A method for constructing a zinc negative electrode interface protection layer in situ based on gel slow-release technology

Abstract

The application discloses a method for in-situ construction of a zinc negative electrode interface protection layer based on a gel slow-release technology, and the method comprises the following steps: uniformly coating a gel solution containing a water gel polymerization and slow-release component on the surface of a zinc foil, and finally obtaining a zinc foil with an interface protection layer formed, wherein the method controls the reaction rate and reaction uniformity of the slow-release component and zinc reaction for forming an interface layer through a gel network, and compared with the defects that the polishing or pickling means in the prior art can only temporarily remove a passivation layer and a new passivation layer is formed in the battery cycle process, the scheme can effectively remove the oxidation passivation layer on the surface of the zinc metal and prevent the formation of a new passivation layer, and has a significant advantage.

Description

Technical Field

[0001] This invention belongs to the field of zinc battery anode processing technology, specifically involving a method for in-situ construction of a zinc anode interface protective layer based on gel slow-release technology. Background Technology

[0002] A significant advantage of aqueous zinc batteries is the direct use of zinc metal as the negative electrode. Zinc metal negative electrodes offer advantages over ion-hosted negative electrodes due to their high energy density, ease of recycling, and lower processing requirements. However, uneven zinc deposition can lead to dendrite formation during cycling, which can ultimately cause soft short circuits or even direct battery failure, affecting battery stability and lifespan.

[0003] Zinc deposition is influenced by a variety of factors. Studies involve electrolyte composition and solvent structure, electrochemical parameters such as current density, and environmental factors such as temperature and pressure. Most importantly, the properties of the substrate play a crucial role. The zinc surface should have a smooth morphology to avoid the "point effect" and should promote rapid diffusion of zinc ions to prevent dendrite formation caused by localized ion enrichment. For zinc metal stored in air, it is necessary to remove the intrinsic oxide layer, as these passivation components hinder zinc ion transport, leading to uneven zinc deposition. Furthermore, zinc deposition preferentially occurs at sites of passivation layer damage, and localized zinc deposition leads to dendrite growth. Studies have shown that physically polished or acid-etched zinc metal performs better than untreated zinc.

[0004] Physical polishing involves grinding the surface of commercial zinc foil using sandpaper or other mechanical methods. However, the ground surface produces a lot of texture. At the microscale of zinc ion deposition, the uneven morphology makes dendrite growth easy, increasing the specific surface area of ​​zinc, introducing a lot of defects, and causing side reactions to intensify in subsequent cycles. Moreover, the grinding process only temporarily removes the passivation layer, and the surface is prone to re-oxidation after being exposed to the atmosphere for a period of time.

[0005] Chemical acid etching involves immersing zinc foil in an acidic solution (such as phosphoric acid or sulfuric acid) to remove the passivation layer and expose the active zinc surface through acid corrosion. However, the acid etching process is too fast, and there is a preferred orientation of the reaction crystal planes, which results in a large number of pores after the reaction, making it difficult to control the surface morphology. A large number of bubbles generated during acid etching can interfere with the surface reaction, causing local unevenness. Furthermore, acid etching increases the surface area of ​​zinc, which may exacerbate side reactions (such as hydrogen evolution reaction).

[0006] In other words, existing polishing or acid pickling methods can only temporarily remove the passivation layer, and new passivation layers, such as zinc oxide and zinc hydroxysulfate, will form during battery cycling. Therefore, removing the oxide passivation layer on the zinc metal surface and preventing the formation of new passivation layers is crucial and challenging. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0011] The hydrogel polymer is dissolved in deionized water, heated and stirred until the hydrogel polymer is completely dissolved, cooled to room temperature, and then a slow-release component is added and stirred until uniform to obtain a gel solution. The slow-release component is an acid or a substance that can form a zinc-like protective layer through a chemical conversion reaction.

[0012] The gel solution is uniformly coated onto a clean zinc foil surface, ensuring complete and uniform gel coverage. The coated zinc foil is then allowed to stand at room temperature to react, forming a uniform pre-treated coating on the zinc substrate.

