Aqueous zinc ion battery electrolyte and preparation and application methods thereof

Abstract

The invention relates to the technical field of aqueous energy storage batteries, in particular to an aqueous zinc ion battery electrolyte and preparation and application methods thereof, and the electrolyte comprises a solvent, a zinc salt and an additive; the solvent is deionized water; the additive is prepared by mixing 1, 3, 5-triazine and 1, 3, 5-trioxane according to a molar ratio of (0.15-1): 1; the zinc salt comprises a main salt and a pH buffer salt; the main salt is prepared by mixing zinc sulfate and bis (trifluoromethylsulfonyl) imide zinc according to a molar ratio of (1-4): (1-3); and the pH buffer salt enables the pH value of the electrolyte to be maintained at 4.5-5.5. A proton exchange barrier is formed on an electrode interface, the pH fluctuation of the electrolyte is compressed to a negligible range, and a compound additive of 1, 3, 5-triazine and 1, 3, 5-trioxane is matched for use, so that the growth of zinc dendrites can be remarkably inhibited, the uniformity of zinc deposition can be improved, and meanwhile, the occurrence of interface side reactions can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aqueous energy storage batteries, in particular to an aqueous zinc ion battery electrolyte and a preparation and application method thereof. BACKGROUND

[0002] At present, secondary ion batteries have been widely used in the fields of electronic products and electric vehicles due to their high energy density and long cycle life, and have occupied a dominant position in the commercial market. Although lithium ion batteries have excellent performance, the scarcity of lithium mineral resources and potential safety hazards make it difficult for lithium ion batteries to meet the demand of future market for energy storage batteries.

[0003] In contrast, the rechargeable aqueous zinc ion battery uses a non-flammable water-based electrolyte, so it has higher safety. In addition, among many aqueous metal ion batteries, zinc metal, as a metal with abundant reserves and low price, not only has a high theoretical capacity (820 mAh / g) and a low redox potential (-0.763 V vs SHE), but also zinc element exists in the human body as a trace element, and the compound of zinc is relatively friendly to the environment. Based on these characteristics, aqueous zinc ion batteries have attracted widespread attention. As the core part of zinc ion batteries, the aqueous electrolyte has a crucial influence on the energy storage mechanism and working efficiency of the battery.

[0004] Especially when using zinc metal foil as the negative material of the aqueous zinc ion battery, due to the low surface energy and high migration energy of zinc ions, they cannot be uniformly deposited on the surface of the zinc metal negative electrode, resulting in the growth of dendrites, which may eventually pierce the separator and cause short circuit or capacity reduction. At the same time, the zinc metal negative electrode will inevitably have related side reactions with water molecules, such as corrosion and hydrogen evolution reaction (HER), which will significantly reduce the coulombic efficiency (CE) and cycle stability of the battery. These problems seriously limit the practical application of aqueous zinc ion batteries.

[0005] In order to solve the problems faced by aqueous zinc ion batteries, the current technical route of aqueous zinc ion batteries focuses on alkaline and acidic systems, and the core difference between the two systems lies in the pH regulation and component design of the electrolyte. Among them, the alkaline system uses KOH / ZnO electrolyte, which can inhibit dendrites, but has problems of hydrogen evolution, zinc corrosion and positive electrode dissolution; the acidic system mainly uses zinc sulfate as the main salt to match manganese-based / vanadium-based positive electrodes, but faces the problem of uncontrollable growth of zinc dendrites and electrolyte component hydrolysis / side reactions, which seriously affects the cycle life of the battery. SUMMARY

[0006] The first object of the present application is to provide an aqueous zinc ion battery electrolyte, which synchronously realizes zinc dendrite inhibition and side reaction blocking through the cooperation of zinc salt and additive.

