KR20160148111A - Electrolyte for redox flow battery and redox flow battery including the same - Google Patents

Abstract

The present invention relates to an electrolyte for redox flow batteries, and to a redox flow battery including the same. The electrolyte for redox flow batteries and the redox flow battery including the same involve the use of an organic substance which is dissolved in both positive electrodes and negative electrodes, as an optimal solvent (an active material, an oxidation-reduction pair) for the redox flow batteries, thereby exhibiting remarkably high driving voltage compared to those of existing water-based systems. In addition, based on solubility greater than those of exiting non-water (organic) systems, energy density of the redox flow batteries remarkably increases as well.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrolyte for a redox flow battery and a redox flow battery including the redox flow battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte for a redox flow battery and a redox flow battery including the redox flow battery. More particularly, the present invention relates to an electrolyte for a redox flow battery, By using an organic material, it is possible to realize a remarkably high operating voltage as compared with the conventional water-based system, and the solubility of the redox flow cell is remarkably improved compared to the conventional non-aqueous organic system, And a redox flow battery comprising the electrolyte.

As the development of personal IT devices due to the development of information society and the reliance on electric energy have increased, a technology for efficiently storing and utilizing this energy is essential.

Particularly, the amount of electric energy used is increasing rapidly, and the energy storage system (ESS) is attracting attention with the importance of smart grid for efficient use of generated electric energy source as its power generation is increased . Here, the redox flow battery, which is a secondary battery having a long service life in addition to the economical efficiency, is attracting attention as a candidate group. Unlike lithium ion batteries, which are commercialized as small batteries, and secondary batteries, which are expected to be applied to next generation secondary batteries, in the case of a redox flow battery, each active material in the positive and negative electrodes And has a capacity expression mechanism that is charged and discharged while undergoing the redox reaction. Thus, when the standard reduction potential of the redox pair of the active material dissolved in the electrolyte solution used as the negative electrolyte solution and the positive electrolyte solution is varied, the potential difference between the cells Is determined.

Also, since the capacity is expressed by the oxidation-reduction reaction of the electrolyte supplied from the external tank, the capacity of the entire cell can be adjusted by adjusting the volume of the external storage tank, thereby facilitating cell design with a desired energy density. In addition to this, the redox reaction of the active redox couples occurs on the surfaces of the anode and cathode, which is advantageous over the conventional ion-based battery. As active materials and solvents for redox flow batteries, vanadium-based salts and aqueous sulfuric acid solutions have been mainly used. However, in the case of mid- to large-sized energy storage systems, it is important that the operating voltage for optimum stack design is not influenced by surrounding environment, that is, temperature, and the improvement of the existing water system is required.

All vanadium-based batteries show some drawbacks because they use water as a solvent. In this case, when the cell is driven thermodynamically at a potential higher than 1.23 V, which is the potential window of water, the electrolyte is lost due to the decomposition of the solvent. In order to prevent the discharge of the electrolyte, I have to go. This is pointed out as a serious problem in terms of the operating voltage. Next, there is a problem that it is difficult to drive at below 0 DEG C due to the thermodynamic characteristics 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 these characteristics, the electrolyte concentration of the entire vanadium redox flow cell based on the aqueous sulfuric acid solution is disadvantageous because the concentration of the solute directly connected to the capacity is inhibited by this precipitation. This problem is pointed out as a major disadvantage in the application of medium to large power storage systems in which high reliability and reliability are important in addition to high capacity and long life.

Organic solvents have been proposed as a solvent for a redox flow cell having an advantage of 1.5 to 2 times as much as an operating voltage in order to improve energy density in comparison with existing water system. In the case of a redox flow cell in which an organic solvent is used as a solvent for the electrolyte solution, the limit of the selection of the redox couple limited by the electrochemical decomposition of water compared with the use of the existing aqueous electrolyte, And there is no disadvantage such as precipitation of vanadium salt at a high temperature, and therefore research is actively conducted. However, according to the study progressed to an existing, in this compared to the conventional water-based systems, the solubility in the oxidation-reduction pair in an organic solvent is significantly lower disadvantages by Wang a paper published in 2013, Advanced Functional . Materials, 23 , 970-986 (0.1M or less), and the difference between the standard reduction potentials of the cathode active material and the anode active material is smaller than or similar to that of the water system, Journal by Sleightholme of power sources , 196 , 5742-5745. Therefore, 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, not only the driving voltage is higher than that of the existing water-based system, but also the solubility of the solute is much higher than that of the existing organic electrolyte, so that the electrolyte has a high energy density as compared with the existing system, .