[0013] Scrape off any excess gel on the pre-treated coating that is not in contact with the zinc substrate, rinse with deionized water to remove any remaining gel, and finally rinse the zinc foil with anhydrous ethanol. Allow it to air dry at room temperature to obtain the zinc foil that forms the interface protective layer.

[0014] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, wherein: the hydrogel polymer includes one of polyvinyl alcohol, alginate, chitosan, gelatin, and polyethylene glycol.

[0015] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, the heating and stirring temperature is 60-95℃ and the time is 2-4h.

[0016] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, the heating and stirring temperature is 60-95℃ and the time is 2-4h.

[0017] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, wherein the mass concentration of the hydrogel polymer in the gel solution is 5-20%.

[0018] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, wherein: the acid includes one of phosphoric acid, hydrochloric acid, boric acid, formic acid, acetic acid, citric acid, and tartaric acid.

[0019] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, wherein: the substance that can form a zinc-like protective layer through chemical conversion reaction includes one of chromates, fluorides, and phosphates.

[0020] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, wherein the concentration of acid in the gel solution is 0.1-3M.

[0021] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, wherein the thickness of the gel coated on the zinc foil surface is 0.1 to 1 cm.

[0022] As a preferred embodiment of the method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology according to the present invention, the standing reaction time is 1 to 4 hours.

[0023] Another objective of this invention is to provide a method for preparing zinc foil by in-situ construction of a zinc anode interface protective layer based on gel slow-release technology, which is then used as a zinc anode in the preparation of zinc batteries.

[0024] Beneficial effects of this invention:

[0025] The method of constructing a zinc anode interface protective layer in situ based on gel slow-release technology can eliminate surface defects introduced by physical polishing, overcome the problems of excessively fast reaction and uneven surface corrosion in chemical acid etching, provide a uniform and stable zinc anode surface, and inhibit dendrite growth. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0027] Figure 1 A flowchart illustrating the in-situ construction of a zinc anode interface protective layer based on gel-release technology (GSR);

[0028] Figure 2 This is a morphology diagram of the gel-release pretreated coating on the zinc foil after Example 1.

[0029] Figure 3 The images show the spectroscopic characterization of the zinc foil after treatment and the untreated zinc foil in Example 1.

[0030] Figure 4 This is a cross-sectional EDS elemental distribution diagram of the zinc foil after processing in Example 1.

[0031] Figure 5 This is a schematic diagram of the process for treating zinc foil using traditional physical polishing methods, as shown in Comparative Example 1.

[0032] Figure 6 This is a schematic diagram of the process for treating zinc foil using a traditional chemical acid etching method, which serves as Comparative Example 2.

[0033] Figure 7 The images show scanning electron microscope (SEM) images of zinc foil after treatment in Example 1 and Comparative Examples 1 and 2, as well as untreated zinc foil.

[0034] Figure 8 SEM images and digital photographs of the zinc electrode after cycling (illustration).

[0035] Figure 9 For zinc at a current density of 1 mA cm -2 In-situ optical microscope cross-sectional image of the deposition process under the given conditions for 1 hour.

[0036] Figure 10 LSV curves of different zinc anodes in 0.5M Na2SO4 electrolyte.

[0037] Figure 11 Long-cycle performance of zinc symmetric batteries with different zinc anodes.

[0038] Figure 12 SEM images and digital photographs of zinc surfaces after different acid treatments in Example 2 and Comparative Example 3.

[0039] Figure 13 The results show the long-cycle stability test results of symmetrical batteries assembled from zinc foils obtained after different acid treatments in Example 2 and Comparative Example 3.

[0040] Figure 14 SEM images of the zinc foil surface and cross-section after 9 hours of processing of the product in Example 3.

[0041] Figure 15 The image shows SEM images of the zinc surface after different phosphoric acid concentrations and treatment times in Example 4. Detailed Implementation

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0044] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0045] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0046] Example 1

[0047] Reference Figure 1 This embodiment provides a method for in-situ construction of a zinc anode interface protective layer based on gel-release technology (GSR), specifically:

[0048] 1) Clean the zinc foil with anhydrous ethanol to remove surface dust and oil, ensuring a clean substrate and obtaining clean zinc foil;

[0049] 2) Polyvinyl alcohol (PVA) is mixed with deionized water to obtain a PVA aqueous solution with a PVA mass fraction of 15%. The solution is heated to 90°C and stirred for 2 hours until the PVA is completely dissolved. After cooling to room temperature, 1M phosphoric acid (slow-release component) is added and stirred for more than 24 hours until homogeneous to obtain a gel solution.

