Imine covalent organic polymer, preparation method thereof, negative electrode material and potassium ion battery

Abstract

The invention provides an imine covalent organic polymer and a preparation method thereof, a negative electrode material and a potassium ion battery. The preparation method comprises the following steps: carrying out first mixing on raw materials including a carbonyl-containing first organic compound, an amino-containing second organic compound and a dispersion liquid to obtain a mixed liquid; carrying out in-situ polymerization reaction on the mixed solution to obtain an imine covalent organic polymer; wherein the first organic compound is nitro-substituted or non-substituted pyrene-4, 5, 9, 10-tetraketone; the second organic compound is selected from any one or more of C6-C12 aromatic amine compounds, C6-C12 heteroaromatic amine compounds and amino-substituted C4-C6 cyclic compounds, and the number of amino groups in each molecule of the second organic compound is greater than or equal to 2. The covalent organic polymer obtained by the preparation method can solve the problem that the structure is easily stacked and is easily dissolved in electrolyte to be damaged when the covalent organic polymer is used as a negative electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of potassium ion batteries, and in particular to an imine covalent organic polymer and a preparation method thereof, a negative electrode material, and a potassium ion battery. Background Art

[0002] Lithium-ion batteries are widely used in electronic products, new energy vehicles, and large-scale energy storage systems. However, due to the limited reserves of lithium, the cost of lithium-ion batteries remains high. Potassium has an electronic structure and electrochemical behavior similar to lithium, and its reserves are abundant and the cost is low. At the same time, potassium-ion batteries have certain advantages when paired with low-cost and multifunctional organic negative electrode materials. In recent years, the application of organic negative electrode materials in potassium-ion batteries has attracted widespread attention, but organic electrodes still have problems with low conductivity and high solubility in electrolytes. Covalent organic polymer materials are a type of two-dimensional or three-dimensional material obtained by polymerizing small organic molecules. They have the characteristics of low cost, adjustable structure, and green environmental protection. As negative electrode materials, they are more suitable for storing potassium ions with larger ionic radius. However, covalent organic polymer materials have problems such as easy structural stacking, resulting in slow kinetics, and easy solubility in electrolytes, resulting in structural destruction and loss of active substances. Summary of the Invention

[0003] The main purpose of the present invention is to provide an imine covalent organic polymer and its preparation method, negative electrode material, and potassium ion battery, so as to solve the problem in the prior art that covalent organic polymer materials used as negative electrode materials have the problem of easy stacking structure and easy dissolution in electrolyte, resulting in their structure being destroyed.

[0004] To achieve the above object, according to one aspect of the present invention, a method for preparing an imine-based covalent organic polymer is provided, the method comprising: step S1, mixing a raw material comprising a first organic compound containing a carbonyl group, a second organic compound containing an amino group, and a dispersion to obtain a mixed solution; and step S2, subjecting the mixed solution to an in-situ polymerization reaction to obtain an imine-based covalent organic polymer; wherein the first organic compound is a nitro-substituted or unsubstituted pyrene-4,5,9,10-tetraketone; and the second organic compound is selected from C6 to C 12 Aromatic amine compounds, C6~C 12 Any one or more of heteroaromatic amine compounds, amino-substituted C4-C6 ring compounds, and the number of amino groups in each molecule of the second organic compound is ≥2.

[0005] Furthermore, the second organic compound is selected from C6 aromatic amine compounds, C 12 Aromatic amine compounds, C 12Any one or more of heteroaromatic amine compounds, amino-substituted C6 ring compounds; preferably the C6 aromatic amine compound is 1,3,5-trihydroxy-2,4,6-triaminobenzene and / or 1,2-phenylenediamine; preferably C 12 The aromatic amine compound is 3,3',4,4'-tetraaminobiphenyl; preferably C 12 The heteroaromatic amine compound is 2,3,7,8-phenazinetetramine; the amino-substituted C6 ring compound is preferably 2,3,5,6-tetraaminobenzoquinone; the first organic compound is pyrene-4,5,9,10-tetraone and / or 2,7-dinitro-4,5,9,10-pyrenetetraone; and / or the molar ratio of the first organic compound to the second organic compound is 1:1 to 1:3; and / or the ratio of the total mass of the first organic compound and the second organic compound to the volume of the dispersion is 0.05 to 0.1 mg / mL.

