JP2009193922A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell, constituted by laminating a plurality of single cells, enhancing the sealing properties of a gas flow path, or the like, and which is yet easy to manufacture and is capable of a long-term operation and having high reliability. <P>SOLUTION: The fuel cell, constituted of by laminating a plurality of single cells 8, holds an elastic laminated sealing material 10, which is deformed as it is pushed in a laminating direction, between mutually neighboring separators 6 and 7, or between the separators 6, 7 and gas diffusion layers 4, 5 for sealing a fuel gas flow channel groove 6a, or an oxidant gas flow channel groove 7a. Lip portions 7c of the separators 6, 7 which contact the laminated sealing material 10, is designed as projecting toward the laminated sealing material 10, being narrower than the sealing material 10 in width. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell in which a plurality of single cells are stacked, and more particularly to a fuel cell having improved sealing performance such as a gas flow path.

  A fuel cell is a device in which a catalyst layer is disposed on both surfaces of an electrolyte membrane such as a solid polymer, and fuel and an oxidant are supplied thereto to generate electricity by an electrochemical reaction. For example, in a general polymer electrolyte fuel cell, a catalyst layer made of platinum or a platinum compound and a gas diffusion layer made of porous carbon paper or the like are formed on both sides of a solid polymer membrane formed of an ion exchange membrane. The gas-impermeable separator is laminated with gas flow channel grooves on both sides and cooling water flow channel grooves for supplying cooling water for removing heat generated by power generation. ing. In addition, a seal portion for preventing gas and cooling water from flowing out from a predetermined flow path to the outside is provided between the laminated surfaces of the members.

Here, as a sealing method between the laminated surfaces, a method of melting a thermoplastic polymer having a predetermined shape and adhering each member, and a method of sandwiching an elastic sealing material having a predetermined shape have been proposed (for example, patents). Reference 1).
JP-T-2004-523060

  However, in the method of sandwiching the elastic sealing material according to Patent Document 1, there is a problem that the sealing material moves during the operation of the fuel cell and protrudes from the outer periphery of the separator, so that the sealing performance is deteriorated. It was necessary to take measures such as bonding to the surface of a separator or other member in advance.

  In addition, in order to improve the sealing performance by sandwiching the elastic sealing material, it is necessary to increase the surface pressure acting in the direction of crushing the sealing material, but when the tightening force acting on the entire sealing material is large When the surface pressure acting on the sealing material is relaxed due to the deformation of the sealing material over time, the tightening force is received by the reaction part of the fuel cell, and the surface pressure acting on the reaction part of the fuel cell increases. This is not preferable. Therefore, in order to obtain a sufficient seal surface pressure without applying a large tightening force, it is effective to reduce the area of the sealing material instead of increasing the tightening force. However, in this case, if the width of the sealing material is reduced to, for example, a string shape, there is a problem that handling at the time of attachment becomes difficult.

  In addition, instead of narrowing the width of the sealing material, a method of providing a convex lip on a part of the sealing material and concentrating the surface pressure on this part is conceivable. Therefore, there is a problem that the manufacturing cost increases.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to improve a sealing property such as a gas flow path in a fuel cell in which a plurality of unit cells are stacked, and to manufacture the fuel cell. It is an object of the present invention to provide a highly reliable fuel cell that can be operated for a long time.

  In order to achieve the above object, a fuel cell according to the present invention comprises an electrolyte membrane, a pair of catalyst layers comprising an anode catalyst layer and a cathode catalyst layer disposed so as to sandwich the electrolyte membrane, and the pair of catalyst layers. A pair of gas diffusion layers, which are arranged so as to be sandwiched between the anode gas diffusion layer adjacent to the anode catalyst layer and the cathode gas diffusion layer adjacent to the cathode catalyst layer, and sandwich the pair of gas diffusion layers A gas impermeable anode separator that forms a fuel gas channel groove adjacent to the anode gas diffusion layer and a gas impermeable gas that forms an oxidant gas channel groove adjacent to the cathode gas diffusion layer A plurality of single cells having a separator made of a conductive cathode separator, and a seal for the fuel gas channel groove or the oxidant gas channel groove. Therefore, a fuel cell in which an elastic gas flow path sealing material that is pushed and deformed in the stacking direction is disposed between the separators adjacent to each other or between the separator and the gas diffusion layer. A lip portion that protrudes toward the gas flow path sealing material with a width narrower than the width of the gas flow path sealing material is formed in a portion that contacts the gas flow path sealing material.

