Fuel cell

Abstract

In this fuel cell: (i) the flow path cross-sectional area of a first proximal flow path (111j+1) is larger than the flow path cross-sectional area of one distal flow path (120j+1), and the flow path cross-sectional area of a second proximal flow path (112j+1) is larger than the flow path cross-sectional area of one distal flow path (120j+1); or (ii) a first distal flow path (121j+1) is a flow path adjacent to the first proximal flow path (111j+1), a second distal flow path (121j+1) is a flow path adjacent to the second proximal flow path (112j+1), the flow path cross-sectional area of the first proximal flow path (111j+1) is larger than the flow path cross-sectional area of the first distal flow path (121j+1), and the flow path cross-sectional area of the second proximal flow path (112j+1) is larger than the flow path cross-sectional area of the second distal flow path (121j+1).

Description

fuel cell

[0001] The present disclosure relates to fuel cells.

[0002] To effectively utilize hydrogen, one of the next-generation energy sources, further improvements in fuel cell performance are required. To improve fuel cell performance, it is important to increase the power generated per unit cell. One way to increase the power generated per unit cell is to suppress the short-circuit phenomenon.

[0003] JP 2001-076746 A JP 2008-004478 A

[0004] The present disclosure provides a technique suitable for suppressing the shortcut phenomenon.

[0005] The present disclosure relates to a catalytic converter comprising: an anode separator; a cathode separator; a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane and disposed between the anode separator and the cathode separator; a fuel gas flow channel provided between the anode and the anode separator; and an oxidant gas flow channel provided between the cathode and the cathode separator, wherein at least one of the fuel gas flow channel and the oxidant gas flow channel has, from upstream to downstream in a flow direction of a reactive gas which is a fuel gas or an oxidant gas, a first flow channel group, a second flow channel group, and a third flow channel group, in this order, from upstream to downstream in a flow direction of a reactive gas which is a fuel gas or an oxidant gas, the first flow channel group and the second flow channel group being flow channel groups which allow the reactive gas to flow in opposite directions to each other and which are separated by a first rib; and the second flow channel group and the third flow channel group being flow channel groups which allow the reactive gas to flow in opposite directions to each other and which are separated by a second rib. The second group of flow paths includes a first proximal flow path, a second proximal flow path, and at least one distal flow path, wherein the first proximal flow path is partitioned by the first rib, and the second proximal flow path is partitioned by the second rib, and (i) the one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a flow path cross-sectional area of ​​the first proximal flow path is larger than a flow path cross-sectional area of ​​the one distal flow path, and a flow path cross-sectional area of ​​the second proximal flow path is larger than a flow path cross-sectional area of ​​the one distal flow path, or (ii) the at least one distal flow path includes a first distal flow path and a second distal flow path, and the first distal flow path is a flow path adjacent to the first proximal flow path and the second distal flow path is a flow path adjacent to the second proximal flow path, and a flow path cross-sectional area of ​​the first proximal flow path is larger than a flow path cross-sectional area of ​​the first distal flow path, and a flow path cross-sectional area of ​​the second proximal flow path is larger than a flow path cross-sectional area of ​​the second distal flow path.

[0006] The technology according to the present disclosure is suitable for suppressing the shortcut phenomenon.

[0007] FIG. 13 is a schematic cross-sectional view of a fuel cell stack according to embodiment 1; FIG. 14 is a first plan view of an anode separator; FIG. 15 is a plan view of a cathode separator; FIG. 16 is a second plan view of an anode separator showing another shape of a refrigerant channel; FIG. 17 is a plan view of a reactive gas channel according to a first example of embodiment 1; FIG. 18 is a cross-sectional view of a reactive gas channel according to a second example of embodiment 1; FIG. 19 is a cross-sectional view of a reactive gas channel according to a second example of embodiment 1; FIG. 20 is an explanatory diagram of suppression of a shortcut phenomenon according to embodiment 1; FIG. 21 is an explanatory diagram of an example of a channel shape; FIG. 22 is an explanatory diagram of a specific channel group;

[0008] (Findings that Form the Basis of the Present Disclosure) When the present inventors arrived at the idea of ​​the present disclosure, studies were being conducted to increase the power generation capacity of fuel cells. Suppressing the short-circuit phenomenon is an effective way to increase the power generation capacity.

[0009] However, suppressing the shortcut phenomenon is not necessarily easy. Specifically, a fuel cell has a laminated structure in which a separator, a gas diffusion layer, a catalyst layer, and an electrolyte membrane are laminated in this order. Grooves are provided between the ribs of the separator. The grooves function as flow paths for the reactive gas, guiding the reactive gas to the gas diffusion layer. The mechanism by which the shortcut phenomenon occurs in this configuration will be explained with reference to FIGS. 13 to 16 .

[0010] Fig. 13 is a plan view of the separator 502 of Patent Document 1. Figs. 14 and 15 are cross-sectional views of the separator 502. Fig. 16 is an explanatory diagram of the shortcut phenomenon in Patent Document 1.

[0011] As shown in Fig. 13, a serpentine flow path 530 is formed in the separator 502. The serpentine flow path 530 includes a flow path group 531 and a flow path group 532 arranged parallel to each other. The flow path group 531 and the flow path group 532 are separated by a rib 540. In Fig. 13, the reactive gas flows from left to right through the flow path group 531, turns back, and then flows from right to left through the flow path group 532.

[0012] The flow path group 531 includes a flow path 511. The flow path group 532 includes a flow path 513. The flow paths 511 and 513 are separated by a rib 540. A position 561 in the flow path 511 and a position 562 in the flow path 513 face each other with the rib 540 interposed therebetween.

[0013] 16 , the reactive gas flows along the serpentine flow path 530 from position 561 through position 565 to position 562, bypassing the rib 540. Position 565 is located near the right end of the rib 540 in the drawing. Here, the pressure loss that occurs when the reactive gas travels from position 561 to position 565 is denoted as ΔP1. The pressure loss that occurs when the reactive gas travels from position 565 to position 562 is denoted as ΔP2. The pressure loss that occurs when the reactive gas travels from position 561 to position 562 through position 565 is denoted as ΔP. ​​ΔP = ΔP1 + ΔP2.

[0014] A pressure difference corresponding to the pressure loss ΔP is applied between the position 561 and the position 562. This pressure difference can cause a shortcut phenomenon in which reactive gas flows from the position 561 to the position 562 by passing through a portion of the gas diffusion layer 590 ( FIGS. 14 and 15 ) that faces the rib 540. Under such circumstances, the present inventors came up with the idea of ​​suppressing the shortcut phenomenon by reducing the pressure loss ΔP.

[0015] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters or redundant description of substantially the same configuration may be omitted.

[0016] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0017] First Embodiment Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 12. FIG.

[0018] 1 is a schematic cross-sectional view of a fuel cell stack 200 according to embodiment 1. The fuel cell stack 200 includes a plurality of fuel cells 100 stacked one on top of the other.

[0019] The fuel cell 100 includes a membrane electrode assembly 10, an anode separator 20, and a cathode separator 30. The membrane electrode assembly 10 is disposed between the anode separator 20 and the cathode separator 30. The fuel cell 100 is, for example, a polymer electrolyte fuel cell.

[0020] The membrane electrode assembly 10 can also be used in other electrochemical devices, such as a hydrogen purification device that purifies hydrogen.

[0021] The membrane electrode assembly 10 includes an anode 13, an electrolyte membrane 12, and a cathode 16. The anode 13 is bonded to one surface of the electrolyte membrane 12. The cathode 16 is bonded to the other surface of the electrolyte membrane 12.

[0022] The membrane electrode assembly 10 may include a frame 19. The frame 19 is disposed around the membrane electrode assembly 10 and fixes the membrane electrode assembly 10 between the anode separator 20 and the cathode separator 30. The frame 19 maintains airtightness around the membrane electrode assembly 10. The frame 19 may be a metal member, a resin member, or a member made by combining these.

[0023] The electrolyte membrane 12 is disposed between the anode 13 and the cathode 16. The electrolyte membrane 12 is made of a polymer material having proton conductivity. For example, the electrolyte membrane 12 is a membrane made of a perfluorocarbon sulfonic acid-based polymer material having sulfonic acid groups, or a hydrocarbon-based polymer material.

[0024] The anode 13 includes an anode catalyst layer 14 and an anode gas diffusion layer 15. The anode catalyst layer 14 is disposed between the electrolyte membrane 12 and the anode gas diffusion layer 15. The cathode 16 includes a cathode catalyst layer 17 and a cathode gas diffusion layer 18. The cathode catalyst layer 17 is disposed between the electrolyte membrane 12 and the cathode gas diffusion layer 18.

[0025] The anode catalyst layer 14 has a function of promoting an electrochemical reaction that dissociates hydrogen molecules into protons. The anode catalyst layer 14 includes an electrode catalyst and a polymer electrolyte. The anode catalyst layer 14 may include, as the electrode catalyst, carbon particles carrying catalyst particles and a polymer electrolyte.

[0026] The anode gas diffusion layer 15 has a function of supplying a fuel gas (anode gas) to the anode catalyst layer 14 and a function of receiving electrons from the anode catalyst layer 14. The anode gas diffusion layer 15 is made of a gas-permeable and electrically conductive material. The anode gas diffusion layer 15 has, as its main material, for example, an electrically conductive porous body. An example of the porous body is a carbon fiber aggregate such as carbon paper.

[0027] The cathode catalyst layer 17 has a function of promoting an electrochemical reaction that produces water from protons and oxygen. The cathode catalyst layer 17 includes an electrode catalyst and a polymer electrolyte. The cathode catalyst layer 17 may include, as the electrode catalyst, carbon particles carrying catalyst particles and a polymer electrolyte. The carbon particles may be mesoporous carbon particles. The cathode catalyst layer 17 may further include conductive fibers.

