Compound for electrolyte solution, compound for electrolyte solution additive, electrolyte solution material, electrolyte solution additive, electrolyte solution for secondary battery, and secondary battery

Abstract

The present invention relates to a compound for an electrolyte solution, a compound for an electrolyte solution additive, an electrolyte solution substance, an electrolyte solution additive, an electrolyte solution for a secondary battery, and a secondary battery, and provides an electrolyte solution for a secondary battery comprising a novel compound or an isomer thereof.

Description

Technical Field

[0001] This invention relates to a compound for electrolytes, a compound for electrolyte additives, an electrolyte substance, an electrolyte additive, an electrolyte for secondary batteries, and a secondary battery. Background Technology

[0002] Lithium-ion batteries are used as power sources for portable electronic devices such as cameras, mobile phones, and laptops. Compared to existing lead-acid, nickel-cadmium, nickel-metal hydride, and nickel-zinc batteries, rechargeable lithium-ion batteries have more than three times the energy density per unit weight and can be charged at high speeds.

[0003] Because lithium-ion batteries operate at high driving voltages, aqueous electrolytes, which are highly reactive with lithium, cannot be used. Organic electrolytes are commonly used as electrolytes for lithium-ion batteries. Organic electrolytes are prepared by dissolving lithium salts in organic solvents. Organic solvents tend to be stable at high voltages and, preferably, have high ionic conductivity, high dielectric constant, and low viscosity.

[0004] On the other hand, depending on which materials are used as the negative electrode, positive electrode, and electrolyte, the battery's voltage, lifespan, capacity, and stability can vary significantly. Therefore, there is a need for an electrolyte for lithium-ion secondary batteries that can provide lithium-ion secondary batteries with improved lifespan characteristics and high-temperature stability. Summary of the Invention

[0005] Technical issues One object of the present invention is to provide an electrolyte for secondary batteries comprising a novel compound or its isomers.

[0006] Another object of the present invention is to provide a secondary battery comprising the electrolyte for a secondary battery.

[0007] Technical solution To achieve the aforementioned objective, one embodiment of the present invention provides an electrolyte for secondary batteries containing additives.

[0008] A secondary battery electrolyte, the secondary battery electrolyte comprising: An electrolyte for a secondary battery, comprising: (A) a first additive represented by the following chemical formula 1; and (B) One or more second additives selected from the group consisting of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiFOB), lithium bis(oxalate borate) (LiB(C2O4)2, LiBOB), vinylene carbonate (VC), and ethylene ethylene carbonate (VEC): [Chemical Formula 1]

[0009] In the chemical formula 1, the carbon atoms in the ring are connected by single or double bonds; X is oxygen or sulfur; The Y is oxygen or sulfur; The Z 1 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 alkenyl, substituted or unsubstituted C 1-10 Alkyne, substituted or unsubstituted C 3-10 cycloalkyl, substituted or unsubstituted C 1-12 Heteroalkyl, substituted or unsubstituted C 1-6 Heterocyclic alkyl, substituted or unsubstituted C 1-10 Amine groups and substituted or unsubstituted C 1-10 Groups composed of acyl groups; The Z 2 and Z 3 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl and substituted or unsubstituted C 1-10 Alkyne group.

[0010] In one embodiment of the present invention, the substituted alkyl, alkenyl, amino, acyl, alkynyl, cycloalkyl, silyl, alkoxy, heteroalkyl, and heterocycloalkyl groups may each be independently substituted by one or more substituents selected from the group consisting of alkoxy, alkynoxy, heteroaryl, alkenyl, heterocycloalkyl, carbonyl, halogen, hydroxyl, alkenyloxy, carboxyl, carbonate, alkyl, alkynyl, amino, cycloalkyl, silyl, sulfonate, phosphate, thiamethoxam, nitro, cyano, heteroalkyl, cycloalkyl, aryl, and ether groups.

[0011] In one embodiment of the present invention, the electrolyte may further include one or more additives selected from the group consisting of unsaturated cyclic carbonates, cyclic sulfate lactones and nitrile compounds.

[0012] In one embodiment of the present invention, the unsaturated cyclic carbonate may be selected from the group consisting of phenyl carbonate, vinyl carbonate and allyl carbonate.

[0013] In one embodiment of the present invention, the electrolyte may further contain an organic solvent.

[0014] Another aspect of the present invention provides a lithium-ion battery comprising the non-aqueous electrolyte for a secondary battery.

[0015] In one embodiment of the present invention, a secondary battery may be provided, wherein the battery includes: an electrode assembly including a positive electrode, a negative electrode and a separator for isolating the positive electrode and the negative electrode; a housing for housing the electrode assembly; and an electrolyte contained in the housing and impregnating the electrode assembly.

[0016] Beneficial effects The secondary battery according to the present invention, which includes an electrolyte additive and a secondary battery electrolyte, can have improved room temperature life performance. Attached Figure Description

[0017] Figure 1 A cross-sectional view of a secondary battery comprising an electrolyte and an electrolyte additive according to an embodiment of the present invention is shown.

[0018] Figure 2 The results of an analysis of the room temperature lifetime performance of a secondary battery according to an embodiment of the present invention are shown.

