JP5458774B2 - Electrolyte membrane-electrode assembly - Google Patents

Description

  The present invention relates to an electrolyte membrane-electrode assembly (MEA), and more particularly to an electrolyte membrane-electrode assembly for a fuel cell. In particular, the present invention relates to an electrolyte membrane-electrode assembly excellent in durability and power generation performance, and particularly to an electrolyte membrane-electrode assembly for a fuel cell.

  Conventionally, polymer electrolytes constituting a catalyst layer and an electrolyte membrane of a fuel cell are roughly classified into a fluorine-based electrolyte and a hydrocarbon-based electrolyte. Among these, the fluorine-based electrolyte is excellent in heat resistance and chemical stability because it has a C—F bond, and in particular, perfluoro known under the trade name of Nafion (registered trademark, manufactured by DuPont). A fluorine-based electrolyte typified by sulfonic acid is used. However, the fluorine-based electrolyte has drawbacks that it is difficult to manufacture and is very expensive. For this reason, it is considered to use a hydrocarbon electrolyte instead of the fluorine electrolyte. This hydrocarbon-based electrolyte has an advantage that the raw material is inexpensive, the manufacturing process is simple, and the selectivity of the material is high as compared with the above-mentioned fluorine-based electrolyte. However, the hydrocarbon-based electrolyte layer has low proton conductivity, which causes a decrease in power generation performance. For this reason, it was insufficient to use a hydrocarbon-based electrolyte in the catalyst layer.

  For this reason, conventionally, it has also been proposed to use a fluorine-based electrolyte for the catalyst layer and a hydrocarbon-based electrolyte for the electrolyte membrane. However, when the catalyst layer and the electrolyte membrane are made of different materials in this way, the adhesion is insufficient, peeling occurs at these interfaces, the electrical resistance at the interfaces increases, and the reliability of the battery performance Bring about a decline.

  In order to solve the above problem, it has been proposed to provide an adhesive layer between the catalyst layer and the electrolyte membrane (for example, Patent Document 1). Patent Document 1 is characterized in that an adhesive layer containing a hydrocarbon electrolyte is provided between a catalyst electrode containing a fluorine electrolyte and an electrolyte membrane made of a hydrocarbon electrolyte. According to Patent Literature 1, adhesion at the interface between the catalyst layer and the electrolyte membrane can be improved. In direct methanol fuel cells, although the fluorine-based (especially perfluorosulfonic acid) electrolyte layer has low methanol permeation-blocking capability, the hydrocarbon-based electrolyte layer has excellent methanol blocking performance. Can be suppressed.

JP 2007-26708 A

  However, in Patent Document 1, although elution of catalyst ions can be prevented, since the hydrocarbon polymer electrolyte in the catalyst layer has low material transport performance, the fuel cell of Patent Document 1 is particularly suitable for power generation in a high current density region. Performance is inferior, and durability and power generation performance cannot be compatible.

  The present inventors have intensively studied to solve the above problems. As a result, the catalyst layer has a laminated structure of a layer using a fluorine-based electrolyte and a layer using a hydrocarbon-based electrolyte, and the hydrocarbon-based electrolyte layer is disposed on the electrolyte membrane side, so that the catalyst is eluted into the electrolyte membrane. It was learned that it can be suppressed / prevented. Based on the above findings, the present invention has been completed.

  That is, the above object is achieved by an electrolyte membrane-electrode assembly comprising a fluorine-based electrolyte-containing catalyst layer and a hydrocarbon-based electrolyte-containing catalyst layer, and having the hydrocarbon-based electrolyte-containing catalyst layer disposed on the electrolyte membrane side.

  According to the present invention, elution of the catalyst to the electrolyte membrane can be suppressed / prevented. Therefore, the electrolyte membrane-electrode assembly of the present invention is excellent in durability and power generation performance.

1 is a schematic cross-sectional view schematically showing a general overall structure of a polymer electrolyte fuel cell which is an embodiment of a fuel cell of the present invention. It is the cross-sectional schematic which represented typically the general whole structure of the electrolyte membrane-electrode assembly of this invention. It is a schematic sectional drawing of MEA (1) of the reference example 1. 4 is a TEM photograph of a cross section of MEA (1) in Reference Example 1. 3 is a schematic cross-sectional view of MEA (2) of Example 2. FIG. It is a schematic sectional drawing of MEA (3) of the reference example 3. 6 is a schematic cross-sectional view of MEA (4) of Example 4. FIG. 2 is a schematic cross-sectional view of a comparative MEA (1) of Comparative Example 1. FIG. 4 is a TEM photograph of a cross section of a comparative MEA (1) of Comparative Example 1. 6 is a schematic cross-sectional view of a comparative MEA (2) of Comparative Example 2. FIG. It is a schematic sectional drawing which shows the vehicle carrying the fuel cell of this invention.

  The present invention comprises an electrolyte membrane; a cathode catalyst layer disposed on one side of the electrolyte membrane; and an anode catalyst layer disposed on the other side of the electrolyte membrane. At least one of the layer and the anode catalyst layer is at least two layers, and includes a metal ion blocking catalyst layer including a hydrocarbon electrolyte disposed on the electrolyte membrane side, and a fluorine electrolyte disposed on the opposite surface side of the electrolyte membrane. The present invention relates to an electrolyte membrane-electrode assembly comprising a fluorine-containing catalyst layer.

  During operation of a fuel cell, a phenomenon (duty cycle) in which the output voltage (operating voltage) of the fuel cell varies periodically or aperiodically usually occurs due to fluctuations in the power supplied to the loader. Occurrence of the duty cycle frequently repeats oxidation and reduction reactions of the catalyst constituting the catalyst layer. In general, in view of power generation performance, platinum is mainly used for the catalyst layer. If the catalyst (for example, platinum) is kept at a constant potential even at a high potential, the catalyst surface is stable, and the elution of the catalyst to the electrolyte membrane is slight. However, when a duty cycle involving oxidation / reduction occurs, the potential of the catalyst fluctuates, and the elution of the catalyst becomes significant. When the catalyst elutes and deteriorates, the power generation performance and durability of the fuel cell are reduced. However, as described above, since the cell reaction proceeds in the catalyst layer, it is very important in terms of durability of the fuel cell to suppress / prevent deterioration of the catalyst layer. For this reason, development of the technique which suppresses deterioration of a catalyst is strongly desired.

In the present invention, the catalyst layer has a laminated structure comprising a metal ion blocking catalyst layer containing a hydrocarbon electrolyte (hydrocarbon electrolyte) and a fluorine-containing catalyst layer containing a fluorine electrolyte (fluorine electrolyte), and metal ions The barrier catalyst layer is arranged on the electrolyte membrane side. First, the MEA of the present invention can exhibit high power generation performance due to the fluorine-containing catalyst layer that is excellent in proton conductivity, heat resistance, and chemical stability. Further, the catalyst (catalyst component) in the fluorine-containing catalyst layer is eluted to the electrolyte membrane side by the occurrence of the duty cycle. However, according to the present invention, the metal ion blocking catalyst layer is provided on the electrolyte membrane side. Due to the presence of the hydrocarbon electrolyte, the eluted catalyst is trapped in the metal ion blocking catalyst layer. For this reason, in the MEA of the present invention, elution of the catalyst into the electrolyte membrane can be effectively suppressed / prevented.
On the other hand, the metal ion blocking catalyst layer functions as a catalyst layer in the first place. For this reason, the catalyst eluted from the fluorine-containing catalyst layer is trapped in the metal ion blocking catalyst layer and then reused as a catalyst. Therefore, according to the present invention, the elution of the catalyst to the electrolyte membrane can be suppressed / prevented even in the occurrence of a duty cycle, and at the same time, the catalyst eluted in the fluorine-containing catalyst layer can be effectively used in the metal ion blocking catalyst layer. it can. Therefore, the catalyst layer according to the present invention can maintain high catalytic activity for a long period of time. Therefore, the MEA of the present invention and the fuel cell using the MEA are excellent in durability and can exhibit high power generation performance.

  Embodiments of the present invention will be described below. Hereinafter, “hydrocarbon electrolyte (hydrocarbon electrolyte)” is also simply referred to as “HC electrolyte”. Similarly, “fluorine electrolyte (fluorine electrolyte)” is also simply referred to as “F electrolyte”.

  The MEA of the present invention is excellent in durability and can exhibit high power generation performance. For this reason, the MEA of the present invention is particularly preferably used for a fuel cell.

