JP2011258428A - Polymer electrolyte fuel cell and fuel cell stack with the same - Google Patents

Abstract

An object of the present invention is to provide a polymer electrolyte fuel cell capable of suppressing a decrease in the contact area of a separator and ensuring stable cell performance even when the position of the separator is shifted when fastening a fuel cell. And
SOLUTION: A membrane electrode assembly 5 is formed in a plate shape, and is formed in a plate shape, a conductive first separator 6A disposed so as to be in contact with a first electrode 4A of the membrane electrode assembly 5, A conductive second separator 6B disposed so as to be in contact with the second electrode 4B of the membrane electrode assembly 5, and a groove on one main surface of the first separator 6A that is in contact with the first electrode 4A. The first reaction gas flow path 8 is formed in a groove shape on one main surface of the second electrode 4B that contacts the second separator 6B so that a plurality of linear second rib portions 12 run in parallel. A polymer electrolyte fuel cell in which the second reaction gas flow path 9 is formed.
[Selection] Figure 2

Description

  The present invention relates to a configuration of a polymer electrolyte fuel cell and a fuel cell stack including the same, and more particularly to a configuration of a separator and a gas diffusion electrode of a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell (hereinafter referred to as PEFC) generates electric power and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. is there. A single cell (cell) of PEFC includes a MEA (MemBrAne-Electrode-Assembly) comprising a polymer electrolyte membrane and a pair of gas diffusion electrodes (anode and cathode), a gasket, and a conductive And a separator. In general, PEFC is used by stacking a plurality of such cells.

  By the way, one main surface of the separator is supplied with fuel gas or oxidant gas (these are called reaction gases), and manifold holes for forming exhaust manifolds (reaction gas supply manifold holes and reaction gas discharge holes) are formed. And a reaction gas flow path through which a reaction gas flows is provided on the main surface in contact with the gas diffusion electrode so as to communicate with these manifold holes. In addition, a cooling medium flow path through which a cooling medium flows is provided on the other main surface of the separator in order to control the inside of the PEFC to a predetermined temperature.

  As such a separator, a fuel cell using a metal plate is known (for example, see Patent Document 1). Here, FIG. 14 is a cross-sectional view schematically showing a schematic configuration of the fuel cell disclosed in Patent Document 1. As shown in FIG. In FIG. 14, a part of the fuel cell is omitted.

  As shown in FIG. 14, in the fuel cell 300 disclosed in Patent Document 1, convex portions 303A and 303B and concave portions 304A and 304B are provided on two metal plates by press working, respectively. Separators 301A and 301B are formed. The metal separator 301A and the metal separator 301B are arranged so that the convex portion 303A of one metal separator 301A and the convex portion 303B of the other metal separator 301B are in contact with each other.

JP 2004-207071 A

  However, in the fuel cell 300 disclosed in Patent Document 1, when the metal separators 301A and 301B are displaced in the surface direction, the contact area between the metal separators 301A and 301B decreases compared to the design value, and the fuel cell 300 May cause an increase in resistance loss. In addition, when the contact area between the metal separators 301A and 301B decreases, stress beyond the assumption is applied to the contact portions of the metal separators 301A and 301B, causing the metal separators 301A and 301B to be deformed. As a result, there is a problem that the flow path of the reaction gas and the cooling medium formed by the press molding is deformed and the fluid circulation as designed cannot be performed.

  The present invention has been made to solve the above-described problems. Even when the position of the separator is shifted when the fuel cell is fastened, the decrease in the contact area of the separator is suppressed and stable battery performance is ensured. An object of the present invention is to provide a polymer electrolyte fuel cell and a fuel cell stack including the same.

  In order to solve the above problems, a polymer electrolyte fuel cell according to the present invention includes a polymer electrolyte membrane, and a membrane electrode joint having a first electrode and a second electrode sandwiching a pair of main surfaces of the polymer electrolyte membrane. And a conductive first separator formed in a plate shape and arranged to contact the first electrode of the membrane electrode assembly, and formed in a plate shape and the second of the membrane electrode assembly. A conductive second separator disposed in contact with the electrode, and a groove-shaped first reactive gas flow path is formed on one main surface of the first separator that contacts the first electrode. In addition, a groove-like second reaction gas flow path is formed on one main surface of the second electrode that contacts the second separator.

  Thereby, even if the position of a separator shifts | deviates when fastening a fuel cell, the fall of the contact area of a separator can be suppressed.

  In the polymer electrolyte fuel cell according to the present invention, the second separator may be formed so that a central portion thereof is flat.

  In the polymer electrolyte fuel cell according to the present invention, the second upstream subgas may be communicated with the upstream surface of the second reaction gas channel on the main surface of the second separator that contacts the second electrode. A second downstream sub-gas channel may be provided so as to communicate with the channel and the downstream end of the second reaction gas channel.

  Moreover, in the polymer electrolyte fuel cell according to the present invention, the second separator has the second surface on the main surface opposite to the main surface in contact with the second electrode as viewed from the thickness direction of the second separator. Of the portion overlapping the electrode, a portion other than the second upstream sub-gas channel and the second downstream sub-gas channel may be formed to be flat.

  The polymer electrolyte fuel cell according to the present invention further includes an annular membrane reinforcing member disposed at a peripheral portion of the main surface of the polymer electrolyte membrane, and the membrane reinforcing member includes the second separator of the second separator. You may provide so that it may contact with one main surface (henceforth one main surface of a 2nd separator) which contacts 2 electrodes.

  In the polymer electrolyte fuel cell according to the present invention, a portion of the membrane reinforcing member that contacts one main surface of the second separator communicates with an upstream end of the second reaction gas channel. A second downstream sub-gas channel may be provided so as to communicate with the second upstream sub-gas channel and the downstream end of the second reactive gas channel.

  In the polymer electrolyte fuel cell according to the present invention, a portion of the membrane reinforcing member that contacts one main surface of the second separator communicates with an upstream end of the second reaction gas channel. At least one of the second downstream sub-gas channels is provided to communicate with the second upstream sub-gas channel and the downstream end of the second reaction gas channel, and is in contact with the second electrode of the second separator. The main surface includes at least a second upstream sub-gas channel and a second downstream sub-gas channel so as to communicate with an upstream end of the second reactive gas channel and a downstream end of the second reactive gas channel. The other channel may be provided.

