Polymer electrolyte membrane, method for producing same, and membrane electrode assembly and polymer electrolyte fuel cell comprising same

A membrane electrode assembly comprising a pair of electrodes, and a polymer electrolyte membrane sandwiched by both electrodes, said polymer electrolyte membrane being obtained by subjecting an ion-conducting, aromatic polymer membrane to a hot-water treatment, said ion-conducting, aromatic polymer membrane having a maximum water absorption in a range of 80-300 weight % based on its dry weight before said hot-water treatment.

A polymer electrolyte fuel cell constituted by stacking a plurality of membrane electrode assemblies via separator plates, each membrane electrode assembly comprising a pair of electrodes and a polymer electrolyte membrane sandwiched by both electrodes, said polymer electrolyte membrane being obtained by subjecting an ion-conducting, aromatic polymer membrane to a hot-water treatment, said ion-conducting, aromatic polymer membrane having a maximum water absorption in a range of 80-300 weight % based on its dry weight before the hot-water treatment.

A composite polymer electrolyte membrane comprising a matrix made of a first sulfonated aromatic polymer having a high ion exchange capacity, and a reinforcing material made of a second sulfonated aromatic polymer having a low ion exchange capacity in the form of fibers or a porous membrane.

A method for producing a composite polymer electrolyte membrane comprising a matrix made of a first sulfonated aromatic polymer having a high ion exchange capacity, and a reinforcing material constituted by a fibrous product made of a second sulfonated aromatic polymer having a low ion exchange capacity, said method comprising using a casting method to form said composite polymer electrolyte membrane, said casting method comprising uniformly dispersing said fibrous product of said second sulfonated aromatic polymer in a solution of said first sulfonated aromatic polymer.

A method for producing a composite polymer electrolyte membrane comprising a matrix made of a first sulfonated aromatic polymer having a high ion exchange capacity, and a reinforcing material constituted by a porous membrane made of a second sulfonated aromatic polymer having a low ion exchange capacity, said method comprising impregnating said porous membrane of said second sulfonated aromatic polymer with a solution of said first sulfonated aromatic polymer.

A polymer electrolyte fuel cell constituted by stacking a plurality of membrane electrode assemblies via separator plates, each membrane electrode assembly comprising a pair of electrodes and a composite polymer electrolyte membrane sandwiched by both electrodes, said composite polymer electrolyte membrane comprising a matrix made of a first sulfonated aromatic polymer having a high ion exchange capacity, and a reinforcing material constituted by a second sulfonated aromatic polymer having a low ion exchange capacity in the form of fibers or a porous membrane.