Cross-linked conjugated polymer, preparation method thereof and application of cross-linked conjugated polymer in alkali metal battery

Abstract

The invention belongs to the technical field of battery positive electrode material preparation, and particularly relates to a cross-linked conjugated polymer, a preparation method and application in an alkali metal battery. When the cross-linked conjugated polymer is used as a positive electrode, the cross-linked conjugated polymer shows excellent performance in lithium, sodium and potassium ion batteries: the average discharge voltage is as high as 3.4-3.5 V, which is beneficial for improving the energy density of the battery; under extremely high current density, high capacity exceeding 120mAh. G <-1 > can still be released, and extremely fast dynamic characteristics are shown; and under the harsh test condition, the capacity retention ratio still reaches up to 85%-90%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery positive electrode material preparation, and particularly relates to a crosslinked conjugated polymer, a preparation method and application thereof in alkali metal batteries. BACKGROUND

[0002] With the rapid growth of global demand for sustainable energy and large-scale energy storage technology, the development of high-performance secondary battery systems has become a core challenge in the energy field. Current commercial lithium-ion batteries generally use inorganic transition metal oxides (such as lithium cobaltate, lithium iron phosphate and ternary materials) as positive electrode materials, which have made certain breakthroughs in energy density and cycle stability. However, such inorganic materials face two major bottlenecks: first, the uneven distribution of key elements such as cobalt and lithium poses regional limitations and price fluctuation risks, restricting large-scale application; second, the rigid crystal structure of the inorganic material has low tolerance to the volume change of ion intercalation / deintercalation, and has poor compatibility with larger size alkali metal ions (such as Na + , K + ) or multivalent ions (such as Zn 2+ , Mg 2+ ), which makes it difficult to meet the development needs of the next generation of low-cost and diversified battery systems.

[0003] To overcome the inherent defects of inorganic materials, organic electrode materials have become a research hotspot for the next generation of electrode materials due to their unique advantages. Compared with inorganic materials, organic electrode materials are composed of abundant elements such as C, H, O and N, have the characteristics of abundant resources, high theoretical specific capacity, strong structural designability, environmental friendliness and excellent mechanical flexibility, and are particularly suitable for low-cost and high-safety battery systems. Among them, p-type organic materials containing N-heterocycles (such as triphenylamine derivatives and phenazine derivatives) are considered to be one of the most promising positive electrode materials because they can achieve a working voltage as high as 3.5V (vs. Li / Li + ).

[0004] Although p-type organic materials show high voltage potential, their actual application still faces the inherent contradiction between structure and performance: small molecule active substances (such as triphenylamine and phenazine monomers) and their oxidation-reduction products have high solubility in organic electrolyte, resulting in serious loss of active substances and rapid decline of battery cycle life. To solve the solubility problem, researchers have polymerized active monomers into linear polymers, which can reduce solubility, but the tight packing and disordered entanglement of linear chains will hinder the infiltration and access of electrolyte to the internal oxidation-reduction active sites, resulting in tortuous ion diffusion paths and low utilization rate of active sites, and the actual specific capacity is generally lower than 100mAh·g -1, and the rate performance is poor. Therefore, it is necessary to develop an organic positive electrode material that can simultaneously solve the bottlenecks of the solubility problem and the low active site utilization of organic materials, and cooperatively achieve high working voltage, high specific capacity, excellent rate performance and ultra-long cycle stability. SUMMARY

[0005] The purpose of the present application is to provide a cross-linked conjugated polymer and a preparation method and application in alkali metal batteries, aiming to overcome the contradiction between the solubility problem and the low active site utilization of the organic positive electrode material in the prior art, and achieve the cooperative unity of high voltage, high capacity, high rate and long cycle performance.

[0006] In order to achieve the above-mentioned purpose, the present application can adopt the following technical solutions: The present application provides a cross-linked conjugated polymer, and the structural formula is as follows: , wherein n is an integer of 20-93.

[0007] The present application provides a preparation method of the cross-linked conjugated polymer, and the preparation method comprises: coupling polymerization reaction of N1,N1,N4,N4-tetra(4-bromophenyl)benzene-1,4-diamine and 5,10-dihydrophenazine to obtain the cross-linked conjugated polymer.

[0008] Preferably, in the above preparation method, the coupling polymerization reaction is Buchwald-Hartwig aryl amination reaction.

[0009] More preferably, the Buchwald-Hartwig aryl amination reaction satisfies any one or more of the following conditions: (i) the catalytic system of the Buchwald-Hartwig aryl amination reaction is a palladium catalytic system; (ii) based on (i), the palladium catalytic system comprises a palladium source and a phosphine ligand; (iii) based on (i), the reaction is carried out under strong base conditions; (iv) based on (i), the reaction temperature is 80°C-130°C.

