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

[Technical Field]

[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. [Background technology]

[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) to separate the anode and cathode chambers, and pure water or an alkaline aqueous solution is supplied to the anode chamber as the anolyte. Pure water or an alkaline aqueous solution may be supplied to the cathode chamber as the anolyte, but it is also possible to use a dry cathode electrolytic cell in which no anolyte is supplied to the cathode chamber. In this dry cathode electrolytic cell, water permeates from the anode chamber to the cathode chamber through the anion exchange membrane, supplying water to the cathode chamber. Hydrogen gas and hydroxide ions are generated from the water in the cathode chamber through a cathode reaction.

[0004] The electrolyte membrane used in this AEMWE method is a catalyst-coated membrane (CCM), which is generally constructed in a layered structure essentially consisting 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 CCM is required to have a higher mechanical strength because the state changes from liquid to gas continuously between the catalyst layer or ionomer layer and the electrolyte membrane layer.

[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 electrolyte membranes that has excellent chemical durability and solubility in solvents.

[0007] However, Patent Document 2 only evaluates fuel cell applications, which do not require consideration of the issues specific to the AEMWE method, and it is unclear what level of strength is required to resolve the issues specific to the AEMWE method.Furthermore, guidelines for improving mechanical strength, such as what properties of the electrolyte membrane or catalyst layer should be improved, or how to improve the adhesion of the contact surfaces of each layer, are not clear. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2022 / 244805 [Patent Document 2] Japanese Patent Application Publication No. 2018-135487 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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) 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 1) above, wherein the electrolyte membrane (A) 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, wherein the electrolyte membrane (A) contains (A-1) a polymer that does not have ion conductivity. 5): The catalyst-coated electrolyte membrane according to any one of 1) to 4) above, wherein the ion exchange capacity of the electrolyte membrane (A) is 0.8 to 1.5 mmol / g. 6): The catalyst-coated electrolyte membrane according to any one of 1) to 5) above, 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 6) above, 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 any one of 1) to 7) above, wherein the electrolyte membrane (A) has a pore filling structure. 9): The catalyst-coated electrolyte membrane according to any one of 1) to 8) above, wherein the electrolyte membrane (A) contains a polymer having a structural unit represented by the following formula (1): [ka] 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 of Ar 2 is linked to the aromatic ring of the formula (I) via a single bond. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an example of a layer structure of a catalyst coated electrolyte membrane according to an embodiment of the present invention. [Figure 2] FIG. 3 is a diagram showing another example of the layer structure of the catalyst coated electrolyte membrane of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An example of an embodiment to which the present disclosure is applied will be described below. The numerical values ​​specified in this specification are values ​​determined by the methods disclosed in the embodiments or examples. Other embodiments are also included within the scope of the present disclosure as long as they are consistent with the spirit of the present disclosure. Furthermore, in this disclosure, the symbol "to" indicating a numerical range 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 has (A) an electrolyte membrane having a breaking stress of 85 MPa or more (hereinafter also referred to as (A) electrolyte membrane), and (B) a catalyst layer. FIG. 1 shows an example of the layer structure of a catalyst-coated electrolyte membrane of this 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 this embodiment, the electrolyte membrane 11 is an electrolyte membrane having a (A) breaking stress 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. The catalyst-coated electrolyte membrane may also have 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 have a (B) catalyst layer formed on at least one of the (A) electrolyte membranes. (A) The electrolyte membrane and (B) the catalyst layer will be described below.

[0015] [(A) Electrolyte membrane with a breaking stress of 85 MPa or more] The present disclosure uses (A) an 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 thereof include a substrate film or nonwoven fabric having pores. Here, the pores can be selected, for example, from submicron size to micron size. The pores need only be connected in the thickness direction of the substrate film, and are not limited to those formed in the thickness direction.

