JP2004311084A - Fuel cell and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable obtaining uniform surface pressure, keeping desired power generation performance and also miniaturizing and lightening, in a simple structure and process. <P>SOLUTION: A first terminal plate 20a is disposed at a recessed portion 66 placed at a central section of a first end plate 22a while forming a prescribed clearance, and a first insulating member 24a is disposed in the clearance by insert mold molding. A periphery end portion 68 of the insulating member 24a surrounds the outer periphery portion of the terminal plate 20a and covers an end face 70 with the recessed portion 66 of the end plate 22a disposed thereon. The insulating member 24a is projected toward an inner periphery face of a hole portion 72 formed at the central portion of the end plate 22a and provided with a cylindrical portion 74 circulating a power extracting terminal 52. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a fuel cell in which an electrolyte / electrode structure having a pair of electrodes provided on both sides of an electrolyte and a separator are stacked, and a terminal plate, an insulating member, and an end plate are disposed at both ends in the stacking direction, and a method of manufacturing the fuel cell. About.
[0002]
[Prior art]
For example, a polymer electrolyte fuel cell has an electrolyte membrane (electrolyte) / electrode structure in which an anode electrode and a cathode electrode are provided on both sides of an electrolyte membrane composed of a polymer ion exchange membrane (cation exchange membrane). Is sandwiched between the separators.
[0003]
In this fuel cell, a fuel gas supplied to the anode electrode, for example, a gas mainly containing hydrogen (hereinafter, also referred to as a hydrogen-containing gas) is obtained by ionizing hydrogen on the electrode catalyst and passing through the electrolyte to the cathode side. Move to the electrode side. 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, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas) is supplied to the cathode side electrode, hydrogen ions, electrons, And oxygen react to produce water.
[0004]
By the way, this type of fuel cell usually constitutes a laminate in which a predetermined number of electrolyte / electrode structures and separators are laminated, and a terminal plate for collecting power generated from each fuel cell at both ends of the laminate. The fuel cell stack is provided with an end plate for holding the laminate and the terminal plate, and an insulating plate for insulating the terminal plate and the end plate.
[0005]
For example, when this fuel cell stack is used for a vehicle, it is necessary to stack a considerably large number (for example, about several hundreds) of fuel cells in order to obtain a desired high output. Therefore, a relatively large load (inertial force) is likely to act on the fuel cell stack when the vehicle suddenly starts or stops.
[0006]
In particular, when a load acts on the fuel cell stack when the stacking direction of the fuel cell stack is set to be substantially the same as the traveling direction of the vehicle, each plate disposed at one end of the fuel cell stack in the stacking direction. The fastening pressure between the terminal plate and the insulating plate and between the insulating plate and the end plate is reduced. As a result, there is a problem that the sealing performance of the fuel gas and the cooling medium supplied into the fuel cell stack is reduced.
[0007]
Therefore, for example, a fuel cell disclosed in Patent Document 1 is employed. As shown in FIG. 6, the fuel cell includes a cell stack 3 in which a unit cell 1 and a frame 2 are stacked. A terminal portion 5 is provided between the end surface M in the laminating direction and the base plate 4. The terminal portion 5 has a conductive current collecting portion 6, one end of which is connected to the current collecting portion 6, and the other end of which passes through the through hole 4 a of the base plate 4. And a conductive rod 7 protruding outward. The current collector 6 includes a plate 8 connected to the bar 7 and having conductivity, and a flexible conductive material 9 provided between the plate 8 and the end surface M. .
[0008]
In the fuel cell configured as described above, the end faces M of the plate-shaped body 8 and the cell stack 3 are utilized by utilizing the flexibility of the flexible conductive material 9 irrespective of the inclination state, the vibration, and the like in the installation state of the fuel cell. And can be electrically connected uniformly over the entire surface.
[0009]
[Patent Document 1]
Patent No. 3111124 (paragraphs [0008] and [0021], FIG. 2)
[0010]
[Problems to be solved by the invention]
In Patent Document 1, the plate 8 is supported on the base plate 4, and the plate 8 is connected to the end surface M of the cell stack 3 via the flexible conductive material 9. However, the processing tolerance of the base plate 4 and the plate-like body 8 is accumulated at the connection portion with the end face M. As a result, a uniform surface pressure cannot be obtained on the end face M of the cell stack 3, and there is a problem that contact resistance increases and power generation performance decreases. In addition, since the frame 2 is used to form the gap, the number of parts of the entire fuel cell increases, and the fuel cell cannot be reduced in size and weight.
