JP2013114843A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell that prevents accumulation of deterioration-accelerating substances at ends of electrode catalyst layers with a simple and economical configuration and that effectively prevents deterioration of a solid polymer electrolyte membrane and the like.SOLUTION: In a fuel cell 10, a membrane electrode assembly 12, an anode separator 14, and a cathode separator 16 are laminated. On two respective sides of a solid polymer electrolyte membrane 24, the membrane electrode assembly 12 has an anode electrode 26, and a cathode electrode 28, each with a smaller surface area than that of the solid polymer electrolyte membrane 24. In the anode separator 14, a fuel gas flow passage 34 is formed so as to face the anode electrode 26. The fuel gas flow passage 34 has outer passage grooves 34a and inner passage grooves 34b. The outer passage grooves 34a are set to be larger in cross section area than the inner passage grooves 34b. And an outer peripheral edge of an electrode catalyst layer 26a comprising the anode electrode 26 is arranged to face the outer passage grooves 34a.

Description

  The present invention includes an electrolyte membrane / electrode structure provided with electrodes each having an electrode catalyst layer and a gas diffusion layer on both sides of a solid polymer electrolyte membrane, and a separator, and the separator includes the electrode It is related with the fuel cell by which the reaction gas flow path which distribute | circulates reaction gas along an electrode surface direction is formed facing.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. This fuel cell has an electrolyte membrane / electrode structure in which an anode electrode and a cathode electrode each made of an electrode catalyst (electrode catalyst layer) and porous carbon (gas diffusion layer) are disposed on both sides of a solid polymer electrolyte membrane ( A power generation cell is formed in which the MEA is sandwiched between separators (bipolar plates). Normally, in a fuel cell, a fuel cell stack in which a predetermined number of power generation cells are stacked is used as, for example, an in-vehicle fuel cell stack.

  In general, in an electrolyte membrane / electrode structure, the anode electrode and the cathode electrode have a smaller surface area than the solid polymer electrolyte membrane, and the outer peripheral edge of the solid polymer electrolyte membrane is the anode electrode and the cathode. It is exposed to the outside from the outer periphery of the electrode. Furthermore, in the anode electrode and the cathode electrode, the electrode catalyst layer may be set to have a smaller surface area than the gas diffusion layer.

  Therefore, a space is formed around the end portion of the electrode catalyst layer by the solid polymer electrolyte membrane and the inside of the gas diffusion layer, and the cathode is formed in the space during power generation (electrochemical reaction). Water generated in the electrode tends to stay. Furthermore, hydrogen peroxide generated by the reaction of oxygen and hydrogen easily accumulates in the space, and this hydrogen peroxide decomposes on the carbon carrier and platinum (Pt) in the electrode, for example, a hydroxy radical. (.OH) is generated. Thereby, the edge part of a solid polymer electrolyte membrane deteriorates, and there exists a problem that while the durability of the said solid polymer electrolyte membrane becomes easy to fall, electric power generation efficiency falls.

  Thus, for example, a fuel cell membrane-electrode assembly disclosed in Patent Document 1 is known. This membrane-electrode assembly for a fuel cell is composed of a pair of electrodes composed of a fuel electrode supplied with fuel gas and an oxygen electrode supplied with oxidant gas, and a polymer sandwiched between the pair of electrodes. An electrolyte membrane. The electrode is composed of a catalyst layer and a diffusion layer bonded to the polymer electrolyte membrane, and in the diffusion layer, the peroxide decomposing agent has a higher concentration with respect to the vicinity of the end portion in the cell surface direction than the end portion. Exists.

  As a result, the peroxide decomposing agent is present at a higher concentration than the end portion in the vicinity of the cell surface direction end portion in the diffusion layer. The peroxide can be efficiently removed from the cell. For this reason, it is said that it becomes possible to obtain the fuel cell which suppressed deterioration of the electrolyte in an electrolyte membrane or an electrode catalyst layer, and improved durability.

