KR20170070066A - A method for reducing membrane permeability to vanadium ions and a vanadium redox battery comprising the membrane produced by the method - Google Patents

Abstract

The present invention relates to a method for reducing the permeability of a cation exchange membrane to vanadium ions. The present invention also relates to a vanadium redox battery comprising a membrane modified by the method to provide low permeability to vanadium ions for use in a vanadium redox battery.

Description

A method for reducing membrane permeability to vanadium ions and a vanadium redox battery comprising the membrane produced by the method

This application claims the benefit of the filing date of Russian Patent Application No. 2014142533 filed with the Russian Patent Office on October 21, 2014, the entire contents of which are incorporated herein by reference.

The present invention relates to a method for reducing the permeability of a cation exchange membrane to vanadium ions. The present invention also relates to a vanadium redox battery comprising a membrane modified by the method to provide low permeability to vanadium ions for use in a vanadium redox battery.

As industrial development requires more and more energy, the world reserves of non-regenerative energy sources are rapidly and steadily depleting, which means that the search for new energy sources and the development of methods for industrial use of them will be carried out in modern science and industry Making it one of the top priorities of The lack of a robust energy battery is a major challenge for large-scale enforcement of sustainable energy, solar and wind, as an alternative renewable energy source. The lack of energy-efficient batteries that can be charged quickly is also a major constraint that hinders the large-scale manufacture and use of electric vehicles.

Recently vanadium redox batteries are considered as one of the most promising types of novel batteries due to the specific combination of energy efficiency, capital cost, life cycle cost and absence of specific requirements [G. Kean, AA Shah, FC Walsh. Int. J. Energy Res., 2011, DOI: 10.1002 / er.1863 ]. In redox batteries, two redox couples are used as electroactive materials for energy storage by oxidation and reduction reactions. As described in some publications [A. Rarasuraman, TM Lim, C. Menictas, M. SKyllas-Kazacos. Review of material research and development for vanadium redox flow battery applications. Electrochimica Acta, 101 (2013) 27-40; U.S. Pat. U.S. Patent No. 696452; 704534, US Patent Nos. 6143443 and 6562514], the working principle of a vanadium redox battery is based on the ability of vanadium to exist in four degrees of oxidation V (II), V (III), V (IV) and V (V). A typical battery includes a tank having a cathode electrolyte containing a VO ₂ ⁺ / VO ²⁺ pair and a tank having an anode electrolyte containing a V (II) / V (III) pair. The electrolyte from the tanks circulates through the stack of electrochemical cells connected in series or in parallel by a pump to perform a reaction with the inert electrodes. Each electrochemical cell comprises a negative half cell containing a ₂ ⁺ VO and VO ²⁺ ion positive half-cell and V (III) and V (II) ion-containing. The two half cells are isolated by an ion exchange membrane (IEM), which allows the vanadium ions with different oxidation states to migrate through the membrane, which can lead to loss of battery operating capacity upon mixing Prevent is the main component of the battery. Thus, in addition to low permeability to vanadium ions, ideal membranes must have high hydrogen conductivity, good chemical stability in acidic solutions, high stability to oxidant V (V) and reducing agent V (II), and high mechanical strength.

Since a perfluorinated membrane made from a sulfo-containing copolymer such as Nafion (R) having different amounts of sulfo moieties made in DuPont has a high hydrogen conductivity, excellent durability against an electrolyte solution and a sufficiently high mechanical strength, Most of them are satisfied. A major disadvantage of such a membrane is its high vanadium ion permeability, which is the reason for the self-discharge rate of the battery resulting in a reduction in the effectiveness of the battery.

Many attempts have been reported to reduce the membrane permeability to vanadium ions and improve the operating parameters of the film.

One such attempt is the use of membranes made of alternative polymeric materials and the development of "sandwich" type composite membranes. Polysulfone and its derivatives can be used in conjunction with alternative polymers and copolymers (e.g., EP patent 0790658), mixtures of two or more polymers (e.g., US patent application 2011/0136016), copolymers (e.g., US patent application No. 2011/0318644 and No. 2012/0196188, X. Luo et al. , J. Phys. Chem. B, 2005, 109, 20310-20314), tungstophosphoric acid (tungstophosphoric acid) polypropylene / sulfonate polyetheretherketone [C treated with Jia et al., J. Power Sources, 2010, 195, 4380-4383 ]. However, a common disadvantage of all of the above-mentioned methods is that the reduction of the membrane permeability to vanadium ions is insufficient (approximately 2-10 times) compared to the Nafion membrane.

Many attempts have been made to modify the Nafion membrane to reduce the permeability of the vanadium ion, such as by applying an isophthaloyl dichloride coating to the surface of the Nafion polyanion or polycation through interfacial polymerization on the surface of the Nafion membrane To convert the sulfo groups incorporated in the complex of polyethylenimine adsorbed on the Nafion surface to chloro-sulfo groups [QTLuo, HM Zhang, J. Chen, P. Qian, YF Zhai , J. Membr. Sci., 2008, 311, 98 ], to obtain a polycationic barrier by chemical polymerization of pyrrole and aniline on the membrane surface [B. Schwenzer, S. Kim, M. Vijayakumar, ZG Yang, J. Liu, J. Membr. Sci., 2011, 3 372, 11 ; J. Zeng, C. Jiang, Y. Wang, J. Chen, S. Zhu, B. Zhao, R. Wang, Electrochem. Commun., 2008, 10, 372 ], blocking the surface with an inorganic material such as tetraethoxysilane through a sol-gel reaction performed in situ [J. Xi, Z. Wu, X. Qiu, L. Chen, J. Power Sources, 2007, 166, 531 ; D. Schulte, J. Drillkens, B. Schulte, DU Sauer, J. Electrochem. Soc., 2010,157, A989 ; X. Teng, Y. Zhao, J. Xi, Z. Wu, X. Qiu, L. Chen, J. Membr. Sci., 2009, 341, 149 ; N. Wang, S. Peng, D. Lu, S. Liu, Y. Liu, K. Huang, J Solid State Electrochem., 2011, 1 ], or compounding with polyvinylidene fluoride [Z. Mai, H. Zhang, X. Li, S. Xiao, J. Power Sources, 2011, 196, 5737 ]. Attempts to modify the Nafion membranes described above provide a reduction in permeability to vanadium ions and as a result result in reduced self-discharge rates and increased coulombic efficiency and energy efficiency compared to native Nafion membranes. However, the above-described attempts can reduce the membrane permeability of vanadium ions by up to 10 times. [B. Schwenzer, S. Kim, M. Vijayakumar, ZG Yang, J. Liu, J. Membr. Sci., 2011, 372, 11 ] showed that the aniline polymerization on the surface of the Nafion membrane reduced the permeability of vanadium ion by about two orders of magnitude or more, but using more available analytical methods, But did not provide.

