KR101495295B1 - Nonaqueous electrolyte and lithium secondary battery containing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte and a lithium secondary battery having the same. More particularly, the present invention relates to a specific acrylate compound; Cyclic siloxane-based compounds; Organic solvent; And an electrolyte salt, and a lithium secondary battery having the same.
The non-aqueous electrolyte according to the present invention includes both an acrylate-based compound and a cyclic siloxane-based compound, and when applied to a lithium secondary battery, the long-term performance of the battery is improved by forming a film having excellent electrical conductivity at the time of operating the battery Effect.

Description

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte and a lithium secondary battery having the non-aqueous electrolyte,

The present invention relates to a non-aqueous electrolyte and a lithium secondary battery having the non-aqueous electrolyte, and more particularly, to a non-aqueous electrolyte and a lithium-containing non-aqueous electrolyte having the same, which improves the long- The present invention relates to a secondary battery.

Recently, interest in energy storage technology is increasing. As the application fields of cell phones, camcorders, notebook PCs and even electric vehicles are expanding, efforts for research and development of electrochemical devices are becoming more and more specified. The electrochemical device is one of the most attracting fields in this respect. Of these, the development of a rechargeable secondary battery has become a focus of attention. In recent years, in order to improve the capacity density and the specific energy, Research and development on the design of electrodes and batteries are underway.

Among the currently applied secondary batteries, the lithium secondary battery developed in the early 1990s has advantages such as higher operating voltage and higher energy density than conventional batteries such as Ni-MH, Ni-Cd and sulfuric acid-lead batteries using an aqueous electrolyte solution .

During the initial charging of the lithium secondary battery, lithium ions from the cathode active material such as lithium metal oxide migrate to the anode active material such as graphite and are inserted between the layers of the anode active material. At this time, the electrolyte and the lithium ion react with each other on the surface of the anode active material to form a SEI (Solid Electrolyte Interface) layer. Among the SEI components, it is known that the main components are Li ₂ CO ₃ , Li ₂ O, LiOH, lithium alkoxide, lithium alkyl carbonate and the like.

The SEI layer acts as an ion tunnel to pass only lithium ions. The SEI layer is an effect of such an ion tunnel and prevents an organic solvent molecule having a large molecular weight moving together with lithium ions from being inserted between the layers of the anode active material in the electrolyte solution to destroy the anode structure. Therefore, by preventing contact between the electrolyte solution and the anode active material, decomposition of the electrolyte solution does not occur, and the amount of lithium ions in the electrolyte solution is reversibly maintained, so that stable charge / discharge is maintained.

However, the lithium secondary battery repeatedly shrinks and expands as the charge and discharge proceeds, causing a change in the carbon lattice constant, and the SEI layer is repeatedly broken and restored, resulting in a decrease in capacity. Therefore, in order to solve such a problem, it is still required to develop various compositions of the solvent component of the carbonate organic solvent or to change the shape of the SEI layer forming reaction by mixing specific additives.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for producing a battery, which comprises an acrylate-based compound and a cyclic siloxane-based compound that improve the long-term performance of a battery by forming an excellent film having high ion conductivity and low electronic conductivity on the electrode constituting the battery A non-aqueous electrolyte and a lithium secondary battery having the same.

According to one aspect of the present invention, there is provided an acrylate-based compound represented by Formula 1 below: Cyclic siloxane-based compounds; Organic solvent; And an electrolyte salt.

