MOF-rGO composite modified zinc negative electrode and preparation method and application thereof

Abstract

The invention provides an MOF-rGO composite modified zinc negative electrode as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing rGO dispersion liquid by taking GO as a raw material, and loading rGO in the rGO dispersion liquid to the surface of zinc foil by adopting an L-B self-assembly method to obtain rGO modified zinc foil; and carrying out first impregnation on the rGO modified zinc foil in a zinc salt solution, and then carrying out second impregnation in an organic ligand solution to obtain the MOF-rGO composite modified zinc negative electrode. Directional arrangement of rGO on the surface of the zinc foil is achieved through L-B self-assembly, the obtained rGO modification layer is compact and stable, MOF is synthesized on the surface of the material in situ without using a binder on the basis, growth of dendritic crystals is effectively inhibited through the synergistic effect that rGO provides a conductive network and MOF regulates and controls zinc ion diffusion, and the preparation method has the advantages that the preparation process is simple, and the preparation cost is low. Therefore, the cycle performance and the energy density of the battery are remarkably improved, the short circuit of the battery is reduced, and industrial mass production is adapted.

Description

Technical Field

[0001] This invention relates to the field of zinc-based battery technology, and more specifically, to a MOF-rGO composite modified zinc anode, its preparation method, and its application. Background Technology

[0002] Rechargeable aqueous zinc-based batteries are considered one of the most promising large-scale energy storage devices due to their advantages such as environmental friendliness, low cost, high power / energy density, and safety (they do not use flammable and toxic organic liquid electrolytes). However, zinc-based batteries face many challenges during the electrostripping / electrodeposition process, including unlimited volume variation and dendrite growth. These problems lead to poor cycle stability and susceptibility to short circuits, thus limiting the application of zinc-based batteries.

[0003] In the prior art, one improvement method is to use zinc metal to spontaneously reduce graphene oxide (GO) to form a layered film on the zinc foil surface. However, the adhesion of the reduced graphene oxide (rGO) modification layer obtained by this method is insufficient, and it is easy to fall off after drying, resulting in poor electrode structure stability and affecting the cycle performance of the battery.

[0004] Another approach to improvement is to use metal-organic frameworks (MOFs) to stabilize the zinc metal anode. The channel size of MOFs is a key control factor, which can balance the zinc ion flux and zinc ion desolvation behavior within the channel and between grain boundaries. However, current MOF@Zn anodes are prepared by coating untreated zinc foil with a slurry made of MOF and polytetrafluoroethylene (PVDF) and then vacuum drying. The use of binders results in a large modification layer thickness, increasing the weight and volume of the zinc electrode, thereby reducing the energy density of the zinc battery.

[0005] In addition, the production processes of the aforementioned existing technologies are complex and the reaction conditions are harsh, making it difficult to achieve continuous production, resulting in low production efficiency and high costs. Summary of the Invention

[0006] The main objective of this invention is to provide a MOF-rGO composite modified zinc anode, its preparation method, and its application, in order to solve the problems of poor electrode structure stability, limited cycle performance and energy density, easy short circuit, and unsuitability for large-scale industrial production of modified zinc anodes in the prior art.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a MOF-rGO composite modified zinc anode is provided, comprising the following steps: Step S1, mixing graphene oxide with a reducing agent and water to carry out a reduction reaction to obtain a reduction solution; washing the reduction solution with an alcohol dispersant to obtain rGO; dispersing rGO in an alcohol dispersant to obtain an rGO dispersion; Step S2, using the LB self-assembly method, loading rGO in the rGO dispersion onto the surface of a zinc foil to obtain an rGO-modified zinc foil; Step S3, subjecting the rGO-modified zinc foil to a first impregnation in a zinc salt solution, followed by a second impregnation in an organic ligand solution, and drying to obtain a MOF-rGO composite modified zinc anode.

[0008] Further, step S2 includes: adding water to the reaction vessel, placing zinc foil against the side wall of the reaction vessel in the vertical direction, with the zinc foil below the water surface; dropping rGO dispersion onto the water surface along the side wall of the reaction vessel in the vertical direction furthest from the zinc foil; lifting the zinc foil upwards until it leaves the liquid surface, drying it, and obtaining rGO-modified zinc foil.

[0009] Furthermore, in step S2, the ratio of zinc foil to rGO is 1 cm. 2 (3-6 mg); and / or the thickness of the zinc foil is 100-200 μm; and / or the dropping rate of the rGO dispersion is 0.02-0.05 mL / s; and / or the upward pulling speed of the zinc foil is 3-7 mm / s.

[0010] Furthermore, in step S2, the drying temperature is 45–55°C and the drying time is 0.5–1.5 h; and / or before step S2, the zinc foil is further polished sequentially using 2000-grit sandpaper and a 10000-grit polishing plate.

[0011] Further, in step S1, the weight ratio of graphene oxide to reducing agent is 1:(8-12); and / or the reducing agent includes one or more of ascorbic acid, hydrazine hydrate and ethylenediamine; and / or the alcohol dispersant includes anhydrous ethanol and / or methanol; and / or the temperature of the reduction reaction is 60-70°C and the time is 35-45 min.

[0012] Furthermore, in step S1, the mass concentration of the rGO dispersion is 2.5–3.5 mg·mL. -1 ; and / or step S1 further includes the following steps: after mixing graphene oxide and reducing agent, adjust the pH of the solution to 8-12; and / or step S1 further includes the following steps: first wash the reduction solution with water until the solution pH is 6.5-7.5, and then wash it 3-5 times with an alcohol dispersant to obtain rGO.

[0013] Further, in step S3, the zinc salt includes Zn(Ac)2·2H2O and / or Zn(NO3)2·6H2O; and / or the organic ligand includes one or more of 2-methylimidazolium, terephthalic acid, and trimesic acid; and / or the molar ratio of zinc salt to organic ligand is (0.15–0.3):1; and / or the ratio of rGO-modified zinc foil to organic ligand is 1 cm³. 2 (0.04~0.06mmol).

[0014] Further, in step S3, the temperature of the first impregnation is 20-30°C and the time is 1-2 hours; and / or the temperature of the second impregnation is 20-30°C and the time is 1-2 hours.

[0015] According to another aspect of the present invention, a MOF-rGO composite modified zinc anode is provided, which is obtained using the preparation method described above.

[0016] According to another aspect of the present invention, a zinc-based battery is provided, comprising the MOF-rGO composite modified zinc anode described above.

