High-voltage ether electrolyte and application thereof in sodium-ion battery

Abstract

The invention relates to the technical field of battery energy storage, in particular to a high-voltage ether electrolyte and application thereof in a sodium-ion battery. The high-voltage ether electrolyte has excellent electrochemical performance in a high-temperature environment and is high in high-temperature adaptability; the electrochemical window of the material can reach 4.8 V, and the material has excellent oxidation resistance; the sodium ion battery assembled by using the high-voltage ether electrolyte provided by the invention circulates for 100 circles under the conditions of 2.0-4.4 V and 1 C, the capacity retention ratio is 70% or above, and the sodium ion battery has excellent high-voltage stability. The sodium ion battery containing the high-voltage ether electrolyte has excellent high-temperature cycling stability and room-temperature cycling stability, and high capacity retention ratio. In addition, the high-voltage ether electrolyte is simple in preparation process, low in raw material cost and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of battery energy storage technology, and in particular to a high-voltage ether electrolyte and its application in sodium-ion batteries. Background Technology

[0002] Sodium-ion batteries, with their abundant and inexpensive sodium resources and similar electrochemical properties to lithium, show great promise for large-scale energy storage. With the rapid development of the new energy industry, higher demands are being placed on the energy density of sodium-ion batteries. Increasing the operating voltage is one of the key paths to overcoming the energy density bottleneck in sodium-ion battery systems.

[0003] In recent years, ether solvents have shown significant advantages in sodium-ion battery systems due to their low viscosity, high sodium salt solubility, excellent temperature adaptability, and good electrode compatibility. However, the lone pair electrons of the oxygen atom in the ether bond (COC) of ether solvent molecules have an electron-donating effect, and the α-H atoms are active. Under high voltage conditions (> 4.0 V vs. Na), the performance of these solvents may be affected. + / Na) is easily oxidized and decomposed; this defect causes the electrochemical performance of ether solvent electrolytes to deteriorate continuously, which in turn leads to rapid capacity decay and reduced cycle life, severely limiting the application of ether solvents in high-voltage sodium-ion batteries.

[0004] Therefore, developing a novel ether electrolyte system with excellent high voltage stability is of great significance for promoting the application of high-voltage sodium-ion batteries in the field of large-scale energy storage. Summary of the Invention

[0005] This invention provides a high-voltage ether electrolyte, which features strong high-temperature adaptability, a wide electrochemical window, and excellent high-voltage stability. Sodium-ion batteries containing this high-voltage ether electrolyte exhibit excellent high-temperature cycling stability and room-temperature cycling stability, as well as high capacity retention. Furthermore, the preparation process of this high-voltage ether electrolyte is simple, the raw material cost is low, and it is suitable for large-scale production.

[0006] The present invention also provides a sodium-ion battery comprising the above-mentioned high-voltage ether electrolyte. This sodium-ion battery has excellent high-temperature cycle stability and room-temperature cycle stability, as well as high capacity retention, providing new ideas and strategies for the preparation of high-voltage sodium-ion batteries and has good prospects for industrial application.

[0007] A first aspect of the present invention provides a high-voltage ether electrolyte comprising a sodium salt solution and a dual-ligand organic framework material additive; wherein the sodium salt solution is composed of a sodium salt and an ether solvent, and the dual-ligand organic framework material additive is prepared by a Schiff base reaction of an aldehyde ligand and an amino ligand; wherein the dual-ligand organic framework material additive has an irregular blocky particle morphology.

[0008] The aldehyde ligand is one of R1-1, R1-2, R1-3, R1-4, R1-5, R1-6, R1-7, and R1-8:

[0009] ;

[0010] The amino ligand is one of R2-1, R2-2, R2-3, and R2-4:

[0011] .

[0012] The high-voltage ether electrolyte described above, wherein the dual-ligand organic framework material additive is obtained by a preparation method comprising the following steps:

[0013] A reaction system was prepared using aldehyde and amino ligands as raw materials and trifluoroacetic acid as a catalyst.

[0014] The reaction system was continuously stirred at room temperature, and crystals precipitated. The crystals were collected to obtain the dual-ligand organic framework material additive.

[0015] In the high-voltage ether electrolyte described above, the molar ratio of aldehyde ligand to amino ligand in the reaction system is 1:(1-2).

