For grid-storage they may very well be… https://en.wikipedia.org/wiki/Iron_redox_flow_battery
is e.g. in place in Sacramaneto, CA with a storage of 2 GWh and a maximum power of 200 MW.
For grid-storage durability and ovrerall cost efficiency are more important than energy density so I expect redox flow batteries to overtake lithium ion based batteries there.
For grid-storage they may very well be…
https://en.wikipedia.org/wiki/Iron_redox_flow_battery
is e.g. in place in Sacramaneto, CA with a storage of 2 GWh and a maximum power of 200 MW.
For grid-storage durability and ovrerall cost efficiency are more important than energy density so I expect redox flow batteries to overtake lithium ion based batteries there.