fuel cell stack

Abstract

To provide a fuel cell stack in which side flow of cooling medium can be suppressed.SOLUTION: A fuel cell stack is formed by laminating a plurality of single cells 90 each comprising an MEA (Membrane Electrode Assembly), a first separator 30, and a second separator 40. The first separator 30 has first protruding portions 50 abutting on the second separator 40 of the other single cell 90 adjacent to the concerned single cell 90. A plurality of first protruding portions 50 are provided outside an outside groove flow channel and arranged in a second direction Y. The second separator 40 has a plurality of second protruding portions 60 abutting on the first protruding portions 50. A recessed portion 52 extending in a third direction is provided at a center portion of a distal end portion 51 of each first protruding portion 50. A distal end portion 61 of each second protruding portion 60 has a projecting portion 62 located in the recessed portion 52 and protruded toward a bottom face 52a of the recessed portion 52.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fuel cell stack. [Background technology]

[0002] Patent Document 1 discloses a fuel cell stack. This fuel cell stack includes a plurality of stacked unit cells. Each unit cell includes two separators. Between the two separators, a membrane electrode assembly and two gas diffusion layers are provided, sandwiching the membrane electrode assembly in the stacking direction of the unit cells.

[0003] A groove-like flow path for guiding a reaction medium is provided on the surface of each separator facing the gas diffusion layer, and a groove-like flow path for forming a cavity for guiding a cooling medium between the separators of adjacent single cells is provided on the surface opposite to the facing surface of each separator.

[0004] Furthermore, the opposing surfaces of the separators are provided with convex beads and recesses formed between the beads and the flow paths. The beads are provided all around the periphery of the flow path.

[0005] The bottom walls of the recesses formed in each separator are in contact with each other (see FIG. 6A of Patent Document 1). In a fuel cell stack including such a separator, the cooling medium flowing through the cavity is prevented from flowing toward the beads, that is, from flowing by the recesses that are in contact with each other.

[0006] Patent Document 2 also discloses a molding method for forming a separator for a fuel cell from a metal sheet. In this molding method, a continuous protrusion, i.e., a separator flow path, is formed in the metal sheet between the recess and protrusion of a fixed die and the protrusion and recess of a movable punch. The recesses of the die and punch have bottoms that are convexly curved in the center. Therefore, the center of the formed protrusion is curved concavely. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2020-522089 [Patent Document 2] Japanese Patent Application Publication No. 2018-89679 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when the molding method described in Patent Document 2, for example, is used to mold the separator for the fuel cell described in Patent Document 1, the following problem occurs. Specifically, the central portions of the opposing surfaces of the bottom walls of the recesses are curved in a concave shape. As a result, gaps are formed between the bottom walls of the recesses of each separator. As a result, the cooling medium that has flowed sideways from the cavity leaks out through the gaps, reducing the effect of the recesses in suppressing sideways flow. This may result in a decrease in the cooling efficiency of the cooling medium and, ultimately, a decrease in the power generation efficiency of the fuel cell.

[0009] It should be noted that this problem is not limited to the application of the molding method described in Patent Document 2. For example, the same problem can occur if the bottom wall of the recess has a depression due to molding shrinkage or the like.

[0010] An object of the present invention is to provide a fuel cell stack that can suppress side flow of a cooling medium. [Means for solving the problem]

[0011] A fuel cell stack for achieving the above object is formed by stacking a plurality of unit cells in a first direction, each unit cell including a power generation section and a first separator and a second separator sandwiching the power generation section, and a plurality of groove channels extending in a second direction and through which a cooling medium flows are arranged on a surface of each of the first separator and the second separator opposite to a surface facing the power generation section, and the first separator projects toward the second separator of another unit cell adjacent to the first unit cell in the first direction and abuts against the second separator. The second separator has a first convex portion, the first convex portion being provided outside the groove flow path that is located outermost in a third direction that intersects both the first direction and the second direction, and a plurality of second convex portions being provided side by side in the second direction, the second separator having a plurality of second convex portions that each protrude toward the first convex portion in the first direction and abut against the first convex portion, a recessed portion extending in the third direction is provided at the center in the second direction of the tip of the first convex portion, and the tip of the second convex portion is located within the recessed portion and has a protruding portion that protrudes toward the bottom surface of the recessed portion.

