Aqueous zinc ion battery electrolyte containing alkalescent organic compound additive and preparation method and application thereof

Abstract

The invention provides an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive as well as a preparation method and application of the aqueous zinc ion battery electrolyte. Deionized water is used as a solvent, zinc salt is used as an electrolyte, N, N, N ', N'-tetra (2-hydroxypropyl) ethylenediamine is used as an additive, and the concentration is 1g / L. According to the water-based zinc ion battery electrolyte, the alkalescent additive with strong adsorption capacity on the zinc metal surface is introduced into the electrolyte and is used for adjusting the local pH of the zinc negative electrode surface and isolating active water molecules in the electrolyte, so that side reactions related to water are inhibited, uniform deposition of zinc is promoted, and the cycle life of the water-based zinc ion battery is remarkably prolonged. The problems of hydrogen evolution and corrosion caused by thermodynamic instability of a zinc negative electrode in an acidic electrolyte in an existing aqueous zinc ion battery system, the dendritic crystal problem caused by non-uniform deposition of zinc ions, and the problems of short cycle life and low coulombic efficiency of a rechargeable aqueous zinc ion battery are solved.

Description

Technical Field

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

[0002] The continued exploitation and utilization of fossil fuels has exacerbated the energy crisis and global warming, making it increasingly urgent to explore cleaner and more sustainable energy and energy storage technologies. Electrochemical energy storage devices have attracted much attention due to their high efficiency, flexibility and wide application prospects. Among them, the most advanced lithium-ion batteries have been widely used in electric vehicles and portable electronic devices. However, due to the scarcity and high cost of lithium resources, it is necessary to explore alternatives to lithium batteries. In addition, highly active lithium metal and organic flammable electrolytes pose significant safety risks, including fire and explosion, which is not conducive to the development of large-scale energy storage systems with high safety standards. Since the advent of zinc-manganese dioxide batteries equipped with neutral electrolytes in 1986, aqueous zinc-ion batteries have re-emerged in recent years due to their low cost, high safety and environmental protection. However, the difficult-to-control dendrite growth, corrosion and hydrogen evolution problems in the zinc metal anode have hindered the industrial application of aqueous zinc-ion batteries.

[0003] In order to solve the above problems, researchers have proposed a variety of strategies, including current collector design, protective layer coating, diaphragm modification and electrolyte optimization. Among them, electrolyte optimization is considered particularly promising because of its convenience, high efficiency and cost-effectiveness. Generally, the electrolyte used in aqueous zinc-ion batteries is acidic. Due to the strong metallic activity of zinc metal, it exhibits obvious thermodynamic instability in an acidic environment and is prone to hydrogen evolution and corrosion reactions. Appropriate adjustment of the pH of the acidic electrolyte can alleviate the occurrence of such side reactions. However, bulk pH adjustment of the acidic electrolyte often requires the addition of a large amount of alkaline additives, which greatly increases the cost of this electrolyte optimization strategy.

[0004] In addition, high concentrations of additives tend to have a negative impact on ionic conductivity, etc., thus affecting the overall performance of the battery. Therefore, it is not very appropriate to adjust the pH of the electrolyte in the bulk phase, and this problem urgently needs to be studied and solved in depth. It is worth noting that the hydrogen evolution and corrosion reactions on the zinc negative electrode occur between the electrolyte-zinc negative electrode interface. In other words, by adjusting the local pH on the surface of the zinc negative electrode, the hydrogen evolution and corrosion reactions can also be slowed down. Based on this, the present invention has developed a substance with local pH adjustment ability that can solve the side reaction problem on the zinc negative electrode while taking into account the cost. Summary of the invention

[0005] The invention provides an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, a preparation method and an application thereof, and aims to solve the problems of hydrogen evolution and corrosion caused by thermodynamic instability of a zinc negative electrode in an acidic electrolyte, dendrite problems caused by uneven zinc ion deposition, and short cycle life and low coulombic efficiency of a rechargeable aqueous zinc ion battery in an existing aqueous zinc ion battery system.

