JPH10334928A - Phosphoric acid type fuel cell, manufacturing apparatus of electrode for phosphoric acid type fuel cell, and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphoric acid type fuel cell, a manufacturing apparatus of its electrode, and a manufacturing method of the electrode. SOLUTION: A cell is composed by laminating an anode electrode 2 and a cathode electrode 3, interposing an electrolyte layer between them. A catalyst layer at the electrolyte layer side of the anode electrode 2 is divided into two parts: a part at an oxidizer inlet side is a platinum catalyst layer 9 and a part at an oxidizer outlet side is a platinum catalyst layer 10. An electrolyte reservoir 4 for supplying a fuel gas is arranged at the opposite side of an electrolyte layer 1 of the anode electrode 2. An electrolyte reservoir 5 for supplying an oxidizer gas is arranged at the opposite side of an electrolyte layer side of the cathode electrode 3. A cell stack is composed by multilayered cells, and a separator 8 is inserted between the electrolyte reservoir 4 of an adjacent cell and the electrolyte reservoir 5. A cooling plate 6 is inserted every several cells of the cell stack for forming a cooling structure such that an inlet part of a cooling water at a cooling tube 7 inside a cooling plate 6 corresponds to a downstream of the oxidizer gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphoric acid type fuel cell using phosphoric acid as an electrolyte, and more particularly to a phosphoric acid side fuel cell in which electrodes are improved to extend the life and an apparatus for manufacturing the electrodes. And a manufacturing method.

[0002]

2. Description of the Related Art Fuel cells that directly generate electricity by electrochemically reacting hydrogen obtained by reforming a fuel such as natural gas with oxygen in the air vary depending on what is used as an electrolyte. Among them, a phosphoric acid type fuel cell using phosphoric acid as an electrolyte has been most developed at present. An example of this phosphoric acid fuel cell will be described below with reference to FIG. That is, the electrolyte layer 1 is impregnated with phosphoric acid as an electrolyte, and a single cell (hereinafter, referred to as a cell) is formed by sandwiching the electrolyte layer 1 between the anode electrode 2 and the cathode electrode 3. The anode electrode 2 and the cathode electrode 3 are formed on an electrode substrate made of a porous body, and on a carbon-supporting powder obtained by supporting platinum or platinum fine particles on a carbon powder as a support, a fluorocarbon resin binder Is kneaded, applied, heated and pressed to form a platinum catalyst layer.

[0003] On the surface of each of the anode electrode 2 and the cathode electrode 3 opposite to the electrolyte layer 1,
An anode-side electrolyte reservoir 4 and a cathode-side electrolyte reservoir 5 provided with a groove for allowing a reaction gas to flow therethrough are provided on this surface. Further, the cells are stacked in multiple layers to form a fuel cell stack, and a separator 8 is inserted between the electrolyte reservoir 4 on the anode side and the electrolyte reservoir 5 on the cathode side of adjacent cells. .

In the cell having the above structure, fuel gas is supplied to the grooves of the electrolyte reservoir 4 on the anode side, and oxidizing gas is supplied to the grooves of the electrolyte reservoir 5 on the cathode side. A reaction occurs between the anode electrode 2 and the cathode electrode 3 to generate power. That is, in the anode electrode 2, as shown in the following equation 1, hydrogen reacts to form hydrogen ions and electrons, and the hydrogen ions move toward the cathode electrode 3 in the electrolyte.

[0005]

H ₂ → 2H ⁺ + 2e ⁻ Equation 1 At the cathode electrode 3, as shown in the following Equation 2, the moving hydrogen ions, the electrons flowing through the external circuit, and the oxygen supplied from the outside are The following reaction takes place to produce water.

[0006]

[Number 2] _{^{O 2 + 4H + + 4e -}} → 2H 2 O ... Equation 2 Here, since the reaction at the cathode electrode 3 above is exothermic, in a typical fuel cell stack, the generated heat For removal, cooling plates 6 are inserted every few cells. The cooling plate 6 is configured by sandwiching a cooling pipe 7 through which hot water as a cooling medium passes through a carbon plate having good thermal conductivity and excellent corrosion resistance. In the following description, several cells between the cooling plates 6 are collectively called a sub-stack, and a stack of all the cells is called a battery stack.

[0007] Incidentally, in order to reduce the cost of the phosphoric acid type fuel cell, in addition to reducing the manufacturing cost,
The running cost can be reduced by extending the life. As a measure for extending the life, there are a method by reducing the rate of decrease in the voltage characteristics, a method to suppress the voltage drop during the start / stop operation, and a method to extend the retention time of phosphoric acid as an electrolyte. Among them, to extend the life of the third phosphoric acid, the means for supplying phosphoric acid that decreases with the operating time in a timely manner and the amount of phosphoric acid taken out of the battery together with the reaction gas are reduced to shorten the required life. A conventional technique described in Japanese Patent Application Laid-Open No. 4-179060 will be described below as a means for reducing the amount of phosphoric acid carried out, which is divided into means for securing phosphoric acid.

