KR20130134744A - Nonaqueous electrolyte and lithium secondary battery using the same - Google Patents

Abstract

The present invention relates to non-aqueous electrolyte and a lithium secondary battery using the same, and, more specifically, to non-aqueous electrolyte comprising an acrylate compound having a specific structure, adiponitrile (ADN), an ester compound, an organic solvent and an electrolyte salt; and a lithium secondary battery using the same. When the non-aqueous electrolyte according to the present invention is applied to a lithium secondary battery, the effect of improving the life performance of the battery is exhibited by forming a stable coating film on the electrode in charge/discharge of the battery. [Reference numerals] (AA) Example;(BB) Comparative example 1;(CC) Comparative example 2;(DD) Comparative example 3;(EE) Comparative example 4;(FF) Comparative example 5

Description

Non-aqueous electrolyte and lithium secondary battery using the same {Nonaqueous electrolyte and lithium secondary battery using the same}

The present invention relates to a nonaqueous electrolyte and a lithium secondary battery using the same, and more particularly, to a nonaqueous electrolyte and a lithium secondary battery using the same to improve the life performance of the 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 the most attention in this regard, the development of a secondary battery capable of charging and discharging has been the focus of attention, and recently in the development of such a battery in order to improve the capacity density and specific energy R & D on the design of electrodes and batteries is 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 . However, such a lithium ion battery has safety problems such as ignition and explosion when using an organic electrolytic solution, and it is disadvantageous in that it is difficult to manufacture. The recent lithium ion polymer battery is considered to be one of the next generation batteries by improving the weak point of the lithium ion battery, but the capacity of the battery is still relatively low as compared with the lithium ion battery.

On the other hand, during the initial charging of the lithium secondary battery, lithium ions derived from cathode active materials such as lithium metal oxides are transferred to anode active materials such as graphite and intercalated between the layers of the anode active materials. At this time, since lithium has a high reactivity, the electrolyte and the carbon constituting the anode active material react on the surface of the anode active material such as graphite to generate compounds such as Li ₂ CO ₃ , Li ₂ O, and LiOH. These compounds form a kind of SEI (Solid Electrolyte Interface) layer on the surface of an anode active material such as graphite.

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 the structure of the anode from being destroyed by inserting an organic solvent molecule having a large molecular weight moving with lithium ions in the electrolyte between the layers of the anode active material. 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 to maintain stable charge and discharge.

However, as lithium secondary batteries are continuously charged and discharged, the carbon material is detached from the electron transfer passage due to the change in the carbon lattice constant and the gas generation due to the decomposition of the solvent, thereby decreasing its capacity. Therefore, in order to solve such a problem, development of a method for improving the life of a battery is continuously required.

The problem to be solved by the present invention is to provide a non-aqueous electrolyte lithium secondary battery and a lithium secondary battery using the same to improve the life performance of the battery by forming a stable film on the electrode constituting the battery.

In order to solve the above problems, according to an aspect of the present invention, an acrylate compound represented by the following formula (1); Adiponitrile (ADN); Ester compounds; Organic solvent; And a nonaqueous electrolyte comprising an electrolyte salt.

[Formula 1]

,

,

,

,

,

,

,

,

,

,

또는

이고, 여기에서 E¹ 내지 E⁴는 각각 독립적으로 수소, C₁~C₁₂의 알킬기, C₁~C₁₂의 할로알킬기 또는 C₁~C₁₂의 히드록시알킬기이고, m은 0~30 사이의 정수이다.In Formula 1, A is C ₁ ~ C ₁₂ alkylene or C ₁ ~ C ₁₂ haloalkylene; a is an integer between 0 and 30; B is H or a methyl group; b is an integer between 2 and 6; X is

,

,

,

,

,

,

,

,

,

,

or

And, where E ¹ to E ⁴ is a hydroxyalkyl group each independently hydrogen, C ₁ ~ C ₁₂ alkyl group, C ₁ ~ C ₁₂ haloalkyl group or a C ₁ ~ C ₁₂ of a, m is from 0 to 30 Is an integer.

