KR101633966B1 - Composition for gel polymer electrolyte and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a method for producing a lithium secondary battery, comprising: i) an electrolyte solution; ii) an ionizable lithium salt; iii) a polymerization initiator; And iv) a monomer having a functional group capable of binding to a metal ion, and a lithium secondary battery comprising the gel polymer electrolyte.
When the composition for a gel polymer electrolyte of the present invention is applied to a lithium secondary battery. It is possible to improve the lifetime of the battery by preventing the metal ions eluted from the anode from moving to the cathode or reducing the precipitation of the metal from the cathode, and it is possible to improve not only the normal voltage but also the capacity characteristic of the battery Do.

Description

TECHNICAL FIELD [0001] The present invention relates to a composition for a gel polymer electrolyte, and a lithium secondary battery comprising the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a composition for a gel polymer electrolyte and a lithium secondary battery comprising the same, and more particularly, to a gel polymer electrolyte composition comprising a monomer having a functional group capable of binding to a metal ion eluted from an anode, To a lithium secondary battery.

2. Description of the Related Art [0002] The application fields of rechargeable secondary batteries ranging from portable devices such as mobile phones, notebooks, and camcorders to electric vehicles are increasingly being developed, and secondary batteries are being actively developed. In addition, research and development on battery design for improving capacity density and specific energy in the development of secondary batteries are under way.

Generally, the safety of a battery is improved in the order of liquid electrolyte < gel polymer electrolyte &gt; solid polymer electrolyte, while battery performance is known to decrease. Background Art [0002] Electrolytes for electrochemical devices such as batteries and electric double layer capacitors using electrochemical reactions have been mainly used as liquid electrolytes, especially ion conductive organic liquid electrolytes in which salts are dissolved in non-aqueous organic solvents. However, when such a liquid electrolyte is used, there is a possibility that the electrode material is degenerated and the organic solvent is volatilized, and there is a problem in safety such as combustion due to the ambient temperature and the temperature rise of the battery itself.

Solid polymer electrolytes are known to have not yet been commercialized due to inferior cell performance.

On the other hand, the gel polymer electrolyte is excellent in electrochemical safety, so that the thickness of the battery can be maintained constant, and the contact between the electrode and the electrolyte is excellent due to the adhesive force inherent in the gel state, so that the thin film battery can be manufactured. Accordingly, various gel polymer electrolytes are being developed.

In such a gel polymer electrolyte, lithium ions are relatively small in direct migration, and are liable to move to a hopping phenomenon in an electrolyte as shown in FIG. 1.

The lithium secondary battery including the gel polymer electrolyte generally uses a lithium transition metal oxide such as LiCoO ₂ as a cathode active material, but has a problem that metal ions are eluted when used at a high voltage. When the metal ions are eluted, they are reduced from the cathode to the metal state, blocking the reaction site of the cathode. When a new metal is deposited on the cathode surface, the electrolyte creates a new SEI layer on the metal surface, do. Further, the SEI layer of the negative electrode is continuously thickened to increase the resistance, and the lifetime characteristics are deteriorated.

The object of the present invention is to improve the lifetime of a battery by preventing the migration of metal ions eluted from the anode to the cathode or lowering the rate of migration of the metal from the cathode, And a lithium secondary battery including the same, which can improve the capacity characteristics of a battery in both high-voltage and high-voltage regions.

In order to achieve the above object, the present invention provides, in accordance with one embodiment, a method for producing a lithium ion secondary battery comprising: i) an electrolyte solution; ii) an ionizable lithium salt; iii) And iv) a monomer having a functional group capable of binding with a metal ion.

In addition, the present invention provides, in accordance with an embodiment, cathode; A separator; And a gel polymer electrolyte, wherein the gel polymer electrolyte provides a lithium secondary battery obtained by polymerizing the composition for gel polymer electrolyte.

