An aqueous organic flow battery

Abstract

The application provides an aqueous organic liquid flow battery, and belongs to the technical field of redox flow batteries. The aqueous organic liquid flow battery comprises a positive electrolyte, a diaphragm and a negative electrolyte. The electrolyte of the positive electrolyte is electrolyte C1, C2, C3, C3i or Bn, and the electrolyte of the negative electrolyte is Dex-Vi. The positive and negative electrolytes formed by the application can endow the corresponding aqueous organic liquid flow battery with good stable output voltage.

Description

Technical Field

[0001] The present application relates to an aqueous organic liquid flow battery, belonging to the technical field of redox liquid flow batteries. Background Art

[0002] All-vanadium redox flow batteries are a relatively mature energy storage technology. However, as a rare metal, vanadium presents challenges such as high cost and limited resources. In contrast, aqueous organic flow batteries utilize diverse organic molecules as electrochemically active materials. This not only significantly reduces the cost of the redox couple but also allows for the regulation of the electrode potential, solubility, and stability of the organic active electrolyte through rational molecular design. This represents an effective approach to developing the next generation of highly safe, low-cost, and high-capacity energy storage technologies. Summary of the Invention

[0003] In view of this, the present application provides an aqueous organic liquid flow battery with a stable output voltage of up to 1.23V.

[0004] Specifically, this application is implemented through the following solutions:

[0005] An aqueous organic liquid flow battery comprises a positive electrode electrolyte, a separator, and a negative electrode electrolyte, wherein the positive electrode electrolyte, the separator, and the negative electrode electrolyte are assembled to obtain an aqueous organic liquid flow battery;

[0006] The electrolyte in the positive electrode electrolyte is any one of the following structures:

[0007] .

[0008] The electrolyte structural formula of the negative electrode electrolyte is:

[0009] .

[0010] The aqueous organic flow battery, containing the positive and negative electrolytes constructed above, has high solubility in water and a rapid redox reaction process, enabling stable charge and discharge under neutral conditions. The method of the present invention is simple, low-cost, and environmentally friendly, with excellent application prospects.

[0011] Furthermore, as a preference:

[0012] The electrolyte of the positive electrode electrolyte is prepared by the following steps:

[0013] Step 1: 2,2,6,6-tetramethylpiperidone is dissolved in deionized water, sodium bicarbonate is added, and 15% hydrogen peroxide is slowly added dropwise. After the mixture is stirred, the resulting mixture is extracted with dichloromethane, the lower organic phase is collected, and condensed and concentrated under reduced pressure to obtain the product keto TEMPO.

[0014] Step 2: Potassium tert-butoxide is dissolved in anhydrous THF, purged with nitrogen and stirred, then trimethylsulfoxide iodide is added under a nitrogen atmosphere and stirred at room temperature, and finally the keto TEMPO obtained in step 1 is slowly added. After reaction at room temperature, the resulting mixture is added to saturated potassium carbonate and stirred, directly filtered, and the filter cake is washed with dichloromethane. The filtrate is collected and extracted, and the organic phase is condensed and concentrated under reduced pressure to obtain the product epoxy TEMPO.

[0015] Step 3: Add the epoxy TEMPO obtained in step 2 to a dimethylamine aqueous solution under stirring in an ice-water bath, stir in an ice-water bath, extract, and condense and concentrate the organic phase under reduced pressure to obtain the product, ring-opened TEMPO.

[0016] Step 4, adding a substitution solution of different substituents to the open-ring TEMPO, stirring the mixture at room temperature, and then filtering the mixture, washing the filter cake with anhydrous ether, and then performing ion exchange with D-201 high-grade macroporous strong base type I anion exchange resin to exchange iodide ions for chloride ions. The aqueous solution is condensed and concentrated under reduced pressure to obtain electrolytes of each positive electrode electrolyte of the above structural formula, wherein the substitution solution is any one of iodomethane, iodoethane, iodopropane, iodopropane, and benzyl chloride solution, wherein benzyl substitution (benzyl chloride solution) does not require ion exchange.

[0017] More preferred:

[0018] The equivalent ratio of 2,2,6,6-tetramethylpiperidone to hydrogen peroxide is 10:1.

[0019] The equivalent ratio of potassium tert-butoxide, trimethylsulfoxide iodide, and keto TEMPO is 13:11:10.