[0010] More preferably, in the above preparation method, (ii) the palladium source is selected from one or more combinations of tris(dibenzylideneacetone)dipalladium(0) or [2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl]palladium(II) chloride or tetrakis(triphenylphosphine)palladium; (ii) the phosphine ligand is selected from one or more combinations of 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl or 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl. The strong base in (iii) is selected from one or more combinations of sodium tert-butoxide, sodium methoxide or triethylamine.

[0011] In still another aspect, the present application provides a positive electrode material for alkali metal batteries, comprising the cross-linked conjugated polymer as described above.

[0012] Preferably, in the positive electrode material for alkali metal batteries as described above, the positive electrode material for alkali metal batteries comprises the cross-linked conjugated polymer, conductive carbon and polyvinylidene fluoride in a mass ratio of (5.5-6.5):(2.5-3.5):1.

[0013] In still another aspect, the present application provides a positive electrode sheet for alkali metal batteries, prepared from the positive electrode material for alkali metal batteries as described above.

[0014] In still another aspect, the present application provides an alkali metal battery comprising the positive electrode sheet for alkali metal batteries as described above.

[0015] Preferably, the alkali metal battery as described above is an alkali metal half battery or an alkali metal full battery.

[0016] Preferably, the alkali metal battery as described above is a lithium ion battery, a sodium ion battery or a potassium ion battery.

[0017] In still another aspect, the present application provides a use of the cross-linked conjugated polymer as described above as a positive electrode active material for alkali metal batteries.

[0018] Preferably, in the use as described above, the alkali metal battery is a lithium ion battery, a sodium ion battery or a potassium ion battery.

[0019] The present application has at least the following advantages: (1) The cross-linked conjugated polymer provided by the present application overcomes the contradiction between the solubility problem and the low active site utilization rate of the existing organic positive electrode material, and realizes the synergistic unification of high voltage, high capacity, high rate and long cycle performance. Specifically, the battery constructed by the present application can be cycled for 50,000 times, which indicates that it is not dissolved in the electrolyte and can achieve a discharge capacity of 130 mAh·g -1 , which indicates that the active sites are fully utilized; (2) The cross-linked conjugated polymer provided by the present application as a positive electrode exhibits excellent performance in lithium, sodium and potassium ion batteries: high working voltage: the average discharge voltage is as high as 3.4V-3.5V, which is beneficial to improve the energy density of the battery; high specific capacity and high rate performance: even at a very high current density (for example, as high as 10 A·g -1 in a sodium battery, about 50C), more than 120 mAh·g -1high capacity, showing extremely fast kinetic characteristics; ultra-long cycle life: the capacity retention rate is still as high as 85%-90% under severe test conditions (for example, the sodium battery is cycled 50,000 times at 10 A·g -1 -1, and the lithium battery is cycled 30,000 times at 10 A·g -1 -1), which is better than the reported organic electrode materials; for example, the average discharge potential of the PTCDI-DAQ polymer is 1.7 V, the initial discharge capacity is 203 mAh·g -1 -1 at a current density of 100 mA·g -1 -1, only 121 mAh·g -1 -1 remains after 100 times, and the capacity retention rate is only 60%; the average discharge potential of the PVDMP polymer is 3.2 V, but the capacity retention rate is only 68% after 4,000 cycles at a current density of 5 C; (3) The preparation method of the cross-linked conjugated polymer is simple, efficient, has strong universality, is relatively mild, and has high total yield, thereby providing a feasible way for the large-scale preparation of the cross-linked conjugated polymer. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a synthesis schematic diagram of the cross-linked conjugated polymer TP-PZ; Figure 2 is an infrared spectrum diagram of the cross-linked conjugated polymer TP-PZ and related raw materials; Figure 3 is a solid-state nuclear magnetic resonance carbon spectrum diagram of the cross-linked conjugated polymer TP-PZ; Figure 4 is a gel permeation chromatogram of the cross-linked conjugated polymer TP-PZ; Figure 5 is a CV curve diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a lithium half-cell; Figure 6 is a cycle performance diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a lithium half-cell; Figure 7 is a charge-discharge curve diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a lithium half-cell; Figure 8 is a CV curve diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a sodium half-cell; Figure 9 is a cycle performance diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a sodium half-cell; Figure 10 is a charge-discharge curve diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a sodium half-cell; Figure 11 is a CV curve diagram of the positive electrode of the cross-linked conjugated polymer TP-PZ in a potassium half-cell; Figure 12 Cycling performance of the cross-linked conjugated polymer TP-PZ cathode in potassium half-cell; Figure 13 Charge-discharge curves of the cross-linked conjugated polymer TP-PZ cathode in potassium half-cell; Figure 14 Cycling performance of the sodium full-cell assembled by the cross-linked conjugated polymer TP-PZ cathode and hard carbon anode. DETAILED DESCRIPTION

[0021] The embodiments are provided for better illustrating the present application, but are not intended to limit the present application to the embodiments only. Therefore, the skilled in the art can make non-essential improvements and adjustments to the embodiments according to the above disclosure, which still fall within the protection scope of the present application.

