Deep eutectic electrolyte, preparation method thereof, zinc ion battery and electric device

Abstract

The invention belongs to the technical field of batteries, and particularly discloses a deep eutectic electrolyte and a preparation method thereof, a zinc ion battery and an electric device, the deep eutectic electrolyte comprises a zinc salt, an alcohol solvent and deionized water; wherein the molar ratio of the zinc salt to the alcohol solvent to the deionized water is 1: (2-3): (8-16). Therefore, the deep eutectic electrolyte has a relatively low freezing point, and the zinc ion battery adopting the deep eutectic electrolyte has relatively good cycle performance under an extremely low temperature condition.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and specifically relates to a deep eutectic electrolyte and its preparation method, a zinc-ion battery, and an electrical device. Background Art

[0002] Due to the advantages of zinc anode such as low electrochemical potential, rechargeable zinc aqueous batteries have broad application prospects in the new generation of energy storage technologies, with high theoretical capacity and low cost. However, water, as the main component of aqueous electrolytes, usually freezes at 0°C under standard atmospheric pressure. At low temperatures, the frozen electrolyte will cause hindered ion transport, deterioration of the electrode / electrolyte interface, capacity reduction, and battery failure. Therefore, determining how to keep the aqueous electrolyte in a liquid state is the basis for constructing low-temperature aqueous zinc batteries. So far, various methods have been adopted to design low-temperature electrolytes, such as using high-concentration electrolytes, organic additives, and antifreeze hydrogel electrolytes. Nevertheless, these methods still have some problems in practical applications, such as the high cost of high-concentration electrolytes, the addition of harmful and toxic organic substances, and the additional preparation of hydrogel electrolytes. Therefore, low-temperature-resistant zinc-ion battery electrolytes still need further research. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems in the related art to some extent. For this purpose, this application proposes a deep eutectic electrolyte with low temperature resistance, environmental friendliness, or simplicity and high efficiency, its preparation method, a zinc-ion battery, and an electrical device.

[0004] In the first aspect of this application, a deep eutectic electrolyte is proposed, including: zinc salt, alcohol solvent, deionized water; wherein, the molar ratio range of the zinc salt, the alcohol solvent, and the deionized water is 1:2-3:8-16. Thus, this deep eutectic electrolyte has a relatively low freezing point, and when it is applied to a zinc-ion battery, it can improve the low-temperature cycling performance of the battery.

[0005] In some embodiments, when the alcohol solvent is one or two kinds, the molar ratio range of the zinc salt, the alcohol solvent, and the deionized water is 1:2:8-16. Thus, it is beneficial for the reaction to be more complete and reduce raw material waste.

[0006] In some embodiments, when the alcohol solvent is three kinds, the molar ratio range of the zinc salt, the alcohol solvent, and the deionized water is 1:3:8-16. Thus, it is beneficial for the reaction to be more complete and reduce raw material waste.

[0007] In some embodiments, the zinc salt includes a sulfonic acid-based zinc salt.

[0008] In some embodiments, the zinc salt includes at least one of zinc methanesulfonate, zinc 1,2-ethanedisulfonate, and zinc propane sulfonate. Thus, the material source is wide and the cost is low, which can provide the ionic conductivity required for the deep eutectic electrolyte.

[0009] In some embodiments, the alcohol solvent includes at least one of ethylene glycol, glycerol, and xylitol. Thus, the material source is wide, and using an alcohol solvent to prepare the deep eutectic electrolyte can inhibit the freezing of water, enabling the zinc-ion battery to maintain good ionic conductivity and stability at low temperatures.

[0010] A second aspect of the present application provides a method for preparing a deep eutectic electrolyte, including: mixing a zinc salt, an alcohol solvent, and deionized water to obtain a raw material mixture; heating the raw material mixture to clarity and keeping it stably clear for 6 h to 12 h to obtain the deep eutectic electrolyte. The deep eutectic electrolyte prepared in this way is green and environmentally friendly, has a low freezing point, and can enable the battery to stably cycle at low temperatures when applied to a zinc-ion battery.

[0011] In some embodiments, an oil bath is used to heat and dissolve the raw material mixture. Thus, it is convenient to control the temperature, the heating process is uniform, the operation is convenient, and it is beneficial to form a eutectic system.

[0012] In some embodiments, the heating temperature is 80°C to 100°C, and the heating time is 2 h to 6 h. Thus, it is beneficial to make the reaction more complete and then form a eutectic system.

