Catalyst coated electrolyte membrane, fuel cell including the same, method of preparing the catalyst coated electrolyte membrane

Abstract

A catalyst coated electrolyte membrane including an anode catalyst layer and a cathode catalyst layer at opposite sides thereof, respectively, wherein micro cracks of the anode catalyst layer or cathode catalyst layer occupy 0.01-1 area % of the total area of the respective anode catalyst layer or cathode catalyst layer, a fuel cell including the same, and a method of preparing the catalyst coated electrolyte membrane. In the catalyst coated electrolyte membrane, micro cracks of the cathode catalyst layer or the anode catalyst layer can be minimized and thus the resistance between the electrode catalyst layer and an electrolyte membrane can be minimized, and crossover of a fuel, such as methanol, ethanol, other alcohols, methane, etc., to a cathode electrode can be minimized, and thus the catalyst coated electrolyte membrane has improved performance and durability.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIGS. 1A and 1B are surface images of a conventional catalyst coated electrolyte membrane;

FIG. 2 schematically illustrates a possible fuel crossover resulting from micro cracks of a conventional catalyst coated electrolyte membrane;

FIGS. 3A and 3B are surface images of catalyst coated electrolyte membranes prepared according to Example 1 and Example 2, respectively;

FIG. 4 schematically illustrates a method of preparing a catalyst coated electrolyte membrane according to an embodiment of the present invention;

FIG. 5 schematically illustrates a pretreatment process of an electrolyte membrane in the method illustrated in FIG. 4;

FIG. 6 is a graph showing performance and durability on days of operation of a fuel cell including the catalyst coated electrolyte membrane prepared according to Example 1; and

FIG. 7 is a graph showing performance and durability on days of operation of a fuel cell including a catalyst coated electrolyte membrane prepared according to Comparative Example.

Claims

1. A catalyst coated electrolyte membrane comprising an anode catalyst layer and a cathode catalyst layer at opposite sides thereof, respectively, wherein micro cracks of the anode catalyst layer or cathode catalyst layer occupy 0.01-1 area % of the total area of the respective anode catalyst layer or cathode catalyst layer.

2. A fuel cell including the catalyst coated electrolyte membrane of claim 1.

3. The fuel cell of claim 2, wherein the fuel is methanol, ethanol, or a combination thereof.

4. The fuel cell of claim 2, further comprising: a stack structure comprising: a plurality of unit cells, wherein each unit cell includes the catalyst coated electrolyte membrane of claim 1, an anode diffusion electrode, a cathode diffusion electrode, and a separator.

5. A fuel cell system, comprising: the fuel cell of claim 4;a fuel processor;a fuel tank; anda fuel pump.

6. A method of preparing a catalyst coated electrolyte membrane, the method comprising: preparing an anode catalyst layer transfer membrane by coating an anode catalyst layer forming composition on a support and then drying the coated composition;preparing a cathode catalyst layer transfer membrane by coating a cathode catalyst layer forming composition on a support and then drying the coated composition;pre-treating a Na+-electrolyte membrane to obtain an H+-electrolyte membrane;pre-heating the anode catalyst layer transfer membrane, the cathode catalyst layer transfer membrane, and the H+-electrolyte membrane under an atmospheric pressure; andsequentially stacking and hot pressing the preheated anode catalyst layer transfer membrane, the preheated H+-electrolyte membrane, and the preheated cathode catalyst layer transfer membrane to respectively transfer the preheated anode catalyst layer and the preheated cathode catalyst layer to opposite surfaces of the H+-electrolyte membrane.

7. The method of claim 6, wherein, in the pre-treating, the H+-electrolyte membrane is sequentially immersed in an H2O2 solution, in an H2SO4 solution, then in a deionized water, and then dried.

8. The method of claim 7, wherein the concentration of the H2O2 solution is in a range of 5-15%, and the mol number of the H2SO4 solution is in a range of 0.5-2 mol.

9. The method of claim 7, wherein the H+-electrolyte membrane is immersed in the H2O2 solution for 1-1.5 hours, in the H2SO4 solution for 0.5-1.5 hours, and then in the deionized water for 1-2 hours.

10. The method of claim 7, wherein the drying is performed at 50° C.-70° C. for 30 minutes-1 hour.

11. The method of claim 6, wherein the preheating is performed at 100° C.-140° C. for 2-10 minutes.

12. The method of claim 6, wherein the hot pressing is performed at 100° C.-140° C. and a pressure of 0.1-1.5 tons/in2 for 5-10 minutes.

