JP2012150961A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress sealing performance deterioration due to a thermal expansion difference between an external manifold and a fuel cell laminate in an external manifold type fuel cell.SOLUTION: A fuel cell according to an embodiment includes single-cell batteries laminated and an external manifold. In the fuel cell, manifolds 30, 31, 32, 33 comprise a manifold material having a linear expansion coefficient lower than that of a separator, and the manifold material contains an insulating resin material; or an end plate comprises an end plate material having a linear expansion coefficient lower than that of the separator, and the end plate material contains an insulating resin material. The manifold material or the end plate material, for example, contains fillers in a thermosetting or thermoplastic insulating resin, the fillers being made of an inorganic material having a linear expansion coefficient lower than that of the insulating resin.

Description

  Embodiments described herein relate generally to a fuel cell including a stacked body in which a plurality of single cell batteries are stacked, and an external manifold disposed outside the stacked body.

  In a fuel cell using a proton-conducting solid polymer electrolyte membrane as an electrolyte, electric conduction in which gas flow passages are provided on both sides of a membrane electrode assembly (MEA) in which the electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode A single cell battery (unit battery) is configured by disposing a separator, and a plurality of single cell batteries are stacked to form a stacked body (fuel cell stack). Furthermore, both ends of the laminate are held by end plates, a plurality of studs are passed through holes penetrating both end plates, and the laminate is tightened via a spring (Patent Documents 1 and 2).

  It is necessary to uniformly supply the fuel (hydrogen) necessary for the reaction, the oxidant (air), and the cooling water necessary for cooling to each single cell battery of the fuel cell stack. There are two types of manifolds for distributing and collecting reaction gas and cooling water: an internal manifold system and an external manifold system.

  In the external manifold system, the gas flow path provided in the separator is extended to the end of the separator and opened on the side surface of the laminated body, and a separate external manifold is provided on the side surface for distribution. In the external manifold system, since the separator does not include a manifold, the size is equivalent to the effective area of the membrane electrode assembly, and the separator can be made compact, which is advantageous for cost reduction. In addition, inexpensive plastic with insulating properties can be used for the external manifold, and the cost increase can be minimized. The volume of the manifold can also be set without being restricted by the size of the separator, and gas and cooling water can be evenly distributed by the gas / cooling water flow passage of each single cell battery constituting the laminate.

  Here, a method for preventing the end plate from being corroded by gas containing water vapor and cooling water flowing through the external manifold by configuring the end plate with an insulating resin material has been proposed (for example, (See Patent Document 3).

  Further, as a method for improving the sealability between the external manifold and the laminate, a method of smoothing the side surface of the laminate has been proposed (see, for example, Patent Document 4).

JP 2006-40807 A JP 2008-218087 A JP 2007-179992 A JP 2008-10279 A

  Insulating resins used in the external manifold system generally have a large coefficient of linear expansion, and also have a large coefficient of linear expansion compared to carbon resins and metals used in separators constituting single cell batteries. For this reason, the internal dimension of the external manifold is larger than the external dimension of the single cell battery at 80 ° C., which is a general operating temperature of the polymer electrolyte fuel cell stack. As a result, there is a problem that a gap is generated between the external manifold and the side surface of the fuel cell stack, the sealing performance is lowered, and the reaction gas is liable to leak.

  Patent Document 1 discloses a method for preventing loosening by fastening an external manifold with two types of wires having positive and negative linear expansion coefficients. However, a method for eliminating the difference in thermal expansion caused by the material characteristics of the manifold and the single cell battery is not disclosed.

  In the case where the end plate is made of an insulating resin material, the insulating resin generally has a larger linear expansion coefficient than the carbon resin or metal used for the separator constituting the unit cell. For this reason, at 80 ° C, which is the general operating temperature of polymer electrolyte fuel cell stacks, the outer peripheral dimensions of the end plate are larger than the outer peripheral dimensions of the unit cells, and a gap is created between the outer manifold and the laminate seal. There exists a subject that sealing performance falls and it becomes easy for a reactive gas to leak.

  The problem to be solved by the present invention is to suppress deterioration in sealing performance due to a difference in thermal expansion between an external manifold or end plate and a fuel cell stack in an external manifold type fuel cell.