The composition for a gel polymer electrolyte of the present invention contains a monomer having a functional group capable of binding to a metal ion, so that when applied to a lithium secondary battery, the metal ion eluted from the positive electrode is prevented from moving to the negative electrode, The life of the battery can be improved and the capacity characteristics of the battery can be improved in both the normal voltage and the high voltage range.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing the principle of movement of lithium ions when a composition for a gel polymer electrolyte is used. Fig.
FIG. 2 is a graph comparing the degree of metal precipitated in a negative electrode according to the use of a general electrolyte and a composition for a gel polymer electrolyte according to an embodiment of the present invention.
3 is a graph showing the capacity characteristics of the lithium secondary batteries manufactured in Examples 1 to 4 and Comparative Examples 1 to 3. FIG.
4 is a graph showing the capacitance characteristics of the lithium secondary batteries manufactured in Examples 5 and 6 and Comparative Examples 4 and 5.
5 is a graph showing the capacity characteristics of the lithium secondary batteries manufactured in Examples 7 to 10 and Comparative Examples 6 to 8 at 4.3 V high voltage.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

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.

The composition for a gel polymer electrolyte according to an embodiment of the present invention may include an electrolyte solvent, an ionizable lithium salt, a polymerization initiator, and a monomer having a functional group capable of binding with a metal ion.

,

,

,

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로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 포함할 수 있다.The monomer having a functional group is an acrylonitrile or an acrylate monomer, preferably a monomer having a functional group of C ₁ to C ₅ substituted or unsubstituted with alkyl or halogen

,

,

,

,

And

, Or a mixture of two or more thereof.

Representative examples of the monomer having a functional group according to an embodiment of the present invention may be any one selected from the group consisting of the following compounds or a mixture of two or more thereof:

(1) 2-cyanoethyl acrylate;

(2) 2-cyanoethoxyethyl acrylate;

(3) acrylonitrile;

(4) Ethyl (E) -3- (pyridin-2-yl) -acrylate;

(5) Ethyl (E) -3- (4-pyridinyl) -2-propenone salt;

(6) 2-Propenoic acid, 3,3 '- [2,2'-bipyridine] -4,4'-diyl bis-, dimethyl ester;

(7) 2-Propenoic acid, 2- [2,2'-bipyridin] -6-ylethyl ester;

(8) 2-Propenoic acid, 2- [2,2'-bipyridin] -5-ylethyl ester;

(9) 2-Propenoic acid, 2- [2,2'-bipyridin] -4-ylethyl ester;

(10) 2-Propenoic acid, 1,1 '- [[2,2'-bipyridine] -4,4'-diylbis (methylene)] ester;

(11) 2-propenic acid, 1,10-phenanthroline-2, 9-diylbis (methylene) ester;

(12) 2-propenoic acid, 3- (1,10-phenanthroline-2-yl) -, phenylmethyl ester; And

(13) Synthesis of 2-propenoic acid, 2 - [[(1-oxo-2-propenyl) oxy] methyl] -2 - [(1,1-phenanthroline-5-ylmethoxy) - propanediyl ester.

Among them, any one selected from the group consisting of 2-cyanoethyl acrylate, 2-cyanoethoxyethyl acrylate, acrylonitrile and ethyl (E) -3- (pyridin- Or a mixture of two or more of them may be particularly preferably used.

According to one embodiment of the present invention, the monomer having a functional group is contained in the monomer so that the functional group can be stably fixed on the gel structure in the gel polymer electrolyte.

For example, when a complex is formed by adding a cyano group and an acrylate to a composition for a gel polymer electrolyte (gel electrolyte), the complex itself may migrate in the gel polymer electrolyte composition, resulting in reduction at the cathode, Metal may be precipitated. However, when 2-cyanoethyl acrylate is used as the monomer having a functional group as in the embodiment of the present invention, the cyano group is included in the monomer having the functional group, It can become impossible.

