Fuel Cell System (Nissan Motor Co.)

PATENT
Fuel Cell System (Nissan Motor Co.)
European Patent EP2067203
Inventors:
Nagahara, Yoshiki C/O Nissan Motor Co. (Ltd.Intellectual Property Department560-2 Okatsukoku, Atsugi-Shi, Kanagawa 243-0192, Jp)
Simoi, Ryoichi C/O Nissan Motor Co. (Ltd.Intellectual Property Department560-2 Okatsukoku, Atsugi-Shi, Kanagawa 243-0192, Jp)
Application Number:
EP20070804941
Publication Date:
01/23/2013
Assignee:
Nissan Motor Co., Ltd. (2, Takara-cho Kanagawa-ku Yokohama-shi,, Kanagawa 221-0023, JP)
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for recovering catalytic activity of the electrode catalyst layer of a fuel cell system and to a fuel cell system and in particular to a fuel cell system comprising a solid polymer membrane as an electrolyte membrane using said method.
2. Description of the Related Art
In a general fuel cell system, after power general performance is decreased due to impurities in a fuel cell, the polarities of the fuel cell are reversed to draw out a current and to move and discharge impurity ions from an electrolyte membrane (refer to, for example, Japanese patent No.
3475869).
WO 03/083975 A discloses a method and device for rejuvenating a fuel cell or fuel cell stack, whereby cell poisons are eliminated from the cathode and anode catalyst layer. In order to achieve this rejuvenating effect, the fuel cell stack is provided with a controller, varying the voltage level and thus directly influencing and furthermore increasing the current of the fuel cell.
US 2004/247510 A1 describes a method and apparatus for removing contaminants from a hydrogen processor feed stream, as in a fuel cell power plant. Inlet oxidant, typically air, required by a catalytic hydrogen processor in a fuel processor for a fuel cell stack assembly in the power plant, may contain contaminants such as SO2 and the like. A cleansing arrangement, which includes an accumulator/degasifier acting as a scrubber, and possibly also a water transfer device, receives the inlet oxidant and provides the desired cleansing of contaminants. Water in the water transfer device and in the accumulator/degasifier serves to dissolve the water-soluble contaminants and cleanse them from the oxidant stream. The cleansed oxidant stream is then delivered to the hydrogen processor and to the fuel cell assembly, with minimal inclusion of detrimental contaminants such as sulphur.
SUMMARY OF THE INVENTION
However, in such a general fuel cell system, impurities adsorbed on the surfaces of a catalyst cannot be removed.
The present invention has been achieved in consideration of the above-mentioned problem, and it is an object of the present invention to remove impurities such as atmospheric sulfur compounds.
In accordance with an embodiment of the present invention, a method for recovering catalytic activity of the electrode catalyst layers of a fuel cell system is described, the fuel cell system comprising a fuel cell in which a plurality of unit cells, each having an electrolyte membrane held between electrode catalyst layers, are stacked and an ECU. According to said method, the ECU decreases the temperature of the fuel cell or controls a humidifier to increase the water content of the oxidizer gas to be supplied to the fuel cell and thereby increases the amount of water discharged from the fuel cell to a predetermined amount or more.
In accordance with another embodiment of the present invention, a fuel cell system includes a fuel cell in which a plurality of unit cells, each having an electrolyte membrane held between electrode catalyst layers, are stacked, and an ECU for recovering the catalytic activity of the electrode catalyst layers as outlined above.
In the fuel cell system, the amount of water discharged from the electrode catalyst layers is increased to a predetermined amount or more so that sulfur compounds adsorbed on the catalyst surfaces can be removed.
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