JP2014107244A - Fuel battery and fuel battery stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for restraining distortion stress generated at a seal member used for a fuel battery.SOLUTION: A fuel battery comprises: a power generation module having a membrane electrode assembly including an electrolyte membrane and an electrode layer, and first and second diffusion layers laminated to sandwich the membrane electrode assembly; first and second separators laminated to sandwich the power generation module; and a seal part arranged on an outer periphery of the power generation module, adhered to the first separator at a first portion of the outer periphery opposed to the first and second separators, adhered to the second separator at a second portion of the outer periphery, and adhered to the electrolyte membrane. The seal part has an inner surface not parallel to a lamination direction except for the outer periphery in a range from an innermost portion to an outermost portion along a plane direction among the first portion and the second portion on at least one of cross sections parallel to the lamination direction and including the power generation module.

Description

  The present invention relates to a fuel cell and a fuel cell stack.

  2. Description of the Related Art There are known fuel cells that directly convert chemical energy of a substance into electrical energy by causing an electrochemical reaction using a reaction gas (fuel gas and oxidant gas). A fuel cell generally includes a membrane electrode gas diffusion layer assembly (hereinafter referred to as “MEA (Membrane Electrode Assembly)”) and a pair of diffusion layers laminated so as to sandwich the MEA. "MEGA (Membrane Electrode & Gas Diffusion Layer Assembly)") and a pair of separators stacked so as to sandwich the MEGA. The MEA has a configuration in which an anode is formed on one surface of an electrolyte membrane and a cathode is formed on the other surface. A seal member is provided on the outer periphery of the MEGA to prevent leakage of reaction gas from the inside of the fuel cell to the outside and mixing of reaction gas between the anode side and the cathode side (referred to as “cross leak”). Is placed.

  In a conventional fuel cell, for example, as described in Patent Document 1, a seal member is integrally formed on the outer periphery of the MEA, and an adhesive layer is formed between both surfaces of the seal member and the separator and between adjacent separators. By forming, variation in the stacking direction in MEGA is suppressed. Further, in Patent Document 2, since a part of a portion where the separator and the seal member face each other is not bonded, followability to deformation that occurs when unit cells of a plurality of fuel cells are stacked and fastened is improved. A fuel cell is disclosed. In Patent Document 3, uncrosslinked solid rubber that is solid at room temperature is crosslinked by heating, and the outer divided body and the inner divided body as a sealing member are integrated to produce a seal member at the time of manufacture. A technique for suppressing the shift is disclosed.

JP 2010-272474 A JP 2010-282940 A JP 2010-244690 A

  However, in the fuel cell disclosed in Patent Document 1, the amount of dimensional change when compressed in the stacking direction is different between the sealing member disposed on the outer periphery and the MEGA disposed on the inner periphery, so that the fuel cell is compressed. When the fastening and the compression are released after being fastened, there is a case where the sealing member is subjected to strain stress and the sealing performance is deteriorated. Moreover, in the technique disclosed in Patent Document 2, the followability to deformation increases when the unit cell is fastened. However, since the area of the bonding surface between the seal member and the separator is reduced, the entire surface is bonded. There is a problem that the sealing performance is deteriorated as compared with the case where it is present. Further, the technique disclosed in Patent Document 3 has a problem that the sealing member is configured by a plurality of divided bodies, which increases the cost of the sealing member and complicates the manufacture of the fuel cell. . Further, there has been a problem that a simple structure is desired to improve the sealing performance by suppressing the strain stress generated in the sealing member when the fuel cell is compressed and when it is not compressed.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a fuel cell is provided. The fuel cell includes a membrane electrode assembly including an electrolyte membrane and electrode layers disposed on both surfaces of the electrolyte membrane, and first and second diffusion layers stacked so as to sandwich the membrane electrode assembly. A power generation module having a layer; first and second separators stacked so as to sandwich the power generation module; and disposed on an outer peripheral portion of the power generation module along a plane direction that is parallel to the surface A first portion of the outer peripheral surface facing the first and second separators is bonded to the first separator and a second portion of the outer peripheral surface is bonded to the second separator; A seal portion bonded to the membrane; and the seal portion includes the power generation module parallel to a stacking direction in which the membrane electrode assembly and the first and second diffusion layers are stacked. Parallel to the stacking direction except for the outer peripheral surface in a range from the innermost portion to the outermost portion along the surface direction among the first portion and the second portion in at least one of the cross sections. Not having an internal surface. According to the fuel cell of this aspect, when the compression is released after the fuel cell is compressed, the fuel cell expands along the stacking direction. In this case, the strain stress generated inside the seal portion due to the internal surface formed on the portion excluding the outer peripheral surface of the seal portion is suppressed by deformation of the vicinity of the internal surface. Therefore, when the compression of the fuel cell is released, even if the amount of dimensional change along the stacking direction in the power generation module and the seal portion is different and a strain stress is generated in the seal portion, the bonded first portion and the first portion Since the portion 2 cannot be peeled off, it is possible to suppress a decrease in the sealing performance of the fuel cell.

