JP4438475B2 - Manufacturing method of membrane electrode assembly - Google Patents

Description

  The present invention relates to a method for producing a membrane electrode assembly.

A fuel cell continuously supplies fuel and oxygen from the outside and reacts electrochemically to extract electric energy. Fuel cells have been attracting attention in recent years because environmental problems have become more prominent because they are more efficient and emit less carbon dioxide than other power generation methods.
For example, a polymer electrolyte fuel cell (PEFC) can operate at a low temperature, has a short start-up time, and can be downsized. This polymer electrolyte fuel cell is equipped with a MEA (Membrane Electrode Assembly) having a structure in which a polymer solid electrolyte membrane is sandwiched between an air side electrode and a fuel side electrode, and supplies air (oxygen) to the air side electrode. By supplying a fuel such as methanol or reformed hydrogen to the side electrode, an electrochemical reaction occurs and electric power is generated.
In such a fuel cell, a structure in which the contact area between each electrode and the fuel and air (oxygen) is increased in order to improve the output efficiency of the fuel cell by increasing the reaction efficiency between each electrode and the fuel and air (oxygen). Have been proposed (see, for example, Patent Document 1). In this fuel cell, concavities and convexities are formed in the joined body in which the electrolyte membrane, the anode electrode, and the cathode electrode are joined. In the case of forming the unevenness, the membrane electrode assembly is manufactured by bonding the electrolyte membrane and the cathode electrode on the anode electrode having the unevenness formed in advance by pressing or cutting.

JP 2003-331865 A

However, in the fuel cell having such a structure, since the unevenness is formed in advance on the anode electrode, it is difficult to form the electrolyte membrane along the unevenness. For this reason, the electrolyte membrane is not easily adapted to the unevenness of the anode electrode, and the contact between the anode electrode and the electrolyte membrane cannot be improved. Therefore, the reaction efficiency of the fuel cell cannot be made sufficiently good.

  The objective of this invention is providing the manufacturing method of the membrane electrode assembly which can make the contact of an electrode and an electrolyte membrane favorable.

The method for producing a membrane / electrode assembly of the present invention is a method for producing a membrane / electrode assembly comprising an electrolyte membrane and an electrode formed on the surface of the electrolyte membrane, and an uneven surface formed on the surface of the electrode. On the other hand, a press mold having a shape corresponding to the shape of the concavo-convex surface includes a membrane pressing step of pressing an electrolyte membrane impregnated with an electrolyte material having proton conductivity in a porous membrane.
According to the present invention, when the electrolyte membrane is pressed against the uneven surface of the electrode by the membrane pressing step, the fibers in the electrolyte membrane extend to some extent and follow the uneven surface. Therefore, the electrolyte membrane is well adapted to the uneven surface of the electrode, and the contact between the electrolyte membrane and the electrode is good.
Further, since the electrolyte membrane is configured by impregnating a porous membrane with an electrolyte material in advance, it is not necessary to impregnate the electrolyte material after the membrane pressing step, and the manufacturing process of the membrane electrode assembly is simplified. The

The method for producing a membrane / electrode assembly of the present invention is a method for producing a membrane / electrode assembly comprising an electrolyte membrane and an electrode formed on the surface of the electrolyte membrane, and an uneven surface formed on the surface of the electrode. On the other hand, with a press die having a shape corresponding to the shape of the uneven surface, a membrane pressing step for pressing the porous membrane, and an electrolyte impregnation for forming an electrolyte membrane by impregnating the porous membrane with an electrolyte material having proton conductivity And a process.
According to the present invention, when the porous membrane is pressed against the uneven surface of the electrode by the membrane pressing step, the fibers in the porous film extend to some extent and follow the uneven surface. Thereafter, an electrolyte membrane is formed by impregnating the porous membrane with an electrolyte material in an electrolyte impregnation step.
Since the membrane pressing step is provided, the porous membrane is well adapted to the uneven surface of the electrode, and the contact between the porous membrane and the electrode is good.

In the present invention, it is desirable to provide a vibration step for applying vibration to the porous membrane or the electrolyte membrane simultaneously with the membrane pressing step.
According to the present invention, since the vibration process is provided, the fibers in the porous film or the electrolyte membrane are broken by vibrating the porous film or the electrolyte film in the membrane pressing process, so that the electrode It becomes easy to follow the shape of the uneven surface. In addition, when a porous membrane that is not impregnated with an electrolyte material is pressed on an uneven surface in the membrane pressing step, the fibers in the porous membrane are shortened by the vibration step, and the fiber density is improved and the electrolyte material Since the absorptive power is improved, the porous membrane is satisfactorily impregnated with the electrolyte material in the subsequent electrolyte impregnation step, and the proton conductivity is improved.

In the present invention, it is desirable to provide a shrinking step for shrinking the porous membrane or the electrolyte membrane before the membrane pressing step.
According to this invention, the porous membrane or the electrolyte membrane is contracted in advance by the contraction step before the membrane pressing step. When the membrane pressing step is performed in this state, the contracted porous membrane or electrolyte membrane is deformed along the concavo-convex surface of the electrode while being stretched, and conforms to the concavo-convex surface. Since the porous membrane or the electrolyte membrane is previously shrunk in the shrinking process, the porous film or the electrolyte membrane follows the uneven surface well without being broken in the membrane pressing step. Therefore, breakage of the film in the film pressing process is reliably and reliably prevented, and the yield is improved.

