Regeneration of flow battery electrode

A flow battery comprising:

• at least one cell including a first electrode, a second electrode spaced apart from the first electrode, and an electrolyte separator layer arranged between the first electrode and the second electrode;
• a supply/storage system external of the at least one cell and including:
• a first vessel fluidly connected in a first loop with the first electrode,
• a second vessel fluidly connected in a second loop with the second electrode, the first loop and the second loop being isolated from each other with respect to open fluid flow there between;
• and
• a controller that is configured to regenerate catalytically active surfaces of one of the first electrode or the second electrode during shutdown of the flow battery from an active charge/discharge mode to an inactive, shut-down mode in which neither a negative electrolyte nor a positive electrolyte are circulated through the at least one cell, by driving voltage of the least one cell toward zero by converting, in-situ, the negative electrolyte in the at least one cell to a higher oxidation state, the negative electrolyte in contact with one of the first electrode or the second electrode, and using the higher oxidation state negative electrolyte to regenerate, in-situ, the catalytically active surfaces of the electrode.