KR20240073637A - Non-aqueous electrolyte and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a lithium salt; organic solvent; and an additive, wherein the additive includes a compound represented by a specific chemical formula. The non-aqueous electrolyte according to the present invention can improve the high-temperature durability and life performance of the battery, and at the same time improve heat generation characteristics control and thermal safety.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same {NON-AQUEOUS ELECTROLYTE AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME}

The present invention relates to a non-aqueous electrolyte and a lithium secondary battery containing the same.

Recently, the application area of lithium secondary batteries has rapidly expanded not only to supply power to electronic devices such as electricity, electronics, communication, and computers, but also to supply power storage to large-area devices such as automobiles and power storage devices. Demand for stable secondary batteries is increasing.

Lithium secondary batteries are generally made of a mixture of positive electrode active materials such as lithium-containing transition metal oxides or negative electrode active materials such as carbon-based active materials and silicon-based active materials that can occlude and release lithium ions, and optionally a binder and a conductive material. It is manufactured by applying it to the positive electrode current collector and the negative electrode current collector to manufacture the positive electrode and negative electrode, stacking them on both sides of the separator to form an electrode current collector of a predetermined shape, and then inserting this electrode current collector and non-aqueous electrolyte into the battery case. . In order to secure the performance of the battery, it almost inevitably goes through formation and aging processes.

The formation process is a step of activating the secondary battery by repeating charging and discharging after battery assembly. During the charging, lithium ions from the positive electrode active material used as the positive electrode move and are inserted into the negative electrode active material used as the negative electrode. At this time, highly reactive lithium ions react with the electrolyte to generate compounds such as Li ₂ CO ₃ , Li ₂ O, and LiOH, and these compounds form a solid electrolyte interface (SEI film) layer on the electrode surface. .

The SEI film is an important factor that closely affects lifespan and capacity maintenance. In particular, when stored at high temperatures, the SEI film gradually collapses, which may cause problems such as electrode exposure, so it is necessary to develop additives in the electrolyte that help create an SEI film that can suppress side reactions when stored at high temperatures.

In addition, non-aqueous electrolytes have the disadvantage of low safety due to combustion due to increases in ambient temperature and the temperature of the battery itself. Therefore, there is a demand for the development of non-aqueous electrolytes for lithium secondary batteries that compensate for these disadvantages and ensure both performance and safety.

One object of the present invention is to provide a non-aqueous electrolyte that can improve the high-temperature durability and life performance of a battery, and at the same time control heat generation characteristics and improve thermal safety.

In addition, another object of the present invention is to provide a lithium secondary battery containing the above-described non-aqueous electrolyte.

The present invention relates to a lithium salt; organic solvent; and an additive, wherein the additive includes at least one selected from the group consisting of compounds represented by Formulas 1 to 4 below.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 1 to 4, R ₁ to R ₄ are independently selected from an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms with one or more fluorine substituted, an aryl group with 6 to 30 carbon atoms, and an alkyl group with one or more fluorine substituted. It is selected from aryl groups having 6 to 30 carbon atoms, and L ₁ to L ₄ are independently selected from a direct bond, -COO-, and -SO ₂ -.

In addition, the present invention provides a positive electrode including a positive electrode active material; A negative electrode containing a negative electrode active material; a separator interposed between the anode and the cathode; It provides a lithium secondary battery comprising the above-mentioned non-aqueous electrolyte.

The non-aqueous electrolyte of the present invention is characterized by containing a cyclic phospholane compound in which a specific substituent is substituted for phosphorus (P) as an additive. The additive enables the formation of an SEI film with excellent high-temperature durability on the anode/cathode, thereby improving battery life performance, controlling heat generation of the battery, and ensuring safety.

Therefore, a lithium secondary battery containing the above-described non-aqueous electrolyte has excellent life performance and resistance characteristics at high temperatures, and thermal safety can be improved.

Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It should be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is.

In this specification, terms such as “comprise,” “comprise,” or “have” are intended to designate the presence of implemented features, numbers, steps, components, or a combination thereof, but are intended to indicate the presence of one or more other features or numbers. It should be understood that this does not exclude in advance the possibility of the presence or addition of steps, components, or combinations thereof.

Meanwhile, before explaining the present invention, unless otherwise specified in the present invention, "*" means a connected portion (bonding site) between terminal parts of the same or different atoms or chemical formulas.

In addition, in the description of “carbon numbers a to b” in this specification, “a” and “b” refer to 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, “alkyl group having 1 to 5 carbon atoms” refers to an alkyl group containing 1 to 5 carbon atoms, i.e. CH ₃ -, CH ₃ CH ₂ -, CH ₃ CH ₂ CH ₂ -, (CH ₃ ) ₂ CH -, CH ₃ CH ₂ CH ₂ CH ₂ -, (CH ₃ ) ₂ CHCH ₂ -, CH ₃ CH ₂ CH ₂ CH ₂ CH ₂ -, (CH ₃ ) ₂ CHCH ₂ CH ₂ -, etc.

Additionally, in the present specification, the alkyl group, alkenyl group, or alkynyl group may all be substituted or unsubstituted. Unless otherwise defined, the term "substitution" means that at least one hydrogen bonded to carbon is replaced with an element other than hydrogen, for example, an alkyl group with 1 to 20 carbon atoms, an alkene with 2 to 20 carbon atoms. Nyl group, alkynyl group of 2 to 20 carbon atoms, alkoxy group of 1 to 20 carbon atoms, cycloalkyl group of 3 to 12 carbon atoms, cycloalkenyl group of 3 to 12 carbon atoms, cycloalkynyl group of 3 to 12 carbon atoms, hetero group of 3 to 12 carbon atoms Cycloalkyl group, heterocycloalkenyl group with 3 to 12 carbon atoms, heterocycloalkynyl group with 2 to 12 carbon atoms, aryloxy group with 6 to 12 carbon atoms, halogen atom, fluoroalkyl group with 1 to 20 carbon atoms, nitro group, 6 to 12 carbon atoms It means substituted with an aryl group of 20, a heteroaryl group of 2 to 20 carbon atoms, a haloaryl group of 6 to 20 carbon atoms, etc.

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

non-aqueous electrolyte

The present invention relates to non-aqueous electrolytes. More specifically, the non-aqueous electrolyte may be a non-aqueous electrolyte for a lithium secondary battery.

The non-aqueous electrolyte according to the present invention provides a non-aqueous electrolyte wherein the additive includes at least one selected from the group consisting of compounds represented by the following formulas 1 to 4.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 1 to 4, R ₁ to R ₄ are independently selected from an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms with one or more fluorine substituted, an aryl group with 6 to 30 carbon atoms, and an alkyl group with one or more fluorine substituted. It is selected from aryl groups having 6 to 30 carbon atoms, and L ₁ to L ₄ are independently selected from a direct bond, a direct bond, -COO-, and -SO ₂ -.

The non-aqueous electrolyte of the present invention is characterized by containing, as an additive, a cyclic phospholane compound in which the above-described substituent is substituted for phosphorus (P). The additive enables the formation of an SEI film with excellent high-temperature durability on the anode/cathode, thereby improving battery life performance, controlling heat generation of the battery, and ensuring safety. Therefore, a lithium secondary battery containing the above-described non-aqueous electrolyte has excellent life performance and resistance characteristics at high temperatures, and thermal safety can be improved.

(1) Lithium salt

As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries can be used without limitation. For example, the lithium salt includes Li ⁺ as a cation, and F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , and ClO ₄ ^- as anions. , AlO ₄ ^- , AlCl ₄ ^- , PF ₆ ^- , SbF ₆ ^- , AsF ₆ ^- , B ₁₀ Cl ₁₀ ^- , 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 ^- , CF ₃ SO ₃ ^- , C ₄ F ₉ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , (FSO ₂ ) ₂ N ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , CH ₃ SO ₃ ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- selected from the group consisting of It may include at least one of them.

Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF ₄ , LiClO ₄ , LiAlO ₄ , LiAlCl ₄ , LiPF ₆ , LiSbF ₆ , LiAsF ₆ , LiB ₁₀ Cl ₁₀ , LiBOB (LiB(C ₂ O ₄ ) ₂ ) , LiCF ₃ SO ₃ , LiFSI (LiN(SO ₂ F) ₂ ), LiCH ₃ SO ₃ , LiCF ₃ CO ₂ , LiCH ₃ CO ₂ and LiBETI (LiN(SO ₂ CF ₂ CF ₃ ) ₂ ). It may include at least one type. Specifically, the lithium salt is LiBF ₄ , LiClO ₄ , LiPF ₆ , LiBOB (LiB(C ₂ O ₄ ) ₂ ), LiCF ₃ SO ₃ , LiTFSI (LiN(SO ₂ CF ₃ ) ₂ ), LiFSI ((LiN(SO ₂ F) ₂ ) and LiBETI (LiN(SO ₂ CF ₂ CF ₃ ) ₂ ).

The lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5M to 5M, specifically 0.8M to 4M, and more specifically 0.8M to 2.0M. When the concentration of the lithium salt satisfies the above range, the lithium ion yield (Li ⁺ transference number) and the degree of dissociation of lithium ions are improved, thereby improving the output characteristics of the battery.

(2) Organic solvent

The organic solvent is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as it can minimize decomposition due to oxidation reactions, etc. during the charging and discharging process of the secondary battery.

Specifically, the organic solvent may include at least one selected from the group consisting of cyclic carbonate-based solvents, linear carbonate-based solvents, linear ester-based solvents, and cyclic ester-based solvents.

Specifically, the organic solvent may include a cyclic carbonate-based solvent, a linear carbonate-based solvent, or a mixture thereof.

