Catalyst coated electrolyte membrane

Abstract

Provided is a catalyst coated electrolyte membrane which has a low voltage in an anion exchange membrane-type water electrolysis test, has excellent water electrolysis performance, and has extremely high durability to such an extent that there is no problem even when used in the AEMWE method. A catalyst coated electrolyte membrane (100) has: (A) an electrolyte membrane (11) having a rupture point stress of 85 MPa or more; and (B) catalyst layers (12, 13).

Description

Catalyst coated electrolyte membrane

[0001] The present disclosure relates to a catalyst-coated electrolyte membrane used for water electrolysis, and more specifically to a catalyst-coated electrolyte membrane in which an anion exchange membrane (AEM) is used as the electrolyte membrane and is coated with a catalyst layer.

[0002] Electrolyte membranes are used in various fuel cells, such as polymer electrolyte fuel cells and solid alkaline fuel cells, as well as in various electrolysis technologies, such as water electrolysis. These electrolyte membranes are required to have excellent ionic conductivity and durability sufficient for long-term use.

[0003] Among water electrolysis methods, anion exchange membrane water electrolysis (AEMWE) has been proposed as an alternative technology to cation exchange membrane water electrolysis and alkaline water electrolysis, and has attracted attention in recent years. This method uses an anion exchange membrane (AEM) as a membrane separating the anode chamber and the cathode chamber, and pure water or an alkaline aqueous solution is supplied to the anode chamber as an anolyte. Pure water or an alkaline aqueous solution may be supplied to the cathode chamber as an anolyte, but a dry cathode electrolytic cell in which no anolyte is supplied to the cathode chamber is also possible. In this dry cathode electrolytic cell, water permeates from the anode chamber into the cathode chamber through the anion exchange membrane, thereby supplying water to the cathode chamber. Hydrogen gas and hydroxide ions are generated from the water in the cathode chamber by a cathode reaction.

[0004] The electrolyte membrane used in the AEMWE method is a catalyst-coated membrane (hereinafter referred to as CCM). That is, this CCM has a layered structure and is generally composed essentially of an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer, with an ionomer layer disposed between each catalyst layer and the electrolyte membrane.

[0005] For example, Patent Document 1 discloses the configuration of a water electrolyzer used in the AEMWE process. When water electrolysis is performed with this configuration, excessive pressure is applied from the anode chamber to the cathode chamber, causing a load on the CCM. Therefore, durability is highly required for the CCM. Furthermore, unlike cation exchange membrane water electrolysis and alkaline water electrolysis, the state change from liquid to gas occurs continuously in the catalyst layer or ionomer layer and the electrolyte membrane layer, so the mechanical strength required for the CCM is even greater.

[0006] Patent Document 2 discloses a polymer having a structure in which divalent aromatic groups having ionic functional groups and spirobifluorene skeletons are alternately repeated as an anion-conducting polymer for an electrolyte membrane that has excellent chemical durability and solubility in solvents.

[0007] However, Patent Document 2 only evaluates the membrane for use in fuel cells, which does not require consideration of the problems specific to the AEMWE method, and it is unclear what level of strength is required to resolve the problems specific to the AEMWE method.Furthermore, it does not clarify guidelines for improving mechanical strength, such as what characteristics of the electrolyte membrane or catalyst layer should be improved, or how to improve the adhesion of the contact surfaces of each layer.

[0008] International Publication No. 2022 / 244805 Japanese Patent Application Laid-Open No. 2018-135487

[0009] In view of the above circumstances, an object of the present disclosure is to provide a catalyst coated electrolyte membrane that operates at a low voltage in an anion exchange membrane water electrolysis test, has excellent water electrolysis performance, and is excellent in mechanical strength.

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by focusing on the tensile stress at break of the electrolyte membrane. That is, the present disclosure relates to the following 1) to 9). 1): A catalyst-coated electrolyte membrane having (A) an electrolyte membrane having a tensile stress at break of 85 MPa or more, and (B) a catalyst layer. 2): The catalyst-coated electrolyte membrane according to 1) above, in which the (A) electrolyte membrane contains a polymer having an anion exchange group. 3): The catalyst-coated electrolyte membrane according to 1) or 2) above, which has anion exchange membrane-type water electrolysis performance. 4): The catalyst-coated electrolyte membrane according to any one of 1) to 3) above, in which the (A) electrolyte membrane contains (A-1) a polymer having no ion conductivity. 5): The catalyst-coated electrolyte membrane according to any one of 1) to 4) above, in which the (A) electrolyte membrane has an ion exchange capacity of 0.8 to 1.5 mmol / g. 6): A catalyst coated electrolyte membrane according to any one of 1) to 5) above, wherein the (B) catalyst layer contains an ionomer (B-1), and the breaking stress of the ionomer is 0.01 or more and 0.5 or less relative to the breaking stress of the (A) electrolyte membrane. 7): A catalyst coated electrolyte membrane according to 6) above, wherein the (B-1) ionomer contains the same polymer as that used in the (A) electrolyte membrane. 8): A catalyst coated electrolyte membrane according to any one of 1) to 7) above, wherein the (A) electrolyte membrane has a pore filling structure. 9): A catalyst coated electrolyte membrane according to any one of 1) to 8) above, wherein the (A) electrolyte membrane contains a polymer having a structural unit represented by the following formula (1): However, Ar １ is an aromatic group having an ion exchange group or a group in which aromatic rings having an ion exchange group are linked via a single bond, and there are a plurality of Ar １ may be the same or different, Ar ２ is an aromatic group having no ion-exchange group, or a group in which two or more aromatic rings having no ion-exchange group are linked via a single bond or a spiro atom, and a plurality of Ar ２ may be the same or different, Ar １ and an aromatic ring having Ar ２ is linked to the aromatic ring of the formula (I) via a single bond.

[0011] According to the present disclosure, it is possible to provide a catalyst-coated electrolyte membrane that operates at a low voltage in an anion exchange membrane water electrolysis test, has excellent water electrolysis performance, and is highly durable enough to be used in the AEMWE method without any problems.

[0012] 1 is a diagram showing an example of a layer structure of a catalyst coated electrolyte membrane of the present embodiment, and FIG. 2 is a diagram showing another example of a layer structure of a catalyst coated electrolyte membrane of the present embodiment.

[0013] An example of an embodiment to which the present disclosure is applied will be described below. Numerical values ​​specified in this specification are values ​​determined by the methods disclosed in the embodiments or examples. Note that other embodiments are also included in the scope of the present disclosure as long as they are consistent with the spirit of the present disclosure. Furthermore, in this disclosure, the use of "to" to indicate a range of numerical values ​​means that the numerical values ​​before and after it are included as the lower and upper limits.