[0019] [Explanation of Labels in the Attached Image] 1: Secondary battery 10: Upper shell 20: Spring 30: Gasket 40: Positive electrode 50: Diaphragm 60: Negative electrode 70: Washer 80: Lower shell Best mode The accompanying drawings illustrate one embodiment of the invention. However, the inventive concept can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of the inventive concept to those skilled in the art. The same reference numerals denote the same constituent elements.

[0020] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the inventive concept. As used herein, the singular form is intended to include the plural form, which includes "at least one," unless the context clearly specifies otherwise. "At least one" should not be construed as limited to the singular. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The terms "comprising" and / or "including" as used in the summary of the invention refer to the presence of features, regions, integers, steps, actions, constituent elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, integers, steps, actions, constituent elements, components, and / or combinations thereof.

[0021] Unless otherwise defined, all techniques (including technical and scientific terms) used in this specification have the same meaning as commonly understood by those skilled in the art. Furthermore, it should be understood that terms defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and this disclosure, rather than an idealized or overly formal meaning.

[0022] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or foreseen by the applicant or those skilled in the art will occur to them. Therefore, the appended claims, both applicable and amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0023] In this invention, the term "isomer" refers to a compound or salt thereof of the present invention that has the same chemical formula or molecular formula but differs in structure or space. These isomers include structural isomers (e.g., tautomers), stereoisomers (e.g., R or S isomers with an asymmetric carbon center, geometric isomers (trans, cis), etc.), and optical isomers. These isomers and mixtures thereof are also included within the scope of this invention.

[0024] In this invention, unless otherwise stated, the term "alkyl" can be straight-chain or branched, and the number of carbon atoms is not particularly limited, but can be 1 to 7. Specific examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, and n-heptyl.

[0025] In this specification, unless otherwise stated, the term "alkenyl" can be straight-chain or branched, and can refer to an alkyl group containing one or more double bonds. The number of carbon atoms is not particularly limited and can be 2 to 6. Specific examples include, but are not limited to, vinyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 3-methyl-1-butenyl, and 1,3-butadienyl.

[0026] In this specification, unless otherwise stated, the term "alkynyl" can be straight-chain or branched, and can refer to an alkyl group containing one or more triple bonds. The number of carbon atoms is not particularly limited and can be 2 to 6. Specific examples include, but are not limited to, ethynyl, propynyl, butynyl, and pentyynyl.

[0027] In this specification, the term "amine group" may be selected from the group consisting of -NH2, alkylamine, N-alkylarylamine, arylamine, N-arylheteroarylamine, N-alkylheteroarylamine, and heteroarylamine, and the number of carbon atoms is not particularly limited, and may be 1 to 30. More specific examples of amine groups include, but are not limited to, methylamine, dimethylamine, ethylamine, diethylamine, aniline, naphthylamine, benzidine, anthraceneamine, 9-methylanthraphenamine, diphenylamine, xylylamine, N-phenyltoluidine, triphenylamine, N-phenylbenzidine, N-phenylnaphthylamine, N-biphenylnaphthylamine, N-naphthylfluoreneamine, N-phenylphenanthreneamine, N-biphenylphenanthreneamine, N-phenyltriphenylamine, N-phenanthrenefluoreneamine, and N-biphenylfluoreneamine, etc.

[0028] In this specification, the term "heteroalkyl" refers to an alkyl group containing one or more of O, N, Si, B, Se, P, and S as heteroatoms, with no particular limitation on the number of carbon atoms, which can be 1 to 6. Examples of heteroalkyl groups include, but are not limited to, -CH2-CH2-O-CH3, -CH2-CH2-NH-CH3, -CH2-CH2-N(CH3)-CH3, and -CH2-S-CH2-CH3.

[0029] In this specification, the term "cycloalkyl" refers to a non-aromatic carbon ring, which is not particularly limited in the number of carbon atoms and can be 3 to 12. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl.

[0030] In this specification, the term "heterocyclic alkyl" refers to a cycloalkyl group containing one or more of O, N, Si, B, Se, P, and S as heteroatoms, with no particular limitation on the number of carbon atoms, which can be 3 to 12. Examples of heterocyclic alkyl groups include, but are not limited to, epoxy groups, tetrahydrofuranyl groups, tetrahydropyranyl groups, tetrahydrothiophenyl groups, and tetrahydropyrroleyl groups.

[0031] In this specification, the term "aryl" is not particularly limited, but the number of carbon atoms can be 6 to 20; or 6 to 12. The aryl group may include monocyclic aryl groups, such as phenyl, biphenyl, and terphenyl, but is not limited thereto. The polycyclic aryl group may include naphthyl, anthraceneyl, phenanthryl, pyrene, peryl, trefyl, fluorene, etc., but is not limited thereto.

[0032] In this specification, the term "heteroaryl" refers to an aryl group containing one or more of O, N, Si, B, Se, P, and S as heteroatoms, with no particular limitation on the number of carbon atoms, which can be 5 to 20. Examples of heteroaryl groups include, but are not limited to, xanthene, thioxanthen, thiophene, furanyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, oxadiazolyl, triazolyl, pyridyl, bipyridyl, pyrimidinyl, triazinyl, acridinel, pyridazinyl, quinolinyl, quinazolinyl, quinoxolinyl, o-benzodiazinyl, pyridinopyrimidinyl, pyridinopyrazinyl, pyrazinopyrazinyl, isoquinolinyl, indolyl, carbazole, benzoxazolyl, benzoimidazolyl, benzothiazolyl, benzocarbazole, benzothiaphenyl, dibenzothiaphenyl, benzofuranyl, phenanthroline, isoxazolyl, thiadiazolyl, phenylthiazinyl, and dibenzofuranyl.

