Fuel cell separator and fuel cell unit cell

Abstract

To provide a separator for a fuel cell and a single cell of a fuel cell capable of suppressing sinking of a gas diffusion layer into a groove flow channel.SOLUTION: A separator 30 for a fuel cell has an inside opposed surface 30a opposed to an MEA (Membrane Electrode Assembly) 10 of a fuel cell. The inside opposed surface 30a is provided with a plurality of ribs 38 located between groove flow channels 37 and protruded toward the MEA 10. Each rib 38 is provided with a recessed part 40 located at the center of the rib 38 in a third direction Z. The recessed part 40 has: a bottom face 41 extending in a surface direction of the MEA 10 so as to be opposed to the MEA 10; and a pair of inner lateral faces 42 rising from both ends of the bottom face 41 in the third direction Z. The pair of inner lateral faces 42 incline so as to be separated farther from the bottom face 41 in the third direction Z as they approach the MEA 10 in a first direction X.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a separator for a fuel cell and a unit cell of the fuel cell. [Background technology]

[0002] Patent Document 1 discloses a fuel cell. This fuel cell includes a membrane electrode gas diffusion layer assembly (hereinafter, MEGA) and a resin frame member disposed on the outer periphery of the MEGA.

[0003] The fuel cell also includes anode-side and cathode-side separators that sandwich the MEGA and the resin frame member. The MEGA includes a membrane electrode assembly (hereinafter, MEA) and anode-side and cathode-side gas diffusion layers (hereinafter, GDLs) that sandwich the MEA.

[0004] The separator has a plurality of groove channels that supply oxidizing gas or fuel gas (hereinafter, reactant gas) to the MEGA, and a plurality of ribs that are located between the groove channels and abut against the GDL. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-188346 A Summary of the Invention [Problem to be solved by the invention]

[0006] In such a fuel cell, the portion of the GDL adjacent to the separator that faces the groove may bend and sink into the groove, which may increase the pressure loss of the reactant gas because the sunken GDL acts as a resistance to the reactant gas flowing through the groove.

[0007] An object of the present invention is to provide a separator for a fuel cell and a unit cell of the fuel cell that can suppress sinking of a gas diffusion layer into groove flow paths. [Means for solving the problem]

[0008] A separator for a fuel cell to achieve the above-mentioned objective has an opposing surface facing a power generation unit of the fuel cell, and the opposing surface has a plurality of groove channels arranged side by side through which reactant gas flows, and the opposing surface has a plurality of ribs located between the groove channels and protruding toward the power generation unit, and the rib has a recess located at the center of the rib in the arrangement direction of the plurality of groove channels, and the recess has a bottom surface extending in the surface direction of the power generation unit and facing the power generation unit, and a pair of inner side surfaces rising from both ends of the bottom surface in the arrangement direction, and the pair of inner side surfaces are inclined so that they move away from the bottom surface in the arrangement direction as they approach the power generation unit in the opposing direction between the power generation unit and the separator.

[0009] In addition, a single cell of a fuel cell to achieve the above-mentioned objective comprises a pair of separators, and a power generation unit sandwiched between the pair of separators and having a pair of gas diffusion layers abutting each of the pair of separators, at least one of the pair of separators being the above-mentioned separator, and the power generation unit being sunk into the recess.

[0010] According to this configuration, when the power generation section and the separator are laminated to manufacture a single fuel cell, the gas diffusion layer (hereinafter, GDL) sinks into the recess along the pair of inner sides. As a result, the portion of the GDL facing the groove channel is in a taut state. Therefore, it is possible to suppress the sinking of the GDL into the groove channel. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view showing a unit cell of a fuel cell according to one embodiment of a separator for the fuel cell. [Diagram 2] FIG. 2 is a plan view showing the separator of the embodiment. [Diagram 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 the power generating section laminated on the separator. [Diagram 5] FIG. 5 is a cross-sectional view showing a state in which the GDL is sunk into the recess of the rib. [Figure 6] FIG. 6 is a cross-sectional view showing a state in which the frame member is sunk into the recessed portion of the rib. [Figure 7] FIG. 7 is a plan view showing a modified example of the separator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of a separator for a fuel cell and a single cell of the fuel cell will be described with reference to Figures 1 to 6. Note that in each drawing, for the sake of convenience, some of the components are shown exaggerated or simplified, and therefore the dimensional ratios of each component may differ from the actual ratios.

