Modified positive electrode polymer material, method for preparing same, and use thereof

Abstract

This invention discloses a modified cathode polymer material, its preparation method, and its application. The preparation method of the modified cathode polymer material includes the following steps: using 5,11-dihydroindolo[3,2-b]carbazole, Pd2(dba)3, Xphos, and sodium tert-butoxide as raw materials, mixing the raw materials and a first solvent until homogeneous to obtain a first system; mixing the first system and a dispersion containing carbon nanotubes at 120-125°C until homogeneous to obtain a second system; mixing the second system and a third system until homogeneous, stirring and reacting at 120-125°C under a nitrogen or inert gas atmosphere for 24-48 h, cooling to room temperature, post-treatment, and drying to obtain the modified cathode polymer material. The third system includes 1,4-dibromobenzene and a third solvent. This invention uses an in-situ composite method to firmly combine the indolo[3,2-b]carbazole-based polymer and carbon nanotubes, reducing the molecular plane angle between the carbazole molecule and the coupled benzene ring, improving the output voltage, and resulting in superior battery performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a modified cathode polymer material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, with their outstanding advantages such as long cycle life, high operating voltage, high energy density, high power density, and wide operating temperature range, have been widely used in portable electronic devices such as smartphones and laptops, as well as in new energy vehicles. They also show great potential in large-scale renewable energy storage. However, the development of traditional lithium-ion batteries faces many bottlenecks. For example, the theoretical specific capacity of their cathode materials (such as LiCoO2 and LiFePO4) is strictly limited by the stability of their crystal structure, making it difficult to achieve breakthrough improvements in energy density. Furthermore, the limited reserves and high prices of transition metals such as cobalt on Earth not only increase battery costs but also limit their application in large-scale energy storage scenarios. At the same time, the preparation of traditional inorganic electrode materials often requires a large amount of energy and easily releases harmful substances, posing a potential threat to the ecological environment. Therefore, these technological and industrial challenges urgently need to be overcome to promote the application of lithium-ion batteries in large-scale energy storage.

[0003] Organic electrode materials, as an important supplement to traditional inorganic electrode materials, have been extensively and deeply studied in the field of energy storage in recent years. Compared with inorganic electrode materials containing transition metals such as cobalt, organic electrode materials exhibit several significant advantages. First, the elemental composition of organic electrode materials is mainly composed of light elements such as carbon, hydrogen, oxygen, nitrogen, and sulfur. These elements are abundant and widely available in nature, not only being inexpensive but also possessing good environmental friendliness and sustainability, effectively avoiding the dependence of traditional inorganic materials on scarce metals. Second, the molecular structure of organic electrode materials has high designability and tunability, and is easy to chemically modify. Through reasonable molecular design and structural control, their electrochemical performance can be precisely optimized, thereby obtaining organic electrode materials with both high specific capacity and excellent cycle stability, providing new possibilities for breaking through the performance bottlenecks of traditional batteries. Therefore, with its multiple advantages such as resource friendliness, tunable performance, and green preparation, organic electrode materials are expected to become the core choice for next-generation high-efficiency and green energy storage materials, providing important support for solving the challenges currently facing energy storage technologies. However, organic electrode materials are typically dissolved in organic electrolytes, severely impacting battery capacity retention and cycle life. Furthermore, organic electrode materials generally exhibit poor conductivity and low electrochemical reaction potentials, which affect the battery's rate performance and limit its energy density.

[0004] Against this backdrop, synthesizing organic polymers from organic molecular units through polymerization can often effectively solve the problem of organic electrode dissolution. However, linear polymers, due to intermolecular interactions, often lead to polymer chain aggregation, resulting in insufficient utilization of electrochemical active sites and affecting the electrode's charge storage capacity. Improving the utilization rate of electrochemical active sites and preparing organic electrode materials with good cycle stability and low cost are urgent problems to be solved. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing modified cathode polymer materials.

[0006] Another object of the present invention is to provide a modified cathode polymer material obtained by the above preparation method.

[0007] Another object of the present invention is to provide a lithium organic battery.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A method for preparing a modified positive electrode polymer material includes the following steps:

[0010] Step 1: Using 5,11-dihydroindodo[3,2-b]carbazole (ICZ), tris(dibenzylacetone)dipalladium (Pd2(dba)3), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (Xphos), and sodium tert-butoxide (t-BuONa) as raw materials, the raw materials and the first solvent are mixed until homogeneous under a nitrogen or inert gas atmosphere to obtain the first system. The first system and the dispersion containing carbon nanotubes are mixed at 120~125°C until homogeneous to obtain the second system.