The closest approach to the present invention is described by LANeves, J. Benavente, IMCoelhoso, JGCrespo. J. Membr. Sci., 2010, 347, 42 and LANeves, IMCoelhoso, JGCrespo. J. Membr. Sci., 2010, 360, 363 ), which describe the introduction of large amounts of cationic surfactants into the Nafion membranes for fuel cells as ionic liquid cationic forms. The main purpose of this document was to reduce the moisture permeability occurring in the Nafion membrane at high temperatures, which adversely affects membrane performance in fuel cells. The cationic surfactant was added to the membrane by incubating the membrane in a 40% (w / w) aqueous solution of the surfactant. The cationic surfactant was actually embedded in the Nafion membrane and reached a maximum level of incorporation of the surfactant in the membrane (up to about 90% of the Nafion sulfonate group bound to the surfactant), and was constant after about 20 hours of incubation , Indicating that this resulted in a significant reduction in membrane permeability to methanol and gas. The water loss at the high temperature of the modified membrane was considerably reduced. However, this document does not aim to reduce the membrane permeability of vanadium ions, and this study does not include evidence that the modification of the membrane by the cationic interfacial agent affects the permeability of the vanadium ion.

Another group of researchers, Wu Xue-Wen, LIU Su-Qin, HUANG Ke-Long. Characteristics of CTAB as Electrolyte Additive for Vanadium Redox Flow Battery. Journal of Inorganic Materials Vol. 2010, 25 No. 6. 641-646 describes the use of a cationic surfactant, cetyltrimethylammonium bromide, as an electrolyte additive designed for vanadium redox batteries. The introduction of a surfactant into the electrolyte composition increases the concentration of the electrolyte by increasing the solubility of the V (V) ion, promotes the oxidation / reduction reaction V (IV) / V (V) It has been shown that it has a positive effect on battery performance because it reduces transport resistance. However, the decrease in the membrane permeability to vanadium ions was not the object of the above study, and the above-mentioned modification with the cationic surfactant did not provide any evidence that the membrane permeability to the vanadium ion is effective.

Thus, there is a great need in recent years for the development of simple and feasible methods for significantly reducing the permeability of cation exchange membranes to vanadium ions, especially for Nafion, to use membranes modified from vanadium redox batteries.

The present invention relates to a method for reducing the permeability of a cation exchange membrane to vanadium ions. The present invention also provides a vanadium redox battery comprising a membrane modified by the method to provide low permeability to vanadium ions for use in a vanadium redox battery.

One embodiment of the present invention provides a method of reducing the permeability of a film to vanadium ions. Specifically, the method comprises introducing the cationic surfactant into at least a portion of the membrane surface and the membrane by incubating the membrane in an aqueous or saline solution containing a cationic surfactant or a mixture of the cationic surfactants. According to one example, the membrane is a cation exchange membrane. According to another example, the membrane is a polymer membrane having a sulfo group.

According to the present invention, the reduction in permeability to vanadium ions is achieved by introducing a cationic surfactant (cS) into the membrane by incubating the membrane in an aqueous solution or a saline solution containing a mixture of cationic surfactant or cationic surfactant . The term "introduction of a surfactant into the membrane" means that the cationic surfactant (cS) can be located on the surface of the membrane and / or inside the membrane, preferably both on and within the membrane .

The method according to the above embodiment of the present invention reduces membrane permeability to vanadium ions and is 5 times, more preferably about 10 times greater than the original unmodified membrane permeability in measuring the permeability of vanadyl ion VO ²⁺ , More preferably about 100 times, even more preferably about 1,000 times, still more preferably about 10,000 times, still more preferably about 100,000 times or more.

Another embodiment of the present invention provides a vanadium redox battery comprising an anode, a cathode, and a separator provided between the anode and the cathode, wherein the separator is a film produced by the method described above.

Another embodiment of the present invention is directed to a fuel cell comprising an anode, a cathode and a separator provided between the anode and the cathode, wherein the separator comprises a mixture of a cationic surfactant or a cationic surfactant on the surface of the membrane, Which is a film provided in the vanadium lanthanum battery. Such a film can be produced by the above-described method.

Has a low permeability to the film of vanadium ions according to the embodiment of the present invention, varnishes dill ion permeability measurements when the ^{VO 2+, 6x10 -7 cm 2 min} -1 or less, 5x10 ^-7 cm ² min ^-1 or less, more preferably from 1x10 ^-7 cm ² min ^-1 or less, still more preferably from 1x10 ^-8 cm ² min ^-1 or less, still more preferably from 1x10 ^-9 cm ² min ^-1 or less, still more preferably from 1x10 ^-10 cm ² min ^-1 or less.

Vanadium redox flow batteries comprising modified membranes according to the present invention have the advantage that they have low permeability to vanadium ions and therefore do not destroy the binding between the membrane and the surfactant at high concentrations of the salt.

Best Mode for Carrying Out the Invention

A method according to one embodiment of the present invention is a method for reducing the permeability of a film to vanadium ions.

Specifically, the method comprises introducing the cationic surfactant into at least a portion of the membrane surface and the membrane by incubating the membrane in an aqueous or saline solution containing a cationic surfactant or a mixture of the cationic surfactants.

In the present invention, the term " incubation "means exposing the membrane to a solution. Exposure includes contact.

According to one embodiment, the membrane is a cation exchange membrane. And is not particularly limited as long as it is a membrane used as a cation exchange membrane. For example, the cation exchange membrane to the anionic groups such as sulfo _{(-SO 3 H), -SO 3} - M +, -COOH, -COO - M +, -PO 3 H 2, -PO 3 H - M ⁺ And -PO ₃ ^2- 2M ⁺ can be used, wherein M is a monovalent cation such as Li, Na or K cation.

According to another embodiment, the membrane is a polymer membrane having a sulfo group.

According to this embodiment, when the sulfo group-containing cation exchange polymer membrane is incubated in an aqueous solution or a saline solution containing a cationic surfactant (cS) or a mixture of the cationic surfactants, the cationic surfactant (cS) is introduced to achieve a reduction in the permeability to vanadium ions.

