Non-aqueous electrolyte and lithium secondary battery

Abstract

The invention relates to a non-aqueous electrolyte and a lithium secondary battery. In order to solve the problem that a lithium secondary battery cannot give consideration to high and low temperature circulation and rate capability, a first additive, a second additive and a third additive are added into an electrolyte, the first additive is # imgabs0; the second additive is selected from one or more of a fluoro boric acid ester compound, a fluoro carboxylic acid ester compound, a fluoro chain carbonate ester compound, a fluoro phosphate ester compound, a fluoro phosphite ester compound and a fluoro chain sulfonate ester compound; the third additive is selected from one or more of double-bond-containing cyclic carbonate, halogen-containing cyclic carbonate, cyclic sulfonate, sulfate, sulfite, anhydride, a benzene compound, a nitrile compound, halogen-free phosphate, halogen-free phosphite, a halogen-free boron compound, an amine compound, a silicon-containing compound and a six-membered heterocyclic compound; through the synergistic effect of the three additives, the cycle performance and the rate performance of the lithium secondary battery at high and low temperatures are improved.

Description

Technical Field

[0001] The invention relates to a non-aqueous electrolyte and a lithium secondary battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, low self-discharge, no memory effect, wide operating voltage range, long service life, and no environmental pollution. They are widely used in portable electronic devices and are also promoted in fields such as electric vehicles. With the expansion of lithium-ion battery applications and the development of modern information technology, lithium-ion batteries are facing higher challenges, and it is necessary to further improve the high and low temperature cycle and rate performance of lithium-ion batteries.

[0003] As an important carrier of ion transmission in lithium-ion batteries, the composition and performance of electrolytes will greatly affect battery performance. The lithium-ion electrolytes currently used cannot take into account both high and low temperature and rate performance, which limits the application of lithium-ion batteries to a certain extent. Therefore, it is of great significance to develop electrolytes and lithium-ion batteries that can have both high and low temperature and rate performance. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a non-aqueous electrolyte and a lithium secondary battery capable of improving the cycle and rate performance of the battery at high and low temperatures.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A non-aqueous electrolyte comprises an organic solvent, a lithium salt and an additive, wherein the additive comprises a first additive, a second additive and a third additive, wherein the first additive is selected from one or more compounds represented by formula I, wherein formula I is Among them, R 1 , R 2 , R 3 , R 4 are independently selected from hydrogen, alkyl, haloalkyl, cyano, halo, -COCN, -COR 0 , alkenyl, haloalkenyl, alkynyl or haloalkynyl, and R 1 , R 2 , R 3 , R 4 At least one of them is cyano or -COCN, R 0 Selected from alkyl;

[0007] The second additive is selected from one or more of fluorinated borate compounds, fluorinated carboxylate compounds, fluorinated chain carbonate compounds, fluorinated phosphate compounds, fluorinated phosphite compounds and fluorinated chain sulfonate compounds.

[0008] The structural formula of the fluoroboric acid ester compound is: R 5 A fluoroalkyl group having 1 to 6 carbon atoms;

[0009] The structural formula of the fluorocarboxylate compound is: R 6 is selected from an alkyl group having 1 to 6 carbon atoms, R 7 A fluoroalkyl group having 1 to 6 carbon atoms;

[0010] The structural formula of the fluorinated chain carbonate compound is: R 8 is selected from fluoroalkyl groups having 1 to 6 carbon atoms, R 9 is selected from an alkyl group having 1 to 6 carbon atoms;

[0011] The structural formula of the fluorophosphate compound is: R 10 A fluoroalkyl group having 1 to 6 carbon atoms;

[0012] The structural formula of the fluorophosphite compound is: R 11 A fluoroalkyl group having 1 to 6 carbon atoms;

[0013] The structural formula of the fluorinated chain sulfonate compound is: R 12 is selected from an alkyl group having 1 to 6 carbon atoms, R 13 A fluoroalkyl group having 1 to 6 carbon atoms;

[0014] The third additive is selected from one or more of cyclic carbonates containing double bonds, cyclic carbonates containing halogens, cyclic sulfonates, sulfates, sulfites, acid anhydrides, benzene compounds, nitrile compounds, halogen-free phosphates, halogen-free phosphites, halogen-free boron compounds, amine compounds, silicon-containing compounds, and six-membered heterocyclic compounds.