The method for producing a membrane / electrode assembly of the present invention is a method for producing a membrane / electrode assembly comprising an electrolyte membrane and an electrode formed on the surface of the electrolyte membrane, and an uneven surface formed on the surface of the electrode. A porous film forming step for forming a porous film by laminating electrolyte membrane materials for forming an electrolyte film on a fiber, and an electrolyte for impregnating the porous film with an electrolyte material having proton conductivity And an impregnation step.
According to this invention, in the porous membrane forming step, the porous membrane is formed by laminating the fibrous electrolyte membrane material on the uneven surface of the electrode. Thereafter, in the electrolyte impregnation step, the laminated porous membrane is impregnated with an electrolyte material to form an electrolyte membrane having proton conductivity.
Since the electrolyte membrane material is directly laminated on the concavo-convex surface, the porous film is formed to follow the concavo-convex surface of the electrode satisfactorily, and the contact between the two becomes good. In addition, since the electrolyte membrane material is laminated in a fibrous form, the electrolyte material is well absorbed and retained in the electrolyte impregnation step, and the electrolyte membrane material is well impregnated into the porous membrane, so that the proton conductivity of the electrolyte membrane is improved. It becomes good.

In the present invention, it is desirable that the porous membrane forming step includes a spraying step of dissolving the electrolyte membrane material and spraying the dissolved electrolyte membrane material in a fibrous form on the uneven surface.
According to this invention, the electrolyte membrane material is laminated in a fibrous form by spraying the dissolved electrolyte membrane material in the spraying step. Therefore, it is not necessary to previously form the electrolyte membrane material in a fiber shape, and the manufacturing process of the membrane electrode assembly is simplified.

In the present invention, the porous membrane forming step is a spraying step of dispersing the electrolyte membrane material formed in a fiber shape in a solvent and spraying a solution in which the electrolyte membrane material is dispersed in the solvent onto the uneven surface. And an evaporation step for evaporating the solvent in the solution.
According to this invention, the fibrous electrolyte membrane material is laminated on the uneven surface by spraying the solution in which the fibrous electrolyte membrane material is dispersed in the spraying step. Then, a fibrous porous film is formed on the uneven surface of the electrode by evaporating the solvent in the evaporation step.
Since the electrolyte membrane material is dispersed in the solvent, the electrolyte membrane material can be handled as a liquid, spraying on the uneven surface is facilitated, and the handleability of the electrolyte membrane material is improved. In addition, since the electrolyte membrane material is formed in a fiber shape in advance, it is easy to adjust the characteristics of the electrolyte membrane such as the pore diameter and porosity of the porous membrane. Furthermore, since there is no need to dissolve the electrolyte membrane material, no melting means such as heating is required, and the work of the porous membrane forming process is simplified.

In the present invention, it is desirable that the porous film forming step includes a pressing step of pressing the electrolyte membrane material against the uneven surface.
According to the present invention, since the porous film forming step includes a pressing step, the electrolyte membrane material is pressed against the uneven surface to better follow the shape of the uneven surface, and the contact between the two is even better. It becomes.

In the present invention, it is desirable to provide a vibration process for applying vibration to the electrolyte membrane material simultaneously with the pressing process.
According to this invention, since the vibration process is provided, the electrolyte membrane material is vibrated in the pressing process, so that the fibrous electrolyte membrane material is broken and easily follows the shape of the uneven surface of the electrode. Become. In addition, since the fiber density is improved by shortening the fiber for the electrolyte membrane material and the absorbability of the electrolyte material is improved, the porous membrane is well impregnated in the subsequent electrolyte impregnation step, and the proton conductivity is improved. It becomes good.

In the present invention, it is desirable to include a heating step of heating the electrolyte membrane material simultaneously with the pressing step.
According to this invention, since the heating step is provided, the electrolyte membrane material is heated in the pressing step, so that the electrolyte membrane material softens and follows the uneven surface well. Alternatively, when the electrolyte membrane material is dissolved by heating, the fibers adhere well to each other and the configuration of the porous membrane is strengthened, and the contact between the porous membrane and the electrode is further improved.

In the present invention, it is desirable to provide a mixing step of mixing an adhesive with the electrolyte membrane material before the porous membrane forming step.
According to this invention, since the mixing step is provided, when the electrolyte membrane material is laminated on the uneven surface in the porous membrane forming step, the fibrous porous membranes laminated by the adhesive are bonded to each other by the adhesive. . Therefore, the shape of the porous film can be easily maintained and the contact with the electrode can be further improved.

In this invention, it is desirable to provide the adhesive spraying process which sprays an adhesive agent on a porous film after the porous film formation process.
According to this invention, since the adhesive spraying step is provided, after forming the porous film on the uneven surface of the electrode, the adhesive is sprayed on the porous film, and the shape of the porous film on the uneven surface Is maintained well. In addition, since the adhesive reaches the contact surface with the electrode through the porous film and also adheres to the contact surface, the contact between the porous film and the electrode is further improved.

The membrane electrode assembly of the present invention is manufactured by the above-described method for manufacturing a membrane electrode assembly.
According to this invention, since the membrane / electrode assembly is manufactured by the above-described method for manufacturing a membrane / electrode assembly, the same effect as that of the method for manufacturing the above-mentioned membrane / electrode assembly can be obtained. The contact with is good. Accordingly, when the proton conductivity of the electrolyte membrane is exhibited well, the reaction efficiency of the membrane / electrode assembly is improved.

