JPH06283177A - Separator of fuel cell - Google Patents

Abstract

PURPOSE:To provide a separator of fuel cell, which can be manufactured at low cost, which is not deformed in the manufacturing process, and which improves the performance of the fuel cell by maintaining good connection with a unit cell. CONSTITUTION:A conventional pore is provided in the center part of an anode collecting plate 21. The peripheral part has a step difference of the same height as the thickness of an anode edge plate 23. The anode edge plate 23 is superimposed on the step difference part, and the anode edge plate 23 is sandwiched between the anode collecting plate 21 and a unit cell 1. A conventional pore is provided in the center part of the cathode collecting plate 22, and the peripheral part has a step difference of the same height as the thickness of the cathode edge plate 24. The cathode edge plate 24 is superimposed on the step difference part, and the cathode edge plate 24 is sandwiched between the cathode collecting plate 22 and the unit cell 1, in the process of assembling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell separator.

[0002]

2. Description of the Related Art As is well known, a fuel cell is a power generation device that directly converts an electrochemical reaction generated on an electrode into an electric output. To generate this electrochemical reaction, a fuel gas and an oxidant gas are used. Must be separately supplied to the fuel electrode and the air electrode facing each other with the electrolyte layer in between.

A functional component used for this purpose is a separator, and when a plurality of unit cells composed of a fuel electrode, an electrolyte layer and an air electrode are stacked to form a fuel cell stack, they are sandwiched between the unit cells. It has both the function of supplying the fuel electrode and the air electrode with the fuel gas and the oxidant gas separated from each other and the function of electrically connecting the adjacent single cells in series.

FIG. 5 shows an example of the structure of a fuel cell stack in which unit cells are stacked. In the figure, a unit cell 1 is composed of an electrolyte layer 2, a fuel electrode (hereinafter, referred to as an anode) 3 and an air electrode (hereinafter, referred to as a cathode) 4 that are arranged in close contact with each other on both surfaces of the electrolyte layer 2. It is configured based on a laminated body. The separator 5 is provided in contact with the unit cell 1 configured as described above, and the fuel cell main body is configured by alternately stacking them.

The separator 5 comprises an interconnector 6, an anode current collector plate 7 and a cathode current collector plate 8, an anode current collector support 9 and a cathode current collector support 10, and an anode edge plate 11 and a cathode edge plate 12, respectively. It has the following features:

That is, the interconnector 6 acts to isolate the flow of the fuel gas and the flow of the oxidant gas, and both the anode current collector plate 7 and the cathode current collector plate 8 supply the electric power generated in the unit cell 1 to the unit cell. 1 to uniformly guide the outside of the unit cell 1 and to support the entire surface of the unit cell 1 uniformly, and to provide a small-diameter hole (pore) for guiding the fuel gas or the oxidant gas to the anode 3 and the cathode 4. There is. In addition, the gas flow space has a corrugated anode current collector support 9 and cathode current collector support 10, and an end portion of which is an interconnector 6.
It is partitioned by an anode edge plate 11 and a cathode edge plate 12 which are formed so as to be closed by being integrated with.

Generally, as shown in the figure, the unit cells 1 and the separators 5 are alternately laminated, and a large number of these cells are collected to form a fuel cell laminate, which is practically used as a fuel cell that produces a large-capacity electric output. Be used for.

[0008]

As described above, the unit cell 1 contacts the anode current collector plate 7 and the anode edge plate 11 on one surface and the cathode current collector plate 8 and the cathode edge plate on the other surface. In contact with 12. Generally, one cell
In a fuel cell in which a predetermined number of separators and separators 5 are stacked, the fuel cell is operated while applying a constant surface pressure to the unit cell 1. Therefore, when the step difference between these contact surfaces becomes large, the unit surface is subjected to a locally applied force. Large stress is concentrated on the battery 1, which may cause cracking.

Further, when the contact between the anode 3 and the cathode 4 and the anode current collector 7 and the cathode current collector 8 cannot be maintained sufficiently due to the step difference in the contact surface, the electrical resistance increases, and this occurs. This causes a loss of electric power, which causes deterioration of the performance of the fuel cell.

