Zinc negative electrode protection layer for regulating and controlling zinc ion transmission based on bimetal MOF channel, preparation method of zinc negative electrode protection layer, composite zinc negative electrode and aqueous zinc metal battery

Abstract

The invention belongs to the technical field of aqueous zinc metal batteries, and particularly relates to a zinc negative electrode protection layer for regulating and controlling zinc ion transmission based on a bimetal MOF channel, a preparation method of the zinc negative electrode protection layer, a composite zinc negative electrode and an aqueous zinc metal battery. Zirconium salt and zinc salt are mixed in a solvent environment, an organic ligand is added, a UiO-10 Zn material is synthesized through a solvothermal reaction, and then the surface of zinc foil is coated with the UiO-10 Zn material to form a protective layer. The transmission of Zn < 2 + > at an electrode-electrolyte interface can be effectively promoted, the migration ability of Zn < 2 + > is improved by Zr-Zn bimetal sites, and the uniform deposition of zinc is guided by three-dimensional ordered pore channels. When the prepared electrode total battery is matched with an NH4V4O10 positive electrode, the specific capacity is kept at 108.8 mAh g <-1 > after 200 cycles under the current density of 1 A g <-1 >.

Description

A zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport and its preparation method, composite zinc anode, and aqueous zinc metal battery Technical Field

[0001] This invention belongs to the field of aqueous zinc metal battery technology, specifically relating to a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport and its preparation method, a composite zinc anode, and an aqueous zinc metal battery. Background Technology

[0002] Aqueous zinc-metal batteries have become an ideal choice for large-scale energy storage systems due to their high safety, environmental friendliness, and low cost. However, zinc anodes suffer from problems such as dendrite growth and side reactions (hydrogen evolution, corrosion, and passivation), which severely limit battery cycle life. The root cause lies in the uneven deposition of zinc ions leading to local electric field distortion, the release of water molecules from the desolvation of hydrated zinc ions triggering hydrogen evolution reactions, and the passivation of electrodes caused by interfacial byproducts (such as basic zinc sulfate). Enhancing the stability of the zinc anode in electrochemical reactions is one of the important optimization directions for improving the overall performance of zinc-metal batteries.

[0003] Currently, artificial interface layers are widely used to regulate the stability of interfacial reactions during zinc ion deposition. This physically dense protective layer can isolate water molecules from direct contact with the electrode interface, significantly reducing the frequency of adverse side reactions such as corrosion, passivation, and hydrogen evolution at the interface. Various inorganic materials, including carbonaceous materials, metal alloys, metal salts, and inorganic non-metallic materials, as well as polymers and composite organic materials, have been used to construct functionalized artificial interface layers. While these layers generally achieve regulation of zinc ion flux and suppression of side reactions, they lack the ability to adjust pore size and modify channel structure, thus failing to achieve rapid zinc ion migration and complete suppression of side reactions. Summary of the Invention

[0004] The purpose of this invention is to develop a method for regulating Zn 2+ This paper presents a method for preparing a bimetallic MOF (UiO-66-10%Zn, or UiO-10Zn) protective layer to stabilize the deposition interface reaction. The method achieves Zn stability through bimetallic site modulation. 2+ By capturing and repelling anions, the Zr-Zn bimetallic sites reduce Zn content. 2+ Migration energy barrier, three-dimensional ordered channels (~6Å) guide Zn 2+ Uniform diffusion.

[0005] Therefore, the first aspect of the present invention provides a method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by a bimetallic MOF channel. The preparation method includes: Step 1. Uniformly mixing zirconium salt, zinc salt and a first organic solvent to obtain a first mixed solution; Step 2. Uniformly mixing the first mixed solution with an organic ligand to obtain a second mixed solution; Step 3. Transferring the second mixed solution to a reaction vessel for solvothermal reaction; Step 4. After the reaction, the product obtained is washed multiple times with a second organic solvent and deionized water, and dried to obtain bimetallic MOF powder; Step 5. Mixing the bimetallic MOF powder and polyvinylidene fluoride in a third organic solvent to form a slurry, coating the slurry onto the surface of a zinc foil, and drying it to serve as a zinc anode protective layer; In Step 1, the molar ratio of Zn to Zr is 5~40:100.

