Water-based sodium-ion battery electrolyte, preparation method and application thereof, and water-based sodium-ion battery

Abstract

The invention provides an aqueous sodium-ion battery electrolyte, a preparation method and application thereof, and an aqueous sodium-ion battery. The aqueous sodium-ion battery electrolyte comprises electrolyte salt and water, wherein positive ions of the electrolyte salt are sodium ions and quaternary ammonium salt positive ions, and negative ions of the electrolyte salt are perchlorate ions; the quaternary ammonium salt cations are asymmetric quaternary ammonium salt cations. The aqueous sodium-ion battery electrolyte contains asymmetric alkyl perchlorate quaternary ammonium salt, the quaternary ammonium salt is used as a large-size cation, so that the relative proportion of water is reduced, the asymmetric structure can endow the aqueous sodium-ion battery electrolyte with higher polarity and water solvation action capability, and an electrochemical window is broadened more efficiently; and the irregularity of the molecules also endows the electrolyte with weaker crystallization tendency, so that the stability of the electrolyte and the corresponding battery cycle is improved.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to an aqueous sodium-ion battery electrolyte, its preparation method and application, and an aqueous sodium-ion battery. Background Technology

[0002] With the scaling up of renewable energy and the widespread adoption of electric vehicles, rechargeable batteries have become a key energy storage technology. Commercial lithium-ion batteries are limited by lithium resource shortages, high costs, and the flammability of organic electrolytes, making it difficult to meet the safety and economic requirements of large-scale energy storage. Against this backdrop, aqueous sodium-ion batteries, with their inherent safety, abundant raw materials, and low cost, have become a promising alternative. However, this system faces a fundamental bottleneck: the theoretical decomposition voltage of water is only 1.2 V, resulting in a narrow electrochemical window that severely restricts the battery's operating voltage and energy density. To overcome this limitation, the academic community has proposed a high-concentration salt electrolyte strategy. This strategy significantly reduces the number of free water molecules in the system, thereby effectively suppressing water activity and decomposition reactions, and widening the aqueous electrolyte window to over 2 V.

[0003] Achieving high concentrations requires electrolyte salts with extremely high water solubility. Sodium perchlorate has been proven to be a suitable base solute for constructing such electrolytes due to this property. However, studies have found that sodium perchlorate alone does not provide ideal capacity utilization and cycle stability for some high-performance sodium electrode materials. Simply using high-concentration sodium perchlorate as the electrolyte still faces challenges due to insufficient interfacial stability, failing to guarantee good long-term cycle performance. Developing an efficient and stable electrolyte system remains a key technological challenge for advancing aqueous sodium-ion batteries. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an aqueous sodium-ion battery electrolyte, its preparation method and application, and an aqueous sodium-ion battery.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an aqueous sodium-ion battery electrolyte, comprising an electrolyte salt and water; wherein the cations of the electrolyte salt are sodium ions and quaternary ammonium salt cations, and the anions are perchlorate ions;

[0007] The quaternary ammonium salt cation is an asymmetric quaternary ammonium salt cation.

[0008] Preferably, the quaternary ammonium salt cation contains 1 to 8 carbon atoms.

[0009] Preferably, the quaternary ammonium salt cation contains 1 to 4 carbon atoms.

[0010] Preferably, the asymmetric quaternary ammonium salt cation includes at least one of triethylmethylammonium ion, n-propyltrimethylammonium ion, isopropyltrimethylammonium ion, dimethyldiethylammonium ion, methyldiethyln-propylammonium ion, trimethyln-butylammonium ion, ethyltripropylammonium ion, diethyldin-propylammonium ion, methyltrin-butylammonium ion, isopropyltriethylammonium ion, dimethylethyln-propylammonium ion, and n-butyltriethylammonium ion.

