An aqueous zinc-ion battery electrolyte, its preparation method and application

Abstract

The present invention discloses an aqueous zinc-ion battery electrolyte, a preparation method thereof and an application thereof, belonging to the technical field of zinc-ion batteries. The electrolyte includes 5-8 wt% of a vanadic acid additive; the vanadic acid additive uses Zn-sulfonated hydrogen bond organic framework as a carrier, and 4-6 wt% of vanadate is loaded on the surface of the carrier. The sulfonic acid groups contained in the carrier can cooperate with the vanadate to preferentially adsorb free water molecules in the aqueous electrolyte, reducing the erosion activity of the water molecules on the positive electrode material. The hydrogen bond network structure of the hydrogen bond organic framework can also selectively intercept the active water molecules, reducing the participation of water molecules in the redox dissolution of the vanadium-based positive electrode material. At the same time, the zinc metal ions doped in the carrier can cooperate with the strong polarity of the sulfonic acid group to regulate the solvation structure, reduce the interfacial impedance, and inhibit the growth of zinc dendrites, thereby improving the long-term stability of the aqueous zinc-ion battery, and obtaining an aqueous zinc-ion battery electrolyte that can both inhibit the dissolution of the positive electrode and stabilize the zinc negative electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of zinc-ion batteries, and particularly relates to an aqueous zinc-ion battery electrolyte, a preparation method thereof, and applications thereof. Background Art

[0002] With the increasing global demand for clean energy, developing a low-cost, environmentally friendly, and highly stable energy storage system has become one of the core tasks in the energy field. Among them, lithium-ion batteries have been widely used due to their high energy density. However, the lithium resources relied on by lithium-ion batteries are limited in reserves, and there are also problems such as high costs and flammability and explosibility of organic electrolytes, which severely limit their large-scale applications in grid-scale energy storage. In this context, aqueous zinc-ion batteries have gradually become a hot research object for the next-generation energy storage technology due to their advantages such as high intrinsic safety, rich raw material reserves, low costs, and environmental friendliness.

[0003] The core advantage of aqueous zinc-ion batteries lies in using water as the electrolyte solvent, which can fundamentally solve the safety hazards of traditional organic systems. Moreover, the positive electrode materials of aqueous zinc-ion batteries, such as vanadium oxides, exhibit high specific capacity due to their multi-electron redox characteristics.

[0004] However, during the actual application of aqueous zinc-ion batteries, positive electrode materials such as vanadium oxides are prone to dissolve in the aqueous electrolyte, resulting in capacity decay and a long-term decline in the stability of the battery. The negative electrode material will form dendrites due to side reactions or uneven deposition during the cycling process, leading to a short-circuit risk. For example, the solvent structuring of zinc salts in traditional electrolytes is prone to cause side reactions and gas production, and the optimization of electrolyte components is also equally important for indirectly improving the performance of the separator. Therefore, the optimization of the aqueous zinc-ion battery electrolyte plays an important role in improving the performance of zinc-ion batteries, and its improvement effect needs to take into account the dual requirements of inhibiting positive electrode dissolution and stabilizing the zinc negative electrode.

[0005] Existing research has tried to improve the problems of aqueous zinc-ion batteries by introducing vanadates to adjust the ion concentration of the electrolyte, but there are still problems such as precipitation caused by the local concentration process of vanadates. Therefore, there is an urgent need to study an aqueous zinc-ion electrolyte that can inhibit positive electrode dissolution and zinc dendrite growth by optimizing the electrolyte components, and at the same time optimize the mechanical strength and ion transport efficiency of the battery separator, break through the bottleneck of the cycling stability and safety of aqueous zinc-ion batteries, and provide a technical basis for the large-scale application of aqueous zinc-ion batteries. Summary of the Invention

[0006] The purpose of the present invention is to provide an aqueous zinc-ion battery electrolyte, a preparation method thereof, and applications thereof, so as to obtain an aqueous zinc-ion battery electrolyte that takes into account the functions of inhibiting positive electrode dissolution and stabilizing the zinc negative electrode.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] In a first aspect, the present invention provides an aqueous zinc-ion battery electrolyte, which includes 5-8 wt% of a vanadic acid additive; the vanadic acid additive is carried by a Zn-sulfonated hydrogen-bonded organic framework, and 4-6 wt% of vanadate is loaded on the surface of the carrier.

[0009] Preferably, the vanadate includes one or a combination of more of sodium vanadate, potassium vanadate, and zinc vanadate.

[0010] Preferably, the electrolyte further includes a basic electrolyte; the basic electrolyte includes one or a combination of more of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, zinc perchlorate, and lithium trifluoromethanesulfonate.

