Fuel battery cell

Abstract

To provide a fuel battery cell capable of efficiently supplying a power generation part with reaction gas from a gas flow passage.SOLUTION: A fuel battery cell 12 includes a power generation part 15 and a pair of separators 17 with the power generation part 15 in between. An opposite surface 26 facing the power generation part 15 in the separator 17 is provided with: a gas flow passage 27 into which reaction gas flows; and a rib 28. The gas flow passage 27 has: a mesh-like part 29 which is formed into a mesh in an area corresponding to the power generation part 15 on the opposite surface 26; an inflow part 30 which is connected to one end part in an X axial direction in the mesh-like part 29 and flows the reaction gas into the mesh-like part 29; and an outflow part 31 which is connected to the other end in the X axial direction in the mesh-like part 29 and flows the reaction gas out of the mesh-like part 29. Meshes of the mesh-like part 29 are composed of ribs 28. Lengths of the plurality of ribs 28 in the X axial direction composing the meshes become gradually shorter every rib 28 from the inflow part 30 side to the outflow part 31 side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, a known fuel cell is shown in, for example, Patent Document 1. Such a fuel cell has a configuration in which a power generation section supported by a frame member is sandwiched between a pair of separators. Each separator has a groove flow path formed therein for supplying reactant gas to the power generation section. The groove flow path of each separator extends in a wave-like pattern and has a plurality of branch flow paths and a junction where the branch flow paths join from the upstream side to the downstream side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-182065 Summary of the Invention [Problem to be solved by the invention]

[0004] In the fuel cell described above, the groove flow paths of each separator are configured as described above, but there is still room for improvement in terms of efficiently supplying the reactant gas to the power generation section. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. A fuel cell that solves the above problem is a fuel cell comprising a power generation section including a membrane electrode assembly and a pair of separators sandwiching the power generation section, wherein a gas flow path through which a reactant gas flows and ribs adjacent to the gas flow path are provided on an opposing surface of the separator that faces the power generation section, the gas flow path having a mesh-like portion formed in a region of the opposing surface that corresponds to the power generation section, an inlet portion that is connected to one end of the mesh portion in one direction and causes the reactant gas to flow into the mesh portion, and an outlet portion that is connected to the other end of the mesh portion opposite to the one end in the one direction and causes the reactant gas to flow out of the mesh portion, the mesh of the mesh being formed by the ribs, and the length in one direction of the multiple ribs that constitute the mesh becoming longer or shorter in a stepwise manner for at least one rib from the inlet portion side to the outlet portion side.

[0006] According to the above configuration, the gas flow path has a mesh-like portion, forming multiple junctions where reactant gases converge in a region of the opposing surface corresponding to the power generation unit. In the gas flow path, the pressure loss of the reactant gas downstream of the junction is greater than the pressure loss of the reactant gas upstream of the junction. Therefore, the amount of reactant gas flowing into the power generation unit is greater in the downstream portion of the gas flow path than in the upstream portion of the junction. Additionally, the length of the multiple ribs aligned in one direction gradually increases or decreases for at least one rib from the inlet side to the outlet side. Therefore, when multiple fuel cell units are stacked, each having a configuration in which a pair of separators is inverted so that one end and the other end in one direction are interchanged, the positions of the gas flow paths and the ribs of the separators that contact each other in two adjacent fuel cell units in the stacking direction are offset in one direction. This prevents the irregularities forming the gas flow paths and ribs of the separators that contact each other in two adjacent fuel cell units in the stacking direction from interlocking with each other. This ensures a stable and well-balanced surface pressure on the opposing surface of the separator against the power generation section, improving the adhesion of the opposing surface of the separator to the power generation section, thereby enabling the reactant gas to be efficiently supplied from the gas flow path to the power generation section. [Brief explanation of the drawings]

[0007] [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. 3 is a plan view showing the positional relationship between gas flow channels of a pair of separators. [Figure 5] FIG. 10 is a plan view showing a gas flow path of a separator according to a modified example. [Figure 6] FIG. 10 is a plan view showing a gas flow path of a separator according to a modified example. [Figure 7] FIG. 10 is a plan view showing a gas flow path of a separator according to a modified example. [Figure 8] FIG. 10 is a plan view showing a gas flow path of a separator according to a modified example. [Figure 9] FIG. 10 is a plan view showing a gas flow path of a separator according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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 plate-shaped fuel cells 12.

