Fluoropolymer ionomers with reduced catalyst poisoning and articles therefrom

Patent metadata

Field	Value
Publication number	US-12199290-B2
Application number	US-201917288021-A
Country	US
Kind code	B2
Filing date	Oct 25, 2019
Priority date	Dec 21, 2018
Publication date	Jan 14, 2025
Grant date	Jan 14, 2025

Abstract

Described herein is a coating composition comprising: (a) a metal catalyst, wherein the metal catalyst comprises at least one of platinum, ruthenium, iridium, and alloys and combinations thereof; (b) an at least highly fluorinated ionomer comprising a polymer backbone and a plurality of first side chains pendant therefrom, wherein the first side chain comprises at least one protogenic group, wherein the protogenic group is selected from a sulfonic acid, a bis(sulfonyl)imide, a sulfonamide, a sulfonyl methide, and salts and combinations thereof, and wherein the polymer backbone comprises an average of at least 14 carbon atoms between adjacent first side chains along the polymer backbone; and (c) a solvent. Such coating compositions may be used to make electrodes for electrochemical cells and have been shown to have reduced poisoning of the catalyst.

First claim

What is claimed is:

1. A coating composition comprising:
(a) a metal catalyst, wherein the metal catalyst comprises at least one of platinum, ruthenium, iridium, and alloys and combinations thereof;
(b) an at least highly fluorinated ionomer comprising a polymer backbone and a plurality of first side chains pendant therefrom, wherein the first side chain comprises at least two protogenic groups, wherein each protogenic group is selected from a sulfonic acid, a bis(sulfonyl)imide, a sulfonamide, a sulfonyl methide, and salts thereof, and wherein the polymer backbone comprises an average of at least 14 carbon atoms between adjacent first side chains along the polymer backbone; and
(c) a solvent.

2. The composition according to claim 1 , wherein the first side chain is —O—(CF 2 ) m —O—CF—[CF 2 SO 3 Y] 2 wherein m is 2, 3, 4, 5, or 6; and Y is H or a counterion comprising an alkali metal, an alkaline earth metal, a transition metal, or combinations thereof.

3. The composition according to claim 1 , wherein the at least highly fluorinated ionomer has an equivalent weight of less than 928 g/mol.

4. The composition according to claim 1 , wherein the at least highly fluorinated ionomer has an ion conductivity of at most 100 mS/cm at 50% relative humidity and at 80° C.

5. The composition according to claim 1 , wherein the at least highly fluorinated ionomer comprises at least one bis(sulfonyl)imide and the at least highly fluorinated ionomer has an equivalent weight of at least 350 g/mol.

6. The composition according to claim 1 , wherein the at least highly fluorinated ionomer comprises at least one sulfonic acid or salt thereof and the at least highly fluorinated ionomer has an equivalent weight of at least 1100 g/mol.

7. The composition according to claim 1 , wherein the at least highly fluorinated ionomer comprises at least one second side chain, wherein the second side chain is not protogenic.

8. The composition according to claim 1 , wherein the metal catalyst is disposed on a support.

9. The composition according to claim 1 , wherein the composition comprises a ratio of the at least highly fluorinated ionomer to the metal catalyst is at least 0.01 to at most 20 by mass.

10. The composition according to claim 1 , wherein the composition further comprises an additive.

11. The composition according to claim 1 , wherein the solvent comprises at least one of an alcohol, a polyalcohol, a ketone, water, a fluorinated solvent, and combinations thereof.

12. The composition according to claim 1 , wherein the composition comprises 1 to 40 wt % solids.

13. An article comprising a substrate with an electrode coating thereon, wherein the electrode coating comprises
(a) a metal catalyst phase, wherein the metal catalyst phase comprises at least one of platinum, ruthenium, iridium, and alloys and combinations thereof; and
(b) an at least highly fluorinated ionomer layer comprising a polymer backbone and a plurality of first side chains pendant therefrom, wherein the first side chain comprises at least two protogenic groups, wherein each protogenic group is a sulfonic acid, a bis(sulfonyl)imide, a sulfonamide, a sulfonyl methide, or salts thereof, and wherein the polymer backbone comprises an average of at least 14 carbon atoms between adjacent first side chains along the polymer backbone, and optionally, wherein the substrate is a gas diffusion layer, a liner, or an ion conductive membrane.

14. The article of claim 13 , wherein the electrode coating has a thickness of at least 0.1 micrometer and at most 100 micrometers.

15. The composition of claim 7 , wherein the second side chain comprises at least one of a perfluorinated alkyl ether, a perfluorinated alkyl polyether, and a perfluorinated alkyl group.

16. The composition of claim 8 , wherein the support is at least one of carbon particles, acicular particles, and a metal organic framework.

17. The composition of claim 10 , wherein the additive is at least one of carbon particles, acicular particles, and a metal organic framework.

18. The article of claim 13 , wherein the substrate is a gas diffusion layer, a liner, or an ion conductive membrane.

19. The coating of claim 1 , wherein the first side chain comprises a plurality of protogenic groups.

20. The coating of claim 1 , wherein the polymer backbone comprises an average of at least 16 carbon atoms between adjacent first side chains along the polymer backbone.

21. The coating of claim 1 , wherein the polymer backbone comprises an average of no more than 24 carbon atoms between adjacent first side chains along the polymer backbone.

Assignees

• 3M Innovative Properties Company

Inventors

• Haug Andrew T
• Abulu John E
• Lindell Matthew J
• Matthews Tyler S
• Steinbach Andrew J L
• Sun Fuxia
• Yandrasits Michael A

Classifications

• H01M4/8828

  Coating with slurry or ink · CPC title

• H01M4/8668 Primary

  Binders · CPC title

• C09D141/00

  Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur; Coating compositions based on derivatives of such polymers · CPC title

• C09D127/18

  Homopolymers or copolymers of tetrafluoroethene · CPC title

• Y02E60/50

  Fuel cells · CPC title