Electrolyte, battery and electrical equipment

Abstract

This application provides an electrolyte, a battery, and an electrical device. The electrolyte comprises water, an electrolyte salt, and an additive. The additive has a general structural formula comprising R1-O-R-O-R2; wherein R is selected from an alkylene, alkenylene, or alkynylene group; and R1 and R2 are independently selected from alkyl groups. The electrolyte provided in the embodiments of this application can effectively improve the coulombic efficiency and cycle performance of zinc-ion batteries.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to electrolytes, batteries and electrical equipment. Background Art

[0002] Currently, aqueous electrolytes are commonly used in zinc-ion batteries, significantly reducing their production costs and difficulty. They are also environmentally friendly and highly safe, offering promising potential. However, issues such as severe interfacial side reactions at the negative electrode, uneven ion deposition / stripping, and electrolyte decomposition contribute to low coulombic efficiency and poor cycling performance, hindering their further development and commercialization. Summary of the Invention

[0003] In view of this, the embodiments of the present application provide an electrolyte, a battery, and an electrical device. The electrolyte provided in the embodiments of the present application can effectively improve the coulombic efficiency and cycle performance of zinc ion batteries.

[0004] In a first aspect, an embodiment of the present application provides an electrolyte comprising water, an electrolyte salt, and an additive, wherein the general structural formula of the additive comprises R1-ORO-R2; wherein R is selected from an alkylene group, an alkenylene group, or an alkynylene group; and R1 and R2 are independently selected from an alkyl group.

[0005] When the electrolyte provided by the embodiment of the present application is applied in a zinc ion battery, during the charging process of the battery, the above-mentioned additive can be quickly adsorbed at the interface of the positive electrode and the negative electrode, and participates in the formation of a double electric layer, and the aliphatic hydrocarbon group in R1-ORO-R2 has a hydrophobic property, which is beneficial for repelling the water molecules in the electrolyte on the side surface of the double electric layer away from the negative electrode, and continuously suppressing its direct contact with the negative electrode through the double electric layer structure, suppressing the decomposition of water molecules and its side reaction with the negative electrode, thereby effectively improving the coulomb efficiency of the battery. In addition, the double electric layer formed by the above-mentioned additive is beneficial for the surface reduction of anions at the negative electrode to form a solid electrolyte interface film, which improves the interface stability of the electrode. Moreover, during the charging process of the battery cycle, zinc ions can be rapidly adsorbed by the above-mentioned additive molecules, thereby accelerating the decoupling of zinc ions from the coordinated water, and can induce zinc ions to be uniformly deposited on the surface of the negative electrode, reducing dendrites and loose porous structures, thereby further improving the coulomb efficiency of the battery, and improving the cycle capacity retention rate of the battery.

[0006] In some embodiments of the present application, R1 and R2 are respectively selected from alkyl groups with 1-6 carbon atoms; and R is selected from any one of an alkylene group with 3 or more carbon atoms, an alkenylene group with 3 or more carbon atoms, and an alkynylene group with 3 or more carbon atoms.

[0007] In some embodiments of the present application, R is selected from any one of an alkylene group having 3 to 6 carbon atoms, an alkenylene group having 3 to 6 carbon atoms, and an alkynylene group having 3 to 6 carbon atoms.

[0008] In some embodiments of the present application, the additive includes one or more of 1,3-dimethoxypropane, 1,4-dimethoxybutane, 1,5-dimethoxypentane, and 1,6-dimethoxyhexane.

[0009] In some embodiments of the present application, the additive accounts for 5%-15% by mass in the electrolyte.

[0010] In some embodiments of the present application, the electrolyte salt includes one or more of Zn(CF3SO3)2, ZnSO4, and Zn(CH3OO)2.

[0011] A second aspect of the present invention provides a battery comprising the aforementioned electrolyte provided in the present invention. In some embodiments of the present invention, the battery is a zinc-ion battery. Due to the use of the electrolyte provided in the present invention, the battery has high coulombic efficiency and excellent cycle performance.

[0012] In a third aspect, embodiments of the present application provide an electrical device comprising a battery provided in embodiments of the present application. In some embodiments of the present application, the electrical device includes electronic components, and the battery is used to power the electronic components. Due to the use of the battery provided in embodiments of the present application for powering such an electrical device, the market prospects for such an electrical device are promising.

