JP2007214101A - Electrolyte membrane-electrode assembly and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte membrane-electrode assembly in which corrosion of a cathode catalyst at starting and stopping and decomposition of an electrolyte membrane during holding an OCV can be suppressed effectively. <P>SOLUTION: This is the electrolyte membrane-electrode assembly which is provided with a polyelectrolyte membrane, a cathode catalyst layer arranged on one side of the polyelectrolyte membrane, an anode catalyst layer arranged on the other side of the polyelectrolyte membrane, and a first gasket layer formed at least at one part of the end part of the cathode catalyst layer so that the area of the effective anode catalyst layer will become larger than that of the effective cathode catalyst layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolyte membrane-electrode assembly (MEA), particularly to an electrolyte membrane-electrode assembly for a fuel cell and a method for producing the same. In particular, the present invention relates to an electrolyte membrane-electrode assembly (MEA) in which cathode catalyst corrosion during start / stop / continuous operation and decomposition of the electrolyte membrane during OCV (Open Circuit Voltage) holding assuming idle stop operation are suppressed. And a manufacturing method thereof.

  In recent years, in response to social demands and trends against the background of energy and environmental problems, fuel cells that can operate at room temperature and obtain high output density have attracted attention as power sources for electric vehicles and stationary power sources. A fuel cell is a clean power generation system in which the product of an electrode reaction is water in principle and has almost no adverse effect on the global environment. In particular, the polymer electrolyte fuel cell is expected as a power source for electric vehicles because it operates at a relatively low temperature. In general, the polymer electrolyte fuel cell has a structure in which an electrolyte membrane-electrode assembly is sandwiched between a gas diffusion layer and a separator. The electrolyte membrane-electrode assembly is obtained by sandwiching a polymer electrolyte membrane between a pair of electrode catalyst layers.

In the polymer electrolyte fuel cell having the MEA as described above, the following electrochemical reaction proceeds. First, hydrogen contained in the fuel gas supplied to the anode side is oxidized by the catalyst component to become protons and electrons (2H ₂ → 4H ⁺ + 4e ⁻ ). Next, the generated protons pass through the solid polymer electrolyte contained in the electrode catalyst layer and the polymer electrolyte membrane in contact with the electrode catalyst layer, and reach the cathode side electrode catalyst layer. In addition, the electrons generated in the anode-side electrode catalyst layer include a conductive carrier constituting the electrode catalyst layer, a gas diffusion layer in contact with a side of the electrode catalyst layer different from the polymer electrolyte membrane, a separator, and an external circuit. To reach the cathode side electrocatalyst layer. The protons and electrons that have reached the cathode-side electrode catalyst layer react with oxygen contained in the oxidant gas supplied to the cathode side to generate water (O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O). In the fuel cell, electricity can be taken out through the above-described electrochemical reaction.

  In such an MEA, there has been a problem that the membrane is damaged due to a considerable mechanical stress applied to the conventional membrane, and the battery life is not sufficient. In order to solve this problem, it is considered to reinforce the membrane by sealing the edge region of the MEA (Patent Documents 1 to 4). Among these, Patent Document 1 discloses the arrangement of the electrode peripheral portion and the electrode of the solid polymer electrolyte membrane for the purpose of increasing the mechanical strength of the outer edge of the solid polymer electrolyte membrane and preventing damage to the solid polymer electrolyte membrane. It is described that an outer edge portion of a solid polymer electrolyte membrane not covered is covered with a reinforcing membrane, and a gas seal portion is arranged on the outer edge portion of the solid polymer electrolyte membrane. Patent Document 2 discloses a frame-shaped protective film, a gas sealing material and an electrode for the purpose of preventing damage to the solid polymer electrolyte film due to differential pressure of reaction gas applied to the solid polymer electrolyte film or mechanical stress. It describes that it forms in the peripheral part of a solid polymer electrolyte membrane so that both peripheral parts may be coat | covered. In Patent Document 3, the area of the fuel electrode and the oxidant electrode in contact with the film is changed depending on the arrangement of the frame-shaped reinforcing sheet (Claims 4 to 6), thereby preventing the polymerization of each catalyst layer across the film. And preventing damage to the membrane. According to this method, it is described that the membrane life can be improved by preventing the membrane from being damaged by the mechanical stress applied to the membrane and discharging the generated water satisfactorily. Further, in Patent Document 4, a seal is interposed between the outer peripheral edge of the catalyst layer and the separator, the area of the catalyst layer being changed, for the purpose of preventing the porous carbon member constituting the electrode from sagging. In addition, it is described that the outer peripheral edge portion of the catalyst layer is subjected to a compression process in advance corresponding to the contact surface of the seal.

In addition, in a fuel cell using an acid as an electrolyte, particularly a phosphoric acid type fuel cell, in order to suppress deterioration of the catalyst layer, a layer made of a water-resistant material is arranged in the edge region of the cathode catalyst layer, or an anode catalyst layer It is described that the corrosion area of carbon in the cathode catalyst layer is suppressed by making the coating area of the coating layer larger than the coating area of the cathode catalyst layer (Patent Document 5). Specifically, in this publication, 0.2 g / cc of a fluororesin powder such as fluoroethylenepropylene (FEP) is supported on an electrolyte matrix per unit volume, and is in contact with the edge region on the cathode catalyst layer side. (See paragraph “0024” and FIG. 1).
JP-A-5-2442897 Japanese Patent Laid-Open No. 5-21077 Japanese Patent Laid-Open No. 10-172587 JP 2004-39385 A Japanese Patent Laid-Open No. 5-21077

Conventionally, the polymer electrolyte fuel cell as described above has various problems. As a typical and important problem, there is a problem of deterioration of the electrolyte membrane in an idle stop (OCV: Open Circuit Voltage) state. This deterioration mechanism will be described with reference to FIG. In other words, since the electrolyte membrane does not completely block the gas (impermeability state), depending on the concentration gradient (partial pressure) of oxygen or hydrogen gas, hydrogen flows from the anode side to the cathode side, and from the cathode side to the anode side. Oxygen and nitrogen are slightly permeated (dissolved and diffused) toward the side (this phenomenon is also referred to as “cross leak”). In particular, at the time of OCV, the oxygen concentration at the interface between the cathode and the electrolyte membrane is higher than that at the time of power generation. Therefore, the amount of oxygen that dissolves and diffuses from the cathode side to the anode side through the electrolyte membrane is also larger than at the time of power generation. For this reason, oxygen moves from the cathode side to the anode side due to cross leak, and oxygen reacts directly with hydrogen on the anode side, causing a reaction of H ₂ + O ₂ → H ₂ O ₂ , resulting in hydrogen peroxide (H ₂ O ₂ ) is generated, hydrogen is transferred from the anode side to the cathode side, and hydrogen directly reacts with oxygen on the cathode side to similarly generate hydrogen peroxide. It is known that this hydrogen peroxide decomposes the electrolyte component (ionomer) contained in the electrolyte membrane or the anode or cathode to chemically deteriorate the electrolyte membrane. Here, considering the relationship between the potential of the anode catalyst layer and the cathode catalyst layer and the decomposition reaction of hydrogen peroxide, the potential is relatively high (about 0.6 to 1 V) with respect to the electrolyte potential. The hydrogen peroxide that cross-leaked from the anode catalyst layer directly reacts with the oxygen of the anode, so that the hydrogen peroxide that is produced becomes oxygen and proton relatively quickly by the reaction of H ₂ O ₂ → O ₂ + 2H ⁺ + 2e ^−. Decompose. On the other hand, since the potential is low on the anode side, the above-described decomposition reaction of hydrogen peroxide hardly occurs. For this reason, hydrogen peroxide generated frequently on the anode side moves into the electrolyte membrane due to concentration diffusion, oxidatively degrades the electrolyte membrane, or the presence of cations (eg, Fe ²⁺ , Cu ²⁺ ) in the electrolyte membrane. As a result, the electrolyte membrane components are deteriorated at an accelerated rate. In particular, when the anode catalyst layer and the cathode catalyst layer are not completely aligned and misaligned, supply to the cathode catalyst layer in the area where the cathode catalyst layer does not exist and only the anode catalyst layer exists. Since the oxygen directly moves to the anode catalyst layer side, there is a large amount of oxygen cross-leakage, and hydrogen peroxide in such a region is relatively large. Therefore, there is an anode catalyst layer in the surrounding area. Compared to the region (center portion), the electrolyte membrane is further deteriorated.

  The above problem has been raised relatively recently. Currently, although a solution is strongly desired, no effective solution has been found. In fact, the above Patent Documents 1 to 4 do not disclose or suggest these problems at all. In fact, Patent Documents 1 and 2 aim to improve the mechanical strength of the outer edge of the solid polymer electrolyte membrane. In the structures described in Patent Documents 1 and 2, the decomposition of the electrolyte membrane as described above can be performed. Since the suppression is not taken into consideration, when the catalyst layer is misaligned with respect to the thickness direction of the MEA, it is described in Patent Document 5 as well as the deterioration of the electrolyte membrane due to the oxygen cross leak described above. The problem that the corrosion of the catalyst also occurs and the durability of the MEA deteriorates cannot be solved. Although Patent Document 3 describes that the area of the catalyst layer is changed between the fuel electrode (anode) and the oxidant electrode (cathode), paragraph [0036] and FIGS. As seen, the area of the catalyst layer is the fuel electrode (anode) <the oxidant electrode (cathode). In the MEA having such a catalyst layer, the problem of the corrosion of the carbon support in the cathode catalyst layer described above and the idle The problem of deterioration of the electrolyte membrane in the stopped state cannot be solved. Further, although Patent Document 4 describes that the area of the anode catalyst layer is larger than the area of the cathode catalyst layer (paragraph [0018]), this configuration is an improvement in sealing performance between the MEA and the separator. Furthermore, there is no description about the area ratio between the area of the anode catalyst layer and the area of the cathode catalyst layer.

  Further, although Patent Document 5 certainly describes the corrosion of the carbon support in the catalyst layer, it is particularly intended for fuel cells that use an acid such as phosphoric acid as an electrolyte among fuel cells. No consideration is given to electrolyte degradation. For this reason, a layer is formed by supporting the fluorine-based resin powder as it is, but since this layer is gas permeable and does not function as a gasket, it is used as an electrolyte membrane-electrode of a polymer electrolyte fuel cell. Even when applied to a joined body, during OCV, oxygen leaked from the vicinity of the cathode diffuses to the anode side and directly reacts with hydrogen in the vicinity of the anode to generate a large amount of hydrogen peroxide, which oxidizes the electrolyte membrane. It will induce degradation. That is, the presence of the carrier layer cannot sufficiently suppress oxygen cross-leakage from the cathode side, so that oxidative deterioration of the electrolyte membrane due to the formation of hydrogen peroxide cannot be sufficiently suppressed or prevented.

  Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrolyte membrane-electrode assembly that can effectively suppress decomposition of the electrolyte membrane during OCV holding.

  Another object of the present invention is to produce an electrolyte membrane-electrode assembly in which a cathode catalyst layer and an anode catalyst layer having a desired size can be easily and accurately arranged at desired positions of the polymer electrolyte membrane, respectively. Is to provide a way.

As a result of intensive studies to achieve the above object, the present inventors have found that an anode catalyst is formed by forming a gasket layer at the end of the cathode catalyst layer, preferably at the ends of the cathode catalyst layer and the anode catalyst layer. It has been found that the size of each layer and the cathode catalyst layer can be easily controlled, and that the alignment of each catalyst layer is easy. Further, the end of the catalyst layer is effectively sealed as a catalyst by sealing the end of the catalyst layer with a gas-impermeable gasket layer so that the size of the anode catalyst layer is larger than that of the cathode catalyst layer. The area of the cathode catalyst layer (effective cathode catalyst layer) in which the reaction of O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O occurs during power generation effectively works as a catalyst, that is, 2H ₂ → 4H ⁺ + 4e ⁻ during operation (power generation) The cathode catalyst layer is defined to be smaller than the area of the anode catalyst layer where the reaction occurs (effective anode catalyst layer), and further, the cathode catalyst layer is particularly prone to oxygen cross-leakage from the cathode catalyst layer side to the anode catalyst layer side, which causes oxidative degradation of the electrolyte membrane. By covering the end region with a gas-impermeable gasket layer, the region where the cross leak occurs can be minimized, It has also been found that the amount of oxygen cross-leakage can be suppressed to a minimum, so that oxidative deterioration of the electrolyte membrane can be effectively suppressed. More specifically, as shown in FIG. 3A, an MEA (the upper stage in FIG. 3A) having an effective cathode catalyst layer size of 25 cm ² and an effective anode catalyst layer size of 26 cm ² , and an effective cathode catalyst layer In both cases, the MEA having a size of 26 cm ² and an effective anode catalyst layer size of 25 cm ² (lower part of FIG. 3A) has an effective catalyst layer area when incorporated in the fuel cell stack, that is, the smaller area, ie, In the above case, it is 25 cm ² . On the other hand, oxygen cross-leakage depends on the area of the effective cathode catalyst layer to which oxygen is supplied because oxygen cross-leaks from the cathode catalyst layer side to the anode catalyst layer side. That is, as shown in FIG. 3B, in the MEA in which the size of the effective cathode catalyst layer is 25 cm ² and the size of the effective anode catalyst layer is 26 cm ² (the upper stage in FIG. 3B), the oxygen crossover region is 25 cm ² . However, in the MEA in which the size of the effective cathode catalyst layer is 26 cm ² and the size of the effective anode catalyst layer is 25 cm ² (the lower stage in FIG. 3B), the oxygen crossover region is 26 cm ² . For this reason, the MEA in the upper part of FIGS. 3A and 3B where the effective catalyst layer area and the area of the oxygen crossover region are the same, the MEA in the upper part of FIGS. 3A and 3B has a smaller effective catalyst layer area than the area of the oxygen crossover region. Compared with MEA, oxygen cross-leak from the cathode catalyst layer side to the anode catalyst layer side, and hence oxidative degradation of the electrolyte membrane, can be significantly suppressed.

  Further, the present inventors adopt the above-described configuration to seal the periphery where only the anode catalyst layer is present without the cathode catalyst layer with a gas-impermeable gasket layer, and particularly at the end of the cathode catalyst layer. It is possible to suppress the oxygen cross-leak from the cathode to the anode, which was prominent in the process, and to significantly suppress the production of hydrogen peroxide on the anode side in this region, thereby effectively degrading the electrolyte membrane. It has also been found that it can be prevented / suppressed.

  In addition to the above findings, the present inventors have used a gasket layer for sealing and gasketing by using an adhesive (especially a hot-melt adhesive) when forming a gasket layer at the end or periphery of the catalyst layer. It has been found that the layer formation can be performed with higher accuracy.

  Based on these findings, the present invention has been completed.

  That is, the object is to provide a polymer electrolyte membrane, a cathode catalyst layer disposed on one side of the polymer electrolyte membrane, an anode catalyst layer disposed on the other side of the polymer electrolyte membrane, An electrolyte membrane-electrode assembly having a first gasket layer formed at an end of the cathode catalyst layer so that an area of the effective anode catalyst layer is larger than an area of the effective cathode catalyst layer Achieved by:

  Further, the object is to provide a polymer electrolyte membrane, a cathode catalyst layer disposed on one surface of the polymer electrolyte membrane, an anode catalyst layer formed on the other side of the polymer electrolyte membrane, A first gasket layer formed on at least a part of an end portion or a peripheral portion of the cathode catalyst layer and having a first adhesive layer formed on a first gas-impermeable layer; and It is also achieved by an electrolyte membrane-electrode assembly in which the area of the anode catalyst layer is larger than the area of the cathode catalyst layer.

