Nonaqueous electrolyte for secondary batteries, and secondary battery comprising same

Abstract

The present invention relates to a nonaqueous electrolyte for secondary batteries and a secondary battery comprising same. The secondary battery comprising the nonaqueous electrolyte for secondary batteries according to the present invention can have improved room-temperature lifespan performance due to an increase in capacity retention rate and a reduction in resistance.

Description

Non-aqueous electrolyte for secondary batteries and secondary batteries containing the same

[0001] The present invention relates to an electrolyte for a secondary battery, and more specifically, to a non-aqueous electrolyte for a secondary battery that exhibits improved cycle life and resistance reduction performance by including an additive.

[0002] Lithium secondary batteries are used as the primary power source for various portable electronic devices, including video cameras, mobile phones, and laptop computers. Rechargeable lithium secondary batteries offer an energy density per unit weight that is more than three times higher than conventional lead-acid, nickel-cadmium, nickel-metal hydride, and nickel-zinc batteries, and offer the advantage of fast charging.

[0003] However, because lithium secondary batteries operate at high operating voltages, aqueous electrolytes, which are highly reactive with lithium, cannot be used. Instead, non-aqueous organic electrolytes are commonly used. Non-aqueous electrolytes are manufactured by dissolving lithium salts in organic solvents. They must be stable at high voltages, exhibit high ionic conductivity and dielectric constant, and have low viscosity.

[0004] Furthermore, the materials used in the cathode, anode, and electrolyte can significantly affect a battery's performance, including voltage, lifespan, capacity, and stability. Therefore, improving the performance of electrolytes for lithium secondary batteries is essential to ensure improved lifespan characteristics and high-temperature stability.

[0005] Recent research is actively developing technologies across various areas, including improving the chemical stability of electrolytes, enhancing thermal safety, and enhancing high-power characteristics. In particular, the development of new electrolyte materials that can operate stably at high temperatures, additive technologies that suppress electrolyte decomposition, and technologies that optimize interaction with electrodes are attracting attention as key challenges for maximizing the performance of lithium secondary batteries.

[0006] Therefore, designing a highly optimized electrolyte system is essential to maximize the performance and safety of lithium secondary batteries.

[0007] The present invention aims to provide an electrolyte for a lithium secondary battery that can improve the life characteristics and stability of the lithium secondary battery.

[0008] In order to achieve the above purpose, in one aspect of the present invention, a non-aqueous electrolyte for a secondary battery including an additive, the electrolyte comprising:

[0009] lithium salt;

[0010] non-aqueous organic solvent; and

[0011] An additive comprising a compound represented by the following chemical formula 1;

[0012] Non-aqueous electrolyte for secondary batteries:

[0013]

[0014] In chemical formula 1,

[0015] R1 is halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 2-10 Alkenyl, substituted or unsubstituted C 2-10 alkynyl, or substituted or unsubstituted C 1-30 It's Amin,

[0016] R2 and R5 are each independently hydrogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, substituted or unsubstituted C 1-10 an alkynyl, or a substituted or unsubstituted cyano group,

[0017] R3 and R4 are each independently hydrogen, or substituted or unsubstituted C 1-10 It is alkyl,

[0018] R6 and R7 are each independently halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10Alkenyl, or substituted or unsubstituted C 1-10 It is alkynyl,

[0019] M is at least one metal cation selected from the group consisting of alkali metals, alkaline earth metals, transition metals and metalloids,

[0020] m and n are each independently integers from 1 to 3,

[0021] a is 0 or 1,

[0022] In the above substituted or unsubstituted, substitution means substitution with one or more substituents selected from the group consisting of deuterium, halogen group, alkyl group, alkenyl group, alkynyl group, heteroalkyl group, alkylaryl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, amine group, alkoxy group, alkenyloxy group, alkynyloxy group, carbonyl group, carboxyl group, carbonate group, sulfonate group, phosphate group, thiophosphate group, hydroxy group, nitro group, cyano group, and ether group.

[0023] A secondary battery including an electrolyte additive and an electrolyte for a secondary battery according to the present invention can have improved room temperature life performance.

[0024] FIG. 1 is an exploded perspective view of a secondary battery including an electrolyte and an electrolyte additive according to one embodiment of the present invention.

[0025] Figures 2 to 5 illustrate the results of analyzing room temperature life performance according to the type of additive according to various embodiments of the present invention.

[0026] 1: Secondary battery

[0027] 10: Upper case

[0028] 20: Spring

[0029] 30: Spacer

[0030] 40: Bipolar

[0031] 50: Membrane

[0032] 60: Cathode

[0033] 70: Gasket

[0034] 80: Lower case

[0035] In one embodiment of the present invention, the non-aqueous electrolyte for the secondary battery may include a lithium salt; a non-aqueous organic solvent; and an additive including a compound represented by the following chemical formula 1.

[0036] [Chemical Formula 1]

[0037]

[0038] In chemical formula 1,

[0039] R1 is halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, substituted or unsubstituted C 1-10 alkynyl, or substituted or unsubstituted C 1-30 It's Amin,

[0040] R2 and R5 are each independently hydrogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, substituted or unsubstituted C 1-10 an alkynyl, or a substituted or unsubstituted cyano group,

[0041] R3 and R4 are each independently hydrogen, or substituted or unsubstituted C 1-10 It is alkyl,

[0042] R6 and R7 are each independently halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, or substituted or unsubstituted C 1-10 It is alkynyl,

[0043] M is at least one metal cation selected from the group consisting of alkali metals, alkaline earth metals, transition metals and metalloids,

[0044] m and n are each independently integers from 1 to 3,

[0045] a is 0 or 1,

[0046] In the above substituted or unsubstituted, substitution means substitution with one or more substituents selected from the group consisting of deuterium, halogen group, alkyl group, alkenyl group, alkynyl group, heteroalkyl group, alkylaryl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, amine group, alkoxy group, alkenyloxy group, alkynyloxy group, carbonyl group, carboxyl group, carbonate group, sulfonate group, phosphate group, thiophosphate group, hydroxy group, nitro group, cyano group, and ether group.

[0047] In one embodiment of the present invention, the lithium salt is a non-aqueous electrolyte for a secondary battery, comprising at least one selected from the group consisting of LiPO2F2, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, LiN(CF3SO2)2, LiC4F9SO3, LiAlO2, LiAlCl4, LiC2F6NO4S2, LiCl, LiI, LiSCN, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiPF4(C2O4), LiPF2(C2O4)2, and LiP(C2O4)3.

