Preparation method of zinc-based porous organic polymer coating and application of zinc-based porous organic polymer coating to protection of zinc negative electrode

Abstract

The invention belongs to the technical field of energy materials, and discloses a preparation method of a zinc-based porous organic polymer coating and application of the zinc-based porous organic polymer coating to protection of a zinc negative electrode. Reaction raw materials of the zinc-based porous organic polymer provided by the invention are cheap soluble zinc salt and pyromellitic acid, and the zinc-based porous organic polymer is obtained through a one-step solvothermal reaction. Polyvinylidene fluoride (PVDF) is adopted as a binder, and Zn-POPs is loaded on the surface of the zinc negative electrode in the modes of spin coating, blade coating, spray coating and the like. According to the Zn-POPs protective coating provided by the invention, the concentration distribution of zinc ions on an interface can be dynamically regulated and controlled by an unsaturated coordinate bond, and a dendrite-free zinc negative electrode is realized. Meanwhile, the coating can isolate direct contact between the electrolyte and the negative electrode, so that corrosion of the zinc negative electrode and generation of byproducts are reduced; when the coating is applied to a symmetric battery and a total battery, the battery can show low polarization voltage and stable cycle performance, the advantages of the coating are further highlighted, and subsequent large-scale industrial production can be expected.

Description

Technical Field

[0001] This invention belongs to the field of energy materials technology, and specifically discloses a method for preparing a zinc-based porous organic polymer coating and its application in protecting zinc anodes. Background Technology

[0002] As a novel high-energy-density battery, zinc-ion batteries have broad prospects for commercial application. Firstly, aqueous zinc-ion batteries possess high theoretical capacity, meeting the demands of large-scale energy storage and electric vehicles. Secondly, using zinc as the negative electrode and ZnSO4 solution as the electrolyte, aqueous zinc-ion batteries offer higher safety performance compared to traditional lithium-ion batteries. Furthermore, zinc is abundant and environmentally friendly, making the development of high-performance zinc-ion batteries a crucial measure to reduce energy storage and utilization costs. However, due to the direct contact between zinc metal and zinc sulfate electrolyte during electrochemical cycling, problems such as zinc dendrite growth, hydrogen evolution reaction, and surface passivation inevitably arise, severely impacting the battery's coulombic efficiency and cycle life. Therefore, controlling the interface between the zinc negative electrode and the electrolyte is key to stabilizing the zinc anode.

[0003] The protective layer coated on the negative electrode surface can form a physical protective layer between the zinc negative electrode and the electrolyte, effectively improving the stability of the zinc electrode interface and its long-cycle performance. The constructed artificial interface layer is mainly used to regulate the deposition behavior of zinc ions and suppress zinc dendrites; at the same time, the protective layer can also effectively avoid the occurrence of side reactions. However, at present, most coating materials face drawbacks such as cumbersome preparation processes and harsh operating conditions (usually requiring calcination or loading of other substances); the presence of the protective coating may also lead to problems such as low ionic conductivity and increased interfacial polarization, which has already impaired the practical performance of the battery. Summary of the Invention

[0004] To address the shortcomings mentioned in the background section, this invention provides a simple and effective method for synthesizing a new material, which is used as an interface protective layer for the anode of an aqueous zinc-ion battery. This invention aims to solve the problems of dendrite growth, hydrogen evolution reaction, and byproducts present in the zinc anode of aqueous zinc-ion batteries during cycling.

[0005] To achieve the above objectives, the present invention provides a method for preparing a zinc-based porous organic polymer coating. The technical solution of the present invention is as follows: Using pyromellitic acid and soluble zinc salt as reactants, zinc-based coordinated Zn-POPs were obtained through a one-step coordination reaction. Then, PVDF was used as a binder to load Zn-POPs nanoparticles onto the polished zinc anode surface, thus constructing a zinc anode with unsaturated zinc-based coordination polymers (Zn-POPs@Zn). The specific preparation steps include the following:

[0006] (1) Use zinc chloride or zinc nitrate as a soluble zinc metal salt. After accurate weighing, prepare a solution of a certain concentration.

[0007] (2) Mix the above solution with pyromellitic acid solution and carry out a one-step solvothermal reaction.

[0008] (3) After the reaction is complete, the nanoparticle product is obtained after washing and drying, and named: Zn-POPs.

[0009] Preferably, the soluble zinc metal salt in step (1) is prepared into a solution with a concentration of 0.1~5 mol / L using deionized water as a solvent. The molar ratio of zinc metal salt to pyromellitic acid is 1:(1~1.5).

