Fuel battery cell and fuel battery cell stack

Abstract

To provide a fuel battery cell capable of securing a surface pressure of both of the fuel battery cells when forming a fuel battery cell stack by laminating the plurality of fuel battery cells even if a first separator and a second separator have a same construction each other, and provide a fuel battery cell stack.SOLUTION: A fuel battery cell 12 includes: a power generation part; and a first separator and a second separator that nip the power generation part. The first separator includes a plurality of first flow channels 32 that supplies a fuel gas to the power generation part. The second separator includes a plurality of second flow channels 35 that supplies an oxidant gas to the power generation part. The first and second separators have a same construction, and front and back surfaces of one of them are turned against those of the other one. Both of fuel gas supply holes 24, both of fuel gas exhaust holes 25, both of oxidant gas supply holes 27, both of oxidant gas exhaust holes 28, both of coolant medium body supply holes 30, and both of coolant medium body exhaust holes 31 are overlapped, and a plurality of first flow channels 32 and a plurality of second flow channels 35 are alternately crossed.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Conventionally, a fuel cell stack is known, for example, as shown in Patent Document 1. Such a fuel cell stack has a structure in which a plurality of fuel cells (power generation cells) are stacked and sandwiched between a pair of end plates on both sides in the stacking direction. The fuel cell has a support frame that supports a power generation section (membrane electrode assembly), and a pair of metallic separators that sandwich the power generation section and the support frame. Such separators are formed with projections and recesses that form a plurality of flow paths, for example, by pressing a thin metal plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-165808 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described fuel cell stack, when the separators of two fuel cells adjacent in the stacking direction come into contact with each other, the convex portions of the two separators come into contact with each other, forming a flow path between the concave portions of the two separators. However, the concave and convex portions of the two separators extend parallel to each other.

[0005] For this reason, if the two separators are misaligned in a direction perpendicular to both the extending direction of the projections and the stacking direction, the projections of one of the two separators will fit into the recesses of the other separator, resulting in a problem that the stacking thickness of the fuel cells will be thin in the portion where the projections and recesses fit together, making it impossible to ensure surface pressure between the fuel cells. [Means for solving the problem]

[0006] The means for solving the above problems and their effects will be described below. A fuel cell that solves the above problem is a plate-shaped fuel cell having a power generation section, and a first separator and a second separator that sandwich the power generation section, in which a fuel gas supply hole through which fuel gas is supplied and a fuel gas discharge hole through which the fuel gas is discharged are provided at a first position that faces across the center, an oxidant gas supply hole through which oxidant gas is supplied and an oxidant gas discharge hole through which the oxidant gas is discharged are provided at a second position that faces across the center, and a cooling medium supply hole through which a cooling medium is supplied and a cooling medium discharge hole through which the cooling medium is discharged are provided at a third position that faces across the center, the first position, the second position, and the third position are positions that are shifted from one another in a rotation direction about the center, and the first separator is The gist of the present invention is that the first separator has integral unevenness on one side that forms a plurality of first flow paths for supplying the fuel gas to a surface on one side of the power generation unit, and the second separator has integral unevenness on the other side that forms a plurality of second flow paths for supplying the oxidant gas to a surface on the other side of the power generation unit between the oxidant gas supply hole and the oxidant gas discharge hole, and the first separator and the second separator have the same configuration and are reversed relative to the other, and are arranged such that the fuel gas supply holes, the fuel gas discharge holes, the oxidant gas supply holes, the oxidant gas discharge holes, the coolant supply holes, and the coolant discharge holes overlap with each other when viewed in the thickness direction, and the plurality of first flow paths and the plurality of second flow paths extend so as to intersect with each other when viewed in the thickness direction.

[0007] According to the above configuration, when a fuel cell stack is formed by stacking a plurality of fuel cells, the first flow paths of the first separator and the second flow paths of the second separator directly overlap each other, but also intersect each other. Therefore, even if the overlapping positions of the integral unevenness forming the first flow paths of the first separator and the integral unevenness forming the second flow paths of the second separator are slightly shifted, it is possible to prevent these unevennesses from fitting together. Therefore, even if the first separator and the second separator have the same configuration, it is possible to ensure the surface pressure between the fuel cells when a fuel cell stack is formed by stacking a plurality of fuel cells. Incidentally, when the integral unevenness forming the first flow paths of the first separator and the integral unevenness forming the second flow paths of the second separator fit together, the stack thickness of the fuel cells at the part where they fit together becomes thin. Therefore, when a fuel cell stack is formed by stacking a plurality of fuel cells, the surface pressure between the fuel cells is not ensured.

