Ion exchange membrane, membrane electrode assembly, cell for redox flow battery, and redox flow battery

Abstract

An ion exchange membrane comprising a resin composition that contains a cation exchange resin and a side chain heteroaromatic resin having a structural unit represented by general formula 1 (in the formula, R1, R2, and R3 may be the same or different from each other, and each represent a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1-10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6-10 carbon atoms, R4 represents a direct bond, a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1-10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6-10 carbon atoms, and Hc represents a substituted or unsubstituted heteroaromatic group having 4-30 carbon atoms, having at least one nitrogen atom in the heteroaromatic ring structure, and including a 5-membered ring and / or 6-membered ring structure.).

Description

[Technical Field]

[0001] The present invention relates to an ion exchange membrane, a membrane electrode assembly, a cell for a redox flow battery, and a redox flow battery. [Background technology]

[0002] Redox flow batteries are secondary batteries that store and discharge electricity, and are suitable for large, stationary batteries used to level out electricity consumption. A redox flow battery has a structure in which a positive electrode and a positive electrode electrolyte (positive electrode cell) containing a positive electrode redox active material, and a negative electrode and a negative electrode electrolyte (negative electrode cell) containing a negative electrode redox active material are separated by a diaphragm, and charging and discharging are performed using the oxidation-reduction reaction of both redox active materials. By circulating the electrolyte containing both redox active materials from a storage tank to an electrolytic cell, it is possible to increase the capacity.

[0003] Examples of redox active materials used in electrolytes include iron / chromium-based, chromium / bromine-based, zinc / bromine-based, and vanadium-based systems that utilize differences in electric charge. In particular, vanadium-based redox flow batteries have advantages such as high electromotive force, rapid electrode reaction of vanadium ions, low hydrogen generation as a side reaction, and high output, so their development is being pursued in earnest.

[0004] In vanadium-based redox flow batteries, the divalent (V) of vanadium in the negative electrode cell 2+ ) / 3 valent (V 3+ ) and the tetravalent (V) of vanadium in the positive electrode cell 4+ ) / 5-valent (V 5+This utilizes the oxidation-reduction reaction. Thus, because the redox active material contained in the electrolyte of the positive electrode cell and the negative electrode cell is the same type of vanadium ion, even if the electrolyte is mixed through the diaphragm, it can be regenerated by an electrical process, which is advantageous in that it can be used for a long period of time. However, when the redox active material permeates, the stored charge is neutralized and the current efficiency decreases, so it is desirable to suppress the permeation of the redox active material as much as possible in the diaphragm. On the other hand, protons contained in the electrolyte can easily permeate the diaphragm, which reduces the resistance of the battery and increases the voltage efficiency, so it is desirable to not hinder the permeation of protons as much as possible in the diaphragm. In other words, a diaphragm that can achieve both high current efficiency and high voltage efficiency, that is, high power efficiency (power efficiency is the product of current efficiency and voltage efficiency), is required.

[0005] It has been disclosed that the ion exchange membrane is processed to suppress the permeation of redox active material and achieve high power efficiency (Patent Documents 1-3). Patent Document 1 discloses that by alternately stacking cation exchange layers and anion exchange layers, excellent initial power efficiency can be achieved. Patent Document 2 discloses that by using a film containing a sulfonated polymer and a heterocyclic molecule containing multiple nitrogen atoms, the proton area resistivity is low and the vanadium ion permeability selectivity is excellent. Patent Document 3 discloses that by using a polymer electrolyte membrane equipped with a crossover prevention layer, which is a metal layer formed by reducing a cationic metal, it is possible to achieve superiority in at least one of the following: discharge capacity, current efficiency, voltage efficiency, and power efficiency. Patent Document 4 discloses that by using a diaphragm for a redox flow battery comprising a first ion exchange resin layer, an anion exchange resin layer containing an anion exchange compound, and a second ion exchange resin layer in this order, curling is suppressed and power efficiency is excellent.

[0006] Patent Document 5 discloses a 5% by mass solution obtained by dissolving a fluororesin having an acidic group in a solvent in which the mass ratio of ethanol to water is 50:50. Patent Document 6 discloses that a thin film with high strength, good adhesion to a substrate, and good chemical resistance can be obtained by using a polymer electrolyte solution obtained by dissolving a fluororesin having an acidic group in a solvent containing a hydrophilic, high-boiling-point polar solvent. Patent Document 7 and Non-Patent Document 1 show that when attempting to produce a polymer with a high proportion of sulfonic acid groups in a fluororesin having a specific acidic group, it is difficult to sufficiently increase the molecular weight of the polymer and to produce a polymer electrolyte membrane with sufficient mechanical strength. Patent Document 8 discloses that by co-extruding a perfluorosulfonic acid polymer precursor with an incompatible polymer, a multilayer film having a perfluorosulfonic acid polymer precursor layer with reduced thickness supported by an incompatible polymer layer can be formed, and a proton exchange film with reduced thickness can be obtained. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-260390 [Patent Document 2] International Patent Application Publication No. 2017 / 155648 [Patent Document 3] International Patent Application Publication No. 2016 / 163773 [Patent Document 4] International Patent Application Publication No. 2021 / 215126 [Patent Document 5] Japanese Patent Application Publication No. 07-296634 [Patent Document 6] Japanese Patent Publication No. 2004-164854 [Patent Document 7] International Patent Application Publication No. 2008 / 090990 [Patent Document 8] International Patent Application Publication No. 2013 / 091073 [Non-patent literature]

[0008] [Non-Patent Document 1] W. Vielstich, HAGasteiger, A. Lamm (eds.), "Handbook of Fuel Cells, vol. 3," John Wiley & Sons, Ltd., USA, 2003, Chapter 30, pp. 351-352. [Overview of the project]

[0009] Embodiments of the present invention are as follows. <1> A side-chain heteroaromatic resin having a structural unit represented by the following general formula 1, and [ka] (In the formula, R 1 , R 2 , and R 3 These may be the same or different, and are a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 This is a directly bonded, substituted, or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Hc is a heteroaromatic group having 4 to 30 carbon atoms, containing at least one substituted or unsubstituted nitrogen atom within a heteroaromatic ring structure, and including 5-membered and / or 6-membered ring structures. Cation-exchangeable resin, An ion exchange membrane comprising a resin composition containing the following. <2> The weight ratio of the side-chain heteroaromatic resin to the cation-exchangeable resin is 1:100 to 100:1. <1> The ion exchange membrane described above. <3> The cation exchange resin is a fluororesin. The ion exchange membrane according to <1> or <2>. <4> The fluororesin has a structural unit represented by the following general formula G1. [Chemical formula] (In the formula, X 5 , X 6 , X 7 , and X 8 may be the same or different from each other, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms. The halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. X 5 and X 6 , or X 5 and X 7 may be bonded to each other to form a cyclic structure. R 5 , and R 6 may be the same or different from each other, and is a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms. The halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. X 9 is a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ. Z is at least one selected from the group consisting of a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, and amines. Fluororesins may be crosslinked with each other through X 9 by ionic crosslinking. h and p represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ h < 1, 0 < p ≦ 1, and h + p = 1. i is an integer from 0 to 8. j is 0 or 1. k, l, and m may be the same or different, and are integers between 0 and 6, except when k, l, and m are all 0. 9 CF(CF2X 10 )2, X 10 (This refers to a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, where Z is the same as above.) <3> The ion exchange membrane described above. <5> A layer (L) containing the aforementioned resin composition, Having a structural unit represented by the following general formula G1, [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) A layer (M) containing a fluororesin and a layer (M) are alternately formed, <1> ~ <4> An ion exchange membrane as described in any of the following. <6> The system has one layer each of the aforementioned layer (L) and the aforementioned layer (M). <5> The ion exchange membrane described above. <7> The layer (L), the layer (M), and the layer (L) are arranged in this order. <5> or <6> The ion exchange membrane described above. <8> The resin includes a side-chain heteroaromatic resin having a structural unit represented by the following general formula 2, [ka] (In the formula, R 1 , R 2 , and R 3 These may be the same or different, and are a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 This is a directly bonded, substituted, or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Hc is a heteroaromatic group having 4 to 30 carbon atoms, containing at least one substituted or unsubstituted nitrogen atom within a heteroaromatic ring structure, and including 5-membered ring and / or 6-membered ring structures. Rf is an aliphatic hydrocarbon group substituted with at least one fluorine atom. X - (This is a counter-anion.) Ion exchange membrane. <9> A layer (L) containing the aforementioned side-chain heteroaromatic resin, Having a structural unit represented by the following general formula G1, [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) A layer (M) containing a fluororesin and a layer (M) are alternately formed, <8> The ion exchange membrane described above. <10> The system has one layer each of the aforementioned layer (L) and the aforementioned layer (M). <9> The ion exchange membrane described above. <11> The layer (L), the layer (M), and the layer (L) are arranged in this order. <9> The ion exchange membrane described above. <12> The aforementioned layer (L) further comprises a cation exchange resin. <9> ~ <11> An ion exchange membrane as described in any of the following. <13> The weight ratio of the side-chain heteroaromatic resin to the cation-exchangeable resin is 1:100 to 100:1. <12> The ion exchange membrane described above. <14> The cation exchange resin is a fluororesin. <12> or <13> The ion exchange membrane described above. <15> The fluororesin has a structural unit represented by the following general formula G1, [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) <14> The ion exchange membrane described above. <16> The aforementioned side-chain heteroaromatic resin further comprises a structural unit represented by the following general formula 2: [ka] (In the formula, R 1 , R 2 , and R 3 These may be the same or different, and are a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 This is a directly bonded, substituted, or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Hc is a heteroaromatic group having 4 to 30 carbon atoms, containing at least one substituted or unsubstituted nitrogen atom within a heteroaromatic ring structure, and including 5-membered ring and / or 6-membered ring structures. Rf is an aliphatic hydrocarbon group substituted with at least one fluorine atom. X - (This is a counter-anion.) <1> The ion exchange membrane described above. <17> The molar ratio of the structural unit represented by the general formula 1 to the structural unit represented by the general formula 2 is 1:100 to 100:1. <16> The ion exchange membrane described. <18> The weight ratio of the side-chain heteroaromatic resin to the cation-exchangeable resin is 1:100 to 100:1. <16> or <17> The ion exchange membrane described above. <19> The cation exchange resin is a fluororesin. <16> ~ <18> An ion exchange membrane as described in any of the following. <20> The fluororesin has a structural unit represented by the following general formula G1, [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) <16> ~ <19> An ion exchange membrane as described in any of the following. <21> A layer (L) containing the aforementioned resin composition, Having a structural unit represented by the following general formula G1, [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) A layer (M) containing a fluororesin and a layer (M) are alternately formed, <20> The ion exchange membrane described above. <22> The system has one layer each of the aforementioned layer (L) and the aforementioned layer (M). <21> The ion exchange membrane described above. <23> The layer (L), the layer (M), and the layer (L) are arranged in this order. <21> The ion exchange membrane described above. <24> A layer (L1) containing a heteroaromatic structure-containing fluororesin having a structural unit represented by the following general formula A1, its saponide, or its salt, [ka] (In the formula, X 1 , X 2 , X 3 , and X 4 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 1 and X 2 , or X 1 and X 3 These may be bonded to each other to form a ring structure. R 1 , R 2may be the same or different and is a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, R 3 is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, R 4 is a linking group between NR 3 and Hc, and is a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms, X 10 is a divalent group represented by the formula -CO2- or -SO2-, Hc is a substituted or unsubstituted heteroaromatic group having 4 to 30 carbon atoms, containing at least one nitrogen atom and including a 5-membered ring and / or a 6-membered ring structure, a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1, b is an integer from 0 to 8, c is 0 or 1, d, e, and f may be the same or different and are integers from 0 to 6. However, d, e, and f are not simultaneously 0.) a layer (M1) containing a fluororesin (G1) having a structural unit represented by the following general formula G1, and an ion exchange membrane having

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0010] [Figure 1] Figure 1 shows an example of a schematic diagram of a redox flow battery using a diaphragm for a redox flow battery in this embodiment. [Modes for carrying out the invention]

[0011] The following describes in detail an embodiment for carrying out the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist.

[0012] [First Embodiment] First, the first embodiment will be described.

[0013] Patent Document 1 discloses the use of an aromatic polysulfone polymer as an anion exchange base layer to improve current efficiency and power efficiency. However, it has been shown that while current efficiency is excellent, cell resistance increases and voltage efficiency decreases. Therefore, there is a need for an anion exchange base layer that offers a good balance of current efficiency, voltage efficiency, and current efficiency. Patent Document 2 discloses Nafion® 117, which is produced by reacting several heterocyclic molecules to improve vanadium ion permeability selectivity while suppressing an increase in proton surface resistance. However, lowering the proton surface resistance leads to lower vanadium ion permeability selectivity, while increasing the vanadium ion permeability selectivity leads to higher proton surface resistance, and achieving both simultaneously remains a challenge. Furthermore, the examples were not evaluated as redox flow batteries, so the current efficiency, voltage efficiency, and power efficiency are unknown. However, since the proton surface resistance in the examples is higher than that of Nafion® 117, it can be inferred that the voltage efficiency is lower than that of Nafion® 117. For these reasons, there is a need for a material that offers a good balance of current efficiency, voltage efficiency, and power efficiency. Patent Document 3 discloses a crossover prevention layer, which is a metal layer formed by reducing a cationic metal inside a polymer electrolyte membrane, in order to improve at least one of the characteristics of discharge capacity, current efficiency, voltage efficiency, and power efficiency. However, there is a need for even higher characteristics. Patent Document 4 discloses the use of several polymer compounds as an anion-exchangeable resin layer to achieve high power efficiency. However, it has been shown that when an anion-exchangeable resin layer is not located between the ion-exchangeable resin layer and the anion-exchangeable resin layer, high power efficiency may be obtained as an initial characteristic, but high power efficiency cannot be obtained after 100 cycles. For this reason, there is a need for the anion-exchangeable compound contained in the anion-exchangeable resin layer used in Patent Document 4 to have even higher properties.

[0014] The object of the present invention is a side-chain heteroaromatic resin, resin composition, ion exchange membrane, membrane electrode assembly, redox flow battery cell using these, and redox flow battery, which can be obtained from a redox battery cell that has a good balance of current efficiency and voltage efficiency and high power efficiency.

[0015] As a result of diligent research into the above-mentioned problems, the inventors have found that by using a side-chain heteroaromatic resin having a specific structural unit as a diaphragm for a redox flow battery cell, a well-balanced and excellent current efficiency and voltage efficiency, as well as high power efficiency, can be obtained.

[0016] The ion exchange membrane according to the first embodiment comprises the following resin composition. That is, the resin composition is A side-chain heteroaromatic resin having a structural unit represented by the following general formula 1, and [ka] (In the formula, R 1 , R 2 , and R 3 These may be the same or different, and are a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 This is a directly bonded, substituted, or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Hc is a heteroaromatic group having 4 to 30 carbon atoms, containing at least one substituted or unsubstituted nitrogen atom within a heteroaromatic ring structure, and including 5-membered and / or 6-membered ring structures. Cation-exchangeable resin, Includes. According to this embodiment, it is possible to provide a side-chain heteroaromatic resin having a novel specific structural unit. Furthermore, according to this embodiment, it is possible to provide a side-chain heteroaromatic resin, resin composition, ion exchange membrane, membrane electrode assembly, redox flow battery cell using these, and redox flow battery, which can be obtained from a redox flow battery cell that has excellent balance between current efficiency and voltage efficiency and exhibits high power efficiency.

[0017] Furthermore, the ion exchange membrane according to the first embodiment includes a side-chain heteroaromatic resin having a structural unit represented by the following general formula 2. [Chemical formula] (In the formula, R 1 R 2 and R 3 may be the same or different and are each a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 is a direct bond, a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Hc is a substituted or unsubstituted heteroaromatic group having at least one nitrogen atom in the heteroaromatic ring structure, containing a 5-membered ring and / or a 6-membered ring structure, and having 4 to 30 carbon atoms. Rf is an aliphatic hydrocarbon group substituted with at least one fluorine atom X - is a counter anion.)

[0018] <Side-chain heteroaromatic resin> The side-chain heteroaromatic resin in the first embodiment has a structural unit represented by the following general formula 1. [Chemical formula] (In the formula, R 1 R 2 and R 3 may be the same or different and are each a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 is a direct bond, a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Hc is a substituted or unsubstituted heteroaromatic group having at least one nitrogen atom in the heteroaromatic ring structure and containing a 5-membered ring and / or a 6-membered ring structure, and having 4 to 30 carbon atoms.)

[0019] R in the general formula (1) above 1 , R 2 , and R 3 may be the same or different and each is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0020] In the case of a substituted aliphatic hydrocarbon group or a substituted aromatic hydrocarbon group, the substituent is not particularly limited. For example, a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, a nitrile group (-CN), an alkoxy group (-OR a ), an alkyl carbonate group (-OCO2R a ), an alkyl ester group (-CO2R a ), an acyl group (-COR a ), a sulfide group (-SR a ), a sulfoxide group (-SOR a ), a sulfone group (-SO2R a ), and a urethane group (-NHCO2R a ) etc. may be mentioned. R a is an aliphatic hydrocarbon group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms. In the case of an aliphatic hydrocarbon group, the substituent may be an aromatic hydrocarbon group having 6 to 10 carbon atoms, and in the case of an aromatic hydrocarbon group, the substituent may be an aliphatic hydrocarbon group having 1 to 10 carbon atoms. When having a substituent, the substituent may be a single kind or a plurality of kinds.

[0021] R 1 , R 2 , and R 3 are preferably a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, and more preferably a hydrogen atom, an unsubstituted aliphatic hydrocarbon group, because the raw material compound for producing the side-chain heteroaromatic resin is easily available. Further preferably, it is a hydrogen atom, because the raw material compound for producing the side-chain heteroaromatic resin has high reactivity and tends to suppress the production cost.

[0022] The number of carbon atoms in the substituted or unsubstituted aliphatic hydrocarbon group is 1 to 10. Since the raw material compounds for producing side-chain heteroaromatic resins are readily available, the number of carbon atoms is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 or 2, and even more preferably 1.

[0023] The number of carbon atoms in the substituted or unsubstituted aromatic hydrocarbon group is 6 to 10. Since the raw material compounds for producing side-chain heteroaromatic resins are readily available, the number of carbon atoms is preferably 6 to 10, more preferably 6 to 8, and even more preferably 6.

[0024] R in the above general formula 1 4 This is a directly bonded, substituted, or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. The substituents here are the same as those described above.

[0025] Here, a direct bond refers to the relationship between Hc and R in the structural unit represented by general formula 1. 3 This refers to a direct bond between the carbon atoms that make up the main chain and the R. 4 In descriptions relating to this, the same meaning is indicated.

[0026] The number of carbon atoms in the substituted or unsubstituted divalent aliphatic hydrocarbon group is 1 to 10. Since the raw material compounds for producing side-chain heteroaromatic resins are readily available, the number of carbon atoms is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 or 2, and even more preferably 1.

[0027] The number of carbon atoms in the substituted or unsubstituted divalent aromatic hydrocarbon group is 6 to 10. Since the raw material compounds for producing side-chain heteroaromatic resins are readily available, the number of carbon atoms is preferably 6 to 10, more preferably 6 to 8, and even more preferably 6.

[0028] R in the above general formula 1 4As such, directly bonded, or substituted or unsubstituted aliphatic hydrocarbon groups are preferred because the raw material compounds for producing side-chain heteroaromatic resins are readily available, and directly bonded or unsubstituted aliphatic hydrocarbon groups are more preferred. Direct bonding is even more preferred because it tends to increase the reactivity of the raw material compounds for producing side-chain heteroaromatic resins and reduce manufacturing costs. 4 However, in the case of direct bonding, the structural unit represented by general formula 1 is represented by general formula 1-2 below. The substituents here are the same as those described above. [ka] (In the formula, the definition of each substituent is the same as that of General Formula 1 described above.)

[0029] In the above general formula 1, Hc is a heteroaromatic group having 4 to 30 carbon atoms, having at least one nitrogen atom in a heteroaromatic ring structure, and including a 5-membered ring and / or a 6-membered ring structure, whether substituted or unsubstituted.

[0030] The five-membered ring and / or six-membered ring structure in Hc of the above general formula 1 is not particularly limited, but examples include imidazole structure, benzimidazole structure, imidazopyridine structure, pyridine structure, oxazole structure, thiazole structure, pyridazine structure, pyrimidine structure, sinnoline structure, quinazoline structure, phthalazine structure, quinoxaline structure, pteridine structure, purine structure, 2,2'-bipyridyl structure, 2,3'-bipyridyl structure, 2,4'-bipyridyl structure, 1,7-phenanthroline structure, 1,10-phenanthroline structure, 2,2':6',2''-terpyridine structure, etc. The Hc structures exemplified above may be a single structure or may consist of multiple structures.

[0031] Since Hc has at least one nitrogen atom in its heteroaromatic ring structure, among the above-mentioned 5-membered ring and / or 6-membered ring structures, it is preferable to have an imidazole structure, benzimidazole structure, imidazopyridine structure, pyridine structure, oxazole structure, thiazole structure, 2,2'-bipyridyl structure, 2,3'-bipyridyl structure, 2,4'-bipyridyl structure, 1,7-phenanthroline structure, or 1,10-phenanthroline structure, and among the imidazole structure, benzimidazole structure It is more preferable to have an imidazopyridine structure, a pyridine structure, an oxazole structure, a thiazole structure, a 2,2'-bipyridyl structure, or a 1,10-phenanthroline structure. When side-chain heteroaromatic resins are used in cells for redox flow batteries, durability tends to improve, so it is even more preferable to have an imidazole structure, a benzimidazole structure, an imidazopyridine structure, or a pyridine structure, and it is particularly preferable to have an imidazole structure or a pyridine structure.

[0032] H C The substituents in are the same as those described above.

[0033] Examples of Hc include imidazolyl group, benzimidazolyl group, imidazopyridinyl group, pyridinyl group, oxazonyl group, thiazolyl group, pyridadinyl group, pyrimidinyl group, synnolinyl group, quinazolinyl group, phthalazinyl group, quinoxalinyl group, pteridinyl group, prinyl group, 2,2'-bipyridinyl, 2,3'-bipyridinyl group, 2,4'-bipyridinyl group, 1,7-phenanthrolinyl group, 1,10-phenanthrolinyl group, and 2,2':6',2''-terpyridinyl group. Among these, imidazolyl group or pyridinyl group is preferred.

[0034] When Hc is an imidazolyl group, the structural unit represented by general formula 1 is the structural unit represented by general formulas 1-3 below. [ka]

[0035] When Hc is a pyridinyl group, the structural unit represented by general formula 1 is the structural unit represented by general formulas 1-4 below. [ka]

[0036] The structural unit represented by the above general formula 1 is preferably a structural unit represented by the following general formulas 1-5 or 1-6. [ka]

[0037] [ka]

[0038] The side-chain heteroaromatic resin preferably further has structural units represented by the following general formula 2. [ka] (In the formula, R 1 , R 2 , R 3 , R 4 Hc and n are defined the same as in General Formula 1, Rf is an aliphatic hydrocarbon group substituted with at least one fluorine atom. X - (This is a counter-anion.)

[0039] Side-chain heteroaromatic resins tend to have improved water resistance, chemical resistance, acid resistance, and alkali resistance by further possessing structural units represented by general formula 2.

[0040] The number of carbon atoms in the aliphatic hydrocarbon group in Rf is preferably 1 to 20, more preferably 3 to 16, even more preferably 3 to 11, and even more preferably 3 to 9.

[0041] The number of fluorine atoms substituted in the aliphatic hydrocarbon group in Rf is preferably 1 to 41, more preferably 3 to 25, and even more preferably 5 to 18.

[0042] Rf is given by the formula: -(CH2) o -(CF2) p It is preferable that the group is represented by -CF3 (wherein o+p is 1 to 19 and o is 0 to 19). o and p may be integers. o+p is preferably 1 to 19, more preferably 2 to 15, even more preferably 2 to 10, and even more preferably 2 to 8. From a similar viewpoint, o is preferably 0 to 19, more preferably 1 to 10, and even more preferably 2 to 4, and even more preferably 2, from the viewpoint of further improving the water resistance and chemical resistance of the side-chain heteroaromatic resin. From the viewpoint of easy availability of compounds that serve as precursors for Rf and the ability to suppress the manufacturing cost of the side-chain heteroaromatic resin, p is preferably 0 to 19, more preferably 2 to 10, even more preferably 3 to 7, and even more preferably 4 to 6.

[0043] More specifically, examples of Rf include -(CH2)2(CF2)3CF3, -(CH2)2(CF2)4CF3, and -(CH2)2(CF2)6CF3.

[0044] X - F - Cl - , Br - , I - HSO4 ― , (SO4 2- ) 1 / 2 NO3 ― , OH - These are some examples.

[0045] The structural unit represented by general formula 2 is preferably the structural unit represented by general formula 2-2 below. [ka]

[0046] The structural unit represented by general formula 2 is preferably a structural unit represented by general formula 2-3 or general formula 2-4 below. [ka]

[0047] [ka]

[0048] More preferably, structural units represented by general formula 2 include structures represented by general formula 2-5 or general formula 2-6 below. [ka]

[0049] [ka]

[0050] The side-chain heteroaromatic resin preferably has structural units represented by general formula 2, and more preferably has structural units represented by general formula 1 and structural units represented by general formula 2.

[0051] <Cation exchange resin> The resin composition in this embodiment preferably includes a cation exchange resin. A cation exchange resin is a resin that has the ability to exchange ions with cations (hereinafter also referred to as "positive ions").

[0052] The cation exchange resin is not particularly limited, but may be either a hydrocarbon resin or a fluororesin. For applications where cost reduction is required, hydrocarbon resins are preferred, while for applications where long-term durability is required, fluororesins are preferred. Hydrocarbon resins and fluororesins may be used individually or in combination.

[0053] Cation-exchange resins preferably contain functional groups having ion-exchange capacity. Examples of ion-exchange capacity functional groups are not particularly limited, but include sulfo groups (SO3H), carboxyl groups (CO2H), phenolic hydroxyl groups (OH), phosphate groups (PO3H2), thiol groups (SH), and alkali metal salts, alkaline earth metal salts, or transition metal salts of these functional groups. The ion-exchange capacity functional group may be a single type or a combination of multiple functional groups.

[0054] Among functional groups having ion exchange capacity, at least one selected from a sulfo group, a carboxyl group, and a phosphate group is preferred, more preferably at least one selected from a sulfo group and a carboxyl group, and particularly preferred is a sulfo group, as these tend to exhibit superior ion exchange capacity.

[0055] The hydrocarbon resin is not particularly limited, but examples include polystyrene, polyphenylene ether, polybenzimidazole, polyetheretherketone, polyimide, polyetherimide, polyaryletherketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylsulfone, etc., and is a resin having a functional group having the ion exchange ability described above. The hydrocarbon cation exchange resin may be crosslinked or copolymerized, and may have various substituents (for example, halogen atoms such as fluorine, chlorine, and bromine atoms; aliphatic hydrocarbon groups such as nitrile groups, methyl groups, ethyl groups, vinyl groups, allyl groups, 1-methylvinyl groups, n-propyl groups, iso-propyl groups, n-butyl groups, iso-butyl groups, sec-butyl groups, and tert-butyl groups; aromatic hydrocarbon groups such as benzyl groups, phenyl groups, and nitrile-substituted phenyl groups; amino groups; nitro groups; hydroxyl groups; silyl groups, etc.). The hydrocarbon resin may be used alone or in combination of multiple types.