[0013] A third aspect of the present application provides a zinc-ion battery, including the deep eutectic electrolyte described in the first aspect of the present application or the deep eutectic electrolyte prepared by the method described in the second aspect of the present application. Thus, the zinc-ion battery has the advantages of high safety, excellent low-temperature performance, and good reversibility.

[0014] A third aspect of the present application provides an electrical device, including the zinc-ion battery described in the third aspect of the present application. Thus, the electrical device has a long service life. Description of the Drawings

[0015] Figure 1 Appearance photos of the deep eutectic electrolytes prepared in Examples 1 to 3 of the present application.

[0016] Figure 2 is the cyclic performance curve of the zinc-ion battery assembled in Example 1 of the present application.

[0017] Figure 3 is the cyclic performance curve of the zinc-ion battery assembled in Example 2 of the present application.

[0018] Figure 4It is the cyclic performance curve graph of the zinc-ion battery assembled in Example 3 of this application.

[0019] Figure 5 It is the cyclic performance curve graph of the zinc-ion battery assembled in Example 4 of this application.

[0020] Figure 6 It is the cyclic performance curve graph of the zinc-ion battery assembled in Example 5 of this application.

[0021] Figure 7 It is the cyclic performance curve graph of the zinc-ion battery assembled in Example 6 of this application.

[0022] Figure 8 It is the cyclic performance curve graph of the zinc-ion battery assembled in Comparative Example 1 of this application.

[0023] Figure 9 It is the cyclic performance curve graph of the zinc-ion battery assembled in Comparative Example 2 of this application. Detailed Description of the Invention

[0024] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0025] The first aspect of the present application provides a deep eutectic electrolyte, comprising: a zinc salt, an alcohol solvent, and deionized water; wherein, the molar ratio range of the zinc salt, the alcohol solvent, and the deionized water is 1:2-3:8-16. Among them, the alcohol solvent has a good antifreeze effect, which is beneficial to reducing the freezing point of the electrolyte and ensuring that the deep eutectic electrolyte does not freeze at low temperatures. Adding an appropriate amount of the alcohol solvent can ensure that the electrolyte does not freeze at low temperatures and the electrolyte has a certain ionic conductivity and transport ability; the role of deionized water is to increase the fluidity, conductivity, and ion transport efficiency of the deep eutectic electrolyte, thereby improving the kinetics of the zinc-ion battery. Too much water will cause too many side reactions during the cycling of the zinc-ion battery, resulting in poor stability and capacity retention rate of the zinc-ion battery. Therefore, preparing the deep eutectic electrolyte with the above ratio can make the deep eutectic electrolyte have a lower freezing point and still remain liquid at extremely low temperatures. Applying it to the zinc-ion battery can improve the low-temperature cycling performance of the battery.

[0026] In some embodiments, when there is one or two kinds of the alcohol solvents, the molar ratio range of the zinc salt, the alcohol solvent, and the deionized water is 1:2:8 to 16, for example, it can be 1:2:8, 1:2:12, or 1:2:16, etc. Specifically, when there is one kind of alcohol solvent, the molar ratio of the zinc salt, the alcohol solvent, and the deionized water can be 1:2:8, 1:2:12, or 1:2:16, etc.; when the alcohol solvent includes a first alcohol solvent and a second alcohol solvent, the molar ratio of the zinc salt, the first alcohol solvent, the second alcohol solvent, and the deionized water can be 1:1.5:0.5:8, 1:1.5:0.5:12, or 1:1.5:0.5:16, etc. Thus, it is beneficial for the reaction to be more complete and reduce raw material waste.

[0027] In some embodiments, when there are three kinds of the alcohol solvents, the molar ratio range of the zinc salt, the alcohol solvent, and the deionized water is 1:3:8 to 16, for example, it can be 1:3:8, 1:3:12, or 1:3:16, etc. Specifically, when the alcohol solvent includes a first alcohol solvent, a second alcohol solvent, and a third alcohol solvent, the molar ratio of the zinc salt, the first alcohol solvent, the second alcohol solvent, the third alcohol solvent, and the deionized water can be 1:1:1:1:8, 1:1:1:1:12, or 1:1:1:1:16, etc. Thus, it is beneficial for the reaction to be more complete and reduce raw material waste.

[0028] It can be understood that when the types of alcohol solvents are different, the dosage of the alcohol solvent also needs to be adjusted accordingly. Because the more hydroxyl groups the alcohol solvent contains, the greater the corresponding viscosity, the smaller the ionic conductivity, and the more difficult the ion transport. Therefore, more deionized water is needed to improve the ion transport efficiency of the deep eutectic electrolyte and ensure the normal cycling of the zinc ion battery.

