An electrolyte and a battery comprising the same

Abstract

The application provides an electrolyte and a battery comprising the electrolyte. The functional additive A in the electrolyte can combine HF in the electrolyte, reduce the acidity of the system, stabilize the interface of the positive and negative electrode materials, and thus improve the high-temperature performance of the battery; the functional additive B can not only capture the hydroxyl radical and / or hydrogen radical in the electrolyte system when heated, prevent the chain reaction of combustion or explosion of hydrocarbons, and form an inorganic oxygen barrier and heat insulation protective layer, so as to reduce the flammability of the electrolyte, but also can further consume HF, reduce the damage of HF to the interface film, and stabilize LiPF6. When the two contents are used in the limited range, a small-resistance interface film is formed, and thus the low-temperature performance of the battery is not deteriorated. Through the combination and synergistic effect of the two functional additives, the synergistic effect of simultaneously improving the high-temperature performance and safety performance of the battery can be achieved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to an electrolyte with good high-temperature performance and high safety, and a battery containing the electrolyte. Background Technology

[0002] With increasing attention paid to the depletion of non-renewable energy sources and environmental pollution, renewable and clean energy is developing rapidly. Among them, lithium-ion batteries, with their high energy density, long cycle life, low self-discharge rate, and environmental friendliness, are widely used in consumer electronics, new energy vehicles, and other power battery products.

[0003] However, lithium-ion batteries still suffer from poor high-temperature performance and safety issues, limiting their application in power products, especially automotive lithium-ion batteries. The electrical performance of lithium-ion batteries is closely related to the electrolyte. Therefore, based on this bottleneck, researchers have conducted extensive studies. Adding high-temperature additives to the electrolyte can improve the battery's high-temperature performance, but this increases impedance to some extent and degrades the low-temperature performance of lithium-ion batteries. Adding phosphorus-nitrogen composite organic compounds as functional additives to the electrolyte has significantly improved the safety performance of lithium-ion batteries, but most organic phosphorus additives have poor electrochemical stability and are prone to decomposition. Furthermore, current electrolyte systems also have the following problems: the electrolyte lithium salt (LiPF6) is unstable at high temperatures and easily decomposes into HF in the presence of trace amounts of water, causing an increase in electrolyte acidity, damaging electrode materials, and resulting in continuous capacity decay. This is also the main reason for the degradation of lithium-ion battery cycle and storage life at high temperatures. Summary of the Invention

[0004] To address the high-temperature performance and safety issues of lithium-ion batteries, this invention provides an electrolyte and a battery comprising the electrolyte. The electrolyte includes functional additive A and functional additive B, wherein functional additive A can remove HF (Si and F) from the electrolyte. - This combination reduces the damage of HF to electrode materials under high-temperature conditions, and results in lower impedance during film formation at both positive and negative electrodes. Furthermore, functional additive B can further consume HF (-Si=O and F). - Combined, functional additive B reduces the damage of HF to the interface film and stabilizes LiPF6. In addition, functional additive B can form an inorganic oxygen-barrier heat insulation protective layer during battery combustion, shortening the self-extinguishing time. By using functional additive A and functional additive B in combination, the high-temperature performance and safety performance of the battery can be significantly improved without deteriorating the low-temperature performance of the battery.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] An electrolyte comprising an electrolyte salt, an organic solvent, and additives; the additives comprising functional additive A and functional additive B;

[0007] The functional additive A is selected from silane compounds containing isothiocyanate groups; the functional additive B is selected from polysiloxane compounds.

[0008] According to an embodiment of the present invention, the silane compound containing isothiocyanate contains isothiocyanate (-N=C=S) and silane (Si(R1R2R3)-), and the definitions of R1, R2 and R3 are as follows.

[0009] According to an embodiment of the present invention, the polysiloxane compound contains a -Si=O group.

