JPH1040937A - Manufacture of collector for fuel cell, and manufacturing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a good quality collector on which separation and a swelling are not caused by performing compression molding without leaving bubbles in a material. SOLUTION: Thermally expansive graphite powder PW being a collector material is set between an upper die 24 and a lower die 26. Afterwards, vacuum pumps 32 and 34 are put in an ON condition, and pressure reduction in a cavity part surrounded by the upper die 24, the lower die 26 and a die 22 is started. Then, an upper silde 28 is moved downward, and a lower slide 30 is moved upward, and pressure is applied to the upper die 24 and the lower die 26, and compression molding is performed on the thermally expansive graphite powder PW. In this way, the compression molding is performed while reducing pressure from the cavity part, and a current collecting body is formed. As a result, the compression molding can be performed without leaving bubbles in the thermally expansive graphite powder PW.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a current collector for a fuel cell, which manufactures a current collector provided in a fuel cell by compression-molding a current collector material.

[0002]

2. Description of the Related Art Conventionally, a fuel cell has been known as a device for directly converting the energy of fuel into electric energy. In a fuel cell, usually, a pair of electrodes are arranged with an electrolyte membrane interposed therebetween, and a surface of one electrode is brought into contact with a fuel gas such as hydrogen, and another surface is contacted with an oxygen-containing gas containing oxygen. Then, electric energy is extracted from between the electrodes by utilizing an electrochemical reaction occurring at this time. The fuel cell can extract electric energy with high efficiency as long as the fuel gas and the oxygen-containing gas are supplied.

[0003] By the way, such a fuel cell is formed by laminating a plurality of joined bodies each composed of an electrolyte membrane and a pair of electrodes.
High output is realized. For this reason, fuel cells are usually
A member called a current collector is disposed at a boundary between the joined bodies, and a plurality of joined bodies are connected in series.

[0004] Such a current collector is manufactured by filling a mold with thermally expandable graphite as a material and applying pressure to the mold (Japanese Patent Laid-Open No. 59-75562). According to this manufacturing method, a current collector having excellent electrical conductivity, corrosion resistance, and thermal conductivity and satisfying gas impermeability is manufactured.

[0005]

By the way, according to the above-mentioned prior art, a high-quality current collector could not be manufactured for the following reasons. That is, since the thermal expansion graphite used as the material of the current collector is a bulky powdery material, bubbles are inevitably generated in the material when the material is filled in the mold. For this reason, the material is subjected to compression molding with the bubbles remaining, and the surface of the manufactured current collector swells or peels off in layers.

The method and apparatus for manufacturing a current collector for a fuel cell according to the present invention have been made in view of these problems, and a high-quality current collector free of peeling or swelling due to the remaining air bubbles has been developed. It is intended to be manufactured.

[0007]

Means for Solving the Problems and Their Functions / Effects As means for solving the above-mentioned problems, the following configuration is adopted.

According to a first aspect of the present invention, there is provided a method for manufacturing a current collector for a fuel cell, comprising filling a current collector material into a molding die and compression-molding the current collector material using the mold. A method of manufacturing a current collector for a fuel cell, which manufactures a current collector for a fuel cell, includes a step of performing compression molding using the mold while reducing the pressure inside the mold.

According to this configuration, compression molding by a mold is performed.
Since the pressure is reduced inside the mold, compression molding can be performed without leaving air bubbles in the current collector material filled in the mold. Therefore, a current collector without peeling or swelling can be manufactured.

According to a second aspect of the present invention, there is provided a method for manufacturing a current collector for a fuel cell, wherein a current collector material is compression molded to manufacture a current collector for a fuel cell. Filling the current collector material into a first mold for shaping a shape, and compressing and molding the current collector material with the first mold while depressurizing the inside of the first mold; Filling the material molded in the above step into a second mold for molding corresponding to the shape of the current collector, and compressing and molding the material by the second mold; And a step of forming a body.