  The electrolyte membrane-electrode assembly of the present invention can effectively prevent / suppress carbon corrosion of the cathode catalyst during start / stop / continuous operation and decomposition of the electrolyte membrane during OCV holding.

  Moreover, according to the manufacturing method of this invention, the electrolyte membrane-electrode assembly which has the above effects can be manufactured easily and correctly.

  The first of the present invention is a polymer electrolyte membrane, a cathode catalyst layer disposed on one side of the polymer electrolyte membrane, an anode catalyst layer disposed on the other side of the polymer electrolyte membrane, A first gasket layer formed at an end of the cathode catalyst layer so that an area of the effective anode catalyst layer is larger than an area of the effective cathode catalyst layer. About the body. In the present specification, the gasket layer formed and arranged at the end of the cathode catalyst layer is simply referred to as “first gasket layer”.

In the present specification, the “effective anode catalyst layer” means a region in the anode catalyst layer where a reaction of 2H ₂ → 4H ⁺ + 4e ⁻ occurs during operation (power generation), and specifically, overlaps with the gasket layer. When the anode catalyst layer region is simply referred to as the “anode catalyst layer”, it means all anode catalyst layers formed on the polymer electrolyte membrane, that is, in addition to the effective anode catalyst layer, As will be described in detail below, an overlapping portion with the second gasket layer is also included. As for the anode catalyst layer, there is a case where the second gasket layer and the anode catalyst layer do not overlap each other. In this case, the “effective anode catalyst layer” and the “anode catalyst layer” are equal. As such an example, for example, an example shown in FIG. 10 is given. More specifically, as shown in FIG. 10, the anode catalyst layer and the second gasket layer are disposed on the electrolyte membrane in a state where the opposite end portions are separated from each other. In such a case, the anode catalyst layer formed on the electrolyte membrane becomes an effective anode catalyst layer as it is.

Further, in this specification, the “effective cathode catalyst layer” means a region in the cathode catalyst layer where O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O reaction occurs during operation (power generation), specifically, The cathode catalyst layer region that does not overlap with the gasket layer, and simply referred to as “cathode catalyst layer” means all cathode catalyst layers formed on the polymer electrolyte membrane, that is, the effective cathode catalyst layer. In addition, an overlapping portion with the first gasket layer is also included.

  The electrolyte membrane-electrode assembly of the present invention (hereinafter also simply referred to as “MEA”) has at least the end portion of the cathode catalyst layer so that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer, Preferably, both ends of the cathode catalyst layer and the anode catalyst layer are sealed with a gas-impermeable gasket layer. In the present specification, the area means a geometric area and does not mean a surface area of a catalyst or the like. With such a configuration, the area of the cathode catalyst layer region facing the air existing portion downstream of the anode can be reduced, i.e., the portion where the difference between the cathode potential and the electrolyte potential is large can be significantly reduced. Can be effectively prevented / suppressed. In addition, since at least the ends of the cathode catalyst layer (preferably the ends of both the cathode catalyst layer and the anode catalyst layer) are sealed with a gas-impermeable gasket layer, the cathode catalyst in which oxygen cross-leak occurs particularly markedly. No cathode layer or such cathode catalyst layer region can be significantly reduced. Therefore, the MEA of the present invention has a structure in which there is little or no surrounding portion where only the cathode catalyst layer exists, and little or no oxygen cross leak from the cathode to the anode at the end of the cathode catalyst layer occurs. be able to. Therefore, it is possible to effectively prevent / suppress deterioration of the electrolyte membrane, which has been a serious problem in the past. Therefore, the fuel cell using the electrolyte membrane-electrode assembly of the present invention can maintain the performance during start / stop / continuous operation and OCV for a long period of time, and can also improve fuel efficiency. Furthermore, the MEA of the present invention is characterized in that the gasket layer has a configuration in which an adhesive layer is formed on a gas-impermeable gas-impermeable layer. By adopting such an adhesive, as will be described in detail in the section of the manufacturing method described later, the end portion of the catalyst layer and the gasket layer can be tightly sealed (with a low gas permeability). Therefore, according to the present invention, a highly reliable MEA can be provided.

  In the present invention, it is an essential requirement that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer. At this time, the positional relationship between the effective anode catalyst layer and the effective cathode catalyst layer is particularly limited. However, when the effective cathode catalyst layer is completely included in the effective anode catalyst layer with respect to the thickness direction of the MEA as shown in FIG. 32A; or the thickness of the MEA as shown in FIG. Any of the cases where the effective cathode catalyst layer is partially included in the effective anode catalyst layer with respect to the direction may be used, but the former case is more preferable. Similarly, the positional relationship between the catalyst layers is not particularly limited, but when the cathode catalyst layer is completely included in the anode catalyst layer in the MEA thickness direction as shown in FIG. 32A; When the cathode catalyst layer is partially included in the anode catalyst layer with respect to the thickness direction of the MEA as shown in FIG. 32B; or with respect to the thickness direction of the MEA as shown in FIG. The cathode catalyst layer may be disposed at the same position as the anode catalyst layer. However, when the cathode catalyst layer is disposed at the same position as the anode catalyst layer, the cathode catalyst layer is disposed in the anode catalyst layer. The case where the cathode catalyst layer is completely included is more preferable, and the case where the cathode catalyst layer is completely included in the anode catalyst layer is particularly preferable.

  In the present invention, the first gasket layer is formed on the polymer electrolyte membrane from the periphery of the cathode catalyst layer toward the outside so as to overlap or be in contact with the periphery of the cathode catalyst layer. With such a configuration, deterioration of the polymer electrolyte membrane can be effectively prevented / suppressed. The positional relationship between the end of the cathode catalyst layer and the first gasket layer is not particularly limited as long as the permeation of gas, particularly oxygen gas, at the end of the cathode catalyst layer can be sufficiently suppressed. For example, the first gasket layer is inserted between the cathode catalyst layer and the polymer electrolyte membrane such that the end of the first gasket layer is covered with the end of the cathode catalyst layer, and the first A positional relationship such as forming the gasket layer so as to cover the end of the cathode catalyst layer can be preferably used. In the present invention, the first gasket layer is formed so as to cover at least a part of the peripheral portion of the electrolyte membrane. From the viewpoint of improving fuel consumption due to suppression of hydrogen cross leak at the end of the anode catalyst layer. Therefore, it is preferable that the gas sealability of the peripheral portion is maintained, and therefore the first gasket layer is preferably formed in a frame shape over the entire peripheral portion of the electrolyte membrane.

  In the present invention, it is essential to form the first gasket layer at the end portion of the cathode catalyst layer, but it is preferable to further form a gasket layer at the end portion or the peripheral portion on the anode catalyst layer side. . Here, “the gasket layer is formed at the end” means that the cathode / anode catalyst layer and the first / second gasket layer overlap each other in the thickness direction or the end of the cathode / anode catalyst layer and the first / This means that the end of the second gasket layer is adjacent, and no gap is generated between the inner end of the catalyst layer and the end of the gasket layer. By taking such a structure, the effect of preventing / suppressing deterioration of the polymer electrolyte membrane can be effectively achieved. On the other hand, “form a gasket layer on the periphery” means that the anode catalyst layer and the second gasket layer do not overlap in the thickness direction. That is, as a preferred embodiment of the MEA of the present invention, in the electrolyte membrane-electrode assembly having the cathode catalyst layer, the polymer electrolyte membrane, and the anode catalyst layer, the first gasket layer is formed on at least a part of the cathode catalyst layer. And a second gasket layer is formed on at least a part of the end of the anode catalyst layer, and the first and second gasket layers have an area of the anode catalyst layer region where the second gasket layer is not formed. There is an electrolyte membrane-electrode assembly formed on the end portions of the cathode catalyst layer and the anode catalyst layer so as to be larger than the area of the cathode catalyst layer region where the gasket layer is not formed. Thus, by forming a gasket layer also at the end on the anode catalyst layer side, the effective cathode catalyst layer and the effective anode catalyst layer can be accurately and easily aligned, and the cathode during start / stop / continuous operation can be obtained. This is because carbon corrosion of the catalyst and decomposition of the electrolyte membrane during OCV retention can be effectively prevented / suppressed. In the present specification, the gasket layer formed at the end of the anode catalyst layer is simply referred to as “second gasket layer”.

  At this time, the second gasket layer is preferably formed on the polymer electrolyte membrane from the periphery of the anode catalyst layer toward the outside so as to overlap at least a part of the end of the anode catalyst layer. . However, in consideration of the ease of alignment between the cathode catalyst layer and the anode catalyst layer and the gas (hydrogen or oxygen) sealability, it is more preferable that the cathode catalyst layer and the anode catalyst layer be formed over the entire end portion of the anode catalyst layer. The positional relationship between the end of the anode catalyst layer and the second gasket layer is not particularly limited as long as the permeation of gas at the end of the anode catalyst layer can be sufficiently suppressed. For example, a second gasket layer is inserted between the anode catalyst layer and the polymer electrolyte membrane such that the end of the second gasket layer is covered with the end of the anode catalyst layer, and the second A positional relationship such as forming the gasket layer so as to cover the end of the anode catalyst layer can be preferably used. In the present invention, the second gasket layer is formed so as to cover at least a part of the periphery of the electrolyte membrane. From the viewpoint of improving fuel consumption due to suppression of hydrogen cross leak at the end of the anode catalyst layer. Therefore, it is preferable that the gas sealability of the peripheral part is maintained, and therefore the second gasket layer is also formed at the end of the anode catalyst layer as in the case of the first gasket layer, that is, It is preferable to form a frame shape over the entire periphery of the electrolyte membrane.

  The combination of forming the first and second gasket layers is not particularly limited, and may be any combination of the preferred examples. Preferably, (1) the first gasket layer is formed between the cathode catalyst layer and the polymer electrolyte membrane so that the first gasket layer is covered with the end of the cathode catalyst layer, and the second gasket layer is the anode catalyst layer. Formed between the anode catalyst layer and the polymer electrolyte membrane to be covered at the end; (2) a first gasket layer is formed to cover the end of the cathode catalyst layer; And (3) a cathode catalyst layer and a polymer electrolyte membrane so that the first gasket layer is covered with the end of the cathode catalyst layer. And a combination in which the second gasket layer is formed so as to cover the end of the anode catalyst layer. Among the above combinations, in the sense that the short circuit (contact between the anode / cathode catalyst layers) can be effectively prevented and the corrosion of the carbon hardly occurs, It is preferable that at least one of the first or second gasket layer is inserted. In this respect, the combination of (1) and (3) is preferable. Moreover, although the effect of suppressing the corrosion of carbon is somewhat inferior, the combination of the above (2) is preferably used in terms of easy production.

  In the present invention, the effective anode catalyst layer and the effective cathode catalyst layer can be easily formed by forming the first gasket layer at the end of the cathode catalyst layer, and preferably the second gasket layer at the end of the anode catalyst layer. Can be adjusted accurately and accurately. For this reason, it is not necessary to accurately align each catalyst layer in advance so that the end of each catalyst layer terminates at the same position in the thickness direction of the electrolyte membrane-electrode assembly. This is highly desirable when considering mass production. That is, the end portion of the cathode catalyst layer and the end portion of the anode catalyst layer may be terminated at substantially the same position in the thickness direction of the electrolyte membrane-electrode assembly. The position of the end of the catalyst layer may be shifted. This is because even in such a case, the gasket layer may be appropriately formed at the end of the catalyst layer so that each catalyst layer has a desired size and positional relationship. At this time, the end of the anode catalyst layer is preferably terminated beyond the end of the cathode catalyst layer in the thickness direction of the electrolyte membrane-electrode assembly. As described above, in the present invention, it is essential that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer, and thus the cathode catalyst layer is previously made smaller than the size of the anode catalyst layer. Therefore, the amount of the catalyst and electrolyte to be used can be reduced, and the overlap with the gasket layer portion can be reduced, which is economically preferable.

  In the electrolyte membrane-electrode assembly of the present invention, the end of the catalyst layer and the gasket layer, in particular, the end of the gas-impermeable layer described in detail below, do not need to be exactly aligned, and a certain amount of gap exists. May be. Even in such a case, if the gap is filled with the gas-impermeable adhesive layer, it functions similarly as a gasket layer, and the effects of the present invention can be sufficiently exhibited. That is, in a preferred embodiment of the electrolyte membrane-electrode assembly of the present invention, the inner end portion of the first or second gas-impermeable layer is the end portion of the catalyst layer with respect to the thickness direction of the electrolyte membrane-electrode assembly. And an adhesive layer is disposed between the inner end of the gas-impermeable layer and the outer end of the catalyst layer.

  In the present invention, it is preferable that the second gasket layer is further formed at the end of the anode catalyst layer. Thereby, the sizes of the anode catalyst layer and the cathode catalyst layer can be easily controlled; the alignment of each catalyst layer is easy; the end of the catalyst layer is sealed with the gasket layer, and the downstream of the anode catalyst layer at the start-up time The cathode catalyst layer region that faces the air-existing portion of the catalyst and the cathode catalyst layer region that faces the region where there is no anode catalyst layer and hydrogen is not oxidized during continuous operation can be reduced, and the difference between the cathode potential and the electrolyte potential increases. Therefore, it is possible to effectively prevent / suppress carbon corrosion of the cathode catalyst layer; and to seal the periphery where only the anode catalyst layer exists without the cathode catalyst layer with the gasket layer. This suppresses the cross-leakage of oxygen from the cathode to the anode, which tends to occur remarkably at the end of the cathode catalyst layer, and For the production of hydrogen peroxide on the anode side can be suppressed significantly, it is possible to effectively prevent / suppress the deterioration of the electrolyte membrane; benefits such as can be achieved. At this time, it is preferable that the end portion of the catalyst layer and the end portion of the gasket layer are overlapped. In this case, with respect to the cathode catalyst layer side, the overlapping portion of the end portion of the cathode catalyst layer and the first gasket layer is the same. The length [A (mm) in FIG. 7] is preferably more than 0 (A> 0). More preferably, the length A is 0.2 to 2.0 mm, most preferably 0.5 to 1.5 mm. Further, regarding the anode catalyst layer side, the length [B (mm) in FIG. 7] of the overlapping portion between the end portion of the anode catalyst layer and the second gasket layer is more than 0 and 2 mm or less (0 < B ≦ 2) is preferred. More preferably, the length B is 0.2 to 2.0 mm, most preferably 0.5 to 1.5 mm. Further, the distance between the outer end portion of the cathode catalyst layer and the outer end portion of the anode catalyst layer that terminates beyond the outer end portion of the cathode catalyst layer in the thickness direction of the electrolyte membrane-electrode assembly [C in FIG. mm)] is preferably larger than B (B <C). More preferably, the length C is 2.1 to 4.0 mm, most preferably 2.5 to 3.5 mm. If A and B are within the above ranges, sufficient sealing performance at the end of the catalyst layer can be secured.

