JPH08273696A - Fuel cell stack structure - Google Patents

Abstract

PURPOSE: To improve discharge efficiency of generating water, and effectively make a fuel cell compact in a solid high polymer type fuel cell. CONSTITUTION: When reaction gas is introduced to respective cells 4 to 7 of a fuel cell stack structure, oxygen and hydrogen react with each other in a catalytic electrode joined to both surfaces so as to sandwich a high polymer electrolyte film, and water is generated on the oxygen gas passage side. The generated water is discharged outside of a system through a main oxygen discharging passage by being accompanied by oxygen gas in a cathode electrode, that is, an oxygen gas passage. An electric current flows to the electrode by a hydrogen ion in the electrolyte film by electrochemical reaction, and electric power is generated. The electric power generated by the electrochemical reaction flows in the layering direction of an aggregate cell structure body 8 through a conductive separator. Since the respective cells 4 to 7 in the aggregate cell structure body 8 are insulated from each other, on a single cell, the electric current flows in the layering direction, and the electric power by the electrochemical reaction can be finally taken out of a pair of output terminals arranged on one end side of the fuel cell stack structure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art In general, a polymer electrolyte fuel cell is a power generating element composed of a hydrogen ion conductive solid polymer sandwiched between carbon electrodes carrying a platinum catalyst, that is, a solid polymer-electrode assembly and A gas passage groove for supplying a reaction gas is provided, and has a structure in which a gas separation member that supports the power generation element from both sides is laminated. Then, the fuel gas is supplied to one electrode, the oxidant gas is supplied to the other electrode, and the chemical energy related to the oxidation of the fuel gas is directly converted into the electric energy to extract the electric energy. There is. In a fuel cell, when electrochemistry occurs due to hydrogen and oxygen, a current is generated and water is generated on the cathode side. In the polymer electrolyte fuel cell, the operating temperature is lower than that of other fuel cells, so the water generated condenses, wets the wall surface of the gas passage and the electrode, and the generated water is successively generated on the wall surface and the electrode. Grows into water droplets, which grows and hinders the flow of gas and the diffusion of gas in the electrodes, so that the electrolytic reaction between the fuel gas and the oxidant gas is less likely to occur partially in the cell. The phenomenon that the output of the fuel cell is reduced occurs.

A conventional gas passage has a structure in which, for example, as shown in US Pat. No. 4,988,583, one gas passage connecting a gas supply port and a gas discharge port in a cell is flat. A gas separation plate is provided over the entire surface in contact with the electrode while meandering in view. Then, the generated water is entrained in the gas by the flow of the gas flowing through the passage and is discharged from the gas passage. Further, as disclosed in US Pat. No. 4,769,297, a porous plate is arranged on the back side of the electrode to discharge water generated at the cathode side electrode, and the water is generated through the porous plate. It is known to configure to drain water. A conventional fuel cell has a single cell composed of an electrolyte membrane as the power generating element as described above, catalyst electrodes arranged on both sides of the electrolyte membrane, and gas separation members provided on both sides of the catalyst electrode sandwiched between them. In the above configuration, a sufficient voltage and current that can be utilized for industrial purposes are not generated, so normally, by stacking this cell as one structural unit in multiple stages, desired voltage and current are secured. There is. However, when the laminated unit has a structure composed of a single cell, there is a problem that the fuel cell becomes large and the degree of freedom of the generated current or voltage is low.

From this point of view, for example, Japanese Patent Laid-Open No. 6-0
Japanese Patent No. 52881 discloses a fixed electrolyte fuel cell in which an assembled cell structure having a plurality of cells arranged in the same plane is laminated. If multiple cells are provided in the same plane, and if they are of the same size, the number of cells will increase, so the connection method will be set appropriately so that high-voltage high-current type or low-voltage high-current type There is an advantage that the form of the electric power that can be extracted can be appropriately controlled, such as a mold.

[0005]

[Problems to be Solved] However, the above-mentioned JP-A-6-05
The fuel cell disclosed in No. 2881 is a solid electrolyte type fuel cell that operates at a high temperature, and the operating conditions are different from those of the low temperature operation type polymer electrolyte fuel cell according to the present invention. Not applicable to any type of fuel cell. That is, in the fuel cell according to JP-A-6-052881, since the operating temperature is higher than the boiling point of water, the water generated on the surface of the electrolyte membrane becomes steam, and it is not necessary to consider the drainage structure thereof. On the other hand, in the low temperature operation type solid polymer electrolyte membrane fuel cell according to the present invention, the removal of the generated water generated by the electrochemical reaction, that is, the construction of the drainage structure is a serious problem. Further, in the configuration disclosed in the above publication, a ceramic or the like is used for the gas separation member so as to withstand a high temperature, and since this ceramic material is generally a poor conductor, the current generated by the reaction is collected. It is necessary to carry a special current collector on the gas separation member. On the other hand, in the polymer electrolyte fuel cell of the type targeted by the present invention, the gas separating member is basically different from the one using a conductive material such as a carbon material.

