A method for preparing a double network hydrogel electrolyte containing a complex zinc salt

Abstract

This invention provides a method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt, characterized by the following steps: S100: dissolving a composite zinc salt in an aqueous solution at a predetermined mass ratio to prepare a composite zinc salt electrolyte; S200: dissolving two water-soluble polymer precursors in an appropriate amount of aqueous solution at a predetermined mass ratio until completely dissolved to prepare a water-soluble polymer precursor solution; S300: adding the composite zinc salt electrolyte to the water-soluble polymer precursor solution at a predetermined mass ratio; S400: after the mixture is clarified, adding an initiator, stirring evenly, pouring into a glass mold, and settling at a constant temperature for a predetermined time to form a dual-network hydrogel electrolyte containing a composite zinc salt; A dual-network hydrogel electrolyte containing a composite zinc salt can be prepared using simple operation methods, preferentially forming a solid electrolyte interface rich in Li2O during charge-discharge cycles, inhibiting the growth of zinc dendrites.

Description

Technical Field

[0001] This invention relates to the technical field of new energy material preparation, specifically to a method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt. Background Technology

[0002] Double-network hydrogel electrolytes containing composite zinc salts are important quasi-solid-state electrolyte raw materials for energy storage devices, mainly used in the preparation of zinc-ion batteries and zinc-ion hybrid capacitors.

[0003] Currently, most dual-network hydrogel electrolytes containing complex zinc salts face a trade-off between mechanical strength and electrochemical performance; that is, it is difficult to retain their expected electrochemical properties while improving mechanical strength. This is because increasing the mechanical strength of the gel material requires enhanced polymer network cross-linking and denser intermolecular bonding, which restricts ion transport within the system and reduces electrochemical performance. The toughness of existing hydrogel electrolytes is typically below 150 kJ / m. 3 The stress is typically below 80 kPa, and when toughness and stress are increased, ideal electrochemical properties cannot be achieved. Therefore, designing high-strength, high-toughness ionogels with ideal electrochemical properties is currently the main challenge.

[0004] For example, patent applications with publication numbers CN120581380A, CN120237304A, CN119431661A, CN119297439A, and CN117133554A all disclose ion gel electrolytes prepared from zinc salts, their preparation methods, and their applications. In these zinc ion gel electrolytes, the polymer monomers are acrylamide, xanthan gum, or chitosan networks, which can improve mechanical strength and chemical stability. However, the electrochemical performance of the gel electrolytes is poor, especially the conductivity, which is below 50 mS / cm. Zinc-ion batteries assembled from these hydrogel electrolytes generally have a charge-discharge cycle count of less than 3000 times, and the overall performance of the batteries is difficult to meet the requirements of practical use.

[0005] Lithium salts are mostly ionic crystals with small ionic radii, high reactivity, and strong polarization. They have a strong hydration capacity; almost all lithium salts are hydrated, effectively altering the solvation environment. When used as an additive in conjunction with zinc salts, they enhance the film-forming ability of the anode interface and the stability of the cathode side against high-voltage solvent molecule oxidation, improve the compatibility between the electrolyte and active materials, and extend the charge-discharge cycle performance of zinc-ion batteries. Simultaneously, lithium salt additives can form new interface layers, passivate the cathode interface, inhibit zinc dendrite formation, prevent electrolyte oxidative decomposition, and especially prevent hydrogen evolution reaction, thus avoiding problems such as battery bulging and explosion.

[0006] Currently, there are few reports on the preparation of composite ionogels by simultaneously introducing lithium salt additives and dual-network polymers into gels. Therefore, developing composite ionogels with high strength, excellent toughness, simple preparation, and excellent electrochemical performance has become the key to expanding the application of flexible dual-network hydrogel electrolytes containing composite zinc salts. Summary of the Invention

[0007] To address the shortcomings and deficiencies of the existing technology, this invention provides a method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a dual-network hydrogel electrolyte containing a complex zinc salt, characterized by comprising the following steps: S100: Dissolve the composite zinc salt in an aqueous solution at a predetermined mass ratio to prepare the composite zinc salt electrolyte; S200: Dissolve two water-soluble polymer precursors in an appropriate amount of aqueous solution according to a preset mass ratio until they are completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add the composite zinc salt electrolyte to the water-soluble polymer precursor solution according to the preset mass ratio; S400: After the mixture is clarified, add the initiator, stir evenly, pour into a glass mold, and precipitate at a constant temperature for a preset time to form a double-network hydrogel electrolyte containing complex zinc salt.