Here, the organic solvent may be ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2, 3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methyl May be any one selected from the group consisting of propyl carbonate, ethylpropyl carbonate, dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, ethylpropyl ether and sulfolane or mixtures of two or more thereof have.

In addition, the acrylate compound, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, bisphenol A ethoxylated diacrylate, 1, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylol propane ethoxylate triacrylate, trimethyl Trimethylol propane propoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate, trimethylolpropane triacrylate (TMPTA), tris [2- (acrylo) Yloxy) ethyl] isocyanurate (tris [2- (acryloyloxy) ethyl] isocyanurate), di ( Trimethylolpropane) tetraacrylate (di (trimethylolpropane) tetraacrylate), pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (dipentaerythritol hexaacrylate) It may be any one selected from the group consisting of or a mixture of two or more thereof.

In addition, the ester compound may be represented by the following Chemical Formula 2.

(2)

In Formula 2, R ₁ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and R ₂ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

And, the ester compound is methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-capro Lactone, s-valerolactone and ε-caprolactone, or any one selected from the group consisting of two or more thereof.

In addition, the electrolyte salt ^{anion, 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 ^-It may be any one selected from the group consisting of or two or more thereof.

In addition, the acrylate compound and the adiponitrile may be included in the non-aqueous electrolyte solution independently of each other in 0.5 to 10% by weight, and the ester compound may be included in the non-aqueous electrolyte solution in 30 to 90% by weight.

Meanwhile, according to another aspect of the present invention, there is provided a lithium secondary battery including an anode, a cathode, and a nonaqueous electrolyte, wherein the nonaqueous electrolyte is a nonaqueous electrolyte according to the present invention.

In this case, the anode may be provided with an anode active material layer containing a lithium metal, a carbon material, a metal compound or a mixture thereof.

Here, the metal compound is Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Mg, Sr, and Ba It may be any one selected from the group consisting of, or a compound containing two or more metal elements thereof, or a mixture thereof.

The cathode may include a cathode active material layer containing a lithium-containing oxide.

The lithium-containing oxide may be a lithium-containing transition metal oxide, and the lithium-containing transition metal oxide may be LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , or Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b <1, 0 <c <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 -} may be the _{z Ni z O 4, LiMn 2} -z Co z O 4 (0 <z <2), LiCoPO 4 , and any one or a mixture of two or more of those selected from the group consisting of LiFePO _4.

Application of the nonaqueous electrolyte according to the present invention to a lithium secondary battery has an effect of improving the life performance of the battery by forming a stable film on the electrode during charging and discharging of the battery.

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.
1 is a graph showing a comparison of capacity changes according to charge and discharge of a lithium secondary battery manufactured according to Examples and Comparative Examples of the present invention.

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.

Non-aqueous electrolyte according to an embodiment of the present invention, the acrylate compound represented by the formula (1); Adiponitrile (ADN); Ester compounds; Organic solvent; And electrolyte salts.

[Formula 1]

,

,

,

,

,

,

,

,

,

,

또는

이고, 여기에서 E¹ 내지 E⁴는 각각 독립적으로 수소, C₁~C₁₂의 알킬기, C₁~C₁₂의 할로알킬기 또는 C₁~C₁₂의 히드록시알킬기이고, m은 0~30 사이의 정수이다.In Formula 1, A is C ₁ ~ C ₁₂ alkylene or C ₁ ~ C ₁₂ haloalkylene; a is an integer between 0 and 30; B is H or a methyl group; b is an integer between 2 and 6; X is

,

,

,

,

,

,

,

,

,

,

or

And, where E ¹ to E ⁴ is a hydroxyalkyl group each independently hydrogen, C ₁ ~ C ₁₂ alkyl group, C ₁ ~ C ₁₂ haloalkyl group or a C ₁ ~ C ₁₂ of a, m is from 0 to 30 Is an integer.

When the nonaqueous electrolyte is applied to a lithium secondary battery, a stable film is formed on the electrode during charging and discharging of the battery, thereby improving battery life performance.

