JP2001266913A - Separator for fuel cell and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a fuel cell superior in electrical properties and mechanical stabilities and its easy manufacturing method. SOLUTION: In the separator for the fuel cell in which the separator has multiple protruding portions (3) that are abutting on a surface of an electrode and electrically conductive, and the multiple protruding portions (3) are formed by electro-conductive materials which are joined on a surface of electro- conductive circuit board (2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator which is arranged between cells constituting a fuel cell stack to perform a current collecting function and form a fuel gas passage and an oxidizing gas passage. And a method of manufacturing the same.

[0002]

2. Description of the Related Art For example, a solid electrolyte type fuel cell comprises a unit cell (single cell) provided with electrodes on both sides of a thin-film electrolyte, and a fuel cell stack is formed by laminating a large number of such single cells. Then, power is taken out at the required voltage and current. In that case, electricity is taken out by conducting to each electrode, and a fuel gas (for example, hydrogen gas) or an oxidizing gas (for example, air) is applied to the surface of the electrolyte through each electrode.
In order to supply a reaction gas such as the above, a separator is arranged on the surface side of the electrode, that is, between each single cell.

[0003] Therefore, the separator is made of a conductive material for extracting electric power, and is configured to be in conductive contact with the electrode and to form a flow path for flowing a reaction gas between the separator and the surface of the electrode. It is necessary to have. In order to satisfy such demands, a separator having a gas flow path formed by forming a large number of concave and convex portions on a conductive plate material such as a metal, contacting the convex portions with the electrodes, and connecting the concave portions to each other is used. Have been tried.

In a fuel cell, an electromotive force is obtained by an electrochemical reaction between a fuel gas and an oxidizing gas via an electrolyte. Therefore, an oxidation reaction occurs on the cathode side, and a reduction reaction occurs on the anode side. Occurs. Since the separator is installed in such a reducing atmosphere and an oxidizing atmosphere,
High corrosion resistance is required, and at the same time electrical conductivity is required as high as possible. Furthermore, since the electric power obtained by the unit cells is small, it is necessary to form a stack by integrating tens or hundreds of unit cells in order to be put to practical use, and the required number of separators increases. It is required to have a structure that can be manufactured as inexpensively as possible.

Under such technical background, a separator in which a large number of projections are formed on a surface of a metal substrate with a synthetic resin and a metal thin film is formed on the surface has been disclosed in Japanese Unexamined Patent Publication No.
No. 12246 proposes this. Specifically, in the separator described in this publication, a protrusion is injection-molded on a surface of a metal base such as aluminum using a polymer having excellent fluidity, and a metal thin film is further coated on the entire surface by surface coating. It is a formed separator.

[0006]

In the case of the above-described separator, the projections that come into contact with the electrodes can be formed by injection molding a synthetic resin on the surface of the metal substrate. It is not necessary to carry out metal working, and the productivity is improved, and there is a possibility that an inexpensive separator can be obtained. However, since the projections are in contact with the electrodes to form an electric path, and at the same time, a gas flow path is provided between the projections.
It is preferable that the thickness is as small as about several mm, and it is desirable that the film be formed at a high density. Further, when the protrusions are formed of a synthetic resin, a metal thin film is formed as described above to secure conductivity, so that the metal thin film is
It is desirable to contact the metal substrate between the projections and to ensure conductivity for the metal substrate for each projection. Therefore, each of the above-described projections is formed in large numbers with a small interval therebetween. Thousands to tens of thousands of such minute synthetic resin projections are securely attached to the surface of the metal substrate. It is technically difficult to form it, and a stable separator that can be put to practical use has not yet been produced.

Further, in the separator described in the above publication, conduction between the projection and the metal substrate is performed by a metal thin film. However, in view of manufacturability and cost, the metal thin film is formed of a metal thin film. As thin as possible, it is desirable that the conductivity of the metal thin film is reduced, the electrical resistance of the entire separator is increased, and the power generation efficiency of the fuel cell may be reduced. In addition, the metal thin film and the metal substrate come into contact with each other between the projections, but the space allowed for the contact is extremely limited. Electrical characteristics could be reduced.