That is, in this prior art, as shown in FIG. 10, by utilizing the characteristic that the vapor pressure of phosphorus pentoxide increases with temperature, the temperature of the oxidizing gas outlet is changed from the oxidizing gas inlet to the center. By making the temperature lower than the temperature of the oxidizing gas, the vapor of phosphorus pentoxide diffused in the oxidizing gas from the oxidizing gas inlet to the center is condensed at the oxidizing gas outlet. In other words, the phosphoric acid vapor has a vapor pressure equilibrium with the temperature in the high temperature portion at the oxidizing gas inlet, and has a vapor pressure equilibrium with the temperature in the low temperature portion at the oxidizing gas outlet. Since the vapor pressure is lower in the low temperature part than in the high temperature part, the phosphoric acid vapor corresponding to the difference in the partial pressure is condensed and recovered, and the amount taken out as vapor together with the supply gas is reduced.

[0009]

In order to reduce the amount of phosphoric acid carried out as described above, the amount of phosphoric acid remaining in the battery is determined based on the amount of phosphorous pentoxide vapor discharged from the battery together with the supply gas. When the pressure is obtained, the vapor pressure is shifted upward from the relationship between the temperature and the partial pressure shown in FIG.
In other words, the actual vapor pressure of phosphoric acid at the oxidant gas outlet is
It can be seen that the supersaturated state was higher than the saturated vapor pressure determined by FIG. Therefore, from the viewpoint of the relationship between the temperature and the vapor pressure of phosphoric acid, the effect of reducing the amount of phosphoric acid brought out is that sufficient condensed amount is not obtained despite the conditions under which the condensed amount should be further increased. As inadequate.

For example, when the current density distribution and the temperature distribution in the flow direction of the oxidizing gas in the prior art shown in FIG. 9 are analyzed, as shown in FIG. The current density is large and the current density decreases at the oxidant gas outlet. As a result, the temperature is high near the oxidizing gas inlet, and the temperature decreases toward the oxidizing gas outlet. When the temperature distribution shown in FIG. 11 is applied to the electrolyte reservoir by an external heater and an oxidizing gas is flown, the concentration of phosphoric acid in the gas at the oxidizing gas outlet is determined by the relationship between the temperature and the vapor pressure shown in FIG. The concentration was higher than that (supersaturation).

The fuel gas supplied to the anode electrode 2 of the fuel cell contains 1 to 2% of carbon monoxide. However, when a platinum catalyst is used as a catalyst for the anode electrode 2, The effect of catalyst poisoning by carbon monoxide increases as the temperature decreases. For example, in the case of the fuel cell shown in FIG. 9, in the low-temperature region provided at the oxidizing gas outlet, the poisoning of the fuel gas by carbon monoxide contained in the fuel gas increases as the temperature decreases. In other words, the current density on the oxidant gas outlet side becomes smaller from the characteristics of the anode electrode 2,
As a result, the density distribution at the oxidant gas inlet becomes large,
The temperature will rise.

[0012] Therefore, in the current density distribution along the flow path of the oxidizing gas, the difference between the oxidizing gas inlet side and the oxidizing gas outlet side is further increased as shown in FIG.
As a result, the maximum value of the phosphoric acid vapor concentration increases, and as a result, the phosphoric acid vapor concentration at the oxidant gas outlet increases, so that the effect of reducing the amount of phosphoric acid carried out is not sufficient.

The present invention has been proposed to solve the problems of the prior art as described above.
By reducing the difference in current density distribution, the vapor concentration of supersaturated phosphoric acid at the outlet of the oxidizing gas is reduced, and the amount of phosphoric acid taken out of the battery together with the reaction gas is reduced. It is an object of the present invention to provide a phosphoric acid type fuel cell capable of realization, a manufacturing apparatus and a manufacturing method for the electrode thereof.

[0014]

Means for Solving the Problems To achieve the above object, the invention according to the first to fourth aspects of the present invention is directed to a method in which a plurality of single cells in which an electrolyte layer impregnated with phosphoric acid is sandwiched between a pair of anode and cathode electrodes. Laminated, a catalyst layer is formed on the surface of the anode electrode and the cathode electrode, and an electrolyte reservoir in which a groove for fuel gas supply and a groove for oxidant gas supply are formed is in a position in contact with the anode electrode and the cathode electrode, respectively. A gas-impermeable separator is inserted between the electrolyte reservoir in contact with the anode electrode and the electrolyte reservoir in contact with the cathode electrode of a unit cell adjacent thereto, and a cooling plate is provided for each of the plurality of unit cells. The phosphoric acid fuel cell in which is inserted has the following technical features.

That is, according to the first aspect of the present invention, a cooling medium is provided in the cooling plate so as to be able to flow so that the oxidizing gas outlet side is in a low temperature range, and the oxidizing gas in the catalyst layer of the anode electrode is provided. The portion corresponding to the outlet portion is formed of a platinum-based transition noble metal alloy catalyst.