It is an object of the present invention to achieve good discharge efficiency of produced water in a polymer electrolyte fuel cell and to effectively achieve compactness.

[0007]

In order to achieve the above object, the present invention is configured as follows. That is, the polymer electrolyte fuel cell of the present invention, a power generating element composed of a polymer electrolyte membrane and electrode constituent members arranged on both sides of the polymer electrolyte membrane, and arranged along the power generating element, A gas separation member made of a conductive material that defines a gas flow passage for the reaction gas supplied to the power generation element between the power generation element and the gas separation member formed on both sides of the power generation element with respect to the power generation element. In a fuel cell in which a plurality of unit cells configured by being provided so that they can be supplied are arranged in the same plane, and a plurality of the power generation elements are arranged in the same plane in a fuel cell in which these are stacked, these power generation elements are insulated from each other. The power generating element assembly integrated through the insulating means and the insulating means that forms gas flow paths in a plurality of planar conductive members corresponding to the respective power generating elements and insulates them are integrated. gas A release member, wherein the planar conductive member on the power generating element of the power generating element assembly into contact to constitute a collective cell structure, characterized by being laminated thereto.

The insulating means includes a first insulating member integrated with the power generating element and a second insulating member integrated with the gas separating member, and the first and second insulating members. Cooperate with each other to form an insulating means, and a gas supply passage for supplying a reaction gas to the cells in each of the structures stacked through the first and second insulating members is provided. The first insulating member includes a gas seal member that blocks the gas flowing in the cell. In a preferred aspect, the gas separation member includes a recess for defining at least one continuous gas flow passage through which gas in the cell corresponds to one cell, and the gas flow passage has:
In the structure in which the plurality of cells are arranged in a plane,
At least one gas flow passage is formed in the plurality of cells through the separating member and the insulating means. The gas separating member is a partially conductive and partially insulating fiber composite member, and can be finished into a structure having a gas separating groove by a method such as press molding. That is, the gas passages can be simultaneously formed. For example, a composite member containing carbon particles or fibers is placed in the portion corresponding to the conductive portion, and only a non-conductive material containing no carbon particles is placed in the portion corresponding to the insulating portion and bonded to it. A gas separation member having a recess for a gas passage can be integrally formed by adding an agent and press-molding.

[0009]

The polymer electrolyte fuel cell of the present invention is constructed by stacking cells including a polymer electrolyte membrane, a power generating element having electrode constituent members on both sides, and a gas separating member arranged on both sides of the power generating element. However, for the structure that is a single-layer laminated unit,
Contains multiple cells. In the fuel cell having a stacked structure, that is, in the fuel cell having a stack structure, the reaction gas supply passage and the cooling water passage are provided along the stacking direction of the stack. That is, it is provided in a direction that penetrates each laminated structure. In each cell, the gas passage is formed so that the gas comes into contact with the electrode surface over a wide range as much as possible while meandering along the electrode surface and the electrochemical reaction effectively occurs. In this case, a plurality of cells are arranged in a plane in one aggregate cell structure, and normally, supply and discharge of the reaction gas and a cooling water passage are provided for each cell. In a preferred embodiment,
Common gas passage and cooling water passage,
The cooling water passage may be provided so as to circulate all the cells in the aggregate cell structure. In any case, oxygen gas and hydrogen gas used for the electrochemical reaction are evenly supplied to the surface of the electrolyte membrane from both sides of the polymer electrolyte membrane in opposite directions.