(2) In the fuel cell of the above aspect, the seal portion includes a first seal member including the first portion and a second seal member including the second portion; the internal surface May be surfaces on which the first seal member and the second seal member face each other. According to the fuel cell of this embodiment, the inner surface can be easily formed by dividing the seal portion.

(3) In the fuel cell of the above aspect, the thickness along the stacking direction of the portion of the seal portion where the inner surface is located may be the maximum thickness along the stacking direction of the seal portion. Good. According to the fuel cell of this aspect, when the fuel cell is compressed along the stacking direction, the vicinity of the portion where the inner surface is located in the seal portion is deformed before the other portion. After the seal part is deformed, when opposing internal surfaces in the seal part come into contact with each other, the part having the internal surface along the surface direction is thickest along the laminating direction. It can suppress being compressed. Therefore, generation | occurrence | production of the distortion stress in a seal part can be suppressed, and durability of a seal part can be improved.

(4) In the fuel cell of the above aspect, at least one of the first portion and the second portion in the seal portion is bonded to the first or second separator over the entire surface along the surface direction. May be. According to the fuel cell of this aspect, since the area of at least one of the first portion and the second portion is large while forming the inner surface in the seal portion, it is possible to further suppress the deterioration of the seal performance. it can.

  The present invention can be realized in various modes. For example, it is realized in the form of a fuel cell, a fuel cell stack, a seal member used for the fuel cell, a fuel cell power generation module, a fuel cell system, a mobile body including the fuel cell system, a manufacturing method of these devices or systems, Can do.

It is explanatory drawing which shows schematic structure of the fuel cell stack 100 as embodiment of this invention. 4 is an explanatory diagram showing a detailed configuration of a cell module 202. FIG. 5 is an explanatory diagram showing a flow of manufacturing steps of the fuel cell stack 100. FIG. It is explanatory drawing which shows the detailed structure of the produced unit cell 200. FIG. It is explanatory drawing which shows the detailed structure of the cell module 202a in a 1st modification. It is explanatory drawing which shows the detailed structure of the cell module 202b in a 2nd modification. It is explanatory drawing which shows the detailed structure of the cell module 202c in a 3rd modification.

Next, embodiments of the present invention will be described in the following order.
A. Embodiment:
A-1. Fuel cell stack configuration:
A-2. Manufacturing process of fuel cell stack:
B. Variations:

A. Embodiment:
A-1. Fuel cell stack configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell stack 100 as an embodiment of the present invention. The fuel cell stack 100 of this embodiment is a solid polymer fuel cell that is relatively small and has excellent power generation efficiency. As shown in FIG. 1, the fuel cell stack 100 is formed by stacking an end plate 210, a cell stack 201, and an end plate 211 in this order. The fuel cell stack 100 is fastened by fasteners 215 at four corners of the end plate 210 and the end plate 211. The cell stack 201 is formed by stacking a plurality of cell modules 202. The cell module 202 is formed by stacking a plurality of unit cells 200.

