Aqueous zinc ion battery electrolyte and preparation method and application thereof

Abstract

The invention discloses an aqueous zinc ion battery electrolyte as well as a preparation method and application thereof, and belongs to the technical field of zinc ion batteries. The vanadic acid additive takes a Zn-sulfonated hydrogen bond organic framework as a carrier, and 4-6wt% of vanadate is loaded on the surface of the carrier. Sulfonic acid groups contained in the carrier can cooperate with vanadate to preferentially adsorb free water molecules in an aqueous electrolyte, the erosion activity of the water molecules on the positive electrode material is reduced, a hydrogen bond network structure of the hydrogen bond organic framework can selectively intercept active water molecules, and the water molecules are prevented from participating in oxidation reduction dissolution of the vanadium-based positive electrode material. Meanwhile, the zinc metal ions doped in the carrier can cooperate with the strong polarity of the sulfonic group, regulate and control the solvation structure, reduce the interface impedance and inhibit the growth of zinc dendrites, so that the long-term stability of the aqueous zinc ion battery is improved, and the aqueous zinc ion battery electrolyte capable of inhibiting the dissolution of a positive electrode and stabilizing a zinc negative electrode is obtained.

Description

Technical Field

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

[0002] With the growing 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 are widely used because of their high energy density. However, the lithium resources that lithium-ion batteries rely on are limited in reserves, and there are also problems such as high cost and flammable and explosive organic electrolytes, which seriously limit their large-scale application in grid-level energy storage. In this context, aqueous zinc-ion batteries have gradually become a hot research object for the next generation of energy storage technology due to their advantages such as high intrinsic safety, abundant raw material reserves, low cost and environmental friendliness.

[0003] The core advantage of aqueous zinc-ion batteries is that they use water as the electrolyte solvent, which can fundamentally solve the safety risks of traditional organic systems. In addition, the positive electrode materials of aqueous zinc-ion batteries, such as vanadium oxide, exhibit high specific capacity due to their multi-electron redox properties.

[0004] However, in the actual application of aqueous zinc-ion batteries, positive electrode materials such as vanadium oxides are easily dissolved in aqueous electrolytes, resulting in capacity decay and a decrease in the long-term stability of the battery; negative electrode materials will form dendrites due to side reactions or uneven deposition during the cycle, causing short circuit risks. For example, the solvent structure of zinc salts in traditional electrolytes is prone to side reactions and gas production, and the optimization of electrolyte components is also important for the indirect improvement of diaphragm performance. Therefore, the optimization of aqueous zinc-ion battery electrolytes plays an important role in improving the performance of zinc-ion batteries, and its improvement effect needs to take into account the dual needs of inhibiting the dissolution of the positive electrode and stabilizing the zinc negative electrode.

[0005] Existing research has improved the problems of aqueous zinc-ion batteries by introducing vanadates to adjust the electrolyte ion concentration, but there is still the problem of precipitation caused by the local concentration process of vanadates. Therefore, it is urgent to study an aqueous zinc-ion electrolyte that can suppress the dissolution of the positive electrode and the growth of zinc dendrites by optimizing the electrolyte components, while optimizing the mechanical strength and ion transmission efficiency of the battery separator, breaking through the bottleneck of the cycle stability and safety of aqueous zinc-ion batteries, and providing a technical basis for the large-scale application of aqueous zinc-ion batteries. Summary of the invention

[0006] The object of the present invention is to provide an aqueous zinc ion battery electrolyte and a preparation method and application thereof, so as to obtain an aqueous zinc ion battery electrolyte that can inhibit the dissolution of the positive electrode and stabilize the zinc negative electrode.

[0007] The purpose of the present invention can be achieved through the following technical solutions: In a first aspect, the present invention provides an aqueous zinc ion battery electrolyte, which includes 5 to 8 wt % of a vanadic acid additive; the vanadic acid additive uses a Zn-sulfonated hydrogen-bonded organic framework as a carrier, and the surface of the carrier is loaded with 4 to 6 wt % of vanadate.

