So I take it you are not enthused about the work being done with Graphene which I believe puts it in the category of an Ultra Capacitor? I see some Graphene websites with PHD types experimenting with Silica and Tungsten DiSulfide in combination with the Graphene...
My enthusiasm is also tempered by watching the evolution of the next thing to replace the magnetic disk drive. There was SOS, Magnetic bubbles, optical, magneto-optic and a host of others. Now flash may do the job, or the boffins at IBM will pull another order of magnitude increase in density out of their nether regions. I don't know where the smart money is today, but I do know where it has been.
Technology is hard. 9 out of 10 good ideas don't pan out as successful companies. And remember, these things are not sources of energy, merely really cool gas tanks.
Fight the Free Sh☭t Nation