Method for producing a catalyst-coated membrane

A method for producing a membrane for a fuel or electrolytic cell, comprising:

• (i) applying a liquid coating composition containing a supported precious metal-containing catalyst and an ionomer both to a front side and a back side of a polymer electrolyte membrane containing an ionomer, or a first liquid coating composition containing a supported precious metal-containing catalyst and an ionomer is applied only on a front side of a polymer electrolyte membrane containing an ionomer, and a second liquid coating composition containing a supported precious metal-containing catalyst and an ionomer is applied on a back side of the polymer electrolyte membrane, wherein the first and second liquid coating compositions are different, so that a coated polymer electrolyte membrane with a catalyst-containing layer on its front and back side is obtained, wherein the ionomer of the liquid coating composition and the ionomer of the polymer electrolyte membrane are each a copolymer which, as monomers, contain a fluoroethylene and a fluorovinyl ether containing a sulfonic acid group, wherein the fluorovinyl ether containing a sulfonic acid group has the formula (I):
• —CF(OR)—CF2— (I)
• wherein
• R has the following formula (II):
• —(CF2—CF(CF3)—O)x(CF2)y—SO3H (II)
• where x=0-3 and y=1-5, and
• (ii) thermally treating the coated polymer electrolyte membrane by heating it to a temperature in a range of 178° C. to 250° C. without exposure to external pressure.