A fuel cell according to the present invention includes the above-described membrane electrode assembly.
According to this invention, since the fuel cell includes the membrane electrode assembly described above, the same effect as that of the membrane electrode assembly can be obtained, and the contact between the electrolyte membrane and the electrode can be improved. The reaction efficiency of the fuel cell becomes good, and the amount of current (output) obtained for a certain volume is improved.

A device according to the present invention includes the fuel cell described above.
According to this invention, since the device includes the above-described fuel cell, the same effect as the above-described fuel cell can be obtained, the contact between the electrolyte membrane and the electrode is good, and the reaction efficiency of the fuel cell is good. It becomes. Thereby, the electric current amount (output) obtained with respect to a fixed volume improves. Thereby, the output obtained in the device is improved.

  According to the method for producing a membrane electrode assembly of the present invention, the contact between the electrolyte membrane and the electrode can be improved, and good proton conductivity can be obtained, and this membrane electrode assembly is applied to, for example, a fuel cell. In such a case, the reaction efficiency can be improved and the output can be improved.

  Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In the second embodiment and later described below, the same reference numerals are given to the same components and components having the same functions as those in the first embodiment described below, and description thereof will be simplified or omitted.

[First embodiment]
FIG. 1 shows a side sectional view of a fuel cell 1 according to the first embodiment of the present invention. In FIG. 1, a fuel cell 1 is a direct methanol fuel cell (DMFC), and a fuel cell 10 is housed in a case 11. In this embodiment, in order to simplify the description, a fuel cell 1 configured by a single fuel cell 10 is illustrated as shown in FIG. 1. Of course, the fuel cell 1 includes the fuel cell 10. A stack structure in which a plurality of sheets are stacked may be used.

The fuel cell 10 includes a polymer solid electrolyte membrane 2 as an electrolyte membrane, an anode electrode 3 and a cathode electrode 4 as electrodes integrally formed on both surfaces of the polymer solid electrolyte membrane 2, and an anode electrode 3 side. The fuel diffusion layer 5 disposed on the cathode electrode 4, the air diffusion layer 6 disposed on the cathode electrode 4 side, and the fuel diffusion layer 5 and the air diffusion layer 6 are provided outside the air diffusion layer 6. And current collectors 7 and 8 for taking out electric energy generated between them. The fuel cell 10 is housed in a case 11 and is sandwiched from both sides of the polymer solid electrolyte membrane 2 by a gasket 12. Thereby, the inside of the case 11 is sealed and separated on the anode electrode 3 side and the cathode electrode 4 side with the polymer solid electrolyte membrane 2 interposed therebetween.
That is, the region between the inner wall of the case 11 and the anode electrode 3 is liquid-tight and serves as a fuel chamber 31 as an anode-side reaction chamber to which fuel is supplied. A region between the inner wall of the case 11 and the cathode electrode 4 is an air chamber 41 as a cathode side reaction chamber to which air is supplied. Note that a methanol (CH ₃ OH) aqueous solution is supplied as the fuel.

  A fuel supply port 111 for supplying fuel to the inside of the case 11 and a fuel discharge port 112 for discharging the fuel that has finished the reaction at the anode electrode 3 are formed on the anode electrode 3 side of the case 11. Has been. A plurality of air supply ports 113 for supplying air into the case 11 are formed on the cathode 11 side of the case 11. The air supply port 113 is open to the atmosphere so that the air supply to the air chamber 41 is a natural intake. The air supply to the air supply port 113 may be configured to forcibly supply air to the air chamber 41 by an air pump or the like.

  A substantially rectangular anode electrode 3 and cathode electrode 4 are provided on both surfaces of the polymer solid electrolyte membrane 2 within a predetermined range with a predetermined width dimension from the outer edge. The polymer solid electrolyte membrane 2 is a polymer solid electrolyte resin as an electrolyte material composed of a proton conductive polymer, and is made of a stretched porous polytetrafluoroethylene (Poly Tetra Fluoro Ethylene, PTFE) film as a porous membrane. It is configured by impregnating the porous voids. As the polymer solid electrolyte resin, for example, a perfluorosulfonic acid polymer such as a Nafion membrane (trademark of DuPont), a fluorine polymer, a hydrocarbon polymer, an ionic liquid, a hydrogel, or the like can be employed. In some cases, a catalyst such as platinum, carbon powder, various ceramic powders and the like may be added to the solid polymer electrolyte resin as long as electronic conductivity does not occur.

Here, the stretched porous polytetrafluoroethylene (PTFE) film is obtained by stretching and porous PTFE mass as an electrolyte membrane material, and extending from these micronodules and the micronodules. It is a porous PTFE film having a structure composed of fine fibers that are three-dimensionally connected, and a large number of holes penetrating in the thickness direction are formed in this film. In the present embodiment, the stretched porous PTFE film has a thickness of 1 to 100 μm, preferably 3 to 30 μm, a pore diameter of 0.05 to 5 μm, preferably 0.5 to 2 μm, and a porosity of 60% to 98. %, Preferably 80 to 92%. If the film thickness is too thin, short circuits and gas leaks (cross leaks) are likely to occur, and if it is too thick, the electrical resistance increases. If the pore size is too small, impregnation of the polymer solid electrolyte resin becomes difficult, and if it is too large, the holding power of the polymer solid electrolyte resin becomes weak and the reinforcing effect becomes weak. If the porosity is too small, the resistance of the polymer solid electrolyte membrane is increased. If it is too large, the strength of PTFE itself is generally weakened and a reinforcing effect cannot be obtained.
As the porous membrane material, polyimide (PI), polyacrylonitrile (PAN), aramid, acrylic, polyester, polyethylene, polypropylene, polyacetal, etc. can be adopted in addition to expanded porous PTFE.