That is, according to one embodiment of the present invention, as shown in FIG. 2, when the monomer having the functional group is used in the composition for a gel polymer electrolyte, a general electrolytic solution in which metal ions eluted from the positive electrode are deposited on the negative electrode Unlike the case where the metal is used, precipitation of metal from the anode by binding with the metal ion eluted from the anode can be reduced. As a result, the charging / discharging efficiency of the lithium secondary battery can be improved and good cycle characteristics can be exhibited. In addition, when the composition for a gel polymer electrolyte containing a monomer having a functional group is applied to a lithium secondary battery, capacity characteristics can be improved in both a normal voltage and a high voltage region.

As used herein, the term &quot; general voltage &quot; means the case where the charging voltage of the lithium secondary battery is in the range of 3.0 V to 4.3 V and the term &quot; high voltage &quot; .

The monomer having the functional group may be 0.1% by weight to 10% by weight, preferably 0.5% by weight to 5% by weight based on the total weight of the composition for a gel polymer electrolyte. When the amount is less than 0.1% by weight, gelation is difficult and gel polymer electrolyte characteristics may not be exhibited. If the amount is more than 10% by weight, the resistance may increase due to excessive monomer content, and battery performance may be deteriorated.

According to an embodiment of the present invention, the composition for a gel polymer electrolyte may further comprise a monomer having 2 to 6 acrylate groups, and the monomer may be a branched monomer.

The branched monomer may be, for example, any one selected from the group consisting of ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, or a mixture of two or more thereof .

The branched monomers may be contained in an amount of 0.1 wt% to 10 wt%, preferably 0.5 wt% to 5 wt% based on the total weight of the composition for a gel polymer electrolyte.

According to an embodiment of the present invention, when the electrolyte composition additionally contains a branched monomer, the monomer having a functional group and the branched monomer are mixed and heated at a temperature ranging from 30 ° C to 100 ° C for 2 minutes to 12 hours To produce a polymerizable monomer. In this case, the content ratio of the functional monomer and the branched monomer may be, for example, 1: 0.1 to 10: 1, but is not limited thereto.

The ionizable lithium salt included in the composition for an electrolyte according to an embodiment of the present invention includes LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , CF ₃ SO ₃ Li, LiC (CF ₃ SO ₂ ) ₃ and LiC ₄ BO ₈ , or a mixture of two or more thereof. It is not.

As the electrolyte solvent used according to one embodiment of the present invention, those commonly used in an electrolyte for a lithium secondary battery may be used without limitation, and for example, ether, ester, amide, linear carbonate, or cyclic carbonate may be used alone Or a mixture of two or more thereof.

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, A carbonate, a vinylene carbonate, and a halide thereof, or a mixture of two or more thereof. Specific examples of the linear carbonate compound include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate , Or a mixture of two or more thereof may be used. However, the present invention is not limited thereto.

In particular, propylene carbonate and ethylene carbonate, which are cyclic carbonates in the carbonate electrolyte solution, are highly viscous organic solvents having a high dielectric constant and can dissociate the lithium salt in the electrolytic solution well. Thus, cyclic carbonates such as ethylmethyl carbonate, diethyl carbonate Or a low viscosity, low dielectric constant linear carbonate such as dimethyl carbonate in an appropriate ratio can be used to more advantageously use an electrolytic solution having a high electrical conductivity.

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

In the present invention, as the polymerization initiator, conventional polymerization initiators known in the art can be used.

Non-limiting examples of the polymerization initiator include benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, organic peroxides such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide and hydrogen peroxide, and hydroperoxides such as hydroperoxide, Azobis (isobutyronitrile) and AMVN (2-cyanobutane), 2,2'-azobis (methylbutyronitrile), AIBN , 2'-azobisdimethyl-valeronitrile), and the like, but the present invention is not limited thereto.

The polymerization initiator may be decomposed by heat in a battery, in a non-limiting example, at 30 ° C to 100 ° C or decomposed at room temperature (5 ° C to 30 ° C) to form radicals and react with a polymerizable monomer by free radical polymerization Gel polymer electrolyte can be formed.