The cyclic carbonate-based solvent is a high-viscosity organic solvent that has a high dielectric constant and can easily dissociate the lithium salt in the electrolyte. Specifically, it is ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, It may contain at least one organic solvent selected from the group consisting of 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and more specifically, ethylene carbonate. may include.

In addition, the linear carbonate-based solvent is an organic solvent having low viscosity and low dielectric constant, specifically dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, and ethylmethyl carbonate (EMC). , may include at least one member selected from the group consisting of methylpropyl carbonate and ethylpropyl carbonate, and more specifically may include ethylmethyl carbonate (EMC).

The organic solvent may be a mixture of a cyclic carbonate-based solvent and a linear carbonate-based solvent. At this time, the cyclic carbonate-based solvent and the linear carbonate-based solvent are mixed in a volume ratio of 10:90 to 40:60, specifically 10:90 to 30:70, and more specifically 15:85 to 30:70. You can. When the mixing ratio of the cyclic carbonate-based solvent and the linear carbonate-based solvent satisfies the above range, high dielectric constant and low viscosity characteristics can be simultaneously satisfied, and excellent ionic conductivity characteristics can be realized.

In addition, in order to prepare an electrolyte having high ionic conductivity, the organic solvent is added to at least one carbonate-based solvent selected from the group consisting of the cyclic carbonate-based solvent and the linear carbonate-based solvent as a linear ester-based solvent and a cyclic ester-based solvent. It may further include at least one ester-based solvent selected from the group consisting of

The linear ester-based solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. .

In addition, the cyclic ester solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. there is.

Meanwhile, the organic solvent can be used by adding organic solvents commonly used in non-aqueous electrolytes without limitation, if necessary. For example, it may further include at least one organic solvent selected from ether-based solvents, glyme-based solvents, and nitrile-based solvents.

The ether-based solvents include dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis (trifluoromethyl )-1,3-dioxolane (TFDOL) or a mixture of two or more of these may be used, but are not limited thereto.

The glyme-based solvent has a high dielectric constant and low surface tension compared to the linear carbonate-based solvent, and is a solvent with low reactivity with metal, such as dimethoxyethane (glyme, DME), diethoxyethane, digylme, and trimethylamine. -It may include at least one selected from the group consisting of triglyme and tetra-glyme (TEGDME), but is not limited thereto.

The nitrile-based solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, and 4-fluorobenzonitrile. , difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

(3) Additives

The non-aqueous electrolyte according to the invention contains additives.

The additive includes at least one selected from the group consisting of compounds represented by the following formulas 1 to 4.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 1 to 4, R ₁ to R ₄ are independently selected from an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms with one or more fluorine substituted, an aryl group with 6 to 30 carbon atoms, and an alkyl group with one or more fluorine substituted. It is selected from aryl groups having 6 to 30 carbon atoms, and L ₁ to L ₄ are independently selected from a direct bond, -COO-, and -SO ₂ -.

The compounds represented by Formulas 1 to 4 are cyclic phosphorene compounds in which the above-mentioned substituents are substituted with phosphorus (P), and when included in a lithium secondary battery, they can form an SEI film with excellent high-temperature durability on the positive and negative electrodes. , In particular, heat generation due to an increase in ambient temperature or battery temperature can be controlled, and the hot box safety of the battery can be significantly improved.

If hydrogen (H) is bonded to phosphorus (P) in a cyclic phosphorene compound, there is a problem that side reactions in the electrolyte become more severe as acidity increases due to deprotonation. In the present invention, electrolyte side reactions can be prevented as the above-mentioned substituent is bonded to phosphorus (P). Additionally, if oxygen (O) is directly bonded to phosphorus (P) in the cyclic phosphorene compound, unwanted side reactions may intensify before the SEI film formation reaction. For example, when the alkoxy group is directly bonded to phosphorus (P) in a cyclic phosphorene compound, the alkyl group in the alkoxy group may be replaced with Li, and in this case, the alkyl group causes a side reaction in the electrolyte, leading to the formation of a stable SEI film. It can be difficult.

In Formulas 1 to 4, R ₁ to R ₄ are independently selected from an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms with one or more fluorine substituted, an aryl group with 6 to 30 carbon atoms, and an alkyl group with one or more fluorine substituted. It may be selected from aryl groups having 6 to 30 carbon atoms, and more specifically, may be selected from alkyl groups having 1 to 10 carbon atoms and alkyl groups having 1 to 10 carbon atoms substituted with one or more fluorines, and more specifically, independently of each other, alkyl groups having 1 to 10 carbon atoms. It may be selected from an alkyl group with 1 to 5 carbon atoms and an alkyl group with 1 to 5 carbon atoms substituted with at least one fluorine, and more specifically, independently of each other, from a methyl group and a trifluoromethyl group.