[0011] Preferably, the concentration of the basic electrolyte in the electrolyte is 1.5-2.5 mol / L.

[0012] Preferably, the viscosity of the electrolyte is 10000-15000 mPa·s.

[0013] By adopting the above technical solution, vanadium-based compounds on the surface of the positive electrode material of the aqueous zinc-ion battery will, during the charge and discharge cycle, due to the structural water molecules of hydrated zinc ions and polar water molecules such as free water in the electrolyte, have a strong interaction with the unsaturated coordination groups in its vanadium-based lattice, resulting in the dissolution of vanadium on the surface of the positive electrode material in the form of soluble ions, thereby causing the dissolution of the positive electrode material and the capacity attenuation of the zinc-ion battery.

[0014] The present invention adds a vanadic acid additive to the electrolyte of the aqueous zinc-ion battery. The introduction of vanadate can increase the concentration of vanadate ions in the electrolyte, thereby changing the coordination environment of hydrated zinc ions, reducing the number of coordinated water molecules, and can also adsorb free water molecules in the electrolyte, reducing the content of free water in the electrolyte, thereby weakening the erosion of water molecules on the vanadium-based lattice of the positive electrode material. And the addition of vanadate can also in-situ generate an insoluble interfacial layer on the surface of the positive electrode material, physically blocking the direct contact between the vanadium-based positive electrode material and the electrolyte, and inhibiting the dissolution of the positive electrode material.

[0015] However, directly adding vanadate easily leads to a local increase in the concentration of vanadate ions in the electrolyte, which easily forms insoluble precipitates with other cations, such as zinc vanadate. The occurrence of side reactions will induce the rapid growth of zinc dendrites, affecting the performance of the zinc-ion battery. Because loading vanadate on the carrier can effectively avoid the problem of uneven dispersion of vanadate, increase the exposure area of active sites, and is also beneficial to fixing vanadate, reducing the loss during cycling, and improving the stability of the electrolytic structure.

[0016] In the present invention, Zn-sulfonated hydrogen-bonded organic framework is selected as the carrier. The crystal structure of the hydrogen-bonded organic framework has high porosity and ordered pores, which can provide uniformly distributed active sites for the loading of vanadate. In an aqueous solvent, the hydrogen-bonded organic framework is in a metastable state and is not easily soluble, but its surface structure will gradually collapse, thus achieving the effect of slow release of vanadate, effectively avoiding the precipitation caused by the excessive local concentration of vanadate ions in the electrolyte, improving the dispersibility of vanadate in the electrolyte while exerting the function of vanadate, so as to improve the long-term stability of the zinc-ion battery.

[0017] The sulfonic acid groups on the surface of the sulfonated hydrogen-bonded organic framework have strong electronegativity, which can further optimize ion interactions. The sulfonic acid groups can form a hydrogen bond network between solvent molecules and water molecules in the solvation shell of zinc ions, capture some water molecules in the solvent, thereby regulating the solvation structure, reducing the overcoordination of solvent molecules and their direct contact with zinc ions, reducing the generation of side reactions, and synergistically with vanadate to further inhibit the dissolution reaction of the cathode material and stabilize the zinc anode, reducing the growth of zinc dendrites. The oxygen atoms in the sulfonic acid groups can further stabilize the framework structure due to their strong polarity and strong anchoring effect.

[0018] Moreover, the Zn-sulfonated hydrogen-bonded organic framework, the carrier of the vanadate additive in the present invention, is also doped with metal zinc ions, which can provide metal ions during the formation of the hydrogen-bonded organic framework, serving as a template or a coordination center to regulate the growth behavior of the crystal. Doping with zinc ions can also avoid introducing other cation impurities in the aqueous zinc-ion battery. Zinc ions can also act as a charge balance center, regulate the degree of dissociation of sulfonic acid groups, form an ordered ion transport channel, effectively realize the rapid transport of double carriers of zinc ions and hydrogen ions, reduce the interfacial impedance, and inhibit the growth of zinc dendrites on the zinc anode.

[0019] By adding a vanadate additive to the electrolyte of the aqueous zinc-ion battery in the present invention, the sulfonic acid groups and the loaded vanadate on the Zn-sulfonated hydrogen-bonded organic framework carrier can preferentially adsorb free water molecules in the aqueous electrolyte, thereby significantly reducing the erosion activity of water molecules on the cathode material. The hydrogen bond network structure of the hydrogen-bonded organic framework can also selectively intercept active water molecules, reducing the participation of water molecules in the redox dissolution of the vanadium-based cathode material. The vanadate loaded on the Zn-sulfonated hydrogen-bonded organic framework can be slowly released, improving the uniform dispersion in the electrolyte. The Zn-sulfonated hydrogen-bonded organic framework carrier is also doped with zinc ions, which can synergistically with the strong polarity of the sulfonic acid groups to regulate the solvation structure, reduce the interfacial impedance, and inhibit the growth of zinc dendrites, thereby improving the long-term stability of the aqueous zinc-ion battery.

