Aqueous zinc negative electrode in-situ interface modification method and application of aqueous zinc negative electrode in battery

Abstract

The invention relates to the technical field of water-based zinc ion batteries, and discloses a water-based zinc negative electrode in-situ interface modification method and application in a battery, the method is characterized in that an in-situ organic acid ionic coupling interface film is constructed on the surface of a zinc sheet, and the film and the zinc sheet synergistically form a modified zinc negative electrode; the organic acid and metal ions can construct a highly stable metal-organic complex and chelate system, an interfacial film with a compact structure is generated in situ on the zinc negative electrode, the modified interface can effectively accelerate Zn < 2 + > diffusion kinetics, uniform nucleation and efficient deposition of Zn < 2 + > are ensured, H2 release is effectively inhibited, polarization and hydrogen evolution corrosion side reactions are remarkably reduced, and the electrochemical performance of the zinc negative electrode is improved. And particularly, the preparation process of the modified zinc negative electrode is simple and easy to operate, low in cost, extremely short in manufacturing time and beneficial to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of aqueous zinc-ion battery technology, specifically to an in-situ interface modification method for aqueous zinc anodes and its application in batteries. Background Technology

[0002] Currently, lithium metal batteries are the most widely used commercially available batteries. However, given the scarcity of lithium metal reserves, high price, and poor safety performance, exploring new battery technologies has become an inevitable trend. Zinc metal batteries, with their significant advantages such as considerable theoretical capacity, suitable redox potential, abundant natural reserves, good environmental compatibility, and relatively low cost, show great promise for energy storage. However, zinc-ion batteries still face many obstacles in their commercialization process, such as dendrite growth in the zinc anode, hydrogen evolution reaction, corrosion, and passivation challenges. Therefore, developing a simple and effective modified zinc anode to overcome these existing problems is crucial and of great significance. Summary of the Invention

[0003] The purpose of this invention is to solve the problems of dendrite growth, hydrogen evolution reaction, corrosion, and passivation in zinc anodes, and to propose an in-situ interface modification method for aqueous zinc anodes and its application in batteries.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A method for in-situ interface modification of aqueous zinc anodes includes the following steps: Step 1: Prepare an aqueous solution of tea polyphenols and stir well; Step 2: Grind the zinc sheet to remove the surface oxide layer, then wipe away the surface dust with a paper towel to obtain the pretreated zinc sheet; Step 3: Soak the pretreated zinc sheet in an aqueous solution of tea polyphenols to perform surface modification and obtain the soaked zinc sheet; Step 4: Rinse the soaked zinc sheet with deionized water and dry it to obtain the modified zinc anode.

[0005] Based on the above technical solution, the present invention can be further improved as follows.

[0006] Preferably, in step one, the concentration of the aqueous solution of tea polyphenols is 0.1~1 mol / L, and the water used to prepare the tea polyphenols is either deionized water or ultrapure water.

[0007] Preferably, the specific process of polishing in step two is to polish the zinc sheet sequentially with 1500-grit and 2500-grit sandpaper.

[0008] Preferably, step three is performed at room temperature and normal pressure for 5-10 minutes.

[0009] Preferably, the drying in step four is vacuum drying, which takes 2-24 hours and is carried out at a temperature of 30-80 degrees Celsius.

[0010] An application of an aqueous zinc anode in a battery, wherein the modified zinc anode is used in the preparation of an aqueous zinc-ion battery, wherein the aqueous zinc-ion battery is an aqueous zinc-ion symmetrical button cell or an aqueous zinc-ion button full cell.

[0011] Preferably, when preparing an aqueous zinc-ion symmetric button battery using a modified zinc negative electrode, the manufacturing steps are as follows: the modified zinc sheet is used as the positive and negative electrodes, and assembled with a separator and electrolyte to form an aqueous zinc-ion symmetric button battery, which is then left to stand for 2-24 hours.

[0012] Preferably, when preparing an aqueous zinc-ion button cell with a modified zinc anode, the manufacturing steps are as follows: select a positive electrode active material, mix it with conductive carbon black, binder and solvent to prepare a slurry, and coat it on a current collector. After drying, a positive electrode is obtained. The positive electrode, separator, modified zinc anode and electrolyte are assembled into an aqueous zinc-ion button cell.

[0013] Preferably, the solute in the electrolyte is ZnSO4 or ZnSO4+MnSO4, the concentration of the electrolyte is 2mol / L ZnSO4 or 2mol / L ZnSO4+0.1mol / L MnSO4, and the amount of electrolyte added to the diaphragm is 20-200 μL.

[0014] Preferably, the positive electrode active material is manganese dioxide; the current collector is carbon fiber cloth.