According to the first aspect of the present invention, a platinum-based transition noble metal alloy resistant to poisoning with carbon monoxide is formed on the oxidant outlet side, which is a low temperature region in the anode electrode. Compared with the case of the catalyst, the difference in the current density distribution in the electrode plane is reduced, the temperature difference can be reduced, and the maximum temperature is reduced. As a result, the maximum value of the concentration of phosphoric acid vapor in the oxidizing gas is reduced, so that the concentration of phosphoric acid vapor at the outlet of the oxidizing gas is reduced, and the amount of phosphoric acid taken out of the battery as vapor together with the oxidizing gas is reduced. And the battery life is prolonged.

According to a second aspect of the present invention, in the first aspect of the present invention, a region where the catalyst layer is not formed is provided in a portion of the cathode electrode corresponding to the oxidant gas outlet. Features. According to the second aspect of the present invention, since a region where no catalyst is formed is provided on the oxidizing gas outlet side of the cathode electrode, heat generation at the oxidizing gas outlet is forcibly suppressed. You. As a result, the oxidant gas outlet becomes a region having the lowest temperature in the plane of the battery, and the amount of phosphoric acid condensed can be increased, so that the amount of phosphoric acid carried out can be further reduced.

According to a third aspect of the present invention, there is provided the phosphoric acid type fuel cell according to the first or second aspect, wherein the platinum-based alloy catalyst layer on the side of the oxidizing gas outlet formed on the anode electrode and the oxidizing gas. The boundary with the catalyst layer on the inlet side is provided at a position closer to the oxidizing gas outlet in a unit cell far from the cooling plate than in a unit cell close to the cooling plate. .

In the third aspect of the present invention, the position of the boundary of the catalyst at the anode electrode of the unit cell far from the cooling plate (high temperature) is close to the cooling plate (low temperature).
The catalyst is formed at a position closer to the oxidant outlet than the boundary of the catalyst at the anode electrode of the unit cell, so that each catalyst has a minimum difference between the voltage characteristics of the platinum catalyst electrode and the voltage characteristics of the alloy catalyst. And the current density can be made more uniform in all the cells. Therefore, the difference in the current density distribution is reduced, the temperature difference can be reduced, and the maximum temperature is reduced. As a result, the maximum value of the concentration of phosphoric acid vapor in the oxidizing gas is reduced, so that the concentration of phosphoric acid vapor at the outlet of the oxidizing gas is reduced, and the amount of phosphoric acid taken out of the battery as vapor together with the oxidizing gas is reduced. As a result, the battery life is prolonged.

According to a fourth aspect of the present invention, in the phosphoric acid fuel cell according to any one of the first to third aspects, ruthenium or palladium is used as a transition noble metal which is a component of the alloy catalyst layer. It is characterized by being. According to the invention as described above, by using ruthenium or palladium for the alloy catalyst layer, an electrode having excellent temperature characteristics can be formed, the difference in current density can be reduced, and the temperature difference in the battery plane direction can be reduced. , The concentration of phosphorus diffused in the oxidizing gas is reduced, and a longer battery life can be achieved.

According to a fifth aspect of the present invention, there is provided a phosphoric acid type fuel cell electrode manufacturing apparatus for forming a catalyst layer by spraying a catalyst powder on an electrode substrate of a phosphoric acid type fuel cell. It has such technical features.

That is, the invention according to claim 5 provides a platinum catalyst pipe for guiding the platinum catalyst powder and an alloy catalyst pipe for guiding the alloy catalyst powder at the top of the quadrangular pyramid-shaped catalyst powder covering the electrode substrate. Are separately connected to each other, and a separation plate for separating the platinum catalyst powder introduced from the platinum catalyst pipe and the alloy catalyst powder introduced from the alloy catalyst pipe is provided inside the catalyst powder cover. It is characterized by having.

According to the fifth aspect of the present invention, the electrode substrate is covered with a catalyst cover, a platinum catalyst material is charged from a platinum catalyst pipe, and an alloy catalyst material is charged from an alloy catalyst pipe. Since the platinum catalyst and the alloy catalyst can be formed at once, the anode electrode can be easily and efficiently manufactured. In addition, since the catalyst layer can be uniformly formed on the electrode substrate, a reliable electrode having stable characteristics for a long time can be manufactured.

According to a sixth aspect of the present invention, in the apparatus for manufacturing an electrode for a phosphoric acid type fuel cell according to the fifth aspect, a mechanism is provided in which an angle of the separation plate with respect to a vertical direction is variable. . According to the sixth aspect of the present invention, it is possible to easily manufacture electrodes having different positions of the boundary between the platinum catalyst layer and the alloy catalyst layer with one apparatus, so that the manufacturing efficiency is further improved and the manufacturing cost is reduced. Reduction can be achieved.

