An intramolecularly hydrogen-bonded anthraquinone derivative, its synthesis method and applications

Abstract

This application discloses an intramolecular hydrogen bond-enhanced anthraquinone derivative, its synthesis method, and its application, relating to the field of electrochemical energy storage. The acetic acid-modified anthraquinone RH-DA or AE-DA is 2,2'-(3-carboxyl-1,8-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid and 2,2'-(1,8-dihydroxy-3-(hydroxymethyl)-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid. Rhein or aloe-emodin is dissolved in NaOH, glyoxylic acid solution and sodium dithionite are added, and after stirring, sodium dithionite is added again. After stirring and cooling to room temperature, hydrogen peroxide solution and HCl solution are added, causing precipitation. After washing with HCl, the precipitate is dried in a vacuum drying oven to obtain a black-green solid RH-DA or a yellow-green solid AE-DA. Its application in alkaline aqueous organic flow batteries is also disclosed.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage technology, specifically to an intramolecular hydrogen bond-enhanced anthraquinone derivative, its synthesis method, and its application. Background Technology

[0002] Due to the intermittent and fluctuating nature of renewable energy sources, the development of large-scale energy storage technology is urgently needed. Aqueous organic flow batteries (AORFBs) have attracted much attention due to their independently tunable energy and power densities. Organic molecules in nature are widely available, structurally flexible and tunable, and can achieve efficient conversion of chemical energy to electrical energy through redox reactions involving electron gain and loss, giving AORFBs both multi-electron transfer capabilities and a broad molecular design space. In recent years, many typical active organic molecules (such as anthraquinones, phenazines, viologen, and ferrocene derivatives) have shown excellent electrochemical performance and application potential, especially economically viable natural organic molecules. Rhein (RH) and aloe-emodin (AE), as anthraquinone compounds extracted from the rhizome of rhubarb, possess multiple biological activities and tumor-bearing properties, but their limited water solubility and molecular structural instability restrict their application in AORFBs. Previous molecular structure modifications have mostly involved… N -or O Alkylation methods graft solubilizing groups onto the anthraquinone skeleton, but such modified derivatives are not stable enough, and the solubilizing side chains are prone to breakage during long cycles.

[0003] Organic materials have shown great potential for development in molecules used in flow batteries, but the water solubility and structural stability of most organic molecules still need to be further improved through reasonable molecular engineering, such as grafting sulfonic acid groups, carboxyl groups, phenolic hydroxyl groups, phosphate groups, polyethylene glycol groups, etc. Summary of the Invention

[0004] Technical problems solved: This application provides an intramolecular hydrogen bond-enhanced anthraquinone derivative, its synthesis method and application. The anthraquinone derivative synthesized by the diacetic acid functionalization strategy is designed and used in high-capacity aqueous organic flow batteries. It can solve the technical problems that are usually involved in the multiple reaction steps and complex subsequent purification process in existing synthesis methods. The water solubility and structural stability of most organic molecules still need to be further improved through reasonable molecular engineering.

[0005] The specific technical solution of this invention is as follows: An intramolecularly hydrogen-bonded anthraquinone derivative, wherein the intramolecularly hydrogen-bonded anthraquinone derivative is acetic acid-modified anthraquinone RH-DA or AE-DA, and the structural formula of the acetic acid-modified anthraquinone RH-DA or AE-DA is as follows: .

[0006] Further, the acetic acid-modified anthraquinone RH-DA or AE-DA is specifically: 2,2'-(3-carboxy-1,8-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid or 2,2'-(1,8-dihydroxy-3-(hydroxymethyl)-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid.

[0007] This application also discloses a method for synthesizing any of the above-mentioned intramolecular hydrogen bond-enhanced anthraquinone derivatives, wherein the intramolecular hydrogen bond-enhanced anthraquinone derivative is acetic acid-modified anthraquinone RH-DA or AE-DA, and the method for synthesizing RH-DA includes the following steps: Step 1: Dissolve 12.5 mmol of rhein in 100 mL of 1.0 M NaOH solution by molar volume ratio. Stir the mixture at room temperature and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm until the solid is completely dissolved. Step 2: Add 13.7 mmol sodium dithionite and 37.5 mmol glyoxylic acid solution, and stir the mixture at room temperature and nitrogen protection for 1 hour at a speed of 500 rpm. Step 3: Add 13.1 mmol of sodium dithionite, and stir the mixture at 80°C and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm. Step 4: After the solution has cooled to room temperature, add 30 mmol of hydrogen peroxide solution and stir the mixture at room temperature for five minutes at 500 rpm. Step 5: Add 2 M HCl solution to precipitate the precipitate. After washing with 0.1 M HCl, the precipitate is dried in a vacuum drying oven at 60°C for 24 hours to obtain a black-green solid RH-DA.

