Pumped Hydro Energy Storage across Australia, page-123

Sure, I think the capacitor hybrid does a job. I'd expect that the capacitor hybrid improves the load cycling impact on the battery.

The only thing I have a problem with is that at grid scale - say 100MW+ sort of size, and looking for hours of capacity. Everything I've read says that flow batteries will do that cheaper than Li, or Li-hybrids, or lead acid, hybrids included.

My presumption/view is that in most countries there is still enough hydro/gas/thermal and interconnection to firm the amount of renewables already on the system, and the amount expected for a few more years. And we're (speaking globally) not quite ready to simply ditch existing thermal plant that has economic life left, until something very cost competitive comes along. So the urgency and commercial demand for large scale flow batteries isn't quite there yet. And hence most of the work is still research and development, price and performance and, to your point, reliability improvement, ready to pick winners and commercially scale up. But I'm not in that industry and that's just my reading between the lines.