JP 2008-98006 A

  By the way, in said patent document 1, after apply | coating and drying a cerium solution as a peroxide decomposition agent to the edge part of a diffusion layer, the membrane-electrode assembly for fuel cells is produced. For this reason, the whole manufacturing operation of the fuel cell membrane-electrode assembly is considerably complicated, and there is a problem that an efficient and economical manufacturing operation is not performed.

  The present invention solves this type of problem, and with a simple and economical structure, prevents the deterioration promoting substance from staying at the end of the electrode catalyst layer, thereby degrading the solid polymer electrolyte membrane and the like. An object of the present invention is to provide a fuel cell that can be effectively suppressed.

  The present invention includes an electrolyte membrane / electrode structure provided with electrodes each having an electrode catalyst layer and a gas diffusion layer on both sides of a solid polymer electrolyte membrane, and a separator, and the separator includes the electrode And a fuel cell in which a reaction gas flow channel for allowing a reaction gas to flow along the electrode surface direction is formed.

  In this fuel cell, the reaction gas channel includes a plurality of channel grooves. And the cross-sectional area of the outer flow channel facing the outer periphery of the electrode is set larger than the cross-sectional area of the inner flow channel facing the other part of the electrode, and the outer peripheral end of the electrode catalyst layer is It arrange | positions facing the said outside channel groove.

  In this fuel cell, the electrode includes an anode electrode and a cathode electrode, and an outer peripheral end portion of the anode electrode catalyst layer constituting the anode electrode, and an outer peripheral end portion of the cathode electrode catalyst layer constituting the cathode electrode Is disposed offset with respect to the stacking direction of the electrolyte membrane / electrode structure and the separator, while the reaction gas flow path has a fuel gas flow path and an oxidant gas flow path, and the anode The outer peripheral end of the electrode catalyst layer faces the outer flow channel of the fuel gas flow channel, and the outer peripheral end of the cathode electrode catalyst layer is in the outer flow channel of the oxidant gas flow channel. It is preferable to oppose.

  Furthermore, in this fuel cell, it is preferable that the outer flow path groove is constituted by a separator convex portion and a seal member.

  According to the present invention, the outer peripheral end of the electrode catalyst layer is opposed to the outer channel groove set to have a larger cross-sectional area than the inner channel groove facing the other part of the electrode with respect to the reactive gas channel. Are arranged. For this reason, it is possible to satisfactorily prevent the deterioration promoting substance from staying at the outer peripheral end of the electrode catalyst layer where deterioration tends to concentrate.

  Moreover, since the cross-sectional area of the outer flow channel is set larger than the cross-sectional area of the inner flow channel, the flow rate of the reaction gas flowing through the outer flow channel can be increased. Accordingly, it is possible to more reliably prevent the deterioration promoting substance from staying, and to effectively absorb the misalignment between the electrolyte membrane / electrode structure and the separator.

  This makes it possible to effectively suppress deterioration of the solid polymer electrolyte membrane and the like with a simple and economical configuration.

It is a principal part disassembled perspective view of the fuel cell which concerns on the 1st Embodiment of this invention. It is the II-II sectional view taken on the line of the said fuel cell in FIG. It is front explanatory drawing of the anode side separator which comprises the said fuel cell. It is front explanatory drawing of the cathode side separator which comprises the said fuel cell. FIG. 3 is an explanatory diagram of a flow path before starting the fuel cell. It is explanatory drawing of the gas replacement state at the time of starting of the said fuel cell. It is a schematic cross-sectional explanatory drawing of the fuel cell which concerns on the 2nd Embodiment of this invention. It is a schematic sectional explanatory drawing of the fuel cell which concerns on the 3rd Embodiment of this invention. It is a schematic sectional explanatory drawing of the fuel cell which concerns on the 4th Embodiment of this invention. It is a principal part disassembled perspective view of the fuel cell which concerns on the 5th Embodiment of this invention. It is front explanatory drawing of the cathode side separator which comprises the said fuel cell. It is principal part sectional explanatory drawing of the fuel cell which concerns on the 6th Embodiment of this invention. It is the XIII-XIII sectional view taken on the line of the said fuel cell in FIG. It is front explanatory drawing of the cathode side separator which comprises the said fuel cell.