According to a seventh aspect of the present invention, in the apparatus for manufacturing an electrode for a phosphoric acid fuel cell according to the fifth or sixth aspect, the lower end of the separation plate is located above the bottom surface of the catalyst powder cover. It is characterized by. In the invention according to claim 7 described above, since the lower end of the separation plate does not contact the substrate, formation of a groove at the boundary between the platinum catalyst layer and the alloy catalyst layer is prevented, and the thickness of the catalyst layer is made uniform. And an electrode having more excellent characteristics can be manufactured.

Further, according to the present invention, there is provided a phosphoric acid type fuel cell in which a platinum-based transition noble metal alloy catalyst layer is formed in a portion of the catalyst layer of an anode electrode of a fuel cell corresponding to an oxidant gas outlet. In the method for producing an electrode for an electrode, after the catalyst layer on the oxidant gas inlet side and the alloy catalyst layer on the oxidant gas outlet side are each formed in a sheet shape, the sheets of the two kinds of catalyst layers are respectively formed on the anode electrode. A catalyst layer is formed on the anode electrode by arranging them on a substrate, stacking an electrolyte layer on the two kinds of catalyst layer sheets, and pressing them together. According to the eighth aspect of the present invention, since the catalyst layer can be formed on the electrode substrate together with the pressure bonding of the electrolyte layer, the yield in forming the catalyst layer is improved.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

(1) First Embodiment One embodiment corresponding to the invention described in claim 1 will be described below as a first embodiment with reference to FIG.
FIG. 1 is an exploded perspective view showing the configuration of the present embodiment.

(Configuration) First, the configuration of the present embodiment will be described. That is, a cell is formed by stacking the anode electrode 2 and the cathode electrode 3 with the electrolyte layer 1 interposed therebetween. A catalyst layer is formed on the surface of the anode electrode 2 on the electrolyte layer side (the back surface of the anode electrode 2 in FIG. 1). In this catalyst layer, the platinum catalyst layer 9 coated with the platinum catalyst described in the prior art is provided on the oxidant gas inlet side, and the alloy catalyst coated with a platinum-based transition metal alloy catalyst is provided on the oxidant gas outlet side. The layer 10 is formed.

On the opposite side of the anode electrode 2 from the electrolyte layer 1 (on the front side of the anode electrode 2 in FIG. 1), an electrolyte reverser 4 for supplying fuel gas to the electrode 2 is arranged. An electrolyte reservoir 5 for supplying an oxidizing gas to the cathode electrode 3 is arranged on the side opposite to the layer (on the back side of the cathode electrode 3 in FIG. 1). The cells are stacked in multiple layers to form a battery stack, and between the anode-side electrolyte reservoir 4 and the cathode-side electrolyte reservoir 5 of an adjacent cell, a gas-impermeable material containing carbon as a main component is provided. Conductive separator 8
Is inserted. Furthermore, in the battery stack,
A cooling plate 6 having a cooling pipe 7 is inserted every several cells, and the inlet of the cooling water supplied to the cooling pipe 7 has a cooling water supply structure corresponding to the downstream side of the oxidizing gas.

(Operation and Effect) The operation and effect of the present embodiment having the above configuration are as follows. That is,
Since the temperature of the cooling water flowing through the cooling pipe 7 receives the heat generated by the battery in the course of the flow, the temperature rises from the oxidizing gas outlet to the oxidizing gas inlet in the drawing. I do. Also, the oxygen concentration of the oxidizing gas is consumed in the power generation reaction, and therefore decreases as going from the oxidizing gas inlet side to the oxidizing gas outlet side. It decreases as going from the agent gas inlet to the oxidant gas outlet. That is, the calorific value decreases as going from the oxidizing gas inlet to the oxidizing gas outlet. As a result, the oxidant gas outlet is a region having the lowest temperature in the plane of the battery.

Since the alloy catalyst layer 10 is applied to the anode electrode 2 corresponding to the low-temperature region of the oxidizing gas outlet, poisoning by carbon monoxide on the oxidizing gas outlet side is suppressed. In addition, the current is prevented from being concentrated on the oxidant gas inlet side and the temperature is prevented from rising. Therefore, since the amount of phosphoric acid that goes out of the battery is reduced, the life of the battery is prolonged.

In the battery having the above-described temperature distribution and the basic structure as in the present embodiment, the amount of phosphoric acid taken out together with the oxidizing gas is affected by the maximum temperature in the plane of the battery. The higher the value, the more phosphoric acid is taken out. However, in the present embodiment, as described above, the temperature rise due to the current being concentrated on the oxidant gas inlet side is suppressed, so that the maximum temperature is suppressed and the amount of phosphoric acid taken out can be reduced. .

(2) Second Embodiment One embodiment corresponding to the invention described in claim 2 will be described below as a second embodiment with reference to FIG. FIG. 2 is an exploded perspective view showing the configuration of the present embodiment.