[0009] As a further preferred embodiment of the present invention, in step S100, the composite zinc salt is obtained by mixing lithium salt and zinc salt in a certain mass ratio; wherein, the lithium salt is selected from any one of lithium chloride, lithium bromide, lithium sulfate, lithium fluoride, lithium phosphate, lithium perchlorate, lithium nitrate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluorosulfonyl)imide, or lithium trifluorosulfonylimide; and the zinc salt is selected from any one of zinc chloride, zinc sulfate, or zinc nitrate.

[0010] As a further preferred embodiment of the present invention, in step S100, the mass ratio of the lithium salt to the zinc salt is 1:10−1:20.

[0011] As a further preferred embodiment of the present invention, in step S200, the two water-soluble polymer precursors are composed of a first water-soluble polymer precursor and a second water-soluble polymer precursor in a preset mass ratio; wherein, the first water-soluble polymer precursor is selected from any one of acrylic acid, acrylamide, vinyl alcohol, ethylene glycol or vinylpyrrolidone; and the second water-soluble polymer precursor is selected from any one of carboxymethyl starch, starch acetate, hydroxymethyl cellulose, carboxymethyl cellulose, natural starch, plant gum, chitin, alginic acid, sodium alginate, gum arabic, xanthan gum or agar.

[0012] As a further preferred embodiment of the present invention, the preset mass ratio of the first water-soluble polymer precursor to the second water-soluble polymer precursor in step S200 is 5:1-10:1.

[0013] As a further preferred embodiment of the present invention, in step S300, the preset mass ratio of the composite zinc salt electrolyte to the water-soluble polymer precursor solution is 1:5-1:10.

[0014] As a further preferred embodiment of the present invention, in step S400, the initiator is selected from any one of persulfate, azobisisobutyramidine hydrochloride, azobisisobutyramidazole hydrochloride, azobisisobutyramidazole or azobiscyanopentanoic acid initiator.

[0015] As a further preferred embodiment of the present invention, in step S400, the constant temperature range is 50-70℃.

[0016] As a further preferred embodiment of the present invention, in step S400, the preset time for the isothermal precipitation is 4-8 hours.

[0017] Compared with the prior art, the advantages and positive effects of the present invention include: 1) This invention provides a method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt. Using a composite zinc salt and two water-soluble polymer precursors as raw materials, a dual-network hydrogel electrolyte containing a composite zinc salt can be prepared through a simple operation. This method breaks the binding of water on zinc ions and reconstructs the solvation environment of zinc ions, allowing zinc ions not encapsulated by the solvent to have more opportunities to interact with electron-rich groups on the polymer chain and conduct rapidly in the ion channels in the polymer. During charge-discharge cycles, a solid electrolyte interface rich in Li2O is preferentially formed, inhibiting the growth of zinc dendrites. This provides a simple method for designing flexible and highly conductive dual-network hydrogel electrolytes containing composite zinc salts. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. [First Embodiment] A dual-network hydrogel electrolyte containing a composite zinc salt was prepared by the following steps: S100: Dissolve 190.5 mg of lithium chloride and 2857.5 mg of zinc chloride in an aqueous solution to prepare an electrolyte containing a composite zinc salt; S200: Dissolve 6521.6 mg of acrylic acid and 931.7 mg of hydroxymethyl cellulose in an appropriate amount of aqueous solution until completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add 950.3 mg of composite zinc salt electrolyte to 7127.25 mg of water-soluble polymer precursor solution; S400: After the mixture in step S300 has clarified, add the initiator persulfate, stir evenly, pour into a glass mold, and precipitate at 60°C for 6 hours to form a double-network hydrogel electrolyte containing composite zinc salt.

