Glassy organic framework ion conduction membrane

Abstract

Ion conducting membranes comprised of a vitreous organic framework are provided. Devices comprising the ion conducting membranes and methods of making the ion conducting membranes are also provided. Glass-like organic framework membranes may be synthesized from nitrile and / or acetyl-containing monomers using thermally controlled stepwise nitrile and / or acetyl trimerization and membrane casting techniques.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 371,152, filed on August 11, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0003] A key problem associated with electrochemical cells is the unwanted crossover of electrolytes through ion-conducting membranes that separate different phases or solutions, such as anolyte and catholyte solutions. This problem is caused by the relatively large ion-conducting channels in the polymeric ion exchange membranes of the prior art and the relatively small size difference between the redox species / products and the charge-balancing ions in the electrolyte solution. This unwanted crossover causes the electrochemical cell to have unwanted mixing of the chemical species involved in the electrochemical process and accelerated performance degradation, including rapid capacity decay and low energy efficiency of the battery. For conventional amorphous polymer membranes, this problem is exacerbated in liquid electrochemical cells because the membrane structure / pores swell in aqueous media and are even soluble in organic solvents, resulting in accelerated crossover. This is particularly troublesome for separation and extraction applications.

[0004] Additionally, electrochemical, thermal, and chemical degradation have proven to be a problem with conventional ion exchange membranes, further reducing the useful electrochemical cell life.

[0005] Although various attempts have been made to design ion conducting membranes that address the above-mentioned problems, these attempts have failed to produce membranes having low production costs, high stability under a variety of solution conditions, selective ion transport, and high ion conductivity. Summary of the invention

[0006] Ion-conducting membranes composed of glassy organic frameworks (GOFs) are provided. Also provided are devices incorporating GOF ion-conducting membranes (GOFIMs) and methods of making GOFIMs. GOFIMs that are stable against degradation in various environments, including in aqueous and / or nonaqueous solutions and / or in alkaline neutral and / or acidic solutions, can be formed.

[0007] One embodiment of an electrochemical cell comprises: (a) an anode; (b) a first electrolyte solution comprising redox-inactive ions, redox-active ions, or mixtures thereof; (c) a cathode; (d) a second electrolyte solution comprising redox-inactive ions, redox-active ions, or mixtures thereof; and (e) at least one ion-conducting membrane comprising a continuous, integral, uniform sheet of a glassy organic framework, wherein the at least one ion-conducting membrane separates (a) and (b), separates (b) and (d), or separates (c) and (d), wherein the glassy organic framework comprises a network of covalently bonded aromatic rings, wherein the aromatic rings comprise phenylene rings, 1,3,5-triazine rings, pyridine rings, pyrimidine rings, or combinations of two or more thereof.

[0008] One embodiment of a method for preparing an ion-conducting membrane comprises the steps of: (a) dissolving monomers in a trimerization catalyst to form a solution, the monomers comprising: a nitrile monomer having one or more nitrile groups; an acetyl monomer having one or more acetyl groups; a monomer having at least one nitrile group and at least one acetyl group; a nitrogen-containing aromatic heterocyclic monomer comprising functional groups on a ring nitrogen atom in addition to at least two nitrile functional groups; or a combination of two or more thereof, and optionally, a charged monofunctional dopant monomer comprising a single nitrile group or a single acetyl group, wherein the monomers react to form intermediates dissolved in the solution; (b) forming a film of the solution on a surface of a substrate; and (c) heating the film to initiate the reaction of the intermediates, thereby forming an ion-conducting membrane comprising a continuous, integral, uniform sheet of a glassy organic framework comprising a network of covalently bonded phenylene rings, 1,3,5-triazine rings, pyridine rings, pyrimidine rings, or combinations thereof.

[0009] One embodiment of a method for preparing an ion-conducting membrane comprises the following steps: (a) performing a nucleophilic aromatic substitution reaction between a halogenated aromatic monomer having at least two nitrile functional groups and a thiol compound to form a thiolated aromatic monomer having at least two nitrile functional groups; (b) dissolving the thiolated aromatic monomer in a trimerization catalyst to form a solution, wherein the thiolated aromatic monomer reacts to form an intermediate soluble in the solution; (c) forming a film of the solution on a substrate surface; and (d) heating the film to induce the reaction of the intermediate, thereby forming a membrane comprising a sheet of a glassy organic framework comprising a thiolated network of covalently bonded 1,3,5-triazine rings.

[0010] One embodiment of a method of making a charged ion conducting membrane comprises the steps of: sulfonating phenyl rings in an amorphous organic framework comprising a network of covalently bonded phenylene rings; and deprotonating the sulfonate groups.

[0011] One embodiment of a method of making a charged ion-conducting membrane comprises the steps of: chloromethylating phenyl rings in an amorphous organic framework comprising a network of covalently bonded phenylene rings; and reacting the chloromethyl groups with a tertiary amine to convert the chloromethyl groups into quaternary ammonium groups.

[0012] Other principal features and advantages of the present invention will become apparent to those skilled in the art after reviewing the following drawings, detailed description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Illustrative embodiments of the present invention will now be described with reference to the drawings, wherein like reference numerals refer to like elements.

[0014] Figure 1 Represents the glassy structure of GOF formed by bonded phenylene groups.

