Lithium ion battery electrolyte and lithium ion battery

Abstract

The application discloses a lithium ion battery electrolyte and a lithium ion battery containing the electrolyte. The electrolyte comprises a main lithium salt, an organic solvent, and a first additive and a second additive. The first additive is lithium difluorophosphate trifluoroborate represented by the following formula (A): wherein x+y=4, x>=0, y>=1, and x and y are positive integers. The second additive is a sulfonate compound or a sulfate compound. The electrolyte can effectively improve the high-temperature storage and high-temperature cycle performance of the battery under high voltage and high temperature, and meanwhile, the battery has good low-temperature and rate characteristics.

Description

Technical Field

[0001] This invention relates to the field of battery electrolytes, particularly lithium-ion battery electrolytes, and especially to a lithium-ion battery electrolyte containing lithium trifluoroborate difluorophosphate electrolyte additive. Background Technology

[0002] High energy density is the development trend of lithium batteries. Common methods to improve it include increasing the operating voltage or increasing the nickel content in the cathode material. However, both of these methods pose new challenges to the cycle performance and safety performance of the cell. Therefore, for high-nickel, high-voltage lithium batteries, it is particularly important to construct a more robust positive and negative electrode interface and improve the battery's high-temperature performance and cycle performance.

[0003] Sulfonate compounds (such as PS, PST, and their derivatives) can form films at both positive and negative electrodes, creating interfacial films rich in sulfonate components. These films can effectively inhibit redox reactions in the solvent on the electrode surfaces, thereby improving gas generation and capacity recovery during high-temperature storage. However, most sulfonate compounds have high film-forming resistance, resulting in insufficient low-temperature and rate performance. Furthermore, during cycling, the continuous modification of the interfacial film leads to rapid increases in DCR resistance, resulting in active lithium loss and a rapid decline in cycle life.

[0004] To address the issues of high film-forming resistance, low-temperature rate capability, and insufficient cycle performance of sulfonate compounds, existing technologies often employ them in combination with carbonate additives, sulfate additives, etc., to improve the film-forming performance of the negative electrode. However, these technologies still cannot solve the problem of continuous DCR growth during high-pressure and high-temperature storage and cycling, which leads to insufficient cycle life.

[0005] Sulfate compounds, such as vinyl sulfate (DTD) and its derivatives, can form an effective interfacial film at the negative electrode with relatively low film-forming impedance, thus improving cycle performance and high-temperature storage capacity recovery. However, because sulfate compounds have a weak film-forming effect at the positive electrode interface, they cannot effectively suppress gas generation during storage, especially at high voltages. Their protective effect on the positive electrode interfacial film is insufficient, and they cannot effectively suppress side reactions at the positive electrode electrolyte interface. Therefore, their improvement on battery performance is limited, resulting in weak storage and cycle performance at high temperatures and voltages.

[0006] Existing technologies often employ cathode film-forming additives to form an effective protective film on the cathode surface, suppressing side reactions at the electrolyte-cathode interface and improving interface stability, thereby enhancing storage and cycle stability under high temperatures and high voltages. However, most cathode film-forming additives, such as 1,3-propanesulfonyl lactone (PS) and 1,3-propenesulfonyl lactone (PST), exhibit high impedance, and the interfacial impedance continues to increase during storage and cycling, severely impacting the battery's low-temperature and power characteristics as well as long-term cycle stability.

[0007] Therefore, there is a need to find a new type of electrolyte additive or electrolyte additive composition that can improve low-temperature and rate performance while enhancing the high-temperature storage and high-temperature cycling performance of batteries under high voltage and high temperature conditions, and suppress impedance growth during storage and cycling to improve the cycle life of the battery cell. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a lithium-ion battery electrolyte and a lithium-ion battery that improves the storage and cycle performance of batteries under high voltage and high temperature conditions, while ensuring good low-temperature and rate performance.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A lithium-ion battery electrolyte, comprising: a main lithium salt, an organic solvent, and:

[0011] The first additive is selected from lithium trifluoroborate difluorophosphate as shown in formula (A):

[0012]

[0013] In the formula, x + y = 4, x ≥ 0, y ≥ 1, and x and y are positive integers;

[0014] The second additive is a sulfonate compound or a sulfate compound, wherein the sulfonate compound includes: a chain sulfonate compound of formula (B-1) and / or a cyclic sulfonate compound of formula (B-2); and the sulfate compound includes: a chain sulfate compound of formula (C-1) and / or a cyclic sulfate compound of formula (C-2).

