Electrolyte and battery

Abstract

This application relates to the field of battery technology, specifically to an electrolyte and a battery. The electrolyte of this invention comprises an organic solvent, a lithium salt, additive A, additive B, and additive C; additive A is a carbodisulfonate; additive B is a polycyano nitrile compound; and additive C is a bis(fluorosulfonyl)imide salt. This electrolyte improves the safety performance of the battery at high temperatures, has a simple process, low cost, and good protective effect.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an electrolyte and a battery. Background Technology

[0002] Lithium-ion batteries are widely used in 3C digital products, power tools, electric vehicles, and other fields due to their advantages such as high operating voltage, high energy density, long lifespan, and environmental friendliness. Especially in the 3C digital field, the trend towards lighter and thinner mobile electronic devices such as smartphones and power banks in recent years has made lithium-ion batteries increasingly popular.

[0003] A lithium-ion battery is a rechargeable battery that primarily functions by the movement of lithium ions between the positive and negative electrodes. During charging and discharging, Li... + Intercalation and deintercalation back and forth between the two electrodes: During charging, Li + Lithium is extracted from the positive electrode and inserted into the negative electrode through the electrolyte, placing the negative electrode in a lithium-rich state; the process is reversed during discharge. The electrolyte, as one of the main components of a lithium-ion battery, plays an indispensable role and is often referred to as the "blood" of the battery. However, the most critical part of the lithium-ion battery electrolyte is the additives, such as negative electrode film-forming additives, positive electrode film-forming additives, stabilizers, dehydrating agents, and deacidifying agents.

[0004] Generally, sulfur-containing additives can reduce battery impedance, thereby improving the battery's high-temperature and low-temperature performance. 1,3-propanesulfonyl lactone (PS), a representative sulfur-containing additive, has the following structural formula:

[0005]

[0006] PS is a film-forming additive that reduces battery impedance. However, due to the carcinogenicity of PS additives, the EU has very strict controls on their use. After the electrolyte is injected into the battery and the product is manufactured, random sampling tests are conducted to check the content of PS additives (Reach test).

[0007] However, the sulfur-containing additive ethylene sulfate (DTD) has poor thermal stability. Without the presence of a stabilizer, it will lead to the deterioration of the electrolyte's acid value and color, thereby affecting the battery's high-temperature performance.

[0008] Therefore, it is imperative to develop new high-temperature additives that can replace additives such as PS. Summary of the Invention

[0009] In view of this, the present invention provides an electrolyte and a battery. This electrolyte improves the safety performance of the battery at high temperatures, has a simple process, low cost, and good protective effect.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0011] This invention provides an electrolyte comprising an organic solvent, a lithium salt, additive A, additive B, and additive C;

[0012] Additive A is a carbodisulfonate;

[0013] Additive B is a polycyano nitrile compound;

[0014] Additive C is a difluorosulfonyl imide salt.

[0015] In this invention, "carbon-linked disulfonate" refers to a sulfonate compound having at least two rings. In a specific embodiment of this invention, the two cyclic sulfonate compounds are symmetrical, enabling them to preferentially form films at the negative electrode compared to the solvent, while also forming films at the positive electrode, thereby reducing LiF content and improving ion conduction performance.

[0016] In this invention, "polycyano nitrile compounds" refers to nitrile compounds having two or more cyano groups.

[0017] As a preferred option, additive A has the following general structural formula:

[0018]

[0019] Among them, R1 and R2 are each independently selected from:

[0020] C1–20 alkane, alkene, and alkyne groups, whether halogenated or unsubstituted.

[0021] C3–C20 cycloalkyl groups, whether halogenated or unsubstituted.

[0022] Phenyl groups, whether halogenated or unsubstituted,

[0023] Biphenyl compounds, whether halogenated or unsubstituted,

[0024] C6–C26 benzenealkyl groups, whether halogenated or unsubstituted.

[0025] C6–C26 fused-ring aromatic groups, substituted or unsubstituted with halogens.

[0026] Hydrogen or halogen atom substituents;

[0027] Preferably, R1 and R2 are each independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl.

[0028] Among them, A1, A2, A3, A4, C1, and C2 represent independent atoms, each independently selected from C, S, N, and O;

[0029] Preferably, A1 and A4 are each independently selected from C, N, and O.

[0030] Preferably, A2, A3, C1, and C2 are each independently selected from N and O.

[0031] Where n is the number of carbon atoms between 0 and 2.

