Double-network hydrogel with high ionic conductivity as well as preparation method and application of double-network hydrogel

Abstract

The invention provides double-network hydrogel with high ionic conductivity as well as a preparation method and application of the double-network hydrogel, and belongs to the technical field of hydrogel. According to the invention, polyvinyl alcohol (PVA) and poly (3, 4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) are utilized to form a porous dual-network structure, so that ion conduction is more facilitated, and the conductivity of the hydrogel is enhanced. Besides, by controlling the adding proportion of the PVA, the zinc sulfate, the water, the PEDOT: PSS aqueous solution and the alkali liquor, the PVA, the alkali, the zinc sulfate and the like are uniformly distributed in the hydrogel while the ionic conductivity of the PVA-based hydrogel is improved. The result of the embodiment shows that the ionic conductivity of the prepared dual-network hydrogel is 180 mS / cm or above, the specific capacity of the prepared zinc-air battery is 549.88 mAh / g or above, and the charge-discharge cycle time under the current density of 2 mA / cm < 2 > is 33 h or above.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogels, and particularly relates to a double-network hydrogel with high ionic conductivity, a preparation method thereof, and an application thereof. Background Art

[0002] Flexible energy storage systems have attracted much attention in recent years to meet the rapidly growing demands of flexible and wearable electronic devices. Currently popular lithium-based batteries are difficult to meet the requirements of flexible wearable energy storage devices due to safety issues. Aqueous batteries, such as zinc-air batteries or zinc-ion batteries, have advantages such as environmental protection, safety, low cost, flexibility potential, and high energy density, and are expected to replace lithium-based batteries. However, traditional aqueous batteries based on liquid electrolytes still face problems such as volatilization and leakage, which hinder their application as flexible and wearable devices. Replacing traditional liquid electrolytes with solid electrolytes is the key core to realizing the transformation of the battery structure from conventional to flexible. Based on polymer network-encapsulated aqueous hydrogels, due to their high water content and mechanical flexibility, they are considered promising solid electrolytes, which guarantee the basic requirements of flexible aqueous energy devices. However, the development of high-performance hydrogel electrolytes requires reasonable design to meet the key requirements of specific energy devices.

[0003] Hydrogel networks have strong mechanical flexibility, high alkali tolerance, and high ionic conductivity, and are an ideal choice for hydrogel electrolytes used in alkaline aqueous energy devices, such as zinc-air batteries. However, the application of traditional polyvinyl alcohol (PVA)-based hydrogel electrolytes in zinc-air batteries is limited by relatively low ionic conductivity, poor alkali resistance, and poor flexibility. Therefore, it is necessary to develop an electrolyte with high ionic conductivity and strong alkali resistance.

[0004] Double-network hydrogel electrolyte materials have been widely discussed as efficient electrolytes for fuel cells or metal-air batteries. Due to their high ionic conductivity, high mechanical strength, good mechanical properties, antibacterial properties, and biocompatibility, etc., they have been proven to be an effective electrolyte. However, the ionic conductivity of traditional PVA-based double-network hydrogels still needs to be further improved, and there are problems of incompatibility between PVA and alkali and incompatibility between PVA and zinc sulfate. Therefore, synthesizing a double-network hydrogel with high ionic conductivity and uniform distribution of PVA with alkali and PVA with zinc sulfate is of great significance for improving the ionic conductivity and cycle life of solid-state zinc-air batteries. Summary of the Invention

[0005] The purpose of the present invention is to provide a double-network hydrogel with high ionic conductivity, a preparation method thereof, and an application thereof. The double-network hydrogel prepared by the present invention has higher ionic conductivity, and each component is uniformly distributed in the hydrogel. The zinc-air battery composed of it has properties such as high specific capacity.

[0006] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a double-network hydrogel with high ionic conductivity, which is as follows:

[0008] Mix polyvinyl alcohol, zinc sulfate, water, PEDOT:PSS aqueous solution and alkali solution, and then freeze and thaw to obtain a double-network hydrogel with high ionic conductivity;

[0009] The mass ratio of the polyvinyl alcohol to the zinc sulfate is 1:(0.03 - 0.09);

[0010] The mass concentration of the PEDOT:PSS aqueous solution is 1 - 2%, and the mass ratio of the polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:(100 - 300) μL; the mass ratio of the alkali in the alkali solution to the zinc sulfate is (18 - 22):1; the mass ratio of the polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL.

