JP2002134120A - Electrode for fuel cell and fuel cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for a fuel cell for achieving good generating efficiency by securing abundant three-phase interfaces in relatively easy construction while keeping cost down, and the fuel cell using the same. SOLUTION: A catalyst layer 221 is formed of ion exchange resin particles 221a and a Pt/C221b consisting of platinum particles 2212 and porous carbon particles 2211 having a specific surface area of 300 m2/g or larger and being hydrophilic with electrolytic treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell electrode and a polymer electrolyte fuel cell using the same.

[0002]

2. Description of the Related Art Generally, a fuel cell supplies an anode gas containing hydrogen to an anode side and a cathode gas (oxidizing gas) containing oxygen to a cathode side, and electrochemically reacts hydrogen and oxygen to generate power. Do. Air is generally used as the cathode gas. As the anode gas, a hydrogen-rich reformed gas obtained by reforming a fuel gas such as a natural gas or a light hydrocarbon such as naphtha in addition to pure hydrogen gas is used.

[0003] There are various types of fuel cells. In recent years, studies have been actively made on polymer electrolyte fuel cells (PEFCs) using a solid polymer membrane as an electrolyte. A polymer electrolyte fuel cell has a basic structure in which an electrolyte membrane (solid polymer membrane) made of a fluorine-based cation exchange resin or the like is disposed between two electrodes. The electrodes are
It comprises a catalyst layer and a gas diffusion layer, of which the catalyst layer is disposed so as to face the solid polymer membrane.

The catalyst layer is formed by mixing porous catalyst-supporting carbon (eg, platinum-supporting carbon (Pt / C)) supporting a catalyst and ion-exchange resin particles, and forming the mixture into a sheet. A power generation reaction (electrode reaction) at the electrode is performed on the catalyst, and the ion exchange resin forms a discharge path of water generated during power generation while transporting protons generated on the anode side. The carbon of Pt / C has a function of ensuring conductivity for extracting generated power.

The power generation reaction mainly occurs at an interface where three phases of a catalyst, an ion exchange resin, and a gas (cathode gas or anode gas) are in contact, that is, a so-called three-phase interface. Therefore, in order to obtain good power generation efficiency, it is desirable to ensure abundant three-phase interfaces in the catalyst layer. When the number of three-phase interfaces is small, the power generation reaction hardly occurs, and the cell output is hardly excellent. For example, even in a configuration in which the catalyst and the ion exchange resin are in contact with each other, it is still difficult to improve the cell output unless the reaction gas is sufficiently diffused into the catalyst layer.

[0006]

In contrast, for example, in Japanese Patent Application Laid-Open Nos. 9-176622 and 9-283154, the pore volume of the catalyst layer and Pt / C is increased, and A technique for improving the gas flow in the above is disclosed, which is considered to be one measure for securing the three-phase interface, however, it cannot be said to be a sufficient measure, and there is room for further improvement. In addition, a method of increasing the amount of the catalyst in order to secure abundant three-phase interfaces can be considered, but in this case, the problem of cost becomes remarkable.

As described above, there is still room for technical improvement in the field of fuel cells. The present invention has been made in view of the above problems, and an object of the present invention is to obtain good power generation efficiency by securing abundant three-phase interfaces with a relatively simple configuration while suppressing costs. It is an object of the present invention to provide a possible fuel cell electrode and a fuel cell using the same.

[0008]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to solve the above-mentioned problems, the present invention provides a carrier carrying catalyst particles and an ion exchanger so as to contact the catalyst particles. Is a fuel cell electrode laminated with a gas diffusion layer, wherein the carrier comprises:
Porous particles made of a conductive material having a specific surface area of 300 m ² / g or more that has been subjected to hydrophilic treatment, and of the total surface area of the catalyst particles in the catalyst layer, the surface area in contact with the ion exchanger is 40%.
% Or more.

