Zinc pole piece coated with sulfonyl COF membrane, preparation method of zinc pole piece and aqueous zinc battery

Abstract

The invention relates to the technical field of battery electrodes, in particular to a zinc pole piece coated with a sulfonic COF membrane, a preparation method of the zinc pole piece and an aqueous zinc battery, and the preparation method comprises the following steps: dissolving 2, 4, 6-triformyl phloroglucinol and p-phenylenediamine-2, 5-disulfonic acid in an organic solvent to obtain a mixed solution; and putting the zinc foil into the mixed solution, carrying out sealed standing at normal temperature, taking out the zinc foil coated with the sulfonic group COF film, and washing and drying the zinc foil to obtain the zinc pole piece coated with the sulfonic group COF film. The prepared zinc pole piece coated with the sulfonic COF film has good corrosion resistance and dendritic crystal inhibition capacity, and when the zinc pole piece is used as a negative electrode of a water-based zinc battery, the cycle performance of the water-based zinc battery can be improved, and the cycle life of the water-based zinc battery can be prolonged; the problems that a zinc negative electrode of an existing water-based zinc battery is prone to generating dendritic crystal and corrosion passivation side reactions in the battery circulation process, so that the use performance of the water-based zinc battery is reduced, and the service life is greatly shortened are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrodes, and in particular to a zinc electrode coated with a sulfonic acid group COF film, a preparation method thereof, and an aqueous zinc battery. Background Art

[0002] Zinc (Zn) has a low redox potential, with a standard hydrogen electrode potential of -0.76V, and is highly stable in aqueous solution. Aqueous zinc battery systems often use zinc as the negative electrode and rely on zinc ions (Zn) in the electrolyte (the electrolyte is water or an aqueous solution). 2+ ) Migrate between the positive and negative electrodes to achieve charging and discharging. There are no toxic substances in the aqueous zinc battery system, which makes the aqueous zinc battery relatively safe and is an important research direction for sustainable chemical energy storage system technology.

[0003] However, the zinc negative electrode of the current aqueous zinc battery is prone to problems such as dendrites, corrosion and passivation side reactions during the battery cycle, which leads to a decline in the performance of the aqueous zinc battery and a significant reduction in its service life. Summary of the Invention

[0004] In response to the problems raised in the background technology, the first purpose of the present invention is to propose a method for preparing a zinc electrode coated with a sulfonic acid COF film. The prepared zinc electrode coated with a sulfonic acid COF film has good corrosion resistance and dendrite inhibition ability. When used as the negative electrode of an aqueous zinc battery, it can improve the cycle performance of the aqueous zinc battery and extend the cycle life, and solve the problem that the zinc negative electrode of the existing aqueous zinc battery is prone to dendrites and corrosion passivation side reactions during the battery cycle, resulting in a decrease in the performance of the aqueous zinc battery and a significant reduction in its service life.

[0005] The second object of the present invention is to propose a zinc electrode sheet coated with a sulfonic acid COF membrane, which is prepared by any of the above-mentioned methods for preparing a zinc electrode sheet coated with a sulfonic acid COF membrane. It has good corrosion resistance and dendrite inhibition capabilities. When used as a negative electrode of an aqueous zinc battery, it can improve the cycle performance of the aqueous zinc battery and extend the cycle life, and solve the problem that the zinc negative electrode of the existing aqueous zinc battery is prone to dendrites and corrosion passivation side reactions during the battery cycle, resulting in a decrease in the performance of the aqueous zinc battery and a significant reduction in its service life.

[0006] The third object of the present invention is to provide an aqueous zinc ion battery, comprising any one of the above-mentioned zinc electrodes coated with a sulfonic acid COF film, which has high cycle performance and long cycle life, and solves the problem that the zinc negative electrode of the existing aqueous zinc battery is prone to produce dendrites and corrosion passivation side reactions during the battery cycle, resulting in a decrease in the performance of the aqueous zinc battery and a significant reduction in its service life.

[0007] To achieve the above-mentioned purpose, the present invention proposes a method for preparing a zinc electrode coated with a sulfonic acid COF film, comprising the following steps: step S1, dissolving 2,4,6-triformylphloroglucinol and p-phenylenediamine-2,5-disulfonic acid in an organic solvent to obtain a mixed solution; step S2, placing a zinc foil in the mixed solution, sealing and standing it at room temperature so that the surface of the zinc foil is coated with the sulfonic acid COF film; step S3, taking out the zinc foil coated with the sulfonic acid COF film, rinsing and drying it to obtain a zinc electrode coated with the sulfonic acid COF film.

[0008] Optionally, the mass ratio of the added amounts of the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid is 1:2~3.8; and the organic solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

[0009] Optionally, the following steps are further included between step S1 and step S2: S11, performing ultrasonic treatment on the mixed solution.

[0010] Optionally, in step S2, the zinc foil needs to be polished before being placed in the mixed solution, and the polished zinc foil is rinsed with anhydrous ethanol and deionized water and then placed in an acetone solution for standby use.

[0011] Optionally, in step S2, the sealed and standing period at room temperature is 1 to 5 days.

[0012] Optionally, in step S3, the zinc foil coated with the sulfonic acid COF film is rinsed with anhydrous ethanol and deionized water in sequence and then dried. The drying temperature is 65° C. to 80° C., and the drying time is 1 hour to 2 hours.

[0013] The present invention also provides a zinc electrode coated with a sulfonic acid COF film, which is prepared by any of the above-mentioned methods for preparing a zinc electrode coated with a sulfonic acid COF film.

[0014] The present invention also provides an aqueous zinc battery, comprising a zinc electrode coated with a sulfonic acid COF membrane as described in any one of the above items, wherein the negative electrode of the aqueous zinc battery is the zinc electrode coated with the sulfonic acid COF membrane.

[0015] Optionally, the positive electrode of the aqueous zinc battery is one of a manganese dioxide electrode, a copper electrode, a stainless steel electrode or another zinc electrode coated with a sulfonic acid COF film.