[0020] The equivalent ratio of epoxy TEMPO to dimethylamine is 10:15.

[0021] The equivalent ratio of the substitution solution to the ring-opened TEMPO was 10:12.

[0022] The above preparation method systematically introduces a variety of alkyl substituents including linear, branched and aromatic groups such as methyl, ethyl, n-propyl, isopropyl and benzyl on the quaternary ammonium nitrogen atom. The resulting positive electrode electrolyte is composed of an aqueous solution of 2,2,6,6-tetramethylpiperidinyl oxide (also known as tetramethylpiperidinyl oxide, abbreviated as TEMPO) redox small molecules containing different quaternary ammonium salts.

[0023] The electrolyte of the negative electrode electrolyte is prepared by the following method:

[0024] 4,4'-bipyridine and 3-chloro-2-hydroxypropyltrimethylammonium chloride were added to a reactor lined with polytetrafluoroethylene, heated to 120 ° C, and reacted for 24 hours. After the reaction, it was cooled to room temperature and the reaction product, ethanol, and acetone were added in sequence according to the volume ratio to generate a precipitate. The solid was collected by filtration, and DMF was added to the solid, stirred at 80 ° C for 3 hours, and filtered while hot to obtain the electrolyte of the negative electrode electrolyte.

[0025] More preferred:

[0026] The equivalent ratio of 4,4'-bipyridine to 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:3.

[0027] The volume ratio of the reaction product, ethanol and acetone is 1:9:10.

[0028] The negative electrode electrolyte prepared by the above method is an aqueous solution containing quaternized viologen redox small molecules.

[0029] In the above aqueous organic flow battery:

[0030] The concentration of the electrolyte in the positive electrode electrolyte is from 0.1 mol / L to its saturation concentration.

[0031] The concentration of the electrolyte in the negative electrode electrolyte is from 0.1 mol / L to its saturation concentration.

[0032] The membrane is an anion membrane.

[0033] It also includes a supporting electrolyte, which is added to both the positive and negative electrode electrolytes. The supporting electrolyte is a mixture of any one or more of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, and sodium nitrate.

[0034] The molar concentration of the supporting electrolyte is 0.5-3 mol / L.

[0035] Beneficial results of the present invention:

[0036] 1. The active materials of the positive and negative electrolytes of the present invention exhibit obvious advantages in practical applications, including mild reaction conditions, high yield, and no need for chromatographic separation. Purification can be completed by simple precipitation and ion exchange, which is easy to achieve large-scale production. Through simple modification, the water solubility of the material can be effectively improved, thereby increasing the energy density of the battery.

[0037] 2. The six positive and negative active materials of the present invention all have fast redox kinetics, and the neutral aqueous liquid flow battery composed of them has high power density, among which the isopropyl-substituted TEMPO has the best performance.

[0038] 3. The positive electrode active material of the present invention adopts TEMPO derivatives, and the negative electrode active material adopts viologen salts, both of which are redox-active small molecules, easy to synthesize and modify, and have matching energy density and power density, so that the assembled liquid flow battery has better electrochemical performance and a stable output voltage of up to 1.23V. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 The synthetic route of the cathode electrolyte in this application;

[0041] Figure 2 The synthetic route of the negative electrode electrolyte in this application;

[0042] Figure 3 The solubility of each cathode electrolyte (C1-Bn) prepared in the examples in water;

[0043] Figure 4 Cyclic voltammetry curves of the positive and negative electrolytes prepared in the example at a scan rate of 100 mv / s;

[0044] Figure 5 The positive electrode electrolyte C1 in Example 3 is 50mA / cm 2 The electrical performance diagram below,

[0045] (a): Cycling stability performance diagram, (b): Charge and discharge curve;

[0046] Figure 6 The positive electrolyte C2 in Example 3 is 50mA / cm 2 The electrical performance diagram below,

[0047] (a): Cycling stability performance diagram, (b): Charge and discharge curve;

[0048] Figure 7 The positive electrolyte C3 in Example 3 is 50mA / cm 2 The electrical performance diagram below,

[0049] (a): Cycling stability performance diagram, (b): Charge and discharge curve;

[0050] Figure 8 The positive electrode electrolyte C3i in Example 3 is 50mA / cm 2 The electrical performance diagram below,

