Energy storage depends on the electromotive potential (i.e. difference between species in the electromotive series) and on the number of electrons available.
Li, for example, has an oxidation potential of ~3.04 V relative to hydrogen, but Al has one of 1.66 V, so Li has the greater potential. On the other hand, Li has only one freely available outer electron, but Al has three, so Al stores more charge per mol, giving three times the capacity in coulombs on that basis. On the gripping hand, however, Li has a mass of ~7 amu, and Al is ~27 amu, so an aluminum cell carries around the dead weight of unused neutrons and inner electron/protons.
So, depending on the needs, Li batteries weigh relatively little and provide comparatively high potential, aluminum batteries would hold more charge at a bit lower voltage, and even Zn is useful, though deficient compared to those others in volts and coulombs (it also has a bunch of inert neutrons, but there is no charge for them), because it is relatively inexpensive.