[0048] In one embodiment of the present invention, the additive may be included in an amount of 0.1 wt% to 10 wt% based on the total weight of the electrolyte.

[0049] In one embodiment of the present invention, the non-aqueous organic solvent may include at least one selected from the group consisting of cyclic carbonates and chain carbonates.

[0050] In one embodiment of the present invention, the cyclic carbonate may include at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, vinylethylene carbonate, and fluoroethylene carbonate, and the chain carbonate may include at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, and ethyl propyl carbonate.

[0051] In one embodiment of the present invention, the non-aqueous electrolyte for a secondary battery may include at least one additional additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), and TMSPi (Tris(trimethylsilyl) Phosphite).

[0052] In one embodiment of the present invention, the additional additive may be included in an amount of 0.1 to 10 wt% relative to the weight of the non-aqueous electrolyte.

[0053] In another aspect of the present invention, a lithium secondary battery can be provided.

[0054] In one embodiment of the present invention, the lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator separating the positive electrode and the negative electrode; a case accommodating the electrode assembly; and an electrolyte solution accommodated in the case and immersing the electrode assembly.

[0055] One embodiment of the present invention is illustrated in the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals in the drawings indicate like elements.

[0056] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms including "at least one," unless the content clearly dictates otherwise. "At least one" should not be construed as limiting 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 "comprises" and / or "comprising" as used in the detailed description specify the presence of stated features, regions, integers, steps, operations, components, and / or ingredients, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, components, ingredients, and / or groups thereof.

[0057] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, it will be understood that terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning within the context of the relevant art and the present disclosure, and not in an idealized or overly formal sense.

[0058] While specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or unforeseen may occur to the applicant or those skilled in the art. Accordingly, the appended claims, as filed and as amended, are intended to encompass all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0059] In the present invention, the term "halogen" means an element belonging to group VIIA (group 17) of the periodic table, and may generally include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0060] In the present invention, the term "alkyl" may be straight-chain or branched unless otherwise specified, and the number of carbon atoms is not particularly limited, but may be 1 to 10. 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-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, etc.

[0061] As used herein, the term "alkenyl" refers to an alkyl group that may be straight or branched, unless otherwise specified, and that contains one or more double bonds. The number of carbon atoms is not particularly limited, but may be from 2 to 10. 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.

[0062] As used herein, the term "alkynyl" refers to an alkyl group that may be straight or branched, unless otherwise specified, and that contains one or more triple bonds. The number of carbon atoms is not particularly limited, but may be 2 to 10. Specific examples include, but are not limited to, an ethynyl group, a propynyl group, a butynyl group, and a pentynyl group.

[0063] In this specification, the term "amine" may be selected from the group consisting of -NH2, an alkylamine group, an N-alkylarylamine group, an arylamine group, an N-arylheteroarylamine group, an N-alkylheteroarylamine group, and a heteroarylamine group, and the number of carbon atoms is not particularly limited, but may be 1 to 30. More specific examples of amine groups include a methylamine group, a dimethylamine group, an ethylamine group, a diethylamine group, a phenylamine group, a naphthylamine group, a biphenylamine group, anthracenylamine group, a 9-methyl-anthracenylamine group, a diphenylamine group, a ditolylamine group, an N-phenyltolylamine group, a triphenylamine group, an N-phenylbiphenylamine group, an N-phenylnaphthylamine group, an N-biphenylnaphthylamine group; an N-naphthylfluorenylamine group, an N-phenylphenanthrenylamine group, an N-biphenylphenanthrenylamine group, Examples thereof include, but are not limited to, N-phenylfluorenylamine group, N-phenylterphenylamine group, N-phenanthrenylfluorenylamine group, and N-biphenylfluorenylamine group.

[0064] The term "cyano group" as used herein may be selected from the group consisting of -CN, an alkylcyano group, an arylcyano group, a heteroarylcyano group, an N-alkylcyano group, an N-arylcyano group, and a polycyclic cyano group, and the number of substituted carbon atoms is not particularly limited, but may be 1 to 10. More specific examples of the cyano group include, but are not limited to, a methylcyano group, an ethylcyano group, a propylcyano group, a butylcyano group, a pentylcyano group, a hexylcyano group, a phenylcyano group, a tolylcyano group, a naphthylcyano group, a cresylcyano group, and the like.

[0065] The term "heteroalkyl" as used herein refers to an alkyl containing one or more of O, N, Si, B, Se, P, and S as heteroatoms, and the number of carbon atoms is not particularly limited, but may be 1 to 6. Examples of heteroalkyl include, but are not limited to, -CH2-CH2-O-CH3, -CH2-CH2-NH-CH3, -CH2-CH2-N(CH3)-CH3, -CH2-S-CH2-CH3, etc.

[0066] As used herein, the term "alkylaryl group" refers to a functional group in which an alkyl group (-R) and an aryl group (-Ar) are bonded, and includes a structure in which an alkyl group is directly bonded to an aryl group. More specific examples of alkylaryl groups include, but are not limited to, a benzyl group, a tolyl group, an ethylphenyl group, and an isopropylphenyl group.

[0067] The term "cycloalkyl" as used herein refers to a non-aromatic carbon ring having, but is not particularly limited to, 3 to 12 carbon atoms. Examples of cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl.

[0068] The term "heterocycloalkyl" as used herein refers to a cycloalkyl containing at least one of O, N, Si, B, Se, P, and S as a heteroatom, and the number of carbon atoms is not particularly limited, but may be 3 to 12. Examples of heterocycloalkyl include, but are not limited to, epoxy, tetrahydrofuranyl, tetrahydropyranyl, tetrahydrothiophenyl, and tetrahydropyrrolyl.

[0069] The term "alkynyloxy group" as used herein may be represented by the structure -OC≡CR, and may be selected from the group consisting of a straight-chain or branched alkynyloxy group, a substituted alkynyloxy group, and a heteroalkynyloxy group. The number of substituted carbon atoms may be 2 to 10. More specific examples include, but are not limited to, an ethynyloxy group, a propynyloxy group, a butynyloxy group, and the like.

[0070] The term "aryl" as used herein is not particularly limited, but may have 6 to 20 carbon atoms; or 6 to 12 carbon atoms. Monocyclic aryl groups include, but are not limited to, a phenyl group, a biphenyl group, a terphenyl group, and the like. Polycyclic aryl groups include, but are not limited to, a naphthyl group, anthracenyl group, a phenanthrenyl group, a pyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group, and the like.

