An aqueous redox flow battery

Abstract

The application provides a water-based redox flow battery, and belongs to the technical field of energy storage systems. The water-based redox flow battery comprises a positive electrolyte, a diaphragm and a negative electrolyte. The active substance of the positive electrolyte is 4,4'-azopyridine, and the active substance of the negative electrolyte is 2,7-di(quinolinium acetylamino)pyrene-4,5,9,10-tetraone. The flow battery has the advantages of high specific capacity, excellent stability and the like.

Description

Technical Field

[0001] This application relates to an aqueous redox flow battery, belonging to the field of energy storage system technology. Background Technology

[0002] Flow batteries, as an emerging electrochemical energy storage system, mainly consist of a stack unit, electrolyte, electrolyte storage and supply unit, and external control unit. Their core working principle is as follows: the separate positive and negative electrode electrolytes circulate through the electrolyte storage and supply unit, while the dissolved active materials in the electrolyte undergo reversible redox reactions within the battery's stack unit, ultimately achieving the interconversion of electrical energy and chemical energy. This structure and working principle also allow for relatively independent design of the output power and capacity of flow batteries.

[0003] However, traditional flow batteries have many shortcomings in electrolyte composition and electrode material development, which greatly limit the performance optimization and application expansion of flow batteries. Summary of the Invention

[0004] In view of this, this application provides an aqueous redox flow battery with advantages such as high specific capacity and excellent stability.

[0005] Specifically, this application is implemented through the following scheme: An aqueous redox flow battery includes a positive electrode electrolyte, a separator, and a negative electrode electrolyte. The active material of the positive electrode electrolyte is 4,4'-azopyridine (4,4'-AZPY), and the active material of the negative electrode electrolyte is 2,7-bis(quaternary ammonium acetamyl)pyrene-4,5,9,10-tetraone (DQA-PTO).

[0006] Furthermore, as a preferred option: The active material of the negative electrode electrolyte is prepared by the following steps: Step 1: Dissolve pyrene in a mixed solvent of dichloromethane and acetonitrile, then add sodium periodate, water, and ruthenium trichloride hydrate in sequence, stir and react to obtain pyrene-4,5,9,10-tetraone (PTO).

[0007] Step 2: Pyrene-4,5,9,10-tetraone (PTO) is added to a mixed solution of concentrated sulfuric acid and fuming nitric acid, the mixture is stirred and reacted, the solid is precipitated in deionized water, filtered and collected, and dried to obtain 2,7-dinitro-pyrene-4,5,9,10-tetraone (DNO2-PTO).

[0008] Step 3: 2,7-dinitro-pyrene-4,5,9,10-tetraone (DNO2-PTO), sodium hydroxide, and sodium dithionite were added to deionized water and stirred. After stirring, the mixture was precipitated in a saturated ammonium chloride solution, filtered, washed with an appropriate amount of deionized water, and the solid was collected and dried. The dried solid and dichlorodicyanoquinone were added to anhydrous methanol and stirred. The mixture was then precipitated in ethyl acetate, filtered, washed with ethyl acetate, and the solid was collected and dried to obtain 2,7-diamino-pyrene-4,5,9,10-tetraone (DNH2-PTO).

[0009] Step 4: Dissolve 2,7-diamino-pyrene-4,5,9,10-tetraone (DNH2-PTO) in DMF, add chloroacetyl chloride, stir the reaction, precipitate in water, filter and collect the solid to obtain 2,7-bis(chloroacetamyl)pyrene-4,5,9,10-tetraone (DCA-PTO).

[0010] Step 5: Dissolve 2,7-bis(chloroacetamyl)pyrene-4,5,9,10-tetraone (DCA-PTO) in DMF, add trimethylamine ethanol solution, stir the reaction, precipitate in acetone, collect the solid, and separate 2,7-bis(quaternized acetamyl)pyrene-4,5,9,10-tetraone (DQA-PTO).

