JP2017050206A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell that, in particular, can further simplify the constitution thereof and also can be manufactured economically.SOLUTION: A power generation cell 10 sandwiches an MEA 12 having a resin frame by a first metal separator 14 and a second metal separator 16. The MEA 12 having a resin frame fixes an electrolyte membrane-electrode structure 12a and a resin frame member 54 by adhesion. The first metal separator 14 is provided with an inlet buffer section 26a contiguous to an inlet side end of an oxidant gas passage 24. In a bridge section 56a of the resin frame member 54, an oxidant gas inlet coupling passage 58a coupling an oxidant gas inlet communication hole 18a and the inlet buffer section 26a is formed.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fuel cell in which separators are stacked on both sides of an MEA with a resin frame.

  In general, a polymer electrolyte fuel cell employs a polymer electrolyte membrane made of a polymer ion exchange membrane. The fuel cell includes an electrolyte membrane / electrode structure (MEA) in which an anode electrode is disposed on one surface of a solid polymer electrolyte membrane and a cathode electrode is disposed on the other surface of the solid polymer electrolyte membrane. Yes. The anode electrode and the cathode electrode each have a catalyst layer (electrode catalyst layer) and a gas diffusion layer (porous carbon).

  The electrolyte membrane / electrode structure constitutes a power generation cell (unit fuel cell) by being sandwiched between separators (bipolar plates). The power generation cells are used as, for example, an in-vehicle fuel cell stack by being stacked in a predetermined number.

  In the electrolyte membrane / electrode structure, one gas diffusion layer is set to a plane size smaller than that of the solid polymer electrolyte membrane, and the other gas diffusion layer is set to the same plane size as the solid polymer electrolyte membrane. In other words, a so-called step MEA may be formed. At that time, various proposals have been made to reduce the amount of the relatively expensive solid polymer electrolyte membrane used and to protect the solid polymer electrolyte membrane having a thin film shape and low strength.

  For example, in the fuel cell disclosed in Patent Document 1, an MEA with a resin frame in which a resin frame member is provided around the outer periphery of the solid polymer electrolyte membrane is employed. In this fuel cell, a first buffer portion that is located outside the power generation region and is connected to one reaction gas flow path is formed on one surface of the resin frame member. On the other surface of the resin frame member, there is formed a second buffer portion that is located outside the power generation region and connected to the other reaction gas flow path, and is configured separately from the first buffer portion. Yes.

  For this reason, the 1st buffer part and 2nd buffer part which each have a desired shape can be formed in the both surfaces of a resin frame member separately. Therefore, the reaction gas can be smoothly circulated through the first reaction gas channel and the second reaction gas channel, respectively.

JP 2013-201085 A

  The present invention has been made in connection with a fuel cell provided with this type of MEA with a resin frame, and particularly provides a fuel cell that can be further simplified in construction and can be manufactured economically. For the purpose.

  The fuel cell according to the present invention includes an MEA with a resin frame, and separators that have an outer dimension larger than the outer dimension of the MEA with a resin frame and are stacked on both sides of the MEA with a resin frame. In the MEA with a resin frame, the first electrode is provided on one surface of the solid polymer electrolyte membrane, the second electrode is provided on the other surface of the solid polymer electrolyte membrane, and the planar dimension of the first electrode is And a step MEA set to a size larger than the planar size of the second electrode. The step MEA is provided with a resin frame member around the outer periphery of the solid polymer electrolyte membrane.

  The separator is formed with a reaction gas flow path for allowing a reaction gas to flow along the electrode surface, and a buffer portion connected to the reaction gas flow path. The separator is further formed with a reaction gas communication hole for allowing the reaction gas to flow in the stacking direction of the MEA with a resin frame and the separator, and a flat connection part provided between the buffer part and the reaction gas communication hole. Has been.

  On the other hand, the resin frame member is formed with a connection flow path for connecting the reaction gas communication hole and the buffer portion at the bridge portion that contacts the connection portion, and the resin frame member is bonded to the separator that contacts both surfaces. It is joined by an agent.