[0008] A fuel cell stack that solves the above-mentioned problems is a fuel cell stack formed by stacking a plurality of plate-shaped fuel cells, each of which has a power generation section, and a first separator and a second separator that sandwich the power generation section, wherein the fuel cells are provided with a fuel gas supply hole through which fuel gas is supplied and a fuel gas discharge hole through which the fuel gas is discharged at a first position facing each other across the center, an oxidant gas supply hole through which oxidant gas is supplied and an oxidant gas discharge hole through which the oxidant gas is discharged at a second position facing each other across the center, and a cooling medium supply hole through which a cooling medium is supplied and a cooling medium discharge hole through which the cooling medium is discharged at a third position facing each other across the center, the first position, the second position, and the third position are positions that are shifted from one another in a rotational direction about the center, and the first separator is provided with a fuel gas supply hole through which a fuel gas is supplied and a fuel gas discharge hole through which the fuel gas is discharged at a second position facing each other across the center. The gist of the present invention is that the first separator has integral unevenness on one side that forms a plurality of first flow paths for supplying the fuel gas to a surface on one side of the power generation unit between the oxidant gas supply hole and the fuel gas discharge hole, and the second separator has integral unevenness on the other side that forms a plurality of second flow paths for supplying the oxidant gas to a surface on the other side of the power generation unit between the oxidant gas supply hole and the oxidant gas discharge hole, and the first separator and the second separator have the same configuration and are reversed relative to the other, and are arranged such that the fuel gas supply holes, the fuel gas discharge holes, the oxidant gas supply holes, the oxidant gas discharge holes, the cooling medium supply holes, and the cooling medium discharge holes overlap with each other when viewed in the thickness direction, and the plurality of first flow paths and the plurality of second flow paths extend so as to intersect with each other when viewed in the thickness direction.

[0009] According to the above configuration, the first flow paths of the first separator and the second flow paths of the second separator directly overlap each other, but cross each other. Therefore, even if the overlapping position of the integral unevenness forming the first flow paths of the first separator and the integral unevenness forming the second flow paths of the second separator is slightly shifted, it is possible to prevent these unevennesses from fitting together. Therefore, even if the first separator and the second separator have the same configuration, the surface pressure between the fuel cells can be ensured. Incidentally, when the integral unevenness forming the first flow paths of the first separator and the integral unevenness forming the second flow paths of the second separator fit together, the stacking thickness of the fuel cells at the fitted portion becomes thin. Therefore, the surface pressure between the fuel cells cannot be ensured. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of a fuel cell according to an embodiment; [Diagram 2] FIG. 2 is an exploded perspective view showing a fuel cell. [Diagram 3] FIG. 2 is a plan view of a fuel cell. [Figure 4] FIG. 4 is a plan view of the second separator. [Diagram 5] 4 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell. FIG. [Figure 6] 4 is a cross-sectional view of projections and recesses that form a first flow path of a first separator and a second flow path of a second separator. FIG. [Figure 7] FIG. 11 is a plan view of a fuel cell in a modified example. [Figure 8] FIG. 11 is a plan view of a second separator in a modified example. [Figure 9] FIG. 13 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell according to a modified example. [Figure 10] FIG. 11 is a plan view of a fuel cell according to another modified example. [Figure 11] FIG. 11 is a plan view of a second separator in another modified example. [Figure 12] FIG. 13 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell according to another modified example. [Figure 13] FIG. 11 is a plan view of a fuel cell in still another modified example. [Figure 14] FIG. 13 is a plan view of a second separator in still another modified example. [Figure 15] FIG. 13 is a plan view showing the positional relationship between a first flow path in a first separator and a second flow path in a second separator in a fuel cell according to still another modified example. [Figure 16] 13 is a cross-sectional view of projections and recesses forming a first flow path of a first separator and a second flow path of a second separator in a modified example. FIG. [Figure 17] 13 is a cross-sectional view of projections and recesses forming a first flow path of a first separator and a second flow path of a second separator in another modified example. FIG. [Figure 18] 13 is a cross-sectional view of projections and recesses forming a first flow path of a first separator and a second flow path of a second separator in still another modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment will now be described with reference to the drawings. <Fuel cell 11> As shown in FIG. 1, the fuel cell 11 includes a fuel cell stack 13 in which multiple disk-shaped fuel cell cells 12 that generate electricity are stacked in their thickness direction, and a pair of end plates 14 that sandwich the fuel cell stack 13 on either side in the stacking direction Z of the fuel cell cells 12.

