MEMBRANE/ELECTRODE ASSEMBLY FOR POLYMER ELECTROLYTE FUEL CELLS AND POLYMER ELECTROLYTE FUEL CELL

• US 20090246592A1
• Filed: 03/20/2009
• Published: 10/01/2009
• Est. Priority Date: 03/21/2008
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: KINOSHITA, Shinji
• Granted Patent: US 9,118,043 B2
• Time in Patent Office: Days
• US Class Current: 429/483
• CPC Class Codes: H01M 8/0273 with sealing or supporting means in the form of a frame
• CPC Class Codes: H01M 8/0289 Means for holding the electrolyte solid polymer electrolytes H01M8/1018
• CPC Class Codes: H01M 8/0297 Arrangements for joining electrodes, reservoir layers, heat exchange units or bipolar separators to each other H01M8/0271 takes precedence
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1023 having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• CPC Class Codes: H01M 8/1039 halogenated, e.g. sulfonated polyvinylidene fluorides
• CPC Class Codes: H01M 8/106 characterised by the chemical composition of the porous support
• CPC Class Codes: H01M 8/1062 characterised by the physical properties of the porous support, e.g. its porosity or thickness
• CPC Class Codes: H01M 8/1067 characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

To provide a membrane/electrode assembly for polymer electrolyte fuel cells, which is capable of providing high power generation performance even under a low humidity condition and has sufficient mechanical strength and dimensional stability, and which has an excellent durability even in an environment where moistening and drying are repeated, and a polymer electrolyte fuel cell which is capable of providing high power generation performance even under a low humidity condition.

A membrane/electrode assembly 10 is used, which comprises a cathode 20 having a catalyst layer 22, an anode 30 having a catalyst layer 32, and a polymer electrolyte membrane 40 interposed between the catalyst layer 22 of the cathode 20 and the catalyst layer 32 of the anode 30, wherein at least one of the cathode 20 and the anode 30 further has a reinforcing layer 26 comprising a porous sheet-form reinforcing material made of a polymer, and an electrically conductive fiber.

Claims

1. A membrane/electrode assembly for polymer electrolyte fuel cells, which comprises a cathode having a catalyst layer, an anode having a catalyst layer, and a polymer electrolyte membrane interposed between the catalyst layer of the cathode and the catalyst layer of the anode, wherein at least one of the cathode and the anode further has a reinforcing layer comprising a porous sheet-form reinforcing material made of a polymer, and an electrically conductive fiber.

2. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein each of the cathode and the anode further has a gas diffusion layer, and the reinforcing layer is present between the catalyst layer and the gas diffusion layer.

3. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the reinforcing layer contains a binder, and the binder is a fluorinated ion exchange resin.

4. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 3, wherein the mass ratio of the electrically conductive fiber to the binder (electrically conductive fiber/binder) is from 1/0.05 to 1/1.

5. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the electrically conductive fiber is a carbon fiber, and the carbon fiber has an average fiber diameter of from 50 to 300 nm and an average fiber length of from 5 to 30 μ

m.

6. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the sheet-form reinforcing material has a plurality of pores and has an average pore diameter of from 0.4 to 7 μ

m.

7. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the sheet-form reinforcing material is made of a plurality of fibers, and the fibers have an average fiber diameter of from 0.2 to 7 μ

m.

8. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the sheet-form reinforcing material is a non-woven fabric, and the non-woven fabric is a non-woven fabric made of a polypropylene or a fluoropolymer, produced by a melt-blown method.

9. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the sheet-form reinforcing material is a porous film made of a polytetrafluoroethylene.

10. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, which further has an interlayer in contact with the reinforcing layer.

11. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the polymer electrolyte membrane has a thickness of from 10 to 30 μ

m.

12. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the polymer electrolyte membrane has an equivalent weight of at most 900 g/equivalent.

13. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the polymer electrolyte membrane is a polymer electrolyte membrane made of a polymer (Q) which has repeating units represented by the following formula (U1) and repeating units represented by the formula (U2) and which has an equivalent weight of from 400 to 900 g/equivalent:

14. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, wherein the 90°

peel strength at all interfaces present between the polymer electrolyte membrane and the reinforcing layer is at least 0.5 N/cm.

15. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 1, which further has a frame-form sub-gasket disposed at the periphery of the membrane/electrode assembly for polymer electrolyte fuel cells.

16. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 4, which further has an interlayer in contact with the reinforcing layer.

17. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 4, wherein the polymer electrolyte membrane has a thickness of from 10 to 30 μ

m.

18. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 4, wherein the polymer electrolyte membrane has an equivalent weight of at most 900 g/equivalent.

19. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 4, wherein the polymer electrolyte membrane is a polymer electrolyte membrane made of a polymer (Q) which has repeating units represented by the following formula (U1) and repeating units represented by the formula (U2) and which has an equivalent weight of from 400 to 900 g/equivalent:

20. The membrane/electrode assembly for polymer electrolyte fuel cells according to claim 4, wherein the 90°

peel strength at all interfaces present between the polymer electrolyte membrane and the reinforcing layer is at least 0.5 N/cm.

21. A polymer electrolyte fuel cell having a membrane/electrode assembly for polymer electrolyte fuel is cells, which comprises a cathode having a catalyst layer, an anode having a catalyst layer, and a polymer electrolyte membrane interposed between the catalyst layer of the cathode and the catalyst layer of the anode, wherein at least one of the cathode and the anode further has a reinforcing layer comprising a porous sheet-form reinforcing material made of a polymer, and an electrically conductive fiber;

each of the cathode and the anode further has a gas diffusion layer, and the reinforcing layer is present between the catalyst layer and the gas diffusion layer; and

power generation is carried out by feeding a reaction gas having a relative humidity of at most 25%.

22. The polymer electrolyte fuel cell according to claim 21, wherein the reinforcing layer contains a binder, and the binder is a fluorinated ion exchange resin.

23. The polymer electrolyte fuel cell according to claim 22, wherein the mass ratio of the electrically conductive fiber to the binder (electrically conductive fiber/binder) is from 1/0.05 to 1/1.

24. The polymer electrolyte fuel cell according to claim 21, wherein the electrically conductive fiber is a carbon fiber, and the carbon fiber has an average fiber diameter of from 50 to 300 nm and an average fiber length of from 5 to 30 μ

m.

25. The polymer electrolyte fuel cell according to claim 21, wherein the sheet-form reinforcing material has a plurality of pores and has an average pore diameter of from 0.4 to 7 μ

m.

26. The polymer electrolyte fuel cell according to claim 21, wherein the sheet-form reinforcing material is made of a plurality of fibers, and the fibers have an average fiber diameter of from 0.2 to 7 μ

m.

27. The polymer electrolyte fuel cell according to claim 21, wherein the sheet-form reinforcing material is a non-woven fabric, and the non-woven fabric is a non-woven fabric made of a polypropylene or a fluoropolymer, produced by a melt-blown method.

28. The polymer electrolyte fuel cell according to claim 21, wherein the sheet-form reinforcing material is a porous film made of a polytetrafluoroethylene.

29. The polymer electrolyte fuel cell according to claim 21, which further has an interlayer in contact with the reinforcing layer.

30. The polymer electrolyte fuel cell according to claim 21, wherein the polymer electrolyte membrane has a thickness of from 10 to 30 μ

m.

31. The polymer electrolyte fuel cell according to claim 21, wherein the polymer electrolyte membrane has an equivalent weight of at most 900 g/equivalent.

32. The polymer electrolyte fuel cell according to claim 21, wherein the polymer electrolyte membrane is a polymer electrolyte membrane made of a polymer (Q) which has repeating units represented by the following formula (U1) and repeating units represented by the formula (U2) and which has an equivalent weight of from 400 to 900 g/equivalent:

33. The polymer electrolyte fuel cell according to claim 21, wherein the 90°

peel strength at all interfaces present between the polymer electrolyte membrane and the reinforcing layer is at least 0.5 N/cm.

34. The polymer electrolyte fuel cell according to claim 21, which further has a frame-form sub-gasket disposed at the periphery of the membrane/electrode assembly for polymer electrolyte fuel cells.

reinforcing layer.

35. The polymer electrolyte fuel cell according to claim 23, which further has an interlayer in contact with the reinforcing layer.

36. The polymer electrolyte fuel cell according to claim 23, wherein the polymer electrolyte membrane has a thickness of from 10 to 30 μ

m.

37. The polymer electrolyte fuel cell according to claim 23, wherein the polymer electrolyte membrane has an equivalent weight of at most 900 g/equivalent.

38. The polymer electrolyte fuel cell according to claim 23, wherein the polymer electrolyte membrane is a polymer electrolyte membrane made of a polymer (Q) which has repeating units represented by the following formula (U1) and repeating units represented by the formula (U2) and which has an equivalent weight of from 400 to 900 g/equivalent:

39. The polymer electrolyte fuel cell according to claim 23, wherein the 90°

peel strength at all interfaces present between the polymer electrolyte membrane and the reinforcing layer is at least 0.5 N/cm.