[0016] The high-voltage ether electrolyte described above, wherein the reaction system is prepared using aldehyde and amino ligands as raw materials and trifluoroacetic acid as a catalyst, specifically includes:

[0017] S1. Dissolve the aldehyde ligand in anhydrous dichloromethane to obtain solution A;

[0018] S2. Dissolve the amino ligand in anhydrous methanol to obtain solution B;

[0019] S3. Under room temperature and magnetic stirring, solution B is added dropwise to solution A to obtain a light yellow mixed solution;

[0020] S4. Add trifluoroacetic acid catalyst to the mixed solution to obtain the reaction system.

[0021] In the high-voltage ether electrolyte described above, in step S1, the concentration of the aldehyde ligand in solution A is 0.05-0.1 mol / L;

[0022] And / or, in solution B, the concentration of the amino ligand is 0.05-0.2 mol / L.

[0023] In the high-voltage ether electrolyte described above, the concentration of the dual-ligand organic framework material additive is 1-10 mg / mL.

[0024] In the high-voltage ether electrolyte described above, the concentration of the sodium salt in the sodium salt solution is 0.5-3 mol / L.

[0025] In the high-voltage ether electrolyte described above, the sodium salt is at least one of sodium hexafluorophosphate, sodium perchlorate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium bis(oxalato)borate, and sodium difluorooxalato)borate.

[0026] The high-voltage ether electrolyte described above, wherein the ether solvent is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, 1,4-dioxane, and fluoroethers.

[0027] A second aspect of the present invention provides a sodium-ion battery comprising the aforementioned high-voltage ether electrolyte.

[0028] The solution of the present invention has at least the following effects:

[0029] (1) The high-voltage ether electrolyte provided by the present invention has excellent electrochemical performance in high temperature (e.g., 60°C) environment and strong high temperature adaptability; its electrochemical window can reach 4.8V and has excellent anti-oxidation ability; the sodium-ion battery assembled using the high-voltage ether electrolyte provided by the present invention can retain more than 70% of its capacity after 100 cycles at 25°C or 60°C, 2.0-4.4V, and 1C, and has excellent high voltage stability.

[0030] (2) Compared with traditional ether electrolytes, the present invention introduces dual-ligand organic framework material additives, which enables the high-voltage ether electrolyte to attract and anchor ether solvent molecules. Through the anchoring effect on ether solvents, the antioxidant capacity of the electrolyte is significantly improved.

[0031] (3) Compared with sodium-ion batteries containing traditional ether electrolytes, sodium-ion batteries containing the high-voltage ether electrolyte of the present invention have better high-temperature cycling stability and room-temperature cycling stability, as well as higher capacity retention, providing new ideas and strategies for the preparation of high-voltage sodium-ion batteries and having good industrial application prospects. Attached Figure Description

[0032] 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.

[0033] Figure 1 XPS image of the dual-ligand organic framework material additive in Example 1 of this invention;

[0034] Figure 2 The infrared spectrum of the dual-ligand organic framework material additive in Example 1 of this invention;

[0035] Figure 3 This is a SEM image of the dual-ligand organic framework material additive in Example 1 of the present invention;

[0036] Figure 4 The electrochemical window test results are for the high-voltage ether electrolyte in Example 1 and the ether electrolyte in Comparative Example 1 of this invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this art or in accordance with the product instructions. Reagents or instruments used without specified manufacturers are all conventional products that can be obtained commercially.

[0038] It should be noted that in this invention, "and / or" means at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0039] In this invention, the use of terms such as "first" and "second" is for distinguishing similar objects and not for describing a specific order or sequence, and therefore should not be construed as a limitation of this invention.

[0040] In the following description, the terms “including,” “containing,” “having,” and “containing” are open-ended terms, meaning that they include but are not limited to.

[0041] Those skilled in the art should understand that, in the following description of the embodiments of the present invention, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0042] Those skilled in the art will understand that the numerical ranges in the embodiments of the present invention should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, the technical / scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] A first aspect of the present invention provides a high-voltage ether electrolyte comprising a sodium salt solution and a dual-ligand organic framework material additive; wherein the sodium salt solution is composed of a sodium salt and an ether solvent, and the dual-ligand organic framework material additive is prepared by a Schiff base reaction of an aldehyde ligand and an amino ligand; wherein the dual-ligand organic framework material additive has an irregular blocky particle morphology.