[0014] The catalyst-coated electrolyte membrane of the present disclosure includes (A) an electrolyte membrane having a stress at break of 85 MPa or more (hereinafter also referred to as the (A) electrolyte membrane) and (B) a catalyst layer. FIG. 1 shows an example of the layer structure of the catalyst-coated electrolyte membrane of the present embodiment. As shown in the figure, the catalyst-coated electrolyte membrane 100 includes an electrolyte membrane 11, a first catalyst layer 12 formed on a first main surface of the electrolyte membrane 11, and a second catalyst layer 13 formed on a second main surface of the electrolyte membrane 11. In the catalyst-coated electrolyte membrane of the present embodiment, the electrolyte membrane 11 is an (A) electrolyte membrane having a stress at break of 85 MPa or more. In the example of FIG. 1, the first catalyst layer 12 and the second catalyst layer 13 are the (B) catalyst layer of the present disclosure. Note that it is sufficient that either the first catalyst layer 12 or the second catalyst layer 13 is the (B) catalyst layer, and the other may be a catalyst layer that does not fall under the category of the (B) catalyst layer. Alternatively, the catalyst-coated electrolyte membrane may include a catalyst layer formed on only one main surface of the electrolyte membrane 11. That is, the catalyst coated electrolyte membrane of the present disclosure may be formed by forming the catalyst layer (B) on at least one side of the electrolyte membrane (A). The electrolyte membrane (A) and the catalyst layer (B) will be described below.

[0015] [(A) Electrolyte Membrane Having a Breaking Stress of 85 MPa or More] The present disclosure uses an (A) electrolyte membrane having a breaking stress of 85 MPa or more. <(A) Electrolyte Membrane> The (A) electrolyte membrane is a membrane containing a polymer having ion exchange groups, and suitable examples include (i) a membrane composed of a polymer having ion exchange groups, and (ii) a membrane composed by impregnating a porous substrate with a polymer having ion exchange groups. The porous substrate is a membrane having a so-called pore-filling structure, and examples include a substrate film or nonwoven fabric having pores. Here, the pores can be selected, for example, from submicron size, micron size, etc. The pores are not limited to those formed in the thickness direction as long as they are connected in the thickness direction of the substrate film.

[0016] Here, "polymer" includes "copolymer" unless otherwise specified. Furthermore, "ion exchange group" refers to a functional group that is dissociative and capable of ion exchange. Furthermore, anion exchange groups are preferred as "ion exchange groups." Anion exchange groups are substituents having a cation, such as groups in which a heteroatom is cationized. Examples of anion exchange groups include quaternary ammonium salts, imidazolium salts, pyridinium salts, and phosphonium salts.

[0017] (Stress at Break) The electrolyte membrane (A) used in the present disclosure has a stress at break of 85 MPa or more. The stress at break is a value measured according to the measurement method shown below. Measurement method: 1) Preparation of test piece In the case of (i) above, a polymer having ion exchange groups is applied and dried to form a self-supporting membrane. In the case of (ii) above, the pores of the substrate film are filled or impregnated with a polymer having ion exchange groups. A polymer without ion conductivity is preferably used as the substrate film. In the case of (i) above, for example, a polymer having ion exchange groups is dissolved in a solvent to form a solution, and the solution is dropped onto a release film, and the solvent is removed to form a film with a thickness of approximately 10 to 40 μm. The release film is then removed. The obtained film is cut into a size of 3 mm x 50 mm to form a test piece. In the case of (ii) above, a polymer having ion exchange groups is dissolved in a solvent to form a solution, and the solution is dripped onto a substrate film having pores. The solvent is then removed to produce a film in which the pores of the substrate film are filled with the polymer having ion exchange groups. The thickness of the substrate film is preferably 10 to 40 μm. The resulting film is then cut into 3 mm x 50 mm pieces to prepare test pieces. As the substrate film, polyolefin films such as polyethylene, polypropylene, and polytetrafluoroethylene (PTFE), and amide films such as polyimide and polyamide are preferably used, with polyolefin films being more preferred. The pore size is preferably submicron. 2) Measurement of Stress at Break: The prepared test piece is subjected to a uniaxial tensile test at 0.3 m / min using an EZ-SX (Shimadzu Corporation) at 25°C and 40% RH, and the stress at break is calculated from the cross-sectional area of ​​the fracture surface. If the strain of the test piece is large and exceeds the measurement limit, a 1.5 mm x 50 mm test piece may also be used.

[0018] The lower limit of the stress at break is 85 MPa, but in order of preference, 90 MPa, 95 MPa, 100 MPa, 115 MPa, 120 MPa, and 125 MPa are listed, with 130 MPa being particularly preferred. The upper limit is determined in relation to other components and cannot be discussed in general, but may be, for example, about 200 MPa, with 150 MPa being particularly preferred. Therefore, the most preferred stress at break is 125 MPa or more and 150 MPa or less.

[0019] (Polymer) The polymer having an ion exchange group used in the electrolyte membrane (A) of the present disclosure is preferably a polyarylene polymer. By using a polyarylene polymer, an electrolyte membrane with excellent chemical durability can be obtained. Furthermore, the polyarylene polymer is preferably a polymer having a constitutional unit represented by the following general formula (1) (hereinafter also referred to as polymer (P)) in order to impart excellent ionic conductivity to the pore-filling membrane. However, Ar １ is an aromatic group having an ion exchange group or a group in which aromatic rings having an ion exchange group are linked via a single bond, and there are a plurality of Ar １ may be the same or different, Ar ２ is an aromatic group having no ion-exchange group, or a group in which two or more aromatic rings having no ion-exchange group are linked via a single bond or a spiro atom, and a plurality of Ar ２ may be the same or different, Ar １ and an aromatic ring having Ar ２ is linked to the aromatic ring of the formula (I) via a single bond.

[0020] The polymer (P) is a polymer having two or more of the structural unit (1), and is a polymer having an ion-exchange group, Ar １ and Ar having no ion exchange group ２ Ar has a structure in which １ and the aromatic group Ar ２ The aromatic groups contained in the polymer (P) are bonded to each other by single bonds to form the main chain. The polymer (P) has an ether oxygen (—O—), sulfonyl (—S(═O) ２The aromatic rings herein refer to aromatic rings that constitute the main chain, and the aromatic rings that constitute the main chain may further have aromatic rings as substituents. The aromatic rings that constitute the main chain are distinguished from the aromatic rings that are present as substituents (side chains).

[0021] Ar １ is an aromatic group having an ion-exchange group, or a group in which aromatic rings having an ion-exchange group are linked via a single bond.

[0022] When proton conductivity is to be imparted to the polymer (P), the ion exchange group is preferably an acidic group, and the acidic group is, among others, a sulfonic acid group (—SO ３ H group), phosphate group (-H ２ P.O. ４ A sulfonic acid group is more preferred. The H in the acidic group may be dissociated or may be substituted with an alkali metal ion, alkaline earth metal ion, or the like.

