JP2003338299A - Fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable supplying evenly and satisfactorily a reaction gas along the whole power generation plane in a simple and a small configuration. <P>SOLUTION: A fuel battery 10 has a first and a second separators 16, 18 sandwiching an electrolyte membrane/electrode structure 14. The first separator 16 has an oxidant agent gas flow path 38 on a plane 16a opposite to a cathode side electrode 36. The gas flow path 38 has a first and a second oxidant agent gas flow path areas 40a, 40b; and a first and a second buffer parts 42a, 42b for supplying the oxidant agent gas into the path areas 40a, 40b communicated with one communicating hole 20 on an oxidant agent gas supplying side. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte / electrode structure having electrodes provided on both sides of an electrolyte, and a pair of separators for sandwiching the electrolyte / electrode structure. The invention relates to a fuel cell provided with: 2. Description of the Related Art For example, a polymer electrolyte fuel cell has an electrolyte membrane comprising a polymer ion exchange membrane (cation exchange membrane) and an anode electrode and a cathode electrode provided on both sides of the electrolyte membrane. (Electrolyte membrane)-It is constituted by sandwiching the electrode structure with a separator. This type of fuel cell is usually used as a fuel cell stack by laminating a predetermined number of electrolyte / electrode structures and separators. [0003] In this fuel cell, a fuel gas supplied to the anode side electrode, for example, a gas mainly containing hydrogen (hereinafter also referred to as a hydrogen-containing gas), is ionized on the catalyst electrode and passes through the electrolyte. To the cathode side. The electrons generated during that time are taken out to an external circuit and used as DC electric energy. An oxidant gas, for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas) is provided on the cathode side electrode.
Is supplied, hydrogen ions, electrons and oxygen react at the cathode side electrode to generate water. In the above-described fuel cell, a fuel gas flow path (reactive gas flow path) through which fuel gas flows in the plane of the separator facing the anode electrode, and an oxidizing gas flow path facing the cathode electrode. And an oxidizing gas flow path (reactive gas flow path) through which the gas flows. Furthermore, in this type of fuel cell, a communication hole for flowing the oxidizing gas and the fuel gas, which are the reaction gas, into the reaction gas flow path is formed inside the fuel cell by penetrating the electrolyte / electrode structure and the separator in the stacking direction. A manifold is used. In this case, in order to maintain a desired power generation function, it is necessary to supply a fuel gas and an oxidizing gas over the entire power generation surface of the anode electrode and the cathode electrode within the surfaces of the respective separators. For this reason, in the separator, a long fuel gas flow path and an oxidizing gas flow path are provided so as to meander, or a fuel gas flow path and an oxidizing gas flow path including a large number of flow grooves are provided. Or [0006] However, it is extremely difficult to uniformly supply a reaction gas from a communication hole formed in the separator to a reaction gas flow path provided in the surface of the separator over the entire power generation surface. As a result, there is a problem in that the reaction gas is not sufficiently supplied particularly to a portion separated from the communication hole, and the distribution of the reaction gas becomes uneven, thereby increasing the concentration overvoltage. Therefore, in order to solve this kind of problem,
For example, a current collector plate of a polymer electrolyte fuel cell disclosed in JP-A-2001-250568 is known. In this prior art, as shown in FIG. 7, fuel gas passages 2a and 2b, which are vertically divided into two, are provided on one of the laminated surfaces of the current collector plate 1 facing a cathode (not shown). Similarly, an oxidizing gas passage (not shown), which is divided into upper and lower parts, is formed on the other laminated surface of the current collecting plate 1 facing the anode (not shown). A fuel gas passage 2 is provided at one end of the current collector plate 1.
a, which is a supply-side communication hole for supplying fuel gas to
And second intake holes 3a, 3b, first and second exhaust holes 4c, 4d, which are discharge-side communication holes for discharging an oxidizing gas from an oxidizing gas passage (not shown), and a water supply hole 5a. ing. At the other end of the current collector plate 1, first and second exhaust holes 3c and 3d, which are discharge-side communication holes for discharging fuel gas from the fuel gas passages 2a and 2b, and an oxidizing gas passage (not shown). First and second intake holes 4a and 4b, which are supply side communication holes for supplying the oxidizing gas, and a drain hole 5b are formed. The fuel gas passages 2a and 2b have a plurality of parallel grooves 6a and 6b extending linearly in the horizontal direction from the first and second intake holes 3a and 3b, and the first and second exhaust holes 3a.
c, buffer portions (lattice grooves) 7a, 7b adjacent to the 3d side
These form a predetermined channel groove. First and second
Buffer portions (space portions) 7c and 7d are also provided on the intake holes 3a and 3b corresponding to the ends of the parallel grooves 6a and 6b. As described above, the current collector plate 1 is provided with the fuel gas passages 2a and 2b which are vertically divided into two parts, that is, the fuel gas passages 2a and 2b are narrowed in the vertical direction. First and second intake holes 3a and 3b for supplying fuel gas to the fuel cell, and first and second exhaust holes 3c and 3d for discharging fuel gas from the fuel gas passages 2a and 2b.
