A double-network hydrogel electrolyte with a wide temperature range, preparation method and application

Abstract

The present invention provides a double-network hydrogel electrolyte with a wide temperature range, a preparation method, and an application thereof. The preparation method comprises: using carrageenan, sulfobetaine methacrylate, and acrylamide as raw materials to prepare a carrageenan-poly(sulfobetaine methacrylate / acrylamide) double-network hydrogel having a double-network structure; then adjusting the concentration of the soaking solution by a solution replacement method to obtain a carrageenan-poly(sulfobetaine methacrylate / acrylamide) double-network hydrogel electrolyte with a wide temperature range. The double-network hydrogel electrolyte is then assembled with an MnO2@CNT electrode and a zinc sheet electrode to obtain a zinc ion battery. The prepared Zn-MnO2 battery can still maintain stable energy output under low temperature conditions of 30°C and high temperature conditions of 60°C, and has application prospects in flexible wearable devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of conductive hydrogel materials, and in particular relates to a double-network hydrogel electrolyte with a wide temperature range, a preparation method and an application thereof. Background Art

[0002] The rapid development of wearable and portable electronic products has driven the demand for flexible energy storage devices such as aqueous batteries. Among them, liquid electrolytes are widely used in energy storage devices. Electrolytes are ionic conductors that conduct electricity between the positive and negative electrodes of batteries. They play a vital role in the energy density, power density, cycle life, safety performance, etc. of batteries. However, due to some inevitable disadvantages, such as dendritic corrosion and electrolyte leakage, their application is limited. Therefore, hydrogel electrolytes with solid-like mechanical properties and liquid-like ion transfer rates have gradually become a research hotspot. As one of the key components of flexible energy storage devices, the quality of their properties is a key factor in determining the performance of energy storage devices. An ideal hydrogel electrolyte should have good electrical conductivity, excellent mechanical properties and a wide operating temperature range to adapt to actual application environments.

[0003] Ionic conductivity is an important performance indicator of electrolytes. Therefore, whether the electrolyte has excellent ion transport performance under different usage environments is an important factor affecting the electrochemical performance of the battery. For example, foreign literature (Minfeng Chen, Jizhang Chen, *Weijun Zhou, Xiang Han, Yagang Yao, *and Ching-Ping Wong, Realizing an All-Round Hydrogel Electrolyte toward Environmentally Adaptive Dendrite-Free Aqueous Zn–MnO2 Batteries, AM2021, 33, 2007559) points out that hydrogel electrolytes have a high water content and will freeze at low temperatures and evaporate at high temperatures, causing the conductivity to deteriorate and thus affecting the performance of the battery. This is a problem that needs to be solved urgently.

[0004] At the same time, flexible energy storage devices should have excellent mechanical properties and stability, and be able to maintain stable energy output even under the influence of the external environment. This is also a hot topic in research work. However, natural polymer hydrogels usually lack excellent mechanical properties and have unsatisfactory and unstable electrochemical properties. For example, the conductivity drops sharply under low and high temperature conditions. Currently, the design and preparation of hydrogel electrolytes with good mechanical properties, environmental stability and excellent electrochemical properties is a problem that needs to be solved in current research work. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a double-network hydrogel electrolyte with a wide temperature range, and its preparation method comprises the following steps:

[0006] (1) dissolving carrageenan in an aqueous solution, stirring at 80-100° C. for 60-90 minutes, then adding zwitterionic sulfobetaine methacrylate monomer, acrylamide monomer, 0.05-0.2% of the total molar amount of the two monomers as a crosslinker N,N-methylenebisacrylamide, 0.3-0.6% of the total molar amount of the two monomers as an initiator, and zinc chloride, mixing and stirring for 60 minutes, and then pouring into a mold, keeping the mixture at -40-0° C. for 1-2 hours, and then returning it to room temperature at 0-25° C. for 2-8 hours to obtain a gel-like mixture, and then polymerizing it under ultraviolet light to obtain a carrageenan-poly(sulfobetaine methacrylate / acrylamide) composite hydrogel;

[0007] (2) dissolving zinc chloride and lithium bromide in water to obtain a uniform mixed salt solution;

[0008] (3) Soaking the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 5 to 360 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte.