  In order to solve the above-described problem, one aspect of the fuel cell according to the present invention is a stacked body in which a plurality of single cell batteries are stacked in a predetermined stacking direction, and fuel gas is distributed to each of the plurality of single cell batteries. A fuel inlet manifold, an oxidant inlet manifold for delivering oxidant gas to each of the plurality of single cell batteries, a fuel outlet manifold for discharging fuel gas from each of the plurality of single cell batteries, and each of the plurality of single cell batteries. An oxidant outlet manifold for discharging oxidant gas from the fuel cell, and the fuel inlet manifold, the oxidant inlet manifold, the fuel outlet manifold, and the oxidant outlet manifold are in contact with a side surface of the stacked body and extend in the stacking direction. Each of the single cell batteries includes a membrane / electrode composite and a membrane / electrode composite. A separator that forms a fuel gas flow path and an oxidant gas flow path in contact with both sides of the membrane-electrode assembly across the body, and is configured to overlap in the stacking direction. Connected to a fuel inlet manifold, the fuel gas flow passage is connected to the fuel outlet manifold, the oxidant gas flow passage is connected to the oxidant inlet manifold, and the oxidant gas flow passage is connected to the oxidant outlet manifold. And at least one of the fuel inlet manifold, the fuel outlet manifold, the oxidant inlet manifold, and the oxidant outlet manifold is made of a manifold material having a linear expansion coefficient lower than that of the separator, and the manifold material is insulated. It contains the property resin material.

  Another aspect of the fuel cell according to the present invention is a laminate in which a plurality of single cell batteries are laminated in a predetermined lamination direction, and an insulating resin disposed at both ends of the laminate in the lamination direction. Two end plates made of a material, a fastening stud attached to the two end plates and tightening the end plates in a direction approaching each other, and fuel gas is distributed to each of the plurality of single cell batteries A fuel inlet manifold, an oxidant inlet manifold for delivering oxidant gas to each of the plurality of single cell batteries, a fuel outlet manifold for discharging fuel gas from each of the plurality of single cell batteries, and each of the plurality of single cell batteries. An oxidant outlet manifold for discharging an oxidant gas from the fuel inlet manifold, the oxidant inlet manifold, and the fuel outlet In the fuel cell in which the nihold and the oxidant outlet manifold are arranged so as to be in contact with the side surface of the stacked body and extend in the stacking direction, respectively, the single cell battery includes a membrane / electrode composite and a membrane / electrode composite. A separator that forms a fuel gas flow path and an oxidant gas flow path in contact with both sides of the membrane-electrode assembly across the body, and is configured to overlap in the stacking direction. Connected to a fuel inlet manifold, the fuel gas flow passage is connected to the fuel outlet manifold, the oxidant gas flow passage is connected to the oxidant inlet manifold, and the oxidant gas flow passage is connected to the oxidant outlet manifold. Connected, the end plate is composed of an end plate material having a linear expansion coefficient lower than that of the separator, Serial endplate material is characterized, by containing an insulating resin material.

  ADVANTAGE OF THE INVENTION According to this invention, the sealing performance fall by the thermal expansion difference of the external manifold or end plate in an external manifold type fuel cell and a fuel cell laminated body can be suppressed.

1 is a perspective view showing a first embodiment of a fuel cell according to the present invention. It is a perspective view which shows the laminated body of the fuel cell of FIG. It is a cross-sectional view of the fuel cell of FIG. It is a graph which shows the relationship between the silica content rate of the manifold material in the 1st Embodiment of the fuel cell which concerns on this invention, and the linear expansion coefficient of resin. It is a cross-sectional view of a second embodiment of the fuel cell according to the present invention. FIG. 6 is a developed perspective view showing a fuel inlet manifold in the fuel cell of FIG. 5. FIG. 7 is a cross-sectional view of the fuel inlet manifold of FIG. 6.

  Embodiments of a fuel cell 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 perspective view showing a first embodiment of a fuel cell according to the present invention. 2 is a perspective view showing a stack of the fuel cell of FIG. 1, and FIG. 3 is a cross-sectional view of the fuel cell of FIG.

