Non-aqueous electrolyte and lithium ion battery

Abstract

In order to solve the problems of high internal resistance, high-temperature gas production and poor high and low temperature capacity retention rate of a lithium ion battery, the invention provides a non-aqueous electrolyte and a lithium ion battery, the non-aqueous electrolyte comprises a lithium salt, an organic solvent and an additive, the additive comprises a succinic anhydride derivative and a fluorinated ester compound, the succinic anhydride derivative is selected from one or more of substances shown in a structural general formula (1) and / or a structural formula (2); the fluoro ester compound is selected from one or more of fluoro boric acid ester II, fluoro carboxylic ester, fluoro chain carbonate IV, fluoro phosphate V and fluoro phosphite VI.

Description

Technical Field

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

[0002] Lithium-ion rechargeable batteries are suitable for use as portable power sources in personal computers and portable terminals, as well as for driving power in electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles. However, the increased oxidation activity and poor stability of the positive electrode material in lithium-ion batteries make it easy for non-aqueous electrolytes to undergo electrochemical oxidation reactions on the positive electrode surface, leading to decomposition and gas generation. Simultaneously, transition metal elements in the positive electrode active material undergo reduction reactions at the negative electrode and dissolve, further deteriorating the electrochemical performance of the lithium-ion battery. For the negative electrode, a stable, low-resistance SEI film needs to be formed at the negative electrode interface by the electrolyte to protect it. Therefore, it is necessary to develop an electrolyte that can form a passivation protective film at both the positive and negative electrodes, effectively reducing the battery's internal resistance, suppressing high-temperature gas generation, and improving the battery's capacity retention rate at both high and low temperatures. Summary of the Invention

[0003] The purpose of this invention is to provide a non-aqueous electrolyte and lithium-ion battery that can effectively reduce the internal resistance of the battery, suppress high-temperature gas generation, and improve the capacity retention rate at high and low temperatures.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] The first aspect of this invention provides a non-aqueous electrolyte, comprising an organic solvent, a lithium salt, and additives, wherein the additives include succinic anhydride derivatives and fluorinated ester compounds; wherein,

[0006] The succinic anhydride derivative is selected from one or more substances as shown in general structural formula (1) and / or structural formula (2);

[0007] The general formula (1) of the structure is: Wherein, R1 and R2 are independently hydrogen, alkyl with 1 to 6 carbon atoms, cycloalkyl with 3 to 8 carbon atoms, and carbonyl with 1 to 6 carbon atoms, and R1 and R2 may be the same or different;

[0008] The structural formula (2) is

[0009] The fluoroester compounds are selected from one or more of the following: fluoroboronic acid ester II, fluorocarboxylic acid ester III, fluorochain carbonate IV, fluorophosphate V, and fluorophosphite VI.

[0010] The structural formula of the fluoroboronate II is as follows:

[0011] The structural formula of the fluorocarboxylic acid ester III is as follows:

[0012] The structural formula of the fluorinated chain carbonate IV is as follows:

[0013] The structural formula of the fluorophosphate V is as follows:

[0014] The structural formula of the fluorophosphite VI is as follows:

[0015] Wherein, R3, R4, R5, R6, R7, R8, and R9 are independently alkyl groups having 1 to 6 carbon atoms or fluoroalkyl groups having 1 to 6 carbon atoms; the three R3s in the fluoroboronate II may be the same or different, and at least one R3 is a fluoroalkyl group having 1 to 6 carbon atoms; at least one of R4 and R5 is a fluoroalkyl group having 1 to 6 carbon atoms; at least one of R6 and R7 is a fluoroalkyl group having 1 to 6 carbon atoms; the three R8s in the fluorophosphate V may be the same or different, and at least one R8 is a fluoroalkyl group having 1 to 6 carbon atoms; the three R9s in the fluorophosphite VI may be the same or different, and at least one R9 is a fluoroalkyl group having 1 to 6 carbon atoms.

[0016] According to some specific embodiments, R1 and R2 are independently hydrogen, a branched or straight-chain alkyl group with 1-4 carbon atoms, a cycloalkyl group with 4-6 carbon atoms, and a carbonyl group with 1-3 carbon atoms.

[0017] According to some specific embodiments, R1 and R2 are independently hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, cyclopentyl, cyclohexyl or formaldehyde.

