Aqueous zinc ion battery electrolyte containing fulvic acid additive as well as preparation method and application of aqueous zinc ion battery electrolyte

Abstract

The invention discloses an aqueous zinc ion battery electrolyte containing a fulvic acid additive and a preparation method and application thereof, the content of fulvic acid in the aqueous zinc ion electrolyte is 0.1 wt%-10wt%, and the aqueous zinc ion battery electrolyte containing the fulvic acid additive is suitable for an aqueous zinc ion battery. The invention also specifically discloses a preparation method of the aqueous zinc ion battery electrolyte containing the fulvic acid additive and application of the aqueous zinc ion battery electrolyte in preparation of an aqueous zinc ion battery. The fulvic acid additive is added into the electrolyte, so that a stable electrode-electrolyte interface is constructed under the synergistic effect of various strategies, a zinc deposition surface is smoother, disordered growth of zinc dendrites is inhibited, the electrochemical stability of the water-based zinc ion battery is improved, the cycle life of the water-based zinc ion battery is prolonged, and the electrochemical performance of the water-based zinc ion battery is prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-performance aqueous zinc-ion battery electrolyte, and particularly relates to an aqueous zinc-ion battery electrolyte containing a fulvic acid additive as well as a preparation method and application thereof. BACKGROUND

[0002] With the increasing demand for renewable energy, the importance of large-scale energy storage technology is also increasingly prominent. Aqueous zinc-ion batteries have become a promising energy storage solution due to their high safety, low cost, and large theoretical capacity. In aqueous zinc-ion batteries, zinc metal anodes provide a high theoretical volume capacity (820 mAh / g and 5855 mAh / cm³) and a low redox potential (-0.76 V vs. standard hydrogen electrode (SHE). In alkaline environments, zinc electrodes are passivated by insulating ZnO and Zn(OH)2 byproducts, and zinc dendrite growth is severe, causing irreversible batteries. In contrast, in neutral and weakly acidic aqueous electrolytes, the reversibility of zinc anodes is significantly enhanced, and the formation of alkaline byproducts is inhibited, while zinc dendrite growth is less. However, the zinc electrode interface in acidic electrolytes is accompanied by hydrogen evolution and electrolyte corrosion, which in turn causes uneven micro-electric fields, accelerating dendrite growth and byproduct generation during cycling. Dendrite growth, low plating / detaching efficiency of zinc anodes, corrosion, and side reactions significantly hinder the practical application of aqueous zinc-ion batteries.

[0003] To solve the above problems, researchers have used methods such as electrolyte optimization, electrode structure design, separator design and modification to suppress the side reactions of zinc anodes to improve the reversibility of zinc anodes. Among them, the electrolyte additive strategy is a simple and effective method. However, traditional additives often have single functions, making it difficult to simultaneously address multiple issues such as pH regulation, interface protection, and solvent optimization. Developing an integrated additive that can achieve interface pH stability, inhibit dendrite and hydrogen evolution reactions is crucial to breaking through the bottleneck of aqueous zinc-ion batteries.

[0004] The patent document CN2024117427169 discloses a lithium ion battery and a power device, specifically discloses that the lithium ion battery comprises a positive electrode sheet and an electrolyte, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer and / or the electrolyte comprises an additive, the additive comprises humic acid, the positive electrode film layer further comprises a positive electrode active material, and the positive electrode active material comprises manganese elements. The lithium ion battery provided by the patent adds humic acid in the positive electrode film layer and / or the electrolyte, the positive electrode active material of the positive electrode film layer comprises manganese elements, the complexing ability of the functional groups such as hydroxyl and carboxyl on the surface of humic acid to manganese ions is greater than that to lithium ions, therefore, humic acid preferentially reacts with manganese ions to fix manganese ions, thereby effectively preventing manganese ions from dissolving and migrating to the negative electrode side to damage the SEI film. The functional principle of humic acid in the patent document is to modify the positive electrode of the lithium ion battery, and humic acid realizes complexation reaction with manganese ions in an organic system.

