A method for hydrothermal synthesis of naphthalimide derivatives

Abstract

The application discloses a hydrothermal synthesis method of a naphthalimide derivative, and has the advantages of simplicity, low cost, high yield, and fast synthesis speed. The naphthalimide molecule has conjugation, high rigidity, and a large molecular volume; the strong conjugation makes the band gap of the naphthalimide molecule narrower, enables fast transfer of electrons, and further realizes stable double electron transfer; and the large molecular volume avoids the penetration of the anode electrolyte through the ion exchange membrane in the charge and discharge cycle. The application increases the water solubility of the molecule through quaternary ammonium salt and other water-soluble modifications; compared with the previous research, the water-soluble groups are increased from two to four or more, further increasing the water solubility of the molecule; and the increase of the water-soluble groups also increases the molecular size, so that the anode electrolyte for a liquid flow battery has stable cycle performance in the cycle process.

Description

[0001] This invention is a divisional application of the invention patent with patent application number 2023101824578, application date 2023-02-28, and invention title "A class of naphthaleneimide derivatives and their preparation method and application in flow batteries". Technical Field

[0002] This invention belongs to the field of flow battery electrode material technology, specifically relating to a hydrothermal synthesis method for a class of naphthalimide derivatives. Background Technology

[0003] Among existing energy storage technologies, flow batteries balance energy and power, fundamentally solving the safety issues inherent in energy storage. Flow batteries also offer advantages such as long lifespan, capacity increases requiring only the addition of electrolyte, high-power discharge capabilities, and short charge-discharge cycles. Currently, commercially available flow batteries, such as vanadium redox batteries and zinc-bromine batteries, use corrosive and expensive electrolytes, severely limiting their large-scale application. Within flow batteries, neutral aqueous organic redox batteries have attracted widespread attention due to their large capacity, high safety, low cost, environmental friendliness, and the ability to adjust organic molecules to achieve high (cathode) or low (anode) redox potentials.

[0004] Electrolyte materials, as a crucial component of flow batteries, play a vital role in the battery's capacity and stability. For neutral aqueous organic flow batteries, commonly used anode electrolytes include viologen, anthraquinone, and their derivatives, while common cathode electrolytes include (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) and ferrocene. However, viologen molecules have poor conjugation, generally only achieving single-electron storage. Some research groups have incorporated conjugated groups such as furan, thiophene, and phenyl into bipyridine to enhance the overall conjugation of the molecule and reduce the potential difference between the first and second reduction potentials. While modified viologen molecules show improved stability, their solubility decreases. Therefore, developing new substrates and modifying them as active materials is of great significance for the research of neutral aqueous flow batteries. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a class of naphthalimide derivatives, their preparation method and their application in flow batteries, so as to solve the technical problems of weak conjugation and low two-electron storage stability of existing anolyte molecules (such as viologen).

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a class of naphthalimide derivatives, the structural formula of which is as follows:

[0008]

[0009] Where R is any one of a, b, c, d, e, and f, and:

[0010]

[0011] n = 0 or 1, m = 1 to 10.

[0012] This invention also discloses a method for preparing the above-mentioned naphthalimide derivative, comprising:

[0013] Precursor A and XR were dissolved in a solvent and reacted at 100–110 °C for 40–50 h to obtain a reaction solution. After cooling the reaction solution, the product was filtered, separated, washed, and dried to obtain the naphthalimide derivative.

[0014] The structural formula of precursor A is as follows:

[0015]

[0016] n = 0 or 1;

[0017] In XR, X is Cl, Br, or I;

[0018] R is any one of a, b, c, d, e, and f, where:

[0019]

[0020] Preferably, the molar ratio of precursor A to XR is 1:3.

[0021] Preferably, the solvent is acetonitrile, N,N-dimethylformamide, tetrahydrofuran, toluene, or water.

[0022] Preferably, when X is Cl, the reaction product is sequentially filtered, washed, and dried to obtain the target product.

