Fission is too expensive. The good real reasons from a cost perspective for reactors are weapons, medical and industrial applications as well as research.

Why would you want to use battery storage instead of pressure or gravity, for example? You can do gravity by moving stuff around underground, not just classical pumped storage. Digging big and deep holes is something people know how to do quite well, same goes for moving weights/mass up and down.

Could also do some chemical storage as another avenue.

For heat you can have certain thermal storage, too.