[0018] According to some specific embodiments, the compound represented by the general structural formula (1) is selected from the following compounds:

[0019]

[0020] According to some more specific embodiments, the succinic anhydride derivative is and / or

[0021] According to some specific embodiments, R3, R4, R5, R6, R7, R8, and R9 are independently alkyl groups having 1 to 4 carbon atoms or fluoroalkyl groups having 1 to 4 carbon atoms.

[0022] According to some specific embodiments, the three R3s in the fluoroboronic ester II are identical and are fluoroalkyl groups with 1 to 4 carbon atoms that are partially or completely fluorinated. Further, R3 is CH2F, CHF2, CF3, CH2CH2F, CH2CHF2, CH2CF3, CH2CH2CH2F, CH2CH2CHF2, CH2CH2CF3, CH(CH2F)2, CH(CHF2)2, or CH(CF3)2.

[0023] According to some specific embodiments, R4 is a fluoroalkyl group with 1 to 4 carbon atoms that is partially or completely fluorinated. Further, R4 is CH2F, CHF2, CF3, CH2CH2F, CH2CHF2, CH2CF3, CH2CH2CH2F, CH2CH2CHF2, CH2CH2CF3, CH(CH2F)2, CH(CHF2)2, or CH(CF3)2.

[0024] According to some specific embodiments, R5 is an alkyl group having 1 to 4 carbon atoms. Further, R5 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl.

[0025] According to some specific embodiments, one of R6 and R7 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl; the other is CH2F, CHF2, CF3, CH2CH2F, CH2CHF2, CH2CF3, CH2CH2CH2F, CH2CH2CHF2, CH2CH2CF3, CH(CH2F)2, CH(CHF2)2 or CH(CF3)2.

[0026] According to some specific embodiments, the three R8s in the fluorophosphate V are identical and are fluoroalkyl groups with 1 to 4 carbon atoms that are partially or completely fluorinated. Further, the R8s are CH2F, CHF2, CF3, CH2CH2F, CH2CHF2, CH2CF3, CH2CH2CH2F, CH2CH2CHF2, CH2CH2CF3, CH(CH2F)2, CH(CHF2)2, or CH(CF3)2.

[0027] According to some specific embodiments, the three R9s in the fluorophosphite VI are identical and are fluoroalkyl groups with 1 to 4 carbon atoms that are partially or completely fluorinated. Further, R8 is CH2F, CHF2, CF3, CH2CH2F, CH2CHF2, CH2CF3, CH2CH2CH2F, CH2CH2CHF2, CH2CH2CF3, CH(CH2F)2, CH(CHF2)2, or CH(CF3)2.

[0028] According to some specific embodiments, the fluorinated ester compound is one or more selected from the following compounds:

[0029]

[0030] According to some more specific embodiments, the fluorinated ester compound is

[0031] According to some specific embodiments, the succinic anhydride derivative accounts for 0.05% to 5% of the total weight of the electrolyte, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc. 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, or 5%. Further, the succinic anhydride derivative constitutes 0.1% to 2% of the total weight of the electrolyte.

[0032] According to some specific embodiments, the fluorinated ester compounds account for 0.05% to 5% of the total weight of the electrolyte, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc. 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, or 5%. Further, the fluorinated ester compound accounts for 0.1% to 1% of the total weight of the electrolyte.

[0033] According to some specific embodiments, the organic solvent includes one or more of substituted or unsubstituted carbonates, substituted or unsubstituted carboxylic esters, substituted or unsubstituted ethers, substituted or unsubstituted sulfones, substituted or unsubstituted sulfoxides, and substituted or unsubstituted benzenes.

[0034] Further, the organic solvent is a mixture of two or more of the following: fluoroethylene carbonate, difluoroethylene carbonate, fluoroethyl sulfone, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, sulfolane, methyl ethyl sulfone, dimethyl sulfoxide, and fluorobenzene.

[0035] According to some specific embodiments, the organic solvent accounts for 60% to 90% of the total weight of the electrolyte, for example, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. Further, the organic solvent accounts for 70% to 85% of the total weight of the electrolyte.

[0036] In some more specific embodiments, the organic solvent is a combination of ethylene carbonate, diethyl carbonate, propylene carbonate, and methyl ethyl carbonate. Further, the mass ratio of ethylene carbonate, diethyl carbonate, propylene carbonate, and methyl ethyl carbonate is 2–3:1–2:1:5–5.5.

[0037] According to some specific embodiments, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluoroborate oxalate, lithium difluorooxalate phosphate, lithium tetrafluorooxalate phosphate, lithium fluorosulfonate, and lithium 4,5-dicyano-2-trifluoromethylimidazolium.