[0011] In step 1, the diameter (outer diameter) of the carbon nanotubes is 10~12 nm.

[0012] In step 1, the ratio of the molar amount of 5,11-dihydroindolo[3,2-b]carbazole in the raw material to the volume fraction of the first solvent is (1.9~2):(18~22), where the molar amount is in mmol and the volume fraction is in mL.

[0013] In step 1, the raw materials and the first solvent are mixed at room temperature and stirred until homogeneous to obtain the first system. The first system is heated to 120~125°C, and the first system and the dispersion containing carbon nanotubes are mixed at 120~125°C and stirred until homogeneous at 120~125°C to obtain the second system.

[0014] In step 1, the method for preparing the dispersion containing carbon nanotubes includes: mixing carbon nanotubes and a second solvent at room temperature, and sonicating for 20-30 min to obtain the dispersion containing carbon nanotubes, wherein the ratio of the mass fraction of carbon nanotubes to the volume fraction of the second solvent is (100.45-100.55):(18-22), where the mass fraction is in mg and the volume fraction is in mL.

[0015] Step 2: Mix all the second and third systems from Step 1 until homogeneous, stir and react at 120~125°C under nitrogen or inert gas atmosphere for 24~48 h, cool to room temperature, post-process, and dry to obtain modified positive electrode polymer material, wherein the third system includes: 1,4-dibromobenzene and a third solvent.

[0016] The molar ratios of 5,11-dihydroindodo[3,2-b]carbazole, tris(dibenzylacetone)dipalladium (Pd2(dba)3), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (Xphos), sodium tert-butoxide (t-BuONa), and 1,4-dibromobenzene are (1.9~2):(0.34~0.44):(0.73~0.83):(7.75~7.85):(1.9~2). The mass of carbon nanotubes in the dispersion containing carbon nanotubes is 5~10 wt% of the sum of the masses of 5,11-dihydroindodo[3,2-b]carbazole and 1,4-dibromobenzene.

[0017] In step 2, the post-processing includes: immersing the product obtained by cooling to room temperature in methanol, stirring to remove soluble impurities, filtering to obtain powder, and washing the filtered powder sequentially with water, toluene, N,N-dimethylformamide, dichloromethane, and anhydrous ethanol.

[0018] In step 2, the method for obtaining the third system includes: mixing 1,4-dibromobenzene and a third solvent until homogeneous to obtain the third system, wherein the molar fraction of 1,4-dibromobenzene and the volume fraction of the third solvent are (1.9~2):(28~32), the molar fraction is in mmol and the volume fraction is in mL.

[0019] In the above technical solution, the first solvent, the second solvent, and the third solvent are all toluene.

[0020] The modified cathode polymer material obtained by the above preparation method.

[0021] A lithium organic battery, comprising: the modified cathode polymer material.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. In this invention, the coupled benzene ring plays a dual synergistic role: introducing a benzene ring (i.e., the coupled benzene ring) onto the ICZ framework increases the conjugated plane of the ICZ, extends the π-conjugated framework to enhance electron delocalization and promote charge transport, and forms a robust PBICZ; the coupled benzene ring produces an electron-withdrawing effect, finely regulating the electron cloud density of the ICZ core (nitrogen atoms have a high electron cloud density, and the coupled benzene ring can extend π-electron delocalization, reducing the electron cloud density around nitrogen atoms). This electronic modulation lowers the energy level of the lowest unoccupied molecular orbital (the LUMO value of ICZ is -2.128 eV, and the LUMO value of PBICZ is -2.405 eV), thereby making the molecular energy level band gap of PBICZ smaller than that of ICZ, thus improving the redox potential of PBICZ, and consequently improving the cycle performance and rate performance of lithium organic batteries.

[0024] 2. This invention obtains PBICZ@CNT through Buchwald-Hartwig coupling, and uses an in-situ composite method to firmly bind the indole-carbazole polymer PBICZ and carbon nanotubes (CNTs), improving conductivity. PBICZ extends on the CNT surface, reducing the molecular plane angle between the carbazole molecule and the coupled benzene ring, further enhancing electron delocalization, promoting charge transport, reducing the molecular band gap, increasing output voltage, and resulting in superior battery performance.

