JP2001176519A - Conductive separator, high molecular electrolyte-type fuel cell and method of manufacturing high molecular electrolyte-type fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of a high molecular electrolyte-type fuel cell by securing both a gas passage and sealing function of a separator formed of a metallic plate and an elastic material, and to reduce the number of components, the number of assembling processes and the cost in mass production. SOLUTION: This conductive separator is composed of a metallic plate having a groove or a rib for guiding a gas on its surface kept into contact with an electrode, and a sealing member forming a gas passage and inlet and outlet ports of the gas passage together with the groove or rib, and acting as a gasket for preventing leakage of the gas from the gas passage to the exterior, and the sealing member on the metallic plate is composed of plural elastic materials different from each other in hardness. The high molecular electrolytic fuel cell is manufactured by using this conductive separator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a portable power supply,
The present invention relates to a polymer electrolyte fuel cell used for a power source for an electric vehicle, a home cogeneration system, and the like, a method for producing the same, and a conductive separator used for the production.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell generates electricity and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen with an oxidizing gas containing oxygen such as air. It is. A polymer electrolyte fuel cell generally includes a proton conductive polymer electrolyte membrane, an electrode, and a conductive separator. The electrode includes a combination of a diffusion layer and a catalytic reaction layer, and the catalytic reaction layer is formed on both surfaces of the polymer electrolyte membrane that selectively transports hydrogen ions. The catalyst reaction layer is mainly composed of carbon powder carrying a platinum-based metal catalyst. On the outer surface of the catalytic reaction layer, a diffusion layer having both gas permeability and electron conductivity for the fuel gas and the oxidizing gas is formed.

[0003] In order to prevent fuel gas and oxidizing gas supplied after assembling the battery from leaking to the outside and to prevent the two types of gases from being mixed with each other around the pair of electrodes sandwiching the polymer electrolyte membrane. A seal member such as a gasket is provided with the polymer electrolyte membrane interposed therebetween. In addition, a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane before battery assembly are called an electrode electrolyte membrane assembly (MEA).

[0004] On both sides of the MEA, conductive separators for mechanically fixing the MEA and electrically connecting adjacent MEAs to each other in series are arranged. A gas flow path for supplying fuel gas and oxidizing gas to the electrode surface and carrying away generated gas and surplus gas is formed in a portion of the separator that contacts the MEA. The gas flow path can be provided as a separate component from the separator.However, there is a method in which grooves or ribs are provided on the surface of the separator by cutting the surface or pressing, etc., according to the material of the separator to form a gas flow path. General.

[0005] In order to supply the fuel gas and the oxidizing gas to the grooves or ribs, the supply pipes for the fuel gas and the oxidizing gas are branched according to the number of separators to be used. Alternatively, a piping jig communicating with the rib is required. This jig is called an external manifold, and the holes through which the fuel gas, the oxidizing gas, and the like that make up the jig flow are called the manifold holes. On the other hand, there is a so-called internal manifold type having a simpler structure. The internal manifold type is one in which a through-hole in the stacking direction is formed in a stacked body composed of a separator having gas channels and MEA, and is used as a manifold hole. Around the hole formed in each plate-shaped part, a necessary seal is provided by providing a rib, arranging an O-shaped ring, or the like. A fuel gas and an oxidizing gas supply pipe are connected to the manifold hole, and the fuel gas and the oxidizing gas are supplied directly from the hole.

[0006] Since the fuel cell generates heat during operation, it is necessary to cool the fuel cell with cooling water or the like in order to maintain the cell in a good temperature state. Therefore, usually, a cooling unit for flowing cooling water every 1 to 3 cells is provided between the separators. However, in general, a cooling water flow path is provided on the back surface of the separator to serve as a cooling unit in many cases.

[0007] The MEA, the separator and, if necessary, the cooling section are provided alternately. After stacking 10 to 200 cells, this is sandwiched between end plates via a current collector plate and an insulating plate, and fixed from both ends with fastening bolts. The structure in which the laminate is tightened is a general structure of a fuel cell.