[0056] The fluororesins are not particularly limited, but examples include partially fluorinated resins and fully fluorinated resins having the ion-exchange functional groups. Resins in which at least one hydrogen atom, though not all, of the hydrogen atoms on the carbon contained in the hydrocarbon-based cation-exchange resin is replaced with a fluorine atom, and resins in which all the hydrogen atoms on the carbon are replaced with fluorine, are exemplified as partially fluorinated resins and fully fluorinated resins.

[0057] The fluororesin is preferably a fluororesin (hereinafter also referred to as "fluororesin G1") having a structural unit represented by the following general formula G1. [ka] (In the formula, X 5 , X 6 , X 7 , and X 8 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 5 and X 6 , or X 5 and X 7 These may be bonded to each other to form a ring structure. R 5 , and R 6 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. X 9 is a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, where Z is at least one selected from the group consisting of hydrogen atoms, alkali metal atoms, alkaline earth metal atoms, and amines, and X 9 The fluororesins may be crosslinked by ionic crosslinking via the intermediary. h, and p represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ h < 1, 0 < p ≦ 1, and h + p = 1. i is an integer from 0 to 8. j is 0 or 1. k, l, and m may be the same or different from each other and are integers from 0 to 6. However, when k, l, and m are simultaneously 0, X 9 is CF(CF2X 10 )2, and X 10 is a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, and Z is the same as described above.)

[0058] X 5 X 6 X 7 and X 8 may be the same or different from each other and are a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms. The halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. X 5 and X 6 or X 5 and X 7 may be bonded to each other to form a cyclic structure.

[0059] The number of carbon atoms of the perfluoroalkyl group is preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 3. The perfluoroalkyl group may be linear or branched. Examples of the perfluoroalkyl group include a trimethylfluoromethyl group, a pentafluoroethyl group, etc.

[0060] The number of carbon atoms of the cyclic perfluoroalkyl group is preferably 6 to 8. Examples of the cyclic perfluoroalkyl group include a perfluorocyclohexyl group, etc.

[0061] X 5 X 6 X 7 and X 8From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of fluororesins, fluorine atoms and unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability of fluororesins, such as resistance to oxidative degradation, fluorine atoms and trifluoromethyl groups are more preferred, and fluorine atoms are even more preferred.

[0062] X 5 and X 6 , or X 5 and X 7 However, when the atoms are bonded to each other to form a cyclic structure, the cyclic structure may be, for example, a substituted or unsubstituted cyclic perfluoroalkyl structure having 5 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroether structure having 4 to 9 carbon atoms.

[0063] R 5 , and R 6 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 5 , R 6 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of fluororesins, fluorine atoms and unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability of fluororesins, such as resistance to oxidative degradation, fluorine atoms and trifluoromethyl groups are more preferred, with fluorine atoms being particularly preferred.

[0064] X 9 is a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, where Z is at least one selected from the group consisting of hydrogen atoms, alkali metal atoms, alkaline earth metal atoms, and amines, and X 9 The fluororesins may be crosslinked with each other by ionic crosslinking via the intermediary.

[0065] The alkali metal atoms are not particularly limited and include lithium atoms, sodium atoms, potassium atoms, rubidium atoms, cesium atoms, and francium atoms. Among these, lithium atoms, sodium atoms, and potassium atoms are preferred from the viewpoint of being easily available as raw materials and tending to reduce the manufacturing cost of fluororesins, and sodium atoms and potassium atoms are more preferred from the same viewpoint.

[0066] The alkaline earth metal atoms are not particularly limited and include beryllium, magnesium, calcium, strontium, barium, and radium atoms. Among these, magnesium and calcium atoms are preferred because they are readily available as raw materials and tend to reduce the manufacturing cost of fluororesin G1.

[0067] The amines are not particularly limited, including NH4, NH3R 30 NH2R 30 R 31 NHR 30 R 31 R 32 , NR 30 R 31 R 32 R 33 The structure is as follows: R 30 , R 31 , R 32 , R 33 These may be the same or different, and are substituted or unsubstituted aliphatic hydrocarbon groups having 1 to 10 carbon atoms, or substituted or unsubstituted aromatic hydrocarbon groups having 6 to 10 carbon atoms. Among these, from the viewpoint of ease of raw material availability and the tendency to suppress the manufacturing cost of fluororesins, unsubstituted aliphatic hydrocarbon groups having 1 to 6 carbon atoms and phenyl groups are preferred, unsubstituted aliphatic hydrocarbon groups having 1 to 4 carbon atoms are more preferred, and methyl groups or ethyl groups are even more preferred. 9 When fluororesins are crosslinked by ionic crosslinking, Z is an alkaline earth metal atom.

[0068] h, and p are numbers that satisfy 0 ≦ h < 1, 0 < p ≦ 1, and h + p = 1. i is an integer from 0 to 8. j is 0 or 1. k, l, and m may be the same or different from each other and are integers from 0 to 6 (however, when k, l, and m are simultaneously 0, X 9 is CF(CF2X 10 )2, and X 10 is a monovalent group represented by the formula -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, and Z is the same as described above. In addition, when it is "substituted", the substituents are the same as the substituents exemplified in General Formula 1.

[0069] In fluororesin G1, from the viewpoint that the chemical stability such as the oxidation degradation resistance of the fluororesin tends to be improved and from the viewpoint that the production cost of the fluororesin can tend to be suppressed, it is preferable to contain at least one selected from the structural unit represented by the following General Formula G2, the structural unit represented by the following General Formula G3, the structural unit represented by the following General Formula G4, and the structural unit represented by the following General Formula G5. -(CF2-CF2)- [G2] -(CF2-CF(-O-(CF2CFXO) N -A))- [G3] (In the formula, X is F or a perfluoroalkyl group having 1 to 3 carbon atoms, N is an integer from 0 to 5, and A is (CF2) M -SO3H (M represents an integer from 0 to 6. However, N and M do not become 0 simultaneously.)) -(CF2-CF(-O-(CF2) P -CFX(-O-(CF2) K -SO3H)))- [G4] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms, P represents an integer from 0 to 12, and K represents an integer from 1 to 5. However, P and K do not become 0 simultaneously.) -(CF2-CF(-O-(CF2) Q -CFX(-(CF2) L -O-(CF2) o -SO3H)))- [G5] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms, Q represents an integer of 0 to 12, L represents an integer of 1 to 5, and o represents an integer of 0 to 6. However, Q and o do not simultaneously become 0.)

[0070] It is more preferable that the fluororesin G1 contains at least one selected from the structural unit represented by the general formula G2, the structural unit represented by the general formula G3, the structural unit represented by the general formula G4, and the structural unit represented by the general formula G5. It is further preferable to contain the structural unit represented by the general formula G2 and the structural unit represented by the general formula G3 (where X is F or a trifluoromethyl group, N is an integer of 0 to 2, and M is an integer of 1 to 4). It is still further preferable to contain the structural unit represented by the general formula G2 and the structural unit represented by the general formula G3 (where X is F or a trifluoromethyl group, N is 0 or 1, and M is an integer of 2 to 4).

[0071] The structural unit represented by the general formula G1 in the fluororesin G1 is preferably a structural unit represented by the following general formula G1-2, and more preferably a structural unit represented by the following general formula G1-3.

[0072]

Chemical formula

[0073]

Chemical formula

[0075] Even when the fluororesin G1 has a high melt flow index (hereinafter also referred to as "MFI," measured in accordance with ASTM:D1238 (measurement conditions: temperature 270°C, load 2160g)) (i.e., has a low molecular weight), the partial crosslinking increases intermolecular entanglement and reduces solubility and excessive swelling.

[0076] Examples of the partial crosslinking reaction include the reaction of a functional group having ion-exchange capacity with a functional group or main chain of another molecule, or the reaction of functional groups having ion-exchange capacity with each other, or the crosslinking reaction (covalent bonding) via low molecular weight compounds, oligomers, or polymeric substances with excellent oxidation resistance, and in some cases, the reaction may also be with a salt-forming substance (including ionic bonding with a functional group having ion-exchange capacity). Examples of low molecular weight compounds, oligomers, or polymeric substances with excellent oxidation resistance include polyhydric alcohols and organic diamines.

[0077] The equivalent weight of fluororesin G1 is not particularly limited, but from the viewpoint of having excellent ion exchange capacity, it is preferably 2000 g / eq or less, more preferably 1500 g / eq or less, and even more preferably 1100 g / eq or less. For applications where fluororesin G1 is used as a film and the property of cation movement within the film is utilized, the resistance to cation movement tends to be reduced, so it is even more preferably 1050 g / eq or less, and even more preferably 1000 g / eq or less. Since the water resistance and chemical resistance of the fluororesin tend to be further improved, the equivalent weight of fluororesin G1 is even more preferably 500 g / eq or more, and even more preferably 700 g / eq or more. For applications where fluororesin is used as a film, the mechanical strength of the film tends to be improved, so it is preferably 800 g / eq or more, and even more preferably 880 g / eq or more. In this embodiment, equivalent weight refers to the dry mass in grams of ion-exchangeable resin per equivalent of ion-exchangeable groups in the case of ion-exchangeable resins, which are resins that have ion-exchange capacity, and to the dry mass in grams of fluororesin per equivalent of ion-exchangeable groups in the case of fluororesins. Hereafter, the expression "equivalent weight" will be used as appropriate. In addition, in measuring the equivalent weight, a method can be used in which the fluororesin is substituted with a salt and the solution is back-titrated with an alkaline solution. The equivalent weight can be appropriately adjusted by the copolymerization ratio of the monomers that are the raw materials of fluororesin G1, the selection of monomer species, etc.

[0078] <Method for producing fluororesin G1> The method for producing fluororesin G1 is not particularly limited, but examples include using a copolymer containing a fluoroolefin monomer represented by the following general formula G8 and a vinyl fluoride ether compound represented by at least one selected from the following general formulas G9, G10, and G11 as the precursor of fluororesin G1, followed by hydrolysis and acid treatment as described below. CFZ 1 =CZ 2 Z 3 [G8] (In the formula, Z 1 , Z 2 , Z 3 These elements may be the same or different, and are a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a cyclic perfluoroalkyl group, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. CF2 = CF - O - (CF2CFXO) N -A [G9] (In the formula, X is F or a perfluoroalkyl group having 1 to 3 carbon atoms, N is an integer from 0 to 5, and A is (CF2) M It is a functional group -W (where M is an integer between 0 and 6, and N and M cannot be 0 simultaneously), and W is a functional group that can be converted to a -SO3H group by hydrolysis and acid treatment. CF2 = CF - O - (CF2) P -CFX(-O-(CF2)K -W) [G10] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms, P represents an integer from 0 to 12, K represents an integer from 1 to 5 (however, P and K cannot be 0 at the same time), and W is a functional group that can be converted to a -SO3H group by hydrolysis and acid treatment.) CF2 = CF - O - (CF2) Q -CFX(-(CF2) L -O-(CF2) m -W)

[11] (In the formula, X is a perfluoroalkyl group having 1 to 3 carbon atoms, Q is an integer from 0 to 12, L is an integer from 1 to 5 (however, Q and L cannot be 0 at the same time), m is an integer from 0 to 6 (Q, L, and m cannot be 0 at the same time), and W is a functional group that can be converted to a -SO3H group by hydrolysis and acid treatment.)

[0079] Preferably, the method for producing fluororesin G1 involves using a copolymer of a fluoroolefin monomer represented by general formula G8 and a vinyl fluoride ether compound represented by at least one selected from the group consisting of general formulas G9, G10, and G11 as the precursor of fluororesin G1, followed by hydrolysis and acid treatment. From the viewpoint of improving the chemical stability of fluororesin G1, such as its resistance to oxidative degradation, and from the viewpoint of suppressing the production cost of fluororesin G1, general formula G8 (however, Z 1 , Z 2 , and Z 3 It is more preferably a fluorinated olefin monomer represented by the general formula G9 (where X is F or a trifluoromethyl group, N is an integer from 0 to 2, and M is an integer from 1 to 4), and a vinyl fluoride ether compound represented by the general formula G8 (where Z is 1 , Z 2 , and Z 3It is particularly preferable that the compound consists of a fluoroolefin monomer represented by the general formula G9 (where X is F or a trifluoromethyl group, N is 0 or 1, and M is an integer from 2 to 4). More preferably, it consists of a fluoroolefin monomer represented by the general formula G8 (where Z is F) and a vinyl fluoride ether compound represented by the general formula G9 (where X is F or a trifluoromethyl group, N is 0 or 1, and M is an integer from 2 to 4). 1 , Z 2 , and Z 3 This is a fluororesin G1 precursor consisting of a fluoroolefin monomer represented by F and a vinyl fluoride ether compound represented by general formula G9 (where X is a trifluoromethyl group, N is 1, and M is 2).

[0080] As the fluoroolefin monomer represented by general formula G8, the fluoroolefin monomer represented by general formula G12 is preferred, the fluoroolefin monomer represented by general formula G13 is more preferred, and the fluoroolefin monomer represented by general formula G14 is even more preferred. CF2=CFZ [G12] (In the formula, Z is H, Cl, F, a perfluoroalkyl group having 1 to 10 carbon atoms, or a cyclic perfluoroalkyl group which may contain oxygen as a ring constituent atom.) CF2=CFZ [G13] (In the formula, Z is F, a perfluoroalkyl group having 1 to 3 carbon atoms.) CF2 = CF2 [G14] As a vinyl fluoride ether compound represented by at least one selected from the group consisting of general formulas G9, G10, and G11, a vinyl fluoride ether compound represented by the following general formula G15 is preferred, and a vinyl fluoride ether compound represented by the following general formula G16 is more preferred. CF2 = CF - O - (CF2CFXO) n -A [G15] (wherein X is F, a trifluoromethyl group, n is 0 or 1, and A is (CF2) m It is a functional group called -W (where m is an integer between 2 and 4, and n and m cannot be both 0), and W is a functional group that can be converted to a -SO3H group by hydrolysis and acid treatment. CF2 = CF - O - (CF2CFXO) n -A [G16] (In the formula, X is a trifluoromethyl group, n is 1, and A is (CF2) m -W (where m is 2), and W is a functional group that can be converted to a -SO3H group by hydrolysis and acid treatment. In the above general formulas G9 to G11, G15, and G16, the functional group W, which can be converted to a -SO3H group by hydrolysis and acid treatment, is not particularly limited, but examples include SO2F, SO2Cl, SO2Br, SO2F and SO2Cl are preferred, and SO2F is more preferred.

[0081] The fluororesin G1 precursor in this embodiment can be produced by known means. For example, it can be produced by polymerizing a mixture containing a fluoroolefin monomer represented by the general formula G8 and a vinyl fluoride ether compound represented by at least one selected from the group consisting of general formulas G9, G10, and G11, in the presence of a radical generating agent such as a peroxide. The polymerization method is not particularly limited, but for example, it can be used to polymerize by filling and dissolving the gas of the fluoroolefin monomer and a vinyl fluoride ether compound, etc. in a polymerization solvent such as a fluorine-containing hydrocarbon and reacting them (solution polymerization); polymerizing by using a vinyl fluoride ether compound as the polymerization solvent without using a solvent such as a fluorine-containing hydrocarbon (bulk polymerization); polymerizing the gas of the fluoroolefin monomer and a vinyl fluoride ether compound, etc. using an aqueous solution of a surfactant as a medium (emulsification polymerization); polymerizing the gas of the fluoroolefin monomer and a vinyl fluoride ether compound, etc. by emulsifying them using an aqueous solution of a surfactant and an emulsifier such as an alcohol as a medium (emulsion polymerization); and polymerizing by suspending the gas of the fluoroolefin monomer and a vinyl fluoride ether compound, etc. in an aqueous solution of a suspension stabilizer as a medium and reacting them (suspension polymerization). The fluororesin G1 precursor in this embodiment can be any polymer prepared by any of the polymerization methods described above. Alternatively, block-shaped or tapered polymers obtained by adjusting polymerization conditions such as the supply amount of fluoroolefin monomer may also be used as the fluororesin G1 precursor. The fluororesin G1 precursor may be obtained by treating impure ends or structurally easily oxidized parts (such as CO groups and H bond parts) generated in the resin molecular structure during the polymerization reaction under fluorine gas using a known method, thereby fluorinating those parts. The fluororesin G1 precursor may have a portion of its ion-exchange group precursor group (e.g., -SO2F group) partially imidized (including intermolecularly) (e.g., alkylimidization).

[0082] The molecular weight of the fluororesin G1 precursor is not particularly limited, but it is preferably 0.05 g / 10 min or higher, more preferably 0.1 g / 10 min or higher, and even more preferably 0.5 g / 10 min or higher, based on the melt flow index (MFI) value measured in accordance with ASTM:D1238 (measurement conditions: temperature 270°C, load 2160 g). The MFI value is preferably 100 g / 10 min or lower, more preferably 80 g / 10 min or lower, and even more preferably 60 g / 10 min or lower.

[0083] The shape of the fluororesin G1 precursor is not particularly limited, but from the viewpoint of speeding up the treatment rate in the hydrolysis treatment and acid treatment described later, for example, 0.5 cm 3 The following forms are preferable: pellets, a dispersed liquid, or powder particles. Among these, the polymerized powder form is more preferable. From a cost standpoint, an extruded film-like fluororesin G1 precursor may also be used.

[0084] The method for producing the fluororesin G1 in this embodiment from the fluororesin G1 precursor is not particularly limited, but for example, the fluororesin G1 precursor may be melt-kneaded, then extruded using an extruder with a nozzle or die, and then subjected to the hydrolysis treatment described later, or the product of polymerization of the fluororesin G1 precursor may be used as is, in a dispersed liquid state, or precipitated and filtered into a powder, and then subjected to the hydrolysis treatment described later. These hydrolysis treatments yield fluororesin G1 in which Z in general formula G1 is an alkali metal atom or an alkaline earth metal atom. By subjecting the fluororesin G1 (Z=alkali metal atom, alkaline earth metal atom) to acid treatment, fluororesin G1 in which Z in general formula G1 is a hydrogen atom can be obtained. Furthermore, by reacting the fluororesin G1 (Z=hydrogen atom) with amines, fluororesin G1 in which Z in general formula G1 is an amine can be obtained.

[0085] Specifically, the fluororesin G1 precursor obtained as described above and molded as necessary can be further immersed in a basic reaction liquid and subjected to hydrolysis. The basic reaction liquid used for hydrolysis is not particularly limited, but examples include aqueous solutions of amine compounds such as dimethylamine, diethylamine, monomethylamine, and monoethylamine, and aqueous solutions of alkali metals or alkaline earth metal hydroxides. Among these, aqueous solutions of sodium hydroxide or potassium hydroxide are preferred. When alkali metals or alkaline earth metal hydroxides are used, the content is not particularly limited, but it is preferably 10% by mass or more and 30% by mass or less of the total basic reaction liquid. The basic reaction liquid is more preferably further containing swelling organic compounds such as methyl alcohol, ethyl alcohol, acetone, and dimethyl sulfoxide. The content of swelling organic compounds is preferably 1% by mass or more and 60% by mass or less of the total basic reaction liquid.

[0086] The fluororesin G1 precursor can be hydrolyzed in a basic reaction liquid, then thoroughly washed with warm water or the like as needed, and subsequently acid-treated to obtain a fluororesin having a structural unit in the general formula G1 in which Z is a hydrogen atom. The acid used for the acid treatment is not particularly limited, but examples include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as oxalic acid, acetic acid, formic acid, and trifluoroacetic acid. A mixture of the acid and water is preferred. The acid may be used individually or in combination of multiple types. The basic reaction liquid used in the hydrolysis treatment may be removed beforehand by treating it with a cation exchange resin or the like before the acid treatment. The hydrolyzed and acid-treated fluororesin G1 may be dispersible or soluble in a protic organic solvent, water, or a mixture thereof, and can be prepared as a suspension or a solution.

[0087] Since fluororesin G1 can sometimes improve mechanical strength, it is preferable that it be a fluororesin composition of two or more types of fluororesins with different structures of raw materials constituting fluororesin G1. By mixing two or more types of fluororesins, it may be possible to exhibit excellent properties by fusing the functions of each fluororesin. From the viewpoint of increasing crystallinity and improving mechanical strength, when mixing two or more types of fluororesins, it is preferable that the proportion of the fluororesin with a larger equivalent weight be greater than 50% by mass, more preferably greater than 55% by mass, and even more preferably greater than 60% by mass.

[0088] <Resin composition> The resin composition according to this embodiment includes a side-chain heteroaromatic resin and a cation-exchangeable resin. The weight ratio of the side-chain heteroaromatic resin to the cation exchange resin in the resin composition is not particularly limited, but is preferably 1:100 to 100:1. Depending on the application of the resin composition according to this embodiment, when used as a diaphragm for a redox flow battery, the weight ratio of the side-chain heteroaromatic resin to the cation exchange resin is preferably 10:90 or higher, more preferably 20:80 or higher, and even more preferably 30:70 or higher, from the viewpoint of suppressing the elution of the side-chain heteroaromatic resin into the electrolyte. Depending on the application of the mixture, when used as a diaphragm for a redox flow battery, the weight ratio of the side-chain heteroaromatic resin tends to improve power efficiency, so it is preferably 90:10 or lower, more preferably 80:20 or lower, and even more preferably 70:30 or lower.

[0089] The resin composition according to this embodiment preferably comprises styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, polyether ether ketone resin, polysulfone resin, polyether sulfone resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, polyphenylene ether resin, polyphenylene sulfide resin, syndiotactic polystyrene resin, polyetherimide, siloxane-modified polyetherimide resin, polyamideimide resin, cycloolefin resin, cycloolefin copolymer, polyether ketone ether ketone ketone resin, polyallyl ether ketone resin, and perfluoro resin, and may further comprise styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, syndiotactic polystyrene resin, cycloolefin resin, and cycloolefin copolymer. The resins that may be included in the resin composition according to this embodiment may be used individually or in combination of multiple types.

[0090] <Ion exchange membrane> The ion exchange membrane according to this embodiment includes a side-chain heteroaromatic resin having a structural unit represented by general formula 1, a side-chain heteroaromatic resin having a structural unit represented by general formula 2, or a resin composition according to this embodiment.

[0091] When forming a film from a side-chain heteroaromatic resin having structural units represented by general formula 1, a side-chain heteroaromatic resin having structural units represented by general formula 2, or a resin composition according to this embodiment, the molding method is not particularly limited. Examples include a method of processing a substance containing the side-chain heteroaromatic resin or the resin composition according to this embodiment into a film by extruding it using an extruder with a nozzle or die, or a method of processing a film by coating the side-chain heteroaromatic resin or the resin composition according to this embodiment onto a substrate using a die, gravure roll, knife, or spray while it is in a solution state and drying it. The resulting film of the side-chain heteroaromatic resin or the resin composition according to this embodiment will also be referred to as a side-chain heteroaromatic resin film below. The solvents that can be used when preparing the side-chain heteroaromatic resin or resin composition as a solution are not particularly limited and include saturated hydrocarbon compounds such as n-pentane, n-hexane, n-octane, n-decane, cyclopentane, cyclohexane, and cyclooctane; aromatic hydrocarbon compounds such as benzene, toluene, xylene, and ethylbenzene; halogenated hydrocarbon compounds such as methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, and dichlorobenzene; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, cyclohexanol, and benzyl alcohol; acetone, ethyl methyl ketone, methyl butyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples include ketones such as ethyl acetate, butyl acetate, and methyl benzoate; ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, and dioxane; polyols such as ethylene glycol, propylene glycol, and glycerin, and polymers of compounds having two hydroxyl groups among the polyols; and esterified compounds of the polymers, nitriles such as acrylonitrile and benzonitrile; nitromethane; N,N-dimethylformamide; dimethyl sulfoxide; hexamethylphosphoric triamide; carbon disulfide; fluorinated compounds (e.g., Novec™ manufactured by 3M, Asahiclean manufactured by Asahi Glass Co., Ltd., etc.). These solvents may be used individually or in combination.

[0092] When forming the side-chain heteroaromatic resin or resin composition according to this embodiment into a film, a substrate can also be used. By using a substrate, it may be possible to manufacture the film of the side-chain heteroaromatic resin or resin composition according to this embodiment more stably. The substance used in the base material is not particularly limited, and examples include polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, cycloolefin polymer, polycarbonate, polyamide, polyimide, polyamide-imide, polyvinyl chloride, polystyrene, polyphenylene ether, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide resin, polyether ketone, polyether ketone, polyallyl ether ketone, etc. The substance may be modified, and may be used alone or in combination of multiple substances.

[0093] The ion exchange membrane according to this embodiment comprises a layer (L) containing the aforementioned resin composition and a structural unit represented by the following general formula G1. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) The material has at least one alternating layer (M) containing a fluororesin and a layer (M) containing a fluororesin.

[0094] By using a membrane containing a fluororesin (hereinafter also referred to as a fluororesin membrane) as the base material for layer (M), an ion exchange membrane having a fluororesin membrane (layer (M)) and a side-chain heteroaromatic resin membrane (layer (L)) can be obtained. Note that layer (M) does not necessarily have to contain a side-chain heteroaromatic resin. The ion exchange resin according to this embodiment may have one layer (L) and one layer (M) (a film having one layer (M) and one layer (L) is also called a "bipolar film"). By forming a laminated film, an ion exchange film can be made that combines the characteristics of both a fluororesin film and a side-chain heteroaromatic resin film. In the following, when the films are laminated, the fluororesin film will also be referred to as the fluororesin layer, and the side-chain heteroaromatic resin film will also be referred to as the side-chain heteroaromatic resin layer.

[0095] Furthermore, the interface between the layer (L) containing the side-chain heteroaromatic resin in the ion exchange membrane and the layer (M) containing the fluororesin having a structural unit represented by general formula G1 is determined by the value at which the maximum signal intensity of the peak characteristic of the side-chain heteroaromatic resin is 1 / 10, as measured by a time-of-flight secondary ion mass spectrometer, with reference to JIS K 0146:2002. The region where the maximum signal intensity of the peak characteristic of the side-chain heteroaromatic resin is 1 / 10 or more is defined as layer (L), and the region where the maximum signal intensity of the peak characteristic of the side-chain heteroaromatic resin is less than 1 / 10 is defined as layer (M).

[0096] The method for producing a fluororesin film (layer (M)) is not particularly limited, and can be obtained by processing a resin composition containing fluororesin G1 into a film, or by processing a resin composition containing a fluororesin G1 precursor having ion-exchange functional groups by hydrolysis into a film, and then performing the aforementioned hydrolysis treatment and acid treatment. For example, one method is to melt-knead a resin composition containing fluororesin, and then extrude it using an extruder with a nozzle or die to form a film. Another method is to melt-knead a resin composition containing a fluororesin G1 precursor, then extrude it using an extruder with a nozzle or die to form a film, and then perform hydrolysis treatment and acid treatment to form ion-exchange groups. Alternatively, a substance containing fluororesin may be dispersed in a solvent and then cast onto a substrate to form a film.

[0097] The layer (L) can be produced by a molding method that forms a film using a side-chain heteroaromatic resin having structural units represented by the aforementioned general formula 1, a side-chain heteroaromatic resin having structural units represented by general formula 2, or the resin composition according to this embodiment.

[0098] By repeatedly applying the method for producing a side-chain heteroaromatic resin film and the method for producing a fluororesin film to the aforementioned laminated film, a film can be produced in which a side-chain heteroaromatic resin film and a fluororesin film are laminated in multiple layers.

[0099] A multilayer film can also be manufactured by laminating bipolar films with alternating side-chain heteroaromatic resin films and fluororesin films, and then pressing the films together. Furthermore, a three-layer film can be manufactured by laminating two bipolar films with side-chain heteroaromatic resin films together, or two fluororesin films together, and then pressing the films together.