[0012] The pair of end plates 14 have their outer edges fastened to each other by a plurality of bolts 15 and a plurality of nuts 16, thereby compressing the fuel cell stack 13 in the stacking direction Z. Between each of the pair of end plates 14 and the fuel cell stack 13, there are interposed terminal plates (not shown) for collecting current and insulating plates (not shown) for providing insulation.

[0013] <Fuel cell 12> 2, the fuel cell 12 has a disk-shaped support frame 18 supporting a rectangular sheet-shaped power generation unit 17, and a pair of disk-shaped metallic separators 19 that sandwich the support frame 18 supporting the power generation unit 17. Of the pair of separators 19, one located on the anode side is a first separator 20, and the other located on the cathode side is a second separator 21.

[0014] The power generation unit 17 is configured by sandwiching a membrane electrode assembly (MEA) between a pair of gas diffusion layers. The power generation unit 17 is supported in a state housed in a rectangular opening 22 formed in the center of a support frame 18.

[0015] A fuel gas supply hole 24 to which fuel gas is supplied and a fuel gas discharge hole 25 from which the fuel gas is discharged are provided at first positions 23, which are two positions facing each other across the center C of the fuel cell 12. The fuel gas is, for example, a gas containing hydrogen. An oxidant gas supply hole 27 to which oxidant gas is supplied and an oxidant gas discharge hole 28 from which the oxidant gas is discharged are provided at second positions 26, which are two positions facing each other across the center C of the fuel cell 12. The oxidant gas is, for example, a gas containing oxygen.

[0016] A cooling medium supply hole 30 through which the cooling medium is supplied and a cooling medium discharge hole 31 through which the cooling medium is discharged are provided at the third positions 29, which are two positions facing each other across the center C of the fuel cell 12. The cooling medium is, for example, cooling water. The first position 23, the second position 26, and the third position 29 of the fuel cell 12 are shifted from each other in the rotation direction about the center C as the rotation center, and are located approximately in the center between the center C and the outer edge.

[0017] In this embodiment, the second position 26 is a position rotated 60° in the forward direction from the first position 23 around the center C as the rotation center, and the third position 29 is a position rotated 60° in the reverse direction from the first position 23 around the center C as the rotation center. The angle between the line connecting the first position 23 and the center C and the line connecting the second position 26 and the center C is 60°. The angle between the line connecting the second position 26 and the center C and the line connecting the third position 29 and the center C is 60°. The angle between the line connecting the third position 29 and the center C and the line connecting the first position 23 and the center C is 60°.

[0018] Therefore, in the fuel cell 12, the fuel gas inlet 24, the fuel gas outlet 25, the oxidant gas inlet 27, the oxidant gas outlet 28, the coolant inlet 30, and the coolant outlet 31 are arranged at equal intervals of 60° around the center C. The fuel gas inlet 24, the fuel gas outlet 25, the oxidant gas inlet 27, the oxidant gas outlet 28, the coolant inlet 30, and the coolant outlet 31 in the fuel cell 12 are circular and each form a manifold extending in the stacking direction Z in the fuel cell stack 13 (see FIG. 1 ).

[0019] 3, in the fuel cell 12, the fuel gas supply hole 24, the fuel gas discharge hole 25, the oxidant gas supply hole 27, the oxidant gas discharge hole 28, the coolant supply hole 30, and the coolant discharge hole 31 are arranged to be symmetrical with respect to a line L passing through a center C. The line L is parallel to the fuel cell 12 and extends so as not to pass through the first position 23, the second position 26, and the third position 29.

[0020] In the fuel cell 12, the fuel gas discharge hole 25 and the oxidant gas discharge hole 28 are arranged at positions that are line symmetrical with respect to the line L. In the fuel cell 12, the coolant supply hole 30 and the coolant discharge hole 31 are arranged at positions that are line symmetrical with respect to the line L. In the fuel cell 12, the oxidant gas supply hole 27 and the fuel gas supply hole 24 are arranged at positions that are line symmetrical with respect to the line L.

