A polyzwitterionic hydrogel electrolyte, and a preparation method and application thereof

Abstract

The application relates to the technical field of zinc ion hybrid supercapacitors, in particular to a polyampholyte hydrogel electrolyte and a preparation method and application thereof. A monomer solution is obtained by dissolving sodium methallyl sulfonate, sodium acrylate and N-hydroxymethyl acrylamide in water; a quaternary ammonium salt chitosan is used as a cationic modifier, N,N'-ethylene bisacrylamide is used as a crosslinking agent, and the monomer solution, the cationic modifier and the crosslinking agent are subjected to free radical polymerization under the action of a photoinitiator to obtain a polyampholyte hydrogel, and then the polyampholyte hydrogel is subjected to drying treatment to obtain a polyampholyte porous hydrogel; the polyampholyte porous hydrogel is immersed in a glycol aqueous solution of a soluble zinc salt, and is left to stand until the volume does not change any more, so that the polyampholyte hydrogel electrolyte is obtained. The polyampholyte hydrogel electrolyte can not only effectively inhibit the growth of zinc ion dendrites, but also significantly improve the coulombic efficiency and cycle life of a zinc ion hybrid supercapacitor.

Description

Technical Field

[0001] This invention relates to the field of zinc ion hybrid supercapacitor technology, specifically to a polyzwitterionic hydrogel electrolyte, its preparation method, and its application. Background Technology

[0002] Supercapacitors, due to their rapid charge / discharge rates, high power density, wide operating temperature range, and ultra-long lifespan, have become indispensable electrochemical energy storage devices in consumer electronics, transportation, and power systems. With the increasing demand for electrochemical energy storage devices from portable electronic devices and electric vehicles, traditional batteries and hybrid supercapacitors face several safety and cost challenges. The high reactivity of lithium, sodium, and potassium alkali metals, along with the flammability of the electrolyte, poses significant safety hazards. Furthermore, the scarcity and uneven distribution of lithium resources exacerbate cost issues. Against this backdrop, electrochemical energy storage systems based on multivalent metal ions have been proposed and applied to the design of novel electrochemical energy storage devices. These multivalent metal ions (such as Zn...) 2+ Mg 2+ Ca 2+ And Al 3+ Compared to monovalent metal ions (such as Li), + Na + K + The battery system has higher capacity, energy density and faster charge transfer kinetics.

[0003] With the rapid development of emerging electronic devices, flexible energy storage devices with high energy density, high power density, and excellent safety have been extensively studied. Zinc-ion hybrid supercapacitors combine the advantages of Faraday reaction-based battery systems with supercapacitor systems based on rapid ion adsorption-desorption mechanisms, exhibiting high energy density and excellent power density characteristics. In recent years, hydrogel electrolytes used in zinc-ion hybrid supercapacitors have become a research focus in this field, mainly due to their excellent electrochemical performance, superior safety characteristics, and environmental friendliness. However, traditional hydrogel electrolytes still suffer from problems such as limited ion migration, dendrite growth, and capacity decay, restricting their application in zinc-ion hybrid supercapacitors. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a polyzwitterionic hydrogel electrolyte, its preparation method, and its applications. This invention uses sodium methacrylate sulfonate, sodium acrylate, and N-hydroxymethylacrylamide as functional monomer raw materials, quaternary ammonium salt chitosan as a cationic modifier, and N,N'-ethylenebisacrylamide as a crosslinking agent. Free radical polymerization is carried out in the presence of a photoinitiator to form a polyzwitterionic hydrogel. After drying, a porous polyzwitterionic hydrogel is obtained. Subsequently, the porous polyzwitterionic hydrogel is immersed in an aqueous solution of soluble zinc salt in ethylene glycol to obtain a polyzwitterionic hydrogel electrolyte with ordered ion channels. The polyzwitterionic hydrogel electrolyte prepared by the method of this invention not only achieves Zn 2+ The efficient directional migration and uniform deposition also significantly suppress dendrite growth and side reactions, overcoming the technical defects of existing zinc ion mixed supercapacitor electrolytes, such as limited ion migration, short cycle life and poor safety.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to provide a method for preparing a polyzwitterionic hydrogel electrolyte, comprising the following steps: S1. Preparation of the monomer solution for the zwitterionic hydrogel: Sodium methacrylate, sodium acrylate, and N-hydroxymethylacrylamide were dissolved together in water to obtain a monomer solution. Sodium methacrylate provides anionic sulfonic acid groups, constructs ordered zinc ion channels, and improves the ionic conductivity of the zwitterionic hydrogel electrolyte. Sodium acrylate improves the hydrophilicity and flexibility of the zwitterionic hydrogel through its carboxyl structure, has a stable microporous network, and forms an ion migration environment. N-hydroxymethylacrylamide, as a crosslinking monomer, enhances the overall mechanical properties and structural stability of the zwitterionic hydrogel.

