A cross-linked conjugated polymer, its preparation method, and its application in alkali metal batteries.

Abstract

This invention belongs to the field of battery cathode material preparation technology, specifically relating to a cross-linked conjugated polymer, its preparation method, and its application in alkali metal batteries. When used as a cathode, this cross-linked conjugated polymer exhibits excellent performance in lithium, sodium, and potassium-ion batteries: an average discharge voltage as high as 3.4V–3.5V, which is beneficial for improving battery energy density; and it can still release more than 120 mAh·g at extremely high current densities. ‑1 Its high capacity exhibits extremely fast dynamic characteristics; even under harsh testing conditions, the capacity retention rate remains as high as 85% to 90%.

Description

Technical Field

[0001] This invention belongs to the field of battery cathode material preparation technology, specifically relating to a cross-linked conjugated polymer, its preparation method, and its application in alkali metal batteries. Background Technology

[0002] With the rapid growth in global demand for sustainable energy and large-scale energy storage technologies, the development of high-performance rechargeable battery systems has become a core challenge in the energy sector. Currently, commercially available lithium-ion batteries generally use inorganic transition metal oxides (such as lithium cobalt oxide, lithium iron phosphate, and ternary materials) as cathode materials, achieving some breakthroughs in energy density and cycle stability. However, these inorganic materials face two major bottlenecks: first, the uneven distribution of key elements such as cobalt and lithium resources leads to regional limitations and price fluctuation risks, hindering large-scale application; second, their rigid crystal structure has low tolerance for volume changes in ion insertion / extraction, particularly for larger alkali metal ions (such as Na+). + K + ) or multivalent ions (such as Zn) 2+ Mg 2+ Its poor compatibility makes it difficult to meet the development needs of the next generation of low-cost, diversified battery systems.

[0003] To overcome the inherent defects of inorganic materials, organic electrode materials have become a research hotspot for next-generation electrode materials due to their unique advantages. Compared to inorganic materials, organic electrode materials use abundant Earth-based elements such as C, H, O, and N as building blocks, possessing advantages such as abundant resources, high theoretical specific capacity, strong structural designability, environmental friendliness, and excellent mechanical flexibility, making them particularly suitable for low-cost, high-safety battery systems. Among them, p-type organic materials containing N-heterocyclic rings (such as triphenylamine derivatives and phenazine derivatives) can achieve high voltage ratings up to 3.5V (vs. Li / Li). + The operating voltage of the cathode material can effectively improve the energy density of the battery and is considered one of the most promising cathode materials for application.

[0004] Despite the high voltage potential exhibited by p-type organic materials, their practical applications still face an inherent structure-performance contradiction: small-molecule active substances (such as triphenylamine and phenazine monomers) and their redox products have high solubility in organic electrolytes, leading to severe loss of active substances and a sharp decline in battery cycle life. To address the solubility issue, researchers polymerized active monomers into linear polymers. While this reduced solubility, the tight packing and disordered entanglement of the linear chains hindered the electrolyte's wetting and access to the internal redox active sites, resulting in tortuous ion diffusion paths, low utilization of active sites, and actual specific capacities generally below 100 mAh·g. -1Furthermore, the rate performance of organic materials is poor. Therefore, it is necessary to develop an organic cathode material that can simultaneously solve the problems of solubility and low utilization of active sites, and synergistically achieve high operating voltage, high specific capacity, excellent rate performance, and ultra-long cycle stability. Summary of the Invention

[0005] The purpose of this invention is to provide a cross-linked conjugated polymer, its preparation method, and its application in alkali metal batteries. This invention aims to overcome the contradiction between the dissolution problem and low utilization rate of active sites that are common in organic cathode materials in the prior art, and to achieve a synergistic balance of high voltage, high capacity, high rate capability, and long cycle performance.

[0006] To achieve the above objectives, the present invention can adopt the following technical solutions:

[0007] In one aspect, this invention provides a crosslinked conjugated polymer, the structural formula of which is shown below:

[0008] , where n is an integer from 20 to 93.

[0009] Another aspect of the present invention provides a method for preparing the above-mentioned crosslinked conjugated polymer, the method comprising: performing a coupling polymerization reaction of N1,N1,N4,N4-tetra(4-bromophenyl)benzene-1,4-diamine and 5,10-dihydrophenazine to obtain the crosslinked conjugated polymer.

