Aqueous zinc ion electrolyte based on trace additive as well as preparation method and application of aqueous zinc ion electrolyte

Abstract

The invention provides an aqueous zinc ion electrolyte based on a trace additive and a preparation method and application of the aqueous zinc ion electrolyte, and the method comprises the step of mixing 1-500 mg / L of a pyridine azo compound, 0.5-5 mol / L of zinc salt and deionized water according to the volume ratio of 1: (35000-36000): (123000-125000) to obtain the aqueous zinc ion electrolyte. The specific additive is added into the zinc salt, the additive has azo, pyridine nitrogen, benzene ring and other groups and can be parallelly and automatically adsorbed on the surface of zinc metal, and tiled macromolecules are utilized to efficiently extrude water molecules at a zinc interface; and the molecules of the additive have strong pi-pi interaction, so that a compact accumulation layer can be formed, the accumulation density of the additive on the surface of the zinc metal negative electrode is effectively improved, the utilization rate of the additive is increased, the dosage of the additive is reduced, and meanwhile, the advantages of high ionic conductivity, high safety and low cost of the aqueous zinc ion battery are reserved.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc ion electrolytes, and in particular to an aqueous zinc ion electrolyte based on trace additives, a preparation method thereof, and an application thereof. Background Art

[0002] With the wide application of solar energy and wind energy, energy storage technologies for storing this intermittent renewable energy have attracted the attention of many people. Lithium-ion batteries are the most widely used battery technologies at present. However, problems such as the scarcity of lithium resources and the flammability of organic electrolytes have prevented their application in large-scale energy storage systems. Aqueous zinc ion batteries are considered to be one of the strong candidates for large-scale energy storage systems due to their inherent safety, low cost, and high specific capacity. However, problems such as uncontrollable dendrite growth, hydrogen evolution, and corrosion on the surface of the zinc anode have greatly shortened the cycle life of the battery and seriously hindered the practical application of zinc ion batteries.

[0003] To address the above problems, currently, various strategies such as electrode surface engineering, separator improvement, electrode structure design, and electrolyte optimization can be used to improve the electrochemical stability of the zinc anode. Among them, the electrolyte additive strategy has the advantages of simple preparation, low cost, and remarkable effect, and is considered to be the most direct and effective method. The introduced additives can change the Zn2+ solvation structure, preferentially adsorb on the surface of the zinc anode over water molecules, effectively isolate the active water molecules in the electrolyte from contacting the zinc metal, and reduce the occurrence of side reactions. And the adsorbed additives can also homogenize the zinc ion flux, promote the uniform deposition of metallic zinc, and inhibit the growth of zinc dendrites. The introduction of additives can significantly improve the electrochemical stability of zinc ion batteries.

[0004] However, the amount of currently known additives is much higher than the actual required amount. Taking the CR 2032 button battery as an example, a single battery usually adds 100ul–200ul of electrolyte, while the surface area of the used zinc anode (with a diameter of 12mm) is only 1.13cm2, and the surface zinc atoms are approximately 2.034×10-9mol. It is equivalent that the total concentration of additives required in 100ul of electrolyte is 0.01mM, and the dosage of additives used in most current literatures is about 50-500mM. The excessive dosage of additives often brings higher costs and also loses the advantages of high ionic conductivity and high safety of aqueous electrolytes. Therefore, there is an urgent need to develop efficient aqueous electrolyte additives to improve the stability of the zinc anode while maintaining the advantages of aqueous batteries themselves. Summary of the Invention

[0005] The purpose of the present invention is to provide an aqueous zinc ion electrolyte based on trace additives, a preparation method thereof, and an application thereof, aiming to solve the problems that the excessive dosage of additives in traditional technologies will bring higher costs and also lose the high ionic conductivity and high safety of aqueous electrolytes.