[0017] By applying the technical solution of this invention, directional arrangement of rGO on the zinc foil surface is achieved through LB self-assembly. The resulting rGO modification layer is dense and stable, avoiding the problem of modification layer detachment. Furthermore, MOF is synthesized in situ on the material surface, eliminating the need for binders in the zinc electrode. The modification layer thickness is small, minimizing its impact on battery energy density. This invention achieves the integration of a conductive network provided by rGO and MOF-regulated Zn through molecular-level interface design and size effect modulation. 2+ The synergistic effect of diffusion effectively suppresses dendrite growth, thereby significantly improving electrode structural stability, battery cycle performance, and energy density, and reducing battery short circuits. The preparation process of this invention is simple, the reaction conditions are mild, the entire process involves solution processing, it is suitable for roll-to-roll production, has the potential for continuous production, and can reduce production costs and improve production efficiency. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A schematic diagram of the structure of a MOF-rGO composite modified zinc anode according to an embodiment of the present invention is shown;

[0020] Figure 2 A schematic diagram of the LB self-assembly process according to an embodiment of the present invention is shown;

[0021] Figure 3SEM characterization of zinc anodes according to Example 1 (MOF-rGO@Zn), Comparative Example 1 (Bare Zn), and Comparative Example 2 (rGO@Zn) are shown.

[0022] Figure 4 The charge-discharge curves of zinc symmetric batteries according to Embodiment 1 (MOF-rGO@Zn), Comparative Example 1 (Bare Zn), and Comparative Example 2 (rGO@Zn) are shown.

[0023] The above figures include the following reference numerals:

[0024] 1. Zinc foil; 2. rGO layer; 3. MOF layer; 4. Zinc ions. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Terminology Explanation:

[0027] LB (Langmuir-Blodgett) self-assembly method: This method involves arranging insoluble molecules in a tight and orderly manner at the gas-liquid interface to form a monolayer, and then transferring this monolayer onto a solid substrate to form a thin film with a highly ordered structure.

[0028] Unless otherwise specified, "room temperature" in this invention refers to 20–30°C.

[0029] As described in the background section of this invention, existing technologies suffer from problems such as poor stability of the rGO modification layer in modified zinc anodes, the need for binders in MOF modification layers, resulting in poor electrode structure stability, limited battery cycle performance and energy density, and susceptibility to short circuits, making them unsuitable for large-scale industrial production. To address these issues, in a typical embodiment of this invention, a method for preparing a MOF-rGO composite modified zinc anode is provided, comprising the following steps: Step S1, mixing graphene oxide with a reducing agent and water to perform a reduction reaction, obtaining a reduction solution; washing the reduction solution with an alcohol dispersant to obtain rGO; dispersing rGO in the alcohol dispersant to obtain an rGO dispersion; Step S2, using the LB self-assembly method, loading the rGO in the rGO dispersion onto the surface of a zinc foil to obtain an rGO-modified zinc foil; Step S3, subjecting the rGO-modified zinc foil to a first impregnation in a zinc salt solution, followed by a second impregnation in an organic ligand solution, and drying to obtain the MOF-rGO composite modified zinc anode.

[0030] In MOF-rGO composite modified zinc anodes, the zinc foil substrate provides the basic structure of the battery anode, and the dense and stable adhesion of the rGO modification layer is crucial for improving the surface properties of the zinc foil and enhancing the stability of the electrode structure. The in-situ growth of the MOF nanoparticle composite layer is directly related to the regulation of Zn in the zinc anode. 2+ It has the functions of diffusion and inhibiting dendrite growth.

[0031] This invention first mixes GO with a reducing agent and water to carry out a reduction reaction. During this process, the oxygen-containing functional groups on the surface of GO gradually decrease, and the sp... 2 The hybrid structure is gradually restored, and the carbon-oxygen mass ratio (C / O ratio) is significantly improved, resulting in a reduced solution containing rGO. The reduced solution is washed with an alcohol dispersant, and the obtained rGO is dispersed in the alcohol dispersant to obtain an rGO dispersion.

[0032] Then, using the LB self-assembly method, rGO in the rGO dispersion was loaded onto the surface of zinc foil. The zinc foil surface carries a positive charge, while the rGO surface, containing a small number of oxygen-containing functional groups, carries a certain negative charge. rGO and the zinc foil surface are bonded through electrostatic interactions. Simultaneously, the Zn atoms on the zinc foil surface can further reduce some of the oxygen-containing functional groups on the rGO surface, enhancing the bonding force between rGO and the zinc foil, allowing rGO to transfer to the zinc foil surface, resulting in rGO-modified zinc foil (rGO@Zn).

[0033] Finally, the rGO-modified zinc foil was first impregnated in a zinc salt solution, and then secondly impregnated in an organic ligand solution. During this process, the organic ligands and zinc ions undergo coordination reactions to form coordination structures, which are the structural units of MOF. As the coordination reaction between the organic ligands and zinc ions progresses, MOF nanocrystals are gradually formed. Compared to the zinc foil surface, the rGO surface can adsorb more divalent zinc ions, thereby attracting organic ligands for coordination. Therefore, MOF is preferentially loaded on the rGO surface. After drying, the MOF-rGO composite modified zinc anode (MOF-rGO@Zn) is obtained. It should be noted that, in order to fully load the MOF onto the rGO@Zn surface, a slight excess of zinc salt and organic ligands is added. This is understandable to those skilled in the art and will not be elaborated further here.

[0034] The LB self-assembly method can be used to load rGO in the rGO dispersion onto one side of the zinc foil or onto both sides of the zinc foil. In order to make the prepared composite modified zinc anode more suitable for zinc-based batteries, it is preferred to load rGO onto one side of the zinc foil. In this case, the MOF-rGO composite modified zinc anode includes zinc foil, rGO layer and MOF layer stacked in sequence.

[0035] This invention utilizes a composite material of rGO and MOF to modify zinc foil, which, when used as a zinc anode in zinc-based batteries, can achieve the desired Zn concentration in the electrolyte. 2+ Synergistic regulation of diffusion and deposition processes at the electrode / electrolyte interface. Without MOF interaction, rGO@Zn exhibits numerous active sites on its surface and interior. Defects and functional groups in rGO lead to uneven local charge density, with some regions exhibiting high conductivity, thus affecting the Zn concentration in the electrolyte. 2+ The adsorption and reduction processes are accelerated, making it easier to form zinc metal nuclei. Simultaneously, the rapid deposition and nucleation processes cause Zn... 2+ Zn cannot diffuse effectively within a two-dimensional plane, resulting in uneven Zn metal deposition and a tendency to form dendrites. MOFs can be used to further control the diffusion of Zn. 2+ The transport behavior of Zn before it enters the rGO and zinc metal regions and gains electrons is modified by utilizing the internal channels of the MOF. 2+ Solvation structure, controlling Zn 2+ transmission.