[0025] 3. This invention employs a simple one-step coupling reaction to prepare modified cathode polymer materials (PBICZ@CNT). These modified cathode polymer materials exhibit good stability and excellent electrochemical performance in practical applications. The preparation method of this invention is simple, has a short cycle time, and uses environmentally friendly consumables. The raw materials used in this invention are widely available and inexpensive. Attached Figure Description

[0026] Figure 1 This is a microscopic molecular model diagram of PBICZ@CNT prepared in Example 1;

[0027] Figure 2 Scanning electron microscope images of the modified positive electrode polymer material prepared in Example 1;

[0028] Figure 3 Transmission electron microscope images of the modified positive electrode polymer material prepared in Example 1;

[0029] Figure 4 A scanning electron microscope image of the unmodified positive electrode polymer material prepared in Comparative Example 1;

[0030] Figure 5 Here is a scanning electron microscope image of the cathode material prepared in Comparative Example 2;

[0031] Figure 6 For the half-cell in test example 1 at 0.3mV s -1 CV curves at different scanning speeds;

[0032] Figure 7 For the half-cell in test example 1 at 0.5 A g -1 Charge-discharge curves at current density;

[0033] Figure 8 The rate performance graph of the half-cell in Test Example 1;

[0034] Figure 9 For the half-cell in test example 1 at 0.5 A g -1 Cyclic performance diagram at current density;

[0035] Figure 10 For the half-cell in test example 2 at 0.5 A g -1 Cyclic performance diagram at current density;

[0036] Figure 11 For the full cell in test example 3 at 0.3mV s -1 CV curves at different scanning speeds;

[0037] Figure 12 For the full cell in test example 3 at 0.5 A g -1 Charge-discharge curves at current density;

[0038] Figure 13 For the full cell in test example 3 at 0.5 A g -1 Cyclic performance diagram at current density;

[0039] Figure 14 To test the half-cell in Example 1 at 2 A g -1 Cyclic performance diagram at current density;

[0040] Figure 15 The angle between the molecular plane of the carbazole molecule and the coupled benzene ring corresponding to PBICZ@CNT, and the angle between the molecular plane of the carbazole molecule and the coupled benzene ring corresponding to PBICZ.

[0041] Figure 16 The PBICZ prepared for Comparative Example 1 13 C NMR spectrum. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0043] The raw materials and their manufacturers involved in the following examples and comparative examples are as follows:

[0044]

[0045] The instruments and their model information involved in the following embodiments and comparative examples are as follows:

[0046]

[0047] Battery performance testing was conducted using a battery testing system; the test voltage range was 2~4.5V.

[0048] 1C = 0.159 A g -1 .

[0049] In the test case, the aluminum mesh had an inner mesh diameter of 0.5*1.0mm and an opening ratio of 45~48%.

[0050] In Example 1 and Comparative Example 2 below, the method for preparing the dispersion containing carbon nanotubes includes: mixing carbon nanotubes and a second solvent (toluene) at room temperature, and sonicating at a frequency of 40 kHz for 20 min to disperse the carbon nanotubes uniformly, thereby obtaining the dispersion containing carbon nanotubes. The mass fraction of carbon nanotubes and the volume fraction of the second solvent are 100.5:20, the unit of mass fraction is mg, the unit of volume fraction is mL, and the tube diameter (outer diameter) of the carbon nanotubes is 10~12 nm (purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.).

[0051] Example 1

[0052] A method for preparing a modified positive electrode polymer material includes the following steps:

[0053] Step 1: A mixture of 5,11-dihydroindodo[3,2-b]carbazole (ICZ), tris(dibenzylacetone)dipalladium (Pd2(dba)3), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (Xphos), and sodium tert-butoxide (t-BuONa) was used as a raw material. The raw material was placed in a dry round-bottom flask, and under a nitrogen atmosphere, the raw material and the first solvent (toluene) were stirred at room temperature until homogeneous to obtain the first system. The first system was heated to 120°C, and the first system and the dispersion containing carbon nanotubes were mixed at 120°C and stirred at 120°C until homogeneous to obtain the second system. The molar ratio of 5,11-dihydroindodo[3,2-b]carbazole in the raw material to the volume ratio of the first solvent was 1.95:20. The molar ratio is in mmol, and the volume ratio is in mL.