[0022] The terms used herein are used only to describe specific embodiments, and are not intended to limit the present disclosure. Unless there is a clear different meaning in the context, the expression of the singular includes the expression of the plural. As used herein, it is understood that terms such as "include", "have", "contain", etc. are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials or combinations. The terms of the present application are disclosed in the specification, and are not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials or combinations can exist or can be added. As used herein, " / " can be interpreted as "and" or "or" depending on the circumstances.

[0023] In a first aspect, the embodiments of the present application provide a cross-linked conjugated polymer, the structural formula of which is as follows: wherein n is an integer of 20-93.

[0024] It should be noted that the three-dimensional covalent cross-linked network structure designed by the present application fundamentally solves the "dissolution-performance" paradox of organic electrode materials. Specifically, on the one hand, the insoluble polymer network formed by covalent bonds effectively inhibits the dissolution and shuttling of active materials in electrolyte, ensuring ultra-high cycle stability; on the other hand, the highly cross-linked and hyperbranched topological structure forms a loose skeleton rich in pores at the micro level, providing three-dimensional channels for the full infiltration of electrolyte and the rapid transmission of ions, so that the high-density redox active sites (triphenylamine and phenazine units) inside the network can be efficiently utilized, thereby realizing high specific capacity.

[0025] It should be further noted that the cross-linked conjugated polymer combines the advantages of triphenylamine units (p-type, contributing high voltage plateau) and phenazine units (p-type, contributing multi-electron transfer). As a positive electrode, the cross-linked conjugated polymer exhibits excellent performance in lithium, sodium and potassium ion batteries: high working voltage: the average discharge voltage is as high as 3.4V-3.5V, which is beneficial to improve the energy density of the battery; high specific capacity and high rate performance: even at very high current density (for example, as high as 10A·g -1 , even 50C), a high capacity of more than 120mAh·g -1 can still be released, showing extremely fast kinetic characteristics; ultra-long cycle life: under severe test conditions (for example, sodium battery at 10A·g -1 for 50000 cycles, lithium battery at 50C for 3000 cycles), the capacity retention rate is still as high as 85%-90%. As can be seen from the above, the cross-linked conjugated polymer exhibits excellent performance in lithium, sodium and potassium three mainstream alkali metal ion batteries, showing its great potential as a “universal” high-performance organic positive electrode platform.

[0026] It should be further noted that the cross-linked conjugated polymer structural unit in the present application can be represented by the following general formula: [(TPA-core)]m[(PZ-linker)]n;wherein, TPA-core represents a tetravalent cross-linking center unit derived from N1,N1,N4,N4-tetrakis(4-halophenyl)benzene-1,4-diamine; PZ-linker represents a divalent bridging unit derived from 5,10-dihydrophenazine; m and n are the degree of polymerization, representing the stoichiometric ratio of the two units in the polymer network.

[0027] In a second aspect, the present application provides a preparation method of the above cross-linked conjugated polymer, the preparation method comprising: coupling and polymerizing N1,N1,N4,N4-tetrakis(4-bromophenyl)benzene-1,4-diamine and 5,10-dihydrophenazine to obtain the cross-linked conjugated polymer.

[0028] It should be noted that the preparation method of the cross-linked conjugated polymer provided by the present application is simple, efficient, strong in universality, relatively mild in conditions, and high in total yield, which provides a feasible way for the large-scale preparation of the cross-linked conjugated polymer.

[0029] In some specific examples, in the above preparation method, the coupling and polymerization reaction is a Buchwald-Hartwig aryl amination reaction.

[0030] It should be noted that the coupling polymerization reaction is all the reactions that can realize the coupling polymerization known in the art, and the Buchwald-Hartwig aryl amination reaction can be preferentially selected in the present application. In addition, the Buchwald-Hartwig aryl amination reaction is known in the art.

[0031] In some specific examples, the Buchwald-Hartwig aryl amination reaction described above satisfies any one or more of the following conditions: (i) The catalytic system of the Buchwald-Hartwig aryl amination reaction is selected from a palladium catalytic system; specifically, the catalytic system of the Buchwald-Hartwig aryl amination reaction in the present application can preferentially select a palladium catalytic system, which is more suitable for the preparation of the cross-linked conjugated polymer in the present application; (ii) Based on (i), the palladium catalytic system comprises a palladium source and a phosphine ligand; specifically, the palladium catalytic system is known in the art; (iii) Based on (i), the reaction is carried out under strong base conditions; (iv) Based on (i), the reaction temperature is 80°C to 130°C, such as 90°C, 100°C, 110°C or 120°C, etc.

