KR101496511B1 - Lithium secondary battery - Google Patents

Abstract

(여기서, R¹, R², R³는 각각 독립적으로 탄소수 1 내지 5인 알킬렌 또는 탄소수 2 내지 5인 알케닐렌이고, m은 서로 독립적으로 1 내지 5의 정수이다)에 관한 것이다.More particularly, the present invention relates to a lithium secondary battery comprising a lithium transition metal oxide Li _x M _y O ₂ (M is Ni _{1 -a b} Mn _a Co _b [0.05? A? 0.4, 0.1? _B ? , 0.4? 1-ab? 0.7], x + y? 2, 0.95? X? 1.05), or a mixture of Li _x M _y O ₂ and LiCoO ₂ ; A negative electrode comprising a negative electrode active material; Separation membrane; And a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and a dinitrile compound having an ether bond represented by the following Formula 1, which is an additive for an electrolyte:
[Chemical Formula 1]

(Wherein R ¹ , R ² and R ³ are each independently alkylene having 1 to 5 carbon atoms or alkenylene having 2 to 5 carbon atoms, and m is independently an integer of 1 to 5).

Description

[0001] Lithium secondary battery [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery capable of greatly suppressing the swelling phenomenon during high temperature storage of a lithium secondary battery.

Recently, interest in energy storage technology is increasing. As the application fields of cell phones, camcorders, notebook PCs, and electric vehicles further expand, there is a growing demand for higher energy density of batteries used as power sources for such electronic devices. Lithium secondary batteries are the ones that can best meet these demands, and researches on them are actively under way.

Among the currently applied secondary batteries, the lithium secondary batteries developed in the early 1990s include a cathode made of a carbon material capable of absorbing and desorbing lithium ions, a cathode made of a lithium-containing oxide, and a mixed organic solvent, And a non-aqueous electrolytic solution.

However, a lithium secondary battery using a lithium transition metal oxide or a composite oxide is disadvantageous in that the metal component is detached from the anode of the battery when the battery is stored at a high temperature in a fully charged state, thereby being in a thermally unstable state.

On the other hand, organic solvents widely used in non-aqueous electrolytic solutions at present include ethylene carbonate, propylene carbonate, dimethoxyethane, gamma butyrolactone, N, N-dimethylformamide, tetrahydrofuran or acetonitrile. Such an organic solvent generally causes a so-called swelling phenomenon in which the battery is swollen by promoting decomposition due to oxidation of the electrolyte, for example, when stored at a high temperature for a long period of time. As a result, the battery life and charging / discharging efficiency are rapidly lowered, and in some cases, the battery is deteriorated and the safety of the battery is greatly reduced.

Various nitrile-based compounds have been proposed to solve these problems, but the swelling phenomenon can not be effectively solved.

In order to solve the above problems, the present invention provides a lithium secondary battery comprising a lithium transition metal oxide or a composite oxide as a positive electrode, wherein a specific non-aqueous electrolyte is added to the lithium secondary battery to reduce the swelling phenomenon And to provide a secondary battery.

In order to achieve the above object, the present invention provides a lithium transition metal oxide Li _x M _y O ₂ (M is Ni _1-ab Mn _a Co _b [0.05? A? 0.4, 0.1? _B? 0.4, 0.4? 1-ab Lt; = 0.7, x + y = 2, 0.95? X? 1.05), or a mixture of Li _x M _y O ₂ and LiCoO ₂ ; A negative electrode comprising a negative electrode active material; Separation membrane; And a non-aqueous electrolyte containing a lithium salt, an organic solvent, and a dinitrile compound having an ether bond represented by the following general formula (1), which is an additive for an electrolyte.

[Chemical Formula 1]

Wherein R ¹ , R ² and R ³ are independently alkylene having 1 to 5 carbon atoms or alkenylene having 2 to 5 carbon atoms, and m is independently an integer of 1 to 5.

According to the present invention, a non-aqueous electrolytic solution containing a lithium transition metal oxide, a compound containing a vinylene group or a vinyl group, and a dinitrile compound having an ether bond is used together to inhibit gas generation at high temperature storage to prevent battery swelling And the charge / discharge cycle life can be improved.

1 is a graph showing changes in thickness of lithium secondary batteries according to Examples 1 and 2 and Comparative Examples 1 and 2 according to storage time according to storage time.
2 is a graph showing changes in discharge capacity according to the number of cycles of the lithium secondary battery of Example 3 and Comparative Example 3 according to the present invention.

