JP2010177009A - Cell of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration and degradation of strength in a power generating body 10 and a separator 20 caused by integrally molding a gasket 30, and deterioration of power generating efficiency, in a cell of a fuel cell in which the power generating body 10 is integrated with the separator 20 disposed on one side thereof through the gasket 30. <P>SOLUTION: This cell of the fuel cell includes the power generating body 10 formed by laminating and integrating gas diffusion layers 12, 13 on both sides in the thickness direction of a membrane electrode assembly 11 having electrode layers provided on both surfaces of an electrode membrane, a separator 20 disposed on one side of the power generating body 10, and the gasket 30 made of a rubber-like elastic material, which is disposed along the fringe part of the power generating body 10 and bonded to the separator 20 through an adhesive 34, and a locking portion 33 to lock the power generating body 10 to the separator 20 is formed in the gasket 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel in which a power generation body composed of a membrane-electrode assembly and a porous first gas diffusion layer laminated on both sides in the thickness direction thereof and a separator laminated thereon are integrated via a gasket. The present invention relates to a battery cell.

  FIG. 8 is a cross-sectional view showing a part of a fuel cell in which conventional fuel cells are stacked, and FIG. 9 is a cross-sectional view showing a part of a conventional fuel cell constituting the fuel cell of FIG.

  As shown in FIG. 8, the fuel cell has a stack structure in which a large number of fuel cells 100 are stacked and fastened. As shown in FIG. 9, each fuel battery cell 100 has a thickness direction of a membrane-electrode assembly (MEA) 111 in which a pair of electrode layers are provided on both surfaces of an electrolyte membrane (ion exchange membrane). On both sides, a power generation body 110 in which gas diffusion layers (GDL: Gas Diffusion Layer) 112 and 113 made of a porous material are laminated and integrated, and a separator 120 made of carbon or a conductive metal, which is arranged on one side, are laminated. Things are known.

  In this type of fuel cell, in each fuel cell 100, oxidizing gas (air) is supplied to the cathode side of the membrane-electrode assembly 111 through one of the gas diffusion layers 112 and 113 in the power generator 110. The fuel gas (hydrogen) is supplied to the anode side of the membrane-electrode assembly 111 through the other of the gas diffusion layers 112 and 113, and the reverse reaction of water electrolysis, that is, water is generated from hydrogen and oxygen. Electric power is generated by the reaction. Moreover, although the electromotive force of each fuel battery cell 100 is low, a required electromotive force can be obtained by stacking a large number of fuel battery cells 100 and electrically connecting them in series.

  A rubber-like elastic material (rubber-based material) is used to prevent fuel gas, oxidizing gas, water generated by the reaction, excess gas, etc. from leaking or mixing outside at the edge or opening edge of the power generator 110. Alternatively, a gasket 130 made of a synthetic resin material having rubber-like elasticity is disposed.

  The gasket 130 impregnates the edges (peripheral edge and opening edge) of the gas diffusion layers 112 and 113 in the power generator 110 with a part of a rubber-based or resin-based low-viscosity or liquid molding material during molding. The molding material is cured in a state where it is in contact with the separator 120 to which an adhesive has been applied in advance, so that it is integrally joined to the power generator 110 via the impregnation regions 112a and 113a formed in the gas diffusion layers 112 and 113. In addition, the separator 120 is also bonded and integrated. The gasket 130 has an angled main seal lip 130a as shown in FIG. 9, and this main seal lip 130a is crushed by the stacking load in the stacked state shown in FIG. By being in close contact with the separator 120, a required sealing function is achieved.

  In addition, what was disclosed by the following patent document is known as a technique which integrates a gasket to a gas diffusion layer and a separator through the impregnation region of a molding material.

  However, since the fuel cell 100 configured as described above has a structure in which the power generator 110 and the separator 120 are integrated via the gasket 130, the number of components is reduced and stacking deviation occurs. However, on the other hand, when the power generator 110 and the separator 120 are placed in the mold and the gasket 130 is integrally formed, the power generator 110 and the separator 120 may be mechanically damaged by clamping. There is a concern that the mold may be thermally damaged by heating. In particular, it is important to prevent thermal damage to the electrolyte membrane in the membrane-electrode assembly 111, which has a problem that the molding conditions are restricted.

