A conjugated microporous polymer and its preparation method and application

Abstract

The present invention discloses a novel conjugated microporous polymer, its preparation method, and application. The present invention uses benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide as raw materials and adopts a reversible Schiff base condensation reaction to synthesize a novel conjugated microporous polymer. The present invention also provides the application of the novel conjugated microporous polymer in anode materials for lithium-ion batteries. The novel conjugated microporous polymer prepared by the present invention has a high specific surface area and a porous structure. As anode materials for lithium-ion batteries, it facilitates electron transfer and ion transport, exhibits excellent electrochemical properties, and has good application prospects in the field of lithium-ion battery anode materials.

Description

Technical Field

[0001] The present invention relates to the field of lithium ion battery negative electrode materials, and in particular to a novel conjugated microporous polymer and a preparation method and application thereof. Background Art

[0002] With the rapid development of portable electronic devices and electric vehicles, electrochemical energy storage devices have become one of the hottest research areas. Among them, lithium-ion batteries (LIBs) have attracted much attention due to their significant advantages such as high energy density, high power density, long cycle life and low self-discharge rate. However, with the continuous growth of market demand and continuous technological advancement, the requirements for the performance of lithium-ion batteries are also constantly increasing. Although traditional lithium-ion battery anode materials such as graphite have stable performance and relatively low cost, they have great limitations in energy density and charge and discharge speed. Therefore, the development of a new high-performance anode material has become a hot topic in lithium-ion battery research.

[0003] Organic electrode materials have attracted widespread attention due to their structural tunability, resource sustainability, environmental friendliness, and renewability. However, the high solubility of small molecule organic electrode materials and linear polymers in organic electrolytes can lead to rapid capacity decay, and the occurrence of side reactions can result in low Coulombic efficiency and poor cycle life. Traditional linear conjugated polymers, due to π-π stacking, form densely packed molecular chains, limiting contact with the electrolyte, thus affecting redox activity. Furthermore, during long-term cycling, the electrode materials may experience structural degradation, which in turn affects cycling stability. Furthermore, the low electronic conductivity of organic electrode materials limits their rate capability. Conjugated microporous polymers (CMPs), a new type of organic porous material, exhibit significant advantages as anode materials for lithium-ion batteries due to their high specific surface area, porous structure, and excellent physicochemical stability. The high specific surface area facilitates the exposure of more redox reaction active sites, thereby increasing specific capacity; the porous structure facilitates electrolyte penetration, shortens lithium ion transport pathways, and improves reaction kinetics; and the excellent stability ensures consistent performance during cycling.

[0004] Therefore, the development of conjugated microporous polymers that are easy to synthesize and have high specific capacity, high rate performance and excellent cycle stability has become a new direction in the research of organic negative electrode materials for lithium-ion batteries. Summary of the Invention

[0005] To address the technical problems existing in the above-mentioned prior art, the present invention provides a novel conjugated microporous polymer, its preparation method, and application. The present invention uses benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide as raw materials, and adopts a reversible Schiff base condensation reaction to synthesize the novel conjugated microporous polymer. The novel conjugated microporous polymer prepared by the present invention has a high specific surface area and a porous structure. As a negative electrode material for lithium-ion batteries, it facilitates electron transfer and ion transport, exhibits excellent electrochemical properties, and has good application prospects in the field of negative electrode materials for lithium-ion batteries.

[0006] To achieve the above object, the present invention provides a novel conjugated microporous polymer having the structural formula shown in formula (I):

[0007] (I)

[0008] The present invention also provides a method for preparing the novel conjugated microporous polymer, comprising the following steps:

[0009] (1) Under the protection of inert gas, add benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide into an organic solvent and heat and stir to react;

[0010] (2) After the reaction is completed, washing, filtering, and drying are performed to obtain the novel conjugated microporous polymer.

[0011] Furthermore, in step (1), the molar ratio of the benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde to dithiooxamide is 1:1-5.