According to another embodiment, the cationic surfactant has a hydrophobic moiety and the membrane comprises a hydrophobic fragment. The hydrophobic moiety of the cationic surfactant and the hydrophobic segment of the membrane may have hydrophobic interactions. For example, the hydrophobic moiety of the cationic surfactant is an alkyl moiety.

Experimental studies performed by the present inventors (more specifically Examples 4 and 5) show that by exposing sulfo containing membranes, such as Nafion-117, to a solution of a cationic surfactant, most of the surfactant (Approximately the surfactant 1 ion per 1 sulphur group of the membrane) indicates that no significant leaching of the cationic surfactant (cS) occurs from the membrane even after long-term incubation of the membrane in distilled water or heating in water and / or sulfuric acid . Thus, the primary action force for the cationic surfactant to bind to the membrane is the electrostatic interaction between the group of cationic surfactants and the sulfoder group of the membrane, while the interaction between the alkyl moiety of the surfactant and the hydrophobic fragment of the membrane The hydrophobic interaction could be assumed to provide additional stabilization of the final structure.

According to the present invention, as the polymer film having the sulfo group, a sulfonic group-containing polymer film prepared by an industrial or experimental method for film formation can be used, and as a non-limiting example, a tetrafluoro Copolymers of ethylene, such as Nafion (R), may be used. Specifically, Nafion membranes include Nafion 112, Nafion 115, Nafion 117, Nafion 125, Nafion 212, Nafion NR211, Nafion NR212, Nafion 1110, and Nafion XL.

The membrane may comprise two or more materials, examples of which include one or more polymers comprising a sulfo group, and / or one or more polymers comprising a carboxyl group, and / or a phosphor-group, , And further one or more non-ionic polymers, and the like.

According to one embodiment, the membrane may be heated successively in a hydrogen peroxide solution, in a sulfuric acid solution and in distilled water, prior to modification with a cationic surfactant.

According to one embodiment, the membrane may be subjected to subsequent boiling in a hydrogen peroxide solution, in a sulfuric acid solution and in distilled water, after modification with a cationic surfactant.

According to one embodiment, the membrane can be successively boiled in a hydrogen peroxide solution, in a sulfuric acid solution and in distilled water, before and after the modification with a cationic surfactant, respectively.

According to one embodiment, the cationic surfactant comprises a compound represented by the following formula (1) or (2) or a mixture thereof.

[Chemical Formula 1]

(2)

In the above formulas (1) and (2)

R < ₁ > is hydrogen, methyl or ethyl,

R ₂ is hydrogen, methyl, ethyl, phenyl, phenylmethyl, hydroxymethyl or hydroxyethyl,

R ₃ is selected from the group consisting of hydrogen, C ₁ to C ₂₀ alkyl, C ₆ to C ₂₀ aryl, C ₇ to C ₂₀ arylalkyl, C ₁ to C ₂₀ hydroxyalkyl, (CH ₂ CH ₂ O) _n R, Or (CH ₂ ) _p COO ^- , wherein n is an integer from 4 to 100, R is hydrogen or C ₁ to C ₂₀ alkyl, p is an integer from 1 to 12,

R ₄ is C ₈ to hydroxyalkyl, -COOR a C ₂₀ alkyl, C ₈ to C ₂₀ of - ", wherein R '', R" COOR "'or-R" OCOR "and R"' is C ₈ To C ₂₀ alkyl, and R "is C ₁ to C ₃ alkylene;

R ₅ is C ₈ to alkyl, -COOR of C ₂₀ - ", wherein R '', R" COOR "'or-R" OCOR "and R" a "is alkyl of from C ₈ to C _20, R" is C ₁ to C ₃ alkylene;

X is an anion group.

According to one example, R ₁ is H, -CH ₃ , or -C ₂ H ₅ .

According to one example, R ₂ is H, -CH ₃ , -C ₂ H ₅ , -C ₆ H ₅ , -CH ₂ C ₆ H ₅ , -CH ₂ OH, or -C ₂ H ₄ OH.

In one example, R ₃ is _{H, -CH 3, -C 2 H} 5, -C 6 H 5, -CH 2 C 6 H 5, -CH 2 OH, -C 2 H 4 OH, (CH 2 CH ₂ O) _n R wherein n is an integer from 4 to 100, R is hydrogen or C ₁ -C ₂₀ alkyl, C ₈ -C ₁₈ alkyl.

In one example, R ₄ is C ₈ -C ₂₀ alkyl, (CH _{2) m} OH (wherein m is an integer from 8 to 20) or _{- (CH 2) k OC (} O) (CH 2) l ( where k Is an integer of 1 to 3, and 1 is an integer of 8 to 18).

According to one example, R ₅ is C ₈ -C ₂₀ alkyl, or - (CH ₂ ) _k OC (O) (CH ₂ ) _l wherein k is an integer from 1 to 3 and 1 is an integer from 8 to 18. .

In one example, X is _{^{-Cl -, -Br -, -CH 3}} OSO 3 -, or -C ₂ H ₅ OSO ₃ ^- a.

According to one embodiment, the cationic surfactant comprises a surfactant having a double tail, examples of which include didecyldimethylammonium bromide, dioctadecyldimethylammonium bromide, and the like.

According to one embodiment, the cationic surfactant includes betaine, such as GENAGEN CAB (alkylamidopropyl betaines) and GENAGEN LAB (alkyldimethyl betaines), which have C ₈ -C ₁₈ alkyl , GLOBALAMINES.

According to one embodiment, the cationic surfactant has a hydroxy group in its side chain, for example Praepagen HY.

According to one embodiment, the introduction of the cationic surfactant into the membrane can be carried out by holding the membrane in an aqueous or saline solution containing a cationic surfactant or a mixture thereof at a temperature of from about 100 ^° C to about 10 ^° C . Reducing the temperature can reduce the rate of adsorption of the cationic surfactant in the membrane and reduce the solubility of the cationic surfactant, thus increasing the time required for membrane incubation in solution.

According to an exemplary embodiment, a solution concentration of the cationic surface active agent is from about 10 ^-5 M to about 1 M, preferably from 10 ^-3 M to 0.5 M, more preferably from 10 ^-2 M to about 0.1 M. Lowering the surfactant concentration to less than 5 ^-10 mM may need to increase the incubation time of the membrane in solution.