  Further, when the gasket 130 is molded while impregnating a part of the molding material at the edges of the gas diffusion layers 112 and 113 made of a metal porous body or the like, the filling pressure or viscosity of the molding material is kept constant. However, since the porosity (porosity) of the gas diffusion layers 112 and 113 varies, it is difficult to appropriately control the size of the impregnation regions 112a and 113a of the molding material. As a result, when the impregnation regions 112a and 113a are too narrow, the bonding strength between the gasket 130 and the power generation body 110 is lowered and the sealing performance against gas permeation leakage is lowered. Conversely, when the impregnation regions 112a and 113a are too wide, As a result, the power generation region 110a (see FIG. 9) in the power generation body 110 is narrowed, resulting in a problem that power generation efficiency is lowered.

  Therefore, a method of limiting the impregnation of the molding material by forming protrusions on the inner surface of the mold and compressing part of the gas diffusion layers 112 and 113 with the protrusions at the time of clamping, A method of performing sealing treatment to limit the impregnation of the molding material to 112 and 113 is conceivable. However, in the former method, the gas diffusion layers 112 and 113 may be damaged by compression. A step of performing a sealing process on the diffusion layers 112 and 113 is required.

  Furthermore, in order to improve the drainage of water generated during the power generation process due to the reaction between hydrogen and oxygen, the surface of the separator 120 is required to have an appropriate wettability. There is a possibility that the gas generated during the sulfurization adversely affects the wettability of the surface of the separator 120.

JP 2002-160257 A

  The present invention has been made in view of the above points, and its technical problem is that a power generation body comprising a membrane-electrode composite and a gas diffusion layer and a separator disposed on one side thereof are gaskets. In the fuel cell united through the above, the strength of the power generator and the separator, the deterioration due to heat, and the decrease in power generation efficiency are prevented.

  As a means for effectively solving the technical problem described above, the fuel cell according to the present invention has a gas diffusion layer laminated on both sides in the thickness direction of a membrane-electrode composite in which electrode layers are provided on both sides of an electrolyte membrane. An integrated power generator, a separator disposed on one side of the power generator, and a rubber-like elastic material disposed along an edge of the power generator and bonded to the separator via an adhesive A gasket is provided, and a locking portion for locking the power generator to the separator is formed on the gasket.

  Here, “the edge of the power generator” is a general term for the outer peripheral edge and the opening edge of the power generator, and “rubber-like elastic material” is a rubber-based material or rubber-like elasticity. A synthetic resin material.

  Further, in the above configuration, more preferably, the locking portion is a seal surface that is brought into close contact with the membrane-electrode assembly exposed from the gas diffusion layer on the other side of the power generator with an appropriate surface pressure, and the fuel cell. In the laminated state, it has a sealing surface that is brought into close contact with a separator located on the other side of the power generator with an appropriate surface pressure.

  According to the fuel battery cell of the first aspect of the present invention, the power generator, the separator and the gasket can be integrally formed without integrally forming the gasket in the gas diffusion layer of the power generator by impregnation molding. For this reason, the power generation body composed of the membrane-electrode composite and the gas diffusion layer and the separator disposed on one side thereof are not likely to be adversely affected by heat reduction due to mold clamping during the integral molding of the gasket, or by heat, There is no risk of deterioration of the wettability of the separator, and power generation efficiency is not reduced due to the impregnation of the gasket molding material.

  According to the fuel cell of the invention of claim 2, in the stacked state of the fuel cell, the gasket is held in a state in which the engaging portion of the gasket is in intimate contact between the membrane-electrode assembly of the power generator and the separator. Since the structure covers the edge of the power generation body, it is possible to effectively block the reaction gas from flowing around the edge of the membrane-electrode assembly from the gas diffusion layer and cross leaking.

It is a fragmentary sectional view showing the fuel cell which laminated the fuel cell of the 1st form concerning the present invention. It is a fragmentary sectional view of the state before an assembly showing the fuel cell of the 1st form concerning the present invention. It is a fragmentary sectional view of the assembly state which shows the fuel cell of the 1st form which concerns on this invention. It is a fragmentary sectional view of the state before an assembly showing the fuel cell of the 2nd form concerning the present invention. It is a fragmentary sectional view of the assembly state which shows the fuel cell of the 2nd form which concerns on this invention. It is a fragmentary sectional view of the state before the assembly which shows the fuel cell of the 3rd form concerning the present invention. It is a fragmentary sectional view of the assembly state which shows the fuel cell of the 3rd form which concerns on this invention. It is a fragmentary sectional view which shows the fuel cell which laminated | stacked the conventional fuel cell. It is a fragmentary sectional view showing the conventional fuel cell.

  Hereinafter, a fuel cell according to the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a partial cross-sectional view showing a fuel cell in which fuel cells of the first embodiment are stacked, FIG. 2 is a partial cross-sectional view of a fuel cell of the first embodiment before assembly, and FIG. It is a fragmentary sectional view of the assembly state which shows the fuel cell of a 1st form.

