Preparation method of stable metal zinc negative electrode surface of beta-cyclodextrin modified polyion elastomer copolymer electrolyte membrane

Abstract

The invention discloses a method for preparing a stable metal zinc negative electrode surface of a beta-cyclodextrin modified polyion elastomer copolymer electrolyte membrane, which comprises the following steps of: preparing mixed slurry of a polyion elastomer and beta-cyclodextrin by taking metal zinc as a substrate through chemical polymerization and microphase separation strategies; a metal zinc substrate is uniformly coated with the obtained slurry, a copolymer electrolyte membrane is constructed on the surface of metal zinc, the obtained copolymer electrolyte membrane has the functions of corrosion protection, regulation and control of zinc ion transportation and inhibition of hydrogen evolution reaction, beta-cyclodextrin in the copolymer electrolyte membrane can provide an ion channel for zinc ions, a diffusion path can be standardized, and the service life of the electrolyte membrane is prolonged. And the mass transfer process is accelerated, and zinc ions are induced to horizontally deposit along the (002) crystal face. The beta-cyclodextrin modified polyion elastomer stabilized metal zinc negative electrode surface multifunctional copolymer electrolyte membrane disclosed by the invention has the physical properties of high breaking strength, high flexibility and good conductivity, and has a self-repairing function; and the internal ion grid structure can obviously prolong the cycle life of the zinc metal battery in an aqueous electrolyte.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc metal battery anode modification technology, specifically relating to a method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane to stabilize the surface of a metallic zinc anode. Background Technology

[0002] Energy is a vital material foundation for human survival and development, impacting national welfare, people's livelihoods, and national security. With the rapid development of intermittent energy sources such as solar and wind power, developing efficient energy storage systems to achieve large-scale storage and transportation of these energy sources has become a crucial challenge for humanity. Among various energy storage systems, aqueous zinc-ion batteries (AZIBs) utilize aqueous solutions as the electrolyte, offering significantly higher safety compared to flammable organic electrolytes. Furthermore, metallic zinc is cost-effective (giant Earth's zinc reserves are abundant) and has a theoretically high specific capacity (820 mAh·g⁻¹). -1 Or 5855 mAh·cm -3 Zinc anodes, with their advantages such as low redox potential (-0.76 V compared to standard hydrogen electrodes), are considered ideal replacements for next-generation energy storage batteries. However, zinc anodes suffer from problems such as excessive dendrite growth, hydrogen evolution reaction (HER), surface corrosion passivation, and poor high-current stability, which seriously affect battery cycle life and become a bottleneck restricting the further development and application of AZIBs. To date, numerous methods have been explored to overcome the aforementioned problems faced by zinc anodes, primarily including: improvements to the zinc anode substrate material, the construction of artificial solid electrolyte interfaces (ASEIs), membrane modification, and electrolyte optimization. Among these approaches, the construction of ASEIs has become a research hotspot. This is mainly because zinc anode corrosion, HER (hydrothermal erosion), and dendrite formation all occur at the electrolyte / electrode interface, making the construction of a protective coating at this interface an effective strategy for addressing these issues. Studies have shown that by optimizing the composition and process of the protective coating, the performance and cycle life of AZIBs are continuously being improved. Based on the above analysis, this invention constructs a β-cyclodextrin-modified polyionic elastomer coating on the surface of the zinc anode, which has both ion transport and protection functions. By combining hydrophobic interactions with electrostatic interactions, a solvent-free transparent poly(ionic liquid) elastomer (PILE) coating system prepared using acrylate monomers and ionic liquids is obtained to inhibit zinc anode corrosion, HER, and dendrite formation. At the same time, the introduction of β-cyclodextrin adds zinc ion diffusion channels inside the polyionic elastomer coating, promotes the planar growth of zinc dendrites and the rapid desolvation and diffusion of zinc ions, thereby improving the service life of the zinc anode and the cycle stability under high current density. Summary of the Invention

[0003] This invention addresses the problems of excessive dendrite growth, hydrogen evolution reaction, surface corrosion and passivation, and poor high-current stability in aqueous zinc-ion batteries' zinc anodes during charge and discharge. It provides a method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane to stabilize the surface of the zinc anode. This process is simple, environmentally friendly, and yields an interface layer with good adhesion, high ion mobility, and excellent dendrite suppression properties, thereby achieving long-term protection for the zinc anode and improving its stability and lifespan during aqueous battery cycling. Technical solution