  As shown in FIGS. 1 and 2, the fuel cell 10 according to the first embodiment of the present invention has an electrolyte membrane / electrode structure 12 sandwiched between an anode side separator 14 and a cathode side separator 16, and is in a standing posture. Are stacked in the direction of arrow A (for example, in the horizontal direction). By stacking the plurality of fuel cells 10 in the direction of arrow A, for example, an in-vehicle fuel cell stack is configured. In addition, as the anode side separator 14 and the cathode side separator 16, for example, a carbon separator is used, but a metal separator may be used instead.

  The fuel cell 10 has a horizontally long shape, and an oxidant gas, for example, an oxygen-containing gas is supplied to one end edge in the arrow B direction (horizontal direction) in communication with each other in the arrow A direction that is the stacking direction. An oxidant gas inlet communication hole 18a for discharging, a cooling medium outlet communication hole 20b for discharging a cooling medium, and a fuel gas outlet communication hole 22b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided in the direction of arrow C ( Are arranged in the vertical direction).

  The other end edge in the direction of arrow B of the fuel cell 10 communicates with each other in the direction of arrow A, a fuel gas inlet communication hole 22a for supplying fuel gas, and a cooling medium inlet communication hole for supplying a cooling medium. 20a and an oxidant gas outlet communication hole 18b for discharging the oxidant gas are arranged in the direction of arrow C.

  The electrolyte membrane / electrode structure 12 has a horizontally long shape, for example, a solid polymer electrolyte membrane 24 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode electrode 26 sandwiching the solid polymer electrolyte membrane 24. And a cathode electrode 28. The outer dimensions of the solid polymer electrolyte membrane 24 are set larger than the outer dimensions of the anode electrode 26 and the cathode electrode 28.

  The solid polymer electrolyte membrane 24 uses an HC (hydrocarbon) electrolyte in addition to a fluorine electrolyte. For example, the solid polymer electrolyte membrane 24 may have a structure in which the main chain has a polyphenylene structure and a side chain having a sulfonic acid group.

  As shown in FIG. 2, the anode electrode 26 is an electrode catalyst formed by uniformly applying porous carbon particles having a platinum alloy supported on the surface thereof to the surface of the solid polymer electrolyte membrane 24, as will be described later. A layer (anode electrode catalyst layer) 26a and a gas diffusion layer 26b made of carbon paper or the like. Similarly, the cathode electrode 28 has an electrode catalyst layer (cathode electrode catalyst layer) 28a formed by uniformly applying porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the solid polymer electrolyte membrane 24; A gas diffusion layer 28b made of carbon paper or the like.

  The surface areas of the electrode catalyst layers 26a and 28a are set smaller than the surface areas of the gas diffusion layers 26b and 28b. The end positions of the electrode catalyst layers 26a and 28a are arranged inwardly of the end positions of the gas diffusion layers 26b and 28b.

  The solid polymer electrolyte membrane 24 is provided with protective sheet members 30a and 30b on the outer peripheral edge protruding outward from the end positions of the gas diffusion layers 26b and 28b. The protective sheet members 30a and 30b are made of a gas-impermeable material such as a film made of PEN (polyethylene naphthalate), for example. It is possible to prevent the end of the solid polymer electrolyte membrane 24 from being damaged by hydrogen peroxide.

  As shown in FIG. 3, a fuel gas flow path 34 communicating with the fuel gas inlet communication hole 22a and the fuel gas outlet communication hole 22b is formed on the surface 14a of the anode separator 14 facing the electrolyte membrane / electrode structure 12, It snakes in the direction of arrow B and is provided in the direction of arrow C. The fuel gas channel 34 is positioned between two outer channel grooves 34a facing the outer periphery of the electrode catalyst layer 26a constituting the anode electrode 26 and the outer channel groove 34a, and the outer periphery of the electrode catalyst layer 26a. And a plurality of inner flow channel grooves 34b facing the other portions.

