Patent ID: 8475971

Claim:
A method of enhancing electrical performance of a polymer electrolyte membrane for a fuel cell, comprising: providing a preformed perfluorosulfonic acid membrane having a first dry weight and having a first acid number that defines an equivalent weight of sulfonic acid groups in said perfluorosulfonic acid membrane; providing an aqueous solution comprising a perfluorosulfonic acid ionomer dispersed or dissolved in an aqueous hydroxylated-hydrocarbon, said perfluorosulfonic acid ionomer having a second acid number that defines an equivalent weight of sulfonic acid groups in said perfluorosulfonic acid ionomer, said second acid number of said perfluorosulfonic acid ionomer being at least as high as said first acid number of said perfluorosulfonic acid membrane; immersing said preformed perfluorosulfonic acid membrane having said first dry weight in said aqueous solution so that said perfluorosulfonic acid ionomer dispersed or dissolved in said aqueous hydroxylated-hydrocarbon diffuses into said perfluorosulfonic acid membrane, said preformed perfluorosulfonic acid membrane swelling during said immersion; removing said perfluorosulfonic acid membrane from said aqueous solution; and drying said perfluorosulfonic acid membrane under tension to provide an enhanced perfluorosulfonic acid membrane comprising a second dry weight higher than said first dry weight and that is thinner than said preformed perfluorosulfonic acid membrane.