JP2006309989A - Fuel cell stack, fuel cell therewith, and separator for fuel cell and fuel cell mounting vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell stack which can maintain the durability of a MEA and can prevent a laminated unit cell from laterally shifting without making the size large and increasing the number of components, and to provide this fuel cell stack. <P>SOLUTION: The fuel cell stack 23 is constructed by laminating a plurality of unit cells 15. The unit cell comprises the MEA 10 wherein an anode electrode 14 is arranged on one side of an electrolyte film 11, and a cathode electrode 17 is arranged on the other side; and separators 18 and 19 arranged on each side of the MEA 10. Engagements to engage with each other are provided on contact surfaces between the separators arranged adjacently by lamination of the unit cells 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell stack formed by laminating a plurality of single cells each including a membrane-electrode assembly and separators disposed on both sides of the membrane-electrode assembly, and a fuel including the fuel cell stack The present invention relates to a battery, a fuel cell separator, and a fuel cell vehicle.

  Conventionally, a general polymer electrolyte fuel cell includes an electrolyte membrane composed of an ion exchange membrane, an anode electrode (fuel electrode) composed of a catalyst layer and a diffusion layer disposed on one surface of the electrolyte membrane, and the electrolyte membrane. A cathode electrode (oxidant electrode) composed of a catalyst layer and a diffusion layer disposed on the other surface of the electrode, a membrane-electrode assembly (MEA: hereinafter referred to simply as “MEA”), and this MEA And a separator disposed on each side of the fuel cell stack. A plurality of single cells are stacked to form a fuel cell stack.

  As a fuel cell stack having such a configuration, for example, the surface has a fluid flow path formed of a zigzag shape or a plurality of parallel concave grooves, and a convex shape is formed on the back surface at a position opposite to the fluid flow path. There is a fuel cell stack in which a pair of metal separators are disposed on both sides of the MEA to form a single cell, and the metal separators are stacked adjacent to each other. (For example, refer to Patent Document 1).

Here, when a fuel cell including such a fuel cell stack is mounted on a vehicle such as an automobile, for example, the cell stack is placed in a lateral direction (cell A force that tends to shift in the direction intersecting the stacking direction may act. For this reason, in the fuel cell stack, various means for preventing the lateral displacement of the stacked single cells are employed. Examples of this means include fixing the outer peripheral portion of the cell and applying a strong compressive load to the cell stack.
JP 2004-127711 A JP 2000-90956 A JP 2003-10032 A2 JP 2002-157551 A JP 2002-313399 A

  However, in the conventional techniques described in Patent Documents 1 to 5 described above, the problem of preventing lateral shift from occurring in the stacked single cells is not discussed, and even the idea is not described.

  Further, in order to prevent lateral displacement in the stacked single cells, the conventional technique for fixing the outer periphery of the cells increases the size (size) of the fuel cell stack and increases the number of parts. On the other hand, in the related art that prevents a lateral displacement from occurring in the stacked single cells by applying a strong compressive load to the cell stack, the durability of the MEA may be reduced by the load. In addition, it is necessary to secure a frictional force for preventing lateral slippage.

  The present invention has been made in view of such circumstances, and it is possible to maintain the durability of the MEA, as well as to increase the physique and to increase the number of parts without causing lateral shift in the stacked single cells. It is an object of the present invention to provide a fuel cell stack that can be prevented from occurring, a fuel cell including the fuel cell stack, a fuel cell separator, and a fuel cell vehicle.

  To achieve this object, the present invention provides an MEA in which an anode electrode is disposed on one surface of an electrolyte membrane and a cathode electrode is disposed on the other surface, and separators disposed on both sides of the MEA. And a plurality of unit cells, each of which is provided with an engaging portion that engages with each other on contact surfaces of separators arranged adjacent to each other by stacking the unit cells. A fuel cell stack is provided.

  In the fuel cell stack having this configuration, each single cell can be stacked in a state where the engaging portions formed on the contact surfaces of the separators arranged adjacent to each other are engaged. It is possible to prevent a lateral shift from occurring in the formed single cell. More specifically, it is possible to suppress (prevent) the occurrence of a shift in the direction intersecting the stacking direction between adjacent separators. Therefore, unlike the prior art, in order to prevent lateral displacement of the stacked single cells, it is not necessary to apply a strong compressive load to the MEA, and the durability of the MEA is not adversely affected. Further, the size of the fuel cell stack does not increase and the number of parts does not increase.

