But capacitors aren’t batteries. Batteries store chemical energy. Capacitors store electrical potential energy. Electronically they behave much differently.
That's what I do being off-grid. I have my battery bank then a series of Supercaps to essentially act as an on/off ramp//drawbridge and temper quick demands. Kinda like an inverse soft starter so this is suuuuper interesting to me.
Only for certain types of capacitors. In practice they can overlap quite a bit, especially with common aluminium electrolytic capacitors (these form & dissolve complex aluminium oxide & hydroxide layers on the plates).
Headline is not dumb. There are reasons to make a distinction between the two, the most salient one being that capacitors are several orders of magnitude faster to charge and discharge.
However the galvanic potential of lithium is as large as is practically possible. The galvanic potential is what really matters for a battery. Capacitors are nowhere near the joules per weight/volume.