[0029] In some embodiments, the zinc salt includes a sulfonic acid group zinc salt. The sulfonic acid group is a zincophilic group, and the zincophilic group can effectively inhibit the growth of zinc dendrites and improve the cycling stability of the zinc battery. This is because the zincophilic group can form a complex with zinc ions, reducing the activity of zinc ions in the electrolyte and thus inhibiting the growth of zinc dendrites. The zincophilic group can also improve the interfacial performance of the zinc battery and enhance the charge transfer kinetics. This is because the zincophilic group can form a stable interfacial layer on the surface of the zinc electrode, reducing the charge transfer impedance and improving the rate performance of the battery.

[0030] In some embodiments, the zinc salt includes at least one of zinc methanesulfonate, 1,2-ethanedisulfonic acid zinc, and zinc propane sulfonate. Thus, the material source is wide and the cost is low, and it can provide the ionic conductivity required for the deep eutectic electrolyte.

[0031] In some embodiments, the alcohol solvent includes at least one of ethylene glycol, glycerol, and xylitol. It can be understood that the alcohol solvent can be one of the above solvents, a mixture of two of the above solvents, or a mixture of three of the above solvents, that is, a single solvent, two solvents, or three solvents can all achieve battery cycling at low temperatures. Preparing a deep eutectic electrolyte using an alcohol solvent has the following advantages: (1) improving the performance of zinc-ion batteries in low-temperature environments. The alcohol solvent can inhibit the freezing of water, enabling the zinc-ion battery to maintain good ionic conductivity and stability at low temperatures. (2) Reducing the flammability of the deep eutectic electrolyte and improving safety. The alcohol solvent can inhibit the hydrogen bond interaction between water molecules, thereby reducing the flammability of the deep eutectic electrolyte and improving the safety of the zinc-ion battery in harsh environments. (3) Improving the electrode / deep eutectic electrolyte interface performance. The alcohol solvent can act synergistically with the polymer electrolyte to optimize the migration kinetics of zinc ions at the interface, thereby improving the rate performance of the battery.

[0032] The second aspect of this application proposes a method for preparing a deep eutectic electrolyte, including:

[0033] S1: Mix a zinc salt, an alcohol solvent, and deionized water to obtain a raw material mixture.

[0034] Among them, the mixing method of the zinc salt, the alcohol solvent, and deionized water is not specifically limited and can be flexibly selected according to specific needs. As an example, the zinc salt, the alcohol solvent, and deionized water can be weighed separately in proportion and then added to a container (such as a glass bottle) at one time.

[0035] S2: Heat the raw material mixture until it becomes clear, and let it stand for 6 h to 12 h to maintain stable clarity, obtaining a deep eutectic electrolyte.

[0036] In this step, the electrolyte is clear, and the fact that the electrolyte remains clear after standing for 6 h to 12 h indicates that the electrolyte is stable. The hydrogen bond interaction breaks the original lattice structure, thereby reducing the melting point of the entire system and forming a deep eutectic electrolyte.

[0037] It can be understood that when the heated raw material mixture is taken out of the oil bath and observed at room temperature for more than 12 hours, the deep eutectic electrolyte does not change and remains clear, indicating that the deep eutectic electrolyte is stable (i.e., the preparation is successful).

[0038] It should be noted that a Deep Eutectic Solvent (DES) is formed during the heating process. A deep eutectic solvent generally refers to a eutectic system formed by a hydrogen bond donor and a hydrogen bond acceptor through hydrogen bonding. Such a solvent is usually composed of two or more compounds, which form a eutectic under certain temperature and pressure conditions, resulting in a eutectic system with a melting point lower than that of any single component. The key principle for forming a deep eutectic solvent is hydrogen bonding. The hydrogen bond donor and the hydrogen bond acceptor interact with each other through hydrogen bonds, breaking the original lattice structure, thereby lowering the melting point of the entire system. In this application, a zinc salt is used as the hydrogen bond donor, and an alcohol solvent and water are used as the hydrogen bond acceptors. By heating, the hydrogen bond interaction breaks the original lattice structure, thereby lowering the melting point of the entire system.

[0039] In some embodiments, an oil bath is used to heat and dissolve the raw material mixture. Thus, it is convenient to control the temperature, the heating is uniform during the process, the operation is convenient, and it is beneficial to form a eutectic system.

[0040] In some embodiments, the heating temperature is 80°C to 100°C (such as 80°C, 85°C, 90°C, 95°C or 100°C, etc.), and the heating time is 2h to 6h (such as 2h, 3h, 4h, 5h or 6h, etc.). Thus, it is beneficial to make the reaction more complete, and then form a eutectic system.

