A class of cyclic imide derivatives and their hydrothermal synthesis method and application in flow batteries

Abstract

The present invention discloses a class of cyclic imide derivatives, a hydrothermal synthesis method thereof, and an application in liquid flow batteries. The water solubility of the molecules is increased by ionizing dimethylammonium and other water-soluble modifications, and the water-soluble groups are increased from two to multiple, thereby significantly enhancing the water solubility of the molecules. The increase in water-soluble groups also increases the molecular size, which reduces the interaction between molecules and thus improves the stability of the molecules, solving the technical problems of weak conjugation of existing anode electrolyte molecules and low di-electron storage stability. The hydrothermal synthesis method requires only two steps of reaction, has low cost, high yield, short reaction time, and is suitable for mass production. When used as the negative electrode electrolyte of a neutral aqueous organic liquid flow battery, it exhibits extremely strong di-electron stability and other characteristics, and is suitable for large-scale energy storage of low-cost, high-capacity, high-power, and long-life neutral aqueous organic liquid flow batteries, which is of great significance to the development of imide derivatives in neutral aqueous liquid flow batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid flow battery electrolyte materials, and particularly relates to a class of cyclic imide derivatives and a hydrothermal synthesis method thereof and application in liquid flow batteries. Background Art

[0002] Energy is a vital material foundation of the national economy, and its development and effective utilization are directly linked to production technology and living standards. With the rapid development of renewable energy, the effective storage and regulation of these volatile energy sources has become a critical issue. Therefore, the development of new, efficient, and large-scale energy storage technologies is urgently needed. Large-scale energy storage technologies must meet at least three criteria: high safety, affordability, and environmental friendliness. Traditional large-scale energy storage technologies fall into three main categories: physical energy storage, battery storage, and electrochemical storage. However, none of these technologies can simultaneously meet both power and capacity requirements. Flow batteries are high-performance batteries that utilize separate, circulating positive and negative electrolytes. They boast high capacity, a wide range of applications, and a long cycle life. Their operating principle is the reversible redox reaction between the active substances in the positive and negative electrolyte solutions, converting electrical energy into chemical energy. This unique property makes flow batteries important in energy storage and regulation. Based on the active material, they can be categorized as inorganic or organic flow batteries. Inorganic flow batteries primarily include vanadium-based, zinc-based, and iron-based types. Organic flow batteries can be categorized as aqueous, non-aqueous, and hybrid organic flow batteries. Aqueous flow batteries can be classified by pH into acidic, alkaline, and neutral aqueous flow batteries. Transition metal flow batteries suffer from low energy density, high toxicity, specialized ion exchange membranes, high cost, and potential environmental issues. Aqueous RFBs, however, hold great potential in energy storage due to their flexibility, stability, scalability, adjustability, and safety.

[0003] Electrolyte materials, as a key component of flow batteries, play a crucial role in their capacity and stability. Developing low-cost, environmentally friendly, and highly stable positive and negative electrolytes is a challenge currently in need of resolution. While viologen and its derivatives are widely used in flow batteries, conventional viologen electrolyte materials have a low degree of conjugation. As the pyridine ring transitions from aromatic to antiaromatic properties during its transition from an oxidized to a highly reduced state, this significantly impacts di-electron stability. Therefore, viologen and its derivatives are generally used for single-electron storage.

[0004] Recently, imide substances have also begun to be used in liquid flow batteries. For example, after gaining electrons, the aromaticity of imide derivatives is enhanced, which is conducive to the stability of the two electrons. However, traditional synthesis methods are not only costly, but also waste time, manpower and other energy, which hinders their commercial development. Therefore, there is an urgent need to find new cost-effective synthesis methods to access imide molecules, which is of great significance for the development of commercial neutral aqueous liquid flow batteries using naphthylimide molecules. Summary of the Invention

[0005] In response to the technical problems that the existing anode electrolyte molecules have low conjugation and low two-electron storage stability, and the existing imide derivatives have long synthesis time and high cost, which limit their commercial development and application in neutral aqueous liquid flow batteries, the present invention aims to provide a class of imide derivatives and their hydrothermal synthesis method and application.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides an imide derivative, wherein the imide derivative is any one of the following structural formulas:

[0008]

[0009] Among them, R1 is Any one of the groups;

[0010] R2 is Any one of the groups;

[0011] n is 1 or 2.

