KR101952428B1 - Electrolyte and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrolytic solution and a lithium secondary battery comprising the same, wherein the electrolytic solution contains a sulfanecarboxylic acid ester derivative as an electrolyte additive, and is characterized in that the battery characteristics, particularly charge / discharge characteristics at low temperatures, Can be improved.

Description

ELECTROLYTE AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to an electrolyte solution capable of improving the low-temperature charge-discharge characteristics and the room temperature recovery rate of a lithium secondary battery, and a lithium secondary battery comprising the electrolyte solution.

Lithium secondary batteries can be used not only as portable power sources such as mobile phones, notebook computers, digital cameras and camcorders but also as power tools, electric bicycles, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles HEV, PHEV), and the like.

As the application field is expanded and demand is increased, the external shape and size of the battery are variously changed, and performance and stability are demanded more than the characteristics required in the conventional small batteries. In order to meet such a demand, the performance of the battery should be stabilized in a condition where battery components are flowing in a large current.

The lithium secondary battery is manufactured by using a material capable of inserting and desorbing lithium ions as a cathode and an anode, providing a porous separator between the two electrodes, and injecting a liquid electrolyte. The insertion and extraction of lithium ions in the cathode and the anode, Electricity is generated or consumed by the redox reaction due to desorption.

Various non-aqueous solvents and additives as an electrolyte-containing component have been studied in order to improve the battery characteristics such as the output characteristics, cycle characteristics, and storage characteristics of the lithium secondary battery.

Further, even when a specific compound is added to an electrolyte solution as an additive for improving battery performance, improvement of performance of some items of most battery performance can be expected, but the performance of other items is rather reduced.

Patent registration No. 515298 (registered on September 8, 2005)

An object of the present invention is to provide an electrolyte capable of improving the battery characteristics, particularly the low temperature charge-discharge characteristics and the room temperature recovery rate, of a lithium secondary battery.

Another object of the present invention is to provide a lithium secondary battery comprising the electrolyte solution.

In order to achieve the above object, an electrolyte according to an embodiment of the present invention includes a sulfanecarboxylic acid ester derivative as an electrolyte additive.

The sulforanecarboxylic acid ester derivative may be a compound having a structure represented by the following formula (1).

[Chemical Formula 1]

(Wherein R is selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an acetate group, a (meth) acrylate group,

Preferably, the sulfolencarboxylic acid ester derivative may be methyl 3-sulfolene-3-carboxylate.

The sulfanecarboxylic acid ester derivative may be contained in an amount of 0.1 to 10% by weight based on the total weight of the electrolytic solution.

The electrolytic solution may further include an organic solvent and a lithium salt.

The organic solvent may be selected from the group consisting of an ester solvent, an ether solvent, a ketone solvent, an aromatic hydrocarbon solvent, an alkoxyalkane solvent, a carbonate solvent, and a mixture thereof.

The organic solvent may include an organic solvent having a high dielectric constant and a low viscosity organic solvent at a volume ratio of 2: 8 to 8: 2.

The high-k organic solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, and mixtures thereof. The low-viscosity organic solvent may be selected from the group consisting of methylethylcarbonate, dimethyl carbonate dimethylcarbonate, diethylcarbonate, and mixtures thereof.

The organic solvent may be an organic solvent selected from the group consisting of ethylene carbonate and propylene carbonate, one organic solvent selected from the group consisting of ethylmethyl carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 5: 1: 1 to 2: 5: 3 .

The lithium salt is _{LiPF 6, LiClO 4, LiAsF 6} , LiBF 4, LiSbF 6, LiAl0 4, LiAlCl 4, LiCF 3 SO 3, LiC 4 F 9 SO 3, LiN (C 2 F 5 SO 3) 2, LiN ( C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ . _{LiN (C a F 2a + 1} SO 2) (C b F 2b + 1 SO 2) ( However, a and b are natural numbers), LiCl, LiI, LiB ( C 2 O 4) 2 , and mixtures thereof Can be selected from the group.

According to another embodiment of the present invention, there is provided a lithium secondary battery including: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material disposed opposite to the positive electrode; and an electrolyte interposed between the positive electrode and the negative electrode, The electrolytic solution contains a sulfanecarboxylic acid ester derivative as an electrolyte additive.

Other details of the embodiments of the present invention are included in the following detailed description.

The electrolyte according to the present invention can improve the battery characteristics, especially the low temperature charge / discharge characteristics and the room temperature recovery rate of the lithium secondary battery.

