JPH07201334A - Electrode for fuel cell and manufacture of the electrode - Google Patents

Abstract

PURPOSE:To heighen the cell voltage-current density, lessen the decrease of cell voltage of a terminal stage, and improve the long life properties by press- forming an electrode catalytic layer consisting of a specified catalytic powder and fluororesin. CONSTITUTION:A catalytic powder is prepared by carrying 10-40% of platinum and 15% or less ash of at least one of metal elements except platinum on 10-25% of a carbon carrier. After an electrode catalytic layer composed of the catalytic powder and 20-60% of fluororesin is immersed in an organic solvent if necessary, the organic solvent in the electrode catalytic layer is extracted and removed by applying ultrasonic wave vibration. Then, the electrode catalytic layer is heated to 50-300 deg.C and press-formed at 10-50kgf/cm<2> pressure to give a fuel electrode and/or an air electrode with 50-80% porosity and 20-45% void ratio.

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 method for producing the same, and more particularly to a catalyst layer for a fuel cell electrode such as a phosphoric acid fuel cell and a method for producing the same.

[0002]

2. Description of the Related Art A fuel cell such as a phosphoric acid fuel cell has, for example, a pair of fuel electrode and air electrode on both sides of a matrix impregnated with an electrolyte, and a pair of fuel flow channel and air flow channel on the outside thereof. A plurality of unit cells formed by arranging the porous carbon plate with ribs for storing the electrolyte are laminated to form a unit cell. Further, components such as the electrodes of the fuel electrode and the air electrode, the matrix, and the porous carbon plate with ribs for storing electrolytes are impregnated with an electrolyte such as phosphoric acid so as to facilitate the electrochemical reaction.

A conventional fuel cell will be described below by taking a phosphoric acid fuel cell as an example. In order to put the phosphoric acid fuel cell into practical use, it is important to (a) significantly reduce costs and (b) improve reliability. In order to significantly reduce the cost, for example, the power density is improved, in other words, the cell voltage-current density characteristic is improved so that the cell voltage becomes higher when the current density is increased. Need to be reduced. Further, in order to improve the reliability of the fuel cell, for example, it is necessary to improve the structure of the electrode to improve the long-term life characteristics of the cell. The cell voltage of a phosphoric acid fuel cell is practically expressed by the equation (1).

[0004]

[Equation 1]

Here, Et is the cell voltage when fuel is supplied to the fuel electrode and air is supplied to the air electrode, Eo is H _{2 to} the fuel electrode and O ₂ is supplied to the air electrode, and E _H2 is the fuel voltage. H _{2 to} the electrode, cell voltage when air is supplied to the air electrode, Eo ₂ is fuel voltage to the fuel electrode, cell voltage when O ₂ is supplied to the air electrode, I is current density, R is cell internal resistance (unit Per area), ΔH _H2 is the H ₂ gain (an index showing the gas diffusivity of the fuel electrode, the smaller the value, the better the diffusivity), ΔEo ₂ is O ₂
Gain (an index showing gas diffusivity of the air electrode, the smaller the value, the better diffusibility), and IR are voltage drops (product of current density and cell internal resistance) due to cell internal resistance.

In equation (1), the larger Eo, the more ΔE
_The smaller _H2 and ΔEo ₂ · IR, the higher the cell voltage Et. Conventionally, in order to increase Eo, the amount of platinum per unit area of the electrode catalyst layer has been increased,
Further, in order to reduce the voltage drop IR due to the H ₂ gain ΔE _H2 , the O ₂ gain ΔEo ₂ and the cell internal resistance, the thickness of the electrode catalyst layer is reduced.

FIG. 45 is an explanatory view showing the structure of a conventional electrode catalyst layer disclosed in, for example, Japanese Patent Laid-Open No. 3-37963. In the figure, the thickness L [μm] of the electrode catalyst layer in which a catalyst supporting platinum on a carbon black carrier is bound and the platinum amount D [mg / cm ² ] are represented by Cartesian coordinates (D, L). At this time, the electrode catalyst layer is configured so as to be in a region that simultaneously satisfies the following expressions (4), (5), and (6).

[0008]

[Equation 2]

However, the composition of the catalyst powder was only platinum and carbon black carrier, and the inclusion of metal elements other than platinum was not considered.

[0010]

In the electrocatalyst layer of the phosphoric acid fuel cell as described above, the electrocatalyst layer becomes too dense and the electric resistance becomes small, but the gas diffusivity is poor and the cell voltage / current density is low. Has a problem that the number of stacked cells cannot be reduced and long-term life characteristics are
There is a problem that the cell voltage is largely decreased at the end and reliability cannot be improved. Further, since the electrode catalyst layer is too dense, there is a problem in that the electrode catalyst layer is not rapidly impregnated with an electrolyte such as phosphoric acid. Furthermore, when the catalyst powder contains a metal element other than platinum, the volume ratio of the carbon black carrier, which is a conductive substance of the electrode catalyst layer, may decrease, and the electrical resistivity or the electrical resistance of the electrode catalyst layer may increase. There was a problem.

The present invention has been made to solve the above problems, and has a high cell voltage-current density characteristic, a small decrease in cell voltage at the end, and a good long-term life characteristic. The purpose is to obtain an electrode for use. It is also an object to obtain an electrode catalyst layer in which the electrolyte such as phosphoric acid is rapidly impregnated and the electric resistance value is appropriate. At the same time, it is an object to obtain a low-cost and highly reliable fuel cell electrode and a manufacturing method thereof.

[0012]

The invention according to claim 1 of the present invention comprises a matrix impregnated with an electrolyte, electrodes provided with a pair of fuel electrode and air electrode provided on both sides of the matrix, and these electrodes. In the electrode of the fuel cell formed by stacking a plurality of unit cells composed of a pair of fuel flow channel and air flow channel formed on the outer side of the electrode via a separator, At least one of the electrode catalyst layers is composed of a catalyst powder in which carbon and ash, which is one or more kinds of metal elements other than platinum, are supported on a carbon black carrier, and a fluororesin, and the volume ratio of the carbon black carrier is the electrode. 10% to 2 with respect to the catalyst layer
It is 5%.

According to the second aspect of the present invention, the porosity of the electrode catalyst layer is 50% to 80%.

The invention according to claim 3 of the present invention is such that the content of the fluororesin in the electrode catalyst layer is 20% to 60%.

The invention according to claim 4 of the present invention is such that the platinum content in the catalyst powder is 10% to 40%.

The invention according to claim 5 of the present invention is such that the ash content in the catalyst powder is 15% or less.

The invention according to claim 6 of the present invention is such that the porosity of the electrode catalyst layer is 20% to 45%.

In the invention according to claim 7 of the present invention, the carbon black carrier is heat-treated carbon having a density of 1.8 mg / cm ³ or more.

According to the eighth aspect of the present invention, the thickness of the electrode catalyst layer of the air electrode is 100 μm to 350 μm.

The invention according to claim 9 of the present invention is such that the thickness of the electrode catalyst layer of the fuel electrode is 50 μm to 250 μm.

The invention according to claim 10 of the present invention is
An electrode catalyst layer composed of a fluorocarbon resin and a catalyst powder in which carbon and ash, which is one or more kinds of metal elements other than platinum, are supported on a carbon black carrier is provided at a temperature in the range of 50 ° C to 300 ° C and 10 kgf / cm ² ~. It includes a step of press molding at a pressure in the range of 50 kgf / cm ² .

The invention according to claim 11 of the present invention is
It includes a step of immersing the electrode catalyst layer before press molding in an organic solvent, and then extracting and removing the organic solvent in the electrode catalyst layer while applying ultrasonic vibration of the electrode catalyst layer.

[0023]

According to the first aspect of the present invention, the sum of the voltage drop of the electrode catalyst layer of the air electrode and the O ₂ gain of the cell is reduced by setting the volume ratio of the carbon black carrier within a predetermined range, And increase the cell voltage.

In the second aspect of the present invention, by setting the porosity of the electrode catalyst layer within a predetermined range, the voltage drop due to electric resistance is reduced and the cell voltage is increased.

According to the third aspect of the present invention, the content of the fluororesin in the electrode catalyst layer is set within a predetermined range to reduce the sum of the voltage drop due to the electric resistance and the O ₂ gain and increase the cell voltage. To do.

According to the fourth aspect of the present invention, by setting the platinum content in the catalyst powder within a predetermined range, the sum of the voltage drop due to the electric resistance and the O ₂ gain is reduced, and the cell voltage is increased. .

In the fifth aspect of the present invention, the electrical resistivity and the electrical resistance of the electrode catalyst layer are reduced by keeping the ash content in the catalyst powder within a predetermined range.

In the sixth aspect of the present invention, the cell voltage is increased by setting the porosity of the electrode catalyst layer within a predetermined range.

According to the seventh aspect of the present invention, the density of the carbon black carrier is set within a predetermined range and the heat treated carbon carrier is used, so that the aging characteristics of the cell voltage and the O ₂ gain are improved.

In the eighth aspect of the present invention, the sum of the voltage drop due to the electric resistance and the O ₂ gain is reduced and the cell voltage is increased by setting the thickness of the air electrode within a predetermined range.

In the ninth aspect of the present invention, the sum of the voltage drop due to the electric resistance and the H ₂ gain is reduced and the cell voltage is increased by setting the thickness of the fuel electrode within a predetermined range.

In the tenth aspect of the present invention, the electrical resistivity of the electrode catalyst layer is lowered.

In the eleventh aspect of the present invention, the electrical resistivity of the electrode catalyst layer is lowered.

[0034]

EXAMPLE An electrode for a fuel cell according to the present invention comprises a matrix impregnated with an electrolyte, a pair of electrodes consisting of a fuel electrode and an air electrode provided on both sides of this matrix, and a pair of electrodes formed outside these electrodes. In an electrode of a fuel cell formed by stacking a plurality of unit cells composed of a fuel flow path and an air flow path via a separator, at least one electrode catalyst layer of the fuel electrode and the air electrode is made of carbon. It is composed of a fluorocarbon resin and a catalyst powder in which ash, which is one or more kinds of metal elements other than platinum, is supported on a black carrier.

The volume ratio of the carbon black carrier is
It is 10% to 25% (more preferably 15% to 20%) with respect to the electrode catalyst layer. Thereby, the distribution of each composition of the electrode catalyst layer is optimized, and a fuel cell having a high cell voltage-current density characteristic and a long-term life characteristic with a small decrease in the cell voltage at the end can be obtained. The electrode catalyst layer in the present invention is composed of platinum, ash, heat-treated carbon black carrier, fluororesin and pores. Here, considering the unit volume of the electrode catalyst layer, the volume of the electrode catalyst layer is the volume of platinum +
Volume of ash + volume of heat-treated carbon black carrier + fluororesin + volume of pores.

Hereinafter, the definition will be made as follows. The volume ratio of the heat-treated carbon black carrier is the volume of the heat-treated carbon black carrier / the volume of the electrode catalyst layer × 100 [%], and the porosity of the electrode catalyst layer (before the electrolyte impregnation) is (before the electrolyte impregnation of the electrode catalyst layer). ) Volume of pores / volume of electrode catalyst layer × 100
[%], The electrolyte occupancy of the electrode catalyst layer is the volume of the electrolyte (in the electrode catalyst layer) / the volume of the pores (before the electrolyte impregnation of the electrode catalyst layer) × 100 [%], the electrode (after the electrolyte impregnation) The porosity of the catalyst layer is the porosity (of the electrode catalyst layer) / 100 × (10
0- (electrolyte occupancy of electrode catalyst layer)) [%].

Considering the unit weight of the electrode catalyst layer and the catalyst powder, the weight of the electrode catalyst layer is the weight of platinum + the weight of ash + the weight of the heat-treated carbon black carrier + the weight of the fluororesin, and the weight of the catalyst powder is the weight of platinum. Weight + ash content + heat-treated carbon black carrier weight, fluororesin content is fluororesin weight / electrode catalyst layer weight x 100 [%], platinum content (platinum concentration) is platinum weight / catalyst powder Weight x 100
[%], Ash content is ash weight / catalyst powder weight × 1
It is defined as 00 [%].

The fluororesin of the electrode catalyst layer in the present invention comprises at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and the like. Is.
The ash content of the electrode catalyst layer in the present invention is made of at least one metal selected from nickel, chromium, iron, cobalt, copper and the like.

In the present invention, the volume ratio of the heat-treated carbon carrier of the electrode catalyst layer is 10 to 25% (preferably 1%).
5 to 20 [%]), and the porosity of the electrode catalyst layer is 50 to 80 [%] (preferably 60 to 70).
[%]), The fluororesin occupancy rate is 20 to 60 [%] (preferably 30 to 50 [%]), and the platinum concentration is 10 to 40.
[%] (Preferably 15 to 30 [%]), ash content is 15 [%] (preferably 10 [%]) or less, and carbon black carrier is heat-treated at a density of 1.8 [g / cm ³ ] or more. Carbon, porosity 20-45 [%] (preferably 25-40
[%]), And the thickness of the air electrode catalyst layer is 100 to 350 [μ
m] (preferably 150 to 300 [μm]), and the thickness of the fuel electrode catalyst layer is 50 to 250 [μm] (preferably 100 to
200 [μm]). As a result, the cell voltage-current density characteristics and the final characteristics of the cell voltage can be further improved, and the impregnation of the electrolyte such as phosphoric acid into the electrode catalyst layer becomes rapid.

The method for producing the electrode catalyst layer of the present invention is
The temperature of the electrode catalyst layer is 50 to 300 [° C.] and the pressure is 10 to 50.
Since it includes a step of press-molding at [kgf / cm] and immersing in an organic solvent such as acetone before heat treatment to extract and remove organic substances while applying ultrasonic vibration, the electrical resistivity of the electrode catalyst layer Therefore, the fuel cell can be provided at low cost and high reliability.