[0012] Furthermore, the organic solvent is N,N-dimethylformamide or N-methylpyrrolidone.

[0013] Furthermore, the heating reaction condition is 100-200 ° C. and stirring the reaction for 24-120 h.

[0014] Furthermore, the inert gas is nitrogen or argon.

[0015] Furthermore, after the reaction is completed, the reaction solution is poured into deionized water and stirred and slurried, and then the mixed solution is filtered, and the filter residue is washed with dichloromethane, ethanol, and water respectively, and vacuum dried at 80-150 ° C to obtain the novel conjugated microporous polymer.

[0016] The present invention also provides the use of the novel conjugated microporous polymer in the negative electrode material of lithium ion batteries.

[0017] Furthermore, the above-mentioned new conjugated microporous polymer is used as an active material, mixed evenly with a conductive agent and a binder in a solvent to form a slurry, and the slurry is evenly coated on a copper foil. After vacuum drying, it is cut into electrodes to be used using a cutting machine; the electrodes are assembled into button batteries with a lithium sheet as a negative electrode, a diaphragm, and an electrolyte in an argon-protected glove box.

[0018] Furthermore, the conductive agent is at least one of acetylene black, Ketjen black, conductive carbon black and carbon nanotubes, the binder is at least one of polyvinylidene fluoride, styrene-butadiene rubber, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid and polyacrylonitrile, and the solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, diethyl ether, ethyl acetate, N-butylpyrrolidone and deionized water.

[0019] Specifically, the electrode preparation process involves the following steps: First, pre-prepared BTSZ is used as the active material, conductive carbon black as the conductive agent, and polyvinylidene fluoride as the binder. The active material, conductive agent, and binder are mixed in a mass ratio of 6:3:1. An appropriate amount of N-methylpyrrolidone is added, and the mixture is ground to form a uniform slurry. The slurry is evenly applied to the surface of copper foil using a scraper and vacuum-dried at 80°C for 12 hours. After drying, the electrode is punched into 10 mm diameter discs using a mold to obtain the electrode.

[0020] The battery assembly includes the following steps: using the prepared electrode as the positive electrode, the metal lithium sheet as the negative electrode, 1MLiClO4 ethylene carbonate (EC): diethyl carbonate (DEC) = 1: 1 (v / v) solution as the electrolyte solution, and a polypropylene microporous membrane (Celgard 2500) as the separator to assemble into a CR2032 button battery.

[0021] The present invention has the following beneficial effects:

[0022] (1) The present invention constructs a conjugated microporous polymer material (BTSZ) with large specific surface area, good chemical stability and excellent thermal stability through reasonable molecular structure design. Specifically, a new conjugated microporous polymer is synthesized by reversible Schiff base condensation reaction using benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide as raw materials. The conjugated microporous polymer material is in the form of spherical particles with a specific surface area of ​​279.4 m 2 g -1The average pore size distribution is around 0.79 nm. As a negative electrode material for lithium-ion batteries, its high specific surface area helps to fully infiltrate the electrolyte, thereby exposing more active sites for more effective redox reactions; and the structural characteristics of the high specific surface area and porous structure of this new conjugated microporous polymer are conducive to electron transfer and ion transport, making it exhibit excellent electrochemical properties, and has good application prospects in the field of negative electrode materials for lithium-ion batteries.