The present invention has been made in view of the technical problem described above, and has as its object to provide a fuel cell separator having excellent electrical characteristics and a method for easily manufacturing the separator. It is.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for forming a large number of minute projections by bonding or adhering or depositing a conductive material on the surface of a conductive substrate. It is characterized by having been formed.
More specifically, the invention according to claim 1 relates to a fuel cell separator having a large number of protrusions which are brought into contact with the surface of an electrode and are electrically connected to each other. And a large number of the protrusions are formed.

Therefore, according to the first aspect of the present invention, since the protruding portion forming the electric path from the electrode to the substrate is formed of a conductive material, the conductivity of this portion is improved.
In addition, the projection and the substrate can be securely and stably joined. Further, a flow path or a water flow path for the fuel gas or the oxidizing gas can be secured between the projections. As a result, it is possible to obtain a separator having excellent fluidity such as gas and water in addition to electrical characteristics.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the substrate is formed of a conductive metal, and the conductive material is a conductive metal of the same or different type as the substrate. Is a separator.

Therefore, according to the second aspect of the present invention, the protruding portion and the substrate can be more reliably and stably joined, and the protruding portion can be formed by a coating method such as plating, so that the productivity is good. become.

A third aspect of the present invention is the separator according to the first or second aspect, wherein a corrosion-resistant layer is formed between the projections.

Therefore, according to the third aspect of the present invention, since the portions other than the projections are shielded from the oxidizing atmosphere or the reducing atmosphere by the corrosion-resistant layer, the durability of the separator is improved without impairing the conductivity.

According to a fourth aspect of the present invention, in addition to any one of the first to third aspects, the projection and the surface portion exposed on the projection side have higher corrosion resistance than the conductive substrate and the projection. A separator characterized by being coated with a conductive metal.

Therefore, according to the invention of claim 4, the corrosion resistance of the entire surface of the separator is improved without lowering the conductivity.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a fuel cell separator having a large number of protrusions which are brought into contact with the surface of an electrode and are electrically conductive, wherein a masking member having a large number of through holes is electrically conductive. Placed on the surface of the substrate, in that state, by performing a coating process with a conductive material, bonded to the substrate through the through-hole and projecting to the surface side of the masking member and rising from the surface of the masking member The method is characterized in that protrusions are formed and the masking member is exposed in a portion between the protrusions.

Therefore, according to the fifth aspect of the present invention, a separator having a structure in which a large number of conductive protrusions protrude from a flat plate-shaped so-called base portion can be manufactured, and a method such as plating can be employed as a coating method. The separator can be easily manufactured.

A sixth aspect of the present invention is the method according to the fifth aspect, wherein the masking member is made of a corrosion-resistant material.

Therefore, according to the invention of claim 6, it is possible to manufacture a separator having a structure in which a large number of conductive protrusions protrude from a flat plate-shaped so-called base portion, and at the same time, a portion between the protrusions can be subjected to corrosion-resistant coating. A separator having excellent properties and durability can be manufactured.

According to a seventh aspect of the present invention, in addition to the configuration of the first aspect, the protrusion is formed of a sintered body.

According to the seventh aspect of the present invention, in addition to the same effect as that of the first aspect of the present invention, since a gap is formed between the particles constituting the sintered body, gas enters the gap. As a result, the reaction area between the gas and the electrode is increased as much as possible, and the diffusion region of the gas with respect to the electrode is increased, but the contact area between the electrode and the projection is not reduced.

According to an eighth aspect of the present invention, in addition to the configuration of the seventh aspect, at least one surface of the substrate or the protrusion is covered with a conductive metal having higher corrosion resistance than the substrate or the protrusion. It is characterized by the following.

According to the eighth aspect of the present invention, in addition to the same effect as that of the seventh aspect of the present invention, even if at least one surface of the substrate or the projection is exposed to a reducing atmosphere or an oxidizing atmosphere, the surface of the substrate or the projection is exposed Corrosion is suppressed.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be specifically described with reference to the drawings. FIG. 1 shows a separator 1 according to the present invention.
The separator 1 shown here has a structure in which a large number of conductive protrusions 3 are provided on at least one surface of a conductive substrate 2. The separator 1 is disposed between the cells (not shown) in the fuel cell stack, and is electrically connected to the electrode 4 by bringing each protrusion 3 into contact with the electrode 4 to serve as a current collector. While functioning, the space formed between each protrusion 3
The flow path 5 is configured to flow a fuel gas such as hydrogen, an oxidizing gas such as air, or a liquid such as water.