[0028] The cathode gas diffusion layer 18 has a function of supplying an oxidant gas (cathode gas) to the cathode catalyst layer 17 and a function of transferring electrons to the cathode catalyst layer 17. The cathode gas diffusion layer 18 is made of a gas-permeable and electrically conductive material. The cathode gas diffusion layer 18 contains, for example, an electrically conductive porous body as its main material. An example of the porous body is a carbon fiber aggregate such as carbon paper.

[0029] An example of the fuel gas is a hydrogen-containing gas. The hydrogen-containing gas may be a gas produced from hydrocarbons by steam reforming or may be pure hydrogen gas with a hydrogen concentration of 99% or more. An example of the oxidant gas is air.

[0030] A fuel gas flow channel 40 is provided between the anode 13 and the anode separator 20. Fuel gas is supplied to the anode 13 through the fuel gas flow channel 40. In this embodiment, a groove is provided in the anode separator 20 as the fuel gas flow channel 40. However, the fuel gas flow channel 40 may be formed of a member separate from the anode separator 20.

[0031] An oxidant gas flow field 50 is provided between the cathode 16 and the cathode separator 30. An oxidant gas is supplied to the cathode 16 through the oxidant gas flow field 50. In this embodiment, a groove is provided in the cathode separator 30 as the oxidant gas flow field 50. However, the oxidant gas flow field 50 may be formed of a member separate from the cathode separator 30.

[0032] The anode separator 20 and the cathode separator 30 are each made of a conductive material such as carbon or metal, and may be provided with a corrosion-resistant coating such as resin or plating to prevent corrosion.

[0033] The fuel cell 100 further includes a coolant flow channel 60 separated from the oxidant gas flow channel 50 by the cathode separator 30. A coolant such as brine or water is supplied to the coolant flow channel 60. In this embodiment, a groove is provided in the anode separator 20 as the coolant flow channel 60. That is, the fuel gas flow channel 40 is provided on a first surface of the anode separator 20, and the coolant flow channel 60 is provided on a second surface of the anode separator 20. The first and second surfaces of the anode separator 20 refer to the two main surfaces of the plate-like anode separator 20. The surface that contacts the anode 13 is the first surface, and the surface that contacts the cathode separator 30 is the second surface.

[0034] The coolant flow path 60 may be formed by a member separate from the anode separator 20. The coolant flow path 60 may be disposed between the anode separator 20 and the cathode separator 30 of adjacent fuel cells 100.

[0035] The fuel gas flow channel 40 and the oxidant gas flow channel 50 are configured so that the fuel gas and the oxidant gas flow, respectively, from the first side to the second side of the membrane electrode assembly 10. The coolant flow channel 60 is configured so that the coolant flows from the second side to the first side of the membrane electrode assembly 10. That is, the fuel gas flows counter to the coolant, and the oxidant gas flows counter to the coolant. This configuration can strengthen cooling of the downstream regions of the fuel gas flow channel 40 and the oxidant gas flow channel 50 and increase the humidity of the fuel gas and the oxidant gas in the downstream regions. Increasing the humidity of the oxidant gas in the downstream regions increases the moisture content of the cathode gas diffusion layer 18 facing the downstream region of the oxidant gas flow channel 50 and improves the proton conductivity of the cathode catalyst layer 17. As a result, the current density in the downstream region of the oxidant gas flow channel 50 can be increased, and ultimately, the current density distribution in the in-plane direction of the membrane electrode assembly 10 can be made uniform. The fuel gas flow path 40, the oxidant gas flow path 50, and the refrigerant flow path 60 may be configured so that the fuel gas, the oxidant gas, and the refrigerant each flow from the first side to the second side of the membrane electrode assembly 10.

[0036] The fuel gas flow field 40 has an inlet 40a and an outlet 40b. The oxidant gas flow field 50 has an inlet 50a and an outlet 50b. The coolant flow field 60 has an inlet 60a and an outlet 60b. The inlet 40a of the fuel gas flow field 40, the inlet 50a of the oxidant gas flow field 50, and the outlet 60b of the coolant flow field 60 are located on a first side of the membrane electrode assembly 10. The outlet 40b of the fuel gas flow field 40, the outlet 50b of the oxidant gas flow field 50, and the inlet 60a of the coolant flow field 60 are located on a second side of the membrane electrode assembly 10. With this configuration, the coolant flow can be directed opposite the flows of the fuel gas and the oxidant gas. This increases the degree of cooling in the downstream regions of the fuel gas flow field 40 and the oxidant gas flow field 50, and increases the humidity of the fuel gas and the oxidant gas in the downstream regions.

[0037] In this embodiment, the membrane electrode assembly 10 and the fuel cell 100 have a rectangular shape in a plan view. A first side of the membrane electrode assembly 10 and the fuel cell 100 is the side on which one of a pair of sides positioned in a direction perpendicular to the thickness direction of the electrolyte membrane 12 is located. A second side of the fuel cell 100 is the side on which the other of the pair of sides positioned in a direction perpendicular to the thickness direction of the electrolyte membrane 12 is located. In the example of FIG. 1 , the X direction is the thickness direction of the electrolyte membrane 12. The Y direction and the Z direction are each perpendicular to the thickness direction of the electrolyte membrane 12.

[0038] The Z direction is, for example, a direction parallel to the vertical direction. The X direction is, for example, a direction parallel to the horizontal direction. The Y direction is, for example, a direction parallel to the horizontal direction and perpendicular to the thickness direction of the electrolyte membrane 12. The first side of the membrane electrode assembly 10 and the fuel cell 100 may be the upper side in the vertical direction. The second side of the membrane electrode assembly 10 and the fuel cell 100 may be the lower side in the vertical direction. In this case, the fuel gas and the oxidant gas flow from the upper side to the lower side in the vertical direction, and the coolant flows from the lower side to the upper side in the vertical direction.

[0039] In this embodiment, an inlet 40a of the fuel gas flow channel 40 is provided at one end of the fuel cell 100 in the Z direction. An outlet 40b of the fuel gas flow channel 40 is provided at the other end of the fuel cell 100 in the Z direction. The inlet 40a and outlet 40b of the fuel gas flow channel 40 penetrate the anode separator 20 and the cathode separator 30 in the thickness direction. The inlets 40a of adjacent fuel cells 100 are connected to each other. The outlets 40b of adjacent fuel cells 100 are connected to each other. This allows fuel gas to be supplied to the fuel gas flow channel 40 from outside the fuel cell stack 200, and allows unconsumed fuel gas to be discharged from the fuel gas flow channel 40 to outside the fuel cell stack 200.

[0040] In this embodiment, an inlet 50a of the oxidant gas flow channel 50 is provided at one end of the fuel cell 100 in the Z direction. An outlet 50b of the oxidant gas flow channel 50 is provided at the other end of the fuel cell 100 in the Z direction. The inlet 50a and outlet 50b of the oxidant gas flow channel 50 penetrate the anode separator 20 and the cathode separator 30 in the thickness direction. The inlets 50a of adjacent fuel cells 100 are connected to each other. The outlets 50b of adjacent fuel cells 100 are connected to each other. This allows oxidant gas to be supplied to the oxidant gas flow channel 50 from outside the fuel cell stack 200, and allows unconsumed oxidant gas and water vapor to be discharged from the oxidant gas flow channel 50 to outside the fuel cell stack 200.

[0041] In this embodiment, an outlet 60b of the coolant flow path 60 is provided at one end of the fuel cell 100 in the Z direction. An inlet 60a of the coolant flow path 60 is provided at the other end of the fuel cell 100 in the Z direction. The inlet 60a and outlet 60b of the coolant flow path 60 penetrate the anode separator 20 and the cathode separator 30 in the thickness direction. The inlets 60a of adjacent fuel cells 100 are connected to each other. The outlets 60b of adjacent fuel cells 100 are connected to each other. This allows a coolant to be supplied to the coolant flow path 60 from outside the fuel cell stack 200, and allows the coolant to be discharged from the coolant flow path 60 to outside the fuel cell stack 200.

[0042] FIG. 2 is a first plan view of the anode separator 20. The first plan view is a plan view of the surface 20p that contacts the anode 13. In this embodiment, the fuel gas flow channel 40 is a serpentine flow channel including a plurality of flow channel groups 41 and a plurality of flow channel groups 42. In the example of FIG. 2, the flow channel group 41 is a portion extending in a direction from the first side (upper side in the figure) to the second side (lower side in the figure) of the membrane electrode assembly 10. The flow channel group 41 may have an arc shape in a plan view. The flow channel group 42 is a portion extending in a direction perpendicular to the direction from the first side to the second side of the membrane electrode assembly 10. With this configuration, fuel gas can be supplied to every corner of the anode 13.

[0043] FIG. 3 is a plan view of the cathode separator 30. In this embodiment, the oxidant gas flow field 50 is a serpentine flow field including a plurality of flow field groups 51 and a plurality of flow field groups 52. In the example of FIG. 3, the flow field group 51 is a portion extending in a direction from the first side (upper side in the figure) of the membrane electrode assembly 10 toward the second side (lower side in the figure). The flow field group 51 may have an arc shape in a plan view. The flow field group 52 is a portion extending in a direction perpendicular to the direction from the first side to the second side of the membrane electrode assembly 10. With this configuration, the oxidant gas can be supplied to every corner of the cathode 16.

[0044] 2 and 3 , the flow direction of the fuel gas in the fuel gas flow field 40 is parallel to the flow direction of the oxidant gas in the oxidant gas flow field 50. This configuration makes it easier to efficiently advance the electrochemical reaction in the membrane electrode assembly 10.

[0045] As shown in Figures 2 and 3, when the fuel cell 100 is viewed from a direction parallel to the thickness direction of the electrolyte membrane 12, the flow direction of the fuel gas in the flow path group 42 of the fuel gas flow path 40 is opposite to the flow direction of the oxidizer gas in the flow path group 52 of the oxidizer gas flow path 50.