[0015] Figure 2 The structures of alkane dinitrile, 2,4,6-tricyano-1,3,5-triazine, 1,3,5-tricyanobenzene, succinonitrile, perfluoroterephthalonitrile, perchloroterephthalonitrile, 1,2,3-propanetricarbonitrile, 2-methylglutaronitrile, 3,3-bis(cyanomethyl)glutaronitrile, 1,4-benzodicarbonitrile, [1,1'-biphenyl]-4,4'-dicarbonitrile, 1,4-benzodiacetonitrile, 2,2'-([1,1'-biphenyl]-4,4'-diyl)diacetonitrile and 9H-carbazole-3,6-dicarbonitrile monomers are shown.

[0016] Figure 3 Shown is the structure of an aromatic nitrile monomer containing a plurality of phenylene rings, wherein at least some of the phenylene rings are linked by ether groups, wherein at least some of the phenylene rings have fluorine substituents on them.

[0017] Figure 4 The structures of aliphatic alkanediones (e.g., butanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, and 2,5-hexanedione), cycloaliphatic diketones (e.g., 1,4-cyclohexanedione and 1,3-cyclohexanedione), 1,3,5-cyclohexanetrione, 1,3-cyclopentanedione, 2,6-diacetylpyridine, 1-(1,4-phenylene)bisacetyl ketone, 4-acetoxy-4'-acetylbiphenyl, and 1,3,5-triacetylbenzene monomers are shown.

[0018] Figure 5 Shown are the structures of two mixed acetonitrile monomers, which include at least one acetyl group and at least one nitrile group.

[0019] Fig. 6A The structures of three mononitrile monomers are shown. Figure 6B The structures of the three monoacetyl monomers are shown.

[0020] Figure 7A step-by-step condensation reaction scheme for the synthesis of GOFIM is shown.

[0021] Figure 8 The macrocycles formed within the larger GOF are shown to illustrate the ability to tune the average pore size in neutral (uncharged) GOFs by choice of starting monomers.

[0022] Fig. 9 The macrocycle formed within a larger GOF is shown to illustrate the ability to tune the pore surface polarity in a neutral GOF by selecting the starting monomer.

[0023] Fig.10 Shown is the formation of a charged macrocycle within a larger GOF prepared using a pre-functionalized 9H-carbazole-3,6-dicarbonitrile monomer bearing charged substituents on its ring nitrogen atoms.

[0024] Fig.11 Alternative schemes for forming neutral or negatively charged GOFs are shown.

[0025] Fig.12 A reaction scheme for functionalizing aromatic rings in GOFs with sulfonate groups is shown.

[0026] Fig.13 An alternative reaction scheme for functionalizing aromatic rings in GOFs with sulfonate groups is shown.

[0027] Fig.14 Another reaction scheme for the functionalization of aromatic rings in GOFs utilizing monomers comprising a combination of nitrile and acetyl groups on the same monomer or on two or more different monomers in a monomer mixture is shown.

[0028] Fig.15A and 15B The use of nitrile monomers ( Fig.15A ) or acetyl monomer ( Fig. 15B ) use charged dopant monomers to tune the average pore size and charge density of GOFs.

[0029] Fig.16 The use of a bilayer self-supporting membrane comprising a first layer of GOF having a relatively large average pore size adjacent to and covalently cross-linked with a second layer of GOF having a smaller average pore size is shown.

[0030] Fig.17 A bipolar GOFIM (bp-GOFIM) comprising an anion-exchange layer (AEL) composed of anion-conducting GOFIM (a-GOFIM) and a cation-exchange layer (CEL) composed of cation-conducting GOFIM (c-COFIM) with a water-dissociation catalyst sandwiched at the interface is shown.

[0031] Fig.18 is a schematic diagram of one embodiment of an aqueous organic redox flow battery (AORFB) including an ion-selective membrane.

[0032] Fig.19 Shown are the ionic conductivity of neutral GOFIM (n-GOFIM) in different electrolytes measured using impedance spectroscopy.

[0033] Fig. 20 A comparison of the battery cycling performance of GOFIM and commercial Daramic separators applied in non-aqueous organic redox flow batteries is shown. DETAILED DESCRIPTION

[0034] GOFIMs, devices incorporating GOFIMs, and methods of making GOFIMs are provided.

[0035] GOFIMs can be synthesized from monomers containing nitrile and / or acetyl groups using a simple, thermally controlled, stepwise nitrile and / or acetyl trimerization and membrane casting technique. The choice of monomers and the choice of functionalizing the membrane with charged functional groups provide control over the membrane pore size, pore surface polarity, and charge density. As a result, the membrane ion selectivity and ion conductivity can be tailored for specific applications, including applications requiring nanopores with high ion selectivity. As an illustration, membranes with average pore sizes ranging from 0.1-5 nm, including 0.5-2 nm, can be synthesized.

[0036] GOFIM can be used in any device and application that relies on size and / or charge selective passage of ions. Such devices and applications include electrochemical cells, electrocatalytic cells, desalination cells, purification and recovery units based on ion separation, water splitting, and chemical processes such as catalysis. The membrane is particularly suitable for electrochemical cells, such as aqueous or non-aqueous redox flow batteries, where minimizing or eliminating electrolyte crossover is important.

[0037] GOFIMs consist of an amorphous (or "glassy") organic framework containing a network of covalently bonded aromatic rings. The aromatic rings forming the network include phenylene rings, 1,3,5-triazine rings, pyridine rings, pyrimidine rings, or a combination of two or more thereof. The membrane may comprise a single layer of GOF, or may comprise two or more layers of different GOFs with covalent bonds between adjacent layers.

