade the battery’s performance. .

The researchers say this battery design is well-suited to capacities of “several tens” of kWh, just what is needed to power an electric car or home.

They can also be ideal as car charging stations. Sadoway says that when EVs become so common on the road that several of them want to be charged at the same time, as is the case today at gas stations, “very high amperages are required to carry the line that feeds the installation. ” Therefore, having such a battery system to store energy and quickly release it when needed could eliminate the need to install expensive new power lines for these chargers.

For large installations on cars or homes that require tens of megawatt-hours, other technologies may be more efficient, such as the liquid metal batteries that Sedoway himself and his students developed a few years ago, and for which he received an MIT professorship emeritus. European Inventor of the Year Award.

Meanwhile, the aluminum-sulfur battery is already the basis of a new spin-off company called Avanti, which has licensed the system’s patents. “The first order of business for a company is to prove that it works at scale,” Sadoway concludes, and then runs a series of stress tests, including running hundreds of load cycles.

Source: El Diario





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