[0010] Preferably, the solvothermal reaction temperature in step (2) is 80~120℃ and the reaction time is 12 h.

[0011] A zinc-based porous organic polymer coating is used to protect a zinc anode. The zinc metal is polished, and then the zinc-based porous organic polymer described in claim 4 is coated on one side of the polished zinc metal as a protective coating to obtain a Zn-POPs@Zn anode.

[0012] Preferably, the polishing process involves using 800, 1000, and 3000 grit sandpaper in successive stages; after polishing, the surface is cleaned with ethanol and dried in a vacuum oven for later use.

[0013] Preferably, the coating process includes the following steps: (1) The Zn-POPs prepared according to claim 4 are mixed and stirred with a binder until they are homogeneous; the mixture is coated onto the surface of the zinc anode by spin coating, scraping or spraying. (2) Drying and protecting the coating. The drying and curing conditions are vacuum or atmospheric environment, temperature is 60~80℃, time is 6~12h, and zinc anode Zn-POPs@Zn protected by zinc-based porous organic polymer is obtained.

[0014] Preferably, the dry film thickness of the Zn-POPs protective layer is 30~100 μm.

[0015] Preferably, the adhesive is PVDF, and the adhesive accounts for 10% of the total mass.

[0016] An aqueous zinc-ion battery is characterized by comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode is a Mn-doped V2O5 positive electrode (MVO), the negative electrode is a Zn-POPs@Zn negative electrode prepared in the above steps, the electrolyte is a 2 mol / L ZnSO4 solution, and the separator is a GF / A glass fiber filter membrane.

[0017] This invention prepares the coating material required for the zinc anode of an aqueous zinc-ion battery through a one-step solvothermal reaction. This method is simple, efficient and energy-efficient, which is conducive to large-scale industrial production.

[0018] Furthermore, a Zn-POPs coating material with unsaturated coordination bonds exhibits an irregular nanoparticle morphology under a scanning electron microscope, and it is in an aggregated state. The microscopic chemical structure of Zn-POPs is prepared by unsaturated coordination crystallization of zinc ions and pyromellitic acid anions using soluble zinc metal salts as the zinc source and pyromellitic acid with strong coordination ability as the ligand. Its unsaturated sites are coordination bonds, which can dynamically regulate the concentration distribution of zinc ions at the interface; simultaneously, the zinc-rich environment can also promote the migration kinetics of zinc ions.

[0019] Furthermore, a zinc anode protected by a Zn-POPs coating material physically isolates the zinc substrate from direct contact with water, thereby inhibiting the hydrogen evolution reaction and the formation of byproducts. Unsaturated coordinated Zn-POPs enhance the ion conductivity of the coating, dynamically regulate the zinc ion flow at the interface, and homogenize the zinc ion flux, achieving a dendrite-free zinc anode.

[0020] Furthermore, an aqueous zinc-ion symmetric battery includes a positive electrode, a separator, a negative electrode, and an electrolyte, wherein both the positive and negative electrodes are Zn-POPs@Zn. An aqueous zinc-ion full battery includes a positive electrode, a separator, a negative electrode, and an electrolyte, wherein the negative electrode is Zn-POPs@Zn, and the positive electrode is Mn-doped V₂O₅ (MVO). MVO is prepared by uniformly mixing MVO, acetylene black, and PTFE emulsion in a 6:3:1 mass ratio using acetylene black as a conductive agent and PTFE (polytetrafluoroethylene) as a binder, and then coating the mixture onto titanium foil to obtain the positive electrode sheet.

[0021] The beneficial effects of this invention are as follows: This invention utilizes inexpensive reagents as reactants to prepare a coating material suitable for zinc anode protection in aqueous zinc-ion batteries via a simple coordination reaction and solvothermal method. The provided coating material possesses abundant unsaturated coordination bonds, allowing for dynamic control of the zinc ion concentration distribution at the interface, achieving a dendrite-free zinc anode. Simultaneously, the unsaturated coordination structure of the coating material contains Zn²⁺ and zinc-loving sites, which facilitates high redox kinetics and promotes zinc ion desolvation, effectively improving the overall battery performance. Furthermore, the provided coating material can also physically isolate the zinc substrate from direct contact with active water, inhibiting hydrogen evolution reaction and the formation of byproducts. The anode protection material provided by this invention is simple, economical, and effective to prepare, making it suitable for large-scale industrial production. Attached Figure Description