[0036] The above preparation method employs molecular-level interface design, utilizing LB self-assembly to achieve directional arrangement of rGO, exposing more functional groups to anchor the MOF precursor (i.e., organic ligands). Compared with commonly used methods such as freeze-drying and static self-assembly, the rGO-modified layer prepared by LB self-assembly is more compact and less prone to detachment after drying. This avoids interlayer compression and loose structure caused by excessive rGO, as well as the problem of insufficient rGO leading to difficulty in forming a continuous and stable interface. Furthermore, it eliminates the need for binders, allowing for in-situ synthesis of MOF materials. The MOF particle size in the MOF-rGO composite modified zinc anode is 50–70 nm. Compared to commonly used coating methods, the zinc electrode of this invention does not require binders, has a thinner modified layer, and has less impact on battery energy density. In addition, it exhibits a synergistic effect, where rGO provides the conductive network, and MOF modulates Zn. 2+ Diffusion and synergistic suppression of dendrite growth significantly improve electrode structural stability, battery cycle performance, and energy density, while reducing battery short circuits. The preparation method of this invention has high potential for continuous production, featuring a simple process, mild reaction conditions, and end-to-end solution processing, making it suitable for roll-to-roll production. In summary, the MOF-rGO composite modified zinc anode preparation method of this invention can enhance the stability of the modified layer, eliminate binder dependence, achieve composite synergistic regulation, and simplify the process for continuous production.

[0037] The core of the LB self-assembly method lies in utilizing intermolecular forces (such as electrostatic forces, hydrogen bonds, van der Waals forces, etc.) to transfer a monolayer from the air / water interface to a solid substrate, thereby achieving the ordered assembly of molecules. In a preferred embodiment, such as Figure 2As shown, step S2 includes: adding water to the reaction vessel, placing zinc foil against the side wall of the reaction vessel in the vertical direction, with the zinc foil below the water surface; dropping the rGO dispersion onto the water surface along the side wall of the reaction vessel in the vertical direction furthest from the zinc foil, at which point an interface is formed between the water added to the reaction vessel and the alcohol dispersant in the rGO dispersion; lifting the zinc foil upwards until it leaves the liquid surface, drying it, and obtaining the rGO-modified zinc foil.

[0038] The aforementioned LB self-assembly method can further promote the uniform and directional deposition of rGO monolayers on the zinc foil surface, rather than forming loose multilayer stacks. This further improves the adhesion between the rGO layer and the zinc foil, reduces the risk of rGO layer shrinkage or detachment during drying, and enhances the stability of the modified zinc anode. Due to the further improvement in the density of the rGO layer, the flatness of the zinc foil surface is improved, which is more conducive to the subsequent in-situ uniform growth of MOF materials. No additional binder is needed; MOF particles are directly synthesized in-situ on the rGO layer, forming a thinner and more uniform composite layer, thereby reducing the battery's internal resistance and weight, and increasing energy density. Furthermore, the rGO layer obtained by the above method not only provides a good conductive network but can also serve as a template to guide the directional growth of MOFs. The synergistic effect of these two factors is more conducive to controlling the growth of Zn. 2+ The diffusion path and deposition behavior are optimized to suppress dendrite formation and extend battery cycle life. Solution processing is also easier to scale up for industrial production, further improving production efficiency.

[0039] In a preferred embodiment, in step S2, the ratio of zinc foil to rGO is 1 cm. 2 The concentration of rGO is 3–6 mg / mL; and / or the thickness of the zinc foil is 100–200 μm; and / or the dropping rate of the rGO dispersion is 0.02–0.05 mL / s; and / or the upward pulling speed of the zinc foil is 3–7 mm / s. When the ratio of zinc foil to rGO is within the above range, it is beneficial for rGO to cover the zinc foil surface at a more appropriate concentration, thereby forming a continuous and stable interface and improving the stability and conductivity of the modified layer. Under the above ratio conditions, based on the matching of active sites on the surface of rGO and zinc foil, rGO molecules can be more tightly arranged, forming a highly ordered monolayer or few-layer structure, thereby further enhancing the bonding force between the rGO layer and the zinc foil. When the mass concentration of the rGO dispersion is 2.5–3.5 mg / mL... -1 At that time, the ratio of zinc foil to rGO dispersion was 1 cm. 2 (1-1.7 mL).

[0040] The dropping rate of the rGO dispersion and the zinc foil pulling rate are key steps in the LB self-assembly process. Controlling the dropping rate affects the extent to which rGO molecules spread on the water surface and the formation of a monolayer, while the pulling rate affects the integrity and uniformity of the rGO molecular layer transferred to the zinc foil surface. Within the specified parameter range, it is beneficial to promote the directional alignment and tight adsorption of rGO, forming a highly stable rGO-modified layer. This reduces uneven or excessively thin rGO layer thickness caused by excessively fast pulling speeds, and interlayer stacking caused by excessively slow pulling speeds. This results in better uniformity and thickness of the rGO layer, providing a more ideal substrate for subsequent in-situ MOF growth. Without a binder, MOF particles can grow uniformly on the rGO layer, forming a stable, conductive composite layer with size effects, effectively controlling the growth of Zn. 2+ The deposition behavior inhibits dendrite growth.

[0041] In a preferred embodiment, in step S2, the drying temperature is 45–55°C, and the drying time is 0.5–1.5 h; and / or before step S2, the process further includes polishing the zinc foil sequentially with 2000-grit sandpaper and a 10000-grit polishing plate. Under the above drying conditions, moisture between the rGO layers can be effectively removed, preventing excessive porosity from affecting MOF growth, while maintaining the stability of rGO and the strength of the rGO-Zn interface, thus improving the density and stability of the rGO modified layer. The purpose of the zinc foil polishing pretreatment is to remove impurities such as the surface oxide layer, improve surface roughness and cleanliness, and expose more active sites, which can form more stable chemical bonds with the functional groups of the rGO molecules.

[0042] The weight ratio of graphene oxide to reducing agent affects the efficiency of the reduction reaction. In a preferred embodiment, in step S1, the weight ratio of graphene oxide to reducing agent is 1:(8-12); and / or the reducing agent includes one or more of ascorbic acid, hydrazine hydrate, and ethylenediamine; and / or the alcohol dispersant includes anhydrous ethanol and / or methanol; and / or the temperature of the reduction reaction is 60-70°C, and the time is 35-45 min. A high proportion of reducing agent can promote the full reduction of oxidizing functional groups in GO, improve the conductivity of rGO, and reduce side reactions caused by excessive reducing agent, such as over-reduction or structural damage of graphene oxide, so that rGO has a better microstructure and stability, providing more suitable surface active sites for subsequent loading on the zinc foil surface and as a MOF growth substrate. The above-mentioned reducing agents not only have strong reducing power and can effectively convert GO into rGO, but also form stable chemical bonds with defects and functional groups on the GO surface during the reaction process, further enhancing the adhesion between rGO and zinc foil and improving the stability of the modified layer. The mild reducing properties of the aforementioned reducing agents also help control the reaction rate and reduce the damage to the material structure caused by violent reactions.