[0021] In the fuel cell 12, the fuel gas discharge hole 25, the cooling medium supply hole 30, and the oxidant gas supply hole 27 are arranged on one side of the straight line L, while the oxidant gas discharge hole 28, the cooling medium discharge hole 31, and the fuel gas supply hole 24 are arranged on the other side of the straight line L.

[0022] <Separator 19> 2, 3, and 6, a plurality of first flow paths 32 that communicate between the fuel gas inlet 24 and the fuel gas outlet 25 are formed on the surface of the first separator 20 facing the power generation section 17. Each of the first flow paths 32 allows fuel gas to flow and supplies the fuel gas to one side of the power generation section 17 from the fuel gas inlet 24 to the fuel gas outlet 25. Each of the first flow paths 32 is formed by an integral concavo-convex surface formed by pressing the first separator 20. In this embodiment, the concavo-convex surface that constitutes each of the first flow paths 32 of the first separator 20 has a trapezoidal shape in cross section.

[0023] A recessed portion 33 on the power generation section 17 side of the unevenness of the first separator 20 constitutes a first flow path 32. The multiple recessed portions 33 constituting the multiple first flow paths 32 extend in parallel at regular intervals. Convex portions 34 are formed between the recessed portions 33 in the first separator 20. Regarding the unevenness of the first separator 20, the recessed portions 33 on one surface constitute the convex portions 34 on the other surface, and the convex portions 34 on one surface constitute the recessed portions 33 on the other surface.

[0024] The projections and recesses in the first separator 20 are arranged such that the recessed portions 33 and the protruding portions 34 are alternately arranged at equal intervals in the arrangement direction of the first flow paths 32. The first flow paths 32 in the first separator 20 extend in a meandering manner such that the flow direction of the fuel gas reverses multiple times (twice in this example). In other words, the first flow paths 32 are so-called serpentine flow paths.

[0025] 2, 4, and 6, a plurality of second flow paths 35 that communicate between the oxidant gas supply hole 27 and the oxidant gas discharge hole 28 are formed on the surface of the second separator 21 facing the power generation section 17. The oxidant gas flows through each of the second flow paths 35, and the oxidant gas is supplied to the other side surface of the power generation section 17 (the surface opposite to the first separator 20 side) from the oxidant gas supply hole 27 to the oxidant gas discharge hole 28. Each of the second flow paths 35 is formed by an integral concavo-convex structure formed by pressing the second separator 21. The concavo-convex structure that constitutes each of the second flow paths 35 of the second separator 21 in this embodiment has a trapezoidal shape in cross section.

[0026] A recessed portion 33 on the power generation section 17 side of the unevenness of the second separator 21 constitutes a second flow path 35. The multiple recessed portions 33 constituting the multiple second flow paths 35 extend in parallel at regular intervals. Convex portions 34 are formed between the recessed portions 33 in the second separator 21. Regarding the unevenness of the second separator 21, the recessed portions 33 on one surface constitute the convex portions 34 on the other surface, and the convex portions 34 on one surface constitute the recessed portions 33 on the other surface.

[0027] The projections and recesses in the second separator 21 are arranged such that the recessed portions 33 and the protruding portions 34 are alternately arranged at equal intervals in the arrangement direction of the second flow paths 35. The second flow paths 35 in the second separator 21 extend in a meandering manner such that the flow direction of the oxidant gas reverses multiple times (twice in this example). In other words, the second flow paths 35 are so-called serpentine flow paths.

[0028] 3 to 5, the first separator 20 and the second separator 21 have the same configuration. In the fuel cell 12, the first separator 20 and the second separator 21 are arranged in a manner in which one is upside down relative to the other. In this case, when viewed from the thickness direction, the first separator 20 and the second separator 21 have their respective fuel gas inlet holes 24, fuel gas outlet holes 25, oxidant gas inlet holes 27, oxidant gas outlet holes 28, cooling medium inlet holes 30, and cooling medium outlet holes 31 overlap with each other.

[0029] Furthermore, at this time, the first separator 20 and the second separator 21 extend such that the multiple first flow paths 32 of the first separator 20 and the multiple second flow paths 35 of the second separator 21 intersect with each other when viewed in the thickness direction. In this case, in the thickness direction of the first separator 20 and the second separator 21, the multiple first flow paths 32 and the multiple second flow paths 35 do not overlap with each other in a parallel state.