[0016] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: 1. In the preparation method of the zinc electrode coated with a sulfonic acid COF film of the present invention, the hydroxyl group in 2,4,6-triformylphloroglucinol and the amino group in p-phenylenediamine-2,5-disulfonic acid spontaneously undergo dehydration condensation to form a chemical bond, so that the outer surface of the zinc foil is covered with a sulfonic acid COF film having an ordered pore structure. When the prepared zinc electrode coated with the sulfonic acid COF film is used as the negative electrode of aqueous zinc ions, the pore structure on the surface of the sulfonic acid COF film increases the specific surface area of the negative electrode interface. At the same time, the nitrogen, oxygen and other elements contained in the sulfonic acid COF film are conducive to the formation of hydrogen bonds, thereby increasing the affinity of the negative electrode interface to the electrolyte (zinc sulfate electrolyte) and improving the wettability of the negative electrode surface. The good interface wettability can enable zinc ions to be transported faster during the charge and discharge process of the aqueous zinc battery, which helps to improve the charge and discharge efficiency and battery capacity retention rate of the aqueous zinc battery, extend the cycle life of the aqueous zinc battery, and improve the cycle stability.

[0017] 2. When the zinc electrode coated with sulfonic acid COF membrane is used as the negative electrode of aqueous zinc ions, the pore structure of the sulfonic acid COF membrane can inhibit the diffusion of water molecules to the negative electrode interface and exclude sulfate ions and other anions from the pore structure, which can reduce the contact between water molecules and the negative electrode surface, thereby inhibiting hydrogen evolution and oxygen absorption corrosion reactions; in addition, the sulfonic acid sites attached to the inside of the pore structure are zinc-philic sites (sulfonic acid groups can interact strongly with zinc ions, reduce the coordinated water of zinc ions, and accelerate the transmission of zinc ions in the pore structure to the negative electrode surface). The pore structure and the sulfonic acid group sites can guide the uniform and rapid deposition of zinc ions on the surface of the negative electrode, achieving a dense and flat deposited zinc on the negative electrode surface. This allows the zinc ions present in the form of hydrated ions in the zinc sulfate electrolyte to be desolvated and rapidly transported, helping to inhibit dendrite growth, reduce corrosion and passivation byproducts, and ensure that the prepared zinc electrode sheet coated with the sulfonic acid group COF film has good corrosion resistance and dendrite inhibition capabilities, helping to improve the cycle performance and extend the cycle life of aqueous zinc batteries. This can solve the problems of the zinc negative electrode of existing aqueous zinc ion batteries that are prone to dendrites, corrosion and passivation side reactions during battery cycling, resulting in reduced battery performance and short service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The reaction formula of 2,4,6-triformylphloroglucinol and p-phenylenediamine-2,5-disulfonic acid in the preparation method of the zinc electrode coated with the sulfonic acid COF film according to one embodiment of the present invention is as follows; Figure 2 Schematic diagram of a method for preparing a zinc electrode coated with a sulfonic acid COF film according to an embodiment of the present invention, wherein Figure 2 (a) is a schematic diagram of zinc foil in a method for preparing a zinc electrode coated with a sulfonic acid COF film according to an embodiment of the present invention. Figure 2 (b) is a schematic diagram of placing zinc foil into a mixed solution in a method for preparing a zinc electrode coated with a sulfonic acid COF film according to an embodiment of the present invention; Figure 2 (c) is a schematic diagram of a zinc electrode coated with a sulfonic acid COF film according to an embodiment of the present invention (after being sealed and left to stand for 3 days at room temperature); Figure 3 This is a schematic diagram of the process of gradually covering the sulfonic acid group COF film on the zinc foil in the method for preparing the zinc electrode coated with the sulfonic acid group COF film according to one embodiment of the present invention; Figure 4 This is a diagram illustrating the mechanism of using a zinc electrode coated with a sulfonic acid COF film as a negative electrode for an aqueous zinc battery according to an embodiment of the present invention; Figure 5 The results of the interface wettability test of the comparative example and the embodiment are shown in FIG. Figure 5 (a) is a graph showing the interface wettability test results of the commercial zinc electrode (Bare Zn) of Comparative Example 1 of the present invention. Figure 5 (b) is a graph showing the interface wettability test results of the zinc electrode A (COF-Zn) coated with a sulfonic acid COF film according to Example 1 of the present invention; Figure 6 The SEM (scanning electron microscope) microscopic morphology images of the comparative example and the embodiment before and after immersion are shown in FIG. Figure 6 (a) is a SEM (scanning electron microscope) microscopic image of the commercial zinc electrode (Bare Zn) of Comparative Example 1 of the present invention before immersion. Figure 6 (b) is a SEM microscopic image of the commercial zinc electrode (Bare Zn) after immersion in Comparative Example 1 of the present invention. Figure 6 (c) is a SEM microscopic image of the zinc electrode A (COF-Zn) coated with a sulfonic acid COF film according to Example 1 of the present invention after immersion; Figure 7 Surface XRD (X-ray diffraction) component scanning results of the zinc electrode A (COF-Zn) coated with a sulfonic acid COF film according to Example 1 of the present invention and the commercial zinc electrode (Bare Zn) according to Comparative Example 1 after immersion for 7 days; Figure 8 Graphs showing the coulombic efficiency curves of aqueous zinc battery C of Example 3 of the present invention and aqueous zinc battery F of Comparative Example 3; Figure 9 Graphs showing cyclic polarization voltage curves of aqueous zinc battery B of Example 2 of the present invention and aqueous zinc battery E of Comparative Example 2; Figure 10 Specific capacity / coulombic efficiency cycle curve results of aqueous zinc battery A of Example 1 of the present invention and aqueous zinc battery D of Comparative Example 1; Figure 11The thickness measurement results of aqueous zinc batteries before and after cycling in comparative examples and embodiments are shown in FIG. Figure 11 (a) is a graph showing the thickness measurement results of aqueous zinc battery B before cycling in Example 2 of the present invention. Figure 11 (b) is a graph showing the thickness measurement results of the aqueous zinc battery of Comparative Example 2 of the present invention after E cycles. Figure 11 (c) is a graph showing the thickness measurement results of aqueous zinc battery B after cycling according to Example 2 of the present invention; Figure 12 This is a schematic diagram of the partial structure of the sulfonic acid COF film in the zinc electrode coated with the sulfonic acid COF film according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention provides a method for preparing a zinc electrode coated with a sulfonic acid COF film, comprising the following steps: Step S1, dissolving 2,4,6-triformylphloroglucinol and p-phenylenediamine-2,5-disulfonic acid in an organic solvent to obtain a mixed solution; Step S2, placing a zinc foil in the mixed solution, and allowing the mixture to stand in a sealed container at room temperature, so that the surface of the zinc foil is covered with a sulfonic acid COF film; Step S3: taking out the zinc foil coated with the sulfonic acid COF film, rinsing and drying it to obtain a zinc electrode coated with the sulfonic acid COF film.