[0006] In a first aspect, the present invention provides a method for preparing an aqueous zinc ion electrolyte based on a trace additive, and the preparation method includes:

[0007] Mix a pyridine azo compound at 1 - 500 mg / L, a zinc salt at 0.5 - 5 mol / L, and deionized water in a volume ratio of 1:35000 - 36000:123000 - 125000 to obtain an aqueous zinc ion electrolyte.

[0008] In summary, according to the above - mentioned method for preparing an aqueous zinc ion electrolyte based on a trace additive, by adding a specific additive to a zinc salt and at a specific concentration ratio, an efficient aqueous electrolyte is obtained. This additive has groups such as azo, pyridine nitrogen, and benzene ring, and can self - adsorb parallelly on the zinc metal surface, using the flat macromolecules to efficiently extrude water molecules at the zinc interface; and there is a strong π - π interaction between additive molecules, which can form a dense stacking layer, effectively improving the stacking density of the additive at the zinc metal negative electrode surface, increasing the utilization rate of the additive and reducing the dosage of the additive. In addition, the polar functional groups such as azo and pyridine nitrogen contained in the efficient additive can chelate with zinc ions, uniform the zinc ion flow, and promote the uniform deposition of zinc. In addition, only a trace amount of additive needs to be added to significantly improve the interfacial stability of the zinc negative electrode, improve the cycle stability of the zinc ion battery, while retaining the advantages of high ionic conductivity, high safety, and low cost of the aqueous zinc ion battery. And the efficient additive is low - cost and has a simple preparation process, which is conducive to large - area industrial production.

[0009] Further, the pyridine azo compound includes at least one of the groups of pyridine nitrogen, azo, and phenolic hydroxyl.

[0010] Further, the pyridine azo compound includes at least one of 2 - (5 - nitro - 2 - pyridylazo)resorcinol, 2 - (5 - bromo - 2 - pyridylazo)-5 - diethylaminophenol, 1 - (2 - pyridylazo)-2 - naphthol, 2 - (2 - pyridylazo)-1 - naphthol, 4 - 2 - pyridylazo - N,N - dimethylaniline, 4 - (2 - pyridylazo)resorcinol, 4 - (5 - chloro - 2 - pyridylazo)-1,3 - phenylenediamine, 4 - (3,5 - dibromo - 2 - pyridylazo)-1,3 - phenylenediamine, 2 - (2 - pyridylazo)-5 - dimethylaminophenol.

[0011] Further, the zinc salt includes at least one of zinc sulfate heptahydrate, zinc trifluoromethanesulfonate, zinc chloride, and zinc perchlorate hexahydrate.

[0012] Further, the volume ratio of the pyridine azo compound, the zinc salt, and deionized water is 1:35650:124000.

[0013] Second aspect, the present invention provides an aqueous zinc ion electrolyte prepared by the preparation method of the above-mentioned aqueous zinc ion electrolyte based on trace additives.

[0014] Third aspect, the present invention provides an application of the above-mentioned aqueous zinc ion electrolyte in a zinc-zinc symmetric battery, characterized in that the application includes:

[0015] Using zinc metal as the positive and negative electrodes, separating the positive and negative electrodes with a separator, and using the aqueous zinc ion electrolyte as the electrolyte to assemble a zinc-zinc symmetric battery.

[0016] Fourth aspect, the present invention provides an application of the above-mentioned aqueous zinc ion electrolyte in a zinc-copper half-cell, characterized in that the application includes:

[0017] Using zinc metal as the negative electrode and copper metal as the positive electrode, separating the positive and negative electrodes with a separator, and using the aqueous zinc ion electrolyte as the electrolyte to assemble a zinc-copper half-cell.

[0018] Fifth aspect, the present invention provides an application of the above-mentioned aqueous zinc ion electrolyte in a full cell, characterized in that the application includes:

[0019] Using zinc metal as the negative electrode and the active material as the positive electrode, separating the positive and negative electrodes with a separator, dropping the prepared electrolyte on the separator, and assembling it into a full cell;

[0020] In some embodiments, the active material at least includes one of ammonium vanadate, manganese dioxide, iodine, polyaniline, vanadium pentoxide, sulfur.

