Single cell of fuel cell

Abstract

A single cell of a fuel cell is provided with a power generation unit and a pair of separators. Each of the separators has a surface facing the power generation unit, and the surface is provided with a gas flow path. The gas flow path has a plurality of first extension portions and second extension portions. The second extension portion connects the downstream-side end portion of one of the adjacent first extension portions and the upstream-side end portion of the other of the adjacent first extension portions. A first rib is provided between adjacent first extension portions. A second rib is provided on the first rib. The second rib of one of the pair of separators and the second rib of the other of the pair of separators extend so as to intersect each other when viewed from a direction in which the power generation unit is sandwiched between the pair of separators.

Description

Technical Field

[0001] The present disclosure relates to a single cell of a fuel cell. Background Art

[0002] Generally, a fuel cell includes a cell stack formed by laminating a plurality of single cells and a pair of end plates that sandwich the cell stack in the lamination direction of the single cells. As a single cell of a fuel cell, for example, a single cell disclosed in Japanese Unexamined Patent Application Publication No. 2013-69541 is currently known. Such a single cell includes a membrane electrode assembly and a pair of separators that sandwich the membrane electrode stack, and is integrally formed in a rectangular plate shape. A pair of gas diffusion layers are disposed between the membrane electrode stack and the pair of separators.

[0003] Gas flow paths for allowing reaction gases to flow are formed on the surfaces of the separators on the side of the membrane electrode stack. These gas flow paths are constituted by recesses formed by stamping. The gas flow path of one of the pair of separators is formed into a so-called serpentine flow path that meanders and extends by being separated by a plurality of ribs extending linearly. In the case where the gas flow path is a serpentine flow path, so-called pass cut may occur in a region of the gas diffusion layer that abuts against the rib, where the reaction gas passes through the pores of the gas diffusion layer and penetrates through the rib.

[0004] Therefore, in order to suppress the occurrence of such pass cut, protrusions extending linearly along the rib are formed on a part of the rib. The protrusions are recessed into the gas diffusion layer in a state of protruding from the rib toward the gas diffusion layer. Therefore, since the gas diffusion layer is locally compressed by the protrusions, the pores through which the reaction gas can permeate are reduced at the portions where the protrusions are recessed. Thereby, the occurrence of the above-mentioned pass cut is suppressed in the portion of the gas diffusion layer compressed by the protrusions. Summary of the Invention

[0005] Problems to be Solved by the Invention

[0006] However, in the above-mentioned single cell, in the case where the gas flow paths of the two separators in the pair of separators are serpentine flow paths, if protrusions are formed on the ribs as described above to suppress the occurrence of the above-mentioned pass cut, there will be the following problems.

[0007] When the pair of gas diffusion layers are sandwiched by the pair of separators, the protrusions of one of the pair of separators overlap with the protrusions of the other separator when viewed from the direction in which the pair of separators sandwich the membrane electrode stack. In this case, since each protrusion extends linearly, when the positions of the pair of separators are offset from each other in a direction orthogonal to the above-mentioned sandwiching direction, the protrusions of the pair of separators may sometimes not overlap with each other at all when viewed from the above-mentioned sandwiching direction.

[0008] Therefore, when manufacturing a plurality of single cells, single cells are manufactured in which the protrusions of a pair of separators completely overlap each other or do not overlap at all when viewed from the above-mentioned clamping direction. In this case, between the plurality of single cells, when the protrusions of the pair of separators completely overlap each other and when they do not overlap at all when viewed from the above-mentioned clamping direction, there is a large difference in the compression rate of the protrusions of the pair of separators against a pair of gas diffusion layers.

[0009] As a result, there is a problem that the deviation of the pressure loss of the reaction gas flowing in the gas diffusion layer becomes large between the plurality of single cells constituting the fuel cell.

