Zwitterionic-based gel electrolyte and method of making same

Abstract

This invention discloses an amphoteric gel electrolyte and its preparation method. The method involves dissolving acrylic acid and sulfobetaine in an aqueous solution of polyvinyl alcohol and stirring to obtain a monomer mixture. N-N-methylenebisacrylamide is added to the monomer mixture, and after stirring until homogeneous, an initiator is added, and the reaction is continued with stirring. The product is then thermally polymerized to obtain an amphoteric gel. The amphoteric gel is then immersed in a zinc sulfate solution for treatment, followed by swelling treatment in a potassium hydroxide solution to obtain the amphoteric gel electrolyte. In this gel electrolyte, the quaternary ammonium groups of sulfobetaine and the carboxylic acid groups of acrylic acid form highly efficient ion migration channels, thereby improving conductivity. The high sensitivity of polyvinyl alcohol to the Hofmeister effect of sulfate groups enhances the mechanical strength of the gel.

Description

Technical Field

[0001] This invention belongs to the field of polymer and energy storage technology, and relates to an amphoteric ion-based gel electrolyte and its preparation method. Background Technology

[0002] With rapid societal development and continuous infrastructure construction, the demand for fossil fuels such as coal, oil, and natural gas is constantly increasing. Consequently, the overexploitation and deep dependence on fossil fuels are placing immense pollution pressure on nature and the ecological environment, making the development of next-generation green chemical clean energy particularly important. Flexible batteries have attracted widespread attention due to their superior performance in chemical energy storage and conversion. Their controllable size and excellent flexibility make them an indispensable part of portable wearable devices. Currently, portable electronic devices primarily rely on non-flexible lithium-ion batteries for power. However, these batteries cannot meet the demands of digital textiles for energy storage devices that require safety, comfort, small size, high capacity, and environmental friendliness. Zinc-air batteries possess numerous advantages, including high theoretical energy density, good safety, low cost, environmental friendliness, and rechargeability, making them an ideal choice for designing wearable flexible power sources. A key issue in flexible zinc-air batteries is the need to use solid-state electrolytes instead of traditional liquid electrolytes. Therefore, the development of advanced solid-state electrolyte systems is crucial to meeting the requirements of the battery's charging and discharging process, which plays a vital role in the performance of zinc-air batteries.

[0003] Gel polymer electrolytes need to have high ionic conductivity, excellent flexibility, and good interfacial compatibility with the electrodes. The use of such electrolytes makes it possible to develop high-performance flexible solid-state zinc-air batteries. However, the existing gel polymer electrolytes have poor conductivity and mechanical strength, which seriously limits the widespread use of zinc-air batteries. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides an amphoteric ion-based gel electrolyte and its preparation method, thereby solving the technical problems of poor conductivity and mechanical strength of gel polymer electrolytes in the prior art.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0007] S1: Dissolve acrylic acid and sulfobetaine in an aqueous solution of a polymer and stir to obtain a monomer mixture; the polymer is at least one of polyvinyl alcohol, polyacrylamide, and sodium polyacrylate.

[0008] S2: Add NN methylenebisacrylamide to the monomer mixture, stir evenly, add initiator, continue stirring to react, and then thermally polymerize the product to obtain zwitterionic gel;

[0009] S3: After soaking the zwitterionic gel in an ionic solution, the product is swollen in a potassium hydroxide solution to obtain the zwitterionic gel electrolyte; the ionic solution is at least one of zinc sulfate solution, sodium sulfate and sodium citrate.

[0010] Preferably, the ratio of acrylic acid, sulfobetaine and polymer is (1~3)mL:(0.1~2)g:(0.1~1)g.

[0011] Preferably, the preparation process of the aqueous solution of the polymer is as follows: 0.1~1 g of polymer is added to 10~50 mL of water, and then stirred at 50~100 °C to dissolve it, thereby obtaining the aqueous solution of the polymer.

[0012] Preferably, the ratio of acrylic acid, sulfobetaine, NN methylenebisacrylamide and initiator is (1~3) mL:(0.1~2) g:(0.01~0.05) g:(0.01~0.1) g.