[0021] In some embodiments, the zinc metal includes zinc sheets, zinc foils, zinc powders, and zinc foams.

[0022] In some embodiments, the separator includes glass fiber, filter paper, or aqueous filter membrane.

[0023] In some embodiments, the copper metal includes copper sheets, copper foils, copper powders, and copper foams.

[0024] In some embodiments, the preparation method of the positive electrode is: pressing and cutting ammonium vanadate, manganese dioxide, iodine, polyaniline, vanadium pentoxide, or sulfur positive electrode.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The present invention proposes an aqueous zinc ion electrolyte with simple process and low cost. The additive used in the aqueous zinc ion electrolyte can self-adsorb on the surface of zinc metal, uniform the zinc ion flow and effectively inhibit HER. At 2 mA cm -2 , 1 mAh cm-2 Under such circumstances, the zinc-zinc symmetric battery composed of the electrolyte configured with this trace electrolyte additive can stably cycle for more than 1500 h. The full battery paired with ammonium vanadate achieves a discharge specific capacity of 235 mAh g -1 in the first cycle, and the capacity retention rate is about 70% after 1300 cycles; this work provides a new solution for the practical application of zinc metal anodes. -1

[0027] 2. The principle of the present invention is as follows: The present invention uses a compound containing pyridine nitrogen, azo, and benzene ring as an additive. The N atom therein has a lone pair of electrons, which can self-adsorb on the zinc metal surface, homogenize the zinc ion flow, and reduce the occurrence of HER. The aqueous zinc ion electrolyte prepared by the present invention only needs to add a small amount of pyridine azo-based compound, which reduces the production cost and does not require heating and stirring, and the preparation process is simple. Description of the Drawings

[0028] Figure 1 It is a schematic diagram comparing the adsorption energy and differential charge density of different configurations of 1-(2-pyridylazo)-2-naphthol and water on the zinc surface;

[0029] Figure 2 It is a schematic diagram of the molecular dynamics simulation of the self-adsorption process of 1-(2-pyridylazo)-2-naphthol;

[0030] Figure 3 It is the Tafel diagram of Example 1 and Comparative Example 1 of the present invention;

[0031] Figure 4 It is the XRD diagram of metallic zinc immersed in Example 1 and Comparative Example 1 of the present invention;

[0032] Figure 5 It is a schematic diagram of the interaction energy between different configurations of 1-(2-pyridylazo)-2-naphthol, water, zinc ions, and 1-(2-pyridylazo)-2-naphthol;

[0033] Figure 6 It is a schematic diagram of the color change of Example 2 and Comparative Example 2;

[0034] Figure 7 It is the UV-vis diagram of Example 2 and Comparative Example 2;

[0035] Figure 8 It is a schematic diagram of the nucleation overpotential of the zinc-copper half-cell assembled with Example 1 and Comparative Example 1;

[0036] Figure 9 It is a schematic diagram of the CA curve of the zinc-zinc symmetric battery assembled with Example 1 and Comparative Example 1;

[0037] Figure 10 ​is a schematic diagram of ionic conductivity of Example 1 and Comparative Example 1;

[0038] Figure 11 is a schematic diagram of in-situ optical testing of Example 1 and Comparative Example 1;

[0039] Figure 12 Schematic diagram of COMSOL multi-physics simulation of Example 1 and Comparative Example 1;

[0040] Figure 13 The zinc-zinc symmetric battery assembled by Example 1 and Comparative Example 1 was used at 2 mA cm –2 @1mAh cm –2 Performance comparison chart under different conditions;

[0041] Figure 14 The zinc-copper half-cells assembled using Example 1 and Comparative Example 1 were tested at 5 mA cm –2 @1mAh cm –2 Performance comparison chart under different conditions;

[0042] Figure 15 The zinc-ammonium vanadate full battery assembled using Example 1 and Comparative Example 1 was used at 1Ag -1 Performance comparison chart under different conditions.

