JP2009199882A - Fuel cell, and fuel cell stack equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell efficiently using reaction gas for well improving power generating performance while preventing the deterioration of the peripheral edge of a polymer electrolyte membrane. <P>SOLUTION: The fuel cell includes an electrolyte layer-electrode assembly 5 with an electrolyte layer 1 and a pair of electrodes 4a, 4b clamping a portion inward of the peripheral edge of the electrolyte layer 1, a pair of annular gaskets 6a, 6b arranged to encircle the electrodes 4a, 4b of the electrolyte layer-electrode assembly 5, and a pair of conductive separators 7a, 7b plate-shaped and arranged to clamp the electrolyte layer-electrode assembly 5 and the gaskets 6a, 6b, and having trench-shaped reaction gas flow paths 8, 9 formed on one main face abutting on the electrodes 4a, 4b where the reaction gas flows. In at least one of the pair of gaskets 6a, 6b, a gasket flow path 31 is provided which is communicated with the reaction gas flow paths 8, 9 so that the reaction gas flows in the peripheral edge of the electrolyte layer 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell and a fuel cell stack including the same, and more particularly to a structure of a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell (hereinafter referred to as PEFC) generates electricity and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. . A single cell (cell) of PEFC is composed of a polymer electrolyte membrane and a pair of gas diffusion electrodes (anode and cathode), MEA (Membrane-Electrode-Assembly: electrolyte layer-electrode laminate), gasket, and conductivity. And a separator.

  In the MEA, from the viewpoint of disposing a gasket to prevent gas leakage, the size of the main surface of the polymer electrolyte membrane is larger than the size of the main surface of the gas diffusion electrode, and the polymer is viewed from the front. The periphery of the electrolyte membrane is configured to protrude outward from the outer periphery of the gas diffusion electrode. Further, the separator is provided with a groove-like reaction gas flow path for flowing a fuel gas or an oxidant gas (these are called reaction gases) on the main surface in contact with the gas diffusion electrode.

  The MEA in which a gasket is disposed on the peripheral edge of the polymer electrolyte membrane is sandwiched between a pair of separators to form a cell. A fuel cell stack is formed by stacking a plurality of cells, sandwiching both ends of the stacked cells with end plates, and fastening the end plates and cells with fasteners.

  From the viewpoint of preventing leakage of reaction gas and the like in such PEFC, a solid polymer electrolyte fuel cell stack in which a flow groove through which an inert gas or water flows is provided in the peripheral portion of a gas separator (separator) is known. (For example, refer to Patent Document 1). FIG. 15 is a cross-sectional view schematically showing a schematic configuration of the solid polymer electrolyte fuel cell stack disclosed in Patent Document 1. As shown in FIG.

As shown in FIG. 15, in the fuel cell stack 200 disclosed in Patent Document 1, the gas seal packing (gasket) 201 is provided with a communication hole 203 communicating with the flow groove 202. Accordingly, it is described that an inert gas or water can be introduced into the circulation groove 202.
JP-A-6-260193

  By the way, when power generation of the fuel cell is performed, electricity and moisture are generated by the reaction of the reaction gas. The generated water accompanying the reaction of the reaction gas is generated at the cathode, and a part of the generated water moves to the anode side (so-called reverse diffusion). These produced waters are supplied to the reaction gas channel. The reaction gas flowing through the reaction gas channel is humidified. Thereby, moisture is supplied to the polymer electrolyte membrane.

  However, since the reaction gas is not supplied at the peripheral portion of the polymer electrolyte membrane that is not covered with the gas diffusion electrode, the supply of moisture to the polymer electrolyte membrane is not sufficient. Deterioration may be accelerated.

  The present invention has been made in view of the above-described problems of the prior art, and it is possible to efficiently improve the power generation performance by efficiently using a reaction gas and suppressing deterioration of the peripheral portion of the polymer electrolyte membrane. An object of the present invention is to provide a fuel cell and a fuel cell stack.

  As a result of intensive studies in order to solve the above-described problems of the prior art, the present inventors have provided a gasket channel through which a reaction gas flows in a gasket disposed at the peripheral portion of the polymer electrolyte membrane, The present inventors have found that supplying water to the peripheral portion of the polymer electrolyte membrane is extremely effective in achieving the object of the present invention, and have conceived the present invention.

  That is, the fuel cell according to the present invention comprises an electrolyte layer and an electrolyte layer-electrode assembly having a pair of electrodes sandwiching an inner portion from the periphery of the electrolyte layer, and the electrolyte of the electrolyte layer-electrode assembly. A pair of annular gaskets arranged so as to sandwich the peripheral edge and surround each of the pair of electrodes, and plate-shaped, arranged so as to sandwich the electrolyte layer-electrode assembly and the pair of gaskets. And a pair of conductive separators each having a groove-like reaction gas flow channel in which a reaction gas flows on one main surface in contact with the electrode, and at least one of the pair of gaskets, A gasket channel is provided that communicates with the reaction gas channel and is configured to allow the reaction gas to flow while contacting the peripheral edge of the electrolyte layer.

  As described above, moisture (water vapor) generated by the reaction of the reaction gas is supplied to the reaction gas channel. For this reason, the reaction gas channel contains a reaction gas sufficiently containing water vapor. In the fuel cell according to the present invention, the reaction gas having sufficient water vapor is caused to flow through the gasket flow path formed in the gasket disposed at the peripheral portion of the electrolyte layer. Since the peripheral portion of the fuel cell is close to the atmosphere, the temperature is lower than that of the central portion, so that the water vapor contained in the reaction gas flowing through the gasket channel is condensed, and the condensed water is used as the electrolyte layer. By supplying, drying of the peripheral part of an electrolyte layer can be suppressed.

  In addition, contacting with the peripheral part of an electrolyte layer means the state which the peripheral part of an electrolyte layer is exposed to the gasket flow path.

  In the fuel cell according to the present invention, the gasket channel may be formed along the outer periphery of the electrode.

  In the fuel cell according to the present invention, the gasket channel may be formed so as to surround the outer periphery of the electrode.

  In the fuel cell according to the present invention, the gasket channel may be in communication with a portion of the reaction gas channel that is downstream of a portion that contacts the electrode.

  In addition, the part which contacts the electrode of a reactive gas flow path means the part which the electrode is exposed to the reactive gas flow path (facing).

  Further, in the fuel cell according to the present invention, a groove-like cooling medium flow path through which a cooling medium flows is formed on the other main surface of the separator that contacts the gasket provided with the gasket flow path, At least a part of the upstream portion of the cooling medium flow path may be provided at the peripheral edge of the separator.

  Thereby, the peripheral part of the separator which contacts the gasket provided with the gasket flow path is cooled by the cooling medium having a low temperature flowing through the upstream part of the cooling medium flow path. Then, the gasket that contacts the cooled separator is cooled. For this reason, water vapor contained in the reaction gas flowing through the gasket channel can be easily condensed, and drying of the peripheral edge of the electrolyte layer can be more easily suppressed.

  Here, the upstream portion of the cooling medium flow path is between the cooling medium flow paths when one end is the upstream end of the cooling medium flow path and the other end is a portion satisfying the formula: L1 ≦ L2. Say part. In the above formula, L1 indicates the flow path length upstream of the cooling medium flow path, and L2 indicates the total flow path length of the cooling medium flow path.

  Further, in the fuel cell according to the present invention, the portion of the reaction gas flow path provided in the separator that contacts the gasket provided with the gasket flow path has a serpentine shape formed in a serpentine shape. You may be comprised from the flow path and the peripheral flow path formed so that the peripheral part of the said electrode might be followed.

  As a result, the reaction gas containing water sufficiently flows through the peripheral flow path and the gasket flow path, thereby supplying the water from both the inside and outside of the outer periphery of the electrode to the peripheral edge of the electrolyte layer. And deterioration due to drying of the periphery of the electrolyte layer can be more effectively suppressed.

  In the fuel cell according to the present invention, the reaction gas flow path provided in the separator abutting on the gasket provided with the gasket flow path is a first reaction in which the reaction gas flows while being in contact with the electrode. You may be comprised from the gas flow path and the 2nd reaction gas flow path formed so that it might join with the said gasket flow path in the thickness direction of the said separator.

  In the fuel cell according to the present invention, a plurality of the reaction gas flow paths are disposed on one main surface of the separator, and a portion (hereinafter referred to as the electrode) of the plurality of reaction gas flow paths is in contact with the electrodes. , The electrode contact portion) is formed so as to run in parallel, and the downstream portion of the electrode contact portion of the pair of reaction gas channels located on the outermost side among the plurality of reaction gas channels is on the outer periphery of the electrode It may be formed along.

  As a result, the gasket flow paths are not communicated with all the reaction gas flow paths, so that an increase in the overall pressure loss of the plurality of reaction gas flow paths can be mitigated.

  Further, in the fuel cell according to the present invention, the downstream portion of the electrode contact portion of the pair of reaction gas channels located on the outermost side among the plurality of reaction gas channels is formed so as to surround the outer periphery of the electrode. May be.

  Further, in the fuel cell according to the present invention, an annular subgasket is provided between the electrolyte layer-electrode assembly and the gasket, and the gasket flow in the thickness direction of the separator. A sub-gasket channel may be provided so as to be joined to the path.

