# US 2013/0157167 A1 · Alternate material for electrode topcoat

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- Number: US 2013/0157167 A1
- Document ID: US20130157167A1
- Status: Published application
- Kind: A1
- Application number: 13/331,074
- Filed: 2011-12-20
- Published: 2013-06-20
- Earliest claimed: 2011-12-20
- Assignees: GM Global Technology Operations LLC
- Inventors: Scott L. Peters; Amit Nayar; Ruichun Jiang
- Web page: https://patentgrep.com/patent/US20130157167A1

## CPC

- H01M 4/8657: {layered}
- H01M 4/8668: {Binders}
- H01M 2008/1095: {Fuel cells with polymeric electrolytes}
- Y02E 60/50: Fuel cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A reduced gas crossover fuel cell membrane and method of making. The fuel cell member includes an electrode layer with a catalyst and an electrochemically-active first ionomer and an overcoat layer disposed on the electrode layer. The overcoat layer is made of the same or different second ionomer relative to the first ionomer of the electrode layer with at least one reduced gas crossover characteristic.

## Claims

### Claim 1

A fuel cell electrode comprising:
a proton-conductive substrate;
an electrode layer coupled to said substrate, said electrode layer comprising a catalyst and an electrochemically-active first ionomer; and
an overcoat layer disposed on said electrode layer, said overcoat layer comprising a second ionomer with at least one reduced gas crossover characteristic relative to said first ionomer.

### Claim 2 (depends on 1)

The fuel cell electrode of claim 1, wherein said first ionomer comprises perfluorosulfonic acid and said second ionomer comprises perfluorocyclobutane.

### Claim 3 (depends on 1)

The fuel cell electrode of claim 1, wherein said second ionomer comprises perfluorocyclobutane.

### Claim 4 (depends on 3)

The fuel cell electrode of claim 3, wherein said second ionomer further comprises polyvinylidene fluoride.

### Claim 5 (depends on 1)

The fuel cell electrode of claim 1, wherein said second ionomer comprises sulfonated polyether ether ketone.

### Claim 6 (depends on 1)

The fuel cell electrode of claim 1, wherein said second ionomer comprises sulfonated poly p-phenylene.

### Claim 7 (depends on 1)

The fuel cell electrode of claim 1, wherein said proton-conductive substrate comprises a proton-conductive membrane.

### Claim 8 (depends on 1)

The fuel cell electrode of claim 1, wherein said first ionomer and said second ionomer comprises the same material.

### Claim 9

A membrane electrode assembly comprising:
a proton-conductive membrane; and
a plurality of electrodes coupled to said membrane, each of said plurality of electrodes comprising:
an electrode layer comprising a catalyst and an electrochemically-active first ionomer; and
an overcoat layer disposed on said electrode layer, said overcoat layer comprising a second ionomer with at least one reduced gas crossover characteristic relative to said first ionomer.

### Claim 10 (depends on 9)

The membrane electrode assembly of claim 9, wherein said first ionomer comprises perfluorosulfonic acid and said second ionomer comprises perfluorocyclobutane.

### Claim 11 (depends on 9)

The membrane electrode assembly of claim 9, wherein said second ionomer comprises perfluorocyclobutane.

### Claim 12 (depends on 11)

The membrane electrode assembly of claim 11, wherein said second ionomer further comprises polyvinylidene fluoride.

### Claim 13 (depends on 9)

The membrane electrode assembly of claim 9, wherein said second ionomer comprises sulfonated polyether ether ketone.

### Claim 14 (depends on 9)

The membrane electrode assembly of claim 9, wherein said second ionomer comprises sulfonated poly p-phenylene.

### Claim 15 (depends on 9)

The membrane electrode assembly of claim 9, wherein said first ionomer and said second ionomer comprises the same material.

### Claim 16 (depends on 9)

The membrane electrode assembly of claim 9, wherein at least one of said plurality of electrodes further comprises a proton-conductive substrate to which at least one of said electrode layer and said overcoat layer are coupled.

### Claim 17

A method of fabricating a fuel cell electrode comprising:
coupling an electrode layer comprising a catalyst and an electrochemically-active first ionomer to a substrate; and
placing an overcoat layer disposed on said electrode layer, said overcoat layer comprising a second ionomer with at least one reduced gas crossover characteristic relative to said first ionomer.

### Claim 18 (depends on 17)

The method of claim 17, wherein said first ionomer comprises perfluorosulfonic acid and said second ionomer comprises perfluorocyclobutane.

### Claim 19 (depends on 17)

The method of claim 17, wherein said second ionomer comprises perfluorocyclobutane.

### Claim 20 (depends on 19)

The method of claim 19, wherein said second ionomer further comprises polyvinylidene fluoride.

### Claim 21 (depends on 17)

The method of claim 17, wherein said second ionomer comprises sulfonated polyether ether ketone.

### Claim 22 (depends on 17)

The method of claim 17, wherein said second ionomer comprises sulfonated poly p-phenylene.

### Claim 23 (depends on 17)

The method of claim 17, wherein said first ionomer and said second ionomer comprises the same material.

### Claim 24 (depends on 17)

The method of claim 17, wherein said substrate is a diffusion media.

### Claim 25 (depends on 17)

The method of claim 17, wherein said substrate is a proton conductive membrane.

### Claim 26 (depends on 17)

The method of claim 17, further comprising hot pressing said overcoat layer disposed adjacent said electrode layer to a membrane to form a membrane electrode assembly, said membrane comprising said first ionomer and said overcoat layer comprising said second ionomer.

### Claim 27 (depends on 17)

The method of claim 17, wherein said substrate is a decal substrate, and further comprising removing said decal substrate after said overcoat layer disposed adjacent said electrode layer is hot pressed to said membrane.