[0011] Preferably, the mass ratio of the polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL.

[0012] Preferably, the concentration of the alkali solution is 6 - 20 mol / L.

[0013] Preferably, the freezing temperature is -15 - -25 °C, and the freezing time is 12 - 48 h.

[0014] The present invention also provides a double-network hydrogel with high ionic conductivity prepared by the preparation method described in the above technical solutions.

[0015] The present invention also provides an application of the double-network hydrogel with high ionic conductivity described in the above technical solutions in a zinc-air battery.

[0016] The present invention provides a method for preparing a double-network hydrogel with high ionic conductivity, which is as follows: mixing polyvinyl alcohol, zinc sulfate, water, PEDOT:PSS aqueous solution and alkali solution, then freezing and thawing to obtain a double-network hydrogel with high ionic conductivity; the mass ratio of polyvinyl alcohol to zinc sulfate is 1:(0.03 - 0.09); the mass concentration of the PEDOT:PSS aqueous solution is 1 - 2%, and the mass ratio of polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:(100 - 300) μL; the mass ratio of the alkali in the alkali solution to zinc sulfate is (18 - 22):1; the mass ratio of polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL. The present invention utilizes PVA and PEDOT:PSS to form a porous double-network structure, and the porous double-network structure is more conducive to ion conduction, enhancing the conductivity of the hydrogel. At the same time, the ions ionized by PEDOT:PSS, alkali and zinc sulfate, these salts with good water solubility in water, enhance the conductivity of the hydrogel; in addition, by controlling the addition ratios of PVA, PEDOT:PSS, water, alkali solution and zinc sulfate, a double-network hydrogel based on PVA with high ionic conductivity is prepared, which not only solves the problem of low ionic conductivity of traditional PVA-based hydrogels, but also solves the problem of uneven distribution of PVA, alkali and zinc sulfate in the hydrogel, thereby enabling the zinc-air battery using this double-network hydrogel as a gel electrolyte to have excellent electrochemical performance. The results of the examples show that the components in the double-network hydrogel prepared by the present invention are evenly distributed, the ionic conductivity is above 180 mS / cm, the specific capacity of the prepared zinc-air battery is above 549.88 mAh / g, and the charge-discharge cycle time is above 33 h at a current density of 2 mA / cm 2 The charge-discharge cycle time is above 33 h at a current density of 2 mA / cm Description of the Drawings

[0017] Figure 1 It is the mapping diagram of the hydrogel prepared in Example 1;

[0018] Figure 2 It is the SEM diagram of the hydrogel prepared in Example 1 at different magnification multiples;

[0019] Figure 3 It is the differential scanning calorimeter (DSC) diagram of the hydrogel prepared in Example 1;

[0020] Figure 4 It is the alkali resistance diagram of the hydrogels prepared in Example 1 and Comparative Example 1;

[0021] Figure 5 It is the electrochemical impedance spectroscopy diagram of the hydrogels prepared in Examples 1 - 3;

[0022] Figure 6 It is the electrochemical impedance spectroscopy diagram of the hydrogels of Example 1 and Comparative Example 1;

[0023] Figure 7 Electrochemical impedance diagrams of the hydrogel prepared in Example 1 and the hydrogel prepared in Example 1 after being soaked in 18 mol / L potassium hydroxide solution for 1 h;

[0024] Figure 8 Adhesion diagram of the hydrogel prepared in Example 1 to carbon cloth and zinc sheet;

[0025] Figure 9 Charge-discharge cycle diagrams of zinc-air batteries assembled with the hydrogels prepared in Examples 1 to 3;

[0026] Figure 10 Charge-discharge cycle diagrams of zinc-air batteries assembled with the hydrogels prepared in Examples 1, 4 to 5;

[0027] Figure 11 Specific capacity diagrams of zinc-air batteries assembled with the hydrogels prepared in Example 1 and Comparative Example 1;

[0028] Figure 12 Charge-discharge cycle diagram of a zinc-air battery assembled after soaking the hydrogel prepared in Example 1 in 18 mol / L KOH solution for 1 h;

[0029] Figure 13 SEM diagram of the side of the zinc sheet after charge-discharge cycling of a zinc-air battery assembled with the double-network hydrogel prepared in Example 1;

[0030] Figure 14 Macrograph of a zinc-air battery assembled with the hydrogel prepared in Example 1. Detailed implementation mode