[0011] According to this configuration, since the inside of the first mold is performed while reducing the pressure in the first step, the current collector material filled in the first mold is compressed without leaving air bubbles. Molding can be performed. Therefore, the current collector manufactured through the first step and the subsequent steps is free from peeling or swelling. Further, according to this configuration, when the first mold is a porous mold for decompression, it is difficult to apply high pressure by the first mold. By compression-molding the electric material, high-pressure compression molding becomes possible. For this reason, the filling property of the current collector can be improved.

According to a third aspect of the present invention, there is provided a fuel cell current collector manufacturing apparatus for manufacturing a fuel cell current collector by compressing and molding a current collector material. A compression means for providing a molding die corresponding to the shape of the current collector, wherein the compression means press-molds the current collector material with the mold in a state where the current collector material is filled in the mold; A pressure reducing unit configured to reduce the pressure inside the mold when the compression molding is performed.

According to this structure, the inside of the mold is decompressed by the decompression means while the compression molding is performed by the compression means. Therefore, compression molding can be performed without leaving air bubbles in the current collector material filled in the mold. Therefore, a current collector without peeling or swelling can be manufactured.

[0014] In the apparatus for manufacturing a current collector for a fuel cell according to the third aspect of the present invention, the current collector material is a heat-expandable graphite powder or a material containing the heat-expandable graphite powder.
The current collector includes a convex portion for forming a groove, further,
The projecting portion has a taper angle of 10 degrees or more,
And a protruding end having a corner of a radius of 0.2 mm or more.

According to this configuration, it is possible to prevent the occurrence of a defect at the time of releasing the mold when the thermally expandable graphite powder or a material containing the thermally expandable graphite powder is used as the current collector material. Therefore, the moldability of the current collector can be improved.

In the fuel cell current collector manufacturing apparatus according to the third aspect of the present invention, the current collector material is a material having a natural graphite powder and a binder, and the mold has a groove formed in the current collector. And a protrusion having a tapered angle of 15 degrees or more and a protruding end having a rounded corner of 0.3 mm or more.

According to this configuration, it is possible to prevent the occurrence of a defect at the time of mold release when a material having natural graphite powder and a binder is used as the current collector material. Therefore, the moldability of the current collector can be improved.

According to a fourth aspect of the present invention, there is provided a fuel cell current collector manufacturing apparatus for manufacturing a current collector for a fuel cell by compressing and molding a current collector material. A first mold for shaping a shape, wherein the current collector material is provided in the first mold;
A first compression means for compressing and molding the current-collector material with the first mold in a state of being filled in the inside of the first mold; A pressure reducing means for reducing pressure; and a second mold for molding corresponding to the shape of the current collector, wherein the material molded by the first compressing means is set inside the second mold and the second mold is provided. And a second compression means for compression-molding with a second mold.

According to this configuration, the first compression means
Since compression molding is performed by the first mold while depressurizing the inside of the first mold, it is possible to perform compression molding without leaving bubbles in the current collector material filled in the first mold. it can. For this reason, the current collector manufactured through the first compression unit and the second compression unit does not peel or swell.
Further, according to this configuration, when the first mold is a porous mold for decompression, it is difficult to pressurize the first mold at high pressure. By compression-molding the current collector material, high-pressure compression molding becomes possible. For this reason, the filling property of the current collector can be improved.

[0020] In the fuel cell current collector manufacturing apparatus according to the fourth aspect of the present invention, the current collector material is a thermally expanded graphite powder or a material containing a thermally expanded graphite powder. The current collector is provided with a convex portion for forming a groove, and the convex portion further includes a draft having a taper angle of 10 degrees or more, and a protruding end portion having a radius of 0.2 mm or more. A configuration may be provided.

According to this configuration, it is possible to prevent the occurrence of a defect when the second mold is released from the mold when the current-expanding graphite powder or the material containing the heat-expandable graphite powder is used as the current collector material. it can. Therefore, the moldability of the current collector can be improved.

In the apparatus for manufacturing a current collector for a fuel cell according to the fourth aspect of the present invention, the current collector material is a material having a natural graphite powder and a binder, and the second mold is a material having A convex portion for forming a groove, wherein the convex portion has a taper angle of 15 degrees or more;
and a protruding end having a radius of at least m.

According to this configuration, it is possible to prevent occurrence of a defect when the second mold is released from the mold when a material containing natural graphite powder and a binder is used as the current collector material. Therefore, the moldability of the current collector can be improved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the present invention will be described below.

