Manufacturing method of fuel battery

Abstract

To suppress the formation of bubbles in an adhesion layer even in the case of adapting a pressure-sensitive type adhesive agent.SOLUTION: A manufacturing method of a fuel battery comprises the steps of: forming an adhesion layer by applying a pressure-sensitive type adhesive agent along a defined seal line on a front surface of a support frame for supporting a membrane electrode composite; making a separator approach the front surface of the support frame until it comes into contact with the adhesion layer applied on the support frame; and boding the support frame and the separator with each other by applying a compression force to the support frame and the separator that are in contact via the adhesion layer. In the step of making approach, a distance between the front surface of the adhesion layer and the front surface of the separator that is opposite to the front surface becomes minimum at one specific portion in a cross section that is vertical to a long direction of the seal line, and is monotonously increased as separating from a width direction of the seal line from the one portion.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a method for manufacturing a fuel cell. [Background technology]

[0002] Patent Document 1 describes a method for manufacturing a fuel cell, in which a separator is attached, using an adhesive, to the surface of a support frame that supports a membrane electrode assembly. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-113391 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, a heat-sensitive adhesive has been used in the manufacture of fuel cells. Instead, it is conceivable to use a pressure-sensitive adhesive. However, a heat-sensitive adhesive undergoes a phase change from solid to liquid during the bonding process, whereas a pressure-sensitive adhesive does not undergo such a phase change. Therefore, there is a risk that air bubbles trapped between the adhesive layer formed by the pressure-sensitive adhesive and the separator will remain in the adhesive layer.

[0005] In view of the above circumstances, this specification provides a technique for suppressing the formation of air bubbles in an adhesive layer even when a pressure-sensitive adhesive is used. [Means for solving the problem]

[0006] The technology disclosed in this specification is embodied in a method for manufacturing a fuel cell. The method for manufacturing a fuel cell includes the steps of applying a pressure-sensitive adhesive along a predetermined seal line to a surface of a support frame supporting a membrane electrode assembly to form an adhesive layer, moving a separator toward the surface of the support frame until the separator comes into contact with the adhesive layer formed on the support frame, and applying a compressive force to the support frame and the separator that are in contact with each other via the adhesive layer to bond the support frame and the separator to each other. In the moving toward each other step, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the adhesive layer and the surface of the separator facing the surface of the adhesive layer is minimum at a specific point and increases monotonically with distance from the specific point in the width direction of the seal line.

[0007] In the above-mentioned method for manufacturing a fuel cell, the support frame and the separator are bonded to each other through an adhesive layer formed of a pressure-sensitive adhesive. More specifically, first, a pressure-sensitive adhesive is applied to the surface of the support frame along a predetermined seal line to form an adhesive layer. Then, the separator is moved toward the surface of the support frame until the separator contacts the adhesive layer on the support frame. At this time, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the adhesive layer and the surface of the separator facing the adhesive layer is minimum at a specific point, and increases monotonically as it moves away from the specific point in the width direction of the seal line. Then, a compressive force is applied to the support frame and the separator, so that the support frame and the separator are bonded to each other through the adhesive layer. According to this configuration, the adhesive layer and the separator are sequentially brought into contact with each other along the width direction of the seal line from the specific point where the distance between the surface of the adhesive layer and the surface of the separator is minimum. Therefore, it is possible to suppress the trapping of air bubbles between the adhesive layer and the separator. In addition, even if air bubbles are trapped between the adhesive layer and the separator, the air bubbles can be pushed out from a specific location along the width direction of the seal line, thereby preventing air bubbles from being formed in the adhesive layer formed of the pressure-sensitive adhesive.

[0008] In a second aspect, in the first aspect, in the step of forming the adhesive layer, the adhesive may be applied so that the thickness of the adhesive layer is maximum at one point in a cross section perpendicular to the longitudinal direction of the seal line, and decreases monotonically as it moves away from the one point in the width direction of the seal line. According to this configuration, by adjusting the thickness of the adhesive layer in a cross section perpendicular to the longitudinal direction of the seal line, it is possible to suppress the formation of air bubbles in the adhesive layer.