[0011] Preferably, the electrolyte salt includes sodium perchlorate and a perchlorate quaternary ammonium salt;

[0012] The perchlorate quaternary ammonium salt includes at least one of triethylmethyl ammonium perchlorate, n-propyltrimethyl ammonium perchlorate, isopropyltrimethyl ammonium perchlorate, dimethyldiethyl ammonium perchlorate, methyldiethyln-propyl ammonium perchlorate, trimethyln-butyl ammonium perchlorate, ethyltripropyl ammonium perchlorate, diethyldi-n-propyl ammonium perchlorate, methyltri-n-butyl ammonium perchlorate, isopropyltriethyl ammonium perchlorate, dimethylethyln-propyl ammonium perchlorate, and n-butyltriethyl ammonium perchlorate.

[0013] Preferably, the concentration of perchlorate ions in the electrolyte is 8~25 mol / kg, the concentration of sodium ions is 5~18 mol / kg, and the concentration of quaternary ammonium salt cations is 1~12 mol / kg.

[0014] Secondly, the present invention also provides a method for preparing the aqueous sodium-ion battery electrolyte, comprising the following steps:

[0015] Sodium perchlorate and perchlorate quaternary ammonium salt are added to water and dissolved to obtain the product.

[0016] Thirdly, the present invention also provides the application of the aqueous sodium-ion battery electrolyte or the aqueous sodium-ion battery electrolyte prepared by the preparation method described above in the preparation of aqueous sodium-ion batteries.

[0017] Fourthly, the present invention also provides an aqueous sodium-ion battery, comprising an electrolyte, wherein the electrolyte comprises the aqueous sodium-ion battery electrolyte described above or the aqueous sodium-ion battery electrolyte prepared by the preparation method described above.

[0018] The aqueous sodium-ion battery electrolyte, its preparation method, and its application, as well as the aqueous sodium-ion battery of the present invention, have the following advantages over the prior art:

[0019] The aqueous sodium-ion battery electrolyte of the present invention contains an asymmetric alkyl perchlorate quaternary ammonium salt. As a large-sized cation, the quaternary ammonium salt itself reduces the relative proportion of water. The asymmetric structure endows it with stronger polarity and water solubility, and more efficiently broadens the electrochemical window. In addition, the irregularity of the molecule also gives it a weaker tendency to crystallize, thereby improving the stability of the electrolyte and the corresponding battery cycle. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This refers to the electrochemical window of the electrolyte in Example 4;

[0022] Figure 2 The cycling performance curves of the aqueous sodium-ion battery assembled with the electrolyte in Example 4 are shown.

[0023] Figure 3 The charge-discharge curves of the aqueous sodium-ion battery assembled with the electrolyte in Example 4 are shown after the 500th cycle. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0026] This application provides an aqueous sodium-ion battery electrolyte, comprising an electrolyte salt and water; wherein the cations of the electrolyte salt are sodium ions and quaternary ammonium salt cations, and the anion is perchlorate ions;

[0027] Quaternary ammonium cations are asymmetric quaternary ammonium cations, meaning that at least one alkyl group in the quaternary ammonium cation is different from the other alkyl groups.

[0028] In this invention, the electrolyte for an aqueous sodium-ion battery contains sodium ions and quaternary ammonium salt cations, and perchlorate ions as anions. Specifically, the electrolyte salt includes sodium perchlorate and perchlorate quaternary ammonium salt. The perchlorate quaternary ammonium salt is an asymmetric structure, which has the following advantages: the non-uniform charge distribution endows it with stronger polarity and solvation ability, significantly improving its ability to bind free water molecules and further broadening the electrochemical window; in addition, the irregularity of the molecules gives it a weaker tendency to crystallize, improving the cycle stability of the electrolyte and the corresponding battery (the better cycle performance is attributed to the more complex composition of the asymmetric quaternary ammonium salt, with more diverse decomposition pathways and products, which help form a better interface and ensure cycle performance).

[0029] In some embodiments, the number of carbon atoms in the quaternary ammonium salt cation is 1 to 8. Preferably, the number of carbon atoms in the quaternary ammonium salt cation is 1 to 4. Short chains generally have higher solubility, and the hydrophobic effect is more obvious when there are more than 8 carbon atoms.

