Preparation method of a highly viscous polyvinyl pyrrolidone-based gel electrolyte and its application in aqueous zinc-iodine batteries

Abstract

This invention discloses a method for preparing a highly viscous polyvinylpyrrolidone (PVP)-based gel electrolyte and its application in aqueous zinc-iodine batteries, belonging to the field of battery technology. The method includes mixing vinylpyrrolidone with monomers, adding solvent and stirring thoroughly, then adding a crosslinking agent and an initiator to perform a copolymerization reaction to obtain a PPVP-based copolymer; mixing the PPVP-based copolymer with biomass sugars, pouring it into a mold and heating it to obtain a composite film; and immersing the composite film in a zinc salt solution to obtain the highly viscous PPVP-based gel electrolyte. This method can prepare a highly viscous PPVP-based gel electrolyte with strong adhesion and mechanical strength, while also possessing advantages such as being environmentally friendly and low-cost. This highly viscous PPVP-based gel electrolyte can be used in the preparation of aqueous zinc-iodine batteries.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte and its application in aqueous zinc-iodine batteries. Background Technology

[0002] Electrochemical energy storage technology, as a core support for the development of new energy sources, can effectively solve the problems of randomness, intermittency, volatility, and dispersion of green new energy sources such as solar, wind, geothermal, and tidal energy. It is of great significance for realizing the large-scale production and application of new energy power sources. The rechargeable aqueous zinc-iodine battery is a novel secondary battery system that primarily achieves energy storage and release through the "solid-liquid conversion" of active materials, namely Zn... 2+ Zn (-0.76V vs. SHE, 820mAh g) -1 ) and I2 I - (0.54V vs. SHE, 211mAh g) -1 This mechanism features rapid reaction kinetics, and the introduction of a high-ionic-conductivity aqueous electrolyte not only further enhances the electrochemical kinetics of the system but also ensures its safety. Furthermore, the high abundance and low cost of the active materials zinc and iodine make zinc-iodine batteries easy to mass-produce. However, the practical application of aqueous zinc-iodine secondary batteries is currently limited by two main factors: 1. Zinc anode dendrites and side reactions lead to short circuits and reduced coulombic efficiency; 2. The shuttle effect of polyiodide ions in the iodine cathode significantly affects the long-cycle performance of the battery.

[0003] To address the above issues, researchers have conducted extensive studies, but most have focused on suppressing the shuttle effect of polyiodide ions in the iodine cathode, with limited effects on regulating zinc anode deposition. For example, CN107666015A discloses a zinc-iodine secondary battery with an aqueous electrolyte system and its preparation method. This patent uses ordinary carbon materials for the cathode to suppress the formation of polyiodides, and only polishes the anode electrode. CN117430824A discloses a nitrogen-doped hollow MOF material, its preparation method, and its application. This patent does not optimize or modify the zinc anode. CN115693022A discloses a zinc-iodine battery separator based on a covalent organic framework, its preparation method, and its application, which also have limited effects on improving the uniformity of zinc ion deposition and suppressing side reactions in the zinc anode. Summary of the Invention

[0004] In view of this, the present invention proposes a method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte and its application in an aqueous zinc-iodine battery.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One objective of this invention is to provide a method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte, comprising the following steps:

[0007] Vinylpyrrolidone was mixed with monomers, solvent was added and stirred thoroughly, and then crosslinking agent and initiator were added to carry out copolymerization reaction to obtain polyvinylpyrrolidone-based copolymer;

[0008] The polyvinylpyrrolidone copolymer is mixed with biomass sugars, poured into a mold and heated to obtain a composite film.

[0009] The composite membrane is immersed in a zinc salt solution to obtain a highly viscous polyvinylpyrrolidone-based gel electrolyte.

[0010] This invention prepares a polyvinylpyrrolidone-based copolymer using vinylpyrrolidone and monomers as raw materials, which improves the stability of polyvinylpyrrolidone in aqueous solution and enhances the mechanical strength of the electrolyte. Biomass sugars contain numerous polar functional groups, such as hydroxyl, carboxyl, ether, and amino groups, which can impart stronger adhesiveness to polyvinylpyrrolidone-based gel electrolytes. Furthermore, biomass sugars are natural polysaccharides extracted from natural organisms, offering advantages such as being green, low-cost, and biodegradable.

