CN115799664A

CN115799664A - Zinc ion battery electrolyte and preparation method and application thereof

Info

Publication number: CN115799664A
Application number: CN202211519302.0A
Authority: CN
Inventors: 古兴兴; 熊懿; 杜宜迅
Original assignee: Chongqing Technology and Business University
Current assignee: Chongqing Technology and Business University
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2023-03-14

Abstract

The invention relates to a zinc ion battery electrolyte and a preparation method and application thereof. The electrolyte can effectively overcome the problems of poor cycle performance, low coulombic efficiency, safety performance and the like of a ground battery caused by corrosion of a metal zinc cathode and uncontrollable dendritic crystal growth. Experiments prove that the zinc ion battery prepared by adopting the electrolyte of the invention has obviously improved cycle performance, rate performance and other electrochemical properties compared with the conventional zinc ion battery.

Description

Zinc ion battery electrolyte and preparation method and application thereof

Technical Field

The invention relates to the technical field of electrolyte, in particular to zinc ion battery electrolyte and a preparation method and application thereof.

Background

Lithium ion batteries play a crucial role in the energy field of modern society because of their advantages of higher energy density, long cycle life, good cycle performance, etc. However, on one hand, the lithium ion battery is difficult to meet the huge demand of the future market due to the scarcity of lithium resources; on the other hand, the dendrite problem of the lithium negative electrode can induce the short circuit of the battery, so that the combustion and explosion of the organic electrolyte are caused, and the safety performance is poor. Therefore, in recent years, researchers have been focusing on the development of a lithium negative electrode modification and a highly safe organic electrolyte, and also on the development of an aqueous secondary battery having a large global stock of raw materials and a higher safety.

Aqueous metal-ion batteries are an ideal choice for large-scale energy storage due to their high safety and low cost. Compared with other metals, metallic zinc has received much attention because of its high natural abundance, high weight/volume theoretical specific capacity, and low oxidation-reduction potential. In addition, because the zinc plating on the surface of the zinc cathode is not uniform, the corrosion of the metal zinc cathode and the uncontrollable dendritic crystal growth in the repeated charging and discharging process can seriously reduce the cycle performance, coulombic efficiency and even safety performance of the battery, and greatly hinder the commercialization progress of the zinc ion battery. Therefore, the inhibition of the formation of dendrites is of great significance for realizing the practical application of the aqueous solution zinc ion battery.

From the aspect of electrolyte modification, hexamethylene tetramine is added into zinc salt, and the zinc salt is high in electronegativity, easy to adsorb on the metal surface and complex with metal ions, so that an interface molecular layer is constructed in situ on the surface of a zinc cathode to stabilize the zinc cathode. The interface molecular film can regulate the uniform deposition of zinc ions and inhibit the growth of zinc dendrites on one hand; on the other hand, the zinc foil can be prevented from further contacting with water, and the coordination environment of zinc ions is changed, so that the generation of hydrogen evolution side reaction in the charging and discharging process is inhibited, and the corrosion of the zinc foil is prevented.

Disclosure of Invention

In view of the above, the invention provides a zinc ion battery electrolyte, and a preparation method and an application thereof, and the electrolyte can effectively overcome the problems of poor cycle performance, low coulombic efficiency, and even safety performance of a terrestrial battery caused by corrosion of a metal zinc cathode and uncontrolled dendritic crystal growth.

In order to achieve the technical purpose, the technical scheme adopted by the application is as follows:

in a first aspect, the present invention provides a zinc ion battery electrolyte composition comprising zinc sulfate and hexamethylenetetramine.

In a second aspect, the invention provides a zinc ion battery electrolyte comprising the above composition and a solvent.

Furthermore, in the electrolyte, the final concentration of zinc sulfate is 1-2 mol/L, and the final concentration of hexamethylene tetramine is 0.5-4 mg/mL.

Preferably, in the electrolyte, the final concentration of zinc sulfate is 2mol/L, and the final concentration of hexamethylenetetramine is 0.5-2 mg/mL.

More preferably, in the electrolyte, the final concentration of zinc sulfate is 2mol/L, and the final concentration of hexamethylene tetramine is 1mg/mL.

Further, the solvent is water.

In a third aspect, the present invention provides a method for preparing the above zinc ion battery electrolyte, including:

preparing a zinc sulfate solution with a certain concentration by using a solvent;

hexamethylene tetramine is added and mixed until the hexamethylene tetramine is completely dissolved.

In a fourth aspect, the invention provides an application of the zinc ion battery electrolyte in preparing a zinc ion battery.

In a fifth aspect, the invention provides a zinc ion battery comprising the above electrolyte.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, hexamethylene tetramine and zinc salt are compounded to form the modified electrolyte, so that the problems of poor cycle performance, low coulombic efficiency, safety performance and the like of the terrestrial battery caused by corrosion of a metal zinc cathode and uncontrollable dendritic crystal growth can be solved. Experiments prove that compared with the conventional zinc ion battery provided by the comparative example of the specific embodiment part, the zinc ion battery prepared by adopting the electrolyte disclosed by the invention has obviously improved cycle performance, rate performance and other electrochemical performances.

