Hard carbon porous materials of tertiary amine-modified triazine polymers, their preparation methods and negative electrodes

Abstract

This application provides a hard carbon porous material of tertiary amine-modified triazine polymer, its preparation method, and an anode. Using tris(4-aminophenyl)amine and 3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and CuI as catalyst, CN-SL is synthesized via a Ullmann reaction. CTF-CN-1, containing a tertiary amine structure, is synthesized in a tube furnace at 450°C. CN-1000 is obtained by high-temperature calcination. The triazine porous framework of this application exhibits excellent physicochemical stability, high nitrogen content, and high porosity. After calcination, the interplanar spacing increases by 0.0086 nm, facilitating sodium ion insertion and extraction. As an anode for sodium-ion batteries, it achieves a specific capacity of 165.1 mAh / g after 10 cycles at a high current density of 2 A / g; a reversible capacity of 97.3 mAh / g after 300 cycles at a high current density of 1 A / g; and an impedance of 1.09 Ω. It has wide applications in secondary battery anode materials.

Description

Technical Field

[0001] This application belongs to the field of sodium battery technology, and particularly relates to a hard carbon porous material of tertiary amine-modified triazine polymer, its preparation method and negative electrode. Background Technology

[0002] With the development of human society, the discussion surrounding new energy sources continues to rise. Fossil energy is becoming increasingly depleted, and its use is accompanied by a certain degree of environmental pollution. Currently, new energy products encompass various forms, such as lithium batteries, fuel cells, and solar cells. Sodium-ion batteries (SIBs) have attracted much attention due to the widespread availability of low-cost sodium resources and their similar working mechanism to lithium-ion batteries (LIBs). Sodium is abundant in the Earth's crust, inexpensive, and possesses excellent low-temperature performance, environmental friendliness and compatibility, higher stability and safety, and even charging efficiency. However, due to the abundance of sodium... + The relatively large ionic radius and low redox potential of sodium-containing batteries (SIBs) result in relatively low energy density, which is an obstacle to their widespread industrialization. Therefore, it is of great significance to study an anode that facilitates sodium ion extraction and insertion to improve the electrochemical performance of batteries. Summary of the Invention

[0003] This application is made in view of the above-mentioned issues, and its purpose is to provide a hard carbon porous material of a tertiary amine functionalized triazine porous framework polymer with high nitrogen content, excellent porosity and physicochemical stability, which is conducive to sodium ion insertion and extraction and has high rate performance of sodium ion battery anode.

[0004] The first aspect of this application provides a hard carbon porous material of a tertiary amine-modified triazine polymer, wherein the mesoporous and macroporous specific surface areas of the hard carbon porous material are 2.8-2.9 m². 2 / g, microporous specific surface area is 1.4-1.6 m² 2 / g、(002) Peak position 2θ is 22°–25°、Interlayer spacing d 002 Its wavelength is 0.37–0.40 nm, and its structural formula is as follows: .

[0005] The second aspect of this application provides a method for preparing a hard carbon porous material of a tertiary amine-modified triazine polymer, which is obtained by the following steps: 1) Using tris(4-aminophenyl)amine and 3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and cuprous iodide as catalyst, the imino intermediate polyCN-SL was synthesized via the Ullmann reaction; the reaction formula is as follows: ; 2) The covalent triazine framework material CTF-CN-1 containing an imine structure was synthesized from CN-SL via a tube furnace; the reaction formula is as follows: ; 3) Heat CTF-CN-1 to 900-1200℃ in an argon atmosphere at a heating rate of 8-12℃ / min and react for 1.5-3h to obtain CN-1000.

[0006] In any embodiment, in step 1), the imino intermediate polyCN-SL is synthesized by reacting tris(4-aminophenyl)amine and 3,5-dibromobenzonitrile in a molar ratio of 1.0:2.8–3.0, using acetonitrile as solvent and cuprous iodide as catalyst, via the Ullman reaction at 80–85°C for 36–48 hours.

[0007] Slightly reducing the proportion of tris(4-aminophenyl)amine can retain the terminal group –NH2, avoid excessive cross-linking, and improve solubility; total monomer concentration: 0.08–0.12 M (based on acetonitrile), dilute solutions inhibit gelation.

