# US 8,785,080 B2 · Passivated metallic bipolar plates and a method for producing the same

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- Number: US 8,785,080 B2
- Document ID: US8785080B2
- Status: Granted
- Kind: B2
- Application number: 11/968,798
- Filed: 2008-01-03
- Published: 2009-07-09
- Granted: 2014-07-22
- Earliest claimed: 2008-01-03
- Assignees: GM Global Technology Operations LLC
- Applicants: Mahmoud H. Abd Elhamid; Gayatri Vyas Dadheech; Youssef M. Mikhail
- Inventors: Mahmoud H. Abd Elhamid; Gayatri Vyas Dadheech; Youssef M. Mikhail
- Web page: https://patentgrep.com/patent/US8785080B2

## CPC

- H01M 8/0228: in the form of layered or coated products
- H01M 8/0208: Alloys
- H01M 8/0245: in the form of layered or coated products
- H01M 8/021: Alloys based on iron
- H01M 2008/1095: {Fuel cells with polymeric electrolytes}
- Y02E 60/50: Fuel cells
- 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

## Abstract

A method including providing a substrate; treating the substrate to form a passive layer, wherein the passive layer has a thickness of at least 3 nm; and depositing an electrically conductive coating over the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.

## Claims

### Claim 1

A method comprising:
providing a first fuel cell bipolar plate substrate having a reactant gas flow field defined in a surface;
treating the first substrate to form a passive oxide layer on the substrate with a thickness of at least 3 nm, wherein the treating comprises at least one of soaking the substrate in boiling de-ionized water, or applying to the substrate a heat treatment above 400° C.;
depositing an electrically conductive metal coating on the passive oxide layer on the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.

### Claim 2 (depends on 1)

A method as set forth in claim 1 wherein the treating the first substrate further comprises removing residual iron from the first substrate.

### Claim 3 (depends on 1)

A method as set forth in claim 1 wherein the depositing comprises at least one of magnetron sputtering, electron beam evaporation, or ion assisted deposition.

### Claim 4 (depends on 1)

A method as set forth in claim 1 wherein the passive layer has a thickness such that the thickness will not increase subsequent to the treating of the first substrate to form the passive layer when used in a fuel cell.

### Claim 5 (depends on 1)

A method as set forth in claim 1 wherein the electrically conductive metal coating comprises at least one of platinum, ruthenium, or iridium.

### Claim 6 (depends on 1)

A method as set forth in claim 1 wherein the first substrate comprises at least one of stainless steel, titanium, aluminum, or nickel base alloy.

### Claim 7 (depends on 1)

A method as set forth in claim 1 wherein the first substrate comprises a bipolar plate.

### Claim 8 (depends on 1)

A method as set forth in claim 1 wherein the electrically conductive metal coating has a thickness of about 0.1 nm to about 2 nm.

### Claim 9 (depends on 1)

A method as set forth in claim 1 further comprising:
providing a second fuel cell substrate, wherein the first fuel cell substrate comprises a first bipolar plate and wherein the second fuel cell substrate comprises a second bipolar plate;
providing a soft goods portion comprising a polymer electrolyte membrane comprising a first face and a second face, a cathode electrode overlying the first face of the polymer electrolyte membrane, a first gas diffusion media layer overlying the cathode electrode, an anode electrode underlying the second face of the polymer electrolyte membrane, and a second gas diffusion media layer underlying the anode electrode; and
wherein the first bipolar plate overlies the first gas diffusion media layer, and the second bipolar plate underlies the second gas diffusion media layer.

### Claim 10 (depends on 9)

A method as set forth in claim 9 further comprising providing a first microporous layer between the first gas diffusion media layer and the cathode electrode.

### Claim 11 (depends on 9)

A method as set forth in claim 9 further comprising providing a second microporous layer between the second gas diffusion media layer and the anode electrode.

### Claim 12 (depends on 1)

A method as set forth in claim 1 wherein the electrically conductive metal coating consists essentially of platinum, ruthenium, or iridium.

### Claim 13 (depends on 1)

A method as set forth in claim 1 wherein the electrically conductive metal coating is porous.

### Claim 14 (depends on 9)

A method as set forth in claim 9 wherein one of the first gas diffusion media layer and the second gas diffusion media layer includes a woven carbon cloth treated with a hydrophobic material.

### Claim 15 (depends on 9)

A method as set forth in claim 9 wherein one of the first gas diffusion media layer and the second gas diffusion media layer has an average pore size of between 5 and 40 micrometers.

### Claim 16 (depends on 9)

A method as set forth in claim 9 wherein one of the first gas diffusion media layer and the second gas diffusion media layer has an thickness of between 100 and 500 micrometers.

### Claim 17 (depends on 10)

A method as set forth in claim 10 wherein the first microporous layer comprises a plurality of particles and a binder, wherein the binder and the plurality of particles are in a liquid phase comprising a mixture of organic solvent and water.