[0023] Furthermore, when anion conductivity is imparted to the polymer (P), the ion exchange group is preferably a quaternary ammonium group or an imidazolium group, and more preferably a quaternary ammonium group. From the viewpoint of alkali durability, the quaternary ammonium group is preferably a quaternary alkylammonium group. The quaternary alkylammonium group also includes groups in which alkyl groups bonded to nitrogen atoms are bonded to each other to form a ring structure, and may be, for example, an azaadamantyl group or a quinuclidinium group. Preferred specific examples of the quaternary ammonium group include groups represented by the following formulas (e-1) to (e-8). Preferred specific examples of the imidazolium group include a group represented by the following formula (f-1), and more preferably a group represented by the following formula (f-2) or (f-3).

[0024] In the formula, R ｅ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms; R ｆare each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an aromatic group which may have a substituent, and A － is a monovalent or divalent or more anion, and R ｅ or R ｆ If there are multiple R ｅ or R ｆ may be the same or different. １ The bond bonded to the aromatic ring that constitutes the main chain is shown.

[0025] The above R ｅ Specific examples of the alkyl group in the above R include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. ｆ Specific examples of the alkyl group in R include a methyl group, an ethyl group, a propyl group, and a butyl group. ｆ The aromatic group in the formula (I) may be a phenyl group, and the substituent of the phenyl group may be an alkyl group having 1 to 6 carbon atoms.

[0026] Above A － The anion is preferably an inorganic anion, and a chloride ion (Cl － ), bromide ion (Br － ), iodide ion (I － ), bicarbonate ion (HCO ３ － ), carbonate ions (CO ３ ２－ ), hydroxide ions (OH － ), sulfate ions (SO ４ ２－ ), chlorate ion (ClO ３ － ), nitrate ions (NO ３ － ), cyanide ion (CN － ), sulfite ion (HSO ３ － ), bromate ion (BrO ３ ― ), fluorine ion (F － Among these, hydroxide ions (OH － ), bromide ion (Br－ ), bromate ion (BrO ３ ― ), chloride ions (Cl － ), bicarbonate ion (HCO ３ － ), carbonate ions (CO ３ ２－ ), and particularly preferably hydroxide ion (OH － ), bromide ion (Br － ), chloride ions (Cl － ), bicarbonate ion (HCO ３ － ), carbonate ions (CO ３ ２－ )

[0027] The ion exchange group is Ar １ The ion-exchange group may be directly bonded to the aromatic ring constituting the main chain, or may further have a linking group and be bonded to the aromatic ring constituting the main chain via the linking group. Here, the linking group represents an organic group that connects the acidic group, quaternary ammonium group, or imidazolium group of the ion-exchange group to the aromatic ring constituting the main chain. As the organic group, a linear or branched alkylene group is preferred, and a linear alkylene group is particularly preferred. The number of carbon atoms of the alkylene group can be appropriately adjusted depending on the physical properties required of the polymer (P). For example, by setting the number of carbon atoms of the alkylene group to 20 or less, preferably 16 or less, and more preferably 12 or less, the ion-exchange group capacity of the polymer (P) is increased. On the other hand, by setting the number of carbon atoms of the alkylene group to 2 or more, preferably 4 or more, and more preferably 6 or more, excellent solubility and swelling resistance are achieved, making it easier to fill the porous substrate with the polymer (P). Ar １ The number of ion exchange groups per aromatic ring constituting the main chain may be one or more, and from the viewpoints of ion conductivity and polymer stability, one to two are preferred.

[0028] Ar １The aromatic ring constituting the main chain in the above may be a benzene ring, a condensed ring such as a naphthalene ring or an anthracene ring, or a heterocycle containing an oxygen atom (O), a nitrogen atom (N), or a sulfur atom (S) (e.g., thiophene). Furthermore, these aromatic rings may be linked by a single bond. Examples of structures in which multiple rings are linked by a single bond include biphenyl, terphenyl, and fluorene.

[0029] Ar １ In addition to the ion-exchange group, the aromatic ring constituting the main chain in may further have a substituent other than the ion-exchange group. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms which may have a substituent, a phenyl group which may have a substituent, and a halogeno group. Specific examples of the alkyl group include alkyl groups such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, a pentyl group, a hexyl group, and an octyl group, which may have a phenyl group, a halogeno group, or the like as a substituent. Furthermore, examples of the substituent that the phenyl group may have include an alkyl group having 1 to 6 carbon atoms and a halogeno group. Furthermore, examples of the halogeno group include a fluoro group, a chloro group, a bromo group, and an iodo group.

[0030] From the viewpoint of excellent mechanical strength, chemical durability, and ionic conductivity, the Ar １ Among them, it is preferable that Ar is a group represented by any one of the following formulas (a-1) to (a-10). １ may be the same as or different from each other.

[0031] However, R ａ are each independently a hydrogen atom, an ion exchange group, or a substituent not having an ion exchange group, and a plurality of R ａ may be the same or different, R ａ At least one of the groups is an ion exchange group. ２ indicates the bond bonded to

[0032] Ar ２The aromatic ring constituting the main chain of Ar １ and groups linked via a spiro atom. ２ The aromatic ring in may have a substituent other than the anion exchange group. １ The substituents other than the ion exchange group in Ar are the same as those in Ar. ２ In the above, examples of the group in which two or more aromatic rings are linked via a spiro atom include the group represented by the following formula (c1). In addition, examples of the group in which two or more aromatic rings are linked via a single bond include the groups represented by the following formulas (c2) to (c4). The wavy line indicates that Ar １ From the viewpoint of the polymer filling property into the porous substrate, Ar ２ Preferably, does not have a spiro atom.

[0033] However, R Ｃ are each independently a hydrogen atom, a halogen group, or an organic group.

[0034] The weight-average molecular weight of the polymer (P) can be appropriately adjusted in consideration of chemical durability and ease of filling into pores, and can be, for example, in the range of 10,000 to 1,000,000. From the viewpoint of chemical durability, it is preferably 30,000 or more, and more preferably 100,000 or more. In particular, when the porous substrate is a polyolefin-based porous substrate, the polymer (P) can be easily filled into pores even if its weight-average molecular weight is 100,000 or more. The weight-average molecular weight is a polystyrene-equivalent value measured by GPC (gel permeation chromatography).

[0035] The polymer (P) may consist solely of the structural unit represented by general formula (1) (also referred to as structural unit (1)), or may contain other structural units. Examples of other structural units include Ar in the structural unit (1). １ In addition, other structures that may be generated during synthesis may also be included.

[0036] Among these, the following polymers (P1) to (P4) are preferred as the polymer (P). From the viewpoint of the polymer's ability to fill a porous substrate, polymer (P2), polymer (P3) or polymer (P4) are preferred, with polymer (P2) or polymer (P3) being more preferred. Furthermore, from the viewpoint of the polymer's ability to fill, mechanical strength and chemical durability, polymer (P3) is more preferred. These polymers are described in detail below.

[0037] Polymer (P1) The polymer (P1) has a repeating unit represented by the following general formula (1-1).

[0038] However, R １ ~R １０ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and Ar １ is the same as in the formula (1), and the preferred forms are also the same.