[Non-Patent Document 1] JOURNAL OF APPLIED ELECTROCHEMISTRY, 20, 463-467 [Non-Patent Document 2] Advanced Functional. Materials, 23, 970-986 [Non-Patent Document 3] Journal of power sources, 196, 5742-5745

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a redox flow battery which is capable of dissolving a larger amount of a solute in a solvent as compared with a known organic electrolyte, A battery having improved energy density of a redox flow battery can be realized and a single organic material can be simultaneously applied to a positive electrode electrolyte solution and a negative electrode electrolyte solution, And it is possible to realize a stable lifetime characteristic without decomposition of the electrolyte even in the continuous oxidation and reduction reaction due to the stable electrochemical reaction of the solute (redox pair), and the metal-ligand compound (metal complexes) Is produced using an organic substance in comparison with an electrolyte solution using It is an object of the present invention to provide an electrolyte for a redox flow battery having a low base cost and a redox flow battery containing the same.

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 includes a redox couple organic compound that is electrochemically and stably reacted , The organic substance is an organic substance including an anode functional group which is oxidized at a basic skeleton containing at least one benzene ring and a cathode functional group which is reduced.

In the electrolyte solution for a redox flow battery according to the present invention, the negative electrode functional group contained in the organic material may be a ketone-based functional group.

In the electrolyte solution for a redox flow battery according to the present invention, the positive electrode functional group contained in the organic material may be an amine-based functional group.

In the electrolytic solution for a redox flow battery according to the present invention, the organic material is NR ₁ R ₂ -Ph-CO-Ph-NR ₃ R ₄ , R ₁ -CO-Ph-NR ₂ -Ph-CO-R ₃ or R ₁ -CO-Ph-NR ₂ R ₃ , wherein R ₁ to R ₄ are each hydrogen, a methyl group, CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, a carboxymethyl group, and an aminocarbonylmethyl group, and Ph is a phenyl group.

In the electrolyte solution for a redox flow battery according to the present invention, the organic substance is a benzene ring in which a hydrogen, a methyl group, an ethyl group, a CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, a carboxylmethyl group, an aminocarbonylmethyl group or a halogen group element Lt; / RTI >

In the electrolytic solution for a redox flow battery according to the present invention, the organic substance may be one in which the positive and negative electrode functional groups have a benzene ring at the center, and the two functional groups are present at the para position and the ortho position of the benzene ring.

In the electrolyte for a redox flow battery according to the present invention, the organic substance is at least one selected from the group consisting of 4,4-bis (diethylamino) benzophenone, [1- (4-dimethylamino) phenyl] ethanone, 4- And [1- (3-dimethylamino) phenyl] ethanone.

In the electrolytic solution for a redox flow battery according to 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 is one or a mixture of two or more kinds selected from sulfuric acid, hydrochloric acid or phosphoric acid. The organic solvent is selected from the group consisting of acetonitrile, dimethyl carbonate, diethyl carbonate, And may be a mixture of one or two or more selected from the group consisting of sodium carbonate, sodium carbonate, sodium carbonate, sodium carbonate, sodium carbonate, potassium carbonate, sodium carbonate,

In the electrolytic solution for a redox flow battery according to the present invention, the organic substance may be dissolved in a mixture of an organic solvent and an aqueous solvent.

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 selected from the group consisting of an alkylammonium salt, a lithium salt and a sodium salt.

In the redox flow battery electrolyte according to the present invention, 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.

In the redox flow battery electrolyte according to the present invention, 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 .

In the redox flow battery electrolyte according to the present invention, 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 the redox flow battery according to the present invention, when the organic matter is dissolved in 0.01 M of the organic matter at a scanning rate of 100 mV s ^-1 and oxidation-reduction reaction is confirmed by the circulating current-voltage method, The difference (E _pa -E _pc ) between the voltages at which the respective peak currents are confirmed may be 1 V or less.

In the electrolytic solution for the redox flow battery according to the present invention, when the organic matter was dissolved in 0.01 M of the organic matter at a scanning rate of 100 mV s ^{-1 and} the redox reaction was confirmed by the cyclic voltammetric method, The difference in the half-wave potential of the reduction reaction may be 1.4 V or more.

