JP2010232127A - Manufacturing method of fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a fuel cell stack capable of restraining occurrence of sealing failure, while restraining increase of the number of components and weight. <P>SOLUTION: The manufacturing method of the fuel cell stack (300) includes a cell-forming process of arranging each of pair separators (30, 40) on either each side of a membrane-electrode assembly (10) with a sealing member (20) arranged at an outer periphery, a laminating process of laminating a plurality of fuel cells (100) manufactured in the cell-forming process, a stacking process of fastening the plurality of laminated fuel cells with a fastening member (340), and a process of inserting a positioning member for carrying out positioning of the pair of separators themselves at least from the cell-forming process to finish of the stacking process. As the positioning member, a sealing member or one capable of being removed after the stacking process may be used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a fuel cell stack.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. Since this fuel cell is excellent in terms of the environment and can realize high energy efficiency, it has been widely developed as a future energy supply system.

  The fuel cell stack is manufactured, for example, by arranging a pair of separators on both surfaces of the membrane-electrode assembly to form a cell, and stacking and fastening a plurality of cells. Patent Document 1 discloses a fuel cell stack including a holding pin that penetrates between a pair of separators of a fuel cell in the stacking direction of the fuel cell.

JP 2000-12067 A

  By the way, in the cell forming step, pressure in the stacking direction (hereinafter referred to as pressing force) is applied to the cell from the outside. However, this pressing force may be loosened in the lamination process. In this case, the position of the separator may be shifted due to expansion of the membrane-electrode assembly. As a result, a sealing failure may occur. Although the fuel cell stack according to Patent Document 1 can suppress a seal failure due to the position shift of the separator, the fuel cell stack includes a holding pin, so that the number of parts of the fuel cell stack increases and the fuel cell stack Becomes heavier.

  An object of the present invention is to provide a method of manufacturing a fuel cell stack that can suppress the occurrence of a seal failure while suppressing an increase in the number of parts and weight.

  A method of manufacturing a fuel cell stack according to the present invention includes a cell forming step in which a pair of separators are disposed on both surfaces of a membrane-electrode assembly having a seal member disposed on the outer periphery, and a plurality of fuel cells manufactured in the cell forming step. A positioning member for positioning a pair of separators between a stacking step of stacking, a stacking step of fastening a plurality of stacked fuel cells with a fastening member, and at least from the cell forming step to the end of the stacking step The positioning member is a seal member or a member that can be removed after the stacking step.

  According to the manufacturing method of the fuel cell stack according to the present invention, the positioning of the pair of separators is performed by the positioning member from the cell forming process to the end of the stacking process. Thereby, even if the external pressing force on the fuel cell is relaxed after the cell forming step, the position shift of the separator is suppressed. Thereby, generation | occurrence | production of the sealing defect can be suppressed. Further, since the positioning member is a seal member or a member that can be removed after the stacking process, an increase in the number of parts of the fuel cell stack and an increase in weight are suppressed.

  In the above method, the pair of separators may have a recess in which the positioning member is disposed. In the above method, the recess may have a smaller opening area than at least a part of the other area. In the above method, the concave portion may have a wall surface that receives a drag force from the positioning member when the distance between the pair of separators increases. According to this method, peeling between the pair of separators and the seal member is suppressed. Thereby, generation | occurrence | production of the sealing defect can be suppressed.

  The method may further include a removing step of removing the positioning member after the stacking step.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the fuel cell stack which can suppress generation | occurrence | production of a seal failure, suppressing the increase in a number of parts and weight increase can be provided.

FIG. 1A is a schematic cross-sectional view showing a cell forming process in the method of manufacturing a fuel cell stack according to the first embodiment. FIG. 1B is a schematic cross-sectional view of the membrane-electrode assembly. FIG.1 (c) is typical sectional drawing which shows a lamination process. FIG. 2 is a schematic cross-sectional view showing a stacking process. FIG. 3A is a schematic cross-sectional view of a fuel cell according to a comparative example. FIG. 3B is a schematic cross-sectional view of the fuel cell according to the first embodiment. FIG. 4A to FIG. 4D are schematic cross-sectional views illustrating modifications of the recess according to the first embodiment. FIG. 5A is a schematic cross-sectional view showing the stacked body after the fastening process of the stacking process in the method for manufacturing the fuel cell stack according to the second embodiment. FIG. 5B is a schematic cross-sectional view showing the removal process.