[0006] Furthermore, the dispersion is obtained by a second mixing of mesitylene, 1,4-dioxane and acetic acid solution; wherein the volume ratio of mesitylene, 1,4-dioxane and acetic acid solution is 1 to 5:1 to 5:1; and / or, the second mixing method is ultrasonic dispersion and / or stirring, and the second mixing time is 30 to 60 minutes.

[0007] Furthermore, in the above step S1, the first mixing method is ultrasonic dispersion and / or stirring, and the first mixing time is 30 to 60 minutes.

[0008] Furthermore, the above-mentioned step S2 includes: vacuuming the mixed liquid, in-situ polymerization reaction, solid-liquid separation and drying in sequence to obtain an imine covalent organic polymer; wherein the in-situ polymerization reaction is carried out by hydrothermal means, the reaction temperature of the in-situ polymerization reaction is 60-180°C, and the reaction time of the in-situ polymerization reaction is 6-120h; and / or, the solid-liquid separation method is centrifugal separation; and / or, the drying temperature is 60-150°C, and / or, the drying time is 12-36h.

[0009] Furthermore, the structure of the imine covalent organic polymer is any one of spherical, lamellar and square; and / or the particle size of the imine covalent organic polymer is 500-800 nm; and / or the solubility of the imine covalent organic polymer in the electrolyte is 0.04-0.06 g / L, and the electrolyte is selected from any one or more of ethylene carbonate, diethyl carbonate and ethylene glycol dimethyl ether.

[0010] According to another aspect of the present invention, there is provided an imine covalent organic polymer prepared by the above-mentioned preparation method.

[0011] Furthermore, the imine covalent organic polymer is selected from

[0012] Any one or more of Represents a repeating unit.

[0013] According to another aspect of the present invention, a negative electrode material is provided. The negative electrode material includes the above-mentioned imine covalent organic polymer.

[0014] According to another aspect of the present invention, a potassium ion battery is provided, comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the negative electrode sheet comprises a negative electrode material, and the negative electrode material is the negative electrode material described above.

[0015] Applying the technical solution of the present invention, the present application forms a covalently bonded imine-type covalent organic polymer by in-situ polymerization of the carbonyl and amino groups in the above-mentioned first organic compound rich in carbonyl groups and the above-mentioned second organic compound rich in amino groups, and by adjusting the reaction temperature and reaction time to control the morphology, the stacking structure of the imine-type covalent organic polymer can be improved. The selection of heteroaromatic amine compounds and nitro-substituted pyrene-4,5,9,10-tetraone for polymerization can improve the specific capacity and rate performance of the battery. The selection of amino-substituted cyclic compounds and unsubstituted pyrene-4,5,9,10-tetraone for polymerization can improve the cycle stability and structural stability of the battery. The combination of aromatic amine compounds and heteroaromatic amine compounds can balance the capacity, conductivity and cycle stability of the battery. Compared with monomeric organic small molecules, the imine-type covalent organic polymer obtained by the above preparation method can effectively inhibit its dissolution in the electrolyte, thereby improving the structural stability of the imine-type covalent organic polymer when used as an electrode material, thereby improving the cycle stability and rate performance of the potassium ion battery. The use of the dispersion in step S1 helps the first organic compound and the second organic compound to be mixed more evenly, thereby facilitating the subsequent in-situ polymerization reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0017] Figure 1 shows an electron microscope scanning image of the TAL-PTE covalent organic polymer in Example 1 of the present application;

[0018] Figure 2 shows an electron microscope scanning image of the TAL-PTE-NO2 covalent organic polymer in Example 2 of the present application;

