JP5267792B2 - Manufacturing method of electrolyte membrane for fuel cell - Google Patents

Description

  The present invention relates to a method for producing an electrolyte membrane for a fuel cell. More specifically, the present invention relates to a method for producing an electrolyte membrane for a fuel cell including a protective film for protecting and reinforcing the electrolyte membrane.

The electrolyte membrane for the fuel cell is an important member that determines the quality of the power generation performance of the fuel cell in combination with the catalyst layer. Therefore, even if the peripheral portion is damaged, the performance of the fuel cell is deteriorated, and the durability may be deteriorated due to the damage.
Furthermore, the electrolyte membrane for fuel cells is a thin film, weak in strength, and damaged from an adjacent layer such as a gas diffusion layer (more specifically, carbon fluff, which is mainly the material of the gas diffusion layer). easy.
Therefore, Patent Literature 1 presents a method of preparing two frame-shaped protective films, sandwiching each frame portion with the periphery of the electrolyte membrane via an adhesive, and protecting the periphery of the electrolyte membrane, Further, Patent Document 2, after forming the electrolyte film to a carrier film, a catalyst layer was formed on the electrolyte membrane, the catalyst layer is joined to a frame shape protective film along the frame in the periphery thereon, the electrolyte membrane A method for protecting the periphery is presented.
JP 2007-250249 A Special table 2007-533088 gazette

However, according to the method of Patent Document 1, since the protective film rises at the peripheral edge of the electrolyte membrane, the undulation surface state in which the electrolyte membrane with the protective film is recessed from the peripheral portion toward the central portion. become. When the catalyst ink is applied to the electrolyte membrane with a protective film in such a surface state to form a catalyst layer, the application surface is not flat, so that a smooth application operation becomes difficult. In particular, in a mass production line [for example, a roll-to-roll line], coating using a coating means such as a squeegee becomes even more difficult.
In addition , a fuel cell stacks a plurality of single cells to obtain a desired power generation performance. When the electrolyte membrane with a protective film is in an unduration state, a catalyst layer and a diffusion layer are sequentially formed on both sides of the electrolyte membrane. In addition, it becomes difficult to apply a desired surface pressure in the plane of the unit cell in which the separators are stacked, and the catalyst layer, the diffusion layer, and the separator are not preferably in close contact with each other, causing unnecessary internal resistance and voltage drop. The desired power generation performance cannot be exhibited. Furthermore, even if the stack is fastened, an extremely strong load is applied to the outer peripheral portion of the fuel cell, which may promote deterioration of the stack.

Further , according to the method of Patent Document 2, when the catalyst layer and the protective film are overlaid, accurate alignment is required between them, and the joining operation of the catalyst layer and the protective film becomes complicated. Moreover , even if both are suitably overlapped by the method of FIG. 1 and FIG. 2 of Patent Document 2, the catalyst layer in the overlapped portion cannot generate power, and the catalyst performance can be maximized. Disappear. In particular, the platinum catalyst typically used in the catalyst layer should be used as efficiently as possible because platinum is an expensive metal. However, according to this method, the material cost for power generation performance is increased. End up. In addition , it is difficult to apply a desired surface pressure in the plane. Furthermore, even if both are suitably overlapped by the method of FIG. 3 of Patent Document 2, since the edge portion of the diffusion layer is on the inner side of the protective film, the electrolyte membrane is easily damaged.

  The present invention provides an electrolyte membrane structure in which an in-plane of an electrolyte membrane is smooth while including a protective film, and the protection for an electrolyte membrane that can make maximum use of catalyst ink applied to the electrolyte membrane It aims at providing the fuel cell containing a film.

(Aspect of the Invention)
Hereinafter, embodiments of the invention will be shown and described.
(1) A bonding step of bonding a frame-shaped protective film to a carrier film to produce a film assembly having a recess, and an application step of applying an electrolyte solution to the surface including the recess of the film assembly, An embodiment in which the applied electrolyte solution is dried, and the protective film is formed in an electrolyte membrane having a T-shaped cross section on both sides of the T-shaped cross section and in a space between the T-shaped cross section and the carrier film surface. A method for producing an electrolyte membrane for a fuel cell, comprising: a drying step of forming the electrolyte membrane structure of claim 1 (claim 1) .