A separator used in such a fuel cell needs to have high conductivity, high gas tightness, and high corrosion resistance to a redox reaction between hydrogen and oxygen. For this reason, conventional separators are usually made of carbon materials such as glassy carbon and expanded graphite. In addition, the gas flow path is formed by cutting its surface or, when using expanded graphite, by molding using a mold. However, in recent years, an attempt has been made to use a metal plate such as stainless steel in place of a conventionally used carbon material. This is because the use of a metal plate is advantageous in that the cost is lower and the thickness is thinner than in the case of using a carbon material, so that the fuel cell can be made compact, and the metal plate is less likely to crack and is resistant to vibration.

[0009]

When a metal plate is used as a separator, a combination of a pressed metal plate and an elastic material is aimed at achieving both a gas flow path and a sealing function from the viewpoint of cost reduction and the like. A scheme has been proposed. However, if an attempt is made to provide a sufficient sealing function to the elastic material, there is a problem that the entrance and exit of the gas flow channel are crushed by the tightening of the laminate, so that the gas distribution is deteriorated and the battery performance is reduced.

On the other hand, if priority is given to securing the gas flow path, the sealing function of the elastic material is reduced. Therefore, after the laminate is tightened, it is necessary to reinforce the sealing function with a curable sealing adhesive or the like. However, in this method, it is necessary to mask the entrance and exit of the gas flow path before the application of the sealing adhesive, and there is a problem that the assembly process of the polymer electrolyte fuel cell is greatly increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hybrid separator made of a metal plate and an elastic material, which has both a sealing function and a gas flow path.

[0012]

According to the present invention, there is provided an electrode / electrolyte membrane assembly comprising a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane, and a gas supplied to the electrode, wherein a product gas and an excess gas are supplied. A conductive plate for a polymer electrolyte fuel cell obtained by laminating conductive separators having gas flow paths for discharging gas, and a metal plate having grooves or ribs for guiding gas on a surface in contact with the electrode. A seal member that forms an entrance and exit of the gas flow path and the gas flow path in cooperation with the groove or the rib, and acts as a gasket that prevents gas from leaking out of the gas flow path to the outside; The present invention relates to a conductive separator, wherein the seal member on the metal plate is made of a plurality of elastic materials having different hardnesses.

[0013] Further, according to the present invention, the sealing member may form a portion that covers the side surface of the metal plate and protrudes from the metal plate, and the protruding portion includes a gas flow path on the metal plate. The present invention relates to a conductive separator in which a groove or a concave portion serving as an extension of an inlet or an outlet is formed up to the end of the protruding portion.

[0014] The present invention also relates to a conductive separator, characterized in that, in the sealing member, a portion of the metal plate that forms the inlet / outlet of the gas flow path is made of an elastic material having the highest hardness.

The present invention also provides a polymer electrolyte fuel cell comprising an electrode electrolyte membrane assembly comprising a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane, and the conductive separator being alternately laminated. About.

Further, according to the present invention, (1) an electrode electrolyte membrane assembly comprising a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane and the conductive separator are alternately laminated to obtain a laminate. (2) a step of applying a sealing adhesive to the entire side surface of the side surface of the obtained laminate where the portion of the conductive separator projecting from the metal plate is exposed, (3) the sealing member After curing of the adhesive, the portion of the conductive separator projecting from the metal plate is cut off in the middle of the extension of the inlet or outlet of the gas flow path or at the boundary between the metal plate and the projecting portion, and (4) a step of installing a manifold so that the manifold communicates with an inlet or an outlet of a gas flow path of a cut surface generated by cutting off the overhanging portion; Battery process for the preparation of.