[0010] Preferably, in the above preparation method, the coupling polymerization reaction is a Buchwald-Hartwig arylation reaction.

[0011] More preferably, the above Buchwald-Hartwig arylation reaction satisfies any one or more of the following conditions:

[0012] (i) The catalytic system for the Buchwald-Hartwig aromatic amination reaction is palladium catalysis;

[0013] (ii) Based on (i), the palladium catalytic system includes a palladium source and a phosphine ligand;

[0014] (iii) Based on (i), the reaction is carried out under strongly alkaline conditions;

[0015] (iv) Based on (i), the reaction temperature is 80°C to 130°C.

[0016] More preferably, in the above preparation method,

[0017] (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;

[0018] (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;

[0019] (iii) The strong base is selected from one or more combinations of sodium tert-butoxide, sodium methoxide or triethylamine.

[0020] In another aspect, the present invention provides an alkali metal battery cathode material comprising the aforementioned cross-linked conjugated polymer.

[0021] Preferably, the above-mentioned alkali metal battery cathode material includes a cross-linked conjugated polymer, conductive carbon, and polyvinylidene fluoride in a mass ratio of (5.5-6.5):(2.5-3.5):1.

[0022] In another aspect, the present invention provides an alkali metal battery positive electrode sheet, which is prepared from the above-mentioned alkali metal battery positive electrode material.

[0023] In another aspect, the present invention provides an alkali metal battery comprising the above-described alkali metal battery positive electrode.

[0024] Preferably, the above-mentioned alkali metal battery is an alkali metal half-cell or an alkali metal full-cell.

[0025] Preferably, the alkali metal battery is a lithium-ion battery, a sodium-ion battery, or a potassium-ion battery.

[0026] In another aspect, the present invention provides the application of the above-mentioned cross-linked conjugated polymer as a positive electrode active material for alkali metal batteries.

[0027] Preferably, in the above applications, the alkali metal battery is a lithium-ion battery, a sodium-ion battery, or a potassium-ion battery.

[0028] The beneficial effects of this invention include at least the following:

[0029] (1) The cross-linked conjugated polymer provided by this invention overcomes the contradiction between the dissolution problem and the low utilization rate of active sites that are common in existing organic cathode materials. It achieves a synergistic unity of high voltage, high capacity, high rate and long cycle performance. Specifically, the battery constructed by this invention can withstand 50,000 charge-discharge cycles, indicating that it does not dissolve in the electrolyte and can reach 130 mAh·g -1 The discharge capacity indicates that its active sites are fully utilized;

[0030] (2) When the cross-linked conjugated polymer provided by the present invention is used as a positive electrode, it exhibits excellent performance in lithium, sodium, and potassium-ion batteries: high operating voltage: the average discharge voltage is as high as 3.4V to 3.5V, which is beneficial to improving the energy density of the battery; high specific capacity and high rate performance: even at extremely high current densities (e.g., up to 10A·g in sodium batteries) -1 Even at approximately 50°C, it can still release over 120 mAh·g. -1 Its high capacity exhibits extremely fast kinetic characteristics; ultra-long cycle life: under harsh testing conditions (e.g., sodium batteries at 10 A·g) -1 After 50,000 cycles, the lithium battery is at 10 A·g -1 Even after 3000 cycles, the capacity retention remains as high as 85%–90%, which is superior to previously reported organic electrode materials. For example, the average discharge potential of the PTCDI-DAQ polymer is 1.7V at 100 mA·g. -1 The initial discharge capacity at the current density is 203 mAh·g -1 After 100 cycles, only 121 mAh·g remained. -1 The capacity retention rate is only 60%; the average discharge potential of PVDMP polymer is 3.2V, but after 4000 cycles at a current density of 5C, the capacity retention rate is only 68%.

[0031] (3) The preparation method of cross-linked conjugated polymer provided by the present invention is simple, efficient, universal, relatively mild, and has a high total yield, providing a feasible way for the large-scale preparation of cross-linked conjugated polymer. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the synthesis of the cross-linked conjugated polymer TP-PZ.