[0007] To achieve the above object, the technical scheme adopted by the present application is:

[0008] A water-based zinc ion battery electrolyte, comprising a solvent, a zinc salt and an additive;

[0009] The solvent is deionized water;

[0010] The additive is prepared by mixing 1,3,5-triazine and 1,3,5-trioxane at a molar ratio of 0.15-1:1;

[0011] The zinc salt comprises a main salt and a pH buffer salt;

[0012] The main salt comprises zinc sulfate and zinc bis(trifluoromethylsulfonyl) imide prepared by mixing at a molar ratio of 1-4:1-3;

[0013] The pH buffer salt is zinc acetate, the concentration of the pH buffer salt is 0.05-0.2 mol / L, the pH value of the electrolyte is maintained at 4.5-5.5, and the acetic acid / zinc acetate forms a buffer pair that can absorb H + The pH fluctuation is controlled within ±0.1, avoiding the uncontrolled hydrolysis of trioxane caused by pH fluctuation and the local over-acid corrosion problem caused by traditional strong acid adjustment.

[0014] The structural formula of the additive is as follows:

[0015]

[0016] The addition of 1,3,5-triazine allows the lone electron (N) to participate in the solvation shell of zinc ions, while reducing the nucleation barrier of zinc ions, which is beneficial to the uniform deposition of zinc ions and inhibits the growth of dendrites, forming a uniform and dense surface, and enhancing the compatibility of the zinc anode / electrolyte interface. 1,3,5-trioxane can undergo ring-opening polymerization on the surface of the zinc metal anode during the cycle process, and react with Zn 2+ to generate the corresponding polymer, and co-precipitate with the reaction products of SO4 2- , Zn 2+ and OH - , and in-situ construct a solid and stable hybrid SEI layer of polymer (ZnPOM)-inorganic (Zn4SO4(OH)6·xH2O) on the zinc metal anode. Thus, the growth of dendrites on the surface of the zinc metal anode and the occurrence of side reactions are inhibited. The cooperation of the two at a molar ratio of 0.15-1:1 ensures that the molecular synergistic effect is maximized, which not only inhibits the longitudinal growth of dendrites, but also significantly reduces the probability of hydrogen evolution and corrosion reactions.

[0017] As preferred, the concentration of the additive is 0.05-1 mol / L, which can fully cover the surface of the zinc negative electrode to form a protective layer, and also avoid the increase of the viscosity and the decrease of the conductivity of the electrolyte caused by excessive addition, the concentration of the zinc salt is 1-3 mol / L, which ensures sufficient supply of zinc ions, so that the battery can still maintain stable deposition / dissolution kinetics at high current density, and at the same time avoids the risk of corrosion of the separator and the electrode material by the over-concentrated electrolyte.

[0018] As preferred, the concentration of 1,3,5-triazine is ≤0.25 mol / L. Avoiding the situation that high concentration of triazine exacerbates local corrosion at zinc foil lattice defects. Make the electrolyte form a more dense protective film on the surface of the zinc foil, significantly improve the cycle stability and interface compatibility of the negative electrode.

[0019] As preferred, a hydrolysis inhibitor is also included, which is any one or more of urea, glycine or inositol hexaphosphate. The mass concentration of the hydrolysis inhibitor is 0.5%-2% of the total mass of the additive. By chemically capturing free formaldehyde or competitively adsorbing on the zinc surface, the hydrolysis path of 1,3,5-triazine in weakly acidic environment is blocked specifically, so that the electrolyte remains stable in composition during long-term cycling.

[0020] In the present application, the electrolyte establishes a dynamic proton exchange balance through zinc acetate in the initial stage, and the H + / OH - is buffered to be absorbed, the interface pH fluctuation is controlled within ±0.1, the trioxane hydrolysis path is blocked from the source, the hydrolysis inhibitor continuously protects during the process, the 1,3,5-trioxane polymer continuously fills the SEI micro-cracks, and the 1,3,5-triazine molecule dynamically adjusts the deposition site to inhibit local electric field concentration. The present application realizes ultra-long life by additive synergy and buffer / inhibitor protection, with CE>99.5% within 500 cycles.

