Silane modified zinc negative electrode material grafted with covalent organic framework protective coating as well as preparation method and application of silane modified zinc negative electrode material

Abstract

The invention provides a silane modified zinc negative electrode material grafted with a covalent organic framework protective coating as well as a preparation method and application of the silane modified zinc negative electrode material. The preparation method comprises the following steps: adding a zinc foil into a pretreatment solution of an ethanol-water mixed solution in which an alkyl chain extender is dissolved, reacting, adding a silane coupling agent, continuously reacting, washing and drying to obtain a silane modified zinc negative electrode; and adding the silane-modified zinc negative electrode into a reaction solution in which an aldehyde monomer and an amine monomer are dissolved for reaction, and performing washing, Soxhlet extraction and drying to obtain the silane-modified zinc negative electrode material grafted with the covalent organic framework protective coating. The silane modified zinc negative electrode material disclosed by the invention is strong in interface bonding force, high in ion transmission efficiency, excellent in dendritic crystal inhibition effect, simple and controllable in process, easily available in raw materials and suitable for large-scale production; and when the material is applied to the aqueous zinc ion battery, the material has excellent cycling stability and electrochemical performance, and a key material support is provided for industrialization of the high-performance aqueous zinc ion battery.

Description

Technical Field

[0001] This disclosure relates to the field of zinc-ion battery anode preparation technology, and in particular to a silane-modified zinc anode material with a grafted covalent organic framework protective coating, its preparation method, and its application. Background Technology

[0002] Aqueous zinc-ion batteries, employing water-soluble electrolytes (such as ZnSO4 aqueous solution), offer advantages such as low cost (inexpensive electrolyte raw materials), environmental friendliness (no risk of organic electrolyte pollution), and high safety (no risk of combustion or explosion), making them ideal candidate battery systems for large-scale energy storage and portable electronic devices. Among these, metallic zinc anodes are the preferred anode material for aqueous zinc-ion batteries due to their high theoretical capacity (820 mAh / g), low electrode potential (-0.76 V vs. standard hydrogen electrode), and abundant resources on Earth (zinc abundance in the Earth's crust is approximately 70 mg / kg). However, zinc anodes face three major problems in practical applications, severely restricting battery performance and lifespan: 1. Zinc dendrite growth: When zinc ions are deposited on the anode surface, irregular dendrites easily form due to uneven surface electric field distribution; during dendrite growth, they can easily pierce the separator, leading to internal short circuits and safety risks. Simultaneously, dendrite shedding causes loss of active material, reducing battery capacity; 2. Violent side reactions: When zinc anodes come into direct contact with aqueous electrolytes, hydrogen evolution reaction (2H₂O + 2e⁻) easily occurs. - → H2↑ + 2OH - The side reactions, including surface corrosion, generate a loose ZnO / Zn(OH)2 passivation layer. These side reactions not only cause fluctuations in electrolyte pH and loss of active materials, but also reduce the battery's coulombic efficiency (the coulombic efficiency of traditional zinc anode batteries is often below 85%). Furthermore, there is the problem of poor interface stability: traditional zinc anodes lack an effective protective layer on their surface, making the electrode-electrolyte interface prone to structural damage during charging and discharging, leading to increased polarization and decreased battery rate performance and cycle stability.

[0003] To address these issues, researchers have developed various modification strategies, including electrode surface coating, electrolyte additive introduction, and membrane modification. Among these, covalent organic frameworks (COFs) have become ideal substrates for zinc anode protective coatings due to their highly ordered porous structure (pore size adjustable from 1 to 5 nm), excellent chemical stability (resistance to acids and alkalis, and resistance to aqueous electrolyte corrosion), and unobstructed ion transport channels. However, current COF materials as metal protective coatings have drawbacks: the bonding force between the COF framework and the zinc anode surface is weak (relying solely on physical adsorption), making them prone to detachment during charging and discharging.

[0004] Therefore, developing a method to graft a covalent organic framework protective coating onto the surface of zinc anode material through strong covalent bonds is of great significance for the development of aqueous zinc-ion batteries. This method can fundamentally solve the problem of incompatibility at the organic-inorganic composite interface and effectively address issues such as dendrite formation, side reactions, and interface stability in zinc anodes. Summary of the Invention

[0005] This disclosure provides a silane-modified zinc anode material with a grafted covalent organic framework (COF) protective coating, its preparation method, and its application, in order to at least solve the above-mentioned technical problems existing in the prior art.