[0017] In particular, in the sealing member, a portion forming an entrance and an exit of the gas flow path on the metal plate and a protruding portion are made of an elastic material having the highest hardness. The present invention relates to a method of manufacturing a fuel cell.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A conductive separator for a polymer electrolyte fuel cell according to the present invention comprises a metal plate and a sealing member. The metal plate has a groove or a rib for guiding a gas to a surface in contact with the electrode, and the sealing member supplies the gas to the electrode on the metal plate in cooperation with the groove or the rib. , A gas passage for discharging generated gas and surplus gas, and an entrance and exit of the gas passage. And
The sealing member also functions as a gasket that prevents gas from leaking out of the gas flow path to the outside. The seal member has a plurality of portions made of elastic materials having different hardnesses.

From the viewpoint of enhancing the sealing function, the sealing member is generally provided on the entire periphery of the metal plate while forming the entrance and exit of the gas flow path. The passage formed by the seal member forming the entrance and exit of the gas flow path functions as an inlet or an outlet for the gas that communicates the manifold with the separator, and also for the cooling water. Note that, for example, if the seal member is attached to the entire peripheral edge of the metal plate except for a part of the pair of opposing edges, a part of the pair of opposing edges where the seal member is not provided is provided. And a groove communicating between the inside of the peripheral portion on the metal plate and the outside of the metal plate surface, and finally, this becomes the entrance.

The metal plate is preferably made of stainless steel, aluminum, carbon steel or the like.
A 0.5 mm one is used. As a method of forming a groove or a rib for guiding gas in the metal plate, for example, press working is simple.

Preferably, the metal plate is coated with a conductive material. Further, as the conductive material, conductive oxides such as tin oxide, TiN, Ti-A
Conductive nitrides such as 1N and conductive carbides such as n-type SiC are preferable. The thickness of the coating is generally on the order of 100 ° (angstrom) to 1 μm.

The seal member needs to be made of a plurality of elastic materials having different hardnesses. Specifically, the hardness difference is 10 to 40, more preferably 20 to 40, particularly 30 to 4
It is preferable that the seal member is formed from at least two kinds of elastic materials that are zero. If the hardness difference is less than 10, a problem occurs due to a decrease in the sealing function, or it is difficult to secure the entrance and exit of the gas flow channel due to insufficient hardness, and if it exceeds 40, the higher hardness elastic material becomes brittle. Tend. The higher hardness is 70-8
0 hardness, the lower one is 30-60, even 30
It preferably has a hardness of ４０40. In addition, from the viewpoint of achieving both the sealing function and the securing of the gas flow path, the seal member of the portion forming the entrance and exit of the gas flow path on the metal plate is formed of a plurality of elastic materials having different hardnesses. It is preferable to use an elastic material having the highest hardness.

The hardness of the seal member is determined by the hardness test method for vulcanized rubber and thermoplastic rubber (JIS-K-625).
Required in 3).

The thickness of the sealing member on the metal plate is preferably 0.3 mm or more from the viewpoint of achieving both a sealing function and securing a gas flow path. This is because if the seal member is too thin, it becomes difficult to secure the gas flow path.

The sealing member is preferably formed at a predetermined position on the metal plate by injection molding, in view of simplicity of the process and suitability for mass production. Further, as the elastic material constituting the seal member, a material having a certain degree of rubber elasticity after injection molding can be used without particular limitation. Above all, from the viewpoint of enhancing the sealing function of the sealing member, an elastomer material having high water resistance is preferable. In view of the above, as injection molding materials suitable for use in the present invention, styrene-based elastomers such as styrene-butadiene rubber, fluororubber, nitrile-based elastomer, glass-reinforced polyester-based elastomer, and olefin-based elastomer as main components And the like.

Before assembling the fuel cell by laminating the separator with the MEA, the seal may be formed from the viewpoint of improving the reliability of the fuel cell, reducing the number of parts and the cell assembling process, and reducing the cost during mass production. It is preferable that the cover is made of a member and has a portion that covers the side surface of the metal plate corresponding to the inlet or the outlet of the gas flow path and protrudes from the metal plate. And it is preferable that a groove or a concave portion which becomes an extension of an inlet and an outlet of the gas flow path on the metal plate is formed in the protruding portion up to the end of the protruding portion. Hereinafter, such a separator is referred to as a “separator having an extended gas inlet / outlet and a closed end”. In addition, the gas doorway is extended,
In addition, the separator having the closed end can be easily obtained by injection-molding an injection-molding material at a predetermined position on a metal plate using a mold.

