A Wide-Temperature-Range Ester-Based Electrolyte and Its Application in Aqueous Zinc-Ion Batteries

Abstract

The present invention discloses a wide-temperature-range ester-based electrolyte, which relates to the technical field of electrolytes for aqueous zinc-ion batteries. The electrolyte comprises the following components: zinc salt, deionized water, organic solvent and organic salt additive; the organic solvent is diethylene glycol ethyl ether acetate; the organic salt additive is ammonium o-sulfobenzoate. The present invention also discloses the application of the above wide-temperature-range ester-based electrolyte in an aqueous zinc-ion battery and an aqueous zinc-ion battery. The electrolyte can inhibit the growth of zinc dendrites, improve the corrosion phenomenon related to active water on the zinc negative electrode, achieve effective protection of the zinc negative electrode, and greatly improve the cycle performance stability and service life of the aqueous zinc-ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc-ion battery electrolytes, and particularly relates to a wide-temperature-range ester-based electrolyte and its application in aqueous zinc-ion batteries. Background Art

[0002] The extensive dependence on fossil fuels and the growing energy demand are driving the development of the energy economy in a cleaner and more sustainable way. Aqueous zinc-ion batteries (AZIBs) have received extensive attention not only because of their low cost, much cheaper than lithium-ion battery (LIB) electrolytes, but also because they are inherently highly safe and environmentally friendly, with high theoretical volume / weight capacity (5855 mAh cm -3 , 820 mAh g -1 ), non-toxicity, abundant reserves (about 300 times that of lithium), and the prospect of easy large-scale production.

[0003] However, even though zinc metal provides a high hydrogen overpotential, enabling it to be immediately used as an electrode in aqueous electrolytes, its low redox potential (-0.76 V vs standard hydrogen electrode) makes the hydrogen evolution reaction (HER) on the surface inevitable. At the same time, aqueous zinc-ion batteries also face many challenges, such as severe side reactions, parasitic hydrogen evolution, and zinc dendrite growth, resulting in low Coulombic efficiency (CE) and shortened battery life. In particular, the growth of zinc dendrites not only causes rapid capacity decay but also reduces the reversibility of the zinc anode, thus accelerating battery failure. These all seriously hinder the large-scale application of aqueous zinc-ion batteries. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a wide-temperature-range ester-based electrolyte and its application in aqueous zinc-ion batteries. This electrolyte can inhibit the growth of zinc dendrites, improve the corrosion phenomenon related to active water on the zinc negative electrode, achieve effective protection of the zinc negative electrode, and greatly improve the cycle performance stability and service life of aqueous zinc-ion batteries.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: Provide a wide-temperature-range ester-based electrolyte, including the following components: zinc salt, deionized water, organic solvent, and organic salt additive; wherein, the organic solvent is diethylene glycol ethyl ether acetate; the organic salt additive is ammonium o-sulfobenzoate.

[0006] Further, the zinc salt is zinc perchlorate hexahydrate, and its concentration in the electrolyte is 0.5 - 3 mol / L.

[0007] Further, the volume fraction of the organic solvent in the electrolyte is 20% - 60%.

[0008] Furthermore, the concentration of the organic salt additive in the electrolyte is 0.01 - 0.03 mol / L.

[0009] Furthermore, the preparation method of the wide-temperature-range ester-based electrolyte is as follows: Mix an organic solvent and deionized water, then add a zinc salt and an organic salt additive, and then mix evenly by stirring and ultrasonic treatment.

[0010] The present invention also provides an application of the above-mentioned wide-temperature-range ester-based electrolyte in an aqueous zinc-ion battery.

[0011] The present invention also provides an aqueous zinc-ion battery, comprising a wide-temperature-range ester-based electrolyte, a positive electrode, a negative electrode, and a separator.

[0012] Furthermore, the separator is a sulfonic acid group-modified separator, and its preparation method is as follows: Mix polyethersulfone, polyvinylpyrrolidone, polyethylene glycol, polyetheretherketone, polyvinylidene fluoride, and dimethylacetamide according to a mass ratio of 2.5 - 3.5:0.5:0.2:0.2:0.1:16, stir and heat at 60 - 70 °C for 1 - 5 h to dissolve to obtain a spinning solution, then load it into a syringe, and perform electrospinning at room temperature. The working voltage during electrospinning is 19 kV, the working flow rate is 1.5 mL / h, and the distance between the needle and the collector is 18 cm to obtain the sulfonic acid group-modified separator.

[0013] The beneficial effect of adopting the further technical solution is that the sulfonic acid group-modified separator can effectively inhibit the shuttle effect of iodine in the aqueous zinc-iodine battery, which is beneficial to increasing the service life of the aqueous zinc-ion battery and improving the stability of its cycling performance.