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a zinc metal anode includes the following steps: Step 1: Mix lithium bis(trifluoromethanesulfonyl)imide, acryloyloxyethyltrimethylammonium chloride and deionized water, and stir the mixture. Step 2: Wash the sample stirred in Step 1 with water to separate it into layers, and then enrich it to obtain the lower ionic liquid. Step 3: Place the ionic liquid obtained in Step 2 in a vacuum oven to dry it; Step 4: Mix the dried ionic liquid from Step 3 with butyl acrylate and azobisisobutyronitrile, and stir the mixture. Step 5: Place the stirred sample from Step 4 in a vacuum oven for thermal polymerization to obtain a polyionomer; Step 6: Dissolve the polyionic elastomer obtained in step 5 in acetone, then add β-cyclodextrin and mix. After sonicating the mixture, a copolymer electrolyte coating with stable zinc anode surface is obtained. Step 7: The copolymer electrolyte coating obtained in Step 6 is uniformly coated onto a clean zinc substrate and allowed to air dry naturally to obtain a copolymer electrolyte film with a uniform surface. Furthermore, in step 1, the ratio of lithium bis(trifluoromethanesulfonyl)imide, acryloyloxyethyltrimethylammonium chloride, and deionized water is 16 mmol: 19 mmol: 50 ml, the stirring time is 24 h, and the stirring speed is 150 r / min. Furthermore, in step 2, the sample is washed with water using a separatory funnel, with 50 ml of deionized water used each time, and the operation is repeated five times. Furthermore, in step 3, the temperature of the vacuum oven is 80 ℃ and the time is 24 h. Furthermore, in step 4, the ratio of ionic liquid to butyl acrylate and azobisisobutyronitrile is 4 mmol: 12 mmol: 0.2 mmol, the stirring time is 10 min, and the stirring speed is 150 r / min. Furthermore, in step 5, the temperature of the vacuum oven is 60 ℃ and the time is 24 h. Furthermore, in step 6, the ratio of polyionic elastomer to acetone to β-cyclodextrin is 4.8 mmol: 10 ml: 0.13 mmol, the ultrasonic power is 100 W, the temperature is controlled at 25 ℃, and the time is 10 min. Furthermore, in step 7, the zinc purity in the zinc substrate is 95%, the zinc substrate is a zinc sheet, and the thickness of the zinc substrate is 50 μm. Furthermore, the coating method in step 7 is blade coating, and the coating thickness is between 500 nm and 1000 nm. Furthermore, in step 7, the room temperature environment for natural air drying is 27 ℃, and the time is 24 h. Explanation of the principle: This invention uses acryloyloxyethyltrimethylammonium bis(trifluoromethanesulfonyl)imide and butyl acrylate as comonomers. The resulting copolymeric ionic elastomer consists of random soft butyl acrylate segments and hard polyacryloyloxyethyltrimethylammonium bis(trifluoromethanesulfonyl)imide segments. The cations are fixed on a stretchable elastic network, while the anions are mobile. This ionic bond also plays a role in promoting zinc ion transport, mainly due to the internal mobile anions attracting zinc ions and increasing their transport rate within the coating. β-Cyclodextrin, through its unique hydrophobic cavities and hydrophilic surfaces, regulates the solvation structure of zinc ions, accelerating the desolvation process of hydrated zinc ions, thereby enhancing zinc deposition kinetics and suppressing side reactions. In addition, β-Cyclodextrin can also provide ion channels for zinc ions, regulate diffusion paths, and promote horizontally oriented deposition. Beneficial effects: 1. In addressing the problems of excessive dendrite growth, hydrogen evolution reaction, surface corrosion and passivation, and poor high-current stability in zinc anodes, this invention uses inexpensive, high-performance polymer monomer butyl acrylate as a raw material and introduces low-cost, non-toxic β-cyclodextrin to improve the performance of the copolymer electrolyte membrane, effectively improving the cycle life of zinc-ion batteries and increasing the feasibility of industrial production. 2. The zinc anode prepared in this invention operates at a current density of 1 mA·cm⁻¹. -2 The surface capacity is 1 mAh·cm -2 In symmetrical batteries, the working life can reach more than 5,000 hours, extending the life of zinc-ion batteries by nearly 10 times; 3. The zinc anode prepared by this invention operates at a current density of 1 mA·cm⁻¹. -2 The surface capacity is 1 mAh·cm -2In the PILE@CD-Cu / / Zn asymmetric cell, the cycle life can reach more than 900 cycles, and the coulombic efficiency is as high as 99.66%; 4. The zinc anode prepared by this invention operates at a current density of 10 mA·cm⁻¹. -2 The surface capacity is 10 mAh·cm -2 In symmetrical batteries, the working life can reach more than 1,000 hours, extending the life of zinc-ion batteries by nearly 20 times. Attached Figure Description Figure 1 This is a diagram illustrating the mechanism of action of the β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane on the zinc anode in this invention. Figure 2 Stress-strain curves of β-cyclodextrin-modified polyionic elastomer copolymers in this invention; Figure 3 Microscopic morphology of the β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane on the zinc anode surface in this invention; Figure 4 Puncture stress test of β-cyclodextrin modified polyionic elastomer copolymer electrolyte membrane on zinc anode surface in this invention; Figure 5 The current density in this invention is 1 mA·cm -2 The surface capacity is 1 mAh·cm -2 A comparison of the charge-discharge cycle performance of symmetrical batteries; Figure 6 The current density in this invention is 10 mA·cm -2 The surface capacity is 10 mAh·cm -2 A comparison of the charge-discharge cycle performance of symmetrical batteries; Figure 7 The current density in this invention is 1 mA·cm -2 The surface capacity is 1 mAh·cm -2 A comparison chart of the charge-discharge cycle performance of zinc-copper batteries. Detailed Implementation