Electrolyte containing high-voltage high-temperature additive composition and lithium ion battery

Abstract

The application discloses a kind of electrolyte of high-voltage high-temperature type additive composition, including main lithium salt, organic solvent and additive, the additive includes: first additive selected from the structure shown in formula (I-1) and / or formula (I-2), second additive selected from at least one of the structure shown in formula (II-1), (II-2) or (II-3), the structural formula of additive is seen in specification.The electrolyte provided by the application is used in high-voltage battery system, has excellent high-temperature cycle performance, high-temperature storage performance while having lower cell internal resistance, and can inhibit moisture and acidity in electrolyte.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery electrolytes, and particularly to an electrolyte and lithium-ion battery that improves the high-temperature cycle performance and high-temperature storage performance of high-voltage lithium-ion batteries while reducing the internal resistance of the cell. Background Technology

[0002] High-energy-density, high-voltage batteries represent the future trend in lithium-ion battery development. However, with increasing energy density, the electrochemical performance of the cells, especially high-temperature storage and cycling, faces significant challenges. To improve the high-temperature performance of batteries, high-temperature additives are often added, such as sulfonates like 1,3-propanesulfonyl lactone (PS) and propylene-1,3-sulfonyl lactone (PES), as well as anhydrides and nitrile compounds. However, sulfonates are sulfur-containing additives, posing environmental and thermal stability issues; anhydrides have insufficient high-temperature storage performance, exhibiting accelerated degradation in the later stages of battery cycling; while nitrile compounds offer significant advantages in high-temperature storage, their excessively thick interfacial films result in high internal resistance and incompatibility with graphite anodes.

[0003] LG's patent KR1020170110995A discloses a combined additive using unsaturated silane and lithium bis(fluorosulfonyl)imide (LiFSI). While this additive can improve cell cycle performance and high-temperature storage stability, the unsaturated silane forms a high-resistivity interfacial film on the positive and negative electrode surfaces, inducing lithium deposition. The deposited Li then reacts with the electrolyte, consuming active lithium and causing capacity loss. Furthermore, at voltages above 3.5V, LiFSI corrodes the Al current collector, making it unsuitable for high-voltage cathode materials such as ternary cathodes.

[0004] CATL's patent CN109309248A discloses a combination additive that uses phosphate ester compounds and sulfate ester / sulfonate ester compounds. Although this combination additive can suppress gas generation during high-temperature storage of batteries and improve the retention rate of remaining capacity during high-temperature storage, thereby improving high-temperature storage performance, it also faces the defect of high internal resistance.

[0005] Existing additives such as ethylene sulfate (DTD) or methylene disulfonate (MMDS) can help improve the high-temperature performance of battery cells and reduce internal resistance. However, under high-voltage systems, the electrolyte will continue to undergo oxidative decomposition reactions on the positive electrode surface, leading to deterioration of the battery's high-temperature (above 45°C) storage performance and thermal shock performance. Therefore, the improvement effect is still not ideal.

[0006] Therefore, in high-voltage battery systems, it is of great practical significance to seek a low-impedance, high-temperature additive or additive composition. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes an electrolyte containing a high-voltage, high-temperature additive composition that can significantly improve the high-temperature cycle performance and high-temperature storage performance of batteries, while also exhibiting low cell internal resistance.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] An electrolyte containing a high-voltage, high-temperature additive composition, comprising a main lithium salt and an organic solvent, wherein the electrolyte further comprises:

[0010] The first additive is selected from the structures shown in formula (I-1) and / or formula (I-2):

[0011]

[0012] R1, R2, and R3 are independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C1-C5 cyanosubstituted hydrocarbon, C2-C5 unsaturated hydrocarbon, or C2-C5 halounsaturated hydrocarbon.