The conductive substrate 2 has a function of maintaining airtightness and watertightness, having a strength to maintain a flat shape, and having a function of guiding a current to the outside from between the unit cells. It is formed of a metal plate such as stainless steel or aluminum, a conductive ceramic plate, a thin plate obtained by applying a conductive coating to the ceramic plate, a carbon molded body, a conductive sheet material, a conductive resin, or the like. In addition,
The separator 1 may be disposed on the cathode side or the anode side of the fuel cell. The separator 1 may be disposed on any of the electrode sides. Is a strong oxidizing atmosphere, so that a material having excellent oxidation resistance is preferably used as the material of the substrate 2.

The protrusion 3 has a very small outer dimension and height of about 1 mm or about several mm.
It is provided at intervals of about mm or several mm. The shape and arrangement pattern are shown in FIG. The example shown in FIG. 2A is an example in which the protrusions 3 are formed in a columnar shape and arranged in a matrix. The example shown in (B) is an example in which the projections 3 are formed in a prismatic shape and arranged in a matrix. Further, the example shown in (C) is an example in which the protrusions 3 are formed in an elliptical cross section, are arranged in a staggered manner, and the direction of the oval is reversed in each row.

The material forming the projections 3 is only required to have conductivity, and the same material as the substrate 2 or a different conductive material can be used. If the same type of material is used, the bonding strength between the projection 3 and the substrate 2 is increased. Also, if the projection 3 is formed of the same type of material as the substrate 2 even if the types are different, the projection 3 and the substrate 2 Increases the bonding strength. The projection 3 forms an electric path between the electrode 4 and the substrate 2 and therefore preferably has high conductivity. In addition, since the projection 3 comes into direct contact with the electrode 4, it has oxidation resistance. Therefore, it is preferable that the protruding portion 3 is formed of a relatively hardly oxidizable metal such as nickel (Ni) or tin (Sn).

As described above, the space formed between the projections 3 becomes the flow path 5 for flowing gas or water, and this part is directly exposed to an oxidizing atmosphere or a reducing atmosphere. You. Therefore, a corrosion-resistant layer 6 such as a corrosion-resistant film is formed between the projections 3. The corrosion-resistant layer 6 is formed of a synthetic resin such as acrylic, epoxy, polypropylene, vinyl chloride, and polyethylene; a ceramic such as silicon oxide, zirconia, and alumina; and a metal such as gold, platinum, silver, tungsten, titanium, and chromium. Can be. Among them, a material having electrical insulation is particularly preferable. When such a corrosion-resistant layer 6 is provided, the substrate 2 may have a structure in which the electrical characteristics are more important than the corrosion resistance, whereas the protrusion 3 may have a structure in which the electrical characteristics and the corrosion resistance are more important. And the degree of freedom in material selection and design is improved.

As described above, since the protrusion 3 is brought into direct contact with the electrode 4 and is directly exposed to an oxidizing atmosphere or a reducing atmosphere, corrosion resistance is required in addition to conductivity. For this purpose, in the above example, an example is shown in which an oxidation-resistant metal such as nickel or tin is used, but a corrosion-resistant coating may be provided instead or in addition to this. FIG. 3 schematically shows an example, in which a corrosion-resistant coating 7 is formed on the entire outer surface of the projection 3 and the entire surface of the corrosion-resistant layer 6. The corrosion-resistant coating 7 is required to have higher corrosion resistance than the material forming the protrusions 3 and needs to have conductivity, and therefore is made of a noble metal such as gold (Au) or silver (Ag). When this type of corrosion resistant coating 7 is provided, the above-described corrosion resistant layer 6 can be omitted.

Next, the separator 1 according to the present invention will be described.
A method of manufacturing the device will be described. As described above, the basic structure of the separator 1 according to the present invention is such that the conductive substrate 2
Is formed by bonding a large number of conductive protrusions 3 to at least one surface of the substrate 2. Therefore, as a material of the substrate 2, a plate material 10 which is not subjected to special processing such as drilling or bending is prepared. (FIG. 4A). That is, the above-mentioned metal plate, ceramic plate, carbon molded body, or conductive sheet is used. On at least one surface of the material plate 10, a conductive material such as nickel or tin is joined in a number of points to form the projections 3 (FIG. 4B).