  Moreover, in the polymer electrolyte fuel cell according to the present invention, the second separator has the second surface on the main surface opposite to the main surface in contact with the second electrode as viewed from the thickness direction of the second separator. The part overlapping with the electrode may be formed to be flat.

  In the polymer electrolyte fuel cell according to the present invention, the first reaction gas channel may be formed such that a plurality of linear first rib portions run in parallel.

  In the polymer electrolyte fuel cell according to the present invention, the first rib portion and the second rib portion may be formed so as to run in parallel with each other when viewed from the thickness direction of the second separator. .

  Furthermore, in the polymer electrolyte fuel cell of the present invention, the second electrode has a gas diffusion layer, and the gas diffusion layer has a polymer resin and conductive particles, and is formed to have air permeability. May be. Further, the second reaction gas flow path may be formed in the gas diffusion layer of the second electrode.

  In the fuel cell stack according to the present invention, a plurality of the polymer electrolyte fuel cells are stacked and fastened.

  According to the polymer electrolyte fuel cell of the present invention and the fuel cell stack including the same, even when the position of the separator is shifted when the fuel cell is fastened, the decrease in the contact area of the separator is suppressed, and stable battery performance is achieved. It can be secured.

FIG. 1 is a perspective view schematically showing a schematic configuration of a fuel cell stack according to Embodiment 1 of the present invention. 2 is a cross-sectional view schematically showing a schematic configuration of a cell stack in the fuel cell stack shown in FIG. FIG. 3 is a schematic diagram showing a schematic configuration of the cathode gas diffusion layer of the polymer electrolyte fuel cell shown in FIG. FIG. 4 is a schematic diagram showing a schematic configuration of a cathode separator of the polymer electrolyte fuel cell shown in FIG. FIG. 5 is a schematic view in which a cathode gas diffusion layer is superimposed on the cathode separator of the polymer electrolyte fuel cell shown in FIG. 2 and is seen through from the thickness direction of the cathode separator. FIG. 6 is a schematic diagram showing a schematic configuration of an anode separator of the polymer electrolyte fuel cell shown in FIG. FIG. 7 is a schematic diagram showing a schematic configuration of the cathode gas diffusion layer of the polymer electrolyte fuel cell in Modification 1 of the polymer electrolyte fuel cell according to the first embodiment. FIG. 8 is a schematic diagram showing a schematic configuration of the cathode separator of the polymer electrolyte fuel cell according to the first modification. FIG. 9 is a schematic view in which the cathode gas diffusion layer shown in FIG. 7 is superimposed on the cathode separator shown in FIG. 8 and is seen through from the thickness direction of the cathode separator. FIG. 10 is a cross-sectional view schematically showing a schematic configuration of the cell stack in the fuel cell stack according to Embodiment 2 of the present invention. FIG. 11 is a schematic diagram showing a schematic configuration of a membrane reinforcing member in the polymer electrolyte fuel cell shown in FIG. 12 is a schematic view in which the cathode gas diffusion layer shown in FIG. 3 is overlaid on the membrane reinforcing member shown in FIG. FIG. 13 is a schematic diagram showing a schematic configuration of a cathode separator in the polymer electrolyte fuel cell shown in FIG. FIG. 14 is a cross-sectional view schematically showing a schematic configuration of the fuel cell disclosed in Patent Document 1. As shown in FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, in all the drawings, only components necessary for explaining the present invention are extracted and illustrated, and other components are not illustrated. Furthermore, the present invention is not limited to the following embodiment.

(Embodiment 1)
The polymer electrolyte fuel cell and the fuel cell stack including the same according to Embodiment 1 of the present invention illustrate an aspect in which a second reaction gas channel is formed in the second electrode.
[Configuration of fuel cell stack]
FIG. 1 is a perspective view schematically showing a schematic configuration of a fuel cell stack according to Embodiment 1 of the present invention.

  As shown in FIG. 1, a fuel cell stack 100 according to Embodiment 1 of the present invention includes a polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell) 50 having a plate-like overall shape stacked in the thickness direction. The cell stack 70 formed, the end plates 61 and 62 disposed at both ends of the cell stack 70, and the end plate 61, the cell stack 70, and the end plate 62 are fastened in the stacking direction of the fuel cell 50. A fastener that is not provided. A current collecting plate and an insulating plate are disposed between the end plate 61 and the cell stack 70 and between the end plate 62 and the cell stack 70, respectively, but are not shown.

  The cell stack 70 includes a fuel gas supply manifold 131, a fuel gas discharge manifold 132, an oxidant gas supply manifold 133, and an oxidant gas discharge manifold 134 so as to penetrate the cell stack 70 in the stacking direction of the fuel cells 50. A cooling medium supply manifold 135 and a cooling medium discharge manifold 136 are provided. Each manifold is provided with appropriate piping, and fuel gas, oxidant gas, and cooling medium are supplied to the fuel cell stack 100 and discharged.

[Configuration of polymer electrolyte fuel cell]
Next, the configuration of the polymer electrolyte fuel cell according to Embodiment 1 of the present invention will be described with reference to FIG.

  FIG. 2 is a cross-sectional view schematically showing a schematic configuration of the cell stack 70 in the fuel cell stack 100 shown in FIG.

  As shown in FIG. 2, the fuel cell 50 according to the first embodiment includes an MEA (MemBrAne-Electrode-Assembly) 5, gaskets 7A, 7B, and 7C, and an anode separator (first separator). 6A and a cathode separator (second separator) 6B.

  The MEA 5 includes a polymer electrolyte membrane 1 that selectively transports hydrogen ions, an anode electrode (first electrode) 4A, and a cathode electrode (second electrode) 4B. The polymer electrolyte membrane 1 has a substantially quadrangular (here, rectangular) shape, and an anode electrode 4A and a cathode are positioned on both sides of the polymer electrolyte membrane 1 so as to be located inward from the peripheral edge thereof. Electrodes 4B are provided respectively. Note that manifold holes such as the cooling medium supply manifold hole 35 are provided in the peripheral edge portion of the polymer electrolyte membrane 1 so as to penetrate in the thickness direction.

