WO2017086546A1 - Electrolyte solution for redox flow battery, and redox flow battery containing same - Google Patents

Abstract

The present invention relates to: an electrolyte solution for a redox flow battery, comprising a solute and a solvent, wherein the solute comprises at least one of organic materials substituted with a functional group, which chemically and electrochemically reacts stably, and thus a larger amount thereof is dissolved in an electrolyte, thereby enabling a large capacity per volume to be expressed; and a redox flow battery containing the same.

Description

Electrolyte for redox flow battery and redox flow battery containing same

The present invention relates to an electrolyte for a redox flow battery and a redox flow battery comprising the same, and more particularly, to an electrolyte solution for a redox flow battery comprising a solute and a solvent, wherein the solute is chemically and electrochemically stable Substituted compounds having a functional group capable of dissolving a large amount of the electrolyte in the electrolytes and capable of expressing a large capacity per unit volume, and a redox flow cell comprising the same.

With the development of personal IT devices and the reliance on electric energy due to the development of the information society, the technology to efficiently store and utilize this energy is becoming essential. In particular, as new renewable energy sources are emerging as a source of power to replace petroleum, it is necessary to supply stable power through this power generation system. In order to efficiently supply power through existing power generation facilities, ESS) is getting attention with the importance of smart grid.

Here, a redox flow battery, which is a secondary battery having a long service life in addition to its economical efficiency, is in the spotlight. Unlike conventional lithium and sodium secondary batteries, in the redox flow battery, the capacitive expression mechanism in which the active material is dissolved in the solvent and the active material is subjected to the redox reaction through the redox reaction in the anode and the cathode, I have.

Since the active material of the electrode melts in the solvent and reacts, the standard reduction potential of the redox pair of the active material dissolving in the electrolyte used as the negative electrolyte and the positive electrolyte is different, The operating voltage of the cell is determined.

Also, since the capacity is expressed by the oxidation-reduction reaction of the electrolyte supplied from the external tank, there is an advantage that the capacity of the entire cell can be easily controlled by adjusting the size of the external storage tank. In addition to this, the redox reaction of the active redox couples occurs on the surface of the anode and the cathode, so that the electrode has less physical deformation than the conventional ion-based battery, and thus the life characteristic is excellent.

Vanadium-based salts and water have been mainly used as active materials and solvents for redox flow batteries. Typical examples are all vanadium redox flow batteries, which are prepared by dissolving vanadium salts in both electrolytic solution and negative electrolytic solution. However, in the case of the medium and large-sized energy storage system, the point that is not influenced by the surrounding environment, that is, the temperature, and the operating voltage are important characteristics. Thus, improvement of the existing water system is required.

All vanadium-based batteries show some drawbacks because they use water as a solvent. The first is that when the cell is driven at a potential higher than 1.23 V, which is the water potential window, electrolyte loss due to solvent decomposition occurs. That is, this is a limit point for the operating voltage. The next point is that it is difficult to drive below 0 ° C due to the thermodynamic properties of water. In addition, there is a disadvantage due to the active material of the entire vanadium-based battery, which is caused by the high temperature precipitation of the cathode active material. The most prevalent sulfuric acid-based active vanadium-based redox flow cell has been found to precipitate 5-valent vanadium at V ₂ O ₅ at about 40 ° C in the M. Skyllas-Kazacos 1990 paper JOURNAL OF APPLIED ELECTROCHEMISTRY , 20 , 463-467.

Due to this property, the concentration of the solute directly connected to the capacity of the electrolytic solution of the all-vanadium-based redox flow cell based on sulfuric acid is disadvantageous because of this precipitation. This problem is pointed out as a disadvantage in the application of medium and large power storage systems in which high reliability and high capacity are important along with high capacity and long life.