Hereinafter, the present invention will be described in more detail based on Examples 1 to 14 and Comparative Examples. Example 1. First, in order to prepare an electrode catalyst layer of an air electrode in a fuel cell, a dispersion of catalyst powder and polytetrafluoroethylene (hereinafter abbreviated as PTFE) which is a fluororesin was prepared. The catalyst powder contains 2 parts by weight of platinum.
0 [%], carbon black carrier (hereinafter abbreviated as carbon carrier) 72 [%], and ash mainly composed of nickel 8 [%] were used. In addition, the PTFE dispersion has a solid content of 60% PTFE and a dispersant of 4%.
[%] And the balance was water. As the carbon supporting platinum of the catalyst powder, graphitized carbon (hereinafter abbreviated as heat treated carbon) having a density of 1.8 [g / cm ³ ] obtained by subjecting the carrier to heat treatment at 2500 ° C. was used. An aqueous catalyst paste was prepared using this catalyst powder and PTFE.
After the catalyst paste was formed into a thin film, water was removed by drying to obtain an electrode catalyst layer. Further, this electrode catalyst layer was immersed in acetone subjected to ultrasonic vibration for 20 hours (hereinafter, simply referred to as [h]) to extract and remove most of organic substances such as a dispersant in the electrode catalyst layer and dried. And finally 360
Firing was performed at a temperature of [° C.], and then press molding was performed at room temperature of approximately 20 [° C.].

In this way, the catalyst powder / PTFE in a weight ratio is used.
= 60/40, the electrode catalyst layer of the air electrode having a weight (basis weight) of the electrode catalyst layer per unit area of 15.0 [mg / cm ² ] was prepared. By the same method, platinum is 10% by weight, catalyst powder of carbon carrier (heat treated carbon) 90% and PT
Using FE, weight ratio of catalyst powder / PTFE = 60/4
A catalyst layer of a fuel electrode having 0, a basis weight of 6.0 [mg / cm ² ] and a porosity of 65 [%] was prepared. When molding the electrode catalyst layer of the air electrode, the pressing pressure P was changed to change the volume ratio C of the carbon carrier in the electrode catalyst layer, and at this time, the porosity ε and the thickness L of the electrode catalyst body were measured. . The results are shown in FIGS. 1 and 2. Moreover, the electrical resistivity ρ and the electrical resistance Rc of the electrode catalyst layer were measured. The result is shown in FIG.

According to FIG. 1, the volume ratio C of the carbon carrier of the electrode catalyst layer changes depending on the magnitude of the pressing pressure P. The larger the pressing pressure P, the larger the volume ratio C of the carbon carrier. Further, according to FIG. 2, as the volume ratio C of the carbon carrier of the electrode catalyst layer increases,
The porosity ε and the thickness L of the electrode catalyst layer are small.
The thickness L of the electrode catalyst layer is preferably small from the viewpoint of making the cell compact, but the volume ratio C of the carbon carrier is 10
It tends to be saturated at -15% or more.

Similarly, according to FIG. 3, as the volume ratio C of the carbon carrier in the electrode catalyst layer increases, the electrical resistivity ρ and the electrical resistance Rc of the electrode catalyst layer decrease. In order to make the current distribution inside the cell uniform and suppress the Joule loss small, it is desirable that the electrical resistivity ρ be small, and in order to reduce the voltage drop IR due to the cell internal resistance R, the electrical resistance Rc is It is desirable that it is small, but it tends to be saturated when the volume ratio C of the carbon carrier is 10 to 15 [%] or more. As described above, the volume ratio C of the carbon carrier of the electrode catalyst layer is 10% (preferably 15%).
By controlling in the above range, there is an effect that the thickness L of the electrode catalyst layer, the electrical resistivity ρ, and the magnitude of the electrical resistance Rc can be optimized.

Next, carbon paper was bonded to the electrode catalyst layers of the fuel electrode and the air electrode, and the cells were assembled as the electrodes of the fuel electrode and the air electrode, respectively. The electrodes of the fuel electrode and the air electrode are provided on both sides of a matrix having a thickness of 100 μm, a porous carbon plate with ribs for electrolyte storage having a pair of fuel flow paths and air flow paths on the outside thereof, and a pair of electrodes on the outside thereof. A cell was assembled by disposing a separator plate. The matrix was impregnated with 100% of the pore volume, and the electrode and the porous carbon plate were impregnated with phosphoric acid of about 40% of the pore volume. The air electrode used was one in which the volume ratio C of the carbon carrier of the electrode catalyst layer was variously changed. The cell was operated at a temperature of 200 [° C.] by supplying fuel (H ₂ : CO ₂ = 80: 20) and air at gas utilization rates of 80 [%] and 60 [%], respectively,
After the characteristics were stabilized, the cell voltage E, the O ₂ gain ΔEo _{2 as} an index of gas diffusibility of the air electrode, and the voltage drop IRc of the electrode catalyst layer of the air electrode were measured. In both cases, the current density I is 300
It was carried out at [mA / cm ² ]. The results are shown in FIGS. 4 and 5.

According to FIG. 4, as the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode becomes larger, the voltage drop IRc of the electrode catalyst layer of the air electrode becomes smaller and the volume ratio C of the carbon carrier becomes smaller. It tends to be saturated at 10 to 15% or more. Further, as the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode increases, the O ₂ gain ΔEo ₂ of the gas diffusion index of the air electrode during cell operation increases, and the electrode catalyst layer of the air electrode The volume ratio C of the carbon carrier is 20 to 2
It tends to increase sharply above 5%. From the above, it can be seen from FIG. 4 that the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode is 10 to 25 [%] (preferably 15 to 20 [%]), which is a tentative guide as a desirable range. I understand.

FIG. 5 shows a comprehensive examination of the above relationships. According to FIG. 5, when the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode is 10 to 20 [%], the sum of the voltage drop IRc of the electrode catalyst layer of the air electrode and the O ₂ gain ΔEo ₂ of the cell is It is getting smaller. Especially, the volume ratio C of the carbon carrier is 15
In the range of -20%, the value is as small as around 120 [mv], which is preferable. Corresponding to these, the cell voltage E is high when the volume ratio C of the carbon carrier in the electrode catalyst layer of the air electrode is 10 to 25 [%]. In particular, when the volume ratio C of the carbon carrier is 15 to 20 [%], it becomes a high value of around 650 [mv], which is preferable. Further, in this range, ∂E / ∂C is small, and the cell voltage E is less susceptible to the volume ratio C of the carbon carrier.

For example, when mass-producing a phosphoric acid fuel cell, the volume ratio C of the carbon carrier in the electrode catalyst layer of the air electrode is 10 to 25% (preferably 10 to 20).
[%]), The sum of the voltage drop IRc of the electrode catalyst layer of the air electrode and the cell O ₂ gain ΔEo ₂ is small, the cell voltage E is correspondingly high, and the voltage is There is an effect that it is possible to obtain a material that is not easily influenced by the volume ratio C of the carbon carrier.

Example 2. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72 [%], and nickel-based ash content 8 [%] were used. Heat-treated carbon was used as the carbon carrier. Catalyst powder / PTFE in weight ratio
= 60/40, basis weight 6.0 [mg / cm ² ] of the electrode catalyst layer of the fuel electrode, and catalyst powder / PTFE = 60/40 by weight ratio,
An air electrode electrode catalyst layer having a basis weight of 15.0 [mg / cm ² ] was prepared. When the electrode catalyst layers of the fuel electrode and the air electrode are formed, the pressing pressure P is changed to change the porosity ε,
At this time, the volume ratio C of the carbon carrier and the electrical resistivity ρ were measured. The results are shown in FIGS. 6 and 7.

In Example 2, since the composition of the electrode catalyst layers of the fuel electrode and the air electrode is the same, the volume ratio C of the carbon carrier of the electrode catalyst layer of which the fuel electrode is the air electrode and the electrical resistivity ρ have the same value. became. Further, according to FIG. 6, the porosity ε of the electrode catalyst layer changes depending on the magnitude of the pressing pressure P. The larger the pressing pressure P, the smaller the porosity ε. Further, according to FIG. 7, the volume ratio C of the carbon carrier of the electrode catalyst layer decreases as the porosity ε of the electrode catalyst layer of the fuel electrode and the air electrode increases, and the electrical resistivity ρ of the electrode catalyst layer.
Is getting bigger. On the contrary, the electrical resistivity ρ of the electrode catalyst layer tends to be small and saturated when the porosity ε of the electrode catalyst layer is 75 to 80% or less. The volume ratio C of the carbon carrier in the electrode catalyst layer at this time is 10 to 15%.
That is all.

Carbon paper was bonded to the electrode catalyst layers of the fuel electrode and the air electrode to form electrodes of the fuel electrode and the air electrode, respectively. The fuel electrode and the air electrode were assembled into a cell under the same conditions as in Example 1, and the cell was operated. 200
After the characteristics were stabilized by operating at [° C.], the gas diffusivity was evaluated under the condition that the current density I was 300 [mA / cm ² ]. H ₂ gain ΔE _H2 which is an index of gas diffusivity of fuel electrode
And O ₂ gain ΔEo ₂ which is an index of gas diffusivity of the air electrode were measured. The results are shown in FIGS. 8 and 9, respectively.

FIG. 8 shows that the porosity ε of the electrode catalyst layer of the air electrode is constant at 65%, and the porosity ε of the electrode catalyst layer of the fuel electrode is ε.
It is when changing. As the porosity ε of the fuel cell electrode catalyst layer increases, the H ₂ gain ΔE of the cell increases.
_H2 is small, and the porosity of the fuel cell electrode catalyst layer is ε
Tends to be saturated at 50 to 55% or more. Also,
At this time, the volume ratio C of the carbon carrier of the electrode catalyst layer of the fuel electrode is about 20 to 25 [%].

Similarly, FIG. 9 shows a case where the porosity ε of the electrode catalyst layer of the fuel electrode is constant at 65%, and the porosity ε of the electrode catalyst layer of the air electrode is changed. As the porosity ε of the electrode catalyst layer of the air electrode increases, the O ₂ gain ΔEo _{2 of the} cell decreases, and the porosity ε of the electrode catalyst layer of the air electrode saturates at 50 to 55 [%] or more. There is a tendency. Further, the volume ratio C of the carbon carrier in the electrode catalyst layer of the air electrode at this time is about 20 to 25%.

The following can be said from FIGS. 7 to 9.
That is, the porosity ε of the electrode catalyst layers of the fuel electrode and the air electrode is 75 to 80 [%] or less (the volume ratio C of the carbon carrier is 1).
It is desirable that the electric resistance ρ of the electrode catalyst layer is small at 0 to 15% or more). Moreover, when the porosity ε of the electrode catalyst layer of the fuel electrode is 50 to 55 [%] or more (the volume ratio C of the carbon carrier is about 20 to 25 [%] or less), the H ₂ gain of the cell Δ
E _H2 is small, which is desirable. Furthermore, when the porosity ε of the electrode catalyst layer of the air electrode is 50 to 55 [%] or more (the volume ratio C of the carbon carrier is about 20 to 25 [%] or less), O ₂ of the cell is reduced.
Gain ΔEo ₂ is small, which is desirable.

Therefore, the porosity ε of the electrode catalyst layers of the fuel electrode and the air electrode is 50 to 80% (preferably 60 to 7).
0%) and the volume ratio C of the carbon carrier in the electrode catalyst layers of the fuel electrode and the air electrode is 10 to 25% (preferably about 15 to 20%), so that the electrode catalyst A layer having a small electric resistivity ρ and a small voltage drop due to the electric resistance can be obtained, and further the H ₂ gain ΔEo _{2 of the} cell can be obtained.
, The internal loss of the cell becomes small,
There is an effect that a cell having a high cell voltage can be obtained.

Example 3. An electrode catalyst layer was prepared in the same manner as in Example 1. That is, the composition of the raw material catalyst powder used the following in weight ratio. Heat-treated carbon was used as the carbon black carrier. Ash is a metal whose main component is nickel. Sample A is platinum 10 [%], carbon carrier 86
[%], Ash content 4 [%], sample B is platinum 20 [%], carbon carrier 72 [%], ash content 8 [%], sample C is platinum 30 [%], carbon carrier 58 [%], Ash 12
[%], Sample D is platinum 40 [%], carbon carrier 44
[%] And ash content 16 [%] are included. Catalyst powder / P by weight ratio
An electrode catalyst layer of an air electrode having TFE = 60/40 and a basis weight of 15.0 [mg / cm ² ] was prepared. The porosity ε of these electrode catalyst layers was changed, and the volume ratio C of the carbon carrier and the electrical resistivity ρ of the electrode catalyst layers at this time were measured. The result is shown in Figure 1.
0 and FIG.

According to FIG. 10, as the porosity ε of the electrocatalyst layer of the air electrode increases, the electric resistivity ρ of the electrode catalyst layer increases, and the degree of the increase is the platinum concentration of the raw material catalyst powder. The more remarkable it is. On the other hand, according to FIG. 11, the electrical resistivity ρ of the electrode catalyst layer decreases as the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode increases, but the effect of the platinum concentration of the raw material catalyst powder is shown. It can be represented by a single curve with almost no effect. By considering the display format according to FIG. 11, that is, the influence of the electrical resistivity ρ on the volume ratio C of the carbon carrier of the electrode catalyst layer,
This has the effect of making it easy to estimate the electrical resistance of the electrode catalyst layer and further the voltage drop due to the electrical resistance of the electrode.

