Composite electrolyte for fuel cells

• US 6,630,265 B1
• Filed: 08/13/2002
• Issued: 10/07/2003
• Est. Priority Date: 08/13/2002
• Status: Expired due to Fees

• Current Assignee: Hoku Corp.
• Original Assignee: Hoku Scientific, Inc.
• Inventors: Taft, Karl Milton III, Kurano, Matthew Robert
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US10/219,083
• Time in Patent Office: 420 Days
• Field of Search: 204/296, 429/30, 429/33, 429/34, 429/39, 429/46, 429/302, 429/303, 429/249, 429/251, 429/252, 429/253, 429/254, 524/445, 427/115
• US Class Current: 429/491
• CPC Class Codes: B01D 67/0079 Manufacture of membranes comprising organic and inorganic components
• CPC Class Codes: B01D 67/00793 Dispersing a component, e.g. as particles or powder, in another component
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: B01D 69/14111 with nanoscale dispersed material, e.g. nanoparticles
• CPC Class Codes: B01D 71/024 Oxides
• CPC Class Codes: B01D 71/027 Silicium oxide
• CPC Class Codes: B01D 71/028 Molecular sieves carbon B01D71/021
• CPC Class Codes: B01D 71/0281 Zeolites
• CPC Class Codes: B01D 71/52 Polyethers
• CPC Class Codes: B01D 71/5222 Polyetherketone, polyetheretherketone, or polyaryletherketone
• CPC Class Codes: C08J 2383/02 Polysilicates
• CPC Class Codes: C08J 5/22 Films, membranes or diaphragms
• CPC Class Codes: C08K 3/346 Clay
• CPC Class Codes: H01B 1/122 Ionic conductors
• CPC Class Codes: H01M 2300/0068 inorganic
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 2300/0091 in the form of mixtures
• CPC Class Codes: H01M 8/0289 Means for holding the electrolyte solid polymer electrolytes H01M8/1018
• CPC Class Codes: H01M 8/1007 with both reactants being gaseous or vaporised H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1016 characterised by the electrolyte material H01M8/12 takes precedence
• CPC Class Codes: Y02E 60/50 : Fuel cells

Abstract

An inexpensive composite electrolyte for use in electrochemical fuel cells includes (i) an inorganic cation exchange material, (i) a silica-based binder; and (ii) a polymer-based binder. The cation exchange material includes aluminosilicate clays. The composite electrolyte can be fabricated with a tape casting apparatus.

Claims

1. A composite electrolyte for use in electrochemical fuel cells that comprises:

(i) an inorganic cation exchange material;

(ii) a silica-based binder; and

(iii) a polymer-based binder.

2. The composite electrolyte of claim 1 wherein the inorganic cation exchange material comprises about 10 wt % to about 99 wt %, the silica-based binder comprises about 0.5 wt % to about 40 wt %, and the polymer-based binder comprises about 1 wt % to 90 wt % of the composite electrolyte.

3. The composite electrolyte of claim 1 wherein the inorganic cation exchange material comprises about 75 wt % to about 85 wt %, the silica-based binder comprises about 2.5 wt % to about 7.5 wt %, and the polymer-based binder comprises about 15 wt % to 40 wt % of the composite electrolyte.

4. The composite electrolyte of claim 1 wherein the silica-based binder is selected from the group consisting of colloidal silica, tetraethylorthsilicate (TEOS) and mixtures thereof.

5. The composite electrolyte of claim 1 wherein the inorganic cation exchange material is selected from the group consisting of clays, zeolites, hydrous oxides, inorganic salts, and mixtures thereof.

6. The composite electrolyte of claim 1 wherein the inorganic cation exchange material is selected from the group consisting of montmorillonite, kaolinite, vermiculite, smectite, hectorite, mica, bentonite, nontronite, beidellite, volkonskoite, saponite, magadite, kenyaite, zeolite, alumina, rutile, and mixtures thereof.

7. The composite electrolyte of claim 1 wherein the polymer-based binder is selected from the group consisting of latex, thermoplastic, and mixtures thereof.

8. The composite electrolyte of claim 1 wherein the inorganic cation exchange material, the silica-based binder and the polymer-based binder comprises 97 wt % or more of solids content of the composite electrolyte.

9. The composite electrolyte of claim 1 wherein the composite electrolyte when measured in the substantially dried state consists essentially of the inorganic cation exchange material, the silica-based binder and the polymer-based binder.

10. The composite electrolyte of claim 1 wherein the composite electrolyte has a proton conductivity of about 0.05 S/cm or higher.

