JPS6119070A - Separator which also serves as inter cooler for fuel cell and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a separator which prevents flow out of reaction gas and serves as an inter cooler by bonding together a gas separating part and a gas leakage prevention edge, and installing holes for cooling fluid nearly in the center in a direction of thickness of the gas separating part. CONSTITUTION:A separator 10 comprises a gas separating part 11 and a gas leakage prevention edge 12 bonded together by burning. A plurality of holes 13 for cooling fluid are installed neary in the center of a direction of thickness of the gas separating part 11. The holes 13 are formed in parallel to the surface and the side of the electrode substrate, and passed through one side to the other side. Thereby, reaction gasses are separated each other, and leakage of gasses to the side is prevented, and moreover the separator also serves as an inter cooler.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a fuel cell separator and a method for manufacturing the same, and more particularly, the present invention relates to a separator for fuel cells and a method for manufacturing the same, and more particularly, it has improved characteristics and is useful as a separator for fuel cells that also serves as an intercooler. separator and its manufacturing method.

(Prior Art) Conventionally, a bipolar separator type fuel cell using a bipolar separator obtained by ribbing an impermeable graphite thin plate is known.

On the other hand, one side is provided with ribs, and the other side is
Monopolar electrode substrates have been developed that have a structure with a flat electrode surface, in which a reactive gas diffuses from a ribbed surface to a flat electrode surface.

A conventional monopolar fuel cell has an electrode substrate, a catalyst layer, a rib structure on one side and a flat structure on the other side.
It consists of a laminated matrix and separator sheet impregnated with an electrolyte, and the reactive gas (oxygen or hydrogen) diffuses from the electrode substrate's grooved surface to the flat electrode surface.

Various types of separators have been proposed for use in fuel cells.

When these separators are stacked together with a porous substrate as a gas diffusion part, positive and negative electrodes, and a phosphoric acid matrix to form a fuel cell, they isolate each reaction gas from each other and at the same time function as connecting conductors between unit cells. ing. Therefore, fuel cell separators have low gas permeation.
It is required to have characteristics such as low thermal and electrical resistance, and especially when the battery area is large, mechanical strength such as high bending strength is required.

However, in a conventional monopolar fuel cell, a porous electrode substrate and a separator as a gas diffusion part are used. (When layering, the electrical and thermal contact resistance between the electrode substrate and the separator becomes unreasonably large. Generally, such contact resistance is several times the transfer resistance within the substrate.) It is said that this can lead to a decrease in power generation efficiency due to unsuitable temperature distribution between cells.

The present inventors disclosed in Japanese Patent Application Laid-Open No. 59-68170 that a porous carbonaceous layer as a gas diffusion layer is provided on both sides of a dense carbonaceous layer that functions as a separator, and is integrated. Provided an electrode substrate for fuel cells. In this electrode substrate, the above-mentioned contact resistance was completely eliminated, and thermal and electrical conductivity were greatly improved.

-〇- On the other hand, in fuel cells, for example, the reaction gas also diffuses to the side surfaces of the porous substrate, so in order to prevent this, the ends of the substrate are usually impregnated with a fluorine-based resin, and/or Alternatively, use a peripheral seal member.

In recent years, separators that also serve as this peripheral sealing member have been developed.

For example, in Japanese Patent Application Laid-Open No. 58-214277, reaction gas supply grooves are formed in directions that extend around the entire surface and intersect with each other, and a band-shaped elastic band having several rows of protrusions on both side edges that engage with the supply grooves is disclosed. A gas separator plate for a fuel cell is described in which the sealing surfaces are formed by joining the pieces together. In this gas separation plate (separator), the strip made of, for example, fluororubber or fluororesin molding functions as a gas sealing material, but this strip is not carbonized integrally with the gas separation plate. Therefore, the thermal and electrical resistance of the sealing material portion is large.

Furthermore, Japanese Patent Application Laid-Open No. 58-12267 discloses a fuel cell that is carbonized in one direction (having the same external shape as the above-mentioned gas separation plate with a band-shaped piece for sealing material, but without forming a reaction gas supply groove). gas separation plates are described.

Both gas separation plates are made from a mixture of graphite powder and phenolic resin. For this reason, it was insufficient particularly in terms of gas permeability and mechanical strength (particularly bending strength).

