Modified sodium alginate cross-linked hydrogel electrolyte as well as preparation method and application thereof

Abstract

The invention relates to the technical field of hydrogel electrolyte, and particularly discloses modified sodium alginate cross-linked hydrogel electrolyte as well as a preparation method and application thereof. According to the invention, modified sodium alginate is introduced into the hydrogel electrolyte as a cross-linking agent, so that the environmental toxicity and pollution are reduced, interaction between sodium alginate and zinc ions is utilized to realize an inhibition effect on zinc dendrites, interface growth between a negative electrode and the electrolyte is adjusted, and the service life of a battery is further prolonged; meanwhile, a certain inhibition effect is also achieved on a hydrogen evolution reaction. The modified sodium alginate cross-linked hydrogel electrolyte can be prepared through a simple free radical polymerization method, and meanwhile, compared with a conventional aqueous battery, the hydrogel electrolyte can better regulate and control interface growth of a positive electrode and a negative electrode.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogel electrolytes, and in particular to a modified sodium alginate cross-linked hydrogel electrolyte and a preparation method and application thereof. Background Art

[0002] In order to improve the stability of Zn anode, some strategies have been proposed, such as constructing interfacial layers, adjusting electrolytes, and controlling the growth / deposition of specific crystal faces. For example, Wang et al. used highly conductive carbon fiber graphite felt (GF) as the current collector and electrodeposited zinc under constant voltage to fabricate a self-supporting Zn@GF anode. The Zn@GF electrode has a large specific surface area, which can reduce the local current density and achieve dendrite-free behavior. Chen et al. prepared an Ag nanoparticle-modified carbon cloth (AgNPs@CC). Due to the zinc affinity of Ag nanoparticles, the AgNPs@CC / Zn electrode exhibits lower overpotential and better cycling performance than the CC / Zn electrode. However, their expensive and complicated preparation processes usually pose significant obstacles to practical applications.

[0003] Aqueous zinc-ion batteries (AZIBs) are considered to be favorable candidates for lithium-ion batteries in large-scale energy storage due to their high safety, low cost, and environmental friendliness. However, the poor stability of zinc anode in slightly acidic systems limits the commercial application of AZIBs. The growth of zinc dendrites during zinc plating / stripping is the main obstacle to the development of high-stability Zn anodes. In particular, when the cycling capacity increases, zinc dendrites become extremely serious, resulting in battery short circuit.

[0004] In addition, the hydrogen evolution reaction of zinc is thermodynamically feasible in commonly used electrolytes, such as 2M ZnSO4 weak acid electrolyte. During the cycle, the battery will produce a large amount of hydrogen, which will destroy the battery structure and hinder the long cycle life of the battery. After the hydrogen evolution reaction occurs, OH- ions will aggregate, produce insoluble precipitation, cause corrosion, and seriously affect the coulombic efficiency.

[0005] Therefore, there is an urgent need for a hydrogel electrolyte that can inhibit zinc dendrites and hydrogen evolution reaction and has a simple preparation method. Summary of the invention

[0006] The purpose of the present application is to overcome the deficiencies of the above-mentioned prior art and to provide a modified sodium alginate cross-linked hydrogel electrolyte and a preparation method and application thereof.

[0007] To achieve the above purpose, the technical solution adopted by this application is:

[0008] The present application provides a method for preparing a modified sodium alginate cross-linked hydrogel electrolyte, comprising the following steps:

[0009] S1, dissolving acrylamide monomer in deionized water, and then adding ammonium persulfate and modified sodium alginate to obtain a mixed solution;

[0010] S2, adjusting the pH of the mixed solution obtained in step S1 to obtain a prepolymerization solution;

[0011] S3, degassing the prepolymerized solution, sealing it, and polymerizing it to obtain a hydrogel;

[0012] S4, immersing the hydrogel in an electrolyte to obtain a modified sodium alginate cross-linked hydrogel electrolyte;

[0013] The double bond structure of glycidyl methacrylate is grafted onto sodium alginate to form modified sodium alginate.