[0010] Solution to the problem

[0011] A single cell of a fuel cell according to an aspect of the present disclosure includes a power generation unit and a pair of separators that sandwich the power generation unit. The power generation unit includes a membrane electrode assembly and a pair of gas diffusion layers that sandwich the membrane electrode assembly. Each separator has a surface facing the power generation unit, and a gas flow path configured to allow a reaction gas to flow is provided on the surface facing the power generation unit. The gas flow path has: a plurality of first extension portions extending along a first direction and arranged in parallel in an orthogonal direction orthogonal to the first direction; and a second extension portion connected to an end of the first extension portion in the first direction and extending along a second direction different from the first direction. Among the plurality of first extension portions, the flow directions of the reaction gas of the first extension portions adjacent to each other in the orthogonal direction are opposite to each other. The second extension portion connects the end portion on the downstream side in the flow direction of one of the first extension portions adjacent to each other in the orthogonal direction to the end portion on the upstream side in the flow direction of the other first extension portion. A first rib that separates the first extension portions adjacent to each other in the orthogonal direction and extends along the first direction is provided between the first extension portions adjacent to each other in the orthogonal direction. A second rib extending along the first direction is provided on the first rib. The second rib of one of the pair of separators and the second rib of the other separator extend crosswise when viewed from the direction in which the pair of separators sandwich the power generation unit. Description of the drawings

[0012] Figure 1 is a cross-sectional view showing a fuel cell stack according to an embodiment.

[0013] Figure 2 is showing Figure 1 exploded perspective view of the single cell.

[0014] Figure 3 is showing Figure 1Top view of the gas flow path of the separator.

[0015] Figure 4 is Figure 3 An enlarged view of the main part of

[0016] Figure 5 is Figure 4 Schematic view of the sectional view taken along line 5-5 of

[0017] Figure 6 represents Figure 1 Top view schematic of a part of a single cell of

[0018] Figure 7 represents Figure 1 Cross-sectional view of the main part of a single cell of

[0019] Figure 8 represents Figure 1 Cross-sectional view of the main part of a single cell of

[0020] Figure 9 Schematic sectional view of the second rib of the modification example

[0021] Figure 10 Schematic sectional view of the second rib of the modification example

[0022] Figure 11 Top view schematic showing the overlapping state of the second ribs of a pair of separators of a single cell of the modification example

[0023] Figure 12 Top view schematic showing the overlapping state of the second ribs of a pair of separators of a single cell of the modification example

[0024] Figure 13 Top view schematic showing the overlapping state of the second ribs of a pair of separators of a single cell of the modification example

[0025] Figure 14 Top view schematic showing the overlapping state of the second ribs of a pair of separators of a single cell of the modification example

[0026] Figure 15 Top view schematic showing the overlapping state of the second ribs of a pair of separators of a single cell of the modification example

[0027] Figure 16 Top view schematic showing the overlapping state of the second ribs of a pair of separators of a single cell of the modification example Detailed implementation mode

[0028] Hereinafter, an embodiment will be described with reference to the accompanying drawings.

[0029] <Fuel cell stack 11>

[0030] As Figure 1 shown, the fuel cell stack 11 is formed by stacking a plurality of single cells 12.

[0031] <Single cell 12>

[0032] As Figure 2 shown, the single cell 12 is formed, for example, in the shape of a square plate. That is, the single cell 12 has a pair of first sides 13 extending parallel to each other and a pair of second sides 14 orthogonal to the first sides 13 and extending parallel to each other.

[0033] Hereinafter, the stacking direction Z of the single cell 12 will be simply referred to as the stacking direction Z for explanation. In addition, 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 for explanation. The stacking direction Z, the X-axis direction, and the Y-axis direction are orthogonal to each other.

[0034] The single cell 12 has a fuel gas supply manifold M1 for supplying fuel gas to the inside of the single cell 12 and a fuel gas discharge manifold M2 for discharging fuel gas to the outside of the single cell 12. The single cell 12 has an oxidant gas supply manifold M3 for supplying oxidant gas to the inside of the single cell 12 and an oxidant gas discharge manifold M4 for discharging oxidant gas to the outside of the single cell 12.

[0035] The manifolds M1 to M4 are formed, for example, in an oval shape that is 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 single cell 12 in the X-axis direction and are arranged in order from one side to the other side in the Y-axis direction.

[0036] The fuel gas discharge manifold M2 and the oxidant gas supply manifold M3 are located at the other end of the single cell 12 in the X-axis direction, which is the opposite side of the one side, and are arranged in order from the other side to the one side in the Y-axis direction. The fuel gas is, for example, hydrogen. The oxidant gas is, for example, air.

[0037] As Figure 1 and Figure 2 shown, the single cell 12 has two refrigerant supply manifolds M5 for supplying a cooling medium to the inside of the fuel cell stack 11 and two refrigerant discharge manifolds M6 for discharging the cooling medium to the outside of the fuel cell stack 11. Each refrigerant supply manifold M5 and each refrigerant discharge manifold M6 are formed, for example, in an oval shape that is long in the X-axis direction.