[0050] 3) Coat the clean zinc foil surface evenly with the gel solution, and adjust the thickness of the gel coating to 0.5 cm using a scraper to ensure that the gel covers the entire surface and the thickness is uniform. Let the coated zinc foil stand at room temperature for 1 hour to allow the slow-release components to react slowly with the zinc substrate and form a uniform pre-treated coating on the zinc substrate.

[0051] 4) Use a scraper to remove excess gel from the pre-treated coating that is not in contact with the zinc substrate, rinse with deionized water to remove residual gel, and finally rinse the zinc foil with anhydrous ethanol. Let it air dry at room temperature (humidity ≤60%) to obtain zinc foil (GSR-Zn) that forms an interface protective layer.

[0052] Figure 2 The image shows the morphology of the gel-release pretreated coating on the zinc foil after treatment in Example 1, where (a) is a scanning electron microscope image, (b) is a 3D morphology reconstructed by atomic force microscopy, and (c) is a cross-sectional image. Figure 3The spectroscopic characterization of zinc foil treated and untreated in Example 1 is shown, where (a) is the X-ray photoelectron spectroscopy P2p spectrum and (b) is the Raman spectrum. Figure 4 The following are cross-sectional EDS elemental distribution maps of the zinc foil after processing in Example 1, where (a) is a cross-sectional image; (b) is an O elemental distribution map; (c) is a P elemental distribution map; and (d) is a Zn elemental distribution map.

[0053] X-ray photoelectron spectroscopy (XPS) P2p spectra further confirmed the presence of phosphorus signals on the zinc surface treated with gel-release in this embodiment. This demonstrates that gel-release is not simply acid etching, but rather promotes the formation of a solid interface layer rich in zinc phosphate.

[0054] Raman spectroscopy revealed asymmetric vibrational peaks of carbonate ions on the untreated zinc surface. After gel-release pretreatment, vibrational peaks of phosphate ions and CH bonds appeared on the surface. This demonstrates that the gel-release pretreatment coating can effectively remove the surface passivation layer and form a composite coating of inorganic zinc phosphate and organic polyvinyl alcohol.

[0055] EDS analysis of the cross-section confirmed the elemental distribution, clearly showing that the granular coating region is composed of Zn, P, and O. The spaces between the zinc phosphate particles are filled with O. This confirms that the coating is a composite coating composed of zinc phosphate particles and polyvinyl alcohol organic components.

[0056] Comparative Example 1

[0057] Reference Figure 5 This comparative example uses a traditional physical polishing method (Polished Zn) to treat zinc foil, specifically:

[0058] 1) First, polish the clean zinc foil with 3000-grit metallographic sandpaper, repeating the polishing process 60 times.

[0059] 2) Rinse the zinc foil with anhydrous ethanol and air dry at room temperature (humidity ≤60%) to obtain the zinc foil treated in this comparative example.

[0060] Comparative Example 2

[0061] Reference Figure 6 This comparative example uses a traditional chemical acid etching method (Etched Zn) to treat zinc foil, specifically:

[0062] 1) Clean the zinc foil with anhydrous ethanol to remove surface dust and oil, ensuring a clean substrate and obtaining clean zinc foil;

[0063] 2) Soak the clean zinc foil in a 1M phosphoric acid solution, let it stand for 1 hour, rinse the zinc foil with deionized water and anhydrous ethanol respectively, and air dry it at room temperature (humidity ≤60%) to obtain the zinc foil of this comparative example.

[0064] Figure 7 The images show scanning electron microscope (SEM) images of zinc foil treated in Example 1 and Comparative Examples 1 and 2, as well as untreated zinc foil, where (a, b) represents untreated zinc; (c, d) represents physically polished zinc; (e, f) represents acid-etched zinc; and (g, h) represents gel-release treated zinc.