[0008] Preferably, the vanadate includes a combination of one or more of sodium vanadate, potassium vanadate and zinc vanadate.

[0009] Preferably, the electrolyte also includes a basic electrolyte; the basic electrolyte includes a combination of one or more of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, zinc perchlorate and lithium trifluoromethanesulfonate.

[0010] Preferably, the concentration of the basic electrolyte in the electrolyte is 1.5 to 2.5 mol / L.

[0011] Preferably, the viscosity of the electrolyte is 10000-15000 mPa·s.

[0012] By adopting the above technical scheme, the vanadium-based compounds on the surface of the positive electrode material of the aqueous zinc-ion battery will dissolve in the form of soluble ions during the charge and discharge cycle because the structural water molecules of the hydrated zinc ions and the polar water molecules such as the solvent free water in the electrolyte will have a strong interaction with the unsaturated coordination groups in the vanadium-based lattice, thereby causing the vanadium on the surface of the positive electrode material to dissolve in the form of soluble ions, thereby causing the positive electrode material to dissolve and the capacity of the zinc-ion battery to decay.

[0013] 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, reduce the content of free water in the electrolyte, and thus weaken the corrosion of water molecules on the vanadium-based lattice of the positive electrode material. In addition, the addition of vanadate can also generate an insoluble interface layer in situ 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.

[0014] However, directly adding vanadates can easily lead to a local increase in the concentration of vanadate ions in the electrolyte, and easily form insoluble precipitation with other cations, such as zinc vanadate. The occurrence of side reactions can induce the rapid growth of zinc dendrites, affecting the performance of zinc ion batteries. Because vanadates are loaded on carriers, the problem of uneven dispersion of vanadates can be effectively avoided, the exposed area of ​​active sites can be increased, and it is also beneficial to fix vanadates, reduce loss during circulation, and improve the stability of the electrolytic structure.

[0015] The present invention selects a Zn-sulfonated hydrogen-bonded organic framework as a 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 dissolved, but the surface structure gradually collapses, thereby achieving the effect of sustained release of vanadate, effectively avoiding the precipitation caused by excessive local concentration of vanadate ions in the electrolyte, and 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.

[0016] The sulfonic acid groups on the surface of the sulfonated hydrogen-bonded organic framework have strong electronegativity, which can further optimize ionic interactions. The sulfonic acid groups can form a hydrogen bond network with solvent molecules and water molecules in the solubilized shell of zinc ions, capture some water molecules in the solvent, and thus regulate the solvation structure, reduce the over-coordination of solvent molecules, and the direct contact between them and zinc ions, reduce the generation of side reactions, and cooperate with vanadates to further inhibit the dissolution reaction of the positive electrode material and stabilize the zinc negative electrode, 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.

[0017] In addition, the carrier Zn-sulfonated hydrogen-bonded organic framework of the vanadic acid additive of the present invention is doped with metal zinc ions, which can provide metal ions in the formation process of the hydrogen-bonded organic framework as a template or coordination center to regulate the growth behavior of the crystal. The use of zinc ions for doping can also avoid the introduction of other cationic impurities in the aqueous zinc ion battery. The zinc ions can also serve as a charge balance center to adjust the dissociation degree of the sulfonic acid group, form an orderly ion transmission channel, effectively realize the rapid dual-carrier transmission of zinc ions and hydrogen ions, reduce the interface impedance, and inhibit the growth of zinc dendrites at the zinc negative electrode.

