KR101648844B1 - Seperator membrane made of ion-conducting polymer comprising phenyl pendant substituted with at least two sulfonated aromatic groups and redox flow batteries comprising the same - Google Patents

Abstract

The present invention relates to a separation membrane fabricated from an ion conductive polymer comprising phenyl pendant substituted with two or more sulfonated aromatic groups, and a redox flow battery having the separation membrane.
The separation membrane prepared from the ion conductive polymer containing phenyl pendant substituted with two or more sulphonated aromatic groups according to the present invention can provide excellent ion conductivity, mechanical strength and chemical stability. Further, the redox flow battery having the separation membrane according to the present invention can exhibit excellent cell performance even when it is repeatedly charged / discharged dozens of times, and can maintain a high discharge charge retention ratio.

Description

TECHNICAL FIELD [0001] The present invention relates to a separator made of an ion conductive polymer comprising a phenylpentane substituted with at least two sulfonated aromatic groups, and a redox flow cell comprising the ion conductive polymer. redox flow < / RTI >

The present invention relates to a separation membrane fabricated from an ion conductive polymer comprising phenyl pendant substituted with two or more sulfonated aromatic groups, and a redox flow battery having the separation membrane.

Efforts are being made to save fossil fuels or to apply renewable energy to more fields by improving the use efficiency to solve problems of depletion of fossil fuels and environmental pollution. Renewable energy sources such as solar and wind power have been used more efficiently than before, but these energy sources are intermittent and unpredictable. Due to these characteristics, dependence on these energy sources is limited, and the ratio of renewable energy sources among the primary power sources is very low.

BACKGROUND ART Rechargeable batteries provide a simple and efficient method of storing electric power, so that they have been miniaturized to increase their mobility, and efforts to utilize them as an intermittent auxiliary power source or a power source for a small household appliance such as a laptop, a tablet PC, and a mobile phone have been continued.

Redox Flow Battery (RFB) is a secondary battery that can store and store energy for a long time by repeated charging and discharging by electrochemical reversible reaction of electrolyte. The stack and electrolyte tanks, which depend on the capacity and output characteristics of the battery, are independent of each other, so that the battery design is free and the installation space is limited.

The redox flow battery has a load leveling function that can cope with the sudden increase in power demand installed in a power plant, a power system, or a building, and has a function to compensate or suppress the power failure or the instantaneous undervoltage. It is an energy storage technology and suitable for large-scale energy storage.

These redox flow cells consist of two separate electrolytes. One stores the electroactive material in the negative electrode reaction and the other stores the positive electrode reaction. In an actual redox flow cell, the electrolyte reaction is different between the positive electrode and the negative electrode, and there is a flow of the electrolytic solution, so a pressure difference occurs between the positive electrode and the negative electrode. The reaction of the positive and negative electrode electrolytes in the entire vanadium-based redox flow battery, which is a typical redox flow battery, is as follows.

Therefore, a separation membrane with improved physical and chemical durability is required to overcome the pressure difference between both electrodes and to exhibit excellent cell performance even when charging and discharging are repeated. However, there is a disadvantage that resistance increases due to an increase in the thickness of the separating film in order to improve the physical durability.

Accordingly, the present inventors have made intensive studies to find a separation membrane for a redox flow battery having improved ionic conductivity and physical and chemical durability. As a result, it has been found that when a multiphenyl pendant is introduced and a sulfonic acid group is substituted at its terminal, densely and locally, The ion-exchange membrane prepared from an ion-conducting polymer having improved chemical stability by constituting the polymer backbone with a carbon-carbon bond excluding an ether bond can induce an effective phase separation of a hydrophilic domain and a hydrophobic domain by forming a sulfonated structure, Strength and excellent ionic conductivity, and a redox flow battery comprising the same as a separation membrane was fabricated. It was confirmed that the battery had excellent medium / long-term durability while exhibiting excellent cell performance, and completed the present invention.

It is an object of the present invention to provide a separation membrane made from an ion conductive polymer containing phenyl pendant substituted with two or more sulfonated aromatic groups and a redox flow battery having the separation membrane.

A first aspect of the present invention provides an electrolyte membrane prepared from an ion conductive polymer having a skeleton containing a phenylene repeating unit represented by one or more of the following Formula 1 and at least one phenylene repeating unit represented by the following Formula 2:

[Chemical Formula 1]

(2)

In the above Formulas 1 and 2,

A ₁ and A ₂ is a single bond, each independently, - (C = O) - , - (P = O) -, - (SO 2) -, -CF 2 - or _{- (C (CF 3) 2} ) - ego;

B is -O-, -S-, - (SO ₂ ) -, - (C = O) -, -NH- or -NR ₁₅ -, wherein R ₁₅ is a C 1 to C 6 alkyl group;

At least two or all of R ₁ to R ₅ are a sulfonated phenyl, a sulfonated pyridinyl or a sulfonated naphthalenyl which is substituted with a sulfonic acid group or an alkali metal salt thereof, and R ₁ To R ₅ each independently represent a hydrogen atom (-H), a halogen atom (-X), a sulfonic acid group (-SO ₃ H), a phosphoric acid group (-PO ₃ H ₂ ), an acetic acid group (-CO ₂ H) (-NO ₂ ), a perfluoroalkyl group, a perfluoroalkylaryl group optionally containing one or more oxygen, nitrogen or sulfur atoms in its chain, a perfluoroaryl group and an -O-perfluoroaryl group, or one Or an aryl group substituted with at least one halogen, a sulfonic acid group, a phosphoric acid group, an acetic acid group or a nitro group, and the perfluoro group may include a substituent selected from the group consisting of sulfonic acid, phosphoric acid, acetic acid and nitro, , The phosphoric acid group and the acetic acid group are alkaline May be in the form of a metal salt;

Each of R ₆ to R ₉ may independently include a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a sulfonic acid group, a phosphoric acid group, an acetic acid group and a nitro group, and the sulfonic acid group, phosphoric acid group and acetic acid group may be in the form of an alkali metal salt ;

R ₁₀ to R ₁₄ each independently may contain a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a sulfonic acid group, a phosphoric acid group, an acetic acid group and a nitro group, and the sulfonic acid group, phosphoric acid group and acetic acid group may be in the form of an alkali metal salt Each of which is independently a hydrogen atom, at least one fluorine atom (F) (except when all are fluorine), an aryl group, a perfluoroalkyl group, optionally at least one oxygen, nitrogen and / A perfluoroalkylaryl group including a sulfur atom, a perfluoroaryl group and an -O-perfluoroaryl group;

a and b are each independently an integer of 0 or more and 10 or less.

