Power generation cell

Abstract

To provide a power generation cell capable of surely preventing a leakage of a reaction gas while regulating a bypass flow of the reaction gas flowing so as to avoid a power generation region with high efficiency.SOLUTION: In a power generation cell C, a wave shaped reaction gas flow passage 21 in which a reaction gas flows along an electrolyte film and an electrode structure toward the other end side from a one end side of a separator 2, and a seal part 24 that prevents a leakage of the reaction gas by surrounding the reaction gas flow passage 21 in a state where it is contacted to a resin frame part of the electrolyte film and an electrode structure. The seal part 24 includes a plurality of top parts 21a1 that is convex toward the reaction gas flow passage 21 side, and a top part 21a1 that is convex toward the seal part 24 side of the reaction gas flow passage 21 is positioned onto a straight line L connecting between the adjacent two top parts 24a1 of the seal part 24 or is projected to the seal part 24 side that exceeds the straight line L.SELECTED DRAWING: Figure 6C

Description

[Technical field]

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

[0002] In recent years, research has been conducted into fuel cells as a contribution to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy. Conventionally, a bipolar plate for a fuel cell having a channel structure in which a plurality of reactant gas flow paths are arranged in parallel along the electrochemically active region of a polymer electrolyte membrane is known (see, for example, Patent Document 1). This bipolar plate has a boundary wall (sealing portion) formed along the periphery, and a restricting member made of a rib that prevents the flow (bypass flow) of the reactant gas between the boundary wall and the channel structure. In such a fuel cell, the restricting member blocks the bypass flow of the reactant gas that attempts to flow between the channel structure and the boundary wall to avoid the power generation region, thereby increasing the reaction rate of the reactant gas in the power generation region of the fuel cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5239091 Summary of the Invention [Problem to be solved by the invention]

[0004] In general, the reaction gas flow paths of a bipolar plate are formed as grooves (channel structures) on the plate surface when the bipolar plate is produced by press molding a plate. In recent fuel cells, the power generation area is becoming larger and the pitch of the reactant gas flow passages is becoming finer. This can cause the bipolar plate to bend due to excess material in the press forming process. When such a bipolar plate is used to construct a conventional fuel cell stack (see, for example, Patent Document 1), the surface pressure of the bipolar plate against the polymer electrolyte membrane in the power generation region varies, making it easier for the reactant gas to leak from the reactant gas flow path. In addition, since the restricting member of the bipolar plate that blocks the bypass flow is formed to connect the boundary wall and the outer periphery of the channel structure, there is a concern that the reactant gas may leak from the boundary wall (sealing portion) due to a step between the boundary wall and the channel structure caused by the bending of the bipolar plate (separator).

[0005] An object of the present invention is to provide a power generation cell that can efficiently regulate the bypass flow of the reactant gas that flows to avoid the power generation region and can more reliably prevent the reactant gas from leaking, thereby contributing to improved energy efficiency. [Means for solving the problem]

[0006] The power generation cell of the present invention which achieves the above-mentioned object is a power generation cell comprising an electrolyte membrane-electrode assembly having electrodes provided on both sides of an electrolyte membrane, a resin frame provided on the outer periphery of the electrolyte membrane-electrode assembly, and separators arranged on both sides of the electrolyte membrane-electrode assembly, wherein the separators are plate-shaped components made of metal and are provided with a wavy-line-shaped reactant gas flow path which allows a reactant gas to flow along the electrolyte membrane-electrode assembly from one end to the other end of the separator, and a seal portion which surrounds the reactant gas flow path while in contact with the resin frame to prevent leakage of the reactant gas, wherein the seal portion has a plurality of apexes which are convex toward the reactant gas flow path side, and the apexes of the reactant gas flow path which are convex toward the seal portion side are located on a straight line connecting two adjacent apexes of the seal portion or protrude beyond the straight line toward the seal portion side.

[0007] The power generation cell of the present invention is a power generation cell comprising an electrolyte membrane-electrode assembly having electrodes provided on both sides of an electrolyte membrane, a resin frame provided on the outer periphery of the electrolyte membrane-electrode assembly, and separators arranged on both sides of the electrolyte membrane-electrode assembly, the separators being plate-shaped parts made of metal and provided with a wavy-line-shaped reactant gas flow path for flowing a reactant gas along the electrolyte membrane-electrode assembly from one end to the other end of the separator, and a seal portion that surrounds the reactant gas flow path while in contact with the resin frame to prevent leakage of the reactant gas, the seal portion having an apex that is convex toward the reactant gas flow path, and the apex of the reactant gas flow path that is convex toward the seal portion is formed in a position opposite to the apex of the seal portion that is convex toward the reactant gas flow path. Effect of the Invention

[0008] According to the power generating cell of the present invention, it is possible to efficiently regulate the bypass flow of the reactant gas that flows to avoid the power generating region, while more reliably preventing the reactant gas from leaking. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is an exploded perspective view of a power generating cell according to an embodiment of the present invention. [Diagram 2] 2 is a partially enlarged plan view of a power generating cell corresponding to the position of the part indicated by arrow II in FIG. [Figure 3A] FIG. 3 is a cross-sectional view taken along line IIIA-IIIA of FIG. 2. [Figure 3B] FIG. 3 is a cross-sectional view taken along line IIIB-IIIB of FIG. 2. [Figure 4] FIG. 3C is a cross-sectional view of a modified example of the membrane electrode assembly shown in FIG. 3B. [Diagram 5] FIG. 2 is a plan view of the separator as viewed from the membrane electrode assembly side. [Figure 6A] FIG. 6 is a partial enlarged view of a VIA portion in FIG. 5. [Figure 6B] FIG. 6 is a partial enlarged view of part VIB in FIG. 5. [Figure 6C]4 is a partially enlarged plan view of the separator, showing how a recess in a seal portion of the separator faces a protrusion in a reactant gas flow path. FIG. [Figure 7] FIG. 4 is a partially enlarged plan view of a power generating cell according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Next, a mode (embodiment) for carrying out the power generating cell of the present invention will be described in detail with reference to the drawings as appropriate. The power generation cell of this embodiment is mainly characterized in that a separator is provided with multiple wavy reactant gas flow paths that meander in one direction on the surface of a membrane electrode assembly (MEA) so as to be arranged in parallel, and a convex portion of the wavy reactant gas flow path is arranged close to a reactant gas seal portion provided along the periphery of the separator, thereby forming a bypass flow restriction portion for the reactant gas. Below, the overall configuration of the power generating cell will be explained, followed by an explanation of the membrane electrode assembly and the separator.

