| 主权项 |
1. A membrane electrode assembly comprising:
two electrochemically active electrodes separated by a polymer electrolyte membrane having a surface and an opposite surface, wherein the polymer electrolyte membrane comprises a polymer with repeating units of polyazole and a dopant including phosphoric acid, wherein the dopant is present with a degree of doping, indicated in moles of the phosphoric acid per mole of repeating unit of the polyazole, of 5 to 50, a polyimide layer on the surface and in contact with one of the two electrodes, and a polyimide layer on the opposite surface and in contact with the other of the two electrodes, and wherein each of said polyimide layers on the polymer electrolyte membrane form a frame structure, in which each of the two polyimide layers extend beyond the membrane and are in flat contact with one another and welded together, and the frame overlaps each of the two electrodes by 0.2 to 5 mm, but the frame does not cover a free electrode area, and the membrane electrode assembly can be operated at temperatures above 120° C. without moistening, wherein the thickness of the polyimide layers is in the range from 5 μm to 1000 μm, and at least one of the polyimide layers is coated with fluoropolymer facing the electrode to improve upon the adhesion between the polyimide layer and the electrode, and the fluoropolymer coating has a thickness of at least 0.5 μm. |