[0030] In some embodiments, the asymmetric quaternary ammonium salt cation includes at least one of triethylmethylammonium ion, n-propyltrimethylammonium ion, isopropyltrimethylammonium ion, dimethyldiethylammonium ion, methyldiethyln-propylammonium ion, trimethyln-butylammonium ion, ethyltripropylammonium ion, diethyldin-propylammonium ion, methyltrin-butylammonium ion, isopropyltriethylammonium ion, dimethylethyln-propylammonium ion, and n-butyltriethylammonium ion.

[0031] In some embodiments, the electrolyte salt includes sodium perchlorate and perchlorate quaternary ammonium salt;

[0032] The perchlorate quaternary ammonium salt includes at least one of triethylmethyl ammonium perchlorate, n-propyltrimethyl ammonium perchlorate, isopropyltrimethyl ammonium perchlorate, dimethyldiethylammonium perchlorate, methyldiethyln-propylammonium perchlorate, trimethyln-butylammonium perchlorate, ethyltripropylammonium perchlorate, diethyldi-n-propylammonium perchlorate, methyltri-n-butylammonium perchlorate, isopropyltriethylammonium perchlorate, dimethylethyln-propylammonium perchlorate, and n-butyltriethylammonium perchlorate.

[0033] Sodium perchlorate itself has high water solubility, providing a wider electrochemical window than typical sodium salt aqueous solutions. The presence of asymmetric alkyl perchlorate quaternary ammonium salts, with the quaternary ammonium salt itself being a large cation, reduces the relative proportion of water. The asymmetric structure endows it with stronger polarity and water-solubilizing ability, more efficiently broadening the electrochemical window. Furthermore, the irregularity of the molecule also gives it a weaker tendency to crystallize, improving the stability of the electrolyte and the corresponding battery cycle.

[0034] In some embodiments, the concentration of perchlorate ions in the electrolyte is 8-25 mol / kg, the concentration of sodium ions is 5-18 mol / kg, and the concentration of quaternary ammonium salt cations is 1-12 mol / kg.

[0035] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned aqueous sodium-ion battery electrolyte, comprising the following steps:

[0036] Sodium perchlorate and perchlorate quaternary ammonium salt are added to water and dissolved to obtain the product.

[0037] The electrolyte involved in this invention is obtained by dissolving sodium perchlorate and a quaternary ammonium perchlorate salt in a certain mass of ultrapure water. For example, 12 mol / kg sodium perchlorate + 2 mol / kg triethylmethyl perchlorate means that 12 mol of sodium perchlorate and 2 mol of triethylmethyl perchlorate are dissolved in 1 kg of water.

[0038] Based on the same inventive concept, the present invention also provides the application of the aqueous sodium-ion battery electrolyte or the aqueous sodium-ion battery electrolyte prepared by the above preparation method in the preparation of aqueous sodium-ion batteries.

[0039] Based on the same inventive concept, the present invention also provides an aqueous sodium-ion battery, including an electrolyte, wherein the electrolyte is the aqueous sodium-ion battery electrolyte described above or the aqueous sodium-ion battery electrolyte prepared by the above preparation method.

[0040] Specifically, the aqueous sodium-ion battery of the present invention includes a positive electrode, a separator, the electrolyte described above, and a negative electrode; the positive electrode includes a positive active material, preferably a Prussian blue analogue (such as Na2Mn[Fe(CN)6]); the negative electrode includes a negative active material, preferably a polyanionic compound (such as sodium titanium phosphate NaTi2(PO4)3 (NTP)).

[0041] In some embodiments, the positive electrode includes a current collector and a positive active material coated on the surface of the current collector, and the negative electrode includes a current collector and a negative active material coated on the surface of the current collector. The material of the current collector includes any one of aluminum, copper, nickel, titanium, stainless steel, carbon, etc.