[0100] The side-chain heteroaromatic resin membrane of this embodiment and the ion exchange membrane having the side-chain heteroaromatic resin membrane and the fluororesin membrane (the ion exchange membrane is not particularly limited as long as it has two or more layers, and the same applies hereafter) can be used for various applications. Examples of such applications include redox flow batteries, fuel cells, sodium chloride electrolysis, alkaline water electrolysis, carbon dioxide reduction electrolysis, etc. Among these, redox flow battery cells and redox flow batteries are particularly suitable examples. When used in redox flow battery cells and redox flow batteries, they tend to have superior power efficiency compared to conventionally used diaphragms.

[0101] The total thickness of the ion exchange membrane in this embodiment is not particularly limited, but in the redox flow battery cell and redox flow battery exemplified as suitable applications, it is preferably 0.01 μm to 200 μm, as handling and mechanical strength of the membrane tend to improve. It is more preferably 1 μm or more, and especially preferably 10 μm or more, and particularly preferably 20 μm or more, when membrane pulsation is large and high mechanical strength is required. The total thickness of the ion exchange membrane in this embodiment is more preferably 150 μm or less, even more preferably 130 μm or less, and particularly preferably 100 μm or less, as electrical resistance when the redox flow battery cell and redox flow battery are operated is suppressed and power efficiency tends to improve.

[0102] In the ion exchange membrane of this embodiment, the thickness of layer (L) (side-chain heteroaromatic resin membrane) is not particularly limited, but in the redox flow battery cell and redox flow battery exemplified as suitable applications, it is preferably 0.01 μm to 10 μm, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more, as this tends to further suppress the permeation of redox active substances through the membrane when used in a redox flow battery cell and redox flow battery. When the pulsation of the side-chain heteroaromatic resin membrane is large and high mechanical strength is required, the thickness of layer (L) (side-chain heteroaromatic resin membrane) is particularly preferably 0.3 μm or more, even more preferably 0.4 μm or more, as this tends to suppress electrical resistance when operating a redox flow battery cell and redox flow battery, and improve power efficiency.

[0103] The equivalent weight of the ion exchange membrane is not particularly limited, but is preferably 500 g / eq or more and 2000 g / eq or less, as this tends to improve the handling and mechanical strength of the membrane. It is more preferably 700 g / eq or more, even more preferably 800 g / eq or more, and especially preferably 880 g / eq or more, and even more preferably 900 g / eq or more, as this tends to improve the handling and mechanical strength of the membrane. The equivalent weight of the ion exchange membrane is more preferably 1500 g / eq or less, even more preferably 1400 g / eq or less, especially preferably 1200 g / eq or less, and even more preferably 1150 g / eq or less, as this tends to suppress the electrical resistance when operating the redox flow battery cell and the redox flow battery, thereby improving power efficiency.

[0104] [Second Embodiment] Next, a second embodiment will be described.

[0105] Patent Document 1 discloses the use of an aromatic polysulfone polymer as an anion exchange base layer to improve current efficiency and power efficiency. However, it has been shown that while current efficiency is excellent, cell resistance increases and voltage efficiency decreases. Therefore, there is a need for an anion exchange base layer that offers a good balance of current efficiency, voltage efficiency, and current efficiency. Patent Document 2 discloses Nafion® 117, which is produced by reacting several heterocyclic molecules to improve vanadium ion permeability selectivity while suppressing an increase in proton surface resistance. However, lowering the proton surface resistance leads to lower vanadium ion permeability selectivity, while increasing the vanadium ion permeability selectivity leads to higher proton surface resistance, and achieving both simultaneously remains a challenge. Furthermore, the examples were not evaluated as redox flow batteries, so the current efficiency, voltage efficiency, and power efficiency are unknown. However, since the proton surface resistance in the examples is higher than that of Nafion® 117, it can be inferred that the voltage efficiency is lower than that of Nafion® 117. For these reasons, there is a need for a material that offers a good balance of current efficiency, voltage efficiency, and power efficiency. Patent Document 3 discloses a crossover prevention layer, which is a metal layer formed by reducing a cationic metal inside a polymer electrolyte membrane, in order to improve at least one of the characteristics of discharge capacity, current efficiency, voltage efficiency, and power efficiency. However, there is a need for even higher characteristics. Patent Document 4 discloses the use of several polymer compounds as an anion-exchangeable resin layer to achieve high power efficiency. However, it has been shown that when an anion-exchangeable resin layer is not located between the ion-exchangeable resin layer and the anion-exchangeable resin layer, high power efficiency may be obtained as an initial characteristic, but high power efficiency cannot be obtained after 100 cycles. For this reason, there is a need for the anion-exchangeable compound contained in the anion-exchangeable resin layer used in Patent Document 4 to have even higher properties.

[0106] The object of this embodiment is an ion exchange membrane, a membrane electrode assembly, a redox flow battery cell, and a redox flow battery, which can be obtained that have a well-balanced and excellent current efficiency and voltage efficiency and high power efficiency for a redox battery cell.

[0107] As a result of diligent research into the above-mentioned problems, the present inventors have found that by using a heteroaromatic structure-containing fluororesin having a specific structural unit, its saponide, or its salt as an ion exchange membrane, it is possible to provide a redox battery cell that exhibits a good balance of current efficiency and voltage efficiency, as well as high power efficiency.

[0108] <Ion exchange membrane according to the second embodiment> The ion exchange membrane according to the second embodiment comprises a layer (L1) containing a heteroaromatic structure-containing fluororesin having a structural unit represented by the following general formula A1, its saponide, or its salt, [ka] (In the formula, X 1 , X 2 , X 3 , and X 4 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 1 and X 2 , or X 1 and X 3 These may be bonded to each other to form a ring structure. R 1 , R 2 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. R 3is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 1 to 10 carbon atoms, R 4 is NR 3 is a linking group between NR X 10 and Hc, and is a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms, Hc is a substituted or unsubstituted heteroaromatic group having 4 to 30 carbon atoms, containing at least one nitrogen atom and including a 5-membered ring and / or a 6-membered ring structure, a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1, b is an integer from 0 to 8, c is 0 or 1, d, e, and f may be the same or different from each other and are integers from 0 to 6. However, d, e, and f are not 0 at the same time.) A layer (M1) containing a fluororesin (G1) having a structural unit represented by the general formula G1, has

[0109] According to the present embodiment, an ion exchange membrane, a membrane electrode assembly, a redox flow battery cell, and a redox flow battery can be provided, which have excellent balance between current efficiency and voltage efficiency and have high power efficiency for a redox battery cell.

[0110] <Heteroaromatic structure-containing fluororesin> The heteroaromatic structure-containing fluororesin according to the present embodiment has a structural unit represented by the following general formula A-1.

Chemical formula

[0111] X 1 、X 2 、X 3, and X 4 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 1 and X 2 , or X 1 and X 3 These may be bonded to each other to form a ring structure. 1 , X 2 , X 3 and X 4 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of heteroaromatic structure-containing fluororesins, fluorine atoms or unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability, such as the resistance to oxidation degradation of heteroaromatic structure-containing fluororesins, fluorine atoms and trifluoromethyl groups are more preferred, and fluorine atoms are particularly preferred.

[0112] R 1 , and R 2 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 1 , and R 2 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of heteroaromatic structure-containing fluororesins, fluorine atoms and unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability, such as the resistance to oxidation degradation of heteroaromatic structure-containing fluororesins, fluorine atoms or trifluoromethyl groups are more preferred, and fluorine atoms are particularly preferred.

[0113] In the case of "substitution," the substituents are the same as those exemplified in General Formula 1.

[0114] R3 R is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. 3 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of heteroaromatic structure-containing fluororesins, hydrogen atoms and aliphatic hydrocarbon groups having 1 to 10 carbon atoms are preferred, and hydrogen atoms and unsubstituted aliphatic hydrocarbon groups having 1 to 4 carbon atoms are more preferred. From the viewpoint of further suppressing the manufacturing cost of heteroaromatic structure-containing fluororesins, hydrogen atoms are even more preferred, and from the viewpoint of improving the stability of heteroaromatic structure-containing fluororesins under alkaline conditions, unsubstituted aliphatic hydrocarbon groups having 1 to 2 carbon atoms are even more preferred. In the case of "substituted," the substituents are the same as those exemplified in General Formula 1.

[0115] R 4 , NR 3 It is a linking group to Hc, and is a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. 4 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of heteroaromatic structure-containing fluororesins, unsubstituted aliphatic hydrocarbon groups having 1 to 10 carbon atoms are preferred, unsubstituted aliphatic hydrocarbon groups having 1 to 6 carbon atoms are more preferred, and unsubstituted aliphatic hydrocarbon groups having 1 to 4 carbon atoms are even more preferred. From the viewpoint of improving the chemical stability, such as the resistance to oxidative degradation, of heteroaromatic structure-containing fluororesins, unsubstituted aliphatic hydrocarbon groups having 1 to 2 carbon atoms are particularly preferred, and unsubstituted aliphatic hydrocarbon groups having 1 carbon atom are even more particularly preferred. In the case of "substituted," the substituents are the same as those exemplified in General Formula 1.

[0116] X 10 This is a divalent group represented by the formulas -CO2- and -SO2-. From the viewpoint of improving the chemical stability, such as the resistance to oxidative degradation, of the heteroaromatic structure-containing fluororesin, the divalent group represented by the formula -SO2- is preferred.

[0117] Hc is a heteroaromatic group having 4 to 30 carbon atoms, containing at least one substituted or unsubstituted nitrogen atom, and including a 5-membered ring and / or 6-membered ring structure. The five-membered ring and / or six-membered ring structure in Hc is not particularly limited, but examples include imidazole structures, benzimidazole structures, imidazopyridine structures, pyridine structures, oxazole structures, thiazole structures, pyridazine structures, pyrimidine structures, sinnoline structures, quinazoline structures, phthalazine structures, quinoxaline structures, pteridine structures, purine structures, 2,2'-bipyridyl structures, 2,3'-bipyridyl structures, 2,4'-bipyridyl structures, 1,7-phenanthroline structures, 1,10-phenanthroline structures, and 2,2':6',2''-terpyridine structures. The Hc structures described above may be used individually or in combination of multiple structures.

[0118] Since Hc has at least one nitrogen atom in its heteroaromatic ring structure, among the above-mentioned 5-membered ring and / or 6-membered ring structures, it is preferable that the structure is an imidazole structure, a benzimidazole structure, an imidazopyridine structure, a pyridine structure, an oxazole structure, a thiazole structure, a 2,2'-bipyridyl structure, a 2,3'-bipyridyl structure, a 2,4'-bipyridyl structure, a 1,7-phenanthroline structure, or a 1,10-phenanthroline structure, and among the above-mentioned 5-membered ring and / or 6-membered ring structures, it is preferable that the structure is an imidazole structure, a benzimidazole structure, or an i It is more preferable to have a midazopyridine structure, a pyridine structure, an oxazole structure, a thiazole structure, a 2,2'-bipyridyl structure, or a 1,10-phenanthroline structure. When a heteroaromatic structure-containing fluororesin is used in a redox flow battery cell, durability tends to improve, so it is even more preferable to have an imidazole structure, a benzimidazole structure, an imidazopyridine structure, or a pyridine structure, and it is particularly preferable to have an imidazole structure or a pyridine structure.

[0119] H C The substituents in are the same as those exemplified in General Formula 1.

[0120] Examples of Hc include imidazolyl group, benzimidazolyl group, imidazopyridinyl group, pyridinyl group, oxazonyl group, thiazolyl group, pyridadinyl group, pyrimidinyl group, synnolinyl group, quinazolinyl group, phthalazinyl group, quinoxalinyl group, pteridinyl group, prinyl group, 2,2'-bipyridinyl, 2,3'-bipyridinyl group, 2,4'-bipyridinyl group, 1,7-phenanthrolinyl group, 1,10-phenanthrolinyl group, and 2,2':6',2''-terpyridinyl group. Among these, imidazolyl group or pyridinyl group is preferred.

[0121] In the above-mentioned heteroaromatic structure-containing fluororesin, from the viewpoint of improving the chemical stability of the heteroaromatic structure-containing fluororesin, such as its resistance to oxidative degradation, and from the viewpoint of suppressing the manufacturing cost of the heteroaromatic structure-containing fluororesin and thereby suppressing the manufacturing cost of redox flow battery cells, it is preferable to include at least one selected from the group consisting of a structural unit represented by general formula A2, a structural unit represented by general formula A4 below, a structural unit represented by general formula A5 below, and a structural unit represented by general formula A6 below. -(CF2-CF2)-[A2] -(CF2-CF(-O-(CF2CFXO) N -Ag))- [A4] (In the formula, X represents F or a perfluoroalkyl group having 1 to 3 carbon atoms. Ag represents (CF2) in the general formula A1 above.) f -X 10 -NR 3 -R 4 -Hc indicates. N represents an integer from 0 to 5. ) indicates. ), -(CF2-CF(-O-(CF2) P -CFX(-O-(CF2) K -SO2NX 41 Ax)))- [A5] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms. X 41is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is -R in the general formula A1 above. 4 This represents -Hc. P represents an integer between 0 and 12, and K represents an integer between 1 and 5. However, P and K cannot be 0 simultaneously. -(CF2-CF(-O-(CF2) Q -CFX(-(CF2) L -O-(CF2) o -SO2NX 41 Ax)))- [A6] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms. X 41 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is -R in the general formula A1 above. 4 -Hc represents an integer between 0 and 12, L represents an integer between 1 and 5, and o represents an integer between 0 and 6. However, Q and O cannot be 0 at the same time.

[0122] The heteroaromatic structure-containing fluororesin more preferably comprises a structural unit represented by general formula A2 and at least one selected from the group consisting of a structural unit represented by general formula A4, a structural unit represented by general formula A5, and a structural unit represented by general formula A6; more preferably contains a structural unit represented by general formula A2 and a structural unit represented by general formula A4 (wherein X is F or a trifluoromethyl group, N is an integer from 0 to 2, and f is an integer from 1 to 4); and particularly preferably contains a structural unit represented by general formula A2 and a structural unit represented by general formula A4 (wherein X is F or a trifluoromethyl group, N is 0 or 1, and f is an integer from 2 to 4).

[0123] The heteroaromatic structure-containing fluororesin more preferably contains structural units represented by the following general formula A1-1, and even more preferably contains structural units represented by the following general formula A1-2. -[CF2CF2] a-[CF2-CF((-O-CF2-(CF(CF3))) b -O-(CF2)2-SO2NX 41 Ax)] g - [A1-1] (In the formula, X 41 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is -R in the above general formula A1 4 -Hc. a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1. b is 0 or 1.) -[CF2CF2] a -[CF2-CF((-O-CF2-(CF(CF3)))-O-(CF2)2-SO2NX 41 Ax)] g - [A1-2] (In the formula, X 41 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is -R in the above general formula A1 4 -Hc. a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1.)

[0124] In the above general formulas A5, A6, A1-1, and A1-2, from the viewpoint that the raw materials are easily available and the production cost of the fluororesin containing a heteroaromatic structure tends to be suppressed, X 41 is preferably a hydrogen atom or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an unsubstituted aliphatic hydrocarbon group having 1 to 4 carbon atoms. From the viewpoint that the production cost of the fluororesin containing a heteroaromatic structure can be further suppressed, a hydrogen atom is even more preferable, and from the viewpoint that the stability of the fluororesin containing a heteroaromatic structure under alkaline conditions is improved, an unsubstituted aliphatic hydrocarbon group having 1 to 2 carbon atoms is even more preferable.)

[0125] The method for producing a heteroaromatic structure-containing fluororesin is not particularly limited, but an example is a method in which a fluororesin precursor, described later, is reacted with a modified compound. The modified compound has at least two nitrogen atom-containing groups. Of these nitrogen atom-containing groups, at least one is a heteroaromatic group (corresponding to Hc) having 4 to 30 carbon atoms, containing at least one nitrogen atom, and including a 5-membered ring and / or 6-membered ring structure, either substituted or unsubstituted. Furthermore, of these nitrogen atom-containing groups, at least one is a primary amino group or a secondary amino group. From the viewpoint of improving the reactivity between the modified compound and the fluororesin precursor, it is preferable to be a primary amino group, and from the viewpoint of improving the stability of the heteroaromatic structure-containing fluororesin, it is preferable to be a secondary amino group. In addition to these, other nitrogen atom-containing groups that may be included in the modified compound include: An amino salt structure comprising at least one amino group selected from the group consisting of primary amino groups, secondary amino groups, and tertiary amino groups, and at least one substance selected from the group consisting of acidic substances and halogen atom-containing aliphatic hydrocarbon compounds. A salt structure of a nitrogen atom-containing heterocyclic structure and at least one selected from the group consisting of acidic substances and halogen atom-containing aliphatic hydrocarbon compounds, Examples include quaternary ammonium groups. However, the quaternary ammonium group is a quaternary ammonium group that is different from the amino salt structure and the salt structure mentioned above.

[0126] More specifically, modified compounds include, for example, 1-(3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, isonicotinamide, 4-(ethylaminomethyl)pyridine, 4-(4-piperidyl)pyridine, 2-methyltryptamine, 5-methoxytryptamine, 6-methoxytryptamine, necrostatin-1, alosetron, sulfamethoxypyridazine, and 1-(3-chloroanilino)-4-phenylphthalate. Examples include radin, 4-amino-5-aminomethyl-2-methylpyrimidine, 2-(aminomethyl)-5-methylpyrazine, 2-(4-piperidinyl)benzimidazole, 2-(4-aminophenyl)benzimidazole, 5-amino-2-(4-aminophenyl)benzimidazole, 6-(aminomethyl)quinoline, 2-methyl-7-[phenyl(phenylamino)methyl]-8-quinolinol, and 1-(2-amino-1-naphthyl)isoquinoline. These modified compounds may be used individually or in combination.

[0127] From the perspective of readily available modified compounds and the tendency to reduce the manufacturing costs of heteroaromatic structure-containing fluororesins, 1-(3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, isonicotinamide, 4-(ethylaminomethyl)pyridine, 4-(2-aminoethyl)pyridine, 4-(4-piperidyl)pyridine, 2-(4-piperidinyl)benzimidazole, 2-(4-aminophenyl)benzimidazole, and 5-amino-2-(4-aminophenyl)benzimidazole are considered. It is preferable that it be at least one selected from the group consisting of 1-(3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, isonicotinamide, 4-(4-piperidyl)pyridine, and 2-(4-aminophenyl)benzimidazole, and even more preferably that it is at least one selected from the group consisting of 1-(3-aminopropyl)imidazole, 4-picolylamine, and 4-(2-aminoethyl)pyridine.

[0128] The heteroaromatic structure-containing fluororesin in this embodiment has a sulfonamide bond (-SO2NR-) (wherein R in the formula representing sulfonamide is not particularly limited). The presence of a sulfonamide bond in the heteroaromatic structure-containing fluororesin can be analyzed by general analytical methods, and analytical instruments such as FT-IR and TOF-SIMS can be used.

[0129] The heteroaromatic structure-containing fluororesin in this embodiment may be a saponified or salt thereof.

[0130] The saponified product of the heteroaromatic structure-containing fluororesin is a saponified product obtained by reacting the heteroaromatic structure-containing fluororesin with an alkaline substance. Examples of basic substances include amine compounds such as dimethylamine, diethylamine, monomethylamine, and monoethylamine, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides. Among these, sodium hydroxide or potassium hydroxide is preferred.

[0131] Salts of heteroaromatic structure-containing fluororesins are salts of heteroaromatic structure-containing fluororesins with acidic substances. Examples of acidic substances include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as oxalic acid, acetic acid, formic acid, and trifluoroacetic acid.

[0132] <Fluororesin G1> The hetero-aromatic structure-containing fluororesin in this embodiment may be used as a resin composition mixed with other resins. The resin composition may include the heteroaromatic structure-containing fluororesin and fluororesin G1 in this embodiment. In this embodiment, a mixture of fluororesins, such as a composition containing a heteroaromatic structure-containing fluororesin and fluororesin G1, is referred to as a resin composition. Fluororesin G1 is a fluororesin that has ion exchange capacity for cations (hereinafter also referred to as "positive ions").

[0133] Fluororesin G1 has structural units represented by the following general formula G1. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) The preferred fluororesin G1 is as described above.

[0134] The weight ratio of the heteroaromatic structure-containing fluororesin to the fluororesin G1 in the resin composition is not particularly limited, but is preferably 1:100 to 100:1. Depending on the application of the resin composition according to this embodiment, when used as a diaphragm for a redox flow battery, the weight ratio of the heteroaromatic structure-containing fluororesin to the fluororesin G1 is preferably 5:95 or higher, more preferably 10:90 or higher, and even more preferably 15:85 or higher, from the viewpoint of suppressing the elution of the heteroaromatic structure-containing fluororesin into the electrolyte. Depending on the application of the mixture, when used as a diaphragm for a redox flow battery, the weight ratio of the heteroaromatic structure-containing fluororesin tends to improve power efficiency, so it is preferably 90:10 or lower, more preferably 80:20 or lower, and even more preferably 70:30 or lower.

[0135] The content of the heteroaromatic structure-containing fluororesin in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Depending on the application in which the mixture is used, when used as a diaphragm for redox flow batteries, the power efficiency tends to be improved by the heteroaromatic structure-containing fluororesin, so the content of the heteroaromatic structure-containing fluororesin in the resin composition is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0136] When using a fluororesin containing a heteroaromatic structure having a structural unit represented by general formula A1, the ratios of various resins are exemplified as follows. The weight ratio of the side-chain nitrogen atom-containing fluororesin to fluororesin G1 in the resin composition is not particularly limited, but is preferably 1:100 to 100:1. Depending on the application of the resin composition according to this embodiment, when used as a diaphragm for a redox flow battery, the weight ratio of the side-chain nitrogen atom-containing fluororesin to fluororesin G1 is preferably 10:90 or higher, more preferably 20:80 or higher, and even more preferably 30:70 or higher, from the viewpoint of suppressing the elution of the heteroaromatic structure-containing fluororesin into the electrolyte. Depending on the application of the mixture, when used as a diaphragm for a redox flow battery, the weight ratio of the side-chain nitrogen atom-containing fluororesin tends to improve power efficiency, so it is preferably 90:10 or lower, more preferably 80:20 or lower, and even more preferably 70:30 or lower.

[0137] The content of side-chain nitrogen atom-containing fluororesin in the resin composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. Depending on the application in which the mixture is used, when used as a diaphragm for redox flow batteries, the power efficiency tends to be improved by the side-chain nitrogen atom-containing fluororesin, so the content of side-chain nitrogen atom-containing fluororesin in the resin composition is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0138] The resin composition according to this embodiment preferably comprises styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, polyether ether ketone resin, polysulfone resin, polyether sulfone resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, polyphenylene ether resin, polyphenylene sulfide resin, syndiotactic polystyrene resin, polyetherimide, siloxane-modified polyetherimide resin, polyamideimide resin, cycloolefin resin, cycloolefin copolymer, polyether ketone ether ketone ketone resin, polyallyl ether ketone resin, and fluororesin, and may further comprise styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, syndiotactic polystyrene resin, cycloolefin resin, and cycloolefin copolymer. The resins that may be included in the resin composition according to this embodiment may be used individually or in combination of multiple types.

[0139] <Ion exchange membrane> The ion exchange membrane according to this embodiment comprises a fluororesin containing a heteroaromatic structure, or a resin composition according to this embodiment.

[0140] When forming a resin composition containing a heteroaromatic structure-containing fluororesin into a film, the molding method is not particularly limited. Examples include a method in which the resin composition containing the heteroaromatic structure-containing fluororesin is in a molten state and processed into a film by extrusion molding using an extruder with a nozzle or die, or a method in which the resin composition containing the heteroaromatic structure-containing fluororesin is in a solution state and coated onto a substrate using a die, gravure roll, knife, or spray, and then dried to form a film. The resulting film of the heteroaromatic structure-containing fluororesin will also be referred to as the heteroaromatic structure-containing fluororesin film below.

[0141] The solvents that can be used when preparing a fluororesin containing a heteroaromatic structure as a solution are not particularly limited and include, for example, saturated hydrocarbon compounds such as n-pentane, n-hexane, n-octane, n-decane, cyclopentane, cyclohexane, and cyclooctane; aromatic hydrocarbon compounds such as benzene, toluene, xylene, and ethylbenzene; halogenated hydrocarbon compounds such as methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, and dichlorobenzene; alcohols such as methanol, ethanol, propanol, isopropanol, butanol hexanol, cyclohexanol, and benzyl alcohol; acetone, ethyl methyl ketone, methyl butyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples include ketones such as ethyl acetate, butyl acetate, and methyl benzoate; ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, and dioxane; polyols such as ethylene glycol, propylene glycol, and glycerin, and polymers of compounds having two hydroxyl groups among the polyols; and esterified compounds of the polymers, nitriles such as acrylonitrile and benzonitrile; nitromethane; N,N-dimethylformamide; dimethyl sulfoxide; hexamethylphosphoric triamide; carbon disulfide; fluorinated compounds (e.g., Novec™ manufactured by 3M, Asahiclean manufactured by Asahi Glass Co., Ltd., etc.). The solvent may be used alone or in combination of several types.

[0142] When forming a film from a composition containing a heteroaromatic structure-containing fluororesin, a substrate can also be used. Using a substrate may allow for more stable production of the film from the heteroaromatic structure-containing fluororesin composition. The materials used as the base material are not particularly limited, and examples include polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, cycloolefin polymer, polycarbonate, polyamide, polyimide, polyamide-imide, polyvinyl chloride, polystyrene, polyphenylene ether, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide resin, polyether ketone, polyallyl ether ketone, etc. The materials used as the base material may be modified, and may be used individually or in combination of multiple materials.

[0143] The ion exchange membrane according to this embodiment comprises a layer (L1) containing the aforementioned heteroaromatic structure-containing fluororesin, and a structural unit represented by the following general formula G1. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) It has at least one alternating layer of fluororesin (M1) and .

[0144] By using a membrane containing fluororesin G1 (hereinafter also referred to as a fluororesin membrane) as the base material for layer (M1), an ion exchange membrane having a fluororesin membrane (M1) and a heteroaromatic structure-containing fluororesin membrane (L1) can be obtained. Note that layer (M1) does not necessarily have to contain a heteroaromatic structure-containing fluororesin. The ion exchange resin according to this embodiment may have one layer (L1) and one layer (M1) (an ion exchange membrane having one layer (L1) and one layer (M1) is also called a "bipolar membrane"). By forming a laminated membrane, an ion exchange membrane can be made that combines the respective properties of fluororesin G1 and heteroaromatic structure-containing fluororesin. In the following, when the membranes are laminated, the fluororesin membrane will also be called the fluororesin layer, and the heteroaromatic structure-containing fluororesin membrane will also be called the heteroaromatic structure-containing fluororesin layer.

[0145] Furthermore, the interface between the layer containing a heteroaromatic structure-containing fluororesin (L1) in the ion exchange membrane and the layer containing a fluororesin having a structural unit represented by general formula G1 (M1) is determined by the value at which the maximum signal intensity of NSO2 (m / z 78, two peaks are detected, but the lower mass side is used), measured by a time-of-flight secondary ion mass spectrometer, is 1 / 10, in reference to JIS K 0146:2002. The region where the maximum signal intensity of the NSO2 peak is 1 / 10 or more is defined as layer (L), and the region where the maximum signal intensity of the NSO2 peak is less than 1 / 10 is defined as layer (M).

[0146] The method for manufacturing the fluororesin film is as described above.