[0011] Furthermore, the preferred settings for each step are as follows: In step one, The volume ratio of dichloromethane, acetonitrile, and water is 1:1 to 1.5:1.2 to 1.3, preferably 1:1:1.25.

[0012] The equivalent ratio of pyrene, sodium periodate, and ruthenium trichloride hydrate is 1:0.1-0.2:6-10, preferably 1:0.15:8.

[0013] After adding sodium periodate, water, and ruthenium trichloride hydrate, stir and react overnight at 30–50°C.

[0014] In step two, The volume ratio of fuming nitric acid to concentrated sulfuric acid is 1:2 to 5, preferably 1:3.

[0015] Pyrene-4,5,9,10-tetraone was added to a mixed solution of concentrated sulfuric acid and fuming nitric acid and stirred overnight at 100–120°C.

[0016] In step three, The equivalent ratio of 2,7-dinitro-pyrene-4,5,9,10-tetraone (DNO2-PTO), sodium hydroxide, sodium dithionite, and dichlorodicyanoquinone is 1:300-400:40-50:10-20, preferably 1:350:40:15.

[0017] 2,7-Dinitro-pyrene-4,5,9,10-tetraone, sodium hydroxide, and sodium dithionite were added to deionized water and stirred at 40–60°C for 10–60 minutes.

[0018] The dried solid and dichlorodicyanoquinone were added to anhydrous methanol and stirred at 30–40 °C for 10–20 hours.

[0019] In step four, The equivalent ratio of 2,7-diamino-pyrene-4,5,9,10-tetraone (DNH2-PTO) to chloroacetyl chloride is 1:2 to 3, preferably 1:3.

[0020] Add chloroacetyl chloride and stir the mixture at 30–40°C for 1–3 hours.

[0021] In step five, The equivalent ratio of 2,7-bis(chloroacetamido)pyrene-4,5,9,10-tetraone (DCA-PTO) to trimethylamine is 1:10 to 15, preferably 1:10.

[0022] Add trimethylamine ethanol solution and stir the mixture at 40–50°C for 24–60 hours.

[0023] The active material of the positive electrode electrolyte is prepared by the following method: 4-p-aminopyridine is dissolved in deionized water, sodium hypochlorite solution is added dropwise and the reaction is stirred, and then separated and dried to obtain 4,4'-azopyridine (4,4'-AZPY). More preferably, The equivalent ratio of 4-p-aminopyridine to sodium hypochlorite is 1:5 to 8, preferably 1:6.

[0024] The sodium hypochlorite solution was added dropwise and stirred at -20 to -5°C. After the addition was complete, the mixture was stirred at this temperature for 1 to 3 hours.

[0025] The concentration of active material in the positive electrode electrolyte is 0.06~0.6 mol / L.

[0026] The concentration of active material in the negative electrode electrolyte is 0.02~0.2 mol / L.

[0027] The membrane is an anion exchange membrane, such as the MTCP-50 AEM exchange membrane, which prevents the positive electrolyte from directly contacting the negative electrolyte while allowing the free shuttle of supporting electrolyte ions in the electrolyte to ensure the charge balance of the electrolytes on both sides.

[0028] In the above-described aqueous redox flow battery, 4,4'-azopyridine (4,4'-AZPY) is dissolved in an aqueous sulfuric acid solution to obtain the positive electrode electrolyte, and 2,7-bis(quaternary ammonium acetamyl)pyrene-4,5,9,10-tetraone (DQA-PTO) is dissolved in an aqueous sulfuric acid solution to obtain the negative electrode electrolyte. The positive electrode electrolyte, the negative electrode electrolyte, and the separator are assembled to form the flow battery. More preferably, the concentration of the aqueous sulfuric acid solution is 4.6 mol / L, and the aqueous sulfuric acid solution exists as the supporting electrolyte of the battery.

