Abstract: A membrane-electrode unit includes two diffusion layers, each layer being in contact with a catalyst layer and the layers separated by a polymer electrolyte membrane. A polymer frame contacts at least one of the two surfaces of the membrane. The frame includes an inner region on at least one surface of the membrane and an outer region outside the diffusion layer. The thickness of the outer region is between 50 and 100% of the thickness of the inner region. The thickness of the outer region is reduced by a maximum 2% at a temperature of 80° C. and a pressure of 10 N/mm over a period of 5 hours, the reduction being determined after a first compression process, carried out at a pressure of 10 N/mm for 1 minute.

Abstract: The invention relates to a membrane-electrode unit comprising two gas diffusion layers, each layer being in contact with a catalyst layer and said gas diffusion layers being separated by a polymer electrolyte membrane. A polymer frame is provided on at least one of the two surfaces of the polymer electrolyte membrane that are in contact with the catalyst layer. Said polymer frame comprises an inner region that lies on at least one surface of the polymer electrolyte membrane and an outer region that lies outside the gas diffusion layer. The thickness of all components of the outer region is between 50 and 100% of the thickness of all components of the inner region. The thickness of the outer region is reduced by a maximum 2% at a temperature of 80° C. and a pressure of 10 N/mm2 over a period of 5 hours, said reduction in thickness being determined after a first compression process, which is carried out at a pressure of 10 N/mm2 for 1 minute.