[0011]
The present invention is to solve this kind of problem, and it is possible to obtain a uniform surface pressure with a simple configuration and process, maintain desired power generation performance, and reduce the size and weight. It is an object of the present invention to provide a fuel cell and a method for manufacturing the same.
[0012]
[Means for Solving the Problems]
In the fuel cell according to the first aspect of the present invention and the method for manufacturing a fuel cell according to the fifth aspect, the end plate and the terminal plate are disposed with a predetermined gap therebetween, and an insert is inserted into the gap. An insulating member is provided by molding. Insert molding refers to a molding method in which a component (insert) is placed in a cavity of a mold, and the component is integrated with, for example, a plastic molded product during a molding cycle.
[0013]
For this reason, the relative position between the end plate and the terminal plate can be adjusted with high precision, avoiding accumulation of the respective processing tolerances, and ensuring uniform surface pressure on the electrode surface (power generation surface) of the fuel cell. Can be granted. Accordingly, the fuel cell can maintain desired power generation performance, and can be easily reduced in size and weight as a whole without increasing the number of parts.
[0014]
Further, in the fuel cell according to the second aspect of the present invention and the method for manufacturing a fuel cell according to the sixth aspect, the terminal plate is provided with a predetermined gap formed in the concave portion provided at the center portion of the end plate. . The peripheral portion of the insulating member surrounds the outer peripheral portion of the terminal plate and covers the end surface of the end plate where the concave portion is provided (claim 3). Therefore, it is possible to reliably prevent the terminal plate and the end plate from being electrically connected with a simple configuration and a simple process.
[0015]
Further, in the fuel cell according to claim 4 of the present invention, the terminal plate is provided with a rod-shaped power extraction terminal extending in the stacking direction and projecting from the end plate to the outside, and the end plate has the rod-shaped power extraction terminal. A tubular portion is provided around the power extraction terminal to form an insulating member. Therefore, with a simple configuration, electric power can be reliably taken out from the terminal plate, and the terminal plate and the end plate are not electrically connected.
[0016]
Furthermore, in the fuel cell manufacturing method according to claim 7 of the present invention, after the end plate, the insulating member and the terminal plate are integrated, the surface on the terminal plate side is subjected to a flattening process. . Thereby, the flatness of the terminal plate is further improved by a simple process, and a uniform surface pressure can be reliably obtained on the electrode surface (power generation surface).
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic overall configuration diagram of a fuel cell stack 10 incorporating a fuel cell according to a first embodiment of the present invention, and FIG. 2 is a partially exploded perspective view of the fuel cell stack 10.
[0018]
As shown in FIG. 1, the fuel cell stack 10 includes a laminate 18 in which a plurality of electrolyte membranes (electrolytes) / electrode structures 12 are laminated with first and second separators 14 and 16 interposed therebetween. The first and second separators 14 and 16 are formed of a metal plate or a carbon plate.
[0019]
First and second terminal plates 20a and 20b and first and second end plates 22a and 22b are provided at both ends of the stack 18 in the stacking direction (direction of arrow A) with first and second insulating members 24a and 24b. It is arranged with interposition. The first and second insulating members 24a and 24b are made of, for example, polycarbonate (PC). The first and second end plates 22a and 22b are held together by a fastening rod or the like (not shown), and a desired fastening load is applied to the entire fuel cell stack 10.
[0020]
The fuel cell 26 is constituted by the electrolyte membrane / electrode structure 12 and the first and second separators 14 and 16. As shown in FIG. 2, a gasket is provided between the electrolyte membrane / electrode structure 12 and the first and second separators 14 and 16 so as to cover the periphery of a communication hole described later and the outer periphery of an electrode surface (power generation surface). And the like are interposed.
[0021]
Oxidizing gas for supplying an oxidizing gas, for example, an oxygen-containing gas, is communicated with one end of the fuel cell 26 in the horizontal direction (the direction of arrow B in FIG. 2) in the direction of the arrow A which is the stacking direction. The agent gas supply communication hole 30a, the cooling medium discharge communication hole 32b for discharging the cooling medium, and the fuel gas discharge communication hole 34b for discharging the fuel gas, for example, the hydrogen-containing gas, are arranged in the direction of arrow C (vertical direction). Are arranged in a row.
[0022]
At the other end of the fuel cell 26 in the direction of arrow B, a fuel gas supply communication hole 34a for supplying fuel gas and a cooling medium supply communication hole for supplying a cooling medium are communicated with each other in the direction of arrow A. 32a and an oxidizing gas discharge communication hole 30b for discharging the oxidizing gas are arranged in the arrow C direction.