[0020] The preparation method of the zinc electrode coated with sulfonic acid COF film of the present invention uses the 2,4,6-triformyl phloroglucinol and the p-phenylenediamine-2,5-disulfonic acid as precursors. At room temperature and in a closed environment, the hydroxyl group in the 2,4,6-triformyl phloroglucinol and the amino group in the p-phenylenediamine-2,5-disulfonic acid spontaneously undergo dehydration condensation to form a chemical bond (see the chemical reaction formula for details). Figure 1 , Figure 1 (where n refers to the number of moles) to form a sulfonic acid COF film on the outer surface of the zinc foil (COF film refers to a covalent organic framework, which is a crystalline porous material formed by organic monomers connected by covalent bonds. The sulfonic acid COF film refers to a membrane structure in which sulfonic acid groups are embedded in the skeleton of the covalent organic framework); please refer to Figure 2 and Figure 3 As the reaction proceeds, the mixed solution gradually changes from yellow to dark brown, indicating that the degree of polymerization of the reaction gradually deepens, and the outer surface of the zinc foil placed in the mixed solution is gradually covered by the yellow sulfonic acid COF film formed by polycondensation.

[0021] It should be noted that the prepared zinc electrode coated with the sulfonic acid COF membrane can be used in aqueous zinc batteries; wherein, the negative electrode of the aqueous zinc battery can be the zinc electrode coated with the sulfonic acid COF membrane, and the positive electrode of the aqueous zinc battery can also be the zinc electrode coated with the sulfonic acid COF membrane.

[0022] More specifically, the aqueous zinc battery realizes charge and discharge by the migration of zinc ions in the electrolyte between the positive electrode and the negative electrode. The electrolyte is a zinc sulfate electrolyte. Since most zinc ions exist in the form of hydrated ions in the zinc sulfate electrolyte, during the charge and discharge process of the aqueous zinc battery, the zinc ions in the form of hydrated ions need to be separated from the solvent molecules (such as water molecules) and converted into bare zinc ions (Zn 2+ ) before it can be deposited on the electrodes of the aqueous zinc battery. Figure 4 and Figure 12 In the preparation method of the zinc electrode coated with the sulfonic acid COF film of the present invention, the hydroxyl group in the 2,4,6-triformyl phloroglucinol and the amino group in the p-phenylenediamine-2,5-disulfonic acid will spontaneously undergo dehydration condensation to form a chemical bond, so that the outer surface of the zinc foil is covered with a sulfonic acid COF film with an ordered pore structure (wherein, Figure 12 (Figure 3 is a schematic diagram showing a pore structure of the sulfonic acid COF membrane). When the zinc electrode coated with the sulfonic acid COF membrane is prepared and used as the negative electrode for the aqueous zinc ion, the pore structure allows a single zinc ion to pass through, which has a positive effect on the desolvation and transport of hydrated zinc ions. In addition, the pore structure on the surface of the sulfonic acid COF membrane increases the specific surface area of the negative electrode interface. At the same time, the nitrogen, oxygen and other elements contained in the sulfonic acid COF membrane are conducive to the formation of hydrogen bonds, thereby increasing the affinity of the negative electrode interface for the electrolyte (zinc sulfate electrolyte) and improving the wettability of the negative electrode surface. Good interfacial wettability can facilitate faster transmission of zinc ions during the charge and discharge process of the aqueous zinc battery, helping to improve the charge and discharge efficiency and battery capacity retention of the aqueous zinc battery, extend the cycle life of the aqueous zinc battery, and improve cycle stability.

[0023] Please continue reading Figure 4 The pore structure can inhibit the diffusion of water molecules (H2O) to the negative electrode interface and transfer sulfate ions (SO4 2- ) is excluded from the pore structure, which can reduce the contact between water molecules and the negative electrode surface, thereby inhibiting the hydrogen evolution and oxygen absorption corrosion reactions; in addition, the sulfonic acid sites attached to the inside of the pore structure are zinc-philic sites (sulfonic acid groups (-SO3H) can react with zinc ions (Zn 2+) to produce a strong interaction, reduce the coordinated water of zinc ions, and accelerate the transmission of zinc ions in the pore structure to the surface of the negative electrode). The pore structure and the sulfonic acid site can guide the zinc ions to deposit uniformly and quickly on the surface of the negative electrode, so that the deposited zinc on the surface of the negative electrode can achieve the purpose of dense and flat quality, thereby enabling the zinc ions in the form of hydrated ions in the zinc sulfate electrolyte to achieve desolvation and rapid transmission of zinc ions, and help to inhibit dendrite growth, reduce corrosion and passivation by-products. The prepared zinc electrode coated with the sulfonic acid COF film has good corrosion resistance and dendrite inhibition ability, which helps to improve the cycle performance of the aqueous zinc battery and extend the cycle life of the aqueous zinc battery.

