WO2011007518A1

WO2011007518A1 - Membrane-electrode assembly, solid polymer fuel cell, and fuel cell power generation system

Info

Publication number: WO2011007518A1
Application number: PCT/JP2010/004375
Authority: WO
Inventors: 菅原靖; 鵜木重幸; 小足直嗣
Original assignee: パナソニック株式会社
Priority date: 2009-07-14
Filing date: 2010-07-05
Publication date: 2011-01-20

Abstract

Disclosed is a membrane-electrode assembly provided with an anode (5B), a cathode (5A), a polymer electrolyte membrane (1), and either a first carbon layer (2A) disposed between either an anode catalyst layer (3B) and/or a cathode catalyst layer (3A) and the polymer electrolyte membrane (1) and/or a second carbon layer (2B) disposed either between the anode catalyst layer (3B) and an anode gas diffusion layer (4B) and/or between the cathode catalyst layer (3A) and a cathode gas diffusion layer (4A), wherein the carbon layer is configured such that the ionization tendency of carbon in the carbon layer is larger than the ionization tendency of catalyst-supported carbon in either the anode catalyst layer (3B) and/or the cathode catalyst layer (3A) and the amount of supported catalyst in the carbon layer is smaller than the amount of supported catalyst in either the anode catalyst layer (3B) and/or the cathode catalyst layer (3A).

Description

Membrane-electrode assembly, polymer electrolyte fuel cell, and fuel cell power generation system

The present invention relates to a membrane-electrode assembly, a polymer electrolyte fuel cell, and a fuel cell power generation system, and more particularly to a structure of a membrane-electrode assembly.

A polymer electrolyte fuel cell (hereinafter referred to as PEFC) is an electric cell that reacts electrochemically with a fuel gas containing hydrogen obtained by reforming a raw material gas such as city gas and an oxidant gas containing oxygen such as air. And generate heat at the same time. At this time, the reaction shown in the chemical reaction formula (1) occurs at the anode, and the reaction shown in the chemical reaction formula (2) occurs at the cathode.

2H ₂ → 4H ⁺ + 4e ⁻ (1)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)
By the way, it is known that when the fuel cell is started from the state where air exists in both the anode and the cathode, a deterioration reaction of the catalyst-supporting carrier occurs (for example, see Non-Patent Document 1). When starting the fuel cell from a state where air is present in both the anode and the cathode, at the beginning of supplying hydrogen to the gas flow path of the anode, there is no region where hydrogen exists in the fuel gas flow path. A region is formed. Thereby, also in the anode, a region where hydrogen exists and a region where hydrogen does not exist are formed. And in the area | region which opposes the area | region where the hydrogen of the anode of a cathode does not exist, the deterioration reaction of a catalyst carrying | support carrier arises. For example, when carbon is used as the catalyst support, the reaction shown in chemical reaction formula (3) occurs.

C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻ (3)
As a result, the carbon carrier carrying the catalyst such as Pt is corroded, the cathode electrode catalyst is greatly deteriorated, and the performance of the fuel cell is lowered. In the region where the anode air is present, the reaction shown in the chemical reaction formula (4) occurs and water is generated.

O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (4)
In order to prevent cathode deterioration due to such a phenomenon, a corroded region composed of carbon that is more easily oxidized than the support carbon of the catalyst layer is formed on the separator channel wall surface, the region along the outer edge of the catalyst layer, or the outer edge of the catalyst layer. A fuel cell is known that is arranged in a lattice pattern when viewed from the region along the thickness direction of the catalyst layer. (For example, refer to Patent Document 1). In the fuel cell disclosed in Patent Document 1, the corrosion region is more easily oxidized than the catalyst layer, so that deterioration of the fuel cell due to oxidation of the catalyst layer can be suppressed.

In addition, a solid polymer fuel cell is known that has a water retention layer composed of carbon and ionomer between a catalyst layer and a polymer electrolyte membrane for the purpose of improving the performance of water retention (for example, Patent Documents). 2).

JP 2006-236631 A JP 2007-188768 A

However, in the fuel cell disclosed in Patent Document 1, when the corroded region is formed on the separator channel wall surface, the proton conductivity is long, and therefore the proton conductivity is low. If it is configured in a grid or a region along the outer edge of the catalyst layer,
There is a problem that the region where air is present in the anode at the start-up or the region where hydrogen is deficient in the anode during power generation does not coincide with the corrosion region, and the corrosion region does not function sufficiently.

In the polymer electrolyte fuel cell disclosed in Patent Document 2, since the ionomer / carbon water retention layer having a high ionomer ratio is disposed between the catalyst layer and the polymer electrolyte membrane, the water retention layer is the catalyst layer. It can be oxidized before the degradation of the performance of the fuel cell due to oxidation of the catalyst layer. However, protons are sufficiently conducted between the membrane and catalyst layers, and protons are sufficiently conducted between the catalyst layers (between the catalyst layers). In order to suppress a decrease in proton conductivity, the ionomer / carbon mass ratio (I / C) of the water retention layer disposed between the catalyst layer and the polymer electrolyte membrane is low, so that the initial voltage decreases. There was a problem.

The present invention solves the above-described conventional problems, improves the durability of the catalyst layer against oxidative corrosion reaction, and can suppress the decrease in the initial voltage, the membrane-electrode assembly, and the polymer electrolyte fuel An object is to provide a battery and a fuel cell power generation system.

In order to solve the above problems, a membrane-electrode assembly according to the present invention comprises an anode having a catalyst-carrying carbon and an ionomer and an anode gas diffusion layer, and a cathode catalyst comprising the catalyst-carrying carbon and the ionomer. A cathode having a layer and a cathode gas diffusion layer; a polymer electrolyte membrane disposed between the anode catalyst layer and the cathode catalyst layer; at least one of the anode catalyst layer and the cathode catalyst layer; and the polymer electrolyte. And a first carbon layer having carbon and an ionomer, and disposed between at least one of the anode catalyst layer and the anode gas diffusion layer and between the cathode catalyst layer and the cathode gas diffusion layer. And at least one carbon layer of a second carbon layer having carbon and an ionomer. In the first carbon layer and the second carbon layer, the ionization tendency of carbon in the first carbon layer and the second carbon layer is an ionization tendency of at least one catalyst-supporting carbon in the anode catalyst layer and the cathode catalyst layer. The catalyst loading amount of the first carbon layer and the second carbon layer is configured to be smaller than the catalyst loading amount of at least one of the anode catalyst layer and the cathode catalyst layer. .

As a result, when the first carbon layer is provided, electrons and protons are easily transferred between at least one of the anode catalyst layer and the cathode catalyst layer in the first carbon layer, and the initial voltage is increased. Can be sufficiently suppressed. Further, when the second carbon layer is included, the second carbon layer has proton conductivity and sufficient gas diffusibility from the gas diffusion layer to the catalyst layer. The decrease can be sufficiently suppressed. Furthermore, since carbon in the carbon layer is more easily oxidized than carrier carbon in the catalyst layer, it is possible to suppress deterioration of battery characteristics due to oxidative corrosion of the catalyst layer and to improve durability.

In the membrane-electrode assembly according to the present invention, the first carbon layer and the second carbon layer may be composed of carbon and ionomer not supporting a catalyst.

In the membrane-electrode assembly according to the present invention, the ionomer / carbon mass ratio (I / C) of the first carbon layer may be 1.3 or more and 2.0 or less.

In the membrane-electrode assembly according to the present invention, the ionomer / carbon mass ratio (I / C) of the second carbon layer may be 0.6 or more and 1.3 or less.

In the membrane-electrode assembly according to the present invention, the EW of the ionomer of the first carbon layer and the second carbon layer may be 700 or more and 1100 or less.

The polymer electrolyte fuel cell according to the present invention comprises the membrane-electrode assembly, and a pair of conductive separators arranged in a plate shape so as to sandwich the membrane-electrode assembly. Prepare.

The fuel cell power generation system according to the present invention includes the solid polymer fuel cell, a fuel gas supply device that supplies fuel gas to the anode via a fuel gas supply channel, and an oxidant gas supply channel to the cathode. An oxidant gas supply device for supplying an oxidant gas via the gas, an off-fuel gas passage through which a fuel gas not used in the anode flows, a purge air supply device, and a controller. In the fuel cell power generation system, the controller controls the purge air supply so that air is supplied to the anode for purging when the fuel cell power generation system is stopped.

Further, in the fuel cell power generation system according to the present invention, the purge air supply device is configured to supply the oxidant gas to the anode from the oxidant gas supply device and the oxidant gas supply device. It may be composed of roads.

Further, in the fuel cell power generation system according to the present invention, the purge air supply is connected to the fuel gas supply path or the off-fuel gas flow path, and the atmospheric open flow path having the open air end and the open air flow path And an on-off valve provided in the.

Furthermore, in the fuel cell power generation system according to the present invention, the controller may be configured to perform startup processing of the fuel cell power generation system from a standby state in which air is present at the anode and the cathode.

The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.

According to the membrane-electrode assembly, the polymer electrolyte fuel cell, and the fuel cell power generation system of the present invention, it is possible to suppress the deterioration of the battery characteristics due to the oxidative corrosion of the carbon support in the catalyst layer and to improve the durability. It becomes. Further, by improving the durability of the catalyst layer, the control of the fuel cell power generation system can be simplified, and the system can be simplified and the cost can be reduced.