When the gas inlet / outlet is extended and the separator whose end is closed and the MEA are alternately laminated, the side surface of the laminated body where the portion where the sealing member protrudes is exposed is sealed. State. On the side,
This is because the ends of the extended portions of the inlet and the outlet of the gas flow path in the closed state are exposed. Therefore, when it is necessary to apply a sealing adhesive to the entire side surface to reinforce the sealing function, labor such as masking is not required. When a gap (for example, in the vicinity of the periphery of the gas diffusion layer constituting the MEA) is formed in the laminate, the sealing adhesive is impregnated only into the gap, and a gap is formed between the gas inlet and outlet formed in the separator. Intrusion can be prevented.

A sealing adhesive is applied to the entire side surface of the sealing member where the overhanging portion is exposed, and after the sealing adhesive is cured, the overhanging portion is connected to the inlet and outlet of the gas flow path. When the cutting is performed in the middle of the extension portion or at the boundary between the metal plate and the protruding portion, holes communicating with the inlet and the outlet of the gas passage of the separator are exposed on each cut surface. If the manifold is installed so that the hole communicates with the manifold hole, it is possible to further secure the sealing function and the gas flow path.

[0029]

Next, the present invention will be specifically described based on examples. Example 1 Production of MEA Acetylene black-based carbon powder was added with an average particle size of about 30.
An electrode was formed from a material carrying 25% by weight of platinum particles of Å (angstrom) (hereinafter referred to as catalyst powder). Specifically, a dispersion in which the catalyst powder was dispersed in isopropanol and a dispersion in which perfluorocarbon sulfonic acid powder was dispersed in ethyl alcohol were mixed to form a paste. Next, the paste was applied to a thickness of 25
A screen was printed on one side of a 0 μm carbon nonwoven fabric to form a catalytic reaction layer, which was used as an electrode. Platinum amount contained in the resulting electrode, 0.5mg / cm ^2, the amount of perfluorocarbon sulfonic acid was adjusted to 1.2 mg / cm ^2. The electrodes had the same configuration for both the positive electrode and the negative electrode. In addition, as perfluorocarbon sulfonic acid, Nafion manufactured by DuPont
(Trade name) was used.

Next, the obtained pair of electrodes is placed on a proton conductive polymer electrolyte membrane having an area slightly larger than the electrodes, and the catalytic reaction layer on the carbon nonwoven fabric is placed on the center of both sides of the polymer electrolyte membrane. Arranged to touch. And
This was hot-pressed and joined to obtain an MEA. Here, as the proton conductive polymer electrolyte membrane, the perfluorocarbon sulfonic acid (Nafio manufactured by DuPont) was used.
n) having a thickness of 25 μm was used.

Production of Conductive Separator A stainless steel (SUS316) plate 1 having a rectangular shape and a thickness of 0.3 mm as shown in FIG. 1 was used. The central part 10
A corrugated portion having a pitch of about 5.6 mm (groove width of about 2.8 mm) was formed in a region of cm × 9 cm by press working. FIG. 1 is a view assuming a state in which an external manifold 15 is attached to a pair of opposed side portions of the stainless steel plate 1 after laminating the plate-shaped components. That is, FIG.
The state in which the external manifold 15 is provided is shown by expressing only the external manifold 15 in a cross-sectional view perpendicular to the flow direction of the manifold holes 4 and 4 '. FIG. 2 shows a cross section orthogonal to the grooves or ribs of the stainless steel plate 1. A stainless steel plate 1 has a groove 2 with a depth of about 1 mm.
And a rib 3 having a height of about 1 mm.

