WO2005076395A1

WO2005076395A1 - Fuel cell

Info

Publication number: WO2005076395A1
Application number: PCT/JP2004/019842
Authority: WO
Inventors: Takeharu Kuramochi; Masahiko Katsu; Kaoru Eguchi; Masahiro Omata; Yoshiki Muto
Original assignee: Nissan Motor Co., Ltd.
Priority date: 2004-02-05
Filing date: 2004-12-28
Publication date: 2005-08-18
Also published as: JP2005222809A

Abstract

A fuel cell (30) wherein catalyst layers (1b, 1c) are provided on both sides of an electrolytic membrane (1a), gas diffusion layers (4a, 4b) are provided outside the catalyst layers (1b, 1c), reaction gases such as hydrogen gas and air are supplied through gas passages (10, 11) to the gas diffusion layers (4a, 4b), the gas diffusion layers (4a, 4b) have wavy cross-sections, and the gas passages (10, 11) and the gas diffusion layers (4a, 4b) are partitioned by corrugated sheets (2, 3). Communication holes (8) are formed in the corrugated sheets (2, 3). Therefore, the thickness of the fuel cell (30) is small and uniform supply of the gasses to the gas diffusion layers (4a, 4b) is achieved.

Description

Specification

TECHNICAL FIELD The present invention relates to a configuration of a gas diffusion layer and a gas passage of a fuel cell. BACKGROUND OF THE INVENTION JP H06-283177A issued by the JPO in 1994 teaches that the separator of a fuel cell is made of a metal member with a rectangular cross section, and the inside is reinforced with a corrugated panel. The anode side separator and the anode or anode gas diffusion layer are partitioned by a flat anode current collector plate having many pores. Numerous pores are formed in the anode current collector plate, and the anode gas is supplied to the anode from the anode gas passage formed in the separator through these pores. The interior of the separator on the cathode side is divided by a panel with a corrugated section, and the separator and the power sword or power sword are separated by a flat cathode current collector that ties the string. A large number of pores are formed in the power source current collector plate, and anode gas is supplied to the anode from the cathode gas passage formed in the separator through these pores.

On the other hand, JP12003-109648A issued by the Japan Patent Office in 2003 has a contact surface with the anode or anode gas diffusion layer at the separator and the force source or force gas diffusion layer at the separator. It teaches that each contact surface is made of a corrugated sheet. An anode gas passage is formed between the corrugated plate and the anode, and a force sword gas passage is formed between the corrugated plate and the force sword. DISCLOSURE OF THE INVENTION In the former prior art, the supply of anode gas to the anode can be made uniform by changing the number of pores, for example, at the upstream and downstream of the anode gas passage. However, when a flat anode current collector and a cathode current collector are used to form a fuel cell stack by stacking fuel cells, it is inevitable that the dimension in the stacking direction of the stack increases.

In the latter prior art, the anode gas is in direct contact with the anode or anode gas diffusion layer, and similarly the force gas gas flies directly into the force gas or cathode gas expansion. Further, a coolant passage is formed inside the corrugated plate.

In this configuration, instead of using the anode current collector and the cathode current collector as in the former prior art, the corrugated plate is used on the outer surface of the separator to reduce the axial direction of the separator. The thickness increases, and consequently the stack dimension in the stacking direction also increases. Since the anode gas is in direct contact with the anode or the anode gas diffusion layer, it is difficult to equalize the supply of the anode gas to the anode at the upstream portion and the downstream portion of the anode gas passage. The same applies to the supply of force gas.

It is therefore an object of the present invention to uniformly supply anode gas to the anode or uniformly supply force gas to the force sword while suppressing the thickness of the fuel cell.

In order to achieve this object, the present invention relates to a fuel cell for generating electricity by an electric power generation reaction through a gas catalyst, wherein a gas passage through which a gas flows and a gas in the gas passage are transmitted to the catalyst. A gas diffusion layer is provided in contact with the catalyst, and a corrugated plate defining the gas diffusion layer and the gas passage is provided. The corrugated plate has a plurality of communication holes for guiding gas from the gas passage to the gas diffusion layer.

Details of the invention, as well as other features and advantages, will be set forth in the following description of the specification. Brief description of the drawings shown in the attached drawings

FIG. 1 is a perspective view of a fuel cell stack using the fuel cell according to the present invention.