Are provided. Therefore, the first and second intake holes 3
The fuel gas can be satisfactorily supplied from a, 3b along the fuel gas passages 2a, 2b, and the distribution of the fuel gas can be improved over the entire power generation surface of the current collector plate 1. However, in the above-mentioned prior art, two supply side communication holes (first and second intake holes 3a, 3b) are provided for supplying fuel gas, Two discharge side communication holes (first and second exhaust holes 3c and 3d) are provided for discharging the fuel gas. Further, two supply-side communication holes (first and second intake holes 4a and 4b) are provided for supplying the oxidant gas, and two discharge-side communication holes (first port) for discharging the oxidant gas. And second exhaust holes 4c, 4d). As a result, it has been pointed out that the number of communication holes for supplying and discharging the reaction gas is doubled as compared with the conventional configuration, and that the manifold becomes large and complicated. In addition, in the seal member for sealing the communication hole, the seal portion increases, and the seal area increases. For this reason, there is a problem that the utilization rate of the electrode surface decreases. The present invention solves this kind of problem, and an object of the present invention is to provide a fuel cell capable of uniformly and favorably supplying a reaction gas along the entire power generation surface with a simple and small configuration. Aim. [0014] In the fuel cell according to the first aspect of the present invention, the reaction gas flow path formed in the surface of the separator facing the electrolyte / electrode structure is provided with the separator in the laminating direction. At least a reaction gas that is an oxidizing gas or a fuel gas is supplied from a supply-side communication hole provided therethrough, and the reaction gas flow path has at least two divided reaction gas flow path areas; At least two buffer units that communicate with the supply-side communication holes and supply the reaction gas to the divided reaction gas flow path regions. As described above, at least two buffer portions are provided for one supply-side communication hole. Therefore, as compared with the conventional configuration in which the separator is provided with two pairs of supply-side communication holes and two buffer portions, it is possible to reduce the size and simplification of the manifold while securing the same distribution of the reactive gas, and to achieve a sealing area. Is reduced. Thereby, the utilization rate of the electrode surface is effectively improved. FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to a first embodiment of the present invention, and FIG.
FIG. 2 is a partial cross-sectional view of the fuel cell 10. The fuel cell 10 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 14 and first and second separators 16, 1
8 is provided. A seal member 19 such as a gasket is interposed between the electrolyte membrane / electrode structure 14 and the first and second separators 16 and 18 to cover the periphery of a communication hole described later and the outer periphery of the electrode surface (power generation surface). Is equipped. One end edge in the direction of arrow B (horizontal direction in FIG. 1) intersecting the laminating direction (direction of arrow A in FIG. 1) of the electrolyte membrane / electrode structure 14 and the first and second separators 16 and 18 , An oxidizing gas supply side communication hole 20 for supplying an oxidizing gas, for example, an oxygen-containing gas, extends in the direction of arrow C (vertical direction in FIG. 1). Provided. First and second fuel gas discharge side communication holes 22a and 22b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided on both upper and lower sides of the oxidant gas supply side communication hole 20.
Is provided. At the other end of the electrolyte membrane / electrode structure 14 and the first and second separators 16 and 18 in the direction of arrow B,
A fuel gas supply-side communication hole 24 for supplying fuel gas is provided extending in the direction of arrow C (vertical direction in FIG. 1), communicating with each other in the direction of arrow A. First and second sides for discharging the oxidizing gas are provided on both upper and lower sides of the fuel gas supply side communication hole 24.