[0008] In any embodiment, N,N'-dimethylethylenediamine and anhydrous potassium carbonate are added in step 1).

[0009] Anhydrous potassium carbonate (K₂CO₃) is used to neutralize HBr, maintain an alkaline environment to prevent cyano hydrolysis, and provide mild alkalinity to prevent the cyano group (–CN) in ADBBN from hydrolyzing into carboxylic acid under strong alkalinity / high temperature. N,N'-dimethylethylenediamine ligands enhance the catalytic efficiency of the catalyst.

[0010] In any embodiment, a moderately polar aprotic solvent is introduced into the solvent, and the volume ratio of the aprotic solvent to the strongly polar acetonitrile solvent is controlled at 1:1-4. The aprotic solvent is toluene or dioxane.

[0011] In acetonitrile systems, a single solvent often struggles to balance monomer solubility with the solvation of the growing chains. Introducing a moderately polar aprotic solvent (toluene or dioxane) into a mixed system with a highly polar solvent (acetonitrile) allows for gradient polarity control. As the reaction proceeds, the branched structure of polyCN-SL expands, and the hydrophobicity of the molecular chains increases. However, the high polarity of acetonitrile alone may lead to premature coiling and precipitation of the growing chains.

[0012] Controlling the ratio of mixed solvents to 1:1 to 1:2 (high polarity ratio) is beneficial in the early stages of the reaction when the monomer solubility is low or a faster catalytic rate is required. A higher acetonitrile ratio can enhance the solubility of cuprous iodide (CuI) and its ligands, thereby increasing the concentration of the catalytic center.

[0013] A 1:3 to 1:4 ratio (medium polarity) is favorable for high molecular weight polymers or specific porous structures; toluene or dioxane has good lipophilicity, which can better wet and swell the growing aromatic polymer chains. At this ratio, the polymer chains are in a "metastable swelling" state, and the reaction sites (amino and bromine) are always exposed at the solvent interface, which is conducive to the continued diffusion of monomers into the interior, thereby overcoming the "cage effect" caused by precipitation.

[0014] 0–15h (Initiation Phase): Acetonitrile accounts for 70% to ensure rapid activation of CuI / potential ligands (such as implicit L-proline), and moderate polarity promotes oxidative addition; 15–35h (Growth Phase): NMP is automatically added to an equal proportion to enhance solvation ability, allowing cyano / amino polymer chains to extend and delaying the gel point; Later Phase: The ionic liquid microdomains enrich copper catalytic active species, stabilizing anionic intermediates and accelerating reduction elimination. Simultaneously, its hydrophobicity shields trace amounts of water vapor, protecting cyano groups from hydrolysis. By using the ionic liquid as a "nanoreactor" rather than the main solvent, the drawbacks of high viscosity are avoided, enabling precise customization of the catalytic microenvironment.

[0015] The dioxane / acetonitrile system exhibits a relatively uniform polarity distribution. The oxygen atoms in the dioxane molecule possess weak coordination ability, which can help stabilize copper catalysts, and it is generally easier to obtain high molecular weight polymers than toluene.

[0016] Toluene / acetonitrile system: Significant polarity difference. It readily forms microemulsions or micellar environments, making it suitable for synthesizing polymer microspheres with unique spherical morphologies.

[0017] Preferred ratio is acetonitrile:dioxane = 1:3 (v / v).

[0018] By controlling the ratio, mixed solvents can produce a "solventization synergistic effect." By fine-tuning the polarity, the growing chain is kept in a "quasi-swollen state" rather than completely dissolved or completely precipitated. This ensures that the terminal amino and bromine atoms are always exposed to the catalytic environment at 80-85°C, thereby obtaining higher molecular weights or more regular pore structures.

