Fuel battery cell

Abstract

To provide a fuel battery cell with which it is possible to reduce the variation in pressure losses of a reaction gas flowing in a gas diffusion layer.SOLUTION: The fuel battery cell comprises a power generation unit, and a pair of separators 17 holding the power generation unit therebetween. On the power generation unit side surface of the separators 17 is formed a gas flow path 24 in which a reaction gas flows. The gas flow path 24 includes a plurality of first extensions Lg1 to Lg3 extending in a first direction, and second extensions Tg1, Tg2 extending in a second direction different from the first direction. The second extensions Tg1, Tg2 connect the ends of the first extensions Lg1 to Lg3 to each other. Between the adjacent first extensions Lg1, Lg2 and between the adjacent first extensions Lg2, Lg3 are disposed first ribs 28 that demarcate these extensions and extend in the first direction, respectively. Upward of the first rib 28 is disposed a second rib 29 extending in the first direction. The second ribs 29 of the pair of separators 17 extend so as to cross each other when seen from a direction in which the pair of separators 17 hold the power generation unit therebetween.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Generally, a fuel cell includes a cell stack formed by stacking a plurality of fuel cell units, and a pair of end plates that sandwich the cell stack in the stacking direction of the fuel cell units. A conventional fuel cell unit for a fuel cell is shown in, for example, Patent Document 1. This fuel cell unit includes a membrane electrode assembly and a pair of separators that sandwich the membrane electrode assembly, and has an overall rectangular plate shape. A pair of gas diffusion layers is disposed between the membrane electrode assembly and the pair of separators.

[0003] Gas flow channels through which reactant gases flow are formed on the surface of each separator facing the membrane electrode stack. These gas flow channels are formed by depressions formed by press molding. The gas flow channels of one of the pair of separators are separated by a plurality of linearly extending ribs, forming a so-called serpentine flow channel that extends in a serpentine pattern. When the gas flow channels are serpentine, a so-called path cut may occur in the region where the ribs of the gas diffusion layer abut, where the reactant gas passes through the pores of the gas diffusion layer and passes through the ribs.

[0004] To prevent this, some of the ribs have protrusions that extend linearly along the ribs. The protrusions protrude from the ribs toward the gas diffusion layer and penetrate into the gas diffusion layer. This causes the gas diffusion layer to be partially compressed by the protrusions, reducing the number of pores through which the reactant gas can pass in the areas where the protrusions penetrate. This prevents the above-mentioned path cutting from occurring in the areas of the gas diffusion layer that are compressed by the protrusions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-69541 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-mentioned fuel cell, if both gas flow paths of the pair of separators are serpentine flow paths, forming protrusions on the ribs as described above to suppress the occurrence of the path cuts can cause the following problems.

[0007] When a pair of separators sandwich a pair of gas diffusion layers, the protrusions of one of the pair of separators overlap when viewed from the direction in which the pair of separators sandwich the membrane electrode stack. In this case, because each protrusion extends linearly, if the positions of the pair of separators are shifted in a direction perpendicular to the sandwiching direction, the protrusions of the pair of separators may not overlap at all when viewed from the sandwiching direction.

[0008] For this reason, when a plurality of fuel cells are manufactured, some of the fuel cells have the protrusions of the pair of separators completely overlapping when viewed from the sandwiching direction, while others have no overlap at all. In such cases, a large difference occurs in the compression ratio of the pair of gas diffusion layers between the protrusions of the pair of separators when the protrusions of the pair of separators completely overlap when viewed from the sandwiching direction and when they do not overlap at all among the plurality of fuel cells.

[0009] As a result, there is a problem in that the pressure loss of the reactant gas flowing through the gas diffusion layer varies greatly among the plurality of fuel cell units that make up the fuel cell. [Means for solving the problem]