[0006] According to a first aspect of this disclosure, a method for preparing a silane-modified zinc anode material with a grafted covalent organic framework (COF) protective coating is provided, comprising the following steps: S1. Add zinc foil to a pretreatment solution containing an ethanol-water mixture of alkyl chain extenders. After the reaction, add silane coupling agent and continue the reaction. After washing and drying, obtain silane-modified zinc foil substrate. S2. The silane-modified zinc foil substrate is added to a reaction solution containing aldehyde monomers and amine monomers, and reacted at 25℃~180℃ for 12~120 hours. After washing, Soxhlet extraction and drying, a silane-modified zinc anode material with a grafted covalent organic framework protective coating is obtained.

[0007] In one embodiment, in step S1, the zinc foil is a polished zinc foil that has been ground and ultrasonically cleaned, the purpose of which is to remove the oxide layer and oil stains on the surface of the zinc foil.

[0008] In one embodiment, in step S1, the mass ratio of the alkyl chain extender to the zinc foil is 1:0.01 to 1:100, preferably 1:10, which can be adjusted according to the required thickness and mechanical strength of the interface layer; the mass ratio of the alkyl chain extender to the silane coupling agent is 1:0.001 to 1:10, preferably 1:0.5, which can be adjusted according to the required amount of COF grafting.

[0009] In one embodiment, the alkyl chain extender is at least one of tetraethyl silicate and tetrabutyl titanate.

[0010] In a preferred embodiment, the alkyl chain extender is tetraethyl silicate.

[0011] In one embodiment, the silane coupling agent is at least one of silanes containing functional groups of amino, epoxy, vinyl, and mercapto groups.

[0012] In a preferred embodiment, the silane coupling agent is 3-aminopropyltriethoxysilane or 3-glycidyl etheroxypropyltrimethoxysilane.

[0013] In one embodiment, in step S1, the reaction is carried out at 25~35°C for 1~2 hours, and the reaction is continued for 4~6 hours.

[0014] In a preferred embodiment, in step S1, the reaction is carried out at 30°C for 1 hour, and the reaction is continued for 5 hours.

[0015] In a preferred embodiment, in step S1, the washing is performed using ethanol.

[0016] In a preferred embodiment, in step S2, the reaction is carried out at 100°C for 72 hours, which can be adjusted according to the crystallinity and degree of polymerization of the desired COFs protective coating.

[0017] In one embodiment, the reaction is carried out under acetic acid catalytic conditions.

[0018] In a preferred embodiment, the concentration of the acetic acid is 6M.

[0019] In one embodiment, in step S2, the molar ratio of the aldehyde monomer to the amine monomer is 1:0.1 to 1:10, preferably 1:1.5, and can be adjusted according to the monomer functionality and the required pore size of the covalent organic framework protective coating.

[0020] In one embodiment, the aldehyde monomer is 1,3,5-tricarboxymethyl phloroglucinol or 1,3,5-trialdehydebenzene, and the amine monomer is 2,5-diaminobenzenesulfonic acid or p-phenylenediamine.

[0021] In a preferred embodiment, the aldehyde monomer is 1,3,5-tricarboxymethyl phloroglucinol, and the amine monomer is 2,5-diaminobenzenesulfonic acid.

[0022] In one embodiment, in step S2, the solvent of the reaction solution is a mixed solvent of 1,4-dioxane and mesitylene or dimethyl sulfoxide; wherein the volume ratio of 1,4-dioxane and mesitylene is 1:1.

[0023] In one embodiment, in step S2, the washing is repeated with ethanol and N,N-dimethylformamide to remove unreacted aldehyde and amine monomers.

[0024] In one embodiment, in step S2, the Soxhlet extraction is performed by Soxhlet extraction with methanol and tetrahydrofuran for 12 to 48 hours respectively.

[0025] In a preferred embodiment, in step S2, the Soxhlet extraction is performed by Soxhlet extraction with methanol and tetrahydrofuran for 24 hours respectively.

[0026] In one embodiment, in step S2, the drying is performed under vacuum at 50-70°C for 8-16 hours.

[0027] In a preferred embodiment, in step S2, the drying is performed by vacuum drying at 60°C for 12 hours.