[0011] <Overall configuration of power generation cell> Fig. 1 is an exploded perspective view of a power generating cell C. Note that the front-rear, up-down, left-right directions in the following description are based on the front-rear, up-down, left-right directions indicated by the arrows in Fig. 1. However, the front-rear, up-down, left-right directions shown in Fig. 1 are set for the sake of convenience in specifically explaining the configuration of each part in the power generating cell C, and do not indicate absolute directions in the power generating cell C.

[0012] As shown in FIG. 1, the power generation cell C is constituted by a unit cell consisting of a membrane electrode assembly 1 and a pair of separators (a cathode side separator 2 and an anode side separator 3) that sandwich the membrane electrode assembly 1. The fuel cell is used as a fuel cell stack having a cell unit (not shown) in which such power generation cells C (unit cells) are stacked in the front-rear direction. The cell unit in this embodiment is assumed to be, for example, an electrolyte membrane-electrode structure (not shown) having a cathode-side separator 2 arranged side by side on the cathode side of the electrolyte membrane-electrode structure 1 shown in Fig. 1, an anode-side separator 3 arranged back-to-back to the cathode-side separator 2, and an electrolyte membrane-electrode structure (not shown) arranged with the anode side facing the anode-side separator 3.

[0013] Furthermore, the anode-side separator 3, which is disposed on the anode side of the electrolyte membrane-electrode assembly 1 shown in FIG. 1, is disposed with the cathode-side separator 2, which is disposed back-to-back, interposing therebetween, so that the cathode side of the electrolyte membrane-electrode assembly 1 (not shown) faces the cathode-side separator 2. In FIG. 1, reference symbol 10a denotes a reaction gas supply port for supplying an oxygen-containing gas (oxidizer gas), reference symbol 10b denotes a reaction gas exhaust port for discharging a hydrogen-containing gas (fuel gas), and reference symbol 10c denotes a cooling medium supply port for supplying a cooling medium (e.g., water, oil, etc.). In addition, in FIG. 1, reference symbol 10d is a reaction gas outlet port for discharging an oxygen-containing gas (oxidizer gas), reference symbol 10e is a reaction gas supply port for supplying a hydrogen-containing gas (fuel gas), and reference symbol 10f is a cooling medium outlet port for discharging a cooling medium.

[0014] The reactant gas supply ports 10a, 10e, the reactant gas exhaust ports 10d, 10b, the cooling medium supply port 10c, and the cooling medium exhaust port 10f are formed in the membrane electrode assembly 1, the cathode separator 2, and the anode separator 3. When a plurality of power generating cells C are stacked, the reactant gas supply ports 10a, 10e, the reactant gas exhaust ports 10d, 10b, the cooling medium supply port 10c, and the cooling medium exhaust port 10f are united to form a communication hole 10 extending in the front-rear direction.

[0015] The number of stacks of such power generating cells C (unit cells) can be set according to the required power generation capacity of the fuel cell. Incidentally, the fuel cell in this embodiment is assumed to be a fuel cell having several hundred cells connected in series, but is not limited to this. In this embodiment, the cathode side separator 2 and the anode side separator 3 are previously joined together back to back by welding or the like.

[0016] Although not shown in the figures, a fuel cell using such a power generating cell C has a terminal plate, an insulating plate, and an end plate, in this order, from the cell unit side toward the outside, at both ends of a cell unit consisting of multiple power generating cells C (unit cells). The multiple sets of power generating cells that make up the cell unit are fastened together with a predetermined load between the end plates at both ends. As a result, the cathode side separator 2 and the anode side separator 3 sandwich the electrolyte membrane electrode assembly 1 under a predetermined load, with the reactant gas flow channel 21 (see FIG. 3A) and the reactant gas flow channel 31 (see FIG. 3A) facing inwards.

[0017] Fig. 2 is a partially enlarged plan view of the power generating cell C (unit cell) corresponding to the position of the part indicated by the arrow II in Fig. 1. Specifically, Fig. 2 is a partially enlarged plan view of the back surface of the cathode-side separator 2 in the power generating cell C. Fig. 3A is a cross-sectional view taken along IIIA-IIIA of the power generating cell C shown in Fig. 2. Fig. 3A is a cross-sectional view taken along the line IIIA-IIIA of the power generating cell C shown in Fig. 2, in a front view (front view) of the power generating cell C, at the center position of a protrusion 21a of a reactant gas flow channel 21 described later. Fig. 3B is a cross-sectional view taken along the line IIIB-IIIB of the power generating cell C shown in Fig. 2 ..., in a front view (front view) of the power generating cell C, at the center position of a recess 21b of a reactant gas flow channel 21 described later.

[0018] As shown in FIG. 2, the back surface of the cathode side separator 2 which constitutes the front surface of the power generating cell C is configured with an inverted uneven shape of a groove-shaped reactant gas flow passage 21 (see FIG. 3A), which will be described in detail later, a bead-shaped seal portion 24 (see FIG. 3A), and a groove-shaped bypass flow passage 25 (see FIG. 3A). This inverted uneven shape is formed when a metal plate is press-molded to produce the cathode side separator 2, and the uneven shapes of the reaction gas flow path 21 (see Figure 3A), the seal portion 24 (see Figure 3A), and the bypass flow path 25 (see Figure 3A) are inverted on the front and back (front and back) of the cathode side separator 2. As will be described in detail later, the back surface of the anode side separator 3 (see FIG. 1) which forms the rear surface of the power generation cell C also has the inverted uneven shapes of the reactant gas flow passage 31 (see FIG. 3A), the seal portion 34 (see FIG. 3A), and the bypass flow passage 35 (see FIG. 3A).