[0033] Figure 2 Infrared spectra of the cross-linked conjugated polymer TP-PZ and related raw materials;

[0034] Figure 3 This is the solid-state carbon NMR spectrum of the cross-linked conjugated polymer TP-PZ;

[0035] Figure 4 The image shows the gel permeation chromatogram of the cross-linked conjugated polymer TP-PZ.

[0036] Figure 5 The CV curve of the cross-linked conjugated polymer TP-PZ cathode in a lithium half-cell;

[0037] Figure 6 The graph shows the cycling performance of the cross-linked conjugated polymer TP-PZ cathode in a lithium half-cell.

[0038] Figure 7This is a charge-discharge curve of the cross-linked conjugated polymer TP-PZ cathode in a lithium half-cell.

[0039] Figure 8 The CV curve of the cross-linked conjugated polymer TP-PZ cathode in a sodium half-cell is shown.

[0040] Figure 9 The graph shows the cycling performance of the cross-linked conjugated polymer TP-PZ cathode in a sodium half-cell.

[0041] Figure 10 This is a charge-discharge curve of the cross-linked conjugated polymer TP-PZ cathode in a sodium half-cell.

[0042] Figure 11 The CV curve of the cross-linked conjugated polymer TP-PZ cathode in a potassium half-cell is shown.

[0043] Figure 12 The graph shows the cycling performance of the cross-linked conjugated polymer TP-PZ cathode in a potassium half-cell.

[0044] Figure 13 This is a charge-discharge curve of the cross-linked conjugated polymer TP-PZ cathode in a potassium half-cell.

[0045] Figure 14 Cyclic performance of a sodium full cell assembled with a cross-linked conjugated polymer TP-PZ cathode and a hard carbon anode. Detailed Implementation

[0046] The illustrated embodiments are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the illustrated embodiments. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description of the invention still fall within the protection scope of the present invention.

[0047] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0048] In a first aspect, embodiments of the present invention provide a crosslinked conjugated polymer, the structural formula of which is shown below:

[0049] , where n is an integer from 20 to 93.

[0050] It should be noted that the three-dimensional covalently cross-linked network structure designed in this invention 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 shuttle movement of active materials in the electrolyte, ensuring ultra-high cycling stability; on the other hand, the highly cross-linked and hyperbranched topology forms a porous framework at the microscopic level, providing three-dimensional channels for sufficient electrolyte wetting and rapid ion transport, enabling the efficient utilization of the high-density redox active sites (triphenylamine and phenazine units) within the network, thereby achieving high specific capacity.

[0051] It should also be noted that this cross-linked conjugated polymer combines the advantages of triphenylamine units (p-type, contributing to a high voltage plateau) and phenazine units (p-type, contributing to multi-electron transfer). When used as a positive electrode, this cross-linked conjugated polymer exhibits excellent performance in lithium, sodium, and potassium-ion batteries: high operating voltage: the average discharge voltage is as high as 3.4V–3.5V, which is beneficial for improving the battery's energy density; high specific capacity and high rate performance: even at extremely high current densities (e.g., up to 10 A·g in sodium batteries). -1 Even at 50°C, it can still release more than 120 mAh·g. -1 Its high capacity exhibits extremely fast kinetic characteristics; ultra-long cycle life: under harsh testing conditions (e.g., sodium batteries at 10 A·g) -1 After 50,000 cycles (compared to 3,000 cycles at 50C for lithium batteries), the capacity retention rate remains as high as 85%–90%. This demonstrates that the cross-linked conjugated polymer exhibits excellent performance in lithium, sodium, and potassium alkali metal ion batteries, showcasing its enormous potential as a "universal" high-performance organic cathode platform.

[0052] It should also be noted that the cross-linked conjugated polymer structural unit in this invention can be represented by the following general formula: [(TPA-core)]m[(PZ-linker)]n; where TPA-core represents a tetravalent cross-linking central unit derived from N1,N1,N4,N4-tetra(4-halophenyl)phenyl-1,4-diamine; PZ-linker represents a bivalent 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.

