Lithium ion electrolyte and lithium ion battery

Abstract

The application provides a lithium ion electrolyte and a lithium ion battery, and belongs to the technical field of battery electrolytes.The lithium ion battery electrolyte comprises a lithium salt, a solvent, a film-forming additive and a film-forming modifier.The film-forming modifier comprises a compound A shown in formula 1 and a compound B shown in formula 2.The synergistic effect of the compound A and the compound B can form a stable, dense and small-impedance SEI film on the positive and negative electrode materials of the battery together with the film-forming additive, improves the structural stability of the positive and negative electrode materials, and makes the electrolyte relatively stable under a high-temperature environment and less in side reactions, thereby effectively improving the interface stability under a high-temperature environment above 60 DEG C, improving the cycle stability and the storage stability.The lithium ion battery obtained by using the lithium ion battery electrolyte has a storage capacity retention rate of 80.12% to 98.98% under a 70 DEG C storage for 28 days and a cycle capacity retention rate of 79.1% to 98.8% under a 60 DEG C cycle.

Description

Technical Field

[0001] This invention belongs to the field of battery electrolyte technology, specifically relating to a lithium-ion battery electrolyte and a lithium-ion battery. Background Technology

[0002] High-capacity lithium-ion batteries have great application prospects in fields such as consumer power supplies for mobile phones and laptops, as well as vehicle power supplies for automobiles, due to their characteristics of large capacity, high specific energy, long cycle life, and no environmental pollution. Therefore, they have attracted the attention of many scientists.

[0003] As the application of lithium-ion batteries becomes more widespread, the performance requirements for them are also increasing, especially for military lithium-ion batteries, which must meet the requirements for operation in both normal and high-temperature environments above 60°C. At 60°C, the output performance of ordinary lithium-ion batteries deteriorates rapidly.

[0004] From the perspective of factors affecting lithium-ion batteries, improving the high-temperature performance of batteries by optimizing the electrolyte composition is the most economical approach. Therefore, developing a highly stable, efficient electrolyte with excellent electrochemical performance for use in lithium-ion batteries to improve their high-temperature performance is an urgent problem that needs to be solved in this field. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a lithium-ion battery electrolyte and a lithium-ion battery with excellent high-temperature performance.

[0006] One objective of this invention is to provide a lithium-ion battery electrolyte, which includes lithium salt, solvent, film-forming additives, and film-forming modifiers. The film-forming modifier includes compound A as shown in Formula 1 and compound B as shown in Formula 2.

[0007] Wherein, R1 is any one of hydrogen, C3-C6 silyl group, halogen, optionally substituted amino group, optionally substituted C1-C7 alkyl group or optionally substituted C3-C9 olefin group.

[0008] R2 and R3 are each independently selected from hydrogen, C3-C6 silane, halogen, optionally substituted C1-C7 alkyl or optionally substituted C3-C9 olefin. Preferably, the mass percentage of compound A in the lithium-ion battery electrolyte is 0.1-3%.

[0009] Preferably, the mass percentage of compound B in the lithium-ion battery electrolyte is 0.1-3%.

[0010] Preferably, the molar ratio of compound A to compound B is 1.5 to 2.5:1, more preferably 2:1.

[0011] Preferably, R1 includes any one of halogen, unsubstituted C1-C3 alkyl, halogen-substituted C1-C3 alkyl, or C3-C6 vinyl, and more preferably includes any one of -H, -F, -CH3, -CH2CH3, -CH2CH2CH3, -CF3, -CH=CH2, or -CH2CH=CH2; Preferably, R2 and R3 each independently comprise an unsubstituted C1-C6 alkyl, an amino-substituted C1-C6 alkyl, or a silane, and more preferably comprise any one of -CH3, -CH2CH3, -CH(CH3)2, -CH(CH3)3, cyclohexyl, or -CH2CH2CH2N(CH3)3.

[0012] Preferably, the structure of compound A includes one or more of the compounds described in the following formula.

[0013] Preferably, compound B comprises one or more of the compounds described below; Preferably, the film-forming additive includes one or more of carbonates, sulfates, phosphoric acids, boric acids, silanes, fluorocarbonates, fluorosulfates, fluorophosphates, fluoroboronic acids, or fluorosilanes.

[0014] Preferably, the film-forming additive includes one or more of vinylene carbonate, 1,3-propane sulphol, fluoroethylene carbonate, tris(trimethylsilane) phosphate, or vinyl sulfate.

