Catalyst-coated electrolyte membrane

Abstract

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

Description

Technical Field

[0001] The present invention relates to a catalyst-coated electrolyte membrane for water electrolysis, and more specifically, to a catalyst-coated electrolyte membrane that uses an anion exchange membrane (AEM) as the electrolyte membrane and coats it with a catalyst layer. Background Technology

[0002] Electrolyte membranes are used in various fuel cells, such as solid polymer 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 ion conductivity and durability to withstand long-term use.

[0003] In water electrolysis, the anion exchange membrane electrolysis method (AEMWE method) has been proposed as an alternative to the cation exchange membrane electrolysis method and the alkaline water electrolysis method, and has received widespread attention in recent years. This method uses an anion exchange membrane (AEM) as the membrane separating the anode and cathode chambers, and supplies pure water or an alkaline aqueous solution to the anode chamber as the anolyte. Pure water or an alkaline aqueous solution can be supplied to the cathode chamber as the electrode solution, or a dry cathode electrolyzer can be used without supplying an electrode solution to the cathode chamber. In the case of the dry cathode electrolyzer, water permeates from the anode chamber to the cathode chamber through the anion exchange membrane, thus supplying water to the cathode chamber. In the cathode chamber, hydrogen gas and hydroxide ions are generated from water through a cathode reaction.

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

[0005] For example, Patent Document 1 discloses a water electrolyzer structure for the AEMWE process. When using this structure for water electrolysis, applying excessive pressure from the anode chamber to the cathode chamber can load the CCM. Therefore, high requirements are placed on the durability of the CCM.

[0006] In addition, unlike cation exchange membrane water electrolysis and alkaline water electrolysis, a continuous state change from liquid to gas occurs between the catalyst layer or ionomer layer and the electrolyte membrane, thus further increasing the mechanical strength requirements for CCM.

[0007] Patent document 2 discloses an anion-conductive polymer for electrolyte membranes that has excellent chemical durability and excellent solvent solubility. The polymer has a structure in which divalent aromatic groups of ionic functional groups and spirodifluorene skeletons are alternately repeated.

[0008] However, Patent Document 2 only evaluated its application in fuel cells where the problems specific to the AEMWE method do not need to be considered, and it has not yet clarified what level of strength can solve the problems specific to the AEMWE method. Furthermore, guidelines for improving which properties of the electrolyte membrane or catalyst layer should be improved to enhance mechanical strength, thereby improving the adhesion of the contact surfaces of each layer, are also unclear.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: International Publication No. 2022 / 244805;

[0012] Patent Document 2: Japanese Patent Application Publication No. 2018-135487. Summary of the Invention

[0013] The problem the invention aims to solve

[0014] In view of the above, the objective of the present invention is to provide a catalyst-coated electrolyte membrane that exhibits low voltage, excellent water electrolysis performance, and excellent mechanical strength in anion exchange membrane-type water electrolysis experiments.

[0015] Technical solutions for solving the problem

[0016] Through in-depth research, the inventors discovered that focusing on the tensile fracture stress of the electrolyte membrane can solve the above-mentioned problems.

[0017] That is, the present invention relates to the following 1) to 9).

[0018] 1) A catalyst-coated electrolyte membrane, comprising:

[0019] (A) An electrolyte membrane with a fracture stress of 85 MPa or higher; and

[0020] (B) Catalyst layer.

[0021] 2) The catalyst-coated electrolyte membrane according to 1) above, wherein the electrolyte membrane (A) above comprises a polymer having anion exchange groups.

[0022] 3) The catalyst-coated electrolyte membrane described in 1) or 2) above has anion exchange membrane water electrolysis performance.

[0023] 4) A catalyst-coated electrolyte membrane according to any one of 1) to 3) above, wherein the electrolyte membrane (A) contains a polymer (A-1) that does not have ion conductivity.

[0024] 5) A 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.

[0025] 6) A catalyst-coated electrolyte membrane according to any one of 1) to 5) above, wherein the catalyst layer (B) contains an ionomer (B-1), and the fracture stress of the ionomer is 0.01 or more and 0.5 or less relative to the fracture stress of the electrolyte membrane (A).

[0026] 7) The catalyst-coated electrolyte membrane according to 6) above, wherein the ionomer of (B-1) above contains the same polymer as the polymer used in the electrolyte membrane of (A) above.

[0027] 8) A catalyst-coated electrolyte membrane according to any one of 1) to 7) above, wherein the electrolyte membrane (A) above has a pore-filled structure.

[0028] 9) A catalyst-coated electrolyte membrane according to any one of 1) to 8) above, wherein the electrolyte membrane (A) comprises a polymer having a structural unit as shown in formula (1) below.

[0029]

[0030] In equation (1),

[0031] Ar 1 It is an aromatic group with an ion-exchange group, or a group consisting of an aromatic ring with an ion-exchange group linked by a single bond, and multiple Ar groups. 1 They can be the same or different;

[0032] Ar 2 It is an aromatic group without an ion-exchange group, or a group consisting of two or more aromatic rings without an ion-exchange group connected by a single bond or spiro atom, with multiple Ar atoms. 2 They can be the same or different;

[0033] Ar 1 The aromatic ring it possesses is similar to Ar 2 The aromatic rings it possesses are connected by single bonds.

[0034] Invention Effects

[0035] According to the present invention, a catalyst-coated electrolyte membrane can be provided that exhibits low voltage and excellent water electrolysis performance in anion exchange membrane-type water electrolysis tests, and has sufficiently high durability to the point that it is not problematic even when used in the AEMWE process. Attached Figure Description

[0036] Figure 1 This is a diagram illustrating an example of the layer structure of the catalyst-coated electrolyte membrane of this embodiment.

[0037] Figure 2 This is a diagram illustrating another example of the layer structure of the catalyst-coated electrolyte membrane of this embodiment. Detailed Implementation

[0038] The following describes an example of an embodiment of the present invention. Specific numerical values ​​in this specification are values ​​obtained through the methods disclosed in the embodiments or examples. Other embodiments are also included within the scope of the present invention, provided they conform to its spirit. Furthermore, in this invention, the term "~" indicating a numerical range means that the values ​​described before and after it are included as a lower limit and an upper limit.

[0039] The catalyst-coated electrolyte membrane of the present invention comprises: (A) an electrolyte membrane with a fracture stress of 85 MPa or more (hereinafter also referred to as (A) electrolyte membrane); and (B) a catalyst layer.

[0040] Figure 1 An example of the layer structure of the catalyst-coated electrolyte membrane of this embodiment is shown. The catalyst-coated electrolyte membrane 100, as shown, includes an electrolyte membrane 11, a first catalyst layer 12 formed on the first main surface side of the electrolyte membrane 11, and a second catalyst layer 13 formed on the second main surface side of the electrolyte membrane 11. In the catalyst-coated electrolyte membrane of this embodiment, the electrolyte membrane 11 is composed of an electrolyte membrane with a fracture stress of 85 MPa or more (A). Furthermore, Figure 1 In the example, the first catalyst layer 12 and the second catalyst layer 13 are the (B) catalyst layers of the present invention. Alternatively, either the first catalyst layer 12 or the second catalyst layer 13 can be the (B) catalyst layer, while the other can be a catalyst layer that is not part of the (B) catalyst layer. It can also be a catalyst-coated electrolyte membrane with a catalyst layer formed only on one main surface of the electrolyte membrane 11. That is, the catalyst-coated electrolyte membrane of the present invention only requires that the (B) catalyst layer be formed on at least one side of the (A) electrolyte membrane. Hereinafter, the (A) electrolyte membrane and the (B) catalyst layer will be described.

