JP2017130364A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery that ensures durability of a membrane electrode assembly while suppressing increase in thickness.SOLUTION: A fuel battery comprises a cell 1 including gas diffusion layers 22a and 22c on both surfaces of a membrane electrode assembly 10, separators 30a and 30c that sandwich the membrane electrode assembly 10 and the gas diffusion layers 22a and 22c therebetween, first gas guiding flow paths a12 and a21 configured by grooves provided in a frame portion 36a of the separator 30a and second gas guiding flow paths c12 and c21 configured by grooves provided in a frame portion 36c of the separator 30c, and porous reinforcing members 50 which are thinner than the gas diffusion layer 22c and provided on at least one surface (on the side of the second gas guide flow paths c12 and c21 in the drawings) of the outer peripheral portion of the membrane electrode assembly 10 sandwiched between the frame portions 36a and 36c of the separators 30a and 30c.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell.

  A separator of a fuel cell is known that has a metal central portion that defines a gas flow path on the membrane electrode assembly side and a refrigerant flow path on the back side thereof, and a resin frame that surrounds the central portion. (See, for example, Patent Document 1). The frame portion is provided with a gas manifold and a refrigerant manifold. The frame part defines a gas guide channel for guiding gas from one of the gas manifold and the gas channel to the other on the membrane electrode assembly side, and one side of the refrigerant manifold and the refrigerant channel on the other side of the gas guide channel. A refrigerant guide channel for guiding the refrigerant is defined.

  Here, the gas flow path and the refrigerant flow path in the central portion of the separator extend in the same direction, and are formed integrally with the front and back surfaces by press molding a metal plate. For this reason, the thickness is suppressed at the central portion of the separator.

  However, since the gas manifold and the refrigerant manifold are at different positions in the planar direction of the membrane electrode assembly, the gas guide channel and the refrigerant guide channel extend in different directions. For this reason, it is necessary to form the gas guide channel and the refrigerant guide channel at intervals in the thickness direction of the frame, and the portion of the frame where the gas guide channel and the refrigerant guide channel are provided is a metal The thickness is greater than the central part. A single cell of the fuel cell includes a pair of such separators, and the pair of separators sandwich the gas diffusion layer and the membrane electrode assembly so that the gas guide flow path of the frame portion faces the membrane electrode assembly side.

Japanese Patent Laid-Open No. 2006-032008

  Here, in the case of a configuration in which the gas diffusion layer is provided in a portion sandwiched between the gas guide flow paths of the frame portions of the pair of separators, the thickness of the fuel cell increases. On the other hand, the thickness of the fuel cell can be suppressed by adopting a configuration in which the gas diffusion layer is not provided in the portion sandwiched between the gas guide channels of the frame portion. However, when a part of the membrane electrode assembly is sandwiched by the gas guide channel, the membrane electrode assembly is a portion sandwiched by the convex portions of the gas guide channel and at least one of the gas guide channels is a recess. The parts where the surface pressure does not act are alternately arranged. For this reason, when the membrane / electrode assembly repeatedly swells and contracts in such a state, stress is repeatedly applied to the same portion of the membrane / electrode assembly, and the durability of the portion may decrease.

  Then, an object of this invention is to provide the fuel cell which ensured the durability of the membrane electrode assembly, suppressing the increase in thickness.