In the electrolytic solution for a redox flow battery according to the present invention, when 0.01 M of the organic matter was dissolved in one electrolyte at a scanning rate of 100 mV s ^{-1 and} the redox reaction was confirmed by the circulation current and voltage method, And the half-wave potential of the reduction reaction is 1.4 V or higher, and the metal-ligand can dissolve in the other electrolytic solution.

The electrolyte is used by dissolving two different electrolytes, with the separator interposed therebetween. Therefore, in this case, the dissolved substance means a combination of two different electrolytes.)

In the electrolytic solution for a redox flow battery according to the present invention, the solubility of the organic matter in the electrolytic solution may be 0.1 M to 10 M.

In the redox flow battery according to the present invention, the solubility of the organic material in the electrolytic solution may be 1 M to 10 M.

The redox flow battery according to the present invention is characterized by comprising an electrolyte solution containing the organic material.

In the redox flow battery according to the present invention, the electrolyte containing the organic material may constitute the positive electrode and the negative electrode.

In the redox flow battery according to the present invention, an electrolyte solution containing the organic material may be included as a cathode, and an electrolyte solution containing at least one of a metal-ligand compound and a negative electrode active material may be included as a cathode.

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

In the redox flow battery according to the present invention, the negative electrode may include a negative electrode active material.

In the case of an electrolyte for a redox flow battery prepared by dissolving an electrochemically stable organic compound in an organic solvent according to the present invention, the driving voltage is higher than that of the conventional aqueous system, and the solubility of the active material is higher 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 as compared with conventional systems. In addition, the electrolytic solution for a redox flow battery of the present invention exhibits stable lifetime characteristics without decomposition of the material even when redox reaction is repeated due to stable electrochemical reaction, and also prevents mutual contamination, A battery having characteristics can be designed. In addition, since it is manufactured without using a transition metal species as compared with an electrolyte solution using a metal-ligand type active material, which is already disclosed, it is expected that the manufacturing cost can be lowered.

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.
3 is a graph showing a current-voltage curve by a circulating current-voltage method using the electrolyte of Example 3;
4 is a graph showing a current-voltage curve by a circulating current-voltage method using the electrolyte of Example 4. Fig.
5 is a graph showing a current-voltage curve by a circulating current-voltage method when applied to a positive electrode electrolyte of Example 3;
FIG. 6 is a graph showing a current-voltage curve by a circulating current-voltage method when applied to a negative electrode electrolyte of Example 3. 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 scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the 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 of the present invention is an electrolytic solution for a redox flow battery comprising a solute and a solvent, wherein the solute includes a redox couple organic compound that reacts electrochemically stably, And an anode functional group in which oxidation is carried out in the basic skeleton included therein and a cathode functional group in which reduction is carried out.

The organic material used in the present invention can be used as both a positive electrode active material and a negative electrode active material, and can be used in both positive and negative electrode electrolytes. When one or more electrons move during charging and discharging, There is an advantage in that the complete material can be constituted by a single active material alone.

In the case of the positive electrode active material, it refers to a redox pair which dissolves in both electrolytes and means that the redox couple is charged when the oxidation-reduction pair changes to the higher one of two oxidation states, that is, oxidation occurs. In the case of the negative electrode active material, it refers to a redox couple which dissolves in a negative electrolyte and means that the redox pair is charged to the lower one of the two oxidation states, that is, when it is reduced.

The organic material used in the present invention can be used in both the cathode and the anode electrolyte by the existence of two reactive functional groups, which are the anode functional groups including the anode functional groups in which the basic skeleton containing one or more benzene rings are oxidized and the cathode functional groups in which the reduction is performed Do.

Among the two functional groups, the functional group of the negative electrode is a ketone functional group, which can be used as a functional group of the negative electrode by performing a redox reaction at a low voltage. Since the electrochemical reduction occurs at a considerably low voltage, When combined, a significantly higher operating voltage can be expected. The remaining one functional group is an amine functional group, which can undergo redox reaction at a high voltage and can be used as an anode functional group. The organic material is NR ₁ R ₂ -Ph-CO-Ph-NR ₃ R ₄ , R ₁ -CO-Ph-NR ₂ -Ph-CO-R ₃ or R ₁ -CO-Ph-NR ₂ R ₃ , wherein R ₁ to R ₄ are each hydrogen, a methyl group, CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, a carboxymethyl group, and an aminocarbonylmethyl group, and Ph is a phenyl group.