Carbon paper was bonded to the electrode catalyst layers of these air electrodes to form air electrode electrodes. Furthermore, Example 1
Using the fuel electrode and the air electrode prepared in 1. above, a cell was assembled under the same conditions as in Example 1 and the cell was operated. 200
After the characteristics were stabilized by operating at [° C.], the gas diffusivity was evaluated under the condition that the current density I was 300 [mA / cm ² ]. O ₂ gain ΔEo ₂ which is an index of gas diffusivity of the air electrode
Was measured. The result is shown in FIG. According to FIG. 12, as the porosity ε of the electrode catalyst layer of the air electrode increases, the O ₂ gain ΔEo _{2 of the} cell decreases, but it is not so much affected by the platinum concentration of the raw material catalyst powder, Roughly 1
It is distributed around the curve of the book.

Therefore, referring to FIG. 11, the volume ratio C of the carbon carrier in the electrode catalyst layer is 10% or more (preferably 1%).
5 [%] or more), the electrical resistivity ρ can be reduced, and from FIG. 12, the porosity ε of the electrode catalyst layer is set to 5
By selecting 0% or more (preferably 60% or more), the cell O ₂ gain ΔEo ₂ can be reduced, and by combining both, the electrical resistivity ρ and the cell O ₂ gain can be reduced. A synergistic effect can be obtained in which both ΔEo ₂ can be reduced.

Example 4. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon carrier. Catalyst powder / PTFE in weight ratio
= 100/0 to 40/60 and the amount of platinum is 1.8 [m
[g / cm ² ] An air electrode electrode catalyst layer having a porosity ε of 65 [%] was prepared. In the case of catalyst powder / PTFE = 60/40,
The basis weight of the electrode catalyst layer is 15 [mg / cm ² ]. The volume ratio C, the thickness L, the electrical resistivity ρ, and the electrical resistance Rc of the carbon carrier of this electrode catalyst layer were measured. The result is shown in FIG.
And shown in FIG.

According to FIG. 13, P of the electrode catalyst layer of the air electrode
As the TFE content [%] (weight ratio) increases,
The volume ratio C of the carbon support is small, while the thickness L of the electrode catalyst layer is large. Further, when the PTFE content is about 20 to 60%, the volume ratio C of the carbon support is about 10 to 25%. According to FIG. 14, as the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode increases, the electrical resistivity ρ and the electric resistance Rc of the electrode catalyst layer decrease, and the volume ratio C of the carbon carrier is 15 It tends to be saturated at about 20% or more. Carbon paper was bonded to the electrode catalyst layers of these air electrodes to form air electrode electrodes.

Further, using the fuel electrode prepared in Example 1 and the air electrode, a cell was assembled under the same conditions as in Example 1 and the cell was operated. The cell voltage E, the O ₂ gain ΔEo ₂ which is an index of the gas diffusivity of the air electrode, and the air when the current density I is 300 [mA / cm ² ] after the characteristics are stabilized by operating at 200 [° C.] The voltage drop IRc of the electrode catalyst layer of the pole was measured. The results are shown in FIGS. 15 and 16. Figure 15
According to the above, as the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode becomes larger, the voltage drop IRc of the electrode catalyst layer of the air electrode becomes smaller, and the volume ratio C of the carbon carrier becomes about 10 to 15 [%]. Above, it tends to be saturated. Further, as the volume ratio C of the carbon support of the electrode catalyst layer of the air electrode increases, the O ₂ gain ΔEo ₂ of the gas diffusion index of the air electrode during cell operation increases, and the carbon support of the electrode catalyst layer of the air electrode increases. When the volume ratio C is about 20 to 25% or more, it tends to increase rapidly.

From the above, it can be seen from FIG. 15 that the volume ratio C of the carbon carrier in the electrode catalyst layer of the air electrode is preferably about 10 to 25%, and more preferably about 15 to 20%. FIG. 16 shows a comprehensive examination of the above relationships. According to FIG. 16, when the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode is about 10 to 25%, the sum of the voltage drop IRc of the electrode catalyst layer of the air electrode and the O ₂ gain ΔEo ₂ of the cell is small. Has become. In particular, when the volume ratio C of the carbon carrier is about 15 to 20 [%], a small value of around 110 [mv] is preferable. Corresponding to the above, the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode is 10 to 25 [%].
The cell voltage is high. Particularly, when the volume ratio C of the carbon carrier is about 15 to 20 [%], a high value of about 650 [mv] is preferable.

Therefore, by controlling the volume ratio C of the carbon carrier of the electrode catalyst layer of the air electrode within the range of about 10 to 25% (preferably about 15 to 20%), the electrode catalyst of the air electrode can be obtained. Layer voltage drop IRc and cell O ₂
There is an effect that the sum of the gains ΔEo ₂ is small and the cell voltage E can be correspondingly increased. Specifically, referring to FIG. 13, the PTFE content (weight ratio) of the electrode catalyst layer of the air electrode is about 20 to 60% (preferably 30).
The volume ratio C of the carbon carrier is controlled within the range of about 10 to 25 [%] (preferably about 15 to 20 [%]), and the above effects are obtained. To be

For example, when mass-producing a phosphoric acid fuel cell, the volume ratio C of the carbon carrier in the electrode catalyst layer of the air electrode is about 10 to 25% (preferably 15 to 2).
The PTF of the electrode catalyst layer should be in the range of 0%).
Controlling the E content has the effect of producing a cell with a high cell voltage and a small variation even if the PTFE content varies slightly during the production of the electrode catalyst layer.

Example 5. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon carrier. Catalyst powder / PTFE in weight ratio
= 60/40, the porosity ε was 65 [%], and the volume ratio C of the carbon support was 19.3 [%]. It was produced by changing the thickness L of the electrode catalyst layer to 50 to 400 [μm]. Carbon paper was bonded to the electrode catalyst layers of these air electrodes to form air electrode electrodes. Further, using the fuel electrode prepared in Example 1 and the air electrode, Example 1 was used.
The cell was assembled under the same conditions as above and the cell was operated. Two
The cell voltage E, the O ₂ gain ΔEo ₂ which is an index of gas diffusivity of the air electrode, and the air electrode when the current density I is 300 [mA / cm ² ] after the characteristics are stabilized by operating at 00 [° C.] The voltage drop IRc of the electrode catalyst layer was measured. The result is shown in FIG.
18 and FIG.

A method of increasing the amount of platinum by increasing the thickness of the electrode catalyst layer in order to increase the cell voltage has been conventionally known. 17 and 18 correspond to this. According to FIG. 17, the voltage drop IRc of the electrode catalyst layer of the air electrode increases in proportion to the thickness L of the electrode catalyst layer of the air electrode. On the other hand, the O ₂ gain ΔEo ₂ of the cell sharply increases when the thickness L of the electrode catalyst layer is 300 to 350 [μm] or more. FIG. 18 shows a comprehensive examination of the above relationships.
According to FIG. 18, the thickness L of the electrode catalyst layer of the air electrode is 300.
The sum of the voltage drop IRc of the electrode catalyst layer of the air electrode and the O ₂ gain ΔEo ₂ of the cell sharply increases at ˜350 [μm] or more. It is expected to increase the cell voltage by increasing the thickness of the electrode catalyst layer of the air electrode, but for the above reason, the cell voltage is 100% when the thickness L of the electrode catalyst layer of the air electrode is 100.
It rises in the range of about 350 [μm]. In particular,
The thickness L of the electrode catalyst layer of the air electrode is 150 to 300 [μm]
In a range of about 650 [mv], it is a high value, which is preferable.

Therefore, the thickness L of the electrode catalyst layer of the air electrode
About 100 to 350 [μm] (preferably 150 to 3)
By controlling in the range of about 00 [μm], a cell having a high cell voltage can be obtained, and the effect of the present invention can be further enhanced. Further, by optimizing the required amount of the catalyst in the electrode catalyst layer of the air electrode, it is not necessary to use the catalyst, and there is an effect that the cost of the cell can be reduced.

Example 6. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon carrier. Catalyst powder / PTFE in weight ratio
= 60/40, basis weight 15.0 [mg / cm ² ], porosity ε is 6
5 [%], carbon carrier volume ratio C is 19.3 [%]
The electrode catalyst layer of the air electrode was prepared. Carbon paper was bonded to the electrode catalyst layer of the air electrode to form an electrode of the air electrode.
Similarly, by weight ratio, catalyst powder / PTFE = 60 /
40, the porosity ε was 65%, and the volume ratio C of the carbon support was 19.3%.
It was produced by changing the thickness L of the electrode catalyst layer to 30 to 350 [μm]. Carbon paper was bonded to the electrode catalyst layers of these fuel electrodes to prepare electrodes of the fuel electrode.

Further, using the above fuel electrode and air electrode, a cell was assembled under the same conditions as in Example 1 and the cell was operated. H ₂ gain ΔE _H2 which is an index of gas diffusivity of the fuel electrode and the electrode catalyst layer of the fuel electrode when the current density I is 300 [mA / cm ² ] after the characteristics are stabilized by operating at 200 [° C.] The voltage drop IRc was measured. The results are shown in FIGS. 19 and 20. In order to increase the cell voltage, a method of increasing the amount of platinum by increasing the thickness of the electrode catalyst layer has been conventionally known. 19 and 20 correspond to this. According to FIG. 19, the voltage drop IRc of the electrode catalyst layer of the fuel electrode increases in proportion to the thickness L of the electrode catalyst layer of the fuel electrode. On the other hand, the H ₂ gain ΔE _H2 of the cell rapidly increases when the thickness L of the electrode catalyst layer is 200 to 250 [μm] or more.

FIG. 20 shows a comprehensive examination of the above relationships.
Is. According to FIG. 20, the thickness L of the electrode catalyst layer of the fuel electrode
Of 200 to 250 [μm] or more, the sum of the voltage drop IRc of the electrode catalyst layer of the fuel electrode and the H ₂ gain ΔE _H2 of the cell sharply increases. It is expected to increase the cell voltage by increasing the thickness of the electrode catalyst layer of the fuel electrode, but for the above reason, the cell voltage is 50- It is high in the range of about 250 [μm]. In particular, the thickness L of the electrode catalyst layer of the fuel electrode is 100 to 200 [μ
In the range of about m], a high value around 650 [mv] is preferable. Therefore, the thickness L of the electrode catalyst layer of the fuel electrode is about 50 to 250 [μm] (preferably 100 to 2 [μm]).
By controlling in the range of about 00 [μm], a cell having a high cell voltage can be obtained, and the effect of the present invention can be further enhanced. Further, by optimizing the required amount of the catalyst in the electrode catalyst layer of the fuel electrode, it becomes unnecessary to use the catalyst, which has the effect of contributing to the cost reduction of the cell.

Example 7. Seven types of electrode catalyst layers were prepared in the same manner as in Example 1. The following catalyst powders were used in terms of composition weight ratio. The platinum concentration is 5 to 50 [%]. Heat-treated carbon was used as the carbon carrier. Ash is a metal whose main component is nickel. Sample E is platinum 5
[%], Carbon carrier 93 [%], ash content 2 [%], sample F is platinum 10 [%], carbon carrier 86 [%], ash content 4 [%], sample G is platinum 15 [%], carbon carrier 7
9 [%], ash 6 [%], sample H is platinum 20 [%],
Carbon carrier 72 [%], ash content 8 [%], Sample I is platinum 30 [%], carbon carrier 58 [%], ash content 12
[%], Sample J is platinum 40 [%], carbon carrier 44
[%], Ash content 16 [%], sample K contains platinum 50 [%], carbon carrier 30 [%], and ash content 20 [%].

Catalyst powder / PTFE = 60/4 by weight ratio
An electrode catalyst layer for an air electrode having a weight of 0 and a basis weight of 15.0 [mg / cm ² ] was prepared. The porosity ε of these electrode catalyst layers was changed, and the electrical resistivity ρ and the electrical resistance Rc of the electrode catalyst layers at this time were measured. The results are shown in FIGS. 21 and 22. Figure 21
According to the above, as the platinum concentration of the catalyst powder in the electrode catalyst layer of the air electrode increases, the electrical resistivity ρ of the electrode catalyst layer increases, and the degree increases as the porosity ε increases. When the platinum concentration of the catalyst powder is 40% or more, the electric resistivity ρ of the electrode catalyst layer tends to increase rapidly.

Further, according to FIG. 22, as the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode increases, the electric resistance Rc of the electrode catalyst layer of the air electrode increases, and the degree thereof is the porosity ε. The larger is the larger. When the platinum concentration of the catalyst powder is about 30 to 40% or more, the electric resistance Rc of the electrode catalyst layer tends to rapidly increase. Therefore, when the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode is in the range of about 40 [%] or less (preferably about 30 [%] or less), the electrical resistivity ρ and the electrical conductivity of the electrode catalyst layer can be reduced. Since the resistance Rc can be made small, the current distribution inside the cell can be made uniform, the Joule loss can be suppressed small, and the effect of the present invention can be further enhanced.

Further, by optimizing the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode, it is possible to eliminate the waste of using a catalyst having a high platinum concentration higher than necessary at a high cost and to contribute to the cost reduction of the cell. is there. Of these electrode catalyst layers of the air electrode, carbon paper was bonded to one having a porosity ε of 65 [%] to form an electrode of the air electrode. Further, using the fuel electrode prepared in Example 1 and the air electrode, a cell was assembled under the same conditions as in Example 1 and the cell was operated. 200
The current density I is 30 after the characteristics are stabilized by operating at [° C].
In the state of 0 [mA / cm ² ], the cell voltage E, the O ₂ gain ΔEo _2, which is an index of the gas diffusibility of the air electrode, and the voltage drop IRc of the electrode catalyst layer of the air electrode were measured. The results are shown in FIGS. 23 and 24.