  In the fuel cell stack according to the present invention, the contact surface between the separators includes a region corresponding to the power generation unit, and a region corresponding to the non-power generation unit having a manifold forming portion and an edge, and the engagement The part can be provided in at least one of a region corresponding to the power generation unit and a region corresponding to the edge.

  Further, in the fuel cell stack according to the present invention, the engaging portion formed on the contact surface of the one adjacent separator is constituted by an engaging convex portion having a convex shape, and the contact surface of the other separator is formed on the contact surface. The formed engaging portion can be constituted by an engaging concave portion having a concave shape with which the engaging convex portion is engaged.

  Furthermore, the separator has a concavo-convex shape, the inside of the convex portion of the concavo-convex shape serves as a fluid flow path, and the contact surface between the separators is constituted by the outer top surface of the convex portion. You can also.

  In the fuel cell stack according to the present invention, a concave space can be formed inside the convex portion of the separator by the engaging convex portion. Here, in the case where the inside of the convex portion is a fluid flow path, by forming a concave space in the fluid flow path (inside the convex portion), the cross-sectional area of the fluid flow path is increased. Can do. For this reason, in addition to the advantages described above, the pressure loss generated in the fluid flow path can be reduced. Moreover, since the contact surface between adjacent separators is a concave surface or a convex surface, since the said contact area becomes large compared with the case where the contact surface between the said separator is planar shape, the contact resistance between the said separators reduces. For this reason, the power generation efficiency is further improved. Furthermore, by allowing the generated water to pass through the concave space, it is possible to secure a flow path for the fluid to flow, and to further reduce the pressure loss generated in the fluid flow path.

  Further, in the case of the configuration in which the concave space is formed inside the convex portion of the separator (fluid flow path), it is more preferable to circulate oxidant gas through the fluid flow path in which the concave space is formed. It is.

  The present invention also provides a fuel cell comprising the fuel cell stack described above. This fuel cell can prevent the lateral displacement of the stacked single cells without applying a strong compressive load to the MEA, so that the durability of the MEA can be maintained. Also, the physique does not increase and the number of parts does not increase.

  In the present invention, when the separator is laminated on the MEA, the protrusion is defined as “convex” when viewed from the outer surface (the surface opposite to the surface in contact with the MEA), and is depressed. The case is described as “concave”.

  Further, the present invention is a fuel cell separator incorporated in a fuel cell, and when stacked, an engaging portion that engages with the adjacent separator is formed on a contact surface with the adjacent separator. A separator for a fuel cell is provided.

  In the separator for a fuel cell having this configuration, since the engagement portion that engages with the adjacent separator is formed on the contact surface with the adjacent separator, the engagement portions are engaged with each other. Can be stacked. Therefore, it is possible to suppress (prevent) the occurrence of lateral shift (shift in the direction intersecting the stacking direction between adjacent separators) when stacked.

  The contact surface of the separator can be a surface that is substantially perpendicular to the stacking direction.

  Further, the present invention is a vehicle equipped with a fuel cell according to the present invention described above, wherein the single cell stacking direction of the fuel cell stack is a direction intersecting with the front-rear direction of the vehicle. A fuel cell vehicle equipped with a fuel cell is provided.

  Here, usually, in a car or the like, for example, an inertial force acts in the vehicle front-rear direction when the vehicle starts or brakes, so the stacking direction of the single cells of the fuel cell mounted on the vehicle is relative to the vehicle front-rear direction. When the direction intersects, the inertial force causes a lateral shift (shift in the direction intersecting the stacking direction) in the single cell. However, in the fuel cell vehicle according to the present invention, even if the stacking direction of the single cells is a direction intersecting the front-rear direction of the vehicle, the single cells (separators) of the fuel cells are Therefore, it is possible to prevent the shift in the direction intersecting the stacking direction.

  The stacking direction of the single cells is not particularly limited, but can be mounted so as to be in a direction substantially orthogonal to the vehicle front-rear direction. The direction substantially orthogonal to the vehicle front-rear direction includes a direction substantially perpendicular to the ground and substantially orthogonal to the vehicle front-rear direction, and a direction substantially horizontal to the ground and substantially orthogonal to the vehicle front-rear direction. is there.