[0009] Specifically, the ratio of the mass of the carrageenan described in step (1) to the total mass of the zwitterionic sulfobetaine methacrylate monomer and the acrylamide monomer is 1:6 to 1:35.

[0010] Specifically, the molar ratio of the zwitterionic sulfobetaine methacrylate monomer to the acrylamide monomer in step (1) is 1:5 to 1:30.

[0011] Specifically, the initiator in step (1) is 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone or α-ketoglutaric acid.

[0012] Specifically, the molar concentration of zinc chloride in step (1) is 1 to 2 mol L -1 .

[0013] Specifically, the molar concentration of zinc chloride in the mixed salt solution in step (2) is 1 to 2 mol L -1 .

[0014] Specifically, the molar concentration of lithium bromide in the mixed salt solution in step (2) is 4 to 12 mol L -1 .

[0015] The present invention also provides a double-network hydrogel electrolyte with a wide temperature range for use in energy storage devices or supercapacitors.

[0016] Specifically, the present invention also provides an application of a double-network hydrogel electrolyte with a wide temperature range in the field of zinc-manganese dioxide batteries.

[0017] The advantages of the present invention are:

[0018] The present invention obtains a double-network hydrogel electrolyte with excellent performance in a wide temperature range (elongation at break of -40°C to 155% and tensile strength of 117KPa, elongation at break of 80°C to 185% and tensile strength of 119KPa) through the synergistic effect of raw materials, raw material reaction ratios and processes. Carrageenan is selected as the first network of the double-network hydrogel electrolyte, which has excellent toughness and energy dissipation mechanism. Zwitterionic monomers and acrylamide monomers are selected for copolymerization as the second network, so that in the entire process of energy dissipation of the hydrogel electrolyte, energy is preferentially dissipated effectively through the first network and the reversible hydrogen bonds between the two networks. At the same time, the second copolymer network can maintain the integrity of the hydrogel and ensure that ion transmission is not affected by the outside world. This provides a basis for the double-network hydrogel to have both excellent mechanical properties and conductive properties. By the method of solution replacement, a salt solution is introduced into the hydrogel obtained by the above process, thereby widening the temperature range of the electrolyte (the conductivity is 20.8mS cm at -20°C). -1 , the conductivity at 50℃ is 40.3mS cm -1 The introduction of salt solution not only destroys the intermolecular hydrogen bonds between free water molecules in the hydrogel polymer electrolyte and enhances the interaction between water molecules and the hydrogel network, but also forms a strong interaction with water molecules, significantly enhancing the water retention and antifreeze capabilities, thereby obtaining a double-network hydrogel electrolyte with a wide temperature range. Its performance is superior to some existing technologies. For example, the antifreeze zwitterionic double-network hydrogel electrolyte reported in the prior art has a conductivity of only 10.38 mS cm at -20°C. -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A comparison of the tensile properties of the double-network hydrogel electrolytes prepared in Examples 1, 6, 7, 8, and 9;

[0020] Figure 2 A comparison of the electrical conductivities of the double-network hydrogel electrolytes prepared in Examples 1, 2, and 3;

[0021] Figure 3 This is a comparison chart of the tensile properties of the double-network hydrogel electrolyte prepared in Example 1 at 80°C and -40°C;

[0022] Figure 4 The conductivity diagram of the double-network hydrogel electrolyte prepared in Example 1 at different temperatures;

[0023] Figure 5 This is a compression performance diagram of the double network hydrogel electrolyte prepared in Example 1;

[0024] Figure 6 This is a cyclic voltammetry curve of the Zn-MnO2 battery prepared in Example 11;

[0025] Figure 7 This is the charge and discharge curve of the Zn-MnO2 battery prepared in Example 11. DETAILED DESCRIPTION

