Stretched catalyst layer having porous ionomer film and method of producing same

Patent metadata

Field	Value
Publication number	US-2018248198-A1
Application number	US-201715445194-A
Country	US
Kind code	A1
Filing date	Feb 28, 2017
Priority date	Feb 28, 2017
Publication date	Aug 30, 2018
Grant date	—

Abstract

A membrane electrode assembly is provided that includes a polymer electrolyte membrane and a catalyst layer provided on a surface of the polymer electrolyte membrane. The catalyst layer comprises catalyst particles and an ionomer film surrounding each of the catalyst particles. The ionomer film has an oxygen permeability of approximately 6.0×1012 mol/cm/s to 15.0×1012 mol/cm/s at 80° C. and a relative humidity of approximately 30% to 100%.

First claim

What is claimed is:

1 . A membrane electrode assembly comprising:
a polymer electrolyte membrane; and a catalyst layer provided on a surface of the polymer electrolyte membrane, the catalyst layer comprising catalyst particles and an ionomer film surrounding each of the catalyst particles, and the ionomer film having an oxygen permeability of approximately 6.0×10 12 mol/cm/s to 15.0×10 12 mol/cm/s at 80° C. and a relative humidity of approximately 30% to 100%.

2 . The membrane electrode assembly according to claim 1 , wherein
the catalyst particles comprise at least one selected from the group consisting of: ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold and alloys thereof.

3 . The membrane electrode assembly according to claim 2 , wherein
the catalyst particles comprise carbon supported platinum particles.

4 . The membrane electrode assembly according to claim 1 , wherein
the ionomer comprises a fluoropolymer.

5 . The membrane electrode assembly according to claim 4 , wherein
the fluoropolymer is perfluorosulfonic acid.

6 . The membrane electrode assembly according to claim 1 , wherein
the catalyst layer has a porosity of 30 volume % to 40 volume % with respect to a total volume of the catalyst layer.

7 . The membrane electrode assembly according to claim 1 , further comprising
a gas diffusion layer provided on a surface of the catalyst layer that is opposite the polymer electrolyte membrane.

8 . The membrane electrode assembly according to claim 1 , wherein
the catalyst layer is a cathode side catalyst layer.

9 . A fuel cell comprising:
the membrane electrode assembly according to claim 1 , an anode on a first side of the membrane electrode assembly; a cathode on a second side of the membrane electrode assembly; an anode gas diffusion layer on a side of the anode that is opposite the membrane electrode assembly; and a cathode gas diffusion layer on a side of the cathode that is opposite the membrane electrode assembly.

10 . The fuel cell according to claim 8 , wherein
the catalyst layer is a cathode side catalyst layer.

11 . A method for producing a porous catalyst layer in a fuel cell, the method comprising:
providing a catalyst composition on a substrate to form a catalyst layer on the substrate, the catalyst composition comprising catalyst particles and an ionomer film surrounding each of the catalyst particles; stretching the substrate together with the catalyst layer formed thereon to form a stretched substrate and a stretched catalyst layer; and transferring the stretched catalyst layer on the stretched substrate to one of a membrane and a gas diffusion layer.

12 . The method according to claim 11 , wherein
transferring the stretched catalyst layer on the stretched substrate to the one of the membrane and the gas diffusion layer comprises attaching a second substrate to the stretched catalyst layer, removing the stretched substrate, attaching one of the membrane and the gas diffusion layer to the stretched catalyst layer and removing the second substrate.

13 . The method according to claim 11 , wherein
the second substrate is a decal.

14 . The method according to claim 11 , wherein
transferring the stretched catalyst layer on the stretched substrate to the one of the membrane and the gas diffusion layer comprises attaching the one of the membrane and the gas diffusion layer to the stretched catalyst layer and removing the stretched substrate.

15 . The method according to claim 11 , wherein
the substrate with the catalyst layer formed thereon is stretched until the ionomer film has an oxygen permeability of approximately 6.0×10 12 mol/cm/s to 15.0×10 12 mol/cm/s at 80° C. and a relative humidity of approximately 30% to 100%.

16 . The method according to claim 11 , wherein
the substrate is a hydrophobic substrate.

17 . The method according to claim 11 , wherein
the substrate comprises polytetrafluoroethylene.

18 . A method for producing a porous catalyst layer in a fuel cell, the method comprising:
providing a catalyst composition on one of a gas diffusion layer and a membrane layer to form a catalyst layer on the one of the gas diffusion layer and the membrane layer, the catalyst composition comprising catalyst particles and an ionomer film surrounding each of the catalyst particles; and stretching the one of the gas diffusion layer and the membrane layer together with the catalyst layer formed thereon.

19 . The method according to claim 18 , wherein
the catalyst layer is formed on the membrane layer and the catalyst layer is stretched together with the membrane layer.

20 . The method according to claim 18 , further comprising,
combining the membrane layer with a second membrane layer having a thickness greater than that of the membrane layer.

21 . The method according to claim 20 , wherein
the membrane layer and the second membrane layer form a membrane, and the second membrane layer is closer than the membrane layer to an anode side of the membrane.

22 . The method according to claim 18 , wherein
the one of the gas diffusion layer and the membrane layer with the catalyst layer formed thereon is stretched until the ionomer film has an oxygen permeability of approximately 6.0×10 12 mol/cm/s to 15.0×10 12 mol/cm/s at 80° C. and a relative humidity of approximately 30% to 100%.

Assignees

• Nissan North America Inc

Inventors

• Yadav Rameshwar

Classifications

• B32B27/281

  comprising polyimides · CPC title

• B32B27/322

  comprising halogenated polyolefins, e.g. PTFE · CPC title

• H01M4/881

  Electrolytic membranes · CPC title

• H01M8/103

  having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh] · CPC title

• B32B5/16

  characterised by features of a layer formed of particles, e.g. chips, powder {or granules (layer formed of natural mineral particles B32B19/00; layer being formed of wood fibres, chips or particles B32B21/02)} · CPC title