[0043] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are 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. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0045] Example 1

[0046] 10 μL of 20 mg / L 1-(2-pyridyl azo)-2-naphthol was dissolved in 1.24 L of deionized water, and after thorough mixing, 0.355 L of 2 mol / L zinc sulfate heptahydrate was added to obtain an aqueous zinc ion electrolyte.

[0047] Example 2

[0048] Dissolve 10 μL of 1-(2-pyridylazo)-2-naphthol at 20 mg / L in 1.23 L of deionized water. After thorough mixing, add 0.35 L of zinc sulfate heptahydrate at 2 mol / L to obtain an aqueous zinc ion electrolyte solution.

[0049] Example 3

[0050] Dissolve 10 μL of 1-(2-pyridylazo)-2-naphthol at 20 mg / L in 1.25 L of deionized water. After thorough mixing, add 0.36 L of zinc sulfate heptahydrate at 2 mol / L to obtain an aqueous zinc ion electrolyte solution.

[0051] Examples 4 - 11

[0052] Examples 4 - 11 are basically the same as Example 1, except that 1-(2-pyridylazo)-2-naphthol is adjusted to 2-(5-nitro-2-pyridylazo)resorcinol, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, 2-(2-pyridylazo)-1-naphthol, 4-(2-pyridylazo)-N,N-dimethylaniline, 4-(2-pyridylazo)resorcinol, 4-(5-chloro-2-pyridylazo)-1,3-phenylenediamine, 4-(3,5-dibromo-2-pyridylazo)-1,3-phenylenediamine, 2-(2-pyridylazo)-5-dimethylaminophenol.

[0053] Comparative Example 1

[0054] Dissolve 0.355 L of zinc sulfate heptahydrate at 2 mol / L in 1.24 L of deionized water to obtain an aqueous zinc ion electrolyte solution.

[0055] Comparative Example 2

[0056] Dissolve 10 μL of 1-(2-pyridylazo)-2-naphthol at 20 mg / L in 1.24 L of deionized water to obtain an aqueous zinc ion electrolyte solution.

[0057] Comparative Example 3

[0058] Dissolve 10 μL of 5-dimethylamino-2-(2-pyridylazo)phenol at 20 mg / L in 1.24 L of deionized water. After thorough mixing, add 0.355 L of zinc sulfate heptahydrate at 2 mol / L to obtain an aqueous zinc ion electrolyte solution.

[0059] Comparative Example 4

[0060] Dissolve 10 μL of arginine at 20 mg / L in 1.24 L of deionized water. After thorough mixing, add 0.355 L of zinc sulfate heptahydrate at 2 mol / L to obtain a zinc ion electrolyte solution.

[0061] Result analysis:

[0062] like Figure 1 As shown, the left is the adsorption energy of 1-(2-pyridylazo)-2-naphthol on the zinc surface in a vertical state, which is -2.46 eV, and the middle is the adsorption energy of 1-(2-pyridylazo)-2-naphthol on the zinc surface in a horizontal state, which is -2.93. Both are much smaller than the adsorption energy of water molecules on the zinc surface (-0.68 eV), which indicates that the binding force between 1-(2-pyridylazo)-2-naphthol molecules and the zinc surface in the electrolyte is stronger than that between water molecules, confirming the strong interaction of pyridylazo compounds with metallic zinc.

[0063] Figure 2 This is the molecular dynamics simulation of the change of the solid-liquid interface of the zinc negative electrode. In the initial state, 1-(2-pyridyl azo)-2-naphthol and water are evenly distributed in the electrolyte. As the simulation progresses, 1-(2-pyridyl azo)-2-naphthol gradually approaches the zinc negative electrode and is finally adsorbed on the surface of the zinc negative electrode in a parallel state. Figure 1 The calculation results are consistent.

