JPH10162842A - Separator for solid high polymer fuel cell nd solid high polymer fuel cell stack using this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently cool a fuel cell stack, and make the whole compact in the thickness of a device by projecting a heat radiating fin to a side edge part of a separator main body having a gas passage which contacts electrodes arranged on both sides by sandwiching a solid high polymer electrolyte film and supplies gas. SOLUTION: A separator main body part 10 for a solid high polymer fuel cell is formed into a rectangular plate shape by a conductive material, and a groove-shaped gas passage 15 for hydrogen gas and oxygen gas is arranged in its both surface center part. Gas supply-discharge holes 13 and 14 for hydrogen gas and oxygen gas are respectively arranged in two places in diagonal line positions on the outer peripheral side, and the passage 15 is communicated with the hole 14. A heat radiating fin 11 plays a role to radiate heat of a separator main body part 10, and is formed by projecting from one side of an outer peripheral side edge part of the separator main body part 10, and the fin 11 is formed thinner than the separator main body part 10. A separator 1 is composed of a metallic material, and is large in heat conductivity, and the heat in the main body part 10 is quickly transmitted to the fin 11, and cooling is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte fuel cell separator and a polymer electrolyte fuel cell stack using the same.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional separator for a polymer electrolyte fuel cell, and FIG. 6 shows a structure of a cell of a polymer electrolyte fuel cell stack constituted by using the conventional separator. In a conventional polymer electrolyte fuel cell, FIG.
As shown in (1), the separator 1 has a main body formed of a conductive material in a flat plate shape, and has gas flow paths 12 and 15 for hydrogen gas and oxygen gas at the center of both surfaces of the main body, respectively. Gas supply / discharge holes 13 and 14 for hydrogen gas and oxygen gas are provided in the section, respectively, and a refrigerant supply / discharge hole 16 is further provided. In the conventional polymer electrolyte fuel cell stack, as shown in FIG. 6, a hydrogen electrode 3 and an oxygen electrode 4 supported by support current collectors 5 are arranged on both sides of the polymer electrolyte membrane 2, respectively. The separators 1 and 1 are arranged on the outside, and a plurality of the stacked cells are stacked as one unit cell, and the gas supply / discharge holes 13 and 14 are connected to each other in the stacking direction. I have.

When hydrogen gas flows in from the supply side of the gas supply / discharge holes 14 and oxygen gas flows in from the supply side of the gas supply / discharge holes 13, hydrogen gas flows into the gas passage 15 of the separator 1 in contact with the hydrogen electrode 3. Gas is supplied and oxygen electrode 4
Oxygen gas is supplied to the gas flow path 12 of the separator 1 in contact with the hydrogen electrode 3, and the reaction represented by the reaction formula H ₂ → 2H ++ 2e ⁻ occurs on the hydrogen electrode 3 side, and the reaction formula 1 / 2O ₂ + 2H + 2e− → occurs on the oxygen electrode 4 side. A reaction represented by H ₂ O + reaction heat Q occurs, and a reaction represented by H ₂ + 1 / 2O ₂ → H ₂ O occurs in total. In other words, hydrogen emits electrons at the hydrogen electrode 3 to be protonated, moves to the oxygen electrode 4 side through the polymer electrolyte layer 2, and receives electrons at the oxygen electrode 4 to react with oxygen. The electromotive force is generated for each fuel cell unit based on the electrochemical reaction, and a large electromotive force can be obtained in the entire fuel cell stack in which these fuel cells are stacked and connected in series. Was.

Incidentally, since the above reaction is not reversible, in the fuel cell, an overvoltage η which is an irreversible component thereof is used.
Exists. Also, because of the internal resistance R of the battery,
When the current I flows, a voltage loss of IR occurs. As a result, only the amount of ηI + I ² R + reaction heat Q becomes heat energy instead of electric power, and heats the fuel cell stack to increase the temperature.

[0005] In general, a polymer electrolyte fuel cell has an optimum operating temperature range for good power generation. However, since the amount of heat accompanying the cell reaction is large, it is necessary to stabilize the operating conditions. It was necessary to provide a cooling means.
In particular, in a polymer electrolyte fuel cell, the polymer electrolyte membrane needs to be cooled to 100 ° C. or less for operation since the polymer electrolyte membrane contains water. Therefore, conventionally, as a cooling means,
A conductive cooling plate 6 having a coolant passage 62 is interposed in part or all of the fuel cells constituting the fuel cell stack, and a coolant supply / discharge hole 66 communicating with the coolant passage 62 of the cooling plate 6 is formed. The fuel cell stack can be cooled by communicating with the coolant supply / discharge holes 16 of the separator 1 in the stacking direction and passing a coolant such as water through the coolant supply / discharge holes 16.

