Amino- and tertiary amine-functionalized triazine hard carbon porous materials, methods of making, and negative electrodes

Abstract

This application provides an amino- and tertiary-amine-modified triazine hard carbon porous material, its preparation method, and an anode. Using tris(4-aminophenyl)amine and 4-amino-3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and CuI as catalyst, NH2-SL is synthesized via a Ullmann reaction. The mixture is then reacted in a tube furnace at 450℃ for 40 h to synthesize CTF-NH2 containing an imine structure. Subsequently, high-temperature calcination is performed to synthesize NH2-1000. The triazine porous framework obtained in this application exhibits excellent physicochemical stability, high nitrogen content, and high porosity. Compared to the material before calcination at 1000℃, the interplanar spacing of the hard carbon porous material increases by 0.0034 nm, which is more conducive to sodium ion insertion and extraction. Therefore, the prepared NH2-1000, as a sodium-ion battery anode, demonstrates a high reversible capacity of 209.1 mAh / g in a 2A / g rate performance test, making it widely applicable as a secondary battery anode material.

Description

Technical Field

[0001] This application belongs to the field of sodium battery technology, and particularly relates to an amino and tertiary amine-modified triazine hard carbon porous material, its preparation method, and a 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 amino and tertiary amine bifunctionalized triazine porous framework polymer with physicochemical stability, high nitrogen content and high porosity, which is conducive to sodium ion insertion and extraction and has high rate performance of sodium ion battery negative electrode.

[0004] The first aspect of this application provides an amino- and tertiary amine-modified triazine hard carbon porous material, wherein the mesoporous and macroporous specific surface area of ​​the hard carbon porous material is 2.15-2.45 m². 2 / g, microporous specific surface area is 1.02-1.3 m² 2 / g, (002) peak position 2θ is 22°–25°, interlayer spacing d002 is 0.37–0.40 nm, the structural formula is as follows: .

[0005] Hard carbon porous materials formed by the generation of amorphous cross-linked polymers.

[0006] The second aspect of this application provides a method for preparing amino- and tertiary-amine-modified triazine hard carbon porous materials, which are obtained by the following steps: 1) Using tris(4-aminophenyl)amine and 4-amino-3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and cuprous iodide as catalyst, the imino intermediate polyNH2-SL (poly-(4-amino-3,5-bis(4-(diphenylamino)phenyl)amino)benzonitrile) was synthesized via the Ullmann reaction; the reaction formula is as follows: ; 2) The covalent triazine framework material CTF-NH2 (poly-(4-amino-2,4,6-tris-(4-aminophenyl)-[1,3,5]triazine)) containing an imine structure was synthesized by NH2-SL in a tube furnace; the reaction formula is as follows: ; 3) Heat CTF-NH2 to 900-1200℃ in an argon atmosphere at a heating rate of 8-10℃ / min and react for 1.5-3h to obtain hard carbon porous material NH2-1000.

[0007] In any embodiment, in step 1), the imino intermediate poly(NH2-SL) is synthesized by reacting tris(4-aminophenyl)amine and 4-amino-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.

[0008] 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.

[0009] In any embodiment, N,N'-dimethylethylenediamine and anhydrous potassium carbonate are added in step 1).

[0010] 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.

[0011] 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.

[0012] 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 polyNH2-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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] Toluene / acetonitrile system: Significant polarity difference. It readily forms microemulsions or micellar environments, making it suitable for synthesizing polymer microspheres with unique spherical morphologies.

[0018] Preferred ratio is acetonitrile:dioxane = 1:3 (v / v).

[0019] 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.

[0020] 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.

[0021] In any embodiment, in step 2), NH2-SL is heated to 400-480℃ in a tube furnace at a rate of 1-1.8℃ / min for 36-42h to synthesize a covalent triazine framework material CTF-NH2 containing an imine structure.