[0006] S2. Preparation of polyzwitterionic porous hydrogel: Using quaternary ammonium salt chitosan as a cationic modifier and N,N'-ethylenebisacrylamide as a crosslinking agent, the monomer solution, cationic modifier and crosslinking agent are subjected to free radical polymerization under the action of photoinitiator to form polyzwitterionic hydrogel. After drying treatment, polyzwitterionic porous hydrogel is obtained.

[0007] S3. Preparation of the poly-zwitterionic hydrogel electrolyte: The poly-zwitterionic porous hydrogel is immersed in an ethylene glycol aqueous solution of soluble zinc salt. The mixture is allowed to stand until the volume of the poly-zwitterionic porous hydrogel no longer changes. During the standing process, the ethylene glycol aqueous solution of soluble zinc salt enters the poly-zwitterionic porous hydrogel, causing it to swell. The Zn in the ethylene glycol aqueous solution of soluble zinc salt... 2+ -COO coordinated adsorbed in zwitterionic porous hydrogels - or -SO3 -Site; simultaneously, ethylene glycol in the ethylene glycol aqueous solution of the soluble zinc salt forms a hydrogen bond network with the H2O of the zwitterionic porous hydrogel, leading to a decrease in the proportion of free water. The zwitterionic porous hydrogel then expands in volume to a stable state, yielding the zwitterionic hydrogel electrolyte. The H2O in the zwitterionic porous hydrogel refers to the hydrophilic groups (-SO3) on the zwitterionic porous hydrogel framework. - -COO - (-OH, -CONH-) bound water through hydrogen bonds or ion hydration.

[0008] Ethylene glycol is a low-volatility, highly polar organic solvent that can form a stable hydrogen bond network with water, stabilizing the distribution of zinc ions in solution. Furthermore, it can bind with the amphoteric groups (-SO3) within the zwitterionic porous hydrogel. - The -COO⁻ and -OH groups in ethylene glycol bind well; when ethylene glycol is blended with water, its viscosity maintains good wettability, avoiding interfacial instability caused by the high diffusion rate of soluble zinc salts in pure water systems; furthermore, the hydroxyl groups in the ethylene glycol molecule readily bind with Zn. 2+ Weak coordination or hydrogen bonding is formed, thereby stabilizing the distribution of zinc ions in the solution.

[0009] Preferably, the mass ratio of sodium methacrylate, sodium acrylate and N-hydroxymethylacrylamide is 1:1.2~1.5:2.0~2.5.

[0010] Preferably, the mass ratio of quaternary ammonium salt chitosan to sodium acrylate is 4:12~15.

[0011] Preferably, the mass ratio of N,N'-ethylenebisacrylamide to quaternary ammonium salt chitosan is 1:70~80.

[0012] Preferably, the conditions for free radical polymerization are: at room temperature, at a wavelength of 350 nm and an intensity of 100 mW / cm². 2 Stir for 2000s~2500s under ultraviolet light.

[0013] Preferably, in the ethylene glycol aqueous solution of the soluble zinc salt, the mass ratio of the ethylene glycol aqueous solution to the soluble zinc salt is 4.5~5:4.

[0014] Preferably, the soluble zinc salt is selected from Zn(CF3SO3)2, ZnSO4, ZnCl2 or Zn(CH3COO)2, more preferably Zn(CF3SO3)2. The core function of Zn(CF3SO3)2 is as a high-performance zinc salt electrolyte salt. Compared with traditional zinc salts, Zn(CF3SO3)2 has excellent ionic conductivity, electrochemical stability and interfacial compatibility, and can achieve a wider electrochemical window (>2.0V).

