JP3866246B2 - Fuel cell - Google Patents

Description

The present invention includes an electrolyte membrane / electrode structure in which a first electrode and a second electrode having a larger surface area than the first electrode are disposed on both sides of the electrolyte membrane, and the electrolyte membrane / electrode structure is a first electrode. and the power generation cell disposed between the second metal separator about the fuel cells to be stacked.

  For example, a polymer electrolyte fuel cell has an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are provided on both sides of an electrolyte membrane made of a polymer ion exchange membrane (cation exchange membrane). A power generation cell sandwiched between separators is provided. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of power generation cells.

  In this power generation cell, the fuel gas supplied to the anode side electrode, for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas) is ionized with hydrogen on the electrode catalyst, and the cathode passes through the electrolyte membrane. Move to the side electrode side. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy. The cathode side electrode is supplied with an oxidant gas, for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas). And oxygen reacts to produce water.

  In the power generation cell described above, various seal structures are employed in order to keep the fuel gas, the oxidant gas, and the cooling medium airtight and liquid tight. For example, a fuel cell disclosed in Patent Document 1 includes a power generation cell 4 in which an electrolyte membrane / electrode assembly 1 is sandwiched between first and second separators 2 and 3 as shown in FIG. A fuel cell stack is configured by stacking a plurality of 4.

  A first seal member 5 is provided to cover the front and back of the outer peripheral portion of the first separator 2, and a second seal member 6 is provided to cover the front and back of the outer peripheral portion of the second separator 3.

  The first seal member 5 includes a flat seal 5a provided on one surface of the first separator 2, a flat seal 5b provided on the other surface of the first separator 2, and a thick seal continuous with the flat seal 5b. 5c. The second seal member 6 includes an outer convex seal 6a and a thick seal 6b provided on one surface of the second separator 3, and an outer convex seal 6c and an inner convex provided on the other surface of the second separator 3. 6d.

  In the power generation cell 4, the planar seal 5 b and the thick seal 5 c of the first seal member 5 are in close contact with the outer convex seal 6 c and the inner convex seal 6 d of the second seal member 6. Further, between the power generation cells 4, the outer convex seal 6 a and the thick seal 6 b of the second seal member 6 are in close contact with the flat seal 5 a of the first seal member 5.

JP 2002-305006 A (paragraphs [0110] to [0111], FIG. 19)

  Meanwhile, the first seal member 5 is provided with the planar seals 5a and 5b and the thick seal 5c, and the second seal member 6 is provided with the outer convex seals 6a and 6c, the thick seal 6b and the inner convex seal 6d. Is provided. For this reason, the configuration of the first and second seal members 5 and 6 is considerably complicated, and the manufacturing cost of the first and second seal members 5 and 6 may increase.

  Moreover, the first and second seal members 5 and 6 have different front and back seal structures. Therefore, for example, when the first and second seal members 5 and 6 are integrally formed with the first and second separators 2 and 3 made of metal, the first and second separators 2 are caused by uneven injection pressure for molding. 3 may be deformed.

  Furthermore, recently, an electrolyte membrane / electrode structure (hereinafter also simply referred to as a step MEA) in which a first electrode and a second electrode having a larger surface area than the first electrode are disposed on both sides of the electrolyte membrane has been used. However, in the above-mentioned Patent Document 1, it cannot be applied directly to this type of step MEA.

  The present invention solves this type of problem, and is a fuel cell capable of reliably preventing deformation of a metal separator and ensuring a desired sealing function of a step MEA with a simple and economical configuration. The purpose is to provide.

  The present invention includes an electrolyte membrane / electrode structure in which a first electrode and a second electrode having a larger surface area than the first electrode are disposed on both sides of the electrolyte membrane, and the electrolyte membrane / electrode structure is a first electrode. And a plurality of power generation cells disposed between the second metal separators. A first seal member is integrally provided on both surfaces of the first metal separator so as to cover the outer periphery of the first metal separator, and a second seal member is provided on both surfaces of the second metal separator so as to cover the outer periphery of the second metal separator. Are provided integrally.

