Thursday, July 20, 2023

Sulphur-selenium solid state battery



There is a ferment of new and advancing technology in batteries. Some will go on to be commercially successful; others will not.



From CleanTechnica



Most of us have little idea what NASA — the National Aeronautics and Space Administration — has been doing since the Apollo moon missions ended. We know it is responsible for Tang and space blankets, but what has it done for us lately?

It turns out, the “aeronautics” part of its mission includes advances in airplanes, and that means finding alternatives to conventional fuels that will leave fewer emissions behind during flight. As any EV advocate knows, vehicles powered by batteries and electricity are far more efficient than conventional cars powered by last century internal combustion technology. But batteries are heavy and bulky — two words that aeronautical engineers never want to hear.

But what if batteries had two or three times more power than today’s best lithium-ion batteries? And what if they also had no liquid or semi-liquid electrolyte inside that could burst into flames? “Fire” and “airplane” are two words that should never be used in the same sentence.

The promise of battery-powered flight is very much on the minds of airline executives who are under pressure to slash emissions from their flights. It also fires the imagination of those who want to bring air taxis into commercial use. The latest news from NASA should be of interest to both groups.

For years, NASA has been researching battery-powered flight as part of its Solid-state Architecture Batteries for Enhanced Rechargeability and Safety program. “SABERS continues to exceed its goals,” said Rocco Viggiano, principal investigator for SABERS at NASA’s Glenn Research Center in Cleveland in a press release last year. “We’re starting to approach this new frontier of battery research that could do so much more than lithium-ion batteries can. The possibilities are pretty incredible.”

Viggiano says a battery is like a bucket that stores energy. More energy storage is like having a larger bucket. NASA says its sulfur selenium prototype battery has an energy density of 500 watt-hours per kilogram, which is about double that of conventional lithium-ion batteries.

But aircraft need enormous amounts of power to get off the ground. Until recently, lithium-ion batteries were able to discharge their stored power much more quickly than solid-state batteries could. Now the SABERS researchers, with help from partners at Georgia Tech, have found a way to make their solid-state batteries discharge ten times faster than when the research started. Then they achieved another five-fold increase after that. So now they have a larger bucket that can be emptied rapidly when needed.

That bucket is also up to 40% lighter because of more innovations discovered by the SABERS team. Their sulfur selenium battery cells can be stacked one on top of the other with no casing around them. Eliminating the casing around individual cells means more energy storage within a given amount of space — a huge advantage when trying to fit batteries into the structure of an aircraft. It also means the cooling systems for the cells can be smaller and lighter.

There are other advantages as well. The massive amounts of energy needed at the beginning of any flight can cause temperatures inside battery cells to spike. The solid-state sulfur selenium batteries from NASA are able to withstand temperatures twice as hot as conventional lithium-ion batteries. In addition, they are less affected by changes in pressure, which occur rapidly after takeoff and while landing. So far, it’s all good news for electric flight advocates.

Are there any drawbacks? Cost is a big factor. And the testing protocols before new components get approved for use in commercial aircraft are far more rigorous than they are for ordinary vehicles.





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