[0023] Preferably, when X is Br or I, the reaction product is dissolved in deionized water and anion exchanged with a chloride ion exchange resin to convert it into chloride ions, and then rotary evaporated to obtain the target product.

[0024] Preferably, the synthesis method of precursor A is as follows:

[0025] Compound B was dissolved in an organic solvent under an argon atmosphere and heated to 90°C. Then, 2-dimethylaminopropylamine or 3-dimethylaminopropylamine was added, and the reaction temperature was raised to 100-110°C. The reaction was carried out for 23-25 ​​hours, and the mixture was concentrated under reduced pressure to obtain a crude product. The crude product was recrystallized to obtain precursor A.

[0026] The structural formula of compound B is as follows:

[0027]

[0028] Preferably, the molar ratio of compound B to 2-dimethylaminopropylamine or 3-dimethylaminopropylamine is 1:6.5.

[0029] The present invention also discloses the application of the above-mentioned naphthalimide derivative in the preparation of flow battery electrode materials.

[0030] Preferably, the naphthalimide derivative is used as the anode electrolyte material in an aqueous organic redox flow battery.

[0031] This invention discloses a hydrothermal synthesis method for a naphthimide derivative, comprising the following steps:

[0032] Precursor A and 3-chloro-1-propanol were reacted in water at 120°C for 24 h. After the reaction was completed, the product, ethanol and acetone were added to the aqueous solution obtained from the reaction in a volume ratio of 1:10:2. The product was precipitated, filtered, washed and dried to obtain the naphthalimide derivative.

[0033] The structural formula of precursor A is as follows:

[0034]

[0035] The structural formula of the obtained naphthalimide derivative is as follows:

[0036]

[0037] Preferably, precursor A is prepared by the following method:

[0038] Compound B was dissolved in toluene, and 3-dimethylaminopropylamine was added. The mixture was reacted at 120°C for 24 hours. After the reaction was completed, the mixture was filtered to obtain a golden yellow solid. The golden yellow solid was washed and dried to obtain precursor A.

[0039] The structural formula of compound B is as follows:

[0040]

[0041] More preferably, the molar ratio of compound B to 3-dimethylaminopropylamine is 1:5.

[0042] More preferably, the washing and drying treatment of the golden yellow solid involves washing the golden yellow solid with ethanol three times and then vacuum drying it.

[0043] Preferably, the product is filtered, washed, and dried by washing it three times with acetone and then vacuum drying to obtain a grayish-white powder, i.e., the naphthalimide derivative.

[0044] This invention also discloses a hydrothermal synthesis method for naphthalimide derivatives, comprising the following steps:

[0045] Precursor A and 3-chloropropyl-3-methylammonium chloride were reacted in water at 120°C for 24 h. After the reaction was completed, the product, ethanol and acetone were added to the aqueous solution obtained from the reaction in a volume ratio of 1:10:2. The product was precipitated, filtered, washed and dried to obtain the naphthalimide derivative.

[0046] The structural formula of precursor A is as follows:

[0047]

[0048] The structural formula of the obtained naphthalimide derivative is as follows:

[0049]

[0050] Preferably, precursor A is prepared by the following method:

[0051] Compound B was dissolved in toluene, and 3-dimethylaminopropylamine was added. The mixture was reacted at 120°C for 24 hours. After the reaction was completed, the mixture was filtered to obtain a golden yellow solid. The golden yellow solid was washed and dried to obtain precursor A.

[0052] The structural formula of compound B is as follows:

[0053]

[0054] More preferably, the molar ratio of compound B to 3-dimethylaminopropylamine is 1:5.

[0055] More preferably, the washing and drying treatment of the golden yellow solid involves washing the golden yellow solid with ethanol three times and then vacuum drying it.