And second oxidant gas discharge side communication holes 26a and 26b are provided. At the lower end edges of the electrolyte membrane / electrode structure 14 and the first and second separators 16 and 18, a cooling medium supply side communication hole 28 for supplying a cooling medium such as pure water, ethylene glycol or oil is provided. Is provided, and a cooling medium discharge side communication hole 30 for discharging the cooling medium is provided at the upper edge. The electrolyte membrane / electrode structure 14 includes, for example, a solid polymer electrolyte membrane (electrolyte) 32 in which a thin film of perfluorosulfonic acid is impregnated with water, and an anode side sandwiching the solid polymer electrolyte membrane 32. An electrode 34 and a cathode-side electrode 36 are provided. The anode-side electrode 34 and the cathode-side electrode 36 are a gas diffusion layer made of carbon paper or the like, and an electrode catalyst in which porous carbon particles having a platinum alloy supported on the surface are uniformly coated on the surface of the gas diffusion layer. Layers. As shown in FIGS. 1 and 3, an oxidizing gas flow for supplying an oxidizing gas along the cathode 36 is provided on a surface 16 a of the first separator 16 facing the cathode 36. A passage (reaction gas passage) 38 is formed. The oxidizing gas flow path 38 includes a plurality of, for example, two divided first and second oxidizing gas flow path areas (reaction gas flow path areas) 40a and 40b, and one supply-side communication hole oxidizing. First and second buffer sections 42a and 42b are provided to supply the oxidizing gas to the first and second oxidizing gas passage areas 40a and 40b in communication with the chemical gas supply side communication hole 20. The first and second oxidizing gas passage areas 40a,
40b is provided with a predetermined number of straight flow paths 44a, 44b each extending in parallel with the direction of arrow B. Straight channel 4
The upstream ends of the first and second buffer units 4a and 44b
It communicates with the oxidant gas supply side communication hole 20 via 2a and 42b. The downstream ends of the straight flow paths 44a, 44b communicate with the first and second oxidizing gas discharge side communication holes 26a, 26b via the third and fourth buffer portions 42c, 42d.
In the first to fourth buffer units 42a to 42d, for example,
Each has an embossed portion 46. As shown in FIG. 4, a fuel gas flow path (reaction gas flow) for supplying fuel gas along the anode 34 is provided on a surface 18a of the second separator 18 facing the anode 34. A path 48 is formed. The fuel gas flow path 48 includes a plurality of, for example, first and second fuel gas flow path areas (reaction gas flow path areas) 50a and 50 divided into two.
b and the first and second fuel gas passage areas 50 communicating with the fuel gas supply side communication hole 24 which is one supply side communication hole.
a and 50b for supplying fuel gas to the first and second buffers 52a and 52b. The first and second fuel gas passage areas 50a, 5a
0b has a predetermined number of straight flow paths 54a, 54b extending in parallel to the direction of arrow B, respectively. Straight channel 54
a, 54b are connected to the first and second buffer units 52
a and 52b communicates with the fuel gas supply side communication hole 24. The downstream ends of the straight flow paths 54a and 54b communicate with the first and second fuel gas discharge side communication holes 22a and 22b via the third and fourth buffer portions 52c and 52d. The first to fourth buffer sections 52a to 52d are provided with, for example, emboss sections 56, respectively. As shown in FIGS. 1 and 5, a cooling medium flow path 58 is provided on a surface 18b of the second separator 18 opposite to the surface 18a. The cooling medium flow path 58 is provided with a predetermined number of straight flow paths 60 extending parallel to the vertical direction (the direction of arrow C). Both ends of the straight flow path 60 communicate with the coolant supply side communication hole 28 and the coolant discharge side communication hole 30. An opening 6 corresponding to the anode 34 and the cathode 36 is formed at the center of the seal member 19.
2 are formed (see FIG. 1). The operation of the fuel cell 10 thus configured will be described below. As shown in FIG. 1, inside the fuel cell 10,
A fuel gas such as a hydrogen-containing gas, an oxidizing gas such as air that is an oxygen-containing gas, and a cooling medium such as pure water, ethylene glycol, and oil are supplied. The oxidizing gas supplied to the oxidizing gas supply side communication hole 20 communicating in the direction of arrow A is supplied to the first separator 16 as shown in FIGS.
Is introduced into the oxidizing gas flow path 38 of FIG. Specifically, the oxidant gas supply side communication hole 20
Are connected to first and second buffer portions 42a and 42b constituting an oxidizing gas flow channel 38. The first and second buffer portions 42a and 42b are connected to the first and second buffer portions 42a and 42b from the oxidizing gas supply side communication hole 20. An oxidant gas is supplied. The first and second buffer sections 42a and 42b communicate with the first and second oxidizing gas flow path areas 40a and 40b. For this reason, the oxidizing gas is supplied to the first and second oxidizing gas flow paths 4.