  Furthermore, in the fuel cell according to the present invention, a portion other than the upstream portion of the cooling fluid channel may be formed in a serpentine shape.

  The fuel cell stack according to the present invention is fastened by stacking a plurality of the fuel cells.

  The “reactive gas” in this specification includes not only the fuel gas and oxidant gas, but also the case where the fuel gas and oxidant gas contain products and unreacted substances generated by the electrode reaction.

  According to the fuel cell and the fuel cell stack of the present invention, the reaction gas containing more water is caused to flow through the gasket channel by power generation, the water vapor contained in the reaction gas is condensed, and supplied to the peripheral portion of the electrolyte layer. As a result, deterioration due to drying of the peripheral portion of the electrolyte layer can be suppressed, and power generation performance can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
[Configuration of fuel cell stack]
FIG. 1 is a cross-sectional view schematically showing a schematic configuration of the fuel cell stack according to Embodiment 1 of the present invention. In FIG. 1, a part is omitted.

  As shown in FIG. 1, the fuel cell stack 100 according to Embodiment 1 of the present invention includes a plurality of fuel cells (single cells) 11. Here, the fuel cell 11 is composed of a polymer electrolyte fuel cell.

  The fuel cell 11 includes an MEA (Membrane-Electrode-Assembly: electrolyte layer-electrode assembly) 5, an anode gasket 6a, a cathode gasket 6b, an anode separator 7a, and a cathode separator 7b.

  First, the configuration of the MEA 5 will be described.

  The MEA 5 includes a polymer electrolyte membrane (electrolyte layer) 1, an anode 4a, and a cathode 4b. The polymer electrolyte membrane 1 has a substantially quadrangular (here, rectangular) shape. On both surfaces of the polymer electrolyte membrane 1, an anode 4a and a cathode 4b (referred to as electrodes) are disposed so as to be located inward from the peripheral edge thereof. In the peripheral edge of the polymer electrolyte membrane 1, manifold holes such as a fuel gas supply manifold hole, which will be described later, are provided so as to penetrate in the thickness direction (not shown).

  The anode 4a is provided on one main surface of the polymer electrolyte membrane 1, and has an anode catalyst layer 2a and an anode gas diffusion layer 3a provided on the main surface of the anode catalyst layer 2a. Here, the anode catalyst layer 2a and the anode gas diffusion layer 3a are formed in a rectangular shape similar to the polymer electrolyte membrane 1, and when viewed from the thickness direction of the polymer electrolyte membrane 1, the anode gas diffusion layer 3a is the anode. The main surface is configured to be larger than the catalyst layer 2a.

  The cathode 4b is provided on the other main surface of the polymer electrolyte membrane 1, and has a cathode catalyst layer 2b and a cathode gas diffusion layer 3b provided on the main surface of the cathode catalyst layer 2b. Here, the cathode catalyst layer 2 b and the cathode gas diffusion layer 3 b are formed in a rectangular shape similar to the polymer electrolyte membrane 1, and the cathode gas diffusion layer 3 b is the cathode in the thickness direction of the polymer electrolyte membrane 1. The main surface is configured to be larger than the catalyst layer 2b.

  Next, each component of the MEA 5 will be described.

  The polymer electrolyte membrane 1 is made of a solid electrolyte and has hydrogen ion conductivity for selectively transporting hydrogen ions. In the MEA 5 during power generation, hydrogen ions generated at the anode 4a move through the polymer electrolyte membrane 1 toward the cathode 4b.

  The polymer electrolyte membrane 1 is not particularly limited, and a polymer electrolyte membrane mounted on a normal solid polymer fuel cell can be used. For example, a polymer electrolyte membrane made of perfluorocarbon sulfonic acid (for example, Nafion (trade name) manufactured by DuPont, USA, Flemion (trade name) and Aciplex (trade name) manufactured by Asahi Glass Co., Ltd., or Japan Gore-Tex (stock) GSII (trade name), etc.) manufactured by

  Preferred examples of the cation exchange group of the polymer electrolyte membrane 1 include those having a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, or a sulfonimide group. From the viewpoint of proton conductivity, the polymer electrolyte membrane 1 preferably has a sulfonic acid group.

  The resin constituting the polymer electrolyte membrane having a sulfonic acid group is preferably a dry resin having an ion exchange capacity of 0.5 to 1.5 meq / g. It is preferable that the ion exchange capacity of the polymer electrolyte membrane be 0.5 meq / g or more of a dry resin because the increase in the resistance value of the polymer electrolyte membrane during power generation can be more sufficiently reduced, and the ion exchange capacity is 1.5 meq. / G dry resin or less is preferred because it is easy to sufficiently ensure good gas diffusion characteristics in the catalyst layer while keeping the moisture content of the polymer electrolyte membrane appropriately. From the same viewpoint as described above, a dry resin having an ion exchange capacity of 0.8 to 1.2 meq / g is particularly preferable.

As the polymer _{electrolyte, CF 2 = CF- (OCF 2} CFX) m -O p - (CF 2) a perfluorovinyl compound represented by _n -SO ₃ H (m is an integer of 0 to 3, n Represents an integer of 1 to 12, p represents 0 or 1, and X represents a fluorine atom or a trifluoromethyl group.) And a copolymer comprising a polymer unit based on tetrafluoroethylene. Preferably there is.

Preferable examples of the fluorovinyl compound include compounds represented by the following formulas (1) to (3). However, in the following formula, q is an integer of 1 to 8, r is an integer of 1 to 8, and t is 1 to 8.
An integer of 3 is shown.

_{CF 2 = CFO (CF 2)} q -SO 3 H ··· (1)
_{CF 2 = CFOCF 2 CF (CF} 3) O (CF 2) r -SO 3 H ··· (2)
_{CF 2 = CF (OCF 2 CF} (CF 3)) t O (CF 2) 2 -SO 3 H ··· (3)
In addition, the polymer electrolyte membrane 1 may be comprised with 1 type or multiple types of polymer electrolyte.

  In addition, the polymer electrolyte membrane 1 may include a reinforcing body (filler) disposed in a state in which hydrogen ion conduction can be ensured from the viewpoint of ensuring sufficient mechanical strength. Examples of such a reinforcing body include a porous body having pores which can be filled with a polymer electrolyte (having hydrogen ion conductivity) or a fibrillar fiber. Moreover, as a material which comprises the said reinforcement body, polytetrafluoroethylene or polyfluoroalkoxyethylene is mentioned, for example.

  Fibril-like fibers are fibers in which fibrils (small fibers) existing on the surface are fluffed and fluffed (fibrillated), and fine air grooves (holes) between the fibrils. Refers to the fiber in which is formed. For example, all cellulosic fibers are bundles of many fibrils, and there are fine air grooves (holes) between the fibrils.

  The anode catalyst layer 2a and the cathode catalyst layer 2b are not particularly limited as long as the effects of the present invention can be obtained, and may have the same configuration as the catalyst layer of the gas diffusion electrode in a known fuel cell. For example, the structure may include a conductive carbon particle (powder) on which an electrode catalyst is supported and a polymer electrolyte having cation (hydrogen ion) conductivity. The structure which further contains water-repellent materials, such as ethylene, may be sufficient. The configurations of the anode catalyst layer 2a and the cathode catalyst layer 2b may be the same or different. In addition, as a polymer electrolyte, the same kind as the material which comprises the polymer electrolyte membrane 1 mentioned above may be used, and a different kind may be used.

  Moreover, metal particles can be used as the electrode catalyst constituting the anode catalyst layer 2a and the cathode catalyst layer 2b. The metal particles are not particularly limited, and various metals can be used. From the viewpoint of electrode reaction activity, platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, chromium, iron, titanium It is preferably at least one metal selected from the metal group consisting of manganese, cobalt, nickel, molybdenum, tungsten, aluminum, silicon, zinc, and tin. Among these, platinum or an alloy of platinum and at least one metal selected from the above metal group is preferable, and an alloy of platinum and ruthenium has a stable catalyst activity in the anode catalyst layer 2a, and is good for carbon monoxide. It is particularly preferable because it has excellent durability.

  Moreover, it is preferable that the said metal particle used for an electrode catalyst is 1-5 nm in average particle diameter. An electrode catalyst having an average particle diameter of 1 nm or more is preferable because it can be easily prepared industrially, and if it is 5 nm or less, the activity per mass of the electrode catalyst can be more easily secured, thereby reducing the cost of the fuel cell. Connection is preferable.

The conductive carbon particles preferably have a specific surface area of 50 to 1500 m ² / g. A specific surface area of 50 m ² / g or more is preferable because it is easy to increase the loading ratio of the electrode catalyst, and the output characteristics of the obtained anode catalyst layer 2a or cathode catalyst layer 2b can be more sufficiently secured. When the specific surface area is 1500 m ² / g or less, sufficiently large pores can be secured more easily and coating with a polymer electrolyte becomes easier, and the anode catalyst layer 2a or the cathode catalyst layer This is preferable because the output characteristics of 2b can be more sufficiently secured. From the same viewpoint as described above, the specific surface area is more preferably 200 to 900 m ² / g.

