Bipolar plate and method for producing same

Abstract

The present invention addresses the problem of facilitating joining work between a first separator (2A) and a second separator (2B).　A bipolar plate (1) is characterized by comprising: a first separator (2A); a second separator (2B) that is laminated on the first separator (2A); and joining parts (30-32) that are composed of an elastomer and join surfaces which do not face each other among given surfaces of the first separator (2A) and given surfaces of the second separator (2B).

Description

Bipolar plate and manufacturing method thereof

[0001] The present disclosure relates to bipolar plates for fuel cells and methods of making the same.

[0002] The pair of separators in the fuel cell described in Patent Document 1 are joined and stacked by welding.The pair of separators in the fuel cell described in Patent Document 2 are joined and stacked by adhesive.

[0003] International Publication No. 2018 / 034085 Pamphlet Japanese Patent Application Laid-Open No. 2007-35442

[0004] When joining a pair of separators by welding or adhesive bonding, the pair of separators must be pressed against each other in the stacking direction. When pressing the separators together, the pressing accuracy (contact area between the pair of separators, pressing load, etc.) must be carefully controlled. Therefore, the joining process is complicated. Therefore, the bipolar plate and its manufacturing method disclosed herein aim to facilitate the joining process of a pair of separators.

[0005] (1) In order to solve the above problem, the bipolar plate of the present disclosure is characterized by comprising a first separator, a second separator stacked on the first separator, and an elastomeric connecting portion connecting any surfaces of the first separator and any surfaces of the second separator that do not face each other.

[0006] According to this configuration, the connecting portion connects any surface of the first separator and any surface of the second separator that do not face each other. This reduces the burden of managing the accuracy of pressing the first separator and the second separator together, thereby facilitating the joining process of the first separator and the second separator.

[0007] The connecting portion made of elastomer has elasticity, so even if springback occurs in the first separator or the second separator during bonding, the elastic deformation of the connecting portion can absorb at least a portion of the springback.

[0008] (1-1) In the configuration of (1) above, where the direction in which the first separator and the second separator are stacked is defined as the stacking direction, the first separator has a first opposing surface facing the second separator in the stacking direction and a first non-opposing surface that does not face the second separator in the stacking direction, and the second separator has a second opposing surface facing the first separator in the stacking direction and a second non-opposing surface that does not face the first separator in the stacking direction, and it is preferable that the connecting portion connects surfaces of at least one combination of the following combinations (A) to (C): (A) The first non-opposing surface and the second non-opposing surface. (B) The first opposing surface and the second non-opposing surface. (C) The first non-opposing surface and the second opposing surface.

[0009] According to this configuration, the connecting portion connects the surfaces of at least one combination of the above combinations (A) to (C), i.e., the surfaces of a combination other than the "first opposing surface and the second opposing surface." This reduces the burden of managing the pressing accuracy between the first separator and the second separator. This makes it easier to join the first separator and the second separator.

[0010] (2) In any of the above configurations, it is preferable that, with the direction in which the first separator and the second separator are stacked being taken as the stacking direction, the first separator has a first through hole penetrating the first separator in the stacking direction, the second separator has a second through hole penetrating the second separator in the stacking direction, the first through hole and the second through hole overlap each other entirely or partially as seen from the stacking direction, the connecting portion is disposed across the first through hole and the second through hole, and the first separator and the second separator are integrated via the connecting portion. According to this configuration, the first separator and the second separator can be integrated by utilizing the internal space of the first through hole and the internal space of the second through hole.

[0011] (3) In the configuration of (2) above, it is preferable that the first through hole has, when viewed from the stacking direction, a first overlapping portion that overlaps with the second through hole and a first non-overlapping portion that does not overlap with the second through hole, and the second through hole has, when viewed from the stacking direction, a second overlapping portion that overlaps with the first through hole and a second non-overlapping portion that does not overlap with the first through hole, and that the first non-overlapping portion and the second non-overlapping portion extend in different directions from each other.

[0012] Here, "different directions" includes any X direction (e.g., the front-to-back direction) and a Y direction (e.g., the left-to-right direction) that intersects with the X direction. Furthermore, "different directions" also includes the X+ direction (forward direction) and the X- direction (rearward direction) within the same X direction (e.g., the front-to-back direction). The same applies to the Y direction. According to this configuration, the first non-overlapping portion and the second non-overlapping portion can extend in different directions from each other, starting from the first overlapping portion and the second overlapping portion. Therefore, the connecting portion can be deployed along the first non-overlapping portion and the second non-overlapping portion in a direction that intersects with the stacking direction.

[0013] (4) In the configuration of (3) above, it is preferable that the first through hole has a plurality of the first overlapping portions, that a plurality of the second through holes are arranged, that the plurality of first overlapping portions each communicate with a different second through hole, and that the connecting portion be arranged via the first through hole and the plurality of second through holes.

[0014] According to this configuration, a single first through hole can be connected to a plurality of second through holes. Therefore, the connecting portion can be arranged to pass through these through holes (first through hole, second through hole). Therefore, the first separator and the second separator can be joined as if sewn together.

[0015] (5) In the configuration of (3) above, it is preferable that the second through hole has a plurality of the second overlapping portions, that a plurality of the first through holes are arranged, that the plurality of second overlapping portions each communicate with a different one of the first through holes, and that the connecting portion be arranged via the second through hole and the plurality of the first through holes.

[0016] According to this configuration, a single second through hole can be connected to a plurality of first through holes. Therefore, the connecting portion can be arranged to pass through these through holes (first through hole, second through hole). Therefore, the first separator and the second separator can be joined as if sewn together.

[0017] (6) In any of the above configurations, it is preferable that the connecting portion is filled in at least one of the first through hole and the second through hole. With this configuration, the volume of the connecting portion can be increased compared to when the connecting portion is not filled in the first through hole and the second through hole. Furthermore, the connecting portion is bonded over the entire inner circumferential surface of the filled through hole (at least one of the first through hole and the second through hole that is filled with the connecting portion). This allows the first separator and the second separator to be firmly bonded.

[0018] (7) In any of the above configurations, it is preferable that the first separator has a first opposing surface facing the second separator in the stacking direction and a first non-opposing surface that does not face the second separator in the stacking direction, the second separator has a second opposing surface facing the first separator in the stacking direction and a second non-opposing surface that does not face the first separator in the stacking direction, the inner circumferential surface of the first through hole is included in the first non-opposing surface, and the connecting portion housed in the first through hole connects the inner circumferential surface of the first through hole to the second opposing surface. According to this configuration, the inner circumferential surface of the first through hole (first non-opposing surface) can be connected to the second opposing surface via the connecting portion.

[0019] (8) In any of the above configurations, it is preferable that the first separator has a first opposing surface facing the second separator in the stacking direction and a first non-opposing surface that does not face the second separator in the stacking direction, the second separator has a second opposing surface facing the first separator in the stacking direction and a second non-opposing surface that does not face the first separator in the stacking direction, the inner circumferential surface of the second through hole is included in the second non-opposing surface, and the connecting portion housed in the second through hole connects the inner circumferential surface of the second through hole to the first opposing surface. According to this configuration, the inner circumferential surface of the second through hole (the second non-opposing surface) can be connected to the first opposing surface via the connecting portion.

[0020] (9) In any of the above configurations, the first through holes and the second through holes are preferably connected without any gaps in the stacking direction. This configuration allows the thickness of the bipolar plate in the stacking direction to be smaller than when there is a gap between the first through holes and the second through holes (specifically, when a connecting portion is interposed between the first separator and the second separator).

[0021] (10) In any of the above configurations, the direction in which the first separator and the second separator are stacked is the stacking direction, and a cooling flow path through which a coolant flows is defined between the first separator and the second separator, and when viewed from the stacking direction, the connecting portion is preferably configured to have an endless ring shape surrounding the cooling flow path.

[0022] According to this configuration, the first separator and the second separator can be joined via the connecting portion. The endless annular connecting portion can also seal the cooling flow passage. That is, the joining operation of the first separator and the second separator and the sealing operation of the cooling flow passage can be performed in parallel. Therefore, compared to when the joining operation and the sealing operation are performed separately, the bipolar plate manufacturing time can be shortened and the manufacturing man-hours can be reduced.

[0023] (11) In any of the above configurations, the direction in which the first separator and the second separator are stacked is the stacking direction, and a cooling flow path through which a coolant flows is defined between the first separator and the second separator, and the first separator has a first cooling surface which is the surface on the cooling flow path side and a first gas surface which faces away from the first cooling surface, and the second separator has a second cooling surface which is the surface on the cooling flow path side and a second gas surface which faces away from the second cooling surface, and it is preferable that the configuration further includes a gasket which protrudes outward in the stacking direction from at least one of the first gas surface and the second gas surface and is integrally connected to the connecting portion.

[0024] According to this configuration, the first separator and the second separator can be joined via the connecting portion. Furthermore, the gasket can be produced from the connecting portion. That is, the joining operation of the first separator and the second separator and the production operation of the gasket can be performed in parallel. Therefore, compared to when the joining operation and the production operation are performed separately, the manufacturing time of the bipolar plate can be shortened and the manufacturing man-hours can be reduced.

[0025] (12) In any of the configurations (1) to (10) above, the direction in which the first separator and the second separator are stacked is the stacking direction, and a cooling flow path through which a coolant flows is defined between the first separator and the second separator, and the first separator has a first cooling surface which is the surface on the cooling flow path side and a first gas surface which faces away from the first cooling surface, and the second separator has a second cooling surface which is the surface on the cooling flow path side and a second gas surface which faces away from the second cooling surface, and further, it is preferable to have a configuration in which a gasket which protrudes outward in the stacking direction from at least one of the first gas surface and the second gas surface and is separate from the connecting portion is provided.

[0026] In this configuration, the connecting portion and the gasket are separate bodies, which allows for greater design freedom (freedom of choice of shape, size, material, etc.) for the connecting portion and the gasket compared to when the connecting portion and the gasket are integrally connected.