[0033] In this specification, the term "alkoxy" refers to an alkyl group bonded to oxygen, and oxygen may be bonded to said alkyl group. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, and pentoxy.

[0034] In this specification, the term "acyl" refers to the portion remaining after removing the OH group from the carboxyl group -COOH of a carboxylic acid. There is no particular limitation on the number of carbon atoms; it can be 1 to 6. Examples of acyl groups include, but are not limited to, acetyl, propionyl, malonyl, and benzoyl groups.

[0035] In this specification, the term "silyl" may be represented as -SiR3, and examples of silyl may be selected from, but are not limited to, alkylsilyl, arylsilyl, alkylarylsilyl, and heteroarylsilyl. More specific examples include, but are not limited to, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, vinyldimethylsilyl, propyldimethylsilyl, triphenylsilyl, diphenylsilyl, and phenylsilyl.

[0036] In this specification, the term "substituted or unsubstituted" can mean substituted or unsubstituted by one or more groups selected from the group consisting of alkoxy, alkynoxy, heteroaryl, alkenyl, heterocycloalkyl, carbonyl, halogen, hydroxyl, alkenoxy, carboxyl, carbonate, alkyl, alkynyl, amino, cycloalkyl, silyl, sulfonate, phosphate, thiamethoxam, nitro, cyano, heteroalkyl, cycloalkyl, aryl, and ether.

[0037] Furthermore, throughout this specification, unless otherwise expressly stated, the same symbols may have the same meaning.

[0038] This invention relates to a compound for electrolytes, a compound for electrolyte additives, an electrolyte substance, an electrolyte additive, an electrolyte for secondary batteries, and a secondary battery.

[0039] The electrolyte for secondary batteries of the present invention may contain the following additives: An electrolyte for a secondary battery, comprising: (A) a first additive represented by the following chemical formula 1; and (B) One or more second additives selected from the group consisting of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiFOB), lithium bis(oxalate borate) (LiB(C2O4)2, LiBOB), vinylene carbonate (VC) and ethylene ethylene carbonate (VEC).

[0040] The compound can be represented by the following chemical formula 1.

[0041] [Chemical Formula 1]

[0042] In the chemical formula 1, the carbon atoms in the ring are connected by single or double bonds; X is oxygen or sulfur; The Y is oxygen or sulfur; The Z 1 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 alkenyl, substituted or unsubstituted C 1-10 Alkyne, substituted or unsubstituted C 3-10 cycloalkyl, substituted or unsubstituted C 1-12 Heteroalkyl, substituted or unsubstituted C 1-6 Heterocyclic alkyl, substituted or unsubstituted C 1-10 Amine groups and substituted or unsubstituted C 1-10 Groups composed of acyl groups; The Z 2 and Z 3 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl and substituted or unsubstituted C 1-10 Alkyne group.

[0043] In one embodiment of the present invention, the compound represented by Chemical Formula 1 is a compound derived from heterocyclic compounds and can be added to the electrolyte as an additive for lithium secondary batteries. The additive of the present invention minimizes the increase in resistance of the lithium secondary battery while forming a stable SEI (Solid Electrolyte Interphase) film on the negative electrode surface. Therefore, by suppressing the decrease in SEI passivation at high temperatures, the degradation of the negative electrode can be prevented, and room temperature lifetime can be improved by forming a film that facilitates lithium migration.

[0044] In the compounds of the present invention represented by Chemical Formula 1, specifically, the Z 1 Each can be independently selected from hydrogen, substituted or unsubstituted C atoms. 1-10 Alkyl, substituted or unsubstituted C 1-10 alkenyl, substituted or unsubstituted C 1-10 Alkyne, substituted or unsubstituted C 1-10 Amine groups and substituted or unsubstituted C 1-10 A group composed of acyl groups.

[0045] In the compounds of the present invention represented by Chemical Formula 1, more specifically, the Z 2 and Z 3 Each can be independently selected from hydrogen, substituted or unsubstituted C atoms. 1-10 A group composed of alkyl groups.

[0046] In this invention, the substituted alkyl, alkenyl, amino, acyl, alkynyl, cycloalkyl, silyl, alkoxy, heteroalkyl, and heterocycloalkyl groups can each be independently substituted by one or more substituents selected from the group consisting of alkoxy, alkynyl, heteroaryl, alkenyl, heterocycloalkyl, carbonyl, halogen, hydroxyl, alkenyloxy, carboxyl, carbonate, alkyl, alkynyl, amino, cycloalkyl, silyl, sulfonate, phosphate, thiaphosphate, nitro, cyano, heteroalkyl, cycloalkyl, aryl, and ether groups. For example, the substituted alkoxy group can be substituted by alkenyl, alkynyl, amino, cycloalkyl, carbonyl, or silyl; the substituted heterocycloalkyl group can be substituted by carbonyl; the substituted carboxyl group can be substituted by heteroaryl, alkenyl, heterocycloalkyl, carbonyl-substituted heterocycloalkyl, or halogen; and the substituted carbonate group can be substituted by alkyl or alkynyl. In addition, the substituted sulfonate group can be replaced by an alkyl, alkenyl, or halogen-substituted alkyl group, and the substituted sulfonate group and thiamethoxam group can each be independently replaced by an alkyl group.