  According to the present invention, in a fuel cell in which a plurality of unit cells are stacked, a highly reliable fuel cell that improves the sealing performance of a gas flow path and the like, is easy to manufacture, and can be operated for a long time is provided. be able to.

  Embodiments of the present invention will be described below with reference to the drawings. Here, the same or similar components are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
A first embodiment of a fuel cell according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a partial cross-sectional view showing the structure of the fuel cell stack of the fuel cell of the first embodiment, and FIG. 2 is a partial cross-sectional development view (exploded view) of the fuel cell stack. 3 is a perspective view of the unit cell as seen from the cathode separator surface side, FIG. 4 is a plan view showing the shape of the oxidant gas flow path and the lip portion of the cathode separator, and FIG. 5 is a diagram of the gas manifold in the fuel cell stack. FIG. 6 is a plan view showing a state in which an arrangement is added, and FIG. 6 is a plan view showing a state in which the arrangement of the laminated sealing material is added to the fuel cell stack of FIG.

  A pair of the anode catalyst layer 2 and the cathode catalyst layer 3 are disposed so as to sandwich the polymer film on both surfaces of the solid polymer film 1 which is an electrolyte layer, and the anode catalyst layer 2 and the cathode catalyst layer 3 are sandwiched between them. An anode gas diffusion layer 4 and a cathode gas diffusion layer 5 are disposed. Further, the anode separator 6 having the fuel gas flow channel 6a (FIG. 3) adjacent to the anode gas diffusion layer 4 and the cathode gas diffusion layer 5, the oxidant gas flow channel 7a, and the cooling water flow channel 7d (FIG. 3). And a gas impermeable diffusion layer outer peripheral seal portion 9 is disposed on the outer peripheral portions of the anode gas diffusion layer 4 and the cathode gas diffusion layer 5.

  In the present embodiment, these stacked members are coupled to each other to form a single cell 8, and a plurality of single cells 8 are stacked to form a fuel cell stack.

  The fuel gas channel groove 6a, the oxidant gas channel groove 7a, and the cooling water channel groove 7d are all grooves formed on the surface of the anode separator 6 or the cathode separator 7, and a plurality of single cells 8 are stacked. As a result, each channel is closed.

  As a method for joining the laminated members of the unit cell 8, for example, a method in which a thermoplastic polymer is disposed in a seal range between the members and thermocompression bonded can be considered, but other methods may be used. A laminated seal material 10 is disposed between the laminated seal portions of the single cells 8, that is, between the cathode separator 7 and the diffusion layer outer peripheral seal portion 9.

  Here, as shown in the figure, a thin portion 7b is formed at the end of the cathode separator 7, and a convex lip portion 7c is formed in the thin portion 7b toward the diffusion layer outer peripheral seal portion 9. ing. The laminated sealing material 10 is flat as shown in FIG. 2 in the disassembled state. In the laminated state, the laminated sealing material 10 is pressed against the diffusion layer outer peripheral seal portion 9 by the lip portion 7c as shown in FIG. It is deformed and held in a corresponding concave shape.

  As shown in FIGS. 5 and 6, a gas manifold seal material 13 is inserted between the fuel gas manifolds 11 a and 11 b and the oxidizer and cooling water manifolds 12 a and 12 b and the unit cell 8, The end portion of the lip portion 7c branches and comes into contact with the gas manifold seal material 13 to thereby form a closed space comprising the seal portion of the lip portion 7c and the laminated seal material 10 and the wall surfaces of the gas manifolds 11a, 11b, 12a, 12b. The gas and the cooling water in each gas manifold are configured not to be supplied to other than the necessary gas flow path or cooling water flow path.