As described above, a feature of the present invention is that one cell structure is provided with a plurality of cells in a mutually insulated state on the same plane. In this case, the cells are constructed independently of each other with respect to the electricity generated by the electrochemical reaction. Therefore, in the fuel cell having the stack structure as described above, the main gas passage and the main cooling water passage are provided so as to penetrate each structure in the stacking direction, and the gas supply / exhaust passage and the cooling water passage to each structure are provided. Extend in a plane orthogonal to the main gas supply / discharge passage and the cooling water passage. Supply of electrolytic reaction gas and cooling water to each cell,
The discharge system can be provided independently or in common. In the case of providing them independently, by adopting a structure in which a plurality of cells are assembled in the present invention, a gas supply passage and a cooling water passage corresponding to each cell are required, but the layout of this main passage is integrated. Then, the entire structure can be made compact by providing each cell at the boundary that divides it. When each gas and cooling water passage is provided in common for a plurality of cells in one structure, one hydrogen supply port, one hydrogen discharge port, and one oxygen supply are provided for each structure. Mouth, one oxygen outlet, one cooling water inlet and one
Two cooling water outlets are provided. By thus providing the reaction gas and cooling water passages in common for a plurality of cells, each aggregate cell structure can be made smaller,
As a result, the entire stack structure can be made compact.

Further, in the fuel cell according to the present invention, since the gas separating member is conductive, the electric current generated by the electrochemical reaction in each cell comes into contact with the gas separating member via the ridges of the gas separating member. It flows into the cells of the aggregate cell structure. In this manner, the electric power collected in each cell sequentially flows in the stacking direction through the abutting cells and reaches the cells of the end structure. In a preferred embodiment, in the end aggregate cell structure, unlike the other intermediate aggregate cell structures, a pair of cells are arranged in a conductive state in the same plane. As a result, in the end structure, the current flows to other cells in the same plane, and then flows from the cells in the stacking direction through the abutting assembly again. As described above, in the structure according to the present invention, since each structure includes a plurality of cells, it is possible to establish a current path that extends in the stacking direction and reciprocates, so that it is possible to extract a high voltage. is there.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a perspective view of a fuel cell stack structure according to an embodiment of the present invention. The fuel cell 1 of this example is provided with a pair of output terminals 2 and 3 at one end for extracting electric power by an electrochemical reaction. As shown in FIG.
In the fuel cell 1 of this example, a predetermined number of assembly cell structures 8 in which four cells 4, 5, 6, 7 are arranged on the same plane are stacked, and a pair of current collector plates 9 and 10 are further provided at both ends thereof. End plates 1 that are insulators on both sides
1 and 12 are laminated. The collector plate 9 is formed by integrating the collector parts 2, 3, 9a and the insulating part 9b, and the collector plate 10 is formed by integrating the collector parts 10a, 10b and the insulating frame 10c. Are connected in series so that a high voltage can be taken out. One aggregate cell structure 8 is
As shown in FIG. 3, one power generation element 13 and this power generation element 1
3, a pair of gas separation members 14 and 15 from both sides, that is, separators 14 and 15 in which gas flow passages are formed, are attached to each other to form one aggregate cell structure 8 as shown in FIG.
Is configured.

In the configuration of this example, the fuel gas is hydrogen,
It is passed through to the anode electrode side. Further, the oxidant gas is air or oxygen, which is passed to the cathode electrode side. As shown in FIG. 5, one power generating element 13 has twelve openings for forming a main passage for reaction gas (hydrogen, oxygen) and cooling water at the boundary portion divided into a field shape. 16-
Solid polymer electrolyte membrane 28 provided with 27,
Catalytic electrode plates 29 to 32, which are conductors carrying four platinum particles, are arranged on both sides of the electrolyte membrane so as to correspond to the respective areas divided in the above-mentioned square shape, and a pair from the outside. The gaskets 33 and 34 are attached to the membrane electrode assembly having the polymer electrolyte membrane 28 in the middle and the catalyst electrodes on both sides thereof to form the power generating element 13 as shown in FIG. Referring to FIG. 7 and FIG.
In this example, as shown in FIGS. 3 and 4, the aggregate cell structure 8 is formed by combining separators 14 and 15 which are a pair of conductors on both sides of the power generating element. In this case, the conductor portions 14a and 15a are provided in the separators 14 and 15 corresponding to the cell regions divided into four in a square shape, and the conductor portions 14a and 15a are provided corresponding to the cell regions. 14a,
One meandering recess 35, that is, a groove for forming a gas flow passage is formed in 15a.

