Battery storage capacity is limited by the battery device itself and is subject to various kinds of decay over time.
Fuel cells on the other hand are the only high-tech component in the system while the hydrogen can be stored in bulk.
Certainly, hydrogen storage does have its own difficulties, but they don't require nanomaterials or precious metals to solve.
The only batteries that provide similar properties are redox flow batteries, which happen to be quite similar to fuel cells.