1 is an exploded perspective view of a lithium secondary battery according to an embodiment of the present invention.
2 is a graph showing the results of evaluation of charging / discharging characteristics at low temperatures of the lithium secondary batteries of Example 1 and Comparative Example 1. Fig.
3 is a graph showing the results of evaluating the room temperature recovery rate characteristics of the lithium secondary batteries of Example 1 and Comparative Example 1. Fig.

The present invention is capable of various modifications and various embodiments and is intended to illustrate and describe the specific embodiments in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprises" or "having" are used to designate the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

As used herein, the term " combination thereof " means that two or more substituents are bonded to each other through a single bond or a linking group, or two or more substituents are condensed and connected.

As additives for improving the battery characteristics of conventional lithium secondary batteries, most of them were additives for improving the performance at high temperature or improving the performance at room temperature. However, an additive capable of simultaneously improving the performance at a high temperature and a low temperature is required in view of being a middle- or large-sized battery.

On the other hand, in the present invention, the use of a sulfonic carboxylic acid ester derivative as an electrolyte additive is characterized by improving the charging / discharging characteristics at low temperature as well as the room temperature recovery ratio.

That is, the electrolytic solution according to an embodiment of the present invention includes a sulfanecarboxylic acid ester derivative as an electrolyte additive.

Specifically, the sulforanecarboxylic acid ester derivative may be a compound having a structure represented by the following formula (1).

 [Chemical Formula 1]

In Formula 1, R is an alkyl group having 1 to 10 carbon atoms such as methyl, ethyl, n-propyl or n-butyl; A cycloalkyl group having 3 to 30 carbon atoms such as a cyclobutyl group, a cyclohexyl group, an adamantane group or a norbornyl group; An aryl group having 6 to 30 carbon atoms such as a phenyl group or a naphthalene group; Acetate groups; A (meth) acrylate group such as an acrylic group or a methacryl group; And combinations thereof.

The sulfolencarboxylic acid ester derivative as described above can improve the characteristics of the battery, particularly the low temperature charge / discharge characteristics and the room temperature recovery rate by forming a thin and dense SEI.

Among them, the sulfanecarboxylic acid ester derivative of Formula 1 is preferable because it can exhibit the low temperature charging / discharging characteristics and the room temperature recovery ratio of the improved lithium secondary battery when R is an alkyl group having 1 to 5 carbon atoms May be a methyl group, an ethyl group, an n-propyl group or an n-butyl group.

And most preferably Methyl 3-sulfolene-3-carboxylate represented by the following formula (2).

(2)

The sulfanecarboxylic acid ester derivative may be contained in an amount of 0.1 to 10% by weight based on the total weight of the electrolytic solution. When the content of the aromatic compound is less than 0.1% by weight, the effect of addition of the aromatic compound of the formula (1) is insignificant. When the content of the aromatic compound is more than 10% by weight, the life of the battery may be deteriorated. Preferably 0.1 to 5% by weight.

The electrolyte may further include an organic solvent and a lithium salt in addition to the electrolyte additive.

The organic solvent may be any organic solvent that can act as a medium through which ions involved in an electrochemical reaction of a battery can move. Specifically, examples of the organic solvent include an ester solvent, an ether solvent, a ketone solvent, an aromatic hydrocarbon solvent, an alkoxyalkane solvent, a carbonate solvent, etc. These solvents may be used singly or in combination of two or more.

Specific examples of the ester solvent include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, But are not limited to, ethyl propionate,? -Butyrolactone, decanolide,? -Valerolactone, mevalonolactone,? -Caprolactone (? -caprolactone, 隆 -valerolactone, 竜 -caprolactone, and the like.

Specific examples of the ether solvent include dibutyl ether, tetraglyme, 2-methyltetrahydrofuran, tetrahydrofuran, and the like.

Specific examples of the ketone-based solvents include cyclohexanone and the like. Specific examples of the aromatic hydrocarbon organic solvent include benzene, fluorobenzene, chlorobenzene, iodobenzene, toluene, fluorotoluene, xylene, (xylene), and the like. Examples of the alkoxyalkane solvent include dimethoxy ethane and diethoxy ethane.

Specific examples of the carbonate solvent include dimethylcarbonate (DMC), diethylcarbonate (DEC), dipropylcarbonate (DPC), methylpropylcarbonate (MPC), ethylpropylcarbonate (EPC) , Methyl ethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylenes carbonate (BC) And fluoroethylene carbonate (FEC).