[0012] According to this configuration, the first and second protrusions abut with the tip of the second protrusion positioned within the recess of the first protrusion. Here, the protruding portion of the tip of the second protrusion protrudes toward the bottom surface of the recess. Therefore, a gap is less likely to form between the recess of the first protrusion and the second protrusion, compared to when a recess is provided at the tip of the second protrusion or when the tip of the second protrusion is flat. This makes it less likely for the coolant to flow outside the first and second protrusions through the gap. Therefore, sideways flow of the coolant can be suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an exploded perspective view showing a unit cell of an embodiment of a fuel cell stack. [Figure 2] FIG. 2 is a cross-sectional view showing the fuel cell stack of the same embodiment. [Figure 3]FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a modified example of the fuel cell stack, corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of a fuel cell stack will now be described with reference to Figures 1 to 3. Note that in each drawing, some components are shown exaggerated or simplified for ease of explanation, and the dimensional proportions of each component may differ from the actual proportions. Furthermore, "orthogonal" in the following description does not necessarily mean a strict perpendicular intersection, but also includes a roughly perpendicular intersection within the scope of the effects of each embodiment.

[0015] <Fuel cell stack unit cell 90> As shown in FIGS. 1 and 2, the fuel cell stack is formed by stacking a plurality of unit cells 90, each of which has a rectangular plate shape as a whole.

[0016] In the following description, the stacking direction of the unit cells 90 will be referred to as a first direction X. Furthermore, among the directions perpendicular to the first direction X, the longitudinal direction of the unit cells 90 will be referred to as a second direction Y. Furthermore, the direction perpendicular to both the first direction X and the second direction Y will be referred to as a third direction Z.

[0017] The unit cell 90 has inlet-side manifolds 91, 93, and 95 for introducing a reactant gas or a cooling medium into the unit cell 90, and outlet-side manifolds 92, 94, and 96 for discharging the reactant gas and cooling medium from the unit cell 90 to the outside. In this embodiment, the inlet-side manifold 91 and the outlet-side manifold 92 are manifolds through which a fuel gas flows. The fuel gas is, for example, hydrogen gas. The inlet-side manifold 93 and the outlet-side manifold 94 are manifolds through which a cooling medium flows. The cooling medium is, for example, cooling water. The inlet-side manifold 95 and the outlet-side manifold 96 are manifolds through which an oxidizer gas flows. The oxidizer gas is, for example, air.

[0018] The inlet side manifolds 91, 93, 95 and the outlet side manifolds 92, 94, 96 are rectangular in plan view and penetrate the unit cell 90 in the first direction X. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are provided at the end of one side (the left side in the left-right direction in FIG. 1) of the unit cell 90 in the second direction Y. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are lined up in order from one side (the far side of the paper in FIG. 1) to the other side (the near side of the paper in FIG. 1) in the third direction Z.

[0019] The outlet-side manifold 92 and the inlet-side manifolds 93 and 95 are provided at the end of the unit cell 90 on the other side (the right side in FIG. 1) in the second direction Y. The outlet-side manifold 92 and the inlet-side manifolds 93 and 95 are lined up in order from the other side (the front side of the paper in FIG. 1) to one side (the back side of the paper in FIG. 1) in the third direction Z.

[0020] The unit cell 90 has a membrane electrode assembly (hereinafter referred to as MEA 10), a frame member 20 that holds the MEA 10, and a first separator 30 and a second separator 40 that sandwich the MEA 10 and the frame member 20.