[0019] ≪Electrolyte membrane / electrode structure≫ As shown in FIG. 1, the membrane electrode assembly 1 is formed of a thin plate having a rectangular planar shape that is long in the left-right direction. When viewed from the front (front view), the electrolyte membrane / electrode structure 1 has a rectangular electrolyte membrane / electrode part 5 in the center, and a resin frame part 13 that forms the outer periphery of the electrolyte membrane / electrode structure 1 and borders the periphery of this electrolyte membrane / electrode part 5.

[0020] In this embodiment, the reactive gas supply port 10a, the reactive gas supply port 10b, and the cooling medium supply port 10c are formed at the left end of the resin frame 13. Also, the reactive gas exhaust port 10d, the reactive gas exhaust port 10e, and the cooling medium exhaust port 10f are formed at the right end of the resin frame 13. The material for such resin frame 13 is not particularly limited as long as it is a proton non-conductive resin and has a predetermined heat resistance, but an engineering plastic film such as polyphenylene sulfide (PPS) is preferable.

[0021] The electrolyte membrane-electrode part 5 (see FIG. 1) constituting the electrolyte membrane-electrode structure 1 is configured to have an electrolyte membrane 11, a cathode 12a (oxygen electrode) formed on one surface of the electrolyte membrane 11, and an anode 12b (fuel electrode) formed on the other surface, as shown in FIGS. 3A and 3B. The electrolyte membrane 11 in this embodiment is assumed to be a proton exchange membrane made of a polymer solid electrolyte.

[0022] Although not shown in the figure, the cathode 12a and the anode 12b are each configured to include a gas diffusion layer made of carbon paper or the like, and a catalyst layer formed by applying an ion-conductive resin composition containing a catalyst such as platinum to the surface of the gas diffusion layer on the side in contact with the electrolyte membrane 11. In this embodiment, the cathode 12a and the anode 12b are each partially overlapped with a resin frame 13 that forms the outer periphery of the membrane electrode assembly 1, as shown in FIGS. 3A and 3B. Specifically, in this embodiment, the outer edge portions (upper edge portions in Figures 3A and 3B) of the cathode 12a and the anode 12b are arranged so as to sandwich the inner edge portion (lower edge portion in Figures 3A and 3B) of the resin frame portion 13 in the front-to-rear direction.

[0023] In such a membrane electrode assembly 1, as shown in FIGS. 3A and 3B, the region where the cathode 12a and the anode 12b sandwich the electrolyte membrane 11 forms an electrochemically active power generation region A1. Incidentally, a hydrogen-containing gas (fuel gas) is supplied to the anode 12b constituting this power generation region A1 from a first reactant gas flow channel 32, which will be described in detail later. Hydrogen that reaches a catalyst layer (not shown) through a gas diffusion layer (not shown) of the anode 12b is decomposed into electrons and protons. The electrons are taken out to an external circuit connected to the anode 12b, and the protons pass through the electrolyte membrane 11 to reach a catalyst layer (not shown) of the cathode 12a constituting the power generation region A1.

[0024] On the other hand, an oxygen-containing gas (oxidant gas) is supplied to the cathode 12a from a first reactant gas flow channel 22, which will be described in detail later. The oxygen reaches a catalyst layer (not shown) through a gas diffusion layer of the cathode 12a. In the catalyst layer of the cathode 12a, protons arriving from the electrolyte membrane 11 side, oxygen, and electrons arriving via an external circuit combine to generate water. The flow of electrons extracted to the external circuit during this series of processes is used as generated electricity. As shown in FIGS. 3A and 3B, the region between the cathode 12a and the anode 12b in which the proton non-conductive resin frame 13 is disposed becomes a non-power generation region A2 that does not contribute to power generation.

[0025] FIG. 4 is a cross-sectional view of a membrane electrode assembly 1A which is a modified example of the membrane electrode assembly 1 (see FIGS. 3A and 3B). FIG. 4 corresponds to FIG. 3B. In FIG. 4, the same components as those in the membrane electrode assembly 1 (see FIG. 3B) are given the same reference numerals and detailed description thereof will be omitted. FIG. 4 shows a schematic view of the membrane electrode assembly 1A in a state where the power generation cells C (see FIG. 1) are stacked and a predetermined load is applied between the cathode side separator 2 and the anode side separator 3.

[0026] As shown in FIG. 4, the resin frame 13 constituting the outer periphery of the membrane electrode assembly 1A is made up of a resin frame 13a and a resin frame 13b. Specifically, the resin frame portion 13 is configured to have a resin frame portion 13a arranged adjacent to the cathode side separator 2, and a resin frame portion 13b arranged adjacent to the anode side separator 3. The electrolyte membrane 11 of the membrane electrode assembly 1A is disposed between the cathode 12a and the anode 12b so as to extend to the edges of the cathode 12a and the anode 12b. That is, the cathode 12a and the anode 12b are formed and disposed so as to correspond to the membrane surface of the electrolyte membrane 11.

[0027] The resin frame portion 13a is disposed so as to be sandwiched between an end portion of the cathode 12a and an end portion of the electrolyte membrane 11. The cathode 12a and the electrolyte membrane 11 are bonded to the resin frame portion 13a at portions that sandwich the resin frame portion 13a. Moreover, the resin frame portion 13b is disposed so as to be sandwiched between an end portion of the anode 12b and an end portion of the electrolyte membrane 11. The anode 12b and the electrolyte membrane 11 are bonded to the resin frame portion 13b at portions that sandwich the resin frame portion 13b.

[0028] The length over which the resin frame portion 13b is sandwiched between the anode 12b and the electrolyte membrane 11 is longer than the length over which the resin frame portion 13a is sandwiched between the cathode 12a and the electrolyte membrane 11. Resin frame portion 13a and resin frame portion 13b are bonded together and integrated, except for the portion disposed between cathode 12a and anode 12b.