Organic solvents have been proposed as a solvent for a redox flow cell, which can take advantage of 1.5 to 2 times the driving voltage in order to improve the energy density in comparison with existing water system. In the redox flow cell using the organic solvent as the electrolyte solvent, the limit of the selection of the redox pair generated due to the decomposition voltage of water and the limit of the driving temperature due to the freezing point of the water are relatively small And there are no disadvantages such as precipitation of vanadium salt at high temperature, and therefore research is actively conducted. However, according to research conducted in conventional, the active material than the conventional water-based systems, i.e. 2013, the disadvantage of the solubility in solvents of the oxidation-reduction pair significantly lower by W. Wang Advanced Functional years. Materials, 23 , 970-986, and the case where the difference between the standard reduction potentials of the cathode active material and the anode active material is smaller than that of the aqueous system, and the improvement is not emphasized, is disclosed by Sleightholme in Journal of power sources , 196 , ≪ / RTI > 5742-5745. In order to solve this problem, it is necessary to constitute the system so that a large amount of oxidation-reduction groups are dissolved in the solvent and the difference in the standard reduction potential of the dissolved substance is wider than that of the aqueous system.

Therefore, a large amount of oxidation-reduction groups are dissolved in a large amount in a solvent, and the difference in the standard reduction potential of the dissolved substance is higher than that of the aqueous system, and the solubility of the organic material is much larger than that of the previously- Development of an electrolytic solution having a high energy density as well as stable lifetime characteristics is demanded.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a redox flow battery having improved solubility in solvents due to functional groups of the solute It is possible to dissolve a larger amount of solute in the solvent as compared with the redox flow battery, to exhibit a capacity per unit volume, to have a low redox potential, to be applicable to an anode material for a non-aqueous flow cell, And a redox flow battery including the electrolyte solution.

According to an aspect of the present invention, there is provided an electrolytic solution for a redox flow battery comprising a solvent and a solute, wherein the solute is at least one organic compound selected from a phthalimide compound represented by the following formula (1) Organic material ').

[Chemical Formula 1]

(Wherein R ₁ represents a group selected from the group consisting of an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a bromopropyl group, CH ₂ Ph (Ph = phenyl group), a benzyl group, a butoxycarbonylmethyl group , A carboxylmethyl group and an aminocarbonylmethyl group, and X is selected from H, F, Cl, Br and I.)

In the electrolytic solution for a redox flow battery of the present invention, the solvent may be an aqueous solvent, an organic solvent, or a mixture thereof.

In the electrolytic solution for a redox flow battery according to the present invention, the aqueous solvent may be at least one selected from sulfuric acid, hydrochloric acid and phosphoric acid, and the organic solvent may include acetonitrile, dimethyl carbonate, diethyl carbonate, dimethylsulfoxide, dimethyl It may be at least one selected from formamide, propylene carbonate, ethylene carbonate, N -methyl-2-pyrrolidone, fluoroethylene carbonate, gamma butyl lactone, tetraethylene glycol dimethyl ether, ethanol and methanol.

In the electrolyte solution for a redox flow battery according to the present invention, the electrolyte solution may further include a supporting electrolyte.

In the electrolytic solution for a redox flow battery according to the present invention, the supporting electrolyte may be at least one selected from the group consisting of an alkyl ammonium salt, a lithium salt and a sodium salt.

The alkyl ammonium _{^{salt, PF 6 -, BF 4 -}} , AsF 6 -, ClO 4 -, CF 3 SO 3 -, CF 3 SO 3 -, C (SO 2 CF 3) 3 -, N (CF 3 SO 2) ₂ ^- and CH (CF ₃ SO ₂ ) ₂ ^- , and a combination of ammonium cations in which alkyl is methyl, ethyl, butyl or propyl in the tetraalkylammonium cation.

The lithium _{salt, LiPF 6, LiBF 4, LiAsF} 6, LiClO 4, LiCF 3 SO 3, LiCF 3 SO 3, LiC (SO 2 CF 3) 3, LiN (CF 3 SO 2) 2 , and LiCH (CF ₃ SO ₂ ) < ₂ >

The sodium _{salt, NaPF 6, NaBF 4, NaAsF} 6, NaClO 4, NaCF 3 SO 3, NaCF 3 SO 3, NaC (SO 2 CF 3) 3, NaN (CF 3 SO 2) 2 , and NaCH (CF ₃ SO ₂ ) < ₂ >

In the redox flow battery electrolyte according to the present invention, the solubility of the organic substance in the electrolyte solution may be a 0.1 M~ 10 M.