[0021] Each component will be described in detail below. <mea10> 1, the MEA 10 has a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane) (not shown) and electrodes 11 and 12 provided on both sides of the electrolyte membrane. In this embodiment, the electrode bonded to one side of the electrolyte membrane in the first direction X (the upper side in the vertical direction in FIG. 1) is the cathode electrode 11. The electrode bonded to the other side of the electrolyte membrane in the first direction X (the lower side in FIG. 1) is the anode electrode 12.

[0022] Each of the electrodes 11 and 12 has a catalyst layer bonded to the electrolyte membrane and a gas diffusion layer bonded to the catalyst layer (both not shown). The MEA 10 corresponds to the power generating section of the fuel cell according to the present invention.

[0023] <Frame member 20> As shown in FIGS. 1 and 2, the frame member 20 has a rectangular frame shape that is long in the second direction Y, and is made of, for example, a synthetic resin material.

[0024] The frame member 20 has through holes 21, 22, 23, 24, 25, and 26 that form the manifolds 91, 92, 93, 94, 95, and 96, respectively. The frame member 20 has an opening 27 in the center. The MEA 10 is joined to the periphery of the opening 27 from one side in the first direction X (the upper side in FIG. 1).

[0025] <First separator 30> As shown in FIGS. 1 and 2, the first separator 30 is formed by press-forming a metal plate made of, for example, titanium or stainless steel and having a rectangular shape in plan view.

[0026] The first separator 30 has through holes 31, 32, 33, 34, 35, and 36 that form the manifolds 91, 92, 93, 94, 95, and 96, respectively. The first separator 30 has a first surface 30A having a facing surface 30a that faces the anode electrode 12 of the MEA 10 in the first direction X, and a second surface 30B having a surface 30b opposite to the facing surface 30a.

[0027] The first surface 30A is provided with a plurality of grooves 37A through which the fuel gas flows and a pair of connecting portions 37B. Note that the grooves 37A and the connecting portions 37B are shown in simplified form in FIG.

[0028] A plurality of grooves 37A are provided on the opposing surface 30a. Each of the plurality of grooves 37A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 37A is arranged at intervals in the third direction Z (see FIG. 2).

[0029] 1, the pair of connecting portions 37B extend from both sides of the plurality of groove flow paths 37A in the second direction Y toward the through holes 31, 32. Fuel gas is introduced from the inlet-side manifold 91 into the plurality of groove flow paths 37A via one connecting portion 37B. The fuel gas flowing through the plurality of groove flow paths 37A is discharged to the outlet-side manifold 92 via the other connecting portion 37B.

[0030] 1 and 2, the second surface 30B is provided with a plurality of groove channels 38A through which a cooling medium flows, a pair of connecting portions 38B, and a first protrusion 50. Note that in FIG. 1, the groove channels 38A and the connecting portions 38B are illustrated in a simplified manner.

[0031] A plurality of grooves 38A are provided on the surface 30b. Each of the plurality of grooves 38A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 38A is arranged at intervals in the third direction Z (see FIG. 2).

[0032] 2, grooves 37A are formed by the back sides of the convex portions located between adjacent grooves 38A in the third direction Z. Also, grooves 38A are formed by the back sides of the convex portions located between adjacent grooves 37A in the third direction Z.

[0033] 1 extend from both sides of the groove flow paths 38A toward the through holes 33, 34 in the second direction Y. The coolant is introduced from the inlet manifold 93 into the groove flow paths 38A via one of the connecting portions 38B. The coolant flowing through the groove flow paths 38A is discharged to the outlet manifold 94 via the other connecting portion 38B.

[0034] <First protrusion 50> 1 and 2, the first protrusions 50 are provided on the outside of a pair of outer grooves 38a that are located outermost in the third direction Z among the plurality of grooves 38A. In this embodiment, the first protrusions 50 are provided on the outside of both of the pair of outer grooves 38a (see FIG. 1). Here, "outside" in the third direction Z refers to the side that is away from the center of the unit cell 90 in the third direction Z. Note that FIG. 2 illustrates the outer grooves 38a that are located on one side of the pair of outer grooves 38a in the third direction Z (the far side of the paper in FIG. 1), and the first protrusions 50 that are located on the outside of the outer grooves 38a.