[0041] The third aspect of this application proposes a zinc-ion battery, including the deep eutectic electrolyte described in the first aspect of this application or the deep eutectic electrolyte prepared by the method described in the second aspect of this application. Thus, this zinc-ion battery has advantages such as high safety, excellent low-temperature performance, and good reversibility.

[0042] In some embodiments, the zinc-ion battery can be normally cycled for charge and discharge at a current density of 0.5 A / g at an extremely low temperature of -40°C; in some specific examples, the zinc-ion battery can be stably cycled 1000 times. This shows that the zinc-ion battery prepared with the deep eutectic electrolyte described in this application still has high cycle performance and stability under low-temperature conditions, reducing the use and maintenance costs.

[0043] The fourth aspect of this application proposes an electrical device, including the zinc-ion battery described in the third aspect of this application. Thus, this electrical device has a long service life.

[0044] In some embodiments, the zinc-ion battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0045] Embodiments of the present application will be described in detail below.

[0046] Example 1

[0047] (1) Prepare a raw material mixture according to the molar ratio of zinc methanesulfonate (ZMSA): ethylene glycol (EG): glycerol (Gly): water (H2O) of 1:1.5:0.5:8;

[0048] (2) Add the weighed components into a glass bottle at one time, place it in an oil bath at 90 °C for heating and dissolution, and heat for 3 hours until the electrolyte becomes clear;

[0049] (3) Take out the clarified electrolyte from the oil bath, cool it at room temperature, observe it at room temperature for 12 hours. If the deep eutectic electrolyte remains stable and clear, the preparation is successful. For the photo of the prepared electrolyte, see Figure 1 .

[0050] Example 2

[0051] (1) Prepare a raw material mixture according to the molar ratio of zinc methanesulfonate (ZMSA): ethylene glycol (EG): glycerol (Gly): water (H2O) of 1:1.5:0.5:12;

[0052] (2) Add the weighed components into a glass bottle at one time, place it in an oil bath at 90 °C for heating and dissolution, and heat for 3 hours until the electrolyte becomes clear;

[0053] (3) Take out the clarified electrolyte from the oil bath, cool it at room temperature, observe it at room temperature for 12 hours. If the deep eutectic electrolyte remains stable and clear, the preparation is successful. For the photo of the prepared electrolyte, see Figure 1 .

[0054] Example 3

[0055] (1) Prepare a raw material mixture according to the molar ratio of zinc methanesulfonate (ZMSA): ethylene glycol (EG): glycerol (Gly): water (H2O) of 1:1.5:0.5:16;

[0056] (2) Add the weighed components into a glass bottle at one time, place it in an oil bath at 90 °C for heating and dissolution, and heat for 3 hours until the electrolyte becomes clear;

[0057] (3) Take out the clarified electrolyte from the oil bath and cool it at room temperature. Observe it for 12 hours at room temperature. If the deep eutectic electrolyte remains stable and clear, the preparation is successful. The photo of the prepared electrolyte can be seen in Figure 1 .

[0058] Example 4

[0059] (1) Prepare a raw material mixture according to the molar ratio of zinc methanesulfonate (ZMSA): ethylene glycol (EG): water (H2O) of 1:2:8;

[0060] (2) Add the weighed components into a glass bottle at one time, place it in an oil bath at 100 °C and heat it for dissolution for 2 hours until the electrolyte becomes clear;

[0061] (3) Take out the clarified electrolyte from the oil bath and cool it at room temperature. Observe it for 12 hours at room temperature. If the deep eutectic electrolyte remains stable and clear, the preparation is successful.

[0062] Example 5

[0063] (1) Prepare a raw material mixture according to the molar ratio of zinc methanesulfonate (ZMSA): glycerol (Gly): water (H2O) of 1:2:8;

[0064] (2) Add the weighed components into a glass bottle at one time, place it in an oil bath at 80 °C and heat it for dissolution for 6 hours until the electrolyte becomes clear;

[0065] (3) Take out the clarified electrolyte from the oil bath and cool it at room temperature. Observe it for 12 hours at room temperature. If the deep eutectic electrolyte remains stable and clear, the preparation is successful.

[0066] Example 6

[0067] (1) Prepare a raw material mixture according to the molar ratio of zinc methanesulfonate (ZMSA): ethylene glycol (EG): glycerol (Gly): xylitol (Xly): water (H2O) of 1:1:1:1:12;

[0068] (2) Add the weighed components into a glass bottle at one time, place it in an oil bath at 90 °C and heat it for dissolution for 3 hours until the electrolyte becomes clear;

[0069] (3) Take out the clarified electrolyte from the oil bath and cool it at room temperature. Observe it for 12 hours at room temperature. If the deep eutectic electrolyte remains stable and clear, the preparation is successful.