[0045] The aldehyde ligand is one of R1-1, R1-2, R1-3, R1-4, R1-5, R1-6, R1-7, and R1-8:

[0046] ;

[0047] The amino ligand is one of R2-1, R2-2, R2-3, and R2-4:

[0048] .

[0049] In this invention, the Chinese name of R1-1 is: [1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde; the Chinese name of R1-2 is: 5,5'-(benzoquinoline-4,7-diyl)di-m-phenylenedialdehyde; the Chinese name of R1-3 is: 5,5'-(benzoisoquinoline-4,7-diyl)di-m-phenylenedialdehyde; and the Chinese name of R1-4 is: 5,5'-(benzopyran-4,7-diyl) The Chinese names for R1-5 are: 5,5'-(benzothiophene-4,7-diyl)di-m-phenylenedialdehyde; the Chinese names for R1-6 are: 5,5'-(benzothiadiazole-4,7-diyl)di-m-phenylenedialdehyde; the Chinese names for R1-7 are: 5,5'-(benzotriazole-4,7-diyl)di-m-phenylenedialdehyde; and the Chinese names for R1-8 are: 5,5'-(benzothiadiazole-4,7-diyl)di-m-phenylenedialdehyde.

[0050] In this invention, the Chinese name of R2-1 is ethylenediamine; the Chinese name of R2-2 is levorotatory-trans-1,2-cyclohexanediamine; the Chinese name of R2-3 is o-phenylenediamine; and the Chinese name of R2-4 is 1,1'-biphenyl-3,3'-diamine.

[0051] In this invention, the aldehyde ligand is preferably one of R1-7 and R1-8; the amino ligand is preferably one of R2-2 and R2-3.

[0052] The present invention does not impose any particular limitation on the specific source or preparation method of the above-mentioned aldehyde ligands and amino ligands. They can be obtained through conventional means or prepared according to methods known in the art.

[0053] The high-voltage ether electrolyte provided by this invention exhibits excellent electrochemical performance at high temperatures (e.g., 60°C) and strong high-temperature adaptability; its electrochemical window can reach 4.8V, and it has excellent oxidation resistance; sodium-ion batteries assembled using the high-voltage ether electrolyte provided by this invention retain more than 70% of their capacity after 100 cycles at 2.0-4.4V and 1C, demonstrating excellent high-voltage stability.

[0054] The high-voltage ether electrolyte provided by this invention has the characteristics of a wide electrochemical window and excellent high-voltage stability. The inventors believe that the reason may be that the introduced dual-ligand organic framework material additive has a cavity structure, which can attract and anchor ether solvent molecules. This gives the prepared high-voltage ether electrolyte the ability to attract and anchor ether solvent molecules. Through the anchoring effect on ether solvents, the antioxidant capacity of the electrolyte is significantly improved, and the prepared high-voltage ether electrolyte has a wide electrochemical window and excellent high-voltage stability.

[0055] In some embodiments, the dual-ligand organic framework material additive is obtained by a preparation method comprising the following steps:

[0056] A reaction system was prepared using aldehyde and amino ligands as raw materials and trifluoroacetic acid as a catalyst.

[0057] The reaction system was continuously stirred at room temperature, and crystals precipitated. The crystals were collected to obtain the dual-ligand organic framework material additive.

[0058] The principle of preparing the dual-ligand organic framework material additive of this invention is explained as follows: The electron-rich nitrogen atom in the amino group nucleophilically attacks the partially positively charged carbon atom on the aldehyde group, forming an unstable hydroxyl halfamine intermediate. This intermediate then undergoes intramolecular proton transfer and eliminates a water molecule, ultimately forming a strong carbon-nitrogen double bond, i.e., an imine bond (Schiff base), between the two ligands. The key role of this condensation reaction is that it acts like a molecular-level "needle and thread," precisely and directionally "stitching" the pre-designed bifunctional ligand units (i.e., aldehyde and amino ligands) together through covalent bonds (C=N bonds) to form a dual-ligand organic framework material with a dynamic covalent cross-linking network. Furthermore, in Example 1 of this invention, the presence of the NSN structure in the dual-ligand organic framework material additive not only enhances the rigidity of the entire framework but may also regulate the electron distribution of the dual-ligand organic framework material through the electronic effect of sulfur, thereby synergistically improving its stability and interfacial interaction capabilities as an additive in the target application system.