[0013] <Overall configuration of a single cell 90 of a fuel cell stack> As shown in FIG. 1, a single cell 90 of the fuel cell stack has a membrane electrode assembly 10 (hereinafter, MEA 10), a frame member 20 that holds the MEA 10, and a pair of separators 30, 50 that hold the MEA 10 and the frame member 20 therebetween.

[0014] The unit cell 90 has an overall rectangular plate shape. In the following description, the stacking direction of the separator 30, the MEA 10, the frame member 20, and the separator 50 is referred to as a first direction X.

[0015] Further, the longitudinal direction of the unit cell 90 and a direction perpendicular to the first direction X are referred to as a second direction Y in the following description. Moreover, a direction perpendicular to both the first direction X and the second direction Y is referred to as a third direction Z in the following description.

[0016] The single cell 90 has inlet holes 91, 93, and 95 for introducing a reactant gas or a cooling medium into the single cell 90, and outlet holes 92, 94, and 96 for discharging the reactant gas and the cooling medium in the single cell 90 to the outside. In this embodiment, the inlet hole 91 and the outlet hole 92 are holes through which a fuel gas flows. The inlet hole 93 and the outlet hole 94 are holes through which a cooling medium flows. The inlet hole 95 and the outlet hole 96 are holes through which an oxidizer gas flows. Here, the fuel gas is hydrogen gas. The cooling medium is cooling water. The oxidizer gas is air.

[0017] The inlet holes 91, 93, 95 and the outlet holes 92, 94, 96 have a rectangular shape in a plan view that is long in the second direction Y, and penetrate the unit cell 90 in the first direction X. The inlet hole 91 and the outlet holes 94, 96 are provided on one side of the unit cell 90 in the second direction Y (the left side in the left-right direction in FIG. 1). The inlet hole 91 and the outlet holes 94, 96 are arranged at intervals from each other in the third direction Z. The outlet hole 92 and the inlet holes 93, 95 are provided on the other side of the unit cell 90 in the second direction Y (the right side in FIG. 1). The outlet hole 92 and the inlet holes 93, 95 are arranged at intervals from each other in the third direction Z.

[0018] <mea10> As shown in FIG. 1, the MEA 10 has a rectangular shape that is long in the second direction Y when viewed from above. The MEA 10 has a solid polymer electrolyte membrane (hereinafter, electrolyte membrane) (not shown) and electrodes 11A, 11B provided on both sides of the electrolyte membrane. In this embodiment, the electrode bonded to one side (upper side in the vertical direction in FIG. 1) of the electrolyte membrane (not shown) in the first direction X is the cathode electrode 11A. The electrode bonded to the other side (lower side in FIG. 1) of the electrolyte membrane in the first direction X is the anode electrode 11B.

[0019] The electrodes 11A and 11B each have a catalyst layer (not shown) bonded to the electrolyte membrane, and a gas diffusion layer 12 (hereinafter, GDL 12) bonded to the catalyst layer. The MEA 10 corresponds to the power generating section of the fuel cell according to the present invention.

[0020] <Frame member 20> As shown in FIG. 1, the frame member 20 has a rectangular frame shape that is long in the second direction Y. The frame member 20 is formed in a sheet shape from, for example, a synthetic resin material.

[0021] The frame member 20 has through holes 21, 22, 23, 24, 25, and 26 which form the holes 91, 92, 93, 94, 95, and 96. The frame member 20 has an opening 27 in the center that is rectangular in plan view and elongated in the second direction Y. The MEA 10 is joined to the edge of the opening 27 from one side in the first direction X (the upper side in FIG. 1). In other words, the frame member 20 is located on the outer periphery of the MEA 10.

[0022] <Separator 30> As shown in FIGS. 1 and 2, the separator 30 has a rectangular plate shape that is elongated in the second direction Y when viewed from above.

[0023] The separator 30 is formed by press-molding a metal member such as titanium or stainless steel. The separator 30 is provided on the anode electrode 11B side of the MEA 10 (see FIG. 1).