[0038] Compared to crystalline covalent organic frameworks, which are usually provided on a supporting substrate in the form of a powder or a powder-based coating, GOF is solution processable and can easily form a continuous, monolithic sheet of GOF, wherein the sheet has a uniform chemical composition. Therefore, the membrane prepared according to the method described herein can be distinguished from a membrane composed of conjugated polymer particles dispersed in a polymer binder because such a membrane has a non-uniform chemical composition. In addition, GOF can be made in the form of a self-supporting membrane. As used herein, the term self-supporting membrane refers to a continuous monolithic sheet of material that does not require a supporting substrate to maintain its continuous monolithic structure and exists as a continuous monolithic sheet without a supporting substrate, or can be removed from a supporting substrate and processed as a continuous monolithic sheet. Therefore, the self-supporting ion-conducting membranes described herein are easily distinguished from a coating supported by a substrate composed of a crystalline powder. It should be noted that although ion-conducting membranes can be formed as self-supporting membranes, they can also be formed as GOF sheets on a supporting substrate.

[0039] In the network, the aromatic rings are covalently bonded in a disordered structure, where the aromatic rings may be covalently bonded directly to each other, or may be covalently bonded to each other through bonding groups, such as alkane chains, alkene chains, and / or through carbazole groups. Alkane chains and alkene chains are typically short chains containing from one to ten carbon atoms in the chain. This includes alkane and alkene chains containing from one to six carbon atoms, and also includes alkane and alkene chains containing from one to three carbon atoms in the chain. However, longer alkane and alkene chains may be used. The amorphous nature of GOF is shown in Figure 1 , which shows an example of a GOF formed from covalently bonded phenylene groups.

[0040] The ring atoms of the aromatic ring, the bonding groups connecting the aromatic rings, or both can be functionalized with anionic or cationic substituents to provide an ion-conducting membrane with charge selectivity. Examples of anionic substituents that can functionalize the aromatic rings and / or bonding groups include sulfonate groups, phosphonate groups, and carbonate groups. Examples of cationic substituents that can functionalize the aromatic rings and / or bonding groups include quaternary ammonium groups and cationic nitrogen-containing heteroaromatic groups. Cationic charge can also be introduced into the GOF by alkylating the ring nitrogen atoms of the nitrogen-containing aromatic rings (e.g., the nitrogen atoms of the pyridine ring or pyrimidine ring) to convert the nitrogen-containing aromatic rings into cationic aromatic groups.

[0041] GOF can be made from various nitrile monomers having two or more nitrile groups, acetyl monomers having two or more acetyl groups, mixed monomers having at least one nitrile group and at least one acetyl group in the same monomer, or a combination thereof. Examples of nitrile monomers include alkane dinitrile, 2,4,6-tricyano-1,3,5-triazine, 1,3,5-tricyanobenzene, succinonitrile, perfluoroterephthalonitrile, perchloroterephthalonitrile, 1,2,3-propanetricarbonitrile, 2-methylglutaronitrile, 3,3-bis(cyanomethyl)glutaronitrile, 1,4-benzodicarbonitrile, [1,1'-biphenyl]-4,4'-dicarbonitrile, 1,4-benzodiacetonitrile, 2,2'-([1,1'-biphenyl]-4,4'-diyl)diacetonitrile and 9H-carbazole-3,6-dicarbonitrile, the structures of which are shown in Figure 2 Other examples include aromatic nitrile monomers containing multiple phenylene rings, at least some of which are linked by ether groups, and at least some of which have fluorine substituents on the phenylene rings, such as Figure 3 As shown in the example.

[0042] Acetyl monomers include aliphatic ketones having two or more carbonyl groups, including alicyclic ketones. Examples of these include alkanediones such as butanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 1,4-cyclohexanedione, 1,3-cyclohexanedione, 1,3,5-cyclohexanetrione, 1,3-cyclopentanetrione, 2,6- and diacetylpyridine, 1-(1,4-phenylene)diethyl ketone, 4-acetoxy-4'-acetylbiphenyl and 1,3,5-triacetylbenzene, and structures such as Figure 4 As shown. Figure 4 As shown, in some embodiments of the cycloaliphatic acetyl monomer, the ring has one or more alkyl (eg, methyl) substituents.

[0043] The mixed acetonitrile monomers including at least one acetyl group and at least one nitrile group include 4-acetylbenzonitrile and acetonitrile, and the structure thereof is as follows: Figure 5 shown.

[0044] In addition to nitrile monomers, acetyl monomers and mixed acetonitrile monomers, monomers having only one acetyl group without any nitrile group, or monomers having only one nitrile group without any acetyl group, can also be used in the synthesis of GOF. These monoacetyl or mononitrile monomers are used as dopants to introduce functional groups (including charged functional groups) into the network of covalently bonded aromatic rings in order to customize the pore size within the GOF and / or customize the flexibility of the diaphragm. Mononitrile monomers include alkylnitrile monomers in which the alkyl group has anionic substituents, arylnitrile monomers in which the aryl group has anionic substituents, and cyanopyridinium monomers (e.g., 1-methyl-4-cyanopyridinium). Examples of mononitrile monomers are shown in Fig. 6AThe monoacetyl monomers include acetyl monomers in which the alkyl group has an anionic substituent, aryl monomers in which the aryl group has an anionic substituent, and acetylpyridinium monomers (e.g., 1-methyl-4-acetylpyridinium). Examples of the monoacetyl monomers are shown in Figure 6B In. (In Fig. 6A and 6B In the formula (A), “M” represents a charge-balancing cation, such as a metal ion).

