JP2002280011A - Solid polymer fuel cell and separator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid polymer fuel cell with high efficiency for power generation in a low cost. SOLUTION: This solid polymer fuel cell has a hydrogen electrode on one side of a membrane/electrode joint body 14 and an air electrode on the other side of the membrane/electrode joint body 14, and conductive sheets 17, 18 made from conductive fibers are arranged in a layer where the hydrogen electrode is formed and a layer where the air electrode is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell and a fuel cell separator for generating electricity by sending hydrogen gas or a fuel gas containing hydrogen gas and oxygen or air containing oxygen to the front and back surfaces of a membrane electrode assembly. .

[0002]

2. Description of the Related Art Currently, polymer electrolyte fuel cells are being studied as a core technology of a fuel cell vehicle and a home fuel cell cogeneration system.

FIGS. 12 and 13 show a cell module of a conventional polymer electrolyte fuel cell having a structure in which a solid electrolyte membrane / electrode assembly 1 is sandwiched between separators 2 and 3. FIG. The separators 2 and 3 are important elements because they have a role of supplying hydrogen or oxygen of fuel to the electrodes and a role of flowing generated current. As the separators 2 and 3, a graphite plate was used, and fine grooves 4 and 5 for flowing oxygen and hydrogen were formed in the graphite plate.

[0004]

However, the conventional separators 2 and 3 have small grooves 4 and 5 formed in a graphite plate.
Since it takes time and effort to process, processing cost per sheet is required, and cost reduction has become a major issue. In addition, current does not flow through the gaps between the grooves 4 and 5 of the black smoke plate, so that the current flow path becomes longer and the resistance increases.

The present invention has been made in view of such problems, and has as its object to provide a polymer electrolyte fuel cell which is low in cost and has low resistance during power generation.

[0006]

According to a first aspect of the present invention, there is provided a polymer electrolyte fuel cell, wherein an oxygen electrode is formed on one surface of a membrane-electrode assembly, and In a polymer electrolyte fuel cell in which the membrane / electrode assembly is arranged between a pair of separators so as to form a hydrogen electrode on the other surface side of the assembly, the separator has a gas permeability with a conductive gas seal. A conductive sheet having the conductive gas seal between the oxygen electrode side surface and the membrane electrode assembly, and the conductive gas seal hydrogen electrode side surface and the membrane electrode assembly. It is characterized in that the conductive sheets are arranged between the body and the body.

According to a second aspect of the present invention, in the polymer electrolyte fuel cell according to the first aspect, the conductive sheet is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers. It is characterized by being.

The solid polymer electrolyte fuel cell according to claim 3 is the polymer electrolyte fuel cell according to any one of claims 1 and 2, wherein the conductive sheet of the oxygen electrode and the hydrogen electrode has A slit for diffusing air into each of the conductive sheets is formed.

According to a fourth aspect of the present invention, there is provided the solid polymer electrolyte fuel cell according to any one of the first to third aspects, wherein the conductive gas seal is formed of the membrane / electrode of the conductive sheet. It is characterized by being formed of a conductive film formed on the opposite surface of the joined body.

A fuel cell separator according to a fifth aspect of the present invention is used in a polymer electrolyte fuel cell in which a hydrogen electrode and an oxygen electrode are separated by a membrane / electrode assembly. A fuel cell separator forming a supply space for an oxygen electrode, wherein a conductive gas-permeable sheet in contact with a membrane-electrode assembly is formed on at least one surface of a conductive gas seal.

According to a sixth aspect of the present invention, there is provided the separator for a polymer electrolyte fuel cell according to the fifth aspect, wherein the conductive sheet is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers. It is characterized by being.

According to a seventh aspect of the present invention, in the fuel cell separator according to any one of the fifth and sixth aspects, the conductive sheets of the oxygen electrode and the hydrogen electrode respectively include the hydrogen or oxygen. It has a slit for diffusing in the conductive sheet.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a polymer electrolyte fuel cell according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a sectional configuration of a main part of a polymer electrolyte fuel cell according to this embodiment. In FIG. 1, a polymer electrolyte fuel cell 10 is configured by stacking a number of cells 11 stored in a case (not shown).

The cell 11 which is a structural unit module of the polymer electrolyte fuel cell 10 includes upper and lower separators 12 and 13.
And the membrane / electrode assembly 14, and the separator 1
2, 13 are conductive gas seals 15, 16, respectively;
Conductive sheet 17, 1 made of air-permeable conductive fiber
Consists of eight.