  The structure of the laminated body of the polymer electrolyte fuel cell stack according to the first embodiment will be described with reference to FIG. The single cell battery 10 includes a membrane / electrode assembly (MEA) 11, an oxidant separator 12 that sandwiches the membrane / electrode assembly 11, and a fuel / cooling water separator 13. An oxidant gas flow passage 14 is provided on the surface of the oxidant separator 12, and an end of the oxidant gas flow path 14 opens on the side surface of the separator. A fuel gas flow passage 15 is provided on the surface of the fuel / cooling water separator 13 on the side in contact with the membrane / electrode assembly 11, and a cooling water flow passage 16 is provided on the other surface. End portions of the fuel gas flow passage 15 and the cooling water flow passage 16 are open to the side surfaces of the separator. A plurality of single cell batteries 10 are stacked to form a stacked body.

  Insulating end plates 17 are arranged on both sides of the laminate. The end plate 17 is made of a heat-resistant resin material such as an epoxy resin, a vinyl ester resin, or a phenol resin, and has a concave recess 19 on the inner side corresponding to the battery reaction portion. A protrusion 20 is provided at a corner of the end plate 17 and is tightened by a tightening stud 21 that passes through a hole provided at the center of the protrusion 20.

  A conductive internal plate (current collector plate) 60 is disposed in the recess 19 of the end plate 17. The conductive inner plate 60 is a flat plate made of a conductive material such as stainless steel. An opening 22 is provided at the center of the recess 19 to take out the generated current of the laminate. A plurality of screw holes 23 for fixing the manifold are provided on the side surface of the end plate 17.

  Next, the configuration of the polymer electrolyte fuel cell according to the first embodiment will be described with reference to FIG. An oxidant inlet / cooling water outlet manifold 30, an oxidant outlet / cooling water inlet manifold 31, a fuel inlet manifold 32, and a fuel outlet manifold 33 are arranged on the side surface of the laminate as external manifolds. A step 34 is provided in a portion of the manifold 30, 31, 32, 33 facing the end plate 17, and the step 34 has a long hole, and the manifold 30, 31, 32, 33 is ended by a bolt 35 through the long hole. It is fixed to the plate 17.

  Next, the configuration of the polymer electrolyte fuel cell stack according to the first embodiment will be described mainly with reference to FIG. As shown in FIG. 2, an oxidant gas flow passage 14 is provided on the surface of the oxidant separator 12, and an end thereof opens to the side surface of the separator. A fuel gas flow passage 15 is provided on one surface of the fuel / cooling water separator 13, and a cooling water flow passage 16 is provided on the other surface, and their end portions open to the side surface of the separator.

  The oxidant inlet / cooling water outlet manifold 30 is divided into an oxidant inlet manifold 30a and a cooling water outlet manifold 30b. Similarly, the oxidant outlet / cooling water inlet manifold 31 is divided into an oxidant outlet manifold 31a and a cooling water inlet manifold 31b.

  The oxidant gas flow passage 14 communicates with the oxidant inlet manifold 30a and the oxidant outlet manifold 31a. The fuel gas flow passage 15 communicates with the fuel inlet manifold 32 and the fuel outlet manifold 33. The coolant flow passage 16 communicates with the coolant inlet manifold 31b and the coolant outlet manifold 30b.

  The oxidant inlet manifold 30a communicates with the oxidant inlet 50, the oxidant outlet manifold 31a communicates with the oxidant outlet 51, the fuel inlet manifold 32 communicates with the fuel inlet 52, and the fuel outlet manifold 33 communicates with the fuel outlet 53. The cooling water inlet manifold 31 b communicates with the cooling water inlet 54, and the cooling water outlet manifold 30 b communicates with the cooling water outlet 55. Thus, the fuel / oxidant gas necessary for the reaction is supplied to and discharged from the membrane electrode assembly, the cooling water at a predetermined flow rate is supplied, and the heat generated by the reaction is cooled.

  Each of the manifolds 30, 31, 32, and 33 must have gas impermeability and electrical insulation, and is preferably manufactured by compression molding or injection molding of a thermoplastic resin or a thermosetting resin with a mold. . Examples of the thermoplastic resin include PPS (polyphenylene sulfide), and examples of the thermosetting resin include an epoxy resin and a phenol resin. The manifold has a box-like shape with the laminated body side as an opening, and the side surface and the inner surface of the manifold are preferably provided with a taper from the laminated body side toward the bottom surface of the manifold to ensure mold releasability. . An insulating sealing material 36 is inserted between the opening of the manifold and the laminate.