The present invention is a lithium transition metal oxide is Li _x M _y O ₂ (M is _{Ni 1 -a- b Mn a Co b} [0.05≤a≤0.4, 0.1≤b≤0.4, 0.4≤1-ab≤0.7], x + y? 2, 0.95? x? 1.05), or a mixture of Li _x M _y O ₂ and LiCoO ₂ ;

A negative electrode comprising a negative electrode active material;

Separation membrane; And

A lithium secondary battery comprising a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and a dinitrile compound having an ether bond represented by the following Formula 1, which is an additive for an electrolyte:

[Chemical Formula 1]

Wherein R ¹ , R ² and R ³ are each independently an alkylene having 1 to 5 carbon atoms or an alkenylene having 2 to 5 carbon atoms, and m is independently an integer of 1 to 5).

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

In the lithium secondary battery according to the present invention, the cathode active material is a lithium transition metal oxide Li _x M _y O ₂ (M is Ni _{1 -a b} Mn _a Co _b [0.05? A? 0.4, 0.1? _B? X + y? 2, and 0.95? X? 1.05), or by mixing Li _x M _y O ₂ and LiCoO ₂ at 20-30: 80-70, Improve capacity and cycle stability, and improve storage stability and high temperature stability. When LiCoO ₂ is less than 70 wt% in the mixing ratio of Li _x M _y O ₂ and LiCoO ₂ , there is a problem of high-temperature cycle characteristics. When the mixing ratio is more than 80 wt%, the effect of improving the capacity of the secondary battery is small.

At this time, it is preferable that the total mole fraction (1-ab) of the nickel (Ni) is a mole fraction including Ni ^{2 +} and Ni ^{3 +} , and is 0.4-0.7 in which nickel is excessively contained relative to manganese and cobalt. When the molar fraction of nickel is less than 0.4, the capacity is not improved. When it exceeds 0.7, the safety of the battery is lowered.

The Li _x M _y O ₂ Or in a mixture of Li _x M _y O ₂ and LiCoO ₂ , Ni ^{2 +} and Ni ³⁺ preferably coexist in the MO layer, and some Ni ^{2 +} is inserted in the intercalation / deintercalation layer (reversible lithium layer) . Since Ni ^{2 +} is very similar in size to lithium ion (Li ⁺ ), it is inserted into the reversible lithium layer and does not deform the crystal structure. When the lithium ions are removed during charging, the repulsive force of the transition metal oxide layer It is possible to prevent the crystal structure from collapsing. Therefore, it is preferable that Ni ^{2 + be} contained at least so as to stably support at least between the MO layers, and it is possible to prevent degradation of the rate characteristic by inserting the Ni ^{2 +} in such a degree that it does not interfere with the occlusion and release of lithium ions in the reversible lithium layer have. In other words, the mole fraction of Ni ^{2 +} into the reversible lithium layer is too high, increase in the insertion of the Ni ^{2 +} to form a rock salt structure (rock salt structure) with no electrochemical reactions locally, so not only interfere with the charging and discharging The Accordingly, the discharge capacity can be reduced. Therefore, the molar fraction of Ni ^{2 +} inserted into the reversible lithium layer is preferably 0.03 - 0.07 with respect to the total amount of Ni.

The mole fraction (b) of cobalt (Co) is preferably 0.1 to 0.4, and when it is less than 0.1, sufficient rate characteristics and high powder density of the battery can not be achieved at the same time. The cost is increased and the reversible capacity is somewhat reduced.

The mole fraction (x) of lithium (Li) is preferably from 0.95 to 1.05, and when it is less than 0.95, the rate characteristic decreases and the reversible capacity decreases. 4.35 V), the stability is lowered during the cycle.

Further, as the ratio of Li to the transition metal (M) is lower, the amount of Ni inserted into the MO layer gradually increases, and when too much amount falls to the reversible lithium layer, The movement of Li ^{< + &gt}; is disturbed and the reversible capacity is decreased or the rate characteristic is lowered. On the contrary, when the ratio of Li / M is too high, the amount of Ni inserted in the MO layer is too small to cause structural instability, which may result in deterioration of battery stability and deterioration of lifetime characteristics. In addition, at an excessively high value of Li / M, the amount of unreacted Li ₂ CO ₃ increases, so that a large amount of impurities are generated, and the chemical resistance and high temperature stability of the battery may be deteriorated.