[0042] In some embodiments, the preparation method of an aqueous sodium-ion battery includes:

[0043] The positive electrode active material, conductive agent (such as conductive carbon black (SuperP)), binder (such as PVDF) and N-methylpyrrolidone are mixed to obtain a mixed slurry; the slurry is coated on the corresponding current collector and dried to obtain the negative electrode sheet;

[0044] The negative electrode active material, conductive agent, binder and N-methylpyrrolidone are mixed to obtain a mixed slurry; the slurry is coated on the corresponding current collector and dried to obtain the negative electrode sheet;

[0045] Aqueous sodium-ion batteries are obtained by assembling the positive electrode, negative electrode, separator, and aqueous sodium-ion battery electrolyte.

[0046] The following further illustrates the aqueous sodium-ion battery electrolyte, its preparation method, and its application, as well as the aqueous sodium-ion battery, using specific embodiments. This section further describes the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0047] Example 1

[0048] This embodiment provides an aqueous sodium-ion battery electrolyte, comprising sodium perchlorate, perchlorate quaternary ammonium salt and water, wherein the perchlorate quaternary ammonium salt is triethylmethyl perchlorate ammonium salt;

[0049] The concentration of sodium perchlorate in the electrolyte of the aqueous sodium-ion battery is 12 mol / kg, and the concentration of triethylmethylammonium perchlorate is 2 mol / kg.

[0050] This embodiment also provides an aqueous sodium-ion battery, including a positive electrode, the electrolyte in Example 1, and a negative electrode, constituting an aqueous cup-type sodium-ion battery (similar to the structure of an electrolytic cell, with two electrodes separated by a space and inserted into an electrolyte cell, without using a separator).

[0051] The positive electrode sheet is prepared as follows: Na2Mn[Fe(CN)6], superpowder carbon black, and PVDF binder are ground evenly in a mass ratio of 70:15:15. Then, N-methylpyrrolidone organic solvent is added to form a positive electrode slurry. The positive electrode slurry is coated onto a titanium mesh and vacuum dried at 80℃ for 12 h to obtain the positive electrode sheet. The mass fraction of N-methylpyrrolidone in the positive electrode slurry is 45%.

[0052] The negative electrode sheet is prepared as follows: sodium titanium phosphate (NaTi2(PO4)3), super P carbon black, and PVDF binder are ground uniformly in a mass ratio of 70:15:15 (the mass ratio of positive electrode active material Na2Mn[Fe(CN)6] to negative electrode active material sodium titanium phosphate (NaTi2(PO4)3) is 1.2:1, and the mass ratio is adjusted by the coating amount of the positive electrode slurry and the negative electrode slurry, with the coating amount of the positive electrode slurry being greater than that of the negative electrode slurry). Then, the organic solvent N-methylpyrrolidone is added to form the negative electrode slurry. The negative electrode slurry is coated on a titanium mesh and vacuum dried at 80℃ for 12 h to obtain the negative electrode sheet. The mass fraction of N-methylpyrrolidone in the negative electrode slurry is 45%.

[0053] The positive electrode, negative electrode, and electrolyte from Example 1 are assembled to obtain an aqueous cup-type sodium-ion battery.

[0054] Example 2

[0055] This embodiment provides an aqueous sodium-ion battery electrolyte, comprising sodium perchlorate, perchlorate quaternary ammonium salt and water, wherein the perchlorate quaternary ammonium salt is triethylmethyl perchlorate ammonium salt;

[0056] The concentration of sodium perchlorate in the electrolyte of the aqueous sodium-ion battery is 12 mol / kg, and the concentration of triethylmethylammonium perchlorate is 5 mol / kg.

[0057] This embodiment also provides an aqueous sodium-ion battery, which is the same as in Embodiment 1, except that the electrolyte used is the electrolyte in Embodiment 2.

[0058] Example 3

[0059] This embodiment provides an aqueous sodium-ion battery electrolyte, comprising sodium perchlorate, perchlorate quaternary ammonium salt and water, wherein the perchlorate quaternary ammonium salt is n-propyltrimethylammonium perchlorate;

[0060] The concentration of sodium perchlorate in the electrolyte of the aqueous sodium-ion battery is 12 mol / kg, and the concentration of n-propyltrimethylammonium perchlorate is 5 mol / kg.