[0051] (a): Cycling stability performance diagram, (b): Charge and discharge curve;

[0052] Figure 9 The positive electrode electrolyte Bn in Example 3 is 50mA / cm 2 The electrical performance diagram below,

[0053] (a): Cycling stability performance diagram, (b): Charge and discharge curve;

[0054] Figure 10 The positive electrode electrolyte 4-hydroxy-Tempo in the comparative example is 50mA / cm 2 The electrical performance diagram below,

[0055] (a): Cycling stability performance diagram, (b): Charge and discharge curve. DETAILED DESCRIPTION

[0056] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the technical solutions in the embodiments of this application will be further described in detail below in conjunction with the drawings in the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the technical solutions of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of this application.

[0057] Example 1

[0058] This example is used to prepare the positive electrode electrolyte.

[0059] See Figure 1 , Figure 1 Shown are the synthesis routes of various cathode electrolytes.

[0060] The general formula of the positive electrode electrolyte is: , R are methyl, ethyl, n-propyl, isopropyl and benzyl, respectively, which are denoted as positive electrode electrolyte C1, positive electrode electrolyte C2, positive electrode electrolyte C3, positive electrode electrolyte C3i and positive electrode electrolyte Bn.

[0061] The preparation process of each cathode electrolyte is as follows:

[0062] Step 1: Add 40 g of 2,2,6,6-tetramethylpiperidone to a 500 mL round-bottom flask and dissolve in 120 mL of deionized water. Add 4 g of sodium bicarbonate and slowly add 100 mL of 15% hydrogen peroxide dropwise. Stir the mixture for 24 hours until it turns red. Extract the resulting mixture with dichloromethane, collecting the lower organic phase. Repeat this process three times. Dry the organic phase over anhydrous ammonium sulfate, collect the filtrate by filtration, and concentrate the filtrate under reduced pressure to obtain keto-TEMPO in a 91% yield.

[0063] Step 2: Add 26.37 g of potassium tert-butoxide to a 1000 ml two-necked round-bottom flask equipped with a rotor and purge with nitrogen for 10 minutes. Then, add 400 ml of anhydrous THF and stir for 30 minutes. Then, under a nitrogen atmosphere, add 56.88 g of trimethylsulfoxide iodide and stir at room temperature for 30 minutes until no bubbles form. Finally, slowly add 40 g of keto-TEMPO dissolved in 100 ml of anhydrous THF and react at room temperature for 5 hours. Add 100 ml of saturated potassium carbonate to the resulting mixture, stir for 10 minutes, filter directly, and wash the filter cake with dichloromethane. Collect the filtrate, extract three times with water, and collect the organic phase. Dry the organic phase over anhydrous sodium sulfate, and concentrate the filtrate under reduced pressure to obtain the product, epoxy TEMPO, in a yield of 86.3%.

[0064] Step 3: Add 25 g of epoxy TEMPO to a 100 ml round-bottom flask equipped with a rotor. Add a 40% aqueous dimethylamine solution while stirring in an ice-water bath. Stir in an ice-water bath for 8 hours, then extract the mixture three times with dichloromethane. Collect the lower organic phase. Dry the organic phase over anhydrous sodium sulfate, and concentrate the filtrate under reduced pressure to obtain ring-opened TEMPO in a 90% yield.

[0065] Step 4: The substitution solutions of different substituents (4.64 g iodomethane solution, 5.1 g iodoethane solution, 5.56 g iodopropane solution, 5.56 g iodopropane solution, and 5.59 g benzyl chloride solution) were respectively added to 5 g of open-ring TEMPO, and the mixture was stirred at room temperature for 12 hours. After that, the mixture was filtered, the filter cake was washed with anhydrous ether, and then ion exchange was carried out with D-201 high-grade macroporous strong base type I anion exchange resin. The ions were exchanged three times to exchange iodide ions for chloride ions. The aqueous solution was condensed and concentrated under reduced pressure. The obtained products were recorded as: positive electrode electrolyte C1, positive electrode electrolyte C2, positive electrode electrolyte C3, positive electrode electrolyte C3i, and positive electrode electrolyte Bn (ion exchange is not required during the preparation process).

[0066] Example 2

[0067] This example is about preparing the negative electrode electrolyte.