Among them, a carbonate-based solvent is preferably used as the organic solvent. Among the carbonate-based solvents, a carbonate-based organic solvent having a high ionic conductivity having a high ion conductivity capable of enhancing the charge / discharge performance of the battery, It may be preferable to use a mixture of a carbonate-based organic solvent having a low viscosity which can appropriately control the viscosity of the organic solvent having a high electrical conductivity. Specifically, an organic solvent having a high dielectric constant selected from the group consisting of ethylene carbonate, propylene carbonate, and mixtures thereof, and an organic solvent having a low viscosity selected from the group consisting of ethylmethyl carbonate, dimethyl carbonate, diethyl carbonate, Can be mixed and used. More preferably, the organic solvent having a high dielectric constant and the organic solvent having a low viscosity are mixed at a volume ratio of 2: 8 to 8: 2, and more specifically, ethylene carbonate or propylene carbonate; Ethyl methyl carbonate; And dimethyl carbonate or diethyl carbonate in a volume ratio of 5: 1: 1 to 2: 5: 3, preferably 3: 5: 2.

The lithium salt can be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (C ₂ F ₅ SO ₃ ) _{2 , LiN (C 2 F 5 SO} 2) 2, LiN (CF 3 SO 2) 2. (A sweet, a, and b is a natural number, preferably a 1 = a = 20, 1 = b = 20 _{Im) LiN (C a F 2a +} 1 SO 2) (C b F 2b + 1 SO 2), LiCl, LiI, LiB (C ₂ O ₄ ) _2, and mixtures thereof. It is preferable to use lithium hexafluorophosphate (LiPF ₆ ).

When the lithium salt is dissolved in an electrolytic solution, the lithium salt functions as a source of lithium ions in the lithium secondary battery and can promote the movement of lithium ions between the anode and the cathode. Accordingly, it is preferable that the lithium salt is contained in the electrolytic solution at a concentration of approximately 0.6 mol% to 2 mol%. If the concentration of the lithium salt is less than 0.6 mol%, the conductivity of the electrolyte may be lowered and the performance of the electrolyte may be deteriorated. If the concentration exceeds 2 mol%, the viscosity of the electrolyte may increase and the mobility of the lithium ion may be lowered. Considering the conductivity of the electrolyte and the mobility of lithium ions, it is more preferable that the lithium salt is controlled to approximately 0.7 mol% to 1.6 mol% in the electrolyte solution.

The electrolytic solution further includes an additive (hereinafter referred to as "other additive") which can be generally used for electrolytic solution for the purpose of improving lifetime characteristics of the battery, suppressing reduction in battery capacity, improving discharge capacity of the battery, etc. can do.

Examples of the other additives include vinylene carbonate (vinylenecarbonate, VC), metal fluoride (metal fluoride, for example, LiF, RbF, TiF, AgF , AgF2, BaF 2, CaF 2, CdF 2, FeF 2, HgF ₂ , Hg ₂ F ₂ , MnF ₂ , NiF ₂ , PbF ₂ , SnF ₂ , SrF ₂ , XeF ₂ , ZnF ₂ , AlF ₃ , BF ₃ , BiF ₃ , CeF ₃ , CrF ₃ , DyF ₃ , EuF ₃ , GaF _{3, GdF 3, FeF 3,} HoF 3, InF 3, LaF 3, LuF 3, MnF 3, NdF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF 3, TmF 3, YF 3, _{YbF 3, TIF 3, CeF 4} , GeF 4, HfF 4, SiF 4, SnF 4, TiF 4, VF 4, ZrF4 4, NbF 5, SbF 5, TaF 5, BiF 5, MoF 6, ReF 6, SF 6 , WF ₆ , CoF ₂ , CoF ₃ , CrF ₂ , CsF, ErF ₃ , PF ₃ , PbF ₃ , PbF ₄ , ThF ₄ , TaF ₅ and SeF ₆ ), glutaronitrile Succinonitrile (SN), adiponitrile (AN), 3,3'-thiodipropionitrile (TPN), vinylethylene carbonate (VEC) Fluoroethylene carbo Fluoroethylene carbonate (FEC), difluoroethylenecarbonate, fluorodimethylcarbonate, fluoroethylmethylcarbonate, lithium bis (oxalato) borate, LiBOB ), Lithium difluoro (oxalate) borate, LiDFOB, lithium (malonato oxalato) borate, LiMOB) and the like. Of these, 1 Or a mixture of two or more species.