[0030] <Power generation by fuel cell stack 13> 1 and 2, in each of the fuel cells 12 constituting the fuel cell stack 13, a fuel gas is supplied to one surface (anode side) in the stacking direction Z of the power generation section 17, and an oxidant gas is supplied to the other surface (cathode side) in the stacking direction Z of the power generation section 17. As a result, the fuel cell 12 generates power based on an electrochemical reaction between the fuel gas and the oxidant gas in the power generation section 17. The fuel cell 12 generates heat by generating power.

[0031] A cooling medium flow path (not shown) is formed between a first separator 20 of one of two fuel cells 12 adjacent to each other in the stacking direction Z in the fuel cell stack 13 and a second separator 21 of the other of the two fuel cells 12. The cooling medium flow path (not shown) allows the cooling medium supplied from the cooling medium supply hole 30 to flow to the cooling medium discharge hole 31. As a result, each fuel cell 12 that generates heat by power generation is cooled by the cooling medium flowing through the cooling medium flow path (not shown).

[0032] <Operation of the embodiment> 1, 2 and 5, when an oxidant gas, a fuel gas, and a cooling medium are supplied to a fuel cell 11, power is generated in each fuel cell 12 constituting a fuel cell stack 13. In this case, the fuel cell stack 13 in the fuel cell 11 is pressed by a pair of end plates 14 so as to compress each fuel cell 12 in the stacking direction Z. At this time, of two fuel cells 12 adjacent to each other in the stacking direction Z, the multiple first flow paths 32 of one first separator 20 and the multiple second flow paths 35 of the other second separator 21 directly overlap with each other, but extend so as to intersect with each other.

[0033] Therefore, even if the overlapping position of the integral unevenness on the front and back of the first separator 20 forming the multiple first flow paths 32 and the integral unevenness on the front and back of the second separator 21 forming the multiple second flow paths 35 is slightly misaligned, these unevennesses do not fit together, so the stacking thickness of each fuel cell 12 is ensured. Therefore, even if the first separator 20 and the second separator 21 have the same configuration, the surface pressure between the fuel cell cells 12 is ensured when a plurality of fuel cell cells 12 are stacked to form the fuel cell stack 13. Therefore, the power generation performance of the fuel cell 11 is maintained.

[0034] In this regard, when the recesses and protrusions on the first separator 20 that form the first flow paths 32 and the recesses and protrusions on the second separator 21 that form the second flow paths 35 are fitted together, the stacking thickness of the fuel cells 12 at the fitted portion becomes thin. For this reason, when the fuel cells 12 are stacked together to form the fuel cell stack 13, the surface pressure between the fuel cells 12 is not ensured. This results in a decrease in the power generation performance of the fuel cell 11.

[0035] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) In the fuel cell 12, the first separator 20 and the second separator 21 have the same configuration and are inverted relative to the other, and are arranged such that when viewed from the thickness direction, the fuel gas supply holes 24, the fuel gas discharge holes 25, the oxidant gas supply holes 27, the oxidant gas discharge holes 28, the cooling medium supply holes 30, and the cooling medium discharge holes 31 overlap, and the multiple first flow paths 32 and the multiple second flow paths 35 extend so as to intersect with each other when viewed from the thickness direction.

[0036] According to the above configuration, when a fuel cell stack 13 is formed by stacking a plurality of fuel cells 12, the first flow paths 32 of the first separator 20 and the second flow paths 35 of the second separator 21 directly overlap each other, but also intersect each other. Therefore, even if the overlapping positions of the integral concaves and convexes forming the first flow paths 32 of the first separator 20 and the integral concaves and convexes forming the second flow paths 35 of the second separator 21 are slightly shifted, it is possible to prevent these concaves and convexes from fitting together. Therefore, even if the first separator 20 and the second separator 21 have the same configuration, it is possible to ensure the surface pressure between the fuel cell cells 12 when a fuel cell stack 13 is formed by stacking a plurality of fuel cells 12. As a result, the power generation performance of the fuel cell 11 can be maintained.

[0037] In this regard, when the recesses and protrusions on the first separator 20 that form the first flow paths 32 and the recesses and protrusions on the second separator 21 that form the second flow paths 35 are fitted together, the stacking thickness of the fuel cells 12 at the fitted portion becomes thin. Therefore, when the fuel cells 12 are stacked together to form the fuel cell stack 13, the surface pressure between the fuel cells 12 cannot be ensured. As a result, the power generation performance of the fuel cell 11 is reduced.