According to FIG. 23, as the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode increases, the voltage drop IRc of the electrode catalyst layer of the air electrode increases, and the platinum concentration of the catalyst powder becomes 30 to 40 [. %] And above, there is a tendency for a sharp increase. Further, as the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode increases, the O ₂ gain ΔEo ₂ of the gas diffusivity index of the air electrode during cell operation increases, and the catalyst of the electrode catalyst layer of the air electrode When the platinum concentration of the powder is about 30 to 40% or more, it tends to rapidly increase. From the above, from FIG. 23, the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode was 40%.
It can be seen that it is desirable that the amount is not more than about 30%, preferably not more than 30%.

FIG. 24 shows a comprehensive examination of the above relationships.
Is. According to FIG. 24, the sum of the voltage drop IRc of the electrode catalyst layer of the air electrode and the O ₂ gain ΔEo ₂ of the cell rapidly increases when the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode is about 30 to 40% or more. is doing. Corresponding to the above, the cell voltage is high when the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode is about 30 to 40% or less. The platinum concentration of the catalyst powder is 10
Below about [%], the cell voltage is low because the amount of platinum in the electrode catalyst layer is small. It is expected that the concentration of platinum in the catalyst powder of the electrode catalyst layer of the air electrode will be increased to increase the cell voltage, but for the above reason, the cell voltage is the platinum of the catalyst powder of the electrode catalyst layer of the air electrode. Concentration is 10
It becomes high in the range of about 40 [%]. Particularly, the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode is 15 to 30.
In the range of about [%], a high value around 650 [mv] is preferable.

Therefore, the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode is about 10-40% (preferably 1%).
By setting it in the range of 5 to 30 [%], a cell having a high cell voltage can be obtained, and the effect of the present invention can be further enhanced. Further, by optimizing the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode, it is not necessary to use a catalyst having a high platinum concentration higher than necessary at a high cost, and it is possible to contribute to the cost reduction of the cell.

Example 8. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon carrier. Catalyst powder / PTFE in weight ratio
= 100/0 to 10/90 and the amount of platinum is 1.8 [m
g / cm ² ], an electrode catalyst layer of the air electrode was prepared. Catalyst powder /
When PTFE = 60/40, the basis weight of the electrode catalyst layer is 1
5 [mg / cm ² ] and the porosity ε is 65 [%],
The volume ratio of the carbon carrier is 19.3 [%]. The porosity ε of these electrode catalyst layers was changed, and the electrical resistivity ρ of the electrode catalyst layer and the thickness L of the electrode catalyst layer at this time were measured. The results are shown in FIGS.

According to FIG. 25, P of the electrode catalyst layer of the air electrode is
As the TFE content increases, the electrical resistivity ρ of the electrode catalyst layer increases, and the degree increases as the porosity ε increases. The PTFE content of the electrode catalyst layer is 5
The electric resistivity ρ of the electrode catalyst layer tends to sharply increase at about 0 to 60% or more. Further, according to FIG. 26, as the PTFE content of the electrode catalyst layer of the air electrode increases, the thickness L of the electrode catalyst layer increases, and the degree thereof increases as the porosity ε increases. When the PTFE content of the electrode catalyst layer is about 50 to 60 [%] or more, the thickness L of the electrode catalyst layer tends to rapidly increase.

Further, according to FIG. 27, the electrical resistance Rc of the electrode catalyst layer increases as the PTFE content of the electrode catalyst layer of the air electrode increases, and the degree increases as the porosity ε increases. . When the PTFE content of the electrode catalyst layer is about 50 to 60% or more, the electric resistance Rc of the electrode catalyst layer tends to remarkably increase. According to FIGS. 28 to 30, as the porosity ε of the electrode catalyst layer of the air electrode increases, the electrical resistivity ρ of the electrode catalyst layer, the thickness L of the electrode catalyst layer, and the electrical resistance Rc of the electrode catalyst layer increase. The higher the PTFE content of the electrode catalyst layer, the greater the degree. When the porosity ε of the electrode catalyst layer is about 70 to 75 [%] or more, the electrical resistivity ρ of the electrode catalyst layer, the thickness L of the electrode catalyst layer, and the electrical resistance Rc of the electrode catalyst layer tend to increase rapidly.

Therefore, the PTF of the electrode catalyst layer of the air electrode is
Since the E content is about 60 [%] or less (preferably about 50 [%]) or less and the porosity ε is about 70 [%] or less, the electrical resistivity ρ of the electrode catalyst layer can be reduced,
The current distribution inside the cell can be made uniform, the Joule loss can be suppressed small, and the effect of the present invention can be further enhanced. In addition, the PTFE content of the electrode catalyst layer of the air electrode is 60 [%].
Porosity ε of 7 or less (preferably about 50%)
By setting it to about 0% or less, the thickness L of the electrode catalyst layer can be reduced, which can contribute to the compactness of the cell and the fuel cell stack.

Further, by setting the PTFE content of the electrode catalyst layer of the air electrode to about 60 [%] or less (preferably about 50 [%]) and the porosity ε to about 70 [%] or less,
There is an effect that the electric resistance Rc of the electrode catalyst layer and its voltage drop IRc can be reduced. The PT of the electrode catalyst layer of the air electrode
The lower limit of the FE content is shown in FIG.
From 6 it is desirable to be about 20 [%] (preferably about 30 [%]) or more. Although PTFE has been described as an example of the fluororesin, the same effect can be obtained even if the fluororesin is a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkylvinylether copolymer, or the like. Of course.

Example 9. Eight kinds of electrode catalyst layers were prepared in the same manner as in Example 1. The following catalyst powders were used in terms of composition weight ratio. The platinum concentration was 20%, the ash was a metal whose main component was nickel, and the carbon carrier was heat-treated carbon. Sample L is platinum 20 [%], carbon carrier 80 [%], ash 0 [%], sample M is platinum 2
0 [%], carbon carrier 76 [%], ash 4 [%],
Sample N is platinum 20 [%], carbon carrier 72 [%], ash content 8 [%], sample O is platinum 20 [%], carbon carrier 68 [%], ash content 12 [%], sample P is platinum 20.
[%], Carbon carrier 64 [%], ash content 16 [%], sample Q is platinum 20 [%], carbon carrier 60 [%], ash content 20 [%], sample R is platinum 20 [%], carbon carrier 5
6 [%], ash content 24 [%], sample S is platinum 20 [%],
It contains a carbon carrier 52 [%] and an ash content 28 [%].

Catalyst powder / PTFE = 60/4 by weight ratio
0, basis weight 15.0 [mg / cm ² ], platinum amount 1.8 [mg / cm ² ]
The electrode catalyst layer of the air electrode was prepared. The porosity ε of these electrode catalyst layers was changed, and the electrical resistivity ρ and the electrical resistance Rc of the electrode catalyst layers at this time were measured. The result is shown in FIG.
And shown in FIG. According to FIG. 31, as the ash content of the electrode catalyst layer of the air electrode increases, the electrical resistivity ρ of the electrode catalyst layer increases, and the degree increases as the porosity ε increases. The ash content of the electrode catalyst layer is 10
The electric resistivity ρ of the electrode catalyst layer tends to rapidly increase at about 15% or more. Further, according to FIG. 32, as the ash content of the electrode catalyst layer of the air electrode increases, the electric resistance Rc of the electrode catalyst layer increases, and the degree increases as the porosity ε increases. Electric resistance R of the electrode catalyst layer when the ash content of the electrode catalyst layer is about 10 to 15% or more
c tends to increase sharply.

Therefore, by setting the ash content of the electrode catalyst layer of the air electrode to about 15% (preferably about 10%) or less, the electrical resistivity ρ of the electrode catalyst layer can be reduced, and The current distribution can be made uniform, the Joule loss can be suppressed small, and the effect of the present invention can be further enhanced. In addition, the ash content of the electrode catalyst layer of the air electrode is 15
By setting it to about [%] (preferably about 10 [%]) or less, the electric resistance Rc of the electrode catalyst layer and further the voltage drop IRc of the electrode catalyst layer can be reduced. In addition,
In this embodiment, the case where nickel is used as the ash has been described, but it goes without saying that the same effect can be obtained even if the ash is chromium, iron, cobalt, copper, or an alloy thereof.

Comparative Example For comparison, an electrode catalyst layer was prepared by a conventional technique using the configuration diagram of the conventional electrode catalyst layer shown in FIG. Figure 4
The specifications were determined so that it would be almost in the center of the shaded area shown in FIG. In FIG. 44, the platinum concentration (platinum loading cost, weight ratio) of the catalyst powder is 30 [%], the PTFE content (weight ratio) of the electrode catalyst layer is 50 [%], and the platinum amount of the electrode catalyst layer is 2.
The thickness was 7 [mg / cm ² ] and the thickness was 110 [μm]. Comparative Example A. The catalyst powder used was 30% by weight of platinum, 58% by weight of carbon carrier, and 12% by weight of ash containing nickel as a main component. Heat-treated carbon was used as the carbon carrier. The volume ratio of the produced electrode catalyst layer was as follows.

[0088]

[Table 1]

The porosity ε is 33.6 [%], the electrical resistivity ρ
Was 1.04 [Ωcm]. Comparative Example B. The catalyst powder used was 30% by weight of platinum, 70% by weight of a carbon carrier, and contained no ash.
Heat-treated carbon was used as the carbon carrier. The volume ratio of the produced electrode catalyst layer was as follows.

[0090]

[Table 2]

Porosity ε is 29.3 [%], electrical resistivity ρ
Was 0.68 [Ωcm]. As described above, in Comparative Examples A and B, the porosity ε of the electrode catalyst layer produced by the conventional technique was very small and was about 30 [%] regardless of the presence or absence of ash in the electrode catalyst layer. Further, the electrical resistivity ρ was higher than that of the electrode catalyst layer containing no ash.

Example 10. An electrode catalyst layer was prepared by the method of the present invention for comparison with the comparative example. Specifications are Examples 1-9
From the result of, I decided as follows. Set the platinum concentration of the catalyst powder to 2
0 [%], the PTFE content (weight ratio) of the electrode catalyst layer is 4
0%, the amount of platinum in the electrode catalyst layer was 1.8 [mg / cm ² ] and the thickness was 185 [μm]. The catalyst powder used was 20% by weight of platinum, 72% by weight of a carbon support, and 8% by weight of ash containing nickel as a main component. Heat-treated carbon was used as the carbon carrier. The volume ratio of the produced electrode catalyst layer was as follows.

[0093]

[Table 3]

In this embodiment, the basis weight is 15.0 [mg / c
m ² ], porosity ε is 64.7 [%], and electrical resistivity ρ is 2.0.
It was 7 [Ωcm]. The electric resistivity ρ of the present example was slightly higher than that of the comparative example, but the porosity ε was about double. Carbon paper was bonded to the electrode catalyst layer of the air electrode of this example and Comparative Example A to form an electrode of the air electrode.
Furthermore, using the fuel electrode prepared in Example 1 and the above-mentioned two types of air electrodes, a cell was assembled under the same conditions as in Example 1 and the cell was operated. Before assembling the cell, phosphoric acid was applied to the above-mentioned two types of electrode catalyst layers of the air electrode and the electrode catalyst layer of the fuel electrode. About 40% of the pore volume of each electrocatalyst layer is phosphoric acid.
The amount occupying [%] was applied. Concentration of phosphoric acid is about 10
0% and a temperature of about 120 ° C. were applied.

After the application of phosphoric acid, the impregnation of the electrode catalyst layer of the fuel electrode was completed in about 1 [h]. Further, the impregnation of the electrode catalyst layer produced according to this example was completed in about 2 [h], but the electrode catalyst layer produced according to Comparative example A required a time of 20 [h] or more for impregnation. This is because the electrode catalyst layer prepared according to Comparative Example A has a high PTFE content of 50%, a high water repellent property, a small porosity of 33.6%, and is dense and hard to be impregnated with phosphoric acid. It is due to the fact. On the other hand, the electrode catalyst layer produced according to this example has a PTFE content of 40.
[%] And proper water repellent property, porosity 64.7 [%]
This is because the impregnation with phosphoric acid was completed in a short time. Current density I is 300 [mA / cm at 200 [℃]
² ], the cell voltage-current density characteristics were taken after about 2500 [h] operation. Furthermore, the current density I is 300 [mA / cm
In state ^2, the cell voltage of the two cells operated continuously - operating time characteristics and O ₂ gain - were evaluated operating time characteristics. These results are shown in FIGS.

FIG. 33 shows the fuel (H ₂ : CO ₂ = 80: 2).
0) and the gas utilization rate of air are 80% and 6 respectively.
The cell voltage-current density characteristics were taken while adjusting to 0 [%], and the cell electrode having an electrode catalyst layer prepared in Comparative Example A had a high cell voltage at a low current density and a high current density. Is low. In addition, the cell manufactured in this example has a low cell voltage at a low current density and a high cell voltage at a high current density. This is because the amount of platinum in the electrode catalyst layer of the air electrode was 2.7 [mg / cm ² ] in the case where the electrode electrode layer of the cell air electrode was prepared according to Comparative Example A, and the cell voltage was high at a low current density. Since the porosity is as low as 33.6 [%] and the gas diffusibility is poor, the cell voltage is low at high current density. On the other hand, in the case where the electrode catalyst layer was produced according to this example, the amount of platinum in the electrode catalyst layer of the air electrode was as small as 1.8 [mg / cm ² ], so the cell voltage was low at low current density, but the porosity was low. 64.7
The cell voltage is high at high current densities because it has a high [%] and good gas diffusibility.

