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US 8,475,971 B2Granted
Membrane treatment method
AssigneeGM Global Technology Operations LLC
InventorsTimothy J. Fuller, Beba T. Dobulis
Life of this patent
Estimating the term…
Abstract
A method of enhancing electrical performance of a membrane for a fuel cell is disclosed. The method includes providing a perfluorosulfonic acid (PFSA) ionomer in an aqueous hydroxylated hydrocarbon aqueous solution. The PFSA dispersion or solution has an acid number the same or higher than an acid number of the membrane. The membrane is immersed in the solution such that the high acid number PFSA dispersion diffuses into the membrane. After immersion, the removed membrane is then dried under tension.
Claims19
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.
3 more elements
A method of enhancing electrical performance of a polymer electrolyte membrane for a fuel cell, comprising:
- providing a preformed perfluorosulfonic acid membrane having a dry weight and having a first acid number that defines an equivalent weight of sulfonic acid groups in said perfluorosulfonic acid membrane;
- imbibing from about 5 to about 50 weight percent of a perfluorosulfonic acid ionomer having said dry weight into said preformed perfluorosulfonic acid membrane, wherein said weight percent is calculated on the basis of the dry weight increase of said preformed perfluorosulfonic acid membrane, said perfluorosulfonic acid ionomer having a second acid number that defines an equivalent weight of sulfonic acid groups in said perfluorosulfonic acid ionomer, and said second acid number of said perfluorosulfonic acid ionomer being higher than said first acid number of said perfluorosulfonic acid membrane;
- and
- drying said perfluorosulfonic acid membrane under tension to provide an enhanced perfluorosulfonic acid membrane that is thinner than said preformed perfluorosulfonic acid membrane.
1 more element
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 one half the thickness of said preformed perfluorosulfonic acid membrane.
3 more elements
A method of enhancing electrical performance of a polymer electrolyte membrane for a fuel cell, comprising:
- providing a preformed perfluorosulfonic acid membrane having a dry weight and having a first acid number that defines an equivalent weight of sulfonic acid groups in said perfluorosulfonic acid membrane;
- imbibing from about 5 to about 50 weight percent of a perfluorosulfonic acid ionomer having said dry weight into said preformed perfluorosulfonic acid membrane, wherein said weight percent is calculated on the basis of the dry weight increase of said preformed perfluorosulfonic acid membrane, said perfluorosulfonic acid ionomer having a second acid number that defines an equivalent weight of sulfonic acid groups in said perfluorosulfonic acid ionomer, and said second acid number of said perfluorosulfonic acid ionomer being higher than said first acid number of said perfluorosulfonic acid membrane;
- and
- drying said perfluorosulfonic acid membrane under tension to provide an enhanced perfluorosulfonic acid membrane that is one half the thickness of said preformed perfluorosulfonic acid membrane.
1 more element
Dependencies are inferred from the claim text.