Metal-doped three-dimensional covalent organic framework material, preparation method thereof, negative electrode with the material and secondary battery with the negative electrode

Abstract

This invention relates to a metal-doped three-dimensional covalent organic framework material, formed by linking a 9,10-dihydro-9,10-[1,2]benzanthracene framework and a metal-doped β-tetraroxyporphyrin framework via nitrogen atoms. The 9,10-dihydro-9,10-[1,2]benzanthracene framework includes two first-dimensional linking sites, two second-dimensional linking sites, and two third-dimensional linking sites. For any 9,10-dihydro-9,10-[1,2]benzanthracene framework, at least one first-dimensional linking site is connected to a nitrogen atom via a double bond, at least one second-dimensional linking site is connected to a nitrogen atom via a double bond, and at least one third-dimensional linking site is connected to a nitrogen atom via a double bond. The four R groups of the metal-doped β-tetraroxyporphyrin framework are each connected to a nitrogen atom via a single bond. The metal includes one of cerium, iridium, platinum, and gold. The material of this invention can shorten the mass transfer path, reduce charge hindrance, improve the conductivity and catalytic activity of the material, accelerate proton conduction, and enhance mass transfer reaction kinetics, providing a highly efficient catalytic platform for electrochemical reactions.

Description

Technical Field

[0001] This invention relates to the field of chemically functional composite materials, and in particular to metal-doped three-dimensional covalent organic framework materials, their preparation methods, a negative electrode having the material, and a secondary battery having the negative electrode. Background Technology

[0002] Covalent organic frameworks (COFs) are a class of porous framework compounds composed of small organic molecules linked by strong covalent bonds. In recent years, COFs have become a research hotspot in novel battery materials due to their advantages such as designable pore parameters, strong thermochemical stability, and designable region electron enrichment properties. With in-depth research on three-dimensional framework molecules, a research branch of three-dimensional COFs has emerged. Compared to two-dimensional COFs, three-dimensional COFs can establish unique three-dimensional porous structures, bringing higher mass transfer efficiency and more catalytic sites to heterogeneous catalytic processes, and showing promising research prospects.

[0003] However, there is relatively little research on three-dimensional COFs materials. There is no research on three-dimensional COFs materials formed by connecting cerium, iridium, platinum, and gold-doped porphyrin molecules with 9,10-dihydro-9,10-[1,2]benzanthracene, as well as their electrode and battery performance. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide a metal-doped three-dimensional covalent organic framework material, in which 9,10-dihydro-9,10-[1,2]benzanthracene and β-tetrasubstituted porphyrins doped with third transition metals such as cerium, iridium, platinum, and gold are directly linked through nitrogen atoms to form a three-dimensional covalent organic framework material. This not only shortens the mass transfer path between the two molecules and reduces charge hindrance, but also makes full use of the unique advantages of the 4f and 5d orbitals of cerium, iridium, platinum, and gold to improve the conductivity and catalytic activity of the material, accelerate proton conduction, enhance mass transfer reaction kinetics, and provide a highly efficient catalytic platform for electrochemical reactions.

[0005] The three-dimensional COF material of this invention constructs a through-hole porous network structure. This network structure not only provides a stable mass transfer path but also effectively promotes multi-scale ion transport through its point-line transport mechanism. This ordered pore design makes the transport of protons, lithium ions, etc., in the electrochemical system more efficient, reduces charge hindrance, and enhances the overall kinetic performance of the mass transfer reaction.

[0006] This invention utilizes β-tetraramine-based porphyrins and 9,10-dihydro-9,10-[1,2]benzanthracene doped with cerium (Ce), iridium (Ir), platinum (Pt), or gold (Au) as monomers to synthesize covalent organic frameworks (COFs), which offer significant advantages, particularly in mass transfer coupling and proton hybridization. Doping Ce, Ir, Pt, and Au into the β-tetraramine-based porphyrin framework to form COF materials further enhances the conductivity and electrochemical activity of the COF materials. When these metal-doped COF materials are modified onto lithium metal anodes, they not only uniformly distribute lithium ion deposition but also effectively suppress lithium dendrite growth, thereby improving the cycle performance and safety of lithium metal batteries. Under the influence of the 5d and 4f orbitals, metals such as Ce, Ir, Pt, and Au not only exhibit significant advantages in proton-coupled electron transfer reactions but also demonstrate outstanding performance in catalytic kinetics. Doping Ce, Ir, Pt, and Au into the β-tetrarroline porphyrin framework to form COF materials can not only effectively improve the conductivity and catalytic activity of the materials, but also significantly accelerate proton conduction and enhance mass transfer reaction kinetics. Specifically, the 4f orbital of cerium (Ce) has a highly localized electronic structure, exhibiting significant electron transport capabilities in proton coupling. 3+ and Ce 4+ The redox cycle provides a stable charge transfer channel, further enhancing proton transport and coupling efficiency. Iridium's partially filled 5d orbitals exhibit excellent catalytic performance in proton hybridization, strengthening charge transfer and proton coupling. Platinum's half-filled 5d orbitals provide a stable and efficient proton transport pathway, suitable for kinetic acceleration in mass transfer reactions. Gold's vacant 5d orbitals give it high stability in proton coupling reactions, especially exhibiting outstanding catalytic performance in highly electrochemically stable environments.

