JP2002015751A - Fuel cell and its separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the accumulation of dimensional errors in the laminating direction even in the case many fuel cells and separators are piled in lamination and to improve the gas separation between the fuel gas region and the oxidizer gas region inside the fuel cell. SOLUTION: A separator which is composed by overlapping two sheets of plate shape separators 10, 20 is provided between the two top and bottom fuel cells 40. On each facing face of the two plate shape separators 10, 20, the passage forming grooves 15, 25 are formed at the position corresponding each other. As a result of the two passage forming grooves 15, 25 being combined, a gas passage of tunnel form is formed which links the gas manifold 51A and the gas chamber that is provided between the upper fuel cell 40 and the plate shape separator 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell formed by alternately stacking battery cells and separators, and more particularly to a gas passage structure formed by a separator in a fuel cell.

[0002]

2. Description of the Related Art In general, a fuel cell has a battery cell comprising a proton permeable membrane and a pair of electrode materials sandwiching the proton permeable membrane, and a gas chamber provided between one side of the battery cell and the electrode material. Are alternately laminated. One unit cell may be constituted by one battery cell and a separator arranged in parallel with the upper and lower layers thereof, and a stack of a plurality of unit cells may be understood as a fuel cell. In each unit battery, a battery cell interposed between the upper and lower separators corresponds to a kind of gas partition, and a fuel gas chamber (also referred to as a reducing agent gas chamber) is provided between one electrode material and the separator facing the same. An oxidizing gas chamber is defined between the other electrode member and the separator facing the other electrode member. Note that such a separator is also called a manifold plate because it serves to partition the gas chamber as described above. Further, in the fuel cell, respective gas flow paths (gas manifolds) for the fuel gas and the oxidizing gas are provided in the unit cell stacking direction. The fuel gas chamber of each unit cell is connected to a fuel gas gas manifold to receive the supply of the fuel gas. Similarly, the oxidizing gas chamber of each unit cell is connected to a gas manifold for the oxidizing gas to receive the oxidizing gas.

[0003] Japanese Utility Model Laid-Open No. 5-66875 discloses an example of a gas communication structure between a fuel gas gas manifold and a fuel gas chamber of each unit cell. According to this publication, a gas manifold (introduction hole and discharge hole) for fuel gas penetrates a peripheral portion of the manifold plate, and a fuel gas chamber is provided in a central region of one surface of the manifold plate. Deep recesses are provided. Further, a shallow concave portion (or a step portion) is provided between the deep concave portion in the center region and the peripheral portion having the gas manifold, and a bottom wall of the shallow concave portion is provided for connecting the deep concave portion and the gas manifold. A plurality of parallel grooves are formed. Then, at the time of assembling the fuel cell, a protection plate is fitted into the shallow recess to make each of the parallel grooves a tunnel-like passage.
Fuel gas flow between the gas manifold and the fuel gas chamber is ensured via these tunnel-like passages.

[0004]

The publication discloses that when a protective plate is fitted in the shallow recess, the surface of the plate and the surface of the manifold plate are flush with each other. However, when such a structure is actually adopted, it is difficult to make the surface of the protection plate flush with the surface of the manifold plate. This is because in today's era in which high-density stacking of unit batteries is required, the thickness of the manifold plate or the separator is inevitably reduced, and its thickness is reduced to about 1.0 mm or less.
Under such circumstances, if a protection plate and a shallow recess for accommodating the protection plate are to be designed, the thickness of the protection plate and the depth of the shallow recess need to be controlled with considerably high precision. Strict control of depth and depth is extremely difficult. For this reason, even if it is intended to increase the processing accuracy of the protection plate and the shallow recess, when the plate is actually fitted into the shallow recess, a part of the plate rises above the surface of the manifold plate, or the end face of the plate and the inside of the shallow recess are formed. It is difficult to avoid a gap between the wall and the wall.

[0005] Even if a part of the protection plate rises from the surface of the manifold plate to a level of several tens of microns, when a large number of unit batteries are stacked, slight dimensional deviations are accumulated and cannot be ignored. It will be large. This makes it impossible to maintain the parallel state between the plurality of unit cells, which not only hinders the assembly of the fuel cell, but also reduces the gas sealing performance. Also, when a gap is formed between the end face of the protection plate and the inner wall surface of the shallow recess, the gas sealing performance is similarly reduced. In particular, when the separation between the fuel gas region and the oxidizing gas region becomes insufficient inside the fuel cell and both gases are mixed with each other, the cell performance is significantly reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to keep a parallel state between unit cells as small as possible even when a large number of unit cells are stacked, so that a dimensional error is unlikely to accumulate in the stacking direction, and to provide a fuel gas region inside a fuel cell. An object of the present invention is to provide a fuel cell and a separator thereof having excellent gas isolation from an oxidizing gas region.