[0032] Preferably, n is 1.

[0033] In specific embodiments provided by the present invention, additive A includes at least one of the following structural formulas 1 to 12:

[0034]

[0035]

[0036] Preferably, the polycyano nitrile compounds include at least one of succinic anionyl nitrile, glutaronitrile, adiponitrile (ADN), caprylyl nitrile, sebacate, 3-methoxypropionitrile, ethylene glycol bis(propionitrile) ether, 1,3,6-hexanetrionitrile (HTCN), 1,2,3-tris-(2-cyanoethoxy)propane, 1,3,5-pentanetriformitrile, 2,2-difluorosuccinic anionyl nitrile, 2-fluoroadiponitrile, and tricyanobenzene.

[0037] Preferably, the polycyano nitrile compounds include adiponitrile and 1,3,6-hexanetrionitrile.

[0038] Preferably, the mass ratio of adiponitrile to 1,3,6-hexanetrionitrile is (1-100):(1-100).

[0039] Preferably, the mass ratio of adiponitrile to 1,3,6-hexanetrionitrile is (1-10):(1-10).

[0040] In a specific embodiment provided by the present invention, the mass ratio of adiponitrile to 1,3,6-hexanetrionitrile is 1:1.

[0041] As a preferred embodiment, the bis(fluorosulfonyl)imide salt has the following structural formula:

[0042]

[0043] R3 is selected from one of Li, Na, K, Rb, Cs, and Fr.

[0044] Preferably, the difluorosulfonyl imide salt includes at least one of lithium difluorosulfonyl imide, sodium difluorosulfonyl imide, potassium difluorosulfonyl imide, rubidium difluorosulfonyl imide, and cesium difluorosulfonyl imide.

[0045] The structural formula of lithium bis(fluorosulfonyl)imide is:

[0046]

[0047] The structural formula of sodium difluorosulfonamide is:

[0048]

[0049] The structural formula of potassium difluorosulfonylimide is:

[0050]

[0051] The structural formula of rubidium difluorosulfonylimide is:

[0052]

[0053] The structural formula of bis(fluorosulfonyl)imide cesium is:

[0054]

[0055] Preferably, the content of additive A in the electrolyte is 0.1 wt% to 5.0 wt%; for example, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 1.3 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.3 wt%, 3.5 wt%, 3.8 wt%, 4 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, or 5.0 wt%.

[0056] Preferably, the content of additive A is 1.0 wt% to 4.0 wt%.

[0057] Preferably, the content of additive B is 0.1 wt% to 5.0 wt%; for example, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 1.3 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.3 wt%, 3.5 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, or 5 wt%.

[0058] Preferably, the content of additive B is 0.1 wt% to 3.9 wt%.

[0059] More preferably, the content of additive B is 0.1 wt% to 3.0 wt%.

[0060] Preferably, the content of additive C is 0.5 wt% to 10 wt%. For example, it is 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 1.3 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.3 wt%, 3.5 wt%, 3.8 wt%, 4 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%.

[0061] Preferably, the content of additive C is 2.0 wt% to 7.0 wt%.

[0062] Preferably, the electrolyte satisfies the following relationship:

[0063] 0.36≤(C B +0.5C A ) / (C C -0.5C A )≤4

[0064] Among them, C A C represents the mass percentage of additive A in the electrolyte. B C represents the mass percentage of additive B in the electrolyte; C Let C be the mass percentage of additive C in the electrolyte, where 1 ≤ C. A ≤4, 0.1≤C B ≤3, 2≤C C ≤7.

[0065] Preferably, the electrolyte further includes additive D, which includes at least one of fluoroethylene carbonate, 1,3-propenesulfonate lactone, ethylene sulfate, lithium difluorooxalate borate, lithium difluorophosphate, and lithium difluorodioxalate phosphate.

[0066] Preferably, additive D includes fluoroethylene carbonate and 1,3-propenesulfonate lactone.

[0067] Preferably, the content of fluoroethylene carbonate is 1 wt% to 10 wt%.

[0068] Preferably, the content of 1,3-propenesulfonate lactone is 1 wt% to 3 wt%.

[0069] Preferably, the lithium salt is selected from at least one of lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide, lithium difluorobis(oxalate)phosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium hexafluoroantimonyate, lithium hexafluoroarsenate, lithium di(trifluoromethanesulfonyl)imide, lithium di(pentafluoroethylsulfonyl)imide, lithium tri(trifluoromethanesulfonyl)methyl, or lithium di(trifluoromethanesulfonyl)imide.