  The anode electrode 4A is provided on one main surface of the polymer electrolyte membrane 1, and has a substantially quadrangular (here, rectangular) shape. The anode electrode 4A includes an anode catalyst layer 2A and an anode gas diffusion layer 3A provided on the anode catalyst layer 2A. The anode catalyst layer 2A includes a catalyst-supporting carbon made of carbon powder (conductive carbon particles) supporting a platinum-based metal catalyst (electrode catalyst) and a polymer electrolyte attached to the catalyst-supporting carbon. The anode gas diffusion layer 3A has both gas permeability and conductivity, and the material constituting the anode gas diffusion layer 3A is not particularly limited, and those known in the art may be used. For example, a conductive porous substrate such as carbon cloth or carbon paper can be used. In addition, the conductive porous substrate may be subjected to water repellent treatment by a conventionally known method.

  The cathode electrode 4B is provided on the other main surface of the polymer electrolyte membrane 1, and has a substantially quadrangular (here, rectangular) shape. The cathode electrode 4B includes a cathode catalyst layer 2B and a cathode gas diffusion layer 3B provided on the cathode catalyst layer 2B and having gas permeability and conductivity. In the cathode gas diffusion layer 3B), a groove-like oxidant gas flow path (second reactive gas flow path) 9 is formed on the main surface of the cathode gas diffusion layer 3B) that is in contact with the cathode separator 6B. ing. The cathode catalyst layer 2B includes a catalyst-supporting carbon made of carbon powder (conductive carbon particles) supporting a platinum-based metal catalyst (electrode catalyst) and a polymer electrolyte attached to the catalyst-supporting carbon. The detailed configuration of the oxidant gas channel 9 will be described later.

  The cathode gas diffusion layer 3B is made of a sheet having a polymer resin and conductive particles without using a carbon fiber base material impregnated with a resin used in the gas diffusion layer in the conventional fuel cell. And is formed to have air permeability.

  Examples of the conductive particle material include carbon materials such as graphite, carbon black, and activated carbon. Examples of carbon black include acetylene black (AB), furnace black, ketjen black, Vulcan, and the like. These materials may be used alone, or a plurality of materials may be used in combination. In addition, the raw material form of the carbon material may be any shape such as powder, fiber, and granule.

  In addition, as the polymer resin, PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), PVDF (polyvinylidene fluoride), ETFE (tetrafluoroethylene / ethylene copolymer), PCTFE (polychlorotrifluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) and the like can be mentioned, and PTFE is preferable from the viewpoints of heat resistance, water repellency and chemical resistance. The raw material of PTFE includes a dispersion and a powdery shape, but the dispersion is preferable from the viewpoint of workability. The polymer resin has a function as a binder that binds the conductive particles. In addition, since the polymer resin has water repellency, it also has a function (water retention) to confine water in the system inside the fuel cell 50.

  Further, the cathode gas diffusion layer 3B may contain a trace amount of a surfactant, a dispersion solvent, and the like used in manufacturing the cathode gas diffusion layer 3B in addition to the conductive particles and the polymer resin. Examples of the dispersion solvent include water, alcohols such as methanol and ethanol, and glycols such as ethylene glycol. Examples of the surfactant include nonionic compounds such as polyoxyethylene alkyl ethers and zwitterionic compounds such as alkylamine oxides. What is necessary is just to set suitably the quantity of the dispersion solvent used at the time of manufacture, and the quantity of surfactant according to the kind of electroconductive particle, the kind of polymer resin, those compounding ratios, etc. In general, as the amount of the dispersion solvent and the amount of surfactant increases, the polymer resin (fluororesin) and conductive particles (carbon) tend to be uniformly dispersed, but the fluidity tends to increase and it becomes difficult to form a sheet. There is. The cathode gas diffusion layer 3B may include materials other than the conductive particles, the polymer resin, the surfactant, and the dispersion solvent (for example, short-fiber carbon fibers).

  The cathode gas diffusion layer 3B preferably contains 5% by weight or more of a polymer resin from the viewpoint of exerting a function as a binder, so that the cathode gas diffusion layer 3B has a uniform thickness. From the viewpoint of simplifying the conditions during the rolling process, it is preferably contained at 50% by weight or less. Moreover, it is more preferable that it is contained in the quantity of 10-30 weight% from a viewpoint similar to the above.

  Here, a manufacturing method of the cathode gas diffusion layer 3B will be described.

  The cathode gas diffusion layer 3B is manufactured by kneading, extruding, rolling, and firing a mixture containing a polymer resin and conductive particles. Specifically, carbon, which is conductive particles, a dispersion solvent, and a surfactant are introduced into a stirrer / kneader, and then kneaded, pulverized, and granulated to disperse the carbon in the dispersed solvent. Next, the fluororesin, which is a polymer resin, is further dropped into a stirrer / kneader and stirred and kneaded to disperse the carbon and the fluororesin. The obtained kneaded material is rolled to form a sheet, and fired to remove the dispersion solvent and the surfactant, thereby producing a sheet for forming the cathode gas diffusion layer 3B. And the groove | channel used as the oxidant gas flow path 9 is formed in the main surface of the sheet | seat manufactured in this way by appropriate methods (for example, shaping | molding using a press machine etc., cutting using a cutting machine etc.). Thus, the cathode gas diffusion layer 3B is obtained. The surfactant can be appropriately selected depending on the material of the conductive particles (carbon material) and the type of the dispersion solvent, and the surfactant need not be used.

  The cathode gas diffusion layer 3B thus manufactured has a lower porosity than the carbon fiber base material impregnated with the resin used in the gas diffusion layer in the conventional fuel cell, but the reaction gas (oxidation gas) The agent gas) is configured to have a porosity that can move sufficiently (has sufficient air permeability). For this reason, even the cathode gas diffusion layer 3B manufactured by the above manufacturing method sufficiently fulfills the role as a gas diffusion layer. In the first embodiment, the anode gas diffusion layer 3A is made of a conductive porous substrate in the same manner as the gas diffusion layer of the conventional fuel cell. However, the present invention is not limited to this. You may employ | adopt the form comprised with the sheet | seat which has high molecular resin and electroconductive particle like the layer 3B.

