KR20220132283A - Additives for non-aqueous electrolyte, non-aqueous electrolyte comprising the same and lithium secondary battery - Google Patents

Abstract

The present invention relates to an additive for a non-aqueous electrolyte including a sultone-based compound represented by chemical formula 1 capable of improving the lifespan of a lithium secondary battery by forming an electrode-electrolyte interface that is stable and has low resistance even at high temperatures, a non-aqueous electrolyte including the same, and a lithium secondary battery.

Description

Additive for non-aqueous electrolyte, non-aqueous electrolyte and lithium secondary battery containing same

The present invention relates to an additive for a non-aqueous electrolyte containing a sultone-based compound, a non-aqueous electrolyte containing the same, and a lithium secondary battery.

Recently, as personal IT devices and computer networks are developed due to the development of the information society, and the overall society's dependence on electric energy increases accordingly, the development of battery technology for efficiently storing and utilizing electric energy is required.

In particular, as interest in solving environmental problems and realization of a sustainable circulating society has emerged, research on power storage devices such as lithium ion batteries and electric double layer capacitors has been extensively conducted.

In particular, lithium ion batteries are in the spotlight as a battery system with the highest theoretical energy density among battery technologies.

The lithium ion battery is largely composed of a positive electrode composed of a transition metal oxide containing lithium, a negative electrode capable of storing lithium, an electrolyte serving as a medium for transferring lithium ions, and a separator. As it is known as a component that has a great influence on stability, safety, etc., many studies are being conducted on it.

On the other hand, in a lithium secondary battery, as the charging and discharging proceeds, the positive electrode active material structurally collapses due to the decomposition products of lithium salts contained in the electrolyte, and the positive electrode performance may be deteriorated. This can be eluted. The eluted transition metal ions are electro-deposited on the anode or cathode, increasing the anode resistance, degrading the cathode, and destroying the solid electrolyte interphase (SEI), resulting in additional electrolyte decomposition and battery resistance. increase and deterioration of service life.

This deterioration of battery performance tends to be accelerated when the potential of the positive electrode increases or the battery is exposed to high temperatures.

Accordingly, there is an urgent need to study an electrolyte capable of forming a stable SEI film on the electrode surface in order to suppress the elution of transition metal ions from the anode or to prevent deterioration of the cathode.

Japanese Laid-Open Patent Publication No. 2016-0066481 Korean Patent Publication No. 2020-0090223

An object of the present invention is to provide an additive for a non-aqueous electrolyte including a sultone-based additive capable of forming a film that is stable even at high temperatures and has low resistance on the surface of an electrode.

In addition, an object of the present invention is to provide a non-aqueous electrolyte including the additive for a non-aqueous electrolyte.

In addition, the present invention is to provide a lithium secondary battery including the non-aqueous electrolyte.

In order to achieve the above object, the present invention

An additive for a non-aqueous electrolyte is provided, which includes a sultone-based compound represented by the following formula (1).

[Formula 1]

In Formula 1,

Ak ₁ is a direct bond or an alkylene group having 1 to 10 carbon atoms,

Ak ₂ is an alkyl group having 1 to 10 carbon atoms, and n and m are integers of 1 or 2, respectively.

In addition, the present invention provides a non-aqueous electrolyte for a lithium secondary battery comprising the additive for a non-aqueous electrolyte.

In addition, the present invention provides a lithium secondary battery including the non-aqueous electrolyte for a lithium secondary battery.

The sultone-based compound represented by Formula 1 of the present invention has no toxicity and can form a stable film with low resistance on the electrode surface. Accordingly, it is possible to provide a safe manufacturing environment when manufacturing the non-aqueous electrolyte. In particular, the non-aqueous electrolyte including the same forms an electrode-electrolyte interface having a low resistance, so that the transition metal elution from the anode can be effectively controlled. As a result, a lithium secondary battery capable of reducing battery swelling while having excellent high-temperature storage characteristics and high-temperature cycle characteristics can be implemented. The nonaqueous electrolyte of the present invention may be particularly usefully used in a high-output battery used together with a high-capacity active material such as a high-nickel-based positive electrode active material.

The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the above-described content of the invention, so the present invention is limited to the matters described in those drawings It should not be construed as being limited.
1 shows a ¹ H NMR spectrum (acetonitrile-d3) of the compound represented by Formula 1-1 obtained in Preparation Example 1.
2 shows a ¹ H NMR spectrum (acetone-d6) of the compound represented by Formula 1-2 obtained in Preparation Example 2.

Hereinafter, the present invention will be described in more detail.

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In addition, the terminology used herein is used only to describe exemplary embodiments, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

Prior to describing the present invention, in this specification, terms such as "comprises", "comprises" or "have" are not intended to designate the existence of embodied features, numbers, steps, components, or combinations thereof. , it should be understood that it does not preclude the possibility of addition or existence of one or more other features or numbers, steps, elements, or combinations thereof.

Meanwhile, in the description of "carbon number a to b" in the present specification, "a" and "b" mean the number of carbon atoms included in a specific functional group. That is, the functional group may include “a” to “b” carbon atoms. For example, an "alkylene group having 1 to 5 carbon atoms" is an alkylene group containing 1 to 5 carbon atoms, that is, -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, - CH ₂ (CH ₃ )CH—, —CH(CH ₃ )CH ₂ — and —CH(CH ₃ )CH ₂ CH ₂ — and the like.

The term "alkylene group" refers to a branched or unbranched divalent unsaturated hydrocarbon group. In one embodiment, the alkylene group may be substituted or unsubstituted. The alkylene group may include a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, a tert-butylene group, a pentylene group, a 3-pentylene group, and the like.