[0006] Metal-organic frameworks (MOFs), as materials with uniform porous structures, enable the rapid transport of zinc ions to the electrode surface within the pores, resulting in a uniformly quantified zinc ion flux and effectively avoiding electric field fluctuations and uneven ion concentration diffusion. Taking UiO-66 as a specific example, UiO-66 is a MOF material with Zr-O hexahedral units as its basic units. Zr clusters, acting as metal nodes, are connected to organic ligands to form an ordered three-dimensional porous structure, providing abundant channels for zinc ions to diffuse from the electrolyte interface to the electrode surface. The strong bonding ability of the Zr-O clusters ensures the long-term stability of the three-dimensional framework of UiO-66 in complex electrochemical environments. These metal sites can also provide additional Zn in certain situations. 2+ Adsorption sites. By adjusting the metal sites of UiO-66, the above technical solution can obtain a zinc anode MOF protective layer with rapid zinc ion transport and side reaction suppression capabilities.

[0007] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport through bimetallic MOF channels, the molar ratio of Zn to Zr in step 1 is 5~20:100. By optimizing the molar ratio of Zn to Zr, the pore structure and metal site configuration of the bimetallic MOF can be precisely controlled, thereby effectively promoting the rapid migration of Zn ions. This regulation helps to form a selective protective layer at the electrode-electrolyte interface, reducing dendrite growth and side reactions, thereby improving the cycle life and interface stability of the battery.

[0008] As a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, in step 1, the zirconium salt is selected from at least one of zirconium tetrachloride and zirconium nitrate; as a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, in step 1, the zinc salt is selected from at least one of zinc chloride, zinc nitrate, and zinc acetate; as a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, in step 2, the molar ratio of metal salt to organic ligand is 0.9~1.1:1, based on the total molar number of Zn ions and Zr ions. Precisely controlling the molar ratio of metal salt to organic ligand can ensure the crystallinity and pore structure uniformity of the MOF material. This optimization helps to improve the stability and ion transport performance of the MOF material, thereby further enhancing the protective effect of the zinc anode.

[0009] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport using bimetallic MOF channels, in step 2, the organic ligand is at least one of terephthalic acid, 2-amino-1,4-phthalic acid, and 2,5-dihydroxyterephthalic acid. Selecting different organic ligands can adjust the pore size and functional groups of the MOF, thereby affecting the transport performance and selectivity of Zn ions. The use of these organic ligands can improve the selective ion transport capability of the MOF material and further suppress dendrite growth and side reactions.

[0010] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport using bimetallic MOF channels, step 3 involves a reaction temperature of 100–150 °C and a reaction time of 12–48 h. Optimizing the temperature and time of the solvothermal reaction ensures sufficient crystallization of the MOF material and precise formation of the pore structure. This optimization helps improve the structural stability and ion transport performance of the MOF material, thereby enhancing the protective effect of the zinc anode.

[0011] As a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, step 1 involves uniform mixing by stirring at a rate of 400-500 rpm for 20-40 minutes. Appropriate stirring rate and time ensure uniform mixing of the reactants, avoiding excessively high or low local concentrations, thereby improving the uniformity and consistency of the MOF material.

[0012] As a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, step 2 involves uniform mixing by stirring at a rate of 400-500 rpm for 20-40 minutes; optionally, ultrasonic treatment is performed simultaneously with stirring. Ultrasonic treatment can further promote the uniform mixing and dispersion of reactants, reduce agglomeration, and improve the crystallinity and pore structure uniformity of the MOF material.

[0013] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport through bimetallic MOF channels, the drying method in steps 1 and 2 is vacuum drying. Vacuum drying can effectively remove solvents and moisture, avoid structural damage to the MOF material caused by high temperatures, and ensure the integrity and performance of the MOF material.

[0014] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport using bimetallic MOF channels, the liner of the reactor in step 3 is polytetrafluoroethylene (PTFE). PTFE liner possesses excellent chemical stability and corrosion resistance, preventing the introduction of impurities and corrosion of the reactor during the reaction process, thus ensuring the purity and performance of the MOF material.

[0015] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport using bimetallic MOF channels, step 1 includes N,N-dimethylformamide and optionally hydrochloric acid as the first organic solvent. N,N-dimethylformamide is a commonly used organic solvent that can effectively dissolve metal salts and organic ligands, promoting the formation of MOF materials. Optional hydrochloric acid can adjust the pH of the solution, further optimizing the crystallization and pore structure of the MOF material.

[0016] As a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, in step 4, the second organic solvent is N,N-dimethylformamide.