FIGS. 2A-2E are exploded schematic perspective views of the fuel cell.

FIG. 3 is a cross-sectional view of a main part of the fuel cell stack.

FIG. Is a partial sectional view of a membrane electrode assembly constituting a fuel cell.

FIG. 5 is a cross-sectional view of a main part of the fuel cell, illustrating a variation of the shape of the communication hole according to the present invention.

FIG. 6 is a cross-sectional view of a main part of a fuel cell stack according to a second embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of the drawings, a fuel cell stack 100 includes a stack of a number of fuel cells 30, a current collector 101, an insulating plate 102, and an end plate 103 disposed at both ends thereof, respectively. A tie rod port 104 is provided for penetrating and fastening these.

The end plate 103 has a supply port 105A and a discharge port 105B for hydrogen gas, a supply port 106A and a discharge port 106B for air, a supply port 107A and a discharge port 107B for cooling water, respectively.

Referring to FIG. 3, the fuel cell 30 includes a membrane electrode assembly (MEA) 1 and a pair of separators 31 and 32 sandwiching the MEA 1.

Referring to FIG. 4, the MEA 1 is formed by integrally forming a catalyst layer lb, lc and a gas diffusion layer 4a, 4b on both surfaces of an electrolyte membrane la held inside a resin frame 20, respectively. The catalyst layers lb and lc contain a catalyst such as platinum, and are coated on both sides of the electrolyte membrane la using a method such as coating. Formed. The catalyst layer lb formed on one side of the electrolyte membrane la constitutes the anode of the fuel cell, and the catalyst layer lc formed on the other side constitutes the power source of the fuel cell.

The gas diffusion layer 4a contacts the anode catalyst layer lb, and the gas diffusion layer 4b contacts the cathode catalyst layer lc.

The surface of the gas diffusion layer 4a in contact with the catalyst layer lb is flat, but the opposite surface is wavy. Similarly, the surface of the gas diffusion layer 4b in contact with the catalyst layer lc is flat, but the surface on the opposite side is wavy. The gas diffusion layers 4a and 4b are made of carbon paper having such a cross-sectional shape whose main component is carbon. The gas diffusion layers 4a and 4b are bonded to the catalyst layers lb and lc, respectively, and then integrated with the electrolyte membrane 1a and the catalyst layers lb and lc by applying a heat treatment.

Referring to FIG. 2C, the gas diffusion layer 4a is formed in a rectangular planar shape having the same dimensions as the catalyst layer lc, and is located at the center of the electrolyte membrane 1a having a somewhat larger rectangular planar shape. The plurality of parallel thin lines of the gas diffusion layer 4a in the figure indicate the direction of the groove formed by the gas diffusion layer 4a having a corrugated cross section. The planar shape of the gas diffusion layer 4b is the same as the gas diffusion layer 4a, and the gas diffusion layer 4b is formed symmetrically with the gas diffusion layer 4a with the electrolyte membrane 1a interposed therebetween.

On the frame 20 holding the electrolyte membrane la, a supply manifold 105c and a discharge manifold 105d for hydrogen gas as an anode gas are formed. Similarly, a supply manifold 106c and a discharge manifold 106d for the air as the power source gas are formed. Further, similarly, the supply of the cooling liquid and the lined manifolds 107c and 107d are formed. Further, through holes 104 a of the evening port 104 are formed at the four corners of the frame 20. As shown in FIG. 3, the manifolds 105c, 105d, 106d, 106d, 107c, 107d are hermetically sealed by a seal member 21 sandwiched between the frame 20 and the separators 31, 32.

The anode separator 31 facing the gas diffusion layer 4a includes a metal flat plate 5a shown in FIG. 2A and a metal corrugated plate 2 shown in FIG. 2B.

Referring to FIG. 2A, the flat plate 5a has a hydrogen gas supply manifold 105c. A discharge manifold 105d, an air supply manifold 106c, a discharge manifold 106d, a coolant supply manifold 107c and 107d, and four through holes 104a are formed.