[0009] <Fuel cell 12> 2, the fuel cell 12 has, for example, a rectangular plate shape. That is, the fuel cell 12 has a pair of long sides 13 extending parallel to each other and a pair of short sides 14 perpendicular to the long sides 13 and extending parallel to each other.

[0010] In the following description, the stacking direction Z, which coincides with the thickness direction of the fuel cell 12, will be simply referred to as the stacking direction Z. The direction in which the long sides 13 extend will be referred to as the X-axis direction, and the direction in which the short sides 14 extend 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.

[0011] 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.

[0012] 1 and 2, the fuel cell 12 has a coolant supply manifold M5 that supplies a coolant to the inside of the fuel cell stack 11, and a coolant discharge manifold M6 that discharges the coolant to the outside of the fuel cell stack 11. The manifolds M1 to M6 are, for example, rectangular in shape.

[0013] 2, the fuel gas supply manifold M1, the coolant supply manifold M5, and the oxidant gas discharge manifold M4 are located at one end of the fuel cell 12 in the X-axis direction, and are arranged in this order from one side to the other in the Y-axis direction. The fuel gas discharge manifold M2, the coolant discharge manifold M6, and the oxidant gas supply manifold M3 are located at the other end of the fuel cell 12 opposite to the one side in the X-axis direction, and are arranged in this 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. The coolant is, for example, water.

[0014] 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 power generation section 15 and separators 17 are, for example, rectangular in plan view. The frame 16 is, for example, rectangular frame-shaped in plan view.

[0015] <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. 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.

[0016] 1 and 2, 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.

[0017] 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.

[0018] <Frame 16> 2, frame 16 is made of an insulating resin material. Frame 16 has a housing hole 22 in the center that houses power generation unit 15. Frame 16 has through holes hf1 to hf6 that form manifolds M1 to M6 on the outer periphery of housing hole 22.

[0019] <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.

[0020] 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 24, and the separator 17 placed on the cathode side of the power generation section 15 may be referred to as a cathode separator 25.

[0021] The anode separator 24 and the cathode separator 25 have the same configuration. The anode separator 24 and the cathode separator 25 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.

[0022] Separator 17 has through holes hs1 to hs6 that form manifolds M1 to M6. As described above, anode separator 24 and cathode separator 25 are disposed in an inverted position relative to power generation section 15. Therefore, through hole hs1 of anode separator 24 and through hole hs3 of cathode separator 25 communicate with each other, and through hole hs2 of anode separator 24 and through hole hs4 of cathode separator 25 communicate with each other.

[0023] The through hole hs3 of the anode separator 24 and the through hole hs1 of the cathode separator 25 are in communication with each other, and the through hole hs4 of the anode separator 24 and the through hole hs2 of the cathode separator 25 are in communication with each other. The through hole hs5 of the anode separator 24 and the through hole hs6 of the cathode separator 25 are in communication with each other, and the through hole hs6 of the anode separator 24 and the through hole hs5 of the cathode separator 25 are in communication with each other.

[0024] 2 and 3, the opposing surface 26 of the separator 17 facing the power generation section 15 is provided with groove-shaped gas flow paths 27 through which the reactant gas flows, and ribs 28 adjacent to the gas flow paths 27. The gas flow paths 27 have a mesh-like section 29, an inlet section 30 through which the reactant gas flows into the mesh section 29, and an outlet section 31 through which the reactant gas flows out of the mesh section 29.

[0025] The mesh portion 29 of the gas flow path 27 is formed in a region of a substantially rectangular shape in plan view on the opposing surface 26 that corresponds to the power generation section 15. The mesh of the mesh portion 29 is formed by ribs 28. Therefore, in the mesh portion 29, the gas flow path 27 extends so as to surround the multiple ribs 28. That is, in the mesh portion 29, the gas flow path 27 extends along the outlines of the multiple ribs 28. In this example, the ribs 28 have a hexagonal shape in plan view. The mesh portion 29 of the gas flow path 27 has multiple branch portions 32 that branch from one flow path into two flow paths, and multiple junction portions 33 that join the two flow paths into one flow path.

