Solid state batteries are something different. Both Lithium and Sodium can be used for them - Lithium has better density, but again Sodium is cheaper. Sodium on

Solid state batteries are something different. Both Lithium and Sodium can be used for them - Lithium has better density, but again Sodium is cheaper. Sodium ones are still being researched, but eventually can be 2-3x energy denser than current Lithium Ion.