JP2008311107A - Fuel cell and separator thereof - Google Patents

Abstract

In a so-called flat metal fuel cell, a short circuit between separators can be effectively prevented.
A separator 20 for a flat metal fuel cell, a resin frame 23, a pair of metal flat plates 21 and 22 sandwiching the resin frame 23, and the metal flat plates 21 and 22 and the resin frame 23 are bonded. And an insulating layer is formed on the metal flat plates 21 and 22 by protruding a part of the heat-pressed adhesive member 24 to the back side of the metal flat plates 21 and 22. A protrusion hole 26 is provided. The protrusion hole 26 is preferably provided in the outer peripheral portion of the separator 20, and more preferably provided in the vicinity of a portion where adjacent separators 20 can come into contact with each other to cause a short circuit.
[Selection] Figure 9

Description

  The present invention relates to a fuel cell and a separator thereof. More specifically, the present invention relates to the structure of a so-called flat metal fuel cell.

  As separators for fuel cells, in addition to those formed with groove-like channels of reaction gas (hydrogen gas, oxidizing gas) and refrigerant (cooling water) on the surface, there are also so-called flat separators with a flat surface It is used. In recent years, a separator having a two-sheet structure in which a coolant channel layer is formed between two electrode-facing plates has also been proposed (see, for example, Patent Document 1).

Conventionally, such a separator of a flat metal type fuel cell having a two-sheet structure is formed by sealing and bonding a pair of metal flat plates (plates) and, for example, a laminate resin having an adhesive layer by heat bonding. In this case, a pair of metal flat plates are joined by resin, for example. Further, a protrusion is formed on one of the metal flat plates (plates) by pressing, or a coolant channel is formed by inserting a porous sheet between the metal flat plates.
JP 2006-164765 A

  However, since the resin is used for the flat metal type fuel cell separator as described above, the rigidity may be lowered during a high temperature operation exceeding 80 ° C., for example. Under such circumstances, when a bending stress is generated due to, for example, displacement of other members such as a gasket, the separators may come into contact with each other to cause a short circuit.

  In view of the above, an object of the present invention is to provide a fuel cell and a separator thereof that can effectively prevent a short circuit between separators in a so-called flat metal fuel cell.

  As described above, if the metal separator bends due to the influence received when operating at a high temperature, a short circuit may occur between the separators. In this case, as a general measure for avoiding a short circuit, an insulating layer may be sandwiched between the contact surfaces, but this may lead to an increase in cost and a decrease in productivity. Further, as an alternative measure, for example, a metal flat plate can be wrapped with an adhesive film, but the same is true in that there is a risk of increasing costs and reducing productivity. With regard to such a current situation, the present inventor, who has further studied focusing on the structure using a metal flat plate, has obtained new knowledge that leads to the solution of such problems.

  The present invention is based on such knowledge, and in a separator for a flat metal fuel cell, a resin frame, a pair of metal flat plates that sandwich the resin frame, and an adhesive member that bonds the metal flat plate and the resin frame. The metal flat plate is provided with a protrusion hole for forming an insulating layer by protruding a part of the heat-pressed adhesive member to the back side of the metal flat plate.

  When the resin frame is sandwiched between the metal flat plates with the adhesive member interposed therebetween and pressure is applied while heating, a part of the adhesive member protrudes from the protrusion hole and turns around to the back side. According to the separator of the present invention, it is possible to form an insulating layer on the back surface of the metal flat plate by melting the adhesive member into the back side of the flat metal plate and solidifying the adhesive member.

  In such a separator, the protrusion hole is preferably provided in the outer peripheral portion of the separator, and more preferably provided in the vicinity of a portion where adjacent separators can come into contact with each other to cause a short circuit. It is that you are.

  Moreover, it is more preferable that the above-mentioned protrusion hole is provided outside the reaction gas manifold or the refrigerant manifold. The outer portion of the manifold is low in rigidity as much as the manifold is formed, and is easily bent due to the influence of external force. In this regard, according to the present invention, it is possible to suppress short-circuiting by forming the insulating layer on the portion that is easily contacted.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress effectively that the short circuit between separators arises in a flat metal type fuel cell.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 9 show an embodiment of the present invention. The separator 20 of the fuel cell 1 according to the present invention includes a resin frame, a set of two metal plates sandwiching the resin frame, and an adhesive member that bonds the metal plate and the resin frame. Further, the metal flat plate is provided with a protruding hole for causing a part of the heat-pressed adhesive member to protrude to the back side of the metal flat plate to form an insulating layer. Hereinafter, the overall configuration of the fuel cell 1 will be described first, and then the separator 20 and the like constituting the fuel cell 1 will be described.