[0015] Preferably, the film-forming additive has a mass percentage content of 0.05-5% in the lithium-ion battery electrolyte.

[0016] Preferably, the solvent includes carbonate organic solvents.

[0017] In this invention, the total weight of the lithium-ion battery electrolyte is 100%, and the remainder, excluding lithium salt, film-forming additives, compound A and compound B, is solvent.

[0018] Preferably, the carbonate organic solvent includes any one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate.

[0019] Preferably, the solvent includes ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0020] Preferably, the mass ratio of ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate is 3:2:5.

[0021] Preferably, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium bis-(trifluoromethanesulfonyl)imine, lithium bis(fluorosulfonyl)imine, lithium difluorophosphate, lithium tetrafluoroborate, or lithium difluorobis(oxalato)borate.

[0022] Preferably, the lithium salt has a mass percentage content of 7.5% to 18.5% in the lithium-ion battery electrolyte.

[0023] A second objective of this invention is to provide a lithium-ion battery, wherein the lithium-ion battery includes the lithium-ion battery electrolyte as described above.

[0024] The beneficial effects of this invention include: This invention incorporates compounds A and B as film-forming modifiers. Their synergistic effect, together with film-forming additives, allows for the formation of a stable, dense, and low-resistivity SEI film on the positive and negative electrode materials of the battery. This improves the structural stability of the electrode materials, enhances the relative stability of the electrolyte at high temperatures, reduces side reactions, and effectively improves interfacial stability above 60°C, as well as cycle and storage stability. Lithium-ion batteries using the electrolyte described in this invention exhibit a storage capacity retention of 80.12%–98.98% after 28 days of storage at 70°C and a cycle capacity retention of 79.1%–98.8% at 60°C. Detailed Implementation

[0025] The following description includes certain specific details to provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that the embodiments can be implemented without employing one or more of these specific details, but using other methods, components, materials, etc.

[0026] Unless otherwise required in this application, the words “including” and “comprising” shall be interpreted in an open-ended, inclusive sense, meaning “including but not limited to”.

[0027] Throughout this specification, the terms "an embodiment," "an embodiment," "a preferred embodiment," or "some embodiments" refer to including, in at least one embodiment, a specific reference element, structure, or feature associated with that embodiment. Therefore, the phrases "in an embodiment," "in a preferred embodiment," or "in some embodiments" appearing in different places throughout the specification do not necessarily all refer to the same embodiment. Furthermore, specific elements, structures, or features may be combined in one or more embodiments in any suitable manner.

[0028] According to a first aspect of the present invention, a lithium-ion battery electrolyte is provided, the lithium-ion battery electrolyte comprising a lithium salt, a solvent, a film-forming additive, and a film-forming modifier; The film-forming modifier includes compound A as shown in Formula 1 and compound B as shown in Formula 2.

[0029] Wherein, R1 is any one of hydrogen, C3-C6 silyl group, halogen, optionally substituted amino group, optionally substituted C1-C7 alkyl group or optionally substituted C3-C9 olefin group.

[0030] R2 and R3 are each independently selected from hydrogen, C3-C6 silane, halogen, optionally substituted C1-C7 alkyl or optionally substituted C3-C9 olefin. In this invention, the film-forming additive refers to an additive that forms a solid electrolyte interface (SEI) film. During the initial charge and discharge process of a lithium-ion battery, the film-forming additive reacts at the solid-liquid interface between the electrode material and the electrolyte to form a passivation film, i.e., the SEI film, covering the surface of the electrode material. The SEI film is an electronic insulator and also a lithium electrolyte interphase (SEE) film. + Li is an excellent conductor. + Electrodes can freely insert into and extract from the SEI film. The SEI film protects the electrode material, making the material structure less prone to collapse, thereby increasing the cycle life of the electrode material.

[0031] In this invention, compound B can react with water and active hydrogen to act as an acid and water removal additive. Furthermore, compound B can synergistically work with compound A to form a sulfur- and nitrogen-rich SEI film on the electrode, effectively improving interfacial stability at high temperatures above 60°C, as well as enhancing cycle stability and storage stability. The pyridine in compound A can complex with transition metal ions dissolved from the positive electrode, preventing their migration and destruction of the SEI film, reducing electrolyte loss due to SEI film reconstruction, and improving storage stability and cycle life. The nitrogen atom on the pyridine ring in compound A can capture oxygen ions released from the positive electrode or electrolyte decomposition, preventing further reaction with electrolyte components, improving electrolyte stability, and enhancing high-temperature storage performance.