[0013] The second additive is selected from at least one of the structures shown in formula (II-1), (II-2), or (II-3):

[0014]

[0015] Formula (II-1) represents a chain structure, wherein A is selected from silicon, boron, nitrogen or phosphorus, L is selected from oxygen or a straight bond, and R4, R5, R6, and R7 are independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C2-C5 unsaturated hydrocarbon, C2-C5 halounsaturated hydrocarbon or C1-C5 cyanosubstituted hydrocarbon; a, b, c, and d are 0 or 1, and at least two of them are 1, meaning that there are at least two branches connected to A; Formula (II-1) contains at least two unsaturated bonds;

[0016] Formulas (II-2) and (II-3) represent multi-component heterocycles, where X1 is boron or nitrogen, Q is selected from carbonyl or oxygen; n represents the number of repeating units on the multi-component heterocycle, n is selected from 2 to 6; R8 is selected from C2-C5 unsaturated hydrocarbon groups, C2-C5 halounsaturated hydrocarbon groups, or C1-C5 cyano-substituted hydrocarbon groups; R9, R 10 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C2-C5 unsaturated hydrocarbon, C2-C5 halounsaturated hydrocarbon, or C1-C5 cyano-substituted hydrocarbon, and R9, R 10 At least one of them contains an unsaturated bond. R8, R9, R 10 The unsaturated bonds are any one of carbon-carbon double bonds, carbon-carbon triple bonds, or carbon-nitrogen triple bonds.

[0017] Preferably, R1, R2, and R3 are independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 cyanosubstituted hydrocarbon, C2-C3 unsaturated hydrocarbon, or C2-C3 halounsaturated hydrocarbon.

[0018] In formula (II-1), R4, R5, R6, and R7 are independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C2-C3 unsaturated hydrocarbon, C2-C3 halounsaturated hydrocarbon, or C1-C3 cyanosubstituted hydrocarbon; at least three of a, b, c, and d are 1;

[0019] In formulas (II-2) and (II-3), n is selected from 3 to 5; R8 is selected from C2-C3 unsaturated hydrocarbon groups, C2-C3 halogenated unsaturated hydrocarbon groups, or C1-C3 cyano-substituted hydrocarbon groups; R9, R 10 It is independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C2-C3 unsaturated hydrocarbon, C2-C3 halounsaturated hydrocarbon or C1-C3 cyanosubstituted hydrocarbon.

[0020] More preferably, R1, R2, and R3 are independently selected from methyl, ethyl, cyano, methylene cyano, monofluoromethyl, trifluoroethyl, and allyl.

[0021] In formula (II-1), R4, R5, R6, and R7 are independently selected from vinyl, propylene, perfluorovinyl, and methylene cyano.

[0022] In formulas (II-2) and (II-3), R8 is selected from vinyl and propylene groups; R9, R 10 Selected independently from methyl and vinyl.

[0023] Most preferably, in the electrolyte containing the high-voltage, high-temperature additive composition of the present invention, the first additive is selected from at least one of the following structures:

[0024]

[0025] The second additive is selected from at least one of the following structures:

[0026]

[0027] In the electrolyte containing the high-voltage, high-temperature additive composition, the amount of the first additive in the electrolyte is 0.1% to 5.0%, and the amount of the second additive in the electrolyte is 0.1% to 5.0%. Preferably, the amount of the first additive in the electrolyte is 0.2% to 2%, and the amount of the second additive in the electrolyte is 0.2% to 3%.

[0028] When the first additive and the second additive of this invention are used in combination, the first additive can be oxidized in advance on the positive electrode surface to form a dense CEI film; the second additive can form films on both the positive and negative electrode surfaces simultaneously, further hindering the continuous decomposition of the electrolyte on the electrode surface. Since the mechanism of action is not yet clear, the inventors speculate through research that the PF bonds in the first additive are unstable and easily detached. - The strong electron-withdrawing ability of the first additive forms active sites on the surfaces of the positive and negative electrode materials, which helps the second additive to form a better film, thereby significantly reducing the internal resistance of the battery and further suppressing gas generation in the cell, improving the high-temperature cycling and high-temperature storage performance of the cell. At the same time, the first additive also has the function of removing acid and water. Koeun Kim et al. believe that reducing the water and acidity content in the electrolyte helps to inhibit the decomposition of LiPF6, reduce the consumption of active lithium and the deterioration of the SEI film, and reduce the internal resistance of the battery.