[0045] A stepwise condensation reaction involving soluble intermediates is used to synthesize a network of covalently bonded aromatic groups from monomers. The reaction trimerizes monomers containing nitrile and acetyl groups to form rings of phenylene, triazine, pyridine and / or pyrimidine that form the backbone of the network. The stepwise condensation reaction scheme is schematically shown in Figure 7 In. The synthesis uses an organic solution 702, which contains a nitrile monomer having at least two nitrile groups, an acetyl monomer having at least two acetyl groups, a mixed monomer comprising at least one nitrile group and at least one acetyl group, or a combination of two or more such monomers, wherein the monomers are dissolved in a trimerization catalyst. In the first step of the synthesis, a solution is formed, and the nitrile and / or acetyl groups of the monomers in the solution are dimerized to form a soluble intermediate. Mixing can be used to promote these first condensation reactions. The first condensation step is performed at a first temperature. The first temperature can be room temperature (RT) (e.g., a temperature in the range of 21° C. to 24° C.) or can be a temperature increased to greater than room temperature. For example, a temperature of up to 100° C. can be used. The solution 702 is coated on a substrate 704 and spread into a viscous liquid film 706. The intermediate then undergoes a further condensation reaction, in which the monomers are trimerized to form a network of fused aromatic rings, thereby converting the viscous liquid film 706 into a self-supporting membrane 708 containing GOF. Figure 7 A portion of the covalent network structure of the GOF forming the macrocycle is shown in the reaction scheme on the right, and a larger amorphous structure of the GOF into which the macrocycle is introduced is also schematically shown on the right. Therefore, it should be understood that the GOF does not have a highly ordered crystalline structure, and although the macrocycle can be formed in the covalently bonded network, not all aromatic rings will be introduced into the well-ordered macrocycle. Further condensation reactions are generally carried out at a temperature higher than that at which the initial condensation is carried out. As an illustration, the second condensation step can be carried out at a temperature ranging from room temperature to 200°C, however, higher or lower temperatures can also be used, depending on the selected monomers and the desired reaction progress rate. The self-supporting membrane 708 can then be washed to remove the trimerization catalyst and peeled off from the substrate 704. Suitable trimerization catalysts include, but are not limited to, Bronsted acids, such as trifluoromethanesulfonic acid, methanesulfonic acid, ethanesulfonic acid (i.e., R-SO3H) and Lewis acid ionic liquids.

[0046] Stepwise condensation can be carried out with a single monomer or various monomer combinations including Figure 2 , 3, 4, 5, 6A and 6B to form a membrane having a desired pore size, pore surface polarity, charge state and / or charge density. Figure 8 The macrocycles formed within the larger GOF are shown to illustrate the ability to tune the average pore size in neutral (uncharged) GOFs by choice of starting monomers. Fig. 9 The macrocycle formed within a larger GOF is shown to illustrate the ability to tune the pore surface polarity in a neutral GOF by selecting the starting monomer.

[0047] The charge state and charge density of charged GOFs can be tailored by introducing pre-functionalized monomers with cationic or anionic groups into GOFs or by post-functionalizing preformed GOFs with charged groups. Fig.10 The charged macrocycle formed in a larger GOF prepared using a pre-functionalized 9H-carbazole-3,6-dicarbonitrile monomer having a charged substituent on its ring nitrogen atom is shown. The pre-functionalized 9H-carbazole-3,6-dicarbonitrile monomer is for illustrative purposes only. Other nitrile and acetyl monomers pre-functionalized with charged substituents may be used, including monomers with pyridine or bipyridinium groups. These include 2,6-pyridinium dicarbonitrile and 2,2'-bipyridinium-5,5' dicarbonitrile ( Fig.10 , illustration). Fig.10 In the formula (a), R is used to represent a general anionic or cationic group. Examples of suitable anionic groups include sulfonate groups, phosphonate groups and carbonate groups.

[0048] Fig.11 An alternative scheme for forming a GOF containing neutral or negative charges is shown. The scheme starts with a halogenated (e.g., fluorinated or chlorinated) aromatic nitrile monomer having at least two nitrile groups. A nucleophilic aromatic substitution reaction is performed between the halogenated aromatic monomer and a thiol compound to form a thiolated aromatic monomer having at least two nitrile functional groups. A stepwise condensation reaction is then performed to form a fused aromatic ring network. Fig.11 In the figure, M in the product on the right represents a charge-balancing counterion, such as a metal ion. The nature of the functional group on the thiolated monomer depends on the specific thiol compound used. Two exemplary thiolated monomers are shown in the figure, where M in the thiolated monomer on the right represents a charge-balancing counterion, such as a metal ion.

[0049] Fig.12 A reaction scheme for post-synthetic functionalization of aromatic rings in GOFs with sulfonate groups is shown. In this scheme, the benzene rings in a GOF containing a network of covalently bonded phenylene rings are sulfonated and subsequently deprotonated. (As in the previous figure, M represents a charge-balancing cation)

[0050] Fig.13An alternative reaction scheme for post-synthetic functionalization of aromatic rings in GOFs with sulfonate groups is shown. In this scheme, the benzene rings in a GOF containing a network of covalently bonded phenylene rings are chloromethylated, and the chloromethyl groups on the rings are subsequently reacted with a tertiary amine to convert the chloromethyl groups into quaternary ammonium groups.