[0014] The present invention has the following beneficial effects:

[0015] 1. The wide-temperature-range ester-based electrolyte of the present invention uses conventional drugs, has a simple preparation method, and the raw materials used are cheap and easily available, and can be obtained through a simple dissolution method. Furthermore, when applied to an aqueous zinc-ion battery, it shows good reversibility, high safety, and excellent electrochemical performance.

[0016] 2. The wide-temperature-range ester-based electrolyte of the present invention has excellent electrochemical performance: The symmetric zinc battery prepared by using it shows excellent cycling stability, and has a wide working temperature range. The stable cycling times at 25 °C, -25 °C, and 50 °C are 2300, 2700, and 700 hours respectively; the Zn / / Cu half-cell prepared by using it also shows an ultra-high Coulomb efficiency, and the stable cycling numbers at 25 °C, -25 °C, and 50 °C are 2300, 1000, and 1000 hours respectively; the Zn / / I 2 full cell shows higher stable cycling performance and capacity retention rate than the full cell using a pure zinc perchlorate electrolyte.

[0017] 3. Ammonium o-sulfobenzoate inhibits the growth of zinc dendrites and the corrosion phenomenon related to active water on the zinc anode by forming a solid electrolyte interface layer on the zinc surface, promotes a uniform zinc ion flux, helps to extend the service life of aqueous zinc-ion batteries, and improves the electrochemical performance of the batteries. Description of the Drawings

[0018] Figure 1 Long-term cycling comparison chart of symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1 at room temperature of 25 °C;

[0019] Figure 2 Long-term cycling comparison chart of symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1 at high temperature of 50 °C;

[0020] Figure 3 Long-term cycling comparison chart of symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1 at low temperature of -25 °C;

[0021] Figure 4 Coulombic efficiency comparison chart of Zn / Cu half-cells assembled with the electrolytes of Example 1 and Comparative Example 1;

[0022] Figure 5 SEM scanning image of the negative zinc electrode after 50 cycles at 25 °C of the symmetric zinc battery assembled with the electrolyte of Comparative Example 1;

[0023] Figure 6 SEM scanning image of the negative zinc electrode after 50 cycles at 50 °C of the symmetric zinc battery assembled with the electrolyte of Comparative Example 1;

[0024] Figure 7 SEM scanning image of the negative zinc electrode after 50 cycles at -25 °C of the symmetric zinc battery assembled with the electrolyte of Comparative Example 1;

[0025] Figure 8 SEM scanning image of the negative zinc electrode after 50 cycles at 25 °C of the symmetric zinc battery assembled with the electrolyte of Example 1;

[0026] Figure 9 SEM scanning image of the negative zinc electrode after 50 cycles at 50 °C of the symmetric zinc battery assembled with the electrolyte of Example 1;

[0027] Figure 10 SEM scanning image of the negative zinc electrode after 50 cycles at -25 °C of the symmetric zinc battery assembled with the electrolyte of Example 1;

[0028] Figure 11 XRD images of the negative zinc electrode after 50 cycles at 25 °C of the symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1;

[0029] Figure 12 The intensity comparison diagram of the Zn(002) crystal plane and the Zn(100) crystal plane of the negative zinc sheet after 50 cycles at 25 °C for the symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1;

[0030] Figure 13 The LSV curve diagram obtained with the electrolytes of Example 1 and Comparative Example 1;

[0031] Figure 14 The electron photo diagram of the sulfonic acid group modified separator;

[0032] Figure 15 The SEM scanning diagram of the sulfonic acid group modified separator;

[0033] Figure 16 The in-situ optical microscope diagram of the sulfonic acid group modified separator;

[0034] Figure 17 For the Zn / / I assembled with the electrolytes of Example 1 and Comparative Example 1 2 The long cycle diagram of the full battery at a current density of 2C. Detailed implementation manners

[0035] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0036] Example 1

[0037] A wide-temperature-range ester-based electrolyte, comprising the following components: zinc salt, deionized water, organic solvent and organic salt additive;

[0038] Among them, the organic solvent is diethylene glycol ethyl ether acetate, and its volume fraction in the electrolyte is 40%; the organic salt additive is ammonium o-sulfobenzoate, and its concentration in the electrolyte is 0.02 mol / L; the zinc salt is zinc perchlorate hexahydrate, and its concentration in the electrolyte is 1.5 mol / L.

[0039] Example 2

[0040] A wide-temperature-range ester-based electrolyte, comprising the following components: zinc salt, deionized water, organic solvent and organic salt additive;

[0041] Among them, the organic solvent is diethylene glycol ethyl ether acetate, and its volume fraction in the electrolyte is 20%; the organic salt additive is ammonium o-sulfobenzoate, and its concentration in the electrolyte is 0.01 mol / L; the zinc salt is zinc perchlorate hexahydrate, and its concentration in the electrolyte is 0.5 mol / L.