[0070] Preferably, the concentration of lithium salt in the electrolyte is 1.0–1.5 mol / L.

[0071] Preferably, the organic solvent is selected from carbonates and / or carboxylic esters.

[0072] Preferably, the carbonate is selected from one or more of the following fluorinated or unsubstituted solvents: ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate, diethyl carbonate (DEC), and methyl ethyl carbonate.

[0073] Preferably, the carboxylic acid ester is selected from one or more of the following fluorinated or unsubstituted solvents: propyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, propyl propionate (PP), ethyl propionate (EP), methyl butyrate, and ethyl n-butyrate.

[0074] In the specific embodiments provided by the present invention, when the organic solvent includes multiple components, the components can be combined in any proportion.

[0075] The present invention also provides a method for preparing the above-mentioned electrolyte, wherein an organic solvent, lithium salt, additive A, additive B and additive C are mixed to obtain an electrolyte.

[0076] In a specific embodiment provided by the present invention, the electrolyte further includes additive D, and the preparation method of the electrolyte includes: mixing organic solvent, lithium salt, additive A, additive B, additive C and additive D to obtain the electrolyte.

[0077] The present invention also provides a battery comprising the above-described electrolyte.

[0078] In the embodiments provided by the present invention, the battery further includes a positive electrode, a negative electrode, and a separator.

[0079] In the embodiments provided by 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.

[0080] Preferably, the mass percentage contents of the components in the positive electrode active material layer are as follows: 80 wt% to 99.8 wt% of positive electrode active material, 0.1 wt% to 10 wt% of conductive agent, and 0.1 wt% to 10 wt% of binder.

[0081] Preferably, the mass percentage contents of the components in the positive electrode active material layer are as follows: 90 wt% to 99.6 wt% of positive electrode active material, 0.2 wt% to 5 wt% of conductive agent, and 0.2 wt% to 5 wt% of binder. <X

[0082] In the embodiments provided by 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, and the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder.

[0083] Preferably, the mass percentage contents of the components in the negative electrode active material layer are as follows: 80 wt% to 99.8 wt% of negative electrode active material, 0.1 wt% to 10 wt% of conductive agent, and 0.1 wt% to 10 wt% of binder.

[0084] Preferably, the mass percentage contents of the components in the negative electrode active material layer are as follows: 90 wt% to 99.6 wt% of negative electrode active material, 0.2 wt% to 5 wt% of conductive agent, and 0.2 wt% to 5 wt% of binder.

[0085] Preferably, the negative electrode active material includes a carbon-based negative electrode material.

[0086] Preferably, the carbon-based negative electrode material includes at least one of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, and soft carbon.

[0087] In the embodiments provided by the present invention, the negative electrode active material may further include a silicon-based negative electrode material.

[0088] In the specific embodiments provided by the present invention, the silicon-based negative electrode material is selected from at least one of nano-silicon, silicon oxide negative electrode material (SiO x (0 < x < 2)), or silicon-carbon negative electrode material.

[0089] In the specific embodiments provided by the present invention, in the negative electrode active material, the mass ratio of the carbon-based negative electrode material to the silicon-based negative electrode material is 10:0 to 1:19, such as 1:19, 1:18, 1:17, 1:16, 1:15, 1:14, 1:13, 1:12, 1:11, 1:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, or 10:0.

[0090] Preferably, the positive electrode active material is selected from one or more of transition metal lithium oxides, lithium iron phosphate, and lithium manganese oxide; the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; where M is one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.

[0091] Preferably, the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, metal powder, and carbon fiber.

[0092] Preferably, the adhesive is selected from at least one of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0093] In a specific embodiment provided by the present invention, the battery also includes an outer packaging.

[0094] In a specific embodiment provided by the present invention, the battery is prepared by: stacking a positive electrode sheet, a separator, and a negative electrode sheet to obtain a battery cell, or stacking a positive electrode sheet, a separator, and a negative electrode sheet and then winding them to obtain a battery cell, placing the battery cell in an outer packaging, and injecting electrolyte into the outer packaging to obtain the battery of the present invention.

[0095] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0096] Additive A of this invention is an unsaturated cyclic compound containing sulfonic acid groups. The sulfonic acid functional groups can form alkyl sulfonate lithium RSO3Li on the negative electrode surface, which increases the ionic conductivity of the SEI film. Simultaneously, the cyclic carbonate or imidazolium ketone structures can polymerize on the negative electrode surface, participating in the formation of the SEI film. Furthermore, under high voltage, additive A can decompose into a film at the positive electrode, reducing the LiF content, improving interfacial lithium conductivity, and simultaneously inhibiting the decomposition of LiPF6 and the electrolyte on the positive electrode surface.

