High-voltage salt-cavern aqueous organic flow battery and preparation method thereof

Abstract

The invention discloses a high-voltage salt-cavern aqueous organic flow battery and a preparation method thereof, and belongs to the technical field of flow battery electrolyte. A steric hindrance group is introduced into N ortho-position of viologen compound pyridine, or a conjugated group is grafted to para-position of viologen compound pyridine, so that conjugate expansion is realized, and negative electrode organic active molecules with low oxidation-reduction potential and high stability are obtained; and meanwhile, a quaternary ammonium group is directly grafted at a substitution position of the cyclic nitroxide free radical molecule, so that a positive organic active molecule with high oxidation-reduction potential and good stability is prepared. The positive and negative electrode molecules are respectively dissolved in a natural salt-cavern solution rich in multiple salt ions to form an electrolyte, and the high-voltage salt-cavern aqueous organic flow battery is prepared. The system has high voltage, high energy efficiency and good cycle stability, and provides a new design thought and implementation path for constructing an aqueous flow battery system which is high in performance, low in cost and suitable for large-scale energy storage.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a high-voltage salt cavern aqueous organic liquid flow battery and a preparation method thereof. Background Art

[0002] Aqueous organic flow batteries use water-soluble organic redox molecules as energy storage media. They have the advantages of independent energy and power design, rapid charge and discharge response, flexible and scalable systems, and a wide range of raw material sources. They are one of the most promising large-scale energy storage technologies. Salt caverns are natural underground cavities formed after salt mining. They have the characteristics of large volume, good sealing, and mild reaction conditions of the neutral salt solutions they contain. They have been widely used in oil and gas storage. Constructing a flow battery energy storage system based on the actual environment of salt caverns can provide an ideal place for large-scale storage of electrolytes and has significant application potential. However, research in this direction is still in its early stages, and related basic research and engineering exploration are still relatively limited. In-depth systematic research is urgently needed.

[0003] In neutral aqueous organic flow battery systems, viologen derivatives and cyclic nitroxide radical derivatives are widely used as ideal negative and positive active materials due to their excellent redox reversibility, fast electrochemical kinetics and good scalable synthesis characteristics. The basic redox mechanism is: during charging, the oxidized viologen V 2 + accepts 1 electron and transforms into a single electron reduced state V + , and the reduced nitrogen oxide free radical at the positive electrode loses one electron and turns into an oxidized state + N=O; the discharge process is the opposite. It is worth noting that the single electron reduced state of viologen V· + Under certain conditions, it can further accept an electron and transform into a two-electron reduced state V 0 , which provides the possibility of realizing multi-electron transfer reactions and further improving the energy density of the battery.

[0004]

[0005]

[0006] However, the combined application of viologens and cyclic nitrogen oxide free radical molecules generally has the problem of low open-circuit voltage of the battery (usually below 1.5V), which limits the improvement of the energy density of the system. More importantly, in most cases, this type of system can only achieve single electron transfer, making it difficult to fully tap the energy storage potential of the electrolyte molecules. Especially at the negative electrode, the two-electron reduced state structure generated by viologens during the charging process often has poor solubility or stability, and is prone to precipitation or decomposition, resulting in performance degradation problems such as reduced energy and power density and insufficient cycle stability. In addition, in the construction of large-scale energy storage systems, there are also practical challenges such as large area occupied by supporting facilities such as liquid storage tanks and thermal management systems, and high construction and operation and maintenance costs, which further restrict the engineering application and economic development of high-voltage salt cavern batteries. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a high-voltage salt cavern aqueous organic liquid flow battery and a preparation method thereof, so as to solve the problems in the prior art of low open circuit voltage and low energy density of the liquid flow battery when viologen and cyclic nitroxide free radical compounds are used in aqueous organic liquid flow batteries.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A high-voltage salt cavern aqueous organic liquid flow battery, comprising a positive electrode storage tank, a negative electrode storage tank, and a battery stack, wherein the positive electrode storage tank and the negative electrode storage tank are both connected to the battery stack; the positive electrode storage tank stores a positive electrode electrolyte, and the negative electrode storage tank stores a negative electrode electrolyte;

[0010] The positive electrode electrolyte includes a supporting electrolyte and positive electrode organic active molecules, and the negative electrode electrolyte includes a supporting electrolyte and negative electrode organic active molecules;

[0011] The supporting electrolyte is a salt cave solution;

[0012] The negative electrode organic active molecule is a viologen compound with the structural formula:

[0013]

[0014] Wherein, X is a conjugated structure, R1 and R2 are either phosphate or sulfonate, and at least one of the four positions 2, 2', 6, and 6' on the pyridine ring is connected to a methyl group;

[0015] The positive electrode organic active molecule is a cyclic nitrogen oxide free radical compound with the structural formula:

[0016]

[0017] Wherein, the substituents R1, R2, and R3 are any one of the same or different alkyl groups, alkyl sulfate groups, alkyl quaternary ammonium salt groups, or alkyl phosphate groups, and n=0 or 1.

[0018] A further improvement of the present invention is:

[0019] Preferably, X is any one of a benzene ring, pyrazine or bipyridine.

[0020] Preferably, the structural formula of the viologen compound is:

[0021]

[0022] Preferably, the structural formula of the viologen compound is:

[0023]

[0024] Preferably, the structural formula of the viologen compound is:

[0025]

[0026] Preferably, the concentration of the positive electrode organic active molecules in the supporting electrolyte in the positive electrode electrolyte is 0.05-3 mol / L.

[0027] Preferably, the concentration of the negative electrode organic active molecules in the supporting electrolyte in the negative electrode electrolyte is 0.05-3 mol / L.