[0007] The technical solution of the present invention is achieved in the following ways:

[0008] A metal-doped three-dimensional covalent organic framework material is formed by linking a 9,10-dihydro-9,10-[1,2]benzanthracene framework and a metal-doped β-tetraroxyporphyrin framework via nitrogen atoms. The 9,10-dihydro-9,10-[1,2]benzanthracene framework includes two first-dimensional linking sites, two second-dimensional linking sites, and two third-dimensional linking sites. For any 9,10-dihydro-9,10-[1,2]benzanthracene framework, at least one first-dimensional linking site is connected to the nitrogen atom via a double bond, at least one second-dimensional linking site is connected to the nitrogen atom via a double bond, and at least one third-dimensional linking site is connected to the nitrogen atom via a double bond. The four R groups of the metal-doped β-tetraroxyporphyrin framework are each connected to one nitrogen atom via a single bond. The metal includes one of cerium, iridium, platinum, and gold.

[0009] The metal-doped three-dimensional covalent organic framework material of this invention allows 9,10-dihydro-9,10-[1,2]benzanthracene to be directly linked with β-tetrasubstituted porphyrins doped with third transition metals such as cerium, iridium, platinum, and gold through nitrogen atoms to form a three-dimensional covalent organic framework material. This not only shortens the mass transfer path between the two molecules and reduces charge hindrance, but also fully utilizes the unique advantages of the 4f and 5d orbitals of cerium, iridium, platinum, and gold to improve the conductivity and catalytic activity of the material, accelerate proton conduction, and enhance mass transfer reaction kinetics, providing a highly efficient catalytic platform for electrochemical reactions.

[0010] Furthermore, the structural formula of the metal-doped three-dimensional covalent organic framework material is as follows:

[0011]

[0012] M is one of cerium, iridium, platinum, and gold. The R group is selected as phenyl, which further enhances the π-conjugated system of the metal-doped β-tetrarporphyrin framework, improves the electron transport rate, and improves the conductivity and ionic conductivity of the obtained three-dimensional covalent organic framework material; all six connection sites of the 9,10-dihydro-9,10-[1,2]benzanthracene framework are connected to the porphyrin framework, which increases the molecular distribution density of the covalent organic framework material, improves the mass transfer efficiency, and brings more catalytic sites.

[0013] The present invention also provides a method for preparing any of the above-mentioned metal-doped three-dimensional covalent organic framework materials, comprising the following steps: mixing metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin with a three-dimensional ketone compound, glacial acetic acid solution and a first solvent, degassing, reacting at 100-150℃ for 72-120 h, filtering, washing and drying to obtain the metal-doped three-dimensional covalent organic framework material;

[0014] The metal is one of cerium, iridium, platinum, and gold; the three-dimensional ketone compound is formed by the 9,10-dihydro-9,10-[1,2]benzanthracene skeleton and at least three oxygen atoms connected by double bonds, wherein at least one first-dimensional linking site is connected to the oxygen atom, at least one second-dimensional linking site is connected to the oxygen atom, and at least one third-dimensional linking site is connected to the oxygen atom; the first solvent includes one or more of methanol, pyridine, N-methylpyrrolidone, o-dichlorobenzene, n-butanol, mesitylene, and 1,4-dioxane.

[0015] Further, the three-dimensional ketone compound is 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone.

[0016] Furthermore, the molar ratio of the ketone carbonyl group in the three-dimensional ketone compound to the amino group in the metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin is 1:(1 to 1.2).

[0017] Further, the sum of the masses of the three-dimensional ketone compound and the metal-doped 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is: the volume of the first solvent = 20 mg : (1-2) ml, the volume ratio of the first solvent to the glacial acetic acid solution is 1 : (0.1-0.2), and the concentration of the glacial acetic acid solution is 6-12 mol / L.

[0018] The present invention also provides a negative electrode comprising an active metal and any of the metal-doped three-dimensional covalent organic framework materials described above, wherein the active metal comprises one or more of lithium, sodium, potassium, and zinc.

