system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are these new-age solid-state batteries? How are they different from conventional batteries?
gpt
They're batteries that use solid electrodes or electrolytes instead of liquid.

They have potentially higher energy density, and are safer since they're not flammable. They also have longer lifespans and don't produce as much heat.

I think the problem at the moment is that they're not ready to be mass produced and so they're expensive.