In addition, in the present specification, unless otherwise defined, "substitution" means that at least one hydrogen bonded to carbon is substituted with an element other than hydrogen, for example, an alkyl group having 1 to 6 carbon atoms or fluorine. means replaced.

Additives for non-aqueous electrolytes

The additive for a non-aqueous electrolyte according to an embodiment of the present invention includes a sultone-based compound represented by the following formula (1). When an additive for a nonaqueous electrolyte including a compound represented by the following Chemical Formula 1 is used, a low resistance and a strong SEI layer is formed, thereby providing a lithium secondary battery having excellent high temperature storage and cycle characteristics.

[Formula 1]

In Formula 1,

Ak ₁ is a direct bond or an alkylene group having 1 to 10 carbon atoms,

Ak ₂ is an alkyl group having 1 to 10 carbon atoms, and n and m are integers of 1 or 2, respectively.

In Formula 1, Ak ₁ may be an alkylene group having 1 to 7 carbon atoms, and Ak ₂ may be an alkyl group having 1 to 7 carbon atoms. Specifically, in Formula 1, Ak ₁ may be an alkylene group having 1 to 4 carbon atoms, and Ak ₂ may be an alkyl group having 1 to 4 carbon atoms.

More specifically, the compound represented by Formula 1 may include at least one of compounds represented by Formulas 1-1 to 1-4 below.

[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

According to an embodiment of the present invention, the sultone-based compound represented by Chemical Formula 1 includes a structure of "-SO ₃ -alkyl group" or "-SO ₄ -alkyl group" as a terminal substituent, thereby having excellent structural stability, 60 It is possible to prevent the compound structure from being decomposed during long-term storage under high-temperature environmental conditions such as ℃. Accordingly, it is possible to provide a non-aqueous electrolyte having excellent high-temperature stability and a secondary battery including the same.

In addition, since the sultone-based compound represented by Formula 1 is reduced faster than the organic solvent in the electrolyte during charging and discharging, a solid SEI may be formed on the electrode surface before side reactions occur.

The reduction stability of these compounds can be evaluated using the Gaussian 09 program package (Gaussian 09 Revision C.01, Gaussian Inc., Wallingford, CT, 2009) to which the DFT calculation method is applied. The evaluation method is to calculate the stable structural energy of the compound in the state before reduction (E _neut ) and the stable structural energy of the compound in the reduced state (E _red ), and then define E _neut - E _red =0.5eV or more as reduction stability. do. At this time, the structural stabilization calculation is performed in a state in which the PCM (Polarizable Continuum Model) method is applied.

According to an embodiment of the present invention, in the compound represented by Formula 1, Ak ₁ is an alkylene group having 10 or less carbon atoms, specifically an alkylene group having 7 or less carbon atoms, more preferably an alkylene group having 4 or less carbon atoms. A more robust SEI film with low resistance can be formed by the number of carbon atoms.

In addition, the compound represented by Formula 1 includes a substituent such as "sulfite group (-SO ₃ -)" or "sulfate group (-SO ₄ -)" in the structure, thereby having low resistance on the surface of the anode and the anode, It is possible to form a film containing a sulfite group or a sulfate group component that is stable even at high temperatures.

As such, the compound represented by Chemical Formula 1 forms an electrode-electrolyte interface with low resistance on the electrode surface by structural characteristics to suppress an increase in interfacial resistance, and also prevents the electrode surface from being exposed to form an electrode-electrolyte interface with the electrode and electrolyte. side reactions can be inhibited. As a result, it is possible to effectively control the elution of transition metals from the positive electrode due to the breakdown of the film, thereby increasing high-temperature stability, and thus implementing a lithium secondary battery capable of reducing battery swelling while having excellent high-temperature storage characteristics and high-temperature cycle characteristics. have.

In the case of 1,3-propane sultone (PS), which is conventionally commercialized as an electrolyte additive, its use is limited due to toxicity, whereas the compound represented by Formula 1 of the present invention has low toxicity, unlike 1,3-propane sultone, Since the synthesis is relatively easy, the effect of reducing the process cost can also be obtained. In addition, since the compound represented by Formula 1 of the present invention has better storage stability than ethylene sulfate, which is known as an electrolyte additive, various side reactions and gas generation caused by using ethylene sulfate can be reduced. As such, the compound represented by Formula 1 of the present invention can be used instead of 1,3-propanesultone or ethylene sulfate, and has the advantage of being able to prepare a non-aqueous electrolyte with improved overall performance and a secondary battery including the same. .

Non-aqueous electrolyte for lithium secondary battery

In addition, the non-aqueous electrolyte according to an embodiment of the present invention includes an additive for a non-aqueous electrolyte including the sultone-based compound represented by Formula 1 above.

The non-aqueous electrolyte may further include a lithium salt, an organic solvent, and other electrolyte additives.

(1) Additives for non-aqueous electrolytes

Since the description of the sultone-based compound represented by Formula 1 overlaps with the above, description thereof will be omitted.

Meanwhile, according to an embodiment of the present invention, the additive for the non-aqueous electrolyte may be included in an amount of 0.01 parts by weight to 10 parts by weight, more specifically, 0.1 parts by weight to 10 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte.

When the content of the additive for non-aqueous electrolyte satisfies the above range, it is possible to effectively suppress the transition metal elution from the anode at high temperature by forming a stable film, thereby realizing excellent high temperature durability. That is, when the additive for the non-aqueous electrolyte is contained in the non-aqueous electrolyte in an amount of 0.01 parts by weight or more, the film-forming effect is improved and a stable SEI film is formed even when stored at a high temperature. can be improved In addition, when the additive for the non-aqueous electrolyte is included in an amount of 10 parts by weight or less, an excessively thick film is prevented from being formed during initial charging to prevent an increase in resistance, thereby preventing a decrease in initial capacity and output characteristics of the secondary battery.