[0043] Using the aforementioned types of alcohol dispersants is beneficial for the uniform dispersion and stability of rGO, improving the density and uniformity of the rGO modified layer. The reduction reaction conditions described above can increase the reaction rate while achieving a more moderate degree of reduction. By controlling the reaction time, the degree of reduction of graphene oxide can be controlled, forming highly reduced rGO with minimal side reactions and optimal stability and conductivity of the rGO layer.

[0044] In a preferred embodiment, in step S1, the mass concentration of the rGO dispersion is 2.5–3.5 mg·mL. -1 ; and / or step S1 further includes the following steps: after mixing graphene oxide and a reducing agent, adjusting the pH of the solution to 8–12; and / or step S1 further includes the following steps: first washing the reducing solution with water until the solution pH is 6.5–7.5, then washing it 3–5 times with an alcohol dispersant to obtain rGO. The above-mentioned rGO dispersion concentration is beneficial for the formation of a uniform and dense monolayer during LB self-assembly, and can also reduce precipitation or agglomeration caused by excessive concentration. A suitable concentration range can increase the contact opportunity between rGO and the active sites on the zinc foil surface, enhance the intermolecular affinity, thereby forming a more stable and stronger-adhesive rGO modified layer, which is beneficial for the subsequent in-situ growth of MOF without additional binders.

[0045] Adjusting the solution pH to alkaline optimizes the reaction environment between the reducing agent and GO, enhancing reduction efficiency while also adjusting the charge state of the GO surface, making it more susceptible to electron acceptance, accelerating the reduction process, and forming rGO with higher conductivity. Furthermore, in a slightly alkaline pH environment, the functional groups on the rGO surface tend to form a negatively charged state, which can electrostatically attract the positively charged sites on the zinc foil surface, further enhancing the binding stability of the rGO modification layer. Adjusting the pH of the reduced rGO to neutral helps remove reaction byproducts and unreacted reducing agent, reducing the interference of these residues on subsequent MOF growth. Simultaneously, it ensures the relative stability of the rGO surface's chemical properties, not affecting its binding with the MOF precursor and the uniform growth of the MOF, thereby improving the overall structural stability and performance of the modified zinc anode.

[0046] The molar ratio of zinc salt to organic ligand affects the type, particle size, and uniformity of MOF materials. In a preferred embodiment, in step S3, the zinc salt includes Zn(Ac)₂·2H₂O and / or Zn(NO₃)₂·6H₂O; and / or the organic ligand includes one or more of 2-methylimidazolium, terephthalic acid, and trimesic acid; and / or the molar ratio of zinc salt to organic ligand is (0.15–0.3):1; and / or the ratio of rGO-modified zinc foil to organic ligand is 1 cm⁻¹. 2(0.04~0.06mmol). Among them, the organic ligands 2-methylimidazolium, terephthalic acid, and trimesoic acid can undergo coordination reactions with zinc ions to form coordination structures of Zn(2-MeIm)2, Zn(BDC), and Zn3(BTC)2.

[0047] The aforementioned zinc salts and organic ligands, when used in appropriate proportions, can efficiently generate MOF materials with high specific surface area and good porosity on the rGO surface, which is more conducive to regulating Zn content. 2+ The role of ion diffusion pathways and deposition processes. Within the aforementioned molar ratio range, it is beneficial to promote the full reaction of zinc salts and organic ligands, reduce heterogeneous nucleation during MOF growth, obtain MOF layers with uniform particle size and distribution, enhance their bonding with the rGO-modified layer, and form a stable composite structure without binders. Furthermore, it helps to balance the reaction rate and the growth uniformity of MOF particles, resulting in MOF layers with ideal particle size and pore size distributions, thereby enabling more effective control of Zn. 2+ The diffusion behavior of ions inhibits dendrite formation.

[0048] Within the aforementioned range, the ratio of rGO-modified zinc foil to organic ligands facilitates a balance between the conductive network of the rGO layer and the ion transport regulation capability of the MOF layer. An appropriate ratio not only provides sufficient active sites for MOF growth but also results in a more suitable rGO layer thickness, providing a stable substrate for the uniform distribution of MOF particles. The conductivity of rGO and the structural properties of MOF synergistically suppress dendrite growth, improving the stability and electrochemical performance of the zinc electrode structure, thereby enhancing the cycle performance and energy density of the battery. These conditions also simplify the preparation process of the MOF-modified layer, avoiding the use of traditional binders, which helps reduce manufacturing costs and improve production efficiency. The entire preparation process is more gentle and controllable, facilitating continuous and large-scale production, and meeting the demands of industrial mass production for low-cost, high-efficiency, and high-performance materials.

[0049] By controlling the impregnation time and solution concentration, the growth rate and crystal size of the MOF can be adjusted. In a preferred embodiment, in step S3, the temperature of the first impregnation is 20–30°C, and the time is 1–2 h; and / or the temperature of the second impregnation is 20–30°C, and the time is 1–2 h. Under the above impregnation conditions, sufficient reaction and diffusion control are facilitated during the MOF material growth process. Zinc salt and organic ligand molecules can be effectively adsorbed and assembled on the rGO surface to form a uniformly covered MOF layer. Within the above time window, the MOF material can diffuse along the surface of the rGO layer, filling the pores, thereby enhancing the interfacial bonding between the MOF and rGO, and improving the overall stability of the electrode structure without the need for additional binders. For similar reasons, it is further preferred that the ratio of the first impregnation time to the second impregnation time is 1:(0.8–1.2).

[0050] The concentrations of the zinc salt and organic ligand solutions are not limited, as long as the amounts of zinc salt and organic ligands added meet the aforementioned ranges. The solvent for the zinc salt and organic ligand solutions can be one or more of methanol, ethanol, and N,N-dimethylformamide. Selecting a specific solvent not only facilitates the dissolution of zinc salt and organic ligands but also promotes their reaction based on good solubility, resulting in high-quality MOF materials. The volatility of the solvent also facilitates the subsequent drying process, reducing impurity residues and improving production efficiency.

[0051] In another typical embodiment of the present invention, a MOF-rGO composite modified zinc anode is also provided, obtained using the preparation method described above. Due to the use of the preparation method of the present invention, the rGO modification layer in the modified zinc anode exhibits good stability, the MOF modification layer does not require a binder, the electrode structure has good stability, the battery's cycle performance and energy density are improved, the battery is less prone to short circuits, and it has better adaptability for large-scale industrial production.