[0006] In order to achieve the above-mentioned purpose, the embodiments of the present invention provide an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, and a preparation method and application thereof. The present invention uses deionized water as a solvent, a zinc salt as an electrolyte, and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine as an additive, and the concentration of the additive in the electrolyte is 1g / L. The present invention introduces a weakly alkaline additive with strong adsorption force on the surface of zinc metal into the electrolyte, while isolating the active water molecules in the electrolyte while adjusting the local pH of the zinc negative electrode surface. These mechanisms inhibit side reactions related to water, promote the uniform deposition of zinc, and significantly improve the cycle life of aqueous zinc ion batteries.

[0007] The embodiment of the present invention provides an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, wherein the weakly alkaline organic compound additive is N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, and its structural formula is

[0008]

[0009] The aqueous zinc ion battery electrolyte also includes a soluble zinc salt and deionized water.

[0010] Preferably, the concentration of the N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine is 1 g / L.

[0011] Preferably, the soluble zinc salt includes at least one of zinc sulfate, zinc chloride, zinc nitrate and zinc trifluoromethanesulfonate, with a concentration of 0.5 to 4 mol / L, preferably 1 to 3 mol / L, and more preferably 2 mol / L.

[0012] Based on an overall concept of the invention, an embodiment of the present invention provides a method for preparing the above-mentioned aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, weighing a soluble zinc salt and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, adding deionized water, and stirring thoroughly until completely dissolved to prepare the aqueous zinc ion battery electrolyte.

[0013] The embodiments of the present invention also provide a battery comprising the above-mentioned aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive or the aqueous zinc ion battery electrolyte prepared by the above-mentioned preparation method.

[0014] Preferably, the battery is a symmetrical battery composed of commercial zinc foil, glass fiber separator and aqueous zinc ion battery electrolyte.

[0015] Preferably, the battery is a half-cell composed of a commercial stainless steel foil as a positive electrode, a commercial zinc foil as a negative electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

[0016] Preferably, the battery is a half-cell composed of a commercial zinc foil as a negative electrode, a commercial copper foil as a positive electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

[0017] Preferably, the battery is a full battery composed of a commercial zinc foil as a negative electrode, a vanadium-based compound as a positive electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

[0018] Preferably, the vanadium-based compound is ammonium vanadate, which is prepared by a hydrothermal synthesis method.

[0019] The above scheme of the present invention has the following beneficial effects:

[0020] (1) The present invention introduces N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine electrolyte as an additive into the aqueous zinc ion battery electrolyte. Since N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine molecules have a strong adsorption force on the zinc surface, OH can be released. - By adjusting the local pH value on the zinc negative electrode surface, active water molecules are isolated, thereby significantly inhibiting water-related side reactions and guiding the uniform deposition of zinc.

[0021] (2) The aqueous zinc ion battery electrolyte prepared by the present invention is applied to a rechargeable aqueous zinc ion battery, has excellent electrochemical properties, and greatly improves the coulombic efficiency and cycle life of the rechargeable aqueous zinc ion battery.

[0022] (3) The present invention uses N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine as an electrolyte additive, which is non-toxic and safe, low-cost and environmentally friendly. The dosage requirement is small, and the preparation process of the electrolyte is simple, which is suitable for large-scale application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1It is the XRD diagram of the zinc foils of Example 1, Example 2, Example 3, Example 4, Example 5 and Comparative Example 1 of the present invention after being immersed in the electrolyte for 14 days.

[0025] Figure 2 1 is the LSV curve measured by the stainless steel||Zn half-cell assembled with the electrolyte of Example 1 of the present invention and Comparative Example 1.

[0026] Figure 3 It is the XPS spectra of N1s of the zinc foils of Example 1 of the present invention and Comparative Example 1 after being immersed in the electrolyte for 3 days.