  Hereinafter, modes for carrying out the present invention will be described.

  A method for manufacturing the fuel cell stack 300 according to the first embodiment of the present invention will be described. The fuel cell stack 300 is manufactured by a process including a cell forming process, a stacking process, and a stacking process. FIG. 1A is a schematic cross-sectional view showing a cell forming process. The cell forming process is a process for manufacturing the fuel cell 100. The fuel cell 100 includes a membrane-electrode assembly 10, a seal member 20 arranged on the outer periphery of the membrane-electrode assembly 10, and a pair of membrane-electrode assemblies 10 and a pair of seal members 20 arranged so as to sandwich the seal member 20. Separators (anode separator 30 and cathode separator 40).

  FIG. 1B is a schematic cross-sectional view of the membrane-electrode assembly 10. The membrane-electrode assembly 10 includes an electrolyte membrane 11, a catalyst layer (anode catalyst layer 12 and cathode catalyst layer 13), and a gas diffusion layer (anode gas diffusion layer 14 and cathode gas diffusion layer 15). As the electrolyte membrane 11, for example, a solid polymer electrolyte having proton conductivity can be used. As a solid polymer electrolyte membrane having proton conductivity, for example, a perfluorosulfonic acid membrane can be used.

  The anode catalyst layer 12 and the cathode catalyst layer 13 are arranged so as to sandwich the electrolyte membrane 11. The catalyst of the anode catalyst layer 12 promotes protonation of hydrogen. The catalyst of the cathode catalyst layer 13 promotes the reaction between protons and oxygen. For example, the anode catalyst layer 12 and the cathode catalyst layer 13 contain platinum-supported carbon or the like.

  The anode gas diffusion layer 14 is disposed on the surface of the anode catalyst layer 12 opposite to the electrolyte membrane 11. The cathode gas diffusion layer 15 is disposed on the surface of the cathode catalyst layer 13 opposite to the electrolyte membrane 11. The anode gas diffusion layer 14 has a function of diffusing an anode gas containing hydrogen and supplying the anode gas to the anode catalyst layer 12. The cathode gas diffusion layer 15 has a function of diffusing a cathode gas containing oxygen and supplying it to the cathode catalyst layer 13. As the anode gas diffusion layer 14 and the cathode gas diffusion layer 15, for example, carbon fibers such as carbon paper and carbon cloth can be used.

  With reference to FIG. 1A, the sealing member 20 is not particularly limited as long as it is a sealing material that can suppress gas leakage from the membrane-electrode assembly 10. In this embodiment, the seal member 20 is made of a seal material that cures from a liquid or semi-solid state. The seal member 20 is disposed so as to be sandwiched between the anode separator 30 and the cathode separator 40 on the outer periphery of the membrane-electrode assembly 10. Further, the seal member 20 is also disposed in a recess 50 of an anode separator 30 and a cathode separator 40 which will be described later.

  The anode separator 30 is disposed on the anode side of the membrane-electrode assembly 10. The cathode separator 40 is disposed on the cathode side of the membrane-electrode assembly 10. In this embodiment, an anode gas channel 31 is formed on the surface of the anode separator 30 on the membrane-electrode assembly 10 side. A cathode gas channel 41 is formed on the surface of the cathode separator 40 on the membrane-electrode assembly 10 side. The anode gas channel 31 and the cathode gas channel 41 are, for example, groove channels formed on the surface of the separator.

  The anode separator 30 and the cathode separator 40 have a recess 50 in which the seal member 20 is disposed. The recess 50 has an opening on the surface on the membrane-electrode assembly 10 side. In this embodiment, the seal member 20 is injected into the recess 50 from this opening. In addition, as a material of the anode separator 30 and the cathode separator 40, conductive materials, such as a metal, are used, for example.