[0035] The first protrusion 50 protrudes toward the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X (see FIG. 2). The first protrusion 50 extends in the third direction Z.

[0036] 1, the first protrusions 50 are arranged at intervals in the second direction Y. The first protrusions 50 are provided over the entire range in the second direction Y where the outer groove flow passage 38a is formed.

[0037] As shown in FIG. 3, a recess 52 is provided at the tip 51 of each first protrusion 50. The recess 52 is located in the center of the tip 51 in the second direction Y. As shown in FIG. 2, the recessed portion 52 extends in the third direction Z.

[0038] As shown in FIG. 3, the recessed portion 52 is curved with respect to an imaginary line (not shown) extending in the second direction Y in a cross-sectional view. In this embodiment, the height H1 of the first protrusion 50 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less.

[0039] In this embodiment, the width W of the tip portion 51 in the second direction Y is set within a range of 0.5 mm or more and 2 mm or less. In this embodiment, the depth D of the recess 52 in the first direction X is set within a range of 10 μm or more and 50 μm or less.

[0040] <Second separator 40> As shown in FIGS. 1 and 2, the second separator 40 is formed by press-forming a metal plate made of, for example, titanium or stainless steel and having a rectangular shape in plan view.

[0041] The second separator 40 has through holes 41, 42, 43, 44, 45, and 46 that form the manifolds 91, 92, 93, 94, 95, and 96, respectively. The second separator 40 has a first surface 40A having a facing surface 40a that faces the cathode electrode 11 of the MEA 10 in the first direction X, and a second surface 40B having a surface 40b opposite to the facing surface 40a.

[0042] The first surface 40A is provided with a plurality of grooves 47A through which the oxidant gas flows and a pair of connection portions 47B. Note that the grooves 47A and the connection portions 47B are shown in simplified form in FIG.

[0043] A plurality of grooves 47A are provided on the opposing surface 40a. Each of the plurality of grooves 47A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 47A is arranged at intervals in the third direction Z (see FIG. 2).

[0044] 1 extend from both sides of the groove flow paths 47A toward the through holes 45, 46 in the second direction Y. The oxidant gas is introduced into the groove flow paths 47A from the inlet manifold 95 via one of the connecting portions 47B. The oxidant gas flowing through the groove flow paths 47A is discharged to the outlet manifold 96 via the other connecting portion 47B.

[0045] 1 and 2, the second surface 40B is provided with a plurality of groove channels 48A through which the coolant flows, a pair of connecting portions 48B, and a second protrusion 60. Note that in FIG. 1, the groove channels 48A and the connecting portions 48B are illustrated in a simplified manner.

[0046] The plurality of grooves 48A are provided on the surface 40b. Each of the plurality of grooves 48A extends linearly in the second direction Y (see FIG. 1). Each of the plurality of grooves 48A is arranged at intervals in the third direction Z (see FIG. 2).

[0047] 2, grooves 47A are formed by the back sides of the convex portions located between adjacent grooves 48A in the third direction Z. Also, grooves 48A are formed by the back sides of the convex portions located between adjacent grooves 47A in the third direction Z.

[0048] 1, the pair of connecting portions 48B extend from both sides of the plurality of groove flow paths 48A in the second direction Y toward the through holes 43, 44. The coolant is introduced into the plurality of groove flow paths 48A from the inlet-side manifold 93 via one connecting portion 48B. The coolant flowing through the plurality of groove flow paths 48A is discharged to the outlet-side manifold 94 via the other connecting portion 48B.

[0049] <Second protrusion 60> 1 and 2, the second convex portions 60 are provided on the outside of a pair of outer groove channels 48a that are located outermost in the third direction Z among the plurality of groove channels 48A. In this embodiment, the second convex portions 60 are provided on the outside of both of the pair of outer groove channels 48a (see FIG. 1). Note that FIG. 2 illustrates the outer groove channel 48a that is located on one side of the pair of outer groove channels 48a in the third direction Z, and the second convex portions 60 that are located on the outside of the outer groove channel 48a.