[0031] The present invention provides a preparation method of a double-network hydrogel with high ionic conductivity, which is as follows:

[0032] Mix polyvinyl alcohol, zinc sulfate, water, PEDOT:PSS aqueous solution and alkali solution, and then freeze and thaw to obtain a double-network hydrogel with high ionic conductivity;

[0033] The mass ratio of the polyvinyl alcohol to the zinc sulfate is 1:(0.03 - 0.09);

[0034] The mass concentration of the PEDOT:PSS aqueous solution is 1 - 2%, and the mass ratio of the polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:(100 - 300) μL; the mass ratio of the alkali in the alkali solution to the zinc sulfate is (18 - 22):1; the mass ratio of the polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL.

[0035] Unless otherwise specified, the present invention has no special limitation on the sources of various raw materials, and commercially available products well-known to those skilled in the art can be used.

[0036] In the present invention, the average molecular weight of the polyvinyl alcohol (PVA) is preferably 20,000 to 150,000; the polyvinyl alcohol is preferably type 1799 polyvinyl alcohol. By controlling the average molecular weight of PVA within the above range in the present invention, its better dissolution and the performance of the hydrogel can be improved.

[0037] In the present invention, the mass ratio of the polyvinyl alcohol to zinc sulfate is 1:(0.03 - 0.09). As an embodiment, the mass ratio of the polyvinyl alcohol to zinc sulfate can specifically be 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, or 1:0.09. By controlling the mass ratio of the polyvinyl alcohol to zinc sulfate within the above range in the present invention, the ionic conductivity of the hydrogel can be further improved.

[0038] In the present invention, the water is preferably deionized water.

[0039] In the present invention, the mass ratio of the polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL. As an embodiment, the mass ratio of the polyvinyl alcohol to the volume of water can specifically be 1.7 g:10 mL, 1.7 g:15 mL, 1.7 g:20 mL, 1.7 g:25 mL, or 1.7 g:30 mL. By controlling the mass ratio of the polyvinyl alcohol to the volume of water within the above range in the present invention, the raw materials can be fully dissolved.

[0040] In the present invention, the mass concentration of the PEDOT:PSS aqueous solution is 1 - 2%. As an embodiment, the mass concentration of the PEDOT:PSS aqueous solution can specifically be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%.

[0041] In the present invention, the mass ratio of the polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:(100 - 300) μL. As an embodiment, the mass ratio of the polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution can specifically be 1.7 g:100 μL, 1.7 g:150 μL, 1.7 g:200 μL, 1.7 g:250 μL, or 1.7 g:300 μL. By controlling the mass ratio of the polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution within the above range in the present invention, the ionic conductivity of the hydrogel can be further improved and the elements can be evenly distributed in the hydrogel.

[0042] In the present invention, the alkaline solution preferably comprises an aqueous solution of potassium hydroxide or an aqueous solution of sodium hydroxide.

[0043] In the present invention, the concentration of the alkaline solution is preferably 6 - 20 mol / L. As an embodiment, the concentration of the alkaline solution can specifically be 6 mol / L, 8 mol / L, 10 mol / L, 12 mol / L, 15 mol / L, 16 mol / L, 17 mol / L, 18 mol / L, 19 mol / L or 20 mol / L.

[0044] In the present invention, the mass ratio of the alkali in the alkaline solution to zinc sulfate is (18 - 22):1. As an embodiment, the mass ratio of the alkali in the alkaline solution to zinc sulfate can specifically be 18:1, 19:1, 20:1, 21:1 or 22:1. By controlling the concentration and dosage of the alkaline solution within the above ranges in the present invention, the ionic conductivity of the hydrogel can be further improved.

[0045] In the present invention, the mixing of polyvinyl alcohol, zinc sulfate, water, PEDOT:PSS aqueous solution and alkaline solution is preferably as follows: Mix polyvinyl alcohol, zinc sulfate and water, stir and dissolve at 90 - 100 °C, then add the PEDOT:PSS aqueous solution and continue stirring, and then add the alkaline solution at 50 - 95 °C and stir until the solution becomes transparent. By adopting the mixing method of the present invention, the components can be mixed more uniformly. The present invention has no special limitations on the mixing method, rate and time, and the mixing technical solutions well-known to those skilled in the art can be adopted to ensure that all raw materials are fully dissolved.