[0021] The second object of the present application is to provide a preparation method of an aqueous zinc ion battery electrolyte, which solves the contradiction between the hydrolysis of 1,3,5-triazine at high temperature and the uneven dispersion of 1,3,5-trioxane at low temperature by controlling the temperature in stages. The introduction of ultrasonic treatment ensures uniform distribution of molecules and avoids performance degradation caused by local aggregation. The stability of the electrolyte components is ensured, and the batch consistency is improved.

[0022] In order to achieve the above object, the technical scheme adopted by the present application is:

[0023] A preparation method of an aqueous zinc ion battery electrolyte, comprising the following steps:

[0024] S1: zinc salt is added to deionized water and stirred until fully dissolved to obtain a basic zinc salt electrolyte,

[0025] S2: 1,3,5-trioxane is added to the base zinc salt electrolyte, and the temperature is raised to 40-45 DEG C, and stirred for 10-15 min;

[0026] S3: the temperature is lowered to 34-36 DEG C, and the hydrolysis inhibitor is added, and stirred for 5-10 min;

[0027] S4: the temperature is lowered to 25-30 DEG C, and 1,3,5-triazine is added, and ultrasonic dispersion is carried out under light shielding conditions; after ultrasonic treatment, vacuum dehydration is carried out, the vacuum degree is less than or equal to -80 kPa, and the time is 5-15 min;

[0028] S5: the pH is adjusted to 4.5-5.5, and the water-based zinc ion battery electrolyte is obtained by filtering and packaging.

[0029] As preferred, in step S4, the ultrasonic treatment is carried out under an inert atmosphere, the ultrasonic power is 200-250 W, and the time is 10-15 min.

[0030] The third object of the present application is to provide an application method of the water-based zinc ion battery electrolyte, in the application scenario of the metal zinc foil negative electrode, the two-dimensional dendrite growth and the grain boundary corrosion of the zinc foil are significantly inhibited through the optimized additive concentration and the inhibitor selection.

[0031] In order to achieve the above object, the technical scheme adopted by the present application is:

[0032] The application of the water-based zinc ion battery electrolyte in the water-based zinc ion battery includes that the electrolyte is used for assembling the water-based zinc ion battery, and the water-based zinc ion battery includes a positive electrode, a negative electrode, a separator, a gasket, a spring and the electrolyte. Specifically, the assembly is carried out in the order of negative electrode shell, negative electrode, separator, electrolyte, positive electrode, gasket, spring and positive electrode shell, and the water-based zinc ion battery is obtained. Alternatively, the assembly is carried out in the order of positive electrode shell, positive electrode, separator, electrolyte, negative electrode, gasket, spring and negative electrode shell.

[0033] As preferred, when the battery is assembled, the pressure is increased to 8-12 MPa, and the pressure is maintained for 30-60 s.

[0034] As preferred, the negative electrode is a metal zinc foil, and the assembly is carried out in the order of negative electrode shell, negative electrode, separator, electrolyte, positive electrode, gasket, spring and positive electrode shell, so that the pre-passivation layer formed by the delayed contact between the zinc foil and the electrolyte is reduced.

[0035] The positive electrode includes a current collector, a positive electrode material, conductive carbon black and a binder, the positive electrode material, the conductive carbon black and the binder are uniformly mixed, then the obtained slurry is uniformly coated on the current collector, and after completion, drying is carried out to obtain the positive electrode.

[0036] The mass ratio of the positive material, conductive carbon black and binder is 70-80:10-20:10; the positive material is at least one of vanadium pentoxide and sodium vanadate, the binder is polyvinylidene fluoride, and the coating thickness of the slurry is 100-200 mu m. The drying temperature is 50-100 DEG C, and the time is 8-24 h. The thickness of the zinc sheet negative electrode is 50 mu m; and the material of the diaphragm is glass fiber.

[0037] Preferably, the current collector is titanium foil, and the diaphragm is glass fiber diaphragm.