[0046] The fuel cell stack 200 is installed such that the Z direction is parallel to the vertical direction, for example. In this case, the flow channel groups 42 of the fuel gas flow channel 40 and the flow channel groups 52 of the oxidant gas flow channel 50 are parallel to the horizontal direction.

[0047] FIG. 4 is a second plan view of the anode separator 20. The second plan view is a plan view of the surface 20q opposite to the surface 20p in contact with the anode 13. In this embodiment, the refrigerant flow path 60 is a serpentine flow path including a plurality of flow path groups 61 and a plurality of flow path groups 62. In the example of FIG. 4, the flow path group 61 is a portion extending in a direction from the second side (lower side in the figure) of the membrane electrode assembly 10 toward the first side (upper side in the figure). The flow path group 61 may have an arc shape in a plan view. The flow path group 62 is a portion extending in a direction perpendicular to the direction from the second side to the first side of the membrane electrode assembly 10. This configuration enables uniform cooling of the membrane electrode assembly 10 and improves the efficiency of exhaust heat recovery.

[0048] Figure 5 is a second plan view of the anode separator 20, showing another shape of the refrigerant flow path 60. In the example shown in Figure 5, the refrigerant flow path 60 is not serpentine, but has multiple portions extending in a direction from the second side (the lower side in the figure) of the membrane electrode assembly 10 to the first side (the upper side in the figure). With this configuration, the pressure loss in the refrigerant flow path 60 can be reduced, allowing the refrigerant to flow smoothly through the refrigerant flow path 60.

[0049] The configuration of the fuel cell 100 of the first embodiment will be further described below with reference to FIGS.

[0050] In the first embodiment, "orthogonal" does not necessarily mean that the angle formed is strictly 90°. In the first embodiment, an angle formed is considered to be "orthogonal" when it is between 85° and 95°.

[0051] In the first embodiment, "parallel" does not necessarily mean that the angle formed is strictly 0°. In the first embodiment, when the angle formed is between 0° and 5°, it is treated as "parallel."

[0052] FIG. 6 is a plan view of a reactive gas flow path FG according to a first example of the first embodiment. FIG. 7 is a cross-sectional view of a reactive gas flow path FG according to the first example of the first embodiment. FIG. 8 is a plan view of a reactive gas flow path FG according to a second example of the first embodiment. FIG. 9 is a cross-sectional view of a reactive gas flow path FG according to the second example of the first embodiment. The cross-sectional views of FIGS. 7 and 9 show the proximal flow path 111. j+1 and proximal flow channel 112 j+1 The cross section is perpendicular to the direction in which the wire extends.

[0053] At least one of the fuel gas flow field 40 and the oxidizing gas flow field 50 in the first and second examples of FIGS. 6 to 9 can correspond to the reactive gas flow field FG.

[0054] 6 to 9, the reactive gas flow passage FG is divided by separators SP. The reactive gas flow passage FG includes a plurality of flow passage groups 130 and a plurality of flow passage groups 170.

[0055] The multiple flow path groups 130 are aligned in a direction parallel to one another. In the first and second examples of Figures 6 to 9, the alignment direction is the Z direction. Each flow path group 130 includes multiple flow paths 135. A plurality of ribs 140 and a plurality of ribs 150 are provided on the separator SP so as to face the gas diffusion layer GDL. The multiple flow paths 135 are partitioned by the multiple ribs 140 and the multiple ribs 150.

[0056] Each flow path group 170 connects the adjacent flow path group 130 to the flow path group 130. In the reactive gas flow path FG, each flow path group 170 serves to turn back the flow direction. Each flow path group 170 includes a plurality of flow paths 175. The plurality of flow paths 175 are partitioned by a plurality of ribs 140 and a plurality of ribs 150. Specifically, the plurality of ribs 150 are turned back, and the plurality of flow paths 175 are provided along these turning portions.

[0057] In the reactive gas flow passages FG corresponding to the fuel gas flow passages 40, the plurality of flow passage groups 130 may correspond to the plurality of flow passage groups 42. The plurality of flow passage groups 170 may correspond to the plurality of flow passage groups 41. The separator SP may correspond to the anode separator 20. The gas diffusion layer GDL may correspond to the anode gas diffusion layer 15.

[0058] In the reactive gas flow passages FG corresponding to the oxidizing gas flow passages 50, the plurality of flow passage groups 130 may correspond to the plurality of flow passage groups 52. The plurality of flow passage groups 170 may correspond to the plurality of flow passage groups 51. The separator SP may correspond to the cathode separator 30. The gas diffusion layer GDL may correspond to the cathode gas diffusion layer 18.

[0059] Specifically, the reactive gas flow path FG is a serpentine flow path. The serpentine flow path includes a plurality of flow path groups 130 and a plurality of flow path groups 170. The serpentine flow path may also be referred to as a serpentine flow path.

[0060] Hereinafter, a natural number N is used. N is the number of flow passage groups 130 in the reactive gas flow passage FG. In the first embodiment, N is 3 or more.

[0061] The N in the reactive gas flow passage FG corresponding to the fuel gas flow passage 40 and the N in the reactive gas flow passage FG corresponding to the oxidant gas flow passage 50 may be the same or different. In the reactive gas flow passage FG corresponding to the fuel gas flow passage 40, "N" may be replaced with "T" and "j" may be replaced with "h". In the reactive gas flow passage FG corresponding to the oxidant gas flow passage 50, "N" may be replaced with "U" and "j" may be replaced with "i".

[0062] In the following, each of the plurality of flow path groups 130 will be referred to as flow path group 130 1 , flow path group 130 2 , . . . , flow path group 130 N Each of the plurality of ribs 140 is referred to as rib 140 1 , rib 140 2 , . . . , rib 140 N-1 It is called.

[0063] Flow path group 1301, flow path group 1302, ..., flow path group 130 N are arranged in this order from the upstream side to the downstream side in the flow direction of the reactive gas.

[0064] For all natural numbers j that satisfy 1≦j≦N, the flow path group 130 j The flow path 135 is j adjacent flow paths 135 j and flow path 135 j These flow paths 135 are located between j The rib 150 that divides the j It is called.

[0065] For all natural numbers j that satisfy 1≦j≦N−1, the flow path group 130 j and flow path group 130 j+1 flow the reactive gases in opposite directions; j and flow path group 130 j+1 , rib 140 j It is separated by.

[0066] 6 and 8, the flow path group 130 j The flow channels 130 allow reactive gas to flow from left to right. j+1 The flow passages 130 allow reactive gas to flow from right to left. j+2 The reactive gas flows from left to right.

[0067] In the fuel gas flow field 40 corresponding to the reactive gas flow field FG, the reactive gas is a fuel gas. In the oxidizing gas flow field 50 corresponding to the reactive gas flow field FG, the reactive gas is an oxidizing gas.

[0068] For all natural numbers j that satisfy 1≦j≦N, the flow path group 130 j In the flow path 135 j and Rib 150 j are arranged alternately.

[0069] The plurality of channels 135 1 in the channel group 130 1 includes a proximal channel 112 1 , and the proximal channel 112 1 is defined by ribs 140 1 .

[0070] For all natural numbers j that satisfy 1≦j≦N−2, the flow path group 130 j+1 A plurality of flow paths 135 in j+1 is the proximal flow channel 111 j+1 and proximal flow channel 112 j+1 a proximal flow channel 111; j+1 , rib 140 j a proximal flow channel 112; j+1 , rib 140 j+1 It is divided by.

[0071] Flow path group 130 N A plurality of flow paths 135 in N is the proximal flow channel 111 N a proximal flow channel 111; N , rib 140 N-1 It is divided by.

[0072] For all natural numbers j that satisfy 1≦j≦N, in the first example of FIGS. 6 and 7, the flow path group 130 j A plurality of flow paths 135 in j a distal flow channel 120 included in j In the second example of FIGS. 8 and 9, the number of the flow path group 130 is one. j A plurality of flow paths 135 in j a distal flow channel 120 included in j The number of is two.

[0073] In the first example of Figures 6 and 7, the one distal channel 1201 is the channel next to the proximal channel 1121.

[0074] In the first example of FIGS. 6 and 7, for all natural numbers j satisfying 1≦j≦N−2, j+1 is the proximal flow channel 111 j+1 adjacent and proximal flow path 112 j+1 It is the flow path next to the river.

[0075] In the first example of Figures 6 and 7, the one distal flow channel 120 N is the proximal flow channel 111 N It is the flow path next to the river.

[0076] In the second example of Figures 8 and 9, the plurality of distal flow channels 1201 includes a distal flow channel 1221; and the distal flow channel 1221 is a flow channel adjacent to the proximal flow channel 1121.

[0077] In the second example of FIGS. 8 and 9, for all natural numbers j such that 1≦j≦N−2, j+1 is the distal flow channel 121 j+1 and distal flow channel 122 j+1 a distal flow channel 121; j+1 is the proximal flow channel 111 j+1 the distal flow channel 122; j+1 is the proximal flow channel 112 j+1 It is the flow path next to the river.

[0078] In the second example of Figures 8 and 9, N is the distal flow channel 121 N a distal flow channel 121; N is the proximal flow channel 111 N It is the flow path next to the river.

[0079] In the first example of FIGS. 6 and 7, for all natural numbers j satisfying 1≦j≦N−2, j Flow path cross-sectional area S12 j is the one distal flow path 120 j Flow path cross-sectional area S20 j greater than the proximal flow channel 111 j+1 Flow path cross-sectional area S11 j+1 is the one distal flow path 120j+1 Flow path cross-sectional area S20 j+1 greater than the proximal flow channel 112 j+1 Flow path cross-sectional area S12 j+1 is the one distal flow path 120 j+1 Flow path cross-sectional area S20 j+1 greater than the proximal flow channel 111 j+2 Flow path cross-sectional area S11 j+2 is the one distal flow path 120 j+2 Flow path cross-sectional area S20 j+2 is greater than.