[0026] The method of the present invention is described below through specific examples. The examples are only specific descriptions of the claims of the present invention, and the claims include but are not limited to the contents of the examples. Unless otherwise specified, the reagents and materials described in the following examples can be obtained from commercial channels; the test methods are conventional methods unless otherwise specified. The electrochemical workstation used in the examples is the CHI604E model of Shanghai Chenhua, the battery testing system is the CT2001A model of Wuhan Blue Electric Electronics Co., Ltd., and the universal material testing machine is the SHIMADZUAG-I model of Shimadzu Corporation of Japan.

[0027] Example 1: The preparation steps of hydrogel electrolyte 1 are as follows:

[0028] The specific steps are as follows:

[0029] Step 1: 0.5 g carrageenan was dissolved in 14 mL aqueous solution, stirred at 95 ° C for 60 min, and then the zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, 0.1% of the total molar amount of the two monomers as a crosslinker N, N-methylenebisacrylamide crosslinker, 0.5% of the total molar amount of the two monomers as an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at -20°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0030] Step 2: Dissolve zinc chloride and lithium bromide in water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 6 mol L -1 .

[0031] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 360 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 1 with a wide temperature range.

[0032] Example 2: The preparation steps of hydrogel electrolyte 2 are as follows:

[0033] Step 1: 0.5 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 80 ° C for 60 min. Then, a zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer ratio of 1:10, a crosslinker N, N-methylenebisacrylamide crosslinker with a total molar amount of 0.1% of the two monomers, an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone with a total molar amount of 0.5% of the two monomers, and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at -30°C for 1 hour, it was restored to room temperature at 10°C for 4 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0034] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 5 mol L -1 .

[0035] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 240 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 2 having high ionic conductivity, mechanical properties and a wide operating temperature range.

[0036] Example 3: The preparation steps of hydrogel electrolyte 3 are as follows:

[0037] Step 1: 0.5 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 90 ° C for 90 min. Then, a zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:30, a crosslinker N, N-methylenebisacrylamide crosslinker with a total molar ratio of 0.05% of the two monomers, an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone with a total molar ratio of 0.5% of the two monomers, and 1 mol L -1Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at 0°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0038] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 4 mol L -1 .

[0039] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 300 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 3 with a wide temperature range.

[0040] Example 4: The preparation steps of hydrogel electrolyte 4 are as follows:

[0041] Step 1: Dissolve 0.5g carrageenan in 14mL aqueous solution, stir at 90℃ for 60min, then add zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, crosslinker N,N-methylenebisacrylamide crosslinker with a total molar ratio of 0.08% of the two monomers, initiator α-ketoglutaric acid with a total molar ratio of 0.3% of the two monomers, and 1mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at -20°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0042] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 8 mol L -1 .

[0043] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 360 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 4 with a wide temperature range.

[0044] Example 5: The preparation steps of hydrogel electrolyte 5 are as follows:

[0045] Step 1: Dissolve 0.5 g carrageenan in 14 mL aqueous solution, stir at 90 ° C for 60 min, then add zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, 0.05% of the total molar amount of the two monomers as crosslinker N, N-methylenebisacrylamide crosslinker, 0.3% of the total molar amount of the two monomers as initiator α-ketoglutaric acid and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at 0°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0046] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 12 mol L -1 .

[0047] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 120 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 5 having high ionic conductivity, mechanical properties and a wide operating temperature range.

[0048] Example 6: The preparation steps of hydrogel electrolyte 6 are as follows:

[0049] Step 1: 0.17 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 80 ° C for 60 min. Then, zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, 0.1% of the total molar amount of the two monomers as crosslinker N, N-methylenebisacrylamide crosslinker, 0.5% of the total molar amount of the two monomers as initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at 0°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0050] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 4 mol L -1 .

[0051] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 240 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 6 with a wide temperature range.