[0019] Furthermore, the method for preparing the negative electrode includes the following steps: uniformly dispersing the metal-doped three-dimensional covalent organic framework material in a second solvent to obtain a mixed solution; uniformly drop-coating the mixed solution onto the surface of the active metal; and heating the active metal until the second solvent on the surface of the active metal completely evaporates to obtain the negative electrode.

[0020] The mass of the metal-doped three-dimensional covalent organic framework material: the volume of the second solvent = 1 mg: (1-3) mL;

[0021] The amount of the mixed solution dropped onto the active metal surface is 0.17-0.28 μL / mm. 2 If the dosage is less than 0.17 μL / mm 2 If the contact area between the mixed solution and the active metal surface is too small, the metal sheet will not be completely covered. If the dosage is greater than 0.28 μL / mm 2 The mixed solution will overflow the area on the active metal surface that needs to be coated, resulting in material waste.

[0022] Furthermore, the method for preparing the negative electrode also includes the following steps: heating the active metal at a temperature of 40-80°C for a time of 4-12 hours.

[0023] The present invention also provides a secondary battery, comprising a battery casing and any of the above-described negative electrode, lithium iron phosphate positive electrode, separator and electrolyte located within the battery casing, wherein the separator is located between the positive electrode and the negative electrode.

[0024] Compared with the prior art, the technical advantages of the present invention are as follows:

[0025] (1) This invention provides four different combinations of metal porphyrin-three-dimensional ketone monomers to prepare COF materials with excellent electrochemical performance, which significantly improves the cycle stability and capacity retention of lithium metal secondary batteries.

[0026] Specifically, 9,10-dihydro-9,10-[1,2]benzanthracene is directly linked with β-tetrasubstituted porphyrins doped with third transition metals such as cerium, iridium, platinum, and gold through nitrogen atoms to form a three-dimensional covalent organic framework material. This not only shortens the mass transfer path between the two molecules and reduces charge hindrance, but also fully utilizes the unique advantages of the 4f and 5d orbitals of cerium, iridium, platinum, and gold to enhance the conductivity and catalytic activity of the material, accelerate proton conduction, and strengthen mass transfer reaction kinetics, providing a highly efficient catalytic platform for electrochemical reactions. By adjusting the electronegativity and electron cloud density of the COF framework, the adsorption capacity and migration efficiency of lithium ions are improved, and the growth of lithium dendrites is effectively suppressed, thereby improving the cycle life of the battery.

[0027] The COF design of this invention utilizes the synergistic effect of ketone monomers and transition metal coordination centers, which not only optimizes the electronic structure of the COF framework but also optimizes the electrolyte decomposition process. This facilitates the formation of a uniform and dense SEI film, reduces lithium dendrite growth, extends battery cycle life, and improves safety.

[0028] (2) The strong π-conjugated system contained in β-tetrasubstituted porphyrins doped with third transition metals such as cerium, iridium, platinum and gold combines with the porous framework of three-dimensional COF, which on the one hand significantly improves the electron transport rate and promotes the conductivity and ion conductivity of three-dimensional COF materials; on the other hand, it regulates the formation and stability of the solid electrolyte interface (SEI) film in lithium metal batteries through its electronic structure; furthermore, the metal centers in β-tetrasubstituted porphyrins doped with third transition metals such as cerium, iridium, platinum and gold can provide a variety of redox active sites, which help accelerate the catalytic process and improve the overall energy conversion efficiency.

[0029] (3) Using 5,10,15,20-tetra(4-aminophenyl)porphyrin cerium, 5,10,15,20-tetra(4-aminophenyl)porphyrin iridium, 5,10,15,20-tetra(4-aminophenyl)porphyrin platinum, and 5,10,15,20-tetra(4-aminophenyl)porphyrin gold as amino monomers for COF, the electrochemical performance, ionic conductivity, mechanical stability, and thermal stability of COF materials can be significantly enhanced through the unique electronic structure and redox activity of metalloporphyrins. These advantages make the synthesized COF materials very suitable for application in lithium metal batteries.

[0030] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the basic structure of a metal-doped three-dimensional covalent organic framework material according to an embodiment of the present invention;

[0032] Figure 2 This is a TEM image of a metal-doped three-dimensional covalent organic framework material according to an embodiment of the present invention;

[0033] Figure 3 The nitrogen adsorption-desorption curve of the metal-doped three-dimensional covalent organic framework material according to an embodiment of the present invention is shown below.

[0034] Figure 4 This is a pore size distribution diagram of a metal-doped three-dimensional covalent organic framework material according to an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the basic structure of the metal-doped three-dimensional covalent organic framework material described in a pair of proportions of the present invention. Detailed Implementation

[0036] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0037] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0038] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0039] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0040] It should be understood that the embodiments of this application are not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from their scope. The scope of the embodiments of this application is limited only by the appended claims.