First, the structure of the polymer electrolyte fuel cell 10 using the current collector manufactured by the method for manufacturing a current collector for a fuel cell as the first embodiment will be described first. FIG.
1 is a structural diagram of the polymer electrolyte fuel cell 10. FIG. As shown in the figure, a polymer electrolyte fuel cell 10 has an electrolyte membrane 11, a cathode 12 and an anode 13 as gas diffusion electrodes having a sandwich structure with the electrolyte membrane 11 sandwiched from both sides, and the sandwich structure. A current collector 15 is provided between the cathode 12 and the anode 13 to form a material gas and fuel gas flow path while being sandwiched from both sides.

The electrolyte membrane 11 is an ion-exchange membrane formed of a polymer material, for example, a fluorine-based resin, and has good electric conductivity in a wet state. Here, Nafion (trade name, manufactured by EI DuPont, USA) is used.
The cathode 12 and the anode 13 are formed of carbon cloth woven with a yarn made of carbon fiber, and the surface of the carbon cloth has a carbon powder carrying platinum as a catalyst or an alloy of platinum and another metal. Is applied.

The carbon powder supporting platinum is prepared by the following method. An aqueous chloroplatinic acid solution and sodium thiosulfate are mixed to obtain an aqueous solution of a platinum sulfite complex. While stirring the aqueous solution, the aqueous hydrogen peroxide is removed to precipitate colloidal platinum particles in the aqueous solution. Next, carbon black serving as a carrier (for example, Vulcan XC-
While adding 72 (trademark of CABOT, USA) or Denka Black (trademark of Denki Kagaku Kogyo Co., Ltd.), stirring is performed to attach colloidal platinum particles to the surface of carbon black. Next, the solution is subjected to suction filtration or pressure filtration to separate the carbon black to which the platinum particles have adhered, washed repeatedly with deionized water (pure water), and completely dried at room temperature.

Next, after the aggregated carbon black is pulverized by a pulverizer, it is heated at 250 ° C. to 350
By heating at about 2 ° C. for about 2 hours, the platinum on the carbon black is reduced and the remaining chlorine is completely removed, thereby completing the carbon powder carrying platinum. Here, it is manufactured such that the weight of platinum is 20% (% by weight) with respect to the weight of carbon black.

The current collector 15 is formed of a dense carbon plate. A plurality of ribs extending linearly or in a grid are formed on the current collector 15, and the ribs and the surface of the cathode 12 form an oxygen-containing gas flow path 15a forming a flow path of an oxygen-containing gas as a material gas. And a hydrogen-containing gas flow path 15b serving as a flow path of a mixed gas of hydrogen gas and water vapor as a fuel gas is formed by the rib and the surface of the anode 13. The method for manufacturing the current collector 15 will be described later in detail.

The electrolyte membrane 11 and the cathode 1 described above
2, the anode 13 and the current collector 15 are configured as a single cell of the polymer electrolyte fuel cell 10;
5, a plurality of sets (two sets in FIG. 1) of the cathode 12, the electrolyte membrane 11, the anode 13, and the current collector 15 are laminated in this order, and the polymer electrolyte fuel cell 10 is constituted. The current collector located at the junction of two cells adjacent to each other has an oxygen-containing gas channel 15a on one surface and a hydrogen-containing gas channel 15b on the other surface. An electric body also serves as a flow path for both cells.

The polymer electrolyte fuel cell 10 having the above configuration
Hereinafter, a method for manufacturing the current collector 15 will be described in detail. The current collector 15 is manufactured using a powder of thermally expanded graphite manufactured as described below. A natural flaky graphite powder is prepared, and the graphite powder is immersed in concentrated sulfuric acid, concentrated nitric acid, a mixed acid, or the like to wet oxidize the graphite powder. Thereafter, when this graphite powder is rapidly heated at a high temperature of 900 ° C. or more, the distance between the layers in the graphite crystal structure expands 50 to 500 times, and the bulk density becomes 0.005 to 0.05.
5 g / cm ² of thermally expanded graphite powder is formed. The current collector 15 is manufactured using the thermally expanded graphite powder as a material.

