Electrolyte, battery, battery pack and electric equipment

Abstract

The invention relates to the technical field of electrolyte, in particular to electrolyte, a battery, a battery pack and electric equipment. The electrolyte comprises an additive, the additive comprises a first film-forming agent, and the first film-forming agent comprises erythritol disulfate and a compound as shown in the following formula (1), wherein R1 to R3 are independently selected from at least one of H and substituted or unsubstituted C1-C30 alkyl groups, and R4 to R6 are independently selected from at least one of H and F and have at least one F. The electrolyte is beneficial to formation of a more stable SEI film, thereby being beneficial to improvement of the cycle performance of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrolyte, a battery, a battery pack and an electrical equipment. BACKGROUND

[0002] As a bridge connecting the positive and negative electrodes, the physical and chemical properties and composition of the electrolyte are directly related to the comprehensive performance of the battery. The electrolyte plays an important role in the formation of the solid electrolyte interface film (SEI film) in the battery, and the stability of the SEI film is of great significance to the cycle performance and safety performance of the battery.

[0003] However, during the operation of the battery, the electrolyte will decompose to produce oxides and reduction products, which will chemically react with the SEI film, causing the structure of the film to be destroyed, and thus affecting the cycle performance and safety performance of the battery. Therefore, developing an electrolyte that can improve the stability of the film is of great significance to improving the cycle performance and safety performance of the battery. SUMMARY

[0004] The electrolyte provided by the present application is conducive to the formation of a more stable SEI film, thereby improving the cycle performance and safety performance of the battery.

[0005] The battery provided by the present application has excellent cycle performance.

[0006] The electrical equipment provided by the present application has a long service life.

[0007] The electrolyte provided by the present application includes an additive, and the additive includes a first film-forming agent, and the first film-forming agent includes erythritol disulfate and a compound represented by the following formula (1):

[0008] Formula (1);

[0009] wherein R1-R3 are independently selected from at least one of H, a substituted or unsubstituted C1-C30 alkyl group, R4-R6 are independently selected from at least one of H, F, and at least one F is present in R4-R6.

[0010] In the electrolyte described above, R1-R3 are independently selected from at least one of a substituted or unsubstituted C1-C4 alkyl group.

[0011] In the electrolyte described above, R4-R6 are both F.

[0012] In the electrolyte described above, the mass fraction of the compound represented by formula (1) in the electrolyte is 0.5-5%.

[0013] The electrolyte, the mass percentage of the erythritol disulfate in the electrolyte is 0.1-5%.

[0014] The electrolyte, the additive further comprises one or more of a second film-forming agent, a flame retardant, a water-removing agent, and an overcharge protection agent.

[0015] The electrolyte, the second film-forming agent comprises at least one of fluoroethylene carbonate, vinylene carbonate, 1,3-propane sulfolactone, propylene sulfite, propenyl-1,3-sulfonic acid lactone, and methylene methane disulfonate; and / or the flame retardant comprises at least one of trimethyl phosphate, ethoxy (pentafluoro) cyclo-triphosphazene; and / or the water-removing agent comprises at least one of butanedinitrile and hexanedinitrile; and / or the overcharge protection agent comprises vinylene carbonate.

[0016] The electrolyte, the electrolyte further comprises a solvent and an electrolyte salt, and the concentration of the electrolyte salt is 0.1-10 mol / L.

[0017] The electrolyte, the solvent comprises one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, 1,3-dioxolane, methyl acetate, ethyl acetate, ethyl propionate, propyl propionate, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and bis (2,2,2-trifluoroethyl) ether.

[0018] The electrolyte, the electrolyte salt comprises one or more of sodium hexafluorophosphate, sodium perchlorate, sodium bis (trifluoromethylsulfonyl) imide, sodium bis (fluorosulfonyl) imide, sodium triflate, sodium difluoro oxalate borate, sodium bisoxalate borate, sodium hexafluoroarsenate, sodium tetrafluoroborate, sodium nitrate, and sodium chloride.

[0019] The application further provides a battery comprising the electrolyte.

[0020] The application further provides a battery pack comprising the battery.

