Batteries can solve short term (days to a week at most) storage problems, they don't solve seasonal storage problems - making sure you have enough energy all the way through a cold, not very sunny, and not consistently windy winter.

If you don't believe me, run the numbers of how many kg of lithium batteries China would need to supply an entire week of energy in the middle of winter (all energy, not just current electricity demand, because in this scenario we're assuming everything is 100% electrified).

Also if you're potentially going to be fighting a war, you need more energy, not less, and it's even more important for it to be reliable year-round.

This is why China is doing what they're doing, they're not idiots and they know that wishful thinking is not a strategy