The present inventors also wrote in Japanese Unexamined Patent Publication No. 59-96661,
The present invention provides an electrode substrate for a fuel cell comprising a graphite sheet for peripheral sealing that is integrated with a graphite sheet as a separator to prevent leakage of reaction gas to the side surface of the cell, and a porous carbonaceous layer as a gas diffusion part.

As a result of further research, the present inventors found that, instead of graphite powder as disclosed in the above-mentioned Japanese Patent Application Laid-open No. 58-12267, for example, oxidized pitch calcined and crushed products, carbon fiber cord crushed products, and phenol particle calcined products were used as fillers. When using non-graphitizable carbonaceous particles, preferably fired and crushed oxide pitch products, a peripheral seal part that prevents the reaction gas from leaking to the side of the battery due to carbonization firing, and a separator part that substantially isolates the reaction gas. A separator for fuel cells is obtained, which has excellent mechanical strength such as bending strength, improved gas permeability, and excellent thermal and electrical conductivity. In 1982, he discovered that
A patent application was filed on July 4, 2016.

Further, the cell structure of the fuel cell is such that a cooler is inserted one stage at a time in each of 5 to 8 cells, and all of them are constructed by laminating members. Conventionally, members have been stacked in the order of gas diffusion section, separator, and gas diffusion section, and the problem of electrical and thermal contact resistance between the respective members has been attracting attention.

The problem of contact resistance between unit cells was discussed in Japanese Patent Application Laid-Open No. 59-68.
Although this problem can be solved by using an electrode substrate that integrates a separator and a gas diffusion part as described in Japanese Patent No. 170, the contact resistance between the cell and the intercooler remains unsolved.

Conventional intercoolers are usually made of carbon plates, but there is no known technology to form holes for supplying air or hot water, and the only proposed method is to bond carbon plates with grooves cut on one side. Met. Under these circumstances, the problem of contact resistance between the cell and intercooler remains.

Poling is generally used as a method for forming hollow holes in a carbon plate, but this is not possible for thin plates with lengths ranging from 60 to 8 Ωcm, such as in fuel cells.

(Problem of the Invention) An object of the present invention is to provide a separator for a fuel cell that eliminates the above-mentioned drawbacks. That is, the present invention
To provide an excellent separator which separates reactive gases from each other, prevents leakage of reactive gases to the side surfaces of a battery, and also functions as an intercooler.

(Structure of the Invention) The separator for a fuel cell that also serves as an intercooler of the present invention includes a gas isolation separator portion that isolates the reaction gas of the counter electrode from each other, and a gas leakage prevention edge that prevents the reaction gas from leaking to the side of the cell. The pair of gas leak prevention edges are opposed to each other with a part of the gas isolation separator interposed therebetween, and each pair of the gas leak prevention edges on both surfaces of the gas isolation separator portion are orthogonal to each other. .

In the separator of the present invention, the gas isolation separator portion and the gas leakage prevention edge portion are integrated by carbonization firing, and a group of hollow holes for cooling fluid passages is provided approximately at the center of the thickness of the gas isolation separator portion. It is provided.

The method of manufacturing a separator for a fuel cell that also serves as an intercooler of the present invention involves placing a fired and crushed oxide pitch product in a mold of a predetermined shape, carbon! l Separator raw material mixture consisting of 50 to 90% by weight of carbon filler selected from non-graphitizable carbonaceous particles such as coarsely crushed products and fired phenol particles, and 10 to 50% by weight of binder, hollow for cooling fluid flow path The pore forming material and the separator Kawahara FI mixture are sequentially supplied and preformed to produce a molded plate for a part of the gas isolation lever; separately, the separator raw material mixture is supplied to a mold of a predetermined shape and preformed. These molded plates are stacked and fed into a mold having a predetermined shape so as to have a predetermined structure, and then press-molded, and then 1000
It consists of baking hot water melon at a temperature above ℃.

In addition, another method for producing a separator for a natural battery that also serves as an intercooler according to the present invention is to place the separator raw material mixture, a hollow hole forming material for a cooling fluid flow path, into a mold having a predetermined shape.
The separator raw material mixture is sequentially supplied, press-molded, and then fired at a temperature of 1000° C. or higher.

(Explanation of Preferred Embodiments) The present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these preferred embodiments.

FIG. 1 schematically shows a separator for a fuel cell that also serves as an intercooler according to the present invention.