[0012] A method for preparing the above-mentioned imide derivative comprises:

[0013] S1, preparation of precursor B;

[0014] S2, reacting the precursor B of step S1 with Cl-R2 to obtain a reaction solution, filtering the precipitate, and drying to obtain an imide derivative;

[0015] The preparation of the precursor B comprises: dissolving the precursor A, adding Reaction to obtain precursor B;

[0016] The precursor A is any one of the following structural formulas

[0017] described In the example, R1 is Any one of the groups;

[0018] n is 1 or 2.

[0019] The precursor A and The molar ratio is 1:3.

[0020] The solvent for dissolving the precursor A is any one of toluene, N,N-dimethylformamide, and tetrahydrofuran.

[0021] The molar ratio of the precursor B to Cl-R2 is 1:3;

[0022] In the Cl-R2, R2 is Any one of the groups.

[0023] The S2 reaction temperature is 110° C. to 130° C., and the reaction time is 22 h to 26 h.

[0024] The S2 precipitate was prepared by sequentially adding ethanol and acetone according to a volume ratio of 1:10:2 of reaction solution:ethanol:acetone.

[0025] The prepared precursor B is reacted at 110° C. to 130° C. for 20 h to 26 h.

[0026] The above-mentioned imide derivative is used in a liquid flow battery, wherein the liquid flow battery uses the imide derivative as the anode electrolyte and MiAcNH-TEMPO solution as the cathode electrolyte.

[0027] The volume ratio of the anolyte to the cathode electrolyte is 1:2.5-3.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention discloses a class of imide derivatives, which increase the water solubility of molecules by ionizing dimethylammonium and modifying other water solubilities. The number of water-soluble groups increases from two to four or more, which not only increases the water solubility of the molecules but also increases the molecular size. Compared with viologen molecules, the imide molecules of the present invention have stronger conjugation and aromaticity and larger molecular volume. The conjugation gradually increases from pyromellitic acid diimide to naphthalene diimide and then to perylene diimide. The strong conjugation narrows the band gap of the imide molecules, enabling rapid electron transfer and thus stable double electron transfer. The present invention solves the technical problems of weak conjugation and low double electron storage stability of existing anode electrolyte molecules (such as viologen).

[0030] The hydrothermal synthesis method of the imide derivative disclosed in the present invention can be achieved by only two steps of reaction, shortening the reaction time. By ionizing and modifying the terminal N atom, multiple hydrophilic groups are introduced, the molecular size is enlarged, and the water solubility of the molecule is improved. Compared with the imide molecules in the traditional synthesis method with quaternary ammonium salts, hydroxyl groups, phosphates or sulfonates as the side chains, the use of organic solvents such as N,N-dimethylformamide, tetrahydrofuran and acetonitrile can be effectively avoided. The solvent used in the reaction is low in price, the method is simple, the yield is high, and large-scale synthesis is possible.

[0031] The present invention provides an imide derivative for use as a negative electrode electrolyte in a flow battery. The negative electrode electrolyte is prepared using a class of imide derivatives of the present invention, ionized TEMPO is used as the positive electrode electrolyte, and a DSVN membrane is used as the anion exchange membrane to form a neutral aqueous organic flow battery with dual electron storage. The imide derivatives of the present invention have high solubility in water, a large output voltage within the range of water electrolysis, a relatively negative redox potential, a reversible redox peak, and exhibit extremely strong dual electron stability in electrochemical tests. Therefore, the imide derivatives can be used in low-cost, high-capacity, high-power, and long-life neutral aqueous organic flow batteries, which are suitable for commercial large-scale energy storage. This is of great significance to the development of imide derivatives in neutral aqueous flow batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a CV curve diagram of the imide derivative Pry-NDI of the present invention;

[0033] Figure 2 This is a full-cell CV curve diagram of a battery assembled with the imide derivative Pry-NDI of the present invention;

[0034] Figure 3 This is an electrochemical test diagram of a battery assembled with the imide derivative Pry-NDI of the present invention;

[0035] Figure 4 This is an electrochemical test diagram of a battery assembled with the imide derivative diol-PyrNDI of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0037] Example 1 Synthesis of imide derivative Pry-NDI

[0038] Take n = 2, R1 is R2 is

[0039] Precursor A is

[0040] (1) Preparation of precursor B:

[0041] The chemical reaction equation of precursor B is:

[0042]

[0043] In a reaction kettle, 15 g of precursor A was dissolved in 100 mL of toluene, 17.15 g of 1-(3-aminopropyl)pyrrole was added, and the mixture was heated to 120° C. for 24 h. After the reaction was completed, the mixture was filtered, and the golden solid was washed three times with ethanol and then vacuum dried to obtain precursor B. The structural formula of precursor B is as follows:

[0044] (2) Synthesis of imide derivative Pry-NDI

[0045] In a high-pressure reactor, 10 g of precursor B and 6.63 g of Cl-CH3 were weighed and placed in 59.8 mL of a 1 mol L -1 The reaction mixture was added to a tetrahydrofuran solution at 120°C for 24 hours to obtain a reaction solution; ethanol and acetone were added in sequence at a volume ratio of 1:10:2 reaction solution: ethanol: acetone. After the solid precipitated, it was filtered, washed with acetone three times, and dried in vacuo to obtain the imide derivative Pry-NDI as a light yellow powder with a yield of 90%.

[0046] The structural formula of the obtained imide derivative Pry-NDI is shown below:

[0047]

[0048] The specific hydrogen spectrum data of the obtained imide derivative Pry-NDI are as follows:

[0049] 1 H NMR (400MHz, Deuterium Oxide) δ8.62 (s, 4H), 4.23 (t, J = 7.0Hz, 4H), 3.60–3.47 (m, 12H), 3.04 (s, 6H), 2.31–2.16 (m, 12H).

[0050] It is proved that the above process synthesized the compound.

[0051] Example 2: Synthesis of imide derivative Pyrdiol-NDI

[0052] Take n = 2, R1 is R2 is

[0053] Precursor A is

[0054] (1) Preparation of precursor B:

[0055] The chemical reaction equation of precursor B is:

[0056]

[0057] In a reaction kettle, 15 g of precursor A was dissolved in 100 mL of N,N-dimethylformamide, and 17.15 g of N-(3-aminopropyl)pyrrole was added. The mixture was heated to 120°C and reacted for 24 h. After the reaction, the mixture was filtered, and the golden yellow powder was washed three times with ethanol and then vacuum dried to obtain precursor B. The structural formula of precursor B is as follows:

[0058]

[0059] (2) Synthesis of imide derivative Pry-NDI:

[0060] In a high-pressure reactor, 10 g of the precursor B obtained in (1) and 6.63 g of Cl-R were weighed and placed in 10 mL of water. The mixture was reacted at 120° C. for 24 h to obtain a reaction solution. Ethanol and acetone were added sequentially in a volume ratio of 1:10:2 reaction solution: ethanol: acetone. After the solid precipitated, it was filtered, washed with acetone three times, and vacuum dried to obtain a yellow powder of the imide derivative Pyr-diolNDI with a yield of 93%.

[0061] The structural formula of the obtained imide derivative Pyr-diolNDI is shown below:

[0062]

[0063] The specific hydrogen spectrum data of the obtained imide derivative Pry-diolNDI are as follows:

[0064] 1 H NMR (400MHz, Deuterium Oxide) δ8.61 (s, 4H), 4.28–4.11 (m, 6H), 3.69–3.36 (m, 20H), 2.19 (s, 12H).

[0065] Example 3: Synthesis of imide derivative dex-MoTPDI

[0066] Take n = 2, R1 is R2 is

[0067] Precursor A is

[0068] (1) Preparation of precursor B

[0069] The reaction formula of precursor B is as follows:

[0070]

[0071] In a reaction kettle, 10 g of compound A was dissolved in 100 mL of toluene, 11.03 g of 1-(3-aminopropyl)morpholine was added, and the mixture was heated to 120° C. for 24 h. After the reaction was completed, the mixture was filtered, and the brown solid was washed three times with ethanol and then vacuum dried to obtain precursor B. The structural formula of precursor B is as follows:

[0072]

[0073] (2) Synthesis of imide derivative dex-MoTPDI

[0074] In an autoclave, 10 g of precursor B and 8.78 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride were weighed and placed in 15 mL of water. The mixture was reacted at 120°C for 24 h to obtain a reaction solution. Ethanol and acetone were added sequentially in a volume ratio of 1:10:2 product:ethanol:acetone. After the solid precipitated, it was filtered, washed three times with acetone, and vacuum dried to obtain the imide derivative dex-TPDI as a red powder with a yield of 85%.