[0019] Figure 3A comparison chart showing the TAL-PTE covalent organic polymer of Example 1 of the present application, the TAL-PTE-NO2 covalent organic polymer of Example 2, and the negative electrode materials of Comparative Examples 1 to 3 after being dissolved in the electrolyte for 24 hours is shown;

[0020] Figure 4 The infrared spectra of TAL, PTE and TAL-PTE covalent organic polymers in Example 1 of the present application and the infrared spectra of TAL, PTE-NO2 and TAL-PTE-NO2 covalent organic polymers in Example 2 are shown. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] As analyzed in the background technology of this application, in the prior art, when covalent organic polymer materials are used as negative electrode materials, there are problems such as easy structural stacking and easy solubility in electrolyte, resulting in the destruction of their structure. In order to solve the above problems, this application provides an imine covalent organic polymer and a preparation method thereof, a negative electrode material, and a potassium ion battery.

[0023] In a typical embodiment of the present application, a method for preparing an imine-based covalent organic polymer is provided, the method comprising: step S1, mixing a raw material comprising a first organic compound containing a carbonyl group, a second organic compound containing an amino group, and a dispersion to obtain a mixed solution; and step S2, subjecting the mixed solution to an in-situ polymerization reaction to obtain an imine-based covalent organic polymer; wherein the first organic compound is a nitro-substituted or unsubstituted pyrene-4,5,9,10-tetraketone; and the second organic compound is selected from C6 to C 12 Aromatic amine compounds, C6~C 12 Any one or more of heteroaromatic amine compounds, amino-substituted C4-C6 ring compounds, and the number of amino groups in each molecule of the second organic compound is ≥2.

[0024] The present application forms a covalently bonded imine covalent organic polymer by in-situ polymerization of the carbonyl and amino groups in the first organic compound of the above-mentioned type rich in carbonyl groups and the second organic compound of the above-mentioned type rich in amino groups, and regulates the morphology by adjusting the reaction temperature and reaction time, thereby improving the stacking structure of the imine covalent organic polymer. The heteroaromatic amine compound is selected to be polymerized with nitro-substituted pyrene-4,5,9,10-tetraketone to improve the specific capacity and rate performance of the battery. The amino-substituted cyclic compound is selected to be polymerized with unsubstituted pyrene-4,5,9,10-tetraketone to improve the cycle stability and structural stability of the battery. The aromatic amine compound is used in combination with the heteroaromatic amine compound to balance the capacity, conductivity and cycle stability of the battery. Compared with monomeric organic small molecules, the imine covalent organic polymer obtained by the above preparation method can effectively inhibit its dissolution in the electrolyte, thereby improving the structural stability of the imine covalent organic polymer when used as an electrode material, thereby improving the cycle stability and rate performance of the potassium ion battery. The use of the dispersion in step S1 helps the first organic compound and the second organic compound to be mixed more evenly, thereby facilitating the subsequent in-situ polymerization reaction.

[0025] In one embodiment of the present application, the second organic compound is selected from C6 aromatic amine compounds, C 12 Aromatic amine compounds, C 12 Any one or more of heteroaromatic amine compounds, amino-substituted C6 ring compounds; preferably the C6 aromatic amine compound is 1,3,5-trihydroxy-2,4,6-triaminobenzene and / or 1,2-phenylenediamine; preferably C 12 The aromatic amine compound is 3,3',4,4'-tetraaminobiphenyl; preferably C 12 The heteroaromatic amine compound is 2,3,7,8-phenazinetetramine; the amino-substituted C6 ring compound is preferably 2,3,5,6-tetraaminobenzoquinone; the first organic compound is pyrene-4,5,9,10-tetraone and / or 2,7-dinitro-4,5,9,10-pyrenetetraone; and / or the molar ratio of the first organic compound to the second organic compound is 1:1 to 1:3; and / or the ratio of the total mass of the first organic compound and the second organic compound to the volume of the dispersion is 0.05 to 0.1 mg / mL.

