The problem is that this is another "we totally have a solid state battery, honest" claim. We've been seeing this claim for at least last half a decade. They are universally followed by "no details on actual battery chemistry, and absolutely nothing on the solid electrolyte".
If the claimed "solid state" battery ever makes it into public's hands (most never do), someone cuts it open and universally, every single time we found liquid electrolyte inside.
The usual marketing spiel for that battery (if they even try to keep up the charade instead of just pivoting to "but our next one is solid state") is "well some parts of the battery have some parts that are sorta kinda solid sometimes, maybe, in very specific (non-operating) conditions, so we advertised it as solid state which is totally not a lie but marketing".
We'll see how it goes in this case, but frankly if anyone is to crack this one, it's probably going to be CATL. They threw everything and a kitchen sink at the problem with nearly limitless supply of money both from government "strategic industry" funding in PRC and profits (CATL is basically the only meaningfully profitable part of PRC's EV sector, it's profits comfortably exceed entire rest of EV automotive sector in PRC combined).
They have announced their one over three years ago, and it's been permanently stuck in "testing phase" ever since:
https://www.catl.com/en/news/6...
So take all these amazing battery claims with a boatload of salt.