Drawings

In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:

fig. 1 is a graph of cycle performance test results of 4 Zn | Zn symmetric batteries in comparative example 2 and examples 1-3.

FIG. 2 is a graph showing the results of cycle performance tests of Zn symmetrical batteries without current density in comparative example 2 and example 2, in which FIG. 2-1 is 1mA cm ^-2 ，1mAh cm ^-2 Cycle performance ofTest results are shown in the figure, 2-2 is 2mA cm ^-2 ，2mAh cm ^-2 The results of the cycle performance test of (1) are shown in FIGS. 2 to 3 as 4mA cm ^-2 ，4mAh cm ^-2 The cycle performance test result chart of (1).

Fig. 3 is a graph showing corrosion current densities of 4 Zn | | | Zn symmetric batteries in comparative example 5 and examples 4-6.

Fig. 4 is an ac impedance diagram of a symmetrical battery of 4 Zn | in comparative example 2 and examples 1 to 3.

Fig. 5 is a hydrogen evolution reaction diagram of a 4 Zn | | | Zn symmetric cell in comparative example 2 and examples 1-3.

Fig. 6 is a graph of nucleation overpotentials for 2 Zn | Zn symmetric cells in comparative example 2 and example 2.

FIG. 7 is a cyclic voltammogram of 2 electrolytes in comparative example 6 and example 7, wherein FIG. 7-1 is a cyclic voltammogram of the electrolyte in example 7, and FIG. 7-2 is a cyclic voltammogram of the electrolyte in comparative example 6.

FIG. 8 is a first cycle charge and discharge graph of 2 electrolytes in comparative example 6 and example 7.

Fig. 9 is a plot of coulombic efficiency and electric capacity of 2 electrolytes of comparative example 6 and example 7.

FIG. 10 shows the total cell voltages of 0.2, 0.5, 1.0, and 2.0Ag for 2 electrolytes of comparative example 6 and example 7 ^-1 Magnification cycle plot under current.

Fig. 11 is an XRD characterization test chart of the materials in comparative example 2 and example 2.

Fig. 12 is an XPS characterization test chart of the materials in comparative example 2 and example 2.

Fig. 13 is a SEM characterization test chart of the materials in comparative example 2 and example 2.

Fig. 14 is a graph showing the results of cycle performance tests of Zn | | | Zn symmetric batteries of comparative example 7 and example 2.

Fig. 15 is a graph of cycle test results of zinc sulfate and zinc acetate electrolytes in experiment thirteen in a blue system.

Detailed Description

The invention provides a zinc ion battery electrolyte composition, which contains zinc sulfate and hexamethylenetetramine. Experiments prove that the electrolyte formed under the condition of compounding zinc sulfate and hexamethylene tetramine is used for a zinc ion battery, and various performances of the battery can be effectively improved.

The invention further provides a zinc ion battery electrolyte based on the electrolyte composition, which contains the composition and a solvent.

In the electrolyte, the final concentration of zinc sulfate is 1-2 mol/L, and the final concentration of hexamethylene tetramine is 0.5-4 mg/mL. The electrolyte formed in the range is used for assembling the zinc ion battery, and can effectively overcome the problems of poor cycle performance, low coulombic efficiency, safety performance and the like of the earth battery caused by corrosion of a metal zinc cathode and uncontrollable dendritic crystal growth.

Such as: in the electrolyte, the final concentration of zinc sulfate is 1mol/L, and the final concentration of hexamethylene tetramine is 0.5mg/mL. Or the final concentration of zinc sulfate is 1mol/L, and the final concentration of hexamethylene tetramine is 1mg/mL. Or the final concentration of the zinc sulfate is 1mol/L, and the final concentration of the hexamethylene tetramine is 2mg/mL. Or the final concentration of zinc sulfate is 1mol/L, and the final concentration of hexamethylene tetramine is 4mg/mL. Or the final concentration of the zinc sulfate is 2mol/L, and the final concentration of the hexamethylene tetramine is 0.5mg/mL. Or the final concentration of the zinc sulfate is 2mol/L, and the final concentration of the hexamethylene tetramine is 1mg/mL. Or the final concentration of the zinc sulfate is 2mol/L, and the final concentration of the hexamethylene tetramine is 2mg/mL. Or the final concentration of the zinc sulfate is 2mol/L, and the final concentration of the hexamethylene tetramine is 4mg/mL.

In the above combination, the final concentration of zinc sulfate is preferably 2mol/L and the final concentration of hexamethylenetetramine is preferably 1mg/mL.

The preparation method of the zinc ion battery electrolyte comprises the following steps: preparing a zinc sulfate solution with a certain concentration by using a solvent; hexamethylene tetramine is added and mixed until the hexamethylene tetramine is completely dissolved.