[0008] Furthermore, the method for synthesizing the AE-DA includes the following steps: Step 1: Dissolve 12.5 mmol of aloe-emodin in 100 mL of 1.0 M NaOH solution by molar volume ratio. Stir the mixture at room temperature and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm until the solid is completely dissolved. Step 2: Add 13.7 mmol sodium dithionite and 37.5 mmol glyoxylic acid solution, and stir the mixture at room temperature and nitrogen protection for 1 hour at a speed of 500 rpm. Step 3: Add 13.1 mmol of sodium dithionite, and stir the mixture at 80°C and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm. Step 4: After the solution has cooled to room temperature, add 30 mmol of hydrogen peroxide solution and stir the mixture at room temperature for five minutes at 500 rpm. Step 5: Add 2 M HCl solution to precipitate the precipitate. After washing with 0.1 M HCl, the precipitate is dried in a vacuum drying oven at 60°C for 24 hours to obtain a yellow-green solid AE-DA.

[0009] Furthermore, the synthetic route for the intramolecularly hydrogen-bonded anthraquinone derivative RH-DA is as follows: .

[0010] Furthermore, the synthetic route for the intramolecularly hydrogen-bonded anthraquinone derivative AE-DA is as follows: .

[0011] Furthermore, the mass ratio of rhein to glyoxylic acid is rhein:glyoxylic acid = 3.55:2.775.

[0012] Furthermore, the mass ratio of aloe-emodin to glyoxylic acid is aloe-emodin:glyoxylic acid = 3.38:2.775.

[0013] This application also discloses the application of any of the above-mentioned intramolecularly hydrogen-bonded anthraquinone derivatives in alkaline aqueous flow batteries.

[0014] Furthermore, the aqueous flow battery is an alkaline aqueous organic flow battery.

[0015] Explanation of the principle: This patent functionalizes two anthraquinone compounds extracted from the natural drug rhubarb, successfully synthesizing two anthraquinone derivatives (RH-DA and AE-DA) through a diacetic acid functionalization strategy. Their water solubility (2.62 and 1.75 M) is significantly enhanced, making them ideal materials for alkaline AORFBs. RH-DA and AE-DA possess multiple highly polar hydrophilic groups, unlike traditional... O -or NUnlike other alkylation strategies, the molecular structure optimization methods for RH-DA and AE-DA involve introducing two carboxyl groups linked by inert carbon atoms at the α-hydroxyl side. The steric hindrance effect caused by these two side chains further enhances intramolecular hydrogen bonding, effectively suppressing the anthraquinone dimerization side reaction. Furthermore, the carboxylic acid chains linked by inert carbon atoms avoid the influence of electrophilic reactions and do not detach during long-term electrochemical cycling. Therefore, RH-DA and AE-DA exhibit excellent structural stability. Consequently, AORFBs based on 0.1 M K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA did not show significant capacity decay throughout 3600 cycles, and the AORFB based on 0.5 M K4Fe(CN)6||RH-DA maintained its capacity at 100 mA cm⁻¹. -2 The capacity decay rate at current densities is as low as 0.0008% / cycle or 0.03% / day; furthermore, at 150 mA cm⁻¹... -2 At a current density of 0.5 M, the capacity decay rate of the AORFB of K4Fe(CN)6||RH-DA was only 0.0021% / cycle or 0.155% / day. Through theoretical calculations and a series of spectral analyses before and after cycling, the structural changes of RH-DA during cycling and its intramolecular hydrogen bond interactions were studied. The results show that the RH-DA molecule has excellent structural stability. The acetic acid groups linked by inert carbon atoms not only avoid the influence of electrophilic side reactions and remain stable, but also enhance the intramolecular hydrogen bonding, thereby effectively suppressing the dimerization side reaction during the electrochemical process. The capacity decay of K4Fe(CN)6||RH-DA AORFB mainly comes from the transmembrane phenomenon of potassium ferrocyanide in the positive electrode electrolyte, while the RH-DA molecule itself does not transmembrane. This patent demonstrates the great potential of the diacetic acid functionalization strategy in creating redox-reversible and electrochemically stable organic molecules, laying a technological foundation for the widespread application of large-scale and environmentally friendly energy storage systems.