In the electrolytic solution for the redox flow battery according to the present invention, the voltage difference between the oxidation reaction and the reduction reaction between the negative electrode electrolyte dissolved in the solvent using the organic material as the negative electrode active material and the positive electrode active material dissolved in the solvent may be 1.4 V or higher.

When the electrolytic solution containing the organic substance having the concentration of 0.01 M in the electrolytic solution for the redox flow battery according to the present invention was confirmed by the cyclic voltammetric method at a scanning rate of 300 mV s ^-1 , The difference (E _pa -E _pc ) at which the peak current of the reaction and the reduction reaction are confirmed can be 0.5 V or less.

In the electrolyte for a redox flow battery according to the present invention, the organic material may be used as a negative electrode active material.

Next, a redox flow battery according to the present invention is characterized by including an electrolyte solution for a redox flow battery according to the present invention.

In the redox flow battery according to the present invention, the solubility of the organic material may be 0.1 M to 10 M.

In the redox flow battery according to the present invention, the organic material may be used as a negative electrode active material.

The redox flow battery according to the present invention may include a negative electrolyte containing the organic material as a negative electrode active material, and a positive electrode active material including a positive electrode active material.

In the redox flow battery according to the present invention, the voltage difference between the oxidation reaction and the reduction reaction between the negative electrode electrolyte in which the negative electrode active material containing the organic substance is dissolved in the solvent and the positive electrode active material in which the positive electrode active material is dissolved in the solvent may be 1.4 V or more.

In the redox flow battery according to the present invention, the cathode active material may be at least one selected from a metal-ligand compound and an organic compound that performs a redox reaction.

In the redox flow battery according to the present invention, an electrolyte solution containing the metal-ligand compound may be used as a positive electrode, and an electrolyte solution containing the organic compound may be used as a negative electrode.

In the redox flow battery according to the present invention, an electrolyte solution containing the organic compound that performs the oxidation-reduction reaction may be used as a positive electrode, and an electrolyte solution containing the organic compound may be used as a negative electrode.

According to the electrolyte solution for a redox flow battery produced by dissolving a chemically and electrochemically stably reacting organic material in a solvent as a solute in accordance with the present invention, unlike the prior art, by applying an optimal solute to a redox flow battery, A larger amount of solute can be dissolved in a solvent as compared with a redox flow battery, a capacity per unit volume can be manifested, a difference in reaction voltage of the redox pair is large, an operating voltage is high, and a battery having a high energy density can be realized There is an advantage.

In addition, by using the optimal solute and solvent for the redox flow battery, it is possible to realize a remarkably high operating voltage as compared with the conventional aqueous system, and the solubility of the organic material is much larger than that of the conventional organic electrolyte, It is possible to provide an electrolytic solution having a high energy density and a high operating voltage.

In addition, the electrolytic solution for the redox flow battery of the present invention exhibits stable lifetime characteristics without decomposition of the material even when the redox reaction is repeated due to the stable electrochemical reaction, and also prevents mutual contamination, A battery having a life characteristic can be designed.

FIG. 1 is a graph showing a current-voltage curve by a circulating current-voltage method using the electrolyte of Example 1. FIG.

2 is a graph showing a current-voltage curve by a circulating current-voltage method using the electrolyte of Example 2. FIG.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

The electrolytic solution for a redox flow battery according to the present invention comprises a solvent and a solute, and the solute includes at least one organic material selected from phthalimide compounds represented by the following general formula (1).

[Chemical Formula 1]

(Wherein R ₁ represents an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a bromopropyl group, a CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, Aminocarbonylmethyl group, and X is selected from H, F, Cl, Br and I.)

In the electrolytic solution for a redox flow battery of the present invention, when a phthalimide compound is constituted by such a substituent as described above, the solubility is increased by the effect of the substituent and the effect of increasing the capacity can be exhibited. It is difficult to electrochemically reduce the number of molecules, and in the case of a compound applicable to an anode active material, the operation voltage is shifted to a negative side so that a higher working potential is secured Substituents based on hydrocarbons are also capable of this role, which can increase the solubility and further improve the energy density.