The catalyst electrode 29 of the power generating element 13 sandwiched between the pair of separators 14 and 15 is incorporated into one power generating element assembly in an integrated state with the gasket. In this case, the gaskets 33 and 34 are attached to the catalyst electrodes 29 to 32.
The insulation frame that divides into two works very well. Then, when the catalyst electrodes are assembled in the gaskets 33 and 34,
The surfaces of the insulating frames 33a and 34a of the gaskets 33 and 34 and the catalyst electrodes 29 to 32 are flush with each other.
Therefore, as shown in FIG. 4, the pair of separators 14, 15
Are pressed against each other with the power generating element sandwiched therebetween to form the aggregate cell structure 8, the structure 8 has a single plate shape.
Then, in the area of the catalyst electrode 29, the separators 14, 1
5 correspond to the conductor portions 14a and 15a, and the gasket 3
The insulating frame portions 14 of the separators 14 and 15 are included in the reference numerals 3 and 34.
Areas b and 15b correspond to the separators 14 and 15
And the power generation element 13 are watertightly and airtightly stacked to form the aggregate cell structure 8. As described above, in the conductive portions 14a and 15a of the separators 14 and 15, 35 grooves for defining gas flow passages with the catalyst electrode surfaces 29 to 32 meander on the catalyst electrode surfaces. Although provided, FIG. 9 conceptually shows the arrangement of the above-mentioned grooves from one surface of the plate-shaped aggregate cell structure. In FIG. 9, as described above, four cells 4 to 7 are used.
Is provided, and hydrogen is supplied from one hydrogen supply main passage 16 to the hydrogen passages 36a and 37a of the two cells 4 and 7, and the two hydrogen passages 36a and 37a are provided.
The outlets of a and 37a are 36b and 37b of the other two cells.
Together with this, it leads to the main hydrogen discharge passage 17 or 21. Also, for oxygen, one oxygen supply main passage 1
Oxygen is supplied to the oxygen passages 38a and 39a from the two cells 4 and 7, and the oxygen discharged from the two cells 4 and 7 is discharged together with the other two cells 38b and 39b. It is designed to be discharged to the passage 19 or 23. Thus two cells 4, 7 and 5,
6 are common to the supply and discharge systems of hydrogen and oxygen. Further, the cooling water is not shown in the figure, but similar commonization is achieved. In this case, as shown in the figure, the main passages 16 to 27 for hydrogen, oxygen, and cooling water are
It is provided in a boundary area that divides cells. As a result, the boundary region can be effectively used, and the stack structure can be made compact.

In the figure, the solid line indicates that the surface is provided on the front side, and the broken line indicates that the surface is provided on the back side. Therefore, taking hydrogen as an example, FIG.
As shown in FIG. 7, the cells 7 are commonly used so that one cell 7 is introduced from the front side and the other cell 4 is introduced from the back side. The supply and discharge of the cooling water has the same configuration, but it is provided for each stack of the two to three stages of the aggregate cell structure. That is, the conductive gas separating members 14 and 15 and the cooling water passage arranging member made of the same material are superposed at the stage of stacking several stages of the assembled cell structure so that the electrolysis region is cooled down uniformly in the same manner as the gas flow passage. Provide a cooling water passage. The gas separating members 14 and 15 of this example are electrically conductive,
It is made of a watertight and airtight material such as resin-impregnated carbon, CFRP, or amorphous carbon. Preferably, they are integrally formed by injection molding or molding. The recess 35 is provided as a portion corresponding to the gas flow passage formed in the separator conductor portions 14a and 15a.
However, in contrast to this, the surface of the ridge portion, that is, the convex portion 40, formed in close contact with the catalyst electrode surface,
It constitutes a current collector. This current collector is continuously connected via the power generating element.

In the above structure, when the reaction gas is introduced into the cells 4 to 7 of the fuel cell stack structure, oxygen reacts with hydrogen in the polymer electrolyte membrane to produce water in the hydrogen gas passage. The generated water is discharged to the outside of the system through the main oxygen discharge passage along with the oxygen gas in the cathode electrode, that is, the oxygen gas passage. Due to this electrochemical reaction, hydrogen ions flow in the electrolyte membrane, a current flows between the current collectors, and electric power is generated. Then, the electric power generated by the electrochemical reaction flows in the stacking direction of the aggregate cell structure 8 via the conductive separators 14 and 15. In this case, since the cells 4 to 7 in the aggregate cell structure 8 are insulated, the current flows in the stacking direction with respect to one cell, and then the conductive plates at the ends are adjacent to each other in the same plane. In the stacking direction, then flows in the stacking direction through each cell stacked on the cell, and further flows to another adjacent cell at the opposite end. With such a mechanism, electric power can be finally taken out from the pair of output terminals provided on one end side of the fuel cell stack structure. Referring to FIG. 10, there is shown another embodiment of the present invention. In the structure of this embodiment, a part of the insulating frames 14b and 15b around the separator is formed in an open state, and a conductive material is provided in that part. The portions are exposed to the outside of 14a and 15a. By doing in this way, it is possible to measure whether or not the reaction is properly occurring at any place.

