Correct. Fuel cell is for electric generation, not electric storage.
So is a lithium-ion battery. Or any other type of battery. A fuel cell is really just another type of battery. All of them produce electricity electrochemically.
If you actually aim to store electricity as electricity, you want a capacitor. Recently, so-called supercapacitors have been developed, which are capable of storing useful amounts of energy, but they're starting to blur the line between electric and chemical storage, e.g., pseudocapacitors.