[0029] In such a membrane electrode assembly 1A, the region where the cathode 12a and the anode 12b sandwich the electrolyte membrane 11 forms an electrochemically active power generation region A1, as shown in Fig. 4. The region where at least one of the resin frame 13a and the resin frame 13b (the resin frame 13b in Fig. 4) is disposed between the cathode 12a and the anode 12b forms a non-power generation region A2 that does not contribute to power generation.

[0030] 4, in such a membrane electrode assembly 1A, the resin frame 13a and the resin frame 13b are disposed between the cathode 12a and the anode 12b so as to sandwich the electrolyte membrane 11. This further improves the bonding strength of the resin frame 13 in the membrane electrode assembly 1A.

[0031] 4 is configured assuming that the thickness in the stacking direction of a portion having the resin frame portions 13a, 13b between the cathode 12a and the anode 12b is greater than that of a portion not having the resin frame portions 13a, 13b. Specifically, the electrolyte membrane electrode assembly 1A has a step of width D between the portion having the resin frame portions 13a, 13b between the cathode 12a and the anode 12b and the portion not having the resin frame portions 13a, 13b. That is, the membrane electrode assembly 1A allows some variation in thickness depending on, for example, the designed compression allowance of the gas diffusion layers used in the cathode 12a and anode 12b during stacking.

[0032] 4, it is assumed that a gradient S occurs in a section from a portion having the resin frame portions 13a, 13b to a portion not having the resin frame portions 13a, 13b. This gradient S is configured to be formed mainly toward the anode 12b side rather than the cathode 12a side.

[0033] Furthermore, the membrane electrode assembly 1A has a gradual transition from a portion having the resin frames 13a, 13b to a portion not having the resin frames 13a, 13b. Specifically, the resin frame 13b disposed between the cathode 12a and the anode 12b is longer than the resin frame 13a.

[0034] On the other hand, the cathode side separator 2 and the anode side separator 3 that sandwich the membrane electrode assembly 1A are elastically deformed by the load when stacked and are pressed against the membrane electrode assembly 1A. That is, in the portion having the resin frame 13 between the cathode 12a and the anode 12b, the anode separator 3 is pressed against the membrane electrode assembly 1A at the bead portion B1 formed between the reactant gas channels 31. In the portion between the cathode 12 a and the anode 12 b where the resin frame 13 is not present, the anode separator 3 is pressed against the membrane electrode assembly 1 A at the bead portion B 2 formed between the reactant gas channels 31 .

[0035] In order to maintain the same surface pressure on the membrane electrode assembly 1A as that of the bead portion B2, the bead portion B1 is designed such that its contact surface with the membrane electrode assembly 1A is displaced in a direction away from the membrane electrode assembly 1A relative to the contact surface of the bead portion B2. In other words, the anode-side separator 3 has a step of width D between the bead portion B1 and the bead portion B2. On the other hand, the beads of the cathode side separator 2 do not have any steps and are disposed flush with each other.

[0036] As will be described in detail later, the anode side separator 3 is assumed to have a larger flow channel cross-sectional area and a longer pitch for the reactant gas flow channels 31 than the reactant gas flow channels 21 of the cathode side separator 2. This gives the anode side separator 3 greater elastic deformation ability than the cathode side separator 2 when pressed against the membrane electrode assembly 1A. That is, the membrane electrode assembly 1A ensures good sealing between adjacent reactant gas channels 31 by forming the gradient S on the anode separator 3 side, which has a high degree of elastic deformation when pressed against the membrane electrode assembly 1A.

[0037] <Separator> As shown in Fig. 2, the reactant gas flow channel 21 of the cathode-side separator 2 extends from one end side to the other end side of the cathode-side separator 2. Specifically, the reactant gas flow channel 21 is formed in a wavy line shape with a constant wavelength and a constant amplitude when viewed from the front (front view) of the power generating cell C shown in Fig. 2. The waveform of the reactant gas flow passage 21 in this embodiment differs from a sine wave in that it has straight line portions between peaks and valleys, although the waveform of the reactant gas flow passage 21 may also be a sine wave.

[0038] The reaction gas flow paths 21 are arranged in parallel in a direction perpendicular to the meandering direction (the left-right direction in FIG. 2). Specifically, the reaction gas flow paths 21 are arranged in close proximity to each other in the up-down direction in FIG. 2 with the phases of the waveforms of the reaction gas flow paths 21 aligned. 3A, the cross-sectional shape of the reactant gas flow channel 21 is an isosceles trapezoid. Specifically, the cross-sectional shape of the reactant gas flow channel 21 is an isosceles trapezoid having a lower base that is longer than an upper base on the cathode 12a side.

[0039] As shown in Figures 2 and 3A, the reactant gas flow path 21 of such a cathode side separator 2 has a first reactant gas flow path 22 that supplies an oxygen-containing gas (reactant gas) to the cathode 12a that constitutes the power generation region A1, and a second reactant gas flow path 23 that is parallel to the first reactant gas flow path 22 so as to correspond to the non-power generation region A2.

[0040] As shown in Fig. 2, the first reactant gas flow path 22 is disposed so that at least a portion of the first reactant gas flow path 22 is in contact with the electrolyte membrane 11, whose upper edge position P1 is indicated by a hidden line (dotted line). Incidentally, as shown in Fig. 2, the power generating cell C is defined by the edge of the electrolyte membrane 11 as the boundary between the power generating region A1 and the non-power generating region A2.

[0041] The second reactant gas flow channel 23 is disposed so that at least a portion thereof contacts the cathode 12a, whose upper edge position P2 is indicated by a hidden line (dotted line) as shown in Fig. 2. Specifically, the second reactant gas flow channel 23 is disposed so that at least a portion thereof contacts a gas diffusion layer (not shown) of the cathode 12a (see Fig. 3A) that is layered on the proton non-conductive resin frame 13 (see Fig. 3A). As shown in FIG. 2, the second reactant gas flow path 23 is disposed between the first reactant gas flow path 22 and a seal portion 24, which will be described next, so as to be parallel to the first reactant gas flow path 22.