The absolute amount of cationic surfactant in solution is determined by the degree of filling D of the desired membrane:

D = [cS] _bound / [SO ₃ H] _membrane (1)

Where [cS] _bound is the amount of cationic surfactant (mole number) _bound to the membrane, and [SO ₃ H] _mem is the absolute amount of sulfo moiety in the membrane (mole number).

[SO ₃ H] _membrane = (m - m H _{2 O} ) / 1100

Where m is the mass of the swollen membrane (grams, g), m _H2O is the mass of water in the sample calculated from the degree of swelling of the membrane determined experimentally, and 1100 is the gram equivalent of the Nafion 117 used in the Examples, Lt; RTI ID = 0.0 > Nafion < / RTI > per sulfated group. If another polymer is used as the material of the membrane, 1100 can be replaced by the dry weight per sulfo group of the polymer.

The absolute amount of the cationic surfactant in the solution required to achieve the desired degree of filling D is determined by the relationship (1) assuming that the surfactant binds quantitatively, so [cS] _bound is the concentration of the cationic surfactant in solution It is equivalent to the total amount. If it is desired to obtain the maximum degree of filling of the membrane, the surfactant in the solution may be present in excess.

The retention time of the membrane in the mixture of the cationic surfactant or the cationic surfactant can be determined by the concentration of the cationic surfactant, the chemical nature of the cationic surfactant and the membrane, and the processing temperature. In general, the membrane incubation time in the surfactant solution varies from about 1 hour to several weeks, more preferably from 10 hours to 48 hours.

According to one embodiment, the cationic surfactant solution may further comprise at least one of inorganic and / or organic salts and alkali metal ions.

The inorganic and / or organic salt may be a water-soluble low-molecular-weight substance such as chloride, bromide, sulfate, phosphate, carbonate, acetate, oxalate and the like. Examples of the metal counter ion include sodium, potassium, lithium, cesium, calcium, magnesium, lanthanum, copper, and nickel ions. The fact that the modified membrane retains extremely low permeability to vanadium ions when left in contact with high salt and acid concentrations (eg, 1 M MgSO ₄ , 1 M VOSO ₄ , 2.5 MH ₂ SO ₄ ) (at least 3 weeks) Indicates that such a high concentration of salt does not destroy the bond between the membrane and the surfactant and, consequently, does not interfere with the bond.

According to one embodiment, the cationic surfactant solution may further comprise an inorganic or organic acid. Examples of the inorganic or organic acid include hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and citric acid.

The method according to the present invention is characterized in that the permeability of the membrane to the vanadium ion is 5 times, more preferably about 10 times, more preferably about 100 times, even more preferably about 1,000 times Preferably about 10,000 times, and even more preferably about 100,000 times or more.

The film obtained by the introduction of the cationic surfactant by the method according to the present invention has a low permeability to vanadium ion and a permeability of 6 x 10 ^-7 cm ² min ^-1 or less when measuring the permeability of the vanadyl ion VO ²⁺ , 1 x 10 ^-7 cm ² min ^-1 or less, still more preferably ¹ x 10 ^-9 cm ² min ^-1 or less, still more preferably ¹ x ^{10 -10} cm ² min ^-1 or less.

According to an embodiment, there is provided a vanadium redox battery comprising an anode, a cathode, and a separator provided between the anode and the cathode, wherein the separator is a film produced by the method described above.

According to one embodiment, there is provided a fuel cell comprising an anode, a cathode and a separator provided between the anode and the cathode, wherein the separator is a membrane in which a mixture of the cationic surfactant or the cationic surfactant is provided on at least a part of the surface of the membrane, ≪ / RTI >

Determination of membrane vanadium permeability to ions

The membrane permeability for vanadium ions is characterized by the permeability of the vanadyl ion V (IV), using a cell consisting of two identical half cells separated by the studied membrane. A 1 M VOSO ₄ aqueous solution in 2.5 M sulfuric acid was placed in one half cell through a specific opening and a 1 M MgSO ₄ solution in 2.5 MH ₂ SO ₄ was added to another half cell. The volume of each solution was 0.8 ml, and the operating area of the membrane in contact with the VOSO ₄ / MgSO ₄ solution was 0.875 cm ² . The filled cell was left at room temperature without agitation. To determine the permeability of the initial (unmodified) membrane, take a 10-200 mkl aliquot from the half-cell containing MgSO ₄ after 30-60 minutes after filling to further measure the vanadium ion concentration through the membrane Respectively. To determine the permeability of the modified membrane, a solution was taken from the half-cell containing MgSO ₄ at 4-30 days after filling.

The vanadium ion concentration was measured as follows using the color reaction with 4- (2-pyridylazo) resorcinol (PAR). To a 10 ml volumetric flask was added 1 ml of 1 M Na-acetate buffer (pH 6.5), 0.5 ml of 0.1% PAR solution, approximately the same volume for neutralizing the sample solution and 2.5 M sulfuric acid to adjust the pH to 6.2 - 6.7 Of 5M NaOH. The solution volume was adjusted to the required value (10 ml) with distilled water (twice distilled). The volume of the test solution was selected such that the final vanadium concentration in the volumetric flask containing PAR was in the range of about 4 x 10 ^-6 to 2 x 10 ^-5 M. The solution was mixed thoroughly and the absorption spectra were recorded in the 450-600 nm range and the optical density was measured at a wavelength of 540 +/- 2 nm corresponding to the maximum absorbance of the complex PAR-V (IV) at pH 6.2 to 6.7.

As a control, and is, all reagents (acetate buffer, PAR and NaOH), except in place of the sample solution, 2.5 MH ₂ SO ₄ in that the addition of a volume equal to the volume of the sample solution, which corresponds to the fraction of 1 M solution of MgSO ₄ Was used.

The extinction coefficient e _M was determined by a calibration curve according to Bouguer-Lambert A = (A ⁵⁴⁰ - A ⁵⁴⁰ k) = e _M lc, where A ⁵⁴⁰ Is the optical density of the analyte complex with PAR at 540 nm, A ⁵⁴⁰ _k is the optical density of the control solution with PAR at 540 nm, e _M is the molar extinction coefficient, 1 is the optical path, c is the concentration of V (IV) which is a vanadyl ion that forms a complex with PAR. PAR is present in sufficient excess. Experimally measured e _M is e _M ⁵⁴⁰ = 3.57 10 ⁴ lx mol ^-1 x cm ^-1 , which is described in J. Schneider, l JCsanyi (ed. ) For PAR complexes with V (V) in the concentration range 0.1-1.2 mkg / , Mikcohimica Acta, 1976, coincides with the II, 271-282] the ^{_{e M 545 = 3.45 10 4 lx}} mol -1 x cm -1 reported.