[0018] The present invention adds a vanadic acid additive to the aqueous zinc ion battery electrolyte, and can utilize the sulfonic acid groups on the Zn-sulfonated hydrogen bonded organic framework carrier and the loaded vanadate to preferentially adsorb free water molecules in the aqueous electrolyte, thereby significantly reducing the corrosion activity of water molecules on the positive electrode material, and 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 positive electrode material. The vanadate loaded on the Zn-sulfonated hydrogen bonded organic framework can be slowly released, and the uniform dispersion in the electrolyte is improved. The Zn-sulfonated hydrogen bonded organic framework carrier is also doped with zinc ions, which can cooperate with the strong polarity of the sulfonic acid group, regulate the solvation structure, reduce the interface impedance, and inhibit the growth of zinc dendrites, thereby improving the long-term stability of the aqueous zinc ion battery.

[0019] The addition of basic electrolyte can assist vanadic acid additives, inhibit the growth of positive electrode solvents and zinc dendrites, and help the rapid transport of ions, thereby improving the rate performance of zinc ion batteries.

[0020] 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).

[0021] Preferably, the zinc salt comprises a combination of one or more of zinc nitrate hexahydrate, zinc sulfate heptahydrate and zinc chloride.

[0022] Preferably, the vanadic acid additive is prepared according to the following method: 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; 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.

[0023] Preferably, the organic alcohol includes a combination of one or more of methanol, ethanol and ethylene glycol.

[0024] Preferably, the mass volume ratio of sulfonated terephthalic acid to organic alcohol is 1 g: (30-35) mL.

[0025] 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.

[0026] 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.

[0027] In a second aspect, the present invention provides a method for preparing an aqueous zinc ion battery electrolyte, comprising the following preparation steps: The basic electrolyte is dissolved in deionized water to obtain a premixed solution; the vanadic acid additive is added to the premixed solution, and the mixture is stirred evenly to obtain an aqueous zinc ion battery electrolyte.

[0028] In a third aspect, the present invention provides an application of an aqueous zinc ion battery electrolyte, wherein the electrolyte is applied to a vanadium-based aqueous zinc ion battery; the electrolyte injection process in the vanadium-based aqueous zinc ion battery comprises: S1. The aqueous zinc ion battery electrolyte obtained above is configured to an aqueous electrolyte solution having a viscosity of 8000 to 12000 mPa·s; S2. The electrolyte aqueous solution is coated on the surface of the aqueous diaphragm and dried to obtain a pretreated diaphragm; S3. After the pre-treatment diaphragm, positive electrode sheet and negative electrode sheet are stacked, the aqueous zinc ion battery electrolyte is injected to complete the injection.

[0029] Preferably, in step S2, the aqueous electrolyte solution can be coated on the aqueous diaphragm twice or more to obtain a pretreated diaphragm.

[0030] Preferably, the water-based membrane comprises any one of a glass fiber membrane, a cellulose membrane and a non-woven fabric membrane; the average pore size of the water-based membrane is 2.76 to 3 μm, and the thickness is 200 to 600 μm.

[0031] Preferably, the positive electrode sheet comprises 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 to 50 μm.

[0032] Preferably, the negative electrode sheet is a surface-treated zinc foil, wherein the surface treatment method includes one of polymer coating and roughening treatment.

[0033] By adopting the above technical scheme, the electrolyte added with vanadic acid additive can effectively inhibit the dissolution of the positive electrode, 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 aqueous zinc ion batteries. However, the viscosity of the electrolyte containing vanadic acid additive increases, which increases the difficulty of injection in the process of assembling the battery. Therefore, when the aqueous zinc ion battery electrolyte is used, the present invention also provides a method of injection, which can not only optimize the injection process, but also improve the performance of the aqueous diaphragm, and obtain a zinc ion battery with better performance.

[0034] 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.

[0035] Beneficial effects of the present invention: 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.

[0036] 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

[0037] The present invention will be further described below in conjunction with the accompanying drawings.