[0038] (2) In the fuel cell 12, the first flow passage 32 extends in a serpentine manner so that the flow direction of the fuel gas reverses multiple times, and the second flow passage 35 extends in a serpentine manner so that the flow direction of the oxidant gas reverses multiple times.

[0039] According to the above configuration, it is possible to increase the contact area between the power generation section 17 and the first flow passage 32, and the contact area between the power generation section 17 and the second flow passage 35. This makes it possible to improve the power generation efficiency of the fuel cell 12.

[0040] (3) In the fuel cell 12, the fuel gas supply hole 24, the fuel gas discharge hole 25, the oxidant gas supply hole 27, the oxidant gas discharge hole 28, the cooling medium supply hole 30, and the cooling medium discharge hole 31 are arranged so as to be symmetrical with respect to a straight line L passing through the center C.

[0041] According to the above configuration, by simply rotating one of the first separator 20 and the second separator 21 relative to the other about the line L as the center of rotation and thereby turning them over, it is possible to align the positions of the fuel gas supply holes 24, the fuel gas discharge holes 25, the oxidant gas supply holes 27, the oxidant gas discharge holes 28, the cooling medium supply holes 30, and the cooling medium discharge holes 31 when the first separator 20 and the second separator 21 are stacked.

[0042] (4) In the fuel cell 12, the fuel gas supply hole 24, the fuel gas discharge hole 25, the oxidant gas supply hole 27, the oxidant gas discharge hole 28, the cooling medium supply hole 30, and the cooling medium discharge hole 31 are arranged at 60° intervals around the center C.

[0043] According to the above configuration, the fuel gas supply hole 24, the fuel gas discharge hole 25, the oxidant gas supply hole 27, the oxidant gas discharge hole 28, the coolant supply hole 30, and the coolant discharge hole 31 can be arranged in a balanced manner at equal intervals in the rotational direction around the center C as the center of rotation.

[0044] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other as long as they are not technically inconsistent.

[0045] 7 to 9, the fuel cell 12 may be configured such that the second position 26 is a position rotated 40° in the forward direction from the third position 29 around the center C as the center of rotation, and the first position 23 is a position rotated 40° in the reverse direction from the third position 29 around the center C as the center of rotation. In this case, the first separator 20 and the second separator 21 in the fuel cell 12 have the same configuration and are arranged in a manner in which a plurality of first flow paths 32 and a plurality of second flow paths 35 extend so as to intersect with each other when viewed in the thickness direction. Furthermore, in this case, in the fuel cell 12, the fuel gas supply hole 24, the fuel gas discharge hole 25, the oxidant gas supply hole 27, the oxidant gas discharge hole 28, the cooling medium supply hole 30, and the cooling medium discharge hole 31 are arranged so as to be line-symmetrical with respect to a straight line L passing through the center C.

[0046] 10 to 12, the fuel cell 12 may be configured such that the second position 26 is a position rotated 20° in the forward direction from the third position 29 around the center C as the center of rotation, and the first position 23 is a position rotated 20° in the reverse direction from the third position 29 around the center C as the center of rotation. In this case, the first separator 20 and the second separator 21 in the fuel cell 12 have the same configuration and are arranged in such a manner that a plurality of first flow paths 32 and a plurality of second flow paths 35 extend so as to intersect with each other when viewed in the thickness direction. Furthermore, in this case, in the fuel cell 12, the fuel gas supply hole 24, the fuel gas discharge hole 25, the oxidant gas supply hole 27, the oxidant gas discharge hole 28, the cooling medium supply hole 30, and the cooling medium discharge hole 31 are arranged so as to be line-symmetrical with respect to a straight line L passing through the center C.

[0047] As shown in Figs. 13 to 15, the fuel cell 12 may be configured to have a regular octagonal shape. In this case, in the fuel cell 12, the fuel gas inlet 24, the fuel gas outlet 25, the oxidant gas inlet 27, the oxidant gas outlet 28, the cooling medium inlet 30, and the cooling medium outlet 31 are arranged in point symmetry with respect to the center C. The first separator 20 and the second separator 21 in the fuel cell 12 have the same configuration and are arranged such that the first flow paths 32 and the second flow paths 35 extend to intersect with each other when viewed in the thickness direction. The first separator 20 and the second separator 21 in the fuel cell 12 are arranged such that one is reversed with respect to the other and the positions of the holes 24, 25, 27, 28, 30, and 31 are aligned in the thickness direction. The first flow paths 32 in the first separator 20 extend in a serpentine shape so that the flow direction of the fuel gas reverses four times, and the second flow paths 35 in the second separator 21 extend in a serpentine shape so that the flow direction of the oxidizer gas reverses four times. Here, the second separator 21 is obtained by turning the first separator 20 upside down in the left-right direction and then rotating it 45° counterclockwise around the center C as the center of rotation.

