Fuel battery, method for manufacturing the same, and formation body for fuel cell used in manufacture of the same

Abstract

To provide a fuel cell which can independently regulate thickness of an anode side gas diffusion layer and thickness of a cathode side gas diffusion layer.SOLUTION: A fuel cell 1 includes a first separator 10a arranged on the side of an anode side gas diffusion layer 7 and a second separator 10b arranged on the side of a cathode gas side diffusion layer 8. An end 3a of an electrolyte membrane 3 projects to the outside from end faces of electrodes 4 and 5. A seal part 11 has a first base material 14a arranged along the end face of the anode side gas diffusion layer 7 between one surface of the end 3a of the electrolyte membrane 3 and the first separator 10a, and a second base material 14b arranged along the end face of the cathode side gas diffusion layer 8 between the other surface of the end 3a of the electrolyte membrane 3 and the second separator 10b. A part of a thermoplastic resin 12 is formed at least on the one surface and the other surface of the first base material 14a, and the one surface and the other surface of the second base material 14b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fuel cell, a method for manufacturing the fuel cell, and a fuel cell forming body used in manufacturing the fuel cell. [Background technology]

[0002] The fuel cell described in Patent Document 1 includes a membrane electrode assembly (MEA), which is a power generating body in which electrodes (catalytic electrodes) carrying a catalyst for promoting the fuel cell reaction are arranged on both sides of an electrolyte membrane. An anode-side gas diffusion layer is arranged on one side of the MEA to diffuse a reactant gas (e.g., hydrogen) across the entire catalytic electrode, and a cathode-side gas diffusion layer is arranged on the other side of the MEA to diffuse a reactant gas (e.g., oxygen) across the entire catalytic electrode. The membrane electrode gas diffusion layer assembly (MEGA), in which the anode-side gas diffusion layer and the cathode-side gas diffusion layer are arranged, is sandwiched between a pair of separators. The pair of separators is electrically insulated by a sealing member provided on the outside of the MEGA. The sealing member includes a core layer made of resin and a pair of skin layers made of thermoplastic resin, which are formed on both surface layers of the core layer that contact the pair of separators and bond the pair of separators to the core layer.

[0003] According to the fuel cell described in Patent Document 1, the thickness of the skin layer of the sealing material can change to absorb changes in the thickness of the MEGA, which changes in response to the load applied through a pair of separators, making it possible to easily form a fuel cell with a constant gap between a pair of separators as an integrated unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-120248 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, it has become clear that the thickness of the anode-side gas diffusion layer and the thickness of the cathode-side gas diffusion layer affect the power generation performance of a fuel cell. In the fuel cell described in Patent Document 1, although the gap between the pair of separators can be specified to be constant, it is not possible to specify the thickness of the anode-side gas diffusion layer and the thickness of the cathode-side gas diffusion layer independently.

[0006] Therefore, an object of the present invention is to provide a fuel cell in which the thickness of the anode-side gas diffusion layer and the thickness of the cathode-side gas diffusion layer can be independently specified, a method for manufacturing such a fuel cell, and a fuel cell forming body used in manufacturing such a fuel cell. [Means for solving the problem]

[0007] One aspect of the present invention is a fuel cell comprising: an electrolyte membrane; a membrane electrode assembly having electrodes disposed on one side and the other side of the electrolyte membrane; an anode-side gas diffusion layer disposed on one side of the membrane electrode assembly; a cathode-side gas diffusion layer disposed on the other side of the membrane electrode assembly; seals containing a thermoplastic resin disposed on end faces of the anode-side gas diffusion layer and the cathode-side gas diffusion layer; and a first separator and a second separator sandwiching the membrane electrode assembly having the anode-side gas diffusion layer and the cathode-side gas diffusion layer and the seals, the first separator and the second separator being disposed on the anode-side gas diffusion layer side. and a second separator disposed on the side of the cathode-side gas diffusion layer, wherein an end of the electrolyte membrane protrudes outward beyond the end face of the electrode, and the sealing portion includes a first substrate disposed along the end face of the anode-side gas diffusion layer between one side of the end of the electrolyte membrane and the first separator, and a second substrate disposed along the end face of the cathode-side gas diffusion layer between the other side of the end of the electrolyte membrane and the second separator, and a portion of the thermoplastic resin is formed on at least one side and the other side of the first substrate and one side and the other side of the second substrate. Another aspect of the present invention is a fuel cell manufacturing method for manufacturing the fuel cell described in the one aspect of the present invention. Another aspect of the present invention is a fuel cell formed body used in the fuel cell manufacturing method for manufacturing the fuel cell described in the other aspect of the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a fuel cell in which the thickness of the anode-side gas diffusion layer and the thickness of the cathode-side gas diffusion layer can be independently specified, a method for manufacturing such a fuel cell, and a fuel cell forming body used in manufacturing such a fuel cell. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an exploded perspective view schematically illustrating the configuration of a fuel cell according to a first embodiment. [Figure 2] FIG. 1 is an explanatory diagram schematically showing a cross-sectional configuration of a fuel cell according to a first embodiment. [Figure 3A]FIG. 2 is an explanatory diagram conceptually showing the method for manufacturing the fuel cell according to the first embodiment, showing the cross-sectional structure of the fuel cell before pressing. [Figure 3B] FIG. 2 is an explanatory diagram conceptually showing the method for manufacturing the fuel cell according to the first embodiment, illustrating the cross-sectional structure of the fuel cell after pressing. [Figure 4] 1 is an explanatory diagram schematically showing a cross-sectional configuration of a fuel cell forming body used in a method for manufacturing a fuel cell according to a first embodiment. FIG. [Figure 5A] FIG. 3 is an explanatory view schematically showing the initial stage in which a load is applied to a fuel cell forming body used in the method for manufacturing a fuel cell according to the first embodiment. [Figure 5B] FIG. 4 is an explanatory view schematically showing a second stage in which a load is applied to the fuel cell forming body used in the method for manufacturing a fuel cell according to the first embodiment. [Figure 5C] FIG. 4 is an explanatory view schematically showing the final stage of applying a load to the fuel cell forming body used in the method for manufacturing a fuel cell according to the first embodiment. [Figure 6] 5 is an explanatory view schematically showing a cross-sectional configuration of another form of a fuel cell forming body used in the method for manufacturing a fuel cell according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The fuel cell 1 according to this embodiment will be described below with reference to the accompanying drawings. In addition, unless otherwise specified, in Figures 1 to 5, the direction in which the components of the fuel cell 1 are stacked, i.e., the vertical direction in Figures 1 to 5, will be referred to as the "stacking direction" of the fuel cell 1. In addition, the surface where the components of the fuel cell 1 are stacked and adjacent to each other will be referred to as the stacking surface.