[0038] The beneficial effects of the present application are:

[0039] The present application can significantly inhibit the growth of zinc dendrites, improve the uniformity of zinc deposition, and effectively reduce the occurrence of interface side reactions by using 1,3,5-triazine and 1,3,5-trioxane complex additives. By introducing pH buffer salt to form a proton exchange barrier at the electrode interface, the pH fluctuation of the electrolyte is compressed to a negligible range; the nitrogen heterocyclic structure in the triazine molecule can be preferentially adsorbed on the high activity site of the zinc negative electrode surface, and the deposition behavior of zinc ions can be regulated to grow along the flat crystal surface, thereby avoiding the generation and spread of dendrites. Trioxane forms a dynamic protective layer in the electrolyte through its unique ring structure, blocking the direct contact of water molecules with zinc metal, and significantly reducing the occurrence of hydrogen evolution and corrosion reactions. The synergistic effect of the two additives makes the zinc ions maintain high reversibility during the deposition / dissolution process, significantly improving the cycle stability of the battery.

[0040] Reference signs

[0041] Figure 1 The cycle performance comparison chart of the aqueous zinc ion full battery assembled for example 1 and comparative example 1 of the present application;

[0042] Figure 2 The SEM images of the zinc electrode surface after the Zn||Zn symmetric battery using the electrolyte of example 2 and comparative example 2 is cycled at a current density of 2 mA / cm 2 and a deposition capacity of 2 mAh / cm 2 .

[0043] Figure 3 The cycle performance chart of the Zn||Zn symmetric battery using the electrolyte of example 2 and comparative example 2 at a current density of 2 mA / cm 2 and a deposition capacity of 2 mAh / cm 2 . DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] The raw materials or reagents used in the examples and / or comparative examples of the present application are purchased from mainstream manufacturers in the market. If the manufacturer is not specified or the concentration is not specified, it is an analytical pure raw material or reagent that can be obtained conventionally, and there is no particular limitation as long as it can play the expected role. The instruments and equipment used in the examples are purchased from major manufacturers in the market, and there is no particular limitation as long as they can play the expected role. If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction.

[0047] Example 1

[0048] (I) Preparation method of aqueous zinc ion battery electrolyte

[0049] An aqueous zinc ion battery electrolyte comprises:

[0050] Deionized water;

[0051] An additive comprising 1,3,5-triazine 0.20 mol / L and 1,3,5-trioxane 0.48 mol / L;

[0052] A zinc salt comprising zinc sulfate 1.4 mol / L, bis(trifluoromethylsulfonyl) imidazole zinc 1.0 mol / L; zinc acetate 0.1 mol / L;

[0053] Further comprising 1.8% of the total mass of the additive urea.

[0054] A preparation method of an aqueous zinc ion battery electrolyte comprises the following steps:

[0055] S1: zinc salt is added to deionized water and stirred until fully dissolved to obtain a basic zinc salt electrolyte,

[0056] S2: 1,3,5-trioxane is added to the basic zinc salt electrolyte, heated to 42℃, and stirred for 12 min;

[0057] S3: cool to 35℃, add urea, and stir for 8 min;

[0058] S4: cool to 28℃, add 1,3,5-triazine, and ultrasonically disperse for 10 min under light shielding conditions, and then vacuum dehydrate;

[0059] S5: adjust the pH to 4.5-5.5, filter and package to obtain the aqueous zinc ion battery electrolyte.

[0060] (II) Preparation method of battery positive electrode, negative electrode and separator

[0061] (1) Preparation of positive electrode sheet: Sodium vanadate (NVO) positive electrode preparation: 5.0 grams of V2O5 powder was mixed with 50 milliliters of 2M sodium chloride aqueous solution. The mixed solution was stirred at 25°C for 3 days (the color of the solution changed from orange to red-orange). After the reaction, the mixed solution was centrifuged and washed with deionized water and ethanol several times, and then dried at 70°C for 24 hours. Finally, red-orange NVO nanofiber powder was collected. The NVO nanofiber powder, conductive carbon black and polyvinylidene fluoride were mixed in a weight ratio of 7:2:1 in N-methylpyrrolidone to form a slurry, coated on a Ti foil, and then dried in a vacuum oven at 80°C for standby, the mass loading of NVO on the electrode was 1-2 mg / cm 2 .