[0052] In another typical embodiment of the present invention, a zinc-based battery is also provided, comprising the MOF-rGO composite modified zinc anode described above. Preferably, the zinc-based battery is an aqueous zinc-based battery. The MOF-rGO composite modified zinc anode provided by the present invention can significantly improve the performance indicators of aqueous zinc-based batteries, including cycle performance and energy density, while reducing short-circuit phenomena, simplifying the production process, and reducing costs, which is conducive to realizing high-performance, long-life, and low-cost aqueous zinc batteries.

[0053] Typically, but not limitingly, in step S1, the weight ratio of graphene oxide to reducing agent is 1:8, 1:8.5, 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, or any two of these values.

[0054] Typically, but not limitingly, in step S1, the temperature of the reduction reaction is 60°C, 62°C, 64°C, 65°C, 66°C, 68°C, 70°C or any two of these values, and the time is 35 min, 36 min, 38 min, 40 min, 42 min, 44 min, 45 min or any two of these values.

[0055] Typically, but not limitingly, in step S2, the ratio of zinc foil to rGO is 1 cm. 2 3mg, 1cm 2 3.5mg, 1cm 2 4mg, 1cm 2 4.5mg, 1cm 2 5mg, 1cm 2 5.5mg, 1cm 2 6mg or a range of any two values ​​thereof.

[0056] Typically, but not limitingly, in step S2, the dropping rate of the rGO dispersion is 0.02 mL / s, 0.025 mL / s, 0.03 mL / s, 0.035 mL / s, 0.04 mL / s, 0.045 mL / s, 0.05 mL / s, or any two of these values.

[0057] Typically, but not limitingly, in step S2, the zinc foil is pulled upward at a speed of 3 mm / s, 4 mm / s, 5 mm / s, 6 mm / s, 7 mm / s, or any two of these values.

[0058] Typically, but not limitingly, in step S2, the drying temperature is 45°C, 46°C, 48°C, 50°C, 52°C, 54°C, 55°C or any two of these values, and the drying time is 0.5h, 0.6h, 0.8h, 1.0h, 1.2h, 1.4h, 1.5h or any two of these values.

[0059] Typically, but not limitingly, in step S3, the molar ratio of zinc salt to organic ligand is 0.15:1, 0.18:1, 0.2:1, 0.22:1, 0.25:1, 0.28:1, 0.3:1, or any two of these values ​​within a range.

[0060] Typically, but not limitingly, in step S3, the ratio of rGO-modified zinc foil to organic ligand is 1 cm⁻¹. 2 0.04 mmol, 1 cm 2 0.045 mmol, 1 cm 2 0.05 mmol, 1 cm 2 0.055 mmol, 1 cm2 :0.06 mmol or any two of its values.

[0061] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0062] Example 1

[0063] Step S1: Prepare reduced graphene oxide using graphene oxide as raw material. Add 15 mL of graphene oxide aqueous dispersion (5 mg / mL) to 110 mL of deionized water, then add 0.75 g of ascorbic acid as a reducing agent, with a weight ratio of graphene oxide to reducing agent of 1:10. Adjust the pH to approximately 10 using ammonia water, and reduce the graphene oxide using the reducing agent under weakly alkaline conditions. Control the reaction temperature at 65℃ and the reaction time at 40 minutes to obtain a reduced solution. After the reaction, wash the precipitated rGO with deionized water until neutral using filtration and washing. Then, wash three times with anhydrous ethanol to replace the water with anhydrous ethanol to facilitate subsequent self-assembly processes, obtaining rGO. Sonicately disperse the obtained rGO in anhydrous ethanol to finally obtain a uniformly dispersed rGO dispersion with a mass concentration of approximately 3 mg / mL. -1 .

[0064] Step S2: rGO is loaded onto the zinc foil surface using the LB self-assembly method. First, a 150μm thick zinc foil is sequentially polished with 2000-grit sandpaper and a 10000-grit polishing plate to remove surface oxide layers and other impurities. Then, 250mL of deionized water is added to a beaker, with the zinc foil placed against the vertical wall of the beaker, submerged below the water surface. Using a dropper, an appropriate amount of rGO dispersion is slowly dripped onto the water surface along the vertical side of the beaker furthest from the zinc foil at a rate of 0.04mL / s, ensuring a zinc foil to rGO ratio of 1cm. 2 4.5 mg; slowly and uniformly pull the zinc foil upwards at a speed of 5 mm / s until it leaves the liquid surface; dry it in a 50°C forced-air drying oven for 1 hour to obtain rGO-modified zinc foil (rGO@Zn).

[0065] Step S3: MOF-rGO composite treatment of zinc foil surface. 0.1098 g of Zn(Ac)₂·2H₂O (0.5 mmol) was dissolved in 200 mL of methanol to obtain a zinc salt solution. Simultaneously, 0.164 g of 2-methylimidazole (2 mmol) was dissolved in 200 mL of methanol to obtain an organic ligand solution. rGO@Zn was placed in the zinc salt solution and allowed to stand for 1.5 hours, followed by immersion in the organic ligand solution and standing for 1.5 hours, allowing the MOF material to grow in situ on the rGO-modified zinc foil surface. The molar ratio of zinc salt to organic ligand was 0.25:1, and the ratio of rGO-modified zinc foil to organic ligand was 1 cm⁻¹. 2 0.05 mmol. After the reaction was complete, the zinc foil was removed, washed with methanol, and dried at room temperature to obtain the MOF-rGO composite modified zinc anode (MOF-rGO@Zn).

[0066] Example 2

[0067] The difference from Example 1 is as follows: In step S1, reduced graphene oxide is prepared using graphene oxide as a raw material. Aqueous dispersion of graphene oxide (5 mg / mL) is added to 110 mL of deionized water, followed by the addition of 0.75 g of ascorbic acid as a reducing agent. The weight ratio of graphene oxide to reducing agent is 1:8. The pH is adjusted to approximately 8 using ammonia. Graphene oxide is reduced under weakly alkaline conditions using the reducing agent. The reaction temperature is controlled at 60°C, and the reaction time is 45 minutes to obtain a reduced solution. After the reaction, the precipitated rGO is washed with deionized water until neutral using filtration and washing. Subsequently, it is washed three times with anhydrous ethanol to replace the water with anhydrous ethanol, facilitating subsequent self-assembly processes to obtain rGO. The rGO obtained by vacuum filtration is ultrasonically dispersed in anhydrous ethanol to finally obtain a uniformly dispersed rGO dispersion with a mass concentration of approximately 2.5 mg / mL. -1 .

