A redox flow battery and a method of operating a redox flow battery. The redox flow battery includes an ionically conductive separator, a working side flowing electrolyte, a working electrode, a counter electrode, and an auxiliary electrode. The auxiliary electrode is in ionic contact with the working electrode, where an electrically insulating peripheral gap separates the auxiliary electrode from the working electrode. An auxiliary power source is configured to establish an auxiliary circuit voltage differential between a terminal in each of the counter electrode and the auxiliary electrode to control an auxiliary electrode voltage such that the auxiliary electrode voltage is within an electrochemical window of the working side flowing electrolyte, as well as to establish a voltage differential between the working electrode terminal and the auxiliary electrode terminal.