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.
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.