Naphtho[2,3-d]imidazolium-4,9-dione derivatives used as cathodes in organic lithium-ion batteries and their preparation methods

Abstract

This invention belongs to the field of lithium-ion battery material synthesis, specifically providing a naphtho[2,3-d]imidazolium-4,9-dione derivative for use as a cathode in organic lithium-ion batteries and its preparation method. First, 2,3-diamino-1,4-naphthoquinone is prepared using 2,3-dichloro-1,4-naphthoquinone and potassium phthalimide as raw materials. Then, 2,3-diamino-1,4-naphthoquinone is grafted onto glacial acetic acid, terephthalaldehyde, or 1,3,5-pyromellitic trimethylaldehyde to obtain naphtho[2,3-d]imidazolium-4,9-dione derivatives with different substitutions. Organic lithium-ion batteries using this derivative as a cathode can achieve high capacity and good cycle stability. The preparation method of this invention is simple and easy to implement, and the resulting electrode material exhibits good battery capacity and cycle life, showing broad application prospects in lithium-ion battery systems.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery material synthesis, and specifically provides a naphtho[2,3-d]imidazolium-4,9-dione derivative used as a cathode in organic lithium-ion batteries and its preparation method. Background Technology

[0002] The ever-increasing energy demand has spurred an urgent global need to develop cleaner and more environmentally friendly energy storage technologies. Lithium-ion batteries (LIBs) are widely used in various electric vehicles and power tools due to their advantages such as high energy density, long cycle life, and ease of large-scale production. Seeking electrode materials with superior electrochemical performance has always been a key focus in LIB development. Currently, the cathode materials for LIBs are mainly inorganic lithium salts, such as LiCoO2, LiMnO4, and LiFePO4. Although these inorganic lithium salts have been used in commercial LIBs, the toxicity, high cost, and poor recyclability of their transition metals have hindered their further widespread application in new energy vehicles.

[0003] Over the past decade, redox-active organic molecules have attracted considerable interest as electrode materials for lithium-ion batteries. Compared to transition metal-based inorganic electrode materials, organic electrode materials offer advantages such as low cost, environmental friendliness, structural diversity, ease of synthesis, and tunable electrochemical performance. To date, many organic molecules with different redox species have been studied as cathode materials for lithium-ion batteries. Among them, conjugated carbonyl compounds are considered the most promising materials due to their high theoretical specific capacity, good electrochemical activity, and ease of synthesis. However, their solubility in organic electrolytes severely hinders their practical application, resulting in poor cycle stability, low coulombic efficiency, and low specific capacity in conventional organic lithium-ion batteries.

[0004] Existing methods for addressing the low specific capacity of organic lithium-ion batteries mainly focus on increasing electrochemical active sites, such as grafting new active groups into organic electrode materials. However, existing electrode materials still suffer from low discharge capacity and low cycle life due to dissolution or decomposition. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance cathode material, a naphtho[2,3-d]imidazolium-4,9-dione derivative, for organic lithium-ion batteries. This material is synthesized from readily available raw materials, using a simple and easily scalable method with high yield. When applied to the cathode of lithium-ion batteries, this material exhibits advantages such as high electrochemical capacity and long cycle life, demonstrating broad application prospects.

[0006] The technical solution adopted in this invention is as follows: 2,3-diamino-1,4-naphthoquinone and potassium phthalimide are used as raw materials to prepare 2,3-diamino-1,4-naphthoquinone by reflux heating under nitrogen protection. The prepared 2,3-diamino-1,4-naphthoquinone was then reacted with glacial acetic acid, terephthalaldehyde, or 1,3,5-trimethylbenzaldehyde to obtain 2-methyl-1H-naphtho[2,3-d]imidazol-4,9-one (IMNQ-1), 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazol-4,9-dione (IMNQ-2), or 2,2',2”-(phenyl-1,3,5-triyl)tris(1H-naphtho[2,3-d]imidazol-4,9-dione (IMNQ-3). Finally, these three naphtho[2,3-d]imidazol-4,9-dione derivatives were used as cathode materials and assembled with lithium metal sheets to form organic lithium-ion batteries.

[0007] The organic lithium-ion battery provided by this invention, using a naphtho[2,3-d]imidazolium-4,9-dione derivative as the positive electrode material, operates as follows:

[0008] (1) Dissolve 2,3-dichloro-1,4-naphthoquinone and potassium phthalimide together in 200 mL of acetonitrile solution, reflux under nitrogen protection for 6-12 h, cool to room temperature, filter to obtain a yellow solid intermediate. Place this intermediate in a round-bottom flask, add 10 mL of hydrazine hydrate, and react at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone;

[0009] The mass ratio of 2,3-dichloro-1,4-naphthoquinone to potassium phthalimide is 1:1 to 1:3.