[0011] A fuel cell 1 according to an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is an exploded perspective view showing a schematic configuration of a fuel cell. The fuel cell 1 usually has a stack structure in which a plurality of fuel cell units 2 are stacked. Note that in FIGS. 1 to 5, only a single fuel cell unit 2 included in the fuel cell 1 is shown, and the other fuel cell units 2 are not shown. In this specification, a single fuel cell unit 2 will be described as the fuel cell 1.

[0012] The fuel cell 1 is a device that generates electricity using, for example, air as an oxidizing gas, which is a reactive gas, and hydrogen as a fuel gas, which is also a reactive gas, and the fuel cell 1 of this embodiment is a solid polymer fuel cell.

[0013] The fuel cell 1 comprises an electrolyte membrane 3, a membrane electrode assembly (MEA) 6 which is a power generating body having an anode-side catalytic electrode 4 arranged on one side (stacking surface: upper side in FIG. 1) of the electrolyte membrane 3 and a cathode-side catalytic electrode 5 (not shown in FIG. 1) arranged on the other side (stacking surface: lower side in FIG. 1) of the electrolyte membrane 3, a membrane electrode gas diffusion layer assembly (MEGA) 9 having an anode-side gas diffusion layer 7 arranged on one side (stacking surface: upper side in FIG. 1) of the MEA 6 and a cathode-side gas diffusion layer 8 arranged on the other side (stacking surface: lower side in FIG. 1) of the MEA 6, and a pair of separators 10 which sandwich the MEGA 9.

[0014] The anode catalytic electrode 4 and the cathode catalytic electrode 5 are electrodes that support a catalyst for promoting the fuel cell reaction, and both the anode catalytic electrode 4 and the cathode catalytic electrode 5 are arranged in the center, excluding the end face sides, of the electrolyte membrane 3. In other words, the end face side, or end 3a, of the electrolyte membrane 3 (hereinafter referred to as the end 3a of the electrolyte membrane 3) protrudes outward beyond the end face of the anode catalytic electrode 4 and the end face of the cathode catalytic electrode 5. Therefore, the anode gas diffusion layer 7 and the cathode gas diffusion layer 8 are not arranged at the end 3a of the electrolyte membrane 3.

[0015] The anode-side gas diffusion layer 7 diffuses a reactant gas (e.g., hydrogen) to distribute it throughout the anode-side catalytic electrode 4. The cathode-side gas diffusion layer 8 diffuses a reactant gas (e.g., oxygen) to distribute it throughout the cathode-side catalytic electrode 5. The pair of separators 10 is composed of a first separator 10a arranged on the anode-side gas diffusion layer 7 side and a second separator 10b arranged on the cathode-side gas diffusion layer 8 side. That is, the first separator 10a is arranged on the surface of the anode-side gas diffusion layer 7 opposite to the side facing the MEA 6, which is arranged on one side of the MEA 6. The second separator 10b is arranged on the surface of the cathode-side gas diffusion layer 8 opposite to the side facing the MEA 6, which is arranged on the other side of the MEA 6. The first separator 10a supplies a reactant gas (e.g., hydrogen) to the anode-side gas diffusion layer 7. The second separator 10b supplies a reactant gas (for example, oxygen) to the cathode gas diffusion layer 8.

[0016] Next, the cross-sectional structure of the fuel cell 1 will be described with reference to FIG. 2. FIG. 2 is an explanatory diagram that schematically illustrates the cross-sectional structure of the fuel cell 1. As described above, the fuel cell 1 includes an MEA 6 in which an anode catalyst electrode 4 is disposed on one side of an electrolyte membrane 3 and a cathode catalyst electrode 5 is disposed on the other side of the electrolyte membrane 3; an MEGA 9 in which an anode gas diffusion layer 7 is disposed on one side of the MEA 6 and a cathode gas diffusion layer 8 is disposed on the other side of the MEA 6; and a pair of separators 10 that sandwich the MEGA 9. A first flow path 21a is formed on the surface of the first separator 10a facing the anode gas diffusion layer 7 for supplying a reactant gas (e.g., hydrogen) to the adjacent anode gas diffusion layer 7. A second flow path 21b is formed on the surface of the second separator 10b facing the cathode gas diffusion layer 8 for supplying a reactant gas (e.g., oxygen) to the adjacent cathode gas diffusion layer 8.

[0017] Between a pair of separators 10 consisting of a first separator 10a and a second separator 10b, and on the outer sides of the end faces of the anode-side gas diffusion layer 7 and the cathode-side gas diffusion layer 8, a seal portion 11 is disposed along the end faces of the anode-side gas diffusion layer 7 and the cathode-side gas diffusion layer 8. The seal portion 11 contains a thermoplastic resin 12. The seal portion 11 bulges outward beyond the end 13a of the first separator 10a and the end 13b of the second separator, and is formed so as to cover the end faces including the end face of the electrolyte membrane 3. Specifically, a portion of the thermoplastic resin 12 contained in the seal portion 11 bulges outward beyond the end 13a of the first separator 10a and the end 13b of the second separator, and is formed so as to cover the end face of the electrolyte membrane 3, a portion of one side of the end 3a of the electrolyte membrane 3, and a portion of the other side of the end 3a of the electrolyte membrane 3. A portion of the thermoplastic resin 12 of the seal portion 11 bulges outward beyond the end 13a of the first separator 10a and the end 13b of the second separator 10a, and is formed to cover the end face of the electrolyte membrane 3, a portion of one side of the end 3a of the electrolyte membrane 3, and a portion of the other side of the end 3a of the electrolyte membrane 3, thereby electrically insulating the pair of separators 10 from each other. In this specification, the term "end face" refers to a face perpendicular to the stacking surface of each member and in the thickness direction of each member. The term "outside" refers to the side of the end face of each member (the left side in Figures 2 to 5), and the term "inside" refers to the side opposite the "outside" and toward the center of each member (the right side in Figures 2 to 5).