[0019] Furthermore, during long-term reactions of 36-48 hours, the viscosity of the system increases exponentially with the formation of branched structures. High viscosity leads to impeded diffusion, causing local imbalances in the monomer molar ratio and generating defective structures (such as unreacted bromine terminal groups). This can be addressed by controlling the initial stage (high shear, 1-15h): using 500-800 rpm to ensure sufficient dispersion of the CuI catalyst in acetonitrile, forming a uniform catalytic microenvironment. In the middle stage (low shear, 16-30h): reducing to 200-300 rpm. Branched chains begin to form, and excessive shear force may damage the nascent microcrystalline structure or cause polymer mechanical degradation. In the later stage (pulse stirring): high-speed circulation for 5 minutes every hour. This breaks the already formed "solvent cage," forcibly removing byproducts encased within the polymer. Shear force or thermal convection is used to maintain the collision frequency of the reactants. This effectively solves the problems of increased local mass transfer resistance and active site entrapment in long-term Ullmann reactions.

[0020] In any embodiment, in step 2), CN-SL is heated to 400-480℃ in a tube furnace at a rate of 1-1.8℃ / min for 36-42h to undergo ionothermal polymerization, thereby synthesizing a covalent triazine framework material CTF-CN-1 containing an imine structure.

[0021] In any embodiment, in step 2), CN-SL is placed in a magnetic boat and mixed with zinc chloride in a certain proportion, and then crushed and mixed evenly; after nitrogen gas is introduced into the tube furnace, the magnetic boat containing CN-SL is placed in the tube furnace and heated to 450°C at a rate of 1°C / min under a nitrogen atmosphere, and the polymerization reaction is carried out for 40 hours to synthesize a porous organic polymer CTF-CN-1 containing imine and triazine ring structures.

[0022] In any embodiment, the pretreatment of CN-SL in step 2) is as follows: the purified CN-SL powder is vacuum dried at 80°C for 24 hours, and CN-SL and anhydrous ZnCl2 are mixed and ground evenly at a mass ratio of 1:6.

[0023] In any embodiment, CTF-CN-1 is heated to 1000°C at a heating rate of 10°C / min under an argon atmosphere and reacted for 2 h to obtain CN-1000.

[0024] In any embodiment, the interplanar spacing d of the CN-1000 is 0.35-0.40 nm.

[0025] In any embodiment, the mesoporous and macroporous specific surface area of ​​the CN-1000 is 2.8627 m². 2 / g, microporous specific surface area is 1.5269 m² 2 / g.

[0026] In any embodiment, the impedance of the CN-1000 is 0.88-1.109 Ω.

[0027] A third aspect of this application provides a negative electrode, which is a sodium-ion battery negative electrode, comprising the hard carbon porous material of this application or the hard carbon porous material obtained by the preparation method of this application.

[0028] The beneficial effects of this application: This application "binds" tertiary amine groups to triazine polymers to form tertiary amine triazine polymers, thereby realizing a hard carbon anode material for sodium-ion batteries with increased interlayer spacing. The covalent triazine polymers in this application are advantageous due to their high nitrogen content, excellent porosity, and physicochemical stability. This paper uses a high-temperature calcination method to prepare the hard carbon porous material CN-1000 from CTF-CN-1. After calcination, CN-1000 expands to 0.0086 nm compared to before calcination, and the increased interlayer spacing facilitates the insertion and extraction of sodium ions. After cycling at a high current density of 2 A / g, CN-1000, when returned to a low current density of 0.2 A / g, still retains a specific capacity of 165.1 mAh / g after 10 cycles; after 300 cycles at a high current density of 1 A / g, it still retains a reversible capacity of 97.3 mAh / g, and its impedance is 1.09 Ω. Therefore, CN-1000 is a potential anode material for sodium-ion batteries. Attached Figure Description

[0029] Figure 1 The XRD patterns of CTF-CN-1 and CN-1000 in Example 1 of this application are shown below. Figure 2 SEM images of CTF-CN-1 and CN-1000 from Embodiment 1 of this application; Figure 3 The FT-IR spectra of CN-1000 and CTF-CN-1 in Embodiment 1 of this application are shown below. Figure 4 This is a nitrogen adsorption curve of CN-1000 in Example 1 of this application at 77 K. Figure 5 This is a CV curve diagram of Embodiment 1 CN-1000 of this application; Figure 6 This is a rate performance diagram of Embodiment 1 CN-1000 of this application; Figure 7 This is a graph showing the cycling performance of Example 1 CN-1000 of this application at 0.2 A / g; Figure 8 This is a cycling performance diagram of Example 1 CN-1000 of this application at 1 A / g; Figure 9This is an EIS curve diagram of Embodiment 1 CN-1000 of this application. Detailed Implementation

[0030] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the tertiary amine-functionalized triazine porous framework polymer, hard carbon porous material, preparation method thereof, and battery negative electrode of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for a full understanding of this application by those skilled in the art and are not intended to limit the subject matter of the claims.

