JP2006164889A - Method of manufacturing fuel cell separator using carbon, fuel cell separator, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a fuel cell separator with high performance, capable of reducing cost, and to provide a fuel cell separator and the fuel cell. <P>SOLUTION: The fuel cell separator held in a prescribed shape by impregnating a sheet-shaped carbon W1 with a shape retaining material 40 is manufactured by the manufacturing method of a fuel cell separator comprising an impregnation process forming a sheet-shaped separator material W2 by impregnating a sheet-shaped carbon W1 with a shape retaining material 40, and a pressing process forming the separator by pressing the sheet-shaped separator material W2. The fuel cell is manufactured by using the fuel cell separator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a separator used in a fuel cell, a fuel cell separator, and a fuel cell.

  As a method for manufacturing a fuel cell separator, there is a method in which a powdered molding material is compression-molded with a mold (see, for example, Non-Patent Document 1). However, this method has the disadvantages that the thickness of the separator to be molded tends to vary, the cycle time is long, and it is difficult to automate and unmanned.

The variation in the separator plate thickness causes leakage of fuel gas, air, etc. in the fuel cell, and also causes an increase in electrical resistance between the separator and adjacent members. This is an output per volume, which is a cause of lowering (which is an index for evaluating the quality of a fuel cell that requires miniaturization and high output).
"Fiscal 2001 Results Report Research and Development of Solid Polymer Fuel Cell Development of Carbon Resin Mold Separator (for Public Use)", [online], March 2002, New Energy and Industrial Technology Development Organization, Consignment Destination: Mitsubishi Electric Corporation, Internet <URL: http://www.tech.nedo.go.jp/>

  The present invention has been made to solve the problems associated with the above-described conventional technology, and provides a high-quality manufacturing method of a fuel cell separator, a fuel cell separator, and a fuel cell that can reduce costs. Objective.

  The manufacturing method of a fuel cell separator according to the present invention that achieves the above object includes an impregnation step of impregnating a sheet-like carbon with a shape-retaining material to form a sheet-like separator material, and pressing the sheet-like separator material to remove the separator. And a pressing step for molding.

  The fuel cell separator according to the present invention that achieves the above object is characterized in that a sheet-like carbon is impregnated with a shape-retaining material and held in a predetermined shape.

  A fuel cell according to the present invention that achieves the above object includes a separator for a fuel cell that is held in a predetermined shape by impregnating a sheet-like carbon with a shape-retaining material.

  Since the manufacturing method of the separator for a fuel cell according to the present invention configured as described above is pressed using sheet-like carbon instead of a powdery molding material, a separator with good dimensional accuracy can be produced.

  The fuel cell separator according to the present invention configured as described above can retain the shape of the carbon separator because the carbon material is impregnated with the shape maintaining material, and is excellent in conductivity.

  The fuel cell according to the present invention configured as described above has excellent output performance since the dimensional accuracy of the separator is good, and leakage of fuel gas, air, and the like hardly occurs.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a principal part showing a single cell of a fuel cell according to the present invention.

  A fuel cell is formed by assembling a large number of unit cells 10 as shown in FIG. 1 in the form of a stack, and is used, for example, as a drive source for an automobile.

  The single cell 10 is a device that can obtain electricity in the process of obtaining water by reacting hydrogen and oxygen by utilizing the reverse principle of electrolysis of water, and includes a membrane electrode assembly 20 and a gas diffusion layer 21A. , 21B and separators 30A, 30B. The membrane electrode assembly 20 is formed by arranging electrodes on which catalyst layers are formed on both sides of a solid polymer membrane. The gas diffusion layers 21 </ b> A and 21 </ b> B are disposed on both surfaces of the membrane electrode assembly 20. Separator 30A, 30B is arrange | positioned on the outer surface of gas diffusion layer 21A, 21B.

  The separators 30A and 30B have a shape in which a plurality of concave and convex grooves are continuous, and in the separator 30A, a cooling water channel groove 31A for circulating cooling water and a fuel gas for circulating fuel gas (hydrogen). The flow channel grooves 32 are formed alternately. The separator 30B is alternately formed with a cooling water channel groove 31B for circulating cooling water and an oxidant channel groove 33 for circulating oxidizing gas (oxygen).