[0019] The properties of the prepared electrolyte meet the following requirements: stress: 125.8 kPa; toughness: 225.4 kJ / m. 3 Electrical conductivity: 70.5 mS / cm. [Second Embodiment] A dual-network hydrogel electrolyte containing a composite zinc salt was prepared by the following steps: S100: Dissolve 150.8 mg of lithium chloride and 1508.1 mg of zinc chloride in an aqueous solution to prepare an electrolyte containing a composite zinc salt; S200: Dissolve 6325.4 mg of acrylic acid and 1265.08 mg of hydroxymethyl cellulose in an appropriate amount of aqueous solution until completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add 853.1 mg of composite zinc salt electrolyte to 4265.5 mg of water-soluble polymer precursor solution; S400: After the mixture in step S300 has clarified, add the initiator persulfate, stir evenly, pour into a glass mold, and precipitate at 50°C for 4 hours to form a double-network hydrogel electrolyte containing composite zinc salt.

[0020] The properties of the prepared electrolyte meet the following requirements: stress: 108.5 kPa; toughness: 217.7 kJ / m. 3 Electrical conductivity: 68.6 mS / cm. [Third Embodiment] A dual-network hydrogel electrolyte containing a composite zinc salt was prepared by the following steps: S100: Dissolve 135.2 mg of lithium chloride and 2704 mg of zinc chloride in an aqueous solution to prepare an electrolyte containing a composite zinc salt; S200: Dissolve 7506.8 mg of acrylic acid and 750.7 mg of hydroxymethyl cellulose in an appropriate amount of aqueous solution until completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add 539.2 mg of composite zinc salt electrolyte to 5392.0 mg of water-soluble polymer precursor solution; S400: After the mixture in step S300 has clarified, add the initiator persulfate, stir evenly, pour into a self-made glass mold, and precipitate at 70°C for 8 hours to form a double-network hydrogel electrolyte containing complex zinc salt.

[0021] The properties of the prepared electrolyte meet the following requirements: stress: 102.5 kPa; toughness: 211.4 kJ / m. 3 Electrical conductivity: 67.3 mS / cm. [Fourth Embodiment] A dual-network hydrogel electrolyte containing a composite zinc salt was prepared by the following steps: S100: Dissolve 151.2 mg of lithium perchlorate and 2265.0 mg of zinc sulfate in an aqueous solution to prepare an electrolyte containing a composite zinc salt; S200: Dissolve 8125.0 mg acrylamide and 1160.7 mg chitin in an appropriate amount of aqueous solution until completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add 460.5 mg of composite zinc salt electrolyte to 3453.8 mg of water-soluble polymer precursor solution; S400: After the mixture in step S300 has clarified, add the initiator persulfate, stir evenly, pour into a glass mold, and precipitate at 60°C for 6 hours to form a double-network hydrogel electrolyte containing composite zinc salt.

[0022] The properties of the prepared electrolyte meet the following requirements: stress: 109.2 kPa; toughness: 215.5 kJ / m. 3 Electrical conductivity: 65.8 mS / cm. [Fifth Embodiment] A dual-network hydrogel electrolyte containing a composite zinc salt was prepared by the following steps: S100: 210.2 mg lithium fluoride and 3153.1 mg zinc nitrate were dissolved in an aqueous solution to prepare an electrolyte containing a composite zinc salt; S200: Dissolve 6653.5 mg of vinyl alcohol and 950.5 mg of sodium alginate in an appropriate amount of aqueous solution until completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add 360.5 mg of composite zinc salt electrolyte to 2703.7 mg of water-soluble polymer precursor solution; S400: After the mixture in step S300 has clarified, add the initiator persulfate, stir evenly, pour into a glass mold, and precipitate at 60°C for 6 hours to form a double-network hydrogel electrolyte containing composite zinc salt.

[0023] The properties of the prepared electrolyte meet the following requirements: stress: 103.7 kPa; toughness: 208.6 kJ / m. 3 Electrical conductivity: 66.4 mS / cm.

