JP2011070926A - Electrolyte membrane-electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte membrane-electrode joint body having excellent durability and power generation performance, in particular, the electrolyte membrane-electrode joint body for a fuel cell. <P>SOLUTION: This electrolyte membrane-electrode joint body has: an electrolyte membrane; a cathode catalyst layer arranged in one side of the electrolyte membrane; a cathode side gas diffusion layer arranged in the cathode catalyst layer, and an anode catalyst layer; and an anode side gas diffusion layer arranged sequentially in the other side of the electrolyte membrane. An impurity trapping member is arranged between the cathode catalyst layer and the cathode side gas diffusion layer, between the anode catalyst layer and the anode side gas diffusion layer, in an inside of the cathode catalyst layer, or in an inside of the anode catalyst layer; the cathode catalyst layer and the anode catalyst layer contain a fluorine electrolyte; and the impurity trapping member contains a hydrocarbon electrolyte. <P>COPYRIGHT: (C)2011,JPO&INPIT

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.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide an electrolyte membrane-electrode assembly, particularly an electrolyte membrane-electrode assembly for fuel cells, which is excellent in durability and power generation performance.

  The present inventors have intensively studied to solve the above problems. As a result, it has been found that the above problem can be solved by disposing an impurity trap member containing a hydrocarbon electrolyte in the catalyst layer or between the catalyst layer and the gas diffusion layer. Based on the above findings, the present invention has been completed.

  That is, the above object is achieved by an electrolyte membrane-electrode assembly in which a hydrocarbon electrolyte-containing catalyst layer is disposed in the catalyst layer or between the catalyst layer and the gas diffusion layer.

  According to the present invention, contaminants such as impurities from the outside can be trapped in the electrolyte membrane without deteriorating the material transport performance. 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 the cross-sectional schematic which shows one Embodiment of arrangement | positioning of the impurity trap member in the electrolyte membrane-electrode assembly of this invention. FIG. 3 is a schematic cross-sectional view showing a typical arrangement of an impurity trap member in a catalyst layer in the electrolyte membrane-electrode assembly of the present invention. 1 is a schematic cross-sectional view of an MEA (1) in Example 1. FIG. 3 is a schematic cross-sectional view of MEA (2) of Example 2. FIG. 6 is a schematic cross-sectional view of MEA (3) of Example 3. FIG. 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. 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 provides an electrolyte membrane, a cathode catalyst layer disposed on one side of the electrolyte membrane, a cathode side gas diffusion layer disposed on the cathode catalyst layer, and the other side of the electrolyte membrane sequentially. An anode catalyst layer disposed in the anode catalyst layer, and an anode gas diffusion layer disposed in the anode catalyst layer, wherein the impurity trap member is disposed between the cathode catalyst layer and the cathode gas diffusion layer, Between the anode catalyst layer and the anode side gas diffusion layer, disposed in the cathode catalyst layer or in the anode catalyst layer, the cathode catalyst layer and the anode catalyst layer include a fluorine-based electrolyte, The impurity trap member relates to an electrolyte membrane-electrode assembly including a hydrocarbon electrolyte.

  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.

  Further, as described above, in the fuel cell, the fuel gas containing hydrogen on the anode side and the gas containing oxygen on the cathode side are supplied via the respective gas diffusion layers. Here, the gas usually contains impurities such as various organic substances, inorganic substances and ions in addition to hydrogen or oxygen. For this reason, when the gas is supplied to the fuel cell, these impurities are mixed into the MEA (especially the catalyst layer) from the outside to inhibit the cell reaction in each catalyst layer, and the power generation performance of the fuel cell. And cause a decrease in durability.

  However, as described above, since the cell reaction proceeds in the catalyst layer, suppressing or preventing the deterioration of the catalyst layer or the mixing of impurities into the catalyst layer is in terms of the durability and power generation performance of the fuel cell. Very important. For this reason, development of the technique which suppresses deterioration of a catalyst and mixing of an impurity is strongly desired.

  The present invention is characterized in that an impurity trap member including a hydrocarbon electrolyte is disposed in the catalyst layer or between the catalyst layer and the gas diffusion layer, and the cathode catalyst layer and the anode catalyst layer include a fluorine-based electrolyte. And Here, when the impurity trap member is disposed in the catalyst layer, the catalyst eluted in the catalyst layer under the generation of the duty cycle can be trapped by the impurity trap member. For this reason, with such an arrangement, it is possible to effectively suppress and prevent the catalytic metal from being ionized and eluted into the electrolyte membrane. In addition, when an impurity trap member is present in the catalyst layer, the trapped catalyst is retained in the catalyst layer, so that the ionized and eluted catalyst is reused as a catalyst in the catalyst layer. sell.

  On the other hand, when the impurity trap member is disposed between the catalyst layer and the gas diffusion layer, contaminants (impurities) such as organic substances, inorganic substances, and ions mixed from the gas diffusion layer side can be trapped in the impurity trap member. With such an arrangement, it is possible to effectively suppress and prevent the impurities from being mixed into the catalyst layer. In addition to the above, the cathode catalyst layer and the anode catalyst layer include a fluorine-based electrolyte. By using such a catalyst layer having excellent proton conductivity, heat resistance, and chemical stability, the MEA of the present invention can exhibit high power generation performance.