The organic material used in the present invention may be one in which the benzene ring itself is substituted with hydrogen, a methyl group, an ethyl group, CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, a carboxylmethyl group, an aminocarbonylmethyl group or a halogen group element.

In the organic material used in the present invention, the anode functional group and the cathode functional group have a benzene ring at the center, and the two functional groups may exist at the para position and the ortho position of the benzene ring.

The organic material to be used in the present invention is not particularly limited, and examples thereof include 4,4-bis (diethylamino) benzophenone, [1- (4-dimethylamino) phenyl] ethanone, 4- Dimethylamino) benzophenone and [1- (3-dimethylamino) phenyl] can be used.

In the electrolytic solution for the 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 the solubility of the organic material, the aqueous solvent preferably contains at least one of 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, Amide, propylene carbonate, ethylene carbonate, N-methyl-2-pyrrolidone, fluoroethylene carbonate, ethanol and methanol. Here, a supporting electrolyte is added in order to additionally impart conductivity to the electrolytic solution. In the case of the supporting electrolyte, it is effective that at least one of an alkylammonium salt-based supporting electrolyte, a lithium salt-based supporting electrolyte and a sodium salt- to be.

The supporting electrolyte may be at least one selected from the group consisting of an alkylammonium salt, a lithium salt and a sodium salt.

Alkyl ammonium salt used in the present _{invention, 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 used in the present _{invention, 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 .

Sodium salt used in the present _{invention, 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 .

At least one of the organic materials used in the present invention may be selected and used as a cathode active material or an anode active material. The operating voltage obtained from each combination of oxidation and reduction should be higher than 1.23 V, which is the maximum operating voltage of the water system, desirable.

Therefore, when the reduction maximum potential of the cathode electrolyte is more negative than -2.0 V than the Fc / Fc + (ferrocene / ferrocenium) reference electrode and the maximum oxidation potential of the anode electrolyte is more than 0 V It is preferable that the voltage difference between the oxidation reaction and the reduction reaction between the negative electrode electrolyte dissolved in the solvent and the positive electrode electrolyte dissolved in the solvent is 1.4 V or more. It is also preferable that the difference in voltage at which the peak current thereof is confirmed is lower than 1V. This is because the difference in the voltage causes energy loss during charging and discharging in the actual cell, resulting in lower energy efficiency.

In addition, only one of the organic materials may be used as an electrolyte solution by using only a single active material. In this case, the voltage may be 1.23 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, when the redox reaction is confirmed by the cyclic voltammetry, which is the most typical electrochemical analysis method for confirming this, at a scanning rate of 100 mV s ^-1 at a concentration of 0.01 M , And the difference (E _pa -E _pc ) of the voltage at which the peak current of each of the redox reactions is confirmed is preferably 1 V or less. This is because, in the energy efficiency expressed in a real cell at the difference of this voltage, a small difference of this voltage is preferable for energy efficiency.

In the present invention, when the redox reaction is confirmed at a scanning rate of 100 mV s < ^-1 > by the cyclic voltammetry, (E _pa -E _pc ) of the voltage at which the half-wave potential is confirmed is preferably 1.4 V or more.

In the present invention, when 0.01 M of the organic matter is dissolved in one electrolyte at a scanning rate of 100 mV s ^{-1 and} the redox reaction is confirmed by the circulating current and voltage method, the half wave of each oxidation reaction and the reduction reaction It is preferable that the organic matter having a potential difference of 1.4 V or more is dissolved and the metal-ligand is dissolved in the other electrolytic solution, respectively.

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 M to 10 M. When the concentration of the organic substance dissolved in the electrolyte is more than 0.1 M, it is advantageous in comparison with the conventional organic electrolyte-based system. However, in order to have a higher energy density than the vanadium-based aqueous system, desirable. When the electrolyte solution having an excessively high solubility of more than 10 M is produced, the viscosity of the electrolyte solution is high and the pumping of the electrolyte solution becomes difficult. In the case of the supersaturated solution, Of organic matter may occur.

The redox flow battery according to the present invention is characterized by comprising an electrolyte solution containing the organic material.

In the redox flow battery according to the present invention, the electrolyte containing the organic material may constitute the positive electrode and the negative electrode.