[0011] Further, the monomer includes one or more of styrene, vinyl chloride, vinyl alcohol, vinyl acetate, ethoxyethylene, ethylene glycol vinyl ether, cyclohexyl vinyl ether, 2-vinylpyridine, ethylene ethylene carbonate, acrylamide, acrylic acid, methyl methacrylate, ethyl acrylate, acrylonitrile, and maleic acid.

[0012] Further, the crosslinking agent is one or more selected from N,N'-methyleneacrylamide, N,N'-methylenebisacrylamide, epichlorohydrin, dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, diisocyanate, divinyl propylbenzene, and diisocyanate.

[0013] Further, the initiator is one or more selected from potassium persulfate, sodium perbromate, benzoyl peroxide, ammonium persulfate, lauroyl peroxide, azobis(dimethyl)valerate, sodium azobis(cyanovate), benzoyl, azobis(isopropyl)imidazoline hydrochloride, azobis(cyanovate) acid, azobis(isobutyronitrile) and azobis(isobutyramidine) hydrochloride.

[0014] Furthermore, the biomass sugars include one or more of sodium alginate, sodium carboxymethyl cellulose, cellulose, chitosan, gum arabic, guar gum, starch, xanthan gum, agar, peach gum, and cyclodextrin.

[0015] Further, the zinc salt concentration is 0.05-10 mol / L, including one or more of zinc sulfate, zinc chloride, zinc perchlorate, zinc trifluoromethanesulfonate, zinc acetate, zinc tetrafluoroborate, and zinc bis(trifluoromethanesulfonyl)imide.

[0016] Further, the molar ratio of the vinylpyrrolidone to the monomer is (0.1-10):1; and / or

[0017] The amount of the crosslinking agent added is 0.1-1% of the mass of the monomer; and / or

[0018] The amount of the initiator added is 0.1-1% of the mass of the monomer; and / or

[0019] The conditions for the copolymerization reaction are: temperature 20-100℃, time 1-48h; and / or

[0020] The mass ratio of the polyvinylpyrrolidone copolymer to the biomass sugar is (0.1-10):1; and / or

[0021] The heat treatment conditions are: temperature 80℃, time 2h; and / or

[0022] The soaking time is 1-48 hours.

[0023] The second objective of this invention is to provide a highly viscous polyvinylpyrrolidone-based gel electrolyte, which is obtained using the above-described preparation method.

[0024] A third objective of this invention is to provide an aqueous zinc-iodine battery, comprising the aforementioned highly viscous polyvinylpyrrolidone-based gel electrolyte.

[0025] Because polyvinylpyrrolidone (PVP) can form charge-transfer complexes with polyiodide ions, it can effectively suppress the shuttle effect of polyiodide ions at the positive electrode. The low number of water molecules in the gel electrolyte also suppresses the shuttle effect. The strong adhesion of the gel electrolyte improves the interfacial stability between the electrolyte and the positive electrode, which is beneficial for zinc ion shuttle and improves battery performance. Simultaneously, the low number of water molecules in the gel electrolyte also suppresses water-related side reactions at the zinc negative electrode. The strong adhesion of the gel electrolyte improves the interfacial stability between the electrolyte and the zinc negative electrode, which is beneficial for zinc ion shuttle and improves battery performance. The gel electrolyte can increase the zinc ion deposition overpotential, regulate the zinc ion flux, suppress two-dimensional diffusion of zinc ions, and improve the uniformity of zinc ion deposition at the negative electrode. In other words, the PPVP-based gel electrolyte prepared in this invention can not only suppress the shuttle effect of polyiodide ions at the positive electrode by forming charge-transfer complexes and reducing the number of water molecules, but also improve the stability between the electrolyte and the positive electrode through the strong adhesion of the electrolyte. The prepared polyvinylpyrrolidone-based gel electrolyte can not only suppress the side reactions of the zinc anode by reducing the number of water molecules and improve the stability between the electrolyte and the anode through the strong adhesion of the electrolyte, but also increase the zinc ion deposition overpotential through the polymer, regulate the zinc ion flux, suppress the two-dimensional diffusion of zinc ions, and improve the uniformity of zinc ion deposition on the anode.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] This invention provides a method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte, and applies the prepared gel electrolyte to an aqueous zinc-iodine battery. Its advantages include: 1) The preparation method provided by this invention can obtain a polyvinylpyrrolidone-based gel electrolyte with high mechanical strength, strong adhesion, environmental friendliness, and low cost; 2) The polyvinylpyrrolidone-based gel electrolyte prepared by this invention can not only suppress the shuttle effect of polyiodide ions at the positive electrode, but also improve the stability between the electrolyte and the positive electrode; 3) The polyvinylpyrrolidone-based gel electrolyte prepared by this invention can not only suppress the side reactions of the zinc negative electrode and improve the stability between the electrolyte and the negative electrode, but also improve the uniformity of zinc ion deposition at the negative electrode. Attached Figure Description