[0021] The battery, the battery is a sodium ion battery.

[0022] The application further provides an electric device comprising the battery or the battery pack.

[0023] The electrolyte provided by the application can ensure that the generated film is rich in inorganic substances such as fluoride (such as NaF) and silicon oxide, and has better stability, and the compound shown as formula (1) can inhibit the premature decomposition of erythritol disulfate, make the formation of SEI film more uniform, and further improve the stability, in addition, the compound shown as formula (1) can also react with HF generated in the battery cycle process, reduce the damage to the SEI film, and the decomposition product of erythritol disulfate is relatively stable, which can also further reduce the damage of the decomposition product to the SEI film, through the synergistic effect of the above self-strengthening and reducing external influence, the SEI film formed by using the electrolyte has better stability, thereby improving the cycle performance, especially the high-pressure cycle performance, and the safety performance of the battery. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing specific embodiments only and is not intended to be limiting of the application.

[0026] In the present application, the numerical interval (i.e. numerical range) is designed, and without special instructions, the distribution of the selected values in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e. minimum value and maximum value) of the numerical interval, and each value between the two numerical endpoints.

[0027] Based on the problem that the SEI film formed by the existing electrolyte is not stable enough, thereby affecting the cycle performance and safety performance of the battery, the present application provides a new electrolyte, which includes an additive, and the additive includes a first film-forming agent, and the first film-forming agent includes erythritol disulfate and a compound shown as formula (1):

[0028] Formula (1);

[0029] wherein R1-R3 are independently selected from at least one of H, substituted or unsubstituted C1-C30 alkyl, R4-R6 are independently selected from at least one of H, F and at least one F in R4-R6.

[0030] Firstly, the compound represented by the above formula (1) can induce the formation of SEI film rich in fluoride (such as NaF) and silicon oxide, and the S element introduced in erythritol disulfate can make the SEI film more three-dimensional, thereby ensuring that the generated SEI film has good stability; secondly, the F atom with larger electronegativity in formula (1) can effectively reduce the electron cloud density of the atoms (especially the carbon atoms of erythritol disulfate connected thereto) near the sulfate group, reduce the reaction rate of nucleophilic reaction, inhibit the premature decomposition of erythritol disulfate, and make the formation of SEI film more uniform; in addition, the compound of formula (1) can also react with hydrogen fluoride (HF) generated during the battery cycle process, reduce the destructive effect of HF on the SEI film, and the decomposition products of erythritol disulfate are mainly stable sulfates. Compared with the unstable sulfites formed by conventional vinyl sulfate, it is more stable and is not easy to be further oxidized in the subsequent cycle, which can reduce the corrosion of the positive electrode. Through the above synergistic effect, the SEI film formed by using the electrolyte has better stability, which is conducive to improving the high-pressure cycle performance and safety performance of the battery.

[0031] In the above, the structure of erythritol disulfate is shown in the following formula (2):

[0032] Formula (2).

[0033] In the above, the C1-C30 alkyl includes at least one of linear alkyl, branched alkyl, and cyclic alkyl, for example, C1-C30 linear alkyl, branched alkyl alkyl can include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-triacontyl, isopropyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 2-methylbutyl, 1-ethylpropyl, neopentyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, etc. The substituent group is not limited, for example, it can be a hydroxyl group, a carboxyl group, an aldehyde group, a carbonyl group, an ether group, an amino group, a cyano group, a halogen atom (such as F, Cl, Br, etc.), an aryl group or a heteroaryl group, a sulfonic acid group, an acyl group, etc. Such groups can participate in the formation of the film and ensure the structural stability of the formed film.

[0034] C1-C30 cycloalkyl groups include monocyclic cycloalkyl groups, polycyclic cycloalkyl groups, and the like, examples of which are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cycloundecyl, and the like. The substituents are also not limited, examples of which can be hydroxyl, carboxyl, aldehyde, carbonyl, ether, amino, cyano, halogen atoms (such as F, Cl, Br, and the like), aryl or heteroaryl, sulfonic acid, acyl, and the like. Such groups can also participate in the formation of the film and ensure the structural stability of the formed film.

