KR101864710B1 - Crown ether-inclusive electrolyte for redox flow batteries and method of manufacturing the same - Google Patents

Abstract

The electrolytic solution for a redox flow battery provided in the present invention includes a crown ether compound. Accordingly, it is possible to provide an electrolytic solution for a redox flow battery having high solubility of active material and stable at high temperature and high pH and having excellent electrochemical characteristics.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for a redox flow battery including a crown ether additive,

The present invention relates to an electrolyte solution for a redox flow battery and a method for producing the same. More particularly, the present invention relates to an electrolyte solution for a redox flow cell containing a crown ether compound and a method for producing the same.

As demand for mass storage devices increases, research on redox flow cells is accelerating. The redox flow battery can charge and discharge electrical energy as the active materials dissolved in the aqueous or organic electrolyte solution oxidize and reduce at the surface of the electrode. The energy density of the redox flow battery depends on the solubility of the active material. However, the solubility of the active material is limited. In particular, when the battery is operated at a high temperature and a high pH, irreversible precipitation, side reaction and gas may be generated, so that the oxidation and reduction reaction of the active material is limited, . In addition, since the crossover phenomenon may occur in which the active material or water of the electrolyte passes through the separation membrane between the electrodes and moves to the opposite electrode, the efficiency of the battery may be greatly reduced.

U.S. Patent Application Publication No. 2014-0028260 U.S. Patent Application Publication No. 2013-0224538 U.S. Patent No. 8,753,761 U.S. Patent No. 8,642,202 U.S. Patent No. 8,628,880 U.S. Patent No. 7,258,947 U.S. Patent No. 7,078,123

It is an object of the present invention to provide an electrolytic solution for a redox flow battery having high solubility of active material, high energy density and excellent electrochemical activity over existing solubility limits and a method for producing the same.

Another object of the present invention is to provide a method of preparing an electrolyte solution for a redox flow battery which is stable without causing precipitation, irreversible side reaction, and gas generation even at high temperature and high pH, and which prevents crossover of active material and has long- .

An electrolyte solution for a redox flow battery according to exemplary embodiments to accomplish an object of the present invention comprises a crown ether compound.

In exemplary embodiments, the electrolytic solution for the redox flow battery is an electrolytic solution for a redox flow battery of an aqueous or non-aqueous solvent, and further includes a metal ion active material or an organic molecular active material. The crown ether compound may form a complex with the active material.

In exemplary embodiments, the crown ether compound may include less than 0.3 wt% to less than 5 wt%, based on the total weight of the electrolytic solution for the redox flow battery.

In exemplary embodiments, the crown ether compound may include crown ethers, crown ether analogues, or crown ether derivatives.

In exemplary embodiments, the crown ether analog is a compound wherein at least one oxygen on the crown ether ring is substituted with at least one element selected from the group consisting of nitrogen (N), sulfur (S), phosphorus (P) ≪ / RTI >

In exemplary embodiments, the crown ether derivative is a crown ether having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, an amine group, a thiol group, a carbonyl group, Or crown ethers combined with at least one hydrocarbon compound via covalent bonds.

In a method of manufacturing an electrolyte solution for a redox flow battery according to exemplary embodiments for achieving an object of the present invention, a first electrolyte in which an active material is dissolved is prepared. A crown ether compound is added to the first electrolyte to prepare a second electrolyte.

In exemplary embodiments, the second electrolyte may be supplied into the redox flow cell. The redox flow battery can be charged or discharged.

In exemplary embodiments, the redox flow cell may be a unit cell, a half cell, a cell having an asymmetric electrode, a large area cell, or a stack cell.

In exemplary embodiments, the crown ether compound may comprise less than 0.3 wt% to less than 5 wt%, based on the total weight of the second electrolyte.

The electrolyte solution for a redox flow battery of the present invention has a high active material solubility by including a crown ether compound, thereby providing a redox flow battery having high energy density and electrochemical activity.

In addition, since the electrolyte for redox flow battery of the present invention is stable at the time of battery operation, particularly at high temperature and high pH, irrespective of irreversible precipitation and gas generation in the electrolyte even when the redox flow battery is driven for a long time, In addition, the crossover phenomenon may not occur.