[0061] This embodiment also provides an aqueous sodium-ion battery, which is the same as in Embodiment 1, except that the electrolyte used is the electrolyte in Embodiment 3.

[0062] Example 4

[0063] This embodiment provides an aqueous sodium-ion battery electrolyte, comprising sodium perchlorate, perchlorate quaternary ammonium salt and water, wherein the perchlorate quaternary ammonium salt is n-propyltrimethylammonium perchlorate;

[0064] The concentration of sodium perchlorate in the electrolyte of the aqueous sodium-ion battery is 12 mol / kg, and the concentration of n-propyltrimethylammonium perchlorate is 7 mol / kg.

[0065] This embodiment also provides an aqueous sodium-ion battery, which is the same as in Embodiment 1, except that the electrolyte used is the electrolyte in Embodiment 4.

[0066] Comparative Example 1

[0067] This comparative example provides an aqueous sodium-ion battery electrolyte, comprising sodium perchlorate and water;

[0068] The sodium perchlorate concentration in the electrolyte of an aqueous sodium-ion battery is 14 mol / kg.

[0069] This comparative example also provides an aqueous sodium-ion battery, which is the same as Example 1, except that the electrolyte used is the electrolyte in Comparative Example 1.

[0070] Comparative Example 2

[0071] This embodiment provides an aqueous sodium-ion battery electrolyte, comprising sodium perchlorate, perchlorate quaternary ammonium salt and water, wherein the perchlorate quaternary ammonium salt is tetraethylammonium perchlorate;

[0072] The concentration of sodium perchlorate in the electrolyte of the aqueous sodium-ion battery is 12 mol / kg, and the concentration of tetraethylammonium perchlorate is 2 mol / kg.

[0073] This embodiment also provides an aqueous sodium-ion battery, which is the same as in Embodiment 1, except that the electrolyte used is the electrolyte in Comparative Example 2.

[0074] Performance testing

[0075] Electrochemical window testing

[0076] The electrochemical window was determined using linear sweep voltammetry, with a titanium mesh as the working electrode (i.e., using an inert current collector titanium mesh as the working electrode to determine the electrochemical window of the electrolyte itself, eliminating the possible influence of active electrode components). A foil and a saturated calomel electrode (SCE) were used as the counter and reference electrodes, respectively, with a current density reaching ±0.1 mA cm⁻¹. -2 The upper and lower limits of the decomposition potential of the electrolyte (i.e., the electrolytes in Examples 1-4 and Comparative Examples 1-2) are defined as the electrochemical window.

[0077] Aqueous sodium-ion battery charge and discharge test

[0078] The charge / discharge range is 0.5~1.5 V, and the current density is 0.1 A g. -1 Discharge capacity retention rate = discharge capacity of the current cycle / discharge capacity of the first cycle; specific capacity is calculated based on the mass of the active material of the positive electrode.

[0079] Table 1 below shows the electrochemical windows of the electrolytes in Examples 1-4 and Comparative Examples 1-2, as well as the capacity retention rate after 500 cycles after assembly into batteries.

[0080] Table 1 - Electrochemical window of electrolyte in different embodiments, and capacity retention after 500 cycles after battery assembly.

[0081] Example Electrochemical window (V) Capacity retention rate after 500 cycles (%) Example 1 2.54 62.0 Example 2 2.77 77.1 Example 3 2.92 82.5 Example 4 3.04 87.8 Comparative Example 1 2.38 34.3 Comparative Example 2 2.49 39.8

[0082] Table 1 shows that, by comparing Comparative Examples 1-2 and Example 1, it can be demonstrated that, under the condition of equal anion perchlorate concentration, using asymmetric quaternary ammonium salt cations provides a wider electrochemical window and significantly improves the cycle discharge capacity retention rate compared to using no quaternary ammonium salt cations or cations containing symmetric quaternary ammonium salts. Examples 1-4 show that further optimization of the electrolyte composition can achieve a wider electrochemical window and better cycle performance. In Example 4, using an aqueous solution of 12 mol / kg sodium perchlorate + 7 mol / kg n-propyltrimethylammonium perchlorate resulted in a wider electrochemical window and better cycle performance.

