Abstract: A redox flow battery system comprising a catholyte in fluid communication with a cathode, an anolyte in fluid communication with an anode, a membrane in fluid communication with the catholyte and the anolyte, and positive and negative terminals in contact with a power supply and a load. The positive and negative terminals configured to charge the redox flow battery in an opposite direction such that the anolyte is oxidized and the catholyte is reduced. The anolyte and the catholyte are kept separate and never mixed.

Abstract: Devices and methods for managing the state of health of an electrolyte in redox flow batteries (RFB) efficiently are described. A diffusion cell is added to the RFB which controls one or more properties of the electrolytes using the diffusion of protons through a proton exchange membrane. The diffusion cell can resemble an electrochemical cell in that there are two fluid chambers divided by a proton conducting membrane. Anolyte flows through one side of the device where it contacts the proton conducting membrane, and catholyte flows through the second side of the device where it contacts the other face of the proton conducting membrane. The concentration gradient of protons from high concentration in the catholyte to low concentration in the anolyte is the driving force for proton diffusion, rather than electromotive force, which greatly simplifies the design and operation.

Abstract: Devices and methods for managing the state of health of an electrolyte in redox flow batteries (RFB) efficiently are described. A diffusion cell is added to the RFB which controls one or more properties of the electrolytes using the diffusion of protons through a proton exchange membrane. The diffusion cell can resemble an electrochemical cell in that there are two fluid chambers divided by a proton conducting membrane. Anolyte flows through one side of the device where it contacts the proton conducting membrane, and catholyte flows through the second side of the device where it contacts the other face of the proton conducting membrane. The concentration gradient of protons from high concentration in the catholyte to low concentration in the anolyte is the driving force for proton diffusion, rather than electromotive force, which greatly simplifies the design and operation.

Abstract: A flow battery system with a cathode cell including a first electrode, an anode cell includes a second electrode, and a membrane between the two cells. A first electrolyte tank includes a catholyte. A second electrolyte tank includes an anolyte. The system includes two rebalancing cells. A first rebalancing cell is in fluid communication between the cathode cell and the first electrolyte tank and is configured to reduce active species from the catholyte. The second rebalancing cell is in fluid communication with the first electrolyte tank and the second electrolyte tank such that the first electrolyte tank and the second electrolyte tank are in direct fluid communication. The second rebalancing cell is configured to reduce active species from the catholyte and the reduced catholyte may be combined directly with the anolyte. The second rebalancing cell may be a chemical reactor, a catalytic reactor, or an electrochemical reactor.

Abstract: A method of refreshing an asymmetric redox flow battery system is described. The redox flow battery system comprises: at least one rechargeable cell comprising a positive electrolyte, a negative electrolyte, and a separator positioned between the positive electrolyte and the negative electrolyte, the positive electrolyte in contact with a positive electrode, and the negative electrolyte in contact with a negative electrode; the positive electrolyte comprising water and a metal precursor and having a volume; the negative electrolyte comprising water and the metal precursor and having a volume; the negative electrolyte having a concentration of the metal precursor greater than a concentration of the metal precursor in the positive electrolyte. The flow of mixed electrolyte past the negative electrode is prevented, and the negative electrolyte and positive electrolyte are mixed together.

Abstract: A redox flow battery system having decreased cross-over of active species and decreased hydrogen generation, which is particularly important with less expensive polyethylene or polypropylene membranes. The redox flow battery system comprises at least one rechargeable cell comprising a positive electrolyte, a negative electrolyte, and a separator positioned between the positive electrolyte and the negative electrolyte. The positive electrolyte is in contact with a positive electrode, and the negative electrolyte is in contact with a negative electrode. The positive and negative electrolytes comprise water and a metal precursor, and the concentration of the metal precursor in the negative electrolyte is greater than the concentration of the metal precursor in the positive electrolyte. The metal in the metal precursor comprises iron, copper, zinc manganese, titanium, tin, silver, vanadium, or cerium.

Abstract: A redox flow battery with an electrochemical balancing cell having first and second chambers. The first chamber includes a catalyst coated substrate and the second chamber includes an electrode. Each receives an electrolyte from the redox flow battery. There is a single interface between the two chambers. The balancing cell reverses parasitic reactions in the first chamber that occur in the redox flow battery. The products of the reversed reactions are carried away from the electrochemical balancing cell and back to the redox flow battery in the electrolyte that carried the reactant to the first chamber. Also, processes for reversing a parasitic reaction in a redox flow battery.

Abstract: A redox flow battery system comprising a catholyte in fluid communication with a cathode, an anolyte in fluid communication with an anode, a membrane in fluid communication with the catholyte and the anolyte, and positive and negative terminals in contact with a power supply and a load. The positive and negative terminals configured to charge the redox flow battery in an opposite direction such that the anolyte is oxidized and the catholyte is reduced. The anolyte and the catholyte are kept separate and never mixed.