Fuel cell bipolar plate including corrosion-resistant ferric oxide layer

Patent metadata

Field	Value
Publication number	US-11205783-B2
Application number	US-201916527847-A
Country	US
Kind code	B2
Filing date	Jul 31, 2019
Priority date	Jul 31, 2019
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

Corrosion-resistant oxide films for use with proton exchange membrane fuel cells are described. Bipolar plates of proton exchange membrane fuel cells are subject to highly-acidic environments that can degrade the bulk material and associated properties of the bipolar plate leading to reduced proton exchange membrane fuel cell lifetimes. Materials, structures, and techniques for increasing the corrosion resistance of bipolar plates are disclosed. Such materials include substrates having a surface portion, which includes an Fe 2 O 3 oxide layer having (110), (012), or (100) Fe 2 O 3 surface facets configured to impart corrosion-resistance properties to the substrate.

First claim

What is claimed is:

1. A corrosion-resistant substrate comprising:
a bulk portion; and
a surface portion including an Fe 2 O 3 oxide layer configured to impart corrosion-resistance properties to the substrate;
wherein the Fe 2 O 3 oxide layer of the surface portion comprises a first surface-facet group including (110), (012), or (100) Fe 2 O 3 surface facets and a second surface-facet group including (001) or (101) Fe 2 O 3 surface facets.

2. The substrate of claim 1 , wherein the Fe 2 O 3 oxide layer is between 0.001 and 0.5 μm thick.

3. The substrate of claim 1 , wherein the (110), (012), and (100) Fe 2 O 3 surface facets of the first surface-facet group cover greater than 50% of the surface portion of the substrate.

4. The substrate of claim 1 , wherein the surface portion further includes a protective coating comprising MgO, Al 2 O 3 , TiO 2 , or ZrO 2 .

5. The substrate of claim 1 , wherein the surface portion further includes a protective coating having a structure described by:
AB O x ,
where
A is Mg, Al, Ti, or Zr,
B is Zn, Sn, Cr, or Mo, and
x is an integer ranging from 1 to 8.

6. A corrosion-resistant substrate comprising:
a bulk portion; and
a surface portion including an Fe 2 O 3 oxide layer comprising a first surface-facet group including (110), (012), or (100) Fe 2 O 3 surface facets and a second surface-facet group including (001) or (101) Fe 2 O 3 surface facets, the surface portion configured to impart corrosion-resistance properties to the substrate;
wherein the Fe 2 O 3 oxide layer is between 0.001 and 0.5 μm thick and the (110), (012), and (100) Fe 2 O 3 surface facets of the first surface-facet group cover greater than 50% of the surface portion of the substrate, and
wherein the surface portion further includes a protective coating comprising MgO, Al 2 O 3 , TiO 2 , or ZrO 2 .

7. The substrate of claim 1 , wherein the bulk portion is stainless steel comprising between 10 and 20% chromium and 5 to 10% nickel.

8. The substrate of claim 1 , wherein the substrate's electrical conductivity is greater than about 100 S cm −1 .

9. The substrate of claim 1 , wherein the surface portion includes a corrosion resistance of less than 1 μA cm −2 at 80° C., pH between 2 and 3 and in the presence of about 0.1 ppm HF.

10. The substrate of claim 1 , wherein the Fe 2 O 3 oxide layer is between 0.15 and 0.3 μm thick.

11. The substrate of claim 1 , wherein the Fe 2 O 3 oxide layer comprises between 70% and 90% of the first surface-facet group and between 10% and 30% of the second surface-facet group.

12. A bipolar plate for a proton exchange membrane fuel cell comprising:
a metal substrate having a bulk portion and a surface portion including an Fe 2 O 3 oxide layer comprising a first surface-facet group including (110), (012), or (100) Fe 2 O 3 surface facets and a second surface-facet group including (001) or (101) Fe 2 O 3 surface facets, the surface portion configured to impart corrosion-resistance properties to the substrate;
wherein the Fe 2 O 3 oxide layer is between 0.001 and 0.5 μm thick, a corrosion resistance of the surface portion is less than 1 μA cm −2 at 80° C., pH between 2 and 3 and in the presence of about 0.1 ppm HF, and the surface portion further includes a protective coating having a structure described by:
AB O x ,

where
A is Mg, Al, Ti, or Zr,
B is Zn, Sn, Cr, or Mo, and
x is an integer ranging from 1 to 8.

13. The bipolar plate of claim 12 , wherein the electrical conductivity of the metal substrate is greater than about 100 S cm −1 .

14. The bipolar plate of claim 12 , wherein the bulk portion is stainless steel comprising between 10 and 20% chromium and 5 to 10% nickel.

15. The bipolar plate of claim 12 , wherein Fe 2 O 3 oxide layer is between 0.15 and 0.3 μm thick.

16. The bipolar plate of claim 12 , wherein the Fe 2 O 3 oxide layer comprises between 70% and 90% of the first surface-facet group and between 10% and 30% of the second surface-facet group.

17. A method of producing a corrosion-resistant stainless steel substrate, the method comprising:
cleaning a stainless steel substrate with organic solvent; and
electrochemically oxidizing the stainless steel substrate to form a corrosion-resistant surface portion including an Fe 2 O 3 oxide layer comprising a first surface-facet group including (110), (012), or (100) Fe 2 O 3 and a second surface-facet group including (001) or (101) Fe 2 O 3 surface facets, the Fe 2 O 3 oxide layer being between 0.001 and 0.5 μm thick, the (110), (012), or (100) Fe 2 O 3 surface facets of the first surface-facet group covering greater than 50% of the surface portion of the substrate.

18. The method of claim 17 , further comprising depositing a protective coating comprising MgO, Al 2 O 3 , TiO 2 , or ZrO 2 onto the surface portion of the substrate.

19. The method of claim 17 , further comprising depositing a protective coating having a structure described by:
AB O x ,
where
A is Mg, Al, Ti, or Zr,
B is Zn, Sn, Cr, or Mo, and
x is an integer ranging from 1 to 8.

Assignees

• Bosch Gmbh Robert

Inventors

• Kim Soo
• Kornbluth Mordechai
• Mailoa Jonathan
• Samsonidze Georgy
• Cheng Lei
• Hellstrom Sondra
• Kozinsky Boris
• Craig Nathan

Classifications

• H01M8/021

  Alloys based on iron · CPC title

• B08B3/08

  the liquid having chemical or dissolving effect · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M8/0228 Primary

  in the form of layered or coated products · CPC title

• H01M8/0215

  Glass; Ceramic materials · CPC title