[0028] Preferably, the battery stack includes a positive current collector, a positive flow field plate, a positive electrode, an ion separator, a negative electrode, a negative flow field plate and a negative current collector which are arranged in sequence.

[0029] A method for preparing the above-mentioned high-voltage salt cavern aqueous organic liquid flow battery comprises the following steps:

[0030] S1, dissolving the viologen compound in the salt cave solution to obtain the negative electrode electrolyte;

[0031] S2, dissolving the cyclic nitroxide radical compound in the salt cave solution to obtain a positive electrode electrolyte;

[0032] S3, placing the positive electrode electrolyte and the negative electrode electrolyte in the positive electrode storage tank and the negative electrode storage tank respectively, connecting the positive electrode storage tank, the negative electrode storage tank and the battery stack to obtain an aqueous organic liquid flow battery.

[0033] Preferably, in S1, the viologen compound can be a phenyl-bridged viologen molecule, a pyrazine-bridged viologen molecule or a bipyridine-bridged viologen molecule; the phenyl-bridged viologen molecule is synthesized by a Suzuki coupling reaction of 1,4-phenyldiboronic acid and a 4-bromo-pyridine derivative, the pyrazine-bridged viologen molecule is synthesized by a substitution reaction between a 4-bromo-pyridine derivative and pyrazine, and the bipyridine-bridged viologen molecule is synthesized by a substitution reaction between a 4-bromo-pyridine derivative and bipyridine.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention discloses a high-voltage salt cave aqueous organic liquid flow battery, which belongs to the technical field of aqueous liquid flow battery electrolyte material preparation. The present invention selectively introduces a group at the ortho position (2, 2', 6, 6'-four positions) of the pyridine N atom of the viologen compound, and uses the electronic effect and geometric effect of the group to regulate the electronic distribution and spatial configuration of the molecule, thereby destroying the weak interaction force between molecules, effectively inhibiting the π-π dimerization between the viologen compounds, and stabilizing its molecular structure; at the same time, a conjugated group is introduced between the two pyridine rings to expand the conjugated system and enhance the π electron delocalization, thereby obtaining a viologen-type negative electrode organic active molecule with higher stability and more negative redox potential. In addition, by directly connecting a quaternary nitrogen-type substituent group to the substitution position of the cyclic nitroxide free radical molecule, and utilizing the strong electron-withdrawing effect of this type of group, a cyclic nitroxide free radical-type positive electrode organic active molecule with high stability and more positive redox potential is obtained. Based on a more negative viologen-based negative electrode organic active molecule and a more positive cyclic nitroxide radical-based positive electrode organic active molecule, the prepared aqueous organic flow battery has a larger potential difference, resulting in a high-voltage aqueous organic flow battery. This positive and negative electrolyte provides a higher open-circuit voltage window for the aqueous organic flow battery, helping to improve the battery's energy and power density. Furthermore, based on the above design of positive and negative organic active molecules, a high-voltage salt cave aqueous organic flow battery was constructed using a natural salt cave solution with a large storage space and rich in various salt ions as the supporting electrolyte. The high concentration of the salt solution improves the electrolyte conductivity and promotes polarization on the electrode surface. This enhanced polarization increases the overpotential of the electrolysis reaction, thereby suppressing hydrogen evolution on the electrode surface, reducing side reactions in the electrolyte, and stabilizing the structure of the negative electrode active molecule. This high-voltage aqueous organic flow battery electrolyte design based on a salt cave solution achieves the goals of reducing cost, improving quality, and enhancing efficiency, providing a new method and path for the further promotion and application of flow batteries.

[0036] The present invention also discloses a method for preparing a high-voltage salt cavern aqueous organic flow battery. This method comprises grafting groups ortho-positioned on the pyridine nitrogen atom of a viologen compound, performing conjugated extension on the viologen compound, and directly attaching quaternary nitrogen-type substituents to the substitution positions of tetramethylcyclic nitroxide radical molecules to obtain negative and positive electrode active molecules. These molecules are then dissolved in a natural salt cavern solution rich in various salt ions to prepare a high-voltage salt cavern aqueous organic flow battery electrolyte. The viologen compound disclosed in the present invention has a low redox potential and excellent stability, and the tetramethylcyclic nitroxide radical molecule has a high redox potential. The resulting salt cavern aqueous organic flow battery has high voltage and energy efficiency, providing new design ideas and solutions for high-performance, low-cost aqueous organic flow batteries.

[0037] In addition, the present invention uses natural salt cavern solution as the supporting electrolyte solution. Targeting the salt cavern solution environment with a wide variety of ions and high concentration, the salt cavern solution is suitable for the aforementioned positive and negative electrode active molecules while also obtaining negative electrode active molecules suitable for the operating conditions of a flow battery with a salt cavern structure. The negative electrode electrolyte prepared with this negative electrode active molecule provides a wider potential window for aqueous organic flow batteries, providing the battery with greater current density and power. This high-voltage electrolyte design based on salt cavern aqueous organic flow batteries provides a new method and path for the further promotion and application of salt cavern flow batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 1 is a cyclic voltammogram of the flow battery assembled in Example 1 of the present invention.

[0039] Figure 2 1 is a cyclic charge and discharge curve diagram of the flow battery assembled in Example 1 of the present invention.