The fuel cell separator 10 of the present invention includes a gas isolation separator portion 11 that functions to mutually isolate reaction gases of opposite electrodes, and a gas leakage prevention edge portion 12 that functions to prevent the reaction gas from leaking toward the side of the cell. It consists of.

As shown in FIG. 1, a pair of gas leakage prevention edges 12 are provided at opposing peripheral parts with the gas isolation separator section 11 in between, and one pair each on the front and back surfaces of the gas isolation separator section 11. The gas leakage prevention edges 12 are provided so as to be orthogonal to each other. The fuel cell separator 10 of the present invention is entirely carbonized and fired into one piece. That is,
The gas isolation separator section 11 and the gas leakage prevention edge 12 are integrated.

Gas isolation separator section 11 of separator 10 of the present invention
has a plurality of hollow holes 1 as channels for flowing cooling fluid (e.g. air or hot water) approximately in the center of its thickness.
A hollow hole path group consisting of 3 is provided. The hollow holes 13 of this cooling fluid channel group are substantially parallel to each other and to the electrode surface and one side surface of the electrode substrate, and are continuous from one end surface to the opposite end surface of the electrode substrate.

The cross-sectional shape of the hollow hole passage 13 as a flow path for the cooling fluid is the first one.
As shown in the figure, it is circular. The diameter of each hollow hole passage 13 is 1
is preferably 0.5 to 15 IIll, and this diameter is 0.5 to 15 IIll.
If it is smaller than 5+ua, the separator area becomes large and the length of the hollow holes becomes long, and the resistance to the flow of the cooling fluid becomes too large.If it is larger than 15 mm, the gas isolation separator section 11 having the hollow holes becomes too thick. The volumetric efficiency of the cell decreases when the separator is laminated together with the electrode substrate and the like.

The separator 10 of the present invention has excellent airtightness in the entire portion excluding the hollow holes, and the gas permeability in the thickness direction of the separator is 10 ci/sec.

cmHo or less, and has high mechanical strength, for example, bending strength of 500 kQ/cM or more, and has excellent thermal and electrical conductivity, with a thermal conductivity of 4 kcal7
m, hr, 'C or more, electrical resistance is 101IlΩcml
X Lower Te AFr Le.

The height of the gas leakage prevention edge 12 of the separator 10 of the present invention (height from the gas isolation separator part 11) is the porous carbonaceous layer (14 in FIG. 3) as a reaction gas diffusion part.
It corresponds to the thickness of , and is generally 2.5 m+n or less. The gas permeability of the reaction gas toward the side of the battery through this gas leakage prevention edge is a sufficiently low value to prevent the reaction gas from leaking to the side of the battery, and is generally 1.
0-3ci/sec, cml-1g or less.

The separator of the present invention can be manufactured by the method detailed below, but the important thing is that the gas isolation separator section 1
1 and the gas leakage prevention edge 12 are integrally formed by swelling and firing, and have the physical properties as described above.

One preferred method of manufacturing the separators of the invention is to separately preform the molded plates for the gas isolation separator section and the gas leakage prevention edge, and then place them in a mold to the desired configuration. Press molded with
Swells when fired at temperatures above ℃.

First, a method for manufacturing a molded plate for a gas isolation separator section will be explained.

That is, ``a raw material mixture for a separator, a hollow hole passage forming material for a cold fJI fluid flow path, and the raw material mixture for a separator are supplied in this order into a mold having a predetermined shape, and preformed to obtain a molded plate for a gas isolation separator section. .

Here, the separator raw material mixture contains carbon filler 50
~90% by weight, preferably 60-80% by weight and binder 10-50% by weight, preferably 20-40ffl f
Consists of f1%.

The carbon filler used in the implementation of the present invention is selected from non-graphitizable carbonaceous particles such as oxidized bidge calcined crushed products, carbon fiber crushed products, phenol particle calcined products, etc. with an average particle size of 40 μm or less,
Preferably, the particles are 10μ or less, for example,
A material obtained by firing and crushing oxidized bitge produced by vJ by the method described in Japanese Patent No. 3-31116 can be preferably used. Note that the carbon filler may be a mixture of two or more types of non-graphitizable carbonaceous particles described above.

As the binder used in the present invention, phenolic resin is preferred.