The polymerization initiator may be used in an amount of 0.01 wt% to 2 wt% based on the total weight of the composition for a gel polymer electrolyte. When the amount of the polymerization initiator is more than 2 parts by weight, gelation occurs too early or the unreacted initiator remains after the liquid polymer composition is injected into the cell, which adversely affects battery performance. Conversely, if the amount of the polymerization initiator is less than 0.01 part by weight There is a problem that the gelation is not performed well.

The composition for a gel polymer electrolyte according to an embodiment of the present invention may optionally contain other additives known in the art in addition to the components described above.

According to an embodiment of the present invention, cathode; A separator; And a gel polymer electrolyte, wherein the gel polymer electrolyte is formed by polymerizing a composition for the gel polymer electrolyte. The gel polymer electrolyte according to one embodiment of the present invention Is formed by polymerizing a composition for a gel polymer electrolyte according to a conventional method known in the art. For example, the gel polymer electrolyte may be formed by in- situ polymerization of the gel polymer electrolyte composition in the interior of the secondary battery.

(A) inserting an electrode assembly made of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode into a battery case, and (b) And then polymerizing the gel polymer electrolyte to form a gel polymer electrolyte.

The in - situ polymerization in the lithium secondary battery can proceed through thermal polymerization. In this case, the polymerization time is about 2 minutes to 12 hours, and the thermal polymerization temperature is 30 to 100 ° C.

When the gelation by the polymerization reaction is carried out, a gel polymer electrolyte is formed. Specifically, a gel polymer in which polymerizable monomers are crosslinked with each other by a polymerization reaction is formed, and a liquid electrolyte in which an electrolyte salt is dissociated into an electrolyte solvent can be uniformly impregnated in the formed gel polymer.

The lithium secondary battery according to an embodiment of the present invention has a charging voltage in the range of 3.0 V to 5.0 V and is excellent in capacity characteristics of a lithium secondary battery in both normal voltage and high voltage regions.

According to an embodiment of the present invention, the electrode of the lithium secondary battery may be manufactured by a conventional method known in the art. For example, a slurry may be prepared by mixing and stirring a solvent, if necessary, a binder, a conductive agent, and a dispersant in an electrode active material, coating the electrode active material with a collector of a metal material, have.

According to one embodiment of the present invention, the positive electrode active material in the positive electrode may be applied to a general voltage or a high voltage, and may be used without limitation as long as it is a compound capable of reversibly intercalating / deintercalating lithium.

In the lithium secondary battery according to an embodiment of the present invention, the cathode active material that can be applied to a general voltage includes, for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNi _{1 -y} Co _y O _{2 Y} ? 1 <y <1), LiNi _{1 -y} Mn _y O ₂ (O _{? Y} <1), and LiCo _1-y Mn _y O ₂ , Li [Ni _a Co _b Mn _c ] O ₂ (0 <a, b, c? 1, a + b + c = 1) or a mixture of two or more thereof , But are not limited thereto. In addition to these oxides, sulfide, selenide and halide may also be included.

In the lithium secondary battery according to another embodiment of the present invention, the cathode active material applicable to a high voltage may be a lithium transition metal oxide of spinel having a multilayer salt rock structure having a high capacity characteristic, an olivine structure, a cubic structure, But may also include any one selected from the group consisting of V ₂ O ₅ , TiS, and MoS, or a composite oxide of two or more thereof. More specifically, it may include, for example, any one selected from the group consisting of oxides of the following general formulas (1) to (3), or a mixture of two or more thereof:

&Lt; Formula 1 >

Li [Li _x Ni _a Co _b Mn _c ] O ₂ (0 <x? 0.3, 0.3? C? 0.7, 0 <a + b <0.5, x + a + b + c = 1);

(2)

LiMn _{2 - x} M _x O ₄ (M = at least one element selected from the group consisting of Ni, Co, Fe, P, S, Zr, Ti and Al, 0 <x? 2);

(3)

Li, Zr, Ce, In, Zn and Y are selected from the group consisting of Li _{1 + a} Co _x M _{1 - x} AX ₄ (M = Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, X is at least one element selected from the group consisting of O, F and N, A is P, S or a mixed element thereof, and 0? A? 0.2 and 0.5? X? 1.