1 shows a complex structure formed by a crown ether compound and an active material according to an embodiment of the present invention.
2 shows the structure of a redox flow battery applicable to the present invention.
3 is a graph comparing the solubility of the active material of the electrolyte according to Examples 1, 4, and 7 of the present invention and the solubility of the active material of the electrolyte according to Comparative Example 1. Fig.
4 is a graph showing electrochemical characteristics of Examples 1 to 3 and Comparative Example 1 of the present invention measured using a cyclic voltammetry (CV).
5 is a graph showing electrochemical characteristics of Examples 4 to 6 and Comparative Example 1 of the present invention measured using a cyclic voltammetry (CV) method.
6 is a graph showing electrochemical characteristics of Examples 7 to 9 and Comparative Example 1 of the present invention measured using a cyclic voltammetry (CV).
Fig. 7 shows the results of evaluating the effect of suppressing the precipitation of the positive electrode electrolyte according to Examples 10 to 12 and Comparative Examples 2 to 3 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the invention disclosed in the text are illustrative only for the purpose of illustration and implementations of the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims, As will be understood by those skilled in the art.

A redox flow battery is a battery capable of separating an electrode responsible for an output and an electrolyte responsible for a capacity, and means a battery storing electric energy using a specific oxidation-reduction potential and a difference therebetween. The redox flow battery includes not only a unit cell but also a half cell, a cell having an asymmetric electrode, a large area cell and a cell having a large stack structure.

Adding a crown ether compound or producing a solution containing a crown ether compound means that the crown ether compound is uniformly dissolved in an electrolyte solution for a redox flow cell to produce a homogenous solution.

The fact that the crown ether compound forms a complex with the active material means that the crown ether compound interacts with the active material through an intermolecular force in the electrolyte to form a complex.

The improvement in the electrochemical properties of the electrolyte for the redox flow battery means that as the value of each reaction current increases in the oxidation-reduction reaction, more chemokines participate in the reaction and the reversibility increases, and the gap between the oxidation- Which means that the overpotential is reduced.

The formation of irreversible precipitates means that some chemical species react to form precipitation depending on the temperature when the redox flow cell is driven.

Redox Flow  Battery electrolyte

The electrolytic solution for a redox flow battery of the present invention includes a crown ether compound, an active material and a solvent. At this time, the crown ether compound acts as a ligand to form a chelate-type stable complex with the active material. Due to the formation of the complex, a new chemical equilibrium can be created in the electrolyte, and the chemical equilibrium constant for complex formation (K _f ) can be determined by interaction with the solubility parameter (K _sp ) A new dissolution equilibrium can be created in the electrolyte (K = K _sp x K _f ). As a result, the solubility of the electrolyte in the active material can be increased.

Further, at the time of complex formation, the active material can be stably dissolved in the electrolytic solution and sufficiently oxidized and reduced. That is, even at high temperature and high pH, the active material may decompose or not bind with other ions in the electrolyte, thereby suppressing precipitation and gas generation due to non-reversible side reactions.

Further, since the ion radius of the active material forming the complex is increased, the crossover phenomenon can be suppressed in the electrolyte solution. Therefore, the capacity of the redox flow battery gradually decreases during driving, and there is no problem that the balance of the electrolyte concentration between the two electrodes or the balance of the volume is changed.

Therefore, the electrolyte for redox flow battery of the present invention has high active material solubility and is stable at high temperature and high pH and has excellent electrochemical characteristics. Therefore, when the redox flow battery is operated at high temperature and high pH for a long time, May not be lowered and may be improved.

In exemplary embodiments, the crown ether compound may include crown ethers, crown ether analogues, or crown ether derivatives.

Crown ether is a cyclic polyether linked with a 1,2-ethane diol as a basic unit, and can be represented by the formula of n-crown -m, wherein n and m are each an integer of 2 or more. The crown ethers applicable to the present invention are not particularly limited, but may be, for example, 18-crown-6, 15-crown-5 or 12-crown-4.

The crown ether analogue may be one in which at least one oxygen on the crown ether ring is substituted with an element such as nitrogen (N), sulfur (S), phosphorus (P), boron (B) That is, the crown ether analog may include azacrown ether and thiacrown ether, for example monoaza-12-crown-3.