[0031] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0033] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0034] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0036] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0037] CTFs are a class of porous organic polymers with a triazine ring as their core structure. They are characterized by planar π-conjugated aromatic 1,3,5-triazine rings, and the desired structure can be obtained by controlling the synthesis conditions. CTFs are more cost-effective. The conjugation between the triazine and aromatic rings lowers the framework energy, thereby improving the polymer's chemical stability. The stable chemical structure makes them less prone to aging and deterioration, resulting in long service life and good economic benefits. The CTF framework contains a large number of CO2-loving nitrogen atoms, which also improves the CO2 adsorption and separation performance of samples. Furthermore, the covalent bonds connecting the CTF framework contribute to their superior chemical and thermal stability.

[0038] In one embodiment of this application, a hard carbon porous material based on a tertiary amine-modified triazine polymer is provided, wherein the mesopore and macropore specific surface area of ​​the hard carbon porous material is 2.8-2.9 m². 2 / g, microporous specific surface area is 1.4-1.6m² 2 / g、(002) Peak position 2θ is 22°–25°、Interlayer spacing d 002 Its wavelength is 0.37–0.40 nm, and its structural formula is as follows: .

[0039] Excessively high specific surface area can easily trigger side reactions and reduce initial efficiency; excessively low specific surface area limits wetting and ion transport. Na + The diameter is approximately 0.204 nm, d 002 Effective sodium intercalation requires a pore size >0.368 nm. The pore size must be <0.35 nm and greater than that of Na. + Diameter, orifice sieving effect, solvent molecules are sieved out, Na + After solvent removal, the ions enter the pores to form quasi-metallic clusters, generating a thin and stable NaF-based SEI, which significantly improves the first-efficiency and plateau capacity.

[0040] A method for preparing a hard carbon porous material of a tertiary amine-modified triazine polymer, comprising the following steps: 1) Using tris(4-aminophenyl)amine and 3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and cuprous iodide as catalyst, the imino intermediate polyCN-SL was synthesized by the Ullmann reaction at 85°C for 48 hours; the reaction formula is as follows: ; 2) CN-SL was heated to 450℃ in a tube furnace at a rate of 1℃ / min for 40 h to undergo ionothermal polymerization, synthesizing the covalent triazine framework material CTF-CN-1 containing a tertiary amine structure; the reaction formula is as follows: ; 3) Heat CTF-CN-1 to 900-1200℃ under an argon atmosphere at a heating rate of 8-12℃ / min for 1.5-3 hours to obtain CN-1000. In any embodiment, the interplanar spacing d of the CN-1000 hard carbon porous material is 0.3768 nm.

[0041] In any embodiment, the mesopore and macropore specific surface area of ​​the CN-1000 hard carbon porous material is 2.8627 m². 2 / g, with a microporous specific surface area of ​​1.5269 m². 2 / g.

[0042] In any embodiment, the impedance of the CN-1000 hard carbon porous material is 1.09 Ω.

[0043] In one embodiment of this application, a battery negative electrode is provided, which is a sodium-ion battery negative electrode, comprising the hard carbon porous material of the first aspect of this application or the hard carbon porous material prepared according to the method of the second aspect of this application.

[0044] In one embodiment of this application, a battery negative electrode is provided, which is a sodium-ion battery negative electrode and includes the hard carbon porous material of this application.