[0028] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 A photograph of the highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1;

[0030] Figure 2The tensile strain curve of the highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1 is shown.

[0031] Figure 3 This is a 180º peel test image of the highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1.

[0032] Figure 4 SEM image of zinc foil after 10 cycles of the symmetrical battery in Application Example 1;

[0033] Figure 5 The graph shows the long-cycle performance of the symmetrical battery in Application Example 2;

[0034] Figure 6 The second charge-discharge curve of the aqueous zinc-iodine button cell in Application Example 3;

[0035] Figure 7 A schematic diagram illustrating the long-cycle performance of the aqueous zinc-iodine button cell in Application Example 3;

[0036] Figure 8 A schematic diagram of the long-cycle performance of the aqueous zinc-iodine button cell in Comparative Example 1.

[0037] Figure 9 This is a schematic diagram of the long-cycle performance of the aqueous zinc-iodine button cell in Comparative Example 2. Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0042] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0043] This invention provides a method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte, comprising the following steps:

[0044] 1) Mix vinylpyrrolidone with monomers, add solvent and stir thoroughly, then add crosslinking agent and initiator to carry out copolymerization reaction to obtain polyvinylpyrrolidone-based copolymer; the solvent can be water;

[0045] 2) The polyvinylpyrrolidone copolymer is mixed with biomass sugars, poured into a mold and heated to obtain a composite film;

[0046] 3) Immerse the composite membrane in a zinc salt solution to obtain a highly viscous polyvinylpyrrolidone gel electrolyte.

[0047] In some embodiments of the present invention, the monomer includes one or more of styrene, vinyl chloride, vinyl alcohol, vinyl acetate, ethoxyethylene, ethylene glycol vinyl ether, cyclohexyl vinyl ether, 2-vinylpyridine, ethylene ethylene carbonate, acrylamide, acrylic acid, methyl methacrylate, ethyl acrylate, acrylonitrile, and maleic acid. Exemplarily, in the following embodiments of the present invention, the monomer may be selected from acrylamide or acrylic acid.

[0048] In some embodiments of the present invention, the crosslinking agent is one or more selected from N,N'-methyleneacrylamide, N,N'-methylenebisacrylamide, epichlorohydrin, dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, diisocyanate, divinyl propylbenzene, and diisocyanate. Exemplarily, in the following embodiments of the present invention, the crosslinking agent may be selected from N,N'-methyleneacrylamide or epichlorohydrin.

[0049] In some embodiments of the present invention, the initiator is one or more selected from potassium persulfate, sodium perbromate, benzoyl peroxide, ammonium persulfate, lauroyl peroxide, azobis(dimethyl)valerate, sodium azobis(cyanovate), benzoyl, azobisisopropylimidazoline hydrochloride, azobis(cyanovate) acid, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride. Exemplarily, in the following embodiments of the present invention, the initiator may be selected from azobisisobutyronitrile or ammonium persulfate.

[0050] In some embodiments of the present invention, the biomass sugars include one or more of sodium alginate, sodium carboxymethyl cellulose, cellulose, chitosan, gum arabic, guar gum, starch, xanthan gum, agar, peach gum, and cyclodextrin. Exemplarily, in the following embodiments of the present invention, the biomass sugars may be selected from sodium alginate or chitosan.

[0051] In some embodiments of the present invention, the zinc salt includes one or more of zinc sulfate, zinc chloride, zinc perchlorate, zinc trifluoromethanesulfonate, zinc acetate, zinc tetrafluoroborate, and zinc bis(trifluoromethanesulfonyl)imide. Exemplarily, in the following embodiments of the present invention, the zinc salt may be selected from zinc sulfate or zinc perchlorate. The concentration of the zinc salt is 0.05-10 mol / L. Exemplarily, in the following embodiments of the present invention, an effect verification is performed using a zinc salt concentration of 2 mol / L as an example.