  The recess 50 has a shape in which the area of the opening is smaller than the area of at least a part of the other part. In this embodiment, the recess 50 has an opening on the side of the membrane-electrode assembly 10 as a top surface, a side far from the membrane-electrode assembly 10 as a bottom surface having a larger diameter than the top surface, and a diameter expanding from the top surface to the bottom surface. It has a trapezoidal pyramid shape with side surfaces. In this case, the area of the opening (top surface) is smaller than the area of the bottom surface.

  The recess 50 has a wall surface 51. The wall surface 51 is a wall surface that receives a drag force from the seal member 20 when the anode separator 30 and the cathode separator 40 try to move so that the distance between the anode separator 30 and the cathode separator 40 increases. In the present embodiment, the wall surface 51 is a side surface of a trapezoidal pyramid.

  In this embodiment, the cell forming step includes a step of arranging a pair of separators on both surfaces of the membrane-electrode assembly 10 having the sealing member 20 disposed on the outer periphery, and a step of pressing the pair of separators with the jig 500. , Including. The pair of separators are bonded to the membrane-electrode assembly 10 and the seal member 20 by being pressed. Moreover, the sealing member 20 is inject | poured into the recessed part 50 by pressing. That is, the cell forming process includes an arrangement process of arranging the seal member 20 in the recess 50. The pressing process is performed until the seal member 20 is cured. When the seal member 20 is cured, the jig 500 is removed from the fuel cell 100.

  FIG.1 (c) is typical sectional drawing which shows a lamination process. The stacking process is a process of manufacturing the stacked body 200 by stacking a plurality of fuel cells 100 manufactured in the cell forming process. Specifically, the plurality of fuel cells 100 are sequentially stacked such that the cathode separator 40 of another fuel cell 100 adjacent to the anode separator 30 of the fuel cell 100 is disposed. Thereby, the laminated body 200 is manufactured.

  FIG. 2 is a schematic cross-sectional view showing a stacking process. The stacking process is a process for manufacturing the fuel cell stack 300. Specifically, in the stacking step, a current collector (current collector 310 and current collector 311), an insulator (insulator 320 and insulator 321), and an end plate (end plate 330) are arranged at the end of the stack in the stacking direction. And a stacking step of sequentially stacking the end plates 331) and a fastening step of fastening these members with a fastening member 340.

  The current collector 310 is disposed at the end of the laminated body 200 on the anode side. The current collector 311 is disposed at the cathode side end of the multilayer body 200. The current collector 310 and the current collector 311 are electrically connected to a load such as a motor or an auxiliary machine. The current collector 310 and the current collector 311 are members for collecting the electric power generated by the power generation of each fuel cell 100 and taking it out.

  The insulator 320 is disposed on the opposite side of the current collector 310 from the stacked body 200. The insulator 321 is disposed on the side opposite to the stacked body 200 of the current collector 311. The insulator 320 and the insulator 321 are insulating members for electrically insulating the current collector and the end plate.

  The end plate 330 is disposed on the side of the insulator 320 opposite to the current collector 310. The end plate 331 is disposed on the side of the insulator 321 opposite to the current collector 311. As the fastening member 340, for example, a bolt or the like can be used. By being fastened by the fastening member 340, the end plates 330 and 331 apply a pressing force in the stacking direction to the stacked body 200, the current collectors 310 and 311, and the insulators 320 and 321.

  The fuel cell stack 300 operates as follows during power generation. First, the anode gas is supplied to the anode gas channel 31 of each fuel cell 100 and the cathode gas is supplied to the cathode gas channel 41. The anode gas flowing through the anode gas channel 31 diffuses through the anode gas diffusion layer 14 and reaches the anode catalyst layer 12. In the anode catalyst layer 12, hydrogen in the anode gas is separated into protons and electrons. Protons are conducted through the electrolyte membrane 11 and reach the cathode catalyst layer 13. The electrons are collected by the current collector 310 and taken out of the fuel cell stack 300. The electrons taken out of the fuel cell stack 300 reach the current collector 311 after being used for load work.