To demonstrate the above-described determination of vanadium ions in the presence of sulfuric acid and magnesium sulfate, certain control studies with vanadium standard solutions were performed. That is, 10 mkl of a standard VOSO ₄ solution (1 mg / ml) was added to a 10 ml volumetric flask set, each containing 1 ml of 1 M Na-acetate buffer (pH 6.5), 0.5 ml of 0.1% ₂ contains a 1 M MgSO ₄ 0 to 0.8 ml of SO _4. A corresponding equivalent volume of 5 M NaOH (i.e., 0 to 0.8 ml) was added to each flask for neutralization. After mixing the reagents, the volume of the sample was adjusted to 10 ml with distilled water (twice distilled). The pH of the obtained sample was adjusted within the range of 6.2 to 6.5. The determination of the value of A = (A ⁵⁴⁰ - A ⁵⁴⁰ k) obtained under different contents of MgSO ₄ and H ₂ SO ₄ is based on the measurement of vanadium, which is sulfuric acid (final concentration up to 0.25 M) And does not affect the accuracy and correctness of the signal.

The concentration of V (IV) in the complex with PAR was calculated from the Buerger-Lambert equation using the experimentally determined optical density A ⁵⁴⁰ and A ⁵⁴⁰ _k and experimentally determined extinction coefficient. To determine the concentration of V (IV) in the half-cell that has passed through the membrane, ie, MgSO ₄ , a dilution of the sample in the preparation of the complex with PAR was considered as follows: C _{V (IV)} = C _{meas X} V _flask / V _sample , where C _{V (IV)} is the vanadium ion concentration in the half cell containing magnesium sulfate, C _meas is the measured vanadium concentration in the complex with PAR, and V _flask is the concentration The volume of the volumetric flask used (usually 10 ml) and V _sample is the volume of the fraction added to the volumetric flask taken from the half-cell with MgSO ₄ to make the complex with PAR.

The permeability (P) of the membrane to the vanadium (IV) ion is described in Chuankun Jia, Jianguo Liu, Chuanwei Yan. (2) given in Journal of Power Sources, 2010, 195, 4380-4383 :

(T) / t = S x P / L (c _A - c (t)), (2)

Here, P is the membrane permeability (cm ² min ^-1 ), V is the volume of solution in the half-cell containing magnesium sulfate (0.8 ml in this case), c (t) ₄ , < / RTI > the concentration of vanadium in the half-

t is the time represented by minutes,

S is the membrane area in contact with the solution (S = 0.785 cm < ² > in this case)

L is the thickness (cm) of the film,

c _A is the initial concentration of vanadium ion in the half-cell containing VOSO ₄ (1 M).

Naturally, the rate of dispersion of ions through the membrane depends on the difference in their concentration on both sides of the membrane, and therefore decreases with time. Therefore, the transmission value calculated from the relational expression (2) is leveled with time. In cases where the permeability of the membrane is low, the rate of ion dispersion over time can be estimated to be almost constant ( J. Xi et al., J. Mater. Chem., 2008, 18, 1232-12314) .

The thickness of the film was measured in micrometers.

Films according to some embodiments of the present invention have a permeability to low vanadium ions. Vanadyl ion permeability is measured when transmittance of VO ²⁺ 6x10 ^-7 cm ² min ^-1 or less, 5x10 ^-7 cm ² min ^-1 or less, more preferably from 1x10 ^-7 cm ² min ^-1 or less, and further preferably 1 x 10 ^-9 cm ² min ^-1 or less, still more preferably ¹ x ^{10 -10} cm ² min ^-1 or less.

In membranes according to embodiments of the present invention, the number of cationic groups of cationic surfactant per anionic group (e.g., sulfo group) in the membrane is from about 0.01 to about 2, preferably from about 0.2 to about 1, more preferably from about 0.5 to about 1.

The thickness of the film can be determined depending on the purpose.

According to the present invention, surfactant modification results in a significant reduction in membrane ionic conductivity.

One embodiment of the present invention can be applied to the construction and manufacturing method of a vanadium redox battery known in the art except that the film is included. The vanadium redox battery includes: an anode electrolyte reservoir for storing an anode electrolyte, supplying an anode electrolyte to the anode, and storing an anode electrolyte discharged from the anode; a cathode electrolytic solution storing unit for supplying the cathode electrolytic solution to the cathode; And a cathode electrolytic solution reservoir for containing the discharged cathode electrolytic solution.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in more detail in the following examples, but the details described herein are not to be construed as limitations.

Example

Example 1 (Comparative Example)

The Nafion membrane (Nafion 117, DuPont) was continuously treated in distilled water (1 hour), 3% H ₂ O ₂ (1.5 hours), distilled water (1 hour), 0.5 MH ₂ SO ₄ ≪ / RTI > The permeability of the membrane to the ion V (IV) was measured using the method described above. The thickness of the membrane swollen in water or in 2.5 MH ₂ SO ₄ was 60 micrometers. The concentrations of vanadium ions in the half cell containing MgSO ₄ were 28 mM and 47 mM, respectively, within 30 minutes and 60 minutes after the cell filling. The average permeability of the membranes calculated by equation (2) was 6.2 × 10 ^-6 cm ² / min (30 min incubation) and 5.2 × 10 ^-6 cm ² min ^-1 (the packed cells were incubated at room temperature for 60 min) . The ion conductivity of the membrane was measured by a standard impedance spectroscopy method and was 0.1 S / cm.

Example 2

A water-swollen Nafion membrane (Nafion 1110, DuPont) having a size of about 4 x 3 cm was prepared as described in Example 1, placed in 20 ml of 10 mM dodecyltrimethylammonium chloride solution and allowed to stand at room temperature for 16 hours. The membrane was then thoroughly washed with distilled water twice distilled and placed in a cell for measurement of the permeability to vanadium. Within exactly one week, the solution from the half-cell containing magnesium sulfate was quantitated and transferred to a 10 ml volumetric flask, the reagents needed for the determination of the vanadium concentration according to the procedure described above were added, the volume was adjusted to 10 ml , The solution was thoroughly stirred, the pH of the product (pH = 6.4) was adjusted, and the degree of absorption was measured. The concentration of vanadium ions in the half-cell containing MgSO ₄ was 0.1 mM. The thickness of the after-reforming film was 65 micrometers. The membrane permeability calculated using equation (2) was 6.6 × 10 ^-11 cm ² / min. The ionic conductivity of the membrane was 0.003 S / cm.