[0005] The patent document CN201711495047X discloses a storage battery electrolyte and a preparation method thereof, specifically discloses that the raw material composition of the electrolyte comprises 0.2-0.75wt% of sodium lignosulfonate, 0.25-0.75wt% of humic acid, 1.5-2wt% of tetrabutylammonium bromide, 1.5-2wt% of polyoxyethylene sorbitan monolaurate, 0.05-0.25wt% of cobalt sulfate, 90-95wt% of sulfuric acid, and the rest is deionized water. The electrolyte can realize water-free internal formation of the storage battery, and further guarantees the good appearance and performance of the storage battery. However, the electrode liquid composed of humic acid as an additive in the patent document is an organic system, the disclosed storage battery electrolyte is not suitable for water-based zinc ion batteries, and the addition of humic acid additive in the electrolyte also does not realize the construction of a stable electrode-electrolyte interface to inhibit the disordered growth of zinc dendrites. SUMMARY

[0006] The technical problem solved by the present application is to provide a water-based zinc ion battery electrolyte containing a humic acid additive and a preparation method thereof. The method realizes the synergistic effect of multiple strategies by adding humic acid additive in the electrolyte to construct a stable electrode-electrolyte interface, makes the zinc deposition surface more flat, and inhibits the disordered growth of zinc dendrites, thereby improving the electrochemical stability and cycle life electrochemical performance of the water-based zinc ion battery. The present application has the characteristics of low cost and simple process, and has important significance for the commercialization of water-based zinc ion batteries.

[0007] The application adopts the following technical scheme to solve the above technical problems: a water-based zinc ion battery electrolyte containing furilic acid additive, wherein the content of furilic acid in the water-based zinc ion battery electrolyte is 0.1wt%-10wt%, preferably 1wt%, and the water-based zinc ion battery electrolyte containing furilic acid additive is suitable for a water-based zinc ion battery. Furilic acid is a natural high molecular organic acid containing rich carboxyl (-COOH), hydroxyl (-OH) and phenolic hydroxyl functional groups. The rich carboxyl of furilic acid can buffer the pH fluctuation of the zinc electrode interface. Furilic acid is used as an additive of the water-based zinc ion battery electrolyte, which can reconstruct the Helmholtz layer on the electrode surface, prevent direct contact between water and the zinc electrode, inhibit the occurrence of hydrogen evolution reaction and corrosion reaction, adjust the orientation of zinc deposition due to the presence of oxygen-containing functional groups, reduce the nucleation overpotential, more easily refine the zinc grains, and form a dense and uniform zinc deposition layer to achieve the goal of inhibiting zinc dendrites; on the other hand, furilic acid participates in the solvation process of zinc ions, reduces the activation energy of the electrode reaction, accelerates the electrode reaction rate, and reduces the polarization of the electrode interface. Compared with the water-based zinc ion battery without the additive, the water-based zinc ion battery assembled by the electrolyte containing the furilic acid additive can be stably cycled for more than 3000 hours.

[0008] Further, the water-based zinc ion battery electrolyte contains a zinc salt electrolyte, which is one or more of zinc sulfate, zinc tetrafluoroborate, zinc acetate, zinc nitrate or zinc chloride, preferably zinc sulfate.

[0009] Further, the concentration of the zinc salt electrolyte in the water-based zinc ion battery electrolyte is 0.5-3.5mol / L, preferably 1mol / L.

[0010] Further, the pH value of the water-based zinc ion battery electrolyte is 3.2-7, preferably 4.2-5.8.

[0011] A preparation method of a water-based zinc ion battery electrolyte containing furilic acid additive, the specific preparation process is as follows: under room temperature conditions, a soluble zinc salt and furilic acid are sequentially dissolved in deionized water, the temperature is raised to 60-70℃, stirring is carried out until complete dissolution, then the temperature is lowered to room temperature, the pH value of the mixed system is adjusted, and the obtained solution is filtered through a filter membrane with a pore size of less than 1μm to obtain the water-based zinc ion battery electrolyte containing furilic acid additive.

[0012] A water-based zinc ion battery, which comprises a positive electrode, a negative electrode, a separator and the above-mentioned water-based zinc ion battery electrolyte containing furilic acid additive, wherein the positive electrode active material is NH4V4O 10 , the negative electrode material is zinc foil, and the separator material is a glass fiber microporous filter membrane.