FIG. 2 is a configuration diagram showing a sectional shape of a press jig 20 as a current collector manufacturing apparatus used for manufacturing the current collector 15. As shown in FIG.
Is a cylindrical die 22, an upper die 24 and a lower die 26 fitted into the die 22, an upper slide 28 fixed to the upper die 24 and moving the upper die 24 up and down, and a lower die 2.
Lower slide 30 fixed to 6 and moving lower die 26 up and down
And

The upper mold 24 and the lower mold 26 are made of a sintered metal porous mold (pore diameter: about 7 [μm], porosity: 25 [%]).
And has a pressing surface shape corresponding to the shape of the current collector 15. That is, the current collector 15 includes the oxygen-containing gas flow path 1.
5a, since the ribs forming the hydrogen-containing gas flow path 15b are formed, the protrusions 24 for forming the ribs are formed.
a, 26 a are provided on the pressing surfaces of the upper mold 24 and the lower mold 26. In addition, as shown in FIG. 3, these convex portions 24a, 26a
Has a taper angle θ of at least 10 degrees (in this embodiment, 20 degrees), and the radius R of the corner of the protruding end is equal to 0.
It is 2 [mm] or more (0.2 [mm] in this embodiment).

The upper slide 28 and the lower slide 30
It is connected to a moving mechanism (not shown) and moves up and down. As a result, the upper mold 24 and the lower mold 26 fixed to the tips of the upper slide 28 and the lower slide 30 are pushed,
The thermal expansion graphite powder set between the upper mold 24 and the lower mold 26 is compression molded. The upper slide 28 and the lower slide 30 have through holes 28 for air release extending in the longitudinal axis direction.
a and 30a are provided respectively. Double through hole 28
a and 30a are connected to vacuum pumps 32 and 34, respectively. By driving these vacuum pumps 32 and 34, the upper mold 24 which is in contact with the other ends of both through holes 28a and 30a.
From the lower mold 26, the pressure in the cavity surrounded by the upper mold 24, the lower mold 26, and the die 22 is reduced. Although the upper mold 24 and the lower mold 26 do not have a through-hole, since the porous mold is used as described above, the pressure in the cavity is reduced from the entire surface of the upper mold 24 and the lower mold 26. It is possible to reduce the pressure.

The upper slide 28 and the lower slide 3
O is provided with O-rings 36 and 37 for sealing the sliding portion.

Next, a method for manufacturing the current collector 15 using the press jig 20 configured as described above will be described in detail. FIG. 4 is a flowchart showing the procedure of the manufacturing method. As shown in FIG. 4, first, the lower die 30 is set at a predetermined position in the die 22 by moving the lower slide 30 upward (step S100). Here, the predetermined position is a position where the surface of the lower die 26 comes to a position slightly lower than the center of the die 22 in the vertical direction, and FIG.
This is the position indicated by the one-dot chain line. Next, the thermal expansion graphite powder as a current collector material is placed on the lower mold 26 (step S1).
10) The upper die 24 is set at a predetermined position in the die 22 (step S120). Here, the predetermined position is a position where the thermally expanded graphite powder is lightly sandwiched between the upper mold 24 and the lower mold 26, and is a position indicated by a chain line in FIG.

Thereafter, the vacuum pump 32 and the vacuum pump 34 are turned on to start reducing the pressure in the cavity surrounded by the upper die 24, the lower die 26, and the die 22 (step S130). Then, slide the upper slide 28 downward,
By moving the lower slide 30 upward and applying pressure to the upper mold 24 and the lower mold 26, a process of compression-molding the thermally expanded graphite powder is performed (step S140). The state of the press jig 20 at this time is shown in FIG. As shown in FIG. 5, the thermal expansion graphite powder PW is
6 is compression molded.

In this compression molding process, a pressure of 2 [ton / cm ² ] or more is applied. During the compression molding process, the vacuum pump 32, 34 turned on in step S130 reduces the pressure in the cavity between the upper mold 24 and the lower mold 26. At this time, the vacuum pumps 32 and 34 are operated such that the degree of vacuum in the cavity is equal to or less than the compression ratio P × 760 [torr]. here,
The compression ratio P is obtained by dividing the porosity after molding by the porosity before molding.