However, in this case, since the cooling plate 6 is interposed in the stacking direction, the thickness of the fuel cell stack is increased by that amount, which hinders the compactness in the thickness direction. Further, the cooling plate 6 also functions as an electric resistance, which has been a factor of reducing the electromotive force of the entire fuel cell stack.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide good cooling of a fuel cell stack and downsizing in the thickness direction. An object of the present invention is to provide a polymer electrolyte fuel cell separator and a polymer electrolyte fuel cell stack using the same.

[0008]

According to a first aspect of the present invention, there is provided a separator for a polymer electrolyte fuel cell, comprising electrodes disposed on both sides of the polymer electrolyte membrane. In contact with the side edge of the separator body having a gas flow path for supplying hydrogen gas or oxygen gas to the electrode,
The radiating fin is provided in a protruding manner.

A separator for a polymer electrolyte fuel cell according to a second aspect is the separator for a polymer electrolyte fuel cell according to the first aspect, wherein the separator main body and the radiation fins are integrally formed of a metal material; It is characterized in that a conductive corrosion prevention coating is formed on the surface.

According to a third aspect of the present invention, there is provided a separator for a polymer electrolyte fuel cell according to the second aspect, wherein the metal material is aluminum.

According to a fourth aspect of the present invention, there is provided a separator for a polymer electrolyte fuel cell according to the second or third aspect, wherein the corrosion prevention coating is made of titanium, titanium carbide, titanium nitride, Or a carbon film.

According to a fifth aspect of the present invention, there is provided the separator for a polymer electrolyte fuel cell according to the first aspect, wherein the central layer of the separator main body and the radiation fins are integrally formed of a metal plate. And the surface layer portion in which the gas flow path of the separator main body is formed is formed by joining a conductive material sheet having punched holes corresponding to the gas flow path to both surfaces of the central layer portion. Is what you do.

According to a sixth aspect of the present invention, there is provided the separator for a polymer electrolyte fuel cell according to the fifth aspect, wherein the metal plate is an aluminum plate.

According to a seventh aspect of the present invention, there is provided a polymer electrolyte fuel cell stack, wherein the separator according to any one of the first to sixth aspects is arranged outside the electrodes arranged on both sides of the solid polymer electrolyte membrane. It is characterized in that a plurality of stacked cells are stacked.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a separator for a polymer electrolyte fuel cell according to an embodiment of the present invention. Also,
FIG. 4 is an exploded perspective view showing a cell structure of a polymer electrolyte fuel cell stack configured using the separator according to the embodiment. The separator 1 for a polymer electrolyte fuel cell according to the embodiment has a configuration in which a radiation fin 11 is protruded from a side edge of a separator body 10.

The separator body 10 is formed of a conductive material in a rectangular flat plate shape, and has groove-shaped gas flow paths 12 and 15 for hydrogen gas and oxygen gas at the center of both surfaces thereof, and has an outer peripheral side. Gas supply / discharge holes 13 and 14 for hydrogen gas and oxygen gas
There are two places. The gas flow passage 12 is provided with
The gas passage 14 communicates with the gas supply / discharge hole 15. In the present invention, the separator body 10
The size is not particularly limited, and the design can be changed according to the purpose, and the planar shape can be variously changed according to the purpose.

The radiating fins 11 are connected to the separator body 1.
It plays a role of dissipating heat of 0, and in this embodiment, is formed so as to protrude from one side of the outer peripheral edge of the separator main body 10. Further, the radiation fins 11 are formed thinner than the thickness of the separator body 10.

In the present invention, the size of the radiation fin 11 is not particularly limited, and
The design can be freely changed so that a desired heat radiation effect can be obtained according to the heat exchange efficiency with the heat exchange medium that radiates heat upon contact. As a specific example, for example, when the size of the separator body 10 is 100 mm × 100 mm, the size of the heat radiation fins 11 may be about 100 mm × 50 mm.

The position where the radiation fins 11 protrude from the separator body 10 is not particularly limited.
As shown in (1), the projection may be provided on two sides of the outer peripheral side edge of the separator body 10, or may be provided on the entire outer peripheral edge. Increasing the projecting position from the separator body 10 is effective in increasing the fin surface area and improving the heat exchange efficiency. It is also advantageous to uniformly and uniformly radiate heat from the separator body 10.