  Moreover, in this fuel cell, it is preferable that the resin frame member has a U-shaped cross section that covers the outer peripheral end of the step MEA. At that time, a fuel gas connection flow path through which fuel gas, which is one of the reaction gases, flows is formed as a connection flow path on one surface of the resin frame member. On the other surface of the resin frame member, an oxidant gas connection channel for allowing an oxidant gas as the other reaction gas to flow is formed as a connection channel.

  According to the present invention, the separator is provided with the buffer portion, and the connecting channel for connecting the reaction gas communication hole and the buffer portion is formed in the bridge portion of the resin frame member. Therefore, since the buffer portion is not provided on the resin frame member, a phenomenon that bias force acts on the buffer portion due to an increase in load or the like does not occur in the resin frame member.

  As a result, it is possible to reliably suppress the occurrence of cracks in the resin frame member and the occurrence of performance degradation such as cross leak. For this reason, especially the structure of the whole fuel cell can be further simplified, and it becomes possible to manufacture the said fuel cell economically.

It is a principal part disassembled perspective explanatory drawing of the power generation cell which concerns on embodiment of this invention. It is the II-II sectional view taken on the line of the said electric power generation cell in FIG. It is front explanatory drawing of the 1st metal separator which comprises the said electric power generation cell. It is front explanatory drawing of MEA with a resin frame which comprises the said electric power generation cell. It is the VV sectional view taken on the line of the said electric power generation cell in FIG. It is the VI-VI sectional view taken on the line of the said electric power generation cell in FIG.

  As shown in FIGS. 1 and 2, a plurality of power generation cells (fuel cells) 10 according to an embodiment of the present invention are stacked in, for example, an arrow A direction (horizontal direction) or an arrow C direction (gravity direction). Configure the stack. The fuel cell stack is mounted on, for example, a fuel cell electric vehicle (not shown) as an in-vehicle fuel cell stack.

  In the power generation cell 10, a MEA with resin frame (electrolyte membrane / electrode structure with resin frame) 12 is sandwiched between a first metal separator 14 and a second metal separator 16. The first metal separator 14 and the second metal separator 16 have a horizontally long (or vertically long) rectangular shape and an outer dimension larger than the outer dimension of the MEA 12 with a resin frame (see FIG. 1).

  For example, the first metal separator 14 and the second metal separator 16 are formed by pressing a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal thin plate having a surface treatment for anticorrosion applied to the metal surface. Configured. For example, a carbon separator may be used instead of the first metal separator 14 and the second metal separator 16.

  One end edge of the first metal separator 14 and the second metal separator 16 in the direction of arrow B, which is the long side direction, communicates with each other in the direction of arrow A (stacking direction), and the oxidant gas inlet communication hole 18a and the fuel gas. An outlet communication hole 20b is provided. The oxidant gas inlet communication hole 18a supplies an oxidant gas (the other reaction gas), for example, an oxygen-containing gas. The fuel gas outlet communication hole 20b discharges fuel gas (one reaction gas), for example, a hydrogen-containing gas.

  The other end edge of the first metal separator 14 and the second metal separator 16 in the direction of arrow B communicates with each other in the direction of arrow A, and a fuel gas inlet communication hole 20a and an oxidant gas outlet communication hole 18b are provided in the arrow C direction. Arranged in the direction. The fuel gas inlet communication hole 20a supplies fuel gas, and the oxidant gas outlet communication hole 18b discharges oxidant gas.

  The cooling medium is supplied to both edge portions in the short side direction (arrow C direction) of the first metal separator 14 and the second metal separator 16 in the direction of arrow A toward the oxidant gas inlet communication hole 18a. Cooling medium inlet communication holes 22a are provided vertically. At both ends of the first metal separator 14 and the second metal separator 16 in the short side direction, cooling medium outlet communication holes 22b for discharging the cooling medium are provided vertically on the fuel gas inlet communication hole 20a side.

  As shown in FIG. 3, for example, an oxidant gas flow path 24 extending in the direction of arrow B is formed on the surface 14 a of the first metal separator 14 facing the MEA 12 with a resin frame. The oxidant gas flow path 24 has a plurality of wave-shaped flow path grooves (or linear flow path grooves) 24a arranged in parallel with each other.