  In order to supply the unit cell 200 with hydrogen gas as a fuel gas, compressed air as an oxidant gas (hereinafter also referred to as “reactive gas”) and cooling water, the unit cell 200 is supplied with a unit cell 200. Manifold holes 221, 223, and 225 are formed so as to penetrate the cell stack 201 along the stacking direction in which 200 are stacked. Further, the unreacted gas among the reaction gases supplied from the manifold holes 221, 223, and 225 and the cooling water after circulating through the unit cell 200 are manifolds formed so as to penetrate the cell stack 201. It is discharged out of the fuel cell stack 100 through each of the holes 222, 224 and 226. In each of the unit cells 200 in the fuel cell stack 100, in order to diffuse the reaction gas and the cooling water supplied from the manifold holes 221, 223, 225 along the plane direction perpendicular to the stacking direction, the manifold holes 221, A flow path connected to 223, 225 and manifold holes 222, 224, 226 is formed.

  FIG. 2 is an explanatory diagram showing a detailed configuration of the cell module 202. In FIG. 2, among the part of the cell module 202 in the A1 cross section shown in FIG. 1, the end portion along the surface direction of the MEGA 311 is compressed in the stacking direction and fastened and sealed by the seal member 330. The part is shown. As shown in FIG. 2, the cell module 202 is formed by stacking a plurality of identical unit cells 200 and bonding them together with an adhesive layer 340. FIG. 2 shows a state in which three unit cells 200 are stacked.

  The unit cell 200 is formed by laminating an anode side separator 326, a membrane electrode gas diffusion layer assembly (hereinafter also referred to as “MEGA (Membrane Electrode & Gas Diffusion Layer Assembly)”) 311, and a cathode side separator 324. ing. In the unit cell 200, a seal member 330 is disposed between the anode side separator 326 and the cathode side separator 324. The seal member 330 is disposed on the outer peripheral side of the MEGA 311 along the surface direction. The MEGA 311 corresponds to the power generation module of the present invention.

  The MEGA 311 is formed by laminating an anode side gas diffusion layer 316, a membrane electrode assembly (hereinafter also referred to as “MEA (Membrane Electrode Assembly)”) 311, and a cathode side gas diffusion layer 314. In the MEA 310, a catalyst layer is applied to both surfaces of the electrolyte membrane, an anode is formed on the side facing the anode side gas diffusion layer 316, and a cathode is formed on the side facing the cathode side gas diffusion layer 314. The electrolyte membrane is an ion exchange membrane formed of a fluorine-based resin material or a hydrocarbon-based resin material, and has good proton conductivity in a wet state. The catalyst layer is a layer that provides a catalyst that promotes an electrode reaction, and is formed of a material that includes a catalyst metal-supported carrier and an ionomer as an electrolyte.

  The anode side gas diffusion layer 316 is partially bonded to the anode side separator 326 along the surface direction. The anode-side gas diffusion layer 316 is formed to have a smaller area along the surface direction than the MEA 310 and the cathode-side gas diffusion layer 314. The anode-side separator 326 and the cathode-side separator 324 have a flat plate shape with irregularities formed in the stacking direction. Between the anode gas diffusion layer 316 and the anode separator 326, a plurality of hydrogen gas flow paths fp1 connected to the manifold hole 221 and the manifold hole 222 are formed. A plurality of hydrogen gas flow paths fp1 and a plurality of oxidant gas flow paths fp2 described later are formed in the unit cell 200 along the surface direction. The hydrogen gas flow path fp <b> 1 diffuses hydrogen gas supplied through the manifold hole 221 along the surface direction, and discharges unreacted hydrogen gas through the manifold hole 222.