[0068] Example 3

[0069] The difference from Example 1 is as follows: In step S1, reduced graphene oxide is prepared using graphene oxide as a raw material. Aqueous dispersion of graphene oxide (5 mg / mL) is added to 110 mL of deionized water, followed by the addition of 0.75 g of ascorbic acid as a reducing agent. The weight ratio of graphene oxide to reducing agent is 1:12. The pH is adjusted to approximately 12 using ammonia. Graphene oxide is reduced under weakly alkaline conditions using the reducing agent. The reaction temperature is controlled at 70°C, and the reaction time is 35 minutes to obtain a reduced solution. After the reaction, the precipitated rGO is washed with deionized water until neutral using filtration and washing. Subsequently, it is washed five times with anhydrous ethanol to replace the water with anhydrous ethanol for subsequent self-assembly processes, yielding rGO. The obtained rGO is ultrasonically dispersed in anhydrous ethanol to finally obtain a uniformly dispersed rGO dispersion with a mass concentration of approximately 3.5 mg / mL. -1 .

[0070] Example 4

[0071] The difference from Example 1 is that in step S2, rGO is loaded onto the zinc foil surface using the LB self-assembly method. First, a 150μm thick zinc foil is sequentially polished with 2000-grit sandpaper and a 10000-grit polishing plate to remove surface oxide layers and other impurities. Then, 250mL of deionized water is added to a beaker, and the zinc foil is placed against the vertical wall of the beaker, below the water surface. A suitable amount of rGO dispersion is drawn up with a dropper and slowly dripped onto the water surface at a rate of 0.02mL / s along the vertical side of the beaker furthest from the zinc foil, ensuring a zinc foil to rGO ratio of 1cm. 2 Add 3mg; slowly and uniformly lift the zinc foil upwards at a speed of 3mm / s until it leaves the liquid surface; dry in a 45℃ forced-air drying oven for 1.5 hours to obtain rGO-modified zinc foil (rGO@Zn).

[0072] Example 5

[0073] The difference from Example 1 is that in step S2, rGO is loaded onto the zinc foil surface using the LB self-assembly method. First, a 150μm thick zinc foil is sequentially polished with 2000-grit sandpaper and a 10000-grit polishing plate to remove surface oxide layers and other impurities. Then, 250mL of deionized water is added to a beaker, and the zinc foil is placed against the vertical wall of the beaker, below the water surface. A suitable amount of rGO dispersion is drawn up with a dropper and slowly dripped onto the water surface at a rate of 0.05mL / s along the vertical side of the beaker furthest from the zinc foil, ensuring a zinc foil to rGO ratio of 1cm. 2Add 6 mg of the solution and slowly lift the zinc foil upwards at a constant speed of 7 mm / s until it leaves the liquid surface. Dry the foil in a 55°C oven for 0.5 hours to obtain rGO-modified zinc foil (rGO@Zn).

[0074] Example 6

[0075] The difference from Example 1 is that in step S3, the zinc foil surface is treated with MOF-rGO composite. Zn(Ac)₂·2H₂O is dissolved in 200 mL of methanol to obtain a zinc salt solution. Simultaneously, 2-methylimidazole is dissolved in 200 mL of methanol to obtain an organic ligand solution. rGO@Zn is placed in the zinc salt solution and allowed to stand for 2 hours, then immersed in the organic ligand solution and allowed to stand for 2 hours, allowing the MOF material to grow in situ on the rGO-modified zinc foil surface. The molar ratio of zinc salt to organic ligand is 0.15:1, and the ratio of rGO-modified zinc foil to organic ligand is 1 cm⁻¹. 2 0.04 mmol. After the reaction was complete, the zinc foil was removed, washed with methanol, and dried at room temperature to obtain the MOF-rGO composite modified zinc anode (MOF-rGO@Zn).

[0076] Example 7

[0077] The difference from Example 1 is that in step S3, the zinc foil surface is treated with MOF-rGO composite. Zn(Ac)₂·2H₂O is dissolved in 200 mL of methanol to obtain a zinc salt solution. Simultaneously, 2-methylimidazole is dissolved in 200 mL of methanol to obtain an organic ligand solution. rGO@Zn is placed in the zinc salt solution and allowed to stand for 1 hour, then immersed in the organic ligand solution and allowed to stand for 1 hour, allowing the MOF material to grow in situ on the rGO-modified zinc foil surface. The molar ratio of zinc salt to organic ligand is 0.3:1, and the ratio of rGO-modified zinc foil to organic ligand is 1 cm⁻¹. 2 0.06 mmol. After the reaction was complete, the zinc foil was removed, washed with methanol, and dried at room temperature to obtain the MOF-rGO composite modified zinc anode (MOF-rGO@Zn).

[0078] Example 8

[0079] Step S1: Prepare reduced graphene oxide (rGO) using graphene oxide as a raw material. Add 15 mL of graphene oxide aqueous dispersion (5 mg / mL) to 110 mL of deionized water, then add 0.75 g of hydrazine hydrate as a reducing agent, with a weight ratio of graphene oxide to reducing agent of 1:10. Adjust the pH to approximately 10 using ammonia water, and reduce the graphene oxide using the reducing agent under weakly alkaline conditions. Control the reaction temperature at 65℃ and the reaction time at 40 minutes to obtain a reduced solution. After the reaction, wash the precipitated rGO with deionized water until neutral using filtration and washing. Then, wash three times with methanol to replace the water with methanol to facilitate subsequent self-assembly processes, obtaining rGO. Sonicately disperse the obtained rGO in methanol to finally obtain a uniformly dispersed rGO dispersion with a mass concentration of approximately 3 mg / mL. -1 .

[0080] Step S2: rGO is loaded onto the zinc foil surface using the LB self-assembly method. First, a 150μm thick zinc foil is sequentially polished with 2000-grit sandpaper and a 10000-grit polishing plate to remove surface oxide layers and other impurities. Then, 250mL of deionized water is added to a beaker, with the zinc foil placed against the vertical wall of the beaker, submerged below the water surface. Using a dropper, an appropriate amount of rGO dispersion is slowly dripped onto the water surface along the vertical side of the beaker furthest from the zinc foil at a rate of 0.04mL / s, ensuring a zinc foil to rGO ratio of 1cm. 2 4.5 mg; slowly and uniformly pull the zinc foil upwards at a speed of 5 mm / s until it leaves the liquid surface; dry it in a 50°C forced-air drying oven for 1 hour to obtain rGO-modified zinc foil (rGO@Zn).