[0028] According to a second aspect of this disclosure, a silane-modified zinc anode material with a grafted covalent organic framework protective coating prepared by the above preparation method is provided.

[0029] In this disclosure, the material achieves covalent bonding (grafting) between the COFs protective coating and the zinc foil substrate through Zn-O-Si covalent bonds (zinc foil substrate and silane coupling agent) and Si-R-COFs covalent bonds (silane coupling agent and COFs monomers), thus forming an integrated composite structure.

[0030] According to a third aspect of this disclosure, the application of the aforementioned zinc anode material in improving battery performance is provided.

[0031] In one possible embodiment, the battery is an aqueous zinc-ion battery, specifically an aqueous zinc-ion button cell, such as a CR2032 type button cell.

[0032] In one possible implementation, the performance includes nucleation overpotential, cycle lifetime, hydrogen evolution volume, specific capacity, coulombic efficiency, capacity retention, open-circuit voltage, and high and low temperature performance.

[0033] According to a fourth aspect of this disclosure, an aqueous zinc-ion battery is provided, which is assembled using the aforementioned zinc negative electrode material as the negative electrode material, manganese dioxide (MnO2), vanadium pentoxide or Prussian blue analogues as positive electrode materials, an aqueous solution of zinc sulfate and manganese sulfate as the electrolyte, and glass fiber as the separator.

[0034] In one embodiment, the positive electrode material further includes a conductive agent and a binder.

[0035] In a preferred embodiment, the conductive agent is acetylene black and the binder is polyvinylidene fluoride (PVDF).

[0036] In one embodiment, the positive electrode material is a stainless steel foil coated with N-methylpyrrolidone (NMP) after being mixed with MnO2 powder, acetylene black and PVDF in a mass ratio of 7:2:1; the concentrations of zinc sulfate and manganese sulfate are 2 M and 0.1 M, respectively.

[0037] In one embodiment, the aqueous zinc-ion battery is an aqueous zinc-ion button cell, such as a CR2032 type button cell.

[0038] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved: This disclosure discloses a method for preparing silane-modified zinc anode materials with grafted covalent organic framework protective coatings. A silane coupling agent with an amphiphilic structure is introduced as an interface modifier between COFs and a zinc foil substrate, achieving a stable and strong covalent interface bond between "COFs-silane coupling agent-zinc foil substrate". Specifically, the silane coupling agent acts as an interface connecting layer (molecular bridge) to establish stable chemical bonds (Zn-O-Si and Si-R-COFs) between the zinc foil substrate and the COFs protective coating, enhancing the interfacial bonding force and preventing detachment, thus avoiding performance degradation due to interfacial failure during battery cycling. Simultaneously, the highly ordered nanoporous structure of the COFs acts as an "ion sieve," homogenizing the zinc ion flux at the interface, effectively suppressing zinc dendrite growth and improving ion transport efficiency. Furthermore, leveraging the organic hydrophobic properties of the silane coupling agent and the COFs framework, a hydrophobic barrier is constructed on the zinc surface, shielding active water molecules from direct contact with the zinc metal and effectively suppressing side reactions. In addition, the preparation process is simple, cost-controllable, and has good controllability and mass production feasibility, making it suitable for large-scale production and refined modification applications.

[0039] Therefore, the silane-modified zinc anode material with grafted covalent organic framework protective coating prepared in this disclosure exhibits excellent cycle stability and electrochemical performance when applied to aqueous zinc-ion batteries, providing key material support for the industrialization of high-performance aqueous zinc-ion batteries.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0041] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0042] Figure 1 A schematic diagram of the preparation process of the silane-modified zinc anode material grafted with a covalent organic framework protective coating disclosed in this invention is shown; wherein, 1 is the covalent organic framework protective coating, 2 is the alkyl coupling layer, and 3 is the zinc foil substrate; Figure 2 A schematic diagram of the synthetic route for grafting COFs onto a zinc anode using the monomer reaction of a silane coupling agent and COFs in Example 1 of this disclosure is shown. Figure 3A scanning electron microscope image of the surface of the silane-modified zinc anode material with a grafted covalent organic framework protective coating prepared in Example 1 of this disclosure is shown. Figure 4 The Fourier transform infrared spectrum of the silane-modified zinc anode material with a grafted covalent organic framework protective coating prepared according to Example 1 of this disclosure is shown. Figure 5 The X-ray diffraction pattern of the silane-modified zinc anode material with a grafted covalent organic framework protective coating prepared in Example 1 of this disclosure is shown. Figure 6 The diagram shows the cycle performance of a symmetric battery assembled using a silane-modified zinc anode material with a grafted covalent organic framework protective coating prepared in Example 1 of this disclosure under constant current charge-discharge conditions. Figure 7 The diagram illustrates the structure of an aqueous zinc-ion button cell provided in Application Example 1 of this disclosure; wherein, 1 is the positive electrode, 2 is the separator, 3 is the covalent organic framework protective coating, and 4 is the silane-modified zinc foil substrate. Detailed Implementation