[0040] Figure 3 1 is a cyclic voltammetry curve of the flow battery assembled in Example 2 of the present invention. DETAILED DESCRIPTION

[0041] The present invention is described in further detail below with reference to the accompanying drawings:

[0042] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0043] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0044] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0045] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0046] The present invention discloses a high-voltage salt cavern aqueous organic liquid flow battery, which includes a positive electrode storage tank, a negative electrode storage tank and a battery stack, wherein the positive electrode storage tank and the negative electrode storage tank are both connected to the battery stack; the positive electrode storage tank stores a positive electrode electrolyte, and the negative electrode storage tank stores a negative electrode electrolyte;

[0047] The negative electrode electrolyte consists of negative electrode organic active molecules and a supporting electrolyte solution. The negative electrode organic active molecules are viologen compounds, the supporting electrolyte solution is a natural salt cave solution, and the concentration of the negative electrode organic active molecules is 0.05-3 mol / L.

[0048] In the embodiment of the present invention, the oxidized structural formula of the viologen compound is:

[0049]

[0050] Among them, the X structure between the pyridine rings in the viologen compounds is a conjugated structure, the groups R1 and R2 are any one of phosphate and sulfonate, and at least one of the four positions 2, 2', 6, and 6' on the pyridine ring in the molecule is connected to a methyl group.

[0051] The positive electrode electrolyte adopts a tetramethyl cyclic nitroxide free radical molecule electrolyte, which includes a positive electrode organic active molecule and a supporting electrolyte solution. The concentration of the positive electrode organic active molecule is 0.05-3 mol / L. The supporting electrolyte solution is a natural salt cave solution. The positive electrode organic active molecule is a cyclic nitroxide free radical molecule, and the structural formula is as follows:

[0052]

[0053] The substituents R3, R4, and R5 can be the same or different and can be any one of alkyl, alkyl sulfate, alkyl quaternary ammonium salt, or alkyl phosphate groups, and n=0 or 1.

[0054] In the embodiment of the present invention, the negative electrode organic active molecule is dissolved in the supporting electrolyte solution. The methyl group and other conjugated groups introduced through molecular structural design effectively regulate the spatial structure and charge distribution of the viologen compound active molecule, reduce the redox potential of the viologen compound active molecule, promote the two-electron reduction process of the viologen compound active molecule in the system, improve the stability of the negative electrode electrolyte, effectively broaden the electrochemical window of the battery, suppress the battery's capacity decay, and significantly improve the battery performance.

[0055] In some embodiments of the present invention, the conjugated structure can be any of a benzene ring, pyrazine, or bipyridine, forming phenyl-bridged viologen molecules, pyrazine-bridged viologen molecules, and bipyridine-bridged viologen molecules. The intermediate conjugated structure can enhance electron delocalization, effectively regulating the redox potential of the molecule and enhancing its stability.

[0056] The structural formula of the phenyl-bridged viologen molecule is:

[0057]

[0058] The structural formula of the pyrazine-bridged viologen molecule is:

[0059]

[0060] The structural formula of the bipyridine-bridged viologen molecule is:

[0061]

[0062] In some embodiments of the present invention, two of the four positions 2, 2', 6, and 6' on the pyridine ring in the molecule are connected to methyl groups, and the structural formula is:

[0063]

[0064] In some embodiments of the present invention, three of the four positions 2, 2', 6, and 6' on the pyridine ring in the molecule are connected to methyl groups, and the structural formula is:

[0065]

[0066] In some embodiments of the present invention, four of the four positions 2, 2', 6, and 6' on the pyridine ring in the molecule are connected to methyl groups, and the structural formula is:

[0067]

[0068] In the above structure, as more methyl groups are introduced on the pyridine ring, the potential of the entire negative electrode organic active molecule becomes lower, further increasing the pressure difference with the positive electrode electrolyte. At the same time, it can enhance steric hindrance and block the space for molecular aggregation. However, the solubility in the entire salt cave solution is reduced. Therefore, the specific number of methyl connections needs to be adjusted according to actual conditions.

[0069] For example, the alkyl group in the present invention can be methyl, ethyl, propyl, butyl, pentyl, etc.

[0070] In some embodiments of the present invention, the positive electrode organic electrolyte molecule uses alkyl sulfate as a substituent, 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical, the structure of which is shown below:

[0071]

[0072] The supporting electrolyte solution is a natural salt cave solution, the main component of which is a saturated salt solution formed by various halides, which is usually rich in various metal ions such as K + 、Na + Mg 2+ etc. The composition of the solution depends on the genesis and geological conditions of the salt cavern.

[0073] The high-voltage salt cavern aqueous organic liquid flow battery disclosed in the present invention comprises a battery stack comprising a positive flow field plate, a positive electrode, an ion separator, a negative electrode, a negative flow field plate and a current collector.

[0074] Specifically, the aqueous organic liquid flow battery uses a copper plate as a current collector, a graphite plate as a flow field plate, and a carbon felt as a reaction electrode, and the positive electrode and the negative electrode are separated by a cationic diaphragm.

[0075] The present invention discloses a method for preparing a high-voltage aqueous organic flow battery, comprising the following steps:

[0076] S1. First, synthesize the required viologen compounds. Phenyl-bridged viologen molecules are synthesized via a Suzuki coupling reaction between 1,4-phenylenediboronic acid and a 4-bromo-pyridine derivative. Pyrazine-bridged viologen molecules are synthesized via a substitution reaction between a 4-bromo-pyridine derivative and pyrazine. Bipyridine-bridged viologen molecules are synthesized via a substitution reaction between a 4-bromo-pyridine derivative and bipyridine. Next, weigh the viologen compound as the negative electrode organic active molecule and dissolve it in the salt cave solution to obtain the negative electrode electrolyte.

[0077] S2, dissolving the cyclic nitroxide free radical molecular compound in the salt cave solution to obtain a positive electrode electrolyte;

[0078] S3, placing the positive electrode electrolyte and the negative electrode electrolyte in the positive electrode storage tank and the negative electrode storage tank respectively, connecting the positive electrode storage tank, the negative electrode storage tank and the battery stack to obtain an aqueous organic liquid flow battery.