[0032] Preferably, R1 comprises any one of halogen, unsubstituted C1-C3 alkyl, halogen-substituted C1-C3 alkyl, or C3-C6 vinyl, and R1 is, for example, -H, -F, -CH3, -CH2CH3, -CH2CH2CH3, -CF3, -CH=CH2, or -CH2CH=CH2.

[0033] Preferably, R2 and R3 each independently comprise an unsubstituted C1-C6 alkyl, an amino-substituted C1-C6 alkyl, or a silane, such as -CH3, -CH2CH3, -CH(CH3)2, -CH(CH3)3, cyclohexyl, or -CH2CH2CH2N(CH3)3.

[0034] In a preferred embodiment of the present invention, the mass percentage of compound A in the lithium-ion battery electrolyte is 0.1-3%, and the mass percentage of compound B in the lithium-ion battery electrolyte is 0.1-3%.

[0035] In this invention, if the amount of compound A and compound B added is too small, when applied to lithium-ion batteries, a sufficiently stable SEI film cannot be formed on the surface of the electrode material, resulting in insufficient structural stability of the positive and negative electrode materials, which in turn leads to poor cycle performance of the battery. If the amount of compound A and compound B added is too large, the SEI film formed on the surface of the electrode material is too thick, which on the one hand affects lithium-ion transport, and on the other hand consumes too many lithium ions, affecting the coulombic efficiency of the lithium-ion battery and reducing cycle life.

[0036] In this invention, the mass percentage of compound A is 0.1% to 3%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%, and specific values ​​between the above values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0037] In this invention, the mass percentage of compound B is 0.1% to 3%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0038] In a preferred embodiment of the present invention, the molar ratio of compound A to compound B is 1.5 to 2.5:1, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1 or 2.5:1, preferably 2:1.

[0039] In a preferred embodiment of the present invention, the structure of compound A includes one or more of the compounds described in the following formula; In a preferred embodiment of the present invention, compound B includes one or more of the compounds described below; In a preferred embodiment of the present invention, the structure of compound A is shown in Formula 1-2, and the structure of compound B is shown in Formula 2-1; .

[0040] In this invention, F can improve the chemical stability of pyridine, thereby improving the high-voltage tolerance of the electrolyte to some extent. Silicon is an anion acceptor, similar to PF6. - or F - Combining can improve Li ＋ Mobility, while silane groups can modify the SEI film of the electrode to improve ionic conductivity and reduce impedance.

[0041] In a preferred embodiment of the present invention, the film-forming additive includes one or more of carbonates, sulfates, phosphoric acids, boric acids, silanes, fluorocarbonates, fluorosulfates, fluorophosphates, fluoroboronic acids, or fluorosilanes.

[0042] Preferably, the film-forming additive includes one or more of vinylene carbonate, 1,3-propane sulphol, fluoroethylene carbonate, tris(trimethylsilane) phosphate, or vinyl sulfate.

[0043] In this invention, the film-forming additive is, for example, vinylene carbonate, 1,3-propane sulphol, fluoroethylene carbonate, tris(trimethylsilane) phosphate, vinyl sulfate, vinylene carbonate and 1,3-propane sulphol, vinylene carbonate and fluoroethylene carbonate, vinylene carbonate and vinyl sulfate, or a combination of vinylene carbonate, 1,3-propane sulphol, and fluoroethylene carbonate.

[0044] Preferably, the film-forming additive has a mass percentage content of 0.05-5% in the lithium-ion battery electrolyte, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, or 4.8%.

[0045] In a preferred embodiment of the present invention, the solvent includes a carbonate organic solvent.

[0046] Preferably, the carbonate organic solvent includes any one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate.

[0047] In this invention, the organic solvent is, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate and propylene carbonate, ethylene carbonate and dimethyl carbonate, propylene carbonate and dimethyl carbonate, ethylene carbonate, propylene carbonate and dimethyl carbonate, or a combination of propylene carbonate, dimethyl carbonate and diethyl carbonate.

[0048] In a preferred embodiment of the present invention, the solvent includes ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0049] Preferably, the mass ratio of ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate is 3:2:5.

[0050] In a preferred embodiment of the present invention, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium bis-(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate, or lithium difluorobis(oxalato)borate.

