Three layer laminate

• US 4,518,705 A
• Filed: 09/28/1982
• Issued: 05/21/1985
• Est. Priority Date: 10/31/1980
• Status: Expired due to Fees

• Current Assignee: Eltech Systems Corporation (Industrie De Nora S.p.A)
• Original Assignee: Eltech Systems Corporation (Industrie De Nora S.p.A)
• Inventors: Solomon, Frank, Grun, Charles
• Primary Examiner(s): Niebling, John F.
• Application Number:
  US06/425,442
• Time in Patent Office: 966 Days
• Field of Search: 204/291, 204/294, 252/425.3, 252/430, 429/42, 502/101, 156/77, 156/306.6, 156/333
• US Class Current: 502/101
• CPC Class Codes: C25B 11/04 characterised by the material
• CPC Class Codes: C25B 11/043 Carbon, e.g. diamond or graphene
• CPC Class Codes: H01M 4/8663 Selection of inactive substances as ingredients for catalytic active masses, e.g. binders, fillers
• CPC Class Codes: H01M 4/8821 Wet proofing
• CPC Class Codes: H01M 4/96 Carbon-based electrodes
• CPC Class Codes: H01M 8/0234 Carbonaceous material
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The disclosure is directed to preparing three-layer laminated electrodes suitable for use as oxygen (air) cathodes in chlor-alkali and other electrochemical cells, fuel cells and in other electrochemical applications.

This three-layer laminate includes an active layer or sheet containing from about 60 to about 85 wt. % active carbon, the remainder being unsintered, fibrillated polytetrafluoroethylene in intimate admixture with said active carbon, said active layer laminated on its working surface to a current distributor and on its opposite surface to a porous, coherent, hydrophobic polytetrafluoroethylene-containing wetproofing layer.

Claims

1. A process for forming an electrode comprising adding a dilute aqueous dispersion of polytetrafluoroethylene particles to an aqueous suspension of larger active carbon particles to discontinuously coat said active carbon particles with smaller polytetrafluoroethylene particles;

shear blending said discontinuously coated particles to form an intimate mix of active carbon particles and attenuated and fibrillated polytetrafluoroethylene;

comminuting said intimate mix to yield a granular mix;

forming said granular mix into an active sheet; and

laminating the working surface of said active sheet to a current distributor and the opposite surface thereof to a polytetrafluoroethylene-containing wetproofing layer.

2. A process as in claim 1 wherein said granular mix is formed into a sheet by rolling it at temperatures of from about 60°

to 90°

C.

3. A process as in claim 1 wherein said active carbon particles have a particle size ranging from about 1 to 30 microns.

4. A process as in claim 1 wherein a pore-forming agent is added to said discontinuously coated active carbon particles and blended therewith prior to said shear blending.

5. A process as in claim 1 wherein said intimate mix is chopped to yield said granular mix.

6. A process as in claim 1 wherein said granular mix contains from about 60 to 85 wt.% active carbon particles, the remainder being polytetrafluoroethylene.

7. A process as in claim 1 wherein said active carbon particles have an ash content of less than about 4 wt.% and a B.E.T. surface area of about 1000 m² /g and higher.

8. A process as in claim 1 which includes depositing a precious metal catalyst on said active carbon particles before adding said dilute polytetrafluoroethylene dispersion thereto.

9. A process as in claim 8 wherein said precious metal is platinum.

10. A process as in claim 8 wherein said precious metal is silver.