[0024] The separator 30 has an inner facing surface 30 a facing the MEA 10 and an outer facing surface 30 b facing the frame member 20 . The separator 30 has through holes 31, 32, 33, 34, 35, and 36 which constitute the holes 91, 92, 93, 94, 95, and 96. The through holes 31, 34, and 36 are provided at positions corresponding to the through holes 21, 24, and 26 of the frame member 20 in the third direction Z. The through holes 32, 33, and 35 are provided at positions corresponding to the through holes 22, 23, and 25 of the frame member 20 in the third direction Z.

[0025] The separator 30 has a plurality of groove channels 37 through which the fuel gas flows, and a plurality of ribs 38 located between the groove channels 37. Note that Fig. 1 shows a simplified outer edge of the portion where the plurality of groove channels 37 and the plurality of ribs 38 are formed.

[0026] <Groove channel 37> 2, the plurality of groove channels 37 are grooves that connect the through holes 31 and 32. In this embodiment, six groove channels 37 are arranged in the third direction Z at intervals.

[0027] The groove width of the groove 37, i.e., the cross-sectional area of ​​the groove 37, is constant over the entirety in the extending direction of the groove 37. The groove widths of the grooves 37 are the same as each other. The six grooves 37 are composed of three first grooves 71 and three second grooves 72. The first grooves 71 and the second grooves 72 are alternately provided in the third direction Z.

[0028] The first groove flow passage 71 has a wavy portion 73 provided on the inner facing surface 30a, and an extending portion 75 extending from the wavy portion 73 to the outer facing surface 30b. The wavy portion 73 extends in a wavy manner in the planar direction of the inner facing surface 30a. The wavelength λ and amplitude A of the wavy portion 73 are constant throughout the extension direction of the wavy portion 73. The number of waves of the wavy portion 73 is three.

[0029] The extending portions 75 extend linearly from both ends of the corrugated portion 73 in the extending direction toward the through holes 31 and 32, respectively. The second groove flow passage 72 has a wavy portion 74 provided on the inner facing surface 30a and an extension portion 76 extending from the wavy portion 74 to the outer facing surface 30b. In this embodiment, the wavy portion 74 has the same waveform as the wavy portion 73.

[0030] The extending portions 76 extend linearly from both ends of the corrugated portion 74 in the extending direction toward the through holes 31 and 32, respectively. The groove 37 located outermost in the third direction Z among the plurality of grooves 37 has a portion located outside in the third direction Z relative to the outer edge of the inner facing surface 30a.

[0031] <Rib 38> As shown in FIG. 3, the multiple ribs 38 protrude to one side in the first direction X (upper side in the vertical direction in FIG. 3).

[0032] As shown in FIG. 2, in this embodiment, five ribs 38 are arranged in the third direction Z at intervals. Each rib 38 has a wavy portion 81 provided on the inner facing surface 30a and an extension portion 84 extending from the wavy portion 81 to the outer facing surface 30b. In this embodiment, the wavy portion 81 located outermost in the third direction Z among the multiple wavy portions 81 has a portion located outside the outer edge of the inner facing surface 30a.

[0033] The wavy portion 81 has a narrow portion 83 having a smaller width W in the third direction Z than other portions (hereinafter, general portions 82) in the wavy portion 81. In this embodiment, the narrow portion 83 is located between the apexes V1 and V2 of the wavy portion 81 and between the apexes V2 and V3 of the wavy portion 81 in the extension direction of the wavy portion 81.

[0034] 3, the rib 38 is provided with a recess 40 that opens toward the MEA 10. The recess 40 is provided in the center of the rib 38 in the third direction Z. The recess 40 has a bottom surface 41 that extends in the surface direction of the MEA 10 and faces the MEA 10, and a pair of inner side surfaces 42 that rise up from both ends of the bottom surface 41 in the third direction Z.

[0035] The height H from the bottom surface 41 to the tip of the rib 38 is preferably within a range of 10 μm to 30 μm. Moreover, the height H is more preferably within a range of 20 μm to 30 μm. In this embodiment, the height H is set to 20 μm to 30 μm.