A second aspect of the present invention provides a redox flow battery having the separation membrane according to the present invention.

Hereinafter, the present invention will be described in detail.

The term "redox flow battery" of the present invention means that an electrolyte containing an electroactive species flows through an electrochemical cell, which reversibly converts chemical energy into electricity, A rechargeable fuel cell, which is a type of flow cell, is a reversible fuel cell in which all electro-active components are dissolved in an electrolyte. Gravity feed systems are used, but mainly the additional electrolyte is stored externally, typically in a separate tank, and is pumped through the cells of the reactor. Flow cells can be quickly recharged by replacing the electrolyte solution (in a manner similar to replenishing the fuel tank of an internal combustion engine) while at the same time recovering the spent material for re-energization. In such a redox flow battery, the energy of the cell is determined by the electrolyte volume, for example, the tank size, and the power by the electrode size, for example, the reactor size, so that the energy is completely decoupled from the power similarly to other fuel cells.

Unlike other batteries, such a redox flow battery is an aqueous solution in which an electroactive species is not a solid, and a mechanism for storing energy by an oxidation / reduction reaction of ions in the anode 21 and the cathode 22 Respectively. The positive electrode electrolyte and the negative electrode electrolyte for causing the above-described reaction are stored in separate storage tanks (not shown), respectively, and are introduced into the cell housing 51 through the electrolyte inflow ports 31 and 41 formed in the cell housing 51 And has a circulation system that contacts the anode 21 and the cathode 22 to cause a reaction and then flows out through the respective electrolyte outlets 32 and 42. The battery is discharged by connecting an electric load to an external circuit including an electric load to allow a current to flow, and conversely, an external power source is connected to the battery to allow the electric current to flow. In general, a cathodic electrolyte is charged when the redox couple is oxidized to the higher of the two states, and is discharged when the redox is reduced to the lower state. In the negative electrode electrolyte solution, the opposite phenomenon appears.

As described above, most redox flow cells are composed of two separate electrolytes. One stores the electroactive material in the negative electrode reaction and the other stores the positive electrode reaction. At this time, the negative electrode is defined as the anode and the positive electrode is defined as the cathode in discharging to prevent confusion. The charge will be reversed. Fresh or used electrolytes can be circulated and stored in a single storage tank. Or the concentration of the electroactive material can be individually adjusted. An ion exchange membrane is used as a separator to prevent mixing of electroactive species which may cause chemical breakdown.

The term "separation membrane" of the present invention refers to an ion exchange membrane introduced to prevent mixing of electroactive species in the redox flow cell, and a common counter ion carrier ) Passes through the separation film. For example, in a bromine-polysulfide system in which Na ₂ S ₂ is converted to Na ₂ S ₄ at the anode and Br ₂ is converted to ₂ Br at the cathode, excess Na ⁺ ions at the anode to maintain electro- Lt; / RTI > Similarly, in a vanadium system where V ^{2 +} is oxidized to V ^{3 +} at the anode and V ^{5 +} is reduced to V ^{4 +} at the cathode, the hydronium ion (H ₃ O ⁺ ) is injected through the proton- And moves to the cathode.

In an actual redox flow cell, the electrolyte reaction is different between the positive electrode and the negative electrode, and there is a flow of the electrolytic solution, so a pressure difference occurs between the positive electrode and the negative electrode. Therefore, it is preferable that the separation membrane has excellent physical strength so as not to be broken by such a pressure difference.

The separating film of the present invention may contain a phenyl pendant substituted with two or more sulfonated aromatic groups Wherein the ion conductive polymer comprising a phenylpentane substituted with at least two sulfonated aromatic groups is a molecule having a skeleton containing two or more phenylene repeating units, And a polyphenyl pendant in which two or more sulfonated aromatic groups are substituted at the terminal of the phenylene repeating unit of the species. For example, the ion conductive polymer comprising the phenylpentane substituted with at least two sulfonated aromatic groups may contain at least one phenylene repeating unit represented by Formula 1 and at least one phenylene repeating unit represented by Formula 2 And the like.

The "multiphenyl pendant" may be a substituent comprising a plurality of phenyl groups. For example, a phenyl ring containing one or more substituted or unsubstituted phenyl, naphthalene or heteroatom in one phenyl ring may be a further substituted bulky substituent.

The sulfuric acid group (-SO ₃ H) is introduced to impart proton (H ⁺ ) conductivity. Alkali metal salts of sulfonic acids may be used for the same purpose. The alkali metal salt may be such that a cation of an alkali metal such as Na, K or Li replaces a proton of a sulfonic acid.

On the other hand, the aromatic rings formed on the side chains have higher sulfonation reactivity than the aromatic rings forming the main chain skeleton. Therefore, the phenyl group at the end of the side chain among the phenylene repeating units has five substitution sites, so that up to five sulfonic acid groups or their alkali metal salts can be introduced. Rather than directly introducing a sulfonic acid group or its alkali metal salt into the phenyl group at the side chain terminal, a phenyl group, a pyridinyl group or a naphthalenyl group may be introduced at a desired position among five substitution positions of the phenyl group at the side chain terminal group position and number of the sulfonic acid group or the alkali metal salt thereof can be easily controlled by introducing a sulfonic acid group or an alkali metal salt thereof into a phenyl group, a pyridinyl group or a naphthalenyl group by substituting two or more naphthalenyl groups. When a phenyl, pyridinyl or naphthalenyl group is further introduced at a desired position (s) among the five substitution positions of the phenyl group at the side chain terminal, the steric hindrance is reduced during the sulfonation reaction, And the control of the introduction position and number of the alkali metal salt or its alkali metal salt becomes easy.

