Electrolyte additive, electrolyte and application thereof

Abstract

The application provides an electrolyte additive, an electrolyte and application thereof, and the general formula of the electrolyte additive is: wherein R1-R9 are independently alkyl groups with 1-3 carbon atoms. The application provides an electrolyte additive, an electrolyte and application thereof, which can greatly improve the cycle performance of a lithium ion battery and reduce the high-temperature gas production of the lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of power electrochemical energy storage technology, specifically to an electrolyte additive, an electrolyte, and their applications. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles due to their high energy density and long cycle life. However, with the development of the electric vehicle industry, driving range has become a major limiting factor for the further development of lithium-ion batteries. Increasing the operating voltage of lithium-ion batteries is one common method to improve driving range, but this comes at the cost of deterioration in the battery's cycle life, gas generation, and storage performance.

[0003] Currently, improvements to increase the voltage of lithium-ion batteries can lead to problems such as increased electrolyte viscosity, decreased kinetic performance, cathode oxidation, or excessive impedance, thus limiting the development of lithium-ion batteries. Summary of the Invention

[0004] This invention proposes an electrolyte additive, an electrolyte, and their applications to improve the cycle stability of lithium-ion batteries and effectively improve the high-temperature gas generation and cycle performance of lithium-ion batteries.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution.

[0006] This invention provides an electrolyte additive, the general formula of which is: Equation (I); Among them, R1 to R9 are each independently a C1 to C3 alkane group.

[0007] In one embodiment of the present invention, R1 to R9 are each methyl groups.

[0008] The present invention also provides a lithium-ion battery electrolyte, comprising: Non-aqueous solvents; Electrolytes; and Additives, including the electrolyte additives described above.

[0009] In one embodiment of the present invention, the additive further includes a film-forming additive, which includes one or more of lithium bis(fluorosulfonyl)imide, vinyl sulfate, vinylene carbonate, or fluorovinyl carbonate.

[0010] In one embodiment of the present invention, the film-forming additive has a mass content of 3%-10% in the electrolyte.

[0011] In one embodiment of the present invention, the non-aqueous solvent includes one or more combinations of ethylene carbonate, polycarbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, propyl propionate, ethyl propionate, or ethyl acetate.

[0012] In one embodiment of the present invention, the electrolyte includes one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalate-borate), lithium difluorobis(oxalate-phosphate), lithium difluorooxalate-borate, lithium difluorophosphate, or lithium trifluoromethanesulfonate.

[0013] In one embodiment of the present invention, the mass content of the electrolyte in the electrolyte solution is 10%-15%.

[0014] The present invention also provides a lithium-ion battery, comprising the lithium-ion battery electrolyte described above.

[0015] The present invention also provides an electrochemical device comprising the lithium-ion battery described above.

[0016] In summary, this invention proposes an electrolyte additive, an electrolyte, and their applications, which can effectively reduce the impedance growth of lithium-ion batteries and effectively suppress the oxidation of the electrolyte by oxygen released from the cathode. It can effectively absorb hydrofluoric acid in the electrolyte, effectively reducing the corrosion of the cathode by hydrofluoric acid, decreasing cell impedance, and thus effectively suppressing the impact of cathode oxidation on lithium-ion battery performance, thereby improving lithium-ion battery performance. It can promote film formation on the negative electrode, improve the cycle stability of lithium-ion batteries, further improve the formation quality of the SEI film, and effectively improve the high-temperature gas generation and cycle performance of lithium-ion batteries. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0018] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0019] The technical solution of the present invention will be further described in detail below with reference to several embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention proposes an electrolyte additive, the general formula of which is: Equation (Ⅰ). In formula (Ⅰ), R1~R9 are each an independent C1~C3 alkane group; in this embodiment, R1~R9 are each methyl groups. The polyunsaturated double bonds in the electrolyte additive enable the compound to polymerize, increasing the polymer content in the electrolyte and preventing the regeneration of oligomers after dissolving in the electrolyte, thus effectively reducing impedance growth during use. However, the presence of double bonds may affect the initial direct current resistance (DCR) of the lithium-ion battery. Combined with the effect of suppressing impedance growth during use, the overall performance of the lithium-ion battery is improved. The boron atoms in the electrolyte additive have electron-deficient characteristics, which can effectively suppress the oxidation of the electrolyte by oxygen released from the cathode. The trimethylsilyl group in the electrolyte additive can effectively absorb hydrofluoric acid (HF) in the electrolyte, effectively reducing the corrosion of the cathode by HF and decreasing the cell impedance. The electrolyte additive provided by this invention can improve the combination of the three functional groups, effectively suppressing the impact of cathode oxidation on the performance of lithium-ion batteries.