In the electrolytic solution for a redox flow battery of the present invention, the solvent to dissolve the organic material may be an aqueous solvent, an organic solvent, or a mixture thereof.

In order to maximize solubility of the organic material, the aqueous solvent may be at least one selected from sulfuric acid, hydrochloric acid and phosphoric acid. The organic solvent may be at least one selected from the group consisting of acetonitrile, dimethyl carbonate, diethyl carbonate, dimethylsulfoxide, , Propylene carbonate, ethylene carbonate, N -methyl-2-pyrrolidone, gamma butyl lactone, fluoroethylene carbonate, ethanol and methanol.

In the present invention, a supporting electrolyte may be further added in order to additionally impart conductivity to the electrolytic solution. The supporting electrolyte may be at least one selected from the group consisting of an alkylammonium salt, a lithium salt, and a sodium salt.

The alkyl ammonium _{^{salt, PF 6 -, BF 4 -}} , AsF 6 -, ClO 4 -, CF 3 SO 3 -, CF 3 SO 3 -, C (SO 2 CF 3) 3 -, N (CF 3 SO 2) ₂ ^- and CH (CF ₃ SO ₂ ) ₂ ^- , and a combination of ammonium cations in which alkyl is methyl, ethyl, butyl or propyl in the tetraalkylammonium cation.

The lithium _{salt, LiPF 6, LiBF 4, LiAsF} 6, LiClO 4, LiCF 3 SO 3, LiCF 3 SO 3, LiC (SO 2 CF 3) 3, LiN (CF 3 SO 2) 2 , and LiCH (CF ₃ SO ₂ ) < ₂ >

The sodium _{salt, NaPF 6, NaBF 4, NaAsF} 6, NaClO 4, NaCF 3 SO 3, NaCF 3 SO 3, NaC (SO 2 CF 3) 3, NaN (CF 3 SO 2) 2 , and NaCH (CF ₃ SO ₂ ) < ₂ >

In the electrolytic solution for a redox flow battery of the present invention, the solubility of the organic material is preferably 0.1 M to 10 M , and more preferably 1.1 M to 10 M. When the solubility of the organic material is less than 0.1 M , the energy density is extremely low, so that it is difficult to realize the effect of the present invention. When an electrolyte having an excessively high solubility of more than 10 M is produced, Precipitation of organic matter in the supersaturated solution may occur.

In the electrolyte for a redox flow battery according to the present invention, the organic material may be used as a negative electrode active material.

The cathode active material may be at least one selected from a metal-ligand compound and an organic compound that performs a redox reaction.

Examples of the metal-ligand compound include, but are not limited to, metal-acetylacetonate-based materials, metal-biphenyl-based materials, and metal-tetradentate tetradecane-based materials have.

There are no particular restrictions on the oxidation-reduction organic compound, and any compound applicable to a cathode active material having a high voltage capable of being oxidized by losing electrons can be used.

In the electrolytic solution for the redox flow battery of the present invention, the organic material may be used as a negative electrode active material, and at least one selected from the metal-ligand and the organic compound that performs the redox reaction may be used as the positive electrode active material. It is preferable that the operating voltage obtained from the oxidation and reduction of the organic solvent should be higher than 1.23 V, which is the maximum working voltage of the water system, in terms of energy density.

Thus, the maximum reduction potential of the cathode electrolyte Fc / Fc + (ferrocene / ferro when titanium) compared to the reference electrode, respectively -0.8 ~ -2.0 V, and the maximum oxidation potential of the anode electrolyte Fc / Fc ⁺ standard electrode more positive than 0 V against And the voltage difference between the oxidation reaction and the reduction reaction between the negative electrode electrolyte dissolved in the solvent as the negative electrode active material and the positive electrode active material dissolving the positive electrode active material in the solvent is preferably 1.4 V or more.