[0016] The beneficial effects of this invention are: 1. This invention designs an anthraquinone derivative synthesized through a diacetic acid functionalization strategy for use in alkaline aqueous organic flow batteries. Based on the diacetic acid functionalization strategy, two anthraquinone compounds, rhein or aloe-emodin, extracted from the natural drug rhubarb, are functionalized and modified. The water solubility (2.62 and 1.75 M) of the synthesized RH-DA and AE-DA is significantly enhanced, making them an ideal material for AORFBs. 2. The two acetic acid chains of RH-DA and AE-DA are linked by inert carbon atoms, which not only enhances water solubility but also strengthens intramolecular hydrogen bonding. 3. The steric hindrance effect caused by the two introduced side chains will further enhance the intramolecular hydrogen bonding of the molecule, thereby effectively inhibiting the occurrence of anthraquinone dimerization side reactions; 4. The carboxylic acid chain linked by inert carbon atoms can avoid the influence of electrophilic reactions and will not fall off during long-term electrochemical cycling, thereby improving the stability of the molecule and the electrochemical reversibility. 5. No significant capacity decay was observed in the AORFBs of 0.1 M K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA throughout the entire 3600 cycles, while the AORFB of 0.5 M K4Fe(CN)6||RH-DA remained at 150 mA cm⁻¹. -2 The capacity decay rate at current densities is even as low as 0.0008% / cycle or 0.03% / day; at 150 mA cm⁻¹ -2 At a current density of 0.5 M, the capacity decay rate of AORFB for K4Fe(CN)6||RH-DA is only 0.0021% / cycle or 0.155% / day. 6. Through theoretical calculations and a series of spectral analyses before and after cycling, the structural changes of RH-DA during cycling and its intramolecular hydrogen bond interactions were studied. The results showed that the RH-DA molecule has excellent structural stability. The acetic acid group connected by inert carbon atoms not only avoids the influence of electrophilic side reactions and exists stably, but also enhances the intramolecular hydrogen bond interaction, thereby effectively suppressing the dimerization side reaction in the electrochemical process. The capacity decay of K4Fe(CN)6||RH-DA AORFB is mainly due to the transmembrane phenomenon of potassium ferrocyanide in the positive electrode electrolyte, while the RH-DA molecule itself does not cross the membrane. 7. This patent demonstrates the great potential of biomimetic molecular engineering strategies in creating redox-reversible and electrochemically stable organic molecules, laying the technological foundation for the widespread application of large-scale, environmentally friendly energy storage systems. Attached Figure Description

[0017] Figure 1 This is the 1H NMR spectrum of the RH-DA of this invention; Figure 2 This is the 1H NMR spectrum of the AE-DA of this invention; Figure 3 In the diagram, 'a' represents the UV-Vis absorption spectra of RH-DA at different concentrations in 1.0 M KOH, and 'c' represents the UV-Vis absorption spectra of AE-DA at different concentrations in 1.0 M KOH. Figure 3 In the figure, b is the absorbance vs. concentration fitting graph of the RH-DA solution, and d is the absorbance vs. concentration fitting graph of the AE-DA solution. Figure 4The cyclic voltammetry curves of 4.0 mM RH-DA, AE-DA, and K4Fe(CN)6 in 1.0 M KOH solution are shown. Figure 5 This invention relates to 0.1 M K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA. Electrochemical cycling performance graph of AORFBs Figure 5 Figure 'a' shows the rate performance of AORFBs in 0.1 M K4Fe(CN)6||RH-DA at different current densities. Figure 5 Figure b shows the rate performance of AORFBs of K4Fe(CN)6||AE-DA at 0.1 M under different current densities. Figure 5 Cyclic performance of K4Fe(CN)6||RH-DA with c = 0.1 M under constant current and constant current-constant voltage conditions in AORFB; Figure 5 Cyclic performance of K4Fe(CN)6||AE-DA with d=0.1 M under constant current and constant current-constant voltage conditions in AORFB; Figure 6 In Figure 'a', the charge-discharge curves of 0.5 M K4Fe(CN)6||RH-DA AORFB at different current densities are shown. Figure 6 In the figure, b represents the coulombic efficiency, energy efficiency, and discharge capacity corresponding to K4Fe(CN)6||RH-DA AORFB. Figure 6 In this context, c represents the OCV value of K4Fe(CN)6||RH-DA AORFB under different SOCs. Figure 6 In the figure, d represents the polarization and power density curves of K4Fe(CN)6||RH-DA AORFB under different SOCs. Figure 6 In the case of 100 and 150 mA·cm -2 Long-term constant current cycling performance of K4Fe(CN)6||RH-DA AORFB at 0.5 M. Detailed Implementation

[0018] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0019] In this application, rhein and aloe-emodin were purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd., with a purity of 98%. Glyoxylic acid was purchased from Shanghai Mairui Chemical Technology Co., Ltd., with a purity of 98%.

