Actually exciting battery tech that isn’t just fluff. They actually built the thing and tested it, rather than it being a theoretical, not-easily-produced thing and it worked.
As others have said, this is for grid-scale and not EVs, but still exceptional progress and very important for energy storage.
I’m all for Sodium batts in cars, but my understanding is this battery tech is a different chemical composition than other Sodium Ion batteries. Most of those are not solid state AFAIK.