[0059] In some embodiments, the molar ratio of the aldehyde ligand to the amino ligand in the reaction system is 1:(1-2).

[0060] When the molar ratio of aldehyde ligand to amino ligand is within the above range, dual-ligand organic framework material additives can be successfully prepared.

[0061] In some embodiments, the preparation of the reaction system using aldehyde and amino ligands as raw materials and trifluoroacetic acid as a catalyst specifically includes:

[0062] S1. Dissolve the aldehyde ligand in anhydrous dichloromethane to obtain solution A;

[0063] S2. Dissolve the amino ligand in anhydrous methanol to obtain solution B;

[0064] S3. Under room temperature and magnetic stirring, solution B is added dropwise to solution A to obtain a light yellow mixed solution;

[0065] S4. Add trifluoroacetic acid catalyst to the mixed solution to obtain the reaction system.

[0066] In some embodiments, in step S1, the concentration of the aldehyde ligand in solution A is 0.05-0.1 mol / L.

[0067] In some embodiments, in step S2, the concentration of the amino ligand in solution B is 0.05-0.2 mol / L.

[0068] In this invention, after collecting the crystals, the process further includes washing and drying the collected crystals. The washing process is to remove unreacted amino ligands, aldehyde ligands, and byproducts; the drying process is to remove residual solvents (such as methanol and dichloromethane) and other volatile impurities from the material, in order to obtain a structurally stable dual-ligand organic framework material additive.

[0069] In some embodiments, the concentration of the dual-ligand organic framework material additive in the high-voltage ether electrolyte is 1-10 mg / mL, preferably 2-5 mg / mL.

[0070] In some embodiments, the concentration of the sodium salt in the sodium salt solution is 0.5-3 mol / L, preferably 1-1.5 mol / L.

[0071] In the high-voltage ether electrolyte described above, the sodium salt is at least one of sodium hexafluorophosphate, sodium perchlorate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium bis(oxalateborate), and sodium difluorooxalateborate, preferably at least one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

[0072] In some embodiments, the ether solvent is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, 1,4-dioxane, and fluoroethers, preferably at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

[0073] A second aspect of the present invention provides a sodium-ion battery comprising the aforementioned high-voltage ether electrolyte.

[0074] The present invention will be further described below through specific embodiments.

[0075] In the following examples, NaNi 0.33 Fe 0.33 Mn 0.33 O2 was purchased from KELOULD.

[0076] Example 1

[0077] The high-voltage ether electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0078] (1) Preparation of additives for dual-ligand organic framework materials:

[0079] S1. Dissolve 0.62 mmol of the aldehyde ligand in 10 mL of anhydrous dichloromethane to obtain solution A; the structural formula of the aldehyde ligand is as follows:

[0080] ;

[0081] S2. Dissolve 0.62 mmol of the amino ligand in 10 mL of anhydrous methanol to obtain solution B; the structural formula of the amino ligand is as follows:

[0082] ;

[0083] S3. Under room temperature and magnetic stirring, solution B is added dropwise to solution A to obtain a light yellow mixed solution;

[0084] S4. Add 0.1 ml of trifluoroacetic acid catalyst to the mixed solution to obtain the reaction system;

[0085] S5. The reaction system is continuously stirred at room temperature until crystals precipitate out; collect the crystals.

[0086] S6. The collected crystals are washed alternately with methanol and dichloromethane to remove unreacted amino ligands, aldehyde ligands and byproducts. The washed crystals are then transferred to a vacuum drying oven for drying to obtain a dual-ligand organic framework material additive.

[0087] (2) In a glove box, sodium hexafluorophosphate (NaPF6) is added to ethylene glycol dimethyl ether solvent to prepare a sodium salt solution; the concentration of NaPF6 in the sodium salt solution is 1 mol / L.

[0088] (3) Add the dual-ligand organic framework material additive to the sodium salt solution to make the final concentration of the dual-ligand organic framework material additive 2 mg / mL, stir at room temperature for 12 h, mix evenly, and obtain a high-voltage ether electrolyte.

[0089] Example 2 (Sodium salt is NaTFSI)

[0090] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0091] (2) In a glove box, sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) is added to ethylene glycol dimethyl ether solvent to prepare a sodium salt solution; the concentration of NaTFSI in the sodium salt solution is 1.5 mol / L.

