Please excuse me if I am terribly ignorant. In my head, liquid must be easier to play with than a solid. So displacement of water or air should be done. The

Please excuse me if I am terribly ignorant. In my head, liquid must be easier to play with than a solid. So displacement of water or air should be done. The displacement of air, being pumped into a balloon under water seems like a great idea. I know many solutions must have been thought of, but is the inflate balloon under water , then let it float up - the most efficient way of storing energy? Lithium batteries wear out, but are more energy dense and so arent comparable ( regardless of size). Forgive me for ruminating I think this is a problem with an already identified solution though?