[0013] In some embodiments of the present application, the above-mentioned electrical equipment includes but is not limited to vehicles, or 3C electronic consumer products such as mobile phones, laptops, tablets, smart watches, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The capacity retention rate-cycle number curves of the Zn||V2O5 batteries of Example 3, Example 4 and Comparative Example 1 of the present application are summarized in FIG. DETAILED DESCRIPTION

[0015] The production cost of zinc-ion batteries using aqueous electrolytes is low, the requirements for the production environment are relatively loose, and they do not require the use of large amounts of organic solvents, making them environmentally friendly. During the charging process of zinc-ion batteries, current flows from the negative electrode to the positive electrode, at which time the material of the positive electrode releases Zn 2+ and electrons, Zn 2+ Conducted to the negative electrode through the electrolyte and deposited on the negative electrode surface. In aqueous electrolyte, Zn 2+ It is easy to have side reactions with water molecules, for example, Zn 2+ It is easy to form strong coordination bonds with water molecules, causing Zn 2+The desolvation kinetics of the ZnO2 are slow, and the large amount of water molecules released during desolvation can come into contact with the zinc metal anode, causing side reactions. Furthermore, it can easily lead to uneven deposition of zinc metal on the anode surface, such as the formation of a loose porous structure and dendrites, which can lead to reduced coulombic efficiency and poor cycling performance.

[0016] In order to solve the above technical problems, an embodiment of the present application provides an electrolyte, including water, an electrolyte salt and an additive, the general structural formula of the additive includes R1-ORO-R2; wherein R is selected from an alkylene group, an alkenylene group or an alkynylene group; R1 and R2 are independently selected from an alkyl group.

[0017] It is understandable that an electrical double layer (EDL) structure is generated at the interface between the positive and negative electrodes of an aqueous zinc-ion battery during the charge and discharge process. Especially during the first charge of an aqueous zinc-ion battery, the electrical double layer also affects the formation of a solid electrolyte interface (SEI) film on the surface of the negative electrode. During the charge and discharge process of a zinc-ion battery, a certain potential difference is generated at the interface between the positive and negative electrodes, forming a region with positive and negative charges at the interface. This region is the electrical double layer.

[0018] When the electrolyte provided by the embodiment of the present application is applied in a zinc ion battery, during the charging process of the battery, the above-mentioned additives can be quickly adsorbed at the interface between the positive electrode and the negative electrode, participating in the formation of a double electric layer, and the aliphatic hydrocarbon group in R1-ORO-R2 has a hydrophobic property, which is beneficial for repelling water molecules in the electrolyte on the surface of the double electric layer away from the negative electrode, continuously inhibiting them from passing through the double electric layer structure and directly contacting the negative electrode, inhibiting the decomposition of water molecules and their side reactions with the negative electrode, thereby effectively improving the coulombic efficiency of the battery. In addition, the double electric layer formed by the participation of the above-mentioned additives is beneficial for the reduction of anions on the surface of the negative electrode to form an SEI film, thereby improving the interface stability of the electrode.

[0019] Furthermore, during the charging process of the battery cycle, zinc ions can be quickly adsorbed by the above-mentioned additive molecules, thereby accelerating the removal of coordinated water from zinc ions and inducing zinc ions to be evenly deposited on the surface of the negative electrode, reducing dendrites and loose porous structures, thereby further improving the coulombic efficiency of the battery and improving the battery's cycle capacity retention rate.

[0020] In some embodiments of the present application, R1 and R2 are each selected from an alkyl group having 1 to 6 carbon atoms. This further enhances the hydrophobic properties of the additive. Specifically, R1 and R2 can each independently be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a dimethylpropyl group, an n-pentyl group, an n-hexyl group, or the like. The number of carbon atoms in R1 and R2 can be, for example, 1, 2, 3, 4, 5, or 6.

[0021] In some embodiments of the present application, R is selected from an alkylene group having less than or equal to 6 carbon atoms, an alkenylene group having less than or equal to 6 carbon atoms, or an alkynylene group having less than or equal to 6 carbon atoms. Specifically, R can be an alkylene group having 1, 2, 3, 4, 5, or 6 carbon atoms; or, R can be an alkenylene group having 2, 3, 4, 5, or 6 carbon atoms; or, R can be an alkynylene group having 2, 3, 4, 5, or 6 carbon atoms.

