Catalyst layer for electrochemical devices, film electrode assembly, electrochemical device, and method for manufacturing a catalyst layer for electrochemical devices.

Abstract

This invention provides a catalyst layer for electrochemical devices that offers excellent durability and is suitable for improving power generation efficiency. [Solution] The catalyst layer 100 of the present disclosure has a first main surface 101 to be positioned on the gas diffusion layer side of an electrochemical device and a second main surface 102 to be positioned on the electrolyte membrane side, and includes a conductive material 11, catalyst particles 12, a first ionomer 31 having a cyclic structure in its main chain, and a second ionomer 32 having a molecular structure different from that of the first ionomer 31. The portion including the first main surface 101 and located on the side of the first main surface 101 is defined as the first portion 101p, and the portion including the second main surface 102 and located on the side of the second main surface 102 is defined as the second portion 102p. The proportion of the mass of the first ionomer 31 contained in the first portion 101p is greater than the proportion of the mass of the second ionomer 32, and the proportion of the mass of the second ionomer 32 contained in the second portion 102p is greater than the proportion of the mass of the first ionomer 31.

Description

[Technical Field]

[0001] This disclosure relates to a catalyst layer for an electrochemical device, a film electrode assembly, an electrochemical device, and a method for manufacturing a catalyst layer for an electrochemical device. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a membrane electrode assembly, comprising the steps of sequentially laminating a first ionomer layer containing a first ionomer and a second ionomer layer containing a second ionomer having higher oxygen permeability than the first ionomer on a transfer film, and transferring the first ionomer layer and the second ionomer layer to an electrolyte membrane. According to the manufacturing method of Patent Document 1, the second ionomer layer containing the second ionomer with higher oxygen permeability is placed on the electrolyte membrane side.

[0003] Patent Document 2 discloses a method for producing a catalyst ink for fuel cell electrodes, comprising a catalyst, a solvent, a highly oxygen-permeable gel-like ionomer, and a solution of the ionomer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-134999 [Patent Document 2] Japanese Patent Publication No. 2023-34773 [Overview of the project] [Problems that the invention aims to solve]

[0005] The purpose of this disclosure is to provide a catalyst layer for electrochemical devices that is highly durable and suitable for improving power generation efficiency. [Means for solving the problem]

[0006] The catalyst layer for electrochemical devices in this disclosure is A catalyst layer having a first main surface to be positioned on the gas diffusion layer side and a second main surface to be positioned on the electrolyte membrane side in an electrochemical device, The material comprises a conductive material, catalyst particles supported on the conductive material, a first ionomer having a cyclic structure in its main chain, and a second ionomer having a molecular structure different from that of the first ionomer. When the portion including the first main surface and located on the side of the first main surface is defined as the first portion, and the portion including the second main surface and located on the side of the second main surface is defined as the second portion, The ratio of the mass of the first ionomer contained in the first portion to the total mass of the resin components contained in the first portion is greater than the ratio of the mass of the second ionomer contained in the first portion to the total mass of the resin components contained in the first portion. The ratio of the mass of the second ionomer contained in the second portion to the total mass of the resin components contained in the second portion is greater than the ratio of the mass of the first ionomer contained in the second portion to the total mass of the resin components contained in the second portion.

[0007] In another aspect, the film electrode junction in this disclosure is A-scatter, Cathode and, An electrolyte membrane disposed between the anode and the cathode, Equipped with, The cathode includes the catalyst layer for the electrochemical device described herein.

[0008] In another respect, the electrochemical devices in this disclosure are The present invention comprises the film electrode assembly described above.

[0009] In another aspect, the method for manufacturing a catalyst layer for an electrochemical device in this disclosure is: The first solution is prepared by dispersing a conductive material on which catalyst particles are supported and a first ionomer having a cyclic structure in its main chain in a first solvent, Dispersing the conductive material carrying the catalyst particles and a second ionomer having a molecular structure different from the first ionomer in a second solvent to prepare a second solution; Coating the second solution on an electrolyte membrane to form a second coated membrane; Removing the second solvent from the second coated membrane to produce a second layer; Coating the first solution on the second layer to form a first coated membrane; Removing the first solvent from the first coated membrane to produce a first layer; including.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a catalyst layer for an electrochemical device that is excellent in durability and suitable for improving power generation efficiency.

Brief Description of the Drawings

[0011] [Figure 1] Schematic cross-sectional view showing an example of a catalyst layer in Embodiment 1 [Figure 2A] Schematic cross-sectional view showing an example of a conductive material carrying catalyst particles and a first ionomer that may be included in a first portion of the catalyst layer [Figure 2B] Schematic cross-sectional view showing an example of a conductive material carrying catalyst particles and a second ionomer that may be included in a second portion of the catalyst layer [Figure 3] Flowchart showing an example of a method for manufacturing a catalyst layer in Embodiment 1 [Figure 4A] Schematic cross-sectional view of a membrane electrode assembly in Embodiment 2 [Figure 4B] Partial enlarged view of FIG. 4A [Figure 5] Schematic cross-sectional view of an electrochemical device in Embodiment 2

Modes for Carrying Out the Invention

[0012] (Findings etc. on which the present disclosure is based) For the catalyst to be effectively utilized in the cathode catalyst layer of an electrochemical device, it is important that a three-phase interface is formed in the cathode catalyst layer. Conventionally, it was recognized that uniformly coating the catalyst-supported carrier with an ionomer was effective in forming a three-phase interface in the cathode catalyst layer from the viewpoint of water retention and drainage. The three-phase interface is the interface between the carrier, the catalyst, and the ionomer. At the three-phase interface, protons (H) + ) and electrons (e - ) can move. However, in recent years it has become clear that catalysts can be poisoned and degraded by ionomers. Specifically, catalysts can be poisoned by functional groups such as sulfonic acid groups on ionomers, in particular functional groups containing sulfur atoms. At the time the present inventors conceived of this disclosure, contact between ionomers and catalyst particles was suppressed by supporting catalyst particles inside the pores of a porous conductive material.

[0013] Under these circumstances, the inventors found that ionomers block the pores of porous conductive materials, preventing gases such as protons and oxygen from sufficiently diffusing into catalyst particles located inside the pores of the conductive material. If gases such as protons and oxygen do not sufficiently diffuse into the catalyst particles, the catalyst particles located inside the pores of the conductive material cannot be fully utilized. On the other hand, if the amount of ionomer coating the conductive material is reduced to suppress pore blockage by the ionomer, the ionomer becomes discontinuous in the cathode catalyst layer, and as a result, the proton diffusion resistance of the film electrode assembly increases.