[0020] The addition of the basic electrolyte can assist the vanadate additive to inhibit the growth of the cathode solvent and zinc dendrites, and play a role in helping the rapid transport of ions, thereby improving the rate performance of the zinc-ion battery.

[0021] Preferably, the raw materials of the Zn-sulfonated hydrogen-bonded organic framework include sulfonated terephthalic acid and zinc salt in a molar ratio of 1:(1.5-2).

[0022] Preferably, the zinc salt comprises a combination of one or more of zinc nitrate hexahydrate, zinc sulfate heptahydrate and zinc chloride.

[0023] Preferably, the vanadic acid additive is prepared according to the following method:

[0024] Preparation of Zn-sulfonated hydrogen-bonded organic framework: organic alcohol and water are mixed in dimethylformamide, sulfonated terephthalic acid and zinc salt are added, stirred and mixed at room temperature for 30 to 60 minutes, then reacted at 110 to 125° C. for 20 to 25 hours, cooled and crystallized, and then washed and dried to obtain Zn-sulfonated hydrogen-bonded organic framework;

[0025] Preparation of vanadic acid additive: dissolve vanadate in water, adjust the solution pH to 4-5.5, then immerse the Zn-sulfonated hydrogen bond organic framework in the solution, and stir at room temperature for 12-15 hours to obtain the vanadic acid additive.

[0026] Preferably, the organic alcohol includes a combination of one or more of methanol, ethanol and ethylene glycol.

[0027] Preferably, the mass volume ratio of sulfonated terephthalic acid to organic alcohol is 1 g: (30-35) mL.

[0028] By adopting the above technical scheme, the sulfonate and carboxylate ions of sulfonated terephthalic acid can form a hydrogen bond network with water molecules and organic alcohols. In this process, the organic alcohol can also act as a wetting agent to provide more hydroxyl functional groups. The zinc ions provide metal ions for the hydrogen bonded organic framework to promote crystal growth. Finally, the Zn-sulfonated hydrogen bonded organic framework is obtained by cooling and crystallization. Then, the Zn-sulfonated hydrogen bonded organic framework is immersed in a vanadate aqueous solution. Under acidic conditions, a large number of electronegative functional groups contained in the Zn-sulfonated hydrogen bonded organic framework can be combined with vanadium oxygen groups in the vanadate through coordination and hydrogen bonding, thereby increasing the interface stability between the two, so that the vanadate can be smoothly loaded on the surface of the Zn-sulfonated hydrogen bonded organic framework carrier, and the aggregation of the vanadate in the electrolyte is avoided.

[0029] The vanadic acid additive prepared by the above method preferentially adsorbs free water molecules in the aqueous electrolyte, reduces the corrosion activity of water molecules on the positive electrode material, and can also regulate the solvation structure, reduce the interfacial impedance, and inhibit the growth of zinc dendrites. Finally, an aqueous zinc ion battery electrolyte is obtained that can take into account the inhibition of positive electrode dissolution and the stabilization of zinc negative electrode.

[0030] Second aspect, the present invention provides a method for preparing an aqueous zinc-ion battery electrolyte, including the following preparation steps:

[0031] Dissolve the basic electrolyte in deionized water to obtain a premixed solution; add a vanadic acid additive to the premixed solution and stir evenly to obtain the aqueous zinc-ion battery electrolyte.

[0032] Third aspect, the present invention provides an application of an aqueous zinc-ion battery electrolyte, and this electrolyte is applied to a vanadium-based aqueous zinc-ion battery; the liquid injection process of the electrolyte in the vanadium-based aqueous zinc-ion battery includes:

[0033] S1. Configure the aqueous zinc-ion battery electrolyte obtained above into an electrolyte aqueous solution with a viscosity of 8000 - 12000 mPa·s;

[0034] S2. Coat the electrolyte aqueous solution on the surface of the aqueous separator, and obtain a pretreated separator after drying;

[0035] S3. After laminating the pretreated separator, the positive electrode sheet and the negative electrode sheet, then inject the aqueous zinc-ion battery electrolyte to complete the liquid injection.

[0036] Preferably, in step S2, the electrolyte aqueous solution can be coated on the aqueous separator twice or more times to obtain a pretreated separator.

[0037] Preferably, the aqueous separator includes any one of a glass fiber separator, a cellulose separator, and a non-woven fabric separator; the average pore size of the aqueous separator is 2.76 - 3 μm, and the thickness is 200 - 600 μm.