[0014] The hydrogel electrolyte provided in this application is a quasi-solid electrolyte composed of a cross-linked hydrophilic polymer to form a 3D network filled with a zinc salt aqueous solution, so that the hydrogel electrolyte has the advantages of high zinc ion conductivity and low interface resistance. 2+ Regulate the transport pathways of zinc deposition and inhibit zinc dendrite growth, ultimately extending the life of zinc-ion batteries.

[0015] Sodium alginate itself is a natural polysaccharide and is environmentally friendly; and sodium alginate itself can be extracted from natural organisms, saving costs. This application reduces environmental toxicity and pollution by introducing modified sodium alginate as a cross-linking agent in the hydrogel electrolyte, and utilizes the interaction between sodium alginate and zinc ions to achieve the inhibition of zinc dendrites, regulate the interface growth between the negative electrode and the electrolyte, and thus extend the battery life. At the same time, it also has a certain inhibitory effect on the hydrogen evolution reaction.

[0016] This application uses acrylamide as a monomer and ammonium persulfate as an initiator. The initiator decomposes under heat to produce free radicals, which can link the monomers into molecular chains, and the cross-linking agent can cross-link the molecular chains to form a hydrogel. This application can prepare a modified sodium alginate cross-linked hydrogel electrolyte through a simple free radical polymerization method. At the same time, compared with conventional aqueous batteries, the hydrogel electrolyte can better regulate the interface growth of the positive and negative electrodes.

[0017] In some specific embodiments, the prepolymerization solution is degassed to prevent the influence of oxygen on polymerization, added into a sealed mold, and polymerized at 60° C. for two hours to obtain a hydrogel; the hydrogel is immersed in an electrolyte for one day to obtain a hydrogel electrolyte.

[0018] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, the method for preparing the modified sodium alginate comprises the following steps:

[0019] 1) dissolving sodium alginate in deionized water to obtain a pre-liquid, and adjusting the pH of the pre-liquid to be alkaline to obtain a mixed solution;

[0020] 2) Glycidyl methacrylate is added to the mixed solution, mixed and stirred, and then precipitated, and then vacuum filtered, washed and freeze-dried to obtain modified sodium alginate.

[0021] The present application first modifies sodium alginate, and the added glycidyl methacrylate itself has a double bond structure, and the double bond structure of glycidyl methacrylate is grafted onto sodium alginate, so that sodium alginate has a double bond structure, and then acts as a cross-linking agent. The modified sodium alginate interacts with zinc ions, which can effectively inhibit the growth of zinc dendrites and regulate the interface growth between the negative electrode and the electrolyte; at the same time, it also has a certain inhibitory effect on the hydrogen evolution reaction, thereby extending the life of the zinc ion battery.

[0022] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, the ratio of the sodium alginate to glycidyl methacrylate is 4 g:0.675 μL.

[0023] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, the reagent for adjusting the pH of the pre-solution includes NaOH, and the pH of the pre-solution is 10-11.

[0024] In some specific embodiments, the method for preparing the modified sodium alginate comprises the following steps:

[0025] Using a 250mL three-necked flask, 4g of sodium alginate was dissolved in 100mL of deionized water, and stirring was continued until it was completely dissolved as a pre-liquid; 6M NaOH was prepared, and slowly added to the pre-liquid, and the pH of the pre-liquid was adjusted to 10, and continued to stir thoroughly for 15 minutes to obtain a mixed solution; then 0.675μL of glycidyl methacrylate (GMA) was added to the mixed solution, and stirred at a constant temperature of 60°C for 24h; an appropriate amount of ethanol was added to the solution after the reaction for precipitation, and a white product was obtained by vacuum filtration, which was washed with ethanol 2-3 times and freeze-dried to obtain modified sodium alginate.