0a, 40b each provided in the straight flow path 44
a, moves in the direction of arrow B1 via 44b, and
It is supplied along the cathode electrode 36 constituting the electrode structure 14. On the other hand, as shown in FIG. 4, the fuel gas is introduced into the fuel gas passage 48 from the fuel gas supply side communication hole 24 communicating in the direction of arrow A. This fuel gas flow path 48
Is provided with first and second buffer portions 52a and 52b communicating with the fuel gas supply side communication hole 24, and the fuel gas is supplied to the first and second buffer portions 52a and 52b via the first and second buffer portions 52a and 52b. The fuel gas is supplied to the fuel gas passage regions 50a and 50b. The fuel gas is supplied to the respective straight flow paths 54 forming the first and second fuel gas flow areas 50a and 50b.
It moves in the direction of arrow B2 (the direction opposite to the direction of arrow B1) along the lines a and b, and is supplied along the anode 34 constituting the electrolyte membrane / electrode structure 14. Therefore, in each of the electrolyte membrane / electrode structures 14, the oxidizing gas supplied to the cathode 36 and the fuel gas supplied to the anode 34 are subjected to an electrochemical reaction in the electrode catalyst layer. It is consumed and power is generated (see FIG. 2). Next, the oxidant gas supplied to the cathode electrode 36 and consumed is supplied to the third and fourth buffer units 4.
The gas is discharged to the first and second oxidizing gas discharge side communication holes 26a and 26b through the holes 2c and 42d (see FIG. 3). Similarly, the fuel gas supplied to and consumed by the anode 34 is supplied to the first and second fuel gas discharge side communication holes 22a, 22b via the third and fourth buffer units 52c, 52d.
(See FIG. 4). As shown in FIGS. 1 and 5, the cooling medium supplied to the cooling medium supply side communication hole 28 is introduced into the cooling medium passage 58 of the second separator 18. This cooling medium moves vertically upward along the straight flow path 60,
After cooling the electrolyte membrane / electrode structure 14, the electrolyte membrane / electrode structure 14 is discharged to the cooling medium discharge side communication hole 30. In this case, in the first embodiment, as shown in FIG. 3, the oxidizing gas channel 38 formed on the surface 16a of the first separator 16 is divided into at least two first and second oxidizing gas channels 38. The first and second oxidizing gas passage areas 40a and 40b communicate with the oxidizing gas supply
First and second buffer portions 42a and 42b for supplying an oxidizing gas to the oxidizing gas flow path regions 40a and 40b are provided. As described above, at least two first and second buffer portions 42a and 42b are provided for one oxidizing gas supply side communication hole 20. At this time, the first and second buffer units 4 are connected through the oxidant gas supply side communication holes 20.
Since the ends of the first and second oxidizing gas supply passages 20a and 40b are separated from the oxidizing gas supply side communication hole 20, the oxidizing gas is sufficiently supplied to the ends of the first and second oxidizing gas flow areas 40a and 40b. Supplied. For this reason, the oxidizing gas is supplied from the oxidizing gas supply side communication hole 20 to the entire first and second oxidizing gas flow path regions 40a and 40b through the first and second buffer portions 42a and 42b. Good introduction. Therefore,
The oxidizing gas can be uniformly distributed over the entire area of the oxidizing gas flow path 38, and, for example, an effect that an increase in concentration overvoltage can be effectively suppressed can be obtained. Moreover, the single oxidant gas supply side communication hole 2
The first and second buffer sections 42a and 42b communicate with the oxidizing gas supply side communication hole 20. For this reason, compared to a configuration in which the individual oxidizing gas supply side communication holes communicate with the first and second buffer portions 42a and 42b, the oxidizing gas manifold can be reduced in size while securing the same oxidizing gas distribution. And simplification can be achieved, and the sealing area by the sealing member 19 is reduced. Thereby, there is obtained an advantage that the utilization factor of the electrode surface is effectively improved. On the other hand, in the second separator 18, similarly, as shown in FIG. 4, the first and second buffer portions 52a and 52b are provided so as to communicate with the single fuel gas supply side communication hole 24. . Therefore, the fuel gas can be uniformly distributed over the entire area of the fuel gas flow path 48, and the fuel gas manifold can be reduced in size and simplified to improve the utilization rate of the electrode surface. FIG. 6 is a partial front view of a first separator 70 constituting a fuel cell according to a second embodiment of the present invention. The same components as those of the first separator 16 configuring the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The surface 70a on the electrode surface side of the first separator 70
An oxidizing gas flow path (reactive gas flow path) 72 is formed in the fin. The oxidizing gas passage 72 includes a plurality of, for example, two divided first and second oxidizing gas passages (reaction gas passages) 74 a and 74 b, and the oxidizing gas supply side communication hole 2.