The hollow hole forming material for the cooling fluid flow path used in the present invention includes a sag-like molded product of a polymeric material, and examples of the polymeric material include polyethylene, polypropylene, nylon, polystyrene, polyvinyl alcohol, polyvinyl chloride, etc. Therefore, one with a carbonization yield of 10% by weight or less is selected as appropriate.

If the carbonization yield is higher than this, there may be difficulties in forming hollow pores and controlling the equivalent diameter. In addition, these polymeric substances contain at least one
A material that does not volatilize or exhibit melt flow at 00°C is used. That is, the polymeric material is allowed to be thermally deformed on the wet surface and under pressure, but must not volatilize or melt and flow.

A sag-shaped molded product that can be used to adjust the equivalent diameter of the hollow hole to a preferred range can be obtained by injection molding the polymer material in a molten state into a mold, or by injection molding a pellet or powder of the polymer material into a mold. It is made using pressure molding method. The cross-sectional dimensions of each unit sudare are 0 in diameter (Fig. 2 d).
．． 55 to 18.0IIII.

As shown in Figure 2, the interval (T) between the circular unit sudare parallel to the flow direction of the cooling fluid is 3 to 50IllIll, and the interval ('L) between the circular unit sudare in the direction perpendicular to the flow of the cooling fluid. is selected from the range of 30 to 200 fill depending on the purpose. When molding a molded plate for a gas isolation separator part in a mold, these sag-like molded products can be placed on top of the separator raw material mixture so as to be located approximately in the center of the gas isolation separator part, and then After the pressure forming and post-curing steps, most of the material, except for the part that is carbonized by carbonization firing, is evaporated by thermal decomposition to form hollow pores in the separator.

Generally, when forming such hollow pores, it has been confirmed that the molded product during carbonization and firing shows a linear shrinkage rate of 10 to 20% as a whole. By selecting the equivalent diameter, it can be arbitrarily adjusted to obtain a preferred equivalent diameter of the hollow hole channel.

Incidentally, the sag-shaped molded product described in "2" is an example of the hollow pore-forming material of the present invention, and the present invention is not limited thereto. Similarly, polymer materials other than those described above may also be used as long as they have similar characteristics.

The preforming conditions for producing the molded plate for the gas isolation separator section of the present invention are a press temperature IJi of 70 to 130°C.

Preferably 100-120°C, press pressure 30-200
k (1/crJ, preferably 80-150 ko
/cni is 5 to 30 minutes.

Next, the molded plate for the gas leakage prevention edge can be manufactured by supplying the separator raw material mixture to gold 314 of a predetermined shape and preforming it under the same conditions as above.

The thus preformed molded plate is press-formed by placing it in a mold having a predetermined shape that provides a predetermined structure as shown in FIG. 1, for example. Press molding conditions are temperature 120~
200°C, preferably 130-160°C, pressure 30-2
00 k (1/ci, preferably 80-150 k
(J/ctl for 10 to 20 minutes. After press molding, post-curing at a temperature of 130 to 160°C and a pressure of 0.5 kg/CI4 or less for at least 2 hours will give preferable results.

Thereafter, carbonization is performed at a humidity of 1000° C. or higher to obtain an integrated separator of the present invention.

Incidentally, the separator of the present invention can also be integrally molded as follows. That is, the separator raw material mixture, the cooling fluid channel hollow hole forming material, and the separator raw material mixture are sequentially supplied into a mold having a predetermined shape (for example, giving a structure as shown in FIG. 1), It is press-molded under the above conditions, preferably post-cured, and then carbonized and fired at a temperature of 1000° C. or higher.

(Operations and Effects of the Invention) As described above, the fuel cell separator of the present invention has excellent airtightness, that is, low gas permeability, high mechanical strength, such as bending strength, and good thermal and electrical conductivity. It has high thermal conductivity and low electrical resistance, making it particularly suitable as a fuel cell separator.

1 of fuel cell electrode substrate using separator of the present invention
An example is schematically shown in FIG. In FIG. 3, numeral 14 is a porous carbonaceous layer as a reaction gas diffusion section disclosed in, for example, Japanese Unexamined Patent Publication No. 59-96661, and numeral 15 is a hollow hole for a reaction gas flow path. Of course, this is just one example;
The present invention is not limited to this. For example, the substrate or porous carbon disclosed in JP-A-58-117649, JP-A-59-37662, JP-A-59-46763, JP-A-59-63664 and JP-A-59-66063 A material useful as a gas diffusion part, such as a carbonaceous layer, can be used.