[0024] Please continue reading Figure 1 and Figure 4 The present invention uses the p-phenylenediamine-2,5-disulfonic acid as one of the precursors, wherein the p-phenylenediamine-2,5-disulfonic acid has two sulfonic acid groups, so that the zinc electrode of the formed sulfonic acid group-coated COF film has more sulfonic acid sites (zinc-philic sites), thereby exhibiting better zinc-philic transport ability, further realizing the desolvation and rapid transport of zinc ions, and effectively improving the cycle performance and cycle life of the aqueous zinc battery; thereby solving the problems of the zinc negative electrode of the existing aqueous zinc ion battery being prone to dendrites, corrosion and passivation side reactions during the battery cycle, resulting in reduced battery performance and short service life.

[0025] In addition, the preparation method of the zinc electrode coated with the sulfonic acid COF film described in the present invention is based on the Schiff base reaction principle, and the entire reaction process is carried out at room temperature. The prepared zinc electrode coated with the sulfonic acid COF film has the sulfonic acid COF film coated on the surface of the zinc foil being continuous and uniform in thickness, and the preparation process is simple and easy to operate.

[0026] Further, the mass ratio of the added amounts of the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid is 1:2~3.8; and the organic solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

[0027] See also Figure 1 Specifically, the molar ratio of the 2,4,6-triformylphloroglucinol to the p-phenylenediamine-2,5-disulfonic acid is 1:2~3.8.

[0028] More specifically, the amount of N,N-dimethylformamide added needs to be sufficient to completely dissolve the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid.

[0029] To further illustrate, the following steps are further included between step S1 and step S2: S11, performing ultrasonic treatment on the mixed solution.

[0030] By subjecting the mixed solution to ultrasonic treatment, the complete dissolution of the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid in the N,N-dimethylformamide (DMF) can be accelerated, and the uniformity and stability of the mixed solution can be improved, ensuring that the solutes (the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid) are evenly distributed in the solvent (the N,N-dimethylformamide), so that the sulfonic acid-based COF film formed on the outer surface of the zinc foil is coherent and has uniform thickness.

[0031] It is further explained that the duration of the ultrasonic treatment is 8 minutes to 12 minutes.

[0032] To further illustrate, in step S2, the zinc foil needs to be polished before being placed in the mixed solution. The polished zinc foil is rinsed with anhydrous ethanol and deionized water and then placed in an acetone solution for standby use.

[0033] Specifically, the zinc foil can be polished using 2000-mesh and 5000-mesh sandpapers in sequence, and the thickness of the zinc foil after polishing is 0.1 mm.

[0034] By polishing the zinc foil, defects on the surface of the zinc foil (such as microcracks, scratches, creases, etc.) can be eliminated, and the electric field uniformity of the zinc foil can be prevented from being destroyed due to the presence of the defects, thereby preventing zinc ions from preferentially depositing at the defects of the zinc foil during the charging and discharging process to form sharp zinc dendrites; in addition, by polishing the zinc foil, the zinc oxide passivation layer, surface oxide layer and oil layer that may be formed on the surface of the zinc foil can also be removed.

[0035] In addition, the polished zinc foil is rinsed with anhydrous ethanol and deionized water in sequence, and then placed in an acetone solution for standby use. This can further remove contaminants on the surface of the zinc foil and prevent the zinc foil from being contaminated again. Specifically, the polished zinc foil is rinsed with anhydrous ethanol and deionized water in sequence 2 to 3 times.

[0036] To further illustrate, in step S2, the sealed and standing period at room temperature is 1 to 5 days.

[0037] By placing the zinc foil in the mixed solution and sealing and standing it at room temperature for 1 to 5 days, the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid are fully reacted, polymerized and crystallized, so that the surface of the zinc electrode coated with the sulfonic acid COF film is formed with the sulfonic acid COF film having an ordered pore structure, and the formed sulfonic acid COF film is coherent and uniform in thickness.

[0038] To further illustrate, in step S3, the zinc foil coated with the sulfonic acid COF film is rinsed with anhydrous ethanol and deionized water in sequence and then dried. The drying temperature is 65° C. to 80° C., and the drying time is 1 hour to 2 hours.

[0039] By sequentially rinsing the zinc foil coated with the sulfonic acid COF film with anhydrous ethanol and deionized water, the organic solvent (the N,N-dimethylformamide) used in the reaction process can be removed, and the unreacted 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid monomer or other organic impurities can be removed. When the prepared zinc electrode coated with the sulfonic acid COF film is used in the aqueous zinc battery, the residue can be prevented from inducing side reactions during the cycle of the aqueous zinc battery, thereby affecting the cycle performance and cycle life of the aqueous zinc battery.

[0040] Specifically, optionally, the zinc foil coated with the sulfonic acid COF film is rinsed 2 to 3 times with anhydrous ethanol and deionized water in sequence.

[0041] The present invention also provides a zinc electrode coated with a sulfonic acid COF film, which is prepared by any of the above-mentioned methods for preparing a zinc electrode coated with a sulfonic acid COF film.

[0042] The preparation method of the zinc electrode sheet coated with the sulfonic acid COF film of the present invention is to form a chemical bond by spontaneously dehydrating and condensing the hydroxyl group in the 2,4,6-triformyl phloroglucinol and the amino group in the p-phenylenediamine-2,5-disulfonic acid to form a sulfonic acid COF film with an ordered pore structure and coating the outer surface of the zinc foil. When the zinc electrode sheet coated with the sulfonic acid COF film is used as the negative electrode of the aqueous zinc battery, the sulfonic acid COF film covering the outer surface of the zinc foil exhibits good negative electrode interface protection ability, which can improve the infiltration degree of the negative electrode surface. The pore structure can inhibit the diffusion of water molecules to the negative electrode interface and exclude sulfate ions and other anions from the pore structure, which can reduce the interaction between water molecules and the negative electrode surface. At the same time, the sulfonic acid sites attached to the inside of the pore structure are zinc-philic sites (sulfonic acid groups can strongly interact with zinc ions, reduce the coordinated water of zinc ions, and accelerate the transmission of zinc ions in the pore structure to the surface of the negative electrode). The pore structure and the sulfonic acid sites can guide the uniform and rapid deposition of zinc ions, thereby realizing the desolvation and rapid transmission of zinc ions, which helps to inhibit dendrite growth, reduce corrosion and passivation by-products. The prepared zinc electrode coated with the sulfonic acid COF film has good corrosion resistance and dendrite inhibition ability, which helps to improve the cycle performance of the aqueous zinc battery, extend the cycle life of the aqueous zinc battery, and improve the cycle stability of the aqueous zinc battery.