  The operating temperature of the polymer electrolyte fuel cell stack is around 80 ° C. On the other hand, the stack is manufactured and assembled at room temperature. For this reason, in an actual operation, there is a possibility of causing a dimensional change due to a difference in thermal expansion of the members of the stack. A separator that constitutes a single cell battery is generally manufactured by molding a compound in which graphite carbon is mixed with a binder resin, using a mold. As the binder resin, for example, a thermoplastic resin such as PPS or a thermosetting resin such as an epoxy resin or a phenol resin is suitable.

A normal separator has a linear expansion coefficient of 1.3 to 1.5 × 10 ⁻⁵ [/ K]. On the other hand, the resin used for the external manifold generally has a large coefficient of linear expansion, which is 2-3 × 10 ⁻⁵ [/ K]. Therefore, in the conventional general configuration, when the stack assembled at room temperature reaches the operating temperature, the inner dimension of the manifold becomes larger than the outer dimension of the separator, resulting in a gap. There is a risk of leaking without being absorbed.

  Therefore, in the present embodiment, a resin having a smaller linear expansion coefficient than the separator is used for the external manifold. Specifically, an inorganic material filler having a small linear expansion coefficient, for example, silica or carbon fiber, is mixed with a thermoplastic resin or a thermosetting resin. As a result, the linear expansion coefficient of the separator can be made smaller. When the material is assembled at room temperature and brought to the operating temperature, the inner dimension of the manifold becomes smaller than the outer dimension of the separator, and pressure is applied by the sealing material 36, thereby eliminating the possibility of leaks.

In FIG. 4, silica (glass beads) having a linear expansion coefficient of 2.0 × 10 ⁻⁶ [/ K] was mixed with a thermosetting resin having a linear expansion coefficient of 2.5 × 10 ⁻⁵ [/ K]. It is a graph which shows the relationship of the linear expansion coefficient of resin obtained by mixing with the silica content rate in the case. As can be seen from FIG. 4, the linear expansion coefficient decreases as the silica content increases, and becomes 1.5 × 10 ⁻⁶ [/ K] or less when the silica content is 43.5% or more. On the other hand, when silica is increased, the fluidity during molding is lowered and the wear of the mold becomes severe, and 87% or more cannot be molded. Therefore, the linear expansion coefficient is preferably 0.5 to 1.5 × 10 ⁻⁵ [/ K].

In the first embodiment, as an example of the separator, the one in which a compound obtained by mixing graphite carbon with a binder resin is molded with a mold has been described. As an example of another material of the separator, a metal separator obtained by press-molding a thin metal plate coil may be used. For example, stainless steel can be used as the metal, and the linear expansion coefficient in that case is 1.5 to 2.0 × 10 ⁻⁵ [/ K]. The linear expansion coefficient is slightly larger than that of the carbon resin molded product, and the resin of the external manifold to be combined is 20% or more of silica and the linear expansion coefficient is 2.0 × 10 ⁻⁵ [/ K] or less, and the linear expansion coefficient is 0.5 to 2 0.0 × 10 ⁻⁵ [/ K] is preferable.

  Here, the seal between the end plate 17 and the separator in the first embodiment will be described.

  As described above, the operating temperature of the polymer electrolyte fuel cell stack is about 80 ° C., whereas the stack is manufactured and assembled at room temperature. For this reason, there is a difference in the dimensional difference between the length in the plane direction of the separator and the length in the direction parallel to the separator of the end plate 17 due to the difference in thermal expansion of the member during actual operation and during manufacture and assembly. .

The separator constituting the unit cell is generally produced by molding a compound in which graphite carbon is mixed with a binder resin with a mold, and the linear expansion coefficient indicating the degree of thermal expansion is 1.3 to 1.5 × 10 ⁻ It is about ⁵ [/ ° C]. On the other hand, when the end plate 17 is made of a phenol resin, the linear expansion coefficient is about 2.5 to 6 × 10 ⁻⁵ [/ ° C.]. Therefore, when the stack assembled at room temperature is in the operating temperature state, the size of the end plate 17 becomes larger than the size of the separator, and the seal of the seal portion between the side surface of the laminate having minute irregularities and the external manifold is sealed. There is a risk that gas or cooling water may leak from the seal portion due to a decrease in surface pressure.