[0022] In any embodiment, in step 2), NH2-SL is heated to 450°C in a tube furnace at a rate of 1°C / min for 40 hours to undergo ionothermal polymerization to synthesize a covalent triazine framework material CTF-NH2 containing an imine structure.

[0023] In any embodiment, the pretreatment of NH2-SL in step 2) is as follows: the purified NH2-SL powder is vacuum dried at 80°C for 24 hours or operated under an infrared environment to avoid water adsorption, and the NH2-SL and anhydrous ZnCl2 are mixed and ground evenly at a mass ratio of 1:6.

[0024] In any embodiment, CTF-NH2 is heated to 1000°C at a heating rate of 10°C / min under an argon atmosphere and reacted for 2 h to obtain NH2-1000.

[0025] In any embodiment, the interplanar spacing d of the NH2-1000 hard carbon porous material is 0.3786 nm.

[0026] In any embodiment, the mesoporous and macroporous specific surface area of ​​the NH2-1000 hard carbon porous material is 2.2533 m². 2 The specific surface area of ​​the micropores is 1.1458 m² / g. 2 / g.

[0027] In any embodiment, the impedance of the NH2-1000 hard carbon porous material is 1.07-1.25Ω.

[0028] The third aspect of this application provides a negative electrode, 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 obtained by the preparation method of the second aspect.

[0029] The beneficial effects of this application: The triazine porous framework polymer obtained in this application possesses excellent physicochemical stability, high nitrogen content, and high porosity, making it widely applicable in secondary battery anode materials. This paper uses a high-temperature calcination method to prepare a hard carbon porous material (NH2-1000) from CTF-NH2. Compared to the material before calcination at 1000℃, the interplanar spacing of the prepared hard carbon porous material increased by 0.0034 nm, which is more conducive to sodium ion insertion and extraction. Therefore, the prepared NH2-1000, as a sodium-ion battery anode, exhibited a high reversible capacity of 209.1 mAh / g in a 2A / g rate performance test. Attached Figure Description

[0030] Figure 1 The XRD patterns of CTF-NH2 and NH2-1000 in Example 1 of this application are shown below. Figure 2 Here are SEM images of CTF-NH2 and NH2-1000 from Example 1 of this application; Figure 3 The FT-IR spectra of NH2-1000 and CTF-NH2 in Example 1 of this application are shown below. Figure 4 This is a nitrogen adsorption curve of NH2-1000 under 77 K in Example 1 of this application; Figure 5 This is a CV curve diagram of Example 1NH2-1000 of this application; Figure 6 This is a rate performance diagram of NH2-1000 in Example 1 of this application; Figure 7 The graph shows the cycling performance of Example 1NH2-1000 of this application at 0.2 A / g and 1 A / g. Figure 8 This is the EIS curve of NH2-1000 in Example 1 of this application. Detailed Implementation

[0031] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the amino and tertiary amine bifunctionalized triazine porous framework polymer, hard carbon porous material, 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0032] 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.

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

[0034] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0035] 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.

[0036] 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.

[0037] 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).

[0038] 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.

[0039] In one embodiment of this application, an amino- and tertiary-amine-modified triazine hard carbon porous material is provided, wherein the mesoporous and macroporous specific surface area of ​​the hard carbon porous material is 2.15-2.45 m². 2 / g, microporous specific surface area is 1.02-1.3 m² 2 / g, (002) peak position 2θ is 22°–25°, interlayer spacing d002 is 0.37–0.40 nm, the structural formula is as follows: .