[0051] Yet another reaction scheme for post-synthetic functionalization of aromatic rings in GOFs utilizes monomers that include a combination of nitrile and acetyl groups on the same monomer or on two or more different monomers in a monomer mixture. This scheme is shown in Fig.14 .exist Fig.14 In an illustrative embodiment of , 4-acetylbenzonitrile monomer, acetyl cyanide monomer, or a mixture thereof, or a mixture of 1,4-phthalonitrile and 1-(1,4-phenylene)bis-ethyl ketone is used to form a network of covalently bonded phenylene, pyridine, pyrimidine, and triazine rings (left panel). Unlike GOFs in which the different aromatic rings are distributed in a certain pattern within the covalently bonded network (e.g., ABABAB or ABBABBA), the different aromatic rings in the covalently bonded network made from mixed monomers can be randomly distributed. A portion of the network forming the macrocycle is depicted in the figure, illustrating the random distribution of phenylene, pyridine, and pyrimidine rings (center panel). The nitrogen atoms of the aromatic rings in the network can then be post-functionalized using various reaction schemes. For example, the ring nitrogen atoms of the pyridine, pyrimidine, and / or triazine rings can be reacted with sulfuric acid or phosphoric acid to convert the nitrogen-containing heteroaromatic rings into cations associated with sulfate or phosphate anions. Thus, as Fig.14 As shown in the upper right figure of , pyridinium dihydrogen phosphate groups and / or pyrimidinium dihydrogen phosphate groups can be introduced into GOF. Similarly, pyridinium hydrogen sulfate groups and / or pyrimidinium hydrogen sulfate groups can be introduced into GOF. Alternatively, the nitrogen atoms of the aromatic rings in the network can be post-functionalized via an alkylation (e.g., methylation) reaction (middle right figure). Fig.14 The lower right figure shows another option for post-functionalization of GOF. In this scheme, the nitrogen atoms of the aromatic rings in the network react with cyclic sulfates, cyclic phosphates and / or cyclic carbonates to functionalize the aromatic rings with sulfonate, phosphonate or carbonate groups. It should be understood that other than Fig.14 Mixed monomers other than those shown, and GOFs prepared using other types of monomers can be prepared Fig.14 The post-functionalization reaction shown is provided that the GOF comprises a heterocyclic nitrogen-containing heteroaromatic compound.

[0052] Fig.15A and 15B The use of charged dopant monomers to tune the average pore size and charge density of GOFs was demonstrated in Fig.15A ) or acetyl monomer ( Fig. 15B). In this figure, a general monomer with two nitrile groups or two acetyl groups is shown at the top, and the main body of the monomer is represented by a gray box. As in the previous figure, R is used to represent a general anionic or cationic group. Examples of suitable anionic groups include sulfonate groups, phosphonate groups and carbonate groups, and suitable cationic groups include quaternary ammonium groups and cationic nitrogen-containing heteroaromatic groups.

[0053] The self-supporting GOFIM may comprise a single layer of GOF or may comprise two or more layers of different GOFs. The multilayer membrane may be formed by a stepwise condensation of a second GOF to a previously formed layer comprising a GOF. The stepwise condensation reaction facilitates the manufacture of a stable multilayer membrane because crosslinking occurs between adjacent layers of GOF within the membrane, which stabilizes the layers against delamination. The use of multilayer GOFs is advantageous because it allows the overall properties of the self-supporting multilayer membrane to be adjusted by combining GOFs having different properties. Fig.16 The use of a double-layer self-supporting GOFIM is shown, which includes a first layer of GOF with a relatively large average pore size, which is adjacent to and covalently cross-linked with a second layer of GOF with a smaller average pore size. In this double-layer design, the first layer provides fast ion conduction and mechanical stability, while the second layer provides high ion selectivity.

[0054] In other embodiments of the multilayer structure, the GOF layers are separated by an intermediate layer that is not a GOF. The nature of the intermediate layer will depend on the intended application. For example, by pairing a cationic GOFIM (c-GOFIM) with an anionic GOFIM (a-GOFIM) in a multilayer structure, a bipolar GOFIM (bp-GOFIM) structure can be constructed. As an illustration, Fig.17 As schematically shown in , the bp-GOFIM structure may include c-GOFIM and a-GOFIM separated by a layer comprising a water dissociation catalyst material. This membrane design may be used, for example, as a bipolar membrane in an electrochemical cell for water splitting. Such a cell may be fabricated by laminating a self-supporting a-GOFIM (i.e., as an anion exchange layer; AEL) onto one surface of a water dissociation catalyst layer, and laminating a self-supporting c-GOFIM (i.e., as a cation exchange layer; CEL) onto the opposite surface of the catalyst layer.

[0055] Although the membranes described herein can be made and used in a self-supporting form, they can also be incorporated into a composite membrane comprising one or more layers of GOF on a substrate, wherein the nature and purpose of the substrate will depend on the intended application. Typically, the substrate itself is a porous layer, such as a large porous layer. Examples of substrates include carbon fiber paper, glass fiber mats, porous polymer layers, such as porous polyolefins (e.g., polypropylene or polyethylene)), porous polyethylene terephthalate, porous polyimides (including partially carbonized porous polyimides), or porous polyacrylonitrile layers, porous alumina, and graphene or graphene oxide layers.

[0056] Self-supporting GOFIM and composite GOFIM have applications in a variety of different devices, where ions are separated or excluded based on their size and / or charge. Such devices include electrochemical and non-electrochemical ion separation devices. In these devices, GOFIM can be set at any interface where it is desired to selectively pass through or exclude certain ions based on their size and / or charge. If the device has more than one such interface, the device can include GOFIM at one, some or all of the interfaces. In an electrochemical cell, such an interface will include an interface between two different electrolyte solutions or an interface between a solid electrode surface and an electrolyte solution. The electrolyte solution will include at least one ion, and will typically include more than one ion. The ions can be redox-active ions (i.e., anions and / or cations that undergo oxidation and / or reduction reactions during operation of the electrochemical cell), non-redox-active ions, or charge-balancing ions.