[0048] As shown in FIG. 16, the unevenness that forms each of the first flow paths 32 in the first separator 20 and the unevenness that forms each of the second flow paths 35 in the second separator 21 may be configured to have a wavy shape in cross section.

[0049] As shown in FIG. 17, the unevenness that forms each of the first flow paths 32 in the first separator 20 and the unevenness that forms each of the second flow paths 35 in the second separator 21 may be configured to form a V-shape in cross section.

[0050] As shown in FIG. 18, the unevenness that forms each of the first flow paths 32 in the first separator 20 and the unevenness that forms each of the second flow paths 35 in the second separator 21 may be configured to form a W-shape in cross section.

[0051] Each of the first flow passages 32 and each of the second flow passages 35 may extend, for example, in a straight line, in a crank shape, or in a wavy shape. The fuel cell 12 may be polygonal or elliptical in shape.

[0052] <Additional Notes> The above embodiment includes the configurations described in the following supplementary notes. [Note 1] A plate-shaped fuel cell having a power generation section, and a first separator and a second separator sandwiching the power generation section, wherein a fuel gas supply hole through which a fuel gas is supplied and a fuel gas discharge hole through which the fuel gas is discharged are provided at a first position opposed to each other across the center, an oxidant gas supply hole through which an oxidant gas is supplied and an oxidant gas discharge hole through which the oxidant gas is discharged are provided at a second position opposed to each other across the center, and a cooling medium supply hole through which a cooling medium is supplied and a cooling medium discharge hole through which the cooling medium is discharged are provided at a third position opposed to each other across the center, the first position, the second position, and the third position are positions shifted from each other in a rotation direction about the center, and the first separator is disposed on one side of the power generation section between the fuel gas supply hole and the fuel gas discharge hole. the first separator has integral unevenness on one side that forms a plurality of first flow paths for supplying the fuel gas to the surface of the power generation section between the oxidant gas supply hole and the oxidant gas discharge hole, and the first separator and the second separator have integral unevenness on one side that forms a plurality of second flow paths for supplying the oxidant gas to the surface of the other side of the power generation section between the oxidant gas supply hole and the oxidant gas discharge hole, the first separator and the second separator have the same configuration and are reversed relative to the other, and are arranged such that the fuel gas supply holes, the fuel gas discharge holes, the oxidant gas supply holes, the oxidant gas discharge holes, the coolant supply holes, and the coolant discharge holes overlap with each other when viewed in the thickness direction, and the plurality of first flow paths and the plurality of second flow paths extend so as to intersect with each other when viewed in the thickness direction.

[0053] [Appendix 2] The fuel cell described in [Appendix 1], characterized in that the first flow path extends in a serpentine manner so that the flow direction of the fuel gas reverses multiple times, and the second flow path extends in a serpentine manner so that the flow direction of the oxidant gas reverses multiple times.

[0054] [Appendix 3] A fuel cell according to [Appendix 1] or [Appendix 2], characterized in that the fuel gas supply hole, the fuel gas exhaust hole, the oxidant gas supply hole, the oxidant gas exhaust hole, the cooling medium supply hole, and the cooling medium exhaust hole are arranged so as to be linearly symmetrical with respect to a straight line passing through the center.