As described above, since the conductive porous particles having a relatively large specific surface area (300 m ² / g or more) are used as the carrier, a large surface for supporting the catalyst on the carrier is secured. Therefore, a wide contact area can be secured even with a small amount of catalyst. On the other hand, when the specific surface area of the support is large, the catalyst present in the very fine pores on the support surface is difficult to be covered with the ion exchanger, so that the contact rate of the catalyst particles to the ion exchanger generally tends to be low. In the present invention, by subjecting the support to hydrophilic treatment, the contact area of the catalyst particles with the ion exchanger can be increased (40% or more of the total area of the catalyst particles in the catalyst layer is the contact area). This increases the utilization of the catalyst.

As described above, in the present invention, the contact between the catalyst and the ion exchanger is improved, the flow of the reaction gas is improved, and the three-phase interface is secured abundantly. It becomes possible to take out well. In addition, the above effect can be obtained even if the amount of the catalyst is reduced, so that a cost reduction effect can be expected. Here, the above numerical values have been clarified through experiments by the inventors as numerical values at which the effects of the present invention can be favorably obtained.

As the hydrophilic treatment, an electrolytic treatment can be used. Further, specifically, it is desirable to use carbon particles as the conductive particles. further,
A pore having a diameter of 500 nm or less is formed in the catalyst layer,
The pore volume corresponding to pores below nm is 0.5 c / g of catalyst layer
When it is set to c or more, the utilization rate of the catalyst can be increased.

It is desirable that the pore volume corresponding to pores of 500 nm or less be 0.6 cc or more per gram of the catalyst layer, since a further effect can be obtained. If such a fuel cell electrode is applied to a fuel cell, an output with good power generation efficiency can be obtained. The present invention also provides a catalyst particle having a specific surface area.
A first step of making the carbon particles hydrophilic by electrolysis while supporting the carbon particles as a carrier of 300 m ² / g or more, the carrier supporting the catalyst particles, and the catalyst particles and the ion exchanger. Mixing, a second step of producing a porous catalyst layer so that the surface area in contact with the ion exchanger is 40% or more of the total area of the catalyst particles,
And producing a fuel cell electrode by laminating the catalyst layer and the gas diffusion layer.

Thus, a catalyst layer having a high catalyst utilization rate can be formed as described above. Further, the fuel cell of the present invention is manufactured by passing at least one of an anode and a cathode by such a method for a fuel cell electrode and a step of manufacturing a cell using the manufactured electrode. be able to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Embodiment Hereinafter, a cell unit of a polymer electrolyte fuel cell which is an application example of the present invention will be described. Since the main feature of the present invention lies in the cell configuration, first, the basic configuration of the polymer electrolyte fuel cell will be described.
Next, the cell configuration will be described in detail.

1-1. Configuration of Cell Unit FIG. 1 is an assembly diagram of a cell unit 10 constituting the polymer electrolyte fuel cell according to the present embodiment. As shown in the figure, the cell unit 10 includes a cathode-side channel plate.
It has a configuration in which the cell 20 is arranged between the anode 60 and the anode-side channel plate 50.

The cell 20 comprises a solid polymer film 21, electrodes 22, 23 (cathode 22, anode 23) and the like. Electrode 22 (23)
Are the catalyst layer 221 (231) and the gas diffusion layer 222 (232), respectively.
And the catalyst layers 221 and 231 are arranged so as to face the solid polymer film 21. In FIG. 1,
Since the catalyst layer 231 is located on the lower surface side of the solid polymer film 21, it is indicated by a broken line.

The cathode 22 of the cell 20 is connected to a gasket 40
And is superposed on the cathode-side channel plate 60 via the. The anode 23 is overlaid on the anode-side channel plate 50 via the gasket 30. The anode-side channel plate 50 is a member formed by injection-molding a mixture of phenolic resin and carbon powder. On the surface facing the gas diffusion layer 25 (the lower surface in FIG. 1), the y-direction is the longitudinal direction and the x-direction Ribs 56 are juxtaposed at regular intervals,
This allows channels to flow anode gas in the same direction
55 are formed.