[0047] The electrolyte for secondary batteries of the present invention comprises a compound represented by the chemical formula 1 as a first additive, and may further comprise a second additive. For example, it may comprise one or more second additives selected from the group consisting of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiFOB), lithium bis(oxalate borate) (LiB(C2O4)2, LiBOB), vinylene carbonate (VC), and ethylene ethylene carbonate (VEC).

[0048] In an alternative embodiment of the invention, in addition to the first and second additives, the additives may further comprise one or more additives selected from the group consisting of unsaturated cyclic carbonates, cyclic sulfate lactones, and nitrile compounds.

[0049] In this invention, the unsaturated cyclic carbonate is a cyclic carbonate with carbon-carbon unsaturated bonds, such as carbonates with carbon-carbon double bonds, carbon-carbon triple bonds, etc. There are no particular restrictions, and any unsaturated cyclic carbonate can be used.

[0050] As an additional additive of the present invention, the unsaturated cyclic carbonate may be added one or more selected from, for example, the group consisting of vinylene carbonate, phenyl carbonate, vinyl carbonate, and allyl carbonate. As the vinylene carbonate, one or more selected from methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, and 4,5-diallyl vinylene carbonate may be added.

[0051] As an additional additive of the present invention, cyclic sulpholactones may be added. In one embodiment, from the viewpoint of improving preservation properties, 1,3-propane sulpholactone, 1-fluoro-1,3-propane sulpholactone, 2-fluoro-1,3-propane sulpholactone, 3-fluoro-1,3-propane sulpholactone, 1,4-butane sulpholactone, methylene methane disulfonate, and ethyl methane disulfonate may be added. One or more of the group consisting of 1,3-propane sulpholactone, 1-fluoro-1,3-propane sulpholactone, 2-fluoro-1,3-propane sulpholactone, and 3-fluoro-1,3-propane sulpholactone may be added.

[0052] As a specific embodiment of the present invention, the compound represented by chemical formula 1 may include at least one compound selected from the group consisting of the following chemical formulas or isomers thereof:

[0053]

[0054]

[0055] Furthermore, the compounds of the present invention may have a chiral carbon center and thus may exist as R or S isomers, racemates, enantiomers alone or mixtures, diastereomers alone or mixtures, and all such stereoisomers and mixtures thereof may fall within the scope of the present invention.

[0056] Based on the total weight of the entire electrolyte, the content of the additives of the present invention may be about 0.1% by weight or higher, but is not limited thereto, and an appropriate amount may be used within the said content range as needed.

[0057] If the content of the additives in the electrolyte is too high, the battery may expand due to excessive gas, thereby reducing its lifespan.

[0058] From this perspective, based on the total weight of the electrolyte, the content of the additive can be 0.01 to 10 wt%; 0.01 to 9 wt%; 0.01 to 8 wt%; 0.01 to 7 wt%; 0.01 to 6 wt%; 0.01 to 5 wt%; 0.01 to 4 wt%; 0.01 to 3 wt%; 0.01 to 2 wt%; 0.01 to 1 wt%; 0.1 to 10 wt%; 0.1 to 9 wt%; 0.1 to 8 wt%; 0.1 to 7 wt%; 0.1 to 6 wt% 0.1 to 5 wt%; 0.1 to 4 wt%; 0.1 to 3 wt%; 0.1 to 2 wt%; 0.1 to 1 wt%; 1 to 10 wt%; 1 to 9 wt%; 1 to 8 wt%; 1 to 7 wt%; 1 to 6 wt%; 1 to 5 wt%; 1 to 4 wt%; 1 to 3 wt%; 1 to 2 wt%; 5 to 10 wt%; 5 to 9 wt%; 5 to 8 wt%; 5 to 7 wt%; or 5 to 6 wt%, provided that its use as an overcharge preventer does not reduce the lifespan characteristics by any extent.

[0059] On the other hand, in one embodiment, the electrolyte for the secondary battery may further include lithium salt and organic solvent.

[0060] The concentration of the lithium salt in the electrolyte can be from about 0.01 to 2.0 M, but is not necessarily limited to this range; an appropriate concentration can be used as needed. Within the concentration range, further improved battery characteristics can be obtained.

[0061] There are no particular restrictions on the lithium salt used in the electrolyte; any lithium salt that can be used in the relevant technical field can be used. For example, lithium salts selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiC2F6NO4S2, LiB(C2O4)2, and LiN(C x F 2x+1 SO2)(C y F 2y+1 One or more of the following groups: SO2 (where x and y are independent integers equal to or greater than 1), LiCl, and LiI.