[0020] Example 1: An intramolecularly hydrogen-bonded anthraquinone derivative, wherein the intramolecularly hydrogen-bonded anthraquinone derivative is acetic acid-modified anthraquinone RH-DA or AE-DA, and the structural formula of the acetic acid-modified anthraquinone RH-DA or AE-DA is as follows: ; The acetic acid-modified anthraquinone RH-DA or AE-DA is specifically: 2,2'-(3-carboxy-1,8-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid or 2,2'-(1,8-dihydroxy-3-(hydroxymethyl)-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid.

[0021] The method for synthesizing RH-DA includes the following steps: Step 1: Dissolve 12.5 mmol of rhein in 100 mL of 1.0 M NaOH solution. Stir the mixture at room temperature and under nitrogen protection for 0.5 hours at a stirring speed of 500 rpm until the solid is completely dissolved. Step 2: Add 13.7 mmol sodium dithionite and 37.5 mmol glyoxylic acid solution, and stir the mixture at room temperature and nitrogen protection for 1 hour at a speed of 500 rpm. Step 3: Add 13.1 mmol of sodium dithionite, and stir the mixture at 80°C and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm. Step 4: After the solution cools to room temperature, add 30 mmol of hydrogen peroxide solution; stir the mixture at room temperature for five minutes at 500 rpm. Step 5: Add 2 M HCl solution to precipitate the precipitate. After washing with 0.1 M HCl, the precipitate is dried in a vacuum drying oven at 60°C for 24 hours to obtain a black-green solid RH-DA.

[0022] The mass ratio of rhein to glyoxylic acid is rhein:glyoxylic acid = 3.55:2.775.

[0023] The method for synthesizing AE-DA includes the following steps: Step 1: Dissolve 12.5 mmol of aloe-emodin in 100 mL of 1.0 M NaOH solution. Stir the mixture at room temperature and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm until the solid is completely dissolved. Step 2: Add 13.7 mmol sodium dithionite and 37.5 mmol glyoxylic acid solution, and stir the mixture at room temperature and nitrogen protection for 1 hour at a speed of 500 rpm. Step 3: Add 13.1 mmol of sodium dithionite, and stir the mixture at 80°C and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm. Step 4: After the solution cools to room temperature, add 30 mmol of hydrogen peroxide solution; stir the mixture at room temperature for five minutes at 500 rpm. Step 5: Add 2 M HCl solution to precipitate the precipitate. After washing with 0.1 M HCl, the precipitate is dried in a vacuum drying oven at 60°C for 24 hours to obtain a yellow-green solid AE-DA.

[0024] The mass ratio of aloe-emodin to glyoxylic acid is aloe-emodin:glyoxylic acid = 3.38:2.775.

[0025] The synthetic route for the intramolecular hydrogen-bonded anthraquinone derivative RH-DA is as follows: .

[0026] The synthetic route for the intramolecular hydrogen-bonded anthraquinone derivative AE-DA is as follows: .

[0027] Figure 1 and Figure 2 The images show the 1H NMR spectra of RH-DA and AE-DA.

[0028] The application of two intramolecular hydrogen bond-enhanced anthraquinone derivatives in an aqueous flow battery, wherein the aqueous flow battery is an alkaline aqueous organic flow battery.

[0029] Example 2, Solubility test of RH-DA and AE-DA: Standard concentrations of RH-DA and AE-DA solutions dissolved in 1.0 M KOH solution were prepared using a 10 mL graduated cylinder. The absorbance of these solutions was measured at 0.2 nm intervals within the wavelength range of 250 to 700 nm using a UV-Vis spectrophotometer. Concentration curves of the standard solutions were plotted based on the absorbance at their highest absorption peaks. The saturated solution was prepared by gradually adding RH-DA and AE-DA solids to 1.0 mL of 1.0 M KOH solution and sonicating until a small amount of precipitate appeared. Then, 100 μL of the saturated solution was pipetted and diluted to the appropriate factor using 1.0 M KOH solution. The maximum solubility of the solution was determined by plotting a UV-Vis absorbance versus concentration graph.