[0041] It should be noted that the 9,10-dihydro-9,10-[1,2]benzanthracene skeleton described in this invention is composed of 9,10-dihydro-9,10-[1,2]benzanthracene and two first-dimensional linking sites, two second-dimensional linking sites, and two third-dimensional linking sites. The two first-dimensional linking sites described in this invention refer to the carbons at positions 2 and 3 of 9,10-dihydro-9,10-[1,2]benzanthracene. The two second-dimensional linking sites described in this invention refer to the carbons at positions 6 and 7 of 9,10-dihydro-9,10-[1,2]benzanthracene. The two third-dimensional linking sites described in this invention refer to the carbons at positions 14 and 15 of 9,10-dihydro-9,10-[1,2]benzanthracene.

[0042] It should be noted that the metal-doped β-tetrarhophyllite framework described in this invention is formed by replacing the hydrogen atoms on the four β-position carbons of porphyrin (corresponding to the carbons at positions 5, 10, 15, and 20 of porphyrin) with R groups and doping with metal M. In this invention, M refers to any metal, and the specific metal corresponding to M in different substances / structures should be based on the examples exemplified in this invention.

[0043] The metal-doped three-dimensional covalent organic framework material of the present invention allows 9,10-dihydro-9,10-[1,2]benzanthracene to be directly linked with β-tetrasubstituted porphyrins doped with third transition metals such as cerium, iridium, platinum, and gold through nitrogen atoms to form a three-dimensional covalent organic framework material. This not only shortens the mass transfer path between the two molecules and reduces charge hindrance, but also makes full use of the unique advantages of the 4f and 5d orbitals of cerium, iridium, platinum, and gold to improve the conductivity and catalytic activity of the material, accelerate proton conduction, and enhance mass transfer reaction kinetics, providing a highly efficient catalytic platform for electrochemical reactions.

[0044] Furthermore, the structural formula of the metal-doped three-dimensional covalent organic framework material is as follows:

[0045]

[0046] M is one of cerium, iridium, platinum, and gold. The R group is selected as phenyl, which further enhances the π-conjugated system of the metal-doped β-tetrarporphyrin framework, improves the electron transport rate, and improves the conductivity and ionic conductivity of the obtained three-dimensional covalent organic framework material; all six connection sites of the 9,10-dihydro-9,10-[1,2]benzanthracene framework are connected to the porphyrin framework, which increases the molecular distribution density of the covalent organic framework material, improves the mass transfer efficiency, and brings more catalytic sites.

[0047] The present invention also provides a method for preparing any of the above-mentioned metal-doped three-dimensional covalent organic framework materials, comprising the following steps: mixing metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin with a three-dimensional ketone compound, glacial acetic acid solution and a first solvent, degassing, reacting at 100-150℃ for 72-120 h, filtering, washing and drying to obtain the metal-doped three-dimensional covalent organic framework material;

[0048] The metal is one of cerium, iridium, platinum, and gold; the three-dimensional ketone compound is formed by the 9,10-dihydro-9,10-[1,2]benzanthracene skeleton and at least three oxygen atoms connected by double bonds, wherein at least one first-dimensional linking site is connected to the oxygen atom, at least one second-dimensional linking site is connected to the oxygen atom, and at least one third-dimensional linking site is connected to the oxygen atom; the first solvent includes one or more of methanol, pyridine, N-methylpyrrolidone, o-dichlorobenzene, n-butanol, mesitylene, and 1,4-dioxane.

[0049] Further, the three-dimensional ketone compound is 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone.

[0050] Furthermore, the molar ratio of the ketone carbonyl group in the three-dimensional ketone compound to the amino group in the metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin is 1:(1 to 1.2).

[0051] Further, the sum of the masses of the three-dimensional ketone compound and the metal-doped 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is: the volume of the first solvent = 20 mg : (1-2) ml, the volume ratio of the first solvent to the glacial acetic acid solution is 1 : (0.1-0.2), and the concentration of the glacial acetic acid solution is 6-12 mol / L.

[0052] The present invention also provides a negative electrode comprising an active metal and any of the metal-doped three-dimensional covalent organic framework materials described above, wherein the active metal comprises one or more of lithium, sodium, potassium, and zinc.

[0053] Furthermore, the method for preparing the negative electrode includes the following steps: uniformly dispersing the metal-doped three-dimensional covalent organic framework material in a second solvent to obtain a mixed solution; uniformly drop-coating the mixed solution onto the surface of the active metal; and heating the active metal until the second solvent on the surface of the active metal completely evaporates to obtain the negative electrode.