[0041] [(A) Electrolyte membrane with a fracture point stress of 85 MPa or higher]

[0042] The present invention uses an electrolyte membrane with a fracture point stress of 85 MPa or higher (A).

[0043] <(A) Electrolyte membrane>

[0044] (A) An electrolyte membrane is a membrane containing a polymer having ion exchange groups. Preferred examples include: (i) a membrane composed of a polymer having ion exchange groups; and (ii) a membrane formed by impregnating a polymer having ion exchange groups into a porous substrate. The porous substrate is a membrane having a so-called pore-filled structure, and examples include pore-filled substrate membranes, nonwoven fabrics, etc. Here, the pores can be selected, for example, submicron size, micron size, etc. The pores only need to be connected in the thickness direction of the substrate membrane, and are not limited to a substrate membrane with pores formed in the thickness direction.

[0045] In this specification, "polymer" includes "copolymer" unless otherwise specified. Furthermore, "ion exchange group" refers to a functional group that is dissociable and capable of ion exchange. Anion exchange groups are preferred as "ion exchange groups." Anion exchange groups are substituents with cations, such as groups where heteroatoms are cationized. Examples of anion exchange groups include quaternary ammonium salts, imidazolium salts, pyridinium salts, and phosphonium salts.

[0046] (Stress at the fracture point)

[0047] The fracture point stress of the electrolyte membrane (A) used in this invention is above 85 MPa.

[0048] The fracture point stress is a value determined according to the measurement method shown below.

[0049] Measurement method:

[0050] 1) Preparation of test pieces

[0051] In case (i), the polymer with ion-exchange groups is coated and dried to form a self-supporting film. In case (ii) above, the polymer with ion-exchange groups is filled or impregnated into the pores of the substrate film. As the substrate film, a polymer without ion conductivity is preferably used.

[0052] In case (i) above, for example, a polymer with ion-exchange groups is dissolved in a solvent to prepare a solution, which is then dropped onto a release membrane. The solvent is removed to produce a membrane with a thickness of approximately 10–40 μm. The release membrane is then removed. The resulting membrane is cut into 3 mm × 50 mm pieces as test pieces.

[0053] In the case described in (ii) above, a polymer with ion-exchange groups is dissolved in a solvent to prepare a solution. This solution is then dropped onto a porous substrate membrane. The solvent is removed, thereby creating a membrane in which the pores of the substrate membrane are filled with the polymer having ion-exchange groups. The thickness of the substrate membrane is preferably 10–40 μm. The resulting membrane is then cut into 3 mm × 50 mm pieces as test pieces. Furthermore, as the substrate membrane, polyolefin membranes such as polyethylene, polypropylene, and polytetrafluoroethylene (PTFE) are preferred, as are amide-based membranes such as polyimide and polyamide, and polyolefin membranes are more preferred. The pore size is preferably submicron in size.

[0054] 2) Determination of stress at the fracture point

[0055] The prepared test specimens were subjected to uniaxial tensile tests at 0.3 m / min in an environment of 25°C and 40%RH using an EZ-SX (manufactured by Shimadzu Corporation). The stress at the fracture point was calculated based on the cross-sectional area of ​​the fracture surface.

[0056] In addition, when the strain of the test piece is too large and exceeds the measurement limit, a test piece of 1.5mm × 50mm can be used.

[0057] The lower limit of the fracture point stress is 85 MPa, and more preferably 90 MPa, 95 MPa, 100 MPa, 115 MPa, 120 MPa, and 125 MPa, with 130 MPa being particularly preferred. Furthermore, the upper limit is determined based on its relationship with other components and cannot be generalized; for example, around 200 MPa is acceptable, with 150 MPa being particularly preferred. Therefore, the most preferred fracture point stress is 125 MPa or higher and 150 MPa or lower.

[0058] (polymer)

[0059] The polymer with ion-exchange groups used in the electrolyte membrane of (A) of the present invention is preferably a polyarylene polymer. By using a polyarylene polymer, an electrolyte membrane with excellent chemical durability can be obtained.

[0060] Furthermore, from the viewpoint of imparting excellent ion conductivity to the pore-filled membrane, polyarylene polymers are preferably polymers having the structural units shown in the following general formula (1) (hereinafter also referred to as polymer (P)).

[0061]

[0062] In equation (1),

[0063] Ar 1 It is an aromatic group with an ion-exchange group, or a group consisting of an aromatic ring with an ion-exchange group linked by a single bond, and multiple Ar groups. 1 They can be the same or different;

[0064] Ar 2 It is an aromatic group without an ion-exchange group, or a group consisting of two or more aromatic rings without an ion-exchange group connected by a single bond or spiro atom, with multiple Ar atoms. 2 They can be the same or different;

[0065] Ar 1 The aromatic ring it possesses is similar to Ar 2 The aromatic rings it possesses are connected by single bonds.

[0066] Polymer (P) is a polymer having two or more of the above-described structural units (1), having the following structure: Ar with ion exchange groups 1 With Ar that does not have ion exchange groups 2 An alternating configuration structure. 1 The aromatic groups it contains and Ar 2 The aromatic groups are bonded together via single bonds to form the main chain. The polymer (P) lacks ether oxygen (-O-), sulfonyl (-S(=O)2-), and carbonyl (-C(=O)-) skeletons in its main chain backbone, exhibiting excellent chemical durability, particularly alkali resistance. Furthermore, the aromatic rings mentioned in this specification refer to the aromatic rings constituting the main chain, which may further contain aromatic rings as substituents. The aromatic rings constituting the main chain are distinct from those present as substituents (side chains).

[0067] Ar 1 It is an aromatic group with an ion-exchange group, or a group consisting of an aromatic ring with an ion-exchange group connected by a single bond.

[0068] When imparting proton conductivity to polymer (P), the ion exchange group is preferably an acidic group, and among the acidic groups, a sulfonic acid group (-SO3H group), a phosphate group (-H2PO4 group), or a carboxylic acid group (-COOH group) is preferred, with a sulfonic acid group being more preferred. In addition, the H in the above-mentioned acidic group can dissociate or be replaced by alkali metal ions, alkaline earth metal ions, etc.

[0069] Furthermore, when imparting anionic conductivity to the polymer (P), the ion exchange group is preferably a quaternary ammonium group or an imidazolium group, more preferably a quaternary ammonium group. Moreover, from the viewpoint of alkali resistance, the aforementioned quaternary ammonium group is preferably a quaternary alkylammonium group. Additionally, this quaternary alkylammonium group also includes groups that form a ring structure by bonding alkyl groups bonded to each other with nitrogen atoms, such as azadamaneyl groups, quinine cycloyl groups, etc.