[0029] In the electrolyte containing the high-voltage, high-temperature additive composition of the present invention, the main lithium salt can be a commonly used lithium salt in electrolytes. Preferably, the main lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium difluorodi(oxalate)phosphate, lithium tetrafluorooxalate phosphate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide, and the concentration of the main lithium salt in the electrolyte is 0.3–3 M. More preferably, the lithium salt includes lithium hexafluorophosphate, and its concentration in the electrolyte is 0.5–2 M.

[0030] In the electrolyte containing the high-voltage, high-temperature additive composition of the present invention, the organic solvent can be a commonly used organic solvent in electrolytes. Preferably, the organic solvent is selected from at least one of C3-C6 carbonate or fluorocarbonate compounds, C3-C8 carboxylic acid esters or fluorocarboxylic acid ester compounds, sulfone compounds, and ether compounds.

[0031] More preferably, the C3 to C6 carbonate or fluorocarbonate compound is selected from at least one of ethylene carbonate, propylene carbonate, butene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoroethylene carbonate, and difluoroethylene carbonate.

[0032] The C3-C8 carboxylic acid esters or fluorocarboxylic acid esters are selected from at least one of γ-butyrolactone, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl acetate, propyl propionate, and ethyl fluoroacetate.

[0033] The sulfone compound is selected from at least one of sulfolane, dimethyl sulfoxide, dimethyl sulfone, and diethyl sulfone;

[0034] The ether compound is selected from at least one of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0035] The electrolyte containing the high-voltage, high-temperature additive composition of the present invention further comprises a basic additive, wherein the basic additive is selected from at least one of acid anhydride compounds, sulfonate compounds, sulfate compounds, trimethylsilyl ester compounds, unsaturated cyclic carbonate compounds or fluorinated cyclic carbonate compounds, and the amount of the basic additive is 0.1 to 10% of the total mass of the electrolyte.

[0036] Wherein, the acid anhydride compound is selected from at least one of succinic anhydride, maleic anhydride, and citrate anhydride; the sulfonate compound is selected from at least one of 1,3-propanesulfonyl lactone, 1,4-butanesulfonate lactone, methanedisulfonate, and 1,3-propenesulfonate lactone; the sulfate compound is selected from at least one of vinyl sulfate, trimethylene cyclic sulfate, methyl vinyl sulfate, and 4,4'-divinyl sulfate; the trimethylsilyl ester compound is selected from at least one of tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, and tris(trimethylsilyl)trifluoromethanesulfonate; the unsaturated cyclic carbonate compound is selected from vinylene carbonate and / or vinyl ethylene carbonate; and the fluorinated cyclic carbonate compound is selected from at least one of fluoroethylene carbonate, difluoroethylene carbonate, or trifluoromethyl ethylene carbonate.

[0037] The present invention also provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte containing a high-voltage, high-temperature additive composition as described above.

[0038] The active material of the positive electrode is selected from nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium cobalt oxide materials, or lithium iron phosphate materials.

[0039] The active material of the negative electrode is selected from graphite, silicon carbide, silicon suboxide, silicon, tin, lithium metal or composite materials thereof.

[0040] The lithium-ion battery described in this invention has a charging cutoff voltage higher than 4.2V. The electrolyte described in this invention is particularly suitable for high-voltage, high-temperature battery systems.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. When the electrolyte of the present invention is used in a high-voltage battery system, it can improve the high-temperature cycle performance and high-temperature storage performance of the battery, and has a low cell internal resistance.

[0043] 2. The electrolyte of the present invention can suppress moisture and acidity in the electrolyte, further reduce battery resistance, and improve battery performance. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0045] I. Preparation of Electrolyte

[0046] Preparation of basic electrolyte: In an argon-filled glove box (moisture < 5 ppm, oxygen < 10 ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were uniformly mixed at a mass ratio of EC:EMC:DEC = 3:5:2. Lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solution until the molar concentration of LiPF6 was 1.0 mol / L, thus obtaining the basic electrolyte.