  The conductive carbon particles preferably have an average particle size of 0.1 to 1.0 μm. When the average particle diameter of the conductive carbon particles is 0.1 μm or more, gas diffusibility in the anode catalyst layer 2a or the cathode catalyst layer 2b is more easily secured, and flooding can be more reliably suppressed. Therefore, it is preferable. In addition, when the average particle diameter of the conductive carbon particles is 1.0 μm or less, it becomes easy to easily make the electrode catalyst covered with the polymer electrolyte in a good state, and the electrode catalyst covered area with the polymer electrolyte is more increased. Since it becomes easy to ensure enough, it becomes easy to ensure sufficient electrode performance more and is preferable.

  In addition, the anode catalyst layer 2a and the cathode catalyst layer 2b are used in this field by using a catalyst layer forming ink containing conductive carbon particles carrying an electrode catalyst made of a noble metal, a polymer electrolyte, and a dispersion medium. It can be formed by a known method.

  Moreover, as a material which comprises the anode gas diffusion layer 3a and the cathode gas diffusion layer 3b, what is known in the said field | area can be used, without being specifically limited. For example, in order to give gas permeability, a conductive base material having a porous structure made using carbon fine powder having a high specific surface area, a pore former, carbon paper, carbon cloth or the like may be used. Good. Further, from the viewpoint of obtaining sufficient drainage, a water-repellent polymer such as a fluororesin may be dispersed in the anode gas diffusion layer 3a or the cathode gas diffusion layer 3b. Furthermore, from the viewpoint of obtaining sufficient electron conductivity, the anode gas diffusion layer 3a or the cathode gas diffusion layer 3b may be made of an electron conductive material such as carbon fiber, metal fiber, or carbon fine powder. The configurations of the anode gas diffusion layer 3a and the cathode gas diffusion layer 3b may be the same or different.

  Next, the remaining configuration of the fuel cell 11 will be described.

  Around the periphery of the anode 4a and the cathode 4b of the MEA 5, a pair of gaskets having a substantially rectangular cross section and an annular gasket, that is, an anode gasket 6a and a cathode gasket 6b, are disposed with the peripheral edge of the polymer electrolyte membrane 1 interposed therebetween. . Further, a through groove 31 that penetrates in the thickness direction is formed in the cathode gasket 6 b, and the through groove 31 constitutes the gasket channel 31. As will be described later, manifold holes such as a fuel gas supply manifold hole are provided in the peripheral portions of the anode gasket 6a and the cathode gasket 6b (see FIG. 4). This prevents the fuel gas, air, and oxidant gas from leaking out of the battery, and prevents these gases from being mixed with each other in the fuel cell 11.

  The constituent materials of the anode gasket 6a and the cathode gasket 6b are not particularly limited as long as they have excellent gas sealing properties, and those used for gaskets of known polymer electrolyte fuel cells are used. can do. For example, the anode gasket 6a and the cathode gasket 6b are conventionally known methods using O-rings, rubber-like sheets (sheets made of fluororubber, etc.), composite sheets of elastic resin and rigid resin, fluorine-based synthetic resin sheets, and the like. Can be produced.

  Further, a plate-like anode separator 7a and a cathode separator 7b having conductivity are disposed so as to sandwich the MEA 5, the anode gasket 6a, and the cathode gasket 6b. Further, as will be described later, manifold holes such as a fuel gas supply manifold hole 23 are provided in the peripheral portions of the separators 7a and 7b (see FIGS. 2 and 3).

  Thus, the MEA 5 is mechanically fixed, and when the plurality of fuel cells 11 are stacked in the thickness direction, the MEA 5 is electrically connected. In addition, these separators 7a and 7b can use the metal excellent in heat conductivity and electroconductivity, graphite, or what mixed graphite and resin, for example, carbon powder and a binder (solvent). A mixture prepared by injection molding or a plate of titanium or stainless steel plated with gold can be used.

  A fuel gas is supplied to the anode 4a on one main surface (hereinafter referred to as an inner surface) of the anode separator 7a that is in contact with the anode 4a, and a product (for example, moisture) or an unreacted fuel gas generated by the electrode reaction is supplied to the anode 4a. A groove-like fuel gas flow path 8 for carrying away to the outside of the MEA 5 is provided, and a cooling medium flow path 10 for allowing a cooling medium to flow through the other main surface (hereinafter referred to as an outer surface). Is provided. Here, the fuel gas flow path 8 is formed in a serpentine shape (not shown), and similarly, the cooling medium flow path 10 is formed in a serpentine shape (see FIG. 3).

  Similarly, an oxidant gas is supplied to the cathode 4b on one main surface (hereinafter referred to as an inner surface) of the cathode separator 7b that is in contact with the cathode 4b, and the product generated by the electrode reaction or the unreacted fuel gas is supplied to the MEA5. A groove-like oxidant gas flow path 9 for carrying away to the outside is provided, and a cooling medium flow path 10 for allowing a cooling medium to flow through the other main surface (hereinafter referred to as an outer surface). Is provided. The oxidant gas channel 9 is a second oxidant gas channel (second reaction gas channel) (second reaction gas channel (first reaction gas channel) 9a and a second reaction gas channel (second reaction) formed so as to be joined to the gasket channel 31). (Gas flow path) 9b (see FIG. 4).

  As a result, fuel gas and oxidant gas are supplied to the anode 4a and the cathode 4b, respectively, and these gases react to generate electricity and heat. Further, by causing a cooling medium such as cooling water to flow through the cooling medium flow path 10, the generated heat is recovered, and the temperature inside the fuel cell 11 during power generation can be adjusted to be substantially constant.

  In the present embodiment, the fuel gas flow path 8 and the oxidant gas flow path 9 are formed by providing grooves on the inner surfaces of the separators 7a and 7b from the advantage that the manufacturing process can be simplified. Yes. Further, for the same advantages as described above, the cooling medium flow path 10 is also formed by providing grooves on the outer surfaces of the separators 7a and 7b.

  A plurality (for example, 20 cells) of the fuel cells 11 configured as described above are stacked, and a current collecting plate and an insulating plate (both not shown) are respectively disposed at both ends thereof, and both sides of the insulating plate are arranged. End plates (not shown) are respectively disposed on the plates and fastened with fasteners (not shown) to form the fuel cell stack 100. Each manifold hole such as a fuel gas supply manifold hole provided in the polymer electrolyte membrane 1 or the like is connected in the stacking direction to constitute each manifold such as a fuel gas supply manifold. That is, the fuel cell stack 100 of the present embodiment has a so-called “internal manifold type” configuration in which the separators 7a and 7b have manifolds.

  Next, the configuration of the cathode gasket 6b will be described in detail with reference to FIGS. In addition, the gasket flow path 31 is not provided in the anode gasket 6a. Since the basic configuration of the anode gasket 6a other than this is the same as that of the cathode gasket 6b, detailed description thereof is omitted.

[Composition of gasket]
2 shows a schematic configuration of one main surface of the cathode gasket 6b of the fuel cell 11 in the fuel cell stack 100 shown in FIG. 1 (main surface on the side in contact with the polymer electrolyte membrane 1; hereinafter referred to as an inner surface). It is a schematic diagram shown. In FIG. 2, the vertical direction of the cathode gasket 6b is represented as the vertical direction in the drawing, and a first oxidant gas flow path 9a of an oxidant gas flow path 9 described later is indicated by a two-dot chain line.

  As shown in FIG.1 and FIG.2, it is cyclic | annular and it is formed in the rectangle, The center opening is provided in the main surface (inner surface). The central opening is formed slightly larger than the main surface of the cathode catalyst layer 2b described later. Further, manifold holes such as an oxidant gas supply manifold hole 21 penetrating in the thickness direction are provided on the inner surface of the cathode gasket 6b. Here, two oxidant gas discharge manifold holes are provided.

  Specifically, the oxidant gas supply manifold hole 21 is provided on one side of the upper part of the cathode gasket 6b (the side on the left side of the drawing: hereinafter referred to as the first side), The oxidant gas discharge manifold hole 22a is provided on the other side of the oxidant gas supply manifold hole 21 (the right side of the drawing: hereinafter referred to as the second side), and the other oxidant gas discharge manifold hole 22a is provided. The manifold hole 22 b is provided below the oxidant gas supply manifold hole 21. The fuel gas supply manifold hole 23 is provided between the oxidant gas supply manifold hole 21 and the oxidant gas discharge manifold hole 22a in the upper part of the cathode gasket 6b. It is provided on the second side of the lower part of the gasket 6b. Further, the cooling medium supply manifold hole 25 is provided in the second side part at the upper part of the cathode gasket 6b, and the cooling medium discharge manifold hole 26 is provided in the first side part at the lower part of the cathode gasket 6b. It has been.

  In the first embodiment, each manifold hole such as the oxidant gas supply manifold hole is formed so that its opening shape is substantially a circle. However, the present invention is not limited to this. You may form in arbitrary shapes, such as a polygon.

  A gasket channel 31 is disposed on the inner surface of the cathode gasket 6b so as to surround the central opening (inner circumference) (so as to surround the cathode 4b). The gasket channel 31 is formed by a through groove that penetrates in the thickness direction. As shown in FIG. 1, the through groove that forms the gasket channel 31 is formed so that the peripheral edge of the polymer electrolyte membrane 1 is exposed (contacted).