  According to the method for manufacturing an electrolyte membrane for a fuel cell described in this section, the protective film is formed on the electrolyte membrane having a T-shaped cross section on both sides of the T-shaped cross section and between the T-shaped cross section and the carrier film surface. The formed electrolyte membrane structure can be formed. This electrolyte membrane structure can provide an electrolyte membrane (cross-sectional T-shape) reinforced by a protective film in which the upper surface of the electrolyte membrane having a T-shaped cross-section is flat and parallel to the carrier film surface.

In addition , by the method for producing an electrolyte membrane for a fuel cell described in this section, two bodies of an electrolyte membrane structure with a protective film carried on a carrier film are separately produced, and the carrier film is peeled from each structure, Cross-section cross-sections with approximately the same surface dimensions as the outer periphery of the frame-shaped protective film on both sides of the anode and cathode by joining the coated surfaces of the T-shaped electrolyte membrane back to back (so as to have a symmetrical structure) An electrolyte membrane with a protective film can be produced.

The electrolyte membrane with a protective film thus obtained has an increased membrane strength and is not easily damaged from the outside. Also, the electrolyte membrane is large surface dimensions and the anode and cathode sides of the surface of the electrolyte membrane flat and parallel with each other. As a result, the effective area that is excellent in durability and contributes to power generation performance is widened. And since the application | coating to the electrolyte membrane of catalyst ink becomes smooth, mass productivity improves. Then, the single cells are preferably brought into conductive contact with each other, and thus it is possible to provide a fuel cell excellent in electrical conductivity between the single cells.

  In the bonding process, a frame-shaped protective film is bonded to the carrier film, and a pressure-sensitive adhesive (adhesive) is applied between the carrier film and the frame-shaped protective film when producing a film assembly having a recess. It is preferable to do. The pressure-sensitive adhesive is preferably an acrylic fine pressure-sensitive adhesive, for example. However, the pressure-sensitive adhesive is not limited to this, and a material made of a thermoplastic resin pressure-sensitive adhesive may be applied.

  As described above, the drying process may be natural drying, but in consideration of mass productivity, hot air drying is preferable.

By forming a catalyst layer on both sides of the obtained electrolyte with a protective film by the method for producing an electrolyte membrane for a fuel cell described in this section, a membrane electrode assembly with a protective film (“MEA”) A gas diffusion layer (abbreviated as “GDL”) on the catalyst layer, and a membrane electrode gas diffusion layer assembly with protective film (Membrane Electrode GDL Assembly: “ Abbreviated as “MEGA”). Further , a half electrolyte membrane with a protective film carried on a carrier film (in this specification, “half” means half of an electrolyte membrane structure when the electrolyte membrane is finally used in a fuel cell ( The same applies to the following), a half electrolyte membrane with a protective film, and further, a half MEA with a protective film supported on a carrier film by forming a catalyst layer on these electrolyte membranes, and a half with a protective film An MEA can be provided. By joining these back to back, an electrolyte membrane with a protective film carried on a carrier film, a half electrolyte membrane with a protective film, an MEA with a protective film carried on a carrier film, or an MEA with a protective film can be provided, Furthermore, GDL is formed on a catalyst layer, and MEGA with a protective film supported on a carrier film, or MEGA with a protective film can be provided.

(2) Prior to the bonding step described in (1 ) above, a first coating step of applying an electrolyte solution to the carrier film to form a carrier film coated with the electrolyte solution;
Drying the coated electrolyte solution, and a first drying step of forming an electrolyte membrane,
The coated surface of the carrier film electrolyte membrane is formed, and the bonding step of bonding the frame-shaped protective film to produce a film assembly having a recess,
A second coating step of coating the electrolyte solution on the surface including the concave portion of the film assembly, as a coating step according to the above (1) ,
Drying the coated electrolyte solution, the cross-section H-shaped electrolyte membrane, to form the electrolyte membrane structure embodiments the protective film is formed on both sides the space of cross H-state, the (1 A second drying step as a drying step according to item) ,
(1) A method for producing an electrolyte membrane for a fuel cell according to the above item (2).

