Device and method for evaluating performance of fuel cells, device and method for evaluating specific surface area of fuel-cell electrode catalysts, fuel-cell electrode catalyst, and method of manufacturing the same

• US 20040161850A1
• Filed: 02/17/2004
• Published: 08/19/2004
• Est. Priority Date: 02/02/2000
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kawahara, Tatsuya, Kato, Hisao, Ozaki, Toshiaki
• Granted Patent: US 6,921,604 B2
• Time in Patent Office: Days
• US Class Current: 436/37
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 4/92 Metals of platinum group H01M4/94 , H01M4/9058 take precedence
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: H01M 8/04 Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49108 Electric battery cell making

Abstract

A device and a method for simply and accurately evaluating-performance of fuel cells have been provided. Hydrogen gas and carbon monoxide gas are caused to flow into a sample holder where an electrode catalyst sample is laid, and the amount of carbon monoxide gas discharged therefrom is detected. The amount of carbon monoxide gas adsorbed by the electrode catalyst sample is calculated based on the amount of supplied carbon monoxide gas and the amount of detected carbon monoxide gas. The output voltage of a fuel cell is calculated based on a correlation between calculated amounts of carbon monoxide gas adsorbed by the electrode catalyst and output voltages of the fuel cell.

Claims

1. A device for evaluating performance of fuel cells, comprising:

a container that holds an electrode catalyst used in a fuel cell;

a supplier communicating with the container that supplies a predetermined amount of carbon monoxide to the container;

a detector communicating with the container that detects an amount of carbon monoxide discharged from the container;

an adsorption amount determiner that determines an amount of carbon monoxide adsorbed by the electrode catalyst based on the amount of carbon monoxide supplied by the supplier and the amount of carbon monoxide detected by the detector; and

a calculator that calculates an output voltage of the fuel cell based on the determined adsorption amount.

2. The device according to claim 1, wherein the calculator determines the output voltage based on a correlation between adsorption amounts of carbon monoxide and output voltages of the fuel cell, the correlation being established through specific surface areas of the electrode catalyst.

3. The device according to claim 2, further comprising:

a reducing agent supplier communicating with the container that supplies a reducing agent, which reduces the electrode catalyst within an operating temperature range of the fuel cell, to the container before the supplier starts supplying carbon monoxide.

4. A device for evaluating specific surface area of electrode catalysts for fuel cells, comprising:

a container that holds an electrode catalyst used in a fuel cell;

a reducing agent supplier communicating with the container that supplies a reducing agent, which reduces the electrode catalyst within an operating temperature range of the fuel cell, to the container;

a carbon monoxide supplier communicating with the container that supplies a predetermined amount of carbon monoxide to the container after reduction has been carried out by the reducing agent;

a detector communicating with the container that detects an amount of carbon monoxide discharged from the container;

an adsorption amount determiner that determines an amount of carbon monoxide adsorbed by the electrode catalyst based on the amount of carbon monoxide supplied by the supplier and the amount of carbon monoxide detected by the detector; and

a calculator that calculates a specific surface area of the electrode catalyst based on the determined adsorption amount.

5. The device according to claim 4, wherein the reducing agent is hydrogen and reduces the electrode catalyst within a temperature range of 60°

C. to 150°

C.

6. A method for evaluating performance of fuel cells, comprising:

supplying carbon monoxide to a container holding an electrode catalyst used in a fuel cell;

determining an amount of carbon monoxide adsorbed by the electrode catalyst; and

calculating an output voltage of the fuel cell based on the calculated adsorption amount.

7. The method according to claim 6, further comprising:

supplying hydrogen gas to the container prior to the supply of the carbon monoxide; and

reducing the electrode catalyst within an operating temperature range of the fuel cell by means of the hydrogen gas.

