Sodium-ion battery electrolyte and sodium-ion battery
By using conjugated estrogen as an additive in sodium-ion batteries to form an inorganic-organic hybrid CEI interface film, the problems of high energy consumption aging and large gas production in sodium-ion batteries are solved, thereby improving the electrochemical performance and safety of the batteries.
Patent Information
- Application Number
- CN202510980851.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-10-17
AI Technical Summary
Sodium-ion batteries have high energy consumption, low initial coulombic efficiency, and large battery gas production during the aging process, posing safety risks. Existing additives cannot effectively solve these problems.
A novel organic anionic sodium salt with conjugated estrogen as the parent nucleus is used as an additive. Through π-π interactions, it forms a conjugated electronic environment with the cathode material, forming an inorganic-organic hybrid CEI interface film. This reduces the contact between solvent molecules and the electrode, promotes electrolyte wetting, and improves the sodium ion conduction capacity.
Shorten aging time, reduce production costs, improve battery electrochemical performance and safety, reduce battery gas production, and enhance cycle stability.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of sodium ion batteries, in particular to a sodium ion battery electrolyte and a sodium ion battery. BACKGROUND
[0002] As a potential substitute for lithium ion batteries, sodium ion batteries have attracted much attention due to their abundant sodium resources and low cost. As a core component of the battery, the electrolyte directly affects the electrochemical performance, safety and life of the battery. The electrolyte of the sodium ion battery mainly consists of sodium salt, organic solvent and additive. The main problems are as follows:
[0003] (1) The sodium ion battery usually needs to be aged after the liquid injection process, which is to promote the infiltration of the electrolyte on the surface of the electrode sheet. The aging process is generally carried out at high temperature, and the aging time is more than 36h. Therefore, the production energy consumption of the aging process is high, and the time cost is high. It increases the manufacturing cost of sodium ion batteries, which is not conducive to large-scale production.
[0004] (2) The existing electrolyte additives form a CEI film with special protective effect on the surface of the positive electrode during the first charging (formation) stage of the battery, thereby avoiding the continuous decomposition of the electrolyte. However, these additives cannot avoid the side reactions of electrolyte solvent molecules on the electrode surface, so the formed CEI film is too thick, the sodium ion conductivity is reduced, the battery resistance is increased, and a part of the active capacity of the positive electrode is irreversibly lost, ultimately resulting in low first coulomb efficiency of the battery, and reducing the reversible capacity and energy density of the sodium ion battery.
[0005] (3) The side reactions of sodium ion electrolyte solvent molecules on the electrode surface produce a series of organic by-products, hydrogen gas, short-chain alkanes, alkenes and other gases, which destroy the stability of the electrode electrolyte interface, resulting in a decrease in the reversible capacity of the battery; the generated gas will cause the battery to swell and bulge, which poses a safety hazard.
[0006] Therefore, it is urgent to improve the composition of the electrolyte of the sodium ion battery to improve the electrochemical performance of the sodium ion battery while reducing the gas production of the battery.
[0007] In view of this, the present application is proposed. SUMMARY
[0008] The purpose of the present application is to provide a sodium ion battery electrolyte and a sodium ion battery, which aims to improve the electrochemical performance of the sodium ion battery while reducing the gas production of the battery.
[0009] The present application is implemented as follows:
[0010] In a first aspect, the present application provides a sodium-ion battery electrolyte, comprising a solvent, a sodium salt and a first additive, the first additive having a structural formula of:
[0011]
[0012] wherein R1, R2, R3 and R4 are independently selected from any one of (C1-C6)alkyl, alkenyl, alkynyl, aryl, ether, ester, halide, amine, nitro, cyano, amide and sulfonic acid.
[0013] In an optional embodiment, the first additive has a mass fraction of 0.1%-5.0%, preferably 0.2%-1.0%.
[0014] In an optional embodiment, a second additive is further included, the second additive being selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, vinyl sulfate, acetonitrile and succinonitrile.
[0015] In an optional embodiment, the second additive comprises vinylene carbonate, vinyl sulfate and succinonitrile, and the mass ratio of the vinylene carbonate, the vinyl sulfate and the succinonitrile is 1:(0.5-1.5):(0.3-0.8).
