Electrolyte membrane with catalyst layer, fuel cell, and water electrolysis hydrogen generator

Abstract

To provide an electrolyte membrane with a catalyst layer that can exhibit good power generation performance under high temperature and low humidity conditions. [Solution] A catalyst-coated electrolyte membrane comprising an anode catalyst layer, a cathode catalyst layer, and a solid polymer electrolyte membrane sandwiched between the anode catalyst layer and the cathode catalyst layer, wherein the cathode catalyst layer comprises a transition metal catalyst supported on conductive particles and a polymer electrolyte, and the BET specific surface area of ​​the cathode catalyst layer is 31 m². 2 A catalyst-coated electrolyte membrane with a concentration of 1 / g or more.

Description

[Technical Field]

[0001] The present invention relates to an electrolyte membrane with a catalyst layer, a fuel cell, and a water electrolysis type hydrogen generator. [Background technology]

[0002] Fuel cells are a type of power generation device that extracts electrical energy by electrochemically oxidizing fuels such as hydrogen and methanol, and are attracting attention as a clean energy source. Among them, polymer electrolyte fuel cells are expected to have a wide range of applications as power generation devices for mobile vehicles such as automobiles and ships, due to their relatively low operating temperature and high energy density.

[0003] A polymer electrolyte fuel cell (MSF) is composed of multiple cells in which an anode and a cathode are arranged opposite each other with a solid polymer electrolyte membrane in between. It generates electricity by supplying fuel (hydrogen or methanol) to the anode and an oxidizing gas (air or oxygen) to the cathode. In such a MSF, in order to promote the discharge of generated water and improve the power generation performance at high current densities, a method has been proposed in which silica particles are added to the catalyst layer to form a catalyst-coated electrolyte membrane (CCM) to which a solid polymer electrolyte membrane is bonded, and then the silica particles are removed to intentionally create pores in the catalyst layer (see, for example, Patent Document 1).

[0004] In addition, to improve fuel cell performance, various methods have been proposed, such as supporting catalyst particles on an ionomer used as a binder for catalyst particles to form a thin catalyst layer with a high specific surface area (see, for example, Patent Document 2), making the specific surface area of ​​the catalyst metal in the cathode larger than that of the anode (see, for example, Patent Document 3), and adding carbon particles without catalyst support to the anode catalyst layer to improve durability (see, for example, Patent Document 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-228261 [Patent Document 2 Japanese Patent Application Laid-Open No. 2006-19298 [Patent Document 3 Japanese Patent Application Laid-Open No. 2019-522323 [Patent Document 4 International Publication No. 2009 / 104373 [Summary of the Invention [Problems to be Solved by the Invention

[0006] In the field of fuel cells, it is required to have high power generation performance under high-temperature and low-humidity conditions. However, the technologies described in the above patent documents are still insufficient.

[0007] Therefore, an object of the present invention is to provide a catalyst-coated electrolyte membrane (Catalyst Coated Membrane, CCM) that can exhibit good power generation performance under high-temperature and low-humidity conditions in view of the above problems. [Means for Solving the Problems

[0008] The above object of the present invention is achieved by the following invention. That is, [1] A catalyst-coated electrolyte membrane including an anode catalyst layer, a cathode catalyst layer, and a solid polymer electrolyte membrane sandwiched between the anode catalyst layer and the cathode catalyst layer, wherein the cathode catalyst layer includes a transition metal catalyst supported on conductive particles and a polymer electrolyte, and the BET specific surface area of the cathode catalyst layer is 31 m 2 / g or more. Catalyst-coated electrolyte membrane. [2] The catalyst-coated electrolyte membrane according to [1], wherein the BET specific surface area of the cathode catalyst layer is 150 m 2 / g or less. [3] The catalyst-coated electrolyte membrane according to [1], wherein the BET specific surface area of the cathode catalyst layer is 50 m 2 / g or less. [4] The electrolyte membrane with a catalyst layer according to any one of [1] to [3], wherein the conductive particles contained in the cathode catalyst layer include at least one selected from the group consisting of metal particles, metal oxide particles, and carbon particles. [5] The electrolyte membrane with a catalyst layer according to any one of [1] to [4], wherein the conductive particles contained in the cathode catalyst layer are carbon particles. [6] The electrolyte membrane with a catalyst layer according to any one of [1] to [5], wherein the transition metal catalyst contained in the cathode catalyst layer comprises at least one selected from the group consisting of platinum, gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium, cobalt, manganese, nickel, and two or more alloys thereof. [7] The catalyst layer-equipped electrolyte membrane according to any one of [1] to [6], wherein the polymer electrolyte contained in the cathode catalyst layer is a fluorine-based polymer electrolyte. [8] The catalyst layer-equipped electrolyte membrane according to any one of [1] to [7], wherein the solid polymer electrolyte membrane comprises a hydrocarbon polymer electrolyte. [9] The catalyst layer-equipped electrolyte membrane according to any one of [1] to [8], wherein the solid polymer electrolyte membrane comprises an aromatic hydrocarbon polymer electrolyte. A fuel cell comprising an electrolyte membrane with a catalyst layer as described in any of

[10] [1] to [9]. A water electrolysis hydrogen generator comprising an electrolyte membrane with a catalyst layer as described in any of

[11] [1] to [9]. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an electrolyte membrane with a catalyst layer that can exhibit good fuel cell performance under high temperature and low humidity conditions. By using the electrolyte membrane with a catalyst layer of the present invention, good power generation performance can be obtained in a fuel cell. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view showing an example of a fuel cell cell that can be used in the present invention. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described in detail below, but the present invention is not limited to the embodiments described below and can be implemented with various modifications depending on the purpose and application.

[0012] The catalyst-layered electrolyte membrane according to an embodiment of the present invention has a configuration in which an anode catalyst layer and a cathode catalyst layer are arranged opposite each other with a solid polymer electrolyte membrane in between. The cathode catalyst layer contains a transition metal catalyst supported on conductive particles and a polymer electrolyte, and the BET specific surface area of ​​the cathode catalyst layer is 31 m². 2 The value is 1 / g or more. By applying such an electrolyte membrane with a catalyst layer, it is possible to manufacture fuel cells that exhibit good power generation performance under low temperature and high humidity conditions, and water electrolysis type hydrogen production equipment that has good electrolysis performance.

[0013] [Catalyst layer] In the catalyst-layered electrolyte membrane according to an embodiment of the present invention, a cathode catalyst layer is disposed on one side of the solid polymer electrolyte membrane, and an anode catalyst layer is disposed on the other side of the solid polymer electrolyte membrane. The catalyst layers used in the present invention will be described in detail below.

[0014] [Cathode catalyst layer] In the present invention, the cathode catalyst layer comprises a transition metal catalyst supported on conductive particles and a polymer electrolyte, and its BET specific surface area is 31 m². 2 It is characterized by being 1 / g or more.

[0015] The conductive particles contained in the cathode catalyst layer conduct electrons that flow in from the anode side to the cathode catalyst layer (these electrons are generated by an electrochemical oxidation reaction at the anode, conducted to the external circuit via the anode-side separator, and then flowed into the cathode catalyst layer via the cathode-side separator) to the transition metal catalyst surface, thereby completing a series of reactions and enabling the device to function as a power generation device by promoting an electrochemical reduction reaction.

[0016] Conductive particles are not particularly limited as long as they have electronic conductivity, but examples include carbon particles, metal particles, conductive oxide particles, conductive resin particles, semiconductor particles mainly composed of silicon or germanium, and mixtures thereof. Among these, conductive particles preferably include at least one selected from the group consisting of metal particles, metal oxide particles, and carbon particles, due to their high electronic conductivity. From the viewpoint of cost, dispersibility for easily obtaining uniform fine particles, and stability in the highly acidic environment of fuel cells, the conductive particles are more preferably carbon particles.

[0017] Examples of carbon particles include carbon black such as furnace black, acetylene black, Ketjen black, channel black, and lamp black; graphite (including carbon black that has been graphitized); activated carbon; carbon nanotubes; carbon nanofibers; and graphene. However, carbon black and graphite are preferred from the viewpoint of cost and stable supply.

[0018] Examples of metal particles include titanium, nickel, aluminum, zinc, cobalt, manganese, zirconium, cerium, yttrium, tungsten, and hafnium. Examples of metal oxides include titanium oxide, nickel oxide, aluminum oxide, zinc oxide, cobalt oxide, manganese oxide, zirconium oxide, cerium oxide, yttrium oxide, tungsten oxide, and hafnium oxide.

