JP2000311696A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce the dimension in the height direction and provide desired power generation performance with a simple structure. SOLUTION: A first separator 14 is so structured that its surface 14a is formed into a rectangular shape, a fuel gas passage 42 communicating with a fuel gas inlet 36a and a fuel gas outlet 38b is formed in the surface 14a, and the fuel gas passage 42 extends along the long side direction and is formed into a meander shape folded back on the sides of the short sides 35b to run the fuel gas in the gravity direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell stack in which a plurality of unit fuel cells each having an electrolyte sandwiched between an anode and a cathode are stacked with a separator interposed therebetween.

[0002]

2. Description of the Related Art For example, a solid polymer fuel cell is a unit fuel comprising an electrolyte comprising a polymer ion exchange membrane (cation exchange membrane) and an anode electrode and a cathode electrode provided on both sides of an electrolyte. It is constituted by sandwiching the battery cells by the separator. Usually, a predetermined number of unit fuel cells and separators are stacked to be used as a fuel cell stack.

In this type of fuel cell, a fuel gas, for example, hydrogen gas, supplied to an anode electrode is hydrogen-ionized on a catalyst electrode and moves to a cathode electrode via a moderately humidified electrolyte. I do. The electrons generated during that time are taken out to an external circuit and used as DC electric energy. Since an oxidant gas, for example, oxygen gas or air is supplied to the cathode side electrode, the hydrogen ions, the electrons, and the oxygen gas react with each other to generate water at the cathode side electrode.

In order to supply a fuel gas and an oxidizing gas to the anode electrode and the cathode electrode, respectively, a conductive porous layer such as a porous carbon paper is usually provided on the catalyst electrode layer (electrode surface). Are sandwiched by the separators, and one or a plurality of gas passages having a uniform width are provided on the surfaces of the separators facing each other.

[0005] In this case, condensed water or water produced by the reaction may exist in the gas flow path in a liquid (water) state. If the water accumulates in the porous layer, the diffusivity of the fuel gas and the oxidizing gas into the catalyst electrode layer is reduced, and the cell performance may be significantly deteriorated.

Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-50819, it is possible to remove water droplets adhered to the wall surface of a flow channel provided in a separator and through which a fuel gas and an oxidizing gas flow. Is known. Specifically, as shown in FIG. 5, the separator 1 has through holes 2a and 2b for oxidizing gas and through holes 3a and 3b for heat medium corresponding to both sides of the catalyst electrode layer.
And fuel gas through holes 4a and 4b are provided at positions diagonal to each other.

On one surface 1a of the separator 1 facing the cathode-side electrode, for example, a through hole 2a for oxidant gas,
2b communicates with the horizontal flow channel groove 5a and the vertical flow channel groove 5b.
A plurality are provided orthogonal to each other. Similarly, a plurality of grooves orthogonal to each other are formed on the other surface side of the separator 1 in order to communicate the heat medium through holes 3a and 3b. In addition, in the separator 1 facing the anode-side electrode, similarly, not-shown grooves meandering orthogonally in the horizontal direction and the vertical direction are formed in order to communicate the fuel gas through holes 4a and 4b. .

[0008]

Incidentally, it is desired that this type of fuel cell be mounted on a vehicle body such as an automobile and used. At that time, it is most practical to install the fuel cell under the floor of the car, but it is not preferable that the height of the car rises in order to secure a sufficient living space in the cabin. Therefore, it is necessary to set the height direction of the entire fuel cell low.

However, in the above-described conventional technique, the catalyst electrode layer is set in a vertically long rectangular shape, and the entire separator 1 is formed in a substantially square shape. For this reason,
If an attempt is made to lower the height direction of the separator 1, the area of the catalyst electrode layer becomes considerably small, so that the stack electrode area cannot be effectively secured, and it becomes difficult to obtain desired power generation performance. It is pointed out. Therefore, for example, it is conceivable to arrange a plurality of fuel cell stacks side by side, but there is a problem that the structure becomes complicated and it is not economical.

The present invention solves this kind of problem. For example, a fuel that can effectively reduce the height dimension when mounted on a vehicle and can reliably obtain a desired power generation performance with a simple configuration. It is intended to provide a battery stack.

[0011]

In the fuel cell stack according to the first aspect of the present invention, the plane of the separator is set in a rectangular shape, and the short side of the plane is arranged to be directed in the direction of gravity. For this reason, the height direction of the entire fuel cell stack can be effectively reduced, and the layout can be easily performed while maintaining the desired power generation performance. Thus, for example, when the fuel cell stack is disposed under the floor of the vehicle body when mounted on a vehicle, it is possible to effectively prevent the vehicle height from increasing and secure a living space.