For example, the present invention can introduce a multi-phenyl pendant, which is a large-sized substituent, into a post-treatment sulphonate, and substitute a sulfonic acid group or an alkali metal salt at the end thereof to densely cluster a plurality of sulfonic acid groups. Accordingly, the polymer of the present invention can induce effective phase separation of a hydrophilic domain and a hydrophobic domain by forming a sulphonated structure in which a sulfonic acid group is densely and locally substituted at the terminal of one phenylene repeating unit.

Further, in order to form a hydrophilic repeating unit having a dense sulfonic acid group by a nucleophilic substitution reaction, a phenyl functional group in which a sulfonated phenyl, a sulfonated pyridinyl or a sulfonated naphthalenyl group, which is sulfonated, A hydrophilic repeating unit having a plurality of sulfonic acid groups in the side chain can be formed without damaging the main chain skeleton.

As described above, instead of directly introducing a sulfonic acid group into the phenyl group located at the end of the side chain, introduction of a polyphenyl pendant as a substituent and sulfonation can increase the fluidity of the hydrophilic part composed of the sulfonic acid group to more effectively form a hydrophilic channel, It can induce phase separation. In addition, the degree of sulfonation may be controlled by adjusting the number of the multiple phenylpendants introduced. On the other hand, since the sulfonic acid group is located far from the polymer backbone framework, the separation membrane prepared from the polymer backbone structure is reduced by reducing the decomposition possibility of the polymer backbone structure.

,

,

(이때, M=수소원자 또는 알칼리금속(Li, Na, K, Rb, Cs 또는 Fr)) 등이 있다.In the present invention, preferred examples of the sulfonated phenyl, sulfonated pyridinyl or sulfonated naphthalenyl substituted with a sulfonic acid group or an alkali metal salt thereof include

,

,

(Where M = a hydrogen atom or an alkali metal (Li, Na, K, Rb, Cs or Fr)).

On the other hand, since the sulfonic acid group and the alkali metal salt thereof are hydrophilic, the water resistance of the polymer electrolyte membrane deteriorates when a sulfonic acid group is introduced in a large amount, and the mechanical strength and the degree of integration of the polymer electrolyte membrane are lowered due to swelling as the water content increases. It may be difficult to satisfy the physical properties of the polymer electrolyte membrane. Accordingly, since the polymer of the present invention contains the hydrophobic monomer represented by the above formula (2) in the skeleton, it can provide an increased mechanical strength and can effectively control the ion exchange rate.

The polymer of the present invention may be symmetrically substituted with a sulfonated phenyl, sulfonated pyridinyl or sulfonated naphthalenyl group substituted with a sulfonic acid group or its alkali metal salt in R ₁ to R ₅ have. For example, the position of the combination selected from the group consisting of (R ₁ and R ₅ ), (R ₂ and R ₄ ), (R ₁ , R ₃ and R ₅ ) and (R ₁ , R ₂ , R ₄ and R ₅ ) May be substituted with a sulfonated phenyl group, a sulfonated pyridinyl group or a sulfonated naphthalenyl group substituted with a sulfonic acid group or an alkali metal salt thereof.

A "halogen" is an atom selected from fluorine (F), chlorine (Cl), bromine (Br) and iodine (I).

"Alkyl" is a saturated linear or branched structure of from 1 to 20 carbon atoms, or a saturated cyclic structure consisting of from 3 to 20 carbon atoms. For example, methyl, ethyl, n-propyl, i-propyl (isopropyl), n-butyl, i-butyl, t-butyl, n-dodecyl, cyclopropyl or cyclohexyl groups do. And may contain one or more heteroatoms selected from oxygen, sulfur and / or nitrogen in the cyclic structure.

"Aryl" means a functional group or substituent derived from an aromatic ring compound. The cyclic compound may be composed of only carbon atoms and may include one or more hetero atoms selected from oxygen, sulfur and / or nitrogen. For example, the carbon-only aryl group includes phenyl, naphthyl, anthracenyl and the like. Examples of the aryl group containing a hetero atom include thienyl, indolyl, Pyridinyl, and the like. The heteroatom-containing aryl may be heteroaryl, but in the present invention, it is aryl.

The terms "perfluoroalkyl", "perfluoroaryl", "-O-perfluoroaryl", and "perfluoroalkylaryl" Means alkyl, aryl and -O-aryl in which each of the hydrogen atoms thereof is replaced by a fluorine atom (F).

The phenylene groups in the polymer backbone according to the present invention may be orthogonal (1,2-phenylene), meta (1,3-phenylene), or para (1,4-phenylene). And may be para-form.

On the other hand, X and Y connected to each other via the benzene ring may be located in ortho, meta or para to each other.

The polymer forming the separation membrane according to the present invention is a polymer having two or more phenylene repeating units The polymer may be a random polymer, an alternating polymer, or a sequential polymer. The polymer may be a block copolymer. When sufficiently limited, the molar ratio of each repeating unit can be varied variously.

The ion conductive polymer forming the separation membrane of the present invention may have a skeleton containing a repeating unit represented by the following Formula 3:

(3)

In Formula 3,

_{A 1, A 2, B,} R 1 to R _5, R ₆ to R _9, R ₁₀ to R _14, a and b are as respectively defined in claim 1, m, n and p are each independently 1 or more.

The fact that the skeleton of the polymer comprises at least one repeating unit represented by the formula (1) and at least one repeating unit represented by the formula (2) contributes to decrease the pKa of the polymer according to the present invention, as compared with the standard polymer according to the prior art. This decrease in pKa is due to the increase in acidity due to the substituted sulfonic acid groups, and thus the modified polymer can be used as a film in battery devices operating at high temperatures.