  A fuel cell stack according to the present invention, a fuel cell including the fuel cell stack, a fuel cell separator, and a fuel cell vehicle are provided with engagement portions formed on contact surfaces of separators arranged adjacent to each other. Since each single cell can be laminated in a state where the two are engaged, it is possible to prevent lateral displacement of the laminated single cells. For this reason, it is not necessary to apply a strong compression load to the MEA to prevent the occurrence of the lateral shift, and the durability of the MEA can be maintained. Further, the size of the fuel cell stack does not increase and the number of parts does not increase. As a result, the reliability is improved, and a high-performance and compact fuel cell stack, a fuel cell, a fuel cell separator, and a fuel cell vehicle can be provided.

  Next, a fuel cell stack and a fuel cell according to preferred embodiments of the present invention will be described with reference to the drawings. In addition, embodiment described below is the illustration for demonstrating this invention, and this invention is not limited only to these embodiment. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  FIG. 1 is an overall schematic view of a fuel cell including the fuel cell stack according to the present embodiment in a posture in which the cell stacking direction is the vertical direction, and FIG. 2 is a configuration of the fuel cell stack according to the present embodiment. FIG. 3 is a cross-sectional view showing an enlarged part of a single cell as an element, and FIG. 3 is a cross-sectional view showing a part of a state in which a plurality of single cells shown in FIG. 2 are stacked.

  The fuel cell described in the present embodiment is a solid polymer electrolyte fuel cell, and can be mounted on, for example, a fuel cell vehicle, but may be used other than the vehicle. .

  As shown in FIGS. 1 to 3, the fuel cell 1 according to the present embodiment includes an electrolyte membrane 11 made of an ion exchange membrane, an anode electrode 14 (fuel electrode) disposed on one surface of the electrolyte membrane 11, and A MEA 10 (membrane-electrode assembly) composed of a cathode electrode 17 (oxidant electrode) disposed on the other surface of the electrolyte membrane 11; a separator 18 disposed on the anode electrode 14 side across the MEA 10; A single cell 15 is provided, which is formed by overlapping a separator 19 disposed on the cathode electrode 17 side with the MEA 10 interposed therebetween. One or more single cells 15 are stacked to form a module 9 (in the example shown, one cell constitutes one module), and this module 9 is stacked to form a module group. A terminal 20, an insulator 21, and an end plate 22 are arranged at both ends in the stacking direction to form a fuel cell stack 23, and the fuel cell stack 23 is fastened in the cell stacking direction and is extended outside the fuel cell stack 23 in the cell stacking direction. It consists of a member 24 (for example, a tension plate, a through bolt, etc.) and a member fixed with a bolt 25 or a nut.

  The separator 18 disposed on the anode electrode 14 side with the MEA 10 in between is an uneven shape in which a plurality of convex portions 31A and concave portions 32A are alternately arranged in parallel as shown in FIG. The inside of the convex portion 31A is a fluid flow path 33A. A fuel gas (hydrogen in the present embodiment) flows through the fluid flow path 33A, and the fuel gas is supplied to the MEA 10.

  The separators 18 and 19 are, for example, conductors based on metal, and play a role of preventing mixing of different fluids supplied to cells adjacent to each other.

  A concave engagement concave portion 35 is formed on the outer top surface 34A of the convex portion 31A of the separator 18, and the engagement concave portion 35 exists in a convex shape in the fluid flow path 33A. The engagement recess 35 is formed along the flow direction of the fuel gas flowing through the fluid flow path 33A. An engagement convex portion 37 formed on the outer top surface 34B of the separator 19, which will be described in detail later, is fitted into the engagement concave portion 35. The contact surfaces of the outer top surface 34A and the outer top surface 34B are surfaces that are substantially perpendicular to the stacking direction of the single cells. That is, the contact surface between adjacent separators is a surface substantially perpendicular to the stacking direction of the single cells.

  The separator 19 disposed on the cathode electrode 17 side with the MEA 10 interposed therebetween is particularly an uneven shape in which a plurality of convex portions 31B and a plurality of concave portions 32B are alternately arranged in parallel as shown in FIG. The inside of the convex portion 31B is a fluid flow path 33B. An oxidant gas (air in the present embodiment) flows through the fluid flow path 33B, and the oxidant gas is supplied to the MEA 10.