The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1 A method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane to stabilize the surface of a zinc metal anode (mechanism diagram shown). Figure 1 (As shown), including the following steps: Step 1: Mix 4.534 g of lithium bis(trifluoromethanesulfonyl)imide, 3.6376 g of acryloyloxyethyltrimethylammonium chloride and 50 ml of deionized water. Stir the mixture for 24 h at a speed of 150 r / min. Step 2: Wash the sample stirred in Step 1 with water using a separatory funnel to separate the layers and enrich the lower oil phase. Repeat this operation five times to obtain a more enriched ionic liquid. Step 3: Place the ionic liquid obtained in Step 2 in a vacuum oven and dry it at 80 °C for 24 h; Step 4: Take 1.752 g of the dried ionic liquid from Step 3, mix it with 1.536 g of butyl acrylate and 0.033 g of azobisisobutyronitrile, and stir the mixture for 10 min at a speed of 150 r / min. Step 5: Place the stirred sample from Step 4 in a vacuum oven at 60 °C for thermal polymerization for 24 h to obtain a polyionomer. The stress-strain curve is shown below. Figure 2 As shown; Step 6: Dissolve 5.53 g of the polyionic elastomer obtained in Step 5 in 10 ml of acetone, then add 0.15 g of β-cyclodextrin and mix. After sonicating the mixture for 10 min, a copolymer electrolyte coating with stable zinc anode surface is obtained. Step 7: The copolymer electrolyte coating obtained in Step 6 is uniformly coated onto a clean zinc substrate and allowed to air dry for 24 hours to obtain a uniform copolymer electrolyte film. The microstructure is shown in the figure below. Figure 3 As shown, the puncture stress test of the copolymer electrolyte membrane is as follows: Figure 4 As shown. Example 2 Cyclic testing of a symmetric battery with a zinc anode modified by a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane. The zinc anode modified by the copolymer electrolyte membrane prepared in Example 1 was used to assemble a symmetric battery. The specific experimental steps are as follows: Step 1, place two pieces with an area of ​​1.13 cm² -2 Circular titanium meshes are neatly stacked inside the battery casing, and then a 1.13 cm² area is formed. -2 A round pure zinc foil is gently placed on a titanium mesh; Step 2, with an area of ​​1.77 cm -2 A circular glass fiber diaphragm is placed directly above a pure zinc foil, and an appropriate amount of 2M zinc sulfate solution is dripped in to completely wet the diaphragm. Step 3: Place the zinc negative electrode sheet modified with copolymer electrolyte membrane in the center of the separator, cover it with the battery case, and perform the encapsulation operation through the battery encapsulation machine to assemble it into a CR2016 button cell, denoted as PILE@CD-Zn / / Zn button cell; Step 4: Perform charge-discharge cycle tests on the button battery assembled in Step 3 using the Blue Electric monitoring system, setting the current density to 1 mA·cm⁻¹. -2 The surface capacity is 1 mAh·cm -2 and current density of 10 mA·cm -2 The surface capacity is 10mAh·cm³. -2 Two testing schemes. like Figure 5 As shown, at a current density of 1 mA·cm -2 The surface capacity is 1 mAh·cm -2 In the comparison chart of symmetrical battery charge-discharge cycle performance, the working life can reach more than 5,000 hours, extending the life of zinc-ion batteries by nearly 10 times. like Figure 6 As shown, at a current density of 10 mA·cm -2 The surface capacity is 10 mAh·cm -2 In the comparison chart of the charge-discharge cycle performance of symmetrical batteries, the working life can reach 1000 hours, which extends the life of zinc-ion batteries by nearly 20 times. Example 3 Cyclic testing of an asymmetric battery with a zinc anode modified by a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane: The specific experimental steps are as follows: Step 1: The copolymer electrolyte slurry on the surface of the stable zinc negative electrode prepared in Example 1 is coated evenly on the bare copper foil by a scraping method using a scraping device. The coating thickness is 1 μm. After air drying at room temperature for 24 h, the copper positive electrode sheet modified with copolymer electrolyte membrane can be obtained. Step 2, place the two pieces with an area of ​​1.13 cm² -2 Circular titanium meshes are neatly stacked inside the battery casing, and then a 1.13 cm² area is formed. -2 A copper positive electrode sheet modified with a copolymer electrolyte membrane is gently placed on a titanium mesh; Step 3, with an area of ​​1.77 cm -2 A circular glass fiber diaphragm is placed directly above a pure zinc foil, and an appropriate amount of 2M zinc sulfate solution is dripped in to completely wet the diaphragm. Step 4: Place the zinc negative electrode sheet modified with copolymer electrolyte membrane in the center of the separator, cover it with the battery case, and perform the encapsulation operation through the battery encapsulation machine to assemble it into a CR2016 button cell, denoted as PILE@CD-Cu / / Zn button cell. Step 5: Perform a charge-discharge cycle test on the Blue Electric monitoring system using the button battery assembled in Step 4, setting the current density to 1 mA·cm⁻¹. -2 The surface capacity is 1 mAh·cm -2 The test plan. like Figure 7 As shown, at a current density of 1 mA·cm -2 The surface capacity is 1 mAh·cm -2 Under these conditions, the coulombic efficiency of the PILE@CD-Cu / / Zn asymmetric cell after 900 cycles can reach 99.66%. The embodiments selected in the above materials are for ease of understanding and not for limiting the process method. Those skilled in the art can easily modify the process flow or transfer it to other cases without inventive change. If these modifications also fall under the category of similar claims or similar technology of this invention, then the intent of this invention also includes these modifications.