[0038] 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; 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 and the high rate (3C) battery long cycle performance test of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Preparation Example

[0041] Preparation Example 1: A vanadic acid additive is prepared according to the following method: 2 mL of ethanol and 1 mL of water were mixed in 8 mL of dimethylformamide, 0.25 mmol of sulfonated terephthalic acid and 0.45 mmol of zinc nitrate hexahydrate were added, and the mixture was stirred at room temperature for 40 min, and then reacted at 120° C. for 24 h. After cooling and crystallization, the Zn-sulfonated hydrogen-bonded organic framework was obtained after washing and drying. 100 mg of sodium vanadate was dissolved in water to prepare a solution with a concentration of 0.1 mol / L, and the pH value of the solution was adjusted to 5. Then, the Zn-sulfonated hydrogen-bonded organic framework obtained above was immersed in the solution and stirred at room temperature for 12 hours to obtain the vanadic acid additive.

[0042] The average loading amount of vanadate on the surface of Zn-sulfonated hydrogen-bonded organic framework is 5wt%.

[0043] Preparation Example 2, a vanadic acid additive, is different from Preparation Example 1 only in that the amount of zinc nitrate hexahydrate added is 0.375 mmol.

[0044] Preparation Example 3, a vanadic acid additive, is different from Preparation Example 1 only in that the amount of zinc nitrate hexahydrate added is 0.5 mmol.

[0045] Preparation Example 4, a vanadic acid additive, is different from Preparation Example 1 only in that the amount of sodium vanadate added 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 %.

[0046] Preparation Example 5, a vanadic acid additive, is different from Preparation Example 1 only in that the amount of sodium vanadate added 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 %.

[0047] Preparation Example 6, a vanadic acid additive, prepared according to the following method: 2 mL of ethanol and 1 mL of water were mixed in 8 mL of dimethylformamide, 0.25 mmol of sulfonated terephthalic acid was added, and the mixture was stirred at room temperature for 40 min, and then reacted at 120° C. for 24 h. After cooling and crystallization, the mixture was washed and dried to obtain a sulfonated hydrogen-bonded organic framework. 100 mg of sodium vanadate was dissolved in water to prepare a solution with a concentration of 0.1 mol / L. The pH value of the solution was adjusted to 5. Then, the sulfonated hydrogen-bonded organic framework obtained above was immersed in the solution and stirred at room temperature for 12 hours to obtain the vanadic acid additive.

[0048] The average loading amount of vanadate on the surface of the sulfonated hydrogen-bonded organic framework is 5 wt %.

[0049] Preparation Example 7, a vanadic acid additive, prepared according to the following method: 2 mL of ethanol and 1 mL of water were mixed in 8 mL of dimethylformamide, 0.25 mmol of terephthalic acid and 0.45 mmol of zinc nitrate hexahydrate were added, and the mixture was stirred at room temperature for 40 min, and then reacted at 120°C for 24 h. After cooling and crystallization, the Zn-hydrogen bond organic framework was obtained after washing and drying. 100 mg of sodium vanadate was dissolved in water to prepare a solution with a concentration of 0.1 mol / L. The pH value of the solution was adjusted to 5. Then the Zn-hydrogen bond organic framework obtained above was immersed in the solution and stirred at room temperature for 12 hours to obtain the vanadic acid additive.

[0050] The average loading amount of vanadate on the surface of Zn-hydrogen bond organic framework is 5wt%.

[0051] Preparation Example 8, a vanadic acid additive, is different from Preparation Example 1 only in that the amount of sodium vanadate added 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 %.

[0052] Preparation Example 9, a vanadic acid additive, is different from Preparation Example 1 only in that the amount of sodium vanadate added 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 %.

[0053] Example

[0054] Embodiment 1, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, are prepared according to the following scheme: 1.5 mol / L zinc trifluoromethanesulfonate and 0.5 mol / L zinc sulfate were dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 was added to the premixed solution, and stirred evenly to obtain an aqueous zinc ion battery electrolyte, wherein the electrolyte contained 7 wt % of the vanadic acid additive, and the viscosity of the electrolyte was 11000 mPa·s.