  Hereinafter, an embodiment of the MEA of the present invention and an embodiment of a fuel cell using the same will be described in detail with reference to the drawings as appropriate. However, the present invention is not limited only to the following embodiments. Each drawing is exaggerated for convenience of explanation, and the dimensional ratio of each component in each drawing may be different from the actual one. Further, in the case where the embodiment of the present invention is described with reference to the drawings, the same reference numerals are given to the same elements in the description of the drawings, and redundant description is omitted.

[Fuel cell]
The fuel cell of the present invention comprises the MEA of the present invention and a pair of separators comprising an anode side separator having a fuel gas flow path through which fuel gas flows and a cathode side separator having an oxidant gas flow path through which oxidant gas flows. Have. The fuel cell of the present invention is excellent in durability and can exhibit high power generation performance.

  FIG. 1 is a schematic cross-sectional view schematically showing a general overall structure of a polymer electrolyte fuel cell (PEFC) which is an embodiment of the fuel cell of the present invention. FIG. 1 shows a single cell of a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell 200 shown in FIG. 1 has the MEA 100 of the present invention. In the polymer electrolyte fuel cell 200, the MEA 100 is sandwiched between a pair of separators including an anode side separator 150a and a cathode side separator 150c. Here, the anode side gas diffusion layer 140a side surface of the anode side separator 150a is provided with a fuel gas flow path 152a through which fuel gas flows during operation, and the coolant flows through the opposite surface during operation. A cooling flow path (not shown) is provided. On the other hand, an oxidant gas flow path 152c through which an oxidant gas flows during operation is provided on the cathode side gas diffusion layer 140c side surface of the cathode side separator 150c, and a coolant is provided on the opposite side surface during operation. A cooling flow path (not shown) through which is circulated is provided. A gasket 160 is disposed around the polymer electrolyte fuel cell 200 so as to surround the pair of gas diffusion electrodes.

  The fuel cell having the MEA of the present invention as described above exhibits excellent durability and power generation performance. Here, 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. However, in addition to the above, an alkaline fuel cell and a direct methanol fuel cell are used. And a micro fuel cell. Among them, a polymer electrolyte fuel cell (PEFC) is preferable because it is small 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 application of the fuel cell is not particularly limited, but it is preferably applied to a vehicle. The electrolyte membrane-electrode assembly of the present invention is excellent in power generation performance and durability, and can be downsized. For this reason, the fuel cell of this invention is especially advantageous when this fuel cell is applied to a vehicle from the point of in-vehicle property.

  In particular, the polymer electrolyte fuel cell is useful as a power source for a mobile body such as an automobile in which a mounting space is limited in addition to a stationary power source. Among them, it is particularly preferable to use as a power source for a mobile body such as an automobile that requires a high output voltage after a relatively long time of operation stop.

  Hereinafter, although the member which comprises the fuel cell of this invention is demonstrated easily, the technical scope of this invention is not restrict | limited only to the following form.

[Electrolyte membrane-electrode assembly]
FIG. 2 is a schematic cross-sectional view schematically showing a general overall structure of the electrolyte membrane-electrode assembly of the present invention. As shown in FIG. 2, in the electrolyte membrane-electrode assembly 100 of the present invention, the anode catalyst layer 120 a and the cathode catalyst layer 120 c are arranged to face both surfaces of the solid polymer electrolyte membrane 110. A pair of anode side gas diffusion layer 140a and cathode side gas diffusion layer 140c is sandwiched therebetween.

  In the present invention, at least one of the cathode catalyst layer 120c and the anode catalyst layer 120a has a metal ion blocking catalyst layer containing an HC electrolyte and a fluorine-containing catalyst layer containing an F electrolyte. At this time, the metal ion blocking catalyst layer is disposed on the electrolyte membrane 110 side, and the fluorine-containing catalyst layer is disposed on the metal ion blocking catalyst layer (on the gas diffusion layer 140 side). As described above, it is sufficient that at least one of the cathode catalyst layer 120c and the anode catalyst layer 120a has the above structure. Considering the ease of ionization of the catalyst (hence, elution and precipitation problems), it is preferable that at least the cathode catalyst layer has the above structure. Thereby, the elution / precipitation of the catalyst in the cathode catalyst layer having a high potential can be effectively suppressed / prevented. However, in the MEA according to the present invention, only the anode catalyst layer may have the above structure, or both the cathode catalyst layer and the anode catalyst layer may have the above structure.

  As described above, in the present invention, at least one of the cathode catalyst layer 120c and the anode catalyst layer 120a has the above structure, and the description of each catalyst layer in the case of having the structure is the same. Therefore, in the following description, unless otherwise specified, the cathode catalyst layer and the anode catalyst layer are collectively referred to as “catalyst layer”. Similarly, the metal ion blocking catalyst layer containing the HC-based electrolyte in the catalyst layer is simply referred to as “metal ion blocking catalyst layer” and the fluorine-containing catalyst layer including the F-based electrolyte is simply referred to as “fluorine-containing catalyst”. These are referred to as “layers”, respectively. In the present specification, the “metal ion blocking catalyst layer” essentially includes an electrode catalyst and an HC-based electrolyte. The “fluorine-containing catalyst layer” essentially includes an electrode catalyst and an F-based electrolyte. This electrode catalyst is formed by supporting a catalyst component on a conductive carrier.

  As described above, the metal ion blocking catalyst layer is disposed on the electrolyte membrane side. Here, “the metal ion blocking catalyst layer is disposed on the electrolyte membrane side” means that in the thickness (cross section) direction of the catalyst layer, the electrolyte membrane, the metal ion blocking catalyst layer, the fluorine-containing catalyst layer, and the gas It means that they are arranged in the order of the diffusion layers. Therefore, the description includes not only the case where the metal ion blocking catalyst layer is disposed on the electrolyte membrane, but also the case where another layer is interposed between the metal ion blocking catalyst layer and the electrolyte membrane. Includes. Here, the “other layer” in the case where another layer is interposed is not particularly limited as long as it is a layer that does not inhibit a desired electrochemical reaction, but preferably exhibits a metal ion blocking property. Examples of such other layers include a layer obtained by removing the catalyst from the metal ion blocking catalyst layer, and preferably a layer obtained by removing the catalyst from the metal ion blocking catalyst layer. Of these, the metal ion blocking catalyst layer is preferably disposed on the electrolyte membrane. Moreover, it is preferable that a catalyst layer is comprised only from a metal ion barrier catalyst layer and a fluorine-containing catalyst layer. With this configuration, the catalyst (particularly noble metal ions) eluted from the fluorine-containing catalyst layer by the duty cycle can be trapped more efficiently by the metal ion blocking catalyst layer, and the trapped catalyst can be effectively used. Furthermore, the metal ion blocking catalyst layer and the fluorine-containing catalyst layer may each be composed of a single layer or a laminate of two or more layers.

  In the present invention, the existence form of the HC-based electrolyte is not particularly limited, and may be present in the metal ion blocking catalyst layer in a uniform or non-uniform form. Preferably, the HC electrolyte concentration in the metal ion blocking catalyst layer changes stepwise or continuously in the thickness direction. Here, the method of changing the concentration of the HC-based electrolyte is not particularly limited, and either the electrolyte membrane side or the fluorine-containing catalyst layer side is gradually increased; the HC-based electrolyte concentration in each catalyst layer is arbitrarily set Or any other form. Preferably, in the metal ion blocking catalyst layer, the HC electrolyte concentration is set so that the electrolyte membrane side is higher than the fluorine-containing catalyst layer side in the thickness direction. More preferably, in the metal ion blocking catalyst layer, the HC electrolyte concentration is set to increase stepwise or continuously from the electrolyte membrane side to the fluorine-containing catalyst layer side in the thickness direction. . Thus, by increasing the HC electrolyte concentration on the electrolyte membrane side, the catalyst eluted just before the membrane can be trapped more reliably, and the catalyst elution to the membrane can be more efficiently suppressed / prevented. Also, with such a structure, the concentration of the HC electrolyte that traps the eluted catalyst can be appropriately adjusted according to the degree of catalyst elution. Therefore, with the above structure, the catalyst (particularly, noble metal ions) eluted in the fluorine-containing catalyst layer by the duty cycle can be trapped more efficiently by the metal ion blocking catalyst layer. Moreover, the catalyst trapped here can prevent the movement in the metal ion blocking catalyst layer more. Therefore, according to the said form, it can utilize effectively as a catalyst again in a metal ion barrier catalyst layer, suppressing and preventing the elution and precipitation (especially Pt band formation) of the catalyst in an electrolyte membrane. .