(2) lithium salt

As the lithium salt, those commonly used in electrolytes for lithium secondary batteries may be used without limitation, for example, including Li ⁺ as a cation and F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , B ₁₀ Cl ₁₀ ^- , AlCl ₄ ^- , AlO ₄ ^- , PF ₆ ^- , CF ₃ SO ₃ ^- , CH ₃ CO ₂ ^- , CF ₃ CO ₂ ^- , AsF ₆ ^- , SbF ₆ ^- , CH ₃ SO ₃ ^- , (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , BF ₂ C ₂ O ₄ ^- , BC ₄ O ₈ ^- , PF ₄ C ₂ O ₄ ^- , PF ₂ C ₄ O ₈ ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , C ₄ F ₉ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- and SCN ^- may be at least one selected from the group consisting of.

Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF ₄ , LiClO ₄ , LiB ₁₀ Cl ₁₀ , LiAlCl ₄ , LiAlO ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCH ₃ CO ₂ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiCH ₃ SO ₃ , LiFSI (Lithium bis(fluorosulfonyl) imide, LiN(SO ₂ F) ₂ ), LiBETI (lithium bis(pentafluoroethanesulfonyl) imide, LiN(SO ₂ CF ₂ CF ₃ ) ₂ and LiTFSI (lithium) It may include a single substance or a mixture of two or more selected from the group consisting of bis(trifluoromethanesulfonyl) imide, LiN(SO ₂ CF ₃ ) ₂ ) In addition to these, lithium salts commonly used in electrolytes of lithium secondary batteries can be used without limitation. can

The lithium salt may be appropriately changed within the range that can be used in general, but to be included in the electrolyte at a concentration of 0.8 M to 3.0 M, specifically, at a concentration of 1.0M to 3.0M, in order to obtain an optimal effect of forming a film for preventing corrosion of the electrode surface. can

When the concentration of the lithium salt is less than 0.8 M, the mobility of lithium ions may decrease, and thus capacity characteristics may be deteriorated. When the concentration of the lithium salt exceeds the concentration of 3.0 M, the viscosity of the non-aqueous electrolyte may excessively increase, so that the electrolyte impregnation property may be deteriorated, and the film formation effect may be reduced.

(3) organic solvents

As the organic solvent, various organic solvents commonly used in lithium electrolytes can be used without limitation, and specifically, decomposition by oxidation reaction during the charging and discharging process of secondary batteries can be minimized, and desired properties can be exhibited together with additives. As long as it is possible, there is no limit to its type.

For example, the organic solvent may use a high-viscosity cyclic carbonate-based organic solvent that easily dissociates lithium salts in the electrolyte due to its high dielectric constant. In addition, the organic solvent may be used by mixing a linear carbonate-based organic solvent in an appropriate ratio with the environmental carbonate-based organic solvent in order to prepare an electrolyte having a higher electrical conductivity.

The cyclic carbonate-based organic solvent is a high-viscosity organic solvent that has a high dielectric constant and can well dissociate lithium salts in the electrolyte, and specific examples thereof include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene. At least one organic solvent selected from the group consisting of carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, among them, ethylene carbonate may include.

In addition, the linear carbonate-based organic solvent is an organic solvent having a low viscosity and a low dielectric constant, and representative examples thereof include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate ( EMC), at least one organic solvent selected from the group consisting of methyl propyl carbonate and ethyl propyl carbonate may be used, and specifically, ethyl methyl carbonate (EMC) may be included.

The organic solvent of the present invention may be used by mixing a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, wherein the cyclic carbonate-based organic solvent: the linear carbonate-based organic solvent is 10:90 to 80:20 by volume, specifically 50 It can be used in a volume ratio of :50 to 70:30.

In addition, the organic solvent may further include a linear ester-based organic solvent and/or a cyclic ester-based organic solvent in the cyclic carbonate-based organic solvent and/or the linear carbonate-based organic solvent in order to prepare an electrolyte having high ionic conductivity. may be

Specific examples of the linear ester-based organic solvent include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate and butyl propionate. can be heard

In addition, the cyclic ester-based organic solvent is a specific example of at least one compound selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone and ε-caprolactone Can be used.

Meanwhile, the remainder of the non-aqueous electrolyte of the present invention except for the organic solvent, for example, the non-aqueous electrolyte additive of the present invention, lithium salt, and other additives may be all organic solvents unless otherwise stated.

(4) other additives

On the other hand, the non-aqueous electrolyte according to an embodiment of the present invention is used together with the additive to form a stable film on the surface of the anode and the anode, or to form a stable film on the surface of the anode and the anode without significantly increasing the initial resistance along with the effect expressed by the additive. It may further include other additives capable of inhibiting the decomposition of the solvent and serving as a complement to improve the mobility of lithium ions.

These other additives are not particularly limited as long as they are additives capable of forming a stable film on the surfaces of the positive and negative electrodes.

Specifically, the other additives are representative examples of which include at least one additive selected from the group consisting of a cyclic carbonate-based compound, a halogen-substituted carbonate-based compound, a nitrile-based compound, a phosphate-based compound, a borate-based compound, and a lithium salt-based compound. can

Specifically, the cyclic carbonate-based compound forms a stable SEI film mainly on the surface of the negative electrode during battery activation, thereby improving battery durability. The cyclic carbonate-based compound may include vinylene carbonate (VC) or vinylethylene carbonate, and may be included in an amount of 3 wt% or less based on the total weight of the non-aqueous electrolyte. When the content of the cyclic carbonate-based compound in the non-aqueous electrolyte exceeds 3% by weight, cell swelling inhibition performance and initial resistance may deteriorate.