[0039] R １ ~R １０ Examples of the alkyl group having 1 to 4 carbon atoms in R include a methyl group, an ethyl group, a propyl group, and a tert-butyl group. １ and R １０ Preferably, at least one of R is an alkyl group. １ and R １０ is more preferably an alkyl group, and further preferably R １ and R １０ More preferably, R is a tert-butyl group. １ and R １０ By having a bulky substituent on at least one of R, aggregation of the polymer due to π-π stacking or the like is suppressed, and the solubility in a solvent is improved. １ ~R ８ are each independently preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.

[0040] The polymer (P1) is an Ar having an anion exchange group. １and spirobifluorene skeletons are alternately repeated. In the polymer (P1), each element constituting the main chain skeleton belongs to an aromatic ring or is a spiro atom having no hydrogen atoms, and the main chain skeleton does not have an ether bond, so decomposition in the presence of alkali or radicals is suppressed, resulting in excellent chemical durability. Furthermore, the spirobifluorene skeleton has a structure in which two fluorenes are twisted at approximately right angles via the spiro atom, and the fluorene skeletons form the main chain, resulting in the entire main chain having numerous bends. Therefore, the planarity of the main chain is reduced, inhibiting π-π stacking, resulting in excellent solubility in solvents and excellent handleability when filling a porous substrate.

[0041] The method for synthesizing the polymer (P1) is not particularly limited, but a suitable example is the method shown in Scheme A1 below.

[0042] In Scheme A1, R ａ represents an anion exchange group, R ｂ represents R in general formula (1-1). １ and R １０ represents a substituent corresponding to:

[0043] In the example of Scheme A1 above, the desired substituent R ｂ A compound (C) having a brominated spirobifluorene skeleton is synthesized from a compound (B) having the following formula (i) to (vii): Separately, a bromide (D) having a desired aromatic ring (a benzene ring in the example of Scheme A1) is reacted with bis(pinacolato)diborane to obtain a compound (C) having a brominated spirobifluorene skeleton represented by the formula (1-1) １ (Step (viii)) Compound (C) and compound (E) are polymerized, and then a desired anion exchange group is introduced to obtain a polymer represented by general formula (1-1) (Steps (ix) to (xi)). The reaction conditions for each of the above steps may be determined with reference to known reactions.

[0044] Polymer (P2) The polymer (P2) has a repeating unit represented by the following general formula (1-2).

[0045] However, R ａ is a group having an anion exchange group, and Ar ２ is the same as in the general formula (1).

[0046] The polymer (P2) is a polymer having two or more of the structural units (1-2) and is a compound whose main chain is wholly aromatic. Because of this structure, the polymer (P2) has excellent resistance to alkalis, radicals, and the like.

[0047] Ar in polymer (P2) ２ Among these, a phenylene group, a biphenylene group, or a terphenylene group is preferable, and a p-phenylene group (formula (Ar-1) below), a 4,4′-biphenylene group (formula (Ar-2) below), or a 4,4″-terphenylene group (formula (Ar-3) below) is more preferable.

[0048] where R is Ar ２ is a substituent that may be possessed, and r is an integer of 0 to 4, and a plurality of R's and r's may be the same or different.

[0049] Ar ２ When Ar is a p-phenylene group, a 4,4'-biphenylene group, or a 4,4''-terphenylene group, the polymer (P2) tends to have a zigzag main chain structure as shown in the following formula. ２ is a p-phenylene group, the same applies to a 4,4'-biphenylene group or a 4,4''-terphenylene group. As shown in the formula below, the polymer (P2) tends to have a zigzag main chain structure, and furthermore, each R ａ is likely to be located outside the folded back of the backbone. Therefore, intramolecular aggregation due to the folded back of the main chain is suppressed. As a result, the polymer can be used to form an electrolyte membrane with excellent ion conductivity.

[0050]

[0051] Group R having an anion exchange group in polymer (P2) ａ is, among others, the following formula (R ａ-1) is preferred.

[0052] However, R ｂ２ is an anion exchange group, and p2 is an integer of 1 or more and 20 or less. The wavy line indicates a bond to the benzene ring.

[0053] The above formula (R ａ In the group represented by {(R ｂ２ The number of carbon atoms from the aryl group to the quaternary carbon) minus 1 may be appropriately adjusted within the range of 1 to 20. Among these, 1 to 15 is preferred, 1 to 12 is more preferred, and 1 to 6 is even more preferred.

[0054] The method for synthesizing the polymer (P2) is not particularly limited, but a suitable example is the method shown in Scheme A2 below.

[0055] However, X, X １ represents a halogen atom, Ar ２ , and p2 are as described above. １ The halogen atom is preferably Br.

[0056] In the example of Scheme A2, first, compound (H) and the desired Ar ２ Compound (I) having the formula (I) is prepared, and compound (H) and compound (I) are polymerized to obtain a polymer having a structural unit represented by (J). Next, a desired anion exchange group is introduced into polymer (J) to obtain polymer (P2). In Scheme A2 above, a quaternary ammonium group is introduced, but other ionic functional groups can also be introduced in a similar manner. The reaction conditions for each of the above steps may be determined with reference to known reactions.

[0057] Polymer (P3) The polymer (P3) is a repeating unit represented by the general formula (1) in which Ar ２ has a partial structure represented by the following formula (2) at both ends.２ is a divalent group containing an aromatic ring having a fluoro group (-F) at the α-position of the terminal carbon atom. ２ The end of Ar １ The wavy line indicates the carbon atom bonded to Ar. １ The dotted lines indicate that part of the aromatic ring is omitted.

[0058]

[0059] The polymer (P3) is an Ar having an anion exchange group. １ and Ar having a partial structure (2) containing a fluoro group (—F). ２ The main chain has a structure in which Ar is alternately arranged. １ and Ar ２ Each of these has an aromatic group, and is excellent in chemical durability against alkalis, radicals, etc. The polymer (P3) has an Ar group having an ion exchange group linked to the side chain end via an alkyl chain. １ and Ar having no ion exchange group ２ are arranged alternately. Because of this structure, the compound has excellent solubility in solvents and ionic conductivity. In addition, the compound having the partial structure (2) is highly reactive with the compound represented by formula (4) described below, making it possible to produce a polymer with a higher molecular weight. By using this high-molecular-weight polymer, it is also possible to form a film with better durability.

[0060] Ar ２ For example, as in formula (b-1) described later, one ring structure (e.g., a benzene ring) may have two partial structures (2), or as in formula (b-2) described later, one C—F bond may constitute two partial structures (2). Furthermore, in the case of the chain polycyclic hydrocarbon, each of the two ring structures of the chain polycyclic hydrocarbon may have one partial structure (2), and these rings may be linked directly or via the linking group, or one of the multiple ring structures may have two partial structures (2). ２ Preferably, does not have a spiro atom.

[0061] The polymer (P3) is preferably selected from the group consisting of Ar and Ar-based polymers, because it is possible to form an electrolyte membrane having excellent ionic conductivity, membrane formability, chemical durability, and membrane strength. ２ is preferably one or more selected from the following formulas (d1) to (d9). １ This shows the bond between .