[0010] (2) 2,3-Diamino-1,4-naphthoquinone was added to glacial acetic acid and heated under reflux for 3-7 h under nitrogen protection. After cooling the product, it was washed with acetic acid, ethanol, ether and water respectively, and dried to obtain the gray product 2-methyl-1H-naphtho[2,3-d]imidazol-4,9-one (IMNQ-1);

[0011] The mass ratio of 2,3-diamino-1,4-naphthoquinone to glacial acetic acid is 1:168 to 1:300.

[0012] Alternatively, 2,3-diamino-1,4-naphthoquinone and terephthalaldehyde are added together to a flask, followed by 8 mL of DMSO. The mixture is stirred at 80–120 °C for 3–7 h. After cooling, the solvent is removed by filtration, followed by washing with ethanol and water in sequence. Finally, recrystallization in DMF yields the brownish-yellow product 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazol-4,9-dione (IMNQ-2).

[0013] The mass ratio of 2,3-diamino-1,4-naphthoquinone to terephthalaldehyde is 1:3 to 3:1.

[0014] Alternatively, 2,3-diamino-1,4-naphthoquinone and 1,3,5-trimethylbenzaldehyde are dissolved together in 15 mL of dimethyl sulfoxide solution and reacted in an oil bath at 80–120 °C for 6–24 h. After the reaction is complete, the mixture is cooled to room temperature and filtered to separate the brownish-yellow solid. This brownish-yellow solid is placed in a flask, and 200 mL of N,N-dimethylformamide (DMF) is added. The mixture is heated under reflux for 20 minutes, and the product is filtered, washed, and dried to remove residual DMF, yielding a bright yellow 2,2',2”-(benzyl-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazol-4,9-dione (IMNQ-3);

[0015] The mass ratio of 2,3-diamino-1,4-naphthoquinone to 1,3,5-trimethylbenzaldehyde is 1:4 to 4:1.

[0016] (3) Using the naphtho[2,3-d]imidazol-4,9-dione derivative prepared in step (2) as the positive electrode and lithium sheet as the negative electrode, an organic lithium-ion battery is assembled.

[0017] The separator used for assembling the battery is a porous polypropylene membrane (Celgard 2400) with a diameter of 19 mm. The electrolyte is 1,4-dioxane (DOL) and dimethyl ethylene glycol (DME) dissolved with 1 M LiTFSI and 1 wt.% LiNO3 (volume ratio 1:1).

[0018] The beneficial effects of this invention are as follows: This invention prepares three naphtho[2,3-d]imidazolium-4,9-dione derivatives, namely 2,3-diamino-1,4-naphthoquinone (IMNQ-1), 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazolium-4,9-dione (IMNQ-2), and 2,2',2”-(phenyl-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazolium-4,9-dione (IMNQ-3), which can be used as positive electrode materials for organic lithium-ion batteries to improve the electrochemical capacity and cycle life of organic lithium-ion batteries.

[0019] This invention not only provides an organic lithium-ion battery using a naphtho[2,3-d]imidazolium-4,9-dione derivative as the positive electrode material, but also solves the problems of low actual electrochemical capacity and short cycle life caused by dissolution in electrolyte that are common in existing organic lithium-ion batteries. Attached image description:

[0020] Figure 1 The BET specific surface area diagram of IMNQ-1 prepared in Example 1.

[0021] Figure 2 The 1H NMR spectrum of 2,3-diamino-1,4-naphthoquinone prepared in Example 1.

[0022] Figure 3 The organic lithium-ion battery IMNQ-1 / / Li assembled for Example 1 operates at a current density of 0.1 A g. -1 The following is a charge / discharge curve.

[0023] Figure 4 The organic lithium-ion battery IMNQ-1 / / Li assembled for Example 1 operates at a current density of 10 A g. -1 The cycle life diagram below.

[0024] Figure 5 The organic lithium-ion battery IMNQ-2 / / Li assembled for Example 2 operates at a current density of 0.1 A g. -1 The following is a charge / discharge curve.

[0025] Figure 6 The organic lithium-ion battery IMNQ-2 / / Li assembled in Example 2 operates at a current density of 10 A g. -1 The cycle life diagram below.