[0080] In the second example of FIGS. 8 and 9, for all natural numbers j satisfying 1≦j≦N−2, j Flow path cross-sectional area S12 j is the distal flow channel 122 j Flow path cross-sectional area S22 j greater than the proximal flow channel 111 j+1 Flow path cross-sectional area S11 j+1 is the distal flow channel 121 j+1 Flow path cross-sectional area S21 j+1 greater than the proximal flow channel 112 j+1 Flow path cross-sectional area S12 j+1 is the distal flow channel 122 j+1 Flow path cross-sectional area S22 j+1 greater than the proximal flow channel 111 j+2 Flow path cross-sectional area S11 j+2 is the distal flow channel 121 j+2 Flow path cross-sectional area S21 j+2 is greater than.

[0081] As described above, in the first and second examples of FIGS. 6 to 9, the flow path cross-sectional area S12 j , S11 j+1 , S12 j+1 and S11 j+2 According to this configuration, the flow path cross-sectional area S12 j , S11 j+1 , S12 j+1 and S11 j+2 This makes it easier to increase the value of the short-circuit phenomenon. This point will be described below with reference to FIG.

[0082] FIG. 10 shows the rib 140 j6, 8 and 10 are explanatory diagrams illustrating the suppression of the shortcut phenomenon regarding the flow path group 130. j The proximal flow path 112 j Position 162 in j and the flow path group 130 j+1 The proximal flow path 111 j+1 Position 161 in j+1 However, rib 140 j They are opposed via.

[0083] 6, 8 and 10, the reactive gas flows along the reactive gas flow path FG at location 162 j From position 165 j via position 161 j+1 Rib 140 j The flow bypasses the position 165. j 6 and 8. j It is a position near the right end of

[0084] Here, the reactive gas is introduced into the j From position 165 j The pressure loss that occurs until the pressure reaches j The reactive gas is introduced at position 165 j From position 161 j+1 The pressure loss that occurs until the pressure reaches j The reactive gas is introduced into the reaction chamber at position 162. j From position 165 j via position 161 j+1 The pressure loss that occurs until the pressure reaches j It is expressed as ΔP j =ΔP1 j +ΔP2 j is.

[0085] In FIG. 10, position 162 j and position 161 j+1 Between j However, as described above, according to the first and second examples of FIGS. 6 to 9, the flow path cross-sectional area S12 j Therefore, the pressure loss ΔP1 j In addition, the flow path cross-sectional area S11 j+1Therefore, the pressure loss ΔP2 j Therefore, the pressure loss ΔP j Therefore, the position 162 j From the above, the rib 140 in the gas diffusion layer GDL j and passes through the part opposite to position 161 j+1 This can suppress the short-cut phenomenon in which reactive gas flows to the

[0086] As described above, according to the first and second examples of FIGS. 6 to 9, the flow path cross-sectional area S12 j+1 and S11 j+2 For the same reason, it is easy to increase the position 162 j+1 From the above, the rib 140 in the gas diffusion layer GDL j+1 and passes through the part opposite to position 161 j+2 This can suppress the short-cut phenomenon in which reactive gas flows to the

[0087] By suppressing the shortcut phenomenon, (1) it becomes easier to distribute the reactive gas uniformly in the portion of the gas diffusion layer GDL facing the plurality of ribs 140, and (2) it becomes easier to flow the reactive gas along the reactive gas flow path FG.

[0088] The above (1) is advantageous from the viewpoint of uniforming the current density distribution in the plane direction of the membrane electrode assembly. The above (2) is advantageous from the viewpoint of effectively utilizing the reactive gas over a wide area in the plane direction of the membrane electrode assembly. Therefore, the above (1) and (2) make it possible to increase the power generation of the fuel cell.

[0089] Regarding the above (1), the supply of reactive gas to the portion of the gas diffusion layer GDL facing the rib 140 can be achieved by the following: shortcut phenomenon, and concentration diffusion phenomenon. According to the study by the present inventors, of the shortcut phenomenon and the concentration diffusion phenomenon, increasing the proportion of reactive gas supplied by the concentration diffusion phenomenon can contribute to uniforming the current density distribution in the surface direction of the membrane electrode assembly.

[0090] The above (1) will be described in detail below with reference to Figs. 14 and 15 relating to Patent Document 1. Fig. 14 is a cross-sectional view taken along line A-A' in Fig. 13. Fig. 15 is a cross-sectional view taken along line B-B' in Fig. 13. The cross-sectional views in Figs. 14 and 15 show cross sections perpendicular to the direction in which flow channels 511 and 513 extend.

[0091] The position of flow path 511 shown in Fig. 14 is located upstream of the position of flow path 511 shown in Fig. 15. The position of flow path 513 shown in Fig. 14 is located downstream of the position of flow path 513 shown in Fig. 15. Therefore, the pressure difference between flow paths 511 and 513 is greater in the region shown in Fig. 14 than in the region shown in Fig. 15. This can be understood from the above explanation using Fig. 16 and ΔP = ΔP1 + ΔP2.

[0092] A difference in pressure difference means that there is a difference in the degree of the shortcut phenomenon. At the position (line A-A') in Figure 14, the pressure difference is large, so a large amount of reactive gas is supplied to the portion of the gas diffusion layer 590 facing the rib 540 due to the shortcut phenomenon. In contrast, at the position (line B-B') in Figure 15, the pressure difference is small, so little reactive gas is supplied to the portion of the gas diffusion layer 590 facing the rib 540 due to the shortcut phenomenon. Therefore, a difference occurs in the concentration of reactive gas in the portion of the gas diffusion layer 590 facing the rib 540 between the position in Figure 14 and the position in Figure 15.

[0093] The difference in reactive gas concentration is schematically shown by the difference in level between region 581 of graph 571 in Fig. 14 and region 582 of graph 572 in Fig. 15. Such a difference between the reactive gas concentration in gas diffusion layer 590 at a certain position in the length direction of rib 540 and the reactive gas concentration in gas diffusion layer 590 at another position in the length direction of rib 540 is disadvantageous from the perspective of uniforming the current density distribution.

[0094] In contrast, according to the first and second examples of Figures 6 to 9, the shortcut phenomenon related to the rib 140 is totally suppressed. Therefore, it is difficult for the shortcut phenomenon to cause a difference between the reactive gas concentration of the gas diffusion layer GDL at a certain position in the length direction of the rib 140 and the reactive gas concentration of the gas diffusion layer GDL at another position in the length direction of the rib 140. Therefore, the first and second examples of Figures 6 to 9 are advantageous from the viewpoint of uniforming the current density distribution.

[0095] 13 relating to Patent Document 1, the flow path group 531 includes a flow path 512. The flow paths 511 and 512 are separated by a rib 550. The difference between the reactive gas concentration in region 585 of graph 571 in Fig. 14 and the reactive gas concentration in region 586 of graph 572 in Fig. 15 is small. This is because the pressure difference between the flow paths 511 and 512, which belong to the same flow path group 531 and allow reactive gas to flow in the same direction, is small overall.

[0096] On the other hand, there is a large difference between the reactive gas concentration in region 581 of graph 571 in Fig. 14 and the reactive gas concentration in region 582 of graph 572 in Fig. 15. This is because the pressure difference between flow paths 511 and 513, which belong to adjacent flow path groups 531 and 532 and through which reactive gas flows in opposite directions, is large at one position in the length direction of rib 540 and small at another position.

[0097] In this regard, according to the first and second examples of FIGS. 6 to 9, adjacent flow path groups 130 j , 130 j+1 a proximal flow channel 112 that flows reactive gas in the opposite direction; j and the proximal flow channel 111 j+1 In addition, the pressure difference between the adjacent flow path groups 130 can be suppressed. j+1 , 130 j+2 a proximal flow channel 112 that flows reactive gas in the opposite direction; j+1 and the proximal flow channel 111 j+2 This is advantageous from the viewpoint of making the distribution of the reactive gas uniform and the current density distribution uniform.

[0098] As described above, in the first and second examples of FIGS. 6 to 9, the flow path cross-sectional area S20j , S20 j+1 , S20 j+2 , S22 j , S21 j+1 , S22 j+1 and S21 j+2 According to this configuration, the flow path cross-sectional area S20 j , S20 j+1 , S20 j+2 , S22 j , S21 j+1 , S22 j+1 and S21 j+2 A small cross-sectional area of ​​the flow path is advantageous from the viewpoint of increasing the flow rate of the reactive gas and driving off excess water, thereby suppressing the decrease in power generation caused by excess water.

[0099] In the first example of FIGS. 6 and 7, for all natural numbers j that satisfy 1≦j≦N−2, j Flow path cross-sectional area S12 j In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the flow path cross-sectional area S20 j+1 Flow path cross-sectional area S11 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the flow path cross-sectional area S20 j+1 Flow path cross-sectional area S12 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the flow path cross-sectional area S20 j+2 Flow path cross-sectional area S11 j+2 In one example, the ratio is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0100] In the second example of FIGS. 8 and 9, for all natural numbers j that satisfy 1≦j≦N−2, j Flow path cross-sectional area S12 j In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and j+1 Flow path cross-sectional area S11 j+1In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the flow path cross-sectional area S22 j+1 Flow path cross-sectional area S12 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and j+2 Flow path cross-sectional area S11 j+2 In one example, the ratio is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0101] In the first example of FIGS. 6 and 7, for all natural numbers j satisfying 1≦j≦N−2, j Width W12 j is the one distal flow path 120 j Width W20 j greater than the proximal flow channel 111 j+1 Width W11 j+1 is the one distal flow path 120 j+1 Width W20 j+1 greater than the proximal flow channel 112 j+1 Width W12 j+1 is the one distal flow path 120 j+1 Width W20 j+1 greater than the proximal flow channel 111 j+2 Width W11 j+2 is the one distal flow path 120 j+2 Width W20 j+2 is greater than.