FIG. 1 is a cross-sectional view schematically showing a schematic configuration of the membrane-electrode assembly according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view schematically showing a schematic configuration and operation of a polymer electrolyte fuel cell (solid polymer electrolyte fuel cell according to Embodiment 1 of the present invention) including the membrane-electrode assembly shown in FIG. FIG. FIG. 3 is a cross-sectional view schematically showing the operation of the polymer electrolyte fuel cell (solid polymer electrolyte fuel cell according to Embodiment 1) including the membrane-electrode assembly shown in FIG. . FIG. 4 is a cross-sectional view schematically showing a schematic configuration and operation of a polymer electrolyte fuel cell according to Embodiment 2 of the present invention. FIG. 5 is a cross-sectional view schematically showing a schematic configuration of the polymer electrolyte fuel cell according to Embodiment 3 of the present invention. FIG. 6 is a cross-sectional view schematically showing a schematic configuration of the membrane-electrode assembly according to Embodiment 4 of the present invention. FIG. 7 is a cross-sectional view schematically showing a schematic configuration and operation of a polymer electrolyte fuel cell including the membrane-electrode assembly shown in FIG. FIG. 8 is a cross-sectional view schematically showing the operation of the polymer electrolyte fuel cell comprising the membrane-electrode assembly shown in FIG. FIG. 9 is a cross-sectional view schematically showing a schematic configuration and operation of a polymer electrolyte fuel cell according to Embodiment 5 of the present invention. FIG. 10 is a cross-sectional view schematically showing a schematic configuration of the polymer electrolyte fuel cell according to Embodiment 6 of the present invention. FIG. 11 is a cross-sectional view schematically showing a schematic configuration of a polymer electrolyte fuel cell according to Embodiment 7 of the present invention. FIG. 12 is a schematic diagram showing a schematic configuration of a fuel cell power generation system according to Embodiment 8 of the present invention. FIG. 13 is a schematic diagram showing a schematic configuration of a fuel cell power generation system according to Embodiment 9 of the present invention. FIG. 14 is a schematic diagram showing a schematic configuration of the fuel cell power generation system according to Embodiment 10 of the present invention. FIG. 15 is a table showing the voltage and deterioration rate of each polymer electrolyte fuel cell before and after the performance evaluation test. FIG. 16 is a table showing the voltage and deterioration rate of each polymer electrolyte fuel cell before and after the performance evaluation test.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, in all the drawings, only components necessary for explaining the present invention are extracted and illustrated, and other components are not illustrated. Furthermore, the present invention is not limited to the following embodiment.

(Embodiment 1)
Embodiment 1 of the present invention exemplifies a form in which a first carbon layer having carbon and ionomer is disposed between a polymer electrolyte membrane and a cathode catalyst layer.
[Configuration of membrane-electrode assembly and polymer electrolyte fuel cell including the same]
First, regarding the configuration of the membrane-electrode assembly according to Embodiment 1 of the present invention and the polymer electrolyte fuel cell including the membrane-electrode assembly (solid polymer fuel cell according to Embodiment 1 of the present invention), FIG. This will be described with reference to FIG.

FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a membrane-electrode assembly according to Embodiment 1 of the present invention. FIG. 2 schematically shows the schematic configuration and operation of the polymer electrolyte fuel cell (solid polymer fuel cell according to Embodiment 1) of the present invention provided with the membrane-electrode assembly shown in FIG. It is sectional drawing, and shows a state when gas, such as fuel gas which exists in an anode, is purged with air when a polymer electrolyte fuel cell is stopped.

As shown in FIG. 1, a membrane-electrode assembly 11 according to the first embodiment includes a cathode 5A having a polymer electrolyte membrane 1, a first carbon layer 2A, a cathode catalyst layer 3A, and a cathode gas diffusion layer 4A. And an anode 5B having an anode catalyst layer 3B and an anode gas diffusion layer 4B. The polymer electrolyte membrane 1 is configured to selectively transport hydrogen, and the first carbon layer 2A is provided on one main surface of the polymer electrolyte membrane 1, and the other main surface. Is provided with an anode catalyst layer 3B. A cathode catalyst layer 3A is provided on the main surface of the first carbon layer 2A on the side not in contact with the polymer electrolyte membrane 1. In addition, manifold holes such as a fuel gas supply manifold hole including through holes in the thickness direction are provided in the peripheral edge portion of the main surface of the polymer electrolyte membrane 1 (not shown).

The configuration of the anode catalyst layer 3B and the cathode catalyst layer 3A is not particularly limited as long as the anode catalyst layer 3B and the cathode catalyst layer 3A have catalyst-supporting carbon and ionomer, respectively, and the configurations of the anode catalyst layer 3B and the cathode catalyst layer 3A are the same. May be different or different. For example, a catalyst-supporting carbon made of carbon powder (conductive carbon particles) supporting an electrode catalyst and an ionomer (for example, a polymer electrolyte) attached to the catalyst-supporting carbon further include a water-repellent material such as polytetrafluoroethylene. It may be a configuration.

On the other hand, the first carbon layer 2A has carbon and ionomer. The carbon used in the first carbon layer 2A is configured such that its ionization tendency is larger than the ionization tendency of carbon used in at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A. Specifically, the carbon used in the catalyst layer is calcined to reduce the surface functional groups that serve as oxidation starting points, or the specific surface area of the carbon used in the first carbon layer 2A is reduced. By using carbon larger than the carbon used for the catalyst layer, the ionization tendency of the carbon used for the first carbon layer 2A can be relatively increased.

As a result, the carbon used in the first carbon layer 2A is more easily oxidized than the catalyst-carrying carbon (carrier carbon) of the catalyst layer. Can do.

Further, in the first carbon layer 2A, the amount of the catalyst supported on the first carbon layer 2A is at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A (in the first embodiment, the anode catalyst layer 3B and the cathode catalyst layer 3A). Both) is configured to be smaller than the amount of catalyst supported. Thereby, it can suppress that it melt | dissolves by corrosion of carbon, precipitates in the polymer electrolyte membrane 1, and accelerates the film degradation of the polymer electrolyte membrane 1.

In addition, from the viewpoint of suppressing the catalyst contained in the first carbon layer 2A from being dissolved due to the corrosion of carbon and precipitating in the polymer electrolyte membrane 1, the amount of catalyst supported on the first carbon layer 2A is as small as possible. Preferably, the first carbon layer 2A is more preferably configured not to carry a catalyst. That is, the first carbon layer 2A is preferably composed of carbon and ionomer that do not carry a catalyst. In this case, the first carbon layer 2A does not exclude the inclusion of substances other than carbon and ionomer that do not carry a catalyst.

In the first embodiment, the catalyst loading amount of the first carbon layer 2A is configured to be smaller than the catalyst loading amounts of both the anode catalyst layer 3B and the cathode catalyst layer 3A. However, the present invention is not limited to this. The first carbon layer only needs to be configured to be smaller than the amount of catalyst supported on at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A, and more than the amount of catalyst supported on the catalyst layer in contact with the first carbon layer 2A. You may be comprised so that the catalyst load of 2A may become small.

Also, the first carbon layer 2A is configured such that the ionomer / carbon mass ratio (I / C) of the first carbon layer 2A is 1.3 or more from the viewpoint of maintaining proton conductivity and normal power generation performance. In view of maintaining electronic conductivity, it is preferable that I / C is 2.0 or less. Furthermore, from the same viewpoint, it is more preferable that the I / C is configured to be 1.9 or less. As a result, the first carbon layer 2A can easily move electrons and protons between the cathode catalyst layer 3A and sufficiently suppress the decrease in the initial voltage.

Further, the first carbon layer 2A preferably has an EW of 700 or more from the viewpoint of maintaining the shape stability of the first carbon layer 2A, and from the viewpoint of maintaining the performance of the first carbon layer 2A. The EW is preferably 1100 or less. As a result, it is possible to improve the proton conductivity while ensuring the electron transfer property, the carbon contained in the first carbon layer 2A is more selectively oxidized and corroded, and the oxidation corrosion of the cathode catalyst layer 3A is prevented. It can suppress more effectively.

As shown in FIG. 2, the polymer electrolyte fuel cell (single cell) 20 according to the first embodiment includes a membrane-electrode assembly 11, a pair of

gaskets

6A and 6B, and a pair of conductive materials.

Separators

7A and 7B (cathode separator 7A and anode separator 7B).

The gasket 6A is provided around the first carbon layer 2A and the cathode 5A, and the gasket 6B is provided around the anode 5B. In addition, the

gaskets

6A and 6B are formed in a donut shape here. It is made of fluoro rubber. As a result, the fuel gas and the oxidant gas are suppressed from leaking out of the polymer electrolyte fuel cell 20, and the gas is suppressed from being mixed with each other in the polymer electrolyte fuel cell 20. The Note that manifold holes (not shown) such as fuel gas supply manifold holes each having a through hole in the thickness direction are provided in the peripheral portions of the

gaskets

6A and 6B.

The cathode separator 7A is provided so as to sandwich the membrane-electrode assembly 11 and the gasket 6A, and the anode separator 7B is provided so as to sandwich the membrane-electrode assembly 11 and the gasket 6A. Thereby, the membrane-electrode assembly 11 is mechanically fixed, and when the plurality of polymer electrolyte fuel cells 20 are stacked in the thickness direction, the membrane-electrode assembly 11 is electrically connected. In addition, these

separators

7A and 7B can use the metal excellent in heat conductivity and electroconductivity, graphite, or what mixed graphite and resin, for example, carbon powder and a binder (solvent). A mixture prepared by injection molding or a plate of titanium or stainless steel plated with gold can be used.

