JP2019033000A - Fuel battery - Google Patents

Abstract

To suppress deterioration of power generation performance.SOLUTION: A fuel battery comprises: MEGA 20 containing a MEA 10, an anode gas diffusion layer 16a arranged while nipping the MEA 10, and a cathode gas diffusion layer 16c; a seal member 40 arranged in the circumference of the MEGA 20; and an anode side separator 18a and a cathode side separator 18c which nip the MEGA 20 and the seal member 40. The cathode side separator 18c includes a coolant passage 24 in which an air for cooling the MEA 10 is circulated in a surface opposite to the MEGA 20. In the seal member 40, a heat conductivity of a part contacted to the cathode side separator 18c on a downstream side of the coolant passage 24 is larger than that contacted to the cathode side separator 18c on an upstream side of the coolant passage 24, and/or a heat conductivity rate of the part contacted to the cathode gas diffusion layer 16c on the downstream side of the coolant passage 24 is larger than that of the part contacted to the cathode gas diffusion layer 16c on the upstream side of the coolant passage 24.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell.

  A fuel cell is known in which a frame is disposed around a membrane electrode gas diffusion layer assembly, and the membrane electrode gas diffusion layer assembly and the frame are sandwiched between an anode separator and a cathode separator (for example, Patent Document 1). .

JP-A-2015-195189

  The cathode side separator has a refrigerant flow path through which a refrigerant for cooling the membrane electrode assembly flows. Since the membrane / electrode assembly generates heat by an electrochemical reaction, the temperature of the refrigerant flowing through the refrigerant flow path rises due to this heat generation. For this reason, the temperature of the refrigerant | coolant in a downstream becomes high compared with the temperature of the refrigerant | coolant in the upstream of a refrigerant flow path.

  When the membrane / electrode assembly is within an appropriate temperature range, the power generation performance is good, and the power generation performance is degraded even if the temperature is lower or higher than the appropriate temperature range. Since the temperature of the refrigerant flowing through the refrigerant flow path is low on the upstream side and high on the downstream side, the portion of the membrane electrode assembly located on the upstream side of the refrigerant flow path is lower than the appropriate temperature range, and the downstream The part located on the side may be higher than the appropriate temperature range. In this case, the power generation performance is degraded.

  This invention is made | formed in view of the said subject, and aims at suppressing the fall of electric power generation performance.

  The present invention relates to a membrane electrode gas diffusion layer assembly including a membrane electrode assembly and an anode gas diffusion layer and a cathode gas diffusion layer arranged with the membrane electrode assembly interposed therebetween, and the membrane electrode gas diffusion layer assembly. A seal member disposed around, and an anode-side separator and a cathode-side separator sandwiching the membrane-electrode gas diffusion layer assembly and the seal member, wherein the cathode-side separator is the membrane-electrode gas diffusion layer assembly A coolant channel through which a coolant for cooling the membrane electrode assembly flows on a surface opposite to the surface, and the seal member has a thermal conductivity of a portion in contact with the cathode separator on the downstream side of the coolant channel Is larger than the thermal conductivity of the portion in contact with the cathode separator on the upstream side of the refrigerant flow path and / or the portion in contact with the cathode gas diffusion layer on the downstream side of the refrigerant flow path. Greater than the thermal conductivity of the portion conductivity in contact with the cathode gas diffusion layer upstream of the coolant channel is a fuel cell.

  According to the present invention, it is possible to suppress a decrease in power generation performance.

FIG. 1 is an exploded perspective view of a single cell constituting the fuel cell according to the first embodiment. 2 is a cross-sectional view taken along a line AA in FIG. FIG. 3 is a cross-sectional view of a single cell constituting the fuel cell according to the second embodiment. 4 is a perspective view of a cathode-side separator in Example 2. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  The fuel cell of Example 1 is a polymer electrolyte fuel cell that generates power by receiving supply of a fuel gas (for example, hydrogen) and an oxidant gas (for example, air) as a reaction gas, and has a stack structure in which a large number of single cells are stacked. Have FIG. 1 is an exploded perspective view of a single cell 100 constituting the fuel cell according to the first embodiment.

