Many companies have been trying to make solid state batteries for years but it's hard to make anything that works at scale as opposed to some 2mm sample on a lab bench. I guess the likes of BYD got there first because they have put a lot of investment dollars and engineers in, being the world's second largest battery maker. I think CATL the largest are also working on it. And Toyota. I'm not sure any have been able to manufacture in quantity at an acceptable price though. Soon probably.