[0038] Two refrigerant supply manifolds M5 are located at the ends on the other side in the Y-axis direction of the single cell 12, and are arranged at intervals in the X-axis direction. Two refrigerant discharge manifolds M6 are located at the ends on one side in the Y-axis direction of the single cell 12, and are arranged at intervals in the X-axis direction. The cooling medium is, for example, water.

[0039] The single cell 12 includes a power generation part 15, a frame 16, and a pair of separators 17. The power generation part 15 is formed in a sheet shape. The frame 16 surrounds the outer peripheral edge of the power generation part 15. The pair of separators 17 sandwich the power generation part 15 and the 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 part 15". The power generation part 15 and the separators 17 are, for example, formed in a square shape in a plan view. The frame 16 is, for example, formed in a square frame shape in a plan view.

[0040] <Power generation part 15>

[0041] As Figure 1 shown, the power generation part 15 includes a membrane electrode assembly 18, an anode-side gas diffusion layer 19 that holds the membrane electrode assembly 18, and a cathode-side gas diffusion layer 20. 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". The membrane electrode assembly 18 includes an electrolyte membrane, an anode electrode catalyst layer that holds the electrolyte membrane, and a cathode electrode catalyst layer, which are not shown here. 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.

[0042] The fuel gas is supplied to the anode-side surface of the power generation part 15 through the fuel gas supply manifold M1. The oxidant gas is supplied to the cathode-side surface of the power generation part 15 through the oxidant gas supply manifold M3. Thus, in the power generation part 15, power generation is performed by the electrochemical reaction between the fuel gas and the oxidant gas.

[0043] In the fuel cell stack 11, as the power generation part 15 generates power, each single cell 12 generates heat. Therefore, a cooling flow path 21 described later is formed inside the fuel cell stack 11. The cooling medium is supplied to the cooling flow path 21 through the refrigerant supply manifold M5.

[0044] <Frame 16>

[0045] As Figure 2 shown, the frame 16 is formed of a resin material having insulation properties. The frame 16 has a receiving hole 22 for receiving the power generation part 15 at the central part. The frame 16 has through holes hf1 to hf6 forming the manifolds M1 to M6 on the outer peripheral side of the receiving hole 22. The frame 16 has a plurality of grooves 23 between the receiving hole 22 and each of the through holes hf1 to hf4.

[0046] The multiple slots 23 formed between the accommodation hole 22 and each of the through holes hf1, hf2 and the multiple slots 23 formed between the accommodation hole 22 and each of the through holes hf3, hf4 are arranged on opposite sides of the two surfaces in the stacking direction Z of the frame 16. That is, the multiple slots 23 formed between the accommodation hole 22 and each of the through holes hf1, hf2 are arranged on one of the two surfaces in the stacking direction Z of the frame 16. On the other hand, the multiple slots 23 formed between the accommodation hole 22 and each of the through holes hf3, hf4 are arranged on the other of the two surfaces in the stacking direction Z of the frame 16.

[0047] The multiple slots 23 are juxtaposed at intervals in the Y-axis direction. Each slot 23 is formed in an oval shape that is long in the X-axis direction. One end of each slot 23 communicates with any one of the through holes hs1 to hs4 of a partition member 17 described later in the stacking direction Z. The other end of each slot 23, which is on the side opposite to the one end, communicates with the gas flow path 24 of the partition member 17 described later in the stacking direction Z. Each of the manifolds M1 to M4 communicates with the gas flow path 24 via, for example, seven slots 23.

[0048] <Partition member 17>

[0049] As Figure 1 and Figure 2 shown, the partition member 17 is formed, for example, by stamping a metal plate such as stainless steel or titanium alloy. One of the pair of partition members 17 is arranged on the anode-side surface of the power generation unit 15, and the other is arranged on the cathode-side surface of the power generation unit 15.

[0050] In the following description, the partition member 17 arranged on the anode-side surface of the power generation unit 15 may sometimes be referred to as the anode partition member 25 and the partition member 17 arranged on the cathode-side surface of the power generation unit 15 may be referred to as the cathode partition member 26 for distinction.

