JP5173641B2 - Fuel cell - Google Patents

Description

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, the electrolyte / electrode structure is sandwiched between a pair of metal separators, and at least either a fuel gas or an oxidant gas A reaction gas flow path for flowing a reaction gas in the surface direction of the electrolyte / electrode structure and a reaction gas communication hole for supplying the reaction gas in the stacking direction of the electrolyte / electrode structure and the metal separator are formed. The present invention relates to a fuel cell.

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

  In the fuel cell, a fuel gas channel (reactive gas channel) for flowing a fuel gas (reactive gas) along the anode side electrode and an oxidant gas along the cathode side electrode in the plane of the separator An oxidant gas flow path (reaction gas flow path) for flowing (reaction gas) is provided.

  Further, a fuel gas inlet communication hole and a fuel gas outlet communication hole that are fluid communication holes that penetrate the separator in the stacking direction and communicate with the fuel gas flow path, and an oxidant gas flow path An oxidant gas inlet communication hole and an oxidant gas outlet communication hole, which are fluid communication holes communicating with each other, are formed. In addition, a cooling medium flow path for cooling the electrolyte membrane / electrode structure is provided between the separators, and a cooling medium inlet communication hole and a cooling medium outlet that penetrate in the stacking direction and communicate with the cooling medium flow path are provided. A communication hole is formed.

  In this case, the reaction gas channel and the reaction gas communication hole communicate with each other via a connection channel having parallel grooves or the like in order to allow the reaction gas to flow smoothly and evenly. However, when the metal separator and the electrolyte membrane / electrode structure are tightened and fixed with a seal member interposed therebetween, the electrolyte membrane / electrode structure enters the connecting flow path, and a desired sealing property is obtained. There is a problem that it cannot be maintained and the reaction gas does not flow well.

  Therefore, in the gas manifold integrated separator disclosed in Patent Document 1, a fuel gas introduction port 3 is provided between the fuel gas introduction manifold hole 1 and the gas flow channel groove portion 2 as shown in FIG. Yes. The fuel gas inlet 3 is covered with a flat plate 4 and has a tunnel structure. This prevents the solid polymer electrolyte membrane from blocking the fuel gas inlet 3 and obstructing gas flow when incorporated in a fuel cell.

  Here, the fuel gas inlet 3 is formed in the shape of several grooves, and a step portion 5 is provided to cover with the flat plate 4. A flat plate 4 is bonded to the stepped portion 5 by adhesion, and the surface of the flat plate 4 is designed to be flush with the surface of the gas manifold integrated separator.

  Further, the portion other than the gas flow channel groove 2 on the surface of the gas manifold integrated separator is covered with a coating film made of ethylene propylene rubber. Reinforcing ribs made of ethylene propylene rubber are provided on end portions of the flat plate 4 parallel to the direction in which the fuel gas flows.

JP 2000-133289 A

  In the above-mentioned Patent Document 1, the gas manifold integrated separator is provided with a step portion 5 at the fuel gas introduction port 3, and a flat plate 4 is joined to the step portion 5. For this reason, the gas manifold integrated separator has a problem that the configuration is complicated and the dimension in the thickness direction is particularly large.

  The present invention solves this type of problem, and aims to simplify and reduce the size of the structure, and to allow reliable and smooth communication between the reaction gas flow path and the reaction gas communication hole. The purpose is to provide.

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, the electrolyte / electrode structure is sandwiched between a pair of metal separators, and at least either a fuel gas or an oxidant gas A reaction gas flow path for flowing a reaction gas in the surface direction of the electrolyte / electrode structure and a reaction gas communication hole for supplying the reaction gas in the stacking direction of the electrolyte / electrode structure and the metal separator are formed. The present invention relates to a fuel cell.

  The electrolyte / electrode structure is provided with a flow path portion having a plurality of reaction gas communication paths communicating between the reaction gas flow path and the reaction gas communication holes.

  The flow path section includes a thick reaction gas diffusion layer in which a reaction gas diffusion layer constituting at least one electrode is formed thick, and the thick reaction gas diffusion layer includes a plurality of reaction gas communication channels. Is preferably formed.

  Furthermore, it is preferable that the flow path portion includes a resin flow path member in which a plurality of reaction gas communication flow paths are formed, and the resin flow path member is disposed in contact with at least one of the electrodes.

  According to the present invention, since the electrolyte / electrode structure is provided with the flow path portion having the reaction gas communication flow path, the rigidity of the electrolyte / electrode structure is substantially improved. Therefore, the electrolyte / electrode structure can satisfactorily suppress deformation between the reaction gas communication channels. This simplifies the configuration and reduces the size, eliminates the pressure drop in the seal portion, and enables reliable and smooth communication between the reaction gas flow path and the reaction gas communication hole.

  FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to the first embodiment of the present invention. FIG. 2 is a diagram of a fuel cell stack 12 in which a plurality of the fuel cells 10 are stacked in the direction of arrow A. In FIG. 1, it is II-II sectional view explanatory drawing.

  As shown in FIG. 1, in the fuel cell 10, an electrolyte membrane / electrode structure (electrolyte / electrode structure) 14 is sandwiched between first and second metal separators 16 and 18. The 1st and 2nd metal separators 16 and 18 are comprised by metal plates, such as a steel plate, a stainless steel plate, an aluminum plate, or a plated steel plate, for example.

  One end edge of the fuel cell 10 in the direction of arrow B (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, for example, an oxygen-containing gas An agent gas inlet communication hole 20a, a cooling medium outlet communication hole 22b for discharging a cooling medium, and a fuel gas outlet communication hole 24b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided in an arrow C direction (vertical direction). Are provided in an array.

  The other end edge in the direction of arrow B of the fuel cell 10 communicates with each other in the direction of arrow A, a fuel gas inlet communication hole 24a for supplying fuel gas, and a cooling medium inlet communication hole for supplying a cooling medium. 22a and an oxidizing gas outlet communication hole 20b for discharging the oxidizing gas are arranged in the direction of arrow C. The oxidant gas inlet communication hole 20a, the oxidant gas outlet communication hole 20b, the fuel gas inlet communication hole 24a, and the fuel gas outlet communication hole 24b constitute a reaction gas communication hole.

  As shown in FIGS. 1 and 3, on the surface 16a of the first metal separator 16 on the electrolyte membrane / electrode structure 14 side, for example, an oxidant gas channel (reactive gas channel) extending in the arrow B direction. 26 is provided. The oxidant gas flow path 26 includes a plurality of grooves provided by forming the first metal separator 16 into a wave shape.

  A first seal member (rubber seal member) 32 is integrated with the surfaces 16a and 16b of the first metal separator 16 by baking or injection molding around the outer peripheral end of the first metal separator 16. . The first seal member 32 uses, for example, a seal material such as EPDM, NBR, fluorine rubber, silicon rubber, fluorosilicon rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, a cushion material, or a packing material. To do.

  The first seal member 32 includes a first flat part 34 integrated with the surface 16 a of the first metal separator 16 and a second flat part 36 integrated with the surface 16 b of the first metal separator 16. As shown in FIG. 3, the first flat portion 34 is formed so as to surround the periphery of the oxidant gas inlet communication hole 20 a and the oxidant gas outlet communication hole 20 b so as to communicate with the oxidant gas flow path 26. On the other hand, the second flat portion 36 is formed by communicating the cooling medium inlet communication hole 22a and the cooling medium outlet communication hole 22b with a cooling medium flow path (described later).

  As shown in FIGS. 1 and 4, the surface 18a of the second metal separator 18 on the electrolyte membrane / electrode structure 14 side communicates with the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b, and the arrow B A fuel gas channel (reactive gas channel) 40 extending in the direction is formed. The fuel gas channel 40 includes a plurality of grooves, and the fuel gas channel 40 communicates with the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b as described later.

  As shown in FIG. 1, a cooling medium flow path 46 communicating with the cooling medium inlet communication hole 22a and the cooling medium outlet communication hole 22b is formed on the surface 18b opposite to the surface 18a of the second metal separator 18. .

  A second seal member (rubber seal member) 48 is integrated with the surfaces 18 a and 18 b of the second metal separator 18 around the outer peripheral end of the second metal separator 18. The second seal member 48 is made of the same material as the first seal member 32 described above.

  As shown in FIG. 4, the second seal member 48 includes an outer convex seal 50 a provided on the surface 18 a in the vicinity of the outer peripheral end of the second metal separator 18, and inward from the outer convex seal 50 a. An inner convex seal 50b is provided at a predetermined distance. The inner convex seal 50b closes the fuel gas flow path 40.

  As shown in FIG. 1, on the surface 18b of the second metal separator 18, an outer convex seal 56a that constitutes the second seal member 48, and a cooling medium flow path 46 that is spaced inward of the outer convex seal 56a. And an inner convex seal 56b provided so as to surround. A plurality of passages 62a and 62b communicating with the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b are formed on the surface 18b of the second metal separator 18, respectively. The passages 62a and 62b communicate with the plurality of holes 64a and 64b, and the holes 64a and 64b communicate with the fuel gas flow path 40 provided on the surface 18a (see FIG. 4).