[0079] During the mixing process, the supporting electrolyte solution is mixed and sonicated to fully dissolve the active material in the supporting electrolyte. The entire preparation process is simple, efficient, and easy to implement. This innovative preparation strategy significantly enhances the stability and ionic conductivity of the negative electrode electrolyte, significantly improving the battery's capacity retention, and providing a solid foundation for the long-term use and performance optimization of aqueous organic flow batteries.

[0080] The following is further described with reference to specific embodiments.

[0081] Example 1

[0082] 1) Synthesis of 3,3'-[1,4-phenylbis(2,6-dimethylpyridin-1-ium-4,1-diyl)]bis(propane-1-sulfonate).

[0083] To a 250 mL single-necked round-bottom flask, 4-bromo-2,6-dimethylpyridine (4.71 g, 25 mmol), 1,4-phenylenediboronic acid (2 g, 12 mmol), tetrakis(triphenylphosphine)palladium (0.7 g, 0.06 mmol), and potassium carbonate (10 g, 72.3 mmol) were added. 100 mL of a mixed solvent of toluene, water, and ethanol (volume ratio of 4:1:1) was then added. The resulting mixture was stirred at 100°C under a nitrogen atmosphere for 72 hours, and the solution eventually turned brownish yellow. After the reaction mixture cooled to room temperature, the solvent was removed by distillation under reduced pressure. Deionized water and dichloromethane were added to the resulting mixture, and the mixture was extracted three times, and the organic phase was collected. A small amount of concentrated hydrochloric acid solution was slowly added dropwise to the above organic phase to adjust the pH of the organic phase to 2.3, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was rinsed three times with dichloromethane, and the filter cake was collected to obtain a white solid powder, which is the hydrochloride of the target compound; the obtained white solid powder was dissolved in a small amount of deionized water, and sodium bicarbonate was slowly added while stirring, and the pH of the mixed solution was adjusted to 8-9, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was washed three times with deionized water, the filter cake was collected, and vacuum dried at 50°C for 24 hours to obtain a white needle-shaped solid powder.

[0084] To a 100 mL single-necked round-bottom flask was added the white needle-shaped solid powder obtained above (1 g, 3.5 mmol), 1,3-propane sultone (1.058 g, 8.6 mmol), and 20 mL of DMF solution. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a yellow-brown solid powder, the target compound, in a yield of approximately 75%.

[0085]

[0086] 2) Dissolve the above product in 10 mL of 1 mol / L potassium chloride aqueous solution and stir until a uniform solution is formed with a concentration of 0.002 mol / L. The mixed solution prepared above is subjected to cyclic voltammetry using a three-electrode system, wherein silver / silver chloride is used as the reference electrode, a platinum electrode is used as the counter electrode, and a glassy carbon electrode is used as the working electrode at a scan rate of 100 mV / s. The cyclic voltammetry scan results are shown in FIG. Figure 1 (Left) shown.

[0087] The preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical was dissolved in 10 mL of 1 mol / L potassium chloride aqueous solution and stirred until a uniform solution was formed with a concentration of 0.05 mol / L. The prepared mixed solution was subjected to cyclic voltammetry using a three-electrode system, wherein silver / silver chloride was used as the reference electrode, a platinum electrode was used as the counter electrode, and a glassy carbon electrode was used as the working electrode at a scan rate of 100 mV / s. The cyclic voltammetry scan results are shown in FIG. Figure 1 (right) shown.

[0088] Depend on Figure 1 The data show that both the bipyridine compound and the tetramethylcyclic carbonyl radical compound exhibit a pair of distinct, reversible redox peaks in neutral aqueous solution, demonstrating good electrochemical reversibility. Furthermore, using Ag / AgCl as a reference electrode, the bipyridine compound exhibits a relatively negative redox potential at an average of -1.1 V, while the tetramethylcyclic nitrogen radical compound exhibits a relatively positive redox potential at a average of 0.902 V, confirming the wide electrochemical window of aqueous organic flow batteries using these two active materials as the negative and positive electrodes.

[0089] 3) Flow battery testing

[0090] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred cyclic nitrogen oxide free radical compound and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak it for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0091] The battery was tested for performance by charging it at a constant current of 200mA, maintaining constant voltage charging after reaching 1.2V, and stopping charging when the current was less than 5mA; then discharging it at a constant current of 200mA, maintaining constant voltage discharge after reaching 0.65V, and stopping charging when the current was less than 5mA. The charge and discharge cycle test was carried out according to this system. Figure 2 The obtained battery can work normally. In the charge and discharge cycle test of more than 100 cycles, the coulomb efficiency of the installed battery is close to 100%, the energy efficiency is 87%, and the battery discharge capacity is stable, indicating that the battery has stable cycle and long life, confirming the feasibility of applying the positive and negative active molecules used in the present invention in salt cave solutions.