8. A method for evaluating specific surface area of electrode catalysts for fuel cells, comprising:

supplying hydrogen gas to a container holding an electrode catalyst used in a fuel cell;

reducing the electrode catalyst within an operating temperature range of the fuel cell by means of the hydrogen gas;

supplying carbon monoxide to the container after the reduction has been completed;

determining an amount of carbon monoxide adsorbed by the electrode catalyst; and

calculating a specific surface area of the electrode catalyst based on the determined adsorption amount.

9. The method according to claim 8, wherein the reducing agent is within a temperature range of 60°

C. to 150°

C.

10. A method for manufacturing electrode catalysts for fuel cells, comprising:

preparing a carbon carrier having a specific surface area of 1000 m²/g or more; and

having platinum carried on the carbon carrier with a predetermined platinum-carrying density.

11. The method according to claim 10, wherein the platinum-carrying density is 70 weight % after the carbon carrier has the platinum carried thereon.

12. The method according to claim 11, further comprising:

reducing the electrode catalyst in its liquid phase using a reducing agent selected from a group comprising sodium tetrahydroborate, formic acid and hydrazine.

13. A method for manufacturing membrane-electrode assemblies, comprising:

forming an electrode catalyst by having platinum carried on a carbon carrier having a specific surface area of 1000 m²/g or more with a predetermined platinum-carrying density; and

fixing the electrode catalyst onto an electrolytic membrane.

14. A method for manufacturing unit cells constituting fuel cells, comprising:

forming an electrode catalyst by having platinum carried on a carbon carrier having a specific surface area of 1000 m²/g or more with a predetermined platinum-carrying density;

forming an electrode from the electrode catalyst; and

assembling the electrode with an electrolytic membrane and separators.

15. The method according to claim 14, wherein the platinum-carrying density is 70 weight % after the carbon carrier has the platinum carried thereon.

16. A method for manufacturing fuel cells, comprising:

forming an electrode catalyst by having platinum carried on a carbon carrier having a specific surface area of 1000 m²/g or more with a predetermined platinum-carrying density;

forming an electrode from the electrode catalyst;

forming a unit cell by assembling the electrode with an electrolytic membrane and separators;

stacking a plurality of unit cells formed in the preceding step; and

arranging current collecting plates at opposed ends of the stacked unit cells and fixing the current collecting plates.

17. An electrode catalyst used for fuel cells, comprising:

a carbon carrier having a specific surface area of 1000 m²/g or more; and

platinum carried on the carbon carrier with a predetermined platinum-carrying density.

18. The electrode catalyst according to claim 17, wherein the platinum-carrying density is 70 weight % after the carbon carrier has the platinum carried thereon.

19. A membrane-electrode assembly for fuel cells, comprising:

an electrode catalyst composed of platinum carried on a carbon carrier having a specific surface area of 1000 m²/g or more with a predetermined platinum-carrying density; and

an electrolytic membrane to which the electrode catalyst is fixed.

20. A unit cell constituting a fuel cell, comprising:

electrodes having an electrode catalyst having platinum carried on a carbon carrier having a specific surface area of 1000 m²/g or more with a predetermined platinum-carrying density;

an electrolytic membrane whose front and back surfaces have the electrodes disposed thereon; and

separators disposed on front and back sides of the electrolytic membrane.

21. The unit cell according to claim 20, wherein the platinum-carrying density is 70 weight % after the carbon carrier has the platinum carried thereon.

22. A fuel cell comprising:

electrodes having an electrode catalyst having platinum carried on a carbon carrier having a specific surface area of 1000 m²/g or more with a predetermined platinum-carrying density;

an electrolytic membrane whose front and back surfaces have the electrodes disposed thereon;

separators disposed on front and back sides of the electrolytic membrane;

a stack formed by stacking a plurality of the separators; and

current collecting plates disposed at opposed ends of the stack.

23. A method for evaluating gaseous-reaction electrodes, comprising:

exposing a gaseous-reaction electrode to a carbon monoxide atmosphere;

determining an amount of carbon monoxide adsorbed by the gaseous-reaction electrode; and

evaluating performance of the gaseous-reaction electrode based on the amount of the adsorbed carbon monoxide.