[0015] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: 1. Compared with existing technologies, this invention takes a unique approach by innovatively introducing a zinc-tea polyphenol chelate protective layer on the surface of the zinc anode. This chelate protective layer has high density and uniformity, which can effectively guide zinc ions to achieve uniform deposition and greatly inhibit dendrite growth. This protective layer can accurately occupy hydrogen evolution active sites, thereby forming a strong inhibitory effect on hydrogen evolution. It can also effectively block the direct contact path between water and zinc metal, thus significantly reducing the corrosive effect of water molecules on the zinc anode.

[0016] 2. The modified zinc anode preparation process adopted in this invention has significant advantages such as simple and convenient operation, low cost and short production cycle, which is extremely conducive to achieving the goal of large-scale production.

[0017] 3. This invention utilizes a zinc polyphenol protective layer to precisely regulate the zinc ion deposition state, successfully creating an excellent zinc anode with superior water corrosion resistance, no dendrite problems, and a long service life. This provides a strong impetus for the development of aqueous zinc-ion battery technology and offers a highly valuable solution. Attached Figure Description

[0018] Figure 1 This is a SEM image of the zinc sheet surface after grinding and cleaning in Embodiment 1 of the present invention; Figure 2 This is a SEM image of the modified zinc sheet after soaking in tea polyphenols for 5 minutes in Example 1 of the present invention; Figure 3 This is a SEM image of the zinc sheet surface after 30 cycles of a zinc / / zinc symmetric battery composed of zinc sheets soaked in tea polyphenols for 5 minutes in Example 1 of the present invention. Figure 4 This is a SEM image of the zinc sheet surface after 30 cycles of a zinc / / zinc symmetric battery composed of bare zinc in Comparative Example 1 of this invention; Figure 5 The time-voltage curves of symmetrical batteries in Embodiment 1 and Comparative Example 1 of the present invention, using unimmersed zinc sheets as positive and negative electrodes and modified zinc sheets as positive and negative electrodes, respectively; Figure 6 The cycling stability tests of zinc / manganese dioxide full cells using unmodified zinc sheets and modified zinc sheets as negative electrodes in Example 3 and Comparative Example 2 of this invention are presented. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The following specific embodiments and comparative examples further illustrate the essential features and significant advancements of the present invention, but the present invention is by no means limited to the examples described.

[0021] A method for in-situ interface modification of aqueous zinc anodes includes the following steps: Step 1: Prepare an aqueous solution of tea polyphenols and stir well; Step 2: Grind the zinc sheet to remove the surface oxide layer, then wipe away the surface dust with a paper towel to obtain the pretreated zinc sheet; Step 3: Soak the pretreated zinc sheet in an aqueous solution of tea polyphenols to perform surface modification and obtain the soaked zinc sheet; Step 4: Rinse the soaked zinc sheet with deionized water and dry it to obtain the modified zinc anode.

[0022] In step one, the concentration of the aqueous solution of tea polyphenols is 0.1~1 mol / L, and the water used to prepare the tea polyphenols is either deionized water or ultrapure water.

[0023] The specific process of polishing in step two involves polishing the zinc sheet sequentially with 1500-grit and 2500-grit sandpaper.

[0024] Step three is performed at room temperature and normal pressure for 5-10 minutes.

[0025] The drying process in step four is vacuum drying, which takes 2-24 hours and is carried out at a temperature of 30-80 degrees Celsius.

[0026] The modified zinc anode is used in the preparation of an aqueous zinc-ion battery, which is an aqueous zinc-ion symmetrical button cell or an aqueous zinc-ion button full cell.

[0027] When preparing an aqueous zinc-ion symmetric button cell using a modified zinc anode, the steps are as follows: the modified zinc sheet is used as both the positive and negative electrodes, and is assembled with a separator and electrolyte to form an aqueous zinc-ion symmetric button cell, which is then left to stand for 2-24 hours.

[0028] When preparing an aqueous zinc-ion button cell using a modified zinc anode, the steps are as follows: select a positive electrode active material, mix it with conductive carbon black, binder, and solvent to prepare a slurry, and coat it onto a current collector. After drying, a positive electrode is obtained. The positive electrode, separator, modified zinc anode, and electrolyte are then assembled into an aqueous zinc-ion button cell.

[0029] The solute in the electrolyte is ZnSO4 or ZnSO4+MnSO4, the concentration of the electrolyte is 2mol / L ZnSO4 or 2mol / L ZnSO4+0.1mol / L MnSO4, and the amount of electrolyte added to the diaphragm is 20-200 μL.