[0062] (2) Preparation of negative electrode sheet: High-purity zinc foil (99.99%) with a thickness of 0.05 mm was cut into a circular sheet with a diameter of 12 mm, placed in a beaker containing absolute ethanol, ultrasonically treated in an ultrasonic cleaner for 10 minutes, and then dried in a blast drier for 30 minutes, and taken out for standby.

[0063] (3) Preparation of separator: The glass fiber separator was cut into a circular sheet with a diameter of 19 mm.

[0064] (III) Battery assembly

[0065] Assembled in the order of positive electrode shell, positive electrode sheet, separator, electrolyte, negative electrode sheet, gasket, spring, and negative electrode shell, and the battery was compacted with a tablet press.

[0066] Comparative Example 1: The remaining components and preparation methods are the same as those of Example 1, except that no additives are added to the electrolyte.

[0067] Characterization and testing

[0068] The full battery prepared in this example was subjected to long cycle performance test at a current density of 5 A / g, Figure 1 is the corresponding long cycle performance curve. As can be seen from the figure, the capacity retention rate of the battery is higher than 90% and the coulombic efficiency is greater than 99% after 2000 cycles. The control sample is Comparative Example 1, and the cycle performance curve is discharged at a current density of 5 A / g. The capacity retention rate of the battery is only 50% after 2000 cycles. It shows that the hydrolysis inhibitor and the additive can synergistically inhibit the side reaction, and the pH buffer salt can also maintain the non-hydrolysis of trioxane, avoid the corrosion of formaldehyde to the positive electrode, and ensure the long cycle stability.

[0069] Example 2

[0070] Preparation method of aqueous zinc ion battery electrolyte

[0071] An aqueous zinc ion battery electrolyte, comprising:

[0072] Deionized water;

[0073] An additive, comprising 1,3,5-triazine 0.08 mol / L and 1,3,5-trioxane 0.32 mol / L;

[0074] A zinc salt, comprising zinc sulfate 1.6 mol / L, bis(trifluoromethylsulfonyl) imidazole zinc 0.4 mol / L; zinc acetate 0.1 mol / L;

[0075] Further comprising 1.5% of the total mass of the additive glycine.

[0076] A preparation method of an aqueous zinc ion battery electrolyte, comprising the following steps:

[0077] S1: Add zinc salt to deionized water and stir until fully dissolved to obtain a basic zinc salt electrolyte,

[0078] S2: Add 1,3,5-trioxane to the basic zinc salt electrolyte, heat to 45℃, and stir for 10 min;

[0079] S3: Cool to 35℃, add glycine, and stir for 8 min;

[0080] S4: Cool to 30℃, add 1,3,5-triazine, and ultrasonically disperse under light-free conditions for 10 min at 220W, then vacuum dehydrate;

[0081] S5: Adjust the pH to 4.5-5.5, filter and package to obtain the aqueous zinc ion battery electrolyte.

[0082] (ii) Preparation method of battery positive and negative electrodes

[0083] Preparation of positive and negative electrode sheets: high-purity zinc foil (99.99%) with a thickness of 0.05 mm is cut into a rectangular sheet with a length of 1.5 cm and a width of 1 cm, placed in a beaker containing anhydrous ethanol, ultrasonically treated in an ultrasonic cleaner for 10 minutes, then dried in a forced air dryer for 30 minutes, and taken out for standby.

[0084] (iii) Battery assembly

[0085] Assemble the symmetrical battery according to the positive electrode shell, zinc foil, separator, electrolyte, zinc foil, gasket, spring, and negative electrode shell.

[0086] Comparative Example 2: Except that the electrolyte does not add an additive, the remaining components and preparation method are the same as Example 2.