The anode electrode 3 and the cathode electrode 4 are composed of a carbon catalyst electrode film carrying a catalyst for decomposing methanol. Here, platinum etc. are employable as a catalyst, for example. On the anode electrode 3 side, in order to prevent poisoning of carbon monoxide CO, which is an intermediate product generated by the reaction between methanol and the catalyst, at least the catalyst on the anode electrode 3 side includes an alloy of platinum and ruthenium, etc. Is more preferable.
Here, the polymer solid electrolyte membrane 2, the anode electrode 3, and the cathode electrode 4 are integrally formed to form a membrane electrode assembly 20.
FIG. 2 shows a partially enlarged cross-sectional view of the fuel cell 1. As shown in FIG. 2, the anode electrode 3, the polymer solid electrolyte membrane 2, and the cathode electrode 4 of the membrane electrode assembly 20 are provided with uneven surfaces 3A, 2A, and 4A, respectively. The membrane electrode assembly 20 having these uneven surfaces 3A, 2A, 4A is manufactured by a manufacturing method described later.

The fuel diffusion layer 5 and the air diffusion layer 6 are porous membranes made of mesh metal foam (for example, steel wool) and diffuse the supplied fuel and oxygen to the anode electrode 3 and the cathode electrode 4, respectively. As shown in FIG. 2, the fuel diffusion layer 5 and the air diffusion layer 6 are provided on the surfaces facing the anode electrode 3 and the cathode electrode 4, respectively, on the uneven surfaces 5A and 6A having shapes corresponding to the shapes of the uneven surfaces 3A and 4A. Is formed. The fuel diffusion layer 5 and the air diffusion layer 6 may be made of aluminum, stainless steel or the like, respectively, a porous metal material such as sponge titanium, carbon paper supported on carbon, carbon cloth, or the like. It may be.
Further, lead wires (not shown) are connected to the current collectors 7 and 8, respectively, and are connected to an external load.

Next, a manufacturing method of the membrane electrode assembly 20 having the uneven surfaces 3A, 2A, 4A will be described.
The manufacturing method of the membrane electrode assembly 20 includes an uneven surface forming step for forming the uneven surface 5A of the fuel diffusion layer 5 and the uneven surface 3A of the anode electrode 3, and a polymer solid electrolyte membrane with respect to the uneven surface 3A of the anode electrode 3. And a film pressing step for pressing 2.
In the uneven surface forming step, the surface of the fuel diffusion layer 5 facing the anode electrode 3 is subjected to mechanical processing such as press molding or cutting to form the uneven surface 5A. Then, the anode electrode 3 having a predetermined thickness is formed on the uneven surface 5A by a spray coating method, a dip coating method, or the like. At this time, since the anode electrode 3 is formed following the shape of the uneven surface 5A, an uneven surface 3A having substantially the same shape as the uneven surface 5A is formed on the surface of the anode electrode 3.

FIG. 3 is a diagram showing a film pressing process.
In the membrane pressing step, as shown in FIG. 3A, the polymer solid electrolyte membrane 2 is pressed against the anode electrode 3 on which the uneven surface 3A is formed. When pressing, a press die 90 having an uneven surface 90A having a shape corresponding to the shape of the uneven surface 3A is used. The press die 90 is disposed on the side opposite to the side on which the uneven surface 3A is disposed with respect to the polymer solid electrolyte membrane 2, and the polymer solid electrolyte membrane 2 is uneven as shown in FIG. 3 (B). Press against the surface 3A with a predetermined pressure.
The polymer solid electrolyte membrane 2 is pressed by the press die 90 and deforms and extends along the concavo-convex surface 3A while the fine fibers in the porous PTFE film are partially broken, and is uneven on the surface in conformity with the concavo-convex surface 3A. Surface 2A is formed. In this case, it is desirable that the film pressing process is performed by being divided into a plurality of times. By dividing and pressing a plurality of times, the generation of pinholes due to the breakage of the polymer solid electrolyte membrane 2 can be reliably prevented, and the polymer solid electrolyte membrane 2 can be satisfactorily adapted to the uneven surface 3A.

In this membrane pressing step, an exciting step of applying vibration at a predetermined frequency to the solid polymer electrolyte membrane 2 is performed simultaneously with the membrane pressing step. In the vibration process, while pressing the solid polymer electrolyte membrane 2 with the press die 90, the press die 90 is vibrated at a predetermined frequency and a predetermined amplitude, and the solid polymer electrolyte membrane 2 is vibrated. In the polymer solid electrolyte membrane 2, the internal fine fibers are deformed and broken by this vibration, and the entire polymer solid electrolyte membrane 2 is deformed and conforms to the uneven surface 3 A of the anode electrode 3, and the fiber density of the fine fibers is high. Become.
Moreover, in this membrane press process, the heating process which heats the polymer solid electrolyte membrane 2 as needed is performed simultaneously with the said membrane press process. In the heating step, the press die 90 is heated to a predetermined temperature while the polymer solid electrolyte membrane 2 is pressed by the press die 90. Alternatively, the solid polymer electrolyte membrane 2 may be heated by housing the fuel diffusion layer 5, the anode electrode 3, the solid polymer electrolyte membrane 2, and the press die 90 in a suitable heating tank. By this heating, the fine fibers of the polymer solid electrolyte membrane 2 are softened, and the polymer solid electrolyte membrane 2 is adapted to the uneven surface 3A. Further, in this heating step, the fine fibers of the polymer solid electrolyte membrane 2 are dissolved by adjusting the predetermined temperature appropriately within a range not destroying the polymer solid electrolyte resin in the polymer solid electrolyte membrane 2. These fine fibers may be melt-bonded. In this case, the fine fibers are also melt-bonded to the uneven surface 3A.