[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 breaking stress of 85 MPa or more. The stress at break is a value measured according to the following measurement method. Measurement methods; 1) Preparation of test specimens In the case of (i) above, a polymer having ion exchange groups is applied and dried to form a self-supporting film. 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 produce a film with a thickness of about 10 to 40 μm.The release film is then removed, and the obtained film is cut into a 3 mm × 50 mm piece to prepare 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 dropped 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 obtained film is then cut into 3 mm × 50 mm pieces to prepare test pieces. The substrate film is preferably a polyolefin film such as polyethylene, polypropylene, or polytetrafluoroethylene (PTFE), or an amide film such as polyimide or polyamide, with polyolefin film being more preferred. The pore size is preferably submicron. 2) Breaking stress measurement The prepared test piece is subjected to a uniaxial tensile test at 0.3 m / min in an environment of 25°C and 40% RH using an EZ-SX (manufactured by Shimadzu Corporation), and the stress at break is calculated from the cross-sectional area of ​​the fracture surface. If the distortion of the test piece is large and exceeds the measurement limit, a test piece of 1.5 mm x 50 mm may be used.

[0018] The lower limit of the stress at break is 85 MPa, with 90 MPa, 95 MPa, 100 MPa, 115 MPa, 120 MPa, and 125 MPa being more preferred, with 130 MPa being particularly preferred. The upper limit is determined by the relationship with other components and cannot be discussed in detail, but it may be, for example, around 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, because the use of a polyarylene polymer allows for the production of an electrolyte membrane with excellent chemical durability. 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. [ka] 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 of Ar2 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 above-mentioned structural units (1), and 1 and Ar without ion exchange groups 2 It has a structure in which Ar 1 The aromatic group and Ar 2 The aromatic groups contained in are bonded by single bonds to form the main chain. The polymer (P) does not have an etheric oxygen (-O-), sulfonyl (-S(=O)2-), or carbonyl (-C(=O)-) skeleton in the main chain skeleton, and is therefore excellent in chemical durability, particularly alkali durability. The aromatic ring here refers to the aromatic ring that constitutes the main chain, and the aromatic ring that constitutes the main chain may further have an aromatic ring as a substituent. The aromatic ring that constitutes the main chain and the aromatic ring that is contained as a substituent (side chain) are to be distinguished.

[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 preferably a sulfonic acid group (-SO3H group), a phosphoric acid group (-H2PO4 group), or a carboxylic acid group (-COOH group), with the sulfonic acid group being more preferred. Note that the H in the acidic group may be dissociated or substituted with an alkali metal ion, alkaline earth metal ion, or the like.

[0023] Furthermore, when anion conductivity is to be 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 those 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 formulae (e-1) to (e-8): Preferred specific examples of the imidazolium group include a group represented by the following formula (f-1), with a group represented by the following formula (f-2) or a group represented by the following formula (f-3) being more preferred.

[0024] [ka] In the formula, R e are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and R f are 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. The wavy lines in the formula indicate Ar 1 The bond bonded to the aromatic ring that constitutes the main chain is shown.

[0025] 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 or the like, and the substituent of the phenyl group may be an alkyl group having 1 to 6 carbon atoms or the like.

[0026] Above A - The anion is preferably an inorganic anion, and a chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), bicarbonate ion (HCO3 - ), carbonate ions (CO3 2-), hydroxide ion (OH - ), sulfate ions (SO4 2- ), chlorate ion (ClO3 - ), nitrate ions (NO3 - ), cyanide ion (CN - ), sulfite ions (HSO3 - ), bromate ion (BrO3 ― ), fluorine ion (F - Among these, hydroxide ions (OH - ), bromide ion (Br - ), bromate ion (BrO3 ― ), chloride ions (Cl - ), bicarbonate ion (HCO3 - ), carbonate ions (CO3 2- ), and particularly preferably hydroxide ion (OH - ), bromide ion (Br - ), chloride ions (Cl - ), bicarbonate ion (HCO3 - ), carbonate ions (CO3 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. The organic group is preferably a linear or branched alkylene group, and particularly preferably a linear alkylene group. The number of carbon atoms in the alkylene group can be appropriately adjusted depending on the physical properties required of the polymer (P). For example, by adjusting the carbon number 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 adjusting the carbon number of the alkylene group to 2 or more, preferably 4 or more, and more preferably 6 or more, the solubility and swelling resistance are excellent, and the polymer (P) can be easily filled into a porous substrate. Ar 1The number of ion exchange groups per aromatic ring constituting the main chain in the polymer may be one or more, and from the viewpoints of ion conductivity and polymer stability, one to two are preferred.