[0027] Figure 4 The Zn||Zn symmetric battery of the electrolyte of Example 1 and Comparative Example 1 of the present invention at 1 mA cm -2 and 1mAhcm -2 Cycle performance diagram under conditions of .

[0028] Figure 5 The Zn||Zn symmetric battery of the electrolyte of Comparative Example 2 of the present invention is 1 mA cm -2 and 1mAh cm -2 Cycle performance diagram under conditions of .

[0029] Figure 6 The Zn||Zn symmetric battery of the electrolyte of Example 1 and Comparative Example 1 of the present invention is 0.2 to 10 mA cm -2 Rate performance plot over current density range.

[0030] Figure 7 The Cu||Zn half-cell of the electrolyte of Example 1 of the present invention and Comparative Example 1 is 0.5Acm -2 and 0.5mAhcm -2 Cyclic Coulomb efficiency diagram under the conditions of .

[0031] Figure 8 The NH4V4O of the electrolyte of Example 1 and Comparative Example 1 of the present invention 10 ||Zn full cell in 4Ag -1 Long cycle performance diagram at current density of . DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0033] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0035] Aiming at the problems of hydrogen evolution and corrosion caused by thermodynamic instability of zinc negative electrode in acidic electrolyte, dendrite problem caused by uneven zinc ion deposition, and short cycle life and low coulombic efficiency of rechargeable aqueous zinc ion batteries in existing aqueous zinc ion battery systems, the present invention provides an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, and a preparation method and application thereof.

[0036] The embodiment of the present invention provides an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, wherein the weakly alkaline organic compound additive is N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, and its structural formula is

[0037]

[0038] The aqueous zinc ion battery electrolyte also includes a soluble zinc salt and deionized water.

[0039] Preferably, the concentration of the N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine is 0.1-20 g / L; more preferably, the concentration is 1 g / L.

[0040] Preferably, the soluble zinc salt includes at least one of zinc sulfate, zinc chloride, zinc nitrate and zinc trifluoromethanesulfonate, with a concentration of 0.5 to 4 mol / L, preferably 1 to 3 mol / L, and more preferably 2 mol / L.

[0041] Based on an overall concept of the invention, an embodiment of the present invention provides a method for preparing the above-mentioned aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, weighing a soluble zinc salt and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, adding deionized water, and stirring thoroughly until completely dissolved to prepare the aqueous zinc ion battery electrolyte.

[0042] The embodiments of the present invention also provide a battery comprising the above-mentioned aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive or the aqueous zinc ion battery electrolyte prepared by the above-mentioned preparation method.

[0043] Preferably, the battery is a symmetrical battery composed of commercial zinc foil, glass fiber separator and aqueous zinc ion battery electrolyte.

[0044] Preferably, the battery is a half-cell composed of a commercial stainless steel foil as a positive electrode, a commercial zinc foil as a negative electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

[0045] Preferably, the battery is a half-cell composed of a commercial zinc foil as a negative electrode, a commercial copper foil as a positive electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

[0046] Preferably, the battery is a full battery composed of a commercial zinc foil as a negative electrode, a vanadium-based compound as a positive electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

[0047] Preferably, the vanadium-based compound is ammonium vanadate, which is prepared by a hydrothermal synthesis method.

[0048] The following is a description of the specific embodiments.

[0049] Example 1

[0050] The aqueous zinc ion battery electrolyte in this embodiment contains 2 mol / L ZnSO4 + 1 g / L N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, and its preparation method includes the following steps:

[0051] Step (1): Accurately weigh 57.51 g of zinc sulfate heptahydrate (ZnSO4·7H2O) solid and 0.1 g of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine into a beaker, add 70 mL of deionized water and a stirrer, and stir thoroughly on a magnetic stirrer until completely dissolved for 30 to 60 min.