The crown ether derivative may be a crown ether having at least one functional group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, an amine group, a thiol group, a carbonyl group or an amide group, and examples thereof include hydroxy-12- Lt; / RTI >

Alternatively, the crown ether derivative may be a crown ether bonded with at least one hydrocarbon compound through ionic or covalent bonding. Here, the hydrocarbon compound is not particularly limited and may be a chain saturated hydrocarbon compound, a chain unsaturated hydrocarbon compound, a cyclic compound, an aromatic cyclic compound, a heterocyclic compound, or an aromatic heterocyclic compound. The heterocyclic compound and the aromatic heterocyclic compound may contain oxygen (O), nitrogen (N), boron (B), sulfur (S), phosphorus (P), fluorine (F) (I) or chlorine (Cl). The crown ether derivative may be, for example, benzo-12-crown-4 or dibenzo-12-crown-4.

In exemplary embodiments, the crown ether compound may include from 0.3% by weight to less than 5% by weight based on the total weight of the electrolytic solution for the redox flow battery. When the crown ether compound is contained in an amount of less than 0.3% by weight, irreversible side reactions in the electrolyte may not be sufficiently inhibited, and precipitation and gas may be generated, thereby deteriorating the performance of the redox flow battery. Alternatively, when the crown ether compound is contained in an amount of 5 wt% or more, crown ether complex ions may be contained in an excessive amount in the electrolyte to interfere with the oxidation and reduction reaction of the active material, thereby degrading the electrochemical performance of the redox flow battery .

In the exemplary embodiments, the active material is not particularly limited as long as it can perform a reversible oxidation-reduction reaction and form a stable complex in the form of a chelate form with the crown ether compound, but may include a metal ion or an organic molecule .

The active material capable of providing a metal ion may be at least one selected from the group consisting of magnesium (Mg), aluminum (Al), phosphorus (P), sulfur (S), chlorine (Cl), calcium (Ca) The number of typical metals such as Ge, Ar, Selenium, Br, In, Sn, Iodine, Pb, Or a metal such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, Pd, Ag, Cd, W, Iridium, Pt, Au, mercury (Hg), uranium (U), and the like.

Such an active material capable of providing an organic molecule may be selected from the group consisting of, for example, ascorbic acid and its derivatives, guanidine and derivatives, flavin and its derivatives, quinone and its derivatives, Pteridine and derivatives thereof.

In one embodiment, the active material may be a vanadium ion, and the crown ether compound may be 18-crown-6. In this case, the unpaired electron pair of the oxygen atom of 18-crown-6 acts as a ligand to form a coordination bond with the vanadium ion. As a result, as shown in FIG. 1, a complex can be formed in the most thermodynamically stable structure have. Referring to FIG. 1, oxygen atoms (100) and carbon atoms (200) and vanadium ions (300) of 18-crown-6 may be combined in the structure as shown in FIG.

On the other hand, the complex structure may vary depending on the kind of the crown ether compound and the type of the active material (ion size and charge of the active material).

In exemplary embodiments, the solvent may include at least one of an aqueous solvent or an organic solvent. That is, the solvent may be an aqueous solvent or an organic solvent, and may be mixed with an aqueous solvent or an organic solvent, depending on the case where the solubility of the active material is to be further increased.

The water-based solvent applicable as the solvent is not particularly limited, but may include, for example, at least one of sulfuric acid, hydrochloric acid or phosphoric acid.

Examples of the organic solvent applicable as the solvent include, but are not limited to, acetonitrile, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, dimethylformamide, propylene carbonate, ethylene carbonate and N-methyl- , And fluoroethylene carbonate.

Alternatively, in exemplary embodiments, the solvent may be daily for the ionic liquid.

Manufacturing method of electrolyte for redox flow battery

The electrolytic solution for a redox flow battery of the present invention can be produced by performing the following processes.

First, a first electrolyte in which an active material is dissolved is prepared.

In exemplary embodiments, the first electrolyte may be prepared by dissolving the active material in a solvent. The solvent and the active material may be the same as described above.

Thereafter, a crown ether compound is added to the first electrolyte solution to prepare a second electrolyte solution. At this time, the crown ether compound may form a chelate-type complex with the active material in the second electrolyte. Accordingly, an electrolytic solution for a redox flow cell of the present invention in which the crown ether compound is dissolved at a uniform concentration can be produced, which can be provided to the redox flow battery as a positive electrode electrolyte solution or a negative electrode electrolyte solution.