[0042] Example 3

[0043] A wide-temperature-range ester-based electrolyte, comprising the following components: zinc salt, deionized water, organic solvent, and organic salt additive;

[0044] Among them, the organic solvent is diethylene glycol ethyl ether acetate, and its volume fraction in the electrolyte is 60%; the organic salt additive is ammonium o-sulfobenzoate, and its concentration in the electrolyte is 0.03 mol / L; the zinc salt is zinc perchlorate hexahydrate, and its concentration in the electrolyte is 3 mol / L.

[0045] Example 4

[0046] An aqueous zinc-ion battery, comprising the wide-temperature-range ester-based electrolyte in Example 1, a positive electrode, a negative electrode, and a separator.

[0047] Comparative Example 1

[0048] An electrolyte, which is a 1.5 mol / L zinc perchlorate hexahydrate solution.

[0049] Test Example 1

[0050] Zn / Zn symmetric batteries and Zn / Cu half-cells were assembled using the electrolytes of Example 1 and Comparative Example 1 respectively, and the cycle numbers of the symmetric batteries and the Coulombic efficiency of the half-cells were tested under the conditions of a current density of 1 mA cm -2 and an areal capacity of 0.5 mAh cm -2 (1) The long-cycle comparison diagrams of the symmetric zinc batteries assembled using the electrolytes of Example 1 and Comparative Example 1 at room temperature of 25 °C are as shown in

[0051] (1) The long-cycle comparison diagrams of the symmetric zinc batteries assembled using the electrolytes of Example 1 and Comparative Example 1 at room temperature of 25 °C are as shown in Figure 1 As can be seen from the figure, after adding the organic solvent and the organic salt additive, the cycle life of the battery is significantly extended compared with that without addition.

[0052] (2) The long-cycle comparison diagrams of the symmetric zinc batteries assembled using the electrolytes of Example 1 and Comparative Example 1 at high temperature of 50 °C are as shown in Figure 2 As can be seen from the figure, after adding the organic solvent and the organic salt additive, the cycle life of the battery is significantly extended compared with that without addition.

[0053] (3) The long-cycle comparison diagrams of the symmetric zinc batteries assembled using the electrolytes of Example 1 and Comparative Example 1 at low temperature of -25 °C are as shown in Figure 3 As can be seen from the figure, after adding the organic solvent and the organic salt additive, the cycle life of the battery is significantly extended compared with that without addition.

[0054] (4) The Coulombic efficiency comparison diagrams of the Zn / Cu half-cells assembled using the electrolytes of Example 1 and Comparative Example 1 are as shown in Figure 4As shown. It can be observed from the experimental results that in the battery with the addition of organic solvent and organic salt additives, during the charge and discharge cycle, the insertion and extraction process of Zn 2+ ions becomes more reversible. After 2300 cycles, its Coulomb efficiency almost reaches 100%.

[0055] (5) The scanning (SEM) images of the negative zinc electrode after 50 cycles at 25 °C, 50 °C, and -25 °C for the symmetric zinc battery assembled with the electrolyte of Comparative Example 1 are respectively as Figures 5 - 7 shown. It can be clearly seen from the figure that the deposition of zinc ions on the zinc surface shows non-uniformity, and there are a large number of zinc dendrites. In addition, there are obviously a large number of by-products with a polygonal structure accumulated on the zinc foil surface.

[0056] The scanning (SEM) images of the negative zinc electrode after 50 cycles at 25 °C, 50 °C, and -25 °C for the symmetric zinc battery assembled with the electrolyte of Example 1 are respectively as Figures 8 - 10 shown. It can be clearly seen from the figure that zinc ions uniformly cover the zinc foil, making its surface show a smooth and uniform characteristic, which indicates that the added organic salt additive effectively inhibits the growth of dendrites and the formation of by-products.

[0057] (6) The XRD images of the negative zinc electrode after 50 cycles at 25 °C for the symmetric zinc battery assembled with the electrolytes of Example 1 and Comparative Example 1 are as Figure 11 shown. It can be clearly seen from the figure that for the battery assembled with the electrolyte of Comparative Example 1, the peak of by-product Zn 5 (OH) 8 Cl 2 ·xH 2 O can be clearly found. After adding ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate, the peak intensity of the by-product significantly decreases, which indicates that ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate can effectively inhibit the formation of by-products.

[0058] Furthermore, the intensity comparison diagram of the Zn(002) crystal plane and the Zn(100) crystal plane is as Figure 12 shown. It can be clearly seen from it that for the electrolyte of Comparative Example 1, the ratio of the Zn(002) crystal plane to the Zn(100) crystal plane is 2.04. After adding ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate, this ratio can be increased to 2.60, proving that ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate can effectively promote the selective deposition of zinc ions on the Zn(002) crystal plane, and then form a uniform zinc coating.