[0010] According to an embodiment of the present invention, the functional additive A is selected from at least one of the compounds shown in Formula 1:

[0011]

[0012] In Formula 1, R1, R2, and R3 may be the same or different, and are independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkoxy, and substituted or unsubstituted lactone groups; if substituted, the substituent is C. 1- C5 alkyl, C2-C5 alkenyl, C2-C5 alkynyl, C3-C5 cycloalkyl or halogen.

[0013] According to an embodiment of the present invention, in Formula 1, R1, R2, and R3 may be the same or different, and are independently selected from substituted or unsubstituted C. 1- C 12 Alkyl, substituted or unsubstituted C 2- C 12 alkenyl, substituted or unsubstituted C 2- C 12 Alkyne, substituted or unsubstituted C 3- C 12 cycloalkyl, substituted or unsubstituted C 3- C 12 Alkoxy, substituted or unsubstituted C 3- C6 lactone group; if substituted, the substituent is C6. 1- C5 alkyl, C2-C5 alkenyl, C2-C5 alkynyl, C3-C5 cycloalkyl or halogen.

[0014] According to an embodiment of the present invention, in Formula 1, R1, R2, and R3 may be the same or different, and are independently selected from substituted or unsubstituted C. 1- C6 alkyl, substituted or unsubstituted C 2-C6 alkenyl, substituted or unsubstituted C 2- C6 ynyl group, substituted or unsubstituted C 3- C6 cycloalkyl, substituted or unsubstituted C 1- C6 alkoxy, substituted or unsubstituted C 3- C5 lactone group; if substituted, the substituent is C. 1- C5 alkyl, C2-C5 alkenyl, C2-C5 alkynyl, C3-C5 cycloalkyl or halogen.

[0015] According to an embodiment of the present invention, in Formula 1, R1, R2, and R3 may be the same or different, and are independently selected from substituted or unsubstituted C. 1- C3 alkyl, substituted or unsubstituted C 2- C3 alkenyl, substituted or unsubstituted C 2- C3 ynyl group, substituted or unsubstituted C 3- C4 cycloalkyl, substituted or unsubstituted C 1- C3 alkoxy, substituted or unsubstituted C 3- C4 lactone group; if substituted, the substituent is C. 1- C3 alkyl, C2-C3 alkenyl, C2-C3 alkynyl, C3-C4 cycloalkyl or halogen.

[0016] According to an embodiment of the present invention, the functional additive A is selected from at least one of the following compounds I to VI:

[0017]

[0018]

[0019] According to an embodiment of the present invention, the functional additive B is selected from at least one of the compounds shown in Formula 2:

[0020]

[0021] In Formula 2, R4 and R5 may be the same or different, and are independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; if substituted, the substituent is C. 1- C5 alkyl or halogen.

[0022] According to an embodiment of the present invention, in Formula 2, R4 and R5 may be the same or different, and are independently selected from substituted or unsubstituted C. 1- C 12 Alkyl, substituted or unsubstituted C 6- C 14 Aryl; if substituted, the substituent is C. 1- C5 alkyl or halogen.

[0023] According to an embodiment of the present invention, in Formula 2, R4 and R5 may be the same or different, and are independently selected from substituted or unsubstituted C. 1- C6 alkyl, substituted or unsubstituted C 6- C 12 Aryl; if substituted, the substituent is C. 1- C5 alkyl or halogen.

[0024] According to an embodiment of the present invention, in Formula 2, R4 and R5 may be the same or different, and are independently selected from substituted or unsubstituted C. 1- C3 alkyl, substituted or unsubstituted C 6- C8 aryl; if substituted, the substituent is C. 1- C3 alkyl or halogen.

[0025] According to an embodiment of the present invention, the functional additive B is selected from at least one of the following compounds VII to IX:

[0026]

[0027] According to an embodiment of the present invention, the electrolyte salt is selected from lithium electrolyte salts, and the lithium electrolyte salt is selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalateborate)borate, and lithium di(fluorooxalateborate).