[0015] Preferably, in the ethylene glycol aqueous solution, the volume ratio of water to ethylene glycol is 1:0.5~1.

[0016] Preferably, the drying conditions are: freezing at -20℃ to -10℃ for 36h to 72h.

[0017] Preferably, the zwitterionic hydrogel is purified before drying. The purification process involves placing the zwitterionic hydrogel in a dialysis bag and dialyzing for 2 to 3 days, changing the dialysis solution every 12 hours. The dialysis bag has a molecular weight cutoff of 6 to 8 kDa, and the dialysis solution is deionized water.

[0018] Preferably, the photoinitiator is selected from α-ketoglutaric acid or 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone.

[0019] A second objective of this invention is to provide a zwitterionic hydrogel electrolyte prepared by the above-described method.

[0020] Preferably, the zwitterionic hydrogel electrolyte has ordered ion channels.

[0021] A third objective of this invention is to provide the application of zwitterionic hydrogel electrolytes in the preparation of aqueous zinc ion hybrid supercapacitors.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a method for preparing a zwitterionic hydrogel electrolyte. Sodium methacrylate, sodium acrylate, and N-hydroxymethylacrylamide are dissolved together in water to obtain a monomer solution. Using quaternary ammonium chitosan as a cationic modifier and N,N'-ethylenebisacrylamide as a crosslinking agent, the monomer solution, cationic modifier, and crosslinking agent are subjected to free radical polymerization under the action of a photoinitiator to form a zwitterionic hydrogel. After drying, a zwitterionic porous hydrogel is obtained. The zwitterionic porous hydrogel is immersed in an ethylene glycol aqueous solution of soluble zinc salt and allowed to stand until the volume of the zwitterionic porous hydrogel no longer changes. During the standing process, the ethylene glycol aqueous solution of soluble zinc salt enters the zwitterionic porous hydrogel, causing it to swell. The Zn in the ethylene glycol aqueous solution of soluble zinc salt... 2+ -COO coordinated adsorbed in zwitterionic porous hydrogels - or -SO3 -Simultaneously, ethylene glycol in the ethylene glycol aqueous solution of the soluble zinc salt forms a hydrogen bond network with H2O in the polyzwitterionic porous hydrogel, leading to a decrease in the proportion of free water. The polyzwitterionic porous hydrogel then expands in volume to a stable state, yielding the polyzwitterionic hydrogel electrolyte. The polyzwitterionic hydrogel electrolyte of this invention possesses ordered ion channels, which not only effectively inhibits the growth of zinc ion dendrites and reduces irreversible loss of zinc ions in the polyzwitterionic hydrogel electrolyte, but also significantly improves the coulombic efficiency and cycle life of the zinc ion mixed supercapacitor.

[0023] In particular, the sulfonic acid groups in sodium methacrylate form Zn donors along the molecular chains of the zwitterionic hydrogel. 2+ The "chain-like channel" of conduction enhances Zn 2+ Conductivity; The introduction of quaternary ammonium salt chitosan enhances the stability of the polyzomboplastin hydrogel electrolyte network structure. Through physical entanglement and cross-linking, it improves its mechanical stability and self-healing ability, avoiding structural disintegration and electrolyte stratification during repeated charge and discharge, thereby significantly extending device life and maintaining capacity stability; Ethylene glycol aqueous solution reduces free water activity and inhibits side reactions. At the same time, by regulating the physicochemical properties of soluble zinc salt in ethylene glycol aqueous solution, zinc ion transport efficiency is further improved.

[0024] 2. The polar functional groups (referring to all functional groups on the polymer network capable of forming hydrogen bonds or ion-dipole interactions with water molecules, such as sulfonate, carboxylate, amide, hydroxyl, and quaternary ammonium cations) in the zwitterionic hydrogel electrolyte of this invention form hydrogen bonds with water molecules, which can inhibit the activity of water molecules and water evaporation, establish a water-poor interface, and reduce the formation of zinc dendrites and side reactions. Simultaneously, the negatively charged polar groups introduced into the zwitterionic hydrogel, namely sulfonate and carboxylate groups, preferentially react with Zn. 2+ The interaction alters the shell structure of the ethylene glycol aqueous solution and redistributes ion flux, limiting Zn. 2+ Two-dimensional diffusion in the horizontal direction creates a uniform electric field, suppressing further exacerbation of the "point effect." Furthermore, this invention introduces anionic and cationic groups to form a zwitterionic network structure, constructing ordered ion migration channels within the zwitterionic hydrogel electrolyte, significantly improving Zn... 2+ The migration efficiency.