[0036] The pair of inner sides 42 are inclined so as to move away from the bottom surface 41 in the third direction Z as they approach the MEA 10 in the first direction X. The inclination angle θ of the pair of inner sides 42 relative to the bottom surface 41 is preferably within a range of 1 degree or more and 5 degrees or less. Furthermore, the inclination angle θ is more preferably 2 degrees or more and 5 degrees or less. Furthermore, the inclination angle θ is even more preferably 3 degrees or more and 5 degrees or less. Furthermore, the inclination angle θ is even more preferably 4 degrees or more and 5 degrees or less. In this embodiment, the inclination angle θ is set to 4 degrees or more and 5 degrees or less.

[0037] As shown in Fig. 2, the recesses 40 are provided at multiple locations (four locations in this embodiment) in the extending direction of each rib 38. Two of the four recesses 40 are provided in the wavy portion 81 of the rib 38. More specifically, a recess 40 is provided in each of the two narrow width portions 83. The remaining two recesses 40 are provided in the extending portion 84 of the rib 38. More specifically, a recess 40 is provided in each of the extending portion 84 extending into the through hole 31 and the extending portion 84 extending into the through hole 32.

[0038] <Groove channel 38A, rib 37A> As shown in Fig. 1 and Fig. 3, the separator 30 has a surface 30c opposite to the opposing surfaces 30a, 30b in the first direction X. The surface 30c is provided with a plurality of groove channels 38A through which a cooling medium flows, and a plurality of ribs 37A located between the groove channels 38A. The ribs 37A are formed by the back surface of the groove channels 37. The groove channels 38A are formed by the back surface of the ribs 38. That is, the ribs 37A and the groove channels 38A are in a relationship of being in one with the groove channels 37 and the ribs 38 of the opposing surfaces 30a, 30b (see Fig. 3). Note that Fig. 1 shows a simplified outer edge of the portion where the plurality of groove channels 38A and the plurality of ribs 37A are formed.

[0039] The plurality of groove channels 38A are grooves that connect the through holes 33 and 34. In the groove channels 38A, the cooling medium flows in the opposite direction to the fuel gas flowing through the groove channels 37. <Separator 50> As shown in FIG. 1, the separator 50 has a rectangular plate shape that is elongated in the second direction Y when viewed from above.

[0040] The separator 50 is formed by press-molding a metal member such as titanium or stainless steel. The separator 50 is provided on the cathode electrode 11A side of the MEA 10. The separator 50 has a first surface 50a including a facing surface facing the MEA 10, and a second surface 50b opposite to the first surface 50a.

[0041] The separator 50 has through holes 51, 52, 53, 54, 55, and 56 which constitute the holes 91, 92, 93, 94, 95, and 96. The through holes 51, 54, and 56 are provided at positions corresponding to the through holes 21, 24, and 26 of the frame member 20 in the third direction Z. The through holes 52, 53, and 55 are provided at positions corresponding to the through holes 22, 23, and 25 of the frame member 20 in the third direction Z.

[0042] As shown in Fig. 1, the separator 50 has a plurality of groove channels 57 through which the oxidant gas flows, and a plurality of groove channels 58 through which the coolant flows. Note that Fig. 1 shows a simplified view of the outer edge of the portion of the separator 50 where the plurality of groove channels 57 are formed, and the outer edge of the portion of the separator 50 where the plurality of groove channels 58 are formed.

[0043] The plurality of grooves 57 are grooves that connect the through holes 55 and 56. In the grooves 57, the oxidant gas flows in the opposite direction to the fuel gas flowing in the grooves 37. The plurality of groove channels 58 are grooves that connect the through holes 53 and the through holes 54. In the groove channels 58, the coolant flows in the same direction as the oxidant gas flowing through the groove channels 57.

[0044] Next, the operation of this embodiment will be described. As shown in Figures 4 and 5, when the separator 30, the MEA 10, and the frame member 20 are laminated to manufacture a single fuel cell 90, the GDL 12 sinks into the recess 40 along a pair of inner sides 42 on the inner facing surface 30a of the separator 30. The GDL 12 also comes into contact with the bottom surface 41 of the recess 40. As a result, the portion of the GDL 12 facing the groove flow passage 37 is in a taut state. Note that only the GDL 12 of the MEA 10 is shown in Figures 4 and 5.

[0045] 6, on the outer facing surface 30b of the separator 30, the frame member 20 sinks into the recess 40 along a pair of inner sides 42. The frame member 20 also comes into contact with the bottom surface 41 of the recess 40. As a result, the portion of the frame member 20 facing the groove flow passage 37 is in a tensed state.