  In the electrolyte membrane-electrode assembly of the present invention, the distance between the outer end portion of the cathode catalyst layer and the inner end portion of the second gasket layer with respect to the thickness direction of the electrolyte membrane-electrode assembly [X (mm in FIG. )] Is preferably greater than 0 (X> 0). More preferably, the length X is 0.1 to 3.8 mm, most preferably 1.0 to 3.0 mm. If it is in such a range, as will be described in detail later, a hot press when joining each layer of MEA, a fastening pressure when assembling a battery (compression pressure applied when MEA is sandwiched between separators), etc. The deterioration over time can be effectively suppressed / prevented, and the phenomenon that the film is crushed by the compressive stress and the cathode catalyst layer and the anode catalyst layer come into contact with each other can be effectively suppressed / prevented.

  Further, in the electrolyte membrane-electrode assembly of the present invention, the first gasket layer and / or the second gasket layer may overlap with the end of the cathode / anode catalyst layer or the end of the cathode / anode catalyst layer. It is preferable that the contacting portion has at least a function of suppressing gas permeability. By providing the gas permeation suppressing / inhibiting function to the gasket layer in this manner, gas sealing performance at the overlapping portion of the gasket layer end portion and the catalyst layer end portion (especially sealing performance against oxygen gas on the cathode side) can be achieved. It can be improved further. The method for imparting the gas permeation suppression / inhibition function to the gasket layer is not particularly limited. For example, as described in detail below, in the method of forming a gasket layer from a gas impermeable layer and an adhesive layer, (1) When joining the catalyst layer and the electrolyte membrane by hot pressing, after selectively placing a sheet having a predetermined thickness on the overlapping portion between the end portion of the catalyst layer and the gasket layer, thermocompression bonding is performed and the overlapping portion is applied. (2) In the overlapping portion, the thickness of the adhesive layer or the amount of the adhesive contained in the adhesive layer is appropriately set in the overlapping portion. (3) A gasket layer (gas-impermeable layer and / or adhesive layer) of the overlapping portion is impregnated with a resin in advance. And keep methods; (4) a method of preliminarily densely form the catalyst layer of the overlapping portion is preferably used. However, the method for imparting the gas permeation suppression / inhibition function to the gasket layer is not limited to the above method, and other known methods may be applied.

  The electrolyte membrane-electrode assembly of the present invention can be produced in the same manner as a known method or by using a suitably modified method. Specifically, on the polymer electrolyte membrane, a cathode catalyst layer, an anode catalyst layer, a first gasket layer, and, if necessary, a second gasket layer are arranged in an appropriate arrangement, for example, the arrangement described above. A sequential forming method can be used.

  Accordingly, in the second aspect of the present invention, after the first gasket layer is formed on the cathode catalyst layer side surface of the polymer electrolyte membrane, the end of the gasket layer and the end of the cathode catalyst layer overlap. A step of further forming a cathode catalyst layer; and, after forming the second gasket layer on the surface of the polymer electrolyte membrane on the anode catalyst layer side, the end of the gasket layer and the end of the anode catalyst layer overlap each other. A step of further forming an anode catalyst layer, and the first gasket layer and the second gasket layer are formed so that an area of the effective anode catalyst layer is larger than an area of the effective cathode catalyst layer. The present invention relates to a method for manufacturing an MEA according to the present invention.

  In the third aspect of the present invention, a cathode catalyst layer is formed on the cathode catalyst layer side surface of the polymer electrolyte membrane, and then a first gasket layer is further formed so as to cover the end of the cathode catalyst layer. And, after forming the anode catalyst layer on the anode catalyst layer side surface of the polymer electrolyte membrane, further forming a second gasket layer so as to cover the end of the anode catalyst layer, and The first gasket layer and the second gasket layer are related to the MEA manufacturing method of the present invention, characterized in that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer. is there.

  Furthermore, in the fourth aspect of the present invention, after the first gasket layer is formed on the surface of the polymer electrolyte membrane on the cathode catalyst layer side, the end of the gasket layer and the end of the cathode catalyst layer are overlapped. A step of further forming a cathode catalyst layer; and, after forming an anode catalyst layer on the surface of the polymer electrolyte membrane on the anode catalyst layer side, further forming a second gasket layer so as to cover the end of the anode catalyst layer And the first gasket layer and the second gasket layer are formed such that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer. The present invention relates to an MEA manufacturing method.

  According to the method of the present invention, the cathode catalyst layer, the first gasket layer, the anode catalyst layer, and, if necessary, the second gasket layer can be accurately and easily arranged in a desired order. In addition, by disposing the first gasket layer and the second gasket layer at the ends of the cathode catalyst layer and the anode catalyst layer, respectively, the effective cathode catalyst layer and the effective anode catalyst layer can be accurately adjusted to have desired areas. Can be specified.

  In the method of the present invention, the first gasket layer is formed at the end of the cathode catalyst layer, and preferably the second gasket layer is formed at the end of the anode catalyst layer, so that the alignment of each catalyst layer needs to be accurate. Is not necessarily. That is, the end of the cathode catalyst layer and the end of the anode catalyst layer may end at substantially the same position in the thickness direction of the electrolyte membrane-electrode assembly. The position of the end of the catalyst layer may be shifted. This is because even in such a case, the gasket layer may be appropriately formed at the end of the catalyst layer so that each catalyst layer is in a desired size and position. At this time, the end of the anode catalyst layer is preferably terminated beyond the end of the cathode catalyst layer in the thickness direction of the electrolyte membrane-electrode assembly. As described above, in the present invention, it is essential that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer, and thus the cathode catalyst layer is previously made smaller than the size of the anode catalyst layer. Therefore, the amount of the catalyst and electrolyte to be used can be reduced, and the overlap with the gasket layer portion can be reduced, which is economically preferable.

  For example, in the second method of the present invention, when the end portion of the cathode catalyst layer and the end portion of the anode catalyst layer are terminated at substantially the same position in the thickness direction of the electrolyte membrane-electrode assembly, The ends of the cathode catalyst layer and the anode catalyst layer have a structure as shown in FIG. In such a case, since a gasket layer exists between the cathode and anode catalyst layers, the edges of the catalyst layers come into contact with each other when the gas diffusion layer is pressed later or when the fuel cell stack is laminated. There is a further advantage that short circuit of the part can be prevented. In the third method of the present invention, when the end of the cathode catalyst layer and the end of the anode catalyst layer are terminated at substantially the same position with respect to the thickness direction of the electrolyte membrane-electrode assembly, The ends of the cathode catalyst layer and the anode catalyst layer have a structure as shown in FIG. In such a method, since the gasket layer is provided after the formation of the catalyst layer, the manufacturing process is simpler than the method of FIG. 4 and the control of the effective catalyst layer region is performed accurately and easily. Furthermore, there is an advantage that the periphery of the catalyst layer can be tightly sealed (with a low gas permeability) by the gasket layer. Furthermore, in the fourth method of the present invention, when the end of the cathode catalyst layer and the end of the anode catalyst layer are terminated at substantially the same position in the thickness direction of the electrolyte membrane-electrode assembly, The ends of the cathode catalyst layer and the anode catalyst layer have a structure as shown in FIG. The structure as described above is a combination of the structures shown in the second and third aspects of the present invention. That is, since a gasket layer exists between the cathode and anode catalyst layers, a gas diffusion layer or the like is pressed later. In addition, the edge of the anode catalyst layer can be prevented and the anode catalyst layer side is sealed with a gasket layer, so that the effective catalyst layer area on the anode catalyst layer side can be easily controlled, so that the effective anode catalyst layer area can be further increased. It can be surely set larger than the area of the effective cathode catalyst layer. The reverse pattern of FIG. 6, that is, the first gasket layer is formed so as to cover the end portion of the cathode catalyst layer, and the second gasket layer is covered with the end portion of the anode catalyst layer. It is also possible to form the anode catalyst layer and the polymer electrolyte membrane. However, in such a method, there is a cathode catalyst layer portion facing the overlapping portion of the second gasket layer and the anode catalyst layer and in contact with the electrolyte membrane. For this reason, the difference between the cathode potential and the electrolyte potential is increased, a carbon corrosion reaction occurs, and the corrosion of carbon black, which is a conductive carrier in the cathode catalyst layer, progresses, and the catalytic activity may be reduced. Such a method is less preferred.

  Further, in the second method of the present invention, when the positions of the end portions of the cathode catalyst layer and the anode catalyst layer are shifted with respect to the thickness direction of the electrolyte membrane-electrode assembly, The ends of the catalyst layer and the anode catalyst layer have a structure as shown in FIG. In such a case, even when the end portions of the catalyst layers are not accurately aligned, the area of each effective catalyst layer can be freely set by the arrangement of the gasket layer, and the manufacturing process is simpler. In addition to the advantages, since the gasket layer is present between the cathode and anode catalyst layers, there is an additional advantage that short-circuiting of the edge portion can be prevented when the gas diffusion layer or the like is later pressed or laminated as a fuel cell stack. In the third method of the present invention, when the position of the end of the cathode catalyst layer and the end of the anode catalyst layer are shifted with respect to the thickness direction of the electrolyte membrane-electrode assembly, The ends of the catalyst layer and the anode catalyst layer have a structure as shown in FIG. In the same way as described in the second method, in addition to the advantage of simplifying the manufacturing process, such a method is provided with a gasket layer after forming the catalyst layer. The manufacturing process is simple, the effective catalyst layer region can be controlled accurately and easily, and the catalyst layer can be tightly sealed (with low gas permeability) by the gasket layer. There is. Furthermore, in the fourth method of the present invention, when the positions of the end of the cathode catalyst layer and the end of the anode catalyst layer are shifted with respect to the thickness direction of the electrolyte membrane-electrode assembly, The ends of the catalyst layer and the anode catalyst layer have a structure as shown in FIG. As described in the second method, the structure as described above has an advantage of simplifying the manufacturing process and a gasket layer between the cathode and anode catalyst layers. In addition, it is possible to prevent a short circuit at the edge when stacking as a fuel cell stack, and the anode catalyst layer side is sealed with a gasket layer, so that the effective catalyst layer area on the anode catalyst layer side can be easily controlled. Therefore, the area of the effective anode catalyst layer can be set more reliably than the area of the effective cathode catalyst layer.

The method of the present invention, particularly the second to fourth aspects of the present invention when the positions of the end portions of the cathode catalyst layer and the anode catalyst layer are shifted with respect to the thickness direction of the electrolyte membrane-electrode assembly. In the method, it is preferred that there is as little gap as possible between the end of the cathode catalyst layer and the end of the effective anode catalyst layer (eg, “X” is close to 0 in FIG. 7). If such a gap portion exists, even if electrons (e ⁻ ) and protons (H ⁺ ) generated in this portion move to the cathode catalyst layer side, the area of the effective anode catalyst layer is the effective cathode catalyst layer. This is because the protons and electrons cannot efficiently react with oxygen on the cathode side, and the catalytic action does not work effectively. In consideration of this, the width (X) of the gap portion between the end portion of the cathode catalyst layer and the end portion of the effective anode catalyst layer is preferably 1 cm or less, more preferably 3 mm or less.

  In the present invention, the catalyst component used in the cathode catalyst layer is not particularly limited as long as it has a catalytic action in the oxygen reduction reaction, and known catalysts can be used in the same manner. Further, the catalyst component used in the anode catalyst layer is not particularly limited as long as it has a catalytic action for the oxidation reaction of hydrogen, and a known catalyst can be used in the same manner. Specifically, it is selected from platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum and the like, and alloys thereof. Is done. Among these, those containing at least platinum are preferably used in order to improve catalyst activity, poisoning resistance to carbon monoxide and the like, heat resistance, and the like. The composition of the alloy is preferably 30 to 90 atomic% for platinum and 10 to 70 atomic% for the metal to be alloyed, depending on the type of metal to be alloyed. The composition of the alloy when the alloy is used as a cathode catalyst varies depending on the type of metal to be alloyed and can be appropriately selected by those skilled in the art, but platinum is 30 to 90 atomic%, and other metals to be alloyed are 10 It is preferable to set it to -70 atomic%. In general, an alloy is a generic term for an element obtained by adding one or more metal elements or non-metal elements to a metal element and having metallic properties. The alloy structure consists of a eutectic alloy, which is a mixture of component elements that form separate crystals, a component element that completely dissolves into a solid solution, and a component element that is an intermetallic compound or a compound of a metal and a nonmetal. There is what is formed, and any may be used in the present application. At this time, the catalyst component used for the cathode catalyst layer and the catalyst component used for the anode catalyst layer can be appropriately selected from the above. In the following description, unless otherwise specified, the description of the catalyst component for the cathode catalyst layer and the anode catalyst layer has the same definition for both, and is collectively referred to as “catalyst component”. However, the catalyst components for the cathode catalyst layer and the anode catalyst layer do not need to be the same, and are appropriately selected so as to exhibit the desired action as described above.

  The shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components can be used, but the catalyst component is preferably granular. At this time, the smaller the average particle diameter of the catalyst particles used in the catalyst ink, the higher the effective electrode area where the electrochemical reaction proceeds, which is preferable because the oxygen reduction activity is also high, but in practice the average particle diameter is too small. On the other hand, a phenomenon in which the oxygen reduction activity decreases is observed. Therefore, the average particle diameter of the catalyst particles contained in the catalyst ink is preferably 1 to 30 nm, more preferably 1.5 to 20 nm, still more preferably 2 to 10 nm, and particularly preferably 2 to 5 nm. It is preferably 1 nm or more from the viewpoint of easy loading, and preferably 30 nm or less from the viewpoint of catalyst utilization. The “average particle diameter of the catalyst particles” in the present invention is the average value of the particle diameter of the catalyst component determined from the crystallite diameter or transmission electron microscope image obtained from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction. Can be measured.

  In the present invention, the catalyst particles described above are included in the catalyst ink as an electrode catalyst supported on a conductive carrier.

  The conductive carrier may have any specific surface area for supporting the catalyst particles in a desired dispersed state and has sufficient electronic conductivity as a current collector. The main component is carbon. Preferably there is. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. In the present invention, “the main component is carbon” refers to containing a carbon atom as a main component, and is a concept including both a carbon atom only and a substantially carbon atom. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. In addition, being substantially composed of carbon atoms means that mixing of impurities of about 2 to 3% by mass or less is allowed.

The BET specific surface area of the conductive carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m ² / g, more preferably 80 to 1200 m ² / g. Is good. If the specific surface area is less than 20 m ² / g, the dispersibility of the catalyst component and the polymer electrolyte in the conductive support may be reduced, and sufficient power generation performance may not be obtained, and the specific surface area exceeds 1600 m ² / g. In addition, the effective utilization rate of the catalyst component and the polymer electrolyte may decrease instead.

  Further, the size of the conductive carrier is not particularly limited, but from the viewpoint of controlling the ease of loading, the catalyst utilization, and the thickness of the electrode catalyst layer within an appropriate range, the average particle size is 5 to 200 nm. The thickness is preferably about 10 to 100 nm.

  In the electrode catalyst in which the catalyst component is supported on the conductive support, the supported amount of the catalyst component is preferably 10 to 80% by mass, more preferably 30 to 70% by mass with respect to the total amount of the electrode catalyst. Good. If the loading amount exceeds 80% by mass, the degree of dispersion of the catalyst component on the conductive support is lowered, and although the loading amount is increased, the improvement in power generation performance is small and the economic advantage may be lowered. On the other hand, if the loading amount is less than 10% by mass, the catalytic activity per unit mass is lowered, and a large amount of electrode catalyst is required to obtain the desired power generation performance, which is not preferable. The amount of the catalyst component supported can be examined by inductively coupled plasma emission spectroscopy (ICP).