[0071] The term "heteroaryl" as used herein refers to an aryl containing at least one of O, N, Si, B, Se, P, and S as a heteroatom, and the number of carbon atoms is not particularly limited, but may be 5 to 20. Examples of heteroaryl include xanthene, thioxanthen, thiophene, furan, pyrrole, imidazole, thiazole, oxazole, oxadiazole, triazole, pyridyl, bipyridyl, pyrimidyl, triazine, acridyl, pyridazine, pyrazinyl, quinolinyl, quinazoline, quinoxalinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, isoquinoline, indole, carbazole, benzoxazole, benzimidazole, benzothiazole, benzocarbazole, benzothiophene, dibenzothiophene, benzofuranyl, phenanthroline, Examples thereof include, but are not limited to, isoxazolyl group, thiadiazolyl group, phenothiazinyl group, and dibenzofuranyl group.

[0072] The term "carbonyl group" as used herein may exist in the form of an aldehyde group (-CHO), a ketone group (-CO-), a carboxyl group (-COOH), an ester group (-COOR), and an amide group (-CONH2). More specific examples include, but are not limited to, a formyl group (-CHO), an acetyl group (-COCH3), and a benzoyl group (-COC6H5).

[0073] The term "alkoxy group" as used herein may be represented by -OR (R is an alkyl group) and may be selected from the group consisting of an alkylalkoxy group, an arylalkoxy group, a heteroarylalkoxy group, an N-alkylalkoxy group, an N-arylalkoxy group, and a polycyclic alkoxy group. The number of substituted carbon atoms is not particularly limited, but may be 1 to 10. More specific examples of alkoxy groups include, but are not limited to, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a phenoxy group, and the like.

[0074] In this specification, the term alkenyloxy group means a functional group in which an alkenyl group (-C=C-) is connected via oxygen (O), and specific examples include, but are not limited to, a vinyloxy group (-OCH=CH2), an allyloxy group (-OCH2CH=CH2), and a butenyloxy group (-OCH2CH=CHCH3).

[0075] The term "carboxyl group" used herein refers to a group in which a carbonyl group (-C=O) and a hydroxyl group (-OH) are bonded, and functions as an organic acid (carboxylic acid). Specific examples include, but are not limited to, formic acid (-HCOOH), acetic acid (-CH3COOH), and benzoic acid (-C6H5COOH).

[0076] The term "carbonate group" in this specification refers to a group in which two oxygen atoms are bonded to a carbonyl group (-C=O), and specific examples include, but are not limited to, dimethyl carbonate and diethyl carbonate.

[0077] The term "sulfonate group" as used herein refers to a functional group having a structure of -SO3R in which a sulfur (S) atom is bonded to three oxygens (O), and exhibits strong hydrophilicity. Specific examples include, but are not limited to, methanesulfonate and benzenesulfonate.

[0078] In this specification, the term "phosphate group" has a structure in which a phosphorus (P) atom is bonded to four oxygen (O), and a specific example is -PO4. 3- , trimethyl phosphate, diethyl phosphate, etc., but are not limited to these.

[0079] As used herein, the term "thiophosphate group" refers to a phosphate group (-PO4 3- ) has a modified structure containing sulfur (S) atoms instead of oxygen (O), and specific examples include, but are not limited to, diethylthiophosphate.

[0080] In this specification, the term “hydroxyl group” refers to a functional group in the form of -OH in which hydrogen (H) is bonded to oxygen (O).

[0081] The term "nitro group" in this specification refers to a functional group having a structure of -NO2 in which a nitrogen (N) atom is bonded to two oxygens (O), and which has a strong electron-withdrawing action.

[0082] The term "ether group" in this specification refers to a group having a structure (-O-) in which an oxygen (O) atom is bonded to two carbon (C) atoms, and can exist as a symmetrical or asymmetrical ether. Ether groups can be divided into simple ethers (RO-R') and cyclic ethers, and specific examples include, but are not limited to, dimethyl ether, diethyl ether, phenyl methyl ether, tetrahydrofuran, and 1,4-dioxane.

[0083] The term "substituted or unsubstituted" as used herein may mean substituted or unsubstituted with one or more groups selected from the group consisting of deuterium, a halogen group, an alkyl group, an alkenyl group, an alkynyl group, a heteroalkyl group, an alkylaryl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an amine group, an alkoxy group, an alkenyloxy group, an alkynyloxy group, a carbonyl group, a carboxyl group, a carbonate group, a sulfonate group, a phosphate group, a thiophosphate group, a hydroxy group, a nitro group, a cyano group, and an ether group.

[0084] In the present invention, the term "alkali metal" means an element belonging to Group 1 of the periodic table, and may include, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), etc.

[0085] In the present invention, the term "alkaline earth metal" means an element belonging to Group 2 of the periodic table, and may include, for example, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), etc.

[0086] In the present invention, the term "transition metal" means an element belonging to Group 3 to Group 12 of the periodic table, and may include, for example, iron (Fe), copper (Cu), nickel (Ni), chromium (Cr), titanium (Ti), platinum (Pt), gold (Au), silver (Ag), etc.

[0087] The term "metalloid" in the present invention refers to an element having properties intermediate between metals and non-metals, and can exhibit electrical conductivity under specific conditions. Examples thereof include boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), etc. In addition, the same symbols throughout the present specification may have the same meaning unless specifically stated otherwise.

[0088] The present invention relates to a compound for an electrolyte, a compound for an electrolyte additive, an electrolyte material, an electrolyte additive, a non-aqueous electrolyte for a secondary battery, and a secondary battery.

[0089] In one embodiment of the present invention, the non-aqueous electrolyte for a secondary battery may include an additive. The additive may include a compound represented by the following chemical formula 1.

[0090] [Chemical Formula 1]

[0091]

[0092] In chemical formula 1,

[0093] R1 is halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 2-10 Alkenyl, substituted or unsubstituted C 2-10 alkynyl, or substituted or unsubstituted C 1-30 It's Amin,

[0094] R2 and R5 are each independently hydrogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, substituted or unsubstituted C 1-10 an alkynyl, or a substituted or unsubstituted cyano group,

[0095] R3 and R4 are each independently hydrogen, or substituted or unsubstituted C 1-10 It is alkyl,

[0096] R6 and R7 are each independently halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, or substituted or unsubstituted C 1-10 It is alkynyl,

[0097] M is at least one metal cation selected from the group consisting of alkali metals, alkaline earth metals, transition metals and metalloids,

[0098] m and n are each independently integers from 1 to 3,

[0099] a is 0 or 1,

[0100] In the above substituted or unsubstituted, substitution means substitution with one or more substituents selected from the group consisting of deuterium, halogen group, alkyl group, alkenyl group, alkynyl group, heteroalkyl group, alkylaryl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, amine group, alkoxy group, alkenyloxy group, alkynyloxy group, carbonyl group, carboxyl group, carbonate group, sulfonate group, phosphate group, thiophosphate group, hydroxy group, nitro group, cyano group, and ether group.