[0013] Compared with the prior art, the core advantages of the application include: 1. The present application adds fulvic acid (FA) additive in aqueous zinc ion battery electrolyte. The molecular structure of fulvic acid contains carboxyl (-COOH, about 15%-20%), hydroxyl (-OH, about 10%-15%), phenolic hydroxyl (-C6H4OH, about 8%-12%) and quinone group (C=O) and other polar functional groups. The lone pair electrons on the oxygen atom can form a coordination bond with Zn²⁺, changing the solvation structure of hydrated zinc ions. In the traditional aqueous zinc ion battery electrolyte, Zn²⁺ exists in the form of [Zn (H2O)6]²⁺, the solvation shell is tight and the water molecules are disordered, resulting in uneven interface energy during zinc deposition. From the perspective of thermodynamics, the deposition tends to the principle of minimum energy, and zinc deposition is prone to repeated deposition on the tip, eventually forming dendrites. In the aqueous zinc ion battery electrolyte containing fulvic acid, the fulvic acid molecules are coordinated with Zn²⁺ through carboxyl and hydroxyl groups to form [Zn(FA)(H2O) n ]²⁺ structure, the number of water molecules in the Zn²⁺ solvation shell is reduced, and the aromatic ring structure of fulvic acid provides steric hindrance, guiding Zn²⁺ to deposit in a two-dimensional layered growth mode on the electrode surface.

[0014] 2. The present application adds fulvic acid additive in aqueous zinc ion battery electrolyte. The carboxyl and phenolic hydroxyl groups of fulvic acid can buffer H⁺ concentration through protonation / deprotonation in the pH range of 3-10. When the electrolyte H + concentration decreases due to hydrogen evolution, fulvic acid releases protons (-COOH→-COO⁻ + H⁺); when H⁺ concentration is too high, fulvic acid captures protons through hydroxyl groups, maintaining electrolyte pH fluctuation <0.8 during high-rate charge and discharge, thereby inhibiting the production of alkaline by-products caused by the increase of pH due to hydrogen evolution reaction.

[0015] 3. The present application adds fulvic acid additive in aqueous zinc ion battery electrolyte. The adsorption energy of fulvic acid molecules on the zinc electrode surface is higher than that of H⁺, which preferentially occupies the high active sites on the electrode surface, reducing the reduction path of active water and H3O⁺.

[0016] 4. The present application adds fulvic acid additive in aqueous zinc ion battery electrolyte. Fulvic acid forms an inorganic-organic hybrid layer on the zinc electrode surface through chemical adsorption, in which fulvic acid molecules are coordinated with Zn²⁺. This film layer has self-repairing ability. When the protective layer is broken during electrode charge and discharge, fulvic acid molecules in the electrolyte can quickly re-adsorb and fill the defects, avoiding direct contact between zinc and water.

[0017] 5. The present application adds fulvic acid additive in aqueous zinc ion battery electrolyte, the inorganic-organic hybrid layer formed by fulvic acid molecules on the surface of zinc foil, the polar functional groups inside form uniform zinc ion transmission channel, which helps to eliminate dendrite growth caused by uneven electric field on the surface of zinc electrode during deposition, and improves the reversibility of zinc electrode in deposition / stripping process.

[0018] 6. The aqueous zinc ion battery electrolyte containing fulvic acid additive prepared by the present application shows excellent battery electrochemical performance whether it is assembled symmetric battery or assembled full battery. Experimental results show that the zinc / / zinc symmetric battery assembled by the electrolyte containing fulvic acid can also show 3000h of cycle stability under the conditions of current density of 0.5mA·cm -2 , area capacity of 0.5mAh·cm -2 , which is more than 7 times better than the comparative example 1.

[0019] 7. The additive fulvic acid used in the aqueous zinc ion battery electrolyte of the present application is mainly prepared from natural organic matter such as peat and lignite by alkali extraction-acid precipitation method, or by microbial fermentation of straw, sugarcane residue and other biomass by Trichoderma, Aspergillus and other microorganisms. The energy consumption of the production process is only 1 / 3 of that of synthetic polymer additives, and there is no use of harmful chemical reagents, low cost, green and environmentally friendly, and can be produced on a large scale, which is of great significance for the development of low-cost, high-performance, safe and environmentally friendly aqueous zinc ion battery energy storage system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The in-situ pH change of the symmetric battery assembled by the electrolyte of example 1 and comparative example 1 under 5mA·cm -2 .

[0021] Figure 2 The chronoamperometry curve of the symmetric battery assembled by the electrolyte of example 1 and comparative example 1 under overpotential of-150mV.

[0022] Figure 3 The LSV curve of the asymmetric battery assembled by the electrolyte of example 1 and comparative example 1.

[0023] Figure 4 The cycle performance comparison chart of the symmetric battery assembled by the electrolyte of example 1 and comparative example 1.

[0024] Figure 5 The coulombic efficiency comparison chart of the asymmetric battery assembled by the electrolyte of example 1 and comparative example 1.