  The cathode catalyst layer / anode catalyst layer (hereinafter also simply referred to as “catalyst layer”) of the present invention contains a polymer electrolyte in addition to the electrode catalyst. The polymer electrolyte is not particularly limited and a known one can be used, but any member having at least high proton conductivity may be used. The polymer electrolyte that can be used in this case is roughly classified into a fluorine-based electrolyte that contains fluorine atoms in the whole or a part of the polymer skeleton and a hydrocarbon-based electrolyte that does not contain fluorine atoms in the polymer skeleton.

  Specific examples of the fluorine electrolyte include perfluorocarbon sulfonic acids such as Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Polymer, polytrifluorostyrene sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene A preferred example is a fluoride-perfluorocarbon sulfonic acid-based polymer.

  Specific examples of the hydrocarbon electrolyte include polysulfone sulfonic acid, polyaryl ether ketone sulfonic acid, polybenzimidazole alkyl sulfonic acid, polybenzimidazole alkyl phosphonic acid, polystyrene sulfonic acid, polyether ether ketone sulfonic acid, polyphenyl. A suitable example is sulfonic acid.

  The polymer electrolyte preferably contains a fluorine atom because of its excellent heat resistance and chemical stability. Among them, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.) Fluorine electrolytes such as Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) are preferred.

  The catalyst component can be supported on the conductive carrier by a known method. For example, known methods such as impregnation method, liquid phase reduction support method, evaporation to dryness method, colloid adsorption method, spray pyrolysis method, reverse micelle (microemulsion method) can be used. Alternatively, a commercially available electrode catalyst may be used.

  In the method of the present invention, the catalyst ink comprising the electrode catalyst, the polymer electrolyte and the solvent as described above is applied to the surface of the polymer electrolyte membrane (or the surface of the polymer electrolyte membrane with the gasket layer partially covered). By applying, a catalyst layer is formed. In this case, the solvent is not particularly limited, and usual solvents used for forming the catalyst layer can be used in the same manner. Specifically, water, lower alcohols such as cyclohexanol, ethanol and 2-propanol can be used. Also, the amount of solvent used is not particularly limited, and the same amount as known can be used. In the catalyst ink, the electrode catalyst has a desired action, that is, hydrogen oxidation reaction (anode side) and oxygen reduction reaction. Any amount may be used as long as it can sufficiently exert the action of catalyzing (cathode side). It is preferable that the electrode catalyst is present in the catalyst ink in an amount of 5 to 30% by mass, more preferably 9 to 20% by mass.

  The catalyst ink of the present invention may contain a thickener. The use of a thickener is effective when the catalyst ink cannot be successfully applied onto a transfer mount. The thickener that can be used in this case is not particularly limited, and a known thickener can be used. Examples thereof include glycerin, ethylene glycol (EG), polyvinyl alcohol (PVA), and propylene glycol (PG). Of these, propylene glycol (PG) is preferably used. By using propylene glycol (PG), the boiling point of the catalyst ink increases and the solvent evaporation rate decreases. For this reason, for example, when a catalyst layer is formed on an electrolyte membrane by a transfer method, first, when a catalyst ink is applied and dried using a screen printer or the like on a transfer mount different from the membrane, By adding PG to the solvent, the solvent evaporation rate in the applied catalyst ink is suppressed, and it is possible to suppress / prevent cracks from occurring in the catalyst layer after the drying process (see FIG. 33). By transferring the catalyst layer with few cracks to the film in this way, mechanical stress concentration on the film in the OCV durability test is alleviated, and as a result, the durability of the MEA can be improved. The amount of the thickener added when the thickener is used is not particularly limited as long as it does not interfere with the above effect of the present invention, but is preferably 5 to 65 with respect to the total mass of the catalyst ink. % By mass. In particular, the amount of PG added when using PG as a thickener is preferably 10 to 30% by mass with respect to the total mass of the catalyst ink.

  The catalyst ink of the present invention is not particularly limited in its preparation method as long as an electrode catalyst, an electrolyte and a solvent, and if necessary, a water-repellent polymer and / or a thickener are appropriately mixed. For example, a catalyst ink can be prepared by adding an electrolyte to a polar solvent, heating and stirring the mixed solution to dissolve the electrolyte in the polar solvent, and then adding an electrode catalyst thereto. Alternatively, after the electrolyte is once dispersed / suspended in a solvent, the dispersion / suspension may be mixed with an electrode catalyst to prepare a catalyst ink. In addition, a commercially available electrolyte solution (for example, DuPont Nafion solution: Nafion dispersed / suspended at a concentration of 5 wt% in 1-propanol) in which the electrolyte is previously prepared in the above other solvent is used as it is. May be used in the method.

  Each catalyst layer is formed by applying the catalyst ink as described above on the polymer electrolyte membrane or on the polymer electrolyte membrane while covering a part of the gasket layer. At this time, the conditions for forming the cathode / anode catalyst layer on the polymer electrolyte membrane are not particularly limited, and can be used in the same manner as known methods or appropriately modified. For example, the catalyst ink is applied onto the polymer electrolyte membrane so that the thickness after drying is 5 to 20 μm, and is 25 to 150 ° C., more preferably 60 to 120 ° C. in a vacuum dryer or under reduced pressure. And drying for 5 to 30 minutes, more preferably for 10 to 20 minutes. In addition, in the said process, when the thickness of a catalyst layer is not enough, the said application | coating and drying process is repeated until it becomes desired thickness.

  In the present invention, the gasket layer may be impermeable to gas, particularly oxygen or hydrogen gas. In general, the gasket layer is not bonded to the end of the polymer electrolyte membrane or the cathode / anode catalyst layer. It is composed of a target adhesive layer and an impermeable layer made of a gas impermeable material.

  At this time, the material constituting the impermeable layer is not particularly limited as long as it is impermeable to oxygen and hydrogen gas when formed into a film. Specific examples include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF).

  In addition, the material that can be used for the adhesive layer is not particularly limited as long as it can adhere the polymer electrolyte membrane or the cathode / anode catalyst layer and the gasket layer closely, but this adhesive layer also has gas permeability. Preferably it is low. Employing such an adhesive layer is preferable because the adhesive layer can also function as a gas-impermeable layer in the manufactured MEA. Specifically, hot melt adhesives such as polyolefin, polypropylene and thermoplastic elastomer, acrylic adhesives, olefin adhesives such as polyester and polyolefin can be used. Among these, as a material constituting the adhesive layer, a hot melt adhesive is preferable. Since the hot melt adhesive does not soften at room temperature, it has an advantage that the alignment in the gasket layer arranging step at the time of manufacture is simple. Moreover, compared with a thermosetting adhesive, it has the advantage that it can be easily manufactured in a short time. Further, depending on the type of the adhesive layer for adhering the gasket layer to the end portion of the catalyst layer, a gap may be formed between the catalyst layer and the gasket layer when the gasket layer is sealed. For example, if such a gap occurs on the cathode side, oxygen gas cross-leakage occurs from this gap, causing oxidation deterioration of the electrolyte membrane due to the formation of hydrogen peroxide, and the meaning of providing the gasket layer is diminished. There is a fear. On the other hand, when a hot-melt adhesive layer is employed as the adhesive, the end portion of the catalyst layer can be sealed with the adhesive layer softened by the hot press process during sealing. Therefore, the possibility that a gap is generated when the end of the catalyst layer is sealed by the gasket layer is reduced, and a highly reliable MEA can be manufactured. At this time, the softening point of the hot-melt adhesive is not particularly limited and can be appropriately selected in consideration of the material used for the impermeable layer and the catalyst layer. Preferably, the hot melt adhesive has a softening point in a temperature range that is higher than the operating temperature and does not damage the electrolyte membrane or the catalyst layer during production. As a result, the adhesive does not soften even when it is actually installed in a fuel cell, and maintains a tight seal (low gas permeability) between the end of the catalyst layer and the gasket layer. As described in detail below, even when heat is applied in the production of an MEA incorporating a membrane and an electrolyte membrane, the electrolyte membrane and the catalyst layer are not damaged (the performance is not degraded or destroyed). ) Can produce MEA. Specifically, the melting point of the hot melt adhesive is 50 to 170 ° C., most preferably 90 to 150 ° C.

  The formation method in particular of a gasket layer is not restrict | limited, A well-known method can be used. For example, after applying the adhesive to a thickness of 5 to 30 μm on the polymer electrolyte membrane or on the polymer electrolyte membrane while covering the end portion of the catalyst layer, the gas non-existence as described above is applied. A method can be used in which a transparent material is applied to a thickness of 10 to 200 μm and cured by heating at 50 to 170 ° C. for 10 seconds to 10 minutes. Alternatively, after a gas-impermeable material is formed into a sheet in advance, an adhesive is applied to the impermeable film to form a gasket layer, which is then applied to the polymer electrolyte membrane or a part of the gasket layer. It may be bonded onto the polymer electrolyte membrane while coating. At this time, the thickness of the impermeable layer is not particularly limited, but is preferably 15 to 40 μm, and the adhesive layer is also not particularly limited, but is preferably 10 to 25 μm.

  The polymer electrolyte membrane used in the MEA of the present invention is not particularly limited, and examples thereof include a membrane made of the same polymer electrolyte as that used for the electrode catalyst layer. In addition, various Nafion (registered trademark of DuPont) manufactured by DuPont and perfluorosulfonic acid membranes represented by Flemion, ion exchange resins manufactured by Dow Chemical, ethylene-tetrafluoroethylene copolymer resin membrane, trifluoro Fluoropolymer electrolytes such as resin membranes based on styrene, hydrocarbon resin membranes with sulfonic acid groups, and other commonly available solid polymer electrolyte membranes and polymer microporous membranes A membrane impregnated with a liquid electrolyte, a membrane in which a porous body is filled with a polymer electrolyte, or the like may be used. The polymer electrolyte used for the polymer electrolyte membrane and the polymer electrolyte used for each electrode catalyst layer may be the same or different, but the adhesion between each electrode catalyst layer and the polymer electrolyte membrane From the viewpoint of improving the properties, it is preferable to use the same one.

  The thickness of the polymer electrolyte membrane may be appropriately determined in consideration of the properties of the obtained MEA, but is preferably 5 to 300 μm, more preferably 10 to 200 μm, and particularly preferably 15 to 100 μm. From the viewpoint of strength during film formation and durability during MEA operation, it is preferably 5 μm or more, and from the viewpoint of output characteristics during MEA operation, it is preferably 300 μm or less.

  The polymer electrolyte membrane includes polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) in addition to the above-described fluorine-based polymer electrolyte and membranes made of hydrocarbon resins having sulfonic acid groups. For example, a porous thin film formed from a material impregnated with an electrolyte component such as phosphoric acid or ionic liquid may be used.

  In the present invention, as described above, the first gasket layer, more preferably the second gasket layer, is preferably such that an adhesive layer is formed on the gas-impermeable layer. As an MEA production method that can be particularly preferably used, the cathode catalyst layer and the anode catalyst layer are formed on the respective surfaces of the polymer electrolyte membrane so that the area of the anode catalyst layer is larger than the area of the cathode catalyst layer. Catalyst layer forming step; a first gasket layer in which a first adhesive layer is formed on a first gas-impermeable layer, the first adhesive layer and the polymer electrolyte membrane facing each other. A second gasket layer, which is disposed on at least a part of the periphery of the polymer electrolyte membrane and has a second adhesive layer formed on the second gas-impermeable layer, includes the second adhesive layer and the second adhesive layer. With polymer electrolyte membrane A gasket layer disposing step that is disposed on at least a part of an end portion or a peripheral portion of the polymer electrolyte membrane so as to face each other; and by pressing the laminate obtained by the catalyst layer forming step and the gasket layer disposing step. There is a method for producing an electrolyte membrane-electrode assembly, the method comprising the step of adhering the first gasket layer and the second gasket layer to the polymer electrolyte membrane. The fifth aspect is configured.

  The fifth aspect of the present invention will be described below.

  First, the cathode catalyst layer and the anode catalyst layer are formed on each surface of the polymer electrolyte membrane so that the area of the anode catalyst layer is larger than the area of the cathode catalyst layer (catalyst layer forming step). In this step, the catalyst ink (catalyst component, conductive carrier, polymer electrolyte, etc.) used for each catalyst layer, the electrolyte membrane, and the catalyst method for the electrolyte membrane are the same as in the second and third aspects. Therefore, the description is omitted here.

  Next, in the manufacturing method of the present invention, a gasket layer arranging step of arranging a gasket layer is performed.

  Note that either the catalyst layer forming step of forming the catalyst layer and the gasket layer arranging step of arranging the gasket layer may be performed first. In some cases, the catalyst layer forming step and the gasket layer arranging step may be performed simultaneously.

  In the arrangement step of the production method of the present invention described above, any arrangement of the first gasket layer around the cathode catalyst layer and the second gasket layer around the anode catalyst layer is possible. May be performed. That is, in the arrangement step, for example, the arrangement of the gasket layer is such that the end of the first gasket layer and the end of the cathode catalyst layer substantially coincide with each other, and the end of the second gasket layer and the anode catalyst layer It may be performed so that the end portion substantially matches (the pattern shown in FIG. 11). According to such an arrangement, the seal between the catalyst layer and the gasket layer is performed with the highest accuracy, and the gap generated between them can be minimized. When the gasket layer is arranged so that the end of the catalyst layer and the end of the gasket layer substantially coincide with each other as described above, at least a part of the thickness of the adhesive layer formed on the gasket layer is reduced. It is preferable to provide a thin part that is thinner than other parts (pattern shown in FIG. 12). According to such a form, the protrusion of the adhesive layer from the gasket layer is suppressed, and the yield at the time of manufacturing the MEA can be improved. Moreover, when it is desired to further exert the effect of suppressing the protrusion of the adhesive layer as described above, an exposed portion where the adhesive layer is not present is preferably provided on at least a part of the gasket layer (pattern shown in FIG. 13). .

  On the other hand, the gasket layer may be disposed with a certain gap between the end of the catalyst layer. When the gasket layer is arranged with a certain distance from the end portion of the catalyst layer as described above, for example, a part of the adhesive layer formed on the gasket layer (in particular, the inner end portion (catalyst) The layer side)) may be thicker than the other parts (pattern shown in FIG. 14). According to such a form, even if there is a certain gap between the gasket layer and the end of the catalyst layer in the arrangement process, the thick adhesive layer is used to block this gap in the bonding process. As an adhesive layer, the sealing between the gasket layer and the end of the catalyst layer can be performed more reliably. Such a form is particularly effective when a hot melt adhesive is employed as the adhesive.

  Alternatively, a plurality of adhesive layers may be formed in a convex shape in the direction from the outer end portion (outside of the MEA) to the inner end portion (catalyst layer side) of the gasket layer (pattern shown in FIG. 15). Such a plurality of hot-melt adhesive layers are melted and integrated by hot pressing in the bonding process. Even with such a configuration, even if there is a certain gap between the gasket layer and the end of the catalyst layer in the arrangement process, the sealing between the gasket layer and the end of the catalyst layer is more reliably performed. It can be broken.