[0028] Ar 1 The 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 methyl, ethyl, propyl, n-butyl, tert-butyl, pentyl, hexyl, and octyl, 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 alkyl groups having 1 to 6 carbon atoms, halogeno groups, and the like. Furthermore, examples of the halogeno group include a fluoro group, a chloro group, a bromo group, and an iodo group.

[0030] The polymer (P) is preferably selected from the group consisting of Ar and Ar-based polymers, because of its excellent mechanical strength, chemical durability, and ionic conductivity. 1 is preferably a group represented by any one of the following formulae (a-1) to (a-10). In addition, there are multiple Ar 1 may be the same as or different from each other.

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

[0032] Ar 2 The 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 the above may be the same as those in the above. 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). Also, 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 polymer filling ability into porous substrates, Ar 2 Preferably, does not have a spiro atom.

[0033] [ka] 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 adjusted appropriately 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 the Ar 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] [ka] 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 the 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 anion-exchange group-containing Ar 1 and spirobifluorene skeletons are alternately repeated. The polymer (P1) has a structure in which each element constituting the main chain skeleton belongs to an aromatic ring or is a spiro atom with 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. This reduces the planarity of the main chain, inhibiting π-π stacking, resulting in excellent solubility in solvents and excellent handling 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] [ka] In Scheme A1, R a represents an anion exchange group, and 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 Compound (C) having a brominated spirobifluorene skeleton is synthesized from compound (B) having the formula (i) to (vii). Separately, compound (C) having a desired aromatic ring (a benzene ring in the example of Scheme A1) is reacted with bis(pinacolato)diborane to form Ar in general formula (1-1). 1 (Step (viii)) is used to synthesize compound (E), which is a precursor of the above. After polymerizing compound (C) and compound (E), 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 by referring to known reactions.

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

[0045] [ka] 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) 2Among 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] [ka] where R is Ar 2 is a substituent that may be present, 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 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. The following formula is a representative example: 2 As shown in the formula below, the polymer (P2) tends to have a zigzag main chain structure, and 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] [ka]

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

[0052] [ka] However, R b2is an anion exchange group, and p2 is an integer of 1 to 20. The wavy line indicates a bond to the benzene ring.

[0053] The above formula (R a In the group represented by (P2-1), the carbon atom adjacent to the benzene ring that constitutes the main chain is a quaternary carbon. Therefore, π-π stacking between polymers (P2) is suppressed. As a result, aggregation of polymer (P2) is suppressed, making it more soluble in solvents and easier to handle during film formation. p2 is {(R b2 It 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] [ka] However, X, X 1 represents a halogen atom, and Ar 2 , and p2 are as described above. X 1 The halogen atom is preferably Br.

[0056] In the example of Scheme A2 above, 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 the above scheme A2, 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 by referring to known reactions.

[0057] Polymer (P3) The polymer (P3) contains a repeating unit represented by the general formula (1) in which Ar2 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] [ka]

[0059] The polymer (P3) is an anion-exchange group-containing Ar 1 and Ar having a partial structure (2) containing a fluoro group (-F). 2 The main chain consists of Ar 1 and Ar 2 Each of these has an aromatic group, and is highly chemically resistant to alkalis and radicals. Polymer (P3) also has an Ar group with an ion exchange group linked to the end of the side chain via an alkyl chain. 1 and Ar without ion exchange groups 2 are arranged alternately. This structure provides excellent solubility in solvents and ionic conductivity. In addition, the reactivity of the compound having partial structure (2) with the compound represented by formula (4) described below is high, 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 membrane with superior durability.

