JPH0477421B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrode support member for a phosphoric acid fuel cell and a method for manufacturing the same.

More specifically, the present invention comprises a separator, a porous carbonaceous rib part and an end seal part that are joined to the separator to form a plurality of grooves serving as reaction gas hole channels, and the rib part and the end seal part are orthogonal to each other. A fuel cell member formed by joining both sides of a separator so as to face each other, the rib part and the separator being joined by a fluororesin dispersion, and the rib part of the separator being joined. The present invention relates to a fuel cell member and a method of manufacturing the same, characterized in that an end seal portion is joined to each end parallel to the rib portion of the surface via a fluororesin layer.

[Background of the Invention] In recent years, fuel cells have attracted attention as a clean energy generation device, or as a power generation device that can be opened and closed, which can contribute to resource conservation by leveling the operation of thermal or hydroelectric power generation, improving energy efficiency, etc. There is a high demand for the development and use of fuel cells and their peripheral systems.

In particular, with the recent commercialization and mass production of fuel cells, there are increasing demands not only for fuel cell performance, but also for compact cell dimensions, reductions in manufacturing costs, and the like.

[Prior art] Conventionally, a phosphoric acid fuel cell uses a separator in which reactive gas holes are formed by mechanically processing grooves in an impermeable thin plate made of dense graphite, and carbon fiber is placed on top of the separator as an electrode substrate. It is known that a phosphoric acid matrix is placed through paper. However, in a fuel cell having such a structure, the cost of machining grooves in the separator is high, and furthermore, since the separator rib portion is made of a dense carbon material, phosphoric acid cannot be stored therein.

Recently, a structure in which ribs made of a similar carbon material are bonded to a separator made of a dense carbon material has been proposed, but such a structure not only does not solve the above-mentioned problem of phosphoric acid accumulation, but also Depending on the conditions, a new problem arises in that there remains concern about the gas sealing properties at the ends.

[Object of the Invention] The present invention provides a fuel cell member, which is a separator having an end seal portion and a rib portion, which can be manufactured extremely easily and at low cost without complex groove machining of a carbon thin plate. The purpose is to

Another object of the present invention is to provide a fuel cell member with extremely reliable end gas sealing properties.

Another object of the present invention is to provide a fuel cell member capable of storing phosphoric acid in rib portions forming reaction gas holes.

A further object of the present invention is to provide a method for manufacturing the above fuel cell member.

Further objects and advantages of the present invention will be apparent to those skilled in the art from the following description.

[Structure of the Invention] The present invention comprises a separator, a porous carbonaceous rib portion and an end seal portion that are joined to the separator to form a plurality of grooves serving as reaction gas hole paths, and the rib portion and the end seal portion are A fuel cell member formed by joining both sides of a separator so as to face each other perpendicularly, the rib part and the separator being joined by a fluororesin dispersion, and the rib part of the separator A fuel cell member is provided, characterized in that an end seal portion is joined to each end parallel to the rib portion of the joined surface via a fluororesin layer.

Furthermore, the present invention applies a fluororesin dispersion to the ends of both sides of the separator material except for the end sealing member joints, and after drying, a plurality of porous carbonaceous rib members are placed at predetermined positions on the separator material. is 1
The rib members are joined by the fluorine resin dispersion so that the two separator faces are parallel to each other, and the rib members are orthogonal to each other on both sides of the separator, and the separator material to which the rib members are joined is The present invention also provides a method for manufacturing the fuel cell member, which comprises joining an end seal member made of a gas-impermeable dense carbon material to each end parallel to the rib member of the surface via a fluororesin sheet. .

Hereinafter, the fuel cell member of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a fuel cell member of the present invention. The figures are exaggerated and do not represent the actual size. Appropriate dimensions for each member, particularly regarding thickness, will be apparent to those skilled in the art.

The fuel cell member of the present invention includes a separator 1
It has a structure consisting of a plurality of rib portions 2 which together with the separator form grooves serving as reaction gas hole paths, and end seal portions 3 at each end of the separator in a direction parallel to the rib portions.

The lengths of the rib portion 2 and the end seal portion 3 are equal to the side length of the separator 1. As shown in the figure, the rib portions 2 are joined to both sides of the separator 1 at a desired interval so as to face each other perpendicularly, and end seals are applied to both ends of the separator parallel to the rib portions 2 on each side. The two parts are joined so that their outer ends coincide. The separator 1 and the rib portion 2 are joined by a fluororesin dispersion, and the separator and the end seal portion 3 are connected to a fluororesin sheet 4.
are connected via.

FIG. 2 is a partial cross-sectional view at - of the fuel cell member of the present invention in FIG. 1.