Example 3

Nafion 117 (Nafion 117) was prepared as described in Example 1. The prepared membrane (approximately 3 x 3 cm) was placed in 15 ml of a 15 mM solution of dodecylamine hydrochloride. That is, 10 g DDA (dodecylamine) was mixed with 15 ml twice distilled water and then adjusted to pH 2 by addition of concentrated HCl solution. The vials were placed in an incubator and incubated at 50 ^° C for one day to dissolve the surfactant. The membrane was placed in a glass bottle containing the surfactant solution and maintained in a thermostat at 50 ^° C for 7 days. The membrane permeability was measured as described in Example 2. After 7 days of cell loading, the vanadium concentration in the half-cell containing MgSO ₄ was 0.06 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 3.94 × 10 ^-11 cm ² / min. The ionic conductivity of the membrane was 0.0017 S / cm.

Example 4

The effect of the incubation time of the membrane in the cationic surfactant solution on the permeability to vanadium ion was studied. To this end, five samples of Nafion-117 membrane (about 4 x 3 cm) prepared as described in Example 1 were placed in 15 ml of 10 mM undidazolopyridinium bromide solution and incubated at room temperature for 1 hour, 3 hours, 5 hours, 16 hours and 24 hours. The membrane was washed with water and the permeability was measured as described in Example 2. [ The measurement results are summarized in Table 1.

Membrane processing time After sampling the cell, VO ²⁺ concentration in the half-cell with MgSO ₄ , mM Transmittance, cm ² / min 1 hours 3 hours 12 4.4 × 10 ^-7 3 hours 3 days 0.3 4.6 × 10 ^-10 5 hours 7 days 0.6 3.9 × 10 ^-10 16 hours 7 days 0.6 3.9 × 10 ^-10 24 hours 7 days 0.3 2.0 × 10 ^-10

The data show that incubation of the membrane in a 10 mM solution of cationic surfactant for only 3 hours reduces the permeability to vanadium by about 10 times compared to the native unmodified Nafion membrane.

Example 5

The effect of the degree of membrane modification on the permeability of the membrane to vanadyl ions was evaluated. The Nafion-117 membrane sample thus prepared was modified with a cationic surfactant, cetyl pyridinium chloride (CPC), and the concentration of the cationic surfactant in the solution was measured by absorbance at a maximum of l = 259 nm Can be measured spectrophotometrically (molar extinction coefficient = e _m 4100 l mol ^-1 cm ^-1 ).

The experiment was carried out as follows. Three of the membrane samples each having a weight of about 0.1 g (scale 2 x 2 cm) were placed in individual glass bottles containing 5 ml of distilled water twice and different amounts of CPC.

To measure the absolute amount of sulfo-residues (moles) in each sample of the membrane, the water content in the swollen membrane sample was measured by drying the swollen membrane sample to a constant weight at 50 ^° C. The water content of the previously prepared Nafion-117 membrane in the swollen state in water was 25%. Considering the fact that the gram equivalent of Nafion 117, corresponding to the dry weight of Nafion per sulfometry, is 1100, the absolute amount of sulfation in the sample of each membrane was as follows:

[SO ₃ H] _membrane = 0.1 g × 0.75 / 1100 g / mol = 6.82 × 10 ^-5 mol.

Assuming that all of the sulfo groups in the membrane can bind to ions of the cationic surfactant, 1.36 ml of 10 mM CPC (molar ratio of sample No. 1, [CPC] / [SO ₃ ] = 0.2), 3.4 ml of 10 mM CPC (Molar ratio of Sample No. 2, [CPC] / [SO ₃ ] = 0.5) and 6.82 ml of 10 mM CPC (molar ratio of Sample No. 3, [CPC] / [SO ₃ ] = 1.0) were added to the samples. The concentration of CPC in solution was measured spectrophotometrically for each solution within 2 and 5 days. The amount of surfactant _bound [cS] _bound to the membrane was determined by the decrease in CPC concentration in the surrounding medium.

Within 2 days, most of the surfactant was adsorbed to the membrane (residual CPC concentration in solution did not exceed 2% of the added amount.

Thus, three samples of the modified membrane having the degree of modification (filling) of the membrane D = [cS] _bound / [SO ₃ H] of 0.2, 0.5 and 1 were obtained and the membrane permeability And membrane ion conductivity. The results are summarized in Table 2.

Degree of filling of membrane Sampling moment after cell loading VO ²⁺ concentration in the half-cell with MgSO ₄ , mM Transmittance cm ² / min Membrane ion conductivity Unmodified membrane 0.5 hours 28 6.2 × 10 ^-6 0.1 0.2 2 hours 10 5.5 × 10 ^-7 0.09 0.5 3 days 6 9.2 × 10 ^-9 0.017 One 7 days 0.1 6.6 × 10 ^-11 0.0016

The data presented above show that even at low fill (D = 0.2), the permeability of the film to vanadium ions is reduced by almost a factor of ten. Equimolar binding of surfactant of surfactant (1 surfactant ion per 1 sulfonyl group of membrane) reduces permeability about 100,000 times.

Example 6

A Nafion membrane (Nafion 1100, DuPont) was prepared as described in Example 1. A water-swollen membrane having a size of about 4 x 3 cm was prepared, placed in 15 ml of a 15 mM solution of dodecylpyridinium chloride, and allowed to stand at room temperature for 16 hours. The membrane permeability was measured as described in Example 2. Cell loading and half-cell vanadium concentration containing MgSO ₄ within 21 days was 3 mM. The thickness of the swollen modified membrane was 65 micrometers. The membrane permeability calculated using equation (2) was 6.6 × 10 ^-10 cm ² / min. The ionic conductivity of the membrane was 0.0017 S / cm.

Example 7

A Nafion membrane (Nafion 1110, DuPont) was prepared as described in Example 1. A prepared membrane having a size of about 3 x 3 cm was placed in 15 ml of a 10 mM solution of cetylpyridinium chloride and incubated at about 100 ^° C for 7 hours. The membrane permeability was measured as described in Example 2. After 7 days of cell loading, the concentration of vanadium in the half-cell with MgSO ₄ was 0.1 mM. The film thickness was 65 micrometers. The membrane permeability calculated using equation (2) was 6.6 × 10 ^-11 cm ² / min. The ionic conductivity of the membrane was 0.0016 S / cm.