[0014] Therefore, the inventors focused on the gas permeability of ionomers. Ionomers with high gas permeability do not easily inhibit the diffusion of gases such as oxygen into the pores, even if they block the pores of the conductive material. However, ionomers with high gas permeability tend to have lower adsorption capacity to catalyst particles than ionomers with low gas permeability. When a ionomer with high gas permeability is used as the ionomer, the ionomer does not easily adsorb to the catalyst particles in the catalyst ink used to form the catalyst layer, making the entangled parts of the polymer chains prone to breakage. Therefore, when a catalyst layer is made on an electrolyte membrane using such a catalyst ink, cracks may occur in the catalyst layer, posing a problem in terms of durability. This is because the electrolyte membrane, which was swollen when the catalyst ink was applied, shrinks as it dries, generating stress. Consequently, it is difficult to realize a catalyst layer with high power generation efficiency by increasing the basis weight of the catalyst particles.

[0015] Based on these findings, the present inventors have arrived at the subject matter of this disclosure in order to improve power generation efficiency while ensuring the durability of the catalyst layer, even while using an ionomer with high gas permeability.

[0016] This disclosure provides a catalyst layer for electrochemical devices that is highly durable and suitable for improving power generation efficiency.

[0017] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art.

[0018] The attached drawings and the following description are provided to enable the parties to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0019] (Embodiment 1) Embodiment 1 will be described below with reference to Figures 1 to 3.

[0020] [1-1. Structure] Figure 1 is a schematic cross-sectional view showing an example of a catalyst layer 100 for an electrochemical device in Embodiment 1. The catalyst layer 100 has a first main surface 101 and a second main surface 102 opposite to the first main surface 101. The first main surface 101 is the surface that should be positioned on the gas diffusion layer side in the electrochemical device. The second main surface 102 is the surface that should be positioned on the electrolyte membrane side in the electrochemical device. In this specification, "main surface" means the surface of a plate-like member such as the catalyst layer 100 that has the largest area. The direction from the first main surface 101 to the second main surface 102 is defined as the thickness direction T100 of the catalyst layer 100. Figure 1 is a cross-sectional view of the catalyst layer 100 parallel to the thickness direction T100.

[0021] The catalyst layer 100 includes a conductive material 11, catalyst particles 12 supported on the conductive material 11, a first ionomer 31, and a second ionomer 32. The first ionomer 31 has a cyclic structure in its main chain. Because the first ionomer 31 has a cyclic structure in its main chain, it is permeable to gases such as oxygen, thus improving gas diffusion to the catalyst particles 12 supported on the conductive material 11. The second ionomer 32 has a different molecular structure from the first ionomer. The gas permeability of the second ionomer 32 is lower than that of the first ionomer 31. An example of the second ionomer 32 is an ionomer that does not have a cyclic structure in its main chain.

[0022] As shown in Figure 1, in the catalyst layer 100, the portion including the first main surface 101 and located on the side of the first main surface 101 is defined as the first portion 101p. The portion including the second main surface 102 and located on the side of the second main surface 102 is defined as the second portion 102p. The mass of the first portion 101p and the mass of the second portion 102p may be the same. In this case, in the catalyst layer 100, the ratio C1 (wt%) of the mass of the first ionomer 31 contained in the first portion 101p to the total mass of the resin components contained in the first portion 101p is greater than the ratio C2 (wt%) of the mass of the second ionomer 32 contained in the first portion 101p to the total mass of the resin components contained in the first portion 101p. The ratio C4 (wt%) of the mass of the second ionomer 32 contained in the second portion 102p to the total mass of the resin components contained in the second portion 102p is greater than the ratio C3 (wt%) of the mass of the first ionomer 31 contained in the second portion 102p to the total mass of the resin components contained in the second portion 102p. However, in this embodiment, "total mass of the resin components contained in the first portion 101p" means the sum of the mass of the first ionomer 31 and the mass of the second ionomer 32 contained in the first portion 101p. "Total mass of the resin components contained in the second portion 102p" means the sum of the mass of the first ionomer 31 and the mass of the second ionomer 32 contained in the second portion 102p.

[0023] Catalyst layers for electrochemical devices are manufactured, for example, by coating a catalyst ink containing catalyst particles, a conductive material, and an ionomer onto an electrolyte membrane and then drying it. The electrolyte membrane swells when the catalyst ink is applied, but shrinks as it dries, generating stress. In the manufacturing method described in Patent Document 1, the catalyst layer is manufactured by placing a second ionomer layer containing a second ionomer with higher oxygen permeability than the first ionomer on the electrolyte membrane side. As mentioned above, the second ionomer with high oxygen permeability tends to have low adsorption capacity to catalyst particles. Therefore, cracks may occur in the second ionomer layer made using the second ionomer due to stress generated by the shrinkage of the electrolyte membrane due to drying. Furthermore, when the electrochemical device is operated, the electrolyte membrane swells due to the inclusion of water generated during power generation. When the operation is stopped, the electrolyte membrane shrinks as the water is discharged, generating stress. In this case as well, cracks may occur in the second ionomer layer due to stress generated by the shrinkage of the electrolyte membrane. According to the manufacturing method described in Patent Document 2, a solution of ionomer adheres to the surface of the catalyst particles, and a highly oxygen-permeable gel-like ionomer adheres on top of that. As a result, the oxygen resistance at the interface between the solution of ionomer and the catalyst particles increases, which suppresses the improvement of power generation efficiency.

[0024] On the other hand, in the catalyst layer 100 of this embodiment, the occurrence of cracks in the catalyst layer 100 due to the stress generated by the shrinkage of the electrolyte membrane during the manufacturing of the catalyst layer 100 is suppressed. Specifically, the second portion 102p, which includes the second main surface 102 located on the electrolyte membrane side, contains more of the second ionomer 32, which has a higher adsorption capacity to the catalyst particles 12 than the first ionomer 31, so that the stress on the first portion 101p due to the shrinkage of the electrolyte membrane is relieved. In other words, the effect of the stress generated due to the shrinkage of the electrolyte membrane on the catalyst layer 100 is mitigated. As a result, the occurrence of cracks in the catalyst layer 100 is suppressed. As a result, a catalyst layer 100 with excellent durability and high power generation efficiency with an increased basis weight of catalyst particles 12 can be realized. Furthermore, according to the catalyst layer 100 of this embodiment, the occurrence of cracks in the catalyst layer 100 due to the shrinkage of the electrolyte membrane when the operation of the electrochemical device is stopped can also be suppressed.

[0025] In addition, in the catalyst layer 100, the first portion 101p, which includes the first main surface 101 located on the gas diffusion layer side, contains a larger amount of the first ionomer 31. Therefore, an interface is less likely to form between the second ionomer 32, which has lower gas permeability than the first ionomer 31, and the catalyst particles 12. As a result, the increase in oxygen resistance is suppressed in the first portion 101p. Consequently, the gas diffusivity in the first portion 101p is improved.

