WO2017057968A1 - Non-aqueous electrolyte and lithium secondary battery comprising same - Google Patents

Abstract

The present invention relates to: a non-aqueous electrolyte comprising a non-aqueous organic solvent, lithium bis(fluorosulfonyl)imide (LiFSI), and a pyridine-based compound represented by chemical formula 1; and a lithium secondary battery comprising same. The lithium secondary battery according to the present invention, comprising the non-aqueous electrolyte according to the present invention, can exhibit excellent low-temperature and room temperature output characteristics, high-temperature and room temperature cycle characteristics, and capacity characteristics after storage at a high temperature.

Description

Non-aqueous electrolyte solution and lithium secondary battery comprising the same

[Cross-cited with Related Applications]

This application claims the benefit of priority based on Korean Patent Application Nos. 10-2015-0138039 and 10-2015-0138040, filed September 30, 2015, and Korean Patent Application No. 10-2016-0125915, filed September 29, 2016. All contents disclosed in the literature of the Korean patent application are included as part of the present specification.

[Technical Field]

The present invention is a non-aqueous organic solvent, lithium bis (fluorosulfonyl) imide (LiFSI) and a non-aqueous electrolyte containing a pyridine-based compound represented by Formula 1, and a lithium secondary battery comprising the same It is about.

As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing, and lithium secondary batteries having high energy density and voltage are commercially used.

Lithium metal oxide is used as a positive electrode active material of a lithium secondary battery, and lithium metal, a lithium alloy, crystalline or amorphous carbon or a carbon composite material is used as a negative electrode active material. The active material is applied to a current collector with a suitable thickness and length, or the active material itself is coated in a film shape to be wound or laminated with a separator, which is an insulator, to form an electrode group, and then placed in a can or a similar container, and then injected with an electrolyte solution. A secondary battery is manufactured.

In such a lithium secondary battery, charging and discharging progress while repeating a process of intercalating and deintercalating lithium ions from a lithium metal oxide of a positive electrode to a graphite electrode of a negative electrode. At this time, lithium is highly reactive and reacts with the carbon electrode to generate Li ₂ CO ₃ , LiO, LiOH and the like to form a film on the surface of the negative electrode. Such a film is called a solid electrolyte interface (SEI) film, and the SEI film formed at the beginning of charging prevents a reaction between lithium ions and a carbon anode or other material during charge and discharge. It also acts as an ion tunnel, allowing only lithium ions to pass through. The ion tunnel serves to prevent organic solvents of a large molecular weight electrolyte that solvate lithium ions and move together to co-intercalate the carbon anode to decay the structure of the carbon anode. do.

Therefore, in order to improve the high temperature cycle characteristics and the low temperature output of the lithium secondary battery, a solid SEI film must be formed on the negative electrode of the lithium secondary battery. Once formed, the SEI membrane prevents the reaction between lithium ions and the negative electrode or other materials during repeated charge / discharge cycles, and serves as an ion tunnel that passes only lithium ions between the electrolyte and the negative electrode. Will be performed.

On the other hand, various non-aqueous organic solvents have been used in the electrolyte solution. For example, propylene carbonate is mainly used as a non-aqueous organic solvent, but this has a problem of causing an irreversible decomposition reaction with graphite materials. In order to replace this, two- and three-component non-aqueous organic solvents including ethylene carbonate (EC) as a base have been used. However, ethylene carbonate has a high melting point, which limits the use temperature, and has a problem that can lead to a significant decrease in battery performance at low temperatures.

The problem to be solved of the present invention is not only to improve the low temperature and room temperature output characteristics, but also to a non-aqueous electrolyte solution that can improve the room temperature and high temperature cycle characteristics, and the capacity characteristics after high temperature storage, and a lithium secondary battery comprising the same To provide.

In order to solve the above problems, the present invention comprises a non-aqueous organic solvent, lithium bis (fluorosulfonyl) imide (LiFSI) and a pyridine-based compound represented by the formula (1), It provides a nonaqueous electrolyte solution.

[Formula 1]

In addition, the present invention is a positive electrode comprising a positive electrode active material; A negative electrode including a negative electrode active material; A separator interposed between the positive electrode and the negative electrode; And the non-aqueous electrolyte solution, wherein the cathode active material includes a manganese spinel-based active material, a lithium metal oxide, or a mixture thereof.

The non-aqueous electrolyte of the present invention forms a solid SEI film at the negative electrode during initial charging of the lithium secondary battery including the same, thereby improving the low temperature and room temperature output characteristics, as well as the high temperature and room temperature cycle characteristics, and the capacity after high temperature storage. Can improve.

Hereinafter, the present invention will be described in more detail to aid in understanding the present invention. The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

The non-aqueous electrolyte of the present invention includes a non-aqueous organic solvent, lithium bis (fluorosulfonyl) imide (LiFSI), and a pyridine-based compound represented by Chemical Formula 1.

[Formula 1]

Since the non-aqueous electrolyte includes lithium bisfluorosulfonylimide in the non-aqueous organic solvent, by forming a solid SEI film at the cathode during initial charging, the low temperature and room temperature output characteristics are improved, as well as during high temperature cycle operation of 45 ° C. or more. It is possible to simultaneously improve the capacity characteristics of the lithium secondary battery by inhibiting decomposition of the surface of the positive electrode and preventing oxidation of the electrolyte.

In addition, since the non-aqueous electrolyte solution includes a pyridine-based compound represented by Chemical Formula 1, the pyridine-based compound represented by Chemical Formula 1 decomposes upon activation to participate in the formation of the SEI film of the negative electrode, thereby forming a rigid film, and the density of the SEI film. It can be made thin while increasing the, it is possible to improve the life characteristics of the battery and durability at high temperature storage.

The content of the pyridine-based compound represented by Formula 1 may be 0.01% to 3% by weight, specifically 0.05% to 2% by weight, and more specifically 0.6% by weight, based on the total weight of the nonaqueous electrolyte. To 1.5% by weight.