The rib portion shown in the figure has a rectangular cross-section;
Although it extends linearly parallel to the sealed end, it may have any shape as long as the reaction gas hole path formed can sufficiently supply the reaction gas. It can also be made non-linear, and in this case it is possible to measure the distribution of stress applied to the member, which is particularly advantageous during manufacturing. Furthermore, it is also possible to make the rib part discontinuous so that the reaction gas hole path is communicated internally, and a member having a joint surface with the separator of any shape such as a circle, ellipse, or rectangle can be connected in series with the separator. , may be arranged in parallel, or may be joined arbitrarily. The cross-sectional view of the reactant gas pores formed when a fuel cell is formed does not need to be the same on both sides of the separator, and may be changed depending on the conditions of the reactant gas to be supplied. Of course, combinations of these are also possible.

However, from the viewpoint of providing a fuel cell member that can be manufactured through an easy process, which is one of the objects of the present invention, the shape of the rib portion is naturally a columnar shape with a rectangular cross section as shown in the figure. It is most advantageous to do so. In such a rib portion having a rectangular cross section, the size can be set as desired for the fuel cell to be formed, but the height may be 0.4 to
The width is preferably 1.5 mm and the width is preferably 1.0 to 3.3 mm, and the bonding interval is preferably 1 to 3 mm.

The rib portion is made of porous carbonaceous material and has an average bulk density of 0.4 to 0.8 g/cc gas permeability of 200 ml/cm ²・hr・mmAq or more and electrical resistance of 100 mΩ・cm or less after firing at 800°C or higher. It is preferable that at least 80% or more of the pores are open pores.

The porous carbonaceous rib member of the fuel cell member of the present invention is formed by heating and press-molding a mixture of short carbon fibers, a binder, and organic particulate matter (for example, JP-A-59-68170 and JP-A-58-117649). (see issue),
In particular, a mixture consisting of 20 to 60 wt% short carbon fibers with a length of 2 mm or less, 20 to 50 wt% of phenolic resin, and 20 to 50 wt% of organic particulate matter (pore control material) is molded at a molding temperature of 100 to 180°C and a molding pressure of 2 to 100 Kgf. /cm ² G and a pressure holding time of 1 to 60 minutes, and baked at 800° C. or higher.

The carbon material precursor mixture as described above may be once formed into a flat plate shape, fired, and then cut to obtain a rib member of a desired size.

The separator has an average bulk density of 1.4 g/cc or more, a gas permeability of 10 ^-7 ml/cm ²・hr・mmAq or less, and an electrical resistance.
10mΩ・cm or less, preferably 2mm or less in thickness, 2000
It is more preferable that the material is fired at a temperature of 0.degree. C. or higher.

The separator material used in the present invention is 2000
A dense carbon plate having a firing shrinkage rate of 0.2% or less when fired at °C is preferable.

Further, the end seal portion is preferably made of a dense carbon material having an average bulk density of 1.4 g/cc or more and a gas permeability of 10 ⁻⁴ ml/cm ² ·hr·mmAq or less.

In the present invention, the porous carbonaceous rib member and the separator material are joined by a fluororesin dispersion. Fluorine resins that can be used include:
For example, tetrafluoroethylene resin (PTFE, melting point
327℃, 4.6Kgf/cm ² G heat distortion temperature 121℃), tetrafluoroethylene-hexafluoropropylene copolymer resin (abbreviation FEP, melting point 250-280℃, 4.6Kgf/cm ² G heat distortion temperature 72℃) , fluorinated alkoxyethylene resin (abbreviated as PFA, melting point 300-310°C, 4.6 Kgf/cm ² G heat distortion temperature 75°C), and fluorinated ethylene propylene resin (abbreviated as TFP, melting point 290-300°C). These fluororesins are commercially available.

The fluororesin dispersion is used as a dispersion containing 10 to 70% by weight, for example, about 60% by weight of the above-mentioned fluororesin. Small amounts of surfactants can be added to the dispersion.

After applying the above fluororesin dispersion to the edges of both sides of the separator material, excluding the areas where the end sealing members are joined, at a coating amount of 3 to 7 mg/cm ² , the joint surfaces of each rib member are coated. Match, 10-60
Fusion bonding is performed at a pressure of Kgf/cm ² G or higher, a temperature of about 300 to 430°C, and a press time of 1 to 60 minutes.

Incidentally, although the above-mentioned fluororesin is a non-conductive substance, the conductivity between the porous carbonaceous rib portion and the separator is sufficiently ensured by the above bonding conditions. This is because the fluororesin applied to the separator is thermally deformed and impregnated into the porous carbon rib member during the pressure bonding process in the above joining process, so both members are bonded with sufficient strength. This is thought to be because sufficient contact between the two members is ensured at the same time as they are joined.

