Preparation method and application of wide-temperature-water-series zinc ion battery electrolyte

Abstract

The invention discloses a preparation method and application of a wide-temperature-water-series zinc ion battery electrolyte, and belongs to the technical field of water-series zinc ion batteries. According to the invention, proper zinc salt and tin dichloride additives are added into the ethylene glycol cosolvent, and the ionic conductivity is optimized and the low-temperature and high-temperature stability of the electrolyte is improved, so that the electrolyte can stably work in a wider temperature range, and the cycle performance of the aqueous zinc ion battery at an extreme temperature is improved. An innovative solution is provided for wide-temperature adaptability and high efficiency of the aqueous zinc ion battery, the service life of the battery is remarkably prolonged, and the overall performance of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc-ion batteries, and particularly to a preparation method and application of an electrolyte for a wide-temperature aqueous zinc-ion battery. Background Art

[0002] Entering the 21st century, with the rapid development of science and technology, the levels of industry and manufacturing have been successively improved, and the markets of electric vehicles and electronic devices have flourished. Among numerous energy storage devices and equipment, new electrochemical energy storage technologies have attracted extensive attention. At present, secondary lithium-ion batteries have achieved initial popularization and application in the fields of portable electronic devices, electric vehicles, and large-scale energy storage due to their high energy density, long lifespan, and easy portability. However, lithium resources in the earth's crust are limited and costly, making it difficult to meet large-scale energy storage for humans.

[0003] Currently, the commonly used electrolyte materials for aqueous zinc-ion batteries face a series of challenges, especially the impact on battery performance at extreme temperatures is particularly significant. Under low-temperature conditions, the aqueous electrolyte is prone to freezing when approaching zero degrees, resulting in a sharp decline in the fluidity and ion transport ability of the electrolyte. This freezing phenomenon will cause a significant reduction in the ionic conductivity of the battery, thereby affecting the charge-discharge efficiency, leading to a significant decrease in battery capacity, and even causing battery failure or damage in severe cases. In addition, in a low-temperature environment, the activity of water molecules in the electrolyte is relatively low, which also increases the internal resistance of the battery, reducing the overall performance and working stability. On the contrary, in a high-temperature environment, the electrolyte of the aqueous zinc-ion battery faces another challenge. High temperature will increase the activity of water molecules in the electrolyte, thereby exacerbating the growth of zinc dendrites. Zinc dendrites will not only reduce the cycle life of the battery but may also cause internal short circuits in the battery, resulting in battery failure. At the same time, too high a temperature may cause thermal decomposition of the electrolyte components, leading to the loss of the original chemical stability of the electrolyte, generating side reactions, and further reducing the performance and safety of the battery. For example, the zinc salt in the electrolyte may decompose into ineffective substances, even causing gas generation or electrolysis of water reactions, resulting in battery swelling or leakage. These problems have greatly restricted the reliability and stability of existing aqueous zinc-ion batteries in a wide temperature range, limiting their extensive application in some special application environments. Therefore, how to optimize the electrolyte composition and improve its stability at low and high temperatures has become an important research direction in aqueous zinc-ion batteries. In addition, the cycle stability and efficiency issues of aqueous zinc-ion batteries are also one of the important challenges faced by wide-temperature aqueous zinc-ion batteries. The intercalation process of zinc ions easily forms irreversible zinc dendrites on the surfaces of the positive and negative electrodes, thus affecting the service life of the battery. The requirements of the equipment and the harsh battery preparation conditions result in high production costs, severely restricting its further development and long-term use.

[0004] Based on the above problems, the development of aqueous zinc-ion batteries that can operate under wide temperature conditions has important scientific and practical significance. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing an electrolyte for a wide-temperature aqueous zinc-ion battery and its application to solve the problems raised in the background technology. By applying this electrolyte to zinc-ion batteries, the working temperature range of aqueous zinc-ion batteries is expanded, their electrochemical performance is improved, and the cycle life of the batteries is significantly extended, providing an effective solution for their efficient operation under wide-temperature conditions.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] An electrolyte for a wide-temperature aqueous zinc-ion battery, the electrolyte comprising a zinc salt, an alcohol organic solvent, and an inorganic additive.

[0008] Preferably, the zinc salt is zinc perchlorate hexahydrate; the alcohol organic solvent is ethylene glycol; the inorganic additive is a stannous chloride solution.