[0054] Step 2: Mix all of the second and third systems from Step 1 (add the third system dropwise to the round-bottom flask from Step 1), stir and react at 120°C under a nitrogen atmosphere for 24 h, cool to room temperature to obtain the product, post-process the product, dry at 80°C for 12 h, and manually grind for 20 min to obtain the modified positive electrode polymer material (PBICZ@CNT, solid powder). The method for obtaining the third system includes: mixing 1,4-dibromobenzene (DBB) and the third solvent (toluene), stirring at room temperature until homogeneous to obtain the third system. The molar ratio of 1,4-dibromobenzene to the volume ratio of the third solvent is 1.95:30, where the molar ratio is in mmol and the volume ratio is in mL. The post-processing includes: immersing the product obtained after cooling to room temperature in methanol, stirring for 5 h to remove soluble impurities, filtering to obtain the powder, and washing the filtered powder sequentially with deionized water, toluene, N,N-dimethylformamide, dichloromethane, and anhydrous ethanol.

[0055] The molar ratios of 5,11-dihydroindodo[3,2-b]carbazole, tris(dibenzylacetone)dipalladium (Pd2(dba)3), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (Xphos), sodium tert-butoxide (t-BuONa), and 1,4-dibromobenzene are 1.95:0.39:0.78:7.8:1.95; the mass of carbon nanotubes in the dispersion is 5 wt% of the sum of the masses of 5,11-dihydroindodo[3,2-b]carbazole and 1,4-dibromobenzene.

[0056] In Example 1, the stirring speed was 500 r / min.

[0057] Comparative Example 1

[0058] A method for preparing an unmodified positive electrode polymer material includes the following steps:

[0059] Step 1: A mixture of 5,11-dihydroindodo[3,2-b]carbazole (ICZ), tris(dibenzylacetone)dipalladium (Pd2(dba)3), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (Xphos), and sodium tert-butoxide (t-BuONa) was used as a raw material. The raw material was placed in a dry round-bottom flask, and the raw material and the first solvent (toluene) were stirred at room temperature until homogeneous under a nitrogen atmosphere to obtain the first system. The molar ratio of 5,11-dihydroindodo[3,2-b]carbazole in the raw material to the volume ratio of the first solvent was 1.95:20. The molar ratio is expressed in mmol, and the volume ratio is expressed in mL.

[0060] Step 2: Heat the first system to 120°C, mix all of the first and third systems from Step 1 at 120°C, stir and react at 120°C under a nitrogen atmosphere for 24 h, cool to room temperature to obtain the product, post-process the product, dry at 80°C for 12 h, manually grind for 20 min to obtain unmodified positive electrode polymer material (PBICZ (molecular weight 8000 g / mol, degree of polymerization n=24), solid powder). The method for obtaining the third system includes: mixing 1,4-dibromobenzene (DBB) and a third solvent (toluene), stirring at room temperature until homogeneous, obtaining the third system. The molar ratio of 1,4-dibromobenzene to the volume ratio of the third solvent is 1.95:30, with molar fractions in mmol and volume fractions in mL. Post-processing includes: immersing the product obtained after cooling to room temperature in methanol, stirring for 5 minutes... h removes soluble impurities, and after filtration, the powder is obtained. The filtered powder is then washed sequentially with deionized water, toluene, N,N-dimethylformamide, dichloromethane, and anhydrous ethanol.

[0061] The molar ratios of 5,11-dihydroindolo[3,2-b]carbazole, tris(dibenzylacetone)dipalladium (Pd2(dba)3), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (Xphos), sodium tert-butoxide (t-BuONa), and 1,4-dibromobenzene are 1.95:0.39:0.78:7.8:1.95.

[0062] Comparative Example 2

[0063] The preparation of a cathode material includes: drying a dispersion containing carbon nanotubes (at a temperature of 80°C for 6 hours), manually grinding it for 20 minutes, and obtaining pure carbon nanotube (CNT) powder as the cathode material.

[0064] like Figure 1 As shown, ICZ reacts with DBB (1,4-dibromobenzene) to generate PBICZ (indolocarbazolyl polymer), and PBICZ attaches to CNTs to form PBICZ@CNT.