[0062] The organic solvent may include one or more selected from the group consisting of dialkyl carbonates, cyclic carbonates, linear or cyclic esters, linear or cyclic amides, aliphatic nitriles, linear or cyclic ethers, and their derivatives.

[0063] Specifically, the organic solvent may include one or more selected from the group consisting of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), butene carbonate, ethyl propionate (EP), ethyl butyrate, acetonitrile (AN), succinic anionyl (SN), dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, γ-valerolactone, γ-butyrolactone, and tetrahydrofuran, but is not limited thereto; any organic solvent that can be used in organic electrolytes within the technical field to which this invention pertains may be used.

[0064] Another aspect of the present invention provides a secondary battery comprising the electrolyte for a secondary battery.

[0065] The secondary battery includes: an electrode assembly comprising a positive electrode, a negative electrode, and a separator for isolating the positive electrode and the negative electrode; Housing for accommodating the electrode assembly; and An electrolyte, which serves as the electrolyte for the secondary battery, is contained within the housing and impregnates the electrode assembly.

[0066] The form of the secondary battery is not particularly limited, and it includes lithium-ion batteries, lithium-ion polymer batteries, lithium-sulfur batteries, lithium-air batteries, etc., but is not limited to these.

[0067] For example, if the secondary battery is a lithium-ion battery, it can be prepared by the following method.

[0068] First, prepare the positive electrode.

[0069] For example, a positive electrode active material composition is prepared, comprising a positive electrode active material, a conductive material, a binder, and a solvent. The positive electrode active material composition is then directly coated onto a metal current collector to prepare a positive electrode plate. Alternatively, the positive electrode active material composition is cast onto a separate support, and a film peeled from the support is then laminated onto the metal current collector to prepare a positive electrode plate. The positive electrode is not limited to the forms listed above and may also be in forms other than those described.

[0070] The positive electrode active material is a lithium-containing metal oxide, and any material commonly used in the art can be used without limitation. For example, one or more composite oxides of lithium with metals selected from cobalt, manganese, nickel, and combinations thereof can be used. As a specific example, a lithium oxide can be used. a A 1-b B b D2 (in the formula, 0.90≤a≤1.8, 0≤b≤0.5); Li a E 1-b B b O 2-c D c (In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B b O 4-c D c (In the formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B c D α (In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-b-c Co b B c O 2-α F α (In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Co b B c O 2-α F2 (in the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c D α(In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-b-c Mn b B c O 2-α F α (In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c O 2-α F2 (in the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2 (in the formula, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d GeO2 (in the formula, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O2 (in the formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (in the formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li a MnG b O2 (in the formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (in the formula, 0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3 (0≤f≤2); Li (3-f) Fe2(PO4)3 (0≤f≤2); any compound represented by the chemical formula of LiFePO4: In the chemical formula, A is Ni, Co, Mn or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; F is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; I is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0071] For example, LiCoO2, LiMn x O 2x (x=1,2), LiNi 1-x Mn x O 2x (0) <x<1)、LiNi 1-x-y Co x Mn y O2 (0≤x≤0.5, 0≤y≤0.5), LiFePO4, etc.

[0072] Of course, compounds with a coating on the surface of the compound can also be used, or mixtures of the compound and coated compounds can also be used. The coating may comprise a coating element compound such as an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxide formed from a coating element. The compounds forming these coatings may be amorphous or crystalline. The coating element contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating formation process can employ any coating method (e.g., spraying, dip coating, etc.) as long as the method can coat the element onto the compound and does not adversely affect the physical properties of the positive electrode active material. Since this is readily understood by those skilled in the art, a detailed description will be omitted.

[0073] Carbon black, graphite particles, etc., can be used as the conductive material, but are not limited to these. Any conductive material that can be used in the relevant technical field can be used.

[0074] As the adhesive, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene and mixtures thereof, or styrene-butadiene rubber-based polymers can be used, but are not limited thereto; any adhesive that can be used in the relevant technical field can be used.

[0075] As the solvent, N-methylpyrrolidone, acetone, water, etc. can be used, but not limited thereto, and any solvent that can be used in the relevant technical field can be used.

[0076] The contents of the positive electrode active material, conductive material, binder, and solvent are at levels commonly used in lithium-ion batteries. Depending on the use and composition of the lithium-ion battery, one or more of the conductive material, binder, and solvent can be omitted.

[0077] Then, a negative electrode is prepared.

[0078] For example, a negative electrode active material composition mixed with a negative electrode active material, a conductive material, a binder, and a solvent is prepared. The negative electrode active material composition is directly coated on a metal current collector and dried to prepare a negative electrode plate. Different from this, the negative electrode active material composition is cast on a separate support, and then the film peeled off from the support can be laminated on the metal current collector to prepare a negative electrode plate.

[0079] As the negative electrode active material, any negative electrode material of a lithium-ion battery that can be used in the relevant technical field can be used. For example, it can include one or more selected from the group consisting of lithium metal, a metal alloyable with lithium, a transition metal oxide, a non-transition metal oxide, and a carbon-based material.

[0080] For example, the metal alloyable with lithium can be Si, Sn, Al, Ge, Pb, Bi, Sb, a Si-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combined element thereof, but not Si), a Sn-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combined element thereof, but not Sn), etc. The element Y can be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. <00003​​​​​​​​​The carbon-based material can be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon can be amorphous, plate-like, flake-like, spherical, or fibrous graphite, such as natural graphite or artificial graphite, etc., and the amorphous carbon can be soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbides, and calcined coke, etc.