[0060] Ar 2For example, as in the formula (b-1) described later, one ring structure (e.g., a benzene ring) may have two partial structures (2), or as in the 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 the Ar and Ar-based polymers, because it has excellent ionic conductivity and film-forming properties, and can form an electrolyte membrane having excellent chemical durability and film strength. 2 is preferably one or more selected from the following formulae (d1) to (d9). 1 This shows the bond between .

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

[0063] 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 Examples of the organic group include linear or branched alkyl groups having 1 to 20 carbon atoms (not including the carbon atoms 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] [ka]

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

[0069] [ka]

[0070] In Scheme A3 above, first, the desired Ar 3 and a compound (4) having the desired Ar 2 Then, these compounds are reacted in a solvent, for example, in the presence of a Pd complex, a ligand, a carboxylic acid (RCOH), and a base at 80 to 140°C for 1 to 48 hours to obtain a polymer having structural unit (3).

[0071] Next, the desired ion-exchange group is introduced into the polymer having the structural unit (3) to obtain the polymer (P3). In this way, the polymer (P3) can be easily produced with very few synthetic 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] [ka] 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 that has aromatic properties as a whole, and Ar 1 is the same as in the general formula (1).

[0074] The polymer (P4) is an anion-exchange group-containing Ar 1 and Ar consisting of three or more fused rings 2 Generally, polymers containing many ion exchange groups tend to swell easily, but polymer (P4) has a structure in which Ar 1 and Ar 2 and are alternately repeated, and condensed rings of three or more rings are π-π stacked, resulting in excellent swelling resistance.

[0075] Ring Ar 11 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 rings containing the following are preferably 3 or more fused rings. On the other hand, from the viewpoint of increasing the ion exchange capacity of the polymer (P4), fused rings containing 5 or less fused rings are preferred, and fused rings containing 4 or less fused rings are more preferred. Preferred specific examples of the fused ring include the following: 1 The hydrogen atom may be substituted with a group that does not have an anion exchange group.

[0076] [ka]

[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, and then eliminating the substituent (TL).

[0078] [ka] where LT is a group represented by general formulas (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). R 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). 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] [ka]

[0082] An example of each step in the above scheme A4 will be described. Step (i): A toluene solution of the compound (1) is prepared, diethyl azodicarboxylate (DEAD) is added, and the mixture is heated under reflux to obtain the compound (2). Step (ii): Separately, a solution of the compound (3) in N,N-dimethylformamide (DMF) is prepared, and bis(pinacolato)diborane, potassium acetate (KOAc), and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (Pd(dppf)Cl2) are added thereto, followed by heating to 90°C to obtain the compound (4). Step (iii): To a toluene solution of the obtained compound (2) and compound (4), tripotassium phosphate (K3PO4) and tetrakis(triphenylphosphine)palladium (Pd(PPH3)4) are added and the mixture is heated to 100°C to polymerize the compound, thereby obtaining 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 mixed solvent of DMF / THF (tetrahydrofuran) to obtain a precursor represented by the above 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, which can impart mechanical strength to the polyarylene polymer having excellent chemical durability. The porous substrate is a substrate having pores capable of holding a polymer, and it is preferable that at least some of the pores of the porous substrate form through-holes in order to improve ion conductivity. The substrate is preferably in the form of a nonwoven fabric or a porous film, more preferably in the form of a porous film, in terms of imparting mechanical strength. The porosity of the porous substrate (=void volume / bulk volume×100(%)) 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 ion conductivity. The 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 ion conductivity. The pore size of the porous substrate is preferably 10 to 10,000 nm, more preferably 10 to 1,000 nm, in terms of filling and holding 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 with 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., with a weight-average molecular weight of 1,000,000 or more) porous substrates are particularly preferred.