[0009] In a third aspect, in the first or second aspect, in the step of forming the adhesive layer, the adhesive may be applied so that the adhesive layer has a symmetrical shape in a cross section perpendicular to the longitudinal direction of the seal line. With this configuration, in a cross section perpendicular to the longitudinal direction of the seal line, the adhesive layer and the separator gradually come into contact with each other from the center of the adhesive layer toward both sides in the width direction. Therefore, it is possible to prevent air bubbles from being trapped between the adhesive layer and the separator, and even if air bubbles are trapped between the adhesive layer and the separator, the air bubbles can be pushed out from the center toward both sides in the width direction of the seal line.

[0010] Alternatively, in another embodiment, the one point where the thickness of the adhesive is maximum in a cross section perpendicular to the longitudinal direction of the seal line may be located at one end of the seal line in the width direction. In this case, the thickness of the adhesive layer may monotonically decrease from the one point toward the other end. With such a configuration, it is possible to prevent air bubbles from being trapped between the adhesive layer and the separator, and even if air bubbles are trapped between the adhesive layer and the separator, the air bubbles can be pushed out from one end of the seal line toward the other end.

[0011] In a fourth aspect, in any one of the first to third aspects, in the approaching step, in a cross section perpendicular to the longitudinal direction of the seal line, the surface of the separator facing the adhesive layer may protrude toward the adhesive layer, and the amount of protrusion may be maximum at one point and monotonically decrease as it moves away from the one point in the width direction of the seal line. According to this configuration, by providing a protruding portion on the separator, it is possible to suppress the formation of air bubbles in the adhesive layer.

[0012] In any of the above-mentioned aspects, the width of the adhesive layer in a cross section perpendicular to the longitudinal direction of the seal line may be 10 mm or less. In addition, or instead, the difference between the maximum thickness and the minimum thickness of the adhesive layer in a cross section perpendicular to the longitudinal direction of the seal line may be 20 micrometers or more. According to these configurations, the formation of air bubbles in the adhesive layer can be more effectively suppressed.

[0013] In any of the above-mentioned embodiments, the viscoelastic properties of the adhesive constituting the adhesive layer are 5 Mpa to 10 7 Even when such an adhesive is used, the technology disclosed in this specification can prevent air bubbles from being formed in the adhesive layer.

[0014] The technology disclosed in this specification is also embodied in a manufacturing method of another fuel cell. This manufacturing method of a fuel cell includes the steps of applying a pressure-sensitive adhesive along a predetermined seal line to the surface of a first separator constituting a fuel cell to form an adhesive layer, moving a second separator constituting another fuel cell to the surface of the first separator until the second separator comes into contact with the adhesive layer formed on the first separator, and applying a compressive force to the first separator and the second separator that are in contact with each other via the adhesive layer to bond the first separator and the second separator to each other. In the moving-together step, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the adhesive layer and the surface of the second separator facing the surface of the adhesive layer is minimum at a specific point and increases monotonically as it moves away from the specific point in the width direction of the seal line.

[0015] In the above-mentioned fuel cell manufacturing method, a first separator constituting a fuel cell and a second separator constituting another fuel cell are bonded to each other via an adhesive layer formed of a pressure-sensitive adhesive. That is, in the above-mentioned fuel cell manufacturing method, the adherends bonded via the adhesive layer are changed compared to the above-mentioned fuel cell manufacturing method. Even with this configuration, the adhesive layer and the second separator come into contact with each other in sequence along the width direction of the seal line from a specific point where the distance between the surface of the adhesive layer and the surface of the second separator is the smallest. Therefore, it is possible to suppress the formation of air bubbles in the adhesive layer. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a fuel cell 10 according to an embodiment. [Diagram 2] FIG. 2 is an exploded view showing a schematic configuration of a fuel cell 12. [Diagram 3] 1 is a diagram showing an adhesive layer 24 applied along a defined seal line on the surface of a support frame 20. That is, the applied area of ​​the adhesive layer 24 indicates the defined seal line. [Figure 4]Figures 4(A)-(C) show the flow of the manufacturing method of the fuel cell 10. Figure 4(A) is a cross-sectional view taken along line IV-IV. Figure 4(B) shows the step of bringing the separators 16, 18 close to the surface of the support frame 20. Figure 4(C) shows that the support frame 20 and the separators 16, 18 are bonded to each other via the adhesive layers 24, 26. [Diagram 5] 5(A)-(C) show several modified examples of adhesive layers 24, 26, each of which corresponds to the cross-sectional view of FIG. 4(A). [Figure 6] 6(A) and (B) show a modified example in which protrusions 32 are provided on separators 16 and 18 instead of adhesive layers 24 and 26, and each corresponds to the cross-sectional view of FIG. 4(A). [Figure 7] 7(A)-(C) show the flow of another method for manufacturing the fuel cell 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A fuel cell 10 and a manufacturing method thereof according to an embodiment will be described with reference to the drawings. As shown in FIG. 1, the fuel cell 10 includes a plurality of fuel cell units 12. Each fuel cell unit 12 is arranged parallel to the X-axis and Z-axis, and the plurality of fuel cell units 12 are stacked along the Y-axis. As will be described in detail later, each fuel cell unit 12 is a component capable of generating electricity independently. The fuel cell 10 can be used in, but is not limited to, a vehicle that uses a fuel cell as a power source, such as a fuel cell car.