[0021] This invention also proposes a lithium-ion battery electrolyte, comprising at least a non-aqueous solvent, an electrolyte, and additives, wherein the additives include one or a mixture of several electrolyte additives with the structure of formula (1) above. By adding electrolyte additives with the structure of formula (1), sufficient amounts of unsaturated double bonds, boron atoms, and methylsilicon groups can be provided, thereby improving the performance of lithium-ion batteries and enhancing their performance.

[0022] In one embodiment of the present invention, the additive further includes a film-forming additive, which includes one or more combinations of lithium bis(fluorosulfonyl)imide (LiFSI), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide, DTD), vinylene carbonate (VC), or fluoroethylene carbonate (FEC). In one embodiment of the present invention, the film-forming additive has a mass content of 3%-10% in the electrolyte to promote film formation at the negative electrode and improve the cycle stability of the lithium-ion battery. The combined effect of multiple additives can further improve the formation quality of the SEI film and effectively improve the high-temperature gas generation and cycle performance of the lithium-ion battery.

[0023] In one embodiment of the present invention, the electrolyte is, for example, a lithium salt, selected from any one or a combination of at least two of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalateborate)borate (LiBOB), lithium difluorobis(oxalateborate)phosphate (LiODFP), lithium difluorooxalateborate (LiODFB), lithium difluorophosphate (LiPO2F2), or lithium trifluoromethanesulfonate (LiCF3SO3). In this embodiment, the electrolyte is, for example, sodium hexafluorophosphate, and the mass content of the electrolyte in the electrolyte solution is, for example, 8%-15%, or, for example, 13%.

[0024] In one embodiment of the present invention, the non-aqueous solvent includes, for example, one or a combination of at least two of the following: ethylene carbonate (EC), polycarbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), propyl propionate (PP), ethyl propionate (EP), or ethyl acetate (EA).

[0025] In one embodiment of the present invention, when preparing the electrolyte, the nitrogen content in the glove box is 99.999%, the actual oxygen content in the glove box is less than or equal to 0.1 ppm, and the moisture content is less than or equal to 0.1 ppm. After the non-aqueous mixture is mixed evenly according to the mass ratio, the fully dried electrolyte is added to the above-mentioned non-aqueous solvent, and additives are added according to the ratio to prepare the lithium-ion battery electrolyte.

[0026] This invention also proposes a lithium-ion battery, comprising a positive electrode, a separator, a negative electrode, and an electrolyte. The separator is located between the positive and negative electrodes, and the electrolyte is filled between the positive electrode, the separator, and the negative electrode. The electrolyte is the lithium-ion battery electrolyte described above. The lithium-ion battery can be, for example, a primary battery or a secondary battery. A secondary battery can be, for example, a pouch battery, a hard-case battery, or a cylindrical battery, etc. This invention does not impose specific limitations.

[0027] In one embodiment of the present invention, the positive electrode sheet includes a positive electrode material, a positive electrode current collector, a binder, and a conductive agent. The positive electrode current collector is, for example, a foil formed by surface treatment of materials such as nickel, titanium, aluminum, silver, stainless steel, or carbon. Besides foil, the positive electrode current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam, or non-woven fabric. The thickness of the positive electrode current collector is, for example, 8μm-15μm. In this embodiment, the positive electrode current collector is, for example, aluminum foil, and the thickness of the aluminum foil is, for example, 13μm.

[0028] In one embodiment of the present invention, the cathode material is selected from any one or a combination of at least two of the following cathode materials: lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide. For example, lithium iron phosphate, lithium cobalt oxide, or lithium nickel cobalt manganese oxide are selected. The general formula for lithium nickel cobalt manganese oxide is LiNi. x Co y Mn z O2, and x+y+z=1. The adhesive is selected from one or more of the following: polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinyl ether, polymethyl methacrylate (PMMA), ethylene-propylene-diene terpolymer (EPDM), polyhexanefluoropropylene (Polyhexafluoropropylene), or polymerized styrene-butadiene rubber (SBR). The conductive agent is selected from one or more of the following: carbon black, acetylene black, carbon nanotubes, and graphene.

[0029] In one embodiment of the present invention, the positive electrode material is, for example, lithium iron phosphate, the binder is, for example, polyvinylidene fluoride, and the conductive agent is, for example, acetylene black. The positive electrode material, acetylene black, and polyvinylidene fluoride are mixed, for example, in a weight ratio of 95:3:2, and an organic solvent is added and stirred until the system is homogeneous to obtain a positive electrode slurry. The organic solvent is, for example, N-methylpyrrolidone (NMP). The positive electrode slurry is uniformly coated onto aluminum foil and dried. Then, through processes such as rolling and cutting, a positive electrode sheet is obtained.