Returning to FIG. 4, when the compression molding process is completed in step S140, the vacuum pumps 32 and 34 are thereafter turned off (step S150), and the process of this manufacturing method is completed. As a result, the current collector 15 having the linear ribs constituting the oxygen-containing gas flow path 15a and the hydrogen-containing gas flow path 15b is manufactured from the thermally expanded graphite powder.

As described in detail above, in the first embodiment, the pressure in the cavity surrounded by the upper mold 24, the lower mold 26, and the die 22 is reduced by the vacuum pumps 32 and 34, while the upper mold 24 and the lower mold 26 is performed. Therefore, compression molding can be performed without leaving air bubbles in the thermally expanded graphite powder as the current collector material. Conventionally, if air bubbles remain in the material, after demolding, air bubbles above atmospheric pressure confined inside the molded body expand, and the surface of the molded body swells or peels off in layers, as described above. Because it can be compressed and produced without leaving air bubbles,
A current collector 15 free of surface swelling and peeling can be manufactured.

Further, by performing the compression molding while reducing the pressure as described above, the pressing speed can be improved. As a result, there is an effect that the molding cycle time can be significantly reduced.

Further, in this embodiment, since the molding pressure is 2 [ton / cm ² ] or more as described above, the density of the compact is substantially saturated, and as shown in FIG. The strength also shows good values.

Next, a second embodiment of the present invention will be described. The second embodiment relates to a fuel cell having the same configuration as the polymer electrolyte fuel cell 10 of the first embodiment, and the method of forming the current collector 15 used in the polymer electrolyte fuel cell 10 is the same as that of the first embodiment. This is different from the first embodiment.

The method of manufacturing the current collector according to the second embodiment is different from the first embodiment in that the current collector is formed in a single compression step and is formed in a first compression step in which the molding pressure is relatively low. The molding is performed in two compression steps including a second compression step in which the pressure is high.

FIG. 7 is a flowchart showing the procedure of the method of manufacturing the current collector according to the second embodiment. As shown in FIG. 7, the process of the manufacturing method includes a first-stage compression process and a second-stage compression process. When the process starts, first,
The process proceeds to the first-stage compression step, and a first press jig used in the first-stage compression step is prepared (step S200).
FIG. 8 shows a state in which the thermal expansion graphite powder PW is pressed and compressed by using the first press jig 310. As shown in FIG. It has almost the same configuration as the press jig 20 used in the first embodiment, and includes a die 322, an upper die 324, a lower die 326, and an upper slide 32.
8. Lower slide 330 and vacuum pumps 332, 334
Is provided. The difference from the press jig 20 of the first embodiment is that the upper die 324 and the lower die 326
It does not correspond to the shape of the current collector to be manufactured as in the embodiment, but has a simple planar shape.

Using the first press jig 310 having such a configuration, steps S100 to S15 of the first embodiment are performed.
The same processing as 0 is executed. First, the lower mold 326 is set at a predetermined position (step S210), and the thermally expanded graphite powder P is set.
W is placed on the lower mold 326 (step S220), and the upper mold 324 is set at a predetermined position. Then, vacuum pump 3
32 and 334 are turned on (step S240), and pressure is applied to the upper mold 324 and the lower mold 326 to execute a compression molding process (step S250).

In this compression molding process, 2 [ton / cm
² ] or less, preferably 0.5 to 1 [ton / cm ² ]
Pressure is applied. The vacuum pumps 332, 334
The degree of vacuum of the cavity part to be decompressed is set to a compression ratio P × 760 [torr] or less, which is the same as in the first embodiment.

As a result of the first-stage compression step from step S200 to step S250 having such a configuration, the thermally expanded graphite powder PW is compression-molded to form a flat molded plate.

When the processing in the first-stage compression process is completed, the process proceeds to the second-stage compression process, and a process for preparing a second press jig to be used in the second-stage compression process is performed (step S1). S260).