  After the membrane pressing step, the cathode electrode 4 is formed on the concavo-convex surface 2A of the polymer solid electrolyte membrane 2 by a spray coating method, a dip coating method, or the like, and the membrane electrode assembly 20 is manufactured. Then, the air diffusion layer 6 on which the uneven surface 6A having a shape corresponding to the uneven surface 5A of the fuel diffusion layer 5 is formed in advance by pressing or cutting is joined to the cathode electrode 4 to obtain the fuel cell 10. The cathode electrode 4 may be formed on the uneven surface 6 </ b> A of the air diffusion layer 6 in advance and then joined to the solid polymer electrolyte membrane 2 together with the air diffusion layer 6.

According to such a first embodiment, the following effects can be obtained.
(1) In the membrane pressing step, the polymer solid electrolyte membrane 2 is pressed against the irregular surface 3A of the anode electrode 3 by the press die 90 to form the irregularities of the membrane electrode assembly 20, so that the polymer solid electrolyte membrane 2 Can satisfactorily follow the uneven surface 3A of the anode electrode 3, and the uneven surface 2A along the shape of the uneven surface 3A can be formed. Therefore, the contact between the anode electrode 3 and the polymer solid electrolyte membrane 2 can be improved. Moreover, since the uneven surface 2A corresponding to the shape of the uneven surface 3A can be formed, the cathode electrode 4 having the uneven surface 4A having a shape corresponding to the shape of the uneven surface 3A can be satisfactorily contacted. Thereby, the proton conductivity of the polymer solid electrolyte membrane 2 can be improved, and the reaction efficiency of the fuel cell 1 can be improved.
Further, since the unevenness is formed in the membrane electrode assembly 20, the contact area between the anode electrode 3 and the cathode electrode 4, fuel and air can be improved with respect to a certain volume. Therefore, the amount of current (output) per fixed volume of the fuel cell 1 can be improved. On the contrary, since the volume necessary for obtaining a constant amount of current (output) can be reduced, downsizing of the fuel cell 1 can be promoted.

(2) Since the vibration step is performed in the membrane pressing step, a part of the fine fibers of the polymer solid electrolyte membrane 2 can be broken so that the polymer solid electrolyte membrane 2 can follow the uneven surface 3A more. Therefore, the contact between the solid polymer electrolyte membrane 2 and the anode electrode 3 and the cathode electrode 4 can be made more reliable and better.
(3) Since the heating step is performed as necessary in the membrane pressing step, the fine fibers of the polymer solid electrolyte membrane 2 can be softened by heat. Therefore, the polymer solid electrolyte membrane 2 can be more easily deformed, and is better adapted to the shape of the uneven surface 3 </ b> A of the anode electrode 3, so that the contact with the anode electrode 3 can be made more reliably and better.

 (4) In the membrane pressing step, the polymer solid electrolyte membrane 2 is formed by impregnating the porous solid portion of the stretched porous PTFE film with the polymer solid electrolyte resin in advance. The polymer solid electrolyte membrane 2 can be formed on the concavo-convex surface 3A simply by pressing the surface 3A. Therefore, operations such as impregnation with a polymer solid electrolyte resin after the membrane pressing step can be omitted, and the manufacturing operation of the fuel cell 1 can be simplified.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the second embodiment, the stretched porous PTFE film of the polymer solid electrolyte membrane 2 of the first embodiment is subjected to a membrane pressing step without impregnating the polymer solid electrolyte resin, and then impregnated with the polymer solid electrolyte resin. The point which performs an electrolyte impregnation process differs from 1st embodiment.
In the membrane pressing step, the stretched porous PTFE film not impregnated with the polymer solid electrolyte resin is pressed against the uneven surface 3A of the anode electrode 3 by the press die 90 in the same manner as the membrane pressing step of the first embodiment. Unevenness is formed on the stretched porous PTFE film.
Next, in the electrolyte impregnation step, the polymer solid electrolyte resin dissolved in the solvent is sprayed, for example, so that the porous void portion of the stretched porous PTFE film is impregnated with the polymer solid electrolyte resin. 2 is formed. Here, as the solvent for dissolving the polymer solid electrolyte resin, for example, when the polymer solid electrolyte resin is a perfluorosulfonic acid polymer, alcohols such as isopropyl alcohol (IPA) can be employed. When the solid electrolyte resin is an ionic liquid, hydrogel, or the like, water or the like can be employed.
In this embodiment, since the polymer solid electrolyte resin is not impregnated in the membrane pressing step, the predetermined temperature can be set to a relatively high temperature when the heating step is performed.