[0050] The second protrusion 60 protrudes toward the first protrusion 50 in the first direction X (see FIG. 2). The second protrusion 60 extends in the third direction Z.

[0051] 1, the second protrusions 60 are arranged at intervals in the second direction Y. The second protrusions 60 are provided over the entire area in the second direction Y where the outer groove flow passage 48a is formed. In this embodiment, one second protrusion 60 is provided at a position corresponding to each of the first protrusions 50 in the first direction X.

[0052] As shown in FIG. 3, the tip 61 of the second protrusion 60 is curved along the recess 52 in a cross-sectional view. The tip portion 61 has a protruding portion 62 that protrudes toward the bottom surface 52a of the recessed portion 52. In this embodiment, the portion of the tip portion 61 that is located within the recessed portion 52 and abuts against the recessed portion 52 is the protruding portion 62. In other words, the protruding portion 62 is curved along the recessed portion 52 in a cross-sectional view. The protruding portion 62 fits snugly into the recessed portion 52.

[0053] As shown in FIG. 2, the protrusion 62 extends in the third direction Z. As shown in FIG. 3, the height H2 of the second protrusion 60 in the first direction X is set within a range of 0.2 mm or more and 0.8 mm or less in this embodiment.

[0054] 2, a gasket 70 is provided outside the first protrusions 50 and the second protrusions 60 in the third direction Z to seal between the separator 30 of the unit cell 90 and the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X. The multiple first protrusions 50 and the multiple second protrusions 60 are configured to partially fill the space S formed between the gasket 70 and the outer groove flow paths 38a, 48a in the third direction Z.

[0055] Next, the operation of this embodiment will be described. The first protrusion 50 and the second protrusion 60 come into contact with each other with the tip 61 of the second protrusion 60 positioned within the recess 52 of the first protrusion 50. Here, the protrusion 62 of the tip 61 of the second protrusion 60 protrudes toward the bottom surface 52a of the recess 52. Therefore, a gap is less likely to be formed between the recess 52 of the first protrusion 50 and the second protrusion 60 compared to when a recess is provided in the tip 61 of the second protrusion 60 or when the tip 61 of the second protrusion 60 is flat. This makes it less likely for the coolant to flow to the outside of the first protrusion 50 and the second protrusion 60 through the gap.

[0056] Next, the effects of this embodiment will be described. (1) The first separator 30 has a first protrusion 50 that protrudes toward the second separator 40 of another unit cell 90 adjacent to the unit cell 90 in the first direction X and abuts against the second separator 40. The first protrusion 50 is provided outside the outer groove flow passage 38a that is located outermost in the third direction Z. A plurality of first protrusions 50 are provided side by side in the second direction Y. The second separator 40 has a plurality of second protrusions 60 that protrude toward the first protrusions 50 in the first direction X and abut against the first protrusions 50. A recess 52 extending in the third direction Z is provided at the center in the second direction Y of the tip 51 of each first protrusion 50. The tip 61 of the second protrusion 60 is located within the recess 52 and has a protrusion 62 that protrudes toward the bottom surface 52a of the recess 52.

[0057] This configuration provides the above-mentioned effects, and therefore, the side flow of the cooling medium can be suppressed. (2) The recessed portion 52 is curved with respect to an imaginary line extending in the second direction Y. The protruding portion 62 is curved along the recessed portion 52 and abuts against the recessed portion 52.

[0058] With this configuration, almost no gap is formed between the recessed portion 52 of the first protrusion 50 and the second protrusion 60. Therefore, sideways flow of the cooling medium can be further suppressed. (3) The multiple first protrusions 50 are provided over the entire area in which the outer groove flow passage 38a is formed in the second direction Y. The multiple second protrusions 60 are provided over the entire area in which the outer groove flow passage 48a is formed in the second direction Y.