In the separator 1 according to this embodiment, the separator main body 10 and the radiation fins 11 are integrally formed of aluminum or the like, and a conductive corrosion prevention coating is formed on the surface thereof. Since the separator 1 is formed of a metal material, the heat conductivity is increased as compared with the case where the separator 1 is formed using carbon or the like, and the heat of the separator body 10 is quickly transferred to the radiation fins 11 to improve the cooling effect. It will be. In particular, aluminum is lightweight, has excellent workability, and is superior in strength to carbon materials. Therefore, the thickness of the separator 1 can be reduced as a whole, which is advantageous for downsizing in the thickness direction. is there. In addition, since aluminum is inferior in weather resistance to carbon material, the surface of the separator 1 is coated with a corrosion prevention coating to compensate for this. It is necessary to form the corrosion prevention coating with a material having excellent corrosion resistance and conductivity, and examples thereof include titanium, titanium carbide, titanium nitride, and a carbon film. As a forming method thereof, for example, a sputtering method, a thermal CVD method, a plasma CVD method, an ion plating method, or the like can be used.

In the separator 1 according to this embodiment, the gas passages 12 and 15 formed in grooves on the surface layers on both surfaces of the separator main body 10 are formed in a plane to increase the gas contact area with the electrodes. Have been. As a method of forming the gas passages 12 and 15, there is a method of forming a groove by machining a flat surface of a portion corresponding to the separator main body 10 in the starting material in a flat plate shape using a counterbore processing machine or the like. . However, this method takes a lot of time and effort for processing, so that the production efficiency is poor and the mass productivity is low. On the other hand, when the separator 1 is formed by a member configuration as shown in FIG. 3, the production efficiency is improved and the mass productivity can be improved.

That is, in the separator 1 shown in FIG. 3, the central layer portion of the separator body 10 and the radiation fins 11 are integrally formed by a single metal plate 1a, and the gas passages 12, 15 of the separator body 10 are formed. The surface layer portions on both sides formed are punched holes 12 c,
The conductive material sheets 1c and 1b having the 15b are joined to both surfaces of the central layer, respectively. More specifically, the metal plate 1a is provided with holes 13 at positions corresponding to the gas supply / discharge holes 13 and 14 of the separator body 10.
a, 14a are opened, while the conductor material sheets 1c,
In 1b, punched holes 12c and 15b corresponding to the gas flow paths 12 and 15 and holes (13b and 14b) and (13c and 14c) corresponding to the gas supply / discharge holes 13 and 14 are formed in advance. Then, the separator 1 is formed by joining the conductive material sheets 1c and 1b to both sides of the metal plate 1a, respectively. As described above, since the gas flow paths 12, 15 can be easily formed by punching the relatively thin conductive material sheets 1c, 1b, the productivity is improved. Here, a lightweight aluminum plate is preferably used as the metal plate 1a, and a carbon sheet in addition to the aluminum plate can be used as the conductive material sheet 1c.

Next, the polymer electrolyte fuel cell stack shown in FIG. 4 will be described. This is manufactured using the above-described separator 1, that is, the hydrogen electrode 3 and the oxygen electrode 4 supported by the supporting current collector 5 are arranged on both sides of the solid polymer electrolyte membrane 2, respectively. The separators 1 and 1 are arranged on the outside, and a plurality of the stacked cells are stacked as one unit cell, and the gas supply / discharge holes 13 and 14 are connected to each other in the stacking direction.

As the solid polymer electrolyte membrane 2, one having a substituent such as a sulfonic acid group as an electrolyte is used. Examples of the oxygen electrode 4 and the hydrogen electrode 3 include a layer formed by supporting a platinum catalyst or the like with a supporting current collector 5 so as to have gas permeability.

When the hydrogen gas flows in from the supply side of the gas supply / discharge holes 14 and the oxygen gas flows in from the supply side of the gas supply / discharge holes 13, the gas flow of the separator 1 in contact with the hydrogen electrode 3 The hydrogen gas is supplied to the passage 15 and the gas passage 12 of the separator 1 is in contact with the oxygen electrode 4.
At this time, hydrogen is released from the hydrogen electrode 3 and protonated, and moves to the oxygen electrode 4 side through the solid polymer electrolyte layer 2. An electromotive force is generated for each fuel cell unit based on an electrochemical reaction in which the fuel cell is supplied and reacts with oxygen. In the entire fuel cell stack in which these fuel cells are stacked and connected in series, a large electromotive force is generated. Power is obtained.

The hydrogen gas supplied at this time may be hydrogen gas alone, but usually, a reformed gas containing hydrogen generated by reforming methanol or butane gas by a fuel reformer is used. used. Although oxygen alone may be used as the oxygen gas, air is usually used.