  That is, according to the present invention, the elution of the catalyst to the electrolyte membrane can be suppressed / prevented even at the occurrence of a duty cycle, and at the same time, the catalyst eluted in the catalyst layer can be effectively utilized in the catalyst layer. In addition, it is possible to suppress / prevent contamination of impurities such as organic substances, inorganic substances, and ions mixed from the gas diffusion layer side into the catalyst layer. 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 automobile applications 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, the impurity trapping member is (i) between the cathode catalyst layer 120c and the cathode side gas diffusion layer 140c, (ii) between the anode catalyst layer 120a and the anode side gas diffusion layer 140a, (iii) It is disposed in the cathode catalyst layer 120c or (iv) in the anode catalyst layer 120a. The MEA of the present invention only needs to satisfy at least one of the above (i) to (iv). Considering the ease of ionization of the catalyst (hence, elution / precipitation problems), the influence of impurities mixed from the GDL side, etc., an impurity trap member is disposed at least on the cathode catalyst layer side, that is, (i) or (iii) ) Is preferable. As a result, the elution / precipitation of the catalyst in the cathode catalyst layer at a high potential can be effectively suppressed / prevented, and the influence when impurities are mixed is small. However, in the MEA according to the present invention, only the anode catalyst layer side may have the above arrangement structure (ii) or (iv), and both the cathode catalyst layer and the anode catalyst layer may have the above (i) to (i) It may have any combination of the arrangement structures of (iv).

  Here, the arrangement form of the impurity trap member is not particularly limited as long as any one of the above (i) to (iv) is satisfied. For example, the impurity trap member may exist in a layer state between the catalyst layer and the GDL or in the catalyst layer. Alternatively, a plurality of impurity trap members may be present between the catalyst layer and the GDL or dispersed in the catalyst layer. That is, the impurity trapping member according to the present invention is preferably arranged in the form of a single layer extending along the surface direction or in a dispersed form.

  Among these, in the case where the impurity trap member is arranged in the form of a single layer extending along the surface direction, it is applied in the above (i) to (iv). For example, in the cases (i) and (ii) above, as shown in FIG. 3A, the impurity trap member 150 is disposed between the catalyst layer 120 and the gas diffusion layer 140. According to such an arrangement, impurities such as organic substances, inorganic substances, and ions mixed from the gas diffusion layer side can be trapped by the impurity trap member 15. For this reason, with such an arrangement, the amount of impurities mixed into the MEA from the outside can be reduced, and mixing of impurities that adversely affect the catalyst layer into the catalyst layer can be effectively suppressed / prevented. In the cases (iii) and (iv), the impurity trap member 150 is disposed in the catalyst layer 120 as shown in FIG. 3B. According to such an arrangement, even if the catalyst elutes in the catalyst layer under the occurrence of a duty cycle, it can be trapped by the impurity trap member. Also, ions are prevented from moving in the hydrocarbon. Here, since the impurity trap member 150 contains the HC electrolyte, the eluted catalyst (particularly, platinum ions) is efficiently held in the impurity trap member. For this reason, elution and precipitation (particularly, Pt band formation) of the catalyst in the electrolyte membrane can be suppressed / prevented. Moreover, according to the said form, the trapped catalyst is hold | maintained in a catalyst layer. For this reason, the eluted catalyst can be reused as a catalyst in the catalyst layer.

  Further, the dispersion form of the impurity trap member when the impurity trap member is arranged in a dispersed form is not particularly limited. Specifically, as shown in FIG. 4A, the impurity trap member is dispersed and arranged in a form extending in the thickness direction in the catalyst layer; as shown in FIG. 4B, the impurity trap member is a catalyst. Examples include a form in which the impurity trap members are dispersed and arranged in a lump form as shown in FIG. 4C, and the like. Among these, in the case of FIGS. 4A to 4C, the impurity trap member traps the catalyst eluted in the catalyst layer under the occurrence of the duty cycle and hardly disturbs the gas flow from the GDL. For this reason, according to the said form, the elution and precipitation (especially Pt band formation) of the catalyst in electrolyte membrane can be suppressed and prevented, maintaining gas permeability.

  That is, the impurity trap member according to the present invention is disposed in the form of a single layer extending along the surface direction of the electrolyte membrane between (a) the catalyst layer and the gas diffusion layer; (b) the catalyst Arranged in the form of a single layer extending along the surface direction of the electrolyte membrane in the layer; (c) arranged in a dispersed manner in the thickness direction in the catalyst layer; or ( d) It is preferable to disperse and arrange in a block shape or a flat plate shape in the catalyst layer. Said (a)-(d) may be each independent form, or 2 or more types may be combined suitably.