Referring to FIG. 2B, the corrugated plate 2 includes a corrugated portion 2a facing the gas diffusion layer 4b and a flat portion 2b around the corrugated portion 2a. As shown in FIG. 3, the corrugated portion 2a has a corrugated cross section corresponding to the corrugated cross section of the gas diffusion layer 4b. The corrugated portion 2a is formed in the center of the corrugated plate 2 by press shaping in advance.

The flat section 2b has the same hydrogen gas supply manifold 105c and discharge manifold 105d as the flat plate 5a, the air supply manifold 106c and the discharge manifold 106d, and the coolant supply manifold 107c. And 107d and four through holes 104a. Further, the flat portion 2b is provided with a connection passage 105e for connecting the hydrogen supply manifold 105c and the upstream end of the hydrogen gas passage 10 formed inside the plurality of parallel grooves of the corrugated portion 2b. You. In addition, a connection path 105f that connects the downstream end of the hydrogen gas path 10 and the hydrogen discharge manifold 105d is formed. The flow of hydrogen gas formed by the supply manifold 105c, the connection passage 105e, the hydrogen gas passage 10, the connection passage 105f, and the discharge manifold 105d is sealed by the seal member 22 sandwiched between the flat plate 5a and the corrugated plate 2. . Similarly, the air supply manifold 106c and the discharge manifold 106d, and the coolant supply manifold 107c and the discharge manifold 107d are hermetically sealed by the seal member 22 sandwiched between the flat plate 5a and the corrugated plate 2. . The outer dimensions of the flat plate 5a and the corrugated plate 2 are the same as the outer dimensions of the frame 20.

Numerous communication holes 8 are formed in the corrugated portion 2a. At this time, the cross-sectional area of the communication hole 8 per unit area of the corrugated portion 2a is increased toward the downstream of the hydrogen gas passage 10. Here, the number of communication holes 8 per unit area of the corrugated portion 2a is increased toward the downstream of the hydrogen gas passage 10. Instead of keeping the number of the communication holes 8 per unit area of the corrugated portion 2a constant, the diameter of the communication holes 8 may be increased toward the downstream of the hydrogen gas passage 10.

Referring to FIG. 3, the hydrogen gas in the hydrogen gas passage 10 is supplied through the communication hole 8 to the gas diffusion layer 4a. Supplied to Hydrogen gas permeates the gas diffusion layer 4a to reach the anode, and generates electricity by causing an electrochemical reaction with oxygen in the air supplied to the force sword through the electrolyte membrane la. Since the hydrogen gas is consumed in this manner, the hydrogen concentration in the hydrogen gas passage 10 decreases as going downstream. By increasing the cross-sectional area of the communication hole 8 per unit area of the corrugated portion 2a toward the downstream of the hydrogen passage 10, the amount of hydrogen supplied to the gas diffusion layer 4a is made uniform over the entire length of the hydrogen passage 10. I do.

The force sword separator 32 facing the gas diffusion layer 4b includes a metal flat plate 5b shown in FIG. 2E and a metal corrugated plate 3 shown in FIG. 2D.

The flat plate 5b has the same specifications as the flat plate 5a on the anode side. The corrugated plate 3 includes a press-formed corrugated portion 3a and a flat portion 3b located on the periphery thereof, similarly to the corrugated plate 2 on the anode side. An air passage 11 is formed instead of the hydrogen gas passage 10 inside the plurality of parallel grooves of the corrugated portion 3a. In the flat part 3b, similarly to the flat part 2a of the corrugated plate 2, the supply manifold 105c and the discharge manifold 105d for the hydrogen gas, the air supply manifold 106c and the discharge manifold 106d, and the supply of the coolant are provided. Manifolds 107c and 107d and four through holes 104a are formed. Further, a connection path 10e connecting the air supply manifold 106c and the upstream end of the air passage 11 and a connection path 106f connecting the air discharge manifold 106d and the downstream end of the air passage 11 are provided. , Formed instead of the connecting paths 105e and 105f. In FIG. 2D, since these passages are formed on the back surface of the corrugated plate 3, they are shown by broken lines in the figure.