[0047] Example 1: 1.0 wt% of compound A1 and 5.0 wt% of compound B1 were added to the basic electrolyte to obtain the electrolyte of this example.

[0048] Example 2: 0.5 wt% of compound A3 and 2.0 wt% of compound B2 were added to the basic electrolyte to obtain the electrolyte of this example.

[0049] Example 3: 2.0 wt% of compound A5 and 1.0 wt% of compound B3 were added to the basic electrolyte to obtain the electrolyte of this example.

[0050] Example 4: 5.0 wt% of compound A7 and 0.2 wt% of compound B4 were added to the base electrolyte to obtain the electrolyte of this example.

[0051] Example 5: 1.0 wt% of compound A2 and 0.5 wt% of compound B5 were added to the basic electrolyte to obtain the electrolyte of this example.

[0052] Example 6: 0.2 wt% of compound A4 and 0.2 wt% of compound B6 were added to the base electrolyte to obtain the electrolyte of this example.

[0053] Example 7: 2.0 wt% of compound A6 and 2.0 wt% of compound B7 were added to the base electrolyte to obtain the electrolyte of this example.

[0054] Example 8: 5.0 wt% of compound A1 and 0.5 wt% of compound B8 were added to the base electrolyte to obtain the electrolyte of this example.

[0055] Example 9: 0.5 wt% of compound A1 and 0.2 wt% of compound B3 were added to the base electrolyte to obtain the electrolyte of this example.

[0056] Example 10: 0.5 wt% of compound A1 and 0.2 wt% of compound B6 were added to the base electrolyte to obtain the electrolyte of this example.

[0057] Example 11: 0.5 wt% of compound A1 and 0.2 wt% of compound B9 were added to the base electrolyte to obtain the electrolyte of this example.

[0058] Example 12: 0.5 wt% of compound A3 and 0.2 wt% of compound B3 were added to the basic electrolyte to obtain the electrolyte of this example.

[0059] Example 13: 0.5 wt% of compound A7 and 0.2 wt% of compound B3 were added to the base electrolyte to obtain the electrolyte of this example.

[0060] Comparative Example 1: 0.5 wt% of compound A1 was added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0061] Comparative Example 2: 1.0 wt% of compound A2 was added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0062] Comparative Example 3: 0.2 wt% of compound B3 was added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0063] Comparative Example 4: 0.5 wt% of compound B5 was added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0064] Comparative Example 5: 0.5 wt% of compound A1 and 0.2 wt% adiponitrile (ADN) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0065] Comparative Example 6: 0.5 wt% of compound A3 and 0.2 wt% of 1,3-propanesulfonyl lactone (PS) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0066] Comparative Example 7: 0.5 wt% of the compound methane disulfonate methylene ester (MMDS) and 0.2 wt% B3 were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0067] Comparative Example 8: To the basic electrolyte, 0.5 wt% of the compound vinyl sulfate (DTD) and 0.2 wt% B6 were added to obtain the electrolyte of this comparative example.

[0068] Comparative Example 9: 0.5 wt% of compound A1 and 0.2 wt% of vinylene carbonate (VC) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0069] Comparative Example 10: 0.2 wt% of compound B3 and 0.5 wt% of vinylene carbonate (VC) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0070] II. Battery Manufacturing and Performance Testing

[0071] The lithium-ion battery electrolytes from the above embodiments and comparative examples were used to fabricate 1000mAh capacity soft-pack lithium-ion power batteries. Each lithium-ion power battery includes a positive electrode, a negative electrode, a separator, an electrolyte, and battery auxiliary materials. The positive electrode active material is LiNi. 0.83 Co 0.07 Mn 0.2 O2, with graphite as the negative electrode active material.

[0072] The preparation process is as follows: the positive electrode, separator and negative electrode are wound together into a core, sealed with aluminum-plastic film and then baked to ensure that the electrode moisture meets the requirements. After baking, the cell is injected with electrolyte and then subjected to standing, formation, capacity testing and aging processes to obtain the finished soft-pack cell.