Further, the fluid passage provided in the plane of the separator is formed in a meandering shape extending along the long side direction in the plane and turning back on the short side. Therefore, the water generated in the fluid passage moves smoothly in the direction of gravity via the fuel gas or the oxidizing gas flowing through the fluid passage, and the water can be reliably discharged from the fuel cell stack. .

In the fuel cell stack according to the present invention, the fluid passage has a plurality of flow grooves communicating from the fluid inlet to the fluid outlet in a plane, and the flow grooves are elongated by a predetermined number. It is divided into a plurality in the side direction and meanders in the direction of gravity within each divided range. Thus, even when the area of the separator is increased in order to increase the area of the stack electrode, the flow path length is prevented from becoming long, and the gas concentration in the plane of the separator can be made uniform. . Therefore, it is possible to prevent a decrease in output density due to non-uniform gas concentration.

Further, in the fuel cell stack according to the third aspect, a fluid inlet and a fluid outlet for a cooling medium, a fuel gas and an oxidizing gas are provided at both ends on the short side of the separator. For this reason, the height direction of the separator can be effectively shortened, and the height of the entire fuel cell stack can be set lower.

Further, in the fuel cell stack according to the fourth aspect, the passage for the fluid is set so that the opening area of the passage becomes smaller from the fluid inlet to the fluid outlet. Therefore, when the fuel gas or the oxidizing gas supplied to the fluid passage is consumed in the plane of the separator, the flow passage opening area becomes narrower toward the fluid outlet, so that the unit area per unit area on the fluid outlet side is reduced. The number of reactive molecules does not decrease as compared with the fluid inlet side, and the reaction can be made uniform within the electrode surface.

Further, in the fuel cell stack according to the fifth aspect, the number of fluid passages is reduced on the fluid outlet side, for example, by adjusting the depth of a groove formed in the separator, and It is possible to set the thickness of the separator as thin as possible, as compared with a configuration that reduces the thickness.

[0017]

FIG. 1 is an exploded perspective view of a main part of a fuel cell stack 10 according to an embodiment of the present invention.
FIG. 1 is a schematic vertical sectional view of the fuel cell stack 10.

The fuel cell stack 10 includes a unit fuel cell 12 and first and second separators 14 and 16 sandwiching the unit fuel cell 12, and a plurality of these units are stacked as needed. I have. The fuel cell stack 10 has a rectangular parallelepiped shape as a whole. For example, when mounted on a vehicle, the short side direction (arrow A direction) is oriented in the direction of gravity, and the long side direction (arrow B direction) is oriented in the horizontal direction. Placed.

The unit fuel cell 12 has a solid polymer electrolyte membrane 18, an anode 20 and a cathode 22 disposed with the electrolyte membrane 18 interposed therebetween. The cathode-side electrode 22 has first and second gas diffusion layers 24 and 26 made of, for example, porous carbon paper as a porous layer.
Is arranged.

First and second gaskets 28, 30 are provided on both sides of the unit fuel cell 12, and the first gasket 28 is large for accommodating the anode 20 and the first gas diffusion layer 24. While having an opening 32, the second gasket 30 has a large opening 34 for accommodating the cathode-side electrode 22 and the second gas diffusion layer 26. Unit fuel cell 12 and first and second units
The gaskets 28, 30 are sandwiched between the first and second separators 14, 16.

As shown in FIGS. 1 and 3, the first separator 14 has a surface (plane) facing the anode 20.
14a and the opposite surface (plane) 14b are set in a rectangular shape, and when mounted on a vehicle, the long side 35a is oriented in the horizontal direction and the short side 35b is oriented in the direction of gravity. The ratio between the long side 35a and the short side 35b is, for example, 1.
It is set at 5 to 3: 1, more preferably about 2: 1.

A fuel gas inlet 36a for passing a fuel gas such as hydrogen gas and an oxidizing gas such as oxygen gas or air are passed through the upper portion of both ends on the short side 35b side of the first separator 14. And an oxidizing gas inlet 38a. A cooling medium inlet 40a and a cooling medium outlet 40b for allowing a cooling medium such as pure water or ethylene glycol to pass therethrough are provided substantially at the center of both ends of the first separator 14 on the short side 35b side. A fuel gas outlet 36b and an oxidizing gas outlet 38b are provided diagonally with respect to the fuel gas inlet 36a and the oxidizing gas inlet 38a below both ends of the separator 14 on the short side 35b side.