The cathode-side channel plate 60 is substantially the same as the anode-side channel plate 50. Although not visible in FIG. 1, ribs are arranged at regular intervals in the x direction with the y direction as the longitudinal direction. Thus, a channel for flowing the cathode gas in the same direction is formed. further,
The solid polymer membrane 21, gaskets 30, 40, anode-side channel plate 50, and cathode-side channel plate 60 have openings at the four corners of each main surface to form internal manifolds.
61-64, 41-44, 211-214, 31-34, 51-54 (44, 21
4, 34, and 54 are not shown).
The anode gas is supplied to the channel 55 of the anode-side channel plate 50 by 1, 53, 31, 33, 211, 213, 41, 43, 61, 63. Also, the apertures 52, 54, 32, 34, 212, 21
4, 42, 44, 62, 64 cathode side channel plate 6
The cathode gas is supplied to the channel 0.

The cell unit 10 is actually a high voltage
A plurality of cells are stacked via a partition plate so that high power can be taken out, and both ends are assembled in a configuration (cell stack) in which both ends are fixed by a pair of end plates. Here, the main feature of the present embodiment lies in the configuration of the electrodes 22 and 23. Next, the configuration of the cell 20 centered on the electrodes 22 and 23 will be described in detail.

1-2. Cell Configuration The solid polymer membrane 21 is made of a fluorinated cation exchange resin such as perfluorocarbon sulfonic acid (for example, NaPont manufactured by DuPont).
on112), having a width of 7 cm in the x direction, a length of 7 cm in the y direction, and a thickness of about 50 μm in the z direction. Electrodes 22, 23
Are membrane electrodes (x
The width is 5 cm in the direction, the length in the y direction is 5 cm, and the thickness in the z direction is about 20 μm). The solid polymer film 21 is hot-pressed at the center of both main surfaces.

FIG. 2 shows the thickness direction of the cathode 22 (y
2 shows a cross-sectional view along the (z plane). The catalyst layers 221 and 231 are microporous membranes, two types of particles are mixed as shown in FIG. 2, and one of the particles is densely configured to three-dimensionally surround the other particle. . The catalyst layers 221 and 231 have pores with a diameter of about 500 nm or less as a whole. Specifically, the two types of particles are an ion exchange resin particle 221a (hereinafter, referred to as a resin particle 221a) and a catalyst-carrying carbon 221b shown in FIG. By mixing these particles, pores having a diameter of about 500 nm or less are formed in the catalyst layer 221.

The resin particles 221a are made of the same perfluorocarbon sulfonic acid as the solid polymer film 21. The resin particles 221a have a sulfonic acid group on the surface thereof,
Thereby, it exhibits hydrophilicity. On the other hand, catalyst-carrying carbon
221b has a configuration in which catalyst (here, platinum) particles 2212 are supported on porous carbon particles 2211 serving as a carrier (hereinafter, referred to as
Pt / C (platinum supported carbon) 221b
). Porous carbon particles 2211 have a specific surface area of 300 m
² / g or more, and the surface thereof is hydrophilically treated. And by this process
Pt / C 221b is provided with hydrophilicity, thereby increasing the affinity with the resin particles 221a.

Here, FIG. 3 (b) shows the resin particles 221a and Pt / C
It is an enlarged view which shows typically the vicinity part of 221b. Also figure
FIG. 7 is an enlarged view of a conventional portion (that is, a case where the porous carbon is not subjected to hydrophilic treatment) and a portion near Pt / C and the resin particles. As shown in these figures, in the present embodiment, the surface of Pt / C221b (specifically, the porous carbon particles 2211) is subjected to a hydrophilic treatment to increase the affinity with the resin particles 221a as compared with the related art. Pt / C 221b and resin particles 221a can be brought into close proximity. The affinity between such Pt / C 221b and the resin particles 221a is
It is ensured by subjecting Pt / C221b to hydrophilic treatment (electrolytic treatment). Here, by changing the intensity of the electrolytic treatment, the contact ratio of Pt / C 221b to the resin particles 221a can be adjusted. Thereby, in the present embodiment, the catalyst layer 22
In 1, the ratio of the average contact area of Pt / C221b to the resin particles 221a is set to be 40% or more.