In addition, all redox pairs are highly electrochemically reversible so that the difference between the oxidation potential and the reduction potential should be small. Otherwise, the voltage difference at the time of charge and discharge in the complete construction becomes large, and energy efficiency may be lowered. Accordingly, the difference in peak potential between the anode active material and the cathode active material, in which oxidation and reduction reactions occur, must be small.

Therefore, in the present invention, an electrolytic solution containing the organic substance as a solute having a concentration of 0.01 M by a cyclic voltammetry, which is the most typical electrochemical analysis method for confirming this, is oxidized at a scanning rate of 300 mV s ^-1 When the reduction reaction is confirmed, it is preferable that the difference (E _pa -E _pc ) at which the peak currents of the oxidation reaction and the reduction reaction are confirmed to be 0.5 V or less.

In the electrolytic solution for a redox flow battery according to the present invention, the electrolytic solution may be used by combining two different electrolytic solutions having different dissolved solutes, with a separating film interposed therebetween.

Next, a redox flow battery according to the present invention is characterized by including an electrolyte solution for a redox flow battery containing the organic material according to the present invention.

In the redox flow battery according to the present invention, the solubility of the organic material may be 0.1 M to 10 M.

In the redox flow battery according to the present invention, the voltage difference between the oxidation reaction and the reduction reaction between the negative electrode electrolyte in which the negative electrode active material containing the organic material is dissolved in the solvent and the positive electrode solution in which the positive electrode active material is dissolved in the solvent may be 1.4 V or more .

In the redox flow battery according to the present invention, the organic material may be used as a negative electrode active material.

In the redox flow battery according to the present invention, the cathode active material may be at least one selected from a metal-ligand compound and an organic compound that performs a redox reaction.

In the redox flow battery according to the present invention, an electrolyte solution containing the metal-ligand compound may be used as a positive electrode, and an electrolyte solution containing the organic compound may be used as a negative electrode.

In the redox flow battery according to the present invention, an electrolyte solution containing the organic compound that performs the oxidation-reduction reaction may be used as a positive electrode, and an electrolyte solution containing the organic compound may be used as a negative electrode.

That is, the present invention provides an electrolyte solution for a redox flow cell including a solvent and a solute, wherein the solute includes the organic compound which is a compound that chemically and electrochemically stably reacts, wherein at least one electron moves during the reaction, An electrolyte for a redox flow cell in which organic matter is stably dissolved in a solvent and does not cause precipitation in an electrolyte, and a redox flow battery using the same.

In order to demonstrate the superiority of the electrolytic solution for a redox flow battery of the present invention and the redox flow battery comprising the same according to the present invention, various experiments of the present invention and a comparative example have been carried out.

Examples 1 to 4 and Comparative Examples 1 to 2

Example 1. ( N - (3-bromopropyl) phthalimide)

0.01 M of N - (3-bromopropyl) phthalimide purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetrafluoroborated tetraethyl ammonium to prepare an electrolytic solution.

Example 2. ( N - an electrolytic solution containing butyl phthalimide)

0.01 M of N -butylphthalimide purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetra-fluoroborated tetraethyl ammonium to prepare an electrolytic solution.

Example 3. ( N - (3-bromopropyl) phthalimide Solubility experiment)

N - (3-bromopropyl) phthalimide purchased from Sigma-Aldrich was dissolved in a propylene carbonate solution containing tetrafluoroborated tetraethylammonium as much as possible to prepare an electrolytic solution.

Example 4. ( N - Solubility test of butylphthalimide)

N -butylphthalimide purchased from Sigma-Aldrich was dissolved in a propylene carbonate solution containing tetraethylboron tetrafluoroborate as much as possible to prepare an electrolytic solution.

Comparative Example 1. ( N - an electrolyte solution containing methylphthalimide)

0.01 M of N -methylphthalimide purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetrafluoroborated tetraethyl ammonium to prepare an electrolytic solution.

Comparative Example 2. ( N - Solubility test of methylphthalimide)

N -methylphthalimide purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetra-fluoroborated tetramethylammonium fluoride as much as possible to prepare an electrolytic solution.