[0026] Preferably, the types and molar ratios of the first organic compound and the second organic compound, as well as the ratio of the total mass of the first organic compound and the second organic compound to the volume of the dispersion are within the above ranges, which helps the carbonyl group of the first organic compound and the amino group of the second organic compound to fully contact each other, thereby helping to form a covalent bond, thereby improving the structural stability of the imine covalent organic polymer when used as an electrode material.

[0027] In addition, the molar ratio of the first organic compound to the second organic compound can be 1:1, 1:1.5, 1:2, 1:2.5 or 1:3. Of course, the molar ratio of the first organic compound to the second organic compound can be any ratio within the above range, which will not be repeated here.

[0028] The ratio of the total mass of the first organic compound and the second organic compound to the volume of the dispersion can be 0.05 mg / mL, 0.06 mg / mL, 0.07 mg / mL, 0.08 mg / mL, 0.09 mg / mL or 0.1 mg / mL. Of course, the ratio of the total mass of the first organic compound and the second organic compound to the volume of the dispersion can be any ratio within the above range, which is not repeated here.

[0029] In one embodiment of the present application, the dispersion is obtained by a second mixing of mesitylene, 1,4-dioxane and acetic acid solution; wherein the volume ratio of mesitylene, 1,4-dioxane and acetic acid solution is 1 to 5:1 to 5:1; and / or, the second mixing method is ultrasonic dispersion and / or stirring, and the second mixing time is 30 to 60 minutes.

[0030] The dispersion obtained by the above preparation method helps to better disperse the first organic compound and the second organic compound, thereby facilitating the subsequent in-situ polymerization reaction.

[0031] In one embodiment of the present application, in the above step S1, the first mixing method is ultrasonic dispersion and / or stirring, and the first mixing time is 30 to 60 minutes.

[0032] It is preferred to control the first mixing method and time within the above ranges, which helps the first organic compound and the second organic compound to be fully dispersed in the dispersion, thereby providing a good reaction environment for the subsequent polymerization reaction.

[0033] In one embodiment of the present application, the above-mentioned step S2 includes: vacuuming the mixed liquid, in-situ polymerization reaction, solid-liquid separation and drying in sequence to obtain an imine covalent organic polymer; wherein the in-situ polymerization reaction is carried out by hydrothermal means, the reaction temperature of the in-situ polymerization reaction is 60 to 180°C, and the reaction time of the in-situ polymerization reaction is 6 to 120 hours; and / or, the solid-liquid separation method is centrifugal separation; and / or, the drying temperature is 60 to 150°C, and / or, the drying time is 12 to 36 hours.

[0034] Preferably, the air in the mixed solution and the reaction vessel is exhausted by multiple vacuum evacuations to achieve a vacuum state, which facilitates the subsequent in-situ polymerization reaction. Preferably, the in-situ polymerization reaction is carried out hydrothermally, and the reaction temperature and reaction time of the in-situ polymerization reaction are controlled within the above-mentioned ranges, which facilitates full contact between the carbonyl group of the first organic compound and the amino group of the second organic compound, thereby facilitating the formation of a covalent bond and thereby improving the structural stability of the imine covalent organic polymer when used as an electrode material. Preferably, the solid-liquid separation method, drying temperature, and drying time are within the above-mentioned ranges, which facilitate the removal of residual substances in the imine covalent organic polymer, thereby improving its purity and electrochemical performance.

[0035] In addition, the reaction temperature of the in situ polymerization reaction can be 60°C, 80°C, 100°C, 120°C, 140°C, 160°C or 180°C. Of course, the reaction temperature of the in situ polymerization reaction can be any point value within the above range, which will not be repeated here.

[0036] The reaction time of the in situ polymerization reaction can be 6 h, 10 h, 25 h, 50 h, 75 h, 100 h or 120 h. Of course, the reaction time of the in situ polymerization reaction can be any point value within the above range, which will not be repeated here.