[0013] Preferably, NN methylenebisacrylamide is added to the monomer mixture, stirred for 1-2 h, then an initiator is added, and stirring is continued for 10-60 min.

[0014] Preferably, the temperature during the thermal polymerization process is 40~60 ℃ and the time is 3~6 h.

[0015] Preferably, the concentration of the ionic solution is 0.1~3 M, and the zwitterionic gel is immersed in the ionic solution for 1~2 days.

[0016] Preferably, the concentration of the potassium hydroxide solution is 3-6 M, and the swelling treatment time is 1-2 days.

[0017] An amphoteric ion-based gel electrolyte is prepared by the above method; the ionic conductivity of the amphoteric ion-based gel electrolyte is 250~310 mS / cm; the tensile strength is 20~50 kPa.

[0018] A zinc-air battery comprising the aforementioned zwitterionic gel electrolyte; the open-circuit voltage of the zinc-air battery is 1.40~1.43V.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This invention provides a method for preparing a zwitterionic gel electrolyte. The method uses sulfobetaine, acrylic acid, and a polymer as raw materials. Based on the action of an initiator, a free radical in-situ polymerization reaction is initiated between sulfobetaine and acrylic acid monomers to form a sulfobetaine / acrylic acid network as the first backbone. The polymer forms a rigid second backbone. The gel is then immersed in an ionic solution containing both cations and anions. The cations can crosslink with the gel, improving its mechanical strength, while the anions cause PVA chains to precipitate through the Hofmeister effect, further enhancing the gel's mechanical strength. Thus, the Hofmeister effect enhances both the gel's conductivity and mechanical strength, ultimately forming a dual-network gel electrolyte. In this dual-network gel electrolyte, the quaternary ammonium groups of sulfobetaine and the carboxylic acid groups of acrylic acid form highly efficient ion migration channels, thereby improving conductivity. The high sensitivity of polyvinyl alcohol to the Hofmeister effect of sulfate groups enhances the gel's mechanical strength. The resulting gel electrolyte has a honeycomb porous structure, capable of adsorbing a large amount of electrolyte solution and exhibiting excellent hydration.

[0021] Furthermore, the ratio of acrylic acid, sulfobetaine, and polymer is (1~3) mL:(0.1~2) g:(0.1~1) g, which enables the prepared hydrogel to have excellent electrical conductivity and mechanical strength.

[0022] Furthermore, the preparation process of the aqueous solution of the polymer is as follows: 0.1~1 g of polyvinyl alcohol is added to 10~50 mL of water, and then stirred at 50~100 °C to dissolve it, thereby obtaining the aqueous solution of polyvinyl alcohol, which can make the gel form a double network structure, with one network being betaine acrylic acid and the other network being polyvinyl alcohol.

[0023] Furthermore, the ratio of acrylic acid, sulfobetaine, NN methylenebisacrylamide and initiator is (1~3) mL:(0.1~2) g:(0.01~0.05) g:(0.01~0.1) g, which can make the degree of gel crosslinking appropriate and the mechanical strength optimal.

[0024] Furthermore, adding NN methylenebisacrylamide to the monomer mixture and stirring for 1-2 hours, followed by adding an initiator and continuing stirring for 10-60 minutes, allows the persulfate ions in the initiator to effectively induce the polymer to begin crosslinking.

[0025] Furthermore, during the thermal polymerization process, the temperature is 40~60 ℃ and the time is 3~6 h, which can effectively catalyze the polymerization of polymer chains.

[0026] Furthermore, the concentration of the ionic solution is 0.1~3 M. Soaking the zwitterionic gel in the ionic solution for 1~2 days allows zinc ions in the ionic solution to crosslink with the gel, and sulfate ions to toughen the PVA chains through the Hofmeister effect.

[0027] Furthermore, the concentration of the potassium hydroxide solution is 3-6 M, and the swelling treatment time is 1-2 days, which allows the gel to swell and fully absorb the potassium hydroxide electrolyte, making it suitable for zinc-air batteries. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The following are bar charts showing the conductivity of zwitterionic gel electrolytes prepared in Examples 1-3 of this invention.