[0097] In the additive B (ADN and HTCN) structure of the present invention, the electron-rich nature of the -C≡N cyano N forms a strong complex with the electron-deficient Co on the LiCoO2 (LCO) surface, which can inhibit its erosion and dissolution by electrolyte or other corrosive byproducts.

[0098] The additive C (bisfluorosulfonyl imide salt) of this invention is a positive electrode protection additive that can continuously repair the positive electrode surface in the later stages of cycling.

[0099] Furthermore, the combination of additives A, B, and C in this invention satisfies the following relationship:

[0100] 0.36≤(C B +0.5C A ) / (C C -0.5C A )≤4

[0101] Among them, C A C represents the mass percentage of additive A. B C represents the mass percentage of additive B; C The value represents the mass percentage of additive C, where 1 ≤ A ≤ 4, 0.1 ≤ B ≤ 3, and 2 ≤ C ≤ 7. Within this range, the combination of additives A, B, and C provides the best protective effect and, in terms of safety, effectively achieves a barrier function. Detailed Implementation

[0102] This invention discloses an electrolyte and a battery. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0103] The reagents and materials used in this invention are all commercially available.

[0104] The present invention will be further illustrated below with reference to the embodiments:

[0105] Examples 1-10, Comparative Examples 1-8

[0106] Lithium-ion batteries are prepared through the following steps:

[0107] 1) Preparation of positive electrode sheet

[0108] Lithium cobalt oxide (LiCoO2), polyvinylidene fluoride (PVDF), super P (SP), and carbon nanotubes (CNT) were mixed in a mass ratio of 96:2:1.5:0.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred under vacuum until it formed a uniform and fluid positive electrode slurry. The positive electrode slurry was then uniformly coated onto both surfaces of an aluminum foil. The coated aluminum foil was dried, and then rolled and slit to obtain the desired positive electrode sheet.

[0109] 2) Preparation of negative electrode sheet

[0110] The negative electrode active materials, artificial graphite, silicon suboxide, sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber, conductive carbon black (SP), and single-walled carbon nanotubes (SWCNTs), were mixed in a mass ratio of 79.5:15:2.5:1.5:1:0.5, and deionized water was added. The mixture was stirred in a vacuum mixer to obtain a negative electrode active slurry. The negative electrode active slurry was uniformly coated on both surfaces of a copper foil. The coated copper foil was dried at room temperature and then transferred to an 80°C oven for drying for 10 hours. After cold pressing and slitting, the negative electrode sheet was obtained.

[0111] 3) Preparation of electrolyte

[0112] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), EC / PC / DEC / PP were mixed uniformly in a mass ratio of 10 / 20 / 10 / 60. Then, 1 mol / L of fully dried lithium hexafluorophosphate (LiPF6) was quickly added to dissolve it. After dissolving, 8 wt% of fluoroethylene carbonate and 2 wt% of 1,3-propenesulfonate lactone based on the total mass of the electrolyte were added. Additive A (as shown in structural formula 6), as well as additive B (ADN / HTCN = 1 / 1) and additive C (lithium difluorosulfonylimide) were added. The amount of each additive added is shown in Table 1.

[0113] The specific electrolyte formulations for the examples and comparative examples are as follows:

[0114] Table 1. Composition of electrolyte additives in lithium-ion batteries of the examples and comparative examples.

[0115]

[0116]

[0117] 4) Preparation of lithium-ion batteries

[0118] The positive electrode sheet from step 1), the negative electrode sheet from step 2), and the separator are stacked in the order of positive electrode sheet, separator, and negative electrode sheet, and then wound to obtain a battery cell. The battery cell is placed in an outer packaging aluminum foil, and the electrolyte from step 3) is injected into the outer packaging. After vacuum sealing, settling, formation, shaping, and sorting, a lithium-ion battery is obtained.

[0119] Lithium-ion battery performance test 1

[0120] The lithium-ion batteries prepared in the above embodiments and comparative examples were subjected to performance tests, with a charge / discharge range of 3.0-4.5V.