[0087] Characterization and testing

[0088] The symmetric battery prepared in this example was cycled at a current density of 2 mA / cm 2 and an area capacity of 2 mAh / cm 2 After 50 cycles, Figure 2 a is the SEM picture of the zinc negative electrode surface after 50 cycles of the symmetric battery using Example 2, it can be seen that a uniform passivation film is formed on the surface of the zinc negative electrode, and no dendrite is generated on the surface. In contrast, Figure 2 b is the SEM picture of the zinc negative electrode surface after 50 cycles of the symmetric battery using Comparative Example 2, it can be seen that the zinc negative electrode surface after cycling shows a rough surface of zinc dendrites. Figure 3 is the charge-discharge performance diagram of the symmetric battery at a current density of 2 mA / cm 2 and an area capacity of 2 mAh / cm 2 The cycle life of the battery after adding the additive reached 1400h, which is much higher than 130h of Comparative Example 2. This shows that the addition of the additive can improve the cycle stability of the battery.

[0089] Examples 3-7

[0090] (I) Preparation method of aqueous zinc ion battery electrolyte

[0091] An aqueous zinc ion battery electrolyte comprises:

[0092] Deionized water;

[0093] An additive comprising 1,3,5-triazine and 1,3,5-trioxane mixed at a molar ratio of 0.15-1:1; the concentration of the additive is 0.05-1 mol / L,

[0094] A zinc salt, the concentration of the zinc salt is 1-3 mol / L, comprising a main salt and a pH buffer salt, the main salt comprises zinc sulfate and bis(trifluoromethylsulfonyl) imidazole zinc mixed at a molar ratio of 1-4:1-3, and the pH buffer salt is zinc acetate, the concentration is 0.05-0.2 mol / L;

[0095] Further comprising 0.5%-2.5% of glycine based on the total mass of the additive.

[0096] A preparation method of an aqueous zinc ion battery electrolyte comprises the following steps:

[0097] S1: Add zinc salt to deionized water and stir until fully dissolved to obtain a basic zinc salt electrolyte,

[0098] S2: Add 1,3,5-trioxane to the basic zinc salt electrolyte, heat to 45°C, and stir for 10 min;

[0099] S3: cool down to 35℃, add glycine, stir for 8 min;

[0100] S4: cool down to 30℃, add 1,3,5-triazine, ultrasonic dispersion under light-proof condition for 10 min at 220W, then vacuum dehydration;

[0101] S5: adjust pH to 4.5-5.5, filter and package to obtain water-based zinc ion battery electrolyte.

[0102] The specific dosage is shown in the following table:

[0103] Group ZnSO4 Zn(TFSI)2 Zinc acetate Triazine Trioxane Glycine Example 3 1.8 0.7 0.10 0.10 0.40 1.5％ Example 4 1.4 0.6 0.10 0.12 0.48 2.0％ Example 5 1.0 0.5 0.20 0.25 0.60 1.8％ Example 6 2.0 1.0 0.05 0.06 0.24 2.5％ Example 7 1.0 1.0 0.15 0.25 0.25 2.0％

[0104] (B) Preparation method of battery positive and negative electrodes

[0105] (1) Preparation of positive electrode sheet: high-purity copper foil (99.99%) with a thickness of 0.02 mm was cut into a circular sheet with a diameter of 12 mm, placed in a beaker containing anhydrous ethanol, ultrasonically treated in an ultrasonic cleaner for 10 minutes, then dried in a forced air dryer for 30 minutes, and taken out for standby.

[0106] (2) Preparation of negative electrode sheet: high-purity zinc foil (99.99%) with a thickness of 0.05 mm was cut into a circular sheet with a diameter of 12 mm, placed in a beaker containing anhydrous ethanol, ultrasonically treated in an ultrasonic cleaner for 10 minutes, then dried in a forced air dryer for 30 minutes, and taken out for standby.

[0107] (Four) Assembly of Zn||Cu half-cell

[0108] According to the positive electrode shell, copper foil, separator, electrolyte, zinc foil, gasket, spring, and negative electrode shell, the zinc-copper asymmetric battery was assembled.