[0026] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, the mass ratio of the ammonium persulfate to the modified sodium alginate is 1:(1-2).

[0027] In the technical solution of the present application, ammonium persulfate and modified sodium alginate are used as initiators and cross-linking agents. The present application adopts the modified sodium alginate added in the above amount to improve the swelling rate and water retention of the hydrogel electrolyte, thereby improving the life of the battery and reducing the battery capacity attenuation after multiple charge and discharge cycles.

[0028] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, the mass ratio of the ammonium persulfate to the modified sodium alginate is 3:5.

[0029] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, in step S2, the reagent for adjusting the pH of the mixed solution obtained in step S1 includes acrylic acid.

[0030] The present application adopts acrylic acid as a pH regulator for adjusting the mixed solution.

[0031] As a preferred embodiment of the method for preparing the modified sodium alginate cross-linked hydrogel electrolyte described in the present application, in step S4, the electrolyte includes ZnSO4.

[0032] The present application also provides a modified sodium alginate cross-linked hydrogel electrolyte prepared by the preparation method of the modified sodium alginate cross-linked hydrogel electrolyte.

[0033] The thickness of the modified sodium alginate cross-linked hydrogel electrolyte is 1 to 2 mm.

[0034] The present application also provides the use of modified sodium alginate cross-linked hydrogel electrolyte in the preparation of batteries.

[0035] The modified sodium alginate cross-linked hydrogel electrolyte prepared as described above is applied to batteries, which improves the capacity retention rate of the batteries, thereby increasing the life of the batteries and reducing the battery capacity attenuation after multiple charge and discharge cycles.

[0036] Compared with the prior art, this application has the following beneficial effects:

[0037] The present application provides a modified sodium alginate cross-linked hydrogel electrolyte and its preparation method and application. The present application reduces environmental toxicity and pollution by introducing modified sodium alginate as a cross-linking agent in the hydrogel electrolyte, and utilizes the interaction between sodium alginate and zinc ions to achieve the inhibition of zinc dendrites, regulate the interfacial growth between the negative electrode and the electrolyte, and thus extend the battery life; at the same time, it also has a certain inhibitory effect on the hydrogen evolution reaction, which can greatly extend the cycle life of the battery, which can be verified from the subsequent battery cycle test. The present application uses acrylamide as a monomer and ammonium persulfate as an initiator. The initiator decomposes under heat to produce free radicals, which can link the monomers into molecular chains, and the cross-linking agent can cross-link the molecular chains into hydrogels. The present application can prepare a modified sodium alginate cross-linked hydrogel electrolyte by a simple free radical polymerization method. At the same time, compared with conventional aqueous batteries, the hydrogel electrolyte can better regulate the interfacial growth of the positive and negative electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is the microscopic infrared spectra of modified sodium alginate, unmodified sodium alginate and GMA (glycidyl methacrylate);

[0039] Figure 2 This is a physical picture of the modified sodium alginate cross-linked hydrogel electrolyte prepared in Example 2;

[0040] Figure 3 This is a graph showing the electrochemical impedance test results of a symmetrical battery assembled using the hydrogel prepared in Example 2;

[0041] Figure 4 This is a graph showing the ionic conductivity results of the hydrogel prepared in Example 2;

[0042] Figure 5 The symmetrical battery assembled with the hydrogel prepared in Example 2 was -2 Current density and 1mAhcm -2 Cycling performance diagram under surface capacity;

[0043] Figure 6 The assembled symmetric battery of MBAA cross-linked hydrogel prepared in Comparative Example 1 was tested at 0.5 mA cm -2 Current density and 1mAh cm -2 Cycling performance diagram under surface capacity;

[0044] Figure 7 The symmetrical battery assembled with the hydrogel prepared in Example 2 was -2 Current density and 1mAhcm -2 Cycling performance diagram under surface capacity;