[0147] As a method for forming a film of a heteroaromatic structure-containing fluororesin, a heteroaromatic structure-containing fluororesin film can be produced by reacting a fluororesin G1 precursor film with a modified compound and then subjecting it to hydrolysis. Furthermore, acid treatment can also be performed. In other words, hydrolysis treatment can produce a saponide of the heteroaromatic structure-containing fluororesin film, and further acid treatment can produce a salt of the heteroaromatic structure-containing fluororesin film. Note that the hydrolysis treatment and acid treatment are the same as for general formula G1. When using this method, by controlling the reaction between the fluororesin G1 precursor and the modified compound, a film in which the heteroaromatic structure-containing fluororesin film and the fluororesin film are integrated can be made, resulting in a suitable film when it is desired to improve the adhesion between the heteroaromatic structure-containing fluororesin film and the fluororesin film. In addition, in the film obtained by this method, the distribution of the heteroaromatic structure-containing fluororesin within the film can also be controlled by controlling the reaction between the fluororesin precursor and the modified compound. To give a specific example, since the reaction proceeds from the point of contact between the fluororesin G1 precursor film and the modified compound, it is possible to create a film with a gradient in the concentration of the heteroaromatic structure-containing fluororesin from the point of contact.

[0148] The ion exchange membrane containing the heteroaromatic structure-containing fluororesin membrane of this embodiment, and the ion exchange membrane containing the heteroaromatic structure-containing fluororesin membrane and the fluororesin membrane (the ion exchange membrane is not particularly limited as long as it has two or more layers, and the same applies hereafter) can be used for various applications. Examples of such applications include redox flow batteries, fuel cells, sodium chloride electrolysis, alkaline water electrolysis, carbon dioxide reduction electrolysis, etc. Among these, redox flow battery cells and redox flow batteries are preferably exemplified. When used in redox flow battery cells and redox flow batteries, the power efficiency tends to be superior to conventionally used diaphragms.

[0149] The total thickness of the ion exchange membrane according to this embodiment is not particularly limited, but in the redox flow battery cell and redox flow battery exemplified as suitable applications, it is preferably 0.01 μm or more and 200 μm or less, as handling and mechanical strength of the membrane tend to improve. It is more preferably 1 μm or more, and especially preferably 20 μm or more, when membrane pulsation is large and high mechanical strength is required. As electrical resistance is suppressed when the redox flow battery cell and redox flow battery are in operation, and power efficiency tends to improve, it is more preferably 150 μm or less, even more preferably 130 μm or less, and especially preferably 100 μm or less.

[0150] In the ion exchange membrane according to this embodiment, the thickness of layer (L1) (fluororesin membrane containing a heteroaromatic structure) is not particularly limited, but in the redox flow battery cell and redox flow battery exemplified as suitable applications, it is preferably 0.001 μm or more and 10 μm or less. When used in a redox flow battery cell and a redox flow battery, the thickness of layer (L1) tends to further suppress the permeation of redox active substances through the membrane, so it is more preferably 0.01 μm or more, even more preferably 0.1 μm or more, and when the pulsation of the heteroaromatic structure-containing fluororesin membrane is large and high mechanical strength is required, it is particularly preferably 0.2 μm or more, and even more particularly preferably 0.3 μm or more. The thickness of the layer (L1) is more preferably 7 μm or less, even more preferably 5 μm or less, particularly preferably 3 μm or less, and even more preferably 1 μm or less, as this tends to suppress the electrical resistance of the redox flow battery cell and the redox flow battery when it is in operation, thereby improving power efficiency.

[0151] The equivalent weight of the ion exchange membrane according to this embodiment is not particularly limited, but is preferably 500 g / eq or more and 2000 g / eq or less, as this tends to improve the handling properties and mechanical strength of the membrane. It is more preferably 700 g / eq or more, even more preferably 800 g / eq or more, and especially preferably 880 g / eq or more, and even more preferably 900 g / eq or more, in cases where the membrane pulsation is large and high mechanical strength is required. The equivalent weight of the ion exchange membrane according to this embodiment is more preferably 1500 g / eq or less, even more preferably 1400 g / eq or less, especially preferably 1200 g / eq or less, and even more preferably 1150 g / eq or less, as this tends to suppress the electrical resistance when operating the redox flow battery cell and the redox flow battery, and improve power efficiency.

[0152] The ion exchange membrane of a second embodiment according to another embodiment comprises a layer (L3) containing a side-chain nitrogen atom-containing fluororesin having a structural unit represented by the following general formula A3, its saponide, or its salt, [ka] (In the formula, X 20 , X 21 , X 22 , and X 23 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 20 and X 21 , or X 20 and X 22 It may also form a ring structure. R 20 , and R 21 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. R 22 , and R 24 This is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 26 , and R 27 R is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, 26 , and R 27 This is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, with at least one being substituted or unsubstituted. R 23 , and R 25may be the same or different and each is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may be substituted or unsubstituted, or a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms which may be substituted or unsubstituted. When h is 2 or more, R is repeated 23 may be the same or different and each is X 24 is a divalent group represented by -CO2- or -SO2- a and g represent molar ratios in all constitutional units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1 b is an integer of 0 to 8 c is 0 or 1 d, e, f, and h may be the same or different and each is an integer of 0 to 6. However, d, e, and f are not simultaneously 0.) a layer (M3) containing a fluororesin (G1) having a structural unit represented by the following general formula G1

Chemical formula

[0153] <Side-chain nitrogen atom-containing fluororesin A3> The side-chain nitrogen atom-containing fluororesin A3 has a structural unit represented by the following general formula A3. In the following, the side-chain nitrogen atom-containing fluororesin having the structural unit represented by the above general formula A3 is also referred to as "side-chain nitrogen atom-containing fluororesin A3".

Chemical formula

[0154] ]](True]]X 20 、X 21 、X 22 、and X 23Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 20 and X 21 , or X 20 and X 22 It may form a ring structure. 20 , X 21 , X 22 , and X 23 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of side-chain nitrogen atom-containing fluororesins, fluorine atoms and unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability, such as the resistance to oxidation degradation of side-chain nitrogen atom-containing fluororesins, fluorine atoms and trifluoromethyl groups are more preferred, and fluorine atoms are particularly preferred.

[0155] R 20 , and R 21 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 20 , and R 21 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of side-chain nitrogen atom-containing fluororesins, fluorine atoms and unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability, such as the resistance to oxidation degradation of side-chain nitrogen atom-containing fluororesins, fluorine atoms and trifluoromethyl groups are more preferred, with fluorine atoms being particularly preferred.

[0156] R 22 , and R 24These may be the same or different, and are a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. 22 , and R 24 From the viewpoint of ease of obtaining raw materials and the tendency to suppress the manufacturing cost of side-chain nitrogen atom-containing fluororesins, hydrogen atoms and unsubstituted aliphatic hydrocarbon groups having 1 to 10 carbon atoms are preferred, hydrogen atoms and unsubstituted aliphatic hydrocarbon groups having 1 to 4 carbon atoms are more preferred, and from a similar viewpoint, R 24 A hydrogen atom is more preferably a hydrogen atom, an unsubstituted aliphatic hydrocarbon group having 1 to 2 carbon atoms is more preferably a hydrogen atom. 22 From the viewpoint of reducing the manufacturing cost of the side-chain nitrogen atom-containing fluororesin, hydrogen atoms are even more preferred, and from the viewpoint of improving the stability of the side-chain nitrogen atom-containing fluororesin under alkaline conditions, unsubstituted aliphatic hydrocarbon groups having 1 to 2 carbon atoms are even more preferred.

[0157] R 26 , and R 27 R is a hydrogen atom, or a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms. 26 , and R 27 Because at least one of the components is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, it tends to exhibit a good balance of current efficiency, voltage efficiency, and power efficiency when used in redox flow battery cells and redox flow batteries. From a similar perspective, R 26 , and R 27 It is more preferable that both are substituted or unsubstituted aliphatic hydrocarbon groups having 1 to 10 carbon atoms. 26 , and R 27 When used in redox flow battery cells and redox flow batteries, it tends to exhibit a good balance of current efficiency, voltage efficiency, and power efficiency. Therefore, it is preferable that it be an unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, more preferably an unsubstituted aliphatic hydrocarbon group having 1 to 6 carbon atoms, and even more preferably an unsubstituted aliphatic hydrocarbon group having 1 to 4 carbon atoms.

[0158] R 23, and R 25 These may be the same or different, and are substituted or unsubstituted divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms, or substituted or unsubstituted divalent aromatic hydrocarbon groups having 6 to 10 carbon atoms. Note that if h is 2 or more, the R is repeated. 23 They may be the same or different. 23 , R 25 From the viewpoint of ease of obtaining raw materials and the tendency to suppress the manufacturing cost of side-chain nitrogen atom-containing fluororesins, unsubstituted aliphatic hydrocarbon groups having 1 to 10 carbon atoms are preferred, unsubstituted aliphatic hydrocarbon groups having 2 to 6 carbon atoms are more preferred, unsubstituted aliphatic hydrocarbon groups having 2 to 4 carbon atoms are even more preferred, and unsubstituted aliphatic hydrocarbon groups having 2 to 3 carbon atoms are particularly preferred.

[0159] In the case of "substitution," the substituents are the same as those exemplified in General Formula 1.

[0160] X 24 This is a divalent group represented by the formulas -CO2- and -SO2-. From the viewpoint of improving the chemical stability, such as the resistance to oxidative degradation of side-chain nitrogen atom-containing fluororesins, the divalent group represented by the formula -SO2- is preferred.

[0161] In side-chain nitrogen atom-containing fluororesins, from the viewpoint of improving the chemical stability of the side-chain nitrogen atom-containing fluororesins, such as resistance to oxidative degradation, and from the viewpoint of suppressing the manufacturing cost of the side-chain nitrogen atom-containing fluororesins and thus suppressing the manufacturing cost of redox flow battery cells, it is preferable to include at least one selected from the group consisting of the structural unit represented by the following general formula A2, the structural unit represented by the following general formula A17, the structural unit represented by the following general formula A18, and the structural unit represented by the following general formula A19. -(CF2-CF2)-[A2] -(CF2-CF(-O-(CF2CFXO) N -Bg))- [A17] (In the formula, X represents F or a perfluoroalkyl group having 1 to 3 carbon atoms. Ag represents ((CF2) in the general formula A3 above) f -X24 -NR 22 -(R 23 -NR 24 ) h -R 25 -NR 26 R 27 ), which indicates that N is an integer from 0 to 5. -(CF2-CF(-O-(CF2) P -CFX(-O-(CF2) K -SO2NX 51 Bx)))- [A18] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms. X 51 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Bx is -(R in the general formula A3 above). 23 -NR 24 ) h -R 25 -NR 26 R 27 This shows that P is an integer between 0 and 12, and K is an integer between 1 and 5. However, P and K cannot be 0 simultaneously. -(CF2-CF(-O-(CF2) Q -CFX(-(CF2) L -O-(CF2) o -SO2NX 51 Bx)))- [A19] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms. X 41 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is -(R in the general formula A3 above). 23 -NR 24 ) h -R 25 -NR 26 R 27 This shows that Q represents an integer between 0 and 12, L represents an integer between 1 and 5, and o represents an integer between 0 and 6. However, Q and O cannot be 0 at the same time.

[0162] The fluororesin containing a side-chain nitrogen atom preferably comprises at least one selected from the group consisting of a structural unit represented by general formula A2, a structural unit represented by general formula A17, a structural unit represented by general formula A18, and a structural unit represented by general formula A19. From the same viewpoint, it is more preferable to contain a structural unit represented by general formula A2 and a structural unit represented by general formula A17 (where X is F or a trifluoromethyl group, n is an integer of 0 to 2, and m is an integer of 1 to 4). It is particularly preferable to contain a structural unit represented by general formula A2 and a structural unit represented by general formula A17 (where X is F or a trifluoromethyl group, n is 0 or 1, and m is an integer of 2 to 4).

[0163] The fluororesin containing a side-chain nitrogen atom more preferably has a structural unit represented by the following general formula A20, and further preferably has a structural unit represented by the following general formula A21. -[CF2CF2] a -[CF2-CF((-O-CF2-(CF(CF3))) b -O-(CF2)2-SO2NX 51 Bx)] g - [A20] (In the formula, X 51 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is -(R 23 -NR 24 ) h -R 25 -NR 26 R 27 ) shown in the above general formula A3. a and g represent the molar ratios in all the constitutional units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1. b is 0 or 1.) -[CF2CF2] a -[CF2-CF((-O-CF2-(CF(CF3)))-O-(CF2)2-SO2NX 51 Bx)] g - [A21] (In the formula, X 51is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is, in the above general formula A3, -(R 23 -NR 24 ) h -R 25 -NR 26 R 27 ). a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1.)

[0164] The method for producing the side-chain nitrogen atom-containing fluororesin is not particularly limited, but an example is a method of reacting the above-mentioned fluororesin G1 precursor with a modifying compound described later.) The modifying compound has at least two nitrogen atoms. Among the nitrogen atoms, the functional group containing the first nitrogen atom is a primary amino group or a secondary amino group. From the viewpoint of improving the reactivity between the modifying compound and the side-chain nitrogen atom-containing fluororesin precursor, it is preferably a primary amino group, and from the viewpoint of improving the stability of the side-chain nitrogen atom-containing fluororesin, it is preferably a secondary amino group. Among the at least two nitrogen atoms contained in the modifying compound, the functional group containing the second nitrogen atom is a secondary amino group, a tertiary amino group, and at least one functional group selected from the group consisting of the amino group and an acidic substance. In the reaction between the acidic fluororesin precursor and the modifying compound, when suppression of side reactions is required, a secondary amino group or a tertiary amino group is preferable, and a tertiary amino group is more preferable.)

[0165] Examples of modified compounds include N-methylethylenediamine, N-ethylethylenediamine, N,N-dimethylethylenediamine, N,N'-dimethylethylenediamine, N,N,N'-trimethylethylenediamine, N,N-diethylethylenediamine, N-benzylethylenediamine, N,N-dibutylethylenediamine, 1,2-diphenylethylenediamine, N,N-dicyclohexyl-1,2-ethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyldipropylenetriamine, and N,N-dibutylethylenediamine. Examples include tyldipropylenetriamine, N,N-diethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-diethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, N,N-dimethyl-1,4-cyclohexanediamine, 3-aminopiperidine, isophoronediamine, 4-(aminomethyl)piperidine, 3-aminopyrrolidine, 4-aminopiperidine, 3-aminopyrrolidine, N,N-dimethyltrimethylenediamine, and N,N-dibutyltrimethylenediamine. The modified compounds may be used individually or in combination of multiple compounds.

[0166] Among the modified compounds, N-methylethylenediamine, N-ethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyldipropylenetriamine, N,N-dibutyldipropylenetriamine, N,N-diethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-diethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, N,N-dimethyl-1,4-cyclohexanediamine, N,N-dimethyltrimethylenediamine, and N,N-dibutyltrimethylenediamine are more preferred because they are readily available and tend to reduce the manufacturing cost of ion exchange membranes for redox flow batteries containing side-chain nitrogen atom-containing fluororesins.

[0167] Among the modified compounds, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyldipropylenetriamine, N,N-dibutyldipropylenetriamine, N,N-dimethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, and N,N-dimethyltrimethylenediamine are particularly preferred because when an ion exchange membrane for redox flow batteries containing a side-chain nitrogen atom-containing fluororesin is used as a cell for redox flow batteries and as a diaphragm for redox flow batteries, it tends to exhibit a well-balanced and excellent current efficiency, voltage efficiency, and power efficiency.

[0168] From a similar viewpoint, N,N-dimethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyldipropylenetriamine, and N,N-dimethyltrimethylenediamine are particularly preferred.

[0169] The side-chain nitrogen atom-containing fluororesin in this embodiment has a sulfonamide bond (-SO2NR-) (wherein R is not particularly limited in the formula representing sulfonamide). The presence of a sulfonamide bond in a heteroaromatic structure-containing fluororesin can be analyzed by general analytical methods, and analytical instruments such as FT-IR and TOF-SIMS can be used.

[0170] The side-chain nitrogen atom-containing fluororesin in this embodiment may be its saponified form or a salt thereof.

[0171] The saponified product of the side-chain nitrogen atom-containing fluororesin is a saponified product obtained by reacting the side-chain nitrogen atom-containing fluororesin with an alkaline substance. Examples of basic substances include amine compounds such as dimethylamine, diethylamine, monomethylamine, and monoethylamine, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides. Among these, sodium hydroxide or potassium hydroxide is preferred.

[0172] Salts of side-chain nitrogen atom-containing fluororesins are salts of side-chain nitrogen atom-containing fluororesins with acidic substances. Examples of acidic substances include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as oxalic acid, acetic acid, formic acid, and trifluoroacetic acid.

[0173] <Fluororesin G1> The side-chain nitrogen atom-containing fluororesin in this embodiment may be used as a resin composition mixed with other resins. The resin composition may include the side-chain nitrogen atom-containing fluororesin and fluororesin G1 in this embodiment. In this embodiment, a mixture of fluororesins, such as a composition containing a side-chain nitrogen atom-containing fluororesin and fluororesin G1, is referred to as a fluororesin composition. Fluororesin G1 is a fluororesin that has ion exchange capacity for cations (hereinafter also referred to as "positive ions").

[0174] Fluororesin G1 has structural units represented by the following general formula G1. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) The preferred fluororesin G1 is as described above.

[0175] When using a side-chain nitrogen atom-containing fluororesin having a structural unit represented by general formula A3, the ratios of various resins are exemplified as follows. The weight ratio of the side-chain nitrogen atom-containing fluororesin to the fluororesin G1 in the resin composition is not particularly limited, but is preferably 1:100 to 100:1. Depending on the application of the resin composition according to this embodiment, when used as a diaphragm for a redox flow battery, the weight ratio of the side-chain nitrogen atom-containing fluororesin to the fluororesin G1 is preferably 5:95 or higher, more preferably 10:90 or higher, and even more preferably 15:85 or higher, from the viewpoint of suppressing the elution of the side-chain nitrogen atom-containing fluororesin into the electrolyte. Depending on the application of the mixture, when used as a diaphragm for a redox flow battery, the weight ratio of the side-chain nitrogen atom-containing fluororesin tends to improve power efficiency, so it is preferably 90:10 or lower, more preferably 70:30 or lower, and even more preferably 60:40 or lower.

[0176] The content of side-chain nitrogen atom-containing fluororesin in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Depending on the application in which the mixture is used, when used as a diaphragm for redox flow batteries, the power efficiency tends to be improved by the side-chain nitrogen atom-containing fluororesin, so the content of side-chain nitrogen atom-containing fluororesin in the resin composition is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0177] The resin composition according to this embodiment preferably comprises styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, polyether ether ketone resin, polysulfone resin, polyether sulfone resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, polyphenylene ether resin, polyphenylene sulfide resin, syndiotactic polystyrene resin, polyetherimide, siloxane-modified polyetherimide resin, polyamideimide resin, cycloolefin resin, cycloolefin copolymer, polyether ketone ether ketone ketone resin, polyallyl ether ketone resin, and fluororesin, and may further comprise styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, syndiotactic polystyrene resin, cycloolefin resin, and cycloolefin copolymer. The resins that may be included in the resin composition according to this embodiment may be used individually or in combination of multiple types.

[0178] <Ion exchange membrane> The ion exchange membrane according to this embodiment comprises a fluororesin containing side-chain nitrogen atoms, or a resin composition according to this embodiment.

[0179] When forming a resin composition containing a side-chain nitrogen atom-containing fluororesin into a film, the molding method is not particularly limited. Examples include a method in which the resin composition containing the side-chain nitrogen atom-containing fluororesin is in a molten state and processed into a film by extruding it using an extruder with a nozzle or die, or a method in which the resin composition containing the side-chain nitrogen atom-containing fluororesin is in a solution state and coated onto a substrate using a die, gravure roll, knife, or spray, and then dried to form a film. The resulting side-chain nitrogen atom-containing fluororesin film will also be referred to as a side-chain nitrogen atom-containing fluororesin film below.

[0180] The solvents that can be used when preparing a fluororesin containing side-chain nitrogen atoms in solution are not particularly limited and include, for example, saturated hydrocarbon compounds such as n-pentane, n-hexane, n-octane, n-decane, cyclopentane, cyclohexane, and cyclooctane; aromatic hydrocarbon compounds such as benzene, toluene, xylene, and ethylbenzene; halogenated hydrocarbon compounds such as methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, and dichlorobenzene; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, cyclohexanol, and benzyl alcohol; and ketones such as acetone, ethyl methyl ketone, methyl butyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples include: compounds; esters such as ethyl acetate, butyl acetate, and methyl benzoate; ethers such as diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, and dioxane; polyols such as ethylene glycol, propylene glycol, and glycerin, and polymers of compounds having two hydroxyl groups among the polyols; and esterified compounds of the polymers, nitriles such as acrylonitrile and benzonitrile; nitromethane; N,N-dimethylformamide; dimethyl sulfoxide; hexamethylphosphoric triamide; carbon disulfide; fluorinated compounds (e.g., Novec™ manufactured by 3M, Asahiclean manufactured by Asahi Glass Co., Ltd., etc.). The solvent may be used alone or in combination of multiple types.

[0181] When forming a film from a composition containing a side-chain nitrogen atom-containing fluororesin, a substrate can also be used. Using a substrate may allow for more stable production of the film from the side-chain nitrogen atom-containing fluororesin composition. The materials used as the base material are not particularly limited, and examples include polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, cycloolefin polymer, polycarbonate, polyamide, polyimide, polyamide-imide, polyvinyl chloride, polystyrene, polyphenylene ether, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide resin, polyether ketone, polyallyl ether ketone, etc. The materials used as the base material may be modified, and may be used individually or in combination of multiple materials.

[0182] The ion exchange membrane according to this embodiment comprises a layer (L3) containing the aforementioned side-chain nitrogen atom-containing fluororesin and a structural unit represented by the following general formula G1. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.) It has at least one alternating layer of fluororesin (M3) and .

[0183] By using a film containing fluororesin G1 (hereinafter also referred to as a fluororesin film) as the base material for layer (M3), an ion exchange membrane having a fluororesin film (M3) and a side-chain nitrogen atom-containing fluororesin film (L3) can be obtained. Note that layer (M3) does not necessarily have to contain a heteroaromatic structure-containing fluororesin. The ion exchange resin according to this embodiment may have one layer (L3) and one layer (M3) (an ion exchange membrane having one layer (L3) and one layer (M3) is also called a "bipolar membrane"). By forming a laminated membrane, an ion exchange membrane can be made that combines the respective properties of fluororesin G1 and heteroaromatic structure-containing fluororesin. In the following, when the membranes are laminated, the fluororesin membrane will also be called the fluororesin layer, and the side-chain nitrogen atom-containing fluororesin membrane will also be called the side-chain nitrogen atom-containing fluororesin layer.

[0184] Furthermore, the interface between the layer containing side-chain nitrogen atom-containing fluororesin (L3) in the ion membrane and the layer containing fluororesin having a structural unit represented by general formula G1 (M3) is measured by a time-of-flight secondary ion mass spectrometer. Referring to JIS K 0146:2002, the presence or absence of the interface is determined from the value at which the maximum signal intensity of NSO2 (m / z 78, two peaks are detected, but the lower mass peak is used) becomes 1 / 10. The region where the maximum signal intensity of the NSO2 peak is 1 / 10 or more is defined as layer (L), and the region where the maximum signal intensity of the NSO2 peak is less than 1 / 10 is defined as layer (M).

[0185] The method for manufacturing the fluororesin film is as described above.

[0186] As a method for forming a side-chain nitrogen atom-containing fluororesin into a film, a side-chain nitrogen atom-containing fluororesin film can be produced by reacting a fluororesin G1 precursor film with a modified compound and then subjecting it to hydrolysis. Furthermore, acid treatment can also be performed. In other words, hydrolysis treatment can produce a saponide of the heteroaromatic structure-containing fluororesin film, and further acid treatment can produce a salt of the heteroaromatic structure-containing fluororesin film. Note that the hydrolysis treatment and acid treatment are the same as those for general formula G1. When using this method, by controlling the reaction between the fluororesin G1 precursor and the modified compound, a film in which the side-chain nitrogen atom-containing fluororesin film and the fluororesin film are integrated can be made, resulting in a suitable film when it is desired to improve the adhesion between the side-chain nitrogen atom-containing fluororesin film and the fluororesin film. In addition, in the film obtained by this method, the distribution of side-chain nitrogen atom-containing fluororesin within the film can also be controlled by controlling the reaction between the fluororesin G1 precursor and the modified compound. To give a specific example, since the reaction proceeds from the point of contact between the fluororesin G1 precursor film and the modified compound, it is possible to create a film with a gradient in the concentration of the side-chain nitrogen atom-containing fluororesin from the point of contact.

[0187] The ion exchange membrane having a chain nitrogen atom-containing fluororesin of this embodiment, and the ion exchange membrane containing a side-chain nitrogen atom-containing fluororesin membrane and a fluororesin membrane (the ion exchange membrane is not particularly limited as long as it has two or more layers, and the same applies hereafter) can be used for various applications. Examples of such applications include redox flow batteries, fuel cells, sodium chloride electrolysis, alkaline water electrolysis, carbon dioxide reduction electrolysis, etc. Among these, redox flow battery cells and redox flow batteries are preferably exemplified. When used in redox flow battery cells and redox flow batteries, they tend to have superior power efficiency compared to conventionally used diaphragms.

[0188] The total thickness of the ion exchange membrane according to this embodiment is not particularly limited, but in the redox flow battery cell and redox flow battery exemplified as suitable applications, it is preferably 0.01 μm or more and 200 μm or less, as handling and mechanical strength of the membrane tend to improve. It is more preferably 1 μm or more, and especially preferably 20 μm or more, when membrane pulsation is large and high mechanical strength is required. As electrical resistance is suppressed when the redox flow battery cell and redox flow battery are in operation, and power efficiency tends to improve, it is more preferably 150 μm or less, even more preferably 130 μm or less, and especially preferably 100 μm or less.

[0189] In the ion exchange membrane according to this embodiment, the thickness of layer (L3) (side-chain nitrogen atom-containing fluororesin membrane) is not particularly limited, but in the redox flow battery cell and redox flow battery exemplified as suitable applications, it is preferably 0.001 μm or more and 10 μm or less. When used in a redox flow battery cell and a redox flow battery, the thickness of layer (L3) tends to further suppress the permeation of redox active substances through the membrane, so it is more preferably 0.003 μm or more, even more preferably 0.005 μm or more, and when the pulsation of the heteroaromatic structure-containing fluororesin membrane is large and high mechanical strength is required, it is particularly preferably 0.01 μm or more, and even more particularly preferably 0.04 μm or more. The thickness of the layer (L3) is more preferably 7 μm or less, even more preferably 5 μm or less, particularly preferably 3 μm or less, and even more preferably 1.5 μm or less, as this tends to suppress the electrical resistance of the redox flow battery cell and the redox flow battery when it is in operation, thereby improving power efficiency.

[0190] The equivalent weight of the ion exchange membrane according to this embodiment is not particularly limited, but is preferably 500 g / eq or more and 2000 g / eq or less, as this tends to improve the handling properties and mechanical strength of the membrane. It is more preferably 700 g / eq or more, even more preferably 800 g / eq or more, and especially preferably 880 g / eq or more, and even more preferably 900 g / eq or more, in cases where the membrane pulsation is large and high mechanical strength is required. The equivalent weight of the ion exchange membrane according to this embodiment is more preferably 1500 g / eq or less, even more preferably 1400 g / eq or less, especially preferably 1200 g / eq or less, and even more preferably 1150 g / eq or less, as this tends to suppress the electrical resistance when operating the redox flow battery cell and the redox flow battery, and improve power efficiency.