The electrolytes referred to in the following examples were prepared as follows:

(1) Weighing 14.387g of zinc sulfate hexahydrate, using a 25mL volumetric flask to fix the volume, and preparing blank ZnSO with the concentration of 2mol/L ₄ And (3) an electrolyte.

(2) 12.5mg of Hexamethylenetetramine (HMTA) was added in step (1)In the blank electrolyte prepared in the step (1), uniformly mixing and performing ultrasonic treatment until hexamethylenetetramine is completely dissolved to prepare ZnSO with the concentration of 2mol/L ₄ HMTA electrolyte at 0.5mg/mL.

(3) Adding 25mg of Hexamethylenetetramine (HMTA) into the blank electrolyte prepared in the step (1), uniformly mixing and ultrasonically treating until the hexamethylenetetramine is completely dissolved to prepare ZnSO with the concentration of 2mol/L ₄ HMTA electrolyte at 1mg/mL.

(4) Adding 50mg of Hexamethylenetetramine (HMTA) into the blank electrolyte prepared in the step (1), uniformly mixing and ultrasonically treating until the hexamethylenetetramine is completely dissolved to prepare ZnSO with the concentration of 2mol/L ₄ HMTA electrolyte at 2mg/mL.

In the description of the present invention, it is to be noted that those who do not specify specific conditions in the examples are performed according to conventional conditions or conditions recommended by the manufacturers. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The present invention will now be described in further detail with reference to the following figures and specific examples, which are intended to be illustrative, but not limiting, of the invention.

Example 1

Assembly of 2mol/L ZnSO ₄ Zn symmetrical battery with-0.5 mg/mL HMTA as electrolyte

Weighing 14.387g of zinc sulfate hexahydrate and 12.5mg of hexamethylenetetramine, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and the hexamethylenetetramine, and preparing the zinc sulfate hexahydrate with the concentration of 2mol/LznSO ₄ HMTA electrolyte at 0.5mg/mL.

In a button CR2032 battery mold, from bottom to top, a negative electrode shell, a zinc sheet (as a negative electrode) with a diameter of 16mm, a diaphragm (Glass micro filters) with a diameter of 16mm, a zinc sheet (as a positive electrode) with a diameter of 12mm, a gasket, a spring piece and a positive electrode shell are sequentially arranged, and when the negative electrode shell, the zinc sheet, the diaphragm and the positive electrode shell are arranged in sequence, 80uL (2 mol/L ZnSO) is arranged in the mold ₄ -0.5mg/mL HMTA) electrolyte is dripped on the diaphragm, after the assembly is finished, the button cell is finally sealed by a tablet press, and the Zn symmetrical cell is obtained by assembly.

Example 2

Assembly of 2mol/L ZnSO ₄ Zn symmetrical battery with-1 mg/mL HMTA as electrolyte

Weighing 14.387g of zinc sulfate hexahydrate and 25mg of hexamethylenetetramine, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and the hexamethylenetetramine to prepare the zinc sulfate hexahydrate with the concentration of 2mol/LZnSO ₄ -1mg/mL HMTA electrolyte.

In a button CR2032 battery die, from bottom to top, a negative electrode shell, a zinc sheet (as a negative electrode) with the diameter of 16mm, a diaphragm (Glass microfilters) with the diameter of 16mm, a zinc sheet (as a positive electrode) with the diameter of 12mm, a gasket, a spring sheet and a positive electrode shell are sequentially arranged, and 80uL (2 mol/L ZnSO) is arranged on the diaphragm ₄ -1mg/mL HMTA) electrolyte is dripped on the diaphragm, after the assembly is finished, the button cell is sealed by a tablet press, and the Zn symmetrical cell is obtained by assembly.

Example 3

Assembly of 2mol/L ZnSO ₄ Zn symmetrical battery with-2 mg/mL HMTA as electrolyte

Weighing 14.387g of zinc sulfate hexahydrate and 50mg of hexamethylenetetramine, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and the hexamethylenetetramine, and preparing the zinc sulfate hexahydrate with the concentration of 2mol/LznSO ₄ -1mg/mL HMTA electrolyte.

In a button CR2032 battery mold, from bottom to top, a negative electrode shell, a zinc sheet (as a negative electrode) with a diameter of 16mm, a diaphragm (Glass micro filters) with a diameter of 16mm, a zinc sheet (as a positive electrode) with a diameter of 12mm, a gasket, a spring piece and a positive electrode shell are sequentially arranged, and when the negative electrode shell, the zinc sheet, the diaphragm and the positive electrode shell are arranged in sequence, 80uL (2 mol/L ZnSO) is arranged in the mold ₄ -2mg/mL HMTA) electrolyte is dripped on the diaphragm, after the assembly is finished, the button cell is sealed by a tablet press, and the Zn symmetrical cell is obtained by assembly.