[0015]

[0016] in:

[0017] R1, R2, R4, and R5 are independently selected from at least one of C1-C6 alkyl, C1-C6 haloalkyl, C2-C6 alkenyl, C2-C6 haloalkenyl, C2-C6 alkynyl, or C2-C6 haloalkynyl.

[0018] R3 and R6 are independently selected from at least one of C1-C6 alkylene, C1-C6 haloalkylene, C2-C6 alkenyl or C2-C6 haloalkenyl.

[0019] Furthermore, R1, R2, R4, and R5 are independently selected from at least one of C1-C3 alkyl, C1-C3 haloalkyl, C2-C3 alkenyl, C2-C3 haloalkenyl, C2-C3 alkynyl, or C2-C3 haloalkynyl.

[0020] R3 and R6 are independently selected from at least one of C1-C3 alkylene, C1-C3 haloalkylene, C2-C3 alkenyl or C2-C3 haloalkenyl.

[0021] More preferably, the first additive is selected from at least one of the following structures:

[0022]

[0023] The second additive is selected from at least one of the following structures:

[0024]

[0025] In the electrolyte of the present invention, the amount of the first additive is 0.1 to 10.0% of the total mass of the electrolyte, and the amount of the second additive is 0.05 to 5.0% of the total mass of the electrolyte. Preferably, the amount of the first additive is 0.1 to 2.0% of the total mass of the electrolyte, and the amount of the second additive is 0.1 to 2.0% of the total mass of the electrolyte.

[0026] To improve the overall performance of the battery, the electrolyte further includes a third additive, which is selected from at least one of carbonate additives and their derivatives, and fluorinated lithium salt additives, and is used in an amount of 0.01 to 5.0% of the total mass of the electrolyte. Preferably, the third additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalate)difluorophosphate, lithium difluorooxalateborate, or lithium tetrafluoroborate, and is used in an amount of 0.1 to 5.0% of the total mass of the electrolyte, and the third additive is different from the main lithium salt.

[0027] The main lithium salt can be any commonly used lithium salt in electrolytes. Preferably, the main lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, or lithium bis(trifluoromethanesulfonyl)imide, and its molar concentration in the electrolyte is 0.4–1.6 mol / L; more preferably, the main lithium salt is lithium hexafluorophosphate, and its molar concentration in the electrolyte is 0.6–1.2 mol / L.

[0028] The organic solvent used in this invention can be any non-aqueous solvent commonly used in electrolytes. Preferably, the organic solvent is selected from at least one of C3-C6 carbonate compounds, C3-C8 carboxylic acid ester compounds, sulfone compounds, and ether compounds.

[0029] Further, the C3-C6 carbonate 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, or difluoroethylene carbonate.

[0030] The C3-C8 carboxylic acid ester compounds 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, ethyl fluoroacetate, and (2,2-difluoroethyl) acetate.

[0031] The sulfone compound is selected from at least one of sulfolane, dimethyl sulfoxide, dimethyl sulfone, or diethyl sulfone;

[0032] The ether compound is selected from at least one of triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0033] The present invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and any of the lithium-ion battery electrolytes described above.

[0034] 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; wherein, the nickel-cobalt-manganese ternary material is Li(Ni) x Co y Mn z O2, x≥0.5, y>0, z>0, x+y+z=1; the nickel-cobalt-aluminum ternary material is Li(Ni x Co y Al z) O2, x≥0.8, y>0, z>0, x+y+z=1.

[0035] The active material of the negative electrode is graphite, silicon carbide, silicon suboxide, silicon, tin, metallic lithium, or a composite material thereof.

[0036] Compared with the prior art, the beneficial effects of the present invention include:

[0037] The first additive of the present invention is a novel lithium salt additive, which can form films on the positive and negative electrodes with low film-forming impedance, has a modifying effect on the interface film, improves the stability of the positive and negative electrode interface, and can effectively suppress gas generation in the battery cell during high-temperature and high-voltage storage and cycling.

[0038] When the second additive is a sulfonate compound, the synergistic effect of the first additive and the sulfonate compound can overcome the problems of rapid DCR growth and insufficient high-temperature storage and high-temperature cycling performance of the sulfonate compound during high-temperature storage and high-temperature cycling. This effectively improves the storage performance and cycle performance of the battery under high voltage and high temperature, increases the cycle life of the cell, and ensures that the battery has good low-temperature and rate characteristics.

[0039] When the second additive is a sulfate ester compound, the synergistic effect of the first additive and the sulfate ester compound can overcome the problems of insufficient positive electrode protection and severe gas generation under high temperature and high pressure that exist in sulfonate ester compounds, effectively improving the storage performance and cycle performance of the battery under high voltage and high temperature, and ensuring that the battery has good low temperature and rate characteristics. Detailed Implementation

[0040] 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.