[0045] Example The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0046] Example 1 1) Using 0.2 mmol tris(4-aminophenyl)amine and 0.56 mmol 3,5-dibromobenzonitrile as raw materials, 15 mL acetonitrile as solvent, and 0.11 mmol cuprous iodide as catalyst, the imino intermediate polyCN-SL was synthesized by the Ullmann reaction at 85 °C for 48 hours. 2) CN-SL was heated to 450℃ in a tube furnace at a rate of 1℃ / min to undergo ionothermal polymerization to synthesize CTF-CN-1, a covalent triazine framework material containing a tertiary amine structure; 3) CTF-CN-1 was heated to 1000℃ in an argon atmosphere at a heating rate of 10℃ / min and reacted for 2 h to obtain CN-1000.

[0047] 4) Preparation of CN-1000 material as electrodes: The active material CN-1000, conductive agent Ketjen black (KP), and adhesive polyvinylidene fluoride (PVDF) were coated into a uniform slurry at a ratio of 8:1:1. This slurry was then coated onto a copper foil of uniform thickness and dried at 110°C under vacuum for at least 12 hours. The copper foil coated with the slurry was then rolled and cut into electrode sheets with a diameter of 12.5 mm.

[0048] Example 2 1) Using 0.2 mmol of tris(4-aminophenyl)amine and 0.6 mmol of 3,5-dibromobenzonitrile dissolved in 16 mL of anhydrous acetonitrile, and 0.12 mmol of cuprous iodide as a catalyst, the imino intermediate polyCN-SL was synthesized by the Ullmann reaction at 83 °C for 45 hours. 2) CN-SL was heated to 480℃ in a tube furnace at a rate of 1℃ / min for 36h to undergo ionothermal polymerization to synthesize CTF-CN-1, a covalent triazine framework material containing an imine structure; 3) CTF-CN-1 was heated to 1200℃ in an argon atmosphere at a heating rate of 8℃ / min and reacted for 1.5h to obtain CN-1000.

[0049] 4) Preparation of CN-1000 material as electrodes: The active material CN-1000, conductive agent Ketjen black (KP), and adhesive polyvinylidene fluoride (PVDF) were coated into a uniform slurry at a ratio of 8:1:1. This slurry was then coated onto a copper foil of uniform thickness and dried at 110°C under vacuum for at least 12 hours. The copper foil coated with the slurry was then rolled and cut into electrode sheets with a diameter of 12.5 mm.

[0050] Example 3 1) Using 0.2 mmol of tris(4-aminophenyl)amine and 0.58 mmol of 3,5-dibromobenzonitrile dissolved in 16 mL of anhydrous acetonitrile, and 0.12 mmol of cuprous iodide as a catalyst, the imino intermediate polyCN-SL was synthesized by the Ullmann reaction at 80 °C for 36 hours. 2) CN-SL was heated to 400℃ in a tube furnace at a rate of 1.8℃ / min for 42h to undergo ionothermal polymerization to synthesize CTF-CN-1, a covalent triazine framework material containing an imine structure; 3) CTF-CN-1 was heated to 900℃ in an argon atmosphere at a heating rate of 10℃ / min and reacted for 3h to obtain CN-1000.

[0051] 4) Preparation of CN-1000 material as electrodes: The active material CN-1000, conductive agent Ketjen black (KP), and adhesive polyvinylidene fluoride (PVDF) were coated into a uniform slurry at a ratio of 8:1:1. This slurry was then coated onto a copper foil of uniform thickness and dried at 110°C under vacuum for at least 12 hours. The copper foil coated with the slurry was then rolled and cut into electrode sheets with a diameter of 12.5 mm.

[0052] The CR2025 button cell was prepared in a glove box under an argon atmosphere. Sodium metal was used as the counter electrode, and the electrolyte was a 1 mol / L NaClO4EC:DEC = 1:1 10% fluoroethylene carbonate (FEC) solution. The separator was made of glass fiber. Electrochemical tests were performed on the fabricated CR2025 button cell.

[0053] The phase characterization of the materials in this application was performed using a Bruker-D8-Advance X-ray diffractometer (XRD, Cu Kα, λ=0.15418 nm), the surface morphology of the materials was characterized using a field emission scanning electron microscope (FE-SEM, SU8010), the chemical structure was determined using a Nicolet IS10 Fourier transform infrared spectrometer (FT-IR), and the specific surface area and pore size distribution of the triazine materials were determined using a 3Flex 5.02 surface area and pore size analyzer (BET).

