Tesla Model S has a big 'ol slab of batteries that make up the floor of the thing, shown above, but Tesla CEO Elon Musk says that sort of technology just won't do in the long run. He thinks that the days of the battery are numbered, and that it's the humble capacitor that will "supercede" traditional cells and let our future selves roam wild in our Teslas, largely free of range anxiety. Ultracapacitors are basically big, powerful versions of the capacitors that make all electronics work. Like a battery they hold a charge, but unlike a battery they can be juiced up almost instantaneously and suffer virtually no degradation through cycle after cycle. The big problem now is energy density, where batteries still have their capacitive competition beat, but hopefully that'll change soon -- maybe in time for another of Musk's predictions to come true.