  Further, the method for forming the impurity trap member according to the present invention is not particularly limited, and is appropriately selected depending on the arrangement form of the impurity trap member. For example, in the case of the above (a), the ink containing the HC electrolyte is directly applied on the catalyst layer or the gas diffusion layer by a known method such as a direct application method (for example, a spray method) or a transfer method, or It is desirable to produce the substrate by applying it indirectly on a transfer mount. In the case of (b), it is desirable that the catalyst layer, the impurity trap member (layer), and the catalyst layer are sequentially produced by a known method such as a direct coating method (for example, spray method) or a transfer method. . Note that only one impurity trap member (layer) may be formed between the catalyst layers, or two or more layers may be formed between the catalyst layers. In the case of the above (c), a plate having the same shape as the member is placed where the impurity trap member is to be placed, and the catalyst is obtained by a known method such as a direct coating method (for example, spray method) or a transfer method. Form a layer. Next, a method of removing the plate and injecting an ink containing an HC electrolyte into the space where the plate is present to form an impurity trap member is preferable. Furthermore, in the case of the above (d), the impurity trap member is formed into a predetermined shape (block shape or flat plate shape). A method of mixing this with a catalyst ink to form a catalyst layer can be used. Alternatively, the ink containing the HC electrolyte is stirred and mixed with the catalyst, and then the F electrolyte is stirred and mixed. The catalyst layer having the structure (d) is formed from this mixture by a known method such as a direct coating method (for example, spray method) or a transfer method. Here, a catalyst coated with the HC electrolyte is obtained by stirring and mixing the ink containing the HC electrolyte with the catalyst. Next, the catalyst coated with the HC electrolyte is stirred and mixed with the F electrolyte to obtain a catalyst in which the HC electrolyte coating layer is further coated with the F electrolyte. By having such a structure, the elution of the catalyst under the occurrence of the duty cycle can be effectively suppressed / prevented by the HC electrolyte coating layer.

  In addition, as above-mentioned, this invention has a structure in any one of said (i)-(iv), and description of each catalyst layer in the case of having the said 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 impurity trap member containing the HC-based electrolyte is simply referred to as “impurity trap member”, and the catalyst layer including the F-based electrolyte is simply referred to as “catalyst layer”. Further, in this specification, the “impurity trap member” essentially includes an HC electrolyte, and may include an electrode catalyst if necessary. Further, the “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.

  In the present invention, in addition to the above (i) to (iv), an impurity trap member may be further disposed on the electrolyte membrane. According to this form, the eluted catalyst is trapped immediately before the electrolyte membrane. For this reason, in the MEA of the present invention, elution of the catalyst into the electrolyte membrane can be effectively suppressed / prevented. Therefore, according to the said form, even if it is under generation | occurrence | production of a duty cycle, the elution to the electrolyte membrane of a catalyst can be suppressed and prevented. Therefore, the catalyst layer according to the embodiment can maintain high catalytic activity for a longer period. 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. When the impurity trap member is disposed on the electrolyte membrane, the impurity trap member may be a single layer or a laminate of two or more. In the latter case, each impurity trap member may be the same member or different members (for example, a member containing a catalyst, a member not containing a catalyst, and two or more members made of different HC electrolytes). May be.

  In the present invention, the existence form of the HC electrolyte is not particularly limited, and may be present in the impurity trap member uniformly or non-uniformly. Preferably, the HC electrolyte concentration in the impurity trap member 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 GDL side is gradually increased; either the electrolyte membrane side or the GDL side is gradually increased. Any form may be used, such as lowering the HC-based electrolyte concentration in the impurity trap member. For example, when the impurity trap member is arranged in the form of a single layer extending along the surface direction of the electrolyte membrane between the catalyst layer and the GDL [above (a)], the HC-based electrolyte concentration on the GDL side is The thickness is preferably higher than the catalyst layer side in the thickness direction. Thereby, mixing of impurities from the outside can be effectively suppressed / prevented. Here, the HC electrolyte concentration can change stepwise or continuously. In the impurity trap member, the gradient of the HC electrolyte concentration is not particularly limited. Considering the effect of suppressing / preventing impurity contamination, the ratio of the high side (GDL side) to the low side (catalyst layer side) of the HC-based electrolyte concentration (wt%) is preferably 1.5 to 100 times, more preferably Is 3 to 20 times. With such a ratio, the impurity trap member can sufficiently trap external impurities (organic matter, inorganic matter, ions, etc.), and the penetration of the catalyst into the electrolyte membrane can be sufficiently suppressed and 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.

  Further, when the impurity trap member is disposed in the catalyst layer [above (b) to (d)], the HC electrolyte concentration on the electrolyte membrane side is preferably higher than that on the GDL side in the thickness direction. . Thus, by increasing the concentration of the HC electrolyte 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. With the above structure, the catalyst (particularly noble ions) eluted from the catalyst layer by the duty cycle can be trapped more efficiently by the impurity trap member. Moreover, the catalyst trapped here can prevent the movement in the impurity trap member more. Therefore, according to this embodiment, the catalyst can be effectively utilized again as a catalyst in the impurity trap member while suppressing / preventing the elution / precipitation (particularly, Pt band formation) of the catalyst in the electrolyte membrane. Here, the HC electrolyte concentration can change stepwise or continuously. In the impurity trap member, the gradient of the HC electrolyte concentration is not particularly limited. Considering the effect of suppressing / preventing contamination of impurities and the trapping property (ion blocking property) of the eluted catalyst, the ratio of the high side (electrolyte membrane side) to the low side (GDL side) of the HC electrolyte concentration (wt%) However, it is preferably 1.5 to 100 times, more preferably 3 to 20 times. With such a ratio, the eluted catalyst (particularly noble ions) can be sufficiently trapped by the impurity trap member, and the penetration of the catalyst into the electrolyte membrane can be sufficiently suppressed and 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.

