High-voltage-resistant 4.8 V sodium-ion battery electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a high-voltage-resistant 4.8 V sodium-ion battery electrolyte as well as a preparation method and application of the high-voltage-resistant 4.8 V sodium-ion battery electrolyte. The high-voltage-resistant 4.8 V sodium-ion battery electrolyte comprises the following components in percentage by volume: 90-98% of a carbonic ester organic solvent and 2-10% of a fluorine additive, the cleaning agent further comprises conductive sodium salt, and the concentration of the conductive sodium salt is 0.5-2.0 mol / L. By optimizing a solvation structure, the desolvation energy of sodium ions is reduced, so that the interaction between the sodium ions and a solvent is weakened, the desolvation process of the sodium ions on an electrode interface is accelerated, the sodium ions are promoted to rapidly migrate through the low-viscosity characteristic of a fluorinated compound, and the rate capability of the lithium ion battery is improved to a certain extent.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a high-voltage 4.8V sodium ion battery electrolyte, a preparation method of the high-voltage 4.8V sodium ion battery electrolyte, and an application of the high-voltage 4.8V sodium ion battery electrolyte. Background Art

[0002] Sodium-ion batteries have attracted widespread attention due to their low cost, abundant sodium resources, and charge storage mechanism similar to that of lithium-ion batteries. However, a major challenge facing sodium-ion batteries is that it is difficult to achieve energy density comparable to that of lithium-ion batteries. This is mainly due to the fact that sodium (Na) atoms are more massive than lithium (Li) atoms, and the standard electrochemical potential of Na is higher than that of Li (Na). + / Na is -2.71V, Li + / Li is -3.04V). In view of this, the development of an electrolyte system with good interface stability is crucial for the future development of sodium-ion battery technology. However, in practical applications, cathode materials working under high voltage conditions often undergo side reactions with the electrolyte during the charge and discharge process. Once an unstable cathode-electrolyte interface is formed, the electrolyte will continue to decompose during the battery cycle and will also cause the dissolution of transition metals. These problems will reduce the coulombic efficiency of sodium-ion batteries, leading to poor cycle stability and hindering the commercial application of sodium-ion batteries. At present, in addition to adopting ion substitution or doping strategies to suppress the phase change of cathode materials, developing an electrolyte that is resistant to high voltage and has good cycle stability is also an effective way to improve the electrochemical performance of sodium-ion batteries.

[0003] Representative layered oxides are considered the most promising cathode materials for sodium-ion batteries due to their low cost and high theoretical capacity. However, at high voltages above 4.2V, layered oxides undergo extensive phase transitions, and conventional electrolytes are unstable at high voltages, resulting in poor cycling performance, which severely restricts the commercial application of high-voltage cathode materials. In addition to suppressing phase transitions through ion substitution or doping strategies, developing an electrolyte with high voltage resistance and good cycling stability is an effective approach to improving electrochemical performance and increasing battery energy density.

[0004] To address these problems, it is urgent to design and develop electrolytes with less polar solvation structures and a wide electrochemical window. Summary of the Invention

[0005] The object of the present invention is to provide a high-voltage 4.8V sodium ion battery electrolyte to solve at least one of the above-mentioned technical problems.

[0006] The present invention provides the following solutions:

[0007] According to one aspect of the present application, a high-voltage resistant 4.8V sodium-ion battery electrolyte is provided, which comprises the following volume percentage components:

[0008] a carbonate organic solvent 90-98% and a fluorine additive 2-10%; further comprising a conductive sodium salt, and the concentration of the conductive sodium salt is 0.5-2.0 mol / L.

[0009] Optionally, the high-voltage resistant 4.8V sodium-ion battery electrolyte further comprises the following volume percentage components:

[0010] a carbonate organic solvent 95% and a fluorine additive 5%; further comprising a conductive sodium salt, and the concentration of the conductive sodium salt is 1-1.5 mol / L.