  The fuel cell shown in FIG. 1 has a stack structure in which a large number of fuel cells 1 are stacked and fastened. As shown in FIG. 2, each fuel cell 1 includes a membrane-electrode assembly (MEA) 11 in which a pair of electrode layers (anode and cathode) are provided on both surfaces of an electrolyte membrane (ion exchange membrane). A power generation body 10 in which gas diffusion layers (GDL: Gas Diffusion Layer) 12 and 13 made of a metal porous body or the like are laminated and integrated on both sides in the thickness direction, and is disposed on one side thereof, and is made of carbon or conductive metal. And a gasket 30 made of a rubber-based material or a synthetic resin-based material having rubber-like elasticity, which is disposed along the edge of the power generator 10 and is bonded to the separator 20 via an adhesive 34. Prepare.

  The separator 20 is supplied with a reactive gas, that is, a fuel gas and an oxidizing gas, to the anode side and the cathode side of the membrane-electrode assembly 11 in the power generation body 10 or discharges water generated by an electrochemical reaction between the fuel gas and the oxidizing gas. Alternatively, a manifold hole is provided for supplying and discharging cooling water. The gas diffusion layers 12 and 13 in the power generation body 10 form a gas flow path for allowing the fuel gas and the oxidizing gas to flow between the supply-side manifold hole and the discharge-side manifold hole of the separator 20.

The power generation body 10 has a smaller area than the separator 20, that is, the edge located around the outer peripheral edge or manifold hole of the power generation body 10 is the edge of the separator 20 (outer peripheral edge or opening edge of the manifold hole). It is retracted by a certain width w ₁ from 20a.

The membrane-electrode assembly 11 and the gas diffusion layer 12 on one side of the power generation body 10 have the same area and the edges 11a and 12a are aligned with each other, whereas the gas diffusion layer 13 on the other side is The membrane-electrode assembly 11 and the gas diffusion layer 12 have a slightly smaller area, and the edge 13a located on the outer peripheral edge of the gas diffusion layer 13 on the other side or around the manifold hole is formed on the membrane-electrode assembly 11. and edge 11a of the gas diffusion layer 12, are retracted by a predetermined width w ₂ than 12a. For this reason, the edge of the power generation body 10 has a stepped shape, and the edge 11a of the membrane-electrode assembly 11 protrudes from the edge 13a of the gas diffusion layer 13 on the other side and is exposed.

  The gasket 30 is formed as a separate member from the power generation body 10 and the separator 20 by a mold (not shown), and extends along the edge of the power generation body 10 and is integrated with the separator 20 by bonding. Has been. The rubber-based material constituting the gasket 30 or the synthetic resin-based material having rubber-like elasticity is not particularly limited as long as it has less elution of components and has a required resistance in the use environment inside the fuel cell. For example, FKM (fluorine rubber), VMQ (silicone rubber), EPDM (ethylene propylene rubber), etc. can be suitably employed.

  The gasket 30 has a base 31 integrally bonded to one side of the separator 20 along the edge 20a via an adhesive 34, and a ridge formed in a cross-sectional mountain shape on the opposite side of the base 31 from the bonding surface. The main seal lip 32 is formed, and a locking portion 33 extending from the upper portion of the base portion 31 on the side of the power generator 10. Valley portions 31 a and 31 b extending along both sides of the main seal lip 32 are formed on the upper surface of the base portion 31 of the gasket 30.

The base portion 31 of the gasket 30 is formed by the edge portion 20a of the separator 20, the membrane-electrode assembly 11 of the power generation body 10 that is retracted by the width w ₁ and the edge portions 11a and 12a of the gas diffusion layer 12 on one side thereof. The height h ₁ is substantially equal to the thickness t of the power generation body 10, and the height h ₂ of the main seal lip 32 is appropriately larger than the thickness t of the power generation body 10. The locking portion 33 has a size that can be accommodated in a stepped portion formed by the edge portion 11a of the membrane-electrode assembly 11 in the power generator 10 and the edge portion 13a of the gas diffusion layer 13 on the other side that is retracted by a width w ₂ from the edge portion 11a. ing.

  In addition, the locking portion 33 has a bead-shaped sealing surface that is brought into close contact with the edge portion 11a of the membrane-electrode assembly 11 of the power generation body 10 in the stacked state of the fuel cell 1 shown in FIG. 33a and a flat sealing surface 33b that is in close contact with the separator 20 of the adjacent fuel cell 1 are formed.