  As shown in FIG. 1, the single cell 100 of Example 1 includes an anode side separator 18a, a membrane electrode gas diffusion layer assembly (MEGA) 20, and a cathode side separator 18c. A seal member 40 is disposed around the MEGA 20. In other words, the MEGA 20 is disposed inside the seal member 40. The MEGA 20 and the seal member 40 are sandwiched between the anode side separator 18a and the cathode side separator 18c.

  The anode-side separator 18a is formed of a member having gas barrier properties and electronic conductivity. For example, the anode-side separator 18a is formed of a carbon member such as dense carbon made of compressed carbon and impermeable to gas, or a metal member such as stainless steel. . The anode side separator 18a is provided with holes a1 and a2, the seal member 40 is provided with holes s1 and s2, and the peripheral member 70 disposed on both sides of the cathode side separator 18c has holes c1 and c2. Is provided. The peripheral member 70 is an insulating member such as a thermoplastic resin or a thermosetting resin. Hole a1, hole s1, and hole c1 communicate and define a supply manifold for supplying hydrogen. The holes a2, s2, and c2 communicate with each other to define a discharge manifold that discharges hydrogen. A fuel gas flow path 26 that extends from the supply manifold toward the discharge manifold and through which hydrogen supplied to the MEGA 20 flows is provided on the surface of the anode separator 18a on the MEGA 20 side. The peripheral member 70 may be made of the same material as the cathode separator 18c. That is, the cathode side separator 18 c may include the peripheral member 70.

  At least a portion of the central portion of the cathode side separator 18c facing the MEGA 20 is formed of a member having gas barrier properties and electronic conductivity. The cathode-side separator 18c is made of a metal member such as stainless steel having a concavo-convex shape formed by, for example, bending by press molding. An oxidant gas flow path 22 and a refrigerant flow path 24 through which air flows are formed in the cathode-side separator 18c according to the uneven shape in the thickness direction. The oxidant gas flow path 22 and the refrigerant flow path 24 extend linearly from one end of the cathode-side separator 18c toward the other end, and are disposed adjacent to each other. The air flowing through the oxidant gas flow path 22 and the refrigerant flow path 24 flows from the air supply port on one end side of the cathode side separator 18c toward the air discharge port on the other end side.

  The oxidant gas flow path 22 is formed by a recess 30 provided on the surface of the cathode side separator 18c on the MEGA 20 side and opened on the MEGA 20 side. Therefore, the air flowing through the oxidant gas flow path 22 is supplied to the MEGA 20 and used mainly for power generation. The refrigerant flow path 24 is formed by a concave portion 32 provided on the surface of the cathode side separator 18c opposite to the MEGA 20 and opened to the opposite side of the MEGA 20. Therefore, the air flowing through the refrigerant flow path 24 is mainly used for cooling the MEGA 20. Thus, the fuel cell of Example 1 is an air-cooled fuel cell.

  2 is a cross-sectional view taken along a line AA in FIG. As shown in FIG. 2, the MEGA 20 includes an electrolyte membrane 12, an anode catalyst layer 14a, a cathode catalyst layer 14c, an anode gas diffusion layer 16a, and a cathode gas diffusion layer 16c. The anode catalyst layer 14 a is provided on one surface of the electrolyte membrane 12, and the cathode catalyst layer 14 c is provided on the other surface of the electrolyte membrane 12. Thereby, the membrane electrode assembly (MEA: Membrane Electrode Assembly) 10 is formed. The electrolyte membrane 12 is a solid polymer membrane formed of, for example, a fluorine-based resin material or a hydrocarbon-based resin material having a sulfonic acid group, and has good proton conductivity in a wet state. The anode catalyst layer 14a and the cathode catalyst layer 14c are, for example, carbon particles (such as carbon black) supporting a catalyst (such as platinum or a platinum-cobalt alloy) that progresses an electrochemical reaction, and a solid polymer having a sulfonic acid group. And an ionomer having good proton conductivity in a wet state.