[0042] Fig. 5 is a plan view (rear view) of the cathode separator 2 shown in Fig. 1 as viewed from the membrane electrode assembly 1 side. Note that in Fig. 5, the reactant gas channels 21 arranged in parallel in the vertical direction on the rear surface of the cathode separator 2 are depicted in a simplified form for convenience of drawing. As shown in FIG. 5, the seal portion 24 of the cathode side separator 2 is formed so as to surround the plurality of reaction gas channels 21 arranged in parallel when viewed from the rear (plan view). In addition, the sealing portion 24 is formed in a ring shape so as to integrally surround the reactant gas supply port 10a, which supplies an oxygen-containing gas (oxidant gas) to the reactant gas flow path 21, the reactant gas exhaust port 10d, which exhausts the oxygen-containing gas (oxidant gas) from the reactant gas flow path 21, the inlet path 26 consisting of a groove that guides the oxygen-containing gas (oxidant gas) from the reactant gas supply port 10a to the reactant gas flow path 21, the exhaust path 27 consisting of a groove that guides the oxygen-containing gas (oxidant gas) from the reactant gas flow path 21 to the reactant gas exhaust port 10d, and the reactant gas exhaust port 10d and the reactant gas supply port 10e, which are used to supply and exhaust a hydrogen-containing gas (fuel gas) to the anode side separator 3 (see Figure 1).

[0043] 3A and 3B, this type of sealing portion 24 comes into contact with the resin frame 13 of the membrane electrode assembly 1 to prevent leakage of oxygen-containing gas (oxidizer gas) in the power generation cell C. Specifically, the bead-shaped sealing portion 24 elastically deforms due to the load applied when the cathode separator 2 is stacked as described above, and is pressed against the membrane electrode assembly 1, thereby exerting a sealing function for oxygen-containing gas (oxidizer gas). 5, reference numeral 4 denotes an opening seal that individually surrounds the periphery of the reaction gas supply port 10a and the reaction gas exhaust port 10d. The opening seal 4 is also provided in the communication hole 10 that supplies and exhausts the hydrogen-containing gas (fuel gas) to and from the anode-side separator 3 (see FIG. 1) and in the communication hole 10 that supplies and exhausts the cooling medium between the cathode-side separator 2 and the anode-side separator 3 (see FIG. 1).

[0044] Returning to FIG. 2, the seal portion 24 in this embodiment is formed in a wavy line shape with a constant wavelength and a constant amplitude in a portion adjacent to the reaction gas flow channel 21. Specifically, the seal portions 24 are formed on the outer sides of the second reactant gas channels 23 at both ends of the power generating cell C in the vertical width direction so as to be aligned with the second reactant gas channels 23 . That is, the power generation cell C of this embodiment is configured such that a second reactant gas flow path 23 is formed outside a plurality of first reactant gas flow paths 22 arranged in parallel to supply reactant gas to the power generation region A1, corresponding to the non-power generation region A2, and further has a seal portion 24 on the outside of the second reactant gas flow path 23 via a bypass flow path 25.

[0045] 2, the wavelength of the waveform of the seal portion 24 is half the wavelength of the waveform of the reactant gas flow path 21. The wavy convex portion 21a of the second reactant gas flow path 23 faces the wavy concave portion 24b of the seal portion 24 in the up-down direction. The wavy concave portion 21b of the second reactant gas flow path 23 faces the wavy concave portion 24b of the seal portion 24. As a result, the width of the bypass flow passage 25 at the portion where the recess 24b of the seal portion 24 and the protrusion 21a of the second reactant gas flow passage 23 face each other is narrower than the width of the bypass flow passage 25 at the portion where the recess 24b of the seal portion 24 and the recess 21b of the second reactant gas flow passage 23 face each other.

[0046] Fig. 6A is a partial enlarged view of a portion VIA in Fig. 5. Fig. 6B is a partial enlarged view of a portion VIB in Fig. 5. As shown in FIG. 6A, in the cathode side separator 2 of this embodiment, even in the upstream portion of the second reactant gas flow path 23, which is the reactant gas flow path 21 on the reactant gas supply port 10a side, i.e., the reactant gas flow path 21 closest to the seal portion 24, the convex portion 21a of the second reactant gas flow path 23 faces the concave portion 24b of the seal portion 24.

[0047] As shown in FIG. 6B, even in the upstream portion of the second reactant gas flow path 23, which is the reactant gas flow path 21 closest to the seal portion 24 on the lower end side of the cathode side separator 2, the convex portion 21a of the second reactant gas flow path 23 faces the concave portion 24b of the seal portion 24. In addition, in Fig. 6A and Fig. 6B, the symbol F indicates the flow of the reaction gas from the reaction gas supply port 10a (see Fig. 6A) through the introduction path 26 toward the reaction gas flow path 21 and the bypass flow path 25 by an arrow. The symbol P1 indicates the position of the outer periphery of the electrolyte membrane 11 (see Fig. 3A) indicated by a virtual line (two-dot chain line). The symbol P2 indicates the position of the outer periphery of the cathode 12a (see Fig. 3A) indicated by a virtual line (two-dot chain line). In Fig. 6A, the symbol 28 indicates a communication path that passes over the opening seal 4 and communicates the reaction gas supply port 10a with the introduction path 26. In Fig. 6B, the symbol 10 indicates a communication hole that supplies a hydrogen-containing gas (fuel gas) to the anode-side separator 3 (see Fig. 1).

[0048] FIG. 6C is a partially enlarged plan view that illustrates how the recess 24b of the seal portion 24 and the protrusion 21a of the reaction gas flow field 21 face each other. As shown in FIG. 6C, the apex 21a1 of the protrusion 21a of the reaction gas flow field 21 is located between the apexes 24a1 of two adjacent protrusions 24a of the seal portion 24. As shown in FIG. It is assumed that the apex 21a1 of the protrusion 21a in the reaction gas flow channel 21 is located on a straight line L connecting the apexes 24a1 of two adjacent protrusions 24a of the seal portion 24.