[0022] Figure 1 This is a SEM image of Zn-POPs provided in Embodiment 1 of the present invention; Figure 2 This is the XRD pattern of Zn-POPs provided in Embodiment 1 of the present invention; Figure 3 This is the infrared spectrum of Zn-POPs provided in Embodiment 1 of the present invention; Figure 4 This is a thermogravimetric curve of Zn-POPs provided in Embodiment 1 of the present invention; Figure 5 This is the zeta potential diagram of Zn-POPs provided in Embodiment 1 of the present invention; Figure 6 This is a SEM image of Zn-POPs@Zn provided in Embodiment 1 of the present invention; Figure 7 This is the XRD pattern of Zn-POPs@Zn provided in Embodiment 1 of the present invention; Figure 8 These are time-current curves of Zn-POPs@Zn and bare zinc anodes in the comparative example provided in Embodiment 1 of the present invention; Figure 9 These are Tafel curves of Zn-POPs@Zn provided in Embodiment 1 of the present invention and bare zinc anodes in the comparative example; Figure 10 These are in-situ optical microscope images of Zn-POPs@Zn and bare zinc negative electrode electroplating in Example 1 of this invention and in the comparative example. Figure 11 These are the impedance diagrams and fitted activation energy diagrams of the Zn-POPs@Zn and the bare zinc anode in the comparative example provided in Example 1 of this invention at different temperatures; Figure 12 These are the ionic conductivity test graphs of Zn-POPs@Zn and bare zinc anodes in the comparative example provided in Embodiment 1 of the present invention on GF / A glass fiber filter membranes; Figure 13 This is a graph showing the long-cycle stability test results of the Zn-POPs@Zn / / Zn-POPs@Zn symmetric cell provided in Embodiment 1 of the present invention and the Bare@Zn / / Bare@Zn symmetric cell in the comparative example; Figure 14 These are the negative electrode SEM images of the Zn-POPs@Zn / / Zn-POPs@Zn symmetric cell provided in Embodiment 1 of the present invention and the Bare@Zn / / Bare@Zn symmetric cell in the comparative example before and after 100 h of cycling. Figure 15 This is a SEM image of MVO provided in the comparative example of this invention; Figure 16These are the CV curves of the Zn-POPs@Zn / / MVO full cell provided in Embodiment 1 of the present invention and the Bare@Zn / / MVO full cell in the comparative example; Figure 17 These are the long-cycle stability test results of the Zn-POPs@Zn / / MVO full cell provided in Embodiment 1 of the present invention and the Bare@Zn / / MVO full cell in the comparative example. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, specific embodiments are provided below to explain and illustrate the invention. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0024] Comparative Example (1) Preparation of bare zinc negative electrode Zinc foil was polished step by step with 800, 1000 and 3000 grit sandpaper. After being cleaned with ethanol and dried under vacuum at 60°C, the zinc foil was cut into small round pieces with a diameter of 14 mm using a slicing machine to obtain bare zinc negative electrodes.

[0025] (2) Preparation of MVO positive electrode MVO, acetylene black, and PTFE emulsion were weighed according to a mass ratio of 6:3:1, and the mixture was ground into a homogeneous state using a mortar and pestle. The mixture was then coated onto a titanium foil current collector using a 70 mm scraper, and after drying, a positive electrode sheet was obtained with a loading of ~2 mg·cm⁻¹. -2 (MVO).

[0026] (3) Assembly of Bare@Zn / / Bare@Zn batteries Bare@Zn electrodes are positive and negative electrodes, GF / A glass fiber filter membrane is used as the separator, 2 mol / L ZnSO4 solution is used as the electrolyte, and symmetrical cells are assembled using CR2032 button cell cases.

[0027] (4) Assembly of Bare@Zn / / MVO full battery The Bare@Zn electrode is the negative electrode, the MVO electrode is the positive electrode, the GF / A glass fiber filter membrane is the separator, the 2 mol / L ZnSO4 solution is the electrolyte, and the full cell is equipped with a CR2032 coin cell case.

[0028] (5) Electrochemical behavior test The time required to achieve stable three-dimensional diffusion was analyzed using the chronoamperometry (CA) method. Figure 8 Tafel curve analysis of electrode corrosion resistance Figure 9 In-situ optical microscopy observation of dendrite growth during electroplating process Figure 10); Deposition activation energy test for the desolvation ability of zinc hexahydrate ions ( Figure 11 ); Ion conductivity is used to detect the transport capacity of ions ( Figure 12 ); Battery cyclic voltammetry ( Figure 16 Observe the redox kinetics of the full cell.