The air flow formed by the air supply manifold 106c, the connection passage 106e, the air passage 11, the connection passage 106f, and the discharge manifold 106d is sealed by the seal member 22 sandwiched between the flat plate 5b and the corrugated plate 3. Is done. The hydrogen supply manifolds 105c and 105d and the coolant supply manifold 107c and the discharge manifold 107d are similarly sealed by the seal member 22 sandwiched between the flat plate 5b and the corrugated plate 3. External dimensions of flat plate 5b and corrugated plate 3 The method is the same as the external dimensions of the frame 20.

A large number of communication holes 8 are formed in the air passage 11 of the corrugated portion 3a. At this time, the cross-sectional area of the communication hole 8 per unit area of the corrugated portion 3a is increased toward the downstream of the air passage 11. Here, the number of the communication holes 8 per unit area of the corrugated portion 3a is increased toward the downstream of the air passage 11. Instead of keeping the number of the communication holes 8 per unit area of the corrugated portion 3a constant, the diameter of the communication holes 8 may be increased toward the downstream of the air passage 11.

Referring to FIG. 3, the air in the air passage 11 is supplied to the gas diffusion layer 4b through the communication hole 8. The air passes through the gas diffusion layer 4b to reach a force sword, and oxygen in the air reacts with protons that have passed through the electrolyte membrane 1 to generate water. Due to the oxygen being consumed in the power sword in this manner, the air passage 11 has a lower oxygen concentration downstream. By increasing the cross-sectional area of the communication hole 8 per unit area of the corrugated portion 3a downstream of the air passage 11, the amount of oxygen supplied to the gas diffusion layer 4b is made uniform over the entire length of the air passage 11.

Various variations are possible for the shape of the through hole 8 formed in the corrugated portions 2a and 3a. For example, as shown in FIG. 5, it is also preferable that the cross section of the through hole 8 is tapered from the entrance to the exit.

Comparing the separators 31 and 32, the only difference is that the hydrogen gas passage 10 is formed in the separator 31 and the air passage 11 is formed in the separator 32, and other configurations are the same. The configuration of these passages 10 and 11 depends exclusively on the arrangement of the sealing member 22. In other words, the separator 31 can be used as the separator 32, or vice versa, simply by changing the arrangement of the seal member 22. Such high commonality of the components of Separe Ito 31 and Separe Ito 32 is preferable in facilitating the production of the fuel cell 30 and reducing the production cost. The stacked body of the fuel cells 30 constituting the fuel cell stack 100 is formed by stacking the fuel cells 30 configured as described above as shown in FIG. As shown in FIG. 3, the flat plate 5a is used as a flat plate 5b of another adjacent fuel cell 30 as a flat plate. The rat plate 5b is used as the flat plate 5a of another adjacent fuel cell 30. That is, one flat plate is shared by the two fuel cells 30 as the flat plates 5a and 5b.

Further, in this embodiment, as shown in FIG. 3, one cooling layer 9 is provided for every two fuel cells 30. The cooling layer 9 comprises coolant passages 9a and 9b bisected by a plate 15 of corrugated cross section sandwiched between flat plates 5a and 5b. The coolant is supplied to the coolant passages 9a and 9b from a coolant supply manifold 107c. The coolant passage 9 a mainly cools the fuel cell 30 above the cooling layer 9. The coolant passage 9b mainly cools the fuel cell 30 below the cooling layer 9. The coolant flowing down the coolant passages 9a and 9b is collected in a coolant discharge manifold 107d.

The layout of the cooling layer 9 can be arbitrarily changed as needed. For example, by alternately stacking the fuel cells 30 and the cooling layers 9, higher cooling performance can be obtained.

As described above, in the fuel cell 30, the gas diffusion layer 4a is formed in a corrugated cross section, and the gas diffusion layer 4a and the hydrogen gas passage 10 are defined via the corrugated plate 2 having the corrugated portion 2a of the same cross section. In addition, as it goes downstream of the hydrogen gas passage 10, the cross-sectional area of the communication hole 8 per unit area of the corrugated portion 2a or 3a is increased, so that the thickness of the separator 31 is not increased, and the gas diffusion layer 4a is Supply of hydrogen gas can be made uniform.

Similarly, in the fuel cell 30, the gas diffusion layer 4b is formed in a corrugated cross section, and the gas diffusion layer 4b and the air passage 11 are defined through the corrugated plate 3 having the corrugated portion 3a of the same cross section. As going downstream of 11, the cross-sectional area of the communication hole 8 per unit area of the corrugated section 2a or 3a was increased, so that air was supplied to the gas diffusion layer 4b without increasing the thickness of the separator 32. It can be made uniform.