[0025] 3. Compared with traditional hydrogel electrolytes, the zwitterionic hydrogel electrolyte of the present invention has both excellent antifreeze properties and flexibility, which is attributed to its unique structural combination: First, it has a three-dimensional cross-linked and elastically reversible polymer backbone structure; second, its high water content and abundant polar functional groups enable water molecules to act as plasticizers; third, by introducing quaternary ammonium salt chitosan, it adds flexible natural polysaccharide segments.

[0026] Based on this, the zwitterionic hydrogel electrolyte of the present invention can adapt to extreme temperature environments, providing a high-performance electrolyte solution for power storage systems and flexible electronic devices, and has broad application prospects. Specifically, the sulfonic acid anions contained in sodium methacrylate sulfonate and the quaternary ammonium cations contained in quaternary ammonium chitosan both have strong hydration effects, effectively lowering the freezing point, inhibiting ice nucleation and growth, and altering the morphology of ice crystals, thereby endowing the zwitterionic hydrogel electrolyte with excellent antifreeze properties.

[0027] 4. The preparation method of the present invention has the advantages of simple process, low cost and high yield, and is suitable for large-scale production.

[0028] 5. When the zwitterionic hydrogel electrolyte of this invention is applied to an aqueous zinc-ion hybrid supercapacitor, its zinc ion migration channels effectively improve ionic conductivity. Simultaneously, the introduced organic mixed solvent significantly reduces free water activity, thereby inhibiting zinc dendrite formation, reducing irreversible zinc ion loss in the electrolyte, and significantly improving the coulombic efficiency and cycle life of the aqueous zinc-ion hybrid supercapacitor. This significant improvement in ionic conductivity enables the energy storage device to maintain high power density and long cycle life even under high-rate discharge conditions. Attached Figure Description

[0029] Figure 1 This is a diagram of the zwitterionic hydrogel electrolyte prepared in Example 1.

[0030] Figure 2 The polyzwitterionic porous hydrogel prepared in Example 1.

[0031] Figure 3 P((SMAS-AANa-NMA) / QCS)-Zn from Example 1 2+ The structural diagram.

[0032] Figure 4 The image shows the 1H NMR spectrum of N-hydroxymethylacrylamide.

[0033] Figure 5 This is the HNMR chromatogram of sodium acrylate.

[0034] Figure 6 The image shows the HNMR analysis of sodium methylpropenesulfonate.

[0035] Figure 7 The images shown are scanning electron microscope (SEM) images of the zwitterionic hydrogel electrolyte from Example 1, where a is magnified to 500 µm and b is magnified to 50 µm.

[0036] Figure 8 The graph shows the electrochemical stability test results of the zwitterionic hydrogel electrolyte in Example 1.

[0037] Figure 9 This is a schematic diagram of a zinc-ion button battery assembled using the zwitterionic hydrogel electrolyte of Example 1. Figure 9 The parallel sample is a zinc-ion button cell with eight zwitterionic hydrogel electrolytes assembled in the middle. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that the technical terms used in this invention are only for describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased commercially or prepared by existing methods. Among them, sodium methacrylate is denoted as SMAS; sodium acrylate is denoted as AANa; N-hydroxymethylacrylamide is denoted as NMA; quaternary ammonium salt chitosan is denoted as QCS; N,N'-ethylenebisacrylamide is denoted as EBA; the NMR data of the functional raw material monomers sodium acrylate, sodium methacrylate, sodium methacrylate, and N-hydroxymethylacrylamide of this invention are as follows: Figure 4 , Figure 5 as well as Figure 6 .