[0030] Figure 2 The stress-strain curves of the zwitterionic gel electrolytes prepared in Examples 1-3 of this invention are shown.

[0031] Figure 3 This is a scanning electron microscope image of the zwitterionic gel electrolyte prepared in Example 2 of the present invention;

[0032] Figure 4 The diagram shows the open-circuit voltage of a flexible zinc-air battery assembled using the zwitterionic gel electrolyte prepared in Example 2 of this invention. Detailed Implementation

[0033] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0035] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0036] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0037] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0038] This invention provides a method for preparing zwitterionic gel electrolytes, comprising the following steps:

[0039] S1: Add 0.1~1 g of polymer to 10~50 mL of water, and then stir at 50~100 °C to dissolve it, to obtain an aqueous solution of the polymer; dissolve acrylic acid and sulfobetaine in the aqueous solution of the polymer, and stir to obtain a monomer mixture.

[0040] The ratio of acrylic acid, sulfobetaine, and the polymer is (1~3) mL:(0.1~2) g:(0.1~1) g. The ratio of acrylic acid, sulfobetaine, NN methylenebisacrylamide, and the initiator is (1~3) mL:(0.1~2) g:(0.01~0.05) g:(0.01~0.1) g.

[0041] The polymer is at least one of polyvinyl alcohol, polyacrylamide, and sodium polyacrylate.

[0042] S2: Add NN methylenebisacrylamide to the monomer mixture, stir for 1-2 h, add initiator, continue stirring for 10-60 min, and then place the product at 40-60 °C for thermal polymerization for 3-6 h to obtain zwitterionic gel;

[0043] NN methylenebisacrylamide is used as a crosslinking agent.

[0044] The initiator is ammonium persulfate or potassium persulfate.

[0045] S3: Soak the zwitterionic gel in a 0.1-3 M (i.e., mol / L) ionic solution for 1-2 days, and then swell the product in a 3-6 M potassium hydroxide solution for 1-2 days to obtain the zwitterionic gel electrolyte.

[0046] The ionic solution is at least one of zinc sulfate solution, sodium sulfate, and sodium citrate.

[0047] In addition, the present invention also discloses a zwitterionic gel electrolyte prepared by the above method, and a zinc-air battery containing the zwitterionic gel electrolyte.

[0048] The zwitterionic gel electrolyte exhibits an ionic conductivity of 250–310 mS / cm and a tensile strength of 20–50 kPa. The open-circuit voltage of this zinc-air battery is 1.40–1.43 V.

[0049] The process for testing ionic conductivity is as follows:

[0050] The ionic conductivity was calculated using electrochemical impedance spectroscopy (EIS). The EIS was performed using an electrochemical workstation (CH760E, Shanghai Chenhua Instruments), with a frequency range of 100 kHz to 0.1 Hz and a voltage amplitude of 5 mV. The solid electrolyte was clamped between two stainless steel plates to measure the electrochemical impedance spectroscopy, and the conductivity was calculated using the following formula:

[0051]

[0052] in d and A These represent the thickness and surface area of ​​the electrolyte, respectively. R b This represents the electrolyte volume resistivity related to the X-axis intersection point in the electrochemical impedance spectroscopy.

[0053] The tensile strength test procedure is as follows:

[0054] The mechanical properties of the gel electrolyte were studied by performing a tensile test on the sample. The tensile rate was set at 10 mm / min, and the test ended when the sample broke.

[0055] The test procedure for open-circuit voltage is as follows:

[0056] This gel was used to assemble a zinc-air battery, and the open-circuit voltage during operation was measured using an electrochemical workstation.

[0057] This invention utilizes the zwitterionic groups of sulfobetaine to form ion channels and introduces polyvinyl alcohol as a second network to enhance the mechanical properties of the gel through the Hofmeister effect. The resulting honeycomb-like structure can adsorb a large amount of electrolyte solution and exhibits excellent hydration. This ultimately yields a superior gel electrolyte material. The -COO group in the gel electrolyte is utilized... - polar groups and -SO3 - The zinc-philic effect of the radical on the Zn anode inhibits the formation of Zn dendrites. Polarized -COO - The strong hydrogen bonds between the functional groups and water molecules, along with the electrostatically induced hydration of the zwitterionic functional groups, can prevent the gel electrolyte from freezing at low temperatures and evaporating at high temperatures, thereby increasing the battery's operating temperature range.