[0049] The convex portion 24a of the seal portion 24 and the convex portion 21a of the reactant gas flow passage 21 form a restricting portion that restricts the inflow of the reactant gas (oxygen-containing gas) in the bypass flow passage 25. That is, the restricting portion in this embodiment is configured as a narrow section that extends relatively long in the flow direction of the reactant gas. Specifically, the restricting portion is configured by bringing the inclined surfaces of the convex portion 24a and the convex portion 21a into close proximity to each other. The restricting portion formed so that the inclined surfaces of the convex portion 24a and the convex portion 21a are close to each other in this manner can ensure a longer restricting portion in the flow direction of the reactant gas compared to a restricting portion arranged so that the top 24a1 of the convex portion 24a and the top 21a1 of the convex portion 21a face each other.

[0050] 6C, the apex 21a1 of the protrusion 21a in the reactant gas flow passage 21 may be configured to protrude toward the seal portion 24 beyond the straight line L. This makes it possible to more effectively restrict the inflow of the reactant gas (oxygen-containing gas) into the bypass flow passage 25.

[0051] Next, the anode side separator 3 (see FIG. 1) will be described. As shown in FIG. 1, the anode side separator 3 has a reactant gas flow channel 31 on its surface facing the membrane electrode assembly 1, the reactant gas flow channel 31 corresponding to the reactant gas flow channel 21 of the cathode side separator 2 (see FIG. 5). In the anode-side separator 3, the hydrogen-containing gas (fuel gas) supplied from the reactant gas supply port 10eb to the inlet channel 36 flows through the reactant gas flow channel 31 and is discharged via the discharge channel 37 to the reactant gas discharge port 10b.

[0052] The reactant gas flow channel 31 extends from one end to the other end of the anode side separator 3, similar to the reactant gas flow channel 21 (see FIG. 5) of the cathode side separator 2. That is, the reactant gas flow channel 31 shown in FIG. 1 is formed in the shape of a wavy line with a constant wavelength and constant amplitude that meanders in one direction from left to right. The reaction gas flow channels 31 are arranged in parallel in a direction perpendicular to the meandering direction (the left-right direction in FIG. 1) so that the phases of the waveforms of the reaction gas flow channels 31 are aligned and adjacent to each other. As shown in FIGS. 3A and 3B, the cross-sectional shape of the reaction gas flow channel 31 is an isosceles trapezoid.

[0053] 3A and 3B, the reactant gas flow path 31 includes a first reactant gas flow path 32 that supplies a hydrogen-containing gas (reactant gas) to the anode 12b constituting the power generation region A1, and a second reactant gas flow path 33 that is parallel to the first reactant gas flow path 32 so as to correspond to the non-power generation region A2. The first reactant gas flow path 32 is disposed so that at least a portion of the first reactant gas flow path 32 is in contact with the electrolyte membrane 11. The separator portion that forms the second reactant gas flow path 33, together with the separator portion that forms the second reactant gas flow path 23 of the cathode-side separator 2, sandwiches the resin frame 13 with the cathode 12a and anode 12b between them.

[0054] 3A and 3B, it is assumed that the reactant gas flow channel 31 of the anode-side separator 3 has a larger flow channel cross-sectional area and a longer pitch than the reactant gas flow channel 21 of the cathode-side separator 2. Although not shown, the wavelength of the waveform in the reactant gas flow channel 31 of the anode-side separator 3 is set to be the same as the wavelength of the reactant gas flow channel 21 of the cathode-side separator 2, but is not limited to this. Incidentally, when the reactant gas flow channel 31 and the reactant gas flow channel 21 are set to have the same wavelength, it is preferable that they are arranged so that their phases are shifted from each other.

[0055] In Fig. 1, reference numeral 34 denotes a seal portion of the anode-side separator 3. This seal portion 34 is formed in an annular shape in the front view (plan view) shown in Fig. 1, similar to the seal portion 24 (see Fig. 5) of the cathode-side separator 2. That is, the seal portion 34 is formed so as to integrally surround the reactant gas flow path 31, the reactant gas supply port 10e, the reactant gas discharge port 10b, the introduction path 36, the discharge path 37, and the reactant gas supply port 10a and the reactant gas discharge port 10d that are used for supplying and discharging an oxygen-containing gas (oxidant gas) to and from the cathode-side separator 2 (see Fig. 1). 3A and 3B, this type of seal portion 34 comes into contact with the resin frame portion 13 of the membrane electrode assembly 1 to prevent leakage of hydrogen-containing gas (fuel gas) in the power generation cell C. Specifically, the bead-shaped seal portion 34 elastically deforms due to the load applied when the anode separator 3 is stacked as described above, and is pressed against the membrane electrode assembly 1, thereby exerting a sealing function for preventing leakage of hydrogen-containing gas (fuel gas).

[0056] As shown in FIG. 1, the seal portion 34 in this embodiment is formed in a wavy line shape with a constant wavelength and a constant amplitude in a portion adjacent to the reaction gas flow channel 31. As shown in FIGS. 3A and 3B, the seal portion 34 is formed on the outer side of the second reactant gas flow channel 33 in the vertical width direction of the power generating cell C so as to be aligned with the second reactant gas flow channel 33. That is, the anode side separator 3 in this embodiment is configured so that a second reactant gas flow path 33 is formed outside a plurality of first reactant gas flow paths 32 arranged in parallel to supply reactant gas to the power generation region A1, so as to correspond to the non-power generation region A2, and further has a seal portion 34 on the outside of the second reactant gas flow path 33 via a bypass flow path 35.

[0057] Although not shown in the drawings, the wavelength of the waveform of the seal portion 34 is assumed to be half the wavelength of the waveform of the reactant gas flow passage 31, similar to the relationship between the seal portion 24 (FIG. 6C) of the cathode-side separator 2 and the reactant gas flow passage 21 (FIG. 6C). As also shown in FIG. 6C, the apex 31a1 of the protrusion 31a in the reactant gas flow passage 31 is assumed to be located on a straight line L connecting the apex 34a1 of two adjacent protrusions 34a of the seal portion 34, or to protrude beyond the straight line L toward the seal portion 34. The protrusion 31a of the reactant gas flow passage 31 and the protrusion 34a of the seal portion 34 form a restricting portion that restricts the inflow of the reactant gas (hydrogen-containing gas) into the bypass flow passage 35. 1, reference numeral 4 denotes an opening seal that individually surrounds the periphery of the reaction gas exhaust port 10b and the reaction gas exhaust port 10d. The opening seal 4 is also provided in the communication hole 10 for supplying and discharging the oxygen-containing gas (oxidizer gas) and the communication hole 10 for supplying and discharging the cooling medium.

