system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If a battery stores power in chemical reactions and supercapacitors store power as charge, what is the key enabler that is now making solid state batteries practical, and how is this different from high-discharge batteries or supercapacitors?
gpt
The innovation is a ceramic layer that sits between the cathode and anode and is what puts the "solid" in "solid state" (as opposed to a non-solid separator).  This layer ferries lithium ions from one terminal to another, and critically stops the formation of lithium dentrites (tiny metal spikes that form when lithium batteries charge) from connecting the two sides of the battery and forming short circuits.  This working ceramic layer is the new tech that makes the solid state battery practical.