An oxygen electrode for supplying oxygen is provided between the separator 12 and the membrane / electrode assembly 14, and a hydrogen electrode for supplying hydrogen gas is provided between the separator 13 and the membrane / electrode assembly 14. You.

The upper surfaces of the conductive gas seals 15 and 16 of the separators 12 and 13 are used as hydrogen electrodes, and the lower surfaces of the conductive gas seals 15 and 16 are used as oxygen electrodes. Have been.

A film is provided between the conductive gas seals 15 and 16.
The electrode assembly 14 is disposed, the conductive sheet 17 is disposed between the conductive gas seal 15 and the membrane / electrode assembly 14,
A conductive sheet 18 is disposed between the membrane / electrode assembly 14 and the conductive gas seal 16.

The conductive sheet 17 has air permeability so that oxygen serving as an oxygen electrode or air containing oxygen is introduced. The conductive sheet 18 has air permeability so that hydrogen gas serving as a hydrogen electrode or a fuel gas containing hydrogen gas is introduced.

As shown in FIGS. 2 and 3, the membrane / electrode assembly 14 and the conductive gas seals 15 and 16 have an air supply opening 19, an air exhaust opening 20, and a hydrogen supply opening. 21 and a hydrogen exhaust opening 22 are formed.

At the periphery of the air supply opening 19 and the periphery of the air exhaust opening 20 of the conductive gas seal 16,
Flanges 23 and 24 having a height to be in contact with the upper membrane / electrode assembly 14 are provided in a protruding manner. Form.

At the periphery of the hydrogen supply opening 21 of the conductive gas seal 15 and the periphery of the hydrogen exhaust opening 22,
Flanges 25 and 26 each having a height contacting the lower membrane / electrode assembly 14 are protruded, and the flanges 25 and 26 are respectively stacked with the membrane / electrode assembly 14 to provide a hydrogen supply path and a hydrogen exhaust path. Form.

The periphery of the separators 12 and 13 forms a flow space for an oxygen electrode or a flow space for a hydrogen electrode.
Sealed by the sealing material 32.

The conductive sheets 17 and 18 are disposed between the conductive gas seals 15 and 16 and the membrane / electrode assembly 14. In this embodiment, as shown in FIG. 4, the conductive sheets 17 and 18 respectively include three conductive fibers 17A and 1A.
7B, 17C and 18A, 18B, 18C. The conductive sheets 17 and 18 are each made of one cloth sheet, and have openings 19, 20, 21, and 2, respectively.
2 may be cut out.

Of course, a non-woven fabric, a net (mesh), or a fiber bundle may be used instead of the cloth. In this embodiment, carbon fibers are used as the conductive fibers.
A conductive plastic formed in a fibrous form may be used.

Hydrogen electrode conductive sheets 17A, 17B, 1
7C and 18A, 18B, 18C are arranged via a slit 27 extending in a direction intersecting the flow path of oxygen or hydrogen flowing in the oxygen electrode or hydrogen electrode, respectively.

The conductive sheets 17 and 18 may be provided with diffusion openings corresponding to the slits 27 without providing the slits 27 and separating the conductive sheets 17 and 18. The slits 27 prevent unevenness in the flow rate of fuel or air due to the difference in air permeability.

The slit 27 need not be provided as long as there is no fuel or air non-uniformity due to the difference in air permeability.

The membrane / electrode assembly 14 is made of a known material, and includes openings 28, 2 for forming an air supply path, an air exhaust path, a hydrogen supply path, and a hydrogen exhaust path.
9, 30, 31 are formed.

The layer of the conductive sheet 17 sandwiched between the membrane / electrode assembly 14 and the upper conductive gas seal 15 is supplied with oxygen or air containing oxygen. Membrane / electrode assembly 14
Hydrogen or a fuel gas containing hydrogen is supplied to the layer of the cloth conductive sheet 18 sandwiched between the conductive gas seal 16 and the lower conductive gas seal 16.

The polymer electrolyte fuel cell according to this embodiment has a solid state in which a hydrogen electrode is formed on one surface of the membrane-electrode assembly 14 and an oxygen electrode is formed on the other surface of the membrane-electrode assembly 14. In the polymer fuel cell, the air-permeable conductive sheets 17 and 18 made of conductive fibers are disposed on the layer where the hydrogen electrode is formed and the layer where the oxygen electrode is formed, and the membrane-electrode assembly 14 is formed. The conductive gas seals 15 and 16 are the conductive sheet 1
7 and 18, the conductive sheets 17, 1
If the size of the fiber of No. 8 is reduced, the electrical contact interval is reduced. For this reason, when hydrogen gas and oxygen are supplied to the respective poles, the generated current flow path is shortened as shown in FIG. 5, and the resistance loss of the generated power is reduced.