[0023] (2) The present invention uses benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide as raw materials and adopts a reversible Schiff base condensation reaction to synthesize a new conjugated microporous polymer. The conjugated microporous polymer material extends the conjugated structure of thiophene and constructs a conjugated thiophene bridge, in which three thiophene units are fused at the boundary of the benzene ring, resulting in a dihedral angle between adjacent thiophenes of almost zero, which helps to achieve excellent π electron delocalization and thus improve the conductivity. The present invention introduces a thiazolyl[5,4-d]thiazole ring structure, which can serve as an electron acceptor unit and is combined with the conjugated thiophene bridge structure as an electron donor to form an effective electron donor-acceptor system, which can significantly improve its conductivity. At the same time, the thiazolyl[5,4-d]thiazole ring structure can optimize the pore structure of the conjugated microporous polymer and promote ion transport. This invention optimizes the electronic structure of the conjugated microporous polymer by introducing heteroatoms such as N and S, thereby improving its conductivity. The C=N double bond in the molecular structure also enhances molecular stability. By extending the thiophene conjugated structure to create a conjugated thiophene bridge and introducing a thiazo[5,4-d]thiazole ring structure, the conjugated microporous polymer material exhibits excellent electrochemical properties, enhancing its intrinsic conductivity and structural stability. This material has promising application prospects in the field of lithium-ion battery negative electrode materials.

[0024] (3) The present invention synthesizes conjugated microporous polymers with high specific surface area and abundant active sites through molecular design, which can enhance the structural integrity and cycle life of electrode materials. At the same time, by designing conjugated microporous polymers with cross-linked porous skeletons, it can significantly enhance their chemical stability in electrolytes, thus avoiding the problem of rapid capacity decay caused by the high solubility of organic small molecules and linear polymers in organic electrolytes. The new conjugated microporous polymer BTSZ prepared by the present invention is used as a negative electrode material for lithium-ion batteries, which has high specific capacity, good rate performance and excellent cycle stability. When the current density is increased from 0.1 A g -1 Increased to 2 A g -1 When BTSZ showed 1016, 742, 533, 409 and 302 mA h g -1 The high reversible specific capacity; when the current density is restored to 0.1 A g -1 When the BTSZ electrode is able to recover to 982 mA h g-1 The reversible specific capacity has excellent rate performance; at 0.2 A g -1 After 1000 cycles at a current density of 1.5 GHz, BTSZ can still maintain a charge capacity of 820 mA h g -1 It has high reversible specific capacity and excellent electrochemical cycle stability.

[0025] In addition to the above-mentioned objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 The structural formula and synthetic route of conjugated microporous polymer BTSZ;

[0028] Figure 2 is a Fourier transform infrared spectrum of the conjugated microporous polymer BTSZ prepared in Example 2;

[0029] Figure 3 The conjugated microporous polymer BTSZ prepared in Example 2 13 C solid-state NMR spectrum;

[0030] Figure 4 This is a thermogravimetric curve of the conjugated microporous polymer BTSZ prepared in Example 2 under a nitrogen atmosphere;

[0031] Figure 5 is a scanning electron micrograph of the conjugated microporous polymer BTSZ prepared in Example 2;

[0032] Figure 6 is the nitrogen adsorption-desorption curve of the conjugated microporous polymer BTSZ prepared in Example 2;

[0033] Figure 7 is the pore size distribution diagram of the conjugated microporous polymer BTSZ prepared in Example 2;

[0034] Figure 8 This is a rate performance diagram of the conjugated microporous polymer BTSZ as a negative electrode material for lithium-ion batteries in an application example;

[0035] Figure 9 The charge and discharge curves of the conjugated microporous polymer BTSZ used as the negative electrode material of the lithium ion battery in the application example;

[0036] Figure 10This is a graph showing the cycling performance of the conjugated microporous polymer BTSZ as a negative electrode material for lithium-ion batteries in an application example. DETAILED DESCRIPTION

[0037] Below in conjunction with the accompanying drawings in the embodiments of the present invention, the technical scheme in the embodiments of the present invention is clearly and completely described. Obviously, described embodiment is only partial embodiment of the present invention, rather than whole embodiment. Based on the embodiment in the present invention, those of ordinary skill in the art, without making the every other embodiment obtained under the creative work premise, all belong to the scope of protection of the present invention. Unless otherwise stated, the reagent, method and equipment adopted in the present invention are conventional reagents, methods and equipment in the art. Unless otherwise stated, the reagents and materials used in the following examples are commercially available.