[0109] Characterization and testing

[0110] The Zn||Cu half-cell prepared in this example was cycled at a current density of 2 mA / cm 2 and an area capacity of 2 mAh / cm 2 The specific data are shown in the following table:

[0111]

[0112] As shown above, it can be known that the cycle life of the optimal embodiment 4 reaches 680 times, in the embodiments 5 and 7, the 1,3,5-triazine 0.25 mol / L, there is a trace of phosphate deposition, in the embodiment 6, the buffer salt content is at the lower limit, after multiple cycles, because of the pH fluctuation, the deposition is uneven, which illustrates the necessity of maintaining the pH value of the electrolyte at 4.5-5.5 and controlling the concentration of 1,3,5-triazine ≤0.25 mol / L. The triazine concentration can be significantly avoided to be too high to exacerbate the local corrosion at the zinc foil lattice defect. The electrolyte can form a more dense protective film on the zinc foil surface, and the cycle stability and interface compatibility of the negative electrode are improved.

[0113] Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope 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 the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. An aqueous zinc ion battery electrolyte, characterized in that including solvents, zinc salts and additives; The solvent is deionized water; The additive is prepared by mixing 1,3,5-triazine and 1,3,5-trioxane in a molar ratio of 0.15 to 1:1; The zinc salt includes a main salt and a pH buffer salt; The main salt comprises zinc sulfate and bis(trifluoromethanesulfonyl)imide zinc, which are mixed in a molar ratio of 1-4:1-3; the pH buffer salt maintains the pH value of the electrolyte at 4.5-5.

5.

2. An aqueous zinc ion battery electrolyte according to claim 1, characterized in that The concentration of the additive is 0.05-1 mol / L, the concentration of the zinc salt is 1-3 mol / L, the pH buffer salt is zinc acetate, and the concentration of the pH buffer salt is 0.05-0.2 mol / L.

3. An aqueous zinc ion battery electrolyte according to claim 1, characterized in that The concentration of the 1,3,5-triazine is ≤0.25 mol / L.

4. An aqueous zinc ion battery electrolyte according to any one of claims 1 to 3, characterized in that It also includes a hydrolysis inhibitor, wherein the mass concentration of the hydrolysis inhibitor is 0.5% to 2.5% of the total mass of the additive.

5. An aqueous zinc ion battery electrolyte according to claim 4, characterized in that, The hydrolysis inhibitor is any one or more of urea, glycine or phytic acid.

6. The method for preparing an aqueous zinc ion battery electrolyte according to claim 5, wherein: The steps include: S1: Add zinc salt to deionized water and stir until fully dissolved to obtain a basic zinc salt electrolyte. S2: Add 1,3,5-trioxane to the basic zinc salt electrolyte, heat to 40-45°C, and stir for 10-15 minutes; S3: Cool to 34-36°C, add hydrolysis inhibitor, and stir for 5-10 minutes; S4: Cool to 25-30°C, add 1,3,5-triazine, and disperse by ultrasonication in the dark. S5: adjusting the pH to 4.5-5.5, filtering and encapsulating to obtain an aqueous zinc ion battery electrolyte.

7. The method for preparing an aqueous zinc ion battery electrolyte according to claim 6, wherein: In step S4, after the ultrasonic treatment, vacuum dehydration is performed with a vacuum degree of ≤-80 kPa for 5 to 15 minutes.

8. The method for preparing an aqueous zinc ion battery electrolyte according to claim 6, wherein: In step S4, ultrasonic treatment is performed under an inert atmosphere with an ultrasonic power of 200-250 W and a time of 10-15 min.

9. Use of the aqueous zinc ion battery electrolyte according to claim 1 in an aqueous zinc ion battery, characterized in that: The application includes using the electrolyte to assemble an aqueous zinc ion battery, wherein the aqueous zinc ion battery includes a positive electrode, a negative electrode, a separator and the electrolyte.

10. The application method of an aqueous zinc ion battery electrolyte according to claim 9, characterized in that: When assembling the battery, pressurize it to 8-12 MPa and maintain the pressure for 30-60 seconds.

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