[0046] Next, the effects of this embodiment will be described. (1) The separator 30 has an inner facing surface 30a that faces the MEA 10 of the fuel cell. The inner facing surface 30a is provided with a plurality of ribs 38 that are located between the groove channels 37 and that protrude toward the MEA 10. The ribs 38 are provided with recesses 40 that are located at the centers of the ribs 38 in the third direction Z. The recesses 40 have a bottom surface 41 that extends in the surface direction of the MEA 10 and faces the MEA 10, and a pair of inner side surfaces 42 that rise from both ends of the bottom surface 41 in the third direction Z. The pair of inner side surfaces 42 are inclined so as to move away from the bottom surface 41 in the third direction Z as they approach the MEA 10 in the first direction X.

[0047] This configuration provides the above-mentioned effects, and therefore, the sinking of the GDL 12 into the groove channel 37 can be suppressed. (2) The height H from the bottom surface 41 of the recess 40 to the tip of the rib 38 is 20 μm or more and 30 μm or less. The inclination angle θ of the pair of inner side surfaces 42 with respect to the bottom surface 41 is 4 degrees or more and 5 degrees or less.

[0048] According to this configuration, the effect of the invention according to (1) can be preferably exhibited, and the occurrence of a gap between the bottom surface 41 of the recess 40 and the GDL 12 can be preferably suppressed.

[0049] (3) The recesses 40 are provided at a plurality of positions on the inner facing surface 30a in the direction in which the ribs 38 extend. According to this configuration, the effect of (1) can be achieved at a plurality of positions in the extending direction of the rib 38. Therefore, sinking of the GDL 12 into the groove flow passage 37 can be further suppressed.

[0050] (4) The multiple groove channels 37 each extend in a wavy manner in the planar direction of the inner opposing surface 30a and have a first groove channel 71 and a second groove channel 72 adjacent to each other in the third direction Z. The multiple ribs 38 each have a wavy portion 81 located between the first groove channel 71 and the second groove channel 72. The wavy portion 81 has a narrow portion 83 whose width W in the third direction Z is smaller than that of a general portion 82 in the wavy portion 81. The recesses 40 are provided in the narrow portion 83.

[0051] The sinking of the GDL 12 into the groove channel 37 is more likely to occur as the width W in the third direction Z of the rib 38 adjacent to the groove channel 37 is smaller. In this regard, according to the above-mentioned configuration, the recess 40 is provided in the narrow portion 83 of the rib 38. Therefore, in the portion of the first groove channel 71 and the second groove channel 72 adjacent to the narrow portion 83, i.e., in the portion where the GDL 12 is likely to sink into the groove channel 37, the GDL 12 facing the portion can be kept taut. Therefore, the sinking of the GDL 12 into the groove channel 37 can be suppressed.

[0052] According to the above configuration, the separator 30 has the first groove 71 and the second groove 72 extending in a wavy shape. Therefore, when the unit cells 90 are stacked, the contact area between the separator 30 in one unit cell 90 and the separator 50 in the other unit cell 90 is increased compared to a case where the grooves 37 of the separator 30 extend linearly in the planar direction of the inner facing surface 30a. This improves the stability of the contact structure between the adjacent separators 30, 50, and therefore the stability of the contact structure between the unit cells 90.

[0053] (5) The recesses 40 are provided in each of the multiple ribs 38 . According to this configuration, for each of the plurality of grooves 37, sinking of the GDLs 12 into the grooves 37 can be suppressed.

[0054] (6) The separator 30 has an outer surface 30b that faces the frame member 20. The grooves 37 and the ribs 38 each have extending portions 75, 76, 84 that extend to the outer surface 30b. The recesses 40 are also provided in the extending portion 84.

[0055] In the fuel cell, the MEA 10 is held by a frame member 20 located on the outer periphery of the MEA 10. If the frame member 20 is made of a synthetic resin material, the portion of the frame member 20 facing the groove flow passage 37 may bend and deform, and sink into the groove flow passage 37. In this case, the sunken frame member 20, like the GDL 12, provides resistance to the fuel gas flowing through the groove flow passage 37, and may increase the pressure loss of the fuel gas.