[0009] A method for preparing an electrolyte for a wide-temperature aqueous zinc-ion battery, comprising the following steps:

[0010] S1. Weigh zinc perchlorate hexahydrate into a beaker, add ethylene glycol, stir under ultrasonic waves until the solution is clear and transparent, and cool to room temperature;

[0011] S2. Add a stannous chloride solution to the mixed solution prepared in S1, stir at room temperature until the solution is clear and transparent to obtain a novel hydrated eutectic electrolyte.

[0012] Preferably, the amount of zinc perchlorate hexahydrate in S1 is 0.1 - 5 g.

[0013] Preferably, the amount of ethylene glycol in S1 is 1 - 10 mL.

[0014] Preferably, the ultrasonic stirring time in S1 is 15 - 25 min

[0015] Preferably, the volume fraction of the stannous chloride solution in S2 is 1 - 40%, and the concentration is 0.01 - 0.5 mo1 / L.

[0016] An application of an electrolyte for a wide-temperature aqueous zinc-ion battery, using the electrolyte for a wide-temperature aqueous zinc-ion battery to construct an aqueous zinc-ion battery.

[0017] Compared with the prior art, the present invention provides a method for preparing an electrolyte for a wide-temperature aqueous zinc-ion battery and its application, having the following beneficial effects:

[0018] (1) The present invention uses ethylene glycol as a co-solvent, which can significantly reduce the viscosity of the electrolyte at low temperatures, ensuring that the battery can still maintain high electrochemical performance under low-temperature conditions.

[0019] (2) During the preparation of the electrolyte, stannous chloride is added in the present invention, enhancing the stability of the electrolyte under high-temperature conditions, increasing the ion migration rate, preventing the decomposition or volatilization of the electrolyte at high temperatures, and ensuring the long-term stable operation of the battery.

[0020] (3) The present invention greatly broadens the operating temperature range of aqueous zinc-ion batteries. It can still inhibit dendrite growth at high and low temperatures, significantly extending the service life of aqueous zinc-ion batteries under high and low temperature conditions.

[0021] (4) The H2O molecules in the electrolyte prepared by the present invention can be restricted in the eutectic network through the dual actions of coordinating with Zn 2+ and forming hydrogen bonds with ethylene glycol. On the one hand, the activity of free water is weakened, expanding the electrochemical window of the mixed hydrated eutectic electrolyte; on the other hand, the hydrogen bond network between water molecules is disrupted, reducing the freezing point of the electrolyte. In addition, this hydrated eutectic electrolyte can in-situ form an interfacial layer on the surface of the zinc negative electrode, promoting the stability of the zinc anode and the rapid transmission of Zn 2+ to achieve uniform zinc deposition. Brief Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings involved in the embodiments are briefly introduced below. Obviously, the drawings in the following description are only schematic illustrations of some embodiments of the present invention. For those skilled in the art, other forms of drawings can be constructed based on these drawings without creative labor.

[0023] Figure 1 It is the cyclic data graph of the electrolyte symmetric battery at 30 °C under the conditions of 1 mA cm -2 / 1 mAh cm -2 in Example 1 of the present invention;

[0024] Figure 2 It is the cyclic data graph of the electrolyte symmetric battery at 30 °C under the conditions of 1 mA cm -2 / 1 mAh cm -2 in Comparative Example 1 of the present invention;

[0025] Figure 3 It is the cyclic data graph of the electrolyte symmetric battery at -30 °C under the conditions of 1 mA cm -2 / 1 mAh cm -2 in Example 1 of the present invention;

[0026] Figure 4 For Comparative Example 1 of the present invention, at -30°C, the electrolyte symmetric cell under 1 mA cm -2 / 1 mAh cm -2 Condition cycling data graph;

[0027] Figure 5 For Example 1 of the present invention, the SEM image of the electrolyte symmetric cell after 30 cycles under 1 mA cm -2 / 1 mAh cm -2 Condition;

[0028] Figure 6 For Comparative Example 1 of the present invention, the SEM image of the electrolyte symmetric cell after 30 cycles under 1 mA cm -2 / 1 mAh cm -2 Condition;

[0029] Figure 7 For Comparative Example 1 of the present invention, the constant volume charge-discharge data graph of the electrolyte symmetric cell under 1 mA cm -2 / 1 mAh cm -2 Condition;

[0030] Figure 8 For Example 1 of the present invention, the constant volume charge-discharge data graph of the electrolyte symmetric cell under 1 mA cm -2 / 1 mAh cm -2 Condition. Detailed implementation manners

[0031] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, these embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that without departing from the spirit and scope of the present invention, the details and forms of the technical solutions of the present invention can be modified or replaced, but such modifications and replacements all fall within the protection scope of the present invention.