  In the fuel cell in which a plurality of single cells are stacked, the single cell has a membrane electrode assembly in which a catalyst layer is provided on both surfaces of an electrolyte membrane and has a central portion and an outer peripheral portion surrounding the central portion First and second gas diffusion layers positioned so as to sandwich the center portion of the membrane electrode assembly, and metal first and second layers positioned so as to sandwich the center portion of the membrane electrode assembly Each of the first and second frame portions made of resin encloses the second central portion and the first and second central portions, respectively, and sandwiches the membrane electrode assembly together with the first and second gas diffusion layers. A first gas separator, a second separator, and the first and second frame portions through which the first gas, the second gas, and the refrigerant circulate at positions outside the outer peripheral portion of the membrane electrode assembly, respectively. A first gas circulation hole, a second gas circulation hole, and a refrigerant circulation hole; The two central portions define first and second gas flow paths on the membrane electrode assembly side, and first and second refrigerant flow paths on the back sides of the first and second gas flow paths, respectively. The first frame portion defines an uneven first gas guide channel that guides the first gas from one of the first gas flow hole and the first gas channel to the other on the membrane electrode assembly side. A first refrigerant guide channel that guides the refrigerant from one of the refrigerant circulation hole and the first refrigerant channel to the other of the first gas guide channel and the second frame portion An uneven second gas guide that sandwiches a part of the outer peripheral portion of the membrane electrode assembly together with one frame portion and guides the second gas from one of the second gas flow hole and the second gas flow path to the other. Defining a flow path, and from one side of the refrigerant flow hole and the second refrigerant flow path to the other side of the second gas guide flow path A second refrigerant guide channel for guiding the refrigerant is defined, and the outer peripheral portion of the membrane electrode assembly is disposed on at least one surface of the portion sandwiched between the first and second gas guide channels. This can be achieved by a fuel cell in which a porous reinforcing member thinner than each of the first and second gas diffusion layers is provided.

  A fuel cell in which the durability of the membrane electrode assembly is ensured while suppressing an increase in thickness can be provided.

FIG. 1A and FIG. 1B are views of a single cell, which is a fuel cell, viewed from the anode side and the cathode side, respectively. 2A is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 1A. 3A is a cross-sectional view taken along the line CC of FIG. 1A, and FIG. 3B is a cross-sectional view of a comparative example. FIG. 4 is a cross-sectional view of a single cell according to a first modification. FIG. 5A is a cross-sectional view of a single cell according to a second modification, FIG. 5B is a front view of the metal porous body 60, and FIG. 5C is an enlarged perspective view of an expanded portion. FIG. 6 is a cross-sectional view of a single cell according to a third modification.

  1A and 1B are views of a single cell 1 that is a fuel cell as viewed from the anode side and the cathode side, respectively. The fuel cell is configured by stacking a plurality of single cells 1. This fuel cell is a solid polymer fuel cell that generates power by receiving supply of an oxidant gas (for example, oxygen) called a cathode gas and a fuel gas (for example, hydrogen) called an anode gas as a reaction gas. . The anode gas and the cathode gas are examples of first and second gases.

  2A is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 1A. The single cell 1 includes a membrane electrode assembly (hereinafter referred to as MEA) 10, an anode side gas diffusion layer 22a and a cathode side gas diffusion layer 22c (hereinafter referred to as a diffusion layer), an anode side separator 30a and a cathode side separator 30c ( Hereinafter referred to as a separator), and a reinforcing member 50.

  The MEA 10 includes a substantially rectangular electrolyte membrane 11, one surface (upper surface in FIGS. 2A and 2B) and the other surface (lower surface in FIGS. 2A and 2B) of the electrolyte membrane 11. ) Include an anode-side catalyst layer 12a and a cathode-side catalyst layer 12c (hereinafter referred to as catalyst layers), respectively. That is, the catalyst layers 12 a and 12 c are not formed on the outer periphery of the electrolyte membrane 11. The catalyst layers 12a and 12c are formed, for example, by applying a carbon carrier carrying platinum (Pt) or the like and an ionomer having proton conductivity to the electrolyte membrane 11. A reinforcing member 50 is provided on a part of the cathode side surface of the outer periphery of the electrolyte membrane 11. Details of the reinforcing member 50 will be described later.

  The diffusion layers 22a and 22c are joined to the catalyst layers 12a and 12c, respectively. A water repellent layer (not shown) is formed on the MEA 10 side of the diffusion layers 22a and 22c. The diffusion layers 22a and 22c and the water repellent layer are formed of members having gas permeability and electronic conductivity, and are formed of a porous carbon member such as carbon cloth or carbon paper. Since the water repellent layer has smaller pores in the porous carbon member than the diffusion layers 22a and 22c, the water repellent layer retains moisture in the MEA 10 and suppresses a decrease in power generation performance due to drying of the electrolyte membrane 11.

