An online impedance spectrum measuring device and method for a vehicle-mounted hydrogen fuel cell includes: a controllable alternating current source, configured to apply a sinusoidal alternating signal; a cell voltage signal preceding-stage measuring circuit, configured to select to communicate with one monocell via a voltage signal gating circuit; a current sensor and a cell current signal preceding-stage measuring circuit connected with the current sensor; and a signal conditioning and amplifying circuit, a multi-channel simultaneous sampling analog-digital conversion circuit, a digital signal processor and an upper computer, which are connected in sequence, wherein the signal conditioning and amplifying circuit is connected to the cell voltage signal preceding-stage measuring circuit and the cell current signal preceding-stage measuring circuit, separately; and the upper computer is connected with the controllable alternating source and the voltage signal gating circuit.

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.

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.

According to one embodiment of the present invention, the method for controlling the pump speed of a redox flow battery for transferring an electrolyte stored in an electrolyte tank to a cell stack comprises the steps of: measuring the input power and/or the output power of the redox flow battery; measuring the charging power and/or the discharging power of the redox flow battery; calculating the power loss of the redox flow battery by using the difference between the input power and the charging power, or the difference between the output power and the discharging power; and adjusting the pump speed according to the power loss.

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.

One embodiment provides a method for predicting maintenance of a redox flow battery, the method including: receiving, from a plurality of sensors, data regarding characteristics of the redox flow battery; weighting, using a processor, each of the characteristics to form an estimated state parameter for the redox flow battery; and determining, using the processor, a maintenance action for the redox flow battery using the estimated state parameter. Other aspects are described and claimed.

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 with an electrochemical balancing cell having first and second chambers. The first chamber includes a catalyst coated substrate and the second chamber includes an electrode. Each receives an electrolyte from the redox flow battery. There is a single interface between the two chambers. The balancing cell reverses parasitic reactions in the first chamber that occur in the redox flow battery. The products of the reversed reactions are carried away from the electrochemical balancing cell and back to the redox flow battery in the electrolyte that carried the reactant to the first chamber. Also, processes for reversing a parasitic reaction in a redox flow battery.

An online impedance spectrum measuring device and method for a vehicle-mounted hydrogen fuel cell includes: a controllable alternating current source, configured to apply a sinusoidal alternating signal; a cell voltage signal preceding-stage measuring circuit, configured to select to communicate with one monocell via a voltage signal gating circuit; a current sensor and a cell current signal preceding-stage measuring circuit connected with the current sensor; and a signal conditioning and amplifying circuit, a multi-channel simultaneous sampling analog-digital conversion circuit, a digital signal processor and an upper computer, which are connected in sequence, wherein the signal conditioning and amplifying circuit is connected to the cell voltage signal preceding-stage measuring circuit and the cell current signal preceding-stage measuring circuit, separately; and the upper computer is connected with the controllable alternating source and the voltage signal gating circuit.

Methods and systems are provided for a redox flow battery system. In one example, the redox flow battery system includes a power module, an electrolyte pump, and a power control system. The power control system may include instructions to switch the redox flow battery system to an idle mode, activate an electrolyte pump when a first threshold period of time elapses, deactivate the electrolyte pump when a second threshold period of time elapses, and drain, purge, and refill one or more electrode compartments when a third threshold period of time elapses.