[0075] The structural formula of dex-MoTPDI is shown below:

[0076]

[0077] Example 4: Application of the imide derivatives of the present invention as anode electrolyte materials

[0078] The imide derivative Pyr-NDI prepared in Example 1 and Example 2 is used to prepare a neutral aqueous organic flow battery electrode material, which can be prepared by the following steps:

[0079] Step 1: Assemble the core fixture

[0080] The neutral aqueous organic redox flow battery used in the test is a single-cell structure. The positive terminal 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 terminal plate are bolted together in this order. External piping is connected and bolts are checked for looseness. If so, they can be tightened. Before testing, a leak and pressure test should be performed. Connect two liquid storage bottles and a peristaltic pump to the fixture. After 2 hours of circulation, if there is no leakage or change in liquid volume, the battery can be stored for future use. If any of these leaks occur, readjustment is required.

[0081] Step 2: Preparation of electrode materials

[0082] Prepare enough 2M NaCl solution in a volumetric flask, and use methylimidazole functionalized (2,2,6,6-tetramethylpiperidin-1-yl)oxy solution as the cathode electrolyte, with the chemical formula C 15 H 26 N4O2, referred to as MiAcNH-TEMPO.

[0083] (1) Preparation of 0.1M Pry-NDI / 0.1M MiAcNH-TEMPO neutral aqueous organic flow battery

[0084] Dissolve 362mg of Pry-NDI and 495mg of MiAcNH-TEMPO in 6mL and 15mL of 2M NaCl, respectively, with stirring or sonication to completely dissolve. The concentration of both in the NaCl solution is 0.1M. The resulting mixture has a volume ratio of 1:2.5 to ensure complete charge and discharge of Pry-NDI. Bubble argon for 10 minutes. The derivative Pry-NDI and MiAcNH-TEMPO serve as the anolyte and catholyte, respectively, in the battery, referred to as 0.1M Pry-NDI / 0.1MMiAcNH-TEMPO.

[0085] (2) Preparation of 0.1M diol-PryNDI / 0.1M MiAcNH-TEMPO neutral aqueous organic flow battery

[0086] Dissolve 426 mg of diol-PryNDI and 495 mg of MiAcNH-TEMPO in 6 mL and 15 mL of 2 M NaCl, respectively, with stirring or sonication to achieve complete dissolution. The concentration of both diol-PryNDI and MiAcNH-TEMPO in the NaCl solution was 0.1 M. The resulting mixture had a volume ratio of 1:2.5 to ensure complete charge and discharge of the diol-PryNDI. Bubble argon for 10 minutes. The diol-PryNDI derivative and MiAcNH-TEMPO served as the anolyte and catholyte, respectively, in the battery, referred to as 0.1 M diol-PryNDI / 0.1 M MiAcNH-TEMPO.

[0087] Step 3: Assemble the neutral aqueous organic redox flow battery and perform performance testing;

[0088] (1) Place the fixture prepared in step 1 and the solution from step 2 in a glove box. Use the prepared Pry-NDI / Prydiol-NDI solution as the negative electrolyte and the MiAcNH-TEMPO solution as the positive electrolyte. Connect an external power supply, peristaltic pump, and Newway tester, set the program, and perform the charge and discharge test.

[0089] (2) After the above steps, the basic test data of the prepared 0.1M Pry-NDI / 0.1M MiAcNH-TEMPO system are as follows: double electron storage, voltage range 0.1~1.8V, current density 40mA cm -2 After 1000 cycles, the capacity retention rate is 97.3% and the single-cycle capacity decay rate is 0.0027%.

[0090] (3) After the above steps, the basic test data of the prepared 0.1M diol-PryNDI / 0.1M MiAcNH-TEMPO system are as follows: double electron storage, voltage range 0.1~1.8V, current density 40mA cm -2 After 1050 cycles, the capacity retention rate was 92.3% and the single-cycle capacity decay rate was 0.007%.

[0091] Therefore, the above battery tests confirm that imide-based derivatives are excellent negative electrode electrolyte materials in neutral aqueous organic flow batteries. First, the imide molecules modified with hydrophilic groups have strong solubility in aqueous solutions, which ensures that such molecules can be used as electrolytes for neutral aqueous organic flow batteries. Second, the imide molecules have strong conjugation. During the process of double electron transfer, the molecular skeleton basically does not change, which is conducive to its double electron transfer. Strong conjugation makes the band gap of naphthalene imide molecules narrower, enabling rapid electron transfer and thus stable double electron transfer. The large molecular volume prevents the anode electrolyte from intercalating through the ion exchange membrane during the charge and discharge cycle. Compared with the more widely studied viologen molecules, the imide molecules are more conjugated and aromatic. During the process of double electron transfer, the aromaticity remains basically unchanged and the molecular volume is larger. The present invention increases the water solubility of the molecule by modifying it with quaternary ammonium salts and hydroxyl groups. Compared with previous studies, the number of water-soluble groups has increased from two to four, further increasing the water solubility of the molecule, and the increase in water-soluble groups has further increased the molecular size. In the electrochemical test of double electron transfer, the neutral aqueous organic redox batteries based on 0.1MPry-NDI / 0.1M MiAcNH-TEMPO and 0.1Mdiol-PryNDI / 0.1M MiAcNH-TEMPO both showed extremely strong stability. In addition, some other hydrophilic groups such as:

[0092]

[0093] (wherein the value of m is 1 to 10) can also be modified to further improve the solubility and expand the molecular volume to obtain a better negative electrode electrolyte material.

[0094] The present invention conducted relevant tests on the Pry-NDI and diol-PyrNDI anode electrolyte materials prepared in Example 1 and Example 2. The test results are shown in the attached Figure 1 ~Attachment Figure 4 .

[0095] By the attached Figure 1 The data show that the imide derivative Pry-NDI of Example 1 of the present invention has two redox peaks, located at -0.11V and -0.50V respectively.

[0096] By the attached Figure 2 The data show that the voltage window of the full cell can reach 1.35 V when double electron transfer is carried out using the imide derivative Pry-NDI of Example 1 of the present invention as the anode electrolyte and MiAcNH-TEMPO as the cathode electrolyte.

[0097] By the attached Figure 3The data show that in the electrochemical test of the neutral aqueous organic liquid flow battery obtained by using 0.1M Pry-NDI, an imide derivative of Example 1 of the present invention, as the anode electrolyte and 0.1M MiAcNH-TEMPO as the cathode electrolyte, the voltage test range is 0.1V-1.8V. When the current density is 40mA / cm 2 When the concentration is 0.1 M, the neutral aqueous organic flow battery based on Pry-NDI / MiAcNH-TEMPO shows good cycling stability over 1000 cycles; after 1000 cycles, the capacity retention rate is 97.3% and the single-cycle capacity decay rate is 0.0027%.

[0098] By the attached Figure 4 The data show that in the electrochemical test of the neutral aqueous organic liquid flow battery obtained by using 0.1M diol-PryNDI, an imide derivative of Example 1 of the present invention, as the anode electrolyte and 0.1M MiAcNH-TEMPO as the cathode electrolyte, the voltage test range is 0.1V-1.8V. When the current density is 40mA / cm 2 The neutral aqueous organic flow battery based on diol-PryNDI / MiAcNH-TEMPO showed good cycling stability over 1050 cycles; after 1050 cycles, the capacity retention rate was 92.3% and the single-cycle capacity decay rate was 0.007%.

[0099] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An imide derivative, characterized in that: The imide derivative has the following structure:

2. A method for preparing an imide derivative according to claim 1, characterized in that: include: S1, dissolve the precursor A and add Reaction to obtain precursor B; S2, the precursor B of step S1 reacts with Cl-R2 to obtain a reaction solution, precipitates, filters, and dries to obtain the imide derivative according to claim 1; wherein R2 is The structural formula of the precursor A is: The structural formula of the precursor B is:

3. The method for preparing an imide derivative according to claim 2, characterized in that: The precursor A and The molar ratio is 1:

3.

4. The method for preparing an imide derivative according to claim 2, characterized in that: The solvent used to dissolve the precursor A is any one of toluene, N,N-dimethylformamide, and tetrahydrofuran.

5. The method for preparing an imide derivative according to claim 2, wherein: The molar ratio of the precursor B to Cl-R2 is 1:

3.

6. The method for preparing an imide derivative according to claim 2, characterized in that: The S2 reaction temperature is 110° C. to 130° C., and the reaction time is 22 h to 26 h.

7. The method for preparing an imide derivative according to claim 2, characterized in that: For the S2 precipitation, ethanol and acetone were added in sequence according to the volume ratio of reaction solution: ethanol: acetone of 1:10:

2.

8. The method for preparing an imide derivative according to claim 2, characterized in that: The prepared precursor B is reacted at 110° C. to 130° C. for 20 h to 26 h.

9. The use of an imide derivative in a liquid flow battery according to claim 1, characterized in that: The liquid flow battery uses an imide derivative as an anode electrolyte and a MiAcNH-TEMPO solution as a cathode electrolyte.

10. Use of an imide derivative according to claim 9 in a neutral aqueous flow battery, characterized in that: The volume ratio of the anolyte to the cathode electrolyte is 1:2.5-3.

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