  The first seal member is provided on one surface of the first metal separator facing the first electrode, and contacts the outer peripheral edge of the electrolyte membrane / electrode structure protruding outward from the outer periphery of the first electrode. A first inner convex seal that circulates, a first outer convex seal that is provided on the one surface and circulates around the outer periphery of the electrolyte membrane / electrode structure, and the other opposite to the one surface A second inner convex seal provided on a surface and disposed at substantially the same position as the first inner convex seal, and provided on the other surface and disposed at substantially the same position as the first outer convex seal. And a second outer convex seal.

  The second seal member is provided on one surface of the second metal separator facing the second electrode, the first flat seal contacting the first outer convex seal of the first seal member, and the one surface A second planar seal that contacts the second inner convex seal and the second outer convex seal of the first seal member that is provided on the other opposite surface and constitutes another power generation cell.

  In addition, a first seal member is integrally formed in a frame shape on both surfaces of the first metal separator so as to cover the outer periphery, and a second seal member is formed in a frame shape so as to cover the outer periphery on both surfaces of the second metal separator. It is preferable to be integrally formed.

  Furthermore, the fuel gas supply communication hole, the oxidant gas supply communication hole, the cooling medium supply communication hole, the fuel gas discharge communication hole, the oxidation gas and the electrode structure and the first and second metal separators are penetrated in the stacking direction. Six communication holes, a reagent gas discharge communication hole and a cooling medium discharge communication hole, are provided, and on the both sides of the first and second metal separators, the six communication holes are provided at portions where frame-shaped seal members are provided. It is preferable that three of them are distributed and formed. That is, the insulation of the first and second metal separators can be ensured by covering the inside of the communication hole with the seal member.

  In the present invention, on both surfaces of the first seal member, the first inner convex seal and the second inner convex seal are disposed at substantially the same position, and the first outer convex seal and the second outer convex seal are Are arranged at substantially the same position. Therefore, when the first seal member is integrally formed with the first metal separator, deviation of the injection pressure for molding, etc. can be avoided, and deformation of the first metal separator can be effectively reduced.

  Furthermore, only the first and second flat seals are provided on both surfaces of the second seal member, and the second seal member is formed economically and easily. In addition, when the second seal member is formed on the second metal separator, it is possible to satisfactorily prevent the second metal separator from being deformed.

  Furthermore, the first seal member is provided with the first and second inner convex seals and the first and second outer convex seals, whereas the second seal member is not provided with the convex seal. . As a result, the first metal separator and the second metal separator can be easily and reliably identified, and parts management and fuel cell assembly work can be simplified at once, and workability can be improved.

  In addition, since the convex seal of the first seal member contacts the flat seal of the second seal member, it is not necessary to accurately position the convex seal, and the assembly operation of the fuel cell is facilitated.

  In the present invention, the first and second convex seals are provided on both surfaces of the first metal separator at substantially the same position, and the first and second convex seals function as reinforcing ribs. For this reason, when the thickness of the first metal separator is reduced, the first metal separator is not deformed, and the power generation performance stability, sealing performance, and insulation properties are ensured by uniformity of the surface pressure distribution. It becomes possible to do.

  FIG. 1 is an exploded perspective view of a main part of a power generation cell 12 constituting a fuel cell 10 according to an embodiment of the present invention, and FIG. FIG. 2 is a sectional view of the fuel cell 10 taken along the line II-II in FIG.

  In the fuel cell 10, a plurality of power generation cells 12 are stacked in the direction of arrow A, and end plates 14a and 14b are disposed at both ends in the stacking direction (see FIG. 2). The end plates 14a and 14b are fixed via tie rods (not shown), whereby a predetermined tightening load is applied to the stacked power generation cells 12 in the arrow A direction.