[0043] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0044] The schematic diagram of the preparation process of the silane-modified zinc anode material with grafted covalent organic framework (COF) protective coating is shown in the figure below. Figure 1 As shown: First, zinc foil is modified using a silane coupling agent: the pretreated polished zinc foil is reacted with an alkyl chain extender and a silane coupling agent to graft an alkyl coupling layer 2 (an interface bonding layer formed by the silane coupling agent) onto the zinc foil surface, resulting in a silane-modified zinc foil substrate 3. Second, COFs are grafted onto the silane-modified zinc foil substrate using a monomer reaction between the silane coupling agent and COFs: the silane-modified zinc foil substrate is reacted with aldehyde monomers and amine monomers, and a covalent organic framework protective coating 1 is grafted onto the surface of the alkyl coupling layer 2, resulting in a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating 1. Here, 1 is the covalent organic framework protective coating, 2 is the alkyl coupling layer, and 3 is the zinc foil substrate. These three components are stably connected through covalent bonds Zn-O-Si and Si-R-COFs in the zinc foil substrate 3-alkyl coupling layer 2-covalent organic framework protective coating 1, forming an integrated composite structure. Detailed explanations are provided below with reference to specific embodiments.

[0045] Example 1 This embodiment describes the preparation of a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating; the specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. Synthesis route diagram as follows Figure 2 As shown, 1,3,5-triformylphloroglucinol and 2,5-diaminobenzenesulfonic acid were used as monomers for COFs. The reaction was carried out under 6M acetic acid catalysis at 100℃ for 72 hours to obtain a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating. This material achieves stable grafting of the COFs protective coating onto the zinc foil substrate through Zn-O-Si covalent bonds (zinc foil substrate and silane coupling agent) and Si-R-COFs covalent bonds (silane coupling agent and COFs monomers), forming an integrated composite structure. The specific steps are as follows: 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours. After that, it was taken out and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. It was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and vacuum dried at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-1) with a surface grafted covalent organic framework protective coating.

[0046] Example 2 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.05:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-2) with a surface-grafted covalent organic framework protective coating.

[0047] Example 3 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 100:1) and reacted at 30 °C for 1 hour. 75 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating (denoted as Zn@IM-COF-3).

[0048] Example 4 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 1.5 mg of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating (denoted as Zn@IM-COF-4).

[0049] Example 5 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 1.5 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-5) with a surface-grafted covalent organic framework protective coating.

[0050] Example 6 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of dimethyl sulfoxide as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating (denoted as Zn@IM-COF-6).

[0051] Example 7 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 25 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-7) with a surface-grafted covalent organic framework protective coating.

[0052] Example 8 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 180 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours each and vacuum dried at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-8) with a surface-grafted covalent organic framework protective coating.

[0053] Example 9 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 12 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-9) with a surface-grafted covalent organic framework protective coating.

[0054] Example 10 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 120 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-10) with a surface-grafted covalent organic framework protective coating (IM-COF-10).

[0055] Example 11 This embodiment describes the preparation of a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating; the specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (ethanol to water volume ratio 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (the mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30°C for 1 hour. Then, 0.075 g of 3-glycidyl etheroxypropyltrimethoxysilane was added, and the reaction continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours. After that, it was taken out and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. It was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and vacuum dried at 60 °C for 12 hours to obtain a silane-modified zinc anode material (denoted as Zn@IM-COF-11) with a surface grafted covalent organic framework protective coating.

[0056] Comparative Example 1 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-tricarboxymethyl phloroglucinol and p-phenylenediamine were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours each and vacuum dried at 60 °C for 12 hours to obtain a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating (denoted as Zn@IM-COF-12).