[0051] In this invention, the lithium salt is, for example, lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium bis-(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate, or lithium difluorobis(oxalato)phosphate, lithium hexafluorophosphate and lithium bis(oxalato)borate, lithium hexafluorophosphate and lithium difluorooxalatoborate, lithium bis(oxalato)borate and lithium difluorooxalatoborate, or a combination of lithium hexafluorophosphate, lithium bis(oxalato)borate and lithium difluorooxalatoborate.

[0052] Preferably, the lithium salt has a mass percentage content of 7.5% to 18.5% in the lithium-ion battery electrolyte, for example, 7.6%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, or 18.4%.

[0053] In a preferred embodiment of the present invention, the method for preparing the lithium-ion battery electrolyte includes first adding lithium salt to a solvent to dissolve it, then adding a film-forming additive, compound A and compound B, and mixing them evenly.

[0054] According to another aspect of the present invention, a lithium-ion battery is provided, the lithium-ion battery comprising the lithium-ion battery electrolyte as described above.

[0055] In a preferred embodiment of the present invention, the lithium-ion battery includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte as described above.

[0056] Preferably, the positive and negative electrodes comprise an active material, a conductive agent, a current collector, and a binder that combines the active material with the conductive agent and the current collector.

[0057] Specifically, the method for preparing the lithium-ion battery includes: Lithium nickel cobalt manganese oxide, positive electrode binder, carbon and conductive carbon black are mixed to form a positive electrode slurry; A negative electrode slurry is prepared by mixing carbon, conductive carbon black, carboxymethyl cellulose and styrene-butadiene rubber. Then, the positive electrode slurry is coated onto the aluminum foil current collector, and the negative electrode slurry is coated onto the copper foil current collector. After drying, the positive electrode sheet and the negative electrode sheet are obtained. The positive and negative electrode sheets are encapsulated with a polyethylene separator, dried, and then injected with electrolyte to form the lithium-ion battery.

[0058] Example The following description includes certain specific details to provide a comprehensive understanding of the various disclosed embodiments. However, those skilled in the art will recognize that the embodiments can be implemented without employing one or more of these specific details, but using other methods, components, materials, etc.

[0059] Unless otherwise required in this application, the words “including” and “comprising” shall be interpreted in an open-ended, inclusive sense, meaning “including but not limited to”.

[0060] Throughout this specification, the terms "an embodiment," "an embodiment," "a preferred embodiment," or "some embodiments" refer to including, in at least one embodiment, a specific reference element, structure, or feature related to that embodiment. Therefore, the phrases "in an embodiment," "in a preferred embodiment," or "in some embodiments" appearing in different places throughout the specification do not necessarily all refer to the same embodiment. Furthermore, specific elements, structures, or features may be combined in one or more embodiments in any suitable manner.

[0061] raw material Solvent: Ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC) in a mass ratio of 3:2:5; Lithium salt: Lithium hexafluorophosphate (LiPF6); Film-forming additive: vinylene carbonate (VC); Regarding compound A and compound B: Example 1 uses compound A as shown in Formula 1-1 and compound B as shown in Formula 2-3; Examples 2 and 7-13 used compound A as shown in Formula 1-2 and compound B as shown in Formula 2-1; Example 3 uses compound A as shown in Formula 1-3 and compound B as shown in Formula 2-2; Example 4 uses compound A as shown in Formulas 1-4 and compound B as shown in Formulas 2-4; Example 5 uses compound A as shown in Formulas 1-5 and compound B as shown in Formulas 2-5; Example 6 uses compound A as shown in Formulas 1-2 and compound B as shown in Formulas 2-6; Comparative Example 1 does not use compounds A and B; Comparative Example 2 uses only compound A as shown in Formula 1-2, without using compound B; Comparative Example 3 uses only compound B as shown in Formula 2-1, without using compound A; The amount of each raw material added in Examples 1-13 and Comparative Examples 1-3 is shown in Table 1.

[0062] Table 1. Amounts of each raw material added in Examples 1-13 and Comparative Examples 1-3 Lithium-ion batteries were prepared using the lithium-ion battery electrolytes obtained in Examples 1-13 and Comparative Examples 1-3. The preparation methods are as follows: A positive electrode slurry was prepared by mixing lithium nickel cobalt manganese oxide (NCM523), positive electrode binder (PVDF), carbon (C), and conductive carbon black (Super-P) in a mass ratio of 95.5:2:1:1.5. A negative electrode slurry was prepared by mixing carbon (C), conductive carbon black (Super-P), carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) in a mass ratio of 95.9:0.5:1.5:2.1. The positive electrode slurry is coated onto an aluminum foil current collector, and the negative electrode slurry is coated onto a copper foil current collector. After drying, the positive electrode sheet and the negative electrode sheet are obtained. Then, the positive and negative electrode sheets were encapsulated with a polyethylene separator, dried, and 6.5 g of the electrolyte prepared as in Examples 1-13 and Comparative Examples 1-3 were injected. After formation, the lithium-ion battery was obtained, and its electrical performance was tested.