On one main surface (hereinafter referred to as an inner surface) of the cathode separator 7A that is in contact with the cathode 5A, there is provided a groove-like oxidant gas flow path 8 for allowing the oxidant gas to flow therethrough. The main surface (hereinafter referred to as the outer surface) is provided with a groove-like cooling medium flow path 10 through which the cooling medium flows. Similarly, on one main surface (hereinafter referred to as an inner surface) of the anode separator 7B that is in contact with the anode 5B, there is provided a groove-like fuel gas flow path 9 through which the fuel gas flows. The main surface (hereinafter referred to as the outer surface) is provided with a groove-like cooling medium flow path 10 through which the cooling medium flows.

Thus, fuel gas and oxidant gas are supplied to the anode 5B and the cathode 5A, respectively, and these gases react to generate electricity and heat. Further, the generated heat is recovered by passing a cooling medium such as cooling water through the cooling medium flow path 10.

Then, by stacking the polymer electrolyte fuel cells 20 according to the first embodiment configured in this way in the thickness direction, a cell stack is formed (not shown). At this time, each manifold hole such as a fuel gas supply manifold hole provided in the polymer electrolyte membrane 1, the

gaskets

6A and 6B, the cathode separator 7A, and the anode separator 7B is formed when the polymer electrolyte fuel cells 20 are stacked. Respective manifolds such as fuel gas supply manifolds are formed in the thickness direction. Then, a current collector plate and an insulating plate are arranged at both ends of the cell stack, a pair of end plates are further arranged at both ends, and fastened with a fastener to form a fuel cell stack (not shown). )

[Effects of membrane-electrode assembly and polymer electrolyte fuel cell including the same]
Next, referring to FIG. 1 to FIG. 3, the membrane-electrode assembly 11 according to the first embodiment and the polymer electrolyte fuel cell having the same (the polymer electrolyte fuel cell according to the first embodiment) ) 20 effects will be described.

FIG. 3 is a cross-sectional view schematically showing the operation of the polymer electrolyte fuel cell (solid polymer fuel cell according to Embodiment 1) 20 including the membrane-electrode assembly 11 shown in FIG. A state when starting of the polymer electrolyte fuel cell 20 is started from a state in which air exists in the anode 5B and the cathode 5A.

As shown in FIG. 2, when the solid polymer fuel cell 20 is stopped, air is supplied to the anode 5B via a fuel gas supply manifold (not shown) and the fuel gas flow path 9, When the fuel gas or the like existing in the anode 5B (including the fuel gas supply manifold and the fuel gas channel 9) is purged with air, a region where hydrogen exists and a region where hydrogen does not exist are formed in the fuel gas channel 9.

Further, as shown in FIG. 3, from a standby state where air is present in the anode 5B and the cathode 5A of the polymer electrolyte fuel cell 20, through a fuel gas supply manifold (not shown) and the fuel gas passage 9, The fuel gas is supplied to the anode 5B, and the oxidant gas is supplied to the cathode 5A via the oxidant gas supply manifold (not shown) and the oxidant gas flow path 8 (starting process of the polymer electrolyte fuel cell 20) ), A region where hydrogen exists and a region where hydrogen does not exist are formed in the fuel gas passage 9.

Then, when a region where hydrogen exists and a region where hydrogen does not exist are formed in the fuel gas flow path 9, a region where hydrogen exists and a region where hydrogen does not exist are also formed in the anode 5B. At this time, as shown in FIGS. 2 and 3, in the region where hydrogen exists in the anode 5B (more precisely, the anode catalyst layer 3B), the reaction of the chemical reaction formula (1) described above occurs, and the cathode 5A ( Precisely, the reaction of the chemical reaction formula (2) described above occurs in a region of the cathode catalyst layer 3A) opposite to the region where the hydrogen of the anode 5B exists.

On the other hand, in the cathode 5A (more precisely, the cathode catalyst layer 3A) in the region facing the region where the hydrogen of the anode 5B does not exist, the reaction of the above-described chemical reaction formula (3) is performed in the conventional polymer electrolyte fuel cell. Occurs. Further, in the region where no hydrogen exists in the anode 5B (more precisely, the anode catalyst layer 3B), the reaction of the above chemical reaction formula (4) occurs.

However, in the membrane-electrode assembly 11 according to the first embodiment and the polymer electrolyte fuel cell 20 including the membrane-electrode assembly (the polymer electrolyte fuel cell according to the first embodiment) 20, the first carbon layer 2A includes: The carbon that is disposed between the polymer electrolyte membrane 1 and the cathode catalyst layer 3A and that is used for the first carbon layer 2A is used for at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A. The ionization tendency is larger than the carbon ionization tendency, that is, the carbon contained in the first carbon layer 2A is more easily oxidized than the carbon contained in the cathode catalyst layer 3A. Yes. For this reason, the reaction of the chemical reaction formula (3) preferentially occurs in the carbon of the first carbon layer 2A, and the corrosion reaction of the catalyst-supporting carbon contained in the cathode catalyst layer 3A is suppressed.

As described above, in the membrane-electrode assembly 11 according to the first embodiment and the polymer electrolyte fuel cell (solid polymer fuel cell according to the first embodiment) 20 including the membrane-electrode assembly 11, It is possible to suppress deterioration of battery characteristics due to oxidative corrosion and improve durability.

(Embodiment 2)
Embodiment 2 of the present invention exemplifies a form in which a first carbon layer having carbon and ionomer is disposed between a polymer electrolyte membrane and an anode catalyst layer.

FIG. 4 is a cross-sectional view schematically showing a schematic configuration and operation of the polymer electrolyte fuel cell according to Embodiment 2 of the present invention. The fuel gas supplied to the polymer electrolyte fuel cell is temporarily Shows the state when deficient.

As shown in FIG. 4, the polymer electrolyte fuel cell 20 according to the second embodiment of the present invention (the membrane-electrode assembly 11 according to the second embodiment of the present invention) has a solid polymer fuel cell according to the first embodiment. Although the basic configuration is the same as that of the molecular fuel cell 20 (the membrane-electrode assembly 11 according to Embodiment 1), the first carbon layer 2A is interposed between the polymer electrolyte membrane 1 and the anode catalyst layer 3B. It is different in the arrangement. Therefore, a detailed description of the configuration of the polymer electrolyte fuel cell 20 according to Embodiment 2 is omitted.

By the way, in the conventional polymer electrolyte fuel cell, for example, when the fuel gas (hydrogen gas) supplied to the anode 5B is deficient, the fuel gas of the anode 5B (more precisely, the anode catalyst layer 3B) is deficient. In this region, the reaction of the chemical reaction formula (3) occurs, the catalyst-supporting carbon is corroded, the electrode catalyst of the anode 5B is greatly deteriorated, and the performance of the fuel cell is lowered.

However, in the polymer electrolyte fuel cell 20 according to the second embodiment configured as described above, the first carbon layer 2A is disposed between the polymer electrolyte membrane 1 and the anode catalyst layer 3B. Therefore, the reaction of the chemical reaction formula (3) preferentially occurs in the carbon of the first carbon layer 2A, and the corrosion reaction of the catalyst-supporting carbon contained in the anode catalyst layer 3B is suppressed.

Thus, in the polymer electrolyte fuel cell 20 according to the second embodiment (the membrane-electrode assembly 11 according to the second embodiment), the deterioration of the cell characteristics due to the oxidative corrosion of the carbon support in the catalyst layer is suppressed. , Durability can be improved.

(Embodiment 3)
Embodiment 3 of the present invention has a configuration in which a first carbon layer having carbon and ionomer is disposed between the polymer electrolyte membrane and the cathode catalyst layer and between the polymer electrolyte membrane and the anode catalyst layer. This is just an example.

FIG. 5 is a cross-sectional view schematically showing a schematic configuration of the polymer electrolyte fuel cell according to Embodiment 3 of the present invention.

As shown in FIG. 5, the polymer electrolyte fuel cell 20 according to the third embodiment of the present invention (the membrane-electrode assembly 11 according to the third embodiment of the present invention) has a solid polymer fuel cell according to the first embodiment. Although the basic configuration is the same as that of the molecular fuel cell 20 (the membrane-electrode assembly 11 according to Embodiment 1), the first carbon layer 2A is interposed between the polymer electrolyte membrane 1 and the anode catalyst layer 3B. Is different in that it is also disposed.

In the thus configured polymer electrolyte fuel cell 20 according to the third embodiment (membrane-electrode assembly 11 according to the third embodiment), the polymer electrolyte fuel cell 20 according to the first embodiment. In addition to the operational effects, the operational effects of the polymer electrolyte fuel cell 20 according to Embodiment 2 are exhibited.

(Embodiment 4)
Embodiment 4 of the present invention exemplifies a form in which a second carbon layer having carbon and ionomer is disposed between a cathode catalyst layer and a cathode gas diffusion layer.
[Configuration of membrane-electrode assembly and polymer electrolyte fuel cell including the same]
First, regarding the configuration of the membrane-electrode assembly according to Embodiment 4 of the present invention and the polymer electrolyte fuel cell including the same (FIG. 6 and FIG. 6), FIG. This will be described with reference to FIG.

FIG. 6 is a cross-sectional view schematically showing a schematic configuration of the membrane-electrode assembly according to Embodiment 4 of the present invention. FIG. 7 schematically shows a schematic configuration and operation of a polymer electrolyte fuel cell (solid polymer fuel cell according to Embodiment 4) of the present invention provided with the membrane-electrode assembly shown in FIG. It is sectional drawing, and shows a state when gas, such as fuel gas which exists in an anode, is purged with air when a polymer electrolyte fuel cell is stopped.