  Incidentally, the fuel cell 1 of the present embodiment is applied to, for example, an in-vehicle power generation system. In this case, the fuel cell 1 is housed in a fuel cell case (not shown) and mounted on a vehicle. However, the fuel cell 1 according to the present invention can be used by being mounted on various moving bodies (for example, robots, ships, airplanes, trains, etc.) other than fuel cell vehicles, and buildings (for example, houses, buildings, factories). Etc.) can also be applied to stationary power generation systems used as power generation facilities.

  As shown in FIG. 1, the fuel cell 1 has a stack structure in which a large number of single cells (unit cells) 2 are stacked. As shown in FIG. 2, the single cell 2 includes a joined body 10 including an electrolyte membrane 11 a and an electrode 11 b and a separator 20 disposed so as to sandwich the joined body 10 from both sides. Further, a cover plate 30, a terminal plate 40 with an output terminal, an insulating plate 50, and an end plate 60 are sequentially provided on the outer side of the single cell 2 positioned at both ends of the cell stack in which the single cells 2 are stacked. Are stacked. The end plates 60 at both ends are joined to the end portions of the tension plate 70 by bolts or the like. Thereby, the whole laminated body of the fuel cell 1 is fastened in a state where a pressing force is applied in the stacking direction.

  The fuel cell 1 configured by the single cell 2 includes a plurality of types such as a phosphoric acid type, but the fuel cell 1 according to the present embodiment is a solid polymer electrolyte type suitable for in-vehicle use or stationary use. As the joined body 10, a membrane / electrode assembly (MEA: Membrane Electrode Assembly) in which an electrode catalyst layer such as platinum is arranged on both surfaces of an electrolyte (solid polymer membrane) made of an ion exchange membrane, or on the catalyst layer Further, a membrane / electrode / diffusion layer assembly (MEGA) provided with a gas diffusion layer can be used.

  As shown in FIG. 1, the fuel cell 1 is connected to a fuel gas piping system 3, an oxidizing gas piping system 4, and a refrigerant piping system 5. The fuel cell 1 is connected to a power system, a control device, and the like (not shown). The supply and discharge of the reaction gas (oxidizing gas and fuel gas) to the fuel cell 1 is performed by the fuel gas piping system 3 and the oxidizing gas piping system 4. Electric power is generated in the single cell 2 of the fuel cell 1 by supplying the reaction gas. The electric power generated by the fuel cell 1 is charged / discharged by the electric power system and supplied to a vehicle-mounted device (not shown). Further, supply and discharge of the refrigerant for adjusting the temperature of the fuel cell 1 are performed by the refrigerant piping system 5. Further, the piping of the gas piping system and the refrigerant piping system extends through the fuel cell case (not shown) and is connected to, for example, the end plate 60.

  As shown in FIGS. 2 and 3A, the joined body 10 is formed in a substantially flat plate shape as a whole, and a catalyst layer 11b for a pair of electrodes (air electrode and fuel electrode) on both surfaces of the electrolyte membrane 11a. , A pair of diffusion layers 12 disposed so as to sandwich the power generation unit 11 from both sides, and a seal unit 13 provided at the peripheral edge of the joined body 10 so as to surround the power generation unit 11. And.

  The diffusion layer 12 has a large number of transmission holes, and is formed of, for example, porous carbon paper, carbon cloth, or the like. The seal portion 13 is formed of, for example, a resin material such as silicon rubber, butyl rubber, or fluorine rubber, and is formed so that a gas manifold 13a for supplying and discharging reaction gas penetrates in the stacking direction. An internal gas flow path for supplying the reaction gas to the air electrode and the fuel electrode of each assembly 10 by the gas manifold 13a provided in the seal portion 13 or gas manifolds 21a and 22a provided in the separator 20 described later. Is formed. The seal portion 13 is formed with a refrigerant manifold 13b for supplying and discharging refrigerant to and from a refrigerant flow passage portion 23b of the separator 20 described later at a position different from the gas manifold 13a.

  As shown in FIGS. 2 and 3B, the separator 20 includes an anode side plate 21 made of a metal flat plate facing the fuel electrode (anode) side surface of the assembly 10, and an air electrode (cathode) of the assembly 10. ) Side cathode surface plate 22 made of a metal flat plate, and a resin frame 23 disposed between the anode side plate 21 and the cathode side plate 22. FIG. 3 only schematically shows the configuration of the single cell 2, and the shapes of the plates 21, 22, the resin frame 23, and the joined body 10 are also schematic. These actual shapes are elongated as shown in FIG. 4 and the like (see FIG. 4 and the like).

