Mixed-ionomer electrode

Patent metadata

Field	Value
Publication number	US-2016285106-A1
Application number	US-201615178259-A
Country	US
Kind code	A1
Filing date	Jun 9, 2016
Priority date	Aug 23, 2010
Publication date	Sep 29, 2016
Grant date	—

Abstract

A membrane electrode assembly includes a membrane, an anode catalyst layer and a cathode catalyst layer. The anode catalyst layer is on a first side of the membrane and the cathode catalyst layer is on a second side of the membrane, wherein the second side of the membrane is opposite the first side of the membrane along a first axis. The cathode catalyst layer includes agglomerates formed of a catalyst support supporting catalyst particles, an agglomerate ionomer and an inter-agglomerate ionomer. The agglomerate ionomer surrounds the agglomerates and the inter-agglomerate ionomer is in regions between the agglomerates surrounded by the agglomerate ionomer. The agglomerate ionomer is different than the inter-agglomerate. Methods to produce the catalyst layer are also provided.

First claim

1 . A method of forming a catalyst layer for a membrane electrode assembly, the method comprising:
forming a catalyst ink with a catalyst and a first ionomer in a liquid dispersed form; drying the catalyst ink to form a coated-catalyst powder; grinding the coated-catalyst powder; forming a coated-catalyst ink with the ground coated-catalyst powder and a second ionomer, wherein the second ionomer has a different composition or equivalent weight than the first ionomer; and applying the coated-catalyst ink to a substrate to form a catalyst layer.

2 . The method of claim 1 wherein the first ionomer is a PFSA ionomer and the second ionomer is a hydrocarbon ionomer.

3 . The method of claim 1 wherein the first ionomer has a different composition than the second ionomer.

4 . The method of claim 1 wherein the first ionomer has a different equivalent weight ionomer than the second ionomer.

5 . The method of claim 1 , further comprising:
forming a second catalyst ink with the catalyst and a third ionomer in a liquid dispersed form; drying the second catalyst ink to form a second coated-catalyst powder; grinding the second coated-catalyst powder; forming a second coated-catalyst ink with the ground second coated-catalyst powder and a fourth ionomer, wherein the second ionomer has a different composition or equivalent weight than the fourth ionomer; and applying the second coated-catalyst ink onto the catalyst layer.

6 . The method of claim 1 , further comprising:
forming a second catalyst ink with the catalyst and a third ionomer in a liquid dispersed form, wherein the third ionomer has a different composition or equivalent weight than the first ionomer; drying the second catalyst ink to form a second coated-catalyst powder; grinding the second coated-catalyst powder; forming a second coated-catalyst ink with the ground second coated-catalyst powder and a fourth ionomer; and applying the second coated-catalyst ink onto the catalyst layer.

7 . The method of claim 1 , further comprising:
prior to grinding the coated-catalyst powder, forming an intermediate catalyst ink with the coated-catalyst powder and an intermediate ionomer in a liquid dispersed form; and drying the intermediate catalyst ink such that the resulting coated-catalyst powder to be subsequently ground comprises a plurality of ionomer films.

8 . The method of claim 1 wherein the catalyst includes catalyst particles supported on catalyst supports, and further comprising:
controlling a ratio of the first ionomer to the catalyst support to form an ionomer film between about 1 to about 15 nanometers.

9 . The method of claim 1 wherein the catalyst includes catalyst particles supported on catalyst supports, and further comprising:
controlling a ratio of the first ionomer to the catalyst support to form an ionomer film between about 2 to about 10 nanometers.

10 . The method of claim 1 wherein drying the catalyst ink to form the coated-catalyst powder includes heating the catalyst ink at a temperature between about 100 and about 150 degrees Celsius for between about 30 and about 60 minutes.

11 . The method of claim 1 , further comprising:
controlling a ratio of the second ionomer to the ground coated-catalyst powder to form the catalyst layer with a thickness between about 5 and about 15 microns.

12 . A method of forming a catalyst layer for a membrane electrode assembly, the method comprising:
forming a catalyst ink with a catalyst and an agglomerate ionomer in a liquid dispersed form; drying the catalyst ink to form a coated-catalyst powder; grinding the coated-catalyst powder; forming a coated-catalyst ink with the ground coated-catalyst powder and an inter-agglomerate ionomer, wherein the inter-agglomerate ionomer has a different composition or equivalent weight than the agglomerate ionomer; and applying the coated-catalyst ink to a substrate to form a catalyst layer comprising a plurality of agglomerates surrounded by and in direct contact with the agglomerate ionomer and with the inter-agglomerate ionomer provided in regions between the agglomerates and in contact with the agglomerate ionomer surrounding the agglomerates such that the inter-agglomerate ionomer supports the agglomerate ionomer covered agglomerates in a dispersed manner throughout the catalyst layer.

Assignees

• Audi Ag

Inventors

• Madden Thomas H
• Darling Robert Mason
• Perry Michael L

Classifications

• H01M4/8807

  Gas diffusion layers · CPC title

• H01M4/8828 Primary

  Coating with slurry or ink · CPC title

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M8/1007

  with both reactants being gaseous or vaporised (H01M8/12 takes precedence) · CPC title