[0007]

According to a first aspect of the present invention, there is provided a battery cell comprising a proton-permeable membrane and a pair of electrode members sandwiching the proton-permeable membrane, and a battery cell disposed on one side of the battery cell. In a fuel cell, which is configured by alternately stacking separators that provide gas chambers therebetween, and is provided with a gas manifold that penetrates the stacked separator group in the stacking direction, the separators have substantially the same planar shape. The two plate-shaped separator pieces are configured to overlap each other, and at least one of the mating surfaces where the two plate-shaped separator pieces are in contact with each other, to form a gas passage connecting the gas manifold and the gas chamber. Is formed.

According to the present invention, the passage forming groove is provided on at least one of the mating surfaces of the two plate-shaped separator pieces, so that when the mating surfaces of the two plate-shaped separator pieces are brought into contact with each other, a separator is formed. The opening of the channel forming groove formed in one plate-shaped separator piece is closed by the mating surface of the other plate-shaped separator piece. As a result, the passage forming groove serves as a tunnel-shaped gas passage connecting the gas manifold and the gas chamber, and the gas flow between the gas manifold and the gas chamber is secured through the tunnel-shaped gas passage. According to this configuration, the two plate-shaped separator pieces do not have a relationship in which one is fitted to the other, but have an equivalent mating surface, and are in a relationship of merely joining them together. It is not so difficult to smooth each mating surface in advance in terms of processing technology. Therefore, even if a separator is composed of a plate-like separator piece having a mating surface having a high surface smoothness and a plurality of such separators are stacked, each unit battery The parallel state between them is not impaired, and dimensional errors are unlikely to accumulate in the stacking direction unlike the conventional example. Further, since the two plate-shaped separator pieces are not in a mutually engaged relationship, it is not necessary to form a fine step on both sides, and there is no cause for generating an unnecessary gap. Therefore, as far as the communication structure between the gas manifold and the gas chamber is concerned, a certain degree of hermeticity can be secured by itself.

According to a second aspect of the present invention, in the fuel cell according to the first aspect, a passage forming groove is formed on each of the mating surfaces of the two plate-shaped separator pieces at a position corresponding to each other, A gas passage connecting the gas manifold and the gas chamber is formed by combining these passage forming grooves. According to this configuration, since the passage-forming grooves formed on both of the two mating surfaces are combined to constitute one tunnel-like gas passage, the depth of one passage-forming groove is set to be relatively shallow. Also, a sufficient gas flow cross-sectional area can be given to the tunnel-shaped gas passage. Therefore, it is possible to reduce the thickness of each plate-shaped separator piece without lowering its mechanical strength, and it is possible to improve the stacking density of the fuel cell.

According to a third aspect of the present invention, in the fuel cell according to the first or second aspect, the plate-shaped separator piece having the passage-forming groove is formed so that the passage-forming groove communicates with the gas chamber. A communication hole penetrating the separator piece in the laminating direction is formed. According to the basic structure of the present fuel cell, the surface opposite to the mating surface of the plate-like separator pieces is the surface facing the electrode material of the battery cell, and the gas chamber is arranged on the opposite surface. In this regard, according to the configuration of claim 3, the communication hole provided through the separator piece in the stacking direction connects the passage configuration groove formed on the mating surface side with the gas chamber, so that the gas chamber is formed. Can communicate with the gas manifold via the communication hole and the passage forming groove.

According to a fourth aspect of the present invention, in the fuel cell according to the third aspect, a joining area between the two plate-like separator pieces is provided in a plane orthogonal to the laminating direction of the separators.
A gas sealing means is provided which surrounds a region where the gas manifold, the passage forming groove, and the communication hole are present. According to this configuration, when observed in a plane orthogonal to the laminating direction of the separators, the same kind of gas (for example, fuel gas) having the gas manifold, the passage forming groove (tunnel-like passage), and the communication hole communicating with each other exists.
Region is isolated from the region of a different gas (eg, an oxidizing gas) by being surrounded by the gas sealing means. For this reason, a situation in which two types of gases are mixed inside the fuel cell is reliably avoided, and a decrease in cell performance due to gas mixing can be prevented. The gas sealing means is made of rubber, O,
Preferably provided by vibration welding of a ring, adhesive or metallic material.