[0027] (13) In the configuration of (11) or (12) above, a power generation unit of the fuel cell is disposed on both outer sides of the first separator and the second separator in the stacking direction, the gasket protrudes from the first gas surface and the second gas surface on both outer sides in the stacking direction, a first gas flow path through which one of a hydrogen-containing gas and an oxygen-containing gas flows is defined between the first separator and the power generation unit, and a second gas flow path through which the other of the hydrogen-containing gas and the oxygen-containing gas flows is defined between the second separator and the power generation unit, and it is preferable that the gasket has an endless ring shape surrounding the first gas flow path and the second gas flow path when viewed in the stacking direction.

[0028] According to this configuration, the first gas flow path can be sealed by the gasket on the first gas surface side (first separator side), and the second gas flow path can be sealed by the gasket on the second gas surface side (second separator side).

[0029] (14) In the configuration of (13) above, the direction perpendicular to the extension direction of the gasket on the first gas surface and the second gas surface is defined as the short-side direction, and the gasket is preferably configured to have a width in the short-side direction greater than that of the connecting portion.

[0030] According to this configuration, the gasket has a width in the short direction greater than that of the connecting portion, which makes it possible to prevent gas (hydrogen-containing gas, oxygen-containing gas) from leaking from the flow paths (first gas flow path, second gas flow path) across the gasket to the outside.

[0031] (15) In order to solve the above problem, the manufacturing method of a bipolar plate disclosed herein is a manufacturing method of a bipolar plate having the configuration of (2) above, characterized in that the first separator and the second separator are arranged in a molding die so that the first through hole and the second through hole overlap each other in whole or in part when viewed from the stacking direction, raw material for the connecting portion is injected into the die and hardened to form the connecting portion, and the first separator and the second separator are integrated via the connecting portion.

[0032] According to this configuration, the connecting portions are formed in the inner spaces of the first through-holes and the second through-holes, and the first separator and the second separator can be integrated by the connecting portions.

[0033] (16) In the configuration of (15) above, it is preferable that the bipolar plate has a gasket that is integrally connected to the connecting portion, the raw material is the raw material of the connecting portion and the gasket, the molding die has a gasket-molding recess that molds the gasket, and in a mold-closed state, the gasket-molding recess communicates with the first through hole and the second through hole, and the raw material is injected into the mold and hardened to mold the gasket together with the connecting portion.

[0034] According to this configuration, the joining operation of the first separator and the second separator and the manufacturing operation of the gasket can be performed in parallel, which shortens the manufacturing time of the bipolar plate and reduces the number of manufacturing steps compared to when the joining operation and the manufacturing operation are performed separately.

[0035] The bipolar plate and manufacturing method thereof of the present disclosure can facilitate the joining of a pair of separators.

[0036] FIG. 1 is a partial vertical cross-sectional view of a fuel cell stack including a bipolar plate according to a first embodiment. FIG. 2 is a top view of the bipolar plate. FIG. 3 is a bottom view of a first separator of the bipolar plate. FIG. 4 is a top view of a second separator of the bipolar plate. FIG. 5 is a bottom view of the bipolar plate. FIG. 6 is a top view of the first separator alone. FIG. 7 is a top view of the second separator alone. FIG. 8 is an exploded perspective view of the first and second separators connected via a slit connector. FIG. 9 is an exploded perspective view of the first and second separators connected via a spot-hole connector. FIG. 10 is an exploded perspective view of the first and second separators connected via a manifold connector. FIG. 11 is an enlarged view of the area enclosed by frame XI in FIG. 2. FIG. 12 is a cross-sectional view taken along the line XII-XII in FIG. 11. FIG. 13 is an enlarged view of the area enclosed by frame XIII in FIG. 2. Figure 14 is a cross-sectional view taken along the line XIV-XIV in Figure 13. Figure 15 is an enlarged view of the area within frame XV in Figure 2. Figure 16 is a cross-sectional view taken along the line XVI-XVI in Figure 15. Figure 17 is a partial cross-sectional view in the vertical direction of a mold used to manufacture the bipolar plate in an open state. Figure 18 is a partial cross-sectional view in the vertical direction of the mold in a clamped state (at the beginning of the injection process). Figure 19 is a partial cross-sectional view in the vertical direction of the mold in a clamped state (at the end of the vulcanization process). Figure 20 is a partial cross-sectional view in the vertical direction of a bipolar plate of a second embodiment. Figure 21 is a partial cross-sectional view in the vertical direction of a bipolar plate of a third embodiment.

[0037] Hereinafter, embodiments of the bipolar plate and the manufacturing method thereof according to the present disclosure will be described.

[0038] First Embodiment [Bipolar Plate Arrangement] First, the arrangement of bipolar plates in this embodiment will be described. In the following figures, the vertical direction corresponds to the "stacking direction" in this disclosure. Fig. 1 shows a vertical partial cross-sectional view of a fuel cell stack equipped with bipolar plates in this embodiment. As shown in Fig. 1, in the stack 9, multiple bipolar plates 1 and multiple power generation sections 8 are stacked alternately in the vertical direction (stacking direction).

[0039] Focusing on any bipolar plate 1, a pair of power generation units 8 are stacked on both the top and bottom sides of the bipolar plate 1. The power generation unit 8 includes a membrane electrode assembly 80 and a pair of gas diffusion layers 81. The membrane electrode assembly 80 includes an electrolyte membrane 800 and a pair of electrodes 801. The pair of electrodes 801 are stacked on both the top and bottom sides of the electrolyte membrane 800. The electrode 801 on the lower side (one side in the stacking direction) is an anode (fuel electrode). The electrode 801 on the upper side (the other side in the stacking direction) is a cathode (air electrode). The pair of gas diffusion layers 81 are stacked on both the top and bottom sides of the pair of electrodes 801.

[0040] [Bipolar Plate Configuration] Next, the configuration of the bipolar plate of this embodiment will be described. FIG. 2 shows a top view of the bipolar plate (top view of the first separator of the bipolar plate). FIG. 3 shows a bottom view of the first separator. FIG. 4 shows a top view of the second separator of the bipolar plate. FIG. 5 shows a bottom view of the bipolar plate (bottom view of the second separator). FIG. 6 shows a top view of the first separator alone. FIG. 7 shows a top view of the second separator alone. FIG. 8 shows an exploded perspective view of the first separator and the second separator connected via a slit connector. FIG. 9 shows an exploded perspective view of the first separator and the second separator connected via a spot hole connector. FIG. 10 shows an exploded perspective view of the first separator and the second separator connected via a manifold connector. FIG. 11 shows an enlarged view of the area within frame XI in FIG. 2. Fig. 12 shows a cross-sectional view taken along the line XII-XII in Fig. 11. Fig. 13 shows an enlarged view of the area enclosed by the frame XIII in Fig. 2. Fig. 14 shows a cross-sectional view taken along the line XIV-XIV in Fig. 13. Fig. 15 shows an enlarged view of the area enclosed by the frame XV in Fig. 2. Fig. 16 shows a cross-sectional view taken along the line XVI-XVI in Fig. 15.

[0041] Fig. 2 is a view seen from the direction of arrow YII in Fig. 1. Fig. 3 is a view seen from the direction of arrow YIII in Fig. 1. Fig. 4 is a view seen from the direction of arrow YIV in Fig. 1. Fig. 5 is a view seen from the direction of arrow YV in Fig. 1. Regarding the orientation in the figures, Figs. 3 and 5 are opposite in front-to-back direction to Figs. 2 and 4.

[0042] 12, 14, and 16, the thickness of each component in the vertical direction is emphasized. In Fig. 11, the first slits 25A (solid lines) and the second slits 25B (dotted lines) are shown through the first slit gasket 40A. In Fig. 13, the first spot hole 27A (solid lines) and the second spot hole 27B (solid lines) are shown through the first spot hole gasket 41A.

[0043] Regarding the symbols in the figures, the first separator 2A and the second separator 2B have corresponding symbols (numeric and alphabetic parts). Specifically, the numeric parts of the symbols match between corresponding parts of the first separator 2A and the second separator 2B (parts with corresponding arrangements and configurations). The alphabetic parts of the symbols differ ("A" for the first separator 2A and "B" for the second separator 2B).

[0044] As shown in Figures 1 to 16, the bipolar plate 1 includes a first separator 2A, a second separator 2B, connecting portions (a slit connecting portion 30, eight spot hole connecting portions 31, and four manifold connecting portions 32), and gaskets (a first slit gasket 40A, a second slit gasket 40B, two first spot hole gaskets 41A, two second spot hole gaskets 41B, four first manifold gaskets 42A, and four second manifold gaskets 42B).

[0045] (First Separator 2A) The first separator 2A is an anode (fuel electrode) side separator. As shown in Figures 2, 3, and 6, the first separator 2A is made of metal and has a rectangular thin plate shape. The first separator 2A includes a first concave-convex portion 20A, a lower surface (inner surface in the stacking direction) 21A, an upper surface (outer surface in the stacking direction) 22A, a first opposing surface 23A, a first non-opposing surface 24A, a plurality of first slits 25A, six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB, and eight first spot holes 27A.

[0046] When viewed from the top-bottom direction (in a plan view), the first uneven portion 20A is disposed in the center of the first separator 2A. The first uneven portion 20A has a rectangular shape. The first uneven portion 20A has a plurality of rib-shaped convex portions and a plurality of groove-shaped concave portions. The plurality of convex portions and the plurality of concave portions are arranged alternately. The first opposing surface 23A is disposed on the lower surface 21A. The lower surface 21A is included in the concept of the "first cooling surface" in the present disclosure. The first opposing surface 23A faces the second opposing surface 23B of the second separator 2B, which will be described later, in the top-bottom direction.

[0047] The upper surface 22A faces away from the lower surface 21A. The upper surface 22A is included in the concept of a "first gas surface" in the present disclosure. A first gas flow path P1 (see Figures 17 to 19 described below) is defined between a portion of the upper surface 22A corresponding to the first uneven portion 20A and a portion of the power generation section 8 shown in Figure 1 that overlaps with the first uneven portion 20A. A fuel gas flows through the first gas flow path P1. The fuel gas is included in the concept of a "hydrogen-containing gas" in the present disclosure.