[0019] The transition metal catalyst included in the cathode catalyst layer is not particularly limited as long as it promotes the electrochemical reduction reaction of protons that have diffused from the anode through the electrolyte membrane, thereby producing water or hydrogen. When the electrolyte membrane with the catalyst layer is applied to a fuel cell, water and electricity are produced by the reduction reaction of protons with oxygen in the air. When applied to a water electrolysis type hydrogen generator, hydrogen is produced by reducing protons with external power. Specifically, the transition metal catalyst preferably includes at least one selected from the group consisting of platinum, gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium, cobalt, manganese, nickel, and alloys of two or more of these, but is not particularly limited. Among these, platinum, ruthenium, rhodium, palladium, osmium, iridium, and cobalt are preferred due to their high catalytic activity, and platinum is more preferred in terms of the balance of catalytic activity, safety, stability, and cost.

[0020] The polymer electrolyte contained in the cathode catalyst layer is not particularly limited as long as it is a polymer compound having proton conductivity, and hydrocarbon-based polymer electrolytes or fluorine-based polymer electrolytes can be used. Among these, fluorine-based polymer electrolytes are preferred from the viewpoint of gas permeability.

[0021] In fluorinated polymer electrolytes, a fluorinated polymer refers to a polymer having a main chain in which most or all of the hydrogen atoms in the alkyl and / or alkylene groups in the molecule are replaced with fluorine atoms.

[0022] Examples of fluorine-based polymer electrolytes include perfluorocarbon sulfonic acid polymers, perfluorocarbon phosphonic acid polymers, trifluorostyrene sulfonic acid polymers, trifluorostyrene phosphonic acid polymers, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymers, ethylene-tetrafluoroethylene copolymers having ionic groups, and polyvinylidene fluoride-perfluorocarbon sulfonic acid polymers.

[0023] Among these, perfluorocarbon sulfonic acid polymers are preferred from the viewpoint of heat resistance and chemical stability, and examples of such polymers include commercially available products such as "Nafion" (registered trademark) (manufactured by Chemours), "Flemion" (registered trademark) (manufactured by AGC Inc.), and "Acquivion" (registered trademark) (manufactured by Solvay Specialty Polymers).

[0024] The ion exchange capacity (IEC) of the polymer electrolyte contained in the cathode catalyst layer can be appropriately selected depending on the composition of the catalyst layer and the chemical structure of the polymer electrolyte. For example, when using a perfluorocarbon sulfonic acid polymer, a value of less than 1.50 meq / g is preferred, less than 1.40 meq / g is more preferred, and less than 1.30 meq / g is particularly preferred. The lower limit is preferably 0.40 meq / g or more.

[0025] Here, IEC refers to the molar amount of ionic groups introduced per unit dry weight of the polymer electrolyte, and a larger value indicates a greater amount of ionic groups introduced. In this invention, IEC is defined as the value obtained by neutralization titration.

[0026] In this invention, the BET specific surface area of ​​the cathode catalyst layer is 31 m². 2 It is above / g. Within this range, power generation and electrolysis performance can be improved under low-temperature and high-humidity conditions. The details of the mechanism are unknown, but it is presumed to be as follows.

[0027] Typically, the catalyst layer in fuel cells and water electrolysis hydrogen generators has a large number of fine pores to allow gas and water to permeate. (BET specific surface area: 31 m²) 2 Cathode catalyst layers with a concentration of 1 / g or higher tend to have many voids because the polymer electrolyte does not coat the surface of the conductive particles and transition metal catalyst, leaving gaps between the particles. When such a cathode catalyst layer is used, water produced at the cathode during the fuel cell reaction and associated water that diffuses from the anode to the cathode during the water electrolysis reaction are more likely to leak out.

[0028] Generally, in fuel cells and water electrolysis hydrogen generators under low-temperature and high-humidity conditions, since the electrolyte membrane with a catalyst layer contains a large amount of water, if the water discharge efficiency is low, there is a tendency for the pores of the catalyst layer to be blocked by water. Therefore, the oxygen gas required for the fuel cell reaction becomes difficult to diffuse to the cathode catalyst metal surface, and the power generation performance tends to decrease. In the case of a water electrolysis hydrogen generator, hydrogen generated by the water electrolysis reaction becomes difficult to be released from the cathode catalyst layer, so hydrogen gas tends to accumulate and the electrolysis performance decreases. By using an electrolyte membrane with a catalyst layer having a cathode catalyst layer with a BET specific surface area of 31 m 2 / g or more, the gas diffusion rate in the cathode catalyst layer is improved, so that the power generation performance and water electrolysis performance under low-temperature and high-humidity conditions can be improved.

[0029] Also, from the viewpoint of improving the power generation / electrolysis performance and the physical durability of the catalyst layer, the BET specific surface area of the cathode catalyst layer is preferably 150 m 2 / g or less, more preferably 100 m 2 / g or less, even more preferably 70 m 2 / g or less, particularly preferably 50 m 2 / g or less. Although the details of the mechanism are unclear, within this range, the polymer electrolyte that transports protons diffused from the anode to the catalyst metal surface in the catalyst layer is widely distributed on the catalyst metal and the surface of the conductive particles, so the diffusion of protons and the reduction reaction on the catalyst surface are accelerated, and as a result, it is presumed that the power generation / electrolysis performance is improved.

[0030] The BET specific surface area of the cathode catalyst layer is affected by the composition of the catalyst layer, the solvent composition of the catalyst layer coating solution and the coating solution preparation process, the thickness of the catalyst layer, the composition of the catalyst raw material, etc. Although the details of the mechanism are unclear, the BET specific surface area of the cathode catalyst layer generally has the following tendency. As a guide, it is advisable to appropriately adjust the design and manufacturing method so that the BET specific surface area becomes 31 m 2 / g or more.

[0031] The ratio (B / P) of the mass of the polymer electrolyte in the cathode catalyst layer to the total mass of the transition metal catalyst-supported conductive particles c), that is, if the value calculated from the formula (mass of polymer electrolyte) / (mass of conductive particles + mass of transition metal catalyst) is small, the BET specific surface area of ​​the catalyst layer will be large, and B / P c The larger the value, the smaller the BET specific surface area of ​​the catalyst layer tends to be. This is presumed to be because an increase in the amount of polymer electrolyte makes it easier to coat the surface of the metal catalyst and conductive particles.

[0032] The BET specific surface area also varies depending on the boiling point of the catalyst layer coating solvent and the coating thickness of the catalyst layer. Specifically, increasing the boiling point of the solvent or increasing the coating thickness tends to decrease the BET specific surface area by increasing the drying time. This is presumed to be because the solvent remains for a long time during the drying process, making it easier for the polymer electrolyte to coat the surface of the metal catalyst and conductive particles.

[0033] In the manufacturing process of the catalyst layer coating solution, a weak dispersion of metal catalysts or conductive particles tends to result in a large BET specific surface area of ​​the catalyst layer, while a strong dispersion tends to result in a smaller BET specific surface area. This is presumed to be because a strong dispersion makes it easier for the polymer electrolyte to coat the surface of the metal catalysts or conductive particles, while a weak dispersion makes it difficult for the polymer electrolyte to coat the surface of the metal catalysts or conductive particles.

[0034] Using conductive particles with a high BET specific surface area in the catalyst raw material, or increasing the proportion of conductive particles, tends to increase the BET specific surface area of ​​the cathode catalyst layer. Using conductive particles with a small BET specific surface area, or increasing the metal catalyst and decreasing the proportion of conductive particles, tends to decrease the BET specific surface area of ​​the catalyst layer. This is presumed to be because conductive particles generally have a large BET specific surface area, and therefore contribute significantly to the BET specific surface area of ​​the catalyst layer.

[0035] Furthermore, it is hypothesized that the physical durability of the catalyst layer is improved by the polymer electrolyte acting as a binder for the weakly interacting catalyst metal and conductive particles.

[0036] The loading rate of the transition metal catalyst in the conductive particles, i.e., the ratio calculated from the formula (mass of transition metal catalyst) / (mass of conductive particles + mass of transition metal catalyst), is preferably in the range of 20 to 70 mass%, more preferably in the range of 30 to 65 mass%, and particularly preferably in the range of 35 to 60 mass%.