  The anode gas diffusion layer 16a and the cathode gas diffusion layer 16c are provided on both sides of the MEA 10 with the MEA 10 interposed therebetween. The anode gas diffusion layer 16a and the cathode gas diffusion layer 16c are formed of members having gas permeability and electron conductivity, and are formed of a porous carbon member such as carbon cloth or carbon paper. A water repellent layer for the purpose of adjusting the amount of water contained in the MEA 10 may be provided between the MEA 10 and the anode gas diffusion layer 16a and the cathode gas diffusion layer 16c.

  The seal member 40 includes a frame member 42 and adhesives 44 to 48. The frame member 42 is provided so as to surround the MEGA 20. The adhesive 44 adheres to the frame member 42, the anode side separator 18a, and the MEA 10, and is provided so as to surround the periphery of the fuel gas flow path 26. Thereby, the hydrogen flowing through the fuel gas passage 26 is sealed so as not to leak to the outside. The adhesive 44 may be bonded to the anode gas diffusion layer 16a and the cathode gas diffusion layer 16c.

  The adhesive 46 is provided on the upstream side (air supply port side) of the refrigerant flow path 24 provided in the cathode side separator 18c, and adheres to the frame member 42, the cathode side separator 18c, and the cathode gas diffusion layer 16c. . The adhesive 48 is provided on the downstream side (air discharge port side) of the refrigerant flow path 24 provided in the cathode side separator 18c, and adheres to the frame member 42, the cathode side separator 18c, and the cathode gas diffusion layer 16c. . The adhesive 46 and the adhesive 48 adhere the cathode side separator 18c and the frame member 42 at the recess 32 (see FIG. 1) of the cathode side separator 18c. On the other hand, in the recess 30 (see FIG. 1) of the cathode side separator 18c, the cathode side separator 18c and the frame member 42 are separated from each other, and thus are not bonded by the adhesive 46 and the adhesive 48. In addition, the peripheral member 70 (refer FIG. 1) arrange | positioned at the both sides of the cathode side separator 18c may be directly joined to the frame member 42, and may be adhere | attached with the adhesive agent.

  The adhesive 44 and the adhesive 46 are thermoplastic resins such as polypropylene or polyethylene in which a silane coupling agent is blended, or a modified polyolefin in which a functional group is introduced into polyolefin, but may be thermosetting resins. The adhesive 48 is obtained by adding a heat conductive filler to a thermoplastic resin such as a modified olefin resin or a thermosetting resin. Examples of the heat conductive filler include aluminum nitride, alumina, boron nitride, zinc oxide, magnesium oxide, carbon nanotube (CNT: Carbon Nanotube), diamond, graphite, and graphene. The adhesive 48 includes at least one kind of such a heat conductive filler, so that the thermal conductivity is higher than that of the adhesive 44 and the adhesive 46.

  The frame member 42 is made of a resin such as polyethylene naphthalate (PEN). The frame member 42 may be formed of other insulating members as long as it has insulating properties. Since the frame member 42 has insulation, insulation between the anode and the cathode is ensured.