When the content of the pyridine-based compound represented by the formula (1) is 0.01% by weight or more, an appropriate effect may be expected due to the addition of the pyridine-based compound, when the content of the pyridine-based compound is 3% by weight or less, it exhibits an appropriate degree However, it is possible to prevent problems such as increasing the irreversible capacity of the battery or increasing electrode resistance due to the formation of thick SEI.

As the non-aqueous organic solvent, decomposition may be minimized by an oxidation reaction or the like during the charging and discharging process of the battery, and may be used without limitation as long as the non-aqueous organic solvent may exhibit desired properties with an additive, such as a nitrile solvent, a cyclic carbonate, Linear carbonates, esters, ethers or ketones. These may be used alone, or two or more thereof may be used in combination.

Among the organic solvents, a carbonate-based organic solvent may be easily used. The cyclic carbonate may be any one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Mixtures of two or more kinds include linear carbonates, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate. (EPC) can be mentioned any one selected from the group consisting of or a mixture of two or more thereof.

The nitrile solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile and 4-fluorobenzonitrile It may be one or more selected from the group consisting of, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile.

The ester may be ethyl propionate (EP), methyl propionate (MP), and mixtures thereof.

The non-aqueous electrolyte according to an example of the present invention may include propylene carbonate (PC) and ethylene carbonate (EC) as the non-aqueous organic solvent.

The ethylene carbonate (EC) has been mainly used as a non-aqueous organic solvent used for non-aqueous electrolyte in lithium secondary batteries due to its excellent affinity with carbon materials. However, when EC is used too much, CO ₂ gas is generated due to EC decomposition, which may adversely affect the performance of the secondary battery, and low temperature characteristics are poor due to high melting point characteristics and low conductivity. As a result, there is a problem that the high output characteristics are low.

On the contrary, the non-aqueous electrolyte containing propylene carbonate has a characteristic of having high output characteristics due to excellent low temperature characteristics and high conductivity. However, propylene carbonate has a problem in that its use with graphite is limited because it causes an irreversible decomposition reaction with the graphite material. In addition, there is a problem that a capacity decrease of the lithium secondary battery occurs due to electrode exfoliation due to propylene carbonate during high temperature cycles depending on the electrode thickness.

In particular, when propylene carbonate is used together with a lithium salt such as LiPF ₆ as a non-aqueous organic solvent, propylene carbonate is a process of forming an SEI film in a lithium secondary battery using a carbon electrode, and lithium ions solvated by propylene carbonate. Enormous capacity of irreversible reactions can occur in the intercalation between these carbon layers. This may cause a problem that the performance of the battery, such as cycle characteristics is degraded.

In addition, when lithium ions solvated by propylene carbonate are inserted into the carbon layer constituting the negative electrode, exfoliation of the carbon surface layer may proceed. This delamination can be caused by the gas generated when the solvent decomposes between the carbon layers causing a large distortion between the carbon layers. Such peeling of the surface layer and decomposition of the electrolyte may proceed continuously, and thus, when the propylene carbonate electrolyte is used in combination with the carbon-based negative electrode material, an effective SEI film may not be generated and lithium ions may not be inserted.

Therefore, when the amount of the ethylene carbonate and the propylene carbonate are used in combination as a non-aqueous organic solvent so as to have an appropriate composition, the conductivity characteristics of the non-aqueous electrolyte solution may be improved to improve the output characteristics of the lithium secondary battery and to improve the low temperature characteristics. It is possible to provide a non-aqueous electrolyte having excellent electrochemical affinity with the carbon layer.

In order to overcome the problems of ethylene carbonate and propylene carbonate and make the best use of the advantages, the non-aqueous electrolyte according to an example of the present invention may include the propylene carbonate and the ethylene carbonate (EC), such as 1: 0.1 to 1: 2. It may be included in a weight ratio, in particular a weight ratio of 1: 0.3 to 1: 1, more specifically 1: 0.4 to 1: 0.9 weight ratio.

When the non-aqueous organic solvent includes the propylene carbonate (PC) and ethylene carbonate (EC) in the mixing ratio, it solves the problems that occur when using propylene carbonate (PC) and ethylene carbonate (EC), respectively, Taking advantage of the solvent, synergistic effects due to the mixing of the non-aqueous organic solvent can be expressed. According to an example of the present invention, the mixing ratio of the propylene carbonate and the ethylene carbonate (EC) solvent as the non-aqueous organic solvent may have a significant influence on improving both low temperature and room temperature output and capacity characteristics after high temperature storage.

On the other hand, the non-aqueous electrolyte solution of the present invention can be solved by combining the above problems when using a lithium salt such as propylene carbonate and LiPF ₆ together using lithium bisfluorosulfonyl imide.

Specifically, the lithium bisfluorosulfonylimide is added to the non-aqueous electrolyte as a lithium salt to form a solid and stable SEI film on the cathode, thereby improving low temperature output characteristics, and of the surface of the anode which may occur during high temperature cycle operation. Decomposition can be suppressed and oxidation reaction of electrolyte solution can be prevented.

The propylene carbonate may include 5 parts by weight to 60 parts by weight, specifically 10 parts by weight to 40 parts by weight based on 100 parts by weight of the total non-aqueous organic solvent. When the content of the propylene carbonate is less than 5 parts by weight, a swelling phenomenon may occur in which a gas is continuously generated due to decomposition of the surface of the positive electrode during a high temperature cycle, and an initial rechargeable battery negative electrode may exceed 60 parts by weight. It is difficult to form a solid SEI film at, and high temperature properties may be degraded.

When the ethylene carbonate is properly adjusted to be within the range of the mixing ratio within the amount of the propylene carbonate used, the optimum effect can be achieved not only in the low temperature and room temperature output characteristics of the lithium secondary battery of the present invention, but also in the capacity characteristics after high temperature storage. have.

The non-aqueous organic solvent may further include a non-aqueous organic solvent other than propylene carbonate (PC) and ethylene carbonate (EC), the decomposition by the oxidation reaction, etc. in the charge and discharge of the battery can be minimized, with an additive There is no limit as long as it can exhibit the desired characteristics.