[0052] In some embodiments of the present invention, the molar ratio of vinylpyrrolidone to monomer is (0.1-10):1. For example, in the following embodiments of the present invention, the molar ratio of vinylpyrrolidone to monomer is 0.7:1.

[0053] In some embodiments of the present invention, the amount of crosslinking agent added is 0.1-1% of the monomer mass. For example, in the following embodiments of the present invention, the amount of crosslinking agent added is 0.14% of the monomer mass.

[0054] In some embodiments of the present invention, the amount of the initiator added is 0.1-1% of the monomer mass. For example, in the following embodiments of the present invention, the amount of the initiator added is 0.47% of the monomer mass.

[0055] In the following embodiments of the present invention, the conditions for the copolymerization reaction are: temperature 50°C and time 20h.

[0056] In some embodiments of the present invention, the mass ratio of the polyvinylpyrrolidone copolymer to the biomass sugar is (0.1-10):1. For example, in the following embodiments of the present invention, the mass ratio of the polyvinylpyrrolidone copolymer to the biomass sugar is 1:1.

[0057] In the following embodiments of the present invention, the conditions for the heat treatment are: temperature 80°C, time 2 hours.

[0058] In the following embodiments of the present invention, the soaking time is 1-48 hours. For example, in the following embodiments of the present invention, a soaking time of 24 hours is used as an example to verify the effect.

[0059] A highly viscous polyvinylpyrrolidone-based gel electrolyte can be prepared using the above preparation method.

[0060] The prepared highly viscous polyvinylpyrrolidone-based gel electrolyte can be used to prepare aqueous zinc-iodine batteries.

[0061] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0062] All raw materials used in this invention were purchased from the market.

[0063] The technical solution of the present invention will be further illustrated by the following embodiments.

[0064] Example 1

[0065] A method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte includes the following steps:

[0066] (1) Mix 2.43g vinylpyrrolidone and 2.44g acrylamide (molar ratio of 0.7:1), add 2mL water, and stir thoroughly to obtain a mixed solution; add 0.64mg N,N'-methyleneacrylamide and 2.16mg azobisisobutyronitrile to the mixed solution, then pour the mixture into a glass mold and heat at 50℃ for 20h for copolymerization reaction, freeze dry to obtain a solid, grind into powder, and obtain polyvinylpyrrolidone-based copolymer powder;

[0067] (2) Take 0.1g of polyvinylpyrrolidone copolymer powder and 0.1g of sodium alginate, mix them and dissolve them in 100mL of water, stir for 2h, pour them into a mold and heat at 80℃ for 2h, demold to obtain a composite film;

[0068] (3) The composite membrane was soaked in a 2 mol / L zinc sulfate solution for 24 h to obtain a highly viscous polyvinylpyrrolidone gel electrolyte.

[0069] Figure 1 The image shows the physical sample of the highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1. As can be seen from the image, the gel electrolyte is transparent, and the lettering "CJLU" can be seen below.

[0070] Figure 2 The mechanical tensile test of the strong viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1 shows that the gel electrolyte can withstand a very strong tensile force without breaking. According to the tensile strain curve, the gel electrolyte can withstand a tensile rate of 685%, corresponding to a tensile force of 0.15 MPa, indicating that the gel electrolyte has high mechanical strength and strong toughness.

[0071] Figure 3The figure shows a 180º peel test of the strong adhesive polyvinylpyrrolidone-based gel electrolyte prepared in Example 1. As can be seen from the figure, the cross-section of the gel electrolyte is 20 mm, and the adhesive force it can withstand is about 2.9 N. Therefore, its adhesive strength is 145 N / m, indicating that the gel electrolyte has a very strong adhesive force.

[0072] Application Example 1

[0073] The highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1 was used to form a symmetrical battery with two circular zinc foils, each 14 mm in diameter and 0.01 mm thick. The battery was tested at a current of 1 mA cm⁻¹. -2 Surface capacity is 1mAh cm -2 The zinc foil was circulated for 10 cycles under the specified conditions, and then the circulated zinc foil was removed and the deposition morphology of the zinc foil was studied using SEM.