[0057] Comparative Example 2 This embodiment describes the preparation of a zinc anode material with a surface-grafted covalent organic framework protective coating. The specific process is as follows: 1. Modification of zinc foil using silane coupling agents For commercial zinc foil (5 cm) 5 cm The zinc foil (0.1 mm) was polished and ultrasonically cleaned to remove the surface oxide layer and oil stains, yielding 1.5 g of polished zinc foil. Tetraethyl silicate was dissolved in a mixture of 100 mL of ethanol and water (volume ratio of ethanol to water 8:1) as a pretreatment solution. The polished zinc foil was immersed in the pretreatment solution (mass ratio of tetraethyl silicate to polished zinc foil was 0.1:1) and reacted at 30 °C for 1 hour. 0.075 g of 3-aminopropyltriethoxysilane was added, and the reaction was continued for 5 hours. The foil was then removed, washed with ethanol, and dried. An alkyl coupling layer was grafted onto the surface of the polished zinc foil to obtain a silane-modified zinc foil substrate. 2. Grafting COFs onto the zinc anode using the monomer reaction of silane coupling agents and COFs. 1,3,5-trialdehydebenzene and 2,5-diaminobenzenesulfonic acid were weighed at a molar ratio of 1:1.5 as monomers for COFs and dissolved in 20 mL of a mixed solvent of 1,4-dioxane and mesitylene (volume ratio of 1,4-dioxane and mesitylene 1:1) as the reaction solution. The silane-modified zinc foil substrate was vertically immersed in the reaction solution and reacted at 100 °C for 72 hours with 6M acetic acid as a catalyst. After that, the substrate was removed and repeatedly washed with ethanol and N,N-dimethylformamide to remove unreacted monomers. The substrate was then extracted with methanol and tetrahydrofuran for 24 hours, respectively, and dried under vacuum at 60 °C for 12 hours to obtain a silane-modified zinc anode material with a surface-grafted covalent organic framework protective coating (denoted as Zn@IM-COF-13).

[0058] Experimental Example 1 This experimental example tests the silane-modified zinc anode materials with surface-grafted covalent organic framework protective coatings obtained in Examples 1-11 and Comparative Examples 1 and 2. The specific process is as follows: I. Relevant structural characterization tests The silane-modified zinc anode material prepared in Example 1 was subjected to scanning electron microscopy (SEM), and the obtained SEM images are shown below. Figure 3 As shown, the results indicate that the zinc foil surface is covered with a dense and uniform film, and no obvious cracks or holes were observed, indicating that the covalent organic framework protective coating is tightly bonded to the zinc foil substrate. Fourier transform infrared spectroscopy (FTIR) was performed on the silane-modified zinc anode material prepared in Example 1. The obtained FTIR spectrum is shown below. Figure 4 As shown, the results are displayed at 1400~1550 cm. -1 and 700~850 cm -1 The vibrational absorption peaks appearing in the region indicate the presence of the benzene ring structure in IM-COF-1 within the prepared silane-modified zinc anode material; the peaks appearing in the 1500–1650 cm⁻¹ region suggest the presence of the benzene ring structure in IM-COF-1. -1 The presence of a CN stretching vibration absorption peak indicates the presence of imine linkage units in IM-COF-1 in the prepared silane-modified zinc anode material, demonstrating that the chemical structure of the prepared surface-grafted IM-COF-1 zinc anode material is consistent with theoretical expectations.

[0059] X-ray diffraction (XRD) was performed on the silane-modified zinc anode material prepared in Example 1, and the obtained XRD pattern is shown below. Figure 5 As shown, the results indicate that characteristic diffraction peaks belonging to IM-COF-1 appeared in the small-angle region (around ~4.9°), indicating that well-crystallized COFs materials were successfully synthesized on the zinc surface; a distinct characteristic peak curve in the 25°~30° range corresponds to the interlayer spacing of this two-dimensional COFs.

[0060] The silane-modified zinc anode material prepared in Example 1 was assembled into a Zn / / Zn symmetric battery. Its cycle performance under constant current charge-discharge conditions is shown in the figure below. Figure 6 As shown, the results indicate that the polarization voltage of the symmetrical battery is stable at 0.05 V, and it can cycle stably for more than 1000 hours without any short circuits or abnormal voltage fluctuations. This demonstrates that the silane-modified zinc anode material with a grafted covalent organic framework protective coating can greatly improve the cycle stability of the battery.