[0026] The mass ratio C1 (wt%) of the first ionomer 31 and the mass ratio C2 (wt%) of the second ionomer 32 contained in the first portion 101p are determined, for example, by fluorine-19 nuclear magnetic resonance (FNC) using a nuclear magnetic resonance spectrometer. 19 This can be determined by 1F-NMR measurement. As shown in the example in Figure 1, the first portion 101p (e.g., 50 mg) is scraped off from the catalyst layer 100 (e.g., 100 mg), and the resulting sample is dissolved in a non-deuterated solvent (NPA, 1-propanol) and water (H2O). 19The 1F-NMR measurement is performed under conditions of a resonance frequency of 375 MHz and a measurement temperature of 23°C. From the obtained NMR spectrum, the integral values ​​of the peaks originating from the first ionomer 31 and the integral values ​​of the peaks originating from the second ionomer 32 are identified. Using the identified integral values, the mass percentage C1 (wt%) of the first ionomer 31 and the mass percentage C2 (wt%) of the second ionomer 32 contained in the first portion 101p can be determined. The mass percentage C4 (wt%) of the second ionomer 32 and the mass percentage C3 (wt%) of the first ionomer 31 contained in the second portion 102p can be determined in the same manner. The masses of the first portion 101p and the second portion 102p may be the same. In addition, whether or not the ionomer has a cyclic structure in the main chain can be determined by using infrared absorption spectroscopy (IR) in combination.

[0027] The ratio of C2 to C1 (C2 / C1) may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, and even 0.5 or less. The lower limit of the ratio of C2 to C1 may be 0 (zero) or 0.05 or greater.

[0028] The ratio of C3 to C4 (C3 / C4) may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, and even 0.5 or less. The lower limit of the ratio of C3 to C4 may be 0 (zero) or 0.05 or greater.

[0029] In this embodiment, the catalyst layer 100 comprises a first layer 100a including a first portion 101p and a second layer 100b including a second portion 102p. The catalyst layer 100 having such a configuration is highly durable and suitable for improving power generation efficiency.

[0030] In the catalyst layer 100, the first layer 100a and the second layer 100b are in electrical contact. A catalyst layer 100 having such a configuration is suitable because it has excellent durability and improves power generation efficiency.

[0031] In the example shown in Figure 1, the first layer 100a and the second layer 100b are continuous in the thickness direction T100. Thus, the first layer 100a and the second layer 100b may be continuous. In other words, there does not need to be any other layer between the first layer 100a and the second layer 100b.

[0032] The second layer 100b may have a smaller thickness than the first layer 100a. With such a configuration, the content of the first ionomer 31 in the entire catalyst layer 100 can be increased, making it easier to improve the power generation efficiency of the catalyst layer 100.

[0033] The ratio R of the thickness of the second layer 100b to the thickness of the first layer 100a is, for example, in the range of 0.09 or more and 2.0 or less. The upper limit of the ratio R may be 1.8, 1.6, 1.4, 1.2, or even 1.0. The upper limit of the ratio R may be 0.9, 0.8, 0.7, 0.6, or even 0.5.

[0034] The thickness of the first layer 100a may be in the range of 5 μm to 21 μm. With such a configuration, it is easier to improve the power generation efficiency of the catalyst layer 100. The lower limit of the thickness of the first layer 100a may be 6 μm, 7 μm, 8 μm, 9 μm, or even 10 μm.

[0035] The thickness of the second layer 100b may be in the range of 2 μm to 9 μm. With this configuration, it is easier to improve the power generation efficiency of the catalyst layer 100.

[0036] The thickness of the catalyst layer 100 may be in the range of 12 μm to 30 μm. The upper limit of the thickness of the catalyst layer 100 may be 28 μm or 25 μm.

[0037] The thickness of the first layer 100a can be determined, for example, by the following method. First, a sample is prepared in which the cross-section of the catalyst layer 100 parallel to the thickness direction T100 is exposed. Multiple (e.g., 10) cross-sectional SEM images of the sample are obtained using a scanning electron microscope (SEM). The thickness of the first layer 100a is measured for each of the obtained SEM images. The boundary between the first layer 100a and the second layer 100b is, 19 Recognition can be achieved by combining this with F-NMR. The average of the measured values ​​is considered to be the thickness of the first layer 100a. The thickness of the second layer 100b can be determined in the same way. The thickness of the catalyst layer 100 can be determined as the average of the values ​​measured for multiple cross-sectional SEM images obtained.

[0038] In the catalyst layer 100, the ratio C5 (wt%) of the mass of the first ionomer 31 contained in the first layer 100a to the total mass of the resin components contained in the first layer 100a may be greater than the ratio C6 (wt%) of the mass of the second ionomer 32 contained in the first layer 100a to the total mass of the resin components contained in the first layer 100a, and the ratio C8 (wt%) of the mass of the second ionomer 32 contained in the second layer 100b to the total mass of the resin components contained in the second layer 100b may be greater than the ratio C7 (wt%) of the mass of the first ionomer 31 contained in the second layer 100b to the total mass of the resin components contained in the second layer 100b. However, in this embodiment, "total mass of the resin components contained in the first layer 100a" means the sum of the mass of the first ionomer 31 and the mass of the second ionomer 32 contained in the first layer 100a. "Total mass of resin components contained in the second layer 100b" means the sum of the mass of the first ionomer 31 and the mass of the second ionomer 32 contained in the second layer 100b.

[0039] The mass ratios C5 (wt%) of the first ionomer 31 and C6 (wt%) of the second ionomer 32 contained in the first layer 100a, and the mass ratios C8 (wt%) of the second ionomer 32 and C7 (wt%) of the first ionomer 31 contained in the second layer 100b can be determined by the same method as described above for the mass ratios C1 (wt%) of the first ionomer 31 and C2 (wt%) of the second ionomer 32 contained in the first portion 101p.

[0040] The ratio of C6 to C5 (C6 / C5) may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, and even 0.5 or less. The lower limit of the ratio of C6 to C5 may be 0 (zero) or 0.05 or greater.

[0041] The ratio of C7 to C8 (C7 / C8) may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, and even 0.5 or less. The lower limit of the ratio of C7 to C8 may be 0 (zero) or 0.05 or greater.

[0042] Figure 2A is a schematic cross-sectional view showing an example of a conductive material 11 supporting catalyst particles 12 and a first ionomer 31 that may be included in the first portion 101p of the catalyst layer 100. Figure 2B is a schematic cross-sectional view showing an example of a conductive material 11 supporting catalyst particles 12 and a second ionomer 32 that may be included in the second portion 102p of the catalyst layer 100. An electrochemical reaction is promoted on the surface of the catalyst particles 12.