As shown in FIG. 6, a membrane-electrode assembly 11 according to Embodiment 4 of the present invention includes a polymer electrolyte membrane 1, a second carbon layer 2B, a cathode catalyst layer 3A, and a cathode gas diffusion layer 4A. A cathode 5A, an anode catalyst layer 3B, and an anode 5B having an anode gas diffusion layer 4B are provided. The polymer electrolyte membrane 1 is configured to selectively transport hydrogen. A cathode catalyst layer 3A is provided on one main surface of the polymer electrolyte membrane 1, and an anode catalyst layer 3B is provided on the other main surface. A second carbon layer 2B is provided on the main surface of the cathode catalyst layer 3A on the side not in contact with the polymer electrolyte membrane 1. Note that manifold holes such as a fuel gas supply manifold hole including through holes in the thickness direction are provided in the peripheral edge portion of the main surface of the polymer electrolyte membrane 1 (not shown).

On the other hand, the second carbon layer 2B has carbon and ionomer. The carbon used for the second carbon layer 2B is configured such that its ionization tendency is larger than the ionization tendency of carbon used for at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A. Specifically, the carbon used in the second carbon layer 2B, such as carbon that has been baked into the carrier carbon used in the catalyst layer to reduce the surface functional group serving as the oxidation start point, is used. By using carbon larger than the carbon used for the catalyst layer, the ionization tendency of the carbon used for the second carbon layer 2B can be relatively increased.

As a result, the carbon used for the second carbon layer 2B is more easily oxidized than the catalyst-carrying carbon (carrier carbon) of the catalyst layer, so that deterioration of battery characteristics due to oxidative corrosion of the catalyst layer is suppressed and durability is improved. Can do.

Further, in the second carbon layer 2B, the amount of the catalyst supported on the second carbon layer 2B is at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A (in the first embodiment, the anode catalyst layer 3B and the cathode catalyst layer 3A). Both) is configured to be smaller than the amount of catalyst supported. Thereby, it can suppress that it melt | dissolves by corrosion of carbon, precipitates in the polymer electrolyte membrane 1, and accelerates the film degradation of the polymer electrolyte membrane 1.

From the viewpoint of suppressing the catalyst contained in the second carbon layer 2B from being dissolved by the corrosion of carbon and precipitating in the polymer electrolyte membrane 1, the amount of catalyst supported on the second carbon layer 2B should be as small as possible. Preferably, the second carbon layer 2B is more preferably configured not to carry a catalyst. That is, the second carbon layer 2B is preferably composed of carbon and ionomer that do not carry a catalyst. In this case, the second carbon layer 2B does not exclude inclusion of substances other than carbon and ionomer not supporting the catalyst.

In the fourth embodiment, the catalyst loading amount of the second carbon layer 2B is configured to be smaller than the catalyst loading amounts of both the anode catalyst layer 3B and the cathode catalyst layer 3A. However, the present invention is not limited to this. The second carbon layer has only to be configured to be smaller than the amount of catalyst supported by at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A, and is larger than the amount of catalyst supported by the catalyst layer in contact with the second carbon layer 2B. You may be comprised so that the catalyst load of 2B may become small.

The second carbon layer 2B is configured such that the ionomer / carbon mass ratio (I / C) of the second carbon layer 2B is 0.6 or more from the viewpoint of maintaining the proton conductivity function. Preferably, from the viewpoint of maintaining gas diffusibility, the I / C is preferably configured to be 1.3 or less.

Thereby, the second carbon layer 2B has proton conductivity, and has sufficient gas diffusibility from the gas diffusion layer (here, the cathode gas diffusion layer 4A) to the catalyst layer (here, the cathode catalyst layer 3A). Since it has, the fall of an initial voltage can fully be suppressed.

Further, the second carbon layer 2B preferably has an EW of 700 or more from the viewpoint of maintaining the shape stability of the second carbon layer 2B, and from the viewpoint of maintaining the performance of the second carbon layer 2B. The EW is preferably 1100 or less. As a result, it is possible to improve the proton conductivity while ensuring the electron transfer property, the carbon contained in the second carbon layer 2B is more selectively oxidized and corroded, and the oxidation corrosion of the cathode catalyst layer 3A is prevented. It can suppress more effectively.

As shown in FIG. 7, the polymer electrolyte fuel cell (single cell) 20 according to the fourth embodiment includes a membrane-electrode assembly 11, a pair of

gaskets

6A and 6B, and a pair of conductive materials.

Separators

7A and 7B (cathode separator 7A and anode separator 7B).

The gasket 6A is provided around the second carbon layer 2B and the cathode 5A, and the gasket 6B is provided around the anode 5B. In addition, the

gaskets

6A and 6B.

separators

Then, a cell stack is formed by stacking the polymer electrolyte fuel cells 20 according to Embodiment 4 thus configured in the thickness direction (not shown). At this time, each manifold hole such as a fuel gas supply manifold hole provided in the polymer electrolyte membrane 1, the

gaskets

[Effects of membrane-electrode assembly and polymer electrolyte fuel cell including the same]
Next, referring to FIGS. 6 to 8, the membrane-electrode assembly 11 according to the fourth embodiment and the polymer electrolyte fuel cell including the same (the polymer electrolyte fuel cell according to the fourth embodiment) ) 20 effects will be described.

FIG. 8 is a cross-sectional view schematically showing the operation of a polymer electrolyte fuel cell (solid polymer fuel cell according to Embodiment 4) 20 including the membrane-electrode assembly 11 shown in FIG. A state when starting of the polymer electrolyte fuel cell 20 is started from a state in which air exists in the anode 5B and the cathode 5A.

As shown in FIG. 7, when the solid polymer fuel cell 20 is stopped, air is supplied to the anode 5B via the fuel gas supply manifold (not shown) and the fuel gas flow path 9, When the fuel gas or the like existing in the anode 5B (including the fuel gas supply manifold and the fuel gas channel 9) is purged with air, a region where hydrogen exists and a region where hydrogen does not exist are formed in the fuel gas channel 9.

Further, as shown in FIG. 8, from the standby state where air is present in the anode 5B and the cathode 5A of the polymer electrolyte fuel cell 20, through a fuel gas supply manifold (not shown) and the fuel gas flow path 9, The fuel gas is supplied to the anode 5B, and the oxidant gas is supplied to the cathode 5A via the oxidant gas supply manifold (not shown) and the oxidant gas flow path 8 (starting process of the polymer electrolyte fuel cell 20) ), A region where hydrogen exists and a region where hydrogen does not exist are formed in the fuel gas passage 9.

Then, when a region where hydrogen exists and a region where hydrogen does not exist are formed in the fuel gas flow path 9, a region where hydrogen exists and a region where hydrogen does not exist are also formed in the anode 5B. At this time, as shown in FIGS. 7 and 8, in the region where hydrogen exists in the anode 5B (more precisely, the anode catalyst layer 3B), the reaction of the chemical reaction formula (1) described above occurs, and the cathode 5A ( Precisely, the reaction of the chemical reaction formula (2) described above occurs in a region of the cathode catalyst layer 3A) opposite to the region where the hydrogen of the anode 5B exists.

However, in the membrane-electrode assembly 11 according to the fourth embodiment and the polymer electrolyte fuel cell (solid polymer fuel cell according to the fourth embodiment) 20 including the same, the second carbon layer 2B includes: The carbon that is disposed between the cathode catalyst layer 3A and the cathode gas diffusion layer 4A and that is used for the second carbon layer 2B is used for at least one of the anode catalyst layer 3B and the cathode catalyst layer 3A. The ionization tendency is larger than the ionization tendency of the carbon produced, that is, the carbon contained in the second carbon layer 2B is more easily oxidized than the carbon contained in the cathode catalyst layer 3A. Yes. For this reason, the reaction of the chemical reaction formula (3) preferentially occurs in the carbon of the second carbon layer 2B, and the corrosion reaction of the catalyst-supporting carbon contained in the cathode catalyst layer 3A is suppressed.

As described above, in the membrane-electrode assembly 11 according to the fourth embodiment and the polymer electrolyte fuel cell (solid polymer fuel cell according to the fourth embodiment) 20 including the membrane-electrode assembly 11, It is possible to suppress deterioration of battery characteristics due to oxidative corrosion and improve durability.

(Embodiment 5)
Embodiment 5 of the present invention exemplifies a form in which a second carbon layer having carbon and ionomer is disposed between an anode catalyst layer and an anode gas diffusion layer.

FIG. 9 is a cross-sectional view schematically showing a schematic configuration and operation of a polymer electrolyte fuel cell according to Embodiment 5 of the present invention. The fuel gas supplied to the polymer electrolyte fuel cell is temporarily Shows the state when deficient.

As shown in FIG. 9, the polymer electrolyte fuel cell 20 according to the fifth embodiment of the present invention (the membrane-electrode assembly 11 according to the fifth embodiment of the present invention) is the same as the solid polymer fuel cell according to the fourth embodiment. The basic configuration is the same as that of the molecular fuel cell 20 (the membrane-electrode assembly 11 according to Embodiment 4), but the second carbon layer 2B is interposed between the anode catalyst layer 3B and the anode gas diffusion layer 4B. It is different in the arrangement. Therefore, a detailed description of the configuration of the polymer electrolyte fuel cell 20 according to Embodiment 5 is omitted.

However, in the polymer electrolyte fuel cell 20 according to the fifth embodiment configured as described above, the second carbon layer 2B is disposed between the anode catalyst layer 3B and the anode gas diffusion layer 4B. Therefore, the reaction of the chemical reaction formula (3) preferentially occurs in the carbon of the second carbon layer 2B, and the corrosion reaction of the catalyst-supporting carbon contained in the anode catalyst layer 3B is suppressed.

Thus, in the polymer electrolyte fuel cell 20 according to the fifth embodiment (the membrane-electrode assembly 11 according to the fifth embodiment), the deterioration of the cell characteristics due to the oxidative corrosion of the carbon support in the catalyst layer is suppressed. , Durability can be improved.