In the redox flow battery according to the present invention, an electrolyte solution containing the organic material may be included as a cathode, and an electrolyte solution containing at least one of a metal-ligand compound and a negative electrode active material may be included as a cathode.

As the metal-ligand compound, it is preferable to use at least one of a metal-acetylacetonate-based material, a metal-biphenyl-based material, and a metal-tetradentate tetradecane based nitrogen ligand-based material.

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

In the redox flow battery according to the present invention, the negative electrode may include a negative electrode active material.

Further, it is characterized in that it includes the above-mentioned solvent.

That is, the present invention is an electrolyte solution for a redox flow cell including a solvent and a solute, wherein the solute includes an organic substance that electrochemically stably reacts, and at least one electron moves during the reaction and is dissolved in the solvent stably The present invention relates to a redox flow cell electrolyte and a redox flow battery using the same.

In one embodiment of the present invention, an organic solvent is dissolved in an organic solvent, and an electrolytic solution. When the redox reaction of the compound proceeds, one or more electrons move, and electrochemical generation of stable radicals , And exist in a stable state in the electrolyte solution. This means that no precipitation occurs in the electrolyte.

Hereinafter, in order to verify the superiority of the electrolytic solution for a redox flow battery of the present invention and the redox flow battery comprising the redox flow battery of the present invention, various experiments were conducted on one embodiment and comparative example of the present invention.

Example  1 to 8 and Comparative Example  1 to 2

Example  1. (4,4- Bis (diethylamino) benzophenone was reacted with  Containing electrolyte)

0.01 mol of 4,4-bis (diethylamino) benzophenone purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetrafluoroborated tetraethyl ammonium to prepare an electrolytic solution.

Example  2. ([1- (4-Dimethylamino) Phenyl ] Ethanone Containing electrolyte)

0.01 mol of [1- (4-dimethylamino) phenylethanone purchased from Sigma-Aldrich Corporation was dissolved in a propylene carbonate solution containing tetraethylboron trifluoride to prepare an electrolytic solution.

Example  3. (4- (Dimethylamino) Benzophenone  Containing electrolyte)

0.01 mol of 4- (dimethylamino) benzophenone purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetrafluoroborated tetraethyl ammonium to prepare an electrolytic solution.

Example  4. ((1- (3-Dimethylamino) Phenyl ] Ethanone  Containing electrolyte)

0.01 mol of [1- (3-dimethylamino) phenylethanone purchased from Sigma-Aldrich Co. was dissolved in a propylene carbonate solution containing tetraethylboron tetrafluoroborate to prepare an electrolytic solution.

Example  5. (4,4- Bis (diethylamino) benzophenone  Solubility experiment)

4,4-bis (diethylamino) benzophenone purchased from Sigma-Aldrich was dissolved in a propylene carbonate solution containing tetrafluoroborated tetramethylammonium tetrafluoroborate as much as possible to prepare an electrolytic solution.

Example  6. ([1- (4-Dimethylamino) Phenylethanone  Solubility experiment)

The electrolyte solution was prepared by dissolving [1- (4-dimethylamino) phenylethanone purchased from Sigma-Aldrich Co. in a propylene carbonate solution containing tetraethylboron tetrafluoroborate as much as possible.

Example  7. (4- (Dimethylamino) Benzophenone  Solubility experiment)

4- (dimethylamino) benzophenone purchased from Sigma-Aldrich was dissolved in a propylene carbonate solution containing tetraethylboron tetrafluoroborate as much as possible to prepare an electrolytic solution.

Example  8. ([1- (3-Dimethylamino) Phenylethanone  Solubility experiment)

The electrolyte solution was prepared by dissolving [1- (3-dimethylamino) phenylethanone purchased from Sigma-Aldrich Co. in a propylene carbonate solution containing tetrafluoroborated tetramethylammonium as much as possible.

Comparative Example  One. ( VOSO ₄ Based electrolytic solution)

A paper published by C. Ponce de Le'on in 2006 Journal of Power Energy densities were calculated based on data extracted from Sources , 160 , 716-32.