Next, a 0.5 μm thick tin oxide layer doped with In was formed on the entire surface of the pressed stainless steel plate 1 by vacuum electron beam evaporation. The deposition was performed at a substrate temperature of 300 ° C. in an Ar gas atmosphere with a degree of vacuum of 5 × 10 ⁻⁶ Torr.

Next, the two peripheral edges of the stainless steel plate 1 having different hardnesses are formed so as to have a predetermined structure.
A sealing member made of any kind of fluoro rubber was provided. The formation of the seal member was performed by injection molding.

Hydrogen gas flow path FIG. 3 shows a state in which a seal member made of two kinds of fluororubbers having different hardnesses is provided on the surface of the separator serving as the hydrogen gas flow path.
Shown in Of the two pairs of opposing edges of the stainless steel plate 1, there is a portion where no seal member is provided on one pair of edges on the side that comes into contact with the manifold after the components are stacked. This portion serves as an inlet 6 and an outlet 6 'for connecting the manifold holes 4a and 4a' through which hydrogen flows shown in FIG. 1 to the gas flow path of the separator. And entrance 6
In addition, seal members 5 and 5 ′ made of fluorine rubber having a rubber hardness of 80 are provided around the outlet 6 ′.

The sealing members 5 and 5 'have a thickness of about 1 m.
m, that is, substantially the same as the depth of the groove (the height of the rib) formed in the stainless steel plate 1. Also, curved portions 8 and 8 'as shown in FIG. 3 are formed in the sealing members 5 and 5' so that hydrogen flowing from the inlet 6 sequentially passes through the grooves one by one. The ends of adjacent grooves were connected to each other. A sealing member 7 made of fluorine rubber having a rubber hardness of 60 (hereinafter, the sealing member 7 is referred to as a gasket 7 to be distinguished from the sealing member 5) is formed on the other opposite edge of the stainless steel plate 1.

Air Flow Path FIG. 4 shows a state in which a seal member made of two kinds of fluoro rubbers having different hardness is provided on the surface of the separator which is to be an air flow path. Here, an inlet 6 and an outlet 6 'are formed so as to connect the manifold holes 4b and 4b' through which the air shown in FIG. 1 flows with the gas flow path of the separator, and the ends of six adjacent grooves are connected to each other. The structure was the same as that of the surface serving as the hydrogen gas flow path, except that the curved portions 8 and 8 'were formed in the seal members 5 and 5' having a rubber hardness of 80 so that the rubber gas channels could be connected. What changes the structure between the air side and the hydrogen gas side is
This is because the gas flow rate differs by about 25 times between the air side and the hydrogen gas side. That is, by changing the structure of the gas flow path in accordance with the gas flow rate, it is possible to adjust the gas flow rate and the gas pressure loss to the optimum values.

FIG. 5 shows a state in which a sealing member made of two kinds of fluorine rubbers having different hardnesses is provided on the surface of the separator serving as the cooling water passage. Here, an inlet 6 and an outlet 6 'are formed so as to communicate the manifold holes 4c and 4c' through which the cooling water shown in FIG. 1 flows with the gas flow path of the separator, and the ends of all the grooves are connected. Except for providing the sealing members 5 and 5 'having a rubber hardness of 80 as described above, the structure was the same as that of the surface serving as the hydrogen gas flow path.

Production of Polymer Electrolyte Fuel Cell As shown in FIG. 6, each separator and MEA 12 were laminated. In FIG. 6, for easy understanding of the structure of the laminate,
Hydrogen A, oxygen B and cooling water C flowing through each flow path are conceptually shown. At this time, the separator was arranged so that the hydrogen gas flow path 9 and the air flow path 10 faced each other across the MEA so that an excessive shearing force was not applied to the electrode. Further, a cooling water channel 11 was provided for every two cells.