[0037] In one embodiment of the present application, the structure of the imine covalent organic polymer is any one of spherical, lamellar and square; and / or the particle size of the imine covalent organic polymer is 500-800 nm; and / or the solubility of the imine covalent organic polymer in the electrolyte is 0.04-0.06 g / L, and the electrolyte is selected from any one or more of ethylene carbonate (EC), diethyl carbonate (DEC) and ethylene glycol dimethyl ether (DME).

[0038] It is preferred that the structure and particle size of the imine-based covalent organic polymer be within the above ranges, which helps to further improve its structural stability, thereby allowing its solubility in the above electrolyte to fall within the above ranges.

[0039] In addition, the particle size of the imine covalent organic polymer can be 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm or 800 nm. Of course, the particle size of the imine covalent organic polymer can be any point value within the above range, which will not be repeated here.

[0040] The solubility of the imine covalent organic polymer in the electrolyte can be 0.04 g / L, 0.05 g / L or 0.06 g / L. Of course, the solubility of the imine covalent organic polymer in the electrolyte can be any point value within the above range, which will not be repeated here.

[0041] In another typical embodiment of the present application, an imine covalent organic polymer is provided, which is prepared by the above-mentioned preparation method.

[0042] The imine covalent organic polymer prepared by the above preparation method can effectively inhibit its dissolution in the electrolyte, thereby improving the structural stability of the imine covalent organic polymer when used as an electrode material, thereby improving the cycle stability and rate performance of the potassium ion battery.

[0043] In order to further improve the cycle stability and rate performance of potassium ion batteries, in one embodiment of the present application, the imine covalent organic polymer is selected from

[0044] Any one or more of Represents a repeating unit.

[0045] In another typical embodiment of the present application, a negative electrode material is provided. The negative electrode material includes the above-mentioned imine covalent organic polymer.

[0046] The negative electrode material comprising the above-mentioned imine covalent organic polymer has low solubility in the electrolyte and high structural stability, thereby having excellent electrochemical performance.

[0047] In another typical embodiment of the present application, a potassium ion battery is provided, comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the negative electrode sheet comprises a negative electrode material, and the negative electrode material is the negative electrode material described above.

[0048] Potassium ion batteries using the above-mentioned negative electrode materials have high capacity, good cycle stability and rate performance.

[0049] The beneficial effects of the present application will be further illustrated below with reference to examples.

[0050] Example 1

[0051] 30 mL of mesitylene, 30 mL of 1,4-dioxane, and 6 mL of 6 mol / L acetic acid solution were measured and placed in a heat-resistant glass tube container, and a second mixing was performed by ultrasonic dispersion for 30 minutes to obtain a dispersion.

[0052] 262.1 mg of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and 465.7 mg of the second organic compound 3,3′,4,4′-tetraaminobiphenyl (TAL) were added to the dispersion, and first mixing was performed by ultrasonic dispersion for 30 minutes to obtain a mixed solution.

[0053] Nitrogen was introduced into the glass tube container and vacuum was applied to discharge the gas in the glass tube container. The mixed solution was subjected to in-situ polymerization at 140°C for 96 hours by hydrothermal method. After the reaction was completed and cooled to room temperature, a precipitate was obtained by centrifugation. The precipitate was washed with ethanol, acetone and tetrahydrofuran respectively until the washing liquid was colorless. An orange solid was obtained after solid-liquid separation. Dry in a vacuum oven at 60°C for 48 hours to obtain the following: Figure 1 The chemical structure of the TAL-PTE covalent organic polymer shown is as follows:

[0054]

[0055] Example 2

[0056] 30 mL of mesitylene, 30 mL of 1,4-dioxane, and 6 mL of 6 mol / L acetic acid solution were measured and placed in a heat-resistant glass tube container, and a second mixing was performed by ultrasonic dispersion for 30 minutes to obtain a dispersion.

[0057] 352.2 mg of the first organic compound 2,7-dinitro-4,5,9,10-pyrenetetraone (PTE-NO2) and 465.7 mg of the second organic compound 3,3′,4,4′-tetraaminobiphenyl (TAL) were added to the dispersion, and first mixing was performed by ultrasonic dispersion for 30 minutes to obtain a mixed solution.