[0043] As shown in Figures 2A and 2B, the conductive material 11 may be a conductive porous material having pores 11p. In this case, the pores 11p open to the surface of the conductive material 11. In other words, the surface of the conductive material 11 has irregularities. The pores 11p may be interconnected or independent.

[0044] As shown in FIGS. 2A and 2B, when the conductive material 11 is a conductive porous material having pores 11p, the catalyst particles 12 may be disposed inside the pores 11p of the conductive material 11. In this case, protons (H + ) can reach the catalyst particles 12 disposed inside the pores 11p through the first ionomer 31 or the second ionomer 32 attached to the surface of the conductive material 11. The first ionomer 31 has higher gas permeability than the second ionomer 32. Therefore, even if the first ionomer 31 located so as to cover the pores 11p of the conductive material 11 is present in the first portion 101p including the first main surface 101, oxygen (O2) can diffuse to the catalyst particles 12 disposed inside the pores 11p. As a result, the proton conductivity and the gas diffusibility such as oxygen to the catalyst particles 12 disposed inside the pores 11p can be increased, and the ratio of the catalyst particles 12 with sufficient supply of gas, protons, and electrons (e - ) can be increased. As a result, the utilization rate of the catalyst particles 12 supported on the conductive material 11 can be improved.

[0045] When the conductive material 11 is a conductive porous material having pores 11p, in the catalyst layer 100, the pore diameter in the first layer 100a may be larger than the pore diameter in the second layer 100b. When the catalyst layer 100 is used as the cathode catalyst layer of an electrochemical device, the oxygen-containing gas (O2) supplied from the cathode gas diffusion layer side (the first main surface 101 side) can move in the catalyst layer 100, for example, along the pores 11p of the conductive material 11. Protons (H + ) that have moved from the electrolyte membrane side (the second main surface 102 side) can move in the catalyst layer 100 along the liquid water. In the catalyst layer 100, the oxygen-containing gas is electrons (e -) reacts with protons, and as a result, water is produced. At this time, in the catalyst layer 100 where the pore diameter in the first layer 100a is larger than the pore diameter in the second layer 100b, capillary pressure can act to raise the liquid level in the direction from the second main surface 102 toward the first main surface 101. Due to this capillary pressure, the water produced in the pores 11p is pushed upward in the direction from the second main surface 102 toward the first main surface 101. This promotes the discharge of the produced water from the catalyst layer 100, and thus suppresses the blockage of the pores 11p of the conductive material 11 by water. As a result, the increase in the diffusion resistance of reactants, especially oxygen, in the catalyst layer 100 is suppressed, and the output of the electrochemical device can be improved.

[0046] The pore diameter in the first layer 100a can be determined, for example, by the following method. First, a sample is prepared in which the cross-section of the first layer 100a of the catalyst layer 100, which is parallel to the thickness direction T100, is exposed. An SEM is used to obtain a cross-sectional SEM image of the sample. The SEM image (or a part thereof) is binarized. Pores are identified from the obtained binarized image, and the area of ​​each pore included in the image is calculated. For each pore, the equivalent circle diameter is calculated from the calculated area. The equivalent circle diameter is the diameter of a true circle having the same area as the pore being measured. The average of the calculated equivalent circle diameters can be considered as the pore diameter in the first layer 100a. The pore diameter is determined from the areas of 30 or more pores, for example, 50 to 100 pores. When identifying pores, pores that fall at the edges of the image are excluded. The pore diameter in the second layer 100b can be determined by the same method.

[0047] The conductive material 11 may be porous conductive particles such as carbon particles. Typically, the conductive material 11 is mesoporous carbon particles. When the conductive material 11 is mesoporous carbon particles, its average particle size is, for example, 0.6 μm to 2.0 μm.

[0048] Examples of carbon particles include furnace black and acetylene black particles. The conductive material 11 may contain at least one selected from the group consisting of furnace black, acetylene black, and thermal black. Furnace black includes those using petroleum-based hydrocarbons or coal-based hydrocarbons as raw materials, and gas furnace black using natural gas as a raw material.

[0049] The catalyst particles 12 are not particularly limited as long as they are metal particles that have a reducing effect on oxygen-containing gases. From the viewpoint of improving the catalytic activity and heat resistance of the catalyst layer 100, the material of the catalyst particles 12 may be particles containing noble metals such as platinum and platinum alloys. Examples of platinum alloys include alloys of platinum and at least one selected from the group consisting of cobalt, nickel, ruthenium, and palladium. The catalyst particles 12 may also contain at least one selected from the group consisting of platinum, palladium, iridium, ruthenium, and rhodium.

[0050] The platinum content in the catalyst particles 12 may be 30 atomic% or more and 90 atomic% or less, and the content of other metals (e.g., cobalt) may be 10 atomic% or more and 70 atomic% or less.

[0051] The average particle diameter of the catalyst particles 12 is not particularly limited. From the viewpoint of catalyst utilization rate and durability, it is desirable that the average particle diameter of the catalyst particles 12 be between 1 nm and 30 nm. The average particle diameter can be calculated, for example, from a cross-sectional image of the catalyst layer 100 obtained using TEM or SEM. In the cross-sectional image, the equivalent diameter of any number (e.g., 10) of catalyst particles 12 is measured. The average of the equivalent diameters can be considered as the average particle diameter.

[0052] As shown in Figure 2A, the first ionomer 31 may be attached to the surface of the conductive material 11. As shown in Figure 2B, the second ionomer 32 may be attached to the surface of the conductive material 11. If the conductive material 11 is a conductive porous material having pores 11p, the first ionomer 31 may be present so as to cover the pores 11p of the conductive material 11. The second ionomer 32 may be present so as to cover the pores 11p of the conductive material 11.

[0053] As the first ionomer 31 and the second ionomer 32, polymer electrolytes having ionic conductivity such as protons can be used. The first ionomer 31 and the second ionomer 32 link the catalyst particles 12 and the conductive material 11 in a state that allows for ionic conduction. As the first ionomer 31 and the second ionomer 32, for example, perfluorocarbon sulfonic acid-based polymer materials having sulfonic acid groups, hydrocarbon-based polymer materials, etc., can be used. Perfluorosulfonic acid resins may also be used as the first ionomer 31 and the second ionomer 32. Perfluorosulfonic acid resins exhibit excellent proton conductivity and remain stable even under the power generation environment of electrochemical devices. The first ionomer 31 and the second ionomer 32 typically contain perfluorocarbon sulfonic acid-based polymer electrolytes having sulfonic acid groups.

[0054] As described above, the first ionomer 31 has a cyclic structure in its main chain. Having a cyclic structure in its main chain can increase the volume and decrease the density of the ionomer. Therefore, such a first ionomer 31 is permeable to gases such as oxygen. The cyclic structure may be a five-membered ring structure or a six-membered ring structure.