At this time, the acrylate-based compound, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, bisphenol A ethoxylated diacrylate, 1, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylol propane ethoxylate triacrylate, trimethyl Trimethylol propane propoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate, trimethylolpropane triacrylate (TMPTA), tris [2- (acrylo) Yloxy) ethyl] isocyanurate (tris [2- (acryloyloxy) ethyl] isocyanurate), Dimethylolpropane) tetraacrylate (di (trimethylolpropane) tetraacrylate), pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (dipentaerythritol hexaacrylate) It may be any one selected from the group consisting of or a mixture of two or more thereof, but is not limited thereto.

In addition, the ester compound may be represented by the following Chemical Formula 2.

(2)

In Formula 2, R ₁ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and R ₂ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

And, the ester compound is methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-capro Lactone, s-valerolactone and ε-caprolactone, or any one selected from the group consisting of two or more thereof.

In addition, the electrolyte salt ^{anion, 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 ^-It may be any one selected from the group consisting of or two or more thereof.

Here, non-limiting examples of the electrolyte salt, 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, lower aliphatic lithium carbonate and lithium tetraphenyl borate may be used, but is not limited thereto.

In addition, the electrolyte salt may be included in 10 to 25% by weight in the non-aqueous electrolyte.

On the other hand, the organic solvent can be used without limitation, those conventionally used in the electrolyte for lithium secondary batteries, except for the ester compound, for example, ether, amide, linear carbonate, cyclic carbonate, etc. alone or in combination of two or more Can be used.

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.

In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates in the carbonate-based organic solvent, are high-viscosity organic solvents having a high dielectric constant and can dissociate the lithium salt in the electrolyte more easily. In addition, such cyclic carbonates can be used as dimethyl carbonate and diethyl carbonate When a low viscosity, low dielectric constant linear carbonate is mixed in an appropriate ratio, an electrolyte having a higher electric conductivity can be produced.

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.

The acrylate compound may be included in the nonaqueous electrolyte at 0.5 to 10% by weight, the adiponitrile may be included at 0.5 to 10% by weight in the nonaqueous electrolyte, and the ester compound may be included in the nonaqueous electrolyte. 30 to 90% by weight of the electrolyte may be included.

When the acrylate compound, the adiponitrile, and the ester compound satisfy the above conditions, a stable film may be formed on the electrode, thereby maximizing the effect of improving the life characteristics of the battery.

The coating, for example, a solid electrolyte interface (SEI), may be formed during initial charging or subsequent charge / discharge of the battery.

Meanwhile, a lithium secondary battery according to an embodiment of the present invention includes an anode, a cathode, and a nonaqueous electrolyte according to an embodiment of the present invention.

The lithium secondary battery according to one embodiment of the present invention may be manufactured according to conventional methods 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.

In this case, in the separator of the present invention, any porous substrate used for an electrochemical device may be used as the porous substrate on which the porous coating layer is formed. For example, a polyolefin-based porous membrane or a nonwoven fabric may be used. However, the present invention 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 be, for example, polyethylene terephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, or polycarbonate. ), Polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, polyethylenenaphthalene, etc., alone or separately The nonwoven fabric formed from the polymer which mixed these is mentioned. The structure of the nonwoven fabric may be a spun bond nonwoven fabric or a meltblown nonwoven fabric composed of long fibers.

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

As the anode active material, a carbon material, a lithium metal, a metal compound, or a mixture thereof, which can normally occlude and release lithium ions, 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 active material layer including a cathode active material, a conductive material, and a binder is supported on one or both surfaces of a current collector.

Lithium-containing transition metal oxide may be preferably used as the cathode active material, for example, Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _x MnO ₂ (0.5 <x <1.3), Li _x Mn ₂ O ₄ (0.5 <x <1.3), Li _x (Ni _a Co _b Mn _c ) O ₂ (0.5 <x <1.3, 0 <a <1, 0 <b <1 , 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 (0.5 <x <1.3 , 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), any one selected from the group consisting of, or a mixture of two or more thereof may be used. The lithium-containing transition metal oxide may be coated with a metal or metal oxide such as aluminum (Al). 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 respective active materials, conductive materials, binders, and high boiling point solvents to form an electrode mixture, and then the mixture is applied to a copper foil of a current collector, dried, and press-molded. It can be manufactured by heat-processing under vacuum at about 250 degreeC for 2 hours, respectively.