In Formulas 1 to 4, L ₁ to L ₄ may be independently selected from a direct bond, -COO-, and -SO ₂ -. At this time, in the case of -COO-, carbon may be combined with phosphorus or oxygen may be combined with phosphorus, and more specifically, the carbon of -COO- may be combined with phosphorus.

More specifically, the compound represented by Formula 1 has the following Formula 1-A, Formula 1-B, Formula 1-C, Formula 1-D, Formula 1-E, Formula 1-F, Formula 2-A, and Formula 2. -B, Formula 2-C, Formula 2-D, Formula 2-E, Formula 2-F, Formula 3-A, Formula 3-B, Formula 3-C, Formula 3-D, Formula 3-E, Formula 3 -F, Formula 4-A, Formula 4-B, Formula 4-C, Formula 4-D, Formula 4-E, and Formula 4-F.

[Formula 1-A]

[Formula 1-B]

[Formula 1-C]

[Formula 1-D]

[Formula 1-E]

[Formula 1-F]

[Formula 2-A]

[Formula 2-B]

[Formula 2-C]

[Formula 2-D]

[Formula 2-E]

[Formula 2-F]

[Formula 3-A]

[Formula 3-B]

[Formula 3-C]

[Formula 3-D]

[Formula 3-E]

[Formula 3-F]

[Formula 4-A]

[Formula 4-B]

[Formula 4-C]

[Formula 4-D]

[Formula 4-E]

[Formula 4-F]

The compound represented by Formula 1 is added to the non-aqueous electrolyte in an amount of 0.005% to 12% by weight, specifically 0.01% to 10% by weight, more specifically 0.1% to 8% by weight, and even more specifically 3% to 7% by weight. It may be included in weight percent. When the content of the compound represented by Formula 1 satisfies the above range, the effect of improving the high temperature durability and safety of the battery described above is sufficiently exerted, and the resistance of the lithium secondary battery is increased by adding an excessive amount of the additive, thereby increasing the lifespan. This is desirable in terms of preventing performance degradation.

The additive may further include additional additives along with the compound of Formula 1. The additional additive may be included in the non-aqueous electrolyte to prevent decomposition of the non-aqueous electrolyte in a high-power environment, causing cathode collapse, or to improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and battery expansion inhibition at high temperatures.

Specifically, the additional additives include vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, and succino. Nitrile (succinonitrile), Adiponitrile (Adiponitrile), ethylene sulfate (ethylene sulfate), LiBF ₄ , LiPO ₂ F ₂ , LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl- propyl-N-aniline), and TMSPi (Tris(trimethylsilyl) Phosphite). Specifically, vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, ethylene sulfate, LiPO ₂ It may be at least one selected from the group consisting of F ₂ , LiBF ₄ , and LiODFB.

The additional additive may be included in the non-aqueous electrolyte in an amount of 0.1% to 15% by weight.

Lithium secondary battery

Additionally, the present invention provides a lithium secondary battery containing the above-described non-aqueous electrolyte.

Specifically, the lithium secondary battery includes a positive electrode containing a positive electrode active material; A negative electrode containing a negative electrode active material; a separator interposed between the anode and the cathode; and the non-aqueous electrolyte described above.

At this time, the lithium secondary battery of the present invention can be manufactured according to a common method known in the art. For example, the anode, the cathode, and the separator between the anode and the cathode are sequentially stacked to form an electrode assembly, and then the electrode assembly can be manufactured by inserting the inside of the battery case and injecting the non-aqueous electrolyte according to the present invention. .

(1) Anode

The positive electrode includes a positive electrode active material.

The positive electrode includes a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. At this time, the positive electrode active material may be included in the positive electrode active material layer.

The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the positive electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy, preferably aluminum.

The thickness of the positive electrode current collector may typically range from 3 to 500 ㎛.

The positive electrode current collector may form fine irregularities on the surface to strengthen the bonding force of the negative electrode active material. For example, the positive electrode current collector may be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

The positive electrode active material layer is disposed on at least one side of the positive electrode current collector. Specifically, the positive electrode active material layer may be disposed on one or both sides of the positive electrode current collector.

The positive electrode active material layer may include a positive electrode active material.

The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, a lithium transition metal complex oxide containing lithium and at least one transition metal consisting of nickel, cobalt, manganese, and aluminum, Preferably, it may include a transition metal containing nickel, cobalt, and manganese, and a lithium transition metal complex oxide containing lithium.