Use of the separator of the present invention eliminates the need for sealing means conventionally required to prevent leakage of reactant gas to the side of the cell. Furthermore, since the gas leakage prevention edge is also integrally carbonized and fired, the thermal and electrical resistance is reduced.

Furthermore, since the separator also serves as an intercooler,
The thermal and electrical contact resistance between the conventional vaporizer sheet and intercooler is completely eliminated.

26 - As a result, great effects such as a drastic reduction in electrical resistance and thermal resistance as a whole when laminated are exhibited.

(Example) The invention will now be illustrated by means of non-limiting examples.

Commercially available pellet-shaped polypropylene (manufactured by Tonen Sekiyu Co., Ltd. 1)
Product number J-215) was melted and extruded using a screw injection molding machine at a temperature of 230°C and an injection pressure of 500 ko/crl, and poured into a mold maintained at about 50°C. A sag-shaped polypropylene molded product (hollow hole forming material for cooling fluid flow path) having a shape in which circular unit sudares were connected as shown was made.

The cross section of the molded material shown in Figure 2 is diameter (d).
3.5 In a circle of +n+a, T = 10+ni, l
- = 100+nm grooves were cut into a stainless steel plate, and a stainless steel cover plate was attached so that it could be divided.

Example 2 Oxidized bits (average particle size 10μ or less) produced by the method described in Japanese Patent Publication No. 53-31116 were calcined at 800°C and crushed to have an average particle size of 10μ or less.

A raw material mixture was prepared by mixing 65% by weight of the calcined and crushed oxidized pitch product with 35% by weight of a phenol resin (RM-210, manufactured by Asahi Yokuzai) using a blade mixer.

The obtained raw material mixture was supplied to a press molding die, and then the hollow hole channel forming material for cooling fluid flow path produced in Example 1 (
A roughly #-shaped polypropylene molded product) was supplied. Next, a molded plate for a gas isolation separator portion was obtained by preforming at io°C and 100 kQ/ci.

Separately, the raw material mixture was supplied to a mold of a predetermined shape, and 11
A molded plate for the gas leakage prevention edge was prepared by preforming at 0° C. and 100 kQ/ctl.

The obtained gas leakage prevention edge forming plate was cut to obtain a gas leakage prevention edge veneer having a desired 1 noise.

The above molded plate for the gas isolation separator part and the veneer plate for the gas leakage prevention edge were placed in a mold of a predetermined shape to obtain the desired structure as shown in Fig. 1, and heated at 140°C and 50k (
Press molding was performed at 1/cIl. After that, about 150℃,
It was post-cured at 0.4 kQ/ci and further carbonized and fired at 1500°C.

The physical properties of the obtained separator are shown below.

Gas permeability (at N2. 0.2kO/cd
G) 1.8x 10-? ci/sec, cmH(
+ (excluding the hollow hole) Electrical resistance 7.6 IIIΩ, Cll1 thermal conductivity 4.7 kcal/n+, hr, °C Bending strength 860 k (J/Cd hollow hole diameter 3.11IIIll Gas leakage prevention edge Height 2, Oam Gas permeability to the side (at N2. 0.2kO/
cII! G)5.4x 10=cd/
sec, cmHQ

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the separator of the present invention, FIG. 2 is a schematic diagram of an example of a hollow hole forming material for a cooling fluid flow path used in the present invention, and FIG. 3 is a perspective view of the separator of the present invention. FIG. 2 is a schematic diagram of an electrode substrate when used in a battery.

Claims (17)