As the non-aqueous organic solvent which may be further included in the non-aqueous electrolyte, for example, ethyl propionate (EP), methyl propionate (MP), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate ( DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate (EPC), any one selected from the group consisting of, or a mixture of two or more thereof. .

Meanwhile, the lithium bisfluorosulfonyl imide may have a concentration in the non-aqueous electrolyte solution of 0.01 mol / L to 2 mol / L.

Specifically, when the non-aqueous electrolyte according to an example of the present invention comprises propylene carbonate (PC) and ethylene carbonate (EC) as the non-aqueous organic solvent, the concentration of lithium bisfluorosulfonylimide in the non-aqueous electrolyte 0.1 mol / L to 2 mol / L, and more specifically 0.5 mol / L to 1.5 mol / L. When the concentration of the lithium bisfluorosulfonylimide is less than 0.1 mol / L, the effect of improving the low temperature output and the high temperature cycle characteristics of the battery may be insignificant, and the concentration of the lithium bisfluorosulfonylimide is 2 When the mol / L is exceeded, side reactions in the electrolyte may be excessively generated during charging and discharging of the battery, and a swelling phenomenon may occur, and corrosion of the positive electrode or the negative electrode current collector made of metal in the electrolyte may occur.

In order to further prevent such side reactions, the non-aqueous electrolyte of the present invention may further include lithium salts other than the lithium bisfluorosulfonylimide. The lithium salt may be used a lithium salt commonly used in the art, for example LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , CF ₃ SO ₃ Li, LiC (CF ₃ SO ₂ ) ₃ And LiC ₄ BO _{8 It} may be any one selected from the group consisting of or a mixture of two or more thereof.

The mixing ratio of the lithium salt and lithium bisfluorosulfonylimide may be 1: 0.01 to 1: 9 in a molar ratio.

Specifically, when the non-aqueous electrolyte according to an example of the present invention contains propylene carbonate (PC) and ethylene carbonate (EC) as the non-aqueous organic solvent, the mixing ratio of the lithium salt and lithium bisfluorosulfonylimide is The molar ratio may be 1: 1 to 1: 9. When the mixing ratio of the lithium salt and lithium bisfluorosulfonylimide is out of the range of the molar ratio, side reactions in the electrolyte may be excessively generated during charging and discharging of the battery, and a swelling phenomenon may occur.

More specifically, when the non-aqueous electrolyte according to an example of the present invention contains propylene carbonate (PC) and ethylene carbonate (EC) as the non-aqueous organic solvent, the mixing ratio of the lithium salt and lithium bisfluorosulfonylimide May be from 1: 6 to 1: 9 in molar ratio. For example, when the mixing ratio of the lithium salt and lithium bisfluorosulfonylimide is 1: 6 or more in molar ratio, a process of forming an SEI film in a lithium ion battery, and lithium ions solvated by propylene carbonate and ethylene carbonate It can prevent the irreversible reaction of enormous capacity in the process of being inserted between the negative electrodes, suppress the peeling of the negative electrode surface layer (for example, carbon surface layer) and decomposition of the electrolyte solution, thereby improving the low-temperature output of the secondary battery, high temperature storage After that, the effect of improving cycle characteristics and capacity characteristics can be exerted.

The content of the pyridine-based compound represented by Formula 1 may be adjusted according to the addition amount of lithium bisfluoro sulfonyl imide.

The lithium bisfluoro sulfonyl imide and the pyridine-based compound represented by Formula 1 may be used in a weight ratio of 1: 0.001 to 1: 5, specifically, may be used in a weight ratio of 1: 0.005 to 1: 3, and more Specifically, it may be used in a weight ratio of 1: 0.01 to 1: 2.5.

When the lithium bis fluoro sulfonyl imide and the pyridine-based compound represented by Chemical Formula 1 are used in a weight ratio of 1: 0.001 to 1: 5, lithium may be generated by the addition of the lithium bis fluoro sulfonyl imide. While the side reactions in the electrolyte at room temperature of the secondary battery can be appropriately suppressed by the pyridine-based compound represented by Formula 1 above, the side reactions such as metal elution of the positive electrode can be improved, and the high temperature durability can be improved by forming a solid film on the negative electrode. Can exert the effect of.

In addition, the present invention is a positive electrode comprising a positive electrode active material; A negative electrode including a negative electrode active material; A separator interposed between the positive electrode and the negative electrode; And the non-aqueous electrolyte solution, wherein the cathode active material includes a manganese spinel-based active material, a lithium metal oxide, or a mixture thereof.

The lithium metal oxide may be selected from the group consisting of lithium-manganese oxide, lithium-nickel-manganese oxide, lithium-manganese-cobalt oxide, and lithium-nickel-manganese-cobalt oxide. Specifically, the cathode active material may be LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li _{1 + x} (Ni _a Co _b Mn _c ) O ₂ (where 0.55 ≦ a ≦ 0.65, 0.18 ≦ _b ≦ 0.22, 0.18≤c≤0.22, -0.2≤x≤0.2, x + a + b + c = 1), Li (Ni _{a '} Co _b' Mn _{c '} ) O ₂ (where 0 <a'<1, 0 < b '<1, 0 <c'<1, a '+ b' + c '= 1), LiNi _{1 - Y} Co _Y O ₂ (where 0 ≦ Y <1) and LiCo _{1 - Y'} Mn _{Y '} O ₂ (where, 0≤Y '<1), LiNi 1-Y "Mn Y" O 2 ( where, 0≤Y "<1), Li (Ni d Co e Mn f) O 4 (0 <d < 2, 0 <e <2, 0 <f <2, d + e + f = 2), LiMn 2 - z Ni z O 4 ( where, 0 <z <2), LiMn 2 - z 'Co z' O ₄ , where 0 <Z '<2.

Meanwhile, in one example of the present invention, the lithium metal oxide may be a lithium-nickel-manganese-cobalt-based oxide, and specifically, the lithium-nickel-manganese-cobalt-based oxide may include an oxide represented by Formula 2 below. Can be.

