I’m still a novice on the material science behind it, but what is QuantumScape lacking here if anything, and why is it a dealbreaker?
Perhaps a polymer will be invented that can’t be pierced by dendrites. But existing polymers need to be heated for ion transfer efficiency and are combustable.
Technically, QuantumScape also uses an organic liquid catholyte inside the cathode. So it’s not “pure” solid state.