[0101] In one embodiment of the present invention, it is preferable that M is an alkali metal, and in one preferred embodiment, M may be Li.

[0102] In one embodiment of the present invention, the compound represented by the above chemical formula 1 contains a cyano group (-CN), which acts as an electron-withdrawing group (EWG) and can be easily decomposed at a voltage lower than the initial charging voltage, and can form a solid electrolyte interphase (SEI) film that is strong and dense on the surface of the negative electrode. In addition, it can form a positive electrode protective film through chemical bonding between a substituent and the surface of a positive electrode active material such as a transition metal or a transition metal oxide. A protective film in the form of a complex can be formed as a coordination bond is formed due to the donation of an unshared electron pair in the substituent. The formed protective film can suppress side reactions between the electrode active material and the electrolyte solvent, and prevent electrode collapse due to co-intercalation of the electrolyte solvent into the electrode active material. In addition, it can also efficiently function as a movement path (ion tunnel) of lithium ions.

[0103] In one embodiment of the present invention, the compound represented by the chemical formula 1 may be any one of the following compounds:

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] The above compounds can form a more solid and dense solid electrolyte interphase (SEI) film on the cathode surface, and can form a cathode protective film through more efficient chemical bonding with the surface of the cathode active material, such as a substituent and a transition metal or transition metal oxide.

[0114] In one embodiment of the present invention, the electrolyte may further include a compound represented by Chemical Formula 1 and an additional additive. The compound represented by Chemical Formula 1 may be added as a first additive, and a second additive may further be included. The second additive may include at least one selected from the group consisting of a phosphate-based lithium salt compound, a borate-based lithium salt compound, a cyclic carbonate-based compound, a cyclic sultone-based compound, a cyclic sulfate-based compound, a nitrile-based compound, and a silane-based compound. For example, the second additive may include at least one selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), and TMSPi (Tris(trimethylsilyl) Phosphite).

[0115] In one embodiment of the present invention, the additional additive can be included in the electrolyte of a lithium secondary battery to form a stable solid electrolyte interphase (SEI) film on the surface of the negative electrode while minimizing an increase in resistance. Accordingly, by suppressing the decline in the passivation ability of the SEI at high temperatures, the negative electrode can be prevented from deteriorating, and the high-temperature stability and lifespan characteristics of the lithium secondary battery can be significantly improved.

[0116] In one embodiment of the present invention, the additive represented by the above chemical formula 1 and the additional additive may be independently included in an amount of about 0.1 wt% or more based on the total weight of the entire electrolyte, but is not limited thereto, and an appropriate amount may be used as needed within the above content range.

[0117] From this point of view, the content of the additive represented by the above chemical formula 1 is 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%, but any range that does not deteriorate the life characteristics may be used.

[0118] In one embodiment of the present invention, the content of the additional additive is, based on the total weight of the entire electrolyte, 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%, but any range that does not deteriorate the life characteristics may be used.

[0119] If the content of each of the compound represented by the above chemical formula 1 and the additional additive in the entire electrolyte is excessively high, the battery may expand due to excessive gas, thereby reducing the life characteristics.

[0120] Meanwhile, in one embodiment, the secondary battery may be a lithium ion battery, and the electrolyte for the secondary battery may include a lithium salt and a non-aqueous organic solvent.

[0121] In one embodiment of the present invention, the concentration of the lithium salt in the electrolyte may be about 0.01 to 2.0 M, but is not necessarily limited to this range, and an appropriate concentration may be used as needed. Within the above concentration range, further improved battery characteristics can be obtained.

[0122] In one embodiment of the present invention, the lithium salt used in the electrolyte is not particularly limited and any lithium salt that can be used in the art may be used. For example, the lithium salt may include at least one selected from the group consisting of LiPO2F2, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, LiN(CF3SO2)2, LiC4F9SO3, LiAlO2, LiAlCl4, LiC2F6NO4S2, LiCl, LiI, LiSCN, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiPF4(C2O4), LiPF2(C2O4)2, and LiP(C2O4)3.

[0123] In one embodiment of the present invention, the non-aqueous organic solvent may include at least one 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), butylene carbonate, ethyl propionate (EP), ethyl butyrate, acetonitrile (AN), succinonitrile (SN), dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, gamma-valerolactone, gamma-butyrolactone, and tetrahydrofuran, but is not necessarily limited thereto, and any organic solvent that can be used in an organic electrolyte in the relevant technical field may be used.

[0124] In a preferred embodiment of the present invention, the organic solvent may include at least one selected from the group consisting of cyclic carbonates and chain carbonates. The cyclic carbonate may include at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, vinylethylene carbonate, and fluoroethylene carbonate, and the chain carbonate may include at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, and ethyl propyl carbonate.

[0125] In one embodiment of the present invention, the cyclic carbonate can provide advantageous effects in terms of stability and conductivity, and the chain carbonate can provide advantageous effects in terms of fluidity and mixing stability. Furthermore, when the cyclic carbonate and chain carbonate are used in combination, they can contribute to stability and SEI formation, and the chain carbonate can provide complementary electrolyte cores by lowering the viscosity of the electrolyte and thereby increasing ionic conductivity.

[0126]

[0127] In another aspect, the present invention provides a secondary battery including the electrolyte for the secondary battery.

[0128] The secondary battery comprises an electrode assembly including a positive electrode, a negative electrode, and a separator separating the positive electrode and the negative electrode;

[0129] a case accommodating the electrode assembly; and

[0130] The secondary battery electrolyte may be contained within the case and immersed in the electrode assembly.

[0131] The above secondary battery is not particularly limited in its form, and includes, but is not limited to, a lithium ion battery, a lithium ion polymer battery, a lithium sulfur battery, a lithium air battery, etc.

[0132] For example, if the secondary battery is a lithium ion battery, it can be manufactured by the following method.

[0133] First, the anode is prepared.

[0134] For example, a positive electrode active material composition is prepared by mixing a positive electrode active material, a conductive agent, a binder, and a solvent. The positive electrode active material composition is directly coated on a metal current collector to manufacture a positive electrode plate. Alternatively, the positive electrode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on a metal current collector to manufacture a positive electrode plate. The positive electrode is not limited to the forms listed above and may have forms other than those listed above.