[0061] II. Relevant Performance Tests The relevant properties of the silane-modified zinc anode materials provided in the examples were tested, and the results are shown in Table 1. The reaction yields of the silane-modified zinc anode materials obtained in Examples 1-10 were between 67% and 98%, and the grafting rates were between 50% and 96%, demonstrating the strong covalent bonding ability of "COFs-silane coupling agent-zinc anode". The specific surface area of ​​67-1027 m² / g provides sufficient channels for zinc ion transport, and the hydrophilic angle of 18°-101° can construct a hydrophobic barrier as needed. The nucleation overpotential of 26-288 mV and the cycle life of 283-1020 hours indicate the significant effect of the preparation method disclosed in this paper on uniform zinc ion deposition and dendrite suppression. The hydrogen evolution volume in all examples was below the detection limit, effectively blocking hydrogen evolution and corrosion side reactions. The synergistic effect of various performance characteristics solves the problems of weak interfacial bonding, uneven ion transport, dendrite growth, and severe side reactions in the zinc anode. For example, Example 1 showed a grafting rate of 95%, a cycle life of 1020 hours, and a hydrogen evolution volume of 0 mL, verifying the improvement of interfacial stability by covalent bonding. Meanwhile, the high specific surface area of ​​COFs (863 m² / g) ensures efficient ion transport, providing multi-faceted performance support for the large-scale application of the material. Specific testing methods are as follows: 1. Reaction yield After the reaction is complete, the reaction solution is filtered, collected, and centrifuged. The supernatant is then dried and weighed to obtain the mass of the unreacted raw material.

[0062] Reaction yield = (Total mass of monomers fed into COFs - Mass of unreacted feedstock) / Total mass of monomers fed into COFs 2. Grafting rate Grafting rate = (mass of silane-modified zinc anode material with surface-grafted covalent organic framework protective coating - mass of silane-modified zinc anode) / total mass of monomers added to each COFs in the reaction 3. Specific surface area The covalent organic framework protective coating in the silane-modified zinc anode material with surface grafted covalent organic framework protective coating was scraped off with a scraper and collected. 100 mg of the sample was loaded into a nitrogen adsorption instrument, and the nitrogen adsorption of the sample was tested in a liquid nitrogen atmosphere and automatically converted into specific surface area.

[0063] 4. Water-friendly corner The contact angle of water droplets on silane-modified zinc anode materials (i.e., the surface of the covalent organic framework protective coating) grafted with covalent organic framework protective coatings on different surfaces was measured using a contact angle meter. The larger the contact angle, the better the hydrophobicity and the stronger the corrosion resistance.

[0064] 5. Nucleation overpotential Assemble a Zn / / Zn symmetric cell and test the nucleation overpotential during zinc deposition. A lower overpotential indicates better interfacial zinc affinity, which is beneficial for uniform zinc deposition.

[0065] 6. Cycle life Assemble a Zn / / Zn symmetric cell at 1 mA cm⁻¹ -2 1 mAh cm -2 Under certain conditions, constant current charge and discharge tests were performed, and the time when the battery experienced a short circuit or abnormal voltage fluctuation was recorded.

[0066] 7. Hydrogen evolution volume Assemble a closed system of Zn / / Zn symmetric cells at 1 mA cm⁻¹ -2 1 mAh cm -2 Under constant current charge-discharge conditions, hydrogen gas evolved during the battery reaction was collected by water displacement method over 100 hours and its volume was measured.

[0067] Table 1. Evaluation results of silane-modified zinc anode materials in Examples 1-10 and Comparative Examples 1-2, and electrochemical performance test results of their symmetric cells.