[0025] Figure 6 The SEM image of the surface of zinc electrode (example 1 vs. comparative example 1), which shows that the deposition on the surface of the electrode of example 1 is more dense and has no obvious dendrite. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are intended to explain the present application only and are not intended to limit the present application.

[0027] The experimental methods used in the following examples are conventional methods unless otherwise specified. The reagents, materials, methods, and instruments used are conventional reagents, materials, methods, and instruments in the art unless otherwise specified, and are available to those skilled in the art through commercial channels.

[0028] When an equivalent, concentration, or other value or parameter is expressed in a range or a preferred range or a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value are specifically disclosed, regardless of whether the range is explicitly disclosed. Example 1

[0029] The aqueous zinc ion battery electrolyte of the present example is composed of zinc sulfate electrolyte, deionized water solvent, and fulvic acid additive, wherein the concentration of zinc sulfate is 1 mol / L, and the content of fulvic acid is 1 wt%. The zinc sulfate and the fulvic acid are sequentially dissolved in the deionized water at room temperature, and then stirred at 60°C until completely dissolved. After cooling to room temperature, the pH of the mixed system is adjusted to 4.2. The obtained solution is filtered through a 0.45 μm filter membrane to obtain the electrolyte. Example 2

[0030] The aqueous zinc ion battery electrolyte of the present example is composed of zinc sulfate electrolyte, deionized water solvent, and fulvic acid additive, wherein the concentration of zinc sulfate is 1 mol / L, and the content of fulvic acid is 0.2 wt%. The zinc sulfate and the fulvic acid are sequentially dissolved in the deionized water at room temperature, and then stirred at 60°C until completely dissolved. After cooling to room temperature, the pH of the mixed system is adjusted to 5.0. The obtained solution is filtered through a 0.22 μm filter membrane to obtain the electrolyte. Example 3

[0031] The aqueous zinc ion battery electrolyte of the present example is composed of zinc sulfate electrolyte, deionized water solvent, and fulvic acid additive, wherein the concentration of zinc sulfate is 1 mol / L, and the content of fulvic acid is 10 wt%. The zinc sulfate and the fulvic acid are sequentially dissolved in the deionized water at room temperature, and then stirred at 60°C until completely dissolved. After cooling to room temperature, the pH of the mixed system is adjusted to 5.5 using 0.1 M sodium hydroxide. The obtained solution is filtered through a 0.45 μm filter membrane to obtain the electrolyte. Example 4

[0032] The aqueous zinc ion battery electrolyte of the present embodiment is composed of zinc sulfate electrolyte, deionized water solvent and fulvic acid additive. The concentration of zinc sulfate is 1 mol / L, and the content of fulvic acid is 3 wt%. The zinc sulfate and fulvic acid are sequentially dissolved in deionized water at room temperature, and then stirred at 60°C until completely dissolved. After cooling to room temperature, the pH of the mixed system is adjusted to 4.2. The obtained solution is filtered through a 0.45 μm filter membrane to obtain the electrolyte.

[0033] Comparative Example 1 The aqueous zinc ion battery electrolyte of the present embodiment is composed of zinc sulfate electrolyte and deionized water solvent. The zinc sulfate is dissolved in deionized water at room temperature, and then stirred at 60°C until completely dissolved. After cooling to room temperature, the pH of the mixed system is adjusted to 4.2. The obtained solution is filtered through a filter membrane with a pore size of less than 0.55 μm to obtain the electrolyte.

[0034] Comparative Example 2 The aqueous zinc ion battery electrolyte of the present embodiment is composed of zinc sulfate electrolyte, deionized water solvent and citric acid additive containing abundant carboxyl groups. The zinc sulfate and citric acid are dissolved in deionized water at room temperature, and then stirred at 60°C until completely dissolved. After cooling to room temperature, the pH of the mixed system is adjusted to 4.2. The obtained solution is filtered through a filter membrane with a pore size of less than 0.55 μm to obtain the electrolyte.

[0035] The above prepared electrolyte is used to assemble Zn / / Zn symmetric battery and Zn / / NH4V4O 10 full battery, and charge-discharge test is carried out on a blue battery test system.

