JP2009176490A - Fuel cell and fuel cell separator - Google Patents

Abstract

When a porous separator is used in a fuel cell, the ability to humidify an introduced gas from a cooling water passage is enhanced.
Each of the unit cells is formed of a porous material having a groove disposed adjacent to the fuel electrode and forming a fuel gas flow path 5 for supplying fuel gas to the fuel electrode. The first separator plate 13 is formed of a porous material having a groove which is disposed adjacent to the oxidant electrode and forms an oxidant gas flow path 6 for supplying an oxidant gas to the oxidant electrode. Second separator plate 14. In the fuel cell stack, the first separator plate 13 and the second separator plate 14 of the unit cells adjacent to each other are provided with grooves that form a part of the cooling water flow path at both positions facing each other. The cooling water flow path 12 is configured by combining these grooves.
[Selection] Figure 5

Description

  The present invention relates to a fuel cell having a laminate in which unit cells are laminated, and a separator incorporated in the fuel cell.

  In a fuel cell system using a polymer electrolyte membrane having proton conductivity as an electrolyte, a fuel gas containing hydrogen (anode reaction gas) is supplied to the fuel electrode (anode electrode) and an oxidant gas containing oxygen (cathode reaction). Gas) is supplied to the oxidant electrode (cathode electrode) to generate electricity. In that case, fuel gas and oxidant gas are supplied along the gas flow path provided in the separator with respect to the layered fuel electrode, the solid polymer electrolyte membrane, and the oxidant electrode. The gas flow path communicates with the gas supply / discharge manifold and the gas return manifold, and the fuel gas and the oxidant gas are supplied from the gas supply section of the gas supply / discharge manifold through the gas return manifold and from the upstream of the gas flow path. It flows downstream and is discharged to the outside from the gas discharge portion of the gas supply / discharge manifold. The battery reaction consumes hydrogen in the fuel gas and oxygen in the oxidant gas, and the reaction product water is discharged as water vapor.

  On the other hand, the solid polymer electrolyte membrane has a characteristic that the moisture content of the membrane changes due to the equilibrium water vapor pressure, and the resistance of the electrolyte membrane changes, and in order to reduce the resistance of the electrolyte membrane and obtain sufficient power generation performance, It is necessary to add moisture to the polymer electrolyte membrane, that is, humidification. There are two types of humidification: an external humidification method in which water vapor is added to the fuel gas or oxidant gas in advance, and an internal humidification method in which water is directly added via a separator.

  This polymer electrolyte fuel cell stack is generally configured by inserting a separator for each unit cell. This separator has a cooling and heat removal function for removing heat generated by the unit battery power generation, a conductive function for electrically connecting the unit cells in series, and the separator side of one unit cell disposed via the separator. Reactive gas blocking function to prevent mixing through the fuel gas or oxidant gas flowing through the separator and the separator of the other unit cell disposed through the separator through the oxidant gas or fuel gas separator have. In addition, it has mechanical strength capable of maintaining its shape under a predetermined lamination tightening.

  These separators form a reaction gas channel for supplying fuel gas (or oxidant gas) to the unit cell reaction surface on one side, and a channel for circulating cooling water on the other side. The formed plate and the plate formed with the reaction gas channel for supplying the oxidant gas (or fuel gas) to the unit cell reaction surface only on one surface are integrated with the cooling water channel forming surface and the flat surface as the adhesive surface. Generally, it is formed.

  Moreover, although the metal system represented by patent document 1 is proposed as a material of a separator, generally the separator which has a carbonaceous or graphitic carbon material as a main component is used from a durable point. .

  A separator mainly composed of carbonaceous material or graphite is used by being fixed to a resin having a function of adhering and binding those powder particles and forming a plate. As the resin having an adhesion / binding function, a phenol resin, a thermosetting resin typified by an epoxy resin, or a thermoplastic resin typified by a polyphenylene resin (PPS) is generally used. Furthermore, a separator obtained by high-temperature treatment (carbonization treatment or graphitization treatment) of the plate is used for the purpose of improving durability and improving electrical conductivity.

  This separator mainly composed of carbonaceous or graphite is generally mixed with the above-mentioned carbonaceous or graphite powder by using a thermosetting resin as an adhesive / binder from the viewpoint of cost and reliability of physical properties. It is formed from a plate obtained by hot pressing the kneaded material. In addition, in order to satisfy the above separator function, this mixed and kneaded product is a molding aid such as 90% by weight or more of carbonaceous or graphite powder, 10% by weight or less of thermosetting resin (and curing agent), and internal release agent. What has a composition with an agent is used.