[0018] The seal portion 11 has a first substrate 14a made of resin and disposed along the end face of the anode-side gas diffusion layer 7 between one surface (the upper surface in FIG. 2 ) of the end portion 3a of the electrolyte membrane 3 and the first separator 10a, and portions of thermoplastic resin 12 are formed on one and the other surfaces of the first substrate 14a. That is, the seal portion 11 includes a first seal portion 11a formed in a three-layer structure including the first substrate 14a and portions of thermoplastic resin 12 formed on both surfaces of the first substrate 14a. Here, the thermoplastic resin 12 formed on one surface of the first substrate 14a in the first seal portion 11a is the thermoplastic resin 12 disposed between the first substrate 14a and the first separator 10a. The seal portion 11 has a second substrate 14b made of resin and disposed along the end face of the cathode-side gas diffusion layer 8 between the other surface (the lower surface in FIG. 2 ) of the end 3a of the electrolyte membrane 3 and the second separator 10b, and portions of thermoplastic resin 12 are formed on one and the other surfaces of the second substrate 14b. That is, the seal portion 11 includes a second seal portion 11b formed in a three-layer structure including the second substrate 14b and portions of the thermoplastic resin 12 formed on both surfaces of the second substrate 14b. Here, the thermoplastic resin 12 formed on the other surface of the second substrate 14b in the second seal portion 11b is the thermoplastic resin 12 disposed between the second substrate 14b and the second separator 10b.

[0019] The thickness of the first substrate 14a is set in accordance with the thickness of the anode side gas diffusion layer 7, and the thickness of the second substrate 14b is set in accordance with the thickness of the cathode side gas diffusion layer 8.

[0020] The fuel cell manufacturing method for manufacturing the fuel cell 1 will be described in detail later, but the fuel cell manufacturing method for manufacturing the fuel cell 1 involves applying a load to the first seal portion 11a and the anode side gas diffusion layer 7, and the second seal portion 11b and the cathode side gas diffusion layer 8, via a pair of separators 10 consisting of a first separator 10a and a second separator 10b, at a predetermined temperature, thereby bonding the first separator 10a to a portion of the thermoplastic resin 12 formed on one side of the first substrate 14a in the first seal portion 11a, and bonding the second separator 10b to a portion of the thermoplastic resin 12 formed on the other side of the second substrate 14b in the second seal portion 11b, and then cooling to harden the thermoplastic resin 12 and bond the pair of separators 10 to the seal portions 11.

[0021] In recent years, it has become clear that the thickness of the anode-side gas diffusion layer and the thickness of the cathode-side gas diffusion layer affect the power generation performance of a fuel cell. However, in conventional fuel cells, it was not possible to specify the thickness of the anode-side gas diffusion layer and the thickness of the cathode-side gas diffusion layer independently.

[0022] The fuel cell 1 of this embodiment includes an electrolyte membrane 3, a membrane electrode assembly 6 having electrodes 4, 5 arranged on one side and the other side of the electrolyte membrane 3, an anode-side gas diffusion layer 7 arranged on one side of the membrane electrode assembly 6, a cathode-side gas diffusion layer 8 arranged on the other side of the membrane electrode assembly 6, a sealing portion 11 including a thermoplastic resin 12 arranged on the end face side of the anode-side gas diffusion layer 7 and the end face side of the cathode-side gas diffusion layer 8, and a first separator 10a and a second separator 10b sandwiching the membrane electrode assembly 6 on which the anode-side gas diffusion layer 7 and the cathode-side gas diffusion layer 8 are arranged and the sealing portion 11, the first separator 10a arranged on the anode-side gas diffusion layer 7 side The electrolyte membrane 3 has an end 3a that protrudes outward from the end faces of the electrodes 4 and 5. The sealing portion 11 has a first substrate 14a that is arranged along the end face of the anode-side gas diffusion layer 7 between one side of the end 3a of the electrolyte membrane 3 and the first separator 10a, and a second substrate 14b that is arranged along the end face of the cathode-side gas diffusion layer 8 between the other side of the end 3a of the electrolyte membrane 3 and the second separator 10b. A portion of the thermoplastic resin 12 is formed on at least one side and the other side of the first substrate 14a and one side and the other side of the second substrate 14b.

[0023] This allows the thickness of the anode-side gas diffusion layer 7 and the thickness of the cathode-side gas diffusion layer 8 to be independently determined. In addition, in the fuel cell 1 of this embodiment, the sealing portion 11 is formed with a three-layer structure between one surface of the end portion 3a of the electrolyte membrane 3 and the first separator 10a, including a first substrate 14a arranged along the end surface of the anode-side gas diffusion layer 7 and thermoplastic resin 12 arranged on both surfaces of the first substrate 14a, and between the other surface of the end portion 3a of the electrolyte membrane 3 and the second separator 10b, including a second substrate 14b arranged along the end surface of the cathode-side gas diffusion layer 8 and thermoplastic resin 12 arranged on both surfaces of the second substrate 14b. This allows the amount of thermoplastic resin 12 to be reduced. Therefore, in a fuel cell manufacturing method for manufacturing a fuel cell 1, by applying a load to the first seal portion 11a and the second seal portion 11b through a pair of separators 10 consisting of a first separator 10a and a second separator 10b at a predetermined temperature, the first separator 10a and the thermoplastic resin 12 of the first seal portion 11a are bonded together, and also the second separator 10b and the thermoplastic resin 12 of the second seal portion 11b are bonded together, the heating time can be shortened, thereby improving productivity.

[0024] In addition, in the fuel cell 1 of this embodiment, the thickness of the first substrate 14a is set according to the thickness of the anode side gas diffusion layer 7, and the thickness of the second substrate 14b is set according to the thickness of the cathode side gas diffusion layer 8.

[0025] As a result, for example, if the thickness of the anode-side gas diffusion layer 7 is to be thicker than the thickness of the cathode-side gas diffusion layer 8, this can be achieved by setting the thickness of the first substrate 14a thicker than the thickness of the second substrate 14b. Also, if the thickness of the anode-side gas diffusion layer 7 and the thickness of the cathode-side gas diffusion layer 8 are to be the same, this can be achieved by setting the thickness of the first substrate 14a to be the same as the thickness of the second substrate 14b.

[0026] In addition, in the fuel cell 1 of this embodiment, the thermoplastic resin 12 of the sealing portion 11 bulges outward beyond the end 13a of the first separator 10a and the end 13b of the second separator 10b, and is formed so as to cover the end face of the electrolyte membrane 3 and part of one side and part of the other side of the end 3a of the electrolyte membrane 3.

[0027] As a result, even if an external force is applied to the end 13a of the first separator 10a and the end 13b of the second separator 10b, the first separator 10a and the second separator 10b are prevented from bending by the thermoplastic resin 12, and the pair of separators 10 will not come into contact (short circuit) with each other.