[0052] Step (2): The solution obtained in step (1) is completely transferred to a 100 mL volumetric flask, deionized water is added to make the volume to 100 mL, and the aqueous zinc ion battery electrolyte described in Example 1 is obtained after being shaken thoroughly.

[0053] Example 2

[0054] Compared with Example 1, the only difference is that the amount of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine added is 0.01 g, and the obtained electrolyte contains 2 mol / LZnSO4+0.1 g / LN,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

[0055] Example 3

[0056] Compared with Example 1, the only difference is that the amount of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine added is 0.5 g, and the obtained electrolyte contains 2 mol / LZnSO4+5 g / LN,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

[0057] Example 4

[0058] Compared with Example 1, the only difference is that the amount of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine added is 1 g, and the obtained electrolyte contains 2 mol / LZnSO4+10 g / LN,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

[0059] Example 5

[0060] Compared with Example 1, the only difference is that the amount of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine added is 2 g, and the obtained electrolyte contains 2 mol / LZnSO4+20 g / LN,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

[0061] Comparative Example 1

[0062] Compared with Example 1, the only difference is that the N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine additive is not added.

[0063] Comparative Example 2

[0064] Compared with Example 1, the only difference is that the additive N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine is replaced by ethylenediaminetetraacetic acid, and the obtained electrolyte contains 2 mol / L ZnSO4 + 1 g / L ethylenediaminetetraacetic acid.

[0065] The aqueous zinc ion battery electrolyte prepared in the above examples and comparative examples is applied to a battery, and the assembled battery comprises the following:

[0066] (1) Zn||Zn symmetric battery:

[0067] The positive and negative electrodes of the Zn||Zn symmetrical battery are made of commercial zinc foil with a diameter of 12 mm and a thickness of 30 microns, and glass fiber is used as a separator between the positive and negative electrodes. The electrolyte configuration can choose the electrolyte of Example 1 or Comparative Example 1. The CR2025 battery shell is used for assembly, and the specific steps include: first install the negative electrode shell, then the negative electrode spring and gasket, then the negative electrode sheet, and then place the glass fiber separator, then inject about 100 microliters of electrolyte, then place the positive electrode sheet, and finally install the positive electrode shell. The entire assembly process is completed in the air, and pressurized packaging is performed after the assembly is completed.

[0068] (2) Stainless steel || Zn half-cell:

[0069] The positive electrode of the stainless steel||Zn half-cell is made of a commercial stainless steel foil with a diameter of 12 mm and a thickness of 30 μm, and the negative electrode is made of a commercial zinc foil with a diameter of 12 mm and a thickness of 30 μm. Glass fiber is used as a separator between the positive and negative electrodes, and the electrolyte is still the electrolyte of Example 1 or Comparative Example 1. The battery assembly method is the same as (1).

[0070] (3) Cu||Zn half-cell:

[0071] The positive electrode of the Cu||Zn half-cell is made of commercial copper foil with a diameter of 12 mm and a thickness of 30 μm, and the negative electrode is made of commercial zinc foil with a diameter of 12 mm and a thickness of 30 μm. Glass fiber is used as a separator between the positive and negative electrodes, and the electrolyte is still the electrolyte of Example 1 or Comparative Example 1. The battery assembly method is the same as (1).

[0072] (4) NH4V4O 10 ||Zn full battery:

[0073] NH4V4O 10 Preparation: 1.17 g of ammonium metavanadate was transferred to a beaker containing 80°C deionized water (50 ml), covered with a plastic wrap with holes and stirred on a magnetic stirrer until the solution turned transparent and light yellow. Then 1.891 g of H2C2O4·H2O was added to the solution and continued to stir until it turned dark blue. The dark blue liquid was transferred to an 80 ml reactor and subjected to a hydrothermal reaction at 140°C for 48 hours. After the reaction, the active NH4V4O was obtained by filtration, washing and drying. 10 Positive electrode material.