[0055] The aqueous zinc ion battery electrolyte obtained above is configured into an electrolyte aqueous solution with a viscosity of 9000 mPa·s; the electrolyte aqueous solution is coated on the surface of a glass fiber separator (with an average pore size of 2.76 μm and a thickness of 350 μm), and dried at 60° C. to obtain a pretreated separator; Press the positive electrode (V 2 O 5 / stainless steel foil), pretreated diaphragm, and negative electrode sheet (roughened zinc foil) are stacked in sequence, and then the aqueous zinc ion battery electrolyte obtained above is injected to complete the injection and packaged into a CR2032 button battery.

[0056] Embodiment 2, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, are prepared according to the following scheme: 1 mol / L zinc trifluoromethanesulfonate and 0.5 mol / L zinc sulfate were dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 was added to the premixed solution, and stirred evenly to obtain an aqueous zinc ion battery electrolyte, wherein the electrolyte contained 5 wt % of the vanadic acid additive, and the viscosity of the electrolyte was 10000 mPa·s.

[0057] The aqueous zinc ion battery electrolyte obtained above is configured into an electrolyte aqueous solution with a viscosity of 8000 mPa·s; the electrolyte aqueous solution is coated on the surface of a glass fiber separator (with an average pore size of 2.76 μm and a thickness of 350 μm), and dried at 60° C. to obtain a pretreated separator; Press the positive electrode (V 2 O 5 / stainless steel foil), pretreated diaphragm, and negative electrode sheet (roughened zinc foil) are stacked in sequence, and then the aqueous zinc ion battery electrolyte obtained above is injected to complete the injection and packaged into a CR2032 button battery.

[0058] Embodiment 3, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, are prepared according to the following scheme: 2 mol / L zinc trifluoromethanesulfonate and 0.3 mol / L zinc sulfate were dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 was added to the premixed solution, and stirred evenly to obtain an aqueous zinc ion battery electrolyte, wherein the electrolyte contained 8 wt % of the vanadic acid additive, and the viscosity of the electrolyte was 14000 mPa·s.

[0059] The aqueous zinc ion battery electrolyte obtained above is configured into an electrolyte aqueous solution with a viscosity of 10000 mPa·s; the electrolyte aqueous solution is coated on the surface of a glass fiber separator (with an average pore size of 2.76 μm and a thickness of 350 μm), and dried at 60° C. to obtain a pretreated separator; Press the positive electrode (V 2 O 5 / stainless steel foil), pretreated diaphragm, and negative electrode sheet (roughened zinc foil) are stacked in sequence, and then the aqueous zinc ion battery electrolyte obtained above is injected to complete the injection and packaged into a CR2032 button battery.

[0060] Embodiment 4, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, are prepared according to the following scheme: 1.5 mol / L zinc trifluoromethanesulfonate and 0.5 mol / L zinc sulfate were dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 was added to the premixed solution, and stirred evenly to obtain an aqueous zinc ion battery electrolyte, wherein the electrolyte contained 7 wt % of the vanadic acid additive, and the viscosity of the electrolyte was 11000 mPa·s.

[0061] The aqueous zinc ion battery electrolyte obtained above is configured into an electrolyte aqueous solution with a viscosity of 9000 mPa·s; the electrolyte aqueous solution is coated on the surface of a glass fiber separator (average pore size of 2.76 μm, thickness of 350 μm), pre-dried at 50° C., then coated for a second time, and dried again at 60° C. to obtain a pre-treated separator; Press the positive electrode (V 2 O 5 / stainless steel foil), pretreated diaphragm, and negative electrode sheet (roughened zinc foil) are stacked in sequence, and then the aqueous zinc ion battery electrolyte obtained above is injected to complete the injection and packaged into a CR2032 button battery.

[0062] Example 5, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differs from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 2.

[0063] Example 6, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differs from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 3.

[0064] Example 7, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differs from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 4.

[0065] Example 8, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differs from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 5.

[0066] Comparative Example

[0067] Comparative Example 1, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 6.

[0068] Comparative Example 2, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 7.