  The inlet side buffer 26a is located outside the power generation region at the inlet side end of the oxidant gas flow channel 24, while the outlet side end of the oxidant gas flow channel 24 is located outside the power generation region. The outlet buffer unit 26b is continuous. Each of the inlet buffer portion 26a and the outlet buffer portion 26b has a plurality of embosses, but may have a plurality of line-shaped convex portions together with or instead of the embosses.

  The surface 14a is provided with a flat inlet coupling portion 28a located between the inlet buffer portion 26a and the oxidant gas inlet communication hole 18a. The surface 14a is provided with a flat outlet connecting portion 28b located between the outlet buffer portion 26b and the oxidizing gas outlet communication hole 18b.

  As shown in FIG. 1, for example, a fuel gas passage 32 extending in the direction of arrow B is provided on the surface 16 a of the second metal separator 16 facing the MEA 12 with a resin frame. The fuel gas flow path 32 has a plurality of wavy flow path grooves (or straight flow path grooves) 32a arranged in parallel with each other.

  An inlet buffer 34a is located outside the power generation region at the inlet side end of the fuel gas channel 32, while an outlet located outside the power generation region is located at the outlet side end of the fuel gas channel 32. The buffer unit 34b is connected. Each of the inlet buffer portion 34a and the outlet buffer portion 34b has a plurality of embosses, but may have a plurality of line-shaped convex portions together with or instead of the embosses.

  The surface 16a is provided with a flat inlet connection part 36a located between the inlet buffer part 34a and the fuel gas inlet communication hole 20a. The surface 16a is provided with a flat outlet connection part 36b located between the outlet buffer part 34b and the fuel gas outlet communication hole 20b. In addition, while providing the several hole part which penetrates the 2nd metal separator 16, you may provide a groove part in the surface 16a, 16b by the upstream and downstream of the said hole part.

  A cooling medium flow path 42 is formed between the surface 14 b of the first metal separator 14 and the surface 16 b of the second metal separator 16 that are adjacent to each other. The cooling medium flow path 42 communicates with the cooling medium inlet communication hole 22a and the cooling medium outlet communication hole 22b. The cooling medium channel 42 is formed by overlapping the back surface shape of the first metal separator 14 in which the oxidant gas channel 24 is formed and the back surface shape of the second metal separator 16 in which the fuel gas channel 32 is formed. The

  As shown in FIGS. 1 and 2, the first seal member 44 is integrated with the surfaces 14 a and 14 b of the first metal separator 14 around the outer peripheral end portion of the first metal separator 14. The second seal member 46 is integrated with the surfaces 16 a and 16 b of the second metal separator 16 around the outer peripheral end of the second metal separator 16.

  As shown in FIGS. 2 and 3, the first seal member 44 has a convex seal 44 a that is provided on the surface 14 a side and abuts against the flat surface of the second seal member 46 of the adjacent second metal separator 16. As shown in FIG. 3, the convex seal 44a surrounds the oxidant gas flow path 24, the oxidant gas inlet communication hole 18a, and the oxidant gas outlet communication hole 18b and communicates them.

  As shown in FIG. 2, the second seal member 46 has a convex seal 46 a that is provided on the surface 16 a side and abuts against the flat surface of the first seal member 44. As shown in FIG. 1, the convex seal 46a surrounds the fuel gas passage 32, the fuel gas inlet communication hole 20a, and the fuel gas outlet communication hole 20b.

  For the first seal member 44 and the second seal member 46, 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, an elastic seal member such as a packing material is used.

  As shown in FIG. 2, the MEA 12 with a resin frame includes an electrolyte membrane / electrode structure 12 a that is a step MEA. The step MEA is an MEA in which the planar dimension of one electrode is different from the planar dimension of the other electrode, that is, has a step. Details will be described later.

