https://formenergy.com/technology/battery-technology/ https://formenergy.com/technology/battery-technology/ Last figure I saw was 1/4 the cost of Li batteries.

https://formenergy.com/technology/battery-technology/ https://formenergy.com/technology/battery-technology/ Last figure I saw was 1/4 the cost of Li batteries. (I guess lithium cells have got cheaper since they made that page.)