[0057] In some embodiments of the device, the GOFIM separates the anolyte solution and the cathode electrolyte solution in the electrochemical device. The basic components of such an electrochemical device include an anode, an anolyte in contact with the anode, a cathode, a cathode electrolyte in contact with the cathode, a GOFIM of the type described herein that separates the anolyte and the cathode electrolyte, and an external wire or circuit that connects the anode to the cathode. The electrochemical unit incorporating the GOFIM is characterized by a long life with minimal capacity fading and high energy efficiency.

[0058] Fig.18 One embodiment of an AORFB including a GOFIM is schematically shown. In an AORFB, redox-active chemicals are dissolved in an aqueous supporting electrolyte solution, where they serve as anode and cathode electrolytes. These anode and cathode electrolytes (which are referred to as anolyte and cathode electrolyte, respectively) may be contained in an anode cell compartment 1802 and a cathode cell compartment 1804. For simplicity, Fig.18, the anode electrolyte is generally represented as "B", the cathode electrolyte is generally represented as "A", the charges of the anode electrolyte in its oxidized and reduced states are represented as m+ and (my)+, respectively, and the charges of the cathode electrolyte in its oxidized and reduced states are represented as (n+x)+ and n+, respectively. GOFIM 1806 separates the anode unit compartment 1802 from the cathode unit compartment 1804.

[0059] During the charge-discharge process, the redox-active anolyte and cathode electrolyte are stored in the anolyte reservoir 1808 and cathode electrolyte reservoir 1810, respectively. The reservoirs 1808 and 1810 are in fluid communication with their respective unit compartments 1802 and 1804 so that the anolyte and cathode electrolyte can be circulated through the unit compartments. This circulation can be accomplished using, for example, a pump 1811. During the charging process, a bias voltage is applied across the anode 1812 in the anode unit compartment 1802 and the cathode 1814 in the cathode unit compartment 1804. Fig.18 As shown, the anode current collector 1815 and the cathode current collector 1817 can be used to provide electrical conduction between the electrodes and the external circuit. During the charging process, when the anode electrolyte passes through the anode 1812, the anode electrolyte molecules undergo an electrochemical reduction reaction, while the cathode electrolyte molecules passing through the cathode 1814 undergo an electrochemical oxidation reaction. During the discharge process, the anode electrolyte molecules undergo an electrochemical oxidation reaction, while the cathode electrolyte molecules passing through the cathode 1814 undergo an electrochemical reduction reaction, thereby supplying power to the load connected between the anode 1812 and the cathode 1814.

[0060] A variety of redox species can be used as anolyte and cathode electrolyte. These include redox active organic substances, metals and metal ions, metal-organic complexes, redox active gases and other redox active inorganic substances. Specific examples include, but are not limited to, phenazine, phenothiazine, fluorenone, naphthalene diamine, viologen, sulfide, 2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO), TEMPO derivatives, ferrocene, ferrocyanide, alloxazine molecules, iron, bromide, iodide, vanadium, zinc, nicotinamide-adenine-dinucleotide phosphate (NADP), radia lene, water (e.g., in hydrogen evolution reaction (HER) or oxygen evolution reaction (OER)), lithium, sodium, potassium and aluminum.

[0061] Viologen derivatives, such as bis(3-trimethylammonio)propyl viologen tetrachloride, and other pyridyl derivatives, such as those described in U.S. Provisional Patent Application Serial No. 63 / 183,162 and shown in FIG. 32 (“Dex-Vi”) of U.S. Provisional Patent Application Serial No. 63 / 183,162, are particularly attractive for AORFBs operating at or near pH neutral conditions because they have redox potentials close to the thermodynamic hydrogen evolution reaction potential of water (-0.41 V relative to SHE). Thus, because TEMPO oligomers having redox potentials at or near the thermodynamic oxygen evolution reaction potential of water (0.82 relative to SHE) can be prepared using the methods described herein, pairing TEMPO oligomers with pyridyl derivatives allows one to exploit the full electrochemical potential window of AORFBs.

[0062] The supporting electrolyte solution typically includes a chemical (eg, a salt) that is not electroactive in the applied potential range of the AORFB but has a high ionic strength and thus contributes to the conductivity of the solution. Common supporting electrolytes include sodium chloride (NaCl) and potassium hydroxide (KOH).

[0063] Example

[0064] Example 1: Formation of self-supporting GOFIM from mixed nitrile / acetyl monomers.

[0065] 1 mL amount of CF3SO3H (trifluoromethanesulfonic acid; trimerization catalyst) was added to 0.15 g of 4-acetylbenzonitrile under stirring at room temperature. The viscous solution was stirred for 0.5 hours and then drop-cast onto a plain, pre-cleaned glass and spread into a thin film. The glass was then placed on a hot plate preheated to 120°C for 30 minutes. A flexible, self-supporting membrane was successfully formed on the glass surface. The membrane was then quenched in cold water and immersed in water to release the membrane. The self-supporting membrane was immersed in a 0.1 M NaOH solution overnight to remove excess CF3SO3H. After washing the membrane with water and ethanol several times, the membrane was stored in deionized (DI) water for further use.

[0066] Example 2: Ionic conductivity and electrochemical performance of self-supporting GOFIM.