[0081] Step S3: MOF-rGO composite treatment of zinc foil surface. Zn(Ac)₂·2H₂O was dissolved in 200 mL of ethanol to obtain a zinc salt solution. Simultaneously, terephthalic acid was dissolved in 200 mL of ethanol to obtain an organic ligand solution. rGO@Zn was placed in the zinc salt solution and allowed to stand for 1.5 hours, then immersed in the organic ligand solution and allowed to stand for 1.2 hours, allowing the MOF material to grow in situ on the rGO-modified zinc foil surface. The molar ratio of zinc salt to organic ligand was 0.25:1, and the ratio of rGO-modified zinc foil to organic ligand was 1 cm³. 2 0.05 mmol. After the reaction was complete, the zinc foil was removed, washed with methanol, and dried at room temperature to obtain the MOF-rGO composite modified zinc anode (MOF-rGO@Zn).

[0082] Example 9

[0083] Step S1: Prepare reduced graphene oxide (rGO) using graphene oxide as a raw material. Add 15 mL of graphene oxide aqueous dispersion (5 mg / mL) to 110 mL of deionized water, then add 0.75 g of ethylenediamine as a reducing agent, with a weight ratio of graphene oxide to reducing agent of 1:10. Adjust the pH to approximately 10 using ammonia water, and reduce the graphene oxide using the reducing agent under weakly alkaline conditions. Control the reaction temperature at 65℃ and the reaction time at 40 minutes to obtain a reduced solution. After the reaction, wash the precipitated rGO with deionized water until neutral using filtration and washing. Then, wash three times with methanol to replace the water with methanol to facilitate subsequent self-assembly processes, obtaining rGO. Disperse the obtained rGO by ultrasonication in methanol to finally obtain a uniformly dispersed rGO dispersion with a mass concentration of approximately 3 mg / mL. -1 .

[0084] Step S2: rGO is loaded onto the zinc foil surface using the LB self-assembly method. First, a 150μm thick zinc foil is sequentially polished with 2000-grit sandpaper and a 10000-grit polishing plate to remove surface oxide layers and other impurities. Then, 250mL of deionized water is added to a beaker, with the zinc foil placed against the vertical wall of the beaker, submerged below the water surface. Using a dropper, an appropriate amount of rGO dispersion is slowly dripped onto the water surface along the vertical side of the beaker furthest from the zinc foil at a rate of 0.04mL / s, ensuring a zinc foil to rGO ratio of 1cm. 2 4.5 mg; slowly and uniformly pull the zinc foil upwards at a speed of 5 mm / s until it leaves the liquid surface; dry it in a 50°C forced-air drying oven for 1 hour to obtain rGO-modified zinc foil (rGO@Zn).

[0085] Step S3: MOF-rGO composite treatment of zinc foil surface. Zn(NO3)2·6H2O was dissolved in 200 mL of N,N-dimethylformamide to obtain a zinc salt solution. Simultaneously, trimellitic acid was dissolved in 200 mL of N,N-dimethylformamide to obtain an organic ligand solution. rGO@Zn was placed in the zinc salt solution and allowed to stand for 1.5 hours, then immersed in the organic ligand solution and allowed to stand for 1.8 hours, allowing the MOF material to grow in situ on the rGO-modified zinc foil surface. The molar ratio of zinc salt to organic ligand was 0.25:1, and the ratio of rGO-modified zinc foil to organic ligand was 1 cm³. 2 0.05 mmol. After the reaction was complete, the zinc foil was removed, washed with methanol, and dried at room temperature to obtain the MOF-rGO composite modified zinc anode (MOF-rGO@Zn).

[0086] Comparative Example 1

[0087] The difference from Example 1 is that metallic zinc foil is used as the zinc negative electrode, that is, unmodified zinc foil (Bare Zn) is used.

[0088] Comparative Example 2

[0089] The difference from Example 1 is that step S3 was not performed, in which rGO-modified zinc foil (rGO@Zn) was used as the zinc anode.

[0090] Comparative Example 3

[0091] The difference from Example 1 is that steps S1 and S2 were omitted, and MOF-modified zinc foil (MOF@Zn) was used as the zinc anode: 0.1098 g of Zn(Ac)₂·2H₂O (0.5 mmol) was dissolved in 200 mL of methanol to obtain a zinc salt solution. Simultaneously, 0.164 g of 2-methylimidazole (2 mmol) was dissolved in 200 mL of methanol to obtain an organic ligand solution. The zinc salt solution and the organic ligand solution were rapidly mixed and stirred for 1.5 hours to obtain the MOF material. A slurry of MOF alcohol and polytetrafluoroethylene (PVDF) at a weight ratio of 8:2 was prepared, coated onto the untreated zinc foil, and then vacuum-dried at 60°C for 12 hours to prepare the material.

[0092] Comparative Example 4

[0093] The difference from Example 1 is that in step S2, a conventional method is used to load rGO: the zinc foil is polished sequentially with 2000-grit sandpaper and 10000-grit polishing plate to remove surface oxide layers and other impurities; then, 250 mL of rGO / anhydrous ethanol dispersion is added to a beaker, the zinc foil is placed in it for adsorption, and then freeze-dried to obtain rGO-modified zinc foil (rGO@Zn).

[0094] Performance testing:

[0095] MOF particle size in MOF-rGO composite modified zinc anode: The particle size was measured by SEM using a JEOL JSM-7800F field emission scanning electron microscope.

[0096] Electrochemical performance: Assembled coin cell zinc symmetric cells, both positive and negative electrodes are composite modified zinc foil, with a size of 1 cm. 2 The electrolyte was 2 mol / L ZnSO4, and the separator was a glass fiber membrane. The coin-type zinc symmetric battery was tested for charge-discharge curves using a Chenhua electrochemical workstation at a rate of 1 mA / cm². 2Discharge at a current density for 1 hour, followed by charging for 1 hour, constitutes one cycle. Record the overpotential of the first discharge cycle. A higher overpotential indicates that dendrites are more likely to form on the electrode material surface, resulting in poorer electrode stability. Simultaneously record the charge-discharge time before a sudden voltage change or overvoltage drop to near 0mV. A longer charge-discharge time indicates a longer cycle time before a short circuit, making the battery less prone to short circuits and exhibiting better cycle performance.

[0097] The test results of the above embodiments and comparative examples are shown in Table 1. A schematic diagram of the structure of the MOF-rGO composite modified zinc anode in Example 1 is shown in Table 1. Figure 1 As can be seen along the direction close to the electrolyte, it includes a zinc foil 1, an rGO layer 2, and a MOF layer 3 stacked sequentially, wherein the MOF layer 3 is in contact with zinc ions 4 in the electrolyte; the SEM characterization of the zinc anode of Example 1, Comparative Example 1, and Comparative Example 2 is shown in [reference needed]. Figure 3 The charge-discharge curves of zinc symmetric batteries in Example 1, Comparative Example 1, and Comparative Example 2 are shown below. Figure 4 .