After 50 cells of the MEA 12 are stacked, a stainless steel end plate and a fastening rod are interposed via a current collecting plate and an insulating plate.
The laminate was fastened at a pressure of 0 kgf / cm ² , and the external manifold 15 was installed on the inlet side and the outlet side of the flow path for gas and the like of the laminate, respectively, to complete a polymer electrolyte fuel cell. If the fastening pressure is too small, gas leaks or the contact resistance increases, resulting in a decrease in battery performance.If the fastening pressure is too large, the electrode may be damaged or the separator may be deformed. It is important to change the fastening pressure.

Evaluation of Polymer Electrolyte Fuel Cell The obtained polymer electrolyte fuel cell was maintained at 85 ° C., and hydrogen gas heated and humidified so as to have a dew point of 83 ° C. on one electrode side was added to the other. Humidified and heated air was supplied to the electrode side of the sample so as to have a dew point of 78 ° C. As a result, a battery open-circuit voltage of 50 V was obtained when there was no load in which no current was output to the outside. 80% fuel utilization and 40% oxygen utilization for this cell
The output characteristics under the condition of a current density of 0.5 A / cm ² were examined.

Comparative Example 1 A battery similar to that of Example 1 was manufactured except that the seal members 5 and 5 'and the gasket 7 were both formed of fluororubber having a rubber hardness of 60, and evaluated in the same manner as in Example 1. did.

Comparative Example 2 A battery was manufactured in the same manner as in Example 1 except that both the sealing members 5 and 5 'and the gasket 7 were formed of fluorine rubber having a rubber hardness of 80, and evaluated in the same manner as in Example 1. did.

Evaluation Results The output characteristics of each of the batteries of Example 1 and Comparative Examples 1 and 2 were evaluated 100 each. As a result, the battery of Comparative Example 1 had a voltage variation width of about 100 mV, while the battery of Example 1 had a voltage variation width of about 50 mV.
Met. In the battery of Comparative Example 2, the performance of the obtained battery was low because the fluororubber of the separator was easily brittle and it was difficult to stably manufacture the fuel cell.
Variation was also the largest.

Example 2 A styrene-based elastomer having a rubber hardness of 80 (S
BR) and sealing members 5 and 5 ′ having a rubber hardness of 6
A battery having the same structure as in Example 1 was manufactured except that a sealing member (gasket) 7 made of a styrene-based elastomer having a rubber hardness of 60 was formed instead of the fluororubber of 0, and evaluated similarly.

Comparative Example 3 A styrene-based elastomer (SBR) having a rubber hardness of 60 was used instead of fluoro rubber having a rubber hardness of 60 instead of the seal members 5 and 5 'and the gasket 7.
A battery having the same structure as that of Comparative Example 1 was manufactured except that the battery was formed as described above, and evaluated in the same manner as in Example 1.

Comparative Example 4 A styrene-based elastomer (SBR) having a rubber hardness of 80 was used in place of the fluoro rubber having a rubber hardness of 80 instead of the seal members 5 and 5 ′ and the gasket 7.
A battery having the same structure as that of Comparative Example 2 was manufactured except that the battery was formed as described in Comparative Example 2, and evaluated in the same manner as in Example 1.

Evaluation Results The output characteristics of each of the batteries of Example 2 and Comparative Examples 3 and 4 were evaluated for 100 batteries. As a result, the same tendency as in the case where the batteries of Example 1 and Comparative Examples 1 and 2 were compared was observed. That is, the battery of Comparative Example 3 had a large variation in performance, but the battery of Example 2 had a small variation in performance. In the battery of Comparative Example 4, the styrene-based elastomer of the separator was apt to be brittle, and it was difficult to stably manufacture the fuel cell. In each of the above Examples and Comparative Examples, an external manifold type fuel cell was manufactured. However, it is considered that a similar tendency can be seen in an internal manifold type fuel cell.

Example 3 Manufacture of Conductive Separator In Examples 1 and 2, a separator was manufactured in which the inlet 6 and the outlet 6 ′ were in communication with the manifold holes 4 and 4 ′. As described above, a separator having an extended gas port and a closed end, that is, a separator having an extended inlet 6 and an outlet 6 ′ and a closed end was manufactured.