  The cathode side gas diffusion layer 314 is partially bonded to the cathode side separator 324 along the surface direction. Between the cathode gas diffusion layer 314 and the cathode separator 324, a manifold hole 223 and a plurality of oxidant gas flow paths fp2 connected to the manifold hole 224 are formed. The oxidant gas flow path fp <b> 2 diffuses the oxidant gas supplied through the manifold hole 223 along the surface direction and discharges the unreacted oxidant gas through the manifold hole 224. The anode side gas diffusion layer 316 and the cathode side gas diffusion layer 314 are formed of a diffusion layer base material in which a plurality of carbon fibers such as carbon cloth and carbon paper are hardened with a resin. The anode-side separator 326 and the cathode-side separator 324 are formed of a dense material that does not transmit gas and also has conductivity, such as densely compressed carbon, metal, and conductive resin.

  The outer peripheral portion along the surface direction of the MEGA 311 is sealed by the seal member 330 so that the reaction gas does not leak outside the unit cell 200. The seal member 330 is configured to be divided into a first seal portion 336 and a second seal portion 334. The first seal portion 336 and the second seal portion 334 are bonded to each other on an adhesive surface 331 that is a part of a surface facing each other along the stacking direction. The first seal portion 336 is formed so as to protrude from the inner peripheral portion of the unit cell 200 along the surface direction as compared with the second seal portion 334. The first seal portion 336 is bonded to the MEA 310 at a surface 332 facing the MEA 310 along the stacking direction. By adhering first seal part 336 and MEA 310, mixing of hydrogen gas and oxidant gas (referred to as “cross leak”) in unit cell 200 is prevented. Further, the first seal portion 336 is bonded to the anode side separator 326 on the bonding surface 337. The first seal portion 336 and the anode-side separator 326 are bonded to the inner peripheral surface L1 that is the innermost side along the surface direction on the bonding surface 337. Although not shown, the bonding surface 337 extends to the outer peripheral ends of the first seal portion 336 and the anode separator 326 along the surface direction. The thickness along the stacking direction of the first seal portion 336 in the fastened state is the thickness T1, which is the same thickness along the surface direction.

  The second seal portion 334 is not in contact with the MEGA 311 and is bonded to the cathode separator 324 at the bonding surface 335. The adhesive surface 337 and the adhesive surface 335 are formed at positions facing each other via the first seal portion 336 and the second seal portion 334 along the stacking direction. The second seal portion 334 and the cathode-side separator 324 are bonded to the inner peripheral surface L1 that is the innermost side along the surface direction on the bonding surface 335 in the same manner as the bonding surface 337. Further, the adhesive surface 335 extends to the end portions of the second seal portion 334 and the cathode side separator 324 along the surface direction. The thickness along the stacking direction of the second seal portion 334 is the thickness T2, which is the same thickness along the surface direction. Note that each of the adhesive surface 337 and the adhesive surface 335 corresponds to a first portion and a second portion in the present invention. The adhesive surface 331, the adhesive surface 337, and the adhesive surface 335 are displayed with emphasis by bold lines in FIG. 2, but omitted and emphasized display is omitted in FIG.

  The first seal portion 336 has an inner surface 338 that faces the second seal portion 334. Similarly, the second seal portion 334 has an inner surface 333 that faces the inner surface 338 of the first seal portion 336. As shown in FIG. 2, the inner surface 338 and the inner surface 333 are in close contact with each other when the unit cell 200 is compressed and fastened along the stacking direction. The inner surface 338 and the inner surface 333 are surfaces that are not parallel to the stacking direction in the portion excluding the outer peripheral portion of the seal member 330 facing the anode side separator 326 or the cathode side separator 324. Further, the inner surface 338 and the inner surface 333 are formed on the outer peripheral side along the surface direction of the unit cell 200 rather than the inner peripheral surface L1 parallel to the stacking direction.

A-2. Manufacturing process of fuel cell stack:
FIG. 3 is an explanatory diagram showing the flow of the manufacturing process of the fuel cell stack 100. As shown in FIG. 3, in the manufacture of the fuel cell stack 100, the unit cell 200 is first manufactured (step S410). In the unit cell 200, the MEGA 311 is manufactured by laminating and bonding the anode side gas diffusion layer 316 and the cathode side gas diffusion layer 314 to the MEA 310. The unit cell 200 is formed by laminating an anode side separator 326 and a cathode side separator 324 so as to sandwich the MEGA 311 and the seal member 330. Next, the produced plurality of unit cells 200 are stacked (step S420). Each unit cell 200 is bonded and stacked in the stacking direction by an adhesive layer 340.