[0016] In an optional embodiment, in the sodium-ion battery electrolyte, the solvent has a mass fraction of 60%-85%, the sodium salt has a mass fraction of 10%-30%, the first additive has a mass fraction of 0.1%-5.0%, and the second additive has a mass fraction of 0.1%-5.0%.
[0017] In an optional embodiment, in the sodium-ion battery electrolyte, the solvent has a mass fraction of 78%-85%, the sodium salt has a mass fraction of 10%-20%, the first additive has a mass fraction of 0.2%-1.0%, and the second additive has a mass fraction of 1.0%-4.0%.
[0018] In an optional embodiment, the solvent is selected from at least one of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, tetrahydrofuran, 1,3-dioxolane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, trimethyl phosphate and triethyl phosphate.
[0019] In an optional embodiment, the solvent is a mixed solvent formed by vinyl carbonate and diethyl carbonate, and the volume ratio of the vinyl carbonate to the diethyl carbonate is 1:(0.5-1.5).
[0020] In an optional embodiment, the sodium salt is selected from at least one of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium nitrate, sodium acetate, sodium triflate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, and sodium difluoro(oxalato)borate.
[0021] In a second aspect, the present application provides a sodium ion battery comprising the sodium ion battery electrolyte of any one of the preceding embodiments.
[0022] The present application has the following beneficial effects: the present application uses a novel organic anion sodium salt with conjugated estrogen as a mother nucleus as an additive, which can make the formed CEI interface film have high sodium ion conductivity and good toughness, is conducive to reducing the battery interface impedance, and improves the electrochemical performance of the sodium ion battery; during the formation process, due to the self-assembled adsorption layer formed by the additive molecules at the interface, solvent molecules cannot contact the electrode, so that the solvent molecules are prevented from participating in the formation of the CEI, and therefore the gas production of the battery can be reduced, and the cycle stability and safety of the sodium ion battery are improved. DETAILED DESCRIPTION
[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.
[0024] The embodiments of the present application provide a sodium ion battery electrolyte, which comprises a solvent, a sodium salt and a first additive, and the structural formula of the first additive is:
[0025]
[0026] In the formula, R1, R2, R3 and R4 are each independently selected from any one of (C1-C6)alkyl, alkenyl, alkynyl, aryl, ether, ester, halogen, amino, nitro, cyano, amide, sulfonic acid, etc., and R1, R2, R3 and R4 can be the same or different and can be any one of the above independently.
[0027] It should be noted that the embodiments of the present application use a novel organic anion sodium salt with conjugated estrogen as a mother nucleus as an additive, and the organic anion part of the additive moves to the surface of the positive electrode by electromigration, and then the conjugated part in the additive interacts with the SP 2The pi electrons on the track form a conjugated electron environment, so that the additive molecules are chemically adsorbed on the electrode surface to form a molecular adsorption layer. Therefore, during the first charging process, the adsorbed additive molecules will preferentially decompose into a film. In addition, the sulfonic acid anion group on the benzene ring has high reactivity and will decompose to form inorganic substances such as Na2S / Na2SO4 / Na2SO3. The double bond part in the parent nucleus will eventually form an inorganic-organic hybrid CEI interface film through self-polymerization. This layer interface has high sodium ion conductivity and good toughness. The following advantages are provided:
[0028] (1) This special interaction can enhance the affinity between the electrolyte and the electrode interface, promote the rapid wetting of the electrolyte on the positive and negative electrode surfaces, shorten the battery aging time, reduce the aging temperature, reduce the production cost, and improve the production efficiency.
[0029] (2) The molecular layer formed during the battery formation process preferentially participates in film formation. The sulfonic acid anion in the structure of the additive decomposes into a film during the film formation process and combines with sodium ions to form inorganic sodium salts, while the main body of the additive molecule decomposes to form organic interface components, ultimately forming an inorganic-organic hybrid CEI interface film, further improving the sodium ion conductivity of the CEI, reducing the battery interface impedance, and improving the electrochemical performance of the sodium ion battery.
[0030] (3) During the formation process, due to the self-assembled adsorption layer formed by the additive molecules on the interface, solvent molecules cannot contact the electrode, thereby avoiding the participation of solvent molecules in the formation of the CEI. Therefore, the amount of gas produced by the battery can be reduced, and the cycle stability and safety of the sodium ion battery can be improved.