[0056] Preferably, the product is filtered, washed, and dried by washing it three times with acetone and then vacuum drying to obtain a grayish-white powder, i.e., the naphthalimide derivative.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] This invention discloses a class of naphthalimide derivatives. Compared to viologen molecules, naphthalimide molecules exhibit stronger conjugation, greater rigidity, and larger molecular volume. Strong conjugation results in a narrower band gap for naphthalimide molecules, enabling rapid electron transfer and thus stable two-electron transfer. The large molecular volume prevents the anolyte from penetrating the ion exchange membrane during charge-discharge cycles. This invention increases the water solubility of the molecule through quaternary ammonium salts and other water-soluble modifications. Compared to previous studies, the number of water-soluble groups has increased from two to four or more, further enhancing molecular water solubility. Furthermore, the increase in water-soluble groups also increases the molecular size. Therefore, the naphthalimide derivatives disclosed in this invention can solve the technical problems of weak conjugation and low two-electron storage stability in existing anolyte molecules (such as viologen).

[0059] This invention also discloses a method for preparing naphthalimide derivatives. This method requires only two reaction steps: using precursors A and RX as raw materials, the reaction is carried out under argon atmosphere in the solvent at 100–110°C for 40–50 h to generate naphthalimide-based derivatives. After a series of operations including filtration, washing, and drying, the target product is obtained. Ionizing the terminal N atom to introduce a hydrophilic group can further increase the molecular size and improve the water solubility of the molecule. This method is low-cost, high-yield, and fast. These derivatives can be used as the anolyte in neutral aqueous organic flow batteries.

[0060] The present invention also provides a hydrothermal synthesis method for naphthalimide derivatives to replace the solvothermal method. This method is simple to operate, does not require inert gas conditions, has mild reaction conditions, low cost, and simple product purification treatment, which only requires filtration. It has high yield and greatly shortens the overall reaction time, making it suitable for industrial-scale production.

[0061] This invention also provides applications of the aforementioned naphthalimide derivatives, utilizing their high solubility in water, large output voltage within the water electrolysis range, good cyclic voltammetry curves, reversible redox peaks, and strong two-electron stability exhibited in electrochemical tests. These characteristics make them suitable for high-capacity, high-power, and long-life neutral aqueous organic flow batteries, ideal for large-scale energy storage. This invention is of great significance for the development of naphthalimide derivatives in neutral aqueous flow batteries. This invention uses a synthesized naphthalimide derivative as the anode electrolyte, ionized ferrocene (FcNCl) or TEMPO as the cathode electrolyte, and all electrolyte materials are dissolved in 2M NaCl to increase the conductivity of the solution. A DSV membrane is used as the anion exchange membrane to form a neutral aqueous organic flow battery with two-electron storage. Attached Figure Description

[0062] Figure 1This is the CV curve diagram in Embodiment 1 of the present invention.

[0063] Figure 2 The full-cell CV curve of the battery installed in Embodiment 1 of the present invention.

[0064] Figure 3 This is an electrochemical test diagram of the battery installed in Example 1 of this invention with 0.1M siol-NDI / 0.1M MiAcNH-TEMPO.

[0065] Figure 4 This is an electrochemical test diagram of the 0.1M siol-NDI / 0.1M FcNCl battery installed in Example 1 of the present invention. Detailed Implementation

[0066] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0067] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0068] The present invention will now be described in further detail with reference to the accompanying drawings:

[0069] This invention discloses a class of naphthalimide derivatives, the chemical reaction formula of which is as follows:

[0070]

[0071] Wherein, the substituent R can be any one of a, b, c, d, e, f.

[0072] in,

[0073]

[0074] The value of n is 0 or 1, and the value of m is 1-10.

[0075] I. Synthesis Examples

[0076] Example 1: Synthesis of Siol-NDI

[0077] Let n = 1, m = 1, and R = a. Then the structure of precursor A is as follows:

[0078]

[0079] Precursor A and 3-bromo-1-propanol were reacted in the organic solvent N,N-dimethylformamide at 100–110 °C for 40–50 h to obtain a reaction solution. After cooling, the solution was filtered to separate it from the product. The product was washed with 3 × 10 ml of cold DMF, 3 × 10 ml of acetone, and 3 × 10 ml of diethyl ether, and then dried under vacuum to obtain Siol-NDI with Br ions as the anion. The molar ratio of precursor A to 3-bromo-1-propanol was 1:3. The product was dissolved in deionized water and subjected to anion exchange with a chloride ion exchange resin to convert it to chloride ions. The resulting product was then rotary evaporated to obtain a milky white product. This product was named Siol-NDI, with a yield of 82%.