Examples of the other additives include vinylene carbonate (vinylenecarbonate, VC), metal fluoride (metal fluoride, for example, LiF, RbF, TiF, AgF , AgF2, BaF 2, CaF 2, CdF 2, FeF 2, HgF ₂ , Hg ₂ F ₂ , MnF ₂ , NiF ₂ , PbF ₂ , SnF ₂ , SrF ₂ , XeF ₂ , ZnF ₂ , AlF ₃ , BF ₃ , BiF ₃ , CeF ₃ , CrF ₃ , DyF ₃ , EuF ₃ , GaF _{3, GdF 3, FeF 3,} HoF 3, InF 3, LaF 3, LuF 3, MnF 3, NdF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF 3, TmF 3, YF 3, _{YbF 3, TIF 3, CeF 4} , GeF 4, HfF 4, SiF 4, SnF 4, TiF 4, VF 4, ZrF4 4, NbF 5, SbF 5, TaF 5, BiF 5, MoF 6, ReF 6, SF 6 , WF ₆ , CoF ₂ , CoF ₃ , CrF ₂ , CsF, ErF ₃ , PF ₃ , PbF ₃ , PbF ₄ , ThF ₄ , TaF ₅ and SeF ₆ ), glutaronitrile Succinonitrile (SN), adiponitrile (AN), 3,3'-thiodipropionitrile (TPN), vinylethylene carbonate (VEC) Fluoroethylene carbo Fluoroethylene carbonate (FEC), difluoroethylenecarbonate, fluorodimethylcarbonate, fluoroethylmethylcarbonate, lithium bis (oxalato) borate, LiBOB ), Lithium difluoro (oxalate) borate, LiDFOB, lithium (malonato oxalato) borate, LiMOB) and the like. Of these, 1 Or a mixture of two or more species.

The other additives may be included in an amount of 0.1 to 5% by weight based on the total weight of the electrolyte.

According to another embodiment of the present invention, there is provided a lithium secondary battery comprising the electrolyte solution. The lithium secondary battery according to an embodiment of the present invention can be classified into a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the type of the separator and the electrolyte used. The lithium secondary battery can be classified into a cylindrical shape, a square shape, Etc., and can be divided into a bulk type and a thin film type depending on the size. The electrolytic solution according to the embodiment of the present invention may be particularly excellent for application to a lithium ion battery, an aluminum laminated battery and a lithium polymer battery.

Specifically, the lithium secondary battery includes a cathode including a cathode active material disposed opposite to each other, a cathode including a cathode active material, and the electrolyte interposed between the anode and the cathode.

1 is an exploded perspective view of a lithium secondary battery 1 according to an embodiment of the present invention. 1, a lithium secondary battery 1 according to another embodiment of the present invention includes a separator 7 between a cathode 3, an anode 5, the cathode 3, and an anode 5, (5) and the separator (7) are impregnated with the electrolytic solution by placing the electrode assembly (9) in the case (15) have.

Conductive lead members 10 and 13 for collecting a current generated during a battery operation can be attached to the cathode 3 and the anode 5 respectively and the lead members 10 and 13 are respectively connected to the anode 5, And the current generated in the cathode (3) can be led to the positive electrode and the negative electrode terminal.

The anode 5 is prepared by mixing a cathode active material, a conductive agent and a binder to prepare a composition for forming a cathode active material layer, applying the composition for forming a cathode active material layer to a cathode current collector such as aluminum foil, can do.

As the cathode active material, a compound capable of reversibly intercalating and deintercalating lithium (a lithiated intercalation compound) can be used. Specifically, an olivine-type lithium metal compound represented by the following formula (3) can be used.

(3)

Li _x M _y M ' _z XO _4-w Y _w

M and M 'are independently Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B, And X is an element selected from the group consisting of P, As, Bi, Sb, Mo, and combinations thereof, and Y is selected from the group consisting of F, S, and combinations thereof 0 <x? 1, 0 <y? 1, 0 <z? 1, 0 <x + y + z? 2, and 0? W?

Among these compounds, LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _x Mn _(1-x) O ₂ (where 0 <x <1) and LiM _lx M _2y O ₂ (However, 0≤x≤1, 0≤y≤1, 0≤x + y≤1 , M 1 and M ₂ is one selected from the group consisting of Al, Sr, Mg and La are each independently One), and a mixture thereof.