[0065] from Figure 7 It can be seen that, compared with other treatment methods, gel slow-release treatment can uniformly and gently remove the passivation layer on the zinc surface, maintain the smoothness of the microscopic surface, and obtain a uniform and thin zinc phosphate-dominated passivation layer on the zinc surface. This is because the formed gel network has uniform reaction sites, which limits the reaction rate.

[0066] Electrochemical testing

[0067] Zinc is punched into 12 mm diameter discs. Using a CR2025 battery as a mold, the specific battery assembly sequence is as follows: First, the negative electrode shell is placed at the bottom of the mold, then zinc sheet, glass fiber membrane, 2M ZnSO4 electrolyte, zinc sheet are added in sequence, followed by gasket and spring sheet, and finally the positive electrode shell is placed and sealed to obtain the battery. The long cycle performance test of the battery is completed on the Blue Battery Tester (CT3001A).

[0068] Figure 8 SEM images of the zinc electrode after cycling are shown, where (a) is untreated zinc (Raw Zn) and (b) is GSR-treated zinc. The inset is a macro photograph of the electrode. The SEM images clearly show the contrast between the two after 100 cycles. In the microscopic region, untreated zinc tends to form indeterminate and randomly distributed zinc dendrites due to the presence of a passivation layer. The inset shows the deposition in the macroscopic region, visually indicating that some areas have excessive zinc deposition, while the rest remain flat. In contrast, after removing the passivation layer, GSR-treated zinc also forms a composite coating with a high zinc ion diffusion coefficient, which effectively modulates zinc deposition and maintains more uniform reactivity in the electrode region.

[0069] Figure 9 For zinc at a current density of 1 mA cm -2 In-situ optical micrographs of cross-sectional zinc obtained during the 1-hour deposition process under the specified conditions, where (a) shows untreated zinc and (b) shows GSR-treated zinc. Figure 9It can be seen that zinc dendrite growth is evident in untreated zinc. Due to the presence of the passivation layer, untreated zinc leads to localized zinc deposition and dendrite growth. Furthermore, untreated zinc preferentially deposits on the cross-section because the cut cross-section represents newly exposed active sites. Simultaneously, bubbles continuously precipitate on the surface of untreated zinc during the test, indicating a significant HER reaction on the electrode surface. In stark contrast, GSR-treated zinc, due to the zinc phosphate-dominated interface layer effectively regulating zinc deposition, exhibits a relatively uniform morphology during the zinc deposition process.

[0070] The onset potential of the hydrogen evolution reaction (HER) was determined by linear sweep voltammetry (LSV) for zinc samples from Example 1 and Comparative Examples 1 and 2, which underwent different treatments. The tests were performed in 0.5 M Na₂SO₄ to avoid interference from Zn deposition on the HER test. The results are as follows: Figure 10 , Figure 11 As shown.

[0071] from Figure 10 The LSV curves show that the HER reaction initiation potential on the GSR-Zn surface is significantly delayed compared to that on Raw Zn, indicating that GSR-treated zinc can achieve corrosion protection and inhibit the occurrence of HER side reactions.

[0072] Figure 11 For the long-cycle performance of zinc symmetric batteries, the current density and capacity are 0.5 mA cm⁻¹. -2 and 0.5mAhcm -2 In long-cycle testing, untreated zinc experienced short circuits due to localized dendrite growth piercing the separator, leading to battery failure at 136 hours. Polished zinc showed a cycle life of 109 hours, a decrease compared to untreated zinc, due to the intense hydrogen evolution reaction. Etched zinc showed improved cycle life compared to untreated zinc because acid etching created numerous pores, providing space for zinc deposition. However, it ultimately failed around 1250 hours due to uneven zinc deposition and side reactions. GSR-treated zinc, through uniform removal of the surface passivation layer and the construction of an artificial interface layer to achieve rapid zinc ion conduction, exhibited the longest cycle life, reaching 5200 hours.

[0073] Example 2

[0074] This embodiment uses different types of sustained-release components for comparative experiments. Specifically, the difference from Example 1 is that the phosphoric acid in step 2) is adjusted to be sulfuric acid (H2SO4), benzenesulfonic acid (BA), trifluoromethanesulfonic acid (HOTf), and nitric acid (HNO3).