Although the cathode 22 has been described here, the anode 23 has the same configuration in the present embodiment. The gas diffusion layers 222 and 232 are made of carbon paper impregnated with a water-repellent material (for example, polytetrafluoroethylene (PTFE)), and have the same size as the catalyst layers 221 and 231 (x direction width 5 cm × y direction length). 5 cm x thickness in the z direction about 200 μm).
These gas diffusion layers 222 and 232 ensure the flow of current between the electrodes 22 and 23 and the channel plates 50 and 60,
Also called a current collector.

1-3. Operation of Cell Unit and Effects of the Present Invention During operation of such a cell unit 10, the anode 23 side
Reformed gas (for example, hydrogen gas) and oxidized on the cathode 22 side
Each of the agent gas (for example, air) is supplied.
Thus, an electrode reaction (power generation reaction) occurs. That is, gas expansion
When the reformed gas is supplied to the catalyst layer 231 via the dispersion layer 232,
Hydrogen in gas becomes proton (H_Two→ 2H ⁺+ 2e^-), Solid
The body polymer film 21 moves to the cathode 22 side. Meanwhile, gas
An oxidant gas is supplied to the catalyst layer 221 via the diffusion layer 222
When oxygen in the gas moves through the polymer
Combines with rotone to produce water (2H⁺+ O^2-→ H_TwoO).

The solid polymer film 21 is formed by water produced by this reaction and humidified water supplied together with the reformed gas and air.
Is in a wet state, and its internal resistance is reduced to exhibit conductivity. However, conventionally, as shown in FIG. 7, if the catalyst does not easily come into contact with the ion exchange resin due to the low affinity between the ion exchange resin and the catalyst-supporting carbon in the catalyst layer, the catalyst, the ion exchange resin, and the gas layer become An inactive catalyst is generated because the contacting three-phase interface is not sufficiently secured, which causes a reduction in power generation efficiency.

On the other hand, in the present embodiment, as shown in FIG. 3B, the surface of the carbon particles 2211 is made hydrophilic, so that the affinity between the ion exchange resin and the carbon particles is higher than in the conventional case. And the catalyst easily contacts the ion exchange resin. Specifically, in the present embodiment, the average contact area of the platinum particles with the ion exchange resin in the catalyst layer is improved to 40% or more of the area of the platinum particles. Thereby, generation of the inert catalyst is drastically suppressed.

In the present embodiment, since the specific surface area of the carbon particles is 300 m ² / g or more, the catalyst particles are efficiently supported over a wide area. As a result, the three-phase interface is well secured, and excellent power generation efficiency is exhibited under the smooth electrode reaction even with the same amount of catalyst. 1-4. Manufacturing Method of Cell Here, a manufacturing method of the cell 20 will be described. Here, electrode 22
An example in which the electrode and the electrode 23 have the same configuration will be described.

1-4-1. Hydrophilic treatment of Pt / C This hydrophilic treatment is the most characteristic part of the present invention. Pt
/ C (Pt: carbon weight ratio = 30: 70, carbon carrier specific surface area; 800 m ² / g) is mixed with a lower alcohol solvent (weight ratio)
This is applied to carbon paper and filled. Next, the atmosphere is kept at room temperature under the conditions of 0.01 MPa or less, and the alcohol solution is evaporated.

Subsequently, the carbon paper with Pt / C prepared as described above is immersed in a 0.5 M sulfuric acid aqueous solution, and the electrode is subjected to a hydrophilic treatment (electrolytic treatment) by maintaining the potential at +2 V for 5 minutes with respect to the standard hydrogen electrode. . Then, after washing with ion-exchanged water, drying is performed in an atmosphere (room temperature, 0.01 MPa or less) to remove Pt / C from the carbon paper surface. Thereby, Pt / C221b whose surface has been subjected to hydrophilic treatment is obtained.

