A redox flow battery includes a cell that has first and second electrodes and an ion-exchange layer there between, first and second circulation loops that are fluidly connected with, respectively, the first and second electrodes, first and second electrolyte storage tanks in, respectively, the first and second circulation loops, first and second electrolytes contained in, respectively, the first and second circulation loops, and a Raman spectrometer on at least one of the first or second circulation loops for determining a state-of-charge of at least one of the first or second electrolytes. The Raman spectrometer includes a laser source that is rated to emit a laser of a wavelength of 694 nanometers to 1444 nanometers.

A redox flow battery includes a tank configured to store an electrolyte and a distribution mechanism to distribute the electrolyte to a battery cell. The tank has a partition portion partitioning a space inside the tank into a first space and a second space, the distribution mechanism has a distribution passage through which the electrolyte is distributed between the first space and the second space via the battery cell, and the partition portion is composed of a flexible material.

A fuel cell system includes a cathode system device, an anode system device, an ion detector, and a controller. When the concentration of fluoride ions exceeds a predetermined concentration threshold, the controller controls at least one of the cathode system device and the anode system device to adjust a load applied to the membrane electrode assemblies.

The balancing of the state of charge of a plurality of flow battery electrolytes is better achieved by a method for a battery having a plurality of flow battery stacks in series and supplied with electrolytes from at least two stores, in which the stacks each having a plurality of cells, the method including measuring and comparing the state of charge of the electrolytes of the respective stores and registering if the states of charge differ by more than a threshold and in the case of the state of the charge difference threshold being exceeded: controlling the number of cells in the series connection of the stacks whereby the less charged electrolytes discharge through fewer cells than the more charged electrolytes and/or controlling the number of cells in the series connection of the stacks whereby the less charged electrolytes are charged through more cells than the more charged electrolytes.

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.

Methods and systems are provided for a rebalancing reactor of a flow battery system. In one example, a pH of a battery electrolyte may be maintained by the rebalancing reactor by applying a negative potential to a catalyst bed of the rebalancing reactor. A performance of the rebalancing reactor may further be maintained by treating the catalyst bed with deionized water.

Designs of redox flow battery arrays and methods for balancing state of charge within the arrays are disclosed. Flow battery unit strings in the arrays which comprise strings of flow battery units (in which units share a common electrolyte pair) are balanced by measuring the states of charge of the common electrolyte pairs and appropriately regulating flow in one or more of the associated anolyte and catholyte circuits so as to balance the state-of charge in the flow battery unit strings. The apparatus required, i.e. state-of-charge measuring device, flow regulator, and controller, represents a substantial simplification to state of the art approaches.

A redox flow battery includes a redox flow cell, a supply/storage system external of the redox flow cell, and a controller. The supply/storage system includes first and second electrolytes for circulation through the redox flow cell. The first electrolyte is a liquid electrolyte having electrochemically active species with multiple, reversible oxidation states. The electrochemically active species can form a solid precipitate blockage in the redox flow cell. The controller is configured to identify whether there is the solid precipitate blockage in the redox flow cell and, if so, initiate a regeneration mode that reduces the oxidation state of the electrochemically active species in the liquid electrolyte to dissolve, in situ, the solid precipitate blockage.

Embodiments of the invention relate to an open metal-air fuel cell system capable of uninterrupted supply power, which relates to the field of metal-air fuel cell stacks and comprises a sensing subsystem, a controller, a circulating filtration subsystem, an electrolyte solution tank and several open metal-air fuel cell units. Open metal-air fuel cell units are sequentially arranged within the electrolyte solution tank, and each open metal-air fuel cell unit is connected with each other in parallel. An air electrode of the open metal-air fuel cell unit has a tank structure, and the trough structure has a concave surface upwards. The sensing subsystem is arranged within the electrolyte tank. The electrolyte solution tank is connected with a circulating filtration subsystem. The controller is used for controlling a circulating flow of the circulating filtration subsystem depending on electrolyte solution temperature information collected by the sensing subsystem.

A fuel cell system includes a fuel cell stack having a plurality of fuel cells that each contain a plurality of fuel electrodes and air electrodes. The system includes a fuel receiving unit connected to the fuel cell stack, which receives a hydrocarbon fuel from a fuel supply. The system includes a fuel exhaust processing unit fluidly coupled to the fuel cell stack by a slip stream, where the fuel exhaust processing unit processes fuel exhaust from the fuel cell stack, and the slip stream is fluidly connected to an exhaust stream flowing from the fuel cell stack. The fuel processing unit removes a first portion of carbon dioxide (CO.sub.2) from fuel exhaust within the slip stream, outputs the first portion of CO.sub.2 in a first stream, and outputs a second portion of CO.sub.2 remaining from the fuel exhaust in the slip stream into a second stream, which includes hydrogen.