[0010] The means for solving the above problems and their effects will be described below. A fuel cell that solves the above-described problems is a fuel cell comprising a power generation section including a membrane electrode assembly and a pair of gas diffusion layers sandwiching the membrane electrode assembly, and a pair of separators sandwiching the power generation section, wherein a gas flow path through which a reactant gas flows is provided on a surface of the separator facing the power generation section, the gas flow path having a plurality of first extension parts that extend in a first direction and are arranged in parallel in an orthogonal direction that is orthogonal to the first direction, and a second extension part that is connected to an end of the first extension part in the first direction and extends in a second direction different from the first direction, and the plurality of first extension parts have flow directions of the reactant gas in the first extension parts adjacent to each other in the orthogonal direction opposite each other, and the second extension part The separator connects a downstream end of one of the first extension portions adjacent to each other in the perpendicular direction in the flow direction to an upstream end of the other first extension portion in the flow direction, a first rib is provided between the first extension portions adjacent to each other in the perpendicular direction and extends in the first direction to separate the first extension portions adjacent to each other in the perpendicular direction, a second rib is provided on the first rib and extends in the first direction, and the second rib of one of the pair of separators and the second rib of the other separator extend so as to intersect with each other when viewed from the direction in which the pair of separators sandwich the power generation unit.

[0011] According to the above configuration, the second ribs of the pair of separators are recessed into the pair of gas diffusion layers, respectively, thereby preventing the reactant gas from flowing over the first ribs between adjacent first extension portions in the perpendicular direction without passing through the second extension portions. In this case, the second ribs of the pair of separators extend so as to intersect with each other when viewed from the direction in which the pair of separators sandwich the power generation unit. Therefore, regardless of whether the positions of the pair of separators are shifted in the direction perpendicular to the sandwiching direction, the second ribs intersect at a point when viewed from the sandwiching direction, but do not continuously overlap for more than a certain length. Therefore, the pair of gas diffusion layers do not form a region that is continuously compressed by the second ribs from both sides in the sandwiching direction for more than a certain length, thereby preventing an increase in pressure loss of the reactant gas flowing through the gas diffusion layers due to compression of the second ribs. In other words, whether the positions of a pair of separators are shifted relative to each other in a direction perpendicular to the sandwiching direction or not, the pressure loss of the reactant gas flowing through the gas diffusion layer does not change significantly, thereby reducing the variation in pressure loss of the reactant gas flowing through the gas diffusion layer between multiple fuel cell cells.

[0012] Incidentally, when the second ribs are linearly overlapping each other continuously for a certain length or more, depending on the direction in which the pair of separators are misaligned, the pressure loss of the reactant gas flowing through the gas diffusion layer changes significantly when the pair of separators are misaligned from each other and when they are not, resulting in a large variation in the pressure loss of the reactant gas flowing through the gas diffusion layer between multiple fuel cell cells. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a fuel cell stack according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing the fuel cell of FIG. [Figure 3] FIG. 2 is a plan view showing the gas flow paths of the separator of FIG. [Figure 4] FIG. 4 is an enlarged view of a main part of FIG. 3. [Figure 5] FIG. 5 is a schematic cross-sectional view taken along line 5-5 in FIG. [Figure 6] FIG. 2 is a schematic plan view showing a part of the fuel cell of FIG. [Figure 7] FIG. 2 is a cross-sectional view showing a main part of the fuel cell of FIG. [Figure 8] FIG. 2 is a cross-sectional view showing a main part of the fuel cell of FIG. [Figure 9] FIG. 10 is a cross-sectional schematic view of a second rib of a modified example. [Figure 10] FIG. 10 is a cross-sectional schematic view of a second rib of a modified example. [Figure 11] FIG. 10 is a schematic plan view showing the overlapping state of second ribs in a pair of separators of a fuel cell according to a modified example. [Figure 12] FIG. 10 is a schematic plan view showing the overlapping state of second ribs in a pair of separators of a fuel cell according to a modified example. [Figure 13] FIG. 10 is a schematic plan view showing the overlapping state of second ribs in a pair of separators of a fuel cell according to a modified example. [Figure 14] FIG. 10 is a schematic plan view showing the overlapping state of second ribs in a pair of separators of a fuel cell according to a modified example. [Figure 15] FIG. 10 is a schematic plan view showing the overlapping state of second ribs in a pair of separators of a fuel cell according to a modified example. [Figure 16] FIG. 10 is a schematic plan view showing the overlapping state of second ribs in a pair of separators of a fuel cell according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment will be described below with reference to the drawings. <Fuel cell stack 11> As shown in FIG. 1, a fuel cell stack 11 is formed by stacking a plurality of fuel cells 12 one on top of the other.

[0015] <Fuel cell 12> 2, the fuel cell 12 has, for example, a square plate shape. That is, the fuel cell 12 has a pair of first sides 13 extending parallel to each other and a pair of second sides 14 perpendicular to the first sides 13 and extending parallel to each other.