  The electrolyte membrane / electrode structure 12a includes, for example, a solid polymer electrolyte membrane (cation exchange membrane) 48 in which a perfluorosulfonic acid thin film is impregnated with water. A cathode electrode (first electrode) 50 is provided on one surface of the solid polymer electrolyte membrane 48, and an anode electrode (second electrode) 52 is provided on the other surface of the solid polymer electrolyte membrane 48. It is done. The solid polymer electrolyte membrane 48 may use an HC (hydrocarbon) electrolyte in addition to the fluorine electrolyte.

  The planar dimension (outer dimension) of the anode electrode 52 is smaller than the planar dimension (outer dimension) of the solid polymer electrolyte membrane 48 and the cathode electrode 50. The cathode electrode 50 is set to have the same planar dimensions as the solid polymer electrolyte membrane 48. Instead of the above configuration, the cathode electrode 50 may be configured to have a smaller planar dimension than the solid polymer electrolyte membrane 48 and the anode electrode 52. At that time, the anode electrode 52 becomes the first electrode, and the cathode electrode 50 becomes the second electrode.

  The cathode electrode 50 and the anode electrode 52 are formed by uniformly applying a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the gas diffusion layer. And an electrode catalyst layer (not shown) to be formed. The electrode catalyst layer is formed on both surfaces of the solid polymer electrolyte membrane 48, for example.

  The MEA 12 with a resin frame includes a resin frame member 54 that is joined around the outer periphery of the solid polymer electrolyte membrane 48. The resin frame member 54 includes, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), A silicone resin, a fluororesin, or m-PPE (modified polyphenylene ether resin) is used. The resin frame member 54 is further made of PET (polyethylene terephthalate), PBT (polybutylene terephthalate), modified polyolefin, or the like.

  As shown in FIGS. 1 and 4, the resin frame member 54 has a U-shaped cross section that covers the outer peripheral end of the electrolyte membrane / electrode structure 12 a. Since the electrolyte membrane / electrode structure 12a forms the step MEA, the electrolyte membrane / electrode structure 12a can be firmly joined to the resin frame member 54 having a U-shaped cross section. At one end in the arrow B direction of the resin frame member 54, bridge portions (projections) 56a and 56b protruding outward in the arrow B direction are formed vertically. At the other end in the arrow B direction of the resin frame member 54, bridge portions (projections) 56c and 56d protruding outward in the arrow B direction are formed vertically.

  As shown in FIGS. 1, 3, and 5, the bridge portion 56 a contacts the inlet connection portion 28 a of the first metal separator 14 on the one surface 54 a side of the resin frame member 54. An oxidant gas inlet connection flow path 58a that connects the oxidant gas inlet communication hole 18a and the inlet buffer part 26a is formed in the bridge part 56a that contacts the inlet connection part 28a. The oxidant gas inlet connection flow path 58a is composed of a plurality of groove portions whose surfaces of the bridge portion 56a are parallel to each other in the vertical direction and cut out in a slit shape toward the arrow B direction.

  As shown in FIGS. 1 and 3, the bridge portion 56 d abuts on the outlet connection portion 28 b of the first metal separator 14 on the one surface 54 a side of the resin frame member 54. An oxidant gas outlet connection flow path 58b that connects the oxidant gas outlet communication hole 18b and the outlet buffer part 26b is formed in the bridge part 56d that contacts the outlet connection part 28b. The oxidant gas outlet connection flow path 58b is configured by a plurality of groove portions in which the surface of the bridge portion 56d is parallel to each other in the vertical direction and cut out in a slit shape toward the arrow B direction.

  As shown in FIGS. 1, 4, and 6, the bridge portion 56 c comes into contact with the inlet connection portion 36 a of the second metal separator 16 on the other surface 54 b side of the resin frame member 54. A fuel gas inlet connection flow path 60a that connects the fuel gas inlet communication hole 20a and the inlet buffer portion 34a is formed in the bridge portion 56c that contacts the inlet connection portion 36a. The fuel gas inlet connection flow path 60a is composed of a plurality of groove portions whose surfaces of the bridge portion 56c are parallel to each other in the vertical direction and cut out in a slit shape toward the arrow B direction.