[0032] It should be emphasized that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, devices, and materials are now described.

[0033] The present invention relates to a preparation method and application of an electrolyte for a wide-temperature aqueous zinc-ion battery, mainly solving the problems of unstable performance, poor ionic conductivity, and short cycle life of the electrolyte of the existing aqueous zinc-ion battery in low-temperature or high-temperature environments. Its core principle is to add appropriate zinc salts and tin dichloride additives to the ethylene glycol co-solvent, and by optimizing the ionic conductivity and improving the low-temperature and high-temperature stability of the electrolyte, the electrolyte can work stably in a wider temperature range, improving the cycle performance of the aqueous zinc-ion battery at extreme temperatures. The present invention improves the environment of the zinc negative electrode in the electrolyte and broadens the operating temperature range of the aqueous zinc-ion battery; a new hydrated eutectic electrolyte system composed of zinc perchlorate hexahydrate, ethylene glycol, and tin dichloride solution broadens the temperature range of the aqueous zinc-ion battery to -30°C to 30°C, greatly improving the reversibility of Zn and the life of the aqueous zinc-ion battery. The following will explain the wide-temperature aqueous zinc-ion battery electrolyte and its preparation method and application proposed by the present invention in combination with specific drawings and examples, and the specific content is as follows.

[0034] Example 1:

[0035] A preparation method of an electrolyte for a wide-temperature aqueous zinc-ion battery, comprising the following steps:

[0036] Step 1: Weigh 3.72 g of zinc perchlorate hexahydrate into a beaker, add 4.21 mL of ethylene glycol, and ultrasonicate at 30°C for 20 min until the mixed solution is clear and transparent, then cool to room temperature;

[0037] Step 2: Add a 0.2 mo1 / L tin dichloride solution with a volume fraction of 30% to the mixed solution in Step 1, stir at room temperature for 30 min, and wait until the solution is clear and transparent to obtain a new hydrated eutectic electrolyte, named ZnGSn-30.

[0038] Comparative Example 1:

[0039] A preparation method of an electrolyte for an aqueous zinc-ion battery, comprising the following content:

[0040] Weigh 3.72 g of zinc perchlorate hexahydrate into a beaker, add a small amount of deionized water to dissolve it, then transfer it to a 5 mL volumetric flask, add water to the scale, and dissolve it completely to obtain a 2 mo1 / L zinc perchlorate electrolyte, named 2M Zn.

[0041] Apply the electrolytes prepared in the above Example 1 and Comparative Example 1 to the zinc-ion battery, and assemble a button battery in the order of metallic zinc foil, commercial glass fiber separator, and metallic zinc foil. Design experiments to characterize their electrochemical performance, and the specific content is as follows:

[0042] Please refer to Figure 1-2 , Figure 1, 2 are the long-cycle diagrams of the symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1 at 30°C. It can be seen from the figure that even under the condition of high temperature of 30°C, the symmetric battery assembled with the novel hydrated eutectic electrolyte of Example 1 can still operate normally and can be stably cycled for 2000 h. However, the symmetric battery assembled with the electrolyte in Comparative Example 1 can only be cycled at high temperature for about 45 h, thus indicating that the novel hydrated eutectic electrolyte of the present invention has great tolerance to high temperature environments.

[0043] Please refer to Figure 3-4 , Figure 3 , 4 are the long-cycle diagrams of the symmetric zinc batteries assembled with the electrolytes of Example 1 and Comparative Example 1 at -30°C. It can be seen from the figure that even under the condition of low temperature of -30°C, the symmetric battery assembled with the novel hydrated eutectic electrolyte can still operate normally. Example 1 can be stably cycled for 2500 h, and Comparative Example 1 can be stably cycled for 25 h, which indicates that the novel hydrated eutectic electrolyte of the present invention has great tolerance to low temperature environments.

[0044] Please refer to Figure 5-6 , Figure 5 , 6 are the scanning diagrams of the zinc foils after 30 cycles at 30°C with a current density of 1 mA cm -2 and a capacity of 1 mAh cm -2 for the symmetric batteries assembled with the electrolytes of Example 1 and Comparative Example 1. For the zinc foil after cycling with zinc perchlorate electrolyte, the zinc is deposited unevenly on its surface, and there are large areas of zinc dendrites and by-products. However, for the battery assembled with the novel hydrated eutectic electrolyte, the zinc deposition on the surface of the zinc negative electrode is uniform, without zinc dendrites and by-products. Thus, it shows that the novel hydrated eutectic electrolyte of the present invention can effectively inhibit the generation of by-products and dendrites.