[0031] In some embodiments, the mass fraction of the first additive is 0.1%-5.0%, such as 0.1%, 0.2%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, etc., and preferably 0.2%-1.0%. The mass fraction of the first additive in the electrolyte is preferably controlled within the above range to further improve the electrochemical performance of the battery while reducing the amount of gas produced.
[0032] In some embodiments, the sodium ion battery electrolyte further includes a second additive selected from at least one of vinyl carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propanesulfonic acid lactone (PS), vinyl sulfate (DTD), acetonitrile (AN), and succinonitrile (SN). The first additive provided in the embodiments of the present application can better cooperate with the above several commonly used sodium ion battery electrolyte additives, which is conducive to further improving the electrochemical performance of the sodium ion battery.
[0033] In preferred embodiments, the second additive comprises vinylene carbonate, vinyl sulfate and succindionitrile, and the mass ratio of vinylene carbonate, vinyl sulfate and succindionitrile is 1:(0.5-1.5):(0.3-0.8), such as 1:0.5:0.3, 1:0.8:0.5, 1:1.0:0.6, 1:1.2:0.7, 1:1.5:0.8, etc. By optimizing the composition of the second additive, the electrochemical performance of the sodium-ion battery is more optimal after being used in cooperation with the first additive.
[0034] In some embodiments, in the sodium-ion battery electrolyte, the mass fraction of the solvent is 60%-85%, the mass fraction of the sodium salt is 10%-30%, the mass fraction of the first additive is 0.1%-5.0%, and the mass fraction of the second additive is 0.1%-5.0%. The content of each component is more suitable within the above range, and if the amount of the additive is too large or too small, it is not conducive to the improvement of the electrochemical performance of the battery. Preferably, in the sodium-ion battery electrolyte, the mass fraction of the solvent is 78%-85%, the mass fraction of the sodium salt is 10%-20%, the mass fraction of the first additive is 0.2%-1.0%, and the mass fraction of the second additive is 1.0%-4.0%. By optimizing the amount of the solvent, the sodium salt, the first additive and the second additive, it is beneficial to further reduce the gas production and improve the cycle stability of the battery.
[0035] Specifically, the mass fraction of the solvent can be 60%, 70%, 78%, 80%, 85%, etc.; the mass fraction of the sodium salt can be 10%, 15%, 20%, 25%, 30%, etc.; the mass fraction of the first additive can be 0.1%, 0.2%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, etc.; and the mass fraction of the second additive can be 0.1%, 0.2%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, etc.
[0036] In some embodiments, the solvent is selected from at least one of vinyl carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), tetrahydrofuran (THF), 1,3-dioxolane (DOL), ethylene glycol dimethyl ether (DME), ethylene glycol diethyl ether (DEE), diethylene glycol dimethyl ether (G2), triethylene glycol dimethyl ether (G3), tetraethylene glycol dimethyl ether (G4), trimethyl phosphate (TMP) and triethyl phosphate (TEP), and the solvent of the electrolyte can be any one or several of the above.
[0037] In a preferred embodiment, the solvent is a mixed solvent formed by ethylene carbonate and diethyl carbonate, and the volume ratio of ethylene carbonate and diethyl carbonate is 1:(0.5-1.5), such as 1:0.5, 1:0.8, 1:1.0, 1:1.3, 1:1.5, etc. By optimizing the composition of the solvent, the electrolyte can be better infiltrated into the electrode sheet, and the aging time can be reduced.
[0038] In some embodiments, the sodium salt is selected from at least one of sodium hexafluorophosphate (NaPF6), sodium perchlorate (NaClO4), sodium tetrafluoroborate (NaBF4), sodium nitrate (NaNO3), sodium acetate (NaOAc), sodium triflate (NaOTf), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), and sodium difluoro(oxalato)borate (NaDFOB), and the sodium salt in the electrolyte can be any one or several of the above.
[0039] The embodiments of the present application also provide a sodium ion battery, which comprises the sodium ion battery electrolyte in any of the above embodiments, and further comprises a positive electrode sheet, a negative electrode sheet, a separator, etc., to form a complete battery structure.