  Thus, the formation method of the impurity trap member from which HC system electrolyte concentration differs is not specifically limited. For example, it can be achieved by preparing a predetermined number of electrolyte solutions having different HC-based electrolyte concentrations and sequentially laminating impurity trap members using these electrolyte solutions so as to obtain a desired concentration gradient. Alternatively, by using the electrolyte solutions having different concentrations, an impurity trap member having a predetermined shape (bulk shape or flat plate shape) is formed, and this is arranged so as to have a desired concentration gradient in the catalyst layer. Can be achieved. Here, the ion blocking property can be controlled by changing the concentration of the HC electrolyte in the electrolyte solution, and the ion blocking property can be changed in stages by repeatedly applying different ion blocking catalyst layers. Is possible. By changing the ion blocking property in this way, impurities (especially noble ions) eluted from the catalyst layer due to external impurities and duty cycles can be efficiently trapped by the impurity trap member. Further, the impurities and catalyst trapped here are prevented from moving within the impurity trap member. Especially by trapping the catalyst, it can be effectively used again as a catalyst in the impurity trap member, and the elution / precipitation of the catalyst (especially, Pt band formation) in the electrolyte membrane can be suppressed, and the elution resistance of the catalyst (especially platinum) and high power generation Both sexes can be achieved.

  In the present invention, the 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. Here, the presence state of the F-based electrolyte is not particularly limited, and may be present in the catalyst layer either uniformly or non-uniformly. Moreover, when it exists nonuniformly, the F type electrolyte density | concentration in a catalyst layer may change in steps or continuously with respect to the thickness direction. Further, the method of changing is not particularly limited, and either the electrolyte membrane side or the catalyst layer side is gradually increased; the F-based electrolyte concentration in each catalyst layer is arbitrarily changed; It may be a form. The method for forming the catalyst layers 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 catalyst layers using these catalyst inks so as to obtain a desired concentration gradient.

  In the present invention, the volume ratio between the impurity trap member and the catalyst layer is such that the impurities trapped from the outside and the catalyst (particularly noble ions) eluted from the catalyst layer can be efficiently trapped by the impurity trap member. There is no particular limitation. In the present specification, the “volume ratio of the impurity trap member to the catalyst layer” means the volume ratio of the catalyst layer to the impurity trap member, that is, the ratio of the volume of the catalyst layer to the volume of the impurity trap member. Preferably, the volume ratio of the catalyst layer to the impurity trap member is 0.01 to 10, more preferably 2 to 5. Within such a range, the catalyst (especially noble ions) eluted in the catalyst layer can be efficiently trapped by the impurity trap member, and the eluted catalyst can be effectively used again in the impurity trap member. it can.

  In the present invention, the state of the interface between the impurity trap member and the catalyst layer is not particularly limited. For example, (1) a form in which the interface between the impurity trap member and the catalyst layer is clearly divided and formed; (2) the interface between the impurity trap member and the catalyst layer is not clear, and the HC system is formed between the impurity trap member and the catalyst layer. There is a form in which an intermediate layer in which the concentration of each electrolyte mixed with the electrolyte and the F-based electrolyte is inclined exists.

  According to the form of (1) above, in the MEA thickness (cross-section) direction, the ion barrier property is clearly different at the interface. Moreover, although the form of said (1) may be obtained by any methods, for example, after forming an impurity trap member on GDL first, it can achieve by forming a catalyst layer. Alternatively, it can also be achieved by forming an impurity trap member after forming a catalyst layer on a transfer mount. At this time, the method for forming the impurity trapping member and the catalyst layer is not particularly limited, but it is desirable that the impurity trapping member and the catalyst layer be produced stepwise by a known method such as a direct coating method (for example, spray method) or a transfer method. By clearly changing the ion blocking property in this way, impurities mixed from the outside and catalyst (particularly noble ions) eluted from the catalyst layer by the duty cycle can be efficiently trapped by the impurity trap member. Further, the impurities and catalyst trapped here are prevented from moving within the impurity trap member. According to this embodiment, the eluted catalyst can be effectively used again as a catalyst in the impurity trap member, and elution / precipitation (particularly, Pt band formation) of the catalyst in the 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.