[0063] Performance testing: (1) 70℃ storage capacity retention rate: The prepared lithium-ion battery was placed in a 70℃ oven and stored for 28 days. Then it was placed in a battery testing system (Xinwei Testing System CT-ZWJ-4'S-T-1U) and discharged at 1 C to test its capacity retention rate. Capacity retention rate = discharge capacity after storage / discharge capacity before storage.

[0064] (2) 60℃ cycle capacity retention rate: The prepared lithium-ion battery was placed in a 60℃ oven and connected to a battery testing system (Xinwei Testing System CT-ZWJ-4'S-T-1U). It was charged to 4.35V at 1C (the charging cutoff current was 0.05C) and discharged to 2.75V at 1C. The charge-discharge cycle was repeated for 200 cycles to test the capacity retention rate of the lithium-ion battery.

[0065] The test results of lithium-ion batteries prepared using the lithium-ion battery electrolytes prepared in Examples 1-13 and Comparative Examples 1-3 are shown in Table 2.

[0066] Table 2 Test Results

Claims

1. A lithium-ion battery electrolyte, characterized in that, The lithium-ion battery electrolyte includes lithium salt, solvent, film-forming additives, and film-forming modifiers; The film-forming modifier includes compound A as shown in Formula 1 and compound B as shown in Formula 2; Wherein, R1 is any one of hydrogen, C3-C6 silyl group, halogen, optionally substituted amino group, unsubstituted C1-C3 alkyl group, vinyl group, optionally substituted C1-C7 alkyl group or optionally substituted C3-C9 olefin group; R2 and R3 are each independently selected from any one of hydrogen, C3-C6 silyl groups, halogens, unsubstituted C1-C6 alkyl groups, optionally substituted C1-C7 alkyl groups, or optionally substituted C3-C9 olefin groups; With the total weight of the lithium-ion battery electrolyte as 100%, the mass percentage of compound A in the lithium-ion battery electrolyte is 0.1-3%; and the mass percentage of compound B in the lithium-ion battery electrolyte is 0.1-3%.

2. The lithium-ion battery electrolyte as described in claim 1, characterized in that, The molar ratio of compound A to compound B is 1.5 to 2.5:

1.

3. The lithium-ion battery electrolyte as described in claim 1 or 2, characterized in that, The R1 includes halogen-substituted C1-C3 alkyl groups; R2 and R3 each independently comprise an amino-substituted C1-C6 alkyl group.

4. The lithium-ion battery electrolyte as described in claim 1 or 2, characterized in that, The structure of compound A includes one or more of the compounds described in the following formula; 5. The lithium-ion battery electrolyte as described in claim 1 or 2, characterized in that, Compound B includes one or more of the compounds described below; 6. The lithium-ion battery electrolyte as described in claim 1, characterized in that, The film-forming additives include one or more of the following: carbonates, sulfates, phosphoric acids, boric acids, silanes, fluorocarbonates, fluorosulfates, fluorophosphates, fluoroboronic acids, or fluorosilanes. With the total weight of the lithium-ion battery electrolyte as 100%, the mass percentage of the film-forming additive in the lithium-ion battery electrolyte is 0.05~5%.

7. The lithium-ion battery electrolyte as described in claim 1, characterized in that, The solvent includes carbonate organic solvents.

8. The lithium-ion battery electrolyte as described in claim 1 or 7, characterized in that, The solvents include ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate; The mass ratio of ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate is 3:2:

5.

9. The lithium-ion battery electrolyte as described in claim 1, characterized in that, The lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium bis-(trifluoromethylsulfonyl)imine, lithium bis(fluorosulfonyl)imine, lithium difluorophosphate, lithium tetrafluoroborate, or lithium difluorobis(oxalato)borate. With the total weight of the lithium-ion battery electrolyte as 100%, the mass percentage of the lithium salt in the lithium-ion battery electrolyte is 7.5% to 18.5%.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the lithium-ion battery electrolyte as described in any one of claims 1 to 9.

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