[0026] Figure 7 The 1H NMR spectrum of IMNQ-3 prepared in Example 3.

[0027] Figure 8 The organic lithium-ion battery IMNQ-3 / / Li assembled for Example 3 operates at a current density of 0.1 A g. -1 The following is a charge / discharge curve.

[0028] Figure 9 The organic lithium-ion battery IMNQ-3 / / Li assembled in Example 3 was tested at a current density of 10 A g. -1 The cycle lifetime and coulomb efficiency plots are shown below.

[0029] Figure 10 The charge-discharge curves of the organic lithium-ion battery e-PAQPy / / Li assembled in Comparative Example 1 are shown.

[0030] Figure 11 Cycle life diagram of the organic lithium-ion battery e-PAQPy / / Li assembled in Comparative Example 1. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] (1) 10 g of 2,3-dichloro-1,4-naphthoquinone and 16.5 g of potassium phthalimide were dissolved together in 200 mL of acetonitrile solution. The mixture was refluxed for 12 h under nitrogen protection, cooled to room temperature, and filtered to obtain a yellow solid intermediate. This intermediate was placed in a round-bottom flask, 10 mL of hydrazine hydrate was added, and the mixture was reacted at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone. The 1H NMR spectrum of the prepared 2,3-diamino-1,4-naphthoquinone is shown in the figure. Figure 2 The graph clearly shows the presence of three types of hydrogen peaks.

[0034] (2) 0.188 g of 2,3-diamino-1,4-naphthoquinone (1 mmol) was added to 30 mL of glacial acetic acid and refluxed for 7 h under nitrogen protection. After cooling, the product was washed with acetic acid, ethanol, diethyl ether, and water, respectively, and dried to obtain the gray product 2-methyl-1H-naphtho[2,3-d]imidazolium-4,9-one (IMNQ-1). The yield of IMNQ-1 was 92%, and the BET specific surface area was 48.9 m² / g. -1 ( Figure 1 The mass ratio of 2,3-diamino-1,4-naphthoquinone to glacial acetic acid is 1:168;

[0035] (3) An organic lithium-ion battery, IMNQ-1 / / Li, was assembled using the prepared 2-methyl-1H-naphtho[2,3-d]imidazolium-4,9-one (IMNQ-1) as the positive electrode and lithium sheet as the negative electrode. A porous polypropylene membrane (Celgard 2400) with a diameter of 19 mm was selected as the separator, and the electrolyte was 1,4-dioxane (DOL) and dimethyl ethylene glycol (DME) dissolved with 1 M LiTFSI and 1 wt.% LiNO3 (volume ratio 1:1).

[0036] Figure 3 The organic lithium-ion battery IMNQ-1 / / Li assembled for Example 1 operates at a current density of 0.1 A g. -1 The charge-discharge curves are shown below. The electrochemical capacity of this battery is 268 mAh g. -1 .

[0037] Figure 4 The organic lithium-ion battery IMNQ-1 / / Li assembled in Example 1 operates at a current density of 10 A g. -1 The following is a cycle life graph. After 3000 cycles, the capacity of the organic lithium-ion battery IMNQ-1 / / Li can still be maintained at 191 mAh g. -1 The capacity retention rate was 71.3%.

[0038] Example 2

[0039] (1) 10 g of 2,3-dichloro-1,4-naphthoquinone and 10 g of potassium phthalimide were dissolved together in 200 mL of acetonitrile solution and refluxed for 6 h under nitrogen protection. After cooling to room temperature, the mixture was filtered to obtain a yellow solid intermediate. This intermediate was placed in a round-bottom flask, 10 mL of hydrazine hydrate was added, and the mixture was reacted at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone.

[0040] (2) 0.402 g of 2,3-diamino-1,4-naphthoquinone and 0.134 g of terephthalaldehyde were added together to a flask, followed by 8 mL of DMSO. The mixture was stirred at 120 °C for 7 h. After cooling, the solvent was removed by filtration, and the product was washed with ethanol and water in sequence. Finally, it was recrystallized in DMF to obtain the brownish-yellow product 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazol-4,9-dione (IMNQ-2). The yield of IMNQ-2 was 94%. The mass ratio of 2,3-diamino-1,4-naphthoquinone to terephthalaldehyde was 3:1.

[0041] (3) Using the prepared 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazolium-4,9-dione (IMNQ-2) as the positive electrode and lithium sheet as the negative electrode, an organic lithium-ion battery IMNQ-2 / / Li was assembled. The battery assembly process was the same as in Example 1.