[0038] Example 1

[0039] The preparation method of conjugated microporous polymer BTSZ, the specific steps are as follows:

[0040] (1) Under argon atmosphere, 165 mg (0.50 mmol) of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde and 60 mg (0.50 mmol) of dithiooxamide were added to 30 mL of N,N-dimethylformamide and stirred at 200 °C for 24 h.

[0041] (2) After the reaction is completed, the reaction solution is poured into deionized water and stirred, and then the mixed solution is filtered. The filter residue is washed with dichloromethane, ethanol, and water respectively, and vacuum dried at 80 °C to finally obtain a reddish-brown BTSZ powder.

[0042] Example 2

[0043] The preparation method of conjugated microporous polymer BTSZ, the specific steps are as follows:

[0044] (1) Under argon atmosphere, 250 mg (0.76 mmol) of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde and 137 mg (1.14 mmol) of dithiooxamide were added to 40 mL of N,N-dimethylformamide and stirred at 160 °C for 72 h.

[0045] (2) After the reaction is completed, the reaction solution is poured into deionized water and stirred, and then the mixed solution is filtered. The filter residue is washed with dichloromethane, ethanol, and water respectively, and vacuum dried at 100 °C to finally obtain reddish-brown BTSZ powder.

[0046] Example 3

[0047] The preparation method of conjugated microporous polymer BTSZ, the specific steps are as follows:

[0048] (1) Under argon atmosphere, 165 mg (0.50 mmol) of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde and 300 mg (2.50 mmol) of dithiooxamide were added to 50 mL of N,N-dimethylformamide and stirred at 100°C for 120 h.

[0049] (2) After the reaction is completed, the reaction solution is poured into deionized water and stirred, and then the mixed solution is filtered. The filter residue is washed with dichloromethane, ethanol, and water respectively, and vacuum dried at 150 °C to finally obtain reddish-brown BTSZ powder.

[0050] Figure 1 The structural formula and synthetic route of the conjugated microporous polymer BTSZ are presented. The heterocyclic polymer is synthesized via a reversible Schiff base condensation reaction.

[0051] Figure 2 The Fourier transform infrared spectrum of the conjugated microporous polymer BTSZ prepared in Example 2 is shown in FIG. Figure 2 It can be seen that BTSZ is at 1600 cm -1 The characteristic absorption peak of C=N double bond is shown at , while this absorption peak is not observed in the infrared spectrum of benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde (BTT), proving the success of the condensation reaction.

[0052] Figure 3 The conjugated microporous polymer BTSZ prepared in Example 2 13 C solid-state NMR spectrum. Figure 3 It can be seen that the peaks at 130.9 ppm and 137.4 ppm correspond to the aggregated aromatic carbons in the BTT framework, and the peaks at 142.6 ppm and 184.1 ppm correspond to the C=C double bond and C=N double bond of the thiazolo[5,4-d]thiazole ring in the BTSZ structure, respectively, proving the success of the condensation reaction.

[0053] Figure 4 The thermogravimetric curve of the conjugated microporous polymer BTSZ prepared in Example 2 under a nitrogen atmosphere. Figure 4 It can be seen that at 322 °C, the weight of BTSZ only loses 10%, indicating that it has good thermal stability, ensuring its cycle stability and safety as a negative electrode material for lithium-ion batteries during the cycle process.

[0054] Figure 5This is a scanning electron microscope image of the conjugated microporous polymer BTSZ prepared in Example 2. Figure 5 It can be seen that BTSZ is composed of spherical nanoparticles, and this micromorphology can provide high specific surface area and porous structure.

[0055] Figure 6 is the nitrogen adsorption-desorption curve of the conjugated microporous polymer BTSZ prepared in Example 2. Figure 6 It can be seen that the specific surface area of ​​BTSZ is 279.4 m 2 g -1 , its high specific surface area provides more active sites for redox reactions, thus providing high specific capacity.