[Chemical Formula 1]

,

,

,

,

,

,

,

,

,

,

또는

이고, 여기에서 E¹ 내지 E⁴는 각각 독립적으로 수소, C₁~C₁₂의 알킬기, C₆~C₂₀의 아릴기 또는 C₁~C₁₂의 히드록시알킬기이고, m은 0~30 사이의 정수이며, A, X 및 E¹ 내지 E⁴의 1 이상의 수소는 할로겐으로 치환될 수 있다.In Formula 1, A is a C ₁ to C ₁₂ alkylene group; a is an integer from 0 to 30; B is H or a methyl group; b is an integer from 1 to 6; X is a C ₁ to C ₁₂ alkyl group, a C ₆ to C ₂₀ aryl group,

,

,

,

,

,

,

,

,

,

,

or

Wherein each of E ¹ to E ⁴ is independently hydrogen, a C ₁ to C ₁₂ alkyl group, a C ₆ to C ₂₀ aryl group or a C ₁ to C ₁₂ hydroxyalkyl group, and m is an integer of 0 to 30 And at least one hydrogen of A, X and E ¹ to E ⁴ may be substituted with halogen.

The acrylate compound may be at least one selected from the group consisting of tetraethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (1,6-hexanediol diacrylate, -hexanediol diacrylate, trimethylol propane ethoxylate triacrylate, trimethylol propane propoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate ), Trimethylolpropane triacrylate (TMPTA), di (trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate (dipentaerythritol pentaacrylate) and dipentaerythritol Four acrylate may be any one or a mixture of two or more of those selected from the group consisting of (dipentaerythritol hexaacrylate).

The cyclic siloxane-based compound may be at least one selected from the group consisting of tetramethyl cyclotetrasiloxane, hexamethyl cyclotrisiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, Dodecamethyl cyclohexasiloxane, or a mixture of two or more thereof.

The organic solvent may be at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), diethyl carbonate (DEC), dimethyl carbonate EMC), methyl formate (MF), gamma-butyrolactone (γ-BL), sulfolane, methyl acetate (MA), methyl propionate (MP) Ethyl propionate (EP), or a mixture of two or more thereof.

Further, the electrolyte salt, as ^{anions, 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 5) 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 ^- , or two or more of them.

The acrylate-based compound may be contained in the non-aqueous electrolyte in an amount of 0.1 to 3 wt%, and the cyclic siloxane-based compound may be included in the non-aqueous electrolyte in an amount of 0.1 to 3 wt%.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising an anode, a cathode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte of the present invention.

The anode may include an anode active material layer containing a lithium metal, a carbon material, a metal compound, or a mixture thereof.

The metal compound is composed of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Or a compound containing two or more of these metal elements, or a mixture thereof.

On the other hand, the cathode may include a cathode active material layer containing a lithium-containing oxide, and the lithium-containing oxide may be a lithium-containing transition metal oxide.

The lithium-containing transition metal oxide may be at least one selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ <1, a + b + c = 1), LiNi 1 - y Co y O 2, LiCo 1 - y Mn y O 2, LiNi 1 -y Mn y O 2 (O≤y <1), Li (Ni a _{Co b Mn c) O 4 (} 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn 2 - z Ni z O 4, LiMn 2 -z Co z O ₄ (0 <z <2), LiCoPO ₄ and LiFePO ₄ , or a mixture of two or more thereof.

The non-aqueous electrolyte according to the present invention includes both an acrylate-based compound and a cyclic siloxane-based compound, and when applied to a lithium secondary battery, an excellent coating having high ion conductivity and low electronic conductivity at the time of operation of the battery is formed on the electrode, Term effect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing a comparison of capacitive changes due to charging and discharging of lithium secondary batteries manufactured according to Examples and Comparative Examples of the present invention. FIG.

Hereinafter, the present invention will be described in detail with reference to the drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

In addition, since the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention, It is to be understood that equivalents and modifications are possible.

According to one aspect of the present invention, there is provided an acrylate-based compound represented by Formula 1 below; Cyclic siloxane-based compounds; Organic solvent; And an electrolyte salt.