  A convex engagement convex portion 37 is formed on the outer top surface 34B of the convex portion 31B of the separator 19, and a concave space 38 is formed in the fluid flow path 33B by the engagement convex portion 37. Yes. The engagement convex portion 37 is formed along the flow direction of the oxidant gas flowing through the fluid flow path 33B, and is fitted into the engagement concave portion 35 described above. As will be described in detail later, the recessed space 38 can be a flow path through which generated water flows.

  When stacking the single cells 15, first, the separator 19 of the next single cell 15 is overlaid on the separator 18 of the first single cell 15. At this time, the next step is to place the next in the engagement recess 35 of the first single cell 15. The engaging projection 37 of the single cell 15 is fitted. By doing so, the first single cell 15 and the next single cell 15 stacked on the single cell 15 are laterally displaced from each other by the engagement of the engagement concave portion 35 and the engagement convex portion 37, that is, Generation | occurrence | production to the direction which cross | intersects the lamination direction between adjacent separators can be suppressed (prevented). In this way, as shown in FIG. 3, a plurality of single cells 15 are stacked to form a fuel cell stack 23.

  Note that, by stacking a plurality of single cells 15, a space 40 (see FIG. 3) formed between the single cell 15 and the single cell 15 adjacent to the single cell 15 serves as a cooling water flow path.

In the fuel cell 1 according to the present embodiment, when fuel gas (hydrogen) is supplied to the fluid flow path 33A and oxidant gas (air) is supplied to the fluid flow path 33B,
On the anode electrode side, H ₂ → 2H ⁺ + 2e ⁻
On the cathode side, (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O
As a whole fuel cell, H ₂ + (1/2) O ₂ → H ₂ O
The battery reaction occurs.

  By this battery reaction, the generated water generated on the cathode electrode 17 side is discharged to the outside through the concave space 38 formed in the fluid flow path 33B. Therefore, the generated water does not interfere with the flow of the oxidant gas, the flow path of the oxidant gas can be ensured, the pressure loss generated in the fluid flow path 33B can be reduced, and the generated water can be reduced. Can be improved.

  Moreover, since the cross-sectional area (volume) of the fluid flow path 33B is increased due to the presence of the concave space 38, the pressure loss generated in the fluid flow path 33B can be further reduced. And since the contact surface between adjacent separators is a concave surface or a convex surface, since the said contact area becomes large compared with the case where the contact surface between the said separator is planar shape, the contact resistance between the said separators reduces. .

  The fuel cell 1 according to the present invention is mounted on a vehicle so as to cross the vehicle in the front-rear direction, and a fuel cell vehicle (not shown) is provided. In this fuel cell vehicle, the single cells 15 (separators) that are components of the mounted fuel cell 1 are engaged with each other by the engagement recess 35 and the engagement projection 37. For this reason, when the unit cell 15 is mounted on the vehicle so that the stacking direction of the single cells 15 intersects the vehicle front-rear direction, for example, inertial force acts in the vehicle front-rear direction when the vehicle starts or brakes. However, the inertial force does not shift the single cell 15 in the direction crossing the stacking direction. Therefore, the fuel cell 1 according to the present invention can be mounted on the vehicle so as to be in a direction crossing the front-rear direction of the vehicle.

  The stacking direction of the single cells 15 is not particularly limited, but can be mounted so as to be in a direction substantially orthogonal to the vehicle front-rear direction. The direction substantially orthogonal to the vehicle front-rear direction includes a direction substantially perpendicular to the ground and substantially orthogonal to the vehicle front-rear direction, and a direction substantially horizontal to the ground and substantially orthogonal to the vehicle front-rear direction. is there.

  The fuel cell 1 may be mounted on the vehicle such that the stacking direction of the single cells 15 is substantially parallel to the vehicle front-rear direction.

  In the present embodiment, the case where the separators 18 and 19 having the concavo-convex shape are applied has been described. However, the present invention is not limited to this, and the separator is a surface opposite to the MEA 10 when stacked on the MEA 10. However, a flat (flat) shape may be applied. In this case, the engagement concave portion 35 and the engagement convex portion 37 can be formed at any place on the contact surfaces of the separators. For example, it may be an arbitrary location corresponding to the power generation unit or an arbitrary location corresponding to the non-power generation unit. More preferably, the engagement concave portion 35 and the engagement convex portion 37 can be provided at any location corresponding to the power generation portion or at any location corresponding to the non-power generation portion excluding the manifold forming portion. Moreover, you may form in the outer surface corresponding to a fluid flow path.