[0053] In a second aspect, embodiments of the present invention provide a method for preparing the above-mentioned crosslinked conjugated polymer, the method comprising: coupling polymerization of N1,N1,N4,N4-tetra(4-bromophenyl)benzene-1,4-diamine and 5,10-dihydrophenazine to obtain the crosslinked conjugated polymer.

[0054] It should be noted that the preparation method of cross-linked conjugated polymers provided by the present invention is simple, efficient, universal, relatively mild, and has a high overall yield, providing a feasible approach for the large-scale preparation of cross-linked conjugated polymers.

[0055] In some specific examples, the coupling polymerization reaction in the above preparation method is the Buchwald-Hartwig arylation reaction.

[0056] It should be noted that the coupling polymerization reaction refers to all reactions known in the art that can achieve coupling polymerization, and the present invention preferentially selects the Buchwald-Hartwig aromatic amination reaction. Furthermore, the Buchwald-Hartwig aromatic amination reaction is known in the art.

[0057] In some specific examples, the above Buchwald-Hartwig arylation reaction satisfies one or more of the following conditions:

[0058] (i) The catalytic system for the Buchwald-Hartwig aromatic amination reaction is a palladium catalytic system; specifically, the catalytic system for the Buchwald-Hartwig aromatic amination reaction in this invention can preferably be a palladium catalytic system, which is more suitable for the preparation of cross-linked conjugated polymers in this invention.

[0059] (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;

[0060] (iii) Based on (i), the reaction is carried out under strongly alkaline conditions;

[0061] (iv) Based on (i), the reaction temperature is 80°C to 130°C, such as 90°C, 100°C, 110°C or 120°C.

[0062] In some specific examples, in the above preparation method,

[0063] (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;

[0064] (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;

[0065] (iii) The strong base is selected from one or more combinations of sodium tert-butoxide, sodium methoxide or triethylamine.

[0066] Thirdly, embodiments of the present invention provide an alkali metal battery cathode material, which includes the above-mentioned cross-linked conjugated polymer.

[0067] It should be noted that the cross-linked conjugated polymer in this invention can be used as a positive electrode active material for alkali metal batteries, and other auxiliary materials can be added to prepare it into a positive electrode material for alkali metal batteries.

[0068] In some specific examples, the above-mentioned alkali metal battery cathode material includes a cross-linked conjugated polymer, conductive carbon, and polyvinylidene fluoride in a mass ratio of (5.5-6.5):(2.5-3.5):1.

[0069] It should be noted that other auxiliary materials may be conductive carbon and polyvinylidene fluoride, and the preferred mass ratio of cross-linked conjugated polymer, conductive carbon, and polyvinylidene fluoride is (5.5-6.5):(2.5-3.5):1. Furthermore, it should be understood that the alkali metal battery cathode material may also include a solvent, which is known in the art, such as NMP (methylpyrrolidone).

[0070] Fourthly, embodiments of the present invention provide an alkali metal battery positive electrode sheet, which is prepared from the above-mentioned alkali metal battery positive electrode material.

[0071] It should be noted that after the alkali metal battery positive electrode material in this invention is formed into a slurry, it can be coated onto a current collector (such as an aluminum foil current collector) and dried to obtain an alkali metal battery positive electrode sheet.

[0072] Fifthly, embodiments of the present invention provide an alkali metal battery, which includes the above-mentioned alkali metal battery positive electrode sheet.

[0073] It should be noted that the alkali metal battery positive electrode sheet in this invention can be assembled with an alkali metal battery negative electrode and an electrolyte to obtain an alkali metal battery. Furthermore, both the alkali metal battery negative electrode and the electrolyte are well known in the art.

[0074] In some specific examples, the alkali metal battery described above is an alkali metal half-cell or an alkali metal full-cell.

[0075] It should be noted that the alkali metal battery positive electrode sheet in this invention is suitable for alkali metal half-cells or alkali metal full-cells, and the specific choice can be made according to the actual situation.

[0076] In some specific examples, the aforementioned alkali metal batteries are lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries.

[0077] It should be noted that the alkali metal batteries in this invention include, but are not limited to, lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries.

[0078] Sixthly, embodiments of the present invention provide an application of the above-mentioned cross-linked conjugated polymer as a positive electrode active material for alkali metal batteries.