[0037] In the cathode catalyst layer, the mass of the transition metal catalyst per unit area can be appropriately selected depending on the composition of the catalyst layer and the type of metal catalyst. For example, when using a platinum-supported carbon catalyst, 0.05 mg / cm³ is selected from the viewpoint of power generation and electrolysis performance. 2 The above is preferable, and 0.1 mg / cm³ 2 The above is more preferable, 0.2 mg / cm³ 2 The above is particularly preferable. Also, from a cost perspective, 1.0 mg / cm³ is preferable. 2 The following are preferable.

[0038] The above B / P c From the viewpoint of power generation and electrolysis performance, a value of 0.15 or higher is preferred, 0.20 or higher is more preferred, and 0.25 or higher is even more preferred. Furthermore, a value of 0.9 or lower is preferred, 0.8 or lower is more preferred, and 0.7 or lower is particularly preferred.

[0039] From the viewpoint of power generation and electrolysis performance, the thickness of the cathode catalyst layer is preferably 0.5 μm or more, more preferably 1 μm or more, and particularly preferably 3 μm or more. Furthermore, it is preferably 25 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0040] [Anode catalyst layer] The anode catalyst layer preferably includes an anode catalyst that oxidizes a fuel such as hydrogen or water to generate protons, and a polymer electrolyte that transports the generated protons to a solid polymer electrolyte membrane. The raw materials and composition can be appropriately selected depending on the application and operating conditions of the electrolyte membrane with catalyst layer.

[0041] For example, when used in fuel cell applications, a catalyst that oxidizes fuels such as hydrogen or methanol to promote the generation of protons and electrons can be used as the anode catalyst. In this case, a conductive particle catalyst supported with a transition metal can be used, similar to the cathode catalyst, and among these, a platinum-supported carbon catalyst is particularly suitable. The composition of the metal and support in the catalyst particles, the type and properties of the polymer electrolyte, and the ratio of catalyst particles to polymer electrolyte, as well as other components of the overall anode catalyst layer, can preferably be the same as those of the cathode catalyst layer, but they do not necessarily have to be all the same or similar, and can be adjusted as appropriate according to operating conditions, etc.

[0042] When applied to a water electrolysis hydrogen generator, a catalyst can be used that reduces water using external power as an energy source and promotes the production of oxygen and protons. In this case, from the viewpoint of electrolysis performance, it is preferable to include iridium as the anode catalyst.

[0043] As iridium-containing catalysts, zero-valent iridium, iridium oxide, iridium carbide, iridium nitride, etc., can be used, but iridium oxide is preferred because it can maintain good electrolytic performance for a longer period of time. The iridium-containing catalyst is preferably in the form of particles.

[0044] The iridium-containing catalyst may also be catalyst-supported particles supported on a support made of a metal oxide such as titanium oxide, tin oxide, tantalum oxide, niobium oxide, zirconium oxide, or tungsten oxide. Since the anode in a water electrolysis hydrogen generator is in a high-potential environment, a support with relatively high electrochemical oxidation resistance is preferred. In this respect, the above-mentioned metal oxides are preferred because they have relatively high electrochemical oxidation resistance.

[0045] The iridium content in the anode catalyst layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total elemental amount of all metal catalysts contained in the anode catalyst layer (100% by mass). The upper limit is preferably 100% by mass or less.

[0046] The anode catalyst layer may further contain, in addition to iridium, platinum, gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium, cobalt, nickel, or alloys thereof. In water electrolysis hydrogen generators, hydrogen produced at the cathode mixes with oxygen produced at the anode by back diffusion, which can create a risk of explosion. However, since the aforementioned metals function as catalysts for producing water from hydrogen and oxygen, they are preferable because they reduce the risk of explosion. Platinum or palladium is preferable due to their high hydrogen decomposition capacity, and platinum is particularly preferable. Examples of forms in which the aforementioned metals are contained include zero-valent, oxides, carbides, and nitrides. Among these, zero-valent forms are preferred.

[0047] When the anode catalyst layer contains the aforementioned metal element in combination with iridium, the content of the aforementioned metal element is preferably in the range of 1 to 90 parts by mass, more preferably in the range of 5 to 80 parts by mass, and particularly preferably in the range of 10 to 50 parts by mass, per 100 parts by mass of iridium.

[0048] In the anode catalyst layer, the mass of iridium element per unit area is 0.2 to 2.0 mg / cm². 2 A range of 0.4 to 1.5 mg / cm³ is preferred. 2 A range of 0.6 to 1.3 mg / cm³ is more preferable. 2 The range is particularly preferable.

[0049] The anode catalyst layer preferably contains a polymer electrolyte. The same polymer electrolyte as that used in the cathode catalyst layer can be suitably used. Specifically, hydrocarbon-based polymer electrolytes and fluorine-based polymer electrolytes can be used. Fluorine-based polymer electrolytes are preferred from the viewpoint of gas permeability, and perfluorocarbon sulfonic acid polymers are more preferred from the viewpoint of heat resistance and chemical stability.

[0050] When the anode catalyst layer for a water electrolysis hydrogen generator containing iridium contains a polymer electrolyte, the ratio of the mass of the polymer electrolyte to the mass of the catalyst (P / B) a ), that is, (mass of polymer electrolyte) / (mass of iridium catalyst) is preferably 0.05 or higher, more preferably 0.07 or higher, and particularly preferably 0.1 or higher, from the viewpoint of electrolytic performance. Furthermore, it is preferably less than 0.5, more preferably less than 0.4, even more preferably less than 0.3, and particularly preferably less than 0.25.

[0051] From the viewpoint of electrolytic performance, the thickness of the anode catalyst layer is preferably 0.5 μm or more, more preferably 1 μm or more, and particularly preferably 3 μm or more. Furthermore, from the viewpoint of the diffusibility of oxygen gas generated in the anode and physical stability (such as cracking during operation), the above thickness is preferably 25 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0052] [Solid polymer electrolyte membrane] The solid polymer electrolyte membrane contains a polymer electrolyte. In the present invention, the solid polymer electrolyte membrane means a membrane containing a polymer electrolyte in an amount of 50% by mass or more based on 100% by mass of the total solid content of the solid polymer electrolyte membrane. The polymer electrolyte content is more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0053] As the polymer electrolyte contained in the solid polymer electrolyte membrane, known polymer electrolytes such as fluorine-based polymer electrolytes and hydrocarbon-based polymer electrolytes can be used. In the present invention, it is preferable that the solid polymer electrolyte membrane contains a hydrocarbon-based polymer electrolyte due to its low gas permeability.

[0054] When using fluorine-based polymer electrolytes, perfluorocarbon sulfonic acid polymers are preferred from the viewpoint of heat resistance and chemical stability, as mentioned above. Examples of such polymers include commercially available products such as "Nafion" (registered trademark) (manufactured by Chemours), "Flemion" (registered trademark) (manufactured by AGC Inc.), and "Acquivion" (registered trademark) (manufactured by Solvay Specialty Polymers).

[0055] Examples of hydrocarbon-based polymer electrolytes include hydrocarbon polymers having ionic groups. A hydrocarbon polymer is defined as a polymer having a main chain whose main constituent units are hydrocarbons. Among the above hydrocarbon polymers, aromatic hydrocarbon polymers having aromatic rings in the main chain are preferred. In other words, aromatic hydrocarbon polymer electrolytes are preferred among hydrocarbon-based polymer electrolytes.

[0056] Specific examples of aromatic hydrocarbon polymers include polymers having a structure and aromatic ring selected from polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene polymers, polyarylene ketone, polyether ketone, polyarylene phosphine oxide, polyetherphosphine oxide, polybenzoxazole, polybenzthiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, and polyimide sulfone as the main chain.

[0057] Furthermore, the term "polysulfone" refers to a general term for structures having sulfone bonds in their molecular chains, "polyethersulfone" refers to a general term for structures having both ether and sulfone bonds in their molecular chains, and "polyetherketone" refers to a general term for structures having both ether and ketone bonds in their molecular chains. Aromatic hydrocarbon polymers may have multiple of these structures.

[0058] Polyetherketone polymers are particularly preferred as aromatic hydrocarbon polymers. Examples of polyetherketone polymers include polyetherketone, polyetherketoneketone, polyetheretherketone, polyetheretherketoneketone, and polyetherketoneetherketoneketone.

[0059] Furthermore, among aromatic hydrocarbon polymers, block copolymers are preferred. Here, a block copolymer refers to a block copolymer of a segment containing structural units that contain ionic groups and a segment containing structural units that do not contain ionic groups.