[0045] Figure 8 The rate performance diagram of a full battery assembled with the modified sodium alginate cross-linked hydrogel electrolyte prepared in Example 2 and manganese dioxide as the positive electrode at different current densities of 0.1c, 0.2c, 0.5c, 1c and 2c;

[0046] Fig. 9 This is a cycle performance diagram of a full battery assembled using the modified sodium alginate cross-linked hydrogel electrolyte prepared in Example 2 and manganese dioxide as the positive electrode at a current density of 0.5A g-1;

[0047] Fig.10 The application effects of the modified sodium alginate cross-linked hydrogel flexible battery prepared in Example 6 under different conditions

[0048] Fig.11 This is a schematic diagram of the principle of modified sodium alginate prepared in Example 1;

[0049] Fig.12The assembled symmetric battery of MBAA cross-linked hydrogel prepared in Comparative Example 1 was 1.5 mA cm -2 Current density and 1mAh cm -2 Cycling performance diagram under surface capacity;

[0050] Fig.13 The full battery assembled with MBAA cross-linked hydrogel electrolyte prepared in Comparative Example 1 and manganese dioxide as the positive electrode was tested at 0.5A g -1 Cycling performance diagram at current density of .

[0051] Fig.14 The swelling rate curves of the modified sodium alginate cross-linked hydrogels of different concentrations prepared in Examples 2 to 5 and the control hydrogels are shown.

[0052] Fig.15 The assembled symmetric battery of modified sodium alginate cross-linked hydrogels with different concentrations prepared in Examples 2 to 5 was 0.5 mA cm -2 Current density and 1mAh cm -2 Cycling performance diagram under surface capacity;

[0053] Fig.16 The assembled symmetric battery of modified sodium alginate cross-linked hydrogels with different concentrations prepared in Examples 1 to 5 was tested at 0.5 mA cm -2 Current density and 1mAh cm -2 Bar chart comparison of cycling performance at surface capacity. DETAILED DESCRIPTION

[0054] In order to better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0055] In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified, and the components and raw materials used in each parallel experiment are of the same type.

[0056] The present application uses 800-grit sandpaper to polish the zinc foil, and soaks the polished zinc foil in ethanol for 10 minutes for ultrasonic treatment to remove the oxide layer on the surface of the zinc foil. The zinc foil is cut into discs with a diameter of 14 mm for assembling the battery negative electrode.

[0057] The preparation of the manganese dioxide positive electrode sheet material used in this application is as follows:

[0058] Manganese dioxide, conductive carbon black, and binder PVDF were dissolved in NMP solvent at a ratio of 7:2:1. The concentration of PVDF and NMP solution was 20 mg mL -1. Ball milling at 400 rpm for 24 hours. Titanium foil was used as the current collector, the slurry was coated on the titanium foil, placed in a vacuum drying oven, and vacuum dried at 60°C for 20 hours. After drying, a cutting machine was used to cut the circular manganese dioxide positive electrode sheets with a diameter of 14 mm.

[0059] Example 1: Preparation of modified sodium alginate

[0060] This embodiment provides a method for preparing modified sodium alginate, comprising the following steps:

[0061] 1) Use a 250 mL three-necked flask to dissolve 4 g of sodium alginate in 100 mL of deionized water and continue stirring until completely dissolved as the pre-liquid.

[0062] 2) Prepare 6M NaOH, slowly add it to the pre-liquid, adjust the pH to 10, and continue to stir thoroughly for 15 minutes.

[0063] 3) Then, 0.675 μL of GMA (glycidyl methacrylate) was added to the pre-liquid, and the mixture was stirred at a constant temperature of 60° C. for 24 hours to obtain a solution after reaction; an appropriate amount of ethanol was added to the solution after reaction for precipitation, and a white product was obtained by vacuum filtration, and the product was washed with ethanol for 2-3 times, and a white product of modified sodium alginate was obtained after freeze-drying, i.e., modified sodium alginate.