[0056] In this regard, the above-described configuration exerts an effect similar to that of the above-described invention, so that sinking of the frame member 20 into the groove flow passage 37 can be suppressed. <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0057] The shapes of the inlet holes 91, 93, 95 and the outlet holes 92, 94, 96 are not limited to the rectangular shape in plan view as exemplified in this embodiment. For example, the shapes of the inlet holes 91, 93, 95 and the outlet holes 92, 94, 96 may be square or elliptical in plan view.

[0058] The flows of the reactant gas and the coolant in the holes 91, 92, 93, 94, 95, and 96 are not limited to those exemplified in this embodiment, and for example, the hole 96 may be an oxidant gas inlet hole and the hole 95 may be an oxidant gas outlet hole. Additionally, the hole 94 may be a coolant inlet hole and the hole 93 may be a coolant outlet hole. In other words, the oxidant gas flowing through the groove flow passage 57 and the coolant flowing through the groove flow passages 38A and 58 may flow in the same direction as the fuel gas flowing through the groove flow passage 37.

[0059] The number of grooves 37 is not limited to six as exemplified in this embodiment, but may be five or less, or seven or more. The groove width of each of the grooves 37, that is, the cross-sectional area of ​​the grooves 37, does not have to be constant over the entire length of the grooves 37 in the extension direction, so long as the advantageous effects of the present invention are achieved.

[0060] The separator 30 is not limited to the one in which the groove 37 located most outside in the third direction Z among the plurality of grooves 37 has a portion located outside the outer edge of the inner facing surface 30a as exemplified in this embodiment. For example, the groove 37 may be located at the same position as the outer edge of the inner facing surface 30a in the third direction Z, or may be located inside the outer edge. In addition, accordingly, the wavy portion 81 located most outside in the third direction Z among the wavy portions 81 of the plurality of ribs 38 may be located inside the outer edge of the inner facing surface 30a.

[0061] The recesses 40 do not have to be provided in each of the ribs 38 as illustrated in this embodiment, but may be provided in at least one of the ribs 38 . The separator 30 is not limited to the one in which the recesses 40 are provided only in the narrow portions 83 of the wavy portions 81 of the ribs 38 as exemplified in this embodiment. For example, the recesses 40 may be provided in both the narrow portions 83 and the general portions 82 of the wavy portions 81, or may be provided only in the general portions 82.

[0062] The plurality of groove channels 37 is not limited to being composed of a plurality of first groove channels 71 and a plurality of second groove channels 72. For example, the plurality of groove channels 37 may have at least one each of the first groove channels 71 and the second groove channels 72 adjacent to each other, and may also have groove channels other than the first groove channels 71 and the second groove channels 72.

[0063] The second groove flow passage 72 is not limited to the wave-like portion 74 having the same waveform as the wave-like portion 73 of the first groove flow passage 71 as exemplified in this embodiment, and the wavelength λ, amplitude A, and wave number of the wave-like portion 74 may be appropriately changed to be different from those of the wave-like portion 73. In this case, the narrow width portion 83 of the rib 38 does not have to be located between the apexes V1, V2 and between the apexes V2, V3 of the wave-like portion 81 as exemplified in this embodiment.

[0064] The shape of the first groove flow passage 71 is not limited to the shape exemplified in this embodiment. That is, the first groove flow passage 71 is not limited to one in which the wavelength λ and amplitude A of the wavy portion 73 are constant over the entire extension direction of the wavy portion 73, and may be one in which the wavelengths λ and amplitudes A of the three waves of the wavy portion 73 are different from each other.

[0065] The number of waves of the wavy portion 73 is not limited to three as exemplified in this embodiment, but may be two or less, or may be four or more. The recesses 40 are not limited to those provided at a plurality of positions on the inner facing surface 30a in the extending direction of the rib 38 as exemplified in this embodiment. That is, as shown in Fig. 7, the recesses 40 may be provided over the entire extending direction of the corrugated portion 81. In this case, the recesses 40 provided in the extending portion 84 may extend from the recesses 40 provided in the corrugated portion 81, or may be provided independently (see Fig. 7). Also, the recesses 40 may be omitted from the extending portion 84.