[0080] Method 2: In a high-pressure reactor, precursor A and 3-chloro-1-propanol were reacted in water at 120°C for 24 hours. After the reaction was complete, ethanol and acetone were added sequentially to the resulting aqueous solution at a volume ratio of 1:10:2 (product:ethanol:acetone), precipitating a pure product. The product was filtered, washed three times with acetone, and vacuum dried to obtain a grayish-white Siol-NDI powder with a yield of 91%.

[0081] The structure of siol-NDI is shown below:

[0082]

[0083] The precursor A is obtained as follows:

[0084] Compound B was dissolved in toluene under argon atmosphere, and then heated to 90°C to accelerate the dissolution of compound B. 3-Dimethylaminopropylamine was then added dropwise. The reaction was carried out at 100–110°C for 23–25 h. After the reaction was complete, the crude product was concentrated under reduced pressure. After the reaction was complete, the crude product was concentrated under reduced pressure to remove some toluene until solid material precipitated on the container wall. An appropriate amount of ethanol was added to the concentrated solution, and recrystallization followed by filtration yielded a golden-yellow solid. The golden-yellow solid was washed with ethanol and dried under vacuum. The molar ratio of compound B to 3-dimethylaminopropylamine was 1:6.5.

[0085] Method 2: In a reaction vessel, compound B was dissolved in toluene, and 3-dimethylaminopropylamine was added. The mixture was heated to 120°C and reacted for 24 hours. After the reaction was complete, the mixture was filtered, and the golden-yellow solid was washed three times with ethanol and then dried under vacuum. The molar ratio of compound B to 3-dimethylaminopropylamine was 1:5.

[0086] The chemical reaction equation for precursor A is:

[0087]

[0088] The structural formula of compound B is shown below:

[0089]

[0090] Example 2: Synthesis of NPr-NDI

[0091] Let n = 1, m = 1, and R = b. Then the structure of precursor A is as follows:

[0092]

[0093] Precursor A and 3-bromopropyl-3-methylammonium bromide were reacted in the organic solvent N,N-dimethylformamide at 100–110 °C for 40–50 h to obtain a reaction solution. After cooling, the solution was filtered to separate the product from the precursor. The product was washed with 3 × 10 mL of cold DMF, 3 × 10 mL of acetone, and 3 × 10 mL of diethyl ether, and then dried under vacuum to obtain NPr-NDI with Br ions as the anion. The equivalent ratio of precursor A to 3-bromopropyl-3-methylammonium bromide was 1:3. The product was dissolved in deionized water and subjected to anion exchange with a chloride ion exchange resin to convert it to chloride ions. The resulting product was then rotary evaporated to obtain a white product. This product was named NPr-NDI, with a yield of 80%.

[0094] Method 2: In a high-pressure reactor, precursor A and 3-chloropropyl-3-methylammonium chloride were reacted in water at 120°C for 24 hours. After the reaction was complete, ethanol and acetone were added sequentially to the resulting aqueous solution at a volume ratio of 1:10:2 (product:ethanol:acetone), precipitating a pure product. The product was filtered, washed three times with acetone, and vacuum dried to obtain a grayish-white powder of Npr-NDI, with a yield of 93%.

[0095] The NPr-NDI structure is shown below:

[0096]

[0097] The precursor A is obtained as follows:

[0098] Compound B was dissolved in toluene under argon atmosphere, and then heated to 90°C to accelerate the dissolution of compound B. 3-Dimethylaminopropylamine was then added dropwise. The reaction was carried out at 100–110°C for 23–25 hours. After the reaction was complete, the crude product was concentrated under reduced pressure. After the reaction was complete, the crude product was concentrated under reduced pressure to remove some toluene until solid material precipitated on the container wall. An appropriate amount of ethanol was added to the concentrated solution, and recrystallization followed by filtration yielded a golden-yellow solid. The golden-yellow solid was washed with ethanol and dried under vacuum. The equivalence ratio of compound B to 3-dimethylaminopropylamine was 1:6.5.