[0032] In some specific examples, in the preparation method described above, (ii) The palladium source is selected from one or more combinations of tris(dibenzylideneacetone)dipalladium(0) or [2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl] palladium (II) chloride or tetraphenylphosphine palladium; (ii) The phosphine ligand is selected from one or more combinations of 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl or 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl; (iii) The strong base is selected from one or more combinations of sodium tert-butoxide, sodium methoxide or triethylamine.

[0033] In a third aspect, the embodiments of the present application provide a positive electrode material for an alkali metal battery, which comprises the cross-linked conjugated polymer described above.

[0034] It should be noted that the cross-linked conjugated polymer in the present application can be added with other auxiliary materials to prepare the positive electrode material for an alkali metal battery.

[0035] In some specific examples, in the positive electrode material for an alkali metal battery described above, the positive electrode material for an alkali metal battery comprises the cross-linked conjugated polymer, conductive carbon and polyvinylidene fluoride, and the mass ratio is (5.5-6.5):(2.5-3.5):1.

[0036] It should be noted that the other auxiliary materials can be conductive carbon and polyvinylidene fluoride, and the mass ratio of the conductive carbon and the polyvinylidene fluoride can be preferably (5.5-6.5):(2.5-3.5):1. In addition, it should be understood that the alkali metal battery positive electrode material can further include a solvent, which is well known in the art, such as NMP (methyl pyrrolidone).

[0037] In a fourth aspect, the embodiments of the present application provide an alkali metal battery positive electrode sheet prepared from the alkali metal battery positive electrode material described above.

[0038] It should be noted that the alkali metal battery positive electrode material in the present application can be coated on the current collector (such as an aluminum foil current collector) after homogenization to obtain an alkali metal battery positive electrode sheet after drying.

[0039] In a fifth aspect, the embodiments of the present application provide an alkali metal battery including the alkali metal battery positive electrode sheet described above.

[0040] It should be noted that the alkali metal battery positive electrode sheet in the present application can be assembled with an alkali metal battery negative electrode and an electrolyte to obtain an alkali metal battery. In addition, the alkali metal battery negative electrode and the electrolyte are well known in the art.

[0041] In some specific examples, the alkali metal battery described above is an alkali metal half-cell or an alkali metal full-cell.

[0042] It should be noted that the alkali metal battery positive electrode sheet in the present application is suitable for an alkali metal half-cell or an alkali metal full-cell, which can be selected according to actual conditions.

[0043] In some specific examples, the alkali metal battery described above is a lithium ion battery, a sodium ion battery, or a potassium ion battery.

[0044] It should be noted that the alkali metal battery in the present application includes but is not limited to a lithium ion battery, a sodium ion battery, or a potassium ion battery.

[0045] In a sixth aspect, the embodiments of the present application provide a use of the cross-linked conjugated polymer described above as an alkali metal battery positive electrode active material.

[0046] It should be noted that the cross-linked conjugated polymer in the present application can be used as an active material of an alkali metal battery positive electrode, which has excellent electrochemical performance when used as an alkali metal battery positive electrode active material.

[0047] In some specific examples, in the use described above, the alkali metal battery is a lithium ion battery, a sodium ion battery, or a potassium ion battery.

[0048] It should be noted that the alkali metal battery in the present application includes but is not limited to a lithium ion battery, a sodium ion battery, or a potassium ion battery.

[0049] In order to better understand the present application, the content of the present application is further illustrated below in combination with specific examples, but the content of the present application is not limited only to the following examples.

[0050] Preparation Examples Example 1 The present application provides a cross-linked conjugated polymer (TP-PZ) and a preparation method thereof.

[0051] (1) Preparation of intermediate N1, N1, N4, N4-tetra(4-bromophenyl)benzene-1, 4-diamine (TP-2Br) (1-1) In a 500 mL round-bottom flask, N1, N1, N4, N4-tetraphenyl-1, 4-benzenediamine (1 mmol, 488.6 mg) was added, followed by 50 mL of dichloromethane (CH2Cl2) as a solvent, and magnetic stirring was performed to dissolve it; (1-2) At room temperature (25°C), N-bromosuccinimide (NBS, 4 mmol, 712.0 mg) was added to the solution in four portions, 1 mmol each, with an interval of 15 minutes between each addition; (1-3) After the addition was completed, the reaction mixture was continuously stirred at room temperature for 8 hours to ensure that the bromination reaction was fully carried out; (1-4) After the reaction was completed, the solvent dichloromethane was removed by rotary evaporation to obtain a crude product; (1-5) The crude product was washed with deionized water several times, then filtered, and vacuum dried at 60°C for 12h, and finally the pure product in the form of white powder was obtained, which was N1, N1, N4, N4-tetra(4-bromophenyl)benzene-1, 4-diamine, with a yield of up to 95%.