  Further, as shown in FIG. 2, the gasket channel 31 is formed so that its upstream end is connected to the downstream end of the first oxidant gas channel 9a of the oxidant gas channel 9 described later, The downstream end is formed so as to be connected to the two oxidant gas discharge manifold holes 22a and 22b.

  Specifically, the upstream end of the gasket channel 31 is positioned above the fuel gas discharge manifold hole 24, and the gasket channel 31 is a flow formed so as to extend downward by a distance from the upstream end. It has a channel 31c and two channels 31a and 31b branched from the downstream end of the channel 31c. One branched flow path 31a extends in the horizontal direction from the downstream end of the flow path 31c toward the second side along the central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b). It extends a distance, from there it extends a distance above it, and extends from its arrival point a distance in the horizontal direction towards the first side. The flow path 31a extends upward from there to reach the oxidizing gas discharge manifold hole 22a. The other branched flow path 31b is horizontal along the central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b) from the downstream end of the flow path 31c toward the first side. It extends a distance in the direction and from there it extends a distance above it. And the flow path 31b is extended in the horizontal direction so that it may reach the manifold hole 22b for oxidizing gas discharge from the reaching point. In this way, the gasket flow path 31 is formed so as to surround the opening along the central opening of the cathode gasket 6b (the outer periphery of the cathode 4b) as a whole.

  Next, the cathode separator 7b will be described in detail with reference to FIG. 1, FIG. 3, and FIG. The anode separator 7a is not provided with a flow path joined to the gasket flow path 31, but is provided with a fuel gas flow path of a normal mode. The other configuration of the anode separator 7a is the same as the basic configuration of the cathode separator 7b, and a detailed description thereof will be omitted.

[Composition of separator]
FIG. 3 is a schematic diagram showing the outer shape of the cathode separator 7b of the fuel cell 11 in the fuel cell stack 100 shown in FIG. 1, and FIG. 4 shows the cathode separator 7b of the fuel cell 11 in the fuel cell stack 100 shown in FIG. It is a schematic diagram which shows the inner surface shape. 3 and 4, the vertical direction of the cathode separator 7b is represented as the vertical direction in the drawing, and the two-dot chain line represents the outer periphery of the cathode 4b.

  As shown in FIG. 3, the cathode separator 7 b is formed in a substantially rectangular shape, and manifold holes such as a fuel gas supply manifold hole 23 penetrating in the thickness direction are formed on the outer peripheral edge of the cathode separator 7 b. . A cooling medium flow path 10 is provided on the outer surface of the cathode separator 7 b so as to connect the cooling medium supply manifold hole 25 and the cooling medium discharge manifold hole 26. Here, the cooling medium flow path 10 is composed of one flow path groove, and is formed in a serpentine shape.

  Further, as shown in FIG. 4, an oxidant gas flow path 9 is arranged on the inner surface of the cathode separator 7b so as to connect the oxidant gas supply manifold hole 21 and the oxidant gas discharge manifold holes 22a and 22b. It is installed. Here, the oxidant gas flow path 9 is composed of one flow path groove, and the first oxidant gas flow formed in a serpentine shape so that the cathode 4b is exposed (in contact with the cathode 4b). It has a passage (first reaction gas passage) 9a and a second oxidant gas passage (second reaction gas passage) 9b formed so as to surround the outer periphery of the cathode 4b. The first oxidant gas channel 9 a constitutes an electrode contact portion of the oxidant gas channel 9.

  The first oxidant gas flow path 9a is formed such that its upstream end is connected to the oxidant gas supply manifold hole 21 and its downstream end is positioned on the outer periphery of the cathode 4b. It is substantially comprised by the part. The downstream end of the first oxidant gas flow path 9a is connected to the upstream end of a connection flow path 9c formed to extend in the vertical direction of the cathode separator 7b. The second oxidizing gas channel 9b has two channels 9b1 and 9b2, and the upstream ends of these channels are connected to the downstream ends of the connection channel 9c, respectively. Are connected to two oxidant gas discharge manifold holes 22a, 22b.

  Specifically, the first oxidant gas flow passage 9a extends from the oxidant gas supply manifold hole 21 by a distance in the direction of the fuel gas discharge manifold hole 24 (that is, the diagonally lower right direction in FIG. 2). Extending a distance in the horizontal direction from the second side. Then, from that point of extension, it extends a distance below, from there it extends a distance in the horizontal direction towards the first side, and from there it extends a distance below. Then, the extended pattern is repeated three times, and from there, it extends a distance in the horizontal direction toward the second side portion, and extends downward from the reaching point to reach the lower portion of the outer periphery of the cathode 4b. . Such a portion extending in the horizontal direction of the first oxidant gas flow path 9a constitutes a reciprocating portion, and a portion extending downward constitutes an inverting portion.

  In addition, one branched flow path 9b1 in the second oxidant gas flow path 9b extends a distance in the horizontal direction from the downstream end of the connection flow path 9c toward the second side along the outer periphery of the cathode 4b. From there, it extends a distance above it, and from that point it extends a distance in the horizontal direction towards the first side. The flow path 9b1 extends upward from there to reach the oxidant gas discharge manifold hole 21a. The other branched flow path 9b2 extends along the outer periphery of the cathode 4b from the downstream end of the connection flow path 9c in the horizontal direction toward the first side, and extends from there upward distance. ing. The flow path 9b2 extends in the horizontal direction so as to reach the oxidizing gas discharge manifold hole 22b from the reaching point. Thus, the second oxidant gas flow path 9b is formed so as to surround the outer periphery of the cathode 4b as a whole. That is, the second oxidant gas flow path 9b is formed so as to overlap (substantially match here) the gasket flow path 31 when viewed from the thickness direction of the cathode separator 7b, and the thickness of the cathode separator 7b. In the direction, it is joined to the gasket channel 31 (see FIG. 1).

  In addition, the oxidant gas flow path 9 in this Embodiment is formed so that it may become the same as the pressure loss of the oxidant gas flow path of a normal aspect. That is, L is the ratio between the total flow path length L of the oxidant gas flow path in the normal mode and the cross-sectional area perpendicular to the oxidant gas flow in the oxidant gas flow path (hereinafter simply referred to as cross-sectional area) S / S and L3 / S1, which is the ratio of the total flow path length L3 of the oxidant gas flow path 9 in the present embodiment to the cross-sectional area S1 of the oxidant gas flow path 9, match the first and second The groove width and groove depth of the dioxidant gas flow paths 9a and 9b and the connection flow path 9c, and the groove width and groove depth of the gasket flow path 31 (thickness of the cathode gasket 6b) are adjusted.

  In addition, the connection flow path 9c and the second oxidant gas flow path 9b are configured so that the pressure loss of the flow path constituted by the connection flow path 9c, the second oxidant gas flow path 9b, and the gasket flow path 31 is reduced by the first oxidation. It is formed so as not to change compared with the agent gas flow path 9a. Here, the cross-sectional area S3 of the flow path constituted by the connection flow path 9c, the second oxidant gas flow path 9b, and the gasket flow path 31 matches the cross-sectional area S2 of the first oxidant gas flow path 9a. As described above, the groove width and groove depth of the first and second oxidant gas flow paths 9a and 9b and the connection flow path 9c, and the groove width and groove depth of the gasket flow path 31 (the thickness of the cathode gasket 6b). ) Has been adjusted.

  As a result, the oxidant gas is supplied from the oxidant gas supply manifold hole 21 to the upstream end of the first oxidant gas flow path 9a, and the supplied oxidant gas flows through the first oxidant gas flow path 9a. Are supplied to the flow path constituted by the connection flow path 9c, the second oxidant gas flow path 9b, and the gasket flow path 31, and flow through the flow path to the oxidant gas discharge manifold holes 21a and 21b. Discharged.

  Next, the effect of the fuel cell stack 100 according to the first embodiment will be described with reference to FIGS. 1 to 4.

[Operation effect of fuel cell stack]
First, from the fuel gas supply manifold or the oxidant gas supply manifold of the fuel cell stack 100 to the fuel gas flow path 8 or the first oxidant gas flow path 9a of each fuel cell 11 constituting the fuel cell stack 100. , Humidified fuel gas or oxidant gas is supplied. While the fuel gas or oxidant gas supplied to the fuel gas channel 8 or the first oxidant gas channel 9a flows through the fuel gas channel 8 or the first oxidant gas channel 9a, respectively. Are supplied to the anode 4a or the cathode 4b.

At the anode 4a, a reaction of H ₂ → 2H ⁺ + 2e ⁻ occurs, and at the cathode 4b, a reaction of 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O occurs to generate water (water vapor). In addition, electricity and heat are generated with these reactions. A part of the water generated at the cathode 4b moves to the anode 4a side by so-called reverse diffusion.

  The water vapor generated in this way (including water vapor for humidifying the reaction gas before being supplied to the fuel cell stack 100), together with the unreacted fuel gas or oxidant gas, Alternatively, it flows through the first oxidant gas flow path 9a. For this reason, an oxidant gas sufficiently containing water vapor flows through the downstream portion of the first oxidant gas flow path 9a.