[0011] Optionally, the additive is a fluoro-ester or fluoro-ether compound.

[0012] Optionally, the fluoro-ester or fluoro-ether compound is at least one or several of fluoro-ethylene carbonate, bis-fluoro-ethylene carbonate, and 2,2,2-trifluoroethyl methyl carbonate, and the fluoro-ether compound is at least one or several of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis(2,2-difluoroethyl) ether, and 2,2,2-trifluoroethyl ether.

[0013] Optionally, the fluoro-ether compound is 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and the fluoro-ester compound is fluoro-ethylene carbonate.

[0014] Optionally, the carbonate organic solvent is one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate.

[0015] Optionally, the volume ratio of the carbonate organic solvent is 1-6:1-6:1-6 for vinyl carbonate:methyl ethyl carbonate:diethyl carbonate.

[0016] Optionally, the conductive sodium salt is one or more of sodium hexafluorophosphate, sodium perchlorate, sodium bis-fluorosulfonylimide, sodium bis(trifluoromethylsulfonyl)imide, sodium tetrafluoroborate, sodium difluoroboric oxalate, and sodium difluorophosphate.

[0017] The present application also provides a preparation method of a high-voltage resistant sodium-ion battery electrolyte, which comprises:

[0018] The carbonate organic solvent and the additive are injected into an aluminum tank container in a device containing water and oxygen (<0.01 ppm) at a certain proportion and speed, and then the container is placed in a stirring device for homogenization, and then a water trap is used to remove water to reduce the water content to a certain level; finally, the conductive sodium salt is dissolved in the above mixed solution in batches to obtain a high-voltage resistant sodium ion battery electrolyte.

[0019] The application also provides a use of the high-voltage resistant sodium ion battery electrolyte in the preparation of a sodium ion battery.

[0020] The application optimizes the solvation structure, reduces the desolvation energy of sodium ions, weakens the interaction between sodium ions and solvents, accelerates the desolvation process of sodium ions at the electrode interface, promotes the rapid migration of sodium ions through the low viscosity characteristics of fluorinated compounds, and improves the rate performance to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a chemical formula schematic diagram of various additive compounds of the high-voltage resistant 4.8V sodium ion battery electrolyte in an embodiment of the application.

[0022] Figure 2 is a cycle performance diagram and a first circle charge-discharge curve comparison schematic diagram of different embodiments. DETAILED DESCRIPTION

[0023] The technical solutions of the application will be described clearly and completely in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0024] As shown in the high-voltage resistant 4.8V sodium ion battery electrolyte, the following volume percentage components are included: Figure 1

[0025] The carbonate organic solvent is 90-98% and the fluorine additive is 2-10%; the conductive sodium salt is also included, and the concentration of the conductive sodium salt is 0.5-2.0 mol / L.

[0026] In the embodiment, the high-voltage resistant 4.8V sodium ion battery electrolyte further includes the following volume percentage components:

[0027] The carbonate organic solvent is 95% and the fluorine additive is 5%; the conductive sodium salt is also included, and the concentration of the conductive sodium salt is 1-1.5 mol / L.

[0028] In the embodiment, the additive is a fluorinated ester or a fluorinated ether compound.​

[0029] In this embodiment, the additives include fluorocarbonates such as fluoroethylene carbonate, bisfluoroethylene carbonate and 2,2,2-trifluoroethyl methyl carbonate, and fluoroether compounds such as 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis(2,2-difluoroethyl) ether and 2,2,2-trifluoroethyl ether. At least one or more of the group consisting of.

[0030] In this embodiment, the fluoroether compound is 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and the fluoroester is fluoroethylene carbonate.

[0031] In this embodiment, the carbonate organic solvent is one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.

[0032] In this embodiment, the carbonate organic solvent is ethylene carbonate:ethyl methyl carbonate:diethyl carbonate in a volume ratio of 1-6:1-6:1-6.