[0054] This application uses the Blue Battery testing system for constant current charge-discharge testing, with a test voltage range of 0.01 V-3.00 V (vs. Na / Na+). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are performed using a CHI760E electrochemical workstation, with a CV test scan rate of 0.1 mV / s. -1 The EIS test frequency is 100 kHz - 0.1 Hz.

[0055] The phase structures of CTF-CN-1 and CN-1000 samples before and after calcination were determined, and XRD tests were performed on both materials. Figure 1 As shown, CN-1000 exhibits two peaks at 24° and 43°, indicating that the synthesized material has an amorphous structure, a characteristic of typical hard carbon materials. Test results show that the 2θ values ​​of the precursors CTF-CN-1 and CN-1000 are 24.76° and 24.16°, respectively. According to Bragg's formula, the interplanar spacing of the (002) crystal planes in the two materials is 0.3682 nm and 0.3768 nm, respectively. The results indicate that the interplanar spacing of CN-1000 after calcination is larger than that of the precursor CTF-CN-1, which is more favorable for Na… + The insertion and extraction of carbon. The impurity peak at 52° in the figure may be due to partial carbon graphitization.

[0056] The morphology of the material was further characterized by SEM, and the results are as follows: Figure 2 As shown in (af). From Figure 3-2(ac), it can be seen that CTF-CN-1 mainly exhibits a blocky distribution, and smaller pieces can also be observed, which may be fragments of the material. After this material undergoes high-temperature calcination, from... Figure 2 (df) It can be seen that the material becomes more loose and rough. This surface feature is beneficial to increasing the contact area between the material and the electrolyte, and at the same time, it can provide more electrochemical active sites for chemical reactions, thus improving electrochemical performance.

[0057] Figure 3 The infrared spectra of CN-1000 and CTF-CN-1 are shown in the figure. As indicated, a value of 1383 cm⁻¹ appears in the spectra of both compounds. -1 1646 cm -1 2346 cm -1 and 3437 cm -1 The characteristic absorption peak is at 1383 cm⁻¹. -1 and 1646 cm -1 The characteristic absorption can be attributed to the characteristic peak of the triazine group, at 2346 cm⁻¹. -1 A characteristic CO2 absorption peak appeared at 3437 cm⁻¹.-1 The presence of characteristic absorption peaks for tertiary amines indicates that the chemical structure of this organic porous polymer did not undergo significant changes before and after calcination at 1000℃, thus providing abundant functional groups for the application of sodium ion anode materials.

[0058] like Figure 4 The figure shows the nitrogen adsorption curve of CN-1000 at 77 K. It can be seen from the figure that the nitrogen adsorption capacity is low under low pressure conditions, but increases under high pressure conditions. P / P Nitrogen adsorption begins at a value of 0.85, and this adsorption curve is Type-III. There is a relatively small interaction force between nitrogen and the adsorbent. The adsorbent exhibits mesoporous properties, with a combined mesoporous and macroporous surface area of ​​2.8627 m². 2 / g, with a microporous specific surface area of ​​1.5269 m². 2 / g.

[0059] The materials were assembled into a 2025-type button cell and subjected to various electrochemical tests. This paper reveals the electrochemical reaction process of CN-1000 using cyclic voltammetry (CV), and the test results are as follows: Figure 5 As shown, the peak at 0.34 V during the initial charge-discharge process is due to the formation of a solid electrolyte film. The subsequent pair of redox peaks at 0.01 and 0.11 V are related to the insertion and extraction of sodium ions into and out of the graphite crystallites. The second and third cycles remain largely consistent, indicating that the hard carbon anode material we prepared possesses good electrochemical reversibility.

[0060] And we conducted rate performance tests on samples of CN-1000, such as... Figure 6 As shown in the figure, the CN-1000 sample exhibits excellent rate performance. At current densities of 0.2, 0.5, 1, and 2 A / g, the discharge specific capacity is 183.4, 158.8, 142.8, and 115.5 mAh / g, respectively. After cycling at a high current density of 2 A / g, when returning to a low current density of 0.2 A / g, the specific capacity after 10 cycles is still 165.1 mAh / g, demonstrating its excellent rate performance and cycle stability.