[0028] According to an embodiment of the present invention, the additive further includes a functional additive C, wherein the functional additive C is selected from at least one of vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene ethylene carbonate (VEC), ethylene sulfate (DTD), 1,3-propanesulfonyl lactone (PS), ethylene sulfite (ES), tris(trimethylsilane)borate (TMSB), tris(trimethylsilane) phosphate (TMSP), lithium bis(oxalato)borate (LiBOB), lithium difluorooxalatoborate (LiODFB), and lithium difluorodioxalatophosphate (LiODFP).

[0029] According to embodiments of the present invention, the organic solvent is selected from at least two of the following: propylene carbonate, methyl ethyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, γ-butyrolactone, sulfolane, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, and butyl butyrate.

[0030] According to an embodiment of the present invention, functional additive A and functional additive B are both compounds known in the art, which can be prepared by methods known in the art or obtained through commercial purchase.

[0031] According to an embodiment of the present invention, the functional additive A accounts for 0.5wt% to 4wt% of the total mass of the electrolyte, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, or 4wt%.

[0032] According to an embodiment of the present invention, the functional additive B accounts for 0.5 wt% to 3 wt% of the total mass of the electrolyte, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%.

[0033] According to an embodiment of the present invention, the mass percentage of the electrolyte salt in the total mass of the electrolyte is 12wt% to 18wt%, for example, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, or 18wt%.

[0034] According to an embodiment of the present invention, the functional additive C accounts for 0.5 wt% to 3 wt% of the total mass of the electrolyte, for example, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%.

[0035] According to an embodiment of the present invention, the organic solvent accounts for 10 wt% to 80 wt% of the total mass of the electrolyte, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt%.

[0036] The present invention also provides a battery comprising the electrolyte described above.

[0037] According to an embodiment of the present invention, the battery is a lithium-ion battery.

[0038] According to an embodiment of the present invention, the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.

[0039] According to an embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer coated on one or both surfaces of the positive current collector, wherein the positive active material layer includes a positive active material, a conductive agent, and a binder.

[0040] According to an embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both surfaces of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder.

[0041] According to an embodiment of the present invention, the mass percentage of each component in the positive electrode active material layer is: 80-99.8 wt% positive electrode active material, 0.1-10 wt% conductive agent, and 0.1-10 wt% binder.

[0042] Preferably, the mass percentage of each component in the positive electrode active material layer is: 90-99.6 wt% positive electrode active material, 0.2-5 wt% conductive agent, and 0.2-5 wt% binder.

[0043] According to an embodiment of the present invention, the mass percentage of each component in the negative electrode active material layer is: 80-99.8 wt% negative electrode active material, 0.1-10 wt% conductive agent, and 0.1-10 wt% binder.

[0044] Preferably, the mass percentage of each component in the negative electrode active material layer is: 90-99.6 wt% negative electrode active material, 0.2-5 wt% conductive agent, and 0.2-5 wt% binder.

[0045] According to an embodiment of the present invention, the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, and metal powder.

[0046] According to an embodiment of the present invention, the adhesive is selected from at least one of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0047] According to an embodiment of the present invention, the positive electrode active material is selected from at least one of lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide ternary materials, lithium nickel manganese oxide, and lithium-rich manganese-based materials.

[0048] According to an embodiment of the present invention, the negative electrode active material is selected from at least one of graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-based negative electrode materials and lithium-containing metal composite oxide materials.