[0191] <Cells for redox flow batteries> A redox flow battery cell, exemplified as a suitable application for the ion exchange membrane of this embodiment, comprises a first electrolyte containing a first redox active material, a second electrolyte containing a second redox active material, a first electrode in contact with the first electrolyte, a second electrode in contact with the second electrolyte, and a diaphragm disposed between the first and second electrolytes. It should be noted that elements other than those commonly used by those skilled in the art, as well as elements known from publicly available documents and patents relating to redox flow battery cells, may also be included. Examples of such elements include bipolar plates, frames, compressible seals, conductive additives, and balancing cells.

[0192] Figure 1 shows an example of a schematic diagram of the redox flow battery cell. The redox flow battery cell 10 has an electrolytic cell 6 which includes a cell chamber 2 containing an electrode 1 (positive electrode in Figure 1) consisting of a first electrode, a cell chamber 4 containing an electrode 3 (negative electrode in Figure 1) consisting of a second electrode, and a diaphragm 5 which separates the cell chamber 2 and the cell chamber 4. The cell chambers 2 and 4 contain an electrolyte containing redox active material. The electrolyte containing redox active material is stored, for example, in an electrolyte tank 7 and a tank 8, and supplied to each cell chamber by a pump or the like. The current generated by the redox flow battery cell may be converted from DC to AC via an AC / DC converter 9, or converted from AC to DC via an AC / DC converter 9 to fill the redox flow battery cell. The redox flow battery cell of this embodiment is preferably a redox flow secondary battery cell.

[0193] <Redox flow battery> A redox flow battery can be formed by stacking the aforementioned redox flow battery cells. When stacking, electrical current can be supplied between each redox flow battery cell via a bipolar plate. The material of the bipolar plate is not particularly limited, and examples include carbon, graphite, and metal. Furthermore, the material may contain dispersed carbon particles, carbon fibers, metal particles, metal fibers, graphene, and carbon nanotubes. It can be used individually or in combination with other types. Bipolar plates may have various flow paths to improve contact between the electrodes and the electrolyte. The flow paths are not particularly limited, and examples include serpentine, interdigitated, parallel, multi-parallel, discontinuous, and combinations thereof.

[0194] <Electrolyte> The electrolyte in this embodiment is a liquid containing a redox active material and a solvent. A redox active material is a substance that has redox activity that directly contributes to the electromotive force in a redox flow battery cell. The redox active material used in this embodiment is not particularly limited, but examples include metallic redox active materials, nonmetallic redox active materials, and organic redox active materials, and all of them may be neutral compounds or ionic compounds. A metallic redox active material is a substance containing at least one metal atom, which may contain multiple metal atoms of the same type or multiple metal atoms of different types. The metal atoms used in the metallic redox active material are not particularly limited, but examples include aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, lead, and cerium. Among these, titanium, vanadium, chromium, manganese, iron, and cerium are preferred. Furthermore, from the viewpoint of using the same type of metal for both the first and second redox active materials, vanadium, iron, copper, and tin are preferred, vanadium and iron are more preferred, and vanadium is particularly preferred. Metallic redox active materials may have commonly used active material ligands, and examples of ligands include cyanide ions, acetylacetone, ethylenediamine, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, carbon monoxide, bipyridine, bipyrazine, ethylene glycol, propylene glycol, ethanedithiol, butanedithiol, terpyridine, diethylenetriamine, triazacyclononane, tris(hydroxymethyl)aminomethane, ascorbic acid, citric acid, glycolic acid, gluconic acid, acetic acid, formic acid, benzoic acid, malic acid, maleic acid, phthalic acid, sarcosinic acid, salicylic acid, oxalic acid, urea, aminophenolate, and lactic acid. The active material ligand may be a single type or a combination of multiple types. The substances used as nonmetallic redox active materials are not particularly limited, but examples include chlorine, bromine, sulfur, and polysulfide. Examples of organic redox active materials include, but are not limited to, viologens, their derivatives, and compounds having a viologen structure in the polymer side chain; 2,2,6,6-tetramethyl-1-piperidinyloxy radicals, their derivatives, and compounds having a 2,2,6,6-tetramethyl-1-piperidinyloxy radical structure in the polymer side chain; ferrocene, its derivatives, and compounds having a ferrocene structure in the polymer side chain; quinones, their derivatives, and compounds having a quinone structure in the polymer side chain; anthraquinones, their derivatives, and compounds having anthraquinone structure in the polymer side chain; quinoxalines, their derivatives, and compounds having a quinoxaline structure in the polymer side chain. The redox active material may be a single type or a combination of multiple types.

[0195] When using the aforementioned redox active material in a cell for a redox flow battery, the redox active material used in the electrolyte of the positive electrode and the redox active material used in the electrolyte of the negative electrode can be used in combination according to the desired properties. The combination of redox active materials is not particularly limited, but examples include vanadium / vanadium, iron / iron, lead / lead, copper / copper, iron / chromium, chromium / bromine, zinc / bromine, polysulfide / bromine, zinc / cerium, zinc / nickel, zinc / cerium, zinc / iodine, titanium / manganese, vanadium / cerium, and vanadium / manganese. Among these, vanadium / vanadium, iron / iron, iron / chromium, chromium / bromine, zinc / bromine, and titanium / manganese are preferred because they provide high electromotive force and excellent stability during charging and discharging, vanadium / vanadium, iron / iron, and zinc / bromine are more preferred, and vanadium / vanadium is particularly preferred. When the redox active material for both the positive and negative electrodes is vanadium, it is also referred to as a vanadium redox flow battery cell or a vanadium redox flow battery. Furthermore, when the redox active material for both the positive and negative electrodes is vanadium, the positive electrode contains VO2. 2+ / VO2 + At the negative electrode, V 2+ / V 3+ Charging and discharging are performed by utilizing a redox couple and an oxidation-reduction reaction. During charging, the oxidation-reduction reaction results in an excess of protons (H+) in the positive electrode cell chamber and a deficiency of protons (H+) in the negative electrode cell chamber. The diaphragm selectively moves the excess protons from the positive electrode cell chamber to the negative electrode chamber, maintaining electrical neutrality. During discharging, the reverse reaction proceeds, maintaining electrical neutrality.

[0196] The solvent used in the electrolyte is not particularly limited, but examples include water, alcohols, nitriles, esters, ketones, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, etc. Among these, water is preferred from the viewpoint of improving safety when operating the redox flow battery cell. Specific examples of the aforementioned solvents include alcohols such as methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, diethylene glycol, and glycerol; nitriles such as acetonitrile, propionitrile, and benzonitrile; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as diethyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether; aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, octane, chloroform, dichloromethane, and tetrachloromethane; and aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, phenol, and cresol. The solvent used in the electrolyte may be a single solvent or a combination of multiple solvents.

[0197] The electrolyte may also contain an electrolyte. This electrolyte is a substance that dissociates into ions in the electrolyte and improves the electrical conductivity of the electrolyte. The electrolyte is not particularly limited, but examples include sulfuric acid, hydrochloric acid, nitric acid, acetic acid, phosphoric acid, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sodium acetate. The electrolyte used in the electrolyte solution may be a single type or a combination of multiple types.

[0198] Additives may be added to the electrolyte depending on the desired properties of the electrolyte. Examples of additives, though not particularly limited, include ethylene glycol, diethylene glycol, polyethylene glycol, glycerol, mannitol, sorbitol, pentaerythritol, tris(hydroxymethyl)aminomethane, corn starch, corn syrup, gelatin, glycerol, guar gum, pectin, and surfactants. The additives used in the electrolyte may be a single type or a combination of multiple types.

[0199] <Electrode> The electrodes in this embodiment are not particularly limited. Examples of electrodes include metal electrodes and carbon electrodes. The material of the metal electrode is not particularly limited, but examples include aluminum, gold, silver, copper, chromium, molybdenum, nickel, thallium, titanium, iridium, zinc, tin, and composites of the aforementioned metals. The shape of the metal electrode is not particularly limited, but examples include plate-shaped, lattice-shaped, mesh-shaped (rhomboid, tortoise-shell-shaped), wire-shaped, and rod-shaped. Carbon electrodes are not particularly limited, but examples include glassy carbon electrodes, pyrolysis carbon electrodes, carbon felt electrodes, carbon paper electrodes, carbon foam electrodes, carbon cloth electrodes, carbon knit electrodes, carbon nanofiber sheet electrodes, and activated carbon fiber sheet electrodes. In applications where liquids or gases are circulated inside the electrode, it is preferable that the electrode has continuous voids, and more preferably that it is a porous body having continuous voids. Examples of carbon electrodes having continuous voids include carbon felt electrodes, carbon paper electrodes, carbon foam electrodes, carbon cloth electrodes, carbon knit electrodes, carbon nanofiber sheet electrodes, and activated carbon fiber sheet electrodes. Among these, carbon felt, carbon paper, and carbon foam are preferred from the viewpoint of high flexibility and large surface area, which can reduce resistance, and carbon foam is more preferred. In carbon foam, it is preferable that the carbon portion has a three-dimensionally continuous structure. In carbon foam, it is preferable that it has linear portions and connecting portions that connect the linear portions, as this allows for high flexibility and a large surface area. Specific examples of carbon felt and carbon paper include SIGRACELL® KFD series, GFA series, GFD series, SGL series, and SIGRACET® series from SGL CARBON, carbon felt from Toyobo Co., Ltd. (e.g., XF30A, BW-309), CARBORON® GF series from Nippon Carbon Co., Ltd. (e.g., GF-20, GF-3F), TORAYCA® TGP series from Toray Industries, Inc., PYROFIL® series and GRAFIL® series from Mitsubishi Chemicals Corporation, VGCF® sheets from Showa Denko K.K., carbon felt from MERSEN, and graphite felt. These may be subjected to activation treatments such as oxidation as needed. Carbon foam can be manufactured by known methods (International Patent Application Publication No. 2018 / 096895, International Patent Application Publication No. 2018 / 168741, International Patent Application Publication No. 2020 / 045645). The electrodes may be used individually or in combination of multiple types.

[0200] <Membrane electrode assembly> The membrane electrode assembly in this embodiment has a structure in which an ion exchange membrane (hereinafter, the ion exchange membrane is also referred to as the assembly membrane) and at least one electrode are joined together. This joining means that the assembly membrane and at least one electrode are connected, and by joining, the assembly membrane and at least one electrode can be integrated. For example, in a diaphragm electrode assembly comprising an assembly membrane and two electrodes, when assembling a redox flow battery cell, the process of sequentially assembling the electrode, the assembly membrane, and the electrode becomes unnecessary, and it can be reduced to a single process, which tends to reduce manufacturing costs, and is therefore sometimes preferred. The method for joining the bonding film to at least one electrode is not particularly limited, but examples include methods using a hot press and / or a hot roll press. The bonding temperature is not particularly limited, but it is preferable to set it to room temperature or higher, as insufficient bonding between the bonding film and the electrode tends to reduce the elastic modulus of the bonding film and improve the bonding between the bonding film and the electrode. The bonding temperature is preferably 250°C or lower, more preferably 200°C or lower, even more preferably 170°C or lower, and particularly preferably 150°C or lower, as this tends to suppress deterioration of the bonding film. The pressure used during bonding is not particularly limited, but is greater than 0 MPa. Since bonding between the bonding film and the electrode tends to improve, it is preferably 0.01 MPa or higher, more preferably 0.05 MPa or higher, even more preferably 0.08 MPa or higher, and particularly preferably 0.1 MPa or higher. Since electrode deterioration tends to be suppressed, it is preferably 100 MPa or lower, more preferably 50 MPa or lower, even more preferably 20 MPa or lower, and particularly preferably 10 MPa or lower. The bonding time is not particularly limited, but is greater than 0 seconds. Since bonding between the bonding film and the electrode tends to improve, it is preferably 0.01 seconds or more, more preferably 0.1 seconds or more, even more preferably 0.5 seconds or more, and particularly preferably 1 second or more. Since the cost of manufacturing the film electrode bonding body tends to be reduced, it is preferably 10 hours or less, more preferably 5 hours or less, even more preferably 2 hours or less, and particularly preferably 1 hour or less. The atmosphere used during bonding is not particularly limited, but examples include air, nitrogen, and argon. Air and nitrogen are preferred, and air is more preferred, as they tend to reduce the cost of manufacturing the film electrode assembly.

[0201] The membrane electrode assembly of this embodiment can be used for various applications, but is preferably exemplified by its use in redox flow battery cells and redox flow batteries. When used in redox flow battery cells and redox flow batteries, it tends to have superior power efficiency compared to conventionally used combinations of membrane and electrodes.

[0202] In the redox flow battery cell of this embodiment, when a side-chain heteroaromatic resin film, a heteroaromatic structure-containing fluororesin film, and a side-chain nitrogen atom-containing fluororesin film are used as the diaphragm, if a good balance of current efficiency and voltage efficiency and high power efficiency are desired, it is preferable that the side-chain heteroaromatic resin layer, the heteroaromatic structure-containing fluororesin film, and the side-chain nitrogen atom-containing fluororesin film be arranged on the electrode side that acts as the negative electrode, and preferably in the vicinity of the electrode. Proximal means that the distance between the side-chain heteroaromatic resin layer, the heteroaromatic structure-containing fluororesin film, and the side-chain nitrogen atom-containing fluororesin film and the electrode acting as the negative electrode is smaller than the distance between them and the electrode acting as the positive electrode. The reason why the aforementioned special effect is obtained by placing the side-chain heteroaromatic resin layer, the heteroaromatic structure-containing fluororesin film, and the side-chain nitrogen atom-containing fluororesin film proximal to the electrode side acting as the negative electrode is not entirely clear. However, it is presumed that the amount of redox active material moving from the positive electrode to the negative electrode is different from the amount moving from the negative electrode to the positive electrode, and that the side-chain heteroaromatic resin layer, the heteroaromatic structure-containing fluororesin layer, and the side-chain nitrogen atom-containing fluororesin layer functioned more effectively with respect to the redox active material that moved in greater quantities. Furthermore, when higher current efficiency is desired, it is preferable to place the side-chain heteroaromatic resin layer on both sides of the diaphragm.

[0203] By using the redox flow battery cell and redox flow battery of this embodiment, it is possible to provide a mechanism that smooths the supply and demand of power and stabilizes fluctuating power obtained from renewable energy sources such as solar and wind energy. More specifically, it is possible to provide integration of power obtained from renewable energy sources, power peak load shifting, stabilization of transmission and distribution networks, base load power, energy arbitrage, support for weak transmission and distribution networks, frequency regulation, and any combination of the above. It can also be used as a power source for remote camps, forward operating bases, power transmission and distribution telecommunications, remote sensors, etc., that do not utilize transmission and distribution networks. The redox flow battery cell and the redox flow battery of this embodiment may be equipped with a control system and a power adjustment unit. The control system allows for the control of various valves, pumps, circulation circuits, sensors, mitigation devices, other electronic / hardware control devices, and safety protection devices. By using a power adjustment unit, the voltage and current of the input power can be converted to a format optimized for redox flow battery cells and / or redox flow batteries, and the voltage and current of the output power can be converted to a format optimized for any application. For example, when redox flow battery cells and / or redox flow batteries are connected to a power grid, in the charging cycle, the power adjustment unit can convert the input AC power to DC power of a suitable voltage and current. In the discharge cycle, the redox flow battery cells and / or redox flow batteries generate DC power, and the power adjustment unit can convert this DC power to AC power of a voltage and frequency suitable for transmission to the power grid.

[0204] [Third Embodiment] Next, a third embodiment will be described.

[0205] Patent Document 1 discloses the alternating stacking of cation exchange base layers and anion exchange base layers to improve initial power efficiency, but the thickness of the cation exchange base layers and anion exchange base layers is not shown except in the examples. Furthermore, although a preferred range for the ion exchange capacity of an ion exchange membrane composed of an ion exchange layer having ion exchange groups and a porous support layer not having ion exchange groups is disclosed, the reasons why this range is preferred and examples demonstrating its preference are not described. In addition, the examples do not show the ion exchange capacity of the copolymer having structural formula (1) in Patent Document 1. Furthermore, although it is disclosed that the cation exchange base layer in the ion exchange base layer can be arranged on the positive electrode liquid side, thereby increasing the lifespan of the ion exchange base layer, nothing is shown regarding the arrangement of the anion exchange base layer.

[0206] Patent Document 2 discloses modifying Nafion® 117 with a heterocyclic molecule containing multiple nitrogen atoms. However, because Nafion® 117 has a large film thickness, even if it has the same proton area resistivity, when actually used in a redox flow battery, a lower proton area resistivity is required. Although it is also disclosed that a thin film can be made using a support, the proton area resistivity is higher than that of Nafion® 117, and when actually used in a redox flow battery, a lower proton area resistivity is required, as mentioned above. Furthermore, nothing is shown regarding the operation of a redox flow battery using the disclosed film. In addition, although it is disclosed that the side to which the heterocyclic molecule containing multiple nitrogen atoms is bound can be arbitrarily located near the negative half-cell of the battery in order to improve the performance of the film, it is not stated what performance is improved, nor is it shown in the examples. Furthermore, nothing is shown regarding the thickness of the heterocyclic molecule containing multiple nitrogen atoms within the film.

[0207] Patent Document 3 discloses the provision of a crossover prevention layer, which is a metal layer formed by reducing a cationic metal inside a polymer electrolyte membrane, in order to improve at least one of the characteristics of discharge capacity, current efficiency, voltage efficiency, and power efficiency. However, there is a need for even higher characteristics. Furthermore, it has been shown that the preferred range for the thickness of the formed metal layer is relatively large, between 10 μm and 50 μm. Nothing has been indicated regarding the preferred range for the equivalent weight (EW) of the polymer electrolyte membrane. Regarding the position of the crossover prevention layer inside the polymer electrolyte membrane, it has been shown that it is located between 10% and 90% of the thickness of the electrolyte membrane from the surface of the polymer electrolyte membrane. However, nothing has been indicated regarding whether the crossover prevention layer faces the positive electrode or the negative electrode when used as a flow battery.

[0208] Patent Document 4 discloses that, in order to suppress curling, the value obtained by dividing the thickness of the first ion exchange resin layer by the thickness of the second ion exchange resin layer should be between 0.7 and 1.3, indicating that the thicknesses of the first and second ion exchange resin layers are equal, that is, the anion exchange resin layer is located in the center of the thickness direction of the entire film. Furthermore, even if the thicknesses of the first and second ion exchange resin layers are not the same, it is not indicated whether the anion exchange resin layer is located on the positive or negative side within the redox flow battery cell.

[0209] The object of this embodiment relates to a redox battery cell having high power efficiency, a redox flow battery, and a method for manufacturing a diaphragm.

[0210] As a result of diligent research into the above-mentioned problems, the inventors have found that when a diaphragm constituting a redox flow battery cell comprises at least a first cation-exchangeable resin layer and an anion-exchangeable resin layer, and the anion-exchangeable resin layer is located on the electrode side acting as the negative electrode, surprisingly, a higher power efficiency can be obtained compared to when the anion-exchangeable resin layer is located on the electrode side acting as the positive electrode. Furthermore, they have found that particularly high power efficiency can be obtained by setting the equivalent weight of the diaphragm and the thickness of the anion-exchangeable resin layer within a specific range.

[0211] The redox flow battery cell according to this embodiment is A first electrolyte containing a first redox active material, A second electrolyte containing a second redox active material, The first electrode in contact with the first electrolyte, The second electrode in contact with the second electrolyte, A diaphragm is placed between the first electrolyte and the second electrolyte, Includes, The aforementioned diaphragm, A first cation-exchangeable resin layer, Anion-exchangeable resin layer, It has at least the following features: The equivalent weight of the diaphragm is 1150 g / eq or less. The thickness of the anion-exchangeable resin layer is 0.001 μm or more and less than 5 μm. The anion-exchangeable resin layer of the diaphragm is positioned on the electrode side that acts as the negative electrode. According to this embodiment, it is possible to provide a redox battery cell with high power efficiency, a redox flow battery, and a method for manufacturing a diaphragm.

[0212] <Cells for redox flow batteries> The redox flow battery cell of this embodiment comprises a first electrolyte containing a first redox active material, a second electrolyte containing a second redox active material, a first electrode in contact with the first electrolyte, a second electrode in contact with the second electrolyte, and a diaphragm disposed between the first and second electrolytes. It should be noted that the cell may also include elements other than those commonly used by those skilled in the art, as well as elements known from publicly available documents and patents relating to redox flow battery cells. Examples of such elements include a bipolar plate, a frame, a compressible seal, a conductive additive, and a balancing cell.

[0213] Figure 1 shows an example of a schematic diagram of a redox flow battery cell of this embodiment. The redox flow battery cell 10 of this embodiment has an electrolytic cell 6 which includes a cell chamber 2 containing an electrode 1 (positive electrode in Figure 1) consisting of a first electrode, a cell chamber 4 containing an electrode 3 (negative electrode in Figure 1) consisting of a second electrode, and a diaphragm 5 which separates the cell chamber 2 and the cell chamber 4. The cell chambers 2 and 4 contain an electrolyte containing redox active material. The electrolyte containing redox active material is stored, for example, in an electrolyte tank 7 and a tank 8, and supplied to each cell chamber by a pump or the like. The current generated by the redox flow battery cell may be converted from DC to AC via an AC / DC converter 9, or converted from AC to DC via an AC / DC converter 9 to fill the redox flow battery cell. The redox flow battery cell of this embodiment is preferably a redox flow secondary battery cell.

[0214] <Electrolyte> The electrolyte in this embodiment is a liquid containing a redox active material and a solvent. A redox active material is a substance that has redox activity that directly contributes to the electromotive force in a redox flow battery cell. The redox active material used in this embodiment is not particularly limited, but examples include metallic redox active materials, nonmetallic redox active materials, and organic redox active materials, and all of them may be neutral compounds or ionic compounds.

[0215] A metallic redox active material is a substance containing at least one metal atom, which may contain multiple metal atoms of the same type or multiple metal atoms of different types. The metal atoms used in the metallic redox active material are not particularly limited, but examples include aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, lead, and cerium. Among these, titanium, vanadium, chromium, manganese, iron, and cerium are preferred. Furthermore, from the viewpoint of using the same type of metal for both the first and second redox active materials, vanadium, iron, copper, and tin are preferred, vanadium and iron are more preferred, and vanadium is particularly preferred.

[0216] Metallic redox active materials may have commonly used active material ligands, and examples of ligands include cyanide ions, acetylacetone, ethylenediamine, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, carbon monoxide, bipyridine, bipyrazine, ethylene glycol, propylene glycol, ethanedithiol, butanedithiol, terpyridine, diethylenetriamine, triazacyclononane, tris(hydroxymethyl)aminomethane, ascorbic acid, citric acid, glycolic acid, gluconic acid, acetic acid, formic acid, benzoic acid, malic acid, maleic acid, phthalic acid, sarcosinic acid, salicylic acid, oxalic acid, urea, aminophenolate, and lactic acid. The active material ligand may be a single type or a combination of multiple types.

[0217] The substances used as nonmetallic redox active materials are not particularly limited, but examples include chlorine, bromine, sulfur, and polysulfide.

[0218] Examples of organic redox active materials include, but are not limited to, viologen, its derivatives, and compounds having a viologen structure in the polymer side chain; 2,2,6,6-tetramethyl-1-piperidinyloxy radical, its derivatives, and compounds having a 2,2,6,6-tetramethyl-1-piperidinyloxy radical structure in the polymer side chain; ferrocene, its derivatives, and compounds having a ferrocene structure in the polymer side chain; quinone, its derivatives, and compounds having a quinone structure in the polymer side chain; anthraquinone, its derivatives, and compounds having an anthraquinone structure in the polymer side chain; quinoxaline, its derivatives, and compounds having a quinoxaline structure in the polymer side chain. The redox active material may be used alone or in combination of multiple types.

[0219] When using the aforementioned redox active material in a cell for a redox flow battery, the redox active material used in the electrolyte of the positive electrode and the redox active material used in the electrolyte of the negative electrode can be used in combination according to the desired properties. The combination of redox active materials is not particularly limited, but examples include vanadium / vanadium, iron / iron, lead / lead, copper / copper, iron / chromium, chromium / bromine, zinc / bromine, polysulfide / bromine, zinc / cerium, zinc / nickel, zinc / cerium, zinc / iodine, titanium / manganese, vanadium / cerium, and vanadium / manganese. Among these, vanadium / vanadium, iron / iron, iron / chromium, chromium / bromine, zinc / bromine, and titanium / manganese are preferred because they provide high electromotive force and excellent stability during charging and discharging, vanadium / vanadium, iron / iron, and zinc / bromine are more preferred, and vanadium / vanadium is particularly preferred.

[0220] When the redox active material for both the positive and negative electrodes is vanadium, it is also referred to as a vanadium redox flow battery cell or a vanadium redox flow battery. Furthermore, when the redox active material for both the positive and negative electrodes is vanadium, the positive electrode contains VO2. 2+ / VO2 + At the negative electrode, V 2+ / V 3+Charging and discharging are performed by utilizing a redox couple and an oxidation-reduction reaction. During charging, the oxidation-reduction reaction results in an excess of protons (H+) in the positive electrode cell chamber and a deficiency of protons (H+) in the negative electrode cell chamber. The diaphragm selectively moves the excess protons from the positive electrode cell chamber to the negative electrode chamber, maintaining electrical neutrality. During discharging, the reverse reaction proceeds, maintaining electrical neutrality.

[0221] The solvent used in the electrolyte is not particularly limited, but examples include water, alcohols, nitriles, esters, ketones, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, etc. Among these, water is preferred from the viewpoint of improving safety when operating the redox flow battery cell. Specific examples of the aforementioned solvents include alcohols such as methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, diethylene glycol, and glycerol; nitriles such as acetonitrile, propionitrile, and benzonitrile; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as diethyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether; aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, octane, chloroform, dichloromethane, and tetrachloromethane; and aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, phenol, and cresol. The solvent used in the electrolyte may be a single solvent or a combination of multiple solvents.

[0222] The electrolyte may also contain an electrolyte. This electrolyte is a substance that dissociates into ions in the electrolyte and improves the electrical conductivity of the electrolyte. The electrolyte is not particularly limited, but examples include sulfuric acid, hydrochloric acid, nitric acid, acetic acid, phosphoric acid, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sodium acetate. The electrolyte used in the electrolyte solution may be a single type or a combination of multiple types.

[0223] Additives may be added to the electrolyte depending on the desired properties of the electrolyte. Examples of additives, though not particularly limited, include ethylene glycol, diethylene glycol, polyethylene glycol, glycerol, mannitol, sorbitol, pentaerythritol, tris(hydroxymethyl)aminomethane, corn starch, corn syrup, gelatin, glycerol, guar gum, pectin, and surfactants. The additives used in the electrolyte may be a single type or a combination of multiple types.

[0224] <Electrode> The electrodes used in the redox flow battery cell of this embodiment are not particularly limited, but carbon electrodes are preferred. The carbon electrodes preferably have continuous voids to allow the electrolyte to pass through, and more preferably are porous materials having continuous voids. Examples of carbon electrodes having continuous voids include carbon felt, carbon paper, carbon foam, carbon cloth, carbon knit, carbon nanofiber sheets, activated carbon fiber sheets, etc., with carbon felt, carbon paper, and carbon foam being preferred. Among these, carbon foam is preferred from the viewpoint of high flexibility and a large surface area that can reduce resistance. The carbon foam preferably has a three-dimensionally continuous carbon structure. The carbon foam preferably has linear portions and connecting portions that join the linear portions, as high power efficiency can be obtained due to its high flexibility and large surface area.