[0052] Example 7: The preparation steps of hydrogel electrolyte 7 are as follows:

[0053] Step 1: 0.34 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 90 ° C for 60 min. Then, a zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, a crosslinker N, N-methylenebisacrylamide crosslinker with a total molar ratio of 0.1% of the two monomers, an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone with a total molar ratio of 0.5% of the two monomers, and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at 0°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0054] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 4 mol L -1 .

[0055] Step 3: Soak the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 360 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 7 with high ionic conductivity, mechanical properties and a wide operating temperature range.

[0056] Example 8: The preparation steps of hydrogel electrolyte 8 are as follows:

[0057] Step 1: 0.67 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 95 ° C for 60 min. Then, zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, a crosslinker N, N-methylenebisacrylamide crosslinker with a total molar ratio of 0.08% of the two monomers, an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone with a total molar ratio of 0.5% of the two monomers, and 1 mol L -1Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at -10°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0058] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 6 mol L -1 .

[0059] Step 3: Soak the carrageenan-poly(sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 240 minutes to obtain a carrageenan-poly(sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 8 with a wide temperature range.

[0060] Example 9: The preparation steps of hydrogel electrolyte 9 are as follows:

[0061] Step 1: 0.84 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 100 ° C for 90 min. Then, a zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, a crosslinker N, N-methylenebisacrylamide crosslinker with a total molar ratio of 0.05% of the two monomers, an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone with a total molar ratio of 0.5% of the two monomers, and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at -20°C for 1 hour, it was restored to room temperature at 25°C for 2 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0062] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 4 mol L -1 .

[0063] Step 3: Soak the carrageenan-poly(sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 360 minutes to obtain a carrageenan-poly(sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 9 with a wide temperature range.

[0064] Example 10: The preparation steps of the hydrogel electrolyte 10 are as follows:

[0065] Step 1: 0.5 g carrageenan was dissolved in 14 mL aqueous solution and stirred at 95 ° C for 60 min. Then, zwitterionic sulfobetaine methacrylate monomer and acrylamide monomer with a monomer molar ratio of 1:20, a crosslinker N, N-methylenebisacrylamide crosslinker with a total molar ratio of 0.12% of the two monomers, an initiator 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone with a total molar ratio of 0.5% of the two monomers, and 1 mol L -1 Zinc chloride was added, mixed and stirred evenly, and then poured into a mold. After cooling at 0°C for 1 hour, it was restored to room temperature at 25°C for 6 hours, and then polymerized under ultraviolet light for 3 hours to obtain carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel.

[0066] Step 2: Dissolve zinc chloride and lithium bromide in deionized water to obtain a uniform mixed salt solution, where the concentration of zinc chloride is 1 mol L -1 , lithium bromide concentration is 4 mol L -1 .

[0067] Step 3: Soak the carrageenan-poly(sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 360 minutes to obtain a carrageenan-poly(sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 10 with a wide temperature range.

[0068] Example 11: Preparation of a zinc-manganese dioxide battery based on carrageenan-poly(sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte 1, specifically comprising the following steps:

[0069] (1) Before electrochemical deposition, the carbon nanotube paper was immersed in a solution consisting of ethanol and deionized water and ultrasonicated for 3 minutes to obtain a looser structure. Subsequently, the above-mentioned CNT paper, platinum sheet and Ag / AgCl electrode were used as working electrode, counter electrode and reference electrode, respectively. Electrodeposition was then carried out in a 0.1M Mn(CH3COO)2 solution at 1.0V for 900 seconds. After the completion of the electrochemical deposition, the prepared MnO2@CNT electrode was washed with deionized water and dried. The loading amount of the MnO2 was 1.2mg cm -2 ;

[0070] (2) The MnO2@CNT electrode prepared in step (1), the smooth zinc sheet, and the double-network hydrogel electrolyte 1 prepared in Example 1 (i.e., the electrolyte obtained in Example 1) were used as the positive electrode material, the negative electrode material, and the electrolyte, respectively, and assembled into a Zn-MnO2 button cell by a simple "sandwich" lamination method. Here, all the button cells used in the experiment were assembled by conventional methods using a circular zinc sheet with a diameter of 1 cm, a circular MnO2@CNT electrode with a diameter of 1 cm, and the corresponding hydrogel electrolyte. The button cell shell model was CR2032.