[0061] Figure 7 This is the cycling performance graph of CN-1000 at a low current density of 0.2 A / g. After 50 cycles at a current density of 0.2 A / g, CN-1000 still retains a battery capacity of 146.9 mAh / g. To verify the structural stability of the material, we also conducted cycling performance tests at a high current density of 1 A / g. Figure 8As shown, CN-1000 still retains a reversible capacity of 97.3 mAh / g after 300 cycles at a high current density of 1 A / g, which confirms that the hard carbon anode material we prepared has good electrochemical performance.

[0062] according to Figure 9 The electrochemical impedance spectroscopy (EIS) test shown is used to study the electronic dynamics of materials, such as... Figure 9 As shown, the analysis results based on the equivalent circuit indicate that the impedance of CN-1000 is 1.09Ω. The EIS results demonstrate that CN-1000 is a hard carbon anode material with low impedance. This anode material exhibits fast electron dynamics and charge transfer processes, and can provide better rate performance for sodium storage.

[0063] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A hard carbon porous material of a tertiary aminylated triazine polymer, characterized by, The specific surface area of the hard carbon porous material is 2.8-2.9 m 2 / g, the micropore specific surface area is 1.4-1.6 m 2 / g, the (002) peak position 2θ is 22°-25°, the interlayer spacing d 002 is 0.37-0.40 nm, and the structural formula is as follows: 。 2. A method for producing a hard carbon porous material of a tertiary amine-based triazine polymer, characterized by, Includes the following steps: 1) Using tris(4-aminophenyl)amine and 3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and cuprous iodide as catalyst, the imino intermediate polyCN-SL was synthesized via the Ullmann reaction; the reaction formula is as follows: ； 2) The covalent triazine framework material CTF-CN-1 containing an imine structure was synthesized from CN-SL via a tube furnace; the reaction formula is as follows: ； 3) CTF-CN-1 was heated to 900-1200℃ in an argon atmosphere at a heating rate of 8-12℃ / min and reacted for 1.5-3h to obtain hard carbon porous material CN-1000.

3. The preparation method according to claim 2, characterized in that, In step 1), the imino intermediate polyCN-SL is synthesized by reacting tris(4-aminophenyl)amine and 3,5-dibromobenzonitrile in a molar ratio of 1.0:2.8–3.0, using acetonitrile as solvent and cuprous iodide as catalyst, via the Ullman reaction at 80–85 °C for 36–48 hours.

4. The preparation method according to claim 2, characterized in that, In step 2), CN-SL is heated to 400-480℃ in a tube furnace at a rate of 0.6-1.8℃ / min for 36-42h to undergo ionothermal polymerization, thereby synthesizing CTF-CN-1, a covalent triazine framework material containing an imine structure.

5. The preparation method according to claim 2, characterized in that, In step 2), CN-SL is placed in a magnetic boat and mixed with zinc chloride in a certain proportion, and then crushed and mixed evenly. After nitrogen gas is introduced into the tube furnace, the magnetic boat containing CN-SL is placed in the tube furnace and heated to 450°C at a rate of 1°C / min under nitrogen atmosphere. The polymerization reaction is carried out for 40 hours to synthesize a porous organic polymer CTF-CN-1 containing imine and triazine ring structures.

6. The preparation method according to claim 2, characterized in that, In step 2), the pretreatment of CN-SL is as follows: the purified CN-SL powder is vacuum dried at 80℃ for 24h, and CN-SL and anhydrous ZnCl2 are mixed and ground evenly at a mass ratio of 1:

6.

7. The preparation method according to any one of claims 2-6, characterized in that, The mesopore and macropore specific surface area of the CN-1000 is 2.8627 m 2 / g, micropore specific surface area is 1.5269 m 2 / g.

8. The preparation method according to any one of claims 2-6, characterized in that, The impedance of the CN-1000 is 0.88-1.109 Ω.

9. A negative electrode, said negative electrode being a sodium-ion battery negative electrode, characterized in that, Includes the hard carbon porous material according to claim 1 or the hard carbon porous material obtained by the preparation method according to any one of claims 2 to 8.

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