[0070] Preferred examples of the aforementioned quaternary ammonium group include the groups shown in formulas (e-1) to (e-8) below. Furthermore, preferred examples of the imidazole onium group include the group shown in formula (f-1) below, and even more preferred are the groups shown in formula (f-2) or formula (f-3) below.

[0071]

[0072] In the formula, R e Each is independently a straight-chain, branched, or cyclic alkyl group having 1 to 6 carbon atoms; R f Each is independently a hydrogen atom, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, or an aromatic group that may have substituents; A - It is a monovalent or divalent or higher anion; when multiple R are present e or R f At that time, the multiple R e or R f They can be the same or different. Additionally, the wavy line in the formula represents Ar. 1 The aromatic rings that make up the main chain are bonded to the sides.

[0073] As mentioned above, R e Specific examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, etc. As for the aforementioned R... f Specific examples of alkyl groups include methyl, ethyl, propyl, butyl, etc. Furthermore, as R... f Aromatic groups in phenyl groups can be exemplified by phenyl groups, and alkyl groups having 1 to 6 carbon atoms can be exemplified by substituents for phenyl groups.

[0074] As for the above A - Preferably, it is an inorganic anion, such as chloride ion (Cl). - ), bromide ions (Br) - ), iodide ions (I) - ), bicarbonate ions (HCO3) - ), carbonate ions (CO3) 2- ), hydroxide ions (OH-) - ), sulfate ions (SO4) 2- ), chlorate ions (ClO3) - ), nitrate ions (NO3) - ), cyanide ions (CN) - ), sulfite ions (HSO3) - ), bromate ions (BrO3) - ), fluoride ions (F) - ), etc. Among them, hydroxide ions (OH-) are preferred. - ), bromide ions (Br) - ), bromate ions (BrO3) - ), chloride ions (Cl) - ), bicarbonate ions (HCO3) - ), carbonate ions (CO3) 2-), with a particular preference for hydroxide ions (OH-). - ), bromide ions (Br) - ), chloride ions (Cl) - ), bicarbonate ions (HCO3) - ), carbonate ions (CO3) 2- ).

[0075] The above-mentioned ion exchange groups can be directly bonded to Ar. 1 The aromatic ring constituting the main chain of the polymer (P) may further have a linker group and be bonded to the aromatic ring constituting the main chain via the linker group. Here, the linker group refers to 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, more preferably a linear alkylene group. The number of carbon atoms of the alkylene group can be appropriately adjusted according to the desired physical properties of the polymer (P). For example, setting the number of carbon atoms of the alkylene group to 20 or less, preferably 16 or less, more preferably 12 or less, can improve the ion exchange capacity of the polymer (P). On the other hand, setting the number of carbon atoms of the alkylene group to 2 or more, preferably 4 or more, more preferably 6 or more, can result in excellent solubility and swelling resistance, making it easier to fill the polymer (P) into a porous substrate.

[0076] Ar 1 Each aromatic ring constituting the main chain has one or more ion exchange groups, and from the viewpoint of ion conductivity and polymer stability, one to two are preferred.

[0077] Ar 1 Besides benzene rings, the aromatic rings constituting the main chain can be fused rings such as naphthalene rings and anthracene rings, or heterocycles containing oxygen (O), nitrogen (N), and sulfur (S) atoms (e.g., thiophene). Furthermore, they can also be structures formed by these aromatic rings linked by single bonds. Examples of structures formed by multiple rings linked by single bonds include biphenyl, terphenyl, and fluorene.

[0078] Ar 1 In addition to the ion exchange group mentioned above, the aromatic ring constituting the main chain may also have substituents other than the ion exchange group. Examples of such substituents include alkyl groups with 1 to 20 carbon atoms, phenyl groups, halogen groups, etc.

[0079] Specific examples of the aforementioned alkyl groups include methyl, ethyl, propyl, n-butyl, tert-butyl, pentyl, hexyl, octyl, etc., and they may also have phenyl, halogen, etc., as substituents. The substituents that the aforementioned phenyl group may have include alkyl groups having 1 to 6 carbon atoms, halogen groups, etc. The aforementioned halogen groups include fluoro, chloro, bromo, iodo, etc.

[0080] From the perspective of excellent mechanical strength, chemical durability, and ionic conductivity, the above-mentioned Ar in polymer (P) 1 Particularly preferred are the groups shown in any one of the following formulas (a-1) to (a-10).

[0081] Multiple Ars exist in the polymer 1 At the same time, they can be the same or different.

[0082]

[0083] In the formula, Ra can be independently a hydrogen atom, an ion exchange group, or a substituent without an ion exchange group; when multiple Ra exist, they can be the same or different; at least one Ra is an ion exchange group. The wavy line represents the relationship with Ar. 2 Bonded bonds.

[0084] Ar 2 The aromatic rings that constitute the main chain can be listed as those of Ar mentioned above. 1 The same group and groups formed by spiro atom linkage. Ar 2 The aromatic ring in the atom can have substituents other than anion exchange groups. Other substituents can be listed in the Ar group mentioned above. 1 The same substituent group as the ion exchange group in the group.

[0085] Ar 2 Groups consisting of two or more aromatic rings linked by spirochetes can be exemplified by, for example, the group shown in formula (c1) below. Groups consisting of two or more aromatic rings linked by single bonds can be exemplified by, for example, the groups shown in formulas (c2) to (c4) below. The wavy line indicates a group related to Ar. 1 Bonded bonds. From the perspective of the filling effect of polymers on porous substrates, Ar 2 Preferably, it does not have a spiro atom.

[0086]

[0087] In the formula, R C Each can be independently a hydrogen atom, a halogen group, or an organic group.

[0088] The weight-average molecular weight of polymer (P) can be appropriately adjusted from the perspectives of chemical durability and ease of filling into fine pores, and can be set in the range of 10,000 to 1,000,000. From the viewpoint of chemical durability, a weight-average molecular weight of 30,000 or higher is preferred, and a weight-average molecular weight of 100,000 or higher is more preferred. In particular, when the porous substrate is a polyolefin-based porous substrate, even if the weight-average molecular weight of polymer (P) is 100,000 or higher, it is easy to fill into the fine pores. The weight-average molecular weight is a polystyrene conversion value determined by GPC (gel permeation chromatography).

[0089] The polymer (P) may consist only of the structural units shown in general formula (1) (also called structural unit (1)), or it may have other structural units. Other structural units can be listed as, for example, Ar of structural unit (1). 1 Structures without anion exchange groups may be included. Other structures that may arise during synthesis may also be included.

[0090] Polymer (P) is particularly preferred from the following polymers (P1) to (P4). From the viewpoint of the polymer's filling property in porous substrates, polymer (P2), polymer (P3), or polymer (P4) is preferred, polymer (P2) or polymer (P3) is more preferred, and further, from the viewpoint of the polymer's filling property, mechanical strength, and chemical durability, polymer (P3) is preferred. These polymers will be described in detail below.