[0073] The performance of the aforementioned lithium-ion batteries was tested, including:

[0074] 1. High-temperature cycling performance test

[0075] Charge the battery at a constant current of 1C at 45℃ until the charging cutoff voltage, then charge at a constant voltage until the current drops to 0.1C, and then discharge at a constant current of 1C until 2.8V. Repeat this cycle for a specific number of cycles, recording the discharge capacity of the first cycle and the discharge capacity of the last cycle. Calculate the battery's capacity retention rate using the following formula:

[0076] Capacity retention rate = discharge capacity in the last week / discharge capacity in the first week * 100%.

[0077] 2. High-temperature storage performance test

[0078] Cycle the battery at room temperature for one week according to the cycle performance test method, recording the discharge capacity, internal resistance, and volume in the first week. Then, charge it at a constant current of 1C until the charging cutoff voltage, and then charge it at a constant voltage until the current drops to 0.1C. Let it stand in a 60℃ constant temperature oven for 28 days. Then, cycle it at room temperature for two weeks according to the cycle performance test method, recording the discharge capacity in the first week after high-temperature standing, the discharge capacity in the second week, and the internal resistance and volume after storage. Calculate the capacity retention rate, internal resistance growth rate, and volume expansion rate after battery storage using the following formula:

[0079] Capacity retention rate = Discharge capacity in the first week after high temperature settling / Discharge capacity in the first week * 100%.

[0080] Internal resistance growth rate = (internal resistance after storage - internal resistance in week 1) / internal resistance in week 1 * 100%.

[0081] Volume expansion rate = (volume after storage - volume in week 1) / volume in week 1 * 100%.

[0082] 3. Cell internal resistance

[0083] The cell's state of charge (SOC) was adjusted to 50% using a 0.2C constant current charging method, and then left to rest for 30 minutes. The open-circuit voltage (OCV1) at the end of the rest period was measured. Then, the cell was discharged for 10 seconds at the maximum pulse current (3C) specified by the battery manufacturer, and the voltage (OCV2) at the moment the high-current discharge terminated was collected. The battery's DCIR was calculated using the following formula:

[0084] DCIR = (OCV1 - OCV2) / 3C

[0085] 4. Moisture and acidity

[0086] Moisture and acidity tests were conducted on the electrolyte before and after storage at 50℃ for 24 hours, in accordance with SJ / T11723-2018. The free acid content was expressed as HF and calculated using the following formula:

[0087] C HF =C*V*M HF *1000 / m

[0088] In the formula:

[0089] C HF Free acid content (as HF), mg / kg;

[0090] C represents the concentration of the sodium methoxide standard titration solution, in mol / L;

[0091] V is the volume of sodium methoxide standard titration solution consumed in the titration, in mL;

[0092] M is the sample mass, in grams;

[0093] M HFThe molar mass of hydrofluoric acid is (20.006), in g / mol.

[0094] The arithmetic mean of the two test values ​​is taken as the test result.

[0095] The specific test results are shown in Tables 1 and 2 below:

[0096] Table 1 Electrochemical test results of NCM622-4.3V

[0097]

[0098] Comparing the test results of Examples 1-8 and Comparative Examples 1-4, it can be seen that the combined use of the first and second additives of the present invention improves the high-temperature cycling performance of the battery cell compared with the use of the first additive alone. Compared with the use of the second additive alone, it overcomes the disadvantage of high internal resistance. More importantly, the combined use further improves the high-temperature cycling capacity retention rate of the electrolyte, significantly reduces gas production during 28 days of high-temperature storage of the battery cell, and slows down the increase in internal resistance, thus improving the high-temperature storage performance of the battery cell.

[0099] Comparing the test results of Examples 9-13 and Comparative Examples 5-10, it can be seen that the combined use of the first and second additives of the present invention exhibits a higher high-temperature cycle capacity retention rate and a smaller volume expansion rate after storage compared to the first additive used with other high-temperature additives. The internal resistance of the combined use of the first and second additives of the present invention is lower than that of the second additive used with other lower internal resistance additives. Therefore, the combined use of the first and second additives of the present invention, under high-voltage systems, not only significantly improves the high-temperature storage and cycling performance of the battery cell but also exhibits lower internal resistance.