[0062] However, R ｄ are each independently a hydrogen atom, a halogen group, or an organic group.

[0063] The above R ｄ Examples of the halogeno group in R include a fluoro group, a chloro group, a bromo group, and an iodo group, and among these, a fluoro group is preferred. ｄ The organic group in the formula (I) may be, for example, a linear or branched alkyl group having 1 to 20 carbon atoms (not including the carbon number of the substituent) which may have a substituent (for example, a halogeno group).

[0064] From the viewpoint of ease of production, the above Ar ２ The following formulas (d10) to (d14) are preferred. １ This shows the bond between .

[0065]

[0066] The method for synthesizing the polymer (P3) is not particularly limited, but a suitable example is the method shown in Scheme A3 below.

[0067] However, X １ are each independently Br or I, and Ar ３ is an aromatic group having a functional group selected from a halogeno group, a sulfonate group, a phosphate group, a carboxylate group, an imidazole group, and an amino group, and Ar ２ is the same as in polymer (P3).

[0068] X in compound (4) １ and Ar of compound (5). ２Since the hydrogen atoms of the following partial structure (5a) have excellent reactivity, it is possible to relatively easily synthesize an ion-conducting polymer having a high molecular weight (for example, a weight-average molecular weight of 30,000 or more, preferably 100,000 or more).

[0069]

[0070] In the above scheme A3, first, the desired Ar ３ and a compound (4) having the desired Ar ２ Then, these compounds are reacted with a Pd complex, a ligand, a carboxylic acid (RCO ２ A polymer having the structural unit (3) is obtained by reacting the compound (II) in the presence of methyl group (H) and a base at 80 to 140° C. for 1 to 48 hours.

[0071] Next, the desired ion-exchange group is introduced into the polymer having the structural unit (3), thereby obtaining the polymer (P3). In this manner, the polymer (P3) can be easily produced with an extremely small number of synthesis steps by using the compounds (4) and (5) as raw materials.

[0072] Polymer (P4) The polymer (P4) has a repeating unit represented by the following general formula (1-4).

[0073] However, the ring Ar １１ and ring Ar １２ is a ring fused to a benzene ring, and is a fused ring of three or more rings having aromatic properties as a whole, and Ar １ is the same as in the general formula (1).

[0074] The polymer (P4) is an Ar having an anion exchange group. １ and Ar consisting of three or more fused rings. ２ In general, polymers containing many ion exchange groups tend to swell easily. １ and Ar ２ and are alternately repeated, and condensed rings of three or more rings are π-π stacked, thereby providing excellent swelling resistance.

[0075] Ring Ar１１ and ring Ar １２ is an aromatic ring which may have a heteroatom. Examples of the heteroatom include N (nitrogen atom), O (oxygen atom), and S (sulfur atom). １１ and ring Ar １２ From the viewpoint of swelling resistance, the fused ring containing Ar is preferably a fused ring of 3 or more rings. On the other hand, from the viewpoint of increasing the ion exchange capacity of the polymer (P4), a fused ring of 5 or less rings is preferred, and a fused ring of 4 or less rings is more preferred. Preferred specific examples of the fused ring include the following. The wavy line indicates that Ar １ The hydrogen atom may be substituted with a group that does not have an anion exchange group.

[0076]

[0077] The polymer (P4) is preferably synthesized by preparing a precursor (1-5) having a repeating unit represented by the following general formula (1-5), filling the porous substrate with the precursor, and then eliminating the substituent (TL).

[0078] where LT is a group represented by general formula (LT1) to (LT3), and R １１ are each independently an alkyl group having 1 to 6 carbon atoms, and R １２ is an alkyl group having 1 to 6 carbon atoms or a phenyl group, and Ar １ , Ar １１ , Ar １２ is the same as in the general formula (1-4). １１ and R １２ The alkyl group having 1 to 6 carbon atoms in the formula (I) may be either a linear or branched alkyl group. Specific examples include a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, a pentyl group, and a hexyl group.

[0079] As mentioned above, polymer (P4) has excellent swelling resistance. Therefore, it is difficult to dissolve in various organic solvents, which causes problems with poor handling during processing. The precursor has a bulky substituent (TL) represented by the general formulas (LT1) to (LT3) introduced at a site corresponding to the fused ring of polymer (P4), which is relatively easy to remove by the action of heat or light. The substituent inhibits π-π stacking of the hydrophobic portion of precursor (1-5), improving its solubility in various organic solvents. Therefore, the precursor has excellent handleability and can be easily filled into a porous substrate. The substituent (TL) can be removed by heating or light irradiation.

[0080] The method for synthesizing the precursor is not particularly limited, but a preferred specific example is the method shown in Scheme A4 below.

[0081]

[0082] An example of each step of the above scheme A4 will be described. Step (i): A toluene solution of the above compound (1) is prepared, and diethyl azodicarboxylate (DEAD) is added and heated to reflux to obtain the above compound (2). Step (ii): Separately, an N,N-dimethylformamide (DMF) solution of the above compound (3) is prepared, and bis(pinacolato)diborane, potassium acetate (KOAc), and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (Pd(dppf)Cl ２ Step (iii): To the toluene solution of the obtained compound (2) and the compound (4), tripotassium phosphate (K ３ P.O. ４ ) and tetrakis(triphenylphosphine)palladium (Pd(PPH ３ ) ４) and heated to 100°C to polymerize, thereby obtaining the compound (5). Step (iv): The obtained compound (5), N-bromosuccinimide (NBS), and azobisisobutyronitrile (AIBN) are added to chlorobenzene, mixed, and heated to 110°C to obtain the compound (6). Step (v): The obtained compound (6) is heated to 50°C in a DMF / THF (tetrahydrofuran) mixed solvent to obtain the precursor represented by the chemical formula (7).

[0083] <Pore-filling membrane> The electrolyte membrane used in the present disclosure preferably uses a porous substrate as a substrate film and a pore-filling membrane filled with the above-mentioned polymer. This configuration can impart mechanical strength to a polyarylene polymer with excellent chemical durability. The porous substrate is a substrate having pores capable of retaining a polymer. In order to improve ionic conductivity, it is preferable that at least some of the pores of the porous substrate form through-holes. In order to impart mechanical strength, the substrate is preferably in the form of a nonwoven fabric or a porous film, and more preferably in the form of a porous film. The porosity (= void volume / bulk volume × 100 (%)) of the porous substrate is preferably 30 to 95%, more preferably 40 to 80%, and even more preferably 45 to 70%, in order to achieve both mechanical strength and ionic conductivity. The film thickness of the porous substrate is preferably 5 to 200 μm, more preferably 7 to 100 μm, and even more preferably 10 to 50 μm, in order to achieve both mechanical strength and ionic conductivity. Furthermore, the pore diameter of the porous substrate is preferably 10 to 10,000 nm, more preferably 10 to 1,000 nm, in terms of the average diameter, from the viewpoint of filling and retaining the polyarylene polymer and mechanical strength. The material of the porous substrate is preferably a polyolefin-based porous substrate in terms of chemical durability, particularly stability in alkali. The use of a polyolefin-based porous substrate also has the advantage of being easily filled with polyarylene polymers, particularly high-molecular-weight polyarylene polymers having a weight-average molecular weight of 100,000 or more. Among the polyolefin-based porous substrates, polyethylene porous substrates, polypropylene porous substrates, and polytetrafluoroethylene porous substrates are preferred in terms of mechanical strength and chemical resistance. Among the polyethylene porous substrates, ultra-high molecular weight polyethylene (e.g., weight-average molecular weight of 1,000,000 or more) porous substrates are preferred.