(Configuration) First, the configuration of the present embodiment will be described. That is, in the present embodiment, the basic configuration is the first
A platinum catalyst layer 9 is formed on the oxidant gas inlet side of the surface of the anode electrode 2 on the electrolyte layer side (the back surface of the anode electrode 2 in FIG. 1), and the oxidant gas outlet side The alloy catalyst layer 10 is formed on the substrate. Further, a catalyst layer is usually also formed on the surface of the cathode electrode 3 on the side of the electrolyte layer (the surface of the cathode electrode 3 in FIG. 2). An area 11 where the catalyst is not applied is provided.

(Operation and Effect) The operation and effect of the present embodiment having the above configuration are as follows. That is,
In the present embodiment, a platinum catalyst layer 9 is applied to the oxidant gas inlet side of the anode electrode 2 and an alloy catalyst layer is applied to the oxidant gas outlet side, as in the first embodiment. Since 10 is applied, the current can be prevented from being concentrated on the oxidant gas inlet side and the temperature can be prevented from rising, the amount of phosphoric acid going out of the battery can be reduced, and the life of the battery can be prolonged. Further, the maximum temperature is suppressed, and the amount of phosphoric acid taken out can be reduced.

Further, in this embodiment, since the region 11 where the catalyst is not applied is provided on the cathode electrode 3 on the side of the oxidizing gas outlet, heat generation at the oxidizing gas outlet is forcibly suppressed. You. As a result, the oxidant gas outlet becomes the lowest temperature area in the battery plane,
Since the amount of phosphoric acid condensed can be increased, the amount of phosphoric acid taken out can be further reduced.

(3) Third Embodiment One embodiment corresponding to the invention described in claim 3 will be described below as a third embodiment with reference to FIGS. FIG. 3 is an exploded perspective view showing the configuration of the present embodiment, and FIGS. 4 and 5 are graphs showing differences in battery voltage characteristics depending on the temperature between a battery using a platinum catalyst and a battery using an alloy catalyst. FIG.

(Configuration) First, the configuration of the present embodiment will be described. That is, in the present embodiment, as shown in FIG. 3, five cells 12 to 16 are stacked between the cooling plates 6 to form a substack. Each cell 12-1
Reference numeral 6 denotes a unit cell in which an electrolyte layer is sandwiched between a cathode electrode and an anode electrode. As in the above-described embodiment, an electrolyte reservoir and a separator (not shown) are stacked.

Then, the cells 12 constituting the substack
16 to 16, the anode electrode 2 in the uppermost cell and the lowermost cell 12 in contact with the cooling plate 6 and the cell 16 is provided with an alloy catalyst layer 10 coated with an alloy catalyst over the entire surface.
The anode electrode 2 of the middle cell 14 is provided with a platinum catalyst layer 9 coated with a platinum catalyst in an area 2/3 from the oxidant gas inlet side, and an alloy catalyst in the remaining area 1/3. The alloy catalyst layer 10 coated with is provided. Further, the cells 13 and 15 sandwich the cell 14 from above and below.
The anode electrode 2 is provided with a platinum catalyst layer 9 coated with a platinum catalyst in one third of the area from the oxidant gas inlet side, and an alloy catalyst layer 10 coated with an alloy catalyst in the remaining 2/3 of the area.
Is provided.

(Operation and Effect) The operation and effect of the present embodiment having the above configuration are as follows. First, in a typical phosphoric acid fuel cell substack, FIG.
As shown in (2), the difference between the characteristics of the platinum catalyst electrode and the characteristics of the alloy catalyst electrode increases as the temperature decreases. here,
In FIG. 4, the temperature range A indicates the temperature difference in the plane of the cell far from the cooling plate, and the temperature range B indicates the temperature difference in the plane of the cell in contact with the cooling plate. From these characteristics, the temperature range A in the figure
In order to share the platinum catalyst and the alloy catalyst so that the current density becomes more uniform in each of the catalysts, each catalyst must be so arranged that the difference between the voltage characteristics of the platinum catalyst electrode and the voltage characteristics of the alloy catalyst is minimized in the temperature range A. All you have to do is share.

More specifically, in the temperature range A, if the platinum catalyst is applied to the range A1 in FIG. 4 and the alloy catalyst is applied to the temperature range A2, the difference between the characteristics can be obtained by the voltage Va in FIG. To Vb. On the other hand, in the temperature range B, the platinum catalyst is applied to the temperature range B1 and the alloy catalyst is applied to the temperature range B2, so that the difference in the voltage characteristics falls within the range of the voltage Vc to Vd. As can be seen from FIG.
Comparing the position of the boundary between A1 and A2 in the temperature range A with the position of the boundary between B1 and B2 in the temperature range B,
The position of the boundary between A1 and A2 has a larger bias toward the low temperature side.