1-4-2. Preparation of Electrode A Nafion solution (5% by weight, manufactured by Aldrich Chemical Co., Ltd.) as an ion exchange resin solution was mixed with the electrolytically treated Pt / C221b (Pt / C: Nafion weight ratio). = 100: 30), and an alcohol solvent is added thereto to prepare a slurry. next,
Carbon paper (5cm × 5c)
m, thickness about 200μm) and water repellent solution (eg PTFE solution)
And dried at 380 ° C. for 1 hour to perform a water-repellent treatment. The slurry is applied to the water-repellent carbon paper by a screen printing method, and the solvent is evaporated and dried at 70 ° C. in the air. Thereby, the portion of the slurry becomes a catalyst layer, and the whole becomes a gas diffusion layer with a catalyst layer (that is, an electrode).

In this way, two sets are made to form electrodes 22 and 23 (cathode 22 and anode 23). 1-4-3. Completion of cell Prepare Nafion112 (7 cm × 7 cm, thickness of about 50 μm) manufactured by DuPont as an electrolyte membrane. Then, the cathode 22 (gas diffusion layer 222, catalyst layer 221), the electrolyte membrane 21, the anode 23 (catalyst layer 231 and gas diffusion layer 232) are laminated in this order, and integrated by hot pressing (140 ° C., 30 kg / cm ² ). I do.

Thus, the cell 20 is completed. 2. Example and Performance Evaluation Next, the example cell and the comparative example cell of the above-described embodiment were produced, and the performance was evaluated. The production method of the example cell is as described in the above 1
As described in 3. The difference between the working cell and the comparative example cell was only the presence or absence of the hydrophilic treatment for Pt / C of the catalyst layer, and the other parts were manufactured in the same manner. Several commercially available porous carbons were prepared and used as Pt / C carriers having different specific surface areas.

Regarding these working cells and comparative example cells,
Catalyst coverage (Pt in contact with resin particles in the catalyst layer
Of the catalyst layer) and the pore distribution of the catalyst layer were calculated by the following methods. 2-1.Calculation method of Pt coverage The nitrogen is supplied to the cathode of the cell, and the contact area between Pt and ion exchange resin is measured using cyclic voltammetry with the anode as the reference electrode / counter electrode and the cathode as the working electrode. did.

Here, the measured quantity of electricity (QH) in the hydrogen elimination reaction and the quantity of electricity (210 μC / cm ² ) necessary for desorbing the hydrogen atoms adsorbed per 1 cm ² of the area of the polycrystalline platinum.
Thus, the contact area (ECA) between Pt and the resin particles is determined (Equation 1). [Equation 1] ECA (cm ² ) = QH (μC) / 210 (μC / cm ² ) The higher the value of ECA, the higher the activity of the catalyst layer and the better the performance of the cell.

The surface area of Pt (the total surface area of Pt in the catalyst layer) was calculated from the weight of Pt in the catalyst and its density, assuming that the Pt particles were spherical particles having a diameter of 2.5 nm. 2-2. Measurement of pore volume of catalyst layer The pore volume of the catalyst layer was measured using a mercury porosimeter. 2-3. Experiment 1 Figure 4 shows the correlation between the specific surface area of the carbon support and the catalyst coverage for Pt / C subjected to electrolytic treatment (Example) and Pt / C not subjected to electrolytic treatment (Comparative Example). Shown in Although the figure shows the curve portion when the catalyst coverage is 60% or less, the catalyst coverage can be set higher by actually adjusting (strengthening) the degree of electrolytic treatment. .

In FIG. 4, when the carbon specific surface area was 300 m ² / g or more, the tendency of the Pt coverage increased by the electrolytic treatment was remarkably observed as shown in FIG. Thus, it is considered preferable to use carbon having a specific surface area of 300 m ² / g or more for the Pt / C of the present invention. This can be inferred as follows. That is, when the carbon specific surface area is large (specifically, 300 m ² / g or more), the unevenness of the carbon surface becomes large, so that it becomes difficult for the resin particles to come into contact with the catalyst supported on the carbon surface (that is, the resin particles are hard to contact). An active catalyst is easily generated). On the other hand, in the case of the embodiment in which the carbon is subjected to the electrolytic treatment, the resin particles easily come close to the carbon surface due to the affinity of both, and even when the carbon specific surface area is large, the contact between the Pt / C and the resin particles is large. It is considered that this has been ensured and has been advantageous for power generation.