Example 4

Assembly of 2mol/L ZnSO ₄ Stainless steel | stainless steel symmetrical battery with-0.5 mg/mL HMTA as electrolyte

Weighing 14.387g of zinc sulfate hexahydrate and 12.5mg of hexamethylenetetramine, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and the hexamethylenetetramine to prepare concentrated solutionDegree of 2mol/LZnSO ₄ HMTA electrolyte at 0.5mg/mL.

In a button CR2032 battery die, from bottom to top, a negative electrode case, stainless steel (as a negative electrode) with a diameter of 16mm, a diaphragm (Glass micro filters) with a diameter of 16mm, stainless steel (as a positive electrode) with a diameter of 12mm, a gasket, a spring piece and a positive electrode case are sequentially arranged, and 80uL (2 mol/L ZnSO) is arranged on the diaphragm ₄ -0.5mg/mL HMTA) electrolyte is dripped onto the diaphragm, and after the assembly is completed, the button cell is finally sealed by a tablet press, and the Zn | symmetric cell is obtained by assembly.

Example 5

Assembly of 2mol/L ZnSO ₄ Stainless steel | stainless steel symmetrical battery with-1 mg/mL HMTA as electrolyte

In a button CR2032 battery die, from bottom to top, a negative electrode case, stainless steel (as a negative electrode) with a diameter of 16mm, a diaphragm (Glass micro filters) with a diameter of 16mm, stainless steel (as a positive electrode) with a diameter of 12mm, a gasket, a spring piece and a positive electrode case are sequentially arranged, and 80uL (2 mol/L ZnSO) is arranged on the diaphragm ₄ -0.5mg/mL HMTA) electrolyte is dripped on the diaphragm, after the assembly is finished, the button cell is finally sealed by a tablet press, and the Zn symmetrical cell is obtained by assembly.

Example 6

Assembly of 2mol/L ZnSO ₄ Stainless steel | stainless steel symmetrical battery with-2 mg/mL HMTA as electrolyte

Weighing 14.387g of zinc sulfate hexahydrate and 50mg of hexamethylenetetramine, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and the hexamethylenetetramine, and preparing the zinc sulfate hexahydrate with the concentration of 2mol/LznSO ₄ HMTA electrolyte at 2mg/mL.

In a button CR2032 battery die, a negative electrode shell, stainless steel (used as a negative electrode) with the diameter of 16mm and a diaphragm (Glass micro fiber li) with the diameter of 16mm are sequentially arranged from bottom to toplters), stainless steel (as positive electrode) with a diameter of 12mm, a spacer, a leaf spring, a positive electrode case, and when attached to the separator, 80uL (2 mol/L ZnSO) ₄ -0.5mg/mL HMTA) electrolyte is dripped on the diaphragm, after the assembly is finished, the button cell is finally sealed by a tablet press, and the Zn symmetrical cell is obtained by assembly.

Example 7

Assembly of 2mol/L ZnSO ₄ Zn-V with HMTA as electrolyte of-1 mg/mL ₂ O ₅ Full battery

Mixing vanadium pentoxide, conductive carbon black and pvdf according to a mass ratio of 7:2:1, stirring for 12h to prepare uniform electrode slurry, then coating the uniform electrode slurry on a stainless steel foil, wherein the coating thickness is 15 mu m, and condensing and drying for 24h to obtain the positive plate. Then ZnSO with the concentration of 2mol/L ₄ -1mg/mL HMTA solution as electrolyte.

In a button CR2032 battery die, a negative electrode shell, a zinc sheet (as a negative electrode) with the diameter of 16mm, a diaphragm (Glass micro filters) with the diameter of 16mm, a positive electrode sheet for preparing a positive electrode material, a gasket, a spring piece and a positive electrode shell are sequentially arranged from bottom to top, and 80uL electrolyte (2 mol/LZnSO) is added to the diaphragm ₄ -1mg/mL HMTA) is dripped on the diaphragm, after the assembly is finished, the button cell is sealed by a tablet press, and the Zn-V is obtained by the assembly ₂ O ₅ And (4) a full cell.

Comparative example 1

Assembling 1mol/L ZnSO ₄ Zn symmetrical battery using electrolyte

Weighing 7.1935g of zinc sulfate hexahydrate, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and prepare blank ZnSO with the concentration of 1mol/L ₄ And (3) an electrolyte.

In a button CR2032 cell mold, from bottom to top, a negative electrode shell, a zinc sheet (as a negative electrode) with a diameter of 16mm, a diaphragm (Glass micro filters) with a diameter of 16mm, a zinc sheet (as a positive electrode) with a diameter of 12mm, a gasket, a spring piece and a positive electrode shell are sequentially arranged, and when the negative electrode shell, the zinc sheet, the diaphragm and the positive electrode shell are arranged in sequence, 80uL (1 mol/L ZnSO) is arranged in the mold ₄ ) Dropwise adding electrolyte onto the diaphragm, and finally using a tablet press to make a button cell after the assembly is finishedAnd sealing, and assembling to obtain the Zn symmetrical battery.