[0092] Example 2

[0093] 1) Synthesis of {1,4-phenylbis[2,6-dimethylpyridin-1-ium-4,1-diylbis(propane-3,1-diyl)]}bis(phosphonate)

[0094] To a 250 mL single-necked round-bottom flask, 4-bromo-2,6-dimethylpyridine (4.71 g, 25 mmol), 1,4-phenylenediboronic acid (2 g, 12 mmol), tetrakis(triphenylphosphine)palladium (0.7 g, 0.06 mmol), and potassium carbonate (10 g, 72.3 mmol) were added, along with 100 mL of a 4:1:1 volume ratio of toluene, water, and ethanol. The resulting mixture was stirred at 100°C under a nitrogen atmosphere for 72 hours, resulting in a brownish-yellow solution. After the reaction mixture cooled to room temperature, the solvent was removed by vacuum distillation. Deionized water and dichloromethane were added to the resulting mixture, and the mixture was extracted three times. The organic phase was collected. A small amount of concentrated hydrochloric acid solution was slowly added dropwise to the above organic phase to adjust the pH of the mixture to 2.3, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was rinsed three times with dichloromethane, and the filter cake was collected to obtain a white solid powder, which is the hydrochloride of the target compound; the obtained white solid powder was dissolved in a small amount of deionized water, and sodium bicarbonate was slowly added while stirring, and the pH of the mixed solution was adjusted to 8-9, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was washed three times with deionized water, the filter cake was collected, and vacuum dried at 50°C for 24 hours to obtain a white needle-shaped solid powder.

[0095] The white needle-shaped solid powder (5.7 g, 20 mmol), diethyl (3-bromopropyl)phosphonate (12.95 g, 50 mmol), and 200 mL of anhydrous acetonitrile solvent were added to a 500 mL round-bottom flask equipped with a magnetic stirrer, and the system was refluxed at 100° C. overnight. After the reaction was completed, the reaction was naturally cooled to room temperature, the formed solid was filtered, and the product was washed with anhydrous acetonitrile or anhydrous ether. The solid product was collected and dried in a forced air drying oven at 60° C. overnight to obtain a white solid (8.9 g, yield ~85%).

[0096] A 100 mL Shrek reaction flask equipped with a magnetic stirrer was added with the white solid (2.6 g, 5 mmol) obtained in the previous step, trimethylsilyl bromide (7.65 g, 50 mmol) and 60 mL of chloroform solvent. Under nitrogen, the reaction system was refluxed at 100 ° C overnight. After the reaction, the reaction system was naturally cooled to room temperature. The solution was then transferred from the Shrek reaction flask to a beaker. Excess isopropanol (~10 mL) was slowly added to the beaker to quench the reaction. At this time, a small amount of white smoke was emitted. 50 mL of ethyl acetate was then added to the beaker to disperse the precipitate. Finally, the formed solid was filtered and the product was washed with isopropanol (3×50 mL) and acetone (2×30 mL). It was then dried in a forced air drying oven at 60 ° C overnight to obtain a white solid. The obtained solid was dissolved in water, and the bromide ions of the obtained compound were converted into chloride ions using a chloride ion exchange resin. After drying, a yellow solid powder was obtained, which was the final target product (2.52 g, yield ~95%).

[0097]

[0098] 2) Dissolve the above product in 10 mL of 1 mol / L potassium chloride aqueous solution and stir until a uniform solution is formed with a concentration of 0.002 mol / L. The mixed solution prepared above is subjected to cyclic voltammetry using a three-electrode system, wherein silver / silver chloride is used as the reference electrode, a platinum electrode is used as the counter electrode, and a glassy carbon electrode is used as the working electrode at a scan rate of 100 mV / s. The cyclic voltammetry scan results are shown in FIG. Figure 3 shown.

[0099] Depend on Figure 3 The data show that the bipyridine compound exhibits a pair of distinct, reversible redox peaks in neutral aqueous solution, demonstrating good electrochemical reversibility. Furthermore, using a saturated Ag / AgCl electrode as a reference electrode, the bipyridine compound exhibits an average potential of -0.99 V, demonstrating a relatively negative redox potential as a negative electrode material, which helps broaden the potential window of the system.

[0100] 3) Flow battery testing

[0101] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0102] Example 3

[0103] 1) Synthesis of 3,3'-[1,4-phenylbis(2-methylpyridin-1-ium-4,1-diyl)]bis(propane-1-sulfonate)

[0104] To a 250 mL single-necked round-bottom flask, 4-bromo-2-methylpyridine (4.3 g, 25 mmol), 1,4-phenylenediboronic acid (2 g, 12 mmol), tetrakis(triphenylphosphine)palladium (0.7 g, 0.06 mmol), and potassium carbonate (10 g, 72.3 mmol) were added, followed by 100 mL of a mixed solvent of toluene, water, and ethanol (4:1:1 volume ratio). The resulting mixture was stirred at 100°C under a nitrogen atmosphere for 72 hours, and the solution eventually turned brownish yellow. After the reaction mixture cooled to room temperature, the solvent was removed by distillation under reduced pressure. Deionized water and dichloromethane were added to the resulting mixture, and the mixture was extracted three times, and the organic phase was collected. A small amount of concentrated hydrochloric acid solution was slowly added dropwise to the above organic phase to adjust the pH of the mixture to 2.3, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was rinsed three times with dichloromethane, and the filter cake was collected to obtain a white solid powder, which is the hydrochloride of the target compound; the obtained white solid powder was dissolved in a small amount of deionized water, and sodium bicarbonate was slowly added while stirring, and the pH of the mixed solution was adjusted to 8-9, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was washed three times with deionized water, the filter cake was collected, and vacuum dried at 50°C for 24 hours to obtain a white needle-shaped solid powder.

[0105] To a 100 mL single-necked round-bottom flask, the white needle-shaped solid powder obtained above (0.92 g, 3.5 mmol), 1,3-propane sultone (1.058 g, 8.6 mmol), and 20 mL of DMF solution were added. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a yellow-brown solid powder, the target compound, in a yield of approximately 75%.