[0074] Figure 4 The image shows a SEM image of the zinc foil after 10 cycles of the symmetrical battery in Example 1. Figure 4 As can be seen, the surface of the zinc foil after cycling is smooth and clean, without the formation of zinc dendrites, proving that the electrolyte prepared in Example 1 of this invention can improve the uniformity of zinc ion deposition.

[0075] Application Example 2

[0076] The highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 1 was used to form a symmetrical battery with two circular zinc foils, each 14 mm in diameter and 0.01 mm thick. The battery was tested at a current of 1 mA cm⁻¹. -2 Surface capacity is 1mAh cm -2 Under these conditions, long-cycle testing was conducted.

[0077] Figure 5 The graph shows the long-cycle performance of the symmetrical battery in Application Example 2. As can be seen from the graph, the symmetrical battery did not exhibit a short circuit after 4000 cycles.

[0078] Example 2

[0079] A method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte includes the following steps:

[0080] (1) Mix 2.43g vinylpyrrolidone with 2.27g acrylic acid (molar ratio of the two is 0.7:1), add 2mL water, and stir thoroughly to obtain a mixed solution; add 0.64mg epichlorohydrin and 2.16mg ammonium persulfate to the mixed solution, then pour the whole mixture into a glass mold and heat at 50℃ for 20h for copolymerization reaction, freeze dry to obtain a solid, grind into powder, and obtain polyvinylpyrrolidone-based copolymer powder;

[0081] (2) Take 0.1g of polyvinylpyrrolidone copolymer powder and 0.1g of chitosan, mix them and dissolve them in 100mL of water, stir for 2h, pour into a mold and heat at 80℃ for 2h, demold to obtain composite film;

[0082] (3) The composite membrane was immersed in a 2 mol / L zinc perchlorate solution for 24 h to obtain a highly viscous polyvinylpyrrolidone gel electrolyte.

[0083] Application Example 3

[0084] The highly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 2 was used in an aqueous zinc-iodine battery. The specific steps are as follows:

[0085] (1) Mix 1g of iodine with 1g of activated carbon material in a sealed container, heat at 120°C for 2 hours, and cool to room temperature to obtain carbon-iodine composite material, which is used as positive electrode active material for zinc-iodine battery.

[0086] (2) 0.7g carbon-iodine composite, 0.15g carbon black conductive agent and 0.15g PVDF binder were stirred in N-methyl-2-pyrrolidone (NMP), ultrasonically dispersed to form a slurry, and uniformly coated on a 0.05mm thick titanium foil with a coating thickness of 150μm. After vacuum drying, it was cut into 12mm diameter round pieces as positive electrode plates.

[0087] (3) A circular zinc foil with a diameter of 14 mm and a thickness of 0.01 mm is used as the negative electrode sheet;

[0088] (4) The positive electrode, negative electrode, and the strongly viscous polyvinylpyrrolidone-based gel electrolyte prepared in Example 2 were assembled into an aqueous zinc-iodine coin cell. The battery was tested at 1 A g. -1 Cycling at current density, charge / discharge cutoff voltage is 0.6-1.6V vs. Zn. 2+ / Zn.

[0089] Figure 6 The second charge-discharge curve of the aqueous zinc-iodine coin cell in Example 3 shows a charge-discharge plateau typical of the active material iodine. From... Figure 6 As can be seen, the battery's average discharge voltage is approximately 1.2 V, and its discharge specific capacity is 127 mAh g. -1 The charging specific capacity is 126.5 mAh g. -1 The coulombic efficiency is 99.6%, indicating that the battery has good cycle reversibility.

[0090] Figure 7 This is a schematic diagram illustrating the long-cycle performance of the aqueous zinc-iodine coin cell in Example 3. The diagram shows that at 1 Ag... -1 The first discharge specific capacity is 130.6 mAh g.-1 (Based on the mass of the positive electrode active material), the coulombic efficiency in the first cycle is 96.8%, and the capacity retention rate after 2000 cycles is 88.1%, demonstrating good long-cycle performance. 1 A g -1 At the given current density, the full battery takes approximately 5 minutes to complete one charge-discharge cycle, demonstrating good reaction kinetics.

[0091] Comparative Example 1

[0092] Same as Example 2, except that no acrylic monomer is added for copolymerization.