Comparative example 2

Assembly of 2mol/L ZnSO ₄ Zn symmetrical battery using electrolyte

Weighing 14.387g of zinc sulfate hexahydrate, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and prepare blank ZnSO with the concentration of 2mol/L ₄ And (3) an electrolyte.

In a button CR2032 battery die, from bottom to top, a negative electrode shell, a zinc sheet (as a negative electrode) with the diameter of 16mm, a diaphragm (Glass microfilters) with the diameter of 16mm, a zinc sheet (as a positive electrode) with the diameter of 12mm, a gasket, a spring sheet and a positive electrode shell are sequentially arranged, and 80uL (2 mol/L ZnSO) is arranged on the diaphragm ₄ ) And dropwise adding the electrolyte onto the diaphragm, sealing the button cell by using a tablet press after the assembly is finished, and assembling to obtain the Zn symmetrical cell.

Comparative example 3

Assembly of 3mol/L ZnSO ₄ Zn symmetrical battery using Zn as electrolyte

Weighing 21.5805g of zinc sulfate hexahydrate, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and prepare blank ZnSO with the concentration of 3mol/L ₄ And (3) an electrolyte.

In a button CR2032 battery mold, from bottom to top, a negative electrode shell, a zinc sheet (as a negative electrode) with a diameter of 16mm, a diaphragm (Glass micro filters) with a diameter of 16mm, a zinc sheet (as a positive electrode) with a diameter of 12mm, a gasket, a spring piece and a positive electrode shell are sequentially arranged, and when the negative electrode shell, the zinc sheet, the diaphragm and the positive electrode shell are assembled, 80uL (3 mol/L ZnSO) is added ₄ ) And dropwise adding the electrolyte on the diaphragm, after the assembly is finished, finally sealing the button cell by using a tablet press, and assembling to obtain the Zn symmetrical cell.

Comparative example 4

Assembling 4mol/L ZnSO ₄ Zn symmetrical battery using Zn as electrolyte

Weighing 28.774g of zinc sulfate hexahydrate, fixing the volume with a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc sulfate hexahydrate and prepare the zinc sulfate hexahydrate with the concentration of 4molBlank ZnSO of/L ₄ And (3) an electrolyte.

In a button CR2032 battery die, a negative electrode shell, a zinc sheet (as a negative electrode) with the diameter of 16mm, a diaphragm (Glass microfilters) with the diameter of 16mm, a zinc sheet (as a positive electrode) with the diameter of 12mm, a gasket, a spring sheet and a positive electrode shell are sequentially arranged from bottom to top, and 80uL (4 mol/L ZnSO) is arranged on the diaphragm ₄ ) And dropwise adding the electrolyte onto the diaphragm, sealing the button cell by using a tablet press after the assembly is finished, and assembling to obtain the Zn symmetrical cell.

Comparative example 5

Assembly of 2mol/L ZnSO ₄ Stainless steel symmetrical battery using electrolyte

In a button CR2032 battery mold, a negative electrode shell, a stainless steel sheet (as a negative electrode) with the diameter of 16mm, a diaphragm (Glass micro filters) with the diameter of 16mm, a stainless steel sheet (as a positive electrode) with the diameter of 12mm, a gasket, a spring piece and a positive electrode shell are sequentially arranged from bottom to top, and 80uL (2 mol/L ZnSO) is arranged on the diaphragm ₄ ) And dropwise adding the electrolyte on the diaphragm, after the assembly is finished, sealing the button cell by using a tablet press, and assembling to obtain the stainless steel symmetrical cell for testing the ionic conductivity.

Comparative example 6

Assembly of 2mol/L ZnSO ₄ Zn-V as electrolyte ₂ O ₅ Full battery

Mixing vanadium pentoxide, conductive carbon black and pvdf according to a mass ratio of 7:2:1, stirring for 12 hours to prepare uniform electrode slurry, then coating the electrode slurry on a stainless steel foil, and condensing and drying for 24 hours to obtain the positive plate. Then at a concentration of 2mol/LZnSO ₄ The solution of (2) is used as an electrolyte.

In a button CR2032 battery die, a negative electrode shell, a zinc sheet (as a negative electrode) with the diameter of 16mm, a diaphragm (Glass micro filters) with the diameter of 16mm and a positive electrode material are sequentially prepared from bottom to topWhen the positive plate, the gasket, the spring piece and the positive shell are arranged on the diaphragm, 80uL of electrolyte (2 mol/LZnSO) is added ₄ ) Dripping the mixture on a diaphragm, sealing the button cell by a tablet press after the assembly is finished, and assembling to obtain Zn-V ₂ O ₅ And (4) full cell.