  Then, the oxidant gas sufficiently containing water vapor is supplied to the flow path constituted by the second oxidant gas flow path 9 b and the gasket flow path 31. The second oxidant gas flow path 9b and the gasket flow path 31 are disposed at the peripheral edge of the fuel cell 11 (polymer electrolyte membrane 1), and the peripheral edge of the fuel cell 11 is close to the atmosphere. The temperature is lower than its central part.

  For this reason, it is possible to easily condense the water vapor while the oxidizing gas sufficiently containing water vapor flows through the flow path constituted by the second oxidizing gas flow path 9b and the gasket flow path 31. And since this condensed water is supplied to the peripheral part of the polymer electrolyte membrane 1, drying of the peripheral part of the polymer electrolyte membrane 1 can be suppressed.

  In the present embodiment, the entire gasket channel 31 is formed by a through groove penetrating in the thickness direction. However, the present invention is not limited to this, for example, only the channel 31c is formed by a through groove, It is good also as a structure which forms the flow paths 31a and 31b by the groove | channel which does not penetrate in the thickness direction, and also forms the gasket flow path 31 in the groove shape in the inner surface of the cathode gasket 6b, and the through-hole which penetrates the upstream end in the thickness direction It is good also as a structure connected to the connection flow path 9c.

  Further, the cross-sectional area S3 of the flow path constituted by the connection flow path 9c, the second oxidant gas flow path 9b, and the gasket flow path 31 coincides with the cross-sectional area S2 of the first oxidant gas flow path 9a. As described above, the groove width and groove depth of the first and second oxidant gas flow paths 9a and 9b and the connection flow path 9c, and the groove width and groove depth of the gasket flow path 31 (the thickness of the cathode gasket 6b). However, the present invention is not limited to this, and the connection flow path 9c and the second oxidant gas flow path 9b are formed by the connection flow path 9c, the second oxidant gas flow path 9b, and the gasket flow path 31. If the pressure loss of the passage does not change compared to the first oxidant gas flow path 9a, the groove width and depth of the first and second oxidant gas flow paths 9a and 9b and the connection flow path 9c, and The groove width and groove depth of the gasket channel 31 (the thickness of the cathode gasket 6b) can be arbitrarily set. Kill.

(Embodiment 2)
The basic configuration of the fuel cell stack according to Embodiment 2 of the present invention is the same as that of the fuel cell stack 100 according to Embodiment 1, but the coolant flow path 10 disposed on the outer surface of the cathode separator 7b. The configuration differs as follows.

[Composition of separator]
FIG. 5 is a schematic diagram showing the outer shape of the cathode separator of the fuel cell in the fuel cell stack according to Embodiment 2 of the present invention. In FIG. 5, the vertical direction of the cathode separator is represented as the vertical direction in the figure.

  In the second embodiment, the cooling medium flow path 10 in the cathode separator 7b is formed so as to surround the upper part of the cathode 4b along the outer periphery of the cathode 4b. Here, the upper portion of the cathode 4b refers to a portion facing the upstream portion of the first oxidant gas flow path 9a in the cathode 4b. The upstream portion 10c of the cooling medium flow path has one end of the cooling medium flow path 10 as a connection end of the cooling medium supply manifold hole 23, which is the upstream end of the cooling medium flow path 10, and the other end of the formula: L1. The portion satisfying ≦ L2, and the portion between them. In the above formula, L1 indicates the flow path length of the upstream portion 10c of the cooling medium flow path 10, and L2 indicates the total flow path length of the cooling medium flow path 10.

  Specifically, the upstream portion 10c of the cooling medium flow path 10 extends a distance below the cooling medium supply manifold hole 23 and branches there into two flow paths 10a and 10b. One branched flow path 10a extends along the outer periphery of the cathode 4b from the branch point toward the first side by a distance in the horizontal direction, and from there, the first side portion side of the outer periphery of the cathode 4b. It extends down to the approximate center of the end and folds back at its arrival point. Then, the flow path 10a extends from the turning point along the outer circumference of the cathode 4b by a distance that extends upward, and then extends a distance that extends in the horizontal direction toward the second side portion, and from the arrival point to the bottom. It extends for a certain distance and merges with the other flow path 10b. The other channel 10b extends along the outer periphery of the cathode 4b from the branch point toward the second side by a distance in the horizontal direction, and from there, the second side of the outer periphery of the cathode 4b. The distance extends down to the approximate center of the end and is turned back at that point. The flow path 10b extends from the turn-up point a distance above, reaches from the arrival point a distance in the horizontal direction toward the first side, and merges with the flow path 10a.

  In this way, the upstream portion 10c of the cooling medium flow path 10 through which the low-temperature cooling medium flows before absorbing the heat generated during the reaction between the fuel gas and the oxidant gas in the fuel cell 11 is the thickness of the cathode separator 7b. When viewed from the direction, by providing the upper portion of the peripheral portion of the cathode separator 7b, the temperature of the upper portion of the peripheral portion of the cathode separator 7b can be made lower than that of the central portion of the cathode separator 7b.

For example, the fuel gas and the oxidant gas are supplied so that the dew point of the fuel gas and oxidant supply manifold holes 23 and 21 in the fuel cell 11 in which the area of the anode 4a and the cathode 4b is 100 cm ² is 65 ° C. Assume that the stack 100 is operated at a current density of 0.3 A / cm ² . Assuming that 10% of the generated water moves from the cathode 4b to the anode 4a, the dew point of the fuel gas discharge manifold hole 24 rises to 85 ° C., and the dew point of the oxidant gas discharge manifold hole 22 rises to 72 ° C. In such a case, the temperature and flow rate of the cooling medium supplied to the upstream portion 10c of the cooling medium flow path 10 are adjusted in consideration of the thermal conductivity of the separators 7a and 7b of the fuel cell stack 100. The temperature of the upper part of the peripheral edge of the cathode separator 7b can be made lower than the dew point of the gas or oxidant gas discharge manifold holes 24 and 22.

  For this reason, the water vapor | steam which flows through the flow path comprised from the gasket flow path 31 and the 2nd oxidizing gas flow path 9b can be condensed more easily. In addition, the upper part of the cathode 4b is less likely to dry due to the reaction between hydrogen and oxygen than the lower part of the cathode 4b. Since the cooling water flow path 10 is comprised as mentioned above, drying of the upper part of the peripheral part of the polymer electrolyte membrane 1 can be suppressed more.

  The amount of water vapor condensed in the flow path constituted by the gasket flow path 31 and the second oxidant gas flow path 9b is adjusted by adjusting the temperature and flow rate of the cooling medium supplied to the cooling medium flow path 10. It is preferable to do.

  Here, the upstream portion 10c of the cooling medium flow path 10 provided at the peripheral edge of the cathode separator 7b branches into a plurality of flow paths (here, two flow paths 10a and 10b), and then merges. Although it was set as the structure connected to the downstream part of a cooling medium flow path, it is good also as a structure connected to the downstream part of the cooling medium flow path 10 without joining.

(Embodiment 3)
The basic configuration of the fuel cell stack according to Embodiment 3 of the present invention is the same as that of the fuel cell stack 100 according to Embodiment 2, but the coolant flow path 10 disposed on the outer surface of the cathode separator 7b. The configuration of the upstream portion 10c is different as follows.

[Composition of separator]
FIG. 6 is a schematic diagram showing the outer shape of the cathode separator of the fuel cell in the fuel cell stack according to Embodiment 3 of the present invention. In FIG. 6, the vertical direction of the cathode separator is represented as the vertical direction in the figure.

  As shown in FIG. 6, the upstream portion 10c of the cooling medium flow path 10 in the cathode separator 7b of Embodiment 3 is formed such that the branched flow paths 10a and 10b surround the entire outer periphery of the cathode 4b. Specifically, one branched flow path 10a extends along the outer circumference of the cathode 4b from the branch point toward the first side by a distance in the horizontal direction, and from there, extends at a distance below, It wraps around at the arrival point. Then, the flow path 10a extends from the turning point along the outer circumference of the cathode 4b by a distance that extends upward, and then extends a distance that extends in the horizontal direction toward the second side portion, and from the arrival point to the bottom. It extends for a certain distance and merges with the other flow path 10b. The other flow path 10b extends along the outer periphery of the cathode 4b from the branch point by a distance below, extends from there for a distance in the horizontal direction toward the first side, and turns back at the arrival point. ing. Then, the flow path 10b extends from the turning point in a horizontal direction toward the second side portion, extends from there to an upper distance, and extends horizontally from the reaching point toward the first side portion. It extends a certain distance in the direction and merges with the flow path 10a.

  As a result, the upstream portion 10c of the cooling medium flow path 10 through which the cooling medium having a low temperature before the heat generated when the fuel cell 11 reacts with the fuel gas and the oxidant gas flows is connected to the cathode separator 7b in the thickness direction. As a result, the temperature of the entire peripheral portion of the cathode separator 7b is lower than that of the central portion of the cathode separator 7b by providing the substantially entire peripheral portion of the cathode separator 7b corresponding to the gasket channel 31. Can do. For this reason, it is possible to more easily condense the water vapor flowing through the flow path composed of the gasket flow path 31 and the second oxidant gas flow path 9b, and to further dry the entire periphery of the polymer electrolyte membrane 1. Can be suppressed.