[0060] The above-mentioned ionic group may be any ionic group having either cation exchange ability or anion exchange ability, but in the present invention, it is preferable to use a proton-exchangeable ionic group. Examples of such functional groups include sulfonic acid groups, sulfonimide groups, sulfate groups, phosphonic acid groups, phosphoric acid groups, carboxylic acid groups, ammonium groups, phosphonium groups, and amino groups. Two or more types of ionic groups can be included in the polymer. Among these, sulfonic acid groups, sulfonimide groups, and sulfate groups are preferred because they have excellent power generation and electrolysis performance, and sulfonic acid groups are more preferred from the viewpoint of raw material cost.

[0061] As described above, it is preferable to use an aromatic hydrocarbon block copolymer as the polymer electrolyte, and more preferably a polyetherketone block copolymer. As the polyetherketone block copolymer, it is particularly preferable to have a segment containing a constituent unit (S1) containing an ionic group as described below, and a segment containing a constituent unit (S2) that does not contain an ionic group.

[0062] [ka]

[0063] In general formula (S1), Ar 11 ~Ar 14 represents any divalent arylene group, Ar 11 and / or Ar 12 It contains an ionic group, Ar 13 and Ar 14 It may or may not contain an ionic group. 11 ~Ar 14 The group may be substituted as desired, and two or more types of arylene groups may be used independently of each other. * represents a bonding site with the general formula (S1) or other constituent units.

[0064] [ka]

[0065] In general formula (S2), Ar 15 ~Ar 18 represents any divalent arylene group, which may be optionally substituted, but does not contain an ionic group. 15 ~Ar 18 Two or more arylene groups may be used independently of each other. * represents a bonding site with the general formula (S2) or other constituent units.

[0066] Here, Ar 11 ~Ar 18Preferred divalent arylene groups include, but are not limited to, hydrocarbon arylene groups such as phenylene groups, naphthylene groups, biphenylene groups, and fluoroorangeyl groups, and heteroarylene groups such as pyridinediyl, quinoxalinediyl, and thiophenediyl. Here, "phenylene group" can be of three types depending on the location of the bond site between the benzene ring and other structural units: o-phenylene group, m-phenylene group, and p-phenylene group. In this specification, unless otherwise specified, these are used as a general term. The same applies to other divalent arylene groups such as "naphthylene group" and "biphenylene group". 11 ~Ar 12 Preferably, it is a phenylene group containing a phenylene group and an ionic group, most preferably a p-phenylene group containing a p-phenylene group and an ionic group. 13 ~Ar 14 From the viewpoint of proton conductivity, those substituted with ionic groups are preferably used. They may also be substituted with functional groups other than ionic groups, but unsubstituted ones are also preferable in terms of chemical stability and physical durability, and can be appropriately selected depending on the application and usage conditions of the catalyst layer-equipped electrolyte membrane. 15 ~Ar 18 Although it may be substituted with groups other than ionic groups, it is more preferable to be unsubstituted in terms of proton conductivity, chemical stability, and physical durability.

[0067] The ion exchange capacity (IEC) of the polymer electrolyte constituting the solid polymer electrolyte membrane is preferably 0.5 meq / g or more and 3.5 meq / g or less. From the viewpoint of obtaining good electrolysis performance and good power generation performance, in the case of hydrocarbon-based polymer electrolytes, the IEC is more preferably 1.0 meq / g or more and 3.5 meq / g or less, even more preferably 1.4 meq / g or more and 3.0 meq / g or less, and particularly preferably 1.6 meq / g or more and 2.7 meq / g or less. In the case of fluorine-based polymer electrolytes, the IEC is more preferably 0.5 meq / g or more and 2.0 meq / g or less, even more preferably 0.7 meq / g or more and 1.7 meq / g or less, and particularly preferably 0.8 meq / g or more and 1.5 meq / g or less.

[0068] The hydrocarbon-based polymer electrolyte content is preferably 60% by mass or more, more preferably 75% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass, based on 100% by mass of the total mass of the polymer electrolyte contained in the solid polymer electrolyte membrane.

[0069] The thickness of the solid polymer electrolyte membrane is not particularly limited and can be appropriately selected depending on the application and operating conditions. For example, when used in fuel cell applications, from the viewpoint of power generation performance and durability, a thickness of 2 μm or more is preferred, 3 μm or more is more preferred, and 4 μm or more is even more preferred. A thickness of 25 μm or less is preferred, 20 μm or less is more preferred, 15 μm or less is even more preferred, and 10 μm or less is particularly preferred. When used in water electrolysis hydrogen generators, from the viewpoint of electrolysis performance and durability, a thickness of 25 μm or more is preferred, 30 μm or more is more preferred, and 40 μm or more is even more preferred. A thickness of 250 μm or less is preferred, 200 μm or less is more preferred, 150 μm or less is even more preferred, and 120 μm or less is particularly preferred.

[0070] A solid polymer electrolyte membrane may be composed of multiple layers. When a solid polymer electrolyte membrane is composed of multiple layers, the polymer electrolytes contained in each layer may have the same or different structures. Examples of the multiple layers include a laminated configuration of a layer containing a hydrocarbon-based polymer electrolyte and a layer containing a fluorine-based polymer electrolyte, and a configuration in which a composite layer containing a porous substrate and a polymer electrolyte has a non-composite layer containing the polymer electrolyte on one or both sides but not the porous substrate. The composite layer is a layer in which the pores of the porous substrate are filled with the polymer electrolyte. Examples of porous substrates include woven fabrics, nonwoven fabrics, porous films, and mesh fabrics.

[0071] The thickness ratio of the composite layer is preferably 10-90%, more preferably 20-80%, and particularly preferably 30-70%, with the thickness of the solid polymer electrolyte membrane being 100%. Here, the thickness of the composite layer refers to the thickness of the porous substrate.

[0072] The solid polymer electrolyte membrane may contain various additives, such as antioxidants, surfactants, radical scavengers, hydrogen peroxide decomposers, non-electrolyte polymers, elastomers, fillers, etc., as long as they do not impair the effects of the present invention.

[0073] Solid polymer electrolyte membranes can be appropriately selected according to the raw materials, composition, film thickness, size, etc. For example, they can be manufactured by coating a polymer electrolyte solution onto a film-forming substrate and drying it. Examples of such film-forming substrates include polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT), polycarbonate (PC), polyetherimide (PEI), polyphenylene sulfide (PPS), polyimide (PI), polyamideimide (PAI), polystyrene (PS), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroalkoxy fluororesin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and polyhexafluoropropylene. Among these, polyester is preferred from the viewpoint of chemical resistance, heat resistance, and cost, and PET is more preferred. The film-forming substrate is ultimately peeled off and may be subjected to release treatment or antiblocking treatment as necessary. The thickness of the film-forming substrate is preferably 30 to 1,000 μm, more preferably 50 to 800 μm, and particularly preferably 100 to 600 μm.

[0074] As the coating method, known coating methods such as knife coating, direct roll coating, Meyer bar coating, gravure coating, reverse coating, air knife coating, spray coating, brush coating, dip coating, die coating, vacuum die coating, curtain coating, flow coating, spin coating, screen printing, and inkjet printing can be applied.

[0075] [Middle class] The electrolyte membrane with a catalyst layer according to an embodiment of the present invention may include an intermediate layer between the solid polymer electrolyte membrane and the catalyst layer. The intermediate layer is not particularly limited and various functional layers can be included. For example, a protective layer (for protecting the solid polymer electrolyte membrane), an adhesive layer (for strengthening the adhesion between the solid polymer electrolyte membrane and the catalyst layer), and a gas transfer suppression layer (for decomposing or capturing gases such as hydrogen, oxygen, and hydrogen peroxide) can be included. From the viewpoint of durability, it is preferable to place the intermediate layer between the solid polymer electrolyte membrane and the cathode catalyst layer.

[0076] The intermediate layer may have a different composition from both the solid polymer electrolyte membrane and the adjacent catalyst layer, and its detailed composition is not particularly limited. However, from the viewpoint of power generation / electrolysis performance and durability, it is preferable that it contains a polymer electrolyte and conductive particles, and more preferably that it does not contain a transition metal catalyst.

[0077] The polymer electrolyte and conductive particles included in the intermediate layer can be the same as those used in the preferred example of the cathode catalyst layer described above, but are not particularly limited.

[0078] When an intermediate layer is provided, its thickness is preferably in the range of 0.1 to 30 μm, more preferably in the range of 0.5 to 20 μm, and particularly preferably in the range of 1 to 15 μm.