[0099] Method 2: In a reaction vessel, compound B was dissolved in toluene, and 3-dimethylaminopropylamine was added. The mixture was heated to 120°C and reacted for 24 hours. After the reaction was complete, the mixture was filtered, and the golden-yellow solid was washed three times with ethanol and then dried under vacuum. The molar ratio of compound B to 3-dimethylaminopropylamine was 1:5.

[0100] The chemical reaction equation for precursor A is:

[0101]

[0102] The structural formula of compound B is shown below:

[0103]

[0104] Example 3 Synthesis of NDI-SO3

[0105] Let n = 1, m = 1, and R = c. Then the structure of precursor A is as follows:

[0106]

[0107] Precursor A and 1,3-propanesulfonic acid lactone were reacted in the organic solvent N,N-dimethylformamide at 150–160 °C for 20–30 h to obtain a reaction solution. After cooling, the solution was filtered to separate it from the product. The product was washed with 3 × 10 ml of cold DMF, 3 × 10 ml of acetone, and 3 × 10 ml of diethyl ether, and then dried under vacuum to obtain NDI-SO3. The equivalent ratio of precursor A to 1,3-propanesulfonic acid lactone was 1:3. This product was named NDI-SO3 with a yield of 95%. The structural formula of NDI-SO3 is shown below:

[0108]

[0109] The precursor A is obtained as follows:

[0110] Compound B was dissolved in toluene under argon atmosphere, and then heated to 90°C to accelerate the dissolution of compound B. 3-Dimethylaminopropylamine was then added dropwise. The reaction was carried out at 100–110°C for 23–25 h. After the reaction was complete, the crude product was concentrated under reduced pressure. After the reaction was complete, the crude product was concentrated under reduced pressure to remove some toluene until solid material precipitated on the container wall. An appropriate amount of ethanol was added to the concentrated solution, and recrystallization followed by filtration yielded a golden-yellow solid. The golden-yellow solid was washed with ethanol and dried under vacuum. The equivalence ratio of compound B to 3-dimethylaminopropylamine was 1:6.5.

[0111] Method 2: In a reaction vessel, compound B was dissolved in toluene, and 3-dimethylaminopropylamine was added. The mixture was heated to 120°C and reacted for 24 hours. After the reaction was complete, the mixture was filtered, and the golden-yellow solid was washed three times with ethanol and then dried under vacuum. The molar ratio of compound B to 3-dimethylaminopropylamine was 1:5.

[0112] The chemical reaction equation for precursor A is:

[0113]

[0114] The structural formula of compound B is shown below:

[0115]

[0116] The specific 1H NMR data for the naphthalimide derivative prepared in Example 1 of this invention are as follows:

[0117] 1H NMR(400MHz,D2O)δ8.64(s,4H),4.23(t,J=7.0Hz,4H),3.67(t,J=5.9Hz,4H),3.54–3.48( m,4H),3.44–3.38(m,4H),3.10(s,12H),2.29–2.21(m,4H),2.00(dd,J=10.7,6.1Hz,4H).

[0118] This proves that the above process successfully synthesized the compound.

[0119] II. Application of the naphthalimide derivative prepared in this invention as an anode electrolyte material

[0120] The neutral aqueous organic flow battery electrode material prepared using the naphthalimide derivative NDI-OH obtained in Example 1 can be prepared through the following steps:

[0121] Step 1: Assemble the core fixture

[0122] The neutral aqueous organic redox flow battery used in the test is a single-cell structure. The positive electrode plate, positive insulating plate, positive conductive plate, positive flow frame, positive graphite felt, positive gasket, anion exchange membrane, negative gasket, negative graphite felt, negative flow frame, negative conductive plate, negative insulating plate, and negative electrode plate are sequentially fixed with bolts. External pipes are then connected, and the bolts are checked for looseness; if loose, they are tightened again. Before testing, a sealing and pressure test should be performed. Two storage bottles and a peristaltic pump are connected to the above fixture. After 2 hours of circulation, if there is no leakage or change in liquid volume, it can be stored for later use. If any of the above defects occur, readjustment is required.