[0042] Figure 5 The organic lithium-ion battery IMNQ-2 / / Li assembled for Example 2 operates at a current density of 0.1 A g. -1 The charge-discharge curves are shown below. The electrochemical capacity of this battery is 398 mAh g. -1 .

[0043] Figure 6 The organic lithium-ion battery IMNQ-2 / / Li assembled in Example 2 operates at a current density of 10 A g. -1 Cycle life diagram below. At a current density of 10 A g -1 Under these conditions, the first-cycle discharge capacity of the organic lithium-ion battery IMNQ-1 / / Li is 292 mAh g. -1 After 1200 cycles, the battery capacity still remains at 218mAh g. -1 The capacity retention rate was 74.7%.

[0044] Example 3

[0045] (1) 10 g of 2,3-dichloro-1,4-naphthoquinone and 30 g of potassium phthalimide were dissolved together in 200 mL of acetonitrile solution and refluxed for 12 h under nitrogen protection. After cooling to room temperature, the mixture was filtered to obtain a yellow solid intermediate. This intermediate was placed in a round-bottom flask, 10 mL of hydrazine hydrate was added, and the mixture was reacted at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone.

[0046] (2) 0.648 g of 2,3-diamino-1,4-naphthoquinone and 0.162 g of 1,3,5-pyromellitic trimethylaldehyde were dissolved together in 15 mL of dimethyl sulfoxide solution and reacted in an oil bath at 120 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate a brownish-yellow solid. This brownish-yellow solid was placed in a flask, and 200 mL of N,N-dimethylformamide (DMF) was added. The mixture was heated under reflux for 20 minutes. The product was then filtered, washed, and dried to remove residual DMF, yielding a bright yellow 2,2',2”-(benzene-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazol-4,9-dione (IMNQ-3). The yield of IMNQ-3 was 97%. The mass ratio of 2,3-diamino-1,4-naphthoquinone to 1,3,5-pyromellitic trimethylaldehyde was 4:1.

[0047] (3) Using the prepared 2,2',2”-(phenyl-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazolium-4,9-dione (IMNQ-3) as the positive electrode and lithium sheet as the negative electrode, an organic lithium-ion battery IMNQ-3 / / Li was assembled. The battery assembly process was the same as in Example 1.

[0048] Figure 7 The image shows the prepared IMNQ-3 1H NMR spectrum. As can be seen from the figure, it is similar to... Figure 2 Compared to the 1H NMR spectrum of 2,3-diamino-1,4-naphthoquinone, the amino peak at 5.45 ppm disappeared, while the H peak... c and H b The peaks shifted to 8.00–7.99 ppm and 8.36–8.38 ppm, respectively. Simultaneously, a new peak appeared at 9.32 ppm, corresponding to the H on the benzene ring. a peak.

[0049] Figure 8 The organic lithium-ion battery IMNQ-3 / / Li assembled for Example 3 operates at a current density of 0.1 A g. -1 The charge-discharge curves are shown below. The electrochemical capacity of this battery is 648 mAh g. -1 .

[0050] Figure 9 The organic lithium-ion battery IMNQ-2 / / Li assembled in Example 3 operates at a current density of 10 A g.-1 The following is a cycle life graph. The capacity in the first cycle is 410 mAh g. -1 After 3000 cycles, the capacity of the organic lithium-ion battery IMNQ-1 / / Li is 308 mAh g. -1 The capacity retention rate was 75.1%.

[0051] Example 4

[0052] (1) 10 g of 2,3-dichloro-1,4-naphthoquinone and 16.5 g of potassium phthalimide were dissolved together in 200 mL of acetonitrile solution and refluxed for 12 h under nitrogen protection. After cooling to room temperature, the mixture was filtered to obtain a yellow solid intermediate. This intermediate was placed in a round-bottom flask, 10 mL of hydrazine hydrate was added, and the mixture was reacted at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone.

[0053] (2) 0.189 g of 2,3-diamino-1,4-naphthoquinone (1 mmol) was added to 54 mL of glacial acetic acid and heated under reflux for 7 h under nitrogen protection. After cooling, the product was washed with acetic acid, ethanol, ether, and water, respectively, and dried to obtain the gray product 2-methyl-1H-naphtho[2,3-d]imidazol-4,9-one (IMNQ-1). The yield of IMNQ-1 was 88%. The mass ratio of 2,3-diamino-1,4-naphthoquinone to glacial acetic acid was 1:300.