  The separators 30a and 30c sandwich the MEA 10 together with the diffusion layers 22a and 22c. The separators 30a and 30c include metal center portions 33a and 33c and resin frame portions 36a and 36c surrounding the center portions 33a and 33c, respectively. Each of the central portions 33a and 33c has a shape in which a plurality of concave and convex grooves arranged in the short direction of the single cell 1 extend in the longitudinal direction of the single cell 1 as shown in FIG. A plurality of grooves are formed by press working. The central portions 33a and 33c are in partial contact with and electrically connected to the diffusion layers 22a and 22c, respectively, and the anode gas between the central portion 33a and the diffusion layer 22a and between the central portion 33c and the diffusion layer 22c, respectively. And an anode gas channel 34a and a cathode gas channel 34c (hereinafter referred to as gas channels) through which the cathode gas flows are defined. The anode gas and the cathode gas are examples of first and second gases, respectively.

  Openings 37a and 37c are formed in the frame portions 36a and 36c so as to surround the diffusion layers 22a and 22c, respectively. The central portions 33a and 33c are provided so as to close the openings 37a and 37c, respectively. As will be described in detail later, the frame portions 36 a and 36 c sandwich the outer peripheral portion of the electrolyte membrane 11. The separator 30a is manufactured by, for example, pressing a metal plate to manufacture a central portion 33a in which a plurality of concave and convex grooves are formed, and then setting the central portion 33a in an injection mold and applying resin. This is done by molding the frame portion 36c around the central portion 33a by injection molding. The manufacturing method of the separator 30c is also the same.

  The first gas communication holes a1 and a2, the second gas communication holes c1 and c2, and the refrigerant communication holes w1 and w2 (hereinafter referred to as holes) are formed outside the openings 37a and 37c of the frame parts 36a and 36c. Has been. Holes c1, w2, and a2 are formed on one short side of the separators 30a and 30c, and holes c2, w1, and a1 are formed on the other short side. The holes c1 formed in the separators 30a and 30c respectively communicate with each other to define a cathode inlet manifold. Similarly, holes c2, a1, a2, w1, and w2 formed in separators 30a and 30c, respectively, define a cathode outlet manifold, an anode inlet manifold, an anode outlet manifold, a refrigerant inlet manifold, and a refrigerant outlet manifold.

  Further, anode gas guide channels a12 and a21 (hereinafter referred to as guide channels) are defined on the electrolyte membrane 11 side of the frame portion 36a. The guide channels a12 and a21 are located on the opposite side across the central portion 33a. The guide channel a12 is defined by a plurality of grooves formed in an uneven shape in the frame portion 36a and a part of the outer peripheral portion of the electrolyte membrane 11 facing the plurality of grooves. The plurality of grooves that define the guide channel a12 extend so that the interval gradually increases from the hole a1 toward the opening 37a. The guide channel a12 guides the anode gas from the hole a1 to the gas channel 34a.

  Similarly, the guide channel a21 is defined by a plurality of grooves formed in an uneven shape in the frame portion 36a and a part of the outer peripheral portion of the electrolyte membrane 11 facing the plurality of grooves. The plurality of grooves that define the guide channel a21 extend from the opening 37a toward the hole a2 so that the intervals are gradually narrowed. The guide channel a21 guides the anode gas from the gas channel 34a to the hole a2. Accordingly, the anode gas is distributed from the hole a1 to the gas flow path 34a by the guide flow path a12, and is merged from the gas flow path 34a by the hole a2 by the guide flow path a21.

  Further, cathode gas guide channels c12 and c21 (hereinafter referred to as guide channels) are defined on the electrolyte membrane 11 side of the frame portion 36c. The guide channels c12 and c21 are located on the opposite side across the central portion 33a. The guide flow path c12 is defined by a plurality of grooves formed in a concavo-convex shape in the frame portion 36c and a reinforcing member 50 opposed to the plurality of grooves. The plurality of grooves that define the guide channel c12 extend so that the interval gradually increases from the hole c1 toward the opening 37c. The guide channel c12 guides the cathode gas from the hole c1 to the gas channel 34c.

  Similarly, the guide flow path c21 is defined by a plurality of grooves formed in a concavo-convex shape in the frame portion 36c and a reinforcing member 50 facing the plurality of grooves. The plurality of grooves that define the guide flow path c21 extend from the opening 37c toward the hole c2 so that the intervals are gradually narrowed. The guide channel c21 guides the cathode gas from the gas channel 34c to the hole c2. Therefore, the cathode gas is distributed from the hole c1 to the gas flow path 34c by the guide flow path c12, and is merged from the gas flow path 34c by the hole c2 by the guide flow path c21.