[0074] NH4V4O 10 Preparation of positive electrode: First, NH4V4O 10 The positive electrode material, Super-P acetylene black and PVDF were mixed in NMP solvent at a mass ratio of 8:1:1 to obtain a uniform slurry. The obtained slurry was then coated on a stainless steel mesh with a diameter of 12 mm and dried in a vacuum drying oven at 80 °C for 12 h. The mass loading of the positive electrode active material was about 3 mg cm -2 .

[0075] NH4V4O 10 || The positive electrode of the Zn full battery uses the above-mentioned NH4V4O 10 The positive electrode sheet and the negative electrode are made of commercial zinc foil with a diameter of 12 mm and a thickness of 30 μm, and glass fiber is used as a separator between the positive and negative electrodes. The electrolyte is still the electrolyte of Example 1 or Comparative Example 1. The battery assembly method is the same as (1).

[0076] Effect test

[0077] 1. XRD test

[0078] Six pieces of zinc foil with a diameter of 12 mm were immersed in the electrolytes of Example 1, Example 2, Example 3, Example 4, Example 5 and Comparative Example 1 for 14 days, and then taken out and gently rinsed with distilled water and dried in a vacuum environment. The dried zinc foil was tested by XRD (PANalytical / 2Empyrean 2X-ray diffractometer). Figure 1 As shown, characteristic peaks of by-products were observed in the XRD spectra of the zinc foil immersed in the electrolytes of Example 2, Example 3, Example 4, Example 5 and Comparative Example 1, while there were almost no by-products on the surface of the zinc foil immersed in the electrolyte of Example 1, which indicates that the protective effect of local pH adjustment on the surface of the zinc negative electrode using 1g / L N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine is most effective, and the corrosion of the zinc negative electrode is significantly inhibited. Therefore, 1g / L in Example 1 can be selected as the most preferred concentration.

[0079] 2. LSV test

[0080] The stainless steel||Zn half-cell assembled with the electrolytes of Example 1 and Comparative Example 1 was subjected to linear sweep voltammetry (EIS) test on a Shanghai Chenhua CHI660E electrochemical workstation. Figure 2 As shown, the hydrogen evolution overpotential of the zinc metal negative electrode in the electrolyte of Example 1 is greater than that of the electrolyte of Comparative Example 1, indicating that the additive helps to inhibit the hydrogen evolution reaction.

[0081] 3. XPS characterization

[0082] The zinc foil was immersed in the electrolyte of Example 1 and Comparative Example 1 for 3 days, and then gently rinsed with distilled water and dried in a vacuum environment. The dried zinc foil was characterized by X-ray photoelectron spectroscopy (XPS). Figure 3 As shown in the figure, in the electrolyte of Example 1, an obvious N-Zn signal at about 399.5 eV and a NC signal at about 398.3 eV were detected on the zinc surface, which was caused by the adsorption of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine on the zinc surface. In contrast, there was only a weak N-Zn signal on the zinc foil surface in the electrolyte of Comparative Example 1, which may be due to air pollution.

[0083] 4. Electrochemical performance

[0084] The Zn||Zn symmetric cell, Cu||Zn half-cell and NH4V4O were evaluated on a Neware battery test system (CT-4008-5V10mA-164). 10 ||Electrochemical performance of Zn full battery.

[0085] (1) Zn||Zn symmetric battery

[0086] The assembled Zn||Zn symmetric battery was subjected to constant current charge and discharge tests at 30 °C with a current density of 1 mA cm -2 , with a surface capacity of 1 mAh cm -2 .like Figure 4 As shown in the figure, due to the growth of dendrites and the generation of side reactions, the zinc negative electrode using the electrolyte of Comparative Example 1 quickly fails after 50 hours of cycling. However, the cycle life of the battery using the electrolyte of Example 1 exceeds 800 hours. In addition, the cycle performance test of the Zn||Zn symmetric battery using the electrolyte of Comparative Example 2 was also carried out. Figure 5 As shown, although EDTA and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine have very similar molecular structures, the biggest difference is that the four hydroxyl groups are replaced by four carboxyl groups. However, since it itself has four carboxyl groups and is not weakly alkaline, its effect on local pH regulation is minimal. Therefore, the cycle life of the Zn||Zn symmetric battery using the electrolyte of Comparative Example 2 is only about 220 hours.