  As shown in FIG. 1, the power generation cell 12 includes an electrolyte membrane / electrode structure 16 sandwiched between first and second metal separators 18 and 20. The first and second metal separators 18 and 20 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate whose surface is subjected to anticorrosion treatment. The thickness of the 1st and 2nd metal separators 18 and 20 is set in the range of 0.05 mm-1.0 mm, for example.

  The electrolyte membrane / electrode structure 16 includes, for example, a solid polymer electrolyte membrane 22 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode (first electrode) 24 sandwiching the solid polymer electrolyte membrane 22. And a cathode side electrode (second electrode) 26. The anode side electrode 24 has a smaller surface area than the cathode side electrode 26.

  The anode side electrode 24 and the cathode side electrode 26 include a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles having a platinum alloy supported on the surface are uniformly applied to the surface of the gas diffusion layer. And have. The electrode catalyst layer is bonded to both surfaces of the solid polymer electrolyte membrane 22.

  One end edge of the power generation cell 12 in the direction of arrow B (the horizontal direction in FIG. 1) communicates with each other in the direction of arrow A, which is the stacking direction, and oxidant for supplying an oxidant gas, eg, an oxygen-containing gas An agent gas inlet communication hole 30a, a cooling medium outlet communication hole 32b for discharging a cooling medium, and a fuel gas outlet communication hole 34b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided in the direction of arrow C (vertical direction). Are provided in an array.

  The other end edge of the power generation cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas inlet communication hole 34a for supplying fuel gas, and a cooling medium inlet communication hole for supplying a cooling medium. 32a and oxidant gas outlet communication holes 30b for discharging the oxidant gas are arranged in the direction of arrow C.

  As shown in FIG. 3, the surface 18a of the first metal separator 18 facing the electrolyte membrane / electrode structure 16 communicates with a fuel gas inlet communication hole 34a and a fuel gas outlet communication hole 34b, as will be described later. For example, a fuel gas flow path 36 that extends vertically downward while meandering in the direction of arrow B is provided.

  As shown in FIG. 1, the surface 20a of the second metal separator 20 facing the electrolyte membrane / electrode structure 16 communicates with an oxidant gas inlet communication hole 30a and an oxidant gas outlet communication hole 30b, and is in the direction of arrow B. The oxidant gas flow path 38 extending in the vertical upward direction (arrow C direction) while meandering is formed. As shown in FIGS. 1 and 2, the surface 18b of the first metal separator 18 and the surface 20b of the second metal separator 20 communicate with the cooling medium inlet communication hole 32a and the cooling medium outlet communication hole 32b. A cooling medium flow path 40 is formed. The cooling medium flow path 40 extends linearly in the direction of arrow B.

  The first seal member 42 is integrated with the surfaces 18a and 18b of the first metal separator 18 in a frame shape around the outer peripheral end of the first metal separator 18 by injection molding or the like. The first seal member 42 uses, for example, a seal material such as EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, a cushion material, or a packing material. To do. The thickness of the first seal member 42 is set within a range of 0.05 mm to 2 mm, for example.

  As shown in FIG. 2, the first seal member 42 includes a first outer convex seal 44a provided on the surface 18a adjacent to the outer peripheral end of the first metal separator 18, and the first outer convex seal 44a. A first inner convex seal 46a is provided at a predetermined distance from the inside. The first outer convex seal 44 a goes around the outer periphery of the electrolyte membrane / electrode structure 16, and the first inner convex seal 46 a goes around the outer periphery of the anode side electrode 24.

  As shown in FIG. 3, the first outer convex seal 44a includes the oxidant gas inlet communication hole 30a, the cooling medium outlet communication hole 32b, the fuel gas outlet communication hole 34b, the fuel gas inlet communication hole 34a, and the cooling medium inlet communication hole. 32a and the oxidizing gas outlet communication hole 30b are surrounded. The first inner convex seal 46a surrounds the fuel gas flow path 36, and the outer periphery of the electrolyte membrane / electrode structure 16 is interposed between the first inner convex seal 46a and the first outer convex seal 44a. Ends are arranged (see FIG. 2).

