A fuel cell system for air vehicles, wherein the fuel cell system comprises: a fuel cell, a fuel gas system for supplying fuel gas to the fuel cell, a potential sensor, and a controller; wherein the fuel gas system comprises a fuel gas supplier; wherein the controller determines whether or not a potential of the fuel cell measured by the potential sensor, is a reversal potential; and wherein, when the controller determines that the potential of the fuel cell is a reversal potential, the controller increases a fuel gas supply from the fuel gas supplier to the fuel cell.

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 method of determining a distribution of electrolytes in a flow battery includes providing a flow battery with a fixed amount of fluid electrolyte having a common electrochemically active specie, a portion of the fluid electrolyte serving as an anolyte and a remainder of the fluid electrolyte serving as a catholyte. An average oxidation state of the common electrochemically active specie is determined in the anolyte and the catholyte and, responsive to the determined average oxidation state, a molar ratio of the common electrochemically active specie between the anolyte and the catholyte is adjusted to increase an energy discharge capacity of the flow battery for the determined average oxidation state.

A method of determining a distribution of electrolytes in a flow battery includes providing a flow battery with a fixed amount of fluid electrolyte having a common electrochemically active specie, a portion of the fluid electrolyte serving as an anolyte and a remainder of the fluid electrolyte serving as a catholyte. An average oxidation state of the common electrochemically active specie is determined in the anolyte and the catholyte and, responsive to the determined average oxidation state, a molar ratio of the common electrochemically active specie between the anolyte and the catholyte is adjusted to increase an energy discharge capacity of the flow battery for the determined average oxidation state.

A fuel cell system having a fuel cell control module (FCU) and a method of controlling the same are provided. The method includes selecting one of at least one control parameter and learning system efficiency at each of at least one configurable candidate value of the selected control parameter based on supplied current by driving the fuel cell system. Additionally, the method includes determining a value of the selected control parameter by comparing the system efficiency at each of the at least one configurable candidate value of the selected control parameter with system efficiency corresponding to an initial performance index, at each of at least one predetermined representative current point. Thereby, efficiency of the fuel cell system is improved.

Methods of determining concentrations and/or amounts of redox-active elements at each valence state in an electrolyte solution of a redox flow battery are provided. Once determined, the concentrations and/or amounts of the redox-active elements at each valence state can be used to determine side-reactions, make chemical adjustments, periodically monitor battery capacity, adjust performance, or to otherwise determine a baseline concentration of the redox-active ions for any purpose.

A method for starting a fuel cell in a fuel cell system, at temperatures below the freezing point of water, includes, in a first step, that the hydrogen concentration in the anode is increased; after which, in a second step, an anode pressure is increased for a fixed period of time, and while air is supplied to the cathode, the maximum possible current is drawn from the fuel cell, and after which, in a third step, the fuel cell is switched in a load-free manner and the anode pressure is reduced. After the third step, the second step and the third step are repeated successively until a sufficient performance of the fuel cell for its normal operation is reached.

The present disclosure relates to an apparatus for controlling an operation of a fuel cell system and a method therefor. The present disclosure may include a voltage sensor that measures an output voltage of a fuel cell stack, an air compressor that supplies air to a cathode of the fuel cell stack, a valve driver that adjusts an opening degree of an Airflow Control Valve (ACV), and a controller that, in an idle stop state, drives the air compressor at a lowest level and controls the opening degree of the ACV such that the output voltage of the fuel cell stack maintains a reference range.

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.

Provided is an apparatus for soft-sensing a fuel cell system. The apparatus includes: a connecting unit detachable from a control unit for being connected to an outside of a stationary fuel cell system; a collecting unit connected to the connecting unit and receiving data of the stationary fuel cell system; a quality variable predicting unit connected to the collecting unit and predicting a quality variable of the stationary fuel cell system based on the received data; and a monitoring unit connected to the quality variable predicting unit and outputting the predicted quality variable. The quality variable predicting unit is configured to predict the quality variable predictable including at least any one of a concentration of carbon monoxide in a reformed gas at a rear end of a fuel converting system, and a concentration of methane in the reformed gas at the rear end of the fuel converting system.