[0030] like Figure 3As shown, the solubility of RH-DA and AE-DA in 1.0 M KOH solution was tested by UV-Vis absorption spectroscopy. The solubility of RH-DA and AE-DA in 1.0 M KOH solution was 2.62 and 1.75 M, respectively. The test results verified that the two acetic acid side chains significantly improved the water solubility of anthraquinone molecules. Figure 3 a and Figure 3 In the figure, b represents the UV-Vis absorption spectra of RH-DA and AE-DA at different concentrations in 1.0 M KOH, corresponding to... Figure 3 c and Figure 3 In the figure, d represents the absorbance versus concentration fitting plot of RH-DA and AE-DA solutions.

[0031] Example 3: Based on Example 1, this example tests the electrochemical performance of RH-DA and AE-DA, as follows: Electrochemical parameters were measured using an electrochemical workstation. A three-electrode configuration was used for CV testing, with a 3 mm diameter glassy carbon electrode as the working electrode, a saturated Ag / AgCl electrode as the reference electrode, and a platinum electrode as the counter electrode. The test solutions were 4 mM RH-DA, AE-DA, and 1 M KOH solution of K4Fe(CN)6.

[0032] like Figure 4 As shown, the redox properties of RH-DA, AE-DA, and K4Fe(CN)6 in 1.0 M KOH solution were tested by cyclic voltammetry. Figure 4 Cyclic voltammetry curves of RH-DA, AE-DA, and K4Fe(CN)6 in 1.0 M KOH solution at 4.0 mM, and oxygen reduction potentials of RH-DA, AE-DA, and K4Fe(CN)6 (…). vs. The Ag / AgCl electrodes were -0.74, -0.75, and 0.29 V, respectively.

[0033] Flow battery performance testing: 1. By using different charging states at 100 mA·cm -2 The battery was charged at a certain current density and allowed to rest for 30 seconds. The OCV was recorded, and the SOC curve was measured. When the battery voltage was maintained at 1.5V, it was charged to 100% SOC. The polarization curves were obtained using LSV at 20%, 50%, and 100% SOC at 100 mV·s. -1 The scan rate was measured.

[0034] 2. For the constant current cycling test of 0.1 M RH-DA and AE-DA, the negative electrode electrolyte was 0.1 M RH-DA or AE-DA dissolved in 5 mL of 1.0 M KOH solution, and the positive electrode electrolyte was 0.2 M K4Fe(CN)6 dissolved in 15.0 mL of 1.0 M KOH solution. The constant current cycling was performed at a rate of 100 mA·cm⁻¹ between 1.5 V and 0.4 V. -2 The constant current was used to conduct cyclic testing of the flow battery.

[0035] 3. For the constant current-constant voltage charge-discharge test of 0.1 M RH-DA and AE-DA in 1.0 M KOH solution, at a current density of 100 mA·cm⁻¹ -2 Charge to 1.5V, then maintain that voltage until the current density drops to 5 mA·cm⁻¹. -2 It was then discharged to 0.4V and maintained at that voltage until the current density dropped to 5 mA·cm⁻¹. -2 .

[0036] 4. For the constant current cycling test of 0.5 M RH-DA, the negative electrode electrolyte was 0.5 M RH-DA dissolved in 5 mL of 1.0 M KOH solution, and the positive electrode electrolyte was 0.4 M K4Fe(CN)6 dissolved in 80.0 mL of 1.0 M KOH solution. The constant current cycling was performed at a voltage between 1.5 V and 0.4 V at a rate of 100 or 150 mA·cm⁻¹. -2 The constant current was used to conduct cyclic testing of the flow battery.

