Patent US5234777A successfully refreshed from Google Patents.
US5234777A
Expired / Lapsed
US
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Membrane catalyst layer for fuel cells
Assignee: Los Alamos National Security LLC
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Filing: 1991-07-29
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Granted: 1993-08-10
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Expires: 2011-07-29
Abstract
Abstract A gas reaction fuel cell incorporates a thin catalyst layer between a solid polymer electrolyte (SPE) membrane and a porous electrode backing. The catalyst layer is preferably less than about 10 μm in thickness with a carbon supported platinum catalyst loading less than about 0.35 mgPt/cm 2 . The film is formed as an ink that is spread and cured on a film release blank. The cured film is then transferred to the SPE membrane and hot pressed into the surface to form a catalyst layer having a controlled thickness and catalyst distribution. Alternatively, the catalyst layer is formed by applying a Na + form of a perfluorosulfonate ionomer directly to the membrane, drying the film at a high temperature, and then converting the film back to the protonated form of the ionomer. The layer has adequate gas permeability so that cell performance is not affected and has a density and particle distribution effective to optimize proton access to the catalyst and electronic continuity for electron flow from the half-cell reaction occurring at the catalyst.
Inventors
- 👤 Mahlon S. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:23
CPC Classifications
H; H01; H01M; H01M4/00; H01M4/86; H01M4/90; H01M4/92; H01M4/925; H01M4/926; H01M8/00; H01M8/10; H01M8/1004; H01M2300/00; H01M2300/0017; H01M2300/0065; H01M2300/0082; Y; Y02; Y02E; Y02E60/00; Y02E60/30; Y02E60/50
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
80 words
A solid polymer electrolyte membrane assembly for separating anodic and cathodic electrode backings in a gas reaction fuel cell, wherein the improvement consists essentially of a solid polymer electrolyte membrane and a composite film of a supported platinum catalyst and a proton conducting ionomer with a thickness less than about 10 μm, said catalyst being uniformly dispersed therein with a platinum loading less than abut 0.35 mgPt/cm 2 , where said film is bonded to said solid polymer electrolyte membrane.
Claim 2
Dependent Claim
80 words
A solid polymer electrolyte membrane assembly for separating anodic and cathodic electrode backings in a gas reaction fuel cell, wherein the improvement consists essentially of a solid polymer electrolyte membrane and a composite film of a supported platinum catalyst and a proton conducting ionomer with a thickness less than about 10 μm, said catalyst being uniformly dispersed therein with a platinum loading less than abut 0.35 mgPt/cm 2 , where said film is bonded to said solid polymer electrolyte membrane.
Claim 3
Dependent Claim
18 words
A membrane assembly according to claim 1, where said platinum loading is greater than 0.1 mg/cm 2 .
Claim 4
Dependent Claim
21 words
A membrane assembly according to claim 1, wherein said proton conducting material is the same material forming said solid polymer electrolyte.
Claim 5
Dependent Claim
52 words
A membrane assembly according to claim 1, wherein said composite film containing proton conducting ionomer is formed from a perfluorosulfonate ionomer by drying a solution containing a Na 30 form of said ionomer at a temperature of at least 150° C. and thereafter converting said N 30 form to a protonated form.
Claim 6
Dependent Claim
43 words
A membrane assembly according to claim 4, wherein said solid polymer electrolyte membrane is formed by converting a membrane of a Na 30 or K 30 form of perfluorosulfonate ionomer to a protonated form with said composite film in said Na + form.
Claim 7
Independent Claim
73 words
A method for fabricating a solid polymer electrolyte membrane assembly for separating anodic and cathodic backings in a gas reaction fuel cell, comprising the steps of: forming a uniform dispersion consisting essentially of a supported Pt catalyst in a perfluorosulfonate ionomer; forming a thin film of said dispersion to a Pt loading less than about 0.35 mg Pt/cm 2 ; and transferring said film to a surface of a solid polymer electrolyte membrane.
Claim 8
Independent Claim
73 words
A method for fabricating a solid polymer electrolyte membrane assembly for separating anodic and cathodic backings in a gas reaction fuel cell, comprising the steps of: forming a uniform dispersion consisting essentially of a supported Pt catalyst in a perfluorosulfonate ionomer; forming a thin film of said dispersion to a Pt loading less than about 0.35 mg Pt/cm 2 ; and transferring said film to a surface of a solid polymer electrolyte membrane.
Claim 9
Dependent Claim
20 words
A method according to claim 6, further including the step of furnishing said perfluorosulfonate ionomer in a Na + form.
Claim 10
Dependent Claim
26 words
A method according to claim 7, further including the step of furnishing said membrane as a perfluorosulfonate material in a Na + or K + form.
Claim 11
Dependent Claim
25 words
A method according to claim 7, further including the step of converting said thin film of said ionomer to a protonated form of said ionomer.
Claim 12
Dependent Claim
61 words
A method according to claim 6, wherein the step of transferring said film comprises the steps of: forming said film over a release blank to a selected catalyst loading; hot pressing said film into said surface of said solid polymer electrolyte membrane to cure said film and adhere said film to said surface; and removing said release blank from said film.
Claim 13
Dependent Claim
42 words
A method according to claim 10, wherein the step of dispersing said catalyst in said ionomer further includes the steps of: adding a solvent to said ionomer and said catalyst to obtain a mixture with a viscosity effective for forming said film;
Claim 14
Independent Claim
121 words
A method for fabricating a solid polymer electrolyte membrane assembly for separating anodic and cathodic electrode backings in a gas reaction fuel cell, comprising the steps of: furnishing a perfluorosulfonate ionomer in a Na + form; forming an ink consisting essentially of a supported Pt catalyst and a solvent uniformly dispersed in said Na + form of said ionomer; forming a film of said ink to a Pt loading less than about 0.35 mg Pt/cm 2 on a surface of a solid polymer electrolyte membrane; heating said film of said ink to a temperature of at least 150° C. for a time effective to dry said ink; and converting said Na + form of said perfluorosulfonate ionomer to a protonated form.
Claim 15
Independent Claim
121 words
A method for fabricating a solid polymer electrolyte membrane assembly for separating anodic and cathodic electrode backings in a gas reaction fuel cell, comprising the steps of: furnishing a perfluorosulfonate ionomer in a Na + form; forming an ink consisting essentially of a supported Pt catalyst and a solvent uniformly dispersed in said Na + form of said ionomer; forming a film of said ink to a Pt loading less than about 0.35 mg Pt/cm 2 on a surface of a solid polymer electrolyte membrane; heating said film of said ink to a temperature of at least 150° C. for a time effective to dry said ink; and converting said Na + form of said perfluorosulfonate ionomer to a protonated form.
Claim 16
Dependent Claim
33 words
A method according to claim 12, wherein the step of furnishing said perfluorosulfonate ionomer in a Na + form includes the step of adding NaOH to a protonated form of said perfluorosulfonate ionomer.
Claim 17
Dependent Claim
22 words
A method according to claim 13, further including the step of furnishing said solid polymer electrolyte membrane in a Na + form.
Claim 18
Dependent Claim
29 words
A method according to claim 12, further including the step of maintaining said membrane planar on a vacuum table while forming said film of said ink on said membrane.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |