Abstract: A method is provided for mitigating hydrogen evolution within a flow battery system that includes a plurality of flow battery cells, a power converter and an electrochemical cell. The method includes providing hydrogen generated by the hydrogen evolution within the flow battery system to the electrochemical cell. A first electrical current generated by an electrochemical reaction between the hydrogen and a reactant is sensed, and the sensed current is used to control an exchange of electrical power between the flow battery cells and the power converter.

Abstract: An aircraft fuel tank ullage gas management system is disclosed. The system includes an electrochemical cell having a membrane electrode assembly that includes a cathode and anode separated by an electrolyte separator. A cathode fluid flow path is in fluid communication with the cathode, and receives the flow of cabin air from the cabin air fluid flow path and discharges nitrogen-enriched air. An anode fluid flow path is in fluid communication with the anode, and discharges oxygen or oxygen-enriched air. The electrochemical cell also includes water in fluid communication with the anode. The system includes an electrical power source and electrical connections to the anode and cathode for providing an electric potential difference between the anode and cathode. An ullage flow path receives nitrogen-enriched air from the cathode fluid flow path and delivers it to the fuel tank. An optional flow path delivers humidified oxygen-enriched air back to the cabin.

Abstract: A flow battery includes at least one cell that has 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 reactant material is stored within a storage portion and selectively delivered to the at last one cell. At least one reactant material is present in a solid phase in the storage portion and is present in a liquid phase in the at least one cell.

Abstract: A flow battery includes a cell stack that has electrochemically active cells and manifolds that define common manifold passages in fluid communication with the electrochemically active cells. A supply/storage system is external of the cell stack and includes at least one vessel fluidly connected with respective ones of the common manifold passages. Fluid electrolytes are in the supply/storage system. At least one of the fluid electrolytes is an ionic-conductive fluid. The manifolds extend in a length direction through the cell stack. The common manifold passages include a common manifold passage P that varies in cross-section along the length direction.

Abstract: A flow battery includes a cell that has 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 is external of the at least one cell and includes first and second vessels that are fluidly connected with the at least one cell. First and second fluid electrolytes are located in the supply/storage system. The electrolyte separator layer includes a hydrated ion-exchange membrane of a polymer that has a carbon backbone chain and side chains extending from the carbon backbone chain. The side chains include hydrophilic chemical groups with water molecules attached by secondary bonding to form clusters of water domains. The clusters have an average maximum cluster size no greater than 4 nanometers, with an average number of water molecules per hydrophilic chemical group, ? (lambda), being greater than zero.

Abstract: A method of in-situ electrolyte preparation in a flow battery includes providing a vanadium-based electrolyte solution having vanadium ions of predominantly vanadium V4+ to a first electrode and a second electrode of at least one cell of a flow battery. The vanadium V4+ at the first electrode is converted to vanadium V3+ and the vanadium V4+ at the second electrode is converted to vanadium V5+ by providing electrical energy to the electrodes. A reducing agent is then provided to the vanadium V5+ at the second electrode to reduce the V5+ to vanadium the V4+. The vanadium V3+ at the first electrode is then converted to vanadium V2+ and the vanadium V4+ at the second electrode is then converted to vanadium V5+ by providing electrical energy to the electrodes. A simple method to produce predominantly vanadium V4+ electrolyte from a V5+ source, such as V2O5, is also taught.

Abstract: A method of operating a power generation system includes operating a power generation system to generate an electric power output. At least a portion of the electric power output is dissipated in a flow battery by charging the flow battery using the portion of the electric power output and self-discharging the flow battery.

Abstract: A method of maintaining health of a flow battery includes determining an average oxidation state of a common electrochemically active elemental specie in first and second fluid electrolytes on, respectively, a positive side and a negative side of an electrochemical cell of a flow battery, and adjusting the average oxidation state in response to the average oxidation state deviating from a predefined average oxidation state value.

Abstract: A flow battery includes a cell that has first and second flow fields spaced apart from each other and an electrolyte separator layer. A supply/storage system is external of the cell and includes first and second vessels fluidly connected with the first and second flow fields, and first and second pumps configured to selectively move first and second fluid electrolytes between the vessels and the first and second flow fields. The flow fields each have an electrochemically active zone that is configured to receive flow of the fluid electrolytes. The electrochemically active zone has a total open volume that is a function of at least one of a power parameter of the flow battery, a time parameter of the pumps and a concentration parameter of the fluid electrolytes.

Abstract: A flow battery includes at least a cell that has a first electrode, a second electrode and an electrolyte separator layer arranged between the electrodes. A supply/storage system is external of the cell and includes a first vessel fluidly connected in a first loop with the first electrode and a second vessel fluidly connected in a second loop with the second electrode. The first loop and the second loop are isolated from each other. The supply/storage system is configured to fluidly connect the first loop and the second loop to move a second liquid electrolyte from the second vessel into a first liquid electrolyte in the first vessel responsive to a half-cell potential at the first electrode being less than a defined threshold half-cell potential.

Abstract: A flow battery system includes an ON mode, and OFF mode and a STANDBY mode. The ON mode enables access to a full energy capacity of the flow battery system with regard to an amount of electric power that can be drawn from or stored to the flow battery system. The OFF mode disables access to the full energy capacity and the STANDBY mode enables access to a portion of the full energy capacity.