[0051] The anode partition member 25 and the cathode partition member 26 have the same structure as each other. The anode partition member 25 and the cathode partition member 26 are arranged in a posture that is flipped relative to the power generation unit 15 with the imaginary axis V as the axis of flipping. The imaginary axis V is an axis that passes through the center in the X-axis direction of the partition member 17 and extends along the Y-axis direction.

[0052] The partition member 17 has through holes hs1 to hs6 that constitute the manifolds M1 to M6. As described above, the anode partition member 25 and the cathode partition member 26 are arranged in a posture that is flipped relative to the power generation unit 15. Therefore, the through hole hs1 of the anode partition member 25 communicates with the through hole hs3 of the cathode partition member 26, and the through hole hs2 of the anode partition member 25 communicates with the through hole hs4 of the cathode partition member 26.

[0053] The through-holes hs3 of the anode separator 25 communicate with the through-holes hs1 of the cathode separator 26, and the through-holes hs4 of the anode separator 25 communicate with the through-holes hs2 of the cathode separator 26. The through-holes hs5 of the anode separator 25 communicate with the through-holes hs5 of the cathode separator 26, and the through-holes hs6 of the anode separator 25 communicate with the through-holes hs6 of the cathode separator 26.

[0054] As Figure 3 shown, groove-shaped gas flow paths 24 for the flow of reaction gas and ribs 27 extending along the gas flow paths 24 are provided in an alternating arrangement on the surface of the separator 17 facing the power generation unit 15. The separator 17 has, for example, eight gas flow paths 24 extending side by side. The shape of each gas flow path 24 is a so-called serpentine shape that extends in a meandering manner from the through-hole hs1 toward the through-hole hs2.

[0055] As Figure 2 and Figure 3 shown, fuel gas flows as the reaction gas in the gas flow paths 24 of the anode separator 25. Oxidant gas flows as the reaction gas in the gas flow paths 24 of the cathode separator 26. The reaction gas is supplied to the power generation unit 15 by flowing in the gas flow paths 24. The supply mode of the reaction gas in the fuel cell stack 11 is, for example, a so-called counterflow mode in which the fuel gas and the oxidant gas flow in opposite directions.

[0056] Hereinafter, the upstream side in the flow direction of the reaction gas in the gas flow path 24 will be simply referred to as the upstream side, and the downstream side in this flow direction will be simply referred to as the downstream side for explanation.

[0057] 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 reaction gas sequentially flows in 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. The first extension portions Lg1 to Lg3 are arranged side by side adjacent to each other in the Y-axis direction. The first extension portions Lg1 to Lg3 extend along the X-axis direction while meandering in a wave shape. The X-axis direction is an example of the "first direction". The Y-axis direction orthogonal to the X-axis direction is an example of the "orthogonal direction".

[0058] The second extension portions Tg1 and Tg2 extend linearly in an inclined manner with respect to the imaginary axis V so as to be located on one side in the X-axis direction as they go toward the downstream side. The extending direction of the second extension portions Tg1 and Tg2 is an example of a "second direction" different from the above "first direction".

[0059] The end portion on the upstream side of the first extension part Lg1 is connected to the through hole hs1 via the groove 23 of the frame 16. The second extension part Tg1 connects the end portion on the downstream side of the first extension part Lg1 to the end portion on the upstream side of the first extension part Lg2. The second extension part Tg2 connects the end portion on the downstream side of the first extension part Lg2 to the end portion on the upstream side of the first extension part Lg3. The end portion on the downstream side of the first extension part Lg3 is connected to the through hole hs2 via the groove 23.

[0060] When the reaction gas flows from the first extension part Lg1 to the first extension part Lg2 via the second extension part Tg1 and when it flows from the first extension part Lg2 to the first extension part Lg3 via the second extension part Tg2, the flow direction of the reaction gas is reversed. Thus, the second extension parts Tg1 and Tg2 constitute the folded-back portions of the gas flow path 24. Among the first extension part Lg1, the first extension part Lg3, and the first extension part Lg2 that are adjacent to each other in the Y-axis direction, the flow directions of the reaction gas are in directions opposite to each other in the X-axis direction.

[0061] As Figures 3 to 5 shown, first ribs 28 extending along the X-axis direction are respectively provided between the first extension part Lg1 and the first extension part Lg2 adjacent to each other in the Y-axis direction and between the first extension part Lg2 and the first extension part Lg3 adjacent to each other in the Y-axis direction. The first rib 28 provided between the first extension part Lg1 and the first extension part Lg2 separates the first extension part Lg1 and the first extension part Lg2. The first rib 28 provided between the first extension part Lg2 and the first extension part Lg3 separates the first extension part Lg2 and the first extension part Lg3.