[0038] Preferably, the positive electrode sheet includes a stainless steel foil coated with one or more combinations of vanadium dioxide, vanadium pentoxide, and vanadate; the thickness of the vanadium-based material coated on the positive electrode material is 10 - 50 μm.

[0039] Preferably, the negative electrode sheet is a zinc foil subjected to surface treatment; the surface treatment method includes one of polymer coating and roughening treatment.

[0040] By adopting the above technical solutions, the electrolyte added with the vanadic acid additive can effectively inhibit the dissolution of the positive electrode, and can also stabilize the zinc negative electrode and inhibit the growth of zinc dendrites, which plays an important role in improving the service life, electrochemical performance, and long-term stability of the aqueous zinc-ion battery. However, the viscosity of the electrolyte containing the vanadic acid additive increases, which makes it more difficult to inject liquid during the process of assembling the battery. Therefore, when applying this aqueous zinc-ion battery electrolyte, the present invention also provides a liquid injection method, which can not only optimize the liquid injection process, but also improve the performance of the aqueous separator, and obtain a zinc-ion battery with more excellent performance.

[0041] Specifically, the present invention first adjusts the viscosity of the electrolyte to a suitable value, and then coats it on the surface of the aqueous diaphragm. For the electrolyte with high viscosity, the coating method is simpler and saves process time. Conventional injection methods often require vacuum injection and other means for such high-viscosity electrolytes. The present invention saves this step by coating the surface of the diaphragm. The coating operation can play a certain compression and solidification role. After lamination, conventional injection methods are used for injection, so that the vanadic acid additive in the aqueous zinc ion battery electrolyte can be evenly distributed in the zinc ion battery.

[0042] Beneficial effects of the present invention:

[0043] 1. The present invention provides an aqueous zinc ion battery electrolyte, wherein a vanadic acid additive is added to the electrolyte, wherein the vanadic acid additive uses a Zn-sulfonated hydrogen-bonded organic framework as a carrier and is loaded with vanadate, wherein the sulfonic acid groups contained in the carrier can cooperate with vanadate to preferentially adsorb free water molecules in the aqueous electrolyte, thereby reducing the corrosion activity of water molecules on the positive electrode material, and the hydrogen-bonded network structure of the hydrogen-bonded organic framework can also selectively intercept active water molecules, thereby reducing the participation of water molecules in the redox dissolution of vanadium-based positive electrode materials. At the same time, the zinc metal ions doped in the carrier can cooperate with the strong polarity of the sulfonic acid group, regulate the solvation structure, reduce the interfacial impedance, and inhibit the growth of zinc dendrites, thereby improving the long-term stability of the aqueous zinc ion battery, and obtaining an aqueous zinc ion battery electrolyte that can take into account both the inhibition of positive electrode dissolution and the stabilization of the zinc negative electrode.

[0044] 2. The present invention also provides an application of an aqueous zinc ion battery electrolyte, which can be applied to a vanadium-based aqueous zinc ion battery, and since the electrolyte with the vanadic acid additive has a high viscosity, the present invention also provides a liquid injection method, which effectively solves the problem of high viscosity of the electrolyte and difficulty in liquid injection. Specifically, the present invention adopts a coating method to first coat the electrolyte on the surface of the aqueous diaphragm, first performs a certain compression solidification, and then adopts a conventional liquid injection method, which can not only optimize the liquid injection process, but also enable the vanadic acid additive to be evenly distributed in the zinc ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be further described below in conjunction with the accompanying drawings.

[0046] Figure 1 It is a discharge specific capacity change curve diagram of the battery long cycle performance test at a normal rate (0.5C) in the cycle performance test of Example 1, Comparative Example 3 and Comparative Example 5 of the present invention;

[0047] Figure 2 It is a discharge specific capacity change curve diagram of Example 1, Comparative Example 3 and Comparative Example 5 in the high rate performance test of the present invention and the high rate (3C) battery long cycle performance test. DETAILED DESCRIPTION

[0048] The following will describe the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0049] Preparation Example

[0050] Preparation Example 1, a vanadic acid additive, is prepared by the following method:

[0051] Mix 2 mL of ethanol and 1 mL of water in 8 mL of dimethylformamide, add 0.25 mmol of sulfonated terephthalic acid and 0.45 mmol of zinc nitrate hexahydrate, stir and mix at room temperature for 40 min, then react at 120 °C for 24 h. After cooling and crystallization, Zn-sulfonated hydrogen-bonded organic framework is obtained through washing and drying;

[0052] Take 100 mg of sodium vanadate and dissolve it in water to prepare a solution with a concentration of 0.1 mol / L, adjust the pH value of the solution to 5, and then immerse the above-obtained Zn-sulfonated hydrogen-bonded organic framework in the solution. After stirring at room temperature for 12 h, the vanadic acid additive is obtained.