[0106]

[0107] 2) Flow battery testing

[0108] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0109] Example 4

[0110] 1) Synthesis of 3-{4-[4-(2,6-dimethyl-1-(3-sulfonylpropyl)pyridin-1-ium-4-yl]phenyl}-2-methylpyridin-1-yl)propane-1-sulfonate

[0111] To a 250 mL single-necked round-bottom flask, 4-bromo-2,6-dimethylpyridine (2.36 g, 12.5 mmol), 4-bromo-2-methylpyridine (2.15 g, 12.5 mmol), 1,4-phenylenediboronic acid (2 g, 12 mmol), tetrakis(triphenylphosphine)palladium (0.7 g, 0.06 mmol), and potassium carbonate (10 g, 72.3 mmol) were added. A 100 mL mixture of toluene, water, and ethanol (4:1:1 volume ratio) was then added. The resulting mixture was stirred at 100°C under a nitrogen atmosphere for 72 hours, resulting in a brownish-yellow solution. After the reaction mixture cooled to room temperature, the solvent was removed by distillation under reduced pressure. Deionized water and dichloromethane were added to the resulting mixture, and the mixture was extracted three times. The organic phase was collected. A small amount of concentrated hydrochloric acid solution was slowly added dropwise to the above organic phase to adjust the pH of the mixture to 2.3, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was rinsed three times with dichloromethane, and the filter cake was collected to obtain a white solid powder, which is the hydrochloride of the target compound; the obtained white solid powder was dissolved in a small amount of deionized water, and sodium bicarbonate was slowly added while stirring, and the pH of the mixed solution was adjusted to 8-9, and stirring was continued for 30 minutes, accompanied by the precipitation of a large amount of white solid; the obtained reaction mixture was filtered, the filter cake was washed three times with deionized water, the filter cake was collected, and vacuum dried at 50°C for 24 hours to obtain a white needle-shaped solid powder.

[0112] To a 100 mL single-necked round-bottom flask, the obtained white needle-shaped solid powder (1 g, 3.5 mmol), 1,3-propane sultone (1.058 g, 8.6 mmol), and 20 mL of DMF solution were added. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a yellow-brown solid powder, the target compound, in a yield of approximately 75%.

[0113]

[0114] 2) Flow battery testing

[0115] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0116] Example 5

[0117] 1) Synthesis of 3,3'-[pyrazine-1,4-diammonium-1,4-diylbis(2,6-dimethylpyridin-1-ium-4,1-diyl)]bis(propane-1-sulfonate)

[0118] To a 250 mL single-necked round-bottom flask, 4-bromo-2,6-dimethylpyridine (4.71 g, 25 mmol) and pyrazine (0.96 g, 12 mmol) were added, along with 50 mL of DMF solution. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours, resulting in the precipitation of a large amount of purple-black solid. The resulting reaction mixture was filtered, and the filter cake was washed three times with acetone. The filter cake was collected and vacuum-dried at 50°C for 24 hours to obtain a purple-black solid powder.

[0119] To a 100 mL single-necked round-bottom flask, the purple-black solid powder (1 g, 2.2 mmol), 1,3-propane sultone (0.59 g, 4.8 mmol), and 20 mL of DMF solution were added. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a dark brown solid powder, the target compound, in a yield of approximately 75%.

[0120]

[0121] 2) Flow battery testing

[0122] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0123] The battery was tested for performance by charging it at a constant current of 200mA, maintaining constant voltage charging after reaching 1.2V, and stopping charging when the current was less than 5mA; then discharging it at a constant current of 200mA, maintaining constant voltage discharge after reaching 0.65V, and stopping charging when the current was less than 5mA. The charge and discharge cycle test was carried out according to this system. Figure 3 The available battery can work normally. In the charge and discharge cycle test of more than 1900 cycles, the coulomb efficiency of the installed battery is close to 100%, the energy efficiency is 87%, and the battery discharge capacity is stable, indicating that the battery has stable cycle and long life.

[0124] Example 6

[0125] 1) Synthesis of 3,3'-(2,2"',6,6"'-tetramethyl-[4,1':4',4":1",4"'-tetrapyridine]-1,1',1",1"-tetraammonium-1,1"-diyl)bis(propane-1-sulfonate)

[0126] To a 250 mL single-necked round-bottom flask, 4-bromo-2,6-dimethylpyridine (4.71 g, 25 mmol) and 4,4'-bipyridine (1.87 g, 12 mmol) were added, along with 50 mL of DMF solution. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours, resulting in the precipitation of a large amount of purple-black solid. The resulting reaction mixture was filtered, and the filter cake was washed three times with acetone. The filter cake was collected and vacuum-dried at 50°C for 24 hours to yield a purple-black solid powder.

[0127] To a 100 mL single-necked round-bottom flask, the purple-black solid powder (1 g, 1.7 mmol), 1,3-propane sultone (0.46 g, 3.7 mmol), and 20 mL of DMF solution were added. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a dark brown solid powder, the target compound, in a yield of approximately 75%.

[0128]

[0129] 2) Flow battery testing

[0130] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0131] Example 7

[0132] 1) Synthesis of 3,3'-[pyrazine-1,4-diammonium-1,4-diylbis(2-methylpyridin-1-ium-4,1-diyl)]bis(propane-1-sulfonate)

[0133] To a 250 mL single-necked round-bottom flask, 4-bromo-2-methylpyridine (4.30 g, 25 mmol) and pyrazine (0.96 g, 12 mmol) were added, along with 50 mL of DMF solution. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours, with the precipitation of a large amount of purple-black solid. The resulting reaction mixture was filtered, and the filter cake was washed three times with acetone. The filter cake was collected and vacuum-dried at 50°C for 24 hours to obtain a purple-black solid powder.

[0134] To a 100 mL single-necked round-bottom flask, the purple-black solid powder (1 g, 2.4 mmol), 1,3-propane sultone (0.65 g, 5.3 mmol), and 20 mL of DMF solution were added. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a dark brown solid powder, the target compound, in a yield of approximately 75%.