[0064] Since the adsorption of 1-(2-pyridyl azo)-2-naphthol reduces the contact between metal zinc and water, the corrosion resistance is enhanced in disguise. Figure 3 As shown in the figure, the comparison of the Tafel curves of Example 1 and Comparative Example 1 shows that the corrosion current after adsorption is 0.145 mA cm -2 The corrosion potential is -1.031 V, while the corrosion current of comparative example 2 is 2.451 mA cm -2 , the corrosion potential is -1.035V, indicating that the corrosion resistance of the aqueous zinc ion electrolyte prepared in Example 1 is stronger than that in Comparative Example 1.

[0065] Figure 4 The XRD graphs of zinc metal immersed in Example 1 and Comparative Example 1 show that the characteristic peak of the corrosion product Zn4SO4(OH)6·5H2O is detected in the XRD graph of Comparative Example 1, while no characteristic peak appears in Example 1. This indicates that 1-(2-pyridyl azo)-2-naphthol effectively inhibits HER.

[0066] Figure 5 The interaction energy between 1-(2-pyridylazo)-2-naphthol, water, zinc ion and 1-(2-pyridylazo)-2-naphthol of different configurations. The results show that 1-(2-pyridylazo)-2-naphthol has the strongest interaction with zinc ion (-1.82 eV) due to the rich lone electron pairs of pyridine nitrogen, azo and hydroxyl oxygen.

[0067] Figure 6 These are optical photographs of the electrolytes of Example 2 and Comparative Example 2. Due to the chelation between 1-(2-pyridyl azo)-2-naphthol and zinc ions, the solution changes from orange to pink-purple.

[0068] Figure 7 Figure 184 shows the UV spectra of Example 2 and Comparative Example 2. In Comparative Example 1, the characteristic peak representing 1-(2-pyridylazo)-2-naphthol is located at 470 nm. After chelation with zinc ions, the original characteristic peak at 470 nm disappears, and characteristic peaks representing the chelate appear at 500 nm and 530 nm, strongly confirming the strong interaction between 1-(2-pyridylazo)-2-naphthol and zinc ions.

[0069] Figure 8 Figure 187 shows the comparison of nucleation overpotentials of zinc-copper half-cells assembled using the electrolytes of Example 1 and Comparative Example 1. Due to the strong interaction between 1-(2-pyridylazo)-2-naphthol and zinc ions, the deposition behavior of zinc ions is optimized, and the nucleation overpotential of the zinc-copper half-cell increases from 34 mV to 47 mV.

[0070] Figure 9 Figure 190 shows the CA curves of zinc-zinc symmetric cells assembled using the electrolytes of Example 1 and Comparative Example 1. Due to the strong interaction between 1-(2-pyridylazo)-2-naphthol and zinc ions, the deposition behavior of zinc ions is optimized, and the two-dimensional diffusion process of zinc ions is reduced, making the current enter the plateau faster, that is, the three-dimensional diffusion region of zinc ions.

[0071] Figure 10 Figure 193 shows the ionic conductivities of the electrolytes of Example 1 and Comparative Example 1. After introducing 1-(2-pyridylazo)-2-naphthol, the ionic conductivity of the electrolyte decreases from 53.2 mS cm -1 to 50.3 mS cm -1 .

[0072] Figure 11 Figure 196 shows the in-situ optical tests of Example 1 and Comparative Example 1. At a current of 10 mA, Comparative Example 1 shows uncontrolled zinc dendrite growth, while Example 1 shows uniform deposition.

[0073] Figure 12 Figure 199 shows the COMSOL multiphysics simulation of zinc ion flow tests for Example 1 and Comparative Example 1. As the simulation time increases, the dark area at the zinc surface in Comparative Example 1 increases, and zinc deposition is concentrated at the tip, showing zinc dendrite growth. The simulation results of Example 1 show that zinc ions are uniformly deposited on the zinc surface. It is confirmed that 1-(2-pyridylazo)-2-naphthol adsorbed on the surface of metallic zinc has the effect of uniform zinc ion flow.