[0018] As shown in FIG. 2, each fuel cell 12 includes a membrane electrode assembly (MEA) 14, an anode-side separator 16, a cathode-side separator 18, and a support frame 20. Although not shown, the MEA 14 includes an electrolyte membrane, an anode catalyst layer provided on one surface of the electrolyte membrane, and a catalyst layer provided on the other surface of the electrolyte membrane. The MEA 14 is supported by the support frame 20. The MEA 14, together with the support frame 20, is disposed between the anode-side separator 16 and the cathode-side separator 18. Although not particularly limited, each fuel cell 12 may further include an anode-side gas diffusion layer and a cathode-side gas diffusion layer on both sides of the MEA 14. That is, the MEA 14 may constitute a membrane electrode and gas diffusion layer assembly (MEGA) together with the anode-side gas diffusion layer and the cathode-side gas diffusion layer.

[0019] The anode-side separator 16 and the cathode-side separator 18 are plate-shaped members made of a gas-impermeable conductive material. Although not particularly limited, each of the separators 16 and 18 may be made of a metal plate such as titanium or stainless steel. Each of the separators 16 and 18 has six manifold holes 28a-28f. These manifold holes 28a-28f constitute manifolds 30a, 30c, and 30e that supply hydrogen gas, air, and a cooling medium to each of the fuel cells 12, respectively, and manifolds 30b, 30d, and 30f that collect unreacted hydrogen gas, unreacted air, and a cooling medium from each of the fuel cells 12, respectively.

[0020] 2 and 3, the support frame 20 has a frame shape with an opening 22. The MEA 14 is disposed in the opening 22 of the support frame 20. The support frame 20 surrounds the periphery of the MEA 14. Although not particularly limited, the support frame 20 is made of a thermosetting resin such as an epoxy resin or a phenolic resin. The support frame 20 is also provided with six manifold holes 28a-28f, similar to the separators 16 and 18 described above.

[0021] One surface 20a of the support frame 20 faces the anode side separator 16 and is bonded to the anode side separator 16 via a first adhesive layer 24. The first adhesive layer 24 is made of a pressure-sensitive adhesive (PSA). The first adhesive layer 24 is provided along a predetermined seal line on the one surface 20a of the support frame 20. The seal line of the first adhesive layer 24 is determined so as to surround the opening 22 of the support frame 20 and each of the manifold holes 28a-28f. The other surface 20b of the support frame 20 faces the cathode side separator 18 and is bonded to the cathode side separator 18 via a second adhesive layer 26 (see FIGS. 4(A)-(C)). The second adhesive layer 26 is also made of a pressure-sensitive adhesive (PSA). The second adhesive layer 26 is provided along a predetermined seal line on the other surface 20b of the support frame 20. The seal line of the second adhesive layer 26 is also defined so as to surround the opening 22 of the support frame 20 and each of the manifold holes 28a-28f.

