Patent ID: 8614028

Claim:
A membrane and electrode assembly comprising a pair of catalyst layers and a polymer electrolyte membrane situated between the pair of catalyst layer, each catalyst layer of the pair of catalyst layers comprising at least two kinds of catalyst layers, said two kinds of catalyst layers being a first kind of catalyst layer and a second kind of catalyst layer, wherein the first kind of catalyst layer and the second kind of catalyst layer each comprises a polymer electrolyte and a plurality of particles carrying a catalyst material, a proportion of the polymer electrolyte expressed by formula 1 in the each catalyst layer of the pair of catalyst layers is decreased toward the polymer electrolyte membrane (the inside) from a surface of the each catalyst layer of the pair of catalyst layers(the outside), the proportion of the polymer electrolyte expressed by formula 1 in the first kind of catalyst layer is a first proportion, the proportion of the polymer electrolyte expressed by formula 1 in the second kind of catalyst layer is a second proportion, the second proportion is within a range of from 1.2 times to 5.0 times both inclusive of the first proportion, and a thickness of the first kind of catalyst layer is greater than a thickness of the second kind of catalyst layer, (Proportion of polymer electrolyte)={(mass of polymer electrolyte)/(mass of particles in the particles carrying catalyst material)} Formula 1