[0040] A method for preparing amino- and tertiary-amine-modified triazine hard carbon porous materials, comprising the following steps: 1) Using tris(4-aminophenyl)amine and 4-amino-3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and cuprous iodide as catalyst, the imino intermediate polyNH2-SL (poly-(4-amino-3,5-bis(4-(diphenylamino)phenyl)amino)benzonitrile) was synthesized via the Ullmann reaction at 85°C for 48 hours; the reaction formula is as follows: ; 2) NH2-SL was heated to 450℃ in a tube furnace at a rate of 1℃ / min for 40 h for ionothermal polymerization to synthesize CTF-NH2 (poly-(4-amino-2,4,6-tris-(4-aminophenyl)-[1,3,5]triazine)), a covalent triazine framework material containing an imine structure; the reaction formula is as follows: ; 3) CTF-NH2 was heated to 1000℃ in an argon atmosphere at a heating rate of 10℃ / min and reacted for 2 h to obtain the hard carbon porous material NH2-1000.

[0041] In any embodiment, the interplanar spacing d of the NH2-1000 hard carbon porous material is 0.3786 nm.

[0042] In any embodiment, the mesoporous and macroporous specific surface area of ​​the NH2-1000 hard carbon porous material is 2.2533 m². 2 The specific surface area of ​​the micropores is 1.1458 m² / g. 2 / g.

[0043] In any embodiment, the impedance of the NH2-1000 hard carbon porous material is 1.17 Ω.

[0044] 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.

[0045] Example 1 1) Using 0.2 mmol (87.2 mg) of tris(4-aminophenyl)amine and 0.56 mmol (185.5 mg) of 4-amino-3,5-dibromobenzonitrile dissolved in 15 mL of anhydrous acetonitrile, and with 0.11 mmol of cuprous iodide as a catalyst, the imino intermediate poly(NH2-SL) was synthesized by the Ullmann reaction at 85 °C for 48 hours. 2) NH2-SL was heated to 450℃ in a tube furnace at a rate of 1℃ / min for 40h to undergo ionothermal polymerization to synthesize CTF-NH2, a covalent triazine framework material containing an imine structure; 3) CTF-NH2 was heated to 1000℃ in an argon atmosphere at a heating rate of 10℃ / min and reacted for 2 h to obtain NH2-1000.

[0046] 4) Preparation of NH2-1000 material as electrodes: The active material NH2-1000, 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.

[0047] Example 2 1) Using 0.2 mmol of tris(4-aminophenyl)amine and 0.6 mmol of 4-amino-3,5-dibromobenzonitrile dissolved in 16 mL of anhydrous acetonitrile, and 0.12 mmol of cuprous iodide as a catalyst, the imino intermediate poly(NH2-SL) was synthesized by the Ullmann reaction at 83 °C for 45 hours. 2) NH2-SL was heated to 480℃ in a tube furnace at a rate of 1℃ / min for 36h to undergo ionothermal polymerization to synthesize CTF-NH2, a covalent triazine framework material containing an imine structure; 3) CTF-NH2 was heated to 1200℃ in an argon atmosphere at a heating rate of 8℃ / min and reacted for 1.5h to obtain NH2-1000.

[0048] 4) Preparation of NH2-1000 material as electrodes: The active material NH2-1000, 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.

[0049] Example 3 1) Using 0.2 mmol of tris(4-aminophenyl)amine and 0.58 mmol of 4-amino-3,5-dibromobenzonitrile dissolved in 16 mL of anhydrous acetonitrile, and 0.12 mmol of cuprous iodide as a catalyst, the imino intermediate poly(NH2-SL) was synthesized by the Ullmann reaction at 80 °C for 36 hours. 2) NH2-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-NH2, a covalent triazine framework material containing an imine structure; 3) CTF-NH2 was heated to 900℃ in an argon atmosphere at a heating rate of 10℃ / min and reacted for 3h to obtain NH2-1000.

[0050] 4) Preparation of NH2-1000 material as electrodes: The active material NH2-1000, 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.

[0051] The materials were prepared into electrodes, and then CR2025 button cells were fabricated for electrochemical testing. First, the active material NH2-1000 and the conductive agent Ketjen black (KP), along with the 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 under vacuum at 110°C 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) were performed using a CHI760E electrochemical workstation. The CV scan rate was 0.1 mV / s. -1 The EIS test frequency is 100 kHz - 0.1 Hz.