[0016] In the following description, the stacking direction Z of the fuel cell 12 will be simply referred to as the stacking direction Z. The direction in which the first side 13 extends will be referred to as the X-axis direction, and the direction in which the second side 14 extends will be referred to as the Y-axis direction. The stacking direction Z, the X-axis direction, and the Y-axis direction are perpendicular to each other.

[0017] The fuel cell 12 has a fuel gas supply manifold M1 that supplies fuel gas to the inside of the fuel cell 12 and a fuel gas discharge manifold M2 that discharges the fuel gas to the outside of the fuel cell 12. The fuel cell 12 has an oxidant gas supply manifold M3 that supplies oxidant gas to the inside of the fuel cell 12 and an oxidant gas discharge manifold M4 that discharges the oxidant gas to the outside of the fuel cell 12.

[0018] The manifolds M1 to M4 are, for example, oval shapes that are long in the Y-axis direction. The fuel gas supply manifold M1 and the oxidant gas discharge manifold M4 are located at one end of the fuel cell 12 in the X-axis direction, and are lined up in this order from one side to the other in the Y-axis direction.

[0019] The fuel gas discharge manifold M2 and the oxidant gas supply manifold M3 are located at the other end opposite to one side in the X-axis direction of the fuel cell 12, and are arranged in this order from the other side to one side in the Y-axis direction. The fuel gas is, for example, hydrogen. The oxidant gas is, for example, air.

[0020] 1 and 2, the fuel cell 12 has two refrigerant supply manifolds M5 that supply a cooling medium to the inside of the fuel cell stack 11, and two refrigerant discharge manifolds M6 that discharge the cooling medium to the outside of the fuel cell stack 11. Each of the refrigerant supply manifolds M5 and each of the refrigerant discharge manifolds M6 has, for example, an oval shape that is long in the X-axis direction.

[0021] The two coolant supply manifolds M5 are located at the other end of the fuel cell 12 in the Y-axis direction and are aligned at a distance from each other in the X-axis direction. The two coolant discharge manifolds M6 are located at one end of the fuel cell 12 in the Y-axis direction and are aligned at a distance from each other in the X-axis direction. The coolant is, for example, water.

[0022] The fuel cell 12 includes a power generation section 15, a frame 16, and a pair of separators 17. The power generation section 15 is sheet-shaped. The frame 16 surrounds the outer periphery of the power generation section 15. The pair of separators 17 sandwich the power generation section 15 and frame 16 from both sides in the stacking direction Z. The stacking direction Z is an example of the "direction in which the pair of separators 17 sandwich the power generation section 15." The power generation section 15 and separators 17 are, for example, square-shaped in a plan view. The frame 16 is, for example, square-frame-shaped in a plan view.

[0023] <Power Generation Unit 15> As shown in FIG. 1 , the power generation section 15 includes a membrane electrode assembly 18, and an anode-side gas diffusion layer 19 and a cathode-side gas diffusion layer 20 that sandwich the membrane electrode assembly 18. The anode-side gas diffusion layer 19 and the cathode-side gas diffusion layer 20 are an example of a "pair of gas diffusion layers." Although not shown, the membrane electrode assembly 18 includes an electrolyte membrane, and an anode electrode catalyst layer and a cathode electrode catalyst layer that sandwich the electrolyte membrane. The anode-side gas diffusion layer 19 is laminated on the anode electrode catalyst layer. The cathode-side gas diffusion layer 20 is laminated on the cathode electrode catalyst layer.

[0024] Fuel gas is supplied to the anode side surface of the power generation unit 15 through a fuel gas supply manifold M1. Oxidant gas is supplied to the cathode side surface of the power generation unit 15 through an oxidant gas supply manifold M3. As a result, power is generated in the power generation unit 15 by an electrochemical reaction between the fuel gas and the oxidant gas.

[0025] In the fuel cell stack 11, each fuel cell 12 generates heat as the power generation section 15 generates power. For this reason, a cooling flow path 21, which will be described later, is formed inside the fuel cell stack 11. A cooling medium is supplied to the cooling flow path 21 through a refrigerant supply manifold M5.

[0026] <Frame 16> 2, the frame 16 is made of an insulating resin material. The frame 16 has a housing hole 22 in the center that houses the power generation unit 15. The frame 16 has through holes hf1 to hf6 that form manifolds M1 to M6 on the outer periphery of the housing hole 22. The frame 16 has a plurality of grooves 23 between the housing hole 22 and each of the through holes hf1 to hf4.