  According to the first embodiment having the above configuration, the gasket 30 is molded as a separate member from the power generation body 10 and the separator 20. For this reason, unlike impregnation molding as described above, there are no restrictions such as the viscosity of rubber-based or resin-based molding materials to be used, the degree of freedom in material selection can be increased, and the vulcanization of molding materials can be increased. There is no possibility that the gas generated at this time adversely affects the wettability of the surface of the separator 20 and the gas diffusion layers 12 and 13. Moreover, since it is not necessary to consider the heat resistance of the membrane-electrode assembly 11 in the power generation body 10, it is possible to perform molding in a short time by setting the molding temperature during vulcanization to a high temperature (for example, 150 ° C. or higher). Thus, productivity can be improved.

  Further, unlike the impregnation molding as described above, it is not necessary to preliminarily perform sealing treatment by pre-impregnation of the molding material on the gas diffusion layers 12 and 13, so that the number of processes does not increase and the gas diffusion does not occur. The layers 12 and 13 do not receive an extra heat history for vulcanization of the sealing portion, and the gas diffusion layers 12 and 13 do not receive mechanical damage due to mold clamping.

  When the fuel cell 1 is assembled, first, the power generator 10 is positioned and placed on the separator 20 from the state before assembly shown in FIG. Next, an adhesive 34 shown by a broken line is applied to the surface of the base portion 31 of the gasket 30 opposite to the main seal lip 32, and the base portion 31 of the edge portion 20a of the separator 20 protruding from the edge portion of the power generator 10 is applied. Adhere to the upper surface 20b. At this time, the load necessary to bond the gasket 30 to the separator 20 may be sufficiently smaller than the clamping pressure for integrally molding the gasket 30 to the separator 20, so that the separator 20 may be deformed. There is no. Moreover, there is no restriction | limiting in particular as a material of the adhesive agent 34, For example, adhesive agents, such as a rubber paste type | system | group and an epoxy type, can be employ | adopted suitably.

  Then, as described above, the base portion 31 of the gasket 30 is bonded to the separator 20, whereby the bead-shaped sealing surface 33 a of the locking portion 33 extending from the base portion 31 becomes the membrane-electrode assembly 11 of the power generator 10. Since the power generator 10 is in contact with the edge portion 11a of the membrane-electrode assembly 11, the edge portion 11a of the membrane-electrode assembly 11 and the edge portion 12a of the gas diffusion layer 12 on one side thereof are located between the separator 20 and the engaging portion 33. The fuel cell 1 is obtained in which the power generator 10 and the separator 20 are integrated with each other through the gasket 30 as shown in FIG.

  As shown in FIG. 1, the fuel cells 1 assembled in this way are assembled as a fuel cell stack by stacking a large number in the thickness direction and electrically connecting them in series.

  In this fuel cell stack, in each fuel cell 1, oxidizing gas (air) is supplied to the cathode side of the membrane-electrode assembly 11 via one of the gas diffusion layers 12 and 13 in the power generator 10. Fuel gas (hydrogen) is supplied to the anode side of the membrane-electrode assembly 11 through the other of the gas diffusion layers 12 and 13 in the power generation body 10, and reverse reaction of water electrolysis, that is, water from hydrogen and oxygen. The electric power is generated by the electrochemical reaction that generates the electric power, and this electric power is taken out through the separator 20 that is a current collector plate.

  Here, the gasket 30 of each fuel battery cell 1 is brought into close contact with the edge 20a of the separator 20 in another adjacent fuel battery cell 1 in a state where the main seal lip 32 is appropriately crushed. It has a sealing function to prevent the oxidant gas, fuel gas, etc. flowing in the flow path by the manifold holes and the gas diffusion layers 12 and 13 from leaking. Since the stress due to compression of the main seal lip 32 is absorbed to some extent by the valley portions 31a and 31b on both sides, it is possible to suppress deterioration in sealing performance over time due to the settling of the main seal lip 32.

  Further, in the stacked state of the fuel cells 1 shown in FIG. 1, the engaging portion 33 in each gasket 30 is the exposed edge portion 11 a of the membrane-electrode assembly 11 of the power generator 10 and the separator of the adjacent fuel cell 1. 20, the sealing surfaces 33 a and 33 b are in close contact with each other, and the locking portion 33 and the base portion 31 allow the edge of the power generator 10, that is, the edge of the membrane-electrode assembly 11 and the gas diffusion layers 12 and 13. Since the portions 11a, 12a, and 13a are shielded, the oxidizing gas and the fuel gas are transferred from the edge portion 12a of the gas diffusion layer 12 on one side and the edge portion 13a of the gas diffusion layer 13 on the other side. It is possible to effectively prevent cross-leakage between the two edges 11a.