[0022] A method for manufacturing the fuel cell 10 will be described with reference to Figs. 3 and 4. As shown in Figs. 3 and 4(A), the manufacturing method includes a step of forming adhesive layers 24, 26 on the respective surfaces 20a, 20b of the support frame 20 that supports the MEA 14. In this step, a pressure-sensitive adhesive is applied to the respective surfaces 20a, 20b of the support frame 20 along a predetermined seal line. As a result, the adhesive layers 24, 26 are formed on the respective surfaces 20a, 20b of the support frame 20. There is no particular limitation on the specific method for applying the adhesive. As an example, the adhesive can be applied by inkjet printing, screen printing, or the like.

[0023] As shown in FIG. 4(A), in the process of forming the adhesive layers 24, 26, the adhesive is applied so that the surfaces of the adhesive layers 24, 26 are convex in a cross section perpendicular to the longitudinal direction of the seal line. As a result, for example, the thickness of the first adhesive layer 24 is maximum at the first point P1, and decreases monotonically as it moves away from the first point P1 in the width direction (i.e., X direction) of the seal line. The monotonous decrease here means a continuous or intermittent decrease, and does not increase. The position of the first point P1 at which the thickness of the first adhesive layer 24 is maximum is not particularly limited. As an example, in the first adhesive layer 24 of this embodiment, in a cross section perpendicular to the longitudinal direction of the seal line, the first point P1 is located at the center in the width direction (i.e., X direction), and the first adhesive layer 24 has a bilaterally symmetrical shape. Similarly, the thickness of the second adhesive layer 26 is maximum at the second point P2 and monotonically decreases with increasing distance from the second point P2 in the width direction of the seal line (i.e., the X direction). Here, in a cross section perpendicular to the longitudinal direction of the seal line, the shape of the second adhesive layer 26 may be vertically symmetrical or asymmetrical to the shape of the first adhesive layer 24.

[0024] 4(B), the manufacturing method includes a step of bringing the separators 16, 18 close to the respective surfaces 20a, 20b of the support frame 20. In this step, the separators 16, 18 are brought close to the respective surfaces 20a, 20b of the support frame 20 until they come into contact with the adhesive layers 24, 26 on the support frame 20. As a result, the anode side separator 16 comes into contact with the first adhesive layer 24 on one surface 20a of the support frame 20 and is positioned. The cathode side separator 18 comes into contact with the second adhesive layer 26 formed on the other surface 20b of the support frame 20 and is positioned.

[0025] As described above, the surfaces of the adhesive layers 24 and 26 each have a convex shape. Therefore, when the anode-side separator 16 approaches the first adhesive layer 24, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the first adhesive layer 24 and the surface of the anode-side separator 16 facing that surface is minimized at a first point P1 and increases monotonically as it moves away from the first point P1 in the width direction of the seal line (i.e., the X direction). The monotonically increasing here means a continuous or intermittent increase, not a decrease. Similarly, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the second adhesive layer 26 and the surface of the cathode-side separator 18 facing that surface is minimized at a second point P2 and increases monotonically as it moves away from the second point P2 in the width direction of the seal line (i.e., the X direction).

[0026] According to the above configuration, the surfaces of the adhesive layers 24, 26 first start contacting the surfaces of the separators 16, 18 at the first point P1 and the second point P2. After that, the surfaces of the adhesive layers 24, 26 gradually contact the separators 16, 18 toward both sides of the width direction (i.e., the X direction) of the seal line. Therefore, it is possible to suppress the trapping of air bubbles between the adhesive layers 24, 26 and the separators 16, 18. Even if air bubbles are trapped between the adhesive layers 24, 26 and the separators 16, 18, the air bubbles can be pushed outward from a specific point (i.e., the first point P1, the second point P2) toward both sides of the width direction of the seal line. This suppresses the formation of air bubbles in the adhesive layers 24, 26 formed of a pressure-sensitive adhesive.

[0027] Thereafter, as shown in Fig. 4(C), the manufacturing method includes a step of bonding the support frame 20 and the separators 16, 18 to each other. In this step, a compressive force is applied to the support frame 20 and the separators 16, 18, which are in contact with each other via the adhesive layers 24, 26. As a result, the anode side separator 16 is bonded to the support frame 20 via the first adhesive layer 24, and the cathode side separator 18 is bonded to the support frame 20 via the second adhesive layer 26. Note that there are no particular limitations on the method of bringing the separators 16, 18 close to the support frame 20 and the method of applying a compressive force to the support frame 20 and the separators 16, 18. As an example, a press machine or the like can be used in these steps.