[0225] Specific examples of carbon felt and carbon paper include SIGRACELL® KFD series, GFA series, GFD series, SGL series, and SIGRACET® series from SGL CARBON, carbon felt from Toyobo Co., Ltd. (e.g., XF30A, BW-309), CARBORON® GF series from Nippon Carbon Co., Ltd. (e.g., GF-20, GF-3F), TORAYCA® TGP series from Toray Industries, Inc., PYROFIL® series and GRAFIL® series from Mitsubishi Chemicals Corporation, VGCF® sheets from Showa Denko K.K., carbon felt from MERSEN, and graphite felt. These may be subjected to activation treatments such as oxidation as needed.

[0226] Carbon foam can be manufactured by known methods (International Patent Application Publication No. 2018 / 096895, International Patent Application Publication No. 2018 / 168741, International Patent Application Publication No. 2020 / 045645).

[0227] The first electrode and the second electrode may be single electrodes or different electrodes, and within the first electrode and / or the second electrode, single electrodes or a combination of multiple electrodes may be used.

[0228] <diaphragm> In this embodiment, the diaphragm is a membrane disposed between a first electrolyte and a second electrolyte, and comprises at least a first cation-exchangeable resin layer and an anion-exchangeable resin layer, the equivalent weight of the diaphragm is 1150 g / eq or less, the thickness of the anion-exchangeable resin layer is 0.001 μm or more and less than 5 μm, and in a redox flow battery cell, the anion-exchangeable resin layer of the diaphragm is disposed on the electrode side that acts as the negative electrode.

[0229] The equivalent weight of the diaphragm is not particularly limited, but is preferably 1150 g / eq or less, and more preferably 1100 g / eq or less, as it tends to reduce proton transfer resistance and improve power efficiency. It is more preferably 1050 g / eq or less, particularly preferably 1030 g / eq or less, and even more preferably 1000 g / eq or less, as it tends to improve the hydrophilicity of the diaphragm. It is preferably 500 g / eq or more, and more preferably 700 g / eq or more, as it tends to improve the solubility of the diaphragm in the electrolyte. It is even more preferably 800 g / eq or more, and particularly preferably 880 g / eq or more, as it tends to improve the mechanical strength of the diaphragm against electrolyte pulsation and contact with electrodes.

[0230] In this embodiment, equivalent weight refers to the dry mass in grams of ion-exchangeable resin per equivalent of ion-exchangeable groups in an ion-exchangeable resin, which is a resin having ion-exchangeability. In the case of the first cation-exchangeable resin layer, it refers to the dry mass in grams of the first cation-exchangeable resin layer per equivalent of ion-exchangeable groups in the first cation-exchangeable resin layer. Hereafter, the expression "equivalent weight" will be used as appropriate. In addition, in measuring the equivalent weight, a method can be used in which the ion-exchangeable resin is substituted with salt and the solution is back-titrated with an alkaline solution. The equivalent weight can be appropriately adjusted by the copolymerization ratio of the monomers that are the raw materials of the cation-exchangeable resin, the selection of monomer species, etc.

[0231] In this embodiment, the anion-exchangeable resin layer contained in the diaphragm is preferably positioned on the electrode side acting as the negative electrode, and preferably proximal to the electrode. Proximal means that the distance of the anion-exchangeable resin layer to the electrode acting as the negative electrode is smaller than the distance to the electrode acting as the positive electrode. In this application, the inventors have found that, surprisingly, power efficiency is improved by positioning the anion-exchangeable resin layer on the electrode side acting as the negative electrode. The reason for the improvement in power efficiency is not clear, but it is presumed that the amount of redox active material moving from the positive electrode to the negative electrode is different from the amount of redox active material moving from the negative electrode to the positive electrode, and the anion-exchangeable resin layer functioned more effectively on the redox active material that moved in larger quantities. Furthermore, since positioning the anion-exchangeable resin layer on the electrode side acting as the negative electrode had an effect, it is presumed that it effectively acted on the amount of redox active material moving from the negative electrode to the positive electrode.

[0232] The distance D between the anion-exchange resin layer of the diaphragm and the electrode acting as the negative electrode. neg The distance D between the anion-exchangeable resin layer of the diaphragm and the electrode acting as the positive electrode. pos It is preferable that the following relationship is observed. D neg / D pos <1 Here, distance D neg This refers to the distance from the nearest contact surface of the anion-exchange resin layer to the negative electrode to the nearest-nearest surface of the negative electrode. Distance D pos This refers to the distance from the nearest-nearest surface of the anion-exchange resin layer to the positive electrode to the nearest-nearest surface of the positive electrode. D neg / D pos From the viewpoint of further improving power efficiency, it is preferably 0.8 or less, more preferably 0.7 or less, even more preferably 0.6 or less, and even more preferably 0.5 or less. neg / D pos The lower limit of this value is not particularly limited, but it may be, for example, 0 or greater. In other words, the anion-exchangeable resin layer and the negative electrode may be in contact.

[0233] From the viewpoint of further improving power efficiency, the first cation-exchangeable resin layer is preferably positioned closer to the electrode side acting as the positive electrode than the anion-exchangeable resin layer.

[0234] <First cation-exchangeable resin layer> The first cation-exchangeable resin layer is a layer formed of a substance containing a resin that has ion exchange ability for cations (hereinafter also referred to as "cation-exchangeable resin").

[0235] The cation exchange resin is not particularly limited, but examples include hydrocarbon resins and fluororesins. From the viewpoint of suppressing the manufacturing cost of redox flow battery cells, hydrocarbon resins are preferred, and from the viewpoint of improving the durability of redox flow battery cells, fluororesins are preferred.

[0236] Hydrocarbon resins and fluororesins may be used individually or in combination.

[0237] The functional groups with ion exchange ability contained in cation exchange resins are not particularly limited, but include sulfo groups (SO3H), carboxyl groups (CO2H), phenolic hydroxyl groups (OH), phosphate groups (PO3H2), thiol groups (SH), and the hydrogen atoms of these functional groups being alkali metals, alkaline earth metals, transition metals, etc. Functional groups with ion exchange ability may be used individually or in combination of multiple functional groups.

[0238] Among functional groups with ion exchange capacity, sulfo groups, carboxyl groups, and / or phosphate groups are preferred, sulfo groups and / or carboxyl groups are more preferred, and sulfo groups are particularly preferred, as they tend to exhibit superior ion exchange capacity.

[0239] The hydrocarbon resin is not particularly limited, but examples include polystyrene, polyphenylene ether, polybenzimidazole, polyetheretherketone, polyimide, polyetherimide, polyaryletherketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylsulfone, etc., and is a resin having a functional group having the ion exchange ability. Depending on the required physical properties, the resin may be crosslinked or a copolymer, and may have various substituents (for example, halogen atoms such as fluorine, chlorine, and bromine atoms; aliphatic hydrocarbon groups such as nitrile groups, methyl groups, ethyl groups, vinyl groups, allyl groups, 1-methylvinyl groups, n-propyl groups, iso-propyl groups, n-butyl groups, iso-butyl groups, sec-butyl groups, tert-butyl groups, etc.; aromatic hydrocarbon groups such as benzyl groups, phenyl groups, and nitrile-substituted phenyl groups; amino groups; nitro groups; hydroxyl groups; silyl groups, etc.). Hydrocarbon resins may be used individually or in combination of multiple types.

[0240] The fluororesins are not particularly limited, but examples include partially fluorinated resins and fully fluorinated resins having the ion-exchange functional groups described above. Resins in which at least one hydrogen atom, though not all, of the hydrogen atoms on the carbon contained in the hydrocarbon-based cation-exchange resin is replaced with a fluorine atom, and resins in which all the hydrogen atoms on the carbon are replaced with fluorine, are exemplified as partially fluorinated resins and fully fluorinated resins.

[0241] As for the fluororesin, a fluororesin having a structural unit represented by general formula G1 (hereinafter also referred to as "fluororesin G1") is preferred from the viewpoint of improving the durability of redox flow battery cells. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.)

[0242] The equivalent weight of the first cation-exchangeable resin layer is not particularly limited, but is preferably less than 1100 g / eq and more preferably 1050 g / eq or less, as this tends to reduce proton transfer resistance and improve power efficiency. Furthermore, it is more preferably 1030 g / eq or less and particularly preferably 1000 g / eq or less, as this tends to improve the hydrophilicity of the first cation-exchangeable resin layer. It is preferably 500 g / eq or more and more preferably 700 g / eq or more, as this tends to improve solubility in the electrolyte. Furthermore, it is even more preferably 800 g / eq or more and particularly preferably 880 g / eq or more, as this tends to improve mechanical strength against electrolyte pulsation and contact with electrodes.

[0243] The thickness of the first cation-exchangeable resin layer is not particularly limited, but is preferably 1 μm or more and 150 μm or less. Since proton transfer resistance tends to be reduced and power efficiency tends to be improved, it is more preferably 100 μm or less, even more preferably 80 μm or less, and particularly preferably 60 μm or less. Since mechanical strength against electrolyte pulsation and contact with electrodes tends to be improved, it is more preferably 5 μm or more, even more preferably 10 μm or more, particularly preferably 20 μm or more, and even more particularly preferably 25 μm or more.

[0244] The content of the cation exchange resin in the first ion exchange resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit to the content of the cation exchange resin, but it is preferably 100% by mass or less in the first ion exchange resin layer. It is more preferably 99.5% by mass or less, and even more preferably 99% by mass or less, as this tends to reduce the cost of removing substances other than the cation exchange resin in the first ion exchange resin layer and thus reduce the cost of the cell for redox flow batteries.

[0245] The method for producing the first cation-exchangeable resin layer used in the diaphragm of this embodiment is not particularly limited, and can be obtained by processing a cation-exchangeable resin into a film, or by processing a cation-exchangeable resin precursor having functional groups with ion-exchange ability into a film by hydrolysis, and then performing the aforementioned hydrolysis treatment and acid treatment. For example, one method is to process the cation-exchangeable resin into a film by melt-kneading it and then extruding it using an extruder with a nozzle or die. Another method is to melt-knead the cation-exchangeable resin precursor, form a film by extruding it using an extruder with a nozzle or die, and then perform hydrolysis treatment and acid treatment to form ion-exchange groups. Alternatively, the cation-exchangeable resin may be dispersed in a solvent and then processed into a film by casting it onto a substrate.

[0246] The method for producing fluororesin G1 is as described above.

[0247] <Anion exchange resin layer> An anion-exchangeable resin layer is a layer containing an anion-exchangeable compound. An anion-exchangeable compound is a compound having a nitrogen-containing functional group and molecular structure, such as a primary amino group, secondary amino group, tertiary amino group, quaternary ammonium group, pyridine ring structure and its derivative structure, pyridinium group, imidazole ring structure and its derivative structure, imidazolium group, pyrrole ring structure and its derivative structure, and is a compound that is positively charged under at least acidic conditions.

[0248] The diaphragm of this embodiment has an anion-exchangeable resin layer, which imparts electrostatic repulsion to cations in the electrolyte to the diaphragm, suppressing the permeation of redox active material with high charge density through the diaphragm while allowing protons with low charge density to permeate through the diaphragm, thereby improving power efficiency.

[0249] Anion-exchangeable compounds are not particularly limited and include, for example, polyvinylpyridine polymers and their salts, vinylpyridine / divinylbenzene copolymers and their salts, vinylpyridine / styrene copolymers and their salts, polyethyleneimine and its salts, vinylbenzyltrimethylammonium chloride polymers, polyvinylimidazole polymers and their salts, vinylimidazole / divinylbenzene copolymers and their salts, vinylimidazole / styrene copolymers and their salts, polyvinylpyrrolidone polymers and their salts, polybenzimidazole and its salts, polymers having a benzimidazole structure and their salts, polypyrrole and its salts, polyaniline, poly(4-aminostyrene) and its salts, poly(vinylcarbazole) and its salts, anion-exchangeable polymers such as tetrabutylammonium and octyltrimethylammonium, quaternary ammonium compounds having a quaternary ammonium group, pyridinium compounds having a pyridinium structure, such as butylpyridinium, and their derivatives, trimethylamine and its salts, triethylamine and its salts, tributyl Amines and their salts, triethanolamine and its salts, pyrrole and its salts, pyrrole derivatives and their salts, 1,8-diazabicyclo[5.4.0]undecene-7 and its salts, 1,5-diazabicyclo[4.3.0]nonene-5 and its salts, 1,4-diazabicyclo[2.2.2]octane and its salts, 1-azabicyclo[2.2.2.]octane and its salts, N,N,N',N'-tetramethylbutanediamine and its salts, ethylenediamine, N,N-dimethylethylenediamine, N-methylethylenediamine, Examples include N,N-dibutylethylenediamine, N,N-dimethyldipropylenetriamine, 1-(3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, 4-aminopyridine, 1,2,3-triaminobenzene, hexamethylenetetramine, imidazole, oxazole, thiazole, pyrazole, aminobenzimidazole, 4-aminopiperidine, tetrafluoro-p-phenylenediamine, hexamethylenediamine, 4,4'-diaminodiphenyl ether, and 4-benzylpyridine.

[0250] The anion-exchange compound may be an anion-exchange fluororesin represented by the following general formula B17, its saponide, or its salt. -[CFX 1 CX 2 X 3 ] a -[CF2-CF((-O-CF2-(CF(CF2X 4 ))) b -O c -(CFR 1 ) d -(CFR 2 ) e -(CF2) f -Ae)] g - [B17] (In the formula, X 1 , X 2 , X 3 and X 4 These may be the same or different, and consist of a halogen atom and a perfluoroalkyl group having 1 to 10 carbon atoms, which may be substituted or unsubstituted, or a cyclic perfluoroalkyl group, wherein the halogen atom may be a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 1 and X 2 , or X 1 and X 3 It may also be a ring structure. 1 , R 2 These may be the same or different, and consist of a hydrogen atom, a halogen atom, a perfluoroalkyl group having 1 to 10 carbon atoms (which may be substituted or unsubstituted), and a fluorochloroalkyl group, wherein the halogen atom may be a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Ae is -CONX 6 Ax, -SO2NX 6 Ax is a monovalent base represented by the formula Ax, and X 6is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may be substituted or unsubstituted, or an aromatic hydrocarbon group, and Ax is an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may be substituted or unsubstituted and contains at least one nitrogen atom, an aromatic hydrocarbon group, or a heteroaromatic group. a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1. b is an integer from 0 to 8. c is 0 or 1. d, e, and f may be the same or different and are integers from 0 to 6 (however, when d, e, and f are simultaneously 0, Ae is -CF(CF2Az)2 and Az is -CONX 6 Ax, -SO2NX 6 is a monovalent group represented by the formula of Ax, and Ax and X 6 are the same as described above.) The anion-exchangeable compound may be used alone or in combination of a plurality of kinds.

[0251] In addition, the substituent in the case of "substituted" is the same as the substituent exemplified in General Formula 1.

[0252] As anion-exchange compounds, their dissolution in the electrolyte is suppressed, and the durability of redox flow battery cells tends to improve. Therefore, polyvinylpyridine polymers and their salts, vinylpyridine / divinylbenzene copolymers and their salts, vinylpyridine / styrene copolymers and their salts, polyethyleneimine and its salts, vinylbenzyltrimethylammonium chloride polymers, polyvinylimidazole polymers and their salts, vinylimidazole / divinylbenzene copolymers and their salts, vinylimidazole / styrene copolymers and their salts, polyvinylpyrrolidone polymers and their salts, polybenzimidazole and its salts, polymers having a benzimidazole structure and their salts, polypyrrole and its salts, polyaniline, poly(4-aminostyrene) and its salts, It is preferable that the compound is at least one anion-exchange compound selected from the group consisting of li(vinylcarbazole) and its salts, anion-exchange fluororesins represented by general formula B17 and their saponifies or salts thereof, and more preferably that the compound is at least one anion-exchange compound selected from the group consisting of polyvinylpyridine polymers and their salts, vinylpyridine / divinylbenzene copolymers and their salts, vinylpyridine / styrene copolymers and their salts, polyvinylimidazole polymers and their salts, vinylimidazole / divinylbenzene copolymers and their salts, vinylimidazole / styrene copolymers and their salts, polybenzimidazole and its salts, polymers having a benzimidazole structure and their salts, and anion-exchange fluororesins represented by general formula B17.Since the electrostatic repulsive force to the cations of the anion-exchangeable resin layer increases, and the power efficiency of the redox flow battery cell tends to improve, it is more preferable that the compound is at least one anion-exchangeable compound selected from the group consisting of polyvinylpyridine polymers and their salts, polyvinylimidazole polymers and their salts, polybenzimidazole and its salts, polymers having a benzimidazole structure and their salts, and anion-exchangeable fluororesins represented by general formula B17. It is particularly preferable that the compound is at least one anion-exchangeable compound selected from the group consisting of polyvinylpyridine polymers and their salts, polyvinylimidazole polymers and their salts, and anion-exchangeable fluororesins represented by general formula B17.

[0253] The saponified product of the anion-exchange fluororesin represented by general formula B17 is a saponified product obtained by the reaction of the anion-exchange fluororesin with an alkaline substance. Examples of basic substances include amine compounds such as dimethylamine, diethylamine, monomethylamine, and monoethylamine, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides. Among these, sodium hydroxide or potassium hydroxide is preferred.

[0254] Salts of anion-exchangeable fluororesins are salts of anion-exchangeable fluororesins with acidic substances. Examples of acidic substances include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as oxalic acid, acetic acid, formic acid, and trifluoroacetic acid.

[0255] In an anion-exchange fluororesin represented by the above general formula B17 that can be used in anion-exchange compounds, it is preferable that the anion-exchange fluororesin contains at least one selected from the group consisting of the following general formula B16, the following general formula B18, the following general formula B19, and the following general formula B20, from the viewpoint of improving the chemical stability such as the resistance to oxidation degradation of the anion-exchange fluororesin, and from the viewpoint of suppressing the manufacturing cost of the anion-exchange fluororesin and suppressing the manufacturing cost of redox flow battery cells. -(CF2-CF2)- [B16] -(CF2-CF(-O-(CF2CFXO) N -Ag))- [B18] (In the formula, X represents F or a perfluoroalkyl group having 1 to 3 carbon atoms. Ag represents (CF2) M -SO2NX 6 Ax(X 6 Ax is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group, or a heteroaromatic group containing at least one nitrogen atom. N represents an integer from 0 to 5. M represents an integer from 0 to 6. However, N and M cannot be 0 at the same time. -(CF2-CF(-O-(CF2) P -CFX(-O-(CF2) K -SO2NX 6 Ax)))- [B19] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms. X 6P is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group. Ax is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group, or a heteroaromatic group containing at least one nitrogen atom. P represents an integer from 0 to 12, and K represents an integer from 1 to 5. However, P and K cannot be 0 simultaneously. -(CF2-CF(-O-(CF2) Q -CFX(-(CF2) L -O-(CF2) o -SO2NX 6 Ax)))- [B20] (In the formula, X represents a perfluoroalkyl group having 1 to 3 carbon atoms. X 6 Q is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group. Ax is a substituted or unsubstituted aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a heteroaromatic group having 1 to 20 carbon atoms, containing at least one nitrogen atom. Q represents an integer from 0 to 12, L represents an integer from 1 to 5, and o represents an integer from 0 to 6. However, Q and O cannot be 0 at the same time. The anion-exchangeable fluororesin is more preferably composed of a structural unit represented by general formula B16, and at least one selected from the group consisting of a structural unit represented by general formula B18, a structural unit represented by general formula B19, and a structural unit represented by general formula B20. From a similar viewpoint, it is even more preferably to contain a structural unit represented by general formula B16 and a structural unit represented by general formula B18 (wherein X is F or a trifluoromethyl group, n is an integer from 0 to 2, and m is an integer from 1 to 4), and it is particularly preferably to contain a structural unit represented by general formula B16 and a structural unit represented by general formula B18 (wherein X is F or a trifluoromethyl group, n is 0 or 1, and m is an integer from 2 to 4).

[0256] The anionic exchange fluororesin preferably has a structural unit represented by the following general formula B21, and more preferably has a structural unit represented by the following general formula B22. -[CF2CF2] a -[CF2-CF((-O-CF2-(CF(CF3))) b -O-(CF2)2-SO2NX 6 Ax)] g - [B21] (In the formula, X 6 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, and Ax is a substituted or unsubstituted aliphatic hydrocarbon group, aromatic hydrocarbon group, or heteroaromatic group having 1 to 20 carbon atoms, which contains at least one nitrogen atom. a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0≦a<1, 0<g≦1, and a + g = 1. b is 0 or 1.) -[CF2CF2] a -[CF2-CF((-O-CF2-(CF(CF3)))-O-(CF2)2-SO2NX 6 Ax)] g - [B22] (In the formula, X 6 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group, and Ax is a substituted or unsubstituted aliphatic hydrocarbon group, aromatic hydrocarbon group, or heteroaromatic group having 1 to 20 carbon atoms, which contains at least one nitrogen atom. a and g represent the molar ratios in all the constituent units contained in the resin, and are numbers satisfying 0≦a<1, 0<g≦1, and a + g = 1.)

[0257] In the above general formulas B17 to B22, since the production of the anionic exchange fluororesin becomes simple and the production cost of the cell for the redox flow battery can be suppressed, X 6Preferably, it is a hydrogen atom, a substituted, or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms. From the viewpoint of reducing the manufacturing cost of the anion-exchange fluororesin, a hydrogen atom is more preferable, and from the viewpoint of improving the stability of the anion-exchange fluororesin under alkaline conditions, an unsubstituted aliphatic hydrocarbon group having 1 to 2 carbon atoms is even more preferable.

[0258] In the above general formulas B17 to B22, since the cost of raw materials tends to be reduced and the manufacturing cost of redox flow battery cells can be suppressed, Ax is preferably an unsubstituted aliphatic hydrocarbon group, aromatic hydrocarbon group, or heteroaromatic group having 1 to 20 carbon atoms and containing at least one nitrogen atom, and more preferably an unsubstituted aliphatic hydrocarbon group or heteroaromatic group having 1 to 10 carbon atoms and containing at least one nitrogen atom. More specifically, preferred structures of nitrogen atoms contained in Ax include primary amino groups, secondary amino groups, tertiary amino groups, pyridine ring structures and their derivative structures, pyridinium groups, imidazole ring structures and their derivative structures, imidazolium groups, pyrrole ring structures and their derivative structures, and more preferably tertiary amino groups, pyridine ring structures and their derivative structures, imidazole ring structures and their derivative structures.

[0259] The method for producing an anion-exchangeable fluororesin is not particularly limited, but an example is a method in which a fluororesin precursor is reacted with an anion-exchangeable compound other than the anion-exchangeable fluororesin (hereinafter also referred to as a "modified compound").

[0260] The modified compound has at least two nitrogen atom-containing groups, and The nitrogen atom-containing group is Primary amino group, Secondary amino group, tertiary amino group, An amino salt structure is a reaction product of at least one amino group selected from the group consisting of primary amino groups, secondary amino groups, and tertiary amino groups, and at least one substance selected from the group consisting of acidic substances and halogen atom-containing aliphatic hydrocarbon compounds. nitrogen atom-containing heterocyclic structure, A nitrogen-containing heterocyclic salt structure is a reaction product of a nitrogen-containing heterocyclic structure with at least one substance selected from the group consisting of acidic substances and halogen atom-containing aliphatic hydrocarbon compounds, and Quaternary ammonium group, Examples of modified compounds include at least one selected from the group consisting of the above. Among these, it is preferable that at least one nitrogen atom-containing group is a primary amino group or a secondary amino group, and more preferably a primary amino group, as this tends to improve reactivity with fluororesin precursors. However, the quaternary ammonium group is a quaternary ammonium group different from the amino salt structure or the salt structure.

[0261] To give more specific examples of modified compounds, consider ethylenediamine, N-methylethylenediamine, N-ethylethylenediamine, N,N-dimethylethylenediamine, N,N'-dimethylethylenediamine, N,N,N'-trimethylethylenediamine, N-benzylethylenediamine, N,N-dibutylethylenediamine, 1,2-diphenylethylenediamine, N,N'-dicyclohexyl-1,2-ethylenediamine, N,N-dimethyl-1,3-propanediamine, N, N-dimethyldipropylenetriamine, N,N-dibutyldipropylenetriamine, N,N-diethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-diethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, N,N-dimethyl-1,4-cyclohexanediamine, 3-aminopiperidine, isophoronediamine, 4-(aminomethyl)piperidine, 3-aminopyrrolidine, 4-aminopiperidine, 3-aminopyrrol Lysine, N,N-dimethyltrimethylenediamine, N,N-dibutyltrimethylenediamine, 1-(3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, isonicotinamide, 4-(ethylaminomethyl)pyridine, 4-(4-piperidyl)pyridine, 2-methyltryptamine, 5-methoxytryptamine, 6-methoxytryptamine, necrostatin-1, alosetron, sulfamethoxypyridazine, 1-(3-chloroanilinol Examples include )-4-phenylphthalazine, 4-amino-5-aminomethyl-2-methylpyrimidine, 2-(aminomethyl)-5-methylpyrazine, 2-(4-piperidinyl)benzimidazole, 2-(4-aminophenyl)benzimidazole, 5-amino-2-(4-aminophenyl)benzimidazole, 6-(aminomethyl)quinoline, 2-methyl-7-[phenyl(phenylamino)methyl]-8-quinolinol, and 1-(2-amino-1-naphthyl)isoquinoline. Modified compounds may be used individually or in combination of multiple compounds.

[0262] Modified compounds include ethylenediamine, N-methylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyldipropylenetriamine, N,N-dibutyldipropylenetriamine, N,N-dimethyl-1,4-butanediamine, and N,N-dimethyl-1,6-hexanediamine, as these are readily available raw materials and tend to reduce the manufacturing costs of anion-exchange fluororesins. Preferably, N,N-dimethyltrimethylenediamine, N,N-dibutyltrimethylenediamine, 1-(3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, isonicotinamide, 4-(ethylaminomethyl)pyridine, 4-(2-aminoethyl)pyridine, 4-(4-piperidyl)pyridine, 2-(4-piperidinyl)benzimidazole, 2-(4-aminophenyl)benzimidazole, and 5-amino-2-(4-aminophenyl)benzimidazole are used in redox flow electrophoresis. When used in battery cells and redox flow batteries, it tends to have a good balance of current efficiency, voltage efficiency and power efficiency, therefore, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyldipropylenetriamine, N,N-dibutyldipropylenetriamine, N,N-dimethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, N,N-dimethyltrimethylenediamine, 1-( 3-aminopropyl)imidazole, 4-(2-aminoethyl)pyridine, 4-picolylamine, isonicotinamide, 4-(4-piperidyl)pyridine, and 2-(4-aminophenyl)benzimidazole are more preferred, and from a similar viewpoint, N,N-dimethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyldipropylenetriamine, N,N-dimethyltrimethylenediamine, 1-(3-aminopropyl)imidazole, 4-picolylamine, and 4-(2-aminoethyl)pyridine are even more preferred.

[0263] The anion-exchangeable resin layer is preferably made of styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, polyether ether ketone resin, polysulfone resin, polyether sulfone resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, polyphenylene ether resin, polyphenylene sulfide resin, syndiotactic polystyrene resin, polyetherimide, siloxane-modified polyetherimide resin, polyamideimide resin, cycloolefin resin, cycloolefin copolymer, polyether ketone ether ketone ketone resin, polyallyl ether ketone resin, or fluororesin, and may further contain styrene resin, vinyl chloride resin, chlorinated polyethylene, polyamide resin, polyphenylene ether / polystyrene resin, high-density polyethylene resin, low-density polyethylene resin, linear low-density polyethylene resin, syndiotactic polystyrene resin, cycloolefin resin, cycloolefin copolymer, and the fluororesin represented by the general formula G1 described above. The resins that may be included in the anion-exchangeable resin layer may be used individually or in combination of multiple types.