According to a fifth aspect of the present invention, in the fuel cell according to the fourth aspect, a sealing groove for accommodating the gas sealing means is formed on at least one of the mating surfaces of the two plate-shaped separator pieces. It is characterized by having. By providing the sealing groove on the mating surface of the plate-shaped separator pieces, the positioning of the gas sealing means provided in the joint region between the two plate-shaped separator pieces becomes easy. In addition, lateral displacement in the mating plane of the gas sealing means is effectively prevented. In addition, it is preferable to form the seal groove at a position corresponding to both of the mating surfaces of the two plate-shaped separator pieces.

According to a sixth aspect of the present invention, two plate-like separator pieces having substantially the same planar shape are overlapped with each other, and at least one of the mating surfaces where the two plate-like separator pieces contact each other is provided. A fuel cell separator, wherein a gas passage connecting groove for connecting a gas manifold and a gas chamber in the fuel cell is formed. The technical significance of the sixth aspect is substantially the same as that of the first aspect.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel cell according to this embodiment is obtained by stacking unit cells of two layers on a base separator piece 30 for providing a cooling medium flow path, as shown in FIGS. The minimum stacking group of the set is a plurality of the minimum stacking groups stacked vertically. Each of the unit batteries in the two layers is composed of a first separator piece 10, a second separator piece 20, and a battery cell 40 interposed between the separator pieces 10, 20. FIG. 1 shows a cross section taken along line AA in FIGS. 3, 5 and 7, and FIG.
Shows a cross section taken along the line BB in FIGS. As can be seen from these drawings, each separator piece 10, 2
A plurality of gas manifolds 51A, 51B, 52A, which penetrate the separator pieces in the laminating direction at the peripheral portions of 0, 30.
52B and cooling medium passages 53A, 53B are provided. A pair of gas manifolds 51A and 51B are manifolds for fuel gas as a reducing agent gas, and a pair of gas manifolds 52A and 52B are manifolds for air as an oxidizing gas. In general, a hydrogen gas or a reformed gas produced from methanol or natural gas is used as the fuel gas. In addition, cooling water as a cooling medium flows through the pair of cooling medium passages 53A and 53B.

A battery cell 40 constituting each unit battery includes a polymer solid electrolyte membrane (proton permeable membrane) 41 made of a polymer material having proton permeability and a negative electrode side provided thereunder. It is composed of an electrode member 42 and a positive electrode member 43 provided on the upper side. That is, the solid polymer electrolyte membrane 41 is sandwiched between the two electrode members 42 and 43. These electrode members 42 and 43 are made of a material having both excellent gas permeability and conductivity (for example, a porous carbon material). The electrode members 42 and 43 function as a gas diffusion layer and a gas distribution layer, and also function as electrodes involved in transfer and transfer of electrons in the electrochemical reaction. Each electrode material and the polymer solid electrolyte membrane 4
A catalyst layer (not shown) for promoting an electrochemical reaction is provided in a boundary region with the catalyst layer 1.

As shown in FIGS. 1 and 2, between the first separator piece 10 and the second separator piece 20, a space for disposing the sealing material 45 is secured so as to surround the battery cell 40. A spacer 44 is provided (only a partial cross section of the spacer 44 is shown in the figure). The spacer 44 is made of a rigid insulating material (for example, an insulating synthetic resin), and protects the battery cell 40 from mechanical pressure. That is, the solid electrolyte membrane 41 and the electrode 4
2 and 43 function as a shape-retaining material for preventing crushing. In the end region of the spacer 44, a gas manifold 51A for fuel gas (see FIG. 1) and a gas manifold 52A for air (see FIG. 2) are formed in a vertical direction (stacking direction). The sealing material 45 provided in the vicinity of the spacer 44 is provided between each gas manifold and the battery cell 40.
Cuts off communication with

In the unit cells of each level, the battery cells 40
The first separator piece 10 located on the upper side of FIG. 3 has a planar rectangular shape as shown in FIGS. 3 and 4. FIG. 3 shows the entire upper surface of the first separator piece 10, and FIG. 4 shows a part of the lower surface thereof. The first separator piece 10 is a member for separating the battery cell 40 from the battery cell 40 on the upper floor, and a gas for forming a gas chamber for air between the battery cell 40 and the electrode material 43 of the battery cell 40. It is also a chamber component.