[0084] One 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 to fill the pores of the porous substrate, and then the 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 fabricating a pore-filling membrane using a polymer solution in an amount sufficient to fill 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 (A) an electrolyte membrane is coated with (B) a 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, which can be appropriately selected from known metals and metal alloys, such as platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, compounds of these metals, metal oxides, and alloys containing two or more of these metals. The cathode catalyst is preferably a metal or a metal alloy, which can be appropriately selected from known metals and metal alloys, such as 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 (B) catalyst layer of the present disclosure is preferably configured such that the above metal is dispersed in the (B-1) ionomer, from the viewpoints of adhesion to the (A) electrolyte membrane and an increased reactive specific surface area. (B-1) The ionomer may be a sulfonated fluoropolymer, such as a perfluorinated sulfonic acid (PFSA) ionomer, or a partially fluorinated polymer. 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 sufficient for use in the AEMWE method, in which a continuous change from a liquid to a gas state occurs. A more preferred lower limit of 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 ratio of the breaking stress of the (B) catalyst layer relative to the breaking stress of the (A) electrolyte membrane is 0.12 or more and 0.20 or less.

[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 carried out at 0.3 m / min using an EZ-SX (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). Particularly preferably, the same polymer as the polymer having an ion exchange group used in the (A) electrolyte membrane is used.

[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] [Creation 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, 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. 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 of 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 (A) electrolyte membrane 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 main surface of this electrolyte membrane 11 has a first catalyst layer 12 having a (B-1) ionomer 3 and a hydrogen generating catalyst 4, and a second main surface of the electrolyte membrane 11 has a second catalyst layer 13 having a (B-1) ionomer 3 and an oxygen generating catalyst 5.

[0093] Anion exchange membrane water electrolysis performance refers to the ability to electrolyze water without a large voltage rise when an alkaline solution is passed through an electrochemical cell that has a catalyst layer of metal powder with hydrogen generation ability dispersed in ionomer on the cathode side of an electrolyte membrane with anion exchange groups, and a catalyst layer of metal powder with oxygen generation ability dispersed in ionomer on the other anode side, and when a current is passed from a power source through the electrolyte membrane that has been ion-exchanged to OH ions by the alkaline solution, and the electrochemical cell that contains the ionomer. Specifically, carbon supported with platinum or carbon supported with platinum-ruthenium alloy is generally used as the hydrogen generation catalyst, while iridium oxide is generally used as the oxygen generation 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 At this time, the voltage may be 2.0V or less, preferably 1.7V to 1.8V, and particularly preferably 1.78V or less. The ion exchange capacity represents the amount of ions that an ion exchange resin can adsorb, and a higher value indicates higher ionic conductivity. In the electrolyte membrane (A) of the present disclosure, the ion exchange resin is a polymer having ion exchange groups. A higher ion exchange capacity results in higher ionic conductivity, but also in a higher water content, which causes the electrolyte membrane to swell and deteriorates its gas barrier properties. Therefore, 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. [Example]

[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)] A four-neck flask was charged with 600 mL of sodium hydroxide (200 g), n-tetrabutylammonium chloride (3.04 g), 1,10-dichlorodecane (1097 mmol), and 2,7-dibromofluorene (109.7 mmol). The two-neck flask was then charged with a syringe and stirred under nitrogen. The mixture was then reacted at 90°C under nitrogen for 90 minutes, after which the resulting reaction mixture was cooled to room temperature (25°C). The organic phase of 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] [Case 1-1] TIFF0007792554000022.tif49112

[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), Pd(dba) (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 stirred at 60°C for 30 minutes. The 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 under vacuum to obtain compound (1-2) with a molecular weight distribution of 4.88. The GPC results for this compound (1-2), shown in Figure 2, showed a peak end of 14.025 min, confirming the reduction in low molecular weight components.

[0099] [Case 1-2] TIFF0007792554000023.tif65112

[0100] [Synthesis of compound (1-3)] Compound (1-2) (2.07 g) was dissolved in 3-methoxy-N,N-dimethylpropanamide (25 mL). A 25% by mass trimethylamine methanol solution (10 mL) was added to the resulting solution, and the mixture was stirred at 100°C for 9 hours. The mixture was then 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 under vacuum to obtain compound (1-3) (2.29 g). As mentioned above, compound (1-2) was synthesized to minimize the amount of low-molecular-weight compounds, and therefore, compound (1-3) is presumed to similarly contain minimal low-molecular-weight compounds.