[0035] In one embodiment, R1-R3 are independently selected from substituted or unsubstituted C1-C4 alkyl groups. Firstly, such raw materials are widely available and easy to prepare, and secondly, their shorter carbon chains can reduce organic decomposition products, thereby reducing the thickness of the organic layer in the SEI film and reducing the energy barrier for the passage of carrier ions (such as Na + , Li + ) through. In one embodiment, R4-R6 are all F, and the introduction of more F is conducive to the formation of more structurally stable products (such as NaF), thereby further increasing the stability of the film.

[0036] Studies have shown that when the mass fraction of the compound of formula (1) in the electrolyte is 0.5-5%, the cycle performance of the battery is better. For example, the mass fraction of the compound of formula (1) in the electrolyte can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, or any value between any two of the above ranges, and the mass fraction of the compound of formula (1) in the electrolyte can also be 0.5-3%.

[0037] The mass fraction of the above erythritol bisulfate in the electrolyte is 0.1-5%, and the erythritol bisulfate in the above addition range is conducive to the formation of an SEI film with moderate thickness and better performance, thereby further improving the cycle performance of the battery. For example, it can be 0.1, 0.5%, 1%, 2%, 2.5%, 3%, 4%, 5%, or any value between any two of the above ranges, and the mass fraction of the erythritol bisulfate in the electrolyte can be 0.5-3%.

[0038] The above additive can also include other commonly used additive substances in batteries, such as a second film-forming agent, a flame retardant, a water removal agent, an overcharge protection agent, and the like.

[0039] For example, the second film-forming agent can include at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propane sulfolane (PS), propylene sulfite (DTD), propylene-1,3-sulfonic acid lactone (PST), and methane disulfite (MMDS), and the addition of the second film-forming agent is conducive to further improving the quality of the SEI film, and thereby further improving the cycle life of the battery.

[0040] The flame retardant can include at least one of trimethyl phosphate (TMP), ethoxy (pentafluoro) cyclo-triphosphazene. By adding the flame retardant, the thermal runaway of the battery can be delayed, thereby improving the safety performance of the battery.

[0041] The water removal agent can include at least one of butanedinitrile (SN), hexanedinitrile (ADN). The addition of the water removal agent is beneficial to reduce the water content in the electrolyte and improve the storage performance of the battery.

[0042] The overcharge protection agent can include vinylene carbonate (VC). The addition of the overcharge protection agent is beneficial to block the current by oxidation and reduction when overcharging, thereby preventing the battery from being damaged by overcharging.

[0043] The mass fraction of the above-mentioned additives in the electrolyte is usually 0.1-50%, which can be adjusted according to the performance requirements of the battery and the electrolyte system. The present application does not make specific limitations.

[0044] It can also be understood that the above-mentioned electrolyte also includes the basic components of the electrolyte, the solvent and the electrolyte salt. The solubility of the electrolyte salt is 0.1-10 mol / L. For example, the concentration of the electrolyte salt can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L and any value between any two of the above-mentioned values.

[0045] In practical applications, the concentration of the electrolyte salt can be appropriately increased, which is beneficial to expand the electrochemical window and further improve the stability of the SEI film.

[0046] The above-mentioned solvent is not specifically limited. For example, it can be selected from one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, 1,3-dioxolane, methyl acetate, ethyl acetate, ethyl propionate, propyl propionate, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, etc.

[0047] The electrolyte salt is not particularly limited, and can be a sodium salt, a lithium salt, or a potassium salt, which can be selected according to the type of the battery. For example, the electrolyte salt can be selected from one or more of sodium hexafluorophosphate, sodium perchlorate, sodium bis(trifluoromethylsulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium triflate, sodium difluoro(oxalato)borate, sodium bis(oxalato)borate, sodium hexafluoroarsenate, sodium tetrafluoroborate, sodium nitrate, sodium chloride, and the like.

[0048] Further, a diluent can be added to the electrolyte to form a local high-concentration electrolyte system, which can further improve the stability of the film while reducing the viscosity of the system. The diluent can be a fluorinated ether and a hydrofluorocarbon, such as hydrofluoroether (HFE), highly fluorinated six-membered ring ether (HFTHP), and the like.