[0015] The sulfur-containing heterocyclic compound shown in the first additive can form a uniform and thin CEI (positive electrode electrolyte interface) and SEI (solid electrolyte interface) between the electrolyte and the electrode, protecting the material from HF corrosion. The fluorination agent shown in the second additive can improve the electrolyte interface chemistry, facilitate rapid interface ion transport at high and low temperatures, provide more inorganic SEI components before the solvent decomposes, and form an interface layer rich in LiF or F-containing complexes, thereby providing high interface chemistry and mechanical stability; at the same time, the unique Li in the fluorination agent with low solvation ability +-The anion solvation structure is also conducive to the formation of LiF, which helps to form a dense and well-passivated interface layer, allowing uniform ion flux and reducing interface resistance. The present invention improves the high and low temperature cycle and rate performance of the lithium secondary battery through the synergistic effect of multiple additives, especially the first additive and the second additive.

[0016] Preferably, the R 1 is selected from an alkyl group having 1 to 3 carbon atoms or a cyano group, wherein R 2 is selected from hydrogen or cyano, said R 3 is selected from hydrogen or halogen, said R 4 Selected from hydrogen, -COCN, -COR 0 or an alkyl group having 1 to 3 carbon atoms, wherein R 0 The halogen group is selected from an alkyl group having 2 to 4 carbon atoms, and the halogen group is fluorine.

[0017] According to the present invention, the alkyl group with 1 carbon atom is methyl, the alkyl group with 2 carbon atoms is ethyl, the alkyl group with 3 carbon atoms is n-propyl or isopropyl, and the alkyl group with 4 carbon atoms is n-butyl, isobutyl, sec-butyl or tert-butyl.

[0018] In some specific embodiments, the first additive is selected from

[0019] One or more of .

[0020] Preferably, the first additive accounts for 0.05% to 5% of the total weight of the non-aqueous electrolyte.

[0021] Further preferably, the first additive accounts for 0.5% to 2% of the total weight of the non-aqueous electrolyte, for example 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8% or 2%.

[0022] Preferably, the R 5 , R 7 , R 8 , R 10 , R 11 , R 13 are independently selected from fluoroalkyl groups having 1 to 4 carbon atoms, wherein R 6 , R 9 , R 12 Each is independently selected from an alkyl group having 1 to 2 carbon atoms.

[0023] More preferably, the R 5 , R 7 , R 8 , R 10 , R 11 , R13 Each is independently selected from a fluorinated alkyl group having 2 to 3 carbon atoms.

[0024] According to the present invention, the fluoroalkyl group having 1 to 4 or 2 to 3 carbon atoms may be a group in which only part of the hydrogen atoms in the alkyl group are replaced by fluorine atoms, or all of the hydrogen atoms in the alkyl group are replaced by fluorine atoms. 2 CHF 2 or -CH 2 CF 3 , the fluoroalkyl group with 3 carbon atoms is -CH 2 (CF 3 ) 2 .

[0025] In some specific embodiments, the fluoroborate compound is

[0026] In some specific embodiments, the fluorocarboxylate compound is

[0027] In some specific embodiments, the fluorinated chain carbonate compound is

[0028] In some specific embodiments, the fluorophosphate compound is

[0029] In some specific embodiments, the fluorophosphite compound is

[0030] In some specific embodiments, the fluorinated chain sulfonate compound is

[0031] Preferably, the second additive accounts for 0.05% to 5% of the total weight of the non-aqueous electrolyte.

[0032] Further preferably, the second additive accounts for 0.5% to 2% of the total weight of the non-aqueous electrolyte, for example 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8% or 2%.

[0033] Preferably, the third additive is selected from vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, vinyl sulfate, methylene methanedisulfonate, vinyl sulfite, 1,3-propane sultone, biphenyl, succinic anhydride, glutaric anhydride, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, m-fluorotoluene, 3,4-difluorotoluene, 4-bromo-2-fluoroanisole, p-fluorotoluene, p-xylene, 1,2-dimethoxy-4-nitrobenzene, N-phenylbenzene, One or more of imide, pentafluoroanisole, 1,4-dimethoxybenzene, adiponitrile, hexanetrinitrile, succinonitrile, 1,2,3-tris(2-cyanoethoxy)propane, n-butylamine, ethanolamine, N,N-dicyclohexylcarbodiimide, N,N-diethylaminotrimethylsilane, hexamethyldisilazane, triphenyl phosphate, pimelonitrile, 2-ethoxy-2,4,4,6,6-pentafluorotripolyphosphazene, 2-fluoropyridine, and 1,3-dioxane.

[0034] Preferably, the third additive accounts for 0.3% to 10% of the total weight of the non-aqueous electrolyte.