[0052] (2) Preparation of cross-linked conjugated polymer (TP-PZ) (2-1) Under strict anhydrous and anaerobic conditions (operated in an argon-filled glove box), N1, N1, N4, N4-tetra(4-bromophenyl)benzene-1, 4-diamine (0.6 mmol, 482.5 mg) prepared above, 5, 10-dihydrophenazine (PZ, 1 mmol, 182.2 mg), sodium tert-butoxide (NaOtBu, 2.2 mmol, 211.4 mg), tris(dibenzylideneacetone)dipalladium (0) (Pd2(dba)3, 0.06 mmol, 54.9 mg), and 2-dicyclohexylphosphino-2', 4', 6'-triisopropyl biphenyl (XPhos, 0.24 mmol, 113.2 mg) were sequentially added to a dry pressure-resistant reaction tube; then, 30 mL of ultradry toluene was added as a solvent; (2-2) Seal the reaction tube, transfer it out of the glove box, place it in an oil bath and heat it to 110°C, and stir it magnetically for 24 hours; (2-3) After the reaction is complete, the system is cooled to room temperature, at which point a large amount of solid precipitate is formed; (2-4) The solid product was collected by vacuum filtration and washed thoroughly with toluene, deionized water and ethanol in sequence to remove residual reactants, catalyst and inorganic salts; (2-5) Dry the washed solid in a vacuum oven; (2-6) Place the dried crude product in a Soxhlet extractor and use tetrahydrofuran (THF) as the extraction solvent for 24 hours of Soxhlet extraction to completely remove all soluble oligomers and impurities; (2-7) After extraction, the insoluble solids were collected and dried under vacuum to obtain the final product—a gray powder of cross-linked conjugated polymer TP-PZ (hereinafter also referred to as TP-PZ polymer), totaling 491.4 mg with a yield of 90%.

[0053] Example 2 This invention provides a TP-PZ positive electrode sheet and its preparation method.

[0054] The TP-PZ prepared in Example 1 was mixed with conductive carbon and PVDF (polyvinylidene fluoride, model: HSV900, molecular weight about 1 million) in a mass ratio of 6:3:1. The mixture was manually ground until the particle size was uniform and there was no obvious particle feel. Then, 500 μL of NMP (methylpyrrolidone) solvent was added to prepare an electrode slurry. The electrode slurry was then uniformly coated on an aluminum foil current collector, dried under vacuum at 70°C, and cut into circular electrodes with a diameter of 12 mm. The electrodes were then placed in a glove box for later use.

[0055] Example 3 This invention provides a lithium-ion half-cell based on the TP-PZ cathode prepared in Example 2 and its assembly process.

[0056] Battery assembly was carried out in an argon-filled glove box, specifically including: using a 2032 type button cell casing, with the TP-PZ electrode prepared in Example 2 as the working electrode (positive electrode), a lithium metal sheet as the counter electrode and reference electrode, and a glass fiber separator (Whatman GF / D) (Suzhou Duoduo Chemical Technology Co., Ltd.) as the separator; the electrolyte was 1M LiPF6 (lithium hexafluorophosphate) dissolved in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) (volume ratio 1:1:1); the assembly was carried out in the order of negative electrode casing - lithium metal sheet - separator - electrolyte - TP-PZ positive electrode - positive electrode casing, and the battery was sealed using a sealing machine to obtain a lithium-ion half cell; the assembled lithium-ion half cell was left to stand at room temperature for 6 hours to ensure that the electrolyte fully wetted the electrodes and separator.

[0057] Example 4 This invention provides a sodium-ion half-cell based on the TP-PZ cathode prepared in Example 2 and its assembly process.

[0058] The battery assembly was carried out in an argon-filled glove box, specifically including: using a 2032 type button cell casing, using the TP-PZ electrode prepared in Example 2 as the working electrode (positive electrode), a sodium metal sheet as the counter electrode and reference electrode, and a glass fiber membrane (Whatman GF / D) as the separator; the electrolyte was 1M NaPF6 (sodium hexafluorophosphate) dissolved in propylene carbonate (PC); the assembly was carried out in the order of negative electrode casing - sodium metal sheet - separator - electrolyte - TP-PZ positive electrode - positive electrode casing, and the battery was sealed using a sealing machine to obtain a sodium-ion half cell; the assembled sodium-ion half cell was left to stand at room temperature for 6 hours to ensure that the electrolyte fully wetted the electrodes and separator.

[0059] Example 5 This invention provides a potassium-ion half-cell based on the TP-PZ cathode prepared in Example 2 and its assembly process.

[0060] The battery assembly was carried out in an argon-filled glove box, specifically including: using a 2032 type button cell casing, using the TP-PZ electrode prepared in Example 2 as the working electrode (positive electrode), a potassium metal sheet as the counter electrode and reference electrode, and a glass fiber membrane (Whatman GF / D) as the separator; the electrolyte was 1M KPF6 (potassium hexafluorophosphate) dissolved in propylene carbonate (PC); the assembly was carried out in the order of negative electrode casing - potassium metal sheet - separator - electrolyte - TP-PZ positive electrode - positive electrode casing, and the battery was sealed using a sealing machine to obtain a potassium-ion half cell; the assembled potassium-ion half cell was left to stand at room temperature for 6 hours to ensure that the electrolyte fully wetted the electrode and separator.

