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 comprising a catalyst for the generation of O.sub.2; and wherein the second half-cell chamber does not contain an aqueous electrolyte.

A fuel cell system and a method of operating the same is provided that is capable of reducing degradation of a cathode catalyst of a fuel cell. A fuel cell system is provided that includes a fuel cell having a catalyst used for an anode, wherein a carrier of the catalyst is composed of a material with a property where electric resistance in an oxygen containing atmosphere is greater than electric resistance in a hydrogen atmosphere; and a control device configured to control the fuel cell, when supply of fuel gas is stopped during stoppage of operation of the fuel cell, to consume all or part of the fuel gas in a fuel gas chamber, followed by introducing oxygen containing gas into the fuel gas chamber.

A fuel cell containment system wherein fan exhaust is ducted in a manner that directs the flow of air into or from hydrogen storage system or other fuel cell component housing, creating an active ventilation of the storage system. During standby operations, cooling air supporting the control electronics may be ducted into the hydrogen storage system likewise creating an active ventilation of the hydrogen storage system.

The invention relates to a method for operating a fuel cell system comprising a fuel cell stack having an anode and a cathode, in which the following steps for oxidizing impurities present in the anode, in particular adsorbates, are performed: S1 Interrupt the supply of air to the cathode of the fuel cell stack and ramp down the cell voltage by electrochemically reducing residual oxygen present in the cathode, S2 Interrupt the supply of hydrogen to the anode and electrochemically pump residual hydrogen present in the anode to the cathode, and S3 Oxidize the impurities by increasing the anode potential.

The invention also relates to a control device for carrying out steps of the method according to the invention.

The invention relates to a method for operating a PEM fuel cell system having at least one fuel cell stack for regenerating a cathode catalyst of the fuel cell system as required, the method comprising the steps of: supplying the fuel cell system with hydrogen and oxygen in order to carry out a fuel cell process in a normal operating phase; continuously and/or repeatedly acquiring at least one operating parameter for evaluating performance of the fuel cell system; and initiating a temporary regeneration phase of the at least one fuel cell stack, consisting of: providing external electrical power for compensating for the electrical power of the relevant fuel cell stack; interrupting the supply to the relevant fuel cell stack of oxygen; introducing purge gas into a cathode portion of the relevant fuel cell stack; and, after a predetermined flushing time has elapsed, canceling the temporary regeneration phase in order to carry on the normal operating phase.

The invention relates to a method for restoring the performance of a vanadium redox flow battery module in a battery system, the method comprising the following steps in the order indicated: identifying at least one degraded battery module; switching off the pumps of the at least one degraded battery module at a time t1; switching on the pumps of the at least one degraded battery module at a time t2; wherein the length of the time interval t=t2t1 is selected such that, at the time t2, a terminal voltage of the degraded battery module is negative, but overcharging of the electrolyte located in the cell assembly of the degraded battery module is avoided, and wherein these steps, with the exception of the first step, take place while the battery system is being discharged.