[0040] To address the problems of restricted ion migration, dendrite growth, and capacity decay inherent in traditional hydrogel electrolytes, this invention provides a method for preparing a polyzwitterionic hydrogel electrolyte, comprising the following steps: dissolving sodium methacrylate sulfonate, sodium acrylate, and N-hydroxymethylacrylamide together in water to obtain a monomer solution; using quaternary ammonium chitosan as a cationic modifier and N,N'-ethylenebisacrylamide as a crosslinking agent, under the action of a photoinitiator, subjecting the monomer solution, cationic modifier, and crosslinking agent to free radical polymerization to form a polyzwitterionic hydrogel, followed by drying to obtain a polyzwitterionic porous hydrogel; immersing the polyzwitterionic porous hydrogel in an ethylene glycol aqueous solution of soluble zinc salt, allowing it to stand until the volume of the polyzwitterionic porous hydrogel no longer changes; during the standing process, the ethylene glycol aqueous solution of soluble zinc salt enters the polyzwitterionic porous hydrogel, causing the polyzwitterionic porous hydrogel to swell, and the Zn in the ethylene glycol aqueous solution of soluble zinc salt... 2+ -COO coordinated adsorbed in zwitterionic porous hydrogels - or -SO3 -Site; at the same time, ethylene glycol in the ethylene glycol aqueous solution of soluble zinc salt forms a hydrogen bond network with H2O of the polyzwitterionic porous hydrogel, resulting in a decrease in the proportion of free water, and the volume of the polyzwitterionic porous hydrogel expands to a stable state, thus obtaining the polyzwitterionic hydrogel electrolyte.

[0041] Addressing the key issues of limited ion migration, dendrite growth, and capacity decay in traditional hydrogel electrolytes, this invention utilizes a "chain channel" constructed from sodium methacrylate to enhance Zn content. 2+ Conductivity was improved by enhancing the network structure stability through quaternary ammonium salt chitosan and by introducing ethylene glycol to regulate the physicochemical properties of soluble zinc salt in ethylene glycol aqueous solution to reduce free water activity, thereby achieving Zn 2+ The efficient directional migration and uniform deposition effectively suppress dendrite growth and side reactions, overcoming the technical defects of existing aqueous zinc ion mixed supercapacitor electrolytes, such as limited ion migration, short cycle life, and poor safety.

[0042] Specifically, by adjusting the ratio of monomer solution to cationic modifier, crosslinking agent content, and drying process parameters (such as freezing temperature and heating rate), gel networks with different pore structures, crosslinking densities, and water contents can be obtained under low temperature, high temperature, and different mechanical strain environments, achieving flexible control of their structure and properties. By precisely controlling reaction conditions, including: ① the molar or mass ratio of monomer solution to cationic modifier; ② the concentration of N,N'-ethylenebisacrylamide; ③ the amount of photoinitiator and the intensity and duration of ultraviolet irradiation; ④ the free radical polymerization temperature and stirring rate; ⑤ the drying temperature and heating rate; and ⑥ the volume ratio of ethylene glycol to water, the concentration of soluble zinc salt, and the immersion temperature and time during the immersion stage, the physical and chemical properties of the zwitterionic porous hydrogel can be effectively adjusted, ensuring efficient energy storage and release in the aqueous zinc ion mixed supercapacitor.

[0043] The technical solution of the present invention will be further explained and illustrated below with examples, as follows: Example 1 A method for preparing a polyzwitterionic hydrogel electrolyte includes the following steps: S1. Preparation of monomer solutions for zwitterionic hydrogels: In 5 mL of deionized water, 0.4 g of SMAS, 0.5 g of AANa, and 0.8 g of NMA were added sequentially. The mixture was stirred at 120 rpm on a magnetic stirrer at room temperature until all monomers were completely dissolved, yielding a homogeneous and transparent monomer solution. The monomer solution had a mass fraction of 25.37%.

[0044] S2. Add 0.16 g of QCS and 2 mg of EBA to the monomer solution. Heat in a water bath to 60°C and stir with a magnetic stirrer at 100 rpm for 25 min until the solution is clear. Then add 2 mg of α-ketoglutaric acid and stir for 5 min. Transfer to a glass mold and heat at a wavelength of 350 nm and an intensity of 100 mW / cm. 2 Irradiation under ultraviolet light for 2000s yielded crude zwitterionic hydrogel.