The fluororesin used for joining the end seal member and the separator material in the present invention is not particularly limited, but
For example, the fluororesin used for joining the separator material and the rib member described above can be used, and these are used in the form of a sheet having a thickness of, for example, about 100 μm.

The separator material and the end seal member are joined by sandwiching the above fluororesin sheet between the end seal member joining surface of the separator material and the end seal member surface to be joined to the separator material, and applying a pressure of 1 Kgf/cm ² G. This is carried out by fusion bonding at a pressure above and a temperature above (melting point -50°C) of the resin.

The above-mentioned porous carbonaceous rib member and separator material, and the above-mentioned end seal member and separator material can be joined simultaneously or separately if conditions are appropriately selected.

In the fuel cell member of the present invention, the amount of leakage to the outside through the end seals including the joints is dominated by diffusion and is not affected much by pressure. The amount of leak gas per unit time per peripheral length is preferably 10 ⁻² ml/cm ² ·hr·mmAq or less when expressed by the relationship: [leak gas amount/(side length)·(differential pressure)].

[Effects of the Invention] The fuel cell member of the present invention can be manufactured by simply cutting raw materials for each component having the desired physical properties that have been molded and fired in advance, and then joining them by heating and pressing in a mold. There is no need to make complicated grooves on the separator made of dense carbon material, and it can be manufactured at a much lower cost than conventional members made by forming grooves on dense carbon plates.

Furthermore, since the end seal portion of the fuel cell member of the present invention is integrally bonded with fluororesin,
Excellent gas leak resistance at the edges.

Further, since a porous carbon material is used for the rib portion, phosphoric acid can be stored on the wall surface forming reaction gas pores of the formed fuel cell, and the reaction gas can be diffused.

Furthermore, since the rib portion and the separator, as well as the end seal portion and the separator are integrally bonded with fluororesin, it has excellent phosphoric acid resistance.

[Examples] The present invention will be described below with reference to Examples, but the present invention is not limited to the following Examples.

A fuel cell member was manufactured using the following materials.

Rib member Porous carbonaceous flat plate material pre-fired at 800℃ or higher (manufactured by Kureha Chemical Industry Co., Ltd., product name “KES-”)
400”, bulk density 0.58g/cc, gas permeability 550ml/
cm ²・hr・mmAq, electrical resistance 30mΩ・cm, thickness 1.2
mm) was cut with a 0.1 mm thick diamond blade to a width of 2 mm and a length of 300 mm.

Separator material Showa Denko Co., Ltd. dense carbon plate (product name “SG-2”)
Bulk density 1.55g/cc, gas permeability 10 ^-9 ml/cm ² .
hr・mmAq or less, electrical resistance 4.5 mΩ・cm or less, thickness 0.6 mm) was cut into 300 mm lengthwise and widthwise pieces to make separator material.

End sealing member: Dense carbon plate manufactured by Tokai Carbon Co., Ltd. (product name “Toka Separator”), bulk density 1.85 g/cc, gas permeability 10 ^-7 ml/cm ²・hr・mmAq or less, thickness 1.1
mm) was cut into 300 mm length x 15 mm width pieces to make four pieces and used as end sealing members.

Fluoropolymer dispersion PTFE dispersion containing 60% by weight of PTFE in water (Mitsui Dupont Fluorochemical Co., Ltd.)
(trade name “J-30”) was used.

Four fluororesin sheets (manufactured by Nichias Co., Ltd., product name "TOMBO900", thickness 0.1 mm) were cut to match the vertical and horizontal dimensions of the end sealing member.

Apply 5 mg/cm ² of PTFE dispersion to the parts of both sides of the separator material where the end sealing members are not bonded.
The coating amount was applied and dried. A predetermined number of rib members, a separator material, and a predetermined number of rib members are supplied into a predetermined mold in this order at a temperature of 380℃ and a pressure of 20Kgf/cm ²
G: Fusion bonding was performed by holding the pressure for 20 minutes.

Next, on the end surface parallel to the ribs of the separator.
An end seal member was placed through a PTFE sheet so that the outer ends of each member were aligned, and fusion bonded under the same conditions as above to obtain a member with a thickness of 3.0 mm.

After the obtained member was immersed in a 95% by weight phosphoric acid solution for 1 hour, the dripping liquid was cut off and the weight was measured, and the weight increase was 41%. On the other hand, dense carbon material (manufactured by Tokai Carbon Co., Ltd., bulk density
1.85g/cc, product name Toka Separator, thickness
A member having the same dimensions as the above member was made by cutting a groove in the material (3.0 mm), and was similarly immersed in a phosphoric acid solution.The weight increase was 6%. Thus, it can be seen that the amount of phosphoric acid supported by the member of the present invention is extremely superior to that of a member whose rib portion is made of a dense carbon material.