[0049] The beneficial effects of this invention are:

[0050] This invention provides an electrolyte and a battery comprising the electrolyte. Functional additive A in the electrolyte can bind HF in the electrolyte, reducing the acidity of the system and stabilizing the interface between the positive and negative electrode materials, thereby improving the high-temperature performance of the battery. Functional additive B not only captures hydroxyl radicals and / or hydrogen radicals in the electrolyte system when heated, preventing chain reactions of hydrocarbon combustion or explosion, and forming an inorganic oxygen-barrier heat-insulating protective layer, thereby reducing the flammability of the electrolyte, but also further consumes HF, reducing the damage of HF to the interface film and stabilizing LiPF6. When both are used in combination within a defined range, an interface film with low impedance is formed, thus not degrading the low-temperature performance of the battery. Through the combined use and synergistic effect of the two functional additives, a synergistic effect of simultaneously improving the high-temperature performance and safety performance of the battery can be achieved. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0052] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0053] Lithium-ion battery manufacturing

[0054] (1) Preparation of positive electrode

[0055] The positive electrode active material lithium nickel cobalt manganese oxide (NCM613), binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black were mixed in a weight ratio of 96.5:2:1.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until a uniform and fluid positive electrode slurry was formed. The positive electrode slurry was uniformly coated onto an aluminum foil with a thickness of 7 μm. The coated aluminum foil was baked in an oven with 5 different temperature gradients, and then dried in an oven at 120°C for 8 hours. After that, the positive electrode sheet was obtained by rolling and slitting.

[0056] (2) Preparation of negative electrode sheet

[0057] Artificial graphite (anode active material), sodium carboxymethyl cellulose (CMC-Na) (thickener), styrene-butadiene rubber (binder), acetylene black (conductive agent), and single-walled carbon nanotubes (SWCNTs) (conductive agent) were mixed in a weight ratio of 95.9:1:2:1:0.1. Deionized water was added, and the mixture was stirred in a vacuum mixer to obtain anode slurry. The anode slurry was uniformly coated onto a copper foil with a thickness of 6 μm. After drying (temperature: 85℃, time: 5h), rolling and die-cutting, anode sheets were obtained.

[0058] (3) Electrolyte preparation

[0059] In an argon-filled glove box (moisture <10ppm, oxygen <1ppm), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed uniformly in a mass ratio of 25:5:65:5. Sufficiently dried lithium salt (14.5wt% based on the total mass of the electrolyte) and a certain amount of additives (specific selection and dosage are shown in Table 1) were quickly added to the mixed solution and stirred until homogeneous to obtain the electrolyte.

[0060] (4) Preparation of the diaphragm

[0061] An 8μm thick coated polyethylene diaphragm was selected.

[0062] (5) Preparation of lithium-ion batteries

[0063] The prepared positive electrode sheet, separator, and negative electrode sheet are wound to obtain a bare cell without electrolyte injection; the bare cell is placed in an outer packaging foil, and the prepared electrolyte is injected into the dried bare cell. After vacuum sealing, standing, formation, shaping, and sorting, the desired lithium-ion battery is obtained.

[0064] Comparative Examples 1-3 and Examples 1-19

[0065] The lithium-ion batteries of Comparative Examples 1-3 and Examples 1-19 were all prepared according to the above preparation method, and the specific differences are shown in Table 1.

[0066] Table 1. Parameter information of lithium-ion batteries prepared in comparative examples and embodiments.

[0067]

[0068] The electrochemical performance of the lithium-ion batteries obtained in the comparative examples and embodiments above was tested:

[0069] (1) HF acidity test: A standard sodium hydroxide titration solution with a molar concentration of approximately 0.01 mol / L and a bromothymol blue indicator solution (prepared by mixing 0.1 g BTB with 100 ml anhydrous ethanol) with a mass concentration of 0.4 g / L were used to determine the HF content. The determination process is as follows: In a beaker, prepare an ice-water solution with 20 g crushed ice and 10 g deionized water, add a magnetic stir bar, place it on a stirring table, and stir at medium speed. Add 2-3 drops of bromothymol blue (BTB) indicator to the ice-water solution using a dropper, stir for about 10 seconds, press the power button to turn on the titrator, and slowly rotate the titrator knob counterclockwise to allow the 0.01 M NaOH solution to fall drop by drop. When the solution turns blue and does not fade for a long time, press the "CLEAR" button to return to zero. Take 2-3g of sample using a disposable syringe, deduct the tare weight on a top-loaded balance, and then quickly inject the sample into ice water. Slowly rotate the titrator knob counterclockwise to allow the NaOH solution to fall drop by drop. The titration endpoint is reached when the solution turns blue and remains so for at least 3 seconds. Record the titrator reading, which is the volume V of the 0.01M NaOH solution used. Weigh the syringe again and obtain the sample weight m by the difference. Before titrating the sample, carefully rinse the titrator outlet tip with the titrant. The formula for calculating the free acidity of HF is:

[0070] E = (0.02 × V × n × 10⁶) / m

[0071] E: Free acidity of HF (ppm);

[0072] V: Volume (ml) of 0.01M NaOH;

[0073] n: The actual equivalent concentration of 0.01M NaOH (Note: In actual preparation, n≠0.01M, and the precise concentration is obtained by titration with potassium hydrogen phthalate standard solution).

[0074] m: Sample weight (g)

[0075] (2) 0℃ Cycling: The obtained battery was placed in an environment of (0±2)℃ and left to stand for 2-3 hours. When the battery body reached (0±2)℃, the battery was charged at a constant current and constant voltage of 0.2C to the upper limit voltage of 4.25V, and the cutoff current was 0.05C. After the battery was fully charged, it was left to rest for 5 minutes, and then discharged at a constant current of 0.5C to the cutoff voltage of 3.0V. The highest discharge capacity of the first 3 cycles was recorded as the initial capacity Q1. When the cycle reached 300 cycles, the discharge capacity Q2 of the last cycle was recorded. The results are shown in Table 2. The calculation formulas used are as follows:

[0076] Capacity retention rate (%) = Q2 / Q1 × 100%

[0077] (3) 55℃ Cycling: The obtained battery was placed in an environment of (55±2)℃ and left to stand for 2-3 hours. When the battery body reached (55±2)℃, the battery was charged at 1C constant current and constant voltage to the upper limit voltage of 4.25V, and the cutoff current was 0.05C. After the battery was fully charged, it was left to rest for 5 minutes, and then discharged at 1C constant current to the cutoff voltage of 3.0V. The highest discharge capacity of the first 3 cycles was recorded as the initial capacity Q3. When the cycle reached 500 cycles, the discharge capacity Q4 of the last cycle was recorded. The results are shown in Table 2. The calculation formulas used are as follows:

[0078] Capacity retention rate (%) = Q4 / Q3 × 100%

[0079] (4) 85℃ Storage: The obtained battery was placed in an environment of (25±2)℃, and the thickness T1 of the fully charged cell was measured. After formation, the battery was charged at 1C constant current and constant voltage to the upper limit voltage of 4.25V, with a cutoff current of 0.05C. Then, it was discharged at 1C constant current to 3.0V, and then charged at 1C constant current and constant voltage to the upper limit voltage of 4.25V, with a cutoff current of 0.05C. After being placed in an environment of 85℃ for 8 hours, the fully charged thickness T2 was measured, and the thickness change rate (%) was calculated. The results are shown in Table 2. The calculation formulas used are as follows:

[0080] Thickness change rate (%) = (T2-T1) / T1*100%.

[0081] (5) Flame retardant test: The ceramic boat was thoroughly cleaned and dried. The combustion aid was placed at the bottom of the ceramic boat and flattened. Electrolyte was added to the ceramic boat and then ignited. The time from when the fire source was removed until the electrolyte was extinguished was recorded as the self-extinguishing time. The shorter the self-extinguishing time, the better. The results are shown in Table 2.

[0082] Table 2. Performance test results of lithium-ion batteries in comparative and example cases.