[0048] 12 , 14 , and 16 , the first non-opposing surface 24A is the surface of the outer surface of the first separator 2A (including the inner circumferential surfaces of first slits 25A, which will be described later, the inner circumferential surfaces of first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB, and the inner circumferential surfaces of first spot holes 27A) other than the first opposing surface 23A. The first non-opposing surface 24A does not face a second opposing surface 23B of the second separator 2B, which will be described later, in the up-down direction.

[0049] Each of the multiple first slits 25A is included in the concept of a "first through hole" in the present disclosure. As shown in Figures 2 to 3 and 8 to 12, the first slits 25A penetrate the first separator 2A in the up-down direction. When viewed from the up-down direction, the first slits 25A have an elongated hole shape. The multiple first slits 25A are arranged consecutively at predetermined intervals along the rectangular outer edge of the first separator 2A.

[0050] As shown in FIGS. 11 and 12 , the first slit 25A includes two first overlapping portions 250A and a first non-overlapping portion 251A. The two first overlapping portions 250A are located at both longitudinal ends of the first slit 25A. When viewed from the top-bottom direction, the first overlapping portion 250A overlaps with a second overlapping portion 250B of the second slit 25B, which will be described later. The first non-overlapping portion 251A is located between the two first overlapping portions 250A. When viewed from the top-bottom direction, the first non-overlapping portion 251A does not overlap with the second overlapping portion 250B of the second slit 25B, which will be described later. The first non-overlapping portion 251A is covered from below by the upper surface 21B (second opposing surface 23B) of the second separator 2B, which will be described later.

[0051] 2 to 3 and 8 to 10 , six (plural) first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB each penetrate the first separator 2A in the up-down direction. Of the six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB, three first manifolds 26ALF, 26ALM, and 26ALB are disposed on the left side of the first concave-convex portion 20A. The three first manifolds 26ALF, 26ALM, and 26ALB are disposed in the following order from the front side to the rear side: first manifold 26ALF, first manifold 26ALM, and first manifold 26ALB.

[0052] Similarly, the remaining three first manifolds 26ARF, 26ARM, and 26ARB are disposed on the right side of the first uneven portion 20A. The three first manifolds 26ARF, 26ARM, and 26ARB are disposed in the following order from the front side to the rear side: first manifold 26ARF, first manifold 26ARM, and first manifold 26ARB.

[0053] Of the six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB, the four rectangular first manifolds 26ALF, 26ALB, 26ARF, and 26ARB at the four corners (front left, rear left, front right, and rear right) of the first uneven portion 20A are each included in the concept of a "first through hole" in the present disclosure.

[0054] Each of the eight (plurality of) first spot holes 27A is included in the concept of a "first through hole" in the present disclosure. As shown in Figures 2 to 3 and 13 to 14 , the eight first spot holes 27A each penetrate the first separator 2A in the up-down direction. The eight first spot holes 27A are disposed at the four corners of each of the two first manifolds 26ALM and 26ARM that are central in the front-to-rear direction among the six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB.

[0055] (Second separator 2B) The second separator 2B is a cathode (air electrode) side separator. The second separator 2B is stacked below the first separator 2A (on one side in the stacking direction). The second separator 2B is arranged symmetrically with the first separator 2A in the vertical direction. The main structural difference between the second separator 2B and the first separator 2A is that the second slits 25B are offset from the first slits 25A when viewed from the vertical direction. In addition, the second separator 2B has two relay uneven portions 200B.

[0056] 4, 5, and 7, the second separator 2B is made of metal and has a rectangular thin plate shape. The second separator 2B includes a second concave-convex portion 20B, an upper surface (inner surface in the stacking direction) 21B, a lower surface (outer surface in the stacking direction) 22B, a second opposing surface 23B, a second non-opposing surface 24B, a plurality of second slits 25B, six second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, and 26BRB, and eight second spot holes 27B.

[0057] When viewed from the top-bottom direction, the second uneven portion 20B is disposed in the center of the second separator 2B. The second uneven portion 20B has a rectangular shape. The second uneven portion 20B has a plurality of rib-shaped convex portions and a plurality of groove-shaped concave portions. The plurality of convex portions and the plurality of concave portions are arranged alternately. The second uneven portion 20B is disposed below the first uneven portion 20A. When viewed from the top-bottom direction, two relay uneven portions 200B are disposed on both the left and right sides of the second uneven portion 20B. The relay uneven portion 200B has a plurality of rib-shaped convex portions and a plurality of groove-shaped concave portions. The plurality of convex portions and the plurality of concave portions are arranged alternately.

[0058] A cooling flow path P3 is defined between a portion of the upper surface 21B corresponding to the second uneven portion 20B and a portion of the lower surface 21A of the first separator 2A corresponding to the first uneven portion 20A. Similarly, a relay flow path (not shown) is defined between a portion of the upper surface 21B corresponding to the relay uneven portion 200B and a portion of the lower surface 21A of the first separator 2A corresponding to the relay uneven portion 200B.

[0059] The second opposing surface 23B is disposed on the upper surface 21B. The upper surface 21B is included in the concept of a "second cooling surface" in the present disclosure. The second opposing surface 23B faces the first opposing surface 23A of the first separator 2A in the up-down direction.

[0060] The lower surface 22B faces away from the upper surface 21B. The lower surface 22B is included in the concept of a "second gas surface" in the present disclosure. A second gas flow path P2 (see Figures 17 to 19 described below) is defined between a portion of the lower surface 22B corresponding to the second uneven portion 20B and a portion of the power generation section 8 shown in Figure 1 that overlaps with the second uneven portion 20B. Air flows through the second gas flow path P2. Air is included in the concept of an "oxygen-containing gas" in the present disclosure.

[0061] 12, 14, and 16, the second non-opposing surface 24B is the surface of the outer surface of the second separator 2B (including the inner circumferential surfaces of second slits 25B, which will be described later, the inner circumferential surfaces of second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, and 26BRB, and the inner circumferential surfaces of second spot holes 27B) other than the second opposing surface 23B. The second non-opposing surface 24B does not face the first opposing surface 23A of the first separator 2A in the up-down direction.

[0062] Each of the multiple second slits 25B is included in the concept of a "second through hole" in the present disclosure. As shown in Figures 4 to 5 and 8 to 12, the second slits 25B penetrate the second separator 2B in the up-down direction. When viewed from the up-down direction, the second slits 25B have an elongated hole shape. The multiple second slits 25B are arranged consecutively at predetermined intervals along the rectangular outer edge of the second separator 2B.

[0063] As shown in Figures 11 and 12, the second slit 25B has two second overlapping portions 250B and a second non-overlapping portion 251B. The two second overlapping portions 250B are located at both longitudinal ends of the second slit 25B. When viewed from the top-bottom direction, the second overlapping portion 250B overlaps with the first overlapping portion 250A of the first slit 25A. The second non-overlapping portion 251B is located between the two second overlapping portions 250B. When viewed from the top-bottom direction, the second non-overlapping portion 251B does not overlap with the first overlapping portion 250A of the first slit 25A. The second non-overlapping portion 251B is covered from above by the lower surface 21A (first opposing surface 23A) of the first separator 2A.

[0064] 4 to 5 and 8 to 10, six (plural) second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, and 26BRB each penetrate the second separator 2B in the vertical direction. The six second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, and 26BRB are connected to the lower sides of the six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB.

[0065] When viewed from the top-bottom direction, the first manifold 26ALF and the second manifold 26BLF completely overlap each other. The same is true for the first manifold 26ALM and the second manifold 26BLM, the first manifold 26ALB and the second manifold 26BLB, the first manifold 26ARF and the second manifold 26BRF, the first manifold 26ARM and the second manifold 26BRM, and the first manifold 26ARB and the second manifold 26BRB. Each of the four second manifolds 26BLF, 26BLB, 26BRF, and 26BRB is included in the concept of a "second through hole" in this disclosure.

[0066] Each of the eight (plurality of) second spot holes 27B is included in the concept of "second through holes" in the present disclosure. As shown in FIGS. 4 to 5 and 13 to 14 , the eight second spot holes 27B each penetrate the second separator 2B in the up-down direction. The eight second spot holes 27B are disposed at the four corners of each of the two second manifolds 26BLM, 26BRM. When viewed from the up-down direction, the first spot holes 27A and the second spot holes 27B completely overlap each other overall.

[0067] (Slit connecting portion 30) The slit connecting portion 30 is included in the concept of "connecting portion" in the present disclosure. The slit connecting portion 30 is made of elastomer. As shown in FIGS. 3 to 4, 8, and 12, the slit connecting portion 30 fills the first slit 25A and the second slit 25B. As shown in FIG. 12, the slit connecting portion 30 is disposed across the first slit 25A and the second slit 25B. The first separator 2A and the second separator 2B are integrated via the slit connecting portion 30.

[0068] Focusing on any single first slit 25A, as viewed from the top-bottom direction, the slit connector 30 is arranged via the first slit 25A and a pair of second slits 25B on both sides of the first slit 25A in the longitudinal direction. Similarly, focusing on any single second slit 25B, as viewed from the top-bottom direction, the slit connector 30 is arranged via the second slit 25B and a pair of first slits 25A on both sides of the second slit 25B in the longitudinal direction. In this way, the slit connector 30 is arranged in a zigzag pattern, as if stitching together the multiple first slits 25A and the multiple second slits 25B.

[0069] The slit connector 30 connects any surface of the first separator 2A and any surface of the second separator 2B that do not face each other. Specifically, the slit connector 30 connects the inner circumferential surface of the first slit 25A (included in the first non-facing surface 24A) to the inner circumferential surface of the second slit 25B (included in the second non-facing surface 24B). The slit connector 30 also connects the first opposing surface 23A to the inner circumferential surface of the second slit 25B. The slit connector 30 also connects the inner circumferential surface of the first slit 25A to the second opposing surface 23B.

[0070] As shown in FIG. 1 and FIGS. 17 to 19 described below, a first gas flow path P1 is defined between the first separator 2A and the upper power generation section 8. Similarly, a second gas flow path P2 is defined between the second separator 2B and the lower power generation section 8. Furthermore, a cooling flow path P3, through which a coolant flows, is defined between the first separator 2A and the second separator 2B. As shown in FIGS. 3 and 4, when viewed from the top and bottom, the slit connecting portion 30 has an endless annular shape (rectangular frame shape) that surrounds the first concave-convex portion 20A and the second concave-convex portion 20B (first gas flow path P1, second gas flow path P2, cooling flow path P3).