[0092] Example 3 (Sodium salt is NaFSI)

[0093] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0094] (2) In a glove box, sodium bis(fluorosulfonyl)imide (NaFSI) is added to ethylene glycol dimethyl ether solvent to prepare a sodium salt solution; the concentration of NaFSI in the sodium salt solution is 1.5 mol / L.

[0095] Example 4

[0096] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0097] In step (1), specifically in step S1, the structural formula of the aldehyde ligand is as follows:

[0098] ;

[0099] In step S2, the structural formula of the amino ligand is as follows:

[0100] .

[0101] Example 5

[0102] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0103] In step (2), the concentration of NaPF6 in the sodium salt solution is 1.5 mol / L.

[0104] Example 6

[0105] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0106] In step (3), the final concentration of the dual-ligand organic framework material additive is 3 mg / mL.

[0107] Example 7

[0108] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0109] In step (3), the final concentration of the dual-ligand organic framework material additive is 5 mg / mL.

[0110] Example 8

[0111] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 1, except that:

[0112] In step (2), the ethylene glycol dimethyl ether solvent is replaced with a mixed solvent (obtained by mixing ethylene glycol dimethyl ether solvent and tetraethylene glycol dimethyl ether solvent in a volume ratio of 3:7).

[0113] Example 9

[0114] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 2, except that:

[0115] In step (3), the final concentration of the dual-ligand organic framework material additive is 3 mg / mL.

[0116] Example 10

[0117] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 2, except that:

[0118] In step (3), the final concentration of the dual-ligand organic framework material additive is 5 mg / mL.

[0119] Example 11

[0120] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 2, except that:

[0121] In step (2), the ethylene glycol dimethyl ether solvent is replaced with a mixed solvent (obtained by mixing ethylene glycol dimethyl ether solvent and tetraethylene glycol dimethyl ether solvent in a volume ratio of 3:7).

[0122] Example 12

[0123] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 3, except that:

[0124] In step (3), the final concentration of the dual-ligand organic framework material additive is 5 mg / mL.

[0125] Example 13

[0126] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 4, except that:

[0127] (2) In a glove box, sodium bis(fluorosulfonyl)imide (NaFSI) is added to ethylene glycol dimethyl ether solvent to prepare a sodium salt solution; the concentration of NaFSI in the sodium salt solution is 1.5 mol / L.

[0128] Example 14

[0129] The high-voltage ether electrolyte provided in this embodiment is basically the same as that in Example 4, except that:

[0130] In step (3), the final concentration of the dual-ligand organic framework material additive is 5 mg / mL.

[0131] Comparative Example 1

[0132] The ether electrolyte provided in this comparative example is obtained by a preparation method including the following process:

[0133] Sodium hexafluorophosphate (NaPF6) was added to ethylene glycol dimethyl ether solvent in a glove box and stirred at room temperature for 12 hours to obtain a homogeneous ether electrolyte; the concentration of NaPF6 in the ether electrolyte was 1 mol / L.

[0134] Comparative Example 2

[0135] The ether electrolyte provided in this comparative example is obtained by a preparation method including the following process:

[0136] In a glove box, sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) was added to ethylene glycol dimethyl ether solvent and stirred at room temperature for 12 hours until homogeneous to prepare an ether electrolyte; the concentration of NaTFSI in the ether electrolyte was 1.5 mol / L.

[0137] Comparative Example 3

[0138] The ether electrolyte provided in this comparative example is obtained by a preparation method including the following process:

[0139] In a glove box, sodium bis(fluorosulfonyl)imide (NaFSI) was added to ethylene glycol dimethyl ether solvent and stirred at room temperature for 12 hours to obtain a homogeneous ether electrolyte; the concentration of NaFSI in the ether electrolyte was 1.5 mol / L.

[0140] Comparative Example 4

[0141] The ether electrolyte provided in this comparative example is basically the same as that in Comparative Example 1, except that:

[0142] Replace the ethylene glycol dimethyl ether solvent with a mixed solvent (obtained by mixing ethylene glycol dimethyl ether solvent and tetraethylene glycol dimethyl ether solvent in a volume ratio of 3:7).