On the surface 14a of the first separator 14, a fuel gas passage (fluid passage) 42 communicating with the fuel gas inlet 36a and the fuel gas outlet 36b is formed. The fuel gas passage 42 has a plurality of, for example, twelve first gas passage grooves 4.
4a to 44l, and the first gas passage grooves 44a to 44l
l communicates with the fuel gas inlet 36a,
The first gas passage grooves 44a to 441 are the first separator 1
4 temporarily extends in the long side direction (the direction of arrow B), and is divided into a plurality of, for example, two groups in the long side direction.

Specifically, the first gas passage grooves 44a to 44a
f extends from the fuel gas inlet 36a to the vicinity of the oxidant gas inlet 38a, while the first gas flow grooves 44g to 441 extend to the vicinity of a substantially central portion of the first separator 14 in the long side direction (hereinafter, referred to as a central portion P). Extend. First gas channel groove 44a
To 44f are shown in FIG. 3 from the central portion P in the surface 14a.
The short side 3 extends in the direction of arrow B within the middle and right divided areas.
It is provided in the direction of gravity along the meandering shape folded back on the 5b side. The first gas passage grooves 44a to 44f are joined two by two on the way to provide second gas passage grooves 46a to 46c, and the second gas passages 46a to 46c are similarly moved in the direction of the arrow B. After directing, turning back on the short side 35b side and meandering in the direction of gravity, it communicates with the fuel gas outlet 36b.

The first gas passage grooves 44g to 44l
a, from the central portion P, it is directed in the direction of the arrow B within the divided range on the left side in FIG.
Meander in the direction of gravity. First gas passage grooves 44g to 44l
Are merged two by two on the way, and the second gas passage groove 46 d
To 46f, and the second gas passage grooves 46d to 46f are provided.
f is directed in the direction of arrow B, turns back on the short side 35b side, extends in the direction of gravity while meandering, and
Communicate with

As shown in FIG.
On the surface 14b opposite to 4a, cooling medium flow paths (fluid passages) 48a to 48f are provided so as to communicate with the cooling medium inlet 40a and the cooling medium outlet 40b. Coolant flow path 48
a to 48f respectively have one main flow channel 50a, 50b communicating with the cooling medium inlet 40a and the cooling medium outlet 40b.
b, and a plurality of, for example, four branch flow grooves 51 provided between the main flow grooves 50a and 50b.

As shown in FIG. 1, the second separator 16 is formed in a rectangular shape. The fuel gas inlet 52a and the oxidizing gas inlet A cooling medium inlet 56a and a cooling medium outlet 56b are formed through the center of both ends of the cooling medium 54a. Second separator 1
6, a fuel gas outlet 52b
The oxidizing gas outlet 54b is formed so as to penetrate the fuel gas inlet 52a and the oxidizing gas inlet 54a at a diagonal position.

The cathode electrode 22 of the second separator 16
As shown in FIG. 2, an oxidizing gas passage (fluid passage) 58 that connects the oxidizing gas inlet 54a and the oxidizing gas outlet 54b is formed on the surface 16a facing the oxidizing gas. The oxidizing gas flow path 58 includes first gas flow grooves 60a to 60l and second gas flow grooves 61a to 61f, similarly to the fuel gas flow path 42, and a detailed description thereof will be omitted.

As shown in FIG. 1, a cooling medium inlet 56 is provided on a surface 16b of the second separator 16 opposite to the surface 16a.
a and a cooling medium flow path 62a-
62f is formed. The cooling medium flow paths 62a to 62f
Coolant flow path 48 provided in first separator 14
It has the same configuration as a to 48f, and the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

The operation of the fuel cell stack 10 according to the present embodiment configured as described above will be described below.

The fuel cell stack 10 is supplied with a fuel gas (for example, a gas containing hydrogen obtained by reforming a hydrocarbon), and is supplied with air (or oxygen gas) as an oxidant gas. Is introduced from the fuel gas inlet 36 a of the first separator 14 into the fuel gas flow channel 42. As shown in FIG. 3, the fuel gas supplied to the fuel gas flow channel 42 is introduced into the first gas flow channel grooves 44 a to 44 l and is directed in the long side direction (the direction of the arrow B) of the surface 14 a of the first separator 14. It moves in the direction of gravity while meandering along.