[0043] The present invention also proposes an aqueous zinc battery, comprising a zinc electrode sheet coated with a sulfonic acid COF membrane as described above, wherein the negative electrode of the aqueous zinc battery is the zinc electrode sheet coated with the sulfonic acid COF membrane.

[0044] To further illustrate, the positive electrode of the aqueous zinc battery is one of a manganese dioxide electrode, a copper electrode, a stainless steel electrode or another zinc electrode coated with a sulfonic acid COF film.

[0045] To be more specific, the zinc electrode coated with a sulfonic acid COF membrane described in the present invention can be applied to the aqueous zinc battery; wherein, the negative electrode of the aqueous zinc battery is the zinc electrode coated with a sulfonic acid COF membrane, and the positive electrode of the aqueous zinc battery can be one of the zinc electrode coated with a sulfonic acid COF membrane, a manganese dioxide electrode or a copper electrode.

[0046] In one embodiment, the negative electrode is the zinc electrode coated with the sulfonic acid COF membrane, the positive electrode is the zinc electrode coated with the sulfonic acid COF membrane, and the prepared aqueous zinc battery is a symmetrical battery.

[0047] In another embodiment, the negative electrode is the zinc electrode coated with the sulfonic acid COF film, the positive electrode is the manganese dioxide electrode, and the prepared aqueous zinc battery is a full battery, wherein the manganese dioxide electrode contains 80% active material, that is, the content of the manganese dioxide electrode is: manganese dioxide accounts for 80% by mass, and the total mass of fillers such as binders and conductive agents accounts for 20%.

[0048] In another embodiment, the negative electrode is the zinc electrode coated with the sulfonic acid COF film, the positive electrode is the copper electrode, and the prepared aqueous zinc battery is an asymmetric battery.

[0049] When the zinc electrode sheet coated with the sulfonic acid COF film described in the present invention is used as the negative electrode of the aqueous zinc battery, the sulfonic acid COF film covering the outer surface of the zinc electrode sheet (i.e., the zinc foil) exhibits good interface protection ability for the zinc electrode sheet, can guide the uniform and rapid deposition of zinc ions, realize the desolvation and rapid transmission of zinc ions, and at the same time help to inhibit dendrite growth, reduce corrosion and passivation by-products. The prepared zinc electrode sheet coated with the sulfonic acid COF film has good corrosion resistance and dendrite inhibition ability, thereby improving the cycle performance and cycle stability of the aqueous zinc battery and extending the cycle life of the aqueous zinc battery. It can solve the problems of the zinc negative electrode of the existing aqueous zinc ion battery being prone to dendrite generation, corrosion and passivation side reactions during the battery cycle, resulting in reduced battery performance and short service life.

[0050] Further, the aqueous zinc battery also includes a battery shell (the battery shell includes a positive electrode shell and a negative electrode shell), and the positive electrode, the negative electrode, the diaphragm, the zinc sulfate electrolyte, the gasket and the spring are arranged in the battery shell. Specifically, it should be noted that the specific structure and assembly method of the aqueous zinc battery described in the present invention are the same as those of the existing button battery or cylindrical battery, and the only difference is that the materials of the positive electrode and the negative electrode are different.

[0051] Further explanation: the model of the battery shell is a 2032 button battery shell, the diameter size of the negative electrode and the diameter size of the positive electrode are both 12 mm; the diaphragm is a glass fiber diaphragm.

[0052] To further illustrate, when assembling the aqueous zinc ion battery, the zinc electrode sheet coated with the sulfonic acid COF film needs to be punched according to the predetermined size of the positive electrode or the negative electrode. Specifically, in other embodiments, the zinc foil can also be punched according to the size of the positive electrode or the negative electrode before being polished, and then the punched zinc foil is polished, and then the polished zinc foil is placed in the mixed solution, so that the outer surface of the polished zinc foil is covered with the sulfonic acid COF film, thereby obtaining the final zinc electrode sheet coated with the sulfonic acid COF film.

[0053] To further illustrate, the size of the zinc electrode coated with the sulfonic acid COF film can also be punched according to the type or specification of the aqueous zinc battery to be prepared.

[0054] For ease of understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0055] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0056] (1) Example 1 and Comparative Example 1: (1) Example 1: ① Preparation of zinc electrode coated with sulfonic acid COF film: According to the following preparation method of zinc electrode coated with sulfonic acid COF film, zinc electrode A (COF-Zn) with sulfonic acid COF film is prepared: Step S1, dissolving 6.0 mg of 2,4,6-triformylphloroglucinol and 12.2 mg of p-phenylenediamine-2,5-disulfonic acid in 40 mL of N,N-dimethylformamide to obtain a mixed solution; Step S11, subjecting the mixed solution to ultrasonic treatment for 10 minutes; Step S2, polishing the zinc foil using 2000 mesh and 5000 mesh sandpaper in sequence, wherein the thickness of the zinc foil after polishing is 0.1 mm, and rinsing the polished zinc foil with anhydrous ethanol and deionized water twice in sequence, placing the polished and rinsed zinc foil in the mixed solution, and sealing and standing at room temperature for 3 days to coat the surface of the zinc foil with a sulfonic acid COF film; Step S3: Take out the zinc foil coated with the sulfonic acid COF film, rinse it with anhydrous ethanol and deionized water in sequence, and dry it at a drying temperature of 80° C. and a drying time of 1 hour to obtain a zinc electrode A coated with the sulfonic acid COF film.