[0143] Comparative Example 5

[0144] The ether electrolyte provided in this comparative example is basically the same as that in Comparative Example 1, except that:

[0145] The concentration of NaPF6 in the ether electrolyte is 1.5 mol / L.

[0146] Comparative Example 6

[0147] The ether electrolyte provided in this comparative example is basically the same as that in comparative example 2, except that:

[0148] Replace the ethylene glycol dimethyl ether solvent with a mixed solvent (obtained by mixing ethylene glycol dimethyl ether solvent and tetraethylene glycol dimethyl ether solvent in a volume ratio of 3:7).

[0149] Comparative Example 7

[0150] The ether electrolyte provided in this comparative example is basically the same as that in comparative example 3, except that:

[0151] Replace the ethylene glycol dimethyl ether solvent with a mixed solvent (obtained by mixing ethylene glycol dimethyl ether solvent and tetraethylene glycol dimethyl ether solvent in a volume ratio of 3:7).

[0152] Performance testing

[0153] 1. X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy were performed on the dual-ligand organic framework material additive in Example 1 of this invention, respectively. Figure 1 and Figure 2 As shown; Figure 1 XPS image of the dual-ligand organic framework material additive in Example 1 of this invention; Figure 2 The image shows the infrared spectrum of the dual-ligand organic framework material additive in Example 1 of this invention.

[0154] Depend on Figure 1 It can be seen that the dual-ligand organic framework material additive in Example 1 contains S, C, N and O elements, combined with the characterization results of infrared spectroscopy ( Figure 2 ): at 1720 cm -1 The strong absorption peaks nearby are attributed to the stretching vibrations of the C=O bonds in the aldehyde group, at 3400 cm⁻¹. -1 The broad absorption peak near 1450 cm⁻¹ indicates the presence of an amino group (-NH₂). -1 The absorption peak at 650 cm⁻¹ corresponds to the skeletal vibration of the aromatic ring. -1 The nearby absorption peak is attributed to the vibration of the NSN bond, at 1642 cm⁻¹. -1 The absorption peak at the specified location indicates the presence of C=N bonds, demonstrating that a Schiff base reaction successfully occurred between the aldehyde ligand and the amino ligand, forming a dynamically covalently cross-linked imine structure. These results confirm that this dual-ligand organic framework material additive simultaneously contains aldehyde functional groups, aromatic ring structures, amino functional groups, and an NSN-characteristic structure, successfully achieving a synergistic complexation of aldehyde and amino ligands.

[0155] 2. The dual-ligand organic framework material additive in Example 1 of this invention was tested using scanning electron microscopy (SEM), such as... Figure 3 As shown; Figure 3 This is a SEM image of the dual-ligand organic framework material additive in Example 1 of the present invention.

[0156] Depend on Figure 3 It can be seen that the morphology of the dual-ligand organic framework material additive is irregular blocky particles.

[0157] 3. Electrochemical window tests were performed on the high-voltage ether electrolyte in Example 1 and the ether electrolyte in Comparative Example 1, respectively. Figure 4 As shown; Figure 4 The electrochemical window test results are for the high-voltage ether electrolyte in Example 1 and the ether electrolyte in Comparative Example 1 of this invention.

[0158] Depend on Figure 4 It can be seen that the electrochemical window of the ether electrolyte in Comparative Example 1 is the highest at 4.2 V, while the electrochemical window of the high-voltage ether electrolyte in Example 1 of the present invention is as high as 4.8 V. Compared with Comparative Example 1, the electrochemical window of the high-voltage ether electrolyte in Example 1 is significantly improved, indicating that the high-voltage ether electrolyte provided by the present invention has excellent antioxidant capacity.

[0159] 4. To clarify the electrochemical performance of the high-voltage ether electrolyte provided in the embodiments of the present invention, the high-voltage ether electrolytes in Examples 1-14 of the present invention and the ether electrolytes in Comparative Examples 1-7 were used as electrolyte samples for the assembly of sodium-ion batteries: the positive electrode material NaNi 0.33 Fe 0.33 Mn 0.33 O2, conductive agent Super P, and binder PVDF are mixed in a mass ratio of 8:1:1 to form the working electrode. A sodium sheet is used as the counter electrode. The electrolyte sample is then assembled together to form a coin cell sodium-ion battery.