[Chemical Formula 1]

,

,

,

,

,

,

,

,

,

,

또는

이고, 여기에서 E¹ 내지 E⁴는 각각 독립적으로 수소, C₁~C₁₂의 알킬기, C₆~C₂₀의 아릴기 또는 C₁~C₁₂의 히드록시알킬기이고, m은 0~30 사이의 정수이며, A, X 및 E¹ 내지 E⁴의 1 이상의 수소는 할로겐으로 치환될 수 있다.In Formula 1, A is a C ₁ to C ₁₂ alkylene group; a is an integer from 0 to 30; B is H or a methyl group; b is an integer from 1 to 6; X is a C ₁ to C ₁₂ alkyl group, a C ₆ to C ₂₀ aryl group,

,

,

,

,

,

,

,

,

,

,

or

Wherein each of E ¹ to E ⁴ is independently hydrogen, a C ₁ to C ₁₂ alkyl group, a C ₆ to C ₂₀ aryl group or a C ₁ to C ₁₂ hydroxyalkyl group, and m is an integer of 0 to 30 And at least one hydrogen of A, X and E ¹ to E ⁴ may be substituted with halogen.

The acrylate compound may be at least one selected from the group consisting of tetraethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (1,6-hexanediol diacrylate, -hexanediol diacrylate, trimethylol propane ethoxylate triacrylate, trimethylol propane propoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate ), Trimethylolpropane triacrylate (TMPTA), di (trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate (dipentaerythritol pentaacrylate) and dipentaerythritol Four acrylate can be any one or a mixture of two or more of those selected from the group consisting of (dipentaerythritol hexaacrylate), but is not limited thereto.

The cyclic siloxane-based compound contained in the non-aqueous electrolyte of the present invention may be at least one selected from the group consisting of tetramethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, Decamethylcyclopentasiloxane, and dodecamethyl cyclohexasiloxane, or a mixture of two or more thereof, but the present invention is not limited thereto.

The organic solvent may be any of those conventionally used for an electrolyte for a lithium secondary battery. For example, ether, ester, amide, linear carbonate, and cyclic carbonate may be used alone or in combination of two or more. have.

Among them, a carbonate compound which is typically a cyclic carbonate, a linear carbonate, or a mixture thereof may be included.

Specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, Propylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and halides thereof, or a mixture of two or more thereof. Examples of such halides include, but are not limited to, fluoroethylene carbonate (FEC) and the like.

Specific examples of the linear carbonate compound include any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate and ethyl propyl carbonate And mixtures of two or more of them may be used as typical examples, but the present invention is not limited thereto.

As the ether in the organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether and ethyl propyl ether or a mixture of two or more thereof may be used , But is not limited thereto.

Examples of the ester in the organic solvent include methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate,? -Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolactone and? -Caprolactone, or a mixture of two or more thereof, but the present invention is not limited thereto.

The electrolyte salt included in the non-aqueous electrolyte according to an embodiment of the present invention may be an electrolyte solution containing an anion 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 5}} ) 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 ^- . Examples of the electrolyte salt include LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, and lower aliphatic carboxylic acid lithium, but are not limited thereto.

In the non-aqueous electrolyte of the present invention, the acrylate-based compound may be contained in the non-aqueous electrolyte in an amount of 0.1 to 3 wt%, and the cyclic siloxane-based compound may be contained in the non-aqueous electrolyte in an amount of 0.1 to 3 wt% . If the content of the acrylate-based compound and the cyclic siloxane-based compound in the non-aqueous electrolyte is less than 0.1% by weight, the effect of forming an excellent film having a high ionic conductivity and a low electronic conductivity is insignificant. If the content is more than 3% by weight, The performance of the battery may be deteriorated.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising an anode, a cathode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte of the present invention.

The lithium secondary battery according to the present invention can be produced by a conventional method known in the art. For example, a porous separator may be inserted between the cathode and the anode, and the nonaqueous electrolyte solution according to the present invention may be added to the separator.

The separator used in one embodiment of the present invention may be any porous substrate commonly used in the art, and may be, for example, a polyolefin porous membrane or a nonwoven fabric, but is not particularly limited thereto .

Examples of the polyolefin-based porous film include polyolefin-based polymers such as polyethylene, polypropylene, polybutylene, and polypentene, such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene and ultra-high molecular weight polyethylene, One membrane can be mentioned.

