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 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 said fuel and oxidant electrodes, said fuel cell unit being operable to generate an electric power through an electrochemical reaction between a first gas supplied to the side of said fuel electrode and a second gas supplied to the side of said oxidant electrode, wherein 
 said first gas supplied to the side of said fuel electrode and said second gas supplied to the side of said oxidant electrode are adapted to flow generally in opposite directions in said fuel cell stack, so that a water created on the side of oxidant electrode is reciprocally moved between said fuel and oxidant electrodes to increase a water holding region in said solid polymer electrolyte membrane.    
   
   
       2 . A solid polymer electrolyte fuel cell as defined in  claim 1 , which includes a gas supply path for supplying said second gas to the side of said oxidant electrode, and a gas discharge port for discharging at least said second gas from the side of said oxidant electrode, wherein said gas discharge port is connected to said second gas supply path so as to form a closed circulation path, and a condenser is provided in said closed circulation path.  
   
   
       3 . A solid polymer electrolyte fuel cell as defined in  claim 1 , which includes a second gas supply port for supplying said second gas of said oxidant electrode, and a gas discharge path for discharging at least said second gas from the side of said oxidant electrode, wherein said gas discharge path and second gas supply source are connected to a condenser, and the outlet side of said condenser is connected to said second gas supply port, so as to form a closed circulation path.  
   
   
       4 . A solid polymer electrolyte fuel cell as defined in  claim 2 , wherein said closed circulation path is not provided on the side of said fuel electrode, wherein a gas discharge port provided on the side of said fuel electrode is closed.  
   
   
       5 . A solid polymer electrolyte fuel cell as defined in  claim 1 , wherein said first gas to be supplied to the side of said fuel electrode is a pure hydrogen gas, and said second gas to be supplied on the side of said oxidant electrode is a pure oxygen gas.  
   
   
       6 . A solid polymer electrolyte fuel cell as defined in  claim 2 , which includes means for containing a condensed water condensed by said condenser.  
   
   
       7 . A solid polymer electrolyte fuel cell as defined in  claim 2 , which includes temperature control means for 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.  
   
   
       8 . A solid polymer electrolyte fuel cell as defined in  claim 2 , which includes flow-volume control means for 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 the electric power.  
   
   
       9 . A solid polymer electrolyte fuel cell as defined in  claim 1 , wherein said solid polymer electrolyte membrane has a thickness of 10 to 50 μm.  
   
   
       10 . A solid polymer electrolyte fuel cell as defined in  claim 2 , which includes means for containing a condensed water condensed by said condenser, said containing means including means for absorbing the condensed water.  
   
   
       11 . A solid polymer electrolyte fuel cell as defined in  claim 10 , wherein said condenser further includes transfer means for allowing the circulation gas in said closed circulation path to be smoothly transferred through said condenser while contacting said absorbing means.  
   
   
       12 . A solid polymer electrolyte fuel cell as defined in  claim 10 , wherein said condenser includes cooling means for cooling the circulation gas in said closed circulation path, said cooling means being provided separately from said containing means, wherein said containing means is operable to contain a condensed water condensed by said cooling means.