[0038] According to some specific embodiments, the lithium salt accounts for 8% to 30% of the total weight of the electrolyte, for example, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%. Further, the lithium salt accounts for 10% to 20% of the total weight of the electrolyte.

[0039] In some more specific embodiments, the lithium salt is a combination of LiPF6, LiDFP, and LiFSI. Further, the mass ratio of LiPF6, LiDFP, and LiFSI is 25–30:1:2–6.

[0040] According to some specific embodiments, the additive also includes other additives selected from one or more of the following: cyclic carbonates containing double bonds, halogenated cyclic carbonates, sulopentalides, sulfonates, sulfates, sulfites, benzene compounds, fluorobenzene compounds, nitrile compounds, boron compounds, phosphorus compounds, amine compounds, silicon-containing compounds, and heterocyclic compounds.

[0041] Further, the other additives include vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, vinyl sulfate, propylene sulfate, methanedisulfonate, vinyl sulfite, 1,3-propanesulfonate lactone, biphenyl, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, m-fluorotoluene, 3,4-difluorotoluene, p-fluorotoluene, p-xylene, 1,2-dimethoxy-4-nitrobenzene, N-phenylmaleimide, pentafluoroanisole, 2,5-di-tert-butyl, 1,4-difluorobenzene, etc. -One or more of the following: dimethoxybenzene, adiponitrile, hexanetrionitrile, butadionitrile, 1,2,3-tris(2-cyanoethoxy)propane, N,N-dicyclohexylcarbodiimide, N,N-diethylaminetrimethylsilane, hexamethyldisilazane, tris(trimethylsilane)phosphate, tris(trimethylsilane)borate, triallyl isocyanurate, triphenyl phosphate, heptanonitrile, 2-ethoxy-2,4,4,6,6-pentafluorotriphosphazene, 2-fluoropyridine, and 1,3-dioxane.

[0042] Further, the other additives account for 0.3% to 10% of the total weight of the electrolyte. Even further, the other additives account for 0.5% to 8% of the total weight of the electrolyte.

[0043] A second aspect of the present invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the aforementioned electrolyte.

[0044] According to some specific embodiments, the active material of the positive electrode is selected from LiNi. x Co y M z O2 (where M can be metals such as Mn and Al, the value of x is 0-1, the value of y is 0-1, and the value of z is 0-1), lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), lithium manganese iron phosphate (LiMn a Fe 1-a PO4, where the value of a is 0 to 1) at least one of them.

[0045] According to some specific embodiments, the active material of the negative electrode is graphite and / or silicon, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, or spinel-structured lithiated TiO2-Li4Ti5O. 12 Li-Al alloys, etc., wherein the graphite and / or silicon are, for example, natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites.

[0046] According to some specific embodiments, the lithium-ion battery includes a casing, a battery cell housed within the casing, and a non-aqueous electrolyte. The battery cell includes a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. The separator can be any separator conventionally used in the art, and this invention does not impose specific limitations.

[0047] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0048] This invention improves the film formation effect of the negative electrode by combining a succinic anhydride derivative with a specific structure and a fluorinated ester compound with a specific structure, solves the problems of increased internal resistance and high-temperature gas generation in lithium-ion batteries, and improves the capacity retention rate of lithium-ion batteries at high and low temperatures. Detailed Implementation

[0049] To address the existing problems of increased internal resistance, high-temperature gas generation, and poor capacity retention at high and low temperatures in lithium-ion batteries, the inventors conducted in-depth research and numerous experiments, resulting in this solution, which will be further discussed below.

[0050] This invention improves the film formation effect of the negative electrode by using a combination of succinic anhydride derivatives as shown in general structural formula (1) and / or structural formula (2) and fluorinated ester compounds, wherein the fluorinated ester compounds are selected from one or more of fluoroboronic acid ester II, fluorocarboxylic acid ester III, fluorochain carbonate IV, fluorophosphate V, and fluorophosphite VI. This solves the problems of increased internal resistance and high-temperature gas generation in lithium-ion batteries and improves the capacity retention rate of lithium-ion batteries at high and low temperatures.