[0091] Polymer (P1)

[0092] The polymer (P1) has repeating units as shown in the following general formula (1-1).

[0093]

[0094] In the formula, R 1 ~R 10 Each is independently a hydrogen atom, an alkyl group or a phenyl group having 1 to 4 carbon atoms; Ar 1 The preferred method is the same as that defined in equation (1) above.

[0095] R 1 ~R 10 Alkyl groups having 1 to 4 carbon atoms can be exemplified by methyl, ethyl, propyl, tert-butyl, etc. From the viewpoint of improving solubility, R is preferred in polymer (P1). 1 and R 10 At least one of them is an alkyl group, more preferably R 1 and R 10 All are alkyl groups, with R being a further preferred option. 1 and R 10 All are tert-butyl. (Used via R...) 1 and R 10 At least one of them has a large substituent, which can suppress polymer aggregation caused by π-π stacking and improve solubility in solvents. On the other hand, R 1 ~R 8 Each is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0096] Polymer (P1) has the following structure: Ar with anion exchange groups 1The polymer (P1) features an alternating structure with a spirodifluorene backbone. The elements constituting the main chain backbone are aromatic rings or spiro atoms without hydrogen atoms. Because the main chain backbone lacks ether bonds, decomposition in the presence of bases and free radicals is suppressed, resulting in excellent chemical durability. The spirodifluorene backbone has two fluorene atoms twisted at approximately right angles via spiro atoms. Since this fluorene backbone forms the main chain, the main chain exhibits numerous bends. Therefore, the planarity of the main chain is reduced, π-π stacking is hindered, solvent solubility is excellent, and it offers excellent workability when filling porous substrates.

[0097] There are no particular limitations on the synthesis method of polymer (P1), but preferred examples can be listed in the following scheme A1.

[0098]

[0099] In scheme A1, R a R represents anion exchange group. b In general formula (1-1), R represents... 1 and R 10 The corresponding substituents.

[0100] In the example of scheme A1, from the desired substituent R b Compound (B) is synthesized into compound (C) having a brominated spirodifluorene skeleton (steps (i) to (vii)). Additionally, bromide (D) having the desired aromatic ring (a benzene ring in the example of scheme A1) is reacted with bis(pinacolyl)diborane to synthesize Ar as in general formula (1-1). 1 Precursor compound (E) (step (viii)). After polymerizing the above compound (C) with the above compound (E), a desired anion exchange group is introduced to obtain the polymer shown in general formula (1-1) (steps (ix) to (xi)). The reaction conditions for each of the above steps can be determined with reference to known reactions.

[0101] Polymer (P2)

[0102] The polymer (P2) has repeating units as shown in the following general formula (1-2).

[0103]

[0104] In the formula, R a It is a group containing anion exchange groups; Ar 2 The definition is the same as that in the general formula (1) above.

[0105] Polymer (P2) is a polymer having two or more of the above-mentioned structural units (1-2), and its main chain is a fully aromatic compound. Due to this structure, polymer (P2) exhibits excellent durability against alkalis, free radicals, etc.

[0106] Ar in polymer (P2) 2 Particularly preferred are phenylene, biphenylene, and terphenylene, more preferably p-phenylene (Ar-1), 4,4'-biphenylene (Ar-2), or 4,4''-terphenylene (Ar-3).

[0107]

[0108] In the formula, R is Ar 2 It can have substituents; r is an integer from 0 to 4; multiple R and r can be the same or different.

[0109] When Ar 2 When the polymer is p-phenylene, 4,4'-biphenylene, or 4,4''-terphenylene, the main chain backbone of the polymer (P2) tends to have a zigzag configuration. The following formula representatively shows Ar... 2 For the case of phenylene, the same applies to 4,4'-biphenylene or 4,4''-terphenylene. As shown in the following formula, the main chain backbone of polymer (P2) tends to be arranged in a zigzag pattern, thus each R a It is easily configured on the outside of the bends in the backbone. Therefore, intramolecular aggregation caused by main chain bending is suppressed. As a result, it becomes a polymer capable of forming an electrolyte membrane with excellent ionic conductivity.

[0110]

[0111] The R group containing anion exchange groups in polymer (P2) a The following formula (R) is particularly preferred a -1) shows the group.

[0112]

[0113] In the formula, R b2 It is an anion exchange group; p2 is an integer greater than 1 and less than 20; the wavy line represents the bond with the benzene ring.

[0114] The above formula (R) a In the group shown in -1), the carbon atom adjacent to the benzene ring constituting the main chain is a quaternary carbon. Therefore, π-π stacking between polymers (P2) is suppressed. As a result, the aggregation of polymer (P2) is suppressed, it is easily soluble in solvents, and it has excellent operability during film formation, etc.

[0115] p2 represents {(from R)} b2 The number of carbon atoms in the quaternary carbon (to 1) can be appropriately adjusted within the range of 1 to 20. Preferably, it is 1 to 15, more preferably 1 to 12, and even more preferably 1 to 6.

[0116] There are no particular limitations on the synthesis method of polymer (P2), but preferred examples can be listed below in scheme A2.

[0117]

[0118] In the formula, X, X 1 Ar represents a halogen atom; 2 And p2 as described above. X 1 The preferred halogen atom is Br.

[0119] In the example of scheme A2 above, firstly, compound (H) and Ar are prepared. 2 Compound (I) is polymerized with compound (H) to obtain a polymer having the structural unit shown in (J). Next, a desired anion exchange group is introduced into polymer (J) to obtain polymer (P2). In scheme A2 described above, a quaternary ammonium group is introduced; other ionic functional groups can also be introduced using the same method. The reaction conditions for each of the above steps can be determined with reference to known reactions.

[0120] Polymer (P3)

[0121] In the repeating unit shown in the general formula (1) above, the polymer (P3) contains Ar 2 It has a partial structure at both ends as shown in equation (2). In other words, this Ar 2 Ar is a divalent group comprising an aromatic ring with a fluorine (-F) group at the α-position of the terminal carbon atom. 2 The end refers to the part with Ar 1 Bonded carbon atoms. The wavy line indicates the bond with Ar. 1 The bond is indicated by a dashed line, which shows that part of the aromatic ring has been omitted.

[0122]

[0123] Polymer (P3) has the following structure: Ar with anion exchange groups 1 Ar with a partial structure (2) containing a fluorine group (-F) 2 An alternating configuration structure. Ar constitutes the main chain. 1 and Ar 2 Each possesses an aromatic group, exhibiting excellent chemical durability against alkalis, free radicals, etc. In polymer (P3), Ar groups are present, with ion-exchange groups linked to the ends of the side chains via alkyl chains. 1 With Ar that does not have ion exchange groups 2Alternating configurations. Due to this structure, it exhibits excellent solubility in solvents and ionic conductivity. The compound having a portion of structure (2) is highly reactive with the compound shown in formula (4) described later, enabling the production of polymers with higher molecular weights. By using the above polymers with higher molecular weights, films with superior durability can also be formed.