Preferably, the cathode active material is one selected from the group consisting of LiNi _0.5 Mn _1.5 O ₄ , LiCoPO ₄ and LiFePO ₄ , and 0.4? C? 0.7 and 0.2? A + b < Or mixtures thereof.

Meanwhile, in the lithium secondary battery according to an embodiment of the present invention, the anode active material may be a carbonaceous material, lithium metal, silicon, tin, or the like, from which lithium ions can be occluded and released. Preferably, carbon materials can be used, and carbon materials such as low-crystalline carbon and highly-crystalline carbon can 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 anode and / or the cathode can be prepared by preparing a slurry by mixing and stirring a binder and a solvent, a conductive agent and a dispersant, which can be conventionally used according to need, applying the slurry to a current collector, and compressing the anode to produce a cathode.

Examples of the binder include polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM) Various kinds of binder polymers such as sulfonated EPDM, styrene butylene rubber (SBR), fluorine rubber, and various copolymers can be used.

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

The outer shape of the lithium secondary battery according to an embodiment of the present invention is not particularly limited, but may be cylindrical, square, pouch type, coin type, or the like using a can.

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 may 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

EXAMPLES The present invention will be further illustrated by the following examples and experimental examples, but the present invention is not limited by these examples and experimental examples.

Example  One

&Lt; Preparation of composition for gel polymer electrolyte &

An electrolytic solution was prepared by dissolving LiPF ₆ in a non-aqueous electrolyte solvent having a composition of ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1: 2 (volume ratio) so as to have a concentration of 1M. 5 parts by weight of a polymerizable monomer (2.5 parts by weight of 2-cyanoethyl acrylate and 2.5 parts by weight of ditrimethylolpropane tetraacrylate were mixedly used) per 100 parts by weight of the electrolytic solution and t-butylperoxy-2 -Ethyl hexanoate was added to prepare a gel polymer electrolyte composition.

<Preparation of coin-shaped secondary battery>

Anode manufacturing

94 wt% of LiCoO ₂ as a positive electrode active material, 3 wt% of carbon black as a conductive agent, and 3 wt% of PVdF as a binder were added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode mixture slurry Respectively. The positive electrode mixture slurry was applied to an aluminum (Al) thin film having a thickness of about 20 mu m and dried to produce a positive electrode, followed by roll pressing to produce a positive electrode.

Cathode manufacture

A negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive material to 96 wt%, 3 wt% and 1 wt%, respectively, as a solvent. The negative electrode mixture slurry was applied to a copper (Cu) thin film as an anode current collector having a thickness of 10 mu m and dried to prepare a negative electrode, followed by roll pressing to produce a negative electrode.

Battery Manufacturing

The battery was assembled using the positive electrode, the negative electrode and a separator composed of three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP). The prepared gel polymer electrolyte composition was injected into the assembled battery, For 2 to 30 minutes to prepare a coin-type secondary battery.

Example  2

Except that 2-cyanoethoxyethyl acrylate was used instead of 2-cyanoethyl acrylate in the preparation of the composition for a gel polymer electrolyte of Example 1, a coin-type secondary battery was obtained in the same manner as in Example 1, .

Example  3

A coin-type secondary battery was produced in the same manner as in Example 1, except that acrylonitrile was used instead of 2-cyanoethyl acrylate in the preparation of the composition for gel polymer electrolyte of Example 1.

Example  4

Example 1 was repeated except that ethyl (E) -3- (pyridin-2-yl) -acrylate was used instead of 2-cyanoethyl acrylate in the preparation of the gel polymer electrolyte composition of Example 1 The coin type secondary battery was manufactured in the same manner.