[0079] [Method for manufacturing electrolyte membranes with catalyst layer] An electrolyte membrane with a catalyst layer according to an embodiment of the present invention can be obtained, for example, by laminating an anode catalyst layer and a cathode catalyst layer onto a solid polymer electrolyte membrane. Alternatively, the electrolyte membrane with a catalyst layer according to the present invention can be manufactured in the assembly process of a membrane electrode assembly described later. The latter embodiment will be described in detail later.

[0080] From the viewpoint of adhesion between the solid polymer electrolyte membrane and the catalyst layer, it is preferable that both the anode catalyst layer and the cathode catalyst layer are laminated on the solid polymer electrolyte membrane.

[0081] Methods for laminating a catalyst layer onto a solid polymer electrolyte membrane include, for example, a coating method, a transfer method, or a combination of the coating method and the transfer method.

[0082] As for the coating method, similar to the method of manufacturing the solid polymer electrolyte membrane by coating, various known coating methods can be applied to the catalyst layer coating liquid using the solid polymer electrolyte membrane as the coating substrate. As for the transfer method, one example is a method in which a decal sheet with the catalyst layer laminated on a transfer substrate and the solid polymer electrolyte membrane are stacked and heated and pressed together.

[0083] As for the manufacturing method of the decal sheet, similar to the method of manufacturing a solid polymer electrolyte membrane by coating, various known coating methods can be applied to the catalyst layer coating liquid using the decal substrate as the coating substrate. The decal substrate can be appropriately selected from the same film-forming substrates as those used in the manufacturing of the solid polymer electrolyte membrane, but since the catalyst layer is fixed to the solid polymer electrolyte membrane and peeled off from the decal substrate, fluorine-based decal substrates such as PTFE, PVdF, ETFE, PFA, and FEP, which tend to have low peel strength, are preferred, and PTFE is more preferred from the viewpoint of solvent resistance and cost.

[0084] In the electrolyte membrane with a catalyst layer according to an embodiment of the present invention, the thicknesses of the solid polymer electrolyte membrane, the cathode catalyst layer, and the anode catalyst layer are as described above, but it is preferable to adjust the relationship between these thicknesses from the viewpoint of maintaining good performance for a longer period of time. For example, it is preferable that the thickness of the cathode catalyst layer and / or the anode catalyst layer be 25% or less relative to 100% of the thickness of the solid polymer electrolyte membrane. More specifically, the thickness of the cathode catalyst layer and / or the anode catalyst layer is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less, relative to 100% of the thickness of the solid polymer electrolyte membrane. The lower limit is preferably 1% or more. The thickness of the cathode catalyst layer is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less, relative to 100% of the thickness of the solid polymer electrolyte membrane. The lower limit is preferably 1% or more.

[0085] [Membrane Electrode Assembly (MEA)] An electrolyte membrane with a catalyst layer according to an embodiment of the present invention becomes a membrane electrode assembly when electrode substrates are arranged on both sides thereof. That is, the membrane electrode assembly has an anode catalyst layer and an anode electrode substrate on one side of the solid polymer electrolyte membrane, and a cathode catalyst layer and a cathode electrode substrate on the other side.

[0086] The electrode substrate (which may also serve as the gas diffusion layer) is primarily intended for uniform diffusion of gas or water into the catalyst layer and conduction of electrons, and is composed of a conductive material. As the electrode substrate, porous substrates such as metal or carbon can be used. Examples of metal porous substrates include metal nonwoven fabric, metal fiber sintered body, metal powder sintered body, and metal foam sintered body. Examples of carbon porous substrates include carbon felt, carbon paper, carbon cloth, and graphite particle sintered body, but carbon paper is preferred from the viewpoint of material cost and conductivity.

[0087] The anode electrode substrate can be appropriately selected depending on the application. For example, in fuel cell applications, a porous carbon substrate is preferred from the viewpoint of material cost and conductivity, and carbon paper is particularly preferred. In water electrolysis hydrogen generators, a porous metal substrate is preferably used because it has excellent corrosion resistance in environments such as high potential, in the presence of oxygen, and in strong acidity. From the above viewpoint, as the metal constituting the porous metal substrate, titanium, aluminum, nickel, stainless steel, and alloys mainly composed of at least one of these metals are preferred, and titanium and alloys mainly composed of titanium are particularly preferred.

[0088] As the cathode electrode substrate, a carbon porous substrate is preferred from the viewpoint of material cost and conductivity, and carbon paper is particularly preferred.

[0089] In a membrane electrode assembly, the anode catalyst layer and the cathode catalyst layer can be laminated on the electrode substrate, either individually or in combination. During the membrane electrode assembly process, the electrode substrate with the laminated catalyst layer and the solid polymer electrolyte membrane are arranged, resulting in a configuration where the anode catalyst layer and the cathode catalyst layer are positioned opposite each other with the solid polymer electrolyte membrane in between. In other words, the electrolyte membrane with the catalyst layer is completed during the membrane electrode assembly process, and the present invention includes this embodiment.

[0090] In the above embodiment, the anode catalyst layer and the cathode catalyst layer may be laminated on the electrode substrate, but depending on the type of electrode substrate, sufficient adhesion to the catalyst layer may not be obtained, so it is preferable to select the appropriate electrode substrate according to its type. For example, since a carbon porous substrate has relatively good adhesion to the catalyst layer, the cathode catalyst layer may be laminated on a suitable cathode electrode substrate made of a carbon porous substrate, and the anode catalyst layer may be laminated on a solid polymer electrolyte membrane. As a method for laminating the catalyst layer onto the electrode substrate, the coating method or transfer method described above can be used.

[0091] [Examples of application] The catalyst-layered electrolyte membrane and the membrane electrode assembly using the same according to embodiments of the present invention can be applied to fuel cells, water electrolysis hydrogen generators, electrochemical hydrogen compressors, redox flow batteries, and the like. Among these, application to fuel cells and water electrolysis hydrogen generators is preferred. An example of application to fuel cells will be described in detail below, but the present invention is not limited to these.

[0092] [Fuel cell and fuel cell] The fuel cell in this invention includes a polymer electrolyte membrane. The fuel cell is divided internally into a cathode (composed of a cathode catalyst layer and a cathode electrode substrate) and an anode (composed of an anode catalyst layer and an anode electrode substrate) by a polymer electrolyte membrane.

[0093] Figure 1 is a schematic cross-sectional view showing an example of a fuel cell cell that can be used in the present invention. The fuel cell cell 1 is divided into a cathode and an anode by a solid polymer electrolyte membrane 10. Here, the cathode is composed of a cathode catalyst layer 21 and a cathode electrode substrate 31, and the anode is composed of an anode catalyst layer 22 and an anode electrode substrate 32. These are sandwiched from both sides by separators 41 and 42.

[0094] A fuel cell system typically consists of multiple fuel cell cells arranged in a grid, with the cathode as the positive electrode and the anode as the negative electrode, generating electricity and supplying power to external devices. The basic components of a fuel cell include a fuel supply unit that supplies fuel such as hydrogen to the fuel cell cells, an oxidant gas supply unit that supplies an oxidant gas such as air to the fuel cell cells, a fuel discharge unit that discharges excess fuel after power generation, an oxidant gas discharge unit that discharges the generated oxidant gas containing water, and a power supply unit that supplies the generated electricity to external devices.

[0095] [Fuel cell operation method] The fuel cell operation method in the present invention is performed using the fuel cell cell and fuel cell device described above. That is, the fuel cell operation method according to the embodiment of the present invention is a fuel cell operation method in which a fuel cell cell, whose interior is divided into a cathode and an anode by a solid polymer electrolyte membrane, is supplied with a fuel such as hydrogen and an oxidizing gas such as air, and electricity is generated by an electrochemical reaction to produce water in the cathode. Both the cathode catalyst layer constituting the cathode and the anode catalyst layer constituting the anode contain a transition metal catalyst such as platinum and conductive particles such as carbon black as catalysts. The solid polymer electrolyte membrane, cathode catalyst layer and anode catalyst layer in this method can preferably be those described above. [Examples]

[0096] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The various measurement conditions are as follows.

[0097] (1) Molecular weight of polymer The number-average molecular weight and weight-average molecular weight of polymers were measured by GPC. A Tosoh HLC-8022GPC gel permeation chromatograph was used. Two Tosoh TSK gel SuperHM-H columns (6.0 mm inner diameter, 15 cm length) were used as GPC columns. Measurements were performed in N-methyl-2-pyrrolidone solvent (containing 10 mmol / L lithium bromide) at a flow rate of 0.2 mL / min, and the number-average molecular weight and weight-average molecular weight were determined by converting to standard polystyrene equivalents.