[0045] S3. The crude zwitterionic hydrogel product was placed in a dialysis bag and dialyzed for 2 days, with the dialysis solution being changed every 12 hours. The dialysis solution was deionized water, and the molecular weight cutoff of the dialysis bag was 6 kDa. After dialysis, zwitterionic hydrogel was obtained. The zwitterionic hydrogel was then frozen at -20°C for 12 hours. Subsequently, the frozen zwitterionic hydrogel was placed in a freeze dryer and dried for 36 hours to obtain a zwitterionic porous hydrogel.

[0046] S4. Deionized water and ethylene glycol are thoroughly mixed at a volume ratio of 1:1 to obtain an organic solution of deionized water and ethylene glycol. Then, 8.36 g of Zn(CF3SO3)2 is added to 10 mL of the organic solution of deionized water and ethylene glycol. Under stirring conditions, Zn(CF3SO3)2 is completely dissolved to form a transparent aqueous solution of soluble zinc salt in ethylene glycol.

[0047] S5. Immerse the zwitterionic porous hydrogel in an aqueous solution of soluble zinc salt in ethylene glycol, and let it stand for 10 hours to obtain the zwitterionic hydrogel electrolyte, denoted as P((SMAS-AANa-NMA) / QCS)-Zn. 2+ , structural formula as Figure 3 As shown.

[0048] Example 2 A method for preparing a polyzwitterionic hydrogel electrolyte includes the following steps: S1. Preparation of monomer solutions for zwitterionic hydrogels: In 5 mL of deionized water, 0.4 g of SMAS, 0.56 g of AANa, and 0.8 g of NMA were added sequentially. The mixture was stirred at 120 rpm on a magnetic stirrer at room temperature until all monomers were completely dissolved, yielding a homogeneous and transparent monomer solution. The mass fraction of the monomer solution was 26.03%.

[0049] S2. Add 0.16 g of QCS and 2 mg of EBA to the above monomer solution. Heat in a water bath to 60°C and stir at 100 rpm for 25 min until the solution is clear. Then add 2 mg of α-ketoglutaric acid and stir for 5 min. Transfer to a glass mold and heat at a wavelength of 350 nm and an intensity of 100 mW / cm². 2 Irradiation under ultraviolet light for 2500s yielded crude zwitterionic hydrogel.

[0050] S3. The crude zwitterionic hydrogel product was placed in a dialysis bag and dialyzed for 2 days, with the dialysis solution being changed every 12 hours. The dialysis solution was deionized water, and the molecular weight cutoff of the dialysis bag was 8 KD. After dialysis, zwitterionic hydrogel was obtained. The zwitterionic hydrogel was then frozen at -20°C for 12 hours. Subsequently, the frozen zwitterionic hydrogel was placed in a freeze dryer and dried for 72 hours to obtain a zwitterionic porous hydrogel.

[0051] S4. Deionized water and ethylene glycol are thoroughly mixed at a volume ratio of 1:1 to obtain an organic solution of deionized water and ethylene glycol. Then, 8.36 g of Zn(CF3SO3)2 is added to 10 mL of the organic solution of deionized water and ethylene glycol. Under stirring conditions, Zn(CF3SO3)2 is completely dissolved to form a transparent aqueous solution of soluble zinc salt in ethylene glycol.

[0052] S5. Immerse the polyzwitterionic porous hydrogel in an aqueous solution of soluble zinc salt in ethylene glycol, and let it stand for 10 hours to obtain the polyzwitterionic hydrogel electrolyte.

[0053] Example 3 A method for preparing a polyzwitterionic hydrogel electrolyte includes the following steps: S1. Preparation of monomer solutions for zwitterionic hydrogels: In 5 mL of deionized water, 0.4 g of SMAS, 0.6 g of AANa, and 1 g of NMA were added sequentially. The mixture was stirred at 120 rpm on a magnetic stirrer at room temperature until all monomers were completely dissolved, yielding a homogeneous and transparent monomer solution. The mass fraction of the monomer solution was 28.57%.