  The separators 30A and 30B are carbon materials that are completely or partially impregnated with a shape retention material, and for example, a thermosetting resin or a thermoplastic resin is used as the shape retention material. Since the separators 30A and 30B need to conduct current, it is preferable that the shape retaining material also has high conductivity.

  FIG. 2 is a perspective view showing the material of the separator, (A) is a perspective view showing the sheet-like carbon, and (B) is a perspective view showing the sheet-like separator material.

  The separator 30 is formed by first impregnating the sheet-like carbon W1 with the shape holding material 40 to form the sheet-like separator material W2 (see FIG. 2), and processing the sheet-like separator material W2 into a predetermined shape. The In FIG. 2B, the impregnated portions are virtually stacked for convenience for easy understanding of the state impregnated with the shape-retaining material.

<Method for forming sheet separator material>
For example, the sheet-like carbon W1 has a thickness of 0.01 to 1.0 mm, a density of 0.8 to 2.0 g / cm ³ , an electric conductivity of 0.05 to 1.0 mΩ / cm, and a heat resistance of 100 ° C. It is a carbon material formed in the above sheet shape.

  The reason why the shape holding material 40 is impregnated into the sheet-like carbon W1 is to reliably hold the shape obtained by press-molding carbon.

  The method of impregnating the shape-holding material 40 into the sheet-like carbon W1 is different between, for example, a thermosetting resin and a thermoplastic resin.

  When the thermosetting resin is used, the sheet-like carbon W1 is impregnated with a curable resin dissolved in a solvent to form a varnish, and then dried to volatilize the solvent, thereby forming the sheet-like separator material W2. As the thermosetting resin, for example, a phenol resin, an epoxy resin, an unsaturated polyester, or the like can be used.

  When the thermoplastic resin is used, the sheet-like carbon W1 is impregnated with the heat-melted thermoplastic resin and then cooled to form the sheet-like separator material W2. As the thermoplastic resin, for example, Teflon (registered trademark), polyester, polyphenylene sulfide, silicon, olefin-based (PP, PE, etc.), polyamide, polyvinylidene fluoride, polyimide, ethylene vinyl acetate, or the like can be used.

  In the above impregnation method, vacuum impregnation, dripping impregnation, or printing impregnation is appropriately used according to the characteristics of the shape-retaining material 40, and is performed on the entire surface of the sheet-like carbon W1 or partially. The advantage of partly impregnating is that the part necessary for maintaining the shape of the separator after molding is impregnated, and the part that conducts electricity in contact with other members is not impregnated. It can be increased. The advantages of impregnating the entire surface are that the impregnation step is easy, the shape of the separator after molding can be reliably maintained, and the conductivity is relatively excellent.

  When the sheet-like carbon W1 is partially impregnated, printing impregnation is preferable.

  FIG. 3 is a diagram showing a state in which sheet-like carbon is partially impregnated, (A) is a perspective view in which a form frame is provided on sheet-like carbon, and (B) is a state in which sheet-like carbon is impregnated with resin. The side view to show, (C) is a perspective view which shows the sheet-like separator material impregnated partially.

  First, as shown in FIG. 3 (A), the sheet-like carbon W1 is covered with a mold 50 provided with an opening 51, and from above, varnish-like thermosetting is performed as shown in FIG. 3 (B). Or a thermoplastic resin that has been melted by heating is discharged from the nozzle 52. In this way, the shape retaining material 40 is printed and impregnated in the portion where the sheet-like carbon W1 coincides with the opening 51, and the impregnated portion 35 and the non-impregnated portion 36 are alternately formed (see FIG. 3C). .

  This operation is performed on both surfaces or one surface of the sheet-like carbon W1, but in the case of both surfaces, it is also possible to provide the nozzles 52 on both surfaces and impregnate them simultaneously (not shown). Usually, when impregnation is performed, not only the inside of the sheet-like carbon W1 but also the shape retaining material 40 often remains on the surface, so the resin of the shape retaining material 40 is removed depending on the case. It is preferable.