[0075] The remaining steps and processes are all the same as in Example 1, except for the zinc foil treated with different slow-release components in this example.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 2 is that the acid etching solutions were adjusted to be sulfuric acid (H2SO4), benzenesulfonic acid (BA), trifluoromethanesulfonic acid (HOTf), and nitric acid (HNO3).

[0078] The remaining steps and processes are the same as those in Comparative Example 2, which shows zinc foil etched with different acids in this comparative example.

[0079] Figure 12 SEM images and digital photographs of zinc surfaces after different acid treatments in Examples 2 and 3 are shown, where (a, e) H2SO4; (b, f) HOTF; (c, g) BA; (d, h) HNO3. (ad) represents acid etching, and (eh) represents GSR treatment. It can be seen that even using the same acid solutions, samples etched with aqueous solutions of sulfuric acid, benzenesulfonic acid, and trifluoromethanesulfonic acid exhibit uneven corrosion pits, while samples treated with nitric acid solution form a thick layer of needle-like zinc hydroxynitrate crystals. In contrast, the corresponding GSR treatment effectively regulates the uniformity of the interfacial reaction between the acid and zinc. The SEM images clearly show that the GSR-treated samples exhibit a smooth surface. This helps reduce the "needle-tip effect" in zinc and inhibit dendrite growth.

[0080] Figure 13 The long-cycle stability test results of the zinc foil assembled into symmetric cells show that all GSR-treated zinc exhibit significantly longer cycle lives in symmetric cells than the samples treated with corresponding acid aqueous solutions. Specifically, sulfuric acid GSR-treated zinc can cycle stably for 881 hours, while the sulfuric acid aqueous solution-etched sample fails after 383 hours. Trifluoromethanesulfonic acid GSR-treated samples can cycle stably for 3471 hours, while the corresponding aqueous solution-etched samples only cycle for 1460 hours. Benzenesulfonic acid GSR-treated samples can cycle stably for 2794 hours, while its aqueous solution-etched samples fail after only 846 hours. Benzenesulfonic acid GSR-treated samples can cycle stably for 2691 hours, while its aqueous solution-treated samples fail after only 736 hours. These results strongly demonstrate that the GSR method is a simple and versatile strategy that can effectively enhance the stability of zinc electrodes and is easily scalable.

[0081] Example 3

[0082] This example is used to investigate the effect of different polyvinyl alcohol (PVA) concentrations on the zinc foil treatment effect. Specifically:

[0083] The difference from Example 1 is that the concentration of the PVA aqueous solution in step 2) was adjusted to 0% PVA, 15% PVA and 20% PVA, while the remaining steps were the same as in Example 1, to obtain zinc foils treated with different PVA concentrations in this comparative example.

[0084] Figure 14 The images show the morphology of the zinc foil surface and cross-section after 9 hours of treatment. (a, d) show the surface and cross-section of the zinc foil after 0% PVA treatment; (b, e) show the surface and cross-section of the zinc foil after 15% PVA treatment; and (c, f) show the surface and cross-section of the zinc foil after 20% PVA treatment. It can be seen that after 9 hours of treatment with 0% PVA (i.e., aqueous solution), a dense and compacted crystallization formed on the zinc surface. With increasing PVA content, the crystallinity of zinc phosphate on the zinc surface gradually decreased, and the thickness of the crystalline layer gradually decreased. This indicates that the gel can control the reaction rate between phosphoric acid and zinc and refine the particles. At a PVA content of 20%, the surface coating became loose and porous, which may be due to the excessive PVA significantly reducing the conductivity of the phosphoric acid component during the treatment process. Considering the influence of PVA content on morphology, as well as the operability and gel flowability of the preparation process, we selected 15% PVA as the optimal content.

[0085] Example 4

[0086] This embodiment is used to investigate the effects of the concentration of different slow-release phosphoric acid components and the treatment time on the zinc foil treatment effect. Specifically:

[0087] The difference from Example 1 is that the phosphoric acid concentration in the gel solution in step 1) was adjusted to 0.1M and 1M, respectively;

[0088] In step 3), the coated zinc foil was left to stand at room temperature for 1, 4, and 8 hours, respectively. The remaining steps were performed in accordance with Example 1, resulting in zinc foils with different acid concentrations and treatment times in this comparative example.

