Method of manufacturing electrode of electrode-electrolyte membrane joint body for fuel cell and electrode for fuel cell

Abstract

A paste-like ink is prepared by dissolving camphor in an alcoholic solvent and dispersing fine carbon particles with a catalyst carried thereon in the solvent (step S 100 ). A sheet-like electrode-forming member is formed on an electrolyte membrane by screen printing the paste-like ink thus obtained (step S 102 ). The electrode-forming member is dried at 80° C. for one hour, in order to deposit camphor included in the electrode-forming member as a pore-forming agent (step S 104 ). The electrode-forming member and the electrolyte membrane are joined with each other by hot pressing (step S 106 ). The joint body of the electrode-forming member and the electrolyte membrane is dried under vacuum at 80° C. for three hours, in order to sublimate and remove camphor depositing in the electrode-forming member (step S 108 ). This gives an electricity-generating layer that is a joint body of an electrode having a plurality of pores and the electrolyte membrane. The manufacturing process of the invention thus gives a joint body of an electrode having sufficient gas permeability and electrical conductivity and an electrolyte membrane.

What is claimed is:  
     
         1 . A method of manufacturing an electrode for a fuel cell, said electrode having a plurality of pores and comprising carbon particles with a catalyst carried thereon, said method comprising the steps of: 
 (a) preparing an electrode-forming member comprising said carbon particles and a pore-forming agent that can be sublimed; and 
 (b) subliming said pore-forming agent by setting said electrode-forming member under a predetermined condition.  
   
     
     
         2 . A method in accordance with    claim 1   , wherein said step (a) further comprises the steps of: 
 (a1) dissolving said pore-forming agent into a solvent that allows dissolution of said pore-forming agent and dispersing said carbon particles in the solvent, so as to prepare a solution for forming a paste-like electrode;    (a2) forming the solution prepared in said step (al) into a predetermined shape of said electrode-forming member; and 
 (a3) depositing said pore-forming agent dissolved in the solution formed into the predetermined shape in said step (a2).  
   
     
     
         3 . A method in accordance with    claim 2   , wherein said step (a3) further comprises the step of: 
 drying the solution formed into the predetermined shape, so as to make concentration of said pore-forming agent in the solution equal to or higher than its solubility, thereby allowing deposition of said pore-forming agent.    
     
     
         4 . A method in accordance with    claim 2    or    3   , wherein said steps (a1) and (a2) are carried out at a predetermined temperature that allows solubility of said pore-forming agent in the solvent to be equal to or higher than a predetermined level.  
     
     
         5 . A method of manufacturing an electrode for a fuel cell, said electrode having a plurality of pores and comprising carbon particles with a catalyst carried thereon, said method comprising the steps of: 
 (a) dispersing said carbon particles in a solvent that can be freeze-dried, so as to prepare a solution for forming a paste-like electrode;    (b) forming the solution prepared in said step (a) into a predetermined shape of said electrode; and    (c) freeze-drying the solvent of the solution formed into the predetermined shape in said step (b) under a specified condition.    
     
     
         6 . A method of manufacturing an electrode-electrolyte membrane joint body for a fuel cell, said electrode-electrolyte membrane joint body being obtained by joining an electrode having a plurality of pores and comprising carbon particles with a catalyst carried thereon with an electrolyte membrane mainly composed of a polymer electrolyte, said method comprising the steps of: 
 (a) preparing an electrode-forming member comprising said carbon particles and a pore-forming agent that sublimes under a specified condition;    (b) joining said electrode-forming member prepared in said step (a) with said electrolyte membrane under a certain condition other than the specified condition to yield a joint body; and    (c) subliming said pore-forming agent by setting said joint body of said electrode-forming member and said electrolyte membrane under the specified condition.    
     
     
         7 . A method in accordance with    claim 6   , wherein said step (a) further comprises the steps of: 
 (a1) dissolving said pore-forming agent into a solvent that allows dissolution of said pore-forming agent and dispersing said carbon particles in the solvent, so as to prepare a solution for forming a paste-like electrode;    (a2) forming the solution prepared in said step (a1) into a predetermined shape of said electrode-forming member; and 
 (a3) depositing said pore-forming agent dissolved in the solution formed into the predetermined shape in said step (a2).  
   
     
     
         8 . A method in accordance with    claim 7   , wherein said step (a3) further comprises the step of: 
 drying the solution formed into the predetermined shape, so as to make concentration of said pore-forming agent in the solution equal to or higher than its solubility, thereby allowing deposition of said pore-forming agent.    
     
     
         9 . A method in accordance with    claim 7    or    8   , wherein said steps (a1) and (a2) are carried out at a predetermined temperature that allows solubility of said pore-forming agent in the solvent to be equal to or higher than a predetermined level.  
     
     
         10 . A method of manufacturing an electrode-electrolyte membrane joint body for a fuel cell, said electrode-electrolyte membrane joint body being obtained by joining an electrode having a plurality of pores and comprising carbon particles with a catalyst carried thereon with an electrolyte membrane mainly composed of a polymer electrolyte, said method comprising the steps of: 
 (a) dispersing said carbon particles in a solvent that can be freeze-dried, so as to prepare a solution for forming a paste-like electrode;    (b) forming the solution prepared in said step (a) into a predetermined shape of said electrode on said electrolyte membrane; and    (c) freeze-drying the solvent by setting the solution formed into the predetermined shape in said step (b) under a specified condition.    
     
     
         11 . An electrode for a fuel cell, said electrode comprising carbon particles with a catalyst carried thereon and a space of three-dimensional diversified structure that is made of a plurality of pores having various diameters.  
     
     
         12 . An electrode in accordance with    claim 11   , wherein said pores have diameters ranging from 0.02 to 0.3 μm.