Comparative example 7

Assembling 2mol/L Zn (CH) ₃ COOH) ₂ Zn symmetrical battery with-1 mg/mL HMTA as electrolyte

Weighing 10.978g of zinc acetate dihydrate and 25mg of hexamethylenetetramine, fixing the volume by using a 25mL volumetric flask, putting the volumetric flask into a numerical control ultrasonic cleaner for ultrasonic treatment to completely dissolve the zinc acetate dihydrate and the hexamethylenetetramine, and preparing the zinc acetate dihydrate with the concentration of 2mol/LZn (CH) ₃ COOH) ₂ -1mg/mLHMTA electrolyte.

Zn | Zn symmetric cells were assembled in the manner of example 2.

Performance testing of the above cases:

experiment one: comparison of cycle Performance of Zn symmetrical batteries of comparative examples 1 to 4

Setting the charging and discharging current of 1.0mA cm in the blue electricity circulating system for the 4 Zn symmetrical batteries obtained in the way ^-2 The fixed charging and discharging capacity is 1mAh cm ^-2 The cycle performance test under the condition proves that when the concentration is 2mol/L ZnSO ₄ The Zn-Zn symmetrical battery of the electrolyte shows the best cycle stability when ZnSO ₄ Has no cycle performance of 2mol/L ZnSO no matter whether the concentration of the ZnS is increased or reduced ₄ The cycle performance as an electrolytic solution (comparative example 2) was excellent.

Experiment two: comparative example 2 comparison of the cycling Performance of the Zn symmetrical batteries of examples 1-3

Setting the charging and discharging current of 1.0mA cm in the blue electricity circulating system for the 4 Zn symmetrical batteries obtained in the way ^-2 The fixed charging and discharging capacity is 1mAh cm ^-2 The results of the cycle performance test under the conditions are shown in FIG. 1, and it can be seen from FIG. 1 that the concentration of ZnSO was 2mol/L ₄ Zn symmetrical battery with-1 mg/mL HMTA electrolyte shows the best circulation stability, and the next step is ZnSO with concentration of 2mol/L ₄ Zn symmetrical electrode of-2 mg/mL HMTA electrolyteThe cell was then ZnSO with a concentration of 2mol/L ₄ The Zn | Zn symmetric battery with-0.5 mg/mL HMTA electrolyte shows better cycling stability, and the cycling performance of the Zn | Zn symmetric battery is increased and then reduced along with the increase of the concentration of the HMTA, and the reason probably is that enough active sites cannot be formed to induce Zn when the concentration of the HMTA in the electrolyte is insufficient ²⁺ The deposition of (2) results in failure to effectively inhibit corrosion of the Zn negative electrode and growth of Zn dendrites, and when the HMTA in the electrolyte is excessive, the conductivity in the solution is reduced due to non-conductivity of the electrolyte, so that the cycle performance is reduced.

Experiment three: comparison of the cycle performance of the Zn symmetrical battery of comparative example 2 and example 2 under different multiplying power

Setting the charging and discharging current to be 1.0mA cm in the blue test system for placing the obtained 2 Zn symmetrical batteries ^-2 The fixed charging and discharging capacity is 1mAh cm ^-2 The cycle performance test is carried out under the condition that the charging and discharging current is 2.0mA cm ^-2 The fixed charging and discharging capacity is 2mAh cm ^-2 The cycle performance test and the charging and discharging current are 4.0mA cm ^-2 The fixed charging and discharging capacity is 4mAh cm ^-2 And (4) carrying out cycle performance test under the condition.

The test results are shown in FIG. 2, and it can be seen that the current density is 1mA cm regardless of whether the current density is ^-2 ，2mA cm ^-2， Or 4mA cm ^-2 It is obvious that ZnSO with the concentration of 2mol/L is used ₄ The circulation performance of the Zn symmetrical battery with-1 mg/mL HMTA electrolyte is far higher than that of the Zn symmetrical battery with 2mol/L ZnSO ₄ The blank control electrolyte of (1).

Experiment four: test of ionic conductivity of symmetric stainless steel batteries of comparative example 5 and examples 4 to 6

For 4 stainless steel | stainless steel symmetric batteries in the obtained experimental group, the low frequency is 0.01Hz, the high frequency is 100000Hz, and the initial voltage is 0.01V in the electrochemical workstation chi660e, and the ionic conductivity is tested.

As shown in fig. 3, it is understood from fig. 3 that the ion conductivity decreases as the concentration of hexamethylenetetramine increases. This is because hexamethylenetetramine is not conductive and the ionic conductivity of the electrolyte is slightly lowered, and therefore, it is preferable to control the concentration of hexamethylenetetramine to about 1mg/mL.

Experiment five: AC impedance performance test of Zn symmetrical batteries of comparative example 2 and examples 1 to 3

For the 4 Zn | Zn symmetric batteries in the experimental group obtained above, the alternating-current impedance was tested by setting the low frequency to 0.01Hz, the high frequency to 100000Hz, and the initial voltage to 0.01V in the electrochemical workstation chi660 e.