According to the second embodiment, in addition to the same effects as the effects (1), (2), and (3) of the first embodiment, the following effects can be obtained.
(5) Since the electrolyte impregnation step is performed after the membrane pressing step, the heating step can be performed at a relatively high temperature, and a part of the fine fibers of the polymer solid electrolyte membrane 2 is dissolved. Since the fine fibers can be melted and bonded to each other, the shape of the polymer solid electrolyte membrane 2 can be reliably maintained, and the configuration of the polymer solid electrolyte membrane 2 can be strengthened. Further, since a part of the fine fibers can be dissolved and adhered to the anode electrode 3, the contact between the polymer solid electrolyte membrane 2 and the anode electrode 3 can be further improved.
(6) Since the vibrating step is performed on the stretched porous PTFE film in the membrane pressing step, a part of the fine fibers of the polymer solid electrolyte membrane 2 can be broken and shortened, so that the absorbency of the stretched porous PTFE film Can be improved. Therefore, in the electrolyte impregnation step, the stretched porous PTFE film can be satisfactorily impregnated with the polymer solid electrolyte resin, and good proton conductivity can be exhibited.

[Third embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment in that it includes a shrinking step for shrinking the polymer solid electrolyte membrane 2 before the membrane pressing step of the first embodiment.
FIG. 4 shows a manufacturing process of the membrane electrode assembly 20 according to the third embodiment. In FIG. 4, the polymer solid electrolyte membrane 2 is subjected to a shrinking step before the membrane pressing step.
In the shrinking step, as shown in FIG. 4A, the polymer solid electrolyte membrane 2 is shrunk to form a shrinking fiber. In order to form in a contracted fiber shape, for example, a method in which the polymer solid electrolyte membrane 2 is shrunk by a thin fiber and then directly bonded can be employed.
Thereafter, in the membrane pressing step, when the contracted polymer solid electrolyte membrane 2 is pressed against the concavo-convex surface 3A by the press die 90, the contracted fibers return to the original height as shown in FIG. The molecular solid electrolyte membrane 2 as a whole expands and conforms to the shape of the uneven surface 3A of the anode electrode 3, thereby forming the uneven surface 2A on the surface of the polymer solid electrolyte membrane 2.
In this membrane pressing step, an elongated porous PTFE film that is not impregnated with the polymer solid electrolyte resin may be pressed against the uneven surface 3A as in the second embodiment. In that case, an electrolyte impregnation step of impregnating the polymer solid electrolyte resin may be performed after the membrane pressing step.

According to the third embodiment, the same effects as the effects (1), (2), (3), and (4) of the first embodiment can be obtained, and as in the second embodiment. When performing the electrolyte impregnation step after the membrane pressing step, the same effects as the effects of (5) and (6) of the second embodiment can be obtained instead of the effect of (4) of the first embodiment, According to the third embodiment, the following effects can be obtained.
(7) Since the shrinking step is performed before the membrane pressing step, the polymer solid electrolyte membrane 2 can be stretched in the membrane pressing step without breaking the internal fine fibers. Therefore, the breakage of the solid polymer electrolyte membrane 2 can be reliably and satisfactorily prevented, and the occurrence of pressing failure in the membrane pressing step can be reduced, so that the yield can be improved.
In addition, since the contraction step is performed before the membrane pressing step, the extension width of the solid polymer electrolyte membrane 2 can be increased, so that the larger uneven surface 3A can be satisfactorily followed. Therefore, the aspect ratio can be increased in the membrane pressing step, and the surface area of the membrane electrode assembly 20 can be formed larger.

[ Reference form 1 ]
Next, Reference Embodiment 1 will be described. Reference form 1 is different from the first embodiment in that a porous film is directly formed on the uneven surface of the anode electrode.
FIG. 5 shows a manufacturing process of the membrane electrode assembly according to the first embodiment . 5, the manufacturing method of the membrane electrode assembly 20 (see FIG. 1) is a porous membrane in which a fibrous electrolyte membrane material is laminated on the uneven surface 3A of the anode electrode 3 to form a porous membrane 21. A forming step and an electrolyte impregnation step of impregnating the porous membrane 21 with an electrolyte material.

The porous membrane forming step includes a spraying step by a so-called melt blow method in which the electrolyte membrane material is dissolved and sprayed onto the uneven surface 3A. In the spraying process, as shown in FIG. 5A, the electrolyte membrane material is sprayed onto the uneven surface 3A using the spray nozzle 91.
FIG. 6 shows a plan view of the spray nozzle 91. As shown in FIG. 6, a large number of minute pores 91 </ b> A are formed at the tip of the spray nozzle 91. The dimensions of these pores 91 </ b> A are set corresponding to the dimensions of the fine fibers forming the porous membrane 21. The spray nozzle 91 is connected to an electrolyte membrane material supply means (not shown) that stores the electrolyte membrane material and supplies it to the spray nozzle 91. The electrolyte membrane material supply means is connected to an appropriate heating device or the like. It is set to a predetermined temperature and supplied to the spray nozzle 91 in a state where the electrolyte membrane material is dissolved.

In the spraying step, as shown in FIG. 5A, the end surface of the spray nozzle 91 is opposed to the uneven surface 3A of the anode electrode 3, and the electrolyte membrane material dissolved from the pores 91A is sprayed onto the uneven surface 3A. . The electrolyte membrane material is sprayed in a fiber shape with a size corresponding to the size of the pores 91A, and is laminated on the uneven surface 3A. By moving the spray nozzle 91 on the concavo-convex surface 3A, as shown in FIG. 5B, a porous film 21 is formed by laminating an electrolyte film material having a predetermined thickness in a predetermined range on the concavo-convex surface 3A. To do.
After the spraying step, in the electrolyte impregnation step, the polymer membrane electrolyte membrane 2 is formed by impregnating the porous membrane 21 formed on the uneven surface 3A with the electrolyte material, as in the second embodiment. Thereafter, the cathode electrode 4 (see FIG. 1) is laminated on the surface of the solid polymer electrolyte membrane 2 to obtain a membrane electrode assembly.