(Embodiment 6)
In Embodiment 6 of the present invention, a second carbon layer having carbon and ionomer is disposed between the cathode catalyst layer and the cathode gas diffusion layer and between the anode catalyst layer and the anode gas diffusion layer. This is just an example.

FIG. 10 is a cross-sectional view schematically showing a schematic configuration of a polymer electrolyte fuel cell according to Embodiment 6 of the present invention.

As shown in FIG. 10, the polymer electrolyte fuel cell 20 according to the sixth embodiment of the present invention (the membrane-electrode assembly 11 according to the sixth embodiment of the present invention) has a solid high fuel cell according to the fourth embodiment. The basic configuration is the same as that of the molecular fuel cell 20 (the membrane-electrode assembly 11 according to Embodiment 1), but the second carbon layer 2B is interposed between the anode catalyst layer 3B and the anode gas diffusion layer 4B. Is different in that it is also disposed.

In the thus configured polymer electrolyte fuel cell 20 according to the sixth embodiment (membrane-electrode assembly 11 according to the sixth embodiment), the polymer electrolyte fuel cell 20 according to the fourth embodiment. In addition to the operational effects, the operational effects of the polymer electrolyte fuel cell 20 according to Embodiment 5 are exhibited.

(Embodiment 7)
In Embodiment 7 of the present invention, a first carbon layer having carbon and an ionomer is disposed between the polymer electrolyte membrane and the cathode catalyst layer, and carbon and carbon are interposed between the cathode catalyst layer and the cathode gas diffusion layer. The form in which the second carbon layer having an ionomer is disposed is illustrated.

FIG. 11 is a cross-sectional view schematically showing a schematic configuration of a polymer electrolyte fuel cell according to Embodiment 7 of the present invention.

As shown in FIG. 11, the polymer electrolyte fuel cell 20 according to the seventh embodiment of the present invention (the membrane-electrode assembly 11 according to the seventh embodiment of the present invention) is the same as the solid polymer fuel cell according to the first embodiment. Although the basic configuration is the same as that of the molecular fuel cell 20 (the membrane-electrode assembly 11 according to Embodiment 1), the second carbon layer 2B is interposed between the cathode catalyst layer 3A and the cathode gas diffusion layer 4A. It is different in the arrangement. Therefore, a detailed description of the configuration of the polymer electrolyte fuel cell 20 according to Embodiment 7 is omitted.

In the thus configured polymer electrolyte fuel cell 20 according to the seventh embodiment (membrane-electrode assembly 11 according to the seventh embodiment), the polymer electrolyte fuel cell 20 according to the first embodiment is used. In addition to the operational effects, the operational effects of the polymer electrolyte fuel cell 20 according to Embodiment 4 are exhibited.

In the seventh embodiment, the first carbon layer 2A is disposed between the polymer electrolyte membrane 1 and the cathode catalyst layer 3A. However, the present invention is not limited to this, and the polymer electrolyte membrane 1 and the anode catalyst layer 3B are not limited thereto. Or between the polymer electrolyte membrane 1 and the cathode catalyst layer 3A and between the polymer electrolyte membrane 1 and the anode catalyst layer 3B. Similarly, the second carbon layer 2B is disposed between the cathode catalyst layer 3A and the cathode gas diffusion layer 4A, but is not limited thereto, and is disposed between the anode catalyst layer 3B and the anode gas diffusion layer 4B. Alternatively, it may be disposed both between the cathode catalyst layer 3A and the cathode gas diffusion layer 4A and between the anode catalyst layer 3B and the anode gas diffusion layer 4B.

(Embodiment 8)
Embodiment 8 of the present invention is a fuel comprising a polymer electrolyte fuel cell, a solid polymer fuel cell in which a carbon layer is disposed between at least one of an anode catalyst layer and a cathode catalyst layer, and a purge air supplier. In the battery power generation system, a mode in which air is supplied to the anode and purged when the stop process of the fuel cell power generation system is performed is illustrated.

[Configuration of fuel cell power generation system]
FIG. 12 is a schematic diagram showing a schematic configuration of a fuel cell power generation system according to Embodiment 8 of the present invention.

As shown in FIG. 12, a fuel cell power generation system 100 according to Embodiment 8 of the present invention includes a polymer electrolyte fuel cell 20, a fuel gas supply device 21, and an oxidant gas supply device according to Embodiment 1. 22, a purge air supply unit 23, and a controller 24. In the eighth embodiment, the polymer electrolyte fuel cell 20 is used as a fuel cell stack in which a plurality of single cells are stacked.

For example, a hydrogen generator, a hydrogen cylinder, a hydrogen storage alloy, or the like can be used for the fuel gas supply device 21. In the present embodiment, an example of a hydrogen generator is shown. Since the hydrogen generator is well known, detailed description thereof is omitted.

The fuel gas supply unit 21 is connected to a polymer electrolyte fuel cell 20 (more precisely, an inlet of a fuel gas supply manifold not shown) via a fuel gas supply path 41. A first on-off valve 25 is provided in the middle of the fuel gas supply path 41. Thereby, it is possible to prevent the gas such as the fuel gas from flowing from the fuel gas supply path 41 to the fuel gas supply device 21 from flowing backward.

Also, an oxidant gas supply unit 22 is connected to the polymer electrolyte fuel cell 20 (precisely, an inlet of an oxidant gas supply manifold not shown) via an oxidant gas supply path 42. For the oxidant gas supply device 22, for example, a fan such as a blower or a sirocco fan can be used.

As a result, fuel gas is supplied from the fuel gas supply device 21 to the anode 5B (see FIGS. 1 to 3) of the polymer electrolyte fuel cell 20, and from the oxidant gas supply device 22 to the cathode of the polymer electrolyte fuel cell 20. Oxidant gas is supplied to 5A (see FIGS. 1 to 3). In the polymer electrolyte fuel cell 20, as described above, the supplied fuel gas and oxidant gas react electrochemically to generate water, and electricity and heat are generated. The fuel gas not used in the anode 5B is discharged to a fuel gas discharge manifold (not shown) of the polymer electrolyte fuel cell 20, and the oxidant gas not used in the cathode 5A is discharged to an oxidant gas discharge manifold (not shown). From the fuel cell power generation system 100 through the oxidant gas discharge path 44.

Further, the upstream end of the off-fuel gas passage 43 is connected to the outlet of the fuel gas discharge manifold (not shown) of the polymer electrolyte fuel cell 20, and the downstream end thereof is connected to the burner 21 </ b> A of the fuel gas supply device 21. It is connected. Further, a combustion exhaust gas passage 45 is connected to the burner 21A. Thereby, the fuel gas that has not been used in the anode 5B is supplied from the off-fuel gas flow path 43 to the burner 21A as off-fuel gas. In the burner 21 </ b> A, the off-fuel gas is used as a combustion fuel, and the combustion exhaust gas after combustion is discharged out of the fuel cell power generation system 100 from the combustion exhaust gas passage 45.

Further, the downstream end of the purge air supply path 46 is connected to the downstream side of the first on-off valve 25 of the fuel gas supply path 41, and the purge air supply unit 23 is connected to the upstream end thereof. Yes. A second on-off valve 26 is provided in the middle of the purge air supply path 46. For the purge air supply unit 23, for example, a fan such as a blower or a sirocco fan can be used. Accordingly, the purge air can be supplied from the purge air supply unit 23 to the anode 5B of the polymer electrolyte fuel cell 20 through the purge air supply path 46 and the fuel gas supply path 41.

Further, the controller 24 can be constituted by, for example, a microcomputer, a logic circuit, etc., and performs various controls of the fuel cell power generation system 100. Here, in the present invention, the controller means not only a single controller but also a controller group in which a plurality of controllers cooperate to execute control of the fuel cell power generation system 100. For this reason, the controller 24 does not need to be composed of a single controller, and a plurality of controllers may be arranged in a distributed manner so as to control the fuel cell power generation system 100 in cooperation with each other. Good.

[Operation of fuel cell power generation system]
Next, the operation of the fuel cell power generation system 100 according to Embodiment 8 will be described with reference to FIG.

First, the operation of stopping the operation of the fuel cell power generation system 100 will be described.

Here, “stopping the operation of the fuel cell power generation system” means an operation from when the controller 24 outputs a stop signal until the fuel cell power generation system 100 completes the stop processing. A series of actions aimed at ensuring hearing protection. It should be noted that after the completion of the stop process of the fuel cell power generation system 100, the controller 24 is operating, and the operation of the parts other than the controller 24 is stopped. It shifts to the standby state where the startup process is performed.

First, the controller 24 stops the operation of the fuel gas supplier 21 and the oxidant gas supplier 22 and closes the first on-off valve 25. As a result, the supply of fuel gas and oxidant gas to the polymer electrolyte fuel cell 20 is stopped.

Next, the controller 24 opens the second on-off valve 26 and operates the purge air supply 23. Then, the purge air is supplied from the purge air supply unit 23 to the fuel gas supply manifold (not shown) of the polymer electrolyte fuel cell 20 through the purge air supply path 46 and the fuel gas supply path 41. The purge air supplied to the fuel gas supply manifold flows through the fuel gas channel 9 of each single cell to purge the fuel gas existing in the fuel gas channel 9 and the anode 5B (see FIG. 2). At this time, as described above, in the fuel gas channel 9 and the anode 5B, a region where hydrogen is present and a region where hydrogen is not present are formed, but the chemical reaction formula is preferentially formed by the carbon of the first carbon layer 2A. The reaction (3) occurs, and the corrosion reaction of the catalyst-supporting carbon contained in the cathode catalyst layer 3A is suppressed. The purged fuel gas is supplied to the burner 21A through the off-fuel gas passage 43, burned by the burner 21A, and discharged out of the fuel cell power generation system 100.