  As shown in FIGS. 1 and 4, the bridge portion 56 b contacts the outlet connection portion 36 b of the second metal separator 16 on the other surface 54 b side of the resin frame member 54. A fuel gas outlet connection channel 60b that connects the fuel gas outlet communication hole 20b and the outlet buffer part 34b is formed in the bridge portion 56b that abuts the outlet connection portion 36b. The fuel gas outlet connection flow path 60b is configured by a plurality of groove portions in which the surface of the bridge portion 56b is parallel to each other in the vertical direction and cut out in a slit shape toward the arrow B direction.

  As shown in FIG. 2, the resin frame member 54 is bonded to the first metal separator 14 that is in contact with one surface 54a by an adhesive 62a. The resin frame member 54 is bonded to the second metal separator 16 in contact with the other surface 54b by an adhesive 62b. For example, a liquid seal or a hot melt agent is used as the adhesives 62a and 62b.

  The operation of the power generation 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 18a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 20a. Supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 22a.

  Therefore, the oxidant gas is supplied from the oxidant gas inlet communication hole 18a to the inlet connection portion 28a of the first metal separator 14, as shown in FIGS. A bridge portion 56a of the resin frame member 54 abuts on the inlet connection portion 28a, and an oxidant gas inlet connection flow path 58a is formed in the bridge portion 56a. Therefore, as shown in FIG. 5, the oxidant gas flows through the oxidant gas inlet connection flow path 58a, is introduced from the inlet buffer portion 26a into the oxidant gas flow path 24, moves in the direction of arrow B, and moves to the electrolyte membrane. -It is supplied to the cathode electrode 50 of the electrode structure 12a.

  On the other hand, the fuel gas is supplied from the fuel gas inlet communication hole 20a to the inlet connecting portion 36a of the second metal separator 16, as shown in FIGS. A bridge portion 56c of the resin frame member 54 contacts the inlet connection portion 36a, and a fuel gas inlet connection flow path 60a is formed in the bridge portion 56c. Therefore, as shown in FIG. 6, the fuel gas flows through the fuel gas inlet connection channel 60a, is introduced from the inlet buffer 34a into the fuel gas channel 32, moves in the direction of arrow B, and the electrolyte membrane / electrode structure. It is supplied to the anode electrode 52 of the body 12a.

  As a result, in the electrolyte membrane / electrode structure 12a, the oxidant gas supplied to the cathode electrode 50 and the fuel gas supplied to the anode electrode 52 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode electrode 50 flows from the outlet buffer part 26b of the first metal separator 14 through the oxidant gas outlet connection channel 58b as shown in FIGS. Further, the oxidant gas is discharged to the oxidant gas outlet communication hole 18b and is circulated in the arrow A direction.

  Similarly, the fuel gas consumed by being supplied to the anode electrode 52 flows from the outlet buffer portion 34b of the second metal separator 16 through the fuel gas outlet connection channel 60b as shown in FIGS. And fuel gas is discharged | emitted by the fuel gas exit communication hole 20b, and is distribute | circulated in the arrow A direction.

  Further, as shown in FIG. 1, the cooling medium supplied to the pair of upper and lower cooling medium inlet communication holes 22 a is introduced into the cooling medium flow path 42 between the first metal separator 14 and the second metal separator 16. . The cooling medium is supplied from each cooling medium inlet communication hole 22a to the cooling medium flow path 42, once flows along the inner side in the direction of arrow C, and then moves in the direction of arrow B to cool the MEA 12 with the resin frame. This cooling medium moves outward in the direction of arrow C, and then is discharged into a pair of upper and lower cooling medium outlet communication holes 22b.

  In this case, in this embodiment, for example, as shown in FIGS. 1 and 3, the first metal separator 14 is provided with an inlet buffer portion 26 a continuous with the inlet side end portion of the oxidant gas flow path 24. . On the other hand, the bridge portion 56a of the resin frame member 54 is formed with an oxidant gas inlet connection channel 58a that connects the oxidant gas inlet communication hole 18a and the inlet buffer portion 26a.