As shown in Formula 3, a polymer capable of enhancing chemical stability against various radicals can be provided by forming a back bone of a polymer as a carbon-carbon bond without a weak ether bond (-O-). By using such a polymer, it is possible to provide a separation membrane for a redox flow battery which exhibits high ion conductivity and chemical stability at the same time.

In the block copolymer including the phenylpentane substituted with at least two sulfonated aromatic groups forming the electrolyte membrane of the present invention, that is, the block copolymer represented by the general formula (3), m and n are preferably 1: 2 to 1:30, Preferably 1: 5 to 1:15, although the present invention is not limited thereto. For example, the polymer of the present invention can be obtained by polymerizing a polymer in which 1 to 30, preferably 5 to 15, hydrophobic repeating units represented by the general formula (2) are bonded to one hydrophilic repeating unit containing multiple phenylpentene represented by the general formula And may be a polymer formed by repeating units.

Preferably, the ion-conducting polymer comprising a phenyl pendant substituted with two or more sulfonated aromatic groups forming an electrolyte membrane according to the present invention has an Mn (number-average molecular weight) of 10,000 to 1,000,000 or an Mw of 10,000 to 10,000,000 (Molecular weight of weight-average molecular weight). When the molecular weight is low, for example, when it is 10,000 or less, film formation is difficult, the moisture content is increased, and it is easily decomposed by the attack of radical, so that conductivity and durability may be decreased. On the other hand, in the case where the molecular weight is high, for example, 1,000,000 or more, the rapidly increasing viscosity may make the preparation of the polymer solution and molding into a film difficult, making the film production process impossible.

Electrolyte ion conductive polymer represented by general formula (3) to form a film of the present invention is preferably A ₁ is - (C = O) -, - (SO 2) -, -CF 2 - or _{- (C (CF 3) 2} ) -; B is -O-, -S-, - (SO ₂ ) - or - (C = O) -; A ₂ is - (C = O) -; R ₁ to R ₅ are both a sulfonated phenyl group, a sulfonated pyridinyl group or a sulfonated naphthalenyl group substituted with a sulfonic acid group or an alkali metal salt thereof; And R ₆ to R ₁₄ are both hydrogen atoms; a and b are each independently an integer of 1 or more and 10 or less, more preferably A ₁ is - (C = O) -; B is -O-; A ₂ is - (C = O) -; R ₁ to R ₅ are both a sulfonated phenyl group substituted with a sulfonic acid group or an alkali metal salt thereof; And R ₆ to R ₁₄ are both hydrogen atoms; a " and " b "

The separation membrane of the present invention can be produced by any known molding method using a polymer comprising a phenylpentane substituted with two or more sulfonated aromatic groups, which is the ion conductive polymer.

For example, the polymer is dissolved in a solvent such as N-methylpyrrolidone (NMP), dimethylformamide, dimethylsulfoxide or dimethylacetamide, and the solution is poured into a plate such as a glass plate The polymer can be dried to obtain a film of several to several hundreds of μm, preferably 10 to 120 μm, more preferably 50 to 100 μm thick, and then desorbed from the plate. The above-mentioned solvent is only illustrative, and the scope of the present invention is not limited thereto. Conventional organic solvents may be used as long as they dissolve the polymer and can be evaporated under the drying condition. Specifically, the same organic solvent as that used in the preparation of the polymer may be used.

Or by decreasing the rate of dimensional change, the ion conductive polymer may be impregnated into a nanofiber support to prepare a reinforced composite membrane. The "nano web support" is composed of a collection of nanofibers connected three-dimensionally irregularly and discontinuously and thus comprises a number of uniformly distributed pores. And thus includes a plurality of uniformly distributed pores.

Preferably, the nanoweb support can be selected from materials that do not have electrochemical activity. Non-limiting examples of materials constituting the nano web support include polyimide, polymethylpentene, polyester, polyacrylonitrile, polyvinylamide, polyethylene, polypropylene, polyvinyl fluoride, polyvinyl difluoride, nylon, Polybenzoxazole, polyethylene terephthalate, polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone or a combination thereof. That is, the nano web supporter itself has no electrochemical activity, but exhibits the characteristics of the ion exchange membrane through the impregnated ion conductive polymer. As a result, the heat resistance, the chemical resistance, and the mechanical properties can be improved as compared with the separation membrane produced only by the ion conductive polymer.

The ion-conductive polymer may be filled in the nano-web supporter using a supporting or impregnating process, but the present invention is not limited thereto. Various methods known in the art such as a laminating process, a spray process, a screen printing process, and a doctor blade process may be used .

According to a specific embodiment of the present invention, the prepared polymer is dissolved in NMP and poured into a silicon mold having a predetermined size and dried at 60 to 100 ° C, preferably 70 to 90 ° C for 12 to 36 hours, preferably 18 to 30 hours So that a film can be obtained. The polymer was impregnated into a polyimide nano web support to prepare a reinforced composite membrane. The obtained membrane may be washed with a sulfuric acid solution and distilled water in order to convert the membrane prepared in the form of sodium salt into a proton-type polymer membrane.

It is preferable that the isolation film has a thickness of 10 mu m to 1000 mu m. If the thickness of the separator is less than 10 탆, the mechanical strength and shape stability may be deteriorated. If the thickness is more than 1000 탆, the resistance loss may increase.

The redox flow battery according to the present invention is a redox flow battery having a positive electrode, a positive electrode electrolyte, a separator according to the present invention, a negative electrode electrolyte and a negative electrode.

The positive electrode and the negative electrode may be electrode materials conventionally used in the art. For example, carbon felt, carbon nonwoven fabric, graphite felt, graphite plate and the like can be used, but the present invention is not limited thereto.

