It really is technology in it's infancy.
And a battery isn't necessary what you think it is. Pumped hydro is a battery. During the day with the excess energy you use it to pump the water back to the top.
Yes pumped Hydro is great. But very capital intensive.
Chemical batteries aren't in their infancy.
It really is a limited technology.
Most of the future gains have "cars" in mind, so they are trying to advance weight, size, and charge time.
None of which is really the issue for power storage.