Further, an anode 3 and a cathode 4,
If the contact between the anode edge plate 11 and the cathode edge plate 12 is insufficient, fuel gas or oxidant gas leaks to the outside of the separator.

Therefore, in order to eliminate the above-mentioned steps on the contact surface, a structure has been proposed in which the anode edge plate 11 and the anode current collector plate 7, and the cathode edge plate 12 and the cathode current collector plate 8 are integrally molded. There is. FIG. 6 shows this configuration.

That is, in the figure, 13 is an anode current collector plate in which the anode current collector plate 7 and the anode edge plate 11 are integrally molded, and 14 is the cathode current collector plate 8 and the cathode edge plate 12 are integrally formed. Reference numeral 15 denotes a molded cathode current collector plate, and 15 is a separator having the anode current collector plate 13 and the cathode current collector plate 14 integrally molded as described above. By using the separator 15 configured in this manner, the anode 3 and the cathode 4 can be brought into close contact with each other on the same plane, so that stress concentration caused by the above-described step difference can be avoided.

By the way, when manufacturing the anode current collector 13 and the cathode current collector 14 as described above, the anode 3
And it is necessary to process a large number of pores in the central portion for supplying the fuel gas and the oxidant gas to the cathode 4, respectively. This machining method includes machining, electrical discharge machining,
There is laser processing or etching processing.

However, in the case of machining,
Since the central portion where the pores are provided extends in the plane direction of the material, wrinkles occur at the boundary between the central portion and the peripheral portion where the pores are not provided. Also, when performing electrical discharge machining or laser machining,
Heat input causes strain and residual stress in the material. Furthermore, when etching is performed, no deformation or residual stress is generated, but various processes are required, which increases the manufacturing cost.

Therefore, an object of the present invention is to provide a fuel which can be manufactured at a low cost, which is not deformed during the manufacturing process, and which can maintain a good contact state with a unit cell and improve the performance of the fuel cell. It is to provide a battery separator.

[0016]

In order to achieve the above-mentioned object, the present invention is interposed between a stack of unit cells in which a fuel electrode and an air electrode are respectively adhered to both surfaces of an electrolyte layer, In the separator of the fuel cell in which the fuel gas and the oxidant gas are separately supplied to the air electrode in the separator of the fuel cell, the power generated in the single cell is adhered to the central portion of either the fuel electrode or the air electrode. And a peripheral edge portion of a pair of current collecting members that lead out to the outside are in contact with the peripheral edge portions of the fuel electrode and the air electrode and overlap with the edge member that forms the outer edge portion of the flow path. Is.

[0017]

[Function] Since the current collecting member and the edge member are separated from each other, the deformation and residual stress of the material in the manufacturing process are reduced,
Since the peripheral portion of the current collecting member is overlapped with the edge member, it is possible to eliminate the step generated at the abutting surface of the edge member and the current collecting member. As a result, the surface in contact with the unit cell is formed into a flat surface, and when the unit cell stack is assembled, local concentrated stress is prevented from occurring in the unit cell,
It is possible to prevent damage such as cracking, extend the life of the unit cell, and extend the life of the fuel cell stack. Further, the contact with the unit cell is improved, and the performance of the fuel cell can be improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cooling system according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a main part of an embodiment of the present invention. In the figure, reference numeral 20 denotes a separator. In this separator 20, the anode current collector plate 21 and the cathode current collector plate 22 have their respective peripheral edge portions formed by an anode edge plate 23 and a cathode edge plate 24.
Is configured to overlap. Other than that, the configuration is the same as that of the conventional separator 5 shown in FIG. 5 described above.

Therefore, the anode current collector plate 21 is provided with a small hole in the central portion as in the conventional case, and the peripheral edge portion is formed to have a step by the thickness of the anode edge plate 23. The anode edge plate 23 is overlaid on this step portion, and the anode current collector plate 21 and the unit cell 1
The fuel cell stack is assembled by sandwiching the anode edge plate 23.

