Coating Slurry for Cation-Conducting Polymer Composite Membrane, Method for Producing Cation-Conducting Polymer Composite Membrane Using the Coating Slurry, Membrane-Electrode Assembly, and Fuel Cell

• US 20080182154A1
• Filed: 01/18/2008
• Published: 07/31/2008
• Est. Priority Date: 01/30/2007
• Status: Abandoned Application

• Current Assignee: Cheil Industries Incorporated (Samsung Group)
• Original Assignee: Cheil Industries Incorporated (Samsung Group)
• Inventors: KIM, Tae Kyoung, CHOI, Yeong Suk, KIM, Hae Kyoung, KANG, Myeong Soon, LEE, Won Mok
• Application Number:
  US12/016,409
• Publication Number:
  US 20080182154A1
• Time in Patent Office: Days
• US Class Current: 429/42
• CPC Class Codes: C09D 5/24 Electrically-conducting paints conductive materials H01B1/00
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 2300/0094 in the form of layered products, e.g. coatings
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1011 Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Disclosed herein is a slurry-type coating solution for cation-conducting polymer composite membranes that is capable of producing cation-conducting polymer composite membranes with high ionic conductivity as well as low methanol permeability and low ohmic resistance when used in direct-methanol fuel cells, via pluralization of solvents and use of specific additives. The coating slurry comprises about 1 to about 10 parts by weight of a sulfonated clay, about 100 parts by weight of a cation exchange group-containing polymer, and a co-solvent consisting of a high-boiling point solvent with a boiling point of about 180 to about 250° C. and a low-boiling point solvent with a boiling point of about 100 to about 180° C.

Claims

1. A coating slurry for a cation-conducting polymer composite membrane comprising:

about 1 to about 10 parts by weight of a sulfonated clay;

about 100 parts by weight of a cation exchange group-containing polymer; and

a co-solvent comprising a high-boiling point solvent with a boiling point of about 180 to about 250°

C. and a low-boiling point solvent with a boiling point of about 100 to about 180°

C.

2. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the high-boiling point solvent and the low-boiling point solvent are used in a weight ratio of about 1:

20 to about 1;

1.5.

3. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the coating slurry has a viscosity of about 1,000 to about 5,000 cps.

4. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the cation exchange group-containing polymer is selected from fluorine-based polymers comprising at least one side chain comprising at least one cation exchange group, hydrocarbon-based polymers comprising at least one side chain comprising at least one cation exchange group, and mixtures thereof.

5. The coating slurry for a cation-conducting polymer composite membrane according to claim 4, wherein the hydrocarbon-based polymer comprising at least one side chain comprising at least one cation exchange group is selected from polysulfone-based polymers, polyaryl ether sulfone-based polymers, polyphosphazene-based polymers, polyether ketone-based polymers, polyaryl ether ketone-based polymers, poly(phthalazinone ether ketone)-based polymers, polyimide-based polymers, polybenzimidazole-based polymers, acrylonitrile-butadiene-styrene (ABS)-based polymers, styrene-butadiene rubber (SBR)-based polymers, polystyrene-based polymers, polyolefin-based polymers, polycarbonate-based polymers, poly ethylene terephthalate (PET)-based polymers, poly ethylene naphthalate (PEN)-based polymers, acryl-based polymers and mixtures thereof.

6. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the cation exchange group is at least one selected from a sulfonic acid group, a phosphonic acid group, a sulfuric acid group, a phosphoric acid group, a carboxylic acid group and a sulfonimide group.

7. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the sulfonated clay comprises a sulfonic acid and comprises at least one clay selected from montmorillonite (MMT), illite, kaolinite, vermiculite, smectite, hectorite, mica, bentonite, nontronite, saponite, zeolite, alumina, rutile, talc, and mixtures thereof.

8. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the high-boiling point solvent comprises at least one solvent selected from N-methyl-2-pyrrolidinone (NMP), dimethyl sulfoxide (DMSO), ethylene glycol (EG), and mixtures thereof.

9. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, wherein the low-boiling point solvent comprises at least one solvent selected from N,N-dimethyl acetamide (DMAc), dimethylformamide (DMF), cyclopentanone, H₂O, and mixtures thereof.

10. The coating slurry for a cation-conducting polymer composite membrane according to claim 1, comprising a fluorine-based polymer comprising at least one side chain comprising at least one cation exchange group, sulfonated montmorillonite, and a co-solvent comprising NMP as a high-boiling point solvent and DMAc as a low-boiling point solvent.

11. A method for producing a cation-conducting polymer composite membrane comprising:

coating a coating slurry comprising about 1 to about 10 parts by weight of a sulfonated clay;

about 100 parts by weight of a cation exchange group-containing polymer; and

a co-solvent comprising a high-boiling point solvent with a boiling point of about 180 to about 250°

C. and a low-boiling point solvent with a boiling point of about 100 to about 180°

C. on one side of a polymer film to form a coating film;

subjecting the coating film to primary-drying to primarily remove the low-boiling point solvent in the coating film; and

subjecting the coating film to secondary-drying to primarily remove the high-boiling point solvent in the coating film.

12. The method according to claim 11, wherein the coating step comprises doctor blade tape casting.

13. The method according to claim 11, wherein the polymer film is selected from poly(ethylene terephthalate) (PET)-based films, poly(ethylene naphthalate)(PEN)-based films, polycarbonate (PC)-based films, teflon-based films, polyimide-based films, polyolefin-based films, and films surface-treated with a release material.

14. The method according to claim 11, wherein the coating film has a thickness of about 10 μ

m to about 3 mm.

15. The method according to claim 11, wherein the coating film is produced with a coater selected from a die coater, comma coater, a blade coater and a gravure coater.

16. The method according to claim 11, further comprising:

rolling the coating film, after secondary-drying,

wherein the overall process is carried out under the conditions that a length (m) of drying equipment/a line run rate (m/min) of the polymer film is about 2 to about 20.

18. A membrane-electrode assembly comprising:

a cation-conducting polymer composite membrane produced by the method according to claim 11;

catalyst layers each deposition-coated onto both sides of the cation-conducting polymer composite membrane; and

gas diffusion layers each arranged on the catalyst layers.

19. A fuel cell comprising:

a membrane-electrode assembly according to claim 18; and

a pair of bipolar plates each arranged on both sides of the membrane-electrode assembly.

17. A cation-conducting polymer composite membrane comprising:

a film comprising sulfonated clay and a cation exchange group-containing polymer; and

a polymer film,

wherein the cation-conducting polymer composite membrane has an ionic conductivity of about 0.092 S/cm or higher and a methanol permeability of about 1.25 cm²/sec or lower.