[0057] ② The aqueous zinc battery A is prepared using the zinc electrode A coated with the sulfonic acid COF film: Assemble in a 2032-type button battery case (including a positive electrode case and a negative electrode case), with the corresponding assembly order being positive electrode case, positive electrode, separator, zinc sulfate electrolyte (the content of zinc sulfate electrolyte is 120 μL), negative electrode, gasket, spring and negative electrode case; The negative electrode is the prepared zinc electrode A coated with the sulfonic acid COF membrane, and the positive electrode is a manganese dioxide electrode (80% active material, that is, the content of the manganese dioxide electrode is: manganese dioxide accounts for 80% by mass, and the total mass of fillers such as binders and conductive agents accounts for 20%). The diameters of the positive and negative electrodes are both 12 mm, and the separator is a glass fiber separator. After assembly, an aqueous zinc battery A can be obtained (the type of aqueous zinc battery A is a functional button full battery). The assembled aqueous zinc battery A is placed on a button battery sealing machine for pressure sealing and then left to stand for 12 hours for electrochemical performance testing.

[0058] (2) Comparative Example 1: Aqueous zinc battery D was prepared using commercial zinc electrode (Bare Zn), wherein the commercial zinc electrode was a zinc foil product of Cluder, and the thickness of the zinc foil product was 0.1 mm: The difference between the aqueous zinc battery D of Comparative Example 1 and the aqueous zinc battery A of Example 1 is that the negative electrode of the aqueous zinc battery D uses a commercial zinc electrode (the outer surface of the commercial zinc electrode is not coated with a sulfonic acid COF film), and the rest of the preparation method and raw materials are the same as those of the aqueous zinc battery A of Example 1; (II) Example 2 and Comparative Example 2: (1) Example 2: ① Preparation of zinc electrode coated with sulfonic acid COF membrane: According to the following preparation method of zinc electrode coated with sulfonic acid COF membrane, zinc electrode B with sulfonic acid COF membrane is prepared: Step S1, dissolving 6.0 mg of 2,4,6-triformylphloroglucinol and 18.0 mg of p-phenylenediamine-2,5-disulfonic acid in 50 mL of N,N-dimethylformamide to obtain a mixed solution; Step S11, subjecting the mixed solution to ultrasonic treatment for 8 minutes; Step S2, polishing the zinc foil using 2000 mesh and 5000 mesh sandpaper in sequence, wherein the thickness of the zinc foil after polishing is 0.1 mm, and the polished zinc foil is rinsed three times with anhydrous ethanol and deionized water in sequence, and the polished and rinsed zinc foil is placed in the mixed solution and allowed to stand at room temperature for 5 days in a sealed manner so that the surface of the zinc foil is coated with a sulfonic acid COF film; Step S3: Take out the zinc foil coated with the sulfonic acid COF film, rinse it with anhydrous ethanol and deionized water in sequence, and dry it at a drying temperature of 80° C. and a drying time of 1 hour to obtain a zinc electrode A coated with the sulfonic acid COF film.

[0059] ② The aqueous zinc battery B is prepared by using the zinc electrode B coated with the sulfonic acid COF film: Assemble in a 2032-type button battery case (including a positive electrode case and a negative electrode case), with the corresponding assembly order being positive electrode case, positive electrode, separator, zinc sulfate electrolyte (the content of zinc sulfate electrolyte is 120 μL), negative electrode, gasket, spring and negative electrode case; The negative electrode is the prepared zinc electrode piece B coated with the sulfonic acid COF membrane, the positive electrode is another prepared zinc electrode piece B coated with the sulfonic acid COF membrane, the diameter of each positive and negative electrode is 12 mm, and the separator is a glass fiber separator. After assembly, an aqueous zinc battery B is obtained (the type of aqueous zinc battery B is a functional button-type symmetrical battery). The assembled aqueous zinc battery B is placed in a button cell sealing machine for pressure sealing and then left to stand for 12 hours for electrochemical performance testing.

[0060] (2) Comparative Example 2: Aqueous zinc battery E was prepared using the commercial zinc electrode (Bare Zn) used in Comparative Example 1: The difference between the aqueous zinc battery E of Comparative Example 2 and the aqueous zinc battery B of Example 2 is that the positive electrode of the aqueous zinc battery E uses a commercial zinc electrode (not coated with a sulfonic acid COF membrane), and the negative electrode of the aqueous zinc battery E uses another commercial zinc electrode (not coated with a sulfonic acid COF membrane). The rest of the preparation method and raw materials are the same as those of the aqueous zinc battery B of Example 2.

[0061] (III) Example 3 and Comparative Example 3: (1) Example 3: ① Preparation of zinc electrode coated with sulfonic acid COF membrane: According to the following preparation method of zinc electrode coated with sulfonic acid COF membrane, zinc electrode C with sulfonic acid COF membrane is prepared: Step S1, dissolving 6.0 mg of 2,4,6-triformylphloroglucinol and 22.8 mg of p-phenylenediamine-2,5-disulfonic acid in 80 mL of N,N-dimethylformamide to obtain a mixed solution; Step S11, subjecting the mixed solution to ultrasonic treatment for 12 minutes; Step S2, polishing the zinc foil using 2000 mesh and 5000 mesh sandpaper in sequence, wherein the thickness of the zinc foil after polishing is in the range of 0.1 mm, and rinsing the polished zinc foil with anhydrous ethanol and deionized water twice in sequence, placing the polished and rinsed zinc foil in the mixed solution, and sealing and standing at room temperature for 1 day to coat the surface of the zinc foil with a sulfonic acid COF film; Step S3: Take out the zinc foil coated with the sulfonic acid COF film, rinse it with anhydrous ethanol and deionized water in sequence, and dry it at a drying temperature of 75° C. and a drying time of 2 h to obtain a zinc electrode C coated with the sulfonic acid COF film.

[0062] ② Using the zinc electrode C coated with the sulfonic acid COF film to prepare an aqueous zinc battery C: Assemble in a 2032-type button battery case (including a positive electrode case and a negative electrode case), with the corresponding assembly order being positive electrode case, positive electrode, separator, zinc sulfate electrolyte (the content of zinc sulfate electrolyte is 120 μL), negative electrode, gasket, spring and negative electrode case; The negative electrode is the prepared zinc electrode C coated with the sulfonic acid COF membrane, the positive electrode is a copper electrode, the diameter of each electrode is 12 mm, and the separator is a glass fiber separator. After assembly, an aqueous zinc battery C (the aqueous zinc battery C is a functional button asymmetric battery) can be obtained. The assembled aqueous zinc battery C is placed in a button battery sealing machine for pressure sealing and then left to stand for 12 hours for electrochemical performance testing.