[0135] The above-mentioned positive electrode active material is a lithium-containing metal oxide, and any one commonly used in the art can be used without limitation. For example, one or more types of composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used, and specific examples thereof include Li a A 1-b B b D2 (in the above formula, 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above 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 above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Cob B c D α (In the above 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 above equation, 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 above 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 above 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 above equation, 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 above 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 above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Coc Mn d GeO2 (in the above 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 above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (in the above 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) Any compound represented by the chemical formula Fe2(PO4)3(0 ≤ f ≤ 2); LiFePO4 can be used:

[0136] In the chemical formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, 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.

[0137] For example, LiCoO2, LiMn xO 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.

[0138] Of course, it is also possible to use a compound having a coating layer on the surface of the compound, or it is also possible to use a mixture of the compound and a compound having a coating layer. The coating layer may include a coating element compound of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element. The compounds forming these coating layers may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer forming process may use any coating method as long as it can coat the compound with these elements in a method that does not adversely affect the properties of the positive electrode active material (for example, spray coating, dipping, etc.), and since this is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0139] Carbon black, graphite particles, etc. may be used as the above-mentioned conductive material, but are not limited thereto, and any conductive material that can be used in the relevant technical field may be used.

[0140] As the above binder, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene and mixtures thereof, or styrene butadiene rubber polymers may be used, but are not limited thereto, and any binder that can be used in the relevant technical field may be used.

[0141] The solvent may include, but is not limited to, N-methylpyrrolidone, acetone, or water, and any solvent that can be used in the relevant technical field may be used.

[0142] The above contents of the positive electrode active material, conductive agent, binder, and solvent are at levels typically used in lithium ion batteries. Depending on the intended use and configuration of the lithium ion battery, one or more of the conductive agent, binder, and solvent may be omitted.

[0143] Next, the cathode is prepared.

[0144] For example, a negative electrode active material composition is prepared by mixing a negative electrode active material, a conductive agent, a binder, and a solvent. The negative electrode active material composition is directly coated and dried on a metal current collector to produce a negative electrode plate. Alternatively, the negative electrode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on a metal current collector to produce a negative electrode plate.

[0145] The above-mentioned negative electrode active material may be any material that can be used as a negative electrode active material for lithium-ion batteries in the relevant technical field. For example, it may include one or more selected from the group consisting of lithium metal, metals alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials.

[0146] For example, the metal that can be alloyed with the lithium may be Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth element, or a combination thereof, and is not Si), Sn-Y alloy (wherein Y is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth element, or a combination thereof, and is not Sn), etc. The above element Y may 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.

[0147] For example, the transition metal oxide may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like.

[0148] For example, the above non-transition metal oxides are SnO2, SiO x (0 <x<3) 등일 수 있다.

[0149] The carbonaceous material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and the amorphous carbon may be soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, or the like.

[0150] In the negative electrode active material composition, the conductive material and binder may be the same as those used in the positive electrode active material composition.

[0151] The contents of the above negative active material, conductive material, binder, and solvent are at levels typically used in lithium ion batteries. Depending on the intended use and configuration of the lithium ion battery, one or more of the conductive material, binder, and solvent may be omitted.

[0152] Next, a separator that separates the positive and negative electrodes is prepared.

[0153] Any separator commonly used in lithium-ion batteries can be used. A separator with low resistance to ion movement of the electrolyte and excellent electrolyte absorption capacity can be used. For example, a separator selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof may be in the form of a non-woven fabric or a woven fabric. For example, a rollable separator such as polyethylene or polypropylene is used for lithium-ion batteries, and a separator with excellent organic electrolyte absorption capacity can be used for lithium-ion polymer batteries. For example, the separator can be manufactured according to the following method.

[0154] A separator composition is prepared by mixing a polymer resin, a filler, and a solvent. The separator composition may be directly coated and dried on an electrode to form a separator. Alternatively, the separator composition may be cast on a support and dried, and then a separator film peeled from the support may be laminated on an electrode to form a separator.

[0155] The polymer resin used in the manufacture of the above-mentioned separator is not particularly limited, and all materials used as a binder for electrode plates can be used. For example, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or mixtures thereof can be used.

[0156] Next, the electrolyte for the secondary battery described above is prepared.

[0157] Referring to Fig. 1, 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) described above are wound or folded and placed together with a spacer (30), which is supported by a spring (20), and the entire structure is sealed through a gasket (70) to form an electrode assembly, which is accommodated in a case (10, 80). Subsequently, an electrolyte is injected into the case (10, 80), thereby completing the secondary battery (1).

[0158] The above case can have various shapes depending on the purpose of use, design specifications, etc. of the secondary battery, and can be formed to have various sizes and shapes such as a square shape, a thin film shape, and a coin shape.

[0159] For example, the secondary battery may be a coin-type battery. As a specific example, the secondary battery may be a lithium-ion battery.

[0160] A separator may be placed between the positive and negative electrodes to form an electrode assembly. After the electrode assembly is laminated in a bi-cell structure, it is impregnated with an electrolyte, and finally, it is contained and sealed in a pouch, thereby completing a lithium ion polymer battery.

[0161] Additionally, the electrode assemblies are stacked in multiples to form a battery pack, which can be used in any device requiring high capacity and high output. For example, it can be used in laptops, smartphones, electric vehicles, etc.

[0162]

[0163] Hereinafter, the present invention will be described in detail through manufacturing examples, examples, and experimental examples.

[0164] However, the manufacturing examples, examples, and experimental examples described below are only specific examples of one aspect of the present invention, and the present invention is not limited thereto.

[0165]

[0166] Example

[0167] <Synthesis Example 1> Synthesis of Compound 1

[0168] 1-1. Synthesis of intermediate 1

[0169] Ethenesulfonic acid (5.0 g, 0.036 mol) was dissolved in 10 ml of acetone in a reactor, and 3,3'-(methylazanediyl)dipropanenitrile (3.9 g, 0.036 mol) was added dropwise at 0°C, followed by stirring at room temperature for 4 hours. The reaction solution was concentrated and crystallized in methylene chloride / acetone. The solid was filtered and dried under vacuum to obtain 8.3 g.

[0170] 1 H-NMR: (400 MHz, DMSO-d6) d 9.7 (1H, -NH), 6.4 (1H, d), 5.6 (1H, d), 5.2(1H, d), 3.4(4H, t), 3.0 (4H, t), 2.7(3H, s)

[0171] [Intermediate 1]

[0172]

[0173] 1-2. Synthesis of compound 1

[0174] Intermediate 1 (2.72 g, 0.011 mol) and LiPO2F2 (2.4 g, 0.022 mol) were injected into a reactor with 10 ml of acetone under a nitrogen atmosphere, stirred for 24 hours, and then concentrated.