  In the present embodiment, the shape of the fluid flow paths 33A and 33B has been described as having a substantially trapezoidal cross section in which the MEA 10 side is wide and the side away from the MEA 10 is narrow. The shapes of 33A and 33B can be determined as desired, such as a substantially rectangular cross section. Moreover, although the case where the fluid flow paths 33A and 33B are straight flow paths has been described in the present embodiment, the present invention is not limited to this, and a serpentine flow path may be formed.

  In the present embodiment, the case where the concave space 38 is formed in the fluid flow path 33B by forming the engaging convex portion 37 has been described. As shown in FIG. 4, it may be composed of a convex part molded integrally with the separator 19, and as shown in FIG. Also good.

  Furthermore, in the present embodiment, the case where the convex portion exists in the fluid flow path 33A by forming the engaging concave portion 35 has been described. However, the present invention is not limited to this, and for example, the convex portion 31A It is also possible to secure the thickness of the outer top surface 34A so that the engaging recess 35 does not protrude into the fluid flow path 33A.

  In the present embodiment, the case where the engaging recess 35 and the engaging protrusion 37 are formed as the engaging portion has been described. The shape is not particularly limited as long as the shapes can be engaged with each other. Moreover, the number of installation of the engagement recessed part 35 and the engagement convex part 37 can be determined arbitrarily.

In the fuel cell provided with the fuel cell stack concerning an embodiment of the invention, it is the whole schematic figure in the posture which made the cell lamination direction the up-and-down direction. It is sectional drawing which expands and shows a part of single cell which is a component of the fuel cell stack concerning embodiment of this invention. It is sectional drawing which shows a part of the state which laminated | stacked multiple single cells shown in FIG. It is sectional drawing which expands and shows a part of single cell concerning other embodiment of this invention. It is sectional drawing which expands and shows a part of single cell concerning other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 11 ... Electrolyte membrane, 14 ... Anode electrode, 15 ... Single cell, 17 ... Cathode electrode, 18, 19 ... Separator, 23 ... Fuel cell stack, 31A, 31B ... Convex part, 32A, 32B ... Concave shape Part, 33A, 33B ... Fluid flow path, 34A, 34B ... Outer top surface, 35 ... Engaging recess, 37 ... Engaging projection, 38 ... Concave space

Claims (9)

A membrane-electrode assembly in which an anode electrode is disposed on one surface of an electrolyte membrane and a cathode electrode is disposed on the other surface, and separators disposed on both sides of the membrane-electrode assembly. A fuel cell stack comprising a plurality of stacked single cells,
A fuel cell stack in which engagement portions that engage with each other are provided on contact surfaces of separators that are arranged adjacent to each other by stacking the single cells.   The contact surface between the separators includes a region corresponding to a power generation unit and a region corresponding to a non-power generation unit having a manifold forming portion and an edge, and the engagement unit includes a region corresponding to the power generation unit and The fuel cell stack according to claim 1, wherein the fuel cell stack is provided in at least one of the regions corresponding to the edge portions.   The engaging part formed on the contact surface of the one adjacent separator is an engaging convex part having a convex shape, and the engaging part formed on the contact surface of the other separator is the engaging convex part. The fuel cell stack according to claim 1, wherein the fuel cell stack includes an engaging recess provided with a recess to engage with.   4. The separator according to claim 1, wherein the separator has a concavo-convex shape, an inner side of the convex portion of the concavo-convex shape serves as a fluid flow path, and a contact surface between the separators is an outer top surface of the convex portion. The fuel cell stack according to any one of the above.   The fuel cell stack according to claim 4, wherein a concave space is formed inside the convex portion by the engaging convex portion.   The fuel cell stack according to claim 5, wherein an oxidant gas is circulated through a fluid flow path of a separator formed with the engaging projections.   A fuel cell comprising the fuel cell stack according to any one of claims 1 to 6. A separator for a fuel cell incorporated in a fuel cell,
A separator for a fuel cell, wherein an engagement portion that engages with an adjacent separator is formed on a contact surface with the adjacent separator when stacked. A fuel cell vehicle equipped with the fuel cell according to claim 7,
A fuel cell-equipped vehicle on which the fuel cell is mounted so that the unit cell stacking direction of the fuel cell stack intersects with the vehicle front-rear direction.

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