  The first seal member 42 includes a second outer convex seal 44b provided on the surface 18b close to the outer peripheral end of the first metal separator 18, and a predetermined distance inward from the second outer convex seal 44b. A second inner convex seal 46b is provided at a distance (see FIG. 2). As shown in FIG. 3, the second outer convex seal 44b includes an oxidant gas inlet communication hole 30a, a cooling medium outlet communication hole 32b, a fuel gas outlet communication hole 34b, a fuel gas inlet communication hole 34a, and a cooling medium inlet communication hole. 32a and the oxidizing gas outlet communication hole 30b are surrounded. The second inner convex seal 46 b surrounds the cooling medium flow path 40 and communicates the cooling medium inlet communication hole 32 a and the cooling medium outlet communication hole 32 b with the cooling medium flow path 40.

  As shown in FIG. 2, the first and second outer convex seals 44a and 44b are set at substantially the same position across the first metal separator 18, and the first and second inner convex seals 46a and 46b. Are set at substantially the same position across the first metal separator 18.

  On the surfaces 20a and 20b of the second metal separator 20, the second seal member 50 is integrated in a frame shape by injection molding or the like around the outer peripheral end of the second metal separator 20. The second seal member 50 may be made of the same material as the first seal member 42 or may be made of a different material. The thickness of the second seal member 50 is set within a range of 0.05 mm to 2 mm, for example.

  The second seal member 50 includes a first flat seal 52 that is integrated with the surface 20 a of the second metal separator 20, and a second flat seal 54 that is integrated with the surface 20 b of the second metal separator 20. As shown in FIG. 1, the first flat seal 52 is formed so as to surround the oxidant gas inlet communication hole 30 a and the oxidant gas outlet communication hole 30 b so as to communicate with the oxidant gas flow path 38. The The second flat seal 54 is formed by communicating the cooling medium inlet communication hole 32 a and the cooling medium outlet communication hole 32 b with the cooling medium flow path 40.

  As shown in FIG. 2, the first flat seal 52 is configured to be shorter than the second flat seal 54. The first outer convex seal 44 a of the first seal member 42 contacts the first flat seal 52 of the second seal member 50, and the first inner convex seal 46 a is the solid polymer electrolyte of the electrolyte membrane / electrode structure 16. It directly contacts the outer peripheral edge of the membrane 22. When the solid polymer electrolyte membrane 22 is configured to have the same dimensions as the anode-side electrode 24, the outer peripheral edge portion of the cathode-side electrode 26 is impregnated with a sealing material, and the first inner convex shape is formed on the outer peripheral edge portion. The seal 46a may be brought into direct contact.

  The second outer convex seal 44b and the second inner convex seal 46b of the first seal member 42 are the second plane of the second seal member 50 integrated with the second metal separator 20 constituting another power generation cell 12. Contact seal 54.

  As shown in FIGS. 1 and 3, the first metal separator 18 has a plurality of passages communicating with the surface 18b provided with the cooling medium flow path 40, respectively, with the fuel gas inlet communication hole 34a and the fuel gas outlet communication hole 34b. 56a and 56b are formed. The passages 56a and 56b communicate with a plurality of holes 58a and 58b, and the holes 58a and 58b communicate with a fuel gas flow path 36 provided on the surface 18a.

  The oxidant gas inlet communication hole 30a, the cooling medium outlet communication hole 32b, the fuel gas outlet communication hole 34b, the fuel gas inlet communication hole 34a, the cooling medium inlet communication hole 32a, and the oxidant gas outlet communication hole 30b are first and second. It is formed in the site | part which provided the frame-shaped seal | sticker of the sealing members 42 and 50, each inner side is covered with the seal | sticker, and the insulation of the 1st and 2nd metal separators 18 and 20 is ensured.

  The operation of the fuel cell 10 configured as described above will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 34a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 32a.

  For this reason, the oxidant gas is introduced into the oxidant gas flow path 38 of the second metal separator 20 from the oxidant gas inlet communication hole 30a and moves vertically downward while meandering in the arrow B direction. Therefore, the oxidant gas is supplied to the cathode-side electrode 26 constituting the electrolyte membrane / electrode structure 16. On the other hand, the fuel gas is introduced into the fuel gas flow path 36 of the first metal separator 18 from the fuel gas inlet communication hole 34a through the passage 56a and the hole 58a (see FIG. 3). This fuel gas moves vertically downward while meandering in the direction of arrow B, and is supplied to the anode side electrode 24 constituting the electrolyte membrane / electrode structure 16.

  Therefore, in each electrolyte membrane / electrode structure 16, the oxidant gas supplied to the cathode side electrode 26 and the fuel gas supplied to the anode side electrode 24 are consumed by an electrochemical reaction in the electrode catalyst layer. Power generation is performed.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 26 is discharged in the direction of arrow A along the oxidant gas outlet communication hole 30b (see FIG. 1). The fuel gas consumed by being supplied to the anode side electrode 24 passes through the hole 58b and the passage 56b and is discharged in the direction of arrow A along the fuel gas outlet communication hole 34b.

  The cooling medium supplied to the cooling medium inlet communication hole 32a is introduced into the cooling medium flow path 40 between the first and second metal separators 18 and 20, and then flows in the arrow B direction. The cooling medium is discharged from the cooling medium outlet communication hole 32b after the electrolyte membrane / electrode structure 16 is cooled.

  In this case, in the present embodiment, as shown in FIG. 2, the first seal member 42 is integrated around the outer peripheral end portion of the first metal separator 18. The first seal member 42 has a first inner convex seal 46a and a first outer convex seal 44a on one surface, and a second inner convex seal 46b and a second outer convex seal 44b on the other surface. have.

  The first inner convex seal 46a and the second inner convex seal 46b are disposed at substantially the same position on both surfaces of the first metal separator 18, and the first outer convex seal 44a and the second outer convex seal are disposed. The seal 44b is disposed at substantially the same position. Therefore, when the first seal member 42 is integrally formed with the first metal separator 18, an uneven injection pressure for molding is avoided, and the deformation of the first metal separator 18 can be effectively reduced. can get.

  At this time, the first metal separator 18 is injection-molded in a state where the first metal separator 18 is corrected by a mold (not shown), so that the undulation and warpage of the first metal separator 18 can be corrected well. Is possible.

  Moreover, the first seal member 42 has first and second inner convex seals 46a and 46b and first and second outer convex seals 44a and 44b, which function as reinforcing ribs. For this reason, even if the first metal separator 18 is thinned, the first metal separator 18 is not deformed, and the stability of the power generation performance, the sealing performance, and the insulation are ensured by the uniform surface pressure distribution. be able to. Note that the second metal separator 20 and the second seal member 50 also have the same effect as described above.

  On the other hand, the second seal member 50 includes a first flat seal 52 that contacts the first outer convex seal 44 a of the first seal member 42 and a second inner convex of the first seal member 42 that constitutes another power generation cell 12. And a second flat seal 54 in contact with the second seal 46b and the second outer convex seal 44b.

  For this reason, only the first and second flat seals 52 and 54 are provided on both surfaces of the second seal member 50, and the second seal member 50 is formed economically and easily. In addition, when the second seal member 50 is formed on the second metal separator 20, there is an advantage that it is possible to satisfactorily prevent the second metal separator 20 from being deformed.

  Moreover, the thickness of the 1st and 2nd sealing members 42 and 50 is set in the range of 0.05 mm-2 mm, for example. Therefore, even if the first and second metal separators 18 and 20 are warped or undulated, the outer peripheral ends of the first and second metal separators 18 and 20 are separated from the first and second seal members 42 and 50. It is possible to prevent the surface pressure distribution from becoming nonuniform while ensuring desired insulation without being exposed to the outside.

