Contact angle measuring machine for ball bearings

Redux flow cells have had nowhere near the R+D effort compared to Lithium ion. They certainly have the potential (pun not intended) for longer...

EV battery weighs typically between half and three-quarters of a tonne. Hope the suitcase has a strong handle

This is all about cost/energy density. Just work out how big a mechanical system would be compared to the flow battery. Unfortunately there is not...