https://open.substack.com/pub/constructionphysics/p/why-is-everyone-trying-to-build-a
This is a good article to get a basic understanding of solid state batteries. It is not for the faint of heart, but rewards careful reading.
I think we are still in the early days of battery technology. Batteries serve a very useful purpose and will continue to do so. Lithium is having a great run, but others are on the horizon.
As long as there is money to be made, people will try to create something better. And there is a lot of money to be made in batteries.