The Li _x M _y O ₂ may be an agglomerated structure having an aggregate of fine powders and having an internal void. The flocculated structure maximizes the surface area reacted with the electrolytic solution to have a high rate characteristic and increase the reversible capacity of the anode.

Also, the LiCoO ₂ may be included in the cathode active material in a form in which a part of cobalt is not substituted (doped) with other elements, and may preferably be a monolithic structure. As a result, the stability of the crystal grains is improved as the size of the particles increases, and the manufacturing process of the lithium secondary battery including the same is facilitated, thereby improving the process efficiency.

In the lithium secondary battery according to the present invention, the anode active material may be a carbonaceous material, lithium metal, silicon, or tin, from which lithium ions can be occluded and released, and may be formed of TiO ₂ having a potential with respect to lithium of less than ₂ V, Metal oxides such as SnO ₂ are also possible. Preferably, carbon materials can be used, and carbon materials such as low-crystallinity carbon and high-crystallinity carbon can be used. Examples of low crystalline carbon are soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, High-temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes are representative .

The anode and / or the cathode may include a binder, and examples of the binder include vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile ), Polymethylmethacrylate, or an aqueous binder such as styrene-butadiene rubber (SBR) may be used together with a thickener such as carboxymethylcellulose (CMC). Preferably an aqueous binder which exhibits excellent adhesion even when only a relatively small amount is used because of its excellent adhesive strength.

The separator may be a conventional porous polymer film used as a conventional separator, for example, a polyolefin such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer A porous polymer film made of a high molecular weight polymer may be used alone or in a laminated manner, or a nonwoven fabric made of a conventional porous nonwoven fabric such as a glass fiber having a high melting point, a polyethylene terephthalate fiber or the like may be used. It is not.

In the lithium secondary battery according to the present invention, the non-aqueous electrolyte includes a lithium salt, an organic solvent, and a dinitrile compound having an ether bond represented by the following Formula 1, which is an electrolyte additive.

[Chemical Formula 1]

(Wherein R ¹ , R ² and R ³ are each independently an alkylene having 1 to 5 carbon atoms or an alkenylene having 2 to 5 carbon atoms, and m is an integer of 1 to 5,

The anion of the lithium salt is selected from the group consisting of F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N (CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (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 -, CF 3 CF 2 SO 3 -, (CF 3 ^{_{SO 2) 2 N -, (}} FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 6) 3 C -, (CF 3 SO 2 _{^{) 3 C -, CF 3 (}} CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN - 1 kind selected from the group consisting of ^- and _{(CF 3 CF 2 SO 2)} 2 N Can be used.

The organic solvent may be a mixed solution of a cyclic carbonate and a linear carbonate. Specifically, the organic solvent may be selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, dipropyl carbonate, dimethylsulfoxide, acetonitrile, At least one selected from the group consisting of ethane, diethoxyethane, vinylene carbonate, sulfolane, gamma-butyrolactone, propylene sulfite and tetrahydrofuran can be used.

The dinitrile compound having an ether bond is preferably contained in an amount of 0.1 to 10% by weight of the nonaqueous electrolytic solution. When the content is less than 0.1% by weight, there is a problem that the storage capacity at high temperature is low. When the content exceeds 10% by weight, the viscosity of the electrolyte increases and the high rate characteristic (supply of a high output current while maintaining the voltage) there is a problem.

Also, the above-mentioned dinitrile compound having an ether bond may be used in combination with 3,5-dioxy-heptanedinitrile, 1,4-bis (cyanoethoxy) butane, bis (2- cyanoethyl) (2-cyanoethyl) ether, diethylene glycol bis (2-cyanoethyl) ether, triethylene glycol bis (2-cyanoethyl) ether, tetraethylene glycol bis (2-cyanoethyl) ether, 3,6,9,12,15,18-hexaoxaicoic acid dinitrile, 1,3- Bis (2-cyanoethoxy) pentane, and ethylene glycol bis (4-cyanobutyl) ether, May be used.

In the lithium secondary battery according to the present invention, a compound containing a vinylene group or a vinyl group as an electrolyte additive may be further included.

The vinylene or vinyl group-containing compound may be contained in an amount of 1 to 10% by weight, preferably 1 to 7% by weight, more preferably 1 to 5% by weight of the non-aqueous electrolyte. If the content is less than 1% by weight, the swelling improvement effect is insignificant in a high temperature environment, and if the content is more than 10% by weight, the high-rate characteristics due to the increase in the viscosity of the electrolyte decrease.