[0040] The positive electrode sheet comprises a positive electrode current collector and a positive electrode active coating layer loaded on the positive electrode current collector, and the positive electrode active coating layer contains a positive electrode active material, a conductive agent (such as conductive carbon black), etc. The specific materials of the negative electrode sheet and the separator are not limited, and can be the existing negative electrode sheet and separator for sodium ion batteries.
[0041] The features and performances of the present application are further described in detail below in combination with embodiments.
[0042] Embodiment 1
[0043] The present embodiment provides a sodium ion battery electrolyte, and the preparation process is as follows:
[0044] In an argon atmosphere glove box, the moisture is controlled to be <0.1 ppm, and the oxygen value is <0.1 ppm. Ethylene carbonate (EC) and diethyl carbonate (DEC) are prepared into a mixed solvent according to a volume ratio of 1:1, and after the mixed solvent is cooled to room temperature, 14wt% of sodium hexafluorophosphate (NaPF6) based on the total mass of the electrolyte is added, and magnetic stirring is used. After the sodium hexafluorophosphate (NaPF6) is completely dissolved and cooled, 1wt% of vinylene carbonate (VC), 1wt% of vinyl sulfate (DTD), and 0.5wt% of butanedinitrile (SN) based on the total mass of the electrolyte are added, and finally 0.5wt% of conjugated estrogen (structure as follows, purchased from Shanghai Aldrin Biochemical Technology Co., Ltd., model C346113) based on the total mass of the electrolyte is added. After uniform stirring, a sodium ion battery electrolyte is obtained.
[0045]
[0046] Example 2
[0047] The present example provides a sodium-ion battery electrolyte, and the preparation process is as follows:
[0048] In the glove box under argon atmosphere, the moisture is controlled to be less than 0.1 ppm, and the oxygen value is less than 0.1 ppm. Vinyl carbonate (EC), diethyl carbonate (DEC) are prepared into a mixed solvent according to a volume ratio of 1:1.5, the mixed solvent is cooled to room temperature, then 30wt% of sodium hexafluorophosphate (NaPF6) based on the total mass of the electrolyte is added, magnetic stirring is used, and after the sodium hexafluorophosphate (NaPF6) is completely dissolved and cooled, 2wt% of vinylene carbonate (VC), 2wt% of vinyl sulfate (DTD) and 1wt% of succinonitrile (SN) based on the total mass of the electrolyte are added, finally 5wt% of conjugated estrogen (same as example 1) based on the total mass of the electrolyte is added, and the sodium-ion battery electrolyte is obtained after uniform stirring.
[0049] Example 3
[0050] The present example provides a sodium-ion battery electrolyte, and the preparation process is as follows:
[0051] In the glove box under argon atmosphere, the moisture is controlled to be less than 0.1 ppm, and the oxygen value is less than 0.1 ppm. Vinyl carbonate (EC), diethyl carbonate (DEC) are prepared into a mixed solvent according to a volume ratio of 1:1.5, the mixed solvent is cooled to room temperature, then 30wt% of sodium hexafluorophosphate (NaPF6) based on the total mass of the electrolyte is added, magnetic stirring is used, and after the sodium hexafluorophosphate (NaPF6) is completely dissolved and cooled, 2wt% of vinylene carbonate (VC), 2wt% of vinyl sulfate (DTD) and 1wt% of succinonitrile (SN) based on the total mass of the electrolyte are added, finally 5wt% of conjugated estrogen (same as example 1) based on the total mass of the electrolyte is added, and the sodium-ion battery electrolyte is obtained after uniform stirring.
[0052] Example 4
[0053] The difference from example 1 is only that the type of conjugated estrogen additive is different, and the specific structure is as follows (Shanghai Aladdin Bio-Chem Technology Co., Ltd.):
[0054]
[0055] Example 5
[0056] The difference from example 1 is only that the type of conjugated estrogen additive is different, and the specific structure is as follows (Shanghai Aladdin Bio-Chem Technology Co., Ltd.):
[0057]
[0058] Example 6
[0059] The difference from Example 1 is that the mass fraction of conjugated estrogen in the electrolyte is 0.1%.
[0060] Example 7
[0061] The difference from Example 1 is that the mass fraction of conjugated estrogen in the electrolyte is 5.0%.
[0062] Example 8
[0063] The difference from Example 1 is that the first additive is: adding 1.5wt% of vinyl sulfate (DTD) and 1wt% of succinonitrile (SN) based on the total mass of the electrolyte.