[0054] (3) An organic lithium-ion battery, IMNQ-1 / / Li, was assembled using the prepared 2-methyl-1H-naphtho[2,3-d]imidazolium-4,9-one (IMNQ-1) as the positive electrode and lithium sheet as the negative electrode. A porous polypropylene membrane (Celgard 2400) with a diameter of 19 mm was selected as the separator, and the electrolyte was 1,4-dioxane (DOL) and dimethyl ethylene glycol (DME) dissolved with 1 M LiTFSI and 1 wt.% LiNO3 (volume ratio 1:1).

[0055] The organic lithium-ion battery IMNQ-1 / / Li assembled using the organic materials prepared in Example 4 operates at a current density of 0.1 Ag. -1 The electrochemical capacity is 259 mAh g. -1 At a current density of 10 A g -1 The capacity retention rate after 3000 cycles was 66.7%.

[0056] Example 5

[0057] (1) 10 g of 2,3-dichloro-1,4-naphthoquinone and 10 g of potassium phthalimide were dissolved together in 200 mL of acetonitrile solution and refluxed for 6 h under nitrogen protection. After cooling to room temperature, the mixture was filtered to obtain a yellow solid intermediate. This intermediate was placed in a round-bottom flask, 10 mL of hydrazine hydrate was added, and the mixture was reacted at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone.

[0058] (2) 0.134 g of 2,3-diamino-1,4-naphthoquinone and 0.402 g of terephthalaldehyde were added together to a flask, followed by 8 mL of DMSO. The mixture was stirred at 120 °C for 7 h. After cooling, the solvent was removed by filtration, and the product was washed with ethanol and water in sequence. Finally, it was recrystallized in DMF to obtain the brownish-yellow product 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazol-4,9-dione (IMNQ-2). The yield of IMNQ-2 was 91%. The mass ratio of 2,3-diamino-1,4-naphthoquinone to terephthalaldehyde was 1:3.

[0059] (3) Using the prepared 2'2-(1,4-phenyl)p-(1H-naphtho[2,3-d]imidazolium-4,9-dione (IMNQ-2) as the positive electrode and lithium sheet as the negative electrode, an organic lithium-ion battery IMNQ-2 / / Li was assembled. The battery assembly process was the same as in Example 1.

[0060] The organic lithium-ion battery IMNQ-2 / / Li assembled using the organic electrode material prepared in Example 5 operates at a current density of 0.1 A g. -1 The electrochemical capacity is 486 mAh g. -1 At a current density of 10 A g -1 The capacity retention rate after 1200 cycles was 88.9%.

[0061] Example 6

[0062] (1) 10 g of 2,3-dichloro-1,4-naphthoquinone and 30 g of potassium phthalimide were dissolved together in 200 mL of acetonitrile solution and refluxed for 12 h under nitrogen protection. After cooling to room temperature, the mixture was filtered to obtain a yellow solid intermediate. This intermediate was placed in a round-bottom flask, 10 mL of hydrazine hydrate was added, and the mixture was reacted at 60 °C for 12 h to prepare a deep blue 2,3-diamino-1,4-naphthoquinone.

[0063] (2) 0.162 g of 2,3-diamino-1,4-naphthoquinone and 0.648 g of 1,3,5-pyromellitic trimethylaldehyde were dissolved together in 15 mL of dimethyl sulfoxide solution and reacted in an oil bath at 120 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate a brownish-yellow solid. This brownish-yellow solid was placed in a flask, and 200 mL of N,N-dimethylformamide (DMF) was added. The mixture was heated under reflux for 20 minutes. The product was then filtered, washed, and dried to remove residual DMF, yielding a bright yellow 2,2',2”-(benzene-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazol-4,9-dione (IMNQ-3). The yield of IMNQ-3 was 94%. The mass ratio of 2,3-diamino-1,4-naphthoquinone to 1,3,5-pyromellitic trimethylaldehyde was 1:4.

[0064] (3) Using the prepared 2,2',2”-(phenyl-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazolium-4,9-dione (IMNQ-3) as the positive electrode and lithium sheet as the negative electrode, an organic lithium-ion battery IMNQ-3 / / Li was assembled. The battery assembly process was the same as in Example 1.

[0065] Example 6: The assembled organic lithium-ion battery IMNQ-3 / / Li operates at a current density of 0.1 A g. -1 The charge / discharge capacity is 633mAh g. -1 The capacity retention rate after 3000 cycles was 78.8%.

