Abstract: A method of making an Fe—Cr electrolyte includes a) oxidizing a carbon-containing Fe—Cr alloy with Fe2O3 or FeO; and b) treating the oxidized carbon-containing Fe—Cr alloy with FeCl3 or HCl or any combination thereof to produce a FeCl2—CrCl3 electrolyte. The method may also include treating, under reducing conditions, a starting material, such as chromite ore, with a carbon source to produce the carbon-containing Fe—Cr alloy. Additionally or alternatively, the method may include removing a portion of the FeCl2 from the FeCl2—CrCl3 electrolyte to obtain a selected iron to chromium molar ratio for the Fe—Cr electrolyte.

Abstract: A U-tube arrangement for monitoring, observing, or measuring gas flow or gas generation of in a closed system can include a U-tube having a first arm, a second arm, and a bridge connecting the first arm to the second arm; a liquid disposed in the U-tube; an attachment conduit for coupling to the closed system and in fluid communication with the first arm of the U-tube and the closed system; a first valve for controlling fluid flow between the first arm of the U-tube and the closed system; an external conduit in fluid communication with the second arm of the U-tube and either an external atmosphere or external pressure source; and liquid level sensors disposed along at least one of the first arm or the second arm.

Abstract: A method for determining an average oxidation state (AOS) of a redox flow battery system includes measuring a charge capacity for a low potential charging period starting from a discharged state of the redox flow battery system to a turning point of a charge voltage; and determining the AOS using the measured charge capacity and volumes of anolyte and catholyte of the redox flow battery system. Other methods can be used to determine the AOS for a redox flow battery system or use discharge voltage instead of charging voltage.

Abstract: In one embodiment of the present disclosure, a composition for producing a vanadium electrolyte includes a vanadium compound and an ion solution containing vanadium ions and hydrogen ions. In another embodiment, a method for producing a vanadium electrolyte includes obtaining a vanadium compound, and mixing the vanadium compound with an ion solution containing vanadium ions and hydrogen ions.

Abstract: In one embodiment of the present disclosure, a composition for producing a vanadium electrolyte includes a vanadium compound and an ion solution containing vanadium ions and hydrogen ions. In another embodiment, a method for producing a vanadium electrolyte includes obtaining a vanadium compound, and mixing the vanadium compound with an ion solution containing vanadium ions and hydrogen ions.

Abstract: In one embodiment of the present disclosure, a composition for producing a vanadium electrolyte includes a vanadium compound and an ion solution containing vanadium ions and hydrogen ions. In another embodiment, a method for producing a vanadium electrolyte includes obtaining a vanadium compound, and mixing the vanadium compound with an ion solution containing vanadium ions and hydrogen ions.

Abstract: A method for preparation of electrolyte for a redox flow battery includes reducing chromium ore using a carbon source to convert the chromium ore to an iron/chromium alloy with carbon particles; dissolving the iron/chromium alloy with carbon particles in sulfuric acid to form a first solution; adding calcium chloride or barium chloride to the first solution to produce a second solution including FeCl3 and CrCl3; and adding an acid to the second solution to form the electrolyte. Other methods can be used for preparing an electrolyte from chromium waste material.

Abstract: A method for preparation of electrolyte for a redox flow battery includes reducing chromium ore using a carbon source to convert the chromium ore to an iron/chromium alloy with carbon particles; dissolving the iron/chromium alloy with carbon particles in sulfuric acid to form a first solution; adding calcium chloride or barium chloride to the first solution to produce a second solution including FeCl3 and CrCl3; and adding an acid to the second solution to form the electrolyte. Other methods can be used for preparing an electrolyte from chromium waste material.

Abstract: In one embodiment of the present disclosure, a composition for producing a vanadium electrolyte includes a vanadium compound and an ion solution containing vanadium ions and hydrogen ions. In another embodiment, a method for producing a vanadium electrolyte includes obtaining a vanadium compound, and mixing the vanadium compound with an ion solution containing vanadium ions and hydrogen ions.

Abstract: One embodiment is a redox flow battery system that includes an anolyte; a catholyte; an anolyte tank configured for holding at least a portion of the anolyte; a catholyte tank configured for holding at least a portion of the catholyte; a primary redox flow battery arrangement, and a second redox flow battery arrangement. The primary and secondary redox flow battery arrangements share the anolyte and catholyte tanks and each includes a first half-cell including a first electrode in contact with the anolyte, a second half-cell including a second electrode in contact with the catholyte, a separator separating the first half-cell from the second half-cell, an anolyte pump, and a catholyte pump. The peak power delivery capacity of the secondary redox flow battery arrangement is less than the peak power delivery capacity of the primary redox flow battery arrangement.