In the present embodiment, the alloy catalyst layer 10 is formed on the entire surface of the anode electrode 2 of the cell 12 and the cell 16 in contact with the cooling plate 6, and as the distance from the cooling plate 6 increases, 13 to 14 and cell 15
To 14, the platinum catalyst layer 9 and the alloy catalyst layer 1
The boundary with 0 is formed so as to be close to the oxidant gas outlet side (low temperature side). Here, the in-plane temperature range and the temperature characteristic of each cell have a relationship as shown in FIG. 5, and each of the cells 12 to 16 of the present embodiment has the cooling plate 6 as described above.
(C-a), the boundary between the alloy catalyst layer 10 and the platinum catalyst layer 9 is configured to be biased toward the lower temperature side, so that the difference in current density in the plane of each cell is minimized. Become. In FIG. 5, a1 and b1 indicate the application range of the platinum catalyst layer 9, and a2 and b2 indicate the alloy catalyst layer 10.
Shows the application range.

For this reason, the difference in the current density distribution in the entire sub-stack can be suppressed and the current density can be made more uniform, and the current does not concentrate on the oxidant gas inlet side to increase the temperature. Is reduced. Therefore, the maximum value of the concentration of the phosphoric acid vapor in the oxidizing gas decreases, and the amount of phosphoric acid taken out from the oxidizing gas outlet is reduced, so that the battery life is prolonged.

(4) Fourth Embodiment One embodiment corresponding to the invention described in claim 5 will be described below as a fourth embodiment with reference to FIG.
FIG. 6 is a partially transparent perspective view showing the configuration of the present embodiment.

(Configuration) First, the configuration of the present embodiment will be described. This embodiment relates to an apparatus for forming the platinum catalyst layer 9 and the alloy catalyst layer 10 on the surface of the electrode substrate 21 as described in the above embodiment. That is, in the present embodiment, the pyramid-shaped catalyst powder covering 1
At the apex of 9, a platinum catalyst pipe 17 for leading a platinum catalyst and an alloy catalyst pipe 18 for leading an alloy catalyst are connected separately on the left and right in the figure. Inside the catalyst powder cover 19,
Platinum catalyst and alloy catalyst piping 1 from platinum catalyst piping 17
Separating plate 20 for separating the alloy catalyst from No. 8 is fixed at a fixed angle with respect to the base of the quadrangular pyramid.
Further, an electrode substrate 21 for applying a catalyst is provided so as to be disposed below the catalyst powder cover 19, and a pressure reducing device 22 for sucking the catalyst powder is provided below the electrode substrate 21. .

(Operation and Effect) The operation and effect of the present embodiment as described above are as follows. That is, in the present embodiment, after setting the electrode substrate 21 and the decompression device 22 under the catalyst cover 19, the platinum catalyst powder is introduced from the platinum catalyst pipe 17 while the decompression device 22 is operated and sucked. Then, the alloy catalyst powder is introduced from the alloy catalyst pipe 18. Then, on the left electrode substrate 21 in FIG.
The platinum catalyst is uniformly applied, and the alloy catalyst is uniformly applied on the right side.

According to the present embodiment as described above, for example, a platinum catalyst layer and an alloy catalyst layer can be formed on a single electrode substrate 21 at one time.
The anode electrode 2 according to the third embodiment can be easily and efficiently manufactured. Therefore, it is possible to easily manufacture a fuel cell having the same effects as those of the first to third embodiments.

(5) Fifth Embodiment One embodiment corresponding to the invention described in claim 6 will be described below as a fifth embodiment with reference to FIG.
FIG. 7 is a partially transparent perspective view showing the configuration of the present embodiment.

(Configuration) First, the configuration of the present embodiment will be described. That is, the basic configuration of the present embodiment is the fourth configuration.
This is the same as the embodiment. However, in the fourth embodiment, the catalyst separation plate 20 is fixed at a fixed angle with respect to the base of the quadrangular pyramid, but in the present embodiment, the catalyst separation plate 20 is fixed. The angle with respect to the base can be freely changed. This angle is
It is configured to be variable from outside the catalyst powder cover 19 manually or by automatic control.

(Operation and Effect) The operation and effect of the present embodiment as described above are as follows. That is, the catalyst cover 19
After setting the electrode substrate 21 and the decompression device 22 in the lower part of
While sucking by the pressure reducing device 22, the platinum catalyst pipe 1
7, the platinum catalyst powder is charged, and the alloy catalyst powder is charged from the alloy catalyst pipe 18. Then, the platinum catalyst is uniformly applied on the left electrode substrate 21 in FIG. 7, and the alloy catalyst is uniformly applied on the right side. When manufacturing electrodes having different positions of the boundary between the platinum catalyst layer and the alloy catalyst layer, the same operation as described above is performed by changing the desired angle of the catalyst separation plate 20.

According to the present embodiment as described above, for example, a platinum catalyst layer and an alloy catalyst layer can be formed on a single electrode substrate 21 at one time. The same operation and effect as in the embodiment can be obtained. further,
Since an electrode having a different position at the boundary between the platinum catalyst layer and the alloy catalyst layer can be easily manufactured by one apparatus, the manufacturing efficiency can be further improved, and the manufacturing cost can be reduced.