  As shown in FIG. 1, the electrolyte membrane / electrode structure 14 includes, for example, a solid polymer electrolyte membrane 70 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side sandwiching the solid polymer electrolyte membrane 70. The electrode 72 and the cathode side electrode 74 are provided. The surface area of the anode side electrode 72 is set to be smaller than the surface areas of the cathode side electrode 74 and the solid polymer electrolyte membrane 70 and constitutes a so-called step MEA.

  As shown in FIGS. 1 and 5, at the diagonal position of the electrolyte membrane / electrode structure 14, an inlet projecting in the direction of arrow B corresponding to the oxidant gas inlet communication hole 20a and the oxidant gas outlet communication hole 20b. A channel portion 76a and an outlet channel portion 76b are provided. The inlet channel portion 76 a and the outlet channel portion 76 b have a solid polymer electrolyte membrane 70 and a cathode side electrode 74.

  As shown in FIGS. 2 and 6, the anode side electrode 72 and the cathode side electrode 74 are composed of gas diffusion layers 72a and 74a made of carbon paper or the like, and porous carbon particles having a platinum alloy supported on the surface. And electrode catalyst layers 72b and 74b formed uniformly on the surfaces of the layers 72a and 74a. The electrode catalyst layers 72 b and 74 b are formed on both surfaces of the solid polymer electrolyte membrane 70.

  As shown in FIGS. 5 and 6, the inlet channel portion 76a and the outlet channel portion 76b have thick gas diffusion layers 74aa and 74ab in which the gas diffusion layer 74a constituting the cathode side electrode 74 is formed thick. . The thick gas diffusion layers 74aa and 74ab are notched at predetermined intervals (or between the plurality of thick gas diffusion layers 74aa and between the thick gas diffusion layers 74ab), and a plurality of oxidant gas communication channels (reactive gases) Communication channels 78a, 78b are formed.

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

  First, as shown in FIG. 1, a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 24a, and an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 20a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 22a.

  For this reason, as shown in FIG. 4, the fuel gas passes through the passage 62a from the fuel gas inlet communication hole 24a of the second metal separator 18, and then moves from the plurality of holes 64a to the surface 18a side to flow the fuel gas. It is introduced into the road 40. In the fuel gas channel 40, the fuel gas is supplied to the anode side electrode 72 constituting the electrolyte membrane / electrode structure 14 while moving in the arrow B direction.

  On the other hand, as shown in FIGS. 2 and 6, the oxidant gas is supplied to each of the thick gas diffusion layers 74aa provided in the inlet channel portion 76a of the electrolyte membrane / electrode structure 14 from the oxidant gas inlet communication hole 20a. The gas is introduced into the oxidant gas flow path 26 of the first metal separator 16 through the oxidant gas communication flow path 78a. As a result, the oxidant gas is supplied to the cathode-side electrode 74 constituting the electrolyte membrane / electrode structure 14 while moving the oxidant gas flow path 26 in the direction of arrow B as shown in FIGS. The

  Therefore, in the electrolyte membrane / electrode structure 14, the oxidant gas supplied to the cathode side electrode 74 and the fuel gas supplied to the anode side electrode 72 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is done.

  Next, the fuel gas consumed by being supplied to the anode electrode 72 moves from the plurality of holes 64b to the passage 62b, and is then discharged in the direction of arrow A along the fuel gas outlet communication hole 24b. Similarly, the oxidant gas consumed by being supplied to the cathode electrode 74 is communicated with the oxidant gas outlet from each oxidant gas communication channel 78 b provided in the outlet channel part 76 b of the electrolyte membrane / electrode structure 14. The ink is discharged in the direction of arrow A along the hole 20b.

  The cooling medium supplied to the cooling medium inlet communication hole 22a is introduced into the cooling medium flow path 46 between the first and second metal separators 16 and 18, and then flows in the direction of arrow B. The cooling medium cools the electrolyte membrane / electrode structure 14 and then is discharged to the cooling medium outlet communication hole 22b.

  In this case, in the first embodiment, as shown in FIGS. 5 and 6, the electrolyte membrane / electrode structure 14 has an inlet channel protruding in the direction of arrow B corresponding to the oxidant gas inlet communication hole 20 a. A portion 76a is provided. The inlet channel portion 76a has a thick gas diffusion layer 74aa, and a plurality of oxidant gas communication channels 78a are formed in the thick gas diffusion layer 74aa.