[0037] Performance testing of flow batteries based on RH-DA or AE-DA: a. Constant current charge-discharge cycling of AORFBs with low concentrations of RH-DA and AE-DA negative electrolytes, K4Fe(CN)6 positive electrolyte, and sPEEK membrane was studied. The negative electrolyte was 0.1 M RH-DA or AE-DA dissolved in 5 mL of 1.0 M KOH solution, and the positive electrolyte was 0.2 M K4Fe(CN)6 dissolved in 15.0 mL of 1.0 M KOH solution. The cycling temperature range was 20 to 150 mA·cm⁻¹. -2 Rate performance was tested within the current density range. Figure 5 a and Figure 5 (b) At 20 and 50 mA·cm -2 At that time, the AORFBs capacities of K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA were 4.85 and 4.51 Ah·L, respectively. -1 And 4.52 and 4.22 Ah·L -1The capacity utilization rates were 92.2% and 85.7%, and 85.9% and 80.2%, respectively. As the current density increased, the energy density and capacity utilization rate of the battery decreased. When the current density reached 150 mA·cm⁻¹... -2 At that time, the capacity utilization rates of AORFBs of 0.1 M K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA were 72.1% and 61.9%, respectively, with corresponding energy efficiency values ​​of 69.8 and 72.8%.

[0038] b. At 100 mA cm -2 At current density, the battery was subjected to 1600 cycles in constant current mode, such as... Figure 5 c and Figure 5 As shown in Figure d, the discharge capacity of AORFBs of K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA remained essentially unchanged, demonstrating good capacity retention. Subsequently, 1600 cycles of constant current-voltage constant voltage charge-discharge mode were performed at the same current density. During charging, the potential was maintained at 1.5V until the current density dropped to 5 mA·cm⁻¹. -2 Similarly, the potential remained at 0.4 V during discharge until the current density dropped to 5 mA·cm⁻¹. -2 These conditions can induce near 100% redox activity in organic active molecules, thus aiding in the study of their electrochemical stability during complete charge-discharge processes. After 1600 cycles, the capacity of AORFBs of K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA showed no significant decay.

[0039] like Figure 5 The diagram shows the electrochemical performance of AORFBs of 0.1 M K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA. Figure 5 a and Figure 5 In the figure, b represents the rate performance of AORFBs for K4Fe(CN)6||RH-DA and K4Fe(CN)6||AE-DA at 0.1 M under different current densities. Figure 5 Cyclic performance of K4Fe(CN)6||RH-DA with c = 0.1 M under constant current and constant current transverse voltage conditions in AORFB. Figure 5 Cyclic performance of K4Fe(CN)6||AE-DA with d=0.1 M for constant current and constant current transverse voltage at AORFB.

[0040] Figure 6 In Figure 'a', the charge-discharge curve of AORFB for 0.5 M K₄Fe(CN)₆||AE-DA at the same current density is shown. Figure 6 In the figure, b represents the corresponding coulombic efficiency, energy efficiency, and discharge capacity. Figure 6 In this context, c represents the OCV value of K4Fe(CN)6||RH-DA AORFB under different SOCs. Figure 6 In the figure, d represents the polarization curve and power density curve of AORFB under different SOCs. Figure 6 In the case of 100 and 150 mA·cm -2 Long-term constant current cycling performance of 0.5MK4Fe(CN)6||RH-DA AORFB.

[0041] like Figure 6 As shown, considering practical applications, this patent also investigated the electrochemical performance of AORFB in 0.5 M K4Fe(CN)6||RH-DA. For example... Figure 6 a and Figure 6 As shown in Figure b, at 20, 50, 80, 100, 120, and 150 mA·cm -2 The rate performance of high-concentration K4Fe(CN)6||RH-DA in AORFB was measured at current densities ranging from 20 to 150 mA·cm⁻¹. -2 The capacity decreased from 26.4 Ah·L to 24.0 Ah·L. -1 The energy density decreased from 88.9% to 70.5%. This result highlights the K4Fe(CN)6||RH-DA The excellent rate performance of AORFB verifies its enormous application potential in high-power energy storage scenarios. For example... Figure 6 As shown in Figure c, high concentrations of K4Fe(CN)6||RH-DA were recorded. AORFB OCV values ​​from 10% to 100% SOC. At 50% SOC, the open-circuit voltage is 1.01V. For example... Figure 6 As shown in Figure d, the polarization curve and power density of 0.5 M K4Fe(CN)6||RH-DA AORFB were obtained by linear sweep voltammetry. At 100% SOC, the peak power density was 220 mW·cm⁻¹. -2 .

[0042] like Figure 6 As shown in Figure e, at 100 and 150 mA·cm -2 The constant-current cycling stability of 0.5 M high-concentration K4Fe(CN)6||RH-DA AORFB was tested at a current density of [value missing]. During 3000 cycles (60 days), the capacity finally stabilized at 24.99 and 22.71 Ah·L. -1 The corresponding capacity decay rates are 0.0008% / cycle or 0.03% / day and 0.0021% / cycle or 0.155% / day, respectively.