According to FIG. 34, the electrode catalyst layer of the air electrode of the cell prepared by Comparative Example A had a higher cell voltage at the initial stage of operation as compared with the one prepared by this Example, but the cell voltage was about 2%.
After 000 [h], it reverses and becomes low, and the aging characteristics of the cell voltage thereafter deteriorate. On the other hand, in the case where the electrode catalyst layer was produced in this example, the cell voltage was slightly low at the initial stage of operation, but it showed extremely stable aging characteristics after about 2000 [h]. Corresponding to these, according to FIG. 35, in the case where the electrode catalyst layer of the air electrode of the cell was manufactured by Comparative Example A, the O ₂ gain, which is an index of the gas diffusibility of the air electrode, increased with time. . On the other hand, in the case where the electrode catalyst layer was manufactured in this example, the O ₂ gain, which is an index of the gas diffusibility of the air electrode, does not increase with time. Therefore, since the structure in the electrode catalyst layer is optimized by using the electrode catalyst layer of the air electrode produced according to this example, the cell voltage-current density characteristic is improved and the index of the gas diffusion property of the air electrode is obtained. That is, there is an effect that the increase of O ₂ gain is small with time.

Example 11. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon carrier. Catalyst powder / PTFE in weight ratio
= 60/40, basis weight 15 [mg / cm ^2], porosity of about 90
[%] Was prepared. This electrode catalyst layer is divided into five,
Press molded. The temperature of the press is 20 [℃] to 300
I prepared something that can be changed to [℃]. A spacer shim is placed around the electrode catalyst layer so that the porosity ε and the volume ratio C of the carbon carrier in the finished size of the electrode catalyst layer are the planned values, and the respective electrode catalyst layers are made into 20, 50, 100, 20
Press molding was performed under 5 conditions of 0 and 300 [° C.]. The press pressure was adjusted within the range of 10 to 100 [kgf / cm ² ].

For example, a press temperature of 20 [° C] is 100 [kgf / cm ² ] and a press temperature of 50 [° C] is 50 [kgf / c.
m ² ], 100 [℃] is 30 [kgf / cm ² ], 200
Those having a temperature of [° C.] were pressed at a surface pressure of 20 [kgf / cm ² ] and those having a temperature of 300 [° C.] of about 10 [kgf / cm ² ] for 5 minutes, respectively, and press-molded. After confirming that the porosity ε of the electrode catalyst layer after press molding and the volume ratio C of the carbon support were in agreement with the planned values, the electrical resistivity ρ was measured. The result is shown in FIG. According to FIG. 36, the electrode catalyst layer is 50 to 3
Press molding at a temperature of 00 [° C.] is smaller than that at room temperature where the electrical resistivity ρ of the electrode catalyst layer is about 20 [° C.] although the volume ratio C of the carbon support is the same. Has become.

It is considered that this is because when the press molding temperature is raised to room temperature or higher, the PTFE in the electrode catalyst layer is apt to flow during the press molding, which causes a difference in the behavior of the PTFE. As described above, the pressure for pressing the electrode catalyst layer is set to 1 by pressing the electrode catalyst layer at a temperature of room temperature or higher, for example, a temperature of 50 to 300 [° C.].
The electrical resistivity ρ of the electrode catalyst layer can be reduced under the condition that the volume ratio C of the carbon support and the porosity ε are constant, while being able to be lowered to 0 to 50 [kgf / cm ² ]. Can be increased.

Example 12. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. However, two types of carbon carriers were used: heat-treated carbon and non-heat-treated carbon (abbreviated as non-heat-treated carbon). Catalyst powder / PTFE = 60/40 by weight ratio, basis weight 1
5 [mg / cm ² ] and a porosity of about 65 [%] were prepared. Carbon paper was bonded to this type of electrode catalyst layer to form an air electrode. Furthermore, using the fuel electrode prepared in Example 1 and the above-mentioned two types of air electrodes, a cell was assembled under the same conditions as in Example 1 and the cell was operated. Approximately 10,000 [h] at a current density I of 300 [mA / cm ² ] at 200 [° C]
It was operated, and the change with time of the cell voltage E was measured.

As shown in FIG. 37, when the heat-treated carbon was used as the carbon carrier of the electrode catalyst layer of the air electrode, the initial 6
50 [mv], rising to 660 [mv] on the way, and final 655
[Mv], initial 660 using non-heat treated carbon
[Mv], the final was about 600 [mv]. Further, for reference, as shown in Figure 38, the middle cell O ₂ gain ΔE
The change in o ₂ with time was measured. Before this operation test and after the operation test, the thickness L of the electrode catalyst layer of the air electrode of the cell, the electrical resistivity ρ, and the electrical resistance Rc were measured. These results are shown in FIG.
9-shown in FIG.

When the weight loss of the carbon support was analyzed before and after the operation test, there was almost no weight loss when the heat-treated carbon was used as the carbon support of the electrode catalyst layer of the air electrode, but the weight loss when the non-heat-treated carbon was used was found. 25%
The amount was reduced as described above, and the volume ratio C of the carbon support was reduced. This is because non-heat-treated carbon is more likely to be corroded and lost during cell operation than heat-treated carbon.
Therefore, as shown in FIG. 39, in the case where the heat-treated carbon is used for the carbon carrier of the electrode catalyst layer of the air electrode, the thickness L of the electrode catalyst layer is substantially constant before and after the operation test, whereas the non-heat-treated carbon is used. The thickness L of the electrode catalyst layer was 2
It has become thin near 0 [%]. This means that the occupation ratio of phosphoric acid occupies the pores of the electrode catalyst layer substantially increases and the gas diffusivity decreases, and as shown in FIG. 37 and FIG. This causes the increase of the O ₂ gain ΔEo ₂ which is an index of the gas diffusivity of the pole.

According to FIG. 40, the one using heat-treated carbon as the carbon carrier of the electrode catalyst layer of the air electrode has a substantially constant electric resistivity ρ of the electrode catalyst layer before and after the operation test, while the one without heat treatment. In the case of using carbon, the electric resistivity ρ before the operation test is high, and after the operation test, it is even higher. The same applies to the electric resistance Rc of the electrode catalyst layer in FIG. In order to effectively bring out the effects of the present invention, the internal structure and physical properties of the electrode catalyst layer represented by the volume ratio C of the carbon support of the electrode catalyst layer of the cell before operation, the porosity ε, the electrical resistivity ρ, etc. It is important that it does not change significantly over time during operation. Therefore, in this example, by using heat-treated carbon as the carbon support of the electrode catalyst layer and suppressing the loss due to the corrosion of the carbon support during cell operation, it is possible to reduce the change over time in the internal structure and physical properties of the electrode catalyst layer. Therefore, changes with time of the cell voltage E and the O ₂ gain ΔEo ₂ are improved, and the effect of the present invention can be further enhanced.

Example 13. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon black carrier. Catalyst powder / PTFE = 60/40, basis weight 15 [mg /
cm ² ]. Organic electrode additives such as a dispersant were added to the electrode catalyst layer during the manufacturing process, so the effects of these substances were examined. First, two types were prepared, one that was washed with acetone and the other that was not washed before heat treatment of the electrode catalyst layer. Acetone was washed by immersing the electrode catalyst layer in acetone for 20 [h] and applying ultrasonic vibration to the acetone.

After the final firing at about 360 ° C., the electrical resistivity ρ of the above-mentioned two kinds of electrode catalyst layers was measured. The result is shown in FIG. 42. Further, the weight and volume of the carbon carrier decreased to about 70% of the acetone-washed product that had not been washed with acetone before the heat treatment during the production of the electrode catalyst layer. On the other hand, the grammage washed with acetone was as planned. According to FIG. 42, the electrical resistivity ρ of the electrode not washed with acetone during the preparation of the electrode catalyst layer is about 1 to 2 [Ωcm] higher than that of the electrode washed with acetone.

This is because when the electrode catalyst layer was not washed with acetone during its preparation, platinum contained in the electrode catalyst layer reacted with the organic additive at the time of final firing, so that part of the carbon carrier disappeared. This is because it was made. On the other hand, in the case of washing with acetone, since the amount of the remaining organic additive is reduced, the disappearance of the carbon carrier is suppressed by the heat treatment such as final firing, so that the volume ratio C of the electrode catalyst layer is Has been maintained greatly. In order to bring out the effect of the present invention, it is important to realize the internal structure of the electrode catalyst layer as planned. Therefore, in this example, before the heat treatment during the production of the electrode catalyst layer, the washing with acetone was performed to reduce the residual amount of the organic additive in the electrode catalyst layer, and the volume ratio C of the carbon carrier in the electrode catalyst layer was reduced. Since the proper state can be maintained, the effect of the present invention can be further enhanced. Although acetone was used in this example, it goes without saying that other organic solvents can be used.

Example 14. An electrode catalyst layer was produced in the same manner as in Example 1. As in Example 2, the catalyst powder used was 20% by weight of platinum, 72% by weight of a carbon support, and 8% by weight of ash containing nickel as a main component. Heat-treated carbon was used as the carbon carrier. The catalyst powder / PTFE = 60/40 by weight ratio, the electrode catalyst layer of the fuel electrode having a basis weight of 6.0 [mg / cm ² ], and the catalyst powder / PTFE = weight ratio.
An electrode catalyst layer of an air electrode having a weight ratio of 60/40 and a basis weight of 15.0 [mg / cm ² ] was prepared. The electrode catalyst layers of the fuel electrode and the air electrode were made to have a porosity ε of 65% and bonded to carbon paper to form electrodes of a fuel electrode and an air electrode, respectively.

Further, the cell was assembled under the same conditions as in Example 1 and the cell was operated. However, the phosphoric acid coating amount of the electrode catalyst layer of the air electrode was changed so that the phosphoric acid occupancy of the electrode catalyst layer of the air electrode was 10 to 90 [%]. Temperature 200
After operating at [° C.] and current density I of 300 [mA / cm ² ] and the characteristics became stable, the gas utilization rate of fuel (H ₂ : CO ₂ = 80: 20) and air was 80 [%] respectively. , And 60
While adjusting to [%], the current density I is 100 to 800 [mA
/ Cm ² ], and the cell voltage E at that time was measured. This is shown in FIG. If the phosphoric acid occupancy rate is too small, phosphoric acid will be insufficient, and if it is too large, gas diffusion will deteriorate, and this is reflected in the cell voltage. According to FIG. 43,
The phosphoric acid occupancy of the electrode catalyst layer of the air electrode is 30 to 70 [%].
In the range of, the cell voltage is high. Especially, phosphoric acid occupancy is 40
In the range of up to 60%, the cell voltage shows the maximum value, which is preferable. FIG. 44 shows the porosity instead of the phosphoric acid occupancy.

According to FIG. 44, the cell voltage is high when the porosity of the electrode catalyst layer of the air electrode after impregnated with phosphoric acid is in the range of 20 to 45 [%]. In particular, the cell voltage shows the maximum value in the porosity range of 25 to 40 [%], and it is necessary to have a high current density in order to reduce the cost of the fuel cell. As described above, the porosity of the electrode catalyst layer is 20 to 45 even at a high current density of 400 [mA / cm ² ] or more.
Stable load can be obtained by controlling to [%] (preferably 25 to 40 [%]), so that the effect of the present invention can be further enhanced.

In this embodiment, the air electrode has been described, but it goes without saying that it can be applied to the fuel electrode. Further, the embodiments of the present invention have been mainly described with respect to the air electrode, but needless to say, the same can be applied to the fuel electrode. Further, although platinum has been described as the catalyst metal, it is needless to say that the same can be applied to the case of containing a catalyst metal other than platinum such as palladium, rhodium, iridium, ruthenium, and osmium.

[0112]

As described above, according to the first aspect of the present invention, the matrix impregnated with the electrolyte, the electrodes composed of a pair of fuel electrode and air electrode provided on both sides of the matrix, and these electrodes are provided. At least one of the fuel electrode and the air electrode in an electrode of a fuel cell formed by stacking a plurality of unit cells composed of a pair of fuel flow path and air flow path formed outside The electrode catalyst layer comprises a catalyst powder in which carbon and ash, which is one or more kinds of metal elements other than platinum, are supported on a carbon black carrier, and a fluororesin. The volume ratio of the carbon black carrier is the electrode catalyst layer. For 10-25
Since [%] (preferably 15 to 20 [%]) is set, the cell voltage-current density characteristic and the cell voltage aging characteristic can be further enhanced, and the electrode catalyst layer is impregnated with an electrolyte such as phosphoric acid. Has the effect of being swift.
In addition, the voltage drop due to the electric resistance can be reduced and the sum of the O ₂ gains can be reduced, and the cell voltage can be increased.

According to the second aspect of the present invention, the porosity of the electrode catalyst layer is 50 to 80% (preferably 60 to 70).
[%]), The voltage drop due to electric resistance, the H ₂ gain, and the O ₂ gain are reduced, and the cell voltage can be increased.

According to the third aspect of the present invention, the content of the fluororesin in the electrode catalyst layer is 20 to 60 [%] (preferably 30).
.About.50 [%]), the sum of the voltage drop due to the electric resistance and the O ₂ gain can be reduced, and the cell voltage can be increased.

According to the fourth aspect of the present invention, the platinum (content rate) concentration of the catalyst powder of the electrode catalyst layer is set to 10 to 40 [%] (preferably 15 to 30 [%]). This has the effect of reducing the sum of the voltage drop and the O ₂ gain and increasing the cell voltage.

According to the fifth aspect of the present invention, the ash content of the catalyst powder of the electrode catalyst layer is 15 [%] (preferably 10%).
[%]) Or less, so that the electrical resistivity and the electrical resistance can be reduced.