[0089] Figure 15 The surface morphology of zinc after treatment with different phosphoric acid concentrations and times is shown. (ac) represents treatment with 0.1M phosphoric acid for 1, 4, and 8 hours, respectively; (df) represents treatment with 1M phosphoric acid for 1, 4, and 8 hours, respectively. The results show that within 4 hours, both phosphoric acid concentrations can form particulate zinc phosphate products on the zinc surface. Regardless of the phosphoric acid concentration, the distribution of particulate zinc phosphate is relatively uniform, demonstrating the feasibility of the gel-release strategy.

[0090] Although zinc phosphate was evenly distributed after treatment with 0.1M phosphoric acid for 1 hour and 4 hours, it failed to completely cover the zinc surface and thus could not form an effective protective coating. In contrast, the samples treated with 15% PVA and 1M phosphoric acid for 1 hour and 4 hours formed a uniformly covered surface coating.

[0091] In summary, this invention provides a method for in-situ construction of a zinc anode interface protective layer based on gel-release technology. By controlling the reaction rate and reaction uniformity of the slow-release components and zinc when forming the interface layer through the gel network, this invention offers significant advantages over existing methods such as polishing or acid washing, which can only temporarily remove the passivation layer and form a new passivation layer during battery cycling.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for constructing a zinc negative electrode interface protection layer in situ based on gel-based sustained release technology, characterized by: include, The hydrogel polymer is dissolved in deionized water, heated and stirred until the hydrogel polymer is completely dissolved, cooled to room temperature, and then a slow-release component is added and stirred until homogeneous to obtain a gel solution. The slow-release component is an acid or a substance that can form a zinc-like protective layer through a chemical conversion reaction. The gel solution is uniformly coated on a clean zinc foil surface, ensuring complete and uniform gel coverage. The coated zinc foil is then allowed to stand at room temperature to allow the slow-release components to react slowly with the zinc substrate, forming a uniform pre-treated coating on the zinc substrate. Scrape off any excess gel on the pre-treated coating that is not in contact with the zinc substrate, rinse with deionized water to remove any remaining gel, and finally rinse the zinc foil with anhydrous ethanol. Allow it to air dry at room temperature to obtain the zinc foil that forms the interface protective layer.

2. The method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology as described in claim 1, characterized in that: The hydrogel polymer includes one of polyvinyl alcohol, alginate, chitosan, gelatin, and polyethylene glycol.

3. The method for constructing a protective layer for zinc negative electrode interface in situ based on gel-based sustained release technology according to claim 1, characterized in that: The heating and stirring temperature is 60~95℃, and the time is 2~4h.

4. The method for in-situ construction of zinc negative electrode interface protection layer based on gel-based sustained release technology according to claim 1, characterized in that: The mass concentration of the hydrogel polymer in the gel solution is 5-20%.

5. The method for in-situ construction of zinc negative electrode interface protection layer based on gel-based sustained release technology according to claim 1, characterized in that: The acid includes one of phosphoric acid, hydrochloric acid, boric acid, formic acid, acetic acid, citric acid, and tartaric acid.

6. The method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology as described in claim 1, characterized in that: The substances that can form a zinc-like protective layer through chemical conversion reactions include one of chromates, fluorides, and phosphates.

7. The method for in-situ construction of zinc negative electrode interface protection layer based on gel-based sustained release technology according to claim 4, characterized in that: The concentration of acid in the gel solution is 0.1~3M.

8. The method for in-situ construction of a zinc anode interface protective layer based on gel sustained-release technology as described in claim 1, characterized in that: The thickness of the gel coating on the zinc foil surface is 0.1~1cm.

9. The method for in-situ construction of zinc negative electrode interface protection layer based on gel-based sustained release technology according to claim 1, characterized in that: The settling time is 1 to 4 hours.

10. The application of the zinc foil obtained by the method according to any one of claims 1 to 9 as a zinc negative electrode in the preparation of zinc batteries.

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