For peak storage, vanadium accumulators are well established. Lithium cells give you an advantage in density, but for peak storage you are looking at capacity

For peak storage, vanadium accumulators are well established. Lithium cells give you an advantage in density, but for peak storage you are looking at capacity first, and then you consider the footprint. With vanadium you are only limited by the size of your electrolyte tank. The additional advantage is that vanadium reserves are much greater than lithium reserves.