Specifically, the first gas passage grooves 44a to 44a
The fuel gas introduced into the fuel gas f extends along the long side direction to the vicinity of the oxidizing gas inlet 38a, then turns back on the short side 35b side, and turns back near the central portion P of the surface 14a to meander in the direction of gravity. I do. For this reason, the fuel gas is
After moving while meandering in the gravitational direction within the 1/2 divided range of a, it is introduced into the second gas passage grooves 46a to 46c and sent out to the fuel gas outlet 36b. At this time, while the hydrogen gas in the fuel gas is supplied to the anode 20 of the unit fuel cell 12 through the first gas diffusion layer 24, the unused fuel gas is supplied to the second gas passage grooves 46a to 46c. Through the fuel gas outlet 36b.

On the other hand, the fuel gas introduced into the first gas passage grooves 44g to 44l is turned back at the central portion P in the surface 14a. Then, the fuel gas is の of the surface 14a.
Extends along the long side direction (the direction of arrow B) and is folded back on the short side 35b side, is supplied to the anode side electrode 20 while meandering in the direction of gravity, and is connected to the fuel gas outlet 36b. Unused parts are discharged.

In the second separator 16, the air supplied from the oxidizing gas inlet 54a to the oxidizing gas flow path 58 meanders in the direction of gravity in each of the two areas divided in the long side direction of the surface 16a. While moving. At this time, the oxygen gas in the air is supplied from the second gas diffusion layer 26 to the cathode 22 in the same manner as the fuel gas supplied to the fuel gas flow path 42, while the unused air is supplied to the oxidant gas outlet. It is discharged from 54b.

Further, a cooling medium is supplied to the fuel cell stack 10, and the cooling medium is supplied to the cooling medium inlets 40 a and 56 a of the first and second separators 14 and 16. As shown in FIG. 4, the cooling medium supplied to the cooling medium inlet 40a of the first separator 14 is introduced into each of the main flow grooves 50a that form the cooling medium flow paths 48a to 48f, and flows along the main flow grooves 50a. Flows upward, horizontally and downward. The cooling medium is introduced into the plurality of branch flow grooves 51 branched from the respective main flow grooves 50a, and flows in the horizontal direction along substantially the entire surface of the surface 14b along the branch flow grooves 51. The coolant is discharged from the cooling medium outlet 40b through the main flow channel 50b where the flow channel 51 joins.

On the other hand, the cooling medium supplied to the cooling medium inlet 56a of the second separator 16 is supplied to the cooling medium passages 62a to 62a.
After moving linearly over substantially the entire surface 16b through the passage 62f, it is discharged from the cooling medium outlet 52b.

In this case, in this embodiment, as shown in FIG. 1, the unit fuel cell 12 and the first and second separators 14, 16 are set in a rectangular shape.
The ratio of the long side to the short side is set, for example, to 1.5 to 3: 1, and more preferably to about 2: 1. The fuel cell stack 10 is formed by stacking the fuel cell stack 10 with the short sides thereof oriented in the direction of gravity, and the fuel cell stack 10 is mounted on, for example, a vehicle body (not shown).

Therefore, the size of the fuel cell stack 10 in the height direction is greatly shortened. When the fuel cell stack 10 is arranged under the floor of the vehicle body, the height of the fuel cell stack 10 is prevented from increasing and the living space is prevented. Can be effectively secured. In addition, since the unit fuel cells 12 are configured to be long in the horizontal direction, there is an effect that a desired power generation performance can be reliably obtained by securing the stack electrode area.

Further, for example, the fuel gas flow channel 42 provided on the surface 14a of the first separator 14 extends in the long side direction (the direction of arrow B) and turns back on the short side 35b side to meander in the direction of gravity. The shape is set. Therefore, water generated in the fuel gas flow path 42 easily moves in the direction of gravity,
It is possible to reliably drain the water from the surface 14a of the first separator 14.

The fuel gas passage 42 has twelve first gas passages.
Gas flow grooves 44a to 44l are divided into six gas flow grooves 44a to 44l, and the first gas flow grooves 44a to 44f
a is provided in the direction of gravity while meandering in the divided area on one side from the central portion P of the first gas flow channel groove 44g.
To 441 are provided in the direction of gravity while meandering from the central portion P along the other divided range. This reduces the length of the flow path by half compared to a structure in which the first gas flow grooves 44a to 44l are guided to the fuel gas outlet 36b while meandering continuously along the surface 14a. The density can be made uniform, and a decrease in output density can be effectively prevented.