  Here, in the metal ion blocking catalyst layer, the concentration gradient when the HC-based electrolyte concentration is higher on the electrolyte membrane side than on the fluorine-containing catalyst layer side in the thickness direction is not particularly limited. Considering the trapping property (metal ion blocking property) of the eluted catalyst, the ratio of the HC-based electrolyte concentration on the electrolyte membrane side to the fluorine-containing catalyst layer side is preferably 1.5 to 200 times, more preferably 3 to 20 times. Is double. With such a ratio, the eluted catalyst (especially noble metal ions) can be sufficiently trapped by the metal ion blocking catalyst layer, and the penetration of the catalyst into the electrolyte membrane can be sufficiently suppressed / prevented. In addition, the number of changes when the HC electrolyte concentration is changed in stages is not particularly limited. For example, it is preferable to change the HC electrolyte concentration 2 to 50 times, more preferably 2 to 10 times.

  The method for forming the metal ion blocking catalyst layer having different HC-based electrolyte concentrations is not particularly limited. For example, it can be achieved by preparing a predetermined number of catalyst inks having different HC-based electrolyte concentrations and sequentially laminating metal ion blocking catalyst layers using these catalyst inks so as to obtain a desired concentration gradient. Here, the metal ion blocking property can be controlled by changing the concentration of the HC electrolyte in the catalyst ink, and the ion blocking property can be changed stepwise by repeatedly applying different ion blocking catalyst layers. Is possible. By changing the metal ion blocking property in this way, the catalyst (particularly noble metal ions) eluted in the fluorine-containing catalyst layer by the duty cycle can be efficiently trapped by the metal ion blocking catalyst layer. The catalyst trapped here is prevented from moving in the metal ion blocking catalyst layer. For this reason, according to the said form, it can utilize effectively as a catalyst again in a metal ion blocking | blocking catalyst layer, and the elution and precipitation (especially Pt band formation) of the catalyst in an electrolyte membrane can be suppressed. That is, according to the said form (1), a catalyst (especially platinum) elution tolerance and high power generation property can be made compatible.

  In addition, the fluorine-containing catalyst layer is disposed on the metal ion blocking catalyst layer (on the gas diffusion layer side), that is, in a state where at least part of the fluorine-containing catalyst layer is in contact with the metal ion blocking catalyst layer. It arrange | positions on a property catalyst layer.

  Similarly, the presence state of the F-based electrolyte is not particularly limited, and may be present uniformly or non-uniformly in the fluorine-containing catalyst layer. Moreover, when it exists unevenly, the F-type electrolyte concentration in the fluorine-containing catalyst layer may change stepwise or continuously in the thickness direction. Further, the method of changing is not particularly limited, and either the electrolyte membrane side or the fluorine-containing catalyst layer side is gradually increased; the F-based electrolyte concentration in each catalyst layer is arbitrarily changed; Any form may be used. The method for forming the fluorine-containing catalyst layer having different F-based electrolyte concentrations is not particularly limited. For example, it can be achieved by preparing a predetermined number of catalyst inks having different F-based electrolyte concentrations and sequentially laminating a fluorine-containing catalyst layer using these catalyst inks so as to obtain a desired concentration gradient.

  In the present invention, the volume ratio between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer is such that the catalyst eluted from the fluorine-containing catalyst layer (particularly, noble metal ions) can be efficiently trapped by the metal ion blocking catalyst layer. If it is a ratio, it will not restrict | limit in particular. In the present specification, the “volume ratio of the metal ion blocking catalyst layer to the fluorine-containing catalyst layer” means the volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer, that is, the volume of the fluorine-containing catalyst layer. / The volume ratio of the metal ion blocking catalyst layer. Preferably, the volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer is 0.01 to 10, more preferably 2 to 5. Within such a range, the catalyst eluted from the fluorine-containing catalyst layer (especially noble metal ions) can be efficiently trapped by the metal ion blocking catalyst layer, and the eluted catalyst can be trapped by the metal ion blocking catalyst layer. It can be used effectively again.

  In the present invention, each catalyst layer has a metal ion blocking catalyst layer and a fluorine-containing catalyst layer. Here, the state of the interface between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer in each catalyst layer is not particularly limited. For example, (1) a form in which the interface between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer is clearly divided; (2) the interface between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer is not clear; There is a form in which an intermediate layer in which the concentration of each electrolyte in which the HC electrolyte and the F electrolyte are mixed is present between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer.

  According to the form of (1) above, the metal ion barrier properties are clearly different at the interface in the catalyst layer thickness (cross-sectional) direction. The form of (1) may be obtained by any method. For example, first, a metal ion blocking catalyst layer is formed on an electrolyte membrane, and then a fluorine-containing catalyst layer is formed. Can be achieved. Alternatively, this may be achieved by forming a fluorine-containing catalyst layer on a gas diffusion layer or a transfer mount and then forming a metal ion blocking catalyst layer. At this time, the formation method of the metal ion blocking catalyst layer and the fluorine-containing catalyst layer is not particularly limited, but it is desirable to prepare in a stepwise manner by a known method such as a direct coating method (for example, a spray method) or a transfer method. Thus, by clearly changing the metal ion blocking property, the catalyst (particularly, noble metal ions) eluted in the fluorine-containing catalyst layer by the duty cycle can be efficiently trapped by the metal ion blocking catalyst layer. The catalyst trapped here is prevented from moving in the metal ion blocking catalyst layer. For this reason, according to the said form, it can utilize effectively as a catalyst again in a metal ion blocking | blocking catalyst layer, and the elution and precipitation (especially Pt band formation) of the catalyst in an electrolyte membrane can be suppressed. That is, according to the said form (1), a catalyst (especially platinum) elution tolerance and high power generation property can be made compatible.

  Moreover, according to the form of (2), the elution / precipitation of the catalyst can be dispersed by changing the metal ion blocking property with a gradient in the thickness direction. Catalyst elution / precipitation and trapping can occur simultaneously in the intermediate layer. The trapped catalyst (particularly Pt ions) is prevented from moving in the intermediate layer in addition to the metal ion blocking catalyst layer. For this reason, according to the said form, it can utilize effectively as a catalyst again also in a metal ion barrier catalyst layer and an intermediate | middle layer, and can suppress the elution and precipitation (especially Pt band formation) of the catalyst in an electrolyte membrane. The form (2) may be obtained by any method. For example, after applying a catalyst ink for forming a metal ion blocking catalyst layer on an electrolyte membrane, the catalyst ink for forming a fluorine-containing catalyst layer is applied in a wet-on-wet state without forming (drying) the layer. It can be achieved by drying [form (2-1)]. The formation method of the metal ion blocking catalyst layer and the fluorine-containing catalyst layer is not particularly limited, but it is desirable to produce the metal ion blocking catalyst layer stepwise by a known method such as a direct coating method (for example, a spray method) or a transfer method. According to the said form, since a metal ion barrier property changes continuously (inclination), it can utilize as a catalyst again within a catalyst layer. Further, the catalyst (particularly Pt ions) trapped by the HC electrolyte is prevented from moving in the metal ion blocking catalyst layer. For this reason, according to the said form (2-1), the elution and precipitation (especially Pt band formation) of the catalyst in an electrolyte membrane can be suppressed. Here, the HC electrolyte concentration and the F electrolyte concentration in the intermediate layer are not particularly limited, but in the thickness direction, the HC electrolyte concentration continuously decreases from the electrolyte membrane side to the fluorine-containing catalyst layer side, The F-based electrolyte concentration is preferably continuously increased. Thus, by increasing the concentration of the HC-based electrolyte on the electrolyte membrane side, elution / precipitation of the catalyst on the membrane can be more effectively suppressed / prevented, and both the elution resistance of the catalyst (particularly platinum) and high power generation can be achieved.

  Alternatively, in the form (2) above, a metal ion blocking catalyst layer is formed on the electrolyte membrane, and an intermediate layer is formed by applying and drying a catalyst ink in which HC and F electrolytes are mixed at an appropriate ratio. Then, even if a fluorine-containing catalyst layer is formed on the intermediate layer, this can be achieved [form (2-2)]. Here, the formation method of the metal ion blocking catalyst layer, the fluorine-containing catalyst layer, and the intermediate layer is not particularly limited, but is prepared stepwise by a known method such as a direct coating method (for example, a spray method) or a transfer method. It is desirable to do.