[0264] From the viewpoint of improving the durability of redox flow battery cells, fluororesin is preferred.

[0265] The content of the anion-exchangeable compound in the anion-exchangeable resin layer is not particularly limited, but from the viewpoint of increasing the tendency to suppress the permeation of redox active material through the membrane, it is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit to the content of the anion-exchangeable compound in the anion-exchangeable resin layer, but it is preferably 100% by mass or less. If it becomes easier to obtain and the cost of forming the anion-exchangeable resin layer is reduced, it is more preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99% by mass or less.

[0266] When the anion-exchangeable resin layer contains an anion-exchangeable compound and a fluororesin, the content of the anion-exchangeable compound in the anion-exchangeable resin layer is not particularly limited, but from the viewpoint of increasing the tendency to suppress the permeation of redox active material through the membrane, it is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more. From the viewpoint of improving the durability of the anion-exchangeable resin layer, it is preferably 99% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0267] The thickness of the anion-exchangeable resin layer is 0.001 μm or more and less than 5 μm. Since proton transfer resistance tends to be reduced and power efficiency tends to be improved, a thickness of 4 μm or less is preferred, 3 μm or less is more preferred, and 1.5 μm or less is even more preferred. Since the permeation of redox active material through the membrane is suppressed and power efficiency tends to be improved, a thickness of 0.01 μm or more is preferred, 0.02 μm or more is more preferred, and 0.04 μm or more is even more preferred. Since the mechanical strength against electrolyte pulsation and contact with electrodes tends to be improved, a thickness of 0.1 μm or more is even more preferred, 0.3 μm or more is even more preferred, and 0.4 μm or more is even more preferred.

[0268] A method for manufacturing a diaphragm comprising at least a first cation-exchangeable resin layer and an anion-exchangeable resin layer according to this embodiment can be carried out by a process including the steps of forming the first cation-exchangeable resin layer and forming the anion-exchangeable resin layer. The method for producing the diaphragm of this embodiment involves a fluororesin precursor layer containing at least one selected from the group consisting of halogenated sulfonyl groups, acyl halide groups, and halogenated phosphoric acid groups, which serves as a precursor to the first cation-exchangeable resin layer, It has at least two nitrogen atom-containing groups, and the nitrogen atom-containing groups are Primary amino group, Secondary amino group, tertiary amino group, An amino salt structure is a reaction product of at least one amino group selected from the group consisting of primary amino groups, secondary amino groups, and tertiary amino groups, and at least one substance selected from the group consisting of acidic substances and halogen atom-containing aliphatic hydrocarbon compounds. nitrogen atom-containing heterocyclic structure, A nitrogen-containing heterocyclic salt structure is a reaction product of a nitrogen-containing heterocyclic structure with at least one substance selected from the group consisting of acidic substances and halogen atom-containing aliphatic hydrocarbon compounds, and Quaternary ammonium group, A modified compound comprising at least one selected from the group consisting of, The process of reacting and Preferably, after the above step, the process includes a step of converting at least one selected from the group consisting of halogenated sulfonyl groups, acyl halide groups, and halogenated phosphoric acid groups contained in the fluororesin precursor layer to at least one selected from the group consisting of sulfo groups, carboxyl groups, and phosphoric acid groups. However, the quaternary ammonium group is a quaternary ammonium group different from the amino salt structure and the salt structure. The fluororesin precursor layer is a layer that serves as a precursor to the first cation-exchangeable resin layer, and contains at least one selected from the group consisting of halogenated sulfonyl groups, acyl halide groups, and halogenated phosphoric acid groups.

[0269] The method for producing an anion-exchangeable resin layer is not particularly limited, and includes methods such as processing an anion-exchangeable compound or a mixture containing an anion-exchangeable compound into a film by extruding it using an extruder with a nozzle or die, or processing an anion-exchangeable compound or a mixture containing an anion-exchangeable compound into a film by coating it onto a substrate with a die, gravure roll, knife or spray, and drying it, while the anion-exchangeable compound or the mixture containing an anion-exchangeable compound is in a solution state.

[0270] A diaphragm can be manufactured by forming an anion-exchangeable resin layer and then laminating the anion-exchangeable resin layer with a first cation-exchangeable resin layer. The lamination method is not particularly limited, but examples include lamination by hot pressing and / or hot roll pressing.

[0271] A diaphragm can also be manufactured by melting and kneading the fluororesin precursor, processing it into a film by extruding it using an extruder with a nozzle or die, contacting it with a mixture containing a modified compound to form a layer containing an anion-exchangeable fluororesin, and then hydrolyzing it to obtain a fluororesin, thereby forming a layer containing a fluororesin that will become the first cation-exchangeable resin layer and a layer containing an anion-exchangeable fluororesin that will become the anion-exchangeable resin layer.

[0272] When manufacturing the diaphragm, a substrate can also be used. Using a substrate may allow for more stable manufacturing of the first cation-exchangeable resin layer and / or anion-exchangeable resin layer.

[0273] The material used for the base material is not particularly limited, and examples include polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, cycloolefin polymer, polycarbonate, polyamide, polyimide, polyamide-imide, polyvinyl chloride, polystyrene, polyphenylene ether, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide resin, polyether ketone, ether ketone, polyallyl ether ketone, and the like. The aforementioned substances may be modified as needed, and may be used individually or in combination of multiple substances.

[0274] The solvent used to prepare a mixture containing anion-exchangeable compounds into a solution is not particularly limited and includes, for example, saturated hydrocarbon compounds such as n-pentane, n-hexane, n-octane, n-decane, cyclopentane, cyclohexane, and cyclooctane; aromatic hydrocarbon compounds such as benzene, toluene, xylene, and ethylbenzene; halogenated hydrocarbon compounds such as methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, and dichlorobenzene; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, cyclohexanol, and benzyl alcohol; acetone, ethyl methyl ketone, methyl butyl ketone, methyl isobutyl ketone, and cyclohexanol. Examples include ketones such as ethanol; esters such as ethyl acetate, butyl acetate, and methyl benzoate; ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, methyltetrahydrofuran, and dioxane; polyols such as ethylene glycol, propylene glycol, and glycerin, and polymers of compounds having two hydroxyl groups among the polyols; and esterified compounds of the polymers, nitriles such as acrylonitrile and benzonitrile; nitromethane; N,N-dimethylformamide; dimethyl sulfoxide; hexamethylphosphoric triamide; carbon disulfide; fluorinated compounds (e.g., Novec™ manufactured by 3M, Asahiclean manufactured by Asahi Glass Co., Ltd., etc.) and the like. These solvents may be used individually or in combination.

[0275] <Second cation-exchangeable resin layer> The diaphragm of this embodiment may further comprise a second cation-exchangeable resin layer. In the diaphragm, the second cation-exchangeable resin layer may comprise a first cation-exchangeable resin layer, an anion-exchangeable resin layer, and a second cation-exchangeable resin layer in this order.

[0276] In a diaphragm using a second cation-exchangeable resin layer, the thickness of the first cation-exchangeable resin layer is greater than the thickness of the second cation-exchangeable resin layer. The thickness of the second cation-exchangeable resin layer is not particularly limited as long as it is smaller than the thickness of the first cation-exchangeable layer, but it is preferably 0.01 μm or more and less than 150 μm. Since proton transfer resistance tends to be reduced and power efficiency tends to be improved, it is more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 20 μm or less. Since the mechanical strength against electrolyte pulsation and contact with electrodes tends to be improved, it is more preferably 0.1 μm or more, even more preferably 0.5 μm or more, and particularly preferably 1 μm or more.

[0277] The value obtained by dividing the thickness of the second ion-exchangeable resin layer by the thickness of the first cation-exchangeable resin layer is not particularly limited, but is preferably less than 0.7. Since the anion-exchangeable resin layer can be positioned more proximal to the electrode side that acts as the negative electrode, the permeation of redox active material through the membrane tends to be suppressed and power efficiency tends to be improved, it is more preferably 0.6 or less, and even more preferably 0.5 or less. The value obtained by dividing the thickness of the second ion-exchangeable resin layer by the thickness of the first cation-exchangeable resin layer may be greater than 0, but is preferably 0.0001 or more from the viewpoint of making the manufacturing of the second ion-exchangeable resin layer easier. Since the mechanical strength against electrolyte pulsation and contact with the electrode tends to be improved, it is more preferably 0.001 or more, and particularly preferably 0.01 or more.

[0278] The second cation-exchangeable resin layer is a layer formed from a substance containing a cation-exchangeable resin, similar to the first cation-exchangeable resin layer. The cation-exchangeable resin used in the second cation-exchangeable resin layer is not particularly limited, but the cation-exchangeable resin preferably used is the same as that used in the first cation-exchangeable resin layer. From the viewpoint of improving the durability of the redox flow battery cell, it is more preferable for the second cation-exchangeable resin layer to contain a fluorine-based cation-exchangeable resin. The cation exchange resin contained in the first cation exchange resin layer and the cation exchange resin contained in the second cation exchange resin layer may be the same or different.

[0279] The method for manufacturing a diaphragm comprising a first cation-exchangeable resin layer, an anion-exchangeable resin layer, and a second cation-exchangeable resin layer is not particularly limited, but examples include: a method in which a cation-exchangeable resin that will become the second cation-exchangeable resin layer is melt-kneaded onto a two-layer film comprising a first cation-exchangeable resin layer and an anion-exchangeable resin layer, and then processed into a film by extrusion molding using an extruder with a nozzle or die; a method in which a cation-exchangeable resin precursor that will become the second cation-exchangeable resin layer is melt-kneaded, processed into a film by extrusion molding using an extruder with a nozzle or die, and then subjected to the aforementioned hydrolysis treatment and acid treatment to form ion-exchange groups; and a method in which a cation-exchangeable resin that will become the second cation-exchangeable resin layer is dispersed in a solvent and then processed into a film by casting. Furthermore, a two-layer film comprising two types of cation-exchangeable resin layers and an anion-exchangeable resin layer can also be manufactured by overlapping the anion-exchangeable resin layers simultaneously. When overlapping the anion-exchange resin layers, a hot press and / or a hot roll press can be used, as this tends to reduce delamination between the layers.

[0280] The diaphragm of this embodiment may also use a support. The support is not particularly limited and examples include supports made of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, cycloolefin polymer, polyamide, polyimide, polyamide-imide, polyvinyl chloride, polystyrene, polyphenylene ether, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide resin, polyether ketone, polyallyl ether ketone, fluororesin, etc. Since voids may form between the cation exchange resin layer or the anion exchange resin layer and the support, potentially reducing the characteristics of the redox flow battery cell, it is preferable not to use a support.

[0281] <Diaphragm electrode assembly> The diaphragm electrode assembly in this embodiment has a structure in which a diaphragm is joined to at least one of a first electrode and a second electrode. This joining means that the diaphragm is connected to at least one of the first electrode and the second electrode, and by joining, the diaphragm can be integrated with at least one of the first electrode and the second electrode. For example, in a diaphragm electrode assembly comprising a first electrode, a second electrode, and a diaphragm, when assembling a redox flow battery cell, the process of assembling the first electrode, the diaphragm, and the second electrode in order becomes unnecessary, and it can be reduced to a single process, which tends to reduce manufacturing costs, and is therefore sometimes preferred.

[0282] The method for joining the first electrode, at least one of the second electrodes, and the diaphragm is not particularly limited, but examples include using a hot press and / or a hot roll press.

[0283] The temperature at which bonding occurs is not particularly limited, but it is preferable to set it above room temperature, as insufficient bonding between the diaphragm and the electrode tends to reduce the elastic modulus of the diaphragm and improve the bonding between the diaphragm and the electrode. Since deterioration of the diaphragm tends to be suppressed, the bonding temperature is preferably 250°C or lower, more preferably 200°C or lower, even more preferably 170°C or lower, and particularly preferably 150°C or lower.

[0284] The pressure used during joining is not particularly limited, but is greater than 0 MPa. Since joining between the diaphragm and the electrode tends to improve, it is preferably 0.01 MPa or higher, more preferably 0.05 MPa or higher, even more preferably 0.08 MPa or higher, and particularly preferably 0.1 MPa or higher. Since deterioration of the electrode tends to be suppressed, it is preferably 100 MPa or lower, more preferably 50 MPa or lower, even more preferably 20 MPa or lower, and particularly preferably 10 MPa or lower.

[0285] The bonding time is not particularly limited, but is greater than 0 seconds. Since bonding between the diaphragm and the electrode tends to improve, it is preferably 0.01 seconds or more, more preferably 0.1 seconds or more, even more preferably 0.5 seconds or more, and particularly preferably 1 second or more. Since the cost of manufacturing the diaphragm-electrode assembly tends to be reduced, it is preferably 10 hours or less, more preferably 5 hours or less, even more preferably 2 hours or less, and particularly preferably 1 hour or less.

[0286] The atmosphere used during bonding is not particularly limited, but examples include air, nitrogen, and argon. Air and nitrogen are preferred, and air is more preferred, as they tend to reduce the cost of manufacturing the diaphragm electrode assembly.

[0287] <Redox flow battery> A redox flow battery can be formed by stacking the redox flow battery cells of this embodiment. When stacking, electrical current can be supplied between each redox flow battery cell via a bipolar plate.

[0288] The material of the bipolar plate is not particularly limited, and examples include carbon, graphite, and metal. Furthermore, the material may contain dispersed carbon particles, carbon fibers, metal particles, metal fibers, graphene, and carbon nanotubes. It can be used individually or in combination with other types.

[0289] Bipolar plates may have various flow paths to improve contact between the electrodes and the electrolyte. The flow paths are not particularly limited, and examples include serpentine, interdigitated, parallel, multi-parallel, discontinuous, and combinations thereof.

[0290] By using the redox flow battery cell and redox flow battery of this embodiment, it is possible to provide a mechanism that smooths the supply and demand of power and stabilizes fluctuating power obtained from renewable energy sources such as solar and wind energy. More specifically, it is possible to provide integration of power obtained from renewable energy sources, power peak load shifting, stabilization of transmission and distribution networks, base load power, energy arbitrage, support for weak transmission and distribution networks, frequency regulation, and any combination of the above. It can also be used as a power source for remote camps, forward operating bases, power transmission and distribution telecommunications, remote sensors, etc., that do not utilize transmission and distribution networks.

[0291] The redox flow battery cell and the redox flow battery of this embodiment may be equipped with a control system and a power adjustment unit.

[0292] The control system allows for the control of various valves, pumps, circulation circuits, sensors, mitigation devices, other electronic / hardware control devices, and safety protection devices.

[0293] By using a power adjustment unit, the voltage and current of the input power can be converted to a format optimized for redox flow battery cells and / or redox flow batteries, and the voltage and current of the output power can be converted to a format optimized for any application. For example, when redox flow battery cells and / or redox flow batteries are connected to a power grid, in the charging cycle, the power adjustment unit can convert the input AC power to DC power of a suitable voltage and current. In the discharge cycle, the redox flow battery cells and / or redox flow batteries generate DC power, and the power adjustment unit can convert this DC power to AC power of a voltage and frequency suitable for transmission to the power grid.

[0294] [Fourth Embodiment] Next, a fourth embodiment will be described.

[0295] Patent Document 5 uses a solvent containing a large amount of ethanol, which is a protic solvent (in the example of Patent Document 1, the ethanol content is 50% by mass). When the fluororesin content in the solution is increased, the viscosity of the solution tends to increase, making it difficult to store the solution within the optimal viscosity range for the film formation process by coating and drying. In addition, the rate of change in the viscosity of the solution over time tends to increase, making it difficult to store the solution within the optimal viscosity range for the film formation process by coating and drying.

[0296] Patent Document 6 uses N,N-dimethylformamide as a hydrophilic and high-boiling point solvent. When an ion exchange membrane is manufactured by coating and drying a polymer electrolyte solution and then heat-treating it, the N,N-dimethylformamide remaining in the ion exchange membrane decomposes, generating dimethylamine as an impurity. This poses a problem in that, depending on the application, the properties may deteriorate due to this impurity.

[0297] Patent Document 7 and Non-Patent Document 1 state that it is difficult to sufficiently increase the molecular weight of perfluorosulfonic acid polymers with a large proportion of sulfonic acid groups, and that when attempting to obtain an ion exchange film by coating and drying using a solution of a perfluorosulfonic acid polymer with a large proportion of sulfonic acid groups that does not have a sufficiently large molecular weight, a film with sufficient mechanical strength cannot be obtained with conventionally known solvent compositions. Therefore, there is a need for a perfluorosulfonic acid polymer film with a large proportion of sulfonic acid groups that has sufficient mechanical strength.

[0298] Patent Document 8 describes how to obtain an ion exchange membrane with a thickness of 25 μm or less, which is difficult to manufacture by conventional extrusion molding techniques, by co-extruding a perfluorosulfonic acid polymer precursor with an incompatible polymer. However, although the anisotropy of the ion exchange membrane produced by this invention is reduced compared to conventionally known extruded perfluorosulfonic acid polymer ion exchange membranes, in applications where the ion exchange membrane is used immersed in an electrolyte or solvent, such as redox flow batteries or water electrolysis, the in-plane anisotropy originating from the molding method causes the polymer electrolytic membrane to swell due to the electrolyte, potentially leading to an anisotropic dimensional change of the ion exchange membrane relative to the membrane surface and adversely affecting its properties. In other words, there is a need for an ion exchange membrane containing a perfluorosulfonic acid polymer with further reduced anisotropy.

[0299] As described above, a polymer electrolyte solution containing a fluororesin with a high proportion of sulfonic acid exhibits little change in solution viscosity over time, and the viscosity of the solution can be set to an optimal viscosity range for the film formation process by coating and drying. An ion exchange membrane obtained by coating and drying the solution has sufficient mechanical strength, yet has few crack defects per unit area, and can have an appropriate film thickness that results in low electrical resistance, while minimizing the in-plane anisotropy of the electrolyte membrane. This has been difficult to achieve with conventional known techniques.

[0300] The objective of this embodiment is to provide a novel polymer electrolyte solution for forming a polymer film.

[0301] The polymer electrolyte solution according to this embodiment comprises a fluororesin having a structural unit represented by the following general formula G1, with an equivalent weight of 500 g / eq or more and less than 1,000 g / eq, A solvent containing water, an aliphatic alcohol, and an aliphatic carboxylic acid, A polymer electrolyte solution containing, The mass ratio of the total aliphatic carboxylic acid and its reactants to the total mass of the solvent is 100:1 to 100:50. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.)

[0302] According to this embodiment, it is possible to provide a novel polymer electrolyte solution that forms a polymer film.

[0303] Furthermore, according to the above embodiments, the viscosity of the solution changes little over time, the viscosity of the solution can be set to an optimal viscosity range for the film formation process by coating and drying, and a polymer electrolyte solution containing a fluororesin with a high sulfonic acid ratio can be provided. In addition, an ion exchange membrane containing a fluororesin with a high sulfonic acid ratio can be provided that has sufficient mechanical strength, few crack defects per unit area, an appropriate film thickness that can result in low electrical resistance, low in-plane anisotropy of the electrolyte membrane, excellent film thickness uniformity, and a sufficiently large surface area. Furthermore, a cell for a redox flow battery and a redox flow battery can be provided using the ion exchange membrane.

[0304] (Fluororesin G1) The fluororesin in this embodiment (hereinafter also referred to as "fluororesin G1") has structural units represented by the following general formula G1, with an equivalent weight of 500 g / eq or more and less than 1,000 g / eq. [ka] (In the formula, the definition of each substituent is the same as that of the general formula G1 described above.)

[0305] In the fourth embodiment, the fluororesin G1 preferably has a structural unit represented by the following general formula C3. -[CF2CX 1 X 2 ] a -[CF2-CF((-O-CF2-CF(CF2X 3 )) b -O c -(CFR 1 ) d -(CFR 2 ) e -(CF2) f -X 4 )] g - [C3] (In the formula, X 1 , X 2 , and X 3 Each of these is independently a halogen atom or a perfluoroalkyl group having 1 to 3 carbon atoms, and the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 1 , R 2 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a fluorochloroalkyl group, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 4 This is a monovalent group represented by the formula -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, or a divalent group represented by the formula -COOMOOC-, -SO3MO3S-, -PO3M2O3P-, or -PO3HMHO3P-. 4 If is a divalent group, X 4 The fluororesins G1 may be crosslinked via a mediated linkage. Z is a hydrogen atom, an alkali metal atom, or an amine. M is an alkaline earth metal atom. X 4 If the equation is -PO3Z2, the two Zs may be the same or different.

[0306] X 1 , X 2 , and X 3Each of these is independently a halogen atom or a perfluoroalkyl group having 1 to 3 carbon atoms, and the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 1 , X 2 , and X 3 As such, because raw materials are readily available and the manufacturing cost of fluororesin G1 tends to be reduced, fluorine atoms, chlorine atoms, and perfluoroalkyl groups having 1 to 3 carbon atoms are preferred, fluorine atoms, chlorine atoms, and perfluoroalkyl groups having 1 carbon atom are more preferred, fluorine atoms and chlorine atoms are even more preferred, and fluorine atoms are particularly preferred. R 1 , R 2 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a fluorochloroalkyl group, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 1 , R 2 From the viewpoint of easy availability of raw materials and the tendency to suppress the manufacturing cost of fluororesin G1, fluorine atoms and unsubstituted C1-C3 perfluoroalkyl groups are preferred. Furthermore, from the viewpoint of improving the chemical stability of fluororesin G1, such as its resistance to oxidative degradation, fluorine atoms and trifluoromethyl groups are more preferred, with fluorine atoms being particularly preferred. X 4 This is a monovalent group represented by the formula -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, or a divalent group represented by the formula -COOMOOC-, -SO3MO3S-, -PO3M2O3P-, or -PO3HMHO3P-. 4 If is a divalent group, X 4 The fluororesins G1 may be crosslinked via a mediated linkage. Z is a hydrogen atom, an alkali metal atom, or an amine. M is an alkaline earth metal atom. X 4When it is -PO3Z2, the two Zs may be the same as or different from each other. The alkali metal is not particularly limited, and a lithium atom, a sodium atom, or a potassium atom is preferable, and a sodium atom or a potassium atom is more preferable. The amines are not particularly limited, and include NH4, NH3R 10 , NH2R 10 R 11 , NHR 10 R 11 R 12 , NR 10 R 11 R 12 R 13 of the structure. R 10 , R 11 , R 12 , and R 13 may be the same as or different from each other, and are not particularly limited as long as they are generally used structures, and examples include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. The aliphatic hydrocarbon group is preferably a monovalent group represented by C n H 2n+1 (n represents an integer of 1 or more, preferably an integer of 1 to 20, and more preferably an integer of 1 to 10). The aromatic hydrocarbon group is preferably a phenyl group or a naphthyl group. M is an alkaline earth metal atom, which is not particularly limited, but a magnesium atom or a calcium atom is preferable. a and g are numbers that satisfy 0 ≦ a < 1, 0 < g ≦ 1, and a + g = 1. b is an integer from 0 to 8. c is 0 or 1. d, e, and f are each independently an integer from 0 to 6 (however, d, e, and f are not 0 at the same time).

[0307] In the fluororesin G1 having the structural unit represented by the above general formula C3, from the viewpoint of further achieving better balance between dispersibility and film strength, it is preferably represented by the following general formula C1 or the following general formula C4, and more preferably represented by the following general formula C4. -[CF2CF2] a -[CF2-CF((-O-CF2-CF(CF3)) b -O-(CF2) c -SO3X)] d- [C1] (In the formula, a and d are such that 0 ≤ a < 1, 0 ≤ d < 1, and a + d = 1. b is an integer between 1 and 8. c is an integer between 0 and 10. X is a hydrogen atom or an alkali metal atom.) -[CF2CF2] e -[CF2-CF((-O-(CF2) f -SO3X)] g - [C4] (In the formula, e and g are such that 0 ≤ e < 1, 0 ≤ g < 1, and e + g = 1. f is an integer between 0 and 10. Y is a hydrogen atom or an alkali metal atom.) Fluororesin G1 can be a prepared product made by a known method or a commercially available product.

[0308] (polymer electrolyte) The polymer electrolyte in this embodiment includes fluororesin G1, which is a type of polymer electrolyte. The ratio of fluororesin G1 to the polymer electrolyte is preferably 70% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more. When the ratio of fluororesin G1 to the polymer electrolyte is 70% by mass or more, the current efficiency of the fuel cell tends to be excellent when used in a fuel cell. The fluororesin G1 used in the polymer electrolyte may be used alone or in combination of multiple types.

[0309] The polymer electrolyte in this embodiment may contain, as a polymer electrolyte different from the fluororesin G1, acidic polymers such as perfluorocarboxylic acid polymers, partially fluorinated sulfonic acid polymers, partially fluorinated carboxylic acid polymers, etc., and basic polymers such as azole polymers (including imidazole polymers), amine polymers, etc. The acidic polymer and the basic polymer may be used individually or in combination of multiple types. When the electrolyte includes fluororesin G1 and the basic polymer as the polymer electrolyte, the resulting ion exchange membrane used in the fuel cell tends to exhibit improved chemical durability during fuel cell operation. The polymer electrolyte in this embodiment may contain polymers such as polyethylene glycol, polyphenylene ether, polyphenylene sulfide, polyetherimide, polysulfone, polyetherketone, polyetheretherketone, polyetheretherimide, polyamide, polyimide, and polyamideimide. The aforementioned polymer may be used individually or in combination of multiple types. The mass percentage of the polymer that may be contained in the polymer electrolyte is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, because this tends to impart the properties of the polymer to the ion exchange membrane while suppressing a decrease in the mechanical strength of the ion exchange membrane.

[0310] The equivalent mass (hereinafter also referred to as "EW") of the fluororesin G1 having a structural unit represented by general formula C1 is preferably 600 g / eq or more and less than 1,000 g / eq, more preferably 650 g / eq or more and 980 g / eq or less, and even more preferably 700 g / eq or more and 950 g / eq or less, from the viewpoint of reducing the electrical resistance of the diaphragm and improving the mechanical strength of the diaphragm when an ion exchange membrane containing fluororesin G1 is used as a diaphragm for a redox flow battery. Note that "equivalent mass (EW) of fluororesin G1" refers to the dry weight per equivalent of sulfonic acid groups.

[0311] The equivalent mass (EW) of the fluororesin G1 having a structural unit represented by general formula C4 is preferably 400 g / eq or more and less than 1,000 g / eq, more preferably 450 g / eq or more and 980 g / eq or less, even more preferably 500 g / eq or more and 950 g / eq or less, even more preferably 600 g / eq or more and 950 g / eq or less, and even more preferably 700 g / eq or more and 950 g / eq or less, from the viewpoint of reducing the electrical resistance of the diaphragm and improving the mechanical strength of the diaphragm when an ion exchange membrane containing fluororesin G1 is used as a diaphragm for a redox flow battery.

[0312] The degree of polymerization of the fluororesin G1 precursor can be indicated by the melt flow rate (hereinafter also referred to as "MFR"). The MFR of the fluororesin G1 precursor is not particularly limited, but is preferably 100 g / 10 min or less, more preferably 50 g / 10 min or less, and even more preferably 30 g / 10 min or less. An MFR of 100 g / 10 min or less tends to yield an ion exchange membrane with excellent mechanical strength. Furthermore, an MFR of 0.01 g / 10 min or more is preferable, more preferably 0.1 g / 10 min or more, and even more preferably 0.3 g / 10 min or more. An MFR of 0.01 g / 10 min or more tends to allow for more efficient and finer dispersion and dissolution of the fluororesin G1 when it is prepared in solution. The MFR can be measured by the method described in the examples.