[0058] <Action and effect> Next, the effects of the power generating cell C according to this embodiment will be described. A conventional power generating cell (see, for example, Patent Document 1) has a restricting member that blocks the bypass flow of reactant gas. While such a limiting member increases the reaction rate of the reactant gas in the power generation region, it may cause variations in the surface pressure due to the deflection of the separator. That is, in a power generation cell having a conventional limiting member (see, for example, Patent Document 1), there is a trade-off between improving the reaction rate of the reactant gas and suppressing the variation in the surface pressure of the separator. This tendency is particularly noticeable in a power generation cell in which the limiting member is constituted by a rib extending in a direction intersecting the extension direction of the reactant gas flow path.

[0059] In contrast, in the cathode side separator 2 of the power generation cell C of this embodiment, the apex 21a1 of the convex portion 21a of the reactant gas flow path 21 is located on the straight line L connecting the apexes 24a1 of two adjacent convex portions 24a of the seal portion 24, or protrudes beyond the straight line L toward the seal portion 24. In addition, the bypass flow path 25 of the power generation cell C forms a restriction portion that restricts the inflow of the reactant gas in a narrow section that extends relatively long in the flow direction of the reactant gas, by the recess 24b of the seal portion 24 and the protrusion 21a of the reactant gas flow path 21 facing it.

[0060] In the power generating cell C having such a cathode separator 2, the flow rate of the reactant gas that tries to bypass the power generating region A1 is reduced by the restricting portion formed by the convex portion 24a of the seal portion 24 and the convex portion 21a of the reactant gas flow channel 21 (second reactant gas flow channel 23). This enables the power generating cell C to increase the reaction rate of the reactant gas in the power generating region A1.

[0061] Furthermore, in the power generating cell C of this embodiment, when the power generating cells C are stacked under a predetermined load, even if the cathode side separator 2 is deflected, the deflection is eliminated while allowing the cathode side separator 2 to extend in the parallel direction of the reactant gas flow paths 21 at the portion corresponding to the bypass flow path 25. This makes it possible for the power generating cell C to more reliably prevent the occurrence of variations in the surface pressure of the cathode side separator 2.

[0062] In the anode-side separator 3 of the power generation cell C of this embodiment, too, it is assumed that the apex 31a1 of the convex portion 31a of the reactant gas flow path 31 is located on the straight line L connecting the apexes 34a1 of two adjacent convex portions 34a of the seal portion 34, or protrudes beyond the straight line L toward the seal portion 24. That is, the power generating cell C can prevent leakage of the reactant gas from the reactant gas flow paths 21, 31 and the seal portions 24, 34 more effectively than in the past.

[0063] In addition, in the power generation cell C of this embodiment, even in the reactant gas flow passages 21, 31 on the reactant gas supply port 10a, 10e side, i.e., the upstream portion of the reactant gas flow passage 21, 31 closest to the seal portion 24, 34, the convex portion 21a of the reactant gas flow passage 21, 31 faces the concave portion 24b of the seal portion 24, 34. Such a power generating cell C can more reliably reduce the flow rate of the reactant gas that tries to bypass the power generating region A1. The power generating cell C can further increase the reaction rate of the reactant gas in the power generating region A1.

[0064] The cathode separator 2 of the power generating cell C of this embodiment includes a plurality of first reactant gas channels 22 arranged in parallel to supply reactant gas to the power generating region A1, and a second reactant gas channel 23 provided between the seal portion 24 and the first reactant gas channel 22 to correspond to the non-power generating region A2. The first reactant gas channels 22 and the second reactant gas channel 23 are formed such that the phases of the respective wavy lines match each other. The anode-side separator 3 also includes a plurality of first reactant gas channels 32 arranged in parallel to supply reactant gas to the power generation region A1, and a second reactant gas channel 33 provided between the seal portion 34 and the first reactant gas channel 32 to correspond to the non-power generation region A2. The power generation cell C is assumed to have the first reactant gas channels 32 and the second reactant gas channel 33 formed such that the phases of the respective wavy lines match each other.

[0065] In such a power generating cell C, when the power generating cells C are stacked, the formation portions of the reactant gas channels 21, 31 tend to extend to the portions corresponding to the bypass channels 25, 35 in order to eliminate the bending. At this time, since the reactant gas channels 21, 31 are made up of a plurality of first reactant gas channels 22, 32 and second reactant gas channels 23, 33 arranged in parallel and the phases of the respective wavy lines match each other, the formation portions of the reactant gas channels 21, 31 spread uniformly in the direction along the respective faces of the cathode side separator 2 and the anode side separator 3. Therefore, the occurrence of variations in the surface pressure on the cathode side separator 2 and the anode side separator 3 is more reliably prevented.

[0066] In the cathode separator 2 of the power generating cell C of this embodiment, the second reactant gas flow field 23 contacts the gas diffusion layer of the cathode 12a that extends to the non-power generating region A2. In such a power generating cell C, water produced at the cathode 12a in the power generating region A1 partially moves to the gas diffusion layer of the cathode 12a in the non-power generating region A2 due to capillary action. The produced water that has migrated to the cathode 12a in the non-power generation region A2 is discharged together with the reactant gas (oxygen-containing gas) flowing through the second reactant gas flow channel . In such a power generating cell C, the water produced in the cathode 12a is discharged together with the reactant gas from both the first reactant gas flow path 22 and the second reactant gas flow path 23. Flooding of the cathode 12a by water produced during power generation is more reliably prevented.

[0067] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be embodied in various forms. Fig. 7 is a partially enlarged plan view of the cathode separator 2 in a power generating cell C according to another embodiment, and corresponds to Fig. 6A in the above embodiment. In Fig. 7, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The cathode side separator 2 of the power generating cell C shown in Figure 7 differs from the cathode side separator 2 shown in Figure 6A in that the apex 21a1 of the convex portion 21a of the reactant gas flow path 21 and the apex 24a1 of the convex portion 24a of the seal portion 24 are formed in an opposing position.