[0079] It should be noted that the cross-linked conjugated polymer in this invention can be used as an active material for the positive electrode of alkali metal batteries, and it exhibits excellent electrochemical performance when used as an active material for the positive electrode of alkali metal batteries.

[0080] In some specific examples, the alkali metal batteries described above are lithium-ion, sodium-ion, or potassium-ion batteries.

[0081] It should be noted that the alkali metal batteries in this invention include, but are not limited to, lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries.

[0082] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0083] Preparation Examples

[0084] Example 1

[0085] This invention provides a crosslinked conjugated polymer (TP-PZ) and its preparation method.

[0086] (1) Preparation of intermediate N1,N1,N4,N4-tetra(4-bromophenyl)phenyl-1,4-diamine (TP-2Br)

[0087] (1-1) In a 500 mL round-bottom flask, add N1,N1,N4,N4-tetraphenyl-1,4-phenylenediamine (1 mmol, 488.6 mg), then add 50 mL of dichloromethane (CH2Cl2) as a solvent and stir magnetically to dissolve it;

[0088] (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 time, with an interval of 15 minutes between each addition;

[0089] (1-3) After the addition of the materials, the reaction mixture shall be stirred continuously at room temperature for 8 hours to ensure that the bromination reaction is fully carried out;

[0090] (1-4) After the reaction is complete, the solvent dichloromethane is removed by rotary evaporation to obtain the crude product;

[0091] (1-5) The crude product was washed multiple times with deionized water, then filtered, and dried under vacuum at 60°C for 12 hours to finally obtain a pure product in the form of white powder, namely N1,N1,N4,N4-tetra(4-bromophenyl)benzene-1,4-diamine, with a yield of up to 95%.

[0092] (2) Preparation of cross-linked conjugated polymer (TP-PZ)

[0093] (2-1) Under strictly anhydrous and oxygen-free conditions (operated in an argon-filled glove box), the above-prepared N1,N1,N4,N4-tetra(4-bromophenyl)phenyl-1,4-diamine (0.6 mmol, 482.5 mg), 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-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (XPhos, 0.24 mmol, 113.2 mg) were sequentially added to a dry, pressure-resistant reaction tube; subsequently, 30 mL of ultra-dry toluene was added as a solvent;

[0094] (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;

[0095] (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;

[0096] (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;

[0097] (2-5) Dry the washed solid in a vacuum oven;

[0098] (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;

[0099] (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%.

[0100] Example 2

[0101] This invention provides a TP-PZ positive electrode sheet and its preparation method.

[0102] 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.

[0103] Example 3

[0104] This invention provides a lithium-ion half-cell based on the TP-PZ cathode prepared in Example 2 and its assembly process.

[0105] 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.

[0106] Example 4

[0107] This invention provides a sodium-ion half-cell based on the TP-PZ cathode prepared in Example 2 and its assembly process.

[0108] 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.

[0109] Example 5

[0110] This invention provides a potassium-ion half-cell based on the TP-PZ cathode prepared in Example 2 and its assembly process.

[0111] 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.

[0112] Example 6

[0113] 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.

[0114] (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.

[0115] (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.

[0116] Characterization test

[0117] 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. -1 The 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.

[0118] 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.

[0119] 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.

[0120] Performance testing

[0121] (I) Electrochemical performance test of the lithium-ion half-cell assembled in Example 3

[0122] (1) Cyclic voltammetry test

[0123] 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.

[0124] (2) Constant current charge and discharge test

[0125] 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.

[0126] 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.

[0127] 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.

[0128] (II) Electrochemical performance testing of the sodium-ion half-cell prepared in Example 4

[0129] (1) Cyclic voltammetry test

[0130] 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.

[0131] (2) Constant current charge and discharge test

[0132] 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. -1 After 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.

[0133] 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.

[0134] 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.

[0135] (III) Electrochemical performance testing of the potassium-ion half-cell prepared in Example 5

[0136] (1) Cyclic voltammetry test

[0137] 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.

[0138] (2) Constant current charge and discharge test

[0139] 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.

[0140] 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.

[0141] 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.

[0142] (iv) Electrochemical performance testing of the sodium-ion full battery prepared in Example 6

[0143] 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 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.

[0144] 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.

[0145] 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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