[0022] In some embodiments of the present application, R is selected from any one of an alkylene group having a carbon number greater than or equal to 3, an alkenylene group having a carbon number greater than or equal to 3, and an alkynylene group having a carbon number greater than or equal to 3. The long non-polar carbon chain weakens the interaction between the additive molecules and the water molecules, making the additive more easily aggregated and stabilized in a non-polar environment, thereby improving its overall hydrophobicity. In some embodiments of the present application, R is selected from an alkylene group having a carbon number of 3-6, an alkenylene group having a carbon number of 3-6, or an alkynylene group having a carbon number of 3-6. Controlling the number of carbon atoms in R to be 3-6 can make R have both better hydrophobicity and better steric hindrance, and can be more rapidly adsorbed at the interface between the negative electrode and the positive electrode, which is more conducive to repelling water molecules from the surface of the double layer facing away from the negative electrode. In this way, the additive molecules can exert better hydrophobic properties, and the steric hindrance of the molecules is small, which is conducive to adsorption at the interface between the positive electrode and the negative electrode to form a double layer. Specifically, R can be a linear alkylene group, a linear alkenylene group, or a linear alkynylene group; for example, R can be a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a vinylene group, a propenylene group, a butenylene group, an ethynylene group, a propynylene group, a butynylene group, etc. When the number of carbon atoms in R is controlled within the above range, the coulombic efficiency of the battery will be further improved as the number of carbon atoms increases.

[0023] In some embodiments, R is selected from an alkylene group having 1 to 6 carbon atoms. In some specific embodiments, R is selected from an alkylene group having 3 to 6 carbon atoms. This improves the hydrophobicity of the additive molecule and is more conducive to improving the coulombic efficiency of the zinc-ion battery.

[0024] In some embodiments of the present application, the additive includes one or more of 1,3-dimethoxypropane, 1,4-dimethoxybutane, 1,5-dimethoxypentane, and 1,6-dimethoxyhexane. These additives have a more significant effect on improving battery performance and can further improve the cycle performance of the battery.

[0025] In some embodiments of the present application, the mass proportion of the additive in the electrolyte is 0.01%-99.9%. In some specific embodiments, the mass proportion of the additive in the electrolyte is 5%-15%. In this way, during the charge and discharge process of the battery, a stable double layer can be formed at the interface between the negative electrode and the positive electrode, which improves the kinetics of zinc ion desolvation of water and inhibits the side reaction between water and the negative electrode, thereby improving the coulombic efficiency of the battery. In addition, by controlling the content of the additive within the above range, some additive molecules will be free in the electrolyte during the charge and discharge cycle of the battery, which can coordinate with water molecules and / or zinc ions. Coordination with zinc ions can promote the dehydration of zinc ions and further optimize the cycle performance of the battery; the coordination of additive molecules with water molecules can inhibit the activity of water, thereby inhibiting side reactions, and lowering the freezing point of water to optimize the low-temperature performance of the battery. Specifically, the mass proportion of R1-ORO-R2 in the electrolyte can be, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0026] In some embodiments of the present application, the electrolyte is used in a zinc ion battery, and the electrolyte includes a zinc ion electrolyte salt, which can be any electrolyte known in the art for use in aqueous zinc ion batteries. In some embodiments, the electrolyte salt includes, but is not limited to, one or more of Zn(CF3SO3)2, ZnSO4, and Zn(CH3OO)2.

[0027] In some embodiments of the present application, the concentration of the electrolyte in the electrolyte is 0.01mol / kg-50mol / kg. In some specific embodiments, the concentration of the electrolyte in the electrolyte is 1mol / kg-5mol / kg. In this way, it is beneficial to the performance of the battery. Specifically, the concentration of the electrolyte in the electrolyte can be, for example, 0.01mol / kg, 0.05mol / kg, 0.1mol / kg, 1mol / kg, 2mol / kg, 3mol / kg, 4mol / kg, 5mol / kg, 8mol / kg, 10mol / kg, 15mol / kg, 20mol / kg, 25mol / kg, 30mol / kg, 35mol / kg, 40mol / kg, 45mol / kg, 50mol / kg, etc.

[0028] In the embodiment of the present application, the electrolyte may further include other additives for aqueous electrolytes known in the art.

[0029] The present invention also provides a battery comprising the aforementioned electrolyte provided in the present invention. Due to the use of the electrolyte provided in the present invention, the battery has a high coulombic efficiency and excellent cycle performance.

[0030] In some embodiments of the present application, the battery is a zinc ion battery.