[0087] The assembled Zn||Zn symmetric battery was tested for rate performance at 30 °C with a current density of 0.2 mA cm -2 ~10mA cm -2 .like Figure 6 As shown in the figure, the battery using the electrolyte of Example 1 exhibits a stronger rate capability, with a current density of 0.2 mA cm -2 Increase to 10 mA cm -2 However, the battery using ZnSO4 electrolyte had a low current density of 2 mA cm -2 A voltage drop occurs when a short circuit occurs.

[0088] (2) Cu||Zn half-cell

[0089] At 0.5 mA cm -2 and 0.5 mAh cm -2 Under the condition of , the assembled Cu||Zn half-cell was subjected to constant current charge and discharge test at 30℃, and the first step was the discharge part. Figure 7 As shown, the average CE value of the Cu||Zn half-cell using the electrolyte of Example 1 within 1100 cycles is 99.15%, while the CE of the half-cell using the electrolyte of Comparative Example 1 fluctuates violently only after 50 cycles and completely fails after 60 cycles.

[0090] (3) NH4V4O 10 ||Zn full battery

[0091] At a current density of 4A -1Under the conditions of 10 ||The Zn full battery was charged and discharged in the voltage range of 0.4V to 1.4V at 30℃. Figure 8 As shown, the NH4V4O electrolyte of Example 1 is used 10 ||Zn full battery at 4A g -1 After 2000 cycles under the condition of -1 The reversible capacity of the battery is 2.37 W, and the capacity retention rate is about 84.2%, while the capacity retention rate of the full battery using the electrolyte of Comparative Example 1 is only 72.1% after 400 cycles.

[0092] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive, characterized in that: The weakly alkaline organic compound additive is N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine; The aqueous zinc ion battery electrolyte also includes a soluble zinc salt and deionized water.

2. The aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive according to claim 1, characterized in that: The concentration of the N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine is 0.1-20 g / L.

3. The aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive according to claim 1, characterized in that: The soluble zinc salt includes at least one of zinc sulfate, zinc chloride, zinc nitrate and zinc trifluoromethanesulfonate, and the concentration is 0.5-4 mol / L.

4. A method for preparing an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive as claimed in any one of claims 1 to 3, characterized in that: Weigh a soluble zinc salt and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, add deionized water, and stir thoroughly until they are completely dissolved to prepare the aqueous zinc ion battery electrolyte.

5. A battery comprising an aqueous zinc ion battery electrolyte containing a weakly alkaline organic compound additive as described in claims 1 to 3 or an aqueous zinc ion battery electrolyte prepared by the preparation method as described in claim 4.

6. The battery according to claim 5, characterized in that The battery is a symmetrical battery composed of commercial zinc foil, glass fiber diaphragm and aqueous zinc ion battery electrolyte.

7. The battery according to claim 5, characterized in that The battery is a half-cell composed of a commercial stainless steel foil as a positive electrode, a commercial zinc foil as a negative electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

8. The battery according to claim 5, characterized in that The battery is a half-cell composed of a commercial zinc foil as a negative electrode, a commercial copper foil as a positive electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

9. The battery according to claim 5, characterized in that The battery is a full battery composed of a commercial zinc foil as a negative electrode, a vanadium-based compound as a positive electrode, a glass fiber separator and an aqueous zinc ion battery electrolyte.

10. The battery according to claim 9, characterized in that The vanadium-based compound is ammonium vanadate, which is prepared by a hydrothermal synthesis method.

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