[0054] S2. Add 0.16 g of QCS and 2 mg of EBA to the above monomer solution. Heat in a water bath to 60°C and stir at 100 rpm for 25 min until the solution is clear. Then add 2 mg of α-ketoglutaric acid and stir for 5 min. Transfer to a glass mold and heat at a wavelength of 350 nm and an intensity of 100 mW / cm². 2 Irradiation under ultraviolet light for 2000s yielded crude zwitterionic hydrogel.

[0055] S3. The crude zwitterionic hydrogel product was placed in a dialysis bag and dialyzed for 2 days, with the dialysis solution being changed every 12 hours. The dialysis solution was deionized water, and the molecular weight cutoff of the dialysis bag was 6 kDa. After dialysis, zwitterionic hydrogel was obtained. The zwitterionic hydrogel was then frozen at -20°C for 12 hours. Subsequently, the frozen zwitterionic hydrogel was placed in a freeze dryer and dried for 36 hours to obtain a zwitterionic porous hydrogel.

[0056] S4. Deionized water and ethylene glycol are thoroughly mixed at a volume ratio of 1:1 to obtain an organic solution of deionized water and ethylene glycol. Then, 8.36 g of Zn(CF3SO3)2 is added to 10 mL of the organic solution of deionized water and ethylene glycol. Under stirring conditions, Zn(CF3SO3)2 is completely dissolved to form a transparent aqueous solution of soluble zinc salt in ethylene glycol.

[0057] S5. Immerse the polyzwitterionic porous hydrogel in an aqueous solution of soluble zinc salt in ethylene glycol, and let it stand for 10 hours to obtain the polyzwitterionic hydrogel electrolyte.

[0058] Example 4 A method for preparing a polyzwitterionic hydrogel electrolyte includes the following steps: S1. Preparation of monomer solutions for zwitterionic hydrogels: In 5 mL of deionized water, 0.4 g of SMAS, 0.48 g of AANa, and 0.8 g of NMA were added sequentially. The mixture was stirred at 120 rpm on a magnetic stirrer at room temperature until all monomers were completely dissolved, yielding a homogeneous and transparent monomer solution. The monomer solution had a mass fraction of 25.14%.

[0059] S2. Add 0.16 g of QCS and 2 mg of EBA to the above monomer solution. Heat in a water bath to 60°C and stir at 100 rpm for 25 min until the solution is clear. Then add 2 mg of α-ketoglutaric acid and stir for 5 min. Transfer to a glass mold and heat at a wavelength of 350 nm and an intensity of 100 mW / cm². 2 Irradiation under ultraviolet light for 2300s yielded crude zwitterionic hydrogel.

[0060] S3. The crude zwitterionic hydrogel product was placed in a dialysis bag and dialyzed for 2 days, with the dialysate being changed every 12 hours. The dialysate was deionized water, and the molecular weight cutoff of the dialysis bag was 6 KD. After dialysis, zwitterionic hydrogel was obtained. The zwitterionic hydrogel was then frozen at -10°C for 12 hours. Subsequently, the frozen zwitterionic hydrogel was placed in a freeze dryer and dried for 72 hours to obtain a zwitterionic porous hydrogel.

[0061] S4. Deionized water and ethylene glycol are thoroughly mixed at a volume ratio of 1:0.5 to obtain an organic solution of deionized water and ethylene glycol. Then, 8.36 g of Zn(CF3SO3)2 is added to 10 mL of the organic solution of deionized water and ethylene glycol. Under stirring conditions, Zn(CF3SO3)2 is completely dissolved to form a transparent aqueous solution of soluble zinc salt in ethylene glycol.

[0062] S5. Immerse the polyzwitterionic porous hydrogel in an aqueous solution of soluble zinc salt in ethylene glycol, and let it stand for 10 hours to obtain the polyzwitterionic hydrogel electrolyte.

[0063] observe Figure 1 It was found that the zwitterionic hydrogel electrolyte, after being soaked in an aqueous solution of soluble zinc salt in ethylene glycol until swelling equilibrium was reached, was a milky white gel-like substance.

[0064] observe Figure 2 It was found that the crude product of the zwitterionic hydrogel electrolyte was a colorless and transparent gel.

[0065] observe Figure 7 It was found that the surface of the zwitterionic hydrogel electrolyte is smooth, and local magnification to 50 μm shows that the zwitterionic hydrogel electrolyte has a relatively dense network structure.