[0029] (6) Battery performance test Test subject: Bare@Zn / / Bare@Zn symmetric cell. Tested at 25°C with a current of 3 mA·cm⁻¹. -2 Current density, 1 mAh·cm -2 Cyclic testing was conducted on the area capacity to observe the battery cycle life. Figure 13 After the cycle test, the battery was disassembled to observe the accumulated byproducts on the negative electrode surface. Figure 14 ).

[0030] Test subject: Bare@Zn / / MVO full cell. Tested at 25°C with 1 A·g -1 Cyclic testing was performed on the current density. Figure 17 ), observe the capacity decay of the battery.

[0031] Example 1 Example 1 of this invention describes the preparation and application of a Zn-POPs coating, comprising the following steps: (1) Preparation of Zn-POPs 0.13 g of ZnCl2 and 0.38 g of pyromellitic acid were weighed and dissolved in 30 mL of deionized water. After both solutes were completely dissolved, the mixture was stirred for 30 min. The mixture was then transferred to a reaction vessel and reacted at 120 °C for 12 h. After the reaction was completed, the product was washed twice with deionized water and then with ethanol, and dried under vacuum at 80 °C for 10 h to obtain Zn-POPs material.

[0032] (2) Polish the zinc metal by using 800, 1000 and 3000 grit sandpaper for step-by-step processing. After polishing, clean the surface with ethanol and dry it in a vacuum oven.

[0033] (3) Preparation of Zn-POPs@Zn negative electrode Zn-POPs material and PVDF were ground to a homogeneous state at a mass ratio of 9:1, and then an appropriate amount of N-methylpyrrolidone (NMP) was added to form a slurry. 30 μL of the slurry was pipetted and uniformly loaded onto the surface of a bare zinc anode using a drop-coating method. The electrode was then transferred to a vacuum oven at 60 °C and dried for 12 h to prepare a Zn-POPs@Zn anode with a protective coating.

[0034] (4) Zn-POPs@Zn / / Zn-POPs@Zn battery assembly Zn-POPs@Zn electrodes were used as positive and negative electrodes, respectively. A GF / A glass fiber filter membrane was used as the separator, and a 2 mol / L ZnSO4 solution was used as the electrolyte. A symmetrical cell was assembled using a CR2032 coin cell case.

[0035] (5) Assembly of Zn-POPs@Zn / / MVO full cells The Zn-POPs@Zn electrode is used as the negative electrode, the MVO electrode as the positive electrode, the GF / A glass fiber filter membrane as the separator, and the 2mol / L ZnSO4 solution as the electrolyte. The full cell is equipped with a CR2032 coin cell case.

[0036] (6) Electrochemical behavior test The time required for zinc ions to achieve stable three-dimensional diffusion in a symmetrical cell was analyzed using the chronoamperometry (CA) method. Figure 8 Tafel curve analysis of electrode corrosion resistance Figure 9 In-situ optical microscopy observation of dendrite growth during electroplating process Figure 10 ); Deposition activation energy test for the desolvation ability of zinc hexahydrate ions ( Figure 11 ); Ionic conductivity reflects the transport capacity of zinc ions. Figure 12 ); Battery cyclic voltammetry ( Figure 16 Observe the redox kinetics of the full cell.

[0037] (7) Battery performance test Test subject: Zn-POPs@Zn / / Zn-POPs@Zn symmetric cells. Tested at 25°C with a current of 3 mA·cm⁻¹. -2 Current density, 1 mAh·cm -2 Cyclic testing was conducted on the area capacity to observe the battery cycle life. Figure 13 After the cycle test, disassemble the battery to observe whether the coating is cracked or damaged. Figure 14 ).

[0038] Test subject: Zn-POPs@Zn / / MVO full cell. Tested at 25°C with 1 A·g -1 Current density was subjected to cyclic testing. Figure 17 ), observe the capacity decay of the battery.

[0039] Example 2 Example 2 of this invention describes the preparation and application of a Zn-POPs coating, comprising the following steps: (1) Preparation of Zn-POPs 0.29 g of Zn(NO3)2·6H2O and 0.38 g of pyromellitic acid were weighed and dissolved in 30 mL of deionized water. After both solutes were completely dissolved, the mixture was stirred for 2 h. The mixture was then transferred to a reaction vessel and reacted at 80 °C for 12 h. After the reaction was completed, the product was washed twice with deionized water and then with ethanol, and dried under vacuum at 80 °C for 10 h to obtain Zn-POPs material.