  Therefore, the rigidity of the electrolyte membrane / electrode structure 14 is substantially improved at the connecting portion (so-called bridge portion) between the oxidizing gas inlet communication hole 20a and the oxidizing gas channel 26. For this reason, for example, compared with the structure in which the bridge portion is formed on the second metal separator 18 side, the electrolyte membrane / electrode structure 14 can be favorably suppressed from being deformed at the bridge portion.

  As a result, the fuel cell 10 simplifies the configuration and reduces the size of the fuel cell 10, eliminates the pressure drop in the seal portion, and reliably and smoothly between the oxidant gas flow path 26 and the oxidant gas inlet communication hole 20 a. The effect that it becomes possible to communicate with is obtained.

  On the other hand, the electrolyte membrane / electrode structure 14 is provided with an outlet channel portion 76b protruding in the direction of arrow B corresponding to the oxidizing gas outlet communication hole 20b. The outlet channel portion 76b is configured in the same manner as the inlet channel portion 76a described above, and has similar effects such as eliminating the linear pressure loss of the seal portion and enabling a smooth flow of the oxidant gas. can get.

  In the first embodiment, the electrolyte membrane / electrode structure 14 forms the step MEA. However, the present invention is not limited to this, and the solid polymer electrolyte membrane 70, the anode side electrode 72, and the cathode side electrode are not limited thereto. 74 may be set to the same surface area.

  FIG. 7 is an exploded perspective view of a main part of a fuel cell 80 according to the second embodiment of the present invention. 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. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  In the fuel cell 80, an inlet channel portion 76a and an outlet channel portion 76b are provided at diagonal positions of the electrolyte membrane / electrode structure 14 corresponding to the oxidant gas inlet communication hole 20a and the oxidant gas outlet communication hole 20b. It is done. The inlet channel portion 76 a and the outlet channel portion 76 b are constituted by the solid polymer electrolyte membrane 70 and a gas diffusion layer 74 a that constitutes the cathode side electrode 74. A resin inlet flow channel member 82a and a resin outlet flow channel member 82b are disposed in contact with the inlet flow channel portion 76a and the outlet flow channel portion 76b as flow channel portions.

  The resin inlet channel member 82a and the resin outlet channel member 82b are, for example, PTFE (polytetrafluoroethylene), PC (polycarbonate), PPS (polyphenylene sulfide), PEEK (polyetheretherketone), PA (polyamide). 6. It is configured in a block shape by a resin material such as PA66 or polyamide resin, and a plurality of oxidizing gas communication channels 78a and 78b are provided (see FIGS. 7 and 8).

  In the second embodiment configured as described above, the inlet channel portion 76a of the electrolyte membrane / electrode structure 14 is held by the resin inlet channel member 82a, and the outlet channel portion 76b is made of the resin outlet channel. It is held by the road member 82b. For this reason, the rigidity of the electrolyte membrane / electrode structure 14 is substantially improved, and the same effect as in the first embodiment can be obtained.

  FIG. 9 is an exploded perspective view of a main part of a fuel cell 90 according to the third embodiment of the present invention.

  In the fuel cell 90, an electrolyte membrane / electrode structure (electrolyte / electrode structure) 92 is sandwiched between first and second metal separators 94 and 96.

  The electrolyte membrane / electrode structure 92 includes a solid polymer electrolyte membrane 98, and an anode side electrode 72 and a cathode side electrode 74 that sandwich the solid polymer electrolyte membrane 98. The anode side electrode 72 and the cathode side electrode 74 are set to have the same surface area and are set to have a smaller surface area than the solid polymer electrolyte membrane 98.

  As shown in FIG. 10, the surface of the electrolyte membrane / electrode structure 92 facing the first metal separator 94 protrudes in the direction of arrow B corresponding to the oxidant gas inlet communication hole 20a and the oxidant gas outlet communication hole 20b. An inlet channel portion 76a and an outlet channel portion 76b are provided.

  As shown in FIG. 9, the surface of the electrolyte membrane / electrode structure 92 facing the second metal separator 96 has an inlet projecting in the direction of arrow B corresponding to the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b. A channel portion 100a and an outlet channel portion 100b are provided. The inlet channel portion 100 a and the outlet channel portion 100 b include a solid polymer electrolyte membrane 70 and an anode side electrode 72.

  The inlet channel portion 100a and the outlet channel portion 100b include thick gas diffusion layers 72aa and 72ab in which the gas diffusion layer 72a constituting the anode side electrode 72 is formed thick. The thick gas diffusion layers 72aa and 72ab are cut out at predetermined intervals (or between the thick gas diffusion layers 72aa and between the thick gas diffusion layers 72ab), and a plurality of fuel gas communication channels (reactive gas communication) Channels) 102a and 102b are formed.