[0102] In the second example of FIGS. 8 and 9, for all natural numbers j satisfying 1≦j≦N−2, j Width W12 j is the distal flow channel 122 j Width W22 j greater than the proximal flow channel 111 j+1 Width W11 j+1 is the distal flow channel 121 j+1 Width W21 j+1 greater than the proximal flow channel 112 j+1 Width W12 j+1 is the distal flow channel 122 j+1 Width W22 j+1greater than the proximal flow channel 111 j+2 Width W11 j+2 is the distal flow channel 121 j+2 Width W21 j+2 is greater than.

[0103] In the first and second examples of FIGS. 6 to 9, the width W12 j , W11 j+1 and W12 j+1 and W11 j+2 According to this configuration, the width W12 j , W11 j+1 and W12 j+1 and W11 j+2 This makes it easy to increase the flow path cross-sectional area S12 j , S11 j+1 and S12 j+1 and S11 j+2 This is advantageous in terms of increasing the proximal flow channel 112. j , 111 j+1 , 112 j+1 and 111 j+2 The area facing the gas diffusion layer GDL is increased, and the proximal flow channel 112 j , 111 j+1 , 112 j+1 and 111 j+2 This is advantageous from the viewpoint of ensuring the supply of reactive gas from the gas diffusion layer GDL to the gas diffusion layer GDL.

[0104] In the first example of FIGS. 6 and 7, for all natural numbers j that satisfy 1≦j≦N−2, j Width W12 j In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and width W20 j+1 Width W11 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and width W20 j+1 Width W12 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and width W20 j+2 Width W11 j+2In one example, the ratio is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0105] In the second example of FIGS. 8 and 9, for all natural numbers j that satisfy 1≦j≦N−2, j Width W12 j In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and width W21 j+1 Width W11 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and width W22 j+1 Width W12 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and width W21 j+2 Width W11 j+2 In one example, the ratio is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0106] In the first example of FIGS. 6 and 7, for all natural numbers j satisfying 1≦j≦N−2, j Depth D12 j is the one distal flow path 120 j Depth D20 j greater than the proximal flow channel 111 j+1 Depth D11 j+1 is the one distal flow path 120 j+1 Depth D20 j+1 greater than the proximal flow channel 112 j+1 Depth D12 j+1 is the one distal flow path 120 j+1 Depth D20 j+1 greater than the proximal flow channel 111 j+2 Depth D11 j+2 is the one distal flow path 120 j+2 Depth D20 j+2 is greater than.

[0107] In the second example of FIGS. 8 and 9, for all natural numbers j satisfying 1≦j≦N−2, j Depth D12j is the distal flow channel 122 j Depth D22 j greater than the proximal flow channel 111 j+1 Depth D11 j+1 is the distal flow channel 121 j+1 Depth D21 j+1 greater than the proximal flow channel 112 j+1 Depth D12 j+1 is the distal flow channel 122 j+1 Depth D22 j+1 greater than the proximal flow channel 111 j+2 Depth D11 j+2 is the distal flow channel 121 j+2 Depth D21 j+2 is greater than.

[0108] In the first and second examples of FIGS. 6 to 9, the depth D12 j , D11 j+1 and D12 j+1 and D11 j+2 According to this configuration, the depth D12 j , D11 j+1 and D12 j+1 and D11 j+2 This makes it easy to increase the flow path cross-sectional area S12 j , S11 j+1 and S12 j+1 and S11 j+2 This is advantageous from the viewpoint of increasing

[0109] In the first example of FIGS. 6 and 7, for all natural numbers j that satisfy 1≦j≦N−2, j Depth D12 j In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the depth D20 j+1 Depth D11 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the depth D20 j+1 Depth D12 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the depth D20 j+2Depth D11 j+2 In one example, the ratio is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0110] In the second example of FIGS. 8 and 9, for all natural numbers j that satisfy 1≦j≦N−2, j Depth D12 j In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and depth D21 j+1 Depth D11 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and the depth D22 j+1 Depth D12 j+1 In one example, the ratio is greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4; and depth D21 j+2 Depth D11 j+2 In one example, the ratio is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0111] In the first example of FIGS. 6 and 7, for all natural numbers j satisfying 1≦j≦N−2, j and the one distal flow path 120 j Rib 150 located between j Width Wb50 j Rib 140 for j Width W40 j In one example, the ratio is greater than 0.7 and less than 1.3, and in one example, greater than 0.8 and less than 1.2; j+1 and the one distal flow path 120 j+1 Rib 150 located between j+1 Width Wa50 j+1 Rib 140 for j Width W40 j In one example, the ratio is greater than 0.7 and less than 1.3, and in one example, greater than 0.8 and less than 1.2; j+1 and the one distal flow path 120 j+1 Rib 150 located betweenj+1 Width Wb50 j+1 Rib 140 for j+1 Width W40 j+1 In one example, the ratio is greater than 0.7 and less than 1.3, and in one example, greater than 0.8 and less than 1.2; j+2 and the one distal flow path 120 j+2 Rib 150 located between j+2 Width Wa50 j+2 Rib 140 for j+1 Width W40 j+1 In one example, the ratio is greater than 0.7 and less than 1.3, and in one specific example, greater than 0.8 and less than 1.2.

[0112] In the second example of FIGS. 8 and 9, for all natural numbers j satisfying 1≦j≦N−2, j and distal flow channel 122 j Rib 150 located between j Width Wd50 j Rib 140 for j Width W40 j In one example, the ratio is greater than 0.7 and less than 1.3, and in one example, greater than 0.8 and less than 1.2; j+1 and distal flow channel 121 j+1 Rib 150 located between j+1 Width Wc50 j+1 Rib 140 for j Width W40 j In one example, the ratio is greater than 0.7 and less than 1.3, and in one example, greater than 0.8 and less than 1.2; j+1 and distal flow channel 122 j+1 Rib 150 located between j+1 Width Wd50 j+1 Rib 140 for j+1 Width W40 j+1 is in one example greater than 0.7 and less than 1.3, and in one specific example greater than 0.8 and less than 1.2; j+2 and distal flow channel 121 j+2 Rib 150 located between j+2 Width Wc50 j+2Rib 140 for j+1 Width W40 j+1 In one example, the ratio is greater than 0.7 and less than 1.3, and in one specific example, greater than 0.8 and less than 1.2.

[0113] Setting the width of the rib 140 and the width of the rib 150 to similar values ​​is advantageous from the viewpoint of making uniform the concentration of the reactive gas in the portion of the gas diffusion layer GDL facing the rib 140 and the concentration of the reactive gas in the portion of the gas diffusion layer GDL facing the rib 150. This point will be explained below with reference to FIG.

[0114] In Patent Document 1, the width of the rib 540 is 1.7 mm, which is 1.7 times the width of the rib 550. In Patent Document 1, the width of the rib 540 is increased to provide a short-cut prevention structure.

[0115] However, in Patent Document 1, because the width of rib 540 is large, the difference in the concentration of the reactive gas in the portion of gas diffusion layer 590 facing rib 540 and the concentration of the reactive gas around that portion of gas diffusion layer 590 tends to be large, as shown by dashed arrow 588 in Figure 15. This is because the concentration diffusion phenomenon is inhibited in region 582 due to the large width of rib 540, and the short-cut phenomenon does not become apparent due to the small pressure difference between flow path 511 and flow path 512. This point will be further explained below with reference to regions 581 and 585 of graph 571 in Figure 14 and regions 582 and 586 of graph 572 in Figure 15.

[0116] The pressure difference between the flow channels 511 and 512, which belong to the same flow channel group 531 and allow reactive gas to flow in the same direction, is generally small. On the other hand, the pressure difference between the flow channels 511 and 513, which belong to adjacent flow channel groups 531 and 532 and allow reactive gas to flow in opposite directions, is large at some positions along the length of the rib 540 and small at other positions.

[0117] In the regions 585 and 586, the pressure difference is small, so the shortcut phenomenon does not become apparent. On the other hand, in the regions 585 and 586, the width of the rib 550 is small, so the reactive gas concentration in the gas diffusion layer 590 is obtained by the concentration diffusion phenomenon.

[0118] In the region 581, the width of the rib 540 is large, which inhibits the concentration diffusion phenomenon. However, in the region 581, the pressure difference is large, so the reactive gas concentration in the gas diffusion layer 590 is obtained by the shortcut phenomenon.

[0119] In region 582, the width of rib 540 is large, which inhibits the concentration diffusion phenomenon. Moreover, in region 582, the pressure difference is small, so the short-cut phenomenon does not become apparent. Therefore, in region 582, the reactive gas concentration in gas diffusion layer 590 is small.

[0120] In contrast, in the first embodiment, the width of the rib 140 and the width of the rib 150 are relatively close to each other. Therefore, the width of the rib 140 is unlikely to become excessively large. This makes it easy to avoid a situation in which the width of the rib 140 excessively inhibits the concentration diffusion phenomenon. This makes it easy to suppress the difference in the reactive gas concentration between the portion of the gas diffusion layer GDL facing the rib 140 and the reactive gas concentration around that portion of the gas diffusion layer GDL. This is advantageous from the viewpoint of uniforming the distribution of the reactive gas and the current density distribution.

[0121] In the first and second examples of FIGS. 6 to 9, for all natural numbers j that satisfy 1≦j≦N−1, j Width W40 j In one example, it is greater than 0.5 mm and less than 1.7 mm, and in one specific example, it is greater than or equal to 0.7 mm and less than or equal to 1.5 mm.

[0122] The cross section of the flow channel 135 perpendicular to the direction in which the flow channel 135 extends may be rectangular or trapezoidal. Here, the concept of rectangle includes a square. FIG. 11 is an explanatory diagram of an example of the shape of the flow channel 135. In the example of FIG. 11, the width W of the opening 135o of the flow channel 135 is o is the width W of the bottom 135b of the flow channel 135 b is greater than.