[0124] Ar 2 For example, as in formula (b-1) described later, two partial structures (2) can be formed on a single ring structure (e.g., a benzene ring); or as in formula (b-2) described later, a single CF bond can constitute two partial structures (2). Furthermore, in the case of the above-described chain-like polycyclic hydrocarbons, each of the two ring structures possessed by the chain-like polycyclic hydrocarbon can have one partial structure (2), these rings being directly or via the aforementioned linking group; or two partial structures (2) can be formed on one of the multiple ring structures. Ar in polymer (P3) 2 Preferably, it does not have a spiro atom.

[0125] From the perspective of forming electrolyte membranes with excellent ion conductivity and film-forming properties, as well as excellent chemical durability and membrane strength, the polymer (P3) contains the aforementioned Ar... 2 Preferably, it is selected from one or more of the following formulas (d1) to (d9). The wavy line represents Ar. 1 Bonded bonds.

[0126]

[0127] In the formula, R d Each can be independently a hydrogen atom, a halogen group, or an organic group.

[0128] The above R d The halogen group in R can be fluorine, chloro, bromine, or iodine, with fluorine being preferred. d The organic groups in the form can be, for example, straight-chain or branched alkyl groups with 1 to 20 carbon atoms (excluding the number of carbon atoms) having substituents (e.g., halogen groups).

[0129] From the perspective of ease of manufacture, the aforementioned Ar 2 The preferred formulas are (d10) to (d14). The wavy line represents Ar. 1 Bonded bonds.

[0130]

[0131] There are no particular limitations on the synthesis method of polymer (P3), but preferred examples can be listed below for method A3.

[0132]

[0133] In the formula, X1 Each is independently either Br or I; Ar 3 It is an aromatic group having a functional group selected from halogen groups, sulfonate groups, phosphate groups, carboxylic acid ester groups, imidazole groups, and amino groups; Ar 2 Same definition as in polymer (P3).

[0134] X of compound (4) 1 Ar with compound (5) 2 The hydrogen atoms in the following partial structure (5a) exhibit excellent reactivity, thus enabling the relatively easy synthesis of high molecular weight (e.g., a weight-average molecular weight of 30,000 or more, preferably 100,000 or more) ion-conducting polymers.

[0135]

[0136] In the above scheme A3, firstly, prepare Ar with the desired Ar 3 Compound (4) and those with desired Ar 2 Compound (5). Then, for example, these compounds are reacted at 80–140 °C for 1–48 hours in a solvent, in the presence of a Pd complex, a ligand, a carboxylic acid (RCO2H) and a base, to obtain a polymer having structural unit (3).

[0137] Next, the desired ion exchange group is introduced into the polymer having structural unit (3) to obtain polymer (P3). Thus, polymer (P3) can be easily manufactured with very few synthetic steps using compounds (4) and (5) as raw materials.

[0138] Polymer (P4)

[0139] The polymer (P4) has repeating units as shown in the following general formula (1-4).

[0140]

[0141] In the formula, ring Ar 11 and the ring Ar 12 It is a ring fused with a benzene ring, and the whole is an aromatic fused ring of three or more rings; Ar 1 The definition is the same as that in the general formula (1) above.

[0142] Polymer (P4) has the following structure: Ar with anion exchange groups 1 Ar with fused rings of three or more rings 2 Alternating repeating structures. Polymers containing a large number of ion-exchange groups typically tend to swell easily, but in polymer (P4), Ar... 1 with Ar 2The alternating repetition and the stacking of fused rings with three or more rings through π-π stacking result in excellent resistance to swelling.

[0143] Ring Ar 11 and the ring Ar 12 This can be an aromatic ring containing heteroatoms. Examples of heteroatoms include N (nitrogen), O (oxygen), and S (sulfur). From the viewpoint of resistance to swelling, aromatic rings containing Ar... 11 and the ring Ar 12 The fused ring is preferably a fused ring with three or more rings. On the other hand, from the viewpoint of improving the ion exchange capacity of the polymer (P4), a fused ring with five or fewer rings is preferred, and a fused ring with four or fewer rings is more preferred.

[0144] The preferred specific example of this fused ring is as follows. The wavy line indicates the relationship with Ar. 1 Bonded bonds. Hydrogen atoms can be substituted by the aforementioned groups that do not have anion exchange groups.

[0145]

[0146] The polymer (P4) is preferably synthesized by preparing a precursor (1-5) having repeating units as shown in the following general formula (1-5), filling it into a porous substrate, and then removing the substituent (TL).

[0147]

[0148] In the formula, LT represents the group shown in general formulas (LT1) to (LT3); R 11 Each is an alkyl group having 1 to 6 carbon atoms; R 12 It is an alkyl or phenyl group having 1 to 6 carbon atoms; Ar 1 Ar 11 Ar 12 The definition is the same as that in the general formula (1-4) above.

[0149] R 11 and R 12 The alkyl group having 1 to 6 carbon atoms can be any of the straight-chain or branched alkyl groups. Specific examples include methyl, ethyl, propyl, n-butyl, tert-butyl, pentyl, hexyl, etc.

[0150] Polymer (P4) exhibits excellent resistance to swelling, as previously described. However, it suffers from poor solubility in various organic solvents and poor workability during processing. The aforementioned precursor incorporates a large substituent (TL) of the general formulas (LT1) to (LT3) at a site corresponding to the fused ring of polymer (P4), which is easily detachable by heat or light. In precursors (1-5), this substituent hinders the π-π stacking of the hydrophobic portion, improving solubility in various organic solvents. Therefore, the aforementioned precursor exhibits excellent workability and is easily incorporated into porous substrates. The substituent (TL) can be removed by heating or light irradiation.

[0151] The synthesis method of the above-mentioned precursor is not particularly limited, but preferred specific examples can be listed in the following scheme A4.

[0152]

[0153] An example of each step in the above scheme A4 will be provided.

[0154] Step (i): Prepare a toluene solution of the above compound (1), add diethyl azodicarbonate (DEAD) and heat under reflux to obtain the above compound (2).

[0155] Step (ii): Prepare an N,N-dimethylformamide (DMF) solution of the above compound (3), add bis(pinacolyl)diborane, potassium acetate (KOAc) and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (Pd(dppf)Cl2), and heat to 90°C to obtain the above compound (4).

[0156] Step (iii): Add tripotassium phosphate (K3PO4) and tetrakis(triphenylphosphine)palladium (Pd(PPH3)4) to a toluene solution of the obtained compound (2) and compound (4), and heat to 100°C to polymerize, thereby obtaining the above compound (5).

[0157] Step (iv): The obtained compound (5), N-bromosuccinimide (NBS) and azobisisobutyronitrile (AIBN) were added to chlorobenzene and mixed, and heated to 110°C to obtain the above compound (6).

[0158] Step (v): The obtained compound (6) was heated to 50°C in a DMF / THF (tetrahydrofuran) mixed solvent to obtain the precursor shown in the above chemical formula (7).