Furthermore, the structural strength of the fuel cell 30 can be increased by the corrugated sheets 2, 3, and 15. Further, the gas diffusion layer a having the corrugated cross section is engaged with the corrugated portion 2a, and the gas diffusion layer 4b having the corrugated cross section is correlated with the corrugated portion 3a. The function of preventing the slippage of the separation 31 and 32 and the MEA 1 during stacking.

Therefore, according to the present invention, a fuel cell 30 which is thin, has high power generation efficiency, and is structurally stable can be obtained.

In this embodiment, both the gas diffusion layer 4a on the anode side and the gas diffusion layer 4b on the force side have a corrugated cross section, and the corrugated plates 2 and 3 define a hydrogen gas passage 10 and an air passage 11. It goes without saying that a corresponding effect can be obtained even when the above configuration is applied to only one of the gas diffusion layer 4a on the node side and the gas diffusion layer 4b on the cathode side.

Next, a second embodiment of the present invention will be described with reference to FIG.

This embodiment is different from the first embodiment in the configuration of the coolant passage. That is, in the first embodiment, all of the plurality of grooves defined in the corrugated plate 2 and the flat plate 5 are the hydrogen gas passages 10, but in this embodiment, the hydrogen gas passages 10 are alternately arranged in every other row. A coolant passage 12 is formed. Similarly, air passages 11 and coolant passages 12 are formed in the grooves defined in the corrugated plate 3 and the flat plate 5 every other row. For this purpose, seal members 13 are arranged at the respective contacts of the corrugated plate 2 and the flat plate 5 and at the respective contacts of the corrugated plate 3 and the flat plate 5. The communication hole 8 is formed only on the surface of the corrugated portion 3a facing the air passage 11.

The coolant is supplied to the coolant passage 12 from a coolant supply manifold 107c. The coolant flowing down the coolant passage 12 is collected in a coolant discharge manifold 107d.

According to this embodiment, since the independent cooling layer 9 becomes unnecessary, the thickness of the fuel cell stack 100 can be further reduced.

The contents of Japanese Patent Application No. 2004-029565, filed on February 5, 2004, are hereby incorporated by reference.

As described above, the present invention has been described through some specific embodiments, but the present invention is not limited to the above embodiments. Those skilled in the art can make various modifications or changes to these embodiments within the scope of the claims. As described above, the present invention has been described through some specific embodiments, but the present invention is not limited to the above embodiments. Those skilled in the art can make various modifications or changes to these embodiments within the scope of the claims. As described above, according to the present invention, the gas diffusion layer and the gas passage are defined by the corrugated plate having the communication holes, so that the reaction gas can be supplied to the anode or the power source while suppressing the thickness of the fuel cell. It can be supplied uniformly. The use of corrugated plates also improves the structural stability of the fuel cell. Therefore, the present invention contributes to realization of a small and powerful fuel cell stack particularly suitable for mounting on a vehicle.

The exclusive properties or features encompassed by embodiments of the present invention are claimed as follows.

Claims

The scope of the claims

1. In a fuel cell (30) that generates power by an electrochemical reaction through a gas catalyst;

Gas passages (10, 11) for flowing gas;

A gas diffusion layer (4a, 4b) for transmitting the gas in the gas passage (10, 11) to the catalyst;

Corrugated plates (2, 3) that define gas diffusion layers (4a, 4b) and gas passages (10, 11), and gas diffusion layers from gas passages (10, 11) A plurality of communication holes (8) for guiding gas to (4a, 4b) are formed; and

Is provided.

2. The fuel cell (30) according to claim 1, wherein the gas passage (10, 11) is formed inside a groove formed by one surface of the corrugated plate (2, 3), and the gas diffusion layer (4a , 4b) are located inside the groove formed by the other side of the corrugated plate (2, 3).

3. In the fuel cell (30) according to claim 1, the cross-sectional area of the communication hole (8) per unit area of the corrugated sheet (2, 3) goes downstream of the gas passage (10, 11). Increase with time.