  The guide channels a12 and c21 are opposed to each other through a part of the outer periphery of the electrolyte membrane 11 and the reinforcing member 50. Similarly, the guide channels a21 and c12 are also a part of the outer periphery of the electrolyte membrane 11 and the reinforcing member. 50 to face each other. The guide channels a12 and c21 are examples of the first and second gas guide channels, and similarly, the guide channels a21 and c12 are examples of the first and second gas guide channels. Details will be described later.

  Here, as shown in FIGS. 1A and 1B, the holes a1 and c1 are located on the opposite sides via the MEA 10, and the holes a2 and c2 are located on the opposite sides via the MEA 10. Therefore, the anode gas and the cathode gas flow in opposite directions with respect to the MEA 10.

  Refrigerant guide channels w12 and w21 (hereinafter referred to as guide channels) are defined on the opposite sides of the frame 36a to the guide channels a12 and a21, respectively. Similarly, refrigerant guide channels w21 and w12 (hereinafter referred to as guide channels) are defined on the opposite side of the frame 36c from the guide channels c12 and c21, respectively.

  Here, although only the single cell 1 is shown in FIGS. 2A and 2B, the fuel cell is actually configured by stacking a plurality of single cells 1. Accordingly, the cathode separator of another single cell (not shown) is disposed above the separator 30a shown in FIGS. 2A and 2B. A flow path through which the refrigerant flows is defined between them, and the refrigerant flows from the hole w1 to the refrigerant flow path 35a through the guide flow path w12 and is discharged to the hole w2 through the guide flow path w21. Similarly, an anode side separator of another single cell (not shown) is arranged below the separator 30c shown in FIGS. 2A and 2B. Therefore, the refrigerant is distributed from the hole w1 to the refrigerant flow paths 35a and 36a by the guide flow path w12 of the frame portions 36a and 36c, and merges at the hole w2 by the guide flow path w21 of the frame portions 36a and 36c.

  Note that the plurality of concave and convex grooves that define the guide flow path w12 of the frame portions 36a and 36c extend from the hole w1 toward the openings 37a and 37c so that the intervals gradually increase. The plurality of concave and convex grooves that define the guide flow path w21 of the frame portions 36a and 36c extend from the openings 37a and 37c toward the hole 2 so that the intervals are gradually narrowed.

  As shown in FIGS. 1A and 2A, the frame portion 36a has a portion where guide channels a21 and w21 are defined on both sides and a portion where guide channels a12 and w12 are defined. Further, as shown in FIG. 1A, the directions in which the guide channels a21 and w21 extend are different from each other, and the same applies to the guide channels a12 and w12. Therefore, the grooves that respectively define the guide channels a21 and w21 are provided at intervals in the thickness direction of the frame portion 36a as shown in FIG. 2A, and in the portion where the guide channels a21 and w21 are defined. It is formed thicker than the central portion 33a. The same applies to the guide channels a12 and w12. Similarly, the portion where the guide channels c12 and w21 of the frame portion 36c are defined and the portion where the guide channels c21 and w12 are defined are also formed thicker than the central portion 33c.

  3A is a cross-sectional view taken along the line CC of FIG. 1A. As shown in FIG. 2A and FIG. 3A, porous reinforcement is provided in the outer peripheral portion of the electrolyte membrane 11 at the portion sandwiched between the guide channels a21 and c12 and the portion sandwiched between the guide channels a12 and c21. A member 50 is provided. The reinforcing member 50 is provided on a part of the surface on the cathode side of the outer peripheral portion excluding the central portion of the electrolyte membrane 11 and has a thin sheet shape. The reinforcing member 50 is provided in a portion sandwiched between the guide channels a21 and c12 and a portion sandwiched between the guide channels a12 and c21, but is not limited to this, for example, around the diffusion layer 22c. It may be framed so as to surround it. The reinforcing member 50 is, for example, a foam sintered body formed of a material including titanium, stainless steel, and carbon. However, the reinforcing member 50 is not limited thereto, and a metal fiber processed into a mesh shape, or a metal plate is cut and bent. It may be what you did.