  According to the method for manufacturing an electrolyte membrane for a fuel cell described in this section, the protective film is formed on the electrolyte membrane having an H-shaped cross section on both side spaces having a H-shaped cross-section (the H-shaped sideways in FIG. 7). The formed electrolyte membrane structure can be formed. Provided by this electrolyte membrane structure is an electrolyte membrane (H-shaped cross-section) reinforced by a protective film so that the upper and lower surfaces of the electrolyte membrane having an H-shaped cross-section are flat and parallel, and further parallel to the carrier film surface. Can do.

Further, as in the case of the above item (1), the film strength is increased and it is difficult to be damaged from the outside. Also, the electrolyte membrane is large surface dimensions and the anode and cathode sides of the surface of the electrolyte membrane flat and parallel with each other. As a result, the effective area that is excellent in durability and contributes to power generation performance is widened. And since the application | coating to the electrolyte membrane of catalyst ink becomes smooth, mass productivity improves. Then, the single cells are preferably brought into conductive contact with each other, and thus it is possible to provide a fuel cell excellent in electrical conductivity between the single cells.

  Further, as in the case of (1), MEA or MEGA can be provided by adding a catalyst layer, or a catalyst layer and a gas diffusion layer to the electrolyte membrane reinforced by the protective film.

  Since the drying step is the same as that in the item (1), description thereof is omitted.

(3) After the drying step described in the above item (1) or the second drying step described in the above item (2) , the method includes a peeling step for peeling the carrier film from the film assembly (1). Item (2) The method for producing an electrolyte membrane for a fuel cell according to Item (2 ) .

In the manufacturing process of the fuel cell, after completion of peeling of the carrier film according to this item, in the item (1), an electrolyte membrane with a protective film or a half electrolyte membrane in which the electrolyte membrane part having a T-shaped cross section is protected and reinforced with a protective film On the other hand, in the item (2), an electrolyte membrane with a protective film in which an electrolyte membrane portion having an H-shaped cross section is protected and reinforced with a protective film is produced.
Incidentally, after peeling before or carrier film in accordance with the book section, to align the entire surface dimension precision, as appropriate sides or it may be cut all sides. Moreover , when transporting, temporarily storing, or selling the electrolyte membrane, MEA, or MEGA alone with a protective film, it is preferable to handle the carrier film in a state that does not peel from the electrolyte membrane with the protective film.

(4) above (1) or (2) the protective film with a fuel cell electrolyte membrane formed on the carrier film obtained by the production method of a fuel cell electrolyte membrane according to claim (Claim 4).
(5) above (3) protective film with a fuel cell electrolyte membrane obtained by the method for manufacturing a fuel cell electrolyte membrane according to claim (Claim 5).

The description of the above items (4) and (5) is omitted because it overlaps with the above description.

(6) A polymer electrolyte fuel cell or a direct methanol fuel cell comprising the electrolyte membrane for a fuel cell with a protective film according to (4) or (5).

  This section exemplifies a fuel cell to which the electrolyte membrane for a fuel cell with a protective film obtained by the section (4) or (5) can be applied. By forming a catalyst layer, a necessary water repellent layer, a gas diffusion layer, and a separator with a flow path in order on both surfaces of the electrolyte membrane for a fuel cell with a protective film, a single cell is formed, and by stacking and fastening it, A polymer electrolyte fuel cell or a direct methanol fuel cell can be produced.

  The method for producing an electrolyte membrane for a fuel cell according to the present invention can provide an electrolyte membrane structure in which both surfaces of the electrolyte membrane are parallel while including a protective film, and the catalyst is applied to the electrolyte membrane. It is possible to provide a fuel cell including a protective film for an electrolyte membrane that can maximize the catalytic performance of the ink. In particular, according to the manufacturing method, since the catalyst ink can be smoothly applied to the electrolyte membrane, the manufacturing method enables the fuel cell (unit cell) to be mass-produced on a roll-to-roll mass production line. In the battery production line, significant cost reduction can be achieved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIGS. 1 to 3 and FIGS. 4 to 7 are shown for explaining the embodiments of the invention, that is, the first embodiment and the second embodiment. The attached part shows the same thing or the same material.