Abstract: One embodiment is a redox flow battery system that includes an anolyte; a catholyte; an anolyte tank configured for holding at least a portion of the anolyte; a catholyte tank configured for holding at least a portion of the catholyte; a primary redox flow battery arrangement, and a second redox flow battery arrangement. The primary and secondary redox flow battery arrangements share the anolyte and catholyte tanks and each includes a first half-cell including a first electrode in contact with the anolyte, a second half-cell including a second electrode in contact with the catholyte, a separator separating the first half-cell from the second half-cell, an anolyte pump, and a catholyte pump. The peak power delivery capacity of the secondary redox flow battery arrangement is less than the peak power delivery capacity of the primary redox flow battery arrangement.

Abstract: A redox flow battery system includes an anolyte; a catholyte; a first electrode structure including a first electrode, a second electrode, and a base disposed between the first and second electrodes, the base including a thermoplastic material and conductive elements disposed in the thermoplastic material, wherein at least one of the first electrode or the second electrode is thermally bonded to the base by heating the base to soften the thermoplastic material and pressing the at least one of the first electrode or the second electrode into the thermoplastic material of the base; a first half-cell in which the first electrode is in contact with the anolyte; and a second half-cell in which the second electrode is in contact with the catholyte.

Abstract: A method for making an aqueous hypochlorous acid (HClO) solution includes electrolyzing a solution of sodium chloride to produce a solution of sodium hypochlorite; and producing the aqueous hypochlorous acid solution by adjusting a pH of the solution of sodium hypochlorite to a value within a range of 3 to 8 by adding a selected weak acid to the solution of sodium hypochlorite to produce a buffer including the selected weak acid and a salt of the selected weak acid.

Abstract: A redox flow battery system includes an anolyte; a catholyte; a first half-cell including a first electrode in contact with the anolyte; a second half-cell including a second electrode in contact with the catholyte; a separator separating the anolyte in the first half-cell from the catholyte in the second half-cell; at least one state measurement device configured for intermittently, periodically, or continuously making a measurement of a value indicative of a state of charge of the anolyte or the catholyte before entering or after leaving the first half-cell or second half-cell, respectively; and a controller coupled to the at least one state measurement device for generating a temporal energy profile of the anolyte or the catholyte, respectively, using the measurements.

Abstract: A redox flow battery system includes an anolyte having chromium ions in solution, wherein at least a portion of the chromium ions form a chromium complex with at least one of the following: NH3, NH4+, CO(NH2)2, SCN?, or CS(NH2)2; a catholyte having iron ions in solution; a first half-cell including a first electrode in contact with the anolyte; a second half-cell including a second electrode in contact with the catholyte; and a first separator separating the first half-cell from the second half-cell.

Abstract: A method for determining an average oxidation state (AOS) of a redox flow battery system includes measuring a charge capacity for a low potential charging period starting from a discharged state of the redox flow battery system to a turning point of a charge voltage; and determining the AOS using the measured charge capacity and volumes of anolyte and catholyte of the redox flow battery system. Other methods can be used to determine the AOS for a redox flow battery system or use discharge voltage instead of charging voltage.

Abstract: One embodiment is a redox flow battery system that includes an anolyte; a catholyte; an anolyte tank configured for holding at least a portion of the anolyte; a catholyte tank configured for holding at least a portion of the catholyte; a primary redox flow battery arrangement, and a second redox flow battery arrangement. The primary and secondary redox flow battery arrangements share the anolyte and catholyte tanks and each includes a first half-cell including a first electrode in contact with the anolyte, a second half-cell including a second electrode in contact with the catholyte, a separator separating the first half-cell from the second half-cell, an anolyte pump, and a catholyte pump. The peak power delivery capacity of the secondary redox flow battery arrangement is less than the peak power delivery capacity of the primary redox flow battery arrangement.

Abstract: A redox flow battery system includes an anolyte having a first ionic species in solution; a catholyte having a second ionic species in solution, where the redox flow battery system is configured to reduce the first ionic species in the anolyte and oxidize the second ionic species in the catholyte during charging; a first electrode in contact with the anolyte, where the first electrode includes channels for collection of particles of reduced metallic impurities in the anolyte; a second electrode in contact with the catholyte; and a separator separating the anolyte from the catholyte. A method of reducing metallic impurities in an anolyte of a redox flow battery system includes reducing the metallic impurities in the anolyte; collecting particles of the reduced metallic impurities; and removing the collected particles using a cleaning solution.

Abstract: A method for determining an average oxidation state (AOS) of a redox flow battery system includes measuring a charge capacity for a low potential charging period starting from a discharged state of the redox flow battery system to a turning point of a charge voltage; and determining the AOS using the measured charge capacity and volumes of anolyte and catholyte of the redox flow battery system. Other methods can be used to determine the AOS for a redox flow battery system or use discharge voltage instead of charging voltage.

Abstract: A redox flow battery system includes an anolyte having chromium ions in solution, wherein at least a portion of the chromium ions form a chromium complex with at least one of the following: NH3, NH4+, CO(NH2)2, SCN?, or CS(NH2)2; a catholyte having iron ions in solution; a first half-cell including a first electrode in contact with the anolyte; a second half-cell including a second electrode in contact with the catholyte; and a first separator separating the first half-cell from the second half-cell.