1, the battery includes a cell housing 51 having a predetermined size, an ion exchange membrane 11 disposed across the center of the cell housing, an ion exchange membrane 11 disposed inside the cell housing, (21) and a cathode (22) electrode located on both sides of the left and right sides separated by the exchange membrane, and an upper electrode and a lower electrode formed on the upper and lower ends of the cell housing on the side where the anode electrode is located, And a cathode electrolyte inlet (31) and a cathode electrolyte outlet (32), which are formed at the upper and lower ends of the cell housing on the side of the cathode electrode, for performing the inflow and outflow of the electrolyte used for the cathode electrode 41 and a cathode electrolyte outlet 42.

Preferably, the redox flow cell according to the present invention comprises a V (IV) / V (V) redox couple as a cathode electrolyte and a pre-vanadium-based redox couple using a V (II) / V Redox battery; A vanadium-based redox battery using a halogen redox couple as a cathode electrolyte and a V (II) / V (III) redox couple as a cathode electrolyte; A polysulfide bromine redox cell using a halogen redox couple as a positive electrode electrolyte and a sulfide redox couple as a negative electrode electrolyte; Or a zinc-bromine (Zn-Br) redox battery using a zinc redox couple as a positive electrode electrolyte and a zinc redox couple as a negative electrode electrolyte.

A separation membrane prepared from an ion conductive polymer containing phenyl pendant substituted with two or more sulfonated aromatic groups according to the present invention can provide excellent ion conductivity, mechanical strength, and chemical stability. In addition, the redox flow battery having such a structure can exhibit excellent cell performance even when it is repeatedly charged / discharged dozens of times and can maintain a high discharge charge retention ratio.

1 is a schematic view showing a configuration of a general redox flow battery.
Figure 2 is a ¹ H NMR spectrum of an ion conductive polymer PBP107 comprising a phenyl pendant substituted with two or more sulfonated aromatic groups according to one embodiment of the present invention.
Figure 3 is a ¹ H NMR spectrum of an ion conducting polymer PBP108 comprising a phenyl pendant substituted with two or more sulfonated aromatic groups in accordance with one embodiment of the present invention.
Figure 4 is a ¹ H NMR spectrum of an ion conducting polymer PBP110 comprising phenyl pendant substituted with two or more sulfonated aromatic groups according to one embodiment of the present invention.
FIG. 5 is a graph illustrating the performance of a single cell having a PBP 107 polymer ion exchange membrane according to an embodiment of the present invention. And the charging capacity according to the number of charging / discharging repetition.
FIG. 6 is a graph illustrating the performance of a single cell having a PBP 107 polymer ion exchange membrane according to an embodiment of the present invention. And the discharge capacity according to the number of charge / discharge repetitions.
7 is a graph showing energy efficiency (EE), coulombic efficiency (CE), and voltage efficiency (voltage) of a single cell having a PBP107 polymer ion exchange membrane according to an embodiment of the present invention. efficiency VE).
8 is a view showing an image of a reinforced composite membrane obtained by repeatedly charging / discharging a single cell having a reinforced composite membrane containing a PBP107 polymer according to an embodiment of the present invention as a separation membrane 20 times.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited to these examples.

Manufacturing example  One: PBP -107 (m = 1, n = 7)

1.1. Fried - Craft Acylation  reaction( Friedel - Craft acylation )

≪ 4 & Fluoro -2,5- Dichlorobenzophenone ( M1 ) Manufacturing>

13.4 g (139 mmol) of fluorobenzene and 9.3 g (69.7 mmol) of anhydrous aluminum chloride were mixed with 20 ml of nitromethane in a round bottom flask and cooled to 0 占 폚. 14.6 g (69.7 mmol) of 2,5-dichlorobenzoyl chloride was slowly added thereto, the temperature was raised to room temperature, and the mixture was stirred for 24 hours while maintaining the temperature. The reaction was mixed with dilute aqueous hydrochloric acid solution and filtered to collect the precipitate. The color was removed with activated charcoal and recrystallized from a n-hexane / ethyl acetate (4: 1) solution. Yield 72.5%.

<2,5- Dichlorobenzophenone ( M2 ) Manufacturing>

To a round bottom flask was added 25 g (119.3 mmol) of 2,5-dichlorobenzoyl chloride and 18.1 g (238.6 mmol) of benzene in 30 ml of nitromethan and cooled to 0 占 폚. After 15.9 g (119.3 mmol) of anhydrous aluminum chloride was added to the mixture, the temperature was raised to room temperature and the mixture was stirred for 24 hours. The reaction was mixed with dilute aqueous hydrochloric acid solution and filtered to collect the precipitate. The color was removed by activated charcoal and recrystallized from n-hexane / ethyl acetate (8: 1) solution. Yield 71.3%.

1.2. Colon coupling reaction ( Colon coupling reaction )On by Sulfonation  The unit copolymer before reaction P1 (m = 1, n = 7)

To the reactor was added 0.324 g (1.484 mmol, 7 mol% of monomer) of triphenylphosphine, 10.388 mmol (50 mol% of monomer) and 5.822 g (89.04 mmol of monomer, 4.2 eq) of nickel bromide , And 13 ml of DMAc (dimethylacetamide) was added thereto, followed by heating to 80 ° C. Stirring was continued for about 30 minutes, and M1 (0.77 g, 2.84 mmol) and M2 (5.0 g, 19.9 mmol) dissolved in 40 ml of DMAc were added. The mixture was stirred while maintaining the temperature for 8 hours, and then the temperature was lowered to room temperature and then mixed with 10% hydrochloric acid / methanol solution to remove zinc. After filtration, the solid obtained by boiling in methanol was obtained by vacuum drying. Yield 87.4%.

1.3. Nucleophilic  Substitution reaction Nucleophilic substitution reaction )On by Multipage Neil Pendant ( 멀티 닐 pendant Introduction - P2 (m = 1, n = 7)

4 g of P1 (m = 1, n = 15) was dissolved in a mixed solvent of 100 ml of DMAc and 30 ml of toluene. K ₂ CO ₃ 0.2 g (1.5 mmol) and hexaphenylbenzene alcohol 1.88 g (3.41 mmol) Lt; 0 &gt; C for 3 hours. The temperature was further raised to 175 DEG C and the toluene was removed using a Dean-Stark trap, followed by further stirring for 24 hours. After the temperature was lowered to room temperature, K ₂ CO ₃ and salts were removed by filtration, and then methanol was added to obtain a precipitate. The precipitate was filtered off with methanol and vacuum dried. Yield 88.7%.