[0036] Symmetric battery assembly: metal zinc foil (diameter 16 mm, thickness 100 μm) is used as the positive and negative electrode sheets of the button cell. First, the positive electrode sheet is placed in the positive electrode shell, then the glass fiber separator is placed in, then 120 μL of the electrolyte of Example 1 and Comparative Example 1 is added, then the negative electrode sheet is placed, then the gasket and spring are placed in turn, and finally the negative electrode shell is buckled, and the battery is packaged using a battery sealing machine.

[0037] Asymmetric battery assembly: copper foil (diameter 16 mm, thickness 50 μm) is used as the positive electrode sheet of the button cell, and metal zinc sheet (diameter 16 mm, thickness 100 μm) is used as the negative electrode sheet. First, the positive electrode sheet is placed in the positive electrode shell, then the glass fiber separator is placed in, then 120 μL of the electrolyte of Example 1 and Comparative Example 1 is added, then the negative electrode sheet is placed, then the gasket and spring are placed in turn, and finally the negative electrode shell is buckled, and the battery is packaged using a battery sealing machine.

[0038] Performance and structure test: Figure 1Zn||Zn symmetric cells for the electrolyte of Comparative Example 1 and Example 1 were tested at 5 mA cm -2 pH change at current density. The pH of Comparative Example 1 increased significantly from the initial 4.2 to 5.85 within 20 hours and maintained a high pH during the subsequent cycles, as shown in Figure 1 Figure 1 (a). As shown in Figure 1 (b), the pH of Example 1 remained fairly stable under the same conditions, always maintaining between 4.3 and 5.1. Figure 1

[0039] Figure 2 CA curves for Example 1 and Comparative Example 1 at -150 mV overpotential. The current response of the symmetric cell containing the electrolyte of Comparative Example 1 still increased continuously as the plating process proceeded, indicating that the effective area of the electrode was increasing, which in turn explained the formation of zinc dendrites. In sharp contrast, the current response of the Zn||Zn symmetric cell containing the electrolyte of Example 1 increased relatively low, which verified that the fulvic acid can suppress the exposure of high-activity zinc, improve the kinetics of zinc deposition, and be conducive to obtaining a more compact and smoother zinc deposition surface.

[0040] Figure 3 LSV curves for the asymmetric cells assembled with the electrolytes of Example 1 and Comparative Example 1. Compared with Comparative Example 1, the zinc anode provided a lower HER potential in the electrolyte containing Example 1, indicating that the electrode was less prone to hydrogen evolution polarization reaction in the electrolyte containing the fulvic acid additive.

[0041] Figure 4 are 0.5 mA cm -2 , and the area capacity is 0.5 mAh cm -2 The symmetric cells assembled with the electrolytes of Example 1 and Comparative Example 1 were subjected to constant current charge-discharge tests under the conditions of a current density of 0.5 mA cm -2 , and a capacity of 5 mAh cm -2 . The symmetric button cell using the electrolyte of Comparative Example 1 only cycled to 350 hours, and the current decreased sharply, indicating that the dendrites generated during the operation of the battery directly pierced the separator and short-circuited. The symmetric button cell assembled with the electrolyte of Example 1 may be due to the generated fulvic acid interface layer blocking the direct contact of water and zinc, achieving dendrite-free zinc deposition, suppressing the hydrogen evolution reaction, and ultimately the symmetric cell can cycle for more than 3000 hours, which shows that the application of the electrolyte containing the electrolyte additive of the present application enables the battery to avoid the "tip effect", suppress the generation of dendrites, and alleviate the occurrence of side reactions, ultimately achieving high cycle stability of the aqueous zinc ion symmetric battery. In addition, the symmetric cells assembled with the electrolytes of Example 1 and Comparative Example 2 were tested at 5 mA cm -2 , and 5 mAh cm -2 . The symmetric cell assembled with the electrolyte of Example 1 can cycle for more than 3000 hours, while the symmetric cell assembled with the electrolyte of Comparative Example 2 only cycled for 1000 hours, which shows that the application of the electrolyte containing the electrolyte additive of the present application enables the battery to avoid the "tip effect", suppress the generation of dendrites, and alleviate the occurrence of side reactions, ultimately achieving high cycle stability of the aqueous zinc ion symmetric battery.The pair cell assembled by the electrolyte of Comparative Example 2 short-circuits at 101 hours, while the pair cell assembled by the electrolyte of Example 1 cycles more than 800 hours, which indicates that the abundant carboxyl group alone cannot effectively prolong the service life of the battery, and the synergistic effect of the carboxyl group, the hydroxyl group and the phenolic hydroxyl group contained in the fulvic acid additive is the key to prolonging the service life.