[0098] (2) Ion exchange capacity (IEC) The measurement was performed using the neutralization titration method described in 1) to 4) below. Three measurements were taken, and the average value was calculated. 1) After removing moisture from the solid polymer electrolyte membrane that had been proton-substituted and thoroughly washed with pure water, it was vacuum-dried at 100°C for more than 12 hours, and the dry weight was determined. 2) 50 mL of 5 wt% sodium sulfate aqueous solution was added to the solid polymer electrolyte membrane and allowed to stand for 12 hours to perform ion exchange. 3) The resulting sulfuric acid was titrated using a 0.01 mol / L sodium hydroxide aqueous solution. A commercially available 0.1 w / v% titration phenolphthalein solution was added as an indicator, and the endpoint was defined as the point at which the solution turned a pale reddish-purple. 4) IEC was calculated using the following formula. IEC (meq / g) = [Concentration of sodium hydroxide solution (mmol / ml) × Droplet volume (ml)] / Dry weight of sample (g).

[0099] (3) Measurement of the thickness of the solid polymer electrolyte membrane and catalyst layer The cross-sections of the solid polymer electrolyte membrane and each catalyst layer were observed using a scanning electron microscope (SEM) according to the following conditions, and the thicknesses of the solid polymer electrolyte membrane, anode catalyst layer, and cathode catalyst layer were measured from the obtained images. • Equipment: Field emission scanning electron microscope (FE-SEM) S-4800 (Manufactured by Hitachi High-Technologies) • Acceleration voltage: 2.0kV • Pretreatment: Cross-sectional samples prepared using the BIB method were coated with Pt and then measured. • BIB method: A cross-sectional sample preparation device using an argon ion beam. A shielding plate is placed directly above the sample, and an argon broad ion beam is irradiated from above to perform etching, thereby creating an observation surface and an analysis surface (cross-section).

[0100] (4) Evaluation of fuel cell performance To evaluate the fuel cell performance of the electrolyte membrane with a catalyst layer, a membrane electrode assembly was fabricated according to the following procedure.

[0101] [Membrane electrode assembly] The electrolyte membranes with catalyst layers prepared in the examples and comparative examples were cut into 5 cm squares. Two 5 cm square pieces of commercially available SGL gas diffusion electrode 24BCH were prepared, and the electrolyte membranes with catalyst layers were sandwiched between them to create a membrane electrode assembly.

[0102] [Fuel cell operation method] The membrane electrode assembly prepared by the above method was placed in the JARI standard cell "Ex-1" (electrode area 25 cm²) manufactured by Eiwa Co., Ltd. 2 The device was set to a specific configuration and the cell temperature was set to 50°C. Hydrogen gas was supplied to the anode in an amount that resulted in a gas utilization rate of 70%, and air was supplied to the cathode in an amount that resulted in a gas utilization rate of 60%, both adjusted to a relative humidity of 100% RH, at atmospheric pressure, with a current density of 1.0 A / cm². 2 Fuel cell operation was performed. The electromotive force (V) generated between the anode and cathode was defined as the power generation performance. Note that the power generation performance was low, resulting in a current density of 1.0 A / cm². 2 If the electromotive force (V) becomes 0, it is indicated as "No power generation" in Table 1 below.

[0103] (5) BET specific surface area measurement method A portion of the cathode catalyst layer, prepared as a cathode catalyst transfer sheet, was cut out and scraped into a powder using a PP chemical spoon. The powder was then dried in a vacuum dryer at 25°C in vacuo for 16 hours to remove residual solvent and adsorbed water. Next, the sample was packed into a dedicated cell, and after pretreatment according to the following conditions, the sample mass was measured and the BET specific surface area of ​​the catalyst layer was determined. • Equipment: Gas adsorption evaluation system BELSORP-mini II (Microtrac, manufactured by Bell) • Measurement temperature: 77K (liquid nitrogen temperature) • Adsorbent: N2 gas • Saturated vapor pressure: This value was set to be the same as the measured atmospheric pressure for each measurement. • Adsorption cross-section: 0.162 nm 2 (Molecular occupied cross-sectional area of ​​N2 molecule) • Pre-treatment conditions: After packing the sample into a dedicated cell, it was connected to a dedicated pre-treatment device, BELPREP VAC II (manufactured by Microtrac-Bel). The sample was dried at 23°C in vacuo for 5 hours to remove moisture adsorbed on the sample and the inner wall of the dedicated cell, and the inside of the cell was filled with dry N2 gas to remove gases other than N2 and volatile components from the measurement system. • Measurement conditions: Adsorption isotherms were measured at 11 points including the above upper and lower limits, with one lower limit being a relative pressure (p / p0) greater than 0.045 and less than 0.055, and one upper limit being between 0.28 and less than 0.35, ensuring even spacing between measurement points. An analysis based on BET theory was performed on these adsorption isotherms to calculate the BET specific surface area.

[0104] (6) Method for measuring the mass of transition metal catalysts per unit area The amount of catalyst per unit area in the catalyst layer was measured according to the following conditions. • Equipment: X-ray fluorescence analyzer JSX-1000S (manufactured by JEOL) • Measurement atmosphere: Air • Collimator: 9mmφ • Measurement time: 90 seconds • Tube voltage: 50.0kV • Tube current: Automatically adjusted so that the dead time was between 20 and 25 seconds within the range of 0.0 to 1.0 mA. If the dead time was between 0 and 20 seconds at a tube current of 1.0 mA, the measurement was taken at 1.0 mA. The fluorescence X-ray intensity was converted to the content of each element using the instrument's internal standards.

[0105] [Synthesis Example 1] (Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP), represented by the chemical formula (G1) below) In a 500 mL flask equipped with a stirrer, thermometer, and distillation tube, 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate, and 0.50 g of p-toluenesulfonic acid monohydrate were charged and dissolved. The mixture was then kept warm and stirred at 78-82°C for 2 hours. The internal temperature was then gradually increased to 120°C, and the mixture was heated until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling the reaction mixture to room temperature, it was diluted with ethyl acetate, and the organic layer was washed with 100 mL of 5% potassium carbonate aqueous solution. After liquid-liquid extraction, the solvent was removed by distillation. 80 mL of dichloromethane was added to the residue to precipitate crystals, which were filtered and dried to obtain 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane, represented by the following chemical formula (G1). GC analysis of this crystal revealed that it consisted of 99.9% 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane and 0.1% 4,4'-dihydroxybenzophenone. The purity was 99.9%.

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[0107] [Synthesis Example 2] (Synthesis of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone, represented by the chemical formula (G2) below) 109.1 g of 4,4'-difluorobenzophenone (Sigma-Aldrich Japan reagent) was reacted in 150 mL of fuming sulfuric acid (50% SO3) (Fujifilm Wako Pure Chemical Industries reagent) at 100°C for 10 hours. Then, the mixture was gradually added to a large volume of water, neutralized with sodium hydroxide, and 200 g of sodium chloride (NaCl) was added to precipitate the product. The precipitate was filtered and recrystallized in an aqueous ethanol solution to obtain disodium-3,3'-disulfonate-4,4'-difluorobenzophenone, represented by the following chemical formula (G2). The purity was 99.3%.

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[0109] [Synthesis Example 3] (Synthesis of nonionic oligomer a1 represented by the general formula (G3) below) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 16.59 g of potassium carbonate (Sigma-Aldrich Japan reagent, 120 mmol), 25.83 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and 20.3 g of 4,4'-difluorobenzophenone (Sigma-Aldrich Japan reagent, 93 mmol) were added. After nitrogen purging, 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene were added. Dehydration was performed at 150°C, followed by heating to remove the toluene, and polymerization was carried out at 170°C for 3 hours. Reprecipitation and purification with a large amount of methanol were performed to obtain the terminal hydroxyl form of nonionic oligomer a1. The number-average molecular weight of this terminal hydroxyl form of nonionic oligomer a1 was 10,000.

