This is my favourite tech as its cheap and safe: https://en.wikipedia.org/wiki/Iron_redox_flow_battery https://en.wikipedia.org/wiki/Iron_redox_flow_battery I

This is my favourite tech as its cheap and safe: https://en.wikipedia.org/wiki/Iron_redox_flow_battery https://en.wikipedia.org/wiki/Iron_redox_flow_battery Its commercially available right now as well. Its not as efficient as lithium or as energy dense, but that doesnt matter if you're putting them in wind/solar farms.