The present invention is directed to a redox flow battery comprising at least one electrochemical cell in fluid communication with a balancing cell, said balancing cell comprising: a first and second half-cell chamber, wherein the first half-cell chamber comprises a first electrode in contact with a first aqueous electrolyte of the redox flow battery; and wherein the second half-cell chamber comprises a second electrode in contact with a second aqueous electrolyte, said second electrode comprising a catalyst for the generation of O.sub.2.

A system and method of controlling a performance of a fuel cell stack is provided. In particular, the output performance of the fuel cell stack is determined by comparing the difference between an initial voltage and a voltage after a predetermined time lapses with the difference between the initial voltage and a preset minimum voltage.

The present invention comprises a method and system for improving the energy efficiency of a vanadium flow battery, VFB. This is achieved by simultaneously reconditioning the VFB through in-situ activation of the electrodes.

A PEM fuel system includes a fuel cell stack comprising one or more PEM fuel cells and fan configured to provide process air to supply oxidizer to and cool the fuel cell stack. The system has an air duct coupled to the fan and the fuel cell stack, and an electrical service load coupled to the fuel cell stack for receiving electrical power generated from reactions within the fuel cell stack. The system further includes as auxiliary electrical load coupled to the fuel cell stack and located within the air duct to reduce potentials across the fuel cell stack. The air duct is configured to direct the flow of air to the fuel cell stack and auxiliary electrical load to provide cooling air to the fuel cell stack and auxiliary electrical load.

A method for recovering performance of a fuel cell stack includes 1) a first pulse operation process including i) generating a hydrogen pumping reaction in a cathode by applying a current to the cathode after a supply of air to the cathode stops and ii) maintaining an OCV (open circuit voltage) by again supplying air to the cathode after the hydrogen pumping is performed, 2) a pole substitution process of substituting a pole of the fuel cell stack, and 3) a second pulse operation process including iii) generating the hydrogen pumping reaction in the cathode after the pole substitution, and iv) maintaining the CCV (open circuit voltage) by supplying air to the cathode after the pole substitution after the hydrogen pumping is performed.

An electrochemical reactor, such as a fuel cell stack or an electrolyzer, includes a stack of electrochemical cells, a manifold, a sensor, and a monitor. Each electrochemical cell includes an electrode plate having a face in electrical contact with an electrolyte. The manifold is connected to the faces of the electrochemical cells in an exchange circuit, for exchanging a gas with outside of the stack. The sensor is sensitive to a composition of the gas in the circuit. The monitor monitors or controls an operational condition of the electrochemical reactor in response to measurements by the sensor. The stack and the manifold form a one-piece reactor body. A chamber is integrated into the body in communication with the manifold. The sensor is mounted in the body and includes a sensitive or sensing unit exposed directly to an in situ concentration of a component of the gas in the chamber.

A method for recovering the performance of a fuel cell stack mounted within a vehicle is provided. A method includes a recovery process of continuously applying a predetermined load using a load device when an air supply is stopped and hydrogen is supplied to a fuel cell stack to output current from the fuel cell stack. Further, protons and electrons generated by hydrogen oxidation reaction at an anode are moved to a cathode, to produce hydrogen at the cathode and simultaneously remove oxide on the catalyst surface of the cathode.

A method of operating a fuel cell assembly comprising a plurality of fuel cells connected together for collectively providing power to a load, each fuel cell including an anode and a cathode, the method comprising selectively providing an electrical connection between the anode and the cathode of at least one of the fuel cells of the assembly for lowering the voltage across the fuel cell independent of the load.

The present invention provides a fuel cell system and a startup and shutdown method therefor for avoiding carbon corrosion. The fuel cell system includes at least one fuel cell reaction module with at least one anode chamber to contain an anode reaction fluid. The method includes steps of: (a) executing a shutdown mode, (b) conducting and connecting a first load to the fuel cell reaction module so as to consume the anode reaction fluid remained in the anode chamber, (c) providing a buffer fluid to the anode chamber and disconnecting the first load from the anode chamber; (d) maintaining the fuel cell system shutdown, (e) executing a startup mode, (f) providing the anode reaction fluid to the anode chamber, and (g) conducting and connecting a second load to the fuel cell reaction module and maintaining the fuel cell system operated continuously.

The fuel cell system includes: a fuel cell 40 that receives supply of reactant gas to generate power; output characteristic updating means for updating an output characteristic of the fuel cell 40 based on output current and output voltage measured by a current sensor 140 and a voltage sensor 150; maximum power calculation means for calculating, using the output characteristic, the maximum power available at the fuel cell 40; and determination means for determining whether a value of the output characteristic is in an assumed situation where the output characteristic value is assumed to be temporarily lowered, wherein while the output characteristic value is determined by the determination means to be in the assumed situation, the maximum power calculation means calculates the maximum power using the output characteristic updated by the output characteristic updating means just before transition to the assumed situation.