[Formula 2]

Li _{1 + x} (Ni _a Co _b Mn _c ) O ₂

(In Formula 2, 0.55≤a≤0.65, 0.18≤b≤0.22, 0.18≤c≤0.22, -0.2≤x≤0.2, and x + a + b + c = 1.)

When the lithium-nickel-manganese-cobalt-based oxide is used for the positive electrode as the positive electrode active material, it may have a synergistic effect in combination with lithium bisfluoro sulfonyl imide included in the non-aqueous electrolyte. In the lithium-nickel-manganese-cobalt-based oxide positive electrode active material, Li + 1 ions and Ni + 2 ions in the layered structure of the cathode active material are changed in the charge and discharge process as the content of Ni in the transition metal increases. cation mixing occurs and the structure collapses, and the positive electrode active material causes side reactions with the electrolyte, or dissolution of transition metals. This occurs because Li +1 ions and Ni +2 ions have similar sizes. As a result, the performance of the battery is easily degraded due to electrolyte depletion and structural collapse of the positive electrode active material inside the secondary battery.

Accordingly, the lithium secondary battery according to an embodiment of the present invention uses a non-aqueous electrolyte solution containing LiFSI together with the positive electrode active material of Formula 2, and forms a layer with a component derived from LiFSI on the surface of the positive electrode to form Li +1. While suppressing cation mixing of the valent ions and the Ni +2 ions, a sufficient amount of nickel transition metal for securing the capacity of the positive electrode active material can be obtained. Since the lithium secondary battery according to an example of the present invention includes a non-aqueous electrolyte solution containing LiFSI together with the oxide represented by Chemical Formula 2, side reaction between the electrolyte solution and the positive electrode, metal dissolution phenomenon, and the like can be effectively suppressed. .

When the ratio of the Ni transition metal in the oxide represented by Chemical Formula 2 exceeds 0.65 (a> 0.65), since the excess Ni is included in the positive electrode active material, Li + 1 may also be formed by a layer formed of a component derived from LiFSI on the electrode surface. The ions and Ni +2 may not inhibit the cation mixing of ions.

In addition, when an excessive amount of Ni transition metal is included in the positive electrode active material, the nickel transition metal having a d-orbit should have an octahedral structure in coordination bond in an environment such as a high temperature according to the variation in the oxidation number of Ni, but the energy level is supplied by external energy supply. The order of is reversed, or the oxidation number is varied (disproportionation reaction) to form a distorted octahedron. As a result, the crystal structure of the positive electrode active material including the nickel transition metal is deformed to increase the probability of eluting nickel metal in the positive electrode active material.

As a result, the present inventors have confirmed that while producing a high output when the positive electrode active material including the oxide according to the range of the formula (2) and LiFSI salt combination, while showing a high efficiency in high temperature stability and capacity characteristics.

When the lithium secondary battery according to an example of the present invention includes an oxide represented by Formula 2 as a cathode active material, the lithium bisfluorosulfonylimide has a concentration in the non-aqueous electrolyte of 0.01 mol / L to 2 mol / L. It may be, specifically, may be 0.01 mol / L to 1 mol / L. When the concentration of the lithium bisfluorosulfonylimide is less than 0.1 mol / L, the effect of improving the low temperature output and the high temperature cycle characteristics of the lithium secondary battery is insignificant, and the concentration of the lithium bisfluorosulfonylimide is When the amount exceeds 2 mol / L, side reactions in the electrolyte may be excessively generated during charging and discharging of the battery, and a swelling phenomenon may occur, and corrosion of the positive electrode or the negative electrode current collector made of metal in the electrolyte may occur.

In order to further prevent such side reactions, the non-aqueous electrolyte of the present invention may further include lithium salts other than the lithium bisfluorosulfonylimide. The lithium salt may be used a lithium salt commonly used in the art, for example LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , CF ₃ SO ₃ Li, LiC (CF ₃ SO ₂ ) ₃ And LiC ₄ BO _{8 It} may be any one selected from the group consisting of or a mixture of two or more thereof.

When the lithium secondary battery according to an example of the present invention includes an oxide represented by Chemical Formula 2 as a cathode active material, a mixing ratio of the lithium salt and lithium bisfluorosulfonylimide is 1: 0.01 to 1: 1 day as molar ratio Can be. When the mixing ratio of the lithium salt and lithium bisfluoro sulfonyl imide is greater than or equal to the molar ratio, side reactions in the electrolyte may occur excessively during charging and discharging of the battery, and a swelling phenomenon may occur. In this case, output improvement of the generated secondary battery may be reduced. Specifically, when the mixing ratio of the lithium salt and lithium bisfluoro sulfonyl imide is less than 1: 0.01 as a molar ratio, a process of forming an SEI film in a lithium ion battery, and lithium ions solvated by a carbonate solvent are negative In the intervening process, a large number of irreversible reactions may occur, and by the peeling of the negative electrode surface layer (for example, the carbon surface layer) and the decomposition of the electrolyte, the low-temperature output of the secondary battery is improved, and the cycle characteristics and capacity after high-temperature storage. The effect of the improvement of properties may be insignificant. When the mixing ratio of the lithium salt and the lithium bisfluoro sulfonyl imide is a molar ratio, when the ratio is greater than 1: 1, lithium bisfluoro sulfonyl imide of excessive capacity is included in the electrolyte to prevent corrosion of the electrode current collector during charging and discharging. This may affect the stability of the secondary battery.

When the lithium secondary battery according to an example of the present invention includes an oxide represented by Chemical Formula 2 as a positive electrode active material, the non-aqueous solvent may minimize decomposition by an oxidation reaction or the like during charging and discharging of the battery, and together with an additive. Anything capable of exhibiting the desired properties can be used without limitation, for example, nitrile solvents, cyclic carbonates, linear carbonates, esters, ethers or ketones and the like can be used. These may be used alone, or two or more thereof may be used in combination.

Specifically, when the lithium secondary battery according to an example of the present invention includes an oxide represented by Formula 2 as a cathode active material, acetonitrile may be used as the non-aqueous solvent, and the lithium-nickel-manganese-cobalt oxide When the phosphorus positive electrode active material is used for the positive electrode, by using the acetonitrile-based solvent, it is possible to effectively prevent side effects due to deterioration in stability of the high output battery due to the combination with lithium bisfluoro sulfonyl imide.