  The cathode gas flowing through the cathode gas flow channel 41 diffuses through the cathode gas diffusion layer 15 and reaches the cathode catalyst layer 13. In the cathode catalyst layer 13, water is generated by oxygen in the cathode gas, protons conducted through the electrolyte membrane 11, and electrons conducted from the current collector 311. The generated water mainly flows through the cathode gas channel 41 and is discharged to the outside of the fuel cell stack 300. The anode gas and cathode gas after the reaction flow through the anode gas channel 31 and the cathode gas channel 41, respectively, and are discharged to the outside of the fuel cell stack 300. As described above, the fuel cell stack 300 operates during power generation.

  Then, the effect of a present Example is demonstrated. FIG. 3A is a schematic cross-sectional view of a fuel cell 400 according to a comparative example. The separator of the fuel cell 400 does not have a portion corresponding to the recess 50. In the fuel cell 400, for example, when the pressing force applied from the jig 500 in the stacking process is loosened, the membrane-electrode assembly 10 may expand and deform. When the membrane-electrode assembly 10 is expanded and deformed, the fuel cell 400 is deformed as shown in FIG. Specifically, since the deformation amount of the cured seal member 20 and the deformation amount of the membrane-electrode assembly 10 are different, the fuel cell 400 is deformed so that the thickness of the central portion is larger than the thickness of the outer peripheral portion. In this case, the position of the separator may be shifted. As a result, the separator and the seal member 20 may be peeled off, resulting in a seal failure.

  On the other hand, according to the manufacturing method of the fuel cell stack 300 according to the present embodiment, as shown in FIG. 3B, the seal member 20 has a function as a positioning member for the pair of separators. . In this case, even when the external pressing force on the fuel cell 100 is relaxed after the cell forming step, the position shift of the separator can be suppressed. As a result, the occurrence of defective sealing can be suppressed. Further, since the positioning member is the seal member 20, the number of parts of the fuel cell stack 300 does not increase. In addition, since it is not necessary to newly provide a member such as a holding pin, the weight of the fuel cell stack 300 is suppressed. Furthermore, since the sealing member 20 continues to engage with the recess 50 even after the fuel cell stack 300 is manufactured, the position shift of the separator can be suppressed even after the fuel cell stack 300 is manufactured.

  Further, since the area of the opening of the recess 50 is smaller than the area of at least a part of the other part, when the fuel cell 100 is to be deformed so as to increase the distance between the pair of separators, the opening is disposed in the recess 50. The seal member 20 is caught in the opening. Thereby, since peeling with a separator and the sealing member 20 is suppressed, generation | occurrence | production of a sealing defect can be suppressed.

  Moreover, since the recessed part 50 has the wall surface 51, when the sealing member 20 arrange | positioned at the recessed part 50 gives a drag force to the wall surface 51, peeling with a separator and the sealing member 20 is suppressed. As a result, sealing failure can be suppressed.

  In addition, in a present Example, although the cell formation process includes the arrangement | positioning process (namely, process of inserting a positioning member) which arrange | positions the sealing member 20 in the recessed part 50, it is not restricted to this. The placement process of placing the seal member 20 in the recess 50 may be performed between the cell forming process and the end of the stacking process.

  Further, the number of separators may be two or more. For example, the separator may be disposed so as to further sandwich the anode separator 30 and the cathode separator 40.

(Modification 1)
In addition, the shape of the recessed part 50 is not restricted to the shape of Example 1. FIG. FIG. 4A to FIG. 4D are schematic cross-sectional views showing modifications of the recess 50. For example, as shown in FIG. 4A, the recess 50 may have an arcuate cross-sectional shape. Even in this case, the area of the opening is smaller than the area of at least a part of the other part (for example, the surface including the center point of the arc). Further, the recess 50 has a wall surface 51 (a wall surface on the membrane-electrode assembly 10 side from the center of the arc).

  As shown in FIG. 4B, the cross-sectional shape of the recess 50 may be a shape in which a small diameter portion and a large diameter portion are connected in order from the membrane-electrode assembly 10 side. Also in this case, the area of the opening is smaller than the area of at least a part of the other part (the inner diameter part of the large diameter part). Moreover, the recessed part 50 has the wall surface 51 (wall surface of the level | step-difference part of a large diameter part).

