Preparation method of sulfur-based composite material with self-repairing functional layer coating

Abstract

This invention provides a method for preparing a sulfur-based composite material with a self-healing functional layer coating, and this method significantly improves the electrochemical performance of the sulfur-based composite material. The method includes: dispersing an amino-structured compound containing polyethylene glycol (PEG) segments, an aldehyde-structured compound, and the sulfur-based composite material in a solvent in a certain proportion; and initiating a Schiff polymerization reaction of the aldehyde and amino groups by adding an appropriate amount of catalyst to generate a porous polymer containing imino groups, thereby forming an ultrathin, self-healing coating layer in situ on the surface of the sulfur-based composite material. This technology greatly alleviates the negative impact of the volume expansion and shuttle effect of the sulfur-based composite material on the battery, improving the battery's cycle performance and rate performance.

Description

Technical Field

[0001] This invention belongs to the field of chemical power sources, and in particular, a method for preparing a sulfur-based composite material with a self-healing functional layer coating. Background Technology

[0002] Covalent organic frameworks (COFs) are a class of long-range ordered porous crystalline polymers formed by covalent bonds of organic building blocks. They are primarily composed of non-metallic lightweight elements (such as C, N, O, and S) and possess advantages such as structural order, larger specific surface area, designable regular channels, and modifiability for functionalization. The design principles of COFs enable the creation of well-defined chemical structures, tunable pore sizes and geometries within the backbone. This allows for precise control over the positions of COF building blocks and diverse selection of functional groups in two-dimensional and three-dimensional space, while also yielding highly ordered crystalline network structures, thereby enabling targeted control over the physical and chemical properties of COFs. Constructing COFs with functionalized groups is of paramount importance, especially for lithium-ion battery applications.

[0003] Based on this, we innovatively utilize the ability to optimize ionic conductivity by guiding the growth of ordered structures through topological design combined with specific covalent bond polymerization between monomers. Porous imide polymer coating containing polyethylene glycol segments facilitates the self-healing of ultrathin functional layers, and the polyethylene glycol segment functionalized structure enables rapid lithium-ion transport. This method significantly improves the lithium-ion conductivity in cathode materials, enhances the ion diffusion capability of the material, and mitigates the effects of volume expansion and shuttle effects, providing a new solution for the development of high-performance batteries. Summary of the Invention

[0004] In a first aspect, a method for preparing a sulfur-based composite material with a self-healing functional layer includes the following steps:

[0005] S1: Take an appropriate proportion of halogenated oxygen-containing compounds and hydroxyl-structured compounds, disperse them in a solvent, and add an appropriate amount of catalyst to initiate a substitution reaction to generate a compound containing polyethylene glycol segments. Then add an ammonia compound to generate an amino-structured compound containing polyethylene glycol segments.

[0006] S2: Take an appropriate proportion of aldehyde-containing structural compound, amino-containing compound containing polyethylene glycol segments and sulfur-based composite material and disperse them in a solvent. At the same time, add an appropriate amount of initiator to initiate the Schiff polymerization of aldehyde and amino groups to form a porous imine polymer coating sulfur-based composite material containing polyethylene glycol segments.

[0007] S3: Sulfur-based composite materials include sulfur-based polymers and carbon-sulfur composite materials;

[0008] S4: Use the above-mentioned porous imide-coated sulfur-based composite material containing polyethylene glycol segments as the positive electrode material to equip the battery.

[0009] Preferably, in step S1, the halogenated oxygen-containing compound is an oxygen-containing halogenated hydrocarbon: 2-methoxyethoxymethyl chloride, 1-bromo-2-(2-methoxyethoxy)ethane, 1-iodo-2-(2-methoxyethoxy)ethane; the hydroxyl-structured compound is: p-methylphenol, 2,4,6-tri-tert-butylphenol, diphenolpropane, p-hydroxybenzoic acid, ethyl 2,5-dihydroxyterephthalate, sodium 2,8-dihydroxynaphthalene-6-sulfonate; the solvent is water, NMP, DMF; the catalyst is: potassium carbonate, potassium hydroxide, sodium hydroxide; the initiator is hydrochloric acid and acetic acid; and the ammonia compound is ammonia water, hydrazine, ammonia methanol, and ammonium chloride.

[0010] Preferably, the aldehyde-containing compound in step S2 is such as Figure 2 As shown, the molar ratio of aldehyde-containing compounds to amino-containing compounds with polyethylene glycol segments is 1:100-100:1; the mass ratio of polyethylene glycol segment porous imine compounds to sulfur-containing compounds in the cathode material is 1:100-100:1.