  Further, around the anode electrode 4A and the cathode electrode 4B of the MEA 5, a pair of fluorine rubber doughnut-shaped gaskets 7A and 7B are disposed with the polymer electrolyte membrane 1 interposed therebetween. This prevents fuel gas and oxidant gas from leaking out of the battery, and prevents these gases from being mixed with each other in the fuel cell 50. Note that manifold holes such as a cooling medium supply manifold hole 35 formed of through-holes in the thickness direction are provided in the peripheral portions of the gaskets 7A and 7B. Further, the gaskets 7A and 7B have shapes if the fuel gas and the oxidant gas are prevented from leaking out of the battery, and these gases are prevented from being mixed with each other in the fuel cell 100. Is optional.

  Further, a conductive anode separator 6A and a cathode separator 6B are disposed so as to sandwich the MEA 5 and the gaskets 7A and 7B. Thereby, MEA 5 is mechanically fixed, and when a plurality of fuel cells 50 are stacked in the thickness direction, MEA 5 is electrically connected. In addition, these separators 6A and 6B can use the metal excellent in heat conductivity and electroconductivity, For example, what gave the surface of the plate made from titanium or stainless steel gold-plating can be used. .

  Further, a doughnut-shaped gasket 7C made of fluororubber is disposed between the adjacent anode separator 6A and cathode separator 6B. This prevents the cooling medium from leaking out of the fuel cell 50. A manifold hole such as a cooling medium supply manifold hole 35 made of a through hole in the thickness direction is provided at the peripheral edge of the gasket 7C.

  A groove-like fuel gas flow path (first reaction gas flow path) 8 through which fuel gas flows is provided on one main surface (hereinafter referred to as an inner surface) of the anode separator 6A that is in contact with the anode electrode 4A. The other main surface (hereinafter referred to as the outer surface) is provided with a groove-like cooling medium flow path 10 through which a cooling medium (for example, antifreeze such as water or ethylene glycol) flows. . Further, on one main surface (hereinafter referred to as an inner surface) that contacts the cathode electrode 4B of the cathode separator 6B, a groove shape for supplying the oxidant gas from the oxidant gas supply manifold hole 33 to the oxidant gas flow path 9 is provided. A groove-shaped downstream sub-gas channel 92 is provided for discharging the oxidant gas flowing through the upstream sub-gas channel 91 and the oxidant gas channel 9 to the oxidant gas discharge manifold hole 34 (see FIG. 4). ). In addition, the structure of the cooling medium flow path 10 is arbitrary, for example, it may be formed in a serpentine shape or may be formed in a straight shape. Further, the dew point of the fuel gas flowing through the fuel gas flow path 8 and the dew point of the oxidant gas flowing through the oxidant gas flow path 9 are lower than the temperature of the cooling medium flowing through the cooling medium flow path 10. It may be higher than the temperature of the cooling medium.

  Thereby, fuel gas and oxidant gas are supplied to the anode electrode 4A and the cathode electrode 4B, respectively, and these reaction gases react to generate electricity and heat. Further, the generated heat is recovered by passing a cooling medium such as cooling water through the cooling medium flow path 10.

  The fuel cell 50 configured in this manner may be used as a single cell (cell), or a plurality of fuel cells 50 may be stacked and used as the fuel cell stack 100. In the first embodiment, the first separator is the anode separator 6A, the second separator is the cathode separator 6B, the first reaction gas channel is the fuel gas channel 8, and the second reaction gas channel is However, the present invention is not limited to this, and the first separator is the cathode separator 6B, the second separator is the anode separator 6A, and the first reaction gas channel is the oxidant gas channel 9. The second reaction gas channel may be the fuel gas channel 8.

[Configuration of reaction gas flow path and separator]
Next, the oxidant gas flow path 9, the cathode separator 6B, and the anode separator 6A provided in the cathode gas diffusion layer 3B will be described in detail with reference to FIGS.

  FIG. 3 is a schematic diagram showing a schematic configuration of the cathode gas diffusion layer 3B of the fuel cell 50 shown in FIG. FIG. 4 is a schematic diagram showing a schematic configuration of the cathode separator 6B of the fuel cell 50 shown in FIG. FIG. 5 is a schematic view of the cathode separator 6B of the fuel cell 50 shown in FIG. 2 overlapped with the cathode gas diffusion layer 3B and seen through from the thickness direction of the cathode separator 6B. In FIG. 3, the vertical direction in the cathode gas diffusion layer 3B is represented as the vertical direction in the drawing, and in FIGS. 4 and 5, the vertical direction in the cathode separator 6B is represented as the vertical direction in the drawing. Moreover, in FIG. 5, the oxidant gas flow path 9 is shown with the virtual line (two-point difference line).

  First, the configuration of the oxidant gas flow path 9 and the cathode separator 6B provided in the cathode gas diffusion layer 3B will be described in detail with reference to FIGS.

  As shown in FIG. 3, a plurality of oxidant gas flow paths 9 are formed in a straight line on the main surface of the cathode gas diffusion layer 3B as viewed from the thickness direction of the cathode gas diffusion layer 3B. The oxidant gas flow path 9 has an upstream communication part 9a, a main gas flow path part 9b, and a downstream communication part 9c. The upstream communication portion 9a is formed such that its upstream end communicates with the upstream sub-gas flow channel 91 (see FIG. 5) and its downstream end communicates with the upstream end of the main gas flow channel portion 9b. The main gas flow path portion 9b is formed to extend linearly in the vertical direction, and its downstream end is formed to communicate with the upstream end of the downstream communication portion 9c. The downstream end of the downstream communication portion 9c is formed so as to communicate with the downstream sub-gas channel 92 (see FIG. 5). Further, the portion of the oxidant gas flow channel 9 between the main gas flow channel portion 9 b and the main gas flow channel portion 9 b forms the second rib portion 12. In the present embodiment, the main gas flow path portion 9b is provided with the stripe portion 12a so as to extend linearly in the vertical direction, and the stripe portion 12a also constitutes the second rib portion 12.