  As described above, even if there is a gap between the end of the catalyst layer and the gasket layer in the gasket layer arranging step, the gap is formed by an adhesive (particularly a hot-melt adhesive) by pressing in the bonding step. ) To seal between the end of the catalyst layer and the gasket layer (see FIG. 16). Therefore, according to such a manufacturing method, since it is not necessary to arrange | position a gasket layer so that the gasket layer and the edge part of a catalyst layer may correspond exactly, manufacture more simple is attained.

  When the gasket layer arranging step is performed after the catalyst layer forming step, as shown in FIG. 17, the gasket layer arranging step in the gasket layer arranging step is aligned between the catalyst layer forming step and the gasket layer arranging step. You may further perform the guide member arrangement | positioning process which arrange | positions a guide member. By further performing such a guide member arranging step, the gasket layer can be arranged more accurately and a highly reliable MEA can be manufactured. The guide member arranged in the guide member arranging step is removed before the bonding step after the gasket layer is arranged in the gasket layer arranging step.

  The specific form of the constituent material of the guide member is not particularly limited. However, it is preferable to use a material that is less likely to poison the polymer electrolyte membrane or the catalyst layer. Examples of such a material include polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), and polyfluoride. Fluorine resin such as vinylidene chloride (PVDF), acrylic resin, epoxy resin, phenol resin, polyvinyl chloride, glass, wood, metal, etc. can be exemplified. Of course, the guide member may be made of other materials.

  There is no restriction | limiting in particular also about the thickness of a guide member, The thickness which can guide the arrangement | positioning of a gasket layer efficiently can be set suitably. As an example, the thickness of the guide member is preferably about 100 μm to 2 cm, more preferably about 100 μm to 3 mm. However, in some cases, a guide member with a thickness outside this range may be used.

  In the production method of the present invention, an adhesion step is performed after the catalyst layer forming step and the gasket layer arranging step. In the said adhesion process, the laminated body obtained by the catalyst layer formation process and the arrangement | positioning process is pressed. Thereby, a gasket layer and a polymer electrolyte membrane are adhere | attached through the adhesive bond layer of a gasket layer.

  There is no restriction | limiting in particular also about the press conditions in an adhesion | attachment process, According to the kind etc. of the adhesive agent used, a conventionally well-known knowledge can be referred suitably. However, as an example of preferable conditions, the pressing pressure is preferably 0.05 to 4.0 MPa, more preferably 0.1 to 2.0 MPa, and the pressing time is preferably 1 second to 10 minutes, more preferably. 10 seconds to 1 minute. When a hot press type adhesive is employed as the adhesive, it is preferable to perform hot pressing in the bonding step, and the pressing temperature at this time is preferably 50 to 170 ° C, more preferably 90 to 150 ° C. .

  In the above description, the method of directly forming the anode / cathode catalyst layer or the gasket layer on the polymer electrolyte membrane by directly applying the catalyst ink has been described. However, the MEA of the present invention is not limited to the transfer method or the like. It may be manufactured by this method. The production method in such a case is not particularly limited, and a known transfer method can be used in the same manner or with appropriate modification. For example, the following method can be used. That is, the catalyst ink as prepared above is applied and dried on a transfer mount to form an electrode catalyst layer. At this time, as the transfer mount, a known sheet such as a polyester sheet such as a PTFE (polytetrafluoroethylene) sheet or a PET (polyethylene terephthalate) sheet can be used. The transfer mount is appropriately selected according to the type of catalyst ink to be used (particularly, a conductive carrier such as carbon in the ink). In the above process, the thickness of the electrode catalyst layer is not particularly limited as long as it can sufficiently exhibit the catalytic action of the hydrogen oxidation reaction (anode side) and the oxygen reduction reaction (cathode side). Thickness can be used. Specifically, the thickness of the electrode catalyst layer is 1 to 30 μm, more preferably 1 to 20 μm. The method for applying the catalyst ink onto the transfer mount is not particularly limited, and a known method such as a screen printing method, a deposition method, or a spray method can be similarly applied. Also, the drying conditions of the applied electrode catalyst layer are not particularly limited as long as the polar solvent can be completely removed from the electrode catalyst layer. Specifically, the catalyst ink coating layer (electrode catalyst layer) is dried in a vacuum dryer at room temperature to 100 ° C., more preferably 50 to 80 ° C., for 30 to 60 minutes. At this time, if the thickness of the catalyst layer is not sufficient, the coating and drying process is repeated until a desired thickness is obtained. Next, after sandwiching the polymer electrolyte membrane between the electrode catalyst layers thus produced, hot pressing is performed on the laminate. At this time, the hot press conditions are not particularly limited as long as the electrode catalyst layer and the polymer electrolyte membrane can be sufficiently closely bonded, but are 100 to 200 ° C., more preferably 110 to 170 ° C. It is preferable to carry out at a press pressure of 1 to 5 MPa. Thereby, the bondability between the polymer electrolyte membrane and the electrode catalyst layer can be enhanced. After performing the hot press, the MEA composed of the electrode catalyst layer and the polymer electrolyte membrane can be obtained by removing the transfer mount.

  When the catalyst layer is formed by the transfer method described above, the gas impermeable layer described above is disposed around the catalyst layer formed on the transfer mount, and an adhesive is applied on the gas impermeable layer. Thus, the gasket layer may be disposed on the transfer mount simultaneously with the catalyst layer. According to such a form, the gasket layer can be transferred to the polymer electrolyte membrane simultaneously with the transfer of the catalyst layer. The press at the time of transfer can also serve as an adhesion step in the production method of the present invention, and the gasket layer and the catalyst layer are converted into a polymer electrolyte membrane in a state where the gasket layer and the end of the catalyst layer are in close contact with each other. Can be transcribed.

  The MEA according to the present invention may generally further have a gas diffusion layer, as will be described in detail below. In this case, the gas diffusion layer is obtained by peeling off the transfer mount in the above method. It is preferable that the joined body is further sandwiched between gas diffusion layers to further join each electrode catalyst layer after joining the electrode catalyst layer and the polymer electrolyte membrane. Alternatively, after the electrode catalyst layer is formed on the surface of the gas diffusion layer in advance to produce the electrode catalyst layer-gas diffusion layer assembly, the electrode catalyst layer-gas diffusion layer assembly is used in the same manner as described above. It is also preferable to sandwich and bond the molecular electrolyte membrane by hot pressing.

  At this time, the gas diffusion layer used in the MEA is not particularly limited, and a known one can be used in the same manner. For example, the conductive and porous properties such as carbon woven fabric, paper-like paper body, felt, and non-woven fabric are used. The thing which uses the sheet-like material which has as a base material etc. are mentioned. The thickness of the substrate may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer, but may be about 30 to 500 μm. If the thickness is less than 30 μm, sufficient mechanical strength or the like may not be obtained, and if it exceeds 500 μm, the distance through which gas or water permeates is undesirably increased.

  The method for forming the electrode catalyst layer on the surface of the gas diffusion layer is not particularly limited, and known methods such as a screen printing method, a deposition method, and a spray method can be similarly applied. Moreover, the formation conditions in particular on the gas diffusion layer surface of an electrode catalyst layer are not restrict | limited, The conditions similar to the past can be applied with the above specific formation methods.

  The gas diffusion layer preferably contains a water repellent in the base material for the purpose of further improving water repellency and preventing a flooding phenomenon. Although it does not specifically limit as said water repellent, Fluorine-type, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. Examples thereof include polymer materials, polypropylene, and polyethylene.

  Moreover, in order to improve water repellency more, the said gas diffusion layer may have a carbon particle layer which consists of an aggregate | assembly of the carbon particle containing a water repellent on the said base material.

  The carbon particles are not particularly limited, and may be conventional ones such as carbon black, graphite, and expanded graphite. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferred because of their excellent electron conductivity and large specific surface area. The particle size of the carbon particles is preferably about 10 to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, it becomes possible to improve contact property with a catalyst layer.

  Examples of the water repellent used for the carbon particle layer include the same water repellents as those described above used for the substrate. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.

  In the carbon particle layer, the mixing ratio of the carbon particles to the water repellent may be insufficient to obtain water repellency as expected when there are too many carbon particles. If there are too many water repellents, sufficient electron conductivity may be obtained. There is a risk that it will not be obtained. Considering these, the mixing ratio of the carbon particles and the water repellent in the carbon particle layer is preferably about 90:10 to 40:60 in terms of mass ratio.

  The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer.

  When a water repellent is contained in the gas diffusion layer, a general water repellent treatment method may be used. For example, after immersing the base material used for a gas diffusion layer in the dispersion liquid of a water repellent agent, the method of heat-drying with oven etc. is mentioned.

  When forming a carbon particle layer on a substrate in a gas diffusion layer, the carbon particles, water repellent, etc. are in a solvent such as water, alcohol solvents such as perfluorobenzene, dichloropentafluoropropane, methanol, ethanol, etc. A slurry is prepared by dispersing in a slurry, and the slurry is applied on a substrate and dried, or the slurry is dried and pulverized to form a powder, and this is applied to the gas diffusion layer. Use it. Then, it is preferable to heat-process at about 250-400 degreeC using a muffle furnace or a baking furnace.

  In addition, the manufacturing method of the joined body including the electrode catalyst layer, the electrolyte membrane, and preferably the gas diffusion layer is not limited to the method described above. That is, after applying and drying the catalyst ink on the electrolyte membrane, hot pressing is performed, the electrode catalyst layer is joined to the solid polymer electrolyte membrane, and the obtained joined body is sandwiched between the gas diffusion layers to form an MEA. Method: A catalyst ink may be applied to the gas diffusion layer and dried to form an electrode catalyst layer, which may be joined to the electrolyte membrane by hot pressing, etc. Just do it.

  As described above, the electrolyte membrane-electrode assembly produced by the electrolyte membrane-electrode assembly of the present invention and the method of the present invention can suppress deterioration of the electrolyte components contained in the electrolyte membrane-electrode assembly. Become. In addition, by providing a gasket layer, it is possible to easily determine the area and arrangement of the catalyst layer, and it is not necessary to accurately align each catalyst layer in advance, so industrial mass production is considered. This is highly desirable. Therefore, by using such an electrolyte membrane-electrode assembly, it is possible to provide a highly reliable fuel cell that has a simple manufacturing process and excellent durability.

  The type of the fuel cell is not particularly limited. In the above description, the polymer electrolyte fuel cell has been described as an example. In addition, an alkaline fuel cell, a direct methanol fuel cell, a micro cell, Examples include a fuel cell. Among them, a polymer electrolyte fuel cell is preferable because it is small in size, and can achieve high density and high output. The fuel cell is useful as a stationary power source in addition to a power source for a moving body such as a vehicle in which a mounting space is limited. However, the fuel cell is particularly useful for an automobile application in which system start / stop and output fluctuation frequently occur. It can be particularly preferably used. The MEA of the present invention is particularly effective for the deterioration of the electrolyte membrane in the idle stop (OCV) state. Therefore, the polymer electrolyte fuel cell, the alkaline fuel cell, and the direct methanol in which the deterioration of the electrolyte membrane is a problem. Show significant effect in type fuel cell and micro fuel cell. For this reason, application to a phosphoric acid fuel cell in which such deterioration of the electrolyte membrane is not regarded as a problem is not included.

  The polymer electrolyte fuel cell is useful not only as a stationary power source but also as a power source for a moving body such as an automobile having a limited mounting space. In particular, moving bodies such as automobiles that are susceptible to corrosion of the carbon support due to the high output voltage required after a relatively long shutdown, and deterioration of the polymer electrolyte due to the high output voltage being taken out during operation. It is particularly preferred to be used as a power source.

  The configuration of the fuel cell is not particularly limited, and a conventionally known technique may be used as appropriate. Generally, the fuel cell has a structure in which an MEA is sandwiched between separators.

  The separator can be used without limitation as long as it is conventionally known, such as those made of carbon such as dense carbon graphite and a carbon plate, and those made of metal such as stainless steel. The separator has a function of separating air and fuel gas, and a channel groove for securing the channel may be formed. The thickness and size of the separator, the shape of the flow channel, and the like are not particularly limited, and may be appropriately determined in consideration of the output characteristics of the obtained fuel cell.

  Further, in order to prevent the gas supplied to each catalyst layer from leaking to the outside, a gas seal portion may be further provided at a portion where the catalyst layer is not formed on the gasket layer. Examples of the material constituting the gas seal portion include rubber materials such as fluoro rubber, silicon rubber, ethylene propylene rubber (EPDM), polyisobutylene rubber, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoro. Fluorine polymer materials such as propylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and thermoplastic resins such as polyolefin and polyester. The thickness of the gas seal portion may be 2 mm to 50 μm, preferably about 1 mm to 100 μm.

  Furthermore, a stack in which a plurality of MEAs are stacked via a separator and connected in series may be formed so that the fuel cell can obtain a desired voltage or the like. The shape of the fuel cell is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Example 1
The MEA shown in FIG. 18 was produced as follows.

[Preparation of anode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the anode catalyst layer produced from the screen printing method was 5.2 cm × 5.2 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Preparation of cathode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the cathode catalyst layer produced from the screen printing method was set to 5.1 cm × 5.1 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Production of membrane electrode assembly (MEA)]
Using a fluorine-based electrolyte membrane (7.5 cm × 7.5 cm, film thickness 25 μm) that does not include a reinforcing layer as a solid polymer electrolyte membrane, on the anode catalyst layer formed on the polytetrafluoroethylene sheet, A solid polymer electrolyte membrane was stacked, and a cathode catalyst layer formed on a polytetrafluoroethylene sheet was further stacked. Thereafter, hot pressing was performed at 130 ° C. and 2.0 MPa for 10 minutes, and then the polytetrafluoroethylene sheet was peeled off to obtain a membrane electrode assembly.

In the cathode catalyst layer transferred onto the solid polymer electrolyte membrane, the amount of Pt supported was 0.4 mg per 1 cm ^{2 of the} apparent electrode area, and the electrode area was 26 cm ² . The anode catalyst layer had a Pt loading of 0.4 mg per 1 cm ² apparent electrode area and an electrode area of 27 cm ² .

[Formation of second gasket layer on end of anode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a second gasket layer having a frame shape with a width of 1.05 cm was prepared by punching an opening having a size of 5.1 cm × 5.1 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.1 cm × 5.1 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, Inc., thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.1 cm at the center of the square sheet. An opening having a size of 5.1 cm was punched out to prepare a frame-like hypersheet having a width of 1.05 cm.

  Here, the MEA produced above was set so that the anode catalyst layer (5.2 cm × 5.2 cm) was on top. Next, the square hypersheet (5.1 cm × 5.1 cm) prepared above was set at the center so that the periphery of the end of the anode catalyst layer could be seen uniformly (0.5 mm). In this state, the second gasket layer was disposed so that the adhesive layer faced downward so that the opening of the second gasket layer prepared above was along the outer periphery of the hypersheet. After placing the second gasket layer, the frame-shaped hypersheet prepared above was placed so as to overlap the second gasket layer and along the outer periphery of the hypersheet to produce a CCM-gasket layer-hypersheet. .

[Formation of first gasket layer at the end of the cathode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a first gasket layer having a frame shape of 1.1 cm width was prepared by punching an opening having a size of 5.0 cm × 5.0 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.0 cm × 5.0 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, 1.5 mm thick) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.0 cm at the center of the square sheet. The opening part which is * 5.0cm was punched out, and the 1.1cm width frame-shaped hypersheet was prepared.