[0068] See Figure 2 , Figure 2The synthesis route of the negative electrode electrolyte is shown. The corresponding electrolyte is recorded as the negative electrode electrolyte Dex-Vi, and the structural formula is:

[0069] .

[0070] The negative electrode electrolyte, Dex-Vi, was prepared as follows: 4,4'-bipyridine (4 g, 1 eq, 25.61 mmol) and 3-chloro-2-hydroxypropyltrimethylammonium chloride (20 ml, 2.9 eq, 65% aqueous solution) were added to a Teflon-lined reactor and heated to 120°C for 24 hours. After the reaction, the mixture was cooled to room temperature. A precipitate was formed by adding the product: ethanol: acetone (1:9:10) in that order. The solid was collected by filtration. DMF was added to the solid, stirred at 80°C for 3 hours, and filtered while hot to collect 10.36 g of a white solid, representing the negative electrode electrolyte, Dex-Vi, with a yield of 76%.

[0071] Performance testing:

[0072] 1) Solubility test:

[0073] The test method is as follows: the positive electrode electrolytes (C1-Bn) prepared in Example 1 are dissolved in water, and the solubility of the five positive electrode electrolytes (C1-Bn) is accurately measured by ultraviolet-visible spectroscopy.

[0074] Test results: See Figure 3 , Figure 3 The solubility of the positive electrode electrolyte in water is shown. The solubility of the positive electrode electrolyte C1 is about 2.3 mol / L, the solubility of the positive electrode electrolyte C2 is about 2.55 mol / L, the solubility of the positive electrode electrolyte C3 is about 2.25 mol / L, the solubility of the positive electrode electrolyte C3i is about 2.0 mol / L, and the solubility of the positive electrode electrolyte Bn is about 1.6 mol / L. As a control, HOTEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical) is 2.3 mol / L. The solubility of the electrolytes prepared in this application is generally high.

[0075] 2) Cyclic voltammetry curve test:

[0076] The positive electrolyte (C1-Bn) prepared in Example 1 was dissolved in 10 ml of a 0.5 mol / L potassium chloride aqueous solution to obtain a positive electrolyte solution. The concentration of the positive electrolyte (C1-Bn) in the solution was 5 mmol / L. This positive electrolyte solution was exposed to nitrogen gas to remove oxygen while conducting three-electrode cyclic voltammetry. A glassy carbon electrode was used as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum electrode as the counter electrode. The scan rate was 100 mV / s and the voltage range was 0-1.1 V.

[0077] The negative electrode electrolyte Dex-Vi prepared in Example 2 was dissolved in 10 ml of a 0.5 mol / L potassium chloride aqueous solution to obtain a negative electrode electrolyte solution. The concentration of the negative electrode electrolyte Dex-Vi was 5 mmol / L. This negative electrode electrolyte solution was exposed to nitrogen and deoxygenated while undergoing cyclic voltammetry using a three-electrode system. A glassy carbon electrode was used as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum electrode as the counter electrode. The scan rate was 100 mV / s and the voltage range was -1.2 to 0 V.

[0078] See Figure 4 , Figure 4 The cyclic voltammograms of the positive electrode electrolyte containing C3i and the negative electrode electrolyte containing Dex-Vi at a scan rate of 100 mv / s are shown. It can be seen that both materials have reversible redox reactions, and a potential difference of up to 1.23 V is formed between the positive and negative electrode electrolytes, which has a potential difference that matches that of aqueous electrolytes.

[0079] Example 3

[0080] This embodiment provides an aqueous organic liquid flow battery.

[0081] The positive electrode electrolyte solution consists of: 0.1 mol / L of the positive electrode electrolyte (C1-Bn) synthesized in Example 1, 1 mol / L of potassium chloride, and 5 ml of solvent water.

[0082] Negative electrode electrolyte: 0.1 mol / L of the negative electrode electrolyte Dex-Vi synthesized in Example 2, 1 mol / L potassium chloride and 5 ml of solvent water.

[0083] The diaphragm adopts anion diaphragm (MTCP-50, 2.5 2.5 cm).

[0084] The positive electrode electrolyte, separator and negative electrode electrolyte were assembled to obtain five groups of aqueous organic liquid flow batteries, and each aqueous organic liquid flow battery was subjected to charge and discharge tests and cycle stability experiments.