[0084] The same materials as those used in the positive electrode active material composition can be used as conductive materials and binders in the negative electrode active material composition.

[0085] The contents of the negative electrode active material, conductive material, binder, and solvent are at levels commonly used in lithium-ion batteries. Depending on the application and composition of the lithium-ion battery, one or more of the conductive material, binder, and solvent may be omitted.

[0086] Then, prepare a diaphragm to isolate the positive and negative electrodes.

[0087] As the separator, all materials commonly used in lithium-ion batteries can be used. Materials with low resistance to ion movement of the electrolyte and excellent electrolyte permeability can be used. For example, the separator can be selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or combinations thereof, and can be in the form of nonwoven or woven fabric. For example, in lithium-ion batteries, rollable separators such as polyethylene and polypropylene can be used, and in lithium-ion polymer batteries, separators with excellent organic electrolyte permeability can be used. For example, the separator can be prepared by the following methods.

[0088] A membrane composition is prepared by mixing a polymer resin, a filler, and a solvent. The membrane composition can be directly coated onto the upper part of the electrode and dried to form a membrane. Alternatively, the membrane composition can be cast onto a support and dried, and then a membrane layer peeled from the support is stacked onto the upper part of the electrode to form a membrane.

[0089] There are no particular limitations on the polymer resin used to prepare the diaphragm; any substance used for electrode plate binders can be used. For example, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or mixtures thereof can be used.

[0090] Next, prepare the electrolyte for the secondary battery.

[0091] like Figure 1As shown, the secondary battery 1 includes a positive electrode 40, a negative electrode 60, and a separator 50. The positive electrode 40, the negative electrode 60, and the separator 50 are housed in the housing 10 and the housing 80 by winding or folding. Then, electrolyte is injected into the housing 10 and the housing 80 to complete the secondary battery 1.

[0092] The casing can have various shapes depending on the purpose and design specifications of the secondary battery, and can be formed into various sizes and shapes, such as square, thin film, button, etc.

[0093] As an example, the secondary battery may be a button cell. As a specific example, the secondary battery may be a lithium-ion battery.

[0094] A separator can be disposed between the positive and negative electrodes to form an electrode assembly. After the electrode assembly is stacked into a dual-cell structure, it is immersed in an electrolyte, and the resulting product is contained in a bag and sealed to complete the lithium-ion polymer battery.

[0095] Furthermore, a plurality of the aforementioned electrode assemblies are stacked to form a battery pack, which can be used in all devices requiring high capacity and high power. For example, it can be used in laptops, smartphones, and electric vehicles. Detailed Implementation

[0096] The present invention will be described in detail below through preparation examples, embodiments, and experimental examples.

[0097] However, the manufacturing examples, embodiments, and experimental examples described later are merely specific examples of one aspect of the invention, and the invention is not limited thereto.

[0098] <Preparation Example 1> Preparation of Compound 1

[0099] <Compound 1> In a 250 mL three-necked flask, 2-oxazolidinone (8 g, 0.09 mol) and triethylamine (18.6 g, 0.18 mol) were dissolved in dichloromethane (80 mL) and cooled to 0 °C. Propylcarbamate (12.5 g, 0.1 mol) was added dropwise and stirred for 2 hours.

[0100] In a flask, add water (80 mL), stir vigorously, and allow to separate into layers. Extract the aqueous layer with dichloromethane (100 mL × 2). Add anhydrous magnesium sulfate to the organic layer, stir for 5 minutes, and filter to remove the solid. Concentrate the filtrate and purify using a column chromatography column.

[0101] Compound 1 (13 g) was obtained (yield: 84%), after being subjected to... 1 H-NMR and 13C-NMR confirmed.

[0102] 1 H-NMR (400 MHz, CDCl3) d 4.86 (d, 2H,J=0.006Hz), 4.42-4.38 (m, 2H), 4.08-4.04(m, 2H), 2.55-2.54 (m, 1H) 13 C-NMR (400 MHz, CDCl3) d 151.7, 150.3,76.7, 76.1, 61.8, 54.4, 43.4 <Preparation Example 2> Preparation of Compound 2

[0103] <Compound 2> In a 250 mL three-necked flask, 2-thiazolidinone (8 g, 0.08 mol) and triethylamine (15.7 g, 0.16 mol) were dissolved in dichloromethane (80 mL) and cooled to 0 °C. Propylcarbamate (10.5 g, 0.09 mol) was added dropwise and stirred for 2 hours.

[0104] In a flask, add water (80 mL), stir vigorously, and allow to separate into layers. Extract the aqueous layer with dichloromethane (100 mL × 2). Add anhydrous magnesium sulfate to the organic layer, stir for 5 minutes, and filter to remove the solid. Concentrate the filtrate and purify using a column chromatography column.

[0105] Compound 2 (12 g) was obtained (yield: 84%), after being subjected to... 1 H-NMR and 13 C-NMR confirmed.