[0041] I. Preparation of Electrolyte

[0042] Preparation of the 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 reached 1.2 mol / L, thus obtaining the basic electrolyte.

[0043] Example 1: The electrolyte of this example is obtained by adding 0.5% by mass of first additive A1 and 1.0% by mass of second additive B1 to the base electrolyte.

[0044] Example 2: Adding 1.0% by mass of first additive A1 and 1.0% by mass of second additive B1 to the base electrolyte yields the electrolyte of this example.

[0045] Example 3: Add 1.0% by mass of first additive A1 and 2.0% by mass of second additive B1 to the base electrolyte to obtain the electrolyte of this example.

[0046] Example 4: To the base electrolyte, 1.0% by mass of first additive A1, 1.0% by mass of second additive B1, and 1.0% by mass of vinylene carbonate (VC) were added to obtain the electrolyte of this example.

[0047] Example 5: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A2, 1.0% by mass of second additive B1, and 1.0% by mass of vinylene carbonate (VC) to the base electrolyte.

[0048] Example 6: Add 1.0% by mass of first additive A2 and 1.0% by mass of second additive B4 to the base electrolyte to obtain the electrolyte of this example.

[0049] Example 7: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A2, 1.0% by mass of second additive B4 and 1.0% by mass of fluoroethylene carbonate (FEC) to the basic electrolyte.

[0050] Example 8: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A2, 1.0% by mass of second additive B5, and 1.0% by mass of lithium bis(oxalato)difluorophosphate (LiDFOP) to the base electrolyte.

[0051] Example 9: To the base electrolyte, 0.5% by mass of first additive A1 and 0.5% by mass of first additive A2, 1.0% by mass of second additive B1 and 1.0% by mass of vinylene carbonate (VC) were added to obtain the electrolyte of this example.

[0052] Example 10: The electrolyte of this example was obtained by adding 0.5% by mass of first additive A1 and 0.5% by mass of first additive A2, 1.0% by mass of second additive B4 and 1.0% by mass of fluoroethylene carbonate (FEC) to the basic electrolyte.

[0053] Example 11: The electrolyte of this example was obtained by adding 0.5% by mass of first additive A1 and 0.5% by mass of first additive A2, 1.0% by mass of second additive B5 and 1.0% by mass of lithium bis(oxalato)difluorophosphate (LiDFOP) to the base electrolyte.

[0054] Example 12: Adding 0.5% by mass of the first additive A1 and 1.0% by mass of the second additive C2 to the basic electrolyte yields the electrolyte of this example.

[0055] Example 13: Adding 1.0% by mass of the first additive A1 and 1.0% by mass of the second additive C2 to the base electrolyte yields the electrolyte of this example.

[0056] Example 14: Adding 1.0% by mass of first additive A1 and 2.0% by mass of second additive C2 to the base electrolyte yields the electrolyte of this example.

[0057] Example 15: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A1, 1.0% by mass of second additive C2, and 1.0% by mass of vinylene carbonate (VC) to the basic electrolyte.

[0058] Example 16: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A2, 1.0% by mass of second additive C2, and 1.0% by mass of vinylene carbonate (VC) to the basic electrolyte.

[0059] Example 17: Adding 1.0% by mass of first additive A2 and 1.0% by mass of second additive C4 to the base electrolyte yields the electrolyte of this example.

[0060] Example 18: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A2, 1.0% by mass of second additive C4 and 1.0% by mass of fluoroethylene carbonate (FEC) to the basic electrolyte.

[0061] Example 19: The electrolyte of this example was obtained by adding 1.0% by mass of first additive A2, 1.0% by mass of second additive C5, and 1.0% by mass of lithium bis(oxalato)difluorophosphate (LiDFOP) to the base electrolyte.

[0062] Example 20: The electrolyte of this example was obtained by adding 0.5% by mass of first additive A1 and 0.5% by mass of first additive A2, 1.0% by mass of second additive C2 and 1.0% by mass of vinylene carbonate (VC) to the base electrolyte.

[0063] Example 21: The electrolyte of this example was obtained by adding 0.5% by mass of first additive A1 and 0.5% by mass of first additive A2, 1.0% by mass of second additive C4 and 1.0% by mass of fluoroethylene carbonate (FEC) to the basic electrolyte.