  As shown in FIGS. 2 and 3, the cross-sectional area of the outer flow path groove 34a is set larger than the cross-sectional area of the inner flow path groove 34b. Specifically, the groove width L1 of the outer channel groove 34a is set to be longer than the groove width L2 of the inner channel groove 34b (L1> L2). The groove depth of the outer channel groove 34a is the same as the groove depth of the inner channel groove 34b. The outer peripheral end portion of the electrode catalyst layer 26a is disposed to face the outer flow path groove 34a.

  As shown in FIG. 4, on the surface 16a of the cathode side separator 16 facing the electrolyte membrane / electrode structure 12, an oxidant gas flow path communicating with the oxidant gas inlet communication hole 18a and the oxidant gas outlet communication hole 18b. 36 is provided in a direction meandering in the direction of arrow C while meandering in the direction of arrow B. The oxidant gas flow path 36 is located between the two outer flow path grooves 36a facing the outer periphery of the electrode catalyst layer 28a constituting the cathode electrode 28, and the outer flow path groove 36a. And a plurality of inner flow channel grooves 36b facing portions other than the outer periphery.

  As shown in FIGS. 2 and 4, the cross-sectional area of the outer flow path groove 36a is set larger than the cross-sectional area of the inner flow path groove 36b. Specifically, the groove width L3 of the outer flow path groove 36a is set longer than the groove width L4 of the inner flow path groove 36b (L3> L4). The groove depth of the outer channel groove 36a is the same as the groove depth of the inner channel groove 36b. The outer peripheral end portion of the electrode catalyst layer 28a is disposed so as to face the outer flow path groove 36a.

  As shown in FIGS. 1 and 2, a cooling medium flow path 38 that communicates with the cooling medium inlet communication hole 20 a and the cooling medium outlet communication hole 20 b is provided on the surface 16 b of the cathode-side separator 16. The cooling medium flow path 38 causes the cooling medium to flow in the direction of arrow B.

  On the surfaces 14a and 14b of the anode side separator 14, a first seal member 40 is provided integrally or individually around the outer peripheral edge of the anode side separator 14 (see FIGS. 1 to 3). On the surfaces 16a and 16b of the cathode-side separator 16, a second seal member 42 is provided integrally or individually around the outer peripheral edge of the cathode-side separator 16 (see FIGS. 1, 2, and 4).

  The first seal member 40 and the second seal member 42 are, for example, EPDM, NBR, fluorine rubber, silicon rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, or a cushioning material. Or use packing material.

  The operation of the fuel cell 10 configured as described above will be described below.

  As shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 18a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 22a. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet communication hole 20a.

  As shown in FIG. 4, the oxidant gas is introduced into the oxidant gas flow path 36 of the cathode side separator 16 from the oxidant gas inlet communication hole 18 a. The oxidant gas meanders in the direction of arrow C along the outer flow path groove 36a and the inner flow path groove 36b, which are a plurality of flow path grooves constituting the oxidant gas flow path 36, while folding back in the direction of arrow B. It circulates toward. Therefore, the oxidant gas moves along the cathode electrode 28 of the electrolyte membrane / electrode structure 12 (see FIGS. 1 and 2).

  On the other hand, as shown in FIG. 3, the fuel gas is introduced into the fuel gas flow path 34 of the anode-side separator 14 from the fuel gas inlet communication hole 22a. In this fuel gas flow path 34, the fuel gas snakes along the outer flow path groove 34a and the inner flow path groove 34b, which are a plurality of flow path grooves, and circulates in the arrow C direction to flow in the arrow C direction. To do. Accordingly, the fuel gas moves along the anode electrode 26 of the electrolyte membrane / electrode structure 12 (see FIGS. 1 and 2).