Example 8

A Nafion membrane (Nafion 1110, DuPont) was prepared as described in Example 1. The prepared membrane (approximately 3 x 3 cm) was placed in 15 ml of 70 mM cetyltrimethylammonium bromide solution and incubated at about 50 ^° C for 48 hours. The membrane permeability was measured as described in Example 2. After cell loading, and 430 hours (about 18 days), having a half MgSO ₄ - cells in the vanadium concentration was 0.089 mM. The membrane permeability calculated using equation (2) was 2.3 × 10 ^-11 cm ² / min.

Example 9

The Nafion-117 (Nafion-117) was prepared as described in Example 1. The prepared membrane (approximately 3 x 4 cm) was placed in 10 ml of Praepagen HY solution. As indicated by the manufacturer, Praepagen HY has the formula R ₁ R ₂ R ₃ R ₄ N ⁺ X ^- , where R ₁ = R ₂ = CH ₃ , R ₃ = (CH ₂ ) ₂ OH, R ₄ = C (Wt) of a mixture of _{10 to 20} alkyl, a mixture of C ₁₂ (about 65-70%) and C ₁₄ (about 23-28%), a cationic surfactant with X = Cl. To prepare a solution, 75 ml of a 40% solution of Praepagen HY was added to 10 ml of distilled 2-times distilled water.

The membrane was placed in the solution prepared above and kept at room temperature for 20 hours. The membrane permeability was measured as described in Example 2. After 7 days of cell loading, the concentration of vanadium in the half-cell with MgSO ₄ was 0.5 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 3.3 × 10 ^-10 cm ² / min. The ionic conductivity of the membrane was 0.0017 S / cm.

Example 10

The binding stability of the cationic surfactant to the membrane was studied. For this purpose, the membrane obtained according to Example 6 was incubated in 50 ml of twice distilled water for 2 weeks. The amount of desorbed surfactant (dodecylpyridinium chloride, DDPC) was measured spectrophotometrically (e _M = 4100 l mol ^-1 cm ^-1 ). The DDPC concentration in the solution was 1.5 x 10 < ^-5 > M, which corresponds to a desorption degree of less than 1%. Membrane permeability calculated using the formula (2) did not change compared to the initial modified membrane of Example 6, it was ^{6.6 × 10 -10 cm 2 / min} .

Example 11

The effect of the high temperature on the binding stability of the cationic surfactant to the membrane was studied. For this purpose, the membrane obtained according to Example 6 was boiled in 100 ml of distilled water for 1 hour. The concentration of DDPC in the solution could not be determined by spectrometry, indicating that the degree of desorption was less than 1%. The membrane permeability calculated using equation (2) did not change and was 6.6 × 10 ^-10 cm ² / min.

Example 12

The effect of preparation in sulfuric acid on cationic surfactant / membrane binding was studied. For this purpose, the membrane prepared according to Example 6 was continuously boiled in 40 ml of distilled water twice distilled for 1 hour at 40 ml of 0.5 MH ₂ SO ₄ for 1 hour. The membrane permeability calculated using Eq. (2) was 1.6 × 10 ^-9 cm ² / min, or about 2.4 times greater than that of the original unmodified membrane.

Example 13

A Nafion membrane (Nafion 1110, DuPont) was prepared as described in Example 1. The prepared membrane (about 3 x 3 cm) was placed in 15 ml of 10 mM cetylpyridinium chloride solution and allowed to stand at room temperature for 2 hours. Fully washing the membrane with water, and was annealed for 24 hours at 150 ^o C. The membrane After overnight incubation in 50 ml of twice distilled water, its permeability was measured as described in Example 2. After 7 days of cell loading, the vanadium concentration in the half-cell with MgSO ₄ was 0.1 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 6.6 × 10 ^-11 cm ² / min.

Example 14

A Nafion membrane (Nafion 1100, DuPont) was prepared as described in Example 1. The water-swollen membrane (0.23 g) was placed in 20 ml of 0.005 M didecyldimethylammonium bromide ([cS] / [SO ₃ H] _berm = 0.7) and incubated at room temperature for 36 hours. The membrane permeability was measured as described in Example 2. Cell loading, and 11 days later, half having MgSO ₄ - vanadium concentration in the cell was 0.9 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 4.0 × 10 ^-10 cm ² / min. The ionic conductivity of the membrane was 0.0017 S / cm.

Example 15

A Nafion membrane (Nafion-1100) was prepared as described in Example 1. The water-swollen prepared membrane having a weight of 0.29 g was placed in 20 ml of 0.005 M of didecyldimethylammonium bromide solution ([cS] / [SO ₃ H] _membr = 0.55) and incubated at room temperature for 24 hours. The membrane permeability was measured as described in Example 2. After 4 days of cell loading, the vanadium concentration in the half-cell with MgSO ₄ was 0.03 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 3.5 × 10 ^-11 cm ² / min.

Example 16

The Nafion-117 (Nafion-117) was prepared as described in Example 1. The water-swelled membrane (0.22 g) was placed in 30 ml of 0.01 M didecyldimethylammonium bromide solution ([cS] / [SO ₃ H] _mem = 2) and incubated at room temperature for 24 hours. The membrane permeability was measured as described in Example 2. It was the vanadium concentration in the cell is 0.06 mM - cell loading and after 11 days (261 hours), the half with MgSO _4. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 2.3 × 10 ^-11 cm ² / min.

Example 17

A Nafion membrane (Nafion 1110) was prepared as described in Example 1. The water-swollen membrane (0.22 g) was placed in 30 ml of 0.005 M didecyldimethylammonium bromide solution ([cS] / [SO ₃ H] _membr = 1.02) and incubated at 50 ^° C for 24 hours . The membrane permeability was measured as described in Example 2. After 11 days of cell loading, the vanadium concentration in the half-cell with MgSO ₄ was 0.13 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 5.5 × 10 ^-11 cm ² / min. The ionic conductivity of the membrane was 0.001 S / cm.

Example 18

To prepare 30 ml of 0.01 M decylamine solution in 0.01 M acetic acid, the surfactant sample was placed in a 0.01 M acetic acid solution and kept at 50 ^° C overnight to dissolve the surfactant. Nafion-117 (0.17 g) of the water-swollen, prepared membrane was placed in 30 ml of 0.01 M decylamine solution in 0.01 M acetic acid and maintained at 50 ^° C for one week. The membrane permeability was measured as described in Example 2. The membrane permeability calculated using equation (2) was 1.2 × 10 ^-10 cm ² / min.