[0061] Example 6 This invention provides a sodium-ion full cell based on the TP-PZ positive electrode prepared in Example 2 and hard carbon as the negative electrode, as well as the assembly process.

[0062] (1) Preparation of hard carbon anode: Commercial hard carbon powder (Kuraray, Japan) was mixed with conductive carbon (Super P) and polyvinylidene fluoride (PVDF) binder at a mass ratio of 8:1:1, and then 500 μL of N-methylpyrrolidone (NMP) solvent was added to prepare a uniform slurry; the slurry was coated on copper foil current collector, and the active material loading was controlled to be approximately (2-3) mg·cm⁻¹. -2 After drying in a vacuum oven at 70°C for 12 hours, the electrodes are cut into circular plates (hard carbon negative electrodes) with a diameter of 12 mm for later use.

[0063] (2) Full cell assembly: The full cell was assembled in an argon-filled glove box (in order for the full cell to work properly, the capacity of the positive and negative electrodes needs to be matched. According to the specific capacity of the TP-PZ positive electrode and the hard carbon negative electrode, the mass ratio of the active materials of the positive and negative electrodes is controlled so that the capacity of the negative electrode is slightly excessive (N / P ratio is about 1.2)). Specifically, it includes: using a 2032 type button cell case, using the TP-PZ electrode prepared in Example 2 as the positive electrode, the hard carbon electrode prepared above as the negative electrode, the glass fiber membrane (Whatman GF / D) as the separator, and 1M NaPF6 (sodium hexafluorophosphate) dissolved in propylene carbonate (PC) as the electrolyte; assembling in the order of negative electrode case-hard carbon negative electrode-separator-electrolyte-TP-PZ positive electrode-positive electrode case, and sealing the battery with a sealing machine to obtain a sodium-ion full cell (also called TP-PZ / / hard carbon sodium-ion full cell); the assembled sodium-ion full cell was tested after standing at room temperature for 6 hours.

[0064] Characterization test In the infrared spectrum (see) Figure 2 The intermediate TP-2Br prepared in Example 1 was heated at 550 cm⁻¹. -1 A distinct C-Br infrared signal peak appeared at 3300 cm⁻¹ (the C-Br stretching vibration peak completely disappeared); PZ showed a peak at 3300 cm⁻¹. -1 There is a distinct stretching vibration peak of NH at 1500 cm⁻¹ (the stretching vibration peak also completely disappears). -1 ~1600cm -1 A distinct aromatic ring skeletal vibration peak appears in the region, at 1280 cm⁻¹. -1The C-Br and NH stretching vibration peaks appeared nearby; while in the product TP-PZ prepared in Example 1, the C-Br and NH stretching vibration peaks disappeared, and only the infrared absorption peaks of the benzene ring skeleton and CN were obvious, indicating that the Buchwald-Hartwig coupling reaction was fully carried out and the reactants were completely converted into supramolecular polymers.

[0065] In addition, the solid-state carbon NMR spectrum of the product (see...) Figure 3 The presence of five distinct C signal peaks in the chromatogram corresponds to carbon atoms in five different chemical environments within the polymer structure. The chemical shifts of these peaks perfectly match the expected polymer structure, further confirming the successful synthesis of the cross-linked conjugated polymer TP-PZ. Furthermore, the carbon atoms in the structure are clearly labeled with their corresponding signal peaks in the solid-state carbon NMR spectrum, fully demonstrating the successful synthesis of the TP-PZ polymer.

[0066] In addition, to investigate the degree of polymerization of pTPPZ polymer, gel permeation chromatography was performed (high-temperature GPC: PL-GPC 20; instrument: Waters 1525; detector: Waters 2414; mobile phase: trichlorobenzene; temperature: 150℃; column: PLgelOlexis 300*7.5mm). The results are as follows: Figure 4 As shown, the molecular weight distribution of p-CZPDPZ is mainly concentrated in the range of 14,000 Daltons to 61,000 Daltons, accounting for 63% of the total weight distribution. The calculated number-average molecular weight (Mn = 19,000 Daltons) and weight-average molecular weight (Mw = 38,000 Daltons) indicate that the polydispersity index (PDI) of p-CZPDPZ is 2.0.

[0067] Performance testing (I) Electrochemical performance test of the lithium-ion half-cell assembled in Example 3 (1) Cyclic voltammetry test Cyclic voltammetry (CV) tests were performed on the assembled lithium-ion half-cell (hereinafter referred to as lithium half-cell) using a Donghua CH7003B electrochemical workstation at a scan rate of 0.1 mV·s. -1 The voltage window is (2.0~4.1)V (vs. Li / Li). + The result is as follows: Figure 5 As shown in the results, the CV curves show that in the first scan, the oxidation peak is located at approximately 3.6 V and the reduction peak is located at approximately 3.4 V, corresponding to the redox reactions of the triphenylamine and phenazine units in the TP-PZ polymer. In the second and third scans, the positions and intensities of the redox peaks remain essentially unchanged, indicating that the material has good electrochemical reversibility.