[0065] Scanning electron microscope image of the modified positive electrode polymer material prepared in Example 1 is shown below. Figure 2 As shown, by Figure 2 As can be seen, the modified cathode polymer material exhibits a distinct linear morphology. The scanning electron microscope image of the cathode material prepared in Comparative Example 2 is shown below. Figure 5 As shown, the cathode material prepared in Comparative Example 2 exhibits a distinct linear morphology and retains the open structure of carbon nanotubes. Figure 2 and Figure 5 The magnification is the same, but Figure 2 The width of the single linear structure in the middle is significantly greater than Figure 5 This indicates that PBICZ is attached to CNTs, and the modified cathode polymer material retains the open structure of carbon nanotubes, which is beneficial for the transport of ions and electrons.

[0066] Transmission electron microscope image of the modified positive electrode polymer material prepared in Example 1 is shown below. Figure 3 As shown, by Figure 3 It can be observed that the diameter of the carbon nanotubes is about 10 nm, and PBICZ with a thickness of about 3 nm are deposited on the outer surface of the carbon nanotubes, with a relatively uniform stacking state.

[0067] Scanning electron microscope image of the unmodified positive electrode polymer material prepared in Comparative Example 1 is shown below. Figure 4 As shown, the unmodified cathode polymer material exhibits a distinct granular morphology, is relatively pure overall, and no impurities were observed.

[0068] like Figure 15 As shown, the molecular plane angle between the carbazole molecule and the coupled benzene ring in the unmodified cathode polymer material prepared in Comparative Example 1 is 62.35°, while the molecular plane angle between the carbazole molecule and the coupled benzene ring in the modified cathode polymer material prepared in Example 1 is 41.91°. This indicates that PBICZ extends on the CNT surface, reducing the molecular plane angle between the carbazole molecule and the coupled benzene ring, further enhancing electron delocalization and promoting charge transport.

[0069] The unmodified positive electrode polymer material prepared in Comparative Example 1 13 C NMR characterization as follows Figure 16 As shown, the results indicate that the chemical shift of each carbon atom in the unmodified cathode polymer material prepared in Comparative Example 1 matches the theoretical chemical shift value well.

[0070] Test Example 1

[0071] A half-cell (lithium organic battery, CR2032 coin cell) includes: a negative electrode, a positive electrode, and a separator. The negative electrode is a lithium metal sheet (12 mm in diameter). The separator is a polypropylene separator wetted by an electrolyte. The electrolyte is a mixture of electrolyte and solvent. The concentration of the electrolyte in the electrolyte is 1 M. The electrolyte is LiPF6. The solvent is a mixture of ethylene carbonate (EC), dimethyl carbonate (DEC), and ethyl methyl carbonate (EMC). By mass, the ratio of EC, DEC, and EMC is 1:1:1. The half-cell is assembled in a glove box under an argon atmosphere, wherein the humidity and oxygen content in the glove box are both below 0.1 ppm. The outer casing of the half-cell is a CR2032 coin cell casing. The method for preparing the positive electrode sheet includes: mixing the positive electrode material, a polytetrafluoroethylene (PTFE) aqueous solution (the concentration of PTFE in the PTFE aqueous solution is 5 wt%), and acetylene black to obtain a slurry; using a glass tube, rolling the slurry onto a positive electrode current collector (aluminum mesh) to achieve a coating thickness of 300 μm; drying in a vacuum drying oven at 80°C for 12 h; and cutting into small circular pieces with a diameter of 12 mm using a slicing machine to obtain the positive electrode sheet. The ratio of PTFE to acetylene black in the positive electrode material, PTFE aqueous solution, and PTFE solution, by mass, is 6:3:1. The positive electrode material is one of the modified positive electrode polymer material prepared in Example 1 and the unmodified positive electrode polymer material prepared in Comparative Example 1.