At one corner of the first separator piece 10, the gas manifolds 51A and 52A and the cooling medium passage 53 are provided.
A is formed to penetrate, and the gas manifolds 51B, 52B and the cooling medium passage 53B are formed to penetrate at corners at diagonal positions of one corner. As shown in FIG.
A series of recesses 11 (also referred to as groove patterns) including a plurality of grooves are formed in the central region of the lower surface of the first separator piece 10 which is the surface facing the electrode material 43.
As indicated by the broken line in FIG. 3, the series of recesses 11 meanders in an S-shape, and both end regions reach the vicinity of the gas manifold groups located at both diagonal positions of the separator pieces. As shown in FIGS. 1 and 2, when the lower surface of the first separator piece 10 is superimposed on the upper surface of the battery cell 40, the concave portion 11 forms a flow path adjacent to the electrode material 43 and meandering in an S shape. Provide a gas chamber with Then, both end regions of the flow path of the gas chamber communicate with the air gas manifolds 52A and 52B.

As shown in FIGS. 3 and 4, the first gaskets 52A and 52
In the vicinity of each of 2B, a plurality of communication holes 12 (four per gas manifold in this example) are formed penetrating the separator piece in the thickness direction (that is, the laminating direction). In addition, on the upper surface of the first separator piece 10, a passage forming groove 13 that connects the communication hole 12 and the corresponding gas manifold 52A or 52B is formed for each communication hole 12. In addition, the upper surface of the first separator piece 10
It is a mating surface that comes into contact with the lower surface of the second separator piece 20 (or the lower surface of the base separator piece 30) of the unit battery in the upper layer. As shown in FIG. 2, a passage forming groove 23 is formed on the lower surface of the second separator piece 20 corresponding to the communication hole 12 and the passage forming groove 13 formed in the first separator piece 10. One end of the passage forming groove 23 reaches the air gas manifold 52A or 52B (see FIGS. 2 and 6). The pair of upper and lower passage forming grooves 13 and 23 are combined to form a horizontal tunnel-like gas passage, and the horizontal gas passage connects the communication hole 12 with the air gas manifold. That is, each of the pair of air gas manifolds 52 </ b> A and 52 </ b> B is connected to the end region of the gas chamber 11 via the corresponding passage forming grooves 13 and 23 and the communication hole 12.

Further, as shown in FIGS. 1 to 4, the upper surface of the first separator piece 10 is a surface orthogonal to the laminating direction of the separator pieces and a mating surface for joining to the lower surface of the second separator piece 20. Has become. A series of seal grooves 14 are formed on the mating surface at the boundary position between the central region and the peripheral region, and the seal grooves 14 divide the upper surface of the separator piece into six convenient regions. That is, the central area on the back side of the gas chamber concave portion 11 and the cooling medium passages 53A, 53
3B is a peripheral area, two fuel gas areas, and two oxidant gas areas. Each of the fuel gas regions includes a fuel gas gas manifold 51A or 51B and three passage forming grooves 15, and a seal groove 14 is provided so as to surround them. Each of the oxidizing gas regions includes an air gas manifold 52A or 52B, four communication holes 12, and four passage forming grooves 13, and a seal groove 14 is provided so as to surround them. ing.
As shown in FIGS. 1 and 2, in the series of seal grooves 14, a seal member 54 as gas sealing means corresponding to the shape of the seal grooves is provided. The sealing material 54 separates the six regions from each other in a joining region between the first separator piece 10 and the second separator piece 20, and blocks fluid communication between the regions. In a region shown in black in FIG. 4 (the lower surface of the first separator piece 10), a sealing material 45 provided near the spacer 44 is disposed. The position of the seal material 45 substantially coincides with the position of the seal groove 14 on the upper surface except for a part.