The halogen-substituted carbonate-based compound may include fluoroethylene carbonate (FEC), and may be included in an amount of 5 wt% or less based on the total weight of the non-aqueous electrolyte. When the content of the halogen-substituted carbonate-based compound exceeds 5% by weight, cell swelling performance may be deteriorated.

In addition, the nitrile-based compound is succinonitrile, adiponitrile (Adn), acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, From the group consisting of 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile at least one or more compounds selected.

The nitrile-based compound may serve as a complement in forming the negative electrode SEI film, may serve to inhibit the decomposition of a solvent in the electrolyte, and may serve to improve the mobility of lithium ions. The nitrile-based compound may be included in an amount of 8 wt% or less based on the total weight of the non-aqueous electrolyte. When the total content of the nitrile-based compound in the non-aqueous electrolyte exceeds 8 wt %, resistance increases due to an increase in a film formed on the surface of the electrode, and battery performance may deteriorate.

In addition, since the phosphate-based compound stabilizes PF ₆ anions in the electrolyte and helps to form positive and negative electrode films, durability of the battery may be improved. These phosphate-based compounds include lithium difluoro(bisoxalato)phosphate (LiDFOP), LiPO ₂ F ₂ , tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(2,2,2-trifluoro and at least one compound selected from the group consisting of roethyl) phosphate and tris(trifluoroethyl) phosphite, and may be included in an amount of 3 wt% or less based on the total weight of the non-aqueous electrolyte.

The borate compound promotes ion pair separation of lithium salts, can improve the mobility of lithium ions, can reduce the interfacial resistance of the SEI film, and materials such as LiF that are generated during battery reaction and are not easily separated By dissociating, problems such as generation of hydrofluoric acid gas can be solved. Such borate-based compounds may include lithium bioxalyl borate (LiBOB, LiB(C ₂ O ₄ ) ₂ ), lithium oxalyldifluoroborate, or tetramethyl trimethylsilylborate (TMSB), based on the total weight of the non-aqueous electrolyte. It may be included in an amount of 3% by weight or less.

In addition, the lithium salt-based compound is a compound different from the lithium salt included in the non-aqueous electrolyte, and may include at least one compound selected from the group consisting of LiODFB and LiBF ₄ , and 3 wt% or less based on the total weight of the non-aqueous electrolyte may include

The other additives may be used in a mixture of two or more, and may be included in an amount of 10 wt% or less, specifically 0.01 wt% to 10 wt%, preferably 0.1 to 5.0 wt%, based on the total amount of the electrolyte.

When the content of the other additives is less than 0.01% by weight, the high temperature storage characteristics and gas reduction effect to be realized from the additives are insignificant, and when the content of the other additives exceeds 10% by weight, side reactions in the electrolyte during charging and discharging of the battery are excessive is likely to occur. In particular, when the other additives are added in excess, they may not be sufficiently decomposed and may exist as unreacted or precipitated substances in the electrolyte at room temperature. Accordingly, resistance may be increased, and thus lifespan characteristics of the secondary battery may be deteriorated.

lithium secondary battery

Next, a lithium secondary battery according to the present invention will be described.

The lithium secondary battery according to the present invention includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to the present invention. Since the non-aqueous electrolyte has been described above, a description thereof will be omitted, and other components will be described below.

(1) Anode

The positive electrode according to the present invention may include a positive electrode active material layer including a positive electrode active material, and if necessary, the positive electrode active material layer may further include a conductive material and/or a binder.

The positive active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically may include a lithium composite metal oxide including lithium and one or more metals such as cobalt, manganese, nickel, or aluminum. have. More specifically, the lithium composite metal oxide may include a lithium-nickel-manganese-cobalt-based oxide represented by the following Chemical Formula 2 in that it can increase the capacity characteristics and stability of the battery.

[Formula 2]

Li(Ni _x Co _y Mn _z )O ₂

(In Formula 2, 0<x<1, 0<y<1, 0<z<1, x+y+z=1)

Specifically, the lithium composite metal oxide may be a lithium composite transition metal oxide having a nickel content of 50 atm% or more, preferably 70 atm% or more in the transition metal, a representative example of which is Li(Ni _0.5 Mn _0.3 Co _0.2 )O ₂ , Li(Ni _0.5 Mn _0.2 Co _0.3 )O ₂ , Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li(Ni _0.7 Mn _0.15 Co _0.15 )O ₂ or Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ .

In addition to the lithium-nickel-manganese-cobalt-based oxide, the cathode active material includes a lithium-manganese-based oxide (eg, LiMnO ₂ , LiMn ₂ O ₄ , etc.), a lithium-cobalt-based oxide (eg, LiCoO ₂ , etc.), Lithium-nickel-based oxide (eg, LiNiO ₂ , etc.), lithium-nickel-manganese oxide (eg, LiNi _1-Y Mn _Y O ₂ (where 0<Y<1), LiMn _2-z Ni _z O ₄ (here, 0<Z<2), etc.), lithium-nickel-cobalt-based oxide (for example, LiNi _1-Y1 Co _Y1 O ₂ (here, 0<Y1<1), etc.), Lithium-manganese-cobalt oxide (for example, LiCo _1-Y2 Mn _Y2 O ₂ (here, 0<Y2<1), LiMn _2-z1 Co _z1 O ₄ (here, 0<Z1<2), etc.) ), or lithium-nickel-cobalt-transition metal (M) oxide (eg, Li(Ni _p2 Co _q2 Mn _r3 M _S2 )O ₂ , where M is Al, Fe, V, Cr, Ti, Ta , Mg and Mo, p2, q2, r3 and s2 are each independent atomic fractions of elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s 2 < 1, p2+q2+r3+s2=1)) and the like, and any one or two or more compounds of these may be included.