  FIG. 3B is a cross-sectional view of a comparative example. In the comparative example, the reinforcing member 50 is not provided, and the electrolyte membrane 11 has a portion directly sandwiched between the convex portions of the guide flow paths a21 and c12, and at least one of the guide flow channels a21 and c12 is a concave surface. The parts where pressure does not act are arranged alternately. In this state, the electrolyte membrane 11 repeatedly swells and contracts, so that the portion sandwiched between the convex portions is difficult to swell and contract while the portion where the surface pressure does not act is repeatedly swelled and contracted. There is a risk that the durability of the electrolyte membrane 11 may be reduced due to repeated stress acting on a predetermined location. The same applies to the part of the electrolyte membrane 11 sandwiched between the guide channels a12 and c21.

  In the present embodiment, as shown in FIGS. 2A and 3A, the electrolyte membrane 11 is reinforced by the reinforcing member 50. Therefore, local stress concentration due to repeated swelling and shrinkage of the electrolyte membrane 11 as shown in FIG. 3B is alleviated, and the durability of the electrolyte membrane 11, that is, the durability of the MEA 10 is ensured. Further, none of the diffusion layers 22a and 22c exists between the guide channels a21 and c12 and between the guide channels a12 and c21. Thereby, increase of the thickness of the single cell 1 is suppressed.

  Further, since the reinforcing member 50 is porous, water passes through the reinforcing member 50 and the electrolyte membrane 11 between the anode gas and the cathode gas flowing through the guide flow paths a21 and c12, respectively. Here, as described above, the anode gas and the cathode gas flow in opposite directions through the MEA 10, the guide channel a21 is located on the downstream side of the anode gas from the guide channel a12, and the guide channel c12 is It is located upstream of the cathode gas from the guide channel c21. Here, since the moisture generated by the power generation of the MEA 10 flows downstream of the anode gas and the cathode gas, the amount of moisture present on the anode side and the cathode side is large on the downstream side of the anode gas and the cathode gas, but on the upstream side. Less. For this reason, there exists a possibility that it may be in the dry state rather than the optimal wet state of the electrolyte membrane 11 in each upstream of anode gas and cathode gas.

  However, in this embodiment, the guide channel a21 located on the downstream side of the anode gas and the guide channel c12 located on the upstream side of the cathode gas face each other with the electrolyte membrane 11 and the porous reinforcing member 50 interposed therebetween. ing. Accordingly, it is possible to ensure moisture permeation from the guide channel a21 to the guide channel c12 through the electrolyte membrane 11 and the reinforcing member 50, and maintain the upstream side of the electrolyte membrane 11 on the cathode side in an optimal wet state. can do. Similarly, it is possible to ensure moisture permeation from the guide channel c21 to the guide channel a12 via the electrolyte membrane 11 and the reinforcing member 50, and to maintain the upstream side of the electrolyte membrane 11 on the anode side in an optimal wet state. can do. Thereby, the fall of the power generation efficiency of MEA10 is suppressed.

  Further, as described above, in the present embodiment, the catalyst layers 12a and 12c are not formed on the outer peripheral portion of the electrolyte membrane 11 and the portion sandwiched between the frame portions 36a and 36c. For this reason, since it is suppressed that the usage-amount of platinum increases with the area increase of the catalyst layers 12a and 12c, the increase in the manufacturing cost of the single cell 1 is suppressed.

  Next, a modified example will be described. FIG. 4 is a cross-sectional view of the unit cell 1a of the first modification. FIG. 4 corresponds to FIG. 2A. In addition, about the structure same as the Example mentioned above, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  The reinforcing member 50a is adhered to almost the entire surface of the electrolyte membrane 11 on the cathode side, and has a sheet shape thinner than any of the diffusion layers 22a and 22c. The base material of the reinforcing member 50a includes a fluorine resin such as Teflon (registered trademark) and a pore layer of carbon particles, and further includes a fluorine ion exchange resin and carbon fibers having an average fiber diameter of 1 to 30 μm. ing. Here, since the reinforcing member 50a also functions as the water repellent layer in the first embodiment, it is not necessary to provide the water repellent layer in the cathode diffusion layer 22c. In this example, since the reinforcing member 50a having a water repellent layer function is not provided on the anode side, the anode diffusion layer 22a is provided with a water repellent layer (not shown). Since the fluorine ion exchange resin has good adhesion with the ion exchange resin that is the material of the electrolyte membrane 11 and adhesion with the catalyst layer 12c, adhesion between the reinforcing member 50a and the MEA 10 is ensured. . Moreover, since the carbon fiber is contained in the fluorine ion exchange resin, the rigidity of the reinforcing member 50a is ensured. Since the fluorine-based ion exchange resin is porous, moisture permeability is also ensured.