  In the above forms (1) and (2), the metal ion blocking property can be controlled by changing the concentration of the HC electrolyte in the catalyst ink.

  According to the form of (2), the precipitation of platinum can be dispersed by changing (grading) the metal ion barrier property in a stepwise (multistage) manner. Further, the catalyst (particularly Pt ions) trapped by the HC electrolyte is prevented from moving in the metal ion blocking catalyst layer. For this reason, elution and precipitation (particularly, Pt band formation) of the catalyst in the electrolyte membrane can be suppressed. In the said form (2-2), an intermediate | middle layer may be formed in the state in which only one layer was formed between the metal ion barrier catalyst layer and the fluorine-containing catalyst layer, or two or more layers were laminated | stacked. In the latter case, the HC electrolyte concentration and the F electrolyte concentration in each layer are not particularly limited, but in the thickness direction, the HC electrolyte concentration decreases stepwise from the electrolyte membrane side to the fluorine-containing catalyst layer side. Thus, the F-based electrolyte concentration is preferably increased stepwise. Thus, by increasing the concentration of the HC-based electrolyte on the electrolyte membrane side, elution / precipitation of the catalyst on the membrane can be more effectively suppressed / prevented, and both the elution resistance of the catalyst (particularly platinum) and high power generation can be achieved.

  Further, the catalyst (electrode catalyst) concentration in the catalyst layer may be present in any form of uniform or non-uniform. Preferably, the catalyst (electrode catalyst) concentration increases stepwise or continuously from the electrolyte membrane side in the thickness direction. Here, the method of changing the catalyst (electrode catalyst) concentration is not particularly limited. For example, the catalyst concentration in the metal ion blocking catalyst layer is lowered and the catalyst concentration in the fluorine-containing catalyst layer is increased; the catalyst concentration in the metal ion blocking catalyst layer is changed from the electrolyte membrane side with respect to the thickness direction. Any method may be used such as increasing the catalyst concentration in the fluorine-containing catalyst layer stepwise or continuously from the electrolyte membrane side in the thickness direction. Of these, it is preferable to lower the catalyst concentration in the metal ion blocking catalyst layer and increase the catalyst concentration in the fluorine-containing catalyst layer. These forms may be applied singly or in appropriate combination. In addition, a specific method for changing the catalyst concentration is not particularly limited. For example, the method of changing the concentration of the HC electrolyte in the metal ion blocking catalyst layer can be used in the same manner. With such a configuration, a large number of catalysts can be arranged on the catalyst layer with good reaction efficiency (particularly on the fluorine-containing catalyst layer side), and thus an MEA with high reaction efficiency can be obtained.

  Here, in the catalyst layer, the concentration gradient when the concentration of the catalyst (electrode catalyst) increases stepwise or continuously from the electrolyte membrane side with respect to the thickness direction with respect to the thickness direction is not particularly limited. . In consideration of reaction efficiency, and therefore power generation performance, the ratio of the catalyst concentration on the fluorine-containing catalyst layer side adjacent to the gas diffusion layer with respect to the electrolyte membrane side is preferably 1.5 to 100 times, more preferably 3 to 20 times. is there. With such a ratio, the MEA can exhibit sufficient reaction efficiency and hence power generation performance. Further, the number of changes when the catalyst concentration is changed stepwise is not particularly limited. For example, the catalyst concentration is preferably changed 2 to 100 times, more preferably 2 to 10 times.

(Electrolyte membrane)
The electrolyte membrane used in the present invention is not particularly limited, and a membrane made of a known electrolyte can be used, but any member having at least proton conductivity may be used. At this time, the electrolyte membrane preferably contains a polymer having a proton dissociable functional group. In the present specification, the “proton dissociable group” means a functional group from which a hydrogen atom can be ionized as a proton (H ⁺ ) and separated. The proton dissociating functional group is not particularly limited, for example, a sulfonic group _(-SO 3 H), such as a phosphonic acid group _[-PO 3 _{H 2]} are preferably exemplified. Specifically, an electrolyte such as phosphoric acid or ionic liquid is formed on a porous thin film formed of a fluorine-based electrolyte membrane, a hydrocarbon-based electrolyte membrane, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or the like. Well-known solid polymer electrolyte membranes such as membranes impregnated with components, membranes in which a polymer microporous membrane is impregnated with a liquid electrolyte, membranes in which a porous body is filled with a polymer electrolyte, etc. Can be used.

  Among these, as a fluorine-type electrolyte membrane, it does not restrict | limit in particular, A well-known fluorine-type electrolyte membrane is used. Specifically, as the fluorine-based electrolyte having a proton dissociative functional group constituting the fluorine-based electrolyte membrane, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), Flemion ( (Registered trademark, manufactured by Asahi Glass Co., Ltd.), etc., perfluorocarbon sulfonic acid polymers, polytrifluorostyrene sulfonic acid polymers, perfluorocarbon phosphonic acid polymers, trifluorostyrene sulfonic acid polymers, ethylenetetrafluoroethylene-g-styrene sulfone. An acid-based polymer, an ethylene-tetrafluoroethylene copolymer, a polyvinylidene fluoride-perfluorocarbon sulfonic acid-based polymer, an ion exchange resin manufactured by Dow Chemical Company, an ethylene-tetrafluoroethylene copolymer, and trifluorostyrene. A resin to polymer are mentioned as suitable examples. From the viewpoint of power generation performance such as heat resistance and chemical stability, these fluorine-based electrolyte membranes are preferably used, and particularly preferably a fluorine-based electrolyte membrane composed of a perfluorocarbon sulfonic acid polymer.

  Also, the hydrocarbon film is not particularly limited, and a known hydrocarbon electrolyte film is used. Specifically, a hydrocarbon-based resin film having a sulfonic acid group, a hydrocarbon polymer compound doped with an inorganic acid such as phosphoric acid, an organic partially substituted with a functional group of a proton conductor / Inorganic hybrid polymer, proton conductor impregnated with phosphoric acid solution or sulfuric acid solution in polymer matrix is used, but considering oxidation resistance, low gas permeability, ease of production and low cost, A hydrocarbon film having a sulfonic acid group is preferred. The hydrocarbon-based membrane used in the present invention is not particularly limited, and a known hydrocarbon-based electrolyte membrane is used. For example, poly (trifluorostyrene) sulfonic acid, polyvinylphosphonic acid, polyvinylcarboxylic acid, Polyvinyl sulfonic acid polymer, polyphenylene oxide, polyphenylene sulfoxide, polyphenylene sulfide, polyphenylene sulfide sulfone, polysulfone, polysulfonic acid, polyaryl ether ketone sulfonic acid, polybenzimidazole alkyl sulfonic acid, polybenzimidazole alkylphosphonic acid, polystyrene sulfonic acid, polyether Ether ketone sulfonic acid, polyphenyl sulfonic acid, sulfonated polyether sulfone (s-PES), sulfonated polyaryl ether ketone, sulfonated poly Lens imidazole alkyl, phosphonated polybenzimidazole alkyl, sulfonated polystyrene, sulfonated polyether ether ketone (s-PEEK), etc. sulfonated polyphenylene are mentioned as suitable examples. These hydrocarbon-based electrolyte membranes are preferably used from the viewpoint of production such that the raw material is inexpensive, the production process is simple, and the selectivity of the material is high. In addition, as for the electrolyte (ion exchange resin) mentioned above, only 1 type may be used independently and 2 or more types may be used together. Moreover, it is needless to say that other materials may be used without being limited to the above-described materials.

  Among these, the electrolyte membrane preferably contains a fluorine atom because of excellent heat resistance, chemical stability, and the like. Among these, fluorine electrolytes such as Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) and the like are preferable. In particular, in the present invention, when a polymer electrolyte having a sulfonic acid group such as Nafion (registered trademark, manufactured by DuPont) is used, it is preferable to use one having an EW of about 600 to 1100. In addition, EW (Equivalent Weight) represents the dry film weight per 1 mol of sulfonic acid groups, and means that the specific gravity of sulfonic acid groups is larger as it is smaller.