[0062] The first rib 28 that separates the first extension part Lg1 and the first extension part Lg2 extends along the X-axis direction while meandering in a wave shape along the first extension part Lg1 and the first extension part Lg2. The first rib 28 that separates the first extension part Lg2 and the first extension part Lg3 extends along the X-axis direction while meandering in a wave shape along the first extension part Lg2 and the first extension part Lg3.

[0063] A second rib 29 is provided on the first rib 28. The second rib 29 is disposed at the central portion in the width direction on the first rib 28 and extends along the X-axis direction while meandering in a wave shape along the first rib 28. The second rib 29 extends over substantially the whole of the first rib 28 in the X-axis direction. The first rib 28 and the second rib 29 are each formed in a substantially trapezoidal shape in a cross-sectional view, for example.

[0064] In the following description, the second rib 29 of the anode separator 25 may sometimes 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.

[0065] As Figure 6As shown, among a pair of separators 17 of the single cell 12, the second rib 29A of the anode separator 25 on one side and the second rib 29B of the cathode separator 26 on the other side extend crossing each other when viewed from the stacking direction Z. That is, the phases of the second rib 29A and the second rib 29B in the X-axis direction are shifted from each other when viewed from the stacking direction Z. Therefore, assuming that the second rib 29A and the second rib 29B are lines, the second rib 29A and the second rib 29B intersect at a point when viewed from the stacking direction Z but do not continuously overlap within a range exceeding a certain length.

[0066] <Cooling flow path 21>

[0067] As Figure 1 shown, in the fuel cell stack 11, the anode separator 25 of one of the two single cells 12 adjacent in the stacking direction Z and the cathode separator 26 of the other single 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 among the two single cells 12 adjacent in the stacking direction Z. A gasket for sealing between the two single cells 12 is provided between the mutually contacting anode separator 25 and cathode separator 26, and illustration thereof is omitted.

[0068] As Figure 1 and Figure 2 shown, the separator 17 has a plurality of cooling grooves 30 that constitute the cooling flow path 21. The cooling grooves 30 are formed on the surface of the separator 17 opposite to the surface where the gas flow path 24 is formed. The cooling grooves 30 are formed by the back surface shape of the ribs 27. The shape of the cooling grooves 30 is a serpentine shape that extends in a meandering manner from the through-hole hs1 toward the through-hole hs2.

[0069] The cooling flow path 21 is constituted by the gap between the cooling grooves 30 of the anode separator 25 and the cooling grooves 30 of the cathode separator 26. The cooling medium supplied from the refrigerant supply manifold M5 flows through the cooling flow path 21 and is discharged from the refrigerant discharge manifold M6.

[0070] <Functions of the embodiment>

[0071] As Figure 7As shown, in the single cell 12, the second rib 29A of the anode separator 25 sinks into the anode-side gas diffusion layer 19, and the second rib 29B of the cathode separator 26 sinks into the cathode-side gas diffusion layer 20. In the gas diffusion layers 19 and 20, the regions where the second ribs 29A and 29B are sunken are compressed, so the pressure loss during the flow of the reaction gas becomes larger compared to other regions. Therefore, it is possible to suppress the reaction gas from flowing across the first rib 28 without passing through the second extension part Tg1 and the second extension part Tg2 between the first extension parts Lg1 and Lg2 adjacent to each other in the Y-axis direction and between the first extension parts Lg2 and Lg3 respectively.

[0072] In this case, as Figure 6 shown, both the second ribs 29A and 29B are wavy and meandering and extend along the X-axis direction at the same time, and extend crossing each other when observed from the stacking direction Z. Also, the positions of the second ribs 29A and 29B relative to each other may be slightly offset in a direction orthogonal to the stacking direction Z, such as the X-axis direction or the Y-axis direction, due to errors during the assembly of the single cell 12.

[0073] Here, as Figure 8 shown, in the gas diffusion layers 19 and 20, the region where the second ribs 29A and 29B overlap each other when observed from the stacking direction Z is compressed from both sides in the stacking direction Z by the second ribs 29A and 29B, and thus becomes a high-compression region R where the compression ratio becomes extremely high. In the high-compression region R, the pressure loss during the flow of the reaction gas becomes extremely high.