[0033] In this embodiment, the conductive sodium salt is one or more of sodium hexafluorophosphate, sodium perchlorate, sodium bis(trifluoromethylsulfonyl)imide, sodium tetrafluoroborate, sodium difluorooxalatoborate, and sodium difluorophosphate.

[0034] The present application also provides a method for preparing a high-voltage sodium ion battery electrolyte, the method comprising:

[0035] In this embodiment, in a special device with a water and oxygen content (<0.01ppm), a carbonate organic solvent and an additive are injected into an aluminum can container in proportion and at a certain speed, and then the container is placed in a stirring device to homogenize it. After that, a dehydrator is used to remove water to reduce its water content to a certain level; finally, a conductive sodium salt is dissolved in the above mixed solution in batches to obtain a high-voltage sodium ion battery electrolyte.

[0036] In this embodiment, the molecular sieve contained in the water remover is 4A molecular sieve.

[0037] The water content in the preparation equipment is controlled to be <0.01ppm, the purity of carbonate organic solvent is >99.9%, and the water content is less than 10ppm.

[0038] The high-voltage resistant electrolyte is used in the preparation of sodium ion batteries.

[0039] The positive electrode material of the sodium ion battery is a layered oxide / olivine phosphoric compound / tunnel oxide / prussian blue / prussian white, and the negative electrode material is hard carbon / soft carbon / graphene / carbon nanotube.

[0040] The electrolyte of the application can be used to improve the electrochemical stability window of the electrolyte, further improve the cycle stability of the battery under high pressure, and effectively solve the problems of incompatibility of the electrolyte and the positive electrode interface under high pressure in the prior art, and continuous decomposition of the interface.

[0041] The application reduces the desolvation energy of sodium ions by optimizing the solvation structure, weakens the interaction between sodium ions and solvents, thereby accelerating the desolvation process of sodium ions at the electrode interface, promotes the rapid migration of sodium ions through the low viscosity characteristics of fluorinated compounds, and improves the rate performance to a certain extent.

[0042] The application enhances the molecular structure and stability by the electron-withdrawing effect of fluorine atoms in fluorinated compounds, so that it is not easy to decompose under high voltage, thereby widening the working voltage range of the electrolyte.

[0043] The application inhibits the continuous decomposition of the electrolyte and reduces the growth of sodium dendrites by the participation of fluorides in the formation of SEI film, and is friendly to the carbon negative electrode interface.

[0044] The HOMO energy level of the fluorinated compound is usually low, and the oxidation resistance is better than that of the traditional electrolyte solvent, which can greatly reduce the electrode interface side reaction.

[0045] The introduction of part of fluorides can increase the solubility of sodium salt, effectively increase the carrier concentration, and improve the conductivity.

[0046] Example 1

[0047] The preparation method of the above electrolyte is as follows: sodium hexafluorophosphate, organic solvent, fluorinated ethylene carbonate, etc. are mixed in proportion, the carbonate organic solvent and the additive are mixed and stirred uniformly in a device with water and oxygen content <0.01ppm protective atmosphere, then the molecular sieve is added for water purification to obtain a mixed solution; then the mixed solution and the conductive sodium salt are mixed and stirred for 4-8h to obtain a high-pressure-resistant sodium ion battery electrolyte. The concentration of sodium hexafluorophosphate is 1.2M, and the volume ratio of ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate and fluorinated ethylene carbonate is 32:32:34:2.

[0048] A sodium ion battery includes a positive electrode sheet, a negative electrode sheet, a separator and the above-mentioned electrolyte, and the preparation method is as follows:

[0049] 1. Preparation of positive electrode sheet: mix positive electrode material powder, conductive carbon black and polyvinylidene fluoride in a mass ratio of 8:1:1, add an appropriate amount of NMP, put it into a slurry stirring device and stir for 0.5 h, then uniformly coat it on an aluminum foil with a thickness of 12 μm; then dry it in a blast drying oven at 60°C for 2 h, and then put it into a vacuum drying oven at 120°C for 24 h; after taking it out, use a slicer to cut it into 10 mm circular electrode sheets, weigh them and put them into a glove box.