The nonwoven fabric may include, in addition to the polyolefin nonwoven fabric, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate ), Polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylenesulfide, and polyethylene naphthalene, which may be used alone or in combination, And nonwoven fabrics formed by mixing these polymers. The structure of the nonwoven fabric may be a spun bond nonwoven fabric or a meltblown nonwoven fabric composed of long fibers.

The thickness of the porous substrate is not particularly limited, but may be 5 to 50 탆, and the pore size and porosity present in the porous substrate are also not particularly limited, but may be 0.01 to 50 탆 and 10 to 95%, respectively.

The anode has a structure in which the anode layer including the anode active material and the binder is supported on one or both surfaces of the current collector.

As the anode active material, a carbon material, a lithium metal, a metal compound, or a mixture thereof, in which lithium ions can be occluded and released, may be used.

Concretely, as the carbon material, low-crystallinity carbon and high-crystallinity carbon may be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes.

The metal compound may be at least one selected from the group consisting of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, And compounds containing at least one metal element. These metal compounds may be a single substance, an alloy, an oxide (TiO ₂ , SnO ₂ Or the like), a nitride, a sulfide, a boride, an alloy with lithium, or the like, but an alloy with a single substance, an alloy, an oxide, and lithium can be increased in capacity. Among them, it may contain at least one element selected from Si, Ge and Sn, and it may further increase the capacity of the battery including at least one element selected from Si and Sn.

The cathode has a structure in which a cathode layer including a cathode active material, a conductive material and a binder is supported on one or both surfaces of the current collector.

As the cathode active material, a lithium-containing transition metal oxide may be preferably used. For example, Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _x MnO ₂ <x <1.3, 0 <a <1, 0 <b <1), Li _x Mn ₂ O ₄ (0.5 <x <1.3), Li _x (Ni _a Co _b Mn _c ) O ₂ , 0 <c <1, a + b + c = 1), Li x Ni 1-y Co y O 2 (0.5 <x <1.3, 0 <y <1), Li x Co 1 -y Mn y O 2 (0.5 <x <1.3, 0≤y <1), Li x Ni 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3, 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _z O ₄ , 0 <z <2), Li x Mn 2 -z Co z O 4 (0.5 <x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3) and Li _x FePO ₄ (0.5 < x < 1.3), or a mixture of two or more thereof. The lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may also be used.

The conductive material is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in an electrochemical device. In general, carbon black, graphite, carbon fiber, carbon nanotube, metal powder, conductive metal oxide, organic conductive material and the like can be used. Commercially available products as the conductive material include acetylene black series (manufactured by Chevron Chemical Co., (Chevron Chemical Company or Gulf Oil Company products), Ketjen Black EC series (Armak Company), Vulcan XC-72 (Cabot Company) and Super P (MM (MMM)). For example, acetylene black, carbon black and graphite.

The binder used for the cathode and the anode has a function of holding the cathode active material and the anode active material in the current collector and also connecting the active materials, and a commonly used binder may be used without limitation.

For example, it is possible to use vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, styrene Various types of binder polymers such as styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and the like can be used.

The current collector used for the cathode and the anode may be any metal having a high conductivity and a metal which can easily adhere to the slurry of the active material and is not reactive in the voltage range of the battery. Specifically, examples of the current collector for a cathode include aluminum, nickel, or a combination thereof. Examples of the current collector for an anode include copper, gold, nickel, or a copper alloy or a combination thereof And the like. In addition, the current collector may be used by laminating the substrates made of the above materials.

The cathode and the anode are kneaded using an active material, a conductive material, a binder and a high boiling point solvent to prepare an electrode mixture, and then the mixture is coated on a copper foil or the like of the current collector, dried, Followed by heat treatment at a temperature of about 250 DEG C for about 2 hours under vacuum.