[0098] Table 1

[0099]

[0100]

[0101] Depend on Figure 4 It can be seen that compared with the unmodified zinc foil (Bare Zn) in Comparative Example 1, the cycling stability of the rGO-modified zinc foil (rGO@Zn) in Comparative Example 2 is slightly improved, while the cycling stability of the MOF-rGO composite modified zinc anode (MOF-rGO@Zn) in Example 1 is significantly improved. By magnifying and analyzing the charge-discharge curves, it was found that during the first discharge, the zinc metal nucleation overpotential of rGO@Zn was 11 mV, while that of MOF-rGO@Zn was only 8 mV. This indicates that the energy barrier for Zn metal deposition on the surface of rGO@Zn is higher, potentially leading to larger crystal nuclei and a greater likelihood of dendrite formation. During the cycling process (60 hours), as shown by the dashed box in the figure, the zinc metal overpotential of rGO@Zn remained relatively high. The polarization potential of rGO@Zn was smaller in the early stages, but gradually increased after 95 hours, while the polarization voltage of MOF-rGO@Zn was more stable, especially after 100 hours, when the polarization potential was lower than that of rGO@Zn. In summary, rGO exhibits better conductivity than MOF-rGO; however, although its initial polarization is smaller, the numerous defects and oxygen-containing functional groups on its surface, compared to Zn, contribute to its disadvantage. 2+ High affinity, leading to Zn 2+Before diffusion in the two-dimensional direction, zinc metal rapidly forms, resulting in large zinc metal nuclei that evolve into dead zinc and dendrites. Interfacial ion transport is hindered, leading to increased internal resistance and polarization potential after 100 hours. In Comparative Example 3, the use of a binder inevitably results in a thicker modified layer, increasing the weight and volume of the zinc electrode and thus reducing the energy density of the zinc battery. In Comparative Example 4, the conventional method for preparing the rGO modified layer leads to insufficient adhesion, which in turn reduces the adhesion of the MOF modified layer. After drying, the composite modified layer easily detaches, resulting in poor electrode structural stability and a significant decrease in battery cycle performance.

[0102] As can be seen from the above, compared with the comparative examples, the embodiments of the present invention achieve the directional arrangement of rGO on the zinc foil surface through LB self-assembly. The resulting rGO modification layer is dense and stable, avoiding the problem of modification layer detachment. On this basis, MOF is synthesized in situ on the material surface, the zinc electrode does not require a binder, the modification layer thickness is small, and the impact on battery energy density is minimal. The present invention achieves the provision of a conductive network by rGO and the regulation of Zn by MOF through molecular-level interface design and size effect control. 2+ The synergistic effect of diffusion effectively suppresses dendrite growth, thereby significantly improving electrode structure stability, battery cycle performance and energy density, and reducing battery short circuits.

[0103] Furthermore, it can be seen that the overall effect is better when all process parameters are within the preferred range of the present invention.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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 MOF-rGO composite modified zinc anode, characterized in that, Includes the following steps: Step S1: Mix graphene oxide with a reducing agent and water to carry out a reduction reaction and obtain a reduced solution; The reduced solution was washed with an alcohol dispersant to obtain rGO; the rGO was dispersed in the alcohol dispersant to obtain an rGO dispersion. Step S2: Using the LB self-assembly method, rGO in the rGO dispersion is loaded onto the surface of zinc foil to obtain rGO-modified zinc foil; Step S3: The rGO-modified zinc foil is first impregnated in a zinc salt solution, then second impregnated in an organic ligand solution, and dried to obtain the MOF-rGO composite modified zinc anode.

2. The preparation method of the MOF-rGO composite modified zinc anode according to claim 1, characterized in that, Step S2 includes: adding water to a reaction vessel, placing the zinc foil against the side wall of the reaction vessel in the vertical direction, with the zinc foil below the water surface; dropping the rGO dispersion onto the water surface along the side wall of the reaction vessel furthest from the zinc foil in the vertical direction; lifting the zinc foil upwards until it leaves the liquid surface, and drying it to obtain the rGO-modified zinc foil.

3. The method for preparing the MOF-rGO composite modified zinc anode according to claim 2, characterized in that, In step S2 The ratio of zinc foil to rGO is 1 cm. 2 (3–6 mg); and / or The zinc foil has a thickness of 100–200 μm; and / or The dropping rate of the rGO dispersion is 0.02–0.05 mL / s; and / or The zinc foil is pulled upward at a speed of 3-7 mm / s.

4. The method for preparing the MOF-rGO composite modified zinc anode according to claim 2 or 3, characterized in that, In step S2 The drying temperature is 45–55°C, and the time is 0.5–1.5 h; and / or Before step S2, the zinc foil is polished in sequence using 2000-grit sandpaper and 10000-grit polishing plate.

5. The method for preparing the MOF-rGO composite modified zinc anode according to claim 1 or 2, characterized in that, In step S1 The weight ratio of the graphene oxide to the reducing agent is 1:(8-12); and / or The reducing agent includes one or more of ascorbic acid, hydrazine hydrate, and ethylenediamine; and / or The alcohol dispersant includes anhydrous ethanol and / or methanol; and / or The reduction reaction is carried out at a temperature of 60–70°C for a time of 35–45 minutes.

6. The method for preparing the MOF-rGO composite modified zinc anode according to claim 1 or 2, characterized in that, In step S1 The mass concentration of the rGO dispersion is 2.5–3.5 mg·mL. -1 ; and / or Step S1 further includes the following steps: mixing the graphene oxide and the reducing agent, and adjusting the pH of the solution to 8-12; and / or Step S1 further includes the following steps: first washing the reducing solution with water until the solution pH is 6.5-7.5, and then washing it 3-5 times with the alcohol dispersant to obtain the rGO.

7. The method for preparing the MOF-rGO composite modified zinc anode according to claim 1 or 2, characterized in that, In step S3 The zinc salt comprises Zn(Ac)₂·2H₂O and / or Zn(NO₃)₂·6H₂O; and / or The organic ligand includes one or more of 2-methylimidazolium, terephthalic acid, and trimesic acid; and / or The molar ratio of the zinc salt to the organic ligand is (0.15–0.3):1; and / or The ratio of the rGO-modified zinc foil to the organic ligand is 1 cm. 2 (0.04~0.06mmol).

8. The method for preparing the MOF-rGO composite modified zinc anode according to claim 1 or 2, characterized in that, In step S3 The first impregnation temperature is 20–30°C, and the time is 1–2 hours; and / or The second impregnation temperature is 20-30°C, and the time is 1-2 hours.

9. A MOF-rGO composite modified zinc anode, characterized in that, It is obtained using the preparation method according to any one of claims 1 to 8.

10. A zinc-based battery, characterized in that, Including the MOF-rGO composite modified zinc anode as described in claim 9.

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