In the unit cells of each layer, the battery cells 40
As shown in FIGS. 5 and 6, the second separator piece 20 located on the lower side has the same planar rectangular shape as the first separator piece 10. FIG. 5 shows the entire upper surface side of the first separator piece 10, and FIG. 6 shows a part of the lower surface side. This second
The separator piece 20 is a member that separates the battery cell 40 from the battery cell 40 on the lower floor.
It is also a gas chamber constituting member for forming a gas chamber for fuel gas between the electrode member 42 and the electrode member 42.

At one corner of the second separator piece 20, the gas manifolds 51A and 52A and the cooling medium passage 53 are provided.
A is formed to penetrate, and the gas manifolds 51B, 52B and the cooling medium passage 53B are formed to penetrate at corners at diagonal positions of one corner. As shown in FIG.
On the upper surface of the second separator piece 20, which is the surface facing the electrode material 42, a series of concave portions 21 (also referred to as groove patterns) including a plurality of grooves are formed in the central region.
The series of concave portions 21 meander in an S-shape, and both end regions reach the vicinity of the gas manifold group located at both diagonal positions of the separator pieces. As shown in FIGS. 1 and 2, when the upper surface of the second separator piece 20 is superimposed on the lower surface of the battery cell 40, the recess 21 forms a flow path adjacent to the electrode material 42 and meandering in an S shape. Provide a gas chamber with Then, both end regions of the flow passage of the gas chamber communicate with the fuel gas gas manifolds 51A and 51B.

As shown in FIGS. 5 and 6, a plurality of communication holes 22 (in this example, 3 per gas manifold) are provided in the second separator piece 20 near each of the fuel gas gas manifolds 51A and 51B. Are formed penetrating the separator piece in the thickness direction (that is, the laminating direction). In addition, on the lower surface of the second separator piece 20, for each communication hole 22, a passage forming groove 25 that connects the communication hole 22 and the corresponding gas manifold 51A or 51B is formed. Also, the lower surface of the second separator piece 20 is a mating surface that comes into contact with the upper surface of the first separator piece 10 (or the upper surface of the base separator piece 30) of the unit battery in the lower layer. As shown in FIG. 1, a passage forming groove 15 is formed on the upper surface of the first separator piece 10 corresponding to the communication hole 22 and the passage forming groove 25 formed in the second separator piece 20. One end of the passage forming groove 15 reaches the fuel gas gas manifold 51A or 51B (see FIGS. 1 and 3). The pair of upper and lower passage forming grooves 25 and 15 are combined to form a horizontal tunnel-shaped gas passage, and this horizontal gas passage communicates the communication hole 22 with the fuel gas gas manifold. That is, each of the pair of fuel gas gas manifolds 51A and 51B is connected to the end region of the gas chamber 21 via the corresponding passage forming grooves 25 and 15 and the communication hole 22.

Further, as shown in FIGS. 1, 2, 5 and 6, the lower surface of the second separator piece 20 is a surface orthogonal to the laminating direction of the separator pieces and is used for bonding to the upper surface of the first separator piece 10. It is a mating surface. A series of seal grooves 24 are formed on the mating surface at a boundary position between the central region and the peripheral region. This seal groove 24
Is provided at a position corresponding to the seal groove 14 on the upper surface of the first separator piece, and similarly to the seal groove 14, partitions the lower surface of the second separator piece into six regions. That is, the central region on the back side of the gas chamber concave portion 21 and the cooling medium passages 53A, 53
3B is a peripheral area, two fuel gas areas, and two oxidant gas areas. Each of the fuel gas regions includes a fuel gas gas manifold 51A or 51B, three communication holes 22 and three passage forming grooves 25, and a seal groove 24 is provided so as to surround them. . In addition, each of the oxidant gas areas has a gas manifold 52 for air.
A or 521B and the four passage forming grooves 23 are included,
The seal groove 24 is provided so as to surround them. As shown in FIG. 1 and FIG.
A seal member 54 as a gas seal means corresponding to the shape of the seal groove is provided in the seal member 4. FIG. 5 (second
A sealing material 45 provided in the vicinity of the spacer 44 is disposed in a region indicated by black paint on the upper surface of the separator piece 20). The position of the sealing material 45 is determined by the position of the sealing groove 24 on the lower surface side.
It is almost the same except for the position and part.

The basic separator piece 30 to be interposed between the unit cells when assembling the fuel cell has the same planar square shape as the first and second separator pieces 10 and 20, as shown in FIGS. Make FIG. 7 shows a basic separator piece 30.
8 shows a part of the lower surface side. This base separator piece 30 is composed of two battery cells 40.
And a member for forming a flow chamber for cooling water as a cooling medium between the two unit batteries.