  The mold 50 can be arbitrarily changed according to a desired sheet-like separator material W2, and by this change, a desired portion of the sheet-like carbon W1 can be impregnated.

<Method of molding separator>
In order to form the separator 30 by pressing the sheet-like separator material W2 formed as described above, the following method is used.
<First Embodiment>
The first embodiment is a separator molding method in the case where a thermosetting resin is used for the shape-retaining material 40, and can be applied to both the sheet-like separator material W2 impregnated on the entire surface or a part thereof.

  FIG. 4 is a cross-sectional view showing a processed state of the sheet-like separator material by the mold according to the first embodiment, (A) is a cross-sectional view showing a state before processing, and (B) is a cross-sectional view showing a state after processing. FIG.

  First, the upper mold 61 and the lower mold 62 are made of the thermosetting resin (shape holding material) 40 used for the sheet-like separator material W2 by the heating source 63 provided in the upper mold 61 and the lower mold 62. Heat above the curing temperature.

  Next, as shown in FIG. 4A, a sheet-like separator material W2 is placed on the lower mold 62. Thereafter, as shown in FIG. 4B, the upper mold 61 and the lower mold 62 are brought close to each other to press the sheet-like separator material W2, and are held in this state. During this time, the thermosetting resin is cured and then cured. The upper mold 61 and the lower mold 62 are held until the time necessary for the thermosetting resin to cure is passed, and then the separator 30 molded by releasing is taken out.

  FIG. 5 is a cross-sectional view showing a sheet-like separator material and a separator impregnated on the entire surface, (A) is a main-part cross-sectional view showing the sheet-like separator material impregnated on the entire surface, and (B) is a molded separator. The principal part sectional drawing shown, (C) is the principal part sectional drawing from which the resin of the surface was removed.

  When the sheet-like separator material W2 is processed, as shown in FIG. 5B, the thermosetting resin 40 is left on the surface of the contact surface 34 in contact with the adjacent member of the molded separator 30. In this case, in order to ensure conductivity when the contact surface 34 comes into contact with another member, the surface thermosetting resin 40 is removed by shot peeling or the like (see FIG. 5C). Thereby, the carbon material of the separator 30 impregnated with the thermosetting resin 40 can be in direct contact with the adjacent member. In addition, when removing the thermosetting resin 40 remaining on the surface, not only the contact surface 34 but the entire surface of the separator 30 may be used, and the sheet-like separator material W2 (see FIG. 5A). It may be performed at the stage.

  Usually, when the sheet-like carbon W1 is not impregnated with the thermosetting resin 40, it is difficult to maintain the shape of the separator 30 after press working due to the characteristics of the carbon material. Since the thermosetting resin 40 is impregnated, the shape can be reliably maintained even after the press working.

  Moreover, since the material of the separator 30 according to the method of the present embodiment is not a powder but a plate shape, the dimensional accuracy in the plate thickness direction is good, and the separator 30 can be in good contact with an adjacent member.

  For example, when a metal is used for a separator, a noble metal is coated to prevent corrosion. However, carbon impregnated with resin does not have a problem of corrosion, so there is no need to apply a noble metal coating, and the cost can be reduced. .

  In addition, the method according to the present embodiment can shorten the cycle time compared with the method of compression molding a powdery material, and can reduce costs because it is easy to automate and unmanned. .

  Also, in transfer molding and injection molding in which the material is flowed by pressure and filled into the mold cavity, waste material is generated by sprues and runners that serve as resin paths in the mold, and the equipment and mold are expensive. However, compared with these methods, the method according to the present embodiment does not generate waste materials, and the cost can be reduced because the equipment and the mold are inexpensive.

  FIG. 6 is a cross-sectional view showing a separator processed by a partially impregnated sheet-like separator material, (A) is a main part cross-sectional view showing a partially impregnated sheet-like separator material, and (B) It is principal part sectional drawing which shows the shape | molded separator.