<First Embodiment>
The first embodiment includes a joining process, a coating process, and a drying process. The first embodiment will be described with reference to FIGS. 1 to 3.

Joining step: This step will be described below with reference to FIG.
In this step, first, the carrier film 1 is prepared. The carrier film 1 is preferably made of ETFE (ethylene / tetrafluoroethylene copolymer) having suitable strength and flexibility as a carrier. In a roll-to-roll mass production line, a carrier film wound around a roll is wound around the roll. The carrier film needs not only strength but also flexibility. From this viewpoint, the thickness is preferably about 15 μm to 50 μm, for example. The roll width may be determined depending on how many unit cells are taken in consideration of the machining margin in the width direction. Next, a frame-shaped protective film 2 is prepared. Protective film 2 electrolyte membrane 4 (see FIGS. 2 and 3) because it is intended to particularly protect and reinforce the peripheral portion of the strength is high also conveys used in a similar roll-to-roll mass production line and the carrier film 1 tends Those having such flexibility are preferred. From this viewpoint, for example, a film made of PEN (polyethylene naphthalate) often used as an engineering plastic and having a thickness of about 5 μm to 25 μm is preferable. The frame width of the frame-shaped protective film 2 is preferably as narrow as possible from the viewpoint of not hindering the proton conductivity of the electrolyte membrane that affects the power generation performance of the unit cell, but it is the electrolyte membrane 4 that is the original purpose. From the viewpoint of protecting / reinforcing, it is preferable that there is a certain width. For example, it may be determined in consideration of the catalyst layer size of the unit cell structure, the separator size, and the like. The surface dimension of the carrier film 1 is equal to or larger than the outer peripheral dimension of the frame-shaped protective film 2. From the viewpoint of reducing the material cost, it is desirable that the two are the same. However, in manufacturing (mass production), since the precise alignment is essential, the surface dimensions of the carrier film 1 are protected in a frame shape. It is desirable that the film 2 is formed to be slightly larger than the outer peripheral dimension, and is finally cut and adjusted appropriately by cutting or punching so as to have a desired unit cell surface dimension.

  When the prepared carrier film 1 and the frame-shaped film 2 are bonded to each other, an ultra-thin acrylic layer is formed by applying an acrylic fine pressure-sensitive adhesive to the surface of the frame-shaped film 2 on the bonding surface by several μm. It is preferable. After bonding them together, they are nipped with two rolls or pressed together with a press to join them. In this way, in this step, the film joined body 49 having the recess 3 as illustrated in FIG. 1 is formed.

Application Step: This step will be described with reference to FIG.
In this step, the electrolyte solution 4 is applied to the film bonded body 49 having the recesses 3 formed in the bonding step by a casting method using an application means 5 such as a squeegee, a bar coater, a die coater, a doctor blade, Finally, the electrolyte solution 4 covers the frame (frame) surface 2F of the frame-shaped protective film 2 while filling the concave portion 3, thereby forming a flat coating surface. Since the electrolyte solution 4 has a low viscosity, the electrolyte solution 4 is easily poured into the concave portion 3 by gravity to fill the concave portion 3, and the electrolyte solution 4 overflowing from the concave portion 3 forms the above-described planar coating surface. It will be.
The electrolyte solution 4 is an electrolyte solution made of perfluorosulfonic acid (for example, a polymer having a sulfonic acid group having a Teflon (registered trademark) skeleton) with an electrolyte solution having a concentration of about 10% to 20% using water and ethanol as a solvent. is there. Specific examples of the electrolyte polymer made of perfluorosulfonic acid include Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., and Aciplex (registered trademark) manufactured by Asahi Kasei. Further, warm air of about 100 ° C. to 130 ° C. is sent to the applied electrolyte solution 4 to evaporate moisture and organic solvent components.

  Thus, in the first embodiment, as shown in FIG. 3 (A-A ′ cross-sectional view in FIG. 2), the cross-section is substantially T-shaped with the frame-shaped protective film 2 carried on the carrier film 1. The electrolyte membrane structure 50 made of the electrolyte membrane 4 is manufactured.

