I was poking around in Yahoo Finance, and ran across ESS Tech $GWH.
They make an Iron Redox Flow Battery, which might be an alternative to Li-Ion for large scale energy storage.
Main advantage is 10,000+ cycle life
Main disadvantage, is extremely bulky, unlikely to replace small size batteries.

There is also vanadium redox flow battery. Has been arounf 90+ years, but V is expensive and also fairly toxic, especially compared to Fe.

Anyone done any further research on this? Any recommendations?

Some links I found.
https://essinc.com/wp-content/uploads/2021/09/ESS_OnePager_FINAL_9-14-21.pdf
https://en.wikipedia.org/wiki/Iron_redox_flow_battery
ARPA project; https://arpa-e.energy.gov/technologies/projects/iron-flow-battery
https://www.blackridgeresearch.com/blog/top-flow-battery-companies-manufacturers

Edit to add symbol.

The new kid on the block in the solar generator battery system is the Lithium Iron Phosphate battery. Much safer than lithium ion and up to 15,000 recharges as opposed to around 3500. A bit heavier.

Nice revenue growth on that one.

The big knock on iron batteries from what I understand is they are not as robust as lithium. But they're a lot cheaper.