In exemplary embodiments, the crown ether compound may be the same as described above, and may be added in an amount of 0.3 to 5 wt% based on the total weight of the second electrolyte.

As described above, by adding the crown ether compound to the first electrolyte in which the active material is dissolved, irreversible precipitation, generation of gas and occurrence of crossover phenomenon can be suppressed with high solubility of active material and redox flow An electrolyte for a battery can be easily produced.

Alternatively, the electrolytic solution for the redox flow battery of the present invention can be produced by carrying out substantially the same or similar processes as the above-described processes.

First, the first electrolyte is prepared by performing the same process as described above, and the second electrolyte is prepared. Then, the second electrolyte is supplied into the redox flow cell.

The redox flow cell may have substantially the same or similar structure as shown in Fig. 2, for example. That is, the redox flow cell includes a positive electrode cell 1, a negative electrode 2, a positive electrode 3, a negative electrode 4, an ion exchange membrane 5, positive and negative electrode electrolyte tanks 11 and 12, Pumps 13 and 14 and pipes 15 and 16 and the second electrolyte may be supplied into the redox flow battery using positive and negative electrolyte tanks 11 and 12. [

Thereafter, the redox flow battery is charged or discharged. As a result, a positive electrode electrolyte solution containing a crown ether compound may be generated in the positive electrode 3, and a negative electrode electrolyte solution containing a crown ether compound may be generated in the negative electrode 4. At this time, the positive electrode and the negative electrode active material may form stable complexes with the crown ether compound and the chelate form, respectively, in the positive and negative electrode electrolytes.

As described above, by supplying the second electrolyte containing the crown ether compound into the redox flow cell and charging or discharging the battery, it is possible to suppress the occurrence of irreversible precipitation, generation of gas and crossover phenomenon with high active material solubility Thereby providing a positive electrode electrolyte and a negative electrode electrolyte having excellent electrochemical characteristics to the positive electrode and the negative electrode, respectively.

The present invention will be described in more detail through the following embodiments. However, the examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Example 1]

294.2 g of sulfuric acid (H ₂ SO ₄ ) was mixed with distilled water to prepare a mixed solution having a total volume of 1.0 L. Considering the large difference in density between sulfuric acid and distilled water, the mixture was thoroughly mixed for 30 minutes thereafter. To the aqueous 3 mol / L sulfuric acid solution thus prepared, 244.5 g of vanadyl sulfate (VOSO ₄ ) was added and stirred for 1 hour. Thus, a first electrolyte having a vanadium concentration of 1.5 mol / L was prepared. Thereafter, 26.4 g of 18-crown-6 was added to the first electrolyte and sufficiently stirred to prepare an electrolytic solution for a redox flow cell having a crown ether compound concentration of 0.1 mol / L.

[Example 2]

An electrolyte solution for a redox flow cell having a crown ether compound concentration of 0.01 mol / L was prepared by carrying out the same processes as in Example 1, except that 2.64 g of 18-crown-6 was added to the first electrolyte solution.

[Example 3]

An electrolyte solution for a redox flow cell having a crown ether compound concentration of 0.001 mol / L was prepared by carrying out the same processes as in Example 1, except that 0.264 g of 18-crown-6 was added to the first electrolyte solution.

[Example 4]

The procedure of Example 1 was repeated except that 22.0 g of 15-crown-5 was added to prepare an electrolyte solution for a redox flow battery having a crown ether compound concentration of 0.1 mol / L.

[Example 5]

An electrolyte solution for a redox flow cell having a concentration of the crown ether compound of 0.01 mol / L was prepared by performing the same process as in Example 4, except that 2.20 g of 15-crown-5 was added to the first electrolyte solution.

[Example 6]

An electrolyte solution for a redox flow cell having a crown ether compound concentration of 0.001 mol / L was prepared by carrying out the same processes as in Example 4, except that 0.22 g of 15-crown-5 was added to the first electrolyte solution.

[Example 7]

The procedure of Example 1 was repeated except that 17.6 g of 12-crown-4 was added to prepare an electrolytic solution for a redox flow battery having a crown ether compound concentration of 0.1 mol / L.

[Example 8]

An electrolyte solution for a redox flow cell having a concentration of crown ether compound of 0.01 mol / L was prepared by carrying out the same processes as in Example 7 except that 1.76 g of 12-crown-4 was added to the first electrolyte solution.

