I think an analogy with electric vehicles might make things a...

I think an analogy with electric vehicles might make things a bit clearer. fuel cell vehicles and battery vehicles both drive electric motors. fuel cells can't supply the responses for rapid acceleration, a Li battery can. fuels cells do have the potential to provide a superior range than batteries. so some manufacturers (although fuel cells for various reasons are out of favour at present), have a small capacity lithium battery to provide the surge capability for rapid acceleration. couldn't a hybrid flow/ li battery do the same for the grid and provide longer term storage? This is not new, but doesn't appear to be considered, much like fuel cells/ battery have lost ground in the automotive world.