A redox flow battery comprising: an ionically conductive separator comprising a working side and a counter side; a working side flowing electrolyte; a working electrode in ionic contact with the working side of the ionically conductive separator and the working side flowing electrolyte; a counter side flowing electrolyte; a counter electrode in ionic contact with the counter side of the ionically conductive separator and the counter side flowing electrolyte; an auxiliary electrode peripherally circumscribed by the working electrode in a common layer of the flow battery, wherein the auxiliary electrode is in ionic contact with the working electrode, the working side flowing electrolyte, and the working side of the ionically conductive separator; an electrically insulating peripheral gap separating the auxiliary electrode from the working electrode; a working electrode terminal conductively coupled to the working electrode; an auxiliary electrode terminal conductively coupled to the auxiliary electrode; a counter electrode terminal conductively coupled to the counter electrode; and an auxiliary power source electrically connected to the auxiliary electrode terminal and the counter electrode terminal, wherein the auxiliary power source is configured to establish an auxiliary circuit voltage differential between the counter electrode terminal and the auxiliary electrode terminal, control an auxiliary electrode voltage such that the auxiliary electrode voltage is within an electrochemical window of the working side flowing electrolyte, and establish a voltage differential between the working electrode terminal and the auxiliary electrode terminal. an ionically conductive separator comprising a working side and a counter side; a working side flowing electrolyte; a working electrode in ionic contact with the working side of the ionically conductive separator and the working side flowing electrolyte; a counter side flowing electrolyte; a counter electrode in ionic contact with the counter side of the ionically conductive separator and the counter side flowing electrolyte; an auxiliary electrode peripherally circumscribed by the working electrode in a common layer of the flow battery, wherein the auxiliary electrode is in ionic contact with the working electrode, the working side flowing electrolyte, and the working side of the ionically conductive separator; an electrically insulating peripheral gap separating the auxiliary electrode from the working electrode; a working electrode terminal conductively coupled to the working electrode; an auxiliary electrode terminal conductively coupled to the auxiliary electrode; a counter electrode terminal conductively coupled to the counter electrode; and an auxiliary power source electrically connected to the auxiliary electrode terminal and the counter electrode terminal, wherein the auxiliary power source is configured to establish an auxiliary circuit voltage differential between the counter electrode terminal and the auxiliary electrode terminal, control an auxiliary electrode voltage such that the auxiliary electrode voltage is within an electrochemical window of the working side flowing electrolyte, and establish a voltage differential between the working electrode terminal and the auxiliary electrode terminal.