The test result is shown in fig. 4, as the concentration of hexamethylenetetramine increases, the alternating current impedance also continuously increases, and the result is exactly corresponding to the ionic conductivity result shown in fig. 3, the reason is that the impedance also increases due to the non-conductivity of hexamethylenetetramine, and the increase of the impedance causes a certain increase of nucleation overpotential, which is beneficial to grain refinement and inhibits the growth of crystal branches, so that the cycle time of the battery is longer.

Experiment six: hydrogen evolution curve test of Zn symmetrical batteries of comparative example 2 and examples 1-3

For the 4 kinds of Zn symmetrical batteries obtained in the above, the initial voltage is-0.5V and the final voltage is 0.5V in the electrochemical workstation chi660e, and the hydrogen evolution curve diagram is tested.

As shown in fig. 5, the hydrogen evolution potential shifted in the negative direction with the increase of the HMTA concentration in the electrolyte, indicating that the addition of HMTA can suppress the hydrogen evolution reaction, and that the suppression of the hydrogen evolution reaction is most significant when the HMTA concentration is 1mg/mL.

Experiment seven: nucleation overpotential test of Zn | Zn symmetric batteries of comparative example 2 and example 2

The electrolyte of the 4 kinds of Zn | Zn symmetric batteries obtained above was assembled according to the battery assembly method in embodiments 1-4 to obtain a Zn | Cu symmetric battery. And was tested for nucleation overpotentials using a blue-electron system.

As shown in FIG. 6, with the addition of HMTA, the nuclear overpotential is increased, and the higher nucleation overpotential is favorable for the grain size reduction in the initial stage of zinc deposition, so that Zn is obtained ²⁺ The deposition is more uniform when 2mol/LZnSO is used ₄ The nucleation overpotential of the electrolyte solution of (1) is 32mV, and when used at a concentration of 2mol/LZnSO ₄ The nucleation overpotential of the electrolyte is 51mV at-1 mg/mLHMTA electrolyte. This can just show that the addition of HMTA, although reducing the ionic conductivity to some extent, also promotes the nucleation overpotential, thereby facilitating the grain refinement at the initiation of nucleation, making the zinc deposition uniform and inhibiting the growth of dendrites.

Experiment eight: CV test was performed for the full cells of comparative example 6 and example 7

The full cell was tested at the chi660e electrochemical workstation and the results are shown in FIG. 7, which is a CV cycle voltammogram of the full cell, from which it can be seen that 2mol/L ZnSO was used ₄ The full cell of-1 mg/mLHMTA electrolyte has better superposition performance in 3 cycles of circulation in the figure, which indicates that the full cell has better electrochemical stability. Experiment nine: constant current charge and discharge curves of the full cells of comparative example 6 and example 7

As shown in FIG. 8, it can be observed that 2mol/LZnSO was used ₄ Initial specific discharge capacity of 280mAh g for full cell of-1 mg/mL HMTA electrolyte ^-1 165mAh g higher than blank electrolyte ^-1 This shows that 2mol/L ZnSO is used ₄ Reversibility of full cell of-1 mg/mL HMTA electrolyte higher than 2mol/LZnSO ₄ The electrolyte of (4).

Experiment ten: long cycle performance plots for the full cells of comparative example 6 and example 7

FIG. 9 shows a cross-section at 2Ag ^-1 Long cycle performance of the complete cells tested. In the presence of 2mol/LznSO ₄ Full battery coulombic efficiency of-1 mg/mLHMTA electrolyte is close to 100%, and after 500 cycles of its cycling, the battery capacity remains at 200mAh g ^-1 . While the coulombic efficiency in the case of using the blank electrolyte is only approximately 95%, the capacity of the battery after 500 cycles is only 60mAh g ^-1 . Shows that the electrolyte has higher coulombic efficiency and battery capacity retention rate compared with a blank electrolyte after using hexamethylenetetramine as an electrolyte additive

Experiment eleven: full cell rate performance plots for comparative example 6 and example 7

As shown in FIG. 10, it can be observed that 2mol/LZnSO was used ₄ Initial specific discharge capacity of 280mAh g for full cell of-1 mg/mL HMTA electrolyte ^-1 165mAh g higher than blank electrolyte ^-1 This means that 2mol/LznSO are used ₄ Reversibility of full cell of-1 mg/mL HMTA electrolyte higher than 2mol/LznSO ₄ The full cell of the electrolyte of (1).

Experiment twelve: zn negative pole characterization before and after circulation of Zn | Zn symmetric batteries of comparative example 2 and example 2

The batteries in comparative example 1 and example 5 were disassembled before and after 3 cycles of charge and discharge reaction, and the zinc negative electrode was removed, washed with a large amount of absolute ethanol, and after washing, placed in a vacuum drying oven, and dried, and the zinc negative electrode was used as a characterization test of a material.