We also measured the electrical resistance of the obtained parts.
It was 35 mΩ・cm ² . On the other hand, when we stacked the rib member and separator material in the same way as the above members and measured the electrical resistance in the same way without joining them with a PTFE dispersion, it was 60 mΩ・cm ² , and it was found that the electrical resistance was 60 mΩ・cm 2. It was also found that the contact resistance between the rib portion and the separator could be reduced by this.

[Brief explanation of the drawing]

The attached FIG. 1 is a perspective view of the fuel cell member of the present invention, and FIG. 2 is a partial sectional view of the fuel cell member of the present invention. DESCRIPTION OF SYMBOLS 1... Separator, 2... Rib part, 3... End seal part, 4... Fluorine resin.

Claims (1)

[Claims] 1. A separator comprising a porous carbonaceous rib portion and an end seal portion that are joined to the separator to form a plurality of grooves serving as reaction gas hole paths, and the rib portion and the end seal portion are orthogonal to each other. a fuel cell member formed by joining both sides of a separator so as to face each other, the rib portion and the separator being joined by a fluororesin dispersion;
and a fuel cell member, characterized in that an end seal part is joined to each end parallel to the rib part of the surface of the separator to which the rib part is joined, via a fluororesin layer. 2 The porous carbonaceous rib portion has a bulk density of 0.4 to 0.8 g/cc, a gas permeability of 200 ml/cm ²・hr・mmAq or more,
The fuel cell member according to claim 1, which is a porous carbon material having an electrical resistance of 100 mΩ·cm or less. 3 The separator has a bulk density of 1.4 g/cc or more,
Gas permeability below 10 ^-7 ml/cm ²・hr・mmAq, 10m
The fuel cell member according to claim 1 or 2, which is a dense carbon material having an electrical resistance of Ω·cm or less and a thickness of 2 mm or less. 4. Claim 1, characterized in that the end seal portion is a dense carbon material having a bulk density of 1.4 g/cc or more and a gas permeability of 10 ^-4 ml/cm ² ·hr · mmAq or less - The fuel cell member according to any one of Item 3. 5. The fuel cell member according to any one of claims 1 to 4, wherein at least 80% or more of the pores of the porous carbon material of the porous carbonaceous rib portion are open pores. . 6 Apply fluororesin dispersion to the edges of both sides of the separator material except for the joints of the end sealing members, and after drying, a plurality of porous carbonaceous rib members are placed at predetermined positions on the separator material to form one separator. The rib members are joined by the fluororesin dispersion so that the rib members are parallel to each other on both sides of the separator, and the rib members are orthogonal to each other on both sides of the separator. A method for manufacturing a fuel cell member, which comprises joining an end seal member made of a gas-impermeable dense carbon material to each end parallel to a rib member via a fluororesin sheet. 7 The porous carbonaceous rib member is made of 20 to 60% by weight of short carbon fibers with a length of 2 mm or less and 20 to 50% by weight of binder.
7. The method according to claim 6, characterized in that the method is produced by firing a molded member obtained by integrally heating and press-molding a mixture consisting of 20 to 50% by weight of an organic particulate material. 8 The separator material has a bulk density of 1.4 g/cc or more,
Gas permeability below 10 ^-7 ml/cm ²・hr・mmAq, 10m
The method according to claim 6 or 7, characterized in that the plate is a dense carbon plate having an electrical resistance of Ω·cm or less and a thickness of 2 mm or less. 9. Claim 6, characterized in that the end sealing member is a dense carbon material having a bulk density of 1.4 g/cc or more and a gas permeability of 10 ^-4 ml/cm ² ·hr · mmAq or less ~The method according to any one of paragraphs 8 to 8. 10 The porous carbonaceous rib member has a bulk density of 0.4 to 0.8 g/cc, a gas permeability of 200 ml/ ^cm2・hr・mmAq or more, and an electrical resistance of 100 mΩ・cm or less The method according to any one of the ranges 6 to 9. 11 The joining conditions between the rib member and the separator using fluororesin dispersion are a temperature of 300℃ to 430℃.
11. The method according to any one of claims 6 to 10, characterized in that the temperature is 10 to 60 Kgf/cm ² G or higher, and the pressing time is 1 to 60 minutes. 12 The bonding conditions between the end seal member and the separator material through the fluororesin are a pressure of 1 Kgf/cm ² G
12. The method according to any one of claims 6 to 11, wherein the temperature is at least (melting point -50°C) of the fluororesin. 13 At least of the pores of the porous carbonaceous rib member
13. The method according to claim 6, wherein 80% or more of the pores are open pores. 14. The method according to any one of claims 6 to 13, characterized in that the porous carbonaceous rib member and the end seal member are joined to the separator material simultaneously or separately.