[0028] Next, the detailed structures of the first separator 10a and the second separator 10b will be described. The end 13a of the first separator 10a is formed so as to bend toward the second separator 10b, and the end 13b of the second separator 10b is formed so as to bend toward the first separator 10a. A portion of the thermoplastic resin 12 constituting the seal portion 11 bulges outward beyond the end 13a of the first separator 10a and the end 13b of the second separator 10b. In this embodiment, the end 13a of the first separator 10a is formed so as to bend toward the second separator 10b, but this is not necessarily limited to this. As long as the end 13a of the first separator 10a is formed so as to bend toward the second separator 10b, the end 13a of the first separator 10a may be formed so as to be curved toward the second separator 10b. Similarly, end 13b of second separator 10b is formed so as to bend toward first separator 10a, but is not necessarily limited to this. As long as end 13b of second separator 10b is formed so as to bend toward first separator 10a, end 13b of second separator 10b may be formed so as to curve toward first separator 10a.

[0029] Since a portion of the thermoplastic resin 12 constituting the seal portion 11 bulges outward beyond the end 13a of the first separator 10a and the end 13b of the second separator 10b, even if an external force is applied to the end 13a of the first separator 10a and the end 13b of the second separator 10b, the thermoplastic resin 12 prevents the end 13a of the first separator 10a and the end 13b of the second separator 10b from bending, and therefore the pair of separators 10 will not come into contact (short circuit) with each other.

[0030] The first separator 10a has a first outer inclined portion 15a that slopes away from the first substrate 14a from a first outer base end 16a located in a position facing the first substrate 14a toward the end 13a of the first separator 10a. At least a portion of the first outer inclined portion 15a is located in a position facing the first substrate 14a. The second separator 10b has a second outer inclined portion 15b that slopes away from the second substrate 14b from a second outer base end 16b located in a position facing the second substrate 14b toward the end 13b of the second separator 10b. At least a portion of the second outer inclined portion 15b is located in a position facing the second substrate 14b.

[0031] The first outer base end 16a is located closer to the inner end face than the center 17a between the inner end face of the first substrate 14a and the outer end face of the first substrate 14a. Here, the inner end face of the first substrate 14a refers to the end face on the anode-side gas diffusion layer 7 side (the right side in FIGS. 2 to 5), and the outer end face of the first substrate 14a refers to the end face opposite the inner end face of the first substrate 14a (the left side in FIGS. 2 to 5). The second outer base end 16b is located closer to the inner end face than the center 17b between the inner end face of the second substrate 14b and the outer end face of the second substrate 14b. Here, the inner end face of the second substrate 14b refers to the end face on the cathode-side gas diffusion layer 8 side (the right side in FIGS. 2 to 5), and the outer end face of the second substrate 14b refers to the end face opposite the inner end face of the second substrate 14b (the left side in FIGS. 2 to 5).

[0032] The first separator 10a has a first inner inclined portion 18a that slopes away from the first substrate 14a from a first inner base end 19a located in a position facing the first substrate 14a toward the anode-side gas diffusion layer 7, the first inner inclined portion 18a being closer to the anode-side gas diffusion layer 7 than the first outer inclined portion 15a. At least a portion of the first inner inclined portion 18a is located in a position facing the first substrate 14a. The second separator 10b has a second inner inclined portion 18b that slopes away from the second substrate 14b from a second inner base end 19b located in a position facing the second substrate 14b toward the cathode-side gas diffusion layer 8, the second inner inclined portion 18b being closer to the cathode-side gas diffusion layer 8 than the second outer inclined portion 15b. At least a portion of the second inner inclined portion 18b is located in a region facing the second base material 14b.

[0033] The first inner base end 19a is located closer to the inner end face than the center 17a between the inner end face of the first base material 14a and the outer end face of the first base material 14a. In this embodiment, the first inner base end 19a coincides with the first outer base end 16a. The second inner base end 19b is located closer to the inner end face than the center 17b between the inner end face of the second base material 14b and the outer end face of the second base material 14b. In this embodiment, the second inner base end 19b coincides with the second outer base end 16b.

[0034] An acute angle a1 formed between first inner inclined portion 18a and first base material 14a is larger than an acute angle b1 formed between first outer inclined portion 15a and first base material 14a. An acute angle a2 formed between second inner inclined portion 18b and second base material 14b is larger than an acute angle b2 formed between second outer inclined portion 15b and second base material 14b.

[0035] Next, a method for manufacturing the fuel cell 1 of this embodiment will be described with reference to Figures 3A and 3B. Figure 3A is an explanatory diagram conceptually illustrating the method for manufacturing the fuel cell 1 according to the first embodiment, and shows the cross-sectional structure of a fuel cell forming body 30 used in the manufacturing method of the fuel cell 1. The fuel cell 1 is manufactured by stacking each component and then applying a load (pressing) in the stacking direction. The fuel cell forming body 30 is a stack formed by stacking each component, and is the stack in a state before a load is applied in the stacking direction. The white arrow in Figure 3A indicates the direction of the load applied to the fuel cell forming body 30. Figure 3B shows the cross-sectional structure of the fuel cell forming body 30 used in the manufacturing method of the fuel cell 1 when a load is applied in the stacking direction.

[0036] The fuel cell forming body 30 includes an MEA 6, an anode-side gas diffusion layer 7 disposed on one side of the MEA 6, a cathode-side gas diffusion layer 8 disposed on the other side of the MEA 6, a first seal 11a disposed on one side of the end 3a of the electrolyte membrane 3 so as to follow the end face of the anode-side gas diffusion layer 7, a second seal 11b disposed on the other side of the end 3a of the electrolyte membrane 3 so as to follow the end face of the cathode-side gas diffusion layer 8, and a seal 11b disposed on one side of the anode-side gas diffusion layer 7 facing the MEA 6. The cathode-side gas diffusion layer 8 is provided on the other side of the MEA 6, and is also provided with a first separator 10a arranged on the side opposite to the side facing the end 3a of the electrolyte membrane 3, and with a first seal portion 11a arranged on one side of the end 3a of the electrolyte membrane 3, on the side opposite to the side facing the end 3a of the electrolyte membrane 3; and a second separator 10b arranged on the side opposite to the side facing the MEA 6, and with a second seal portion 11b arranged on the other side of the end 3a of the electrolyte membrane 3, on the side opposite to the side facing the electrolyte membrane 3.

[0037] The outline of the method for manufacturing the fuel cell 1 is as follows. (A) Each member required for the fuel cell forming body 30, which is a laminate, is prepared. (B) Each member is stacked to prepare a fuel cell forming body 30. (C) A load is applied to the fuel cell forming body 30 in the stacking direction.