FIGS. 6 to 9 show another embodiment of the separator of the present invention. The separator 40 is used to constitute a polymer electrolyte fuel cell in which a hydrogen electrode and an oxygen electrode are separated by a membrane-electrode assembly. A hydrogen electrode is formed on one surface of the electrode assembly, and an oxygen electrode is formed on the other surface.

FIG. 7 is a sectional view taken along the line AA of the separator 40 of FIG. 6, FIG. 8 is a sectional view taken along the line BB of FIG. 6, and FIG.
FIG. One surface of the conductive gas seal 41 is formed with a gas-permeable conductive sheet 42 that is in contact with the membrane / electrode assembly, as shown in the sectional views of FIGS. In this embodiment, a conductive plastic layer is formed on a conductive sheet 42 to form a conductive gas seal 41. The membrane / electrode assembly 50 shown in FIG. 11 is in contact with the exposed surface S of the conductive sheet 42.

The separator 40 has openings 44 to 47, as shown in FIG.
A conductive plastic layer is formed on the edges 44A and 45A. The plastic layers at the edges 44A and 45A may not have conductivity. The conductive sheet 42 is exposed at the edges of the openings 46 and 47.

As shown in FIG. 10, the separator 40 is formed by previously forming openings 44 to 47 in a large-sized separator sheet material 48, forming a conductive plastic layer, and then cutting it into small pieces. Further, a sealing plastic layer 50 is formed on the outer periphery of the small separator 40 after cutting.

The separator 40 can be used to constitute both the oxygen electrode and the hydrogen electrode by one part. As shown in FIG. The sheets 42, 42 face each other, and the membrane-electrode assembly 49 is placed between the conductive sheets 42, 42.
Is arranged, one cell module 51 for configuring the fuel cell is configured. When a large number of the cell modules 50 are stacked, a fuel cell 52 is formed.

The conductive sheet 42 is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers.
The conductive sheet 42 may include an elongated slit extending in the same direction as the slit 27 in order to diffuse hydrogen or oxygen into each conductive sheet 42.

According to the separator 40 shown in FIGS. 6 to 9, since the conductive gas seal 41 is formed on one surface of the air-permeable conductive sheet 42 in contact with the membrane / electrode assembly, the sheet material 48 of the separator 40 is formed. The fuel cell 52 can be formed easily by cutting it after forming it in a large size, and by easily stacking the fuel cell 52 as shown in FIG. And
Since the conductive sheet 42 of the separator 40 is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers, the production is also easy and the cost is low.
Furthermore, when the separator 40 is formed with slits for diffusing hydrogen or oxygen into the respective conductive sheets 42 of the oxygen electrode and the hydrogen electrode, diffusion of hydrogen or oxygen is improved, and uniform current density is obtained. It is advantageous to obtain

[0039]

According to the polymer electrolyte fuel cell of the present invention, the separator is constituted by a conductive gas seal and a conductive sheet having air permeability, and the oxygen of the conductive gas seal is reduced. Since the conductive sheet was disposed between the electrode side surface and the membrane / electrode assembly, and between the hydrogen electrode side surface of the conductive gas seal and the membrane / electrode assembly, The current path becomes shorter, the resistance decreases, and the output voltage increases. In addition, since it is made of a conductive sheet having air permeability without using a graphite plate, the production is easy and the cost is low, and the cost of the fuel cell can be reduced. Furthermore, with respect to the generated water on the oxygen electrode side, by subjecting the conductive sheet to a treatment for increasing the hydrophilicity, the generated water can be efficiently removed from the electrode surface, and the reaction inhibition of the battery can be prevented as much as possible.

According to the second aspect of the present invention, the conductive sheet is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers. As a result, the current flows into the entirety of the conductive fibers, so that the current density has less unevenness and the electric resistance can be reduced.

According to a third aspect of the present invention, in the polymer electrolyte fuel cell according to any one of the first and second aspects, the hydrogen or air is applied to the conductive sheets of the oxygen electrode and the hydrogen electrode. Since slits for diffusing in each conductive sheet are formed, even if there is a difference in air permeability, unevenness of hydrogen gas or oxygen can be reduced, and a decrease in electromotive force can be prevented.

According to a fourth aspect of the present invention, in the polymer electrolyte fuel cell according to any one of the first to third aspects, the conductive gas seal is formed of the membrane-electrode assembly of the conductive sheet. Since the conductive film is formed on the opposite surface, the manufacturing cost is reduced.