Then, the controller 24 stops the operation of the purge air supply 23 when a predetermined time (a time during which the fuel gas in the polymer electrolyte fuel cell 20 is sufficiently purged with air) elapses. Then, the second on-off valve 26 is closed, and a transition is made to a standby state.

Next, the startup operation (startup process) of the fuel cell power generation system 100 will be described.

The controller 24 opens the first on-off valve 25 and operates the fuel gas supply device 21 and the oxidant gas supply device 22. Then, the fuel gas is supplied from the fuel gas supply device 21 to the anode 5B of the polymer electrolyte fuel cell 20, and the oxidant gas is supplied from the oxidant gas supply device 22 to the cathode 5A of the polymer electrolyte fuel cell 20. .

At this time, as described above, since air is present in the fuel gas channel 9 and the anode 5B, there are regions in the fuel gas channel 9 and the anode 5B where hydrogen is present and regions where hydrogen is not present. Although formed, the reaction of the chemical reaction formula (3) preferentially occurs in the carbon of the first carbon layer 2A, and the corrosion reaction of the catalyst-supported carbon contained in the cathode catalyst layer 3A is suppressed (see FIG. 3). On the other hand, in the region where the hydrogen of the anode 5B exists, the reaction of the chemical reaction formula (1) occurs, and in the region of the cathode 5A facing the region where the hydrogen of the anode 5B exists, the chemical reaction formula (2). Reaction occurs. Thereby, electricity and heat are generated in the polymer electrolyte fuel cell 20.

As described above, in the fuel cell power generation system 100 according to the fourth embodiment, since the polymer electrolyte fuel cell 20 according to the first embodiment is used, even if the inside of the fuel cell is replaced with air, the catalyst layer Deterioration can be suppressed. For this reason, not only simplification and cost reduction of the fuel cell power generation system 100 are possible, but also control of the fuel cell power generation system 100 can be simplified.

In the fuel cell power generation system 100 according to the eighth embodiment, the polymer electrolyte fuel cell 20 according to the first embodiment is used, but the solid polymer according to any one of the second to seventh embodiments is used. A polymer fuel cell 20 may be used.

(Embodiment 9)
Embodiment 9 of the present invention is a fuel comprising a polymer electrolyte fuel cell, a solid polymer fuel cell in which a carbon layer is disposed between at least one of an anode catalyst layer and a cathode catalyst layer, and a purge air supplier. In the battery power generation system, the purge air supply unit is exemplified by an oxidant gas supply unit and a bypass flow path.

[Configuration of fuel cell power generation system]
FIG. 13 is a schematic diagram showing a schematic configuration of a fuel cell power generation system according to Embodiment 9 of the present invention.

As shown in FIG. 13, the fuel cell power generation system 100 according to the ninth embodiment of the present invention has the same basic configuration as the fuel cell power generation system 100 according to the eighth embodiment, but the purge air supply device is the same. The oxidant gas supply unit 22 is different from the oxidant gas supply unit 22 in that it is configured to supply an oxidant gas from the oxidant gas supply unit 22 to the anode 5B.

Specifically, the bypass channel 47 has an upstream end connected in the middle of the oxidant gas supply path 42 and a downstream end connected to the downstream side of the first on-off valve 25 of the fuel gas supply path 41. . A third opening / closing valve 27 is provided in the middle of the bypass flow path 47. Further, a fourth on-off valve 28 is provided in the middle of the oxidant gas discharge path 44.

[Operation of fuel cell power generation system]
Next, the operation for stopping operation of the fuel cell power generation system 100 according to Embodiment 9 will be described. In addition, since the starting process of the fuel cell power generation system 100 is the same as that of the fuel cell power generation system 100 according to Embodiment 8, detailed description thereof is omitted.

First, the controller 24 stops the operation of the fuel gas supply device 21 and closes the first on-off valve 25. Thereby, the supply of the fuel gas to the polymer electrolyte fuel cell 20 is stopped.

Next, the controller 24 opens the third on-off valve 27 and closes the fourth on-off valve 28. Then, the oxidant gas supplied from the oxidant gas supply device 22 to the oxidant gas supply path 42 flows as the purge air through the bypass flow path 47 and the fuel gas supply path 41, and the polymer electrolyte fuel cell 20. To a fuel gas supply manifold (not shown). The purge air supplied to the fuel gas supply manifold flows through the fuel gas channel 9 of each single cell to purge the fuel gas existing in the fuel gas channel 9 and the anode 5B (see FIG. 2). At this time, as described above, in the fuel gas channel 9 and the anode 5B, a region where hydrogen is present and a region where hydrogen is not present are formed, but the chemical reaction formula is preferentially formed by the carbon of the first carbon layer 2A. The reaction (3) occurs, and the corrosion reaction of the catalyst-supporting carbon contained in the cathode catalyst layer 3A is suppressed.

As described above, even the fuel cell power generation system 100 according to the ninth embodiment has the same effects as the fuel cell power generation system 100 according to the eighth embodiment.

(Embodiment 10)
Embodiment 10 of the present invention is a fuel comprising a polymer electrolyte fuel cell, a polymer electrolyte fuel cell in which a carbon layer is disposed between at least one of an anode catalyst layer and a cathode catalyst layer, and a purge air supplier. In the battery power generation system, an example in which the purge air supply unit is configured by an air release channel and an on-off valve provided in the air release channel.

[Configuration of fuel cell power generation system]
FIG. 14 is a schematic diagram showing a schematic configuration of the fuel cell power generation system according to Embodiment 10 of the present invention.

As shown in FIG. 14, the fuel cell power generation system 100 according to the tenth embodiment of the present invention has the same basic configuration as the fuel cell power generation system 100 according to the eighth embodiment. , And the fifth open / close valve 29 (the open / close valve of the present invention) provided in the open air channel 48 is different.

Specifically, one end of the air release channel 48 is connected to the downstream side of the first on-off valve 25 of the fuel gas supply channel 41, and the other end is open to the atmosphere. A fifth on-off valve 29 is provided in the middle of the air release channel 48.

[Operation of fuel cell power generation system]
Next, the operation for stopping the operation of the fuel cell power generation system 100 according to Embodiment 10 will be described. In addition, since the starting process of the fuel cell power generation system 100 is the same as that of the fuel cell power generation system according to Embodiment 8, detailed description thereof is omitted.

First, the controller 24 stops the operation of the fuel gas supplier 21 and the oxidant gas supplier 22 and closes the first on-off valve 25. As a result, the supply of the fuel gas and the oxidant gas to the polymer electrolyte fuel cell 20 is stopped.

Next, the controller 24 opens the fifth on-off valve 29. Then, since the inside of the polymer electrolyte fuel cell 20 has a negative pressure due to the temperature drop due to the operation stop and the gas consumption of both electrodes due to the cross leak, air (purge air) is discharged from the atmosphere open end of the atmosphere open flow path 48. It flows in, flows through the open air channel 48 and the fuel gas supply channel 41, and is supplied to a fuel gas supply manifold (not shown) of the polymer electrolyte fuel cell 20. The purge air supplied to the fuel gas supply manifold flows through the fuel gas channel 9 of each single cell and mixes with the fuel gas existing in the fuel gas channel 9 and the anode 5B (see FIG. 2). . At this time, as described above, in the fuel gas channel 9 and the anode 5B, a region where hydrogen is present and a region where hydrogen is not present are formed, but the chemical reaction formula is preferentially formed by the carbon of the first carbon layer 2A. The reaction (3) occurs, and the corrosion reaction of the catalyst-supporting carbon contained in the cathode catalyst layer 3A is suppressed.

Thus, even the fuel cell power generation system 100 according to the tenth embodiment has the same operational effects as the fuel cell power generation system 100 according to the eighth embodiment.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

First, examples and comparative examples of the polymer electrolyte fuel cell in which the first carbon layer is provided between the polymer electrolyte membrane and the catalyst layer will be described.

Example 1
In Example 1, the polymer electrolyte fuel cell 20 described in Embodiment 1 was produced as follows.

Ketjen Black EC (made by International Co., Ltd.) as the carbon of the first carbon layer 2A is mixed with an ionomer solution (SE10072 (EW990), 10 wt%: made by DuPont) so that I / C = 2.0, and ultrasonic waves are obtained. Dispersion was performed to form a slurry. Then, this slurry was coated on a polypropylene sheet having a thickness of 50 μm with a bar coater so that the thickness upon drying was 5 μm, and dried at room temperature.

Next, the coated sheet is cut into a predetermined electrode size (60 mm square) with a punching die, and the cut sheet is applied to one side of a polymer electrolyte membrane 1 (Gore select membrane: manufactured by Gore) at 130 ° C. and 1 MPa. The first carbon layer 2A was thermally transferred from the polypropylene sheet to the polymer electrolyte membrane 1.

Next, Ketjen Black EC (manufactured by International Co., Ltd.) as a catalyst carrier was calcined in a nitrogen atmosphere at 2700 ° C. for 10 hours, and the graphitized carbon black was immersed in an aqueous chloroplatinic acid solution for reduction. The platinum catalyst was supported on the surface of the carbon powder by the treatment. The weight ratio of carbon to supported platinum was 1: 1.

Next, the catalyst-carrying particles were dispersed in an ionomer solution (SE10072 (EW990) 10 wt%: manufactured by DuPont) so that I / C = 0.8, and slurried. The slurry was coated on a 50 μm thick polypropylene sheet with a bar coater so that the weight of platinum was 0.3 mg / cm ² and dried at room temperature.

