They don't just need to work, they need to be economically viable.

These batteries have active components, since they actually pump the electrolyte, and there's a fairly substantial level of degradation and corrosion, along with leaking across the membrane that leads to loss of capacity over time.

If some of these problems can be reduced (like the article claims they do) then they're even more attractive.

I really hope this helps with massively expanding renewables storage, because that's bastion holding up fossil fuels in electricity generation, and it will allow shutting down all those coal, gas, even nuclear plants!