Zinc negative electrode containing protective film and preparation method and application thereof

Abstract

The application discloses a zinc negative electrode containing a protective film and a preparation method and application thereof. The thickness of the protective film is 0.1-10 microns; the protective film is obtained by cross-linking of polyphenol and polyamine. Residual ortho-hydroxyl groups in the molecular structure of the polyphenol after oxidation can act on various substrate surfaces to generate strong non-covalent forces including electrostatic force, hydrogen bond, pi-pi force and hydrophobic interaction force, so that the coating has good adhesion. Cross-linking of the polyphenol and the polyamine not only has high adhesion and integrity, but also can form a thin film with good adhesion to the substrate through strong covalent interaction between the polyphenol and the polyamine, namely Michael addition and Schiff base reaction. The cross-linking structure of the polyphenol-polyamine not only enhances the mechanical properties of the thin film, but also introduces rich functional groups such as hydroxyl, amine and carboxyl groups for further optimization and regulation of the deposition behavior of zinc.

Description

Technical Field

[0001] This application relates to a zinc anode containing a protective film, its preparation method, and its application, belonging to the field of electrochemical materials. Background Technology

[0002] With the increasing demand for energy and the depletion of traditional fossil fuels, along with the resulting environmental pollution, clean and renewable energy sources (such as solar, wind, and tidal power) have greatly inspired researchers. Therefore, advanced energy storage systems are being used to address issues related to safe and sustainable energy storage. Among these, lithium-ion batteries dominate the application of rechargeable batteries and have achieved great success over the past 30 years. However, growing concerns exist regarding the challenges faced by lithium-ion batteries, such as limited lithium reserves, high cost, the flammability and explosiveness of the electrolyte, and environmental problems, necessitating the search for alternatives. Highly safe and eco-friendly aqueous zinc-ion batteries can effectively overcome these challenges, and zinc metal reserves are abundant, cost is low, and theoretical capacity is high (820 mAh g / g). -1 With its low redox potential (-0.76V relative to the standard hydrogen electrode), it represents one of the most promising energy storage systems and is expected to become a replacement for lithium-ion batteries.

[0003] The zinc anode interface is unstable and leads to several problems, such as hydrogen evolution reaction, corrosion, and byproduct formation, resulting in low coulombic efficiency and poor cycle stability. Furthermore, Zn... 2+ Uneven deposition of zinc ions during stripping / electroplating leads to the formation of zinc dendrites, which further degrades zinc utilization. To address this issue, researchers have developed various strategies to stabilize zinc anodes, such as electrolyte engineering, anode structure engineering, and surface coatings. Artificially constructing a protective layer at the anode interface is an effective and simple strategy for achieving high-performance and long-cycle zinc-ion batteries.

[0004] Patent CN114792775A discloses a polymer-coated modified zinc anode and its preparation, which involves spin-coating a copolymer of polyvinylidene fluoride containing zinc salt or lithium salt onto a zinc surface. However, this method is limited to laboratory preparation. Considering that current zinc anode protection strategies suffer from one or more drawbacks, such as high cost, complex methods, insignificant performance improvement, and inability to achieve large-scale preparation, it is necessary to develop new anode protection strategies to address these issues. Summary of the Invention

[0005] To overcome the shortcomings of existing anode protection methods, this invention provides a method for preparing a polyphenol-polyamine crosslinked zinc anode film. This method crosslinks a series of low-cost, environmentally friendly polyphenol materials with polyamine materials rich in functional groups to prepare an artificial protective layer to stabilize the zinc anode. This method is simple to prepare and can be scaled up for production. It provides a universal and effective method to improve problems such as dendrite growth, corrosion and side reactions.

[0006] According to one aspect of this application, a zinc negative electrode containing a protective film is provided, the thickness of said protective film being 0.1 to 10 μm;

[0007] The protective film is obtained by crosslinking polyphenols and polyamines.

[0008] The polyphenols are selected from at least one of dopamine, catechol, pyrogallol, tannic acid, tea polyphenols, gallic acid, and caffeic acid;

[0009] The polyamine is selected from at least one of polyethyleneimine, chitosan, diethylenetriamine, triethylenetetramine, triethylamine, m-phenylenediamine, and p-phenylenediamine.

[0010] According to another aspect of this application, a method for preparing the above-mentioned zinc anode containing a protective film is provided, comprising the following steps:

[0011] The zinc anode was sequentially immersed in an aqueous solution containing polyphenols and an aqueous solution containing polyamines, and then dried to obtain the zinc anode containing a protective film.

[0012] In the aqueous solution containing polyphenols, the concentration of polyphenols is 0.01 to 1 mol / L.

[0013] In the aqueous solution containing polyamine, the concentration of polyphenol is 0.5–2 wt%.

[0014] The immersion time is 1 to 120 minutes.

[0015] The drying temperature is 40℃~80℃;

[0016] The drying time is 4 hours to 12 hours.