Such a positive active material may be LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , or lithium nickel cobalt aluminum oxide (eg, Li(Ni _0.8 Co _0.15 Al _0.05 )O ₂ , etc.).

The positive active material may be included in an amount of 90 wt% to 99 wt%, specifically 93 wt% to 98 wt%, based on the total weight of the solid content in the cathode active material layer.

The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and for example, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black. carbon powder; Graphite powder, such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the solid content in the positive electrode active material layer.

The binder is a component serving to improve adhesion between the positive active material particles and adhesion between the positive active material and the current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the solid content in the positive active material layer. Examples of the binder include a fluororesin-based binder including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); Styrene-butadiene rubber (styrene butadiene rubber, SBR), acrylonitrile-butadiene rubber, styrene-rubber-based binder including isoprene rubber; Cellulose binders including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; a polyalcohol-based binder comprising polyvinyl alcohol; Polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester binder; and silane-based binders.

The positive electrode of the present invention as described above may be manufactured according to a method for manufacturing a positive electrode known in the art. For example, in the positive electrode, a positive electrode slurry prepared by dissolving or dispersing a positive electrode active material, a binder and/or a conductive material in a solvent is applied on a positive electrode current collector, followed by drying and rolling to form a positive electrode active material layer; Alternatively, the positive electrode active material layer may be cast on a separate support, and then a film obtained by peeling the support may be prepared by laminating on a positive electrode current collector.

The positive electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. , nickel, titanium, silver or the like surface-treated may be used.

The solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount having a desirable viscosity when the positive active material and optionally a binder and a conductive material are included. For example, it may be included so that the solid content concentration in the active material slurry including the positive active material and, optionally, the binder and the conductive material is 10 wt% to 70 wt%, preferably 20 wt% to 60 wt%.

(2) cathode

Next, the cathode will be described.

The negative electrode according to the present invention includes an anode active material layer including an anode active material, and the anode active material layer may further include a conductive material and/or a binder, if necessary.

The negative active material is lithium metal, a carbon material capable of reversibly intercalating/deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium; and at least one selected from the group consisting of transition metal oxides and transition metal oxides.

As a carbon material capable of reversibly intercalating/deintercalating lithium ions, any carbon-based negative active material generally used in lithium ion secondary batteries may be used without particular limitation, and representative examples thereof include crystalline carbon, Amorphous carbon or these may be used together. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low temperature calcined carbon). or hard carbon, mesophase pitch carbide, and calcined coke.

Examples of the above metals or alloys of these metals and lithium include Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al. And a metal selected from the group consisting of Sn or an alloy of these metals and lithium may be used.

Examples of the metal composite oxide include PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ . , Bi ₂ O ₅ , Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), and Sn _x Me _1-x Me′ _y O _z (Me: Mn, Fe , Pb, Ge; Me': Al, B, P, Si, elements of Groups 1, 2, and 3 of the periodic table, halogen; 0<x≤1;1≤y≤3; 1≤z≤8) One selected from the group may be used.

Examples of the material capable of doping and dedoping lithium include Si, SiO _x (0<x≤2), Si-Y alloy (wherein Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, An element selected from the group consisting of rare earth elements and combinations thereof, but not Si), Sn, SnO ₂ , Sn-Y (wherein Y is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth) It is an element selected from the group consisting of elements and combinations thereof, and is not Sn) and the like. Also, at least one of these and SiO ₂ may be mixed and used. As the element Y, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db (dubnium), 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, and combinations thereof.

Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide.

The anode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the solid content in the anode active material layer.

The conductive material is a component for further improving the conductivity of the anode active material, and may be added in an amount of 1 to 20 wt% based on the total weight of the solid content in the anode active material layer. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the solid content in the negative active material layer. Examples of the binder include a fluororesin-based binder including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); Styrene-butadiene rubber (styrene butadiene rubber, SBR), acrylonitrile-butadiene rubber, styrene-rubber-based binder including isoprene rubber; Cellulose binders including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; a polyalcohol-based binder comprising polyvinyl alcohol; Polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester binder; and silane-based binders.

The negative electrode may be manufactured according to a method for manufacturing a negative electrode known in the art. For example, the negative electrode is a method of forming a negative electrode active material layer by applying a negative electrode active material slurry prepared by dissolving or dispersing a negative electrode active material and optionally a binder and a conductive material in a solvent on the negative electrode current collector, rolling and drying the negative electrode active material layer, or It can be prepared by casting the anode active material layer on a separate support and then laminating a film obtained by peeling the support on the anode current collector.

The negative electrode current collector generally has a thickness of 3 to 500 μm. Such a negative current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel. The surface treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. may be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and may be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven body, and the like.

The solvent may include water or an organic solvent such as NMP, alcohol, or the like, and may be used in an amount to achieve a desirable viscosity when the negative electrode active material and, optionally, a binder and a conductive material are included. For example, it may be included so that the concentration of solids in the active material slurry including the negative active material and, optionally, the binder and the conductive material is 50 wt% to 75 wt%, preferably 50 wt% to 65 wt%.

(3) separator

The lithium secondary battery according to the present invention includes a separator between the positive electrode and the negative electrode.