[0068] Furthermore, even in the reactive gas flow passage 21 on the reactive gas supply port 10a side, i.e., the upstream portion of the reactive gas flow passage 21 closest to the seal portion 24, the apex 21a1 of the convex portion 21a of the reactive gas flow passage 21 and the apex 24a1 of the convex portion 24a of the seal portion 24 are formed in opposing positions. In the power generating cell C, the protrusion 24a of the seal portion 24 and the protrusion 21a of the reactant gas flow passage 21 form a restricting portion that restricts the inflow of the reactant gas in the bypass flow passage 25. Moreover, this configuration is not limited to the cathode side separator 2, but can also be applied to the anode side separator 3. Such a power generating cell C makes it easy to set the distance (alignment) between the protrusions 24a, 34a of the seal portions 24, 34 and the protrusions 21a, 31a of the reactant gas flow paths 21, 31, improving the freedom in designing the restriction portion.

[0069] In addition, in the above embodiment, the wavelength of the waveform of the seal portion 24, 34 is set to half the wavelength of the waveform of the reaction gas flow path 21, 31, but this is not limited to this and can be set appropriately so as to provide a reaction gas regulating portion between the convex portion 24a, 34a of the seal portion 24, 34 and the convex portion 21a, 31a of the reaction gas flow path 21, 31. In addition, the seal portions 24, 34 in the above embodiment utilize the beads of the cathode side separator 2 and the anode side separator 3, but may instead be seals made of an elastic material provided in a wavy line shape. The seals may also be configured such that an elastic material is provided on the top surface of each bead of the cathode side separator 2 and the anode side separator 3. [Explanation of symbols]

[0070] 1 Electrolyte membrane / electrode structure 2 Cathode side separator 3 Anode side separator 10a Reactive gas supply port 10e Reactive gas supply port 12a Cathode 12b Anode 13 Resin frame 21 Reaction gas flow path 21a: Protruding portion of reaction gas flow passage 21a1 Top of the protruding portion of the reaction gas flow path 21b Recess of reaction gas passage 22 First reactant gas flow path 23 Second reactant gas flow path 24 Seal part 24a Two adjacent protrusions of the seal 24a1 The tops of two adjacent protrusions of the seal 24b Sealing recess 25 Bypass flow path 31 Reaction gas flow path 32 first reaction gas flow path 33 Second reaction gas flow path 34 Seal part 35 Bypass flow path A1 Power Generation Area A2 Non-power generation area C Power generation cell L straight line

Claims

1. an electrolyte membrane electrode assembly having electrodes provided on both sides of an electrolyte membrane; a resin frame provided on an outer periphery of the membrane electrode assembly; Separators disposed on both sides of the membrane electrode assembly; A power generating cell comprising: the separator is a plate-like component made of metal, and is provided with a wavy-line-shaped reactant gas flow path through which a reactant gas flows along the membrane electrode assembly from one end to the other end of the separator, and a seal portion that is in contact with the resin frame and surrounds the reactant gas flow path to prevent leakage of the reactant gas, a sealing portion having a plurality of apexes that are convex toward the reactant gas flow path, and the apexes that are convex toward the sealing portion side of the reactant gas flow path are located on a straight line connecting two adjacent apexes of the sealing portion or protrude beyond the straight line toward the sealing portion.

2. the separator is provided with a reactant gas supply port for supplying a reactant gas to the reactant gas flow channel, an apex portion of the reaction gas flow passage on the reaction gas supply port side that is convex toward the seal portion is located between two adjacent apexes of the seal portion, 2. The power generation cell according to claim 1, characterized in that a restricting portion that restricts the flow of reactant gas between the reactant gas flow passage and the seal portion is formed by a convex portion of the seal portion that forms an apex and a convex portion of the reactant gas flow passage that forms an apex.

3. an electrolyte membrane electrode assembly having electrodes provided on both sides of an electrolyte membrane; a resin frame provided on an outer periphery of the membrane electrode assembly; Separators disposed on both sides of the membrane electrode assembly; A power generating cell comprising: the separator is a plate-like component made of metal, and is provided with a wavy-line-shaped reactant gas flow path through which a reactant gas flows along the membrane electrode assembly from one end to the other end of the separator, and a seal portion that is in contact with the resin frame and surrounds the reactant gas flow path to prevent leakage of the reactant gas, a sealing portion having an apex that is convex toward the reactant gas flow path side, and the apex that is convex toward the sealing portion side of the reactant gas flow path is formed at a position opposite to the apex of the sealing portion that is convex toward the reactant gas flow path side.

4. the separator is provided with a reactant gas supply port for supplying a reactant gas to the reactant gas flow channel, an apex portion that is convex toward the seal portion in the reaction gas flow path on the reaction gas supply port side is provided at a position opposite to the apex of the seal portion, 4. The power generation cell according to claim 3, characterized in that a restricting portion that restricts the flow of reactant gas between the reactant gas flow passage and the seal portion is formed by a convex portion of the seal portion that forms an apex and a convex portion of the reactant gas flow passage that forms an apex.

5. The reaction gas flow path is a plurality of first reactant gas flow paths arranged in parallel to supply reactant gas to a power generation region of the membrane electrode assembly; a second reactant gas flow channel disposed between the seal portion and the first reactant gas flow channel in parallel with the first reactant gas flow channel so as to correspond to a non-power generation region of the membrane electrode assembly; Equipped with 4. The power generating cell according to claim 1, wherein the first reactant gas flow passages and the second reactant gas flow passages are formed such that the phases of the wavy lines of the first reactant gas flow passages and the second reactant gas flow passages match each other.

6. an outer periphery of the membrane electrode assembly has a non-power generation region in which the electrodes are partially overlapped with the resin frame; 6. The power generating cell according to claim 5, wherein the second reactant gas flow channel is in contact with a gas diffusion layer of the electrode.

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