  Thereby, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode electrode 28 and the fuel gas supplied to the anode electrode 26 are consumed by the electrochemical reaction in the electrode catalyst layers 28a and 26a. Power generation is performed.

  Next, the oxidant gas supplied and consumed to the cathode electrode 28 is discharged to the oxidant gas outlet communication hole 18b. Similarly, the fuel gas consumed by being supplied to the anode electrode 26 is discharged to the fuel gas outlet communication hole 22b.

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 20 a is introduced into a cooling medium flow path 38 formed between the anode side separator 14 and the cathode side separator 16. The cooling medium moves in the direction of arrow B along the cooling medium flow path 38, cools the entire power generation surface of the electrolyte membrane / electrode structure 12, and then is discharged to the cooling medium outlet communication hole 20b.

  In this case, in the first embodiment, as shown in FIG. 2, the cross-sectional area of the outer flow path groove 34a constituting the fuel gas flow path 34 is set larger than the cross-sectional area of the inner flow path groove 34b. The outer peripheral end portion of the electrode catalyst layer 26a constituting the anode electrode 26 is disposed to face the outer flow path groove 34a. For this reason, the flow rate of the fuel gas in the outer flow path groove 34a is larger than the flow rate of the fuel gas in the inner flow path groove 34b, and deteriorates at the outer peripheral end of the electrode catalyst layer 26a where deterioration tends to concentrate. It is possible to reliably prevent the accelerating substance from staying.

  Similarly, the outer cross-sectional area of the outer flow path groove 36a constituting the oxidant gas flow path 36 is set larger than the cross-sectional area of the inner flow path groove 36b, and the outer periphery of the electrode catalyst layer 28a constituting the cathode electrode 28 is set. The end portion is disposed to face the outer flow path groove 36a. Therefore, the flow rate of the oxidant gas in the outer flow path groove 36a is larger than the flow rate of the oxidant gas in the inner flow path groove 36b, and at the outer peripheral end of the electrode catalyst layer 28a where deterioration tends to concentrate. It is possible to reliably prevent the deterioration promoting substance from staying.

  Moreover, since the cross-sectional areas of the outer flow path grooves 34a and 36a are set larger than the cross-sectional areas of the inner flow path grooves 34b and 36b, the flow rates of the fuel gas and the oxidant gas can be increased. As a result, the retention of the deterioration promoting substance can be more reliably prevented, and the displacement of the electrolyte membrane / electrode structure 12 from the anode side separator 14 and the cathode side separator 16 can be effectively absorbed. For this reason, the effect that it becomes possible to suppress effectively deterioration of the solid polymer electrolyte membrane 24 grade | etc., With a simple and economical structure is acquired.

  Further, in the first embodiment, when gas replacement is performed when the fuel cell 10 is started, deterioration of the outer peripheral ends of the electrode catalyst layers 26a and 28a can be satisfactorily suppressed. Specifically, as shown in FIG. 5, when the fuel cell 10 is stopped, the fuel gas passage 34 and the oxidant gas passage 36 are filled with an oxidant gas (air).

  And when starting the fuel cell 10, the process which replaces the fuel gas flow path 34 from oxidant gas to fuel gas (hydrogen gas) first is performed. Here, when the fuel gas is supplied to the fuel gas passage 34, as shown in FIG. 6, in the gas diffusion layer 26b constituting the anode electrode 26, the inner passage groove 34b and the outer passage groove 34a are opposed to each other. The oxidant gas present at the site replaces the fuel gas.

  On the other hand, the oxidant gas is a fuel gas at a portion of the gas diffusion layer 26b facing the peak portion of the anode separator 14 (between the inner channel groove 34b and between the inner channel groove 34b and the outer channel groove 34a). It is difficult to replace with. Accordingly, the portion facing the peak is at a high potential, and carbon corrosion is likely to occur.