[0053] The average loading amount of vanadate on the surface of the Zn-sulfonated hydrogen-bonded organic framework is 5 wt%.

[0054] Preparation Example 2, a vanadic acid additive, is different from Preparation Example 1 only in that the addition amount of zinc nitrate hexahydrate is 0.375 mmol.

[0055] Preparation Example 3, a vanadic acid additive, is different from Preparation Example 1 only in that the addition amount of zinc nitrate hexahydrate is 0.5 mmol.

[0056] Preparation Example 4, a vanadic acid additive, is different from Preparation Example 1 only in that the addition amount of sodium vanadate is 80 mg, and the average loading amount of vanadate on the surface of the obtained Zn-sulfonated hydrogen-bonded organic framework is 4 wt%.

[0057] Preparation Example 5, a vanadic acid additive, is different from Preparation Example 1 only in that the addition amount of sodium vanadate is 120 mg, and the average loading amount of vanadate on the surface of the obtained Zn-sulfonated hydrogen-bonded organic framework is 6 wt%.

[0058] Preparation Example 6, a vanadic acid additive, is prepared by the following method:

[0059] Mix 2 mL of ethanol and 1 mL of water in 8 mL of dimethylformamide, add 0.25 mmol of sulfonated terephthalic acid, stir and mix at room temperature for 40 min, then react at 120 °C for 24 h. After cooling and crystallization, wash and dry to obtain the sulfonated hydrogen-bonded organic framework;

[0060] Dissolve 100 mg of sodium vanadate in water to prepare a solution with a concentration of 0.1 mol / L, adjust the pH value of the solution to 5, and then immerse the above-obtained sulfonated hydrogen-bonded organic framework in the solution and stir at room temperature for 12 h to obtain the vanadic acid additive.

[0061] The average loading amount of vanadate on the surface of the sulfonated hydrogen-bonded organic framework is 5 wt%.

[0062] Preparation Example 7, a vanadic acid additive, is prepared by the following method:

[0063] Mix 2 mL of ethanol and 1 mL of water in 8 mL of dimethylformamide, add 0.25 mmol of terephthalic acid and 0.45 mmol of zinc nitrate hexahydrate, stir and mix at room temperature for 40 min, then react at 120 °C for 24 h. After cooling and crystallization, wash and dry to obtain the Zn-hydrogen-bonded organic framework;

[0064] Dissolve 100 mg of sodium vanadate in water to prepare a solution with a concentration of 0.1 mol / L, adjust the pH value of the solution to 5, and then immerse the above-obtained Zn-hydrogen-bonded organic framework in the solution and stir at room temperature for 12 h to obtain the vanadic acid additive.

[0065] The average loading amount of vanadate on the surface of the Zn-hydrogen-bonded organic framework is 5 wt%.

[0066] Preparation Example 8, a vanadic acid additive, is different from Preparation Example 1 only in that the addition amount of sodium vanadate is 40 mg, and the average loading amount of vanadate on the surface of the obtained Zn-sulfonated hydrogen-bonded organic framework is 2 wt%.

[0067] Preparation Example 9, a vanadic acid additive, is different from Preparation Example 1 only in that the addition amount of sodium vanadate is 160 mg, and the average loading amount of vanadate on the surface of the obtained Zn-sulfonated hydrogen-bonded organic framework is 8 wt%.

[0068] Examples

[0069] Example 1, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, are prepared according to the following scheme:

[0070] Dissolve zinc trifluoromethanesulfonate at 1.5 mol / L and zinc sulfate at 0.5 mol / L in deionized water to obtain a premixed solution; add the vanadic acid additive prepared in Preparation Example 1 to the premixed solution and stir evenly to obtain an aqueous zinc-ion battery electrolyte. The electrolyte contains 7 wt% of the vanadic acid additive, and the viscosity of the electrolyte is 11000 mPa·s.

[0071] Configure the obtained aqueous zinc-ion battery electrolyte into an electrolyte aqueous solution with a viscosity of 9000 mPa·s; coat the electrolyte aqueous solution on the surface of a glass fiber separator (average pore size is 2.76 μm, thickness is 350 μm), and obtain a pretreated separator after drying at 60°C.

[0072] Stack the positive electrode sheet (V2O5 / stainless steel foil), the pretreated separator, and the negative electrode sheet (roughened zinc foil) in sequence, then inject the obtained aqueous zinc-ion battery electrolyte, complete the liquid injection, and encapsulate it into a CR2032 button battery.