[0071] (3) The Zn-MnO2 button cell assembled in step (2) was tested for its cyclic voltammetry performance using an electrochemical workstation (scan rate of 100 mV s -1 , voltage window is 0.8~1.9V), and its constant current charge and discharge performance is tested using the Blue Electric Battery Test System.

[0072] The battery's cyclic voltammetry and charge-discharge test curves are as follows: Figure 6 、 7 As shown, the battery capacity of Example 11 is 0.25A g -1 290mA hg at current density -1 , which is superior to existing technologies, such as AMP-Mn / PVA hydrogel electrolyte batteries (0.2A g -1 267mA hg at current density -1 , Existing technology: Y.Hu, P.Shen, NaZeng, L.Wang, DiYan, L.Cui, K.Yang, C.Zhai, Hybrid Hydrogel Electrolyte Based on Metal-OrganicSupermolecular Self-Assembly and Polymer Chemical Cross-Linking for Rechargeable Aqueous Zn-MnO2 Batteries, ACS Appl.Mater.Interfaces 12(37)(2020)42285–42293).

[0073] The prepared Zn-MnO2 battery can still maintain stable energy output under low temperature of -30℃ and high temperature of 60℃.

[0074] Comparative Example 1: Antifreezing Zwitterionic-Based Hydrogel Electrolyte for Aqueous Zn Ion Batteries, Chunmei Yuan, Xin Zhong, Peishu Tian, Zhe Wang, Guanghui Gao, Lianfeng Duan, Chunsheng Wang*, and Fengwei Shi*, ACS Appl. Energy Mater. 2022, 5, 7530-7537.

[0075] First, 1.25g of sodium alginate was added to 40mL of water and heated at 60°C for 1h. Then, 1.25g of acrylamide and 10g of zwitterionic sulfobetaine methacrylate monomers were added to the above solution in sequence, stirred evenly, and 0.03mol% of the total molar amount of the two monomers as a crosslinker N,N-methylenebisacrylamide crosslinker and 0.15mol% of the total molar amount of the two monomers as an initiator potassium persulfate were added. The resulting mixture was then poured into a mold and allowed to stand at 60°C for 6h until the hydrogel film was fully formed. The hydrogel was then immersed in a mixed solution of 5mol / L ZnCl2 and 4mol / L LiCl for 12h to obtain a double network hydrogel electrolyte.

[0076] The properties of the double network hydrogel electrolytes of Examples 1 to 10 and Comparative Example 1 are shown in Table 1 below.

[0077] Table 1 Various properties of double network hydrogel electrolytes of Examples 1 to 10 and Comparative Example 1

[0078]

[0079] In summary:

[0080] It can be seen from Table 1 that: compared with Comparative Example 1 and the prior art, the mechanical and electrochemical properties of the electrolyte obtained in the present invention are the most excellent; in all embodiments, the raw materials, raw material ratios and process parameters of each embodiment are different, among which the performance of the gel electrolyte obtained in Example 1 is the most excellent, which shows that the present invention is to obtain the most excellent performance of the material through the synergistic effect of raw materials, raw material ratios and processes. In addition, the double network hydrogel electrolyte 1 obtained by the present invention has a tensile strength of 117KPa at -40°C, a tensile strength of 165KPa at -20°C, and a tensile strength of 119KPa at 80°C. The mechanical properties of the electrolyte obtained in Example 1 are better than those of Comparative Example 1 (131.2KPa at room temperature, 133.4KPa at -20°C, and no high temperature performance is disclosed) at room temperature (280KPa), low temperature (tensile strength of 165KPa at -20°C), and high temperature (tensile strength of 119KPa at 80°C). Figure 5 The area enclosed by the two curves in the compression curve represents the energy loss during the compression-decompression process. By comparing the enclosed area with the area enclosed by the compression curve, it can be seen that the energy loss coefficient is very small. At the same time, when the pressure is 0 during the decompression process, the deformation of the horizontal axis is close to 0, which means that there is almost no irreversible plastic deformation after the gel undergoes the compression-decompression process, which shows that the material obtained by the present invention has good recovery. In summary: the present invention introduces multiple hydrogen bond interactions and reversible electrostatic interactions into the double-network hydrogel electrolyte through hydrogel structure design, monomers, monomer reaction ratios and process synergy, giving the hydrogel electrolyte relatively excellent mechanical properties and ionic conductivity, and under the synergistic effect, greatly improving the comprehensive performance of the current hydrogel as an electrolyte. The hydrogel electrolyte obtained by the present invention has excellent ionic conductivity and excellent mechanical properties under high and low temperature conditions in a wide temperature range, and has good application in Zn-MnO2 batteries. The flexible energy storage device of the hydrogel electrolyte of the present invention can have excellent use prospects in wearable electronic devices.

Claims

1. A double-network hydrogel electrolyte with a wide temperature range, characterized by: Its preparation method comprises the following steps: (1) dissolving carrageenan in an aqueous solution, stirring at 80-100° C. for 60-90 minutes, then adding zwitterionic sulfobetaine methacrylate monomer, acrylamide monomer, 0.05-0.2% of the total molar amount of the two monomers as a crosslinker N,N-methylenebisacrylamide, 0.3-0.6% of the total molar amount of the two monomers as an initiator, and zinc chloride, mixing and stirring for 60 minutes, and then pouring into a mold, keeping the mixture at -40-0° C. for 1-2 hours, and then returning it to room temperature at 0-25° C. for 2-8 hours to obtain a gel-like mixture, and then polymerizing it under ultraviolet light to obtain a carrageenan-poly(sulfobetaine methacrylate / acrylamide) composite hydrogel; (2) dissolving zinc chloride and lithium bromide in water to obtain a uniform mixed salt solution; (3) Soaking the carrageenan-poly (sulfobetaine methacrylate / acrylamide) composite hydrogel obtained in step (1) in the mixed salt solution obtained in step (2) for 5 to 360 minutes to obtain a carrageenan-poly (sulfobetaine methacrylate / acrylamide) double network hydrogel electrolyte.

2. The double-network hydrogel electrolyte with a wide temperature range according to claim 1, characterized in that: The ratio of the mass of the carrageenan described in step (1) to the total mass of the zwitterionic sulfobetaine methacrylate monomer and the acrylamide monomer is 1:6 to 1:

35.

3. The double-network hydrogel electrolyte with a wide temperature range according to claim 1, characterized in that: The molar ratio of the zwitterionic sulfobetaine methacrylate monomer to the acrylamide monomer in step (1) is 1:5 to 1:

30.

4. The double-network hydrogel electrolyte with a wide temperature range according to claim 1, characterized in that: The initiator in step (1) is 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone or α-ketoglutaric acid.

5. The double-network hydrogel electrolyte with a wide temperature range according to claim 1, characterized in that: The molar concentration of zinc chloride in step (1) is 1 to 2 mol L -1 .

6. The double-network hydrogel electrolyte with a wide temperature range according to claim 1, characterized in that: The molar concentration of zinc chloride in the mixed salt solution of step (2) is 1-2 mol L -1 .

7. The double-network hydrogel electrolyte with a wide temperature range according to claim 1, characterized in that: The molar concentration of lithium bromide in the mixed salt solution of step (2) is 4 to 12 mol L -1 .

8. Use of the double-network hydrogel electrolyte with a wide temperature range according to any one of claims 1 to 7 in the field of energy storage devices or supercapacitors.

9. Application of the double-network hydrogel electrolyte with a wide temperature range according to any one of claims 1 to 7 in the field of zinc-manganese dioxide batteries.

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