  In the third embodiment configured as described above, the electrolyte membrane / electrode structure 92 is formed at the bridge portion between the oxidant gas inlet communication hole 20a, the oxidant gas outlet communication hole 20b, and the oxidant gas flow path 26. While having an inlet channel portion 76a and an outlet channel portion 76b, an inlet channel portion 100a and an outlet channel portion are provided at a bridge portion between the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b and the fuel gas channel 40. 100b.

  Therefore, since the electrolyte membrane / electrode structure 92 is substantially improved in rigidity corresponding to each bridge portion, deformation of the electrolyte membrane / electrode structure 92 can be reliably prevented, The same effect as in the first embodiment can be obtained. As in the second embodiment, the electrolyte membrane / electrode structure 92 can use a resin inlet channel member 82a and a resin outlet channel member 82b as the channel portion.

It is a principal part disassembled perspective explanatory drawing of the fuel cell which concerns on the 1st Embodiment of this invention. FIG. 2 is a cross-sectional explanatory view taken along the line II-II in FIG. 1 of the fuel cell stack in which the fuel cells are stacked. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is explanatory drawing of one surface of the 2nd metal separator which comprises the said fuel cell. It is front explanatory drawing of the electrolyte membrane and electrode structure which comprises the said fuel cell. FIG. 3 is a schematic perspective explanatory view of an inlet channel portion provided in the electrolyte membrane / electrode structure. It is a principal part disassembled perspective explanatory drawing of the fuel cell which concerns on the 2nd Embodiment of this invention. FIG. 2 is a schematic perspective explanatory view of an inlet channel portion provided in an electrolyte membrane / electrode structure constituting the fuel cell. It is a principal part disassembled perspective explanatory drawing of the fuel cell which concerns on the 3rd Embodiment of this invention. It is front explanatory drawing of the electrolyte membrane and electrode structure which comprises the said fuel cell. FIG. 6 is a perspective explanatory view of a gas manifold integrated separator disclosed in Patent Document 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 80, 90 ... Fuel cell 12 ... Fuel cell stack 14, 92 ... Electrolyte membrane and electrode structure 16, 18, 94, 96 ... Metal separator 20a ... Oxidant gas inlet communication hole 20b ... Oxidant gas outlet communication hole 22a ... Cooling medium inlet communication hole 22b ... Cooling medium outlet communication hole 24a ... Fuel gas inlet communication hole 24b ... Fuel gas outlet communication hole 26 ... Oxidant gas flow path 32, 48 ... Seal member 40 ... Fuel gas flow path 46 ... Cooling medium Flow path 70, 98 ... Solid polymer electrolyte membrane 72 ... Anode side electrode 72a, 74a ... Gas diffusion layer 72aa, 72ab, 74aa, 74ab ... Thick gas diffusion layer 72b, 74b ... Electrode catalyst layer 74 ... Cathode side electrode 76a, DESCRIPTION OF SYMBOLS 100a ... Inlet channel part 76b, 100b ... Outlet channel part 78a, 78b ... Oxidant gas communication channel 82a ... Resin inlet channel member 82b ... Tree Ltd. outlet channel member 102a, 102b ... fuel gas communication passage

Claims (3)

An electrolyte / electrode structure having a pair of electrodes disposed on both sides of the electrolyte, the electrolyte / electrode structure being sandwiched between a pair of metal separators, and at least a reaction gas that is either a fuel gas or an oxidant gas A fuel cell in which a reaction gas flow channel that flows in the surface direction of the electrolyte / electrode structure and a reaction gas communication hole that supplies the reaction gas in the stacking direction of the electrolyte / electrode structure and the metal separator are formed. There,
The fuel cell according to claim 1, wherein the electrolyte / electrode structure is provided with a flow path portion having a plurality of reaction gas communication channels communicating between the reaction gas flow channel and the reaction gas communication hole. 2. The fuel cell according to claim 1, wherein the flow path portion includes a thick reactive gas diffusion layer in which a reactive gas diffusion layer constituting at least one of the electrodes is formed thick,
The fuel cell, wherein the thick reactive gas diffusion layer is formed with a plurality of reactive gas communication channels. 2. The fuel cell according to claim 1, wherein the flow path portion includes a resin flow path member in which a plurality of the reaction gas communication flow paths are formed,
The fuel cell, wherein the resin channel member is disposed in contact with at least one of the electrodes.

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