Comparative Example  2. ( Thian Torren  Containing electrolyte)

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

Cyclic voltammetry method Cyclic Voltammetry )

[Confirmation of Reaction Voltage of Electrolyte]

Experiments were conducted using the electrolytes obtained in Examples 1 to 3 and the potential scanning speed of 100 mV s ^-1 . Ferrocene was used as an internal reference for precise voltage determination in organic electrolytes. A glacier carbon electrode was used as the working electrode, platinum was used as the counter electrode, and a silver electrode was used as the quasi-reference electrode. Respectively. The electrochemical cell was constructed using these materials and the cyclic voltammetry experiment was carried out. In the case of this experiment, the scan was first performed in the negative voltage direction. In the case of Example 3, the redox reaction was confirmed by first injecting the voltage in the negative direction, and the redox reaction was first confirmed in the positive direction. , It was confirmed whether the actual substances could be oxidized or reduced individually.

[Determination of Reaction Voltage of Active Material]

In Example 1, the reduction reaction was confirmed to be -2.7 V versus the ferrocene, the oxidation reaction was confirmed at about 1.5 V, and the operating voltage of the cell was formed at 4 V. In the case of Example 2, it was confirmed that the reduction reaction to ferrocene was formed at -2.4 V, the oxidation reaction was performed at 0.5 V, and the cell operating voltage was formed at 2.9 V. In the case of Example 3, it was confirmed that the reduction reaction was -2 V with respect to the ferrocene, the oxidation reaction was formed at 0.7 V, and the operating voltage of the cell was formed at 2.7 V. In the case of Example 4, it was confirmed that the reduction reaction was -2.6 V versus the ferrocene, the oxidation reaction was formed at 0.4 V, and the cell operating voltage was formed at 3 V.

[Comparison of Voltage and Energy Density Using Solubility and Half-Wave Potential of Electrolyte]

The half-wave potential, which can be assumed to have a value similar to the maximum solubility of the electrolytes of Examples 1 to 4 and Comparative Example 2 and E ⁰ determined for the electrolytes of Examples 1 to 4 and Comparative Example 2, is shown in Table 1 Respectively. The energy density was compared through the solubility and the driving voltage of the cell predicted from this and Comparative Example 1, respectively. The comparison results of energy density are shown in Table 2 below.

Solubility / M restoration Oxidation Half-wave potential
/ V ( vs. Fc / Fc ⁺ ) Half-wave potential
/ V ( vs. Fc / Fc ⁺ ) Examples 1 and 5 0.2 -2.7 1.3 Examples 2 and 6 One -2.4 0.5 Examples 3 and 7 0.5 -2 0.7 Examples 4 and 8 1.5 -2.6 0.4 Comparative Example 2 0.1 - 0.05

As shown in Table 1, even in the case of an electrolyte prepared by applying the same organic solvent, the organic material according to the present invention has higher solubility and can exhibit a higher capacity when used as an electrolyte of a redox flow cell . In addition, when the electrolytes of Comparative Example 2 and Examples 1 to 4 are compared, in the case of a substance which is generated only by oxidation as in Comparative Example 2, a problem that a cathode electrolyte capable of having a capacity corresponding thereto is used at the same time , It is highly likely to be degraded due to mutual contamination. In the case of Examples 1 to 4, however, it is possible to prevent mutual contamination because it is applied to both the anode and the cathode electrolytic solution by using a single electrolyte solution. The lifetime characteristics of a better battery can be expected.

Combination Solubility / M 1 electron Energy density / Wh L ^-1 Operating Voltage / V Example 1 0.2 4 17.2 Example 2 One 2.9 38.9 Example 3 0.5 2.7 18.1 Example 4 1.5 3 60.3 Comparative Example 1 One 1.26 16.5

As shown in Table 2, compared to Comparative Example 1 through the cells composed of the single organic active material of the present invention, the energy density calculated on the basis of the values reported in the literature of the entire vanadium- Compared with the examples, it can be seen that the energy densities of Examples 1 to 4 are significantly higher than those of Comparative Example 1, which is a pre-aqueous vanadium-based battery. In particular, it can be seen that Embodiment 1 can design a battery having an excellent output characteristic because the voltage is as high as 4V.

As a result of conducting two separate cyclic voltammetric experiments in which the material of Example 3 was used to scan first with a positive voltage and then scan first with a negative voltage, Redox reaction was observed.