[0064] The infrared spectra of modified sodium alginate, unmodified sodium alginate and GMA (glycidyl methacrylate) are shown in Figure 2. Figure 1 shown.

[0065] Figure 1 There are three curves in the figure, which are the infrared spectra of modified sodium alginate, unmodified sodium alginate and GMA (glycidyl methacrylate). The arrows in the figure indicate the characteristic peaks of the double bonds of modified sodium alginate. Figure 1 It can be concluded that sodium alginate has been successfully modified and obtained a double bond structure.

[0066] Example 2: A modified sodium alginate cross-linked hydrogel electrolyte and a preparation method thereof

[0067] This embodiment provides a method for preparing a modified sodium alginate cross-linked hydrogel electrolyte, comprising the following steps:

[0068] S1, take 2g of monomer acrylamide and dissolve it in 20mL of deionized water, use 30mg of ammonium persulfate and 50mg

[0069] The modified sodium alginate prepared in Example 1 was used as an initiator and a cross-linking agent, respectively. After the solute was fully dissolved, 200 μL of acrylic acid was added to adjust the pH of the solution to be weakly acidic (pH 3-5 to prevent precipitation of zinc salt in an alkaline environment) to obtain a prepolymer solution.

[0070] S2. Degas the prepolymerized solution, add it into a sealed mold, and polymerize it at 60° C. for two hours to obtain a hydrogel (the thickness of the hydrogel is 1-2 mm).

[0071] S3. Prepare 2M ZnSO4 solution as electrolyte, soak the hydrogel prepared in step S2 in the electrolyte for 24 hours and then take it out, cut the hydrogel into discs with a diameter of 16 mm and a thickness of 1 mm, and use them as electrolyte (modified sodium alginate cross-linked hydrogel electrolyte) and separator of zinc ion battery.

[0072] The actual picture of the modified sodium alginate cross-linked hydrogel electrolyte prepared in Example 2 is as follows Figure 2 .

[0073] from Figure 2 It can be seen that the surface of the modified sodium alginate cross-linked hydrogel is smooth and flat, has good scalability, and has the potential for large-scale production.

[0074] Example 3: A modified sodium alginate cross-linked hydrogel electrolyte and a preparation method thereof

[0075] Compared with Example 2, the difference is that in Example 3, 30 mg of the modified sodium alginate prepared in Example 1 is added, that is, 1.5% of the content of monomer acrylamide, and the remaining steps are the same as in Example 2.

[0076] Example 4: A modified sodium alginate cross-linked hydrogel electrolyte and a preparation method thereof

[0077] Compared with Example 2, the difference is that in Example 3, 40 mg of the modified sodium alginate prepared in Example 1 is added, that is, 2% of the content of the monomer acrylamide, and the remaining steps are the same as in Example 2.

[0078] Example 5: A modified sodium alginate cross-linked hydrogel electrolyte and a preparation method thereof

[0079] Compared with Example 2, the difference is that in Example 3, 60 mg of the modified sodium alginate prepared in Example 1 is added, that is, 3% of the content of the monomer acrylamide, and the remaining steps are the same as in Example 2.

[0080] Example 6: A modified sodium alginate cross-linked hydrogel electrolyte and a preparation method thereof

[0081] The only difference between Example 6 and Example 2 is that the hydrogel is not cut into round pieces after treatment, but is cut into 8cm×10cm sheets, with zinc foil as the negative electrode and manganese dioxide electrode as the positive electrode, and connected to an electronic meter for flexible application testing.

[0082] Comparative Example 1

[0083] Compared with Example 2, the difference is that in Comparative Example 1, the modified sodium alginate prepared in Example 1 is replaced by MBAA (N, N-methylenebisacrylamide) to prepare MBAA cross-linked hydrogel, and the remaining steps are the same as in Example 2.

[0084] Test Example 1: Battery Electrochemical Test

[0085] 1. When assembling the battery, the zinc foil is used as both the positive electrode and the negative electrode of the battery, and the hydrogels soaked in the electrolyte of Example 2, Example 6 and Comparative Example 1 are used as electrolytes and separators to perform symmetrical battery electrochemical tests.