[0038] Specifically, the method for manufacturing the fuel cell 1 includes the following steps. (A) Prepare an MEA 6 in which an anode-side catalytic electrode 4 is arranged on one side of an electrolyte membrane 3 and a cathode-side catalytic electrode 5 is arranged on the other side of the electrolyte membrane 3, an anode-side gas diffusion layer 7, a first seal portion 11a, a cathode-side gas diffusion layer 8, a second seal portion 11b, and a pair of separators 10 consisting of a first separator 10a and a second separator 10b. (B1) An anode-side gas diffusion layer 7 is disposed on one surface of the MEA 6. (B2) On the other surface of the MEA 6, a cathode side gas diffusion layer 8 is disposed. (B3) A first seal portion 11a is disposed on one surface of the end portion 3a of the electrolyte membrane 3 so as to fit along the end surface of the anode side gas diffusion layer . (B4) A second seal portion 11b is disposed on the other surface of the end portion 3a of the electrolyte membrane 3 so as to fit along the end surface of the cathode side gas diffusion layer 8. (B5) A first separator 10a is arranged on the side opposite to the side facing the MEA 6 of the anode side gas diffusion layer 7 arranged on one side of the MEA 6, and on the side opposite to the side facing the electrolyte membrane 3 of the first seal part 11a arranged on one side of the end 3a of the electrolyte membrane 3. (B6) A second separator 10b is arranged on the side opposite to the side facing the MEA 6 of the cathode side gas diffusion layer 8 arranged on the other side of the MEA 6, and on the side opposite to the side facing the electrolyte membrane 3 of the second seal part 11b arranged on the other side of the end 3a of the electrolyte membrane 3. (C1) At a predetermined temperature, a load is applied to the first seal portion 11a and the anode-side gas diffusion layer 7 and the second seal portion 11b and the cathode-side gas diffusion layer 8 via a pair of separators 10 consisting of a first separator 10a and a second separator 10b. (C2) A load is applied to the first seal portion 11a and the anode-side gas diffusion layer 7 and the second seal portion 11b and the cathode-side gas diffusion layer 8 via the first separator 10a and the second separator 10b, thereby joining the first separator 10a and the anode-side gas diffusion layer 7, bonding the first separator 10a and the thermoplastic resin 12 formed on one surface of the first substrate 14a in the first seal portion 11a, and bonding the second separator 10b and the cathode-side gas diffusion layer 8. The second separator 10b and the thermoplastic resin 12 formed on the other surface of the second substrate 14b in the second seal portion 11b are bonded together, and the thermoplastic resin 12 formed on both surfaces of the first substrate 14a in the first seal portion 11a bulges outward beyond the end 13a of the first separator 10a, and the thermoplastic resin 12 formed on both surfaces of the second substrate 14b in the second seal portion 11b bulges outward beyond the end 13b of the second separator 10b (see Figure 3B). (C3) The thermoplastic resin 12 formed on both surfaces of the first substrate 14a at the first seal portion 11a that bulges outward from the end portion 13a of the first separator 10a and the thermoplastic resin 12 formed on both surfaces of the second substrate 14b at the second seal portion 11b that bulges outward from the end portion 13b of the second separator 10b are welded together so as to cover the end surface of the electrolyte membrane 3, a portion of one surface of the end portion 3a of the electrolyte membrane 3, and a portion of the other surface (see Figure 2). (C4) The first separator 10a and the thermoplastic resin 12 formed on one side of the first substrate 14a in the first seal portion 11a are bonded together, and the second separator 10b and the thermoplastic resin 12 formed on the other side of the second substrate 14b in the second seal portion 11b are bonded together, and the thermoplastic resin 12 formed on both sides of the first substrate 14a in the first seal portion 11a and the thermoplastic resin 12 formed on both sides of the second substrate 14b in the second seal portion 11b are welded together so as to cover the end face of the electrolyte membrane 3, part of one side of the end 3a of the electrolyte membrane 3, and part of the other side, and then cooled to harden the thermoplastic resin 12.

[0039] Next, the detailed structure of the fuel cell forming body 30 will be described with reference to FIG. 4. FIG. 4 shows the cross-sectional structure of the fuel cell forming body 30. Regarding each component of the fuel cell forming body 30, components that have already been described will be omitted. The fuel cell forming body 30 is a stack formed by stacking various components, and is a stack in a state before a load is applied in the stacking direction (before pressing). A first flow path 21a is formed on the surface of the first separator 10a facing the anode-side gas diffusion layer 7 for supplying a reactant gas to the adjacent anode-side gas diffusion layer 7. A second flow path 21b is formed on the surface of the second separator 10b facing the cathode-side gas diffusion layer 8 for supplying a reactant gas to the adjacent cathode-side gas diffusion layer 8. In the fuel cell forming body 30, the depth dimension of the first flow path 21a in the thickness direction of the first separator 10a is set to d1. In the fuel cell forming body 30, the depth dimension of the second flow path 21b in the thickness direction of the second separator 10b is set to d2. The depth dimension d1 of the first flow path 21a and the depth dimension d2 of the second flow path 21b are dimensions before a load is applied to the fuel cell forming body 30 in the stacking direction.

[0040] In the fuel cell forming body 30, the thickness of the thermoplastic resin 12 formed on one surface of the first substrate 14a at the first seal portion 11a (hereinafter referred to as the thickness of the thermoplastic resin 12 at the first seal portion 11a) is set to t1. The thermoplastic resin 12 formed on one surface of the first substrate 14a at the first seal portion 11a is the thermoplastic resin 12 disposed between the first substrate 14a and the first separator 10a. In the fuel cell forming body 30, the thickness of the thermoplastic resin 12 formed on the other surface of the second substrate 14b at the second seal portion 11b (hereinafter referred to as the thickness of the thermoplastic resin 12 at the second seal portion 11b) is set to t2. The thermoplastic resin 12 formed on the other surface of the second substrate 14b at the second seal portion 11b is the thermoplastic resin 12 disposed between the second substrate 14b and the second separator 10b. The thickness dimension t1 of the thermoplastic resin 12 of the first seal portion 11a and the thickness dimension t2 of the thermoplastic resin 12 of the second seal portion 11b are dimensions before a load is applied to the fuel cell formation body 30 in the stacking direction.

[0041] The thickness t1 of the thermoplastic resin 12 in the first seal portion 11a is set larger than the depth d1 of the first flow path 21a, and the thickness t2 of the thermoplastic resin 12 in the second seal portion 11b is set larger than the depth d2 of the second flow path 21b.

[0042] As a result, when a load is applied to the fuel cell forming body 30 in the stacking direction to join the first separator 10a and the anode-side gas diffusion layer 7, the thermoplastic resin 12 arranged between the first substrate 14a of the first seal portion 11a and the first separator 10a can be reliably caused to bulge outward beyond the end 13a of the first separator 10a, and the thermoplastic resin 12 arranged between the second substrate 14b of the second seal portion 11b and the second separator 10b can be caused to bulge outward beyond the end 13b of the second separator 10b, so that the thermoplastic resin 12 of the first seal portion 11a and the thermoplastic resin 12 of the second seal portion 11b can be welded together to cover the end face of the electrolyte membrane 3.