The vinylene group or the vinyl group-containing compound may be respectively defined as -CH = CH- and CH ₂ = CH-, and examples of the vinylene or vinyl group-containing compound include vinylene carbonate- At least one member selected from the group consisting of a carboxylate compound, a carboxylate compound, a carboxylate compound, a carboxylate compound, a carboxylate compound, a carboxylate compound,

In addition, The compound containing a vinylene group may be represented by the following formula (2)

(2)

(Wherein R ⁴ and R ⁵ are each independently hydrogen or halogen, or C ₁ - an alkyl group of C _6, C ₆ - a C ₁₂ aryl group, C ₂ - C ₆ alkenyl or sulfonate group).

In addition, at least one of R ⁴ and R ⁵ in Formula 2 may include a vinyl group.

Further, in the lithium secondary battery according to the present invention, the non-aqueous electrolyte may further include a cyclic carbonate substituted with a halogen represented by the following formula (3):

(3)

Wherein X and Y are each independently hydrogen, chlorine or fluorine, and X and Y are not simultaneously hydrogen.

The cyclic carbonate substituted with a halogen may be used together with the vinylene or vinyl group-containing compound to improve the physical properties of the SEI film formed on the surface of the negative electrode, thereby further enhancing the anti-swelling effect of the battery.

The content of the halogen-substituted cyclic carbonate is preferably 1 to 10% by weight of the non-aqueous electrolyte. The mixing ratio of the compound containing a vinylene group or a vinyl group to the cyclic carbonate substituted by a halogen may be suitably selected according to the specific application in which the battery is used and may be, for example, a cyclic carbonate: vinylene group or a vinyl group substituted with a halogen Compound = 1: 0.5 - 5, but the present invention is not limited thereto. If the weight ratio of the vinylene group or the vinyl group-containing compound to the cyclic carbonate substituted with halogen is less than 0.5, the charge and discharge performance at high temperature is weakened. If the weight ratio exceeds 5, the interfacial resistance of the negative electrode is greatly increased, do. This is presumably because a compound containing a vinylene group or a vinyl group forms a relatively dense SEI film, but should not be construed to be limited thereto.

The organic solvent used in the non-aqueous electrolyte of the conventional lithium secondary battery is oxidized and decomposed on the surface of the anode during charging and discharging. In particular, when the lithium transition metal oxide is used as the cathode active material, the transition metal promotes the decomposition of the electrolytic solution by acting as the oxidant, and at the high temperature, the oxidative decomposition reaction is further accelerated.

However, since the dinitrile compound having an ether bond according to the present invention forms a complex on the surface of a positive electrode composed of a lithium transition metal oxide, the oxidation reaction of the nonaqueous electrolyte and the positive electrode is suppressed to suppress heat generation, An internal short circuit can be prevented. In addition, various compounds are present in the non-aqueous electrolyte during the charging / discharging process, and HF, PF ₆ or the like in the non-aqueous electrolyte causes the non-aqueous electrolyte to be in an acidic atmosphere. Oxygen (-O-) in the dinitrile compound having ether bond, in HF, it is possible to suppress the non-aqueous composition of the acidic environment inhibits the oxidative decomposition reaction of the electrolytic solution by combination with PF _6. Furthermore, the performance of the secondary battery can be improved as compared with the conventional additives. Specifically, the capacity retention rate is excellent and the charge / discharge cycle life can be improved.

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

Therefore, the lithium secondary battery according to the present invention can suppress the generation of gas during high-temperature storage by using a non-aqueous electrolyte containing a lithium transition metal oxide, a compound containing a vinylene group or a vinyl group and a dinitrile compound having an ether bond, The ring phenomenon can be prevented, and the charge / discharge cycle life can be improved.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention is not limited to the above-described embodiments.

Example 1:

Manufacture of anode

About 1 to the average particle diameter of 2 ㎛ minute particles about 5 ~ 8 ㎛ the aggregates of the _{(D 50) LiNi 0.53 Co 0.2} Mn 0.27 O 2 and, provided that the average particle diameter of approximately 15 ~ 20 ㎛ a daily structure (D ₅₀ with ) with a LiCoO ₂ positive active material was prepared by mixing in a ratio of 30:70.

Super P as a conductive material and polyvinylidene fluoride as a binder were mixed at a weight ratio of 92: 4: 4 and then NMP (N-methyl pyrrolidone) was added to prepare the slurry. The positive electrode slurry prepared above was applied to an aluminum current collector and dried in a vacuum oven at 120 ° C to prepare a positive electrode.