[0071] (Spot hole connecting portion 31) The spot hole connecting portion 31 is included in the concept of "connecting portion" in the present disclosure. The spot hole connecting portion 31 is made of elastomer. As shown in FIGS. 3 to 4, 9, and 14, a spot hole connecting portion 31 is provided for each of the eight "first spot holes 27A and second spot holes 27B that are successively arranged in the vertical direction." In other words, a total of eight spot hole connecting portions 31 are provided. The first separator 2A and the second separator 2B are integrated via the eight spot hole connecting portions 31.

[0072] The eight spot hole connecting portions 31 have the same configuration and arrangement. Below, we will explain, as representative examples, the spot hole connecting portions 31 that are arranged at the first spot hole 27A and the second spot hole 27B (corresponding to frame XIII in FIGS. 2 to 7 and 13 ) at the rear left corners of the first manifold 26ALM and the second manifold 26BLM.

[0073] 14 , the spot hole connecting portion 31 is disposed across the first spot hole 27A and the second spot hole 27B. The spot hole connecting portion 31 fills the first spot hole 27A and the second spot hole 27B.

[0074] The spot hole connecting portion 31 connects any surface of the first separator 2A and any surface of the second separator 2B that do not face each other. Specifically, the spot hole connecting portion 31 connects the inner circumferential surface of the first spot hole 27A (included in the first non-facing surface 24A) to the inner circumferential surface of the second spot hole 27B (included in the second non-facing surface 24B).

[0075] (Manifold Connection Portion 32) The manifold connection portion 32 is included in the concept of "connection portion" in this disclosure. The manifold connection portion 32 is made of elastomer. As shown in FIGS. 3 to 4, 10, and 16, a manifold connection portion 32 is disposed between the first manifold 26ALF and the second manifold 26BLF, between the first manifold 26ALB and the second manifold 26BLB, between the first manifold 26ARF and the second manifold 26BRF, and between the first manifold 26ARB and the second manifold 26BRB. In other words, a total of four manifold connection portions 32 are disposed. The first separator 2A and the second separator 2B are integrated via the four manifold connection portions 32.

[0076] The four manifold connecting portions 32 have the same configuration and arrangement. Below, we will explain the manifold connecting portion 32 arranged in the "first manifold 26ALB and second manifold 26BLB" (corresponding to frame XV in Figures 2 to 7 and Figure 15) as a representative.

[0077] 16, the manifold connection portion 32 is disposed across the first manifold 26ALB and the second manifold 26BLB. The manifold connection portion 32 is filled in the first manifold 26ALB and the second manifold 26BLB.

[0078] The manifold connecting portion 32 connects any surface of the first separator 2A and any surface of the second separator 2B that do not face each other. Specifically, the manifold connecting portion 32 connects the inner circumferential surface of the first manifold 26ALB (included in the first non-facing surface 24A) to the inner circumferential surface of the second manifold 26BLB (included in the second non-facing surface 24B). When viewed from the top-bottom direction, the manifold connecting portion 32 has an endless annular shape (rectangular frame shape) that surrounds the first manifold 26ALB and the second manifold 26BLB.

[0079] (First slit gasket 40A) The first slit gasket 40A is included in the concept of "gasket" in the present disclosure. The first slit gasket 40A is made of elastomer. As shown in FIG. 12 , the first slit gasket 40A protrudes upward (outward in the stacking direction) from the upper surface 22A of the first separator 2A. The first slit gasket 40A is integrally connected to the slit connecting portion 30. The first slit gasket 40A is disposed above the slit connecting portion 30.

[0080] As shown in FIG. 2, when viewed from the top and bottom, the first slit gasket 40A has an endless annular (rectangular frame) shape that surrounds the first uneven portion 20A (the first gas flow path P1, the second gas flow path P2, and the cooling flow path P3).

[0081] The direction perpendicular to the extending direction of the first slit gasket 40A is defined as the lateral direction. As shown in FIG. 19 , the lateral width EAα of the first slit gasket 40A is larger than the lateral width Dα of the slit connecting portion 30.

[0082] (Second slit gasket 40B) The second slit gasket 40B is included in the concept of "gasket" in the present disclosure. The second slit gasket 40B is made of elastomer. As shown in FIG. 12 , the second slit gasket 40B protrudes downward (outward in the stacking direction) from the lower surface 22B of the second separator 2B. The second slit gasket 40B is integrally connected to the slit connecting portion 30. The second slit gasket 40B is disposed below the slit connecting portion 30.

[0083] As shown in FIG. 5, when viewed from the top and bottom, the second slit gasket 40B has an endless annular (rectangular frame) shape that surrounds the second uneven portion 20B (the first gas flow path P1, the second gas flow path P2, and the cooling flow path P3).

[0084] The direction perpendicular to the extending direction of the second slit gasket 40B is defined as the lateral direction. As shown in FIG. 19 , the lateral width EBα of the second slit gasket 40B is larger than the lateral width Dα of the slit connecting portion 30.

[0085] (First Spotting Hole Gasket 41A) The first spotting hole gasket 41A is included in the concept of "gasket" in this disclosure. The first spotting hole gasket 41A is made of elastomer. As shown in FIGS. 2, 9, and 13 to 14, the first spotting hole gaskets 41A are disposed around the first manifolds 26ALM and 26ARM. In other words, a total of two first spotting hole gaskets 41A are disposed.

[0086] The two first spot hole gaskets 41A have the same configuration and arrangement. Below, we will explain the first spot hole gasket 41A that is arranged around the first manifold 26ALM (corresponding to frame XIII in Figures 2 to 7 and Figure 13) as a representative.

[0087] 14 , the first spot hole gasket 41A protrudes upward from the upper surface 22A of the first separator 2A. The first spot hole gasket 41A is integrally connected to the spot hole connecting portion 31. The first spot hole gasket 41A is disposed above the spot hole connecting portion 31.

[0088] As shown in Fig. 2 , when viewed from the top-bottom direction, the first spot hole gasket 41A has an endless annular (rectangular frame) shape that surrounds the first manifold 26ALM. The direction perpendicular to the extension direction of the first spot hole gasket 41A is defined as the short-side direction. As shown in Fig. 14 , the short-side width EAβ of the first spot hole gasket 41A is greater than the short-side width Dβ of the spot hole connecting portion 31.

[0089] (Second Spot Hole Gasket 41B) The second spot hole gasket 41B is included in the concept of "gasket" in this disclosure. The second spot hole gasket 41B is made of elastomer. As shown in Figures 5, 9, 13 and 14, the second spot hole gaskets 41B are disposed around each of the second manifolds 26BLM, 26BRM. In other words, a total of two second spot hole gaskets 41B are disposed.

[0090] The two second spot hole gaskets 41B have the same configuration and arrangement. Below, we will explain the second spot hole gasket 41B that is arranged around the second manifold 26BLM (corresponding to frame XIII in Figures 2 to 7 and Figure 13) as a representative.

[0091] 14 , the second spot hole gasket 41B protrudes downward from the lower surface 22B of the second separator 2B. The second spot hole gasket 41B is integrally connected to the spot hole connecting portion 31. The second spot hole gasket 41B is disposed below the spot hole connecting portion 31.

[0092] As shown in Fig. 5 , when viewed from the top and bottom, the second spot hole gasket 41B has an endless annular (rectangular frame) shape that surrounds the second manifold 26BLM. The direction perpendicular to the extension direction of the second spot hole gasket 41B is defined as the short-side direction. As shown in Fig. 14 , the short-side width EBβ of the second spot hole gasket 41B is greater than the short-side width Dβ of the spot hole connecting portion 31.

[0093] (First manifold gasket 42A) The first manifold gasket 42A is included in the concept of "gasket" in this disclosure. The first manifold gasket 42A is made of elastomer. As shown in Figures 2, 10, and 15 to 16, a first manifold gasket 42A is disposed around each of the first manifolds 26ALF, 26ALB, 26ARF, and 26ARB. In other words, a total of four first manifold gaskets 42A are disposed.

[0094] The four first manifold gaskets 42A are arranged in the same manner. Of the four first manifold gaskets 42A, the two first manifold gaskets 42A arranged around each of the first manifolds 26ALF and 26ARB are configured in the same manner. Of the four first manifold gaskets 42A, the two first manifold gaskets 42A arranged around each of the first manifolds 26ALB and 26ARF are configured in the same manner. Below, we will explain the first manifold gasket 42A arranged around the first manifold 26ALB (corresponding to frame XV in Figures 2 to 7 and Figure 15) as a representative.

[0095] 16 , the first manifold gasket 42A protrudes upward (outward in the stacking direction) from the upper surface 22A of the first separator 2A. The first manifold gasket 42A is integrally connected to the manifold connecting portion 32. The first manifold gasket 42A is disposed above the manifold connecting portion 32.

[0096] As shown in Fig. 2, when viewed from the top and bottom, the first manifold gasket 42A has an endless annular shape (a rectangular frame shape) that surrounds the first manifold 26ALB. The direction perpendicular to the extension direction of the first manifold gasket 42A is defined as the lateral direction. As shown in Fig. 16, the lateral width EAγ of the first manifold gasket 42A is greater than the lateral width Dγ of the manifold connecting portion 32.

[0097] 16, the first manifold gasket 42A has a flat portion 420A and a protruding portion 421A. The flat portion 420A is continuous with the manifold connecting portion 32. The protruding portion 421A is continuous with the outer side of the flat portion 420A (outside with respect to the first manifold 26ALB). The protruding portion 421A protrudes upward from the flat portion 420A.

[0098] As shown in FIG. 2, the configuration of the first manifold gasket 42A around the first manifold 26ARF is similar to the configuration of the first manifold gasket 42A around the first manifold 26ALB described above.

[0099] Furthermore, as shown in FIG. 2, in contrast to the configuration of the first manifold gasket 42A around the first manifold 26ALB described above, the two first manifold gaskets 42A around each of the first manifolds 26ALF and 26ARB only have flat portions 420A.