4. In the fuel cell (30) according to claim 3, the number of the communication holes (8) per unit area of the corrugated sheet (2, 3) increases as going downstream of the gas passages (10, 11). To increase.

5. In the fuel cell (30) according to claim 1, the cross-sectional area of the communication hole (8) gradually increases from the gas passage (10, 11) toward the gas diffusion layer (4a, 4b). .

6. The fuel cell (30) according to claim 1, wherein the corrugated sheet (30) (2, 3) is made of conductive material

7. The fuel cell according to claim 1, wherein the gas diffusion layer (4a, 4b) is preliminarily fitted so as to fit inside a groove formed by one surface of the corrugated plate (2, 3). It is composed of a carbon paper formed in a corrugated cross section.

8. The fuel cell (30) according to any one of claims 1 to 7, wherein the fuel cell (30) includes a catalyst layer (lb, lc) containing a catalyst on both sides of the electrolyte membrane (la). It further comprises a membrane electrode assembly (1) formed on both sides, and the gas diffusion layers (4a, 4b) are arranged between the catalyst layers (lb, lc) and the corrugated plates (2, 3).

9. The fuel cell (30) according to claim 8, wherein the fuel cell (30) includes a corrugated plate (2, 3) and a flat plate (5a, 5b) in contact with the corrugated plate (2, 3). The separated separation (31, 32) and gas passages (10, 11) are further defined by corrugated plates (2, 3) and flat plates (5a, 5b). , 32) are laminated on the membrane electrode assembly (1) with the corrugated plates (2a, 3a) in contact with the gas diffusion layers (4a, 4b).

10. In the fuel cell (30) according to claim 9, the flat plate (5) is made of a metal plate, and the corrugated plates (2, 3) press the corrugated portions (2a, 3a) in advance. It is composed of a molded metal plate.

11. In the fuel cell (30) according to claim 9, the catalyst layer (lb, lc) includes an anode catalyst layer (lb) formed on one side of the electrolyte membrane (la) and the other side. A cathode catalyst layer (lc) formed on the surface, the gas diffusion layers (4a, 4b), the anode gas diffusion layer (4a) in contact with the anode catalyst layer (lb), and the force catalyst layer (lc). Contacting with a sword gas diffusion layer (4b) In the evening (31, 32), the anode separator (31) in contact with the anode gas diffusion layer (4a) through the corrugated plate (2) and the force in contact with the force gas diffusion layer (4b) through the corrugated plate (3) The gas passages (10, 11) are formed inside the anode separator (1) and supply the anode gas to the anode gas diffusion layer (4a). ), And a power sword gas passage (11) formed inside the power sword separator (32) and supplying the power sword gas to the cathode gas diffusion layer (4b).

12. The fuel cell (30) according to claim 11, wherein the fuel cell (30) includes a membrane electrode assembly (1), an anode-side separator (31), and a force-side separator 2). And an anode gas exhaust manifold, an anode gas exhaust tl manifold, a power source gas ^ manifold, and a power source gas exhaust manifold. A connection path (105e) connecting the anode gas passage (10) to the anode gas supply manifold; and a connection path (10f) connecting the anode gas passage (10) to the anode gas discharge manifold. The one-way separator (32) has a connection (106e) connecting the cathode gas passage (11) to the power sword gas supply manifold and a connection (106f) connecting the power sword gas passage (11) to the power sword gas discharge manifold. ) And It provided La.

13. The fuel cell (30) according to claim 12, wherein the anode separator (31) includes a sealing member (22) arranged so as to define two connection paths (105e, 105ί). In addition, the force separation separator (32) further comprises a sealing member (22) arranged to define two connection paths (105e, 105ί), respectively.

14. In the fuel cell 0) according to claim 13, the configuration of the anode separator (31) and the configuration of the cathode separator (32) are the same except for the arrangement of the seal member 1).

15. In the fuel cell (30) according to claim 9, the separator (31, 32) is provided with corrugated plates (2, 3) and flat plates (5a, It further comprises a coolant passage (12) defined in 5b).

16. In the fuel cell (30) according to claim 12, the separator (31, 32) is provided with a corrugated plate to cut off the gas passage (10, 11) and the coolant passage (12) from each other. It further comprises a seal member (13) sandwiched between the (2, 3) and the flat plates (5a, 5b).