[0069] Comparative Example 3, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 8.

[0070] Comparative Example 4, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of the vanadic acid additive prepared in Preparation Example 9.

[0071] Comparative Example 5, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the vanadic acid additive prepared in Preparation Example 1 is replaced by an equal amount of vanadate.

[0072] Comparative Example 6, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the amount of the vanadic acid additive prepared in Preparation Example 1 added to the aqueous zinc ion battery electrolyte is 2 wt %.

[0073] Comparative Example 7, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, differ from Example 1 only in that the amount of the vanadic acid additive prepared in Preparation Example 1 added to the aqueous zinc ion battery electrolyte is 10wt%.

[0074] Comparative Example 8, an aqueous zinc ion battery electrolyte and an aqueous zinc ion battery, are prepared according to the following scheme: 1.5 mol / L zinc trifluoromethanesulfonate and 0.5 mol / L zinc sulfate were dissolved in deionized water to obtain a premixed solution; the vanadic acid additive prepared in Preparation Example 1 was added to the premixed solution, and stirred evenly to obtain an aqueous zinc ion battery electrolyte, wherein the electrolyte contained 7 wt % of the vanadic acid additive, and the viscosity of the electrolyte was 11000 mPa·s.

[0075] Press the positive electrode (V 2 O 5 / stainless steel foil), glass fiber separator (average pore size of 2.76μm, thickness of 350μm), and negative electrode sheet (roughened zinc foil) are stacked in sequence, and the aqueous zinc ion battery electrolyte obtained above is injected by vacuum injection to complete the injection, and the battery is packaged as a CR2032 button battery.

[0076] Performance testing

[0077] 1. Cycle performance test: 10 charge and discharge cycles were performed at a rate of 0.1C and a voltage window of 0.3 to 1.7V to form a uniform SEI film; then, at a rate of 0.5C and a voltage window of 0.3 to 1.7V, the capacity retention rate of the battery samples obtained in the embodiment and the comparative example after 100 cycles was tested.

[0078] 2. High-rate performance test: 10 charge and discharge cycles were performed at a rate of 0.1C and a voltage window of 0.3 to 1.7V to form a uniform SEI film; then, at a rate of 3C and a voltage window of 0.3 to 1.7V, the capacity retention rate of the battery samples obtained in the embodiment and the comparative example after 500 cycles was tested.

[0079] The above test results are shown in Table 1: Table 1 Performance test results

[0080] According to Table 1, in combination with Example 1, Example 4 and Comparative Example 8, it can be seen that the cycle performance and rate performance of Example 4 are increased compared with Example 1, and the cycle performance and rate performance of Comparative Example 8 are decreased compared with Example 1. The reason is that in Example 4, the electrolyte is coated on the surface of the diaphragm in a secondary coating manner, which can make the vanadic acid additive more evenly distributed; in Comparative Example 8, the conventional liquid injection method is used, which not only has a complicated preparation process, but is also not conducive to the uniform distribution of the electrolyte in the positive and negative electrode sheets and the diaphragm, thereby affecting the battery performance.

[0081] Combining Example 1 and Comparative Example 1, it can be seen that the various performances of Comparative Example 1 are reduced compared with those of Example 1. The reason is that the vanadate carrier of the vanadic acid additive in the aqueous zinc ion battery electrolyte obtained in Comparative Example 1 is not doped with zinc ions. On the one hand, the crystal growth process of the carrier lacks the optimization adjustment of zinc ions, which affects the structural stability of the hydrogen-bonded organic framework; on the other hand, the lack of coordination and charge balance of zinc ions is not conducive to the reduction of interfacial impedance, and it is difficult to inhibit the dendrite growth of the zinc negative electrode, thereby affecting the battery performance.