[0313] (Polymer electrolyte solution) The polymer electrolyte solution in this embodiment comprises a fluororesin G1 having an equivalent weight of 500 g / eq or more and less than 1,000 g / eq, and a solvent containing water, an aliphatic alcohol, an aliphatic carboxylic acid, and an aliphatic ester. The dissolution equipment for obtaining a uniform, colorless, and transparent polymer electrolyte solution from an emulsion containing fluororesin G1 and a solvent is not particularly limited, but it is preferable to use equipment that continuously dissolves the fluororesin G1 and the solvent. The equipment that continuously dissolves the materials is heated by a heating means described later, and the perfluorosulfonic acid polymer in the emulsion passing through the dissolution equipment dissolves in the solvent under the conditions inside the dissolution equipment, allowing a uniform polymer electrolyte solution to be discharged from the dissolution equipment.

[0314] The equipment for continuous dissolution preferably includes a pump for continuously supplying an emulsion containing fluororesin G1 and a solvent into the dissolution equipment, dissolution equipment for continuously dissolving fluororesin G1 in the solvent, a heating means for heating the dissolution equipment, and a cooling means.

[0315] The pump is used to continuously supply an emulsion containing fluororesin G1 and a solvent into the dissolution equipment. The type of pump is not particularly limited, but examples include turbo pumps, piston pumps, plunger pumps, diaphragm pumps, gear pumps, vane pumps, and screw pumps. Among these, plunger pumps, diaphragm pumps, multi-cylinder pumps, and accumulators are preferred from the standpoint of safety, high pressure resistance, high quantitative accuracy from the standpoint of productivity, and high discharge pressure. Furthermore, from the standpoint of suppressing pulsation, multi-cylinder pumps and accumulators are even more preferred. Pumps may be used individually or in combination of multiple types.

[0316] While there are no particular limitations on the dissolution equipment, examples include devices in which the fluid flow within the dissolution equipment is of the plug flow type.

[0317] The shape of the dissolution equipment is not particularly limited, but a tube is preferred, for example. A tube shape tends to improve productivity and dissolution efficiency. The tube shape is not particularly limited and can be straight, coiled, or angular. Among these, a coiled shape is preferred from the viewpoint of installation area and stable operation. The outer diameter of the tube is preferably 1 / 16 to 2 inches, and more preferably 1 / 4 to 1 / 2 inches, from the viewpoint of productivity and dissolution efficiency. In addition, commercially available pipes of 6A to 500A may be used. Furthermore, from the viewpoint of productivity and dissolution efficiency, an inline mixer, wire mesh, metal packing, etc. may be installed inside the tube.

[0318] The melting equipment is not particularly limited, but a tubular metal type is preferred. The material of the melting equipment is not particularly limited, but the optimal material should be selected from the viewpoint of corrosion resistance, and examples include SUS-based materials, Hastelloy-based materials, titanium-based materials, zirconia-based materials, and tantalum-based materials. Among these, SUS-based materials and materials with the same composition as Hastelloy (a registered trademark of Haynes Corporation, USA) are preferred because they offer an excellent balance between corrosion resistance and cost, materials with the same composition as SUS316 and Hastelloy C are more preferred, and materials with the same composition as Hastelloy C276 are particularly preferred. The same composition as Hastelloy, Hastelloy C, and Hastelloy C276 refers to a material with a composition containing 56-60% by mass of Ni, 16-22% by mass of Cr, 13-16% by mass of Mo, 2-6% by mass of W, 3-8% by mass of Fe, and 2.5% by mass or less of Co. By using such metal dissolution equipment, the dissolution process can be carried out at high temperature and high pressure, and the perfluorosulfonic acid polymer contained in the resulting polymer electrolyte solution tends to have improved stability at the main chain ends of the perfluorosulfonic acid polymer. The inner wall of the tube may be lined. The lining is not particularly limited, but examples include fluorine lining and glass lining. By using dissolution equipment with such lining, the dissolution process can be carried out at relatively low temperature and low pressure, and the concentration of F ions and Fe ions in the resulting polymer electrolyte solution tends to be kept low.

[0319] The tube wall thickness is not particularly limited, but the optimal wall thickness should be selected from the viewpoint of pressure resistance. The inner diameter of the tube is not particularly limited, but from the viewpoint of productivity and dissolution efficiency, it is preferably 1 to 50 mm, and more preferably 4 to 50 mm.

[0320] The surface roughness of the inner wall of the tube is not particularly limited and may be uneven or mirror-like. From the viewpoint of dissolution efficiency, the maximum height of the surface roughness of the inner wall of the tube is preferably 50 μm or less, more preferably 25 μm or less, and even more preferably 10 μm or less. The maximum height of the surface roughness of the inner wall of the tube is a value obtained by, for example, using a laser microscope, taking a reference length from the roughness curve in the direction of its average line, and measuring the distance between the peak line and the trough line of this taken portion in the direction of the vertical magnification of the roughness curve.

[0321] The tube length depends on the required dissolution time (residence time). Specifically, the tube length can be calculated from the relationship between the tube's inner diameter and the product of the dissolution time (min) and the supply rate (L / min), such that the product is equal to or less than the internal volume of the heated tube. Dissolution time (min) × supply rate (L / min) ≤ internal volume of the tube Internal volume of tube = (Inner diameter of tube / 2)² × π × Length of tube

[0322] When using multiple dissolving equipment units in series, which are tubular in shape, the units may be connected by identical or different shaped unions, T-type unions, check valves, safety valves, back pressure valves, pressure gauges, thermometers, etc. Furthermore, productivity can be increased by using multiple dissolving equipment units in parallel to increase the internal volume.

[0323] Heating means for melting equipment are used to heat the melting equipment. While not particularly limited, heating methods include using a heat transfer medium such as hot air, hot water, steam, or silicone oil to heat the melting equipment. The heat transfer fluid may be used alone or in combination of multiple types. Among heat transfer fluids, hot air is preferred because it can be used easily, and the melting equipment can be placed in a constant temperature bath set to a specific temperature using hot air.

[0324] The pressure within the dissolution equipment in a continuous dissolution system is not particularly limited, but it is preferable to have a pressure adjustment means that adjusts the pressure to exceed the vapor pressure of the solvent at the heating temperature of the dissolution equipment. The pressure adjustment means may be installed on the downstream side in the supply direction of the dissolution equipment, on the upstream side in the supply direction, both upstream and downstream, or within the dissolution equipment itself. The means of regulating pressure are not particularly limited, but examples include back pressure valves, automatic pressure regulating valves (PICs), and the pumps mentioned above. By using a back pressure valve or an automatic pressure regulating valve (PIC), the pressure inside the dissolution equipment can be kept constant, that is, pressure fluctuations can be minimized, thereby improving the dispersibility of the polymer electrolyte solution and preventing clogging inside the dissolution equipment. In addition, the inside of the dissolution equipment can be pressurized by using a pump. Furthermore, the system from the pump to the pressure regulating means (back pressure valve) can be considered as a sealed container with constant pressure. In the aforementioned continuous dissolution equipment, the dispersibility of the polymer electrolyte in the polymer electrolyte solution is further improved, and such an electrolyte solution with improved dispersibility tends to be obtained at a higher concentration and in a shorter time.

[0325] Equipment for continuous dissolution preferably includes a cooling means downstream of the dissolution equipment that cools the polymer electrolyte solution while maintaining a pressure exceeding the vapor pressure of the solvent at the heating temperature inside the dissolution equipment. Having such a cooling means tends to further suppress clogging inside the dissolution equipment when discharging the polymer electrolyte solution. The cooling method is not particularly limited, but examples include a method in which the polymer electrolyte solution is cooled by passing it through a cooling tube, or a method in which the polymer electrolyte solution is air-cooled by passing it through a tube at room temperature without passing it through a cooling tube.

[0326] <Solvent> The polymer electrolyte solution according to this embodiment comprises water, an aliphatic alcohol, and an aliphatic carboxylic acid. The polymer electrolyte solution according to this embodiment may also contain a reaction product of the aliphatic carboxylic acid. Examples of reaction products of the aliphatic carboxylic acid include aliphatic carboxylic acid esters obtained by the condensation of an aliphatic carboxylic acid and an aliphatic alcohol.

[0327] The mass ratio of the total aliphatic carboxylic acid and its reactants to the total mass of the solvent is 100:1 to 100:50. By keeping the ratio within this range, the occurrence of crack defects in the resulting ion exchange membrane can be suppressed. The mass ratio is preferably 100:3 to 100:40, more preferably 100:4 to 100:35, and even more preferably 100:5 to 100:30.

[0328] (Aliphatic carboxylic acid) In this embodiment, the aliphatic carboxylic acid is a compound having a carboxyl group (-COOH group), and the number of carbon atoms in the aliphatic carboxylic acid is preferably 1 to 5, with examples including formic acid, acetic acid, propionic acid, butyric acid, and isobutyric acid. When forming a film using a polymer electrolyte solution, if water is present, the aliphatic carboxylic acid tends to have an excellent balance of miscibility with water and solvation of the hydrophobic parts of the polymer electrolyte. Therefore, the number of carbon atoms in the aliphatic carboxylic acid is more preferably 1 to 4, even more preferably 1 to 3, and particularly preferably acetic acid. The boiling point of the carboxylic acid is preferably 165°C or lower, and more preferably 150°C or lower, as this tends to improve drying properties during film formation. The ratio of aliphatic carboxylic acid to solvent in a polymer electrolyte solution is preferably 1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 40% by mass or less, and even more preferably 3% by mass or more and 30% by mass or less, because when water is present during film formation using the polymer electrolyte solution, it tends to have an excellent balance between miscibility with water and solvation of the hydrophobic parts of the polymer electrolyte. When the ratio of aliphatic carboxylic acid is 1% by mass or more, the rate of change in the solution viscosity of the polymer electrolyte solution over time tends to be small. When the ratio of aliphatic carboxylic acid is 30% by mass or less, the drying properties of the polymer electrolyte solution during film formation tend to be improved.

[0329] (Aliphatic alcohols) In this embodiment, an aliphatic alcohol is a compound having a hydroxyl group (-OH group), and the number of carbon atoms is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 4, from the viewpoint of having an excellent balance between miscibility with water and solvation of the hydrophobic sites of the polymer electrolyte when water is present during film formation using a polymer electrolyte solution. Specific examples of aliphatic alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, etc., among which methanol, ethanol, 1-propanol, and 1-butanol are preferred. The boiling point of the alcohol is preferably 165°C or lower, and more preferably 150°C or lower, as this improves drying properties during film formation. The ratio of aliphatic alcohol to solvent in the polymer electrolyte solution is preferably 5% by mass or more and 70% by mass or less, more preferably 5% by mass or more and 60% by mass or less, and even more preferably 5% by mass or more and 50% by mass or less. When the alcohol ratio is 5% by mass or more, the puncture strength of the ion exchange membrane tends to improve. When the alcohol ratio is 50% by mass or less, the rate of change in the viscosity of the polymer electrolyte solution over time tends to be small.

[0330] (Aliphatic ester) In this embodiment, an aliphatic ester is a compound having an ester group (-COOR group: R is a hydrocarbon group), and the number of carbon atoms is preferably 2 to 10, more preferably 2 to 8, and even more preferably 2 to 6, because when forming a film using a polymer electrolyte solution and water is present, a good balance of miscibility with water and solvation of the hydrophobic sites of the polymer electrolyte is favored. Specific examples of aliphatic esters include methyl formate, ethyl formate, n-propyl formate, isopropyl formate, n-butyl formate, sec-butyl formate, isobutyl formate, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, sec-butyl acetate, isobutyl acetate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, sec-butyl butyrate, and isobutyl butyrate. Among these, methyl acetate, ethyl acetate, n-propyl acetate, and n-butyl acetate are preferred. Since the drying properties during film formation are improved, the boiling point of the ester is preferably 160°C or lower, and more preferably 150°C or lower. The ratio of aliphatic ester to solvent in the polymer electrolyte solution is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 35% by mass or less, and even more preferably 1% by mass or more and 30% by mass or less. When the ester ratio is 1% by mass or more, the puncture strength of the ion exchange membrane tends to improve. When the ester ratio is 30% by mass or less, the rate of change in the viscosity of the polymer electrolyte solution over time tends to be small.

[0331] The viscosity of the polymer electrolyte solution (at 25°C) is preferably between 10 mPa·s and 2,000 mPa·s, more preferably between 50 mPa·s and 1,000 Pa·s, and more preferably between 100 mPa·s and 1,000 mPa·s. An initial viscosity of 10 mPa·s or higher for the polymer electrolyte solution (at 25°C) tends to result in a uniform thickness of the polymer electrolyte solution during coating. A viscosity of 2,000 mPa·s or lower tends to result in fewer bubbles and / or a uniform thickness of the ion exchange film after coating. The pot life of a polymer electrolyte solution's viscosity is defined as the number of days required for the viscosity (at 25°C) to more than double when measured within 24 hours of preparation, or the number of days required for the viscosity to exceed 2,000 mPa·s, for a polymer electrolyte solution adjusted within a viscosity range of 10 mPa·s or more and 2,000 mPa·s or less. This is the lesser of the two. In particular, for perfluorocarbon sulfonic acid, which has the general formula C4, conventional known techniques have the problem of a short pot life within the above appropriate viscosity range. By using the solvent composition of the present invention, the pot life can be improved.

[0332] The solid content in the polymer electrolyte solution is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less. When the solid content in the polymer electrolyte solution is 10% by mass or more, the drying time required during coating tends to be shortened. When the solid content in the polymer electrolyte solution is 35% by mass or less, the viscosity of the polymer electrolyte solution tends to be lower, and the rate of increase in the solution viscosity over time also tends to be lower.

[0333] (Ion exchange membrane) The ion exchange membrane in this embodiment can be obtained, for example, by applying the polymer electrolyte solution of this embodiment to a known substrate (coating step), drying it (drying step), cooling it as necessary (cooling step), and then heat-treating it (heat treatment step). Coating and drying refers to a series of steps including at least a coating step and a drying step.

[0334] The coating method in the coating process is not particularly limited, and known coating methods can be used. For example, coating can be applied to the support using various blade coaters, roll coaters, air knife coaters, bar coaters, and other devices. The drying temperature in the drying process is not particularly limited, but may be, for example, around room temperature to 200°C. Since the thermal decomposition of the perflucarbon osulfonic acid polymer tends to be suppressed, it is preferable that the drying temperature be 150°C or lower when the drying time is long. Furthermore, in high-speed coating with a short drying time, an ion exchange film can be obtained even with a short drying time by setting the drying temperature to 200°C or lower. The drying time in the drying process is not particularly limited and may range from, for example, 10 seconds to 120 minutes. The drying process may be carried out by gradually changing the drying temperature. The drying method is not particularly limited and may include, for example, hot air drying or electromagnetic wave drying, and may be combined with two or more other drying methods. The cooling temperature in the cooling process may be, for example, around room temperature, and the cooling time may be, for example, around 30 to 90 minutes. If a heat treatment process is performed after the drying process, the heat treatment temperature may be, for example, around 100 to 200°C, and the heat treatment time may be around 5 to 15 minutes.

[0335] In dynamic light scattering particle size measurement, the scattering intensity ratio (A / B) of the polymer electrolyte solution is not particularly limited, but is approximately 1.0 × 10⁻⁶. -2 The above is preferably 1.0 × 10 or less. The scattering intensity ratio (A / B) is 1.0 × 10 -2 More preferably, the above is 1.0 × 10 or less, and 1.0 × 10 -1 More preferably, the value is 5.0 or less, and 5.0 × 10 -1It is particularly preferable that the ratio is 2.0 or less. The scattering intensity ratio (A / B) in dynamic light scattering particle size measurement is used to determine the dispersibility of polymers in a polymer electrolyte solution. In other words, it can serve as a measure of solubility. The scattering intensity ratio (A / B) can be measured by the method described in the examples below. A scattering intensity (1 / nm) ratio (A / B) of 1.0 × 10⁻¹⁰ or less tends to improve the dispersibility of the polymer electrolyte in the solvent. In other words, as the scattering intensity (B) increases relative to the scattering intensity (A), the dispersibility of the polymer electrolyte in the solvent tends to improve. A scattering intensity ratio (A / B) of 1.0 × 10⁻¹⁰ -2 As a result of the above, the decomposition and breakdown of polymer electrolytes into smaller molecules tends to be suppressed. The scattering intensity ratio (A / B) can be made larger by shortening the residence time or lowering the dissolution temperature, and smaller by lengthening the residence time or raising the dissolution temperature, thereby achieving the desired scattering intensity ratio (A / B). As a criterion for determining the solubility of a polymer electrolyte in a solvent, in addition to the scattering intensity ratio (A / B) in the dynamic light scattering particle size measurement described above, the transmittance at a wavelength of 800 nm in UV measurement of a polymer electrolyte solution with a solid weight of 20% by mass can also be used. The transmittance of the polymer electrolyte solution is not particularly limited, but it is preferably 90%T or higher, more preferably 95%T or higher, and even more preferably 98%T or higher. A transmittance of 90%T or higher in the polymer electrolyte solution tends to improve the dispersibility of the polymer electrolyte in the solvent. The UV measurement can be performed by the method described in the examples below.

[0336] The concentration of fluoride ions in the polymer electrolyte is not particularly limited, but it is preferably between 0.1 ppm (ppm stands for parts per million) and 500 ppm relative to the solid content weight of the fluororesin G1. By setting the fluoride ion concentration to 500 ppm or less, the heat-resistant water solubility of the ion exchange membrane and the chemical durability of the fuel cell when the ion exchange membrane is used as an electrode catalyst layer for a fuel cell tend to improve. The Fe concentration in the ion exchange membrane is not particularly limited, but is preferably 0.010 ppm or more and 10 ppm or less, more preferably 0.050 ppm or more and 5 ppm or less, and even more preferably 0.10 ppm or more and 1 ppm or less, relative to the solid content weight of the fluororesin G1. When the Fe concentration is 10 ppm or less, when the ion exchange membrane is used in a fuel cell, the concentration of Fe that induces radical generation during fuel cell operation is reduced, the degradation of the ion exchange membrane is suppressed, and the chemical durability of the fuel cell tends to improve. When the Fe concentration is 0.010 ppm or more, the polymer electrolyte solution and the ion exchange membrane can be manufactured without going through a process to remove Fe, and productivity tends to improve.

[0337] The structure of the polymer chain ends of the fluororesin G1 contained in the ion exchange membrane is not particularly limited, but examples include -CF2H groups, -CF3 groups, -COOH groups, and -COONa groups. Among these, the -CF2H group is preferred. The amount of -CF2H groups relative to the total number of polymer chain ends of fluororesin G1 is preferably 40% or more, more preferably 50% or more, and even more preferably 90% or more. When the amount of -CF2H groups relative to the total number of polymer chain ends of fluororesin G1 is 40% or more, Fenton resistance is improved compared to ion exchange membranes whose ends are -COOH groups or -COONa groups, and when the ion exchange membrane is used in a fuel cell, the chemical durability of the fuel cell tends to improve. In addition, compared to ion exchange membranes whose ends are -CF3 groups, productivity tends to improve because there is no need to go through post-load manufacturing processes such as fluorination steps.

[0338] The converted puncture strength of the ion exchange membrane (the value obtained by converting the puncture strength in a wet state to a value per 25 μm) is preferably 30 gf / 25 μm or higher, more preferably 40 gf / 25 μm or higher, and even more preferably 50 gf / 25 μm or higher. A converted puncture strength of 30 gf / 25 μm or higher tends to provide the mechanical strength necessary for manufacturing thin ion exchange membranes. In this embodiment, there is no particular upper limit set for the converted puncture strength, but from the viewpoint of ensuring an appropriate moisture content, it is preferable to set it to 100 gf / 25 μm or lower.

[0339] (Revolving body) In this embodiment, the winding body refers to a strip-shaped film wound around a cylindrical core. The material of the core is not particularly limited, but examples include resin and metal. Examples of resins include polyethylene, polypropylene, polystyrene, ABS resin, epoxy resin, polyester, polyvinyl chloride, polyvinylidene chloride, polyimide, polyamide, and polyamideimide.

[0340] (Width and length of the ion exchange membrane wound onto the coil) When a continuously fabricated ion exchange membrane is wound into a winding, the width of the ion exchange membrane is preferably 100 mm or more and 1,000 mm or less, more preferably 150 mm or more and 800 mm or less, and even more preferably 200 mm or more and 600 mm or less. A width of 100 mm or more allows for a larger cell area in fuel cells and redox flow batteries, resulting in higher output. A width of 600 mm or less tends to reduce variations in the film thickness of the ion exchange membrane. The length of the ion exchange membrane is preferably 0.1 m or more and 1,000 m or less, more preferably 0.5 m or more and 700 m or...

Claims

1. A layer (L1) containing a heteroaromatic structure-containing fluororesin having a structural unit represented by the following general formula A1, its saponide, or its salt, 【Chemistry 1】 (In the formula, X 1 , X 2 , X 3 , and X 4 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 1 and X 2 , or X 1 and X 3 These may be bonded to each other to form a ring structure. R 1 and R 2 may be the same or different and each is a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, and the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, R 3 This is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 4 NR 3 It is a linking group to Hc, and is a substituted or unsubstituted divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. X 10 is, -CO 2 -, -SO 2 It is a divalent group represented by the formula -, Hc is a heteroaromatic group having 4 to 30 carbon atoms, containing at least one substituted or unsubstituted nitrogen atom, and comprising a 5-membered ring and / or 6-membered ring structure, wherein the 5-membered ring and / or 6-membered ring structure is an imidazole structure, benzimidazole structure, imidazopyridine structure, pyridine structure, oxazole structure, thiazole structure, pyridazine structure, pyrimidine structure, cinnoline structure, quinazoline structure, phthalazine structure, quinoxaline structure, pteridine structure, purine structure, 2,2'-bipyridyl structure, 2,3'-bipyridyl structure, 2,4'-bipyridyl structure, 1,7-phenanthroline structure, 1,10-phenanthroline structure, or 2,2':6',2''-terpyridine structure. a and g represent the molar ratios of all constituent units contained in the resin, and are numbers that satisfy 0 ≤ a < 1, 0 < g ≤ 1, and a + g = 1. b is an integer between 0 and 8. c is either 0 or 1, d, e, and f may be the same or different, and are integers between 0 and 6. However, d, e, and f are not all zero at the same time. A layer (M1) containing a fluororesin (G1) having a structural unit represented by the following general formula G1, An ion exchange membrane having [a certain characteristic]. 【Chemistry 2】 (In the formula, X5, X6, X7, and X8 may be the same or different, and are a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X5 and X6, or X5 and X7, may be bonded to each other to form a cyclic structure, and R5 and R6 may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. X9 is a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, where Z is at least one selected from the group consisting of hydrogen atoms, alkali metal atoms, alkaline earth metal atoms, and amines, and the fluororesins may be crosslinked by ionic crosslinking via X9. h and p represent the molar ratios of all constituent units contained in the resin, and are numbers that satisfy 0 ≤ h < 1, 0 < p ≤ 1, and h + p = 1. i is an integer from 0 to 8. j is 0 or 1, k, l, and m may be the same or different, and are integers from 0 to 6. However, if k, l, and m are all 0, then X9 is CF(CF2X10)2, and X10 is a base represented by -COOZ, -SO3Z, -PO3Z2, or -PO3Hz, where Z is as described above.

2. The aforementioned layer (L1), The aforementioned layer (M1), The ion exchange membrane according to claim 1, having three or more alternating layers.

3. The ion exchange membrane according to claim 1, wherein the thickness of the layer (L1) is 3 μm or less.

4. The ion exchange membrane according to claim 1, wherein the thickness of the ion exchange membrane is 200 μm or less.

5. A layer (L3) containing a side-chain nitrogen atom-containing fluororesin having a structural unit represented by the following general formula A3, its saponide, or its salt, 【Transformation 3】 (In the formula, X 20 , X 21 , X 22 , and X 23 Each of these may be the same or different, and is a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X 20 and X 21 , or X 20 and X 22 It may also form a ring structure. R 20 , and R 21 These may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. R 22 , and R 24 This is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms. R 26 , and R 27 R is a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, 26 , and R 27 This is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, with at least one being substituted or unsubstituted. R 23 , and R 25 These may be the same or different, and are substituted or unsubstituted divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms, or substituted or unsubstituted divalent aromatic hydrocarbon groups having 6 to 10 carbon atoms, and if h is 2 or more, the R is repeated. 23 These may be the same or different. X 24 is, -CO 2 -, or -SO 2 It is a divalent group represented by -, a and g represent the molar ratios of all constituent units contained in the resin, and are numbers that satisfy 0 ≤ a < 1, 0 < g ≤ 1, and a + g = 1. b is an integer between 0 and 8. c is either 0 or 1, d, e, f, and h may be the same or different, and are integers between 0 and 6. However, d, e, and f are not all zero at the same time. A layer (M3) containing a fluororesin (G1) having a structural unit represented by the following general formula G1, 【Chemistry 4】 (In the formula, X5, X6, X7, and X8 may be the same or different, and are a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic perfluoroalkyl group having 5 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X5 and X6, or X5 and X7, may be bonded to each other to form a cyclic structure, and R5 and R6 may be the same or different, and are a hydrogen atom, a halogen atom, a substituted or unsubstituted perfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted fluorochloroalkyl group having 1 to 10 carbon atoms, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. X9 is a group represented by -COOZ, -SO3Z, -PO3Z2, or -PO3HZ, where Z is at least one selected from the group consisting of hydrogen atoms, alkali metal atoms, alkaline earth metal atoms, and amines, and the fluororesins may be crosslinked by ionic crosslinking via X9. h and p represent the molar ratios of all constituent units contained in the resin, and are numbers that satisfy 0 ≤ h < 1, 0 < p ≤ 1, and h + p = 1. i is an integer from 0 to 8. j is 0 or 1, k, l, and m may be the same or different, and are integers from 0 to 6. However, if k, l, and m are all 0, then X9 is CF(CF2X10)2, and X10 is a base represented by -COOZ, -SO3Z, -PO3Z2, or -PO3Hz, where Z is as described above. Includes, The thickness of the aforementioned layer (L3) is 3 μm or less. For redox flow batteries, Ion exchange membrane.

6. The aforementioned layer (L3), The aforementioned layer (M3), The ion exchange membrane according to claim 5, having three or more alternating layers.

7. The ion exchange membrane according to claim 5, wherein h in the general formula A3 is an integer of 1 or more.

8. The ion exchange membrane according to claim 5, wherein the thickness of the ion exchange membrane is 200 μm or less.

9. An ion exchange membrane according to any one of claims 1 to 4, for use in a redox flow battery.

10. An ion exchange membrane according to any one of claims 1 to 8 is joined to at least one electrode. Membrane electrode assembly.

11. For redox flow batteries, The membrane electrode assembly according to claim 10.

12. A first electrolyte containing a first redox active material, A second electrolyte containing a second redox active material, The first electrode in contact with the first electrolyte, The second electrode in contact with the second electrolyte, A diaphragm is placed between the first electrolyte and the second electrolyte, Includes, The diaphragm is an ion exchange membrane according to any one of claims 1 to 8. Cell for redox flow batteries.

13. A membrane electrode assembly in which a diaphragm and at least one electrode are joined together. A cell for a redox flow battery according to claim 12.

14. At least one of the first electrode and the second electrode is a carbon electrode. A cell for a redox flow battery according to claim 12.

15. At least one of the first redox active material and the second redox active material is selected from the group consisting of metallic redox active materials, nonmetallic redox active materials, and organic redox active materials. A cell for a redox flow battery according to claim 12.

16. The redox flow battery cells according to claim 12 are stacked, Redox flow battery.

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