WO2013103338A1

WO2013103338A1 - Reinforced microporous layer

Info

Publication number: WO2013103338A1
Application number: PCT/US2012/020168
Authority: WO
Inventors: Robert Mason Darling
Original assignee: Utc Power Corporation
Priority date: 2012-01-04
Filing date: 2012-01-04
Publication date: 2013-07-11

Abstract

An exemplary fuel cell component includes a microporous layer with ionomer covered carbon particles in a polytetrafluoroethylene matrix. An exemplary fuel cell assembly includes a first electrode layer, a second electrode layer, and a membrane between the electrodes layers. A microporous layer is associated with at least one of the electrode layers and is located on an opposite side of the electrode layer from the membrane. The microporous layer includes ionomer covered carbon particles in a polytetrafluoroethylene matrix.

Description

REINFORCED MICROPOROUS LAYER

BACKGROUND

[0001] Typical fuel cell arrangements include multiple fuel cells placed together in a cell stack assembly (CSA). Each fuel cell generally includes an anode, a cathode, and a membrane between the anode and the cathode. A cathode reactant, such as oxygen, and an anode reactant, such as hydrogen, are used in an electro-chemical reaction at the membrane to produce electrical energy.

[0002] The membrane may sustain damage or wear, which can affect fuel cell efficiency or operation. One possible cause of the membrane damage is that fibers in adjacent layers of the fuel cell, such as a gas diffusion layer, may poke through the membrane.

[0003] It is desirable to avoid such damage to the membrane, but accomplishing that is not without challenges. Making the membrane thicker and stronger is not considered an economical approach. It is also necessary to ensure that any changes to the membrane or adjacent layers will not result in other membrane failure modes such as dry-out.

SUMMARY

[0004] An exemplary fuel cell component includes porous carbon paper having a microporous layer with ionomer covered carbon particles in a polytetrafluoroethylene matrix.

[0005] An exemplary fuel cell assembly includes a first electrode layer, a second electrode layer, and a membrane between the electrodes layers. A microporous layer is associated with at least one of the electrode layers and is located on an opposite side of the electrode layer from the membrane. The microporous layer includes ionomer covered carbon particles in a polytetrafluoroethylene matrix.

[0006] These and other features of a disclosed example can be understood from the following description and the accompanying drawing, which can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWING

[0007] Figure 1 schematically illustrates selected portions of an example fuel cell assembly.

DETAILED DESCRIPTION

[0008] Figure 1 illustrates selected portions of an example fuel cell 10. The illustrated portions include a cathode 12, an anode 14, and a membrane 16, such as a proton exchange membrane (PEM), between the cathode 12 and the anode 14.

[0009] The cathode 12 includes a gas diffusion layer 18, which comprises carbon paper in one example. The cathode 12 also includes a microporous layer 20 and a catalyst layer 22. The catalyst layer 22 comprises a catalyst material on carbon particles in an ionomer matrix. The catalyst layer 22 is located adjacent to the membrane 16 and the microporous layer 20. The gas diffusion layer 18 is on an opposite side of the microporous layer 20 from the catalyst layer 22. In other words, the microporous layer 20 is between the gas diffusion layer 18 and the catalyst layer 22.

[0010] The microporous layer 20 in this example comprises ionomer covered carbon particles in an expanded polytetrafluoroethylene matrix affixed to one side of the carbon paper of the gas diffusion layer 18. The layer is at least partially hydrophilic due to the combination of hydrophilic and hydrophobic components. The ionomer covered carbon particles in the expanded polytetrafluoroethylene matrix provide a barrier against fibers from the gas diffusion layer 18, from poking through the catalyst layer 22 toward the membrane 16.

[0011] In one example, the thickness of the expanded polytetrafluoroethylene matrix is chosen to be greater than the height of the largest expected protrusion from the surface of the carbon paper. The expected height is determined in one example based on a statistically relevant sampling. The diameter of the pores in the expanded polytetrafluoroethylene matrix is smaller than the typical fiber diameter (e.g., about 5 μιη).

[0012] The anode 14 includes a gas diffusion layer 24, which comprises carbon paper in one example, a microporous layer 26, and a catalyst layer 28. The catalyst layer 28 includes a catalyst material on carbon particles coated with ionomer. The catalyst layer 28 is located adjacent the membrane 16. The microporous layer 26 is on an opposite side of the catalyst layer 28 from the membrane 16 between the catalyst layer 28 and the gas diffusion layer 24.

[0013] The microporous layer 26 in this example comprises ionomer covered carbon particles in a polytetrafluoroethylene matrix. In one example, the combination of polytetrafluoroethylene and ionomer covered carbon comprises an expanded polytetrafluoroethylene matrix that is at least partially hydrophilic. The at least partially hydrophilic properties of the microporous layer 26 minimize dehydration of the membrane 16 by attracting water, such as water from a water transport plate (not illustrated) on an opposite side of the gas diffusion layer 24. The ionomer covered carbon particles in the polytetrafluoroethylene matrix provide a barrier against fibers from other layers of the fuel cell 10, such as the gas diffusion layer 24, from poking through the membrane 16.

[0014] Although preferred embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For example, the microporous layer 20 having ionomer covered carbon particles in the expanded polytetrafluoroethylene matrix may be used in connection with a pure oxygen feed to the cathode 12, while a microporous layer 20 without expanded polytetrafluoroethylene matrix maybe be used when the cathode 12 is not fed by a pure oxygen feed. For that reason, the following claims should be studied to determine the scope of legal protection provided to this invention.

Claims

CLAIMS I claim:

1. A fuel cell component comprising:

a microporous layer including ionomer covered carbon particles in a polytetrafluoroethylene matrix.

2. The fuel cell component of claim 1, wherein the microporous layer is affixed to one side of a carbon paper layer.

3. The fuel cell component of claim 1, wherein the polytetrafluoroethylene matrix is an expanded polytetrafluoroethylene matrix.

4. The fuel cell component of claim 1, wherein the microporous layer is at least partially hydrophilic.

5. The fuel cell component of claim 1, wherein the microporous layer is associated with a cathode when the cathode is configured to accept an oxygen feed.

6. A fuel cell assembly comprising:

a first electrode;

a second electrode;

a membrane between the electrodes; and

a microporous layer associated with at least one of the first and second electrodes on an opposite side of the electrode from the membrane, the microporous layer including ionomer covered carbon particles in a polytetrafluoroethylene matrix.

7. The fuel cell assembly of claim 6, wherein the microporous layer is affixed to one side of a carbon paper layer.

8. The fuel cell assembly of claim 6, wherein the polytetrafluoroethylene matrix is an expanded polytetrafluoroethylene matrix.

9. The fuel cell assembly of claim 6, wherein the microporous layer is at least partially hydrophilic.

10. The fuel cell assembly of claim 6, wherein the first electrode is a cathode and the cathode includes a catalyst layer comprising ionomer covered carbon particles.

11. The fuel cell assembly of claim 10, wherein the microporous layer is associated with the cathode when the cathode is configured to accept an oxygen feed.

12. The fuel cell assembly of claim 6, wherein the second electrode is an anode that includes a catalyst layer comprising ionomer covered carbon particles.

13. The fuel cell assembly of claim 6, wherein the membrane is a proton exchange membrane.

14. The fuel cell assembly of claim 6, comprising a gas diffusion layer and wherein the microporous layer is affixed to one side of the gas diffusion layer.

15. The fuel cell assembly of claim 14, wherein the gas diffusion layer comprises carbon paper.