The negative electrode 3 is prepared by mixing a negative electrode active material, a binder and an optional conductive agent in the same manner as the positive electrode 5 to prepare a composition for forming a negative electrode active material layer and then applying the composition to a negative electrode current collector such as a copper foil .

As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples of the negative electrode active material include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber and amorphous carbon. Further, in addition to the carbonaceous material, a compound including a metallic compound capable of alloying with lithium or a metallic compound and a carbonaceous material may be used as the negative electrode active material.

At least one of Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys and Al alloys may be used as the metal capable of being alloyed with lithium. Further, a metal lithium thin film may be used as the negative electrode active material.

As the negative electrode active material, any one selected from the group consisting of crystalline carbon, amorphous carbon, carbon composite, lithium metal, lithium-containing alloy, and mixtures thereof may be used in view of high stability.

On the other hand, since the electrolytic solution is the same as described above in the section related to the electrolytic solution, its description will be omitted. Since the lithium secondary battery can be manufactured by a conventional method, a detailed description thereof will be omitted herein. Although the pouch type lithium secondary battery is described as an example in the present embodiment, the present invention is not limited to the pouch type lithium secondary battery, and any shape can be used as long as it can operate as a battery.

As described above, the lithium secondary battery including the electrolyte according to the embodiment of the present invention can exhibit the low temperature charging / discharging characteristics and the room temperature recovery rate, and can be used as portable devices such as cellular phones, notebook computers, digital cameras, camcorders, A hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (HEV, PHEV), and a medium to large-sized energy storage system.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Production Example 1. Preparation of electrolytic solution

A mixed solvent in which 1.15 M LiPF ₆ as a lithium salt, ethylene carbonate (EC), ethylmethylcarbonate (EMC) and diethyl carbonate (DEC) as an organic solvent were mixed at a ratio of 3: 4: 3 and an electrolyte additive An electrolyte solution for a lithium secondary battery was prepared using 0.5 weight% of methyl 3-sulfolene-3-carboxylate based on the total weight of the electrolyte solution.

Example 1 and Comparative Example 1. Preparation of lithium secondary battery

The same procedure as in Preparation Example 1 was carried out except that each component was used in the amounts shown in Table 1 below to prepare an electrolyte solution for a lithium secondary battery, and a lithium secondary battery was prepared therefrom.

In detail, the lithium _secondary battery is composed of a cathode, a cathode, a separator, and an electrolytic solution. The cathode contains 85 wt% of lithium cobalt oxide (LiCoO ₂ ) as an active material, 7.5 wt% of polyvinylidene fluoride as a binder, A composition for forming a cathode active material layer containing 7.5% by weight of Super-P carbon was coated on an aluminum foil as a current collector, followed by drying. The negative electrode was further coated with a composition for forming an anode active material layer, which contained 88 weight% of artificial graphite as an active material, 4 weight% of super-P carbon as a conductive material, and 8 weight% of polyvinylidene fluoride as a binder as a current collector on a copper foil Followed by drying. The separator was placed on the positive electrode prepared above, and the carbon negative electrode was placed thereon. Then, the electrolyte solution prepared in the above was injected and vacuum packed with an aluminum pouch to obtain lithium secondary batteries E1 and E2 of Comparative Example 1 and Example 1 ).

Battery number Lithium salt
(M) Organic solvent
(Mixing volume ratio) Electrolyte additive
(weight%) Other additives
(weight%) Comparative Example 1
(E1) LiPF ₆
(One) EC / EMC / DEC
(25:45:30) Bisoxalato borate
(lithium bisoxalato borate (LiBOB)) (1) FEC (1) + LiBF ₄ (0.2) Example 1
(E2) LiPF ₆
(One) EC / EMC / DEC
(25:45:30) Methyl 3-sulfolene-3-carboxylate (0.5) FEC (1) + LiBF ₄ (0.2)

In Table 1 above, FEC is fluoroethylene carbonate.

Test Example 1. Evaluation of charge / discharge characteristics at low temperature

The lithium secondary batteries of Example 1 and Comparative Example 1 prepared above were charged at 0.2 C rate to 4.2 V under constant current (CC) / constant current (CV) conditions at -10 ° C, V (0.2C rate). The same measurement was repeated twice.

Charge and discharge profiles of each lithium secondary battery were observed, and the results are shown in Fig. E1-1 and E1-2 in FIG. 2 show the results of the first and second experiments on the lithium secondary battery of Comparative Example 1, and E2-1 and E2-2 show the results of the first and second experiments on the lithium secondary battery of Example 1, The results of the second experiment are shown.

