Membrane electrode assembly for fuel and process for producing the same

A process for an membrane electrode assembly for a fuel cell composed of a pair of electrode catalyst layers and an electrolyte membrane sandwiched between the electrode catalyst layers configured so that the catalyst of at least one surface of the electrode catalyst layers enters in the electrolyte membrane whereby the electrode catalyst layer and the electrolyte membrane are unified with each other, which comprises:

• dissolving the catalyst making up the electrode catalyst layer in a polar solvent and then dispersing the catalyst in an ion conductive polymer solution to prepare a slurry having a viscosity of from 5,000 to 25,000 mPa.s,
• directly applying the resulting slurry onto at least one surface of the electrolyte membrane, followed by heating under a pressure to form the electrode catalyst layer or layers, and
• hating the slurry under a pressure to allow at least parts of the catalysts for entering in said electrolyte membrane during the heating under a pressure whereby said electrode catalyst layer and said electrolyte membrane are unified with each other.

A process for an membrane electrode assembly for a fuel cell composed of a pair of electrode catalyst layers and an electrolyte membrane sandwiched between the electrode catalyst layers configured so that the catalyst of at least one surface of the electrode catalyst layers enters in the electrolyte membrane whereby the electrode catalyst layer and the electrolyte membrane are unified with each other, which comprises:

• dispersing the catalyst making up the electrode catalyst layer in an organic solvent soluble in the electrolyte membrane to prepare a slurry of the catalyst dispersed in the organic solvent having a viscosity of from 5,000 to 25,000 mPa.s,
• directly applying the resulting slurry onto at least one surface of the electrolyte membrane, followed by heating under a pressure to form the electrode catalyst layer or layers, and
• heating the slurry under a pressure to allow at least parts of the catalysts for entering in said electrolyte membrane during the heating under a pressure whereby said electrode catalyst layer and said electrolyte membrane are unified with each other.

A process for an membrane electrode assembly for a fuel cell composed of a pair of electrode catalyst layers and an electrolyte membrane sandwiched between the electrode catalyst layers is configured so that the catalyst of at least one surface of the electrode catalyst layers enters in the electrolyte membrane whereby the electrode catalyst layer and the electrolyte membrane are unified with each other, which comprises:

• dissolving the catalyst making up the electrode catalyst layer in a polar solvent and then dispersing the catalyst in an ion conductive polymer solution to prepare a slurry having a viscosity of from 5,000 to 25,000 mPa.s,
• directly applying the resulting slurry onto at least one surface the diffusion layer laminated on both sides of the membrane electrode assembly, applying the electrolyte membrane onto the applied surface of the slurry, followed by heating under a pressure to form the electrode catalyst layer or layers, and
• heating the slurry under a pressure to allow at least parts of the catalysts for entering in said electrolyte membrane during the heating under a pressure whereby said electrode catalyst layer and said electrolyte membrane are unified with each other.