  Thus, the reinforcing member 50a is provided on almost the entire cathode side of the electrolyte membrane 11 and is thinner than any of the diffusion layers 22a and 22c, so that the increase in the thickness of the single cell 1a is suppressed while ensuring the durability of the MEA 10. Yes. Further, since the reinforcing member 50a is also permeable to moisture, the upstream side on the cathode side and the upstream side on the anode side of the electrolyte membrane 11 can be maintained in an optimal wet state. Further, since the reinforcing member 50a includes carbon fiber and is provided between the diffusion layer 22c and the MEA 10, it is possible to suppress the carbon fiber of the diffusion layer 22c from penetrating the electrolyte membrane 11.

  Examples of the carbon fiber include PAN-based carbon fiber and pitch-based carbon fiber. Examples of the form of carbon fiber include chopped fiber and milled fiber. Further, the MEA 10 and the reinforcing member 50a are bonded by, for example, a hot press method.

  Also in the first modified example, since the catalyst layers 12a and 12c are not formed on the outer peripheral portion of the electrolyte membrane 11, an increase in the manufacturing cost of the single cell 1a is suppressed. Further, the outer peripheral portion of the electrolyte membrane 11 is directly bonded to the reinforcing member 50a without the catalyst layer 12c interposed therebetween, and the adhesion between the electrolyte membrane 11 and the reinforcing member 50a is ensured.

  The reinforcing member 50a is not provided in the central portion of the electrolyte membrane 11, but is provided only in a portion sandwiched by the guide flow paths a21 and c12 and a portion sandwiched by the guide flow paths a12 and c21. May be. This is also because the electrolyte membrane 11 can be reinforced.

  FIG. 5A is a cross-sectional view of a unit cell 1b of a second modification. FIG. 5A corresponds to FIGS. 2A and 4. Unlike the first modification, in the second modification, a water repellent sheet 50b and a metal porous body 60 are provided instead of the reinforcing member 50a and the diffusion layer 22c. The water repellent sheet 50b has the same shape and size as the reinforcing member 50a, but does not include carbon fibers. That is, the water repellent sheet 50b does not have rigidity as compared with the reinforcing member 50a. The water repellent sheet 50b functions as a water repellent layer in the above-described embodiments. The electrolyte membrane 11 is bonded to the metal porous body 60 via the water repellent sheet 50b.

  The metal porous body 60 is made of a metal porous material such as stainless steel or titanium having conductivity, and is located between the expanded portion 62 and the guide channels a21 and c12 positioned in the opening portion 37c of the frame portion 36c. Punching part 61 and punching part 63 located between guide flow paths a12 and c21. FIG. 5B is a front view of the metal porous body 60. The expanded part 62 is located between the punching parts 61 and 63, is formed thicker than the punching parts 61 and 63 by cutting and bending, and has substantially the same thickness as the diffusion layer 22a. The thickness of the punching parts 61 and 63 is substantially the same, thinner than each of the expanded part 62 and the diffusion layer 22a, and a plurality of holes are formed by punching.

  As described above, the water-repellent sheet 50b is not as rigid as the reinforcing member 50a. However, the punching portion 61 is bonded to the water-repellent sheet 50b between the guide channels a21 and c12, and the guide channels a12 and The punching portion 63 is bonded to the water repellent sheet 50b between c21. Therefore, the durability of the MEA 10 is ensured by the punching portions 61 and 63. Thus, the punching parts 61 and 63 function as a reinforcing member. Moreover, since each thickness of the punching parts 61 and 63 is thinner than any of the expanded part 62 and the diffusion layer 22a, the increase in the thickness of the single cell 1b is suppressed. Moreover, since the punching parts 61 and 63 are porous, the upstream side on the cathode side and the upstream side on the anode side of the electrolyte membrane 11 can be maintained in an optimal wet state.