[0054] The mass of the metal-doped three-dimensional covalent organic framework material: the volume of the second solvent = 1 mg: (1-3) mL;

[0055] The amount of the mixed solution dropped onto the active metal surface is 0.17-0.28 μL / mm. 2 If the dosage is less than 0.17 μL / mm 2 If the contact area between the mixed solution and the active metal surface is too small, the metal sheet will not be completely covered. If the dosage is greater than 0.28 μL / mm 2 The mixed solution will overflow the area on the active metal surface that needs to be coated, resulting in material waste.

[0056] Furthermore, the method for preparing the negative electrode also includes the following steps: heating the active metal at a temperature of 40-80°C for a time of 4-12 hours.

[0057] The present invention also provides a secondary battery comprising a battery casing and any of the above-described negative electrode, lithium iron phosphate positive electrode, separator, and electrolyte located within the battery casing, wherein the separator is located between the positive electrode and the negative electrode.

[0058] The physical properties and testing methods of the embodiments or comparative examples of the present invention are as follows:

[0059] The method for testing pore distribution according to the present invention includes the following steps: nitrogen adsorption-desorption experiment is carried out using a BELSORP-mini device at 77K; the adsorption-desorption curve is analyzed by the Brunauer-Emmet-Teller (BET) method; the specific surface area of ​​the sample is calculated; and the desorption curve is analyzed by the Barrett-Joyner-Halenda (BJH) method to obtain the pore size distribution curve of the material.

[0060] The method for testing Young's modulus according to the present invention includes the following steps: after selecting a material sample, the Young's modulus is measured using an atomic force microscope (AFM); specifically, an RTESP-525 AFM equipped with a silicon probe (manufactured by Bruker) is used, and the test data is analyzed using the Derjaguin-Muller-Toporov (DMT) model in NanoScopeAnalysis software.

[0061] Example 1

[0062] This embodiment provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0063] 121.9365 mg (0.15 mmol) of 5,10,15,20-tetratetra(4-aminophenyl)porphyrin cerium and 34.482 mg (0.1 mmol) of 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 1 In this embodiment, the metal M is cerium.

[0064] The transmission electron microscope (TEM) image of the metal-doped three-dimensional covalent organic framework material prepared in this embodiment is shown below. Figure 2 As shown. By Figure 2 It can be seen that metal-doped three-dimensional covalent organic framework materials have a sheet-like structure.

[0065] The nitrogen adsorption-desorption curves of the metal-doped three-dimensional covalent organic framework material prepared in this embodiment are as follows: Figure 3 As shown, the pore size distribution of the metal-doped three-dimensional covalent organic framework material prepared in this embodiment is as follows. Figure 4 As shown in the figure. The results indicate that the metal-doped three-dimensional covalent organic framework material in Example 1 has a large specific surface area and a pore size range of 0-12 nanometers, concentrated in the range of 2-4 nanometers. This porous structure helps to accelerate ion transport and provides a solid foundation for improving the electrochemical performance of the material.

[0066] After measuring the Young's modulus of the metal-doped three-dimensional covalent organic framework material prepared in this embodiment, the results showed that the surface Young's modulus of the metal-doped three-dimensional covalent organic framework material reached 17 GPa. The Young's modulus range of two-dimensional covalent organic frameworks (2DCOFs) is 4 to 24 GPa. The value of 17 GPa is relatively high among covalent organic framework (COF) materials, and it has significant mechanical property advantages even compared with traditional engineering materials, exhibiting excellent mechanical strength. This high strength characteristic is crucial for suppressing dendrite growth in lithium metal anodes during charge and discharge processes, as good mechanical properties help disperse stress concentration, thereby reducing dendrite formation and growth. Specifically, in battery applications, this high Young's modulus helps improve battery safety and stability, especially when operating at high current densities, effectively preventing problems such as battery short circuits and thermal runaway. Therefore, the high Young's modulus of this COF material is a significant advantage as a battery anode material.

[0067] This embodiment also provides a composite negative electrode for metal secondary batteries, the preparation method of which includes the following steps:

[0068] 10 mg of the aforementioned metal-doped three-dimensional covalent organic framework material was uniformly dispersed in 10 mL of N-methylpyrrolidone to form a homogeneous mixed solution. In an argon-filled glove box (where the concentrations of water and oxygen were below 0.01 ppm), 30 μL of the solution was dropped onto a 15 mm diameter lithium metal sheet. The lithium metal sheet with the solution was then placed on a heating stage at 60 °C and heated for 6 hours to evaporate the solvent. After complete solvent evaporation and cooling to ambient temperature, a composite negative electrode for metal secondary batteries was obtained.