[0043] 5A to 5C, the mechanism by which a load is applied to the fuel cell forming body 30 in the stacking direction, thereby welding the thermoplastic resin 12 of the first seal portion 11a and the thermoplastic resin 12 of the second seal portion 11b to cover the end face of the electrolyte membrane 3, will be described. FIG. 5A is an explanatory diagram schematically showing the initial stage in which a load is applied to the fuel cell forming body 30 in the stacking direction. FIG. 5B is an explanatory diagram schematically showing the second stage in which a load is applied to the fuel cell forming body 30 in the stacking direction. FIG. 5C is an explanatory diagram schematically showing the final stage in which a load is applied to the fuel cell forming body 30 in the stacking direction. The two-dot chain lines shown in FIGS. 5A to 5C indicate the position of the first separator 10a moved toward the electrolyte membrane 3 by applying a load to the fuel cell forming body 30 in the stacking direction. 5A to 5C, the first separator 10a side is described, and the description of the second separator 10b side is omitted because it is the same as the first separator 10a side.

[0044] In the initial stage shown in FIG. 5A, the pressure on the first separator 10a pushes the thermoplastic resin 12 to the left and right, as indicated by the open arrows, with the dashed line as the boundary. The amount of thermoplastic resin 12 pushed to the left and right corresponds to the area of ​​the shaded portion shown above the first separator 10a, indicated by the two-dot chain line. The stage shown in FIG. 5B is the second stage, in which the pressure on the first separator 10a has further progressed. As the pressure on the first separator 10a progresses, the difference in the amount of thermoplastic resin 12 pushed to the left and right, as indicated by the open arrows, with the dashed line as the boundary becomes more pronounced. The amount of thermoplastic resin 12 pushed to the left of the dashed line is greater than the amount of thermoplastic resin 12 pushed to the right of the dashed line. The amount of thermoplastic resin 12 pushed to the left and right corresponds to the area of ​​the shaded portion shown above the first separator 10a, indicated by the two-dot chain line. The stage shown in Figure 5C is the final stage, where the pressure on the first separator 10a has progressed further. The pressure on the first separator 10a further extrudes the thermoplastic resin 12 to the left and right, as indicated by the white arrows, with the dashed-dotted line as the boundary. The thickness dimension t1 of the thermoplastic resin 12 is set larger than the depth dimension d1 of the first flow path 21a in the first separator 10a (t1>d1). By setting t1>d1, the first separator 10a is in close contact directly above the thermoplastic resin 12, and an amount of thermoplastic resin 12 equivalent to the area of ​​the shaded portion shown above the first separator 10a by the two-dot-dash line is extruded. Because the only direction in which the thermoplastic resin 12 equivalent to the area of ​​the shaded portion to the left of the dashed-dotted line can be extruded is outward to the left, the thermoplastic resin 12 equivalent to the area of ​​the shaded portion to the left of the dashed-dotted line is reliably extruded outward. This allows the end face of the electrolyte membrane 3 to be welded together so as to be covered by the thermoplastic resin 12 of the first seal portion 11a and the thermoplastic resin 12 of the second seal portion 11b.

[0045] Next, a fuel cell forming body 31 according to a second embodiment of the fuel cell 1 will be described with reference to FIG. 6. FIG. 6 shows the cross-sectional configuration of the fuel cell forming body 31 according to the second embodiment. The fuel cell forming body 31 is a stack of various components, and is a stack before a load is applied in the stacking direction (before pressing). The fuel cell forming body 30 according to the first embodiment differs from the fuel cell forming body 31 according to the second embodiment in that, in the fuel cell forming body 30 according to the first embodiment, the first inner base end 19a coincides with the first outer base end 16a, and the second inner base end 19b coincides with the second outer base end 16b. However, in the fuel cell forming body according to the second embodiment, the first inner base end 19a does not coincide with the first outer base end 16a, and the second inner base end 19b does not coincide with the second outer base end 16b. The other configuration of the fuel cell forming body 31 according to the second embodiment is the same as the other configuration of the fuel cell forming body 30 according to the first embodiment, and therefore a description of the other configuration of the fuel cell forming body 31 according to the second embodiment will be omitted. Furthermore, in the fuel cell forming body 31 according to the second embodiment, the numbering of the configuration that is common to the configuration of the fuel cell forming body 30 according to the first embodiment will be the same as the numbering of the fuel cell forming body 30 according to the first embodiment.

[0046] The first outer inclined portion 15a has a first outer base end 16a, which is the base end of the first outer inclined portion 15a. Although not shown in FIG. 5, the first outer base end 16a is located closer to the inner end face than a center 17a between the inner end face of the first base material 14a and the outer end face of the first base material 14a. The second outer inclined portion 15b has a second outer base end 16b, which is the base end of the second outer inclined portion 15b. Although not shown in FIG. 5, the second outer base end 16b is located closer to the inner end face than a center 17b between the inner end face of the second base material 14b and the outer end face of the second base material 14b.

[0047] The first inner inclined portion 18a has a first inner base end 19a, which is the base end of the first inner inclined portion 18a. Although not shown in FIG. 5, the first inner base end 19a is located closer to the inner end face than the center 17a between the inner end face of the first base material 14a and the outer end face of the first base material 14a. The first inner base end 19a does not coincide with the first outer base end 16a, and the first inner base end 19a is located closer to the inner end face of the first base material 14a than the first outer base end 16a. The second inner inclined portion 18b has a second inner base end 19b, which is the base end of the second inner inclined portion 18b. Although not shown in FIG. 5, the second inner base end 19b is located closer to the inner end face than the center 17b between the inner end face of the second base material 14b and the outer end face of the second base material 14b. The second inner base end 19b does not coincide with the second outer base end 16b, and the second inner base end 19b is located closer to the inner end face of the second base material 14b than the second outer base end 16b.

[0048] In the above-described fuel cell 1, the first separator 10a has a first outer inclined portion 15a that slopes away from the first substrate 14a from the first outer base end 16a located at the position opposite the first substrate 14a toward the end 13a of the first separator 10a, and the second separator 10b has a second outer inclined portion 15b that slopes away from the second substrate 14b from the second outer base end 16b located at the position opposite the second substrate 14b toward the end 13b of the second separator 10b.