[0055] Figure 1 The XRD patterns of CTF-NH2 and NH2-1000 are shown. First, the crystal structure of CTF-NH2 and NH2-1000 materials was analyzed by XRD, such as... Figure 1 As shown, NH2-1000 exhibits two bun-shaped diffraction peaks at 24° and 43°. The appearance of these peaks indicates that the material synthesized in this paper has an amorphous structure, a characteristic of typical hard carbon materials. Test results show that the 2θ values ​​of the precursors CTF-NH2 and NH2-1000 are 24.25° and 24.03°, respectively. According to Bragg's law (2... d sin θ = n λ Substitute θ Calculations show that the interplanar spacing d at (002) for the two materials is 0.3752 nm and 0.3786 nm, respectively. λ =0.15418 nm) The results show that the interplanar spacing of NH2-1000 after calcination is larger than that of the precursor CTF-NH2, which is more favorable for Na + The insertion and extraction of carbon. The impurity peak at 52° in the figure is due to partial carbon graphitization.

[0056] Figure 2 (ad) shows the SEM images of CTF-NH2 and NH2-1000. Further characterization of the material's microstructure using SEM is shown in the following figures. Figure 2 As shown in (ad), from Figure 2 (ab) It can be seen that CTF-NH2 exhibits a blocky distribution, and smaller pieces can also be observed in the image, which may be fragments of the material. When this substance is calcined at high temperature to transform into NH2-1000, from... Figure 2 (cd) It can be seen that the surface of the material is rougher. This surface feature is conducive to increasing the contact area between the material and the electrolyte, providing more electrochemical active sites for chemical reactions, and improving electrochemical performance.

[0057] Figure 3 The Fourier Transform Infrared (FT-IR) spectra of NH2-1000 and CTF-NH2 are shown in the figure. As indicated, a value of 1384 cm⁻¹ appears in the spectra of both compounds. -11648 cm -1 2355 cm -1 and 3433 cm -1 The characteristic absorption peak is at 1384 cm⁻¹. -1 and 1648 cm -1 The characteristic absorption can be attributed to the characteristic peak of the triazine group, at 2355 cm⁻¹. -1 A characteristic CO2 absorption peak appeared at 3433 cm⁻¹. -1 The presence of imine absorption characteristic peaks 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 working environment of the sodium ion anode material.

[0058] Figure 4 The figure shows the nitrogen adsorption curve of NH2-1000 at 77 K. As can be seen, the nitrogen adsorption capacity is low under low pressure conditions, and nitrogen adsorption begins at high pressure when P / P0 = 0.94. The isothermal adsorption-desorption curve of NH2-1000 is a Type-III isotherm, indicating a small interaction force between nitrogen and the adsorbent, and the presence of mesopores. Measurement results show that the specific surface area of ​​the mesopores and macropores is 2.2533 m². 2 The specific surface area of ​​the micropores is 1.1458 m² / g. 2 / g. The large specific surface area and abundant pore structure can provide more reaction sites for sodium storage reactions, thereby promoting the electrochemical performance of the material.

[0059] Figure 5 The CV curves of NH2-1000 were obtained by assembling the material into a 2025-type button cell and conducting various electrochemical tests. This paper reveals the electrochemical reaction process of NH2-1000 through cyclic voltammetry (CV) testing, and the test results are as follows. Figure 5 As shown. During the first charge and discharge process, a reduction peak appeared at 0.04 V, and a weak reduction peak appeared at 0.33 V, which can be attributed to Na. + The two-step intercalation process was observed. During the negative electrode scan, a distinct oxidation peak was observed at 0.12 V, which is likely caused by sodium ion insertion / extraction. A subsequent pair of redox peaks at 0.04 V and 0.12 V are related to sodium ion insertion / extraction from the graphite crystallites. The second and third scans showed a consistent pattern, indicating that the NH2-1000 hard carbon negative electrode material exhibits good electrochemical reversibility.