[0159] <Fine-pore filling membrane>

[0160] The electrolyte membrane used in this invention is preferably a fine-pore filled membrane with a porous substrate as the substrate membrane and filled with the aforementioned polymer. This structure imparts mechanical strength to the polyarylene polymer, which exhibits excellent chemical durability.

[0161] The aforementioned porous substrate refers to a substrate having pores capable of retaining polymer. From the viewpoint of improving ionic conductivity, it is preferable that at least a portion of the pores in the porous substrate are formed as through pores.

[0162] From the perspective of imparting mechanical strength, the substrate is preferably a nonwoven fabric or a porous membrane, and more preferably a porous membrane.

[0163] From the perspective of balancing mechanical strength and ion conductivity, the porosity (= void volume / apparent volume × 100 (%)) of the porous substrate is preferably 30 to 95%, more preferably 40 to 80%, and even more preferably 45 to 70%.

[0164] From the perspective of balancing mechanical strength and ion 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.

[0165] From the viewpoint of filling and maintaining polyarylene polymer and mechanical strength, the pore size of the porous substrate, measured in terms of average pore size, is preferably 10 to 10,000 nm, more preferably 10 to 1,000 nm.

[0166] From the viewpoint of chemical durability, especially stability in alkaline environments, polyolefin-based porous substrates are preferred. Using polyolefin-based porous substrates also offers the advantage of easy filling with polyarylene polymers, particularly high-molecular-weight polyarylene polymers with a weight-average molecular weight of 100,000 or higher. From the viewpoint of mechanical strength and chemical resistance, polyolefin-based porous substrates are preferably polyethylene, polypropylene, or polytetrafluoroethylene (PTFE) porous substrates. Ultra-high molecular weight polyethylene (e.g., with a weight-average molecular weight of 1 million or higher) porous substrates are particularly preferred.

[0167] One example of a method for manufacturing a fine-pore filled membrane is as follows: a polymer having ion-exchange groups (e.g., a polyarylene polymer) is applied to a porous substrate, which is then filled into the fine pores of the porous substrate and dried.

[0168] Methods for imparting polyarylene polymers to porous substrates include, for example, preparing a polyarylene polymer solution and coating it using methods such as dip coating, spray coating, spin coating, or rod coating. After the polyarylene polymer solution permeates into the porous substrate and is dried, an electrolyte membrane (A) consisting of a microporous filled membrane can be obtained. Regarding the thickness of the electrolyte membrane (A), for example, by using a polymer solution of an amount sufficient to satisfy the porosity volume of the porous substrate to manufacture the microporous filled membrane, the thickness can be set to be the same as that of the porous substrate. The presence of polyarylene polymer filling the porous substrate can be confirmed, for example, by Raman analysis.

[0169] [(B) Catalyst layer]

[0170] The catalyst-coated electrolyte membrane of the present invention has a structure in which (A) at least one side of the main surface of the electrolyte membrane is coated with (B) a catalyst layer. The electrolyte membrane for water electrolysis has an anodic catalyst disposed on one side as an anode and a cathode catalyst disposed on the other side as a cathode.

[0171] The anode catalyst is preferably a metal or a metal alloy. The metal or metal alloy can be appropriately selected from known materials, 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.

[0172] The cathode catalyst is preferably a metal or a metal alloy. The metal or metal alloy can be appropriately selected from known materials, 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.

[0173] <(B-1) Isopolymer>

[0174] From the viewpoint of good adhesion to the (A) electrolyte membrane and increasing the specific surface area of ​​the reaction, the (B) catalyst layer of the present invention is preferably composed of the above-mentioned metal dispersed in the (B-1) ionomer.

[0175] (B-1) Ionomers can be sulfonated fluoropolymers, such as perfluorinated sulfonic acid (PFSA) ionomers or partially fluorinated polymers, which are commercially available from Nafion. TM (Cholmous Company), Aquivion (registered trademark) (Solvay Specialty Polymers), Flemion TM Asahi Glass Group and Aciplex TM (PFSA from Asahi Kasei Chemical Co., Ltd.), etc.

[0176] In the catalyst-coated electrolyte membrane of the present invention, the breaking point stress of the (B-1) ionomer is preferably 0.01 or more and 0.5 or less relative to the breaking point stress of the (A) electrolyte membrane. That is, for example, when the breaking point stress of the (A) electrolyte membrane is 85 MPa, it is preferably 0.85 MPa to 42.5 MPa. With the above configuration, especially in the AEMWE process where the state change from liquid to gaseous occurs continuously, sufficient mechanical strength to withstand use can be achieved.

[0177] The fracture point stress of the catalyst layer (B), relative to the fracture point stress of the electrolyte membrane (A), is preferably 0.05, more preferably 0.10, and particularly preferably 0.12. The upper limit is preferably 0.35, more preferably 0.24, and particularly preferably 0.20. Therefore, the most preferred value for the fracture point stress of the catalyst layer (B), relative to the fracture point stress of the electrolyte membrane (A), is 0.12 or more and 0.20 or less.

[0178] In this specification, the fracture point stress of the ionomer described above (B-1) refers to the value obtained by the same measurement method as that used for the electrolyte membrane described above (A). That is, it is not measured under actual use conditions, but rather a test piece identical to that used for the electrolyte membrane in (A) is prepared, and a uniaxial tensile test is performed using an EZ-SX (manufactured by Shimadzu Corporation) at 25°C and 40%RH at 0.3 m / min, and the fracture point stress is calculated based on the cross-sectional area of ​​the fracture surface.

[0179] The preferred method for achieving the above-mentioned fracture point stress is to use a polymer that is the same as or similar to the polymer with ion exchange groups used in the electrolyte membrane (A) for the ionomer (B-1). That is, the ionomer (B-1) is preferably selected from polymers having the structural units shown in the above formula (1).

[0180] It is particularly preferred to use the same polymer with ion-exchange groups as the polymer used in the electrolyte membrane (A).

[0181] As a component of the (B) catalyst layer in this invention, the amount of (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. This upper limit is more preferably 1.2, 1.0, 0.7, and 0.5, respectively. Furthermore, the lower limit is more preferably 0.1, 0.15, and 0.2. Therefore, the amount of (B-1) ionomer in the (B) catalyst layer is most preferably 0.2 or more and 0.5 or less.

[0182] [Fabrication of catalyst-coated electrolyte membranes]

[0183] The catalyst-coated electrolyte membrane of the present invention is obtained by forming a catalyst layer (B) on at least one side, more preferably both sides, of the electrolyte membrane (A). Methods for forming the catalyst layer (B) include pulse spraying, ultrasonic spraying, mold coating, rod coating, electrode transfer, and other coating methods. Depending on the coating method, a drying step may be included.

[0184] A preferred example of the catalyst-coated electrolyte membrane of the present invention is a catalyst-coated electrolyte membrane having anion-exchange water electrolysis performance. Figure 2 A schematic cross-sectional view of an example of a catalyst-coated electrolyte membrane with anion-exchange water electrolysis performance is shown. Figure 2 The catalyst-coated electrolyte membrane 101 has an electrolyte membrane 11 (A), which is formed by impregnating a polymer (electrolyte polymer) 1 having ion exchange groups into the pores of a substrate membrane 2, which is a porous substrate. The electrolyte membrane 11 has a first catalyst layer 12 on its first main surface containing an ionomer 3 (B-1) and a hydrogen evolution catalyst 4, and a second catalyst layer 13 on its second main surface containing an ionomer 3 (B-1) and an oxygen evolution catalyst 5.