  FIG. 4 is an explanatory diagram showing a detailed configuration of the manufactured unit cell 200. FIG. 4 shows three unit cells 200 among the plurality of unit cells 200 bonded and stacked in the stacking direction by the adhesive layer 340. In FIG. 4, the stacked unit cells 200 are not compressed in the stacking direction. As shown in FIG. 4, the thickness of the first seal portion 336 along the stacking direction is a thickness T1 ', which is the same thickness along the surface direction. Further, the thickness along the stacking direction in the second seal portion 334 is the thickness T2 ', which is the same thickness along the surface direction. The thickness (T1 ′ + T2 ′) along the stacking direction of the portion where the inner surface 338 and the inner surface 333 are located in the seal member 330 is the maximum thickness along the stacking direction of the seal member 330. The first seal portion 336 and the second seal portion 334 have a shape in which a step is provided along the stacking direction. Thereby, a space SP is formed between the inner surface 338 and the inner surface 333. The thickness along the stacking direction of the space SP in the portion where the bonding surface 337 and the bonding surface 335 are located is the thickness Tsp ′.

  After the plurality of unit cells 200 are stacked, when sandwiched between the end plates 210 and 211 and compressed in the stacking direction, the cell stack 201 is manufactured (step S430 in FIG. 3). When the unit cell 200 is compressed in the stacking direction, the thickness along the stacking direction of the seal member 330 and the MEGA 311 decreases as shown in FIG. Further, the seal member 330 is elastically deformed so that the thickness Tsp along the stacking direction of the space SP becomes small, and the inner surface 338 and the inner surface 333 are in close contact with each other. Thereafter, the unit cell 200 is further compressed in the stacking direction, and the thicknesses along the surface direction of the first seal portion 336 and the second seal portion 334 are determined from the thickness T1 ′ and the thickness T2 ′, respectively. It becomes small to thickness T1 and thickness T2.

  As described above, in the unit cell 200 according to the present embodiment, the unit cell 200 is formed by stacking the anode side separator 326, the MEGA 311 and the cathode side separator 324. The MEGA 311 is formed by stacking an anode side gas diffusion layer 316, an MEA 310, and a cathode side gas diffusion layer 314. The MEA 310 is formed by applying a catalyst layer on both surfaces of an electrolyte membrane. Further, the seal member 330 is bonded to the anode side separator 326 on the bonding surface 337, and is bonded to the cathode side separator 324 on the bonding surface 335. An inner surface 338 and an inner surface 333 that are not parallel to the stacking direction are formed in the seal member 330 in a range from the adhesive surface 337 and the adhesive surface 335 to the innermost inner peripheral surface L1 along the surface direction. ing. Therefore, in the unit cell 200 of this embodiment, when the compression and fastening are released after the fuel cell stack 100 is compressed and fastened, the compressed state of the MEGA 311 is released and the unit cell 200 expands in the stacking direction. . In this case, since the internal surface 338 and the internal surface 333 are formed inside the seal member 330, the strain stress generated inside the seal member 330 is elastic in the vicinity of the internal surface 338 and the internal surface 333. Suppressed by deformation. Therefore, when the MEGA 311 is released from the compressed state, even if the MEGA 311 and the seal member 330 have different dimensional changes along the stacking direction and a strain stress is generated in the seal member 330, the adhesive surface 337 and the adhesive surface 335 Since it does not peel off, it can suppress that the sealing performance of the unit cell 200 falls.

  In the unit cell 200 according to the present embodiment, the seal member 330 includes a first seal portion 336 and a second seal portion 334. An inner surface 338 and an inner surface 333 are formed on the surfaces where the first seal portion 336 and the second seal portion 334 face each other. Therefore, in the unit cell 200, the internal surface 338 and the internal surface 333 can be easily formed by dividing the seal member 330.