  Further, according to the form (2), for example, by changing the ion blocking property with a gradient in the thickness direction, it is possible to disperse impurities from the outside and elution / precipitation of the catalyst. In the latter case, elution / precipitation of the catalyst 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 impurity trapping member. For this reason, according to the said form, it can utilize effectively as a catalyst again also in an impurity trap member and an intermediate | middle layer, and the elution and precipitation (especially Pt band formation) of the catalyst in an electrolyte membrane can be suppressed. The form (2) may be obtained by any method. For example, it can be achieved by applying the catalyst ink for forming the catalyst layer and drying it in a wet-on-wet state without applying (drying) the layer after applying the electrolyte ink for forming the impurity trapping member [ Form (2-1)]. The formation method of the impurity trap member and the catalyst layer is not particularly limited, but it is desirable to produce the impurity trap member and the catalyst layer stepwise by a known method such as a direct coating method (for example, a spray method) or a transfer method. According to this embodiment, since the ion blocking property continuously changes (inclines), it can be used again as a catalyst in the catalyst layer. In addition, the catalyst (particularly Pt ions) trapped by the HC electrolyte is prevented from moving in the impurity trap member. 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. In addition, it is possible to effectively suppress / prevent contamination from external impurities. Here, the concentrations of the HC-based electrolyte and the F-based electrolyte in the intermediate layer are not particularly limited, but preferably have a concentration gradient similar to the above. Thereby, mixing of impurities such as organic substances, inorganic substances and ions from the outside and elution / precipitation of the catalyst on the film can be more effectively suppressed / prevented, and both elution resistance of the catalyst (particularly platinum) and high power generation can be achieved.

  Alternatively, in the form of (2), an impurity trap member is formed, and a catalyst ink in which HC and F electrolytes are mixed at an appropriate ratio is applied and dried to form an intermediate layer, and then formed on the intermediate layer. It can also be achieved by forming a catalyst layer [form (2-2)]. Here, the formation method of the impurity trap member, the catalyst layer, and the intermediate layer is not particularly limited, but it is desirable to produce the impurity trap member stepwise by a known method such as a direct application method (for example, a spray method) or a transfer method.

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

  According to the form of (2), it is possible to disperse impurities from the outside and precipitation of platinum by changing (inclining) the ion blocking property in a stepwise (multistage) manner. In the latter case, the catalyst (particularly Pt ions) trapped by the HC electrolyte is prevented from moving within the impurity trap member. 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 impurity trap member and the 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 gradually decreases from the electrolyte membrane side to the catalyst layer side, 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 impurity trap member is decreased and the catalyst concentration in the catalyst layer is increased; the catalyst concentration in the impurity trap member is increased stepwise or continuously from the electrolyte membrane side in the thickness direction. Any method may be used, such as increasing the catalyst concentration in the 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 impurity trap member and increase the catalyst concentration in the 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 impurity trap member can be used in the same manner. With such a configuration, a large number of catalysts can be arranged on the catalyst layer (especially on the catalyst layer side) with good reaction efficiency, so that an MEA with high reaction efficiency is 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 (wt%) on the 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 3 times. 20 times. 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 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.

(Impurity trap member)
In the MEA of the present invention, the impurity trap member is disposed at a predetermined position as described above 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 and copolymers 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.

  Further, the impurity trap member may include an electrode catalyst if necessary. By including the electrode catalyst in this way, catalytic activity can be imparted to the impurity trap member, which is preferable in terms of power generation performance and the like. Here, the content of the electrode catalyst in the impurity trap member is not particularly limited, but is preferably 10 to 60% by mass in the impurity trap member (in terms of solid content).

  The method for forming the impurity trapping member 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. Here, when a plurality of impurity trap members are formed, each impurity trap member may be formed by the same method or conditions, or by different methods and conditions.

  The thickness of the impurity trap member can be appropriately determined in consideration of the characteristics of the obtained fuel cell, and is preferably such a thickness that the volume ratio with the catalyst layer is as described above. For example, as shown in FIGS. 3A and 3B, in the case of the form of a single layer, the thickness of the impurity trap member is usually preferably 0.001 to 50 μm, more preferably 0.003 to 20 μm, particularly Preferably it is 0.01-10 micrometers. Further, as shown in FIG. 4A, when dispersed in a form extending in the thickness direction, the size of the impurity trap member is substantially the same as the length of the catalyst layer in the thickness direction, The length in the surface direction is usually preferably 0.001 to 50 μm, more preferably 0.01 to 10 μm. Furthermore, as shown in FIGS. 4B and 4C, when dispersed in a lump or flat plate, the size of the impurity trapping member is preferably 0.001 to 50 μm × 0.001 to 50 μm, more preferably 0.00. It is 01-10 micrometers x 0.01-10 micrometers. If it is such a range, mixing of the impurity from the outside can be suppressed and prevented effectively. Also, within this range, the catalyst (especially noble metal ions) eluted in the catalyst layer by the load cycle can be sufficiently trapped, and can be effectively used again as a catalyst, and the catalyst is eluted and deposited in the electrolyte membrane ( In particular, Pt band formation) can be suppressed.

(Catalyst layer)
The catalyst layer according to the present invention is disposed on the electrolyte membrane and includes an F-based electrolyte. Here, the catalyst layer includes an electrode catalyst in which a catalyst component is supported on a conductive carrier.

  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 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.