[0023]
The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 36 in which a thin film of perfluorosulfonic acid is impregnated with water, an anode electrode 38 and a cathode electrode 40 sandwiching the solid polymer electrolyte membrane 36. And
[0024]
The anode-side electrode 38 and the cathode-side electrode 40 are made of a gas diffusion layer made of a porous carbon member, for example, carbon paper, and a porous carbon particle having a platinum alloy supported on the surface. And an electrode catalyst layer coated on the substrate. The electrode catalyst layers are joined to both surfaces of the solid polymer electrolyte membrane 36 so as to face each other with the solid polymer electrolyte membrane 36 interposed therebetween.
[0025]
An opening 45 is formed at the center of the seal member 28 so as to correspond to the anode 38 and the cathode 40. Instead of the seal member 28, a seal may be provided on the first and second separators 14, 16 by baking or injection molding.
[0026]
On the surface 14a of the first separator 14 on the side of the cathode-side electrode 40, for example, an oxidizing gas flow path 46 including a plurality of grooves extending in the direction of arrow B is provided. And the oxidizing gas supply communication hole 30a and the oxidizing gas discharge communication hole 30b.
[0027]
A fuel gas flow path 48 communicating with the fuel gas supply passage 34a and the fuel gas discharge passage 34b is formed on the surface 16a of the second separator 16 on the side of the anode 38. The fuel gas passage 48 has a plurality of grooves extending in the direction of arrow B. On the surface 16b of the second separator 16, a cooling medium passage 50 communicating with the cooling medium supply communication hole 32a and the cooling medium discharge communication hole 32b is formed. The cooling medium flow path 50 has a plurality of grooves extending in the direction of arrow B.
[0028]
As shown in FIG. 1, a rod-shaped power extraction terminal 52 that extends in the stacking direction (the direction of arrow A) and protrudes outside from the first end plate 22a is provided at the center of the first terminal plate 20a. A hole 54 is formed through the center of the power extraction terminal 52, and a set screw member 56 is inserted into the hole 54.
[0029]
The set screw member 56 includes a large-diameter portion 56a disposed in a stepped hole portion 58 formed in the first terminal plate 20a, and has a distal end projecting outward from the distal end of the power extraction terminal 52. A screw portion 56b is provided. A lug terminal 60 is disposed on the screw portion 56b, and the lug terminal 60 is attached to the power extraction terminal 52 by screwing a nut 62 into the screw portion 56b. One end of an electric wire 64 is connected to the lug terminal 60, and the electric wire 64 is connected to an external load (not shown).
[0030]
The first end plate 22a has a concave portion 66 at the center. The first terminal plate 20a is provided in the recess 66 with a predetermined gap H1 formed therein, and the gap H1 is provided with a first insulating member 24a by insert molding.
[0031]
The peripheral end portion 68 of the first insulating member 24a surrounds the outer peripheral portion of the first terminal plate 20a and covers the end surface 70 of the first end plate 22a where the concave portion 66 is provided. The first insulating member 24a protrudes from the inner peripheral surface of a hole 72 formed at the center of the first end plate 22a, and has a cylindrical portion (cylindrical portion) 74 that goes around the power extraction terminal 52.
[0032]
The second terminal plate 20b, the second end plate 22b, and the second insulating member 24b are configured in the same manner as the first terminal plate 20a, the first end plate 22a, and the first insulating member 24a, and have the same components. Are denoted by the same reference numerals, and a detailed description thereof will be omitted.
[0033]
The manufacturing method according to the first embodiment using the fuel cell stack 10 configured as described above will be described below.
[0034]
First, as shown in FIG. 3, a first end plate 22a and a first terminal plate 20a are arranged in a molding die 80. In the molding die 80, the outer surface 82 as the reference surface of the first end plate 22a and the pressing surface 84 as the reference surface of the first terminal plate 20a are adjusted so as to be parallel to each other. The power extraction terminal 52 fits into the first terminal plate 20a, and the power extraction terminal 52 fits loosely into the hole 72 of the first end plate 22a.
[0035]
A cavity 86 is formed in the mold 80, and the cavity 86 is filled with a molten resin such as polycarbonate from an inlet 88. When the molten resin is solidified in the cavity 86, the first insulating member 24a is insert-molded. Therefore, as shown in FIG. 4, the first terminal plate 20a, the first insulating member 24a, and the first end plate 22a are integrated, and the power extraction terminal 52 is connected to the cylindrical portion 74 of the first insulating member 24a. It is held around.