[0011] Preferably, in step S3, the sulfur-based polymer material is sulfurized polyacrylonitrile, sulfurized polyacrylic acid, phenyl polysulfide, sulfurized polytetravinylpyridine, diallyl polysulfide, sulfurized aminophenolic resin, or sulfurized poly(1,2,4,5-4 amino)benzene; the carbon-sulfur composite material is porous carbon / sulfur, hollow carbon / sulfur, graphene and its derivatives / sulfur, carbon nanotubes and their derivatives / sulfur, or carbon nanofibers / sulfur.

[0012] In a second aspect, a self-healing functional layer coated sulfur composite cathode material is characterized by being prepared by the preparation method described in any one of claims 1 to 3.

[0013] Thirdly, the method for in-situ improving the cycle life of sulfur-based compound cathode materials as described in the second aspect is characterized in that it is applied to lithium metal batteries, lithium-ion batteries, sodium-ion batteries, sodium metal batteries, potassium-ion batteries, or potassium metal batteries.

[0014] Compared to existing technologies, the significant advantages of this invention are as follows:

[0015] (1) High-efficiency ion transport: The lithium-ion transport efficiency is improved by introducing a functionalized polyethylene glycol (PEG) segment structure. In this design, the oxygen atoms in the PEG segments can provide a fast lithium-ion transfer channel, thereby improving the rate performance of the battery.

[0016] (2) Mitigating the effects of volume expansion: Since the coating layer has a self-healing function, the coating layer fracture caused by volume expansion during charging and discharging can be repaired by itself, which helps to mitigate the effects of volume expansion. This characteristic plays an important role in improving the stability and cycle life of the battery.

[0017] (3) Economic sustainability: The self-healing functional layer-coated sulfur-based composite material prepared using this innovative method not only exhibits excellent economic efficiency and high performance, but also perfectly aligns with the environmental protection concept of green production. In addition, it significantly reduces the difficulty of large-scale production, paving a solid path for the battery industry towards a sustainable future. Attached Figure Description

[0018] Figure 1 This is the battery's rate data.

[0019] Figure 2 This is a schematic diagram of a compound containing a hydroxyl group.

[0020] Figure 3 This is a schematic diagram of the structure of a compound containing an aldehyde group.

[0021] Figure 4 This is a schematic diagram of the structure of PEG-NHNH2.

[0022] Figure 5 This is a schematic diagram of the structure of a polyethylene glycol segmental porous imine polymer.

[0023] Figure 6 Electron micrographs of the coating material Detailed Implementation

[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred experimental examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Implementation Case 1

[0028] 0.25 mol of 1-bromo-2-(2-methoxyethoxy)ethane, 0.1 mol of diethyl 2,5-dihydroxyterephthalate, and 0.045 mol of potassium carbonate were dissolved in 500 mL of anhydrous acetonitrile, resulting in a substitution reaction that introduces oxygen into the benzene ring, generating PEG-CH2CH3. 0.45 mol of PEG-CH2CH3 was dissolved in 400 mL of ethanol and 50 mL of hydrazine hydrate to give the final product PEG-NHNH2. Figure 4 As shown. 0.05 mol of 1,4-dicarboxybenzene and 0.15 mol of PEGNHNH2 were added to water, followed by the dispersion of 30 g of graphene and its derivatives / sulfur. 0.01 g of acetic acid was added as an initiator to promote the polymerization reaction between the aldehyde and amino groups, generating a polyethylene glycol segmental porous polymer, such as... Figure 4 As shown, and in situ coated onto the carbon-sulfur composite material, as Figure 5 As shown, the porous imine polymer-coated carbon-sulfur composite material prepared above was used as the positive electrode material. We used this material as the positive electrode and lithium metal as the negative electrode to assemble a Li-S battery pouch, as shown... Figure 6 As shown, a rate charge-discharge test was conducted, and the discharge specific capacity of the material at a 1C rate was 849 mAh / g.