[0067] n-GOFIM preparation:

[0068] A 1 mL amount of CF3SO3H was added to 0.1 g of 4,4-biphenyldicarbonitrile at 0°C with vigorous stirring. The viscous solution was then stirred for 40 minutes and subsequently drop-cast onto a common pre-cleaned Petri dish where the solution was spread into a thin layer. The Petri dish was then sealed with Teflon tape and left to stand for 0.5 hours before the diaphragm was quenched in water and soaked in 0.5 M NaOH for 24 hours to remove the CF3SO3H. After washing the diaphragm with water and ethanol several times, the diaphragm was stored in acetonitrile for further use.

[0069] Flow battery conditions:

[0070] A redox flow battery was constructed using 0.1 M viologen trimer and 0.1 M ferrocene trimer in acetonitrile with LiTFSI as the supporting salt. The results showed that n-GOFIM has comparable cycling stability and efficiency to conventional Daramic separators under the same electrolyte conditions.

[0071] Electrochemical Impedance Spectroscopy:

[0072] c-GOFIM membranes with different percentages of charge dopants were prepared. The ion migration resistance of the membranes was measured using a shrinkage test with aqueous NaCl and H2SO4 electrolytes, respectively.

[0073] Example 3: Synthesis and characterization of self-supporting c-GOFIM.

[0074] Synthesis of acetyl methanesulfonate:

[0075]

[0076] 31.4 g of sodium sulfite and 20 mL of chloroethyl ketone (equimolar ratio) were added to 100 mL of water. Then, the mixture was refluxed for 24 hours. After cooling to room temperature, the residual solvent was evaporated on a rotary evaporator. The white reaction product was dissolved in 250 mL of ethanol at 60 ° C and filtered to remove salt. The solution was evaporated again and dried in a vacuum oven at room temperature.

[0077] Synthesis of cyanomethanesulfonic acid:

[0078]

[0079] 10 mL of chloroacetonitrile and 19.66 g of sodium sulfite (equimolar ratio) were added to 200 mL of water. The mixture was then refluxed for 24 hours. After cooling to room temperature, the residual solvent was evaporated on a rotary evaporator.

[0080] Preparation of self-supporting GOFIM:

[0081] At room temperature, under vigorous stirring, 1 mL of CF3SO3H was added to 0.2 g of 1,4-dicyanobenzene. The viscous solution was stirred for 20 minutes, then drop-cast onto a common pre-cleaned petri dish and spread into a thin layer. The petri dish was then sealed with Teflon tape and left to stand for 72 hours. The diaphragm was then quenched in water and soaked in 0.5 M NaOH for 24 hours to remove CF3SO3H. After washing the diaphragm with water and ethanol several times, the diaphragm was stored in deionized (DI) water for further use.

[0082] Preparation of composite n-GOFIM:

[0083] First, the monomer 1,4-diacetylbenzene (120 mg) was dissolved in 1 mL of CF3SO3H to form a homogeneous solution. A glass fiber (Celgard or porous polyimide) was attached to a micro coverslip, and then the solution was drop-cast onto the glass fiber and clamped with another micro coverslip. The sandwich system was heated at 120°C for 12 hours. After cooling to room temperature, the composite GOFIM was separated from the coverslip by immersion in DI water. The membrane was then quenched in water and soaked in 0.5 M NaOH for 24 hours to remove CF3SO3H. After washing the composite GOFIM three times with water and ethanol, the membrane was stored in DI water for further use.

[0084] Preparation of c-GOFIM:

[0085] 0.2 g of acetyl methanesulfonate and 1,4-dicyanobenzene mixture (5 and 10 wt%) was used as a precursor for the synthesis of sulfonate functionalized GOF. The viscous solution was stirred for 30 and 50 minutes, respectively. The subsequent process was the same as that used to synthesize GOFIM from the original 1,4-dicyanobenzene monomer. A more flexible GOFIM was obtained.

[0086] Ionic conductivity:

[0087] The ionic conductivity of GOFIM was measured using electrochemical impedance spectroscopy. The membrane was soaked in 4M NaCl or 2M H2SO4 for 24 hours before measurement. The membrane was sandwiched between stainless steel electrodes. The ionic conductivity was calculated by the following equation: σ = L / (R m ×A), where R m is the diaphragm resistance, A is the active diaphragm area (2cm 2 ), and L is the thickness of the separator. The results are shown in the table below.

[0088]

[0089] The word "illustrative" is used herein to mean used as an example, instance, or illustration. Any aspect or design described herein as "illustrative" is not necessarily to be construed as being preferred or advantageous over other aspects or designs. In addition, for the purposes of this disclosure and unless otherwise specified, "a" or "an" (many not translated in the text) may mean only one, or may mean "one or more". Embodiments consistent with either interpretation are contemplated.

[0090] For the purpose of illustration and description, the above description of illustrative embodiments of the present invention has been given. It is not exhaustive, nor is it intended to limit the present invention to the precise form disclosed, and modifications and variations may be made in accordance with the above teachings, or modifications and variations may be obtained from the practice of the present invention. These embodiments are selected and described to explain the principles of the present invention, and as a practical application of the present invention, so that those skilled in the art can utilize the present invention in various embodiments, and with various modifications suitable for the specific purpose envisioned. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An electrochemical cell comprising: (a) anode; (b) a first electrolyte solution comprising redox-inactive ions, redox-active ions, or a mixture thereof; (c) cathode; (d) a second electrolyte solution comprising redox-inactive ions, redox-active ions, or a mixture thereof; and (e) at least one ion-conducting membrane comprising a continuous, integral, uniform sheet of a glassy organic framework, wherein the at least one ion-conducting membrane separates (a) and (b), separates (b) and (d), or separates (c) and (d), wherein the glassy organic framework comprises a network of covalently bonded aromatic rings, wherein the aromatic rings comprise phenylene rings, 1,3,5-triazine rings, pyridine rings, pyrimidine rings, or a combination of two or more thereof.