7 to 9 are views of a part of the structure viewed from above toward the separator surface. FIG. 7 shows a hydrogen gas flow path, FIG. 8 shows an air flow path, and FIG. 9 shows a cooling water flow path,
A state is shown in which a sealing member made of two types of fluororubbers 5 and 7 having different hardnesses is provided. Portions 14 and 1 projecting from a pair of edges of stainless steel plate 1
Reference numeral 4 'covers the side surface of the stainless steel plate 1 and forms extensions 13 and 13' of the inlet 6 and the outlet 6 'for gas and the like. In addition, each figure of FIGS. 7-9 has shown only the side which has the extended part 13 of the inlet 6 of gas etc. among the said pair of edge parts. In addition, in order to easily understand the state in which the seal member is formed, FIG.
2 shows only the seal member.

The thickness of the seal member 5 provided on the stainless steel plate 1 is about 1 mm, and the thickness of the portion 14 where the seal member protrudes is the thickness of the seal member 5 provided on both sides of the stainless steel plate 1. The sum of the thickness and the thickness of the stainless steel plate 1 is obtained. The part 14 and the seal member 5 where the seal member protrudes are made of fluoro rubber having a rubber hardness of 80, and the other pair of edges have a rubber hardness of 60.
1 mm thick sealing member (gasket) 7 made of fluoro rubber. These seal members are provided by injection molding the same material as the injection molding material used in Example 1.

Production of Polymer Electrolyte Fuel Cell The separator and the same MEA used in Example 1 were laminated in the same number and in the same order as the cells of Example 1. That is, the separator was arranged so that the hydrogen gas flow path and the air flow path faced each other across the MEA, and an excessive shearing force was not applied to the electrode. Further, a cooling water channel was provided for every two cells. Then, after stacking 50 cells of MEA, the stacked body was fastened to the stainless steel end plate via a current collector plate and an insulating plate with a fastening rod at a pressure of 20 kgf / cm ² .

Thereafter, a liquid sealing adhesive is applied to the entire side surface of the laminated body where the portions 14 and 14 ′ where the sealing members protrude are exposed. The small gap generated in the above was impregnated with the sealing adhesive. At that time, the carbon nonwoven fabric was impregnated with an adhesive to a depth of about 5 mm from the wall surface. Note that a general isobutylene-based adhesive was used as the sealing adhesive.

After the sealing adhesive was cured, the portions 14 and 14 ′ protruding from the stainless steel plate 1 were cut off at the interface with the stainless steel plate 1. Subsequently, a predetermined manifold is installed on the cut surface by a predetermined method, and an inlet 6 and an outlet 6 ′ for a gas or the like formed in the manifold hole and the separator.
And a polymer electrolyte fuel cell was completed.

The obtained battery was evaluated in the same manner as in Example 1. As a result, good performance almost equivalent to that of the battery of Example 1 was obtained.

[0055]

According to the present invention, in a hybrid separator composed of a metal plate and an elastic material, it is possible to achieve both a sealing function and securing a gas flow path.
As a result, it is possible to improve the reliability of the polymer electrolyte fuel cell, reduce the number of parts and the number of assembling steps, and significantly reduce the cost during mass production.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which an external manifold shown in a cross section is installed on a stainless steel plate formed by pressing a corrugated portion used in Example 1 of the present invention.

FIG. 2 is a view showing a cut surface orthogonal to a groove or a rib of a stainless steel plate formed by pressing a corrugated portion used in Example 1 of the present invention.

FIG. 3 is a view showing a state in which a sealing member made of two kinds of fluororubbers having different hardness is provided on a surface serving as a hydrogen gas flow path of the conductive separator used in Example 1 of the present invention.

FIG. 4 is a view showing a state in which a sealing member made of two kinds of fluorine rubbers having different hardness is provided on a surface serving as an air passage of the conductive separator used in the first embodiment of the present invention.