Example  5

Except that a mixture of LiMn ₂ O ₄ and Li (Ni _0.33 Co _0.33 Mn _0.33 ) O ₂ 3: 7 weight ratio as a cathode active material was used in the production of the coin type secondary battery of Example 1, A coin-type secondary battery was manufactured.

Example  6

In the preparation of the gel polymer electrolyte composition of Example 1, 2-cyanoethoxyethyl acrylate was used instead of 2-cyanoethyl acrylate, and LiMn ₂ O ₄ and LiMn ₂ O ₄ were used as the positive electrode active material in the production of coin- Li (Ni co _{0 .33 0 .33 0 .33} Mn) ₂ O 3: was prepared in example 1, and the coin type secondary battery in the same manner except that the mixture was mixed in a weight ratio of 7.

Example  7

A coin type secondary battery was produced in the same manner as in Example 1, except that Li [Li _0.29 Ni _0.14 Co _0.11 Mn _0.46 ] O ₂ was used instead of LiCoO ₂ as the positive electrode active material in the production of the positive electrode of Example 1.

Example  8

Example 1 In the preparation of the gel polymer electrolyte composition, 2-cyanoethyl acrylate instead of 2-cyano according to the manufacture use of ethoxyethyl acrylate, and the positive electrode, LiCoO ₂ instead of Li [Li ₀ as the positive electrode active _{material. 29} Ni _{0 .14} was prepared a coin-type secondary cell in the same manner as in example 1 except for using _{co 0 .11 Mn 0 .46] O} 2.

Example  9

For Example 1 Preparation of a gel polymer electrolyte composition, instead of the 2-cyanoethyl acrylate in, and the positive electrode prepared using acrylonitrile, instead of LiCoO ₂ Li [Li _{0 .29 0 .14} Co as a cathode active material Ni _{0 .11} Mn _{0 .46} ] O ₂ was used as a negative electrode active material, a coin type secondary battery was produced.

Example  10

(E) -3- (pyridin-2-yl) -acrylate was used in place of 2-cyanoethyl acrylate in the preparation of the gel polymer electrolyte composition of Example 1, A coin type secondary battery was produced in the same manner as in Example 1, except that Li [Li _{0 .29} Ni _{0 .14} Co _{0 .11} Mn _{0 .46} ] O ₂ was used instead of LiCoO ₂ .

Comparative Example  One

A coin-type secondary battery was prepared in the same manner as in Example 1, except that the polymerizable monomer and the polymerization initiator were not used in the preparation of the composition for gel polymer electrolyte of Example 1.

Comparative Example  2

In the preparation of the composition for a gel polymer electrolyte of Example 1, 5 parts by weight of a polymerizable monomer prepared by mixing 2.5 parts by weight of 2-cyanoethyl acrylate and 2.5 parts by weight of ditrimethylolpropane tetraacrylate was used instead of ditrimethylol And 5 parts by weight of propane tetraacrylate were used alone to prepare a coin type secondary battery.

Comparative Example  3

In the preparation of the gel polymer electrolyte composition of Example 1, 5 parts by weight of the polymerizable monomer prepared by mixing 2.5 parts by weight of 2-cyanoethyl acrylate and 2.5 parts by weight of ditrimethylolpropane tetraacrylate was used instead of dipentaerythritol A coin-type secondary battery was produced in the same manner as in Example 1, except that 5 parts by weight of lithol pentaacrylate was used alone.

Comparative Example  4

A coin-type secondary battery was produced in the same manner as in Example 5, except that the polymerizable monomer and the polymerization initiator were not used in the preparation of the composition for a gel polymer electrolyte of Example 5.

Comparative Example  5

In the preparation of the composition for a gel polymer electrolyte of Example 5, 5 parts by weight of a polymerizable monomer prepared by mixing 2.5 parts by weight of 2-cyanoethyl acrylate and 2.5 parts by weight of ditrimethylolpropane tetraacrylate was used instead of ditrimethylol And 5 parts by weight of propane tetraacrylate were used alone to prepare a coin type secondary battery.