  The CCM-gasket layer-hypersheet produced by forming the second gasket layer on the anode catalyst layer is turned over as a unit and set so that the cathode catalyst layer (5.1 cm × 5.1 cm) is on top. did. Next, in the same manner as in the “formation of the second gasket layer on the anode catalyst layer” step, the square hypersheet prepared above so that the periphery of the end portion of the cathode catalyst layer can be seen uniformly (0.5 mm). (5.0 cm × 5.0 cm) was set at the center. In this state, the first gasket layer was disposed so that the adhesive layer faced downward so that the opening of the first gasket layer prepared above was along the outer periphery of the hypersheet. After the arrangement of the first gasket layer, the frame-shaped hypersheet prepared above was arranged so as to overlap the first gasket layer and along the outer periphery of the hypersheet. In this way, when the gasket layer and the frame-like hypersheet are arranged on both the anode and cathode sides of the MEA, the square hypersheet arranged on each catalyst layer is removed from this unit, and the remaining unit is replaced with a SUS plate (dimensions: 7.4 cm x 7.4 cm, thickness 1 mm) and is hot-pressed at 130 ° C, 0.4 MPa for 1 minute using a hot press machine, and at the end of the catalyst layer that overlaps the gasket layer The pores of the catalyst layer are sufficiently filled to prevent gas from entering.

Comparative Example 1
The MEA shown in FIG. 19 was produced as follows.

[Preparation of anode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the anode catalyst layer produced from the screen printing method was 5.1 cm × 5.1 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Preparation of cathode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the cathode catalyst layer produced from the screen printing method was 5.0 cm × 5.0 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Production of membrane electrode assembly (MEA)]
Using a fluorine-based electrolyte membrane (7.5 cm × 7.5 cm, film thickness 25 μm) that does not include a reinforcing layer as a solid polymer electrolyte membrane, on the anode catalyst layer formed on the polytetrafluoroethylene sheet, A solid polymer electrolyte membrane was stacked, and a cathode catalyst layer formed on a polytetrafluoroethylene sheet was further stacked. Thereafter, hot pressing was performed at 130 ° C. and 2.0 MPa for 10 minutes, and then the polytetrafluoroethylene sheet was peeled off to obtain a membrane electrode assembly.

In the cathode catalyst layer transferred onto the solid polymer electrolyte membrane, the amount of Pt supported was 0.4 mg per 1 cm ^{2 of the} apparent electrode area, and the electrode area was 25 cm ² . The anode catalyst layer had a Pt loading of 0.4 mg per 1 cm ² apparent electrode area and an electrode area of 26 cm ² .

Comparative Example 2
The MEA shown in FIG. 20 was produced as follows.

[Preparation of anode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the anode catalyst layer produced from the screen printing method was 5.0 cm × 5.0 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Preparation of cathode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the cathode catalyst layer produced from the screen printing method was set to 5.1 cm × 5.1 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Production of membrane electrode assembly (MEA)]
Using a fluorine-based electrolyte membrane (7.5 cm × 7.5 cm, film thickness 25 μm) that does not include a reinforcing layer as a solid polymer electrolyte membrane, on the anode catalyst layer formed on the polytetrafluoroethylene sheet, A solid polymer electrolyte membrane was stacked, and a cathode catalyst layer formed on a polytetrafluoroethylene sheet was further stacked. Thereafter, hot pressing was performed at 130 ° C. and 2.0 MPa for 10 minutes, and then the polytetrafluoroethylene sheet was peeled off to obtain a membrane electrode assembly.

In the cathode catalyst layer transferred onto the solid polymer electrolyte membrane, the amount of Pt supported was 0.4 mg per 1 cm ^{2 of the} apparent electrode area, and the electrode area was 26 cm ² . The anode catalyst layer had a Pt loading of 0.4 mg per 1 cm ² apparent electrode area and an electrode area of 25 cm ² .

Comparative Example 3
The MEA shown in FIG. 21 was produced as follows.

[Preparation of anode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the anode catalyst layer produced from the screen printing method was 5.1 cm × 5.1 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Preparation of cathode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 4 times the amount of purified water to the mass of the product and performing degassing for 5 minutes under reduced pressure, 0.5 times the amount of n-propyl alcohol was added, and then 20 wt% Nafion (registered) that serves as the electrolyte (Trademark) -containing solution (DuPont Co., Ltd., DE520) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry was printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.08 mm) by a screen printing method in an amount corresponding to the desired thickness, and at 60 ° C. for 24 hours. Dried. The size of the cathode catalyst layer produced from the screen printing method was set to 5.2 cm × 5.2 cm. Further, the coating layer on the polytetrafluoroethylene sheet was adjusted so that the amount of Pt was 0.4 mg / cm ² .

[Production of membrane electrode assembly (MEA)]
Using a fluorine-based electrolyte membrane (7.5 cm × 7.5 cm, film thickness 25 μm) that does not include a reinforcing layer as a solid polymer electrolyte membrane, on the anode catalyst layer formed on the polytetrafluoroethylene sheet, A solid polymer electrolyte membrane was stacked, and a cathode catalyst layer formed on a polytetrafluoroethylene sheet was further stacked. Thereafter, hot pressing was performed at 130 ° C. and 2.0 MPa for 10 minutes, and then the polytetrafluoroethylene sheet was peeled off to obtain a membrane electrode assembly.

In the cathode catalyst layer transferred onto the solid polymer electrolyte membrane, the amount of Pt supported was 0.4 mg per 1 cm ^{2 of the} apparent electrode area, and the electrode area was 27 cm ² . The anode catalyst layer had a Pt loading of 0.4 mg per 1 cm ² apparent electrode area and an electrode area of 26 cm ² .

[Formation of second gasket layer on end of anode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a second gasket layer having a frame shape of 1.1 cm width was prepared by punching an opening having a size of 5.0 cm × 5.0 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.0 cm × 5.0 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, 1.5 mm thick) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.0 cm at the center of the square sheet. The opening part which is * 5.0cm was punched out, and the 1.1cm width frame-shaped hypersheet was prepared.

  Here, the MEA produced above was set so that the anode catalyst layer (5.1 cm × 5.1 cm) was on top. Next, the square hypersheet (5.0 cm × 5.0 cm) prepared above was set at the center so that the periphery of the end of the anode catalyst layer could be seen uniformly (0.5 mm). In this state, the second gasket layer was disposed so that the adhesive layer faced downward so that the opening of the second gasket layer prepared above was along the outer periphery of the hypersheet. After placing the second gasket layer, the frame-shaped hypersheet prepared above was placed so as to overlap the second gasket layer and along the outer periphery of the hypersheet to produce a CCM-gasket layer-hypersheet. .

[Formation of first gasket layer at the end of the cathode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, an opening having a size of 5.1 cm × 5.1 cm was punched out to prepare a first gasket layer having a frame shape having a width of 1.05 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.1 cm × 5.1 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, Inc., thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.1 cm at the center of the square sheet. An opening having a size of 5.1 cm was punched out to prepare a frame-like hypersheet having a width of 1.05 cm.

  The CCM-gasket layer-hypersheet produced by forming the second gasket layer on the anode catalyst layer is turned over as a unit and set so that the cathode catalyst layer (5.2 cm × 5.2 cm) is on top. did. Next, in the same manner as in the “formation of the second gasket layer on the anode catalyst layer” step, the square hypersheet prepared above so that the periphery of the end portion of the cathode catalyst layer can be seen uniformly (0.5 mm). (5.1 cm × 5.1 cm) was set at the center. In this state, the first gasket layer was disposed so that the adhesive layer faced downward so that the opening of the first gasket layer prepared above was along the outer periphery of the hypersheet. After the arrangement of the first gasket layer, the frame-shaped hypersheet prepared above was arranged so as to overlap the first gasket layer and along the outer periphery of the hypersheet. In this way, when the gasket layer and the frame-like hypersheet are arranged on both the anode and cathode sides of the MEA, the square hypersheet arranged on each catalyst layer is removed from this unit, and the remaining unit is replaced with a SUS plate (dimensions: 7.4 cm × 7.4 cm, thickness 1 mm), and thermocompression bonded at 130 ° C., 0.4 MPa for 1 minute using a hot press machine.

Comparative Example 4
The MEA shown in FIG. 22 was produced as follows.

  First, in the same manner as in the method described in Comparative Example 1, an anode catalyst layer and a cathode catalyst layer were produced, and then a membrane electrode assembly (MEA) was produced.

[Formation of second gasket layer on end of anode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a second gasket layer having a frame shape having a width of 1.0 cm was prepared by punching an opening having a size of 5.2 cm × 5.2 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.2 cm × 5.2 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.2 cm in the center of the square sheet. The opening part which is x5.2 cm was punched out, and a 1.0 cm wide frame-shaped hypersheet was prepared.

  Here, the MEA produced above was set so that the anode catalyst layer (5.1 cm × 5.1 cm) was on top. Next, the square hypersheet (5.2 cm × 5.2 cm) prepared above was set at the center so as to protrude evenly (0.5 mm) from the periphery of the end of the anode catalyst layer. In this state, the second gasket layer was disposed so that the adhesive layer faced downward so that the opening of the second gasket layer prepared above was along the outer periphery of the hypersheet. After the arrangement of the second gasket layer, the frame-shaped hypersheet prepared above was arranged so as to overlap the second gasket layer and along the outer periphery of the hypersheet.

[Formation of first gasket layer at the end of the cathode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, an opening having a size of 5.1 cm × 5.1 cm was punched out to prepare a first gasket layer having a frame shape having a width of 1.05 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.1 cm × 5.1 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, Inc., thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.1 cm at the center of the square sheet. An opening having a size of 5.1 cm was punched out to prepare a frame-like hypersheet having a width of 1.05 cm.

  The CCM-gasket layer-hyper sheet produced by forming the second gasket layer on the anode catalyst layer is turned over as a unit and set so that the cathode catalyst layer (5.0 cm × 5.0 cm) is on top. did. Next, in the same manner as in the “formation of the second gasket layer on the anode catalyst layer” step, the square hypersheet prepared above so as to protrude evenly (0.5 mm) from the periphery of the end portion of the cathode catalyst layer. (5.1 cm × 5.1 cm) was set at the center. In this state, the first gasket layer was disposed so that the adhesive layer faced downward so that the opening of the first gasket layer prepared above was along the outer periphery of the hypersheet. After the arrangement of the first gasket layer, the frame-shaped hypersheet prepared above was arranged so as to overlap the first gasket layer and along the outer periphery of the hypersheet. In this way, when the gasket layer and the frame-like hypersheet are arranged on both the anode and cathode sides of the MEA, the square hypersheet arranged on each catalyst layer is removed from this unit, and the remaining unit is replaced with a SUS plate (dimensions: 7.4 cm × 7.4 cm, thickness 1 mm), and thermocompression bonded at 130 ° C., 0.4 MPa for 1 minute using a hot press machine.

Example 2: OCV durability test About the membrane electrode assembly obtained in Example 1 and Comparative Examples 1-4, each performance was evaluated as follows.

[Evaluation methods]
On both sides of the membrane electrode assembly, carbon paper (size 6.0 cm × 5.5 cm, thickness 200 μm) as a gas diffusion layer and a gas separator with a gas flow path are disposed, and further gold-plated stainless steel The unit cell for evaluation was sandwiched between current collector plates.

Hydrogen gas was supplied as a fuel to the anode side of the evaluation unit cell, and oxygen was supplied as an oxidant to the cathode side. The back pressure was set to atmospheric pressure for both hydrogen and oxygen gas, and the cell temperature was set to 90 ° C. Also, the temperature was set to a temperature of 61.2 ° C. (30% @ 90 ° C.) relative to a hydrogen gas flow rate of 500 cm ³ / min, and a temperature of 61.2 ° C. (relative humidity 30% @ 90 ° C.) of 500 cm ³ / min. . When the unit cell is operated under such conditions, a change in OCV (Open Circuit Voltage) with time is measured, and the result is shown in FIG. In FIG. 23, the horizontal axis represents the endurance time (time), and the vertical axis represents the open circuit voltage (OCV) (V). In addition, it is considered that the point where the OCV suddenly dropped in the figure is the time when a hole is formed in the MEA electrolyte membrane.

  From FIG. 23, in the unit cells having the MEAs of Comparative Example 1 and Comparative Example 2 in which no gasket layer was provided, the OCV dropped sharply in the endurance test time of 28 hours. On the other hand, the unit cell having the MEA of Example 1 in which the gasket layer is provided and the end portion of the catalyst layer is overlapped with the gasket layer and the effective anode catalyst layer is enlarged with respect to the effective cathode catalyst layer, the OCV drops sharply in 96 hours. did. From this, by providing the gasket layer at the end of the catalyst layer, the MEA of the present invention can effectively suppress the decomposition of the electrolyte membrane when holding the OCV, compared with the case where the gasket layer is not provided at the end of the catalyst layer. Indicated. Similarly, the unit cell having the MEA of Comparative Example 3 in which the gasket layer is provided and the end portion of the catalyst layer and the gasket layer are overlapped and the effective cathode catalyst layer is enlarged with respect to the effective anode catalyst layer has an OCV of 60 hours. It plummeted. From this, it is shown that the OCV durability retention can be significantly improved by increasing the effective catalyst layer area on the anode catalyst layer side. Further, the effective anode catalyst layer is made larger than the effective cathode catalyst layer, and when the gasket layer is provided, a gap is provided between the inner end portion on the opening side of the gasket layer and the end portion of the catalyst layer. For unit cells with MEA, OCV plummeted in 37 hours. From this, according to the present invention, when the end of the catalyst layer is not structured so that gas does not enter, simply by increasing the effective catalyst layer area on the anode catalyst layer side, the OCV rapidly drops in a short time, It can be seen that excellent OCV durability retention cannot be achieved.

  In addition to the above results and considerations, after the OCV endurance test, the unit cell is disassembled and one side of the gas separator with the gas flow path is removed, and instead the MEA is fixed by attaching an acrylic plate of a predetermined shape. A visualization leak test was performed by supplying helium gas from the gas separator side and pressurizing (about 10 kPa), and the perforated portion of the electrolyte membrane was observed. As a result, with respect to the MEAs of Comparative Example 1, Comparative Example 2, and Comparative Example 4, a relatively large amount of helium gas bubbles were generated from the vicinity of the end of the catalyst layer, but with respect to the MEAs of Example 1 and Comparative Example 3, It was confirmed that bubbles of helium gas were generated not in the edges but in the entire catalyst layer.

  From the above results, it was confirmed that the MEA of Example 1 has significantly improved OCV durability as compared with other MEAs.

Example 3
The MEA shown in FIG. 24 was produced as follows.

[Preparation of anode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 3 times the amount of purified water and 3 times the amount of propylene glycol with respect to the mass of the product, vacuum defoaming operation for 5 minutes, 0.5 times the amount of n-propyl alcohol was added, and then the electrolyte A solution containing 20 wt% Nafion (registered trademark) (DuPont Co., Ltd., DE2020) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry is printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.2 mm) by a screen printing method in an amount corresponding to a desired thickness, and then at 60 ° C. for 24 hours. Dried. The size of the anode catalyst layer produced from the screen printing method was 5.1 cm × 5.1 cm. The coating layer on the polytetrafluoroethylene sheet was adjusted so that the Pt amount was 0.05 mg / cm ² .