[0017] Specifically, it is carried out in room temperature air.

[0018] (1) Hydrophilic treatment of zinc foil: After ultrasonic cleaning with ethanol, the zinc foil cut into 10×10cm is immersed in HCl solution for a certain period of time to etch the surface. Then the zinc foil is taken out, cleaned with ethanol and dried.

[0019] The zinc foil has a thickness of 20–500 μm, preferably 20–100 μm;

[0020] The zinc foil can be treated with 0.1 mol / L HCl for 10 min, 1 mol / L HCl for 5 min, 3 mol / L HCl for 30 s, and 5 mol / L HCl for 10 s. Preferably, it is treated with 1 mol / L HCl for 5 min.

[0021] (2) First, soak the zinc foil in a polyphenol solution for 5 minutes, then remove most of the excess solution on the surface, dry it briefly, then soak the zinc foil in a polyamine solution for 5 minutes to remove most of the excess solution on the surface, and put it in an oven at 60°C for 10 hours.

[0022] According to another aspect of this application, an aqueous zinc-ion battery is provided, comprising the zinc negative electrode containing a protective film as described above.

[0023] The beneficial effects that this application can produce include:

[0024] (1) The residual ortho-hydroxy groups in the molecular structure of polyphenols after oxidation will act on various substrate surfaces, generating strong non-covalent forces, including electrostatic forces, hydrogen bonds, π-π forces, and hydrophobic interactions, which gives the coating good adhesion. Using polyphenols and polyamines for crosslinking not only has high adhesion and integrity, but also forms a thin film with good adhesion to the substrate through strong covalent interactions between polyphenols and polyamines, namely Michael addition and Schiff base reaction.

[0025] (2) The cross-linked structure of polyphenol-polyamine not only enhances the mechanical properties of the film, but also introduces a wealth of functional groups such as hydroxyl, amine, and carboxyl groups to further optimize and regulate the deposition behavior of zinc.

[0026] (3) The invention method is simple. Functional molecules are cross-linked through covalent or non-covalent interactions. No multiple steps are required. The one-step preparation method is simple and easy to carry out, and it is convenient to expand production. Attached Figure Description

[0027] Figure 1 This is a SEM image of the zinc anode of Comparative Example 1 of the present invention, with a scale of 1 μm.

[0028] Figure 2 This is a SEM image of the zinc anode of the catechol-polyethyleneimine crosslinked membrane in Example 1 of the present invention, with a scale of 1 μm.

[0029] Figure 3 The zinc anode symmetric cells prepared for Example 1 and Comparative Example 1 of this invention were tested at 0.5 mA / cm². -2 Current density, 1mAh cm -2 Comparison of cycling performance under different areal capacities.

[0030] Figure 4The zinc anode symmetric cells prepared for Example 2 and Comparative Example 1 of this invention were tested at 0.5 mA / cm². -2 Current density, 1mAh cm -2 Comparison of cycling performance under different areal capacities. Detailed Implementation

[0031] The present invention will be described in detail below with reference to examples, but this application is not limited to the following embodiments.

[0032] Comparative Example 1

[0033] Cut 100μm zinc foil into 10×10cm pieces, treat with 1mol / L HCl for 5min, then remove the zinc foil, clean the surface with ethanol and dry it.

[0034] Figure 1 This is a SEM image of the zinc anode of Comparative Example 1 of the present invention, with a scale of 1 μm.

[0035] Example 1

[0036] (1) Cut 100μm zinc foil into 10×10cm pieces, treat with 1mol / L HCl for 5min, then take out the zinc foil, clean the surface with ethanol and dry it.

[0037] (2) Prepare a fresh 0.05 mol / L catechol aqueous solution and a fresh 1.5 wt.% polyethyleneimine aqueous solution. Dissolve the two solutions by sonication for 10 min.

[0038] (3) Place the hydrophilic zinc foil into a freshly prepared catechol aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it at 60°C. Then place the zinc foil into a freshly prepared polyethyleneimine aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it.

[0039] Figure 2 This is a SEM image of the zinc anode of the catechol-polyethyleneimine crosslinked membrane in Example 1 of the present invention, with a scale of 1 μm.

[0040] Example 2

[0041] (1) Cut 100μm zinc foil into a certain size, treat it with 1mol / L HCl for 5min, then take out the zinc foil, clean the surface with ethanol and dry it.

[0042] (2) Prepare a fresh 0.05 mol / L catechol aqueous solution and a 1.5 wt.% chitosan aqueous solution. Dissolve the two solutions by sonication for 10 min.

[0043] (3) Place the hydrophilic zinc foil into a freshly prepared catechol aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it at 60°C. Then place the zinc foil into a freshly prepared chitosan aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it.

[0044] Example 3

[0045] (1) Cut 100μm zinc foil into a certain size, treat it with 0.1mol / L HCl for 10min, then take out the zinc foil, clean the surface with ethanol and dry it at 60℃ for 1h.