  According to Example 1, as shown in FIG. 2, the adhesive 48 that adheres to the cathode separator 18 c on the downstream side (air discharge port side) of the refrigerant flow path 24 contains the heat conductive filler and has a thermal conductivity. It is getting bigger. That is, the seal member 40 disposed around the MEGA 20 has a thermal conductivity of a portion in contact with the cathode separator 18 c on the downstream side (air discharge port side) of the refrigerant flow path 24 on the upstream side (air supply port side). It is larger than the thermal conductivity of the portion in contact with the side separator 18c. In addition, in the sealing member 40, the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16 c on the downstream side of the coolant channel 24 is larger than the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16 c on the upstream side. Thus, as shown in FIG. 2, on the downstream side of the refrigerant flow path 24, a path for directly radiating heat from the cathode gas diffusion layer 16c to the cathode side separator 18c as a heat dissipation path for heat generated by the electrochemical reaction in the cathode catalyst layer 14c. In addition to (black arrow I), a path for radiating heat from the cathode gas diffusion layer 16c to the cathode separator 18c via the adhesive 48 (black arrow II) and a path for radiating heat directly from the adhesive 48 to the outside (black arrow III) Occurs. Since the temperature of the air flowing through the refrigerant flow path 24 rises due to the heat generated in the cathode catalyst layer 14c, the temperature of the portion of the MEA 10 located on the downstream side of the refrigerant flow path 24 rises, resulting in a decrease in power generation performance. There are things to do. However, in the first embodiment, as described with reference to FIG. 2, the heat release path for the heat generated in the cathode catalyst layer 14 c increases on the downstream side of the refrigerant flow path 24, so the downstream side of the refrigerant flow path 24 in the MEA 10. The rise in the temperature of the part located in is suppressed. Therefore, a decrease in power generation performance can be suppressed.

  In Example 1, in place of or in addition to the adhesive 48 on the cathode side, in addition to the adhesive 48, a heat conductive filler is added to a portion of the anode side adhesive 44 located on the downstream side of the coolant channel 24. You may let them. As shown in FIG. 2, the anode-side adhesive 44 is in contact with the cathode gas diffusion layer 16c. Thereby, in the part located in the downstream of the refrigerant | coolant flow path 24 among MEA10, the heat | fever which generate | occur | produces in the cathode catalyst layer 14c can be thermally radiated effectively, and a temperature rise can be suppressed. As described above, the seal member 40 has a thermal conductivity at a portion in contact with the cathode separator 18c on the downstream side of the refrigerant flow path 24 higher than that at a portion in contact with the cathode separator 18c on the upstream side. It is only necessary to satisfy at least one of the fact that the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16c on the downstream side of the passage 24 is larger than the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16c on the upstream side.

  In the first embodiment, the case where the seal member 40 is configured by a plurality of members including the frame member 42 and the adhesive 44 to the adhesive 48 has been described as an example, but the seal member 40 may be formed of a single member. Good. In this case, on both the anode side and the cathode side, the thermal conductivity of the portion of the seal member 40 located on the downstream side of the refrigerant flow path 24 is larger than the thermal conductivity of the portion located on the upstream side.

  FIG. 3 is a cross-sectional view of a single cell 200 constituting the fuel cell according to the second embodiment. As shown in FIG. 3, in the single cell 200 of Example 2, the adhesive 50 provided on the cathode side on the downstream side (air exhaust port side) of the refrigerant flow path 24 is the same as the adhesive 44 provided on the anode side. Similarly, it consists of resin which does not contain a heat conductive filler. On the other hand, the adhesive 52 provided on the upstream side (air supply port side) of the refrigerant flow path 24 on the cathode side is made of a resin containing a heat insulating filler. Examples of the heat insulating filler include hollow glass beads. Since the adhesive 52 includes such a heat insulating filler, the thermal conductivity is smaller than that of the adhesive 44 and the adhesive 50.

  The cathode separator 18 c is provided with a through hole 60 in a portion located on the upstream side of the refrigerant flow path 24. FIG. 4 is a perspective view of the cathode-side separator 18c in the second embodiment. As shown in FIG. 4, the through hole 60 is provided on the upstream side of the coolant channel 24 so as to penetrate the bottom surface of the recess 32 that forms the coolant channel 24. The through holes 60 are provided in all of the plurality of refrigerant channels 24, for example, but may be provided only in a part. A plurality of through holes 60 may be provided in each refrigerant flow path 24. Moreover, the through-hole 60 may be provided in the part corresponded to the upstream of the refrigerant | coolant flow path 24 among the peripheral members 70 arrange | positioned at the both sides of the cathode side separator 18c. Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