Claims

1. A method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode, characterized in that, Specifically, the steps include the following: Step 1: Mix lithium bis(trifluoromethanesulfonyl)imide, acryloyloxyethyltrimethylammonium chloride and deionized water, and stir the mixture. Step 2: Wash the sample stirred in Step 1 with water to separate it into layers, and then enrich it to obtain the lower ionic liquid. Step 3: Place the ionic liquid obtained in Step 2 in a vacuum oven to dry it; Step 4: Mix the dried ionic liquid from Step 3 with butyl acrylate and azobisisobutyronitrile, and stir the mixture. Step 5: Place the stirred sample from Step 4 in a vacuum oven for thermal polymerization to obtain a polyionomer; Step 6: Dissolve the polyionic elastomer obtained in step 5 in acetone, then add β-cyclodextrin and mix. After sonicating the mixture, a copolymer electrolyte coating with stable zinc anode surface is obtained. Step 7: The copolymer electrolyte coating obtained in Step 6 is uniformly coated onto a clean zinc substrate and allowed to air dry naturally to obtain a copolymer electrolyte film with a uniform surface.

2. The method for preparing the β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 1, the ratio of lithium bis(trifluoromethanesulfonyl)imide, acryloyloxyethyltrimethylammonium chloride, and deionized water was 16 mmol: 19 mmol: 50 ml, the stirring time was 24 h, and the stirring speed was 150 r / min.

3. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 2, the sample is washed with water using a separatory funnel, with 50 ml of deionized water used each time, and the operation is repeated five times.

4. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 3, the temperature of the vacuum oven is 80 ℃ and the time is 24 h.

5. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 4, the ratio of ionic liquid to butyl acrylate and azobisisobutyronitrile is 4 mmol: 12 mmol: 0.2 mmol, the stirring time is 10 min, and the stirring speed is 150 r / min.

6. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 5, the temperature of the vacuum oven is 60 ℃ and the time is 24 h.

7. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 6, the ratio of polyionic elastomer to acetone and β-cyclodextrin was 4.8 mmol:10 ml:0.13 mmol. The ultrasonic power was 100 W, the temperature was controlled at 25 ℃, and the time was 10 min.

8. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 7, the zinc purity in the zinc substrate is 95%, the zinc substrate is a zinc sheet, and the thickness of the zinc substrate is 50 μm.

9. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, The coating method in step 7 is blade coating, and the coating thickness is between 500 nm and 1000 nm.

10. The method for preparing a β-cyclodextrin-modified polyionic elastomer copolymer electrolyte membrane for stabilizing the surface of a metallic zinc anode according to claim 1, characterized in that, In step 7, the room temperature for natural air drying is 27 ℃, and the time is 24 h.

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