[0068] (2) Constant current charge and discharge test The lithium half-cell was subjected to constant current charge-discharge testing using the Xinwei Battery Testing System MHW-100-2-160CH. Cycle performance was as follows: Figure 6 As shown, the results indicate that at 1 A·g -1 At a current density of 124 mAh·g, the first-cycle discharge specific capacity reached 124 mAh·g. -1 The charging specific capacity is 120mAh·g -1 The initial coulombic efficiency was 96.8%; after 1500 cycles, the discharge specific capacity remained at 110 mAh·g. -1 The capacity retention rate is as high as 89%, and the coulomb efficiency remains above 99% throughout the cycle.

[0069] In addition, the charge-discharge curves are as follows Figure 7 As shown in the charge-discharge curves, the average discharge voltage of this material is approximately 3.5V (vs. Li / Li). + The flat and highly overlapping charge-discharge plateau indicates that it has excellent electrochemical reversibility and stability.

[0070] As can be seen from the above, TP-PZ polymer, as a cathode material for lithium-ion batteries, exhibits high operating voltage (3.5V) and high specific capacity (124mAh·g). -1 With its excellent combined performance of long cycle life (89% capacity retention after 1500 cycles), it effectively solves the problems of unstable cycling, low voltage, and poor rate performance of organic electrodes in lithium batteries.

[0071] (II) Electrochemical performance testing of the sodium-ion half-cell prepared in Example 4 (1) Cyclic voltammetry test Cyclic voltammetry (CV) tests were performed on the assembled sodium half-cell using an electrochemical workstation at a scan rate of 0.1 mV·s. -1 The voltage window is (2.0~4.1)V (vs. Na / Na). + The result is as follows: Figure 8 As shown in the CV curves, it can be observed that in the first scan, the oxidation peak is located at approximately 3.5 V and the reduction peak is located at approximately 3.3 V. In the second scan, the positions and shapes of the oxidation and reduction peaks remain basically consistent, indicating that the material also has good electrochemical reversibility in sodium-ion batteries.

[0072] (2) Constant current charge and discharge test The sodium half-cell was subjected to constant current charge-discharge testing using the Xinwei battery testing system. The cycle performance was as follows: Figure 9 As shown, the results indicate that at 10 A·g -1 At extremely high current densities, the first-cycle discharge specific capacity can reach 130 mAh·g. -1After 50,000 ultra-long cycles, the discharge specific capacity still remains at 110 mAh·g. -1 The capacity retention rate is as high as 85%, and the coulomb efficiency remains close to 100% throughout the entire cycle.

[0073] In addition, the charge-discharge curves are as follows Figure 10 As shown in the charge-discharge curves, the average discharge voltage of this material is approximately 3.4V (vs. Na / Na). + Even at such high rates, the charge-discharge curves remain flat and have a very high degree of overlap, demonstrating excellent dynamic characteristics and structural stability.

[0074] As can be seen from the above, TP-PZ polymer exhibits extremely excellent performance in sodium-ion batteries, especially at 10 A·g -1 It achieved an ultra-long cycle life of 50,000 cycles at high rates, with a capacity retention rate of 85% and an average discharge voltage of up to 3.4V.

[0075] (III) Electrochemical performance testing of the potassium-ion half-cell prepared in Example 5 (1) Cyclic voltammetry test Cyclic voltammetry (CV) tests were performed on the assembled potassium half-cell using an electrochemical workstation. The results are as follows: Figure 11 As shown in the figure, the scan rate is 0.1 mV·s. -1 The voltage window is (2.0-4.0) V (vs. K / K). + As can be observed from the CV curves, in the first scan, the oxidation peak is located at about 3.6 V and the reduction peak is located at about 3.4 V; in the second scan, the position and intensity of the redox peaks remain basically unchanged, indicating that the material also has good electrochemical reversibility for the insertion / extraction of potassium ions.

[0076] (2) Constant current charge and discharge test The potassium half-cell was subjected to constant current charge-discharge testing using the Xinwei battery testing system. The cycle performance was as follows: Figure 12 As shown, at 1A·g -1 At the current density, the first-cycle discharge specific capacity is 117 mAh·g. -1 After 350 cycles, the discharge specific capacity is 70 mAh·g. -1 The capacity retention rate is approximately 60%, and the coulombic efficiency remains above 98% during the cycle.

[0077] In addition, the charge-discharge curves are as follows Figure 13 As shown in the charge-discharge curves, the average discharge voltage of this material can reach 3.5V (vs. K / K). + This is one of the highest voltage systems reported so far among organic cathode materials for potassium-ion batteries.