[0056] Figure 7 The pore size distribution diagram of the conjugated microporous polymer BTSZ prepared in Example 2. Figure 7 Calculations using a nonlocal density functional theory model show that the pore size of BTSZ is primarily distributed around 0.79 nm, exhibiting significant microporous characteristics. Its porous structure facilitates sufficient electrolyte penetration, shortens the lithium ion transport path, and thus improves reaction kinetics and rate performance. The conjugated microporous polymers prepared in Examples 1 and 3 exhibit similar physicochemical properties to those prepared in Example 2 and are not further detailed here.

[0057] Application Examples

[0058] The BTSZ prepared in Example 2 was used as the negative electrode material for a lithium-ion battery to prepare a lithium-ion battery and its electrochemical performance was tested.

[0059] (1) Preparation of the electrode: First, the pre-prepared BTSZ is used as the active material, conductive carbon black as the conductive agent, and polyvinylidene fluoride as the binder. The active material, conductive agent, and binder are mixed in a mass ratio of 6:3:1, and an appropriate amount of N-methylpyrrolidone is added. The mixture is ground to form a uniform slurry. The slurry is evenly coated on the surface of the copper foil using a scraper and vacuum dried at 80°C for 12 h. After drying, it is punched into a 10 mm diameter disc using a mold to obtain the electrode.

[0060] (2) Assembly of lithium-ion batteries: CR2032 button-type batteries were assembled in an argon-filled glove box (O2 ≤ 0.01 ppm, H2O ≤ 0.01 ppm) using the prepared electrode as the positive electrode, the metal lithium sheet as the negative electrode, a 1M LiClO4 solution of ethylene carbonate (EC): diethyl carbonate (DEC) = 1:1 (v / v) as the electrolyte solution, and a polypropylene microporous membrane (Celgard 2500) as the separator.

[0061] (3) Electrochemical performance test of lithium-ion batteries: Conduct electrochemical tests on the prepared lithium-ion batteries.

[0062] Figure 8 The conjugated microporous polymer BTSZ is used as the rate performance of the negative electrode material of lithium ion batteries. Figure 8 It can be seen that when the current density increases from 0.1 A g -1 Increased to 2 A g -1 When BTSZ showed 1016, 742, 533, 409 and 302 mA h g -1 When the current density returns to 0.1 A g -1 When the BTSZ electrode is able to recover to 982 mAh g -1 The reversible specific capacity shows that it has excellent rate performance.

[0063] Figure 9 The charge-discharge curves of the conjugated microporous polymer BTSZ as a negative electrode material for lithium-ion batteries at different current densities are shown in the following examples. Although the overpotential increases with increasing current density, the charge-discharge curves at different current densities are essentially similar.

[0064] Figure 10 The cycling performance of conjugated microporous polymer BTSZ as negative electrode material for lithium ion batteries is shown in the following application examples. Figure 10 It can be seen that at 0.2 A g -1 After 1000 cycles at a current density of 1.5 GHz, BTSZ can still maintain a charge capacity of 820 mA h g -1 The high reversible specific capacity indicates excellent electrochemical cycling stability. The electrochemical performance of lithium-ion batteries prepared using the BTSZ prepared in Examples 1 and 3 as the negative electrode material for lithium-ion batteries is similar to that of the lithium-ion battery prepared using the BTSZ prepared in Example 2 as the negative electrode material for lithium-ion batteries, and will not be repeated here.

[0065] In summary, the present invention uses benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide as raw materials to synthesize a conjugated microporous organic polymer BTSZ in a single step via a reversible Schiff base condensation reaction. This material consists of spherical nanoparticles. From a microscopic perspective, this structure not only increases the specific surface area and redox active sites, thereby providing a high specific capacity, but also its porous structure promotes sufficient electrolyte penetration and shortens the lithium ion transport path, thereby improving reaction kinetics and rate performance.