[0046] In the present invention, the freezing temperature is preferably -15 to -25 °C. As an embodiment, the freezing temperature can specifically be -15 °C, -16 °C, -17 °C, -18 °C, -19 °C, -20 °C, -21 °C, -22 °C, -23 °C, -24 °C or -25 °C.

[0047] In the present invention, the freezing time is preferably 12 - 48 h. As an embodiment, the freezing time can specifically be 12 h, 15 h, 18 h, 20 h, 25 h, 30 h, 35 h, 40 h, 42 h, 45 h or 48 h. By controlling the freezing temperature and time within the above ranges in the present invention, the hydrogel can be fully formed.

[0048] In the present invention, the thawing temperature is preferably 20 - 30 °C, more preferably 25 °C; the thawing time is preferably 20 - 60 min, more preferably 30 min.

[0049] The present invention controls the types and dosages of various raw materials, which not only solves the problem of low ionic conductivity of traditional PVA-based hydrogels, but also solves the problem of uneven distribution of PVA, alkali, zinc sulfate, etc. in the hydrogel. At the same time, the alkali resistance of the hydrogel is improved, so that the zinc-air battery using this double-network hydrogel as a gel electrolyte has excellent electrochemical performance.

[0050] The present invention also provides a double-network hydrogel with high ionic conductivity prepared by the preparation method described in the above technical solution.

[0051] The double-network hydrogel prepared by the present invention has more excellent ionic conductivity.

[0052] The present invention also provides the application of the double-network hydrogel with high ionic conductivity described in the above technical solution in a zinc-air battery.

[0053] In the present invention, the double-network hydrogel serves as the electrolyte of the zinc-air battery. Since the double-network hydrogel prepared by the present invention has higher ionic conductivity, the zinc-air battery has excellent electrochemical performance.

[0054] The present invention has no special limitations on the positive electrode, negative electrode and preparation method of the zinc-air battery, and the technical solutions well-known to those skilled in the art can be adopted.

[0055] The present invention has no special limitations on the operation of the application, and the technical solutions of the application well-known to those skilled in the art can be adopted.

[0056] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0057] Example 1

[0058] A preparation method of a double-network hydrogel with high ionic conductivity is as follows: Add 1.7 g of polyvinyl alcohol of type 1799 (average molecular weight 75535) and zinc sulfate (the mass ratio of polyvinyl alcohol to zinc sulfate is 1:0.06) to 20 mL of deionized water (the mass ratio of polyvinyl alcohol to the volume of deionized water is 1.7 g:20 mL), stir and dissolve at 95 °C, then add 200 μL of a 1.5% PEDOT:PSS aqueous solution (the mass ratio of polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:200 μL) and continue stirring, and then add an 18 mol / L potassium hydroxide solution at 95 °C (the mass ratio of potassium hydroxide in the potassium hydroxide solution to zinc sulfate is 20:1), stir until the solution becomes transparent, place it in the refrigerator and freeze at -20 °C for 12 h, and then thaw at 25 °C for 30 min to obtain a double-network hydrogel with high ionic conductivity.

[0059] The mapping diagram of the hydrogel prepared in Example 1 is as Figure 1 shown. It can be seen from Figure 1 that the hydrogel has a porous structure and various elements are uniformly distributed in the hydrogel.

[0060] The SEM diagrams of the hydrogel prepared in Example 1 at different magnification factors are as Figure 2 shown. It can be seen from Figure 2 that the hydrogel has a porous structure.

[0061] The differential scanning calorimeter (DSC) diagram of the hydrogel prepared in Example 1 is as Figure 3 shown. It can be seen from Figure 3 that the phase transition temperature of the hydrogel is below -10 °C, indicating a characteristic of the hydrogel's low-temperature resistance. Due to the presence of zinc sulfate, the phase transition temperature of the hydrogel is reduced.

[0062] Example 2

[0063] Replace the mass ratio of polyvinyl alcohol to zinc sulfate in Example 1 with 1:0.03, and keep other parameters the same as those in Example 1.

[0064] Example 3

[0065] Replace the mass ratio of polyvinyl alcohol to zinc sulfate in Example 1 with 1:0.09, and keep other parameters the same as those in Example 1.

[0066] Example 4

[0067] Replace the dosage of the PEDOT:PSS aqueous solution in Example 1 with 100 μL. At this time, the mass ratio of polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:100 μL, and keep other parameters the same as those in Example 1.