[0049] As a result, when a load is applied to the fuel cell forming body 30 in the stacking direction to bond the first separator 10a and the anode-side gas diffusion layer 7 in the manufacturing method of the fuel cell 1, the thermoplastic resin 12 disposed between the first substrate 14a of the first seal portion 11a and the first separator 10a can be caused to bulge outward beyond the end 13a of the first separator 10a, and the thermoplastic resin 12 disposed between the second substrate 14b of the second seal portion 11b and the second separator 10b can be caused to bulge outward beyond the end 13b of the second separator 10b, as shown in Fig. 3B . Therefore, the thermoplastic resin 12 of the first seal portion 11a and the thermoplastic resin 12 of the second seal portion 11b can be welded to cover the end face of the electrolyte membrane 3, a portion of one side of the end 3a of the electrolyte membrane 3, and a portion of the other side of the end 3a. As a result, even if an external force is applied to the end 13a of the first separator 10a and the end 13b of the second separator 10b, the end 13a of the first separator 10a and the end 13b of the second separator 10b are prevented from bending by the thermoplastic resin 12, and therefore the pair of separators 10 will not come into contact (short circuit) with each other.

[0050] In the fuel cell 1 described above, the first outer inclined portion 15a has a first outer base end 16a which is the base end of the first outer inclined portion 15a, and the second outer inclined portion 15b has a second outer base end 16b which is the base end of the second outer inclined portion 15b, the first outer base end 16a being located closer to the end face on the anode side gas diffusion layer 7 side than a center 17a between the end face of the first substrate 14a on the anode side gas diffusion layer 7 side and the outer end face of the first substrate 14a, and the second outer base end 16b being located closer to the end face on the cathode side gas diffusion layer 8 side than a center 17b between the end face of the second substrate 14b on the cathode side gas diffusion layer 8 side and the outer peripheral end face of the second substrate 14b.

[0051] As a result, in the manufacturing method of the fuel cell 1, when a load is applied to the fuel cell forming body 30 in the stacking direction to bond the first separator 10a and the anode-side gas diffusion layer 7, a larger amount of the thermoplastic resin 12 arranged between the first substrate 14a of the first seal portion 11a and the first separator 10a can be extruded toward the end 13a of the first separator 10a, causing the thermoplastic resin 12 to bulge outward from the end 13a of the first separator 10a. Also, a larger amount of the thermoplastic resin 12 arranged between the second substrate 14b of the second seal portion 11b and the second separator 10b can be extruded toward the end 13b of the second separator 10b, causing the thermoplastic resin 12 to bulge outward from the end 13b of the second separator 10b. 2, the thermoplastic resin 12 of the first seal portion 11a and the thermoplastic resin 12 of the second seal portion 11b can be welded to cover the end face of the electrolyte membrane 3, a portion of one side of the end portion 3a of the electrolyte membrane 3, and a portion of the other side of the end portion 3a of the electrolyte membrane 3. As a result, even if an external force is applied to the end portion 13a of the first separator 10a and the end portion 13b of the second separator 10b, the thermoplastic resin 12 prevents the end portion 13a of the first separator 10a and the end portion 13b of the second separator 10b from bending, and therefore the pair of separators 10 will not come into contact (short circuit) with each other.

[0052] In the fuel cell 1 of this embodiment, the first separator 10a has a first inner inclined portion 18a that is inclined away from the first substrate 14a from a first inner base end 19a located in a position facing the first substrate 14a toward the anode side gas diffusion layer 7, and the first inner inclined portion 18a is located closer to the anode side gas diffusion layer 7 than the first outer inclined portion 15a. The second separator 10b has a second inner inclined portion 19b that is inclined away from the second substrate 14b from a second inner base end 19b located in a position facing the second substrate 14b toward the cathode side gas diffusion layer 8. The second inner inclined portion 18b is inclined away from the first inner inclined portion 18a and is located closer to the cathode side gas diffusion layer 8 than the second outer inclined portion 15b, and the acute angle a1 formed between the first inner inclined portion 18a and the first substrate 14a is larger than the acute angle b1 formed between the first outer inclined portion 15a and the first substrate 14a, and the acute angle a2 formed between the second inner inclined portion 18b and the second substrate 14b is larger than the acute angle b2 formed between the second outer inclined portion 15b and the second substrate 14b.

[0053] As a result, in the manufacturing method of the fuel cell 1, when a load is applied to the fuel cell forming body 30 in the stacking direction to bond the first separator 10a and the anode-side gas diffusion layer 7, a larger amount of the thermoplastic resin 12 arranged between the first substrate 14a of the first seal portion 11a and the first separator 10a can be extruded toward the end 13a of the first separator 10a, causing the thermoplastic resin 12 to bulge outward from the end 13a of the first separator 10a. Also, a larger amount of the thermoplastic resin 12 arranged between the second substrate 14b of the second seal portion 11b and the second separator 10b can be extruded toward the end 13b of the second separator 10b, causing the thermoplastic resin 12 to bulge outward from the end 13b of the second separator 10b. 2, the thermoplastic resin 12 of the first seal portion 11a and the thermoplastic resin 12 of the second seal portion 11b can be welded to cover the end face of the electrolyte membrane 3, a portion of one side of the end portion 3a of the electrolyte membrane 3, and a portion of the other side of the end portion 3a of the electrolyte membrane 3. As a result, even if an external force is applied to the end portion 13a of the first separator 10a and the end portion 13b of the second separator 10b, the thermoplastic resin 12 prevents the end portion 13a of the first separator 10a and the end portion 13b of the second separator 10b from bending, and therefore the pair of separators 10 will not come into contact (short circuit) with each other.

[0054] The above describes the embodiments of the present invention and their modifications, but the present invention is not limited to the above-described embodiments and modifications, and further modifications and changes are possible based on the technical concept of the present invention. [Explanation of symbols]

[0055] 1...fuel cell 2...Fuel cell 3...Electrolyte membrane 3a...End of electrolyte membrane 4...Anode side catalytic electrode 5...Cathode catalytic electrode 6...Membrane electrode assembly (MEA) 7...Anode side gas diffusion layer 8...Cathode side gas diffusion layer 9...Membrane electrode gas diffusion layer assembly (MEGA) 10...Separator 10a...First separator 10b...Second separator 11...Sealing part 11a...first seal portion 11b...second seal portion 12...Thermoplastic resin 13a...end 13b...end part 14a...first substrate 14b...Second substrate 15a...first outer inclined portion 15b...second outer inclined portion 16a...First outer proximal end 16b…Second outer proximal end 17a…center 17b…center 18a...first inner inclined portion 18b...Second inner inclined portion 19a...first inner proximal end 19b…Second inner proximal end 21a...First flow path 21b...Second flow path 30...Fuel cell forming body 31...Fuel cell forming body