Meanwhile, as the negative electrode active material, a carbon-based negative electrode active material such as crystalline carbon, amorphous carbon, or a carbon composite may be used alone or in combination of two or more thereof. Preferably, the crystalline carbon is graphite such as natural graphite and artificial graphite. (graphite) carbon.

Specifically, in the lithium secondary battery, the positive electrode or the negative electrode, for example, a mixture of a positive electrode or negative electrode active material, a conductive material and a binder on a positive electrode or negative electrode collector with a predetermined solvent to prepare a slurry, and then The slurry may be prepared by applying it on a current collector and then drying it.

According to one embodiment of the invention, the positive electrode current collector is generally made of a thickness of 3 ㎛ to 500 ㎛. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver or the like can be used.

The positive electrode current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The negative electrode current collector is generally made to a thickness of 3 μm to 500 μm. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, aluminum-cadmium alloy, and the like can be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The conductive material used in the positive electrode or negative electrode slurry is typically added in an amount of 1% to 20% by weight based on the total weight of the mixture including the positive electrode or the negative electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists the bonding of the positive electrode or the negative electrode active material and the conductive material to the current collector, and is generally added in an amount of 1% to 20% by weight based on the total weight of the mixture including the positive electrode or the negative electrode active material. . Examples of such binders include polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, and polymethylmethacrylate. ), Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM ), Various types of binder polymers such as sulfonated EPDM, styrene butyrene rubber (SBR), fluorine rubber, and various copolymers may be used.

In addition, preferred examples of the solvent include dimethyl sulfoxide (DMSO), alcohol, N-methylpyrrolidone (NMP), acetone or water, and the like, and are removed in a drying process.

The separator may be a conventional porous polymer film conventionally used as a separator, for example, a polyolefin type such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer The porous polymer film made of a polymer may be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used. no.

The battery case used in the present invention may be adopted that is commonly used in the art, there is no limitation on the appearance according to the use of the battery, for example, cylindrical, square, pouch (coin) or coin (can) using a can ( coin).

The lithium secondary battery according to the present invention may not only be used in a battery cell used as a power source for a small device, but also preferably used as a unit battery in a medium-large battery module including a plurality of battery cells. Preferred examples of the medium and large devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, power storage systems, and the like.

Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example

Although the following Examples and Experimental Examples will be further described, the present invention is not limited to these Examples and Experimental Examples.

Example 1

[Production of non-aqueous electrolyte solution]

Propylene carbonate (PC): Ethylene carbonate (EC): Ethyl methyl carbonate (EMC) LiPF ₆ based on the total amount of non-aqueous electrolyte as a lithium salt and a non-aqueous organic solvent having a composition of 3: 3: 4 (volume ratio). 0.1 mol / L was added, and 0.9 mol / L of lithium bisfluorosulfonylimide and 1% by weight of the compound of Formula 1 were added to prepare a non-aqueous electrolyte.

[Manufacture of Lithium Secondary Battery]

96% by weight of the mixture of LiMn ₂ O ₄ and Li (Ni _0.33 Co _0.33 Mn _0.33 ) O ₂ as the positive electrode active material, ₂ % by weight carbon black as the conductive material, 2% polyvinylidene fluoride (PVdF) as the binder % Was added to the solvent N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 μm, dried to prepare a positive electrode, and then subjected to roll press to prepare a positive electrode.

Further, a negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive material at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent. The negative electrode mixture slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of about 10 μm, dried to prepare a negative electrode, and then roll-rolled to prepare a negative electrode.

The positive electrode and the negative electrode prepared as described above were manufactured with a polymer battery by a conventional method with a separator composed of three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), followed by pouring the prepared non-aqueous electrolyte solution into a lithium secondary battery. The manufacture of the battery was completed.

Example 2

LiPF ₆ A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that the amounts were changed to 0.14 mol / L and 0.86 mol / L of lithium bisfluorosulfonylimide (about 1: 6 molar ratio). Was prepared.

Example 3

LiPF ₆ A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that the amounts were changed to 0.17 mol / L and 0.83 mol / L of lithium bisfluorosulfonylimide (about 1: 5 molar ratio). Was prepared.

Example 4

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.5 wt% of the compound of Formula 1 was used.

Example 5

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 2, except that the compound of Formula 1 was used at 0.5 wt%.

Example 6

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 2, except that the compound of Formula 1 was used at 3% by weight.

Comparative Example 1

Except for using ethylene carbonate (EC), a non-aqueous organic solvent having a composition of propylene carbonate (PC): ethylmethyl carbonate (DMC) 3: 7 (volume ratio) was used in the same manner as in Example 1 An aqueous electrolyte solution and a lithium secondary battery were prepared.

Comparative Example 2

In the same manner as in Example 1, except that a non-aqueous organic solvent having a composition of ethylene carbonate (EC): ethylmethyl carbonate (DMC) = 3: 7 (volume ratio) was used without using propylene carbonate (PC). A nonaqueous electrolyte solution and a lithium secondary battery were prepared.

Comparative Example 3

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that LiFSI and ortho-terphenyl were not used.

Comparative Example 4

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that LiFSI was not used.

Comparative Example 5

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the compound of Formula 1 was not used.

Experimental Example 1

<Measurement after high temperature storage>

The lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 were charged at 1 C up to 4.2 V / 38 mA under constant current / constant voltage (CC / CV) conditions at room temperature, and then 2.5 V under constant current (CC) conditions. It discharged at 2 C until the discharge capacity was measured, and it was set as the capacity of 0 weeks. Then, the lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 were stored at 60 ° C. for 18 weeks, and then charged at 1 C up to 4.2 V / 38 mA under constant current / constant voltage (CC / CV) conditions at room temperature. Then, the battery was discharged at 2 C up to 2.5 V under constant current (CC) conditions, and the discharge capacity thereof was measured to be 18 weeks later.