[Example 9]

An electrolytic solution for a redox flow cell having a crown ether compound concentration of 0.001 mol / L was prepared by carrying out the same processes as in Example 7 except that 0.176 g of 12-crown-4 was added to the first electrolyte solution.

[Example 10]

The same process as in Example 1 was carried out to prepare a first electrolyte. After assembling the redox flow battery, the first electrolyte was evaluated. In the redox flow cell, a carbon felt is inserted in both the cathode and the anode, and a Nafion separator is inserted between the electrodes. The carbon felt is separated from the separator plate made of graphite plate and the metal plate And was assembled so as to have a contact structure. Thereafter, 7.69 g of 18-crown-6 was mixed with the first electrolyte to prepare a second electrolyte having a uniform concentration, which was then flowed into the redox flow cell at a flow rate of 50 mL / min. The redox flow cell was charged at a current density of 50 mA / cm ^{2 and} the SOC (state of charge) was set to 100%. As a result, all the vanadium ions were charged, and a VO ₂ ⁺ type pentavalent electrolytic solution containing 0.5 wt% of 18-crown-6 was produced in the cathode. In the anode, 0.5 wt% - V ^{2 +} form of divalent vanadium electrolyte containing crown-6 was produced.

[Example 11]

By carrying out the same process as in Example 10, except that 11.54 g of 18-crown-6 was mixed with the first electrolyte, the cathode had a VO ₂ ^{+ -type} of 0.75 wt% 18-crown- A 5-valent vanadium electrolyte was produced, and a divalent vanadium electrolyte in the form of V ^{2 +} containing 18-crown-6 at 0.75 wt% was produced in the anode.

[Example 12]

By carrying out the same process as in Example 10 except that 15.39 g of 18-crown-6 was mixed with the first electrolyte, the cathode had a VO ₂ ⁺ form of 18 wt% crown-6 A 5-valent vanadium electrolyte was produced, and a divalent vanadium electrolyte in the form of V ^{2 +} containing 1.0 wt% 18-crown-6 was produced in the anode.

[Example 13]

By carrying out the same process as in Example 10, except that 7.69 g of 15-crown-5 was added, the cathode was doped with 0.5 mass% of 5-valent vanadium electrolyte in VO ₂ ⁺ form containing 15- And a divalent vanadium electrolyte in the form of V ^{2 +} containing 15-crown-5 at 0.5 wt% was produced in the anode.

[Example 14]

By carrying out the same process as in Example 10 except that 7.69 g of 12-crown-4 was added, the cathode was doped with 0.5 wt% 12-crown-4 in a VO ₂ ⁺ form of pentavalent vanadium electrolyte And a divalent vanadium electrolyte in the form of V ^{2 +} containing 12-crown-4 at 0.5 wt% was produced in the anode.

[Comparative Example 1]

The same procedure as in Example 1 was carried out except that 18-crown-6 was added to prepare an electrolyte solution for a redox flow cell containing no crown ether compound.

[Comparative Example 2]

By performing the same process as in Example 10, except that 3.85 g of 18-crown-6 was mixed with the first electrolyte, the cathode had a VO ₂ ^{+ -type} form containing 18-crown-5 at 0.25 wt% A 5-valent vanadium electrolyte was produced, and a divalent vanadium electrolyte in the form of V ^{2 +} containing 15-crown-5 at 0.25 wt% was produced in the anode.

[Comparative Example 3]

By performing the same process as in Example 10 except that 18-crown-6 was mixed with the first electrolyte, a VO ₂ ^{+ -type} pentavalent non-crown vanadium electrolyte containing no crown ether compound was produced at the cathode , And a divalent vanadium electrolyte in the form of V ^{2 +} without a crown ether compound was produced at the anode.

Evaluation of solubility of active material in electrolyte for redox flow battery

In order to evaluate the solubility of the active material in the redox flow battery electrolyte, the solubility of the electrolytic solution according to Examples 1, 4, and 7 was compared with the solubility of the vanadium salt of the electrolytic solution according to Comparative Example 1.

Referring to FIG. 3, it was confirmed that a larger amount of the vanadium salt was dissolved in the electrolytes according to Examples 1, 4, and 7 including the crown ether compound than the electrolyte according to Comparative Example 1 not containing the crown ether compound . Thus, it can be seen that the solubility of the active material in the redox flow cell electrolyte can be improved by including the crown ether compound, and a redox flow battery having a high energy density can be provided by using the crown ether compound.