The thickness of the active material layer of the cathode may be 30 to 120 占 퐉 or 50 to 100 占 퐉, and the thickness of the active material layer of the anode may be 1 to 100 占 퐉 or 3 to 70 占 퐉. have. When the cathode and the anode satisfy this thickness range, the amount of active material in each electrode active material layer is sufficiently secured, the battery capacity can be prevented from being reduced, and the cycle characteristics and rate characteristics 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 should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example  One

(1) Preparation of non-aqueous electrolyte

A mixed solvent was prepared in a weight ratio of ethylene carbonate (EC): ethyl propionate (EP): diethyl carbonate (DEC) = 3: 4: 3 and then di (trimethylolpropane) ) tetraacrylate) and 2,4,6,8-tetramethylcyclotetrasiloxane are added to the solvent to prepare a solution. Here, the di (trimethylolpropane) tetraacrylate and the 2,4,6,8-tetramethylcyclotetrasiloxane are each prepared so as to contain 0.5% by weight in the prepared solution. Then, LiPF ₆ as a lithium salt was added to the solution so as to be 1 M to prepare a nonaqueous electrolyte solution.

(2) Manufacture of cathode

LiCoO ₂ cathode active material was prepared. Thereafter, a slurry was prepared by mixing the cathode active material: conductive material: binder in a weight ratio of 96: 2: 2, coating the aluminum (Al) foil current collector by a conventional method, and drying to prepare a cathode.

(3) Manufacture of anode

An anode active material slurry was prepared by mixing artificial graphite: SBR binder: thickener in a weight ratio of 98: 1: 1, and then coated on a copper (Cu) foil current collector by a conventional method to prepare an anode.

(4) Production of lithium secondary battery

A jelly roll made by interposing a polyethylene porous film between the cathode and the anode was fabricated into a conventional prismatic battery, and the prepared nonaqueous electrolyte was injected to prepare a lithium secondary battery.

Comparative Example  One

A lithium secondary battery was produced in the same manner as in Example 1, except that in the preparation of the nonaqueous electrolyte (1) of Example 1, 2,4,6,8-tetramethylcyclotetrasiloxane was not included.

Comparative Example  2

A lithium secondary battery was produced in the same manner as in Example 1 except that di (trimethylolpropane) tetraacrylate was not included in the preparation of the nonaqueous electrolyte (1) of Example 1.

Comparative Example  3

(1) The same procedure as in Example 1 was carried out except that 2,4,6,8-tetramethylcyclotetrasiloxane and di (trimethylolpropane) tetraacrylate were not included in the preparation of the non-aqueous electrolyte of Example 1 To prepare a lithium secondary battery.

Evaluation of Initial Capacity of Lithium Secondary Battery

The prepared lithium secondary batteries of Example 1 and Comparative Examples 1 to 3 were subjected to a constant current / constant voltage condition and a 0.05 C cut-off charge (overcharge protection function) at 0.3 C rate. Then, a constant-current / constant-voltage charging was performed at a rate of 1 C, and the capacity was measured by discharging at a constant current of 0.2 C. The results are shown in Table 1 below.

0.2C capacity (mAh) Example 1 833 Comparative Example 1 822 Comparative Example 2 822 Comparative Example 3 827

As shown in Table 1, di (trimethylolpropane) tetraacrylate (di (trimethylolpropane) tetraacrylate) and 2,4,6,8-tetramethylcyclotetrasiloxane (2,4,6,8-tetramethyl cyclotetrasiloxane) containing only di (trimethylol propane) tetraacrylate (2,4,6,8-tetramethylcyclotetrasiloxane (2, 3, 4, 4,6,8-tetramethyl cyclotetrasiloxane) was included, or the initial dose was higher than that when both were not included.

Evaluation of long-term performance of lithium secondary battery

Charging and discharging capacity retention characteristics tests were performed through charging the lithium secondary batteries of Example 1 and Comparative Examples 1 to 3 at a constant current / constant voltage of 1 C rate and discharging at a constant current of 1 C, Respectively.