[0074] In addition, to further confirm the positive effect of 1-(2-pyridylazo)-2-naphthol on zinc ion batteries, button cells (CR2032) were assembled for charge-discharge tests:

[0075] As Figure 13 shown, at 2 mA cm -2 , 1 mAh cm-2 Under the same conditions, a zinc-zinc symmetric battery assembled with the aqueous zinc-ion electrolytes prepared in Example 1 and Comparative Example 1 was subjected to constant current charge-discharge tests. The test results showed that the battery assembled with Comparative Example 1 had a sudden voltage drop after 345 hours of cycling and short-circuited, while the battery assembled with Example 1 could stably cycle for 1500 hours, confirming the positive effect of 1-(2-pyridylazo)-2-naphthol on zinc-ion batteries.

[0076] The zinc-copper half-cells assembled with Comparative Example 1 and Example 1 were tested under the conditions of 5 mA cm -2 , 1 mAh cm -2 . The obtained Coulombic efficiency comparison chart is as Figure 14 shown. The battery corresponding to Comparative Example 1 had low efficiency after 850 cycles, manifested as abnormal charge and discharge, while the battery corresponding to Example 1 could stably cycle 3500 times, and the average Coulombic efficiency was 99.91%.

[0077] As Figure 15 shown, the constant current charge-discharge tests of all-battery with ammonium vanadate as the positive electrode and using Comparative Example 1 and Example 1 as the electrolyte were carried out under the condition of 1 A g -1 . The battery assembled with Example 1 had an initial discharge specific capacity of 235 mAh g -1 , and the capacity retention rate was 70% after 1300 cycles. The battery assembled with Comparative Example 1 had an initial discharge specific capacity of 230 mAh g -1 , and the capacity decayed to 100 mAh g -1 after 600 cycles. Experiments have proved that 1-(2-pyridylazo)-2-naphthol has a positive effect on zinc-ion batteries.

[0078] In addition, the test results of other examples and comparative examples except Example 1 and Comparative Example 1 are shown in Table 1 below. It should also be noted that except for the different preparation processes, the test methods of all examples and comparative examples are exactly the same. For details, please refer to the test methods of Example 1 and Comparative Example 1 above.

[0079] Table 1

[0080]

[0081] From the results of Examples 1 to 11, it can be seen that the electrolytes prepared by adjusting 1-(2-pyridylazo)-2-naphthol, 2-(5-nitro-2-pyridylazo)resorcinol, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, 2-(2-pyridylazo)-1-naphthol, 4-2-pyridylazo-N,N-dimethylaniline, 4-(2-pyridylazo)resorcinol, 4-(5-chloro-2-pyridylazo)-1,3-phenylenediamine, 4-(3,5-dibromo-2-pyridylazo)-1,3-phenylenediamine, 2-(2-pyridylazo)-5-dimethylaminophenol to 2-(5-nitro-2-pyridylazo)resorcinol, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, 2-(2-pyridylazo)-1-naphthol, 4-2-pyridylazo-N,N-dimethylaniline, 4-(2-pyridylazo)resorcinol, 4-(5-chloro-2-pyridylazo)-1,3-phenylenediamine, 4-(3,5-dibromo-2-pyridylazo)-1,3-phenylenediamine, 2-(2-pyridylazo)-5-dimethylaminophenol as additives can be used in zinc-zinc symmetric batteries, zinc-copper half-cells, and full cells and have good performance.

[0082] From Examples 1 and Comparative Example 1, it can be seen that the electrolytes without pyridylazo compounds have poor performance in various batteries such as zinc-zinc symmetric batteries, zinc-copper half-cells, and full cells. From Examples 1 and Comparative Example 2, it can be seen that the electrolytes obtained without adding zinc solution have much lower performance in various batteries such as zinc-zinc symmetric batteries, zinc-copper half-cells, and full cells than the electrolyte prepared in Example 1, indicating that there is a synergistic effect between the pyridylazo compounds and zinc ion solutions in this application.