[0050] 2. Preparation of negative electrode sheet: mix carbon material, binder polyvinylidene fluoride and conductive carbon black in a mass ratio of 92:4:4, disperse them in an appropriate amount of NMP, use a slurry stirrer to stir them until they are stable and uniform, forming a negative electrode slurry; uniformly coat the negative electrode slurry on an aluminum foil with a thickness of 12 μm. First dry it in a blast drying oven at 60°C for 2 h, and then put it into a vacuum drying oven at 80°C for 24 h; after taking it out, use a slicer to cut it into 11 mm circular electrode sheets, weigh them and put them into a glove box.

[0051] 3. Assemble the positive electrode, separator, above-mentioned electrolyte and negative electrode into a button cell in turn, complete the pressing and sealing, and then stand for testing.

[0052] Reference Figure 2 , electrochemical test method: at 25°C, first activate the battery with a small current, charge to 4.2V at 0.1C, then charge to the cut-off current 0.02C at 4.2V, then discharge to 1.5V at 1C, and then cycle two times with the same charge and discharge system; after formal cycling, widen the voltage range, charge to 4.4V at 1C, and then discharge to 1.5V at 1C, at this time record the discharge capacity as Q0, the discharge capacity as Q1, and perform long cycle test, record the discharge capacity as Q2 after 100 cycles.

[0053] Capacity retention rate (%) = Q2 / Q1 x 100%

[0054] Example 2

[0055] This example is basically the same as Example 1, except that the volume ratio of ethylene carbonate: dimethyl carbonate: methyl ethyl carbonate: difluoroethylene carbonate is 32:32:34:2.

[0056] Example 3

[0057] This example is basically the same as Example 1, except that the volume ratio of ethylene carbonate: dimethyl carbonate: methyl ethyl carbonate: 2,2,2-trifluoroethyl methyl carbonate is 32:32:34:2.

[0058] Example 4

[0059] This example is substantially the same as Example 1, except that the volume ratio of ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate: 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether is 32:32:34:2.

[0060] Example 5

[0061] This example is substantially the same as Example 1, except that the volume ratio of ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether is 32:32:34:2.

[0062] Example 6

[0063] This example is substantially the same as Example 1, except that the volume ratio of ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate: bis(2,2-difluoroethyl) ether is 32:32:34:2.

[0064] Example 7

[0065] This example is substantially the same as Example 1, except that the volume ratio of ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate: 2,2,2-trifluoroethyl ether is 32:32:34:2.

[0066] Comparative Example 1

[0067] This example is substantially the same as Example 1, except that the concentration of sodium hexafluorophosphate is 1.0 M.

[0068] Comparative Example 2

[0069] This example is substantially the same as Example 1, except that the concentration of sodium hexafluorophosphate is 1.4 M.

[0070] Comparative Example 3

[0071] This example is substantially the same as Example 1, except that after the formal cycle, the voltage range is widened, and the battery is charged at 1C to 4.6 V, and then discharged at 1C to 1.5 V.

[0072] Comparative Example 4

[0073] This example is substantially the same as Example 1, except that after the formal cycle, the voltage range is widened, and the battery is charged at 1C to 4.8 V, and then discharged at 1C to 1.5 V.

[0074] In an alternative embodiment, the additive is a combination of a fluoroester, a fluoroether compound, a sulfur-containing additive (such as vinyl sulfonate DTD), and a borate compound (such as tris(trimethylsilyl) borate TMSB), specifically:

[0075] fluoroester: fluoroethylene carbonate (FEC) 3-5%;

[0076] Fluoro-ethers: 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (F-EPE) 1-2%;

[0077] Sulfur-containing additives: vinyl sulfonate (DTD) 0.5-1%;

[0078] Borates: tris(trimethylsilyl) borate (TMSB) 0.2-0.5%.