[0100] (Second manifold gasket 42B) The second manifold gasket 42B is included in the concept of "gasket" in this disclosure. The second manifold gasket 42B is made of elastomer. As shown in Figures 5, 10, and 15 to 16, a second manifold gasket 42B is disposed around each of the second manifolds 26BLF, 26BLB, 26BRF, and 26BRB. In other words, a total of four second manifold gaskets 42B are disposed.

[0101] The four second manifold gaskets 42B are arranged in the same manner. Of the four second manifold gaskets 42B, the two second manifold gaskets 42B arranged around each of the second manifolds 26BLF and 26BRB are configured in the same manner. Of the four second manifold gaskets 42B, the two second manifold gaskets 42B arranged around each of the second manifolds 26BLB and 26BRF are configured in the same manner. Below, we will explain the second manifold gasket 42B arranged around the second manifold 26BLB (corresponding to frame XV in Figures 2 to 7 and Figure 15) as a representative.

[0102] 16 , the second manifold gasket 42B protrudes downward (outward in the stacking direction) from the lower surface 22B of the second separator 2B. The second manifold gasket 42B is integrally connected to the manifold connecting portion 32. The second manifold gasket 42B is disposed below the manifold connecting portion 32.

[0103] As shown in Fig. 5 , when viewed from the top and bottom, the second manifold gasket 42B has an endless annular shape (a rectangular frame shape) that surrounds the second manifold 26BLB. The direction perpendicular to the extension direction of the second manifold gasket 42B is defined as the short-side direction. As shown in Fig. 16 , the short-side width EBγ of the second manifold gasket 42B is greater than the short-side width Dγ of the manifold connecting portion 32.

[0104] As shown in Fig. 16, the second manifold gasket 42B has a flat portion 420B. The flat portion 420B is continuous with the manifold connecting portion 32. Note that, as shown in Fig. 5, the configuration of the second manifold gasket 42B around the second manifold 26BRF is similar to the configuration of the second manifold gasket 42B around the second manifold 26BLB described above.

[0105] 5, in contrast to the configuration of the second manifold gasket 42B around the second manifold 26BLB described above, the two second manifold gaskets 42B around the second manifold 26BLF and the second manifold 26BRB each include a flat portion 420B and a protruding portion 421B. The protruding portion 421B has a configuration similar to the protruding portion 421A shown in FIG. 16. The protruding portion 421B is continuous with the outer side of the flat portion 420B (outside with respect to the second manifolds 26BLF and 26BRB). The protruding portion 421B protrudes upward relative to the flat portion 420B.

[0106] [Method for Manufacturing Bipolar Plate] Next, a method for manufacturing the bipolar plate of this embodiment will be described. The method for manufacturing the bipolar plate of this embodiment includes an injection step and a vulcanization step (crosslinking step).

[0107] Fig. 17 shows a vertical partial cross-sectional view of the mold used to manufacture the bipolar plate of this embodiment in an open state. Fig. 18 shows a vertical partial cross-sectional view of the mold in a closed state (at the beginning of the injection process). Fig. 19 shows a vertical partial cross-sectional view of the mold in a closed state (at the end of the vulcanization process). The portion of the bipolar plate 1 shown in Figs. 17 to 19 corresponds to the XVII-XVII cross section in Fig. 11.

[0108] As shown in Figure 17, the mold 5 includes a first mold (movable mold) 5A and a second mold (fixed mold) 5B. The mold 5 is included in the concept of a "molding mold" in the present disclosure. The first mold 5A can be attached to and detached from the second mold 5B from above. A first gasket-molding recess 50A is recessed in the bottom surface of the first mold 5A. A second gasket-molding recess 50B and a separator-receiving recess 51B are recessed in the top surface of the second mold 5B. The second gasket-molding recess 50B is recessed in the bottom surface of the separator-receiving recess 51B. The first gasket-molding recess 50A and the second gasket-molding recess 50B are included in the concept of a "gasket-molding recess" in the present disclosure.

[0109] Six manifold insertion protrusions (not shown) protrude from the bottom surface of the separator accommodating recess 51B. The positions of the six manifold insertion protrusions correspond to the positions of the six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB shown in Fig. 2 and the positions of the six second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, and 26BRB shown in Fig. 5. The six manifold insertion protrusions are inserted into the six first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB and the six second manifolds 26BLF, 26BLM, 26BLB, 26BRF, and 26BRM.

[0110] Gaps for molding the manifold connecting portions 32 are defined between the inner circumferential surfaces of the four first manifolds 26ALF, 26ALB, 26ARF, and 26ARB and the four second manifolds 26BLF, 26BLB, 26BRF, and 26BRB shown in Figures 3 and 4 and the manifold insertion protrusions described above.

[0111] 17 to 19 , the first gasket-molding recess 50A and the second gasket-molding recess 50B face each other in the vertical direction, sandwiching the separator-accommodating recess 51B therebetween. The shape and arrangement of the first gasket-molding recess 50A correspond to the shape and arrangement of the gaskets (first slit gasket 40A, two first spot hole gaskets 41A, and four first manifold gaskets 42A) molded in the first separator 2A. Similarly, the shape and arrangement of the second gasket-molding recess 50B correspond to the shape and arrangement of the gaskets (second slit gasket 40B, two second spot hole gaskets 41B, and four second manifold gaskets 42B) molded in the second separator 2B.

[0112] 17 , in this step, the first separator 2A and the second separator 2B in a stacked state are placed in the separator accommodating recess 51B of the second mold 5B of the mold 5 in an open state. In the stacked state, the first through-holes (plurality of first slits 25A, four first manifolds 26ALF, 26ALB, 26ARF, 26ARB, and eight first spot holes 27A) of the first separator 2A and the second through-holes (plurality of second slits 25B, four second manifolds 26BLF, 26BLB, 26BRF, and 26BRB, and eight second spot holes 27B) of the second separator 2B are in communication with each other.

[0113] An adhesive (not shown) is applied to the first separator 2A and the second separator 2B in advance. Specifically, the adhesive is applied to the outer surface of the first separator 2A (including the inner peripheral surface of the first slit 25A, the inner peripheral surfaces of the first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, and 26ARB, and the inner peripheral surface of the first spotting hole 27A) and the outer surface of the second separator 2B (including the inner peripheral surface of the second slit 25B, the inner peripheral surfaces of the second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, and 26BRB, and the inner peripheral surface of the second spotting hole 27B). Among the four manifold gaskets (including the eight manifold gaskets 42A and 42B), adhesive (not shown) has been applied in advance to the portions where the connecting portions (slit connecting portion 30, eight spot hole connecting portions 31, and four manifold connecting portions 32) and gaskets (first slit gasket 40A, second slit gasket 40B, two first spot hole gaskets 41A, two second spot hole gaskets 41B, four first manifold gaskets 42A, and four second manifold gaskets 42B) are to be arranged.

[0114] Next, as shown in Figure 18, the first mold 5A is pressed against the second mold 5B with a predetermined mold clamping force. That is, the mold is clamped. By clamping the mold, the first gasket-molding recess 50A and the second gasket-molding recess 50B are communicated with each other via the first through-hole in the first separator 2A and the second through-hole in the second separator 2B. Then, raw materials (raw materials for the gasket and connecting portion) are injected and filled into the first gasket-molding recess 50A, the second gasket-molding recess 50B, the first through-hole, and the second through-hole.

[0115] 19 , the mold 5 in a clamped state is heated at a predetermined temperature for a predetermined time to harden the raw material. That is, gaskets (first slit gasket 40A, second slit gasket 40B, two first spot hole gaskets 41A, two second spot hole gaskets 41B, four first manifold gaskets 42A, and four second manifold gaskets 42B) are molded. In addition, connecting portions (slit connecting portions 30, eight spot hole connecting portions 31, and four manifold connecting portions 32) are molded.

[0116] As described above, the adhesive is applied to the first separator 2A and the second separator 2B in advance, so that the gasket and the connecting portion are bonded to the first separator 2A and the second separator 2B simultaneously with molding.

[0117] As described above, in the method for manufacturing a bipolar plate according to this embodiment, the joining operation of the first separator 2A and the second separator 2B and the production operation of the gasket are carried out in parallel.

[0118] [Effects] Next, the effects of the bipolar plate and its manufacturing method according to this embodiment will be described. As shown in FIG. 12 , the slit connector 30 connects the inner circumferential surface of the first slit 25A (included in the first non-opposing surface 24A) to the inner circumferential surface of the second slit 25B (included in the second non-opposing surface 24B). The slit connector 30 also connects the first opposing surface 23A to the inner circumferential surface of the second slit 25B. The slit connector 30 also connects the inner circumferential surface of the first slit 25A to the second opposing surface 23B. That is, the slit connector 30 connects any surface of the first separator 2A and any surface of the second separator 2B that do not face each other.

[0119] 14 , spot hole connecting portion 31 connects the inner circumferential surface of first spot hole 27A (included in first non-opposing surface 24A) to the inner circumferential surface of second spot hole 27B (included in second non-opposing surface 24B). In other words, spot hole connecting portion 31 connects any surfaces of first separator 2A and any surfaces of second separator 2B that do not face each other.

[0120] 16 , the manifold connecting portion 32 connects the inner circumferential surface of the first manifold 26ALB (included in the first non-opposing surface 24A) to the inner circumferential surface of the second manifold 26BLB (included in the second non-opposing surface 24B). In other words, the manifold connecting portion 32 connects any surfaces of the first separator 2A and any surfaces of the second separator 2B that do not face each other.

[0121] 12, 14, and 16 (slit connecting portion 30, spot hole connecting portion 31, manifold connecting portion 32) each connects any surface of the first separator 2A and any surface of the second separator 2B that do not face each other. Therefore, at least one of the multiple connecting portions can reduce the burden of managing the pressing accuracy between the first separator 2A and the second separator 2B. This makes it easier to join (combine or integrate) the first separator 2A and the second separator 2B.