[0028] 5(A)-(C) show some modified examples of the adhesive layers 24, 26. As shown in FIG. 5(A), in a cross section perpendicular to the longitudinal direction of the seal line, the adhesive layers 24, 26 formed on the support frame 20 may have a shape in which a part or all of the surface is curved concavely. Alternatively, as shown in FIG. 5(B) and (C), in a cross section perpendicular to the longitudinal direction of the seal line, the adhesive layers 24, 26 formed on the support frame 20 may have a shape in which the thickness is maximum at the end in the width direction. In this case, the two adhesive layers 24, 26 may have vertically asymmetric shapes (see FIG. 5(B)) or vertically symmetric shapes (see FIG. 5(C)).

[0029] As described above, the adhesive layers 24, 26 are formed to surround the opening 22 of the support frame 20 and each of the manifold holes 28a-28f. In this case, the adhesive layers 24, 26 have sections adjacent to the manifold holes 28a-28f and sections not adjacent to the manifold holes 28a-28f. The pressure acting on the adhesive layers 24, 26 is relatively high in the vicinity of the manifold holes 28a-28f. For this reason, the width and / or thickness of the first adhesive layer 24 may be made larger in the sections adjacent to the manifold holes 28a-28f than in the sections not adjacent to the manifold holes 28a-28f.

[0030] In the above-described embodiment and modified example, each of the two adhesive layers 24, 26 has a shape whose thickness varies in the width direction. In contrast, in other embodiments, only one of the two adhesive layers 24, 26 may have a shape whose thickness varies in the width direction. That is, the other of the two adhesive layers 24, 26 may have a shape whose thickness is constant in the width direction.

[0031] In the above-described embodiment and modified example, each of the two adhesive layers 24, 26 has a shape in which the thickness varies in the width direction. In contrast, in another embodiment, as shown in Figures 6(A) and 6(B), the above-described profile provided on the surface of the adhesive layers 24, 26 may be provided on the surface of the separators 16, 18 that contact the adhesive layers 24, 26. That is, the surfaces of the separators 16, 18 may be provided with protrusions 32 that protrude toward the adhesive layers 24, 26. In this case, it is preferable that the protrusion amount of the protrusion 32 is maximum at a specific point Q1, Q2, and monotonically decreases with increasing distance from the point Q1, Q2 in the width direction of the seal line (ie, the X direction).

[0032] Even with this configuration, when the anode side separator 16 approaches the first adhesive layer 24, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the first adhesive layer 24 and the surface of the anode side separator 16 facing that surface is minimum at the point Q1 and increases monotonically with increasing distance from the point Q1 in the width direction of the seal line (i.e., the X direction). This prevents air bubbles from being formed in the adhesive layers 24, 26.

[0033] In this embodiment, the support frame 20 and the separators 16, 18 are bonded to each other via adhesive layers 24, 26 formed of a pressure-sensitive adhesive. Alternatively or in addition to this, the anode side separator 16 of one fuel cell 12 and the cathode side separator 18 of another adjacent fuel cell 12 may be bonded to each other via adhesive layers 24, 26 formed of a pressure-sensitive adhesive.

[0034] In this case, as shown in Fig. 7(A), the manufacturing method includes a step of forming a third adhesive layer 34 on the surface of the anode side separator 16. In this step, a pressure-sensitive adhesive is applied along a seal line defined in the anode side separator 16. The third adhesive layer 34 may have a shape whose thickness varies in the width direction, similar to the above-mentioned adhesive layers 24, 26 (see Figs. 4 and 5).

[0035] Next, as shown in Fig. 7(B), the manufacturing method includes a step of bringing the cathode side separator 18 of another fuel cell 12 close to the surface of the anode side separator 16. In this step, the cathode side separator 18 is brought close to the anode side separator 16 until it comes into contact with the third adhesive layer 34 on the anode side separator 16. As a result, the cathode side separator 18 comes into contact with the third adhesive layer 34 on the anode side separator 16 and is positioned. This step may be performed simultaneously with the step of Fig. 4(B) described above.