[0049] The present application also provides a battery comprising the electrolyte described above. The type of battery is not particularly limited, and can be a lithium battery, a sodium battery, or a potassium battery, and the like. In addition, the battery can be a liquid battery, a full solid-state battery, or a quasi solid-state battery.

[0050] The type of battery of the present application is not particularly limited, for example, from the perspective of shape, the battery includes, but is not limited to, a square cell, a soft pack battery, and a cylindrical battery, and the like, which are not particularly limited in the present application. From the perspective of the core structure, the core of the battery can be a wound core (i.e., the positive plate, the negative plate, and the separator are stacked and then wound to form the core), or a laminated core (i.e., a plurality of positive plates, negative plates, and separators are stacked to form the core). The shell can be a hard shell (such as a steel shell, a hard plastic shell, etc.), or a soft shell (such as an aluminum plastic film, a bag-type soft shell, etc.), and the like. The present application is not particularly limited.

[0051] The present application also provides a battery pack comprising the battery described above.

[0052] Generally, the battery pack comprises a plurality of batteries described above, which are connected to form a battery pack. The batteries can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or mixed connection comprising both series and parallel connection, and the like, which are not particularly limited. The number of batteries can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0053] The present application also provides an electrical device comprising the battery described above. The electrical device can be a conventional electrical device in the art, including consumer electronics (mobile communication devices, notebook computers, tablet computers, wearable devices, and the like), unmanned aerial vehicles, power tools, energy storage devices, electric bicycles, electric vehicles, and the like.

[0054] The electrolyte described in the present application will be described in detail below with reference to specific examples.

[0055] The experimental methods in the following examples are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0056] Example 1

[0057] Preparation of electrolyte: first, ethylene carbonate and dimethyl carbonate are mixed as main solvents to obtain an electrolyte mother liquor, with a volume ratio of ethylene carbonate: dimethyl carbonate being 1:4. Water in the electrolyte mother liquor is removed by molecular sieves. Then, 1 mol / L sodium hexafluorophosphate is added to the dried and water-free electrolyte mother liquor in batches, and mixed uniformly. After cooling, 1% of erythritol disulfate and 0.5% of the compound of formula (3) are added as the first film-forming additive, to obtain the electrolyte. The compound of formula (3) is as follows:

[0058] .

[0059] Preparation of positive electrode sheet: sodium iron sulfate (NFS) positive electrode material, polyvinylidene fluoride (PVDF) binder, and acetylene black (SuperP) conductive agent are mixed in a mass ratio of 8:1:1, and N-methyl pyrrolidone (NMP) is added to prepare a positive electrode slurry. The solid content of the slurry is adjusted to about 50%, and then the slurry is degassed and sieved, and uniformly coated on the surface of an aluminum foil. After drying, rolling, and cutting, a positive electrode sheet is obtained.

[0060] Preparation of negative electrode sheet: a composite binder composed of hard carbon negative electrode material (HC), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC), and SuperP conductive agent are mixed in a mass ratio of 8:1:1, and deionized water is added to prepare a negative electrode slurry. The solid content of the slurry is adjusted to about 45%, and then the slurry is degassed and sieved, and uniformly coated on the surface of an aluminum foil. After drying, rolling, and cutting, a negative electrode sheet is obtained.

[0061] Preparation of soft-packaged battery: the negative electrode sheet, the separator, and the positive electrode sheet are sequentially stacked into an electric core, which is packaged into an aluminum-plastic shell. After the electric core is baked to remove water, the prepared electrolyte is injected into the soft-packaged battery, and the soft-packaged sodium ion battery is obtained after aging, formation, aging, and capacity distribution.

[0062] Example 2

[0063] The difference between this example and Example 1 is that the mass ratio of the compound of formula (3) in the electrolyte is 1%.

[0064] Example 3

[0065] The difference between this example and Example 1 is that the mass ratio of the compound of formula (3) in the electrolyte is 3%.

[0066] Example 4

[0067] The difference between this example and Example 1 is that the mass percentage of the compound represented by formula (3) in the electrolyte is 5%.