  Here, the laminated sealing material 10 is a flat plate-like elastic material that is wider than the lip portion 7c. As a specific example of the material of the laminated sealing material 10, silicone rubber or EPDM with high elution of impurities and high durability can be suitably used, but other materials can be used as long as they are elastic bodies that can realize the required durability and sealing performance. But it ’s okay.

  Further, since the thickness of the cathode separator 7 is about 1 mm to 3 mm in a general polymer electrolyte fuel cell, the thickness of the thin portion 7b is about 0.3 mm to 2 mm, and the height of the lip portion 7c is In addition, it is desirable that the amount of deformation in the thickness direction after tightening in a range in contact with the lip portion 7c of the laminated sealing material 10 is about 20% to 50%. The laminated sealing material 10 has a thickness that does not contact the bottom surface of the thin-walled portion 7b in a range where the thin-walled portion 7b is not in contact with the thin-walled portion 7b and is not sandwiched by the lip portion 7c after tightening. It is desirable that expansion and contraction in the surface direction of the cathode separator 7 is not restricted.

  Next, the operation of the first embodiment having the above configuration will be described. In the first embodiment having the above-described configuration, the laminated sealing material 10 is sandwiched between the lip portions 7c having a narrower width than the laminated sealing material 10 provided in the cathode separator 7, so that the laminated sealing material is used in the use state. 10 is deformed into a concave shape corresponding to the convex shape of the lip 7c, and the laminated sealing material 10 is prevented from moving in the surface direction of the cathode separator 7 during operation of the fuel cell.

  Further, it is possible to apply the necessary surface pressure to the laminated sealing material 10 by reducing the width of the lip portion 7c without increasing the fastening force when fastening the fuel cell stack.

  As described above, in the present embodiment, the thin portion 7b and the lip portion 7c are formed on the cathode separator 7, and the flat laminated sealing material 10 is sandwiched by the lip portion 7c to form the sealing portion, thereby forming the laminated portion. There is no need to take separate measures to prevent the seal material 10 from moving. In addition, by making the laminated sealing material 10 wider than the lip portion 7c, handling at the time of attachment becomes easy, and by making the sectional shape of the laminated sealing material 10 flat, the manufacturing cost can be kept low. In addition, since the sufficient surface pressure is applied to the laminated sealing material 10 by narrowing the width of the lip portion 7c, a fuel cell having a highly reliable sealing structure can be provided.

[Second Embodiment]
A second embodiment of the fuel cell according to the present invention will be described with reference to FIGS. Here, FIG. 7 is a plan view showing the shape of the oxidant gas flow path and the lip portion of the cathode separator of the fuel cell of the second embodiment, and FIG. 8 shows a state in which the arrangement of the laminated sealing material is added to the cathode separator. It is a top view.

  As shown in FIG. 7, in this embodiment, the fuel gas manifold 14, the oxidant gas manifold 15, and the coolant manifold 16 are formed by openings that are formed in the stacking direction formed in the anode separator and the cathode separator 7 that are not shown. The thin wall portion 7b and the lip portion 7c of the cathode separator 7 are formed in a shape surrounding the gas manifolds 14, 15, and 16, respectively. Further, as shown in FIG. 8, the laminated sealing material 10 is a flat elastic material having a width wider than that of the lip portion 7c, and the other configuration is the same as that of the first embodiment.

  In the present embodiment, the fuel gas manifold 14, the oxidant gas manifold 15, and the cooling water manifold 16 are also the first embodiment even in a fuel cell in which the anode separator and the cathode separator are formed by openings that penetrate in the stacking direction. The same effect can be obtained.

[Other Embodiments]
The embodiments described above are merely examples, and the present invention is not limited to these.