13. The method of claim 6, wherein the hot pressing is performed at 100C.-140° C. and a pressure of 0.1-1.0 tons/in2 for 5-10 minutes.

14. A method of preparing a catalyst coated electrolyte membrane, comprising: preheating one or more electrode catalyst layer transfer membranes and an H+-electrolyte membrane under an atmospheric pressure;layering the preheated H+-electrolyte membrane with the one or more preheated electrode catalyst layer transfer membranes, wherein one or more electrode catalyst layers of the respective electrode catalyst layer transfer membranes contact the H+-electrolyte membrane; andhot pressing the layered membranes to transfer the one or more electrode catalyst layers to the H+-electrolyte membrane.

15. The method of claim 14, wherein one electrode catalyst layer is transferred to each surface of the H+-electrolyte membrane.

16. The method of claim 14, wherein the preheating of one or more electrode catalyst layer transfer membranes comprises: preparing the electrode catalyst layer transfer membrane by coating an electrode catalyst layer forming composition on a support and then drying the coated composition.

17. The method of claim 14, wherein the preheating of the H+-electrolyte membrane comprises: pre-treating a Na+-electrolyte membrane to obtain an H+-electrolyte membrane by sequentially immersing the Na+-electrolyte membrane in an H2O2 solution, in an H2SO4 solution, then in a deionized water, and then dried.

18. The method of claim 16, wherein the preparing of the electrode catalyst layer transfer membrane comprises: mixing a catalyst, a solvent, and a binder to prepare the electrode catalyst layer forming composition.

19. The method of claim 18, wherein the preparing of the electrode catalyst layer transfer membrane further comprises: preparing a film of one of polyethyleneterephthalate or KAPTON as the support;using a proton conductive resin as the binder; andpreparing the catalyst using one of, Pt, Ru, Pd, Rh, Ir, Os, Ni, a mixture thereof, an alloy thereof, or a supported catalyst thereof, wherein a catalyst support is one of, carbon black, acetylene black, activated carbon, or graphite.

20. The method of claim 18, wherein the solvent is one of water, alcohol or a combination thereof.

21. The method of claim 20, wherein the solvent is one of water, alcohol, 1-propanol, ethyleneglycol, 2-propanol, or a combination thereof, wherein an amount of the solvent is in a range of 5-250 parts by weight based on 100 parts by weight of the catalyst.

22. The method of claim 21, wherein when the solvent is water, the amount of water is in a range of 5-10 parts by weight based on 100 parts by weight of the catalyst;when the solvent is 1-propanol, the amount of the 1-propanol is in a range of 150-250 parts by weight based on 100 parts by weight of the catalyst;when the solvent is ethylene glycol, the amount of ethylene glycol is in a range of 100-200 parts by weight based on 100 parts by weight of the catalyst;when the solvent is 2-propanol, the amount of 2-propanol is in a range of 150-250 parts by weight based on 100 parts by weight of the catalyst.

23. A catalyst coated electrolyte membrane comprising an electrode catalyst layer on a first side thereof, wherein micro cracks of the electrode catalyst layer occupy 0.01-1 area % of the total area of the electrode catalyst layer.

24. The catalyst coated electrolyte membrane of claim 23, further comprising the electrode catalyst layer on a second side of the catalyst coated electrolyte membrane.

25. The catalyst coated electrolyte membrane of claim 23, wherein the electrode catalyst layer further comprises: a catalyst of one of, Pt, Ru, Pd, Rh, Ir, Os, Ni, a mixture thereof, an alloy thereof, or a supported catalyst thereof, wherein a catalyst support of the supported catalyst is one of carbon black, acetylene black, activated carbon, graphite, or a combination thereof.

26. A fuel cell including the catalyst coated electrolyte membrane of claim 23.

27. The fuel cell of claim 26, wherein the fuel is one of methanol, ethanol, or a combination thereof.

28. The fuel cell of claim 26, further comprising: a stack structure comprising: a plurality of unit cells, wherein each unit cell includes the catalyst coated electrolyte membrane of claim 1, an anode diffusion electrode, a cathode diffusion electrode, and a separator.

29. A fuel cell system, comprising: the fuel cell of claim 28;a fuel processor;a fuel tank; anda fuel pump.