[0082] Combining Example 1 and Comparative Example 2, it can be seen that the various performances of Comparative Example 2 are reduced compared with Example 1. The reason is that the vanadate carrier of the vanadic acid additive in the aqueous zinc ion battery electrolyte obtained in Comparative Example 2 adopts a Zn-hydrogen bond organic framework, and the hydrogen bond organic framework has not been sulfonated, which will reduce the vanadic acid additive's ability to capture free water molecules in the water solvent, reduce the performance of regulating the solubilization structure, increase side reactions, and reduce the ability to inhibit the dissolution of the positive electrode material.

[0083] In combination 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 reduced compared with Example 1. The reason is that the loading amount of vanadate in the vanadic acid additive in Comparative Example 3 and Comparative Example 4 is adjusted out of range, the loading amount of vanadate is reduced, and the ability to change the coordination environment of hydrated zinc ions and adsorb free water molecules is correspondingly reduced, and the electrochemical performance is reduced accordingly; in Comparative Example 4, the loading amount of vanadate is increased, and the active sites on the surface of the carrier 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 cause the activity of the vanadic acid additive to decrease, and the battery performance will decrease.

[0084] Combined with Example 1 and Comparative Example 5, Figure 1 and Figure 2 It can be seen that the performance and specific capacity change trends of Comparative Example 5 are lower than those of Example 1. The reason is that the vanadate added to the aqueous zinc ion battery electrolyte in Comparative Example 5 is not loaded by a carrier, but is directly added to the electrolyte. During the long-term circulation process, the vanadate will accumulate in large quantities, resulting in excessive local concentration, causing precipitation, inducing the occurrence of side reactions, and reducing the stability of the zinc negative electrode, thereby affecting the battery performance.

[0085] In combination with Example 1, Comparative Example 6 and Comparative Example 7, it can be seen that the various performances of Comparative Examples 6 and Comparative Example 7 are reduced compared with Example 1. The reason is that the amount of vanadic acid additive added in the aqueous zinc ion battery electrolyte in Comparative Example 6 is reduced, and the ability to inhibit the dissolution of the positive electrode and stabilize the zinc negative electrode is correspondingly reduced, and the battery performance is reduced; in Comparative Example 7, the amount of vanadic acid additive added in the aqueous zinc ion battery electrolyte is increased, which will cause agglomeration, but is not conducive to the uniform distribution of the vanadic acid additive.

[0086] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0087] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that 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 comprises 5-8 wt% of vanadic acid additive; the vanadic acid additive uses Zn-sulfonated hydrogen bond organic framework as a carrier, and the surface of the carrier is loaded with 4-6 wt% of vanadate.

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

3. The aqueous zinc ion battery electrolyte according to claim 1, characterized in that The raw materials of the Zn-sulfonated hydrogen bond organic framework include sulfonated terephthalic acid and zinc salt in a molar ratio of 1:(1.5-2).

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

5. The aqueous zinc ion battery electrolyte according to claim 3, characterized in that The vanadic acid additive is prepared according to the following method: 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; 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.

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

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

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

9. A method for preparing an aqueous zinc ion battery electrolyte according to any one of claims 1 to 8, characterized in that: The method comprises the following preparation steps: The basic electrolyte is dissolved in deionized water to obtain a premixed solution; the vanadic acid additive is added to the premixed solution, and the mixture is stirred evenly to obtain an aqueous zinc ion battery electrolyte.

10. A use of an aqueous zinc ion battery electrolyte according to any one of claims 1 to 8, characterized in that: The electrolyte is applied to vanadium-based aqueous zinc ion batteries; The electrolyte injection process in the vanadium-based aqueous zinc ion battery comprises: S1. The aqueous zinc ion battery electrolyte according to any one of claims 1 to 8 is configured into an aqueous electrolyte solution having a viscosity of 8000 to 12000 mPa·s; S2. The electrolyte aqueous solution is coated on the surface of the aqueous diaphragm and dried to obtain a pretreated diaphragm; S3. After the pre-treatment diaphragm, positive electrode sheet and negative electrode sheet are stacked, the aqueous zinc ion battery electrolyte is injected to complete the injection.

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