[0160] Test conditions: Constant current charge and discharge at room temperature (25℃) or high temperature (60℃) with a voltage range of 2.0-4.4V; the assembled coin sodium-ion battery was first pre-cycled 3 times at a current density of 0.1 C, and then cyclic charge and discharge was performed at a current density of 1 C. The test results are shown in Table 1 and Table 2.

[0161] Table 1. Electrochemical performance test results of Examples 1-15

[0162]

[0163] Table 1. Electrochemical performance test results of Comparative Examples 1-7

[0164]

[0165] As shown in Tables 1 and 2, the sodium-ion batteries assembled using the high-voltage ether electrolyte provided in the embodiments of the present invention exhibit higher high-temperature cycle stability, room-temperature cycle stability, and capacity retention than Comparative Examples 1-7. Compared to Comparative Example 1, under conditions of 25°C or 60°C, a current density of 1C, and a voltage window of 2.0-4.4V, the sodium-ion batteries assembled using the high-voltage ether electrolyte in the embodiments demonstrate superior high-temperature cycle stability, room-temperature cycle stability, and higher capacity retention.

[0166] In summary, the high-voltage ether electrolyte provided in this embodiment of the invention exhibits excellent electrochemical performance and strong high-temperature adaptability under high-temperature conditions (e.g., 60°C); its electrochemical window can reach 4.8V, and it has excellent oxidation resistance; the sodium-ion battery assembled using the high-voltage ether electrolyte provided in this invention retains more than 70% of its capacity after 100 cycles at 25°C or 60°C, 2.0-4.4V, and 1C, demonstrating excellent high-voltage stability.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-voltage ether electrolyte, characterized in that, The invention comprises a sodium salt solution and a dual-ligand organic framework material additive; the sodium salt solution is composed of a sodium salt and an ether solvent, and the dual-ligand organic framework material additive is prepared by a Schiff base reaction of an aldehyde ligand and an amino ligand; the dual-ligand organic framework material additive has an irregular blocky particle morphology. The aldehyde ligand is one of R1-1, R1-2, R1-3, R1-4, R1-5, R1-6, R1-7, and R1-8: ； The amino ligand is one of R2-1, R2-2, R2-3, and R2-4: 。 2. The high-voltage ether electrolyte according to claim 1, characterized in that, The dual-ligand organic framework material additive is obtained by a preparation method comprising the following steps: A reaction system was prepared using aldehyde and amino ligands as raw materials and trifluoroacetic acid as a catalyst. The reaction system was continuously stirred at room temperature, and crystals precipitated. The crystals were collected to obtain the dual-ligand organic framework material additive.

3. The high-voltage ether electrolyte according to claim 2, characterized in that, In the reaction system, the molar ratio of aldehyde ligand to amino ligand is 1:(1-2).

4. The high-voltage ether electrolyte according to claim 2, characterized in that, The reaction system prepared using aldehyde and amino ligands as raw materials and trifluoroacetic acid as a catalyst specifically includes: S1. Dissolve the aldehyde ligand in anhydrous dichloromethane to obtain solution A; S2. Dissolve the amino ligand in anhydrous methanol to obtain solution B; S3. Under room temperature and magnetic stirring, solution B is added dropwise to solution A to obtain a light yellow mixed solution; S4. Add trifluoroacetic acid catalyst to the mixed solution to obtain the reaction system.

5. The high-voltage ether electrolyte according to claim 1, characterized in that, In step S1, the concentration of the aldehyde ligand in solution A is 0.05-0.1 mol / L; And / or, in step S2, the concentration of the amino ligand in solution B is 0.05-0.2 mol / L.

6. The high-voltage ether electrolyte according to claim 1, characterized in that, In the high-voltage ether electrolyte, the concentration of the dual-ligand organic framework material additive is 1-10 mg / mL.

7. The high-voltage ether electrolyte according to claim 1, characterized in that, The sodium salt concentration in the sodium salt solution is 0.5-3 mol / L.

8. The high-voltage ether electrolyte according to claim 1, characterized in that, The sodium salt is at least one of sodium hexafluorophosphate, sodium perchlorate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium bis(oxalateborate), and sodium difluorooxalateborate.

9. The high-voltage ether electrolyte according to claim 1, characterized in that, The ether solvent is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, 1,4-dioxane, and fluoroethers.

10. A sodium-ion battery, characterized in that, Includes the high-voltage ether electrolyte as described in any one of claims 1-9.

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