[0085] Test method: first set it to stand for 30 minutes, then perform constant current charging (current 200mA, voltage upper limit 1.4V) and constant current discharging (current 200mA, voltage lower limit 0.7V) cycle test 1000 times, the flow rate of the peristaltic pump is 50rpm, and finally end the test. Figures 5 to 9 The following are the cycle stability and charge-discharge curves of different positive electrode electrolytes (C1~Bn) as positive electrode materials for flow batteries under 1000 cycles.

[0086] Through constant current charge and discharge tests, we found that our aqueous organic flow battery composed of positive electrolyte (C1~Bn) and negative electrolyte Dex-Vi has charge and discharge cycle stability, a coulombic efficiency close to 100%, and a stable output voltage of 1.23V (see Figures 5 to 9 ), the neutral aqueous organic flow battery has high safety and stable charge and discharge. Figures 5 to 9 It can be seen that different substituents have a significant impact on the performance of the positive electrode electrolyte. For example, the discharge capacity of the positive electrode electrolyte C2 corresponding to the ethyl derivative decays rapidly and the energy efficiency is low (see Figure 6 (a) in the figure). The positive electrode electrolyte C3i represented by isopropyl showed the best cycle performance in the test, with the most stable energy efficiency and voltage platform, and is the electrolyte material with the best comprehensive performance in this series of materials (see Figure 8 (a) in the figure.

[0087] Although the initial capacities of all cathode electrolytes (C1~Bn) are close to 2.68 Ah L -1 The theoretical values ​​are different, but the charge and discharge performance is different: the capacities of the first cycle of C1~Bn are approximately 2.42, 2.43, 2.28, 1.89, and 2.35 Ah L -1 (See Figure 5 Middle (b), Figure 6 Middle (b), Figure 7 Middle (b), Figure 8 Middle (b), Figure 9 (b) Voltage versus capacity curve), but at a current density of 50 mA cm -2 In the case of Figure 5 Middle (a), Figure 6 Middle (a), Figure 7 Middle (a), Figure 8 Middle (a), Figure 9 The discharge capacity changes with the number of cycles in (a)). Among them, the positive electrode electrolyte C3i shows excellent cycle stability and can still maintain 99.41% of the initial capacity after 1000 cycles (see Figure 8 In contrast, the cathode electrolyte C1, despite having the highest energy efficiency and excellent redox kinetics, exhibits a more pronounced capacity decay, retaining only 97.18% of its initial capacity after 1000 cycles (see Figure 5 (a) in Figure 1). The stability of the positive electrolytes C2, C3, and Bn is relatively poor, with capacity retention rates of 95.33%, 96.53%, and 96.27%, respectively (see Figure 1). Figure 6 (a) in Figure 7 (a) in Figure 9 (a) in the figure.

[0088] Comparative Example

[0089] This comparative example provides a traditional aqueous organic liquid flow battery.

[0090] The positive electrode electrolyte consists of 0.1 mol / L 4-hydroxy-TEMPO, 1 mol / L potassium chloride and 5 ml of solvent water.

[0091] Negative electrode electrolyte: 0.1 mol / L of the negative electrode electrolyte Dex-Vi synthesized in Example 2, 1 mol / L potassium chloride and 5 ml of solvent water.

[0092] The diaphragm adopts anion diaphragm (MTCP-50, 2.5 2.5 cm).

[0093] The test method is the same as in Example 3. The test results are as follows Figure 10 As shown: Although the initial capacity of 4-hydroxy-TEMPO is close to the theoretical capacity, the capacity retention rate is 85.77% after 50 cycles (see Figure 10 (a) in Example 3), which is lower than that of C1~Bn in Example 3. In addition, 4-hydroxy-TEMPO showed a higher voltage platform decay trend during the cycle (see Figure 10 (b) in the figure shows that its stability and energy efficiency are lower than those of the TEMPO derivative series of this application. The quaternized TEMPO derivatives designed in this application exhibit superior electrochemical stability, higher capacity retention, and a more stable operating voltage platform in a neutral aqueous environment, demonstrating their technical advantages in liquid flow battery systems.