  Thereafter, when a fuel cell is manufactured using the electrolyte membrane structure 50, two pairs of electrolyte membrane structures 50 are prepared, the carrier film 1 is peeled off from each of them, and the bottom portions 4B of the substantially T-shaped electrolyte membranes The electrolyte membrane with the protective film can also be produced by bonding by hot pressing so that the two are back to back. Then, a catalyst layer, a necessary water repellent layer, a gas diffusion layer, and a separator are symmetrically formed on both sides of the electrolyte membrane with a protective film by a conventional method to produce a single cell. Thereafter, in order to obtain a desired power, the single cells are stacked, the stack body is fastened, and the fuel cell is manufactured.

  The electrolyte membrane structure 50 alone can be stored, transported, or sold as a half MEA having a catalyst layer formed thereon or as a half MEGA having a gas diffusion layer formed on the half MEA. .

Second Embodiment
The second embodiment includes a first application process, a bonding process, a second application process, and a drying process. The second embodiment will be described with reference to FIGS.

First application step: This step will be described below with reference to FIG.
In this step, an electrolyte solution 6 having the same component as that of the first embodiment is applied to the carrier film 1 made of the same material as that of the first embodiment by a casting method similar to that of the first embodiment, and hot air of about 100 ° C. to 130 ° C. is applied. Then, the water and the organic solvent in the electrolyte solution 6 are evaporated to form a film joined body 98 composed of the carrier film 1 covered with the electrolyte membrane 6.

  Joining process: FIG. 5 shows the film joined body 99 obtained by this process. As can be seen by comparing FIG. 1 and FIG. 7 is bonded onto the film bonded body 98 (FIG. 4). At this time, the recessed part 8 similar to the recessed part 3 of FIG. 1 is formed.

  Second Application Step: FIG. 6 shows a diagram for explaining this step. As can be seen by comparing FIG. 2 and FIG. 6, the first embodiment uses the same method as the application step in the first embodiment. The electrolyte solution 9 having the same components as in the first embodiment is applied by the same casting method as in the first embodiment, and the water and the organic solvent in the electrolyte solution 9 are evaporated with hot air of about 100 ° C. to 130 ° C. The electrolyte membrane structure 100 covered with is formed.

  In this way, according to the second embodiment, the cross-section is substantially H-shaped with the frame-shaped protective film 7 supported on the carrier film 1 as illustrated in FIG. 7 (cross-sectional view along BB ′ in FIG. 5). An electrolyte membrane structure 100 made of an electrolyte membrane 9 having a shape (a horizontal H shape in FIG. 7) is manufactured.

  Thereafter, when a fuel cell is manufactured using the electrolyte membrane structure 100, the carrier film 1 is peeled off to produce an electrolyte membrane with a protective film. Then, a catalyst layer, a necessary water repellent layer, a gas diffusion layer, and a separator are symmetrically formed on both sides of the electrolyte membrane with a protective film by a conventional method to produce a single cell. Thereafter, in order to obtain a desired power, the single cells are stacked and the stack body is fastened to produce a fuel cell.

The second embodiment is summarized as follows with reference to the configuration of the first embodiment.
That is, prior to the bonding step (FIG. 1) of the first embodiment, the first application step (FIG. 4) of applying the electrolyte solution 6 to the carrier film 1 and forming the carrier film 1 covered with the electrolyte solution 6; ,
  A first drying step (FIG. 4) for forming a film assembly 98 including an electrolyte membrane obtained by drying the applied electrolyte solution 6,
  A joining step (FIG. 5) for joining the frame-shaped protective film 7 to the application surface of the film joined body 98 that is the carrier film 1 on which the electrolyte membrane 6 is formed, and producing the film joined body 99 having the recesses 8;
  A second application step (FIG. 6) for applying the electrolyte solution 9 to the surface including the concave portion 8 of the film assembly 99, as in the application step in the first embodiment,
  The applied electrolyte solution 9 is dried to form an electrolyte membrane structure 100 having an aspect in which a protective film 7 is formed in both side spaces with a H-shaped cross section on an electrolyte membrane having an H-shaped cross section. A second drying step (FIG. 6) as a form drying step;
A method for producing an electrolyte membrane for a fuel cell, comprising:

  In addition, as electrolyte membrane structure 100 single-piece | unit, it can also store, convey, or sell as MEA which formed the catalyst layer on it as MEA which further formed the gas diffusion layer on MEA.