[0064] Example 9
[0065] The difference from Example 1 is that vinyl sulfate (DTD) is replaced with an equal amount of fluoroethylene carbonate (FEC).
[0066] Example 10
[0067] The difference from Example 1 is that succinonitrile (SN) is replaced with an equal amount of 1,3-propanesultone (PS).
[0068] Comparative Example 1
[0069] The preparation steps of the sodium ion battery electrolyte provided in this comparative example are as follows:
[0070] In an argon atmosphere glove box, the moisture is controlled to be <0.1 ppm, and the oxygen value is <0.1 ppm. Vinyl carbonate (EC), diethyl carbonate (DEC) are prepared into a mixed solvent according to a volume ratio of 1:1, and after the mixed solvent is cooled to room temperature, 14wt% of sodium hexafluorophosphate (NaPF6) based on the total mass of the electrolyte is added, and the mixture is stirred by magnetic force. After the sodium hexafluorophosphate (NaPF6) is completely dissolved and cooled, 1wt% of vinylene carbonate (VC), 1wt% of vinyl sulfate (DTD) and 0.5wt% of succinonitrile (SN) based on the total mass of the electrolyte are added.
[0071] The difference between Comparative Example 1 and Example 1 is that no conjugated estrogen is added.
[0072] Comparative Example 2
[0073] The difference from Example 1 is that the conjugated estrogen in Example 1 is replaced with an equal amount of tris(trimethylsilyl) phosphate (TMSP).
[0074] Test Example 1
[0075] The performance of the prepared sodium-ion battery electrolyte of the test examples and the comparative examples was tested, and the results are shown in Tables 1, 2 and 3.
[0076] Battery preparation method:
[0077] Preparation of the positive electrode: the positive electrode powder sodium iron pyrophosphate phosphate (NFPP) and conductive carbon black (SP), binder polyvinylidene fluoride (PVDF) were uniformly dispersed in N-methyl pyrrolidone (NMP) in a mass ratio of 96:1.2:2.8 to obtain a positive electrode active material slurry with a solid content of 60-65%, and then the positive electrode active material slurry was uniformly coated on both sides of the aluminum foil current collector. After vacuum oven baking, roll pressing was performed, and finally the specified size was punched to obtain the positive electrode sheet;
[0078] Preparation of the negative electrode: hard carbon and conductive carbon black (SP), binder polyvinylidene fluoride (PVDF) were uniformly dispersed in N-methyl pyrrolidone in a mass ratio of 96:1:3 to obtain a negative electrode active material slurry with a solid content of 60-65%, and then the negative electrode active material slurry was uniformly coated on both sides of the aluminum foil current collector. After vacuum oven baking, roll pressing was performed, and finally the specified size was punched to obtain the negative electrode sheet;
[0079] Battery assembly: the prepared positive electrode sheet, polyethylene separator and negative electrode sheet were stacked in order, with the separator between the positive and negative electrode sheets, and the bare cell was obtained by stacking. The bare cell was placed in an aluminum plastic film outer package to obtain a dry cell. Subsequently, the processes of liquid injection, aging, formation and aging were carried out to obtain the finished battery.
[0080] Test method: after standing at room temperature for 6h, 1C constant current charging and constant voltage charging were used, the cutoff voltage was 3.5V, and the cutoff current was 0.05C. After standing for 30min, 1C constant current discharge was carried out to 2.0V, and one charge-discharge cycle was completed.
[0081] Table 1 first cycle data of comparative examples and examples
[0082]
[0083]
[0084] As shown in Table 1, the discharge capacity of the sodium-ion battery of Example 1 using the electrolyte described in the example is significantly better than Comparative Examples 1 and 2, and the first cycle coulombic efficiency is increased to 84.30%. In addition, increasing (Examples 2, 7) or decreasing (Examples 3, 6) the content of the first additive can still increase the first discharge capacity of the battery. Examples 4 and 5 prove that introducing other functional groups to the conjugate additive mother nucleus can also improve the electrochemical performance of the sodium-ion battery. Examples 8, 9 and 10 show that changing the content and type of the second additive has little effect on the conjugate additive, and the first cycle coulombic efficiency of the battery is significantly higher than that of the comparative example.