[0068] Example 5

[0069] Replace the dosage of the PEDOT:PSS aqueous solution in Example 1 with 300 μL. At this time, the mass ratio of polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:300 μL, and other parameters are the same as those in Example 1.

[0070] Comparative Example 1

[0071] Omit the PEDOT:PSS aqueous solution and zinc sulfate in Example 1 to obtain a hydrogel.

[0072] Comparative Example 2

[0073] Omit the PEDOT:PSS aqueous solution in Example 1 to obtain a hydrogel.

[0074] Immerse the hydrogels prepared in Example 1 and Comparative Example 1 in 1 mol / L KOH solution for 7 days. Calculate the alkali resistance of the hydrogels based on the mass of the hydrogels before and after immersion. The results are as Figure 4 shown, where PVA is Comparative Example 1, and PVAPP ZnSO4 is Example 1 (PP refers to PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate)). As can be seen from Figure 4 this, the mass of the hydrogel in Comparative Example 1 increased by 60% after immersion, while the mass of the hydrogel in Example 1 increased by 3% after immersion, proving that the hydrogel prepared by the present invention has better alkali resistance.

[0075] Insert a copper rod into the interior of the hydrogel. At the electrochemical workstation A.C. Impedace (alternating current impedance test), set the initial voltage to -0.05 V, the test frequency range to 10 - 100000 Hz, and the amplitude to 5 mV. Test the ionic conductivity of the hydrogels prepared in Examples 1 - 5 and Comparative Examples 1 - 2. The results are shown in Table 1, and the electrochemical impedance spectra of the hydrogels prepared in Examples 1 - 3 are as Figure 5 shown. Figure 5 In this, 9 wt% ZnSO4 is Example 3, 3 wt% ZnSO4 is Example 2, and 6 wt% ZnSO4 is Example 1.

[0076] The electrochemical impedance spectra of the hydrogels in Example 1 and Comparative Example 1 are as Figure 6 shown. Figure 6 In this, PVA is Comparative Example 1, and PVAPPZnSO4 is Example 1.

[0077] The electrochemical impedance diagrams of the hydrogel prepared in Example 1 and the hydrogel prepared in Example 1 after being immersed in 18 mol / L potassium hydroxide solution for 1 h are as Figure 7 shown. Figure 7In this case, PVAPPZnSO4 is Example 1, and 18MKOH is after the hydrogel prepared in Example 1 is soaked in 18 mol / L potassium hydroxide solution for 1 h.

[0078] Table 1 shows the ionic conductivities of the hydrogels prepared in Examples 1-5 and Comparative Examples 1-2

[0079]

[0080] As can be seen from Table 1 and Figures 5 - 6 it can be seen that the ionic conductivity of the hydrogel prepared by the present invention is above 180 mS / cm. From Figure 7 it can be seen that after the hydrogel prepared in Example 1 is soaked in 18 mol / L potassium hydroxide solution for 1 h, the ionic conductivity of the hydrogel decreases, but it can still reach 150 mS / cm.

[0081] Application Example

[0082] Using carbon cloth loaded with Pt / Ir / C catalyst as the positive electrode, zinc sheet as the negative electrode, and the hydrogels prepared in Examples 1-5 and Comparative Examples 1-2 as the electrolyte, zinc-air batteries are prepared.

[0083] The adhesion of the hydrogel prepared in Example 1 to the carbon cloth and zinc sheet is as Figure 8 shown, where the left figure is the carbon cloth and the right figure is the zinc sheet. From Figure 8 it can be seen that the hydrogel prepared by the present invention has a certain viscosity to both the cathode and anode of the zinc-air battery, increasing the stability of the battery connection.

[0084] The charge-discharge cycle diagrams of the zinc-air batteries assembled with the hydrogels prepared in Examples 1-3 are as Figure 9 shown, where 9wt% ZnSO4 is Example 3, 3wt% ZnSO4 is Example 2, and 6wt% ZnSO4 is Example 1. From Figure 9 it can be seen that the charge-discharge cycle time of the zinc-air battery assembled with the hydrogel prepared in Example 1 is longer and more stable.