Comparative Example  6

A coin-type secondary battery was produced in the same manner as in Example 7, except that the polymerizable monomer and the polymerization initiator were not used in the preparation of the composition for a gel polymer electrolyte of Example 7.

Comparative Example  7

In the preparation of the composition for a gel polymer electrolyte of Example 7, 5 parts by weight of a polymerizable monomer prepared by mixing 2.5 parts by weight of 2-cyanoethyl acrylate and 2.5 parts by weight of ditrimethylolpropane tetraacrylate was used instead of ditrimethylol And 5 parts by weight of propane tetraacrylate were used alone, to prepare a coin-type secondary battery.

Comparative Example  8

Instead of using 5 parts by weight of the polymerizable monomer prepared by mixing 2.5 parts by weight of 2-cyanoethyl acrylate and 2.5 parts by weight of ditrimethylolpropane tetraacrylate in the preparation of the gel polymer electrolyte composition of Example 7, A coin-type secondary battery was produced in the same manner as in Example 7 except that 5 parts by weight of lithol pentaacrylate was used alone.

Experimental Example  1: Capacity characteristics 1

The lithium secondary battery (battery capacity: 5.5 mAh) produced in Examples 1 to 4 and Comparative Examples 1 to 3 was charged at a constant current of 0.7 C at a temperature of 55 DEG C to 4.2 V and then charged at a constant voltage of 4.2 V, The charging was terminated. After that, it was left for 10 minutes and then discharged at a constant current of 0.5 C until it reached 3.0 V. [ The battery was charged and discharged for 100 cycles, and the battery capacity was measured and shown in FIG.

Specifically, as shown in FIG. 3, the capacities of Examples 1 to 4 and Comparative Examples 1 to 3 were similar under the fifth cycle, but the capacities of Comparative Examples 1 to 3 rapidly decreased after about the 20th cycle, In Examples 1 to 4, there was almost no change in capacity until the 20th cycle. In Examples 1 to 4, the capacity change slope was gentle even at the 100th cycle, and the capacity characteristics were 2 to 3 times higher than those of Comparative Examples 1 to 3.

Therefore, it can be seen that the discharge capacity after 100 cycles of the cells prepared in Examples 1 to 4 was greatly improved as compared with the batteries prepared in Comparative Examples 1 to 3.

Experimental Example  2: Capacity characteristics 2

The lithium secondary batteries (battery capacity: 2.5 mAh) produced in Examples 5 and 6 and Comparative Examples 4 and 5 were charged at 45 ° C. until a constant current of 4.2 V was applied at a temperature of 45 ° C. and then charged at a constant voltage of 4.2 V, The charging was terminated. After that, it was left for 10 minutes and then discharged at a constant current of 0.5 C until it reached 3.0 V. [ The battery was charged and discharged for 100 cycles, and the battery capacity was measured and shown in FIG.

Specifically, as shown in FIG. 4, the capacities of Examples 5 and 6 and Comparative Examples 4 and 5 were almost similar until the 50th cycle, but after the 60th cycle, the capacities of Comparative Examples 4 and 5 began to decrease, And decreased rapidly at times. On the other hand, in Examples 5 and 6, the capacity change slope remained almost unchanged even up to the 100th cycle, and in the 100th cycle, the capacity characteristics of Examples 5 and 6 were two to three times higher than those of Comparative Examples 4 and 5.

Therefore, it can be seen that the discharge capacity after 100 cycles of the cells prepared in Examples 5 and 6 was greatly improved as compared with the batteries prepared in Comparative Examples 4 and 5.

Experimental Example  3: Capacitance characteristic 3 (high voltage)

The lithium secondary batteries (battery capacity: 4.3 mAh) produced in Examples 7 to 10 and Comparative Examples 6 to 8 were charged at 55 DEG C until a constant current of 0.7 C was reached at 4.3 DEG C and then charged at a constant voltage of 4.3 V to charge When the current reached 0.215 mA, charging was terminated. After that, it was left for 10 minutes and then discharged at a constant current of 0.5 C until it reached 3.0 V. [ The battery was charged and discharged for 40 cycles, and the battery capacity was measured and shown in FIG.