[0066] The shape of the grooves 37 is not limited to the shape exemplified in this embodiment, and may be appropriately modified as follows: That is, the grooves 37 are not limited to the first grooves 71 and the second grooves 72 each extending in a wavy manner in the surface direction of the inner facing surface 30a, and each of the grooves 37 may be modified to extend linearly in the surface direction of the inner facing surface 30a, for example.

[0067] The separator for a fuel cell according to the present invention is not limited to the separator 30 joined to the anode electrode 11B side of the MEA 10 as exemplified in this embodiment, but can also be applied to a separator 50 joined to the cathode electrode 11A side.

[0068] The separators 30, 50 are not limited to those formed by press molding a metal member, but may also be formed by cutting or etching, for example. The material used for the separators 30, 50 is not limited to titanium or stainless steel, but may also be aluminum or carbon. [Explanation of symbols]

[0069] θ…Inclination angle λ...Wavelength A…Amplitude H…Height V1,V2,V3…Vertex W…width X…first direction Y: Second direction Z...Third direction 10...Membrane electrode assembly, MEA 11A…Cathode electrode 11B…Anode electrode 12...Gas diffusion layer, GDL 20...Frame member 21...Through hole 22...Through hole 23...Through hole 24...Through hole 25...Through hole 26...Through hole 27…Opening 30…Separator 30a...Inner facing surface 30b…Outside facing surface 30c...side 31...Through hole 32...Through hole 33...Through hole 34...Through hole 35...Through hole 36…Through hole 37…Groove channel 37A…Rib 38…Rib 38A…Groove channel 40…Recess 41…Bottom 42…Inner surface 50…Separator 50a…Side 1 50b…Second side 51...Through hole 52...Through hole 53...Through hole 54...Through hole 55...Through hole 56…Through hole 57…Groove channel 58...Groove channel 71...First groove channel 72…Second groove channel 73…Wavy part 74…Wavy part 75...Extending part 76...Extending part 81…Wavy part 82…General section 83…Narrow part 84...Extension part 90...single cell 91...Inlet hole 92...Inlet hole 93...Inlet hole 94...Outlet hole 95...Outlet hole 96…Outlet hole

Claims

1. A separator for a fuel cell having a surface facing a power generation section of the fuel cell, the surface being provided with a plurality of groove channels arranged side by side through which a reactant gas flows, a plurality of ribs are provided on the opposing surface, the ribs being positioned between the groove channels and protruding toward the power generation section; The rib is provided with a recess located at a center of the rib in an arrangement direction of the plurality of grooves, the recess has a bottom surface extending in a surface direction of the power generating unit and facing the power generating unit, and a pair of inner side surfaces rising from both ends of the bottom surface in the arrangement direction, the pair of inner side surfaces are inclined so as to move away from the bottom surface in the arrangement direction as they approach the power generation section in the opposing direction of the power generation section and the separator. A separator for fuel cells.

2. A height from the bottom surface of the recess to the tip of the rib is 10 μm or more and 30 μm or less, The inclination angle of the pair of inner sides with respect to the bottom surface is 1 degree or more and 5 degrees or less. The separator for a fuel cell according to claim 1 .

3. The recesses are provided at a plurality of locations on the opposing surface in the extending direction of the rib.

3. The separator for a fuel cell according to claim 1 or 2.

4. The plurality of grooves each include a first groove and a second groove that extend in a wavy manner in a planar direction of the opposing surface and are adjacent to each other in the arrangement direction, The plurality of ribs have a wavy portion located between the first groove and the second groove, The wavy portion has a narrow portion having a smaller width in the arrangement direction than other portions of the wavy portion, The recess is provided in the narrow portion. The separator for a fuel cell according to any one of claims 1 to 3.

5. The recess is provided in each of the plurality of ribs. The separator for a fuel cell according to any one of claims 1 to 4.

6. the power generation unit is held by a frame member located on an outer periphery of the power generation unit, When the facing surface is an inner facing surface, an outer facing surface facing the frame member; The plurality of grooves and the plurality of ribs each have an extension portion extending to the outer facing surface, The recess is also provided in the extension portion. The separator for a fuel cell according to any one of claims 1 to 5.

7. A pair of separators; a power generation section that is sandwiched between the pair of separators and has a pair of gas diffusion layers that are in contact with the pair of separators, At least one of the pair of separators is the separator according to any one of claims 1 to 6, The power generating unit is recessed into the recess. A single fuel cell.

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