[0030] In one embodiment of the present invention, the negative electrode sheet includes, for example, a negative electrode current collector, a negative electrode material, a binder, and a conductive agent. The negative electrode current collector is selected from, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foamed copper current collector, or a stainless steel current collector, and the thickness of the negative electrode current collector is, for example, 8 μm-15 μm. In this embodiment, the negative electrode current collector is, for example, copper foil, and the thickness of the copper foil is, for example, 13 μm.

[0031] In one embodiment of the present invention, the negative electrode material is selected from any one or a combination of at least two of the following: artificial graphite, natural graphite, soft carbon, hard carbon, pure silicon, silicon oxide compounds, or silicon carbide compounds. The binder is selected from any one or more of the following: polyvinylidene fluoride, polyamide, polypropylene, polyacrylate, polyethylene ether, sodium carboxymethyl cellulose, polymethyl methacrylate, polyhexamethylene propylene, or styrene-butadiene rubber. The conductive agent is selected from any one or more of the following: conductive carbon black, acetylene black, carbon nanotubes, and graphene.

[0032] In one embodiment of the present invention, the negative electrode current collector is selected, for example, from copper foil; the negative electrode material is selected, for example, from artificial graphite; the conductive agent is selected, for example, from acetylene black; and the binder is selected, for example, from sodium carboxymethyl cellulose. In one embodiment of the present invention, graphite, acetylene black, and sodium carboxymethyl cellulose are mixed, for example, at a mass ratio of 96:2:2, deionized water is added, and the mixture is stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated onto copper foil, and the negative electrode sheet is obtained through processes such as drying, rolling, and cutting.

[0033] In one embodiment of the present invention, the separator is, for example, a polyethylene (PE) film, a polypropylene (PP) film, a glass fiber film, a polyethylene film, or a composite film. The thickness of the separator is, for example, 9μm-15μm. In this embodiment, a polyethylene film is selected as the separator. In one embodiment of the present invention, the above-mentioned positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrode to act as a separator, and the stacked sheets form a bare battery cell. The bare battery cell is placed in an aluminum-plastic film, then baked at 80°C to remove water, followed by the injection of electrolyte and sealing. Afterwards, it undergoes processes such as settling, hot and cold pressing, formation, clamping, and capacity testing to obtain a finished soft-pack lithium-ion secondary battery.

[0034] The present invention will be explained in more detail below by referring to embodiments, which should not be construed as limiting. Appropriate modifications can be made within the scope of the present invention, and all such modifications fall within the technical scope of the present invention.

[0035] Example 1 Electrolyte preparation: Under conditions of 99.999% nitrogen content, 0.1 ppm actual oxygen content, and 0.1 ppm moisture content in a glove box, EC, EMC, and DEC were mixed in a mass ratio of 30:50:20. 13% lithium hexafluorophosphate and 0.1% electrolyte additive of formula (I) were mixed thoroughly with the solvent to obtain the electrolyte.

[0036] Preparation of the positive electrode sheet: LiFePO4 (positive electrode material), acetylene black (conductive agent), and polyvinylidene fluoride (binder) were mixed in a mass ratio of 95:3:2. N-methylpyrrolidone (N-methylpyrrolidone) was added as solvent, and the mixture was stirred until it became homogeneous and transparent to obtain the positive electrode slurry. The positive electrode slurry was uniformly coated onto a 13 μm aluminum foil current collector, and then dried, rolled, and cut to obtain the positive electrode sheet.

[0037] Preparation of the negative electrode sheet: Artificial graphite (negative electrode material), acetylene black (conductive agent), and sodium carboxymethyl cellulose (binder) are mixed in a mass ratio of 96:2:2. Deionized water is added, and the mixture is stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated onto a 13 μm copper foil, and after drying, rolling, and cutting, the negative electrode sheet is obtained.

[0038] Selection of diaphragm: For example, 9μm polyethylene is selected as the diaphragm.

[0039] Battery fabrication: The positive electrode, separator, and negative electrode are stacked sequentially, with the separator positioned between the positive and negative electrodes to provide insulation. This stacking process yields a bare battery cell. The cell is then wrapped in an aluminum-plastic film, transferred to a vacuum oven, dried at 80°C, injected with electrolyte, and sealed. Following static settling, hot and cold pressing, formation, clamping, and capacity testing, a lithium-ion secondary battery is obtained.