[0029] This application utilizes the synergy between the positive and negative electrode electrolytes to enable 4,4'-AZPY, which exhibits excellent redox performance and stability, to undergo a reversible redox reaction with DQA-PTO. In terms of electrochemical performance, this endows the flow battery with excellent redox performance and stability, effectively improving the battery's energy density and cycle life. Furthermore, the good stability of the active materials in both the positive and negative electrode electrolytes effectively enhances the cycle stability of the flow battery. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application.

[0031] Figure 1 The electrochemical properties of 5 mM DQA-PTO in 4.6 mol / L sulfuric acid aqueous solution were measured by cyclic voltammetry (CV). Part (a) of the figure is the current-voltage curve at different scan rates, and part (b) is the relationship between the oxidation peak current and the reduction peak current and the square root of the scan rate.

[0032] Figure 2 The electrochemical properties of 5 mM DQA-PTO in 4.6 mol / L sulfuric acid aqueous solution were measured using rotating disk electrode-linear scanning voltammetry (RDE-LSV). Part (a) of the figure shows the current-voltage curves at different rotation speeds, part (b) shows the Levich curve of limiting current versus the square root of angular velocity, part (c) shows the relationship between the reciprocal of limiting current and the reciprocal of the square root of angular velocity at different overpotentials, and part (d) shows the Tafel curve obtained by the logarithm of overpotential and kinetic current value.

[0033] Figure 3 Image showing the redox potential difference between DQA-PTO and 4,4'-AZPY in this application.

[0034] Figure 4 Images showing the rate performance of the flow battery of this application at different current densities.

[0035] Figure 5The images show the charge-discharge curves of the flow battery of this application at different current densities.

[0036] Figure 6 12.5 mA / cm 2 The image shows the long-cycle performance at current density. Part (a) of the image shows the long-cycle performance of the flow battery of this application, and part (b) shows the charge-discharge curves at different numbers of cycles.

[0037] Figure 7 Images showing the power density of the flow battery under different states of charge according to this application.

[0038] Figure 8 This is to demonstrate the long-cycle performance of the battery in Comparative Example 3. Detailed Implementation

[0039] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the technical solutions in the embodiments of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit the technical solutions of this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.

[0040] Example 1

[0041] This embodiment provides an aqueous redox flow battery, including a positive electrode electrolyte, a separator, and a negative electrode electrolyte. The positive electrode electrolyte uses 4,4'-AZPY as the active material, and the negative electrode electrolyte uses DQA-PTO as the active material.

[0042] The assembly process of the above-mentioned aqueous redox flow battery is as follows: (1) Preparation of positive electrode electrolyte: 4-p-aminopyridine and sodium hypochlorite were dissolved in deionized water according to the equivalent ratio of 4-p-aminopyridine to sodium hypochlorite of 1:6. Sodium hypochlorite solution was added dropwise at -10℃ and the reaction was stirred for 2 hours. After separation and drying, 4,4'-azopyridine (4,4'-AZPY) was obtained. 4,4'-AZPY was added to 21 mL of 4.6 mol / L sulfuric acid aqueous solution to obtain a positive electrode electrolyte with a concentration of 0.2 M of 4,4'-AZPY.

[0043] (2) Preparation of negative electrode electrolyte: Step 1: Pyrene was dissolved in dichloromethane and acetonitrile, and sodium periodate, water, and ruthenium trichloride hydrate were added sequentially. The mixture was stirred overnight at 40°C to obtain pyrene-4,5,9,10-tetraone (PTO). The volume ratio of dichloromethane, acetonitrile, and water was 1:1:1.25, and the equivalent ratio of pyrene, sodium periodate, and ruthenium trichloride hydrate was 1:0.15:8.

[0044] Step 2: Pyrene-4,5,9,10-tetraone (PTO) was added to a mixed solution of concentrated sulfuric acid and fuming nitric acid (volume ratio of fuming nitric acid to concentrated sulfuric acid was 1:3). The mixture was stirred overnight at 110°C. The solid was precipitated in deionized water, filtered, collected, and dried to obtain 2,7-dinitro-pyrene-4,5,9,10-tetraone (DNO2-PTO).