[0083]

[0084] The results from Comparative Examples 1-3 and Example 2 show that the combined use of functional additives A and B can significantly reduce the HF acidity in the electrolyte system and shorten the self-extinguishing time, thereby significantly improving high-temperature and safety performance without deteriorating low-temperature performance. The results from Examples 1-19 show that the optimal content range of functional additive A is 0.5wt%-4wt%. The possible mechanism for this effect is that when the content of functional additive A is too low, it cannot effectively remove HF from the electrolyte, resulting in no significant performance improvement. When the content of functional additive A is too high, although it can significantly improve high-temperature performance, it will increase interfacial impedance, thus… The low-temperature performance is deteriorated. The optimal content range of functional additive B is 0.5wt%-3wt%. The possible mechanism for this effect is that when the content of functional additive B is too low, an effective inorganic oxygen-barrier thermal insulation layer cannot be formed; when the content of functional additive B is too high, it may increase the interfacial impedance and electrolyte viscosity, thereby deteriorating the low-temperature performance. Comparative Examples 2, 2, and 10-12 show that when the content of functional additive A is fixed, the HF content in the electrolyte system decreases to a certain extent with the addition and increase of functional additive B. The possible mechanism for this effect is that functional additive B can bind HF... - This further removes the small amount of HF that has formed, thereby reducing the HF content.

[0085] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrolyte, characterized by, The electrolyte comprises an electrolyte salt, an organic solvent and an additive; the additive comprises a functional additive A and a functional additive B; The functional additive A is selected from silane compounds containing isothiocyanide; the functional additive B is selected from polysiloxane compounds; The functional additive A is selected from at least one of the compounds shown in Formula 1: Formula 1 In formula 1, R1, R2and R3are the same or different and independently of each other selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted lactone; if substituted, the substituents are C 1- C5alkyl, C2-C5alkenyl, C2-C5alkynyl, C3-C5cycloalkyl, or halogen; The functional additive B is selected from at least one of the compounds shown in Formula 2: Formula 2 In formula 2, R4and R5are the same or different, and are independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted aryl; if substituted, the substituent is C 1- C5alkyl or halogen; The mass percentage of the functional additive A in the total mass of the electrolyte is 0.5wt%-4wt%; The mass percentage of the functional additive B in the total mass of the electrolyte is 0.5wt%-3wt%.

2. The electrolyte according to claim 1, characterized in that, In formula 1, R1, R2and R3are the same or different and independently of one another selected from substituted or unsubstituted C 1- C 12 alkyl, substituted or unsubstituted C 2- C 12 alkenyl, substituted or unsubstituted C 2- C 12 alkynyl, substituted or unsubstituted C 3- C 12 cycloalkyl, substituted or unsubstituted C 3- C 12 alkoxy, substituted or unsubstituted C 3- C6lactone group; if substituted, the substituents are C 1- C5alkyl, C2-C5alkenyl, C2-C5alkynyl, C3-C5cycloalkyl or halogen.

3. The electrolyte according to claim 2, characterized in that, The functional additive A is selected from at least one of the compounds shown in Formula 1: Compound I Compound II Compound III Compound IV Compound V Compound VI.

4. The electrolyte of claim 1, wherein In formula 2, R4and R5are the same or different and independently of each other selected from substituted or unsubstituted C 1- C 12 alkyl, substituted or unsubstituted C 6- C 14 aryl; if substituted, the substituents are C 1- C5alkyl or halogen.

5. The electrolyte according to claim 4, characterized in that The functional additive B is selected from at least one of the compounds shown in Formula 2: Compound VII Compound VIII Compound IX.

6. The electrolyte according to any one of claims 1 to 5, characterized in that, The additive further comprises a functional additive C, the functional additive C is selected from at least one of the following compounds: vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, ethylene sulfate, 1,3-propane sultone, vinyl sulfite, tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorodioxalate phosphate; the mass percentage of the functional additive C in the total mass of the electrolyte is 0.5wt%-3wt%.

7. A battery, characterized by The battery comprises the electrolyte according to any one of claims 1-6.

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