  FIG. 5C is an enlarged perspective view of the expanded portion 62. The expander 62 has a turtle shell-shaped mesh arranged alternately, and has a plurality of holes through which the cathode gas flowing on the MEA 10 side and the cathode gas flowing on the separator 30c side communicate with each other. The mesh is formed by a cutting and bending process in which a metal plate is fed to make a notch step by step with a mold. Cathode gas is diffused and supplied to the cathode catalyst layer through the gap formed by cutting and bending. Therefore, the expanded part 62 functions as a gas diffusion layer. Here, since the expanded part 62 and the punching parts 61 and 63 are integrally formed, the metal porous body 60 functions as a gas diffusion layer and a reinforcing member, and the number of parts is reduced.

  The metal porous body 60 and the water repellent sheet 50b are bonded together by a fluorine ion exchange resin that is a base material of the water repellent sheet 50b. For example, the bonding surface of the metal porous body 60 is roughened by blasting and bonded to the water repellent sheet 50b by hot pressing. Further, since the water-repellent sheet 50b contains an electrolyte ionomer, the adhesion surface of the metal porous body 60 is subjected to a hydrophilic treatment such as plasma treatment, and is adhered to the water-repellent sheet 50b by hot pressing. Alternatively, the bonding surface of the metal porous body 60 may be subjected to a hydrophilic treatment, an ionomer solution is applied to the bonding surface of the metal porous body 60, and the water-repellent sheet 50b is attached and dried.

  Also in the second modification, since the catalyst layers 12a and 12c are not formed on the outer peripheral portion of the electrolyte membrane 11, an increase in the manufacturing cost of the single cell 1b is suppressed. Further, the outer peripheral portion of the electrolyte membrane 11 is directly bonded to the water-repellent sheet 50b without passing through the catalyst layer 12c, and the adhesion between the electrolyte membrane 11 and the water-repellent sheet 50b is ensured.

  FIG. 6 is a cross-sectional view of a unit cell 1c according to a third modification. 6 corresponds to FIGS. 2A, 4 and 5A. Unlike the central portion 33c described above, the central portion 33cc of the third modification has a flat plate shape with no irregularities. Further, the expanded portion 62c of the metal porous body 60c is in contact with the central portion 33cc, and is formed to be thicker than the expanded portion 62 of the metal porous body 60 of the second modification because the central portion 33cc is flat. Yes.

  In addition, the frame portion 36cc of the separator 30cc is not formed with a plurality of concave and convex grooves that define the guide channels w12 and w21, and the guide channels w12 and w21 of the above-described embodiments and modifications are formed. The part where it is is flat. For this reason, the separator 30cc is formed thinner than the separator 30c of the second modification. However, the guide passages w12 and w21 are formed in the separator 30a. Although not shown in FIG. 6, the anode-side separator of another single cell (not shown) stacked on the lower side of the single cell 1c in FIG. The refrigerant flow path of the single cell 1c and the separator 30cc of the single cell 1c define a guide flow path through which the refrigerant flows, and a refrigerant flow path 35c is defined on the opposite side of the central portion 33cc of the single cell 1c from the MEA 10. Further, a gas flow path 34c is defined in the expanded portion 62c on the MEA 10 side of the central portion 33cc.

  Even in such a configuration, the durability of the MEA 10 is ensured while suppressing the thickness of the single cell 1c, and the upstream side on the cathode side and the upstream side on the anode side of the electrolyte membrane 11 can be maintained in an optimal wet state. .

  Further, the third modification differs from the second modification in that the separator 30cc on the cathode side is not an uneven shape but is a flat plate, and the frame 36cc is not provided with a groove corresponding to the second refrigerant flow path. . Here, the expanded part 62c also has the function of the second gas diffusion layer. Also in the third modified example, since the catalyst layers 12a and 12c are not formed on the outer peripheral portion of the electrolyte membrane 11, an increase in the manufacturing cost of the single cell 1c is suppressed. Further, the outer peripheral portion of the electrolyte membrane 11 is directly bonded to the water-repellent sheet 50b without passing through the catalyst layer 12c, and the adhesion between the electrolyte membrane 11 and the water-repellent sheet 50b is ensured.

  Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

  In the above-described embodiments and modifications, the catalyst layers 12a and 12c may be formed up to the outer peripheral portion of the electrolyte membrane 11 and the portions sandwiched between the frame portions 36a and 36c. In this case, the portion that sandwiches the catalyst layers 12a and 12c of the frame portions 36a and 36c is made of carbon black, graphite, or a resin in which metal powder or fiber is dispersed, thereby ensuring conductivity, and the electrolyte. It is also possible to secure an area where the film 11 can generate power.

  In the above-described embodiments and modifications, the reinforcing members 50 and 50a, the punching portions 61 and 63, and the metal porous bodies 60 and 60c are provided on the cathode side, but may be provided on the anode side. When the porous metal body 60c is provided on the anode side, it is necessary to arrange a separator having a flat central portion on the anode side instead of the cathode side, and to arrange a separator having an uneven central portion on the cathode side. is there. Further, the reinforcing members 50 and 50a may be provided on both the cathode side and the anode side.

  In the above-described embodiments and modifications, none of the diffusion layers 22a and 22c is sandwiched between the frame portions 36a and 36c, but only one of the diffusion layers 22a and 22c may be sandwiched between the frame portions 36a and 36c. Moreover, in the said Example and modification, although anode gas and cathode gas flow in the mutually opposite direction on both sides of MEA10, the structure which flows in the same direction may be sufficient.

  In the second and third modifications, a reinforcing member 50a may be used instead of the water repellent sheet 50b.

1, 1a, 1b, 1c Single cell 10 Membrane electrode assembly (MEA)
11 Electrolyte membrane 12a Anode catalyst layer (catalyst layer)
12c Cathode side catalyst layer (catalyst layer)
22a Anode side gas diffusion layer (gas diffusion layer)
22c Cathode side gas diffusion layer (gas diffusion layer)
30a Anode-side separator (first separator)
30c Cathode side separator (second separator)
33a, 33c central part (first and second central part)
34a Anode gas channel 34c Cathode gas channel 35a, 35c Refrigerant channel 36a, 36c Frame (first and second frame)
50, 50a Reinforcing member 50b Water repellent sheet 60, 60c Metal porous body 61, 63 Punching part 62 Expanding part a1, a2 Anode gas communication hole c1, c2 Cathode gas communication hole w1, w2 Refrigerant communication hole a12, a21, c12, c21 Gas guide channel w12, w21 Refrigerant guide channel

Claims (1)

In a fuel cell in which a plurality of single cells are stacked,
The single cell is
A catalyst layer is provided on both surfaces of the electrolyte membrane, and a membrane electrode assembly having a central portion and an outer peripheral portion surrounding the central portion;
First and second gas diffusion layers positioned so as to sandwich the central portion of the membrane electrode assembly,
Metal first and second center portions positioned so as to sandwich the center portion of the membrane electrode assembly, resin first and second frame portions surrounding the first and second center portions, respectively. Each of the first and second separators sandwiching the membrane electrode assembly together with the first and second gas diffusion layers,
The first and second frame portions are a first gas flow hole and a second gas flow hole through which a first gas, a second gas, and a refrigerant flow, respectively, at positions outside the outer peripheral portion of the membrane electrode assembly. And a refrigerant circulation hole,
The first and second central portions define first and second gas flow paths on the membrane electrode assembly side, respectively, and first and second refrigerants on the back sides of the first and second gas flow paths, respectively. Define the flow path,
The first frame portion defines an uneven first gas guide channel that guides the first gas from one of the first gas flow hole and the first gas channel on the membrane electrode assembly side, Demarcating a first refrigerant guide channel for guiding the refrigerant from one of the refrigerant flow hole and the first refrigerant channel to the other on the back side of the first gas guide channel;
The second frame portion sandwiches a part of the outer peripheral portion of the membrane electrode assembly together with the first frame portion, and passes the second gas from one of the second gas flow hole and the second gas flow path to the other. A second refrigerant guide that defines a concave and convex second gas guide channel to guide and guides the refrigerant from one side of the refrigerant flow hole and the second refrigerant channel to the other side of the second gas guide channel. Define the flow path,
The outer peripheral portion of the membrane electrode assembly has a porous shape thinner than each of the first and second gas diffusion layers on at least one surface of a portion sandwiched between the first and second gas guide channels. A fuel cell provided with a reinforcing member.

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