[0051] in,

[0052] The general formula (1) of the structure is: Wherein, R1 and R2 are independently hydrogen, alkyl with 1 to 6 carbon atoms, cycloalkyl with 3 to 8 carbon atoms, and carbonyl with 1 to 6 carbon atoms, and R1 and R2 may be the same or different;

[0053] The structural formula (2) is

[0054] The structural formula of the fluoroboronate II is as follows:

[0055] The structural formula of the fluorocarboxylic acid ester III is as follows:

[0056] The structural formula of the fluorinated chain carbonate IV is as follows:

[0057] The structural formula of the fluorophosphate V is as follows:

[0058] The structural formula of the fluorophosphite VI is as follows:

[0059] Wherein, R3, R4, R5, R6, R7, R8, and R9 are independently alkyl groups having 1 to 6 carbon atoms or fluoroalkyl groups having 1 to 6 carbon atoms; the three R3s in the fluoroboronate II may be the same or different, and at least one R3 is a fluoroalkyl group having 1 to 6 carbon atoms; at least one of R4 and R5 is a fluoroalkyl group having 1 to 6 carbon atoms; at least one of R6 and R7 is a fluoroalkyl group having 1 to 6 carbon atoms; the three R8s in the fluorophosphate V may be the same or different, and at least one R8 is a fluoroalkyl group having 1 to 6 carbon atoms; the three R9s in the fluorophosphite VI may be the same or different, and at least one R9 is a fluoroalkyl group having 1 to 6 carbon atoms.

[0060] Furthermore, the succinic anhydride derivative is selected from... One or more of the following. The fluoroester compound is selected from one or more of the following compounds:

[0061]

[0062] This invention utilizes the low reduction potential of succinic anhydride derivatives with specific structures to form a stable protective film on the negative electrode. Furthermore, it leverages their sulfur-containing cyclic groups to form a protective film on the positive electrode through oxidation. The invention also incorporates fluorinated ester compounds, which selectively decompose during the first battery cycle to modify the negative electrode, thereby optimizing the electrode surface composition and further improving its stability. The use of the electrolyte effectively reduces the battery's internal resistance, suppresses high-temperature gas generation, and improves high-temperature and low-temperature capacity retention.

[0063] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0064] Unless otherwise specified, the reagents, instruments, etc. used in the following examples and comparative examples are all commercially available products commonly used in the art, or can be prepared by conventional preparation methods in the art.

[0065] The abbreviations for the substances in this article are as follows:

[0066] Ethylene carbonate: EC, diethyl carbonate: DEC, methyl ethyl carbonate: EMC, propylene carbonate: PC, fluoroethylene carbonate: FEC, lithium difluorosulfonyl imide: LiFSI, lithium difluorophosphate: LiDFP, 1,3-propanesulfonyl lactone: PS, lithium hexafluorophosphate: LiPF6, ethylene sulfate: DTD.

[0067] SA1: SA2: SA3: SA4: SA5: SA6: Compound II: Compound III Compound IV Compound V: Compound VI:

[0068] Electrolyte preparation:

[0069] The battery electrolytes for each embodiment and comparative example were prepared in a glove box according to the formulations described in Table 1.

[0070] Table 1

[0071]

[0072]

[0073]

[0074]

[0075]

[0076] Experimental test content:

[0077] The electrolytes obtained in the examples and comparative examples were injected into the same batch of 1.2 Ah LiNi. 0.92 Co 0.04 Mn 0.04 In the O2|| artificial graphite polymer pouch battery, the following tests were performed respectively:

[0078] 1) After a fully charged 4.2V battery is left at 70℃ for 28 days, its thickness and internal resistance are tested to obtain the thickness swelling rate H% ((thickness after storage - thickness before storage) / thickness before storage * 100)) and the internal resistance growth rate A% ((internal resistance after storage - internal resistance before storage) / internal resistance before storage * 100).

[0079] 2) After the battery is charged to 4.2V at 1C constant current and constant voltage at 45℃, it is discharged to 2.75V at 1C constant current and cycled for 500 cycles to obtain the capacity retention rate Q1% (500-cycle discharge capacity / average discharge capacity of the first 10 cycles).

[0080] 3) After the battery is charged to 4.2V at 0℃ using 1C constant current and constant voltage, it is then discharged to 2.75V using 1C constant current. After 500 cycles, the capacity retention rate Q2% (500-cycle discharge capacity / average discharge capacity of the first 10 cycles) is obtained.

[0081] The experimental results are shown in Table 2.

[0082] Table 2

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] As shown in Table 2, in 1.2 Ah LiNi 0.92 Co 0.04 Mn 0.04 In artificial graphite polymer soft-pack batteries, the addition of succinic anhydride derivatives and fluorinated ester compounds with specific structures can improve the film formation effect of the negative electrode and solve the problems of increased internal resistance, high-temperature gas generation, and poor capacity retention at high and low temperatures in lithium-ion batteries.