As a method for forming the projections 3, for example, as shown in FIG. 5, the material plate 10 is sandwiched between a molding die 11 and the cavity 1 corresponding to the shape of the projections 3 is formed.
By forming the conductive material 13 into the cavity 12 and pressurizing and injecting the conductive material 13 into the cavity 12, it is possible to adopt a method in which the conductive material 13 is formed into a protruding shape and, at the same time, bonded to the material plate 10.

Another method for forming the projections 3 is a plating method. That is, as shown in FIG. 6, a masking sheet 15 provided with a large number of through holes 14 in the shape and position corresponding to the projections 3 is joined to the surface of the material plate 10 for the substrate 2 (see FIG. )). As the masking sheet 15, an insulating material is used in order to prevent a conductive material from adhering during plating described below.

With the material plate 10 and the masking sheet 15 set in this way, they are placed in a plating apparatus and plated with a conductive material such as nickel or tin. Since only the portion of the material plate 10 that is exposed to the plating solution corresponds to the through-hole 14, a conductive material is electrodeposited on the portion and gradually deposited, and finally the masking sheet 15
Is raised in a nugget shape on the surface side of the substrate, and a projection 3 is formed (FIG. 6B).

When the corrosion-resistant coating 7 shown in FIG. 3 is formed on the surface of the separator 1 manufactured by the method described with reference to FIGS. 4 to 6, the ion plating, sputtering, or CVD method is used. (Chemical vapor deposition method), PVD method (physical vapor deposition method) or the like may be used to form the corrosion-resistant material into a thin film.

The separator 1 according to the present invention described above or the separator 1 manufactured by the method of the present invention is disposed between unit cells and stacked together with the unit cells to constitute a fuel cell stack, similarly to the conventional separator. . Fig. 7 shows an example.
FIG. 1 schematically shows a single cell. That is, a hydrogen electrode 21 serving as a cathode and an oxygen electrode 22 serving as an anode are formed on both sides of the electrolyte membrane 20, the separator 1 is disposed on the surface side thereof, and the projection 3 is formed on each of the electrodes 21, 21.
2 is contacted. In this state, the space between the projections 3 forms a flow path for gas and water.

In this case, the respective projections 3 of the separator 1 come into contact with the electrodes 21 and 22 of the cell to be electrically connected, and electric power can be taken out to the external load 23. In the separator 1 according to the present invention, since the projections 3 are formed of a conductive material, the entirety of the projections 3 constitutes an electric path, and thus the distance between the electrode and the substrate 2 or the terminal (not shown). The conductivity is increased and the overall resistance value of the separator 1 is reduced, resulting in the separator 1 having excellent electrical characteristics. In addition, since each of the protrusions 3 can be formed by bonding a molten metal to the substrate 2 by a method such as welding or plating, the bonding strength between the protrusions 3 and the substrate 2 is high. The separator 1 having high mechanical strength and high durability in that point can be obtained. Also,
When the corrosion-resistant layer 6 is provided between the projections 3 or when the corrosion-resistant coating 7 is formed on the entire surface, corrosion in an oxidizing atmosphere is prevented or suppressed.
Durability is improved.

In the method according to the present invention described above, fine and many projections 3 can be formed without performing mechanical processing such as punching, bending, and coining on the substrate 2. As a result, the fuel cell separator can be easily and inexpensively manufactured.

The present invention only needs to have a structure in which a large number of conductive projections are formed on a conductive substrate. Therefore, as shown in FIG. The coating 3a may be applied to form a projection 3 integrally with the coating 3a, and a corrosion-resistant layer 6 may be provided between the projections 3 and on the surface of the coating 3a.

When the projections 3 are formed by plating, a masking sheet 15a having the structure shown in FIG. 9 may be used. That is, the masking sheet 15a shown in FIG. 9 has a cylindrical portion 14a formed integrally with the periphery of the through-hole 14. By performing plating using the masking sheet 15a, the conductive material is formed. The protrusions 3 are formed by being gradually deposited inside the cylindrical portion 14a. As a result, the cylindrical portion 14a wraps around the formed projection 3 and the masking sheet 1
Since the material forming 5a is insulative and exhibits electrical corrosion resistance during power generation by the fuel cell, the corrosion resistance of the side surfaces of the projections 3 is improved, and the durability of the separator 1 is improved. .