  For example, in the first embodiment, the unit cell 8 having the cathode gas diffusion layer 5 and the cathode separator 7 above and below is used as a stack unit, and the stack sealing material 10 is inserted between the unit cells 8. A unit cell is formed by combining the anode gas diffusion layer 4 to the anode separator 6 in FIG. 1, and a thin seal portion and a lip portion are formed in the anode separator 6, and a laminated seal is inserted between adjacent members. It is also possible to connect the separator 6 to the cathode separator 7, form a thin portion and a lip portion on the surface of the cathode separator 7 or the anode separator 6, and insert a laminated seal between the separators.

  FIG. 9 shows an example of the shapes of the anode separator 6 and the gas flow path 6a of the anode separator, the thin wall portion 6b, and the lip portion 6c when the seal structure of the present invention is applied to the seal portion between the members adjacent to the anode separator. 10 is a plan view showing the gas flow path of the cathode separator 7 when the seal structure of the present invention is applied to the seal portion of the anode separator 6 adjacent to the cathode separator 7 and the cooling formed on the back surface. It is the top view which showed the example of the shape of the water flow path 7d, the thin part 7e by the side of a cooling water flow path, and the lip part 7f by the side of a cooling water flow path. The same effect as in the first embodiment can be obtained by inserting a flat laminated sealing material having a width wider than that of the lip portion into each thin portion.

  In addition, after applying the seal structure of the present invention to each separator surface without constituting the single cell 8, or after bonding a plurality of single cells without using the seal structure of the present invention, the plurality of single cells are stacked. It is also possible to apply the seal structure of the present invention only to the laminated surface.

  Furthermore, the cross-sectional shape of the laminated sealing material 10 is not limited to a flat plate shape, and for example, a recess 10a corresponding to the lip portion 7c may be provided as shown in FIG. In this case, the depth of the recess 10a in the released state (the state before the laminated sealing material 10 is pushed and deformed in the laminating direction) shown in FIG. 11 is assumed to be shallower than the protruding height of the lip portion 7c.

  As shown in FIG. 12, the stress is concentrated in a range in contact with the lip portion 7c after tightening. As a result, the manufacturing cost of the laminated sealing material increases, but otherwise, the same effect as that of the first embodiment can be obtained, and the workability of the assembly can be improved.

1 is a partial cross-sectional view showing a structure of a fuel cell stack according to a first embodiment of a fuel cell according to the present invention. FIG. 2 is a partial cross-sectional development view of the fuel cell stack of FIG. 1. The perspective view which looked at the cell of FIG. 1 from the cathode separator surface side. The top view which shows the shape of the oxidizing gas flow path and lip | rip part of the cathode separator of FIG. The top view which shows the state which added arrangement | positioning of the gas manifold to the fuel cell laminated body of FIG. The top view which shows the state which added the arrangement | positioning of the laminated sealing material to the fuel cell laminated body of FIG. The top view which shows the shape of the oxidizing gas flow path and lip | rip part of the cathode separator of 2nd Embodiment of the fuel cell which concerns on this invention. The top view which shows the state which added the arrangement | positioning of the lamination | stacking sealing material to the cathode separator of FIG. The top view which shows the example of the anode separator to which the seal structure which concerns on this invention is applied. The top view which looked at the example of the cathode separator to which the seal structure concerning the present invention was applied from the cooling water channel side. The partial cross-section expanded view which shows the fuel cell laminated body of other embodiment of the fuel cell which concerns on this invention. The fragmentary sectional view showing the assembly state of the fuel cell laminated body of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid polymer membrane 2 ... Anode catalyst layer 3 ... Cathode catalyst layer 4 ... Anode gas diffusion layer 5 ... Cathode gas diffusion layer 6 .... Anode separator 6a ... Fuel gas flow path (fuel gas flow path groove)
6b ··· Anode separator thin portion 6c ··· Anode separator lip 7 ··· Cathode separator 7a ··· Oxidant gas flow path (oxidant gas flow path groove)
7b... Thin portion 7c of the cathode separator... Lip portion 7d of the cathode separator... Cooling water channel (cooling water channel groove) formed on the back surface of the cathode separator
7e... Thin portion 7f on cathode coolant flow path side of cathode separator... Lip 8 on cathode separator coolant flow path side... Cell 9. -Laminated seal material 10a ... depression 11a ... fuel gas manifold 11b ... fuel gas manifold 12a ... oxidant and cooling water manifold 12b ... oxidant and cooling water manifold 13 ... gas manifold Seal material 14... Fuel gas manifold 15 formed on the separator 15... Oxidant gas manifold 16 formed on the separator 16... Cooling water manifold formed on the separator