[0066] Comparative Example 1: Synthesis of polypyrroloanthraquinone (e-PAQPy) and electrochemical performance of the assembled lithium-ion battery e-PAQPy / / Li.

[0067] In a 250 mL three-necked flask, 0.9 g (4.032 mmol) of 2-aminoanthraquinone, 1.05 mL (8.064 mmol) of 2,5-dimethoxytetrahydrofuran, 90 mL of N,N-dimethylformamide, 0.102 g (0.402 mmol) of iodine, and 3.6 mL of water were added. Under nitrogen protection, the mixture was heated to 120 °C in an oil bath and refluxed for 3 h. After the reactants cooled to room temperature, 300 mL of water was added, and the mixture was stirred to precipitate. After standing for 2 h, the precipitate was filtered. The resulting filter cake was a yellow solid. The product was washed 3-5 times with warm water and dried under vacuum at 60 °C for 12 h, with a yield of approximately 87%.

[0068] 100 mg of pyrroloanthraquinone monomer was dissolved in 30 mL of DMSO, and 4 mmol of LiClO4 was added. The mixture was placed in an electrolytic cell. Under nitrogen protection, electrolysis was performed at a constant potential of 1.7 V for 80 h, using a carbon felt electrode as the working and counter electrode and an Ag electrode as the quasi-reference electrode. After the reaction was completed, 300 mL of water was added, and a precipitate was formed. The precipitate was then filtered to obtain a dark brown primary product, which was washed 3-5 times with deionized water and dried under vacuum at 60 °C for 12 h to obtain polypyrroloanthraquinone (yield approximately 40%).

[0069] Figure 10 The charge-discharge diagram shows the e-PAQPy / / Li battery prepared in Comparative Example 1, using e-PAQPy as the positive electrode. The battery capacity is 197 mAh g. -1 .

[0070] Figure 11 This is a cycle life graph for the e-PAQPy / / Li battery. After 600 cycles, the battery retains 70% of its discharge capacity.

Claims

1. The application of a naphtho[2,3-d]imidazol-4,9-dione derivative, characterized in that, The derivative is used as a cathode material for organic lithium-ion batteries; The naphtho[2,3-d]imidazol-4,9-dione derivative is 2,2',2''-(phenyl-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazol-4,9-dione IMNQ-3, with the following molecular structure: ， IMNQ-3; An organic lithium-ion battery was assembled using a naphtho[2,3-d]imidazolium-4,9-dione derivative as the positive electrode and a lithium sheet as the negative electrode. The separator was a porous polypropylene membrane, and the electrolyte was 1,4-dioxane and ethylene glycol dimethyl ether containing 1 M LiTFSI and 1 wt.% LiNO3.

2. The application of the naphtho[2,3-d]imidazol-4,9-dione derivative as described in claim 1, characterized in that, The preparation steps of the derivative are as follows: (1) Dissolve 2,3-dichloro-1,4-naphthoquinone and potassium phthalimide in acetic acid solution, reflux under nitrogen protection for 6-12 h, cool to room temperature, filter to obtain a yellow solid intermediate product; place this yellow intermediate product in a round bottom flask, add hydrazine hydrate, react at 60 °C for 12 h to obtain deep blue 2,3-diamino-1,4-naphthoquinone; (2) Dissolve 2,3-diamino-1,4-naphthoquinone and 1,3,5-trimethylbenzenealdehyde together in DMSO solution and react in an oil bath. After the reaction is completed, cool to room temperature and filter to separate the brownish-yellow solid. Place the brownish-yellow solid in a flask, add N,N-dimethylformamide, heat under reflux for 20 minutes, filter, wash and dry the product to remove residual DMF and obtain bright yellow 2,2',2''-(benzene-1,3,5-triyl)tris(1H-naphthyl[2,3-d]imidazol-4,9-dione (IMNQ-3).

3. The application of the naphtho[2,3-d]imidazol-4,9-dione derivative as described in claim 2, characterized in that, The mass ratio of 2,3-dichloro-1,4-naphthoquinone and potassium phthalimide in step (1) is 1:1 to 1:

3.

4. The application of the naphtho[2,3-d]imidazol-4,9-dione derivative as described in claim 2, characterized in that, In step (2), the mass ratio of 2,3-diamino-1,4-naphthoquinone and 1,3,5-trimethylbenzaldehyde is 1:4 to 4:1, and the reaction conditions are 6 to 24 h in an oil bath at 80 to 120 °C.

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