The factors that improve the power generation efficiency of the fuel cell include the fact that the reaction area between the gas such as oxygen and hydrogen and the electrode or the diffusion region of the gas to the electrode is expanded as much as possible. In order to enhance the current collection effect by promoting the transfer of electrons to the electrode, there is a matter that the contact area between the electrode and the projection is increased as much as possible. However, when the electrode and the projection are in contact with each other, the reaction surface between the gas and the electrode and the contact surface between the electrode and the projection are arranged adjacent to each other, and the gas diffusion region is Is formed inside the electrode corresponding to the contact surface between the electrode and the protrusion. For this reason, conventionally, it has been difficult to achieve both of the above two items (in other words, contradictory characteristics).

Therefore, an example of the structure of the separator 1 for solving such a problem will be described with reference to FIGS. FIG. 10 is a cross-sectional view schematically showing the separator 1, and the entirety of the protrusion 3 is formed of a sintered body obtained by sintering a large number of conductive particles 24. In a state where the conductive particles 24 are in contact with each other, and
A plurality of stages are arranged between the substrate 2 and the electrodes 4. Examples of the sintered body constituting the protrusion 3 include carbon, metal,
A conductive resin, a conductive ceramic, and the like can be given. Further, the particle size of each conductive particle 24 is from φ0.01 mm to φ0.01 mm.
It is set in the range of 2.0 mm. Further, in FIG. 10, the particle diameters of the conductive particles 24 are all set to be the same. In FIG. 10, the corrosion layer 6 of FIG. 1 is omitted for convenience.

In the specific example of FIG. 10, the projections 3 are formed of a sintered body obtained by sintering a large number of conductive particles 24, and a gap is formed between the conductive particles 24. Each conductive particle 24 is provided on the tip end surface of each protrusion 3.
Thereby forming fine irregularities. Therefore, the flow path 5
As a gas such as oxygen or hydrogen existing in the gas enters the gap, a reaction area between the gas and the electrode 4 is increased as much as possible, and a diffusion region of the gas with respect to the electrode 4 is expanded. In this manner, even if the reaction area between the gas and the electrode 4 is increased as much as possible and the diffusion region of the gas with respect to the electrode 4 is increased, the contact area between the electrode 4 and the projection 3 is reduced. In this case, the contact area between the electrode 4 and the protrusion 3 can be increased as much as possible, and the electrical resistance at the contact surface between the electrode 4 and the protrusion 3 decreases. In other words, the above two items can be compatible, and the power generation efficiency of the fuel cell is improved.

Further, since the projections 3 are made of a sintered body, even if the shapes of the projections 3 are complicated, they can be easily formed. That is, FIG.
According to the specific example of No. 0, it is not necessary to finely process the surface of the protrusion 3 which is in contact with the electrode 4 by machining or the like, so that the material constituting the protrusion 3 is wasted and the processing time is reduced. Prolonged time is suppressed, and an increase in the manufacturing cost of the separator 1 can be suppressed. Furthermore, since the protrusions 3 are formed of a sintered body, the above-described various conductive materials can be used as the sintered bodies forming the protrusions 3, and the degree of freedom in selecting the material is increased. In particular, ceramics that are difficult to process can be used as the protrusions 3.

FIG. 11 is a cross-sectional view schematically showing the separator 1 in which the projections 3 have a large number of conductive particles 24 and 25.
Is constituted by a sintered body obtained by sintering That is, the protruding portion 3 is constituted by a large number of conductive particles 24 arranged in contact with the substrate 1 and a large number of conductive particles 25 arranged in contact with the electrode 4. ing. The particle size of the large number of conductive particles 24 arranged in contact with the substrate 1 is set to be larger than the particle size of the large number of conductive particles 25 arranged on the side in contact with the electrode 4. . In the specific example of FIG. 11, the same operation and effect as those of the specific example of FIG. 10 can be obtained.

