Fuel cell-use carbon fiber woven fabric, electrode element, fuel cell mobile unit, and production method for fuel cell-use carbon fiber woven fabric

Abstract

A fuel cell-use carbon fiber woven fabric, especially a carbon fiber woven fabric preferably used for the electrode diffusion layer of an electrode element in a fuel cell. The electrode diffusion layer of an electrode element in a fuel cell, requiring conductivity, gas diffusing/permeating features, and strength that withstands handling, is formed from carbon fiber woven fabrics as is widely known. The conventional carbon fiber woven fabric poses such problems that deformation by compression is large, the dimension of a fuel cell is significantly changed by pressurizing, irregularities by weave texture are large, and contact resistance is large. A carbon fiber woven fabric used for a fuel cell-use carbon fiber woven fabric has an average size of warps and wefts constituting the woven fabric of 0.005-0.028 g/m, and a woven density of the warps and/or wefts of 20 pieces/cm.

1 . A carbon fiber woven fabric for a fuel cell, characterized in that the average fineness of the warp yarns and the weft yarns constituting the woven fabric is in the range of 0.005 to 0.028 g/m, and that the weave density of the warp yarns and/or the weft yarns is not less than 20 yarns/cm.  
     
     
         2 . A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the unit weight of the woven fabric is in the range of 50 to 150 g/m 2 .  
     
     
         3 . A carbon fiber woven fabric for a fuel cell, according to  claim 1  wherein the thickness of the woven fabric is in the range of 0.1 to 0.3 mm.  
     
     
         4 . A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the value of N×W is not less than 0.6 where N (yarns/cm) is the weave density of the warp yarns and/or the weft yarns and W (cm/yarn) is the yarn width.  
     
     
         5 . A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the crush value of the woven fabric under compression is not more than 0.15 mm.  
     
     
         6  A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the warp yarns and/or the weft yarns are spun yarns.  
     
     
         7  A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the electric resistance of the woven fabric is not more than 30 mΩcm 2 , and the differential pressure caused when 14 cm 3 /cm 2 /sec of air is passed through the woven fabric in the thickness direction is not more than 5 mm Aq.  
     
     
         8 . A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the ratio of the number of oxygen atoms to the number of carbon atoms on the carbon fiber surfaces of the woven fabric is not less than 0.06 and less than 0.17.  
     
     
         9 . A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the woven fabric contains carbon black on its surfaces and/or inside.  
     
     
         10 . A carbon fiber woven fabric for a fuel cell, according to  claim 1 , wherein the woven fabric contains a water-repellent substance.  
     
     
         11 . An electrode element for a fuel cell, formed of the carbon fiber woven fabric as set forth in any one of claims  1  through  10 .  
     
     
         12 . An electrode element for a fuel cell, comprising an electrode diffusion layer formed of the carbon fiber woven fabric as set forth in any one of claims  1  through  10 .  
     
     
         13 . An electrode element for a fuel cell, according to  claim 12 , wherein the electrode diffusion layer has a catalyst layer disposed thereon in layer.  
     
     
         14 . An electrode element for a fuel cell, according to  claim 12 , wherein the electrode diffusion layer has a catalyst layer and a polymer electrolyte membrane disposed thereon in layers.  
     
     
         15 . A fuel cell comprising the electrode element as set forth in  claim 11 .  
     
     
         16 . A fuel cell, according to  claim 15 , wherein a grooved separator is provided on the electrode element.  
     
     
         17 . A mobile unit mounted with the fuel cell as set forth in  claim 15 .  
     
     
         18 . A method for producing a carbon fiber woven fabric for a fuel cell, comprising a pressurization step of pressurizing a precursor fiber woven fabric composed of carbon precursor fibers in the thickness direction, and a step of carbonizing the precursor fiber woven fabric.  
     
     
         19 . A method for producing a carbon fiber woven fabric for a fuel cell, according to  claim 18 , wherein the pressurization step is carried out at a heating temperature of not more than 300° C. at a pressure of 5 to 500 kg/cm.  
     
     
         20 . A method for producing a carbon fiber woven fabric for a fuel cell, according to  claim 18  or  19 , wherein the carbon precursor fibers are oxidized acrylic fibers.