  The amount of water vapor condensed in the flow path constituted by the gasket flow path 31 and the second oxidant gas flow path 10b is adjusted by adjusting the temperature and flow rate of the cooling medium supplied to the cooling medium flow path 10. It is preferable to do. Here, the upstream portion 10c of the cooling medium flow path 10 provided at the peripheral edge of the cathode separator 7b branches into a plurality of flow paths (here, two flow paths 10a and 10b), and then merges. Although it was set as the structure connected to the downstream part of a cooling medium flow path, it is good also as a structure connected to the downstream part of the cooling medium flow path 10 without joining.

(Embodiment 4)
The basic configuration of the fuel cell stack according to Embodiment 4 of the present invention is the same as that of the fuel cell stack 100 according to Embodiment 1, but the configurations of the cathode gasket 6b and the cathode separator 7b are different as follows.

[Composition of gasket]
FIG. 7 is a schematic diagram showing the inner shape of the cathode gasket of the fuel cell in the fuel cell stack according to Embodiment 4 of the present invention. In addition, in FIG. 7, the up-down direction in the cathode gasket is represented as the up-down direction in the figure.

  As shown in FIG. 7, one oxidant gas discharge manifold hole is provided on the inner surface of the cathode gasket 6 b of the fourth embodiment, and downstream of the gasket channels 31 in the flow paths 31 a and 31 b. The end is arranged to communicate with the one oxidant gas discharge manifold hole 22.

  Specifically, the oxidant gas discharge manifold hole 22 is provided on the second side of the fuel gas discharge manifold hole 24. Further, the flow path 31a of the gasket flow path 31 extends from the downstream end of the flow path 31c along the central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b) and from the branch point to the second side. It extends a distance in the horizontal direction toward the part, extends a distance in the upward direction from there, extends a distance in the horizontal direction from there to the first side part, and turns back at the reaching point. The flow path 31a extends from the turn-back point by a distance in the horizontal direction toward the second side portion, extends from there by a distance below, and reaches the oxidant gas discharge manifold hole 22 from the reaching point. It extends so that. The other branched flow path 31b is horizontal along the central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b) from the downstream end of the flow path 31c toward the first side. It extends a certain distance in the direction, from there it extends a distance above it, and it turns back at its arrival point. The flow path 31b extends downward from the reaching point, and then extends a distance in the horizontal direction toward the second side portion. From the reaching point, the flow path 31b enters the oxidizing gas discharge manifold hole 22. It extends to reach.

  The gasket channel 31 is a through-groove that penetrates in the thickness direction so that the channel until branched to the channels 31 a and 31 b communicates with the second oxidant gas channel 9 b of the oxidant gas channel 9. However, the flow paths 31a and 31b are formed by grooves that do not penetrate.

[Composition of separator]
FIG. 8 is a schematic diagram showing the inner shape of the cathode separator of the fuel cell in the fuel cell stack according to Embodiment 4 of the present invention. In FIG. 8, the vertical direction of the cathode separator is represented as the vertical direction in the figure.

  As shown in FIG. 8, one oxidant gas discharge manifold hole is provided on the inner surface of the cathode separator 7b of the fourth embodiment, and the downstream end of the oxidant gas passage 9 is connected to the downstream end. The downstream end of the path 9 is used.

  Specifically, the oxidant gas discharge manifold hole 22 is provided on the second side of the fuel gas discharge manifold hole 24. The connection channel 9c of the oxidant gas channel 9 is formed so as to overlap with the channel 31c of the cathode gas channel 31 as viewed from the thickness direction of the cathode separator 7b, and communicates with the channel 31c. Yes. Thereby, the oxidant gas flowing through the oxidant gas flow path 9 flows through the flow paths 31a and 31b of the gasket flow path 31 via the flow path constituted by the connection flow path 9c and the flow path 31c. .

  The fuel cell stack according to the fourth embodiment configured as described above also exhibits the same operational effects as the fuel cell stack 100 according to the first embodiment.

  In the present embodiment, the second oxidant gas flow path 9b is not provided on the inner surface of the cathode separator 7b. However, the present invention is not limited to this, and the second oxidant gas flow path 9b may be provided. Good.

(Embodiment 5)
The fuel cell stack according to Embodiment 5 of the present invention has the same basic configuration as the fuel cell stack according to Embodiment 4, but the oxidant gas flow in the cathode flow path 31 in the cathode gasket 6b and the cathode separator 7b. The configuration of the path 9 is different as follows.

[Composition of gasket]
FIG. 9 is a schematic diagram showing the inner shape of the cathode gasket of the fuel cell in the fuel cell stack according to Embodiment 5 of the present invention. In FIG. 9, the vertical direction of the cathode gasket is shown as the vertical direction in the figure.

  As shown in FIG. 9, on the inner surface of the cathode gasket 6b, a groove-like channel 31a connected to a channel 31c1 made of a through groove and a groove-like channel connected to a channel 31c2 made of a through groove. And a gasket channel 31 comprising 31b.

  The flow path 31c1 is formed so that its upstream end is positioned below the fuel gas discharge manifold hole 23 and extends upward, and its downstream end is connected to the upstream end of the flow path 31a. The flow path 31a extends from the upstream end along a central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b) toward the second side portion by a distance in the horizontal direction. The lower end is connected to the oxidant gas discharge manifold hole 22, extending at a distance below, reaching from the reaching point to the oxidant gas discharge manifold hole 22.

  On the other hand, the flow path 31c2 is formed so that its upstream end is positioned below the oxidant gas discharge manifold hole 21 and extends in the horizontal direction toward the first side, and its downstream end It is connected to the upstream end of the path 31b. The flow path 31b extends from the upstream end along a central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b) to a lower distance, and from there toward the second side portion. It extends a certain distance in the horizontal direction, extends from its reaching point to reach the oxidant gas discharge manifold hole 22, and its downstream end is connected to the oxidant gas discharge manifold hole 22.

[Composition of separator]
FIG. 10 is a schematic diagram showing the inner shape of the cathode separator of the fuel cell in the fuel cell stack according to Embodiment 5 of the present invention. In FIG. 10, the vertical direction of the cathode separator is represented as the vertical direction in the figure.

  As shown in FIG. 10, a first oxidant gas flow path 9a and connection flow paths 9c1 and 9c2 are disposed on the inner surface of the cathode separator 7b. The first oxidant gas flow path 9a is divided into a serpentine flow path 9a3 formed in a serpentine shape and a peripheral flow formed so as to be branched from the downstream end of the serpentine flow path 9a3 along the peripheral edge of the cathode 4b. The roads 9a1 and 9a2 are configured.

  Specifically, the peripheral channel 9a1 extends from the upstream end thereof by a distance in the horizontal direction toward the second side portion, extends from there by an upper distance, and then extends from there to the first side portion. It extends a certain distance in the horizontal direction, and extends an upper distance so as to reach the outer periphery of the cathode 4b from the arrival point. The peripheral flow path 9a2 extends from the upstream end by a distance in the horizontal direction toward the first side, extends from there by an upper distance, and reaches the outer periphery of the cathode 4b from the reaching point. In addition, it extends a distance in the horizontal direction towards the first side.

  Further, the connection flow paths 9c1 and 9c2 are formed so as to overlap the flow paths 31c1 and 31c2 of the gasket flow path 31 described above when viewed from the thickness direction of the cathode separator 7b, and are joined to the gasket flow path 31. .

  Thereby, in the fuel cell stack according to the fifth embodiment, the oxidant gas is supplied from the peripheral flow paths 9a1 and 9a2 of the first oxidant gas flow path 9a to the peripheral edge of the cathode 4b, so that the connection flow path 9c1 , 9 c 2 and the gasket channel 31, water is supplied to the peripheral portion of the polymer electrolyte membrane 1 not only from the peripheral portion of the cathode 4 b. In other words, moisture is supplied to the polymer electrolyte membrane 1 from both the inside and outside of the outer periphery of the cathode 4b when viewed from the thickness direction of the cathode separator 7b. For this reason, the deterioration by the drying of the peripheral part of the polymer electrolyte membrane 1 can be suppressed more.

(Embodiment 6)
The basic configuration of the fuel cell stack according to Embodiment 6 of the present invention is the same as that of the fuel cell stack 100 according to Embodiment 1, but the configurations of the cathode gasket 6b and the cathode separator 7b are different as follows.

[Composition of gasket]
FIG. 11 is a schematic diagram showing the inner shape of the cathode gasket of the fuel cell in the fuel cell stack according to Embodiment 6 of the present invention. In addition, in FIG. 11, the up-down direction in a cathode gasket is represented as the up-down direction in a figure.

  As shown in FIG. 11, three oxidant gas discharge manifold holes 22a, 22b, and 22c are provided on the inner surface of the cathode gasket 6b of the sixth embodiment. The fuel gas discharge manifold hole 24 is provided on the second side portion side. In addition, the oxidant gas supply manifold hole 21 is formed in a long hole shape that is long in the vertical direction (a shape in which two sides of the short line are replaced with two semicircular sides).