[0122] 12, 14, and 16 are each made of an elastomer and have elasticity (rubber elasticity). Therefore, even if springback occurs in the first separator 2A or the second separator 2B during bonding, at least a portion of the springback can be absorbed by the elastic deformation of at least one of the multiple connecting parts.

[0123] Each of the multiple connecting portions shown in Figures 12, 14, and 16 connects surfaces in at least one combination of "(A) the first non-opposing surface 24A and the second non-opposing surface 24B," "(B) the first opposing surface 23A and the second non-opposing surface 24B," and "(C) the first non-opposing surface 24A and the second opposing surface 23B," i.e., connects surfaces in a combination other than "the first opposing surface 23A and the second opposing surface 23B." This reduces the burden of managing the pressing accuracy between the first separator 2A and the second separator 2B. This also facilitates the joining process between the first separator 2A and the second separator 2B.

[0124] 11 and 12 , when viewed from the top-bottom direction, the first slit 25A and the second slit 25B partially overlap each other due to a first overlapping portion 250A and a second overlapping portion 250B. The slit connecting portion 30 is disposed across the first slit 25A and the second slit 25B. Therefore, the slit connecting portion 30 can integrate the first separator 2A and the second separator 2B by utilizing the space within the hole of the first slit 25A and the space within the hole of the second slit 25B.

[0125] 13 and 14 , the first spot hole 27A and the second spot hole 27B completely (entirely) overlap each other when viewed from the top-bottom direction. The spot hole connecting portion 31 is disposed across the first spot hole 27A and the second spot hole 27B. Therefore, the spot hole connecting portion 31 can integrate the first separator 2A and the second separator 2B by utilizing the space within the first spot hole 27A and the space within the second spot hole 27B.

[0126] 15 and 16 , the first manifold 26ALB and the second manifold 26BLB completely (entirely) overlap each other when viewed from the top-bottom direction. The manifold connection portion 32 is disposed across the first manifold 26ALB and the second manifold 26BLB. Therefore, the manifold connection portion 32 can integrate the first separator 2A and the second separator 2B by utilizing the space within the holes of the first manifold 26ALB and the space within the holes of the second manifold 26BLB. The same applies to the first manifold 26ALF and the second manifold 26BLF, the first manifold 26ARF and the second manifold 26BRF, and the first manifold 26ARB and the second manifold 26BRB.

[0127] 11 and 12, the first slit 25A and the second slit 25B partially overlap each other. Merged portions 250CL and 250CR of the first overlapping portion 250A and the second overlapping portion 250B penetrate the first separator 2A and the second separator 2B in the up-down direction.

[0128] 12 , the first overlapping portion 250A at the left end (one longitudinal end) of the first slit 25A and the second overlapping portion 250B at the right end (the other longitudinal end) of the second slit 25B on the left side of the first slit 25A form a junction 250CL. Starting from the junction 250CL, the first non-overlapping portion 251A extends to the right (the other longitudinal end). Meanwhile, the second non-overlapping portion 251B extends to the left (one longitudinal end). Thus, the first non-overlapping portion 251A and the second non-overlapping portion 251B extend in different directions. Therefore, the slit connecting portion 30 can be deployed in the left-right direction (the plane direction of the bipolar plate 1, perpendicular to the stacking direction) along the first non-overlapping portion 251A and the second non-overlapping portion 251B.

[0129] As shown in FIG. 12 , any single first slit 25A has a pair of left and right first overlapping portions 250A. A pair of left and right second slits 25B are connected to the lower side of the first slit 25A. The first overlapping portion 250A at the left end of the first slit 25A is connected to the second overlapping portion 250B at the right end of the left-side second slit 25B. The first overlapping portion 250A at the right end of the first slit 25A is connected to the second overlapping portion 250B at the left end of the right-side second slit 25B. In this way, the multiple first overlapping portions 250A of the first slit 25A are each connected to a different second slit 25B. The slit connecting portion 30 is arranged via the first slit 25A and the multiple second slits 25B. Therefore, as shown in FIG. 8 , the first separator 2A and the second separator 2B can be joined as if sewn together.

[0130] Similarly, the multiple second overlapping portions 250B of any single second slit 25B each communicate with a different first slit 25A. The slit connecting portion 30 is disposed via the second slit 25B and the multiple first slits 25A. Therefore, as shown in FIG. 8 , the second separator 2B and the first separator 2A can be joined together as if they were sewn together.

[0131] 12 , the slit connectors 30 fill the first slits 25A and the second slits 25B. This allows for a larger volume of material in the slit connectors 30 than when the first slits 25A and the second slits 25B are not filled with the slit connectors 30. The slit connectors 30 are also bonded over the entire inner circumferential surfaces of the first slits 25A and the second slits 25B. This allows for a secure bond between the first separator 2A and the second separator 2B.

[0132] 12, the first slits 25A and the second slits 25B are connected without any gaps in the vertical direction, which allows the vertical thickness of the bipolar plate 1 to be smaller than when there is a gap between the first slits 25A and the second slits 25B and the slit connecting portion 30 is inserted in the gap.

[0133] 14, the first spot hole 27A and the second spot hole 27B are connected in the vertical direction without any gap between them, which allows the vertical thickness of the bipolar plate 1 to be smaller than when there is a gap between the first spot hole 27A and the second spot hole 27B and the part of the spot hole connecting portion 31 is interposed in the gap.

[0134] 16, the first manifold 26ALB and the second manifold 26BLB are connected without any gaps in the vertical direction. Therefore, the vertical thickness of the bipolar plate 1 can be reduced compared to when there is a gap between the first manifold 26ALB and the second manifold 26BLB and the manifold connecting portion 32 is interposed in the gap. The same applies to the first manifold 26ALF and the second manifold 26BLF, the first manifold 26ARF and the second manifold 26BRF, and the first manifold 26ARB and the second manifold 26BRB.

[0135] As shown in FIG. 19 , a first gas flow path P1, a second gas flow path P2, and a cooling flow path P3 are defined between the first concave-convex portion 20A of the first separator 2A and the second concave-convex portion 20B of the second separator 2B. As shown in FIGS. 3 , 4 , and 8 , when viewed from the top and bottom, the slit connector 30 has an endless annular shape that surrounds the first concave-convex portion 20A and the second concave-convex portion 20B (i.e., the first gas flow path P1, the second gas flow path P2, and the cooling flow path P3). Therefore, the first separator 2A and the second separator 2B are joined via the slit connector 30, and the endless annular slit connector 30 can seal the first gas flow path P1, the second gas flow path P2, and the cooling flow path P3. In other words, the joining operation of the first separator 2A and the second separator 2B and the sealing operation of the first gas flow path P1, the second gas flow path P2, and the cooling flow path P3 can be performed in parallel. Therefore, compared to when the joining operation and the sealing operation are performed separately, the manufacturing time of the bipolar plate 1 can be shortened and the number of manufacturing steps can be reduced.

[0136] 3, 4, and 10, when viewed from above and below, the manifold connecting portion 32 has an endless annular shape that surrounds the first manifold 26ALB and the second manifold 26BLB. Therefore, the first separator 2A and the second separator 2B are joined via the manifold connecting portion 32, and the endless annular manifold connecting portion 32 can seal the first manifold 26ALB and the second manifold 26BLB (specifically, the gas flow paths inside these manifolds). That is, the joining operation of the first separator 2A and the second separator 2B and the sealing operation of the gas flow paths inside the manifolds can be performed in parallel. Therefore, compared to when the joining operation and the sealing operation are performed separately, the manufacturing time of the bipolar plate 1 can be shortened, and the manufacturing steps can be reduced. The same applies to the first manifold 26ALF and the second manifold 26BLF, the first manifold 26ARF and the second manifold 26BRF, and the first manifold 26ARB and the second manifold 26BRB.

[0137] As shown in FIG. 12 , the first slit gasket 40A and the second slit gasket 40B protrude from both the upper surface 22A and the lower surface 22B of the slit connecting portion 30 in the vertical direction. The first slit gasket 40A and the second slit gasket 40B are integrally connected to the slit connecting portion 30. This allows the first separator 2A and the second separator 2B to be joined via the slit connecting portion 30, and the first slit gasket 40A and the second slit gasket 40B to be fabricated from the slit connecting portion 30. That is, the joining operation of the first separator 2A and the second separator 2B and the fabrication operation of the first slit gasket 40A and the second slit gasket 40B can be performed in parallel. This shortens the manufacturing time and reduces the number of manufacturing steps for the bipolar plate 1 compared to when the joining operation and the fabrication operation are performed separately.

[0138] As shown in FIG. 14 , the first spot hole gasket 41A and the second spot hole gasket 41B protrude from both the upper surface 22A and the lower surface 22B of the spot hole connecting portion 31 in the vertical direction. The first spot hole gasket 41A and the second spot hole gasket 41B are integrally connected to the spot hole connecting portion 31. This allows the first separator 2A and the second separator 2B to be joined via the spot hole connecting portion 31, and the first spot hole gasket 41A and the second spot hole gasket 41B to be fabricated from the spot hole connecting portion 31. That is, the joining operation of the first separator 2A and the second separator 2B and the fabrication operation of the first spot hole gasket 41A and the second spot hole gasket 41B can be performed in parallel. This shortens the manufacturing time and reduces the number of manufacturing steps for the bipolar plate 1 compared to when the joining operation and the fabrication operation are performed separately.

[0139] 16 , the first manifold gasket 42A and the second manifold gasket 42B protrude upward and downward from the manifold connecting portion 32 (i.e., from the upper surface 22A and the lower surface 22B). The first manifold gasket 42A and the second manifold gasket 42B are integrally connected to the manifold connecting portion 32. This allows the first separator 2A and the second separator 2B to be joined via the manifold connecting portion 32, and the first manifold gasket 42A and the second manifold gasket 42B to be fabricated from the manifold connecting portion 32. In other words, the joining operation of the first separator 2A and the second separator 2B and the fabrication operation of the first manifold gasket 42A and the second manifold gasket 42B can be performed in parallel. This shortens the manufacturing time of the bipolar plate 1 and reduces the number of manufacturing steps compared to when the joining operation and the fabrication operation are performed separately.