[0045] Step 3: 2,7-dinitro-pyrene-4,5,9,10-tetraone (DNO2-PTO), sodium hydroxide, and sodium dithionite were added to deionized water and stirred at 50°C for 30 minutes. The precipitate was collected in a saturated ammonium chloride solution, filtered, washed with an appropriate amount of deionized water, and dried. The dried solid and dichlorodicyanoquinone were added to anhydrous methanol and stirred at 35°C for 16 hours. The precipitate was then collected in ethyl acetate, filtered, washed with ethyl acetate, and dried to obtain 2,7-diamino-pyrene-4,5,9,10-tetraone (DNH2-PTO). The equivalent ratio of 2,7-dinitro-pyrene-4,5,9,10-tetraone (DNO2-PTO), sodium hydroxide, sodium dithionite, and dichlorodicyanoquinone was 1:350:40:15.

[0046] Step four: Dissolve 2,7-diamino-pyrene-4,5,9,10-tetraone (DNH2-PTO) in DMF, add chloroacetyl chloride, stir overnight at room temperature, precipitate in water, filter and collect the solid to obtain 2,7-bis(chloroacetamamido)pyrene-4,5,9,10-tetraone (DCA-PTO). The equivalent ratio of 2,7-diamino-pyrene-4,5,9,10-tetraone (DNH2-PTO) to chloroacetyl chloride is 1:3.

[0047] Step 5: Dissolve 2,7-bis(chloroacetamyl)pyrene-4,5,9,10-tetraone (DCA-PTO) in DMF, add trimethylamine ethanol solution, stir and react at 45°C for 48 hours, precipitate in acetone, collect the solid, and separate 2,7-bis(quaternized acetamyl)pyrene-4,5,9,10-tetraone (DQA-PTO). The equivalent ratio of 2,7-bis(chloroacetamyl)pyrene-4,5,9,10-tetraone (DCA-PTO) to trimethylamine is 1:10.

[0048] Step 6: Add DQA-PTO to 7 mL of 4.6 mol / L sulfuric acid aqueous solution to obtain a negative electrode electrolyte with a DQA-PTO concentration of 0.2 M.

[0049] (3) Assemble the battery: The positive electrode electrolyte, negative electrode electrolyte and battery stack (generally including plates, current collectors and separators; in this embodiment, the separator is an MTCP-50-AEM separator) are assembled in sequence to obtain an aqueous redox flow battery.

[0050] The above batteries were subjected to performance testing: 1. CV curves: Recorded using a ZIVE SP1 electrochemical workstation. Tests were performed using a glassy carbon working electrode, an Ag / AgCl reference electrode, and a platinum wire counter electrode. The test results are as follows: Figure 1 As shown: CV curves were tested at different voltages (20mV, 40mV, 60mV, 80mV, 100mV). DQA-PTO exhibited excellent reversible redox performance in the 4.6mol / L sulfuric acid system, and its redox potential did not change significantly with the rate of voltage change (see...). Figure 1 (part (a) in the text). Figure 1 In part (b), the average median voltage of DQA-PTO was calculated to be 380.18 mV. pc / i pa The value was 1.86, confirming that DQA-PTO has a relatively low redox potential and good electrochemical reversibility in the 4.6 mol / L sulfuric acid system.

[0051] 2. RDE-LSV curves: Recorded using a SIN-RDE type rotating disk electrode apparatus and a ZIVE SP1 electrochemical workstation. Tests were performed using a glassy carbon working electrode, an Ag / AgCl reference electrode, and a platinum wire counter electrode. The test results are as follows: Figure 2 As shown: RDE-LSV testing was conducted at a rate of 10 mV / s, with the rotation speed of the rotating disk electrode assembly gradually increasing from 400 rpm to 4000 rpm. At each rotation speed, the RDE-LSV curves showed a mass transfer-controlled limiting current and exhibited a distinct current plateau (see [link to RDE-LSV test]). Figure 2 (part (a) in the text).