[0073] Example 2, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, are prepared according to the following scheme:

[0074] Dissolve zinc trifluoromethanesulfonate at 1 mol / L and zinc sulfate at 0.5 mol / L in deionized water to obtain a premixed solution; add the vanadic acid additive prepared in Preparation Example 1 to the premixed solution and stir evenly to obtain an aqueous zinc-ion battery electrolyte. The electrolyte contains 5 wt% of the vanadic acid additive, and the viscosity of the electrolyte is 10000 mPa·s.

[0075] Configure the obtained aqueous zinc-ion battery electrolyte into an electrolyte aqueous solution with a viscosity of 8000 mPa·s; coat the electrolyte aqueous solution on the surface of a glass fiber separator (average pore size is 2.76 μm, thickness is 350 μm), and obtain a pretreated separator after drying at 60°C.

[0076] Stack the positive electrode sheet (V2O5 / stainless steel foil), the pretreated separator, and the negative electrode sheet (roughened zinc foil) in sequence, then inject the obtained aqueous zinc-ion battery electrolyte, complete the liquid injection, and encapsulate it into a CR2032 button battery.

[0077] Example 3, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, are prepared according to the following scheme:

[0078] Dissolve zinc trifluoromethanesulfonate at 2 mol / L and zinc sulfate at 0.3 mol / L in deionized water to obtain a premixed solution; add the vanadic acid additive prepared in Preparation Example 1 to the premixed solution and stir evenly to obtain an aqueous zinc-ion battery electrolyte. The electrolyte contains 8 wt% of the vanadic acid additive, and the viscosity of the electrolyte is 14000 mPa·s.

[0079] The aqueous electrolyte solution of the aqueous zinc-ion battery obtained above is configured into an electrolyte aqueous solution with a viscosity of 10,000 mPa·s; the electrolyte aqueous solution is coated on the surface of a glass fiber separator (average pore size is 2.76 μm and thickness is 350 μm), and after drying at 60 °C, a pretreated separator is obtained.

[0080] Stack the positive electrode sheet (V2O5 / stainless steel foil), the pretreated separator, and the negative electrode sheet (roughened zinc foil) in sequence, then inject the aqueous electrolyte solution of the aqueous zinc-ion battery obtained above, complete the liquid injection, and encapsulate it into a CR2032 button battery.

[0081] Example 4, an aqueous electrolyte solution of an aqueous zinc-ion battery and an aqueous zinc-ion battery, are prepared according to the following scheme:

[0082] Zinc trifluoromethanesulfonate at 1.5 mol / L and zinc sulfate at 0.5 mol / L are dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 is added to the premixed solution and stirred evenly to obtain the aqueous electrolyte solution of the aqueous zinc-ion battery, wherein the electrolyte solution contains 7 wt% of the vanadic acid additive and the viscosity of the electrolyte solution is 11,000 mPa·s.

[0083] The aqueous electrolyte solution of the aqueous zinc-ion battery obtained above is configured into an electrolyte aqueous solution with a viscosity of 9,000 mPa·s; the electrolyte aqueous solution is coated on the surface of a glass fiber separator (average pore size is 2.76 μm and thickness is 350 μm), pre-dried at 50 °C, then subjected to secondary coating, and dried again at 60 °C to obtain a pretreated separator.

[0084] Stack the positive electrode sheet (V2O5 / stainless steel foil), the pretreated separator, and the negative electrode sheet (roughened zinc foil) in sequence, then inject the aqueous electrolyte solution of the aqueous zinc-ion battery obtained above, complete the liquid injection, and encapsulate it into a CR2032 button battery.

[0085] Example 5, an aqueous electrolyte solution of an aqueous zinc-ion battery and an aqueous zinc-ion battery, is different from Example 1 only in that the vanadic acid additive prepared in Preparation Example 2 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0086] Example 6, an aqueous electrolyte solution of an aqueous zinc-ion battery and an aqueous zinc-ion battery, is different from Example 1 only in that the vanadic acid additive prepared in Preparation Example 3 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0087] Example 7, an aqueous electrolyte solution of an aqueous zinc-ion battery and an aqueous zinc-ion battery, is different from Example 1 only in that the vanadic acid additive prepared in Preparation Example 4 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0088] Example 8, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the vanadic acid additive prepared in Preparation Example 5 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0089] Comparative Example

[0090] Comparative Example 1, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the vanadic acid additive prepared in Preparation Example 6 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0091] Comparative Example 2, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the vanadic acid additive prepared in Preparation Example 7 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0092] Comparative Example 3, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the vanadic acid additive prepared in Preparation Example 8 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0093] Comparative Example 4, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the vanadic acid additive prepared in Preparation Example 9 is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0094] Comparative Example 5, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that vanadate is used to replace the vanadic acid additive prepared in Preparation Example 1 in an equal amount.