[0055] The first ionomer 31 may be a high oxygen permeability ionomer (HOPI). In this specification, a high oxygen permeability ionomer is an ionomer whose oxygen permeability is improved by having a sterically hindrance cyclic structure in the main chain. High oxygen permeability ionomers can exhibit excellent oxygen permeability.

[0056] The first ionomer 31 may have a cyclic structure in both the main chain and the side chains. The first ionomer 31 having a cyclic structure in both the main chain and the side chains is more permeable to gases such as oxygen. As a result, for example, the diffusibility of gases such as oxygen to catalyst particles 12 placed inside the pores 11p can be further improved.

[0057] The first ionomer 31 may also be represented by the following formula (1), which includes multiple types of repeating units.

[0058] [ka]

[0059] In equation (1) above, m and n represent numbers greater than 0, independently of each other.

[0060] As described above, the gas permeability of the second ionomer 32 is lower than that of the first ionomer 31. The second ionomer 32 does not need to have a cyclic structure in its main chain. The second ionomer 32 does not need to have a cyclic structure in both its main chain and side chains. Such an ionomer can reduce the volume of the ionomer and increase its density. Therefore, the second ionomer 32 without a cyclic structure can easily penetrate, for example, the pores 11p of the conductive material 11. As a result, the proton conductivity to the catalyst particles 12 placed inside the pores 11p can be improved.

[0061] The second ionomer 32 may have linear structures in its main chain and side chains. The second ionomer 32 having linear structures in its main chain and side chains can reduce the volume of the ionomer and increase its density. Therefore, the second ionomer 32 having linear structures in its main chain and side chains can easily penetrate, for example, the pores 11p of the conductive material 11. As a result, the proton conductivity to the catalyst particles 12 placed inside the pores 11p can be improved.

[0062] The second ionomer 32 may also be represented by the following formula (2), which includes multiple types of repeating units.

[0063] [ka]

[0064] In equation (2) above, x and y represent numbers greater than 0, independently of each other.

[0065] Formula (2) above may also be a random copolymer.

[0066] The second ionomer 32 may have a molecular structure in which 2 to 20 hydrophobic parts and 2 to 10 hydrophilic parts are randomly bonded together.

[0067] From another perspective, the first ionomer 31 may have a lower density than the second ionomer 32.

[0068] The densities of the first ionomer 31 and the second ionomer 32 can be determined, for example, by the following method using a catalyst layer formation process simulator based on molecular dynamics coarse-graining. First, the ionomers are placed on the surface of Pt nanoparticles, and simulation results are obtained showing the density of the ionomer near the interface between the Pt nanoparticles and the ionomers. The simulation results show the relationship between the distance from the surface of the Pt nanoparticles and the density of the ionomers. Density of the ionomer (g / cm³) in the range where the distance from the surface of the Pt nanoparticles is 7 Å or less. 3The average value of ) can be considered as the density of the ionomer.

[0069] The densities of the first ionomer 31 and the second ionomer 32 can also be determined, for example, by the pycnometer method. Specifically, the volume of the ionomer sample is determined using, for example, a He gas-substituted pycnometer. From the determined volume and the mass of the ionomer sample measured separately, the density of the ionomer can be calculated.

[0070] The density of the first ionomer 31 is, for example, 1.3 g / cm³. 3 More than 2.0g / cm 3 The following ranges may also apply: The density of the second ionomer 32 is, for example, 2.0 g / cm³. 3 Super 3.3g / cm 3 It may also be within the following range.

[0071] Although not shown in the diagram, the catalyst layer 100 may further comprise a fibrous conductive material. A first ionomer 31 or a second ionomer 32 may be attached to the surface of the fibrous conductive material. With such a configuration, for example, in the first layer 100a, the first ionomer 31 attached to the surface of the conductive material 11 and the first ionomer 31 attached to the surface of the fibrous conductive material are more likely to bond. For example, in the second layer 100b, the second ionomer 32 attached to the surface of the conductive material 11 and the second ionomer 32 attached to the surface of the fibrous conductive material are more likely to bond. Therefore, the proton conductivity in the catalyst layer 100 can be further improved.

[0072] Next, the manufacturing method for the catalyst layer 100 described above will be explained.

[0073] Figure 3 is a flowchart showing an example of a method for manufacturing the catalyst layer 100. The method for manufacturing the catalyst layer 100 includes, for example, dispersing a conductive material 11 on which catalyst particles 12 are supported and a first ionomer 31 having a cyclic structure in its main chain in a first solvent to prepare a first solution (step S1); dispersing the conductive material 11 on which catalyst particles 12 are supported and a second ionomer 32 having a different molecular structure from the first ionomer 31 in a second solvent to prepare a second solution (step S2); coating the second solution onto an electrolyte membrane to form a second coating film (step S3); removing the second solvent from the second coating film to produce a second layer 100b (step S4); coating the first solution onto the second layer 100b to form a first coating film (step S5); and removing the first solvent from the first coating film to produce a first layer 100a (step S6). According to this manufacturing method, the first layer 100a can be formed on the second layer 100b formed on the electrolyte membrane, so that cracks are less likely to occur in the catalyst layer 100 due to the stress generated by the shrinkage of the electrolyte membrane during manufacturing. Therefore, it is possible to manufacture a catalyst layer 100 that is highly durable and suitable for improving power generation efficiency by increasing the basis weight of the catalyst particles 12. Furthermore, in the catalyst layer 100 manufactured by this manufacturing method, the occurrence of cracks in the catalyst layer 100 due to the shrinkage of the electrolyte membrane when the operation of the electrochemical device is stopped can also be suppressed.

[0074] The manufacturing method may include supporting catalyst particles 12 on a conductive material 11 (step S0) before step S1.

[0075] In step S0, the method for supporting the catalyst particles 12 on the conductive material 11 is not particularly limited. For example, if the conductive material 11 is a conductive porous material having pores 11p, and the catalyst particles 12 are to be placed inside the pores 11p, the conductive material 11 is dispersed in a solvent, a metal precursor solution such as a platinum precursor is added, the mixture is stirred to prepare a mixed solution, and the resulting mixed solution is filtered and dried. This allows the catalyst particles 12 to be placed inside the pores 11p of the conductive material 11.

[0076] Step S0 may include producing a conductive material 11 having pores 11p. For example, a porous conductive material 11 can be produced by heat-treating the raw material composite, then washing it with dilute sulfuric acid and drying it.

[0077] In step S1, the conductive material 11 on which the catalyst particles 12 are supported and the first ionomer 31 are dispersed in a first solvent to prepare the first solution. For example, an aqueous ethanol solution can be used as the first solvent.