[0060] Figure 6The graph shows the rate performance of NH2-1000. NH2-1000 exhibits excellent rate performance. At current densities of 0.2, 0.5, 1, and 2 A / g, the discharge specific capacity of CTF-NH2 is 268.2, 247.7, 229.9, and 209.1 mAh / g, respectively. Even when returning to a low current density of 0.2 A / g, the specific capacity after 10 cycles is still 259.04 mAh / g, demonstrating its excellent rate performance and cycle stability.

[0061] Figure 7 After 50 cycles at a current density of 0.2 A / g, the NH2-1000 still has a battery capacity of 254.9 mAh / g. Figure 7 Another battery still had a capacity of 144.2 mAh / g after 300 cycles at a current density of 1 A / g. This result shows that the application of NH2-1000 improves battery life and provides better cycle stability.

[0062] Figure 8 The image shows an electrochemical impedance spectroscopy (EIS) test result. EIS testing is used to determine the impedance and conductivity of a battery. Based on equivalent circuit analysis, the impedance of NH2-1000 is 1.17 Ω. The EIS results indicate that the NH2-1000 hard carbon anode material has low impedance, resulting in a faster charge transfer process and 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 method for preparing an amino- and tertiary-amine-modified triazine hard carbon porous material, characterized in that, Includes the following steps: 1) Using tris(4-aminophenyl)amine and 4-amino-3,5-dibromobenzonitrile as raw materials, acetonitrile as solvent, and cuprous iodide as catalyst, the imino intermediate poly(NH2-SL) was synthesized via the Ullmann reaction; the reaction formula is as follows: ； 2) The covalent triazine framework material CTF-NH2 containing an imine structure was synthesized from NH2-SL using a tube furnace; the reaction formula is as follows: ； 3) CTF-NH2 is heated to 900-1200℃ in an argon atmosphere at a heating rate of 8-10℃ / min and reacted for 1.5-3h to obtain hard carbon porous material NH2-1000; The mesopore and macropore specific surface area of the hard carbon porous material is 2.15-2.45 m 2 / g, and the micropore specific surface area is 1.02-1.3 m 2 / g, the (002) peak position 2θ is 22°-25°, and the interlayer spacing d002 is 0.37-0.40 nm.

2. The preparation method according to claim 1, characterized in that, In step 1), the imino intermediate poly(NH2-SL) is synthesized by reacting tris(4-aminophenyl)amine and 4-amino-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.

3. The preparation method according to claim 1, characterized in that, In step 2), NH2-SL is heated to 400-480℃ in a tube furnace at a rate of 1-10℃ / min for 36-42h to undergo ionothermal polymerization, thereby synthesizing a covalent triazine framework material CTF-NH2 containing an imine structure.

4. The preparation method according to claim 1 or 3, characterized in that, In step 2), NH2-SL is heated to 450°C in a tube furnace at a rate of 1°C / min for 40 hours to undergo ionothermal polymerization, thereby synthesizing a covalent triazine framework material CTF-NH2 containing an imine structure.

5. The preparation method according to claim 1, characterized in that, CTF-NH2 was heated to 1000℃ in an argon atmosphere at a heating rate of 10℃ / min and reacted for 2 h to obtain NH2-1000.

6. The preparation method according to claim 1, 2, 3 or 5, characterized in that, The interplanar spacing d of the NH2-1000 is 0.3786 nm.

7. The preparation method according to claim 1, 2, 3 or 5, characterized in that, The mesoporous and macroporous specific surface area of ​​the NH2-1000 is 2.2533 m². 2 / g, with a microporous specific surface area of ​​1.1458 m². 2 / g.

8. A negative electrode, said negative electrode being a sodium-ion battery negative electrode, characterized in that, The hard carbon porous material prepared by the method according to any one of claims 1-7.

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