In accordance with the principles of the present invention, a system and method for the management of the power applied to electrolytic cell is provided. The power management consists a constant current regulation, H-bridge control by pulse width modulation (PWM), and dimming control of the applied current to the electrolytic cell. The constant current regulation is an analog control that maintains the applied current at a user-defined current setpoint. The time scale of constant current regulation ranges from tenth of microseconds to milliseconds. The PWM control of the H-bridge allows for the instant adjustment of the electrolytic production output by turning the cell on and off; the time scale of the PWM control ranges from tenths of milliseconds to seconds. The dimming control allows the change of the applied constant current; the time scale of the dimming control ranges from milliseconds to hours and longer.

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.

A method for determining a storage capacity or average oxidation state (AOS) of a redox flow battery system including an anolyte and a catholyte includes discharging a portion of the anolyte and catholyte of the redox flow battery system at a discharge rate that is within 10% of a preselected discharge rate; after discharging the redox flow battery system, determining an end OCV; and determining the storage capacity or AOS from the end OCV. Other methods can be used to determine the storage capacity or AOS using a measured OCV.

A redox flow battery system includes an anolyte having chromium ions in solution; a catholyte having iron ions in solution, where a molar ratio of chromium in the anolyte to iron in the catholyte is at least 1.25; a first electrode in contact with the anolyte; a second electrode in contact with the catholyte; and a separator separating the anolyte from the catholyte.

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.

A system includes a redox flow battery system that includes an anolyte, a catholyte, a first half-cell having a first electrode in contact with the anolyte, a second half-cell having a second electrode in contact with the catholyte, and a first separator separating the first half-cell from the second half-cell. The system also includes a balance arrangement that includes a balance electrolyte having vanadium ions in solution, a third half-cell having a third electrode in contact with the anolyte or the catholyte, a fourth half-cell having a fourth electrode in contact with the balance electrolyte, and a reductant in the balance electrolyte or introducible to the balance electrolyte for reducing dioxovanadium ions.

A method of evaluating a movement tendency of ions in an electrolyte membrane includes counting inter-movement ions, counting intra-movement ions and calculating the ratio of the intra-movement ions and inter-movement of ions. The movement tendency of ions is predicted based on the ratio. In the case of evaluating a movement tendency of ions using the method, since the structure of the electrolyte membrane in which the ratios of intra-movement and inter-movement are maximized is predicted through measurement of the ratios of the intra-movement and inter-movement of ions, ohmic resistance that may occur in a membrane-electrode assembly (MEA) may be reduced. The electrolyte membrane having the optimal structure predicted by the method can be applied to a fuel cell to increase its performance.

A system includes a redox flow battery system that includes an anolyte, a catholyte, a first half-cell having a first electrode in contact with the anolyte, a second half-cell having a second electrode in contact with the catholyte, and a first separator separating the first half-cell from the second half-cell. The system also includes a balance arrangement that includes a balance electrolyte having vanadium ions in solution, a third half-cell having a third electrode in contact with the anolyte or the catholyte, a fourth half-cell having a fourth electrode in contact with the balance electrolyte, and a reductant in the balance electrolyte or introducible to the balance electrolyte for reducing dioxovanadium ions.

A redox flow battery system includes a redox flow battery that has a redox flow cell and a supply/storage system. The supply/storage system has first and second electrolytes for circulation through the redox flow cell. At least the first electrolyte is a liquid electrolyte that has electrochemically active species with multiple, reversible oxidation states. A secondary cell is operable to monitor concentration of one or more of the electrochemically active species. The secondary cell has a counter electrode, a flow passage that connects the counter electrode with the redox flow battery to receive the first or second electrolyte, a working electrode, and a separator. The working electrode is isolated from receiving the electrochemically active species of the first and second electrolytes except for a transport passage connecting the flow passage and the working electrode. The transport passage limits movement of the electrochemically active species to the working electrode.

A system includes a redox flow battery system that includes an anolyte having chromium ions in solution, a catholyte having iron ions in solution, a first half-cell having a first electrode in contact with the anolyte, a second half-cell having a second electrode in contact with the catholyte, and a first separator separating the first half-cell from the second half-cell. The system also includes a balance arrangement that includes a balance electrolyte having vanadium ions in solution, a third half-cell having a third electrode in contact with the anolyte or the catholyte, a fourth half-cell having a fourth electrode in contact with the balance electrolyte, and a reductant in the balance electrolyte or introducible to the balance electrolyte for reducing dioxovanadium ions.