2-4. Experiment 2 Using Pt / C having a carbon specific surface area of 800 m ² / g and 1270 m ² / g, cells having different Pt coverage by changing the strength of the electrolytic treatment (electrolytic treatment time). Was prepared. At this time, the pore volume of the catalyst layer having a diameter of 500 nm or less was set to 0.5 cc / g. The conditions of the power generation test are as follows.

Air was used as the oxidizing gas and hydrogen was used as the fuel gas. These hydrogen and air have a utilization rate of 60% and 20%, respectively.
% To the cell unit. Use a bubbler to humidify the solid polymer membrane, and set the humidification temperature to hydrogen and air respectively.
80 ° C and 76 ° C. The operating temperature of the cell unit was 80 ° C. The power generation of the cell was performed at 0.3 A / cm ² . FIG. 5 shows the correlation between the generated voltage and the catalyst coverage obtained as described above.

In this figure, it was found that, at any specific surface area of 800 m ² / g or 1270 m ² / g, when the Pt coverage exceeds 40%, a three-phase interface is particularly secured and the output is increased. From this, it can be said that it is desirable to use a catalyst having a catalyst coverage (Pt coverage) of 40% or more as Pt / C in the present invention. 2-5. Experiment 3 500 nm in the catalyst layer by changing the amount of resin particles in the catalyst layer while fixing the Pt coverage at 42% using carbon having a specific surface area of 800 m ² / g and 1270 m ² / g. The volumes of the pores having the following diameters were changed. And the air utilization rate is 20
% Was compared with the cell voltage difference (ΔV) when the air utilization was 60%.

The conditions of the power generation test in Experiment 3 were the same as those in Experiment 2.
Same as. Generally, in the catalyst layer where the gas diffusion property in the catalyst layer is not excellent, the cell voltage at a high air utilization rate (60%) is significantly lower than the cell voltage at a low air utilization rate (20%). I do. Therefore, by comparing ΔV as described above, the gas diffusivity in the catalyst layer can be evaluated (it can be seen that the smaller the value of ΔV, the better).

FIG. 6 shows the correlation between the obtained cell voltage difference ΔV and the carbon pore volume. As shown in this figure, in any specific surface area, the pore diameter 500nm
It was found that ΔV improved as the pore volume increased as follows. In particular, when the pore volume having a diameter of 500 nm or less exceeded 0.6 cc / g or less, the effect of improving ΔV was remarkably exhibited. This is considered to be because the gas diffusivity in the catalyst layer was improved by increasing the pore volume, and many three-phase interfaces were formed.

3. Other Matters In the embodiment, a cell unit having a 5 cm square electrode and a 7 cm square electrolyte membrane has been described. However, the present invention is not limited to this, and is applicable to cell units having other sizes and shapes. You may.
Further, in addition to the above embodiments, the present invention provides a solid polymer fuel cell in which only the cathode side or the anode side is humidified, or a solid polymer fuel cell in which neither the cathode side nor the anode side is humidified. May be applied.

Furthermore, in the embodiment, an example is shown in which hydrogen is used as the fuel gas and air is used as the oxidizing gas. However, the gas is not limited to these, and other gases may be used. In the above embodiments and examples, perfluorocarbon sulfonic acid (Nafi
Although an example using (on) was shown, the present invention is not limited to this, and other ion exchange resins may be used as long as they have proton conductivity.

Further, the present invention may be applied to a direct methanol fuel cell (DMFC).