Cyclic Voltammetry

[Confirmation of Reaction Voltage of Electrolyte]

Using an electrolytic solution obtained in Example 1-2, and a potential scan rate 300 mV s ^- it was carried out an experiment on a 1. Ferrocene was used as an internal reference for precise voltage determination in the organic electrolyte solution. A glacier carbon electrode was used as the working electrode and platinum was used as the counter electrode. The electrochemical cell was constructed using these materials and the cyclic voltammetry experiment was carried out.

[Determination of Reaction Voltage of Negative Active Material]

In the case of Example 1, it was confirmed that the oxidation voltage and the reduction voltage were -1.75 V and -1.87 V, respectively. Through these two reactions, it was confirmed that the redox voltage could be used as an anode active material of the redox flow cell having -1.81 V Respectively.

In the case of Example 2, it was confirmed that the oxidation voltage and the reduction voltage were -1.83 V and -1.96 V, respectively. Through these two reactions, it was confirmed that the redox voltage could be used as an anode active material of a redox flow cell having a -1.90 V Respectively.

[Determination of material life characteristics]

Experiments were conducted using the electrolytes obtained in Examples 1 and 2 at a potential scanning speed of 300 mV s ^-1 . Ferrocene was used as a reference electrode for accurate voltage determination in the organic electrolytic solution. A glacier carbon electrode was used as a working electrode and platinum was used as a counter electrode. An electrochemical cell was constructed using these electrodes, .

As a result of the experiment, although the reaction was repeated 50 times each time the redox pair was oxidized and reduced, no decrease in the current value due to the change of the reaction voltage and the irreversible reaction was found in the electrolytes of Examples 1 and 2.

[Comparison of voltage and energy density using electrolyte solubility and half-wave potential]

The results of the maximum solubility experiments (Examples 3 to 4 and Comparative Example 2) of the electrolytes of Examples 1 to 2 and Comparative Example 1 and the values similar to E ⁰ for the electrolytes of Examples 1 to 2 and Comparative Example 1 The half-wave potential, which can be assumed to have, is shown in Table 1. The energy density was compared through the driving voltage and the solubility of the cell in which this and Comparative Example 1 were combined with a cathode material of 0.56 V ( vs. Fc / Fc ⁺ ). The comparison results of energy density are shown in Table 2 below.

	Solubility / M	restoration
		Half-wave potential / V ( vs. Fc / Fc + )
Examples 1 and 3	1.3	-1.81
Examples 2 and 4	5	-1.90
Comparative Examples 1 and 2	0.5	1.08

As shown in Table 1, when the reaction voltage and the solubility of the organic substance into which the functional group is introduced according to the present invention were changed in the electrolyte prepared by applying the same organic solvent, when used as the electrolyte of the redox flow cell, Can be designed. In the case of such an organic material, the higher the solubility in the organic solvent is, the more advantageous it is to have a solubility of 0.2 M or more, and the solubility to 0.4 M or more is more preferable.

It is preferable that the difference between the equilibrium potential of the ferrocene is -0.9 to -2.44 V ( vs. Fc / Fc ⁺ ) because the solvent used can be decomposed by reduction if the reaction voltage is too negative.

Combination	Solubility / M	1 electron	Energy density / W h L -1
		Operating Voltage / V
Examples 1 and 3	1.3	2.37	41.29
Examples 2 and 4	5	2.46	164.83
Comparative Examples 1 and 2	0.5	1.39	18.62

As shown in Table 2, in Comparative Example 1 (Comparative Example 1) in which the organic materials of Examples 1 and 2 were driven under the same system as a cell composed of an anode material containing anode active material and 0.56 V ( vs. Fc / Fc ⁺ ) cathode material It can be seen that Examples 1 and 2 containing an organic material having a functional group according to the present invention exhibit higher solubility and exhibit a significantly higher energy density than Comparative Example 1. [

Claims (17)

1. An electrolytic solution for a redox flow cell, wherein the electrolytic solution includes a solvent and a solute, and the solute includes at least one organic material selected from a phthalimide-based compound represented by the following formula (1)

   [Chemical Formula 1]

   