(6) Sixth Embodiment One embodiment corresponding to the invention described in claim 7 will be described below as a sixth embodiment with reference to FIG.
FIG. 8 is a partially transparent perspective view showing the configuration of the present embodiment. That is, the basic configuration of the present embodiment is:
This is the same as the fourth embodiment. However, in the present embodiment, the length of the catalyst separation plate 20 does not reach the bottom of the quadrangular pyramid.

In this embodiment as described above, after the electrode substrate 21 and the pressure reducing device 22 are set below the catalyst cover 19, the platinum catalyst powder is removed from the platinum catalyst pipe 17 while being sucked by the pressure reducing device 22. The alloy catalyst powder is introduced from the alloy catalyst piping 18. Then, the platinum catalyst is uniformly applied on the left electrode substrate 21 in FIG. 8, and the alloy catalyst is evenly applied on the right electrode substrate. At this time, since the catalyst separation plate 20 does not reach the bottom of the quadrangular pyramid, the catalyst separation plate 20 does not contact the electrode substrate 21. Therefore, a groove is formed at the boundary between the platinum catalyst layer and the alloy catalyst layer,
It is possible to prevent the boundary portion of one catalyst layer from being thinner than the other catalyst layer.

According to the present embodiment as described above, for example, a platinum catalyst layer and an alloy catalyst layer can be formed on a single electrode substrate 21 at one time. The same operation and effect as in the embodiment can be obtained. further,
Preventing the formation of grooves at the boundary between the platinum catalyst layer and the alloy catalyst layer,
Since the thickness of the catalyst layer can be made uniform over the entire surface,
An electrode having more stable characteristics and excellent characteristics can be manufactured.

(7) Other Embodiments The present invention is not limited to the above embodiments. That is, as an embodiment corresponding to the invention of claim 4, it is also possible to use an alloy of platinum and palladium or an alloy of platinum and ruthenium as the alloy catalyst in the above embodiment. For example, an alloy catalyst of platinum and palladium is dispersed as fine particles together with a fluorine resin, kneaded, applied to an electrode substrate made of a porous material, heated and pressed to form a catalyst layer. Examination of the temperature characteristics of a small battery using the electrode manufactured in this way as an anode electrode shows that, when carbon monoxide is mixed in a fuel gas, as shown in FIG. The characteristics were remarkably improved as compared with the temperature characteristics.

Therefore, by using an alloy of platinum and palladium as the alloy catalyst in the above embodiment, in a fuel cell having a low-temperature region at the oxidant gas outlet, the characteristics of the oxidant gas outlet may be reduced. It can be greatly reduced. Thus, the difference in current density and the temperature difference in the plane direction of the battery are reduced, the concentration of phosphorus pentoxide diffused in the oxidizing gas is reduced, and the battery life can be extended. The same applies to the case where an alloy of platinum and ruthenium is used as an alloy catalyst.

As an embodiment corresponding to the eighth aspect of the present invention, in the anode electrode 2 in the first to third embodiments, the platinum catalyst layer 9 on the oxidant gas inlet side and the oxidant gas The two catalyst layers of the alloy catalyst layer 10 on the outlet side are each formed in a sheet shape, and they are arranged on an electrode substrate, and an electrolyte layer is stacked on the catalyst layer and pressed to form an electrode substrate. It is also possible to form a catalyst layer between the electrolyte and the electrolyte layer. According to such an embodiment, the catalyst layer can be reliably formed together with the pressure bonding of the electrolyte layer, so that the yield in forming the catalyst layer is improved.

Further, the sharing ratio between the platinum catalyst layer 9 and the alloy catalyst layer 10 in the anode electrode 2 does not need to be limited to the ratio described in the above embodiment, and may be another sharing method. The number of stacked cells can be freely increased or decreased at the design stage.

[0060]

According to the present invention as described above, by reducing the difference in the current density distribution, the vapor concentration of supersaturated phosphoric acid at the outlet of the oxidizing gas is reduced, and the reaction gas and the reaction gas are used together. It is possible to provide a phosphoric acid type fuel cell capable of reducing the amount of phosphoric acid taken out and extending the life of the battery, and a manufacturing apparatus and a manufacturing method for the electrode thereof.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a phosphoric acid type fuel cell according to the present invention.

FIG. 2 is an exploded perspective view showing a second embodiment of the phosphoric acid fuel cell of the present invention.

FIG. 3 is an exploded perspective view showing a third embodiment of the phosphoric acid fuel cell of the present invention.

FIG. 4 is an explanatory diagram showing in a graph the difference in battery voltage characteristics depending on the temperature between a battery using a platinum catalyst and a battery using an alloy catalyst.