[0058] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0059] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0060] Example 1

[0061] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0062] a. Weigh 0.1 g of polyvinyl alcohol using an electronic balance, dissolve it in 10 mL of deionized water, and place it in an oil bath at 95 ℃. Stir thoroughly until dissolved, and record this as solution A.

[0063] b. Dissolve 2 mL of acrylic acid and 0.5 g of sulfobetaine in solution A, and stir thoroughly to mix them evenly. This solution is called solution B.

[0064] c. While stirring, add 0.01 g of N-N-methylenebisacrylamide to B and stir for 1 h. Then add 0.05 g of ammonium persulfate and continue stirring for 10 min. Then place in a 60 ℃ oven to polymerize for 3 h to form a gel.

[0065] d. Immerse the polymerized gel in a 2 M zinc sulfate solution for 2 days, then swell the soaked gel in a 6 M potassium hydroxide solution to form a solid electrolyte.

[0066] Example 2

[0067] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0068] a. Weigh 0.1 g of polyvinyl alcohol using an electronic balance, dissolve it in 10 mL of deionized water, and place it in an oil bath at 95 ℃. Stir thoroughly until dissolved, and record this as solution A.

[0069] b. Dissolve 2 mL of acrylic acid and 1 g of sulfobetaine in solution A, and stir thoroughly to mix them evenly. This solution is called solution B.

[0070] c. While stirring, add 0.01 g of N-N-methylenebisacrylamide to B and stir for 1 h. Then add 0.05 g of ammonium persulfate and continue stirring for 10 min. Then place in a 60 ℃ oven to polymerize for 3 h to form a gel.

[0071] d. Immerse the polymerized gel in a 2 M zinc sulfate solution for 2 days, then swell the soaked gel in a 6 M potassium hydroxide solution to form a solid electrolyte.

[0072] Example 3

[0073] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0074] a. Weigh 0.1 g of polyvinyl alcohol using an electronic balance, dissolve it in 10 mL of deionized water, and place it in an oil bath at 95 ℃. Stir thoroughly until dissolved, and record this as solution A.

[0075] b. Dissolve 2 mL of acrylic acid and 1.5 g of sulfobetaine in solution A, stir thoroughly to mix evenly, and record this as solution B.

[0076] c. While stirring, add 0.01 g of N-N-methylenebisacrylamide to B and stir for 1 h. Then add 0.05 g of ammonium persulfate and continue stirring for 10 min. Then place in a 60 ℃ oven to polymerize for 3 h to form a gel.

[0077] d. Immerse the polymerized gel in a 2 M zinc sulfate solution for 2 days, then swell the soaked gel in a 6 M potassium hydroxide solution to form a solid electrolyte.

[0078] Example 4

[0079] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0080] S1: Add 0.1 g of polyvinyl alcohol to 10 mL of water, and then stir at 50 °C to dissolve it, to obtain an aqueous solution of polyvinyl alcohol; dissolve acrylic acid and sulfobetaine in the aqueous solution of polyvinyl alcohol, and stir to obtain a monomer mixture;

[0081] The ratio of acrylic acid, sulfobetaine, and polyvinyl alcohol is 1 mL: 0.1 g: 0.1 g.

[0082] S2: Add NN methylenebisacrylamide as a crosslinking agent to the monomer mixture, stir for 1 h, add ammonium persulfate, continue stirring for 10 min, and then place the product at 40 ℃ for thermal polymerization for 6 h to obtain zwitterionic gel.

[0083] The ratio of acrylic acid, sulfobetaine, N,N-methylenebisacrylamide, and ammonium persulfate is 1 mL: 0.1 g: 0.01 g: 0.01 g.

[0084] S3: The zwitterionic gel was soaked in a 0.1 M zinc sulfate solution for 1 day, and the product was swollen in a 3 M potassium hydroxide solution for 1 day to obtain the zwitterionic gel electrolyte.