[0110] In a 500 mL three-necked flask equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 1.1 g of potassium carbonate (Sigma-Aldrich Japan reagent, 8 mmol) and 20.0 g (2 mmol) of the terminal hydroxyl form of the nonionic oligomer a1 were added. After purging the apparatus with nitrogen, 100 mL of NMP and 30 mL of toluene were added, and the mixture was dehydrated at 100 °C, followed by heating to remove the toluene. Furthermore, 2.2 g of hexafluorobenzene (Sigma-Aldrich Japan reagent, 12 mmol) was added, and the reaction was carried out at 105 °C for 12 hours. Reprecipitation and purification with a large amount of isopropyl alcohol were performed to obtain nonionic oligomer a1 (terminal: fluoro group) represented by the following general formula (G3). The number-average molecular weight was 11,000.

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[0112] [Synthesis Example 4] (Synthesis of ionic oligomer a2 represented by the general formula (G4) below) In a 2,000 mL SUS polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 27.6 g of potassium carbonate (Sigma-Aldrich Japan reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.3 g of 4,4'-biphenol (Sigma-Aldrich Japan reagent, 50 mmol), 39.3 g (93 mmol) of disodium-3,3'-disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2, and 17.9 g of 18-crown-6 (Fujifilm Wako Pure Chemical Industries, Ltd., 82 mmol) were added. After nitrogen purging, 300 mL of NMP and 100 mL of toluene were added, dehydration was performed at 150 °C, the temperature was increased to remove the toluene, and polymerization was carried out at 170 °C for 6 hours. Reprecipitation purification with a large amount of isopropyl alcohol yielded the ionic oligomer a2 (terminal: hydroxyl group) represented by the following general formula (G4). The number-average molecular weight was 16,000. In general formula (G4), M represents a hydrogen atom, Na, or K.

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[0114] [Synthesis Example 5] (Synthesis of polyetherketone block copolymers) In a 2,000 mL stainless steel polymerization apparatus equipped with a stirrer, nitrogen inlet tube, and Dean-Stark trap, 16 g of ionic oligomer a2 and 11 g of nonionic oligomer a1 were added, and NMP was added to bring the total amount of oligomers to 7 wt%, and the reaction was carried out at 105°C for 24 hours.

[0115] The material was reprecipitated in a large amount of isopropyl alcohol / NMP mixture (mass ratio 2 / 1), and the resulting precipitate was collected by filtration and washed with a large amount of isopropyl alcohol to obtain block copolymer b1. The weight-average molecular weight of this polyetherketone-based block copolymer was 340,000, and the ion exchange capacity (IEC) was 2.1 meq / g.

[0116] [Synthesis Example 6] (Synthesis of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate, represented by the chemical formula (G5) below) 245 g (2.1 mol) of chlorosulfonic acid was placed in a 3 L three-necked flask equipped with a stirrer and condenser, followed by 105 g (420 mmol) of 2,5-dichlorobenzophenone. The mixture was reacted in a 100°C oil bath for 8 hours. After the specified time, the reaction mixture was slowly poured onto 1,000 g of crushed ice and extracted with ethyl acetate. The organic layer was washed with saline solution, dried over magnesium sulfate, and the ethyl acetate was removed by distillation to obtain pale yellow crude crystals of 3-(2,5-dichlorobenzoyl)benzenesulfonic acid chloride. The crude crystals were not purified and were used directly in the next step.

[0117] 41.1 g (462 mmol) of 2,2-dimethyl-1-propanol (neopentyl alcohol) was added to 300 mL of pyridine and cooled to approximately 10°C. The crude crystals obtained above were gradually added over approximately 30 minutes. After the entire amount was added, the mixture was stirred and reacted for another 30 minutes. After the reaction, the reaction solution was poured into 1,000 mL of hydrochloric acid solution, and the precipitated solid was collected. The obtained solid was dissolved in ethyl acetate, washed with sodium bicarbonate aqueous solution and saline solution, dried over magnesium sulfate, and the ethyl acetate was removed by distillation to obtain crude crystals. These were recrystallized with methanol to obtain white crystals of 3-(2,5-dichlorobenzoyl)benzenesulfonic acid neopentyl, represented by the following chemical formula (G5).

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[0119] [Synthesis Example 7] (Synthesis of oligomers that do not contain ionic groups represented by the general formula (G6) below) A 1 L three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube, and a three-way stopcock for nitrogen introduction contained 49.4 g (0.29 mol) of 2,6-dichlorobenzonitrile, 88.4 g (0.26 mol) of 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and 47.3 g (0.34 mol) of potassium carbonate. After purging with nitrogen, 346 mL of sulfolane and 173 mL of toluene were added and the mixture was stirred. The flask was placed in an oil bath and heated to 150 °C under reflux. The water produced by the reaction was azeotropically mixed with toluene and removed from the system using a Dean-Stark tube. After about 3 hours, almost no water was produced. After removing most of the toluene by gradually increasing the reaction temperature, the reaction was continued at 200 °C for 3 hours. Next, 12.3 g (0.072 mol) of 2,6-dichlorobenzonitrile was added, and the reaction was continued for another 5 hours.

[0120] After the resulting reaction solution was allowed to cool, it was diluted with 100 mL of toluene. The precipitate of the by-product inorganic compound was removed by filtration, and the filtrate was added to 2 L of methanol. The precipitated product was filtered off, recovered, dried, and dissolved in 250 mL of tetrahydrofuran. This was reprecipitated in 2 L of methanol to obtain 107 g of the target oligomer represented by the following general formula (G6). The number-average molecular weight was 11,000.

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[0122] [Synthesis Example 8] (Synthesis of polyethersulfone (PES)-based block copolymer precursor b4', consisting of a segment represented by the following general formula (G8) and a segment represented by the following general formula (G9)) 1.62 g of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide were mixed and adjusted to 70°C. 2.15 g of 2,2'-bipyridyl was added to this mixture and stirred at the same temperature for 10 minutes to prepare a nickel-containing solution.

[0123] Here, 1.49 g of neopentyl 2,5-dichlorobenzenesulfonic acid and 0.50 g of Sumika Excel PES5200P (manufactured by Sumitomo Chemical Co., Ltd., Mn=40,000, Mw=94,000), represented by the following general formula (G7), were dissolved in 5 mL of dimethyl sulfoxide to obtain a solution. 1.23 g of zinc powder was added to this solution, and the temperature was adjusted to 70°C. The nickel-containing solution was poured in, and the polymerization reaction was carried out at 70°C for 4 hours. The reaction mixture was added to 60 mL of methanol, and then 60 mL of 6 mol / L hydrochloric acid was added and stirred for 1 hour. The precipitated solid was separated by filtration and dried to obtain 1.62 g of a block copolymer precursor b3' containing segments represented by the following general formulas (G8) and (G9), with a yield of 99%. The weight-average molecular weight was 230,000.

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[0127] [Polymer electrolyte coating P1] A polymer electrolyte solution consisting of a block copolymer b1 containing oligomer a2 as an ionic segment and oligomer a1 as a nonionic segment. The block copolymer b1 obtained in Synthesis Example 4 was dissolved in NMP and pressure filtered using a 1 μm polypropylene filter to obtain polymer electrolyte coating solution P1 (polymer electrolyte concentration 13% by mass). The viscosity of polymer electrolyte coating solution P1 was 1,300 mPa·s.

[0128] [Polymer electrolyte coating P2] A polymer electrolyte solution consisting of polyarylene-based block copolymer b2 represented by the following general formula (G10). 540 mL of dried N,N-dimethylacetamide (DMAc), 135.0 g (0.336 mol) of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate obtained in Synthesis Example 6, 40.7 g (5.6 mmol) of the nonionic oligomer represented by general formula (G6) obtained in Synthesis Example 7, 6.71 g (16.8 mmol) of 2,5-dichloro-4'-(1-imidazolyl)benzophenone, 6.71 g (10.3 mmol) of bis(triphenylphosphine)nickel dichloride, 35.9 g (0.137 mol) of triphenylphosphine, 1.54 g (10.3 mmol) of sodium iodide, and 53.7 g (0.821 mol) of zinc were mixed under nitrogen.

[0129] The reaction system was heated with stirring (ultimately reaching 79°C) and allowed to react for 3 hours. An increase in viscosity was observed in the system during the reaction. The polymerization reaction solution was diluted with 730 mL of DMAc, stirred for 30 minutes, and then filtered using Celite as a filter aid.