[0068] Example 5

[0069] The difference between this example and Example 2 is that the mass percentage of erythritol disulfate in the electrolyte is 0.1%.

[0070] Example 6

[0071] The difference between this example and Example 2 is that the mass percentage of erythritol disulfate in the electrolyte is 0.5%.

[0072] Example 7

[0073] The difference between this example and Example 2 is that the mass percentage of erythritol disulfate in the electrolyte is 3%.

[0074] Example 8

[0075] The difference between this example and Example 2 is that the mass percentage of erythritol disulfate in the electrolyte is 5%.

[0076] Example 9

[0077] The difference between this example and Example 1 is that the compound represented by formula (4) is used instead of the compound represented by formula (3). The compound represented by formula (4) is as follows:

[0078] .

[0079] Example 10

[0080] The difference between this example and Example 9 is that the mass percentage of the compound represented by formula (4) in the electrolyte is 1%.

[0081] Example 11

[0082] The difference between this example and Example 9 is that the mass percentage of the compound represented by formula (4) in the electrolyte is 5%.

[0083] Example 12

[0084] The difference between this example and Example 10 is that the mass percentage of erythritol disulfate in the electrolyte is 0.5%.

[0085] Example 13

[0086] The difference between this example and Example 10 is that the mass percentage of erythritol disulfate in the electrolyte is 5% and the mass percentage of the compound represented by formula (4) in the electrolyte is 1%.

[0087] Example 14

[0088] The difference between this example and Example 1 is that succinonitrile is further included in the additive, and the mass ratio of succinonitrile in the electrolyte is 1%.

[0089] Example 15

[0090] The difference between this example and Example 1 is that fluoroethylene carbonate is further included in the additive, and the mass ratio of fluoroethylene carbonate in the electrolyte is 1%.

[0091] Example 16

[0092] The difference between this example and Example 1 is that trimethyl phosphate is further included in the additive, and the mass ratio of trimethyl phosphate in the electrolyte is 1%.

[0093] Example 17

[0094] The difference between this example and Example 1 is that vinylene carbonate is further included in the additive, and the mass ratio of vinylene carbonate in the electrolyte is 1%.

[0095] Example 18

[0096] The difference between this example and Example 2 is that the compound shown in formula (5) is used instead of the compound shown in formula (3). The compound shown in formula (5) is as follows:

[0097] .

[0098] Example 19

[0099] The difference between this example and Example 2 is that the compound shown in formula (6) is used instead of the compound shown in formula (3). The compound shown in formula (6) is as follows:

[0100] .

[0101] Comparative Example 1

[0102] The difference between this comparative example and Example 1 is that it does not contain erythritol disulfate and the compound of formula (3).

[0103] Comparative Example 2

[0104] The difference between this comparative example and Example 1 is that it does not contain the compound of formula (3).

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 2 is that it does not contain erythritol disulfate.

[0107] Comparative Example 4

[0108] The present comparative example differs from Example 10 in that it does not contain erythritol bisulfate.

[0109] Comparative Example 5

[0110] The present comparative example differs from Example 2 in that it uses vinyl sulfate instead of erythritol bisulfate.

[0111] Comparative Example 6

[0112] The present comparative example differs from Example 14 in that it does not contain the compound of formula (3).

[0113] Test Example

[0114] The batteries in the above examples and comparative examples were subjected to performance tests, and the test results are shown in Table 1 below.

[0115] Discharge capacity: The batteries were subjected to charge-discharge cycles at a current density of 1C, with a test voltage range of 2.0-4.2V and a test temperature of 25°C, and the initial discharge capacity was recorded.

[0116] Initial efficiency: The batteries were charged to a cutoff voltage (e.g. 4.2V) at a constant current of 1C, and were allowed to stand for a period of time to stabilize the internal state of the battery, and the charge capacity was recorded. The batteries were discharged to a cutoff voltage of 2.5V at a constant current of 1C, and the discharge capacity was recorded. The ratio of the initial discharge capacity to the initial charge capacity is the initial efficiency.