FIG. 12 is a cross-sectional view schematically showing the separator 1, in which the protrusions 3 are formed of a sintered body obtained by sintering a large number of conductive particles 26. Here, the particle size of many conductive particles 26 is set to two or more types, and conductive particles 26 having different particle sizes are arranged irregularly. Further, a flat surface 27 polished is formed on the surface of the protrusion 3 opposite to the substrate 2. The flat surface 27 comes into contact with the electrode 4. In the specific example of FIG. 12, the same operation and effect as those of the specific example of FIG. 10 can be obtained.

Next, the projection 3 shown in FIGS.
Will be described with reference to FIG. FIG.
3 is a plan view of the substrate 2, that is, a view of the substrate 2 as viewed from the electrode 4 side. The example shown in FIG.
Are formed in a prismatic shape, and the respective protrusions 3 are arranged in a matrix with each other. The example shown in FIG. 13B is an example in which each protruding portion 3 is formed in a band shape along the plane direction of the substrate 2 and each protruding portion 3 is arranged in a plurality of rows along the width direction thereof. The example shown in FIG.
This is an example in which the projections 3 are arranged in a bent shape in a crank shape. The example shown in FIG. 13D is an example in which each of the protrusions 3 is formed in a substantially elliptical shape, and a plurality of each of the protrusions 3 are arranged in the major axis direction and the minor axis direction.

Further, in the separator 1 shown in FIGS. 10 to 12, a conductive metal having higher corrosion resistance than the substrate 2 and the projection 3 is coated on at least a part of at least one of the substrate 2 and the projection 3. It can also be coated. Here, the “front surface” means a surface facing the electrode 4. For example, the protrusion 3 shown in FIG. 3 can be made of the conductive particles shown in any of FIGS. When the separator 1 without the corrosion-resistant layer 6 is formed, the corrosion-resistant coating 7 can be formed on the entire surface of the projection 3 and the surface of the substrate 2. Further, although not shown, a corrosion-resistant coating may be formed only on the surface of the substrate 2 for the separator 1 shown in FIGS.

Further, in the separator 1 of the specific example shown in FIGS. 10 to 12, a corrosion resistant film can be formed only on the entire surface of the projection 3. Further, in the separator 1 shown in FIGS. 10 to 12, a corrosion-resistant coating can be formed only on the protruding portions 3 which are in contact with the electrodes 4. As described above, when the corrosion-resistant coating 7 of FIG. 3 is applied to at least a part of the surface of the substrate 2 or the projection 3 with respect to the specific examples of FIGS. Even if a part is exposed to an oxidizing atmosphere or a reducing atmosphere, its corrosion is suppressed and the durability of the separator 1 is improved.

Note that the same effects as those of the specific example of FIG. 1 can be obtained in the specific examples of FIGS. In addition, in the specific examples of FIGS. 10 to 13, the same components as those of the specific examples of FIGS. 1 to 9 are denoted by the same reference numerals as those used in FIGS. 1 to 9, and description thereof is omitted. I have. Here, the correspondence between the configuration of each specific example and the configuration of the present invention will be described. The corrosion resistant layer 6 corresponds to the corrosion resistant layer of the present invention, and the corrosion resistant coating 7 corresponds to the conductive metal of the present invention. .

[0051]

As described above, according to the first aspect of the present invention, the projections forming the electric path from the electrodes to the substrate are formed of a conductive material, and the projections are joined to the conductive substrate. Therefore, the protrusions and the flow path formed by the protrusions are stable, and the cross-sectional area of the electric path from the electrode to the substrate is increased, and the conductivity is improved.
It is possible to obtain a separator excellent in electric characteristics and flowability of fluid such as gas.

According to the second aspect of the present invention, since the projection is formed of a conductive metal, the projection and the substrate can be more securely and stably joined to each other. Since the projections can be formed by the coating method described above, the productivity is improved.

Further, according to the third aspect of the present invention, since the portions other than the protrusions are shielded from the oxidizing atmosphere or the reducing atmosphere by the corrosion-resistant layer, the durability of the separator is improved without impairing the conductivity. be able to.

According to the fourth aspect of the present invention, the projection and the surface exposed on the projection side are covered with the conductive substrate and the conductive metal having higher corrosion resistance than the projection. The corrosion resistance of the entire surface of the separator can be improved without lowering.