[0130] The filtrate was concentrated using an evaporator, and 43.8 g (0.505 mol) of lithium bromide was added to the filtrate. The reaction was carried out at an internal temperature of 110°C for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature and poured into 4 L of acetone to solidify. The solidified material was filtered, air-dried, pulverized with a mixer, and washed with 1,500 mL of 1N hydrochloric acid while stirring. After filtration, the product was washed with deionized water until the pH of the washing solution was 5 or higher, and then dried overnight at 80°C to obtain 23.0 g of polyarylene-based block copolymer b2. The weight-average molecular weight of this deprotected polyarylene-based block copolymer b2 was 190,000, and the ion exchange capacity (IEC) was 2.0 meq / g. The obtained polyarylene-based block copolymer b2 was dissolved in a mixed organic solvent of N-methyl-2-pyrrolidone / methanol = 30 / 70 (mass%) to a concentration of 0.1 g / g to obtain polymer electrolyte coating solution P2. The viscosity of the polymer electrolyte coating solution P2 was 1,200 mPa·s.

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[0132] [Polymer electrolyte coating P3] A polymer electrolyte solution consisting of polyethersulfone-based block copolymer b3. 0.23 g of the block copolymer precursor b3' obtained in Synthesis Example 8 was weighed and added to a mixed solution of 0.16 g of lithium bromide monohydrate and 8 mL of NMP, and reacted at 120°C for 24 hours. The reaction mixture was poured into 80 mL of 6 mol / L hydrochloric acid and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain block copolymer b3, which consisted of a grayish-white segment represented by the general formula (G9) and a segment represented by the chemical formula (G11) below. The weight-average molecular weight of the obtained polyethersulfone-based block copolymer b3 was 190,000, and the ion exchange capacity (IEC) was 2.0 meq / g. The obtained polyethersulfone-based block copolymer b3 was dissolved in an organic solvent at a concentration of 0.1 g / g to obtain polymer electrolyte coating solution P3 by dissolving it in N-methyl-2-pyrrolidone / methanol = 30 / 70 (mass%). The viscosity of polymer electrolyte coating solution P3 was 1,300 mPa·s.

[0133] [ka]

[0134] [Catalyst coating solution C4] A mixture was prepared by combining TEC10V60TPM (platinum load 60% by mass), a platinum catalyst-supported carbon particle (hereinafter referred to as catalyst particle) manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., with a dispersion of D2020 "Nafion" (registered trademark) (hereinafter referred to as ionomer) manufactured by Chemours K.K. At this time, the mass ratio of ionomer / catalyst particle in the cathode catalyst, B / P, was prepared. c The mixing ratio was adjusted to 0.33, and the mixture was diluted with a water / 1-propanol mixture (mass ratio 1 / 2) so that the total solid content concentration of the ionomer mass and catalyst particle mass was 14 wt%. The resulting diluted solution was stirred using a bead mill and dispersed and crushed until no catalyst particles larger than 10 μmφ remained, in order to prepare a uniform catalyst coating solution C4.

[0135] [Catalyst coating solution C5] Instead of TEC10V60TPM (60% platinum load), use TEC10E60TPM (60% platinum load) platinum-supported high-specific-surface-area carbon particles manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., B / P c Catalyst coating solution C5 was prepared in the same manner as catalyst coating solution C4, except that the ratio was set to 0.33.

[0136] [Catalyst coating liquid C6] Catalyst coating solution C6 was prepared in the same manner as catalyst coating solution C4, except that the catalyst particles with a diameter of 1 μmφ were dispersed and crushed using a bead mill until no more catalyst particles were present.

[0137] [Example 1] [Fabrication of solid polymer electrolyte membranes] A Toray Industries, Inc. PET film "Lumirror" (registered trademark) 125T60 was bonded and fixed to a SUS plate using "Kapton" (registered trademark) tape. After pressure filtering of solid polymer electrolyte membrane coating solution P1 using a 1 μm polypropylene filter, it was cast onto the PET film using a knife coater and dried to obtain a film-like membrane. Furthermore, this membrane was immersed in a 10% by mass sulfuric acid aqueous solution at 80°C for 24 hours to undergo proton substitution and deprotection reactions, and then thoroughly washed by immersion in a large excess of pure water for 24 hours to obtain a solid polymer electrolyte membrane (thickness 10 μm).

[0138] [Fabrication of electrolyte membranes with catalyst layer] The solid polymer electrolyte membrane obtained above was sandwiched between two catalyst layers as shown below, heated and pressed at 150°C and 5 MPa for 3 minutes, cooled to below 40°C under pressure, and then the pressure was released to obtain an electrolyte membrane with a catalyst layer.

[0139] <Catalyst layer transfer sheet> A commercially available polytetrafluoroethylene film contains 0.27 mg / cm² of platinum. 2 A catalyst layer transfer sheet (decal) was prepared by casting catalyst coating solution C4 and drying it at 120°C for 10 minutes.

[0140] [Example 2] In Example 1, only the cathode catalyst layer transfer sheet was coated with catalyst coating solution C5, resulting in a platinum content of 0.61 mg / cm². 2 An electrolyte membrane with a catalyst layer was prepared in the same manner as in Example 1, except that the amount of coating was changed to achieve the desired result.

[0141] [Example 3] An electrolyte membrane with a catalyst layer was prepared in the same manner as in Example 1, except that coating solution P2 for solid polymer electrolyte membranes was used instead of coating solution P1 for solid polymer electrolyte membranes.

[0142] [Example 4] An electrolyte membrane with a catalyst layer was prepared in the same manner as in Example 1, except that coating solution P3 for solid polymer electrolyte membranes was used instead of coating solution P1 for solid polymer electrolyte membranes.

[0143] [Comparative Example 1] In Example 1, only the cathode catalyst layer transfer sheet was coated with catalyst coating solution C6, resulting in a platinum content of 0.26 mg / cm². 2 An electrolyte membrane with a catalyst layer was prepared in the same manner as in Example 1, except that the amount of coating was changed to achieve the desired result.

[0144] [evaluation] For the cathode catalyst transfer sheets prepared in the above examples and comparative examples, the BET specific surface area was measured using the method described in (5) above, and the transition metal catalyst amount was measured using the method described in (6) above. In addition, the fuel cell performance of the electrolyte membrane with catalyst layer was evaluated using the method described in (4) above. The results are shown in Table 1.

[0145] [Table 1] [Explanation of symbols]

[0146] 1 fuel cell 10 Solid polymer electrolyte membrane 21 Cathode catalyst layer 22 Anode catalyst layer 31 Cathode electrode substrate 32 Anode electrode substrate 41, 42 Separators

Claims

1. An electrolyte membrane with a catalyst layer comprising an anode catalyst layer, a cathode catalyst layer, and a solid polymer electrolyte membrane sandwiched between the anode catalyst layer and the cathode catalyst layer, wherein the cathode catalyst layer comprises a transition metal catalyst supported on conductive particles and a polymer electrolyte, and the BET specific surface area of ​​the cathode catalyst layer is 31 m². ２ An electrolyte membrane with a catalyst layer, having a concentration of 1 / g or more.

2. The BET specific surface area of ​​the cathode catalyst layer is 150 m². ２ The electrolyte membrane with a catalyst layer according to claim 1, wherein the amount is less than or equal to / g.

3. The BET specific surface area of ​​the cathode catalyst layer is 50 m². ２ The electrolyte membrane with a catalyst layer according to claim 1, wherein the amount is less than or equal to / g.

4. The electrolyte membrane with a catalyst layer according to claim 1, wherein the conductive particles contained in the cathode catalyst layer include at least one selected from the group consisting of metal particles, metal oxide particles, and carbon particles.

5. The electrolyte membrane with a catalyst layer according to claim 3, wherein the conductive particles contained in the cathode catalyst layer are carbon particles.

6. The electrolyte membrane with a catalyst layer according to claim 1, wherein the transition metal catalyst contained in the cathode catalyst layer includes at least one selected from the group consisting of platinum, gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium, cobalt, manganese, nickel, and two or more alloys thereof.

7. The electrolyte membrane with a catalyst layer according to claim 1, wherein the polymer electrolyte contained in the cathode catalyst layer is a fluorine-based polymer electrolyte.

8. The catalyst layer-equipped electrolyte membrane according to claim 1, wherein the solid polymer electrolyte membrane contains a hydrocarbon-based polymer electrolyte.

9. The catalyst layer-equipped electrolyte membrane according to claim 1, wherein the solid polymer electrolyte membrane contains an aromatic hydrocarbon polymer electrolyte.

10. A fuel cell comprising an electrolyte membrane with a catalyst layer according to any one of claims 1 to 9.

11. A water electrolysis hydrogen generator comprising an electrolyte membrane with a catalyst layer according to any one of claims 1 to 9.

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