  The oxidant gas flow path 9 is formed so that a plurality of linear second rib portions 12 run in parallel. Here, the term “parallel running” means that they are provided side by side. Among the plurality of second rib portions 12, one second rib portion 12 is specified and along the specified second rib portion 12. This means that another second rib portion 12 is formed. And, “the oxidant gas flow path 9 is formed so that the plurality of linear second rib portions 12 run in parallel” means that the plurality of oxidant gas flow paths are from the upstream end to the downstream end. As a whole, it means that a plurality of oxidant gas flow paths are provided so that the flow directions of the oxidant gas flowing through the respective flow paths coincide with each other. Therefore, it is not necessary that the plurality of oxidant gas flow paths be provided in complete alignment from the upstream end to the downstream end, and the plurality of oxidant gas flow paths have portions that are not provided side by side. It may be.

  Further, as shown in FIG. 4, the cathode separator 6B is plate-shaped and is formed in a substantially quadrangular shape (here, rectangular), and each manifold hole such as the fuel gas supply manifold hole 31 is formed in the peripheral portion thereof. However, it is provided so as to penetrate in the thickness direction. Specifically, a cooling medium supply manifold hole 35 is provided in an upper portion of one side portion (hereinafter referred to as a first side portion) of the cathode separator 6B, and a fuel gas discharge manifold hole is provided in the lower portion thereof. 32 is provided. Further, an oxidant gas supply manifold hole 33 is provided inside the upper part of the cooling medium supply manifold hole 35 in the cathode separator 6B. Further, a fuel gas supply manifold hole 31 is provided in the upper part of the other side part (hereinafter referred to as the second side part) of the cathode separator 6B, and a cooling medium discharge manifold hole 36 is provided in the lower part thereof. ing. An oxidant gas discharge manifold hole 34 is provided inside the lower portion of the cooling medium discharge manifold hole 36 in the cathode separator 6B.

  As shown in FIGS. 4 and 5, a groove-shaped upstream sub-gas flow channel 91 and a groove-shaped downstream sub-gas flow channel 92 are formed on the inner surface of the cathode separator 6B so as to communicate with the oxidant gas flow channel 9. Is provided. The upstream sub-gas channel 91 has an upstream end connected to the oxidant gas supply manifold hole 33 and a downstream end connected to the oxidant gas channel 9 (on the upstream end side). The downstream sub-gas channel 92 has an upstream end communicating with the oxidant gas channel 9 (on the downstream end side), and a downstream end connected to the oxidant gas discharge manifold hole 34.

  As shown in FIGS. 2 and 4, the cathode separator 6 </ b> B is formed so that the central portion thereof is flat. Here, the central portion of the cathode separator 6B refers to the other main surface of the cathode separator 6B as viewed from the thickness direction of the cathode separator 6B. The center part of the surface. More specifically, the central portion of the cathode separator 6B refers to at least a part of a portion that overlaps the cathode electrode 4B on the other main surface of the cathode separator 6B when viewed from the thickness direction of the cathode separator 6B. In FIG. 5, the portion other than the upstream sub-gas passage 91 and the downstream sub-gas passage 92 among the portions overlapping with the cathode electrode 4B when viewed from the thickness direction of the cathode separator 6B. In addition, the term “flat” refers to a shape in which the projections and depressions are not formed macroscopically in the surface direction of the cathode separator 6B. For example, the reaction gas channel or the cooling medium channel is formed by a press or a cutting machine. This refers to a shape in which no irregularities are formed. In other words, the central portion of the cathode separator 6B is formed so as to be flat as a whole, as long as the central portion of the metal plate constituting the cathode separator 6B is flat as a whole. When the 50 is laminated and fastened, it means that it may have a warp or a deflection that can be corrected by the fastening pressure. It should be noted that a part of the central portion of the cathode separator 6B may be formed so as not to be flat as long as the effects of the present invention are achieved.

  In the present embodiment, the main gas flow path portion 9b of the oxidant gas flow path 9 is provided with one stripe portion 12a. However, the present invention is not limited to this, and a form in which the stripe portion 12a is not provided is provided. You may employ | adopt and the form which provides the some stripe part 12a may be employ | adopted.

  Next, the configuration of the anode separator 6A will be described in detail with reference to FIGS.

  FIG. 6 is a schematic diagram showing a schematic configuration of the anode separator 6A of the fuel cell 100 shown in FIG. In FIG. 6, the vertical direction in the anode separator 6A is shown as the vertical direction in the figure.

  As shown in FIG. 2, the anode separator 6 </ b> A is formed in a corrugated shape (wave shape) except for the peripheral portion thereof, and the concave portion on the inner surface of the anode separator 6 </ b> A constitutes the fuel gas flow path 8. The concave portion on the outer surface constitutes the cooling medium flow path 10.

  Further, as shown in FIG. 6, the anode separator 6A is plate-shaped and is formed into a substantially quadrangular shape (here, a rectangle), and each manifold hole such as the fuel gas supply manifold hole 31 is formed at the periphery thereof. However, it is provided so as to penetrate in the thickness direction. Since the arrangement of the manifold holes is the same as that of the cathode separator 6B, a detailed description thereof is omitted.

  On the inner surface of the anode separator 6A, a groove-like fuel gas flow path 8 is formed linearly as a whole as viewed from the thickness direction of the anode separator 6A. The fuel gas channel 8 and the oxidant gas channel 9 are configured to be a so-called parallel flow. Here, the parallel flow means that the fuel gas flow path 8 and the oxidant gas flow path 9 have a part in which the oxidant gas and the fuel gas flow so as to face each other, but from the thickness direction of the fuel cell 100. Seen, it means that the directions of the overall flow of the oxidant gas and the fuel gas from the upstream side to the downstream side are aligned with each other macroscopically (as a whole).