  Further, the first metal separator 14 is provided with an outlet buffer portion 26 b that is connected to an outlet side end portion of the oxidant gas flow path 24. On the other hand, in the bridge portion 56d of the resin frame member 54, an oxidant gas outlet connection flow path 58b that connects the oxidant gas outlet communication hole 18b and the outlet buffer portion 26b is formed.

  For this reason, the resin frame member 54 is not provided with an inlet buffer portion and an outlet buffer portion. Therefore, in the resin frame member 54, a phenomenon that a biasing force acts on the inlet buffer portion and the outlet buffer portion due to an increase in load or the like does not occur.

  As a result, it is possible to reliably prevent the resin frame member 54 from being cracked or causing a performance degradation such as cross leak. For this reason, especially the structure of the electric power generation cell 10 whole can be simplified further, and the effect that it becomes possible to manufacture the said electric power generation cell 10 economically is acquired. Note that, on the fuel gas channel 32 side, the same effects as those on the oxidant gas channel 24 side can be obtained.

  The power generation cell 10 is configured by sandwiching one MEA with a pair of separators, but is not limited thereto. For example, the first metal separator, the MEA with the first resin frame, the second metal separator, the MEA with the second resin frame, and the third separator are stacked in this order, and the cooling medium flow path is between the power generation units. A so-called thin-out cooling structure fuel cell may be adopted.

10 ... Power generation cell 12 ... MEA with resin frame
12a ... Electrolyte membrane / electrode structure 14, 16 ... Separator 18a ... Oxidant gas inlet communication hole 18b ... Oxidant gas outlet communication hole 20a ... Fuel gas inlet communication hole 20b ... Fuel gas outlet communication hole 22a ... Cooling medium inlet communication hole 22b ... Cooling medium outlet communication hole 24 ... Oxidant gas flow path 26a, 34a ... Inlet buffer part 26b, 34b ... Outlet buffer part 28a, 36a ... Inlet connection part 28b, 36b ... Outlet connection part 32 ... Fuel gas flow path 42 ... Cooling medium flow path 44, 46 ... Seal member 48 ... Solid polymer electrolyte membrane 50 ... Cathode electrode 52 ... Anode electrode 54 ... Resin frame members 56a, 56b, 56c, 56d ... Bridge portion 58a ... Oxidant gas inlet connection flow path 58b ... Oxidant gas outlet connection channel 60a ... Fuel gas inlet connection channel 60b ... Fuel gas outlet connection channels 62a, 62b ... Adhesive

Claims (2)

The first electrode is provided on one surface of the solid polymer electrolyte membrane, the second electrode is provided on the other surface of the solid polymer electrolyte membrane, and the planar dimension of the first electrode is the same as that of the second electrode. A MEA with a resin frame having a step MEA set to a dimension larger than a planar dimension, and a resin frame member provided around the outer periphery of the solid polymer electrolyte membrane;
A separator having an outer dimension larger than an outer dimension of the MEA with the resin frame, and laminated on both sides of the MEA with the resin frame;
A fuel cell comprising:
In the separator, a reaction gas flow path for allowing a reaction gas to flow along the electrode surface;
A buffer portion connected to the reaction gas flow path;
A reaction gas communication hole for flowing the reaction gas in the stacking direction of the MEA with the resin frame and the separator;
A flat connecting portion provided between the buffer portion and the reaction gas communication hole;
While is formed
In the resin frame member, a connection channel that connects the reaction gas communication hole and the buffer unit is formed in a bridge unit that contacts the connection unit, and
The fuel cell according to claim 1, wherein the resin frame member is bonded to the separator in contact with both surfaces by an adhesive. 2. The fuel cell according to claim 1, wherein the resin frame member has a U-shaped cross section covering an outer peripheral end of the step MEA.
On one surface of the resin frame member, a fuel gas connection flow path for flowing fuel gas that is one reaction gas is formed as the connection flow path.
An oxidant gas connection flow path for allowing an oxidant gas as the other reaction gas to flow is formed on the other surface of the resin frame member as the connection flow path.

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