[0175] The concentrate was recrystallized from acetone and methylene chloride, and the solvent was removed to obtain 1.4 g.

[0176] 1 H-NMR: (400 MHz, DMSO-d6) d 10.0 (1H, -NH), 6.48~6.41 (1H, m), 5.65~5.61 (1H, d), 5.30~5.27 (1H, d), 3.48(4H, s), 3.09~3.05 (4H, t), 2.85 (3H, s)

[0177] 19 F-NMR: (400 MHz, DMSO-d6) d -77.90, -80.41

[0178] 31 P-NMR: (400 MHz, DMSO-d6) d -10.49, -16.33, -22.17

[0179] [Compound 1]

[0180]

[0181]

[0182] <Synthesis Example 2> Synthesis of Compound 2

[0183] 2-1. Synthesis of intermediate 2

[0184] Ethenesulfonic acid (1.0 g, 0.009 mol) was dissolved in 10 ml of acetone in a reactor, and 3,3′-iminodipropionitrile (1.14 g, 0.01 mol) was added dropwise at 0°C and stirred for 4 hours. The reaction solution was concentrated and recrystallized from methylene chloride to obtain 2.0 g.

[0185] 1 H-NMR: (400 MHz, DMSO-d6) d 8.98 (1H, -NH2), 6.46~6.40 (1H, m), 5.62~5.58 (1H, d), 5.28~5.25(1H, d),3.32~3.28(4H, t), 2.96~2.92 (4H, t)

[0186] [Intermediate 2]

[0187]

[0188] 2-2. Synthesis of Compound 2

[0189] Intermediate 2 (1.07 g, 0.005 mol) and LiPO2F2 (1.0 g, 0.010 mol) were injected into a reactor with 10 ml of methanol under a nitrogen atmosphere, stirred at 50°C for 12 hours, and then concentrated. The concentrate was recrystallized from acetone and methylene chloride and filtered, obtaining 0.9 g.

[0190] 1 H-NMR: (400 MHz, DMSO-d6) d 8.99(2H, -NH2), 6.47~6.40 (1H, m), 5.63~5.58(1H, d), 5.28~5.25 (1H, d), 3.31~3.28 (4H, t), 2.96~2.92(4H, t)

[0191] 19 F-NMR: (400 MHz, DMSO-d6) d -77.49, -80.01

[0192] 31 P-NMR: (400 MHz, DMSO-d6) d -9.94, -15.79, -21.65

[0193] [Compound 2]

[0194]

[0195]

[0196] <Synthesis Example 3> Synthesis of Compound 3

[0197] 3-1. Synthesis of intermediate 3

[0198] After dissolving prop-2-yne-1-sulfonic acid (2.6 g, 0.022 mol) in 30 ml of acetone in a reactor, 3,3′-iminodipropionitrile (3.0 g, 0.022 mol) was added dropwise at 0°C. After complete addition, the reaction solution was concentrated and recrystallized from methylene chloride to obtain 5.0 g.

[0199] 1 H-NMR: (400 MHz, DMSO-d6) d 8.99 (2H, -NH2), 3.40 (2H, d), 3.33~3.29 (4H, t), 2.99~2.94(4H, t)

[0200] [Intermediate 3]

[0201]

[0202] 3-2. Synthesis of compound 3

[0203] Intermediate 3 (1.27 g, 0.005 mol) and LiPO2F2 (1.0 g, 0.010 mol) were injected into a reactor with 10 ml of methanol under a nitrogen atmosphere, stirred at 50°C for 12 hours, and then concentrated. The concentrate was recrystallized from acetone and methylene chloride and filtered, obtaining 1.8 g.

[0204] 1 H-NMR: (400 MHz, DMSO-d6) d 8.87(2H, -NH2), 3.33~3.32 (2H, d), 3.30~3.27 (4H, t), 2.95~2.88 (5H, m)

[0205] 19 F-NMR: (400 MHz, DMSO-d6) d -77.25, -79.78

[0206] 31 P-NMR: (400 MHz, DMSO-d6) d -9.54, -15.41, -21.28

[0207] [Compound 3]

[0208]

[0209]

[0210] <Synthesis Example 4> Synthesis of Compound 4

[0211] 4-1. Synthesis of intermediate 4

[0212] Trifluoromethanesulfonic acid (18.07 g, 0.12 mol) was dissolved in 100 ml of acetone in a reactor, and 3,3′-iminodipropionitrile (15 g, 0.12 mol) was added dropwise at 0°C and reacted for 4 hours. The reactant was concentrated and recrystallized from methylene chloride to obtain 25 g.

[0213] 1 H-NMR: (400 MHz, DMSO-d6) d 8.93 (2H, -NH2), 3.31~3.28 (4H, t), 2.93~2.91(4H, t)

[0214] 19 F-NMR: (400 MHz, DMSO-d6) d -77.80

[0215] [Intermediate 4]

[0216]

[0217] 4-2. Synthesis of Compound 4

[0218] LiPO2F2 (9.95 g, 0.09 mol) and 100 ml of acetonitrile were mixed in a reactor, and intermediate 4 (12.3 g, 0.045 mol) was added, followed by reaction for 4 hours. The reactant was concentrated, crystallized from methylene chloride, and filtered to obtain 21.1 g.

[0219] 1 H-NMR: (400 MHz, DMSO-d6) d 8.99 (2H, -NH2), 3.31~3.27 (4H, t), 2.94~2.91 (4H, t)

[0220] 19 F-NMR: (400 MHz, DMSO-d6) d -77.69, -77.78, -80.20

[0221] 31 P-NMR: (400 MHz, DMSO-d6) d -10.23, -16.08, -21.93

[0222] [Compound 4]

[0223]

[0224]

[0225] <Manufacturing Example 1> Preparation of electrolyte

[0226] 1.0 M LiPF6 was dissolved in a solvent containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 20:40:40.

[0227] Based on the total weight of the electrolyte (100 wt%), the electrolytes of examples and comparative examples were prepared by adding additives according to Table 1 below. Comparative Example 1 used vinylene carbonate (VC), Comparative Example 2 used LiPO2F2, and Comparative Examples 3 and 4 used the compound of ref. 1 below, to evaluate the performance of the electrolytes including the example compounds of the present invention.