For example, the lithium transition metal complex oxides include lithium-manganese oxides (e.g., LiMnO ₂ , LiMn ₂ O ₄ , etc.), lithium-cobalt oxides (e.g., LiCoO ₂ , etc.), and lithium-nickel. oxides (e.g., LiNiO ₂ , etc.), lithium-nickel-manganese oxides (e.g., 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-based oxides (e.g., LiCo _1-Y2 Mn _Y2 O ₂ (where 0<Y2<1), LiMn _2-z1 Co _z1 O ₄ (where 0<Z1<2), etc.), lithium -Nickel-manganese-cobalt oxide (for example, Li(Ni _p Co _q Mn _r1 )O ₂ (where 0<p<1, 0<q<1, 0<r1<1, p+q+ r1=1) or Li(Ni _p1 Co _q1 Mn _r2 )O ₄ (where 0<p1<2, 0<q1<2, 0<r2<2, p1+q1+r2=2), etc.), or Lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni _p2 Co _q2 Mn _r3 M _S2 )O ₂ (where M is Al, Fe, V, Cr, Ti, Ta, Mg and It is selected from the group consisting of Mo, and p2, q2, r3 and s2 are each independent atomic fraction of elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, p2 +q2+r3+s2=1), etc.), and any one or two or more of these compounds may be included. Among these, in that the capacity characteristics and stability of the battery can be improved, the lithium transition metal composite oxide is LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , lithium nickel-manganese-cobalt oxide (for example, Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li(Ni _0.5 Mn _0.3 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 etc.), or lithium nickel cobalt aluminum oxide (e.g. For example, it may be Li (Ni _0.8 Co _0.15 Al _0.05 )O ₂ , etc.), and considering the remarkable improvement effect due to control of the type and content ratio of the constituent elements forming the lithium transition metal complex oxide, the lithium transition metal The complex oxide is Li(Ni _0.6 Mn _0.2 Co _0.2 )O ₂ , Li(Ni _0.5 Mn _0.3 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 etc., and any one or a mixture of two or more of these may be used.

More specifically, the positive electrode active material is a lithium transition metal complex oxide and may contain 60 mol% or more of nickel based on the total number of moles of transition metals contained in the lithium transition metal complex oxide. Specifically, the positive electrode active material is a lithium transition metal complex oxide, and the transition metal includes nickel; and at least one selected from manganese, cobalt, and aluminum, and may include nickel in an amount of 60 mol% or more, specifically 60 mol% to 90 mol%, based on the total number of moles of the transition metal. When this lithium transition metal complex oxide using a high content of nickel is used together with the above-described non-aqueous electrolyte, it is preferable in that it can reduce by-products in the gas phase generated by structural collapse.

The positive electrode active material may be included in the positive electrode active material layer at 80% to 99% by weight, preferably 92% to 98.5% by weight, in consideration of sufficient capacity of the positive electrode active material.

The positive electrode active material layer may further include a binder and/or a conductive material along with the positive electrode active material described above.

The binder is a component that helps bind active materials and conductive materials and bind to the current collector, and is specifically made of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, and hydroxypropyl cellulose. From the group consisting of wood, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber and fluoroelastomer. It may include at least one selected type, preferably polyvinylidene fluoride.

The binder may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in terms of ensuring sufficient binding force between components such as the positive electrode active material.

The conductive material can be used to assist and improve conductivity in secondary batteries, and is not particularly limited as long as it has conductivity without causing chemical changes. Specifically, the anode conductive material includes graphite such as natural graphite or artificial graphite; Carbon black, such as carbon black, acetylene black, Ketjen black, channel black, Paneth black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Conductive tubes such as carbon nanotubes; fluorocarbon; Metal powders such as aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and may preferably include carbon black in terms of improving conductivity.

In terms of ensuring sufficient electrical conductivity, the conductive material may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight.

The thickness of the positive electrode active material layer may be 30㎛ to 400㎛, preferably 40㎛ to 110㎛.

The positive electrode may be manufactured by coating a positive electrode slurry containing a positive electrode active material and optionally a binder, a conductive material, and a solvent for forming a positive electrode slurry on the positive electrode current collector, followed by drying and rolling.

The solvent for forming the positive electrode slurry may include an organic solvent such as NMP (N-methyl-2-pyrrolidone). The solid content of the positive electrode slurry may be 40% by weight to 90% by weight, specifically 50% by weight to 80% by weight.

(2) cathode

The cathode may face the anode.

The negative electrode includes a negative electrode active material.

The negative electrode includes a negative electrode current collector; and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. At this time, the negative electrode active material may be included in the negative electrode active material layer.

The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the negative electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. there is.

The negative electrode current collector may typically have a thickness of 3 to 500 ㎛.

The negative electrode current collector may form fine irregularities on the surface to strengthen the bonding force of the negative electrode active material. For example, the negative electrode current collector may be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics.

The negative electrode active material layer is disposed on at least one side of the negative electrode current collector. Specifically, the negative electrode active material layer may be disposed on one or both sides of the negative electrode current collector.

The negative electrode active material layer may include a negative electrode active material.

The negative electrode active material is a material capable of reversibly inserting/extracting lithium ions, and may include at least one selected from the group consisting of carbon-based active materials, (semi-)metal-based active materials, and lithium metal, and specifically, carbon-based active materials. and (semi-)metal-based active materials.

The carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably consists of artificial graphite and natural graphite. It may include at least one species selected from the group.