  Therefore, in the present embodiment, a resin having a smaller linear expansion coefficient than the separator is used for the end plate 17. Specifically, it is preferable to mix a thermoplastic resin or a thermosetting resin with a material having a small linear expansion coefficient, for example, silica or carbon fiber. As a result, the linear expansion coefficient of the separator can be made smaller. With this material configuration, when assembled at room temperature and brought to the operating temperature, the dimensions of the end plate become smaller than the dimensions of the separator, and pressure is applied by the seal part between the side of the laminate with minute irregularities and the external manifold. Thus, there is no risk of leaks.

  An example of a preferable specific material of the end plate 17 and its linear expansion coefficient are the same as those of the manifold described above.

  An elastic sealing material (not shown) is inserted into a contact portion between the manifold and the end plate 17. Here, since the laminated body is formed by laminating a large number of individually formed separators, there are minute irregularities on the side surface of the laminated body, and the sealing pressure applied to the sealing material between the manifold and the laminated body is Leakage from the seal portion is likely to occur when it falls. On the other hand, since the side surface of the end plate 17 is formed flat, even when the sealing pressure applied to the sealing material between the manifold and the end plate is reduced when a sealing material having appropriate elasticity is used, the end plate 17 is laminated with the manifold. Leakage is unlikely to occur as compared to the case where the sealing pressure applied to the sealing material between the bodies decreases.

[Second Embodiment]
FIG. 5 is a cross-sectional view of a second embodiment of the fuel cell according to the present invention. 6 is an exploded perspective view showing a fuel inlet manifold in the fuel cell of FIG. FIG. 7 is a cross-sectional view of the fuel inlet manifold of FIG.

  In this embodiment, a composite material of the resin material 41 and the metal plate 40 is used as the material of each manifold 30, 31, 32, 33. That is, as the resin material 41, a thermoplastic resin such as PPS or a thermosetting resin such as an epoxy resin or a phenol resin, which is substantially the same as that of the first embodiment, is used. A metal plate 40 is disposed at a portion where each manifold 30, 31, 32, 33 is in contact with the sealing material 36. As a manufacturing method of the manifold, there is a method in which the metal plate 40 is bonded to the opening of the resin material 41 or the metal plate 40 is arranged in a manifold molding die and the manifold is directly molded on the metal plate 40. is there.

  Other parts are the same as those in the first embodiment.

  The linear expansion coefficient of the metal plate 40 is generally smaller than the linear expansion coefficient of the resin material 41, and the linear expansion coefficient as a composite material of the resin material 41 and the metal plate 40 is made smaller than the linear expansion coefficient of the separator. Similar to the first embodiment, since the linear expansion coefficient of the external manifold is smaller than the linear expansion coefficient of the separator, it is possible to suppress the leakage of gas and cooling water due to the difference in thermal expansion accompanying the temperature rise during operation.

  Furthermore, according to this embodiment, the rigidity of the manifold is increased by using a metal plate, and the thickness of the resin portion of the manifold can be reduced.

[Other Embodiments]
In the first embodiment, the linear expansion coefficient of both the external manifold and the end plate is smaller than the linear expansion coefficient of the separator. However, even if the linear expansion coefficient of only one of the outer manifold and the end plate is smaller than the linear expansion coefficient of the separator, the effect can be partially obtained, so that may be sufficient.

  As a modification of the second embodiment, the resin material 41 may be a mixture of a thermoplastic resin, a thermosetting resin, or the like similar to the first embodiment mixed with silica, carbon fiber, or the like.

  In some cases, a cooling water flow passage and a cooling water manifold may not be provided.

  The embodiment described above is an exemplification, and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the gist of the invention, and are included in the invention described in the scope of claims and the equivalents thereof.

10 Single-cell battery 11 Membrane / electrode assembly (MEA)
12 Oxidant separator 13 Fuel / cooling water separator 14 Oxidant gas flow path 15 Fuel gas flow path 16 Cooling water flow path 17 End plate 19 Depression 20 Protrusion 21 Tightening stud 22 Opening 23 Screw hole 30 Oxidant inlet / cooling water outlet Manifold 30a Oxidant inlet manifold 30b Coolant outlet manifold 31 Oxidant outlet / coolant inlet manifold 31a Oxidant outlet manifold 31b Coolant inlet manifold 32 Fuel inlet manifold 33 Fuel outlet manifold 34 Step 35 Bolt 36 Sealing material 40 Metal plate 41 Resin material 50 Oxidant inlet 51 Oxidant outlet 52 Fuel inlet 53 Fuel outlet 54 Cooling water inlet 55 Cooling water outlet 60 Conductive inner plate (current collector plate)