  When the sheet-shaped separator material W2 partially impregnated with the resin is processed, the non-impregnated portion 36 not impregnated with the resin is in contact with the adjacent member of the separator 30 as shown in FIG. It can be. In addition to the effect of the separator 30 using the sheet separator material W2 in which the entire surface is impregnated with the thermosetting resin 40, the separator 30 formed in this way is further impregnated with resin in the non-impregnated portion 36. Therefore, conductivity is better. Further, since the back surface of the non-impregnated portion 36 is impregnated with resin, the shape of the separator 30 can be reliably maintained and leakage of cooling water, fuel gas, and oxidant gas can be suppressed.

  FIG. 7 is a cross-sectional view showing the main part of a fuel cell using a separator partially impregnated with resin.

  As shown in FIG. 7, the fuel cell is formed by assembling a large number of single cells 10 in the form of a stack. The arrows in FIG. 7 exemplify paths through which current flows in the fuel cell. The separator 30 according to the present embodiment has excellent dimensional accuracy and is in good contact with an adjacent member, and since the non-impregnated portion 36 is not impregnated with the thermosetting resin 40, the contact resistance is reduced and the electrical resistance is reduced. In addition, the output density of the fuel cell can be improved. Further, leakage of cooling water, fuel gas, and oxidant gas can be reduced by the thermosetting resin 40 impregnated in the impregnation portion 35.

  Even in a fuel cell (not shown) using the separator 30 (see FIG. 5C) in which the entire surface is impregnated with the thermosetting resin 40, the conductivity is not as high as the separator 30 having the non-impregnated portion 36, Moreover, the shape of the separator 30 can be reliably held by the thermosetting resin 40, and leakage of cooling water, fuel gas, and oxidant gas can be more reliably suppressed.

<Second Embodiment>
The second embodiment is a method for forming a separator in the case where a thermoplastic resin is used for the shape-retaining material 40. The mold and processes are somewhat different from those of the first embodiment in which a thermosetting resin is used for the shape-retaining material. Different.

  The separator molding method of the present embodiment can be applied to both the whole or partly impregnated sheet-like separator material W2.

  FIG. 8 is a side view showing a heating source in the second embodiment, FIG. 9 is a cross-sectional view showing a processing state of a sheet-like separator material by a mold in the second embodiment, and (A) is a state before processing. (B) is sectional drawing which shows the state after a process. In addition, about the member which has the same function as 1st Embodiment, the same code | symbol is used and the description is abbreviate | omitted in order to avoid duplication.

  First, as shown in FIG. 8, the sheet-like separator material W2 impregnated with the thermoplastic resin (shape holding material) 40 is heated by a heating source 70 such as a hot plate to melt the thermoplastic resin 40. After that, the sheet-shaped separator material W2 is placed and pressed inside the upper mold 61 and the lower mold 62 that are cooled to such an extent that they are not rapidly cooled (see FIGS. 9A and 9B) and held in this state. To do. During this time, the thermoplastic resin 40 is cooled and cured by the upper mold 61 and the lower mold 62. After the time necessary for the thermoplastic resin 40 to cure has elapsed, the separator 30 is removed and the separator 30 is taken out.

  Further, without using the heating source 70 as shown in FIG. 8, the upper die 61 and the lower die 62 are heated by a heating source separately provided in the upper die 61 and the lower die 62, and the heated upper die 61 is heated. And after heating and pressurizing the sheet-like separator material W2 with the lower mold 62, the upper mold 61 and the lower mold 62 can be cooled while being held in the pressurized state.

  Thereafter, a fuel cell is formed using the molded separator 30, but the description is omitted because it is similar to the first embodiment.

<Third Embodiment>
The third embodiment is a separator molding method in which an impregnation step of impregnating a shape holding material and a pressing step of molding the separator are performed simultaneously, and a thermosetting resin is used as the shape holding material.