Next, the coated sheet is cut into a predetermined electrode size (60 mm square) with a punching die, and the cut sheet is placed on both sides of the polymer electrolyte membrane 1 in which the first carbon layer 2A is disposed on one side (more precisely, The main surface of the polymer electrolyte membrane 1 where the first carbon layer 2A is not disposed and the main surface of the first carbon layer 2A which is not in contact with the polymer electrolyte membrane 1) and the first carbon layer 2A The catalyst layer was thermally transferred from the polypropylene sheet to the polymer electrolyte membrane 1 at 130 ° C. and 1 MPa so as to overlap to form the anode catalyst layer 3B and the cathode catalyst layer 3A.

On the other hand, a carbon fiber nonwoven fabric (TGP-H-120: manufactured by Toray Industries, Inc.) having a thickness of 360 μm serving as an electrode was impregnated into a fluororesin-containing aqueous dispersion (neoflon ND1: manufactured by Daikin Industries), and then dried. Further, a water repellent carbon layer is formed on one surface of the carbon nonwoven fabric by applying an ink obtained by mixing a conductive carbon powder and an aqueous solution in which PTFE fine powder is dispersed using a screen printing method. The mixture was heated at 0 ° C. for 30 minutes to decompose and remove the surfactant contained in the solvent, and this was punched with a punch having an electrode size (60 mm square) to obtain a gas diffusion layer. Two gas diffusion layers are prepared and sandwiched between both sides of the membrane-catalyst layer assembly by these gas diffusion layers, and a pair of layers composed of a composite material of silicon rubber / polyetherimide / silicon rubber is laminated. The

gaskets

6A and 6B were placed on the outer periphery of the electrode and thermocompression bonded at 130 ° C. and 1 MPa for 10 minutes to obtain a membrane-electrode assembly 11. The electrode on which the first carbon layer 2A of the membrane-electrode assembly 11 is disposed is used as the cathode 5A, and is sandwiched between the anode separator 7B and the cathode separator 7A. Cell) 20 was produced.

(Example 2)
The polymer electrolyte fuel cell 20 of Example 2 was fabricated in the same manner as the polymer electrolyte fuel cell 20 of Example 1 except that the first carbon layer 2A was configured with I / C = 1.9.

(Example 3)
The polymer electrolyte fuel cell 20 of Example 2 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 1 except that the first carbon layer 2A was configured with I / C = 1.3.

(Comparative Example 1)
The polymer electrolyte fuel cell 20 of Comparative Example 1 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 1, except that the first carbon layer 2A was not provided.

(Comparative Example 2)
The polymer electrolyte fuel cell 20 of Comparative Example 2 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 1 except that the first carbon layer 2A was configured with I / C = 1.2.

(Comparative Example 3)
The polymer electrolyte fuel cell 20 of Comparative Example 3 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 1, except that the first carbon layer 2A was configured with I / C = 2.1.

Next, a performance evaluation test was conducted using these polymer electrolyte fuel cells.

(Performance evaluation test)
In the performance evaluation test, a start / stop test assuming a system (see Embodiment 8 and FIG. 12) that opens the gas path of the fuel cell (the path through which fuel gas or oxidant gas flows during power generation operation) to the atmosphere. Was performed according to the following procedure. The power generation conditions are: current density 0.2 A / cm ² , hydrogen utilization 70%, oxygen utilization 50%, fuel gas 75% hydrogen, carbon dioxide 25% mixed gas, oxidant gas air , The dew point of the fuel gas is set to 70 ° C., the dew point of the oxidant gas is set to 70 ° C., and the battery temperature is set to 70 ° C. After the electric load is cut off, the cathode 5A is stopped by supplying the humidified air and opened to the atmosphere. Circulated non-humidified air at a flow rate of 2% of the hydrogen flow rate during power generation. The cycle of power generation time 30 minutes and stop time 30 minutes was repeated 4000 times. And the voltage and deterioration rate before and behind a test were measured, and the result was shown in FIG. FIG. 15 is a table showing the voltage and deterioration rate of each polymer electrolyte fuel cell before and after the performance evaluation test.

As shown in FIG. 15, in the polymer electrolyte fuel cells 20 of Examples 1 to 3 in which the first carbon layer 2A is disposed between the cathode catalyst layer 3A and the polymer electrolyte 1, the operation is stopped and started. Compared with the polymer electrolyte fuel cell 20 of Comparative Example 1 that does not have the first carbon layer 2A, the anode 5B has a region where hydrogen is present and a region where hydrogen is not present for a long time. The deterioration rate is greatly improved. Further, in the polymer electrolyte fuel cells 20 of Examples 1 to 3, the initial voltage is not changed as compared with the polymer electrolyte fuel cell 20 of Comparative Example 1, and the first carbon layer 2A is used as the cathode catalyst layer 3A. It has been found that there is almost no influence on the normal power generation performance even if it is disposed between the polymer electrolyte membrane 1 and the polymer electrolyte membrane 1.

On the other hand, in the polymer electrolyte fuel cell 20 of Comparative Example 2, it was found that although the deterioration rate was improved, the initial cell voltage was greatly reduced as compared with the polymer electrolyte fuel cell 20 of Comparative Example 1. Further, in the polymer electrolyte fuel cell 20 of Comparative Example 3, it was found that although the improvement of the initial voltage was seen as compared with the polymer electrolyte fuel cell 20 of Comparative Example 1, the deterioration rate was lowered. .

From these results, the carbon in the first carbon layer 2A is preferentially oxidatively corroded because the carbon in the first carbon layer 2A uses carbon having a higher ionization tendency than the carbon in the cathode catalyst layer 3A. Therefore, it was shown that the carbon of the cathode catalyst layer 3A is not oxidized and corroded. Further, when the I / C in the first carbon layer 2A is smaller than 1.3 (Comparative Example 2 I / C = 1.2), the proton conductivity of the first carbon layer 2A is lowered and the initial voltage is lowered. If the I / C in the first carbon layer 2A is larger than 2.0 (Comparative Example 3 I / C = 2.1), the electron conductivity is lowered, and the first carbon layer 2A It was suggested that the performance (suppressing oxidative deterioration of the catalyst layer) is reduced.

In the present embodiment, the effect of the first carbon layer 2A under the condition that the region where hydrogen is present and the region where hydrogen is not present is formed in the anode 5B. However, an inert gas (for example, nitrogen gas or Even in a fuel cell power generation system in which the anode 5B is purged with methane gas or the like and an inert gas is present in the anode 5B in a standby state, the battery voltage is low in an OCV state with no load or a power generation state with a high low load ratio. Therefore, it is clear that the first carbon layer 2 </ b> A is effective in suppressing the oxidative decay of carbon in the catalyst layer.

In the present embodiment, the formation of the first carbon layer 2A was formed by thermal transfer to the polymer electrolyte membrane 1. However, the present invention is not limited thereto, and a catalyst layer is formed on the main surface of the gas diffusion layer. The first carbon layer 2A may be formed on the main surface of the catalyst layer, or the first carbon layer 2A may be formed on the main surface of the polymer electrolyte membrane 1 by spray coating.

Next, examples and comparative examples of the polymer electrolyte fuel cell in which the second carbon layer is provided between the catalyst layer and the gas diffusion layer will be described.

Example 4
In Example 4, the polymer electrolyte fuel cell 20 described in Embodiment 4 was produced as follows.

Ketjen Black EC (manufactured by International Co., Ltd.) as a catalyst carrier was baked at 2700 ° C. for 10 hours in a nitrogen atmosphere, and the graphitized carbon black was immersed in an aqueous chloroplatinic acid solution, and carbon was reduced by reduction treatment. A platinum catalyst was supported on the surface of the powder. The weight ratio of carbon to supported platinum was 1: 1.

Next, the coated sheet was cut into a predetermined electrode size (60 mm square) with a punching die, and the cut sheets were arranged on both surfaces of the polymer electrolyte membrane 1 so as to overlap each other when viewed from the thickness direction. Then, the catalyst layer was thermally transferred from the polypropylene sheet to the polymer electrolyte membrane 1 at 130 ° C. and 1 MPa to form the anode catalyst layer 3B and the cathode catalyst layer 3A.

Next, ketjen black EC (manufactured by International) was mixed with the ionomer solution (SE10072 (EW990), 10 wt%: DuPont) as the carbon of the second carbon layer 2B so that I / C = 0.6. Then, ultrasonic dispersion was performed to make a slurry. Then, this slurry was coated on a polypropylene sheet having a thickness of 50 μm with a bar coater so that the thickness upon drying was 5 μm, and dried at room temperature.

Next, the coated sheet was cut into a predetermined electrode size (60 mm square) with a punching die, and the cut sheet was placed on the main surface of the cathode catalyst layer 3A of the polymer electrolyte membrane 1. Then, the second carbon layer 2B was thermally transferred from the polypropylene sheet to the main surface of the cathode catalyst layer 3A of the polymer electrolyte membrane 1 at 130 ° C. and 1 MPa.

On the other hand, a carbon fiber nonwoven fabric (TGP-H-120: manufactured by Toray Industries, Inc.) having a thickness of 360 μm serving as an electrode was impregnated into a fluororesin-containing aqueous dispersion (neoflon ND1: manufactured by Daikin Industries), and then dried. Furthermore, a water-repellent carbon layer is formed on one surface of the carbon nonwoven fabric by applying an ink obtained by mixing a conductive carbon powder and an aqueous solution in which PTFE fine powder is dispersed using a screen printing method. The mixture was heated at 0 ° C. for 30 minutes to decompose and remove the surfactant contained in the solvent, and this was punched with a punch having an electrode size (60 mm square) to obtain a gas diffusion layer. Two gas diffusion layers are prepared and sandwiched between both sides of the membrane-catalyst layer assembly by these gas diffusion layers, and a pair of layers composed of a composite material of silicon rubber / polyetherimide / silicon rubber is laminated. The

gaskets

6A and 6B were placed on the outer periphery of the electrode and thermocompression bonded at 130 ° C. and 1 MPa for 10 minutes to obtain a membrane-electrode assembly 11. The electrode on which the second carbon layer 2B of the membrane-electrode assembly 11 is disposed is used as the cathode 5A, and is sandwiched between the anode separator 7B and the cathode separator 7A. Cell) 20 was produced.