Depending on the type and concentration of crown ether compounds Redox Flow  Evaluation of Electrochemical Activity of Electrolyte for Battery

In order to evaluate the electrochemical characteristics of the electrolyte solution for the redox flow cell according to the kind and concentration of the crown ether compound, the electrochemical characteristics of the electrolyte solution of 0.06 to 1.6 V (ws.) At 10 mV / sec of the potentials of Examples 1 to 9 and Comparative Example 1 were measured. Ag / AgCl) was performed.

Referring to FIGS. 4 to 6, as the concentration of the crown ether compound was increased, the current width was increased, and the reversibility of the oxidation-reduction reaction was increased. In addition, it was confirmed that the difference between the oxidation-reduction potentials was reduced, and the overvoltage was reduced and the voltage efficiency was increased. Accordingly, it can be seen that as the crown ether compound is dissolved at a high concentration, the electrolytic solution for the redox flow battery can have a high electrochemical activity and can be used to provide a redox flow battery with high efficiency.

Depending on the weight of the crown ether compound Redox Flow  Evaluation of stability of battery electrolyte

Examples 10 to 12 and Comparative Examples 2 to 3 were allowed to stand at a temperature of 40 캜 for 6 hours to confirm the precipitation, in order to evaluate the stability of the electrolytic solution for the redox flow cell according to the weight of the crown ether compound.

Referring to FIG. 7, it was confirmed that precipitation did not occur in Examples 10 to 12, but precipitation occurred in Comparative Examples 2 and 3. Accordingly, when the crown crown ether compound is contained in an amount of not less than 0.3% by weight and less than 5% by weight based on the total weight of the electrolytic solution for redox flow battery, the stability of the active material in the electrolyte is increased while maintaining the activity of the electrolyte, Can be suppressed.

Anode and cathode cells: 1, 2
Anode and cathode: 3, 4
Ion exchange membrane: 5
Positive and Negative Electrolyte Tanks: 11, 12
Positive and Negative Pumps: 13, 14
Pipe: 15, 16
Oxygen atoms: 100
Carbon atoms: 200
Vanadium ion: 300

Claims (10)

An electrolyte solution for a redox flow cell comprising a crown ether compound,
The electrolytic solution for a redox flow battery is an electrolytic solution for a redox flow battery in an aqueous or nonaqueous solvent, and further includes an active material containing vanadium ions,
The crown ether compound forms a complex with the active material containing the vanadium ion,
Wherein the crown ether compound comprises at least one selected from the group consisting of 18-crown-6, 15-crown-5 and 12-crown-4. An electrolyte solution for a redox flow cell comprising a crown ether compound,
The electrolytic solution for a redox flow battery is an electrolytic solution for a redox flow battery in an aqueous or nonaqueous solvent, and further includes an active material containing vanadium ions,
The crown ether compound forms a complex with the active material containing the vanadium ion,
The crown ether compound is obtained by substituting at least one oxygen on the crown ether ring of the crown ether with at least one element selected from the group consisting of nitrogen (N), sulfur (S), phosphorus (P) and boron (B)
Wherein the crown ether comprises at least one selected from the group consisting of 18-crown-6, 15-crown-5 and 12-crown-4. 3. The method according to claim 1 or 2,
Wherein the crown ether compound is contained in an amount of 0.3 wt% to less than 5 wt% based on the total weight of the redox flow battery electrolyte. A process for producing an electrolyte solution for a redox flow battery according to claim 1 or 2,
Preparing a first electrolyte in which an active material containing vanadium ions is dissolved; And
And adding a crown ether compound to the first electrolyte solution to prepare a second electrolyte solution. 5. The method of claim 4,
Supplying the second electrolyte into the redox flow cell; And
Further comprising the step of charging or discharging the redox flow battery. 6. The method of claim 5,
Wherein the redox flow cell is a unit cell, a half cell, a cell having an asymmetric electrode, a large area cell, or a stacked cell. 5. The method of claim 4,
Wherein the crown ether compound is contained in an amount of 0.3 wt% to less than 5 wt% based on the total weight of the second electrolyte solution. delete delete delete

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