[0029] Implementation Case 2

[0030] 0.4 mol of 1-(2-chloroethoxy)-2-(2-methoxyethoxy)ethane, 0.3 mol of 2,5-dihydroxy-1,4-phenylenediacetic acid, and 0.06 mol of sodium hydroxide were dissolved in 600 mL of NMP, resulting in a substitution reaction that introduced oxygen into the benzene ring, generating PEG-CH3. 0.45 mol of PEG-CH2CH3 was dissolved in 400 mL of ethanol and 50 mL of ammonium chloride to obtain the final product PEG-NHNH2. 0.15 mol of acetylphenylacetic acid and 0.3 mol of PEG-NH2 were added to the NMP organic solvent, followed by the dispersion of 10 g of vulcanized polyacrylic acid. 0.05 mol of acetic acid was added as an initiator to promote the polymerization reaction between the aldehyde and amino groups, generating a polyethylene glycol segment porous imine polymer, which was then in situ coated onto the vulcanized polyacrylic acid cathode material. The prepared porous imine-coated vulcanized polyacrylic acid material was used as the cathode material. We used this material as the positive electrode and lithium metal as the negative electrode to assemble a Li-S battery pouch. At a current density of 0.5C, the Li-S battery can cycle 150 times and remain stable. As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a sulfur-based composite material with a self-healing functional layer, comprising the following steps: S1: Take an appropriate proportion of halogenated oxygen-containing compounds and hydroxyl-structured compounds, disperse them in a solvent, and add an appropriate amount of catalyst to initiate a substitution reaction to generate a compound containing polyethylene glycol segments. Then add an ammonia compound to generate an amino-structured compound containing polyethylene glycol segments. S2: Take an appropriate proportion of aldehyde-containing structural compound, amino-containing compound containing polyethylene glycol segments and sulfur-based composite material and disperse them in a solvent. At the same time, add an appropriate amount of initiator to initiate the Schiff polymerization of aldehyde and amino groups to form a porous imine polymer coating sulfur-based composite material containing polyethylene glycol segments. S3: Sulfur-based composite materials include sulfur-based polymers and carbon-sulfur composite materials; S4: Use the above-mentioned porous imide-coated sulfur-based composite material containing polyethylene glycol segments as the positive electrode material to equip the battery.

2. The method for preparing a sulfur-based composite material with a self-healing functional layer according to claim 1, characterized in that, In step S1, the halogenated oxygen-containing compounds are oxygen-containing halogenated hydrocarbons: 2-methoxyethoxymethyl chloride, 1-bromo-2-(2-methoxyethoxy)ethane, and 1-iodo-2-(2-methoxyethoxy)ethane; the hydroxyl-structured compounds are: p-methylphenol, 2,4,6-tri-tert-butylphenol, diphenolpropane, p-hydroxybenzoic acid, ethyl 2,5-dihydroxyterephthalate, and sodium 2,8-dihydroxynaphthalene-6-sulfonate; the solvents are water, NMP, and DMF; the catalysts are: potassium carbonate, potassium hydroxide, and sodium hydroxide; the initiators are hydrochloric acid and acetic acid; and the ammonia compounds are ammonia water, hydrazine, ammonia methanol, and ammonium chloride.

3. The method for preparing a sulfur-based composite material with a self-healing functional layer according to claim 1, wherein the aldehyde-containing compound in step S2 is: p-isopropylbenzaldehyde, 2,4,6-trimethylbenzaldehyde, terphenyldicarboxaldehyde, 4-formylphenylboronic acid, benzaldehyde, tris(4-formylphenyl)amine, p-phenylenedialdehyde, 4,6-dihydroxybenzaldehyde, 1,3,5-tris(p-formylphenyl)benzene, biphenyldicarboxaldehyde, 2-hydroxy-1-naphthaldehyde; the molar ratio of the aldehyde-containing compound to the amino compound containing polyethylene glycol segments is 1:100-100:1; the mass ratio of the porous imine compound containing polyethylene glycol segments to the sulfur-containing compound as the cathode material is 1:100-100:

1.

4. The method for preparing a sulfur-based composite material with a self-healing functional layer according to claim 1, wherein the sulfur-based polymer material in step S3 is sulfurized polyacrylonitrile, sulfurized polyacrylic acid, phenyl polysulfide, sulfurized polytetravinylpyridine, diallyl sulfide, sulfurized aminophenolic resin, or sulfurized poly(1,2,4,5-4-amino)benzene; and the carbon-sulfur composite material is porous carbon / sulfur, hollow carbon / sulfur, graphene and its derivatives / sulfur, carbon nanotubes and their derivatives / sulfur, or carbon nanofibers / sulfur.

5. A self-healing functional layer-coated sulfur-based composite material, characterized in that... It is prepared by the method of preparing a sulfur-based composite material with a self-healing functional layer as described in any one of claims 1 to 4.

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