[0035] Further preferably, the third additive accounts for 1% to 5% of the total weight of the non-aqueous electrolyte, for example, 1%, 2%, 3%, 4% or 5%.

[0036] In some preferred embodiments, the third additive is vinylene carbonate and vinyl sulfate.

[0037] Furthermore, the mass ratio of vinylene carbonate to vinyl sulfate is 1:(0.5-1.5), for example, 1:0.5, 1:0.8, 1:1, 1:1.3, 1:1.5, etc.

[0038] Preferably, the organic solvent comprises one or more of substituted or unsubstituted carbonate, substituted or unsubstituted carboxylate, substituted or unsubstituted ether, substituted or unsubstituted sulfone, substituted or unsubstituted sulfoxide, substituted or unsubstituted benzene, and the substituted group comprises a fluorine atom.

[0039] Further preferably, the organic solvent is selected from two or more of fluoroethylene carbonate, difluoroethylene carbonate, fluoroethyl sulfone, tetrafluoroethyl tetrafluoropropyl ether, trifluoroethyl hexafluoropropyl ether, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, ethylene glycol dimethyl ether, r-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, cyclopentane, methyl ethyl sulfone, dimethyl sulfoxide, and fluorobenzene.

[0040] In some specific embodiments, the organic solvent is ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate and propylene carbonate.

[0041] Furthermore, the mass ratio of ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate and propylene carbonate is 1: (0.2-0.7): (1.5-2.5): (0.1-0.4): (0.1-0.4), and further 1: (0.4-0.6): (1.9-2.1): (0.2-0.3): (0.2-0.3).

[0042] Preferably, the organic solvent accounts for 60% to 90% of the total weight of the non-aqueous electrolyte.

[0043] Further preferably, the organic solvent accounts for 70% to 85% of the total weight of the non-aqueous electrolyte, for example 70%, 73%, 75%, 78%, 80%, 83% or 85%.

[0044] Preferably, the lithium salt includes a first lithium salt and a second lithium salt, the first lithium salt is lithium hexafluorophosphate, and the second lithium salt is selected from one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate, lithium dioxalatoborate, lithium oxalatodifluoroborate, lithium difluorooxalatophosphate, lithium tetrafluorooxalatophosphate, lithium fluorosulfonate and lithium 4,5-dicyano-2-trifluoromethylimidazole.

[0045] Preferably, the lithium salt accounts for 8% to 30% of the total weight of the non-aqueous electrolyte.

[0046] Further preferably, the lithium salt accounts for 10% to 20% of the total weight of the non-aqueous electrolyte, for example 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0047] In some embodiments, the first lithium salt accounts for 10% to 15% of the total weight of the non-aqueous electrolyte, and the second lithium salt accounts for 1% to 5% of the total weight of the non-aqueous electrolyte.

[0048] In some specific embodiments, the second lithium salt is lithium bis(fluorosulfonyl)imide and lithium difluorophosphate.

[0049] Furthermore, lithium bis(fluorosulfonyl)imide accounts for 2% to 3% of the total weight of the non-aqueous electrolyte, and lithium difluorophosphate accounts for 0.5% to 1.5% of the total weight of the non-aqueous electrolyte.

[0050] A second object of the present invention is to provide a lithium secondary battery comprising a positive electrode, a negative electrode and a separator disposed between the positive electrode and the negative electrode, wherein the lithium secondary battery further comprises the non-aqueous electrolyte as described above.

[0051] Preferably, the positive electrode active material in the positive electrode is LiNi x Co y Mn z O2 or LiNi x Co y Al z O 2 , wherein the value of x is 0 to 1, further 0.5 to 1, the value of y is 0 to 1, further (0.01 to 0.2), and the value of z is 0 to 1, further 0.01 to 0.2); the negative electrode active material in the negative electrode includes metallic lithium, metal oxides, lithium aluminum alloys, graphite, modified carbon materials, silicon, silicon oxygen or silicon oxygen carbon.

[0052] According to the present invention, the positive electrode includes a positive electrode collector and a positive electrode material located on the surface of the positive electrode collector. The positive electrode material includes a positive electrode active substance, a positive electrode conductor and a positive electrode binder. The positive electrode conductor may be, for example, acetylene black or carbon nanotubes, and the positive electrode binder may be, for example, polyvinylidene fluoride.

[0053] According to the present invention, the negative electrode includes a negative electrode current collector and a negative electrode material located on the surface of the negative electrode current collector. The negative electrode material includes a negative electrode active substance and a negative electrode binder. The negative electrode material may also selectively include a negative electrode conductive agent. The negative electrode conductive agent may be the same as or different from the positive electrode conductive agent, and both are conductive agents commonly used in the art. The negative electrode binder is a negative electrode binder conventionally used in the art, and the present invention does not impose any specific limitation.