[Preparation of cathode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 3 times the amount of purified water and 3 times the amount of propylene glycol with respect to the mass of the product, vacuum defoaming operation for 5 minutes, 0.5 times the amount of n-propyl alcohol was added, and then the electrolyte A solution containing 20 wt% Nafion (registered trademark) (DuPont Co., Ltd., DE2020) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry is printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.2 mm) by a screen printing method in an amount corresponding to a desired thickness, and then at 60 ° C. for 24 hours. Dried. The size of the cathode catalyst layer produced from the screen printing method was 5.0 cm × 5.0 cm. The coating layer on the polytetrafluoroethylene sheet was adjusted so that the Pt amount was 0.35 mg / cm ² .

[Production of membrane electrode assembly (MEA)]
Using a fluorine-based electrolyte membrane (7.5 cm × 7.5 cm, film thickness 30 μm) having a reinforcing layer as the solid polymer electrolyte membrane, this solid is formed on the anode catalyst layer formed on the polytetrafluoroethylene sheet. A polymer electrolyte membrane was stacked, and a cathode catalyst layer formed on a polytetrafluoroethylene sheet was further stacked. Thereafter, hot pressing was performed at 130 ° C. and 2.0 MPa for 10 minutes, and then the polytetrafluoroethylene sheet was peeled off to obtain a membrane electrode assembly.

In the cathode catalyst layer transferred onto the solid polymer electrolyte membrane, the amount of Pt supported was 0.4 mg per 1 cm ^{2 of the} apparent electrode area, and the electrode area was 25 cm ² . The anode catalyst layer had a Pt loading of 0.4 mg per 1 cm ² apparent electrode area and an electrode area of 26 cm ² .

[Formation of second gasket layer on end of anode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a second gasket layer having a frame shape with a width of 1.05 cm was prepared by punching an opening having a size of 5.1 cm × 5.1 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.1 cm × 5.1 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, Inc., thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.1 cm at the center of the square sheet. An opening having a size of 5.1 cm was punched out to prepare a frame-like hypersheet having a width of 1.05 cm.

  Here, the MEA produced above was set so that the anode catalyst layer (5.1 cm × 5.1 cm) was on top. Next, the square hypersheet (5.1 cm × 5.1 cm) prepared above was set at the center so as to overlap the periphery of the end of the anode catalyst layer. In this state, the second gasket layer was disposed so that the adhesive layer faced downward so that the opening of the second gasket layer prepared above was along the outer periphery of the hypersheet. After placing the second gasket layer, the frame-shaped hypersheet prepared above was placed so as to overlap the second gasket layer and along the outer periphery of the hypersheet to produce a CCM-gasket layer-hypersheet. .

[Formation of first gasket layer at the end of the cathode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a first gasket layer having a frame shape of 1.1 cm width was prepared by punching an opening having a size of 5.0 cm × 5.0 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.0 cm × 5.0 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, 1.5 mm thick) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.0 cm at the center of the square sheet. The opening part which is * 5.0cm was punched out, and the 1.1cm width frame-shaped hypersheet was prepared.

  The CCM-gasket layer-hyper sheet produced by forming the second gasket layer on the anode catalyst layer is turned over as a unit and set so that the cathode catalyst layer (5.0 cm × 5.0 cm) is on top. did. Next, in the same manner as in the “formation of the second gasket layer on the anode catalyst layer” step, the square hypersheet (5.0 cm × 5 .5) prepared above so as to overlap with the periphery of the end of the cathode catalyst layer. 0 cm) was set at the center. In this state, the first gasket layer was disposed so that the adhesive layer faced downward so that the opening of the first gasket layer prepared above was along the outer periphery of the hypersheet. After the arrangement of the first gasket layer, the frame-shaped hypersheet prepared above was arranged so as to overlap the first gasket layer and along the outer periphery of the hypersheet. In this way, when the gasket layer and the frame-like hypersheet are arranged on both the anode and cathode sides of the MEA, the square hypersheet arranged on each catalyst layer is removed from this unit, and the remaining unit is replaced with a SUS plate (dimensions: 7.4 cm × 7.4 cm, thickness 1 mm), and is hot-pressed at 130 ° C., 0.4 MPa for 1 minute using a hot press machine, and at the end of the catalyst layer in contact with the gasket layer The gasket layer end and the catalyst layer end are in close contact with each other so that gas does not enter.

Example 4
The MEA shown in FIG. 25 was produced as follows.

[Preparation of anode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 3 times the amount of purified water and 3 times the amount of propylene glycol with respect to the mass of the product, vacuum defoaming operation for 5 minutes, 0.5 times the amount of n-propyl alcohol was added, and then the electrolyte A solution containing 20 wt% Nafion (registered trademark) (DuPont Co., Ltd., DE2020) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry is printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.2 mm) by a screen printing method in an amount corresponding to a desired thickness, and then at 60 ° C. for 24 hours. Dried. The size of the anode catalyst layer produced from the screen printing method was 5.2 cm × 5.2 cm. The coating layer on the polytetrafluoroethylene sheet was adjusted so that the Pt amount was 0.05 mg / cm ² .

[Preparation of cathode catalyst layer]
Carbon support on which Pt particles are supported using a carbon support (Ketjen Black EC, manufactured by Ketjen Black International Co., Ltd., BET surface area = 800 m ² / g) on which Pt particles are supported at a Pt support concentration of 50% by mass. After adding 3 times the amount of purified water and 3 times the amount of propylene glycol with respect to the mass of the product, vacuum defoaming operation for 5 minutes, 0.5 times the amount of n-propyl alcohol was added, and then the electrolyte A solution containing 20 wt% Nafion (registered trademark) (DuPont Co., Ltd., DE2020) was added. The electrolyte in the solution used was a solid content mass ratio (Carbon (carbon) / Ionomer (electrolyte)) of 1.0 / 0.9 with respect to the mass of the carbon support.

The obtained mixed slurry was dispersed by an ultrasonic homogenizer, and vacuum degassing was performed to prepare a catalyst slurry. The produced catalyst slurry is printed on one side of a polytetrafluoroethylene sheet (7.5 cm × 7.5 cm, thickness 0.2 mm) by a screen printing method in an amount corresponding to a desired thickness, and then at 60 ° C. for 24 hours. Dried. The size of the cathode catalyst layer produced from the screen printing method was set to 5.1 cm × 5.1 cm. The coating layer on the polytetrafluoroethylene sheet was adjusted so that the Pt amount was 0.35 mg / cm ² .

[Production of membrane electrode assembly (MEA)]
Using a fluorine-based electrolyte membrane (7.5 cm × 7.5 cm, film thickness 30 μm) having a reinforcing layer as the solid polymer electrolyte membrane, this solid is formed on the anode catalyst layer formed on the polytetrafluoroethylene sheet. A polymer electrolyte membrane was stacked, and a cathode catalyst layer formed on a polytetrafluoroethylene sheet was further stacked. Thereafter, hot pressing was performed at 130 ° C. and 2.0 MPa for 10 minutes, and then the polytetrafluoroethylene sheet was peeled off to obtain a membrane electrode assembly.

In the cathode catalyst layer transferred onto the solid polymer electrolyte membrane, the amount of Pt supported was 0.4 mg per 1 cm ^{2 of the} apparent electrode area, and the electrode area was 25 cm ² . The anode catalyst layer had a Pt loading of 0.4 mg per 1 cm ² apparent electrode area and an electrode area of 26 cm ² .

[Formation of second gasket layer on end of anode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a second gasket layer having a frame shape with a width of 1.05 cm was prepared by punching an opening having a size of 5.1 cm × 5.1 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.1 cm × 5.1 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, Inc., thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.1 cm at the center of the square sheet. An opening having a size of 5.1 cm was punched out to prepare a frame-like hypersheet having a width of 1.05 cm.

  Here, the MEA produced above was set so that the anode catalyst layer (5.2 cm × 5.2 cm) was on top. Next, the square hypersheet (5.1 cm × 5.1 cm) prepared above was set at the center so that the periphery of the end of the anode catalyst layer could be seen uniformly (0.5 mm). In this state, the second gasket layer was disposed so that the adhesive layer faced downward so that the opening of the second gasket layer prepared above was along the outer periphery of the hypersheet. After placing the second gasket layer, the frame-shaped hypersheet prepared above was placed so as to overlap the second gasket layer and along the outer periphery of the hypersheet to produce a CCM-gasket layer-hypersheet. .

[Formation of first gasket layer at the end of the cathode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a first gasket layer having a frame shape of 1.1 cm width was prepared by punching an opening having a size of 5.0 cm × 5.0 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.0 cm × 5.0 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, 1.5 mm thick) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.0 cm at the center of the square sheet. The opening part which is * 5.0cm was punched out, and the 1.1cm width frame-shaped hypersheet was prepared.

  The CCM-gasket layer-hypersheet produced by forming the second gasket layer on the anode catalyst layer is turned over as a unit and set so that the cathode catalyst layer (5.1 cm × 5.1 cm) is on top. did. Next, in the same manner as in the “formation of the second gasket layer on the anode catalyst layer” step, the square hypersheet prepared above so that the periphery of the end portion of the cathode catalyst layer can be seen uniformly (0.5 mm). (5.0 cm × 5.0 cm) was set at the center. In this state, the first gasket layer was disposed so that the adhesive layer faced downward so that the opening of the first gasket layer prepared above was along the outer periphery of the hypersheet. After the arrangement of the first gasket layer, the frame-shaped hypersheet prepared above was arranged so as to overlap the first gasket layer and along the outer periphery of the hypersheet. In this way, when the gasket layer and the frame-like hypersheet are arranged on both the anode and cathode sides of the MEA, the square hypersheet arranged on each catalyst layer is removed from this unit, and the remaining unit is replaced with a SUS plate (dimensions: 7.4 cm x 7.4 cm, thickness 1 mm) and is hot-pressed at 130 ° C, 0.4 MPa for 1 minute using a hot press machine, and at the end of the catalyst layer that overlaps the gasket layer The pores of the catalyst layer are sufficiently filled to prevent gas from entering.

Example 5: OCV Durability Test For the membrane / electrode assembly obtained in Examples 3 and 4, an evaluation unit cell was prepared according to the same method as in Example 2, and the performance of the unit cell was evaluated. The result is shown in FIG.

  Comparing the results of FIG. 23 and FIG. 26, the unit cell having the MEA obtained in Examples 3 and 4 is the same as the unit cell having the MEA obtained in Example 1 and the MEA obtained in Comparative Examples 1 to 4. The OCV retention time is longer than that of the unit cell having the. In Examples 3 and 4, since the electrolyte membrane having the reinforcing layer is used, it is considered that the reinforcing layer effectively suppresses and prevents the formation of holes in the electrolyte membrane. In addition, as shown in FIG. 27, when the gasket layer is provided, Example 3 has a structure in which a gap or an overlap portion is not provided between the inner end portion of the gasket layer and the end portion of the catalyst layer. Unit cells with the MEA began to become unstable in OCV in about 395 hours (ie, perforated). On the other hand, as shown in FIG. 28, when the gasket layer was provided, the unit cell having the MEA of Example 4 arranged so that the inner end of the gasket layer overlapped the end of the catalyst layer was approximately 480 hours. OCV plummeted. From these results, it is shown that the OCV holding time can be significantly extended by the presence of an overlapping portion with the inner end portion of the gasket layer at the end portion of the catalyst layer.

  From the above results, it was confirmed that the MEAs of Examples 3 and 4 can further significantly improve the OCV durability.

Example 6
In the same manner as in Example 4, anode and cathode catalyst layers were produced, and a membrane electrode assembly (MEA) was further produced.

[Formation of second gasket layer on end of anode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a second gasket layer having a frame shape with a width of 1.05 cm was prepared by punching an opening having a size of 5.1 cm × 5.1 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.1 cm × 5.1 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.2 cm in the center of the square sheet. The opening part which is x5.2 cm was punched out, and a 1.0 cm wide frame-shaped hypersheet was prepared.

  Here, the MEA produced above was set so that the anode catalyst layer (5.2 cm × 5.2 cm) was on top. Next, the square hypersheet (5.1 cm × 5.1 cm) prepared above was set at the center so that the periphery of the end of the anode catalyst layer could be seen uniformly (0.5 mm). In this state, the second gasket layer was disposed so that the adhesive layer faced downward so that the opening of the second gasket layer prepared above was along the outer periphery of the hypersheet. After placing the second gasket layer, place the frame-shaped hypersheet prepared above so that it overlaps the second gasket layer, and evenly (0.5 mm) on the outer periphery of the square hypersheet did.

[Formation of first gasket layer at the end of the cathode catalyst layer]
After punching out a PEN film with urethane-based hot-melt adhesive layer (manufactured by Teijin DuPont, PEN thickness 25 μm, adhesive layer 25 μm) so that the outer dimensions are 7.2 cm × 7.2 cm, the center of this square film Then, a first gasket layer having a frame shape of 1.1 cm width was prepared by punching an opening having a size of 5.0 cm × 5.0 cm. Subsequently, a hyper sheet (manufactured by Japan Gore-Tex Co., Ltd., thickness 1.5 mm) was punched out so that the outer dimensions were 5.0 cm × 5.0 cm, and a square hyper sheet was prepared. Further, after punching out a hyper sheet (Japan Gore-Tex, Inc., thickness 1.5 mm) so that the outer dimensions are 7.2 cm × 7.2 cm, the dimension is 5.1 cm at the center of the square sheet. An opening having a size of 5.1 cm was punched out to prepare a frame-like hypersheet having a width of 1.05 cm.

  The CCM-gasket layer-hypersheet produced by forming the second gasket layer on the anode catalyst layer is turned over as a unit and set so that the cathode catalyst layer (5.1 cm × 5.1 cm) is on top. did. Next, in the same manner as in the “formation of the second gasket layer on the anode catalyst layer” step, the square hypersheet prepared above so that the periphery of the end portion of the cathode catalyst layer can be seen uniformly (0.5 mm). (5.0 cm × 5.0 cm) was set at the center. In this state, the first gasket layer was disposed so that the adhesive layer faced downward so that the opening of the first gasket layer prepared above was along the outer periphery of the hypersheet. After arranging the first gasket layer, the frame-shaped hypersheet prepared above is overlaid on the first gasket layer, and the outer periphery of the square hypersheet is evenly spaced (0.5 mm). Arranged. In this way, when the gasket layer and the frame-like hypersheet are arranged on both the anode and cathode sides of the MEA, the square hypersheet arranged on each catalyst layer is removed from this unit, and the remaining unit is replaced with a SUS plate (dimensions: 7.4 cm × 7.4 cm, thickness 1 mm), and thermocompression bonded at 130 ° C., 0.4 MPa for 1 minute using a hot press machine. In this process, no pressure is applied to the region where the catalyst layer end and the gasket layer overlap during thermocompression bonding, so the catalyst layer end overlapping the gasket layer has a structure in which the adhesive does not completely enter the pores and gas enters. The structure was such that the pores of the catalyst layer were not completely filled, leaving room for it.

Example 7: OCV Durability Test For the membrane / electrode assembly obtained in Examples 4 and 6, an evaluation unit cell was prepared according to the same method as in Example 2, and the performance of the unit cell was evaluated. The result is shown in FIG.