1.4. after Sulfonation  By reaction PBP -107 (m = 1, n = 7)

To a solution of 6.37 g (56 mmol) of chlorosulfonic acid in 150 ml of dichloromethane, 3 g of P2, which was completely dissolved in dichloromethane, was slowly added at room temperature. After stirring for 24 hours, the resulting precipitate was filtered and washed several times with distilled water and hot distilled water. After washing with 0.3 wt% K ₂ CO ₃ aqueous solution for 2 hours, it was washed again with distilled water and vacuum dried. Yield 82.7%.

The synthesized PBP-107 polymer was identified by ¹ H NMR, and the result is shown in FIG.

Manufacturing example  2: PBP -108 (m = 1, n = 8)

2.1. Colon coupling reaction ( Colon coupling reaction )On by Sulfonation  The unit copolymer before reaction P1 (m = 1, n = 8)

Monomers M1 and M2 were prepared by the method described in 1.1 of Preparation Example 1, 1.1. 0.67 g of M1 (2.49 mmol) and 5.0 g of M2 (19.9 mmol) were reacted in the same manner as described in Preparation Example 1.2 to give P1 (m = 1, n = 8). Yield 88.4%.

2.2. Nucleophilic  Substitution reaction Nucleophilic substitution reaction )On by Multiple phenyl  pendant( 멀티 닐 pendant Introduction - P2 (m = 1, n = 8)

4 g of P1 (m = 1, n = 8) obtained in Preparation Example 2.1 was reacted with 1.65 g of hexaphenylbenzene alcohol (2.99 mmol) according to the method described in Preparation Example 1.3 to give P2 (m = 1, n = 8). Yield 86.7%.

2.3. after Sulfonation  By reaction PBP -108 (m = 1, n = 8)

(M = 1) was obtained by reacting 3 g of P2 (m = 1, n = 8) obtained in Preparation Example 2.2 and 5.92 g (52 mmol) of chlorosulfonic acid by the method described in Production Example 1.4. , n = 8). Yield 80.2%.

The synthesized PBP-108 polymer was identified by ¹ H NMR and the results are shown in FIG.

Manufacturing example  3: PBP -110 (m = 1, n = 10)

3.1. Colon coupling reaction ( Colon coupling reaction )On by Sulfonation  The unit copolymer before reaction P1 (m = 1, n = 10)

Monomers M1 and M2 were prepared by the method described in 1.1 of Preparation Example 1, 1.1. 0.54 g of M1 (1.99 mmol) and 5.0 g of M2 (19.9 mmol) were reacted in the same manner as described in Preparation Example 1.2 to give P1 (m = 1, n = 10). Yield 90.7%.

3.2. Nucleophilic  Substitution reaction Nucleophilic substitution reaction )On by Multiple phenyl  pendant( 멀티 닐 pendant Introduction - P2 (m = 1, n = 10) Production

4 g of P1 (m = 1, n = 10) obtained in Preparation Example 3.1 was reacted with 1.32 g of hexaphenylbenzene alcohol (2.34 mmol) according to the method described in Preparation Example 1.3 to give P2 (m = 1, n = 10). Yield 88.9%.

3.3. after Sulfonation  By reaction PBP -110 (m = 1, n = 10)

(M = 1) was obtained by reacting 3 g of P2 (m = 1, n = 10) obtained in Production Example 3.2 and 5.38 g (42 mmol) of chlorosulfonic acid by the method described in Production Example 1.4. , n = 10). Yield 82.7%.

The synthesized PBP-110 polymer was identified by ¹ H NMR and the results are shown in FIG.

Example  1: Preparation of electrolyte membrane

0.5 g of the polymer prepared in Preparative Example 1, 2 or 3 was dissolved in 10 ml of DMSO and the unreacted polymer was removed using a 5 μm syringe filter. The filtered polymer solution was poured into a 8 cm x 8 cm silicon mold provided on a glass plate and dried at 80 ° C for 24 hours. The dried polymer film was further dried in a 160 [deg.] C vacuum oven for 24 hours to completely remove the inner, unremoved solvent. After drying, it was treated with 1.5 M sulfuric acid aqueous solution for 24 hours and immersed in distilled water for at least 24 hours to remove residual acid.

Experimental Example 1: Confirmation of Physical Properties of Electrolyte Membrane

The electrolyte membranes of various compositions were prepared by varying the m and n values by controlling the amounts of the reactants using the reaction of the above preparation examples, and the physical properties were measured. PBP-107 (m = 1, n = 7), PBP-108 (m = 1, n = 8) and PBP-110 (m = 1, n = 10) represented by the general formula ) Was used as a test group, and Nafion 212 represented by the following Chemical Formula 4 of 0.002 inches in thickness was used as a comparative test group to measure conductivity, dimensional change and water uptake.

[Chemical Formula 4]

First, the proton conductivity was measured at 100% relative humidity at 25 ° C and 80 ° C using an AC impedance analyzer (Solatron 1280, Impedance / gain phase analyzer). Four prove conductivity cells were measured in the in-phase direction in the range of 0.1 to 20 kHz. The temperature was maintained for 30 minutes in the thermo-hygrostat chamber before measurement, and the conductivity was calculated by the following equation.

Where I is the distance between the electrodes, R is the impedance of the film, and S is the surface area over which the protons move.

Next, the degree of dimensional change was measured. The volume of the wet film (V _wet ) was measured after immersing the membrane in distilled water for 24 hours to measure the degree of dimensional change, and the wet film was vacuum dried again at 120 ° C for 24 hours to measure the volume (V _dry ). These measured values were substituted into the following equations to calculate the degree of dimensional change.