The average particle diameter (D ₅₀ ) of the carbon-based active material may be 10 ㎛ to 30 ㎛, preferably 15 ㎛ to 25 ㎛, in terms of ensuring structural stability during charging and discharging and reducing side reactions with the electrolyte solution.

Specifically, the (semi-)metal-based active materials include Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, At least one (semi-)metal selected from the group consisting of V, Ti, and Sn; From the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn. An alloy of lithium and at least one selected (semi-)metal; From the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn. An oxide of at least one selected (semi-)metal; Lithium Titanium Oxide (LTO); lithium vanadium oxide; It may include etc.

More specifically, the (semi-)metal-based active material may include a silicon-based active material.

The silicon-based active material may include a compound represented by SiO _x (0≤x<2). In the case of SiO ₂ , since lithium cannot be stored because it does not react with lithium ions, x is preferably within the above range, and more preferably, the silicon-based oxide may be SiO.

The average particle diameter (D ₅₀ ) of the silicon-based active material may be 1 ㎛ to 30 ㎛, preferably 2 ㎛ to 15 ㎛ in terms of reducing side reactions with the electrolyte solution while ensuring structural stability during charging and discharging.

The negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight, preferably 75% to 95% by weight.

The negative electrode active material layer may further include a binder and/or a conductive material along with the negative electrode active material.

The binder is used to improve battery performance by improving adhesion between the negative electrode active material layer and the negative electrode current collector, for example, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co- HFP), polyvinylidenefluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, recycled Cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoroelastomer, and hydrogen thereof. It may include at least one selected from the group consisting of substances substituted with Li, Na, or Ca, and may also include various copolymers thereof.

The binder may be included in the negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

The conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, graphite such as natural graphite or artificial graphite; Carbon black, such as carbon black, acetylene black, Ketjen black, channel black, Paneth black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Conductive tubes such as carbon nanotubes; fluorocarbon; Metal powders such as 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 may be included in the negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

The thickness of the negative electrode active material layer may be 10㎛ to 100㎛, preferably 50㎛ to 80㎛.

The negative electrode may be manufactured by coating at least one surface of a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and/or a solvent for forming a negative electrode slurry, followed by drying and rolling.

The solvent for forming the negative electrode slurry is, for example, distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol in terms of facilitating dispersion of the negative electrode active material, binder, and/or conductive material. It may contain at least one selected from the group, preferably distilled water. The solid content of the negative electrode slurry may be 30% by weight to 80% by weight, specifically 40% by weight to 70% by weight.

(3) Separator

In addition, the separator includes typical porous polymer films conventionally used as separators, such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer. Porous polymer films made of the same polyolefin polymer can be used alone or by laminating them, or conventional porous nonwoven fabrics, such as high melting point glass fibers, polyethylene terephthalate fibers, etc., can be used. It is not limited. Additionally, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

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

Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are only examples to aid understanding of the present invention and do not limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical spirit of the present description, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

Examples and Comparative Examples

Example 1

(Preparation of non-aqueous electrolyte)

As an organic solvent, a mixture of ethylene carbonate (EC) and ethylmethyl carbonate (EMC) in a volume ratio of 2:8 was used.

LiPF ₆ as a lithium salt in the organic solvent; And a compound represented by Formula 1-A was added to prepare a non-aqueous electrolyte.

The LiPF ₆ was included in the non-aqueous electrolyte at a molar concentration of 1.2M.

The compound represented by Formula 1-A was included at 5% by weight in the non-aqueous electrolyte.

(Lithium secondary battery manufacturing)

Cathode active material (Li[Ni _0.6 Co _0.2 Mn _0.2 ]O ₂ ): conductive material (carbon black): binder (polyvinylidene fluoride) in a weight ratio of 98:1:1 and N-methyl-2-pyrrolidone as a solvent. (NMP) was added to prepare a positive electrode mixture slurry (solid content: 60% by weight). The positive electrode mixture slurry was applied to one side of a positive electrode current collector (Al thin film) with a thickness of 15㎛, and dried and roll pressed to prepare a positive electrode.

Anode active material (natural graphite): conductive material (carbon black): binder (SBR-CMC) was added to distilled water as a solvent in a weight ratio of 95:3.5:1.5 to prepare a negative electrode mixture slurry (solid content: 60% by weight). The negative electrode mixture slurry was applied to one side of a negative electrode current collector (Cu thin film) with a thickness of 10㎛, and dried and roll pressed to prepare a negative electrode.

A polyethylene porous film separator was interposed between the prepared positive electrode and the negative electrode in a dry room, and then the prepared non-aqueous electrolyte was injected to prepare a secondary battery.

Example 2

A non-aqueous electrolyte and a secondary battery were prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-A to the non-aqueous electrolyte in an amount of 0.01% by weight.

Example 3

A non-aqueous electrolyte and a secondary battery were prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-A to the non-aqueous electrolyte in an amount of 10% by weight.

Example 4

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-B to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. and a secondary battery was manufactured.