  According to the second embodiment, as shown in FIG. 3, the adhesive 52 that adheres to the cathode separator 18 c on the upstream side (air supply port side) of the refrigerant flow path 24 contains a heat insulating filler and has a thermal conductivity. It is getting smaller. That is, the seal member 40 disposed around the MEGA 20 has a thermal conductivity of a portion in contact with the cathode separator 18 c on the upstream side (air supply port side) of the refrigerant flow path 24 on the downstream side (air discharge port side). It is smaller than the thermal conductivity of the portion in contact with the side separator 18c. In addition, in the sealing member 40, the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16c on the upstream side of the refrigerant flow path 24 is smaller than the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16c on the downstream side. Accordingly, heat generated by the electrochemical reaction in the cathode catalyst layer 14 c on the upstream side of the refrigerant flow path 24 is suppressed from radiating from the cathode gas diffusion layer 16 c to the cathode side separator 18 c via the adhesive 52. The temperature of the portion of the MEA 10 located upstream of the refrigerant flow path 24 is lowered by the air flowing through the refrigerant flow path 24, and as a result, the power generation performance may be reduced. However, in Example 2, since the heat generated in the cathode catalyst layer 14c is suppressed from radiating to the cathode separator 18c via the adhesive 52 on the upstream side of the refrigerant flow path 24, the refrigerant in the MEA 10 A decrease in the temperature of the portion located on the upstream side of the flow path 24 is suppressed. Therefore, a decrease in power generation performance can be suppressed.

  Further, according to the second embodiment, the through hole 60 is provided in the cathode separator 18 c on the upstream side of the refrigerant flow path 24. Thereby, in the upstream of the refrigerant | coolant flow path 24, it is suppressed that the heat | fever transmitted to the cathode side separator 18c via the cathode gas diffusion layer 16c is transmitted from the electric power generation area | region to the outer side of an electric power generation area | region. Therefore, it is possible to further suppress the temperature decrease of the portion of the MEA 10 located on the upstream side of the refrigerant flow path 24.

  In Example 2, the adhesive 48 containing the heat conductive filler of Example 1 may be used for the adhesive provided on the cathode side downstream of the refrigerant flow path 24.

  In addition, although Example 1 and Example 2 demonstrated the case of the air-cooled fuel cell as an example, the case of a water-cooled fuel cell may be sufficient. However, in an air-cooled fuel cell, the temperature distribution of the refrigerant tends to increase in the upstream area and the downstream area of the refrigerant flow path. For this reason, it is preferable to apply the present invention to an air-cooled fuel cell.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Membrane electrode assembly 12 Electrolyte membrane 14a Anode catalyst layer 14c Cathode catalyst layer 16a Anode gas diffusion layer 16c Cathode gas diffusion layer 18a Anode side separator 18c Cathode side separator 20 Membrane electrode gas diffusion layer assembly 22 Oxidant gas flow path 24 Refrigerant Flow path 26 Fuel gas flow path 30, 32 Recess 40 Seal member 42 Frame member 44-52 Adhesive 60 Through hole 70 Peripheral member

Claims (1)

A membrane electrode gas diffusion layer assembly comprising a membrane electrode assembly and an anode gas diffusion layer and a cathode gas diffusion layer disposed across the membrane electrode assembly;
A seal member disposed around the membrane electrode gas diffusion layer assembly;
An anode-side separator and a cathode-side separator that sandwich the membrane electrode gas diffusion layer assembly and the seal member,
The cathode-side separator has a refrigerant flow path through which a refrigerant for cooling the membrane electrode assembly flows on a surface opposite to the membrane electrode gas diffusion layer assembly.
The seal member has a thermal conductivity at a portion in contact with the cathode separator on the downstream side of the refrigerant flow path that is greater than a thermal conductivity of a portion on the upstream side of the refrigerant flow path in contact with the cathode separator, and / or Alternatively, the fuel cell has a thermal conductivity of a portion in contact with the cathode gas diffusion layer on the downstream side of the refrigerant flow path that is greater than a thermal conductivity of a portion in contact with the cathode gas diffusion layer on the upstream side of the refrigerant flow path.

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