Vanadium flow batteries have gotten lots of interest because vanadium has 4 oxidation states, so the positive and negative electrolyte tanks have distinct charg

Vanadium flow batteries have gotten lots of interest because vanadium has 4 oxidation states, so the positive and negative electrolyte tanks have distinct charged and discharged chemistries. This adds a ton of flexibility to usage from multiple cycles per day to seasonal storage while the battery is still operating daily. Manufacturers are advertising 20k cycles vs 6-7k for Li-ion, but in theory, flow batteries can last forever with maintenance.