[0017] As a preferred embodiment, in the above-mentioned method for preparing a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels, the third organic solvent in step 5 is N-methylpyrrolidone.

[0018] As a preferred embodiment, in the above-described method for preparing a zinc anode protective layer based on the regulation of zinc ion transport via bimetallic MOF channels, the mass ratio of bimetallic MOF powder to polyvinylidene fluoride (PVDF) in step 5 is 8-10:1. Optimizing this mass ratio ensures the uniformity and adhesion of the coating, thereby improving the protective effect of the zinc anode. This optimization helps form a dense protective layer with ordered pores, reducing dendrite growth and side reactions, and improving the cycle life and interface stability of the battery.

[0019] A second aspect of the present invention provides a zinc anode protective layer, which is prepared by the above-described preparation method.

[0020] A third aspect of the present invention provides a composite zinc anode, the composite zinc anode comprising the aforementioned zinc anode protective layer. The thickness of the zinc anode protective layer is preferably 10-20 μm.

[0021] A fourth aspect of the present invention provides an aqueous zinc metal battery, the aqueous zinc metal battery comprising the above-described composite zinc negative electrode. More preferably, when the positive electrode is NH4V4O 10 The aqueous zinc metal battery at 1 A g -1 After 200 cycles at the current density, the specific capacity remained at 108.8 mAh g⁻¹. -1 .

[0022] The beneficial effects of this invention are: 1. By introducing a Zr-Zn bimetallic node, this invention significantly improves the Zn content at the electrode-electrolyte interface. 2+ Migration dynamics simultaneously enhance structural stability and charge transfer efficiency.

[0023] 2. The UiO-10 Zn protective layer prepared by this invention can enhance the Zn content. 2+ The ability to transport at the electrode-electrolyte interface, maintaining rapid charge transfer around the zinc cluster, Zn 2+ The migration number increased to 0.439 (0.288 for bare zinc).

[0024] 3. The UiO-10 Zn protective layer prepared in this invention can ensure the performance of the full cell (matching NH4V4O). 10 (Positive electrode) at 1 A g -1 After 200 cycles, the capacity is 108.8 mAh g. -1 .

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0026] Figure 1: XRD patterns of bimetallic MOF powders from different embodiments and Comparative Example 1; Figure 2: SEM images of bimetallic MOF powders from different embodiments and Comparative Example 1; Figure 3: SEM image of the product prepared in Comparative Example 2; Figure 4: Zinc ion transport number results of the zinc symmetric battery assembled in Example 2; Figure 5: SEM image of the zinc symmetric battery assembled in Example 2 after cycling; Figure 6: Cyclic stability curve of the zinc full cell assembled in Example 2. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the embodiments and comparative examples of this invention, the raw materials are commercially available.

[0029] Example 1 (Best Practice): A zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport and its preparation method, comprising the following steps: Step 1: Weigh 2.33 g zirconium tetrachloride and 0.136 g zinc chloride (Zn to Zr molar ratio of 10:100) and dissolve them in 60 mL DMF, stirring (450 rpm, 30 min) until the mixture dissolves to obtain mixed solution A; Step 2: Add 1.16 g terephthalic acid to mixed solution A, stir (450 rpm, 30 min) to dissolve and ultrasonically disperse for 20 min to obtain mixed solution B; Step 3: Transfer mixed solution B to a polytetrafluoroethylene-lined reactor and solvothermal reaction at 120 °C for 24 h; Step 4: After the reaction, the product obtained is washed multiple times with DMF and deionized water, and vacuum dried at 80 °C for 12 h to obtain bimetallic MOF powder; Step 5: Take 90 mg of bimetallic MOF powder and 10 mg of polyvinylidene fluoride (PVDF) in 500 μL The slurry was prepared in NMP and coated onto the surface of zinc foil. After vacuum drying at 80°C for 12 h, a bimetallic MOF@Zn composite electrode was obtained.