As shown in Fig. 2, when the charge / discharge characteristics evaluation test at low temperature was performed twice in the same manner, the lithium secondary batteries (E2-1 and E2-2) of Example 1 were tested twice And exhibited a higher discharge capacity and capacity retention ratio than the secondary batteries (E1-1, E1-2).

Test Example 2. Evaluation of Room Temperature Recovery Rate

The lithium rechargeable battery of Example 1 and Comparative Example 1 was subjected to the same charge and discharge tests as in the charging and discharging characteristic evaluation at low temperature in Test Example 1 while varying the temperature at room temperature (25 占 폚), -10 占 폚 and room temperature (25 占 폚) / Charge / discharge was performed under the discharge condition to observe a change in capacity, and the room temperature recovery rate was evaluated from this. The same procedure was repeated twice, and the results are shown in Table 2 and FIG.

Frequency Before the low temperature test
Discharge capacity
(mAh) After the low temperature test
Recovery discharge capacity
(mAh) Room temperature recovery rate
(%) Average room temperature recovery rate
(%) Comparative Example 1 1 time
(E1-1) 1029.64 949.14 92.18 91.73 Episode 2
(E1-2) 1018.48 929.66 91.28 Example 1 1 time
(E2-1) 1021.85 975.08 95.42 95.08 Episode 2
(E2-2) 1034.04 979.61 94.74

As shown in Table 2 and FIG. 3, the lithium secondary batteries (E2-1 and E2-2) of Example 1 including the electrolytic solution according to the present invention are the lithium secondary batteries (E1- 1, and E1-2), which was improved by about 4% or more.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

1: Lithium secondary battery
3: cathode 5: anode
7: separator 9: electrode assembly
10, 13: lead member 15: case

Claims (11)

An electrolyte solution comprising a sulfanecarboxylic acid ester derivative as an electrolyte additive. The method according to claim 1,
Wherein the sulfanecarboxylic acid ester derivative is a compound having a structure represented by the following formula (1).
[Chemical Formula 1]

(Wherein R is selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an acetate group, a (meth) acrylate group, ) The method according to claim 1,
Wherein the sulfanecarboxylic acid ester derivative is methyl 3-sulfolene carboxylate. The method according to claim 1,
Wherein the sulfanecarboxylic acid ester derivative is contained in an amount of 0.1 to 10% by weight based on the total weight of the electrolytic solution. The method according to claim 1,
Wherein the electrolytic solution further comprises an organic solvent and a lithium salt. 6. The method of claim 5,
Wherein the organic solvent is selected from the group consisting of an ester solvent, an ether solvent, a ketone solvent, an aromatic hydrocarbon solvent, an alkoxyalkane solvent, a carbonate solvent, and mixtures thereof. The method according to claim 6,
Wherein the organic solvent comprises an organic solvent having a high dielectric constant and a low viscosity organic solvent in a volume ratio of 2: 8 to 8: 2. 8. The method of claim 7,
The high-k organic solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, and mixtures thereof,
Wherein the low-viscosity organic solvent is selected from the group consisting of methylethylcarbonate, dimethylcarbonate, diethylcarbonate, and mixtures thereof. The method according to claim 6,
The organic solvent may be one obtained by mixing one organic solvent among ethylene carbonate and propylene carbonate: ethyl methyl carbonate: dimethyl carbonate and diethyl carbonate in a volume ratio of 5: 1: 1 to 2: 5: 3 In electrolyte. The method according to claim 6,
The lithium salt is _{LiPF 6, LiClO 4, LiAsF 6} , LiBF 4, LiSbF 6, LiAl0 4, LiAlCl 4, LiCF 3 SO 3, LiC 4 F 9 SO 3, LiN (C 2 F 5 SO 3) 2, LiN ( C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ . _{LiN (C a F 2a + 1} SO 2) (C b F 2b + 1 SO 2) ( a stage, a and b are natural numbers, and 1 = a = 20, 1 = b = 20 Im), LiCl, LiI, LiB (C ₂ O ₄ ) _2, and mixtures thereof. An anode including a cathode active material,
A negative electrode disposed opposite to the positive electrode and including a negative electrode active material, and
And an electrolyte solution interposed between the anode and the cathode,
Wherein the electrolyte solution contains a sulfanecarboxylic acid ester derivative as an electrolyte additive.

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