FIG. 5 is a diagram showing a state in which a sealing member made of two kinds of fluororubbers having different hardness is provided on a surface serving as a cooling water flow path of the conductive separator used in the first embodiment of the present invention.

FIG. 6 is a conceptual diagram showing the internal structure of the fuel cell stack according to the first embodiment of the present invention.

FIG. 7 is a view partially showing a state in which a sealing member made of two kinds of fluorine rubbers having different hardness is provided on a surface serving as a hydrogen gas flow path of a conductive separator used in Embodiment 3 of the present invention.

FIG. 8 is a view partially showing a state in which a sealing member made of two kinds of fluorine rubbers having different hardness is provided on a surface serving as an air flow path of a conductive separator used in Embodiment 3 of the present invention.

FIG. 9 is a view partially showing a state in which a sealing member made of two types of fluororubbers having different hardness is provided on a surface serving as a cooling water flow path of a conductive separator used in Example 3 of the present invention.

FIG. 10 is a view partially showing only a seal member made of two kinds of fluororubbers having different hardness provided on a surface serving as a cooling water flow path of a conductive separator used in Embodiment 3 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stainless steel plate 2 Groove 3 Rib 4, 4 'Manifold hole 5, 5' Seal member 6 Inlet of gas etc. 6 'Outlet of gas etc. 7 Seal member (gasket) 8, 8' Curved part 9 Hydrogen gas flow path 10 Air flow Road 11 Cooling water flow path 12 MEA 13 Extension 14 Overhang 15 External manifold A Hydrogen B Oxygen C Cooling water

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhito Hato 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5H026 AA06 BB04 BB06 CC03 CC08 CX04 CX08 EE02 EE19 HH00

Claims (6)

[Claims] An electrode-electrolyte membrane assembly comprising a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane, and a gas flow path for supplying gas to the electrodes and discharging generated gas and excess gas A conductive plate for a polymer electrolyte fuel cell obtained by laminating conductive separators having: a metal plate having a groove or rib for guiding gas on a surface in contact with the electrode; and cooperating with the groove or rib. And a seal member that forms an entrance and exit of the gas flow path and the gas flow path, and serves as a gasket that prevents gas from leaking out of the gas flow path to the outside. , Made of a plurality of elastic materials having different hardnesses. 2. The sealing member forms a portion that covers the metal plate side surface and protrudes from the metal plate, and the protruding portion includes an inlet or an outlet of a gas flow path on the metal plate. The conductive separator according to claim 1, wherein a groove or a recess serving as an extension portion is formed up to an end portion of the overhanging portion. 3. The conductive separator according to claim 1, wherein, in the sealing member, a portion of the metal plate that forms the inlet / outlet of the gas flow path is made of an elastic material having the highest hardness. . 4. An electrode electrolyte membrane assembly comprising a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane, and the conductive separator according to any one of claims 1 to 3 alternately laminated. Polymer electrolyte fuel cell. 5. A laminated body is obtained by alternately laminating an electrode electrolyte membrane assembly comprising a polymer electrolyte membrane and a pair of electrodes sandwiching the polymer electrolyte membrane and the conductive separator according to claim 2. (2) a step of applying a sealing adhesive to the entire side surface of the side surface of the obtained laminate where the portion of the conductive separator projecting from the metal plate is exposed, (3) the sealing member After curing of the adhesive, the portion of the conductive separator projecting from the metal plate is cut off in the middle of the extension of the inlet or outlet of the gas flow path or at the boundary between the metal plate and the projecting portion, and (4) A polymer electrolyte fuel cell, comprising a step of installing a manifold so that the manifold communicates with an inlet or an outlet of a gas flow path of a cut surface generated by cutting off a protruding portion. Manufacturing method. 6. The sealing member according to claim 5, wherein a portion forming an entrance and an exit of the gas flow passage on the metal plate and a protruding portion are made of an elastic material having the highest hardness. A method for producing a molecular electrolyte fuel cell.