  The cathode catalyst layer / anode catalyst layer (hereinafter also simply referred to as “catalyst layer”) of the present invention contains an F-based polymer electrolyte in addition to the electrode catalyst. The F-based electrolyte used in the present invention is not particularly limited and a known fluorine-based electrolyte can be used, but it has at least proton conductivity. Specifically, as the fluorine-based electrolyte having a proton dissociable functional group constituting the fluorine-based electrolyte, 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 polymer, polytrifluorostyrene sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylenetetrafluoroethylene-g-styrene sulfonic acid -Based polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride-perfluorocarbon sulfonic acid polymer, ion exchange resin manufactured by Dow Chemical Company, ethylene-tetrafluoroethylene copolymer, trifluorostyrene A resin to Rimmer are mentioned as suitable examples. These fluorine-based 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 catalyst layer contains the electrode catalyst. Here, the content of the electrode catalyst in the 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 catalyst layer is not particularly limited, and 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 catalyst layer can be appropriately determined in consideration of the characteristics of the obtained fuel cell, and is preferably such a thickness that the volume ratio with the impurity trap member as described above is obtained. Usually, the thickness of the catalyst layer is preferably 0.05 to 50 μm, more preferably 0.1 to 30 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 impurity trap member and the 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 impurity trap member and the 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 above-described electrode catalyst, F-based polymer electrolyte and solvent, and this is applied onto the electrolyte membrane to form a catalyst layer. Next, in the same manner, an HC polymer electrolyte and a solvent as described above are mixed to prepare an electrolyte ink (2), which is applied onto the catalyst layer formed above, whereby an impurity trap member. Form. 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 an electrolyte membrane, a catalyst layer, and an impurity trap member can be obtained.

  A preferred embodiment of the transfer method is as follows. First, an impurity trap member is formed by applying an electrolyte ink (2 ') containing the HC polymer electrolyte and solvent as described above to a transfer mount or a gas diffusion layer. Next, in the same manner, a catalyst ink (1 ′) is prepared by mixing the above-described electrode catalyst, F-based polymer electrolyte and solvent, and this is applied onto the impurity trap member formed above. To form a catalyst layer. 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 onto a predetermined substrate (electrolyte film, transfer mount, impurity trap member, catalyst layer) such that the thickness after drying becomes the predetermined thickness as described above. 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.

  As described above, the electrolyte membrane-electrode assembly of the present invention and the electrolyte membrane-electrode assembly produced by the method of the present invention have excellent durability and high power generation performance. Therefore, by using such an electrolyte membrane-electrode assembly, a fuel cell excellent in durability and power generation performance can be provided.

(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.

Example 1
1. Preparation of catalyst ink for forming catalyst layer 20 mg of platinum catalyst, 19 ml of ultrapure water, 6 ml of isopropyl alcohol, and 100 μl of 0.5 wt% Nafion (registered trademark) dispersion solution (DuPont Co., Ltd., DE2020CS) as F-based electrolyte In addition, a mixed solution was prepared. 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 Electrolyte Ink for Impurity Trap Member Formation Sulfated polyethersulfone (s-PES) as an HC-based electrolyte was mixed with isopropyl alcohol so as to have a concentration of 0.5 wt% to prepare a mixed solution. The obtained mixed liquid was subjected to ultrasonic treatment for 30 minutes to obtain an electrolyte ink (2). In addition, 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 (in terms of polyethylene glycol (PEG)).

3. Formation of catalyst layer (1) 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 and dried at 60 ° C. for 10 minutes to obtain a catalyst layer. (1) was formed.

4). Formation of impurity trapping member 2. 2 μl of the electrolyte ink (2) prepared in step 3 above was added. The impurity trap member was formed on the catalyst layer (1) by applying the solution on the catalyst layer (1) formed in step 1 using a micropipette and drying at 60 ° C. for 10 minutes.

5). Formation of catalyst layer (2) 2 μl of the catalyst ink (1) prepared in step 4 above was added. It was applied on the impurity trapping member formed by using a micropipette and dried at 60 ° C. for 10 minutes to form a catalyst layer (2) on the impurity trapping member to obtain a laminate (1).

Thereby, the total amount of Pt supported in the catalyst layer is 0.35 mg / cm ² , the average thickness of the catalyst layer (1) is about 0.1 μm, and the average thickness of the catalyst layer (2) is about It was 0.1 μm. Moreover, the average thickness of the impurity trap member formed between the catalyst layers (1) and (2) was 0.02 μm. The volume ratio of the catalyst layer (total) to the impurity trap member is 5.

  As shown in FIG. 5, the laminate (1) had a structure in which a glassy carbon electrode, a catalyst layer (1), an impurity trap member, and a catalyst layer (2) were sequentially formed.

Example 2
1. Formation of catalyst layer (1) 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, Layer (1) was formed.

2. Formation of impurity trap member (1) Example 1 above. 10 μl of the electrolyte ink (2) prepared in the above 1. The impurity trap member (1) was formed on the catalyst layer (1) by applying it on the catalyst layer (1) formed in Step 1 using a micropipette and drying at 60 ° C. for 10 minutes.