FIG. 9 shows a state in which the thermally expandable graphite powder PW is pressed and compressed by using the second press jig 410. As shown in FIG.
Has a die 422, an upper die 424, a lower die 426, an upper slide 428, and a lower slide 430. This second
The press jig 410 of this embodiment is different from the press jig 20 of the first embodiment in that the press jig 410 is not provided with a configuration for reducing the pressure in the cavity.
By moving 0, pressure is applied to the upper mold 24 and the lower mold 26, and only the compression molding of the material sandwiched between the upper mold 424 and the lower mold 426 is performed.

The upper mold 424 and the lower mold 426 are dense molds having high rigidity (for example, SKD molds).
It has a pressing surface shape corresponding to the shape of the current collector 15. The pressing surface has a convex portion for forming a rib, and the convex portion has a taper angle θ of 10 mm or more (20 degrees in this embodiment) as in the first embodiment. And the radius R of the corner of the protruding end is 0.2 [mm] or more (0.2 [mm] in this embodiment).

Using the second press jig 410 having such a configuration, first, the lower mold 426 is set at a predetermined position (step S210), and then the first press jig 31 is set.
0 is placed on the lower mold 426 (step S2).
20) The upper mold 424 is set at a predetermined position. As a result, the formed plate is lightly sandwiched between the upper mold 424 and the lower mold 426. Next, the upper mold 424 and the lower mold 4
A process of compressing and forming the above-mentioned formed plate by applying pressure to 26 is performed (step S250). In this compression molding process, a pressure of 3 [ton / cm ² ] or more is applied.

As a result of the second-stage compression process from step S260 to step S295 having such a configuration, the forming plate obtained in the first-stage compression process is compression-molded to provide ribs constituting a gas flow path. The current collector 15 is formed.

As described in detail above, in the second embodiment, the pressure in the cavity surrounded by the upper die 324, the lower die 326, and the die 322 is reduced by the vacuum pumps 332 and 334, and the first compression step is performed. Are doing. For this reason,
The compression molding is performed without leaving air bubbles in the thermally expanded graphite powder PW. Therefore, similarly to the first embodiment, it is possible to manufacture the current collector 15 without surface swelling or peeling, and furthermore, it is possible to increase the pressing speed and shorten the molding cycle time.

Further, in this embodiment, the molding is performed in two compression steps of the first compression step at a relatively low molding pressure and the second compression step at a high molding pressure.
High-pressure compression molding becomes possible. That is, since the upper mold 24 and the lower mold 26 used for the first press jig 310 are porous, it is difficult to apply a pressure of 3 [ton / cm ² ] or more due to rigidity. As in this embodiment, high-pressure compression molding can be realized by applying a high pressure of 3 [ton / cm ² ] or more in the ^second compression step. For this reason, it is possible to form a good current collector 15 sufficiently filled up to the tip of the rib.

In the first and second embodiments, the pressing surfaces of the upper dies 24, 424 and the lower dies 26, 426 have convex portions for forming ribs. As described above, the taper angle θ of the margin is 10
Degrees (in this embodiment, 20 degrees) and the radius R of the corner of the protruding end is 0.2 [mm] or more (in this embodiment, 0.2 mm).
[Mm]). With this configuration, the current collector 15
Can be prevented from occurring when the mold is released from the mold. Therefore, the moldability of the current collector 15 can be improved.

The preferred size of the taper angle θ of the marginal portion of the convex portion and the radius R of the corner portion of the protruding portion differ depending on the material of the current collector 15. That is, the preferable size differs between the material using the thermal expansion graphite powder as in the first and second embodiments and the material obtained by adding the binder to the natural graphite powder. The preferable size of the taper angle θ in the convex portion also differs depending on the type of the flow channel to be formed. That is, the taper angle θ depends on the case of a straight groove formed of linear ribs as in the first and second embodiments and the case of a lattice groove formed by regularly arranging cubic projections vertically and horizontally.
Have different preferred sizes.

Table 1 below shows preferable taper angles θ and R in each case based on the above relations.

[0059]

[Table 1]

By using the upper mold and the lower mold satisfying the conditions shown in Table 1, a current collector excellent in moldability can be manufactured as described above. The use of such upper and lower dies, in addition to improving moldability,
The filling property of the rib portion of the current collector is improved, and as a result, the buckling strength of the rib portion is also improved.