Claims

1. A fuel cell, a membrane electrode assembly having an electrolyte membrane and electrodes disposed on one surface and the other surface of the electrolyte membrane; an anode-side gas diffusion layer disposed on one surface of the membrane electrode assembly; a cathode-side gas diffusion layer disposed on the other surface of the membrane electrode assembly; a sealing portion, which is disposed on an end surface side of the anode-side gas diffusion layer and an end surface side of the cathode-side gas diffusion layer, and which contains a thermoplastic resin; a first separator and a second separator that sandwich the membrane electrode assembly, on which the anode-side gas diffusion layer and the cathode-side gas diffusion layer are arranged, and the seal portion, the first separator being arranged on the anode-side gas diffusion layer side and the second separator being arranged on the cathode-side gas diffusion layer side; Equipped with an end of the electrolyte membrane protrudes outward beyond an end surface of the electrode; the sealing portion includes a first substrate disposed along an end face of the anode-side gas diffusion layer between one surface of the end of the electrolyte membrane and the first separator, and a second substrate disposed along an end face of the cathode-side gas diffusion layer between the other surface of the end of the electrolyte membrane and the second separator, A fuel cell characterized in that a portion of the thermoplastic resin is formed on at least one side and the other side of the first substrate and one side and the other side of the second substrate.

2. 2. The fuel cell according to claim 1, wherein a portion of the thermoplastic resin bulges outward beyond the end faces of the first separator and the second separator, and is formed so as to cover the end faces of the electrolyte membrane and a portion of one side and a portion of the other side of the end of the electrolyte membrane.

3. an end of the first separator is formed to bend toward the second separator, and an end of the second separator is formed to bend toward the first separator; 3. The fuel cell according to claim 2, wherein the thermoplastic resin bulges outward beyond the ends of the first separator and the second separator.

4. the first separator has a first outer inclined portion that is inclined away from the first substrate from a first outer base end located in a portion facing the first substrate toward an end of the first separator, 4. The fuel cell according to claim 3, wherein the second separator has a second outer inclined portion that slopes away from the second substrate from a second outer base end located at a position facing the second substrate toward the end of the second separator.

5. the first outer base end is located closer to the end face of the anode side gas diffusion layer than a center between the end face of the first substrate on the anode side gas diffusion layer side and an outer end face of the first substrate, 5. The fuel cell according to claim 4, wherein the second outer base end is located closer to the end face of the cathode side gas diffusion layer than the center between the end face of the second substrate on the cathode side gas diffusion layer side and the outer end face of the second substrate.

6. the first separator has a first inner inclined portion that inclines away from the first substrate from a first inner base end located at a portion facing the first substrate toward the anode-side gas diffusion layer, the first inner inclined portion being closer to the anode-side gas diffusion layer than the first outer inclined portion; the second separator has a second inner inclined portion that inclines from a first inner base end located in a region facing the second substrate toward the cathode-side gas diffusion layer, the second inner inclined portion being closer to the cathode-side gas diffusion layer than the second outer inclined portion; an acute angle formed between the first inner inclined portion and the first base material is larger than an acute angle formed between the first outer inclined portion and the first base material, 6. The fuel cell according to claim 5, wherein the acute angle formed by the second inner inclined portion and the second base material is larger than the acute angle formed by the second outer inclined portion and the second base material.

7. the thickness of the first substrate is set according to the thickness of the anode-side gas diffusion layer; 7. The fuel cell according to claim 1, wherein the thickness of the second substrate is set in accordance with the thickness of the cathode-side gas diffusion layer.

8. A method for manufacturing the fuel cell according to any one of claims 1 to 6, comprising the steps of: preparing the membrane electrode assembly, the anode-side gas diffusion layer, a first sealing part having the first substrate and a portion of the thermoplastic resin formed on one surface and the other surface of the first substrate, the cathode-side gas diffusion layer, a second sealing part having the second substrate and a portion of the thermoplastic resin formed on one surface and the other surface of the second substrate, the first separator, and the second separator; the anode-side gas diffusion layer is disposed on one surface of the membrane electrode assembly; the cathode-side gas diffusion layer is disposed on the other surface of the membrane electrode assembly; the first seal portion is disposed on one surface of the end portion of the electrolyte membrane along an end surface of the anode-side gas diffusion layer; the second seal portion is disposed on the other surface of the end of the electrolyte membrane along the end surface of the cathode-side gas diffusion layer; disposing the first separator on a surface of the anode-side gas diffusion layer disposed on one surface of the membrane electrode assembly opposite to a surface facing the membrane electrode assembly and on a surface of the first seal disposed on one surface of the end of the electrolyte membrane opposite to a surface facing the end of the electrolyte membrane, and disposing the second separator on a surface of the cathode-side gas diffusion layer disposed on the other surface of the membrane electrode assembly opposite to a surface facing the membrane electrode assembly and on a surface of the second seal disposed on the other surface of the end of the electrolyte membrane opposite to a surface facing the electrolyte membrane; applying a load to the first seal and the anode-side gas diffusion layer, and the second seal and the cathode-side gas diffusion layer, via the first separator and the second separator, at a predetermined temperature, to bond the first separator to the thermoplastic resin formed on one surface of the first substrate in the first seal and to bond the second separator to the thermoplastic resin formed on the other surface of the second substrate in the second seal, causing the thermoplastic resin in the first seal to bulge outward from the end face of the first separator and the thermoplastic resin in the second seal to bulge outward from the end face of the second separator, and welding the thermoplastic resin in the first seal and the thermoplastic resin in the second seal to the end face of the electrolyte membrane and to cover a portion of one surface and a portion of the other surface of the end of the electrolyte membrane; 1. A method for manufacturing a fuel cell, comprising:

9. A fuel cell forming body used in the method for manufacturing a fuel cell according to claim 8, the membrane electrode assembly, the anode side gas diffusion layer, the cathode side gas diffusion layer, the first seal portion, the second seal portion, the first separator, and the second separator, a first flow path for supplying a reactant gas to the adjacent anode-side gas diffusion layer is formed on a surface of the first separator facing the anode-side gas diffusion layer; a second flow path for supplying a reactant gas to the adjacent cathode-side gas diffusion layer is formed on a surface of the second separator facing the cathode-side gas diffusion layer; a dimension in a thickness direction of the thermoplastic resin formed on one surface of the first base material at the first seal portion before the load is applied to the first seal portion is larger than a depth dimension of the first flow path in the thickness direction of the first separator, A fuel cell forming body, characterized in that the thickness dimension of the thermoplastic resin formed on the other surface of the second substrate at the second seal portion before a load is applied to the second seal portion is larger than the depth dimension of the second flow path in the thickness direction of the second separator.

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