[0084] An example of a method for producing a pore-filling membrane is a method in which a polymer having an ion exchange group, such as a polyarylene polymer, is applied to a porous substrate, the pores of the porous substrate are filled, and the porous substrate is dried. Methods for applying a polyarylene polymer to a porous substrate include, for example, preparing a solution of the polyarylene polymer and using methods such as dipping, spraying, spin coating, and bar coding. The polyarylene polymer solution is permeated into the porous substrate, and then dried to obtain an (A) electrolyte membrane consisting of a pore-filling membrane. The thickness of the (A) electrolyte membrane can be made the same as that of the porous substrate, for example, by producing a pore-filling membrane using a polymer solution in an amount that fills the porosity volume of the porous substrate. Incidentally, the filling of the porous substrate with the polyarylene polymer can be confirmed, for example, by Raman analysis.

[0085] [(B) Catalyst Layer] The catalyst-coated electrolyte membrane of the present disclosure has a structure in which at least one of the main surfaces of the (A) electrolyte membrane is coated with the (B) catalyst layer. The electrolyte membrane used for water electrolysis has an anode catalyst disposed on one surface as an anode and a cathode catalyst disposed on the other surface as a cathode. The anode catalyst is preferably a metal or a metal alloy. The metal or metal alloy can be appropriately selected from known metals and metal alloys, and examples thereof include platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, metal compounds thereof, metal oxides, and alloys containing two or more of these metals. The cathode catalyst is preferably a metal or a metal alloy. The metal or metal alloy can be appropriately selected from known metals and includes, for example, platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, metal compounds thereof, metal oxides, and alloys containing two or more of these metals.

[0086] <(B-1) Ionomer> The catalyst layer (B) of the present disclosure is preferably configured such that the above metal is dispersed in an ionomer (B-1) from the viewpoint of enhancing adhesion to the electrolyte membrane (A) and increasing the reaction specific surface area. The ionomer (B-1) may be a sulfonated fluoropolymer, such as a perfluorinated sulfonic acid (PFSA) ionomer or a partially fluorinated polymer, and Nafion may be used. ＴＭ (Chemours Company), Aquivion® (Solvay Specialty Polymers), Flemion ＴＭ (Asahi Glass Group) and Aciplex ＴＭ PFSA selected from Asahi Kasei Chemicals Corporation is commercially available.

[0087] In the catalyst-coated electrolyte membrane of the present disclosure, the breaking stress of the (B-1) ionomer is preferably 0.01 to 0.5 relative to the breaking stress of the (A) electrolyte membrane. That is, for example, if the breaking stress of the (A) electrolyte membrane is 85 MPa, the breaking stress is preferably 0.85 MPa to 42.5 MPa. This configuration makes it possible to achieve mechanical strength that can withstand use, particularly in the AEMWE method, in which a liquid-to-gas state change occurs continuously. A more preferred lower limit for the breaking stress of the (B) catalyst layer relative to the breaking stress of the (A) electrolyte membrane is 0.05, even more preferably 0.10, and particularly preferably 0.12. The upper limit is preferably 0.35, even more preferably 0.24, and particularly preferably 0.20. Therefore, the most preferred value for the breaking stress of the (B) catalyst layer relative to the breaking stress of the (A) electrolyte membrane is 0.12 to 0.20.

[0088] Here, the breaking stress of the (B-1) ionomer is a value obtained by the same measurement method as that for the (A) electrolyte membrane. That is, it is not measured under actual use conditions, but rather a test piece similar to the (A) electrolyte membrane is prepared, and a uniaxial tensile test is performed at 0.3 m / min using an EZ-SX (manufactured by Shimadzu Corporation) in an environment of 25°C and 40% RH, and the breaking stress is calculated from the cross-sectional area of ​​the fractured surface.

[0089] A preferred method for achieving the above-mentioned stress at break is to use, as the ionomer (B-1), a polymer that is the same as or similar to the polymer having an ion exchange group used in the electrolyte membrane (A). That is, the ionomer (B-1) is preferably selected from polymers having a structural unit represented by the above formula (1). Furthermore, it is particularly preferred to use the same polymer as the polymer having an ion exchange group used in the electrolyte membrane (A).

[0090] In the configuration of the (B) catalyst layer according to the present disclosure, the amount of the (B-1) ionomer in the catalyst layer (i.e., the (B-1) ionomer / catalyst ratio) is preferably 0.05 or more and 1.5 or less. More preferred upper limits are 1.2, 1.0, 0.7, and 0.5, respectively. More preferred lower limits are 0.1, 0.15, and 0.2. Therefore, the most preferred amount of the (B-1) ionomer in the (B) catalyst layer is 0.2 or more and 0.5 or less.

[0091] [Preparation of Catalyst-Coated Electrolyte Membrane] The catalyst-coated electrolyte membrane of the present disclosure can be obtained by forming a (B) catalyst layer on at least one side, more preferably both sides, of an (A) electrolyte membrane. Examples of methods for forming the (B) catalyst layer include pulse spray coating, ultrasonic spray coating, die coater coating, bar coater coating, and electrode transfer coating. Note that, depending on the coating method, a drying step may be included.

[0092] A suitable example of the catalyst-coated electrolyte membrane of the present disclosure is a catalyst-coated electrolyte membrane having anion exchange water electrolysis performance. Fig. 2 shows a schematic cross-sectional view illustrating an example of a catalyst-coated electrolyte membrane having anion exchange water electrolysis performance. The catalyst-coated electrolyte membrane 101 of Fig. 2 has an electrolyte membrane (A) 11 in which a polymer (electrolyte polymer) 1 having ion exchange groups is impregnated into the pores of a substrate film 2, which is a porous substrate. A first catalyst layer 12 having a (B-1) ionomer 3 and a hydrogen generating catalyst 4 is formed on a first main surface of the electrolyte membrane 11, and a second catalyst layer 13 having a (B-1) ionomer 3 and an oxygen generating catalyst 5 is formed on a second main surface of the electrolyte membrane 11.