[0055] [Appendix 4] A fuel cell described in any one of [Appendix 1] to [Appendix 3], characterized in that the fuel gas supply hole, the fuel gas exhaust hole, the oxidant gas supply hole, the oxidant gas exhaust hole, the cooling medium supply hole, and the cooling medium exhaust hole are arranged at 60° intervals around the center. [Explanation of symbols]

[0056] 11...fuel cell 12...Fuel cell 13...Fuel cell stack 14…End plate 15…Volts 16…Nut 17…Power generation section 18…Support frame 19…Separator 20…First separator 21…Second separator 22…Opening 23…1st position 24...Fuel gas supply hole 25…Fuel gas exhaust hole 26...2nd position 27...Oxidant gas supply hole 28...Oxidant gas exhaust hole 29…3rd position 30…Cooling medium supply hole 31…Cooling medium discharge hole 32…First flow path 33…Concave part 34...Convex part 35…Second flow path C…center L…straight line Z…Stacking direction

Claims

1. A plate-shaped fuel cell having a power generation section, and a first separator and a second separator sandwiching the power generation section, a fuel gas supply hole through which a fuel gas is supplied and a fuel gas discharge hole through which the fuel gas is discharged are provided at first positions opposed to each other across the center, an oxidizer gas supply hole through which an oxidizer gas is supplied and an oxidizer gas discharge hole through which the oxidizer gas is discharged are provided at a second position opposed to each other across the center, and a cooling medium supply hole through which a cooling medium is supplied and a cooling medium discharge hole through which the cooling medium is discharged are provided at a third position opposed to each other across the center, the first position, the second position, and the third position are positions shifted from one another in a rotation direction about the center, the first separator has projections and recesses on one side thereof that form a plurality of first flow paths for supplying the fuel gas to a surface of one side of the power generation section between the fuel gas supply hole and the fuel gas discharge hole, the second separator has projections and recesses on one side thereof that form a plurality of second flow paths for supplying the oxidant gas to a surface on the other side of the power generation section between the oxidant gas supply hole and the oxidant gas discharge hole, a fuel cell characterized in that the first separator and the second separator have the same configuration, one is inverted relative to the other, and are arranged in such a manner that, when viewed from the thickness direction, the fuel gas supply holes, the fuel gas discharge holes, the oxidant gas supply holes, the oxidant gas discharge holes, the cooling medium supply holes, and the cooling medium discharge holes overlap, and a plurality of the first flow paths and a plurality of the second flow paths extend so as to intersect with each other when viewed from the thickness direction.

2. The first flow passage extends in a serpentine manner such that a flow direction of the fuel gas reverses multiple times, 2. The fuel cell according to claim 1, wherein the second flow passage extends in a meandering manner such that the flow direction of the oxidant gas is reversed a number of times.

3. 3. The fuel cell according to claim 1, wherein the fuel gas supply hole, the fuel gas exhaust hole, the oxidant gas supply hole, the oxidant gas exhaust hole, the cooling medium supply hole, and the cooling medium exhaust hole are arranged so as to be symmetrical with respect to a straight line passing through the center.

4. 3. The fuel cell according to claim 1, wherein the fuel gas supply hole, the fuel gas exhaust hole, the oxidant gas supply hole, the oxidant gas exhaust hole, the cooling medium supply hole, and the cooling medium exhaust hole are arranged at 60° intervals around the center.

5. A fuel cell stack formed by stacking a plurality of plate-shaped fuel cells, each of which has a power generation section and a first separator and a second separator sandwiching the power generation section, The fuel cell is provided with a fuel gas supply hole through which a fuel gas is supplied and a fuel gas discharge hole through which the fuel gas is discharged, at a first position opposed to each other across the center, an oxidizer gas supply hole through which an oxidizer gas is supplied and an oxidizer gas discharge hole through which the oxidizer gas is discharged, at a second position opposed to each other across the center, and a cooling medium supply hole through which a cooling medium is supplied and a cooling medium discharge hole through which the cooling medium is discharged, at a third position opposed to each other across the center, the first position, the second position, and the third position are positions shifted from one another in a rotation direction about the center, the first separator has projections and recesses on one side thereof that form a plurality of first flow paths for supplying the fuel gas to a surface of one side of the power generation section between the fuel gas supply hole and the fuel gas discharge hole, the second separator has projections and recesses on one side thereof that form a plurality of second flow paths for supplying the oxidant gas to a surface on the other side of the power generation section between the oxidant gas supply hole and the oxidant gas discharge hole, a fuel cell stack comprising: the first separator and the second separator, each having an identical configuration, one of which is inverted relative to the other; and which are arranged such that, when viewed in the thickness direction, the fuel gas supply holes, the fuel gas discharge holes, the oxidant gas supply holes, the oxidant gas discharge holes, the cooling medium supply holes, and the cooling medium discharge holes overlap; and, when viewed in the thickness direction, a plurality of the first flow paths and a plurality of the second flow paths extend so as to intersect with each other.

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