  The thickness of the electrolyte membrane may be appropriately determined in consideration of the characteristics of the MEA incorporating the membrane or the solid electrolyte fuel cell (PEFC), and is not particularly limited. However, the thickness of the electrolyte membrane is preferably 5 to 300 μm, more preferably 10 to 200 μm, still more preferably 15 to 150 μm, and particularly preferably 30 to 50 μm. When the thickness is within such a range, the balance of strength during film formation, durability during use, and output characteristics during use can be appropriately controlled.

(Catalyst layer)
The catalyst layer according to the present invention includes a metal ion blocking catalyst layer disposed on the electrolyte membrane side and containing an HC electrolyte, and a fluorine-containing catalyst layer disposed on the metal ion blocking catalyst layer and including an F electrolyte. . Here, both the metal ion blocking catalyst layer and the fluorine-containing catalyst layer include an electrode catalyst in which a catalyst component is supported on a conductive support. In the following, after describing the portions common to the metal ion blocking catalyst layer and the fluorine-containing catalyst layer, the HC electrolyte used for the metal ion blocking catalyst layer and the F-based electrolyte used for the fluorine-containing catalyst layer will be described. To do.

  Here, the catalyst components used in the cathode catalyst layer and the anode catalyst layer are not particularly limited, and known catalysts can be used in the same manner. For example, the catalyst component used for the cathode catalyst layer is not particularly limited as long as it has a catalytic action for oxygen reduction reaction, and the catalyst component used for the anode catalyst layer has a catalytic action for hydrogen oxidation reaction. If there is no restriction in particular. Specifically, metals such as platinum, ruthenium, iridium, rhodium, palladium, osmium, rhenium, gold, silver, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and the like Selected from such alloys. Of these, the catalyst layer preferably contains a noble metal as a catalyst component in order to improve catalyst activity, poisoning resistance to carbon monoxide, heat resistance, and the like. Here, the noble metal is not particularly limited, but preferably includes platinum, rhodium, palladium, iridium, osmium, ruthenium, rhenium, gold and silver, and alloys thereof. Of these, those containing at least platinum are particularly preferably used. 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. In general, an alloy is a generic term for a metal element having one or more metal elements or non-metal elements added and having metallic properties. The alloy structure consists of a eutectic alloy, which is a mixture of the component elements as separate crystals, a component element completely melted into a solid solution, and a component element composed of 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 determined from the half width of the diffraction peak of the catalyst component in X-ray diffraction. Can be measured.

  The catalyst component (catalyst particles) is supported on a conductive carrier and becomes an electrode catalyst. Here, 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. Carbon is preferred. 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. When the specific surface area of the conductive support is within this range, the balance between the dispersibility of the catalyst component on the conductive support and the effective utilization rate of the catalyst component can be appropriately controlled.

  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 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 the same polymer electrolyte as that used for the electrolyte membrane can be used. The polymer electrolyte used for the electrolyte membrane and the polymer electrolyte used for each catalyst layer may be the same or different.

  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.

  As such commercially available products, for example, electrode catalysts such as those manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., N.E. Chemcat, E-TEK, and Johnson Matthey can be used. These electrode catalysts are obtained by supporting platinum or a platinum alloy on a carbon carrier (supporting concentration of catalyst species: 20 to 70% by mass). In the above, as the carbon carrier, ketjen black, vulcan, acetylene black, black pearl, graphitized carbon carrier (for example, graphitized ketjen black) previously heat treated at high temperature, carbon nanotube, carbon nanohorn, carbon fiber, There is mesoporous carbon.

(Metal ion blocking catalyst layer)
In the MEA of the present invention, the metal ion blocking catalyst layer is disposed on the electrolyte membrane side and includes an HC electrolyte.

The HC-based electrolyte used in the present invention is not particularly limited, and a known electrolyte can be used, but at least proton conductivity. At this time, the HC electrolyte preferably includes a polymer having a proton dissociable functional group. The proton dissociative functional group is not particularly limited, and examples thereof include a sulfonic acid group (—SO ₃ H), a phosphonic acid group [—PO (OH) ₂ ], a carboxyl group (—COOH), and —POH (OH). , -Ph (OH) (Ph represents a phenyl group) and the like. Of these, the proton dissociative functional group is preferably a super strong acid group. Here, the “super strong acid” is an acid that is more acidic than 100% sulfuric acid, and includes, for example, a sulfonic acid group (—SO ₃ H).

  Specifically, the HC electrolyte includes a hydrocarbon resin having a sulfonic acid group, a hydrocarbon polymer compound doped with an inorganic acid such as phosphoric acid, and a part of the functional group of a proton conductor. The organic / inorganic hybrid polymer substituted with (1), a proton conductor in which a polymer matrix is impregnated with a phosphoric acid solution or a sulfuric acid solution are used. More specifically, poly (trifluorostyrene) sulfonic acid, polyvinyl phosphonic acid, polyvinyl carboxylic acid, polyvinyl sulfonic acid polymer, polyphenylene oxide, polyphenylene sulfoxide, polyphenylene sulfide, polyphenylene sulfide sulfone, polysulfone, polysulfonic acid, polyaryl ether ketone. Sulfonic acid, polybenzimidazole alkyl sulfonic acid, polybenzimidazole alkyl phosphonic acid, polystyrene sulfonic acid, polyether ether ketone sulfonic acid, polyphenyl sulfonic acid, sulfonated polyether sulfone (s-PES), sulfonated polyaryl ether ketone Sulfonated polybenzimidazole alkyl, phosphonated polybenzimidazole alkyl, sulfonated polystyrene Emissions, sulfonated polyether ether ketone (s-PEEK), etc. sulfonated polyphenylene are mentioned as suitable examples. These HC-based electrolytes are advantageous in that the raw materials are inexpensive, the manufacturing process is simple, and the material selectivity is high. In addition, only 1 type may be used independently for the HC electrolyte (ion exchange resin) mentioned above, and 2 or more types may be used together. Moreover, it is needless to say that other materials may be used without being limited to the above-described materials. Among these, in view of oxidation resistance, low gas permeability, ease of production, low cost, and the like, hydrocarbon electrolytes having super strong acid groups (particularly sulfonic acid groups) (particularly aromatic electrolytes) are preferable. As such an HC electrolyte, sulfonated polyethersulfone (s-PES) and sulfonated polyetheretherketone (s-PEEK) are particularly preferable.

  The metal ion blocking catalyst layer includes an electrode catalyst. Here, the content of the electrode catalyst in the metal ion blocking catalyst layer is not particularly limited, but is preferably 10 to 60% by mass in the catalyst layer (in terms of solid content).

  The method for forming the metal ion blocking catalyst layer is not particularly limited, and a known method such as a direct coating method (for example, a spray method) or a transfer method can be used as it is or appropriately modified.

  The thickness of the metal ion blocking catalyst layer can be appropriately determined in consideration of the characteristics of the obtained fuel cell, and the thickness should be a volume ratio with the fluorine-containing catalyst layer as described above. preferable. Usually, the thickness of the metal ion blocking catalyst layer is preferably 0.001 to 50 μm, more preferably 0.01 to 40 μm, still more preferably 0.1 to 30 μm, and particularly preferably 1 to 25 μm. Within this range, the catalyst (especially noble metal ions) eluted in the fluorine-containing catalyst layer can be sufficiently trapped by the duty cycle, and can be effectively used again as a catalyst. Precipitation (particularly, Pt band formation) can be suppressed.

(Fluorine-containing catalyst layer)
In the MEA of the present invention, the fluorine-containing catalyst layer is disposed on the metal ion blocking catalyst layer and contains an F-based electrolyte.

  The F-based electrolyte used in the present invention is not particularly limited, and a known fluorine electrolyte can be used, but it has at least proton conductivity. Specifically, as a fluorine electrolyte having a proton dissociable functional group constituting the fluorine electrolyte, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), Flemion (registered trademark, Asahi Glass Co., Ltd.), etc., perfluorocarbon sulfonic acid polymers, polytrifluorostyrene sulfonic acid polymers, perfluorocarbon phosphonic acid polymers, trifluorostyrene sulfonic acid polymers, ethylenetetrafluoroethylene-g-styrene sulfonic acid polymers , Ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride-perfluorocarbon sulfonic acid polymer, Dow Chemical's ion exchange resin, ethylene-tetrafluoroethylene copolymer, trifluorostyrene-based poly A resin to be over are mentioned as suitable examples. These fluorine electrolytes have the advantage of being excellent in heat resistance, chemical stability, and the like. Of these, a perfluorocarbon sulfonic acid polymer is preferably used from the viewpoint of power generation performance. In addition, as for the F type electrolyte mentioned above, only 1 type may be used independently and 2 or more types may be used together. Moreover, it is needless to say that other materials may be used without being limited to the above-described materials.