[0046]

As is clear from the above, the present invention provides a porous catalyst layer comprising a carrier for supporting catalyst particles and an ion exchanger so as to contact the catalyst particles. A fuel cell electrode laminated with a gas diffusion layer,
The carrier is a porous particle made of a conductive material subjected to hydrophilic treatment having a specific surface area of 300 m ² / g or more, and of the total surface area of the catalyst particles in the catalyst layer, the surface area in contact with the ion exchanger is Since it is 40% or more, the contact between the catalyst particles and the ion exchanger becomes good, the flow of the reaction gas becomes good, the three-phase interface is secured abundantly, and power is efficiently extracted from the electrode reaction. Becomes possible. Moreover,
Since it is not necessary to increase the amount of the catalyst in order to obtain the above-mentioned effects, an effect of suppressing costs can be expected.

[Brief description of the drawings]

FIG. 1 is an assembly view showing a cell unit of a polymer electrolyte fuel cell which is an application example of the present invention.

FIG. 2 is a cross-sectional view near an electrode (cathode).

FIG. 3 is a diagram showing ion-exchange resin particles and catalyst-supporting carbon in a catalyst layer. (A) is an enlarged view of ion-exchange resin particles and catalyst-carrying carbon. (B) is an enlarged view of a portion near the ion-exchange resin particles and the catalyst-carrying carbon.

FIG. 4 is a graph showing a correlation between a carbon specific surface area and a catalyst (Pt) coverage.

FIG. 5 is a graph showing a correlation between a power generation voltage and a catalyst (Pt) coverage.

FIG. 6 is a graph showing a correlation between a cell voltage difference ΔV and a carbon pore volume.

FIG. 7 is an enlarged view of a portion near an ion exchange resin particle and a catalyst-supporting carbon in a conventional catalyst layer.

[Explanation of symbols]

 10 Cell unit 20 Cell 21 Solid polymer membrane 22 Cathode 23 Anode 221, 231 Catalyst layer 221a Ion exchange resin 221b Catalyst supported carbon 222, 232 Gas diffusion layer 2211 Carbon particles 2212 Catalyst (platinum) particles

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshito Chino 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Ikuo Yonezu 2-chome Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. F term (reference) 5H018 AA06 AS02 AS03 BB08 BB17 EE05 HH00 HH02 HH04 HH05 5H026 AA06 BB00 BB08 BB10 CC08 EE05 HH00 HH02 HH04 HH05

Claims (7)

[Claims] An electrode for a fuel cell, wherein a porous catalyst layer including a carrier supporting catalyst particles and an ion exchanger so as to contact the catalyst particles is laminated with a gas diffusion layer, The carrier is a porous particle made of a hydrophilically treated conductive material having a specific surface area of 300 m ² / g or more, and of the total surface area of the catalyst particles in the catalyst layer, the surface area in contact with the ion exchanger. The electrode for a fuel cell, characterized in that the ratio is at least 40%. 2. The conductive particles are carbon particles,
The hydrophilic treatment is an electrolytic treatment.
2. The electrode for a fuel cell according to 1. 3. The catalyst layer, wherein pores having a diameter of 500 nm or less are formed, and a pore volume corresponding to the pores having a diameter of 500 nm or less is 0.5 cc or more per 1 g of the catalyst layer. 3. The electrode for a fuel cell according to claim 1 or 2. 4. The catalyst layer, wherein pores having a diameter of 500 nm or less are formed, and a pore volume corresponding to the pores having a diameter of 500 nm or less is 0.6 cc or more per 1 g of the catalyst layer. 3. The electrode for a fuel cell according to claim 1 or 2. 5. A fuel cell, comprising the fuel cell electrode according to claim 1. A first step of supporting the catalyst particles on carbon particles as a carrier having a specific surface area of 300 m ² / g or more, and hydrophilizing the carbon particles by electrolytic treatment, and supporting the catalyst particles. The carrier, the catalyst particles, and the ion exchanger are mixed, and the surface area of the catalyst particles in contact with the ion exchanger is set to be 40% or more of the total surface area of the catalyst particles to produce a porous catalyst layer. A method for producing a fuel cell electrode, comprising: laminating the catalyst layer and the gas diffusion layer to produce a fuel cell electrode. 7. Producing an anode and / or a cathode by the method of claim 6;
A method for manufacturing a fuel cell, comprising a step of manufacturing a cell using the manufactured electrode.