[0101] [Case 1-3] TIFF0007792554000024.tif64112

[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 substrate. The solvent was then 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 the breaking stress of the electrolyte membrane> The electrolyte membrane 1 was cut into a size of 1.5 mm x 50 mm, and subjected to a uniaxial tensile test at 0.3 m / min using an EZ-SX (Shimadzu Corporation) at 25°C and 40% RH. The fracture stress was calculated from the cross-sectional area of ​​the fractured surface. The results are shown in Table 1.

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

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

[0106] [Table 2]

[0107] <Ion exchange capacity test> Using 1-4 and 50 mg of electrolyte membranes, immersion in a 1 mol / L sodium nitrate aqueous solution was performed at 25°C for 24 hours. After sufficient ion exchange of chloride ions and nitrate ions in the electrolyte membranes had occurred, potentiometric titration was performed with a 0.02 mol / L silver nitrate aqueous solution. The ion exchange capacity was calculated from the titration volume up to the inflection point and the weight of the electrolyte membrane. For the purpose of anion exchange, electrolyte membranes 2 to 4 were immersed in an aqueous sodium chloride solution for 48 hours, and then subjected to potentiometric titration using the method described above. The titration was performed using a COM-A19 made by Hiranuma Corporation. 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 a volume 1.1 times the void volume calculated from the porosity and thickness of each porous substrate. Electrolyte membranes 1 with different thicknesses were then fabricated, and similar tests were performed. 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)×TF×C1×K1 / S EP1: Titration volume required to reach the first endpoint (mL) BL1: Titration volume required for blank test (mL) TF: titrant factor (1.0003) C1: Concentration conversion factor (0.0001 mol / mL) K1: Unit conversion factor (1000) S...Amount of sample collected (g)

[0108] [Table 3]

[0109] [Example 1: Catalyst coated electrolyte membrane 1] The compound represented by Chemical Formula 1-3 was dissolved in a solvent (a mixed solution 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. Furthermore, ionomer solution 2 was obtained in the same manner, except that iridium oxide (Premion: manufactured by THERMO SCIENTIFIC CHEMICALS) was used in place of the carbon carrying platinum ruthenium. The electrolyte membrane 1 was coated with the ionomer solution 1 by spray coating and dried at 80° C. Subsequently, the opposite surface was coated with the ionomer solution 2 by spray coating and dried at 80° C., thereby obtaining 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, with the ionomer / carbon ratio adjusted to 0.5, so that 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-rays so that the iridium loading in the coated catalyst was 1.5 mg / cm2.

[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 membranes 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. 2 The measurement results are shown in Table 4. This voltage value was calculated by taking measurements every second for three minutes and averaging 60 pieces of data from 2 minutes 1 second to 3 minutes 0 seconds. [Table 4]

[0112] <Alkali durability test> The same immersion test in a 1 M potassium hydroxide aqueous solution 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. [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. [Industrial Applicability]

[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 in its entirety. [Explanation of symbols]

[0116] 1: Polymer having ion exchange groups (electrolyte polymer), 2: Base 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, a catalyst-coated electrolyte membrane having anion exchange membrane-based water electrolysis performance, wherein the (B) catalyst layer contains an (B-1) ionomer, and the ionomer has a breaking stress that is 0.01 or more and 0.5 or less relative to the breaking stress of the (A) electrolyte membrane;

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

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

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

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

6. 3. The catalyst coated electrolyte membrane according to claim 1, wherein the electrolyte membrane (A) has a pore filling structure.

7. 3. The catalyst coated electrolyte membrane according to claim 1, wherein the electrolyte membrane (A) contains a polymer having a structural unit represented by the following formula (1): [Chemical 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 The aromatic ring contained in and the aromatic ring contained in Ar2 are linked via a single bond.

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