[0095] Comparative Example 6, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the addition amount of the vanadic acid additive prepared in Preparation Example 1 in the aqueous zinc-ion battery electrolyte is 2 wt%.

[0096] Comparative Example 7, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, which are different from those of Example 1 only in that the addition amount of the vanadic acid additive prepared in Preparation Example 1 in the aqueous zinc-ion battery electrolyte is 10 wt%.

[0097] Comparative Example 8, an aqueous zinc-ion battery electrolyte and an aqueous zinc-ion battery, are prepared according to the following scheme:

[0098] Zinc trifluoromethanesulfonate at 1.5 mol / L and zinc sulfate at 0.5 mol / L are dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 is added to the premixed solution and stirred evenly to obtain the aqueous zinc-ion battery electrolyte, wherein the electrolyte contains 7 wt% of the vanadic acid additive and the viscosity of the electrolyte is 11000 mPa·s.

[0099] Stack the positive electrode sheet (V2O5 / stainless steel foil), glass fiber separator (average pore size of 2.76 μm and thickness of 350 μm), and negative electrode sheet (roughened zinc foil) in sequence, inject the aqueous zinc-ion battery electrolyte obtained above by vacuum injection, complete the injection, and encapsulate it into a CR2032 button battery.

[0100] Performance detection test

[0101] 1. Cycling performance test: Activate for 10 charge-discharge cycles under the conditions of a 0.1C rate and a voltage window of 0.3 - 1.7V to form a uniform SEI film; then, under the conditions of a 0.5C rate and a voltage window of 0.3 - 1.7V, test the capacity retention rate of the battery samples obtained in the examples and comparative examples after 100 cycles.

[0102] 2. High-rate performance test: Activate for 10 charge-discharge cycles under the conditions of a 0.1C rate and a voltage window of 0.3 - 1.7V to form a uniform SEI film; then, under the conditions of a 3C rate and a voltage window of 0.3 - 1.7V, test the capacity retention rate of the battery samples obtained in the examples and comparative examples after 500 cycles.

[0103] The above test results are shown in Table 1:

[0104] Table 1 Test results of performance detection

[0105]

[0106] According to Table 1, combining Example 1, Example 4, and Comparative Example 8, it can be seen that the cycling performance and rate performance of Example 4 are increased compared to Example 1, and the cycling performance and rate performance of Comparative Example 8 are decreased compared to Example 1. The reason is that in Example 4, the electrolyte is coated on the surface of the separator by the method of secondary coating, which can make the distribution of vanadic acid additives more uniform; in Comparative Example 8, the conventional injection method is used, which not only has a complex preparation process and is not conducive to the uniform distribution of the electrolyte in the positive and negative electrode sheets and the separator, thus affecting the battery performance.

[0107] Combining Example 1 and Comparative Example 1, it can be seen that the various performances of Comparative Example 1 are decreased compared to Example 1. The reason is that the vanadic acid additive in the aqueous zinc-ion battery electrolyte obtained in Comparative Example 1 does not have zinc ions doped on its vanadate carrier. On the one hand, the crystal growth process of the carrier lacks the optimization and adjustment of zinc ions, which affects the structural stability of the hydrogen-bonded organic framework; on the other hand, the lack of the coordination and charge balance effects of zinc ions is not conducive to reducing the interfacial impedance and difficult to inhibit the dendritic growth of the zinc negative electrode, thus affecting the battery performance.

[0108] Combined with Example 1 and Comparative Example 2, it can be seen that the various performances of Comparative Example 2 are decreased compared with those of Example 1. The reason is that for the vanadic acid additive in the aqueous zinc-ion battery electrolyte obtained in Comparative Example 2, its vanadate carrier adopts a Zn-hydrogen bond organic framework, and the hydrogen bond organic framework is not sulfonated, which will reduce the ability of the vanadic acid additive to capture free water molecules in the water solvent, resulting in a decrease in the performance of regulating the dissolution structure, an increase in side reactions, and a decrease in the ability to inhibit the dissolution of the positive electrode material.

[0109] Combined with Example 1, Comparative Example 3 and Comparative Example 4, it can be seen that the various performances of Comparative Example 3 and Comparative Example 4 are decreased compared with those of Example 1. The reason is that in Comparative Example 3 and Comparative Example 4, the loading amount of vanadate in the vanadic acid additive is adjusted outside the range. The decrease in the vanadate loading amount results in a corresponding decrease in the ability to change the coordination environment of hydrated zinc ions and adsorb free water molecules, and the electrochemical performance decreases accordingly. In Comparative Example 4, the loading amount of vanadate is increased, but the active sites on the carrier surface are limited. The loading of a large amount of vanadate will affect the pore structure of the carrier, thereby affecting the mass transfer effect, and will also lead to a decrease in the activity of the vanadic acid additive and a decrease in the battery performance.

