We have fusion, 1 AU away. Utility PV gives us an EROEI or around 11. That's good enough, such that a focus on storing the output trumps the development of more abundant local production.
Not so much batteries, but "energy storage" in general. Batteries being one very important type of energy storage.
If photovoltaics and/or wind become extremely cheap, to the point where the cost is 1 cent/kilowatt-hour, it would even be economical to crack hydrogen from seawater via electrolysis (a process that consumes vast amounts of electricity) and use hydrogen as storage.