[0135]

[0136] 2) Flow battery testing

[0137] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0138] Example 8

[0139] 1) Synthesis of 3,3'-(2,2"'-dimethyl-[4,1':4',4":1",4"'-tetrapyridine]-1,1',1",1"-tetraammonium-1,1"-diyl)bis(propane-1-sulfonate)

[0140] To a 250 mL single-necked round-bottom flask, 4-bromo-2-methylpyridine (4.30 g, 25 mmol) and 4,4'-bipyridine (1.87 g, 12 mmol) were added, along with 50 mL of DMF solution. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours, resulting in the precipitation of a large amount of purple-black solid. The resulting reaction mixture was filtered, and the filter cake was washed three times with acetone. The filter cake was collected and vacuum-dried at 50°C for 24 hours to yield a purple-black solid powder.

[0141] To a 100 mL single-necked round-bottom flask, the purple-black solid powder (1 g, 2 mmol), 1,3-propane sultone (0.54 g, 4.4 mmol), and 20 mL of DMF solution were added. The resulting mixture was stirred at 155°C under a nitrogen atmosphere for 12 hours. After the reaction mixture cooled to room temperature, it was filtered, and the filter cake was rinsed three times with isopropanol. The filter cake was collected and dried under vacuum at 50°C for 24 hours to obtain a dark brown solid powder, the target compound, in a yield of approximately 75%.

[0142]

[0143] 2) Flow battery testing

[0144] Weigh the product of step 1) and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.05mol / L electrolyte solution, take 8mL as the negative electrode, weigh the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidin-1-oxyl free radical molecule and dissolve it in the salt cave solution, stir to form a uniform solution, prepare a 0.1mol / L electrolyte solution, and take 12mL as the positive electrode. Take commercial graphite felt and put it into 1mol / L sulfuric acid solution, stir and soak for 10 hours, take it out and wash it with deionized water for later use. Assemble the battery in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and drive the liquid with a peristaltic pump.

[0145] Example 9

[0146] In this embodiment, the product of step 1) in Example 1 is weighed and dissolved in a salt cave solution, stirred to form a uniform solution, and a 0.5 mol / L electrolyte solution is prepared. 8 mL is taken as the negative electrode, and the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidine-1-oxyl free radical molecule is weighed and dissolved in a salt cave solution, stirred to form a uniform solution, and a 0.5 mol / L electrolyte solution is prepared. 12 mL is taken as the positive electrode. Commercial graphite felt is placed in a 1 mol / L sulfuric acid solution, stirred and soaked for 10 hours, taken out and washed with deionized water for standby use. The battery is assembled in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and the liquid is driven by a peristaltic pump.

[0147] Example 10

[0148] In this embodiment, the product of step 1) in Example 1 is weighed and dissolved in a salt cave solution, stirred to form a uniform solution, and a 1mol / L electrolyte solution is prepared. 8mL is taken as the negative electrode, and the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidine-1-oxyl free radical molecule is weighed and dissolved in a salt cave solution, stirred to form a uniform solution, and a 1mol / L electrolyte solution is prepared. 12mL is taken as the positive electrode. Commercial graphite felt is placed in a 1mol / L sulfuric acid solution, stirred and soaked for 10 hours, taken out and washed with deionized water for standby use. The battery is assembled in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and the liquid is driven by a peristaltic pump.

[0149] Example 11

[0150] In this embodiment, the product of step 1) in Example 1 is weighed and dissolved in a salt cave solution, stirred to form a uniform solution, and a 3mol / L electrolyte solution is prepared. 8mL is taken as the negative electrode, and the preferred 4-[3-(dimethylamino)propanesulfonic acid]-2,2,6,6-tetramethylpiperidine-1-oxyl free radical molecule is weighed and dissolved in a salt cave solution, stirred to form a uniform solution, and a 3mol / L electrolyte solution is prepared. 12mL is taken as the positive electrode. Commercial graphite felt is placed in a 1mol / L sulfuric acid solution, stirred and soaked for 10 hours, taken out and washed with deionized water for standby use. The battery is assembled in the order and position of copper current collector-graphite plate flow channel-graphite felt-ion exchange membrane-graphite felt-graphite plate flow channel-copper current collector, and the liquid is driven by a peristaltic pump.

[0151] 2. Structural Identification

[0152] The physical properties and structures of the negative electrode active molecules synthesized in Examples 1-8 of the present invention were analyzed, and the specific hydrogen spectrum data are as follows:

[0153] Negative electrode active molecules synthesized in Example 1: 1 H NMR (500MHz, Chloroform-d) δ7.86 (s, 1H), 7.68 (s, 1H), 4.65 (t, J=7.5Hz, 1H), 2.80 (t, J=11.4Hz, 1H), 2.67 (s, 3H), 2.28 (tt, J=11.3, 7.5Hz, 1H).

[0154] Negative electrode active molecules synthesized in Example 2: 1H NMR (500MHz, Chloroform-d) δ7.86 (s, 1H), 7.68 (s, 1H), 4.63 (t, J = 6.9Hz, 1H), 2.67 (s, 3H), 2.34-2.24 (m, 1H), 2.24-2.07 (m, 1H).

[0155] The negative electrode active molecules synthesized in Example 3: 1 H NMR (500MHz, Chloroform-d) δ8.68 (d, J=7.1Hz, 1H), 8.43 (d, J=1.9Hz, 1H), 8.32 (dd, J=7.2, 2.1Hz, 1H) , 7.64 (s, 2H), 4.70 (t, J=7.4Hz, 2H), 2.82 (t, J=11.4Hz, 2H), 2.69 (s, 3H), 2.26 (tt, J=11.3, 7.3Hz, 2H).