[0093] The anion exchange membrane water electrolysis performance refers to the performance of an electrochemical cell in which a catalyst layer in which a metal powder having hydrogen generating ability is dispersed in an ionomer is formed on the cathode side of an electrolyte membrane having anion exchange groups, and a catalyst layer in which a metal powder having oxygen generating ability is dispersed in an ionomer is formed on the other anode side, and when an alkaline solution is passed through the electrochemical cell containing the electrolyte membrane ion-exchanged to OH ions by the alkaline solution and the ionomer, water electrolysis is possible without a large increase in voltage when a current is passed from a power source through the electrochemical cell. Specifically, carbon supporting platinum or carbon supporting a platinum-ruthenium alloy is generally used as the hydrogen generating catalyst, while iridium oxide is generally used as the oxygen generating catalyst. When 1 mol / L potassium hydroxide is used as the alkaline solution and the electrochemical cell is at 80°C, the electrolysis performance is 1 A / cm. ２ The voltage should be 2.0 V or less when the voltage is 1.7 V to 1.8 V, and particularly preferably 1.78 V or less. The ion exchange capacity represents the amount of ions that can be adsorbed by an ion exchange resin, and the higher this value, the higher the ionic conductivity. In the electrolyte membrane (A) of the present disclosure, the ion exchange resin is a polymer having ion exchange groups. The higher the ion exchange capacity, the higher the ionic conductivity, but the higher the water content, which causes the electrolyte membrane to swell and the gas barrier properties to deteriorate. For this reason, the ion exchange capacity is preferably 1.0 mmol / g to 2.0 mmol / g, particularly preferably 1.2 mmol / g to 1.9 mmol / g, and most preferably 1.3 to 1.7 mmol / g.

[0094] The catalyst coated electrolyte membrane of the present disclosure is suitable for use in fuel cells and electrolysis devices.

[0095] The present disclosure will be described in more detail below with reference to examples. Note that the present disclosure is not limited to these examples and can be modified as appropriate without departing from the spirit of the present disclosure.

[0096] [Synthesis of Compound (1-1)] In a four-neck flask, n-tetrabutylammonium chloride (3.04 g), 1,10-dichlorodecane (1097 mmol), and 2,7-dibromofluorene (109.7 mmol) were added to a four-neck flask with a syringe and stirred under nitrogen. The mixture was then allowed to react at 90°C under nitrogen for 90 minutes, after which the resulting reaction mixture was cooled to room temperature (25°C). The organic phase in the cooled reaction mixture was extracted with toluene (200 mL) in a separatory funnel and washed with 1 M hydrochloric acid (50 mL) and saturated brine (200 mL × 2). The toluene in the resulting organic phase was removed using an evaporator, and unreacted 1,10-dichlorodecane was removed under reduced pressure at 180°C. The resulting residue was applied to a silica gel column (developing solvent: hexane) to obtain the following compound (1-1) (68.7 mmol).

[0097] [Chemical formula 1-1]

[0098] [Synthesis of Compound (1-2)] Compound (1-1) (57.7 mmol) and 1,3,5-trimethylbenzene (159 mL) were added to a separable flask and stirred while bubbling with nitrogen (20 mL / min) for 30 min. Next, cesium carbonate (173 mmol), pivalic acid (57.7 mmol), tris(2-methoxyphenyl)phosphine (407 mg), and Pd ２ (dba) ３(291 mg) and 1,2,4,5-tetrafluorobenzene (57.7 mmol) were added and stirred. This mixture was reacted under nitrogen at room temperature (25°C) for 15 minutes, then at 98°C for 8 hours, and then at 75°C for 75 minutes. 1M hydrochloric acid (100 mL) and toluene (600 mL) were added to the resulting reaction product (solids), and the mixture was stirred at 60°C for 30 minutes. After that, insoluble matter was removed by vacuum filtration, and the organic phase was extracted using a separatory funnel. The extracted organic phase was washed with 1M hydrochloric acid and saturated saline, and the liquid in the resulting organic phase was removed using an evaporator and dried. The resulting residue was dissolved in toluene and reprecipitated in hexane / methanol = 3 / 1. The resulting precipitate was filtered to remove the liquid. The resulting solids were dried in vacuo to obtain compound (1-2) with a molecular weight distribution of 4.88. The GPC results shown in FIG. 2 indicate that the compound (1-2) had a peak end at 14.025 min, indicating that the amount of low molecular weight compounds was reduced.

[0099] [Chemical formula 1-2]

[0100] [Synthesis of Compound (1-3)] Compound (1-2) (2.07 g) was dissolved in 3-methoxy-N,N-dimethylpropanamide (25 mL). To the resulting solution, 25% by mass trimethylamine methanol solution (10 mL) was added, and the mixture was stirred at 100°C for 9 hours. After that, the mixture was cooled to room temperature (25°C), and the solution was reprecipitated in toluene. The resulting precipitate was filtered to remove the liquid. The resulting solid was dried in vacuum to obtain compound (1-3) (2.29 g). As described above, compound (1-2) was synthesized so as to minimize the content of low molecular weight compounds, and therefore, compound (1-3) is presumed to similarly contain few low molecular weight compounds.

[0101] [Chemical formula 1-3]

[0102] [Electrolyte Membrane 1] A porous substrate was prepared by heating polyethylene (Hipore NH815, manufactured by Asahi Kasei Corporation) having submicron-sized pores. A solution of the compound represented by Chemical Formula 1-3 in a solvent was added dropwise to the heated porous substrate. The solvent was dried at 80°C to fill the pores with the compound, thereby obtaining an electrolyte membrane 1 having a thickness of 13 μm.

[0103] <Measurement of Breaking Stress of Electrolyte Membrane> The electrolyte membrane 1 was cut into a size of 1.5 mm x 50 mm, and a uniaxial tensile test was performed at 0.3 m / min using an EZ-SX (manufactured by Shimadzu Corporation) in an environment of 25°C and 40% RH, and the breaking stress was calculated from the cross-sectional area of ​​the fractured surface. The results are shown in Table 1.

[0104] [Electrolyte Membranes 2 to 4] The breaking stress of each of Fumasep FAAM-20 (manufactured by Fumatech), CMX-40-10 (manufactured by ORION Polymers), and PiperION-A20-HCO3 (manufactured by Versogen) electrolyte membranes 2 to 4 was measured in the same manner as above. The results are shown in Table 1.

[0105] [(B-1) Measurement of Ionomer Breaking Stress] A glass plate was heated, and a solution of the compound represented by Chemical Formula 1-3 dissolved in a solvent (a mixed solution of dimethyl sulfoxide and hexanol) was dropped onto the heated glass plate. The solvent was dried at 80°C, and the film composed of the ionomer was peeled off from the glass to prepare a 28 μm test piece. The obtained ionomer film was cut into 3.0 mm x 50 mm pieces and subjected to a uniaxial tensile test at 0.3 m / min using an EZ-SX (manufactured by Shimadzu Corporation) in an environment of 25°C and 40% RH. The breaking stress was calculated from the cross-sectional area of ​​the fractured surface. The results are shown in Table 2.