Here, in the porous film forming step, a mixing step of mixing an adhesive with the electrolyte membrane material may be provided before the spraying step. In the mixing step, a predetermined amount of an appropriate adhesive is mixed with the electrolyte membrane material previously dissolved in the electrolyte membrane material supply means. Alternatively, a mixing means may be provided near the tip of the spray nozzle 91 to mix the adhesive with the electrolyte membrane material.
When the spraying step is performed after the mixing step, the electrolyte membrane material mixed with the adhesive is laminated in a fibrous form on the uneven surface 3A to form the porous membrane 21. The porous membrane 21 is adhered to the concavo-convex surface 3 </ b> A while the fine fibers are adhered to each other by an adhesive to maintain the shape.

Alternatively, instead of providing a mixing step, an adhesive spraying step of spraying an adhesive onto the porous membrane 21 may be performed after the porous membrane forming step. In the adhesive spraying process, a predetermined amount of liquid adhesive is sprayed onto the porous film 21 formed in the spraying process using another spray nozzle or the like. The adhesive impregnates the porous film 21 to bond the fine fibers to each other, and a part of the adhesive reaches the uneven surface 3A to bond the porous film 21 and the anode electrode 3 together.
The adhesive spraying step may be performed after the porous membrane 21 is formed and before the electrolyte impregnation step, or may be performed after the polymer solid electrolyte membrane 2 is formed in the electrolyte impregnation step.

According to the first embodiment , the following effects can be obtained.
(8) Since the melted electrolyte membrane material is sprayed in a fiber shape and laminated on the uneven surface 3A by the porous film forming step including the spraying step, the porous film 21 along the shape of the uneven surface 3A is formed. It can be formed by simple work. Therefore, the contact between the anode electrode 3 and the electrolyte membrane 2 can be improved.
In addition, there is no need to previously form the electrolyte membrane material in a fibrous form, and a necessary amount of the electrolyte membrane material is formed in a fibrous form by dissolving and spraying the electrolyte membrane material, so there is no waste of material. The manufacturing process can be simplified.
Further, since the unevenness is formed in the membrane electrode assembly 20, the contact area of the anode electrode 3 and the cathode electrode 4 with the fuel and air with respect to a certain volume, as in the effect (1) of the first embodiment. Can be improved. Therefore, the amount of current (output) per fixed volume of the fuel cell 1 can be improved. On the contrary, since the volume necessary for obtaining a constant amount of current (output) can be reduced, downsizing of the fuel cell 1 can be promoted.

(9) When the mixing step is provided, since the electrolyte membrane material mixed with the adhesive in the spraying step is sprayed, the electrolyte membrane material can be adhered to the uneven surface 3A well and reliably simultaneously with the spraying. The shape of the porous membrane 21 can be reliably maintained.
(10) When the adhesive spraying step is provided, the adhesive is sprayed on the porous membrane 21 formed in the spraying step, so that the shape of the porous membrane 21 can be reliably held on the uneven surface 3A. Further, since it is not necessary to mix an adhesive with the electrolyte membrane material, waste of the material can be prevented.

[ Reference form 2 ]
Next, Reference Embodiment 2 will be described. Reference Embodiment 2, in the spraying process of the reference embodiment 1, instead of spraying the electrolyte membrane material dissolved in that an electrolyte membrane material for the fibrous spraying a solution dispersed in a solvent is, the reference embodiment 1 Different.
In Reference Form 2 , the porous membrane forming step includes spraying a solution in which a fibrous electrolyte membrane material is dispersed in a solvent, a spraying step by a so-called wet nonwoven fabric method, and pressing the porous membrane against the anode electrode. And a pressing step for evaporating, and an evaporation step for evaporating the solvent in the solution.

FIG. 7 shows a manufacturing process of the membrane electrode assembly according to Reference Embodiment 2 . In the spraying step, as shown in FIG. 7A, a predetermined amount of a liquid in which the electrolyte membrane material is dispersed on the uneven surface 3A is sprayed by the spray nozzle 91. The electrolyte membrane material supply means (not shown) accommodates a solution in which the electrolyte membrane material previously formed in a fiber shape is dispersed in a solvent. Here, as the solvent, for example, alcohols such as isopropyl alcohol, water, and the like can be employed. The sprayed liquid is laminated | stacked on the uneven | corrugated surface 3A in the shape of a nonwoven fabric, as shown in FIG.
Next, in the pressing step, as shown in FIG. 7B, the nonwoven fabric layer 22 is pressed against the uneven surface 3 </ b> A by a press die 90, and the fibrous electrolyte membrane dispersed in the nonwoven fabric layer 22 is used. The material is condensed to form a porous film 21 having a predetermined thickness as shown in FIG.
In the evaporation step, the solvent in the porous film 21 is evaporated by leaving or heating the porous film 21 for a predetermined time. This evaporation step may be performed simultaneously with the pressing step, that is, while pressing the nonwoven fabric layer 22 with the press die 90.
Thereafter, in the electrolyte impregnation step, the porous membrane 21 is impregnated with an electrolyte to form a polymer solid electrolyte membrane.

