JP6859892B2 - Fuel cell - Google Patents

Description

The present invention relates to a fuel cell.

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

Japanese Unexamined Patent Publication No. 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 due to an electrochemical reaction, the temperature of the refrigerant flowing through the refrigerant flow path rises due to this heat generation. Therefore, the temperature of the refrigerant on the downstream side is higher than the temperature of the refrigerant on the upstream side of the refrigerant flow path.

The membrane electrode assembly has good power generation performance when it is within an appropriate temperature range, and the power generation performance deteriorates even if it 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 is downstream. The side location may be higher than the appropriate temperature range. In this case, the power generation performance deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress a decrease in power generation performance.

The present invention comprises a membrane electrode gas diffusion layer junction including an anode gas diffusion layer and a cathode gas diffusion layer arranged with the membrane electrode junction sandwiched between the membrane electrode junction and the membrane electrode gas diffusion layer junction. A seal member arranged around the membrane electrode gas diffusion layer junction and an anode-side separator and a cathode-side separator that sandwich the seal member are provided, and the cathode-side separator is the membrane electrode gas diffusion layer junction. The surface opposite to the one has a refrigerant flow path through which a refrigerant for cooling the membrane electrode joint body flows, and the seal member is a frame member surrounding the membrane electrode gas diffusion layer joint body and the frame member. Of the adhesive which contains an adhesive to be adhered and whose thermal conductivity of the adhesive which adheres to the cathode side separator on the downstream side of the refrigerant flow path adheres to the cathode side separator on the upstream side of the refrigerant flow path. greater than the thermal conductivity, and / or adhesion to the cathode gas diffusion layer thermal conductivity of the adhesive adhering to the cathode gas diffusion layer downstream of the refrigerant flow path on the upstream side of the coolant channel A fuel cell having a higher thermal conductivity than that of the adhesive.

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

Hereinafter, examples of the present invention will be described with reference to the drawings.

The fuel cell of Example 1 is a polymer electrolyte fuel cell that generates electricity by receiving a fuel gas (for example, hydrogen) and an oxidant gas (for example, air) as reaction gases, and has a stack structure in which a large number of single cells are laminated. Has. 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 arranged around the MEGA 20. In other words, the MEGA 20 is arranged 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 blocking property and electron conductivity, and is formed of, for example, a carbon member such as dense carbon obtained by compressing carbon to make it gas impermeable, 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 holes s2, and the peripheral members 70 arranged on both sides of the cathode-side separator 18c have holes c1 and holes c2. It is provided. The peripheral member 70 is an insulating member such as a thermoplastic resin or a thermosetting resin. The holes a1, the holes s1 and the holes c1 communicate with each other to define a supply manifold for supplying hydrogen. The holes a2, s2, and c2 communicate with each other to define a discharge manifold for discharging hydrogen. On the surface of the anode-side separator 18a on the MEGA 20 side, a fuel gas flow path 26 extending from the supply manifold toward the discharge manifold and through which hydrogen supplied to the MEGA 20 flows is provided. The peripheral member 70 may be made of the same material as the cathode side separator 18c. That is, the cathode side separator 18c may include a peripheral member 70.

At least the portion of the cathode side separator 18c facing the MEGA 20 is formed by a member having gas blocking property and electron conductivity. The cathode side separator 18c is made of a metal member such as stainless steel whose uneven shape is formed by bending by press molding, for example. The cathode side separator 18c is formed with an oxidant gas flow path 22 and a refrigerant flow path 24 through which air flows, respectively, due 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 to the other end of the cathode side separator 18c, and are arranged 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 is mainly used for power generation. The refrigerant flow path 24 is formed by a recess 32 provided on the surface of the cathode side separator 18c opposite to the MEGA 20 and opened on the side opposite to the MEGA 20. Therefore, the air flowing through the refrigerant flow path 24 is mainly used for cooling the MEGA 20. As described above, the fuel cell of the first embodiment is an air-cooled fuel cell.

FIG. 2 is a cross-sectional view taken along the line AA of 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 14a is provided on one surface of the electrolyte membrane 12, and the cathode catalyst layer 14c is provided on the other surface of the electrolyte membrane 12. As a result, a membrane electrode assembly (MEA) 10 is formed. The electrolyte membrane 12 is, for example, a solid polymer membrane formed of 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 (carbon black or the like) carrying a catalyst (platinum or platinum-cobalt alloy or the like) for advancing an electrochemical reaction, and a solid polymer having a sulfonic acid group. Includes ionomers, which have good proton conductivity in wet conditions.