  FIG. 10 is a cross-sectional view showing a processing state of a sheet-like separator material by a mold in the third embodiment, (A) is a cross-sectional view showing a state before processing, and (B) is a cross-section showing a state after processing. FIG. In addition, about the member which has the same function as the above-mentioned embodiment, the same code | symbol is used and the description is abbreviate | omitted in order to avoid duplication.

  First, as shown in FIG. 10A, the sheet-like carbon W1 is sandwiched between two sheet-like thermosetting resins, and the heating source 63 determines the curing temperature of the curable resin (shape holding material) 40 to be used. It is installed inside the lower mold 62 heated to a higher temperature. Thereafter, as shown in FIG. 10B, the heated upper die 61 is brought close to the lower die 62 in the same manner as the lower die 62, and the sheet-like carbon W1 and the sheet-like thermosetting resin 41 are pressed and held. To do. As a result, 61 sheet-like carbon W1 is formed into a predetermined shape by the upper die 61 and the lower die 62, and at the same time, a thermosetting resin having heat and fluidity is pressurized and impregnated into the sheet-like carbon W1. Is done. After the time necessary for the thermosetting resin to cure and retain its shape has elapsed, the mold is released and the separator 30 impregnated with the thermosetting resin 40 is taken out.

  Thereafter, a fuel cell is formed using the molded separator 30, but the description is omitted because it is similar to the first embodiment.

<Fourth Embodiment>
As in the third embodiment, the fourth embodiment is a separator molding method in which an impregnation step for impregnating a shape-retaining material and a pressing step for molding the separator are performed simultaneously. The mold and process are slightly different from those of the third embodiment in which a resin is used and a thermosetting resin is used for the shape-retaining material.

  FIG. 11 is a side view showing a heating source in the fourth embodiment, FIG. 12 is a cross-sectional view showing a processing state of a sheet-like separator material by a mold in the fourth embodiment, and (A) is a state before processing. (B) is sectional drawing which shows the state after a process. In addition, about the member which has the same function as the above-mentioned embodiment, the same code | symbol is used and the description is abbreviate | omitted in order to avoid duplication.

  First, as shown in FIG. 11, the sheet-like carbon W1 is sandwiched between two sheet-like thermoplastic resins 42 formed in a sheet shape, and the sheet-like thermoplastic resin 42 is heated and melted by a heating source 70. Let Next, as shown in FIG. 12A, the heated sheet-like carbon W <b> 1 and the sheet-like thermoplastic resin 42 are placed inside the cooled lower mold 62. Thereafter, as shown in FIG. 12B, the upper die 61 cooled in the same manner as the lower die 62 is brought close to the lower die 62, and the sheet-like carbon W1 and the sheet-like thermoplastic resin 42 are pressed and held. . As a result, the sheet-like carbon W1 is molded into a predetermined shape by the upper die 61 and the lower die 62, and at the same time, the heated and fluid thermoplastic resin is pressurized and impregnated into the sheet-like carbon W1. . After the time necessary for the thermoplastic resin to cool and harden and retain its shape has elapsed, the mold is released and the separator 30 impregnated with the thermoplastic resin is taken out.

  Thereafter, a fuel cell is formed using the molded separator 30, but the description is omitted because it is similar to the first embodiment.

  In the fourth embodiment, after the sheet-like thermoplastic resin is heated by a separately prepared heating source, the sheet-like carbon W1 and the sheet-like thermoplastic resin 42 are installed in the mold, but the heated mold The sheet-like carbon W1 and the sheet-like thermoplastic resin 42 may be heated and pressurized simultaneously, and the mold may be cooled while the state is maintained.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the shape of the flow path groove of the separator is not limited to the rectangular shape in cross section, and may be, for example, a trapezoidal shape or an arc shape. Further, the separators 30A and 30B may not be symmetrical.