[0052] The limiting current (I) of DQA-PTO in a 4.6 mol / L sulfuric acid system shows a clear linear relationship with the square root of the rotational speed (angular velocity) (see...). Figure 2 (b) in the equation conforms to the Levich equation.

[0053] Under different voltages (e.g., 10mV, 20mV, 30mV, 40mV, 50mV), the limiting current (I) still shows a consistent trend with the rotational speed (angular velocity) (e.g.) Figure 2 (Part (c))

[0054] Based on the Levich equation for DQA-PTO in a 4.6 mol / L sulfuric acid system, with a slope of 6.05, the calculated diffusion coefficient D0 is 5.46 × 10⁻⁶. -6 cm 2 / s. To determine the rate constant during charge transfer, the overpotential (η) and logarithm of the kinetic current (Logi) of DQA-PTO in a 4.6 mol / L sulfuric acid system were further plotted. K Tafel curve () Figure 2 (d) of the text). The electron transfer rate constant k0 obtained from the fitted Tafel curve is 2.04 × 10⁻⁶. -3 cm 2 / s, high-concentration acid environment improves the electron transfer capability of DQA-PTO. LSV curve data shows that DQA-PTO has excellent diffusion performance and excellent electron transfer capability in aqueous system, and is a potential electrode material for flow battery.

[0055] The applicant further tested and compared the differences between the active materials of the positive and negative electrode electrolytes in this application, and the results are as follows: Figure 3 As shown, the redox potential difference between the two is 238mV, indicating that the flow battery of this application can provide an output voltage of about 0.25V, demonstrating good battery performance.

[0056] The flow battery was tested for rate performance at different current densities, and the corresponding rate performance curves and charge-discharge curves were obtained, such as... Figure 4 , Figure 5 As shown: This flow battery operates at 1.25 mA / cm². 2 It has a high energy density, and at 25 mA / cm². 2 The material maintains its stability even at high current densities, and this stability is further enhanced when the current density is adjusted back to 1.25 mA / cm². 2 At that time, the battery capacity was restored without any degradation.

[0057] Figure 6 The results of the long-cycle performance test of the flow battery of this application are as follows: The flow battery using 4,4'-AZPY and DQA-PYO as positive and negative electrode active materials can still maintain 100% of the high battery capacity after 400 cycles, and its capacity decay is 0.

[0058] Figure 7 The power density images of the flow battery of this application at different states of charge are shown: the flow battery exhibits 4.9 mW / cm² at 50% and 100% states of charge, respectively. 2 and 5.8mW / cm 2 The output power demonstrates that the flow battery has good power density performance.

[0059] Comparative Example 1

[0060] Using CN122647485A as Comparative Example 1, this comparative example provides two traditional aqueous flow batteries: Positive electrode electrolyte 1 consists of: 5 mM / L PTO-1, 1 M / L sodium chloride, and 20 ml of water. Negative electrode electrolyte 1 consists of: 5 mM / L PTO-1, 1 M / L sodium chloride, and 20 ml of water. The diaphragm is a cation exchange diaphragm (sPEEK-Trip, 5.5cm*5.5cm).

[0061] Test method: The successfully assembled aqueous organic flow battery was subjected to charge-discharge cycle test at a current density of 20 mA / cm², a charge cut-off voltage of 2.5V, and a discharge cut-off voltage of 0.5V. The experimental results showed that the battery retained a capacity of up to 98.19% after 300 cycles.

[0062] Positive electrode electrolyte 2 consists of: 5 mM / L PTO-2, 1 M / L sodium chloride, and 20 ml of water. Negative electrode electrolyte 2 consists of: 5 mM / L PTO-2, 1 M / L sodium chloride, and 20 ml of water. The diaphragm is a cation exchange diaphragm (sPEEK-Trip, 5.5cm*5.5cm).