[0093] Figure 8 This is a schematic diagram of the long-cycle performance of the aqueous zinc-iodine coin cell in Comparative Example 1. Similar to Application Example 3, the difference is that the gel electrolyte prepared in Comparative Example 1 was used. The results showed that at 1 A g… -1 The first discharge specific capacity is 120.9 mAhg. -1 (Based on the mass of the positive electrode active material), the coulombic efficiency was 95% in the first cycle. After 979 cycles, the coulombic efficiency dropped significantly, indicating a short circuit. The lack of copolymerization of other monomers significantly reduced the mechanical strength of the electrolyte, failing to suppress dendrite growth and leading to a short circuit.

[0094] Comparative Example 2

[0095] Same as Example 2, except that it is not mixed with chitosan.

[0096] Figure 9 This is a schematic diagram of the long-cycle performance of the aqueous zinc-iodine coin cell in Comparative Example 2. Similar to Application Example 3, the difference is that the gel electrolyte prepared in Comparative Example 2 was used. The results showed that at 1 A g… -1 The first discharge specific capacity is 121.7 mAh g. -1 (Based on the mass of the positive electrode active material), the coulombic efficiency in the first cycle is 95.3%, and after 2000 cycles, the discharge specific capacity is 68.6 mAh g. -1 The capacity retention rate was 56.4%. The lack of biomass sugars reduced the binding performance of the electrolyte, which was detrimental to the contact stability between the electrolyte and the electrode plates, resulting in a decrease in the cycle stability of the battery.

[0097] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a highly viscous polyvinylpyrrolidone-based gel electrolyte, characterized in that, Includes the following steps: Vinylpyrrolidone was mixed with monomers, solvent was added and stirred thoroughly, and then crosslinking agent and initiator were added to carry out copolymerization reaction to obtain polyvinylpyrrolidone-based copolymer; The polyvinylpyrrolidone copolymer is mixed with biomass sugars, poured into a mold, and heated to obtain a composite film; the heating temperature is 80°C. The composite membrane is immersed in a zinc salt solution to obtain a highly viscous polyvinylpyrrolidone-based gel electrolyte. The monomer is acrylamide or acrylic acid; The biomass sugars mentioned are sodium alginate or chitosan.

2. The method for preparing the highly viscous polyvinylpyrrolidone-based gel electrolyte according to claim 1, characterized in that, The crosslinking agent is one or more of N,N'-methyleneacrylamide, N,N'-methylenebisacrylamide, epichlorohydrin, dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, diisocyanate, divinyl propylbenzene, and diisocyanate.

3. The method for preparing the highly viscous polyvinylpyrrolidone-based gel electrolyte according to claim 1, characterized in that, The initiator is one or more of potassium persulfate, sodium perbromate, benzoyl peroxide, ammonium persulfate, lauroyl peroxide, azobis(dimethyl)valerate, sodium azobis(cyanovate), benzoyl, azobis(isopropyl)imidazoline hydrochloride, azobis(cyanovate) acid, azobis(isobutyronitrile) and azobis(isobutyramidine) hydrochloride.

4. The method for preparing the highly viscous polyvinylpyrrolidone-based gel electrolyte according to claim 1, characterized in that, The zinc salt concentration is 0.05-10 mol / L, including one or more of zinc sulfate, zinc chloride, zinc perchlorate, zinc trifluoromethanesulfonate, zinc acetate, zinc tetrafluoroborate, and zinc bis(trifluoromethanesulfonyl)imide.

5. The method for preparing the highly viscous polyvinylpyrrolidone-based gel electrolyte according to claim 1, characterized in that, The molar ratio of the vinylpyrrolidone to the monomer is (0.1-10):1; and / or The amount of the crosslinking agent added is 0.1-1% of the mass of the monomer; and / or The amount of the initiator added is 0.1-1% of the mass of the monomer; and / or The conditions for the copolymerization reaction are: temperature 20-100℃, time 1-48h; and / or The mass ratio of the polyvinylpyrrolidone copolymer to the biomass sugar is (0.1-10):1; and / or The soaking time is 1-48 hours.

6. A highly viscous polyvinylpyrrolidone-based gel electrolyte prepared by the preparation method according to any one of claims 1-5.

7. The application of the strong-viscosity polyvinylpyrrolidone-based gel electrolyte as described in claim 6 in an aqueous zinc-iodine battery.

Images