[0026] The multiple ribs 28 that make up the mesh of the mesh portion 29 are arranged side by side in the X-axis direction and the Y-axis direction. The X-axis direction is an example of "one direction." The Y-axis direction is an example of "a direction perpendicular to one direction." The length L in the X-axis direction of the multiple ribs 28 that make up the mesh of the mesh portion 29 and are arranged side by side in the X-axis direction gradually decreases for each rib 28 from the inlet portion 30 side to the outlet portion 31 side.

[0027] 3, if the multiple ribs 28 aligned in the X-axis direction are rib 28A, rib 28B, rib 28C, rib 28D, and rib 28E in that order from inlet portion 30 to outlet portion 31, the relationship in magnitude of their lengths L in the X-axis direction is rib 28A > rib 28B > rib 28C > rib 28D > rib 28E. The width H in the Y-axis direction of rib 28 is preferably 2 mm or less, and more preferably 1.5 mm or less.

[0028] The inlet section 30 is connected to one end of the mesh section 29 in the X-axis direction, and the outlet section 31 is connected to the other end of the mesh section 29 opposite to the one end in the X-axis direction. Both the inlet section 30 and the outlet section 31 are configured with a plurality of flow paths (six in this example) that extend linearly in the X-axis direction and are arranged parallel to and equally spaced apart in the Y-axis direction. The plurality of flow paths that make up the inlet section 30 are longer in the X-axis direction than the plurality of flow paths that make up the outlet section 31.

[0029] 2 and 4, when the fuel cell 12 is viewed from the stacking direction Z, the mesh portion 29 and ribs 28 of the gas flow passage 27 of the anode separator 24 and the mesh portion 29 and ribs 28 of the gas flow passage 27 of the cathode separator 25 are misaligned in the X-axis direction. In Fig. 4, the gas flow passage 27 of the anode separator 24 is indicated by a solid line, and the gas flow passage 27 of the cathode separator 25 is indicated by a two-dot chain line.

[0030] 2 and 3, the ends of the multiple flow paths constituting the inlet section 30 opposite the mesh section 29 side are connected to the through-hole hs1 via multiple upstream connecting flow paths 34. The ends of the multiple flow paths constituting the outlet section 31 opposite the mesh section 29 side are connected to the through-hole hs2 via multiple downstream connecting flow paths 35.

[0031] A fuel gas flows as a reactant gas through the gas flow passage 27 of the anode separator 24. An oxidant gas flows as a reactant gas through the gas flow passage 27 of the cathode separator 25. The reactant gas flows through the gas flow passage 27 and is supplied to the power generation unit 15.

[0032] <Cooling channel 21> As shown in Figure 1, in the fuel cell stack 11, of two adjacent fuel cell cells 12 in the stacking direction Z, the anode separator 24 constituting one fuel cell cell 12 and the cathode separator 25 constituting the other fuel cell 12 are in contact with each other.

[0033] A cooling flow path 21 through which a cooling medium flows is formed between the anode separator 24 and the cathode separator 25 that contact each other in two adjacent fuel cell units 12 in the stacking direction Z. Although not shown in the figure, a gasket that seals the space between the two fuel cell units 12 is provided between the anode separator 24 and the cathode separator 25 that contact each other.

[0034] 1 and 2, the separator 17 has a plurality of cooling grooves 36 that constitute the cooling flow paths 21. The cooling grooves 36 are formed on the surface of the separator 17 opposite to the surface on which the gas flow paths 27 are formed. The cooling grooves 36 are formed by the rear surface shape of the ribs 28. The cooling flow paths 21 are formed by the gaps between the cooling grooves 36 of the anode separator 24 and the cooling grooves 36 of the cathode separator 25. The cooling medium supplied from the coolant supply manifold M5 flows through the cooling flow paths 21 and is discharged from the coolant discharge manifold M6.

[0035] <Operation of the embodiment> When generating electricity using the fuel cell 12, the reactant gas is supplied to the gas flow path 27 through the through-hole hs1 of the separator 17 and then discharged from the through-hole hs2. That is, in the gas flow path 27, the reactant gas flows through the inlet section 30, the mesh section 29, and the outlet section 31 in this order. The reactant gas flows through the mesh section 29 of the gas flow path 27 and is thereby supplied to the power generation section 15. In the power generation section 15, electricity is generated by an electrochemical reaction caused by the reactant gas.