[0030] The positive electrode active material is manganese dioxide; the current collector is carbon fiber cloth, model WOS1002 or WOS1005.

[0031] Example 1 Step 1: Prepare a 0.5 mol / L tea polyphenol aqueous solution, stir well and set aside for use; Step 2: Polish the zinc sheet with 1500-grit and 2500-grit sandpaper in turn, and then wipe off the surface dust with a paper towel to obtain the pre-treated zinc sheet; like Figure 1 As shown, the zinc sheet surface is relatively flat; Step 3: Soak the pretreated zinc sheet in an aqueous solution of tea polyphenols for 5 minutes to modify its surface; Step 4: Rinse the zinc sheet soaked in Step 3 with deionized water, and then dry it to obtain the modified zinc sheet negative electrode; Figure 2 As shown, there is a noticeable additional layer of material on the surface of the zinc sheet compared to the pretreated sheet; Step 5: Select the modified zinc sheet as the positive and negative electrodes, and assemble it with the separator and 180 μL of 2 mol / L zinc sulfate electrolyte to form an aqueous zinc-ion symmetric battery. Let it stand for 8 hours.

[0032] After 30 charge-discharge cycles, such as Figure 3 As shown, after 30 charge-discharge cycles, the modified zinc sheet exhibits uniform zinc deposition on its surface without zinc dendrites.

[0033] Example 2 Step 1: Prepare a 0.5 mol / L tea polyphenol aqueous solution, stir well and set aside for use; Step 2: Polish the zinc sheet with 1500-grit and 2500-grit sandpaper in turn, and then wipe off the surface dust with a paper towel to obtain the pre-treated zinc sheet; Step 3: Soak the pretreated zinc sheet in an aqueous solution of tea polyphenols for 10 minutes to modify its surface; Step 4: Wash the zinc sheet soaked in Step 3 with deionized water, and then dry it to obtain the modified zinc sheet negative electrode; Step 5: Select modified zinc sheets as the positive and negative electrodes, and assemble them with a separator and 180 μL of 2M zinc sulfate electrolyte to form an aqueous zinc-ion symmetric battery. Let it stand for 8 hours.

[0034] Select a current density of 5 mA / cm² 2 With a bulk density of 5 mA / cm³ 2 Perform constant current charge-discharge testing. For example... Figure 5 As shown, a symmetrical battery composed of modified zinc sheets can cycle stably for more than 300 hours.

[0035] Example 3 Step 1: Prepare a 0.5 mol / L tea polyphenol aqueous solution, stir well and set aside for use; Step 2: Polish the zinc sheet with 1500-grit and 2500-grit sandpaper in turn, and then wipe off the surface dust with a paper towel to obtain the pre-treated zinc sheet; Step 3: Soak the pretreated zinc sheet in an aqueous solution of tea polyphenols for 5 minutes to modify its surface; Step 4: Wash the zinc sheet soaked in Step 4 with deionized water, and then dry it to obtain the modified zinc sheet negative electrode; Step 5: Mix the active material MnO2 with the binder PVDF and conductive carbon black Super P in NMP solvent, and coat it onto the carbon cloth current collector. After drying, the positive electrode is obtained. Step 5: Modified zinc sheet was selected as the negative electrode and assembled with a separator and 180 μL of 2 mol / L zinc sulfate electrolyte to form an aqueous zinc-ion full cell. The cell was then allowed to stand for 8 hours. A long-term constant current charge-discharge test was conducted at a current density of 10 A / g.

[0036] like Figure 6 As shown, after 190 charge-discharge cycles, the discharge specific capacity of the full cell using the modified zinc anode reached 205 mAh·g. -1 .

[0037] Comparative Example 1 Half-cell comparison Step 1: Prepare a 0.5 mol / L tea polyphenol aqueous solution, stir well and set aside for use; Step 2: Polish the zinc sheet with 1500-grit and 2500-grit sandpaper in turn, and then wipe off the surface dust with a paper towel to obtain the pre-treated zinc sheet; Step 3: Select the pretreated zinc sheet as the positive and negative electrodes, and assemble it with the separator and 180 μL of 2 mol / L zinc sulfate electrolyte to form an aqueous zinc-ion symmetric battery. Let it stand for 8 hours.

[0038] Select a current density of 5 mA / cm² 2 With a bulk density of 5 mA / cm³ 2 Perform constant current charge-discharge testing. For example... Figure 5 As shown, the symmetric cell composed of pretreated zinc sheets experienced a short circuit after only 80 hours of cycling. In contrast, the symmetric cell composed of modified zinc sheets could cycle stably for over 300 hours, demonstrating a significant improvement in cycle life.