[0086] 2. When assembling a full battery, the manganese dioxide pole piece is used as the positive electrode, the zinc foil is used as the negative electrode, and the hydrogel soaked in the electrolyte of Example 2, Example 6 and Comparative Example 1 is used as the electrolyte and separator to carry out full battery electrochemical testing.

[0087] result:

[0088] The electrochemical impedance test of the symmetrical battery assembled with the hydrogel prepared in Example 2 is as follows: Figure 3 As shown. The test voltage is 0V and the test frequency range is 0.1-1000000. Figure 3 It can be seen that the interfacial impedance of the hydrogel is small and the contact resistance is also small.

[0089] The ionic conductivity calculation diagram of the hydrogel prepared in Example 2 is as follows: Figure 4 As shown, from Figure 4 It can be seen that the ionic conductivity of the modified sodium alginate cross-linked hydrogel is higher than that of the MBAA cross-linked hydrogel, indicating that the modified sodium alginate cross-linked hydrogel electrolyte has better ion transport capacity.

[0090] The symmetrical battery assembled with the hydrogel prepared in Example 2 was -2 Current density and 1mAh cm -2 The cycle performance diagram under surface capacity is as follows Figure 5 As shown. Figure 5 It can be seen that the modified sodium alginate cross-linked hydrogel battery can be stably cycled for more than 900 hours and has good cycle stability.

[0091] The assembled symmetric battery of MBAA cross-linked hydrogel prepared in Comparative Example 1 was -2 Current density and 1mAhcm -2 The cycle performance diagram under surface capacity is as follows Figure 6 As shown. Figure 6 It can be seen that the battery of MBAA cross-linked hydrogel does not have long cycle capability under the same conditions.

[0092] The symmetrical battery assembled with the hydrogel prepared in Example 2 was -2 Current density and 1mAh cm -2 The cycle performance diagram under surface capacity is as follows Figure 7 As shown. Figure 7 It can be seen that the modified sodium alginate cross-linked hydrogel battery can be stably cycled for more than 800 hours and also has good cycle stability at high current density.

[0093] like Figure 8 As shown in FIG. 2 , the rate performance diagram of a full battery assembled with the modified sodium alginate cross-linked hydrogel electrolyte prepared in Example 2 and manganese dioxide as the positive electrode at different current densities of 0.1c, 0.2c, 0.5c, 1c and 2c. Figure 8 It can be seen that the material is stable in cycling under various current density tests, indicating that the hydrogel zinc ion battery has stable rate performance.

[0094] like Fig. 9 As shown, the cycle performance diagram of a full battery assembled using the modified sodium alginate cross-linked hydrogel electrolyte prepared in Example 2 and manganese dioxide as the positive electrode at a current density of 0.5A g-1.

[0095] Fig. 9 There are two curves in the graph, curve No. 1 is the Coulomb efficiency curve, and curve No. 2 is the charge-discharge specific capacity curve. Fig. 9 It can be seen that the zinc ion battery containing modified sodium alginate can be stably cycled for 200 cycles, and the residual capacity reaches 60 mAh g -1 . It shows that the zinc ion battery with modified sodium alginate cross-linked hydrogel electrolyte has stable cycling performance.

[0096] The modified sodium alginate cross-linked hydrogel flexible battery prepared in Example 6 has the following application effects under different conditions: Fig.10 As shown. Fig.10 It can be seen that the flexible battery of the present invention can still function under different conditions such as stretching, twisting, and folding.

[0097] The schematic diagram of the modified sodium alginate prepared in Example 1 is as follows Fig.11 shown.

[0098] The assembled symmetric battery of MBAA cross-linked hydrogel prepared in Comparative Example 1 was -2 Current density and 1mAhcm -2 The cycle performance diagram under surface capacity is as follows Fig.12 As shown. Fig.12 It can be seen that the battery of MBAA cross-linked hydrogel does not have long cycle capability under the same conditions.

