MIT has shown that dendrites (The bane of solid state Lithium Ion batteries) can be controlled. The control is mechanical pressure and the pressure can be applied in multiple ways.
This should allow for the construction of a truly workable solid state battery. There may be more fall out from this discovery and the method that made the discovery possible .
While this is late in the game per my predicted time line for EV/ICE cost parity at 2025 (No subsidies) There are people gearing up to make solid state lithium ion pouch solid state batteries now. They have other but less effective ways of controlling dendrite growth. This discovery should allow them to make slight adjustments to their manufacturing process and make even better lighter batteries.
Cheers
Qazulight