The anode gas diffusion layer 16a and the cathode gas diffusion layer 16c are provided on both sides of the MEA10 with the MEA10 interposed therebetween. The anode gas diffusion layer 16a and the cathode gas diffusion layer 16c are formed of a member 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 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 an adhesive 44 to an adhesive 48. The frame member 42 is provided so as to surround the circumference of the MEGA 20. The adhesive 44 is provided by adhering to the frame member 42, the anode side separator 18a, and the MEA 10 and surrounding the periphery of the fuel gas flow path 26. As a result, the hydrogen flowing through the fuel gas flow path 26 is sealed so as not to leak to the outside. The adhesive 44 may be adhered 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 on 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 on 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, since the cathode side separator 18c and the frame member 42 are separated from each other, they are not adhered by the adhesive 46 and the adhesive 48. The peripheral members 70 (see FIG. 1) arranged on both sides of the cathode side separator 18c may be directly bonded to the frame member 42 or may be bonded with an adhesive.

The adhesive 44 and the adhesive 46 are thermoplastic resins such as polypropylene or polyethylene containing a silane coupling agent and modified polyolefin in which a functional group is introduced into polyolefin, but may be thermosetting resins. The adhesive 48 is a thermoplastic resin such as a deformed olefin resin or a thermosetting resin to which a heat transfer filler is added. Examples of the heat transfer filler include aluminum nitride, alumina, boron nitride, zinc oxide, magnesium oxide, carbon nanotubes (CNT), diamond, graphite, graphene and the like. The adhesive 48 contains at least one such heat-conducting filler, so that the adhesive 48 has a higher thermal conductivity than the adhesive 44 and the adhesive 46.

The frame member 42 is made of, for example, a resin such as polyethylene naphthalate (PEN). The frame member 42 may be made of any other insulating member as long as it has an insulating property. Since the frame member 42 has an insulating property, the insulating property between the anode and the cathode is ensured.

According to the first embodiment, as shown in FIG. 2, the adhesive 48 that adheres to the cathode side separator 18c on the downstream side (air discharge port side) of the refrigerant flow path 24 contains a heat conductive filler and has a thermal conductivity. It's getting bigger. That is, in the seal member 40 arranged around the MEGA 20, the thermal conductivity of the portion in contact with the cathode side separator 18c on the downstream side (air discharge port side) of the refrigerant flow path 24 is the cathode 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. Moreover, in the seal member 40, the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16c on the downstream side of the refrigerant flow path 24 is larger than the thermal conductivity of the portion in contact with the cathode gas diffusion layer 16c on the upstream side. As a result, as shown in FIG. 2, 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 on the downstream side of the refrigerant flow path 24. In addition to (black arrow I), a path for radiating heat from the cathode gas diffusion layer 16c to the cathode side 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 by 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, and as a result, the power generation performance deteriorates. I have something to do. However, in the first embodiment, as described with reference to FIG. 2, since the heat dissipation path of the heat generated in the cathode catalyst layer 14c increases on the downstream side of the refrigerant flow path 24, the downstream side of the refrigerant flow path 24 in the MEA10 The temperature rise of the part located in is suppressed. Therefore, deterioration of power generation performance can be suppressed.

In Example 1, instead of the adhesive 48 on the cathode side or in addition to the adhesive 48, a heat transfer filler is added to a portion of the adhesive 44 on the anode side located on the downstream side of the refrigerant flow path 24. You may let me. As shown in FIG. 2, the adhesive 44 on the anode side is in contact with the cathode gas diffusion layer 16c. As a result, the heat generated in the cathode catalyst layer 14c can be effectively dissipated and the temperature rise can be suppressed in the portion of the MEA 10 located on the downstream side of the refrigerant flow path 24. As described above, in the sealing member 40, the thermal conductivity of the portion in contact with the cathode side separator 18c on the downstream side of the refrigerant flow path 24 is larger than the thermal conductivity of the portion in contact with the cathode side separator 18c on the upstream side, and the refrigerant flow. It suffices 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 path 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 composed of a plurality of members of the frame member 42 and the adhesive 44 to the adhesive 48 is shown as an example, but even if the seal member 40 is formed of one 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 the second embodiment, the adhesive 50 provided on the downstream side (air discharge port side) of the refrigerant flow path 24 on the cathode side is the adhesive 44 provided on the anode side. Similarly, it is made of a resin that does not contain a heat transfer 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. By containing such a heat insulating filler, the adhesive 52 has a lower thermal conductivity than the adhesive 44 and the adhesive 50.