  In addition, in the fuel cell described in Patent Document 2, a porous separator having a function of humidifying a reaction gas and a function of removing condensed product water in a unit cell in addition to the function of the separator has been proposed.

  Regarding the porous separator, in the fuel cell described in Patent Document 3, the separator on the side in contact with at least one side of the fuel electrode and the oxidant electrode is increased, and the porosity on the other side is decreased. Proposed.

In a normal polymer electrolyte fuel cell, a humidifier for humidifying the reaction gas introduced into the fuel cell is required. When a porous separator is used, the humidifier is used because the porous separator has a function of humidifying. Is no longer necessary.
JP 2003-193206 A Japanese Patent Publication No. 7-95447 JP-A-2005-142015

  In the case of a normal separator, either the fuel electrode and cooling water, or the oxidant electrode and cooling water are arranged on both sides of the separator. And the cooling water separator is adhere | attached on the smooth surface of the separator by which the gas flow path was distribute | arranged to the single side | surface. However, in this configuration, there is an adhesive or the like at a position corresponding to the back of the gas introduction portion supplied to the separator on one side. Since the adhesive and the adhesive sheet usually exhibit water repellency, the porous separator also exhibits water repellency, and water transfer / permeability and humidification performance are reduced. As a result, humidification of the introduced gas becomes insufficient, resulting in damage to the polymer film and a decrease in battery performance.

  An object of the present invention is to increase the humidification ability from the cooling water flow path to the introduced gas when a porous separator is employed in the fuel cell.

  In order to achieve the above object, in one aspect of the fuel cell according to the present invention, in the fuel cell having a laminate in which a plurality of unit cells are stacked, each of the unit cells includes an electrolyte membrane and an electrolyte membrane. A fuel electrode and an oxidizer electrode arranged adjacent to the electrolyte membrane with both sides interposed therebetween, and a fuel gas flow path arranged adjacent to the fuel electrode for supplying fuel gas to the fuel electrode are formed. And a first separator plate formed of a porous material having a groove for forming an oxidant gas flow path disposed adjacent to the oxidant electrode and supplying an oxidant gas to the oxidant electrode. A second separator plate having a groove to be formed and formed of a porous material, and the first separator plate and the second separator plate of the unit cells adjacent to each other on the surfaces adjacent to each other. Oppose Has a groove which forms part of both the cooling water passage position, the cooling water passage Together, these grooves can be configured, and wherein.

  In another aspect of the fuel cell according to the present invention, in the fuel cell having a laminate in which a plurality of unit cells are stacked, each of the unit cells sandwiches the electrolyte membrane and both surfaces of the electrolyte membrane. And a fuel electrode and an oxidant electrode disposed adjacent to the electrolyte membrane, and a groove disposed adjacent to the fuel electrode and forming a fuel gas passage for supplying fuel gas to the fuel electrode. A first separator plate formed of a porous material, and a groove that is disposed adjacent to the oxidant electrode and forms an oxidant gas flow path for supplying an oxidant gas to the oxidant electrode. And a second separator plate formed of a porous material, and a cooling water flow on at least one of the surfaces of the unit cells adjacent to each other where the first separator plate and the second separator plate are adjacent to each other. The road An adhesive is applied to the side surfaces of the first separator plate and the second separator plate of the unit cells adjacent to each other, and the first separator plate and the second separator are formed by the adhesive. The plate is joined to each other.

  The fuel cell separator according to the present invention is a fuel cell separator constituting a part of each unit cell in a fuel cell having a laminate in which a plurality of unit cells are stacked, and the first surface of the electrolyte membrane. A groove formed adjacent to a surface of the fuel electrode disposed adjacent to the first surface of the electrolyte membrane and forming a fuel gas flow path for supplying fuel gas to the fuel electrode. And a first separator plate formed of a porous material and a second separator layer of the oxidizer electrode disposed adjacent to the first surface opposite to the first surface of the electrolyte membrane. A second separator formed of a porous material having a groove which is disposed adjacent to a surface opposite to the surface and forms an oxidant gas flow path for supplying an oxidant gas to the oxidant electrode. And the first separator of the unit cells adjacent to each other The rate and the second separator plate have grooves that form a part of the cooling water flow path at both positions on the mutually adjacent surfaces, and the cooling water flow path is formed by combining these grooves. It is characterized by being comprised.