  The fluorine-containing catalyst layer includes an electrode catalyst. Here, the content of the electrode catalyst in the fluorine-containing catalyst layer is not particularly limited, but is preferably 10 to 60% by mass in the catalyst layer (in terms of solid content).

  The method for forming the fluorine-containing catalyst layer is not particularly limited, but a known method such as a direct coating method (for example, spray method) or a transfer method can be used as it is or after being appropriately modified.

  The thickness of the fluorine-containing catalyst layer can be appropriately determined in consideration of the characteristics of the obtained fuel cell, and the thickness should be a volume ratio with the metal ion blocking catalyst layer as described above. preferable. Usually, the thickness of the fluorine-containing catalyst layer is preferably 1 to 300 μm, more preferably 5 to 50 μm. If it is such a range, sufficient electric power generation amount can be obtained and a high output can be maintained.

  Next, a method for forming the metal ion blocking catalyst layer and the fluorine-containing catalyst layer will be specifically described. In addition, this invention is not limited by the following method, You may modify the following method suitably or may use another method. In the following method, the metal ion blocking catalyst layer and the fluorine-containing catalyst layer may be formed by the same method or conditions, or by different methods and conditions.

  Specifically, the MEA of the present invention can be produced by a known method such as a direct coating method or a transfer method. A preferred embodiment of the direct coating method is as follows. First, a catalyst ink (1) is prepared by mixing the electrode catalyst, HC polymer electrolyte and solvent as described above, and this is applied onto the electrolyte membrane, thereby forming a metal ion blocking catalyst layer. Next, in the same manner, a catalyst ink (2) is prepared by mixing the above-described electrode catalyst, F-based polymer electrolyte and solvent, and this is applied onto the metal ion blocking catalyst layer formed above. By doing so, a fluorine-containing catalyst layer is formed. The process is repeated for the other surface of the electrolyte membrane to form a cathode catalyst layer and an anode catalyst layer on the electrolyte membrane, respectively. Thereby, MEA which consists of a catalyst layer and an electrolyte membrane can be obtained.

  A preferred embodiment of the transfer method is as follows. First, the fluorine-containing catalyst layer is formed by applying a catalyst ink (1 ') composed of the electrode catalyst, the F-based polymer electrolyte and the solvent as described above to a transfer mount or a gas diffusion layer. Next, in the same manner, a catalyst ink (2 ′) is prepared by mixing the above-described electrode catalyst, HC polymer electrolyte and solvent, and this is applied onto the fluorine-containing catalyst layer formed above. Thus, a metal ion blocking catalyst layer is formed. This process is repeated to form a cathode catalyst layer and an anode catalyst layer on the transfer mount or gas diffusion layer, respectively. Further, after sandwiching the electrolyte membrane between the two catalyst layers thus prepared, hot pressing is performed on the laminate. At this time, the hot press conditions are not particularly limited as long as the catalyst layer and the electrolyte membrane can be joined sufficiently closely, but are 100 to 200 ° C., more preferably 110 to 170 ° C., and 1 to 5 MPa with respect to the electrode surface. It is preferable to carry out at a pressing pressure of. Thereby, the bondability between the polymer electrolyte membrane and the catalyst layer can be enhanced. After performing hot pressing, if necessary, the transfer mount is peeled off to obtain an MEA comprising a catalyst layer and an electrolyte membrane.

  In the said method, it does not restrict | limit especially as a solvent, The normal solvent used for forming a catalyst layer can be used similarly. Specifically, water such as pure water, ultrapure water, ion exchange water, filtered water; lower alcohols such as cyclohexanol, ethanol, n-propanol, and isopropanol can be used. These solvents may be used alone or in the form of a mixture of two or more. 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 may contain a thickener. The use of a thickener is effective particularly when the catalyst ink cannot be applied well onto the transfer mount in the transfer method. 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). 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 20 with respect to the total mass of the catalyst ink. % By mass.

  The catalyst ink may contain a water repellent. As a result, the water repellency can be further increased to suppress / prevent flooding and the like. 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. The amount of the water repellent added when the water repellent 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 20 with respect to the total mass of the catalyst ink. % By mass.

  In the above transfer method, the transfer mount is not particularly limited, and 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 step, the thickness of the 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). Can be used. The method for applying the catalyst ink 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.

  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 in which the electrolyte is previously prepared in the other solvent (for example, Nafion (registered trademark) manufactured by DuPont: Nafion (registered trademark) dispersed in 1-propanol at a concentration of 5 wt% / The suspension) may be used in the above method as it is.

  The conditions for forming the catalyst layer are not particularly limited, and can be used in the same manner as known methods or with appropriate modifications. For example, the catalyst ink is applied on a predetermined substrate (electrolyte film, transfer mount, metal ion blocking catalyst layer, fluorine-containing catalyst layer) so that the thickness after drying becomes the predetermined thickness as described above. To do. Next, this coating film is dried in a vacuum dryer or under reduced pressure at 25 to 120 ° C., more preferably 50 to 80 ° C., for 5 to 60 minutes, more preferably 10 to 40 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.

(Gas diffusion layer)
The MEA according to the present invention may generally further comprise a gas diffusion layer. At this time, when the direct coating method is used in the above method, each catalyst layer is previously formed on the surface of the gas diffusion layer to produce a catalyst layer-gas diffusion layer assembly, and then the same as described above. The electrolyte membrane can be sandwiched and joined by hot pressing with this catalyst layer-gas diffusion layer assembly. Alternatively, a gas diffusion layer may be formed on each catalyst layer formed on both surfaces of the electrolyte membrane. In the case of the transfer method, the transfer mount is peeled off, and the obtained joined body is further sandwiched between gas diffusion layers, so that the catalyst layer and the electrolyte membrane can be further joined to each catalyst layer.

  At this time, the gas diffusion layer used in the MEA is not particularly limited, and known ones can be used in the same manner. Examples thereof include those based on a sheet-like material having conductivity and porosity such as carbon woven fabrics such as glassy carbon, paper-like paper bodies, felts and nonwoven fabrics. 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. With such a thickness, sufficient mechanical strength and permeability such as gas and water can be obtained.

  The method for forming the 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 a 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, It is fluorine-type, such as a polytetrafluoroethylene (PTFE), a polyvinylidene fluoride (PVDF), a polyhexafluoropropylene, a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). 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 (carbon particles: water repellent). .

  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.

  The method for forming the carbon particle layer on the substrate in the gas diffusion layer is not particularly limited, and for example, the following method can be used. A slurry is prepared by dispersing carbon particles, a water repellent, and the like in a solvent such as water, an alcohol solvent such as perfluorobenzene, dichloropentafluoropropane, methanol, and ethanol. Next, the slurry may be applied on a substrate and dried, or the slurry may be dried once and pulverized to form a powder, which may be applied onto the gas diffusion layer. 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 catalyst layer, the electrolyte membrane, and preferably the gas diffusion layer is not limited to the method described above. That is, a method in which a catalyst ink is applied and dried on an electrolyte membrane, followed by hot pressing, the catalyst layer is joined to a solid electrolyte membrane, and the obtained joined body is sandwiched between gas diffusion layers to form MEA; Ink may be applied to the gas diffusion layer and dried to form a catalyst layer, which may be bonded to the electrolyte membrane by hot pressing, or any other known technique may be used as appropriate.

  The electrolyte membrane-electrode assembly of the present invention and the electrolyte membrane-electrode assembly produced by the method of the present invention are included in the corrosion of the carbon support used as the catalyst support and the electrolyte membrane-electrode assembly as described above. It is possible to suppress deterioration of the electrolyte component. 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.

(Separator)
The separator has a function of electrically connecting each cell in series when a plurality of single cells of a fuel cell such as a polymer electrolyte fuel cell are connected in series to form a fuel cell stack. The separator also functions as a partition that separates the fuel gas, the oxidant gas, and the coolant from each other. Therefore, as described above, each separator is provided with a gas flow path and a cooling flow path. As a material constituting the separator, conventionally known materials such as dense carbon graphite, carbon such as a carbon plate, and metal such as stainless steel can be appropriately employed without limitation. The thickness and size of the separator and the shape and size of each flow path provided are not particularly limited, and can be appropriately determined in consideration of the desired output characteristics of the obtained fuel cell.