[0036]
Similarly to the above, the second terminal plate 20b, the second insulating member 24b, and the second end plate 22b are integrated. After a predetermined number of fuel cells 26 are stacked between the first and second terminal plates 20a and 20b, the first and second end plates 22a and 22b are clamped and held together by a not-shown clamping rod or the like. Thus, the entire fuel cell stack 10 is manufactured.
[0037]
In this case, in the first embodiment, the first insulating member 24a is provided by insert molding in a state where the first end plate 22a and the first terminal plate 20a are relatively positioned. Therefore, the relative position between the first end plate 22a and the first terminal plate 20a can be adjusted with high precision, and the accumulation of these processing tolerances can be avoided, and the electrode surface (power generation surface) of each fuel cell 26 can be adjusted. A uniform surface pressure can be reliably applied.
[0038]
For this reason, the fuel cell stack 10 has an effect that the desired power generation performance is reliably maintained, the number of parts does not increase, and the size and weight of the entire fuel cell stack 10 can be easily reduced. .
[0039]
Further, the peripheral end portion 68 of the first insulating member 24a surrounds the outer peripheral portion of the first terminal plate 20a and covers the end surface 70 of the first end plate 22a where the concave portion 66 is provided. Therefore, the electrical connection between the first terminal plate 20a and the first end plate 22a can be reliably prevented with a simple configuration and process.
[0040]
Furthermore, the first terminal plate 20a is provided with a power extraction terminal 52 extending in the stacking direction and protruding outside from the first end plate 22a, and has an inner periphery of a hole 72 of the first end plate 22a. The surface is provided with a cylindrical portion 74 that goes around the power extraction terminal 52 and forms the first insulating member 24a. Therefore, with a simple configuration, electric power can be reliably extracted from the first terminal plate 20a, and the first terminal plate 20a and the first end plate 22a are not electrically connected.
[0041]
In the first embodiment, after the first end plate 22a, the first insulating member 24a, and the first terminal plate 20a are integrated by insert molding, the pressing surface 84 of the first terminal plate 20a includes: A flattening process is performed as necessary. Thereby, the flatness of the first terminal plate 20a is further improved by a simple process, and a uniform surface pressure can be reliably applied to the electrode surface (power generation surface) of each fuel cell 26.
[0042]
The second end plate 22b, the second insulating member 24b, and the second terminal plate 20b provide the same effects as those of the first end plate 22a, the first insulating member 24a, and the first terminal plate 20a.
[0043]
Next, the operation of the fuel cell stack 10 will be described below.
[0044]
First, as shown in FIG. 2, a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply passage 34a, and an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply passage 30a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium supply communication hole 32a.
[0045]
For this reason, the oxidizing gas is introduced from the oxidizing gas supply passage 30 a into the oxidizing gas flow channel 46 of the first separator 14 and moves along the cathode electrode 40 constituting the electrolyte membrane / electrode structure 12. . On the other hand, the fuel gas is introduced into the fuel gas passage 48 of the second separator 16 from the fuel gas supply passage 34a, and moves along the anode 38 that forms the electrolyte membrane / electrode structure 12.
[0046]
Therefore, in each electrolyte membrane / electrode structure 12, the oxidizing gas supplied to the cathode 40 and the fuel gas supplied to the anode 38 are consumed by the electrochemical reaction in the electrode catalyst layer, Power generation is performed.
[0047]
Next, the fuel gas supplied to the anode 38 and consumed is discharged in the direction of arrow A along the fuel gas discharge communication hole 34b. Similarly, the oxidant gas supplied to and consumed by the cathode electrode 40 is discharged in the direction of arrow A along the oxidant gas discharge communication hole 30b.
[0048]
The cooling medium supplied to the cooling medium supply communication hole 32a flows into the cooling medium flow path 50 of the second separator 16 and then flows in the direction of arrow B. This cooling medium is discharged from the cooling medium discharge communication hole 32b after cooling the electrolyte membrane / electrode structure 12.
[0049]
FIG. 5 is an explanatory sectional view of a main part of a fuel cell stack 90 incorporating a fuel cell according to a second embodiment of the present invention. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.
[0050]
At one end in the stacking direction of the fuel cell stack 90, a first terminal plate 20a and a first end plate 92 are disposed with a first insulating member 94 interposed therebetween. Although not shown, the other end of the fuel cell stack 90 in the stacking direction is configured in the same manner as the above-described one end in the stacking direction.