[0027] The plurality of grooves 23 formed between the accommodating hole 22 and each of the through holes hf1, hf2 and the plurality of grooves 23 formed between the accommodating hole 22 and each of the through holes hf3, hf4 are arranged on opposite sides of both surfaces of the frame 16 in the stacking direction Z. That is, the plurality of grooves 23 formed between the accommodating hole 22 and each of the through holes hf1, hf2 are arranged on one side of both surfaces of the frame 16 in the stacking direction Z. On the other hand, the plurality of grooves 23 formed between the accommodating hole 22 and each of the through holes hf3, hf4 are arranged on the other side of both surfaces of the frame 16 in the stacking direction Z.

[0028] The multiple grooves 23 are arranged in parallel at intervals in the Y-axis direction. Each groove 23 has an oval shape that is long in the X-axis direction. One end of each groove 23 communicates in the stacking direction Z with one of the through holes hs1 to hs4 of the separator 17, which will be described later. The other end of each groove 23, opposite to the one end, communicates in the stacking direction Z with the gas flow path 24 of the separator 17, which will be described later. Each manifold M1 to M4 communicates with the gas flow path 24 via, for example, seven grooves 23.

[0029] <Separator 17> 1 and 2, the separator 17 is formed by press-forming a metal plate such as stainless steel or titanium alloy. One of the pair of separators 17 is disposed on the anode side of the power generation unit 15, and the other is disposed on the cathode side of the power generation unit 15.

[0030] In the following description, the separator 17 placed on the anode side of the power generation section 15 may be referred to as an anode separator 25, and the separator 17 placed on the cathode side of the power generation section 15 may be referred to as a cathode separator 26.

[0031] The anode separator 25 and the cathode separator 26 have the same configuration. The anode separator 25 and the cathode separator 26 are disposed in positions that are inverted relative to the power generation section 15, with an imaginary axis V as the axis of inversion. The imaginary axis V passes through the center of the separator 17 in the X-axis direction and extends in the Y-axis direction.

[0032] Separator 17 has through holes hs1 to hs6 that form manifolds M1 to M6. As described above, anode separator 25 and cathode separator 26 are arranged in an inverted position relative to each other with respect to power generation section 15. Therefore, through hole hs1 of anode separator 25 and through hole hs3 of cathode separator 26 communicate with each other, and through hole hs2 of anode separator 25 and through hole hs4 of cathode separator 26 communicate with each other.

[0033] The through hole hs3 of the anode separator 25 and the through hole hs1 of the cathode separator 26 are in communication with each other, and the through hole hs4 of the anode separator 25 and the through hole hs2 of the cathode separator 26 are in communication with each other. The through hole hs5 of the anode separator 25 and the through hole hs5 of the cathode separator 26 are in communication with each other, and the through hole hs6 of the anode separator 25 and the through hole hs6 of the cathode separator 26 are in communication with each other.

[0034] 3, groove-like gas flow paths 24 through which the reactant gas flows and ribs 27 extending along the gas flow paths 24 are arranged alternately on the surface of the separator 17 facing the power generation section 15. The separator 17 has, for example, eight gas flow paths 24 extending in parallel with one another. Each gas flow path 24 has a serpentine shape that extends in a serpentine pattern from the through hole hs1 to the through hole hs2.

[0035] 2 and 3, a fuel gas flows as a reactant gas through the gas flow passage 24 of the anode separator 25. An oxidant gas flows as a reactant gas through the gas flow passage 24 of the cathode separator 26. The reactant gas flows through the gas flow passage 24 and is supplied to the power generation unit 15. The reactant gas supply system in the fuel cell stack 11 is, for example, a so-called counterflow system in which the fuel gas and the oxidant gas flow in opposite directions.

[0036] In the following description, the upstream side of the gas flow passage 24 in the flow direction of the reaction gas will be simply referred to as the upstream side, and the downstream side in the flow direction will be simply referred to as the downstream side. Each gas flow path 24 is formed in a substantially S-shape by connecting the first extension portions Lg1 to Lg3 with the second extension portions Tg1 and Tg2. The reactant gas flows through the first extension portion Lg1, the second extension portion Tg1, the first extension portion Lg2, the second extension portion Tg2, and the first extension portion Lg3 in this order. The first extension portions Lg1 to Lg3 are arranged in parallel and adjacent to each other in the Y-axis direction. The first extension portions Lg1 to Lg3 extend in the X-axis direction in a wavy, meandering manner. The X-axis direction is an example of a "first direction." The Y-axis direction, which is perpendicular to the X-axis direction, is an example of an "orthogonal direction."