[0140] As shown in FIG. 19 , focusing on the width in the short side direction (front-rear direction, perpendicular to the left-right direction (extending direction of the first slit gasket 40A)), the short side width EAα of the first slit gasket 40A is larger than the short side width Dα of the slit connecting portion 30. This makes it possible to prevent fuel gas from leaking across the first slit gasket 40A from the first gas flow path P1 to the outside. In other words, the sealing performance of the first slit gasket 40A can be improved. Furthermore, because the relationship "short side width EAα > short side width Dα" holds, it is possible to prevent the first slit gasket 40A from sinking into the first slit 25A. This makes it possible to prevent separation between the first separator 2A and the second separator 2B.

[0141] Similarly, the second slit gasket 40B also satisfies the relationship "width EBα in the short side direction > width Dα in the short side direction." Therefore, the second slit gasket 40B has the same effect as the first slit gasket 40A.

[0142] As shown in FIG. 14 , when focusing on the width in the short side direction (right-front-left-rear direction; a direction perpendicular to the left-front-right-rear direction (the extension direction of the first spot hole gasket 41A)), the short side width EAβ of the first spot hole gasket 41A is larger than the short side width Dβ of the spot hole connecting portion 31. This improves the sealing performance of the first spot hole gasket 41A. Furthermore, because the relationship "short side width EAβ > short side width Dβ" holds, it is possible to prevent the first spot hole gasket 41A from sinking into the first spot hole 27A. This makes it possible to prevent separation between the first separator 2A and the second separator 2B.

[0143] Similarly, the second spot hole gasket 41B also satisfies the relationship "width EBβ>width Dβ." Therefore, the second spot hole gasket 41B has the same effect as the first spot hole gasket 41A.

[0144] As shown in FIG. 16 , when focusing on the width in the short side direction (left-right direction; a direction perpendicular to the front-rear direction (the extension direction of the first manifold gasket 42A)), the short side width EAγ of the first manifold gasket 42A is larger than the short side width Dγ of the manifold connecting portion 32. This improves the sealing performance of the first manifold gasket 42A. Furthermore, because the relationship "short side width EAγ > short side width Dγ" holds and the first manifold gasket 42A protrudes radially outward from the opening edge of the first manifold 26ALB, it is possible to prevent the first manifold gasket 42A from sinking into the first manifold 26ALB. This makes it possible to prevent separation between the first separator 2A and the second separator 2B.

[0145] Similarly, the second manifold gasket 42B also has the relationship "short-side width EBγ > short-side width Dγ." Furthermore, the second manifold gasket 42B protrudes radially outward from the opening edge of the second manifold 26BLB. Therefore, the second manifold gasket 42B has the same effect as the first manifold gasket 42A.

[0146] 12 , when focusing on the vertical cross section of the bipolar plate 1 (a cross section in the direction in which the first slits 25A and the second slits 25B extend), the non-through hole portion of the second separator 2B (the portion overlapping with the first non-overlapping portion 251A when viewed from the vertical direction) is completely surrounded by material (the material of the slit connecting portion 30 and the material of the second slit gasket 40B). This prevents the first separator 2A and the second separator 2B from separating. The same is true for the non-through hole portion of the first separator 2A (the portion overlapping with the second non-overlapping portion 251B when viewed from the vertical direction).

[0147] 17 to 19, according to the manufacturing method of the bipolar plate 1 of this embodiment, connecting portions (slit connecting portions 30, spot hole connecting portions 31, manifold connecting portions 32) are formed in the hole spaces of the first through-holes (first slits 25A, first manifolds 26ALF, 26ALB, 26ARF, 26ARB, first spot holes 27A) and the hole spaces of the second through-holes (second slits 25B, second manifolds 26BLF, 26BLB, 26BRF, 26BRB, second spot holes 27B), as shown in FIGS. 12, 14, and 16. These connecting portions enable the first separator 2A and the second separator 2B to be integrated together.

[0148] As shown in Figures 18 and 19, in the mold-clamped state, the first gasket-molding recess 50A and the second gasket-molding recess 50B are connected to the first through-hole and the second through-hole. Therefore, by injecting raw materials (gasket and connecting portion raw materials) into the mold 5 in the injection process and curing them, the gaskets (the first slit gasket 40A, the second slit gasket 40B, the first spot-hole gasket 41A, the second spot-hole gasket 41B, the first manifold gasket 42A, and the four second manifold gaskets 42B) can be molded together with the connecting portions. In other words, the joining operation of the first separator 2A and the second separator 2B and the gasket fabrication operation can be performed in parallel. Therefore, compared to performing the joining operation and the fabrication operation separately, the manufacturing time and the number of manufacturing steps for the bipolar plate 1 can be shortened.

[0149] Second Embodiment The bipolar plate and its manufacturing method of the second embodiment differ from the bipolar plate and its manufacturing method of the first embodiment in that a gasket separate from the connecting portion is provided. Only this difference will be described here.

[0150] Figure 20 shows a partial cross-sectional view of the bipolar plate of this embodiment taken in the vertical direction. The same reference numerals are used to denote portions corresponding to those in Figure 14. As shown in Figure 20, the first spot hole gasket 41A and the second spot hole gasket 41B are separate from the spot hole connecting portion 31. The first spot hole gasket 41A and the second spot hole gasket 41B are each joined to the spot hole connecting portion 31.

[0151] The bipolar plate and manufacturing method thereof of this embodiment and the bipolar plate and manufacturing method thereof of the first embodiment have similar effects with respect to common configurations. In the bipolar plate of this embodiment, the connecting portion (spot hole connecting portion 31) and the gaskets (first spot hole gasket 41A, second spot hole gasket 41B) are separate bodies. This allows for greater design freedom (freedom of selection of shape, size, material, etc.) for the connecting portion and the gaskets compared to when the connecting portion and the gaskets are integrally connected.

[0152] The first spotting hole gasket 41A or the second spotting hole gasket 41B may be integrally connected to the spotting hole connecting portion 31. The material of the first spotting hole gasket 41A and the material of the second spotting hole gasket 41B may be the same as or different from each other.

[0153] Third Embodiment The bipolar plate and its manufacturing method of this embodiment differ from the bipolar plate and its manufacturing method of the first embodiment in that the width of the gasket in the lateral direction is the same as the width of the connecting portion in the lateral direction. Here, only the difference will be described.

[0154] Figure 21 shows a partial cross-sectional view of the bipolar plate of this embodiment taken in the vertical direction. The same reference numerals are used to denote portions corresponding to those in Figure 14. As shown in Figure 21, the width EAβ of the first spot hole gasket 41A in the short-side direction is the same as the width Dβ of the spot hole connecting portion 31. Similarly, the width EBβ of the second spot hole gasket 41B in the short-side direction is the same as the width Dβ of the spot hole connecting portion 31.

[0155] The bipolar plate and manufacturing method thereof of this embodiment and the bipolar plate and manufacturing method thereof of the first embodiment have the same effects as those of the first embodiment, except that the bipolar plate and manufacturing method thereof may have the same relationship of "transverse width EAβ≦transverse width Dβ" or "transverse width EBβ≦transverse width Dβ" as in the bipolar plate of this embodiment.

[0156] <Others> The embodiments of the bipolar plate of the present disclosure have been described above. However, the embodiments are not particularly limited to the above-described embodiments. Various modifications and improvements that can be made by those skilled in the art are also possible.

[0157] The shape and the like (shape, size, position, arrangement number, etc.) of the first uneven portion 20A are not particularly limited. The same applies to the first slits 25A, first manifolds 26ALF, 26ALM, 26ALB, 26ARF, 26ARM, 26ARB, first spot holes 27A, second uneven portion 20B, second slits 25B, second manifolds 26BLF, 26BLM, 26BLB, 26BRF, 26BRM, 26BRB, second spot holes 27B, gaskets (first slit gasket 40A, second slit gasket 40B, two first spot hole gaskets 41A, two second spot hole gaskets 41B, four first manifold gaskets 42A, four second manifold gaskets 42B), and connecting portions (slit connecting portion 30, eight spot hole connecting portions 31, four manifold connecting portions 32).

[0158] When the gasket and the connecting portion are integral, the boundary between the gasket and the connecting portion is not particularly limited. For example, when viewed from the surface direction (the direction perpendicular to the stacking direction), the portions disposed outside the first separator 2A and the second separator 2B (outside the stacking direction) may be the gaskets, and the other portions (portions disposed inside the first separator 2A and the second separator 2B (inside the stacking direction)) may be the connecting portions.

[0159] The shape in the extension direction of the gaskets shown in Figures 2 and 5 may be strip-shaped (straight, curved, or a suitable combination of these shapes), block-shaped (circular, elliptical, droplet-shaped, polygonal (triangular, rectangular, hexagonal, or the like), irregular, or frame-shaped (circular, elliptical, or polygonal). The shape in the transverse direction of the gaskets shown in Figures 14, 16, and 19 may be rectangular, trapezoidal, arc-shaped, V-shaped, C-shaped, U-shaped, or a suitable combination of these shapes.

[0160] The bipolar plate 1 may include a first gasket (first slit gasket 40A, first spot hole gasket 41A, first manifold gasket 42A) and a second gasket (second slit gasket 40B, second spot hole gasket 41B, second manifold gasket 42B). The bipolar plate 1 may include only the first gasket. The bipolar plate 1 may include only the second gasket. The bipolar plate 1 may not include the first gasket or the second gasket.

[0161] The extension directions of the first non-overlapping portion 251A and the second non-overlapping portion 251B starting from the combined portion 250CL shown in FIG. 12 are not particularly limited. The first non-overlapping portion 251A and the second non-overlapping portion 251B may extend in different directions. For example, the first non-overlapping portion 251A and the second non-overlapping portion 251B may extend in 180° opposite directions (e.g., forward and backward, left and right). The first non-overlapping portion 251A and the second non-overlapping portion 251B may also extend in 90° opposite directions (e.g., forward and left, forward and backward). Of course, the crossing angle (included angle) between the extension direction of the first non-overlapping portion 251A and the extension direction of the second non-overlapping portion 251B when viewed from the top-bottom direction is not particularly limited. The crossing angle may be, for example, 30°, 45°, 60°, 90°, 120°, 135°, 150°, 180°, etc. Furthermore, the first non-overlapping portion 251A and the second non-overlapping portion 251B may extend in the same direction (for example, forward and forward, or left and left).