[0083] Figure 1 The electrochemical window of the electrolyte in Example 4 is shown below. Figure 1 As can be seen from the example, the electrochemical window of the electrolyte in Example 4 is 3.04 V.

[0084] Figure 2 The cycling performance curves of the aqueous sodium-ion battery assembled with the electrolyte in Example 4 are shown below. Figure 2 As can be seen from the data, the aqueous sodium-ion battery assembled with the electrolyte in Example 4 retains 87.8% of its capacity after 500 cycles.

[0085] Figure 3 The above is the charge-discharge curve of the aqueous sodium-ion battery assembled with the electrolyte in Example 4 after 500 cycles. Figure 3 As can be seen from the data, the aqueous sodium-ion battery assembled with the electrolyte in Example 4 has a discharge specific capacity (based on the mass of the positive electrode active material) of approximately 55 mAh / g, a coulombic efficiency of >98%, and still maintains a stable charge and discharge voltage plateau.

[0086] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. An aqueous sodium-ion battery electrolyte, characterized in that, The electrolyte salt comprises sodium ions and quaternary ammonium salt cations, and perchlorate anions. The quaternary ammonium salt cation is a non-symmetrical quaternary ammonium salt cation.

2. The aqueous sodium-ion battery electrolyte of claim 1, wherein, The number of carbon atoms in the quaternary ammonium salt cation is 1-8.

3. The aqueous sodium-ion battery electrolyte of claim 2, wherein, The number of carbon atoms in the quaternary ammonium salt cation is 1-4.

4. The aqueous sodium-ion battery electrolyte of claim 1, wherein, The non-symmetrical quaternary ammonium salt cation comprises at least one of triethylmethylammonium ion, n-propyltrimethylammonium ion, isopropyltrimethylammonium ion, dimethyldiethylammonium ion, methyldiethyl-n-propylammonium ion, trimethyl-n-butylammonium ion, ethyl-tripropylammonium ion, diethyl-di-n-propylammonium ion, methyl-tri-n-butylammonium ion, isopropyl-triethylammonium ion, dimethyl-ethyl-n-propylammonium ion, and n-butyl-triethylammonium ion.

5. The aqueous sodium-ion battery electrolyte of claim 1, wherein, The electrolyte salt comprises sodium perchlorate and quaternary ammonium salt perchlorate. The quaternary ammonium salt perchlorate comprises at least one of triethylmethylammonium perchlorate, n-propyltrimethylammonium perchlorate, isopropyltrimethylammonium perchlorate, dimethyldiethylammonium perchlorate, methyldiethyl-n-propylammonium perchlorate, trimethyl-n-butylammonium perchlorate, ethyl-tripropylammonium perchlorate, diethyl-di-n-propylammonium perchlorate, methyl-tri-n-butylammonium perchlorate, isopropyl-triethylammonium perchlorate, dimethyl-ethyl-n-propylammonium perchlorate, and n-butyl-triethylammonium perchlorate.

6. The aqueous sodium-ion battery electrolyte of claim 1, wherein, The concentration of the quaternary ammonium salt cation in the electrolyte is 1-12 mol / kg.

7. A method for preparing the aqueous sodium-ion battery electrolyte according to any one of claims 1-6, characterized in that, The method comprises the following steps: The sodium perchlorate and the quaternary ammonium salt perchlorate are added to water and dissolved to obtain the electrolyte.

8. Use of the aqueous sodium-ion battery electrolyte according to any one of claims 1-6 or prepared by the preparation method of claim 7 in the preparation of an aqueous sodium-ion battery.

9. An aqueous sodium-ion battery, characterized in that, The aqueous sodium-ion battery comprises the electrolyte, wherein the electrolyte is the aqueous sodium-ion battery electrolyte according to any one of claims 1-6 or prepared by the preparation method of claim 7.

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