   (Wherein R ₁ represents an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a bromopropyl group, a CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, Aminocarbonylmethyl group, and X is selected from H, F, Cl, Br and I).
2. The method according to claim 1,

   Wherein the solvent is an aqueous solvent, an organic solvent, or a mixture thereof.
3. 3. The method of claim 2,

   The organic solvent is at least one selected from the group consisting of acetonitrile, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, dimethylformamide, propylene carbonate, ethylene carbonate, N -methyl- Wherein the electrolytic solution is at least one selected from the group consisting of 2-pyrrolidone, fluoroethylene carbonate, gamma-butyllactone, tetraethylene glycol dimethyl ether, ethanol and methanol.
4. The method according to claim 1,

   Wherein the electrolytic solution further comprises a supporting electrolyte.
5. 5. The method of claim 4,

   Wherein the supporting electrolyte is at least one selected from the group consisting of an alkylammonium salt, a lithium salt, and a sodium salt.
6. 6. The method of claim 5,

   The alkyl ammonium _{^{salt, PF 6 -, BF 4 -}} , AsF 6 -, ClO 4 -, CF 3 SO 3 -, CF 3 SO 3 -, C (SO 2 CF 3) 3 -, N (CF 3 SO 2) ₂ ^- and CH (CF ₃ SO ₂ ) ₂ ^- and an alkyl cation in the tetraalkylammonium cation in combination with an ammonium cation such as methyl, ethyl, butyl or propyl .
7. 6. The method of claim 5,

   The lithium _{salt, LiPF 6, LiBF 4, LiAsF} 6, LiClO 4, LiCF 3 SO 3, LiCF 3 SO 3, LiC (SO 2 CF 3) 3, LiN (CF 3 SO 2) 2 , and LiCH (CF ₃ SO ₂ ) < _{2 &} gt ;. _{2. The} electrolytic solution for a redox flow battery according to claim 1,
8. 6. The method of claim 5,

   The sodium _{salt, NaPF 6, NaBF 4, NaAsF} 6, NaClO 4, NaCF 3 SO 3, NaCF 3 SO 3, NaC (SO 2 CF 3) 3, NaN (CF 3 SO 2) 2 , and NaCH (CF ₃ SO ₂ ) < _{2 &} gt ;. _{2. The} electrolytic solution for a redox flow battery according to claim 1,
9. The method according to claim 1,

   Wherein the solubility of the organic material in the electrolyte solution is 0.1 M to 10 M.
10. The method according to claim 1,

    Wherein the voltage difference between the oxidation reaction and the reduction reaction between the negative electrode active material dissolved in the solvent and the positive electrode active material dissolved in the solvent is not less than 1.4 V. 2. The electrolytic solution for a redox flow cell according to claim 1,
11. The method according to claim 1,

    0.01 M having a concentration of the redox reaction to determine when the electrolytic solution containing the organic matter in a circular current-voltage law to the scan rate 300 mV s ^-1, a (Peak current), each of the peak current of oxidation and reduction reactions _Wherein the difference (E _pa -E _pc ) of the voltage to be verified is 0.5 V or less.
12. The method according to claim 1,

    Wherein the organic material is a negative electrode active material.
13. 12. A redox flow battery comprising an electrolyte solution for a redox flow battery according to any one of claims 1 to 12.
14. 14. The method of claim 13,

    Wherein the battery comprises a negative electrode electrolyte in which the organic material is dissolved in a solvent as a negative electrode active material, and a positive electrode active material in which the positive electrode active material is dissolved in a solvent.
15. 15. The method of claim 14,

    Wherein the cathode active material is at least one selected from a metal-ligand compound and an organic compound that performs a redox reaction.
16. 16. The method of claim 15,

    Wherein the electrolyte solution containing the metal-ligand compound is used as a positive electrode, and the electrolyte solution containing the organic compound is used as a negative electrode.
17. 16. The method of claim 15,

    Wherein an electrolyte solution containing the organic compound that performs the oxidation-reduction reaction is used as a positive electrode, and an electrolyte solution containing the organic compound is used as a negative electrode.

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