[0040] (2) Polish the zinc metal by using 800, 1000 and 3000 grit sandpaper for step-by-step processing. After polishing, clean the surface with ethanol and dry it in a vacuum oven.

[0041] (3) Preparation of Zn-POPs@Zn negative electrode Zn-POPs material and PVDF were ground to a homogeneous state at a mass ratio of 9:1, and then an appropriate amount of NMP was added to form a slurry. 30 μL of the slurry was pipetted and uniformly loaded onto the surface of a bare zinc anode using a drop-coating method. The electrode was then transferred to an 80°C vacuum oven for drying for 6 h, thus preparing a Zn-POPs@Zn anode with a protective coating.

[0042] (4) Zn-POPs@Zn / / Zn-POPs@Zn battery assembly Zn-POPs@Zn electrodes were used as positive and negative electrodes, respectively. A GF / A glass fiber filter membrane was used as the separator, and a 2 mol / L ZnSO4 solution was used as the electrolyte. A symmetrical cell was assembled using a CR2032 coin cell case.

[0043] (5) Assembly of Zn-POPs@Zn / / MVO full cells The Zn-POPs@Zn electrode is used as the negative electrode, the MVO electrode as the positive electrode, the GF / A glass fiber filter membrane as the separator, and the 2mol / L ZnSO4 solution as the electrolyte. The full cell is equipped with a CR2032 coin cell case.

[0044] (6) Electrochemical behavior test The time required for zinc ions to achieve stable three-dimensional diffusion was analyzed using chronoamperometry (CA); the corrosion resistance of the electrode was analyzed using Tafel curves; dendrite growth during the electroplating process was observed using in-situ optical microscopy; the desolvation capacity of zinc hexahydrate ions was tested using deposition activation energy; ionic conductivity reflects the ion transport capacity; and the redox kinetics of the full cell were observed using cyclic voltammetry.

[0045] (7) Battery performance test Test subject: Zn-POPs@Zn / / Zn-POPs@Zn symmetric cells. Tested at 25°C with a current of 3 mA·cm⁻¹. -2 Current density, 1 mAh·cm-2 Cyclic testing was conducted on the area capacity to observe the battery's cycle life. After the cycle test, the battery was disassembled to inspect whether the coating was cracked or damaged.

[0046] Test subject: Zn-POPs@Zn / / MVO full cell. Tested at 25°C with 1 A·g -1 Cyclic testing was conducted using current density to observe the battery's capacity decay.

[0047] Results analysis: observe Figure 1 It can be seen that Zn-POPs are irregular nanoparticles and are in an aggregated state.

[0048] observe Figure 2 It can be seen that the material has a relatively standard crystal form.

[0049] observe Figure 3 As can be seen, the infrared spectrum shows obvious -OH peaks and uncoordinated anions, indicating that there is an unsaturated coordination process in the reaction.

[0050] observe Figure 4 It can be seen that the thermogravimetric process of Zn-POPs is divided into three stages.

[0051] observe Figure 5 It is known that the zeta potential of Zn-POPs materials is negative, which is attributed to the uncoordinated anions.

[0052] observe Figure 6 It can be seen that the Zn-POPs material is uniformly coated on the zinc substrate, forming a uniform and dense protective layer.

[0053] observe Figure 7 It can be seen that the XRD diffraction pattern of the Zn-POPs@Zn electrode prepared by drop coating corresponds to the peak positions of the standard card of metallic zinc and Zn-POPs, indicating that the presence of binder has no significant effect on the crystal structure of Zn-POPs.

[0054] observe Figure 8 It was observed that the current density of the bare zinc anode continuously increased within 200 s, with an overpotential of -150 mV. This indicates rampant disordered two-dimensional diffusion, leading to nucleation aggregation at preferred nucleation sites. The initial protrusions further exacerbated the "tip effect," resulting in uneven zinc deposition. In contrast, the coating on the Zn-POPs@Zn anode surface can restrict disordered two-dimensional diffusion on the anode surface, inducing a dendrite-free zinc anode.

[0055] observe Figure 9It can be seen that, compared with bare zinc anode, Zn-POPs@Zn anode has a lower corrosion voltage and a significantly increased corrosion resistance current. This indicates that Zn-POPs@Zn anode has excellent corrosion resistance and can isolate the electrolyte from direct contact with water, thereby inhibiting the hydrogen evolution and oxygen evolution reactions involving active water.