As a result, the surface of the separator 20 that comes into close contact with the unit cell 1 forms a flat surface. here,
Since the height of the anode current collector support 9, the thickness of the anode current collector 21 and the height of the anode edge plate 23 have dimensional tolerances, the separator 20 was assembled depending on the combination of these dimensional tolerances. Sometimes anode current collector 21
There is a possibility that a gap may be formed between the step portion of the peripheral edge portion 21a and the anode edge plate 23. In this case, the surface of the separator 20 that comes into close contact with the unit cell 1 has a step, and the step may cause the unit cell 1 to be locally concentrated and cracked.

Therefore, in order to avoid this, in the manufacture of each component of the separator 20, the anode edge plate 23 and the step portion of the peripheral edge portion 21a of the anode current collector plate 21 are overlapped with each other without forming a gap. The height of the edge plate 23 is made slightly smaller. Due to the flexibility of the anode edge plate 23, the separator 20 is assembled so as to overlap the peripheral portion of the anode current collector plate 21.

The manufacturing and assembling of the cathode current collecting plate 22, the cathode edge plate 24 and the cathode current collecting plate support 10 are similar to those of the anode current collecting plate 21, the anode edge plate 23 and the anode current collecting plate support 9 described above. To have.

By carrying out the manufacturing and assembling as described above, the unit cell 1 is brought into close contact with the separator 20 having a flat surface without steps, so that local stress concentration occurs when assembled as a fuel cell stack. Never. Therefore, the life of the unit cell 1 is extended, and thereby the life of the fuel cell main body can be extended. Further, since the separator 20 has a small deformation amount, the separator 20 and the unit cell 1 are brought into close contact with each other in a good state, and the performance of the fuel cell main body is improved. further,
Since the separator 20 can be manufactured at low cost, the cost of the fuel cell can be reduced.

Next, a method of forming the anode current collector plate 21 and the anode edge plate 23, and the cathode current collector plate 22 and the cathode edge plate 24 by pressing will be described. A male and female mold is generally used for press molding, but here, a method of using male and female alone will be described.

FIG. 2 is an explanatory cross-sectional view showing a state in which an apparatus and materials for molding the anode current collector plate 21 and the anode edge plate 23, the cathode current collector plate 22 and the cathode edge plate 24 shown in FIG. 1 are set. Is. A female die 41 and an outer frame 42 surrounding the female die are set on the press head 40. Next, the edge plate material 43 and the current collector material 44 are placed in this order on the female die 41, and the rubber 45 having an arbitrary hardness is used as a medium for directly applying pressure to the current collector material 44. Put. Then,
Pressure is applied from above the rubber 45 with the press ram 46, and pressure is applied to the edge plate material 43 and the current collector material 44 via the rubber 45.

The edge plate material 43 is squeezed according to the shape engraved on the female die 41, and at the same time, the collector plate material 44 is the edge plate material.
It will be squeezed by the thickness of 43 and have a step. This is because the rubber 45 deforms following the shape of the female die 41. Here, the purpose of using the outer frame 42 is to contain the deformable rubber 45 in the outer frame 42 during pressure molding.
This is to prevent the protrusion from protruding into the outer frame 42 and consequently reduce the pressing force required for molding.

At the time of this molding, it is preferable to use, as the current collector plate material 44, one that has been previously provided with a large number of pores. Further, the edge plate material 43 and the collector plate material 44 may be simply temporarily joined in advance. For example, joining with an adhesive, spot welding, or the like.

By the above molding method, the anode edge plate 23, the anode current collector plate 21, and the cathode edge plate 24 shown in FIG.
The cathode current collector plate 22 is molded. According to such a method, the steps formed on the peripheral portions of the anode current collector plate 21 and the cathode current collector plate 22 are exactly the thicknesses of the anode edge plate 23 and the cathode edge plate 24, and the separator 20 becomes the unit cell 1. The surface in contact with is flat.