[0185] The performance of anion-exchange membrane-type water electrolysis refers to the following: A catalyst layer containing hydrogen evolution-capable metal powder dispersed in an ionomer is formed on the cathode side of an electrolyte membrane with anion exchange groups, and a catalyst layer containing oxygen evolution-capable metal powder dispersed in an ionomer is formed on the anode side, thus forming an electrochemical unit. When an alkaline solution is passed through this electrochemical unit, and current is applied to the electrochemical unit containing the electrolyte membrane (which undergoes ion exchange to form OH ions) and the ionomer, water electrolysis can be performed without a significant voltage increase. Specifically, the hydrogen evolution catalyst typically uses platinum-supported carbon or platinum-ruthenium alloy-supported carbon, while the oxygen evolution catalyst typically uses iridium oxide. As long as 1 mol / L potassium hydroxide is used in the alkaline solution, and the electrochemical unit is at a temperature of 80°C and a current density of 1 A / cm², water electrolysis can be achieved. 2 When electrolysis is performed, the electrolysis voltage can be below 2.0V, preferably 1.7V to 1.8V, and particularly preferably below 1.78V.

[0186] Ion exchange capacity refers to the amount of ions that an ion exchange resin can adsorb; a higher value indicates higher ion conductivity. In the electrolyte membrane of the present invention (A), the ion exchange resin is a polymer with ion exchange groups. Higher ion exchange capacity results in higher ion conductivity, but also higher water content, causing the electrolyte membrane to swell and reducing 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.

[0187] The catalyst-coated electrolyte membrane of the present invention is suitable for fuel cells and electrolysis devices.

[0188] Example 1

[0189] The present invention will be further described below with reference to specific embodiments. The present invention is not limited to these descriptions and may be appropriately modified without departing from its spirit.

[0190] [Synthesis of compound (1-1)]

[0191] In a four-necked flask, tetrabutylammonium chloride (3.04 g), 1,10-dichlorodecane (1097 mmol), and 2,7-dibromofluorene (109.7 mmol) were added to a two-necked flask in a 200 g aqueous solution of sodium hydroxide (600 mL) using a syringe, and stirred under a nitrogen atmosphere. The reaction mixture was then reacted at 90 °C for 90 min under a nitrogen atmosphere, and the resulting reaction solution was cooled to room temperature (25 °C). The organic phase in the cooled reaction solution was extracted with toluene (200 mL) using a separatory funnel, and washed with 1 M hydrochloric acid (50 mL) and saturated brine (200 mL × 2). Toluene was removed from the resulting organic phase using an evaporator, and unreacted 1,10-dichlorodecane was removed under reduced pressure at 180 °C. The resulting residue was passed through a silica gel column (expansion solvent: hexane) to give compound (1-1) (68.7 mmol).

[0192] [Compound (1-1)]

[0193]

[0194] [Synthesis of compounds (1-2)]

[0195] Compound (1-1) (57.7 mmol) and 1,3,5-trimethylbenzene (159 mL) were added to a separable flask and stirred while bubbling (20 mL / min) under a nitrogen atmosphere for 30 minutes. Next, cesium carbonate (173 mmol), pentyl acid (57.7 mmol), tris(2-methoxyphenyl)phosphine (407 mg), Pd2(dba)3 (291 mg), and 1,2,4,5-tetrafluorobenzene (57.7 mmol) were added and stirred. These mixtures were reacted at room temperature (25 °C) under a nitrogen atmosphere for 15 minutes, then at 98 °C for 8 hours, and finally at 75 °C for 75 minutes.

[0196] 1M hydrochloric acid (100 mL) and toluene (600 mL) were added to the obtained reactants (solid component). After stirring at 60 °C for 30 minutes, the insoluble components were 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 brine, and the liquid components were removed by evaporation, allowing it to dry and solidify. The resulting residue was dissolved in toluene and reprecipitated in a hexane / methanol ratio of 3 / 1. The precipitate was filtered to remove the liquid components. The resulting solid component was dried under vacuum to obtain compounds (1-2) with a molecular weight distribution of 4.88. Figure 2 The GPC results shown indicate that the peak endpoint for compounds (1-2) was at 14.025 minutes, confirming the reduction of low molecular weight components.

[0197] [Compounds (1-2)]

[0198]

[0199] [Synthesis of compounds (1-3)]

[0200] Compound (1-2) (2.07 g) was dissolved in 3-methoxy-N,N-dimethylpropionamide (25 mL). A 25% (w / w) trimethylamine methanol solution (10 mL) was added to the resulting solution, and the mixture was stirred at 100 °C for 9 hours. The solution was then cooled to room temperature (25 °C), and the solution was reprecipitated in toluene. The precipitate was filtered to remove the liquid components. The resulting solid component was dried under vacuum to obtain compound (1-3) (2.29 g). Since compound (1-2) was synthesized by reducing the low molecular weight components, as previously described, it is presumed that compound (1-3) is also a compound with a low molecular weight component.

[0201] [Compounds (1-3)]

[0202]

[0203] [Electrolyte membrane 1]

[0204] As a porous substrate, polyethylene (Hipore NH815: manufactured by Asahi Kasei) with submicron-sized pores was heated, and a solution of the above compounds (1-3) dissolved in a solvent was added dropwise into it. The solvent was dried at 80°C, and the compounds were filled into the pores to obtain an electrolyte membrane 1 with a diameter of 13 μm.

[0205] <Determination of the fracture point stress of the electrolyte membrane>

[0206] The electrolyte membrane 1 was cut into 1.5mm × 50mm pieces and subjected to a uniaxial tensile test at 0.3m / min using an EZ-SX (manufactured by Shimadzu Corporation) at 25°C and 40%RH. The stress at the fracture point was calculated based on the cross-sectional area of ​​the fracture surface. The results are shown in Table 1.

[0207] [Electrolyte membrane 2-4]

[0208] As electrolyte membranes 2–4, the fracture point stress of Fumasep FAAM-20 (manufactured by Fumatech), CMX-40-10 (manufactured by ORION Polymer), and PiperION-A20-HCO3 (manufactured by Versogen) was measured using the same method as described above. The results are shown in Table 1.

[0209] [Table 1]

[0210]

[0211] [(B-1) Determination of the fracture point stress of ionomers]

[0212] A glass plate was heated, and a solution of compounds (1-3) dissolved in a solvent (a mixture of dimethyl sulfoxide and hexanol) was added dropwise. The solvent was dried at 80°C, and the ionomer film was peeled off from the glass plate to prepare a 28 μm test piece. The resulting ionomer film was cut into 3.0 mm × 50 mm pieces and subjected to uniaxial tensile tests at 0.3 m / min using an EZ-SX (manufactured by Shimadzu Corporation) at 25°C and 40% RH. The stress at the fracture point was calculated based on the cross-sectional area of ​​the fracture surface. The results are shown in Table 2.