[0085] The charge-discharge cycle diagrams of the zinc-air batteries assembled with the hydrogels prepared in Examples 1, 4-5 are as Figure 10 shown, where 300 μL PP is Example 5, 200 μL PP is Example 1, and 100 μL PP is Example 4. From Figure 10 it can be seen that the charge-discharge cycle time of the zinc-air battery assembled with the hydrogel prepared in Example 1 is longer and more stable.

[0086] The specific capacities of the zinc-air batteries assembled with the hydrogels prepared in Example 1 and Comparative Example 1 are as Figure 11 shown, where PVA is Comparative Example 1 and PVAPP ZnSO4 is Example 1. FromFigure 11 It can be seen that the specific capacity of the hydrogel prepared by the present invention is higher.

[0087] Test the specific capacity of the zinc-air batteries assembled with the hydrogels prepared in Test Examples 1 to 5 and Comparative Example 1, and the charge-discharge cycle time at a current density of 2 mA / cm 2 The results are shown in Table 2.

[0088] Table 2 Specific capacity of the zinc-air batteries assembled with the hydrogels prepared in Examples 1 to 5 and Comparative Example 1, and charge-discharge cycle time at a current density of 2 mA / cm 2 The charge-discharge cycle time at a current density of

[0089]

[0090] Test the charge-discharge cycle time of the zinc-air battery assembled with the hydrogel prepared in Comparative Example 2 at a current density of 2 mA / cm 2 The charge-discharge cycle time is 24 h.

[0091] It can be seen from Table 2 that the zinc-air battery assembled with the double-network hydrogel prepared by the present invention has excellent specific capacity and long charge-discharge cycle time.

[0092] Test the power density of the zinc-air battery assembled with the double-network hydrogel prepared in Example 1, which is 110 mW / cm 2 , and the power density of the zinc-air battery assembled with the hydrogel prepared in Comparative Example 2 is 38.84 mW / cm 2 .

[0093] Immerse the hydrogel prepared in Example 1 in 18 mol / L KOH solution for 1 h and then assemble it into a zinc-air battery. Its charge-discharge cycle diagram is as Figure 12 shown. It can be seen from Figure 12 that the hydrogel prepared by the present invention can still work stably after being immersed in an alkaline solution, and the cycle is 45 h.

[0094] The SEM diagram of the side of the zinc sheet of the zinc-air battery assembled with the double-network hydrogel prepared in Example 1 after charge-discharge cycle is as Figure 13 shown. It can be seen from Figure 13 that zinc ions are uniformly deposited on the surface of the zinc sheet, and no zinc dendrites appear, which increases the service life of the battery.

[0095] The macroscopic diagram of the zinc-air battery assembled with the hydrogel prepared in Example 1 is as Figure 14 shown, where the voltage diagram of a zinc-air battery is in the upper left corner, the voltage diagram of two series-connected zinc-air batteries is in the upper right corner, two series-connected zinc-air batteries in the lower left corner can make the sign light up, and two series-connected zinc-air batteries in the lower right corner can make the diode light up.

[0096] In summary, the hydrogel prepared by the present invention has higher ionic conductivity, and the zinc-air battery assembled as an electrolyte has excellent specific capacity, power density and long charge-discharge cycle time.

[0097] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a double-network hydrogel with high ionic conductivity, characterized in that, It is as follows: Mix polyvinyl alcohol, zinc sulfate, water, PEDOT:PSS aqueous solution and alkali solution, then freeze and thaw to obtain a double-network hydrogel with high ionic conductivity; The mass ratio of the polyvinyl alcohol to the zinc sulfate is 1:(0.03 - 0.09); The mass concentration of the PEDOT:PSS aqueous solution is 1 - 2%, and the mass ratio of the polyvinyl alcohol to the volume of the PEDOT:PSS aqueous solution is 1.7 g:(100 - 300) μL; the mass ratio of the alkali in the alkali solution to the zinc sulfate is (18 - 22):1; the mass ratio of the polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the polyvinyl alcohol to the volume of water is 1.7 g:(10 - 30) mL.

3. The preparation method according to claim 1, characterized in that, The concentration of the alkali solution is 6 - 20 mol / L.

4. The preparation method according to claim 1, characterized in that, The temperature of the freezing is -15 - -25 °C, and the freezing time is 12 - 48 h.

5. A double-network hydrogel with high ionic conductivity prepared by the preparation method according to any one of claims 1 - 4.

6. Application of the double-network hydrogel with high ionic conductivity according to claim 5 in a zinc-air battery.

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