Batteries exist yes. But batteries at the scale required to store the amount of energy that even a small country uses in one day do not exist, and would be by all accounts magic.
Nuclear reactors are not magic, they are real, and they can be built, and should be built both to increase our energy production and replace fossil fuels and of course supplement renewables. Because if nuclear reactors are not built, that supplemental energy won't come from magic storage, it will come from fossil fuels.