[0099] like Fig.13 As shown, the full battery assembled with MBAA cross-linked hydrogel electrolyte prepared in Comparative Example 1 and manganese dioxide as the positive electrode was -1 Cycling performance diagram at current density of . Fig.13 There are two curves in the graph, curve No. 1 is the Coulomb efficiency curve, and curve No. 2 is the charge-discharge specific capacity curve. Fig.13 It can be seen that the capacity retention rate of the zinc ion battery of MBAA cross-linked hydrogel is poor.

[0100] Test Example 2: Swelling Rate Test

[0101] The modified sodium alginate cross-linked hydrogel prepared in Examples 2 to 5 was subjected to a swelling rate test. The initial average mass m0 of the hydrogel was weighed, and the mass was weighed every 24 hours and the average value m was taken for a swelling rate test to verify whether the modified sodium alginate can be used as a cross-linking agent and the absorption rate of the hydrogel to the electrolyte.

[0102] like Fig.14 As shown, the swelling rate curves of the modified sodium alginate cross-linked hydrogels of different concentrations prepared in Examples 2 to 5 and the control hydrogel (Comparative Example 1).

[0103] from Figure 14 to Figure 16 It can be seen that the swelling rate of the modified sodium alginate cross-linked hydrogel is better. With the increase of concentration, the degree of cross-linking increases and the swelling rate gradually decreases. This proves that the modified sodium alginate does act as a cross-linking agent. Figure 14 to Figure 16 It can be seen that 50 mg of modified sodium alginate is the optimal amount (Example 2).

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A method for preparing a modified sodium alginate cross-linked hydrogel electrolyte, characterized in that: The following steps are involved: S1, dissolving acrylamide monomer in deionized water, and then adding ammonium persulfate and modified sodium alginate to obtain a mixed solution; S2, adjusting the pH of the mixed solution obtained in step S1 to obtain a prepolymerization solution; S3, degassing the prepolymerized solution, sealing it, and polymerizing it to obtain a hydrogel; S4, immersing the hydrogel in an electrolyte to obtain a modified sodium alginate cross-linked hydrogel electrolyte; The double bond structure of glycidyl methacrylate is grafted onto sodium alginate to form modified sodium alginate.

2. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 1, characterized in that: The preparation method of the modified sodium alginate comprises the following steps: 1) dissolving sodium alginate in deionized water to obtain a pre-liquid, and adjusting the pH of the pre-liquid to be alkaline to obtain a mixed solution; 2) Glycidyl methacrylate is added to the mixed solution, mixed and stirred, and then precipitated, and then vacuum filtered, washed and freeze-dried to obtain modified sodium alginate.

3. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 2, characterized in that: The ratio of sodium alginate to glycidyl methacrylate is 4 g:0.675 μL.

4. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 2, characterized in that: The reagent for adjusting the pH of the pre-liquid includes NaOH, and the pH of the pre-liquid is 10-11.

5. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 1, characterized in that: The mass ratio of the ammonium persulfate to the modified sodium alginate is 1:(1-2).

6. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 5, characterized in that: The mass ratio of the ammonium persulfate to the modified sodium alginate is 3:

5.

7. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 1, characterized in that: In the step S2, the reagent for adjusting the pH of the mixed solution obtained in the step S1 includes acrylic acid.

8. The method for preparing the modified sodium alginate cross-linked hydrogel electrolyte according to claim 1, characterized in that: In the step S4, the electrolyte includes ZnSO4. 9 . The modified sodium alginate cross-linked hydrogel electrolyte prepared by the method for preparing a modified sodium alginate cross-linked hydrogel electrolyte according to claim 1 .

10. Use of the modified sodium alginate cross-linked hydrogel electrolyte according to claim 9 in preparing a battery.

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