[0063] (2) Comparative Example 3: Aqueous zinc battery F was prepared using the commercial zinc electrode (Bare Zn) used in Comparative Example 1: The difference between the aqueous zinc battery F of comparative example 3 and the aqueous zinc battery C of example 3 is that the negative electrode of the aqueous zinc battery F is a commercial zinc electrode (not coated with a sulfonic acid COF membrane), and the rest of the preparation method and raw materials are the same as those of the aqueous zinc battery C of example 3.

[0064] (IV) Performance testing and analysis: (1) The performance of the zinc electrode A (COF-Zn) coated with the sulfonic acid COF film prepared in Example 1 and the commercial zinc electrode (Bare Zn) of Comparative Example 1 were tested: ① Use the DSA100 contact angle meter produced by Dataphysics of Germany to measure the interface wettability. The test results are as follows: Figure 5As shown, the contact angle between the zinc electrode A coated with the sulfonic acid COF film and the electrolyte is 44.99°, and the contact angle between the commercial zinc electrode and the electrolyte is 93.57°. It can be obtained that the contact angle between the zinc electrode A coated with the sulfonic acid COF film and the electrolyte is smaller, indicating that the zinc electrode coated with the sulfonic acid COF film prepared by the present invention has better interface wetting ability.

[0065] ② The zinc electrode A (COF-Zn) coated with the sulfonic acid COF film prepared in Example 1 and the commercial zinc electrode (Bare Zn) of Comparative Example 1 were immersed in zinc sulfate electrolyte for 7 days, and the micromorphology of the COF-Zn and the Bare Zn before and after immersion for 7 days were observed using a TESCAN MIRA4 scanning electron microscope produced by Czech Tescan Co., Ltd. The test results are as follows: Figure 6 As shown (since the COF-Zn and the Bare Zn have no flaky dendrites before immersion, Figure 6 Only the result figure of Bare Zn before immersion is provided in the figure). Both the COF-Zn and the Bare Zn have no flaky dendrites before immersion, while the COF-Zn after immersion for 7 days has fewer flaky dendrites than the Bare Zn after immersion for 7 days, proving that the zinc electrode coated with sulfonic acid COF film prepared by the present invention has good dendrite suppression ability.

[0066] ③ The zinc electrode A (COF-Zn) coated with sulfonic acid COF film and the commercial zinc electrode (BareZn) of comparative example 1 were immersed in zinc sulfate electrolyte for 7 days, and then the surface composition of the COF-Zn and the Bare Zn after immersion for 7 days were scanned and analyzed using a DX-2700BH powder X-ray diffractometer produced by Dandong Haoyuan. The results are as follows: Figure 7 As shown, it can be seen that in terms of the intensity of the characteristic peak corresponding to ZnSO4·xH2O (hydrated zinc sulfate), the peak intensity of COF-Zn is significantly lower than the peak intensity of BareZn, indicating that the surface of the zinc electrode A coated with the sulfonic acid COF film has fewer by-products, that is, the zinc electrode A coated with the sulfonic acid COF film has fewer corrosion and passivation by-products, proving that the zinc electrode coated with the sulfonic acid COF film prepared by the present invention has good corrosion resistance.

[0067] (2) The aqueous zinc batteries A to C prepared in Examples 1 to 3 and the aqueous zinc batteries D to F prepared in Comparative Examples 1 to 3 were subjected to constant current charge and discharge and electrochemical performance tests using the Lanbo battery test system and the Chenhua electrochemical workstation. The specific test results and analysis are as follows: ① The aqueous zinc battery C prepared in Example 3 and the aqueous zinc battery F prepared in Comparative Example 3 were tested at 1 mA·cm -2, 1mAh·cm -2 The cycle performance test was carried out under the conditions and the coulomb efficiency of the two was compared. The results are as follows Figure 8 As shown in the graph, the coulombic efficiency cycle time of aqueous zinc battery C is much longer than that of aqueous zinc battery F, indicating that the aqueous zinc battery prepared by the present invention has better cycle reversibility.

[0068] ② The aqueous zinc battery B prepared in Example 2 and the aqueous zinc battery E prepared in Comparative Example 2 were tested at 1 mA·cm -2 , 1mAh·cm -2 The cycle performance test was carried out under the following conditions. The results are as follows Figure 9 As shown in the cyclic polarization voltage curve, by comparing the cycle life of the electrodes of the two, it can be seen that the cycle life of aqueous zinc battery B reaches 3000h, and the cycle life of aqueous zinc battery B is much higher than that of aqueous zinc battery E, indicating that the aqueous zinc battery prepared by the present invention has better battery cycle performance.

[0069] The thickness of the aqueous zinc battery B prepared in Example 2 and the aqueous zinc battery E prepared in Comparative Example 2 before cycling was measured, and the thickness of the aqueous zinc battery B and the aqueous zinc battery E after cycling was measured. The results are shown in Tables 1 and Figure 11 ( Figure 11 Only the thickness measurement results of aqueous zinc battery B before cycling are shown).

[0070] Table 1 Thickness measurement results of aqueous zinc batteries of Examples and Comparative Examples before and after cycling It should be noted that the change in battery thickness before and after cycling represents the intensity of the hydrogen evolution reaction. Figure 11 The results show that the thicknesses of the aqueous zinc battery B and the aqueous zinc battery E before cycling are 3.15 mm, respectively; the thickness of the aqueous zinc battery B after cycling is 3.28 mm; and the thickness of the aqueous zinc battery E after cycling is 4.38 mm. Compared with the thickness of the aqueous zinc battery B before cycling, the thickness of the aqueous zinc battery B after cycling is lower, indicating that its hydrogen evolution reaction is less, indicating that the aqueous zinc battery prepared by the present invention has better cycling capacity.