[0066] In addition, the present invention uses benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide as raw materials and adopts a reversible Schiff base condensation reaction to synthesize a new type of conjugated microporous polymer. The conjugated microporous polymer material extends the conjugated structure of thiophene and constructs a conjugated thiophene bridge, in which three thiophene units are fused at the boundary of the benzene ring, resulting in a dihedral angle between adjacent thiophenes of almost zero, which helps to achieve superior π electron delocalization and thus improve conductivity. The present invention introduces a thiazolyl[5,4-d]thiazole ring structure, which can serve as an electron acceptor unit and is combined with a conjugated thiophene bridge structure as an electron donor to form an effective electron donor-acceptor system, which can significantly improve its conductivity. At the same time, the thiazolyl[5,4-d]thiazole ring structure can optimize the pore structure of the conjugated microporous polymer and promote ion transport. This invention optimizes the electronic structure of the conjugated microporous polymer by introducing heteroatoms such as N and S, thereby improving its conductivity. The C=N double bond in the molecular structure also enhances molecular stability. By extending the thiophene conjugated structure to create a conjugated thiophene bridge and introducing a thiazo[5,4-d]thiazole ring structure, the conjugated microporous polymer material exhibits excellent electrochemical properties, enhancing its intrinsic conductivity and structural stability. This material has promising application prospects in the field of lithium-ion battery negative electrode materials.

[0067] This invention synthesizes conjugated microporous polymers with high specific surface area and abundant active sites through molecular design, which can enhance the structural integrity and cycle life of electrode materials. Simultaneously, by designing a conjugated microporous polymer with a cross-linked porous skeleton, its chemical stability in electrolytes can be significantly enhanced, thus avoiding the problem of rapid capacity decay caused by the high solubility of small organic molecules and linear polymers in organic electrolytes. The novel conjugated microporous polymer BTSZ prepared by this invention, when used as a negative electrode material for lithium-ion batteries, exhibits high specific capacity, good rate performance, and excellent cycle stability, and has promising application prospects in the field of negative electrode materials for lithium-ion batteries.

[0068] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. Application of a conjugated microporous polymer in a negative electrode material for a lithium ion battery, characterized in that: The conjugated microporous polymer has the structural formula shown in formula (I): （Ⅰ） A conjugated microporous polymer is used as an active material, mixed evenly with a conductive agent and a binder in a solvent to form a slurry, which is evenly coated on a copper foil. After vacuum drying, the slurry is cut into electrodes to be used using a cutting machine. The electrodes are assembled into button batteries with a lithium sheet as the negative electrode, a separator, and an electrolyte in an argon-protected glove box.

2. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 1, characterized in that: The preparation method of the conjugated microporous polymer comprises the following steps: (1) Under the protection of inert gas, add benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde and dithiooxamide into an organic solvent and heat and stir to react; (2) After the reaction is completed, washing, filtering, and drying are performed to obtain the conjugated microporous polymer.

3. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 2, characterized in that: In step (1), the molar ratio of the benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-trialdehyde to dithiooxamide is 1:1-5.

4. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 2, characterized in that: In step (1), the organic solvent is N,N-dimethylformamide or N-methylpyrrolidone.

5. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 2, characterized in that: In step (1), the heating and stirring reaction conditions are 100-200 °C and stirring reaction for 24-120 h.

6. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 2, characterized in that: In step (1), the inert gas is nitrogen or argon.

7. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 2, characterized in that: In step (2), after the reaction is completed, the reaction solution is poured into deionized water and stirred and slurried, and then the mixed solution is filtered, and the filter residue is washed with dichloromethane, ethanol, and water respectively, and vacuum dried at 80-150 ° C to obtain the conjugated microporous polymer.

8. The use of a conjugated microporous polymer in a negative electrode material for a lithium ion battery according to claim 1, characterized in that: The conductive agent is at least one of conductive carbon black and carbon nanotubes, the binder is at least one of polyvinylidene fluoride, styrene-butadiene rubber, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid and polyacrylonitrile, and the solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, diethyl ether, ethyl acetate, N-butylpyrrolidone and deionized water.

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