[0072] Test Example 2

[0073] A half-cell (lithium organic battery, CR2032 coin cell) includes: a negative electrode, a positive electrode, and a separator. The negative electrode is a lithium metal sheet (12 mm in diameter). The separator is a polypropylene separator wetted by an electrolyte. The electrolyte is a mixture of electrolyte and solvent. The concentration of the electrolyte in the electrolyte is 1 M. The electrolyte is LiPF6. The solvent is a mixture of ethylene carbonate (EC), dimethyl carbonate (DEC), and ethyl methyl carbonate (EMC). By mass, the ratio of EC, DEC, and EMC is 1:1:1. The half-cell is assembled in a glove box under an argon atmosphere, wherein the humidity and oxygen content in the glove box are both below 0.1 ppm. The outer casing of the half-cell is a CR2032 coin cell casing. The method for preparing the positive electrode sheet includes: mixing the positive electrode material (the positive electrode material prepared in Comparative Example 2), polyvinylidene fluoride (PVDF), N-methylpyrrolidone, and acetylene black until uniform to obtain a slurry; coating the slurry onto the positive electrode current collector (aluminum foil) using a doctor blade to a thickness of 200 μm; drying in a vacuum drying oven at 80 °C for 12 h; and cutting the slurry into small circular pieces with a diameter of 12 mm using a slicer to obtain the positive electrode sheet. The ratio of the positive electrode material, PVDF, and acetylene black by mass is 8:1:1, and the ratio of the mass parts of PVDF to the volume parts of N-methylpyrrolidone is 1:20. The unit of mass parts is mg, and the unit of volume parts is mL.

[0074] Test Example 3

[0075] A full battery (lithium organic battery, CR2032 coin cell) includes: a negative electrode, a positive electrode, and a separator. The separator is a polypropylene separator wetted by an electrolyte. The electrolyte is a mixture of electrolyte and solvent. The concentration of the electrolyte in the electrolyte is 1M. The electrolyte is LiPF6. The solvent is a mixture of ethylene carbonate (EC), dimethyl carbonate (DEC), and ethyl methyl carbonate (EMC). By mass, the ratio of EC, DEC, and EMC is 1:1:1. The full battery is assembled in a glove box under an argon atmosphere. The humidity and oxygen content in the glove box are both below 0.1 ppm. The outer casing of the full battery is a CR2032 coin cell casing. The method for preparing the positive electrode sheet includes: mixing the positive electrode material (the modified positive electrode polymer material prepared in Example 1), a polytetrafluoroethylene (PTFE) aqueous solution (the concentration of PTFE in the polytetrafluoroethylene (PTFE) aqueous solution is 5wt%), and acetylene black to obtain a positive electrode slurry; using a glass tube, the positive electrode slurry is rolled onto a positive electrode current collector (aluminum mesh) to coat it with a thickness of 300μm; drying it in a vacuum drying oven at 80℃ for 12h; and cutting it into small circular pieces with a diameter of 12mm using a slicer to obtain the positive electrode sheet. The ratio of the positive electrode material, PTFE in the polytetrafluoroethylene (PTFE) aqueous solution, and acetylene black, by mass, is 6:3:1. The method for preparing the negative electrode sheet includes: mixing the negative electrode material (graphite, purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd., item number MA-EN-AN-0019), PVDF, N-methylpyrrolidone, and acetylene black until uniform to obtain a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector (copper foil with a thickness of 35 μm) using a scraper to achieve a coating thickness of 500 μm; drying in a vacuum drying oven at 80℃ for 12 h; and cutting into small circular pieces with a diameter of 12 mm using a slicer to obtain the negative electrode sheet. The ratio of negative electrode material, PVDF, and acetylene black by mass is 8:1:1, and the ratio of the mass parts of PVDF to the volume parts of N-methylpyrrolidone is 1:20. The unit of mass parts is mg, and the unit of volume parts is mL.

[0076] Cyclic voltammetry (CV) tests were performed on the half-cell prepared from the modified cathode polymer material of Example 1 and the half-cell prepared from the unmodified cathode polymer material of Comparative Example 1 using an electrochemical workstation. The scan rate was 0.3 mV / s. At the 20th cycle, the cycle capacity and coulombic efficiency of the half-cell were stable (close to 100%). The results of the 20th cycle were plotted on [the graph / image / data]. Figure 6 ,Depend on Figure 6 It can be seen that the half-cell prepared from the modified positive electrode polymer material of Example 1 ( Figure 6 The "PBICZ@CNT" has a larger integral area and current response strength.

[0077] At 0.5 A g-1 At a current density of [value missing], charge-discharge tests were performed on the half-cell prepared from the modified cathode polymer material of Example 1 and the half-cell prepared from the unmodified cathode polymer material of Comparative Example 1. The charge-discharge curves obtained are shown below. Figure 7 As shown, by Figure 7 It can be seen that the half-cell prepared from the modified positive electrode polymer material of Example 1 ( Figure 7 The "PBICZ@CNT" has a larger discharge specific capacity (129.2 mAh g). -1 It also provides a wider voltage plateau. The average discharge potential of the half-cell prepared from the modified cathode polymer material of Example 1 is as high as 3.7 V.