[0058] Argon was introduced into the glass tube container and vacuum was applied to discharge the gas in the glass tube container. The mixed solution was subjected to in-situ polymerization at 140°C for 96 hours by hydrothermal method. After the reaction was completed and cooled to room temperature, a precipitate was obtained by centrifugation. The precipitate was washed with ethanol, acetone and tetrahydrofuran respectively until the washing liquid was colorless. An orange solid was obtained after solid-liquid separation. Dry in a vacuum oven at 60°C for 48 hours to obtain the following: Figure 2 The chemical structure of the TAL-PTE-NO2 covalent organic polymer shown is spherical and has a particle size of 500 nm:

[0059]

[0060] Example 3

[0061] The difference from Example 1 is that the molar ratio of the first organic compound pyrene-4,5,9,10-tetraone (PTE) to the second organic compound 3,3′,4,4′-tetraaminobiphenyl (TAL) is 1:2, and a TAL-PTE covalent organic polymer is finally obtained.

[0062] Example 4

[0063] The difference from Example 1 is that the molar ratio of the first organic compound pyrene-4,5,9,10-tetraone (PTE) to the second organic compound 3,3′,4,4′-tetraaminobiphenyl (TAL) is 1:3, and a TAL-PTE covalent organic polymer is finally obtained.

[0064] Example 5

[0065] The difference from Example 1 is that the ratio of the total mass of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and the second organic compound 3,3′,4,4′-tetraaminobiphenyl (TAL) to the volume of the dispersion is 0.08 mg / mL, and a TAL-PTE covalent organic polymer is finally obtained.

[0066] Example 6

[0067] The difference from Example 1 is that the ratio of the total mass of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and the second organic compound 3,3′,4,4′-tetraaminobiphenyl (TAL) to the volume of the dispersion is 0.2 mg / mL, and a TAL-PTE covalent organic polymer is finally obtained.

[0068] Example 7

[0069] The difference from Example 1 is that the reaction temperature of the in-situ polymerization reaction is 180° C., the reaction time of the in-situ polymerization reaction is 6 h, and TAL-PTE covalent organic polymer is finally obtained.

[0070] Example 8

[0071] The difference from Example 1 is that the reaction temperature of the in-situ polymerization reaction is 50° C., the reaction time of the in-situ polymerization reaction is 125 h, and TAL-PTE covalent organic polymer is finally obtained.

[0072] Example 9

[0073] The difference from Example 1 is that 786.66 mg of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and 171.1 mg of the second organic compound 1,3,5-trihydroxy-2,4,6-triaminobenzene were added to the dispersion, and first mixing was performed by ultrasonic dispersion for 30 minutes to obtain a mixed solution, and finally an imine covalent organic polymer was obtained, whose chemical structure is as follows:

[0074]

[0075] Example 10

[0076] The difference from Example 1 is that 262.22 mg of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and 216.28 mg of the second organic compound 1,2-phenylenediamine were added to the dispersion, and first mixing was performed by ultrasonic dispersion for 30 minutes to obtain a mixed solution, and finally an imine covalent organic polymer was obtained, whose chemical structure is as follows:

[0077]

[0078] Example 11

[0079] The difference from Example 1 is that 262.22 mg of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and 480.54 mg of the second organic compound 2,3,7,8-phenazinetetramine were added to the dispersion, and first mixing was performed by ultrasonic dispersion for 30 minutes to obtain a mixed solution, and finally an imine covalent organic polymer was obtained, whose chemical structure is as follows:

[0080]

[0081] Example 12

[0082] The difference from Example 1 is that 262.22 mg of the first organic compound pyrene-4,5,9,10-tetraone (PTE) and 336.32 mg of the second organic compound 2,3,5,6-tetraaminobenzoquinone were added to the dispersion, and first mixing was performed by ultrasonic dispersion for 30 minutes to obtain a mixed solution, and finally an imine covalent organic polymer was obtained, whose chemical structure is as follows:

[0083]

[0084] Example 13

[0085] The difference from Example 1 is that the imine covalent organic polymer is a combination of TAL-PTE covalent organic polymer and TAL-PTE-NO2 covalent organic polymer, and the mass ratio of TAL-PTE covalent organic polymer to TAL-PTE-NO2 covalent organic polymer is 1:1.2.