[0123] In the first and second examples of FIGS. 6 to 9, for all natural numbers j satisfying 1≦j≦N−2, j+1 The width of the opening of the proximal flow channel 111 j+1the width of the bottom of the proximal channel 111; j+1 is the proximal flow channel 111 j+1 The proximal flow channel 112 may have a trapezoidal cross section perpendicular to the direction of extension of the proximal flow channel 112; j+1 The width of the opening of the proximal channel 112 j+1 the width of the bottom of the proximal channel 112; j+1 is the proximal flow channel 112 j+1 In this configuration, the proximal flow channel 111 may have a trapezoidal cross section perpendicular to the direction in which the proximal flow channel 111 extends. j+1 and the proximal flow channel 112 j+1 Therefore, it is easy to supply reactive gas to the gas diffusion layer GDL.

[0124] The width W of the opening 135o of the flow path 135 o and the width W of the bottom 135b of the flow path 135 b When the width of the opening 135o is different from the width of the flow path 135, the width W o and the width W of the bottom 135b b The arithmetic mean of

[0125] 6 to 9, one or more of the reactive gas flow passages FG among the plurality of flow passage groups 170 may correspond to the specific flow passage group 180. FIG. 12 is an explanatory diagram of the specific flow passage group 180.

[0126] The specific flow channel group 180 connects two adjacent flow channel groups 130 among the plurality of flow channel groups 130. The specific flow channel group 180 includes a first throttle flow channel 181 and / or a second throttle flow channel 182. For all natural numbers j that satisfy 1≦j≦N−2, the first throttle flow channel 181 is connected to the proximal flow channel 111. j+1 The first throttle flow channel 181 includes a first throttle 191, and the second throttle flow channel 182 is connected to the proximal flow channel 112. j+1 The second throttle flow path 182 includes a second throttle 192. In this context, the term "throttle" refers to a portion where the cross-sectional area of ​​the flow path is reduced compared to its surroundings. With this configuration, the cross-sectional area S12 j , S11 j+1 , S12 j+1 and the proximal flow channel 111 j+2Even in a situation where the resistance of the flow passage is relatively large, the variation in the resistance of the flow passage can be easily suppressed.

[0127] 6 to 9, the most upstream flow path group among the plurality of flow path groups 130 is flow path group 130. Among the plurality of flow path groups 130, the flow path group adjacent to flow path group 130 is flow path group 130. In the illustrated example, the arrangement direction of the plurality of flow path groups 130 is the Z direction.

[0128] 6 and 8, the flow passage group 130 and the flow passage group 130 are separated by a rib 140. The plurality of flow passages 135 in the flow passage group 130 are separated by a rib 140. E1 , flow path 135 E2 , and one or more flow channels 135 M1 Flow path 135 E1 is a flow channel at one end in the Z direction in the flow channel group 130. E2 is the flow channel at the other end in the Z direction in the flow channel group 130. E2 are separated by ribs 140. One or more channels 135 M1 is the flow path 135 in the Z direction. E1 and flow path 135 E2 Located between.

[0129] Flow path 135 E1 and flow path 135 E2 may also be referred to as an end channel. M1 may also be referred to as an intermediate flow path. E2 is the proximal flow channel 112. M1 is the distal channel 120. In the example of FIG. M1 In the example of FIG. 8, the number of flow paths 135 is one. M1 The number of is two.

[0130] Flow path 135 E2 The cross-sectional area of ​​the flow path is E1 The cross-sectional area of ​​the flow path 135 may be larger than that of the flow path 135. E1 Flow path 135 for the flow path cross-sectional area E2 The ratio of the cross-sectional areas of the flow passages is, in one example, greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4.

[0131] Flow path 135 E1 One or more flow paths 135 for a flow path cross-sectional area of M1 The ratio of the cross-sectional areas of the flow paths is, for example, 0.8 or more and 1.2 or less, and in one specific example, 0.9 or more and 1.1 or less.

[0132] Flow path 135 E2 The width of the flow path 135 E1 The width of the flow channel 135 may be larger than that of the flow channel 135. E1 width of the flow path 135 E2 In one example, the ratio of the widths is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0133] Flow path 135 E1 one or more channels 135 for a width of M1 The ratio of the widths is, for example, 0.8 or more and 1.2 or less, and in one specific example, 0.9 or more and 1.1 or less.

[0134] Flow path 135 E2 The depth of the flow path 135 E1 The depth of the flow channel 135 may be greater than the depth of the flow channel 135. E1 flow path 135 for a depth of E2 The depth ratio is in one example greater than 1 and less than or equal to 1.5, and in one specific example greater than 1.1 and less than or equal to 1.4.

[0135] Flow path 135 E1 One or more channels 135 for a depth of M1 The depth ratio is, for example, 0.8 or more and 1.2 or less, and in one specific example, 0.9 or more and 1.1 or less.

[0136] In the first and second examples of FIGS. 6 to 9 , the most downstream flow passage group among the plurality of flow passage groups 130 is the flow passage group 130 N In the plurality of flow path groups 130, N The adjacent flow path group is flow path group 130 N-1 is.

[0137] As shown in FIGS. 6 and 8, the flow path group 130 N and flow path group 130 N-1 , rib 140 N-1 The flow path group 130 is partitioned byN A plurality of flow paths 135 in N is the flow path 135 E3 , flow path 135 E4 , and one or more flow channels 135 M2 Flow path 135 E3 is the flow path group 130 N The flow path 135 is at one end in the Z direction. E4 is the flow path group 130 N The flow path 135 is the flow path at the other end in the Z direction. E4 , rib 140 N-1 The one or more flow paths 135 are separated by M2 is the flow path 135 in the Z direction. E3 and flow path 135 E4 Located between.

[0138] Flow path 135 E3 and flow path 135 E4 may also be referred to as an end channel. M2 may also be referred to as an intermediate flow path. E4 is the proximal flow channel 111 N Flow path 135 M2 is the distal flow channel 120 N In the example of FIG. M2 In the example of FIG. 8, the number of flow paths 135 is one. M2 The number of is two.

[0139] Flow path 135 E4 The cross-sectional area of ​​the flow path is E3 The cross-sectional area of ​​the flow path 135 may be larger than that of the flow path 135. E3 Flow path 135 for the flow path cross-sectional area E4 The ratio of the cross-sectional areas of the flow passages is, in one example, greater than 1 and less than 1.5, and in one specific example, greater than 1.1 and less than 1.4.

[0140] Flow path 135 E3 One or more flow paths 135 for a flow path cross-sectional area of M2 The ratio of the cross-sectional areas of the flow paths is, for example, 0.8 or more and 1.2 or less, and in one specific example, 0.9 or more and 1.1 or less.

[0141] Flow path 135 E4The width of the flow path 135 E3 The width of the flow channel 135 may be larger than that of the flow channel 135. E3 width of the flow path 135 E4 In one example, the ratio of the widths is greater than 1 and less than or equal to 1.5, and in one specific example, greater than 1.1 and less than or equal to 1.4.

[0142] Flow path 135 E3 one or more channels 135 for a width of M2 The ratio of the widths is, for example, 0.8 or more and 1.2 or less, and in one specific example, 0.9 or more and 1.1 or less.

[0143] Flow path 135 E4 The depth of the flow path 135 E3 The depth of the flow channel 135 may be greater than the depth of the flow channel 135. E3 flow path 135 for a depth of E4 The depth ratio is in one example greater than 1 and less than or equal to 1.5, and in one specific example greater than 1.1 and less than or equal to 1.4.

[0144] Flow path 135 E3 One or more channels 135 for a depth of M2 The depth ratio is, for example, 0.8 or more and 1.2 or less, and in one specific example, 0.9 or more and 1.1 or less.

[0145] Various techniques can be applied to the configuration of the first embodiment.

[0146] The rib 140 may have a porous structure or a solid structure. A porous structure is advantageous from the viewpoint of supplying the reactive gas to the portion of the gas diffusion layer GDL facing the rib 140 by concentration diffusion. On the other hand, a solid structure is advantageous from the viewpoint of flowing the reactive gas along the reactive gas flow path FG. Similarly, the rib 150 may have a porous structure or a solid structure.

[0147] For all natural numbers j that satisfy 1≦j≦N, the flow path group 130 j A plurality of flow paths 135 in j a distal flow channel 120 included in j The number of the distal channels 121 may be three or more; j and the distal flow channel 122 j and an additional distal flow path 120j may exist.

[0148] For all natural numbers j that satisfy 1≦j≦N, the flow path group 130 j A plurality of flow paths 135 in j a distal flow channel 120 included in j When the number of the distal flow paths 120 is plural, j The cross-sectional areas of the distal channels 120 may be substantially the same. j The cross-sectional areas of the channels are substantially the same when the plurality of distal channels 120 are j The ratio of the maximum cross-sectional area of ​​the flow passage to the minimum cross-sectional area of ​​the flow passage is 0.8 or more and 1.2 or less. This ratio may be 0.9 or more and 1.1 or less.

[0149] In the following, each of the plurality of flow path groups 170 will be referred to as flow path group 170 1 , flow path group 170 2 , . . . , flow path group 170 N It is called.

[0150] The plurality of flow path groups 130 and the plurality of flow path groups 170 are represented by flow path group 130 1 , flow path group 170 1 , flow path group 130 2 , flow path group 170 2 , . . . , flow path group 170 N-1 , flow path group 130 N are connected in this order.

[0151] For all natural numbers j that satisfy 1≦j≦N−2, the flow path group 130 j+1 The relationship between the cross-sectional areas of the plurality of flow paths 135 in the flow path group 170 will be explained below. j The above-mentioned relationship may be applied to the size relationship of the cross-sectional areas of the plurality of flow paths 175 in the flow path group 130. j+1 The relationship between the widths of the plurality of flow paths 135 in the flow path group 170 will be explained below. j The widths of the plurality of flow paths 175 in the flow path group 130 may also be applied to the relationship between the widths of the plurality of flow paths 175 in the flow path group 130. j+1 The relationship between the depths of the plurality of flow paths 135 in the flow path group 170 will be explained below. j The above-mentioned application may be made by changing the reference numerals. The change may include changing "130" to "170" and changing "135" to "175".