[0030] Example 2: Using the bimetallic MOF@Zn composite electrode prepared in Example 1 as the negative electrode material, zinc symmetric cells and full cells were prepared. The specific steps are as follows: 1. Weigh the bimetallic MOF powder and polyvinylidene fluoride (PVDF) prepared in Example 1, mix them evenly in a mass ratio of 9:1, and add N. 1. Methylpyrrolidone is stirred into a slurry; 2. The slurry prepared in step 1 is uniformly coated onto zinc foil using a scraper and dried in a vacuum drying oven at 80°C for 12 h; 3. The zinc foil obtained after drying in step 2 is sliced ​​using a punching machine to cut electrode sheets with a diameter of 14 mm; 4. The electrode sheet cut in step 3 is selected as the negative electrode, and NH4V4O coated on titanium foil with a diameter of 14 mm is used as the negative electrode. 10Using 2 M zinc sulfate as the positive electrode and Whatman glass fiber filter membrane as the separator, a CR 2032 battery case was selected; 5. A zinc symmetric battery was assembled in the following order: negative electrode case, bimetallic MOF@Zn composite electrode, separator, bimetallic MOF@Zn composite electrode, gasket, spring, and positive electrode case. An appropriate amount of electrolyte was added to assemble a button cell for electrochemical testing; 6. A coin cell was assembled in the following order: negative electrode case, bimetallic MOF@Zn composite electrode, separator, and NH4V4O 10 A zinc full cell was assembled in the order of positive electrode, gasket, spring, and positive electrode shell, and a coin cell was assembled by adding an appropriate amount of electrolyte for electrochemical testing.

[0031] Example 3: This example provides a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels and its preparation method. Except that the solution is adjusted to 50 mL DMF in step 1 and the organic ligand is the same molar amount of 2-amino-1,4-phenylenediic acid in step 2, the other process steps and process parameters are the same as in Example 1.

[0032] Example 4: This example provides a zinc anode protective layer based on the regulation of zinc ion transport by bimetallic MOF channels and its preparation method. Except that the solution in step 1 is adjusted to 50 mL DMF and 10 mL HCl, and the organic ligand in step 2 is the same as 2,5-dihydroxyterephthalic acid in the same molar amount, the other process steps and process parameters are the same as in Example 1.

[0033] Comparative Example 1: This example provides a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport and its preparation method. Except for the zinc chloride addition amount in step 1 being adjusted to 1.36 g (the molar ratio of Zn to Zr is 100:100), the other process steps and process parameters are the same as in Example 1.

[0034] Comparative Example 2: This example provides a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport and its preparation method. Except for the zinc chloride addition amount in step 1 being adjusted to 0.68 g (the molar ratio of Zn to Zr is 50:100), the other process steps and process parameters are the same as in Example 1.

[0035] Test Results: The products obtained in Examples 1, 3, and 4, as well as Comparative Example 1, were characterized by XRD. The results are shown in Figure 1. The final product synthesized using the same zirconium tetrachloride metal salt and benzoic acid series organic ligands was UiO-66. In Figure 1, the horizontal axis represents the diffraction angle in degrees; the vertical axis represents the intensity of the diffraction peak.

[0036] Figure 2 shows scanning electron microscope images of the products prepared in Examples 1, 3, 4 and Comparative Example 1. As shown in Figure 2, the bimetallic MOF powders prepared in Examples 1, 3, and 4 maintained a uniform particle size structure, while the bimetallic MOF powder prepared in Comparative Example 1 had an uneven particle size and severe agglomeration.

[0037] Figure 3 is a scanning electron microscope image of the product prepared in Comparative Example 2. As shown in Figure 3, with the increase of the molar ratio of Zn and Zr, the particle size of the bimetallic MOF powder prepared in Comparative Example 2 could no longer maintain a uniform size and gradually began to agglomerate.

[0038] Figure 4 shows the zinc ion transference number results of the zinc-symmetric battery assembled in Example 2. As shown in Figure 4, the zinc ion transference number of the zinc-symmetric battery based on the bimetallic MOF@Zn composite electrode assembled in Example 2 is 0.439. In Figure 4, the horizontal axis of the main graph represents time, and the vertical axis represents current density; the small graph in the upper right corner is the Nyquist plot of the electrochemical impedance spectroscopy: the horizontal axis is labeled to represent the real part of the impedance, and the vertical axis represents the imaginary part of the impedance. The Nyquist plot is used to analyze the kinetic information of the electrode process (such as charge transfer resistance, double layer capacitance, etc.). The horizontal and vertical axes together reflect the impedance characteristics of the electrode at different frequencies, and the "before" and "after" curves compare the changes in the system impedance before and after the experiment.

[0039] Figure 5 is a scanning electron microscope image of the zinc symmetric battery assembled in Example 2 after cycling; as shown in Figure 5, no obvious dendrites were formed on the surface of the bimetallic MOF@Zn composite electrode prepared in Example 2 after cycling.