According to the fifth aspect, it is possible to manufacture a separator having a structure in which a large number of conductive projections protrude from a flat plate-shaped so-called base portion, and it is possible to employ a method such as plating as a coating method. Can be easily manufactured.

According to the sixth aspect of the present invention, a separator having a structure in which a large number of conductive protrusions protrude from a flat plate-shaped so-called base portion can be manufactured, and at the same time, a portion between the protrusions is covered with a corrosion-resistant coating. As a result, a separator excellent in conductivity and durability can be easily and inexpensively manufactured.

According to the seventh aspect of the present invention, in addition to obtaining the same effect as the first aspect of the present invention, since the gas enters the gap between the particles constituting the sintered body, the reaction area between the gas and the electrode is reduced. As much as possible, the diffusion area of the gas with respect to the electrode is enlarged, and the contact area between the electrode and the projection is not reduced. Therefore, the power generation efficiency of the fuel cell is improved.

According to the invention of claim 8, in addition to obtaining the same effect as the invention of claim 7, even if at least one surface of the substrate or the projection is exposed to a reducing atmosphere or an oxidizing atmosphere, Surface corrosion is suppressed. Therefore,
The corrosion resistance of the separator is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of a separator according to the present invention.

FIG. 2 is a diagram showing a shape and an arrangement pattern of the protrusions.

FIG. 3 is a cross-sectional view schematically showing an example of the present invention in which a corrosion-resistant coating is applied to the entire surface.

FIG. 4 is a diagram schematically showing a manufacturing process according to the method of the present invention.

FIG. 5 is a schematic view for explaining another example of the manufacturing method according to the present invention.

FIG. 6 is a schematic view for explaining still another example of the manufacturing method according to the present invention.

FIG. 7 is a diagram schematically showing the structure of a fuel cell, that is, an example of use of a separator.

FIG. 8 is a cross-sectional view schematically showing another example of the separator according to the present invention.

FIG. 9 is a partial sectional view schematically showing another masking sheet that can be used in the plating method according to the present invention.

FIG. 10 is a cross-sectional view schematically showing another example of the separator according to the present invention.

FIG. 11 is a cross-sectional view schematically showing another example of the separator according to the present invention.

FIG. 12 is a cross-sectional view schematically showing another example of the separator according to the present invention.

FIG. 13 is a plan view of a projection of FIGS. 10 to 12,
FIG. 4 is a diagram showing a planar arrangement pattern.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Separator, 2 ... Substrate, 3 ... Projection part, 4, 2
1,22 ... electrode, 6 ... corrosion resistant layer, 7 ... corrosion resistant coating,
14 ... through-hole, 15, 15a ... masking sheet.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiaki Matsumoto 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 5H026 AA06 BB04 CC04 CX04 EE02 HH03

Claims (8)

[Claims] 1. A fuel cell separator having a large number of protrusions which are brought into contact with the surface of an electrode and are electrically conductive, wherein the plurality of protrusions are formed by a conductive material bonded to a surface of a conductive substrate. A fuel cell separator, comprising: 2. The fuel cell separator according to claim 1, wherein the substrate is formed of a conductive metal, and the conductive material is the same or different conductive metal as the substrate. 3. The fuel cell separator according to claim 1, wherein a corrosion-resistant layer is formed between the protrusions. 4. The projection according to claim 1, wherein the projection and the surface exposed on the projection side are covered with a conductive metal having higher corrosion resistance than the conductive substrate and the projection. The fuel cell separator according to any one of the above. 5. A method of manufacturing a fuel cell separator having a large number of projections which are brought into contact with the surface of an electrode and are electrically conductive, wherein a masking member having a large number of through holes is arranged on the surface of the conductive substrate. Then, in this state, by performing a coating treatment with a conductive material, the protrusion is formed on the surface side of the masking member while being joined to the substrate through the through hole and protruding from the surface of the masking member. A method for manufacturing a fuel cell separator, comprising exposing the masking member at a portion between the projections. 6. The method according to claim 5, wherein the masking member is made of a corrosion-resistant material. 7. The fuel cell separator according to claim 1, wherein the protrusion is formed of a sintered body. 8. The fuel cell according to claim 7, wherein at least one surface of the substrate or the projection is covered with a conductive metal having higher corrosion resistance than the substrate or the projection. For separator.