  In the unit cell 200 in the present embodiment, the thickness (T1 ′ + T2 ′) along the stacking direction of the portion where the inner surface 338 and the first seal portion 336 are located in the seal member 330 is the stacking direction in the seal member 330. Is the maximum thickness along. Therefore, when the unit cell 200 is compressed along the stacking direction, the vicinity of the portion where the inner surface 338 and the inner surface 333 are located in the seal member 330 is elastically deformed before the other portions. After the seal member 330 is elastically deformed, when the inner surface 338 and the inner surface 333 come into contact with each other, the portion having the inner surface 338 and the inner surface 333 along the surface direction is thickest along the stacking direction. Therefore, it can suppress that other parts are compressed too much. Therefore, the generation of strain stress in the seal member 330 can be suppressed, and the durability of the seal member 330 can be improved.

B. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

B1. Modification 1:
FIG. 5 is an explanatory diagram showing a detailed configuration of the cell module 202a in the first modification. In the first modification, the first seal portion 336a in the seal member 330 of the embodiment is different from the first seal portion 336 of the embodiment, and other configurations are the same as those of the embodiment. FIG. 5 shows a state where the unit cell 200a is not compressed in the stacking direction. As shown in FIG. 5, the seal member 330a is bonded to the anode side separator 326 on the bonding surface 337a. The first seal portion 336a is bonded by an adhesive surface 337a that is the entire surface facing the anode side separator 326. The first seal portion 336a and the anode separator 326 are bonded to the inner peripheral surface L1a which is the innermost side along the surface direction on the bonding surface 337a. Further, the second seal portion 334 and the cathode side separator 324 are bonded to the inner peripheral surface L2a that is the innermost side along the surface direction on the bonding surface 335. The inner peripheral surface L2a is the same inner peripheral surface as the inner peripheral surface L1 in the embodiment.

  In the unit cell 200a in the first modified example, one of the first seal portion 336a and the second seal portion 334 has an adhesive surface 337a that is the entire surface along the surface direction, and the anode The side separator 326 is bonded. Therefore, in this unit cell 200a, since the area of the adhesion surface 337a is large while forming the inner surface 338a and the inner surface 333 on the seal member 330a, it is possible to further suppress the deterioration of the sealing performance.

B2. Modification 2:
FIG. 6 is an explanatory diagram showing a detailed configuration of the cell module 202b in the second modification. In the second modification, the seal member 330b is different from the seal member 330 of the embodiment, and other configurations are the same as those of the embodiment. As shown in FIG. 6, in the seal member 330b, the shape of the first seal portion 336b and the shape of the second seal portion 334b are different from those in the first embodiment. Specifically, the position of the bonding surface 337b bonded to the anode side separator 326 is different from the position of the bonding surface 335b bonded to the cathode side separator 324. Further, the position of the inner surface 338b formed on the first seal portion 336b is different from the position of the inner surface 333b formed on the second seal portion 334b. Further, the first seal portion 336b has different heat in the stacking direction depending on the position of the first seal portion 336b.

  The first seal portion 336b and the anode-side separator 326 are bonded to the inner peripheral surface L1b that is the innermost side along the surface direction on the bonding surface 337b. In addition, the second seal portion 334b and the cathode-side separator 324 are bonded to the innermost inner peripheral surface L2b along the surface direction on the bonding surface 335b. The inner surface 338b and the inner surface 333b are formed on the outer peripheral side with respect to the inner peripheral surface L1b along the surface direction. The first seal portion 336b has the largest thickness along the stacking direction passing through the inner surface 338b, and has a thickness T1b '. The second seal portion 334b has the largest thickness along the stacking direction passing through the inner surface 333b, and has a thickness T2b '. Therefore, the maximum value of the thickness along the stacking direction in the seal member 330b is the thickness (T1b ′ + T2b ′), and it is along the stacking direction of the portion of the seal member 330b where the inner surface 338b and the inner surface 333b are located. Thickness. Therefore, in the unit cell 200b in the second modification, it is possible to suppress the generation of strain stress in the seal member 330b and to suppress the deterioration of the sealing performance.