[0040] Figure 6 shows the cycle stability curves of the zinc full cell assembled in Example 2; as shown in Figure 6, the bimetallic MOF@Zn composite electrode prepared in Example 2, at 1 A g -1 At the specified current density, after 200 charge-discharge cycles, the specific capacity of the zinc-ion battery is 108.8 mAh g⁻¹. -1 In Figure 5, the horizontal axis (X-axis) represents the Cycle Number, indicating the number of charge-discharge cycles the battery has undergone, ranging from 0 to 200. The vertical axis (Y-axis) shows: Left side: Specific Capacity, measured in milliampere-hours per gram. Specific capacity refers to the amount of electricity that a unit mass of electrode material can provide, reflecting the energy storage capacity of the battery's electrode material. Right side: Coulombic Efficiency (%), measured as a percentage. Coulombic efficiency refers to the ratio of discharge capacity to charge capacity during charge-discharge processes, reflecting the energy loss during charging and discharging. A higher coulombic efficiency indicates less energy loss during charging and discharging.

[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a zinc anode protective layer based on the regulation of zinc ion transport using bimetallic MOF channels, characterized in that, The preparation method includes: Step 1. Uniformly mixing zirconium salt, zinc salt and a first organic solvent to obtain a first mixed solution; Step 2. Uniformly mixing the first mixed solution with an organic ligand to obtain a second mixed solution; Step 3. Transferring the second mixed solution to a reaction vessel for solvothermal reaction; Step 4. After the reaction, the product obtained is washed multiple times with a second organic solvent and deionized water, dried, and obtained bimetallic MOF powder; Step 5. Mixing the bimetallic MOF powder with polyvinylidene fluoride in a third organic solvent to form a slurry, coating the slurry onto the surface of zinc foil, and drying it as a zinc negative electrode protective layer; In Step 1, the molar ratio of Zn to Zr is 5~40:

100.

2. The method for preparing a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport according to claim 1, characterized in that, The following features must be satisfied: in step 1, the molar ratio of Zn to Zr is 5~20:100; in step 1, the zirconium salt is selected from at least one of zirconium tetrachloride and zirconium nitrate; in step 1, the zinc salt is selected from at least one of zinc chloride, zinc nitrate, and zinc acetate; in step 2, the molar ratio of metal salt to organic ligand is 0.9~1.1:1 based on the total molar number of Zn ions and Zr ions.

3. The method for preparing a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport according to claim 1, characterized in that, In step 2, the organic ligand is at least one of terephthalic acid, 2-amino-1,4-phthalic acid, and 2,5-dihydroxyterephthalic acid.

4. The method for preparing a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport according to claim 1, characterized in that, In step 3, the reaction temperature is 100~150℃ and the reaction time is 12~48 h.

5. The method for preparing a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport according to claim 1, characterized in that, The mixture must satisfy at least one of the following characteristics: In step 1, the mixture is uniformly mixed by stirring at a speed of 400-500 rpm for 20-40 min; in step 2, the mixture is uniformly mixed by stirring at a speed of 400-500 rpm for 20-40 min; optionally, ultrasonic treatment is performed simultaneously with stirring; in steps 1 and 2, the drying method is vacuum drying; in step 3, the lining of the reaction vessel is polytetrafluoroethylene; in step 1, the first organic solvent includes N,N-dimethylformamide and optionally hydrochloric acid; in step 4, the second organic solvent is N,N-dimethylformamide; in step 5, the third organic solvent is N-methylpyrrolidone.

6. The method for preparing a zinc anode protective layer based on bimetallic MOF channel-regulated zinc ion transport according to claim 1, characterized in that, In step 5, the mass ratio of bimetallic MOF powder to polyvinylidene fluoride is 8-10:

1.

7. A zinc negative electrode protective layer, characterized in that, The zinc anode protective layer is prepared by the preparation method described in any one of claims 1-6.

8. A composite zinc anode, characterized in that, The composite zinc anode includes the zinc anode protective layer as described in claim 7.

9. The composite zinc anode according to claim 8, characterized in that, The thickness of the zinc anode protective layer is 10~20 μm.

10. An aqueous zinc metal battery, characterized in that, The aqueous zinc metal battery includes the composite zinc anode as described in claim 8 or 9.

Images