In the fuel cell separator according to the invention of claim 5 of the present application, a gas-permeable conductive sheet that is in contact with the membrane-electrode assembly is formed on at least one surface of the conductive gas seal. After a large material is formed, it can be cut into large pieces and easily manufactured in large quantities, and a fuel cell can be formed by stacking.

In the fuel cell separator according to the invention of claim 6 of the present application, since the conductive sheet is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers, it is also easy to manufacture. , Low cost.

In the fuel cell separator according to the seventh aspect of the present invention, each of the conductive sheets for the oxygen electrode and the hydrogen electrode has a slit for diffusing the hydrogen or oxygen into each conductive sheet. Diffusion is good,
This is advantageous for obtaining a uniform current density.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main structure of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a cross-sectional configuration on an air supply port and a hydrogen gas supply port side in the stacked cell of FIG. 1;

FIG. 3 is a schematic diagram of a cross-sectional configuration on an air exhaust port and a hydrogen gas exhaust port side in the stacked cell of FIG. 1;

FIG. 4 is a plan view of the separator shown in FIG. 1;

FIG. 5 is a schematic diagram of a current flowing from the membrane-electrode assembly to the air electrode side.

FIG. 6 is a plan view of a fuel cell separator according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view of the separator 40 of FIG. 6 taken along the line AA.

FIG. 8 is a sectional view taken along the line BB of FIG. 6;

FIG. 9 is a sectional view taken along the line CC in FIG. 6;

FIG. 10 is a plan view of a sheet material serving as a material of the fuel cell separator of FIG. 6;

11 is an explanatory view of a fuel cell in which the separator of FIG. 6 is stacked.

FIG. 12 is an exploded view showing a configuration of a cell of a polymer electrolyte fuel cell using a conventional graphite plate separator.

FIG. 13 is an explanatory view showing a current flow path flowing through a conventional graphite plate separator.

[Explanation of symbols]

 Reference Signs List 10 polymer electrolyte fuel cell 11 cell 12, 13 separator 14 membrane / electrode assembly 15, 16 conductive gas seal 17, 18 conductive sheet 19 air supply opening 20 air exhaust opening 21 hydrogen supply opening 22 Hydrogen exhaust opening 27 Slit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenji Sugimoto 2109-8 Yashima Nishimachi, Takamatsu City, Kagawa Prefecture F-term in Shikoku Research Institute, Inc. (reference) 5H026 AA06 CC03 CX02 CX03 CX05

Claims (7)

[Claims] 1. A method according to claim 1, wherein an oxygen electrode is formed on one surface of the membrane-electrode assembly, and a hydrogen electrode is formed on the other surface of the membrane-electrode assembly. In the polymer electrolyte fuel cell in which the electrode assembly is arranged, the separator is constituted by a conductive gas seal and a conductive sheet having air permeability, and the surface of the conductive gas seal on the oxygen electrode side and the membrane Wherein the conductive sheets are disposed between the electrode assembly and between the hydrogen electrode side surface of the conductive gas seal and the membrane / electrode assembly, respectively. battery. 2. The polymer electrolyte fuel cell according to claim 1, wherein the conductive sheet is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers. Shaped fuel cell. 3. The polymer electrolyte fuel cell according to claim 1, wherein the hydrogen or air is diffused into the conductive sheets of the oxygen electrode and the hydrogen electrode, respectively. A polymer electrolyte fuel cell, characterized in that a slit is formed to cause the slit to be formed. 4. The polymer electrolyte fuel cell according to claim 1, wherein the conductive gas seal is provided on the membrane of the conductive sheet.
A polymer electrolyte fuel cell, comprising a conductive film formed on a surface opposite to the electrode assembly. 5. A polymer electrolyte fuel cell wherein a hydrogen electrode and an oxygen electrode are separated by a membrane-electrode assembly.
A fuel cell separator that forms a supply space for the hydrogen electrode and the oxygen electrode together with an electrode assembly, and a gas-permeable conductive sheet that is in contact with the membrane-electrode assembly is formed on at least one surface of a conductive gas seal. A fuel cell separator characterized by the above-mentioned. 6. The fuel cell according to claim 5, wherein the conductive sheet is at least one of a cloth, a nonwoven fabric, a net, and a fiber bundle made of conductive fibers. Battery separator. 7. The fuel cell separator according to claim 5, wherein each of the conductive sheets of the oxygen electrode and the hydrogen electrode has a slit for diffusing the hydrogen or oxygen into each of the conductive sheets. A fuel cell separator comprising: