JP2009043492A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to alleviate a load difference between a power-generating part and a sealing part of the metal separator, prevent cracks of a metal plate as much as possible, and maintain a good sealing property. <P>SOLUTION: An oxidant gas flow channel 30 as a power generating part opposed to a cathode side electrode 26 and a flow channel sealing part 36a surrounding the oxidant gas flow channel 30 are provided on a face 14a of a first metal separator 14 constituting the fuel cell 10. A deforming part 40 more easily deformable than other parts when an outside load is imparted is provided between the oxidant gas flow channel 30 and the flow channel sealing part 36a, and at the same time, the deforming part 40 is provided with a bead-shaped part 42 extended along a length direction of the flow channel sealing part 36a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte and a metal separator provided integrally with a seal member are laminated.

  For example, a polymer electrolyte fuel cell includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) in which an anode side electrode and a cathode side electrode are disposed on both sides of a solid polymer electrolyte membrane (MEA) made of a polymer ion exchange membrane. The electrode structure is sandwiched between separators. In this type of fuel cell, when used for in-vehicle use, a fuel cell stack is usually formed by stacking several tens to several hundreds of fuel cells.

  In this case, as the separator, in addition to the carbon separator, a metal separator in which a sealing member is integrally formed on a thin metal plate is used. This type of metal separator is manufactured, for example, by a method for manufacturing a silicone resin-metal composite disclosed in Patent Document 1.

  Specifically, as shown in FIG. 6, the end of the thin metal plate 1 is placed in a mold cavity formed on the mating surface of the fixed side mold plate 2a and the movable side mold plate 2b constituting the mold. Has been. A resin flow path 4 is formed at the peripheral edge portion of the thin metal plate 1 via the cross-sectional portion 3 of the thin metal plate 1, and a liquid silicone resin is injected from the gate 5 of the fixed-side mold plate 2 a. This liquid silicone resin is molded by filling the mold cavity from the silicone resin layer 6a on the front surface to the silicone resin layer 6b on the back surface through the resin flow path 4 in the cross section 3 of the metal thin plate 1. .

JP 11-309746 A

  By the way, in the metal separator, in order to reduce the size and weight, the thickness of the metal plate is reduced to reduce the thickness. For this reason, for example, when a fuel cell is stacked, a load generated in the power generation unit in the central region of the metal separator and the seal unit provided around the power generation unit due to a manufacturing error of the seal member, the metal plate, or the MEA The difference may be large. As a result, there is a problem that a crack or a short circuit due to plastic deformation of the metal plate or a gas leak due to a seal failure is caused.

  The present invention solves this type of problem, can reduce the load difference between the power generation part and the seal part of the metal separator, prevents cracks and the like of the metal plate as much as possible, and provides a good seal. An object of the present invention is to provide a fuel cell capable of maintaining the properties.

  The present invention relates to a fuel cell in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte and a metal separator provided integrally with a seal member are laminated.

  The metal separator is composed of a power generation portion facing the electrode and a seal member, and is provided between the power generation portion and the seal portion, and when an external load is applied. And a deformable portion that can be deformed more easily than other portions.

  The power generation unit preferably has a concavo-convex shape portion that forms a reaction gas flow path for flowing the reaction gas along the electrode, and the deformation portion has a bead shape portion that protrudes toward the reaction gas flow channel side. .

  Furthermore, it is preferable that a deformation | transformation part has a thin wall shape compared with another site | part.

  According to the present invention, for example, even if a difference in load generated between the power generation unit in the central region of the metal separator and the seal unit around the power generation unit is increased due to a manufacturing error of the seal member, the metal plate, or the MEA. The difference in load can be absorbed (relieved) by the deformation of the deforming portion. Therefore, it is possible to prevent the metal plate from being cracked or short-circuited as much as possible and to maintain a good sealing property.

  FIG. 1 is an exploded schematic perspective view of a main part of a fuel cell 10 according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a fuel cell stack 11 in which the fuel cells 10 are stacked. FIG.

  The fuel cell 10 includes an electrolyte membrane / electrode structure 12, and a first metal separator 14 and a second metal separator 16 that sandwich the electrolyte membrane / electrode structure 12. The first metal separator 14 and the second metal separator 16 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 has been subjected to anticorrosion treatment.

  As shown in FIG. 1, the first metal separator 14 and the second metal separator 16 have a vertically long shape, the long side faces in the direction of gravity (arrow C direction), and the short side in the horizontal direction (arrow B direction). Configured to head. In addition, you may comprise so that a long side may go to a horizontal direction and a short side may go to a gravitational direction.

  Near the upper corners of the long side direction of the fuel cell 10, they communicate with each other in the direction of arrow A, and an oxidant gas supply communication hole 18a for supplying an oxidant gas, for example, an oxygen-containing gas, a fuel gas, For example, a fuel gas supply communication hole 20a for supplying a hydrogen-containing gas is provided.

  In the vicinity of the lower corners of the long side direction of the fuel cell 10, the fuel gas discharge communication hole 20 b for discharging the fuel gas and the oxidant gas for discharging the oxidant gas are communicated with each other in the direction of arrow A. A discharge communication hole 18b is provided.

  Two upper and lower (or one or more) coolings for supplying a cooling medium communicate with each other in the arrow A direction at one end edge of the fuel cell 10 in the short side direction (arrow B direction). A medium supply communication hole 22a is provided, and two upper and lower (or one or three or more) cooling media for discharging the cooling medium are provided at the other end edge in the short side direction of the fuel cell 10. A discharge communication hole 22b is provided.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 24 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode side electrode 26 and an anode side electrode 28 that sandwich the solid polymer electrolyte membrane 24. With.

  The cathode side electrode 26 and the anode side electrode 28 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like, and porous carbon particles carrying a platinum alloy on the surface. An electrode catalyst layer (not shown). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 24.

  As shown in FIGS. 1 and 3, the surface 14a of the first metal separator 14 facing the electrolyte membrane / electrode structure 12 is oxidized through an oxidant gas supply communication hole 18a and an oxidant gas discharge communication hole 18b. An agent gas flow path (reaction gas flow path) 30 is formed. The oxidant gas flow channel 30 has a plurality of wavy flow channel grooves (uneven portions) 30 a extending in the direction of arrow C, and the wavy flow channel groove 30 a is a metal plate that forms the first metal separator 14. It is provided by forming the in a concavo-convex shape.

  As shown in FIG. 4, a fuel gas flow path (reaction) that connects the fuel gas supply communication hole 20 a and the fuel gas discharge communication hole 20 b to the surface 16 a of the second metal separator 16 facing the electrolyte membrane / electrode structure 12. Gas channel) 32 is formed. The fuel gas flow channel 32 has a plurality of wavy flow channel grooves (uneven portions) 32 a extending in the direction of arrow C, and the wavy flow channel groove 32 a is a metal plate that constitutes the second metal separator 16. It is provided by forming in an uneven shape.

  Between the surface 16b of the second metal separator 16 and the surface 14b of the first metal separator 14, a cooling medium flow path 34 communicating with the cooling medium supply communication holes 22a and 22a and the cooling medium discharge communication holes 22b and 22b. Is formed (see FIG. 1). The cooling medium flow path 34 is formed to extend in the direction of arrow B by overlapping the wavy flow path groove 30 a of the oxidant gas flow path 30 and the wavy flow path groove 32 a of the fuel gas flow path 32. .

  A first seal member 36 is integrally formed on the surfaces 14 a and 14 b of the first metal separator 14 around the outer peripheral edge of the first metal separator 14. A second seal member 38 is integrally formed on the surfaces 16 a and 16 b of the second metal separator 16 around the outer peripheral edge of the second metal separator 16. As the first and second sealing members 36 and 38, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber or the like, cushion material, Alternatively, a packing material is used.

  As shown in FIG. 3, the first seal member 36 communicates the oxidant gas flow path 30 with the oxidant gas supply communication hole 18 a and the oxidant gas discharge communication hole 18 b on the surface 14 a side, and is a power generation unit. Circulating the flow path seal 36a provided surrounding the oxidant gas flow path 30, the fuel gas supply communication hole 20a, the fuel gas discharge communication hole 20b, the cooling medium supply communication hole 22a, and the cooling medium discharge communication hole 22b. And a circumferential seal portion 36b.

  The first metal separator 14 is provided with a deformable portion 40 that can be more easily deformed than other portions when an external load is applied between the oxidant gas flow channel 30 and the flow path seal portion 36a. As shown in FIG. 2, the deformable portion 40 has a bead-shaped portion 42 that protrudes toward the oxidant gas flow path 30, and the bead-shaped portion 42 is formed by performing bead processing on a metal plate. The bead shape portion 42 extends substantially along the longitudinal direction of the flow path seal portion 36 a, and the oxidant gas supply communication hole 18 a, the oxidant gas discharge communication hole 18 b, and the oxidant gas flow path 30. It is preferable to configure intermittently in each communication part. The bead shape portion 42 may be covered with the first seal member 36.

  As shown in FIG. 4, the second seal member 38 has a flow path seal portion 38a provided on the surface 16a side so as to surround the fuel gas flow path 32, the fuel gas supply communication hole 20a, and the fuel gas discharge communication hole 20b. And an oxidant gas supply communication hole 18a, an oxidant gas discharge communication hole 18b, a cooling medium supply communication hole 22a, and a circulating seal portion 38b that circulates the cooling medium discharge communication hole 22b.

  As shown in FIG. 1, the second seal member 38 includes a flow path seal portion 38c provided on the surface 16b side so as to surround the cooling medium flow path 34, the cooling medium supply communication hole 22a, and the cooling medium discharge communication hole 22b. And an oxidant gas supply communication hole 18a, an oxidant gas discharge communication hole 18b, a fuel gas supply communication hole 20a, and a circumferential seal portion 38d that circulates the fuel gas discharge communication hole 20b.

  As shown in FIG. 4, the second metal separator 16 is a deformable portion that can be more easily deformed than other portions when an external load is applied between the fuel gas flow channel 32 and the flow channel seal portion 38a. 44 is provided. As shown in FIG. 2, the deformable portion 44 has a bead-shaped portion 46 that protrudes toward the fuel gas flow path 32. The bead-shaped portion 46 extends substantially along the longitudinal direction of the flow path seal portion 38 a, and each communication portion of the fuel gas supply communication hole 20 a, the fuel gas discharge communication hole 20 b, and the fuel gas flow path 32. However, it is preferable to constitute intermittently.

  In a state where the electrolyte membrane / electrode structure 12 is sandwiched between the first metal separator 14 and the second metal separator 16, the bead shape portion 42 of the first metal separator 14 and the bead shape portion 46 of the second metal separator 16. And sandwich the solid polymer electrolyte membrane 24 constituting the electrolyte membrane / electrode structure 12 (see FIG. 2).

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

  First, in the fuel cell stack 11, an oxidant gas such as an oxygen-containing gas is supplied and a fuel gas such as a hydrogen-containing gas is supplied. Further, a cooling medium such as pure water or ethylene glycol is supplied.

  As shown in FIG. 1, the oxidant gas is introduced into the oxidant gas flow path 30 of the first metal separator 14 from the oxidant gas supply communication hole 18 a constituting each fuel cell 10. The oxidant gas moves vertically downward along the cathode side electrode 26 of the electrolyte membrane / electrode structure 12 (see FIG. 3).

  On the other hand, as shown in FIG. 4, the fuel gas is introduced into the fuel gas flow path 32 of the second metal separator 16 from the fuel gas supply communication hole 20 a constituting each fuel cell 10. The fuel gas moves vertically downward along the anode side electrode 28 of the electrolyte membrane / electrode structure 12.

  As described above, in each electrolyte membrane / electrode structure 12, the oxidizing gas supplied to the cathode side electrode 26 and the fuel gas supplied to the anode side electrode 28 are electrochemically reacted in the electrode catalyst layer. It is consumed and power is generated.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 26 is discharged from the oxidant gas discharge communication hole 18b (see FIGS. 1 and 3). Similarly, the fuel gas consumed by being supplied to the anode electrode 28 is discharged to the fuel gas discharge communication hole 20b (see FIG. 4).

  Further, as shown in FIG. 2, the cooling medium is introduced into the cooling medium flow path 34 between the first and second metal separators 14 and 16. The cooling medium flows along the arrow B direction (horizontal direction), cools the electrolyte membrane / electrode structure 12, and then is discharged into the cooling medium discharge communication hole 22b (see FIG. 1).

  By the way, as shown in FIG. 2, the fuel cell stack 11 stacks a plurality of fuel cells 10 in the direction of arrow A and applies a predetermined tightening load. Here, a dimensional error (manufacturing error) of the first and second seal members 36 and 38, a manufacturing error of the first and second metal separators 14 and 16, a manufacturing error of the electrolyte membrane / electrode structure 12, etc. are caused. Easy to do.

  For this reason, in particular, the first and second seal members 36 and 38 vary in surface pressure due to a difference in compression rate. Thereby, for example, in the first metal separator 14, the difference in surface pressure between the oxidant gas flow path 30 that is the power generation section and the flow path seal section 36 a is applied to the metal plate of the first metal separator 14 that is a rigid body as a shearing force. Works.

  In this case, in the first embodiment, as shown in FIGS. 2 and 3, the first metal separator 14 has a bead-shaped portion 42 between the oxidant gas flow path 30 and the flow path seal portion 36 a. A deformation part 40 is provided. As a result, even if the difference in load generated between the oxidant gas flow path 30 (power generation part) in the central region of the first metal separator 14 and the flow path seal part 36a around the oxidant gas flow path 30 increases. The difference in load can be absorbed (relaxed) by easily deforming the bead shape portion 42 constituting the deformable portion 40.

  Therefore, the first metal separator 14 prevents a short circuit as much as possible as well as cracking due to plastic deformation of a rigid metal plate, and also prevents leakage of oxidant gas and maintains good sealing performance. Can be obtained.

  On the other hand, in the second metal separator 16 as well, as shown in FIG. Even if the load difference to be increased becomes large, the bead-shaped portion 46 constituting the deformable portion 44 can be easily deformed to absorb this load difference, and the same effect as the first metal separator 14 described above can be obtained. Is obtained.

  Furthermore, in the first embodiment, the bead-shaped portion 42 in which the deformable portions 40 and 44 extend along the longitudinal direction of the flow path seal portions 36a and 38a in the planes of the first and second metal separators 14 and 16, 46 is provided. For this reason, even if a change in the seal linear pressure due to a dimensional error occurs in the longitudinal direction of the flow path seal portions 36a and 38a, no undulation is caused on the surfaces of the first and second metal separators 14 and 16, and oxidation occurs. It becomes possible to prevent the leakage of the agent gas and the fuel gas as much as possible.

  Furthermore, as shown in FIG. 2, the bead-shaped portions 42 and 46 are in sliding contact with the solid polymer electrolyte membrane 24 constituting the electrolyte membrane / electrode structure 12 and sandwich the solid polymer electrolyte membrane 24 with each other. Yes. Therefore, the oxidant gas supplied to the oxidant gas flow channel 30 and the fuel gas supplied to the fuel gas flow channel 32 do not flow by bypassing the outer peripheral portion, and flow along the respective wavy flow channel grooves 30a and 32a. It will flow reliably and power generation efficiency will be improved.

  In the first embodiment, the deformable portions 40 and 44 are provided in the first and second metal separators 14 and 16 constituting each fuel cell 10. The deformable portions 40 and 44 may be provided only on the first and second metal separators 14 and 16 constituting the fuel cell 10 that is stacked every other place. The same applies to the second embodiment described below.

  FIG. 5 is a partial cross-sectional explanatory view of a fuel cell stack 62 in which fuel cells 60 according to the second embodiment of the present invention are stacked. The same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell 60 includes an electrolyte membrane / electrode structure 12, and a first metal separator 64 and a second metal separator 66 that sandwich the electrolyte membrane / electrode structure 12.

  The first metal separator 64 includes a deformable portion 68 that can be more easily deformed than other portions when an external load is applied between the oxidant gas flow path 30 and the flow path seal portion 36a, which are power generation portions. Provide. The deformation portion 68 has two thin portions 70 a and 70 b that substantially double around the outer periphery of the oxidizing gas channel 30.

  The second metal separator 66 is provided with a deformable portion 72 that can be more easily deformed than other portions when an external load is applied between the fuel gas flow channel 32 that is a power generation unit and the flow channel seal portion 38a. . The deformation portion 72 has thin portions 74 a and 74 b that substantially double around the outer periphery of the fuel gas channel 32.

  In the second embodiment configured as described above, when a tightening load is applied to the fuel cell stack 62 in the stacking direction, the oxidant gas flow path 30 is caused by manufacturing errors of the first and second seal members 36 and 38. And the flow path seal portion 36a and between the fuel gas flow channel 32 and the flow path seal portion 38a, the deformed portions 68 and 72 are converted into thin portions 70a and 70b and 74a and 74b, respectively. Therefore, the load difference can be reduced.

  Thereby, while preventing the plastic deformation of the metal plate which comprises the 1st and 2nd metal separators 64 and 66, it becomes possible to prevent the leakage of oxidant gas and fuel gas satisfactorily. The same effect as the form can be obtained.

  In the second embodiment, the deformable portions 68 and 72 have two thin portions 70a and 70b and 74a and 74b, respectively, but the present invention is not limited to this. For example, the entire portion between the thin portions 70a and 70b can be configured as a thin portion, or a rib shape can be adopted instead of the thin shape.

It is a principal part disassembled schematic perspective view of the fuel cell concerning the embodiment of the present invention. It is the II-II sectional view taken on the line of the fuel cell stack in which the said fuel cell was laminated | stacked in FIG. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is front explanatory drawing of the 2nd metal separator which comprises the said fuel cell. 1 is a partial cross-sectional explanatory view of a fuel cell stack in which fuel cells according to a first embodiment of the present invention are stacked. It is explanatory drawing of the manufacturing method of the silicone resin-metal composite body currently disclosed by patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 60 ... Fuel cell 11, 62 ... Fuel cell stack 12 ... Electrolyte membrane and electrode structure 14, 16, 64, 66 ... Metal separator 18a ... Oxidant gas supply communication hole 18b ... Oxidant gas discharge communication hole 20a ... Fuel Gas supply communication hole 20b ... Fuel gas discharge communication hole 22a ... Cooling medium supply communication hole 22b ... Cooling medium discharge communication hole 24 ... Solid polymer electrolyte membrane 26 ... Cathode side electrode 28 ... Anode side electrode 30 ... Oxidant gas flow path 30a 32a ... Wave-like channel groove 32 ... Fuel gas channel 34 ... Cooling medium channel 36, 38 ... Seal members 36a, 38a, 38c ... Channel seal part 36b, 38b, 38d ... Circumferential seal part 40, 44, 68, 72 ... Deformation part 42, 46 ... Bead-shaped part 70a, 70b, 74a, 74b ... Thin part

Claims (3)

A fuel cell in which an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte and a metal separator in which a seal member is provided integrally are laminated,
The metal separator includes a power generation unit facing the electrode;
A seal part configured by the seal member and surrounding the power generation part;
A deformable portion that is provided between the power generation portion and the seal portion and can be more easily deformed than other portions when an external load is applied;
A fuel cell comprising: 2. The fuel cell according to claim 1, wherein the power generation unit has a concavo-convex shape portion that forms a reaction gas flow path for flowing a reaction gas along the electrode, and
The fuel cell, wherein the deformable portion has a bead-shaped portion protruding toward the reaction gas flow path.   The fuel cell according to claim 1, wherein the deformable portion has a thinner shape than other portions.

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