[0069] This embodiment also provides a Li||Li symmetric battery, the preparation method of which includes the following steps: using the aforementioned composite negative electrode for metal secondary batteries as the counter electrode and a lithium metal sheet as the working electrode, a Li||Li symmetric battery of model CR2032 is assembled. The separator used in the battery is a Celgard 2400 polypropylene microporous membrane, and the electrolyte is 1 mol / L LiTFSI / DOL+DME (V / V = 1:1).

[0070] This embodiment also provides a lithium iron phosphate metal secondary battery, the preparation method of which includes the following steps:

[0071] Lithium iron phosphate, superconducting carbon black (SuperP) conductive agent, and polyvinylidene fluoride (PVDF) binder were weighed and mixed in a mass ratio of 8:1:1. Then, N-methylpyrrolidone (NMP) at 19 times the mass of PVDF was added and thoroughly stirred into a paste. This paste was then coated onto aluminum foil current collectors using a spatula and dried in a vacuum oven at 60°C for 8 hours. The resulting electrode (φ = 15 mm) was cut to obtain an electrode with an active material loading of 4 mg, which served as the positive electrode for the metal secondary battery. Next, the positive electrode and the aforementioned composite negative electrode for the metal secondary battery were transferred to an argon-filled glove box for assembling coin cells. The coin cell model was CR2032, the separator was a polypropylene microporous membrane Celgard2400, and the electrolyte was 1 mol / L LiPF6 / EC+DMC+EMC (V:V:V = 1:1:1).

[0072] Example 2

[0073] This embodiment provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0074] 129.752 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin iridium and 34.482 mg (0.1 mmol) of 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 1 In this embodiment, the metal M is iridium.

[0075] This embodiment also provides a composite negative electrode for metal secondary batteries. The difference from Embodiment 1 is that the metal-doped three-dimensional covalent organic framework material is the same as that in Embodiment 1. The preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0076] This embodiment also provides a Li||Li symmetric battery. The difference from Embodiment 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this embodiment. Its preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0077] This embodiment also provides a lithium iron phosphate metal secondary battery. The difference from Embodiment 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this embodiment. Its preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0078] Example 3

[0079] This embodiment provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0080] 130.181 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin platinum and 34.482 mg (0.1 mmol) of 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 1 In this embodiment, metal M is platinum.

[0081] This embodiment also provides a composite negative electrode for metal secondary batteries. The difference from Embodiment 1 is that the metal-doped three-dimensional covalent organic framework material is the same as that in Embodiment 1. The preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0082] This embodiment also provides a Li||Li symmetric battery. The difference from Embodiment 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this embodiment. Its preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0083] This embodiment also provides a lithium iron phosphate metal secondary battery. The difference from Embodiment 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this embodiment. Its preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0084] Example 4

[0085] This embodiment provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0086] 130.464 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin gold and 34.482 mg (0.1 mmol) of 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 1 In this embodiment, the metal M is gold.

[0087] This embodiment also provides a composite negative electrode for metal secondary batteries. The difference from Embodiment 1 is that the metal-doped three-dimensional covalent organic framework material is the same as that in Embodiment 1. The preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0088] This embodiment also provides a Li||Li symmetric battery. The difference from Embodiment 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this embodiment. Its preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0089] This embodiment also provides a lithium iron phosphate metal secondary battery. The difference from Embodiment 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this embodiment. Its preparation method is the same as that in Embodiment 1, so it will not be described in detail.

[0090] Comparative Example 1

[0091] This comparative example provides a lithium metal sheet negative electrode for use in metal secondary batteries.

[0092] This comparative example also provides a Li||Li symmetric battery. The difference from Example 1 is that the lithium metal sheet anode of this comparative example is used instead of the composite anode for metal secondary batteries described in Example 1. The preparation method is the same as that of Example 1, so it will not be described in detail.

[0093] This comparative example also provides a lithium iron phosphate metal secondary battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery uses the lithium metal sheet negative electrode of this comparative example. Its preparation method is the same as that of Example 1, so it will not be described in detail.

[0094] Comparative Example 2

[0095] This comparative example provides a three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0096] 101.219 mg (0.15 mmol) of 5,10,15,20-tetratetra(4-aminophenyl)porphyrin and 34.482 mg (0.1 mmol) of 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 1 The difference lies in the absence of metal M.

[0097] This comparative example also provides a composite negative electrode for metal secondary batteries. The difference from Example 1 is that the metal-doped three-dimensional covalent organic framework material used is the three-dimensional covalent organic framework material of this comparative example. Its preparation method is the same as that of Example 1, so it will not be described in detail.