Finally, water uptake (WU) was measured. The water absorption rate was calculated by measuring the mass of the wet film (W _wet ) and the mass of the dried film (W _dry ) using the following equation.

The molecular weight was measured by measuring intrinsic viscosity. In order to measure the intrinsic viscosity, the prepared polymer was dissolved in NMP and the viscosity of the solution prepared at a concentration of 0.5 g / dl was measured in a 25 ° C. thermostat using a Ube load viscometer.

The results thus obtained are summarized in Table 1 below.

Example  1: Two or more Sulfonation Aromatic group  Substituted Phenyl  Having a polymer membrane made of a block copolymer containing a pendant Redox Flow  Battery configuration and performance evaluation

An ion exchange membrane containing the polymers (PBP-107, PBP-108 and PBP-110) prepared according to the above Preparation Example was prepared and membranes having thicknesses of 30 μm and 80 μm were prepared with different thicknesses, respectively. The membrane containing PBP-107 polymer was cut into 70 mm × 50 mm and mounted on a single cell (11) as shown in Fig. 1 to measure the charge / discharge test and efficiency of the cell. 5 to 7.

Specifically, the single cell was made of carbon felt having a thickness of 5 mm, which was treated with an anode and a cathode material by heat and acid, respectively. The electrode frame material was acrylic and the end plate material was Hexion bakelite. V (IV) / V (V) redox couple was used as the anode electrolyte and V (II) / V (III) redox couple was used as the cathode electrolyte.

In order to improve the dimensional stability of the ion exchange membrane, a single cell (PBP-107 + NanoWeb) with a reinforced composite membrane prepared by impregnating PBN-107 on a polyimide (PI) Respectively. As a comparative example, a single cell (Nafion 212) in which Nafion, which is widely used as an ion conductor in a conventional redox flow cell, was introduced as an ion exchange membrane was prepared by the same method. (30 mu m) and PBP-107 (80 mu m) and a Nafion ion exchange membrane (Nafion 212) prepared from the above PBP-107 polymer and having a thickness of 30 mu m or 80 mu m The results are shown in Table 2. The performance of each single cell was summarized by numerical values.

The driving test for evaluating the performance of the single cell was performed at room temperature, i.e., at 25 캜. The flow rate of the electrolyte was fixed at 40 ml / min. The charge proceeded to 1.6 V with a current density of 50 mA / cm ² and the discharge proceeded to 1.0 V with the same current density. All single cells were charged / discharged 20 times in order to test the durability.

As shown in FIGS. 5 to 7, a single cell having a PBP-107 ion exchange membrane exhibited excellent cell performance even after repeated charge / discharge cycles, exhibited a constant charge / discharge capacity, The PBP-107 ion exchange membrane of the present invention has a high charge / discharge capacity. Also, the energy efficiency (EE), the coulombic efficiency (CE), and the voltage efficiency (VE) were kept high regardless of the thickness of the ion exchange membrane, .

When cell performance and discharge charge retention ratio were compared with a single cell having an ion exchange membrane containing PBP-107 and a Nafion 212 ion exchange membrane, as shown in Table 2, a single cell with an ion exchange membrane containing PBP-107 Cell exhibited a higher discharge charge retention ratio in the case of continuous charging / discharging although the discharging charge amount was somewhat lower than that of the single cell having the conventionally commercialized Nafion 212 ion exchange membrane. In addition, Nafion has excellent characteristics in terms of energy efficiency, electricity quantity efficiency and voltage efficiency. Therefore, PBP-107 is an excellent ion conductor exhibiting a discharge charge retention ratio, energy efficiency, electricity quantity efficiency and voltage efficiency equal to or higher than those of a cell equipped with an ion exchange membrane and having Nafion. On the other hand, it was confirmed that the PBP-107 exhibited a higher discharge charge than that of the ion exchange membrane prepared to a thickness of 30 μm, The performance of the ion exchange membrane can be further improved.

FIG. 8 shows an image of a PBP-107 ion exchange membrane separated from a cell in which charging / discharging was repeated 20 times. As shown in FIG. 8, it was confirmed that the PBP-107 ion exchange membrane was an ion exchange membrane having excellent mechanical strength, which was not damaged even by repeated charge / discharge more than 20 times. In general, an ion exchange membrane prepared from an ion conductive polymer containing phenylpentane substituted with two or more sulfonated aromatic groups including PBP-107 according to the present invention is not only an excellent ion conductor but also has excellent mechanical strength, It can be used as a separation membrane of redox flow battery.

11: Separation membrane (ion exchange membrane)
21: anode
22: cathode
31: anode electrolyte inlet
32: anode electrolyte outlet
41: cathode electrolyte inlet
42: cathode electrolyte outlet
51: cell housing

Claims (18)

1. A separator for a redox flow cell produced from an ion conductive polymer having a backbone comprising at least one phenylene repeating unit represented by the following formula (1) and at least one phenylene repeating unit represented by the following formula (2), wherein the ion conductive polymer Having a number-average molecular weight (M _n ) of from 1 to 1,000,000 or a weight-average molecular weight (M _w ) of from 10,000 to 10,000,000.
[Chemical Formula 1]

(2)