[0117] Capacity retention rate: The batteries were charged to a cutoff voltage (e.g. 4.2V) at a constant current of 1C, and were allowed to stand for a period of time to stabilize the internal state of the battery, and were discharged to a cutoff voltage of 2.5V at a constant current of 1C, and the discharge capacity was recorded, denoted as initial capacity C0. The batteries were subjected to charge-discharge cycles for a specified number of cycles, 500 times. After completing the specified number of cycles, the discharge capacity of the batteries was measured again according to the method for testing the initial capacity, denoted as the capacity after cycling C n . The capacity retention rate was calculated as: capacity retention rate = C n / C0x 100%.

[0118] Table 1

[0119]

[0120] From the above results, it can be seen that the batteries prepared using the electrolytes in Examples 1-19 have better discharge capacity, initial efficiency, and capacity retention rate after 1C cycling for 500 cycles than the batteries in Comparative Examples 1-6, indicating that the addition of erythritol bisulfate and the compound of formula (1) to the electrolyte is beneficial to improving the discharge capacity, initial efficiency, and high-voltage (4.2V) cycling performance of the batteries.

[0121] From the comparison of Example 1 and Example 9, it can be seen that when R1-R3 are the same, the discharge capacity, initial efficiency and high voltage (4.2V) cycle performance of the battery are better when R4-R6 are all F.

[0122] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, characterized by, The electrolyte comprises an additive, the additive comprises a first film-forming agent, the first film-forming agent comprises erythritol disulfate and a compound represented by the following formula (1): Formula (1); Wherein, R1-R3 are independently selected from at least one of H, substituted or unsubstituted C1-C30 alkyl, R4-R6 are independently selected from at least one of H, F, and at least one F in R4-R6.

2. The electrolyte according to claim 1, characterized in that, The R1-R3 are independently selected from at least one of substituted or unsubstituted C1-C4 alkyl.

3. The electrolyte according to claim 1 or 2, characterized in that, The R4-R6 are both F.

4. The electrolyte according to any one of claims 1 to 3, characterized in that, The mass fraction of the compound represented by the formula (1) in the electrolyte is 0.5-5%; and / or The mass fraction of the erythritol disulfate in the electrolyte is 0.1-5%.

5. The electrolyte according to any one of claims 1 to 4, characterized in that, The additive further comprises one or more of a second film-forming agent, a flame retardant, a water removal agent, and an overcharge protection agent.

6. The electrolyte according to claim 5, characterized in that The second film-forming agent comprises at least one of fluoroethylene carbonate, vinylene carbonate, 1,3-propane sulfolactone, propylene sulfite, propenyl-1,3-sulfonic acid lactone, and methane disulfite; and / or The flame retardant comprises at least one of trimethyl phosphate and ethoxy (pentafluoro) cyclo-triphosphazene; and / or The water removal agent comprises at least one of butanedinitrile and hexanedinitrile; and / or The overcharge protection agent comprises vinylene carbonate.

7. The electrolyte according to any one of claims 1 to 6, characterized in that, The electrolyte further comprises a solvent and an electrolyte salt, the concentration of the electrolyte salt in the electrolyte is 0.1-10 mol / L.

8. The electrolyte according to claim 7, characterized in that The solvent comprises one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, 1,3-dioxolane, methyl acetate, ethyl acetate, ethyl propionate, propyl propionate, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and bis(2,2,2-trifluoroethyl) ether; and / or The electrolyte salt comprises one or more of sodium hexafluorophosphate, sodium perchlorate, sodium bis(trifluoromethylsulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium triflate, sodium difluoro oxalate borate, sodium bisoxalate borate, sodium hexafluoroarsenate, sodium tetrafluoroborate, sodium nitrate, and sodium chloride.

9. A battery, characterized by The electrolyte comprises the electrolyte of any one of claims 1-8.

10. The battery of claim 9, wherein, The battery is a sodium ion battery.

11. A battery pack, characterized by The battery comprises the electrolyte of any one of claims 1-8 or the battery of claim 9 or 10.

12. An electrical device, characterized by The battery comprises the battery of claim 9 or 10 or the battery of claim 11.

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