[0152] After the above application, for all natural numbers j that satisfy 1≦j≦N−2, j+1 Among the plurality of flow paths 135 in the flow path group 170, the flow path 135 having a relatively large flow path cross-sectional area is j Among the plurality of flow paths 175 in the flow path group 130, the flow paths 175 having a relatively large flow path cross-sectional area are connected to each other, j+1 Among the plurality of flow paths 135 in the flow path group 170, the flow path 135 having a relatively small flow path cross-sectional area is j Among the plurality of flow paths 175 in the flow path group 130, the flow paths 175 having a relatively small flow path cross-sectional area are connected to each other, j+1 The flow path 135 having a relatively large width among the plurality of flow paths 135 in the flow path group 170 j The flow passages 175 having a relatively large width among the plurality of flow passages 175 in the flow passage group 130 are connected to each other, j+1 The flow path 135 having a relatively small width among the plurality of flow paths 135 in the flow path group 170 j The flow passages 175 having a relatively small width among the plurality of flow passages 175 in the flow passage group 130 are connected to each other, j+1 The flow path 135 having a relatively large depth among the plurality of flow paths 135 in the flow path group 170 j The flow passages 175 having a relatively large depth among the plurality of flow passages 175 in the flow passage group 130 are connected to each other, j+1 Among the plurality of flow paths 135 in the flow path group 170, the flow path 135 having a relatively small depth is j Among the plurality of flow paths 175 in the first and second regions, the flow paths 175 having a relatively small depth can be connected to each other.

[0153] In the above explanation, the configuration related to natural numbers j has been explained using expressions such as "for all natural numbers j that satisfy 1≦j≦N", "for all natural numbers j that satisfy 1≦j≦N-1", "for all natural numbers j that satisfy 1≦j≦N-2", etc. The configuration may be valid only for some of j, such as 1≦j≦N, 1≦j≦N-1, 1≦j≦N-2, etc.

[0154] [1-2. Operation] The operation and function of the fuel cell stack 200 configured as above will be explained below with reference to FIG.

[0155] A fuel gas, an oxidant gas, and a coolant are supplied to the fuel gas flow passage 40, the oxidant gas flow passage 50, and the coolant flow passage 60, respectively. The oxidant gas is typically air.

[0156] At the anode 13, hydrogen (H) is converted into protons (H + ) and electrons (e - ) The protons move from the anode 13 to the cathode 16 by conduction through the electrolyte membrane 12. The electrons move from the anode 13 to the cathode 16 through an external circuit. At the cathode 16, water (H2O) is produced by an electrochemical reaction of the protons, oxygen (O2), and electrons, as expressed by the following formula (2):

[0157] H2 → 2H + +2e - (1) 4H + + O2 + 2e - → 2H2O (2)

[0158] [1-3. Supplementary Notes] The above description of the embodiments discloses the following techniques.

[0159] (Technology 1) An electrochemical device comprising: an anode separator; a cathode separator; a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane, and disposed between the anode separator and the cathode separator; a fuel gas flow channel provided between the anode and the anode separator; and an oxidant gas flow channel provided between the cathode and the cathode separator, wherein at least one of the fuel gas flow channel and the oxidant gas flow channel has, from upstream to downstream in a flow direction of a reactive gas which is a fuel gas or an oxidant gas, a first flow channel group, a second flow channel group, and a third flow channel group, in this order, from upstream to downstream in a flow direction of a reactive gas which is a fuel gas or an oxidant gas, wherein the first flow channel group and the second flow channel group are flow channel groups which allow the reactive gas to flow in opposite directions to each other and are separated by a first rib; and the second flow channel group and the third flow channel group are flow channel groups which allow the reactive gas to flow in opposite directions to each other and are separated by a second rib. A fuel cell, wherein the second flow path group includes a first proximal flow path, a second proximal flow path, and at least one distal flow path, wherein the first proximal flow path is partitioned by the first rib, and the second proximal flow path is partitioned by the second rib, and (i) the one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a flow path cross-sectional area of ​​the first proximal flow path is larger than a flow path cross-sectional area of ​​the one distal flow path, and a flow path cross-sectional area of ​​the second proximal flow path is larger than a flow path cross-sectional area of ​​the one distal flow path, or (ii) the at least one distal flow path includes a first distal flow path and a second distal flow path, wherein the first distal flow path is a flow path adjacent to the first proximal flow path and the second distal flow path is a flow path adjacent to the second proximal flow path, and a flow path cross-sectional area of ​​the first proximal flow path is larger than a flow path cross-sectional area of ​​the first distal flow path, and a flow path cross-sectional area of ​​the second proximal flow path is larger than a flow path cross-sectional area of ​​the second distal flow path.

[0160] (Technology 2) At least one of the fuel gas flow path and the oxidant gas flow path has a plurality of flow path groups arranged in an arrangement direction so as to be parallel to each other, the plurality of flow path groups including the first flow path group, the second flow path group, and the third flow path group, (x1) an upstream flow path group of the plurality of flow path groups is separated from an adjacent flow path group of the plurality of flow path groups by a first partition rib and includes a first end flow path that is an end flow path in the most upstream flow path group in the arrangement direction, and includes a second end flow path that is an end flow path in the most upstream flow path group in the arrangement direction, partitioned by the first partition rib, and has a flow path cross-sectional area larger than that of the first end flow path, and / or (y1) a downstream flow path group of the plurality of flow path groups is separated from an adjacent flow path group of the plurality of flow path groups by a second partition rib and includes a third end flow path that is an end flow path in the most downstream flow path group in the arrangement direction, a fourth end flow path that is a flow path at the other end in the arrangement direction in the most downstream flow path group, the fourth end flow path being a flow path that is partitioned by the second partition rib and has a flow path cross-sectional area larger than that of the third end flow path.

[0161] (Technology 3) At least one of the fuel gas flow path and the oxidant gas flow path has a plurality of flow path groups arranged in an arrangement direction so as to be parallel to each other, the plurality of flow path groups including the first flow path group, the second flow path group, and the third flow path group; (x2) a most upstream flow path group of the plurality of flow path groups is separated from a flow path group adjacent to the most upstream flow path group by a first partition rib, and includes a first end flow path that is an end flow path in the most upstream flow path group in the arrangement direction, and includes a second end flow path that is an other end flow path in the most upstream flow path group in the arrangement direction and partitioned by the first partition rib; and includes a first one or more intermediate flow paths located between the first end flow path and the second end flow path in the arrangement direction, the ratio of a flow path cross-sectional area of ​​the first one or more intermediate flow paths to a flow path cross-sectional area of ​​the first end flow path being 0.8 or more and 1.2 or less; and / or (y2) a most downstream flow path group of the plurality of flow path groups is a third end flow path that is separated from a flow path group adjacent to the most downstream flow path group among the plurality of flow path groups by a second partition rib, and that is a flow path at one end in the most downstream flow path group in the arrangement direction; a fourth end flow path that is a flow path at the other end in the most downstream flow path group in the arrangement direction and that is partitioned by the second partition rib; and a second one or more intermediate flow paths located between the third end flow path and the fourth end flow path in the arrangement direction, wherein a ratio of a flow path cross-sectional area of ​​the second one or more intermediate flow paths to a flow path cross-sectional area of ​​the third end flow path is 0.8 or more and 1.2 or less.

[0162] (Technology 4) The fuel cell according to any one of Technologies 1 to 3, wherein: (ia) the one distal flow path is adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a ratio of a flow path cross-sectional area of ​​the first proximal flow path to a flow path cross-sectional area of ​​the one distal flow path is greater than 1 and not greater than 1.5, and / or a ratio of a flow path cross-sectional area of ​​the second proximal flow path to a flow path cross-sectional area of ​​the one distal flow path is greater than 1 and not greater than 1.5, or (iia) the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path is adjacent to the first proximal flow path, and the second distal flow path is adjacent to the second proximal flow path, and a ratio of a flow path cross-sectional area of ​​the first proximal flow path to a flow path cross-sectional area of ​​the first distal flow path is greater than 1 and not greater than 1.5, and / or a ratio of a flow path cross-sectional area of ​​the second proximal flow path to a flow path cross-sectional area of ​​the second distal flow path is greater than 1 and not greater than 1.5.

[0163] (Technology 5) A fuel cell described in any one of Technologies 1 to 4, wherein (ib) the one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a width of the first proximal flow path is larger than a width of the one distal flow path and / or a width of the second proximal flow path is larger than a width of the one distal flow path, or (iib) the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path is a flow path adjacent to the first proximal flow path and the second distal flow path is a flow path adjacent to the second proximal flow path, and a width of the first proximal flow path is larger than a width of the first distal flow path and / or a width of the second proximal flow path is larger than a width of the second distal flow path.

[0164] (Technology 6) A fuel cell described in any one of Technologies 1 to 5, wherein: (ic) the one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a depth of the first proximal flow path is greater than a depth of the one distal flow path and / or a depth of the second proximal flow path is greater than a depth of the one distal flow path, or (iic) the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path is a flow path adjacent to the first proximal flow path and the second distal flow path is a flow path adjacent to the second proximal flow path, and a depth of the first proximal flow path is greater than a depth of the first distal flow path and / or a depth of the second proximal flow path is greater than a depth of the second distal flow path.