[0056] Figure 10 Reflected at 10 mA·cm -2 Dendrite growth during electroplating at current density. Observation. Figure 10 It can be seen that the Zn-POPs@Zn anode maintains a smooth surface throughout the entire electroplating process (20 min).

[0057] observe Figure 11 It can be seen that the coating of the negative electrode is conducive to the desolvation process of zinc hexahydrate ions, resulting in a lower zinc deposition activation energy for the Zn-POPs@Zn negative electrode.

[0058] observe Figure 12 It is evident that the Zn-POPs coating exhibits superior ionic conductivity compared to the GF / A separator. This indicates that the Zn-POPs coating effectively isolates water molecules in the zinc sulfate electrolyte from contact with the negative electrode while simultaneously enabling rapid zinc ion transfer without affecting zinc ion migration. The synergistic effect of the Zn-POPs coating in this invention, combining the advantages of the Zn-POPs@Zn negative electrode, can extend the lifespan of the Zn-POPs@Zn / / Zn-POPs@Zn symmetric battery by approximately 10 times. Figure 13 At the same time, the capacity retention rate of the entire battery can also be significantly improved. Figure 17 This confirms the effectiveness of the Zn-POPs coating.

[0059] Figure 14 This shows the SEM images of the negative electrode of the symmetrical battery before and after 100 hours of cycling. (Observation) Figure 14 It can be seen that the Zn-POPs@Zn anode did not experience coating peeling or dendrite growth after 100 h of cycling, indicating that the Zn-POPs coating has excellent stability.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a zinc-based porous organic polymer coating, characterized in that, Zn-POPs nanoparticles were prepared by a one-step solvothermal method to generate crystallized products through unsaturated coordination reaction. These particles have abundant unsaturated coordination bonds and exhibit a negative surface charge.

2. The method for preparing the zinc-based porous organic polymer coating according to claim 1, characterized in that, Includes the following steps: (1) Select zinc chloride or zinc nitrate as soluble zinc metal salts, and after accurate weighing, prepare a solution of a certain concentration. (2) The above solution is mixed with pyromellitic acid solution and a coordination reaction is carried out by a one-step solvothermal method; (3) After the reaction is complete, the nanoparticle product is obtained after washing and drying, and named Zn-POPs.

3. The method for preparing the zinc-based porous organic polymer coating according to claim 2, characterized in that, The soluble zinc metal salt described in step (1) is prepared into a solution with a concentration of 0.1~5 mol / L using deionized water as a solvent. The molar ratio of zinc metal salt to pyromellitic acid is 1:(1~1.5).

4. The method for preparing the zinc-based porous organic polymer coating according to claim 2, characterized in that, The reaction temperature of the solvothermal method in step (2) is 80~120℃, and the reaction time is 12 h.

5. The application of the zinc-based porous organic polymer coating of claim 4 for the protection of zinc anodes, characterized in that, The zinc metal is polished, and then the zinc-based porous organic polymer described in claim 4 is coated on one side of the polished zinc metal as a protective coating to obtain Zn-POPs@Zn anode.

6. The application of the zinc-based porous organic polymer coating for protecting zinc anodes according to claim 5, characterized in that, The polishing process involves using 800, 1000, and 3000 grit sandpaper in successive stages. After polishing, the surface is cleaned with ethanol and dried in a vacuum oven until ready for use.

7. The application of the zinc-based porous organic polymer coating for protecting zinc anodes according to claim 5, characterized in that, The coating process includes the following steps: (1) The Zn-POPs prepared according to claim 4 are mixed and stirred with a binder until they are homogeneous; the mixture is coated onto the surface of the zinc anode by spin coating, scraping or spraying. (2) Drying and protecting the coating. The drying and curing conditions are vacuum or atmospheric environment, temperature is 60~80℃, time is 6~12 h, and zinc anode Zn-POPs@Zn protected by zinc-based porous organic polymer is obtained.

8. The application of the zinc-based porous organic polymer coating for protecting zinc anodes according to claim 5, characterized in that, The dry film thickness of the Zn-POPs protective layer is 30~100 μm.

9. The application of the zinc-based porous organic polymer coating according to claim 7 for the protection of zinc anodes, characterized in that, The adhesive is preferably PVDF, and the adhesive accounts for 10% of the total mass.

10. An aqueous zinc-ion battery, characterized in that, It includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode is a Mn-doped V2O5 positive electrode (MVO), the negative electrode is the Zn-POPs@Zn negative electrode prepared according to claim 8, the electrolyte is a 2 mol / L ZnSO4 solution, and the separator is a GF / A glass fiber filter membrane.

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