[0106]

[0107] <Ion Exchange Capacity Test> 50 mg of electrolyte membranes 1 to 4 were immersed in a 1 mol / L aqueous sodium nitrate solution and left at 25°C for 24 hours. Once the chloride ions and nitrate ions in the electrolyte membranes were fully ion-exchanged, potentiometric titration was performed with a 0.02 mol / L aqueous silver nitrate solution. The ion exchange capacity was calculated from the titration amount up to the inflection point and the weight of the electrolyte membrane. For electrolyte membranes 2 to 4, the membranes were immersed in a sodium chloride aqueous solution for 48 hours for the purpose of anion exchange, and then potentiometric titration was performed using the method described above. The titration was performed using a HIRANUMA COM-A19. For electrolyte membrane 1, porous substrates with different thicknesses of 15 μm, 9 μm, and 25 μm were prepared, and a solution containing a polymer component was applied in an amount 1.1 times the pore volume calculated from the porosity and thickness of each porous substrate. Electrolyte membranes 1 with different thicknesses were then fabricated and subjected to the same test. The calculation method is shown in Calculation Method 1, and the results are shown in Table 3. [Calculation method 1] Exchange capacity (mmol / g) = (EP1 - BL1) x TF x C1 x K1 / S EP1: Titration volume required to reach the first endpoint (mL) BL1: Titration volume required for the blank test (mL) TF: Factor of the titrant (1.0003) C1: Concentration conversion coefficient (0.0001 mol / mL) K1: Unit conversion coefficient (1000) S: Sample volume (g)

[0108]

[0109] Example 1 Catalyst-Coated Electrolyte Membrane 1 A compound represented by Chemical Formula 1-3 was dissolved in a solvent (a mixture of isopropanol and water), and platinum-ruthenium-supported carbon (TEC66E50, manufactured by Tanaka Kikinzoku) was dispersed in the solution to obtain a metal-dispersed ionomer solution 1. Irridium oxide (Premion, manufactured by THERMO SCIENTIFIC CHEMICALS) was used instead of the platinum-ruthenium-supported carbon to obtain an ionomer solution 2 in the same manner. The ionomer solution 1 was applied to the electrolyte membrane 1 by spray coating, and the membrane was dried at 80°C. The opposite surface of the membrane was then coated with the ionomer solution 2 by spray coating, and the membrane was dried at 80°C to obtain a catalyst-coated electrolyte membrane 1 (catalyst area 1 cm × 1 cm) according to the present disclosure. The thickness of the catalyst to be coated was determined by spraying metal-dispersed ionomer solution 1, in which the ionomer / carbon ratio was adjusted to 0.5, and the platinum content in the coated catalyst was 0.5 mg / cm. ２ Metal-dispersed ionomer solution 2, in which the ionomer / iridium ratio had been adjusted to 0.29 in the same manner as above, was spray-coated, and the thickness was adjusted while being quantified by fluorescent X-ray analysis so that the iridium loading in the coated catalyst was 1.5 mg / cm.

[0110] Comparative Example 1: Catalyst-coated electrolyte membrane 2 Comparative Example 1 (catalyst-coated electrolyte membrane 2) was obtained in the same manner as in Example 1, except that the electrolyte membrane 1 was replaced with the electrolyte membrane 2.

[0111] <Anion exchange membrane water electrolysis test> A nickel porous body was installed on the anode side of the catalyst coated electrolyte membrane of Example 1 and Comparative Example 1, and carbon paper was installed on the cathode side as a porous transport layer PTL. An anion exchange membrane water electrolysis test was carried out using a JARI standard cell at 80°C with a liquid flow rate of 1 cc / min on the anode side and 0 cc / min on the cathode side. 1 A / cm ２ The measurement results are shown in Table 4. This voltage value was calculated from the average value of 60 data points from 2 minutes 1 second to 3 minutes 0 seconds, measured every second for 3 minutes.

[0112] <Alkaline durability test> An impregnation test in a 1 M potassium hydroxide aqueous solution, the same as in the anion exchange membrane water electrolysis test, was carried out for 400 hours, and the cell resistance was measured at 1.5 V. The rate of change from the initial value was calculated. The results are shown in Table 5.

[0113] The test results of Example 1 confirmed that the catalyst coated electrolyte membrane of the present disclosure exhibited low voltage in the anion exchange membrane water electrolysis test and excellent water electrolysis performance. Furthermore, the rate of change in cell resistance in alkaline durability was small, confirming excellent alkaline durability.

[0114] According to the present disclosure, it is possible to provide a catalyst coated electrolyte membrane that is extremely durable and can be used in the AEMWE method without any problems.

[0115] This application claims priority based on Japanese Patent Application No. 2023-194981, filed November 16, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0116] 1: Polymer having ion exchange groups (electrolyte polymer), 2: Substrate film, 3: Ionomer, 4: Hydrogen generation catalyst, 5: Oxygen generation catalyst, 11: Electrolyte membrane, 12: First catalyst layer, 13: Second catalyst layer, 100: Catalyst-coated electrolyte membrane

Claims

1. (A) an electrolyte membrane having a breaking stress of 85 MPa or more, and (B) a catalyst-coated electrolyte membrane having a catalyst layer.

2. The catalyst coated electrolyte membrane according to claim 1, wherein the electrolyte membrane (A) contains a polymer having an anion exchange group.

3. The catalyst-coated electrolyte membrane according to claim 1 or 2, which has anion-exchange membrane-type water electrolysis performance.

4. The catalyst coated electrolyte membrane according to claim 1 or 2, wherein the electrolyte membrane (A) contains a polymer (A-1) that does not have ion conductivity.

5. The catalyst-coated electrolyte membrane according to claim 1 or 2, wherein the ion exchange capacity of the electrolyte membrane (A) is 0.8 to 1.5 mmol / g.

6. A catalyst-coated electrolyte membrane according to claim 1 or 2, wherein the (B) catalyst layer contains an (B-1) ionomer, and the breaking stress of the ionomer is 0.01 or more and 0.5 or less relative to the breaking stress of the (A) electrolyte membrane.

7. The catalyst coated electrolyte membrane according to claim 6, wherein the ionomer (B-1) is the same polymer as that used in the electrolyte membrane (A).

8. The catalyst-coated electrolyte membrane according to claim 1 or 2, wherein the electrolyte membrane (A) has a pore-filling structure.

9. The catalyst-coated electrolyte membrane according to claim 1 or 2, wherein the electrolyte membrane (A) contains a polymer having a structural unit represented by the following formula (1): However, Ar １ is an aromatic group having an ion exchange group, or a group in which aromatic rings having an ion exchange group are linked via a single bond, １ may be the same or different, Ar ２ is an aromatic group having no ion exchange group, or a group in which two or more aromatic rings having no ion exchange group are linked via a single bond or a spiro atom, ２ may be the same or different, Ar １ and an aromatic ring represented by Ar ２ is bonded to the aromatic ring contained in the ring via a single bond.

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