[0110] Combined with Example 1 and Comparative Example 5, Figure 1 and Figure 2 , it can be seen that the change trend of the various performances and specific capacity of Comparative Example 5 is decreased compared with that of Example 1. The reason is that in Comparative Example 5, the vanadate added to the aqueous zinc-ion battery electrolyte is not carrier-loaded and is directly added to the electrolyte. During long-term cycling, the vanadate will agglomerate in large amounts, resulting in too high a local concentration, causing precipitation, inducing side reactions, and decreasing the stability of the zinc negative electrode, thus affecting the battery performance.

[0111] Combined with Example 1, Comparative Example 6 and Comparative Example 7, it can be seen that the various performances of Comparative Example 6 and Comparative Example 7 are decreased compared with those of Example 1. The reason is that in Comparative Example 6, the addition amount of the vanadic acid additive in the aqueous zinc-ion battery electrolyte is reduced, resulting in a corresponding decrease in the ability to inhibit the dissolution of the positive electrode and stabilize the zinc negative electrode, and the battery performance decreases. In Comparative Example 7, the addition amount of the vanadic acid additive in the aqueous zinc-ion battery electrolyte is increased, which will cause agglomeration and is instead not conducive to the uniform distribution of the vanadic acid additive.

[0112] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0113] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An aqueous zinc-ion battery electrolyte, characterized in that, The electrolyte contains 5-8 wt% of vanadic acid additive; the vanadic acid additive uses Zn-sulfonated hydrogen bond organic framework as a carrier, and 4-6 wt% of vanadate is loaded on the surface of the carrier; The raw materials of the Zn-sulfonated hydrogen bond organic framework include sulfonated terephthalic acid and zinc salt with a molar ratio of 1:(1.5-2); The Zn-sulfonated hydrogen bond organic framework is prepared by the following method: mixing organic alcohol and water in dimethylformamide, adding sulfonated terephthalic acid and zinc salt, stirring and mixing at room temperature for 30-60 min, then reacting at 110-125 °C for 20-25 h, after cooling and crystallization, washing and drying to obtain the Zn-sulfonated hydrogen bond organic framework.

2. The aqueous zinc ion battery electrolyte according to claim 1, characterized in that, The vanadate includes one or a combination of more of sodium vanadate, potassium vanadate and zinc vanadate.

3. The aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The zinc salt includes one or a combination of more of zinc nitrate hexahydrate, zinc sulfate heptahydrate and zinc chloride.

4. The aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The vanadic acid additive is prepared by the following method: Preparation of vanadic acid additive: Dissolve the vanadate in water, adjust the pH value of the solution to 4-5.5, then immerse the Zn-sulfonated hydrogen bond organic framework in the solution, and stir at room temperature for 12-15 h to obtain the vanadic acid additive.

5. The aqueous zinc ion battery electrolyte according to claim 1, characterized in that, The electrolyte also contains a basic electrolyte; the basic electrolyte includes one or a combination of more of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, zinc perchlorate and lithium trifluoromethanesulfonate.

6. The aqueous zinc ion battery electrolyte according to claim 5, characterized in that, The concentration of the basic electrolyte in the electrolyte is 1.5-2.5 mol / L.

7. The aqueous zinc-ion battery electrolyte according to claim 1, characterized in that, The viscosity of the electrolyte is 10000-15000 mPa·s.

8. A method for preparing an aqueous zinc-ion battery electrolyte according to any one of claims 1 to 7, characterized in that, It includes the following preparation steps: Dissolve the basic electrolyte in deionized water to obtain a premixed solution; add the vanadic acid additive to the premixed solution and stir evenly to obtain the aqueous zinc ion battery electrolyte.

9. Application of the aqueous zinc ion battery electrolyte according to any one of claims 1 to 7, characterized in that, The electrolyte is applied to a vanadium-based aqueous zinc ion battery; The liquid injection process of the electrolyte in the vanadium-based aqueous zinc ion battery includes: S1. Configure the aqueous zinc ion battery electrolyte described in any one of claims 1-7 into an electrolyte aqueous solution with a viscosity of 8000-12000 mPa·s; S2. Coat the electrolyte aqueous solution on the surface of the aqueous separator, and dry it to obtain a pretreated separator; S3. After laminating the pretreated separator, the positive electrode sheet and the negative electrode sheet, inject the aqueous zinc ion battery electrolyte to complete the liquid injection.

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