[0078] The half-cell prepared from the modified positive electrode polymer material of Example 1 and the half-cell prepared from the unmodified positive electrode polymer material of Comparative Example 1 were subjected to discharge tests at different current densities, and the results were as follows: Figure 8 The rate performance graph shown illustrates the results of 10 cycles at each current density, with one discharge specific capacity obtained per cycle, starting from 0.1 A g. -1 0.2 A g -1 0.5 A g -1 1 A g -1 Increased to 2 A g -1 Then it gradually decreased back to 1 A g -1 0.5 A g -1 0.2A g -1 0.1 A g -1 . Figure 8 This indicates that the half-cell prepared from the modified positive electrode polymer material of Example 1 ( Figure 8 The rate capability of "PBICZ@CNT" is even better.

[0079] At 0.5A g -1 At a current density, the half-cell prepared from the modified cathode polymer material of Example 1 and the half-cell prepared from the unmodified cathode polymer material of Comparative Example 1 were subjected to charge-discharge tests and cycled 1000 times. The cycle performance diagram is shown in the figure. Figure 9 As shown, by Figure 9 It can be seen that the half-cell prepared from the modified positive electrode polymer material of Example 1 ( Figure 9 The "PBICZ@CNT" series has an initial (first cycle) discharge specific capacity of 128.7 mAh g. -1 The discharge specific capacity in the 20th cycle was 128 mAh g. -1 After 1000 cycles, it can provide 103 mAh g. -1The discharge specific capacity. The half-cell prepared from the unmodified positive electrode polymer material of Comparative Example 1 ( Figure 9 The initial discharge specific capacity of "PBICZ" is 80 mAh g. -1 After 1000 cycles, it can provide 58 mAh g. -1 The specific discharge capacity.

[0080] At 0.5A g -1 At a current density of [value missing], the half-cell in Test Example 2 was subjected to charge-discharge tests and cyclic cycling for 100 cycles. The resulting cycle performance graph is shown in [figure missing]. Figure 10 As shown, by Figure 10 It can be seen that the discharge specific capacity of the half-cell prepared from the cathode material of Comparative Example 2 remained stable at 12 mAh g⁻¹ during 100 cycles. -1 The performance is far lower than that of the half-cell prepared from the modified positive electrode polymer material of Example 1.

[0081] Cyclic voltammetry (CV) tests were performed on the full cell in Test Example 3 using an electrochemical workstation (scan rate of 0.3 mV / s). The CV curves for the first 5 cycles were recorded, and the results are as follows: Figure 11 As shown, by Figure 11 It can be seen that the full cell prepared from the modified cathode polymer material of Example 1 has a large current response intensity and a high redox potential, with an oxidation potential of 3.9V and a reduction potential of 3.7V.

[0082] At 0.5 A g -1 At a current density of [value missing], the full cell in Test Example 3 was subjected to five consecutive constant current charge-discharge tests, and the obtained charge-discharge curves were plotted on [data missing]. Figure 12 ,Depend on Figure 12 It can be seen that the full cell prepared from the modified cathode polymer material of Example 1 has a large discharge specific capacity (average value of 122 mAh g). -1 It has a wide voltage plateau. The average discharge voltage is as high as 3.6V.

[0083] At 0.5 A g -1 At a current density of [value missing], the full cell in Test Example 3 was subjected to charge-discharge tests and 200 cycles. The resulting cycle performance graph is shown in the figure below. Figure 13 As shown, by Figure 13 It can be seen that the initial discharge specific capacity of the full cell prepared from the modified cathode polymer material of Example 1 is 121.7 mAh g. -1 After 200 cycles, the discharge specific capacity reaches as high as 100.9 mAh g. -1 .

[0084] In 2 Ag -1At a current density, the half-cell prepared from the modified cathode polymer material of Example 1 and the half-cell prepared from the unmodified cathode polymer material of Comparative Example 1 were subjected to charge-discharge tests and cycled 1000 times. The cycle performance diagram is shown in the figure. Figure 14 As shown, by Figure 14 It can be seen that the half-cell prepared from the modified positive electrode polymer material of Example 1 ( Figure 14 The discharge specific capacity of "PBICZ@CNT" in the 20th cycle was 98.5 mAh g. -1 After 1000 cycles, it can provide 79.8 mAh g. -1 The discharge specific capacity is significantly higher than that of the half-cell prepared from the unmodified cathode polymer material in Comparative Example 1. Figure 14 (in Chinese, "PBICZ").

