Local hydrophilic gas diffusion layer and fuel cell stack comprising the same

Abstract

The present invention provides a local hydrophilic gas diffusion layer configured to enhance the water removal performance of a fuel cell For this purpose, the present invention provides a gas diffusion layer in which a region under each of a pair of lands, which receives a clamping pressure of the fuel cell stack, is subjected to local hydrophilic treatment by a simple process, thereby enhancing the water removal performance of the fuel cell stack. In particular, the local hydrophilic gas diffusion layer has a first region under each land of the separator which receives the clamping pressure; and a second region under the gas channel of the separator, wherein the first region is subjected to hydrophilic treatment.

What is claimed is: 
     
         1 . A local hydrophilic gas diffusion layer configured to receive a clamping pressure of a fuel cell stack from a separator including a pair of lands that form a gas channel, the local hydrophilic gas diffusion layer comprising:
 a first region under each land of the separator which receives the clamping pressure; and   a second region under the gas channel of the separator,   wherein the first region is subjected to hydrophilic treatment.   
     
     
         2 . The local hydrophilic gas diffusion layer of  claim 1 , wherein the first region has pores having a size smaller than that of pores of the second region, the size of pores of the first region being reduced due to deformation by the clamping pressure of the fuel cell stack. 
     
     
         3 . The local hydrophilic gas diffusion layer of  claim 1 , wherein the first region is subjected to hydrophilic treatment by constituting the separator as a first electrode, providing a second electrode at the opposite side of the first electrode, and applying an alternating current water based fluid. 
     
     
         4 . A fuel cell stack comprising:
 a membrane electrode assembly including an electrolyte membrane and a catalyst layer disposed on each of both sides of the electrolyte membrane;   a separator including a gas channel; and   a local hydrophilic gas diffusion layer stacked between the membrane electrode assembly and the separator to receive a clamping pressure of the fuel cell stack from a pair of lands formed on the separator and including a first region under each land of the separator, which is subjected to hydrophilic treatment, and a second region under the gas channel, which is not subjected to hydrophilic treatment.   
     
     
         5 . The fuel cell stack of  claim 4 , wherein the first region has pores having a size smaller than that of pores of the second region, the size of pores of the first region being reduced due to deformation by the clamping pressure of the fuel cell stack. 
     
     
         6 . The fuel cell stack of  claim 4 , wherein the first region is subjected to hydrophilic treatment by constituting the separator as a first electrode, providing a second electrode at the opposite side of the first electrode, and applying an alternating current to a water based fluid. 
     
     
         7 . The fuel cell stack of  claim 4 , further comprising a microporous layer stacked between the local hydrophilic gas diffusion layer and the membrane electrode assembly. 
     
     
         8 . The fuel cell stack of  claim 4 , wherein the separator comprises a fixing portion to fix the relative location of the separator and the local hydrophilic gas diffusion layer. 
     
     
         9 . A gas diffusion layer comprising:
 a first region under each land of the separator which receives a clamping pressure of a fuel cell stack from a pair of lands protruding from a separator, the pair of lands forming a gas channel; and   a second region under the gas channel of the separator,   wherein the first region is subjected to hydrophilic treatment.   
     
     
         10 . The gas diffusion layer of  claim 9 , wherein the first region has pores having a size smaller than that of pores of the second region, the size of pores of the first region being reduced due to deformation by the clamping pressure of the fuel cell stack. 
     
     
         11 . The gas diffusion layer of  claim 9 , wherein the first region is subjected to hydrophilic treatment by constituting the separator as a first electrode, providing a second electrode at the opposite side of the first electrode, and applying an alternating current to a water based fluid. 
     
     
         12 . The gas diffusion layer of  claim 9 , wherein the gas diffusion layer is a local hydrophilic gas diffusion layer.