[0031] In some embodiments of the present application, the battery includes a positive electrode, a negative electrode, an electrolyte and a separator positioned between the positive electrode and the negative electrode, and the negative electrode is a zinc metal negative electrode. Specifically, the positive electrode can be any known positive electrode suitable for aqueous zinc ion batteries, and the zinc metal negative electrode can be any known zinc metal negative electrode suitable for aqueous zinc ion batteries. In the embodiments of the present application, the separator can be any separator known in the art that is suitable for aqueous zinc ion batteries, for example, a glass fiber separator.

[0032] In some embodiments of the present application, an electrical double layer is formed between the positive and negative electrodes, and the electrical double layer includes an additive. Specifically, the electrical double layer may be formed between the positive and negative electrodes during the battery's charge-discharge cycle or formation process. In situ Raman spectroscopy can be used to characterize the presence of the electrical double layer.

[0033] The present application also provides an electrical device comprising the battery provided in the present application. In some embodiments of the present application, the electrical device includes electronic components, and the battery is used to power the electronic components. Due to the use of the battery provided in the present application, the market prospects of such an electrical device are promising.

[0034] In some embodiments of the present application, the above-mentioned electrical equipment includes but is not limited to vehicles, or 3C electronic consumer products such as mobile phones, laptops, tablets, smart watches, etc.

[0035] The technical solution of this application is further illustrated below with multiple embodiments.

[0036] Example 1

[0037] An electrolyte consists of water, an electrolyte (specifically zinc sulfate), and an additive (specifically 1,3-dimethoxypropane), wherein the electrolyte concentration is 1 mol / kg and the mass proportion of 1,3-dimethoxypropane in the electrolyte is 10%.

[0038] Example 2

[0039] An electrolyte consists of water, an electrolyte (specifically zinc sulfate), and an additive (specifically 1,4-dimethoxybutane), wherein the electrolyte concentration is 1 mol / kg and the mass proportion of 1,4-dimethoxybutane in the electrolyte is 1%.

[0040] Example 3

[0041] An electrolyte consists of water, an electrolyte (specifically zinc sulfate), and an additive (specifically 1,5-dimethoxypentane), wherein the electrolyte concentration is 1 mol / kg and the mass proportion of 1,5-dimethoxypentane in the electrolyte is 5%.

[0042] Example 4

[0043] An electrolyte consists of water, an electrolyte (specifically zinc sulfate), and an additive (specifically 1,6-dimethoxyhexane), wherein the electrolyte concentration is 1 mol / kg and the mass proportion of 1,6-dimethoxyhexane in the electrolyte is 10%.

[0044] Example 5

[0045] An electrolyte consists of water, an electrolyte (specifically zinc sulfate), and an additive (specifically 1,6-dimethoxyhexane), wherein the electrolyte concentration is 1 mol / kg and the mass proportion of 1,6-dimethoxyhexane in the electrolyte is 5%.

[0046] Example 6

[0047] An electrolyte consists of water, an electrolyte (specifically zinc sulfate), and an additive (specifically 1,6-dimethoxyhexane), wherein the electrolyte concentration is 1 mol / kg and the mass proportion of 1,6-dimethoxyhexane in the electrolyte is 15%.

[0048] In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples are provided.

[0049] Comparative Example 1

[0050] An electrolyte solution consists of water and an electrolyte (specifically zinc sulfate), and the electrolyte concentration is 1 mol / kg.

[0051] Comparative Example 2

[0052] An electrolyte consists of water, an electrolyte (specifically zinc sulfate) and ethylene glycol dimethyl ether, wherein the electrolyte concentration is 1 mol / kg and the mass proportion of ethylene glycol dimethyl ether in the electrolyte is 10%.

[0053] Performance Testing

[0054] (1) Coulomb efficiency test

[0055] Using copper foil as the positive electrode and zinc foil with a thickness of 50 μm as the negative electrode, the electrolytes of each embodiment and comparative example were respectively assembled into Zn||Cu half-cells; the coulombic efficiency of each half-cell was tested as follows:

[0056] Electrode Preparation: A 50 μm-thick Zn metal sheet was cut into a 13 mm diameter sheet and used as the negative electrode in the half-cell. A 9 μm-thick Cu foil was cut into a 16 mm diameter sheet and used as the positive electrode in the half-cell. A glass fiber separator (GF-A) was cut into a 19 mm diameter sheet and used as the separator in the half-cell.