[0059] With this configuration, the above-described effect is exerted over the entire range in which the outer groove passages 38a, 48a are formed in the second direction Y. Therefore, sideways flow of the cooling medium can be further suppressed.

[0060] (4) The first separator 30 and the second separator 40 are made of metal plates. When the separator 30 is made of a metal plate, recesses 52 are likely to be formed at the tip ends 51 of the first protrusions 50 during molding. When the separator 40 is made of a metal plate, recesses are likely to be formed at the tip ends 61 of the second protrusions 60 during molding.

[0061] In this regard, the above-described configuration can suppress sideways flow of the cooling medium caused by the recessed portion. <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0062] The shapes of the inlet side manifolds 91, 93, 95 and the outlet side manifolds 92, 94, 96 are not limited to the rectangular shape in plan view as exemplified in this embodiment, but may be, for example, an elliptical shape in plan view.

[0063] The flows of the reactant gas and the coolant in the manifolds 91, 92, 93, 94, 95, and 96 are not limited to those exemplified in this embodiment. For example, the manifold 96 may be an inlet manifold for the oxidant gas, and the manifold 95 may be an outlet manifold for the oxidant gas. Accordingly, the manifold 94 may be an inlet manifold for the coolant, and the manifold 93 may be an outlet manifold for the coolant. That is, the oxidant gas flowing through the groove flow passages 47A and the coolant flowing through the groove flow passages 38A and 48A may flow in the same direction as the fuel gas flowing through the groove flow passage 37A.

[0064] The groove flow channels 37A (38A) are not limited to those extending linearly in the second direction Y as illustrated in this embodiment. For example, the groove flow channels 37A (38A) may extend in a wavy manner in the planar direction of the opposing surface 30a (surface 30b).

[0065] The groove flow channels 47A (48A) are not limited to those extending linearly in the second direction Y as illustrated in this embodiment. For example, the groove flow channels 47A (48A) may extend in a wavy manner in the planar direction of the opposing surface 40a (surface 40b).

[0066] The shape of the first protrusion 50 is not limited to the shape exemplified in this embodiment. For example, the height H1 of the first protrusion 50 may be smaller than 0.2 mm or larger than 0.8 mm. In this case, the height H2 of the second protrusion 60 is not limited to the range of 0.2 mm to 0.8 mm, but may be appropriately changed to match the height H1 of the first protrusion 50. Furthermore, the width W of the first protrusion 50 is not limited to the range of 0.5 mm to 2 mm, but may be smaller than 0.5 mm or larger than 2 mm, as long as it is within the range in which the effects of the present invention are achieved.

[0067] The first separator 30 and the second separator 40 are not limited to those in which the recessed portion 52 of the first protrusion 50 and the protruding portion 62 of the second protrusion 60 fit together without any gap, as exemplified in this embodiment. For example, as shown in Fig. 4, the separator 30 and the separator 40 may have a first protrusion 150 and a second protrusion 160 having a recessed portion 152 and a protruding portion 162 that form a gap G between them. In this case, it is sufficient that the protruding portion 162 is positioned within the recessed portion 152 and abuts against the recessed portion 152.

[0068] The second protrusion 60 is not limited to the one in which the tip 61 is curved along the recess 52 in a cross-sectional view, as exemplified in this embodiment. For example, the tip 61 of the second protrusion 60 may have a flat portion extending in the planar direction of the second surface 40B and a protruding portion protruding from the flat portion toward the bottom surface 52a of the recess 52.

[0069] The recessed portion 52 is not limited to being curved with respect to a virtual straight line extending in the second direction Y in a cross-sectional view, as illustrated in this embodiment. For example, the recessed portion 52 may have a flat bottom surface extending in the planar direction of the second surface 30B.

[0070] The first protrusions 50 are not limited to being provided on the outside of both of the pair of outer groove channels 38a as illustrated in this embodiment. The first protrusions 50 may be provided on the outside of only one of the pair of outer groove channels 38a. In this case, the second protrusions 60 are not limited to being provided on the outside of both of the pair of outer groove channels 48a, and their arrangement may be changed appropriately to match the first protrusions 50.