[0089] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be included within the scope of protection of the invention.

Claims

1. A non-aqueous electrolyte, comprising an organic solvent, a lithium salt, and an additive, characterized in that: The additives include succinic anhydride derivatives and fluorinated ester compounds; wherein... The succinic anhydride derivative is selected from one or more substances as shown in general structural formula (1) and / or structural formula (2); The general formula (1) of the structure is: Wherein, R1 and R2 are independently hydrogen, alkyl with 1 to 6 carbon atoms, cycloalkyl with 3 to 8 carbon atoms, and carbonyl with 1 to 6 carbon atoms, and R1 and R2 may be the same or different; The structural formula (2) is The fluoroester compounds are selected from one or more of the following: fluoroboronic acid ester II, fluorocarboxylic acid ester III, fluorochain carbonate IV, fluorophosphate V, and fluorophosphite VI. The structural formula of the fluoroboronate II is as follows: The structural formula of the fluorocarboxylic acid ester III is as follows: The structural formula of the fluorinated chain carbonate IV is as follows: The structural formula of the fluorophosphate V is as follows: The structural formula of the fluorophosphite VI is as follows: Wherein, R3, R4, R5, R6, R7, R8, and R9 are independently alkyl groups having 1 to 6 carbon atoms or fluoroalkyl groups having 1 to 6 carbon atoms; the three R3s in the fluoroboronate II may be the same or different, and at least one R3 is a fluoroalkyl group having 1 to 6 carbon atoms; at least one of R4 and R5 is a fluoroalkyl group having 1 to 6 carbon atoms; at least one of R6 and R7 is a fluoroalkyl group having 1 to 6 carbon atoms; the three R8s in the fluorophosphate V may be the same or different, and at least one R8 is a fluoroalkyl group having 1 to 6 carbon atoms; the three R9s in the fluorophosphite VI may be the same or different, and at least one R9 is a fluoroalkyl group having 1 to 6 carbon atoms.

2. The non-aqueous electrolyte according to claim 1, characterized in that: R1 and R2 are independently hydrogen, a branched or straight-chain alkyl group with 1 to 4 carbon atoms, a cycloalkyl group with 4 to 6 carbon atoms, and a carbonyl group with 1 to 3 carbon atoms.

3. The non-aqueous electrolyte according to claim 2, characterized in that: The compounds represented by general structural formula (1) are selected from the following compounds:

4. The non-aqueous electrolyte according to claim 1, characterized in that: R3, R4, R5, R6, R7, R8, and R9 are independently alkyl groups having 1 to 4 carbon atoms, or fluoroalkyl groups having 1 to 4 carbon atoms.

5. The non-aqueous electrolyte according to claim 4, characterized in that: The fluorinated ester compound is selected from one or more of the following compounds:

6. The non-aqueous electrolyte according to any one of claims 1 to 5, characterized in that: The succinic anhydride derivative accounts for 0.05% to 5% of the total weight of the electrolyte, and the fluorinated ester compound accounts for 0.05% to 5% of the total weight of the electrolyte.

7. The non-aqueous electrolyte according to claim 6, characterized in that: The succinic anhydride derivative accounts for 0.1% to 2% of the total weight of the electrolyte, and the fluorinated ester compound accounts for 0.1% to 1% of the total weight of the electrolyte.

8. The non-aqueous electrolyte according to claim 1, characterized in that: The organic solvent includes one or more of substituted or unsubstituted carbonates, substituted or unsubstituted carboxylic esters, substituted or unsubstituted ethers, substituted or unsubstituted sulfones, substituted or unsubstituted sulfoxides, and substituted or unsubstituted benzenes; the organic solvent accounts for 60% to 90% of the total weight of the electrolyte; The lithium salt comprises one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluoroborate oxalate, lithium difluorooxalate phosphate, lithium tetrafluorooxalate phosphate, lithium fluorosulfonate, and lithium 4,5-dicyano-2-trifluoromethylimidazolium, and the lithium salt accounts for 8% to 30% of the total weight of the electrolyte.

9. The non-aqueous electrolyte according to claim 8, characterized in that: The organic solvent is a mixture of two or more of the following: fluoroethylene carbonate, difluoroethylene carbonate, fluoroethyl sulfone, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, sulfolane, methyl ethyl sulfone, dimethyl sulfoxide, and fluorobenzene; the organic solvent accounts for 70% to 85% of the total weight of the electrolyte. The lithium salt accounts for 10% to 20% of the total weight of the electrolyte.

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

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