[0037] The second extension portions Tg1, Tg2 extend linearly and inclined relative to the imaginary axis V so as to be positioned to one side in the X-axis direction as they move downstream. The direction in which the second extension portions Tg1, Tg2 extend is an example of a "second direction" different from the above-mentioned "first direction."

[0038] The upstream end of the first extension portion Lg1 is connected to the through hole hs1 via a groove 23 in the frame 16. The second extension portion Tg1 connects the downstream end of the first extension portion Lg1 to the upstream end of the first extension portion Lg2. The second extension portion Tg2 connects the downstream end of the first extension portion Lg2 to the upstream end of the first extension portion Lg3. The downstream end of the first extension portion Lg3 is connected to the through hole hs2 via the groove 23.

[0039] When the reactant gas flows from the first extension portion Lg1 to the first extension portion Lg2 via the second extension portion Tg1, and when the reactant gas flows from the first extension portion Lg2 to the first extension portion Lg3 via the second extension portion Tg2, the flow direction of the reactant gas reverses. Therefore, the second extension portions Tg1 and Tg2 form turning portions of the gas flow path 24. The first extension portions Lg1 and Lg3 and the first extension portion Lg2, which are adjacent to each other in the Y-axis direction, have reactant gas flow directions opposite to each other in the X-axis direction.

[0040] 3 to 5, first ribs 28 extending in the X-axis direction are provided between the first extension portion Lg1 and the first extension portion Lg2 that are adjacent in the Y-axis direction, and between the first extension portion Lg2 and the first extension portion Lg3 that are adjacent in the Y-axis direction. The first rib 28 provided between the first extension portion Lg1 and the first extension portion Lg2 separates the first extension portion Lg1 from the first extension portion Lg2. The first rib 28 provided between the first extension portion Lg2 and the first extension portion Lg3 separates the first extension portion Lg2 from the first extension portion Lg3.

[0041] The first rib 28 separating the first extending portion Lg1 and the first extending portion Lg2 extends in the X-axis direction in a wavy, meandering pattern along the first extending portion Lg1 and the first extending portion Lg2. The first rib 28 separating the first extending portion Lg2 and the first extending portion Lg3 extends in the X-axis direction in a wavy, meandering pattern along the first extending portion Lg2 and the first extending portion Lg3.

[0042] A second rib 29 is provided on the first rib 28. The second rib 29 is disposed in the center of the width direction on the first rib 28 and extends in the X-axis direction in a wavy, meandering pattern along the first rib 28. The second rib 29 extends over almost the entire first rib 28 in the X-axis direction. The first rib 28 and the second rib 29 are, for example, both substantially trapezoidal in cross section.

[0043] In the following description, the second rib 29 of the anode separator 25 may be referred to as the second rib 29A, and the second rib 29 of the cathode separator 26 may be referred to as the second rib 29B, for distinction.

[0044] 6, of the pair of separators 17 in the fuel cell 12, the second rib 29A of one anode separator 25 and the second rib 29B of the other cathode separator 26 extend so as to intersect with each other when viewed from the stacking direction Z. That is, the second ribs 29A and 29B are out of phase with each other in the X-axis direction when viewed from the stacking direction Z. Therefore, if the second ribs 29A and 29B are assumed to be lines, the second ribs 29A and 29B intersect at a point when viewed from the stacking direction Z, but do not continuously overlap for more than a certain length.

[0045] <Cooling channel 21> 1, in a fuel cell stack 11, of two adjacent fuel cell cells 12 in the stacking direction Z, an anode separator 25 constituting one of the fuel cell cells 12 and a cathode separator 26 constituting the other fuel cell cell 12 are in contact with each other. A cooling flow path 21 through which a cooling medium flows is formed between the anode separator 25 and the cathode separator 26 that are in contact with each other in the two fuel cell cells 12 adjacent to each other in the stacking direction Z. Although not shown, a gasket that seals the space between the two fuel cell cells 12 is provided between the anode separator 25 and the cathode separator 26 that are in contact with each other.

