Electrolyte membrane-electrode assembly for fuel cells, and method for producing same

Abstract

An electrolyte membrane-electrode assembly is provided with: a solid polymer electrolyte membrane; and an anode-side electrode and a cathode-side electrode that sandwich the solid polymer electrolyte membrane. The cathode-side electrode has smaller planar dimensions than the anode-side electrode. In the electrolyte membrane-electrode assembly, a resin frame member is provided around the outer periphery of the solid polymer electrolyte membrane. The resin frame member is bonded to the cathode-side electrode by having only the outer peripheral portion of the cathode-side electrode being impregnated with the inner peripheral portion of the resin frame member.

1 . A fuel cell membrane electrode assembly comprising:
 a solid polymer electrolyte membrane and a first electrode and a second electrode provided on both sides of the solid polymer electrolyte membrane, the first electrode and the second electrode each including an electrode catalyst layer and a gas diffusion layer, an outer size of the first electrode being smaller than an outer size of the second electrode,   the membrane electrode assembly further comprising:   a resin frame member provided around the solid polymer electrolyte membrane; and   an impregnation portion for joining the resin frame member and at least one of an outer marginal portion of the first electrode and an outer marginal portion of the second electrode together, by impregnation of resin in a thickness direction of the resin frame member.   
     
     
         2 . The fuel cell membrane electrode assembly according to  claim 1 , wherein in the impregnation portion, the outer marginal portion of the first electrode is impregnated with an inner circumferential portion of the resin frame member, and the inner circumferential portion of the resin frame member is joined to the first electrode. 
     
     
         3 . The fuel cell membrane electrode assembly according to  claim 2 , wherein the resin frame member includes an inner extension, and a thickness of the inner extension is smaller than a thickness of the outer end of the resin frame member; and
 the inner extension has the inner marginal portion for impregnation of the outer marginal portion of the first electrode.   
     
     
         4 . The fuel cell membrane electrode assembly according to  claim 1 , wherein an outer end of the gas diffusion layer of the first electrode and an outer end of the gas diffusion layer of the second electrode are impregnated with resin such that resin impregnation portions as the impregnation portion joining the membrane electrode assembly and the resin frame member together are provided. 
     
     
         5 . The fuel cell membrane electrode assembly according to  claim 4 , wherein the resin impregnation portions are provided over entire circumferences of the outer ends of the gas diffusion layers, respectively. 
     
     
         6 . The fuel cell membrane electrode assembly according to  claim 4 , wherein the resin impregnation portions include a frame shaped first resin member placed over an entire circumference of the gas diffusion layer of the first electrode and a frame shaped second resin member (placed over an entire circumference of the gas diffusion layer of the second electrode. 
     
     
         7 . The fuel cell membrane electrode assembly according to  claim 4 , wherein the resin impregnation portions include:
 a frame shaped first resin protrusion provided integrally with the resin frame member, and placed over an entire circumference of the gas diffusion layer of the first electrode; and   a frame shaped second resin protrusion provided integrally with the resin frame member, and placed over an entire circumference of the gas diffusion layer of the second electrode.   
     
     
         8 . The fuel cell membrane electrode assembly according to  claim 1 , wherein an outer end of the gas diffusion layer of the second electrode is impregnated with resin to form a resin impregnation portion as the impregnation portion joining the membrane electrode assembly and the resin frame member together. 
     
     
         9 . The fuel cell membrane electrode assembly according to  claim 8 , wherein the resin impregnation portion is provided over an entire circumference of the outer end of the gas diffusion layer. 
     
     
         10 . The fuel cell membrane electrode assembly according to  claim 8 , wherein the resin impregnation portion includes a frame shaped resin member placed over an entire circumference of the gas diffusion layer of the second electrode. 
     
     
         11 . A method of producing a fuel cell membrane electrode assembly, the membrane electrode assembly comprising a solid polymer electrolyte membrane and a first electrode and a second electrode provided on both sides of the solid polymer electrolyte membrane, the first electrode and the second electrode each including an electrode catalyst layer and a gas diffusion layer, an outer size of the first electrode being smaller than an outer size of the second electrode,
 the method comprising the steps of:   forming the first electrode and the second electrode on both sides of the solid polymer electrolyte membrane;   forming a resin frame member; and   overlapping an outer marginal portion of the first electrode and an inner marginal portion of the resin frame member with each other and heating the overlapped portions of the first electrode and the resin frame member to impregnate the outer marginal portion of the first electrode with the inner marginal portion of the resin frame member and join the resin frame member around the solid polymer electrolyte membrane.   
     
     
         12 . A method of producing a fuel cell membrane electrode assembly, the membrane electrode assembly comprising a solid polymer electrolyte membrane and a first electrode and a second electrode provided on both sides of the solid polymer electrolyte membrane, the first electrode and the second electrode each including an electrode catalyst layer and a gas diffusion layer, an outer size of the first electrode being smaller than an outer size of the second electrode,
 the method comprising the steps of:   overlapping an outer marginal portion of the gas diffusion layer of the first electrode and an inner marginal portion of a resin frame member with each other and heating the overlapped portions of the gas diffusion layer of the first electrode and the resin frame member to impregnate the outer marginal portion of the first electrode with the inner marginal portion of the resin frame member and join the resin frame member to the first electrode;   forming the electrode catalyst layers on both surfaces of the solid polymer electrolyte membrane; and   combining the gas diffusion layer of the first electrode joined to the resin frame member and the gas diffusion layer of the second electrode on both sides of the solid polymer electrolyte membrane into one piece.   
     
     
         13 . A method of producing a fuel cell membrane electrode assembly, the membrane electrode assembly comprising a solid polymer electrolyte membrane and a first electrode and a second electrode provided on both sides of the solid polymer electrolyte membrane, the first electrode and the second electrode each including an electrode catalyst layer and a gas diffusion layer, an outer size of the first electrode being smaller than an outer size of the second electrode,
 the method comprising the steps of:   overlapping an outer marginal portion of the gas diffusion layer of the first electrode and an inner marginal portion of a resin frame member with each other and heating the overlapped portions of the gas diffusion layer of the first electrode and the resin frame member to impregnate the outer marginal portion of the first electrode with the inner marginal portion of the resin frame member and join the resin frame member to the first electrode;   forming the electrode catalyst layer on the gas diffusion layer of the second electrode and forming the electrode catalyst layer of the first electrode on one side of the solid polymer electrolyte membrane; and   combining the first electrode joined to the resin frame member and the second electrode on both sides of the solid polymer electrolyte membrane into one piece.