  According to the present invention, when a porous separator is employed in a fuel cell, the ability to humidify the introduced gas from the cooling water channel can be increased.

  Embodiments of a fuel cell and a fuel cell separator according to the present invention will be described below with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a partial vertical cross-sectional view of a fuel cell stack according to a first embodiment of the present invention, and is a cross-sectional view taken along line II in FIG. FIG. 2 is a plan sectional view of the fuel cell according to the first embodiment of the present invention. FIG. 3 is a partially enlarged sectional view of two separator plates adjacent to each other in the fuel cell stack of FIG. 1, and is a sectional view taken along line III-III in FIG.

  As shown in FIG. 1, in the fuel cell according to this embodiment, a fuel electrode 1 and an oxidant electrode 2 are arranged across a solid polymer electrolyte membrane 3 having proton conductivity. The outer side of the fuel electrode 1 and the oxidant electrode 2 is further sandwiched by the separator 4. The separator 4 includes a first separator plate 13 adjacent to the fuel electrode 1 and a second separator plate 14 adjacent to the oxidant electrode 2. One unit cell 40 is constituted by the solid polymer electrolyte membrane 3, the fuel electrode 1 and the oxidant electrode 2 sandwiching the solid polymer electrolyte membrane 3, and the first separator plate 13 and the second separator plate 14 sandwiching them. A plurality of unit cells 40 are stacked to constitute the fuel cell stack 11.

  A groove for forming the fuel gas channel 5 is formed at a position adjacent to the fuel electrode 1 of the first separator plate 13, and the oxidant gas channel 6 is positioned at a position adjacent to the oxidant electrode 2 of the second separator plate 14. Grooves for forming are formed. Further, a groove for forming the cooling water flow path 12 is formed at a position of the second separator plate 14 adjacent to the first separator plate 13. Further, an end seal sheet fixing step 15 is formed on the same surface of the second separator plate 14 as the oxidant gas flow path 6.

  As shown in FIG. 2, six manifolds extending in the stacking direction are formed on the side surface of the fuel cell stack 11, and each manifold communicates with a specific gas channel or cooling water channel of each unit cell. .

  That is, the fuel gas supply manifold 8a communicates with the fuel gas flow path 5, from which fuel gas containing hydrogen is supplied. The fuel gas discharge manifold 8b is disposed on the opposite side of the fuel gas supply manifold 8a and communicates with the fuel gas flow path 5, from which fuel gas is discharged. The oxidant gas supply manifold 9a communicates with the oxidant gas flow path 6, from which oxidant gas containing oxygen is supplied. The oxidant gas discharge manifold 9b is disposed on the opposite side of the oxidant gas supply manifold 9a and communicates with the oxidant gas flow path 6, from which the oxidant gas is discharged. The cooling water supply manifold 10a communicates with the cooling water flow path 12, from which cooling water as a cooling medium is supplied. The cooling water discharge manifold 10b is disposed on the opposite side of the cooling water supply manifold 10a and communicates with the cooling water flow path 12, from which the cooling water is discharged.

  The battery reaction consumes hydrogen in the fuel gas and oxygen in the oxidant gas, and the reaction product water is discharged as water vapor.

  The separator 4 includes a cooling heat removal function for removing heat generated by the unit battery power generation, a conductive function for electrically connecting the unit cells in series, and a fuel gas of the unit cells adjacent to each other via the separator. It has a reactive gas blocking function to prevent mixing of oxidant gas. In addition, it has mechanical strength capable of maintaining its shape under a predetermined lamination tightening.

  The material of the separator 4 is mainly composed of a carbonaceous or graphitic carbon material, for example. The separator 4 mainly composed of carbonaceous material or graphite material may be used by fixing it with a resin having a function of adhering and binding those powder particles and forming a plate. As the resin having an adhesion / binding function, a phenol resin, a thermosetting resin typified by an epoxy resin, or a thermoplastic resin typified by a polyphenylene resin can be used. The plate may be subjected to high-temperature treatment (carbonization treatment or graphitization treatment) for the purpose of improving durability and electrical conductivity. The separator 4 mainly composed of carbonaceous or graphite is mixed and kneaded with carbonaceous or graphite powder using a thermosetting resin as an adhesive / binder from the viewpoint of cost and reliability of physical properties. The material may be formed from a hot-pressed plate.