According to the sixth aspect of the present invention, the porosity of the electrode catalyst layer is 20 to 45 [%] (preferably 25 to 40).
[%]), The cell voltage can be increased.

According to claim 7 of the present invention, the carbon black carrier of the catalyst powder of the electrode catalyst layer has a density of 1.8 [g / c].
Since the heat-treated carbon carrier of m ³ ] or more is used, there is an effect that the aging characteristics of the cell voltage and the O ₂ gain are improved.

According to the eighth aspect of the present invention, the thickness of the air electrode catalyst layer is 100 to 350 [μm] (preferably 150 to 350 μm).
Since it is set to 300 [μm], the sum of the voltage drop due to the electric resistance and the O ₂ gain can be reduced, and the cell voltage can be increased.

According to claim 9 of the present invention, the thickness of the fuel electrode catalyst layer is 50 to 250 [μm] (preferably 100 to 2).
00 [μm]), the sum of the voltage drop due to the electric resistance and the H ₂ gain can be reduced, and the cell voltage can be increased.

According to claim 10 of the present invention, the electrode catalyst layer is provided at a temperature in the range of 50 to 300 [° C.] and 10 to 50 [kgf.
/ Cm ² ], which includes a step of press-molding at a pressure of the range, the effect of lowering the electrical resistivity of the electrode catalyst layer is obtained.

Since the eleventh aspect of the present invention includes a step of immersing in an organic solvent such as acetone and applying ultrasonic vibration to extract and remove the organic matter before press molding, the electrical resistivity of the electrode catalyst layer is Therefore, it is possible to provide a highly reliable fuel cell at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a pressing pressure and a volume ratio of a carbon carrier of an electrode catalyst layer of an air electrode in Example 1 of the present invention.

FIG. 2 is a diagram showing the relationship between the volume ratio of the carbon support of the electrode catalyst layer of the air electrode and the porosity and thickness in Example 1 of the present invention.

FIG. 3 is a diagram showing the relationship between the volume ratio of the carbon support of the electrode catalyst layer of the air electrode and the electrical resistivity and the electrical resistance in Example 1 of the present invention.

FIG. 4 is a graph showing the volume ratio of the carbon carrier and the voltage drop of the electrode catalyst layer of the air electrode and the O of the cell in Example 1 of the present invention.
It is a diagram showing a relationship with _two gains.

FIG. 5 is a diagram showing the relationship between the volume ratio of the carbon carrier of the electrode catalyst layer of the air electrode and the voltage drop + cell O ₂ gain and cell voltage in Example 1 of the present invention.

FIG. 6 is a diagram showing the relationship between the press pressure and the porosity of the electrode catalyst layers of the fuel electrode and the air electrode in Example 2 of the present invention.

FIG. 7 is a diagram showing the relationship between the volume ratio of the carbon carrier in the electrode catalyst layers of the fuel electrode and the air electrode and the electrical resistivity and porosity in Example 2 of the present invention.

FIG. 8 is a diagram showing the relationship between the porosity of the electrode catalyst layer of the fuel electrode, the H ₂ gain of the cell, and the volume ratio of the carbon carrier in Example 2 of the present invention.

FIG. 9 is a diagram showing the relationship between the porosity of the electrode catalyst layer of the air electrode, the O ₂ gain of the cell, and the volume ratio of the carbon carrier in Example 2 of the present invention.

FIG. 10 is a diagram showing the relationship between the porosity and the electrical resistivity of the electrode catalyst layer of the air electrode in Example 3 of the present invention.

FIG. 11 is a diagram showing the relationship between the volume ratio of the carbon carrier in the electrode catalyst layer of the air electrode and the electrical resistivity in Example 3 of the present invention.

FIG. 12 is a diagram showing the relationship between the porosity of the electrode catalyst layer of the air electrode and the O ₂ gain of the cell in Example 3 of the present invention.

FIG. 13 is a diagram showing the relationship between the PTFE content and the thickness of the electrode catalyst layer of the air electrode in Example 4 of the present invention.

FIG. 14 is a diagram showing the relationship between the volume ratio of the carbon support of the electrode catalyst layer of the air electrode and the electrical resistivity and the electrical resistance in Example 4 of the present invention.

FIG. 15 is a diagram showing the relationship between the volume ratio of the carbon carrier of the electrode catalyst layer of the air electrode, the voltage drop, and the O ₂ gain of the cell in Example 4 of the present invention.

FIG. 16 is the volume ratio of the carbon carrier in the electrode catalyst layer of the air electrode and the voltage drop + O _{2 of the} cell in Example 4 of the present invention.
It is a diagram which shows the relationship with a gain and a cell voltage.

FIG. 17 is a diagram showing the relationship between the thickness of the electrode catalyst layer of the air electrode and the voltage drop and the O ₂ gain of the cell in Example 5 of the present invention.

FIG. 18 is a diagram showing the relationship between the thickness of the electrode catalyst layer of the air electrode and the voltage drop + cell O ₂ gain and cell voltage in Example 5 of the present invention.

FIG. 19 is a graph showing the relationship between the thickness of the electrode catalyst layer of the fuel electrode, the voltage drop, and the H ₂ gain of the cell in Example 6 of the present invention.

FIG. 20 is a diagram showing the relationship between the thickness of the electrode catalyst layer of the fuel electrode and the voltage drop + the H ₂ gain of the cell and the cell voltage in Example 6 of the present invention.

FIG. 21 is a diagram showing the relationship between the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode and the electrical resistivity in Example 7 of the present invention.

FIG. 22 is a diagram showing the relationship between the platinum concentration of the catalyst powder of the electrode catalyst layer of the air electrode and the electrical resistance in Example 7 of the present invention.

FIG. 23 is a graph showing the platinum concentration and voltage drop of the catalyst powder in the electrode catalyst layer of the air electrode and the O _{2 of the} cell in Example 7 of the present invention.
It is a diagram which shows the relationship with a gain.

FIG. 24 is a diagram showing the relationship between the platinum concentration of the catalyst powder in the electrode catalyst layer of the air electrode and the voltage drop + cell O ₂ gain and cell voltage in Example 7 of the present invention.

FIG. 25 is a diagram showing the relationship between the PTFE content and the electrical resistivity of the electrode catalyst layer of the air electrode in Example 8 of the present invention.

FIG. 26 is a diagram showing the relationship between the PTFE content and the thickness of the electrode catalyst layer of the air electrode in Example 8 of the present invention.

FIG. 27 is a diagram showing the relationship between the PTFE content of the electrode catalyst layer of the air electrode and the electrical resistance in Example 8 of the present invention.

FIG. 28 is a diagram showing the relationship between the porosity and the electrical resistivity of the electrode catalyst layer of the air electrode in Example 8 of the present invention.

FIG. 29 is a diagram showing the relationship between the porosity and the thickness of the electrode catalyst layer of the air electrode in Example 8 of the present invention.

FIG. 30 is a diagram showing the relationship between the porosity of the electrode catalyst layer of the air electrode and the electrical resistance in Example 8 of the present invention.

FIG. 31 is a diagram showing the relationship between the ash content and the electrical resistivity of the electrode catalyst layer of the air electrode in Example 9 of the present invention.

FIG. 32 is a diagram showing the relationship between the ash content of the electrode catalyst layer of the air electrode and the electrical resistance in Example 9 of the present invention.

FIG. 33 is a diagram showing cell voltage-current density characteristics in Example 10 of the present invention.

FIG. 34 is a diagram showing cell voltage-operating time characteristics in Embodiment 10 of the present invention.

FIG. 35 is a diagram showing O ₂ gain-operating time characteristics of a cell in Example 10 of the present invention.

FIG. 36 is a diagram showing the relationship between the press molding temperature and the electrical resistivity of the electrode catalyst layer of the air electrode in Example 11 of the present invention.

FIG. 37 is a diagram showing cell voltage-operating time characteristics in Embodiment 12 of the present invention.

FIG. 38 is a diagram showing the O ₂ gain-operating time characteristics of the cell in Example 12 of the present invention.

FIG. 39 is a diagram showing the thickness of the electrode catalyst layer of the air electrode in Example 12 of the present invention.

FIG. 40 is a diagram showing the electric resistivity of the electrode catalyst layer of the air electrode in Example 12 of the present invention.

FIG. 41 is a diagram showing the electric resistance of the electrode catalyst layer of the air electrode in Example 12 of the present invention.

FIG. 42 is a diagram showing the relationship between the porosity and the electrical resistivity of the electrode catalyst layer of the air electrode in Example 13 of the present invention.

FIG. 43 is a graph showing the relationship between the phosphoric acid occupancy rate of the electrode catalyst layer of the air electrode and the cell voltage in Example 14 of the present invention.

FIG. 44 is a diagram showing the relationship between the cell voltage and the porosity of the electrode catalyst layer of the air electrode in Example 14 of the present invention.

FIG. 45 is a diagram showing an optimum region of platinum amount and thickness of a conventional electrode catalyst layer.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 10, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004] [Equation _{1] E = Eo- △ E H2} - △ Eo 2 -IR ( cell _{voltage) ···· (1) △ H 2} -E H2 - E (H 2 Gain) ... (2 _{) △ Ho 2 = Eo 2 -} E (O 2 gain) ... (3)

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

Here, E is the cell voltage when fuel is supplied to the fuel electrode and air is supplied to the air electrode, Eo is H _{2 to} the fuel electrode and O ₂ is supplied to the air electrode, and E _H2 is the fuel voltage. H _{2 to} the electrode, cell voltage when air is supplied to the air electrode, Eo ₂ is fuel voltage to the fuel electrode, cell voltage when O ₂ is supplied to the air electrode, I is current density, R is cell internal resistance (unit Per area), ΔH _H2 is the H ₂ gain (an index showing the gas diffusivity of the fuel electrode, the smaller the value, the better the diffusivity), ΔEo ₂ is O ₂
Gain (an index showing gas diffusivity of the air electrode, the smaller the value, the better diffusibility), and IR are voltage drops (product of current density and cell internal resistance) due to cell internal resistance.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

In equation (1), the larger Eo, the more ΔE
_H2, the cell voltage E, the higher △ Eo _2, IR is small. Conventionally, in order to increase Eo, the amount of platinum per unit area of the electrode catalyst layer has been increased,
Further, in order to reduce the voltage drop IR due to the H ₂ gain ΔE _H2 , the O ₂ gain ΔEo ₂ and the cell internal resistance, the thickness of the electrode catalyst layer is reduced.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

In the electrode catalyst layer of the phosphoric acid fuel cell and the like as described above, the electrode catalyst layer becomes too dense and the electric resistance becomes small, but the gas diffusibility is poor and the cell voltage - current density is low. Has a problem that the number of stacked cells cannot be reduced and long-term life characteristics are
Increased after time reduction of the cell voltage, there is a problem that can not be improved in reliability. Further, since the electrode catalyst layer is too dense, there is a problem in that the electrode catalyst layer is not rapidly impregnated with an electrolyte such as phosphoric acid. Further, when containing a metal element except platinum in the catalyst powder, the electrical resistivity and electric resistivity of the volume ratio of carbon black responsible <br/> body is a conductive material of the electrode catalyst layer is smaller becomes the electrode catalyst layer There is a problem that it may become large.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011] This invention has been made to solve the above problems, the cell voltage - current density characteristics is high and, after the time of cell voltage reduction is small, good fuel cell of long life characteristics The purpose is to obtain an electrode for use. It is also an object to obtain an electrode catalyst layer in which the electrolyte such as phosphoric acid is rapidly impregnated and the electric resistance value is appropriate. At the same time, it is an object to obtain a low-cost and highly reliable fuel cell electrode and a manufacturing method thereof.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

In the invention according to claim 7 of the present invention, the carbon black carrier is heat-treated carbon having a density of 1.8 g / cm ³ or more.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

The invention according to claim 11 of the present invention is
Was immersed an electrode catalyst layer before press-forming organic Solvent, then those containing a step of extracting and removing the organic material of the electrode catalyst layer while applying ultrasonic vibration of the electrode catalyst layer.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

In the second aspect of the present invention, by setting the porosity of the electrode catalyst layer within a predetermined range, the voltage drop due to the electric resistance , the H ₂ gain and the O ₂ gain are reduced.
Increase the cell voltage.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

The volume ratio of the carbon black carrier is
It is 10% to 25% (more preferably 15% to 20%) with respect to the electrode catalyst layer. Thus, it distributed proper of the composition of the electrode catalyst layer, the cell voltage - current density characteristics is high and a good fuel cell small extended life characteristics decline when after the cell voltage is obtained. The electrode catalyst layer in the present invention is composed of platinum, ash, heat-treated carbon black carrier, fluororesin and pores. Here, considering the unit volume of the electrode catalyst layer, the volume of the electrode catalyst layer is the volume of platinum +
Volume of ash + volume of heat-treated carbon black carrier + fluororesin + volume of pores.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Hereinafter, the definition will be made as follows. The volume ratio of the heat-treated carbon black carrier volume × 100 [%] of the volume / electrode catalyst layer of the heat treatment of carbon black in charge <br/> body (before the electrolyte impregnation) the porosity of the electrode catalyst layer of the (electrode catalyst layer Volume of pores (before electrolyte impregnation) / volume of electrocatalyst layer × 100
[%], The electrolyte occupancy of the electrode catalyst layer is the volume of the electrolyte (in the electrode catalyst layer) / the volume of the pores (before the electrolyte impregnation of the electrode catalyst layer) × 100 [%], the electrode (after the electrolyte impregnation) The porosity of the catalyst layer is the porosity (of the electrode catalyst layer) / 100 × (10
0- (electrolyte occupancy of electrode catalyst layer)) [%].