[0063] Test method: The successfully assembled aqueous organic flow battery was tested at 20 mA / cm². 2 The battery was subjected to charge-discharge cycle tests at a current density of 2.5V and a discharge cutoff voltage of 0.5V. The experimental results showed that the battery retained a capacity of up to 97.22% after 300 cycles.

[0064] The core design of Comparative Example 1 involves the diazapyrene / diazapyrene skeleton itself participating in subsequent quaternization, while Example 1 employs a functional partitioning molecular design, retaining the original redox center for energy storage and introducing quaternized side chains at positions 2 and 7 to improve molecular water solubility. Both flow batteries in Comparative Example 1 exhibited capacity decay after 300 cycles, while in Example 1, DQA-PTO and 4,4'-AZPY formed a specific positive and negative electrode combination. The system demonstrated good redox reversibility, mass transfer, and electron transfer kinetics in 4.6 mol / L sulfuric acid medium, thus exhibiting good cycling stability at the flow battery level, with no capacity decay after 400 cycles.

[0065] Comparative Example 2

[0066] CN121270436A is used as comparative example 2.

[0067] Comparative Example 2 uses a sulfonic acid-modified PTO derivative as the positive electrode active material and forms an aqueous organic flow battery with an inorganic negative electrode active material. Representative examples of this battery were tested using a 3 mol / L sulfuric acid electrolyte, a 0.12 mol / L PTO-PTS positive electrode electrolyte, and a V(II) negative electrode electrolyte. Example 1, on the other hand, uses a flow battery system with synergistic organic materials. In Comparative Example 2, the core design optimizes the solubility structure through sulfonic acid groups to improve water solubility and utilizes their electron-withdrawing effect to increase the electrode potential. Example 1, however, does not simply follow the approach of Comparative Example 2, which uses sulfonic acid groups to improve water solubility. Instead, it introduces a quaternized acetamide side chain with completely different chemical properties, altering the polarity of the PTO molecule, the electronic environment around the PTO molecule core, and the diffusion and electron transfer behavior of the molecule, resulting in comprehensive performance suitable for flow batteries. Example 1 has a completely different molecular structure and an all-organic positive and negative electrode system than Comparative Example 2, and achieves good oxygen reduction kinetics, positive and negative electrode potential matching, and cycle stability, showing no capacity decay after 400 stable cycles.

[0068] Comparative Example 3 This comparative example provides a conventional aqueous flow battery: Positive electrode electrolyte composition: 80mM / LV 4+ 4.6 mol / L sulfuric acid aqueous solution; The negative electrode electrolyte consists of 20 mM / L DQA-PTO and 4.6 mol / L sulfuric acid aqueous solution. The diaphragm is an anion exchange membrane (MTCP-50, 2.5*2.5 cm).

[0069] The testing method is the same as in Example 1. The test results are as follows: Figure 8 As shown, under DQA-PTO concentration of 20 mM / L, the initial battery capacity is 0.6 Ah / L, lower than 0.68 Ah / L in Example 1, and the capacity retention after 150 cycles is 85.49%, lower than the 100% capacity retention after 400 cycles in Example 1. Both its battery capacity and overall capacity are lower than the DQA-PTO and 4,4'-AZPY synergistic system of this application. The flow battery of this application exhibits excellent cycle stability and electrochemical performance, making it an excellent flow battery.

[0070] The above-described embodiments are merely illustrative of several feasible implementations of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention, nor are the embodiments 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. All equivalent implementations or changes that do not depart from the present invention should be included in the technology of the present invention.

Claims

1. An aqueous redox flow battery, comprising a positive electrode electrolyte, a separator, and a negative electrode electrolyte, characterized in that: The active material of the positive electrode electrolyte is 4,4'-azopyridine, and the active material of the negative electrode electrolyte is 2,7-bis(quaternized acetamyl)pyrene-4,5,9,10-tetraone.