Using the compression molding method shown in the second embodiment, the upper die 424 and the lower die 4
For the current collector manufactured by changing the taper angle θ of the 26 withdrawal portion, the amount of deflection of the rib when pressed at a surface pressure of 40 [kg / cm ² ] was measured. The result is shown in the graph of FIG. It was shown to. The current collector material at this time was a thermally expanded graphite powder, and the molding pressure by the first pressing jig 310 was 1 [ton /
cm ² ], and the molding pressure by the second press jig 410 is 3
[Ton / cm ² ], and the channel groove formed in the current collector 15 was a lattice groove having a width of 1 [mm] vertically and horizontally.

As can be seen from FIG. 10, when the current collector material is a thermally expanded graphite powder and the channel groove is a lattice groove, when the taper angle θ becomes 15 degrees or more, the amount of deflection of the rib is sharply reduced. Become.

Binder (thermosetting resin) added to natural graphite powder
A current collector material was used as the material to which 10% was added, and the current collector was formed in the same manner as in the above example (only the molding pressure by the second press jig 410 was changed to 1 [ton / cm ² ]). Manufactures
Also for the current collector, the amount of deflection of the rib when pressed at a surface pressure of 40 [kg / cm ² ] was measured. FIG. 11 is a graph showing the measurement results.

As can be seen from FIG. 11, when the current collector material is obtained by adding a binder of 10% to natural graphite powder, and the channel groove is a lattice groove, the taper angle θ is not less than 20 degrees. When this happens, the amount of deflection of the rib suddenly decreases.

The results of these tests shown in FIGS. 10 and 11 indicate that the use of an upper die and a lower die satisfying the conditions shown in Table 1 enables the formation of a current collector having excellent buckling strength of the rib portion. Support what can be done.

Although several embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and may be implemented in various modes without departing from the gist of the present invention. Obviously you can get it. For example, instead of the polymer electrolyte fuel cell, a configuration may be used in which a current collector used for a phosphoric acid type or a molten carbonate type fuel cell is manufactured.

Further, the current collector material may be replaced with the heat-expanded graphite powder, and a material in which a thermosetting resin is mixed with the heat-expanded graphite powder may be used. When a two-stage compression process shown in the second embodiment is performed using a material obtained by blending a thermosetting resin with the thermally expanded graphite powder, in the first stage compression process, no heat treatment is performed and the second stage compression process is not performed. By applying heat treatment in the compression process,
The thermosetting resin is cured.

Further, the upper dies 24 and 324 and the lower dies 2
6,326 may be replaced with a sintered metal porous mold, and a ceramic porous mold may be used.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a polymer electrolyte fuel cell 10 using a current collector manufactured by a manufacturing method according to a first embodiment.

FIG. 2 is a configuration diagram showing a cross-sectional shape of a press jig 20 as a current collector manufacturing apparatus used in the manufacturing method.

FIG. 3 is an explanatory view showing shapes of convex portions formed on an upper mold 24 and a lower mold 26;

FIG. 4 is a flowchart showing a procedure of a method for manufacturing a current collector.

FIG. 5 is a configuration diagram showing a cross-sectional shape of the press jig 20 in a state where compression is performed.

FIG. 6 is a graph showing a relationship between a molding pressure and a bending strength of a current collector.

FIG. 7 is a flowchart illustrating a procedure of a method for manufacturing a current collector according to the second embodiment.

FIG. 8 is a configuration diagram showing a cross-sectional shape of a first press jig 310 in a state where pressure compression is performed in a second embodiment.

FIG. 9 is a configuration diagram showing a cross-sectional shape of a second press jig 410 in a state where pressure compression is performed in the second embodiment.

FIG. 10 is a graph showing a change in the amount of deflection of a rib when a taper angle θ of a margin of a convex portion of a mold is changed for a current collector manufactured from thermally expanded graphite powder.