  The anode side plate 21 and the cathode side plate 22 are flat thin plate materials, and are formed of, for example, a metal flat plate whose surface is plated to prevent corrosion. As the material of the metal flat plate, for example, titanium, titanium alloy, stainless steel, or the like can be used.

  The resin frame 23 is, for example, a laminate resin having an adhesive layer, and is bonded by heating and bonded to the plates 21 and 22. In the case of the single cell 2 of the present embodiment, the heat-soluble adhesive film 24 is melted by, for example, hot pressing, and functions as an adhesive member that forms a seal portion between the resin frame 23 and the plates 21 and 22. (Refer to FIG. 7 and the like). Further, the resin frame 23 has a frame shape having a predetermined frame width (see FIG. 5), and an area inside the frame portion serves as a refrigerant flow path portion 25 for flowing a refrigerant (for example, cooling water). (See FIG. 7).

  A plurality of protrusions 28 are formed on a plate constituting the separator 20, for example, an anode side plate 21 by press working. These protrusions 28 protrude toward the opposite cathode side plate 22 and function as spacers between the cathode side plate 22 and form the above-described refrigerant flow path portion 25 (see FIG. 6 and the like).

  In the present embodiment, the refrigerant flow path portion 25 is formed using such protrusions 28. However, the present invention is not limited to this. For example, a porous body is provided between the anode side plate 21 and the cathode side plate 22. It is also possible to form a refrigerant flow path by interposing. Although not particularly illustrated, the porous body has, for example, fine pores, and can pass a fluid such as cooling water. As the porous body in this case, a material that does not deform even when heated during hot pressing is used.

  Further, at positions corresponding to the resin frame 23 and the anode side plate 21 and the cathode side plate 22 described above, an oxidizing gas inlet side manifold 15a, an oxidizing gas outlet side manifold 15b, a hydrogen gas inlet side manifold 16a, A hydrogen gas outlet manifold 16b, a refrigerant (cooling water) inlet manifold 17a, and a refrigerant (cooling water) outlet manifold 17b are provided (see FIGS. 4 to 6). Among these, the hydrogen gas manifolds 16a and 16b and the refrigerant manifolds 17a and 17b are formed at both longitudinal ends of the plates 21 and 22 and the resin frame 23 (see FIG. 4 and the like). Further, the inlet side manifold 15a and the outlet side manifold 15b of the oxidizing gas are formed so that a plurality thereof are arranged along the long sides on both sides in the longitudinal direction (see FIG. 4 and the like). Similarly to these, the seal portion 13 of the joined body 10 is also formed with oxidizing gas manifolds 15a and 15b, hydrogen gas manifolds 16a and 16b, and refrigerant manifolds 17a and 17b (see FIG. 3).

  As described above, the fuel cell 1 according to the present embodiment is a so-called flat metal type fuel cell in which the resin frame 23 is sandwiched between the metal flat plates 21 and 22 (see FIG. 7 and the like).

  Here, in the present embodiment, each of the anode side plate 21 and the cathode side plate 22 is a bite for causing a part of the adhesive film 24 to protrude to the back side of the anode side plate 21 or the cathode side plate 22. An outlet hole 26 is provided. In this case, a part of the adhesive film 24 softened during the thermocompression bonding protrudes from the protrusion hole 26 and wraps around the back side of the plate 21 (22), and solidifies to form an electrical insulating layer. In the separator 20 having such a structure, the insulating film can be formed by melting the adhesive film 24 into the back side of the plate 21 (22).

  Such a protrusion hole 26 will be described below with a specific example. That is, for example, in the cathode side plate 22, protrusion holes 26 are formed at respective positions near the outer peripheral portion indicated by an ellipse in FIG. 8A (see FIG. 8B). In this case, each protrusion hole 26 is formed in the vicinity of a portion where adjacent separators can come into contact with each other to cause a short circuit.

  That is, in the fuel cell 1 having a structure in which the gasket 27 is sandwiched between adjacent separators 20 ′ and stacked, for example, when the operation of the fuel cell 1 is continued under a high temperature condition exceeding 80 ° C., Rigidity may be affected by the pressure in the stacking direction. At this time, as shown in FIG. 10, the vicinity of the end of the separator 20 ′ is bent, and adjacent separators 20 ′ may come into contact with each other to cause a short circuit (see FIG. 10).