In the above Formulas 1 and 2,
A ₁ and A ₂ is a single bond, each independently, - (C = O) - , - (P = O) -, - (SO 2) -, -CF 2 - or _{- (C (CF 3) 2} ) - ego;
B is -O-, -S-, - (SO ₂ ) -, - (C = O) -, -NH- or -NR ₁₅ -, wherein R ₁₅ is a C 1 to C 6 alkyl group;
At least two or all of R ₁ to R ₅ are a sulfonated phenyl, a sulfonated pyridinyl or a sulfonated naphthalenyl which is substituted with a sulfonic acid group or an alkali metal salt thereof, and R ₁ To R ₅ each independently represent a hydrogen atom (-H), a halogen atom (-X), a sulfonic acid group (-SO ₃ H), a phosphoric acid group (-PO ₃ H ₂ ), an acetic acid group (-CO ₂ H) (-NO ₂ ), a perfluoroalkyl group, a perfluoroalkylaryl group optionally containing one or more oxygen, nitrogen or sulfur atoms in its chain, a perfluoroaryl group and an -O-perfluoroaryl group, or one Or an aryl group substituted with at least one halogen, a sulfonic acid group, a phosphoric acid group, an acetic acid group or a nitro group, and the perfluoro group may include a substituent selected from the group consisting of sulfonic acid, phosphoric acid, acetic acid and nitro, , The phosphoric acid group and the acetic acid group are alkaline May be in the form of a metal salt;
Each of R ₆ to R ₉ may independently include a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a sulfonic acid group, a phosphoric acid group, an acetic acid group and a nitro group, and the sulfonic acid group, phosphoric acid group and acetic acid group may be in the form of an alkali metal salt ;
R ₁₀ to R ₁₄ each independently may contain a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a sulfonic acid group, a phosphoric acid group, an acetic acid group and a nitro group, and the sulfonic acid group, phosphoric acid group and acetic acid group may be in the form of an alkali metal salt Each of which is independently a hydrogen atom, at least one fluorine atom (F) (except when all are fluorine), an aryl group, a perfluoroalkyl group, optionally at least one oxygen, nitrogen and / A perfluoroalkylaryl group including a sulfur atom, a perfluoroaryl group and an -O-perfluoroaryl group;
a and b are each independently an integer of 1 or more and 10 or less.
The method according to claim 1,
Wherein the positions substituted with a sulfonated phenyl, sulfonated pyridinyl or sulfonated naphthalenyl group substituted with a sulfonic acid group or an alkali metal salt thereof in R ₁ to R ₅ are symmetrical.
The method according to claim 1,
The position of the combination selected from the group consisting of (R ₁ and R ₅ ), (R ₂ and R ₄ ), (R ₁ , R ₃ and R ₅ ) and (R ₁ , R ₂ , R ₄ and R ₅ ) A sulfonated phenyl, a sulfonated pyridinyl, or a sulfonated naphthalenyl substituted with an alkali metal salt thereof.
The method according to claim 1,
Wherein the phenylene groups of the skeleton are connected to each other at para positions.
The method according to claim 1,
Wherein the polymer is a random, alternating, block, or sequential polymer.
delete The method according to claim 1,
And a skeleton containing a repeating unit represented by the following formula (3):
(3)

In Formula 3,
_{A 1, A 2, B,} R 1 to R _5, R ₆ to R _9, R ₁₀ to R _14, a and b are as respectively defined in claim 1, m, n and p are each independently 1 or more.
8. The method of claim 7,
Wherein the ratio of m to n in Formula 3 is 1: 1 to 1:30.
The method according to claim 1,
A ₁ is - (C = O) -, - (SO ₂ ) -, -CF ₂ - or - (C (CF ₃ ) ₂ ) -;
B is -O-, -S-, - (SO ₂ ) - or - (C = O) -;
A ₂ is - (C = O) -;
R ₁ to R ₅ are both a sulfonated phenyl group, a sulfonated pyridinyl group or a sulfonated naphthalenyl group substituted with a sulfonic acid group or an alkali metal salt thereof; And
R ₆ to R ₁₄ are both hydrogen atoms;
and each of a and b is independently an integer of 1 or more and 10 or less.
10. The method of claim 9,
A ₁ is - (C = O) -;
B is -O-;
A ₂ is - (C = O) -;
R ₁ to R ₅ are both a sulfonated phenyl group substituted with a sulfonic acid group or an alkali metal salt thereof; And
R ₆ to R ₁₄ are both hydrogen atoms;
and a and b are 1, respectively.
The method according to claim 1,
Wherein the separation membrane is a composite membrane formed by impregnating a nanoparticle support with a polymer membrane or an ion conductive polymer forming the ion conductive polymer itself.
12. The method of claim 11,
Wherein the nano web support is selected from the group consisting of polyimide, polymethylpentene, polyester, polyacrylonitrile, polyvinylamide, polyethylene, polypropylene, polyvinyl fluoride, polyvinyl difluoride, nylon, polybenzoxazole, polyethylene terephthalate , Polytetrafluoroethylene, polyarylene ether sulfone, polyether ether ketone, and combinations thereof.
A redox flow battery having a separator, a negative electrode electrolyte and a negative electrode according to any one of claims 1 to 5, and 12 to 12, a positive electrode, a positive electrode electrolyte.
14. The method of claim 13,
The battery includes a cell housing 51 having a predetermined size,
An ion exchange membrane 11 disposed across the center of the cell housing,
An anode (21) and a cathode (22) electrode located on both left and right sides separated by the ion exchange membrane inside the cell housing,
A positive electrode electrolyte inlet 31 and a positive electrode electrolyte outlet 32 formed at the upper and lower ends of the cell housing on the side where the positive electrode is located to perform the inflow and outflow of the electrolyte used for the positive electrode,
And a negative electrode electrolyte inlet (41) and a negative electrode electrolyte outlet (42) formed at the upper and lower ends of the cell housing on the side where the negative electrode is located to perform the inflow and outflow of the electrolyte used for the negative electrode.
14. The method of claim 13,
Wherein the cathode is a pre-vanadium-based redox battery using a V (IV) / V (V) redox couple as the positive electrode electrolyte and a V (II) / V (III) redox couple as a negative electrode electrolyte. battery.
14. The method of claim 13,
Wherein the cathode is a vanadium-based redox battery in which a halogen redox couple is used as the positive electrode electrolyte and a redox couple of V (II) / V (III) is used as a negative electrode electrolyte.
14. The method of claim 13,
Characterized in that the battery is a polysulfide bromine redox battery using a halogen redox couple as the positive electrode electrolyte and a sulfide redox couple as the negative electrode electrolyte.
14. The method of claim 13,
Wherein the battery is a zinc-bromine (Zn-Br) redox battery using a halogen redox couple as the positive electrode electrolyte and a zinc redox couple as a negative electrode electrolyte.

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