The capacity after high temperature storage was calculated as the capacity of 100 weeks / capacity at week 0 Ⅹ100 and is shown in Table 1 as a% value.

Experimental Example 2

<Output measurement after high temperature storage>

The low temperature output was calculated from the voltage difference generated by discharging the lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 from SOC (charge depth) of 50 to 5C at room temperature for 10 seconds, and the output was set to the output of week 0. . Next, the lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 were stored at 60 ° C. for 18 weeks, and then discharged at 5 ° C. at 50% of SOC (charge depth) for 10 seconds at low temperature. The output was calculated, and the output was taken after 18 weeks.

The output after high temperature storage was calculated as the output of 100 weeks after the output of Week 18 / output # 100 and is shown in Table 1 as a% value.

Experimental Example 3

<Measurement of battery thickness increase rate>

The thicknesses of the lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 were measured, and the thickness after storage at 60 ° C. for 18 weeks was measured to determine the battery thickness increase rate (thickness of thickness / week 0 after 18 weeks × 100 It is shown in Table 1 as a% value calculated as) -100.

Experimental Example 4

<Life temperature measurement>

The lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 were charged at 1 ° C. up to 4.2 V / 38 mA at 25 ° C. under constant current / constant voltage (CC / CV) conditions, and then 2.5 at constant current (CC) conditions. It discharged at 2 C to V, and the discharge capacity was measured. This was repeated 1 to 1000 cycles, and the value calculated as (capacity after 1000 cycles / capacity after cycle 1) × 100 is shown in Table 1 below as a normal temperature life characteristic.

Experimental Example 5

<High temperature life measurement>

The lithium secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 5 were charged at 1 C up to 4.2 V / 38 mA under constant current / constant voltage (CC / CV) conditions at 45 ° C., followed by 2.5 under constant current (CC) conditions. It discharged at 2 C to V, and the discharge capacity was measured. This was repeated 1 to 1000 cycles, and the value calculated as (capacity after 1000 cycles / capacity after cycle 1) × 100 is shown in Table 1 below as a high temperature life characteristic.

	LiPF 6 : LiFSI	Additive (% by weight)	High Temperature Storage Characteristics (%)			Life characteristic (%)
			Volume	Print	Battery thickness increase	Room temperature	High temperature
Example 1	1: 9	One	83.1	90.2	5.4	84.3	78.7
Example 2	1: 6	One	84.8	91.6	5.7	86.9	81.2
Example 3	1: 5	One	84.4	89.9	6.3	83.5	78.5
Example 4	1: 9	0.5	83.8	92.1	6.7	84.7	80.4
Example 5	1: 6	0.5	84.6	92.0	6.6	86.4	82.3
Example 6	1: 6	3	80.8	64.5	10.0	67.5	62.8
Comparative Example 1	1: 9	One	75.2	78.8	14.8	77.8	75.2
Comparative Example 2	1: 9	One	76.8	79.1	23.7	80.6	77.1
Comparative Example 3	1: 0	0	68.7	69.9	21.8	69.7	62.8
Comparative Example 4	1: 0	One	70.7	79.1	20.2	78.6	71.7
Comparative Example 5	1: 9	0	79.7	83.7	10.2	80.4	78.0

The additive in Table 1 represents a pyridine-based compound of formula (1).

As can be seen through Table 1, the lithium secondary batteries of Examples 1 to 6 are lithium bisfluorosulfonyl imide together with a non-aqueous organic solvent including propylene carbonate (PC) and ethylene carbonate (EC). And a pyridine-based compound, Comparative Example 1, which does not include ethylene carbonate (EC) as a non-aqueous organic solvent, Comparative Example 2, which does not include propylene carbonate (PC) as a non-aqueous organic solvent, lithium bisfluorosulfonyl Compared with the lithium secondary battery of Comparative Example 3, which does not contain an imide and a pyridine-based compound, and Comparative Example 4, which does not contain lithium bisfluorosulfonylimide, exhibits high capacity and output even after high temperature storage, and shows a battery thickness increase rate. It also shows a small value, which shows excellent high temperature storage characteristics, and also maintains high capacity even after 1000 cycles at room temperature and high temperature. The person exhibits characteristics could be confirmed.

On the other hand, looking at the effects of the addition of lithium bisfluorosulfonylimide, when comparing the lithium secondary batteries of Example 1 and Comparative Example 4, which differ only in the addition of lithium bisfluorosulfonylimide, It was confirmed that the lithium secondary battery of Example 1 exhibited excellent excellent high temperature storage characteristics and life characteristics according to the addition of lithium bisfluorosulfonylimide. In addition, looking at the effect of the addition amount of lithium bisfluorosulfonylimide, in the case of the lithium secondary battery of Example 1 LiPF ₆ : LiFSI is 1: 9 ratio, Example 3 having a ratio of 1: 5 Compared with the lithium secondary battery of the excellent high temperature storage characteristics and life characteristics. In addition, the lithium secondary battery of Example 2 having a LiPF ₆ : LiFSI ratio of 1: 6 was also compared with the lithium secondary battery of Example 3, except that the shelf life characteristic value was slightly lower than that of the lithium secondary battery of Example 3, In general, it was confirmed that exhibited excellent high temperature storage characteristics and life characteristics.

In addition, looking at the effect of the addition of the pyridine-based compound, when comparing the lithium secondary battery of Examples 1 and 4 and Comparative Example 5, which differ only in the addition of the pyridine-based compound, the lithium secondary battery of Examples 1 and 4 When the addition of the compound of the formula (1) showed more excellent high temperature storage characteristics and life characteristics, it was confirmed that the rate of increase in battery thickness is also significantly low.

On the other hand, when looking at the effect of the addition amount of the pyridine-based compound, in the case of Examples 1 to 5 containing 0.5 to 1% by weight of the compound of Formula 1 relative to the total weight of the non-aqueous electrolyte 3% by weight of the compound of Formula 1 It showed a superior effect compared to Example 6 included.