[0086] Comparative Example 1

[0087] TAL was directly used as the negative electrode material.

[0088] Comparative Example 2

[0089] PTE was directly used as the negative electrode material.

[0090] Comparative Example 3

[0091] PTE-NO2 was directly used as the negative electrode material.

[0092] Test method:

[0093] Electrochemical performance tests were conducted on the imine-based covalent organic polymers used as negative electrode materials in the above examples and the negative electrode materials in the comparative examples. The following test method was used: the negative electrode material, the conductive agent acetylene black, and the binder PVDF were mixed in 10 mL of N-methylpyrrolidone at a mass ratio of 9:0.5:0.5. The mixture was stirred thoroughly to form a slurry, which was then coated onto the surface of aluminum foil using a coating machine, dried, and cut. Potassium ion batteries were assembled in an argon-protected glove box using a potassium sheet as the positive electrode and LX-146:KFSI / DME (ethylene glycol dimethyl ether) as the electrolyte. Coin cells (CR2032 type) were used to construct the batteries. Electrochemical performance tests were conducted at room temperature within a voltage range of 0.01 to 3 V at 25°C. The test results are shown in Table 1.

[0094] The solubility of the imine covalent organic polymers of the above examples and the monomer molecules of the comparative example were tested in the electrolyte. The test results are shown in Table 1.

[0095] Table 1

[0096]

[0097] in, Figure 3 The TAL-PTE covalent organic polymer of Example 1, the TAL-PTE-NO2 covalent organic polymer of Example 2 and the negative electrode materials of Comparative Examples 1 to 3 are compared after being dissolved in the electrolyte for 24 hours. Figure 3 It can be seen that compared with TAL, PTE, and PTE-NO2 organic small molecules, TAL-PTE covalent organic polymers and TAL-PTE-NO2 covalent organic polymers have lower solubility in the electrolyte, or even do not dissolve.

[0098] Figure 4 The infrared spectra of TAL, PTE and TAL-PTE covalent organic polymers in Example 1, and the infrared spectra of TAL, PTE-NO2 and TAL-PTE-NO2 covalent organic polymers in Example 2 are shown. Figure 4 It can be seen that after the polymerization of organic small molecules, C=O disappears and C=N (1195cm -1 ) is generated, thereby forming TAL-PTE covalent organic polymer and TAL-PTE-NO2 covalent organic polymer. In addition, the infrared spectrum of TAL-PTE-NO2 covalent organic polymer is also detected at 1589cm -1 Therefore, the results of infrared tests prove the successful polymerization between organic small molecules.

[0099] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0100] The present application forms a covalently bonded imine covalent organic polymer by in-situ polymerization of the carbonyl and amino groups in the first organic compound of the above-mentioned type rich in carbonyl groups and the second organic compound of the above-mentioned type rich in amino groups, and regulates the morphology by adjusting the reaction temperature and reaction time, thereby improving the stacking structure of the imine covalent organic polymer. The heteroaromatic amine compound is selected to be polymerized with nitro-substituted pyrene-4,5,9,10-tetraketone to improve the specific capacity and rate performance of the battery. The amino-substituted cyclic compound is selected to be polymerized with unsubstituted pyrene-4,5,9,10-tetraketone to improve the cycle stability and structural stability of the battery. The aromatic amine compound is used in combination with the heteroaromatic amine compound to balance the capacity, conductivity and cycle stability of the battery. Compared with monomeric organic small molecules, the imine covalent organic polymer obtained by the above preparation method can effectively inhibit its dissolution in the electrolyte, thereby improving the structural stability of the imine covalent organic polymer when used as an electrode material, thereby improving the cycle stability and rate performance of the potassium ion battery. The use of the dispersion in step S1 helps the first organic compound and the second organic compound to be mixed more evenly, thereby facilitating the subsequent in-situ polymerization reaction.