[0045] Figure 7 , 8 are the constant-volume charge-discharge data diagrams of the half-cells assembled with the electrolytes of Example 1 and Comparative Example 1 at a current density of 1 mA cm -2 and a capacity of 1 mAh cm -2 . For the battery assembled with the novel hydrated eutectic electrolyte, the overpotential during the charge-discharge process is stable between 38.5 mV, which is significantly lower than that of the half-cell assembled with zinc perchlorate electrolyte. This indicates that the zinc plating / stripping on the surface has high reversibility and it is easier to achieve zinc deposition, thus being beneficial to inhibiting dendrite formation. In contrast, for the half-cell assembled with 2M zinc perchlorate electrolyte, the overpotential rises to 52.6 mV, which indicates that side reactions and dendritic grains will continuously grow during the cycling process.

[0046] In summary, the novel wide-temperature hydrated eutectic electrolyte prepared by the present invention can significantly improve the stability and reversibility of aqueous zinc-ion batteries in the wide temperature range from -30°C to 30°C. This hydrated eutectic electrolyte plays a key role during the operation of the battery by in-situ generating an interfacial layer with special functions and a eutectic network structure. This eutectic network structure can effectively regulate the freezing point of the electrolyte, enabling it to maintain good ionic conductivity in a low-temperature environment, preventing the electrolyte from freezing, and thus ensuring the stable operation of the battery at low temperatures. In addition, the eutectic network structure in the electrolyte can form a protective interfacial layer on the surface of the battery's negative electrode, effectively inhibiting the growth of zinc dendrites and the corrosion reaction inside the battery. This not only reduces the short-circuit risk caused by dendrite penetration through the separator but also effectively prevents the occurrence of side reactions, thereby improving the cycle stability and long-term performance of the battery. In a high-temperature environment, the special eutectic structure can also reduce the thermal decomposition of the electrolyte, further ensuring the safety and reliability of the battery in harsh environments.

[0047] The proposed invention provides an innovative solution for the wide-temperature adaptability and high efficiency of aqueous zinc-ion batteries, significantly extending the service life of the batteries and improving their overall performance. This technology not only has important academic value but also lays a foundation for promoting the application of aqueous zinc-ion batteries in large-scale energy storage, automobiles, and other portable power systems.

[0048] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. A wide temperature aqueous zinc ion battery electrolyte, characterized in that: The electrolyte comprises zinc salt, alcohol organic solvent and inorganic additives.

2. A wide temperature aqueous zinc ion battery electrolyte according to claim 1, characterized in that: The zinc salt is zinc perchlorate hexahydrate; the alcohol organic solvent is ethylene glycol; and the inorganic additive is tin dichloride solution.

3. A method for preparing a wide temperature range aqueous zinc ion battery electrolyte as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Weigh zinc perchlorate hexahydrate into a beaker, add ethylene glycol, stir under ultrasound until the solution becomes clear and transparent, and cool to room temperature; S2. Add tin dichloride solution to the mixed solution prepared in S1, and stir at room temperature until the solution becomes clear and transparent to obtain a novel hydrated eutectic electrolyte.

4. The method for preparing a wide temperature aqueous zinc ion battery electrolyte according to claim 3, characterized in that: The amount of zinc perchlorate hexahydrate used in S1 is 0.1-5 g.

5. The method for preparing a wide temperature aqueous zinc ion battery electrolyte according to claim 3, characterized in that: The amount of ethylene glycol used in S1 is 1 to 10 mL.

6. The method for preparing a wide temperature range aqueous zinc ion battery electrolyte according to claim 3, characterized in that: The ultrasonic stirring time in S1 is 15 to 25 minutes.

7. The method for preparing a wide temperature range aqueous zinc ion battery electrolyte according to claim 3, characterized in that: The volume fraction of the tin dichloride solution in S2 is 1-40%, and the concentration is 0.01-0.5 mol / L.

8. An application of the wide temperature range aqueous zinc ion battery electrolyte as claimed in any one of claims 1 to 2, characterized in that: An aqueous zinc ion battery is constructed using the wide temperature aqueous zinc ion battery electrolyte.

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