In addition, the thickness of the active material layer of the cathode (per side of the current collector) may be 30 to 120㎛, or 50 to 100㎛, the thickness of the active material layer of the anode may be 1 to 100㎛, or 3 to 70㎛ 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, and the battery capacity can be prevented from being reduced, and the cycle characteristics and the 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

After preparing a mixed solvent in a weight ratio of ethylene carbonate (EC): propyl propionate (PP) = 3: 7, LiPF ₆ as a lithium salt was added to the solvent to 1M to prepare a solution. Then, vinylene carbonate (VC), adiponitrile (ADN), and trimethylolpropane triacrylate were added to the solution to prepare a nonaqueous electrolyte solution. The vinylene carbonate, adiponitrile and trimethylolpropane triacrylate were included in amounts of 2 parts by weight, 3 parts by weight and 0.5 parts by weight, respectively, based on 100 parts by weight of the solution.

(2) Manufacture of cathode

LiCoO _2: A cathode active material was prepared by mixing in a weight ratio of _{1: LiNi 0 .56 Co 0 .2} Mn 0 .27 O 2 = 2. Thereafter, a cathode active material: conductive material: binder was mixed at a weight ratio of 96: 2: 2 to form a slurry, and then coated on an aluminum (Al) foil current collector in a conventional manner, followed by drying to prepare a cathode.

(3) Manufacture of anode

An artificial 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

Coin cells were prepared in a conventional manner using an electrode assembly prepared by interposing a polyethylene porous membrane between the prepared cathode and anode and the prepared nonaqueous electrolyte.

Comparative Example  One

Example 1 (1) In the preparation of the non-aqueous electrolyte, a lithium secondary battery was manufactured in the same manner as in Example 1 except that succinonitrile (SN) was used instead of adiponnitrile (ADN).

Comparative Example  2

In the preparation of the non-aqueous electrolyte of Example 1 (1), a lithium secondary battery was manufactured in the same manner as in Example 1 except that trimethylolpropane triacrylate was not included.

Comparative Example  3

In the preparation of the non-aqueous electrolyte of Example 1 (1), a lithium secondary battery was manufactured in the same manner as in Example 1 except that adiponitrile was not included.

Comparative Example  4

In preparing (1) the nonaqueous electrolyte of Example 1, diethyl carbonate (DEC) was used instead of propyl propionate, succinonitrile was used instead of adiponitrile, and trimethylolpropane triacrylate was not included. Except for the lithium secondary battery was prepared in the same manner as in Example 1.

Comparative Example  5

Example 1 (1) In the preparation of the non-aqueous electrolyte, a lithium secondary battery was prepared in the same manner as in Example 1 except for using diethyl carbonate (DEC) instead of propyl propionate.

Life performance evaluation of lithium secondary battery

The lithium secondary batteries of Example 1 and Comparative Examples 1 to 5 prepared above were charged and discharged at a constant current 1C rate. While repeating the above charge and discharge 100 times, the battery capacity was measured for each cycle, and is shown in FIG. 1.

And after the charge and discharge of the 100 times for the lithium secondary batteries of Example 1 and Comparative Examples 1 to 5 were prepared, the capacity retention rate of each lithium secondary battery was measured and shown in Table 1 below.

Capacity retention rate (%) Example 1 77.3 Comparative Example 1 60.7 Comparative Example 2 50.6 Comparative Example 3 69.9 Comparative Example 4 37.6 Comparative Example 5 46.1

As can be seen from Table 1, in the case of a lithium secondary battery using an electrolyte solution containing propyl propionate as an ester compound (Example 1 and Comparative Examples 1 to 3), lithium containing an electrolyte solution using diethyl carbonate was used. It can be seen that the capacity retention ratio is higher than that of the secondary batteries (Comparative Examples 4 and 5).