[0123] Step 2: Electrode material preparation

[0124] Prepare a sufficient amount of 2M NaCl solution in a volumetric flask. The cathode electrolyte is a methylimidazolium-functionalized (2,2,6,6-tetramethylpiperidin-1-yl)oxy solution with the chemical formula C2. 15 H 26 N4O2, abbreviated as MiAcNH-TEMPO, or dicyclopentadiene iron solution, has the chemical formula Fe(C5H5)2, abbreviated as ferrocene (FcNCl).

[0125] (1) Preparation of 0.1M siol-NDI / 0.1M MiAcNH-TEMPO neutral aqueous organic flow battery

[0126] Dissolve 390 mg of Siol-NDI and 495 mg of MiAcNH-TEMPO in 6 mL and 15 mL of 2M NaCl solution, respectively, and stir or sonicate until completely dissolved. The concentration of both in the NaCl solution is 0.1 M. The volume ratio of the resulting mixture is 1:2.5 to ensure complete charge and discharge of Siol-NDI. Bubble the mixture with argon gas for 10 minutes. The derivatives Siol-NDI and MiAcNH-TEMPO are used as the anolyte and catholyte of the battery, respectively, and are referred to as 0.1 M Siol-NDI / 0.1 M MiAcNH-TEMPO.

[0127] (2) Preparation of 0.1M Siol-NDI / 0.1M FcNCl neutral aqueous organic flow battery

[0128] 390 mg of Siol-NDI and 440 mg of FcNCl were dissolved in 6 mL and 15 mL of 2M NaCl solution, respectively, and stirred or sonicated until completely dissolved. The concentration of both in the NaCl solution was 0.1 M. The volume ratio of the resulting mixture was 1:2.5 to ensure complete charge and discharge of Siol-NDI. Argon gas was bubbled through the mixture for 10 minutes. The derivatives Siol-NDI and FcNCl were used as the anolyte and catholyte of the battery, respectively, and are referred to as 0.1 M Siol-NDI / 0.1 FcNCl.

[0129] Step 3: Assemble a neutral aqueous organic redox flow battery and conduct performance tests;

[0130] (1) Place the fixture prepared in step one and the solution prepared in step two into the glove box. Use the prepared Siol-NDI solution as the anolyte and the MiAcNH-TEMPO solution as the catholyte. Connect the external power supply, peristaltic pump, and Xinwei tester, set the program, and the charge-discharge test can be performed.

[0131] Following the above steps, the basic test data for the prepared 0.1M siol-NDI / 0.1M MiAcNH-TEMPO system are as follows: two-electron storage, voltage range 0.1–1.8V, current density 40mA / cm². 2 After 3020 cycles, the capacity retention rate was 95.48%, the single-cycle capacity decay rate was 0.0015%, the total cycle time was 399.5 hours, the daily decay rate was 0.011% / hour, the theoretical capacity was 32.16 mAh, the actual capacity was 25.29 mAh, and the capacity utilization rate was 78.65%.

[0132] (2) Place the fixture prepared in step one and the solution prepared in step two into the glove box. Use the prepared Siol-NDI solution as the anolyte and the FcNCl solution as the catholyte. Connect the external power supply, peristaltic pump, and Xinwei tester, set the program, and the charge-discharge test can be performed.

[0133] Following the above steps, the basic test data for the prepared 0.1M Siol-NDI / 0.1M FcNCl system are as follows: two-electron storage, voltage range 0.1–1.5V, current density 40 mA / cm². 2 After 1400 cycles, the capacity retention rate was 86.31%, the single-cycle capacity decay rate was 0.00978%, the total cycle time was 178 hours, the daily decay rate was 0.077% / hour, the theoretical capacity was 32.16 mAh, the actual capacity was 24.68 mAh, and the capacity utilization rate was 76.74%.