[0156] Negative electrode active molecules synthesized in Example 4: 1 H NMR (500MHz, Chloroform-d) δ8.68 (d, J=7.1Hz, 1H), 8.45-8.41 (m, 1H), 8.32 (dd, J=7.2, 1.9Hz, 1H), 7.86 (s, 2H), 7 .71-7.61 (m, 4H), 4.68 (dt, J=23.2, 7.5Hz, 3H), 2.81 (q, J=11.3Hz, 3H), 2.68 (d, J=11.7Hz, 7H), 2.34-2.21 (m, 4H).

[0157] Negative electrode active molecules synthesized in Example 5: 1 H NMR (500MHz, Chloroform-d) δ9.66 (s, 1H), 7.97 (s, 1H), 4.67 (t, J=7.5Hz, 1H), 2.80 (t, J=11.4Hz, 1H), 2.72 (s, 3H), 2.28 (tt, J=11.4, 7.6Hz, 1H).

[0158] Negative electrode active molecules synthesized in Example 6: 1 H NMR (500MHz, Chloroform-d) δ9.43-9.37 (m, 1H), 9.05-8.99 (m, 1H), 8.10 (s, 1H), 4.6 7 (t, J=7.5Hz, 1H), 2.80 (t, J=11.4Hz, 1H), 2.72 (s, 3H), 2.28 (tt, J=11.4, 7.6Hz, 1H).

[0159] Negative electrode active molecules synthesized in Example 7: 1 H NMR (500MHz, Chloroform-d) δ9.73 (s, 2H), 8.81-8.76 (m, 1H), 8.12-8.07 (m, 3H) , 4.68 (t, J=7.4Hz, 2H), 2.82 (t, J=11.4Hz, 2H), 2.76 (s, 3H), 2.32-2.21 (m, 2H).

[0160] Negative electrode active molecules synthesized in Example 8: 1 H NMR (500MHz, Chloroform-d) δ9.42-9.37 (m, 3H), 9.07-9.01 (m, 3H), 8.87 (d, J=7.6Hz, 1H), 8.29 (dd, J=7.7, 2. 0Hz, 1H), 8.09 (d, J=2.3Hz, 1H), 4.68 (t, J=7.4Hz, 2H), 2.82 (t, J=11.4Hz, 2H), 2.76 (s, 3H), 2.32-2.21 (m, 2H).

[0161] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high voltage salt cavern aqueous organic flow battery, characterized in that: The battery comprises a positive electrode liquid storage tank, a negative electrode liquid storage tank and a battery stack, wherein the positive electrode liquid storage tank and the negative electrode liquid storage tank are both connected to the battery stack; the positive electrode liquid storage tank stores positive electrode electrolyte, and the negative electrode liquid storage tank stores negative electrode electrolyte; The positive electrode electrolyte includes a supporting electrolyte and positive electrode organic active molecules, and the negative electrode electrolyte includes a supporting electrolyte and negative electrode organic active molecules; The supporting electrolyte is a salt cave solution; The negative electrode organic active molecule is a viologen compound with the structural formula: Wherein, X is a conjugated structure, R1 and R2 are either phosphate or sulfonate, and at least one of the four positions 2, 2', 6, and 6' on the pyridine ring is connected to a methyl group; The positive electrode organic active molecule is a cyclic nitrogen oxide free radical compound with the structural formula: Wherein, the substituents R1, R2, and R3 are any one of the same or different alkyl groups, alkyl sulfate groups, alkyl quaternary ammonium salt groups, or alkyl phosphate groups, and n=0 or 1.

2. A high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The X is any one of a benzene ring, pyrazine or bipyridine.

3. The high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The structural formula of the viologen compound is:

4. The high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The structural formula of the viologen compound is:

5. The high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The structural formula of the viologen compound is:

6. The high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The concentration of the positive electrode organic active molecules in the supporting electrolyte in the positive electrode electrolyte is 0.05-3 mol / L.

7. The high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The concentration of the negative electrode organic active molecules in the supporting electrolyte in the negative electrode electrolyte is 0.05-3 mol / L.

8. The high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The battery stack includes a positive electrode current collector, a positive electrode flow field plate, a positive electrode, an ion separator, a negative electrode, a negative electrode flow field plate and a negative electrode current collector which are arranged in sequence.

9. A method for preparing the high-voltage salt cavern aqueous organic flow battery according to claim 1, characterized in that: The following steps are involved: S1, dissolving the viologen compound in the salt cave solution to obtain the negative electrode electrolyte; S2, dissolving the cyclic nitroxide radical compound in the salt cave solution to obtain a positive electrode electrolyte; S3, placing the positive electrode electrolyte and the negative electrode electrolyte in the positive electrode storage tank and the negative electrode storage tank respectively, connecting the positive electrode storage tank, the negative electrode storage tank and the battery stack to obtain an aqueous organic liquid flow battery.

10. The preparation method according to claim 9, characterized in that In S1, the viologen compound can be a phenyl-bridged viologen molecule, a pyrazine-bridged viologen molecule or a bipyridine-bridged viologen molecule; the phenyl-bridged viologen molecule is synthesized by a Suzuki coupling reaction of 1,4-phenyldiboronic acid and a 4-bromo-pyridine derivative, the pyrazine-bridged viologen molecule is synthesized by a substitution reaction between a 4-bromo-pyridine derivative and pyrazine, and the bipyridine-bridged viologen molecule is synthesized by a substitution reaction between a 4-bromo-pyridine derivative and bipyridine.

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