[0165] (Technology 7) (id) The one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and the ratio of the width of the first rib to the width of a first intermediate rib located between the first proximal flow path and the one distal flow path is greater than 0.7 and less than 1.3, and / or the ratio of the width of the second rib to the width of a second intermediate rib located between the second proximal flow path and the one distal flow path is greater than 0.7 and less than 1.3, or (iid) The fuel cell described in any one of techniques 1 to 6, wherein the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path being adjacent to the first proximal flow path, and the second distal flow path being adjacent to the second proximal flow path, and wherein a ratio of a width of the first rib to a width of a third intermediate rib located between the first proximal flow path and the first distal flow path is greater than 0.7 and less than 1.3, and / or a ratio of a width of the second rib to a width of a fourth intermediate rib located between the second proximal flow path and the second distal flow path is greater than 0.7 and less than 1.3.

[0166] (Technology 8) The fuel cell according to any one of Technology 1 to Technology 7, wherein a width of an opening of the first proximal flow path is larger than a width of a bottom of the first proximal flow path, and / or a width of an opening of the second proximal flow path is larger than a width of a bottom of the second proximal flow path.

[0167] (Technology 9) The fuel cell according to any one of Technology 1 to Technology 8, wherein at least one of the fuel gas flow path and the oxidant gas flow path has a plurality of flow path groups arranged in parallel to each other and a specific flow path group, wherein the plurality of flow path groups include the first flow path group, the second flow path group, and the third flow path group, and wherein the specific flow path group connects two adjacent flow path groups in the plurality of flow path groups, and includes a first throttle flow path communicating with the first proximal flow path and including a first throttle, and / or a second throttle flow path communicating with the second proximal flow path and including a second throttle.

[0168] (Technology 10) The fuel cell according to any one of Technology 1 to Technology 9, wherein at least one of the fuel gas flow path and the oxidant gas flow path is a serpentine flow path, and the serpentine flow path has a plurality of flow path groups arranged parallel to each other, the plurality of flow path groups including the first flow path group, the second flow path group, and the third flow path group.

[0169] According to the technology of the present disclosure, a fuel cell with high power generation can be realized.

Claims

1. An electrochemical device comprising: an anode separator; a cathode separator; a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane, and disposed between the anode separator and the cathode separator; a fuel gas flow path provided between the anode and the anode separator; and an oxidant gas flow path provided between the cathode and the cathode separator, wherein at least one of the fuel gas flow path and the oxidant gas flow path has, from upstream to downstream in the flow direction of a reactive gas which is a fuel gas or an oxidant gas, a first flow path group, a second flow path group, and a third flow path group, in this order; the first flow path group and the second flow path group are flow path groups which allow the reactive gas to flow in opposite directions to each other and are separated by a first rib; and the second flow path group and the third flow path group are flow path groups which allow the reactive gas to flow in opposite directions to each other and are separated by a second rib. A fuel cell, wherein the second flow path group includes a first proximal flow path, a second proximal flow path, and at least one distal flow path, wherein the first proximal flow path is partitioned by the first rib, and the second proximal flow path is partitioned by the second rib, and (i) the one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a flow path cross-sectional area of the first proximal flow path is larger than a flow path cross-sectional area of the one distal flow path, and a flow path cross-sectional area of the second proximal flow path is larger than a flow path cross-sectional area of the one distal flow path, or (ii) the at least one distal flow path includes a first distal flow path and a second distal flow path, wherein the first distal flow path is a flow path adjacent to the first proximal flow path and the second distal flow path is a flow path adjacent to the second proximal flow path, and a flow path cross-sectional area of the first proximal flow path is larger than a flow path cross-sectional area of the first distal flow path, and a flow path cross-sectional area of the second proximal flow path is larger than a flow path cross-sectional area of the second distal flow path.

2. At least one of the fuel gas flow path and the oxidant gas flow path has a plurality of flow path groups arranged in a line direction so as to be parallel to each other, the plurality of flow path groups including the first flow path group, the second flow path group, and the third flow path group, (x1) an upstream flow path group of the plurality of flow path groups is separated from a flow path group adjacent to the upstream flow path group of the plurality of flow path groups by a first partition rib and includes a first end flow path which is an end flow path in the most upstream flow path group in the line direction, and includes a second end flow path which is an end flow path in the most upstream flow path group in the line direction, partitioned by the first partition rib, and has a larger flow path cross-sectional area than the first end flow path, and / or (y1) a downstream flow path group of the plurality of flow path groups is separated from a flow path group adjacent to the downstream flow path group of the plurality of flow path groups by a second partition rib and includes a third end flow path which is an end flow path in the most downstream flow path group in the line direction, 2. The fuel cell according to claim 1, further comprising a fourth end flow path, which is a flow path at the other end in the arrangement direction in the most downstream flow path group, partitioned by the second partition rib and having a flow path cross-sectional area larger than that of the third end flow path.

3. At least one of the fuel gas flow path and the oxidant gas flow path has a plurality of flow path groups arranged in a lining direction so as to be parallel to each other, the plurality of flow path groups including the first flow path group, the second flow path group, and the third flow path group; (x2) a most upstream flow path group of the plurality of flow path groups is separated from a flow path group adjacent to the most upstream flow path group by a first partition rib, and includes a first end flow path that is an end flow path in the most upstream flow path group in the lining direction, and includes a second end flow path that is an other end flow path in the most upstream flow path group in the lining direction and is partitioned by the first partition rib; and includes a first one or more intermediate flow paths located between the first end flow path and the second end flow path in the lining direction, the ratio of a flow path cross-sectional area of the first one or more intermediate flow paths to a flow path cross-sectional area of the first end flow path being 0.8 or more and 1.2 or less; and / or (y2) a most downstream flow path group of the plurality of flow path groups is 2. The fuel cell according to claim 1, wherein the fuel cell comprises: a third end flow path separated from an adjacent flow path group to the most downstream flow path group among the plurality of flow path groups by a second partition rib; a fourth end flow path that is an end flow path in the most downstream flow path group in the arrangement direction; and a second one or more intermediate flow paths located between the third end flow path and the fourth end flow path in the arrangement direction, the second one or more intermediate flow paths having a ratio of a flow path cross-sectional area of the second one or more intermediate flow paths to a flow path cross-sectional area of the third end flow path being 0.8 or more and 1.2 or less.

4. The fuel cell of claim 1, wherein: (ia) the one distal flow path is adjacent to the first proximal flow path and adjacent to the second proximal flow path, and a ratio of a flow path cross-sectional area of the first proximal flow path to a flow path cross-sectional area of the one distal flow path is greater than 1 and not greater than 1.5 and / or a ratio of a flow path cross-sectional area of the second proximal flow path to a flow path cross-sectional area of the one distal flow path is greater than 1 and not greater than 1.5; or (iia) the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path is adjacent to the first proximal flow path and the second distal flow path is adjacent to the second proximal flow path, and a ratio of a flow path cross-sectional area of the first proximal flow path to a flow path cross-sectional area of the first distal flow path is greater than 1 and not greater than 1.5 and / or a ratio of a flow path cross-sectional area of the second proximal flow path to a flow path cross-sectional area of the second distal flow path is greater than 1 and not greater than 1.

5.

5. The fuel cell described in claim 1, wherein: (ib) the one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and the width of the first proximal flow path is greater than the width of the one distal flow path and / or the width of the second proximal flow path is greater than the width of the one distal flow path, or (iib) the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path is a flow path adjacent to the first proximal flow path and the second distal flow path is a flow path adjacent to the second proximal flow path, and the width of the first proximal flow path is greater than the width of the first distal flow path and / or the width of the second proximal flow path is greater than the width of the second distal flow path.

6. The fuel cell of claim 1, wherein: (ic) the one distal flow path is adjacent to the first proximal flow path and adjacent to the second proximal flow path, and the depth of the first proximal flow path is greater than the depth of the one distal flow path and / or the depth of the second proximal flow path is greater than the depth of the one distal flow path; or (iic) the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path is adjacent to the first proximal flow path and the second distal flow path is adjacent to the second proximal flow path, and the depth of the first proximal flow path is greater than the depth of the first distal flow path and / or the depth of the second proximal flow path is greater than the depth of the second distal flow path.

7. (id) The one distal flow path is a flow path adjacent to the first proximal flow path and adjacent to the second proximal flow path, and the ratio of the width of the first rib to the width of a first intermediate rib located between the first proximal flow path and the one distal flow path is greater than 0.7 and less than 1.3, and / or the ratio of the width of the second rib to the width of a second intermediate rib located between the second proximal flow path and the one distal flow path is greater than 0.7 and less than 1.3, or (iid) The fuel cell described in claim 1, wherein the at least one distal flow path includes a first distal flow path and a second distal flow path, the first distal flow path being adjacent to the first proximal flow path, and the second distal flow path being adjacent to the second proximal flow path, and wherein a ratio of the width of the first rib to the width of a third intermediate rib located between the first proximal flow path and the first distal flow path is greater than 0.7 and less than 1.3, and / or a ratio of the width of the second rib to the width of a fourth intermediate rib located between the second proximal flow path and the second distal flow path is greater than 0.7 and less than 1.

3.

8. The fuel cell according to claim 1, wherein the width of the opening of the first proximal flow path is greater than the width of the bottom of the first proximal flow path, and / or the width of the opening of the second proximal flow path is greater than the width of the bottom of the second proximal flow path.

9. The fuel cell according to claim 1, wherein at least one of the fuel gas flow path and the oxidant gas flow path has a plurality of flow path groups arranged in parallel to each other and a specific flow path group, wherein the plurality of flow path groups include the first flow path group, the second flow path group, and the third flow path group, and wherein the specific flow path group connects two adjacent flow path groups in the plurality of flow path groups and includes a first throttle flow path that communicates with the first proximal flow path and includes a first throttle, and / or a second throttle flow path that communicates with the second proximal flow path and includes a second throttle.

10. A fuel cell according to any one of claims 1 to 9, wherein at least one of the fuel gas flow path and the oxidant gas flow path is a serpentine flow path, and the serpentine flow path has a plurality of flow path groups arranged in parallel to each other, the plurality of flow path groups including the first flow path group, the second flow path group, and the third flow path group.

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