[0039] After 30 charge-discharge cycles, such as Figure 4 As shown, after 30 charge-discharge cycles, uneven zinc deposition and zinc dendrites appeared on the surface of the pretreated zinc sheet; as... Figure 3 As shown, after 30 charge-discharge cycles, the modified zinc sheet exhibits uniform zinc deposition on its surface without zinc dendrites.

[0040] Comparative Example 2 Full battery comparison Step 1: Prepare a 0.5 mol / L tea polyphenol aqueous solution, stir well and set aside for use; Step 2: Polish the zinc sheet with 1500-grit and 2500-grit sandpaper in turn, and then wipe off the surface dust with a paper towel to obtain the pre-treated zinc sheet; Step 3: Mix the active material MnO2 with the binder PVDF and conductive carbon black Super P in NMP solvent, and coat it onto the carbon cloth current collector. After drying, the positive electrode is obtained. Step 4: Select the pretreated zinc sheet as the negative electrode, and assemble it with the separator and 180 μL of 2 mol / L zinc sulfate electrolyte to form an aqueous zinc-ion full cell. Let it stand for 8 hours. Select a current density of 1 A / g for long-term constant current charge-discharge test.

[0041] like Figure 6 As shown, after 190 charge-discharge cycles, the discharge specific capacity of the full cell using the modified zinc anode reached 205 mAh·g. -1 The discharge specific capacity is 158 mAh·g compared to a full cell using an unmodified zinc anode. -1 There has been a significant improvement.

[0042] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for in-situ interface modification of aqueous zinc anodes, characterized in that, Includes the following steps: Step 1: Prepare an aqueous solution of tea polyphenols and stir well; Step 2: Grind the zinc sheet to remove the surface oxide layer, then wipe away the surface dust with a paper towel to obtain the pretreated zinc sheet; Step 3: Soak the pretreated zinc sheet in an aqueous solution of tea polyphenols to perform surface modification and obtain the soaked zinc sheet; Step 4: Rinse the soaked zinc sheet with deionized water and dry it to obtain the modified zinc anode.

2. The method for in-situ interface modification of aqueous zinc anode according to claim 1, characterized in that: In step one, the concentration of the aqueous solution of tea polyphenols is 0.1~1 mol / L, and the water used to prepare the tea polyphenols is either deionized water or ultrapure water.

3. The method for in-situ interface modification of aqueous zinc anode according to claim 1, characterized in that: The specific process of polishing in step two involves polishing the zinc sheet sequentially with 1500-grit and 2500-grit sandpaper.

4. The method for in-situ interface modification of aqueous zinc anode according to claim 1, characterized in that: Step three is performed at room temperature and normal pressure for 5-10 minutes.

5. The method for in-situ interface modification of aqueous zinc anode according to claim 1, characterized in that: The drying process in step four is vacuum drying, which takes 2-24 hours and is carried out at a temperature of 30-80 degrees Celsius.

6. The application of the modified zinc anode prepared by the modification method according to any one of claims 1-5 in a battery, characterized in that, The modified zinc anode is used in the preparation of an aqueous zinc-ion battery, which is an aqueous zinc-ion symmetrical button cell or an aqueous zinc-ion button full cell.

7. The application of an aqueous zinc negative electrode in a battery according to claim 6, characterized in that: When preparing an aqueous zinc-ion symmetric button cell using a modified zinc anode, the steps are as follows: the modified zinc sheet is used as both the positive and negative electrodes, and is assembled with a separator and electrolyte to form an aqueous zinc-ion symmetric button cell, which is then left to stand for 2-24 hours.

8. The application of an aqueous zinc negative electrode in a battery according to claim 6, characterized in that: When preparing an aqueous zinc-ion button cell using a modified zinc anode, the steps are as follows: select a positive electrode active material, mix it with conductive carbon black, binder, and solvent to prepare a slurry, and coat it onto a current collector. After drying, a positive electrode is obtained. The positive electrode, separator, modified zinc anode, and electrolyte are then assembled into an aqueous zinc-ion button cell.

9. The application of an aqueous zinc negative electrode in a battery according to any one of claims 7 or 8, characterized in that: The solute in the electrolyte is ZnSO4 or ZnSO4 + MnSO4. 4， The concentration of the electrolyte is 2 mol / L ZnSO4 or 2 mol / L ZnSO4 + 0.1 mol / L ZnSO4, and the amount of electrolyte added to the diaphragm is 20-200 μL.

10. The application of an aqueous zinc negative electrode in a battery according to claim 8, characterized in that: The positive electrode active material is manganese dioxide; the current collector is carbon fiber cloth.

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