Still referring to FIG. 11, there is shown a schematic view of the structure of an aggregate cell structure according to still another embodiment of the present invention. In the structure of this example, the mains of gas supply, discharge, cooling water supply, and discharge are further integrated, and are provided commonly to all four cells 4 to 7 arranged in one aggregate cell structure. (Only the front side is shown). That is, the hydrogen gas supply passage 16, the discharge passage 17, the oxygen gas supply passage 18, the discharge passage 19, the cooling water supply 24, the discharge passage 2
Only one 5 is provided for each. As a result, the area of the boundary portion of the assembled cell structure can be further reduced, and therefore the entire fuel cell stack structure can be made more compact. In the above example, an example in which four cells are assembled in the shape of a square in the aggregate cell structure has been described, but the invention is not limited to this, and a plurality of cells are assembled on the same plane and are insulated from each other. It can be widely applied to the arrayed configuration. In addition, each cell can achieve the object of the present invention if it is electrically insulated, and the supply and discharge systems of the reaction gas and the cooling water are not necessarily provided independently. Will be clear from.

[0018]

As described above, according to the present invention, in the solid polymer electrolyte membrane fuel cell, the generated water is smoothly discharged through the gas passage, and the conductive separator is disposed, It is possible to improve the efficiency of collecting the electric power generated by the electrochemical reaction without providing a special current collecting mechanism. Furthermore, in the present invention, since a plurality of cells are formed on the same plane, by easily performing a uniform electrochemical reaction, the reaction efficiency can be increased, and by appropriately selecting the connecting method, It is possible to increase the degree of freedom in extracting electric power such as high voltage type or high current type.

[Brief description of drawings]

FIG. 1 is a perspective view of a stack structure of a polymer electrolyte fuel cell according to an embodiment of the present invention,

2 is an exploded perspective view of the stack structure of the fuel cell of FIG.

FIG. 3 is an exploded perspective view of a collective cell structure,

FIG. 4 is a perspective view of a collective cell structure,

FIG. 5 is an exploded perspective view of a power generation element,

FIG. 6 is a perspective view of a power generation element.

7 is a cross-sectional view showing components of the aggregate cell structure in an exploded state at a position along line AA in FIG. 4;

FIG. 8 is a cross-sectional view of the aggregate cell structure,

FIG. 9 is a plan view of an aggregate cell structure,

FIG. 10 is a plan view of an aggregate cell structure according to another embodiment of the present invention,

FIG. 11 is a plan view of an aggregate cell structure according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell, 2, 3 output terminals, 4, 5, 6, 7 cells 8 assembly cell structure, 13 power generation element, 14, 15 gas separation member.

Claims (6)

[Claims] 1. A power generating element comprising a polymer electrolyte membrane and electrode constituent members arranged on both sides of the polymer electrolyte membrane, and a reaction arranged along the power generating element and supplied to the power generating element. A gas separating member made of a conductive material for defining a gas flow passage for the gas between the power generating element and each of the reaction gases provided on both sides of the power generating element so as to be able to supply to the power generating element. A plurality of unit cells configured are arranged in the same plane, and in a fuel cell in which the unit cells are stacked, a plurality of the power generation elements are arranged in the same plane, and one power generation element is insulated from one another through an insulating means. And a gas separation member that forms a gas flow path in a plurality of planar conductive members corresponding to the respective power generation elements and an insulating means that insulates the gas flow paths from each other. Aggregation 2. A fuel cell stack structure comprising a power generating element in contact with a planar conductive member to form an assembled cell structure, and the stacked cell structure is stacked. 2. The insulating means comprises a first insulating member integrated with the power generating element and a second insulating member integrated with the gas separating member, and the first and second insulating members are provided. A gas supply passage for supplying a reaction gas to the cells in each of the structures that are stacked by penetrating the first and second insulating members is provided while the members cooperate with each other to form an insulating unit. Is a fuel cell stack structure. 3. The fuel cell stack structure according to claim 2, wherein the first insulating member includes a gas seal member that shuts off a gas flowing through the cells. 4. The gas separating member is provided with a concave portion corresponding to one cell and defining a single continuous gas flow passage through which a gas circulating in the cell flows. The fuel cell stack structure according to claim 1. 5. The gas flow passage has a structure in which the plurality of cells are arranged in a plane, and a single gas flow passage is formed in the plurality of cells via the separating member and an insulating means. A fuel cell stack structure characterized by the above. 6. The fuel cell stack according to claim 6, wherein the gas separating member is a partially conductive and partially insulating fiber composite member and is finished by press molding into a structure having a gas flow passage. Construction.