[0046] 1 and 2, the separator 17 has a plurality of cooling grooves 30 that form the cooling flow path 21. The cooling grooves 30 are formed on the surface of the separator 17 opposite to the surface on which the gas flow path 24 is formed. The cooling grooves 30 are formed by the rear surface shape of the rib 27. The cooling grooves 30 have a serpentine shape that extends in a serpentine manner from the through hole hs1 to the through hole hs2.

[0047] The cooling flow path 21 is formed by the gap between the cooling groove 30 of the anode separator 25 and the cooling groove 30 of the cathode separator 26. The cooling medium supplied from the coolant supply manifold M5 flows through the cooling flow path 21 and is discharged from the coolant discharge manifold M6.

[0048] <Operation of the embodiment> 7, in the fuel cell 12, the second rib 29A of the anode separator 25 is recessed into the anode-side gas diffusion layer 19, and the second rib 29B of the cathode separator 26 is recessed into the cathode-side gas diffusion layer 20. The regions of the gas diffusion layers 19, 20 where the second ribs 29A, 29B are recessed are compressed, so that the pressure loss during reactant gas flow is greater than in other regions. This prevents reactant gas from flowing over the first rib 28 between the first extension portions Lg1, Lg2 adjacent to each other in the Y-axis direction and between the first extension portions Lg2, Lg3 adjacent to each other without passing through the second extension portion Tg1 and the second extension portion Tg2, respectively.

[0049] 6, the second ribs 29A, 29B both extend in a wavy, meandering manner in the X-axis direction and also extend so as to intersect with each other when viewed from the stacking direction Z. The positions of the second ribs 29A, 29B may be slightly misaligned in a direction perpendicular to the stacking direction Z, such as the X-axis direction or Y-axis direction, due to errors that may occur when assembling the fuel cell 12.

[0050] 8, the region where the second ribs 29A, 29B overlap each other when viewed from the stacking direction Z in the gas diffusion layers 19, 20 is compressed by the second ribs 29A, 29B from both sides in the stacking direction Z, forming a high compression region R where the compression ratio is extremely high. In the high compression region R, the pressure loss when the reactant gas flows becomes extremely high.

[0051] For this reason, when the high compression regions R are formed continuously over a range of a certain length or more in the gas diffusion layers 19, 20, the pressure loss when the reactant gas flows becomes large in the fuel cell 12. On the other hand, as shown in Fig. 7, when the high compression regions R are not formed continuously over a range of a certain length or more in the gas diffusion layers 19, 20, the pressure loss when the reactant gas flows is kept small in the fuel cell 12.

[0052] If the pressure loss when the reactant gas flows between the multiple fuel cells 12 that make up the fuel cell stack 11 varies greatly, the amount of reactant gas flowing also varies greatly, which poses a risk of reducing the power generation performance of the fuel cell stack 11.

[0053] In this regard, in the fuel cell 12 of this embodiment, the second ribs 29A, 29B overlap at a point when viewed from the stacking direction Z, regardless of whether their positions are shifted in the direction perpendicular to the stacking direction Z, but do not overlap continuously over a range of at least a certain length. In other words, in the fuel cell 12 of this embodiment, regardless of whether the second ribs 29A, 29B are shifted in the direction perpendicular to the stacking direction Z, high compression regions R are not formed continuously in the gas diffusion layers 19, 20 over a range of at least a certain length.

[0054] That is, in the fuel cell 12 of this embodiment, whether or not the second ribs 29A, 29B are misaligned in the direction perpendicular to the stacking direction Z, the pressure loss of the reactant gas flowing through the gas diffusion layers 19, 20 does not change significantly. Therefore, the variation in pressure loss when the reactant gas flows between the multiple fuel cell units 12 that make up the fuel cell stack 11 is reduced, and therefore the variation in the amount of flowing reactant gas is also reduced. This reduces the risk of a decrease in the power generation performance of the fuel cell stack 11.

[0055] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) In the fuel cell 12, the second rib 29A of the anode separator 25 and the second rib 29B of the cathode separator 26 extend so as to intersect with each other when viewed from the stacking direction Z.

[0056] According to the above configuration, the operation of the above-described embodiment reduces the variation in pressure loss when reactant gas flows between the plurality of fuel cells 12 that make up the fuel cell stack 11, and therefore reduces the variation in the amount of reactant gas flowing. This reduces the risk of a decrease in the power generation performance of the fuel cell stack 11.

