Method for manufacturing membrane-electrode assembly

1. A method for manufacturing a membrane-electrode assembly, comprising:

a reinforcing member disposing step of disposing a reinforcing member, whose frame portion is formed to surround an opening of the reinforcing member, on a polymer electrolyte membrane such that the frame portion covers a peripheral portion of at least one surface of the polymer electrolyte membrane;

a catalyst layer applying step of applying a coating of a catalyst layer on an entire surface of the polymer electrolyte membrane, which surface is exposed from the opening of the reinforcing member, such that the catalyst layer spreads outside the opening when viewed from a thickness direction of the catalyst layer; and

a gas diffusion layer disposing step of disposing a gas diffusion layer such that the gas diffusion layer covers the catalyst layer,

wherein the reinforcing member disposing step, the catalyst layer applying step, and the gas diffusion layer disposing step are performed in the stated order.

2. The method according to claim 1 , wherein in the catalyst layer applying step, the coating of the catalyst layer is applied by spraying.

3. The method according to claim 1 , further comprising:

a composite member forming step of forming a composite member including the reinforcing member and a covering member which has a substantially same planar shape as the reinforcing member and covers one surface of the reinforcing member; and

a covering member removing step of removing the covering member from the reinforcing member after applying the coating of the catalyst layer, wherein:

in the reinforcing member disposing step, the composite member is disposed such that the reinforcing member is located closer to the polymer electrolyte membrane than the covering member; and

in the catalyst layer applying step, the coating of the catalyst layer is applied so as to spread outside an opening of the composite member when viewed from the thickness direction of the catalyst layer.

4. The method according to claim 3 , wherein in the composite member forming step, the composite member is formed by bonding two resin sheets to each other and stamping them.

5. The method according to claim 1 , wherein:

the reinforcing member disposing step includes a first reinforcing member disposing step of disposing a first reinforcing member, whose frame portion is formed to surround an opening of the first reinforcing member, on a first polymer electrolyte membrane such that the frame portion covers a peripheral portion of at least one surface of the first polymer electrolyte membrane, and a second reinforcing member disposing step of disposing a second reinforcing member, whose frame portion is formed to surround an opening of the second reinforcing member, on the second polymer electrolyte membrane such that the frame portion covers a peripheral portion of at least one surface of the second polymer electrolyte membrane; and

the catalyst layer applying step includes a first catalyst layer applying step of applying a coating of a first catalyst layer on at least an entire surface of the first polymer electrolyte membrane which surface is exposed from the opening of the first reinforcing member, and a second catalyst layer applying step of applying a coating of a second catalyst layer on at least an entire surface of the second polymer electrolyte membrane which surface is exposed from the opening of the second reinforcing member,

the method further comprising

a polymer electrolyte membrane contacting step of causing a surface, on which the coating of the first catalyst layer is not applied, of the first polymer electrolyte membrane on which the coating of the first catalyst layer is applied and a surface, on which the coating of the second catalyst layer is not applied, of the second polymer electrolyte membrane on which the coating of the second catalyst layer is applied to contact each other.

6. The method according to claim 5 , further comprising:

a first composite member forming step of forming a first composite member including the first reinforcing member and a first covering member which has a substantially same planar shape as the first reinforcing member and covers one surface of the first reinforcing member;

a second composite member forming step of forming a second composite member including the second reinforcing member and a second covering member which has a substantially same planar shape as the second reinforcing member and covers one surface of the second reinforcing member;

a first covering member removing step of removing the first covering member from the first reinforcing member after applying the coating of the first catalyst layer; and

a second covering member removing step of removing the second covering member from the second reinforcing member after applying the coating of the second catalyst layer, wherein:

in the first reinforcing member disposing step, the first composite member is disposed such that the first reinforcing member is located closer to the first polymer electrolyte membrane than the first covering member;

in the second reinforcing member disposing step, the second composite member is disposed such that the second reinforcing member is located closer to the second polymer electrolyte membrane than the second covering member;

in the first catalyst layer applying step, the coating of the first catalyst layer is applied so as to spread over an opening of the first composite member and a region outside and surrounding the opening; and

in the second catalyst layer applying step, the coating of the second catalyst layer is applied so as to spread over an opening of the second composite member and a region outside and surrounding the opening.

7. The method according to claim 5 , further comprising:

a first polymer electrolyte membrane holding step of holding the first polymer electrolyte membrane on one surface of a first backing member; and

a second polymer electrolyte membrane holding step of holding the second polymer electrolyte membrane on one surface of a second backing member, wherein:

in the first reinforcing member disposing step, the first composite member is disposed on the first polymer electrolyte membrane such that the first reinforcing member covers a surface of the first polymer electrolyte membrane which surface is not held by the first backing member; and

in the second reinforcing member disposing step, the second composite member is disposed on the second polymer electrolyte membrane such that the second reinforcing member covers a surface of the second polymer electrolyte membrane which surface is not held by the second backing member,

the method further comprising:

a first backing member removing step of, before the polymer electrolyte membrane contacting step, removing the first backing member from the first polymer electrolyte membrane on which the coating of the first catalyst layer is applied; and

a second backing member removing step of, before the polymer electrolyte membrane contacting step, removing the second backing member from the second polymer electrolyte membrane on which the coating of the second catalyst layer is applied.