[0036] The third adhesive layer 34 has a shape in which the thickness changes in the width direction (i.e., the X direction) of the seal line. Therefore, when the cathode-side separator 18 approaches the third adhesive layer 34, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the third adhesive layer 34 and the surface of the cathode-side separator 18 facing that surface is minimum at a specific point R1, and increases monotonically with distance from the point R1 in the width direction of the seal line. This prevents air bubbles from being formed even in the third adhesive layer 34 formed of a pressure-sensitive adhesive.

[0037] Next, as shown in Fig. 7(C), the manufacturing method includes a step of bonding the two separators 16, 18 to each other. In this step, a compressive force is applied to the two separators 16, 18 that are in contact with each other via the third adhesive layer 34. This causes the two separators 16, 18 to be bonded to each other via the third adhesive layer 34. As a result, the two separators 16, 18 are sealed by the third adhesive layer 34, and a gasket that would otherwise be required between the two separators 16, 18 can be omitted. This step may be performed simultaneously with the step of Fig. 4(C) described above.

[0038] The anode-side separator 16 in this embodiment is an example of the first separator in the present technology, and the cathode-side separator 18 in this embodiment is an example of the second separator in the present technology. As a modified example, the third adhesive layer 34 may be formed on the cathode-side separator 18 instead of the anode-side separator 16.

[0039] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical usefulness alone or in combination. [Explanation of symbols]

[0040] 10: fuel cell, 12: fuel cell cell, 14: MEA, 16, 18: separator, 20: support frame, 20a, 20b: surface, 22: opening, 24, 26: adhesive layer, 28a-28f: manifold holes, 32: protrusion, 34: adhesive layer

Claims

**Claim 1** A method for manufacturing a fuel cell, comprising: a step of applying a pressure-sensitive adhesive along a predetermined seal line on the surface of a support frame that supports a membrane electrode assembly to form an adhesive layer; a step of approaching a separator to the surface of the support frame until it contacts the adhesive layer formed on the support frame; a step of applying a compressive force to the support frame and the separator that are in contact via the adhesive layer to bond the support frame and the separator to each other; wherein in the approaching step, in a cross-section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the adhesive layer and the surface of the separator facing the surface of the adhesive layer is minimized at a specific location, and monotonically increases as the distance from the specific location in the width direction of the seal line increases; a manufacturing method. **Claim 2** The method for manufacturing a fuel cell according to claim 1, wherein in the step of forming the adhesive layer, the adhesive is applied such that in the cross-section perpendicular to the longitudinal direction of the seal line, the thickness of the adhesive layer is maximized at the specific location and monotonically decreases as the distance from the specific location in the width direction of the seal line increases. **Claim 3** The method for manufacturing a fuel cell according to claim 2, wherein in the step of forming the adhesive layer, the adhesive is applied such that in the cross-section perpendicular to the longitudinal direction of the seal line, the adhesive layer has a bilaterally symmetric shape. **Claim 4** The method for manufacturing a fuel cell according to any one of claims 1 to 3, wherein in the approaching step, in the cross-section perpendicular to the longitudinal direction of the seal line, the surface of the separator facing the adhesive layer protrudes toward the adhesive layer, and the amount of protrusion is maximized at the specific location and monotonically decreases as the distance from the specific location in the width direction of the seal line increases. **Claim 5** A method for manufacturing a fuel cell, comprising: a step of applying a pressure-sensitive adhesive along a predetermined seal line on the surface of a first separator that constitutes a fuel cell stack to form an adhesive layer; a step of approaching a second separator that constitutes another fuel cell stack to the surface of the first separator until it contacts the adhesive layer formed on the first separator; a step of applying a compressive force to the first separator and the second separator that are in contact via the adhesive layer to bond the first separator and the second separator to each other; wherein In the step of bringing them closer, in a cross section perpendicular to the longitudinal direction of the seal line, the distance between the surface of the adhesive layer and the surface of the second separator facing the surface is minimized at a specific location, and monotonically increases as the distance from the specific location in the width direction of the seal line increases. Method for manufacturing a fuel cell.

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