The separator separates the anode and the cathode and provides a passage for lithium ions to move, and can be used without any particular limitation as long as it is normally used as a separator in a lithium secondary battery. It is preferable that this is excellent.

Specifically, as a separator, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer. Alternatively, a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, in order to secure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material may be used, and may optionally be used in a single-layer or multi-layer structure.

The lithium secondary battery according to the present invention as described above can be usefully used in portable devices such as mobile phones, notebook computers, digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

The battery module or battery pack is a power tool (Power Tool); electric vehicles, including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Alternatively, it may be used as a power source for any one or more medium and large-sized devices in a system for power storage.

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape using a can, a prismatic shape, a pouch type, or a coin type.

The lithium secondary battery according to the present invention can be used not only in a battery cell used as a power source for a small device, but can also be preferably used as a unit cell in a medium or large battery module including a plurality of battery cells.

Hereinafter, the present invention will be described in detail by way of Examples.

At this time, the embodiment according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiment described in detail below. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

production example

Preparation Example 1. Synthesis of the compound represented by Formula 1-1

(5-(hydroxymethyl)-1,2-oxathiolane-2,2-dioxide (5-(hydroxymethyl)-1,2-oxathiolane-2,2-dioxide) synthesis)

30 g (160 mmol, content: 90%) of sodium 2,3-dihydroxybutanesulfonate was suspended in 200 mL of toluene, and then 0.58 g (10 mmol, manufactured by Aldrich) of N,N-dimethylformamide (DMF) was added. Thereafter, 37.57 g (320 mmol, manufactured by Aldrich) of thionyl chloride was added dropwise dropwise, followed by heating and stirring at 65°C for 7 hours.

Then, the reaction solution was cooled to room temperature, methanol 50 g (1.57 mol, manufactured by Aldrich) was added to the cooled solution, and the mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution was concentrated under reduced pressure, and then 50 mL of ethyl acetate and 30 mL of water were added to the resulting concentrate, followed by stirring.

Then, the organic layer was separated, washed with water, concentrated again, and then toluene was added to the concentrate, and the resulting crystals were filtered, and the white crystals of 5-(hydroxymethyl)- represented by formula (IV)- 20 g of 1,2-oxathiorane-2,2-dioxide (yield: 83%) was obtained.

(Synthesis of the compound of formula 1-1)

10 g of 5-(hydroxymethyl)-1,2-oxathioran-2,2-dioxide represented by the above formula (IV) was placed in a 250 mL round flask, 100 mL of dimethyl carbonate was added to dissolve, and then pyridine 5.98 g and SOCl ₂ 8.60 g were added and stirred at room temperature (25° C.) for 1 hour.

Then, 3.48 g of ethanol was added to the reaction mixture and stirred for an additional 1 hour.

After completion of the reaction, ethyl acetate was added, and the resulting reactant was filtered to obtain 15 g of a compound represented by Formula 1-1 (yield: 97%). Whether the compound represented by Formula 1-1 was synthesized or purified was confirmed through the ¹ H NMR spectrum of FIG. 1 (Bruker, AVANCE NEO, 500 MHz, Acetonitrile-d3).

Preparation Example 2. Synthesis of a compound represented by Formula 1-2

15 g of the compound represented by Formula 1-1 obtained in Preparation Example 1 was placed in a round flask, 100 mL of a mixture of acetonitrile and water (1:1 volume ratio) was added to dissolve, and then NaIO ₄ 13.13 g and RuCl ₃ 0.1 g was added, and the mixture was further stirred for 1 hour.

After completion of the reaction, ethyl acetate was added, the organic layer was separated, washed with water, and then concentrated again to obtain 19 g of a compound represented by Formula 1-2 (yield: 98%). Whether the compound represented by Formula 1-2 was synthesized or purified was confirmed through ¹ H NMR spectrum (Bruker, AVANCE NEO, 500 MHz, Acetone-d6) of FIG. 2 .

Example

Example 1.

(Manufacture of non-aqueous electrolyte)

Ethylene carbonate (EC): ethyl methyl carbonate (EMC) was dissolved in 99 g of a non-aqueous organic solvent mixed in a volume ratio of 30:70 so that LiPF ₆ was 1.0M, and 1.0 g of the compound represented by Formula 1-1 was added as an additive. to prepare a non-aqueous electrolyte (see Table 1 below).

(anode manufacturing)

The positive active material (Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ ), the conductive material (carbon black), and the binder (polyvinylidene fluoride) are mixed with a solvent in a weight ratio of 97.5:1:1.5 by weight of N-methyl-2-pyrroly It was added to Don (NMP) to prepare a positive electrode active material slurry (solid content concentration of 60% by weight). The positive electrode active material slurry was applied and dried on a positive electrode current collector (Al thin film) having a thickness of 15 μm, and then a roll press was performed to prepare a positive electrode.

(cathode manufacturing)

A negative active material slurry (solids concentration of 50% by weight) was prepared by adding a negative active material (graphite), a conductive material (carbon black), and a binder (polyvinylidene fluoride) to distilled water in a weight ratio of 96:0.5:3.5. The negative electrode active material slurry was applied and dried on a negative electrode current collector (Cu thin film) having a thickness of 8 μm, and then a roll press was performed to prepare a negative electrode.

(Secondary battery manufacturing)

The positive electrode and the negative electrode prepared by the above method were laminated together with a polyethylene porous film as a separator to prepare an electrode assembly, and then put it in a battery case, inject the non-aqueous electrolyte, and seal the pouch-type lithium secondary battery (battery capacity 6.24 mAh). ) was prepared.

Example 2.