In addition , the manufacturing method of the electrolyte membrane for fuel cells which concerns on this invention is not limited to above-described embodiment, Of course, in the range which does not deviate from the summary of this invention, a various change can be added.

  For example, as a modification of the first and second embodiments, in the above-described joining step, a frame-shaped protective film is joined to the carrier film, and then, for example, expanded PTFE (polytetrafluoroethylene) is formed on the protective film. (PTFE in which an electrolyte polymer is filled in a porous membrane) A film may be formed in a frame shape, and then the process may proceed to the next coating step. By forming in this way, the electrolyte membrane structures 50 and 100 can be further reinforced.

As another modification of the first and second embodiments, in the first embodiment, the joining process (FIG. 1) and the coating process (FIG. 2) are repeated a plurality of times to obtain the second embodiment. In that case, the joining step (FIG. 5) and the second coating step (FIG. 6) may be repeated a plurality of times so that the protective film has a multilayer structure. By forming in this way, the electrolyte membrane structures 50 and 100 can be further reinforced.

FIG. 1 is a perspective view for explaining a joining process of the first embodiment. FIG. 2 is a perspective view for explaining a coating process of the first embodiment. FIG. 3 is a cross-sectional view of the electrolyte membrane structure 50 with a protective film manufactured in the first embodiment. FIG. 4 is a perspective view for explaining the first application process of the second embodiment. FIG. 5 is a perspective view for explaining the joining step of the second embodiment. FIG. 6 is a perspective view for explaining a second application process of the second embodiment. FIG. 7 is a cross-sectional view of the electrolyte membrane structure 100 with a protective film manufactured in the second embodiment.

1: carrier film, 2, 7: protective film, 4, 6, 9: electrolyte membrane, 50, 100: electrolyte membrane structure with protective film

Claims (5)

Bonding a frame-shaped protective film to the carrier film, and a bonding process for producing a film assembly having a recess;
An application step of applying an electrolyte solution to the surface including the concave portion of the film assembly;
An embodiment in which the applied electrolyte solution is dried, and the protective film is formed in an electrolyte membrane having a T-shaped cross section on both sides of the T-shaped cross section and in a space between the T-shaped cross section and the carrier film surface. A drying step of forming an electrolyte membrane structure of
The manufacturing method of the electrolyte membrane for fuel cells characterized by the above-mentioned. Prior to the bonding step according to claim 1, a first coating step of applying an electrolyte solution to the carrier film to form a carrier film coated with the electrolyte solution;
Drying the coated electrolyte solution, and a first drying step of forming an electrolyte membrane,
The coated surface of the carrier film electrolyte membrane is formed, and the bonding step of bonding the frame-shaped protective film to produce a film assembly having a recess,
A second coating step of applying an electrolyte solution as a coating step according to claim 1 , on the surface including the concave portion of the film assembly;
The applied electrolyte solution is dried to form an electrolyte membrane structure having an aspect in which the protective film is formed in both side spaces having a H-shaped cross section on an electrolyte membrane having an H-shaped cross section. A second drying step as the described drying step ;
The method for producing an electrolyte membrane for a fuel cell according to claim 1 , comprising: 3. The method according to claim 1 , further comprising a peeling step of peeling the carrier film from the film assembly after the drying step according to claim 1 or the second drying step according to claim 2. A method for producing an electrolyte membrane for a fuel cell.   The electrolyte membrane for fuel cells with a protective film formed in the carrier film obtained by the manufacturing method of the electrolyte membrane for fuel cells of Claim 1 or Claim 2.   The electrolyte membrane for fuel cells with a protective film obtained by the manufacturing method of the electrolyte membrane for fuel cells of Claim 3.

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