  Comparing the results of FIG. 23 and FIG. 29, the unit cell having the MEA obtained in Examples 4 and 6 is the unit cell having the MEA obtained in Example 1 and the MEA obtained in Comparative Examples 1 to 4. The OCV retention time is longer than that of the unit cell having the. In Examples 4 and 6, since the one in which the reinforcing layer is arranged in the electrolyte membrane is used, it is considered that the reinforcing layer effectively suppresses / prevents the formation of pores in the electrolyte membrane. Is done. 29, as shown in FIG. 30, when the gasket layer is provided, the gasket layer is disposed so that the inner end portion of the gasket layer overlaps the end portion of the catalyst layer, and the pores of the catalyst layer in the overlapping region are bonded. In the unit cell having the MEA of Example 4 having a structure sufficiently filled with the agent, the OCV dropped sharply in about 480 hours. On the other hand, as shown in FIG. 31, the unit cell having the MEA of Example 6 having a structure in which the pores of the catalyst layer in the overlapping region are not completely filled with the adhesive is approximately 400 hours. OCV plummeted in a short time compared to the one. From the above results, it is preferable in terms of OCV retention that the pores of the catalyst layer in the overlapping portion between the inner end portion of the gasket layer and the end portion of the catalyst layer are sufficiently filled with the adhesive of the adhesive layer. Indicated.

  From the above results, it was confirmed that the MEAs of Examples 4 and 6 can further significantly improve the OCV durability.

  In addition to the above test, after the OCV endurance test, the film thickness of the region where the inner end portion of the first gasket layer on the cathode catalyst layer side and the end portion of the cathode catalyst layer overlap (regions with different degrees of impregnation of the adhesive) ( “X” in FIGS. 30 and 31) was measured, and the results are shown in Table 1 below. In Table 1 below, the initial product is the film thickness of the corresponding region before the OCV durability test.

From Table 1 above, in the region where the end of the cathode catalyst layer and the inner end of the gasket layer overlap, the MEA of Example 4 in which the cathode catalyst layer in this region was intentionally impregnated with the adhesive of the adhesive layer; When the film thickness after the durability test (“X” in FIGS. 31 and 32, respectively) was compared with the MEA of Example 6 that was not intentionally impregnated, the OCV retention (durability) time of Example 4 was longer. The film thickness was 22 μm, which was thicker than that of Example 6. This is because in the MEA of Example 6, gas (oxygen) reaches the catalyst layer in the region, so that hydrogen peroxide (H ₂ O ₂ ) is generated in the anode catalyst layer in the region, and the membrane Deterioration occurs, and thinning proceeds. On the other hand, in the MEA of Example 4, the region penetrates the adhesive and is impermeable to gas. Therefore, gas (oxygen) does not reach the region, so that the reaction of generating H ₂ O ₂ occurs. It is considered that the area of thinning can be mitigated.

  The electrolyte membrane-electrode assembly (MEA) of the present invention can be applied to a fuel cell having excellent durability and good fuel efficiency.

It is explanatory drawing which shows the gas atmosphere of the anode / cathode after leaving it for a long time, and the gas atmosphere and local battery state of the anode / cathode at the time of starting after leaving for a long time. It is explanatory drawing which shows the cross leak of oxygen at the time of OCV holding | maintenance. It is a figure explaining the inhibitory effect of the oxygen cross leak at the time of OCV holding | maintenance by this invention. It is a figure explaining the inhibitory effect of the oxygen cross leak at the time of OCV holding | maintenance by this invention. It is a figure which shows the structure of MEA by the 1st embodiment of this invention. It is a figure which shows the structure of MEA by the 2nd embodiment of this invention. It is a figure which shows the structure of MEA by the 3rd embodiment of this invention. It is a figure which shows the structure of MEA by the 4th embodiment of this invention. It is a figure which shows the structure of MEA by the 5th embodiment of this invention. It is a figure which shows the structure of MEA by the 6th embodiment of this invention. It is a figure which shows the structure of MEA by the 7th embodiment of this invention. It is a figure which shows a mode that MEA by the 1st embodiment in the 5th aspect of this invention is manufactured. It is a figure which shows a mode that MEA by the 2nd embodiment in the 5th aspect of this invention is manufactured. It is a figure which shows a mode that MEA by the 3rd embodiment in the 5th aspect of this invention is manufactured. It is a figure which shows a mode that MEA by the 4th embodiment in the 5th aspect of this invention is manufactured. It is a figure which shows a mode that MEA by the 5th embodiment in the 5th aspect of this invention is manufactured. It is a figure which shows MEA manufactured by the manufacturing method shown in FIG. 14 or FIG. It is a figure which shows a mode that MEA by the 6th embodiment of this invention is manufactured. 1 is a diagram illustrating a structure of an MEA of Example 1. FIG. FIG. 4 is a diagram showing a structure of an MEA of Comparative Example 1. 6 is a view showing a structure of an MEA of Comparative Example 2. FIG. 6 is a view showing a structure of an MEA of Comparative Example 3. FIG. 6 is a view showing a structure of an MEA of Comparative Example 4. FIG. The OCV durability test result in Example 2 is shown. FIG. 4 is a diagram showing a structure of an MEA of Example 3. FIG. 6 is a diagram showing the structure of an MEA of Example 4. The OCV durability test result in Example 5 is shown. It is a figure which shows the edge part cross-section of MEA of Example 3. FIG. It is a figure which shows the edge part cross-section of MEA of Example 4. FIG. The OCV durability test result in Example 7 is shown. It is a figure which shows the edge part cross-section of MEA of Example 4. FIG. It is a figure which shows the edge part cross-section of MEA of Example 6. FIG. It is a figure which shows arrangement | positioning of the effective cathode catalyst layer, effective anode catalyst layer, cathode catalyst layer, and anode catalyst layer in MEA of this invention. It is a figure explaining the suppression / prevention effect of a crack at the time of including propylene glycol in the catalyst layer of MEA of the present invention.

Claims (33)

A polymer electrolyte membrane;
A cathode catalyst layer disposed on one side of the polymer electrolyte membrane;
An anode catalyst layer disposed on the other side of the polymer electrolyte membrane;
A first gasket layer formed at an end of the cathode catalyst layer such that an area of the effective anode catalyst layer is larger than an area of the effective cathode catalyst layer;
An electrolyte membrane-electrode assembly comprising:   2. The electrolyte membrane-electrode assembly according to claim 1, wherein an end of the first gasket layer is inserted between the cathode catalyst layer and the polymer electrolyte membrane or covers the end of the cathode catalyst layer.   The electrolyte membrane-electrode assembly according to claim 1 or 2, wherein the second gasket layer is further formed on at least a part of an end portion or a peripheral portion of the anode catalyst layer.   (1) The first gasket layer is formed between the cathode catalyst layer and the polymer electrolyte membrane so that the first gasket layer is covered with the end portion of the cathode catalyst layer, and the second gasket layer is formed at the end portion of the anode catalyst layer. Formed between the anode catalyst layer and the polymer electrolyte membrane to be coated; (2) a first gasket layer is formed to cover the end of the cathode catalyst layer, and a second gasket layer; Or (3) between the cathode catalyst layer and the polymer electrolyte membrane so that the first gasket layer is coated at the end of the cathode catalyst layer. The electrolyte membrane-electrode assembly according to claim 3, wherein the electrolyte membrane-electrode assembly is formed and formed so that the second gasket layer covers an end portion of the anode catalyst layer.   The electrolyte membrane according to any one of claims 1 to 4, wherein an end portion of the cathode catalyst layer and an end portion of the anode catalyst layer terminate at substantially the same position with respect to the thickness direction of the electrolyte membrane-electrode assembly. An electrode assembly.   5. The electrolyte membrane-electrode according to claim 1, wherein the end of the anode catalyst layer terminates beyond the end of the cathode catalyst layer with respect to the thickness direction of the electrolyte membrane-electrode assembly. Joined body.   The electrolyte membrane-electrode assembly according to any one of claims 1 to 6, wherein the first gasket layer is formed by forming a first adhesive layer on a first gas-impermeable layer.   The electrolyte membrane-electrode assembly according to claim 7, wherein the material constituting the first adhesive layer is a hot-melt adhesive.   The inner end portion of the first gas impermeable layer is located outside the end portion of the cathode catalyst layer with respect to the thickness direction of the electrolyte membrane-electrode assembly, and the inner end portion of the gas impermeable layer and the cathode The electrolyte membrane-electrode assembly according to claim 7 or 8, wherein the first adhesive layer is disposed between the ends of the catalyst layer.   The electrolyte membrane-electrode assembly according to any one of claims 3 to 9, wherein the second gasket layer is formed by forming a second adhesive layer on the second gas impermeable layer.   The electrolyte membrane-electrode assembly according to claim 10, wherein the material constituting the second adhesive layer is a hot-melt adhesive.   The inner end of the second gas impermeable layer is located outside the end of the anode catalyst layer with respect to the thickness direction of the electrolyte membrane-electrode assembly, and the inner end of the gas impermeable layer, The electrolyte membrane-electrode assembly according to claim 10 or 11, wherein the second adhesive layer is disposed between an end portion of the anode catalyst layer.   The second gasket layer is further formed at the end of the anode catalyst layer. At this time, the length [A (mm)] of the overlapping portion between the end of the cathode catalyst layer and the first gasket layer is more than 0. (A> 0), the length [B (mm)] of the overlapping portion between the end of the anode catalyst layer and the second gasket layer is more than 0 and 2 mm or less (0 <B ≦ 2), and the electrolyte The distance [C (mm)] between the outer end portion of the cathode catalyst layer and the outer end portion of the anode catalyst layer that ends beyond the outer end portion of the cathode catalyst layer with respect to the thickness direction of the membrane-electrode assembly is The electrolyte membrane-electrode assembly according to any one of claims 1 to 12, which is larger than B (B <C).   The distance [X (mm)] between the outer end portion of the cathode catalyst layer and the inner end portion of the second gasket layer with respect to the thickness direction of the electrolyte membrane-electrode assembly is more than 0 (X> 0). The electrolyte membrane-electrode assembly according to claim 13.   The part which overlaps with the edge part of a cathode catalyst layer in the 1st gasket layer, or the part which contact | connects the edge part of a cathode catalyst layer has a function which suppresses gas permeability at least. The electrolyte membrane-electrode assembly according to the description.   The part which overlaps with the edge part of an anode catalyst layer in the 2nd gasket layer, or the part which contact | connects the edge part of an anode catalyst layer has a function which suppresses gas permeability at least, Any one of Claims 3-15 The electrolyte membrane-electrode assembly according to the description. Forming a first gasket layer on the cathode catalyst layer side surface of the polymer electrolyte membrane, and further forming a cathode catalyst layer so that an end of the gasket layer and an end of the cathode catalyst layer overlap; And forming a second gasket layer on the anode catalyst layer side surface of the polymer electrolyte membrane, and further forming an anode catalyst layer so that the end of the gasket layer and the end of the anode catalyst layer overlap each other And the first gasket layer and the second gasket layer are formed such that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer. Body manufacturing method. Forming a cathode catalyst layer on the cathode catalyst layer side surface of the polymer electrolyte membrane, and further forming a first gasket layer so as to cover an end of the cathode catalyst layer; and an anode of the polymer electrolyte membrane Forming an anode catalyst layer on the surface of the catalyst layer, and further forming a second gasket layer so as to cover an end of the anode catalyst layer, and the first gasket layer and the second gasket layer The method for producing an electrolyte membrane-electrode assembly, wherein the gasket layer is formed so that an area of the effective anode catalyst layer is larger than an area of the effective cathode catalyst layer. Forming a first gasket layer on the cathode catalyst layer side surface of the polymer electrolyte membrane, and further forming a cathode catalyst layer so that an end of the gasket layer and an end of the cathode catalyst layer overlap; And a step of forming an anode catalyst layer on the anode catalyst layer side surface of the polymer electrolyte membrane, and further forming a second gasket layer so as to cover an end of the anode catalyst layer, and The method for producing an electrolyte membrane-electrode assembly is characterized in that the gasket layer and the second gasket layer are formed such that the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer.   The cathode catalyst layer and the anode catalyst layer are formed such that an end portion of the cathode catalyst layer and an end portion of the anode catalyst layer are terminated at substantially the same position in the thickness direction of the electrolyte membrane-electrode assembly. The method of any one of 17-19.   The cathode catalyst layer and the anode catalyst layer are formed so that an end portion of the anode catalyst layer is terminated beyond an end portion of the cathode catalyst layer with respect to a thickness direction of the electrolyte membrane-electrode assembly. 20. The method according to any one of items 19. A catalyst layer forming step of forming the cathode catalyst layer and the anode catalyst layer on each surface of the polymer electrolyte membrane so that the area of the anode catalyst layer is larger than the area of the cathode catalyst layer;
A first gasket layer in which a first adhesive layer is formed on a first gas impermeable layer is formed on the polymer electrolyte membrane so that the first adhesive layer and the polymer electrolyte membrane face each other. A second gasket layer disposed on at least a part of the peripheral edge and having a second gas-impermeable layer and a second adhesive layer formed thereon, the second adhesive layer and the polymer electrolyte membrane; A gasket layer disposing step of disposing at least a part of an end portion or a peripheral portion of the polymer electrolyte membrane so as to face each other;
An adhesion step of bonding the first gasket layer and the second gasket layer to the polymer electrolyte membrane by pressing the laminate obtained by the catalyst layer forming step and the gasket layer arranging step;
A method for producing an electrolyte membrane-electrode assembly, comprising:   The manufacturing method according to claim 22, wherein a material constituting the adhesive layer is a hot-melt adhesive, and a press in the bonding step is a hot press.   A guide for arranging a guide member for aligning the arrangement position of the first gasket layer or the second gasket layer on at least one surface of the cathode catalyst layer or the anode catalyst layer after the catalyst layer forming step. The manufacturing method according to claim 23, further comprising a member arranging step, wherein the gasket layer arranging step is performed after the guide member arranging step.   In the gasket layer disposing step, at least one of an end portion of the first gasket layer and an end portion of the cathode catalyst layer, or an end portion of the second gasket layer and an end portion of the anode catalyst layer substantially matches. The manufacturing method of any one of Claims 22-24 performed as follows.   The adhesive layer of at least one of said 1st gasket layer or said 2nd gasket layer has a thin part with a thin part compared with another part in any one of Claims 22-25. The production method according to item.   27. The manufacturing method according to any one of claims 22 to 26, wherein at least one of the first gasket layer or the second gasket layer has an exposed portion where no adhesive layer is present.   The gasket layer disposing step is performed between an end portion of the first gasket layer and an end portion of the cathode catalyst layer, or between an end portion of the second gasket layer and an end portion of the anode catalyst layer. The production method according to any one of claims 22 to 27, wherein the production is performed so that at least one of the gaps exists.   The manufacturing method according to claim 28, wherein the bonding step is performed so as to be filled with the adhesive layer moved to the gap by a press in the bonding step.   30. In the adhesive layer of at least one of the first gasket layer or the second gasket layer, the thickness of a part of the adhesive layer is thicker than the other part. Manufacturing method.   The manufacturing method according to claim 30, wherein a part of the adhesive layer is an inner end portion of the adhesive layer.   In at least one of the first gasket layer and the second gasket layer, a plurality of the hot-melt adhesive layers are convexly formed in a direction from the outer end portion to the inner end portion of the gasket layer. The manufacturing method according to any one of claims 23 to 31, wherein the plurality of hot-melt adhesive layers are melted and integrated in the bonding step.   A fuel cell using the electrolyte membrane-electrode assembly according to any one of claims 1 to 16 or the electrolyte membrane-electrode assembly produced by the method according to any one of claims 17 to 32.

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