Except for preparing a non-aqueous electrolyte by dissolving LiPF ₆ in 99 g of a non-aqueous organic solvent so as to become 1.0 M, and then adding 1.0 g of a compound represented by Formula 1-2 as an additive (see Table 1 below), the above Example A pouch-type lithium secondary battery was manufactured in the same manner as in 1 .

Example 3.

Except for preparing a non-aqueous electrolyte by dissolving LiPF ₆ in 97 g of a non-aqueous organic solvent so that 1.0 M becomes 1.0 M, and then adding 3.0 g of a compound represented by Formula 1-2 as an additive (see Table 1 below), the above Example A pouch-type lithium secondary battery was manufactured in the same manner as in 1 .

Comparative Example 1.

A lithium secondary battery was prepared in the same manner as in Example 1, except that LiPF ₆ was dissolved in 97 g of a non-aqueous organic solvent so as to become 1.0 M, and a non-aqueous electrolyte was prepared without adding an additive (see Table 1 below). did.

Comparative Example 2.

Except for preparing a non-aqueous electrolyte by dissolving LiPF ₆ in 99 g of a non-aqueous organic solvent so as to become 1.0 M and adding 1.0 g of 1,3-propane sultone as an additive (see Table 1 below), Example 1 and A lithium secondary battery was manufactured in the same manner.

organic solvent additive composition Addition (g) type Added amount (g) Example 1 0.1M LiPF ₆ EC:EMC= 30:70 99 Formula 1-1 One Example 2 99 Formula 1-2 One Example 3 97 Formula 1-2 3 Comparative Example 1 100 - - Comparative Example 2 99 PS One

[Experimental example]

Experimental Example 1. Evaluation of volume change rate during storage at high temperature (60° C.)

The secondary batteries prepared in Examples 1 to 3 and the secondary batteries prepared in Comparative Examples 1 and 2 were each activated at 0.1C CC. Then, using a PESC05-0.5 charger/discharger (manufacturer: PNE Solution, 5V, 500 mA) at 25°C, it was charged at 0.33C CC up to 4.2V under constant current-constant voltage (CC-CV) charging conditions, followed by a 0.05 C Current cut was performed, and discharged at 0.33 C up to 2.5 V under CC conditions. The charging and discharging were performed as 1 cycle, and 2 cycles were performed. Then, it was fully charged with 0.33 C/4.2V constant current-constant voltage, discharged at SOC 50% at 2.5C for 10 seconds, and the initial resistance was calculated through the voltage difference between the voltage before discharging for 10 seconds and the voltage after discharging for 10 seconds.

Then, it was discharged with a constant current of 0.33 C until it became 2.5V. Subsequently, degassing was performed, and the initial volume was measured by putting the initially charged and discharged lithium secondary battery into a bowl filled with water at room temperature using TWD-150DM equipment from Two-pls. Then, the lithium secondary battery was fully charged at 0.33 C/4.2 V constant current-constant voltage, respectively, and stored at 60° C. for 4 weeks (SOC (state of charge) 100%), followed by Two-pls company, TWD-150DM equipment The lithium secondary battery was put into a bowl filled with water at room temperature using

The volume change rate (%) was calculated by substituting the initial volume measured as described above and the volume after high-temperature storage into Equation (1) below, and the results are shown in Table 2 below.

[Equation 1]

Volume change rate (%) = {(Volume after 4 weeks of high-temperature storage-initial volume)/(initial volume)}×100

Experimental Example 2. Evaluation of resistance increase rate after storage at high temperature (60 ℃)

The secondary batteries prepared in Examples 1 to 3 and the secondary batteries prepared in Comparative Examples 1 and 2 were each activated at 0.1C CC. Then, using a PESC05-0.5 charger/discharger (manufacturer: PNE Solution, 5V, 500 mA) at 25°C, it was charged at 0.33C CC up to 4.2V under constant current-constant voltage (CC-CV) charging conditions, followed by a 0.05 C Current cut was performed, and discharged at 0.33 C up to 2.5 V under CC conditions. The charging and discharging were performed as 1 cycle, and 2 cycles were performed. Then, it was fully charged with 0.33 C/4.2V constant current-constant voltage, discharged at SOC 50% at 2.5C for 10 seconds, and the initial resistance was calculated through the voltage difference between the voltage before discharging for 10 seconds and the voltage after discharging for 10 seconds.

Then, it was discharged with a constant current of 0.33 C until it became 2.5V. Then, degassing was performed, each charged to 4.2 V, stored at 60° C. for 4 weeks (SOC (state of charge) 100%), and then discharged again at SOC 50% to 2.5 C for 10 seconds, resistance after high-temperature storage was measured.

The resistance increase rate (%) was calculated by substituting the initial resistance value measured as described above and the resistance value after high temperature storage into Equation (2) below, and the results are shown in Table 2 below.

[Equation 2]

Resistance increase rate (%) = {(resistance value after 4 weeks of high temperature storage - initial resistance value)/(initial resistance value} x 100

Volume change rate (%) Resistance increase rate (%) Example 1 13 7 Example 2 8 13 Example 3 10 17 Comparative Example 1 37 45 Comparative Example 2 25 40

As shown in Table 2, looking at the high-temperature storage characteristics, in the case of the secondary batteries prepared in Examples 1 to 3, compared to the secondary batteries prepared in Comparative Examples 1 and 2, it can be confirmed that the rate of change in volume and the rate of increase in resistance are improved. . This characteristic seems to be due to the increase in the stability of the secondary batteries of Examples 1 to 3 as the SEI film having high stability and low resistance is efficiently formed by the additive represented by the formula (1).