[0101] The above are merely embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing an imine covalent organic polymer, characterized in that: The preparation method comprises: Step S1, performing a first mixing of raw materials including a first organic compound containing a carbonyl group, a second organic compound containing an amino group, and a dispersion liquid to obtain a mixed liquid; and Step S2, subjecting the mixed solution to an in-situ polymerization reaction to obtain an imine-based covalent organic polymer; wherein the first organic compound is nitro-substituted or unsubstituted pyrene-4,5,9,10-tetraone; The second organic compound is selected from C6 to C 12 Aromatic amine compounds, C6~C 12 Any one or more of heteroaromatic amine compounds and amino-substituted C4-C6 ring compounds, wherein the number of amino groups in each molecule of the second organic compound is ≥2.

2. The preparation method according to claim 1, characterized in that The second organic compound is selected from C6 aromatic amine compounds, C 12 Aromatic amine compounds, C 12 Any one or more of heteroaromatic amine compounds and amino-substituted C6 ring compounds; Preferably, the C6 aromatic amine compound is 1,3,5-trihydroxy-2,4,6-triaminobenzene and / or 1,2-phenylenediamine; Preferably, the C 12 The aromatic amine compound is 3,3',4,4'-tetraaminobiphenyl; Preferably, the C 12 The heteroaromatic amine compound is 2,3,7,8-phenazinetetramine; Preferably, the amino-substituted C6 ring compound is 2,3,5,6-tetraaminobenzoquinone; The first organic compound is pyrene-4,5,9,10-tetraone and / or 2,7-dinitro-4,5,9,10-pyrenetetraone; and / or, the molar ratio of the first organic compound to the second organic compound is 1:1 to 1:3; and / or, the ratio of the total mass of the first organic compound and the second organic compound to the volume of the dispersion is 0.05 to 0.1 mg / mL.

3. The preparation method according to claim 1 or 2, characterized in that The dispersion is obtained by secondly mixing mesitylene, 1,4-dioxane and acetic acid solution; The volume ratio of mesitylene, 1,4-dioxane and acetic acid solution is 1-5:1-5:1; and / or the second mixing method is ultrasonic dispersion and / or stirring, and the second mixing time is 30-60 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that In the step S1, the first mixing method is ultrasonic dispersion and / or stirring, and the first mixing time is 30 to 60 minutes.

5. The preparation method according to any one of claims 1 to 4, characterized in that The step S2 comprises: The mixed liquid is sequentially subjected to vacuuming, the in-situ polymerization reaction, solid-liquid separation and drying to obtain the imine covalent organic polymer; The in-situ polymerization reaction is carried out hydrothermally, the reaction temperature of the in-situ polymerization reaction is 60 to 180° C., and the reaction time of the in-situ polymerization reaction is 6 to 120 hours. And / or, the solid-liquid separation method is centrifugal separation; and / or, the drying temperature is 60 to 150° C., and / or, the drying time is 12 to 36 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that The structure of the imine covalent organic polymer is any one of spherical, lamellar and square; and / or the particle size of the imine covalent organic polymer is 500-800 nm; and / or the solubility of the imine covalent organic polymer in the electrolyte is 0.04-0.06 g / L, and the electrolyte is selected from any one or more of ethylene carbonate, diethyl carbonate and ethylene glycol dimethyl ether.

7. An imine covalent organic polymer, characterized in that The method is prepared according to any one of claims 1 to 6.

8. The imine covalent organic polymer according to claim 7, characterized in that The imine covalent organic polymer is selected from Any one or more of Represents a repeating unit.

9. A negative electrode material, characterized in that The negative electrode material includes the imine covalent organic polymer according to claim 8.

10. A potassium ion battery comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the negative electrode sheet comprises a negative electrode material, characterized in that: The negative electrode material is the negative electrode material according to claim 9.

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