[0228] [ref.1]

[0229]

[0230]

[0231] Classification Additive 1 Concentration of Additive 1 (wt%) Additive 2 Concentration of Additive 2 (wt%) Comparative Example 1 VC 1.0--Comparative Example 2 LiPO 2 F 2 1.0--Comparative Example 3 ref. 10.5--Comparative Example 4 ref. 10.5 VC 1.0 Example 1 Compound 10.5--Example 2 Compound 4 0.5--Example 3 Compound 10.3--Example 4 Compound 10.5--Example 5 Compound 11.0--Example 6 Compound 10.3 VC 1.0 Example 7 Compound 10.5 VC 1.0 Example 8 Compound 11.0 VC 1.0 Example 9 Compound 40.3--Example 10 Compound 40.5--Example 11 Compound 41.0--Example 12 Compound 40.3 VC 1.0 Example 13 Compound 40.5 VC 1.0 Example 14 Compound 41.0 VC 1.0

[0232] <Manufacturing Example 2> Manufacturing of a coin cell

[0233] A slurry of negative active material was prepared by mixing 96 wt% of artificial graphite (S360-L2-H Tiangin BTR New energy technology Co., Ltd.), 1 wt% of SuperP (TIMCAL), 1.5 wt% of styrene-butadiene rubber (SBR) binder (ZEON), and 1.5 wt% of carboxymethyl cellulose (CMC, Sigma-Aldrich), adding the mixture to distilled water, and stirring for 60 minutes using a mechanical stirrer. The slurry was applied to a thickness of about 60 μm on a 30 μm thick copper current collector using a doctor blade, dried in a hot air dryer at 100°C for 1 hour, dried again under vacuum for 8 hours, and then rolled (roll pressed) to prepare a negative electrode plate.

[0234] LiNi 0.6 Mn 0.2 Co 0.2 A slurry of positive electrode active material was prepared by mixing 296 wt% of O2, 2 wt% of conductive agent superP (TIMCAL), and 2% of polyvinylidene fluoride (PVdF, Sigma-Aldrich) in an N-methyl-2-pyrrolidone solvent and stirring for 30 minutes using a mechanical stirrer. The slurry was applied to a thickness of 60 μm on a 20 μm thick aluminum current collector using a doctor blade, dried in a 100°C hot air dryer for 1 hour, dried again for 8 hours under vacuum conditions, and roll pressing to prepare a positive electrode plate.

[0235] A lithium battery was manufactured using 14 μm thick polypropylene as a separator and the organic electrolytes of comparative examples and examples manufactured according to Manufacturing Example 1 as an electrolyte.

[0236]

[0237] <Experimental Example 1> Room Temperature Life Performance Evaluation

[0238] A lithium secondary battery was charged at a constant current of 1.0 C-rate to 4.2 V under constant current / constant voltage (CC / CV) conditions at 25°C, cut-off at 0.05 C-rate while maintaining 4.2 V in constant voltage mode, and then discharged at 1.0 C-rate to 2.7 V. The charge / discharge conditions were defined as one cycle, and the capacity retention rate was measured by repeating the cycle 200 times.

[0239]

[0240] <Experimental Example 2> Evaluation of improved room temperature resistance performance

[0241] The battery manufactured according to the manufacturing example was charged at 1C to 4.2 V, discharged to SOC 50, and then discharged for 10 seconds at four C-rates (0.5, 1, 2, 3 C) to measure the initial direct current resistance (DC-IR). After charging at 1C to 4.2 V and charging / discharging 200 times at room temperature, the DC resistance (DC-IR) was measured in the same manner as the initial DC resistance measurement method.

[0242]

[0243] Evaluation Results

[0244] <Evaluation 1> Evaluation of the resistance increase rate of additive alone

[0245] The resistance increase rates of the electrolytes of Examples 1 and 2, to which Compound 1 and Compound 4 prepared in Synthesis Examples 1 to 4 of the present invention were added, and the resistance increase rates of the electrolytes of Comparative Examples 1 to 3 were compared. The resistance increase rates compared to the initial DC-IR were calculated and expressed as a percentage based on Comparative Example 1. The results are shown in Table 2 below.

[0246] Referring to Table 2, it was confirmed that the resistance increase rates of Examples 1 and 2 of the present invention were reduced by 61% and 44%, respectively, compared to Comparative Example 1. In addition, it was confirmed that the resistance increase rate of Example 1 was reduced by about 54% or more compared to Comparative Example 3, and the resistance increase rate of Example 2 was reduced by 34% or more.

[0247] Compounds 1 and 4 of the present invention are compounds containing a cyano group (-CN), which is an electron-withdrawing group, and when an electron-withdrawing group (EWG) such as a cyano group is present, it can be easily decomposed at a lower voltage than the initial charge to form a solid and dense SEI film on the negative electrode surface. Therefore, it is judged that the resistance increase rate is significantly improved compared to the electrolyte of Comparative Example 3 containing the compound of ref. 1. In addition, the unshared electron pair can chemically combine with the surface of a positive electrode active material such as a transition metal or a transition metal oxide to form a positive electrode protective film, and it is analyzed that this forms a complex-type protective film by forming a coordination bond.

[0248] Additive 1 Concentration of Additive 1 (wt%) Initial resistance Resistance after 200 C. Resistance increase rate (%, based on Comparative Example 1) Comparative Example 1 VC 1.0 17.8 19.4 100 Comparative Example 2 LiPO 2 F 2 1.0 15.5 16.9 104 Comparative Example 3 ref. 10.5 15.3 16.585 Example 1 Compound 10.5 16.3 16.939 Example 2 Compound 40.5 16.3 17.156

[0249]

[0250] <Evaluation 2> Evaluation of capacity retention and resistance increase rate according to the amount of compounds 1 and 4 added

[0251] The capacity retention rate and resistance increase rate of the electrolytes of Examples 3 to 5 and Examples 9 to 11, respectively, prepared according to the addition amounts of compounds 1 and 4 of the present invention, and the electrolytes of Comparative Examples 1 to 3 were compared. The results are shown in FIG. 2, FIG. 3, Table 3, and Table 4.

[0252] Referring to FIG. 2 and Table 3, it was confirmed that the electrolytes of Examples 3 to 5 with compound 1 added exhibited better capacity retention and lower resistance increase rates than those of Comparative Examples 1 to 3 at all concentrations.

[0253] Additive 1 Concentration of Additive 1 (wt%) Capacity retention rate (%) Resistance increase rate (%, based on Comparative Example 1) Comparative Example 1 VC 1.08 9.2100 Comparative Example 2 LiPO 2 F 2 1.08 3.7 104 Comparative Example 3 ref. 10.59 2.285 Example 3 Compound 10.39 4.052 Example 4 Compound 10.59 3.839 Example 5 Compound 11.09 4.57

[0254] Referring to FIG. 3 and Table 4, it was confirmed that the electrolytes of Examples 9 to 11 to which compound 4 was added exhibited better capacity retention and lower resistance increase rates than those of Comparative Examples 1 to 3 at all concentrations.