  As shown in FIGS. 1 and 3, the first separator plate 13 and the second separator plate 14 of the two unit cells 40 adjacent to each other are bonded together, so that the cooling water flow path 12 is formed between them. Yes. In the bonding, in this embodiment, an adhesive or an adhesive sheet 23 is bonded to the side surface, and no adhesive is applied to the bonding surface.

  With this configuration, in the present embodiment, it is possible to prevent the water-repellent adhesive from obstructing the movement when the water in the cooling water flow path 12 moves to the fuel gas flow path 5 and the oxidant gas flow path 6. Thereby, it is possible to sufficiently humidify the reaction gas through the porous separator, and it is possible to suppress damage to the polymer film and deterioration of the battery performance.

[Second Embodiment]
FIG. 4 is a partially enlarged sectional view of two separator plates adjacent to each other in the fuel cell stack according to the second embodiment of the present invention. In this embodiment, a groove forming the cooling water flow path 12 is formed on the first separator plate 13 side. That is, the groove of the fuel gas flow path 5 is formed on one surface of the first separator plate 13, and the groove of the cooling water flow path 12 is formed on the opposite surface. On the second separator plate 14 side where the groove of the oxidant gas flow path 6 is formed, the groove of the fuel gas flow path 5 is not formed.

  Even in this case, similarly to the first embodiment, the first separator plate 13 and the second separator plate 14 are bonded together to form the cooling water flow path 12 therebetween. In this case, as in the first embodiment, since there is no adhesive on the bonding surface, the water repellency is generated when the water in the cooling water channel 12 moves to the fuel gas channel 5 and the oxidant gas channel 6. It is possible to avoid that the adhesive prevents the movement.

[Third Embodiment]
FIG. 5 is a partially enlarged sectional view of two separator plates adjacent to each other in the fuel cell stack according to the third embodiment of the present invention. In this embodiment, a groove that forms the cooling water flow path 12 is formed in both the first separator plate 13 and the second separator plate 14, and the first separator plate 13 and the second separator plate 14 are bonded together. Thus, a cooling water channel 12 is formed between them. In this case, in order to form the cooling water flow path 12, the groove formed in the first separator plate 13 and the groove formed in the second separator plate 14 are aligned, and the depth of each groove depends on the flow of the cooling water. Each half of the depth of the road 12 is assumed.

  In order to bond the first separator plate 13 and the second separator plate 14, as in the first and second embodiments, an adhesive or an adhesive sheet 23 is bonded to the side surface. Has no adhesive applied.

  In this embodiment, as in the first and second embodiments, the water-repellent adhesive moves when the water in the cooling water passage 12 moves to the fuel gas passage 5 and the oxidant gas passage 6. You can avoid it. Furthermore, in this embodiment, since the groove for the cooling water flow path 12 is formed in both the first separator plate 13 and the second separator plate 14, the fuel gas flow path 5 and the oxidant gas flow path 6 are provided. And the cooling water flow path 12 are relatively short, and the fuel gas and the oxidant gas can be sufficiently humidified.

[Fourth Embodiment]
FIG. 6 is a partially enlarged sectional view of two separator plates adjacent to each other in the fuel cell stack according to the fourth embodiment of the present invention. This embodiment is a modification of the third embodiment, and in order to bond the first separator plate 13 and the second separator plate 14, an adhesive 23 is applied to a part of the bonding surface. Yes. As described above, the normal adhesive 23 has water repellency, but a groove for the cooling water flow path 12 is formed in both the first separator plate 13 and the second separator plate 14 as in the third embodiment. Therefore, the distance from the cooling water flow path 12 to the fuel gas flow path 5 and the oxidant gas flow path 6 is relatively short, and the fuel gas and the oxidant gas can be sufficiently humidified.

[Other Embodiments]
Each embodiment described above is merely an example, and the present invention is not limited thereto. For example, the groove of the cooling water flow path 12 formed in the second separator plate 14 in the first embodiment (FIG. 3) and the first separator plate 13 in the second embodiment (FIG. 4). It is also possible to combine the grooves of the cooling water flow path 12 and not to align the positions of these grooves.

