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.

A fuel cell system includes a removal treatment execution unit configured to execute an oxide layer removal treatment that removes an oxide layer generated on a catalyst of a fuel cell. The removal treatment execution unit is configured to execute the oxide layer removal treatment by adjusting a voltage of the fuel cell to be within a predetermined second voltage range lower than a predetermined first voltage range that is lower than an open-circuit voltage, when an operation of the fuel cell system shifts from a first operation, where a current value of the fuel cell is zero and the flow rate is controlled to maintain the voltage of the fuel cell within the first voltage range, to a second operation, where the current value is larger than zero and the flow rate is controlled in response to an output request to the fuel cell.

A fuel cell reversal event is diagnosed by integrating current density via a controller in response to determine an accumulated charge density. The controller executes a control action when the accumulated charge density exceeds a threshold, including recording a diagnostic code indicative of event severity. The control action may include continuing stack operation at reduced power capability when the accumulated charge density exceeds a first threshold and shutting off the stack when the accumulated charge density exceeds a higher second threshold. The event may be detected by calculating a voltage difference between an average and a minimum cell voltage, and then determining if the difference exceeds a voltage difference threshold. The charge density thresholds may be adjusted based on age, state of health, and/or temperature of the fuel cell or stack. A fuel cell system includes the stack and controller.

A method for reducing cell degradation in a fuel cell system includes adding oxygen-containing gas to a fuel in the anode chamber to prevent an increase in a cell voltage above a predetermined maximum value.

The invention relates to a fuel cell (2) comprising at least one membrane/electrode unit (10) comprising a first electrode and a second electrode, which electrodes are separated from one another by a membrane, and comprising at least one polar plate (40) which comprises a first distribution region (50) for distributing a fuel to the first electrode and a second distribution region (60) for distributing an oxidation agent to the second electrode. The first electrode and the second electrode of the at least one membrane electrode unit (10) are electrically connected by means of a conductor (90). The invention also relates to a fuel cell stack (5) which comprises a plurality of the claimed fuel cells (2).

A method for starting a fuel cell and to a fuel cell system which is configured to carry out the method. The fuel cell includes electrically conductive bipolar plates, arranged between which there is in each case a cathode, including a fluid-conducting cathode space, a membrane and an anode, including a fluid-conducting anode space. There is provision that the method includes the following steps in the specified order: purging the anode space with a fluid in order to expel fuel, impressing electricity on a unit composed of the cathode (2k)/membrane (1)/anode (2a) by applying a current and/or a voltage, wherein the fluid is applied to the anode space or continues to be so, switching off the electricity, and introducing a fuel into the anode space.

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.

A method for recovering fuel cell performance by regenerating electrode characteristics through electrode reversal in order to partially recover performance of a degraded polymer electrolyte fuel cell is provided. The method includes reversing electrodes by supplying an anode of a degraded fuel cell stack with air and supplying a cathode thereof with hydrogen and performing a pulse operation by applying current to the reversed electrodes.

A fuel cell recovery control system and method are provided to supply hydrogen to the cathode of a fuel cell stack to remove an oxide film formed on a platinum surface of the cathode. The performance of the fuel cell stack is recovered in accordance with the oxide film removal. In addition, electric power generated during the performance recovery of the fuel cell stack is consumed in an inverter and, as such, overcharge of a battery is prevented.

A fuel cell module is configured or operated, or both, such that after a shut down procedure a fuel cell stack is discharged and has its cathode electrodes at least partially blanketed with nitrogen during at least some periods of time. If the fuel cell module is restarted in this condition, electrochemical reactions are limited and do not quickly re-charge the fuel cell stack. To decrease start up time, air is moved into the cathode electrodes before the stack is re-charged. The air may be provided by a pump, fan or blower driven by a battery or by the flow or pressure of stored hydrogen. For example, an additional fan or an operating blower may be driven by a battery until the fuel cell stack is able to supply sufficient current to drive the operating blower for normal operation.