  The gasket channel 31 is composed of channels 31a and 31b formed of through grooves, and the upstream end of the channel 31a is located above the oxidant gas discharge manifold hole 22c, and its downstream end. Is connected to the oxidant gas discharge manifold hole 22a. On the other hand, the upstream end of the flow path 31b is located below the fuel gas discharge manifold hole 24, and the downstream end thereof is connected to the oxidant gas discharge manifold hole 22b.

  The flow path 31a is formed so as to extend in the horizontal direction from the upstream end toward the second side portion, and from there along the central opening (inner circumference) of the cathode gasket 6b (cathode 4b). A distance extending in the upward direction (from the outer periphery of the gas sensor), extending a distance horizontally toward the first side portion, and extending from the reaching point to the manifold hole 22a for discharging the oxidant gas. ing. The flow path 31b extends downward from the upstream end thereof, and from there along the central opening (inner periphery) of the cathode gasket 6b (along the outer periphery of the cathode 4b), the first side portion. It extends a distance in the horizontal direction toward the upper side, extends from there by a distance in the upward direction, and extends from the reaching point to the manifold hole 22b for oxidizing gas discharge.

[Composition of separator]
FIG. 12 is a schematic diagram showing the inner shape of the cathode separator of the fuel cell in the fuel cell stack according to Embodiment 6 of the present invention. In FIG. 12, the vertical direction of the cathode separator is shown as the vertical direction in the figure.

  As shown in FIG. 12, a plurality (here, four) of groove-like oxidant gas flow paths 91 to 94 are arranged on the inner surface of the cathode separator 7b of the sixth embodiment. The first oxidant gas flow paths 91a to 94a, which are electrode contact portions of the oxidant gas flow paths 91 to 94, are formed in a serpentine shape and run in parallel.

  Further, second oxidant gas flow paths 91b and 94b, which are downstream portions of the electrode contact portions in the pair of outermost oxidant gas flow paths 91 and 94, are arranged along the outer periphery of the cathode 4b and It is formed so as to surround the outer periphery of the cathode 4 b, is formed so as to overlap with the gasket channel 31 when viewed from the thickness direction of the cathode separator 7 b, and is joined to the gasket channel 31. The downstream ends of the second oxidant gas flow paths 91b and 94b are connected to the oxidant gas discharge manifold holes 22a and 22b, respectively. On the other hand, the second oxidant gas passages 92b and 93b, which are downstream portions of the oxidant gas passages 92 and 93, are formed so as to reach the oxidant gas discharge manifold hole 22c. The oxidant gas discharge manifold hole 22c is connected.

  In addition, the oxidant gas flow paths 91 to 94 in the present embodiment are formed so as to be the same as the pressure loss of the oxidant gas flow path of the normal mode. Further, the second oxidant gas flow paths 91b and 94b have the pressure loss of the flow path constituted by the second oxidant gas flow paths 91b and 94b and the gasket flow path 31, and the second oxidant gas flow paths 91b and 94b. It is formed so as not to change compared with the pressure loss of the flow path such as the first oxidizing gas flow path 91a other than the above. Here, the cross-sectional area S4 of the flow path constituted by the second oxidant gas flow paths 91b and 94b and the gasket flow path 31, and the first oxidant gas flow path 91a other than the second oxidant gas flow paths 91b and 94b. The groove width and groove depth of the oxidant gas channels 91 to 94, and the groove width and groove depth of the gasket channel 31 (thickness of the cathode gasket 6b) so that the cross-sectional areas S5 and the like coincide with each other. It has been adjusted.

  Thus, the fuel cell stack according to Embodiment 6 in which a plurality of oxidant gas flow paths are formed also has the same effects as the fuel cell stack 100 according to Embodiment 1.

  In the present embodiment, the oxidant gas supply manifold hole 21 is formed in the shape of a long hole that is long in the vertical direction. However, the shape is not limited to this, and the shape is arbitrary. In addition, the entire gasket channel 31 is configured with a through groove penetrating in the thickness direction. However, the present invention is not limited to this. For example, a portion from the upstream ends of the channels 31a and 31b to a certain distance is formed with a through groove, It is good also as a structure which forms a part other than by a groove | channel. Further, the gasket channel 31 is formed in a groove shape on the inner surface of the cathode gasket 6b, and the upstream end thereof is communicated with the downstream ends of the first oxidant gas channels 91a and 94a through a through hole penetrating in the thickness direction. Also good. Furthermore, it is good also as a structure which does not provide the 2nd oxidizing gas flow paths 91b and 94b of the oxidizing gas flow paths 91 and 94. FIG.

(Embodiment 7)
The fuel cell stack according to Embodiment 7 of the present invention has the same basic configuration as the fuel cell stack 100 according to Embodiment 6, but the configuration of the cathode separator 7b is different as follows.

[Composition of separator]
FIG. 13 is a schematic diagram showing the inner shape of the cathode separator of the fuel cell in the fuel cell stack according to Embodiment 7 of the present invention. In FIG. 13, the vertical direction of the cathode separator is represented as the vertical direction in the figure.

  As shown in FIG. 13, a plurality of (here, four) groove-like oxidant gas flow paths 91 to 94 are disposed on the inner surface of the cathode separator 7b of the seventh embodiment. In the middle of the first oxidant gas flow paths 91a to 94a in the gas flow paths 91 to 94 (here, downstream of the first oxidant gas flow paths 91a to 94a), the first oxidant gas flow paths 91a to 91a. A recess 95 is formed so as to communicate with 94a.

  The hollow portion 95 is formed in a substantially trapezoidal shape when viewed from the thickness direction of the cathode separator 7b, and has a plurality of island-like shapes (here, substantially columnar shapes, more accurate) protruding from the bottom surface in the thickness direction. Is provided with a substantially 96-shaped projection 96. A plurality of projections 96 (here, 12) are formed at an equal pitch. Here, the protrusion 96 is formed in a substantially cylindrical shape, but is not limited thereto, and may be a substantially cylindrical shape, a substantially triangular prism shape, and a substantially quadrangular prism shape. In addition, here, the circular cross section perpendicular to the standing direction of the protrusion 27 is a substantially true cylindrical shape, but is not limited thereto, and may be an elliptical cylindrical shape. Moreover, the hollow part 95 is formed in the same depth as 1st oxidizing gas flow path 91a-94a.

  As a result, the oxidant gas flowing through the first oxidant gas flow paths 91 a to 94 a is merged in the recess 95. The oxidant gas merged in the depression 95 is disturbed in its flow by a plurality of projections 96 arranged in an island shape in the depression 95, and mixing of these gases is promoted, and the pressure of the oxidant gas is made uniform. Is planned. The mixed oxidant gas is diverted from the downstream end of the recess 95 to the first oxidant gas flow paths 91a to 94a. For this reason, the difference in the pressure loss of the oxidant gas flowing through the oxidant gas flow paths 91 to 94 can be reduced.

  Also in the fuel cell stack according to Embodiment 7 configured as described above, the same operational effects as those of the fuel cell stack 100 according to Embodiment 1 are exhibited.

  In the present embodiment, the recess 95 and the protrusion 96 are arranged downstream of the first oxidant gas flow paths 91a to 94a (side closer to the second oxidant gas flow path). However, it may be arranged upstream of the first oxidant gas flow paths 91a to 94a.

(Embodiment 8)
The fuel cell stack according to Embodiment 8 of the present invention has the same basic configuration as the fuel cell stack 100 according to Embodiment 1, but a subgasket is disposed between the polymer electrolyte membrane and the gasket. The point is different.

[Configuration of fuel cell stack]
FIG. 14 is a cross-sectional view schematically showing a schematic configuration of the fuel cell stack according to Embodiment 8 of the present invention. In FIG. 14, a part is omitted.

  As shown in FIG. 14, in the fuel cell 11 in the fuel cell stack 100 according to the eighth embodiment, a pair of cross-sectional shapes are substantially rectangular and annular anode subgaskets 13 a across the periphery of the polymer electrolyte membrane 1 and A cathode subgasket 13b is provided. Further, manifold holes such as a fuel gas supply manifold hole are provided at the peripheral edge portions of the anode gasket 6a and the cathode gasket 6b (not shown).

  The anode subgasket 13a and the cathode subgasket 13b are formed to have the same shape as the anode gasket 6a and the cathode gasket 6b when viewed from the stacking direction of the cells 11 (the thickness direction of the cathode separator 7b). The cathode subgasket 13b is formed with a through groove 32 penetrating in the thickness direction so as to overlap the gasket channel 31 when viewed from the stacking direction of the cells 11, and the through groove 32 is formed in the subgasket flow. A path 32 is formed. The sub-gasket channel 32 is joined to the gasket channel 31.

  The material constituting the anode subgasket 13a and the cathode subgasket 13b is not particularly limited as long as it has excellent gas sealability and appropriate rigidity. For example, PP (polypropylene), PET (polyethylene terephthalate) ), Resin films such as PPS (polyphenylene sulfide), fluorine-based synthetic resin films such as PTFE (polytetrafluoroethylene), rubber-like sheets (sheets made of fluororubber, etc.) such as fluorine-based synthetic resin sheets, or elastic resins And a composite sheet of a rigid resin.