[0078] For example, a first catalyst solution can be obtained by adding a conductive material 11 on which catalyst particles 12 are supported to a first solvent, and then adding a first ionomer 31 to the first catalyst solution and stirring to obtain the first solution.

[0079] In step S2, the conductive material 11 on which the catalyst particles 12 are supported and the second ionomer 32 are dispersed in a second solvent to prepare a second solution. For example, an aqueous ethanol solution can be used as the second solvent.

[0080] For example, a second catalyst solution can be obtained by adding a conductive material 11 on which catalyst particles 12 are supported to a second solvent, and then adding a second ionomer 32 to the second catalyst solution and stirring to obtain a second solution.

[0081] In step S3, the second solution is applied to the electrolyte membrane to form a second coating film. This allows for the easy formation of a second layer 100b on the electrolyte membrane.

[0082] In step S4, the second solvent is removed from the second coating film to produce the second layer 100b. The method for removing the solvent from the coating film is not particularly limited. For example, the solvent may be removed from the coating film by air drying or by heating. After step S4, the second layer 100b is formed on the electrolyte film.

[0083] In step S5, the first solution is applied to the second layer 100b to form the first coating film. The thickness of the first coating film may be greater than the thickness of the second coating film.

[0084] In step S5, a portion of the first solution penetrates into the second layer 100b, potentially filling some of the pores in the second layer 100b. As a result, in the final catalyst layer 100, the pore diameter in the first layer 100a may be larger than the pore diameter in the second layer 100b. Therefore, when the catalyst layer 100 is used as the cathode catalyst layer of a fuel cell, as described above, the discharge of generated water from the catalyst layer 100 is promoted, thereby suppressing the blockage of the pores 11p of the conductive material 11 by water. Consequently, the increase in the diffusion resistance of reactants, particularly oxygen, in the catalyst layer 100 is suppressed, thereby improving the output of the electrochemical device.

[0085] In step S6, the first solvent is removed from the first coated film to prepare the first layer 100a. After step S6, the catalyst layer 100 is formed on the electrolyte film.

[0086] [1-2. Operation] The operation and function of the catalyst layer 100 configured as described above will be explained in the electrochemical device 300 of Embodiment 2, which will be described later.

[0087] (Embodiment 2) Embodiment 2 will be described below with reference to Figures 4A to 5.

[0088] [2-1. Structure] Figure 4A is a schematic cross-sectional view of the membrane electrode assembly 200 in Embodiment 2. Figure 4B is a partially enlarged view of part IVB in Figure 4A. Figure 5 is a schematic cross-sectional view of the electrochemical device 300 in Embodiment 2. The electrochemical device 300 comprises the membrane electrode assembly 200, an anode separator 301, and a cathode separator 302. The membrane electrode assembly 200 is positioned between the anode separator 301 and the cathode separator 302.

[0089] In this embodiment, the electrochemical device 300 may be used in a fuel cell. In this way, a fuel cell with high power generation performance and high efficiency can be obtained.

[0090] In the example shown in Figure 5, the electrochemical device 300 is a polymer electrolyte fuel cell (PEFC) that generates electricity by receiving hydrogen-containing gas G1 as the anode gas and oxygen-containing gas G3 as the cathode gas. In addition to being a fuel cell, the electrochemical device 300 may also be used as other electrochemical devices such as a hydrogen purification device for purifying hydrogen or a water electrolysis device for electrolyzing water.

[0091] As shown in Figure 4A, the membrane electrode assembly 200 has an anode 202, an electrolyte membrane 201, and a cathode 203. The electrolyte membrane 201 is positioned between the anode 202 and the cathode 203. The anode 202 is bonded to one side of the electrolyte membrane 201. The cathode 203 is bonded to the other side of the electrolyte membrane 201.

[0092] Anode 202 has an anode catalyst layer 204 and an anode gas diffusion layer 205. The anode catalyst layer 204 is positioned between the electrolyte membrane 201 and the anode gas diffusion layer 205. Cathode 203 has a cathode catalyst layer 206 and a cathode gas diffusion layer 207. The cathode catalyst layer 206 is positioned between the electrolyte membrane 201 and the cathode gas diffusion layer 207.

[0093] The electrolyte membrane 201 facilitates proton conduction between the anode catalyst layer 204 and the cathode catalyst layer 206. The electrolyte membrane 201 is made of a polymer material having proton conductivity and gas barrier properties. Typically, the electrolyte membrane 201 is a perfluorocarbon sulfonic acid-based or hydrocarbon-based polymer electrolyte membrane having sulfonic acid groups. The electrolyte membrane 201 may also be a perfluorosulfonic acid-based polymer electrolyte membrane. Perfluorosulfonic acid-based polymer electrolyte membranes exhibit excellent proton conductivity and remain stable even under the power generation environment of the electrochemical device 300.

[0094] The electrolyte membrane 201 has a surface in contact with the anode catalyst layer 204 and a surface in contact with the cathode catalyst layer 206. These surfaces are flat. When the surface of the electrolyte membrane 201 is flat, drainage on the surface of the electrolyte membrane 201 is good. "Flat surface" means a surface that has not been processed to create irregularities.

[0095] The anode catalyst layer 204 has the function of promoting an electrochemical reaction that dissociates hydrogen into protons. The anode catalyst layer 204 includes a conductive material and catalyst particles supported on the conductive material. The anode catalyst layer 204 may further include an ionomer.

[0096] The membrane electrode assembly 200 may include the catalyst layer 100 described in Embodiment 1 as the anode catalyst layer 204.

[0097] The anode gas diffusion layer 205 has the function of supplying hydrogen-containing gas G1 to the anode catalyst layer 204 and receiving electrons from the anode catalyst layer 204. The anode gas diffusion layer 205 is composed of a material that is gas permeable, water-repellent, and conductive. The anode gas diffusion layer 205 has, for example, a conductive porous material as its main material. Examples of porous materials include carbon fiber aggregates such as carbon paper.

[0098] The cathode catalyst layer 206 has the function of promoting an electrochemical reaction that produces water from protons and oxygen. The cathode catalyst layer 206 includes a conductive material and catalyst particles supported on the conductive material. The cathode catalyst layer 206 further includes an ionomer.

