Also the minor issue that mechanical energy storage tends to require a lot of room for what can be quite limited capacity.Energy storage doesn't need to be fancy battery tech or even electrochemical. Mechanical methods are more than good enough (pumped hydro, pressurised air, etc). We don't need anything from China for this. The reason nobody has taken energy storage seriously in recent decades is not that it's difficult, it's because it didn't make much economic sense given the low prices of fossil fuels. Obviously that trade-off has changed.
Pumped storage is great, if you've got enough large lakes one at the top of a hill and one at the bottom (it tends to be extremely disruptive to the environment, usually requiring large areas to be flooded), pressurised air is good but requires very large pressure vessels to do it (IIRC some countries with lots of nice mountains use tunnels dug into granite then lined), solid weight storage requires both a lot of space and either a lot of height or depth.
Battery tech has the advantage that it doesn't require specific geological conditions to do, and it's easier to maintain safely.