2. The electrochemical cell of claim 1, wherein the ion-conducting membrane is a self-supporting membrane.

3. The electrochemical cell of claim 1, wherein said ion-conducting membrane is a composite membrane comprising said continuous, integral, uniform sheet of said glassy organic framework on a substrate.

4. The electrochemical cell of claim 1, wherein the aromatic ring is functionalized with one or more cationic groups.

5. The electrochemical cell of claim 1, wherein the aromatic ring is functionalized with one or more anionic groups.

6. The electrochemical cell of claim 1, wherein the aromatic ring is functionalized with one or more halogen atoms.

7. The electrochemical cell of claim 1, wherein the aromatic ring comprises a phenylene ring.

8. The electrochemical cell of claim 7, wherein the phenylene rings are directly covalently bonded to each other.

9. The electrochemical cell of claim 7, wherein the phenylene rings are covalently bonded to each other via an alkane chain or an alkene chain.

10. The electrochemical cell of claim 1, wherein the aromatic ring comprises a 1,3,5-triazine ring.

11. The electrochemical cell of claim 10, wherein the 1,3,5-triazine rings are directly covalently bonded to each other.

12. The electrochemical cell according to claim 10, wherein the 1,3,5-triazine rings are covalently bonded to each other via an alkane chain or an alkene chain.

13. The electrochemical cell according to claim 10, wherein the 1,3,5-triazine rings are covalently bonded to each other via a carbazole group, a pyridinium group or a bipyridinium group.

14. The electrochemical cell of claim 1, wherein the aromatic ring comprises a phenylene ring and a 1,3,5-triazine ring.

15. The electrochemical cell according to claim 14, wherein the phenylene group and the 1,3,5-triazine ring are directly covalently bonded to each other.

16. The electrochemical cell of claim 1, wherein the first electrolyte solution and the second electrolyte solution are aqueous solutions.

17. The electrochemical cell of claim 1, wherein the first electrolyte solution is an anolyte solution comprising one or more redox-active anolytes, and the second electrolyte solution is a catholyte solution comprising one or more redox-active catholytes.

18. The electrochemical cell of claim 17, wherein said at least one ion-conducting membrane separates said anolyte solution from said catholyte solution.

19. The electrochemical cell of claim 17, wherein the electrochemical cell is an aqueous organic redox flow battery.

20. A method for preparing an ion-conducting membrane, the method comprising: dissolving monomers in a trimerization catalyst to form a solution, the monomers comprising: a nitrile monomer having one or more nitrile groups; an acetyl monomer having one or more acetyl groups; a monomer having at least one nitrile group and at least one acetyl group; a nitrogen-containing aromatic heterocyclic monomer comprising functional groups on a ring nitrogen atom in addition to at least two nitrile functional groups; or a combination of two or more thereof, and optionally, a charged monofunctional dopant monomer comprising a single nitrile group or a single acetyl group, wherein the monomers react to form an intermediate dissolved in the solution; forming a film of the solution on a surface of a substrate; as well as The membrane is heated to initiate reaction of the intermediates, thereby forming the ion-conducting membrane comprising a continuous, monolithic, uniform sheet of a glassy organic framework comprising a network of covalently bonded phenylene rings, 1,3,5-triazine rings, pyridine rings, pyrimidine rings, or combinations thereof.

21. The method of claim 20, further comprising releasing the ion-conducting membrane from the surface of the substrate to form a self-supporting ion-conducting membrane.

22. The method of claim 20, wherein the monomer comprises: Alkanedinitrile, 2,4,6-tricyano-1,3,5-triazine, 1,3,5-tricyanobenzene, succinonitrile, perfluoroterephthalonitrile, perchloroterephthalonitrile, 4,4'-((perfluoronaphthalene-2,6-diyl)bis(oxy))dibenzonitrile, 1,2-diketone, 1,3-diketone, 1,3-cyclohexanedione, 1,4-cyclohexanedione, 1,3,5-cyclohexanetrione, 1,3-cyclopentanetrione, 2,6-diacetylpyridine, or a combination of two or more thereof.

23. The method of claim 20, wherein the monomer comprises a nitrile monomer, an acetyl monomer, or a combination thereof, and a charged monofunctional dopant monomer.

24. The method of claim 20, wherein the monomer comprises a nitrogen-containing aromatic heterocyclic monomer.

25. A method for preparing an ion-conducting membrane, the method comprising: performing a nucleophilic aromatic substitution reaction between a halogenated aromatic monomer having at least two nitrile functional groups and a thiol compound to form a thiolated aromatic monomer having at least two nitrile functional groups; dissolving the thiolated aromatic monomer in a trimerization catalyst to form a solution, wherein the thiolated aromatic monomer reacts to form an intermediate soluble in the solution; forming a film of the solution on a surface of a substrate; as well as The film is heated to initiate the reaction of the intermediates to form a membrane comprising a sheet of a glassy organic framework comprising a thiolated network of covalently bonded 1,3,5-triazine rings.

26. A method for preparing a charged ion conducting membrane, the method comprising: Sulfonation of phenyl rings in an amorphous organic framework comprising a network of covalently bonded phenylene rings; as well as The sulfonate group is deprotonated.

27. A method for preparing a charged ion conducting membrane, the method comprising: Chloromethylation of phenyl rings in an amorphous organic framework comprising a network of covalently bonded phenylene rings; as well as The chloromethyl group is reacted with a tertiary amine to convert the chloromethyl group into a quaternary ammonium group.

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