[0071] ③ The aqueous zinc battery A prepared in Example 1 and the aqueous zinc battery D prepared in Comparative Example 1 were tested at 1 mA·cm -2 , 1mAh·cm -2 The full battery charge and discharge performance test was carried out under the conditions to compare the battery capacity retention of the two. The results are as follows Figure 10As shown, the two curves at the top represent the coulombic efficiency curves of aqueous zinc battery A and aqueous zinc battery D, respectively, and the two curves at the bottom represent the specific capacity-voltage cycle curves of aqueous zinc battery A and aqueous zinc battery D. Compared with aqueous zinc battery D, aqueous zinc battery A has higher specific capacity and capacity retention rate during stable cycling, indicating that the aqueous zinc battery prepared by the present invention has better battery cycling performance.

[0072] Based on the above test results, the preparation method of the zinc electrode coated with sulfonic acid COF film of the present invention uses the 2,4,6-triformyl phloroglucinol and the p-phenylenediamine-2,5-disulfonic acid as precursors. At room temperature and in a closed environment, the hydroxyl groups in the 2,4,6-triformyl phloroglucinol and the amino groups in the p-phenylenediamine-2,5-disulfonic acid will spontaneously undergo dehydration condensation to form a chemical bond, so that the outer surface of the zinc electrode coated with the sulfonic acid COF film is covered with a sulfonic acid COF film having an ordered pore structure; the zinc electrode coated with the sulfonic acid COF film serves as the When the negative electrode of the aqueous zinc battery is used, the pore structure on the surface of the sulfonic acid COF membrane increases the specific surface area of the negative electrode interface. At the same time, the nitrogen, oxygen and other elements contained in the sulfonic acid COF membrane are conducive to the formation of hydrogen bonds, thereby increasing the affinity of the negative electrode interface to the zinc sulfate electrolyte and improving the wetting degree of the negative electrode surface. The good interface wetting ability can enable zinc ions to be transmitted faster during the charge and discharge process of the aqueous zinc battery, which helps to improve the charge and discharge efficiency and battery capacity retention rate of the aqueous zinc battery, extend the cycle life of the aqueous zinc battery, and improve the cycle stability.

[0073] In addition, the pore structure can inhibit the diffusion of water molecules to the negative electrode interface and exclude sulfate ions and other anions from the pore structure, thereby reducing the contact between water molecules and the negative electrode surface, thereby inhibiting hydrogen evolution and oxygen absorption corrosion reactions; in addition, the sulfonic acid sites attached to the inside of the pore structure are zinc-philic sites (sulfonic acid groups can strongly interact with zinc ions, reduce the coordinated water of zinc ions, and accelerate the transmission of zinc ions in the pore structure to the negative electrode surface), the pore structure and the sulfonic acid sites can guide zinc ions to deposit uniformly and rapidly on the surface of the negative electrode, so that the deposited zinc on the surface of the negative electrode achieves the purpose of dense and flat quality, thereby realizing the desolvation and rapid transmission of zinc ions, and helping to inhibit dendrite growth, reduce corrosion and passivation by-products. The prepared zinc electrode coated with the sulfonic acid COF film has good corrosion resistance and dendrite inhibition ability, which helps to improve the cycle performance of the aqueous zinc battery and extend the cycle life of the aqueous zinc battery. This can solve the problems of the zinc negative electrode of the existing aqueous zinc ion battery being prone to generate dendrites, corrosion and passivation side reactions during the battery cycle, which leads to reduced battery performance and short service life.

[0074] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a zinc electrode coated with a sulfonic acid COF film, characterized in that: The following steps are involved: Step S1, dissolving 2,4,6-triformylphloroglucinol and p-phenylenediamine-2,5-disulfonic acid in an organic solvent to obtain a mixed solution; Step S2, placing a zinc foil in the mixed solution, and allowing the mixture to stand in a sealed container at room temperature, so that the surface of the zinc foil is covered with a sulfonic acid COF film; Step S3: taking out the zinc foil coated with the sulfonic acid COF film, rinsing and drying it to obtain a zinc electrode coated with the sulfonic acid COF film.

2. The method for preparing a zinc electrode coated with a sulfonic acid COF film according to claim 1, characterized in that: The mass ratio of the added amounts of the 2,4,6-triformylphloroglucinol and the p-phenylenediamine-2,5-disulfonic acid is 1:2~3.8; the organic solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

3. The method for preparing a zinc electrode coated with a sulfonic acid COF film according to claim 1, characterized in that: The following steps are also included between step S1 and step S2: S11, performing ultrasonic treatment on the mixed solution.

4. The method for preparing a zinc electrode coated with a sulfonic acid COF film according to claim 1, characterized in that: In step S2, the zinc foil needs to be polished before being placed in the mixed solution. The polished zinc foil is rinsed with anhydrous ethanol and deionized water and then placed in an acetone solution for standby use.

5. The method for preparing a zinc electrode coated with a sulfonic acid COF film according to claim 1, characterized in that: In step S2, the sealed container is kept at room temperature for 1 to 5 days.

6. The method for preparing a zinc electrode coated with a sulfonic acid COF film according to claim 1, characterized in that: In step S3, the zinc foil coated with the sulfonic acid COF film is rinsed with anhydrous ethanol and deionized water in sequence and then dried. The drying temperature is 65° C. to 80° C., and the drying time is 1 hour to 2 hours.

7. A zinc electrode coated with a sulfonic acid COF film, characterized in that: The zinc electrode is prepared by the preparation method of the zinc electrode coated with a sulfonic acid COF film according to any one of claims 1 to 6.

8. An aqueous zinc battery, characterized in that: It comprises the zinc electrode piece coated with the sulfonic acid COF membrane as claimed in claim 7, wherein the negative electrode of the aqueous zinc battery is the zinc electrode piece coated with the sulfonic acid COF membrane.

9. The aqueous zinc ion battery according to claim 8, characterized in that The positive electrode of the aqueous zinc battery is one of a manganese dioxide electrode, a copper electrode, a stainless steel electrode or another zinc electrode coated with a sulfonic acid COF film.

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