FIG. 11 is a graph showing a change in the amount of deflection of a rib when a taper angle θ of a margin of a protrusion of a mold is changed for a current collector manufactured from a material obtained by adding a binder to natural graphite powder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Solid polymer type fuel cell 11 ... Electrolyte membrane 12 ... Cathode 13 ... Anode 15 ... Current collector 15a ... Oxygen-containing gas channel 15b ... Hydrogen gas channel 15b ... Hydrogen-containing gas channel 20 ... Press jig 22 ... Die die 24 ... Upper die 26 ... Lower die 28 ... Upper slide 28a, 30a ... Through hole 30 ... Lower slide 32, 34 ... Vacuum pump 36, 37 ... O-ring 310 ... First press jig 322 ... Die die 324 ... Upper die 326 ... Lower die 328 ... Upper slide 330 ... Lower slide 332, 334 ... Vacuum pump 410 ... Second press jig 422 ... Die die 424 ... Upper die 426 ... Lower die 428 ... Upper slide 430 ... Lower slide

Claims (8)

[Claims] 1. A fuel cell collector for manufacturing a fuel cell current collector by filling a current collector material into a molding die and compressing and molding the current collector material with the die. A method for manufacturing a current collector for a fuel cell, comprising a step of performing compression molding using the mold while reducing the pressure inside the mold. 2. A method for manufacturing a current collector for a fuel cell, wherein a current collector material is compression-molded to manufacture a current collector for a fuel cell, wherein the current collector is formed inside a first mold for molding having a predetermined shape. Filling the current collector material, compressing and molding the current collector material with the first mold while depressurizing the inside of the first mold; and forming a second mold for molding corresponding to the shape of the current collector. A step of filling the material molded in the above step into the inside of the second mold and compressing and molding the material with the second mold to form the current collector. A method for manufacturing a current collector for a battery. 3. A fuel cell current collector manufacturing apparatus for manufacturing a current collector for a fuel cell by compression-molding a current collector material, comprising a molding die corresponding to the shape of the current collector. Compression means for compressing and molding the current collector material by the mold in a state where the current collector material is filled in the mold; and decompression for reducing the pressure inside the mold when the compression molding is performed by the compression means. Means for producing a current collector for a fuel cell. 4. The apparatus for manufacturing a current collector for a fuel cell according to claim 3, wherein the current collector material is a thermally expanded graphite powder or a material containing a thermally expanded graphite powder. The current collector has a convex portion for forming a groove, and the convex portion further includes: a draft having a taper angle of 10 degrees or more; and a protruding end having a radius of 0.2 mm or more. For manufacturing a current collector for a fuel cell. 5. The apparatus for manufacturing a current collector for a fuel cell according to claim 3, wherein the current collector material is a material having a natural graphite powder and a binder, and the mold is provided on the current collector. A projection for forming a groove; and a projection for a fuel cell, the projection including: a draft having a taper angle of 15 degrees or more; and a projection having a radius of 0.3 mm or more. Electric body manufacturing equipment. 6. An apparatus for manufacturing a current collector for a fuel cell, wherein a current collector material is compression-molded to manufacture a current collector for a fuel cell, comprising: a first mold for molding having a predetermined shape; A first compression unit for compressing and molding the current collector material by the first mold in a state where the current collector material is filled in the first mold; First
A pressure reducing means for reducing the pressure inside the mold, and a second mold for molding corresponding to the shape of the current collector,
A current collector for a fuel cell, comprising: a second compression means for compression-molding the material molded by the first compression means by the second mold in a state where the material is set inside the second mold. Manufacturing equipment. 7. The apparatus for manufacturing a current collector for a fuel cell according to claim 6, wherein the current collector material is a thermally expanded graphite powder or a material containing a thermally expanded graphite powder. The mold has a convex portion for forming a groove in the current collector, and the convex portion has a draft having a taper angle of 10 degrees or more, and a tip having a radius of 0.2 mm or more. And a manufacturing apparatus for a current collector for a fuel cell, comprising: 8. The apparatus for manufacturing a current collector for a fuel cell according to claim 6, wherein the current collector material is a material having a natural graphite powder and a binder; A fuel provided with a protrusion for forming a groove in the electric body; and a protrusion having a taper angle of 15 degrees or more, and a protrusion having a radius of 0.3 mm or more. Manufacturing equipment for battery current collectors.