  In this embodiment, the gasket flow path 31 is provided in the cathode gasket 6b and the sub gasket flow path 32 is provided in the cathode subgasket 13b. However, the present invention is not limited to this, and the anode gasket 6a is not limited thereto. It is good also as a structure which arrange | positions the gasket flow path 31 to the anode sub gasket 13a, and arrange | positions the gasket flow path 31 to both the anode gasket 6a and the cathode gasket 6b, It is good also as a structure which arrange | positions the subgasket flow path 32 in both the anode subgasket 13a and the cathode subgasket 13b.

  Further, in the present embodiment, the subgasket channel 32 is configured by a through groove penetrating in the thickness direction. However, the present invention is not limited to this, so that an oxidizing gas flows through the subgasket channel 32, for example, A part from the upstream end may be formed as a through groove, and the other part of the subgasket channel 32 may be formed as a groove that does not penetrate in the thickness direction.

  Further, in the present embodiment, the pressure loss of the flow path constituted by the second oxidant gas flow path 9b, the gasket flow path 31, and the subgasket flow path 32, and the pressure of the first oxidant gas flow path 9a. The loss is configured to match. Specifically, here, the cross-sectional area S6 of the flow path constituted by the second oxidant gas flow path 9b, the gasket flow path 31, and the sub-gasket flow path 32, and the breakage of the first oxidant gas flow path 9a. The groove width and groove depth of the first and second oxidant gas flow paths 9a and 9b, the groove width and groove depth of the gasket flow path 31 (the thickness of the cathode gasket 6b) so that the area S1 matches. ), And the groove width and depth of the subgasket channel 32 (the thickness of the cathode subgasket 13b) are adjusted.

  Thereby, when the fuel cell stack 100 is assembled, the pressure applied to the polymer electrolyte membrane 1 can be made uniform by the anode subgasket 13a and the cathode subgasket 13b. For this reason, damage to the polymer electrolyte membrane 1 can be suppressed. Further, the water vapor contained in the oxidant gas flowing through the flow path constituted by the second oxidant gas flow path 9b, the gasket flow path 31, and the subgasket flow path 32 is condensed, and the condensed water is increased. By supplying to the peripheral part of the molecular electrolyte membrane 1, drying of the peripheral part of the polymer electrolyte membrane 1 can be suppressed.

  In the first to eighth embodiments, the gasket flow path 31 is provided in the cathode gasket 6b. However, the present invention is not limited thereto, and the anode flow path 31 may be provided in the anode gasket 6a. The gasket channel 31 may be provided in both the anode gasket 6a and the cathode gasket 6b.

  Moreover, in the said Embodiment 1-8, although the fuel cell stack 100 was comprised as what is called an internal manifold type, it is not limited to this, You may comprise as what is called an external manifold type.

  The fuel cell and fuel cell system of the present invention can be applied to fuel cells using polymer solid electrolyte membranes, particularly stationary cogeneration systems, electric vehicles, etc., by suppressing deterioration due to drying of the polymer electrolyte membranes. It is useful in the field of fuel cells and the like.

1 is a cross-sectional view schematically showing a schematic configuration of a fuel cell stack according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing a schematic configuration of one main surface of a cathode gasket of a fuel cell in the fuel cell stack shown in FIG. 1. It is a schematic diagram which shows the outer surface shape of the cathode separator of the fuel cell in the fuel cell stack shown in FIG. It is a schematic diagram which shows the inner surface shape of the cathode separator of the fuel cell in the fuel cell stack shown in FIG. It is a schematic diagram which shows the outer surface shape of the cathode separator of the fuel cell in the fuel cell stack which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows the outer surface shape of the cathode separator of the fuel cell in the fuel cell stack which concerns on Embodiment 3 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode gasket of the fuel cell in the fuel cell stack which concerns on Embodiment 4 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode separator of the fuel cell in the fuel cell stack which concerns on Embodiment 4 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode gasket of the fuel cell in the fuel cell stack which concerns on Embodiment 5 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode separator of the fuel cell in the fuel cell stack which concerns on Embodiment 5 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode gasket of the fuel cell in the fuel cell stack which concerns on Embodiment 6 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode separator of the fuel cell in the fuel cell stack which concerns on Embodiment 6 of this invention. It is a schematic diagram which shows the inner surface shape of the cathode separator of the fuel cell in the fuel cell stack which concerns on Embodiment 7 of this invention. It is sectional drawing which shows typically schematic structure of the fuel cell stack which concerns on Embodiment 8 of this invention. 1 is a cross-sectional view schematically showing a schematic configuration of a solid polymer electrolyte fuel cell stack disclosed in Patent Document 1. FIG.

Explanation of symbols

1 Polymer electrolyte membrane (electrolyte layer)
2a Anode catalyst layer 2b Cathode catalyst layer 3a Anode gas diffusion layer 3b Cathode gas diffusion layer 4a Anode 4b Cathode 5 MEA (Membrane-Electrode-Assembly: electrolyte layer-electrode assembly)
6a Anode gasket 6b Cathode gasket 7a Anode separator 7b Cathode separator 8 Fuel gas flow path 9 Oxidant gas flow path 9a First oxidant gas flow path 9a1 Peripheral flow path 9a2 Peripheral flow path 9a3 Serpentine flow path 9b Second oxidant gas flow Channel 9b1 Channel 9b2 Channel 9c Connection channel 9c1 Connection channel 9c2 Connection channel 10 Cooling medium channel 10a Upstream part 11 Fuel cell 13a Anode subgasket 13b Cathode subgasket 21 Oxidant gas supply manifold hole 22 Oxidant gas Exhaust manifold hole 22a Oxidant gas discharge manifold hole 22b Oxidant gas discharge manifold hole 22c Oxidant gas discharge manifold hole 23 Fuel gas supply manifold hole 24 Fuel gas discharge manifold hole 25 Cooling medium supply manifold hole 26却媒 body discharge manifold hole 31 the gasket channel 31a passage 31b flow path 31c passage 31c1 passage 31c2 passage 32 subgasket passage 100 fuel cell stack 200 fuel cell stack 201 gas seal packing (gasket)
202 Distribution groove 203 Communication hole

Claims (12)

An electrolyte layer-electrode assembly having an electrolyte layer and a pair of electrodes sandwiching the inner part from the peripheral edge of the electrolyte layer;
A pair of annular gaskets arranged so as to sandwich a periphery of the electrolyte of the electrolyte layer-electrode assembly and surround each of the pair of electrodes;
A plate-like, reaction-fluid gas channel is formed so as to sandwich the electrolyte layer-electrode assembly and the pair of gaskets, and a reaction gas flows on one main surface in contact with the electrode. A pair of conductive separators,
A fuel cell in which at least one of the pair of gaskets is provided with a gasket channel that is communicated with the reaction gas channel and configured to allow the reaction gas to flow while being in contact with a peripheral portion of the electrolyte layer. .   The fuel cell according to claim 1, wherein the gasket channel is formed along the outer periphery of the electrode.   The fuel cell according to claim 2, wherein the gasket channel is formed so as to surround an outer periphery of the electrode.   2. The fuel cell according to claim 1, wherein the gasket channel communicates with a portion of the reaction gas channel that is downstream of a portion that contacts the electrode. On the other main surface of the separator that comes into contact with the gasket provided with the gasket flow path, a groove-shaped cooling medium flow path through which a cooling medium flows is formed.
The fuel cell according to claim 1, wherein at least a part of the upstream portion of the cooling medium flow path is provided at a peripheral edge portion of the separator.   A portion of the reaction gas flow channel provided in the separator that contacts the gasket provided with the gasket flow channel is in contact with the electrode of the serpentine formed in a serpentine shape, and a peripheral portion of the electrode. The fuel cell according to claim 1, comprising a peripheral flow path formed so as to follow.   The reaction gas channel provided in the separator that contacts the gasket provided with the gasket channel includes a first reaction gas channel through which the reaction gas flows while being in contact with the electrode, and a thickness direction of the separator 2. The fuel cell according to claim 1, further comprising: a second reaction gas channel formed so as to be joined to the gasket channel. A plurality of the reaction gas flow paths are disposed on one main surface of the separator,
A portion of the plurality of reaction gas channels that contacts the electrode (hereinafter referred to as electrode contact portion) is formed to run in parallel, and a pair of reaction gas channels positioned on the outermost side among the plurality of reaction gas channels. The fuel cell according to claim 1, wherein a downstream portion of the electrode contact portion is formed along the outer periphery of the electrode.   9. The downstream portion of the electrode contact portion of the pair of reaction gas channels positioned on the outermost side among the plurality of reaction gas channels is formed so as to surround an outer periphery of the electrode. Fuel cell. An annular subgasket is provided between the electrolyte layer-electrode assembly and the gasket,
The fuel cell according to claim 1, wherein the sub-gasket is provided with a sub-gasket channel so as to be joined to the gasket channel in a thickness direction of the separator.   The fuel cell according to claim 5, wherein a portion other than the upstream portion of the cooling fluid channel is formed in a serpentine shape.   A fuel cell stack, wherein a plurality of the fuel cells according to claim 1 are stacked and fastened.

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