  At that time, particularly in the portion corresponding to the outer peripheral end of the electrode catalyst layer 26a, the replacement of the fuel gas is satisfactorily performed facing the outer flow path groove 34a. Thereby, deterioration at the outer peripheral end of the electrode catalyst layer 26a can be reliably suppressed. Thereafter, the fuel gas is also replaced at the portion facing the peak portion, and the fuel cell 10 is started.

  FIG. 7 is a schematic cross-sectional explanatory view of a fuel cell 50 according to the second embodiment of the present invention. The same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third and subsequent embodiments described below, detailed description thereof is omitted.

  The fuel cell 50 sandwiches an electrolyte membrane / electrode structure 52 between the anode side separator 14 and the cathode side separator 16. The electrolyte membrane / electrode structure 52 sandwiches the solid polymer electrolyte membrane 24 between the anode electrode 54 and the cathode electrode 56. The electrode catalyst layer 26 a S constituting the anode electrode 54 is set to have a smaller surface area than the electrode catalyst layer 28 a L constituting the cathode electrode 56.

  The outer peripheral end of the electrode catalyst layer 26aS is disposed opposite to the outer flow path groove 34a constituting the fuel gas flow path 34, and the outer peripheral end of the electrode catalyst layer 28aL passes through the oxidant gas flow path 36. It arrange | positions facing the outer side flow-path groove | channel 36a which comprises.

  In the second embodiment configured as described above, the outer peripheral end portions of the electrode catalyst layers 26aS and 28aL whose outer peripheral end positions are different in the stacking direction are arranged to face the outer flow channel grooves 34a and 36a. ing. Thereby, it is possible to prevent the deteriorating substances from staying at the outer peripheral ends of the electrode catalyst layers 26aS and 28aL, and to effectively suppress the deterioration of the solid polymer electrolyte membrane 24 and the like with a simple and economical configuration. The same effects as those of the first embodiment can be obtained.

  FIG. 8 is a schematic cross-sectional explanatory view of a fuel cell 60 according to the third embodiment of the present invention.

  The fuel cell 60 sandwiches the electrolyte membrane / electrode structure 62 between the anode side separator 14 and the cathode side separator 16. The electrolyte membrane / electrode structure 62 sandwiches the solid polymer electrolyte membrane 24 between an anode electrode 64 and a cathode electrode 66. The electrode catalyst layer 26aL constituting the anode electrode 64 has a larger surface area than the electrode catalyst layer 28aS constituting the cathode electrode 66.

  The outer peripheral end of the electrode catalyst layer 26aL is disposed opposite to the outer flow channel groove 34a constituting the fuel gas flow channel 34, and the outer peripheral end of the electrode catalyst layer 28aS passes through the oxidant gas flow channel 36. It arrange | positions facing the outer side flow-path groove | channel 36a which comprises.

  In the third embodiment configured as described above, the outer peripheral end portions of the electrode catalyst layers 26aL and 28aS whose outer peripheral end portions are different in the stacking direction are disposed opposite to the outer flow channel grooves 34a and 36a. ing. Thereby, it is possible to prevent the deteriorating substances from staying at the outer peripheral ends of the electrode catalyst layers 26aL and 28aS, and to effectively suppress the deterioration of the solid polymer electrolyte membrane 24 and the like with a simple and economical configuration. The same effects as those of the first and second embodiments can be obtained.

  FIG. 9 is a schematic cross-sectional explanatory view of a fuel cell 70 according to the fourth embodiment of the present invention.

  The fuel cell 70 sandwiches the electrolyte membrane / electrode structure 12 between the anode side separator 72 and the cathode side separator 74. The anode-side separator 72 has an outer channel groove 34aL that is wide in the direction of arrow C and an inner channel groove 34b that is narrow in the direction of arrow C, while the cathode-side separator 74 is wider than the outer channel groove 36aL that is wide in the direction of arrow C. And a narrow inner channel groove 36b.