[0057] (2) In the fuel cell 12, the first extending portions Lg1 to Lg3 extend in the X-axis direction while meandering in a wave-like manner. According to the above configuration, when a plurality of fuel cell cells 12 are stacked to form a fuel cell stack 11, the cooling medium can flow more smoothly through the cooling flow path 21 between adjacent fuel cell cells 12 in the stacking direction Z than when the first extension portions Lg1 to Lg3 extend linearly in the X-axis direction.

[0058] (3) In the fuel cell 12, the second rib 29A of the anode separator 25 and the second rib 29B of the cathode separator 26 both extend in the X-axis direction in a wavy, meandering manner. The second ribs 29A and 29B are out of phase with each other when viewed from the stacking direction Z.

[0059] According to the above configuration, the second ribs 29A, 29B extend in the X-axis direction in a wavy, meandering manner along the first extension portions Lg1 to Lg3 of the gas flow path 24, which makes it difficult for excess space to be generated. This allows for effective use of the space in the fuel cell 12, which contributes to the miniaturization of the fuel cell 12. In addition, the second ribs 29A, 29B are out of phase with each other when viewed from the stacking direction Z, which provides the same effect as (1) above.

[0060] (4) In the fuel cell 12, the anode separator 25 and the cathode separator 26 have the same configuration. According to the above configuration, the number of parts constituting the fuel cell 12 can be reduced compared to when the anode separator 25 and the cathode separator 26 have different configurations.

[0061] <Example of change> The above embodiment can be modified as follows: Furthermore, the above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0062] As shown in FIG. 9, the second rib 29 may be configured to have a semicircular shape in cross section. 10, two second ribs 29 may be provided side by side in the Y-axis direction on the first rib 28. Alternatively, three or more second ribs 29 may be provided side by side in the Y-axis direction on the first rib 28.

[0063] 11, the second rib 29A may be configured to extend linearly in the X-axis direction. Alternatively, the second rib 29B may be configured to extend linearly in the X-axis direction. In either case, the second rib 29A and the second rib 29B extend so as to intersect with each other when viewed from the stacking direction Z.

[0064] 12, the second rib 29A may be configured to extend linearly in the X-axis direction, and the second rib 29B may be configured to extend zigzag in the X-axis direction. Alternatively, the second rib 29B may be configured to extend linearly in the X-axis direction, and the second rib 29A may be configured to extend zigzag in the X-axis direction. In either case, the second ribs 29A and 29B extend so as to intersect with each other when viewed from the stacking direction Z.

[0065] 13, the second ribs 29A and 29B may extend in the X-axis direction in a wavy, meandering pattern with different amplitudes and wavelengths. In this case, the second ribs 29A and 29B extend so as to intersect with each other when viewed from the stacking direction Z.

[0066] 14, the second ribs 29A and 29B may both be configured to extend in a zigzag pattern in the X-axis direction. In this case, the second ribs 29A and 29B extend so as to intersect with each other when viewed from the stacking direction Z.

[0067] 15, the second rib 29A may be configured to extend in the X-axis direction while meandering in a rectangular wave (square wave) pattern, and the second rib 29B may be configured to extend linearly in the X-axis direction. Alternatively, the second rib 29B may be configured to extend in the X-axis direction while meandering in a rectangular wave (square wave) pattern, and the second rib 29A may be configured to extend linearly in the X-axis direction. In either case, the second ribs 29A and 29B extend so as to intersect with each other when viewed from the stacking direction Z.

[0068] As shown in FIG. 16, the second ribs 29A and 29B may extend linearly and intersect with each other at one point when viewed from the stacking direction Z. In the fuel cell 12, the anode separator 25 and the cathode separator 26 may have different configurations.

[0069] The second extending portions Tg1 and Tg2 may extend in the Y-axis direction perpendicular to the X-axis direction in which the first extending portions Lg1 to Lg3 extend, that is, in the direction in which the virtual axis V extends. The second extending portions Tg1 and Tg2 may extend in a wavy, meandering manner.

[0070] The reactant gas supply system in the fuel cell stack 11 may be a so-called co-flow system in which the fuel gas and the oxidant gas flow in the same direction in the first extending portions Lg1 to Lg3.

[0071] The first extending portions Lg1 to Lg3 may extend linearly in the X-axis direction. <Additional Notes> The above embodiment includes the configurations described in the following supplementary notes.