Further, the cathode side separator 18c 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 so as to penetrate the bottom surface of the recess 32 forming the refrigerant flow path 24 on the upstream side of the refrigerant flow path 24. The through holes 60 are provided in all of the plurality of refrigerant flow paths 24, for example, but may be provided only in a part thereof. Further, a plurality of through holes 60 may be provided in each refrigerant flow path 24. Further, the through hole 60 may be provided in a portion of the peripheral member 70 arranged on both sides of the cathode side separator 18c, which corresponds to the upstream side of the refrigerant flow path 24. Since other configurations are the same as those in the first embodiment, the description thereof will be omitted.

According to the second embodiment, as shown in FIG. 3, the adhesive 52 that adheres to the cathode side separator 18c 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's getting smaller. That is, in the seal member 40 arranged around the MEGA 20, the thermal conductivity of the portion in contact with the cathode side separator 18c on the upstream side (air supply port side) of the refrigerant flow path 24 is the cathode 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. Moreover, in the seal 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. As a result, on the upstream side of the refrigerant flow path 24, heat generated by the electrochemical reaction in the cathode catalyst layer 14c is suppressed from being dissipated from the cathode gas diffusion layer 16c to the cathode side separator 18c via the adhesive 52. The temperature of the portion of the MEA 10 located on the upstream side 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 lowered. However, in the second embodiment, the heat generated in the cathode catalyst layer 14c is suppressed from being dissipated to the cathode side separator 18c via the adhesive 52 on the upstream side of the refrigerant flow path 24, so that the refrigerant in the MEA 10 is used. The decrease in temperature of the portion located on the upstream side of the flow path 24 is suppressed. Therefore, deterioration of power generation performance can be suppressed.

Further, according to the second embodiment, a through hole 60 is provided in the cathode side separator 18c on the upstream side of the refrigerant flow path 24. As a result, on the upstream side of the refrigerant flow path 24, the heat transferred to the cathode side separator 18c via the cathode gas diffusion layer 16c is suppressed from being transferred from the power generation region to the outside of the power generation region. Therefore, it is possible to further suppress the decrease in temperature 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-conducting filler of Example 1 may be used as the adhesive provided on the cathode side on the downstream side of the refrigerant flow path 24.

In the first and second embodiments, the case of an air-cooled fuel cell has been described as an example, but a water-cooled fuel cell may also be used. However, in an air-cooled fuel cell, the temperature distribution of the refrigerant in the upstream region and the downstream region of the refrigerant flow path tends to be large. Therefore, it is preferable to apply the present invention to an air-cooled fuel cell.

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

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 Oxidizer gas flow path 24 Refrigerator Flow path 26 Fuel gas flow path 30, 32 Recesses 40 Seal member 42 Frame member 44 to 52 Adhesive 60 Through hole 70 Peripheral member

Claims (1)

A membrane electrode gas diffusion layer assembly including an anode gas diffusion layer and a cathode gas diffusion layer arranged so as to sandwich the membrane electrode assembly and the membrane electrode assembly.
A sealing member arranged around the membrane electrode gas diffusion layer joint and
The membrane electrode gas diffusion layer joint and the anode-side separator and the cathode-side separator that sandwich the seal member are provided.
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, the membrane electrode and the frame member surrounding the gas diffusion layer assembly comprises an adhesive which adheres to the frame member, the adhesive adhering to the cathode-side separator downstream of the coolant channel Is greater than the thermal conductivity of the adhesive that adheres to the cathode side separator on the upstream side of the refrigerant flow path and / or adheres to the cathode gas diffusion layer on the downstream side of the refrigerant flow path. A fuel cell in which the thermal conductivity of the adhesive is larger than the thermal conductivity of the adhesive that adheres to the cathode gas diffusion layer on the upstream side of the refrigerant flow path.

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