[0085] In addition, the present invention also discloses a zwitterionic gel electrolyte prepared by the above method, and a zinc-air battery containing the zwitterionic gel electrolyte.

[0086] The zwitterionic gel electrolyte has an ionic conductivity of 250 mS / cm and a tensile strength of 20 kPa. The open-circuit voltage of the zinc-air battery is 1.40 V.

[0087] Example 5

[0088] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0089] S1: Add 1 g of polyacrylamide to 50 mL of water, and then stir at 100 °C to dissolve it, to obtain an aqueous solution of the polyacrylamide; dissolve acrylic acid and sulfobetaine in the aqueous solution of polyacrylamide, and stir to obtain a monomer mixture;

[0090] The ratio of acrylic acid, sulfobetaine, and polyacrylamide is 3 mL: 2 g: 1 g.

[0091] S2: Add NN methylenebisacrylamide as a crosslinking agent to the monomer mixture, stir for 2 h, add potassium persulfate, continue stirring for 60 min, and then place the product at 60 ℃ for thermal polymerization for 3 h to obtain zwitterionic gel.

[0092] The ratio of acrylic acid, sulfobetaine, N,N-methylenebisacrylamide, and potassium persulfate is 3 mL: 2 g: 0.05 g: 0.1 g.

[0093] S3: The zwitterionic gel was soaked in 3 M sodium sulfate for 2 days, and the product was swollen in 6 M potassium hydroxide solution for 2 days to obtain the zwitterionic gel electrolyte.

[0094] In addition, the present invention also discloses a zwitterionic gel electrolyte prepared by the above method, and a zinc-air battery containing the zwitterionic gel electrolyte.

[0095] The zwitterionic gel electrolyte has an ionic conductivity of 310 mS / cm and a tensile strength of 50 kPa. The open-circuit voltage of the zinc-air battery is 1.43 V.

[0096] Example 6

[0097] A method for preparing a zwitterionic gel electrolyte includes the following steps:

[0098] S1: Add 0.5 g of sodium polyacrylate to 30 mL of water, and then stir at 80 °C to dissolve it, thus obtaining an aqueous solution of sodium polyacrylate; dissolve acrylic acid and sulfobetaine in the aqueous solution of sodium polyacrylate and stir to obtain a monomer mixture;

[0099] The ratio of acrylic acid, sulfobetaine, and sodium polyacrylate is 2 mL: 1 g: 0.5 g.

[0100] S2: Add NN methylenebisacrylamide as a crosslinking agent to the monomer mixture, stir for 1.5 h, add ammonium persulfate, continue stirring for 30 min, and then place the product at 50 ℃ for thermal polymerization for 5 h to obtain zwitterionic gel.

[0101] The ratio of acrylic acid, sulfobetaine, N,N-methylenebisacrylamide, and ammonium persulfate is 2 mL: 1 g: 0.02 g: 0.05 g.

[0102] S3: The zwitterionic gel was soaked in 2 M sodium citrate for 1.5 days, and the product was swollen in 4 M potassium hydroxide solution for 1.5 days to obtain the zwitterionic gel electrolyte.

[0103] In addition, the present invention also discloses a zwitterionic gel electrolyte prepared by the above method, and a zinc-air battery containing the zwitterionic gel electrolyte.

[0104] The zwitterionic gel electrolyte has an ionic conductivity of 300 mS / cm and a tensile strength of 30 kPa. The open-circuit voltage of the zinc-air battery is 1.41 V.

[0105] Figure 1 The bar chart shows the conductivity of the zwitterionic gel electrolytes prepared in Examples 1-3 of this invention. As can be seen from the figure, the zwitterionic gel electrolytes prepared in this invention have high conductivity, reaching up to 304 mS / cm.

[0106] Figure 2 The figures show the stress-strain curves of the zwitterionic gel electrolytes prepared in Examples 1-3 of this invention. As can be seen from the figures, the zwitterionic gel electrolytes prepared in this invention have good tensile strength and can meet the general application scenarios of solid-state zinc-air batteries.