Needless to say, the same processing can be performed by using a male die instead of the female die 41 and by using a male and female die. Next, another embodiment of the present invention will be described with reference to FIG.

In the figure, reference numeral 30 denotes a separator. In the separator 30, the peripheral edges of the anode current collector plate 31 and the cathode current collector plate 32 are the anode edge plate 33 and the cathode edge plate, respectively.
Although it is configured to overlap with 34, this overlapping structure is different from the above-described embodiment.

That is, a step corresponding to the plate thickness of the anode current collector plate 31 is provided on the anode edge plate 33, and the anode current collector plate 31 is overlapped on this step part, and the anode edge plate 33 and the unit cell 1 are stacked.
The anode current collector plate 31 is sandwiched between and assembled.

As a result, the surface of the separator 30 that comes into close contact with the unit cell 1 forms a flat surface. here,
Since the height of the anode current collector support 9, the thickness of the anode current collector 31 and the height of the anode edge plate 33 have dimensional tolerances, the separator 30 was assembled depending on the combination of these dimensional tolerances. Sometimes anode current collector 31
There is a possibility that a gap will be created between the anode edge plate 33 and the step portion of the anode edge plate 33. In this case, the surface of the separator 30 that comes into close contact with the unit cell 1 has a step, and the step may cause the cell 1 to be locally concentrated and cracked.

Therefore, in order to avoid this, in the manufacture of each component of the separator 30, the anode edge plate 33 is so arranged that the anode current collector plate 31 and the stepped portion of the anode edge plate 33 overlap without any gap. Make the height slightly larger. Due to the flexibility of the anode edge plate 33, the separator 30 is assembled by stacking so that the anode edge plate 33 is pressed down at the peripheral edge of the anode current collector plate 31.

In manufacturing and assembling the cathode current collector 32, the cathode edge plate 34, and the cathode current collector support 10, the same relationship as that of the anode current collector 31, the anode edge plate 33, and the anode current collector support 9 described above is used. To have.

Next, a method of forming the anode current collector plate 31, the anode edge plate 33, the cathode current collector plate 32, and the cathode edge plate 34 by pressing will be described. FIG. 4 is a cross-sectional explanatory view showing a state in which an apparatus and materials for molding the anode current collector plate 31, the anode edge plate 33, the cathode current collector plate 32, and the cathode edge plate 34 shown in FIG. 3 are set. The reference numerals in the figure are the same as those in FIG. 2, and the method of setting each component is also the same as in the case of FIG. 2 described above. The difference from FIG. 2 is the positional relationship between the edge plate material 43 and the current collector material 44.
The current collecting plate material 44 is first placed in the recess of the female die 41, and then the current collecting plate material 43 is placed on the female die 41. Then, pressure is applied from above the rubber 45 by the press ram 46, and pressure is applied to the edge plate material 43 and the current collector material 44 via the rubber 45.

The edge plate material 43 is squeezed according to the shape engraved on the female die 41, and at the same time, it is deformed to have a step by the thickness of the current collector plate material 44. At the time of this molding, it is preferable to use, as the current collector material 44, one that has been previously provided with a large number of pores. Also, the edge plate material
The current collector plate material 43 and the current collector plate material 44 may be simply and temporarily preliminarily joined by an adhesive or spot welding. At this time, the edge plate material 43 is attached to the current collector material 44 and set in a state of floating in the air.

By the above molding method, the anode edge plate 33, the anode current collector plate 31, and the cathode edge plate 34 shown in FIG.
The cathode current collector plate 32 is molded. According to such a method, the steps of the anode edge plate 33 and the cathode edge plate 34 at the portions in contact with the anode current collector plate 31, the cathode current collector plate 32 are accurately determined by the steps of the anode current collector plate 31 and the cathode current collector plate 32. The thickness is equal to the thickness of the peripheral portion, and the surface of the separator 30 in contact with the unit cell 1 is flat.