[0085] In PBICZ, the coupled benzene ring synergistically interacts with ICZ, enhancing the redox kinetics and polymer stability of ICZ, reducing its molecular band gap, and increasing its conductivity. Furthermore, the redox potential of 5,11-dihydroindolo[3,2-b]carbazole (ICZ) is significantly higher than that of other p-type molecules, suggesting the potential for achieving higher operating voltages. The composite with carbon nanotubes further improves the stability of PBICZ.

[0086] In summary, the half-cells / full cells prepared based on the modified cathode polymer materials of this invention exhibit excellent electrochemical performance: high specific capacity and excellent cycle stability.

[0087] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a modified positive electrode polymer material, characterized in that, Includes the following steps: Step 1: Using 5,11-dihydroindodo[3,2-b]carbazole, tris(dibenzylacetone)dipalladium, 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl and sodium tert-butoxide as raw materials, the raw materials and the first solvent are mixed until homogeneous under a nitrogen or inert gas atmosphere to obtain the first system. The first system and the dispersion containing carbon nanotubes are mixed until homogeneous at 120~125°C to obtain the second system. Step 2: Mix all the second and third systems from Step 1 until homogeneous, stir and react at 120~125°C under nitrogen or inert gas atmosphere for 24~48 h, cool to room temperature, post-process, and dry to obtain modified positive electrode polymer material, wherein the third system includes: 1,4-dibromobenzene and a third solvent. The molar ratios of 5,11-dihydroindodo[3,2-b]carbazole, tris(dibenzylacetone)dipalladium, 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, sodium tert-butoxide, and 1,4-dibromobenzene are (1.9~2):(0.34~0.44):(0.73~0.83):(7.75~7.85):(1.9~2). The mass of carbon nanotubes in the dispersion containing carbon nanotubes is 5~10 wt% of the sum of the masses of 5,11-dihydroindodo[3,2-b]carbazole and 1,4-dibromobenzene.

2. The preparation method according to claim 1, characterized in that, In step 1, the diameter of the carbon nanotubes is 10~12 nm.

3. The preparation method according to claim 1, characterized in that, In step 1, the ratio of the molar amount of 5,11-dihydroindolo[3,2-b]carbazole in the raw material to the volume fraction of the first solvent is (1.9~2):(18~22), where the molar amount is in mmol and the volume fraction is in mL.

4. The preparation method according to claim 1, characterized in that, In step 1, the raw materials and the first solvent are mixed at room temperature and stirred until homogeneous to obtain the first system. The first system is heated to 120~125°C, and the first system and the dispersion containing carbon nanotubes are mixed at 120~125°C and stirred until homogeneous at 120~125°C to obtain the second system.

5. The preparation method according to claim 1, characterized in that, In step 1, the method for preparing the dispersion containing carbon nanotubes includes: mixing carbon nanotubes and a second solvent at room temperature, and sonicating for 20-30 min to obtain the dispersion containing carbon nanotubes, wherein the ratio of the mass fraction of carbon nanotubes to the volume fraction of the second solvent is (100.45-100.55):(18-22), where the mass fraction is in mg and the volume fraction is in mL.

6. The preparation method according to claim 1, characterized in that, In step 2, the post-processing includes: immersing the product obtained by cooling to room temperature in methanol, stirring to remove soluble impurities, filtering to obtain powder, and washing the filtered powder sequentially with water, toluene, N,N-dimethylformamide, dichloromethane, and anhydrous ethanol.

7. The preparation method according to claim 1, characterized in that, In step 2, the method for obtaining the third system includes: mixing 1,4-dibromobenzene and a third solvent until homogeneous to obtain the third system, wherein the molar fraction of 1,4-dibromobenzene and the volume fraction of the third solvent are (1.9~2):(28~32), the molar fraction is in mmol and the volume fraction is in mL.

8. The preparation method according to claim 1, characterized in that, The first solvent, the second solvent, and the third solvent are all toluene.

9. The modified cathode polymer material obtained by the preparation method according to any one of claims 1 to 8.

10. A lithium organic battery, comprising: The modified cathode polymer material according to claim 9.

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