[0134] Therefore, the above battery tests confirm that naphthalimide-based derivatives are excellent anolyte materials in neutral aqueous organic flow batteries. Compared to viologen molecules, naphthalimide molecules have stronger conjugation, greater rigidity, and larger molecular volume. Strong conjugation results in a narrower band gap for naphthalimide molecules, enabling rapid electron transfer and thus stable two-electron transfer. The large molecular volume prevents the anolyte from penetrating the ion exchange membrane during charge-discharge cycles. This invention increases the water solubility of the molecule through modification with quaternary ammonium salts and hydroxyl groups. Compared to previous studies, the number of water-soluble groups has increased from two to four, further increasing molecular water solubility, and the increase in water-soluble groups further increases the molecular size. In the electrochemical tests of two-electron transfer, neutral aqueous organic redox batteries based on 0.1M siol-NDI / 0.1M MiAcNH-TEMPO and 0.1M siol-NDI / 0.1M FcNCl both exhibited extremely strong stability. Furthermore, some other hydrophilic groups, such as:

[0135]

[0136] (where m takes values ​​from 1 to 10) can also be modified to further improve solubility and increase molecular volume, so as to obtain better anolyte materials.

[0137] The present invention conducted relevant tests on the Siol-NDI anode electrolyte material prepared in Example 1 above, and the test results are shown in [reference]. Figures 1-4 :

[0138] from Figure 1 As can be seen from the data, Example 1 has two redox peaks, located at -0.07V and -0.44V respectively.

[0139] from Figure 2 As can be seen from the data, when Example 1 is the anode electrolyte and FcNCl is the cathode electrolyte for two-electron transfer, the voltage window of the full cell is 1.05V; when Example 1 is the anode electrolyte and MiAcNH-TEMPO is the cathode electrolyte for two-electron transfer, the voltage window of the full cell can reach 1.29V.

[0140] Taking R=a as an example, denoted as siol-NDI, see [link / reference]. Figure 3 It can be seen that within the voltage test range of 0.1V-1.8V, when the current density is 40mA / cm² 2 At a concentration of 0.1 M, the neutral aqueous organic flow battery based on Siol-NDI / MiAcNH-TEMPO exhibited good cycle stability after 3020 cycles. After 3020 cycles, the capacity retention was 95.48%, and the capacity decay per cycle was 0.0015%.

[0141] Neutral aqueous organic flow batteries based on Siol-NDI / FcNCl also exhibited good stability. (See also...) Figure 4 ,from Figure 4 As can be seen, within the voltage test range of 0.1V-1.6V, after 1400 cycles of dual-electron cycling, the capacity retention rate is 86.31%, and the single-cycle capacity decay rate is 0.0098%.

[0142] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A hydrothermal synthesis method for a naphthimide derivative, characterized in that, The synthesis method is as follows: In a high-pressure reactor, precursor A and 3-chloro-1-propanol were reacted in water at 120°C for 24 h. After the reaction was completed, ethanol and acetone were added sequentially to the aqueous solution obtained from the reaction, and a pure product was precipitated. The product was filtered, washed three times with acetone, and dried under vacuum to obtain a grayish-white powder of the naphthalimide derivative Siol-NDI. The volume ratio of the aqueous solution obtained from the reaction to ethanol and acetone was 1:10:

2. The structural formula of precursor A is as follows: ； The structural formula of the obtained naphthalimide derivative siol-NDI is as follows: ； Precursor A is prepared by the following method: In a reaction vessel, compound B was dissolved in toluene, 3-dimethylaminopropylamine was added, and the mixture was heated to 120°C and reacted for 24 hours. After the reaction was completed, the mixture was filtered to obtain a golden yellow solid. The golden yellow solid was washed three times with ethanol and then dried under vacuum to obtain precursor A. The molar ratio of compound B to 3-dimethylaminopropylamine was 1:

5. The structural formula of compound B is as follows: 。

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