B3. Modification 3:
FIG. 7 is an explanatory diagram showing a detailed configuration of the cell module 202c in the third modification. In the third modification, the seal member 330c is different from the seal member 330 of the embodiment, and other configurations are the same as those of the embodiment. FIG. 5A shows the cell module 202c in a state before being fastened, and FIG. 5B shows the cell module 202c after being fastened.

  As shown in FIG. 7A, unlike the first embodiment, the seal member 330c is integrally formed without being divided into two seal portions. In the seal member 330c, an internal surface 338c, an internal surface 333c, and a space SPc formed by the internal surface 338c and the internal surface 333c are formed. The seal member 330c is bonded to the anode side separator 326 at the bonding surface 337c, and is bonded to the cathode side separator 324 at the bonding surface 335c. The adhesive surface 337c and the adhesive surface 335c are formed at positions facing each other with the seal member 330c interposed therebetween. The sealing member 330c is bonded to the inner peripheral surface L1c that is the innermost side along the surface direction at the bonding surface 337c and the bonding surface 335c. The inner surface 338c and the inner surface 333c are formed on the outer peripheral side with respect to the inner peripheral surface L1c along the surface direction.

  In the third modification, the thickness along the stacking direction of the portion where the inner surface 333c and the inner surface 333c are located in the seal member 330c is the thickness (T1c ′ + T2c ′), and the other portion in the seal member 330c. It is thinner than. Therefore, as shown in FIG. 7B, the thickness (T1c + T2c) after the seal member 330c is compressed in the stacking direction is thinner than other portions, and the inner surface 338c and the inner surface 333c are not in close contact with each other. The fuel cell stack 100c is fastened with the space SPc remaining as a space. As described above, the thickness (T1c ′ + T2c ′) along the stacking direction of the portion of the seal member 330c where the inner surface 338c and the inner surface 333c are located is not the maximum thickness, and the unit cell 200c is compressed. Even if the space SPc remains in the state of being damaged, the generation of strain stress in the seal member 330c can be suppressed. Moreover, in the unit cell 200c, since the sealing member 330c is formed as one component, the production of the unit cell 200c can be simplified.

B4. Modification 4:
In the above embodiment, the anode side gas diffusion layer 316 has a smaller area than the cathode side gas diffusion layer 314 along the surface direction. However, the anode side gas diffusion layer 316 and the cathode side gas diffusion layer 314 have the same area. The magnitude relationship with is not limited to this and can be variously modified. For example, the cathode side gas diffusion layer 314 may have an area smaller than the anode side gas diffusion layer 316 along the stacking direction, or the cathode side gas diffusion layer 314 and the anode side gas diffusion layer 316 may have the same area. May be.

  In the above embodiment, the seal member 330 and the MEA 310 are bonded to each other at the surface 332. However, the mode for preventing cross leak of the reaction gas is not limited to this, and various modifications can be made. For example, the MEA 310 and the seal member 330 are not opposed to each other along the stacking direction, and the anode-side gas diffusion layer 316 or the cathode-side gas diffusion layer 314 is impregnated with the seal member 330, thereby preventing cross leak of the reaction gas. May be. Alternatively, the anode side gas diffusion layer 316 and the MEA 310 may be bonded not in the plane direction but in the stacking direction, so that the seal member 330 and the MEGA 311 may be bonded to prevent cross leakage of the reaction gas.

  In the above embodiment, the bonding surface 337 and the bonding surface 335 between the sealing member 330 and the anode side gas diffusion layer 316 and the cathode side gas diffusion layer 314 are formed at positions facing each other with the sealing member 330 interposed therebetween. The position where the bonding surface 335 is formed is not limited to this, and various modifications are possible. For example, the adhesive surface 337 is formed at two locations separated along the surface direction, the adhesive surface 335 is formed between the two adhesive surfaces 337 along the surface direction, and the adhesive surface 335 on the seal member 330 is positioned. In the cross section along the stacking direction, the inner surface 338 and the adhesive surface 335 may be formed. In other words, the figure connecting the two bonding surfaces 337 and the bonding surface 335 forms a triangular positional relationship in the cross section along the stacking direction, and the inner surface 338 and the bonding surface 335 are inside the triangle. And are formed.

