JP2006324147A - Fuel cell and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent degradation of an end of a catalyst layer arranged at an electrolyte film of a fuel cell. <P>SOLUTION: The fuel cell 1, provided with an electrolyte film 11, and a catalyst layer 12 for an electrode arranged at each side of the catalyst film 11, is further provided with a non-catalyst layer 13 arranged at a non-catalyst-layer formed area of the electrolyte film 11. The non-catalyst layer 13 has a compression ratio nearly identical to that of the catalyst layer 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell and a manufacturing method thereof.

  The fuel cell system includes a fuel cell having an electrolyte membrane and electrode catalyst layers provided on both sides of the electrolyte membrane, and an anode gas is provided on one catalyst layer (anode side electrode) of the fuel cell. The cathode gas is supplied to the other catalyst layer (cathode side electrode) to cause an electrochemical reaction to generate electricity.

During operation of the fuel cell system, moisture is generated due to an electrochemical reaction in the fuel cell. Since the moisture generated in this manner (hereinafter referred to as “product water”) contains deterioration-causing substances such as hydrogen peroxide, the produced water is not removed from the catalyst layer formation region of the electrolyte membrane of the fuel cell. When moving toward the formation region (peripheral edge) and collecting near the end of the catalyst layer, the end of the catalyst layer may be deteriorated. In recent years, as a technique that may solve such a problem, a technique has been proposed in which a sealing material made of silicon rubber or fluorine rubber is provided on the periphery of an electrolyte membrane (see, for example, Patent Document 1).
JP-A-7-220742

  However, since the compression rate of the sealing material employed in the technique described in Patent Document 1 is different from the compression rate of the catalyst layer, a common compressive force is applied to the sealing material and the catalyst layer when the fuel cell is manufactured. When fastened, a gap is formed in the vicinity of the end of the catalyst layer, and the generated water may accumulate in the gap. Therefore, even if the technique described in Patent Document 1 is adopted, it is insufficient to prevent deterioration of the end portion of the catalyst layer.

  An object of the present invention is to prevent deterioration of an end portion of a catalyst layer provided on an electrolyte membrane of a fuel cell.

  In order to achieve the above object, a fuel cell according to the present invention is a fuel cell comprising an electrolyte membrane and a catalyst layer for an electrode provided on both surfaces of the electrolyte membrane, wherein the catalyst layer of the electrolyte membrane is provided. A non-catalytic layer is provided in at least a part of the region that is not provided, and the non-catalytic layer has a compression rate substantially the same as that of the catalyst layer.

  According to such a configuration, since the non-catalyst layer having a compression rate substantially the same as the compression rate of the catalyst layer is provided in at least a part of the catalyst layer non-formation region of the electrolyte membrane, these catalyst layer and non-catalyst layer When a common compressive force is applied to the catalyst layer, it is possible to prevent a gap from being generated near the end of the catalyst layer. Therefore, it is possible to prevent the produced water containing the deterioration factor substance from being collected near the end of the catalyst layer, so that deterioration of the end of the catalyst layer can be effectively prevented, and the durability of the catalyst layer can be improved. Can be improved.

  In the present invention, the “compression ratio” means a change in compressive force acting on the catalyst layer and the non-catalyst layer, and a change in dimension in the direction of the compressive force action of the catalyst layer and the non-catalyst layer corresponding to the change in the compressive force. The term “having approximately the same compressibility as the compressibility of the catalyst layer” means that when the same compressive force as that of the catalyst layer is applied, the contraction in the compressive force acting direction is approximately the same dimension. Means.

  In the fuel cell, the non-catalyst layer preferably has substantially the same thickness as the catalyst layer in a state in which no compressive force is applied, and is further composed of a material excluding the catalyst among the materials constituting the catalyst layer. It is preferred that In addition, the non-catalyst layer can be formed by applying a solution for the non-catalyst layer to the region where the catalyst layer of the electrolyte membrane is not provided by a droplet discharge method and solidifying the solution. Moreover, it is preferable that a non-catalyst layer contains a water-repellent material or a water-impermeable material.

  Further, the fuel cell manufacturing method according to the present invention includes an electrolyte membrane, a catalyst layer provided on both surfaces of the electrolyte membrane, and a catalyst layer provided in at least a part of a region where the catalyst layer of the electrolyte membrane is not formed. And a non-catalytic layer having a compression rate substantially the same as the compression rate of the fuel cell, the method comprising: forming a catalyst layer by applying a material constituting the catalyst layer to the electrolyte membrane and drying it; And a step of forming a non-catalyst layer by applying a material excluding the catalyst out of the material constituting the catalyst layer to the catalyst layer non-formation region of the electrolyte membrane and drying it.