  In the range of the outer flow path groove 34aL, the electrode catalyst layer 26a of the anode electrode 26 is disposed, and the first seal member 40 is disposed. The electrode catalyst layer 28a of the cathode electrode 28 and the second seal member 42 are arranged in the range of the outer flow path groove 36aL.

  Therefore, in the fourth embodiment, the deterioration of the solid polymer electrolyte membrane 24 and the like can be effectively suppressed with a simple and economical configuration, and the like, as in the first to third embodiments. The effect is obtained.

  FIG. 10 is an exploded perspective view of main parts of a fuel cell 80 according to the fifth embodiment of the present invention.

  The fuel cell 80 includes an electrolyte membrane / electrode structure 82, an anode side separator 84, and a cathode side separator 86. As the electrolyte membrane / electrode structure 82, for example, any of the above-described electrolyte membrane / electrode structures 12, 52, or 62 may be used. The anode side separator 84 and the cathode side separator 86 are constituted by, for example, a carbon separator.

  A fuel gas flow path 88 extending in the direction of arrow B is provided on a surface 84 a of the anode separator 84 facing the electrolyte membrane / electrode structure 82. The fuel gas flow path 88 is positioned between the two outer flow path grooves 88a facing the upper and lower sides of the outer periphery of the electrode catalyst layer 26a constituting the anode electrode 26, and the outer flow path groove 88a. And a plurality of inner flow channel grooves 88b facing portions other than the outer periphery. The cross-sectional area of the outer channel groove 88a is set larger than the cross-sectional area of the inner channel groove 88b by setting the channel width wider.

  As shown in FIG. 11, an oxidant gas flow path 90 extending in the direction of arrow B is provided on a surface 86 a of the cathode separator 86 facing the electrolyte membrane / electrode structure 82. The oxidant gas flow path 90 is positioned between the two outer flow path grooves 90a facing the outer periphery of the electrode catalyst layer 28a constituting the cathode electrode 28 and the outer flow path groove 90a. And a plurality of inner flow channel grooves 90b facing portions other than the outer periphery. The cross-sectional area of the outer channel groove 90a is set larger than the cross-sectional area of the inner channel groove 90b by setting the channel width wider.

  As shown in FIG. 10, a cooling medium flow path 92 is formed on the other surface 86 b of the cathode side separator 86 so as to face the other surface 84 b of the anode side separator 84. The cooling medium flow path 92 allows the cooling medium to flow in the direction of arrow B.

  In the fifth embodiment configured as described above, it is possible to effectively suppress deterioration of the solid polymer electrolyte membrane 24 and the like with a simple and economical configuration. The same effect as the embodiment can be obtained.

  As shown in FIGS. 12 and 13, the fuel cell 100 according to the sixth embodiment of the present invention includes an electrolyte membrane / electrode structure 102, an anode side separator 104, and a cathode side separator 106. The electrolyte membrane / electrode structure 102 may use, for example, any of the above-described electrolyte membrane / electrode structures 12, 52, or 62, and is configured in the same manner as the electrolyte membrane / electrode structure 12, for example.

  The anode-side separator 104 and the cathode-side separator 106 are made of, for example, a metal separator such as a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate having a metal surface subjected to anticorrosion surface treatment.

  On the surface 104a of the anode-side separator 104 facing the electrolyte membrane / electrode structure 102, a fuel gas flow path 108 having a corrugated cross section is formed by pressing into a wave shape. The fuel gas channel 108 is positioned between the outer channel groove 108a and the two outer channel grooves 108a opposed to the upper and lower sides of the outer periphery of the electrode catalyst layer 26a constituting the anode electrode 26. And a plurality of inner flow channel grooves 108b facing portions other than the outer periphery. The cross-sectional area of the outer channel groove 108a is set larger than the cross-sectional area of the inner channel groove 108b by setting the channel width wider.

  In the vicinity of the inlet and the outlet of the fuel gas channel 108, an inlet buffer part 110a and an outlet buffer part 110b each having a plurality of embosses are provided.