[0099] In this embodiment, the cathode 203 includes the catalyst layer 100 described in Embodiment 1. That is, the membrane electrode assembly 200 includes the catalyst layer 100 described in Embodiment 1 as the cathode catalyst layer 206. Therefore, the cathode catalyst layer 206 includes a first ionomer 31 having a cyclic structure and a second ionomer 32 having a different molecular structure from the first ionomer 31 as ions. Figure 4B shows an example where the membrane electrode assembly 200 includes the catalyst layer 100 as the cathode catalyst layer 206. As shown in Figure 4B, the first main surface 101 of the cathode catalyst layer 206 is in contact with the cathode gas diffusion layer 207. The second main surface 102 of the cathode catalyst layer 206 is in contact with the electrolyte membrane 201. With this configuration, oxygen and protons necessary for the power generation reaction can be smoothly moved in the cathode catalyst layer 206. As a result, the electrochemical reaction of the cathode catalyst layer 206 can be promoted. This makes it possible to improve the power generation performance of the electrochemical device 300 using the membrane electrode assembly 200.

[0100] The cathode gas diffusion layer 207 has the function of supplying oxygen-containing gas to the cathode catalyst layer 206 and transferring electrons to the cathode catalyst layer 206. The cathode gas diffusion layer 207 is composed of a material that is gas permeable, water-repellent, and conductive. The cathode gas diffusion layer 207 mainly consists of a conductive porous material, for example. Examples of porous materials include carbon fiber aggregates such as carbon paper.

[0101] The anode catalyst layer 204 may have the same structure as the cathode catalyst layer 206, or it may have a different structure.

[0102] As shown in Figure 5, the anode separator 301 has an anode gas inlet 303, an anode gas outlet 304, and an anode gas channel 301g. The anode gas channel 301g is a groove-shaped gas channel that guides hydrogen-containing gas G1 to the anode 202. The anode gas inlet 303 is provided at the upstream end of the anode gas channel 301g. The anode gas outlet 304 is provided at the downstream end of the anode gas channel 301g. Hydrogen-containing gas G1 is introduced into the anode gas channel 301g from the outside through the anode gas inlet 303. Unreacted hydrogen-containing gas G2 is discharged to the outside from the anode gas channel 301g through the anode gas outlet 304. The direction of anode gas flow in the anode separator 301 is parallel to the main surface of the anode separator 301.

[0103] The cathode separator 302 has a cathode gas inlet 305, a cathode gas outlet 306, and a cathode gas flow path 302g. The cathode gas flow path 302g is a groove-shaped gas flow path that guides oxygen-containing gas G3 to the cathode 203. The cathode gas inlet 305 is provided at the upstream end of the cathode gas flow path 302g. The cathode gas outlet 306 is provided at the downstream end of the cathode gas flow path 302g. Oxygen-containing gas G3 is introduced into the cathode gas flow path 302g from the outside through the cathode gas inlet 305. Unreacted oxygen-containing gas G4 is discharged from the cathode gas flow path 302g to the outside through the cathode gas outlet 306. The direction of cathode gas flow in the cathode separator 302 is parallel to the main surface of the cathode separator 302.

[0104] The shapes of the anode gas channel 301g and the cathode gas channel 302g are not particularly limited. The anode gas channel 301g and the cathode gas channel 302g may each have a serpentine shape. A serpentine shape is the shape of a channel in which one or more channels meander within a plane. If the anode gas channel 301g and the cathode gas channel 302g have the above shapes, gas can be supplied to the entire catalyst layers 204 and 206 at a constant flow rate. This makes it easier for the gas to reach all of the catalyst particles.

[0105] The anode separator 301 and cathode separator 302 are made of conductive material. The anode separator 301 and cathode separator 302 may each be made of a conductive material such as carbon or metal. To prevent corrosion, the anode separator 301 and cathode separator 302 may be provided with a corrosion-resistant coating such as resin or plating.

[0106] [2-2. Operation] The operation and function of the electrochemical device 300, configured as described above, will be explained below with reference to Figure 5.

[0107] Hydrogen-containing gas G1 is supplied to the anode gas channel 301g of the anode separator 301 from the anode gas inlet 303. Hydrogen-containing gas G1 is a humidified gas containing hydrogen. The humidified gas containing hydrogen may be, for example, humidified hydrogen gas. This supplies hydrogen-containing gas G1 to the anode catalyst layer 204 via the anode gas diffusion layer 205. Oxygen-containing gas G3 is supplied to the cathode gas channel 302g of the cathode separator 302 from the cathode gas inlet 305. Oxygen-containing gas G3 is a humidified gas containing oxygen. The humidified gas containing oxygen may be, for example, humidified air. This supplies oxygen-containing gas G3 to the cathode catalyst layer 206 via the cathode gas diffusion layer 207. This makes it possible to draw current from between the anode catalyst layer 204, which is supplied with hydrogen-containing gas G1, and the cathode catalyst layer 206, which is supplied with oxygen-containing gas G3.

[0108] In the anode catalyst layer 204 supplied with hydrogen-containing gas G1, hydrogen (H2) is converted into protons (H2) in an electrochemical reaction represented by the following equation (I). + ) and electrons (e -An oxidation reaction occurs in which the protons dissociate into protons and electrons. The protons move through the electrolyte membrane 201 to the cathode catalyst layer 206. The electrons dissociated in the anode catalyst layer 204 move from the anode 202 to the cathode 203 through the external circuit 401 equipped with a load 402, and reach the cathode catalyst layer 206. In the cathode catalyst layer 206, a reduction reaction occurs in which water (H2O) is produced by an electrochemical reaction of protons, oxygen (O2), and electrons, as shown in the following equation (II). The protons used in this reduction reaction are those that dissociated in the oxidation reaction in the anode catalyst layer 204 shown in the following equation (I), and moved through the electrolyte membrane 201 to the cathode catalyst layer 206.

[0109] H2→2H + +2e - (I) 4H + +O2+4e - →2H2O (II)

[0110] In the electrochemical device 300, oxygen and protons necessary for the power generation reaction can be smoothly transferred in the cathode catalyst layer 206. As a result, the electrochemical reaction in the cathode catalyst layer 206 can be accelerated.

[0111] (Other embodiments) As described above, Embodiments 1 and 2 have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, added to, or omitted. Furthermore, it is possible to create new embodiments by combining the components described in the above embodiments and modifications.

[0112] The embodiments described above are for illustrative purposes only and may be modified, replaced, added, or omitted within the scope of the claims or equivalents.

[0113] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0114] (Technology 1) A catalyst layer having a first main surface to be positioned on the gas diffusion layer side and a second main surface to be positioned on the electrolyte membrane side in an electrochemical device, The material comprises a conductive material, catalyst particles supported on the conductive material, a first ionomer having a cyclic structure in its main chain, and a second ionomer having a molecular structure different from that of the first ionomer. When the portion including the first main surface and located on the side of the first main surface is defined as the first portion, and the portion including the second main surface and located on the side of the second main surface is defined as the second portion, The ratio of the mass of the first ionomer contained in the first portion to the total mass of the resin components contained in the first portion is greater than the ratio of the mass of the second ionomer contained in the first portion to the total mass of the resin components contained in the first portion. The ratio of the mass of the second ionomer contained in the second portion to the total mass of the resin components contained in the second portion is greater than the ratio of the mass of the first ionomer contained in the second portion to the total mass of the resin components contained in the second portion. Catalyst layer for electrochemical devices.