Abstract: A membrane electrode assembly includes an anode including a hydrogen oxidation catalyst; a cathode; a membrane disposed between the anode and the cathode; and a peroxide decomposition catalyst positioned in at least one position selected from the group consisting of a layer between the anode and the membrane and a layer between the cathode and the membrane wherein the peroxide decomposition catalyst has selectivity when exposed to hydrogen peroxide toward reactions which form benign products from the hydrogen peroxide. The peroxide decomposition catalyst can also be positioned within the membrane. Also disclosed is a power-generating fuel cell system including such a membrane electrode assembly, and a process for operating such a fuel cell system. The assembly components contain ionomer material which can be perfluorinated or non-perfluorinated, high temperature, hydrocarbon, and the like.

Abstract: A technique is disclosed of modified shut-down of a fuel cell power plant (14) having a fuel cell stack assembly (26) contained with and supplying electrical power to a mobile vehicle (12). The vehicle characteristically proceeds at intervals to a station (10) containing one or more resources (20, 20A, 20B, 20C, etc) utilized by the fuel cell power plant, for resupply thereof. One such, resource provided at/by the station is electrical energy (20A), aid operation of the fuel cell power plant (14) is controlled to utilize the availability of that electrical energy (20A) to maintain, an active protective Hydrogen On condition for greatly extended intervals, for example many hours to several days or longer, via a Power On mode of operation. The Power On mode maintains at least a low level of hydrogen introduction and circulation sufficient to maintain a predetermined presence, e.g., pressure, of hydrogen at the fuel cell stack assembly (26).

Abstract: A method of treating a carbon electrode includes providing a carbon-based electrode that has a surface with chemically different carbon oxides. The surface is treated with a reducing agent to reduce at least a portion of the oxides to a target carbon oxide. In an aspect, a method of treating a carbon electrode includes providing a carbon-based electrode that has a surface with an initial non-zero concentration of a target carbon oxide. The surface is then treated with a reducing agent to increase the initial non-zero concentration of the target carbon oxide.

Abstract: A fuel cell includes a membrane electrode assembly having an anode side and a cathode side, a first gas diffusion layer adjacent the cathode side of the membrane electrode assembly, and a first flow field plate contacting the first gas diffusion layer. The first flow field plate includes a reactant inlet, a reactant outlet, and a plurality of flow field chambers separated from one another by at least one rib. The reactant inlet is separated from the plurality of flow field chambers by at least one rib and the reactant outlet is separated from the plurality of flow field chambers by at least one rib. The ribs are configured to force a reactant flowing from the reactant inlet to the reactant outlet to enter the first gas diffusion layer at least twice.

Abstract: A flow battery includes an electrode operable to be wet by a solution having a reversible redox couple reactant. In one embodiment, the electrode can have plurality of micro and macro pores, wherein the macro pores have a size at least one order of magnitude greater than a size of the micro pores. In another embodiment, the electrode includes a plurality of layers, wherein one of the plurality of layers has a plurality of macro pores, and wherein another one of the plurality of layers has a plurality of micro pores. In another embodiment, the electrode has a thickness less than approximately 2 mm. In still another embodiment, the electrode has a porous carbon layer, wherein the layer is formed of a plurality of particles bound together.

Abstract: A flow battery includes at least one cell that has a first electrode, a second electrode spaced apart from the first electrode and an electrolyte separator layer that is arranged between the first electrode and the second electrode. A storage portion is fluidly connected with the at least one cell. At least one liquid electrolyte includes an electrochemically active specie and is selectively deliverable to the at least one cell. An electric circuit is coupled with the first electrode and the second electrode. The circuit includes a voltage-limiting device that is configured to limit a voltage potential across the first electrode and the second electrode in response to a transition of the at least one cell from an inactive, shut-down mode with respect to an active, charge/discharge mode.

Abstract: A flow battery includes a first liquid-porous electrode, a second liquid-porous electrode spaced apart from the first liquid-porous electrode, and an ion-exchange membrane arranged between the first liquid-porous electrode and the second liquid-porous electrode. First and second flow fields are adjacent to the respective first liquid-porous electrode and second liquid-porous electrode. Each of the flow fields includes first channels having at least partially blocked outlets and second channels having at least partially blocked inlets. The second channels are interdigitated with the first channels. The flow fields provide a configuration and method of operation for relatively thin electrodes with moderate pressure drops and forced convective flow through the liquid-porous electrodes.

Abstract: An electrochemical device includes a plurality of electrode assemblies that define a plurality of electrochemically active areas. A non-electrically-conductive manifold includes a common manifold passage and a plurality of branch passages that extend, respectively, between the electrochemically active areas and the common manifold passage. Each of the branch passages includes a first region and a second region that differ in surface area.

Abstract: A flow battery includes a liquid electrolyte that has an electrochemically active specie and a bipolar plate that has channels for receiving flow of the liquid electrolyte. A porous electrode is arranged immediately adjacent the bipolar plate. The porous electrode is catalytically active with regard to the liquid electrolyte. The channels of the bipolar plate have at least one of a channel arrangement or a channel shape that is configured to positively force at least a portion of the flow of the liquid electrolyte into the porous electrode.