[0098] This comparative example also provides a Li||Li symmetric battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0099] This comparative example also provides a lithium iron phosphate metal secondary battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0100] Comparative Example 3

[0101] This comparative example provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0102] 109.7235 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin nickel and 34.482 mg (0.1 mmol) of 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 1 The difference is that the metal M in this comparative example is nickel.

[0103] This comparative example also provides a composite negative electrode for metal secondary batteries. The difference from Example 1 is that the metal-doped three-dimensional covalent organic framework material used is the metal-doped three-dimensional covalent organic framework material of this comparative example. Its preparation method is the same as that of Example 1, so it will not be described in detail.

[0104] This comparative example also provides a Li||Li symmetric battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0105] This comparative example also provides a lithium iron phosphate metal secondary battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0106] Comparative Example 4

[0107] This comparative example provides a three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0108] 101.219 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin and 87.989 mg (0.1 mmol) of 4,4',4”,4””,4””-(9,10-dihydro-9,10-[1,2]benzanthracene-2,3,6,7,14,15-hexyl)hexabenzaldehyde were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 5 The difference is that this comparative example does not contain any metal M.

[0109] This comparative example also provides a composite negative electrode for metal secondary batteries. The difference from Example 1 is that the metal-doped three-dimensional covalent organic framework material used is the three-dimensional covalent organic framework material of this comparative example. Its preparation method is the same as that of Example 1, so it will not be described in detail.

[0110] This comparative example also provides a Li||Li symmetric battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0111] This comparative example also provides a lithium iron phosphate metal secondary battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0112] Comparative Example 5

[0113] This comparative example provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0114] 121.9365 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin cerium and 87.989 mg (0.1 mmol) of 4,4',4”,4””,4””-(9,10-dihydro-9,10-[1,2]benzanthracene-2,3,6,7,14,15-hexyl)hexabenzaldehyde were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 5 In this comparative example, metal M is cerium.

[0115] This comparative example also provides a composite negative electrode for metal secondary batteries. The difference from Example 1 is that the metal-doped three-dimensional covalent organic framework material used is the metal-doped three-dimensional covalent organic framework material of this comparative example. Its preparation method is the same as that of Example 1, so it will not be described in detail.

[0116] This comparative example also provides a Li||Li symmetric battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0117] This comparative example also provides a lithium iron phosphate metal secondary battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0118] Comparative Example 6

[0119] This comparative example provides a metal-doped three-dimensional covalent organic framework material, the preparation method of which includes the following steps:

[0120] 129.752 mg (0.15 mmol) of 5,10,15,20-tetra(4-aminophenyl)porphyrin iridium and 87.989 mg (0.1 mmol) of 4,4',4”,4””,4””-(9,10-dihydro-9,10-[1,2]benzanthracene-2,3,6,7,14,15-hexyl)hexabenzaldehyde were weighed and mixed in 4 mL of n-butanol. Then, 0.4 mL of 6 mol / L glacial acetic acid was added dropwise. The mixture was sonicated for 10 min, degassed under vacuum, and heated at 120 °C for 72 h to carry out Schiff base polymerization. After the reaction was completed, the mixture was filtered, and the filter residue was washed with acetone and tetrahydrofuran, followed by vacuum drying to obtain a metal-doped three-dimensional covalent organic framework material. The basic structure of the material can be found in [reference needed]. Figure 5 In this comparative example, the metal M is iridium.

[0121] This comparative example also provides a composite negative electrode for metal secondary batteries. The difference from Example 1 is that the metal-doped three-dimensional covalent organic framework material used is the metal-doped three-dimensional covalent organic framework material of this comparative example. Its preparation method is the same as that of Example 1, so it will not be described in detail.

[0122] This comparative example also provides a Li||Li symmetric battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0123] This comparative example also provides a lithium iron phosphate metal secondary battery. The difference from Example 1 is that the composite negative electrode for the metal secondary battery is the composite negative electrode prepared in this comparative example. Its preparation method is the same as that in Example 1, so it will not be described in detail.

[0124] The Li||Li symmetric batteries of Examples 1-4 and Comparative Examples 1-6 were tested for electrochemical performance on the Xinwei testing system under the conditions of 1 mA / cm2 and 1 mAh / cm2. The test results are shown in Table 1 below.

[0125] Table 1

[0126]

[0127]

[0128] Table 1 shows that the Li||Li symmetric cells assembled in the embodiments of the present invention have lower nucleation overpotential, polarization voltage, and longer cycle life compared with the Li||Li symmetric cells assembled in the comparative example.