[Procedure Amendment 12]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

Further, the unit weight of the electrode catalyst layer and the catalyst powder is
Considering this, the weight of the electrode catalyst layer is the weight of platinum + the weight of ash + heat treatment.
Carbon blackBearerBody weight + fluororesin weight, touch
The weight of the carrier powder is the weight of platinum + the weight of ash + the heat treated carbo
BlackBearerBody weight, fluororesin content is fluororesin
Weight / electrode catalyst layer weight × 100 [%], platinumconcentration
(platinumContent rate) Is the weight of platinum / the weight of catalyst powder × 100
[%], Ash content is ash weight / catalyst powder weight × 1
It is defined as 00 [%].

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

The fluororesin of the electrode catalyst layer in the present invention comprises at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and the like. Is.
The ash content of the electrode catalyst layer in the present invention is made of at least one metal selected from nickel, chromium, iron, cobalt, copper , ruthenium, palladium and the like.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

In the present invention, the volume ratio of the heat-treated carbon carrier of the electrode catalyst layer is 10 to 25% (preferably 1%).
5 to 20 [%]), and the porosity of the electrode catalyst layer is 50 to 80 [%] (preferably 60 to 70).
[%]), Fluorine resin containing Yuritsu 20-60 [%] (preferably 30 to 50 [%]), 10 to 40 platinum concentration
[%] (Preferably 15 to 30 [%]), the ash content of 15%] (preferably 10 [%]) or less, heat-treated carbon black responsible body density 1.8 [g / cm ^3] or more Carbon, porosity 20-45 [%] (preferably 25-40
[%]), And the thickness of the air electrode catalyst layer is 100 to 350 [μ
m] (preferably 150 to 300 [μm]), and the thickness of the fuel electrode catalyst layer is 50 to 250 [μm] (preferably 100 to
200 [μm]). Thus, the cell voltage - current density characteristics and makes it possible to increase the over-time characteristics of the cell voltage, impregnation of an electrolyte such as phosphoric acid to the electrode catalyst layer is quickly.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

The method for producing the electrode catalyst layer of the present invention is
The temperature of the electrode catalyst layer is 50 to 300 [° C.] and the pressure is 10 to 50.
And press-molded at [kgf / cm ^2], then immersed in an organic solvent medium such as acetone before the heat treatment, then, since to include the step of extracting and removing organic matter while applying ultrasonic vibration, the electrode catalyst layer electrically The resistivity can be lowered, and thus a low cost and highly reliable fuel cell can be provided.

[Procedure Amendment 16]

[Document name to be amended] Statement

[Correction target item name] 0041

[Correction method] Change

[Correction content]

Hereinafter, the present invention will be described in more detail based on Examples 1 to 14 and Comparative Examples. Example 1. First, in order to prepare an electrode catalyst layer of an air electrode in a fuel cell, a dispersion of catalyst powder and polytetrafluoroethylene (hereinafter abbreviated as PTFE) which is a fluororesin was prepared. The catalyst powder contains 2 parts by weight of platinum.
0 [%], carbon black responsible body (hereinafter, referred to as carbon responsible body) is 72 [%], ash mainly comprising nickel was used for 8%. In addition, the PTFE dispersion has a solid content of 60% PTFE and a dispersant of 4%.
[%] And the balance was water. Carbon, abbreviated as graphitized carbon (hereinafter heat treatment carbon density 1.8 was subjected to heat treatment at 2500 [° C.] in charge of body [g / cm ^3] of the platinum catalyst powder are responsible <br/> equity ) Was used. An aqueous catalyst paste was prepared using this catalyst powder and PTFE. After the catalyst paste was formed into a thin film, water was removed by drying to obtain an electrode catalyst layer. Further, this electrode catalyst layer was immersed in acetone subjected to ultrasonic vibration for 20 hours (hereinafter, simply referred to as [h]) to extract and remove most of organic substances such as a dispersant in the electrode catalyst layer and dried. And finally 360
Firing was performed at a temperature of [° C.], and then press molding was performed at room temperature of approximately 20 [° C.].

[Procedure Amendment 17]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

In this way, the catalyst powder / PTFE in a weight ratio is used.
= 60/40, the electrode catalyst layer of the air electrode having a weight (basis weight) of the electrode catalyst layer per unit area of 15.0 [mg / cm ² ] was prepared. In the same way, platinum 10%] by weight, the catalyst powder and PT of the carbon responsible body (heat treatment Carbon) 90 [%]
Using FE, weight ratio of catalyst powder / PTFE = 60/4
A catalyst layer of a fuel electrode having 0, a basis weight of 6.0 [mg / cm ² ] and a porosity of 65 [%] was prepared. When the electrode catalyst layer of the air electrode is molded, the pressing pressure P is changed to change the carbon in the electrode catalyst layer.
Changing the volume ratio C of the responsible body was measured porosity ε and thickness L in this case the electrode catalyst layer. The results are shown in FIGS. 1 and 2. Moreover, the electrical resistivity ρ and the electrical resistance Rc of the electrode catalyst layer were measured. The result is shown in FIG.

[Procedure 18]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

[0043] According to FIG. 1, the volume ratio C of the carbon in charge of the electrode catalyst layer is changed by the magnitude of the pressing pressure P. Volume ratio C of the larger pressing pressure P carbon responsible body also increases. Furthermore, as the volume ratio C of the carbon in charge of the electrode catalyst layer is increased according to Fig. 2,
The porosity ε and the thickness L of the electrode catalyst layer are small.
The thickness L of the electrode catalyst layer is preferably smaller in terms of compactness of the cell, the volume ratio C of the carbon responsible body 10
It tends to be saturated at -15% or more.

[Procedure Amendment 19]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044] According similarly to FIG. 3, as the volume ratio C of the carbon in charge of the electrode catalyst layer increases, the electrical resistivity of the electrode catalyst layer ρ and electric resistance Rc is reduced. In order to make the current distribution inside the cell uniform and suppress the Joule loss small, it is desirable that the electrical resistivity ρ be small, and in order to reduce the voltage drop IR due to the cell internal resistance R, the electrical resistance Rc is smaller is desirable, there is a tendency that the volume ratio C of the carbon responsible body is saturated at 10 to 15 [%] or more. Above, the volume ratio C of the carbon responsible <br/> of the electrode catalyst layer 10 [%] (preferably 15 [%])
By controlling in the above range, there is an effect that the thickness L of the electrode catalyst layer, the electrical resistivity ρ, and the magnitude of the electrical resistance Rc can be optimized.

[Procedure amendment 20]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

Next, carbon paper was bonded to the electrode catalyst layers of the fuel electrode and the air electrode, and the cells were assembled as the electrodes of the fuel electrode and the air electrode, respectively. The electrodes of the fuel electrode and the air electrode are provided on both sides of a matrix having a thickness of 100 μm, a porous carbon plate with ribs for electrolyte storage having a pair of fuel flow paths and air flow paths on the outside thereof, and a pair of electrodes on the outside thereof. A cell was assembled by disposing a separator plate. The matrix was impregnated with 100% of the pore volume, and the electrode and the porous carbon plate were impregnated with phosphoric acid of about 40% of the pore volume. The air electrode was used to change the volume ratio C of the carbon in charge of the electrode catalyst layer in various ways. The cell was operated at a temperature of 200 [° C.] by supplying fuel (H ₂ : CO ₂ = 80: 20) and air at gas utilization rates of 80 [%] and 60 [%], respectively,
After the characteristics were stabilized, the cell voltage E, the O ₂ gain ΔEo _{2 as} an index of gas diffusibility of the air electrode, and the voltage drop IRc of the electrode catalyst layer of the air electrode were measured. In both cases, the current density I is 300
It was carried out at [mA / cm ² ]. The results are shown in FIGS. 4 and 5.

[Procedure correction 21]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

[0046] According to FIG. 4, as the volume ratio C of the carbon in charge of the electrode catalyst layer of the air electrode is increased, the voltage drop IRc electrode catalyst layer of the air electrode is reduced, the carbon responsible <br/> body When the volume ratio C is 10 to 15 [%] or more, it tends to be saturated. Furthermore, as the volume ratio C of the carbon in charge of the electrode catalyst layer of the air electrode is increased, during cell operation O ₂ gain △ Eo ₂ gas diffusion index of the air electrode is increased, the cathode electrode catalyst layer volume ratio C of the carbon responsible body 20-2
It tends to increase sharply above 5%. From the above, to be a tentative standard of the volume ratio C is 10 to 25 [%] (preferably 15 to 20 [%]) is preferably in the range of carbon in charge of the electrode catalyst layer of the air electrode is from 4 I understand.

[Procedure correction 22]

[Document name to be amended] Statement

[Correction target item name] 0047

[Correction method] Change

[Correction content]

FIG. 5 shows a comprehensive examination of the above relationships. According to FIG. 5, O ₂ gain △ Eo voltage drop IRc and cell volume ratio C of the carbon responsible <br/> of the electrode catalyst layer of the air electrode is 10 to 20 [%] in the electrode catalyst layer of the air electrode The sum of ₂ is smaller. In particular the volume ratio C of the carbon responsible body 15
In the range of -20%, the value is as small as around 120 [mv], which is preferable. Volume ratio C of the carbon in charge of these corresponding electrode catalyst layer of the air electrode is the cell voltage E in 10 to 25 [%] is high. In particular the volume ratio C of the carbon in charge are preferred has a high value of around 15 to 20 [%] in 650 [mv]. Further, the cell voltage E has become smaller ∂E / ∂C in this range is less likely affected by the volume ratio C of the carbon responsible body.

[Procedure amendment 23]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

[0048] For example, in the case of mass production of the cell of the phosphoric acid fuel cell, the volume ratio C of the carbon in charge of the electrode catalyst layer of the air electrode 10 to 25 [%] (preferably 10 to 20
[%]), The sum of the voltage drop IRc of the electrode catalyst layer of the air electrode and the cell O ₂ gain ΔEo ₂ is small, the cell voltage E is correspondingly high, and the voltage is there is an effect that those less susceptible to volume ratio C of the carbon responsible body is obtained.

[Procedure correction 24]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

Example 2. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon responsible body 72 [%], ash mainly comprising nickel was used for 8%. Carbon responsible body was using the heat treatment carbon. Catalyst powder / PTFE in weight ratio
= 60/40, basis weight 6.0 [mg / cm ² ] of the electrode catalyst layer of the fuel electrode, and catalyst powder / PTFE = 60/40 by weight ratio,
An air electrode electrode catalyst layer having a basis weight of 15.0 [mg / cm ² ] was prepared. By changing the pressing pressure P when forming the electrode catalyst layer of the fuel electrode and the air electrode, to change the porosity epsilon, was measured volume ratio C and the electric resistivity ρ of the carbon in charge of this time . The results are shown in FIGS. 6 and 7.

[Procedure correction 25]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction content]

[0050] In the second embodiment, since the composition of the electrode catalyst layer of the fuel electrode and the air electrode are the same, the fuel electrode and the same value is the volume ratio C and the electric resistivity ρ of the carbon in charge of the electrode catalyst layer of the air electrode became. In addition, according to FIG. 6, the porosity of the electrode catalyst layer ε is changed by the magnitude of the pressing pressure P. The larger the pressing pressure P, the smaller the porosity ε. Further, according to FIG. 7, the volume ratio C of the carbon carrier of the electrode catalyst layer decreases as the porosity ε of the electrode catalyst layer of the fuel electrode and the air electrode increases, and the electrical resistivity ρ of the electrode catalyst layer.
Is getting bigger. On the contrary, the electrical resistivity ρ of the electrode catalyst layer tends to be small and saturated when the porosity ε of the electrode catalyst layer is 75 to 80% or less. The volume ratio C of the carbon carrier in the electrode catalyst layer at this time is 10 to 15%.
That is all.

[Procedure Amendment 26]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction content]

Similarly, FIG. 9 shows a case where the porosity ε of the electrode catalyst layer of the fuel electrode is constant at 65%, and the porosity ε of the electrode catalyst layer of the air electrode is changed. As the porosity ε of the electrode catalyst layer of the air electrode increases, the O ₂ gain ΔEo _{2 of the} cell decreases, and the porosity ε of the electrode catalyst layer of the air electrode saturates at 50 to 55 [%] or more. There is a tendency. The volume ratio C of the carbon responsible <br/> of the electrode catalyst layer of the air electrode at this time is 20 to 25 [%] degree.

[Procedure Amendment 27]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction content]

The following can be said from FIGS. 7 to 9.
That is, the porosity of the electrode catalyst layer of the fuel electrode and the air electrode ε is 75-80% or less (volume ratio C of the carbon responsible body 1
It is desirable that the electric resistance ρ of the electrode catalyst layer is small at 0 to 15% or more). The porosity of the electrode catalyst layer of the fuel electrode ε is 50-55% or more H ₂ gain (volume ratio C is more than about 20 to 25 [%] of carbon responsible body) cell △
E _H2 is small, which is desirable. Furthermore, the porosity of the electrode catalyst layer of the air electrode ε is 50-55% or more (volume ratio C of the carbon responsible body 20-25% of around or less) of the cell O ₂
Gain ΔEo ₂ is small, which is desirable.

[Procedure correction 28]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Change

[Correction content]

Therefore, the porosity ε of the electrode catalyst layers of the fuel electrode and the air electrode is 50 to 80% (preferably 60 to 7).
0 [%] C.) and the volume ratio C of the carbon in charge of the electrode catalyst layer of the fuel electrode and the air electrode 10 to 25 [%] (preferably by 15 to 20 [%] or so), the electrode catalyst A layer having a small electric resistivity ρ and a small voltage drop due to the electric resistance can be obtained, and further the H ₂ gain ΔEo _{2 of the} cell can be obtained.
, The internal loss of the cell becomes small,
There is an effect that a cell having a high cell voltage can be obtained.