[0036] Here, the mesh section 29 corresponding to the power generation section 15 has a large number of confluence sections 33 where the reactant gases converge. In the gas flow path 27, the pressure loss of the reactant gas downstream of the confluence sections 33 is greater than the pressure loss of the reactant gas upstream of the confluence sections 33. Therefore, in the portion of the gas flow path 27 downstream of the multiple confluence sections 33, the amount of reactant gas flowing into the power generation section 15 is greater than in the portion upstream of the confluence sections 33.

[0037] In addition, the length L in the X-axis direction of the multiple ribs 28 aligned in the X-axis direction becomes shorter stepwise for each rib 28 from the inlet 30 side toward the outlet 31 side. For this reason, when a plurality of fuel cell units 12 are stacked, each configured such that a pair of separators 17 are arranged inverted relative to each other about the imaginary axis V so that one end and the other end in the X-axis direction are swapped, the positions of the gas flow channels 27 and the ribs 28 of the separators 17 that contact each other in two fuel cell units 12 adjacent to each other in the stacking direction Z are misaligned relative to each other in the X-axis direction.

[0038] This prevents the irregularities that form the gas flow paths 27 and ribs 28 of the separators 17 that contact each other in two adjacent fuel cell units 12 in the stacking direction Z from fitting together. This ensures a stable and well-balanced surface pressure on the opposing surfaces 26 of the separators 17 against the power generation unit 15, thereby improving the adhesion of the opposing surfaces 26 of the separators 17 to the power generation unit 15. This allows the reactant gas to be efficiently supplied from the gas flow paths 27 to the power generation unit 15.

[0039] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) In the fuel cell 12, the length L in the X-axis direction of the multiple ribs 28 arranged in the X-axis direction that form the mesh of the mesh portion 29 of the gas flow path 27 gradually decreases for each rib 28 from the inlet portion 30 side toward the outlet portion 31 side.

[0040] According to the above configuration, the reactive gas can be efficiently supplied from the gas flow passage 27 to the power generation section 15 in accordance with the operation of the above embodiment. (2) In the fuel cell 12, the pair of separators 17 have the same configuration.

[0041] According to the above configuration, the pair of separators 17 can be made of a common part, and therefore the number of parts can be reduced compared to when the pair of separators 17 have different configurations.

[0042] (3) In the fuel cell 12, the width H of the rib 28 in the Y-axis direction is 2 mm or less. According to the above configuration, it is possible to prevent a shortage of reactant gas supplied to the portion of the power generation section 15 that comes into contact with the rib 28.

[0043] <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.

[0044] 5, the ribs 28 may be diamond-shaped, and the mesh portion 29 of the gas flow path 27 may be configured such that one diamond-shaped annular flow path 40 surrounding the rib 28 and one linear flow path 41 extending in the X-axis direction are arranged alternately in the X-axis direction. In this case, the length L in the X-axis direction of the multiple ribs 28 arranged in the X-axis direction may be gradually increased or decreased from one side to the other in the X-axis direction.

[0045] 6, the ribs 28 may be triangular, and the mesh portion 29 of the gas flow path 27 may be configured such that one triangular annular flow path 42 surrounding the rib 28 and one linear flow path 41 extending in the X-axis direction are arranged alternately in the X-axis direction. In this case, the length L in the X-axis direction of the multiple ribs 28 arranged in the X-axis direction may be gradually increased or decreased from one side to the other in the X-axis direction.

[0046] 7, the rib 28 may be formed in a hexagonal shape rotated by 90°, and the mesh portion 29 of the gas flow path 27 may be configured such that one hexagonal annular flow path 43 surrounding the rib 28 and a pair of linear flow paths 44 aligned in the Y-axis direction and extending in the X-axis direction are arranged alternately in the X-axis direction. In this case, the length L in the X-axis direction of the multiple ribs 28 aligned in the X-axis direction may be gradually increased or decreased from one side to the other in the X-axis direction.