  Furthermore, according to this fuel cell 1, since the gas diffusion layers 12 and 13 of the power generation body 10 do not have a conventional impregnation region of the molding material, as shown in FIG. The entire region surrounded by the bead-shaped sealing surface 33a of the portion 33 can be used as the power generation region 10a. Therefore, it is possible to secure a wide power generation region 10a and improve power generation efficiency.

  Next, FIG. 4 is a partial cross-sectional view of a state before assembly showing a fuel cell of the second embodiment according to the present invention, and FIG. 5 is a partial cross-sectional view of an assembled state showing the fuel cell of the second embodiment. It is.

  In the fuel cell 1 of the second embodiment, the difference from the first embodiment described above is that the facing portion 33 of the gasket 30 faces away from the membrane-electrode assembly 11 of the power generator 10. The seal surface 33b is formed in a kamaboko-shaped convex surface that is raised higher than the upper surface of the power generator 10 (the upper surface of the gas diffusion layer 13 on the other side). Other parts are basically configured in the same manner as in the first embodiment.

  The fuel cell 1 according to this embodiment basically has the same effect as that of the first embodiment. In the stacked state as shown in FIG. 1, the engaging portion 33 of the gasket 30 has the bead-shaped sealing surface 33 a in close contact with the edge portion 11 a of the membrane-electrode assembly 11 of the power generator 10 with an appropriate crushing allowance. At the same time, the convex seal surface 33b on the opposite side is brought into intimate contact with the separator 20 of the adjacent fuel cell 1 with an appropriate crushing allowance. For this reason, even if the bead-shaped sealing surface 33a is settling, the entire surface 33c on the side of the bead-shaped sealing surface 33a is the membrane-electrode assembly by the compression reaction force of the convex sealing surface 33b. 11 will be in close contact with the edge 11a, and good sealing performance will be maintained.

  Next, FIG. 6 is a partial cross-sectional view of the fuel cell of the third embodiment according to the present invention before assembly, and FIG. 7 is a partial cross-sectional view of the assembled state of the fuel cell of the third embodiment. It is.

  In the fuel cell 1 of the third embodiment, the difference from the first embodiment described above is that the seal that is in close contact with the membrane-electrode assembly 11 of the power generator 10 among the engaging portions 33 of the gasket 30. The surface 33a is formed flat, and the seal surface 33b on the opposite side is formed in a kamaboko-shaped convex surface that is raised higher than the upper surface of the power generator 10 (the upper surface of the gas diffusion layer 13 on the other side). Other parts are basically configured in the same manner as in the first embodiment.

  The fuel cell 1 according to this embodiment basically has the same effect as that of the first embodiment. In the stacked state as shown in FIG. 1, the locking portion 33 of the gasket 30 has a flat sealing surface 33 a in close contact with the edge portion 11 a of the membrane-electrode assembly 11 of the power generator 10 with an appropriate surface pressure. At the same time, the convex seal surface 33b on the opposite side is brought into intimate contact with the separator 20 of the adjacent fuel cell 1 with an appropriate crushing allowance. For this reason, since the gap between the edge portion 11a of the membrane-electrode assembly 11 of the power generator 10 and the separator 20 facing the edge portion 11a is filled with the engaging portion 33 of the gasket 30, a good sealing is achieved. Sex is maintained.

DESCRIPTION OF SYMBOLS 1 Fuel cell 10 Electric power generation body 11 Membrane-electrode assembly 11a, 12a, 13a, 20a Edge part 12, 13 Gas diffusion layer 20 Separator 30 Gasket 31 Base part 31a, 31b Valley part 32 Main seal lip 33 Locking part 33a, 33b Seal surface 34 Adhesive

Claims (2)

  A power generation body in which gas diffusion layers are laminated and integrated on both sides in the thickness direction of a membrane-electrode assembly in which electrode layers are provided on both surfaces of the electrolyte membrane, a separator disposed on one side of the power generation body, And a gasket made of a rubber-like elastic material that is disposed along the edge and is bonded to the separator via an adhesive, and a locking portion for locking the power generator to the separator is formed on the gasket. A fuel battery cell characterized by that.   The engaging portion has a seal surface that is intimately contacted with the membrane-electrode assembly exposed from the gas diffusion layer on the other side of the power generator with an appropriate surface pressure, and the other side of the power generator in the stacked state of the fuel cell. 2. The fuel cell according to claim 1, further comprising a sealing surface that is brought into close contact with the separator located at an appropriate surface pressure. 3.

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