[Procedure correction 29]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

Example 3. The electrode catalyst layer was created manufactured by the method as in Example 1. That is, the composition of the raw material catalyst powder used the following in weight ratio. Carbon black responsible body was using the heat treatment carbon. Ash is a metal whose main component is nickel. Sample A platinum 10 [%], carbon responsible 86
[%], Ash content 4%], Sample B Pt 20 [%], carbon responsible 72 [%], ash 8 [%] Sample C Pt 30 [%], carbon responsible 58 [%], Ash 12
[%], Sample D Platinum 40%, carbon responsible 44
[%] And ash content 16 [%] are included. Catalyst powder / P by weight ratio
TFE = 60/40, and the basis weight 15.0 [mg / cm ^2] create made an electrode catalyst layer of the air electrode. These electrode catalyst layer changes the porosity epsilon, was measured volume ratio C and the electric resistivity ρ of the carbon in charge of the electrode catalyst layer at this time. The result is shown in Figure 1.
0 and FIG.

[Procedure amendment 30]

[Document name to be amended] Statement

[Name of item to be corrected] 0057

[Correction method] Change

[Correction content]

According to FIG. 10, as the porosity ε of the electrocatalyst layer of the air electrode increases, the electric resistivity ρ of the electrode catalyst layer increases, and the degree of the increase is the platinum concentration of the raw material catalyst powder. The more remarkable it is. On the other hand, according to FIG. 11, the electrical resistivity of the electrode catalyst layer as the volume ratio C of the carbon in charge of the electrode catalyst layer of the air electrode increases ρ is reduced, the influence of the concentration of platinum catalyst powder of raw material It can be represented by a single curve with almost no effect. Display format according to FIG. 11, i.e., by considering the influence of the electrical resistivity ρ to volume ratio C of the carbon in charge of the electrode catalyst layer,
This has the effect of making it easy to estimate the electrical resistance of the electrode catalyst layer and further the voltage drop due to the electrical resistance of the electrode.

[Procedure correction 31]

[Document name to be amended] Statement

[Correction target item name] 0059

[Correction method] Change

[Correction content]

[0059] Thus, referring to FIG. 11, the volume ratio C of the carbon in charge of the electrode catalyst layer 10% or more (preferably 1
5 [%] or more), the electrical resistivity ρ can be reduced, and from FIG. 12, the porosity ε of the electrode catalyst layer is set to 5
By selecting 0% or more (preferably 60% or more), the cell O ₂ gain ΔEo ₂ can be reduced, and by combining both, the electrical resistivity ρ and the cell O ₂ gain can be reduced. A synergistic effect can be obtained in which both ΔEo ₂ can be reduced.

[Procedure correction 32]

[Document name to be amended] Statement

[Correction target item name] 0086

[Correction method] Change

[Correction content]

Therefore, by setting the ash content of the electrode catalyst layer of the air electrode to about 15% (preferably about 10%) or less, the electrical resistivity ρ of the electrode catalyst layer can be reduced, and The current distribution can be made uniform, the Joule loss can be suppressed small, and the effect of the present invention can be further enhanced. In addition, the ash content of the electrode catalyst layer of the air electrode is 15
By setting it to about [%] (preferably about 10 [%]) or less, the electric resistance Rc of the electrode catalyst layer and further the voltage drop IRc of the electrode catalyst layer can be reduced. In addition,
In the present embodiment, the case where nickel is used as the ash is described, but the ash is chromium, iron, cobalt, copper , ruthenium,
Of course, palladium and alloys thereof also have the same effect.

[Procedure amendment 33]

[Document name to be amended] Statement

[Correction target item name] 0087

[Correction method] Change

[Correction content]

Comparative Example For comparison, an electrode catalyst layer was prepared by a conventional technique using the configuration diagram of the conventional electrode catalyst layer shown in FIG. Figure 4
The specifications were determined so that it would be almost in the center of the shaded area shown in FIG. In FIG. 44, the platinum concentration of the catalyst powder (platinum loading
Amount (weight ratio) of 30 [%], PTFE content (weight ratio) of the electrode catalyst layer is 50 [%], and platinum amount of the electrode catalyst layer is 2.
The thickness was 7 [mg / cm ² ] and the thickness was 110 [μm]. Comparative Example A. The catalyst powder used was 30% by weight of platinum, 58% by weight of carbon carrier, and 12% by weight of ash containing nickel as a main component. Heat-treated carbon was used as the carbon carrier. The volume ratio of the produced electrode catalyst layer was as follows.

[Procedure amendment 34]

[Document name to be amended] Statement

[Correction target item name] 0095

[Correction method] Change

[Correction content]

After the application of phosphoric acid, the impregnation of the electrode catalyst layer of the fuel electrode was completed in about 1 [h]. Further, the impregnation of the electrode catalyst layer produced according to this example was completed in about 2 [h], but the electrode catalyst layer produced according to Comparative example A required a time of 20 [h] or more for impregnation. This is because the electrocatalyst layer produced in Comparative Example A had a high PTFE content of 50%, a high water repellency , and a small porosity of 33.6%, and was dense. This is because it was difficult to impregnate with phosphoric acid. On the other hand, the electrode catalyst layer produced according to this example has a PTFE content of 4
0 [%] and the water repellency is appropriate, porosity also 64.7
This is because [%] is a proper value and the impregnation of phosphoric acid was completed in a short time. Current density I is 300 at 200 [℃]
The cell voltage-current density characteristic was taken after about 2500 [h] operation in the state of [mA / cm ² ]. Further, the current density I is 300
In the state of [mA / cm ² ], the cells were continuously operated to evaluate the cell voltage-operating time characteristic and the O ₂ gain-operating time characteristic of the two types of cells. These results are shown in FIGS.

[Procedure amendment 35]

[Document name to be amended] Statement

[Correction target item name] 0096

[Correction method] Change

[Correction content]

FIG. 33 shows the fuel (H ₂ : CO ₂ = 80: 2).
0) and the gas utilization rate of air are 80% and 6 respectively.
The cell voltage-current density characteristics were taken while adjusting to 0 [%], and the cell electrode having an electrode catalyst layer prepared in Comparative Example A had a high cell voltage at a low current density and a high current density. Is low. In addition, the cell manufactured in this example has a low cell voltage at a low current density and a high cell voltage at a high current density. This is because the amount of platinum in the electrode catalyst layer of the air electrode was 2.7 [mg / cm ² ] when the electrode catalyst layer of the air electrode of the cell was prepared according to Comparative Example A, and the cell voltage was < Although it is high , the porosity is as low as 33.6 [%] and the gas diffusibility is poor, so the cell voltage is low at high current densities. On the other hand, in the case where the electrode catalyst layer was produced according to this example, the amount of platinum in the electrode catalyst layer of the air electrode was as small as 1.8 [mg / cm ² ], so the cell voltage was low at low current density, but the porosity was low. 64.7
The cell voltage is high at high current densities because it has a high [%] and good gas diffusibility.

[Procedure correction 36]

[Document name to be amended] Statement

[Correction target item name] 0104

[Correction method] Change

[Correction content]

According to FIG. 40, the one using heat-treated carbon as the carbon carrier of the electrode catalyst layer of the air electrode has a substantially constant electric resistivity ρ of the electrode catalyst layer before and after the operation test, while the one without heat treatment. In the case of using carbon, the electric resistivity ρ before the operation test is high, and after the operation test, it is even higher. The same applies to the electric resistance Rc of the electrode catalyst layer in FIG. In order to effectively bring out the effects of the present invention, the internal structure and physical properties of the electrode catalyst layer represented by the volume ratio C of the carbon support of the electrode catalyst layer of the cell before operation, the porosity ε, the electrical resistivity ρ, etc. It is important that it does not change significantly over time during operation. Thus, in this embodiment, by using a heat treatment of carbon to carbon carrier of the electrode catalyst layer, by suppressing the loss due to corrosion of the carbon support in the cell operation, it can be reduced the time course of the internal structure and properties of the electrode catalyst layer Therefore, changes with time of the cell voltage E and the O ₂ gain ΔEo ₂ are improved, and the effect of the present invention can be further enhanced.

[Procedure amendment 37]

[Document name to be amended] Statement

[Correction target item name] 0105

[Correction method] Change

[Correction content]

Example 13. An electrode catalyst layer was produced in the same manner as in Example 1. The catalyst powder contains 20 platinum by weight.
[%], Carbon carrier 72%, and nickel-based ash 8%. Heat-treated carbon was used as the carbon black carrier. Catalyst powder / PTFE = 60/40, basis weight 15 [mg /
cm ² ]. Organic electrode additives such as dispersants were added during the production of the electrode catalyst layer, so the effects thereof were examined. First, two types were prepared, one that was washed with acetone and the other that was not washed before heat treatment of the electrode catalyst layer. Acetone was washed by immersing the electrode catalyst layer in acetone for 20 [h] and then applying ultrasonic vibration to the acetone.

[Procedure amendment 38]

[Document name to be amended] Statement

[Correction target item name] 0107

[Correction method] Change

[Correction content]

This is because when the electrode catalyst layer was not washed with acetone during its preparation, platinum contained in the electrode catalyst layer reacted with the organic additive at the time of final firing, so that part of the carbon carrier disappeared. This is because it was made. On the other hand, in the case of washing with acetone, since the amount of the remaining organic additive is reduced, the disappearance of the carbon carrier is suppressed by the heat treatment such as final firing, so that the volume ratio C of the electrode catalyst layer is Has been maintained greatly. In order to bring out the effect of the present invention, it is important to realize the internal structure of the electrode catalyst layer as planned. Therefore, in this example, before the heat treatment during the production of the electrode catalyst layer, the washing with acetone was performed to reduce the residual amount of the organic additive in the electrode catalyst layer, and the volume ratio C of the carbon carrier in the electrode catalyst layer was reduced. Since the proper state can be maintained, the effect of the present invention can be further enhanced. In the present embodiment it has been using acetone, also can be used other organic Solvent of course.

[Procedure amendment 39]

[Document name to be amended] Statement

[Correction target item name] 0115

[Correction method] Change

[Correction content]

According to the fourth aspect of the present invention, the platinum concentration (content rate ) of the catalyst powder of the electrode catalyst layer is set to 10 to 40% (preferably 15 to 30%). This has the effect of reducing the sum of the voltage drop and the O ₂ gain and increasing the cell voltage.

[Procedure amendment 40]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 17

[Correction method] Change

[Correction content]

FIG. 17

[Procedure Amendment 41]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 18

[Correction method] Change

[Correction content]

FIG. 18

[Procedure amendment 42]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 20

[Correction method] Change

[Correction content]

FIG. 20

[Procedure amendment 43]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 25

[Correction method] Change

[Correction content]

FIG. 25

[Procedure correction 44]

[Document name to be corrected] Drawing

[Correction target item name]

[Correction method] Change

[Correction content]

FIG. 26

[Procedure amendment 45]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 27

[Correction method] Change

[Correction content]

FIG. 27

Claims (11)

[Claims] 1. A matrix impregnated with an electrolyte, electrodes formed of a pair of fuel electrode and air electrode provided on both sides of the matrix, and a pair of fuel flow channel and air flow channel formed outside these electrodes. In a fuel cell electrode formed by stacking a plurality of unit cells each including a separator with a separator, at least one of the fuel electrode and the air electrode has an electrode catalyst layer in which platinum and platinum are excluded from a carbon black carrier. It is composed of a catalyst powder carrying one or more kinds of metal element ash and a fluororesin, and the volume ratio of the carbon black carrier is 10% to 25% with respect to the electrode catalyst layer. Electrodes for fuel cells. 2. The porosity of the electrode catalyst layer is 50% to 80%.
The fuel cell electrode according to claim 1, wherein 3. The fluororesin content of the electrode catalyst layer is 20.
% To 60%, The fuel cell electrode according to claim 1, wherein 4. The platinum content in the catalyst powder is 10% to 4
It is 0%, The electrode for fuel cells of Claim 1 characterized by the above-mentioned. 5. The fuel cell electrode according to claim 1, wherein the ash content in the catalyst powder is 15% or less. 6. The porosity of the electrode catalyst layer is 20% to 45%.
The fuel cell electrode according to claim 1, wherein 7. The carbon black carrier has a density of 1.8.
The fuel cell electrode according to claim 1, which is heat-treated carbon of mg / cm ³ or more. 8. The thickness of the electrode catalyst layer of the air electrode is 100 μm.
The fuel cell electrode according to claim 1, wherein the electrode has a thickness of m to 350 μm. 9. The thickness of the electrode catalyst layer of the fuel electrode is 50 μm.
The electrode for a fuel cell according to claim 1, wherein the electrode has a thickness of ˜250 μm. 10. An electrode catalyst layer comprising a fluorocarbon resin and a catalyst powder in which carbon and ash, which is one or more kinds of metal elements other than platinum, are supported on a carbon black carrier, and an electrode catalyst layer at 50 ° C.
Temperature in the range of 300 ° C and 10 kgf / cm ^{2 to} 50 kgf / c
A method for producing an electrode for a fuel cell, comprising a step of press-forming at a pressure in the range of m ² . 11. The method comprises the steps of immersing the electrode catalyst layer before press molding in an organic solvent, and then extracting and removing the organic solvent in the electrode catalyst layer while applying ultrasonic vibration to the electrode catalyst layer. The method for producing a fuel cell electrode according to claim 10.