[0054] According to the present invention, the separator may be a separator conventionally used in the art, and the present invention is not particularly limited thereto.

[0055] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0056] The present invention improves the high and low temperature cycle and rate performance of the lithium secondary battery through the synergistic effect of the first additive, the second additive and the third additive. DETAILED DESCRIPTION

[0057] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0058] Preparation of electrolyte:

[0059] The specific embodiments and comparative examples of the present invention are prepared in a glove box according to the formulas described in Table 1 and Table 2. The substances involved in the table are ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate (PC), fluoroethylene carbonate (FEC), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorophosphate (LiDFP), vinylene carbonate (VC), vinyl sulfate (DTD), lithium hexafluorophosphate (LiPF 6 );

[0060] The structural formula of A1 is: The structural formula of A2 is:

[0061] The structural formula of A3 is: The structural formula of A4 is: The structural formula of A5 is: Fluoroborate ester structural formula is: Fluorinated carboxylic acid ester structural formula is: The structural formula of fluorinated chain carbonate is: Fluorinated phosphate structural formula is: Fluorophosphite structural formula is: The structural formula of fluorinated chain sulfonate is:

[0062] Table 1

[0063]

[0064]

[0065]

[0066] The wt% in Table 1 is a unit of weight percentage, which indicates weight ratio, that is, the proportion of one substance in the mixture.

[0067] Preparation of the battery:

[0068] The electrolytes obtained in Examples 1 to 36 and Comparative Examples 1 to 11 were injected into 1Ah LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) || Silicon oxygen carbon (420mAh) polymer soft pack battery, the following tests were carried out:

[0069] (1) The test battery is charged and discharged for 500 cycles at 0°C, 25°C and 45°C, with a voltage between 2.75-4.2V and a current of 1C. The capacity retention rates are L1%, L2 and L3% (discharge capacity after 500 cycles / average discharge capacity before 5 weeks × 100%).

[0070] (2) When the battery is tested at 25°C, voltage between 2.75-4.2V, and current of 5C, the capacity retention rate of the battery after 150 charge and discharge cycles is L4% (discharge capacity after 150 cycles / average discharge capacity before 5 weeks × 100%).

[0071] The above experimental results are shown in Table 2.

[0072] Table 2

[0073]

[0074]

[0075] Table 2 shows that in LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)||Silicon Oxycarbon (420mAh) In the 1Ah polymer soft-pack battery, the combination of the first additive, the second additive and the third additive can further improve the battery's high and low temperature cycle and rate charge and discharge problems.

[0076] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them, but it does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-aqueous electrolyte comprising an organic solvent, a lithium salt and an additive, characterized in that: The additives include a first additive, a second additive and a third additive, wherein the first additive is selected from one or more compounds represented by formula I, wherein formula I is wherein R1, R2, R3, and R4 are independently selected from hydrogen, alkyl, haloalkyl, cyano, halo, -COCN, -COR0, alkenyl, haloalkenyl, alkynyl, or haloalkynyl, and at least one of R1, R2, R3, and R4 is cyano or -COCN, and R0 is selected from alkyl; The second additive is selected from one or more of fluorinated borate compounds, fluorinated carboxylate compounds, fluorinated chain carbonate compounds, fluorinated phosphate compounds, fluorinated phosphite compounds and fluorinated chain sulfonate compounds. The structural formula of the fluoroboric acid ester compound is: R5 is selected from a fluorinated alkyl group having 1 to 6 carbon atoms; The structural formula of the fluorocarboxylate compound is: R6 is selected from an alkyl group having 1 to 6 carbon atoms, and R7 is selected from a fluoroalkyl group having 1 to 6 carbon atoms; The structural formula of the fluorinated chain carbonate compound is: R8 is selected from a fluorinated alkyl group having 1 to 6 carbon atoms, and R9 is selected from an alkyl group having 1 to 6 carbon atoms; The structural formula of the fluorophosphate compound is: R 10 A fluoroalkyl group having 1 to 6 carbon atoms; The structural formula of the fluorophosphite compound is: R 11 A fluoroalkyl group having 1 to 6 carbon atoms; The structural formula of the fluorinated chain sulfonate compound is: R 12 is selected from an alkyl group having 1 to 6 carbon atoms, R 13 A fluoroalkyl group having 1 to 6 carbon atoms; The third additive is selected from one or more of cyclic carbonates containing double bonds, cyclic carbonates containing halogens, cyclic sulfonates, sulfates, sulfites, acid anhydrides, benzene compounds, nitrile compounds, halogen-free phosphates, halogen-free phosphites, halogen-free boron compounds, amine compounds, silicon-containing compounds, and six-membered heterocyclic compounds.