Preparation of non-aqueous electrolyte

1M LiPF ₆ solution having a composition of EC: PC: DEC = 3: 2: 5 was used as an electrolytic solution and 2 wt% of vinylene carbonate (VC), 3 wt% of fluoroethylene carbonate (FEC) 3% by weight of bis (2-cyanoethyl) ether was added thereto to prepare a non-aqueous electrolyte.

Manufacture of lithium secondary battery

Artificial graphite was used as an anode active material, a lithium polymer battery was manufactured by a conventional method, and an aluminum laminate packing material was used. Then, the electrolyte solution prepared above was injected into the assembled lithium secondary battery to complete the lithium secondary battery.

Example 2:

A lithium secondary battery was prepared in the same manner as in Example 1 except that ethylene glycol bis (2-cyanoethyl) ether was added in an amount of 5% by weight.

Example 3:

And the above embodiment except that a positive active material of about 1 ~ 2 ㎛ of the micro-particle aggregate of _{LiNi 0 .53 Co 0 .2 Mn 0} .27 O 2 having an average particle diameter (D ₅₀₎ of from about 5 ~ 8 ㎛ of only A lithium secondary battery was produced in the same manner as in Example 1.

Comparative Example 1:

A lithium secondary battery was prepared in the same manner as in Example 1, except that ethylene glycol bis (2-cyanoethyl) ether was not added to the nonaqueous electrolyte solution.

Comparative Example 2;

A lithium secondary battery was prepared in the same manner as in Example 1 except that 5 wt% of succinonitrile was used instead of ethylene glycol bis (2-cyanoethyl) ether in the non-aqueous electrolyte.

Comparative Example 3:

Only about _{1 ~ 2 ㎛ LiNi 0 .53 Co} 0 .2 Mn 0 .27 O 2 having an average particle diameter (D ₅₀₎ of from about 5 ~ 8 ㎛ of aggregates of fine particles of a positive electrode active material, and ethylene in the non-aqueous electrolyte Lithium secondary battery was prepared in the same manner as in Example 1 except that 5 wt% succinonitrile was used instead of glycol bis (2-cyanoethyl) ether.

Experimental Example 1: High temperature stability test of lithium secondary battery

The lithium secondary batteries prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were fully charged at 4.2 V and stored at 90 ° C for 4 hours to determine the initial thickness of lithium secondary battery and the change in thickness after storage (Δt) And the results are shown in Table 1 and Fig.

Yes ? T (mm) Example 1 3.24 Example 2 2.52 Comparative Example 1 4.00 Comparative Example 2 3.95

As shown in Table 1, it can be seen that the secondary batteries of Examples 1 and 2 according to the present invention were suppressed in thickness increase (swelling phenomenon) during storage at a high temperature for a long time as compared with the secondary batteries of Comparative Examples 1 and 2 , And ethylene glycol bis (2-cyanoethyl) ether are superior to suinonitrile, which is a dinitrile compound, against swelling phenomenon.

Further, as shown in FIG. 1, as the storage time of the secondary battery of Example 2 according to the present invention increases, it is found that the thickness variation is smaller than that of the secondary batteries of Comparative Examples 1 and 2, Able to know.

Experimental Example 2: Evaluation of charge / discharge performance of lithium secondary battery

The lithium secondary batteries manufactured in Example 3 and Comparative Example 3 were charged at a constant current of 1 C = 980 mA at 45 캜. After the voltage of the battery reached 4.2 V, until the charge current value reached 50 mA at a constant voltage of 4.2 V Lt; / RTI > The discharge capacity of one cycle was measured by discharging the battery at a constant current of 1 C until the battery voltage reached 3V. Subsequently, the above charge and discharge cycles were repeated for 300 cycles, and the results are shown in FIG.

As shown in FIG. 2, the lithium secondary battery of Example 3 according to the present invention has an effect of improving the charge / discharge cycle life at a higher temperature than that of the lithium secondary battery of Comparative Example 3.