[0040] Example 2 EC, EMC, and DEC were mixed in a mass ratio of 30:50:20. 12% lithium hexafluorophosphate, 4% lithium difluorosulfonylimide, and 0.1% electrolyte additive of formula (I) were mixed thoroughly with the solvent to obtain the electrolyte. The remaining steps were the same as in Example 1.

[0041] Example 3 EC, PC, EMC, DMC, and PP were mixed in a mass ratio of 10:10:40:20:20. 13% lithium hexafluorophosphate and 0.1% electrolyte additive of formula (I) were mixed evenly with the solvent to obtain the electrolyte. The remaining steps were the same as in Example 1.

[0042] Example 4 EC, EMC, DEC, and EA were mixed in a mass ratio of 20:50:20:10. 12% lithium hexafluorophosphate, 4% lithium difluorosulfonyl imide, 1% vinyl sulfate, 1% fluoroethylene carbonate, and 0.2% electrolyte additive of formula (I) were mixed thoroughly with the solvent to obtain the electrolyte. The remaining steps were the same as in Example 1.

[0043] Example 5 EC, EMC, DEC, and EP were mixed in a mass ratio of 20:50:20:10. 13% lithium hexafluorophosphate, 2% vinylene carbonate, 1% fluoroethylene carbonate, and 0.1% electrolyte additive of formula (I) were mixed thoroughly with the solvent to obtain the electrolyte. The remaining steps were the same as in Example 1.

[0044] Comparative Example 1 In this comparative example, the electrolyte additive of formula (Ⅰ) in Example 1 was removed, and the remaining conditions were the same as in Example 1.

[0045] Comparative Example 2 In this comparative example, the electrolyte additive of formula (Ⅰ) in Example 2 was removed, and the other conditions were the same as in Example 2.

[0046] Comparative Example 3 In this comparative example, the electrolyte additive of formula (Ⅰ) in Example 3 was removed, and the other conditions were the same as in Example 3.

[0047] Comparative Example 4 In this comparative example, the electrolyte additive of formula (Ⅰ) in Example 4 was removed, and the other conditions were the same as in Example 4.

[0048] Comparative Example 5 In this comparative example, the electrolyte additive of formula (Ⅰ) in Example 5 was removed, and the other conditions were the same as in Example 5.

[0049] In this invention, lithium-ion batteries were prepared using different electrolytes in Examples 1-5 and Comparative Examples 1-5, and the electrolyte formulations are shown in Table 1. The cycle performance, initial DCR, high-temperature storage DCR growth rate, high-temperature storage, and high-temperature gas generation of the lithium-ion batteries were tested, and the test results are shown in Table 2.

[0050] In one embodiment of the present invention, the cycle test is performed at 25°C by charging the lithium-ion battery at a constant current of 1 / 3C to 3.65V, followed by constant voltage charging to a current of 0.05C. The battery is then discharged at a constant current of 1 / 3C to 2.5V. The capacity C0 is recorded. This charge-discharge cycle is repeated 2000 times, and the discharge capacity C1 after 2000 cycles is recorded. The battery capacity retention rate = C1 / C0 * 100%.

[0051] In one embodiment of the present invention, the initial DCR test is performed at 25°C by charging the lithium-ion battery at a constant current of 1 / 3C to 3.65V, and then charging it at a constant voltage to a current of 0.05C. The battery is then discharged at a constant current of 1 / 3C to 2.5V. This charging process is repeated, and the charging capacity is recorded as C2. The battery is then discharged at a constant current of 1 / 3C to (50% * C2), and the initial voltage is recorded as V2. The battery is then discharged at a constant current of 1C for 30 seconds, and the final voltage is recorded as V3. Therefore, the initial DCR = (V2 - V3) / (C2 * 1).

[0052] In one embodiment of the present invention, the lithium-ion battery is stored at 60°C for 27 days. The battery is then discharged at 25°C with a constant current of 1 / 3C to 2.5V, then charged at a constant current of 1 / 3C to 3.65V, and finally charged at a constant voltage to a current of 0.05C. The battery is then discharged at a constant current of 1 / 3C to 2.5V, and the discharge capacity is recorded as C3. The capacity recovery rate is (C3 / C2)*100%. The above charging steps are repeated, and the charging capacity is recorded as C4. The battery is discharged at a constant current of 1 / 3C to (50%*C4), and the initial voltage is recorded as V4. The battery is discharged at a constant current of 1C for 30s, and the final voltage is recorded as V5. After 27 days of storage, the DCR = (V4-V5) / (C4*1). The DCR growth rate is (DCR after 27 days of storage - initial DCR) / initial DCR*100%.