2. The non-aqueous electrolyte according to claim 1, characterized in that: The R1 is selected from an alkyl group having 1 to 3 carbon atoms or a cyano group, the R2 is selected from hydrogen or a cyano group, the R3 is selected from hydrogen or a halogen group, the R4 is selected from hydrogen, -COCN, -COR0 or an alkyl group having 1 to 3 carbon atoms, the R0 is selected from an alkyl group having 2 to 4 carbon atoms, and the halogen group is fluorine; and / or the first additive accounts for 0.05% to 5% of the total weight of the non-aqueous electrolyte.

3. The non-aqueous electrolyte according to claim 2, characterized in that: The first additive of the formula is selected from One or more of; and / or, The first additive accounts for 0.5% to 2% of the total weight of the non-aqueous electrolyte.

4. The non-aqueous electrolyte according to claim 1, characterized in that: R5, R7, R8, R 10 , R 11 , R 13 are independently selected from fluoroalkyl groups having 1 to 4 carbon atoms, wherein R6, R9, R 12 are independently selected from alkyl groups having 1 to 2 carbon atoms; and / or, The second additive accounts for 0.05% to 5% of the total weight of the non-aqueous electrolyte.

5. The non-aqueous electrolyte according to claim 4, characterized in that: The fluoroboric acid ester compound is and / or, The fluorocarboxylate compound is and / or, The fluorinated chain carbonate compound is and / or, The fluorophosphate compound is and / or, The fluorophosphite compound is And / or, the fluorinated chain sulfonate compound is and / or, The second additive accounts for 0.5% to 2% of the total weight of the non-aqueous electrolyte.

6. The non-aqueous electrolyte according to claim 1, characterized in that: The third additive is selected from vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, vinyl sulfate, methylene methanedisulfonate, vinyl sulfite, 1,3-propane sultone, biphenyl, succinic anhydride, glutaric anhydride, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, m-fluorotoluene, 3,4-difluorotoluene, 4-bromo-2-fluoroanisole, p-fluorotoluene, p-xylene, 1,2-dimethoxy-4-nitrobenzene, N-phenylmaleimide, pentafluoroanisole, 1,4-dimethoxybenzene, adiponitrile, hexanetrinitrile, succinonitrile, 1,2,3-tris(2-cyanoethoxy)propane, n-butylamine, ethanolamine, N,N-dicyclohexylcarbodiimide, N,N-diethylaminotrimethylsilane, hexamethyldisilazane, triphenyl phosphate, pimelonitrile, 2-ethoxy-2,4,4,6,6-pentafluorotriphosphazene, 2-fluoropyridine, 1, One or more of 3-dioxane; and / or, The third additive accounts for 0.3% to 10% of the total weight of the non-aqueous electrolyte.

7. 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 carboxylates, substituted or unsubstituted ethers, substituted or unsubstituted sulfones, substituted or unsubstituted sulfoxides, and substituted or unsubstituted benzenes, and the substituted groups include fluorine atoms; and / or the organic solvent accounts for 60% to 90% of the total weight of the non-aqueous electrolyte.

8. The non-aqueous electrolyte according to claim 7, characterized in that: The organic solvent is selected from two or more of fluoroethylene carbonate, difluoroethylene carbonate, fluoroethyl sulfone, tetrafluoroethyl tetrafluoropropyl ether, trifluoroethyl hexafluoropropyl ether, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, r-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, cyclopentane, methyl ethyl sulfone, dimethyl sulfoxide, and fluorobenzene; and / or, The organic solvent accounts for 70% to 85% of the total weight of the non-aqueous electrolyte.

9. The non-aqueous electrolyte according to claim 1, characterized in that: The lithium salt comprises a first lithium salt and a second lithium salt, wherein the first lithium salt is lithium hexafluorophosphate, and the second lithium salt is selected from one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate, lithium dioxalatoborate, lithium oxalatodifluoroborate, lithium difluorooxalatophosphate, lithium tetrafluorooxalatophosphate, lithium fluorosulfonate and lithium 4,5-dicyano-2-trifluoromethylimidazole; and / or, The lithium salt accounts for 8% to 30% of the total weight of the non-aqueous electrolyte.

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

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