[0074] Therefore, when the high-compression region R is continuously formed in the gas diffusion layers 19 and 20 within a range of a certain length or more, the pressure loss during the flow of the reaction gas becomes large for the single cell 12. On the other hand, as Figure 7 shown, when the high-compression region R is not continuously formed in the gas diffusion layers 19 and 20 within a range of a certain length or more, the pressure loss during the flow of the reaction gas is suppressed to be small for the single cell 12.

[0075] Moreover, between the multiple single cells 12 constituting the fuel cell stack 11, if the deviation of the pressure loss during the flow of the reaction gas becomes large, the deviation of the amount of the flowing reaction gas also becomes large. Therefore, there is a risk that the power generation performance of the fuel cell stack 11 decreases.

[0076] In view of this, in the single cell 12 of the present embodiment, regardless of whether the positions of the second ribs 29A and 29B are offset from each other in the direction orthogonal to the stacking direction Z or not, they overlap continuously within a range where they overlap at a point but not by more than a certain length when viewed from the stacking direction Z. That is, in the single cell 12 of the present embodiment, regardless of whether the positions of the second ribs 29A and 29B are offset from each other in the direction orthogonal to the stacking direction Z or not, a highly compressed region R is not continuously formed in the gas diffusion layers 19 and 20 within a range of more than a certain length.

[0077] That is, in the single cell 12 of the present embodiment, regardless of whether the positions of the second ribs 29A and 29B are offset from each other in the direction orthogonal to the stacking direction Z or not, the pressure loss of the reaction gas flowing in the gas diffusion layers 19 and 20 hardly changes. Therefore, the deviation of the pressure loss when the reaction gas flows between the multiple single cells 12 constituting the fuel cell stack 11 is reduced, and thus the deviation of the amount of the reaction gas flowing is also reduced. As a result, the risk of reduction in the power generation performance of the fuel cell stack 11 is reduced.

[0078] <Effect of the Embodiment>

[0079] According to the embodiment described in detail above, the following effects can be achieved.

[0080] (1) In the single cell 12, the second rib 29A of the anode separator 25 and the second rib 29B of the cathode separator 26 extend crossing each other when viewed from the stacking direction Z.

[0081] According to the above structure, under the action of the above-described embodiment, the deviation of the pressure loss when the reaction gas flows can be reduced between the multiple single cells 12 constituting the fuel cell stack 11, and thus the deviation of the amount of the reaction gas flowing can also be reduced. Therefore, the risk of reduction in the power generation performance of the fuel cell stack 11 can be reduced.

[0082] (2) In the single cell 12, the first extension portions Lg1 to Lg3 extend along the X-axis direction while meandering in a wave shape.

[0083] According to the above structure, when multiple single cells 12 are stacked to form the fuel cell stack 11, compared with the case where the first extension portions Lg1 to Lg3 extend linearly along the X-axis direction, the cooling medium can flow smoothly in the cooling flow paths 21 between the single cells 12 adjacent to each other in the stacking direction Z.

[0084] (3) In the single cell 12, the second rib 29A of the anode separator 25 and the second rib 29B of the cathode separator 26 both extend along the X-axis direction while meandering in a wave shape. The second rib 29A and the second rib 29B are out of phase with each other when viewed from the stacking direction Z.

[0085] According to the above structure, by extending the second ribs 29A and 29B in a wavy meandering manner along the first extensions Lg1 to Lg3 of the gas flow path 24 in the X-axis direction, unnecessary space is less likely to be generated. Therefore, the space of the single cell 12 can be effectively utilized, and thus the miniaturization of the single cell 12 can be facilitated. In addition, since the second ribs 29A and 29B are out of phase with each other when viewed from the stacking direction Z, the same effect as the above (1) can be obtained.

[0086] (4) In the single cell 12, the anode separator 25 and the cathode separator 26 have the same structure as each other.

[0087] According to the above structure, compared with the case where the anode separator 25 and the cathode separator 26 have different structures from each other, the number of components constituting the single cell 12 can be reduced.

[0088] <Change Example>

[0089] The above-described embodiment can be implemented with the following changes. In addition, the above-described embodiment and the following change examples can be implemented in combination with each other within a range where there is no technical contradiction.

