Polymer electrolyte membrane, method of manufacturing the same and fuel cell including the polymer electrolyte membrane

Abstract

A polymer electrolyte membrane, a method of manufacturing the same, and a fuel cell including the polymer electrolyte membrane are provided, wherein the polymer electrolyte forms an interpenetrating polymer network (IPN) of a polymer by simple blending of a hydrophobic polyimide having a reactive terminal group and a hydrophilic aromatic polymer having ion conductivity. The polymer electrolyte membrane has reduced swelling properties due to highly dense crosslinking of polyimide through the reactive terminal group, shows high ion conductivity at low humidity, and has methanol crossover suppressing ability. Accordingly, a fuel cell with improved electric and mechanical properties can be provided.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawing in which:

FIG. 1 is a schematic drawing of a membrane electrode assembly according to an embodiment of the present invention.

Claims

1. A polymer electrolyte membrane comprising: polyimide having a reactive terminal group; andan ion conductive polymer.

2. The polymer electrolyte membrane of claim 1, wherein the polyimide is a compound having a repeating unit represented by Formula 1 below.

3. The polymer electrolyte membrane of claim 1, wherein X and X′ are each independently selected from the group consisting of

4. The polymer electrolyte membrane of claim 1, wherein Y and Y′ are each independently selected from the group consisting of

5. The polymer electrolyte membrane of claim 2, wherein E is derived from at least one compound independently selected from the group consisting of 5-norbornene-2,3-dicarboxylic anhydride (NDA), 3,4,5,6-tetrahydrophthalic anhydride, cis-1,2,3,6-tetrahydrophthalic anhydride, maleic anhydride (MA), 2,3-dimethylmaleic anhydride (DMMA), citraconic anhydride (CA), itaconic anhydride (IA), maleic imide, and ethynyl aniline (EA).

6. The polymer electrolyte membrane of claim 1, wherein the ion conductive polymer is an aromatic polymer having an ionic group.

7. The polymer electrolyte membrane of claim 1, wherein the ion conductive polymer is at least one selected from the group consisting of sulfonated poly(arylene ether sulfone), sulfonated poly(arylene ether ketone), sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, perfluorated polymer, polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoro propylene, copolymers including at least one monomer constituting the above polymers, and combinations thereof.

8. The polymer electrolyte membrane of claim 1, wherein the content of the polyimide is in the range of 20 to 400 parts by weight based on 100 parts by weight of the ion conductive polymer.

9. The polymer electrolyte membrane of claim 1, further comprising a solid acid.

10. The polymer electrolyte membrane of claim 9, wherein the solid acid is one of compounds represented by Formulae 4 through 6 below.

11. A method of preparing a polymer electrolyte membrane, the method comprising: providing a composition adapted to form a polymer electrolyte membrane, comprising a polyamic acid having a reactive terminal group, an ion conductive polymer, and a solvent;coating the composition to a substrate; andheat-treating the coated substrate.

12. The method of claim 11, wherein the polyamic acid is a compound comprising a repeating unit represented by Formula 7 below.

13. The method of claim 11, wherein the reactive terminal group is at least one selected from the group consisting of

14. The method of claim 11, wherein the polyamic acid is synthesized by reacting a tetracarboxyl acid dianhydride compound represented by at least one of Formulae 8 and 9 below; a diamine compound represented by at least one of Formulae 10 and 11 below; and a monoamine compound or monoanhydride compound having at least one carbon-carbon double bond to a polar solvent:

15. The method of claim 14, wherein the dianhydride compound is at least one selected from the group consisting of pyromellitic dianhydride, 3,3,4,4-biphenyl tetracarboxylic dianhydride, 4,4-oxydiphthalic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 2,2-bis(3,4-benzenedicarboxylic anhydride)perfluoropropane, and 4,4-sulfonyldiphthalic dianhydride.

16. The method of claim 14, wherein the diamine compound is at least one selected from the group consisting of 1,3-diamino-4-dihydroxybenzene, 1,3-diamino-5-dihydroxybenzene, 3,3′-diamino-4,4′-dihydroxybiphenyl, 4,4′-diamino-3,3′-dihydroxybiphenyl, 2,2-bis(3-amino-4-hydroxyphenyl)propane, bis(4-amino-3-hydroxyphenyl) propane, bis(3-amino-4-hydroxyphenyl)sulfone, bis(4-amino-3-hydroxyphenyl)sulfone, bis(3-amino-4-hydroxyphenyl)ether, bis(4-amino-3-hydroxyphenyl)ether, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.

17. The method of claim 14, wherein the content of the monoamine compound or the monoanhydride compound is in the range of 0.05 to 0.5 mol with respect to 1 mol of the diamine compound.

18. The method of claim 11, wherein the solvent in the composition for forming the polymer electrolyte membrane is at least one selected from the group consisting of N-methyl-2-pyrrolidone, dimethylformamide, methylsulfoxide, dimethylsulfoxide, and N,N′-dimethyl acetamide.

19. The method of claim 11, wherein the content of the polyamic acid is in the range of 20 to 400 parts by weight to 100 parts by weight of the ion conductive polymer.

20. A fuel cell comprising: a cathode;an anode; anda polymer electrolyte membrane interposed between the cathode and the anode,wherein the polymer electrolyte membrane is a polymer electrolyte membrane of claim 1.

21. The fuel cell of claim 20, wherein the cathode has a platinum-supported carbon catalyst, and the anode has a platinum/ruthenium-supported carbon catalyst.