  According to such a method, the application work of the material constituting the catalyst layer and the application work of the material constituting the non-catalyst layer (the material excluding the catalyst among the materials constituting the catalyst layer) are performed substantially simultaneously. Since drying after coating can be performed at the same time, the catalyst layer and the non-catalyst layer can be formed in a short time.

  ADVANTAGE OF THE INVENTION According to this invention, deterioration of the edge part of the catalyst layer provided in the electrolyte membrane of the fuel cell can be prevented effectively.

  Hereinafter, a fuel cell according to an embodiment of the present invention will be described with reference to the drawings. The fuel cell according to the following embodiments is a solid polymer electrolyte type fuel cell suitable for in-vehicle use.

  First, the configuration of the fuel cell 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. The fuel cell 1 includes a stack body 2 in which a plurality of unit cells 10 are stacked. A current collector plate 3 with an output terminal, an insulating plate 4 and an end are provided outside the unit cells 10 located at both ends of the stack body 2. The plates 5 are arranged in this order. A tension plate (not shown) is disposed outside each end plate 5, and these tension plates are bolted to the end plates 5 so that a predetermined compressive force is applied in the stacking direction of the cells 10. It has become.

  Next, the configuration of the unit cell 10 will be described with reference to FIGS. 2 and 3. As shown in FIGS. 2 and 3, the unit cell 10 includes an electrolyte membrane 11, an electrode catalyst layer 12 provided on both surfaces of the electrolyte membrane 11, and a dummy provided in a catalyst layer non-formation region 11 a of the electrolyte membrane 11. The layer 13, a diffusion layer 14 disposed outside the catalyst layer 12, a separator 15 provided with a reaction gas flow path, a seal member 16 that seals between the diffusion layer 14 and the separator 15, and the like.

  The electrolyte membrane 11 is made of an ion exchange membrane made of a solid polymer material. The catalyst layer 12 is a sheet-like molded body on which an electrode catalyst such as platinum or cobalt is supported, and constitutes an anode side electrode and a cathode side electrode. Both the electrolyte membrane 11 and the catalyst layer 12 have a rectangular shape in plan view, and the electrolyte membrane 11 has a larger area than the catalyst layer 12 as shown in FIGS.

  The dummy layer 13 is a non-catalyst layer in the present invention, and prevents the gap from being generated near the end of the catalyst layer 12 during fastening in the manufacture of the fuel cell, thereby protecting the end of the catalyst layer 12. is there. The dummy layer 13 is made of a material excluding the catalyst such as platinum among the materials constituting the catalyst layer 12 and has a thickness substantially the same as the thickness of the catalyst layer 12 in a state where the compressive force is not acting. The compression rate of the catalyst layer 12 is substantially the same. In the present embodiment, the dummy layer 13 is formed by applying and solidifying a predetermined solution to the catalyst layer non-formation region 11a of the electrolyte membrane 11 by a droplet discharge method (inkjet method).

  The diffusion layer 14 is made of a porous material such as carbon paper, and diffuses the reaction gas supplied from the outside of the fuel cell 1 to the catalyst layer 12 via the separator 15 and flows to the catalyst layer 12. . The separator 15 is made of a gas-impermeable conductive material, and a reaction gas channel 15a is formed on the electrode side surface. The separator 15 is provided with a manifold 15b serving as an inlet and an outlet for the reaction gas, and the manifold 15b communicates with the reaction gas channel 15a.

  Next, the manufacturing method of the fuel cell 1 according to the present embodiment will be described with reference to FIG.

  First, the electrolyte membrane 11 is prepared (electrolyte membrane preparation process). Next, a paste-like electrode catalyst slurry is prepared by dispersing platinum-supported carbon powder and Nafion solution in a butyl acetate solvent. Further, a paste-like non-catalyst slurry obtained by removing platinum as a catalyst from the electrode catalyst slurry is prepared (slurry preparation step).

  Next, the electrode catalyst slurry is applied to the central portion of the electrolyte membrane 11, and the non-catalyst slurry is applied to the peripheral portion (catalyst layer non-formation region 11a) of the electrolyte membrane 11, and these electrode catalyst slurry and non-catalyst slurry are dried. Thus, the catalyst layer 12 and the dummy layer are formed (catalyst layer / dummy layer forming step).