[0051]
The first end plate 92 and the first terminal plate 20a are arranged with a predetermined gap H2 therebetween, and a first insulating member 94 is provided in the gap H2 by insert molding. A peripheral end portion 96 of the first insulating member 94 surrounds an outer peripheral portion of the first terminal plate 20a.
[0052]
In the second embodiment configured as described above, the first insulating member 94 is provided by insert molding in a state where the first end plate 92 and the first terminal plate 20a are relatively positioned. Therefore, the relative position between the first end plate 92 and the first terminal plate 20a can be adjusted with high accuracy, and the desired power generation performance can be reliably maintained, and the number of components does not increase. The same effects as in the first embodiment can be obtained, for example, the size and weight of the entire fuel cell stack 90 can be easily reduced.
[0053]
【The invention's effect】
ADVANTAGE OF THE INVENTION In the fuel cell and its manufacturing method which concern on this invention, the relative position of an end plate and a terminal plate can be adjusted with high precision, the accumulation of each processing tolerance is avoided, and the electrode surface (power generation surface) of a fuel cell ) Can be given a uniform surface pressure. Thus, the fuel cell can maintain desired power generation performance, and can be easily reduced in size and weight as a whole without increasing the number of parts.
[Brief description of the drawings]
FIG. 1 is a schematic overall configuration explanatory view of a fuel cell stack incorporating a fuel cell according to a first embodiment of the present invention.
FIG. 2 is an exploded perspective view of a main part of the fuel cell stack.
FIG. 3 is an explanatory diagram when insert molding a first terminal plate, a first insulating member, and a first end plate that constitute the fuel cell;
FIG. 4 is an explanatory sectional view of the insert molded state.
FIG. 5 is an explanatory sectional view of a main part of a fuel cell stack incorporating a fuel cell according to a second embodiment of the present invention.
FIG. 6 is an exploded perspective view of a main part of a fuel cell according to Patent Document 1.
[Explanation of symbols]
10, 90: Fuel cell stack 12: Electrolyte membrane / electrode structure 14, 16: Separator 20a, 20b: Terminal plates 22a, 22b, 92: End plates 24a, 24b, 94: Insulating member 26: Fuel cell 36: Solid height Molecular electrolyte membrane 38 Anode-side electrode 40 Cathode-side electrode 46 Oxidant gas flow path 48 Fuel gas flow path 50 Coolant flow path 52 Power supply terminal 54 Hole 56 56 Set screw member 66 Recess 68 Reference numerals 96, peripheral end portion 70, end surface 74, cylindrical portion 80, molding die 86, cavity

Claims (7)

An electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte and a separator are stacked, and at both ends in the stacking direction, a terminal plate, an insulating member and an end plate are disposed, and the fuel cell is a fuel cell.
The fuel cell according to claim 1, wherein the end plate and the terminal plate are arranged with a predetermined gap therebetween, and the insulating member is provided in the gap by insert molding. 2. The fuel cell according to claim 1, wherein a concave portion is provided in a central portion of the end plate. 3. The fuel cell according to claim 2, wherein a peripheral portion of the insulating member surrounds an outer peripheral portion of the terminal plate and is configured to cover an end surface of the end plate provided with the concave portion. Fuel cell. The fuel cell according to any one of claims 1 to 3, wherein the terminal plate is provided with a rod-shaped power extraction terminal extending in the stacking direction and projecting outside from the end plate,
The fuel cell according to claim 1, wherein the end plate is provided with a tubular portion that goes around the rod-shaped power extraction terminal and forms the insulating member. An electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte and a separator are stacked, and at both ends in the stacking direction, a terminal plate, an insulating member and an end plate are provided.
A step of disposing the end plate and the terminal plate while forming a predetermined gap therebetween,
Providing the insulating member in the gap by insert molding,
A method for manufacturing a fuel cell, comprising: 6. The manufacturing method according to claim 5, wherein the terminal plate is arranged by forming the gap in a concave portion provided in a central portion of the end plate,
A method of manufacturing a fuel cell, wherein a peripheral portion of the insulating member surrounds an outer peripheral portion of the terminal plate and covers an end surface of the end plate where the concave portion is provided. 7. The manufacturing method according to claim 5, wherein after the end plate, the insulating member, and the terminal plate are integrated, a surface on the terminal plate side is subjected to a flattening process. Fuel cell manufacturing method.

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