As can be seen from FIG. 1, as a result of carrying out 250 charge and discharge cycles, di (trimethylolpropane) tetraacrylate (di (trimethylolpropane) tetraacrylate) and 2,4,6,8-tetramethylcyclotetrasiloxane , 6,8-tetramethyl cyclo tetra siloxane) was found to be the lowest in the lithium secondary battery.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (13)

An acrylate-based compound represented by the following formula (1);
Cyclic siloxane-based compounds;
Organic solvent; And
An electrolyte salt,
The cyclic siloxane-based compound may be at least one selected from the group consisting of tetramethyl cyclotetrasiloxane, hexamethyl cyclotrisiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, A dodecamethyl cyclohexasiloxane, or a mixture of two or more thereof.
[Chemical Formula 1]

In Formula 1, A is a C ₁ to C ₁₂ alkylene group; a is an integer from 0 to 30; B is H or a methyl group; b is an integer from 1 to 6;
X is a C ₁ to C ₁₂ alkyl group, a C ₆ to C ₂₀ aryl group,

,

,

,

,

,

,

,

,

,

,

or

Wherein each of E ¹ to E ⁴ is independently hydrogen, a C ₁ to C ₁₂ alkyl group, a C ₆ to C ₂₀ aryl group or a C ₁ to C ₁₂ hydroxyalkyl group, and m is an integer of 0 to 30 And at least one hydrogen of A, X and E ¹ to E ⁴ may be substituted with halogen. The method according to claim 1,
The acrylate compound may be selected from the group consisting of tetraethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6- hexanediol diacrylate, trimethylol propane ethoxylate triacrylate, trimethylol propane propoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate, , Trimethylolpropane triacrylate (TMPTA), di (trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate ( dipentaerythritol pentaacrylate) and dipentaerythritol hexaac Dipentaerythritol hexaacrylate, or a mixture of two or more thereof. delete The method according to claim 1,
Examples of the organic solvent include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, (DEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate A solvent such as methanol, ethanol, propanol, isopropanol, isopropanol, butanol, isopropanol, butanol, isopropanol, Pyronate,? -Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolactone and? -Caprolactone The non-aqueous electrolyte, characterized in that any one or a mixture of two or more of those selected from the group true luer. The method according to claim 1,
The electrolyte salt includes, as ^{anions, 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 5) 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 ^- , or two or more of them. The method according to claim 1,
Wherein the acrylate-based compound is contained in an amount of 0.1 to 3% by weight in the non-aqueous electrolyte. The method according to claim 1,
Wherein the cyclic siloxane-based compound is contained in an amount of 0.1 to 3% by weight in the non-aqueous electrolyte. A lithium secondary battery comprising an anode, a cathode, and a non-aqueous electrolyte,
The nonaqueous electrolyte according to any one of claims 1, 2, and 4 to 7, wherein the nonaqueous electrolyte is a nonaqueous electrolyte. 9. The method of claim 8,
Wherein the anode comprises an anode active material layer comprising a lithium metal, a carbon material, a metal compound, or a mixture thereof. 10. The method of claim 9,
Wherein the metal compound is selected from the group consisting of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, A compound containing any one or two or more metal elements selected from the above, or a mixture thereof. 9. The method of claim 8,
Wherein the cathode comprises a cathode active material layer containing a lithium-containing oxide. 12. The method of claim 11,
Wherein the lithium-containing oxide is a lithium-containing transition metal oxide. 13. The method of claim 12,
Wherein the lithium-containing transition metal oxide is at least one selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b < , a + b + c = 1 ), LiNi 1 - y Co y O 2, LiCo 1 - y Mn y O 2, LiNi 1 -y Mn y O 2 (O≤y <1), Li (Ni a Co b _{Mn c) O 4 (0 <} a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn 2 - z Ni z O 4, LiMn 2 -z Co z O 4 (0 <z <2), LiCoPO 4 , and any one or a lithium secondary battery, characterized in that a mixture of two or more of those selected from the group consisting of LiFePO _4.

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