[0046] (2) Prepare a fresh 0.1 mol / L tannic acid aqueous solution and a 1 wt% polyethyleneimine aqueous solution. Dissolve the two solutions by sonication for 10 min.

[0047] (3) Place the hydrophilic zinc foil into a freshly prepared tannic acid aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it at 60°C. Then place the zinc foil into a freshly prepared polyethyleneimine aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it.

[0048] Example 4

[0049] (1) Cut 100μm zinc foil into a certain size, treat with 10mol / L HCl for 10s, then remove the zinc foil and rinse with ethanol.

[0050] Dry the surface after cleaning.

[0051] (2) Prepare a fresh 0.1 mol / L moscalamic acid aqueous solution and a 1 wt.% polyethyleneimine aqueous solution. Dissolve the two solutions by sonication for 10 min.

[0052] (3) Place the hydrophilic zinc foil into a freshly prepared moscari acid aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution on the surface, and dry it at 60°C. Then place the zinc foil into a freshly prepared polyethyleneimine aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution on the surface, and dry it.

[0053] Example 5

[0054] (1) Cut 100μm zinc foil into a certain size, treat it with 1mol / L HCl for 5min, then take out the zinc foil, clean the surface with ethanol and dry it at 60℃ for 1h.

[0055] (2) Prepare a fresh 0.01 mol / L dopamine aqueous solution and a 1 wt% polyethyleneimine aqueous solution. Dissolve the two solutions by sonication for 10 min.

[0056] (3) Place the hydrophilic zinc foil into a freshly prepared dopamine aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it at 60°C. Then place the zinc foil into a freshly prepared polyethyleneimine aqueous solution, let it stand at room temperature for 5 minutes, then remove the zinc foil, remove the excess solution from the surface, and dry it.

[0057] Example 6

[0058] (1) The zinc negative electrodes prepared in Examples 1-5 and Comparative Example 1 were cut into 15 mm diameter plates and assembled into symmetrical cells. The positive and negative electrodes were untreated zinc and zinc plates with polyphenol-polyamine protective films, the separator was glass fiber, and the electrolyte was 2 mol / L Zn(CH3SO3)2. The zinc negative electrode was placed in the positive electrode shell, and then the positive electrode plate and the separator were added in sequence. The electrolyte was added dropwise until the separator was completely wetted. Then the negative electrode plate, stainless steel gasket, spring sheet and negative electrode shell were added in sequence. Then the cells were placed in a static pressure press for static pressure sealing. The resulting aqueous zinc-ion symmetrical cell was prepared.

[0059] (2) Symmetrical battery performance test: The assembled symmetrical battery was clamped in the battery channel of the Xinwei testing system and tested at 0.5 mA / cm. -2 Current density, 1mAh cm -2 Constant current charge-discharge test was performed on the surface capacity.

[0060] Figure 3 The zinc anode symmetric cells prepared for Example 1 and Comparative Example 1 of this invention were tested at 0.5 mA / cm². -2 Current density, 1mAh cm -2 Comparison of cycling performance under different areal capacities.

[0061] Figure 4 The zinc anode symmetric cells prepared for Example 2 and Comparative Example 1 of this invention were tested at 0.5 mA / cm². -2 Current density, 1mAh cm -2 Comparison of cycling performance under different areal capacities.

[0062] As shown in the figure, the catechol and polyethyleneimine cross-linked film zinc anode has better cycle life and cycle stability compared to the bare zinc anode.

[0063] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A zinc negative electrode containing a protective film, characterized in that, The thickness of the protective film is 0.1~10μm; The protective film is formed by a cross-linking reaction of polyphenols and polyamines. The polyphenols mentioned therein are selected from at least one of dopamine, catechol, pyrogallol, tannic acid, tea polyphenols, gallic acid, and caffeic acid; The polyamine is selected from at least one of polyethyleneimine, chitosan, diethylenetriamine, triethylenetetramine, triethylamine, m-phenylenediamine, and p-phenylenediamine; The protective film is formed by sequentially immersing the zinc negative electrode in an aqueous solution containing polyphenols and an aqueous solution containing polyamines, followed by a drying step to form a cross-linked structure.

2. The zinc negative electrode containing a protective film according to claim 1, characterized in that, In the aqueous solution containing polyphenols, the concentration of polyphenols is 0.01~1 mol / L.

3. A zinc negative electrode containing a protective film according to claim 1, characterized in that, In the aqueous solution containing polyamine, the concentration of polyphenol is 0.5~2wt%.

4. A zinc negative electrode containing a protective film according to claim 1, characterized in that, The immersion time is 1 to 120 minutes.

5. A zinc negative electrode containing a protective film according to claim 1, characterized in that, The drying temperature is 40℃~80℃; The drying time is 4h to 12h.

6. An aqueous zinc-ion battery, characterized in that, Includes the zinc negative electrode containing a protective film as described in claim 1.

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