11. An electrochemical fuel cell comprising:

(i) an anode;

(ii) a cathode;

(iii) fuel supply means for supplying fuel toward the anode;

(iv) an oxidant supply means for supplying oxidant toward the cathode; and

(v) a composite electrolyte that is positioned between the anode and cathode, wherein the composite electrolyte comprises (a) an inorganic cation exchange material, (b) a silica-based binder, and (c) a polymer-based binder.

12. The fuel cell of claim 11 wherein the inorganic cation exchange material comprises about 75 wt % to about 85 wt %, the silica-based binder comprises about 2.5 wt % to about 7.5 wt %, and the polymer-based binder comprises about 15 wt % to 40 wt % of the composite electrolyte.

13. The fuel cell of claim 11 wherein the inorganic cation exchange material comprises about 75 wt % to about 85 wt %, the silica-based binder comprises about 2.5 wt % to about 7.5 wt %, and the polymer-based binder comprises about 15 wt % to 40 wt % of the composite electrolyte.

14. The fuel cell of claim 11 wherein the inorganic cation exchange material is selected from the group consisting of clays, zeolites, hydrous oxides, inorganic salts and mixtures thereof.

15. The fuel cell of claim 11 wherein the inorganic cation exchange material is selected from the group consisting of montmorillonite, kaolinite, vermiculite, smectite, hectorite, mica, bentonite, nontronite, beidellite, volkonskoite, saponite, magadite, kenyaite, zeolite, alumina, rutile, and mixtures thereof.

16. The fuel cell of claim 11 wherein the silica-based binder is selected from the group consisting of colloidal silica, tetraethylorthsilicate (TEOS) and mixtures thereof.

17. The fuel cell of claim 11 wherein the polymer-based binder is selected from the group consisting of latex, thermoplastic, and mixtures thereof.

18. The fuel cell of claim 11 wherein the inorganic cation exchange material, the silicabased binder and the polymer-based binder comprises 97 wt % or more of solids content of the composite electrolyte.

19. The fuel cell of claim 11 wherein the composite electrolyte when measured in the substantially dried state consists essentially of the inorganic cation exchange material, the silica-based binder and the polymer-based binder.

20. The fuel cell of claim 11 wherein the composite electrolyte has a proton conductivity of about 0.05 S/cm or higher.

21. A method of fabricating a composite electrolyte for use in an electrochemical fuel cell that comprises the steps of:

(i) applying a viscous liquid composition comprising of (a) an inorganic cation exchange material, (b) a silica-based binder, (c) a polymer-based binder, and (d) a solvent onto a surface of a substrate;

(ii) spreading the viscous liquid composition to form a uniform thickness layer on the substrate; and

(iii) allowing the solvent to evaporate from the viscous liquid composition to yield the composite electrolyte.

22. The method of claim 21 wherein step (ii) comprises drawing the viscous liquid composition through a doctor blade assembly.

23. The method of claim 21 further comprising heating the viscous liquid composition in step (iii).

24. The method of claim 21 wherein the inorganic cation exchange material comprises about 10 wt % to about 99 wt %, the silica-based binder comprises about 0.5 wt % to about 40 wt %, and the polymer-based binder comprises about 1 wt % to 90 wt % of the composite electrolyte.

25. The method of claim 21 wherein the inorganic cation exchange material comprises about 75 wt % to about 85 wt %, the silica-based binder comprises about 2.5 wt % to about 7.5 wt %, and the polymer-based binder comprises about 15 wt % to 40 wt % of the composite electrolyte.

26. The method of claim 21 wherein the inorganic cation exchange material is selected from the group consisting of clays, zeolites, hydrous oxides, inorganic salts, and mixtures thereof.

27. The method of claim 21 wherein the cation exchange material is selected from the group consisting of montmorillonite, kaolinite, vermiculite, smectite, hectorite, mica, bentonite, nontronite, beidellite, volkonskoite, saponite, magadite, kenyaite, zeolite, alumina, rutile, and mixtures thereof.

28. The method of claim 21 wherein the silica-based binder is selected from the group consisting of colloidal silica, tetraethylorthsilicate (TEOS) and mixtures thereof.

29. The method of claim 21 wherein the polymer-based binder is selected from the group consisting of latex, thermoplastic, and mixtures thereof.

30. The method of claim 21 wherein the solvent comprises water.

31. The method of claim 21 wherein the inorganic cation exchange material, the silicabased binder and the polymer-based binder comprises 97 wt % or more of solids content of the composite electrolyte.

32. The method of claim 21 wherein the composite electrolyte when measured in the substantially dried state consists essentially of the inorganic cation exchange material, the silica-based binder and the polymer-based binder.

33. The method of claim 21 wherein the composite electrolyte has a proton conductivity of about 0.05 S/cm or higher.