[0071] The fuel cell stack is not limited to the configuration illustrated in this embodiment in which one second protrusion 60 is provided at a position corresponding to each of the multiple first protrusions 50 in the first direction X, and some of the second protrusions 60 may be omitted. In this case, the separator 30 includes first protrusions 50 that do not face the second protrusions 60 in the first direction X. Note that the first protrusions 50 that do not face the second protrusions 60 may be in contact with the second surface 40B of the separator 40.

[0072] The separators 30, 40 are not limited to those formed by press-forming a metal plate material, but can also be formed by, for example, cutting or etching. The material of the separators 30, 40 is not limited to titanium or stainless steel, but aluminum or carbon can also be used.

[0073] The first separator according to the present invention is not limited to being an anode-side separator as exemplified in this embodiment, but can also be used as a cathode-side separator, in which case the second separator according to the present invention should be used as the anode-side separator. [Explanation of symbols]

[0074] D...Depth G...gap H1, H2...height S…Space W…width X…first direction Y...Second direction Z...Third direction 10...MEA 11...Anode electrode 12...Cathode electrode 20...Frame member 21...Through hole 22...Through hole 23...Through hole 24...Through hole 25...Through hole 26...Through hole 27...Opening 30...First separator 30A…First side 30a...Opposing surface 30B…Second side 30b…side 31...Through hole 32...Through hole 33...Through hole 34...Through hole 35...Through hole 36...Through hole 37A…Groove channel 37B...Connection 38A…Groove channel 38a...Outer groove channel 38B...Connection 40...Second separator 40A...Page 1 40a...opposing surface 40B…Second side 40b...side 41...Through hole 42...Through hole 43...Through hole 44...Through hole 45...Through hole 46...Through hole 47A…Groove channel 47B...Connection 48A…Groove channel 48a...Outer groove channel 48B...Connection 50,150...First convex part 51...Tip 52,152...recess 52a...bottom 60,160...Second convex part 61...Tip 62,162...Protrusion 70...Gasket 90...single cell 91...Inlet manifold 92...Outlet manifold 93...Inlet manifold 94...Outlet manifold 95...Inlet manifold 96...Outlet manifold

Claims

1. A fuel cell stack is formed by stacking a plurality of unit cells in a first direction, each unit cell including a power generation section and a first separator and a second separator sandwiching the power generation section, and each of the first separator and the second separator has a surface opposite to a surface facing the power generation section, the surface of each of the first separator and the second separator having a plurality of groove channels extending in a second direction and through which a coolant flows, the first separator has a first protrusion that protrudes toward the second separator of another unit cell adjacent to the unit cell in the first direction and abuts against the second separator, the first convex portion is provided outside the groove flow path that is located outermost in a third direction that intersects both the first direction and the second direction, and a plurality of the first convex portions are provided side by side in the second direction, the second separator has a plurality of second protrusions that protrude toward the first protrusions in the first direction and abut against the first protrusions, a tip end of the first convex portion is provided with a recessed portion located in a center portion in the second direction and extending in the third direction, and a pair of first protrusions located on both sides of the recessed portion in the second direction, the recessed portion is curved with respect to a virtual line extending in the second direction, a tip end surface of each of the pair of first protrusions is curved with respect to a virtual straight line extending in the second direction and is a curved surface that is continuous with a side surface of the first protrusion in the second direction, a tip end of the second protrusion is located within the recess and has a second protrusion that protrudes toward a bottom surface of the recess, The second protrusion is curved along the recess and abuts against the recess. Fuel cell stack.

2. The entire tip of the second convex portion is curved along the recessed portion. The fuel cell stack of claim 1 .

3. the plurality of first convex portions and the plurality of second convex portions are provided over an entire range in which the groove flow passage is formed in the second direction; 3. The fuel cell stack according to claim 1 or 2.

4. The first separator and the second separator are made of metal plates. The fuel cell stack according to any one of claims 1 to 3.

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