[0064] Example 22: The electrolyte of this example was obtained by adding 0.5% by mass of first additive A1 and 0.5% by mass of first additive A2, 1.0% by mass of second additive C5 and 1.0% by mass of lithium bis(oxalato)difluorophosphate (LiDFOP) to the base electrolyte.

[0065] Comparative Example 1: This comparative example is consistent with the basic electrolyte.

[0066] Comparative Example 2: To the basic electrolyte, only 1.0% by mass of the third additive, fluoroethylene carbonate (FEC), was added to obtain the electrolyte of this comparative example.

[0067] Comparative Example 3: The electrolyte of this comparative example was obtained by adding only 1.0% by mass of the second additive B4 to the base electrolyte.

[0068] Comparative Example 4: The electrolyte of this comparative example was obtained by adding only 1.0% by mass of the first additive A2 to the base electrolyte.

[0069] Comparative Example 5: 1.0% by mass of the second additive B4 and 1.0% by mass of the third additive fluoroethylene carbonate (FEC) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0070] Comparative Example 6: 1.0% by mass of the first additive A2 and 1.0% by mass of the third additive fluoroethylene carbonate (FEC) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0071] Comparative Example 7: The electrolyte of this comparative example was obtained by adding only 1.0% by mass of the second additive C4 to the base electrolyte.

[0072] Comparative Example 8: 1.0% by mass of the second additive C4 and 1.0% by mass of the third additive fluoroethylene carbonate (FEC) were added to the basic electrolyte to obtain the electrolyte of this comparative example.

[0073] II. Performance Testing

[0074] The lithium-ion battery electrolytes of the above embodiments and comparative examples were used to fabricate 1500mAh 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 a nickel-cobalt-manganese ternary material, a nickel-cobalt-aluminum ternary material, a lithium cobalt oxide material, or a lithium iron phosphate material; wherein the positive electrode active material is a high-nickel ternary positive electrode LiNi. 0.83 Co 0.07 Mn 0.2 O2, the negative electrode active material is high-capacity graphite. The preparation process is as follows: the positive electrode sheet, separator and negative electrode sheet 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 after standing, formation, capacity testing and aging processes, the finished soft-pack cell is obtained.

[0075] The prepared lithium-ion power battery (soft-pack cell) was subjected to performance testing. The specific test items and methods are as follows:

[0076] (1) Battery discharge DCR test: Adjust the cell SOC to 50% with a constant current of 0.2C, let it rest for 30 minutes, and test the open circuit voltage OCV1 after the resting period; discharge for 10 seconds according to the maximum pulse current (3I1(A)) specified by the battery manufacturer, and collect the voltage OCV2 at the moment of termination of the high current discharge; calculate DCR according to the formula DCIR=(OCV1-OCV2) / 3C.

[0077] (2) 60℃ high temperature storage test: Charge the battery to 100% SOC and store it in an oven at 60±2℃ for 28 days. Test the volume before and after storage to obtain the volume expansion rate of the single cell before and after storage at 60℃. At room temperature, discharge the single cell at a current of 0.5C to the termination voltage. Repeat twice, and use the capacity of the second discharge as the recovery capacity after storage. Calculate the percentage value of the capacity relative to the initial capacity and record it as the capacity recovery rate.

[0078] (3) 45℃ high temperature cycling test: The battery is cycled in an oven at 45±1℃ with a charge / discharge current of 1C / 1C. The discharge capacity is calculated every week. The cycle is stopped after 500 cycles, and the DCR value is tested after the cycle. The capacity retention rate and DCR growth rate are calculated after the cycle.

[0079] The test results are shown in Table 1 below:

[0080] Table 1 Battery performance test results

[0081]

[0082]

[0083] By comparing Example 6 with Comparative Examples 3 and 4 in Table 1 above, it can be found that using the first additive in combination with the second additive significantly improves the high-temperature storage capacity recovery rate, gas production rate, and long-term stability during high-temperature cycling compared to using either the first additive or the second additive alone. By comparing Examples 2 and 4, and Examples 6 and 7, it was found that adding a third additive to the combination of the first and second additives further enhances the stability during high-temperature storage and high-temperature cycling.

[0084] By comparing Example 17 with Comparative Examples 4 and 7 in Table 1 above, it can be found that using the first and second additives in combination effectively improves the high-temperature storage volume expansion rate, capacity recovery rate, and high-temperature cycling stability compared to using either the first or second additive alone. Comparing Examples 13 and 15, and Examples 17 and 18, it is found that adding a third additive to the combination of the first and second additives further enhances high-temperature storage and high-temperature cycling stability without affecting the initial impedance, thus ensuring low-temperature and power characteristics.

