Solid polymer electrolyte fuel cell

Abstract

The present invention provides a solid polymer electrolyte fuel cell comprising a fuel cell stack formed by laminating a plurality of fuel cell units each of which includes a fuel electrode, an oxidant electrode, and a solid polymer electrolyte membrane interposed between the fuel and oxidant electrodes. The fuel cell unit is operable to generate an electric power through an electrochemical reaction between a first gas supplied to the side of the fuel electrode and a second gas supplied to the side of the oxidant electrode. In this fuel cell, the first gas supplied to the side of the fuel electrode and the second gas supplied to the side of the oxidant electrode are adapted to flow generally in opposite directions in the fuel cell stack, so that a water created on the side of oxidant electrode is reciprocally moved between the fuel electrode and the oxidant electrode to increase a water holding region in the solid polymer electrolyte membrane. The fuel cell of the present invention can improve fuel cell characteristics without providing any humidifier.

1 . A method for operating a solid polymer electrolyte fuel cell comprising the steps of:
 forming a fuel cell stack by laminating a plurality of fuel cell units each of which includes a fuel electrode, an oxidant electrode, and a solid polymer electrolyte membrane interposed between said fuel and oxidant electrodes,   supplying a pure hydrogen gas to the side of said fuel electrode without humidification from its supply source,   supplying a pure oxygen gas to the side of said oxidant electrode without humidification from its supply source,   generating electric power through an electrochemical reaction between the pure hydrogen gas and the pure oxygen gas, and   flowing said hydrogen gas and said oxygen gas in opposite directions in said fuel cell stack, to reciprocally move water created on the side of the oxidant electrode between said fuel and oxidant electrodes through the solid polymer electrolyte membrane to increase a water holding region in said solid polymer electrolyte membrane.   
     
     
         2 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 1 , wherein in said forming step, the solid polymer electrolyte fuel cell is formed to include:
 a condenser; and   a gas discharge port for discharging at least said oxygen gas from the side of said oxidant electrode, wherein said method further comprises the steps of:   connecting said gas discharge port to said oxygen gas supply path so as to form a closed circulation path, and   providing said condenser in said closed circulation path.   
     
     
         3 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 1 , wherein in said forming step, the solid polymer electrolyte fuel cell is formed to include a condenser having an outlet side, an oxygen gas supply port for supplying said oxygen gas of said oxidant electrode, and a gas discharge path for discharging at least said oxygen gas from the side of said oxidant electrode from the oxygen gas supply means, wherein said method further comprises the steps of:
 connecting said gas discharge path and said oxygen gas supply means to said condenser, and   connecting the outlet side of said condenser to said oxygen gas supply port, so as to form a closed circulation path.   
     
     
         4 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 2 , wherein in said forming step, the solid polymer electrolyte fuel cell is formed to include a gas discharge port provided on the side of said fuel electrode, wherein in said connecting step, said closed circulation path is provided on the side of said oxidant electrode, and wherein the gas discharge port provided on the side of said fuel electrode is closed. 
     
     
         5 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 2 , further comprising the step of containing condensed water condensed by said condenser. 
     
     
         6 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 2 , further comprising the step of controlling a cooling medium of said condenser in a temperature range of −30° C. to +10° C. with respect to an operating temperature of said fuel cell. 
     
     
         7 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 2 , further comprising the step of controlling the volume of the gas circulated through said closed circulation path in the range of 2 to 10 times greater than a theoretical gas volume required for electrochemically generating electric power. 
     
     
         8 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 1 , wherein in said forming step, said solid polymer electrolyte membrane has a thickness of 10 to 50 μm. 
     
     
         9 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 2 , further comprising the steps of containing condensed water condensed by said condenser, in a container, and absorbing the condensed water, using an absorber included in the container. 
     
     
         10 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 9 , the step of allowing the circulation gas in said closed circulation path to be smoothly transferred through said condenser while contacting said absorber. 
     
     
         11 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 9 , further comprising the steps of cooling the circulation gas in said closed circulation path, using said condenser, and using said container to contain condensed water condensed in said cooling step. 
     
     
         12 . The method for operating a solid polymer electrolyte fuel cell as defined in  claim 2 , wherein in said connecting step, said closed circulation path bypasses said condenser.