Methods and systems are provided for a redox flow battery system. In one example, a method of operating a redox flow battery system includes switching the redox flow battery system to an idle mode and completely draining electrolytes from one or more electrode compartments of the redox flow battery system. The one or more electrode compartments may be purged with a gas and refilled with fresh electrolytes.

Disclosed herein is a redox flow battery (RFB). The battery generally includes: a positive electrolyte that is a first metal ion, a negative electrolyte that is a second metal ion, an ion exchange membrane positioned between the positive electrolyte and the negative electrolyte. The membrane is configured to restrict and/or prevent the passage of the first metal ion and/or the second metal ion therethrough, and is configured to maintain ionic conductivity between the positive electrolyte and the negative electrolyte.

In a redox flow battery (RFB), the base solvent of the electrolytes tends to migrate across the barrier layer from one electrode toward the other. This can result in a volume and concentration imbalance between the electrolytes that is detrimental to battery efficiency and capacity. Compatible electrolytes can be mixed to rebalance the system, but for incompatible electrolytes mixing is not a viable option. To this end, the RFB herein includes a separator that recovers base solvent from the vapor phase of one of the electrolytes and returns the recovered base solvent to the other electrolyte to thereby reverse the imbalance.

Methods and systems are provided for a redox flow battery system. In one example, a method of operating a redox flow battery system includes, responsive to switching the redox flow battery system to an idle mode, initiating a first timer monitoring a first threshold period of time. An electrolyte pump may be activated when the first threshold period of time elapses, the electrolyte pump driving circulation of electrolytes through one or more electrode compartments.

A redox flow battery includes first and second cells. Each cell has electrodes and a separator layer arranged between the electrodes. A first circulation loop is fluidly connected with the first electrode of the first cell. A polysulfide electrolyte solution has a pH 11.5 or greater and is contained in the first recirculation loop. A second circulation loop is fluidly connected with the second electrode of the second cell. An iron electrolyte solution has a pH 3 or less and is contained in the second circulation loop. A third circulation loop is fluidly connected with the second electrode of the first cell and the first electrode of the second cell. An intermediator electrolyte solution is contained in the third circulation loop. The cells are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.

A redox flow battery which includes a battery cell to which a positive-electrode electrolyte and a negative-electrode electrolyte are supplied; a plurality of positive-electrode electrolyte tanks that store the positive-electrode electrolyte; a plurality of negative-electrode electrolyte tanks that store the negative-electrode electrolyte; a positive-electrode electrolyte tank switching device that switches a positive-electrode electrolyte tank among the plurality of positive electrolyte tanks; a negative-electrode electrolyte tank switching device that switches a negative-electrode electrolyte tank among the plurality of negative-electrode electrolyte tanks; a polarity switching unit that switches the polarity of the electrodes of the battery cells; and a controller for controlling switching the polarity of the electrodes, switching of the plurality of positive-electrode electrolyte tanks and switching of the plurality of negative-electrode electrolyte tanks. Also disclosed is a method for operating the redox flow battery.

A method is provided for restoring an electrolyte of vanadium (V) redox flow battery (VRFB). Electrolyte data of an original system are analyzed in advance. A reusable positive electrode is further equipped with a V electrolyte. A reductant for a stack of VRFB is used in coordination as an electrolysis device. After a long-term reaction with a VRFB having a high valence (greater than 3.5), an electrolyte at the positive electrode is directed out to a negative electrode of the electrolysis device; and, then, electrolysis is processed after accurate calculation. In the end, the internal fluid balancing method of the original system is combined. Thus, a harmless and quick valence restoration is processed for the electrolyte of the original system, which is a final resort for the restoration of V electrolyte.

A redox flow battery includes first and second cells. Each cell has electrodes and a separator layer arranged between the electrodes. A first circulation loop is fluidly connected with the first electrode of the first cell. A polysulfide electrolyte solution has a pH 11.5 or greater and is contained in the first recirculation loop. A second circulation loop is fluidly connected with the second electrode of the second cell. An iron electrolyte solution has a pH 3 or less and is contained in the second circulation loop. A third circulation loop is fluidly connected with the second electrode of the first cell and the first electrode of the second cell. An intermediator electrolyte solution is contained in the third circulation loop. The cells are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.

The present invention relates to an electrolyte storage unit applicable to redox flow batteries and a vanadium redox flow battery including the same. The electrolyte storage unit for redox flow batteries of the present invention can be useful in minimizing a contact area of an electrolyte with the air to improve a self-discharge phenomenon of a battery and solving a problem such as an imbalance between a concentration and a volume of the electrolyte, which is caused during battery driving. Accordingly, a cycle of a process of regenerating an electrolyte can be delayed, and capacity and lifespan characteristics of the battery can be improved. Also, the electrolyte storage unit of the present invention can be easily handled and installed because electrolytes may not be easily mixed even by external impact.

A method for controlling driving of a chemical flow battery is disclosed. The method includes: measuring a concentration of bromine (Br2) in an electrolyte solution of a chemical flow battery after a complete discharge; and additionally supplying bromine (Br2) into the electrolyte solution until the concentration of bromine (Br2) satisfies a predefined condition.