It is principal part sectional drawing which shows the single cell of a fuel cell. It is a perspective view which shows the material of a separator, (A) is a perspective view which shows sheet-like carbon, (B) is a perspective view which shows sheet-like separator material. It is a figure which shows the state which impregnates sheet-like carbon partially, (A) is a perspective view in which the formwork was provided in sheet-like carbon, (B) is a perspective view which shows the state which impregnates resin in sheet-like carbon (C) is a perspective view showing a sheet-like separator material partially impregnated. It is sectional drawing which shows the processing state of the sheet-like separator material by the metal mold | die of 1st Embodiment, (A) is sectional drawing before a process, (B) is sectional drawing after a process. It is sectional drawing which shows the sheet-like separator material and separator which were impregnated on the whole surface, (A) is principal part sectional drawing which shows the sheet-like separator material impregnated on the whole surface, (B) is principal part which shows the formed separator. Sectional drawing, (C) is a principal part sectional view from which the resin on the surface has been removed. It is sectional drawing which shows the separator processed with the sheet-like separator material impregnated partially, (A) is principal part sectional drawing which shows the sheet-like separator material impregnated partially, (B) was shape | molded It is principal part sectional drawing which shows a separator. It is sectional drawing which shows the principal part of the fuel cell using the separator which concerns on 1st Embodiment. It is a side view which shows the heating source in 2nd Embodiment. It is sectional drawing which shows the processing state of the sheet-like separator material by the metal mold | die in 2nd Embodiment, (A) is sectional drawing before a process, (B) is sectional drawing after a process. It is sectional drawing which shows the processing state of the sheet-like separator material by the metal mold | die in 3rd Embodiment, (A) is sectional drawing before a process, (B) is sectional drawing after a process. It is a side view which shows the heating source in 4th Embodiment. It is sectional drawing which shows the processing state of the sheet-like separator material by the metal mold | die in 4th Embodiment, (A) is sectional drawing before a process, (B) is sectional drawing after a process.

Explanation of symbols

10 single cell,
20 Membrane electrode assembly,
21A, 21B gas diffusion layer,
30A, 30B separator,
31A, 31B Channel groove for cooling water,
32 fuel gas channel groove,
33 Channel groove for oxidizing agent,
35 impregnation part,
36 Non-impregnated part,
40 shape retaining material,
41 sheet-like thermosetting resin,
42 sheet-like thermoplastic resin,
50 formwork,
51 opening,
52 nozzles,
60 molds,
61 Upper mold,
62 Lower mold,
63 Heat source,
70 heating source,
W1 sheet carbon,
W2 Sheet separator material.

Claims (13)

An impregnation step of impregnating a sheet-like carbon with a shape-retaining material to form a sheet-like separator material;
And a pressing step of molding the separator by pressing the sheet-like separator material.   2. The method for producing a fuel cell separator according to claim 1, wherein in the impregnation step, the shape-retaining material is partially impregnated into the sheet-like carbon.   The method for producing a separator for a fuel cell according to claim 1 or 2, wherein the impregnation step is performed by printing impregnation.   The said impregnation process is performed with the pressurization in a press process, The manufacturing method of the separator for fuel cells of any one of Claims 1-3 characterized by the above-mentioned.   The method of manufacturing a fuel cell separator according to any one of claims 1 to 4, wherein the shape retaining material is a resin.   A fuel cell separator, wherein the sheet-like carbon is impregnated with a shape-retaining material and held in a predetermined shape.   7. The fuel cell separator according to claim 6, wherein the fuel cell separator has an impregnated portion impregnated with the shape retaining material and a non-impregnated portion not impregnated with the shape retaining material. .   The fuel cell separator according to claim 6 or 7, wherein the non-impregnated portion is provided in a portion where the fuel cell separator conducts electricity with an adjacent member.   The fuel cell separator according to any one of claims 6 to 8, wherein the shape retaining material is a resin.   A fuel cell comprising a fuel cell separator in which a sheet-like carbon is impregnated with a shape-retaining material and held in a predetermined shape.   The fuel cell according to claim 10, wherein the fuel cell separator has an impregnated portion impregnated with the shape retaining material and an unimpregnated portion not impregnated with the shape retaining material.   The fuel cell according to claim 10 or 11, wherein the non-impregnated portion is provided in a portion where the fuel cell separator conducts electricity with an adjacent member.   The fuel cell according to claim 10, wherein the shape retaining material is a resin.

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