[0121] 1) High-temperature cycling performance test at 45℃

[0122] The battery was charged and discharged for 800 cycles at 45°C at a rate of 1C within the charge and discharge cutoff voltage range. The discharge capacity of the first cycle was measured as x1 mAh, and the discharge capacity of the Nth cycle was measured as y1 mAh. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate R1 = y1 / x1.

[0123] 2) Safety performance testing:

[0124] Charge the battery cell at 0.5C to the upper limit cutoff voltage, and then maintain the voltage at 0.05C. At an ambient temperature of 25℃±5℃, place the fully charged sample in a thermal shock test chamber, then raise the temperature to 140℃±2℃ at a rate of 15℃±2℃ / min and maintain this temperature for 42 minutes. After the test, observe whether the battery catches fire or explodes. If it neither catches fire nor explodes, the safety performance is indicated as "Safe" (OK). If it only catches fire, it is indicated as "Fire". If it only explodes, it is indicated as "Explosion". If it both catches fire and explodes, the safety performance is indicated as "Fire and Explosion" (NG).

[0125] Table 2. Performance test results of lithium-ion batteries in the examples and comparative examples.

[0126]

[0127] The examples and comparative examples show that additives A and B have a significant effect on the performance of cycling at 45°C and high-temperature storage, and a significant improvement in safety performance. Furthermore, the combination of A, B, and C satisfies the condition 0.36 ≤ (C). B +0.5C A ) / (C C -0.5C A When the value is ≤4, the improvement in safety performance is most significant.

[0128] Examples 11-21

[0129] Except for the type of additive A, the preparation of the lithium-ion battery is the same as in Example 3. The types of additive A corresponding to the examples are shown in Table 3.

[0130] Lithium-ion battery performance test 2

[0131] The lithium-ion batteries prepared in the above embodiments and comparative examples were subjected to performance tests using the same methods as before. The test results are as follows:

[0132] Table 3. Performance test results of lithium-ion batteries in Examples 11-21

[0133]

[0134] The experimental results above show that when additive A, represented by structural formulas 1-5 and 7-12, is used in combination with additives B and C, the effect on the 45℃ cycling and high-temperature storage performance is also quite significant, and the safety performance is significantly improved.

[0135] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electrolyte, characterized in that, The electrolyte includes an organic solvent, a lithium salt, additive A, additive B, and additive C; The additive A is at least one of structural formulas 1 to 12: ； Additive B is a polycyano nitrile compound; The additive C is a difluorosulfonylimide salt; The electrolyte satisfies the following relationship: 0.36≤(C B +0.5C A ) / (C C -0.5C A )≤3 Where 1≤C A ≤4, 0.1≤C B ≤3, 2≤C C ≤7, C A C represents the mass percentage of additive A in the electrolyte. B C represents the mass percentage of additive B in the electrolyte; C This represents the mass percentage of additive C in the electrolyte.

2. The electrolyte according to claim 1, characterized in that, The polycyano nitrile compounds are adiponitrile and 1,3,6-hexanetrionitrile; The difluorosulfonyl imide salt includes at least one of lithium difluorosulfonyl imide, sodium difluorosulfonyl imide, potassium difluorosulfonyl imide, rubidium difluorosulfonyl imide, and cesium difluorosulfonyl imide.

3. The electrolyte according to claim 1, characterized in that, The electrolyte further includes additive D, which includes at least one of fluoroethylene carbonate, 1,3-propenesulfonate lactone, ethylene sulfate, lithium difluorooxalate borate, lithium difluorophosphate, and lithium difluorodioxalate phosphate.

4. The electrolyte according to claim 1, characterized in that, The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorobis(oxalate) phosphate, lithium tetrafluoroborate, lithium bis(oxalate) borate, lithium hexafluoroantimonyate, lithium hexafluoroarsenate, lithium di(trifluoromethanesulfonyl)imide, lithium di(pentafluoroethylsulfonyl)imide, lithium tri(trifluoromethanesulfonyl)methyl, or lithium di(trifluoromethanesulfonyl)imide.

5. The electrolyte according to claim 1, characterized in that, The organic solvent is selected from carbonates and / or carboxylic esters.

6. The electrolyte according to claim 5, characterized in that, The carbonate is selected from one or more of the following solvents, whether fluorinated or unsubstituted: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. The carboxylic acid ester is selected from one or more of the following solvents, whether fluorinated or unsubstituted: propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, propyl propionate, ethyl propionate, methyl butyrate, and ethyl n-butyrate.

7. A battery, characterized in that, The electrolyte includes any one of claims 1-6.

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