Example 7

Preparation of Electrolyte

Ethylene carbonate (EC): Non-aqueous organic solvent and lithium salt having a composition of ethyl methyl carbonate (EMC) 3: 7 (volume ratio), LiPF ₆ based on the total amount of the non-aqueous electrolyte. 0.9 mol / L was added, and 0.1 mol / L of lithium bisfluorosulfonylimide and 1% by weight of the compound of Formula 1 were added to prepare a non-aqueous electrolyte.

[Manufacture of Lithium Secondary Battery]

92% by weight of Li (Ni _0.6 Co _0.2 Mn _0.2 ) O ₂ as a positive electrode active material, 4% by weight of carbon black as a conductive material, and 4% by weight of polyvinylidene fluoride (PVdF) as a binder, N-methyl as a solvent A positive electrode mixture slurry was prepared by adding to 2-pyrrolidone (NMP). The positive electrode mixture slurry was applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 μm, dried to prepare a positive electrode, and then subjected to roll press to prepare a positive electrode.

Further, a negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive material at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent. The negative electrode mixture slurry was applied to a thin film of copper (Cu), which is a negative electrode current collector having a thickness of 10 μm, and dried to prepare a negative electrode, followed by a roll press to prepare a negative electrode.

The positive electrode and the negative electrode prepared as described above were manufactured with a polymer battery by a conventional method with a separator composed of three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), followed by pouring the prepared non-aqueous electrolyte solution into a lithium secondary battery. The manufacture of the battery was completed.

Example 8

LiPF ₆ A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 7, except that the amount thereof was changed to 0.7 mol / L and 0.3 mol / L of lithium bisfluorosulfonylimide.

Example 9

LiPF ₆ A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 7, except that the amount thereof was changed to 0.6 mol / L and 0.4 mol / L of lithium bisfluorosulfonylimide.

Example 10

LiPF ₆ A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 7, except that the amount was changed to 0.5 mol / L and 0.5 mol / L of lithium bisfluorosulfonylimide.

Example 11

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 7, except that the compound of Formula 1 was used at 3% by weight.

Comparative Example 6

LiPF ₆ A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 7, except that the amount thereof was changed to 0.4 mol / L and 0.6 mol / L of lithium bisfluorosulfonylimide.

Comparative Example 7

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 8 except that the compound of Formula 1 was not used.

Comparative Example 8

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 8 except that Li (Ni _0.5 Co _0.3 Mn _0.2 ) O ₂ was used as the cathode active material.

Comparative Example 9

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 8 except that Li (Ni _0.8 Co _0.1 Mn _0.1 ) O ₂ was used as the cathode active material.

Comparative Example 10

A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 8 except that LiCoO ₂ was used as the cathode active material.

Experimental Example 6

<High temperature life measurement>

The lithium secondary batteries prepared in Examples 7 to 11 and Comparative Examples 6 to 10 were charged at 1 C up to 4.2 V / 38 mA under constant current / constant voltage (CC / CV) conditions at 45 ° C., followed by constant current (CC) conditions. Was discharged at 2 C to 2.5 V, and the discharge capacity thereof was measured. This was repeated 1 to 1000 cycles, and the value calculated as (capacity after 1000 cycles / 1 capacity after cycle) × 100 is shown in Table 2 as a high temperature life characteristic.

Experimental Example 7

Capacity characteristics after high temperature storage

The secondary batteries prepared in Examples 7 to 11 and Comparative Examples 6 to 10 were charged at 1 C to 4.2 V / 38 mA under constant current / constant voltage (CC / CV) conditions, and then to 2.5 V under constant current (CC) conditions. It discharged at 2 C, and the discharge capacity was measured. After 16 weeks of storage at 60 ° C., the secondary batteries were charged to 1 C up to 4.2 V / 38 mA at constant temperature / constant voltage (CC / CV), respectively, at room temperature, and then to 2.5 V under constant current (CC) conditions. It discharged at 2 C, and the discharge capacity was measured. The results obtained by calculating the discharge capacity after 16 weeks as a percentage (discharge capacity after 16 weeks / initial discharge capacity × 100 (%)) based on the initial discharge capacity are shown in Table 2 below.

Experimental Example 8

<Output characteristics after high temperature storage>

The secondary battery manufactured in Examples 7 to 11 and Comparative Examples 6 to 10 was calculated using the voltage difference generated when charging and discharging for 10 seconds at room temperature after 5 weeks at 60 ℃ for 16 weeks. The results obtained by calculating the output after 16 weeks as a percentage (16 weeks output (W) / initial output (W) x 100 (%)) based on the initial output amount are shown in Table 2 below. The test was performed at 50% SOC (state of charge).

Experimental Example 9

<Measurement of battery thickness increase rate>

The thicknesses of the secondary batteries prepared in Examples 7 to 11 and Comparative Examples 6 to 10 were measured, and the thicknesses after storage for 16 weeks at 60 ° C. were measured, and (thickness after 16 weeks / thickness of 0 weeks × 100) -100 The calculated value is shown in Table 1 as a cell thickness increase rate.

	Cathode active material	LiPF 6 : LiFSI	Additive (% by weight)	High temperature life (%)	High Temperature Storage Characteristics (%)
					Volume	Print	thickness
Example 7	NMC622	9: 1	One	84.8	89.9	95.4	5.3
Example 8	NMC622	7: 3	One	89.2	92.8	96.7	4.1
Example 9	NMC622	6: 4	One	87.6	91.4	96.8	4.9
Example 10	NMC622	5: 5	One	86.7	90.9	94.2	5.2
Example 11	NMC622	3: 7	3	71.2	76.9	71.3	24.4
Comparative Example 6	NMC622	4: 6	One	83.1	88.7	95.2	6.1
Comparative Example 7	NMC622	7: 3	0	75.6	84.1	92.4	19.7
Comparative Example 8	NMC532	7: 3	One	71.7	80.5	88.6	31.8
Comparative Example 9	NMC811	7: 3	One	65.1	65.9	70.8	34.7
Comparative Example 10	LiCoO 2	7: 3	One	70.4	83.4	78.5	20.4

In Table 2, NMC622 is Li (Ni _0.6 Co _0.2 Mn _0.2 ) O ₂ , NMC532 is Li (Ni _0.5 Co _0.3 Mn _0.2 ) O ₂ , and NMC811 is Li (Ni _0.8 Co _0.1 Mn _0.1 ) O ₂ In addition, an additive represents the compound of General formula (1).

