Composite electrode layer for polymer electrolyte fuel cell

Patent metadata

Field	Value
Publication number	US-2019280307-A1
Application number	US-201815915846-A
Country	US
Kind code	A1
Filing date	Mar 8, 2018
Priority date	Mar 8, 2018
Publication date	Sep 12, 2019
Grant date	—

Abstract

A polymer electrolyte membrane fuel cell includes a proton-conductive polymer electrolyte membrane, an anode catalyst layer overlying a first face of the polymer electrolyte membrane, and a cathode catalyst layer overlying a second face of the polymer electrolyte membrane. At least one of the anode catalyst layer or the cathode catalyst layer includes a composite electrode layer that comprises a colloidal or soluble ionomer binder component, a catalyst dispersed along with the colloidal or soluble ionomer binder component, and insoluble ionomer nanofibers disseminated throughout a thickness of the composite electrode layer. The presence of the insoluble ionomer nanofibers within the composite electrode layer may enhance the voltage performance of the fuel cell, particularly at high current densities and/or low relative humidity operating conditions. A method of making a composite electrode layer for a polymer electrolyte membrane fuel cell is also disclosed.

First claim

What is claimed is:

1 . A polymer electrolyte membrane fuel cell comprising:
a proton-conductive solid polymer electrolyte membrane, the polymer electrolyte membrane having a first face and an opposed second face; an anode catalyst layer overlying the first face of the polymer electrolyte; and a cathode catalyst layer overlying the second face of the polymer electrolyte; wherein at least one of the anode catalyst layer or the cathode catalyst layer includes a composite electrode layer that comprises a colloidal or soluble ionomer binder component, a catalyst, and insoluble ionomer nanofibers disseminated throughout a thickness of the composite electrode layer such that at least some of the ionomer nanofibers contact the polymer electrolyte membrane, the ionomer nanofibers being present within the composite electrode layer at a weight percent ranging from 5 to 20 based on a total weight of the composite electrode layer.

2 . The polymer electrolyte membrane fuel cell set forth in claim 1 , wherein the ionomer nanofibers have an aspect ratio of greater than 20.

3 . The polymer electrolyte membrane fuel cell set forth in claim 1 , wherein at least some of the ionomer nanofibers are composed of a sulfonated fluoropolymer.

4 . The polymer electrolyte membrane fuel cell set forth in claim 3 , wherein at least some of the ionomer nanofibers are composed of a copolymer having a polytetrafluoroethylene backbone and perfluoroether pendant side chains that terminate in sulfonic acid groups.

5 . The polymer electrolyte membrane fuel cell set forth in claim 1 , wherein at least the cathode catalyst layer comprises the composite electrode layer.

6 . The polymer electrolyte membrane fuel cell set forth in claim 1 , wherein the colloidal or soluble ionomer binder component comprises a sulfonated fluoropolymer.

7 . The polymer electrolyte membrane fuel cell set forth in claim 1 , wherein the catalyst comprises platinum group metal nanoparticles supported on carbon support particles.

8 . The polymer electrolyte membrane fuel cell set forth in claim 1 , wherein at least some of the ionomer nanofibers extend from a first major face of the composite electrode layer to a second major face of the composite electrode layer and thereby fully traverse the thickness of the composite electrode layer.

9 . The polymer electrolyte membrane fuel cell set forth in claim 1 , further comprising:
a first gas diffusion media layer overlying the anode catalyst layer; a second gas diffusion media layer overlying the cathode catalyst layer; a first electrically-conductive flow field plate overlying the first gas diffusion media layer and configured to deliver hydrogen gas to the anode catalyst layer; and a second electrically-conductive flow field plate overlying the second gas diffusion media layer and configured to deliver an oxidant gas to the cathode catalyst layer.

10 . A polymer electrolyte membrane fuel cell comprising:
a proton-conductive solid polymer electrolyte membrane, the polymer electrolyte membrane having a first face and an opposed second face; an anode catalyst layer overlying the first face of the polymer electrolyte; a cathode catalyst layer overlying the second face of the polymer electrolyte, the cathode catalyst layer being a composite electrode layer that comprises a colloidal or soluble ionomer binder component, a catalyst dispersed along with the soluble ionomer binder component, and ionomer nanofibers disseminated throughout a thickness of the composite electrode layer so as to establish a random network of proton transport pathways across the thickness of the composite electrode layer from a first major face to a second major face of the composite electrode layer; a first gas diffusion media layer overlying the anode catalyst layer; a second gas diffusion media layer overlying the cathode catalyst layer; a first electrically-conductive flow field plate overlying the first gas diffusion media layer and configured to deliver hydrogen gas to the anode catalyst layer; and a second electrically-conductive flow field plate overlying the second gas diffusion media layer and configured to deliver an oxidant gas to the cathode catalyst layer.

11 . The polymer electrolyte membrane fuel cell set forth in claim 10 , wherein the ionomer nanofibers have an aspect ratio of greater than 20.

12 . The polymer electrolyte membrane fuel cell set forth in claim 10 , wherein the ionomer nanofibers are present within the composite electrode layer at a weight percent ranging from 5 wt % to 20 wt % based on a total weight of the composite electrode layer.

13 . The polymer electrolyte membrane fuel cell set forth in claim 10 , wherein the colloidal or soluble ionomer binder component comprises a sulfonated fluoropolymer, and wherein the catalyst comprises platinum group metal nanoparticles supported on carbon support particles.

14 . The polymer electrolyte membrane fuel cell set forth in claim 10 , wherein at least some of the ionomer nanofibers are composed of a sulfonated fluoropolymer.

15 . A method of making a composite electrode layer for a polymer electrolyte membrane fuel cell, the method comprising:
preparing an ionomer solution that includes ionomer particles dissolved or dispersed in a solvent; introducing insoluble ionomer nanofibers into the ionomer solution; introducing a catalyst into the ionomer solution to form an electrode ink slurry; casting the electrode ink slurry onto a surface of a substrate to apply a wet precursor composite layer to the substrate; and removing the solvent from the wet precursor composite layer to derive a composite electrode layer on the surface of the substrate, the composite electrode layer having a first major face and an opposed second major face and including an interpenetrating porous matrix that includes the catalyst, a colloidal or soluble ionomer binder component distributed in and around the catalyst, the insoluble ionomer nanofibers disseminated throughout a thickness of the composite electrode layer such that at least some of the ionomer nanofibers are exposed at the first major face, the second major face, or both of the first and second major faces.

16 . The method set forth in claim 15 , wherein the substrate is a proton-conductive solid polymer electrolyte membrane or a gas diffusion media layer.

17 . The method set forth in claim 15 , wherein the substrate is a decal substrate.

18 . The method set forth in claim 17 , further comprising transferring the composite electrode layer from the decal substrate to a face of a proton-conductive solid polymer electrolyte membrane.

19 . The method set forth in claim 15 , wherein the colloidal or soluble ionomer binder component comprises a sulfonated fluoropolymer, and wherein the catalyst comprises platinum group metal nanoparticles supported on carbon support particles.

20 . The method set forth in claim 15 , wherein at least some of the ionomer nanofibers extend from the first major face of the composite electrode layer to the second major face of the composite electrode layer and thereby fully traverse the thickness of the composite electrode layer.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Ramaswamy Nagappan
• Fuller Timothy
• Kumaraguru Swaminatha

Classifications

• H01M4/88

  Processes of manufacture · CPC title

• H01M8/1004

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

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M4/8652

  as mixture · CPC title

• H01M4/8828

  Coating with slurry or ink · CPC title