Claims (6)

An electrolyte membrane;
A pair of catalyst layers comprising an anode catalyst layer and a cathode catalyst layer disposed so as to sandwich the electrolyte membrane;
A pair of gas diffusion layers arranged so as to sandwich the pair of catalyst layers, the anode gas diffusion layer adjacent to the anode catalyst layer, and the cathode gas diffusion layer adjacent to the cathode catalyst layer;
A gas-impermeable anode separator that is disposed so as to sandwich the pair of gas diffusion layers and forms a fuel gas channel groove adjacent to the anode gas diffusion layer; and an oxidant gas adjacent to the cathode gas diffusion layer A separator comprising a gas impermeable cathode separator that forms a flow channel groove;
A plurality of unit cells having
For sealing the fuel gas flow channel groove or the oxidant gas flow channel groove, an elastic gas flow that is deformed by being pushed in the stacking direction between the separators adjacent to each other or between the separator and the gas diffusion layer. A fuel cell in which a road seal material is disposed,
A lip portion protruding toward the gas flow path sealing material with a width narrower than the width of the gas flow path sealing material is formed in a portion of the separator that is in contact with the gas flow path sealing material.
A fuel cell. A fuel gas manifold that extends in the stacking direction and communicates with the fuel gas channel groove of each of the unit cells, and an oxidant gas manifold that extends in the stacking direction and communicates with the oxidant gas channel groove of each of the unit cells. And
The fuel gas manifold and the oxidant gas manifold are airtightly arranged at the end of each of the plurality of unit cells stacked via a manifold seal material, and have a lip portion protruding toward the gas flow path seal material. The manifold seal material is disposed in contact with the manifold seal material,
The fuel cell according to claim 1. A cooling water passage groove is formed on the surface of the separator not adjacent to the gas diffusion layer;
In order to seal the cooling water flow channel groove, an elastic cooling water flow channel sealing material that is pushed and deformed between the separators adjacent to each other is arranged.
A lip portion protruding toward the cooling water flow path sealing material with a width narrower than a width of the cooling water flow path sealing material is formed in a portion of the separator that is in contact with the cooling water flow path sealing material;
The fuel cell according to claim 1. A fuel gas manifold that extends in the stacking direction and communicates with a fuel gas passage groove of each of the unit cells; an oxidant gas manifold that extends in the stacking direction and communicates with an oxidant gas channel groove of each of the unit cells; and A cooling water manifold that extends in the stacking direction and communicates with the cooling water channel grooves of each of the unit cells;
The fuel gas manifold, the oxidant gas manifold, and the cooling water manifold are arranged in an airtight or liquid-tight manner via a manifold seal material at each end of the plurality of stacked unit cells, and the gas flow path seal material or The lip portion protruding toward the cooling water flow path seal material and the manifold seal material are disposed in contact with each other;
The fuel cell according to claim 3.   The fuel according to any one of claims 1 to 4, wherein the separator in contact with the gas flow path sealing material is formed with a thin portion for accommodating the gas flow path sealing material. battery.   The portion of the gas flow path seal material that contacts the lip portion is formed with a recess shallower than the protruding height of the lip portion in a released state before being deformed by being pushed in the stacking direction. The fuel cell according to any one of claims 1 to 5.

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