It is needless to say that the same processing can be performed by using a male die instead of the female die 41 and by using a male and female die. By performing the manufacturing and assembling as described above, the unit cell 1 has the separator 30 having a flat surface without steps.
Therefore, when the fuel cell body is assembled as a laminated body, local stress concentration does not occur. Therefore, the life of the unit cell 1 is extended, and thereby the life of the fuel cell main body can be extended. Also, the separator 30
Since the amount of deformation is small, the separator 30 and the unit cell 1 are brought into close contact with each other in a good state, and the performance of the fuel cell main body is improved.
Furthermore, since the separator 30 can be manufactured at low cost, the cost of the fuel cell can be reduced.

Next, when the current collector plate and the edge plate are separately manufactured as described above, the central portion of the edge plate is hollowed out, and the current collector plate made of another material is fitted into the portion. Therefore, there is a waste of materials. In order to compensate for this drawback, there is also a configuration in which a large number of pores are processed in a material cut out from the central portion of the edge plate, molded as a current collector plate, and incorporated into a separator together with the edge plate. When a material is provided with a large number of pores by machining, the material is stretched in the plane direction, so that the formed current collector plate does not enter the hollowed hole of the edge plate and overlaps the edge plate at the end.
Alternatively, the material cut out from the central portion of the edge plate may be rolled and extended in the plane direction. As a result, the edge plate and the current collector plate can be manufactured without waste from a single material, and the cost can be reduced.

[0040]

As described above, according to the present invention, the fuel electrode is inserted between the stacks of the unit cells in which the fuel electrode and the air electrode are respectively adhered to both sides of the electrolyte layer,
In a fuel cell separator that has a flow path that separates and supplies the oxidant gas to the air electrode, adheres to the center of either the fuel electrode or the air electrode and guides the power generated by the unit cell to the outside. Since the peripheral portions of the pair of current collecting members that are in contact with each other are in contact with the peripheral portions of the fuel electrode and the air electrode and overlap with the edge member that forms the outer edge portion of the flow path, the life of the unit cell is extended. Therefore, the life of the fuel cell stack can be extended, and since the deformation amount is small, it can maintain good contact with the unit cell, improve the performance of the fuel cell, and provide a fuel cell separator that can be manufactured at low cost. .

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention.

FIG. 2 is an explanatory view showing a molding method according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a main part of another embodiment of the present invention.

FIG. 4 is an explanatory view showing a molding method of another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a main part of a conventional fuel cell separator.

FIG. 6 is a cross-sectional view showing a main part of a conventional fuel cell separator different from that shown in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single cell, 2 ... Electrolyte layer, 3 ... Anode, 4 ... Cathode, 5,15,20,30 ... Separator, 6 ... Interconnector, 7,13,21,31 ... Anode current collector, 8,14, 22, 32
… Cathode collector plate, 9… Anode collector support, 10…
Cathode current collector support, 11,23 ... Anode edge plate,
12, 24 ... Cathode edge plate, 40 ... Press head, 41 ... Female type, 42 ... Outer frame, 43 ... Edge plate material, 44 ... Current collecting plate material, 45
… Rubber, 46… press ram.

Claims (3)

[Claims] 1. A fuel cell and an oxidant gas are separated between the fuel electrode and the air electrode, respectively, which are inserted between a stack of unit cells in which a fuel electrode and an air electrode are closely attached to both surfaces of an electrolyte layer. In a separator of a fuel cell in which a flow path is formed to be supplied as a pair, a pair of current collecting members that come into close contact with the center of either one of the fuel electrode and the air electrode and lead out the electric power generated in the unit cell to the outside. The fuel cell separator is characterized in that the peripheral portion of the fuel cell contacts the peripheral portions of the fuel electrode and the air electrode and overlaps with the edge member forming the outer peripheral portion of the flow path. 2. The materials of the edge member and the current collecting member are overlapped and press-molded so that the surfaces of the edge member and the current collecting member in contact with the fuel electrode or the air electrode are formed into a single plane. The fuel cell separator according to claim 1, wherein the separator is a fuel cell separator. 3. The separator for a fuel cell according to claim 1, wherein the material cut off from the central portion of the edge member forms all or part of the current collecting member.