[Claims] (1) Consisting of a gas isolation separator section that isolates the reactive gases of the counter electrodes from each other, and a gas leakage prevention edge that prevents the leakage of the reaction gas to the side surface of the battery, the pair of gas leakage prevention edges are connected to the gas leakage prevention edge that They face each other with a gas isolation separator section in between, and each pair of gas leakage prevention edges on both sides of the gas isolation separator section are orthogonal to each other, and carbonization sintering allows the gas isolation separator section and the gas leakage prevention edge to intersect with each other at right angles. A separator for a fuel cell that also serves as an intercooler, in which the gas isolation separator part is integrated with the edge part, and a group of hollow holes for a cooling fluid flow path is provided approximately at the center of the thickness of the gas isolation separator part. (2) Each hollow hole path of the cooling fluid flow channel hollow hole path group is
The electrodes are substantially parallel to each other and to the electrode surface and one side of the electrode substrate, are continuous from one end surface of the electrode substrate to the opposite end surface, and have a diameter of 0.5 to 15 mm. The separator according to scope 1. (3) The portion of the separator excluding the hollow hole group for the cooling fluid flow path is 10^-^7cm^2/sec. cm
Gas permeability below Hg, bending strength above 500kg/cm^2, 4kcal/m. hr. The separator according to claim 1 or 2, which has a thermal conductivity of .degree. C. or more and an electrical resistance of 10 m.OMEGA.cm or less. (4) The gas permeability of the gas leakage prevention edge of the separator in the side direction of the battery is 10^-^3cm^2/se.
c. The separator according to any one of claims 1 to 3, characterized in that the separator has a temperature of not more than cmHg. (5) The separator according to any one of claims 1 to 4, wherein the height of the gas leakage prevention edge is 2.5 mm or less. (6) The separator according to any one of claims 1 to 5, which is fired at a temperature of 1000°C or higher. (7) A method for manufacturing a separator for a fuel cell that also serves as an intercooler according to any one of claims 1 to 6, wherein a mold having a predetermined shape is filled with a fired and crushed oxide pitch product, a crushed carbon fiber product, A raw material mixture for a separator comprising 50 to 90% by weight of a carbon filler selected from non-graphitizable carbonaceous particles such as baked products of phenol particles and 10 to 50% by weight of a binder, a material for forming hollow pores for a cooling fluid flow path, and the separator. The raw material mixture for the separator is sequentially supplied and preformed to produce a molded plate for the gas isolation separator section, and separately, the raw material mixture for the separator is supplied to a mold of a predetermined shape and preformed for the gas leakage prevention edge. Molded plates are manufactured, these molded plates are stacked and supplied to a mold having a predetermined shape so as to have a predetermined structure, press molded, and then 1000
A method consisting of firing at a temperature above ℃. (8) The method according to claim 7, wherein the carbon filler is particles with a particle size of 40 μm or less. (9) The method according to claim 7 or 8, wherein the binder is a phenolic resin. (10) Claims 7 to 9, characterized in that the hollow hole forming material for the cooling fluid flow path is a polymeric substance that does not volatilize or exhibit no melt flow at at least 100°C.
The method described in any of the paragraphs. (11) The polymeric substance is selected from the group consisting of polyethylene, polypropylene, nylon, polystyrene, polyvinyl alcohol, and polyvinyl chloride, and the carbonization yield of the polymeric substance is 10% by weight or less. 11. The method according to claim 10. (12) The method according to claim 10 or 11, wherein the hollow hole forming material for the cooling fluid flow path is a sag-like molded product of the polymeric substance. (13) The sag-like molded product is manufactured by injection molding the polymeric substance in a molten state into a mold, or by pressure-molding pellets or powder of the polymeric substance in a mold. The cross-sectional diameter of the unit sudare is 0.5
13. The method according to claim 12, characterized in that the diameter is 5 to 18.0 mm. (14) A patent claim characterized in that the interval between the unit gaps in the direction parallel to the flow direction of the cooling fluid is 10 to 50 mm, and the interval between the unit gaps in the direction perpendicular to the flow of the cooling fluid is 30 to 150 mm. The method according to item 12 or 13. (15) The preforming conditions are a press temperature of 70 to 130°C;
The method according to any one of claims 7 to 14, characterized in that the press pressure is 30 to 200 kg/cm^2. (16) Press molding conditions are mold heating temperature 120-20
The method according to any one of claims 7 to 15, characterized in that the temperature is 0°C and the molding pressure is 30 to 200 kg/cm^2. (17) A method for manufacturing a separator for a natural battery that also serves as an intercooler according to any one of claims 1 to 6, in which a mold having a predetermined shape is filled with a fired and crushed oxide pitch product and a crushed carbon fiber product. , a raw material mixture for a separator comprising 50 to 90% by weight of a carbon filler selected from non-graphitizable carbonaceous particles such as fired products of phenol particles, and 10 to 50% by weight of a binder; a hollow pore forming material for a cooling fluid flow path; The raw material mixture for the separator is supplied in order, and the temperature is 120.
A method consisting of press forming at ~200°C and a pressure of 30-200 kg/cm^2 and firing at a temperature of 1000°C or higher.