DIRECT OXIDATION FUEL CELL AND PRODUCTION METHOD THEREOF

Abstract

A direct oxidation fuel cell includes at least one unit cell. The at least one unit cell includes: an anode; a cathode; a hydrogen-ion conductive polymer electrolyte membrane interposed between the anode and the cathode; an anode-side separator having a flow channel for supplying and discharging a fuel to and from the anode; and a cathode-side separator having a gas flow channel for supplying and discharging an oxidant gas to and from the cathode. A water-repellent layer is formed on each side of the electrolyte membrane so as to surround the anode or the cathode. When the MEA is hydrated or when a liquid fuel is supplied to the cell for power generation, the part of the electrolyte membrane surrounding the electrodes is prevented from becoming swollen or deformed rapidly. It is therefore possible to ensure adhesion of the electrodes to the electrolyte membrane.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a schematic longitudinal sectional view of a unit cell of a fuel cell in one embodiment of the present invention;

FIG. 2 is an enlarged sectional view of the main part of the unit cell; and

FIG. 3 is a schematic view showing the structure of a spray application apparatus for forming a water-repellent layer on an electrolyte membrane.

Claims

1. A direct oxidation fuel cell comprising at least one unit cell, said at least one unit cell comprising: an anode; a cathode; a hydrogen-ion conductive polymer electrolyte membrane interposed between said anode and said cathode; an anode-side separator having a flow channel for supplying and discharging a fuel to and from said anode; and a cathode-side separator having a gas flow channel for supplying and discharging an oxidant gas to and from said cathode, wherein a water-repellent layer is formed on each side of said electrolyte membrane so as to surround said anode or said cathode.

2. The direct oxidation fuel cell in accordance with claim 1, wherein the contact angle between a surface of said water-repellent layer and water is 130° or more.

3. The direct oxidation fuel cell in accordance with claim 1, wherein said water-repellent layer comprises at least water-repellent resin fine particles and a water-repellent binding material.

4. The direct oxidation fuel cell in accordance with claim 3, wherein said water-repellent resin fine particles are fluorocarbon resin fine particles.

5. The direct oxidation fuel cell in accordance with claim 3, wherein said water-repellent binding material comprises a fluorocarbon resin or a silicone resin.

6. A method for producing a direct oxidation fuel cell, comprising the steps of: forming a catalyst layer that comprises catalyst particles and a polymer electrolyte on each side of an electrolyte membrane to obtain a membrane-catalyst layer assembly;forming a water-repellent layer on said electrolyte membrane so as to surround each of said catalyst layers;immersing the membrane-catalyst layer assembly with the water-repellent layers in water; andbonding a diffusion layer to each of said catalyst layers.

7. The method for producing a direct oxidation fuel cell in accordance with claim 6, wherein said step of forming the water-repellent layer comprises the step of applying a paste for forming the water-repellent layer onto said electrolyte membrane and drying it.

8. The method for producing a direct oxidation fuel cell in accordance with claim 6, wherein said step of forming the water-repellent layer comprises the step of spraying a paste that comprises at least water-repellent resin fine particles and a water-repellent binding material on said electrolyte membrane and drying it.

9. A method for producing a direct oxidation fuel cell, comprising the steps of: forming a water-repellent layer on each side of an electrolyte membrane so as to surround a predetermined area on which a catalyst layer is to be formed;immersing said electrolyte membrane with said water-repellent layers in water;forming a catalyst layer that comprises catalyst particles and a polymer electrolyte on said predetermined area on each side of said electrolyte membrane to obtain a membrane-catalyst layer assembly;immersing the membrane-catalyst layer assembly in water; andbonding a diffusion layer to each of said catalyst layers.

10. The method for producing a direct oxidation fuel cell in accordance with claim 9, wherein said step of forming the water-repellent layer comprises the step of applying a paste for forming the water-repellent layer onto said electrolyte membrane and drying it.

11. The method for producing a direct oxidation fuel cell in accordance with claim 9, wherein said step of forming the water-repellent layer comprises the step of spraying a paste that comprises at least water-repellent resin fine particles and a water-repellent binding material on said electrolyte membrane and drying it.