[0129] The lithium iron phosphate metal secondary batteries of Examples 1-4 and Comparative Examples 1-6 were subjected to electrochemical performance tests on the Xinwei testing system. The test voltage range was 2.4-4.2V. The test results are shown in Table 2 below:

[0130] Table 2

[0131]

[0132] Table 2 shows that the lithium iron phosphate metal secondary batteries prepared using the method of this invention achieve significant improvements in both initial discharge capacity and cycle retention compared to batteries assembled using conventional methods. This result confirms the effectiveness of this invention in improving battery performance.

[0133] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A metal-doped three-dimensional covalent organic framework material, characterized in that, The metal-doped three-dimensional covalent organic framework material is formed by linking a 9,10-dihydro-9,10-[1,2]benzanthracene framework and a metal-doped β-tetraroxyporphyrin framework via nitrogen atoms. The 9,10-dihydro-9,10-[1,2]benzanthracene framework includes two first-dimensional linking sites, two second-dimensional linking sites, and two third-dimensional linking sites. For any 9,10-dihydro-9,10-[1,2]benzanthracene framework, at least one first-dimensional linking site is connected to the nitrogen atom via a double bond, at least one second-dimensional linking site is connected to the nitrogen atom via a double bond, and at least one third-dimensional linking site is connected to the nitrogen atom via a double bond. The four R groups of the metal-doped β-tetraroxyporphyrin framework are each connected to one nitrogen atom via a single bond. The metal includes one of cerium, iridium, platinum, and gold. The structural formula of the metal-doped three-dimensional covalent organic framework material is: M is one of cerium, iridium, platinum, or gold.

2. A method for preparing a metal-doped three-dimensional covalent organic framework material according to claim 1, characterized in that, The process includes the following steps: mixing metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin with a three-dimensional ketone compound, glacial acetic acid solution and a first solvent, degassing, reacting at 100-150℃ for 72-120 h, filtering, washing and drying to obtain the metal-doped three-dimensional covalent organic framework material. The metal is one of cerium, iridium, platinum, and gold; the three-dimensional ketone compound is formed by the 9,10-dihydro-9,10-[1,2]benzanthracene skeleton and at least three oxygen atoms connected by double bonds, wherein at least one first-dimensional linking site is connected to the oxygen atom, at least one second-dimensional linking site is connected to the oxygen atom, and at least one third-dimensional linking site is connected to the oxygen atom; the first solvent includes one or more of methanol, pyridine, N-methylpyrrolidone, o-dichlorobenzene, n-butanol, mesitylene, and 1,4-dioxane.

3. The method for preparing metal-doped three-dimensional covalent organic framework materials according to claim 2, characterized in that, The three-dimensional ketone compound is 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone.

4. The method for preparing a metal-doped three-dimensional covalent organic framework material according to claim 2, characterized in that, The molar ratio of the ketone carbonyl group in the three-dimensional ketone compound to the amino group in the metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin is 1:(1~1.2).

5. The method for preparing a metal-doped three-dimensional covalent organic framework material according to claim 2, characterized in that, The sum of the masses of the three-dimensional ketone compound and the metal-doped 5,10,15,20-tetra(4-aminophenyl)porphyrin: the volume of the first solvent = 20 mg: (1~2) ml, the volume ratio of the first solvent to the glacial acetic acid solution is 1: (0.1~0.2), and the concentration of the glacial acetic acid solution is 6-12 mol / L.

6. A negative electrode, characterized in that, It includes an active metal and the metal-doped three-dimensional covalent organic framework material of claim 1, wherein the active metal includes one or more of lithium, sodium, potassium, and zinc.

7. The negative electrode according to claim 6, characterized in that, The method for preparing the negative electrode includes the following steps: uniformly dispersing the metal-doped three-dimensional covalent organic framework material in a second solvent to obtain a mixed solution; uniformly drop-coating the mixed solution onto the surface of the active metal; heating the active metal until the second solvent on the surface of the active metal completely evaporates to obtain the negative electrode. The mass of the metal-doped three-dimensional covalent organic framework material: the volume of the second solvent = 1 mg : (1-3) mL; The amount of the mixed solution dropped onto the active metal surface is 0.17-0.28 μL / mm. 2 .

8. The negative electrode according to claim 7, characterized in that, The method for preparing the negative electrode further includes the following steps: heating the active metal at a temperature of 40-80°C for a time of 4-12 hours.

9. A secondary battery, characterized in that, The battery includes a battery casing and a negative electrode, a lithium iron phosphate positive electrode, a separator, and an electrolyte as described in any one of claims 6 to 8, located within the battery casing, wherein the separator is located between the positive electrode and the negative electrode.

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