  Subsequently, as shown in FIG. 3, carbon paper is bonded onto the catalyst layer 12 and the dummy layer 13 to form the diffusion layer 14 (diffusion layer forming step). Then, the unit cell 10 is configured by sandwiching the laminate composed of the electrolyte membrane 11, the catalyst layer 12, the dummy layer 13, and the diffusion layer 14 with the separator 15 through the seal member 16. Thereafter, a stack body 2 is formed by stacking a plurality of single cells 10, a current collector plate 3, an insulating plate 4 and an end plate 5 are arranged at the end of the stack body 2, and a tension plate is bolted to the end plate 5. By doing so, the fuel cell 1 is obtained.

  In the fuel cell 1 according to the embodiment described above, since the dummy layer 13 having the compression rate substantially the same as the compression rate of the catalyst layer 12 is provided in the catalyst layer non-formation region 11a of the electrolyte membrane 11, these When a common compressive force is applied to the catalyst layer 12 and the dummy layer 13, it is possible to prevent a gap from being generated near the end of the catalyst layer 12. Therefore, it is possible to prevent the produced water containing the deterioration factor substance from being collected in the vicinity of the end portion of the catalyst layer 12, so that deterioration of the end portion of the catalyst layer 12 can be effectively prevented. Durability can be improved.

  Moreover, in the manufacturing method of the fuel cell 1 according to the embodiment described above, the application work of the material constituting the catalyst layer 12 and the material constituting the dummy layer 13 (the catalyst is excluded from the materials constituting the catalyst layer 12). The application operation of the material) can be performed at the same time in a common process, and drying after the application can also be performed at the same time. Therefore, the catalyst layer 12 and the dummy layer 13 can be formed in a short time.

  In the above embodiment, the dummy layer 13 is configured using a non-catalytic slurry (carbon powder and Nafion solution dispersed in a butyl acetate solvent) obtained by removing the catalyst (platinum) from the electrode catalyst slurry. However, the non-catalytic slurry constituting the dummy layer 13 may contain a water-repellent material or a water-impermeable material.

  Examples of water-repellent materials include PTFE (polytetrafluoroethylene), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, A tetrafluoroethylene-ethylene copolymer or the like can be employed.

1 is a perspective view showing a fuel cell according to a first embodiment of the present invention. It is a disassembled perspective view of the single cell which comprises the fuel cell shown in FIG. It is sectional drawing which shows the electrolyte membrane etc. which comprise the single battery shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 11 ... Electrolyte membrane, 11a ... Catalyst layer non-formation area | region, 12 ... Catalyst layer, 13 ... Dummy layer (non-catalyst layer)

Claims (8)

A fuel cell comprising an electrolyte membrane and electrode catalyst layers provided on both surfaces of the electrolyte membrane,
A non-catalytic layer provided in at least a part of a region where the catalyst layer of the electrolyte membrane is not provided;
The non-catalyst layer is a fuel cell having a compression rate substantially the same as the compression rate of the catalyst layer.   2. The fuel cell according to claim 1, wherein the non-catalyst layer is provided in an entire region of the electrolyte membrane where the catalyst layer is not provided.   The fuel cell according to claim 1, wherein the non-catalyst layer has substantially the same thickness as the catalyst layer in a state where no compressive force is applied.   The fuel cell according to any one of claims 1 to 3, wherein the non-catalyst layer is made of a material excluding a catalyst among materials constituting the catalyst layer.   5. The non-catalyst layer is obtained by solidifying a solution for a non-catalyst layer applied by a droplet discharge method in a region of the electrolyte membrane where the catalyst layer is not provided. 6. A fuel cell according to claim 1.   The fuel cell according to any one of claims 1 to 5, wherein the non-catalytic layer includes a water-repellent material.   The fuel cell according to any one of claims 1 to 5, wherein the non-catalytic layer includes an impermeable material. An electrolyte membrane, a catalyst layer provided on both surfaces of the electrolyte membrane, and a compression rate substantially the same as the compression rate of the catalyst layer provided in at least a part of the region of the electrolyte membrane where the catalyst layer is not formed A non-catalytic layer comprising: a fuel cell manufacturing method comprising:
Forming the catalyst layer by applying a material constituting the catalyst layer to the electrolyte membrane and drying;
Forming the non-catalyst layer by applying a material excluding the catalyst from the material constituting the catalyst layer to the catalyst layer non-formation region of the electrolyte membrane and drying;
A method for producing a fuel cell comprising:

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