[0106] 1H-NMR (400 MHz, CDCl3) d 4.84 (d, 2H,J=0.006Hz), 4.18-4.14 (m, 2H), 3.32-3.28 (m, 2H), 2.54-2.53 (m, 1H) 13C-NMR (400 MHz, CDCl3) d 170.2, 149.9,76.8, 76.0, 54.3, 47.6, 25.2 <Preparation Example 3> Battery Preparation A mixture of 96 wt% artificial graphite (S360-L2-H Tiangin BTR New energy technology Co., Ltd.), 1 wt% SuperP (TIMCAL), 1.5 wt% styrene-butadiene rubber (SBR) binder (ZEON), and 1.5 wt% carboxymethyl cellulose (CMC, Sigma-Aldrich) was added to distilled water and stirred with a mechanical stirrer for 60 minutes to prepare a negative electrode active material slurry. The slurry was coated onto a 30 μm thick copper current collector using a doctor blade to a thickness of approximately 60 μm. The mixture was dried in a hot air dryer at 100°C for 1 hour, then dried again under vacuum for 8 hours, and finally rolled to prepare the negative electrode plate.

[0107] 96% by weight of LiNi 0.6 Mn 0.2 Co 0.2 O2, 2% by weight of superP (TIMCAL) as a conductive material, and 2% by weight of polyvinylidene fluoride (PVdF, Sigma-Aldrich) were mixed and added to N-methyl-2-pyrrolidone solvent. The mixture was stirred with a mechanical stirrer for 30 minutes to prepare a positive electrode active material slurry. The slurry was coated with an aluminum current collector with a thickness of about 60 μm using a doctor blade. The slurry was dried in a hot air dryer at 100°C for 1 hour, and then dried again under vacuum for 8 hours. The mixture was then rolled to prepare the positive electrode plate.

[0108] Lithium batteries were prepared using polypropylene with a thickness of 14 μm as a separator and the additives contained in the comparative examples and Examples 1 to 7 described later as electrolytes.

[0109] <Comparative Example 1> 1 M LiPF6 was dissolved as a lithium salt in a solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1.

[0110] An electrolyte is prepared by adding 0.5% by weight of propynyl 1H-imidazolium-1-carboxylic acid ester, represented by the following chemical formula, to the prepared electrolyte relative to 100% by weight of the organic electrolyte.

[0111]

[0112] <Comparative Example 2> 1 M LiPF6 was dissolved as a lithium salt in a solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1.

[0113] An electrolyte is prepared by adding 1% by weight of a vinylene carbonate, represented by the following chemical formula, to the prepared electrolyte relative to 100% by weight of the organic electrolyte.

[0114]

[0115] <Comparative Example 3> 1 M LiPF6 was dissolved as a lithium salt in a solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1.

[0116] An electrolyte is prepared by adding 1% by weight of lithium difluorophosphate to the prepared electrolyte relative to 100% by weight of the organic electrolyte.

[0117]

[0118] <Comparative Example 4> The electrolyte was prepared in the same manner, except that the 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with Compound 1.

[0119] <Comparative Example 5> The electrolyte was prepared in the same manner, except that the 1H-imidazol-1-carboxylic acid ester in Comparative Example 1 was replaced with Compound 2.

[0120] <Example 1> The electrolyte was prepared in the same manner, except that 0.5 wt% of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 0.5 wt% of Compound 1 and 0.5 wt% of vinylene carbonate.

[0121] <Example 2> The electrolyte was prepared in the same manner, except that 0.5 wt% of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 0.5 wt% of Compound 2 and 0.5 wt% of vinylene carbonate.

[0122] <Example 3> The electrolyte was prepared in the same manner, except that 0.5% by weight of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 0.5% by weight of Compound 1 and 1% by weight of vinylene carbonate.

[0123] <Example 4> The electrolyte was prepared in the same manner, except that 0.5% by weight of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 1% by weight of Compound 1 and 1% by weight of vinylene carbonate.

[0124] <Example 5> The electrolyte was prepared in the same manner, except that 0.5% by weight of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 0.5% by weight of Compound 2 and 1% by weight of vinylene carbonate.

[0125] <Example 6> The electrolyte was prepared in the same manner, except that 0.5% by weight of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 1% by weight of Compound 2 and 1% by weight of vinylene carbonate.

[0126] <Example 7> The electrolyte was prepared in the same manner, except that 0.5% by weight of 1H-imidazolium-1-carboxylic acid ester in Comparative Example 1 was replaced with 1% by weight of Compound 2 and 1% by weight of lithium difluorophosphate.

[0127] <Experimental Example 1> Room Temperature Lifetime Performance Evaluation To evaluate the performance of the electrolyte containing the additives of the present invention, a room temperature lifetime performance evaluation was performed. Under constant current / constant voltage (CC / CV) conditions at 25°C, the lithium secondary battery was charged to 4.2 V at a constant current rate of 1.0 C-level, maintained at 4.2 V in constant voltage mode, cut-off at a 0.05 C-level, and discharged to 2.7 V at a 1.0 C-level. One cycle was performed under these charge-discharge conditions, repeated 200 times. The evaluation results of the additives in the comparative examples and Examples 1 to 4 are shown in Table 1 and... Figure 2 middle.