Claims (14)

Lithium transition metal oxide Li _x M _y O ₂ (M is Ni _{1 -ab} Mn _a Co _b [0.05? A? 0.4, 0.1? B? 0.4, 0.4? 1-ab? 0.7], x + y? , 0.95? _X? 1.05), or a mixture of Li _x M _y O ₂ and LiCoO ₂ ;
A negative electrode comprising a negative electrode active material;
Separation membrane; And
A lithium secondary battery comprising a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and a dinitrile compound having an ether bond represented by the following Formula 1, which is an additive for an electrolyte:
[Chemical Formula 1]

(Wherein R ¹ , R ² and R ³ are each independently alkylene having 1 to 5 carbon atoms or alkenylene having 2 to 5 carbon atoms, and m is an integer of 1 to 5 independently of one another).
The method according to claim 1,
The _x M _y O ₂ mixture with Li of LiCoO ₂ is Li _x M _y O ₂ with LiCoO ₂ is 20 - 30:80 - 70 wherein the lithium secondary battery of the mixture in a weight ratio of.
The method according to claim 1,
_Wherein Li _x M _y O ₂ (M is Ni _{1 -a b} Mn _a Co _b [0.05? A? 0.4, 0.1? B? 0.4, 0.4? 1-ab? 0.7], x + y? 0.95? _X? 1.05) or a transition metal oxide layer (MO layer) of the mixture of Li _x M _y O ₂ and LiCoO ₂ , and the molar fraction of Ni ^{2 +} in the lithium ion is a total amount of Ni 0.03 to 0.07 based on the total weight of the lithium secondary battery.
The method according to claim 1,
The anion of the lithium salt is selected from the group consisting of F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N (CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (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 -, CF 3 CF 2 SO 3 -, (CF 3 ^{_{SO 2) 2 N -, (}} FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 6) 3 C -, (CF 3 SO 2 _{^{) 3 C -, 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 - 1 species is selected from the group consisting of Lt; RTI ID = 0.0 > rechargeable < / RTI >
The method according to claim 1,
The organic solvent may be at least one selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, dipropyl carbonate, dimethylsulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, , Gamma-butyrolactone, propylene sulfite, and tetrahydrofuran.
The method according to claim 1,
Wherein the dinitrile compound having an ether bond is contained in an amount of 0.1 to 10% by weight of the non-aqueous electrolyte.
The method according to claim 1,
The above-mentioned dinitrile compound having an ether bond may be at least one compound selected from the group consisting of 3,5-dioxaheptanedinitrile, 1,4-bis (cyanoethoxy) butane, bis (2-cyanoethyl) (2-cyanoethyl) ether, diethylene glycol bis (2-cyanoethyl) ether, triethylene glycol bis (2-cyanoethyl) ether, diethylene glycol bis -Cyanoethyl) ether, tetraethylene glycol bis (2-cyanoethyl) ether, 3,6,9,12,15,18-hexaoxaicoic acid dinitrile, 1,3-bis Propane, 1,4-bis (2-cyanoethoxy) butane, 1,5-bis (2-cyanoethoxy) pentane and ethylene glycol bis (4-cyanobutyl) Wherein the lithium secondary battery is a lithium secondary battery.
The method according to claim 1,
Wherein the non-aqueous electrolyte additive further comprises a compound containing a vinylene group or a vinyl group.
The method of claim 8,
Wherein the vinylene group or the vinyl group-containing compound is contained in an amount of 1 - 10 wt% of the non-aqueous electrolyte.
The method of claim 8,
The vinylene or vinyl group-containing compound may be at least one selected from the group consisting of a vinylene carbonate-based compound, an acrylate-based compound containing a vinyl group, a sulfonate-based compound containing a vinyl group, and an ethylene carbonate- Lt; RTI ID = 0.0 >%.≪ / RTI >
The method of claim 8,
Wherein the vinylene group-containing compound is represented by the following general formula (2): < EMI ID =
(2)

(Wherein R < ⁴ > And R ⁵ each independently is hydrogen or halogen, optionally substituted by halogen or unsubstituted C ₁ - an alkyl group of C _6, C ₆ - a C ₁₂ aryl group, C ₂ - C ₆ alkenyl or sulfonate group).
The method of claim 11,
Wherein at least one of R ⁴ and R ⁵ in Formula 2 comprises a vinyl group.
The method according to claim 1 or 8,
Wherein the non-aqueous electrolyte further comprises a cyclic carbonate substituted with a halogen represented by the following formula (3): < EMI ID =
(3)

Wherein X and Y are each independently hydrogen, chlorine or fluorine, and X and Y are not simultaneously hydrogen.
14. The method of claim 13,
Wherein the halogen-substituted cyclic carbonate is contained in an amount of 1 - 10 wt% of the non-aqueous electrolyte.

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