Accordingly, when the compound represented by Formula 1 according to an embodiment of the present invention is used as an additive for a non-aqueous electrolyte, a lithium secondary battery having excellent high-temperature storage characteristics can be provided.

Experimental Example 3. Evaluation of cycle characteristics at high temperature (45°C)

The secondary batteries prepared in Examples 1 to 3 and the secondary batteries prepared in Comparative Examples 1 and 2 were each activated at 0.1 C CC. Then, using a PESC05-0.5 charger/discharger (manufacturer: PNE Solution, 5V, 500 mA) at 25°C, it was charged at 0.33C CC up to 4.2V under constant current-constant voltage (CC-CV) charging conditions, followed by a 0.05 C Current cut was performed, and discharged at 0.33 C up to 2.5 V under CC conditions. The charging and discharging were performed as 1 cycle, and 2 cycles were performed. Then, it was fully charged with 0.33 C/4.2V constant current-constant voltage, discharged at SOC 50% at 2.5C for 10 seconds, and the initial resistance was calculated through the voltage difference between the voltage before discharging for 10 seconds and the voltage after discharging for 10 seconds.

Then, it was discharged with a constant current of 0.33 C until it became 2.5V. Then, the degassing is carried out, respectively, under the conditions of 2.5 V to 4.2 V, respectively, under the conditions of 45 ° C., at 0.33 C, with a constant current, until 4.2 V, and then with a constant voltage of 4.2 V. When the charging current becomes 0.05 C Charging was terminated. Then, after leaving it for 20 minutes, it was discharged with a constant current of 0.33C until it became 2.5 V. 100 cycles of charging and discharging were performed by making the said charging/discharging cycle 1 cycle.

At this time, the capacity after the first cycle and the capacity after the 100th cycle are measured using a PESC05-0.5 charger/discharger (manufacturer: PNE Solution, 5V, 500 mA), and the capacity retention rate is measured by substituting the capacity into the following formula (3) did. The results are shown in Table 3 below.

[Equation 3]

Capacity retention rate (%) = (capacity after 100 cycles / capacity per cycle)×100

On the other hand, 100 cycles were performed, and then the resistance after 100 cycles was calculated by discharging at SOC 50% to 2.5 C for 10 seconds, and then using the voltage difference between the voltage before discharging for 10 seconds and the voltage after discharging for 10 seconds.

The resistance increase rate was measured by substituting the initial resistance value measured as described above and the resistance value after 100 cycles into Equation (4) below. The results are shown in Table 3 below.

[Equation 4]

Resistance increase rate (%) = {(resistance value after 100 cycles - initial resistance value)/initial resistance value}×100

after 100 cycles
Capacity retention rate (%) after 100 cycles
Resistance increase rate (%) Example 1 92 11 Example 2 94 14 Example 3 89 15 Comparative Example 1 78 40 Comparative Example 2 85 24

As shown in Table 3, looking at the cycle characteristic evaluation results, in the case of the secondary batteries prepared in Examples 1 to 3, the capacity retention rate was improved compared to the secondary batteries prepared in Comparative Examples 1 and 2, and the resistance increase rate was improved. it can be seen that This characteristic seems to be due to the increased stability of the secondary batteries of Examples 1 to 3 as the SEI film having high stability and low resistance is efficiently formed by the additive represented by Formula 1 .

Accordingly, it can be seen that, when the compound represented by Formula 1 according to an embodiment of the present invention is used as an additive for a non-aqueous electrolyte, a lithium secondary battery having excellent high-temperature cycle characteristics can be provided.

Claims (10)

An additive for a non-aqueous electrolyte comprising a sultone-based compound represented by the following formula (1):
[Formula 1]

In Formula 1,
Ak ₁ is a direct bond or an alkylene group having 1 to 10 carbon atoms,
Ak ₂ is an alkyl group having 1 to 10 carbon atoms,
n and m are each an integer of 1 or 2.
The method according to claim 1,
In Formula 1, Ak ₁ is an alkylene group having 1 to 7 carbon atoms, and Ak ₂ is an alkyl group having 1 to 7 carbon atoms.
The method according to claim 1,
In Chemical Formula 1, Ak ₁ is an alkylene group having 1 to 4 carbon atoms, and Ak ₂ is an alkyl group having 1 to 4 carbon atoms.
The method according to claim 1,
The compound represented by Formula 1 is at least one of the compounds represented by Formulas 1-1 to 1-4 below.
[Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Formula 1-4]

A non-aqueous electrolyte for a lithium secondary battery comprising the additive for a non-aqueous electrolyte of claim 1.
6. The method of claim 5,
The additive for the non-aqueous electrolyte is a non-aqueous electrolyte for a lithium secondary battery that is included in an amount of 0.01 parts by weight to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte for a lithium secondary battery.
6. The method of claim 5,
The additive for the non-aqueous electrolyte is a non-aqueous electrolyte for a lithium secondary battery that is included in an amount of 0.1 parts by weight to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte for a lithium secondary battery.
6. The method of claim 5,
The non-aqueous electrolyte for a lithium secondary battery further comprises a lithium salt and an organic solvent.
6. The method of claim 5,
The non-aqueous electrolyte for a lithium secondary battery further comprises at least one other additive selected from the group consisting of a cyclic carbonate-based compound, a halogen-substituted carbonate-based compound, a nitrile-based compound, a phosphate-based compound, a borate-based compound, and a lithium salt-based compound Non-aqueous electrolyte for phosphorus lithium secondary batteries.
anode; cathode; a separator interposed between the negative electrode and the positive electrode; and
A lithium secondary battery comprising the non-aqueous electrolyte for a lithium secondary battery of claim 5.

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