Example 19

A Nafion membrane (Nafion 1100, DuPont) was prepared as described in Example 1. The water-swollen prepared membrane (0.19 g) was placed in 20 ml of 0.005 M dioctadecyldimethylammonium bromide solution ([cS] / [SO ₃ H] _membr = 0.76) and incubated at 50 ^° C for 36 hours. The membrane permeability was measured as described in Example 2. Cell loading, and 22 days later, half having MgSO ₄ - vanadium concentration in the cell was 15.5 mM. The film thickness was 65 mkm. The membrane permeability calculated using equation (2) was 7.2 × 10 ^-8 cm ² / min.

Claims (21)

Introducing the cationic surfactant into at least a portion of the membrane surface and the membrane by incubating the membrane in an aqueous or saline solution containing a mixture of the cationic surfactant or the cationic surfactant, How to reduce. The method of claim 1, wherein the membrane is a cation exchange membrane. The method according to claim 1, wherein the membrane is a polymer membrane having a sulfo group. The method of claim 1, wherein the membrane has a permeability of vanadyl VO ²⁺ ion reduced by at least 5-fold relative to the native unmodified membrane after introducing the cationic surfactant into the membrane. The method of claim 1, wherein the cationic surfactant has a hydrophobic moiety and the membrane comprises a hydrophobic fragment. The method according to claim 1, further comprising the step of successively heating the membrane in a hydrogen peroxide solution, in a sulfuric acid solution, and in distilled water before, after, or after introduction of the cationic surfactant. The method according to claim 1, wherein the membrane comprises a polymer having a sulfo group and at least one other polymer. The method of claim 1, wherein the cationic surfactant comprises a compound represented by the following formula (1) or a mixture thereof:
[Chemical Formula 1]

(2)

In the above formulas (1) and (2)
R < ₁ > is hydrogen, methyl or ethyl,
R ₂ is hydrogen, methyl, ethyl, phenyl, phenylmethyl, hydroxymethyl or hydroxyethyl,
R ₃ is selected from the group consisting of hydrogen, C ₁ to C ₂₀ alkyl, C ₆ to C ₂₀ aryl, C ₇ to C ₂₀ arylalkyl, C ₁ to C ₂₀ hydroxyalkyl, (CH ₂ CH ₂ O) _n R, Or (CH ₂ ) _p COO ^- , wherein n is an integer from 4 to 100, R is hydrogen or C ₁ to C ₂₀ alkyl, p is an integer from 1 to 12,
R ₄ is C ₈ to hydroxyalkyl, -COOR a C ₂₀ alkyl, C ₈ to C ₂₀ of - ", wherein R '', R" COOR "'or-R" OCOR "and R"' is C ₈ To C ₂₀ alkyl, and R "is C ₁ to C ₃ alkylene;
R ₅ is C ₈ to alkyl, -COOR of C ₂₀ - ", wherein R '', R" COOR "'or-R" OCOR "and R" a "is alkyl of from C ₈ to C _20, R" is C ₁ to C ₃ alkylene;
X is an anion group. The method of claim 1, wherein the cationic surfactant comprises a surfactant having a double tail, amphoteric betaine, or a surfactant having a hydroxy group in the side chain. The method of claim 1, wherein the incubation is performed at a temperature of from 100 ^° C to 10 ^° C. The method according to claim 1, wherein the concentration of the cationic surfactant in the aqueous or saline solution is 10 < ^-5 > M to 1 m. The method of claim 1, wherein the aqueous or saline solution further comprises at least one of an inorganic salt, an organic salt, an alkali metal ion, an inorganic acid, and an organic acid. A vanadium redox battery comprising an anode, a cathode, and a separator provided between the anode and the cathode, wherein the separator is a film produced by the method according to any one of claims 1 to 12. A separator provided between the anode and the cathode, wherein the separator is a membrane comprising a cationic surfactant or a mixture of the cationic surfactants on at least a portion of the surface of the membrane and the inside of the membrane, wherein the vanadium redox battery. 15. The vanadium redox battery according to claim 14, wherein the ratio of the number of cationic groups of the cationic surfactant bound to the membrane per sulfo group in the membrane is 0.01 to 2. 15. The vanadium redox battery of claim 14, wherein the membrane is a cation exchange membrane. 15. The vanadium redox battery according to claim 14, wherein the film is a polymer film having a sulfurizing group. 15. The vanadium redox battery of claim 14, wherein the cationic surfactant has a hydrophobic moiety and the membrane comprises a hydrophobic fragment. 15. The vanadium redox battery according to claim 14, wherein the membrane comprises a polymer having a sulfo group and at least one other polymer. The vanadium redox battery according to claim 14, wherein the cationic surfactant comprises a compound represented by the following formula 1 or 2, or a mixture thereof:
[Chemical Formula 1]

(2)

In the above formulas (1) and (2)
R < ₁ > is hydrogen, methyl or ethyl,
R ₂ is hydrogen, methyl, ethyl, phenyl, phenylmethyl, hydroxymethyl or hydroxyethyl,
R ₃ is selected from the group consisting of hydrogen, C ₁ to C ₂₀ alkyl, C ₆ to C ₂₀ aryl, C ₇ to C ₂₀ arylalkyl, C ₁ to C ₂₀ hydroxyalkyl, (CH ₂ CH ₂ O) _n R, Or (CH ₂ ) _p COO ^- , wherein n is an integer from 4 to 100, R is hydrogen or C ₁ to C ₂₀ alkyl, p is an integer from 1 to 12,
R ₄ is C ₈ to hydroxyalkyl, -COOR a C ₂₀ alkyl, C ₈ to C ₂₀ of - ", wherein R '', R" COOR "'or-R" OCOR "and R"' is C ₈ To C ₂₀ alkyl, and R "is C ₁ to C ₃ alkylene;
R ₅ is ', wherein R' C ₈ to C ₂₀ alkyl, -COOR ', -R "COOR"' or -R "OCOR" a and R "a" is alkyl of from C ₈ to C _20, R "is C ₁ to C ₃ alkylene;
X is an anion group. 15. The vanadium redox battery of claim 14, wherein the cationic surfactant comprises a surfactant having a double tail, amphoteric betaine, or a surfactant having a hydroxy group in the side chain.