[0070] Comparative Example 1

[0071] Prepare the electrolyte according to the molar ratio of zinc methanesulfonate (ZMSA): ethylene glycol (EG): glycerol (Gly): water (H2O) of 1:1:1:16.

[0072] Comparative Example 2

[0073] Prepare the electrolyte according to the molar ratio of zinc methanesulfonate (ZMSA): water (H2O) of 1:16.

[0074] Test method:

[0075] At 25 °C, use an MSK-T10 tablet press to cut the zinc foil into a circular piece with a diameter of 16 mm as the negative electrode, and the V2O5 carbon sheet as the positive electrode, cut into a small circular piece of 2.01 cm 2 Use a glass fiber as the separator membrane, inject 80 μl of the above-prepared electrolyte to form a button battery. The positive and negative electrode cases of the battery use CR2032, the gasket has a diameter of 16 mm and a thickness of 1 mm, the diameter of the spring piece is 16 mm, and it is assembled using an MSK-100 pressure-controlled electric button battery sealing machine. The assembled symmetric battery is subjected to a cycle life test using a Neware-CT-4008-10V1A-S1-F workstation, with a current density of 0.5 A / g. Record the cycle time when the symmetric battery starts to decay, which is the cycle life; the capacity retention rate = capacity after 1000 cycles / initial capacity × 100%. The test results of Examples 1 to 6 and Comparative Examples 1 to 2 are as follows Figures 2 to 9 shown.

[0076] The test results are as follows:

[0077] Table 1 Test Results

[0078] Test temperature (°C) Capacity retention rate (%) after 1000 cycles Example 1 -40 92.6 Example 2 -40 58.8 Example 3 -40 41.6 Example 4 -40 27.2 Example 5 -40 53.1 Example 6 -40 27.9 Comparative Example 1 25 12.9 Comparative Example 2 25 3.8

[0079] From Table 1 and Figures 1 to 9 it can be seen that compared with the zinc-ion battery assembled with a common electrolyte tested at room temperature, the zinc-ion battery prepared with the deep eutectic electrolyte of the present application has a higher capacity retention rate at low temperature. Especially from Example 1, it can be seen that the zinc-ion battery assembled with the deep eutectic electrolyte of this ratio can stably cycle at low temperature, and the capacity retention rate is as high as 92.6%.

[0080] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0081] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A deep eutectic electrolyte, characterized in that: include: Zinc salt, alcohol solvent, deionized water; Wherein, the molar ratio of the zinc salt, the alcohol solvent and the deionized water is in the range of 1:2-3:8-16.

2. The deep eutectic electrolyte according to claim 1, characterized in that When the alcohol solvent is one or two, the molar ratio of the zinc salt, the alcohol solvent, and the deionized water is in the range of 1:2:8 to 16; When there are three kinds of alcohol solvents, the molar ratio of the zinc salt, the alcohol solvent and the deionized water is in the range of 1:3:8-16.

3. The deep eutectic electrolyte according to claim 1, characterized in that The zinc salt includes a sulfonic acid zinc salt.

4. The deep eutectic electrolyte according to claim 1 or 3, characterized in that The zinc salt includes at least one of zinc methane sulfonate, zinc 1,2-ethane disulfonate, and zinc propane sulfonate.

5. The deep eutectic electrolyte according to claim 1, characterized in that The alcohol solvent includes at least one of ethylene glycol, glycerol and xylitol.

6. A method for preparing the deep eutectic electrolyte according to any one of claims 1 to 5, characterized in that: include: Mixing zinc salt, alcohol solvent and deionized water to obtain a raw material mixture; The raw material mixture is heated until it is clear, and allowed to stand for 6 hours to 12 hours to maintain stable clarity, thereby obtaining a deep eutectic electrolyte.

7. The method according to claim 6, characterized in that The raw material mixture was heated and dissolved using an oil bath.

8. The method according to claim 7, characterized in that The heating temperature is 80° C. to 100° C., and the heating time is 2 h to 6 h.

9. A zinc ion battery, characterized in that: The invention comprises the deep eutectic electrolyte according to any one of claims 1 to 5 or the deep eutectic electrolyte prepared by the method according to any one of claims 6 to 8.

10. An electrical device, characterized in that: Including the zinc ion battery as described in claim 9.

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