[0085] Table 2 Comparative example and example room temperature cycle data
[0086] Group Capacity retention Cycle number Example 1 97.13％ 83 Example 2 96.56％ 65 Example 3 95.78％ 70 Example 4 95.65％ 68 Example 5 95.06％ 64 Example 6 94.67％ 77 Example 7 96.22％ 61 Example 8 95.71％ 70 Example 9 94.35％ 60 Example 10 94.96％ 73 Comparative Example 1 84.05％ 60 Comparative Example 2 83.26％ 53
[0087] As shown in Table 2, the electrolyte of Examples 1-10 exhibits a high capacity retention rate (>94%) in the long cycle test. In contrast, the reversible capacity of the electrolyte without the first additive decreases to less than 85% after cycling, with a capacity decay of more than 15%. This further proves that the additive can form a self-assembled protective layer on the electrode surface by conjugation with the electrode surface, which hinders the redox side reaction of the solvent molecules, thus effectively improving the cycle ability of the battery.
[0088] Table 3 Comparative example and example 45°C, 7-day storage gas production data
[0089] Group Gas production volume mL Example 1 11.5 Example 2 12 Example 3 12.5 Example 4 12.1 Example 5 12.3 Example 6 11.7 Example 7 13.5 Example 8 13 Example 9 14.1 Example 10 13.4 Comparative Example 1 23.7 Comparative Example 2 24.1
[0090] As shown in Table 3, due to the protective effect of the additive, the battery gas production problem is effectively inhibited, and after 7 days of high temperature (45°C) storage, the gas production of Examples 1-10 is only ~12 mL. On the contrary, due to the continuous contact reaction of the solvent molecules with the electrode surface, the gas production volume of Comparative Examples 1 and 2 is about twice that of the examples, and more than 20 mL of byproduct gas is produced.
[0091] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A sodium ion battery electrolyte, characterized in that The method comprises a solvent, a sodium salt and a first additive, wherein the structural formula of the first additive is: In the formula, R1, R2, R3 and R4 are independently selected from any one of C1-C6 alkyl, alkenyl, alkynyl, aryl, ether, ester, halide, amino, nitro, cyano, amide and sulfonic acid groups.
2. The sodium ion battery electrolyte according to claim 1, characterized in that The mass fraction of the first additive is 0.1%-5.0%, preferably 0.2%-1.0%.
3. The sodium ion battery electrolyte according to claim 1, characterized in that The invention further comprises a second additive, wherein the second additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, vinyl sulfate, acetonitrile and succinonitrile.
4. The sodium ion battery electrolyte according to claim 3, characterized in that The second additive includes vinylene carbonate, vinyl sulfate and succinonitrile, and the mass ratio of vinylene carbonate, vinyl sulfate and succinonitrile is 1:(0.5-1.5):(0.3-0.8).
5. The sodium ion battery electrolyte according to claim 3, characterized in that In the sodium ion battery electrolyte, the mass fraction of the solvent is 60%-85%, the mass fraction of the sodium salt is 10%-30%, the mass fraction of the first additive is 0.1%-5.0%, and the mass fraction of the second additive is 0.1%-5.0%.
6. The sodium ion battery electrolyte according to claim 5, characterized in that In the sodium ion battery electrolyte, the mass fraction of the solvent is 78%-85%, the mass fraction of the sodium salt is 10%-20%, the mass fraction of the first additive is 0.2%-1.0%, and the mass fraction of the second additive is 1.0%-4.0%.
7. The sodium ion battery electrolyte according to any one of claims 1 to 6, characterized in that The solvent is selected from at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, tetrahydrofuran, 1,3-dioxolane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, trimethyl phosphate and triethyl phosphate.
8. The sodium ion battery electrolyte according to claim 7, characterized in that The solvent is a mixed solvent formed by ethylene carbonate and diethyl carbonate, and the volume ratio of ethylene carbonate to diethyl carbonate is 1:(0.5-1.5).
9. The sodium ion battery electrolyte according to any one of claims 1 to 6, characterized in that The sodium salt is selected from at least one of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium nitrate, sodium acetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide and sodium difluorooxalatoborate.
10. A sodium ion battery, characterized in that: The invention comprises the sodium ion battery electrolyte according to any one of claims 1 to 9.