[0162] The opening and closing direction of the mold 5 shown in Figures 17 to 19 is not particularly limited. It may be a vertical direction, a horizontal direction, or a direction intersecting the vertical and horizontal directions. In the injection step, the first mold 5A may be a fixed mold and the second mold 5B may be a movable mold. Conversely, the first mold 5A may be a movable mold and the second mold 5B may be a fixed mold.

[0163] The material of the first separator 2A and the second separator 2B is not particularly limited. It may be a resin, metal, carbon, or other material that is conductive and non-corrosive. Examples include stainless steel, titanium, copper, magnesium, aluminum, carbon, graphite, ceramics, and conductive resins (thermoplastic or thermosetting resins containing carbon, graphite, polyacrylonitrile-based carbon fiber, etc.).

[0164] The materials for the connecting portion and the gasket are not particularly limited. They are sufficient as long as they are elastomers that have insulating properties and elasticity after curing. They are sufficient as long as they have fluidity in the raw material stage (before curing). The connecting portion and the gasket may contain, in addition to the rubber component, a crosslinking agent, a co-crosslinking agent, a processing aid, a softener, a reinforcing material, etc. Suitable rubber components include VMQ (silicone rubber), silicone rubbers other than VMQ (such as PVMQ (phenyl vinyl methyl silicone rubber) and FVMQ (fluoro vinyl methyl silicone rubber)), EPDM (ethylene propylene diene rubber), and FKM (fluoro rubber). When liquid silicone rubber is used as the raw material, the type of liquid silicone rubber is not particularly limited. They may be one-component or two-component. They may also be room temperature curing or heat curing.

[0165] When the connecting portion and at least one of the first gasket and the second gasket are separate from each other, the material of the connecting portion and the material of the gasket (first gasket, second gasket) separate from the connecting portion may be the same or different. Also, the material of the first gasket and the material of the second gasket may be the same or different.

[0166] The material of the mold 5 is not particularly limited, and may be corrosion-resistant steel, carbon tool steel, alloy tool steel, high-speed tool steel, as-rolled steel, pre-hardened steel, quenched steel, quenched and tempered steel, aging-treated steel, or the like.

[0167] 1: Bipolar plate 2A: First separator, 20A: First uneven portion, 21A: Lower surface (first cooling surface), 22A: Upper surface (first gas surface), 23A: First opposing surface, 24A: First non-opposing surface, 25A: First slit (first through hole), 250A: First overlapping portion, 251A: First non-overlapping portion, 26ALF: First manifold (first through hole), 26ALM: First manifold, 26ALB: First manifold (first through hole), 26ARF: First manifold (first through hole), 26ARM: First manifold, 26ARB: First manifold (first through hole), 27A: First spot hole (first through hole) 2B: second separator, 20B: second uneven portion, 200B: relay uneven portion, 21B: upper surface (second cooling surface), 22B: lower surface (second gas surface), 23B: second opposing surface, 24B: second non-opposing surface, 25B: second slit (second through hole), 250B: second overlapping portion, 251B: second non-overlapping portion, 26BLF: second manifold (second through hole), 26BLM: second manifold, 26BLB: second manifold (second through hole), 26BRF: second manifold (second through hole), 26BRM: second manifold, 26BRB: second manifold (second through hole), 27B: second spot hole (second through hole), 250CL: joining portion, 250CR: joining portion, 30: slit connecting portion (connecting portion), 31: spot hole connecting portion (connecting portion), 32: manifold connecting portion (connecting portion) 40A: first slit gasket (gasket), 41A: first spot hole gasket (gasket), 42A: first manifold gasket (gasket), 420A: flat portion, 421A: protruding portion 40B: second slit gasket (gasket), 41B: second spot hole gasket (gasket), 42B: second manifold gasket (gasket), 420B: flat portion, 421B: protruding portion 5: mold (forming die), 5A: first mold, 50A: first gasket-forming recess (gasket-forming recess), 5B: second mold, 50B: second gasket-forming recess (gasket-forming recess), 51B: separator-accommodating recess 8: power generation portion, 80: membrane electrode assembly, 800: electrolyte membrane, 801: electrode, 81: gas diffusion layer 9: stack P1: first gas flow path, P2: second gas flow path, P3: cooling flow path

Claims

1. A bipolar plate for a fuel cell comprising: a first separator; a second separator laminated on the first separator; and an elastomer connecting portion connecting any surface of the first separator and any surface of the second separator that do not face each other.

2. A bipolar plate as described in claim 1, wherein the direction in which the first separator and the second separator are stacked is defined as a stacking direction, the first separator has a first through hole passing through it in the stacking direction, the second separator has a second through hole passing through it in the stacking direction, the first through hole and the second through hole overlap each other in whole or in part as viewed from the stacking direction, the connecting portion is arranged across the first through hole and the second through hole, and the first separator and the second separator are integrated via the connecting portion.

3. A bipolar plate as described in claim 2, wherein the first through hole has, when viewed from the stacking direction, a first overlapping portion that overlaps with the second through hole and a first non-overlapping portion that does not overlap with the second through hole, and the second through hole has, when viewed from the stacking direction, a second overlapping portion that overlaps with the first through hole and a second non-overlapping portion that does not overlap with the first through hole, and the first non-overlapping portion and the second non-overlapping portion extend in different directions from each other.

4. A bipolar plate according to claim 3, wherein the first through hole has a plurality of the first overlapping portions, the second through hole is arranged in a plurality of portions, the plurality of first overlapping portions each communicate with a different second through hole, and the connecting portion is arranged via the first through hole and the plurality of second through holes.

5. A bipolar plate according to claim 3, wherein the second through hole has a plurality of the second overlapping portions, the first through holes are arranged in a plurality, the plurality of second overlapping portions each communicate with a different one of the first through holes, and the connecting portion is arranged via the second through hole and the plurality of first through holes.

6. The bipolar plate according to claim 2, wherein the connecting portion is filled in at least one of the first through-holes and the second through-holes.

7. A bipolar plate as described in claim 2, wherein the first separator has a first opposing surface facing the second separator in the stacking direction and a first non-opposing surface not facing the second separator in the stacking direction, the second separator has a second opposing surface facing the first separator in the stacking direction and a second non-opposing surface not facing the first separator in the stacking direction, the inner circumferential surface of the first through hole is included in the first non-opposing surface, and the connecting portion housed in the first through hole connects the inner circumferential surface of the first through hole to the second opposing surface.

8. A bipolar plate as described in claim 2, wherein the first separator has a first opposing surface facing the second separator in the stacking direction and a first non-opposing surface not facing the second separator in the stacking direction, the second separator has a second opposing surface facing the first separator in the stacking direction and a second non-opposing surface not facing the first separator in the stacking direction, the inner circumferential surface of the second through hole is included in the second non-opposing surface, and the connecting portion housed in the second through hole connects the inner circumferential surface of the second through hole to the first opposing surface.

9. The bipolar plate according to claim 2, wherein the first through holes and the second through holes are continuous with each other without any gaps in the stacking direction.

10. A bipolar plate as described in claim 1, wherein the direction in which the first separator and the second separator are stacked is the stacking direction, a cooling flow path through which a coolant flows is defined between the first separator and the second separator, and when viewed from the stacking direction, the connecting portion presents an endless ring shape surrounding the cooling flow path.

11. A bipolar plate as described in claim 1, wherein the direction in which the first separator and the second separator are stacked is the stacking direction, a cooling flow path through which a coolant flows is defined between the first separator and the second separator, the first separator has a first cooling surface which is the surface on the cooling flow path side and a first gas surface which faces away from the first cooling surface, the second separator has a second cooling surface which is the surface on the cooling flow path side and a second gas surface which faces away from the second cooling surface, and further comprising a gasket which protrudes outward in the stacking direction from at least one of the first gas surface and the second gas surface and is integrally connected to the connecting portion.

12. A bipolar plate as described in claim 1, wherein the direction in which the first separator and the second separator are stacked is the stacking direction, a cooling flow path through which a coolant flows is defined between the first separator and the second separator, the first separator has a first cooling surface which is the surface on the cooling flow path side and a first gas surface which faces away from the first cooling surface, the second separator has a second cooling surface which is the surface on the cooling flow path side and a second gas surface which faces away from the second cooling surface, and further comprising a gasket which protrudes outward in the stacking direction from at least one of the first gas surface and the second gas surface and is separate from the connecting portion.

13. A bipolar plate as described in claim 11 or claim 12, wherein a power generation section of a fuel cell is arranged on both outer sides of the first separator and the second separator in the stacking direction, the gasket protrudes from the first gas surface and the second gas surface on both outer sides in the stacking direction, a first gas flow path through which one of a hydrogen-containing gas and an oxygen-containing gas flows is defined between the first separator and the power generation section, and a second gas flow path through which the other of the hydrogen-containing gas and the oxygen-containing gas flows is defined between the second separator and the power generation section, and the gasket has an endless ring shape surrounding the first gas flow path and the second gas flow path when viewed in the stacking direction.

14. A bipolar plate according to claim 13, wherein a direction perpendicular to the extension direction of the gasket on the first gas surface and the second gas surface is defined as a short-side direction, and the width of the gasket in the short-side direction is larger than that of the connecting portion.

15. A method for manufacturing a bipolar plate as described in claim 2, comprising: arranging the first separator and the second separator in a molding die so that the first through hole and the second through hole overlap each other entirely or partially when viewed in the stacking direction; injecting raw material for the connecting portion into the die and allowing it to harden, thereby forming the connecting portion and integrating the first separator and the second separator via the connecting portion.

16. A method for manufacturing a bipolar plate as described in claim 15, wherein the bipolar plate comprises a gasket that is integrally connected to the connecting portion, the raw material is the raw material for the connecting portion and the gasket, the molding die has a gasket-forming recess that forms the gasket, and in a mold-closed state, the gasket-forming recess communicates with the first through hole and the second through hole, and the raw material is injected into the mold and hardened to form the gasket together with the connecting portion.

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