When the fuel cell stack is operated as described above, it generates an electromotive force and generates heat. However, since the separator 1 having the radiating fins 11 is used, this heat is radiated through the separator body 10. The heat is transmitted to the fins 11 and is radiated from the radiating fins 11 to a heat exchange medium such as air. As a result, the fins 11 are cooled to a temperature range where stable operation is possible. Therefore, it is possible to omit the cooling plate conventionally used to be interposed in the fuel cell stack, and the thickness can be reduced accordingly. Further, since the cooling plate can be omitted, a device for supplying a refrigerant and the like are not required, and the whole fuel cell can be made compact.

[0029]

As described above, according to the separator for a polymer electrolyte fuel cell according to the present invention, the heat generated during the operation of the fuel cell can be radiated to the outside of the system from the radiation fins through the separator body. Conventionally, it is possible to omit a cooling plate required for cooling. As a result, the fuel cell stack using the separator can reduce the heat generated during operation and reduce the thickness thereof. Further, conventionally, a device for supplying a coolant to the cooling plate becomes unnecessary, and the fuel cell as a whole can be made compact.

In the separator for a polymer electrolyte fuel cell according to the present invention, the separator body and the radiation fin are integrally formed of a metal material, and the surface thereof is provided with a conductive corrosion prevention coating. Then, the thermal conductivity of the separator is increased, the heat dissipation effect is improved, and the corrosion resistance is also favorably maintained by the corrosion prevention coating. In this case, if the metal material is aluminum,
It is effective and preferable for weight reduction.

Further, the separator has a central layer portion of the separator main body and a radiation fin integrally formed of a metal plate, and a surface layer portion in which a gas flow path of the separator main body is formed is connected to the gas flow path. When the conductor material sheet having the punched holes corresponding to the above is formed by bonding to both surfaces of the central layer portion, the labor for forming the gas flow path is not required, and as a result, the manufacturing cost can be reduced. .

Since the polymer electrolyte fuel cell stack according to the present invention is constituted by using the separator according to the present invention, cooling of the heat generated during operation without the interposition of a cooling plate can be performed by the separator. This can be done by the radiation fins provided in the. Therefore, compactness is possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a polymer electrolyte fuel cell separator according to an embodiment of the present invention.

FIG. 2 is a perspective view showing another embodiment of the separator for a polymer electrolyte fuel cell according to the present invention.

FIG. 3 is a perspective view showing still another embodiment of the separator for a polymer electrolyte fuel cell according to the present invention.

FIG. 4 is an exploded perspective view showing a structure of a cell of a polymer electrolyte fuel cell stack constituted by using a polymer electrolyte fuel cell separator according to an embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional polymer electrolyte fuel cell separator.

FIG. 6 is an exploded perspective view showing a cell structure of a polymer electrolyte fuel cell stack formed using a conventional polymer electrolyte fuel cell separator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separator for polymer electrolyte fuel cells 2 Solid polymer electrolyte membrane 3 Hydrogen electrode 4 Oxygen electrode 10 Separator main body 11 Heat radiation fins 12, 15 Gas flow path

Claims (7)

[Claims] 1. A radiating fin is provided on a side edge of a separator body having a gas flow path for supplying a hydrogen gas or an oxygen gas to the electrodes, the fin being in contact with electrodes disposed on both sides of the solid polymer electrolyte membrane. A separator for a polymer electrolyte fuel cell, wherein the separator is protruded. 2. The solid polymer fuel according to claim 1, wherein the separator body and the radiating fins are integrally formed of a metal material, and a conductive anti-corrosion coating is formed on the surfaces thereof. Battery separator. 3. The separator for a polymer electrolyte fuel cell according to claim 2, wherein the metal material is aluminum. 4. The separator for a polymer electrolyte fuel cell according to claim 2, wherein the corrosion prevention coating is a titanium, titanium carbide, titanium nitride, or carbon film. 5. The center layer of the separator body and the radiating fins are integrally formed by a metal plate, and the surface layer portion of the separator body where the gas flow path is formed is punched corresponding to the gas flow path. 2. The separator for a polymer electrolyte fuel cell according to claim 1, wherein a conductive material sheet having holes is formed by bonding to both surfaces of the central layer. 6. The separator for a polymer electrolyte fuel cell according to claim 5, wherein the metal plate is an aluminum plate. 7. A plurality of cells comprising the separator according to any one of claims 1 to 6 arranged and laminated outside electrodes arranged on both sides of the solid polymer electrolyte membrane. A polymer electrolyte fuel cell stack characterized by the above-mentioned.