3. Formation of catalyst layer (2) Example 1 above. 10 μl of the catalyst ink (1) prepared in (1) above was added to the above 2. The catalyst layer (2) was formed on the impurity trapping member (1) by applying the micropipette on the impurity trapping member formed in (1) above and drying at 60 ° C. for 10 minutes.

4). Formation of impurity trap member (2) Example 1 above. 10 μl of the electrolyte ink (2) prepared in (3) above was added. The catalyst layer (2) formed in (1) was applied using a micropipette and dried at 60 ° C. for 10 minutes to form an impurity trap member (2) on the catalyst layer (2). Got.

Thereby, the total amount of Pt supported in the catalyst layer is 0.35 mg / cm ² , the average thickness of the catalyst layer (1) is 0.1 μm, and the average thickness of the catalyst layer (2) is 0.00. It was 1 μm. Moreover, the average thickness of the impurity trap member (1) was 0.01 μm, and the average thickness of the impurity trap member (2) was 0.01 μm. The volume ratio of the catalyst layer (total) to the impurity trap members (total) is 5.

  As shown in FIG. 6, this laminate (2) has a structure in which a glassy carbon electrode, a catalyst layer (1), an impurity trap member (1), a catalyst layer (2), and an impurity trap member (2) are sequentially formed. Met.

Example 3
1. Preparation of catalyst ink for forming catalyst layer 20 mg of palladium catalyst, 19 ml of ultrapure water, 6 ml of isopropyl alcohol, and 100 μl of 0.5 wt% Nafion (registered trademark) dispersion solution (DuPont Co., Ltd., DE521CS) as F-based electrolyte In addition, a mixed solution was prepared. 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 Electrolyte Ink for Impurity Trap Member Formation 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 an electrolyte ink (4). The palladium catalyst is the same as in the above 1. Is the same. In addition, the s-PES solution was used in Example 1. It is the same as the s-PES solution used in 1.

3. Formation of catalyst layer (1) 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, dried at 60 ° C. for 10 minutes, Layer (1) was formed.

4). Formation of impurity trapping member 2. 2 μl of the electrolyte ink (4) prepared in step 3 above was added. The impurity trap member was formed on the catalyst layer (1) by applying the solution on the catalyst layer (1) formed in step 1 using a micropipette and drying at 60 ° C. for 10 minutes.

5). Formation of catalyst layer (2) 2 μl of the catalyst ink (3) prepared in (4) above was added. It was applied on the impurity trapping member formed by using a micropipette and dried at 60 ° C. for 10 minutes to form a catalyst layer (2) on the impurity trapping member to obtain a laminate (3).

Thereby, the total amount of Pt supported in the catalyst layer is 0.35 mg / cm ² , the average thickness of the catalyst layer (1) is 0.1 μm, and the average thickness of the catalyst layer (2) is 0.00. It was 1 μm. The average thickness of the impurity trap member formed between the catalyst layers (1) and (2) is 0.04.
It was μm. The volume ratio of the catalyst layer (total) to the impurity trap member is 5.

  As shown in FIG. 7, the laminate (3) had a structure in which a glassy carbon electrode, a catalyst layer (1), an impurity trap member, and a catalyst layer (2) were sequentially formed.

Example 4
1. Formation of catalyst layer (1) Example 3 above. 2 μl of the catalyst ink (3) prepared in ( ¹ ) above 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. Layer (1) was formed.

2. Formation of impurity trap member (1) Example 3 above. 2 μl of the electrolyte ink (4) prepared in 1. The impurity trap member (1) was formed on the catalyst layer (1) by applying it on the catalyst layer (1) formed in Step 1 using a micropipette and drying at 60 ° C. for 10 minutes.

3. Formation of catalyst layer (2) Example 3 above. 2 μl of the catalyst ink (3) prepared in (2) above was added. The catalyst layer (2) was formed on the impurity trapping member (1) by applying the micropipette on the impurity trapping member formed in (1) above and drying at 60 ° C. for 10 minutes.

4). Formation of impurity trap member (2) Example 3 above. 2 μl of the electrolyte ink (4) prepared in step 3 above was added. The catalyst layer (2) formed in Step 1 was applied using a micropipette and dried at 60 ° C. for 10 minutes to form an impurity trap member (2) on the catalyst layer (2). Got.

Thereby, the total amount of Pt supported in the catalyst layer is 0.35 mg / cm ² , the average thickness of the catalyst layer (1) is 0.1 μm, and the average thickness of the catalyst layer (2) is 0.00. It was 1 μm. Moreover, the average thickness of the impurity trap member (1) was 0.004 μm, and the average thickness of the impurity trap member (2) was 0.004 μm. The volume ratio of the catalyst layer (total) to the impurity trap members (total) is 5.

  As shown in FIG. 8, the laminate (4) has a structure in which a glassy carbon electrode, a catalyst layer (1), an impurity trap member (1), a catalyst layer (2), and an impurity trap member (2) are sequentially formed. Met.