[0115] According to the catalyst layer for electrochemical devices of Technology 1, it is possible to realize a catalyst layer with excellent durability and high power generation efficiency by increasing the basis weight of catalyst particles.

[0116] (Technology 2) A catalyst layer for an electrochemical device according to Art 1, comprising a first layer including the first portion and a second layer including the second portion, wherein the second layer has a smaller thickness than the first layer. A catalyst layer having such a configuration is highly durable and suitable for improving power generation efficiency.

[0117] (Technology 3) A catalyst layer for an electrochemical device according to Technology 2, wherein the first layer and the second layer are in electrical contact. A catalyst layer having such a configuration is suitable because it is highly durable and improves power generation efficiency.

[0118] (Technology 4) The catalyst layer for the electrochemical device according to Technology 2 or 3, wherein the thickness of the second layer is in the range of 2 μm to 9 μm. With such a configuration, it is easier to improve the power generation efficiency of the catalyst layer.

[0119] (Technology 5) The second ionomer is a catalyst layer for an electrochemical device according to any one of the art items 1 to 4, which does not have a cyclic structure. With such a configuration, it is easy to improve the power generation efficiency of the catalyst layer.

[0120] (Technology 6) The conductive material is a conductive porous material having pores, and the catalyst particles are arranged inside the pores of the conductive material, wherein this is a catalyst layer for an electrochemical device according to any one of the art 1 to 5. With this configuration, the utilization rate of the catalyst particles supported on the conductive material can be improved.

[0121] (Technology 7) A-scatter, Cathode and, An electrolyte membrane disposed between the anode and the cathode, Equipped with, The cathode includes a catalyst layer for an electrochemical device as described in any one of the Art 1 to 6. Membrane electrode assembly.

[0122] According to the membrane electrode assembly of Technology 7, the power generation performance of electrochemical devices using the membrane electrode assembly can be improved.

[0123] (Technology 8) A membrane electrode assembly as described in Technical 7, Electrochemical devices.

[0124] According to the electrochemical device of Technology 8, it is possible to realize an electrochemical device with excellent power generation performance and high efficiency.

[0125] (Technology 9) The first solution is prepared by dispersing a conductive material on which catalyst particles are supported and a first ionomer having a cyclic structure in its main chain in a first solvent, The second solution is prepared by dispersing the conductive material on which the catalyst particles are supported and a second ionomer having a different molecular structure from the first ionomer in a second solvent. The aforementioned second solution is applied to the electrolyte membrane to form a second coating film, The second solvent is removed from the second coating film to produce a second layer, The first solution is applied to the second layer to form a first coating film, The first solvent is removed from the first coating film to produce a first layer, including, A method for manufacturing a catalyst layer for electrochemical devices.

[0126] According to the method for manufacturing a catalyst layer for electrochemical devices of Technology 9, it is possible to manufacture a catalyst layer that is highly durable and suitable for improving power generation efficiency by increasing the basis weight of catalyst particles. [Industrial applicability]

[0127] This disclosure is useful for electrochemical devices such as fuel cells, hydrogen purification devices, and water electrolysis devices. [Explanation of Symbols]

[0128] 100 Catalyst layer for electrochemical devices 101 First main surface 102 Second main surface Page 101, Part 1 Page 102, Part 2 100a First layer 100b Second layer 11. Conductive materials 11p pores 12 catalyst particles 31. First Ionomer 32 Second Ionomer T100 Thickness direction 200 Membrane electrode assembly 201 Electrolyte membrane 202 Anodes 203 Cathode 204 Anode catalyst layer 205 Anode gas diffusion layer 206 Cathode catalyst layer 207 Cathode gas diffusion layer 300 Electrochemical Devices 301 Anode Separator 301g Anode gas flow path 302 Cathode Separator 302g Cathode gas flow path 303 Anode gas inlet 304 Anode Gas Outlet 305 Cathode Gas Inlet 306 Cathode Gas Outlet 401 External circuit 402 load

Claims

1. A catalyst layer having a first main surface to be positioned on the gas diffusion layer side and a second main surface to be positioned on the electrolyte membrane side in an electrochemical device, The material comprises a conductive material, catalyst particles supported on the conductive material, a first ionomer having a cyclic structure in its main chain, and a second ionomer having a molecular structure different from that of the first ionomer. When the portion including the first main surface and located on the side of the first main surface is defined as the first portion, and the portion including the second main surface and located on the side of the second main surface is defined as the second portion, The ratio of the mass of the first ionomer contained in the first portion to the total mass of the resin components contained in the first portion is greater than the ratio of the mass of the second ionomer contained in the first portion to the total mass of the resin components contained in the first portion. The ratio of the mass of the second ionomer contained in the second portion to the total mass of the resin components contained in the second portion is greater than the ratio of the mass of the first ionomer contained in the second portion to the total mass of the resin components contained in the second portion. Catalyst layer for electrochemical devices.

2. It comprises a first layer including the first portion and a second layer including the second portion, The second layer has a smaller thickness than the first layer. A catalyst layer for an electrochemical device according to claim 1.

3. The first layer and the second layer are in electrical contact. A catalyst layer for an electrochemical device according to claim 2.

4. The thickness of the second layer is in the range of 2 μm to 9 μm. A catalyst layer for an electrochemical device according to claim 2.

5. The second ionomer does not have a ring structure. A catalyst layer for an electrochemical device according to claim 1.

6. The conductive material is a conductive porous material having pores. The catalyst particles are arranged inside the pores of the conductive material. A catalyst layer for an electrochemical device according to claim 1.

7. A-scatter, Cathode and, An electrolyte membrane disposed between the anode and the cathode, Equipped with, The cathode includes a catalyst layer for an electrochemical device according to any one of claims 1 to 6. Membrane electrode assembly.

8. A membrane electrode assembly comprising the membrane electrode assembly described in claim 7, Electrochemical devices.

9. The first solution is prepared by dispersing a conductive material on which catalyst particles are supported and a first ionomer having a cyclic structure in its main chain in a first solvent, The second solution is prepared by dispersing the conductive material on which the catalyst particles are supported and the second ionomer having a different molecular structure from the first ionomer in a second solvent. The second solution is applied to the electrolyte membrane to form a second coating film, The second solvent is removed from the second coating film to produce a second layer, The first solution is applied to the second layer to form a first coating film, The first solvent is removed from the first coating film to produce a first layer, including, A method for manufacturing a catalyst layer for electrochemical devices.

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