Cathode for fuel cells and method of manufacturing membrane electrode assembly having the same

Patent metadata

Field	Value
Publication number	US-2018183083-A1
Application number	US-201715848880-A
Country	US
Kind code	A1
Filing date	Dec 20, 2017
Priority date	Dec 28, 2016
Publication date	Jun 28, 2018
Grant date	—

Abstract

A cathode for fuel cells includes a carbon support, a platinum catalyst supported on the carbon support and an ionomer surrounding the carbon support and the platinum catalyst, wherein the ionomer is removed from the surface of the platinum catalyst. The cathode for fuel cells has a structure in which an ionomer film coating the surface of the platinum catalyst and thus acting as oxygen transfer resistance is removed from the surface of the platinum catalyst and, thus, mass transfer resistance (oxygen diffusion resistance) may be reduced and performance of a fuel cell may be improved. Further, the cathode having a low amount of platinum used due to improvement in platinum utilization may effectively execute oxygen transfer and thus increase the amount of platinum participating in catalysis, as compared to conventional cathodes.

First claim

What is claimed is:

1 . A cathode for fuel cells comprising:
a carbon support; a platinum catalyst supported on the carbon support; and an ionomer surrounding the carbon support and the platinum catalyst, wherein the ionomer is removed from a surface of the platinum catalyst.

2 . The cathode for fuel cells of claim 1 , wherein the carbon support is a highly crystalline carbon support having a high degree of graphitization.

3 . The cathode for fuel cells of claim 1 , wherein the carbon support and the platinum catalyst are surrounded with the ionomer such that only the surface of the platinum catalyst is not coated with the ionomer.

4 . A membrane electrode assembly for fuel cells comprising the cathode of claim 1 .

5 . A fuel cell comprising the membrane electrode assembly of claim 4 .

6 . A method of manufacturing a membrane electrode assembly for fuel cells, the method comprising:
coating a surface of a platinum catalyst supported on a carbon support with an amorphous carbon layer by mixing the platinum catalyst supported on the carbon support with a polymer containing carbon and a solvent, and carbonizing the platinum catalyst mixed with the polymer and the solvent; preparing an electrode forming slurry by mixing the carbonized platinum catalyst with an ionomer; preparing a cathode using the slurry; manufacturing a membrane electrode assembly using the prepared cathode, an electrolyte membrane and an anode; and removing the ionomer from the surface of the platinum catalyst of the cathode by oxidizing the amorphous carbon layer coating the surface of the platinum catalyst.

7 . The method of claim 6 , wherein the carbon support is a highly crystalline carbon support having a high degree of graphitization.

8 . The method of claim 6 , wherein the polymer containing carbon is polydopamine.

9 . The method of claim 6 , wherein in carbonization of the platinum catalyst mixed with the polymer containing carbon and the solvent, the polymer containing carbon coating the platinum catalyst forms the amorphous carbon layer by drying a mixing solution, acquired by mixing the platinum catalyst supported on the carbon support with the polymer containing carbon and the solvent, and then heating an acquired powder under a nitrogen atmosphere.

10 . The method of claim 6 , wherein in carbonization of the platinum catalyst mixed with the polymer containing carbon and the solvent, the polymer containing carbon coating the platinum catalyst forms the amorphous carbon layer by heating a mixing solution, acquired by mixing the platinum catalyst supported on the carbon support with the polymer containing carbon and the solvent, under a nitrogen atmosphere until the solvent is dried, raising temperature of the acquired mixing solution to 400 to 900° C. and then maintaining the temperature of the mixing solution.

11 . The method of claim 6 , wherein the amorphous carbon layer is an amorphous carbon layer having a low degree of graphitization.

12 . The method of claim 6 , wherein oxidization of the amorphous carbon layer is carried out by applying a voltage of 1.2 to 1.4 V to the cathode while supplying nitrogen gas and hydrogen gas to the cathode and the anode, respectively.

13 . The method of claim 6 , wherein oxidization of the amorphous carbon layer is carried out by maintaining the membrane electrode assembly for 5 to 20 minutes while supplying nitrogen gas and air to the cathode and the anode, respectively, and extracting a current of 0.1 to 0.2 A/cm 2 from the cathode.

14 . A fuel cell comprising the membrane electrode assembly manufactured by the method of claim 6 .

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Lee Hoon Hui

Classifications

• H01M8/1004 Primary

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

• H01M4/9083

  on carbon or graphite · CPC title

• H01M2004/8689

  Positive electrodes · CPC title

• H01M8/1018

  Polymeric electrolyte materials · CPC title

• H01M4/8825

  Methods for deposition of the catalytic active composition · CPC title