[0078] As can be seen from the above, the TP-PZ polymer also exhibits a high operating voltage (3.5V) and good cycle stability in potassium-ion batteries, proving that the material of this invention is effective against different alkali metal ions (Li). + Na + and K + () has wide applicability.

[0079] (iv) Electrochemical performance testing of the sodium-ion full battery prepared in Example 6 The sodium-ion full cell prepared in Example 6 was subjected to constant current charge-discharge testing using the Newway battery testing system. Cycle performance was as follows: Figure 14 As shown, the results indicate that at 1 A·g -1 (i.e. 1000 mA·g -1 (Based on the mass calculation of the positive electrode active material) Under high current density, the first-cycle discharge specific capacity reaches approximately 155 mAh·g. -1 The initial coulombic efficiency was close to 100%; after 2200 cycles, the discharge specific capacity remained at approximately 120 mAh·g. -1 The capacity retention rate is as high as 77%, and the coulombic efficiency remains stable at close to 100% throughout the entire cycle; that is, the charging capacity and the discharging capacity are highly overlapping, indicating that the full cell has excellent electrochemical reversibility.

[0080] From the above, it can be seen that the TP-PZ / / hard carbon sodium-ion full cell (sodium-ion full cell) based on the TP-PZ cathode prepared in Example 2 can achieve high rate (1 A·g) performance. -1 Under certain conditions, it exhibits excellent cycle stability and practicality; the full cell retains 77% capacity after 2200 cycles, with a coulombic efficiency approaching 100%, fully demonstrating the long-term stability, high reversibility, and reliability of the TP-PZ polymer cathode in practical battery systems. Furthermore, this full cell maintains a capacity of up to 120 mAh / g even at high current densities. -1 The TP-PZ polymer prepared in Example 1 exhibits stable capacity, demonstrating excellent rate performance and kinetic characteristics. This result shows that the TP-PZ polymer not only performs excellently in half-cell tests, but more importantly, it maintains stable electrochemical performance in a full-cell system matched with a practical anode material, laying a solid foundation for its practical application. The high capacity, high stability, and high rate performance exhibited by this full-cell system make it a promising candidate for applications in large-scale energy storage, portable power supplies, and automotive batteries.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cross-linked conjugated polymer, the structural formula of which is shown below: ,in, n is an integer from 20 to 93.

2. The method for preparing the crosslinked conjugated polymer according to claim 1, characterized in that, The preparation method includes: coupling polymerization of N1,N1,N4,N4-tetra(4-bromophenyl)benzene-1,4-diamine and 5,10-dihydrophenazine to obtain a crosslinked conjugated polymer.

3. The preparation method according to claim 2, characterized in that, The coupling polymerization reaction is the Buchwald-Hartwig arylation reaction.

4. The preparation method according to claim 3, characterized in that, The Buchwald-Hartwig aromatic amination reaction satisfies one or more of the following conditions: (i) The catalytic system for the Buchwald-Hartwig aromatic amination reaction is palladium catalysis; (ii) Based on (i), the palladium catalytic system includes a palladium source and a phosphine ligand; (iii) Based on (i), the reaction is carried out under strongly alkaline conditions; (iv) Based on (i), the reaction temperature is 80°C to 130°C.

5. The preparation method according to claim 4, characterized in that, (ii) The palladium source is selected from one or more combinations of tris(dibenzylacetone)palladium (0), [2-dicyclohexylphosphine-2',6'-diisopropoxybiphenyl]palladium chloride (II), or tetratriphenylphosphine palladium; (ii) The phosphine ligand is selected from one or more combinations of 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphine-2',6'-diisopropoxybiphenyl or 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl; (iii) The strong base is selected from one or more combinations of sodium tert-butoxide, sodium methoxide or triethylamine.

6. An alkali metal battery cathode material, characterized in that, Includes the crosslinked conjugated polymer as described in claim 1.

7. The alkali metal battery cathode material according to claim 6, characterized in that, The cathode material for alkali metal batteries includes cross-linked conjugated polymer, conductive carbon, and polyvinylidene fluoride in a mass ratio of (5.5–6.5):(2.5–3.5):

1.

8. An alkali metal battery positive electrode sheet, characterized in that, It is prepared from the alkali metal battery cathode material as described in claim 6 or 7.

9. An alkali metal battery, characterized in that, Including the alkali metal battery positive electrode sheet as described in claim 8.

10. The alkali metal battery according to claim 9, characterized in that, Alkali metal batteries are either alkali metal half-cells or alkali metal full-cells.

11. The alkali metal battery according to claim 9 or 10, characterized in that, Alkali metal batteries are lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries.

12. The application of the cross-linked conjugated polymer of claim 1 as a positive electrode active material for alkali metal batteries.

13. The application according to claim 12, characterized in that, Alkali metal batteries are lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries.

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