[0043] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. An anthraquinone derivative with enhanced intramolecular hydrogen bonding, characterized in that, The intramolecular hydrogen bond-enhanced anthraquinone derivative is acetic acid-modified anthraquinone RH-DA or AE-DA, and the structural formula of the acetic acid-modified anthraquinone RH-DA or AE-DA is as follows: 。 2. The intramolecular hydrogen-bonded enhanced anthraquinone derivative according to claim 1, characterized in that, The acetic acid-modified anthraquinone RH-DA or AE-DA is specifically: 2,2'-(3-carboxy-1,8-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid or 2,2'-(1,8-dihydroxy-3-(hydroxymethyl)-9,10-dioxo-9,10-dihydroanthracene-2,7-diyl)diacetic acid.

3. A method for synthesizing the intramolecular hydrogen-bonded enhanced anthraquinone derivative as described in claim 1, characterized in that, The intramolecular hydrogen-bonded enhanced anthraquinone derivative is acetic acid-modified anthraquinone RH-DA or AE-DA, wherein the synthesis method of RH-DA is specified. Includes the following steps: Step 1: Dissolve 12.5 mmol of rhein in 100 mL of 1.0 M NaOH solution by molar volume ratio. Stir the mixture at room temperature and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm until the solid is completely dissolved. Step 2: Add 13.7 mmol sodium dithionite and 37.5 mmol glyoxylic acid solution, and stir the mixture at room temperature and nitrogen protection for 1 hour at a speed of 500 rpm. Step 3: Add 13.1 mmol of sodium dithionite, and stir the mixture at 80°C and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm. Step 4: After the solution has cooled to room temperature, add 30 mmol of hydrogen peroxide solution and stir the mixture at room temperature for five minutes at 500 rpm. Step 5: Add 2 M HCl solution to precipitate the precipitate. After washing with 0.1 M HCl, the precipitate is dried in a vacuum drying oven at 60°C for 24 hours to obtain a black-green solid RH-DA.

4. The method for synthesizing intramolecular hydrogen-bonded anthraquinone derivatives according to claim 3, characterized in that, The method for synthesizing AE-DA includes the following steps: Step 1: Dissolve 12.5 mmol of aloe-emodin in 100 mL of 1.0 M NaOH solution by molar volume ratio. Stir the mixture at room temperature and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm until the solid is completely dissolved. Step 2: Add 13.7 mmol sodium dithionite and 37.5 mmol glyoxylic acid solution, and stir the mixture at room temperature and nitrogen protection for 1 hour at a speed of 500 rpm. Step 3: Add 13.1 mmol of sodium dithionite, and stir the mixture at 80°C and nitrogen protection for 0.5 hours at a stirring speed of 500 rpm. Step 4: After the solution has cooled to room temperature, add 30 mmol of hydrogen peroxide solution and stir the mixture at room temperature for five minutes at 500 rpm. Step 5: Add 2 M HCl solution to precipitate the precipitate. After washing with 0.1 M HCl, the precipitate is dried in a vacuum drying oven at 60°C for 24 hours to obtain a yellow-green solid AE-DA.

5. The method for synthesizing intramolecular hydrogen-bonded anthraquinone derivatives according to claim 3, characterized in that, The synthetic route for the intramolecular hydrogen-bonded anthraquinone derivative RH-DA is as follows: 。 6. The method for synthesizing the intramolecular hydrogen-bonded anthraquinone derivative according to claim 4, characterized in that, The synthetic route for the intramolecular hydrogen-bonded anthraquinone derivative AE-DA is as follows: 。 7. The method for synthesizing intramolecular hydrogen-bonded anthraquinone derivatives according to claim 3, characterized in that, The mass ratio of rhein to glyoxylic acid is rhein:glyoxylic acid = 3.55:2.

775.

8. The method for synthesizing intramolecular hydrogen-bonded anthraquinone derivatives according to claim 4, characterized in that, The mass ratio of aloe-emodin to glyoxylic acid is aloe-emodin:glyoxylic acid = 3.38:2.

775.

9. The application of an intramolecular hydrogen-bonded anthraquinone derivative as described in claim 1 or 2 in an aqueous flow battery.

10. The application according to claim 9, characterized in that, The aqueous flow battery is an alkaline aqueous organic flow battery.

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