China connects world’s largest redox flow battery system to grid

This is only 0.4 GWh, going up to 0.8 GWh.

Globally, to completely replace fossil fuels we will need on the order of 1 PWh.

It's early days still. Far too early to be picking winners. There are dozens of storage technologies being experimented with, each having advantages and disadvantages, niches and no-go areas.