  The fuel gas flow path 8 includes an upstream sub gas flow path 81, a downstream sub gas flow path 83, and a main gas flow path 82 that connects the upstream sub gas flow path 81 and the downstream sub gas flow path 83. The upstream end of the upstream sub gas flow path 81 is connected to the fuel gas supply manifold hole 31 to constitute the upstream end of the fuel gas flow path 8. In addition, the downstream end of the upstream sub-gas channel 81 communicates with the upstream end of the main gas channel 82. The main gas channel 82 is formed to extend linearly in the vertical direction, and the downstream end thereof communicates with the upstream end of the downstream sub gas channel 83. Further, the downstream end of the downstream sub-gas passage 83 is connected to the fuel gas discharge manifold hole 32 and constitutes the downstream end of the fuel gas passage 8. A portion of the fuel gas channel 8 between the main gas channel 82 and the main gas channel 82 forms the first rib portion 11. In the present embodiment, the main gas channel 82 is provided with a stripe portion 11a so as to extend linearly in the vertical direction, and the stripe portion 11a also constitutes the first rib portion 11.

  And the fuel gas flow path 8 is formed so that the several linear 1st rib part 11 may run in parallel. Here, the term “parallel running” means that they are provided side by side, one of the plurality of first rib portions 11 is identified with one first rib portion 11, and along the identified first rib portion 11. This means that the other first rib portion 11 is formed. And "the fuel gas flow path 8 is formed so that the plurality of linear first rib portions 11 run in parallel" means that the plurality of communication gas flow paths constituting the fuel gas flow path are It means that the flow direction of the fuel gas flowing through the communication gas flow path is generally matched from the upstream end toward the downstream end. Therefore, it is not necessary that the plurality of communication gas flow paths be provided in complete alignment from the upstream end to the downstream end, and the plurality of communication gas flow paths have portions that are not provided side by side. Also good. In the first embodiment, the first rib portion 11 and the second rib portion 12 are formed to run side by side when viewed from the thickness direction of the cathode separator 6B.

  Then, the fuel cells 50 configured as described above are stacked to form a cell stack 70, and the fuel cell stack 100 is manufactured by sandwiching the cell stack 70 between the end plate 61 and the end plate 62. can do. At this time, in the fuel cell 50 according to the first embodiment and the fuel cell stack 100 including the fuel cell 50, the central portion of the cathode separator 6B is formed so as to be flat as a whole. A contact surface with the layer 3B can be reliably ensured, and stable battery performance can be ensured. Further, in the fuel cell 50 according to the first embodiment and the fuel cell stack 100 including the same, when the fuel cell stack 100 is fastened, the cathode gas diffusion layer 3B, the anode separator 6A, and the cathode separator 6B are displaced. As a result, it is possible to suppress a reduction in the contact area between the cathode separator 6B and the anode separator 6A and the contact area between the cathode separator 6B and the cathode gas diffusion layer 3B. It is possible to suppress supply failure such as deterioration of the distribution of the reaction gas and the cooling medium.

  Next, modifications of the fuel cell 50 according to the first embodiment and the fuel cell stack 100 including the fuel cell 50 will be described.

[Modification 1]
FIG. 7 is a schematic diagram showing a schematic configuration of the cathode gas diffusion layer of the polymer electrolyte fuel cell in Modification 1 of the polymer electrolyte fuel cell according to the first embodiment. FIG. 8 is a schematic diagram showing a schematic configuration of the cathode separator of the polymer electrolyte fuel cell of Modification 1. Further, FIG. 9 is a schematic view seen from the thickness direction of the cathode separator by superposing the cathode gas diffusion layer shown in FIG. 7 on the cathode separator shown in FIG. In FIG. 7, the vertical direction in the cathode gas diffusion layer is represented as the vertical direction in the figure, and in FIGS. 8 and 9, the vertical direction in the cathode separator is represented as the vertical direction in the figure. In FIG. 9, the oxidant gas flow path 9 is indicated by a one-point difference line, and a portion of the upstream sub-gas flow path and the downstream sub-gas flow path that overlaps the cathode electrode is indicated by a virtual line (two-point difference line).

  As shown in FIGS. 7 to 9, in the polymer electrolyte fuel cell (hereinafter referred to as fuel cell) 50 according to the first modification, the shape of the oxidant gas passage 9 formed in the cathode gas diffusion layer 3B, the cathode The shapes of the upstream sub-gas channel 91 and the downstream sub-gas channel 92 formed in the separator 6B are different from those of the fuel cell 50 according to the first embodiment.

  Specifically, as shown in FIG. 7, the oxidant gas flow path 9 is formed so as to extend linearly in the vertical direction. Further, the portion between the plurality of oxidant gas flow paths 9 constitutes the second rib portion 12.

  As shown in FIG. 8, the upstream sub-gas channel 91 has an upstream communication portion 91a formed in a crank shape and a flow dividing portion 91b formed in a U shape. The upstream end of the upstream communication portion 91 a is connected to the oxidant gas supply manifold hole 33 and constitutes the upstream end of the upstream sub-gas passage 91. Further, the downstream end of the upstream communication portion 91a is connected to the upstream end of the flow dividing portion 91b. The downstream part of the diversion part 91b is formed so as to overlap with the upstream part of the oxidant gas flow path 9 when viewed from the thickness direction of the cathode separator 6B (see FIG. 9). As a result, the oxidant gas that has flowed through the upstream sub-gas channel 91 is supplied to the oxidant gas channel 9.

  The downstream sub gas flow path 92 has a downstream communication portion 92a formed in a crank shape and a flow dividing portion 92b formed in a U shape. The upstream part of the diversion part 92b is formed so as to overlap with the downstream part of the oxidant gas flow path 9 when viewed from the thickness direction of the cathode separator 6B (see FIG. 9). The upstream end of the downstream communication portion 92a is connected to the downstream end of the flow dividing portion 92b. Further, the downstream end of the downstream communication portion 92 a is connected to the oxidant gas discharge manifold hole 34 and constitutes the downstream end of the downstream sub gas flow path 92.

  Even the fuel cell 50 and the fuel cell stack 100 including the fuel cell 50 according to the first modification configured as described above have the same effects as the fuel cell 50 and the fuel cell stack 100 according to the first embodiment.

(Embodiment 2)
The polymer electrolyte fuel cell and the fuel cell stack including the same according to the second embodiment of the present invention illustrate an aspect in which a membrane reinforcing member is provided.