In addition, you may provide the mixing process which mixes an adhesive agent with a solution similarly to the reference form 1 before a spraying process. Or after forming the porous membrane 21, that is, after the evaporation step, an adhesive spraying step for spraying the adhesive onto the porous membrane 21 may be provided.
Furthermore, as in the first embodiment, a vibration process for applying vibration to the porous film 21 simultaneously with the pressing process, or a heating process for applying heat to the porous film 21 simultaneously with the pressing process may be performed.

According to this reference embodiment 2, effect similar to the effect of (1) in the first embodiment, and the reference embodiment 1 (9), and effects similar effect is obtained in (10), vibration When the step or the heating step is performed, the same effects as the effects (2) and (3) of the first embodiment and the same effects as the effects (5) and (6) of the second embodiment are obtained. In addition to the above, according to Reference Mode 2 , the following effects can be obtained.
(11) Since the solvent is evaporated in the evaporation step after spraying the solution in which the fibrous electrolyte membrane material is dispersed in the solvent in the spraying step, unlike the first embodiment , the electrolyte membrane material is heated. Therefore, the handling property of the electrolyte membrane material can be improved.
Moreover, the uneven polymer solid electrolyte membrane 2 having favorable irregularities can be formed at a desired fiber density and a desired thickness by a pressing process.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
The electrode forming the electrolyte membrane is not limited to being formed on the anode electrode, but may be formed on the cathode electrode. In this case, an uneven surface is formed on the air diffusion layer, a cathode electrode is formed on the uneven surface, and an electrolyte membrane is formed on the uneven surface of the cathode electrode by the above-described manufacturing method.
The shape of the concavo-convex surface of the membrane electrode assembly is not limited to a continuous arc-shaped concavo-convex shape, and may be an concavo-convex shape having a substantially rectangular cross section when a groove is formed by cutting, for example. In addition, the shape of the uneven surface is not limited to the one in which the same cross-sectional shape is continuous, and a plurality of different cross-sectional shapes may be formed, or the unevenness is formed unevenly (discontinuously). It may be a thing. In short, the shape of the concavo-convex surface can be arbitrarily set as long as the surface area of the membrane electrode assembly can be increased.
As a material for the porous film, for example, porous ceramics, glass, apatite, porous silicon, zeolite and the like can be used in addition to those described in the above-described embodiment.

In Reference Form 2 , the spraying step of spraying a solution in which a fibrous electrolyte membrane material is dispersed in a solvent was performed. However, the present invention is not limited to this. For example, on the electrode on which an uneven surface is formed, The electrolyte membrane may be formed by forming a mold and filling the solution into the mold and then evaporating the solvent.
The membrane electrode assembly is applied to a fuel cell, but is not limited thereto, and can be applied to, for example, a lithium battery using a lithium ion conductive solid electrolyte, a water electrolysis apparatus using a proton conductive solid electrolyte, and the like.
The fuel cell including the membrane electrode assembly obtained by the implementation of the present invention can improve the output with respect to a certain volume, and on the contrary, can promote downsizing with respect to the required output, such as a mobile phone or a notebook computer. It can be applied to portable devices, cars, and other arbitrary devices.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limited to the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

Sectional drawing which shows the fuel cell concerning 1st embodiment of this invention. 1 is a partially enlarged cross-sectional view of a fuel cell according to a first embodiment. The figure which shows the manufacturing process of the membrane electrode assembly concerning 1st embodiment. The figure which shows the manufacturing process of the membrane electrode assembly concerning 3rd embodiment of this invention. The figure which shows the manufacturing process of the membrane electrode assembly concerning the reference form 1. FIG. The top view of the spray nozzle concerning the reference form 1. FIG. The figure which shows the manufacturing process of the membrane electrode assembly concerning the reference form 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Polymer solid electrolyte membrane (electrolyte membrane), 2A, 3A, 4A ... Uneven surface, 3 ... Anode electrode (electrode), 4 ... Cathode electrode (electrode), 5 ... Fuel diffusion layer, 6 ... Air diffusion layer, 10 ... fuel cell, 20 ... membrane electrode assembly, 90 ... press die, 91 ... spray nozzle.

Claims (4)

A method for producing a membrane electrode assembly comprising an electrolyte membrane and an electrode formed on the surface of the electrolyte membrane,
A membrane that presses the electrolyte membrane in which a porous membrane is impregnated with an electrolyte material having proton conductivity with a press die having a shape corresponding to the shape of the irregular surface, with respect to the irregular surface formed on the surface of the electrode. A method for producing a membrane electrode assembly, comprising a pressing step. A method for producing a membrane electrode assembly comprising an electrolyte membrane and an electrode formed on the surface of the electrolyte membrane,
A film pressing step for pressing the porous film with a press die having a shape corresponding to the shape of the uneven surface, with respect to the uneven surface formed on the surface of the electrode,
An electrolyte impregnation step of impregnating the porous membrane with an electrolyte material having proton conductivity to form the electrolyte membrane. A method for producing a membrane electrode assembly, comprising: In the manufacturing method of the membrane electrode assembly according to claim 1 or 2,
The manufacturing method of the membrane electrode assembly characterized by having the vibration process which applies a vibration to the said porous membrane or the said electrolyte membrane simultaneously with the said membrane press process. In the manufacturing method of the membrane electrode assembly according to any one of claims 1 to 3,
A method for producing a membrane / electrode assembly, comprising a shrinking step of shrinking the porous membrane or the electrolyte membrane before the membrane pressing step.

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