[0068] Experimental Example 2 In this experimental example, the modified zinc anode materials prepared in each embodiment were cut into 12 mm diameter discs to serve as anodes, assembled into an aqueous zinc-ion coin cell (i.e., a CR2032 type coin cell), and the electrochemical performance of the cell was tested. A schematic diagram of the CR2032 type coin cell is shown below. Figure 7 As shown, 1 is the positive electrode (prepared by uniformly coating a stainless steel foil surface with a mixture of MnO2 powder, acetylene black, and PVDF in a mass ratio of 7:2:1, dispersed in N-methylpyrrolidone (NMP)), 2 is the separator (glass fiber), 3 is the covalent organic framework protective coating, and 4 is the silane-modified zinc foil substrate (silane-modified zinc negative electrode). The silane-modified zinc negative electrode material 4 with the surface-grafted covalent organic framework protective coating 3 prepared in each embodiment and comparative example serves as the negative electrode. The electrolyte fills the entire battery between the positive and negative electrodes. The specific preparation process and performance testing methods are as follows: I. Preparation of CR2032 coin cell 1. Application Example 1 The Zn@IM-COF-1 prepared in Example 1 was cut into 12 mm diameter discs to serve as the negative electrode; MnO2 powder, acetylene black and PVDF were mixed in a 7:2:1 mass ratio and dispersed in N-methylpyrrolidone (NMP) and coated on stainless steel foil to serve as the positive electrode; an aqueous zinc-ion coin cell (i.e., CR2032 type coin cell) was assembled using 2 M ZnSO4 + 0.1 M MnSO4 aqueous solution as the electrolyte and glass fiber as the separator.

[0069] 2. Application Example 2 The Zn@IM-COF-6 prepared in Example 6 was cut into 12 mm diameter discs to serve as the negative electrode; MnO2 powder, acetylene black and PVDF were mixed in a mass ratio of 7:2:1 and dispersed in N-methylpyrrolidone (NMP) and coated on stainless steel foil to serve as the positive electrode; an aqueous zinc-ion coin cell (i.e., CR2032 type coin cell) was assembled using 2 M ZnSO4 + 0.1 M MnSO4 aqueous solution as the electrolyte and glass fiber as the separator.

[0070] 3. Application Example 3 The Zn@IM-COF-8 prepared in Example 8 was cut into 12 mm diameter discs to serve as the negative electrode; MnO2 powder, acetylene black and PVDF were mixed in a mass ratio of 7:2:1 and dispersed in N-methylpyrrolidone (NMP) and coated on stainless steel foil to serve as the positive electrode; an aqueous zinc-ion coin cell (i.e., CR2032 type coin cell) was assembled using 2 M ZnSO4 + 0.1 M MnSO4 aqueous solution as the electrolyte and glass fiber as the separator.

[0071] 4. Application of Comparative Example 1 The Zn@IM-COF-12 prepared in Comparative Example 1 was cut into discs with a diameter of 12 mm and used as the negative electrode; MnO2 powder, acetylene black and PVDF were mixed in a mass ratio of 7:2:1 and dispersed in N-methylpyrrolidone (NMP) and coated on stainless steel foil as the positive electrode; an aqueous zinc-ion coin cell (i.e., CR2032 type coin cell) was assembled using 2 M ZnSO4 + 0.1 M MnSO4 aqueous solution as the electrolyte and glass fiber as the separator.

[0072] 5. Application of Comparative Example 2 The Zn@IM-COF-13 prepared in Comparative Example 2 was cut into discs with a diameter of 12 mm and used as the negative electrode; MnO2 powder, acetylene black and PVDF were mixed in a mass ratio of 7:2:1 and dispersed in N-methylpyrrolidone (NMP) and coated on stainless steel foil as the positive electrode; an aqueous zinc-ion coin cell (i.e., CR2032 type coin cell) was assembled using 2 M ZnSO4 + 0.1 M MnSO4 aqueous solution as the electrolyte and glass fiber as the separator.

[0073] II. Electrochemical Performance Testing of the Battery 1. Specific capacity: in 1 A g -1 The battery was subjected to charge-discharge cycle tests at high current density, and the discharge capacity of each cycle was recorded.

[0074] 2. Coulomb efficiency: at 2 Ag -1The battery was subjected to charge-discharge cycle tests at high current density, and the coulombic efficiency of each cycle was recorded, which is the ratio of the battery's discharge capacity to its charge capacity, reflecting the charge utilization efficiency.

[0075] 3. Capacity retention: at 5 A g -1 The battery was subjected to charge-discharge cycle tests at high current density, and the ratio (%) of the discharge capacity after 100 cycles to the initial discharge capacity was recorded to reflect the degree of battery capacity decay.

[0076] Excellent: Capacity retention ≥90%; Generally: 80% ≤ Capacity retention rate < 90%; Poor: Capacity retention ≤80%.