[0059] (7) The LSV curves obtained using the electrolytes of Example 1 and Comparative Example 1 are as Figure 13As shown, it can be clearly seen that the hydrogen evolution potential of the electrolyte added with ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate is significantly higher than that of the electrolyte in Comparative Example 1, proving that ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate can effectively inhibit the occurrence of hydrogen evolution side reactions in aqueous electrolytes.

[0060] Test Example 2

[0061] Polyethersulfone, polyvinylpyrrolidone, polyethylene glycol, polyetheretherketone, polyvinylidene fluoride and dimethylacetamide were mixed in a mass ratio of 3:0.5:0.2:0.2:0.1:16, stirred and heated at 65 °C for 4 h to dissolve to obtain a spinning solution, which was then filled into a syringe and electrospun at room temperature. The working voltage during electrospinning was 19 kV, the working flow rate was 1.5 mL / h, and the distance between the needle and the collector was 18 cm to prepare a sulfonic acid group modified separator.

[0062] (1) The electron micrograph of the sulfonic acid group modified separator is as Figure 14 shown. It can be clearly seen from the figure that the separator has flexibility, appears uniformly white as a whole, and can be bent and folded, ensuring its flexible adaptability and good mechanical properties in the battery.

[0063] (2) The SEM scan image of the sulfonic acid group modified separator is as Figure 15 shown. It can be clearly seen from it that the separator presents a fibrous filamentous structure.

[0064] (3) The in-situ optical microscope image of the sulfonic acid group modified separator is as Figure 16 shown. It can be clearly seen from it that the thickness of the separator is about 62 μm.

[0065] (4) The long cycle picture of the Zn / / I 2 all-battery assembled with the electrolyte, sulfonic acid group modified separator and iodine positive electrode at a current density of 2C is as Figure 17 shown. It can be clearly seen from it that compared with the electrolyte in Comparative Example 1, the all-battery assembled with the electrolyte containing ammonium o-sulfobenzoate and diethylene glycol ethyl ether acetate exhibits a higher reversible capacitance, and after 1200 charge-discharge cycles, its cycle stability shows more significant superiority.

[0066] In summary, when the wide-temperature-range ester-based electrolyte prepared by the present invention is applied in aqueous zinc-ion batteries, it effectively protects the zinc negative electrode and effectively inhibits the occurrence of side reactions such as dendrite formation and corrosion. This innovation not only significantly increases the service life of aqueous zinc-ion batteries, but also greatly improves the stability of their cycle performance. This is of great significance for promoting the industrial-scale production of aqueous zinc-ion batteries.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wide temperature range ester-based electrolyte, characterized in that: The method comprises the following components: zinc salt, deionized water, organic solvent and organic salt additive; The organic solvent is diethylene glycol ethyl ether acetate; The organic salt additive is ammonium o-sulfobenzoate.

2. The wide temperature range ester-based electrolyte according to claim 1, characterized in that: The zinc salt is zinc perchlorate hexahydrate, and the concentration of the zinc salt in the electrolyte is 0.5-3 mol / L.

3. The wide temperature range ester-based electrolyte according to claim 1, characterized in that: The volume fraction of the organic solvent in the electrolyte is 20%-60%.

4. The wide temperature range ester-based electrolyte according to claim 1, characterized in that: The concentration of the organic salt additive in the electrolyte is 0.01-0.03 mol / L.

5. The wide temperature range ester-based electrolyte according to claim 1, characterized in that: The preparation method comprises the following steps: mixing the organic solvent with deionized water, adding the zinc salt and the organic salt additive, and mixing the mixture uniformly by stirring and ultrasonic treatment.

6. Use of the wide temperature range ester-based electrolyte according to any one of claims 1 to 5 in an aqueous zinc ion battery.

7. An aqueous zinc ion battery, characterized in that: It comprises the wide temperature range ester-based electrolyte as claimed in claim 1, a positive electrode, a negative electrode and a separator.

8. The aqueous zinc ion battery according to claim 7, characterized in that: The diaphragm is a sulfonic acid modified diaphragm, and its preparation method is: polyethersulfone, polyvinyl pyrrolidone, polyethylene glycol, polyetheretherketone, polyvinylidene fluoride and dimethylacetamide are mixed in a mass ratio of 2.5-3.5:0.5:0.2:0.2:0.1:16, and stirred and heated at 60-70°C for 1-5h to dissolve to obtain a spinning solution, which is then loaded into a syringe and electrostatically spun at room temperature. The working voltage during spinning is 19kV, the working flow rate is 1.5mL / h, and the distance between the needle and the collector is 18cm, so as to obtain the sulfonic acid modified diaphragm.

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