[Configuration of fuel cell stack]
FIG. 10 is a cross-sectional view schematically showing a schematic configuration of the cell stack in the fuel cell stack according to Embodiment 2 of the present invention. In FIG. 10, a part of the polymer electrolyte fuel cell constituting the cell stack is developed.

  As shown in FIG. 10, the fuel cell stack 100 (polymer electrolyte fuel cell 50 (hereinafter referred to as fuel cell 50)) according to the second embodiment of the present invention is the same as the fuel cell stack 100 (fuel) according to the first embodiment. The basic structure is the same as that of the battery 50), except that the membrane reinforcing members 13A and 13B are provided at the peripheral edge of the polymer electrolyte membrane 1, and that the upstream sub-gas channel 91 and the downstream are provided in the membrane reinforcing member 13B. The difference is that the sub-gas channel 92 is formed (see FIG. 11). The fuel cell stack 100 (fuel cell 50) according to the second embodiment is different from the fuel cell stack 100 (fuel cell 50) according to the first embodiment in the shapes of the cathode separator 6B and the gaskets 7A and 7B. As the gaskets 7A and 7B, for example, a gasket formed in a continuous ring shape (a shape in which a plurality of O-rings are connected) as described in JP-A-2006-310288 may be used. The detailed explanation is omitted.

  Specifically, the membrane reinforcing member 13A is disposed on one main surface of the polymer electrolyte membrane 1 (main surface on which the anode electrode 4A is disposed). A membrane reinforcing member 13B is disposed on the other main surface of the polymer electrolyte membrane 1 (main surface on which the cathode electrode 4B is disposed). Here, the shape of the membrane reinforcing member 13B will be described in detail with reference to FIGS. The shape of the membrane reinforcing member 13A is basically the same as the shape of the membrane reinforcing member 13B except that the upstream subgas channel 91 and the downstream subgas channel 92 are not formed. Is omitted.

  FIG. 11 is a schematic diagram showing a schematic configuration of the membrane reinforcing member 13B in the fuel cell 50 shown in FIG. 12 is a schematic view in which the cathode gas diffusion layer 3B shown in FIG. 3 is overlaid on the membrane reinforcing member 13B shown in FIG. 11 and 12, the vertical direction of the membrane reinforcing member 13B is shown as the vertical direction in the drawings.

  As shown in FIGS. 11 and 12, the membrane reinforcing member 13 </ b> B is formed in a rectangular shape similar to the polymer electrolyte membrane 1, and the outer peripheral surface thereof is flush with the outer peripheral surface of the polymer electrolyte membrane 1. It is formed (see FIG. 10). An opening 14 is provided in the main surface of the membrane reinforcing member 13B. The opening 14 is formed in the same size (or slightly larger than that) as the main surface of the cathode gas diffusion layer 3B (see FIG. 10). That is, the membrane reinforcing member 13B is formed in an annular shape.

  In addition, manifold holes such as the fuel gas supply manifold hole 31 are provided on the main surface of the membrane reinforcing member 13B. The position of each manifold hole such as the fuel gas supply manifold hole 31 is the same as that of each manifold hole such as the fuel gas supply manifold hole 31 provided in the cathode separator 6B, and thus detailed description thereof is omitted.

  Further, an upstream sub-gas channel 91 and a downstream sub-gas channel 92 are formed on one main surface of the membrane reinforcing member 13B that contacts the cathode separator 6B. The upstream end of the upstream sub-gas passage 91 is connected to the oxidant gas supply manifold hole 33. Further, the downstream end of the upstream sub-gas channel 91 is connected to the opening 14 and, as shown in FIG. 12, the upstream communication portion 9a of the oxidant gas channel 9 (upstream end of the oxidant gas channel 9). It is formed so as to communicate. On the other hand, the upstream end of the downstream sub-gas channel 92 is connected to the opening 14 and is formed to communicate with the downstream communication portion 9c (downstream end of the oxidizing gas channel 9) as shown in FIG. Yes. Further, the downstream end of the downstream sub-gas channel 92 is connected to the oxidant gas discharge manifold hole 34.

  Next, the shape of the cathode separator 6B will be described with reference to FIG.

  FIG. 13 is a schematic diagram showing a schematic configuration of the cathode separator 6B in the fuel cell 50 shown in FIG. In FIG. 13, the vertical direction of the cathode separator 6B is represented as the vertical direction in the figure.

  As shown in FIG. 13, in the fuel cell stack 100 (fuel cell 50) according to the second embodiment, the other side of the cathode separator 6B as viewed from the thickness direction of the cathode separator 6B, which is the central portion of the cathode separator 6B. A portion overlapping the cathode electrode 4B on the main surface is formed to be flat.

  Even the fuel cell stack 100 (fuel cell 50) according to the second embodiment configured as described above has the same effects as the fuel cell stack 100 (fuel cell 50) according to the first embodiment.

  In the second embodiment, a form in which both the upstream sub-gas channel 91 and the downstream sub-gas channel 92 are formed on one main surface of the membrane reinforcing member 13B is not limited to this. For example, Alternatively, a form in which the upstream sub-gas channel 91 is formed on one main surface of the membrane reinforcing member 13B and the downstream sub-gas channel 92 is formed on the inner surface of the cathode separator 6B may be adopted. Further, for example, a form in which the downstream sub-gas channel 92 is formed on one main surface of the membrane reinforcing member 13B and the upstream sub-gas channel 91 is formed on the inner surface of the cathode separator 6B may be adopted. That is, at least one of the upstream sub-gas channel 91 and the downstream sub-gas channel 92 is formed on one main surface of the membrane reinforcing member 13B, and the upstream sub-gas channel 91 and the downstream sub-gas flow are formed on the inner surface of the cathode separator 6B. A form in which at least the other flow path of the path 92 is formed may be employed.

  When at least the other of the upstream sub-gas passage 91 and the downstream sub-gas passage 92 is formed on the inner surface of the cathode separator 6B, the central portion of the cathode separator 6B extends from the thickness direction of the cathode separator 6B. As seen, the portion of the other main surface of the cathode separator 6B that overlaps the cathode electrode 4B is a portion other than the portion where the upstream sub-gas passage 91 and / or the downstream sub-gas passage 92 are formed.