[0077] 4. Open circuit voltage: The electrode potential difference when the battery is unloaded, determined by the equilibrium potential of the positive and negative electrodes, reflects the initial electrochemical equilibrium state of the battery. Abnormal fluctuations in open circuit voltage may indicate electrolyte decomposition or electrode interface failure.

[0078] 5. Cycle life: The battery, under specified conditions, can achieve a cycle life of 1 A g. -1 The number of cycles at which the capacity decays to 80% of its initial value at a given current density (room temperature).

[0079] Excellent: Cycle life ≥ 800 cycles; Generally: 200 cycles ≤ cycle life < 500 cycles; Poor: Cycle life ≤200 cycles.

[0080] 6. High and low temperature performance: The battery's ability to maintain performance at extreme temperatures (-20 ℃ to 60 ℃), including low temperature capacity retention and high temperature cycle life.

[0081] The test results of the electrochemical performance of the batteries are shown in Table 2. The CR2032 coin cell full cells in Application Examples 1-3 have good electrochemical performance, especially the full cell performance shown in Application Example 1.

[0082] Table 2 Electrochemical performance test results of CR2032 coin cells in Application Examples 1-3 and Comparative Application Example 1-2

[0083] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0085] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for preparing a silane-modified zinc anode material with a grafted covalent organic framework protective coating, characterized in that, The preparation method includes the following steps: S1. Add zinc foil to a pretreatment solution containing an ethanol-water mixture of alkyl chain extenders. After the reaction, add silane coupling agent and continue the reaction. After washing and drying, obtain silane-modified zinc foil substrate. S2. The silane-modified zinc foil substrate is added to a reaction solution containing aldehyde monomers and amine monomers, and reacted at 25℃~180℃ for 12~120 hours. After washing, Soxhlet extraction and drying, a silane-modified zinc anode material with a grafted covalent organic framework protective coating is obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the alkyl chain extender to the zinc foil is 1:0.01 to 1:100; Preferably, the mass ratio of the alkyl chain extender to the silane coupling agent is 1:0.001 to 1:

10.

3. The preparation method according to claim 1, characterized in that, In step S1, the alkyl chain extender is at least one of tetraethyl silicate and tetrabutyl titanate; the silane coupling agent is at least one of silanes containing functional groups of amino, epoxy, vinyl and mercapto groups. Preferably, the silane coupling agent is 3-aminopropyltriethoxysilane or 3-glycidyl etheroxypropyltrimethoxysilane.

4. The preparation method according to claim 1, characterized in that, In step S1, the reaction is carried out at 25~35℃ for 1~2 hours, and the continued reaction is carried out for 4~6 hours.

5. The preparation method according to claim 1, characterized in that, In step S2, the molar ratio of the aldehyde monomer to the amine monomer is 1:0.1 to 1:10; Preferably, the aldehyde monomer is 1,3,5-tricarboxymethyl phloroglucinol or 1,3,5-trialdehydebenzene, and the amine monomer is 2,5-diaminobenzenesulfonic acid or p-phenylenediamine; More preferably, the aldehyde monomer is 1,3,5-tricarboxymethyl phloroglucinol, and the amine monomer is 2,5-diaminobenzenesulfonic acid.

6. The preparation method according to claim 1, characterized in that, In step S2, the solvent of the reaction solution is a mixed solvent of 1,4-dioxane and mesitylene or dimethyl sulfoxide; Preferably, the washing is repeated with ethanol and N,N-dimethylformamide; More preferably, the Soxhlet extraction is performed by Soxhlet extraction with methanol and tetrahydrofuran for 12 to 48 hours respectively; Most preferably, the drying is performed under vacuum at 50-70°C for 8-16 hours.

7. The preparation method according to claim 1, characterized in that, In step S1, the zinc foil is a polished zinc foil that has been ground and ultrasonically cleaned.

8. The silane-modified zinc anode material with a grafted covalent organic framework protective coating prepared by any of the preparation methods described in claims 1-7.

9. The application of the silane-modified zinc anode material according to claim 8 in improving battery performance.

10. An aqueous zinc-ion battery, characterized in that, The aqueous zinc-ion battery is assembled using the silane-modified zinc anode material as described in claim 8 as the anode material, manganese dioxide, vanadium pentoxide, or Prussian blue analogues as the cathode material, an aqueous solution of zinc sulfate and manganese sulfate as the electrolyte, and glass fiber as the separator.

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