[0072] [Appendix 1] A fuel cell comprising a power generation section including a membrane electrode assembly and a pair of gas diffusion layers sandwiching the membrane electrode assembly, and a pair of separators sandwiching the power generation section, wherein a gas flow path through which a reactant gas flows is provided on a surface of the separator facing the power generation section, the gas flow path having a plurality of first extension parts extending in a first direction and arranged in parallel in an orthogonal direction perpendicular to the first direction, and a second extension part connected to an end of the first extension part in the first direction and extending in a second direction different from the first direction, the flow directions of the reactant gas between the first extension parts adjacent to each other in the orthogonal direction are opposite to each other, and the second extension part is arranged in parallel in the orthogonal direction a first rib that separates the first extension portions adjacent in the perpendicular direction and extends in the first direction is provided between the first extension portions adjacent in the perpendicular direction, a second rib that extends in the first direction is provided on the first rib, and the second rib of one of the pair of separators and the second rib of the other separator extend so as to intersect with each other when viewed from a direction in which the pair of separators sandwich the power generation unit.

[0073] [Appendix 2] The fuel cell according to [Appendix 1], wherein the first extension portion extends in the first direction while meandering in a wave-like manner. [Appendix 3] A fuel cell according to [Appendix 1] or [Appendix 2], characterized in that the second ribs of the pair of separators both extend in the first direction in a wavy, meandering manner, and the second rib of one of the pair of separators and the second rib of the other of the pair of separators are out of phase with each other when viewed from the direction in which the pair of separators sandwich the power generation section.

[0074] [Appendix 4] The fuel cell according to any one of [Appendix 1] to [Appendix 3], wherein the pair of separators have the same configuration. [Explanation of symbols]

[0075] 11...Fuel cell stack 12...Fuel cell 13...First side 14...Second side 15...Power generation section 16...Frame 17...Separator 18...Membrane electrode assembly 19...Anode side gas diffusion layer 20...Cathode side gas diffusion layer 21...Cooling channel 22...Housing hole 23…Groove 24...Gas flow path 25...Anode separator 26...Cathode separator 27...Ribs 28...First rib 29, 29A, 29B...Second rib 30…Cooling groove hf1~hf6…Through hole hs1~hs6…Through hole Lg1~Lg3…First extension part M1...Fuel gas supply manifold M2: Fuel gas discharge manifold M3...Oxidant gas supply manifold M4...Oxidant gas discharge manifold M5... Refrigerant supply manifold M6...Refrigerant discharge manifold R...High compression area Tg1,Tg2…Second extension part V: Virtual axis Z…Stacking direction

Claims

1. A fuel cell comprising: a power generation section including a membrane electrode assembly and a pair of gas diffusion layers sandwiching the membrane electrode assembly; and a pair of separators sandwiching the power generation section, a gas flow channel through which a reactant gas flows is provided on a surface of the separator facing the power generation section; the gas flow path includes a plurality of first extension portions that extend in a first direction and are arranged in parallel in an orthogonal direction that is orthogonal to the first direction, and second extension portions that are connected to ends of the first extension portions in the first direction and extend in a second direction that is different from the first direction, the first extension portions are arranged such that the flow directions of the reactant gas between the first extension portions adjacent to each other in the orthogonal direction are opposite to each other; The second extension portion connects a downstream end of one of the first extension portions adjacent to each other in the orthogonal direction in the flow direction to an upstream end of the other of the first extension portions, a first rib is provided between the first extension portions adjacent to each other in the orthogonal direction, the first rib separating the first extension portions adjacent to each other in the orthogonal direction and extending in the first direction; a second rib extending in the first direction is provided on the first rib; A fuel cell characterized in that, of the pair of separators, the second rib of one separator and the second rib of the other separator extend so as to intersect with each other when viewed from the direction in which the pair of separators sandwich the power generation section.

2. 2. The fuel cell according to claim 1, wherein the first extension portion extends in the first direction in a wavy, meandering manner.

3. The second ribs of the pair of separators both extend in the first direction while meandering in a wavy manner, 3. The fuel cell according to claim 1, wherein the second rib of one of the pair of separators and the second rib of the other of the pair of separators are out of phase with each other when viewed from the direction in which the pair of separators sandwich the power generation section.

4. 3. The fuel cell according to claim 1, wherein the pair of separators have the same configuration.

Images