[0024] Table 1. Performance Comparison of Existing Products and Hydrogel Electrolytes Obtained in Each Example Toughness, kJ / m 3 ]]> Stress, kPa Conductivity, mS / cm Charge-discharge cycle number, times Prior art product ＜150 ＜80 50 ＜3000 First embodiment 225.4 125.8 70.5 ＞5000 Second embodiment 217.7 108.5 68.6 ＞5000 Third embodiment 211.4 102.5 67.3 ＞5000 Fourth embodiment 215.5 109.2 65.8 ＞5000 Fifth embodiment 208.6 103.7 66.4 ＞5000 As can be seen from Table 1 above, the performance of the hydrogel electrolytes prepared through the various embodiments of the present invention meets the following requirements: 1) The addition of lithium salt to the composite zinc salt forms a Li₂O-rich solid electrolyte interface at the electrode, inhibiting the growth of zinc dendrites on the electrode during charge and discharge of the zinc-ion battery. Electrochemical workstation measurements show that the battery charge-discharge cycle life can be effectively increased to over 5000 cycles.

[0025] 2) Due to the addition of two water-soluble polymer precursors, the prepared dual-network hydrogel electrolyte is rich in hydroxyl and carboxyl groups, which reconstructs the solvation structure of zinc ions, enhances the transport capacity of zinc ions in the system, and effectively improves the conductivity of the hydrogel electrolyte, so that the conductivity of the prepared dual-network hydrogel electrolyte can be stably maintained above 50 mS / cm.

[0026] 3) Due to the addition of two water-soluble polymer precursors, a superior network structure is formed, resulting in hydrogel electrolytes with higher conductivity, stress, and toughness compared to other formulations. This significantly improves the stress and toughness of the prepared dual-network hydrogel, allowing its stress to be stably maintained above 80 kPa and its toughness to be stably maintained at 150 kJ / m. 3 above.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt, characterized in that: Includes the following steps: S100: Dissolve the composite zinc salt in an aqueous solution at a predetermined mass ratio to prepare the composite zinc salt electrolyte; S200: Dissolve two water-soluble polymer precursors in an appropriate amount of aqueous solution according to a preset mass ratio until they are completely dissolved to prepare a water-soluble polymer precursor solution; S300: Add the composite zinc salt electrolyte to the water-soluble polymer precursor solution according to the preset mass ratio; S400: After the mixture is clarified, add the initiator, stir evenly, pour into a glass mold, and precipitate at a constant temperature for a preset time to form a double-network hydrogel electrolyte containing complex zinc salt.

2. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 1, characterized in that: In step S100, the composite zinc salt is obtained by mixing lithium salt and zinc salt in a certain mass ratio; wherein, the lithium salt is selected from any one of lithium chloride, lithium bromide, lithium sulfate, lithium fluoride, lithium phosphate, lithium perchlorate, lithium nitrate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluorosulfonyl)imide, or lithium trifluorosulfonylimide; and the zinc salt is selected from any one of zinc chloride, zinc sulfate, or zinc nitrate.

3. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 2, characterized in that: In step S100, the mass ratio of lithium salt to zinc salt is 1:10−1:

20.

4. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 1, characterized in that: In step S200, the two water-soluble polymer precursors are composed of a first water-soluble polymer precursor and a second water-soluble polymer precursor in a preset mass ratio; wherein, the first water-soluble polymer precursor is selected from any one of acrylic acid, acrylamide, vinyl alcohol, ethylene glycol or vinylpyrrolidone; and the second water-soluble polymer precursor is selected from any one of carboxymethyl starch, acetic acid starch, hydroxymethyl cellulose, carboxymethyl cellulose, natural starch, plant gum, chitin, alginic acid, sodium alginate, gum arabic, xanthan gum or agar.

5. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 4, characterized in that: In step S200, the preset mass ratio of the first water-soluble polymer precursor to the second water-soluble polymer precursor is 5:1-10:

1.

6. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 1, characterized in that: In step S300, the preset mass ratio of the composite zinc salt electrolyte to the water-soluble polymer precursor solution is 1:5-1:

10.

7. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 1, characterized in that: In step S400, the initiator is selected from any one of persulfate, azobisisobutyramidine hydrochloride, azobisisobutyramidine hydrochloride, azobisisobutyramidine, or azobiscyanopentanoic acid initiator.

8. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 1, characterized in that: In step S400, the constant temperature range is 50-70℃.

9. The method for preparing a dual-network hydrogel electrolyte containing a composite zinc salt according to claim 1, characterized in that: In step S400, the preset time for the isothermal precipitation is 4-8 hours.