0 and the first and second oxidizing gas passage areas 74.
a and 74b for supplying an oxidizing gas to the first and second buffer units 76a and 76b. The first and second oxidizing gas passage areas 74a,
74b is a predetermined number of meandering flow paths 78 extending in the horizontal direction (arrow B direction) while meandering in the vertical direction (arrow C direction).
a, 78b. The upstream ends of the meandering flow paths 78a and 78b communicate with the oxidant gas supply side communication hole 20 via the first and second buffer portions 76a and 76b. The downstream ends of the meandering channels 78a, 78b communicate with the first and second oxidizing gas discharge side communication holes 26a, 26b via the third and fourth buffer portions 76c, 76d. Although not shown, a fuel gas flow path having a meandering flow path is similarly formed on the second separator 18 side. In the second embodiment configured as described above, the straight flow paths 44a and 44 used in the first embodiment are used.
b, serpentine flow paths 78a and 78b are provided, and the oxidizing gas is supplied to the first and second oxidizing gas flow paths 74.
a, and are supplied along a cathode-side electrode (not shown) while meandering along 74b. Therefore, the oxidizing gas can be supplied uniformly and reliably along the entire surface of the cathode electrode (not shown), and the same effect as in the first embodiment can be obtained. In the first and second embodiments, the first and second oxidizing gas passage regions 40a, 40a,
0b (74a, 74b) and the first and second fuel gas passage areas 50a, 50b are provided independently, but the invention is not limited to this. For example, this kind of reaction gas flow path area may be independently divided into three, four, or five or more divisions. At this time, in particular, when the number of divisions is set to an even number, the reaction in the electrode surface is easily uniformized. Although the anode 34 and the cathode 36 are each formed as a single unit, the anode 34 and the cathode 36 may be divided into a plurality of parts corresponding to the reaction gas flow path area.
This makes it possible to reduce the number of electrode materials, which is economical. In the fuel cell according to the present invention, at least two divided reaction gas passage areas and one divided reaction passage communicating with one supply side communication hole or one discharge side communication hole. At least two for supplying or discharging the reaction gas to the gas flow path area
And two buffer units. For this reason, compared with a configuration in which the separator is provided with two pairs of communication holes and buffer portions corresponding to the respective reaction gas flow path areas, the same miniaturization and simplification of the manifold is achieved while maintaining the same reaction gas distribution. And the sealing area is reduced. As a result, the utilization efficiency of the electrode surface is effectively improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a main part of a fuel cell according to a first embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the fuel cell. FIG. 3 is an explanatory front view of a first separator constituting the fuel cell. FIG. 4 is an explanatory front view of one surface of a second separator constituting the fuel cell. FIG. 5 is an explanatory front view of the other surface of the second separator. FIG. 6 is a partial front view illustrating a first separator included in a fuel cell according to a second embodiment of the present invention. FIG. 7 is an explanatory front view of a current collecting plate according to the related art. DESCRIPTION OF SYMBOLS 10 ... Fuel cell 14 ... Electrolyte membrane / electrode structure 16, 18, 70 ... Separator 19 ... Seal member 20 ... Oxygen gas supply side communication hole 22a, 22b ... Fuel gas discharge side communication hole 24 ... Fuel Gas supply side communication holes 26a, 26b ... Oxidizing gas discharge side communication hole 28 ... Cooling medium supply side communication hole 30 ... Cooling medium discharge side communication hole 32 ... Solid polymer electrolyte membrane 34 ... Anode side electrode 36 ... Cathode side electrode 38 , 72: Oxidizing gas flow paths 40a, 40b, 74a, 74b: Oxidizing gas flow path areas 42a to 42d, 52a to 52d, 76a to 76d: Buffer sections 44a, 44b, 54a, 54b, 60: Linear flow path 48 ... Fuel gas flow path 50a, 50b ... Fuel gas flow path area 58 ... Cooling medium flow path 78a, 78b ... Meandering flow path

Claims (1)

Claims: 1. An electrolyte / electrode structure having electrodes provided on both sides of an electrolyte, and a pair of separators sandwiching the electrolyte / electrode structure. In the reaction gas channel formed in the facing separator surface,
A fuel cell that supplies or discharges at least a reaction gas that is an oxidant gas or a fuel gas from a supply-side communication hole or a discharge-side communication hole that is provided to penetrate the separator in a stacking direction, wherein the reaction gas flow path is And supplying or discharging the reaction gas to the divided reaction gas flow path area by communicating with at least two divided reaction gas flow path areas and one of the supply-side communication holes or the discharge-side communication holes. A fuel cell, comprising: at least two buffer units.