At one corner of the base separator piece 30, the gas manifolds 51A and 52A and the cooling medium passage 53 are provided.
A is formed to penetrate, and the gas manifolds 51B, 52B and the cooling medium passage 53B are formed to penetrate at corners at diagonal positions of one corner. As shown in FIG.
A series of recesses 31 (also referred to as groove patterns) including a plurality of grooves are formed in the lower surface of the base separator piece 30 which is the mating surface with the upper surface of the first separator piece 10 in the central region. As indicated by the broken line in FIG. 7, the series of concave portions 31 meander in an S-shape, and both end regions thereof reach the vicinity of the cooling medium passages 53A and 53B located at both diagonal positions of the separator pieces. The two end regions of the series of recesses 31 and the cooling medium passages 53A and 53B communicate with each other through a pair of communication grooves 32 formed on the lower surface of the base separator piece 30. The lower surface of the base separator piece 30 is the first separator piece 1
When superposed on the upper surface of the cooling water flow path 0, the recess 31 and the communication groove 32 connect the two cooling medium passages 53A and 53B and constitute a cooling water flow chamber having a flow path meandering in an S shape.

Further, as shown in FIGS. 1, 2, 7 and 8, the upper surface of the base separator piece 30 is a surface orthogonal to the laminating direction of the separator pieces and is joined to the lower surface of the second separator piece 20. Surface. In this mating surface, a seal groove 33 is formed which matches the seal groove 24 on the lower surface of the second separator piece. As shown in FIGS. 1 and 2, a sealing material 54 as gas sealing means is provided in a tunnel formed by the two sealing grooves 24 and 33. On the other hand, the lower surface of the base separator piece 30 is a surface orthogonal to the laminating direction of the separator pieces and a mating surface for joining to the upper surface of the first separator piece 10.
In this mating surface, a seal groove 34 substantially coinciding with the seal groove 14 on the upper surface of the first separator piece 10 except for a part thereof is formed. As suggested in FIGS. 1 and 2, a sealing material 54 as a gas sealing means is provided in a tunnel formed by the two sealing grooves 14 and 34. The sealing members 54 disposed above and below the base separator piece 30 are the first
And the same function as the sealing material 54 disposed in the boundary region between the second separator pieces 10 and 20.

The upper surface of the base separator piece 30 is involved in forming a gas passage connecting the gas chamber 21 provided by the second separator piece 20 and the fuel gas gas manifold 51A or 51B. That is, as shown in FIG. 1, the lower opening of the passage forming groove 25 formed on the lower surface of the second separator piece 20 is closed by the upper surface of the basic separator piece 30, so that the horizontal hole connecting the communication hole 22 and the gas manifold is formed. A simple tunnel-like gas passage is formed. Similarly, the base separator piece 3
0 is the gas chamber 1 provided by the first separator piece 10.
1 and the formation of a gas passage connecting the air gas manifold 52A or 52B. That is, although not directly shown in FIG. 2, as can be understood therefrom, by closing the upper opening of the passage forming groove 13 formed on the upper surface of the first separator piece 10 by the lower surface of the base separator piece 30,
A horizontal tunnel-like gas passage connecting the communication hole 12 and the gas manifold is formed.

As can be seen from the above description and FIGS. 1 and 2, two first separator pieces 10, two second separator pieces 20, one basic separator piece 30 and two battery cells 40 are fixed. By laminating according to the order of
One minimum stacking group composed of two levels of unit cells and one level of cooling medium layer is configured. In a fuel cell in which a plurality of such minimum stacking groups are stacked, unit cells in two layers and cooling medium layers in one layer are alternately arranged. As a result, there are two types of structures in the separator as a partition wall interposed between the two battery cells 40. One is a two-layer structure separator having a thickness t by laminating a second separator piece 20 on a first separator piece 10 as shown in FIGS. 1 and 2. The other is a three-layer structure separator constituted by sandwiching a base separator piece 30 between a first separator piece 10 and a second separator piece 20, as can be inferred from FIGS. The thickness t of the two-layer structure separator is preferably set to 0.5 mm to 1.5 mm (t = 1.0 mm in this example), but may be other values depending on the groove depth. Three separator pieces 10, 2
The thickness of each of 0 and 30 is set to about half of t. Therefore, the depths of the concave portions 11 and 12 and the passage forming grooves 13, 15, 23 and 25 constituting each gas chamber are very shallow. As described above, the extremely shallow concave portions 11 and 12 and the passage forming grooves 13, 15, 23 and 25 can be processed by various methods. However, in order to avoid the local distortion and secure the processing accuracy of the concave portions and the grooves. Preferably employs an electrolytic etching method. Note that stainless steel, aluminum-based metal, titanium-based metal, or carbon-based material can be used as a constituent material of the separator pieces 10, 20, and 30. Further, the surface of the separator piece after processing the recesses and grooves is plated as necessary.