FIG. 11 shows a zinc negative electrode using 2mol/LZnSO ₄ After 3 cycles of-1 mg/mL HMT electrolyte, 2mol/L ZnSO was used ₄ XRD tests are carried out on the zinc cathode after 3 cycles and pure Zn foil, and the XRD characteristic diagram shows that after 3 cycles, zn appears on the surface of the zinc cathode circulating in the blank electrolyte ₄ SO ₄ (OH) ₆ ·H ₂ Characteristic XRD peak of O. However, on the zinc cathode using hexamethylenetetramine electrolyte additive, zn was hardly observed ₄ SO ₄ (OH) ₆ ·H ₂ Characteristic XRD peak of O, which shows that the addition of HMTA inhibits Zn ₄ SO ₄ (OH) ₆ ·H ₂ The formation of O by-product, namely, the corrosion of Zn negative electrode is suppressed. To further examine the effect of hexamethylenetetramine on zinc cathodes, the concentration of hexamethylenetetramine on zinc cathodes was 2mol/LZnSO ₄ After HMTA of-1 mg/mL is used as an electrolyte and circulated for 3 circles, and then washed by ethanol, an xps test is carried out, as shown in FIG. 12, it can be observed that the Zn cathode surface can be tested to contain C and N elements, and the two elements can only be hexamethylenetetramine additives from us, which indicates that an interface molecular layer can be built in situ on the zinc cathode surface by adding the HMTA. Finally respectively aligning 2mol/L ZnSO ₄ Is electrolyte and 2mol/LZnSO ₄ SEM test of zinc cathode after HMTA of 1mg/mL is taken as electrolyte circulation loop, and the test result is shown in figure 13 when we do not addIn the case of hexamethylenetetramine, a large amount of zinc dendrites are generated on the zinc cathode, and 2mol/LZnSO ₄ The zinc cathode with HMTA of-1 mg/mL as electrolyte is very smooth and has no zinc dendrite formation.

Experiment thirteen: comparative example 7 comparison of cycling performance of Zn symmetrical cells of example 2

ZnSO at 2mol/L ₄ Electrolyte and 2mol/L of Zn (CH) ₃ COOH) ₂ When both electrolytes are added with the hexamethylenetetramine electrolyte additive of 1mg/mL, the circulating performance can be circulated for more than 2000 hours by using the hexamethylenetetramine electrolyte additive of 2mol/L zinc sulfate +1mg/mL, while the circulating performance can be circulated for less than 500 hours by using the hexamethylenetetramine electrolyte additive of 2mol/L zinc acetate +1mg/mL, when the HMT concentrations are the same, and the results are shown in FIG. 14.

In addition, the invention is suitable for 2mol/L ZnSO ₄ Electrolyte and 2mol/L Zn (CH) ₃ COOH) ₂ The performances of the electrolytes are compared, and the performance measuring method comprises the following steps: 2mol/L zinc sulfate and 2mol/L zinc acetate are both prepared for cycle test in a blue electricity system, and the result is shown in figure 15, the Zn cathode is 2mol/L ZnSO ₄ The performance of the electrolyte is better than that of Zn (CH) of 2mol/L ₃ COOH) ₂ However, the cycle performance in the two electrolytes is not more than 70 hours, which is far lower than the cycle hours of the Zn negative electrode after the two electrolytes are compounded with the hexamethylenetetramine electrolyte additive, and the research result is helpful for the subsequent zinc ion battery electrolyte to develop more intensive research.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A zinc ion battery electrolyte composition, characterized in that: contains zinc sulfate and hexamethylenetetramine.

2. The zinc ion battery electrolyte of claim 1, wherein: comprising the composition of claim 1 and a solvent.

3. The zinc ion battery electrolyte of claim 2, wherein: in the electrolyte, the final concentration of zinc sulfate is 1-2 mol/L, and the final concentration of hexamethylene tetramine is 0.5-4 mg/mL.

4. The zinc ion battery electrolyte of claim 2 or 3, wherein: in the electrolyte, the final concentration of zinc sulfate is 2mol/L, and the final concentration of hexamethylene tetramine is 0.5-2 mg/mL.

5. The zinc ion battery electrolyte of claim 4, wherein: in the electrolyte, the final concentration of zinc sulfate is 2mol/L, and the final concentration of hexamethylenetetramine is 1mg/mL.

6. The electrolyte for a zinc ion battery of claim 2, wherein: the solvent is water.

7. The method for preparing the electrolyte for zinc ion batteries according to any one of claims 2 to 6, wherein: the method comprises the following steps:

hexamethylene tetramine is added and mixed until complete dissolution.

8. Use of the zinc ion battery electrolyte according to any one of claims 2 to 6 or the zinc ion battery electrolyte obtained by the preparation method according to claim 7 for the preparation of a zinc ion battery.

9. A zinc-ion battery, characterized by: the battery comprises the zinc ion battery electrolyte as defined in any one of claims 2 to 6 or the zinc ion battery electrolyte obtained by the preparation method as defined in claim 7.