Moreover, the first gas passage grooves 44a to 44l
Are merged two by two on the way to form the second gas flow channel groove 46a.
After that, it is connected to the fuel gas outlet 36b. Therefore, when the fuel gas flowing from the fuel gas inlet 36a to the fuel gas outlet 36b is consumed, the number of reactive molecules per unit area on the fuel gas outlet 36b side is prevented from decreasing, and the reaction in the electrode surface is prevented. Is achieved.
Here, the thickness of the first separator 14 can be reduced as compared with the conventional configuration in which the channel opening area is changed by changing the depth of the groove, and the size of the entire fuel cell stack 10 can be easily reduced. Can be

Further, the fuel gas inlet 36a, the oxidizing gas inlet 38a, the cooling medium inlet 40a, and the fuel gas outlet 3
6b, oxidant gas outlet 38b and cooling medium outlet 40b
Are provided at both ends of the first separator 14 on the short side 35b side. Therefore, the short side 35 of the first separator 14
The dimension b can be effectively shortened, and the dimension of the entire fuel cell stack 10 in the height direction can be set small.

In this embodiment, the first separator 1
4 is divided into two in the long side direction and the first gas passage grooves 44a to 44f and 44g to 441
However, the surface 14a may be divided into three or more according to the size of the surface 14a in the long side direction or the like. Further, the second separator 16 is the same as the first separator 14 described above. The fuel cell stack 10
Can be effectively placed in various installation places according to the application, in addition to being mounted on a vehicle.

[0044]

In the fuel cell stack according to the present invention, the height dimension of the entire fuel cell stack can be set small. For example, the fuel cell stack can be effectively used under the floor of a vehicle body without increasing the vehicle height when mounted on a vehicle. Can be installed. Moreover,
Since the separator has a long shape in the horizontal direction, it is possible to secure a sufficient stack electrode area and reliably obtain desired power generation performance with a simple configuration. Furthermore, since the fluid passage provided in the separator is set in a meandering shape that extends along the long side direction in the plane and turns back on the short side side, the generated water in the fluid passage is smoothly and reliably. Can be discharged to the outside.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a fuel cell stack according to an embodiment of the present invention.

FIG. 2 is a schematic longitudinal sectional explanatory view of the fuel cell stack.

FIG. 3 is an explanatory front view of one surface of a first separator constituting the fuel cell stack.

FIG. 4 is an explanatory front view of the other surface of the first separator.

FIG. 5 is an explanatory front view of a separator constituting a fuel cell according to a conventional technique.

[Explanation of symbols]

Reference Signs List 10 fuel cell 12 fuel cell 14, 16 separator 18 solid polymer electrolyte membrane 20 anode electrode 22 cathode electrode 35a long side 35b short side 36a, 52a fuel gas inlet 36b, 52b Fuel gas outlets 38a, 54a: Oxidizing gas inlets 38b, 54b: Oxidizing gas outlets 40a, 56a: Cooling medium inlets 40b, 56b: Cooling medium outlets 42: Fuel gas flow paths 44a to 44l, 46a to 46f, 60a to 60l , 6
1a to 61f: gas flow channel grooves 48a to 48f: cooling medium flow channel 58: oxidizing gas flow channel

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Narutoshi Sugita 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 5H026 AA06 CC03 CC08 CC10

Claims (5)

[Claims] 1. A fuel cell stack in which a plurality of unit fuel cells each having an electrolyte sandwiched between an anode electrode and a cathode electrode are stacked with a separator interposed therebetween, wherein the separator has a rectangular plane. A fluid passage for flowing a fluid containing at least one of a fuel gas supplied to the anode electrode and an oxidant gas supplied to the cathode electrode is provided on the plane; The fuel cell stack, wherein the fluid passage is set in a meandering shape extending along the long side direction in the plane and turning back on the short side side. 2. The fuel cell stack according to claim 1, wherein the fluid passage has a plurality of flow grooves communicating from a fluid inlet to a fluid outlet in the plane, and the flow groove has a predetermined shape. The fuel cell stack is divided into a plurality of pieces by the number of pieces in the long side direction and meanders in the direction of gravity within each of the divided ranges. 3. The fuel cell stack according to claim 1, wherein a cooling medium for cooling the unit fuel cell, the fuel gas, and the oxidizing gas are provided at both ends on the short side of the separator. A fuel cell stack, characterized in that a respective fluid inlet and a fluid outlet are provided. 4. The fuel cell stack according to claim 1, wherein the fluid passage is set such that a flow passage opening area decreases from the fluid inlet to the fluid outlet. A fuel cell stack, characterized in that: 5. The fuel cell stack according to claim 4, wherein the number of the fluid passages is reduced on the fluid outlet side.