[0213] [Table 2]

[0214]

[0215] <Ion exchange capacity test>

[0216] Using 50 mg each of electrolyte membranes 1-4, immerse them in a 1 mol / L sodium nitrate aqueous solution and place them at 25°C for 24 hours to allow sufficient ion exchange between chloride and nitrate ions in the electrolyte membrane. Then, perform potentiometric titration with a 0.02 mol / L silver nitrate aqueous solution. Calculate the ion exchange capacity based on the titration amount to the inflection point and the weight of the electrolyte membrane.

[0217] For electrolyte membranes 2-4, in order to perform anion exchange, they were pre-immersed in an aqueous sodium chloride solution for 48 hours, and then potentiometric titration was performed using the method described above. The titration was conducted using a COM-A19 titrator manufactured by HIRANUMA.

[0218] For electrolyte membrane 1, different porous substrates with membrane thicknesses of 15μm, 9μm, and 25μm were prepared and coated with a solution containing polymer components. The volume of the solution was 1.1 times the pore volume calculated based on the porosity and thickness of each porous substrate. Electrolyte membranes 1 with different membrane thicknesses were made and the same experiment was conducted.

[0219] The calculation method is shown in Calculation Method 1, and the results are shown in Table 3.

[0220] [Calculation Method 1]

[0221] Exchange capacity (mmol / g) = (EP1 - BL1) × TF × C1 × K1 / S

[0222] EP1: Titration volume (mL) required to reach the first endpoint

[0223] BL1: Titration amount (mL) required for blank test

[0224] TF: Titration coefficient (1.0003)

[0225] C1: Concentration conversion factor (0.0001 mol / mL)

[0226] K1: Unit conversion factor (1000)

[0227] S: Sample collection volume (g)

[0228] [Table 3]

[0229]

[0230] [Example 1: Catalyst-coated electrolyte membrane 1]

[0231] In a solution prepared by dissolving the compound shown in (1-3) in a solvent (a mixture of isopropanol and water), carbon (TEC66E50: Tanaka Precious Metals) supporting platinum and ruthenium was dispersed to obtain metal dispersion ionomer solution 1.

[0232] Alternatively, instead of carbon supporting platinum and ruthenium, iridium oxide (Premion: made by THERMO SCIENTIFIC CHEMICALS) was used to obtain ionomer solution 2 by the same method.

[0233] The ionomer solution 1 is coated onto the electrolyte membrane 1 by spraying and dried at 80°C. Then, the ionomer solution 2 is coated onto the opposite side by spraying and dried at 80°C to obtain the catalyst-coated electrolyte membrane 1 of the present invention (catalyst area 1cm×1cm).

[0234] The thickness of the coated catalyst was adjusted by spraying a metal-dispersed ionomer solution 1 with an ionomer / carbon ratio of 0.5, while simultaneously using fluorescence X-ray diffraction to quantitatively adjust the thickness so that the platinum content per unit area of ​​the coated catalyst was 0.5 mg / cm². 2 Similarly, a metal-dispersed ionomer solution 2 with an ionomer / iridium ratio adjusted to 0.29 was sprayed, and the thickness was adjusted while being quantitatively analyzed using fluorescent X-rays to ensure that the iridium content per unit area in the coated catalyst was 1.5 mg / cm². 2.

[0235] Comparative Example 1: Catalyst-coated electrolyte membrane 2

[0236] Comparative Example 1 (catalyst-coated electrolyte membrane 2) was obtained in the same manner as Example 1, except that the electrolyte membrane 1 was replaced with electrolyte membrane 2.

[0237] <Anion Exchange Membrane Water Electrolysis Experiment>

[0238] In Examples 1 and 1 (Comparative Example 1), a nickel porous body was disposed on the anode side of the catalyst-coated electrolyte membrane, and carbon paper was disposed on the cathode side as a porous transport layer (PTL). Anion exchange membrane water electrolysis experiments were conducted using JARI standard units at 80°C and with a flow rate of 1 cc / min on the anode side and 0 cc / min on the cathode side of a 1M potassium hydroxide aqueous solution. (1 A / cm) 2 The measurement results are shown in Table 4. This voltage value was calculated by averaging 60 data points from 2 minutes 1 second to 3 minutes 0 seconds, measured once every 1 second for 3 minutes.

[0239] [Table 4]

[0240]

[0241] <Alkali Resistance Test>

[0242] An immersion test was conducted for 400 hours in a 1M potassium hydroxide aqueous solution, similar to the anion exchange membrane water electrolysis test described above, and the unit resistance at 1.5V was measured. The rate of change from the initial stage was calculated. The results are shown in Table 5.

[0243] [Table 5]

[0244]

[0245] The test results of Example 1 confirm that the catalyst-coated electrolyte membrane of the present invention exhibits low voltage and excellent water electrolysis performance in the anion exchange membrane water electrolysis test. Furthermore, it shows a small rate of change in unit resistance in the alkali resistance test, indicating excellent alkali resistance.

[0246] Industrial practicality

[0247] According to the present invention, it is possible to provide a catalyst-coated electrolyte membrane with sufficiently high durability, even for use in the AEMWE process.

[0248] This application claims priority to Japanese Patent Application No. 2023-194981, filed on November 16, 2023, the entire contents of which are incorporated herein by reference.

[0249] Explanation of reference numerals in the attached figures

[0250] 1: Polymers with ion exchange groups (electrolyte polymers);

[0251] 2: Substrate film;

[0252] 3: Isopolymers;

[0253] 4: Hydrogen evolution catalyst;

[0254] 5: Oxygen evolution catalyst;

[0255] 11: Electrolyte membrane;

[0256] 12: First catalyst layer;

[0257] 13: Second catalyst layer;

[0258] 100: Catalyst-coated electrolyte membrane.

Claims

1. A catalyst-coated electrolyte membrane, comprising: (A) An electrolyte membrane with a fracture stress of 85 MPa or higher; and (B) Catalyst layer.

2. The catalyst-coated electrolyte membrane according to claim 1, wherein, The electrolyte membrane (A) comprises a polymer having anion exchange groups.

3. The catalyst-coated electrolyte membrane according to claim 1 or 2 has anion exchange membrane 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 0.8–1.5 mmol / g.

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

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

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

9. The catalyst-coated electrolyte membrane according to claim 1 or 2, wherein, The electrolyte membrane (A) contains a polymer having structural units represented by the following formula (1). In the formula, Ar 1 It is an aromatic group with an ion-exchange group, or a group consisting of an aromatic ring with an ion-exchange group linked by a single bond, and multiple Ar groups. 1 They can be the same or different. Ar 2 An aromatic group without an ion-exchange group, or a group consisting of two or more aromatic rings connected by single bonds or spirochetes without an ion-exchange group, and multiple Ar atoms. 2 They can be the same or different. Ar 1 The aromatic ring it possesses is similar to Ar 2 The aromatic rings it possesses are connected by single bonds.

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