[0255] Classification Additive 1 Concentration of Additive 1 (wt%) Capacity retention rate (%) Resistance increase rate (%, based on Comparative Example 1) Comparative Example 1 VC 1.08 9.2100 Comparative Example 2 LiPO 2 F 2 1.08 3.7104 Comparative Example 3 ref. 10.59 2.285 Example 9 Compound 40.39 2.758 Example 10 Compound 40.59 2.656 Example 11 Compound 41.09 3.265

[0256]

[0257] <Evaluation 3> Evaluation of capacity retention and resistance increase rate of additive combinations

[0258] The capacity retention rate and resistance increase rate of the electrolyte containing compounds 1 and 4 of the present invention together with additional additives were evaluated. The results are shown in FIG. 4, FIG. 5, Table 5, and Table 6.

[0259] FIG. 4 and Table 5 show the results of comparing the capacity retention rate and resistance increase rate of the electrolytes of Examples 6 to 8, in which Compound 1 was added as an additive 1 and Vinylene Carbonate was added as an additive 2, with those of Comparative Examples 1 and 4. It was confirmed that the electrolytes of Examples 6 to 8, in which Compound 1 and Vinylene Carbonate were added, exhibited better capacity retention rates than Comparative Examples 1 and 4 at all concentrations, and in particular, exhibited significantly lower resistance increase rates. In addition, it was confirmed that Examples 6 to 8 showed improved capacity retention rates and resistance increase rates than Examples 3 to 5, in which Compound 1 was used alone in the above <Evaluation 2>.

[0260] Additive 1Concentration of Additive 1 (wt%)Additive 2Concentration of Additive 2 (wt%)Capacity retention rate (%)Resistance increase rate (%, based on Comparative Example 1)Comparative Example 1VC1.0--89.2100Comparative Example 4ref. 10.5VC1.093.170Example 6Compound 10.3VC1.095.137Example 7Compound 10.5VC1.095.431Example 8Compound 11.0VC1.096.714

[0261] FIG. 5 and Table 6 show the capacity retention rate and resistance increase rate of the electrolytes of Examples 12 to 14, in which compound 4 was added as additive 1 and vinylene carbonate was added as additive 2, compared with those of Comparative Examples 1 and 4. When the electrolytes of Examples 12 to 14 were compared with Comparative Example 4, they showed similar or improved capacity retention rates depending on the concentration. In terms of resistance increase rate, the resistance increase rate was lower than that of Comparative Examples 1 and 4 at all concentrations, and it was confirmed that an excellent improvement effect was shown in terms of resistance increase. In addition, it was confirmed that Examples 12 to 14 showed improved capacity retention rate and resistance increase rate than Examples 9 to 11, in which compound 4 was used alone in the above <Evaluation 2>. Therefore, it is suggested that the compound including a cyano group of the present invention can improve the performance and safety of a battery when included in an electrolyte alone or with an additional additive.

[0262] Additive 1Concentration of Additive 1 (wt%)Additive 2Concentration of Additive 2 (wt%)Capacity retention rate (%)Resistance increase rate (%, based on Comparative Example 1)Comparative Example 1VC1.0--89.2100Comparative Example 4ref. 10.5VC1.093.170Example 12Compound 40.3VC1.093.250Example 13Compound 40.5VC1.093.753Example 14Compound 41.0VC1.094.958

[0263] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0264] The scope of the present invention is indicated by the claims described below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. Lithium salt; non-aqueous organic solvent; and An additive comprising a compound represented by the following chemical formula 1; Non-aqueous electrolyte for secondary batteries: [Chemical Formula 1] In chemical formula 1, R1 is halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 2-10 Alkenyl, substituted or unsubstituted C 2-10 alkynyl, or substituted or unsubstituted C 1-30 It's Amin, R2 and R5 are each independently hydrogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, substituted or unsubstituted C 1-10 an alkynyl, or a substituted or unsubstituted cyano group, R3 and R4 are each independently hydrogen, or substituted or unsubstituted C 1-10 It is alkyl, R6 and R7 are each independently halogen, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkenyl, or substituted or unsubstituted C 1-10 It is alkynyl, M is at least one metal cation selected from the group consisting of alkali metals, alkaline earth metals, transition metals and metalloids, m and n are each independently integers from 1 to 3, a is 0 or 1, In the above substituted or unsubstituted, substitution means substitution with one or more substituents selected from the group consisting of deuterium, halogen group, alkyl group, alkenyl group, alkynyl group, heteroalkyl group, alkylaryl group, cycloalkyl group, heterocycloalkyl group, aryl group, heteroaryl group, amine group, alkoxy group, alkenyloxy group, alkynyloxy group, carbonyl group, carboxyl group, carbonate group, sulfonate group, phosphate group, thiophosphate group, hydroxy group, nitro group, cyano group, and ether group.

2. In paragraph 1, The compound represented by the above chemical formula 1 is any one of the following compounds:

3. In paragraph 1, A non-aqueous electrolyte for a secondary battery, wherein the lithium salt comprises at least one selected from the group consisting of LiPO2F2, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, LiN(CF3SO2)2, LiC4F9SO3, LiAlO2, LiAlCl4, LiC2F6NO4S2, LiCl, LiI, LiSCN, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiPF4(C2O4), LiPF2(C2O4)2, and LiP(C2O4)3.

4. In paragraph 1, A non-aqueous electrolyte for a secondary battery, wherein the additive is contained in an amount of 0.1 wt% to 10 wt% based on the total weight of the electrolyte.

5. In paragraph 1, A non-aqueous electrolyte for a secondary battery, wherein the non-aqueous organic solvent comprises at least one selected from the group consisting of cyclic carbonates and chain carbonates.

6. In paragraph 1, The non-aqueous electrolyte for the secondary battery comprises at least one additional additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), and TMSPi (Tris(trimethylsilyl) Phosphite). Non-aqueous electrolyte for secondary batteries.

7. In paragraph 6, The above additional additive is included in an amount of 0.1 to 10 wt% based on the weight of the non-aqueous electrolyte. Non-aqueous electrolyte for secondary batteries.

8. An electrode assembly including a positive electrode, a negative electrode, and a separator separating the positive electrode and the negative electrode; a case accommodating the electrode assembly; and A lithium secondary battery comprising an electrolyte according to any one of claims 1 to 7, which is accommodated in the case and immerses the electrode assembly.

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