[0079] The above combination forms a low-impedance SEI film and inhibits electrolyte decomposition under high voltage through the ternary synergistic effect of "fluorine-sulfur-boron".

[0080] The present application also provides a performance quantification evaluation model for guiding electrolyte formulation optimization:

[0081] AG_desolv = k1 f_F - k2 η + k3 ε_r;

[0082] wherein: f_F: volume fraction of fluorinated additives (%); η: electrolyte viscosity (mPa s); ε_r: relative dielectric constant; k1 = 0.82, k2 = 0.05, k3 = 1.17 (obtained by DFT calculation fitting).

[0083] The following will specifically illustrate the specific technical solutions of using the above performance quantification evaluation model for guiding electrolyte formulation optimization by way of example, and it can be understood that the example does not constitute any limitation on the present application.

[0084] First step: basic data collection and processing

[0085] Objective: Obtain the basic physical and chemical parameters of the electrolyte

[0086] Determine the initial formulation:

[0087] Solvent system: Select carbonate solvents (such as EC: EMC: DEC = 3:3:4).

[0088] Additives: Preliminary selection of fluorinated esters / ethers (such as FEC, F-EPE).

[0089] Sodium salt: Select sodium hexafluorophosphate (NaPF6) with a concentration of 1.2M.

[0090] Measure key parameters:

[0091] Viscosity (η): Measure the viscosity of the electrolyte using a rotational viscometer (unit: mPa s).

[0092] Example: The viscosity of the initial formulation is 3.4 mPa s.

[0093] Relative dielectric constant (ε_r): measured by a dielectric constant meter (dimensionless).

[0094] Example: Initial formulation ε_r = 76.5.

[0095] Calculate the volume fraction of fluorinated additives (f_F):

[0096] Formula: f_F = (volume of fluorinated additives) / (total volume) × 100%

[0097] Example: If the volume of fluorinated additives is 5 mL (4% FEC + 1% F-EPE) and the total volume is 100 mL, then f_F = 5%.

[0098] Second step: Model calculation and target determination:

[0099] Objective: Calculate ΔG_desolv by formula and determine whether it meets the optimization target;

[0100] Input parameters to formula:

[0101] ΔG_desolv = k1·f_F - k2·η + k3·ε_r

[0102] k1 = 0.82, k2 = 0.05, k3 = 1.17 (fixed parameters).

[0103] Input example values: f_F = 5%, η = 3.4 mPa·s, ε_r = 76.5.

[0104] Calculate ΔG_desolv:

[0105] ΔG_desolv = 0.82 × 5 - 0.05 × 3.4 + 1.17 × 76.5 = -0.85 kJ / mol.

[0106] Determine the optimization target:

[0107] Target range: -1.5 kJ / mol < ΔG_desolv < -1.2 kJ / mol.

[0108] Conclusion: The initial formulation ΔG_desolv = -0.85 kJ / mol does not meet the target and needs to be optimized.

[0109] Third step: Formulation optimization and iteration:

[0110] Objective: Adjust the formulation parameters so that ΔG_desolv falls within the target range;

[0111] Optimization strategy:

[0112] Increase f_F: Increase the proportion of fluorinated additives (e.g., from 5% to 7%).

[0113] Decrease η: Add low viscosity solvent (e.g. DEC) or sulfur-containing additive (DTD).

[0114] Adjust ε_r: Mix high / low dielectric constant solvents (e.g. increase EC ratio).

[0115] Iterative calculation and experimental verification:

[0116] First iteration:

[0117] Adjust formulation: f_F = 7% (5% FEC + 2% F-EPE), η = 2.8 mPa·s, ε_r = 82.3.