[0042] Figure 5 The Zn / / Cu asymmetric batteries assembled by the electrolytes of Example 1 and Comparative Example 1 are tested at a current density of 1 mA·cm -2 , and the area capacity is 0.5 mAh·cm -2 Under the condition, the comparison chart of the coulombic efficiency of the constant current charge and discharge test is shown. The results show that the asymmetric button cell assembled by the electrolyte of Example 1 can maintain a high average coulombic efficiency, and can be stably cycled for 1200 cycles, while the coulombic efficiency of the asymmetric button cell assembled by the electrolyte of Comparative Example 1 fluctuates greatly, indicating that the electrode / electrolyte interface is extremely unstable, and the battery short-circuits and fails at about 180 cycles, which indicates that the addition of the fulvic acid additive in the electrolyte of the aqueous zinc ion battery is beneficial to the uniform transmission of zinc ions at the anode / electrolyte interface, enhances the reversibility of zinc negative electrode deposition / stripping, and finally realizes the excellent cycle performance of the aqueous zinc ion asymmetric battery.

[0043] Figure 6 The SEM images of the Zn / / Zn symmetric batteries assembled by the electrolytes of Example 1 and Comparative Example 1 after 50 cycles. The zinc anode surface containing the fulvic acid additive is smoother, and most of the zinc is deposited horizontally on the zinc anode surface without obvious protrusions, indicating that the zinc ions are uniformly deposited on the zinc anode surface in an organized manner with the assistance of the fulvic acid additive, as shown in Figure 6 (b). As can be seen from Figure 6 (b), the zinc anode surface without the fulvic acid additive is deposited in a disorderly manner on the zinc anode surface, and there are obvious large particle zinc dendrites.

[0044] The above examples describe the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples. The above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the scope of the principles of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of protection of the present application.

Claims

1. An aqueous zinc-ion battery electrolyte containing fulvic acid additive, characterized in that: The fulvic acid content in the aqueous zinc ion electrolyte is 0.1wt% to 10wt%, and the aqueous zinc ion battery electrolyte containing fulvic acid additive is suitable for aqueous zinc ion batteries.

2. The aqueous zinc-ion battery electrolyte containing fulvic acid additive according to claim 1, characterized in that: The fulvic acid content in the aqueous zinc ion electrolyte is 1 wt%.

3. The aqueous zinc-ion battery electrolyte containing fulvic acid additive according to claim 1, characterized in that: The aqueous zinc-ion battery electrolyte contains a zinc salt electrolyte, which is one or more of zinc sulfate, zinc tetrafluoroborate, zinc acetate, zinc nitrate, or zinc chloride.

4. The aqueous zinc-ion battery electrolyte containing fulvic acid additive according to claim 3, characterized in that: The concentration of zinc salt electrolyte in the aqueous zinc-ion battery electrolyte is 0.5~3.5 mol / L.

5. The aqueous zinc-ion battery electrolyte containing fulvic acid additive according to claim 3, characterized in that: The concentration of zinc salt electrolyte in the aqueous zinc-ion battery electrolyte is 1 mol / L.

6. The aqueous zinc-ion battery electrolyte containing fulvic acid additive according to claim 1, characterized in that: The pH value of the aqueous zinc-ion battery electrolyte is 3.2~7.

7. The aqueous zinc-ion battery electrolyte containing fulvic acid additive according to claim 1, characterized in that: The pH value of the aqueous zinc-ion battery electrolyte is 4.2~5.

8.

8. The method for preparing the aqueous zinc-ion battery electrolyte containing fulvic acid additive according to any one of claims 1 to 7, characterized in that... The specific preparation process is as follows: soluble zinc salt and fulvic acid are dissolved in deionized water at room temperature, heated to 60~70℃ and stirred until completely dissolved, then cooled to room temperature and the pH value of the mixture is adjusted. The resulting solution is filtered through a filter membrane of less than 1μm to obtain an aqueous zinc-ion battery electrolyte containing fulvic acid additive.

9. An aqueous zinc-ion battery, characterized in that: The aqueous zinc-ion battery comprises a positive electrode, a negative electrode, a separator, and an aqueous zinc-ion battery electrolyte containing fulvic acid additive as described in any one of claims 1 to 7.

10. The aqueous zinc-ion battery according to claim 9, characterized in that: The positive electrode active material is NH4V4O 10 The negative electrode material is zinc foil, and the separator is a glass fiber microporous filter membrane.

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