FIG. 5 is an explanatory diagram showing in a graph the difference in battery voltage characteristics depending on the temperature between a battery using a platinum catalyst and a battery using an alloy catalyst.

FIG. 6 is a partially transparent perspective view showing a fourth embodiment of the apparatus for manufacturing an electrode for a phosphoric acid fuel cell of the present invention.

FIG. 7 is a partially transparent perspective view showing a fifth embodiment of the apparatus for producing an electrode for a phosphoric acid fuel cell of the present invention.

FIG. 8 is a partially transparent perspective view showing a sixth embodiment of the apparatus for producing an electrode for a phosphoric acid fuel cell of the present invention.

FIG. 9 is an exploded perspective view showing an example of a conventional phosphoric acid fuel cell.

FIG. 10 is a graph showing the relationship between the temperature and the vapor pressure of phosphorus pentoxide in a graph.

FIG. 11 is an explanatory diagram graphically showing a state change in the fuel cell along the oxidizing gas flow path.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrolyte layer 2 ... Anode electrode 3 ... Cathode electrode 4, 5 ... Electrolyte reservoir 6 ... Cooling plate 7 ... Cooling tube 8 ... Separator 9 ... Platinum catalyst layer 10 ... Alloy catalyst layer 11 ... Catalyst non-coating area 12-16 ... Single Battery 17: Pipe for platinum catalyst 18: Pipe for alloy catalyst 19: Cover with catalyst powder 20: Catalyst separator 21: Electrode substrate 22: Decompression device

Claims (8)

[Claims] 1. A plurality of single cells in which an electrolyte layer impregnated with phosphoric acid is sandwiched between a pair of an anode electrode and a cathode electrode, a catalyst layer is formed on the surfaces of the anode electrode and the cathode electrode, and a fuel cell is provided. An electrolyte reservoir formed with a groove for supplying an oxidizing gas is inserted at a position in contact with the anode electrode and the cathode electrode, respectively, in the electrolyte reservoir in contact with the anode electrode and the cathode electrode of a unit cell adjacent thereto. In a phosphoric acid fuel cell in which a gas-impermeable separator is inserted between the electrolyte reservoirs in contact with each other and a cooling plate is inserted for each of the plurality of cells, the oxidant gas outlet side is set to a low temperature region. A portion corresponding to an oxidizing gas outlet side of the catalyst layer of the anode electrode, wherein a cooling medium is provided in the cooling plate so as to be able to flow therethrough. , Phosphoric acid fuel cell, characterized by being formed by a platinum-based transition noble metal alloy catalyst. 2. The phosphoric acid fuel cell according to claim 1, wherein a region where no catalyst layer is formed is provided in a portion of the cathode electrode corresponding to the oxidant gas outlet. 3. The boundary between the platinum-based alloy catalyst layer formed on the oxidant gas outlet side formed on the anode electrode and the catalyst layer formed on the oxidant gas inlet side is smaller than the unit cell closer to the cooling plate. 3. The phosphoric acid type fuel cell according to claim 1, wherein a unit cell far from the cooling plate is provided at a position closer to the oxidant gas outlet. 4. The phosphoric acid fuel cell according to claim 1, wherein ruthenium or palladium is used as a transition noble metal that is a component of the alloy catalyst layer. 5. A phosphoric acid fuel cell electrode manufacturing apparatus for forming a catalyst layer by spraying a catalyst powder on an electrode substrate of a phosphoric acid fuel cell, wherein the quadrangular pyramid-shaped catalyst powder covering the electrode substrate is provided. At the apex portion, a platinum catalyst pipe for leading the platinum catalyst powder and an alloy catalyst pipe for leading the alloy catalyst powder are separately connected, and the inside of the catalyst powder cover is introduced from the platinum catalyst pipe. An apparatus for manufacturing an electrode for a phosphoric acid fuel cell, comprising: a separation plate for separating platinum catalyst powder and alloy catalyst powder introduced from the alloy catalyst pipe. 6. An angle of the separation plate with respect to a vertical direction is as follows:
6. The apparatus for manufacturing an electrode for a phosphoric acid fuel cell according to claim 5, further comprising a variable mechanism. 7. The apparatus for manufacturing an electrode for a phosphoric acid fuel cell according to claim 5, wherein a lower end of the separator is above a bottom surface of the catalyst powder cover. 8. A method for producing an electrode for a phosphoric acid type fuel cell, comprising forming a platinum-based transition noble metal alloy catalyst layer in a portion corresponding to an oxidant gas outlet of a catalyst layer of an anode electrode of a fuel cell. After forming the catalyst layer on the catalyst gas inlet side and the alloy catalyst layer on the oxidant gas outlet side in sheet form, respectively, the sheets of the two types of catalyst layers are arranged on the substrate of the anode electrode, respectively. A method for producing an electrode for a phosphoric acid fuel cell, comprising: forming a catalyst layer on the anode electrode by stacking and pressing an electrolyte layer on the catalyst layer sheet.