  Further, the upstream sub-gas channel 91 and / or the downstream sub-gas channel 92 formed on the inner surface of the cathode separator 6B may have any shape as long as it is formed to communicate with the oxidant gas channel 9. For example, the shape described in the first embodiment may be used, or the shape described in the first modification may be used.

  In the above-described embodiment (including modifications), the fuel gas flow path 8 and the oxidant gas flow path 9 are formed in a so-called straight shape. However, the present invention is not limited to this, and the fuel gas flow path 8 includes a plurality of fuel gas flow paths 8. As long as the linear first rib portions 11 are formed so as to run parallel to each other, any shape may be used, for example, a serpentine shape may be used. Similarly, the oxidant gas flow path 9 may have any shape as long as the plurality of linear second rib portions 12 are formed so as to run in parallel with each other, for example, a serpentine shape. May be.

  The polymer electrolyte fuel cell and the fuel cell stack of the present invention can suppress a decrease in the contact area of the separator even when the position of the separator is shifted when fastening the fuel cell, and can ensure stable battery performance. The polymer electrolyte fuel cell and the fuel cell stack are useful in the field of fuel cells.

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2A Anode catalyst layer 2B Cathode catalyst layer 3A Anode gas diffusion layer 3B Cathode gas diffusion layer 4A Anode electrode (1st electrode)
4B Cathode electrode (second electrode)
5 MEA (MemBrAne-Electrode-Assembly: membrane electrode assembly)
6A Anode separator (first separator)
6B Cathode separator (second separator)
7A Gasket 7B Gasket 7C Gasket 8 Fuel gas flow path (first reaction gas flow path)
9 Oxidant gas channel (second reactive gas channel)
9a Upstream communication section 9b Main gas flow path section 9c Downstream communication section 10 Cooling medium flow path 11 First rib section 11a Striped section (first rib section)
12 2nd rib part 12a Stripe part (2nd rib part)
31 Fuel gas supply manifold hole 32 Fuel gas discharge manifold hole 33 Oxidant gas supply manifold hole 34 Oxidant gas discharge manifold hole 35 Coolant supply manifold hole 36 Coolant discharge manifold hole 50 Fuel cell 61 End plate 62 End plate 70 Cell stack Body 81 Upstream sub-gas channel 82 Main gas channel 83 Downstream sub-gas channel 91 Upstream sub-gas channel 92 Downstream sub-gas channel 100 Fuel cell stack 131 Fuel gas supply manifold 132 Fuel gas discharge manifold 133 Oxidant gas supply manifold 134 Oxidant gas Discharge manifold 135 Cooling medium supply manifold 136 Cooling medium discharge manifold 300 Fuel cell 301A Metal separator 301B Metal separator 303A Convex part 303B Convex part 304A Concave part

Claims (12)

A membrane electrode assembly having a polymer electrolyte membrane, and a first electrode and a second electrode sandwiching a pair of main surfaces of the polymer electrolyte membrane;
A conductive first separator formed in a plate shape and disposed so as to be in contact with the first electrode of the membrane electrode assembly;
A conductive second separator formed in a plate shape and disposed so as to be in contact with the second electrode of the membrane electrode assembly,
A groove-shaped first reactive gas flow path is formed on one main surface of the first separator that contacts the first electrode,
A polymer electrolyte fuel cell, wherein a groove-like second reactive gas flow path is formed on one main surface of the second electrode that contacts the second separator.   The polymer electrolyte fuel cell according to claim 1, wherein the second separator is formed so that a central portion thereof is flat.   The main surface of the second separator that contacts the second electrode has a second upstream sub-gas channel and a downstream end of the second reactive gas channel so as to communicate with the upstream end of the second reactive gas channel. The polymer electrolyte fuel cell according to claim 1 or 2, wherein a second downstream sub-gas channel is provided so as to communicate with each other.   The second separator includes the second upstream sub-gas flow path in a portion overlapping the second electrode on the main surface opposite to the main surface in contact with the second electrode when viewed from the thickness direction of the second separator. 4. The polymer electrolyte fuel cell according to claim 3, wherein portions other than the second downstream sub-gas flow path are formed to be flat. 5. An annular membrane reinforcing member disposed at the peripheral edge of the main surface of the polymer electrolyte membrane;
The said membrane reinforcement member is provided so that it may contact with one main surface (henceforth one main surface of a 2nd separator) which contacts the said 2nd electrode of the said 2nd separator. The polymer electrolyte fuel cell as described.   A portion of the membrane reinforcing member that contacts one main surface of the second separator communicates with an upstream end of the second reactive gas flow channel, and a second upstream sub-gas flow channel and the second reactive gas flow channel. The polymer electrolyte fuel cell according to claim 5, wherein a second downstream sub-gas channel is provided so as to communicate with the downstream end of the fuel cell. A portion of the membrane reinforcing member that contacts one main surface of the second separator communicates with an upstream end of the second reactive gas flow channel, and a second upstream sub-gas flow channel and the second reactive gas flow channel. At least one flow path of the second downstream sub-gas flow path is provided so as to communicate with the downstream end of
The main surface of the second separator that contacts the second electrode has a second upstream sub-gas channel and a downstream end of the second reactive gas channel so as to communicate with the upstream end of the second reactive gas channel. The polymer electrolyte fuel cell according to claim 5, wherein at least the other flow path of the second downstream sub-gas flow path is provided so as to communicate with each other.   The second separator is formed so that a portion overlapping the second electrode on the main surface opposite to the main surface in contact with the second electrode is flat when viewed from the thickness direction of the second separator. The polymer electrolyte fuel cell according to claim 6.   2. The polymer electrolyte fuel cell according to claim 1, wherein the first reaction gas channel is formed such that a plurality of linear first rib portions run in parallel.   10. The polymer electrolyte fuel cell according to claim 9, wherein the first rib portion and the second rib portion are formed so as to run in parallel with each other when viewed from the thickness direction of the second separator. The second electrode has a gas diffusion layer;
2. The polymer electrolyte fuel cell according to claim 1, wherein the gas diffusion layer has a polymer resin and conductive particles and is formed to have air permeability. A fuel cell stack in which a plurality of polymer electrolyte fuel cells according to claim 1 are stacked and fastened.

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