(gasket)
The gasket is disposed around the fuel cell so as to surround the pair of catalyst layers and the gas diffusion layer, and has a function of preventing the gas supplied to the catalyst layer from leaking to the outside. A gas diffusion electrode refers to a joined body of a gas diffusion layer and an electrode catalyst layer. The material constituting the gasket is not particularly limited, but rubber materials such as fluoro rubber, silicon rubber, ethylene propylene rubber (EPDM), polyisobutylene rubber, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), Examples thereof include fluorine polymer materials such as polyhexafluoropropylene and tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and thermoplastic resins such as polyolefin and polyester. Moreover, there is no restriction | limiting in particular also in the thickness of a gasket, Preferably it is 50 micrometers-2 mm, More preferably, what is necessary is just to be about 100 micrometers-1 mm.

[vehicle]
The vehicle 300 (see FIG. 11) on which the above-described fuel cell (including the fuel cell stack) 200 of the present invention is mounted is also included in the technical scope of the present invention. For example, a polymer electrolyte fuel cell (PEFC) or a stack type fuel cell to which the present invention is applied is very excellent in output performance, and is suitable for vehicle applications that require high output. Further, since the vehicle 300 equipped with the fuel cell 200 according to the present invention is equipped with a fuel cell that can be cut in a stacked state, the production cycle of the fuel cell unit can be shortened and the productivity of the fuel cell vehicle can be improved. .

  The fuel cell and fuel cell stack of the present invention are extremely excellent in durability and performance.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

Reference example 1
1. Preparation of catalyst ink for forming fluorine-containing catalyst layer 20 mg of platinum catalyst, 19 ml of ultrapure water, 6 ml of isopropyl alcohol and 0.5 wt% Nafion (registered trademark) dispersion solution as F-based electrolyte (manufactured by DuPont Co., Ltd., DE2020CS) 100 μl was added to prepare a mixture. The obtained mixed liquid was subjected to ultrasonic treatment for 30 minutes to obtain catalyst ink (1). Note that platinum-supported carbon (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., TEC10E50E, platinum content 46% by mass) was used as the platinum catalyst.

2. Preparation of catalyst ink for forming metal ion blocking catalyst layer To 20 mg of platinum catalyst, 19 ml of ultrapure water, 6 ml of isopropyl alcohol and 100 μl of 0.5 wt% s-PES solution as HC electrolyte were added to prepare a mixed solution. The obtained mixed liquid was subjected to ultrasonic treatment for 30 minutes to obtain catalyst ink (2). In addition, the platinum catalyst described above is 1. Is the same. Moreover, s-PES used here is a sulfonated polyethersulfone having the following structural formula having a weight average molecular weight of 80,000 to 160,000 (polyethylene glycol (PEG) conversion).

3. Formation of fluorine-containing catalyst layer 10 μl of the catalyst ink (1) prepared in (1) was applied on a glassy carbon electrode (application area = about 0.2 cm ² ) as a gas diffusion layer using a micropipette and dried at 60 ° C. for 10 minutes. As a result, a fluorine-containing catalyst layer having a Pt loading of 15 μg / cm ² and an average thickness of 5 μm was formed on the gas diffusion layer.

4). Formation of metal ion blocking catalyst layer 2. 2 μl of the catalyst ink (2) prepared in step 3 above was added. The metal-blocking catalyst layer was formed on the fluorine-containing catalyst layer by coating with a micropipette on the fluorine-containing catalyst layer formed in step 1 and drying at 60 ° C. for 10 minutes.

5. 2. Production of MEA And 4. By repeating the operation, a laminate (1) in which a glassy carbon electrode, a fluorine-containing catalyst layer, and a metal ion blocking catalyst layer were sequentially formed was produced in the same manner. A solid polymer electrolyte membrane (manufactured by DuPont, trade name: NRE211CS, thickness: 25 μm) was dried for 10 minutes at 60 ° C. of these two laminates (1) to produce an electrode (1). As a result, a metal ion blocking catalyst layer having a Pt loading of 15 μg / cm ² and an average thickness of 1 μm was formed on the fluorine-containing catalyst layer. The volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer is 5.

  Moreover, it produced on the conditions similar to an electrode (1), and observed the cross section after performing a catalyst dissolution test by TEM. The results are shown in FIG. The electrode (1) had a structure in which a glassy carbon electrode, a fluorine-containing catalyst layer, and a metal ion blocking catalyst layer were sequentially formed as shown in FIG. Here, in the laminate (1), the interface between the fluorine-containing catalyst layer and the metal ion blocking catalyst layer was clearly divided. As is clear from FIG. 4, almost no elution of the catalyst (platinum) was observed at the interface (inside the square in the figure) between the electrolyte membrane and the metal ion blocking catalyst layer.

Example 2
1. Formation of fluorine-containing catalyst layer Reference Example 1 above. 10 μl of the catalyst ink (1) prepared in the above was applied on a glassy carbon electrode (application area = about 0.2 cm ² ) as a gas diffusion layer using a micropipette. In this step, the coated surface of the catalyst ink (1) was not dried.

2. Formation of metal ion blocking catalyst layer Reference Example 1 2 μl of the catalyst ink (2) prepared in step 3 above was added. The catalyst ink (1) formed in (1) was applied on a wet on wet surface using a micropipette and then dried at 60 ° C. for 10 minutes to produce a laminate (2). As a result, a fluorine-containing catalyst layer having a Pt loading of 15 μg / cm ² and an average thickness of 10 μm was formed on the gas diffusion layer. Further, a metal ion blocking catalyst layer having a Pt loading of 15 μg / cm ² and an average thickness of 2 μm was formed on the fluorine-containing catalyst layer. The volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer is 5.

  As shown in FIG. 5, this laminate (2) had a structure in which a glassy carbon electrode, a fluorine-containing catalyst layer, and a metal ion blocking catalyst layer were sequentially formed. The interface between the fluorine-containing catalyst layer and the metal ion blocking catalyst layer is not clear, and an intermediate layer in which the concentration of each electrolyte is mixed between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer with the HC electrolyte and F electrolyte mixed. Existed.

Reference example 3
1. Preparation of catalyst ink for forming fluorine-containing catalyst layer 20 mg of palladium catalyst, 19 ml of ultrapure water, 6 ml of isopropyl alcohol and 0.5 wt% Nafion (registered trademark) dispersion solution as F-based electrolyte (manufactured by DuPont, DE521CS) 100 μl was added to prepare a mixture. The obtained mixed liquid was subjected to ultrasonic treatment for 30 minutes to obtain catalyst ink (3). The palladium catalyst is formed by supporting Pd particles having an average particle size of 30 nm on a ketjen black (BET surface area = 50 m ² / g) as a conductive carrier in a loading amount of 50% by mass.

2. Preparation of catalyst ink for forming metal ion blocking catalyst layer To 20 mg of palladium catalyst, 19 ml of ultrapure water, 6 ml of isopropyl alcohol and 100 μl of 0.5 wt% s-PES solution as HC electrolyte were added to prepare a mixed solution. The obtained mixed liquid was subjected to ultrasonic treatment for 30 minutes to obtain catalyst ink (4). The palladium catalyst is the same as in the above 1. Is the same. The s-PES solution was used in Reference Example 1. It is the same as the s-PES solution used in 1.

3. Formation of fluorine-containing catalyst layer 10 μl of the catalyst ink (3) prepared in the above was applied on a glassy carbon electrode (application area = about 0.2 cm ² ) as a gas diffusion layer using a micropipette and dried at 60 ° C. for 10 minutes. As a result, a fluorine-containing catalyst layer having a Pd carrying amount of 15 μg / cm ² and an average thickness of 10 μm was formed on the gas diffusion layer.

4). Formation of metal ion blocking catalyst layer 2. 2 μl of the catalyst ink (4) prepared in step 3 above was added. The laminate (3) was produced by applying the solution on the fluorine-containing catalyst layer formed in Step 1 using a micropipette and drying at 60 ° C. for 10 minutes. As a result, a metal ion blocking catalyst layer having a Pd loading of 15 μg / cm ² and an average thickness of 2 μm was formed on the fluorine-containing catalyst layer. Here, in the laminate (3), the interface between the fluorine-containing catalyst layer and the metal ion blocking catalyst layer was clearly divided. The volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer is 5.