[0094] The above-described embodiments merely represent several feasible implementation methods of the present invention. The description thereof is relatively specific and detailed, but it should not be understood as limiting the scope of the invention. The embodiments are not intended to limit the scope of protection in the claims of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention. Any equivalent implementation or modification that does not depart from the scope of the present invention should be included in the technology of the present invention.

Claims

1. An aqueous organic liquid flow battery comprising a cathode electrolyte, a separator, and a cathode electrolyte, characterized in that: The electrolyte in the positive electrode electrolyte is any one of the following structures: ， The electrolyte structural formula of the negative electrode electrolyte is: 。 2. The aqueous organic liquid flow battery according to claim 1, characterized in that: The electrolyte of the positive electrode electrolyte is prepared by the following steps: Step 1: 2,2,6,6-tetramethylpiperidone is dissolved in deionized water, sodium bicarbonate is added, and 15% hydrogen peroxide is slowly added dropwise. The mixture is stirred and extracted with dichloromethane. The lower organic phase is collected and concentrated under reduced pressure to obtain the product keto-TEMPO. Step 2: Dissolve potassium tert-butoxide in anhydrous THF, blow nitrogen and stir, then add trimethylsulfoxide iodide under nitrogen atmosphere and stir at room temperature, slowly add the keto TEMPO obtained in step 1, react at room temperature, add saturated potassium carbonate and stir, filter, wash, collect the filtrate, extract, and condense the organic phase under reduced pressure to obtain the product epoxy TEMPO; Step 3: Add the epoxy TEMPO obtained in step 2 to a dimethylamine aqueous solution, stir under ice bath, extract, and condense the organic phase under reduced pressure to obtain the product, ring-opened TEMPO; Step 4: add the substitution solution to the open-ring TEMPO and stir at room temperature, filter, wash the filter cake with anhydrous ether, and then exchange ions with D-201 high-grade macroporous strong base type I anion exchange resin. The obtained aqueous solution is condensed and concentrated under reduced pressure to obtain the electrolyte of the positive electrode electrolyte. The substitution solution is any one of iodomethane, iodoethane, iodopropane, iodopropane, and benzyl chloride solution. When the substitution solution is benzyl chloride solution, ion exchange is not required.

3. The aqueous organic flow battery according to claim 2, characterized in that: The equivalent ratio of 2,2,6,6-tetramethylpiperidone to hydrogen peroxide was 10:1, the equivalent ratio of potassium tert-butoxide, trimethylsulfoxide iodide, and keto TEMPO was 13:11:10, the equivalent ratio of epoxy TEMPO to dimethylamine was 10:15, and the equivalent ratio of the substitution solution to open-ring TEMPO was 10:

12.

4. The aqueous organic flow battery according to claim 1, characterized in that: The electrolyte of the negative electrode electrolyte is prepared by the following method: 4,4'-bipyridine and 3-chloro-2-hydroxypropyltrimethylammonium chloride are added to a reactor with a polytetrafluoroethylene liner, reacted at 120°C for 24 hours, cooled to room temperature, ethanol and acetone are added to the reaction product in sequence to generate a precipitate, the solid is collected by filtration, DMF is added to the solid, stirred at 80°C for 3 hours, and filtered while hot to obtain the electrolyte of the negative electrode electrolyte.

5. The aqueous organic liquid flow battery according to claim 4, characterized in that: The equivalent ratio of 4,4'-bipyridine and 3-chloro-2-hydroxypropyltrimethylammonium chloride is 1:3, and the volume ratio of the reaction product, ethanol, and acetone is 1:9:

10.

6. The aqueous organic flow battery according to claim 1, characterized in that: The electrolyte concentration in the positive electrode electrolyte is ≥0.1 mol / L.

7. The aqueous organic flow battery according to claim 1, characterized in that: The electrolyte concentration in the negative electrode electrolyte is ≥0.1 mol / L.

8. The aqueous organic flow battery according to claim 1, characterized in that: The membrane is an anion membrane.

9. The aqueous organic flow battery according to any one of claims 1 to 8, characterized in that: It also includes a supporting electrolyte, which is a mixture of any one or more of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, and sodium nitrate. The supporting electrolyte is added to both the positive and negative electrolytes.

10. The aqueous organic flow battery according to claim 9, characterized in that: The molar concentration of the supporting electrolyte is 0.5-3 mol / L.

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