Example 5
3.5 parts by weight of sulfonated polyethersulfone (s-PES) (made in-house) as HC electrolyte was dissolved in 72.4 parts of 1-propanol and 24.1 parts of ion-exchanged water. The HC electrolyte solution was obtained. 17 parts of this solution, 55.5 parts of 1-propanol, 18.0 parts of ion-exchanged water, and 5.5 parts of 50% platinum-supported carbon were stirred and mixed in a media mill for 3 hours. Next, 4.0 parts of a 0.5 wt% Nafion (registered trademark) dispersion solution (DuPont Co., Ltd., DE2020CS) as an F-based electrolyte was added to this mixed liquid, and stirred and mixed to obtain catalyst ink (5). Got. By this operation, a catalyst is obtained in which the catalyst surface is sequentially coated with an HC electrolyte and an F electrolyte. In addition, platinum-supported carbon (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., TEC10E50E, platinum content 46% by mass) was used as the platinum catalyst.

10 μl of the catalyst ink (5) thus prepared 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. Thus, a laminate (5) was obtained.

In the laminate (5) thus obtained, a massive impurity trap member (average size: 0.1 μm × 0.5 μm) in which the catalyst surface is sequentially coated with the HC electrolyte and the F electrolyte is the catalyst layer. Exist in a distributed manner. Further, the total amount of Pt supported in the catalyst layer was 0.35 mg / cm ² , and the average thickness of the catalyst layer was 0.1 μm. The volume ratio of the catalyst layer (total) to the impurity trap members (total) is 5.

Comparative Example 1
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 and dried at 60 ° C. for 10 minutes for comparison. A laminate (1) was produced. As a result, a catalyst layer having a Pt loading of 0.35 mg / cm ² and an average thickness of 0.1 μm was formed on the gas diffusion layer.

  As shown in FIG. 9, this comparative laminate (1) had a structure in which only the catalyst layer was formed on the glassy carbon electrode.

Comparative Example 2
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, dried at 60 ° C. for 10 minutes, and compared. A laminate (2) was produced. As a result, a catalyst layer having a Pd loading of 15 mg / 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 catalyst layer was formed on the glassy carbon electrode.

(Electrochemical evaluation test)
For the laminates (1) to (4) and the comparative laminates (1) to (2) prepared in Examples 1 to 4 and Comparative Examples 1 to 2, electrochemical characteristics were evaluated as follows. 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 laminates (1) to (4) and the comparative laminates (1) to (2) produced in Examples 1 to 4 and Comparative Examples 1 to 2 was evaluated as follows. That is, each sample (half-cell catalyst electrode layer) was massed before and after the 10,000 cycle test using a rectangular wave of 0.6 to 1.0 V, 3 s at 60 ° C. in 0.1 M HClO ₄ saturated with nitrogen. The initial ratio (%) of activity was determined, and the catalyst metal dissolution resistance was measured. The mass activity change rate was 95%.

  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 this electrode has a significantly lower initial mass activity ratio 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 (10)

An electrolyte membrane;
A cathode catalyst layer disposed on one side of the electrolyte membrane;
A cathode-side gas diffusion layer disposed in the cathode catalyst layer;
An anode catalyst layer sequentially disposed on the other side of the electrolyte membrane; and an anode gas diffusion layer disposed on the anode catalyst layer;
Have
An impurity trap member is disposed between the cathode catalyst layer and the cathode side gas diffusion layer, between the anode catalyst layer and the anode side gas diffusion layer, in the cathode catalyst layer, or in the anode catalyst layer. Placed in
The cathode catalyst layer and the anode catalyst layer include a fluorine-based electrolyte,
The impurity trap member is an electrolyte membrane-electrode assembly including a hydrocarbon electrolyte.   2. The electrolyte membrane-electrode assembly according to claim 1, wherein the impurity trap members are arranged in a single layer extending in a plane direction or in a dispersed form. The impurity trap member is:
(A) Arranged between the catalyst layer and the gas diffusion layer in the form of a single layer extending along the surface direction of the electrolyte membrane;
(B) disposed in the catalyst layer in the form of a single layer extending along the surface direction of the electrolyte membrane;
(C) Dispersed and disposed in a form extending in the thickness direction in the catalyst layer; or (d) Dispersed and disposed in a lump or plate in the catalyst layer.
The electrolyte membrane-electrode assembly according to claim 1 or 2, which is arranged in any form.   The electrolyte membrane-electrode assembly according to any one of claims 1 to 3, wherein an impurity trap member is further disposed on the electrolyte membrane.   The electrolyte membrane-electrode assembly according to any one of claims 1 to 4, wherein the hydrocarbon electrolyte contained in the impurity trap member is an aromatic electrolyte having a super strong acid group.   The electrolyte membrane according to any one of claims 1 to 5, wherein a volume ratio of the catalyst layer to the impurity trap member (= a ratio of a volume of the catalyst layer / a volume of the impurity trap member) is 0.01 to 10. An electrode assembly.   The electrolyte membrane-electrode assembly according to any one of claims 1 to 6, wherein the cathode catalyst layer and the anode catalyst layer contain a noble metal as a catalyst component.   The electrolyte membrane according to claim 7, 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.   A fuel cell comprising the electrolyte membrane-electrode assembly according to any one of claims 1 to 8.   A vehicle equipped with the fuel cell according to claim 9 as a power source for driving a motor.