[0107] Figure 3 is a scanning electron microscope image of the zwitterionic gel electrolyte prepared in Example 2 of the present invention. As can be seen from the figure, the zwitterionic gel electrolyte prepared in the present invention has a uniform porous structure, which is beneficial to the transport of ions in the solid electrolyte and effectively improves the ionic conductivity.

[0108] Figure 4 shows the open-circuit voltage of the flexible zinc-air battery assembled using the zwitterionic gel electrolyte prepared in Example 2 of this invention. Open-circuit voltage is an important indicator of battery performance, reflecting the potential difference between the positive and negative electrodes when the battery is in an open-circuit state (i.e., when the battery is not connected to a circuit and no current flows). A high open-circuit voltage means that chemical energy can be converted into electrical energy more effectively during battery discharge, thereby improving the battery's energy conversion efficiency. Simultaneously, under the same conditions, a battery with a high open-circuit voltage can provide higher output power, meeting the needs of applications with higher energy demands. Furthermore, the zwitterionic gel electrolyte has high ion conductivity, which can more effectively promote the migration and diffusion of ions inside the battery, thereby increasing the battery's open-circuit voltage. This gel electrolyte may have a more stable three-dimensional network structure, maintaining good stability and mechanical strength during battery charging and discharging, thus supporting a higher open-circuit voltage. As shown in the figure, the open-circuit voltage of the flexible zinc-air battery assembled using the zwitterionic gel electrolyte prepared in this invention is as high as 1.428V, far exceeding that of common PVA gel electrolytes.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a zwitterionic gel electrolyte, characterized in that, Includes the following steps: S1: Dissolve acrylic acid and sulfobetaine in an aqueous solution of a polymer and stir to obtain a monomer mixture; the polymer is at least one of polyvinyl alcohol, polyacrylamide, and sodium polyacrylate. S2: Add NN methylenebisacrylamide to the monomer mixture, stir evenly, add initiator, continue stirring to react, and then thermally polymerize the product to obtain zwitterionic gel; S3: After soaking the zwitterionic gel in an ionic solution, the product is swollen in a potassium hydroxide solution to obtain the zwitterionic gel electrolyte. The ionic solution is at least one of zinc sulfate solution, sodium sulfate and sodium citrate; The ratio of acrylic acid, sulfobetaine, and polymer is (1~3) mL:(0.1~2) g:(0.1~1) g; The ratio of acrylic acid, sulfobetaine, N,N-methylenebisacrylamide and the initiator is (1~3)mL:(0.1~2)g:(0.01~0.05)g:(0.01~0.1)g.

2. The method for preparing a zwitterionic gel electrolyte according to claim 1, characterized in that, The preparation process of the aqueous solution of the polymer is as follows: 0.1~1 g of polymer is added to 10~50 mL of water, and then stirred at 50~100 °C to dissolve it, thereby obtaining the aqueous solution of the polymer.

3. The method for preparing a zwitterionic gel electrolyte according to claim 1, characterized in that, Add NN methylenebisacrylamide to the monomer mixture, stir for 1-2 h, then add the initiator and continue stirring for 10-60 min.

4. The method for preparing a zwitterionic gel electrolyte according to claim 1, characterized in that, During the thermal polymerization process, the temperature is 40~60 ℃ and the time is 3~6 h.

5. The method for preparing a zwitterionic gel electrolyte according to claim 1, characterized in that, The concentration of the ionic solution is 0.1~3 M, and the zwitterionic gel is immersed in the ionic solution for 1~2 days.

6. The method for preparing a zwitterionic gel electrolyte according to claim 1, characterized in that, The concentration of the potassium hydroxide solution is 3-6 M, and the swelling treatment time is 1-2 days.

7. A zwitterionic gel electrolyte, characterized in that, The amphoteric gel electrolyte is prepared by the method described in any one of claims 1 to 6; the ionic conductivity of the amphoteric gel electrolyte is 250 to 310 mS / cm; and the tensile strength is 20 to 50 kPa.

8. A zinc-air battery, characterized in that, It includes a zwitterionic gel electrolyte as described in claim 7; the open-circuit voltage of the zinc-air battery is 1.40~1.43V.

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