[0083] From Examples 1 and Comparative Example 3, it can be seen that not all electrolytes prepared by mixing pyridylazo compounds with zinc ion solutions can exhibit good performance in various batteries such as zinc-zinc symmetric batteries, zinc-copper half-cells, and full cells, indicating the specificity of the pyridylazo compounds added in this application.

[0084] From Examples 1 and Comparative Example 4, it can be seen that when the additives added in this application are in trace amounts and are applied to various batteries such as zinc-zinc symmetric batteries, zinc-copper half-cells, and full cells, their performance is good. However, the electrolyte prepared from conventional additives in Comparative Example 4 has extremely poor performance when adding the same amount of trace amounts, which further demonstrates the advantages of the pyridylazo compounds added to the electrolyte prepared in this application.

[0085] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein may have other embodiments and can be implemented or realized in various ways.

Claims

1. A method for preparing an aqueous zinc ion electrolyte based on trace additives, characterized in that: The preparation method comprises: 1-500 mg / L of a pyridyl azo compound, 0.5-5 mol / L of a zinc salt and deionized water are mixed in a volume ratio of 1:35000-36000:123000-125000 to obtain an aqueous zinc ion electrolyte.

2. The method for preparing an aqueous zinc ion electrolyte based on trace additives according to claim 1, characterized in that: The pyridyl azo compound includes at least one group selected from the group consisting of pyridyl nitrogen, azo and phenolic hydroxyl.

3. The method for preparing an aqueous zinc ion electrolyte based on trace additives according to claim 1, characterized in that: The pyridyl azo compound includes at least one of 2-(5-nitro-2-pyridyl azo) resorcinol, 2-(5-bromo-2-pyridyl azo)-5-diethylaminophenol, 1-(2-pyridyl azo)-2-naphthol, 2-(2-pyridyl azo)-1-naphthol, 4-2-pyridyl azo-N,N-dimethylaniline, 4-(2-pyridyl azo) resorcinol, 4-(5-chloro-2-pyridyl azo) 1,3-phenylenediamine, 4-(3,5-dibromo-2-pyridyl azo) 1,3-phenylenediamine, and 2-(2-pyridyl azo)-5-dimethylaminophenol.

4. The method for preparing an aqueous zinc ion electrolyte based on trace additives according to claim 1, characterized in that: The zinc salt includes at least one of zinc sulfate heptahydrate, zinc trifluoromethanesulfonate, zinc chloride and zinc perchlorate hexahydrate.

5. The method for preparing an aqueous zinc ion electrolyte based on trace additives according to claim 1, characterized in that: The volume ratio of the pyridine azo compound, the zinc salt and the deionized water is 1:35650:124000.

6. An aqueous zinc ion electrolyte based on trace additives obtained according to the method for preparing an aqueous zinc ion electrolyte based on trace additives according to any one of claims 1 to 5.

7. The use of the aqueous zinc ion electrolyte based on trace additives in a zinc-zinc symmetrical battery according to claim 6, characterized in that: The applications include: Zinc metal is used as the positive and negative electrodes, the positive and negative electrodes are separated by a diaphragm, and an aqueous zinc ion electrolyte is used as the electrolyte to assemble a zinc-zinc symmetrical battery.

8. The use of the aqueous zinc ion electrolyte based on trace additives in a zinc-copper half-cell according to claim 6, characterized in that: The applications include: Zinc metal is used as the negative electrode, copper metal is used as the positive electrode, the positive and negative electrodes are separated by a diaphragm, and an aqueous zinc ion electrolyte is used as the electrolyte to assemble a zinc-copper half-cell.

9. The use of the aqueous zinc ion electrolyte based on trace additives in a full battery according to claim 6, characterized in that: The applications include: Zinc metal is used as the negative electrode, and the active material is used as the positive electrode. The positive and negative electrodes are separated by a separator, and the prepared electrolyte is dripped on the separator to assemble into a full battery; The active material includes at least one of ammonium vanadate, manganese dioxide, iodine, polyaniline, vanadium pentoxide, and sulfur.

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