  In the above embodiment, each of the unit cells 200 constituting the cell module 202 forms the inner surface 338 and the inner surface 333. However, not all unit cells 200 constituting the cell module 202 necessarily include the inner surface 338 and the inner surface 333. There is no need to have a surface 333. Various types of unit cells 200 constituting the cell module 202 can be modified. For example, in the cell module 202, the unit cell 200 including the sealing member 330 having the inner surface 338 and the inner surface 333 and the unit cell 200 including the sealing member not having the inner surface 338 and the inner surface 333 are alternately arranged. It may be laminated. In addition, the inner surface 338 and the inner surface 333 may not be formed in all cross sections along all the stacking directions in which the MEGA 311 is included in the unit cell 200.

  In the above embodiment, the inner surface 338 and the inner surface 333 formed on the seal member 330 are surfaces that divide the seal member 330 along the stacking direction, but are not parallel to the stacking direction of the seal member 330. Is not limited to this embodiment, and can be variously modified. For example, the inner surface formed in the seal member 330 may be a cut or notch formed in the seal member 330. Further, the shape of the inner surface is not limited to a flat surface, and may be a shape such as a circular space.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each form described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 100 ... Fuel cell stack 200 ... Unit cell 201 ... Cell stack 202 ... Cell module 210, 211 ... End plate 215 ... Fasteners 221, 222, 223, 224, 225, 226 ... Manifold hole 310 ... MEA
311 ... MEGA
314... Cathode side gas diffusion layer 316... Anode side gas diffusion layer 324... Cathode side separator 326... Anode side separator 330. 336: First seal portion 337: Adhesion surface 338 ... Internal surface 340 ... Adhesive layer L1 ... Inner peripheral surface of adhesive surface 337 L2 ... Inner peripheral surface of adhesive surface 335 T1, T1 '... Thickness of first seal portion 336 Tsp ... thickness of space SP T2, T2 '... thickness SP ... space fp1 ... hydrogen gas flow path fp2 ... oxidant gas flow path

Claims (5)

A fuel cell,
A membrane electrode assembly including an electrolyte membrane and electrode layers disposed on both surfaces of the electrolyte membrane; and first and second diffusion layers stacked so as to sandwich the membrane electrode assembly. A power generation module;
First and second separators stacked so as to sandwich the power generation module;
It is arrange | positioned at the outer peripheral part of the said electric power generation module along the surface direction which is a direction parallel to the said surface, and is adhere | attached on the said 1st separator in the 1st part in the outer peripheral surface facing the said 1st and 2nd separator. And a seal portion bonded to the second separator at the second portion of the outer peripheral surface and bonded to the electrolyte membrane,
The seal portion includes the first portion and the second portion in at least one of cross sections including the power generation module parallel to a stacking direction in which the membrane electrode assembly and the first and second diffusion layers are stacked. And an inner surface that is not parallel to the stacking direction except for the outer peripheral surface in a range from the innermost part to the outermost part along the surface direction. The fuel cell according to claim 1,
The seal portion includes a first seal member including the first portion, and a second seal member including the second portion,
The fuel cell, wherein the inner surface is a surface where the first seal member and the second seal member face each other. The fuel cell according to claim 1 or 2, wherein
The fuel cell in which the thickness along the stacking direction of the portion of the seal portion where the inner surface is located is the maximum thickness along the stacking direction of the seal portion. A fuel cell according to any one of claims 1 to 3, wherein
At least one of the first portion and the second portion in the seal portion is bonded to the first or second separator over the entire surface along the surface direction. A fuel cell stack in which a plurality of fuel cells are stacked,
Each of the plurality of fuel cells is a fuel cell stack, which is the fuel cell according to any one of claims 1 to 4.

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