2. The aqueous redox flow battery according to claim 1, characterized in that, The active material of the negative electrode electrolyte is prepared by the following steps: Step 1: Dissolve pyrene in a mixed solvent of dichloromethane and acetonitrile, add sodium periodate, water and ruthenium trichloride hydrate in sequence, stir and react at 30-50°C, and separate pyrene-4,5,9,10-tetraone. Step 2: Add pyrene-4,5,9,10-tetraone to a mixed solution of concentrated sulfuric acid and fuming nitric acid, stir the reaction at 100-120°C, precipitate in deionized water, filter to collect the solid and dry to obtain 2,7-dinitro-pyrene-4,5,9,10-tetraone. Step 3: 2,7-dinitro-pyrene-4,5,9,10-tetraone, sodium hydroxide, and sodium dithionite were added to deionized water and reacted with stirring at 40–60°C. The mixture was then precipitated in a saturated ammonium chloride solution, filtered, washed with deionized water, and the solid was collected and dried. The dried solid was then added to anhydrous methanol with dichlorodicyanoquinone and reacted with stirring at 30–40°C. The mixture was then precipitated in ethyl acetate, filtered, washed with ethyl acetate, and the solid was collected and dried to obtain 2,7-diamino-pyrene-4,5,9,10-tetraone. Step 4: Dissolve 2,7-diamino-pyrene-4,5,9,10-tetraone in DMF, add chloroacetyl chloride, stir and react at 30-40°C, precipitate in water, filter and collect the solid to obtain 2,7-bis(chloroacetamyl)pyrene-4,5,9,10-tetraone; Step 5: Dissolve 2,7-bis(chloroacetamyl)pyrene-4,5,9,10-tetraone in DMF, add trimethylamine ethanol solution, stir and react at 40-50℃, precipitate in acetone, collect the solid, and separate to obtain 2,7-bis(quaternized acetamyl)pyrene-4,5,9,10-tetraone.

3. The aqueous redox flow battery according to claim 2, characterized in that: In step one, the equivalent ratio of pyrene, sodium periodate, and ruthenium trichloride hydrate is 1:0.1-0.2:6-10.

4. The aqueous redox flow battery according to claim 2, characterized in that: In step three, the equivalent ratio of 2,7-dinitro-pyrene-4,5,9,10-tetraone, sodium hydroxide, sodium dithionite, and dichlorodicyanoquinone is 1:300~400:40~50:10~20.

5. An aqueous redox flow battery according to claim 2, characterized in that: In step four, the equivalent ratio of 2,7-diamino-pyrene-4,5,9,10-tetraone and chloroacetyl chloride is 1:2 to 3.

6. The aqueous redox flow battery according to claim 2, characterized in that: In step five, the equivalent ratio of 2,7-bis(chloroacetamido)pyrene-4,5,9,10-tetraone to trimethylamine is 1:10 to 15.

7. The aqueous redox flow battery according to claim 1, characterized in that, The active material of the positive electrode electrolyte is prepared by dissolving 4-p-aminopyridine in deionized water, adding sodium hypochlorite solution dropwise at -20 to -5°C and stirring the reaction, and then separating and drying to obtain 4,4'-azopyridine.

8. The aqueous redox flow battery according to claim 7, characterized in that: The equivalent ratio of 4-p-aminopyridine to sodium hypochlorite is 1:5 to 8.

9. An aqueous redox flow battery according to any one of claims 1 to 8, characterized in that: The concentration of active material in the positive electrode electrolyte is 0.06~0.6 mol / L; the concentration of active material in the negative electrode electrolyte is 0.02~0.2 mol / L.

10. An aqueous redox flow battery according to claim 9, characterized in that: The diaphragm is an MTCP-50 AEM exchange membrane.

Images