  In this respect, in the separator 20 of this embodiment, since the insulating layer is formed by the adhesive film 24 that protrudes from the protrusion hole 26 to the back side of the cathode side plate 22, it is assumed that the separators 20 are in contact with each other. Also, it is possible to avoid an electrical short circuit. That is, not only the adhesive film 24 is used to bond the resin frame 23 and the anode side plate 21 (or the cathode side plate 22), but also a part of the adhesive film 24 further functions as an electrical insulating layer. It is possible to effectively prevent a short circuit from occurring between them. In addition, although the cathode side plate 22 was illustrated and demonstrated here, the structure and effect | action in the other anode side plate 21 are the same as that of what was mentioned above.

  From the viewpoint of preventing short-circuiting between the end portions of the separator 20, the protrusion hole 26 as described above is preferably provided in the outer peripheral portion of the separator or in the vicinity thereof. For example, in the present embodiment, a reactive gas manifold (that is, an oxidizing gas inlet side manifold 15a, an oxidizing gas outlet side manifold 15b, a hydrogen gas inlet side manifold 16a, a hydrogen gas outlet side manifold 16b) or a refrigerant manifold 17a, 17b. (See FIG. 8A). The portions where these manifolds are formed are easy to bend due to the force in the stacking direction, but in this embodiment, the protrusion film 26 is provided outside the particularly easy to bend portion, and the adhesive film 24 is provided at the portion where contact is easy. An insulating layer is formed by the above.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, an arrangement example of the plurality of protrusion holes 26 is indicated by an ellipse (see FIG. 8A), but this is only an example. The object of the present invention is to automatically form an insulating layer on the metal flat plate (the anode side plate 21 and the cathode side plate 22). The number and shape of the protruding holes 26 are the same as those of the separator 20. It is preferable to appropriately change the shape and the viscosity of the adhesive film 24.

It is a block diagram of the fuel cell which concerns on embodiment of this invention. It is sectional drawing which shows the structural example of the single cell which comprises a fuel cell. It is a disassembled perspective view of the conjugate | zygote which comprises a single cell. It is a top view which shows the structural example of the cathode side plate (metal flat plate) which comprises a fuel cell. It is a top view which shows the structural example of the resin frame which comprises a fuel cell. It is a top view which shows the structural example of the anode side plate (metal flat plate) which comprises a fuel cell. It is a side view which shows the structural example of a single cell roughly. (A) is a plan view of a metal flat plate (cathode side plate) showing an arrangement example of protrusion holes for protruding part of the adhesive member, and (B) is an enlarged view of the vicinity of the outer peripheral portion indicated by an ellipse. is there. The left side is a schematic view showing an external force acting in the cell stacking direction in the vicinity of the end of the separator, and the right side is a schematic view showing the end of the separator bent due to the external force. The left side is a schematic view showing an external force acting in the cell stacking direction in the vicinity of the end of the separator, and the right side is a schematic view showing the end of the separator bent due to the external force.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 15a ... oxidizing gas inlet side manifold (reaction gas manifold), 15b ... oxidizing gas outlet side manifold (reaction gas manifold), 16a ... hydrogen gas inlet side manifold (reaction gas manifold), 16b ... hydrogen Gas outlet side manifold (reaction gas manifold), 17a ... Refrigerant inlet side manifold (refrigerant manifold), 17b ... Refrigerant outlet side manifold (refrigerant manifold), 20 ... Separator, 21 ... Anode side plate (metal flat plate), 22 ... cathode side plate (metal flat plate), 23 ... resin frame, 24 ... adhesive film (adhesive member), 25 ... refrigerant flow path, 26 ... hole

Claims (5)

In separators for flat metal fuel cells,
A resin frame, a pair of metal flat plates that sandwich the resin frame, and an adhesive member that bonds the metal flat plate and the resin frame;
The separator is characterized in that the metal flat plate is provided with a protruding hole for forming an insulating layer by causing a part of the heat-pressed adhesive member to protrude to the back side of the metal flat plate.   The separator according to claim 1, wherein the protrusion hole is provided in an outer peripheral portion of the separator.   3. The separator according to claim 2, wherein the protrusion hole is provided in the vicinity of a portion where adjacent separators can come into contact with each other to cause a short circuit.   The separator according to claim 3, wherein the protrusion hole is provided outside the reaction gas manifold or the refrigerant manifold.   The flat metal type fuel cell containing the separator as described in any one of Claim 1 to 4.

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