### Claim 18 (depends on 17)

A method as set forth in claim 17 wherein the first microporous layer is dried and results in the first microporous layer comprising 60-90 weight percent particles and 10-40 weight percent binder.

### Claim 19

A product comprising:
a first fuel cell bipolar plate substrate having a reactant gas flow field defined in a surface comprising a passive oxide layer thereon, wherein the passive layer has a thickness of at least 3 nm; and
a porous electrically conductive metal coating with the proviso that the electrically conductive metal coating does not include gold or platinum or vanadium on the passive oxide layer on the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.

### Claim 20 (depends on 19)

A product as set forth in claim 19 wherein the electrically conductive metal coating comprises at least one of ruthenium, or iridium.

### Claim 21 (depends on 19)

A product as set forth in claim 19 wherein the substrate comprises at least one of stainless steel, titanium, aluminum, or nickel base alloy.

### Claim 22 (depends on 19)

A product as set forth in claim 19 wherein the electrically conductive metal coating has a thickness of about 0.1 nm to about 2 nm.

### Claim 23 (depends on 19)

A product as set forth in claim 19 wherein the first fuel cell substrate comprises a first bipolar plate.

### Claim 24 (depends on 19)

A product as set forth in claim 19 further comprising:
a second fuel cell substrate, wherein the first fuel cell substrate comprises a first bipolar plate and the second fuel cell substrate comprises a second bipolar plate;
a soft goods portion comprising a polymer electrolyte membrane comprising a first face and a second face, a cathode electrode overlying the first face of the polymer electrolyte membrane, a first gas diffusion media layer overlying the cathode electrode, an anode electrode underlying the second face of the polymer electrolyte membrane, and a second gas diffusion media layer underlying the anode electrode;
wherein the first bipolar plate overlies the first gas diffusion media layer, and the second bipolar plate underlies the second gas diffusion media layer.

### Claim 25 (depends on 24)

A product as set forth in claim 24 further comprising a first microporous layer between the first gas diffusion media layer and the cathode electrode.

### Claim 26 (depends on 24)

A product as set forth in claim 24 further comprising a second microporous layer between the second gas diffusion media layer and the anode electrode.

### Claim 27 (depends on 19)

A product as set forth in claim 19 wherein the electrically conductive metal coating comprises at least one of ruthenium or iridium; wherein the substrate comprises at least one of stainless steel, titanium, aluminum, or nickel base alloy; and wherein the electrically conductive coating has a thickness of about 0.1 nm to about 2 nm.

### Claim 28 (depends on 19)

A product as set forth in claim 19 wherein the electrically conductive metal coating consists essentially of ruthenium, or iridium.

### Claim 29 (depends on 25)

A product as set forth in claim 25 wherein the first microporous layer comprises a plurality of particles and a binder, wherein the binder and the plurality of particles are in a liquid phase comprising a mixture of organic solvent and water.

### Claim 30 (depends on 29)

A product as set forth in claim 29 wherein the first microporous layer is dried and results in the first microporous layer comprising 60-90 weight percent particles and 10-40 weight percent binder.

### Claim 31

A method comprising:
providing a first fuel cell bipolar plate substrate having a reactant gas flow field defined in a surface;
treating the substrate to form a passive oxide layer on the substrate with a thickness of at least 3 nm, wherein the treating comprises contacting the substrate with a nitric acid solution;
depositing an electrically conductive metal coating with the proviso that the electrically conductive metal coating does not include gold or platinum or vanadium on the passive oxide layer on the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.

### Claim 32

A method comprising:
providing a first fuel cell bipolar plate substrate having a reactant gas flow field defined in a surface;
treating the substrate to form a passive oxide layer on the substrate with a thickness of at least 3 nm, wherein the treating comprises soaking the substrate in boiling de-ionized water;
depositing an electrically conductive metal coating on the passive oxide layer on the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.

### Claim 33

A method comprising:
providing a first fuel cell bipolar plate substrate having a reactant gas flow field defined in a surface;
treating the first substrate to form a passive oxide layer on the substrate with a thickness of at least 3 nm, wherein the treating comprises applying to the substrate a heat treatment above 400° C.;
depositing an electrically conductive metal coating on the passive oxide layer on the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.

### Claim 34

A method comprising:
providing a first fuel cell bipolar plate substrate having a reactant gas flow field defined in a surface;
treating the first substrate to form a passive oxide layer on the substrate with a thickness of at least 3 nm, wherein the treating comprises at least one of contacting the substrate with a nitric acid solution, soaking the substrate in boiling de-ionized water, or applying to the substrate a heat treatment above 400° C.;
depositing an electrically conductive metal coating with the proviso that the electrically conductive metal coating does not include gold or platinum or vanadium on the passive oxide layer on the substrate, wherein the coating has a thickness of about 0.1 nm to about 50 nm.