  Moreover, as shown in FIG.4 (c), the cross-sectional shape of the recessed part 50 may be a parallelogram. In this case, the wall surface 51 is a wall surface whose angle formed with the surface of the separator on the membrane-electrode assembly 10 side is smaller than 90 degrees.

  Moreover, as shown in FIG.4 (d), the cross-sectional shape of the recessed part 50 may be star shape. In this case, the area of the opening is smaller than the area of at least a part of the other part (for example, a surface parallel to the opening and including the vertex closest to the opening on the outer peripheral edge). The wall surface 51 is a wall surface having an angle of less than 90 degrees with the surface of the separator on the membrane-electrode assembly 10 side. Or the recessed part 50 may have various cross-sectional shapes, such as a wedge type | mold other than Fig.4 (a)-FIG.4 (d).

  Then, the manufacturing method of the fuel cell stack 300a which concerns on Example 2 is demonstrated. The method of manufacturing the fuel cell stack 300a includes a fuel cell according to the first embodiment in that the fuel cell 100a is manufactured in the cell forming step and a removal step of removing the positioning member after the fastening step of the stacking step. This is different from the manufacturing method of the stack 300.

  Fig.5 (a) is typical sectional drawing which shows the laminated body 200a after the fastening process of a stacking process. In the fuel cell 100a, instead of the seal member 20 being disposed in the recess 50, a rod-shaped member 60 is disposed. The rod-shaped member 60 functions as a positioning member for a pair of separators. The rod-shaped member 60 is inserted and disposed in the recess 50 in the cell forming process.

  FIG. 5B is a schematic cross-sectional view showing the removal process. In the removing step, the rod-shaped member 60 is removed by being pulled out from the recess 50. Thereby, the fuel cell stack 300a is manufactured. That is, the rod-shaped member 60 is a member that can be removed after the stacking process.

  Also in the manufacturing method of the fuel cell stack 300a according to the present embodiment, the rod-shaped member 60 can suppress the displacement of the separator. Thereby, generation | occurrence | production of the sealing defect can be suppressed. Further, since the rod-shaped member 60 is removed in the removing process, the number of parts of the fuel cell stack 300a does not increase. Further, the weight of the fuel cell stack 300a is suppressed. In addition, since the removal process is performed after the fastening process, the position shift of the separator is suppressed by the fastening member 340 after the rod-shaped member 60 is removed.

  In addition, it is preferable that the rod-shaped member 60 has the durability which can repeat insertion arrangement | positioning to the recessed part 50, and removal. In this case, the rod-shaped member 60 can be reused. Thereby, the manufacturing cost of the fuel cell stack 300a can be reduced.

DESCRIPTION OF SYMBOLS 10 Membrane-electrode assembly 11 Electrolyte membrane 12 Anode catalyst layer 13 Cathode catalyst layer 14 Anode gas diffusion layer 15 Cathode gas diffusion layer 20 Seal member 30 Anode separator 40 Cathode separator 50 Recess 51 Wall surface 60 Rod member 100 Fuel cell 200 Laminate 300 Fuel cell stack 310, 311 Current collector 320, 321 Insulator 330, 331 End plate 340 Fastening member 400 Fuel cell 500 Jig

Claims (5)

A cell forming step in which a pair of separators are disposed on both surfaces of a membrane-electrode assembly in which a seal member is disposed on the outer periphery;
A stacking step of stacking a plurality of fuel cells manufactured in the cell forming step;
A stacking step of fastening the stacked fuel cells with fastening members;
Inserting a positioning member that positions the pair of separators between at least the cell forming step and the end of the stacking step, and
The method of manufacturing a fuel cell stack, wherein the positioning member is the seal member or a member that can be removed after the stacking step.   The method for manufacturing a fuel cell stack according to claim 1, wherein the pair of separators have a recess in which the positioning member is disposed.   3. The method of manufacturing a fuel cell stack according to claim 2, wherein an area of the opening of the recess is smaller than an area of at least a part of another portion.   3. The method of manufacturing a fuel cell stack according to claim 2, wherein the recess has a wall surface that receives a drag force from the positioning member when the distance between the pair of separators increases.   The method for manufacturing a fuel cell stack according to claim 1, further comprising a removal step of removing the positioning member after the stacking step.

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