[0100] Table 2. Results of moisture and acidity tests on the electrolyte after storage at 45℃ for 24 hours.

[0101]

[0102] As shown in Table 2, the first type of additive has the function of removing acid and water, which can inhibit the increase of moisture and acidity after electrolyte storage and improve the thermal stability of electrolyte.

Claims

1. An electrolyte solution containing a high-voltage high-temperature additive composition, comprising a main lithium salt, an organic solvent, characterized in that: The electrolyte further comprises: a first additive selected from at least one of the following structures: a second additive selected from at least one of the following structures:

2. The electrolyte containing high-voltage high-temperature additive composition according to claim 1, characterized by: The first additive is added in an amount of 0.1-5.0% in the electrolyte, and the second additive is added in an amount of 0.1%-5.0% in the electrolyte.

3. The electrolyte containing high-voltage high-temperature additive composition according to claim 1, characterized by that: The main lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorodioxalate phosphate, lithium tetrafluorodioxalate phosphate, lithium bisfluorosulfonimide, lithium bis(trifluoromethylsulfonyl)imide, and the concentration of the main lithium salt in the electrolyte is 0.5-3M; The organic solvent is selected from at least one of C3-C6 carbonate or fluorinated carbonate compounds, C3-C8 carboxylic acid ester or fluorinated carboxylic acid ester compounds, sulfone compounds, and ether compounds.

4. The electrolyte containing the high-voltage high-temperature additive composition according to claim 3, characterized in that: The C3-C6 carbonate or fluorinated carbonate compound is selected from at least one of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluorinated vinyl carbonate, and difluorinated vinyl carbonate; The C3-C8 carboxylic acid ester or fluorinated carboxylic acid ester compound is selected from at least one of γ-butyrolactone, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl acetate, propyl propionate, and fluorinated ethyl acetate; The sulfone compound is selected from at least one of sulfolane, dimethyl sulfoxide, dimethyl sulfone, and diethyl sulfone; The ether compound is selected from at least one of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

5. The electrolyte containing high-voltage high-temperature additive composition according to any one of claims 1 to 4, characterized in that: The electrolyte further comprises a base additive selected from at least one of anhydride compounds, sulfonic acid ester compounds, sulfuric acid ester compounds, trimethylsilyl ester compounds, unsaturated cyclic carbonate compounds, or fluorinated cyclic carbonate compounds, and the amount of the base additive is 0.1-20% of the total mass of the electrolyte.

6. The electrolyte containing the high-voltage high-temperature additive composition according to claim 5, characterized in that: The anhydride compound is selected from at least one of succinic anhydride, maleic anhydride, and citraconic anhydride; The sulfonic acid ester compound is selected from at least one of 1,3-propane sulfonic lactone, 1,4-butane sulfonic lactone, methane disulfonic acid methylene ester, and 1,3-propylene sulfonic lactone; The sulfuric acid ester compound is selected from at least one of vinyl sulfate, trimethylene cyclic sulfuric acid ester, methyl vinyl sulfate, and 4,4'-vinylene sulfite; The trimethylsilyl ester compound is selected from at least one of tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, and tris(trimethylsilyl)trifluoromethanesulfonate; The unsaturated cyclic carbonate compound is selected from the group consisting of vinylene carbonate and / or vinyl ethylene carbonate; the fluorinated cyclic carbonate compound is selected from the group consisting of at least one of vinyl fluoride carbonate, difluorinated vinyl carbonate or trifluoromethyl vinyl carbonate.

7. A lithium-ion battery comprising a positive electrode, a negative electrode, a separator, characterized in that: The lithium ion battery further comprises the electrolyte of the lithium ion battery according to any one of claims 1-6.

8. The lithium-ion battery of claim 7, wherein: The charging cut-off voltage of the lithium ion battery is higher than 4.2V.

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