Redox flow battery and method of operating the same

A redox flow battery in which a positive electrode electrolyte stored in a positive electrode tank and a negative electrode electrolyte stored in a negative electrode tank are supplied to a battery element including a positive electrode, a negative electrode, and a membrane interposed between these electrodes, to charge and discharge the battery,

• said positive electrode electrolyte containing a Mn ion as a positive electrode active material,
• said negative electrode electrolyte containing at least one of a Ti ion, a V ion, and a Cr ion as a negative electrode active material,
• said redox flow battery comprising:
• a negative-electrode-side introduction duct in communication with inside of said negative electrode tank from outside thereof, for introducing oxidizing gas into said negative electrode tank;
• and
• a negative-electrode-side supply mechanism for supplying said oxidizing gas into said negative electrode tank via said negative-electrode-side introduction duct.