And the capacity retention rate of the lithium secondary battery (Example 1) using the electrolyte containing all of the ester compound propyl propionate, adiponitrile (ADN) and trimethylolpropane triacrylate is the highest (77.3%), the other battery It can be seen that the life performance is higher than that measured.

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 (15)

An acrylate compound represented by Formula 1 below;
Adiponitrile (ADN);
Ester compounds;
Organic solvent; And
Non-aqueous electrolyte containing electrolyte salts:
[Chemical Formula 1]

In Formula 1, A is C ₁ ~ C ₁₂ alkylene or C ₁ ~ C ₁₂ haloalkylene; a is an integer between 0 and 30; B is H or a methyl group; b is an integer between 2 and 6;
X is

,

,

,

,

,

,

,

,

,

,

or

And, where E ¹ to E ⁴ is a hydroxyalkyl group each independently hydrogen, C ₁ ~ C ₁₂ alkyl group, C ₁ ~ C ₁₂ haloalkyl group or a C ₁ ~ C ₁₂ of a, m is from 0 to 30 Is an integer. The method of claim 1,
The organic solvent is ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3 Pentylene carbonate, vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl Carbonate, ethylpropyl carbonate, dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, ethylpropyl ether and sulfolane, or any one or a mixture of two or more thereof Nonaqueous electrolyte solution to be used. The method of claim 1,
The acrylate compound is tetraethylene glycol diacrylate, polyethylene glycol diacrylate, bisphenol A ethoxylated diacrylate, 1,4- 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylol propane ethoxylate triacrylate, trimethylol propane Propoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate, trimethylolpropane triacrylate (TMPTA), tris [2- (acryloyloxy ) Ethyl] isocyanurate (tris [2- (acryloyloxy) ethyl] isocyanurate), di (trime Olpropane) tetraacrylate (di (trimethylolpropane) tetraacrylate), pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate Non-aqueous electrolyte, characterized in that any one selected from the group or a mixture of two or more thereof. The method of claim 1,
The ester compound is a non-aqueous electrolyte, characterized in that represented by the formula (2):
(2)

In Formula 2, R ₁ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and R ₂ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms. The method of claim 1,
The ester compound is methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, Non-aqueous electrolyte, characterized in that any one or a mixture of two or more selected from the group consisting of σ-valerolactone and ε-caprolactone. The method of claim 1,
The electrolyte salt ^{anion, 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 - non-aqueous electrolyte, characterized in that any one or more than two of those selected from the group consisting of. The method of claim 1,
The acrylate compound is a non-aqueous electrolyte, characterized in that contained in 0.5 to 10% by weight in the non-aqueous electrolyte. The method of claim 1,
The adiponitrile (adiponitrile; ADN) is a non-aqueous electrolyte, characterized in that contained in 0.5 to 10% by weight in the non-aqueous electrolyte. The method of claim 1,
The ester compound is a non-aqueous electrolyte, characterized in that contained in 30 to 90% by weight in the non-aqueous electrolyte. A lithium secondary battery comprising an anode, a cathode and a nonaqueous electrolyte,
The nonaqueous electrolyte is a nonaqueous electrolyte of any one of claims 1 to 9, characterized in that the lithium secondary battery. The method of claim 10,
Wherein the anode comprises an anode active material layer comprising a lithium metal, a carbon material, a metal compound, or a mixture thereof. 12. The method of claim 11,
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, Or a compound containing two or more of these metal elements, or a mixture thereof. The method of claim 10,
Wherein the cathode comprises a cathode active material layer containing a lithium-containing oxide. The method of claim 13,
Wherein the lithium-containing oxide is a lithium-containing transition metal oxide. 15. The method of claim 14,
The lithium-containing transition metal oxide is Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _x MnO ₂ (0.5 <x <1.3), Li _x Mn ₂ O ₄ (0.5 <x <1.3), Li _x (Ni _a Co _b Mn _c ) O ₂ (0.5 <x <1.3, 0 <a <1, 0 <b <1, 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 (0.5 <x <1.3, 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) Lithium secondary battery, characterized in that one or a mixture of two or more thereof.

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