Claims (23)

An electrolytic solution for a redox flow battery comprising a solute and a solvent,
Wherein the solute comprises a redox couple organic material that reacts electrochemically stably and wherein the organic material is an organic material comprising an anode functional group where oxidation occurs at a basic skeleton containing at least one benzene ring and a cathode functional group where reduction is performed, Electrolyte for flow cell.
The method according to claim 1,
Wherein the negative electrode functional group contained in the organic material is a ketone-based functional group.
The method according to claim 1,
Wherein the anode functional group contained in the organic material is an amine-based functional group.
The method according to claim 1,
Wherein the organic material is selected from the group consisting of NR ₁ R ₂ -Ph-CO-Ph-NR ₃ R ₄ , _{R 1 -CO-Ph-NR 2} -Ph-CO-R 3 , or R ₁ -CO-Ph-NR ₂ R ₃ of the formula as having a (wherein, Ph is phenyl), wherein in the formula R ₁ to R ₄ is Are each at least one substituent selected from the group consisting of hydrogen, methyl, ethyl, CH ₂ Ph, benzyl, butoxycarbonylmethyl, carboxylmethyl and aminocarbonylmethyl.
The method according to claim 1,
Wherein the organic substance is one in which the benzene ring itself is substituted with hydrogen, a methyl group, an ethyl group, a CH ₂ Ph, a benzyl group, a butoxycarbonylmethyl group, a carboxylmethyl group, an aminocarbonylmethyl group or a halogen group element.
The method according to claim 1,
Wherein the organic material has an anode functional group and a cathode functional group at the center of the benzene ring and the two functional groups are present at the para position and the ortho position of the benzene ring. The method according to claim 1,
Wherein the organic substance is selected from the group consisting of 4,4-bis (diethylamino) benzophenone, [1- (4-dimethylamino) phenyl] ethanone, 4- (dimethylamino) Wherein the electrolytic solution comprises at least one of the following components.
The method according to claim 1,
Wherein the solvent is an aqueous solvent, an organic solvent, or a mixture thereof.
9. The method of claim 8,
The aqueous solvent is one or a mixture of two or more selected from sulfuric acid, hydrochloric acid and phosphoric acid,
Wherein the organic solvent is selected from the group consisting of acetonitrile, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, dimethylformamide, propylene carbonate, ethylene carbonate, N-methyl-2-pyrrolidone, fluoroethylene carbonate, ethanol and methanol An electrolyte for a redox flow cell, which is a mixture of one kind or two or more kinds.
9. The method of claim 8,
Wherein the organic material is dissolved in a mixture of an organic solvent and an aqueous solvent.
The method according to claim 1,
Wherein the electrolytic solution further comprises a supporting electrolyte.
12. The method of claim 11,
Wherein the supporting electrolyte is at least one selected from the group consisting of an alkylammonium salt, a lithium salt and a sodium salt.
13. The method of claim 12,
The alkyl ammonium _{salts, 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 the alkyl cation in the tetraalkylammonium cation is a combination of an ammonium cation selected from the group consisting of methyl, ethyl, butyl and propyl.
13. The method of claim 12,
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. An} electrolytic solution for a redox flow battery, comprising:
13. The method of claim 12,
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. An} electrolytic solution for a redox flow battery, comprising:
The method according to claim 1,
When the organic matter was dissolved in 0.01 M of the organic matter at a scanning rate of 100 mV s ^{-1 and} the redox reaction was confirmed by the cyclic voltammetric method, the voltage at which the peak current of the oxidation reaction and the reduction reaction were confirmed (E _pa -E _pc ) of 1 V or less. The method according to claim 1,
When the organic matter was dissolved in 0.01 M of organic matter at a scanning rate of 100 mV s ^{-1 and} the redox reaction was confirmed by the cyclic voltammetry method, the half-wave potential of each oxidation reaction and the reduction reaction was observed, Of the electrolyte is 1.4 V or more.
The method according to claim 1,
Wherein the solubility of the organic substance in the electrolytic solution is 0.1 M to 10 M , Electrolyte for redox flow battery.
The method according to claim 1,
Wherein the solubility of the organic substance in the electrolyte solution is 1 M to 10 M. 2. The electrolyte solution for a redox flow cell according to claim 1,
A redox flow battery comprising the electrolyte according to any one of claims 1 to 19 as a positive electrode and a negative electrode.
A redox flow battery comprising an electrolyte according to any one of claims 1 to 19 as a positive electrode and an electrolyte solution containing at least one of a metal-ligand compound and a negative electrode active material as a negative electrode.
22. The method of claim 21,
Wherein the negative electrode is an electrolytic solution containing a metal-ligand compound.
22. The method of claim 21,
Wherein the negative electrode is an electrolytic solution containing a negative active material.

Images