[0066] Examples 1 to 4 of this invention all yielded polyzwitterionic hydrogel electrolytes with parallel effects. The following study uses the polyzwitterionic hydrogel electrolyte prepared in Example 1 as an example: I. Battery Assembly: Button batteries were assembled using the zwitterionic hydrogel electrolyte prepared in Example 1 as the electrolyte: Taking the CR2032 button cell as an example, in a glove box filled with argon gas, the negative electrode shell, spring, gasket, and zinc negative electrode are placed in sequence. The zwitterionic hydrogel electrolyte is then coated onto the zinc negative electrode. Next, the activated carbon positive electrode is placed in the box, the positive electrode shell is covered, and the cell is pressed firmly to obtain the button cell. (See...) Figure 9 As shown.

[0067] Depend on Figure 8The results show that the zinc-ion button battery exhibits excellent electrochemical cycling stability and structural stability. After 15,000 charge-discharge cycles, the battery's charge-discharge specific capacity curve (green curve) remained stable at approximately 270 mAh / g, with minimal capacity decay. This result demonstrates the significant advantages of zinc-ion button batteries assembled based on zwitterionic hydrogel electrolytes. They possess a high specific capacity of 270 mAh / g, a coulombic efficiency approaching 100%, and a cycle life of up to 15,000 cycles. This fully reflects the excellent electrochemical stability and highly reversible interfacial reactions of this battery system.

[0068] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

Claims

1. A method for preparing a polyzwitterionic hydrogel electrolyte, characterized in that, Includes the following steps: Sodium methacrylate, sodium acrylate, and N-hydroxymethylacrylamide were dissolved together in water to obtain a monomer solution; Using quaternary ammonium salt chitosan as a cationic modifier and N,N'-ethylenebisacrylamide as a crosslinking agent, the monomer solution, cationic modifier and crosslinking agent were subjected to free radical polymerization under the action of photoinitiator to form a zwitterionic hydrogel. After drying, a zwitterionic porous hydrogel was obtained. A zwitterionic porous hydrogel was immersed in an ethylene glycol aqueous solution of soluble zinc salt and allowed to stand until the volume of the zwitterionic porous hydrogel no longer changed. During the standing process, the ethylene glycol aqueous solution of soluble zinc salt entered the zwitterionic porous hydrogel, causing it to swell. The Zn in the ethylene glycol aqueous solution of soluble zinc salt also increased. 2+ -COO coordinated adsorbed in zwitterionic porous hydrogels - or -SO3 - Site; simultaneously, ethylene glycol in the ethylene glycol aqueous solution of soluble zinc salt forms a hydrogen bond network with H2O of the polyzwitterionic porous hydrogel, resulting in a decrease in the proportion of free water, thus obtaining a polyzwitterionic hydrogel electrolyte.

2. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 1, characterized in that, The mass ratio of sodium methacrylate, sodium acrylate and N-hydroxymethylacrylamide is 1:1.2~1.5:2.0~2.

5.

3. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 1, characterized in that, The mass ratio of quaternary ammonium salt chitosan to sodium acrylate is 4:12~15.

4. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 1, characterized in that, The conditions for free radical polymerization are: irradiation at room temperature and under ultraviolet light for 2000s~2500s.

5. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 1, characterized in that, Soluble zinc salts are selected from Zn(CF3SO3)2, ZnSO4, ZnCl2 or Zn(CH3COO)2.

6. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 1, characterized in that, In the ethylene glycol aqueous solution of soluble zinc salt, the mass ratio of the ethylene glycol aqueous solution to the soluble zinc salt is 4.5~5:

4.

7. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 6, characterized in that, In an aqueous solution of ethylene glycol, the volume ratio of water to ethylene glycol is 1:0.5~1.

8. The method for preparing a polyzwitterionic hydrogel electrolyte according to claim 1, characterized in that, The drying conditions are: freezing at -20℃ to -10℃ for 36h to 72h.

9. A polyzwitterionic hydrogel electrolyte, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the zwitterionic hydrogel electrolyte of claim 9 in the preparation of an aqueous zinc ion hybrid supercapacitor.

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