[0047] 8, the ribs 28 may be hexagonal in shape, rotated 90°, and the mesh portion 29 of the gas flow path 27 may be configured such that triple flow paths 43 connected in the X-axis direction and a pair of linear flow paths 44 aligned in the Y-axis direction and extending in the X-axis direction are alternately arranged in the X-axis direction. In this case, the length L in the X-axis direction of the triple ribs 28 aligned in the X-axis direction may be gradually increased or decreased from one side to the other side in the X-axis direction.

[0048] As shown in FIG. 9, the mesh portion 29 of the gas flow path 27 may be configured such that the branching portion 32 branches from one flow path into three flow paths, and the confluence portion 33 merges the three flow paths into one flow path.

[0049] The mesh portion 29 of the gas flow path 27 may be configured such that the branching portion 32 branches from one flow path into four or more flow paths, and the confluence portion 33 converges the four or more flow paths into one flow path.

[0050] The width H of the rib 28 in the Y-axis direction does not necessarily have to be 2 mm or less. The pair of separators 17 may have different configurations. The gas flow path 27 may be configured so that the width downstream of the branching portion 32 where the reactant gas branches is narrower than the width upstream of the branching portion 32. Typically, in the gas flow path 27, the pressure loss of the reactant gas downstream of the branching portion 32 is smaller than the pressure loss of the reactant gas upstream of the branching portion 32. In this regard, with this configuration, the pressure loss of the reactant gas downstream of the branching portion 32 in the gas flow path 27 can be increased, and therefore the amount of reactant gas flowing from the gas flow path 27 into the power generation unit 15 can be increased.

[0051] The gas flow channel 27 may be configured such that the width downstream of the branching portion 32 where the reaction gas branches is greater than the width upstream of the branching portion 32 . In the fuel cell 12, the length L in the X-axis direction of the multiple ribs 28 arranged in the X-axis direction that form the mesh of the mesh portion 29 of the gas flow path 27 may be configured to increase stepwise for each rib 28 from the inlet portion 30 side toward the outlet portion 31 side.

[0052] In the fuel cell 12, the length L in the X-axis direction of the multiple ribs 28 arranged in the X-axis direction that form the mesh of the mesh portion 29 of the gas flow path 27 may be configured to become longer or shorter in stages for every two or more ribs 28 from the inlet portion 30 side toward the outlet portion 31 side.

[0053] The length L of the rib 28A and the length L of the rib 28B may be the same. The length L of the rib 28B and the length L of the rib 28C may be the same. The length L of the rib 28C and the length L of the rib 28D may be the same.

[0054] The length L of the rib 28D and the length L of the rib 28E may be the same. The shape of the separator 17 is not limited to a rectangular shape, but may be a polygonal shape other than a rectangular shape (for example, a hexagonal shape or an octagonal shape), a circular shape, or an elliptical shape.

[0055] The shape of the ribs 28 is not limited to a hexagonal shape, but may be any polygonal shape other than a hexagonal shape (for example, a square or octagonal shape). [Explanation of symbols]

[0056] 11...Fuel cell stack 12...Fuel cell 13...long side 14...short 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 24...Anode separator 25...Cathode separator 26...Opposite surface 27...Gas flow path 28...Rib 28A~28E...Rib 29...Reticulum 30…Inflow part 31...Outlet 32...Branch 33...Confluence 34...Upstream connecting channel 35...Downstream connecting channel 36…Cooling groove 40~44...Flow path hf1~hf6: Through hole hs1~hs6: Through hole H…width L...length 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 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 separators sandwiching the power generation section, a gas flow channel through which a reactant gas flows and a rib adjacent to the gas flow channel are provided on a surface of the separator facing the power generation section; the gas flow path includes a mesh-like portion formed in a region of the opposing surface corresponding to the power generation portion, an inlet portion connected to one end of the mesh portion in one direction and allowing the reactant gas to flow into the mesh portion, and an outlet portion connected to the other end of the mesh portion opposite to the one end in the one direction and allowing the reactant gas to flow out of the mesh portion, The mesh of the mesh portion is formed by the ribs, A fuel cell characterized in that the length in one direction of the multiple ribs that form the mesh becomes gradually longer or shorter for at least one rib from the inlet side to the outlet side.

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

3. 3. The fuel cell according to claim 1, wherein the width of the rib in the direction perpendicular to the one direction is 2 mm or less.

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