Looking at Table 2, Li (Ni _0.6 Co _0.2 Mn _0.2 ) O ₂ as a cathode active material, the mixing ratio of lithium salt and lithium bisfluoro sulfonyl imide is included in the range of 1: 0.01 to 1: 1 Secondary batteries of Examples 7 to 10 have a higher temperature than secondary batteries of Comparative Examples 8 and 9 containing Li (Ni _0.5 Co _0.3 Mn _0.2 ) O ₂ or Li (Ni _0.8 Co _0.1 Mn _0.1 ) O ₂ as a cathode active material. It was confirmed that the storage characteristics are excellent and the high temperature life is excellent.

In view of the addition of the pyridine-based compound, when comparing Example 8 and Comparative Example 7, the secondary battery of Example 8 including a non-aqueous electrolyte containing the compound of Formula 1 as a pyridine-based compound, Compared with Comparative Example 7 including a non-aqueous electrolyte solution containing no compound of 1, both the high temperature life and the high temperature storage characteristics were excellent.

Claims (18)

1. A non-aqueous electrolyte comprising a non-aqueous organic solvent, lithium bis (fluorosulfonyl) imide (LiFSI), and a pyridine-based compound represented by the following formula (1).

   [Formula 1]

   
2. The method of claim 1,

   The content of the pyridine-based compound represented by Formula 1 is 0.01% to 3% by weight based on the total weight of the nonaqueous electrolyte, nonaqueous electrolyte.
3. The method of claim 1,

   The lithium bis fluoro sulfonyl imide and the pyridine-based compound represented by Formula 1 is 1: 0.001 to 1: 5 by weight, non-aqueous electrolyte.
4. The method of claim 1,

   The non-aqueous organic solvent includes propylene carbonate (PC) and ethylene carbonate (EC),

   The mixing ratio of the propylene carbonate and ethylene carbonate is 1: 0.1 to 1: 2 by weight, non-aqueous electrolyte.
5. The method of claim 4, wherein

   The non-aqueous organic solvent is ethyl propionate (EP), methyl propionate (MP), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl Non-aqueous electrolyte further comprising any one selected from the group consisting of carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate (EPC), or a mixture of two or more thereof.
6. The method of claim 4, wherein

   The non-aqueous electrolyte further includes lithium salts other than the lithium bisfluorosulfonylimide,

   A non-aqueous electrolyte solution, wherein the mixing ratio of lithium salts other than the lithium bisfluorosulfonyl imide and lithium bisfluorosulfonyl imide is 1: 1 to 1: 9 in molar ratio.
7. The method of claim 6,

   Lithium salts other than the lithium bisfluorosulfonylimide are LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , CF _A non-aqueous electrolyte solution, which is any one selected from the group consisting of ₃ SO ₃ Li, LiC (CF ₃ SO ₂ ) _3, and LiC ₄ BO ₈ , or a mixture of two or more thereof.
8. The method of claim 4, wherein

   The content of the propylene carbonate is 5 parts by weight to 60 parts by weight based on 100 parts by weight of the total non-aqueous organic solvent, non-aqueous electrolyte.
9. The method of claim 4, wherein

   The lithium bisfluorosulfonylimide has a concentration in the non-aqueous electrolyte solution is 0.1 mol / L to 2 mol / L, the non-aqueous electrolyte.
10. A positive electrode including a positive electrode active material; A negative electrode including a negative electrode active material; A separator interposed between the positive electrode and the negative electrode; And

    Including the non-aqueous electrolyte of claim 1,

    The cathode active material comprises a manganese spinel-based active material, lithium metal oxide or a mixture thereof, lithium secondary battery.
11. The method of claim 10,

    The lithium metal oxide is selected from the group consisting of lithium-manganese oxide, lithium-nickel-manganese oxide, lithium-manganese-cobalt-based oxide and lithium-nickel-manganese-cobalt-based oxide, lithium secondary battery.
12. The method of claim 10,

    The lithium metal oxide is a lithium-nickel-manganese-cobalt-based oxide,

    The lithium-nickel-manganese-cobalt oxide includes a lithium secondary battery comprising an oxide represented by the following formula (1):

    [Formula 1]

    Li _{1 + x} (Ni _a Co _b Mn _c ) O ₂

    (In Formula 1, 0.55≤a≤0.65, 0.18≤b≤0.22, 0.18≤c≤0.22, -0.2≤x≤0.2, and x + a + b + c = 1.)
13. The method of claim 12,

    The non-aqueous electrolyte further includes lithium salts other than the lithium bisfluorosulfonylimide,

    A lithium secondary battery having a mixing ratio of lithium salts other than the lithium bisfluorosulfonyl imide and lithium bisfluorosulfonyl imide in a molar ratio of 1: 0.01 to 1: 1.
14. The method of claim 13,

    Lithium salts other than the lithium bisfluorosulfonylimide are LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , CF Lithium secondary battery which is any one selected from the group consisting of ₃ SO ₃ Li, LiC (CF ₃ SO ₂ ) ₃ and LiC ₄ BO ₈ or a mixture of two or more thereof.
15. The method of claim 12,

    The lithium bisfluorosulfonylimide has a concentration of 0.01 mol / L to 2 mol / L in the non-aqueous electrolyte, lithium secondary battery.
16. The method of claim 12,

    The non-aqueous organic solvent includes a nitrile-based solvent, linear carbonate, cyclic carbonate, ester, ether, ketone or a combination thereof.
17. The method of claim 16,

    The cyclic carbonate is any one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC) or a mixture of two or more thereof, and the linear carbonate is dimethyl carbonate (DMC) or diethyl Lithium secondary battery which is any one selected from the group consisting of carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate (EPC) or a mixture of two or more thereof .
18. The method of claim 16,

    The nitrile solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile and 4-fluorobenzonitrile And at least one lithium secondary battery selected from the group consisting of difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.