[0053] In one embodiment of the present invention, the high-temperature gas generation test is performed by charging the lithium-ion battery at 25°C with a constant current of 1 / 3C to 3.65V, and then charging it with a constant voltage to a current of 0.05C. The thickness is measured using a thickness gauge, and the initial thickness T1 is recorded. The battery is then stored in a 60°C constant temperature chamber for 30 days. After being removed and cooled to 25°C, the cell thickness T2 is measured using a thickness gauge, and the thickness change rate is calculated as (T2-T1) / T1*100%.

[0054] Table 1. Electrolyte formulations in Examples 1-5 and Comparative Examples 1-5

[0055] Table 2. Performance test results of lithium-ion batteries in Examples 1-5 and Comparative Examples 1-5

[0056] Please refer to Tables 1 and 2. Comparing Examples 1-5 and Comparative Examples 1-5, it can be seen that adding an electrolyte additive with the structure of Formula (I) to the electrolyte can improve the cycle performance, high-temperature storage, and gas generation performance of lithium-ion batteries, and reduce the DCR growth rate of lithium-ion batteries during use. This indicates that although the double bonds in the electrolyte additive with the structure of Formula (I) slightly increase the initial DCR of the lithium-ion battery, they significantly reduce the impedance growth of the lithium-ion battery during use, thereby improving the overall performance of the lithium-ion battery. The boron atoms in the electrolyte additive with the structure of Formula (I) can effectively inhibit the oxidation of the electrolyte by oxygen released from the cathode, and the trimethylsilyl group can effectively reduce the corrosion of the cathode by HF. That is, the electrolyte additive with the structure of Formula (I) can effectively alleviate the performance degradation caused by increasing voltage or other measures that increase the oxidation of the lithium-ion battery cathode, thereby improving the overall performance of the lithium-ion battery.

[0057] Please refer to Tables 1 and 2. Comparing Examples 1-5, it is evident that the combined use of electrolyte additives and film-forming additives with the formula (Ⅰ) structure can further improve the cycle performance of lithium-ion batteries and reduce high-temperature gas generation. This demonstrates that the combined use of multiple additives can promote film formation on the negative electrode, improve the cycle stability of lithium-ion batteries, further enhance the formation quality of the SEI film, and effectively improve the high-temperature gas generation and cycle performance of lithium-ion batteries.

[0058] In summary, this invention proposes an electrolyte additive, an electrolyte, and their applications. The electrolyte additive with the structure of formula (I) effectively reduces impedance growth during use, effectively inhibits the oxidation of the electrolyte by oxygen released from the cathode, effectively absorbs hydrofluoric acid in the electrolyte, effectively reduces the corrosion of the cathode by hydrofluoric acid, and reduces cell impedance. This effectively suppresses the impact of cathode oxidation on lithium-ion battery performance and improves the performance of the lithium-ion battery. The combined use of multiple additives promotes film formation on the negative electrode, improves the cycle stability of the lithium-ion battery, further improves the formation quality of the SEI film, and effectively improves the high-temperature gas generation and cycle performance of the lithium-ion battery.

[0059] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0060] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A lithium-ion battery electrolyte, characterized in that, include: Non-aqueous solvents; Electrolytes; as well as Additives, including electrolyte additives with the general formula (I): Equation (I); Among them, R1 to R9 are each independently a C1 to C3 alkane group.

2. The lithium-ion battery electrolyte according to claim 1, characterized in that, R1 to R9 are each methyl groups.

3. The lithium-ion battery electrolyte according to claim 1, characterized in that, The additives also include film-forming additives, which include one or more of lithium bis(fluorosulfonyl)imide, vinyl sulfate, vinylene carbonate, or fluorovinyl carbonate.

4. The lithium-ion battery electrolyte according to claim 3, characterized in that, The film-forming additive has a mass content of 3%-10% in the electrolyte.

5. The lithium-ion battery electrolyte according to claim 1, characterized in that, The non-aqueous solvent includes one or more combinations of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, propyl propionate, ethyl propionate, or ethyl acetate.

6. The lithium-ion battery electrolyte according to claim 1, characterized in that, The electrolyte includes one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalate)borate, lithium difluorobis(oxalate)phosphate, lithium difluorooxalateborate, lithium difluorophosphate, or lithium trifluoromethanesulfonate.

7. The lithium-ion battery electrolyte according to claim 1, characterized in that, The electrolyte has a mass content of 10%-15% in the electrolyte solution.

8. A lithium-ion battery, characterized in that, Includes the lithium-ion battery electrolyte as described in any one of claims 1-7.

9. An electrochemical device, characterized in that, Including the lithium-ion battery as described in claim 8.

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