[0085] Overall, compared to using the first, second, or third additive alone, or combinations of the three additives in pairs, the combined use of the three additives has the best effect. The combined use of the three additives can effectively suppress the negative effects of the inferior functions while giving full play to their respective advantages, achieve synergistic effects among the additives, and effectively improve the overall performance of the battery.

Claims

1. A lithium-ion battery electrolyte, comprising: A main lithium salt, an organic solvent, characterized in that the electrolyte further comprises: A first additive, the first additive is selected from lithium difluorophosphate trifluoroborate represented by the following formula (A): In the formula, x+y=4, x≥0, y≥1, and x, y are positive integers; A second additive, the second additive is a sulfonate compound or a sulfate compound, the sulfonate compound includes a chain sulfonate compound represented by the following formula (B-1) and / or a cyclic sulfonate compound represented by the following formula (B-2); the sulfate compound includes a chain sulfate compound represented by the following formula (C-1) and / or a cyclic sulfate compound represented by the following formula (C-2); Wherein: R1, R2, R4, R5 are independently selected from at least one of C1-C6 alkyl, C1-C6 haloalkyl, C2-C6 alkenyl, C2-C6 haloalkenyl, C2-C6 alkynyl or C2-C6 haloalkynyl; R3, R6 are independently selected from at least one of C1-C6 alkylene, C1-C6 haloalkylene, C2-C6 alkenylene or C2-C6 haloalkenylene.

2. The lithium ion battery electrolyte according to claim 1, characterized in that: R1, R2, R4, R5 are independently selected from at least one of C1-C3 alkyl, C1-C3 haloalkyl, C2-C3 alkenyl, C2-C3 haloalkenyl, C2-C3 alkynyl or C2-C3 haloalkynyl; R3, R6 are independently selected from at least one of C1-C3 alkylene, C1-C3 haloalkylene, C2-C3 alkenylene or C2-C3 haloalkenylene.

3. The lithium ion battery electrolyte according to claim 1, characterized in that: The first additive is selected from at least one of the following structures: The second additive is selected from at least one of the following structures:

4. The electrolyte for lithium ion batteries according to claim 1, characterized in that: The amount of the first additive is 0.1-10.0% of the total mass of the electrolyte, and the amount of the second additive is 0.05-5.0% of the total mass of the electrolyte.

5. The electrolyte for lithium-ion batteries according to claim 1, characterized in that: The amount of the first additive is 0.1-2.0% of the total mass of the electrolyte, and the amount of the second additive is 0.1-2.0% of the total mass of the electrolyte.

6. The electrolyte for lithium-ion batteries according to claim 1, characterized in that: The electrolyte further comprises a third additive, the third additive is selected from at least one of carbonate additive and its derivative, fluorine-containing lithium salt additive, and the amount is 0.01-5.0% of the total mass of the electrolyte.

7. The lithium-ion battery electrolyte of claim 6, wherein: The third additive is selected from at least one of vinylene carbonate, fluorinated ethylene carbonate, lithium difluorophosphate, lithium bisfluorosulfonimide, lithium bis-trifluoromethylsulfonimide, lithium bis-oxalate difluorophosphate, lithium difluoro-oxalato-borate or lithium tetrafluoroborate, and the amount is 0.1-5.0% of the total mass of the electrolyte, and the third additive is different from the main lithium salt.

8. The electrolyte for lithium-ion batteries according to claim 1, characterized in that: The main lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bisfluorosulfonimide or lithium bis-trifluoromethylsulfonimide, and the molar concentration in the electrolyte is 0.4-1.6 mol / L; The organic solvent is selected from at least one of C3-C6 carbonate compound, C3-C8 carboxylate compound, sulfone compound and ether compound.

9. The lithium-ion battery electrolyte of claim 8, wherein: The main lithium salt is lithium hexafluorophosphate, and the molar concentration in the electrolyte is 0.6-1.2 mol / L; The C3-C6 carbonate compound is at least one selected from ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoroethylene carbonate, and difluoroethylene carbonate; The C3-C8 carboxylic acid ester compound is at least one selected from γ-butyrolactone, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl acetate, propyl propionate, fluoroethyl acetate, and (2,2-difluoroethyl) acetate; The sulfone compound is at least one selected from tetramethylene sulfone, dimethyl sulfoxide, dimethyl sulfone, and diethyl sulfone; The ether compound is at least one selected from triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

10. A lithium ion battery comprising a positive electrode, a negative electrode, a separator, characterized in that: The lithium ion battery further comprises the lithium ion battery electrolyte according to any one of claims 1-9.

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