(Example 5)
The polymer electrolyte fuel cell 20 of Example 5 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 4 except that the second carbon layer 2B was configured with I / C = 1.3.

(Comparative Example 4)
The polymer electrolyte fuel cell 20 of Comparative Example 4 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 4 except that the second carbon layer 2B was not provided.

(Comparative Example 5)
The polymer electrolyte fuel cell 20 of Comparative Example 5 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 4 except that the second carbon layer 2B was configured with I / C = 1.4.

(Comparative Example 6)
The polymer electrolyte fuel cell 20 of Comparative Example 6 was produced in the same manner as the polymer electrolyte fuel cell 20 of Example 4 except that the second carbon layer 2B was configured with I / C = 0.5.

(Performance evaluation test)
In the performance evaluation test, a start / stop test assuming a system (see Embodiment 8 and FIG. 12) that opens the gas path of the fuel cell (the path through which fuel gas or oxidant gas flows during power generation operation) to the atmosphere. Was performed according to the following procedure. The power generation conditions are: current density 0.2 A / cm ² , hydrogen utilization 70%, oxygen utilization 50%, fuel gas 75% hydrogen, carbon dioxide 25% mixed gas, oxidant gas air , The dew point of the fuel gas is set to 70 ° C., the dew point of the oxidant gas is set to 70 ° C., and the battery temperature is set to 70 ° C. Circulated non-humidified air at a flow rate of 2% of the hydrogen flow rate during power generation. The cycle of power generation time 30 minutes and stop time 30 minutes was repeated 4000 times. And the voltage and deterioration rate before and behind a test were measured, and the result was shown in FIG. FIG. 16 is a table showing the voltage and deterioration rate of each polymer electrolyte fuel cell before and after the performance evaluation test.

As shown in FIG. 16, in the polymer electrolyte fuel cells 20 of Example 4 and Example 5 in which the second carbon layer 2B is disposed between the cathode catalyst layer 3A and the cathode gas diffusion layer 4A, the operation is stopped. Compared with the polymer electrolyte fuel cell 20 of Comparative Example 4 that does not have the second carbon layer 2B, although the region where hydrogen is present and the region where it is not present are formed for a long time at the anode 5B during startup. The deterioration rate is greatly improved. Further, in the polymer electrolyte fuel cells 20 of Example 4 and Example 5, the initial voltage is not changed as compared with the polymer electrolyte fuel cell 20 of Comparative Example 4, and the second carbon layer 2B is used as the cathode catalyst. It has been found that even if it is arranged between the layer 3A and the cathode gas diffusion layer 4A, there is almost no influence on the normal power generation performance.

On the other hand, in the polymer electrolyte fuel cell 20 of Comparative Example 5, it was found that although the deterioration rate was improved as compared with the polymer electrolyte fuel cell 20 of Comparative Example 4, the decrease in the initial cell voltage was large. Further, in the polymer electrolyte fuel cell 20 of Comparative Example 6, it was found that although the initial voltage was improved as compared with the polymer electrolyte fuel cell 20 of Comparative Example 4, the deterioration rate was lowered. .

From these results, the carbon in the second carbon layer 2B is preferentially oxidatively corroded because the carbon in the second carbon layer 2B uses carbon having a higher ionization tendency than the carbon in the cathode catalyst layer 3A. Therefore, it was shown that the carbon of the cathode catalyst layer 3A is not oxidized and corroded. Further, if the I / C in the second carbon layer 2B is larger than 1.3 (Comparative Example 5 I / C = 1.4), the gas diffusibility of the second carbon layer 2B is lowered and the initial voltage is lowered. When the I / C in the second carbon layer 2B is smaller than 0.6 (Comparative Example 6 I / C = 0.5), the proton conductivity decreases, and the second carbon layer 2B It was suggested that the performance (suppressing oxidative deterioration of the catalyst layer) is reduced.

In the present embodiment, the effect of the second carbon layer 2B under the condition that the region where hydrogen is present and the region where the hydrogen is not present is formed in the anode 5B is verified, but an inert gas (for example, nitrogen gas or Even in a fuel cell power generation system in which the anode 5B is purged with methane gas or the like and an inert gas is present in the anode 5B in a standby state, the battery voltage is low in an OCV state with no load or a power generation state with a high low load ratio. Therefore, it is clear that the second carbon layer 2B has an effect of suppressing the oxidative decay of carbon in the catalyst layer.

In this embodiment, the second carbon layer 2B is formed by thermally transferring to the catalyst layer. However, the present invention is not limited to this, and the catalyst layer is formed on the main surface of the gas diffusion layer. The second carbon layer 2B may be formed on the main surface, or the second carbon layer 2B may be formed on the main surface of the gas diffusion layer by spray coating.

From the above description, many modifications and other embodiments of the present invention are apparent to persons skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the scope of the invention. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

The membrane-electrode assembly and solid polymer fuel cell of the present invention can suppress the deterioration of battery characteristics due to oxidative corrosion of the carbon support in the catalyst layer and can improve the durability. Useful.

The fuel cell power generation system of the present invention is useful in the technical field of fuel cells because the control of the fuel cell power generation system can be simplified, and the fuel cell power generation system can be simplified and reduced in cost.

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2A 1st carbon layer 2B 2nd carbon layer 3A Cathode catalyst layer 3B Anode catalyst layer 4A Cathode gas diffusion layer 4B Anode gas diffusion layer 5A Cathode 5B Anode 6A Gasket 6B Gasket

7A Cathode separator

7B Anode separator 8 Oxidizing agent Gas flow path 9 Fuel gas flow path 10 Cooling medium flow path 11 Membrane-electrode assembly 20 Polymer electrolyte fuel cell 21 Fuel gas supply 21A Burner 22 Oxidant gas supply 23 Purge air supply 24 Controller 25 1 on-off valve 26 second on-off valve 27 third on-off valve 28 fourth on-off valve 29 fifth on-off valve 41 fuel gas supply passage 42 oxidant gas supply passage 43 off-fuel gas passage 44 oxidant gas discharge passage 45 combustion exhaust gas flow Path 46 Purge air supply path 47 Bypass flow path 48 Atmospheric release flow path 00 fuel cell power generation system

Claims

An anode having an anode catalyst layer comprising a catalyst-supporting carbon and an ionomer and an anode gas diffusion layer;
A cathode having a cathode catalyst layer including a catalyst-supporting carbon and an ionomer and a cathode gas diffusion layer;
A polymer electrolyte membrane disposed between the anode catalyst layer and the cathode catalyst layer;
A first carbon layer disposed between at least one of the anode catalyst layer and the cathode catalyst layer and the polymer electrolyte membrane, and having carbon and an ionomer; and between the anode catalyst layer and the anode gas diffusion layer; and At least one carbon layer disposed between at least one of the cathode catalyst layer and the cathode gas diffusion layer and having carbon and an ionomer;
In the first carbon layer and the second carbon layer, the ionization tendency of carbon in the first carbon layer and the second carbon layer is based on the ionization tendency of the catalyst-supporting carbon in at least one of the anode catalyst layer and the cathode catalyst layer. The catalyst loading amount of the first carbon layer and the second carbon layer is configured to be smaller than the catalyst loading amount of at least one of the anode catalyst layer and the cathode catalyst layer. Membrane-electrode assembly.
The membrane-electrode assembly according to claim 1, wherein the first carbon layer and the second carbon layer are composed of carbon and ionomer not supporting a catalyst.
The membrane-electrode assembly according to claim 1, wherein an ionomer / carbon mass ratio (I / C) of the first carbon layer is 1.3 or more and 2.0 or less.
The membrane-electrode assembly according to claim 1 or 3, wherein an ionomer / carbon mass ratio (I / C) of the second carbon layer is 0.6 or more and 1.3 or less.
The membrane-electrode assembly according to any one of claims 2 to 4, wherein the EW of the ionomer of the first carbon layer and the second carbon layer is 700 or more and 1100 or less.
A membrane-electrode assembly according to any one of claims 1 to 5;
A solid polymer fuel cell comprising: a pair of conductive separators arranged in a plate shape so as to sandwich the membrane-electrode assembly.
A polymer electrolyte fuel cell according to claim 6;
A fuel gas supplier for supplying fuel gas to the anode via a fuel gas supply path;
An oxidant gas supply device for supplying an oxidant gas to the cathode via an oxidant gas supply path;
An off-fuel gas flow path through which fuel gas not used in the anode flows;
A purge air supply;
A fuel cell power generation system comprising a controller;
The controller is configured to control the purge air supply unit so as to supply and purge air to the anode when the fuel cell power generation system is stopped.
The purge air supply device is configured by the oxidant gas supply device and a bypass flow path configured to supply the oxidant gas from the oxidant gas supply device to the anode. Fuel cell power generation system.
The purge air supply is connected to the fuel gas supply path or the off-fuel gas flow path, and includes an air open flow path having an air open end and an open / close valve provided in the air open flow path. The fuel cell power generation system according to claim 7.
The fuel cell power generation system according to claim 7, wherein the controller is configured to perform a startup process of the fuel cell power generation system from a standby state in which air exists in the anode and the cathode.