In such a fuel cell, the fuel gas supplied via one of the fuel gas gas manifolds 51A is supplied to the passage forming groove 25 (and 15) and the communication hole 22.
Flows into the gas chamber 21 on the negative electrode side, and flows out therefrom through the communication hole 22 and the passage forming groove 25 (and 15) to the other fuel gas gas manifold 51B (see FIG. 1). Similarly, the air provided via one air gas manifold 52A is supplied to the passage forming groove 13 (and 2).
3) and flows into the gas chamber 11 on the positive electrode side through the communication hole 12, and flows out therefrom to the other air gas manifold 52B through the communication hole 12 and the passage forming groove 13 (and 23) (see FIG. 2). ). In each of the battery cells 40, power generation is performed based on a known electrochemical reaction using fuel gas and air supplied from the upper and lower gas chambers.

(Effects) According to the present embodiment, the following effects can be obtained. According to this fuel cell, each plate-like separator piece 10, 20, which is a constituent element of the two-layer structure or the three-layer structure separator,
Reference numerals 30 each have a smooth and equivalent mating surface, and a separator is formed by surface-bonding them. Therefore, the parallel state between the layers is hardly damaged, and unlike the conventional example that partially adopts the step structure,
No dimensional errors are accumulated in the stacking direction. This contributes to improving the gas sealing performance of the fuel cell by itself, apart from the viewpoint of the quality of the gas sealing means.

With respect to the tunnel-shaped gas passage set in the boundary region between the first separator piece 10 and the second separator piece 20, the passage forming grooves (15, 25) formed on both the respective mating surfaces and (13, 23) are combined to form one tunnel-like gas passage. For this reason, even if the depth of each passage forming groove is relatively shallow, a sufficient gas flow cross-sectional area is provided to the tunnel-shaped gas passage.
This makes it possible to reduce the thickness of each separator piece as much as possible without lowering the mechanical strength, thereby increasing the stacking density of the fuel cell and contributing to improved cell performance.

The fuel gas region defined by the gas manifolds 51A and 51B, the passage forming grooves 15 and 25, and the communication hole 22 is surrounded by the sealing material 54 housed in the sealing grooves 14 and 24 to form another region. Is reliably isolated from Similarly, the oxidizing gas region formed by the gas manifolds 52A and 52B, the passage forming grooves 13 and 23, and the communication hole 12 is also surrounded by the sealing material 54 accommodated in the sealing grooves 14 and 24 to form another region. Is reliably isolated from Therefore, a situation in which the two types of gases are mixed with each other inside the fuel cell is reliably avoided, and a decrease in cell performance is prevented.

According to this fuel cell, not only the gas isolation between the fuel gas region and the oxidizing gas region inside the cell is enhanced, but also gas leakage to the outside can be effectively prevented. The graph of FIG. 9 shows the result of measuring the change over time of the internal pressure when a required gas is sealed in a fuel cell in which 100 battery cells are stacked and the entrance and exit of each gas manifold are closed. The internal pressure is measured using a pressure gauge, and the gauge pressure (internal pressure) indicates a relative pressure based on the atmospheric pressure. In the fuel cell of this embodiment, the gauge pressure after 24 hours was almost equal to the initial gauge pressure (0.2 MPa = about 2 atm), and almost no gas leakage was observed. On the other hand, in the fuel cell employing the same structure as the conventional example, the gauge pressure after 24 hours is changed to the initial gauge pressure (0.
(2 MPa = about 2 atm), a decrease of 10% or more thereof, and slight gas leakage was observed. This comparative experiment also proves that the fuel cell of the present invention has better airtightness or gas sealability than the conventional example.

(Modification) The above embodiment may be modified as follows. As the seal members 45 and 54, any of rubber, metal O-ring, and adhesive can be used. In particular, when a resin material is used, a fluorine or silicone resin having excellent corrosion resistance is preferable.
On the other hand, instead of such a general sealing material, gas sealing means formed by vibration welding a metal material may be employed.

On the upper surface of the base separator piece 30 joined to the lower face of the second separator piece 20 shown in FIG. 1, a passage forming groove corresponding to the passage forming groove 25 on the second separator piece 20 side is formed. A tunnel-like passage having a sufficient gas flow cross-sectional area in the boundary region between 20, 30 may be formed. Further, as suggested from FIG. 2, a passage forming groove corresponding to the passage forming groove 13 on the first separator piece 10 side is formed on the lower surface of the base separator piece 30 joined to the upper surface of the first separator piece 10, A tunnel-like passage having a sufficient gas flow cross-sectional area in the boundary region between the separator pieces 10 and 30 may be formed.

[0037]

As described above in detail, according to the present invention, even when a large number of unit batteries are stacked, a dimensional error hardly accumulates in the stacking direction, and the parallel state between the unit batteries can be maintained as much as possible. Further, the gas isolation between the fuel gas region and the oxidizing gas region inside the fuel cell can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a part of a stacked structure of a fuel cell.

FIG. 2 is a cross-sectional view showing a part of a stacked structure of a fuel cell.

FIG. 3 is a plan view showing the entire upper surface side of a first separator piece.

FIG. 4 is a bottom view showing a part of the lower surface side of the first separator piece.

FIG. 5 is a plan view showing the entire upper surface side of a second separator piece.

FIG. 6 is a bottom view showing a part of a lower surface side of a second separator piece.

FIG. 7 is a plan view showing the entire upper surface of the base separator piece.

FIG. 8 is a bottom view showing a part of the lower surface of the base separator piece.

FIG. 9 is a graph showing a measurement result of a temporal change in gas pressure in a comparative experiment.

[Explanation of symbols]

10, 20, 30: plate-shaped separator piece, 11, 21, recess (gas chamber), 12, 22, communication hole, 13, 15, 2
3, 25: passage forming groove, 14, 24, 33, 34: sealing groove, 40: battery cell, 41: polymer solid electrolyte membrane (proton permeable membrane), 42, 43: electrode material, 51A, 51
B, 52A, 52B: gas manifold; 54: sealing material (gas sealing means).

Claims (6)

[Claims] 1. A battery cell comprising a proton permeable membrane and a pair of electrode materials sandwiching the proton permeable membrane, and a separator provided on one side of the battery cell and providing a gas chamber between the battery material and the electrode material. In a fuel cell provided with a gas manifold penetrating the stacked separator group in the stacking direction while being stacked, the separator is configured by stacking two plate-shaped separator pieces having substantially the same planar shape. In addition, at least one of the mating surfaces where the two plate-shaped separator pieces are in contact with each other, a passage forming groove for forming a gas passage connecting the gas manifold and the gas chamber is formed. Features fuel cell. 2. A gas passage forming groove is formed at a position corresponding to each other on both mating surfaces of the two plate-shaped separator pieces, and the gas manifold and the gas chamber are formed by combining the gas passage constituting grooves. The fuel cell according to claim 1, wherein a gas passage connecting the fuel cell and the fuel cell is formed. 3. A communication hole penetrating the separator piece in the laminating direction so as to communicate the gas passage with the gas chamber, in the plate-like separator piece having the passage forming groove formed therein. The fuel cell according to claim 1, wherein: 4. A gas seal surrounding a region where the gas manifold, the passage forming groove and the communication hole are present in a plane orthogonal to the laminating direction of the separator, in a joining region of the two plate-like separator pieces. 4. The fuel cell according to claim 3, further comprising means. 5. A sealing groove for accommodating said gas sealing means is formed in at least one of the mating surfaces of said two plate-shaped separator pieces.
A fuel cell according to claim 1. 6. A fuel cell according to claim 1, wherein two plate-like separator pieces having substantially the same planar shape are overlapped with each other, and at least one of the mating surfaces where said two plate-like separator pieces come into contact with each other is provided with a gas in a fuel cell. A fuel cell separator, wherein a passage forming groove for forming a gas passage connecting the manifold and the gas chamber is formed.