[0090] · As Figure 9 shown, the second rib 29 may be configured to be, for example, semicircular in a cross-sectional view.

[0091] · As Figure 10 shown, the second rib 29 may be provided on the first rib 28 in such a manner that two are arranged in the Y-axis direction. Alternatively, the second rib 29 may be provided on the first rib 28 in such a manner that three or more are arranged in the Y-axis direction.

[0092] · As Figure 11 shown, 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 crossing each other when viewed from the stacking direction Z.

[0093] · As Figure 12 shown, 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 in a zigzag manner 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 in a zigzag manner in the X-axis direction. In either case, the second rib 29A and the second rib 29B extend crossing each other when viewed from the stacking direction Z.

[0094] · As Figure 13As shown, the second ribs 29A and 29B may also extend along the X-axis direction while meandering in waveforms with different amplitudes and wavelengths. In this case, the second ribs 29A and 29B extend crossing each other when viewed from the stacking direction Z.

[0095] · As Figure 14 shown, the second ribs 29A and 29B may also be configured to extend in a zigzag shape along the X-axis direction. In this case, the second ribs 29A and 29B extend crossing each other when viewed from the stacking direction Z.

[0096] · As Figure 15 shown, the second rib 29A may be configured to extend along the X-axis direction while meandering in a rectangular wave (square wave) shape, and the second rib 29B may be configured to extend linearly along the X-axis direction. Alternatively, the second rib 29B may be configured to extend along the X-axis direction while meandering in a rectangular wave (square wave) shape, and the second rib 29A may be configured to extend linearly along the X-axis direction. In either case, the second ribs 29A and 29B extend crossing each other when viewed from the stacking direction Z.

[0097] · As Figure 16 shown, the second ribs 29A and 29B may also cross each other at a point and extend linearly when viewed from the stacking direction Z.

[0098] · In the single cell 12, the anode separator 25 and the cathode separator 26 may also have different structures from each other.

[0099] · The second extension parts Tg1, Tg2 may also extend along the Y-axis direction orthogonal to the X-axis direction in which the first extension parts Lg1 to Lg3 extend, that is, the direction in which the imaginary axis V extends.

[0100] · The second extension parts Tg1, Tg2 may also extend while meandering in a waveform.

[0101] · The supply mode of the reaction gas in the fuel cell stack 11 may also be a so-called coflow mode in which the fuel gas and the oxidant gas flow in the same direction in the first extension parts Lg1 to Lg3.

[0102] · The first extension parts Lg1 to Lg3 may also extend linearly along the X-axis direction.

Claims

1. A single cell of a fuel cell, wherein, the single cell of the fuel cell includes a power generation part and a pair of separators sandwiching the power generation part, and the power generation part includes a membrane electrode assembly and a pair of gas diffusion layers sandwiching the membrane electrode assembly, each separator has a surface facing the power generation part, and a gas flow path configured for a reaction gas to flow is provided on the surface facing the power generation part, the gas flow path has: a plurality of first extension parts extending along a first direction and arranged in parallel in an orthogonal direction orthogonal to the first direction; and a second extension part connected to an end of the first extension part in the first direction and extending along a second direction different from the first direction, among the plurality of first extension parts, the flow directions of the reaction gas of the first extension parts adjacent to each other in the orthogonal direction are opposite to each other, the second extension part connects the end of one of the first extension parts located on the downstream side in the flow direction to the end of the other first extension part located on the upstream side in the flow direction among the first extension parts adjacent to each other in the orthogonal direction, a first rib extending along the first direction and separating the first extension parts adjacent to each other in the orthogonal direction is provided between the first extension parts adjacent to each other in the orthogonal direction, a second rib extending along the first direction is provided on the first rib, the second rib of one of the pair of separators and the second rib of the other separator extend crosswise when observed from the direction in which the pair of separators sandwich the power generation part.

2. The single cell of the fuel cell according to claim 1, wherein, the first extension part extends along the first direction while being wavy and meandering.

3. The single cell of the fuel cell according to claim 1 or 2, wherein, the second ribs of the pair of separators both extend along the first direction while being wavy and meandering, the second rib of one of the pair of separators and the second rib of the other separator are out of phase when observed from the direction in which the pair of separators sandwich the power generation part.

4. The single cell of the fuel cell according to claim 1 or 2, wherein, the pair of separators have the same structure as each other.

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