Claims (10)

A stacked body in which a plurality of single cell batteries are stacked in a predetermined stacking direction, a fuel inlet manifold that distributes fuel gas to each of the plurality of single cell batteries, and an oxidation that distributes oxidant gas to each of the plurality of single cell batteries An agent inlet manifold, a fuel outlet manifold that discharges fuel gas from each of the plurality of single cell cells, and an oxidant outlet manifold that discharges oxidant gas from each of the plurality of single cell cells,
In the fuel cell in which the fuel inlet manifold, the oxidant inlet manifold, the fuel outlet manifold, and the oxidant outlet manifold are arranged so as to extend in the stacking direction in contact with the side surfaces of the stack,
Each of the single cell batteries includes a membrane / electrode composite and a separator that forms a fuel gas flow passage and an oxidant gas flow passage in contact with both surfaces of the membrane / electrode composite across the membrane / electrode composite. And are stacked in the stacking direction,
The fuel gas flow passage is connected to the fuel inlet manifold, the fuel gas flow passage is connected to the fuel outlet manifold, the oxidant gas flow passage is connected to the oxidant inlet manifold, and the oxidant gas flow passage. Is connected to the oxidant outlet manifold,
At least one of the fuel inlet manifold, the fuel outlet manifold, the oxidant inlet manifold, and the oxidant outlet manifold is made of a manifold material having a linear expansion coefficient lower than that of the separator, and the manifold material is an insulating resin. Containing materials,
A fuel cell.   The said manifold material contains the filler of the inorganic material in which a linear expansion coefficient is lower than the said insulating resin in the thermosetting or thermoplastic insulating resin, It is characterized by the above-mentioned. Fuel cell. The manifold material is formed by integrating a metal plate and a resin material,
The fuel cell according to claim 1, wherein the separator and the metal plate are joined via an insulating sealing material.   The fuel cell according to any one of claims 1 to 3, wherein the separator is formed of a molded product of graphite and a binder resin.   The fuel cell according to any one of claims 1 to 3, wherein the separator is formed by press-molding a metal plate. A laminated body in which a plurality of single cell batteries are laminated in a predetermined lamination direction; two end plates that are arranged at both ends of the laminated body in the lamination direction and made of an insulating resin material; and the two sheets Fastening studs that are attached to the end plates and fasten these end plates closer to each other, a fuel inlet manifold that distributes fuel gas to each of the plurality of single cell cells, and an oxidant gas to each of the plurality of single cell cells An oxidant inlet manifold that distributes the fuel, a fuel outlet manifold that discharges fuel gas from each of the plurality of single cell cells, and an oxidant outlet manifold that discharges oxidant gas from each of the plurality of single cell cells,
In the fuel cell in which the fuel inlet manifold, the oxidant inlet manifold, the fuel outlet manifold, and the oxidant outlet manifold are arranged so as to extend in the stacking direction in contact with the side surfaces of the stack,
Each of the single cell batteries includes a membrane / electrode composite and a separator that forms a fuel gas flow passage and an oxidant gas flow passage in contact with both surfaces of the membrane / electrode composite across the membrane / electrode composite. And are stacked in the stacking direction,
The fuel gas flow passage is connected to the fuel inlet manifold, the fuel gas flow passage is connected to the fuel outlet manifold, the oxidant gas flow passage is connected to the oxidant inlet manifold, and the oxidant gas flow passage. Is connected to the oxidant outlet manifold,
The end plate is composed of an end plate material having a linear expansion coefficient lower than that of the separator, and the end plate material contains an insulating resin material;
A fuel cell.   The end plate material contains a filler of an inorganic material having a lower linear expansion coefficient than that of the insulating resin in a thermosetting or thermoplastic insulating resin. The fuel cell as described. The end plate material is formed by integrating a metal plate and a resin material,
The fuel cell according to claim 6, wherein the separator and the metal plate are joined together via an insulating sealing material.   The fuel cell according to any one of claims 6 to 8, wherein the separator is made of a molded product of graphite and a binder resin.   The fuel cell according to any one of claims 6 to 8, wherein the separator is formed by press-molding a metal plate.

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