  Further, the first seal member 42 is provided with first and second inner convex seals 46a, 46b and first and second outer convex seals 44a, 44b, while the second seal member 50 is provided with a convex. No seal is provided. Thereby, the 1st metal separator 18 and the 2nd metal separator 20 can be identified easily and reliably, parts management and the assembly operation of a fuel cell are simplified at once, and workability | operativity is achieved.

It is a principal part disassembled perspective explanatory view of the power generation cell which constitutes the fuel cell concerning the embodiment of the present invention. FIG. 2 is a sectional view of the fuel cell taken along line II-II in FIG. 1. It is front explanatory drawing of the 1st metal separator which comprises the said electric power generation cell. 2 is an explanatory diagram of a fuel cell disclosed in Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Power generation cell 16 ... Electrolyte membrane and electrode structure 18, 20 ... Metal separator 22 ... Solid polymer electrolyte membrane 24 ... Anode side electrode 26 ... Cathode side electrode 30a ... Oxidant gas inlet communication hole 30b ... Oxidation Agent gas outlet communication hole 32a ... Cooling medium inlet communication hole 32b ... Cooling medium outlet communication hole 34a ... Fuel gas inlet communication hole 34b ... Fuel gas outlet communication hole 36 ... Fuel gas flow path 38 ... Oxidant gas flow path 40 ... Cooling medium Flow path 42, 50 ... Seal member 44a, 44b ... Outer convex seal 46a, 46b ... Inner convex seal 52, 54 ... Flat seal 56a, 56b ... Passage 58a, 58b ... Hole

Claims (3)

An electrolyte membrane / electrode structure having a first electrode and a second electrode having a larger surface area than the first electrode on both sides of the electrolyte membrane, the electrolyte membrane / electrode structure being a first and a second metal A fuel cell in which a plurality of power generation cells disposed between separators are stacked,
A first seal member that covers the outer periphery of the first metal separator and is integrally provided on both surfaces of the first metal separator;
A second seal member that covers the outer periphery of the second metal separator and is integrally provided on both surfaces of the second metal separator;
With
The first seal member is provided on one surface of the first metal separator facing the first electrode, and protrudes outward from the outer periphery of the first electrode. The outer peripheral edge of the electrolyte membrane / electrode structure A first inner convex seal that circulates in contact with
A first outer convex seal provided on the one surface and orbiting the outer periphery of the electrolyte membrane / electrode structure;
A second inner convex seal provided on the other surface opposite to the one surface and disposed substantially at the same position as the first inner convex seal;
A second outer convex seal provided on the other surface and disposed at substantially the same position as the first outer convex seal;
Have
The second seal member is provided on one surface of the second metal separator facing the second electrode, and a first flat seal that contacts the first outer convex seal;
A second flat seal provided on the other surface opposite to the one surface and contacting the second inner convex seal and the second outer convex seal of the first seal member constituting another power generation cell. When,
A fuel cell comprising: 2. The fuel cell according to claim 1, wherein the first seal member is integrally formed in a frame shape on both sides of the first metal separator so as to cover an outer periphery,
The fuel cell, wherein the second seal member is integrally formed in a frame shape on both surfaces of the second metal separator so as to cover an outer periphery. 3. The fuel cell according to claim 1, wherein a fuel gas supply communication hole, an oxidant gas supply communication hole, and a cooling medium penetrate through the electrolyte membrane / electrode structure and the first and second metal separators in the stacking direction. There are provided six communication holes including a supply communication hole, a fuel gas discharge communication hole, an oxidant gas discharge communication hole, and a cooling medium discharge communication hole,
6. The fuel cell according to claim 6, wherein six communication holes are distributed and formed on both sides of the first and second metal separators at portions where frame-shaped seal members are provided.

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