  As shown in FIG. 6, this laminate (3) had a structure in which a glassy carbon electrode, a fluorine-containing catalyst layer, and a metal ion blocking catalyst layer were sequentially formed. In the laminate (3), the interface between the fluorine-containing catalyst layer and the metal ion blocking catalyst layer was clearly divided and formed.

Example 4
1. Formation of fluorine-containing catalyst layer Reference Example 3 1. 10 μl of the catalyst ink (3) prepared in the above was applied onto a glassy carbon electrode (application area = about 0.2 cm ² ) using a micropipette. In this step, the coated surface of the catalyst ink (3) was not dried.

2. Formation of metal ion blocking catalyst layer Reference Example 3 above 2 μl of the catalyst ink (4) prepared in 1 above was added. The catalyst ink (3) formed in (1) was coated on the wet surface using a micropipette and then dried at 60 ° C. for 10 minutes to produce a laminate (4). As a result, a fluorine-containing catalyst layer having a Pd carrying amount of 15 μg / cm ² and an average thickness of 10 μm was formed on the gas diffusion layer. Further, a metal ion blocking catalyst layer having a Pd loading of 15 μg / cm ² and an average thickness of 2 μm was formed on the fluorine-containing catalyst layer. The volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer is 5.

  As shown in FIG. 7, this laminate (4) had a structure in which a glassy carbon electrode, a fluorine-containing catalyst layer, and a metal ion blocking catalyst layer were sequentially formed. The interface between the fluorine-containing catalyst layer and the metal ion blocking catalyst layer is not clear, and an intermediate layer in which the concentration of each electrolyte is mixed between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer with the HC electrolyte and F electrolyte mixed. Existed.

Comparative Example 1
Reference Example 1 above. 10 μl of the catalyst ink (1) prepared in step 1 was applied onto a glassy carbon electrode (application area = about 0.2 cm 2) as a gas diffusion layer using a micropipette, dried at 60 ° C. for 10 minutes, and then subjected to comparative lamination. A body (1) was produced. This operation was repeated to produce another comparative laminate (1). A solid polymer electrolyte membrane (manufactured by DuPont, trade name: DE521CS, thickness: 0.1 μm) is sandwiched between these two comparative laminates (1) and dried at 60 ° C., whereby the comparative electrode (1) is obtained. Manufactured. As a result, a fluorine-containing catalyst layer having a Pt loading of 15 μg / cm 2 and an average thickness of 0.1 μm was formed on the glassy carbon electrode.

  The cross section of this comparative MEA (1) was observed by TEM. The results are shown in FIG. The comparative MEA (1) had a structure in which only the fluorine-containing catalyst layer was formed on the glassy carbon electrode as shown in FIG. Further, as is apparent from FIG. 9, the elution (black spots) of the catalyst (platinum) was considerably observed at the interface (inside the square in the figure) between the electrolyte membrane and the metal ion blocking catalyst layer.

Comparative Example 2
Reference Example 3 above 10 μl of the catalyst ink (3) prepared in Step 1 was applied onto a glassy carbon electrode (application area = about 0.2 cm ² ) as a gas diffusion layer using a micropipette and dried at 60 ° C. for 10 minutes. Ten comparative laminates (2) were produced. As a result, a fluorine-containing catalyst layer having a Pd loading of 15 μg / cm ² and an average thickness of 0.1 μm was formed on the gas diffusion layer.

  As shown in FIG. 10, this comparative laminate (2) had a structure in which only the fluorine-containing catalyst layer was formed on the glassy carbon electrode.

(Electrochemical evaluation test)
Regarding the MEAs (1) to (4) and the comparative MEAs (1) to (2) prepared in Reference Examples 1 and 3, Examples 2 and 4 and Comparative Examples 1 and 2, the electrochemical characteristics were as follows. evaluated. That is, each sample (half-cell catalyst electrode layer) was subjected to a potential sweep with a potentiostat in a 0.1 M HClO 4 solution saturated with oxygen at 25 ° C. At this time, the potential sweep condition by the potentiostat was performed from 0.2 V to 1.2 V at an operation speed of 10 mV / s. Here, 0.9Vvs. The current at RHE was determined. Further, the mass activity (A / g-catalyst) was obtained by correcting the influence of oxygen diffusion using the limiting current and defining it by the catalyst weight in the catalyst layer. This mass activity is used as an index of oxygen reduction activity.

(Durability evaluation test)
The durability of the MEAs (1) to (4) and the comparative MEAs (1) to (2) produced in Reference Examples 1 and 3, Examples 2 and 4 and Comparative Examples 1 and 2 was evaluated as follows. did. That is, each sample (half-cell catalyst electrode layer) was subjected to mass activity before and after the 10,000 cycle test using a rectangular wave of 0.6 to 1.0 V, 3 s in a nitrogen saturated 0.1 M HClO4 at 60 ° C. The reduction rate (%) of the catalyst was determined, and the catalyst metal dissolution resistance was measured.

  The electrochemical evaluation test and durability evaluation test are shown in Table 1 below.

  From the results of Table 1 above, it can be seen that the MEA of the present invention has a significantly lower mass activity reduction rate than the comparative MEA.

100 MEA,
110 solid polymer electrolyte membrane,
120a anode catalyst layer,
120c cathode catalyst layer,
140a anode side gas diffusion layer,
140c cathode side gas diffusion layer,
150a anode side separator,
150c cathode side separator,
152a fuel gas flow path,
152c oxidant gas flow path,
160 gasket,
200 Solid polymer fuel cell.

Claims (9)

An electrolyte membrane;
A cathode catalyst layer and a cathode-side gas diffusion layer, which are sequentially disposed on one side of the electrolyte membrane;
An anode catalyst layer and an anode-side gas diffusion layer sequentially disposed on the other side of the electrolyte membrane;
And having
At least one of the cathode catalyst layer and the anode catalyst layer is
At least two layers,
And the fluorine-containing catalyst layer having only fluorine electrolyte as the electrolyte, and the fluorine-containing catalytic layer metal ion blocking catalyst layer containing a hydrocarbon electrolyte disposed electrolyte membrane side than Ri Tona,
An electrolyte membrane-electrode assembly , in which an intermediate layer having a gradient in each electrolyte concentration in which a hydrocarbon electrolyte and a fluorine electrolyte are mixed exists between the metal ion blocking catalyst layer and the fluorine-containing catalyst layer .   The electrolyte membrane-electrode assembly according to claim 1, wherein the hydrocarbon electrolyte contained in the metal ion blocking catalyst layer is an aromatic electrolyte having a super strong acid group.   The volume ratio of the fluorine-containing catalyst layer to the metal ion blocking catalyst layer (= ratio of the volume of the fluorine-containing catalyst layer / the volume of the metal ion blocking catalyst layer) is 0.01 to 10. 2. The electrolyte membrane-electrode assembly according to 1. The catalyst layer is
A catalyst for forming a fluorine-containing catalyst layer is formed in a wet-on-wet state without applying (drying) a metal ion-blocking catalyst layer after applying a metal ion-blocking catalyst layer-forming catalyst ink on the electrolyte membrane. By applying ink and drying; or
After applying the fluorine-containing catalyst layer forming catalyst ink on the gas diffusion layer, the metal ion blocking catalyst layer forming catalyst ink is formed in a wet-on-wet state without forming (drying) the fluorine-containing catalyst layer. By applying and drying;
The electrolyte membrane-electrode assembly according to any one of claims 1 to 3 , which is formed . The electrolyte membrane-electrode assembly according to any one of claims 1 to 4 , wherein the cathode catalyst layer and the anode catalyst layer contain a noble metal as a catalyst component. The electrolyte membrane according to claim 5 , wherein the noble metal is at least one metal selected from the group consisting of platinum, rhodium, palladium, iridium, osmium, ruthenium, rhenium, gold and silver, or an alloy containing the metal. Electrode assembly. The catalyst concentration in at least one of the cathode catalyst layer and the anode catalyst layer increases stepwise or continuously from the electrolyte membrane side in the thickness direction, according to any one of claims 1 to 6 . Electrolyte membrane-electrode assembly. A fuel cell using the electrolyte membrane-electrode assembly according to any one of claims 1 to 7 . A vehicle equipped with the fuel cell according to claim 8 as a power source for driving a motor.