[0128] Table 1

[0129] From Table 1 and Figure 2 It can be confirmed that in Examples 1 to 6, the addition of vinylene carbonate additives to Comparative Examples 4 and 5 resulted in a further improvement in capacity retention. Additionally, in Example 7, the addition of lithium difluorophosphate additives to Comparative Example 5 resulted in an improvement in capacity retention.

[0130] <Experimental Example 2> Evaluation of Resistance Improvement Performance The batteries prepared according to the examples were charged at 1C to 4.2 V, discharged to SOC50, and then discharged for 10 seconds at each of four C-rates (0.5, 1, 2, 3C), and the initial DC resistance (DC-IR) was measured. After charging at 1C to 4.2 V and performing 200 charge-discharge cycles at room temperature, the DC resistance (DC-IR) was measured using the same method as the initial DC resistance measurement. The percentages compared to the initial DC-IR are shown in Table 2.

[0131] Table 2

[0132] As can be confirmed from Table 2, in Comparative Examples 2 and 3, in the examples where the compounds prepared according to the present invention were combined, although the initial discharge resistance value was higher than that of the comparative examples, the discharge resistance after 200 charge cycles was lower than that of the comparative examples. That is, it was confirmed that the DC-IR growth rate was lower than that of the comparative examples. Therefore, it can be seen that when the compounds prepared according to the present invention are combined, the resistance growth rate is low, and a film that facilitates lithium migration is formed, thereby significantly reducing the DC-IR growth rate.

[0133] The description of this invention is for illustrative purposes only, and those skilled in the art should understand that the invention can be readily modified into other specific forms without changing the inventive concept or essential features. Therefore, the embodiments described above should be understood as exemplary in all respects, not restrictive. For example, each component described as a single type can be implemented separately, and similarly, components described as distributed can be implemented in combination.

[0134] The scope of this invention is embodied in the claims described later, and should be interpreted as including the meaning and scope of the claims, as well as all variations or modifications derived from the equivalent concept, within the scope of this invention.

Claims

1. An electrolyte for a secondary battery, comprising: (A) a first additive represented by the following chemical formula 1; and (B) One or more second additives selected from the group consisting of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiFOB), lithium bis(oxalate borate) (LiB(C2O4)2, LiBOB), vinylene carbonate (VC), and ethylene ethylene carbonate (VEC): [Chemical Formula 1] In the chemical formula 1, the carbon atoms in the ring are connected by single or double bonds; X is oxygen or sulfur; The Y is oxygen or sulfur; The Z 1 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 alkenyl, substituted or unsubstituted C 1-10 Alkyne, substituted or unsubstituted C 3-10 cycloalkyl, substituted or unsubstituted C 1-12 Heteroalkyl, substituted or unsubstituted C 1-6 Heterocyclic alkyl, substituted or unsubstituted C 1-10 Amine groups and substituted or unsubstituted C 1-10 Groups composed of acyl groups; The Z 2 and Z 3 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl and substituted or unsubstituted C 1-10 Alkyne group.

2. The electrolyte for secondary batteries according to claim 1, wherein, The Z 1 Each is independently selected from hydrogen, substituted or unsubstituted C. 1-10 Alkyl, substituted or unsubstituted C 1-10 alkenyl, substituted or unsubstituted C 1-10 Alkyne, substituted or unsubstituted C 1-10 Amine groups and substituted or unsubstituted C 1-10 A group composed of acyl groups.

3. The electrolyte for secondary batteries according to claim 1, wherein, The Z 2 and Z 3 Each is independently selected from hydrogen and substituted or unsubstituted C atoms. 1-10 A group composed of alkyl groups.

4. The electrolyte for secondary batteries according to claim 1, wherein, The substituted alkyl, alkenyl, alkynyl, cycloalkyl, heteroalkyl, heterocycloalkyl, amino, and acyl groups are each independently substituted by one or more substituents selected from the group consisting of carbonyl, halogen, hydroxyl, cyano, alkyl, alkenyl, alkynyl, heteroalkyl, alkoxy, alkenoxy, alkynoxy, amino, and nitro.

5. The electrolyte for secondary batteries according to claim 1, wherein, The electrolyte further comprises one or more additives selected from the group consisting of unsaturated cyclic carbonates, cyclic sulfate lactones, and nitrile compounds.

6. The electrolyte for secondary batteries according to claim 5, wherein, The unsaturated cyclic carbonate is a phenyl carbonate or an allyl carbonate.

7. The electrolyte for secondary batteries according to claim 1, wherein, The compound represented by chemical formula 1 is a compound selected from the group consisting of the following chemical formulas or their isomers: The electrolyte for the secondary battery comprises at least one compound or an isomer thereof selected from the group consisting of the following chemical formulas: 。 8. The electrolyte for secondary batteries according to claim 1, wherein, The electrolyte further contains an organic solvent.

9. The electrolyte for a secondary battery according to claim 1, wherein, The secondary battery is a lithium-ion battery.

10. A secondary battery, comprising: An electrode assembly including a positive electrode, a negative electrode, and a diaphragm for isolating the positive electrode and the negative electrode; A housing for accommodating the electrode assembly; as well as An electrolyte, which is the electrolyte according to claim 1, is contained in the housing and impregnates the electrode assembly.

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