Patent ID: 7807314

Claim:
A membrane electrode assembly for use in a solid polymer electrolyte fuel cell, the membrane electrode assembly comprising: a solid polymer electrolyte membrane having proton conductivity; a cathode electrode catalyst layer disposed on one side of the solid polymer electrolyte membrane; an anode electrode catalyst layer disposed on the other side of the solid polymer electrolyte membrane; two gas diffusion layers disposed on a side of the cathode electrode catalyst layer and a side of the anode electrode catalyst layer, respectively, with the sides facing away from the solid polymer electrolyte membrane; wherein the membrane electrode assembly comprises two intermediate layers comprising pores and disposed respectively between one of the electrode catalyst layers and the gas diffusion layer pairing therewith and between the other of the electrode catalyst layers and the gas diffusion layer pairing therewith, and the volume per unit area and per unit mass of the pores falling within a pore size range from 0.1 to 10 μm in the intermediate layer in the cathode side is larger than the volume per unit area and per unit mass of the pores falling within a pore size range from 0.1 to 10 μm in the intermediate layer in the anode side; and wherein the volume per unit area and per unit mass of the pores falling within the specified pore size range in the intermediate layer in the cathode side falls within a range from 1.7 to 4.3 μl/cm 2 /mg, and the volume per unit area and per unit mass of the pores falling within the specified pore size range in the intermediate layer in the anode side falls within a range from 0.5 to 1.4 μl/cm 2 /mg.