[0057] Test: The assembled Zn||Cu half-cell was tested for zinc metal coulombic efficiency at room temperature (25°C).2 After the current is discharged to 0.005V, it is then discharged at 1mA / cm 2 The battery was charged to 1V with a current of 100. This was considered one cycle, and 100 cycles were repeated. The data after each cycle was recorded using a blue light tester (model CT3002A). The coulombic efficiency of the 100 cycles was averaged to obtain the average coulombic efficiency, and the results are summarized in Table 1.

[0058] (2) Cyclic performance test

[0059] Using V2O5 as the positive electrode and a zinc foil with a thickness of 50 μm as the negative electrode, the electrolytes of each embodiment and comparative example were assembled into Zn||V2O5 full batteries, and the cycle performance tests were carried out as follows:

[0060] Preparation is as follows: 50 μm thick Zn metal sheet was cut into 13 mm diameter sheets and used as half-cell negative electrode, with active material loading of 2 mg / cm 2 V2O5 was used as the positive electrode. Glass fiber separator (GF-A) was cut into 19 mm diameter and used as the separator of the half cell.

[0061] Test: The assembled Zn||V2O5 battery was charged from the open circuit potential to 1.8V at a rate of 0.1C at room temperature (25°C), and then discharged to 0.5V at a rate of 0.1C. This was considered a cycle, and the battery was activated after 3 cycles. Subsequently, the charge and discharge current density was increased, and the battery was charged from the open circuit potential to 1.8V at a rate of 1 / 3C, and then discharged to 0.5V at a rate of 1 / 3C. This was considered a cycle, and the capacity retention rate after 100 cycles was calculated. The data after each cycle was recorded using a blue electric tester (model CT3002A). The results are shown in Table 1; among them, Figure 1 The capacity retention rate-cycle number curves of the Zn||V2O5 batteries of Example 3, Example 4 and Comparative Example 1 of the present application are summarized in FIG. Wherein, capacity retention rate = discharge capacity at the 100th cycle / discharge capacity at the 1st cycle * 100%.

[0062] Table 1

[0063] Case Average Coulombic efficiency 100-cycle capacity retention rate Example 1 93.6％ 84.5％ Example 2 97.5％ 85.9％ Example 3 98.3％ 93.1％ Example 4 99.9％ 94.2％ Example 5 99.4％ 91.7％ Example 6 99.1％ 89.6％ Comparative Example 1 84.8％ 70.0％ Comparative Example 2 90.8％ 82.1％

[0064] As can be seen from the data in Table 1, the electrolyte provided in the examples of the present application can effectively improve the coulombic efficiency of aqueous zinc ion batteries and effectively optimize the cycle capacity retention rate of aqueous zinc ion batteries. Further, by comparing the data of Example 1 and Example 4, it can be found that within the scope further suggested by the present application, when the number of carbon atoms of R is further increased, it is more conducive to improving the coulombic efficiency of aqueous zinc ion batteries.

Claims

1. An electrolyte, characterized in that: The invention comprises water, an electrolyte salt and an additive, wherein the additive has a general structural formula of R1-ORO-R2; wherein R is selected from an alkylene group, an alkenylene group or an alkynylene group having a carbon number greater than or equal to 4; and R1 and R2 are independently selected from an alkyl group; The additive accounts for 5% to 15% by mass in the electrolyte.

2. The electrolyte according to claim 1, characterized in that The R1 and R2 are each selected from an alkyl group having 1 to 6 carbon atoms.

3. The electrolyte according to claim 2, characterized in that The R is selected from any one of an alkylene group having 4 to 6 carbon atoms, an alkenylene group having 4 to 6 carbon atoms, and an alkynylene group having 4 to 6 carbon atoms.

4. The electrolyte according to claim 1, characterized in that The additive includes one or more of 1,4-dimethoxybutane, 1,5-dimethoxypentane, and 1,6-dimethoxyhexane.

5. The electrolyte according to any one of claims 1 to 4, characterized in that The electrolyte salt includes one or more of Zn(CF3SO3)2, ZnSO4, and Zn(CH3OO)2.

6. A battery, characterized in that: The electrolyte comprises the electrolyte according to any one of claims 1 to 5.

7. The battery according to claim 6, wherein It also includes a positive electrode, a negative electrode and a separator located between the positive electrode and the negative electrode; the material of the negative electrode includes zinc metal.

8. The battery according to claim 7, characterized in that An electric double layer is formed between the positive electrode and the negative electrode, and the electric double layer includes the additive.

9. An electrical device, characterized in that: Comprising the battery according to any one of claims 6 to 8.

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