  As shown in FIG. 14, an oxidant gas flow path 112 extending in the direction of arrow B is provided on the surface 106 a of the cathode separator 106 facing the electrolyte membrane / electrode structure 102. The oxidant gas channel 112 is located between the two outer channel grooves 112a facing the outer periphery of the electrode catalyst layer 28a constituting the cathode electrode 28, and the outer channel groove 112a. And a plurality of inner flow channel grooves 112b facing portions other than the outer periphery. The cross-sectional area of the outer channel groove 112a is set larger than the cross-sectional area of the inner channel groove 112b by setting the channel width wider.

  In the vicinity of the inlet and the outlet of the oxidant gas channel 112, an inlet buffer unit 114a and an outlet buffer unit 114b each having a plurality of embosses are provided.

  A cooling medium flow path 116 is formed on the other surface 106b of the cathode separator 106 so as to face the other surface 104b of the anode separator 104 (see FIG. 12). The cooling medium channel 116 circulates the cooling medium in the direction of arrow B.

  In the sixth embodiment configured as described above, it is possible to effectively suppress deterioration of the solid polymer electrolyte membrane 24 and the like with a simple and economical configuration. The same effect as the embodiment can be obtained. In addition, you may enlarge the cross-sectional area of an outer side channel groove | channel by making a channel depth deep.

10, 50, 60, 70, 80, 100 ... Fuel cells 12, 52, 62, 82, 102 ... Electrolyte membrane / electrode structures 14, 16, 72, 74, 84, 86, 104, 106 ... Separator 18a ... Oxidation Agent gas inlet communication hole 18b ... Oxidant gas outlet communication hole 20a ... Cooling medium inlet communication hole 20b ... Cooling medium outlet communication hole 22a ... Fuel gas inlet communication hole 22b ... Fuel gas outlet communication hole 24 ... Solid polymer electrolyte membrane 26, 54, 64 ... anode electrodes 28, 56, 66 ... cathode electrodes 26a, 26aL, 26aS, 28a, 28aL, 28aS ... electrode catalyst layers 26b, 28b ... gas diffusion layers 30a, 30b ... protective sheet members 34, 88, 108 ... fuel Gas flow paths 34a, 36a, 34aL, 36aL, 90a, 108a, 112a ... outer flow path grooves 34b, 36b, 90b, 108 , 112b ... inner flow grooves 36,112 ... oxidant gas flow path 38 ... coolant flow

Claims (3)

The separator is laminated with an electrolyte membrane / electrode structure provided with electrodes each having an electrode catalyst layer and a gas diffusion layer on both sides of the solid polymer electrolyte membrane, and the separator is opposed to the electrode. A fuel cell in which a reaction gas flow path for flowing a reaction gas along the electrode surface direction is formed,
The reaction gas channel includes a plurality of channel grooves,
The cross-sectional area of the outer flow channel facing the outer periphery of the electrode is set larger than the cross-sectional area of the inner flow channel facing the other part of the electrode,
The fuel cell according to claim 1, wherein an outer peripheral end portion of the electrode catalyst layer is disposed opposite to the outer flow path groove. The fuel cell according to claim 1, wherein the electrode has an anode electrode and a cathode electrode,
The outer peripheral end of the anode electrode catalyst layer constituting the anode electrode and the outer peripheral end of the cathode electrode catalyst layer constituting the cathode electrode are in relation to the stacking direction of the electrolyte membrane / electrode structure and the separator. While being offset from each other,
The reaction gas channel has a fuel gas channel and an oxidant gas channel,
The outer peripheral end portion of the anode electrode catalyst layer is opposed to the outer flow channel groove of the fuel gas flow channel, and the outer peripheral end portion of the cathode electrode catalyst layer is an outer flow channel of the oxidant gas flow channel. A fuel cell facing the inside of the groove.   3. The fuel cell according to claim 1, wherein the outer flow path groove is constituted by a convex portion of the separator and a seal member. 4.

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