We can indeed use things like pump storage and gravity batteries, but we don't really have to. The next element down on the periodic chat from lithium can be used in place of lithium at half the energy density. Which to save you time, it's sodium, which can be found in salt, which we have quite a bit of on the planet.

Sodium ion batteries were slightly researched but lithium got the money because it has twice the energy density (amount of energy you can store per kilogram). However, for giant batteries that never have to move, sodium ion batteries are ideal for grid storage.