Example 5

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-C to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. and a secondary battery was manufactured.

Example 6

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-D to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. and a secondary battery was manufactured.

Example 7

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-E to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. And a secondary battery was manufactured.

Example 8

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 1-F to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. And a secondary battery was manufactured.

Example 9

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 2-A to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. And a secondary battery was manufactured.

Example 10

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 3-A to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. and a secondary battery was manufactured.

Example 11

A non-aqueous electrolyte was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula 4-A to the non-aqueous electrolyte in an amount of 5% by weight instead of the compound represented by Formula 1-A. And a secondary battery was manufactured.

Comparative Example 1

A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by Formula 1-A was not added to the non-aqueous electrolyte.

Comparative Example 2

Non-aqueous electrolyte and secondary electrolyte were prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula A battery was manufactured.

[Formula X]

Comparative Example 3

Non-aqueous electrolyte and secondary electrolyte were prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula Y instead of the compound represented by Formula 1-A to the non-aqueous electrolyte in an amount of 5% by weight. A battery was manufactured.

[Formula Y]

Comparative Example 4

Non-aqueous electrolyte and secondary electrolyte were prepared in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared by adding the compound represented by Formula Z instead of the compound represented by Formula 1-A to the non-aqueous electrolyte in an amount of 5% by weight. A battery was manufactured.

[Formula Z]

Experiment example

Experimental Example 1: Evaluation of high temperature cycle characteristics

High-temperature cycle characteristics were evaluated for each of the secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 6.

Specifically, each of the secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 6 were charged under constant current/constant voltage conditions up to 4.2V at 0.33C at 45°C (0.05C cut-off), and 3.0 at 0.33C. Discharging under constant current conditions to V was considered one cycle, and 200 cycles of charge and discharge were performed, and the capacity retention rate and resistance increase rate were evaluated.

The capacity retention rate was calculated by the following equation.

Capacity retention rate (%) = {(discharge capacity after 200 cycles/discharge capacity after 1 cycle)} × 100

Additionally, the resistance increase rate was measured and calculated as follows.

After 1 cycle of charging and discharging, measure the discharge capacity after 1 cycle using an electrochemical charging and discharging device, adjust the SOC to 50%, and then apply a pulse of 2.5C for 10 seconds to reduce the voltage before applying the pulse. The initial resistance was calculated through the difference in voltage after application.

After 200 cycles of charging and discharging, the resistance after 200 cycles of charging and discharging was calculated in the same manner as above.

The resistance increase rate was calculated by the following equation.

Resistance increase rate (%) = {(Resistance after 200 cycles of charge/discharge - initial resistance)/(initial resistance)} × 100

The results are shown in Table 1 below.

Experimental Example 2: Evaluation of capacity retention rate during high temperature storage

High-temperature storage characteristics were evaluated for each of the secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 6.

Specifically, each of the secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 6 were fully charged to 4.2V and then stored at 60°C for 8 weeks.

Before storage, the capacity of the fully charged secondary battery was measured and set as the initial capacity.

After 8 weeks, the capacity of the preserved secondary battery was measured and the capacity decreased during the 8-week storage period was calculated. The percentage ratio of the reduced dose to the initial dose was calculated to derive the dose maintenance rate after 8 weeks. The results are shown in Table 1 below.

Experimental Example 3: Evaluation of resistance increase rate when stored at high temperature

The lithium secondary batteries of Examples 1 to 11 and Comparative Examples 1 to 4 prepared above were charged to 4.2V under CC/CV, 0.33C conditions at 25°C and discharged to 2.5V at 0.33C to perform initial charge and discharge. , After checking the capacity at room temperature, charge to SOC 50% based on the discharge capacity, discharge for 10 seconds at 2.5C current, measure the resistance using the voltage drop difference at this time to determine the initial resistance, and store it at 60℃ for 8 weeks, then use the same method. The resistance was measured and this was used as the final resistance to calculate the resistance increase rate using the following equation. The results are shown in Table 1 below.

Resistance increase rate (%) = (final resistance - initial resistance) / (initial resistance) × 100

Experimental Example 4: Thermal stability evaluation

Thermal stability was evaluated for each of the secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 4.

Specifically, a formation process was performed on the lithium secondary batteries manufactured in the above examples and comparative examples, and then charging was performed under constant current/constant current conditions up to 4.2V at 0.33C at 25°C (0.05C cut-off). Thus, the SOC was fully charged to 100%. A hot box evaluation experiment was conducted in which fully charged batteries were heated to 140°C at a temperature increase rate of 5°C/min, then left for 1 hour to check for ignition. Cases where ignition did not occur were evaluated as Pass, cases where ignition occurred were evaluated as Fail, and the results are shown in Table 1 below.

Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Capacity maintenance rate (%)
(45℃, 200cycle) Resistance increase rate (%)
(45℃, 200cycle) Capacity maintenance rate (%)
(60℃, stored for 8 weeks) Resistance increase rate (%)
(60℃, storage for 8 weeks) Thermal stability evaluation (Pass/Fail) Example 1 91 7 95 7 Pass Example 2 90 6 95 7 Pass Example 3 92 8 96 8 Pass Example 4 90 6 95 7 Pass Example 5 91 8 96 7 Pass Example 6 90 7 94 6 Pass Example 7 91 7 95 8 Pass Example 8 90 6 94 7 Pass Example 9 90 6 95 7 Pass Example 10 90 5 96 9 Pass Example 11 91 7 94 6 Pass Comparative Example 1 84 19 85 18 Fail Comparative Example 2 82 23 86 24 Fail Comparative Example 3 81 17 86 20 Fail Comparative Example 4 84 22 85 17 Pass

Referring to Table 1, the lithium secondary batteries of Examples 1 to 11 containing the non-aqueous electrolyte according to the present invention have life characteristics and resistance characteristics during high-temperature cycle charging and discharging and high-temperature storage compared to Comparative Examples 1 to 4. It can be seen that, in addition to being excellent, thermal stability is significantly improved.

Claims (10)

lithium salt;
organic solvent; and
Contains additives;
The additive is a non-aqueous electrolyte containing at least one selected from the group consisting of compounds represented by the following formulas 1 to 4:
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 1 to 4, R ₁ to R ₄ are independently selected from an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms with one or more fluorine substituted, an aryl group with 6 to 30 carbon atoms, and an alkyl group with one or more fluorine substituted. selected from aryl groups having 6 to 30 carbon atoms,
L ₁ to L ₄ are independently selected from a direct bond, -COO-, and -SO ₂ -.
In claim 1,
In Formulas 1 to 4, R ₁ to R ₄ are independently selected from an alkyl group having 1 to 10 carbon atoms and an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorine.
In claim 1,
In Formulas 1 to 4, R ₁ to R ₄ are each independently selected from a methyl group and a trifluoromethyl group.
In claim 1,
The compound represented by Formula 1 has the following Formula 1-A, Formula 1-B, Formula 1-C, Formula 1-D, Formula 1-E, Formula 1-F, Formula 2-A, Formula 2-B, Formula 2-C, Formula 2-D, Formula 2-E, Formula 2-F, Formula 3-A, Formula 3-B, Formula 3-C, Formula 3-D, Formula 3-E, Formula 3-F, Formula A non-aqueous electrolyte comprising at least one member selected from the group consisting of 4-A, Formula 4-B, Formula 4-C, Formula 4-D, Formula 4-E, and Formula 4-F:
[Formula 1-A]

[Formula 1-B]

[Formula 1-C]

[Formula 1-D]

[Formula 1-E]

[Formula 1-F]

[Formula 2-A]

[Formula 2-B]

[Formula 2-C]

[Formula 2-D]

[Formula 2-E]

[Formula 2-F]

[Formula 3-A]

[Formula 3-B]

[Formula 3-C]

[Formula 3-D]

[Formula 3-E]

[Formula 3-F]

[Formula 4-A]

[Formula 4-B]

[Formula 4-C]

[Formula 4-D]

[Formula 4-E]

[Formula 4-F]

In claim 1,
The compound represented by Formula 1 is a non-aqueous electrolyte contained in an amount of 0.005% to 12% by weight in the non-aqueous electrolyte.
In claim 1,
The lithium salt is LiCl, LiBr, LiI, LiBF ₄ , LiClO ₄ , LiAlO ₄ , LiAlCl ₄ , LiPF ₆ , LiSbF ₆ , LiAsF ₆ , LiB ₁₀ Cl ₁₀ , LiBOB (LiB(C ₂ O ₄ ) ₂ ), LiCF ₃ At least one selected from the group consisting of SO ₃ , LiFSI (LiN(SO ₂ F) ₂ ), LiCH ₃ SO ₃ , LiCF ₃ CO ₂ , LiCH ₃ CO ₂ and LiBETI (LiN(SO ₂ CF ₂ CF ₃ ) ₂ ) A non-aqueous electrolyte containing.
In claim 1,
The lithium salt is included in the non-aqueous electrolyte at a molar concentration of 0.5 M to 5.0 M.
In claim 1,
The organic solvent is a non-aqueous electrolyte comprising at least one selected from the group consisting of a cyclic carbonate-based solvent, a linear carbonate-based solvent, a linear ester-based solvent, and a cyclic ester-based solvent.
In claim 1,
The additives include vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, LiPO ₂ F ₂ , LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis- (oxalato)borate), 3-trimethoxysilanyl-propyl-N-aniline (TMSPa), and Tris(trimethylsilyl) Phosphite (TMSPi).
A positive electrode containing a positive electrode active material;
A negative electrode containing a negative electrode active material;
a separator interposed between the anode and the cathode; and
A lithium secondary battery comprising the non-aqueous electrolyte according to claim 1.