FIG. 3 is a partial vertical cross-sectional view of the fuel cell stack according to the first embodiment of the present invention, which is a cross-sectional view taken along the line I-I in FIG. 2. 1 is a cross-sectional plan view of a fuel cell according to a first embodiment of the present invention. FIG. 3 is a partially enlarged sectional view of two separator plates adjacent to each other in the fuel cell stack of FIG. 1, and is a sectional view taken along line III-III in FIG. It is a partial expanded sectional view of two separator plates adjacent to each other in the fuel cell stack according to the second embodiment of the present invention. FIG. 6 is a partially enlarged sectional view of two separator plates adjacent to each other in a fuel cell stack according to a third embodiment of the present invention. It is a partial expanded sectional view of two separator plates adjacent to each other in a fuel cell stack according to a fourth embodiment of the present invention.

Explanation of symbols

1: Fuel electrode (anode electrode)
2: Oxidant electrode (cathode electrode)
3: Solid polymer electrolyte membrane 4: Separator 5: Fuel gas flow path 6: Oxidant gas flow path 8a: Fuel gas supply manifold 8b: Fuel gas discharge manifold 9a: Oxidant gas supply manifold 9b: Oxidant gas discharge manifold 10a : Cooling water supply manifold 10b: Cooling water discharge manifold 11: Fuel cell stack 23: Adhesive (adhesive sheet)

Claims (5)

In a fuel cell having a laminate in which a plurality of unit cells are laminated,
Each of the unit cells is
An electrolyte membrane;
A fuel electrode and an oxidizer electrode disposed adjacent to the electrolyte membrane across both sides of the electrolyte membrane;
A first separator plate formed adjacent to the fuel electrode and formed of a porous material having a groove forming a fuel gas flow path for supplying fuel gas to the fuel electrode;
A second separator plate formed of a porous material having a groove disposed adjacent to the oxidant electrode and forming an oxidant gas flow path for supplying an oxidant gas to the oxidant electrode; ,
With
The first separator plate and the second separator plate of the unit cells adjacent to each other have grooves that form a part of the cooling water flow path at both positions facing each other on the adjacent surfaces. Together, the cooling water flow path is configured,
A fuel cell.   Adhesive is applied to the mutually opposing surfaces of the first separator plate and the second separator plate of the unit cells adjacent to each other, and the first separator plate and the second separator plate are joined to each other. The fuel cell according to claim 1, wherein:   Adhesive is applied to the side surfaces of the first separator plate and the second separator plate of the unit cells adjacent to each other, and the first separator plate and the second separator plate are joined to each other by the adhesive. The fuel cell according to claim 1, wherein: In a fuel cell having a laminate in which a plurality of unit cells are laminated,
Each of the unit cells is
An electrolyte membrane;
A fuel electrode and an oxidizer electrode disposed adjacent to the electrolyte membrane across both sides of the electrolyte membrane;
A first separator plate formed adjacent to the fuel electrode and formed of a porous material having a groove forming a fuel gas flow path for supplying fuel gas to the fuel electrode;
A second separator plate formed of a porous material having a groove disposed adjacent to the oxidant electrode and forming an oxidant gas flow path for supplying an oxidant gas to the oxidant electrode; ,
With
The first separator plate and the second separator plate of the unit cells adjacent to each other have a groove that forms a cooling water channel on at least one of the adjacent surfaces;
Adhesive is applied to the side surfaces of the first separator plate and the second separator plate of the unit cells adjacent to each other, and the first separator plate and the second separator plate are joined to each other by the adhesive. Being
A fuel cell. A fuel cell separator that constitutes a part of each unit cell in a fuel cell having a laminate in which a plurality of unit cells are laminated,
A fuel gas disposed adjacent to a surface opposite to the first surface of the electrolyte membrane of the fuel electrode disposed adjacent to the first surface of the electrolyte membrane to supply fuel gas to the fuel electrode A first separator plate having a groove for forming a flow path and formed of a porous material;
The oxidant electrode disposed adjacent to the surface opposite to the second surface of the electrolyte membrane of the oxidant electrode disposed adjacent to the first surface opposite to the first surface of the electrolyte membrane. A second separator plate formed of a porous material having a groove forming an oxidant gas flow path for supplying an oxidant gas to
With
The first separator plate and the second separator plate of the unit cells adjacent to each other have grooves that form a part of the cooling water flow path at both positions facing each other on the adjacent surfaces. The cooling water flow path is formed together,
A fuel cell separator.

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