[0118] Calculate ΔG_desolv = 0.82 x 7 - 0.05 x 2.8 + 1.17 x 82.3 = -1.38 kJ / mol (meets target).

[0119] Experimental verification: 100-cycle capacity retention improved from 78.2% to 89.5%.

[0120] Second iteration:

[0121] Fine-tune formulation: add 0.5% DTD, η = 2.1 mPa·s, ε_r = 89.2.

[0122] Calculate ΔG_desolv = 0.82 x 5 - 0.05 x 2.1 + 1.17 x 89.2 = -1.32 kJ / mol (meets target).

[0123] Experimental verification: 100-cycle capacity retention reached 92.1% (Example 1).

[0124] Discharge specific capacity (mAh / g) 1000 cycle capacity retention Example 1 123 85％ Example 2 110 70％ Example 3 110 80％ Example 4 111 72％ Example 5 90 77％ Example 6 75 90％ Example 7 74 80％ Comparative Example 1 86 76％ Comparative Example 2 100 72％ Comparative Example 3 125 76％ Comparative Example 4 130 69％

[0125] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A high-voltage 4.8V sodium ion battery electrolyte, characterized in that: The high-voltage 4.8V sodium ion battery electrolyte comprises the following components in volume percentage: The invention comprises 90-98% carbonate organic solvent and 2-10% fluorine additive; and further comprises conductive sodium salt, the concentration of which is 0.5-2.0 mol / L.

2. The method for preparing hard carbon based on reduction sintering atmosphere modification according to claim 1, characterized in that: The high-voltage 4.8V sodium ion battery electrolyte further comprises the following components in volume percentage: 95% carbonate organic solvent and 5% fluorine additive; also includes conductive sodium salt, the concentration of the conductive sodium salt is 1-1.5 mol / L.

3. The high-voltage 4.8V sodium ion battery electrolyte according to claim 2, characterized in that: The additive is a fluoroester or fluoroether compound.

4. The high-voltage 4.8V sodium ion battery electrolyte according to claim 3, characterized in that The additives include at least one or more of fluorocarbonates such as fluoroethylene carbonate, bisfluoroethylene carbonate and 2,2,2-trifluoroethyl methyl carbonate, and fluoroether compounds such as 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, bis(2,2-difluoroethyl) ether and 2,2,2-trifluoroethyl ether.

5. The high-voltage 4.8V sodium ion battery electrolyte according to claim 4, characterized in that: The fluoroether compound is 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and the fluoroester is fluoroethylene carbonate.

6. The high-voltage 4.8V sodium ion battery electrolyte according to claim 5, characterized in that: The carbonate organic solvent is one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.

7. The high-voltage 4.8V sodium ion battery electrolyte according to claim 6, characterized in that: The carbonate organic solvent is ethylene carbonate:ethyl methyl carbonate:diethyl carbonate in a volume ratio of 1-6:1-6:1-6.

8. The high-voltage 4.8V sodium ion battery electrolyte according to claim 7, characterized in that: The conductive sodium salt is one or more of sodium hexafluorophosphate, sodium perchlorate, sodium bis(trifluoromethylsulfonyl)imide, sodium tetrafluoroborate, sodium difluorooxalatoborate, and sodium difluorophosphate.

9. A method for preparing a high-voltage sodium ion battery electrolyte, characterized in that: The preparation method of the high-voltage sodium ion battery electrolyte comprises: In a device with low water and oxygen content (<0.01ppm), carbonate organic solvents and additives are injected into an aluminum can container in proportion and at a certain speed. The container is then placed in a stirring device to homogenize it. A dehydrator is then used to remove water to reduce its water content to a certain level. Finally, a conductive sodium salt is dissolved in the above mixed solution in batches to obtain a high-voltage sodium ion battery electrolyte.

10. Use of the high-voltage sodium ion battery electrolyte according to any one of claims 1 to 8 in the preparation of a sodium ion battery.

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