COMPOSITE POLYMER ELECTROLYTE MEMBRANE, AS WELL AS ELECTROLYTE MEMBRANE HAVING CATALYST LAYER, MEMBRANE ELECTRODE ASSEMBLY, AND SOLID POLYMER FUEL CELL IN WHICH SAID COMPOSITE POLYMER ELECTROLYTE MEMBRANE IS USED

摘要

The present invention addresses the problem of providing: a polymer electrolyte fuel membrane having exceptional proton conductivity even under low-humidification conditions and low-temperature conditions, having exceptional mechanical strength and physical durability, and enabling a high energy density and long-term durability to be achieved when made into a solid polymer fuel cell; as well as a membrane electrode assembly and a solid polymer fuel cell in which the polymer electrolyte fuel membrane is used. The present invention is a composite polymer electrolyte membrane having a composite layer obtained by compounding an aromatic hydrocarbon-based polymer electrolyte and a fluoropolymer porous membrane, wherein: the ratio of the atomic composition percentage O (at%) of oxygen in relation to the atomic composition percentage F (at%) of fluorine, in the outermost surface of the fluoropolymer porous membrane, as measured by X-ray photoelectron spectroscopy (XPS) (ie., the O/F ratio) is 0.2 to 2.0; and the aromatic hydrocarbon-based polymer electrolyte in the composite layer forms a phase separation structure.