Specifically, referring to FIG. 5, the capacities of Examples 7 to 10 and Comparative Examples 6 to 8 were similar at less than about 5th cycle, but the capacity of Comparative Example 6 rapidly decreased after about the fifth cycle, 7 was sharply decreased after the 30th cycle, and after the 20th cycle of Comparative Example 8. On the other hand, in Examples 7 to 10, the capacity change was moderate to the 40th cycle as compared with those of Comparative Examples 6 to 8. In the case of Examples 8 and 9 using 2-cyanoethoxyethyl acrylate and acrylonitrile, At a high voltage, and showed a capacitance characteristic of 2 to 4 times that of Comparative Examples 6 to 8. As a result,

Therefore, it can be seen that the batteries manufactured in Examples 7 to 10 were charged at a high voltage of 4.3 V, and the discharge capacity after 40 cycles was significantly improved as compared with the secondary batteries prepared in Comparative Examples 6 to 8. [

Claims (19)

i) electrolyte solvent,
ii) an ionizable lithium salt,
iii) a polymerization initiator; And
iv) a monomer having a functional group capable of binding to a metal ion
A composition for a gel polymer electrolyte, comprising:
The monomers are selected from the group consisting of C ₁ to C ₅ alkyl or halogen substituted or unsubstituted

,

,

,

, And

, Or an acrylate-based monomer having at least two functional groups selected from the group consisting of these.
delete delete The method according to claim 1,
Wherein the monomer having a functional group is any one selected from the group consisting of the following compounds or a mixture of two or more thereof:
(1) Ethyl (E) -3- (pyridin-2-yl) -acrylate;
(2) ethyl (E) -3- (4-pyridinyl) -2-propenone salt;
(3) 2-Propenoic acid, 3,3 '- [2,2'-bipyridine] -4,4'-diyl bis-, dimethyl ester;
(4) 2-Propenoic acid, 2- [2,2'-bipyridin] -6-ylethyl ester;
(5) 2-Propenoic acid, 2- [2,2'-bipyridin] -5-ylethyl ester;
(6) 2-Propenoic acid, 2- [2,2'-bipyridin] -4-ylethyl ester;
(7) 2-Propenoic acid, 1,1 '- [[2,2'-bipyridine] -4,4'-diylbis (methylene)] ester;
(8) 2-Propenic acid, 1,10-phenanthroline-2, 9-diylbis (methylene) ester;
(9) 2-propenoic acid, 3- (1,10-phenanthroline-2-yl) -, phenylmethyl ester; And
(10) Synthesis of 2 - [(1-oxo-2-propenyl) - propanediyl ester.
The method according to claim 1,
Wherein the composition further comprises a monomer having 2 to 6 acrylate groups, and the monomer is a branched monomer.
6. The method of claim 5,
Wherein the branched monomer is any one selected from the group consisting of ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, or a mixture of two or more thereof. Composition for electrolyte.
The method according to claim 1,
Wherein the functional group-containing monomer is contained in an amount of 0.1% by weight to 10% by weight based on the total weight of the composition.
6. The method of claim 5,
Wherein the branched monomer is contained in an amount of 0.1% by weight to 10% by weight based on the total weight of the composition.
6. The method of claim 5,
Wherein the content ratio of the monomer having a functional group to the branching monomer is 1: 0.1 to 10: 1 by weight.
The method according to claim 1,
The lithium salt is _{LiPF 6, LiBF 4, LiSbF 6} , LiAsF 6, LiClO 4, LiN (C 2 F 5 SO 2) 2, LiN (CF 3 SO 2) 2, CF 3 SO 3 Li, LiC (CF 3 SO ₂ ) ₃ and LiC ₄ BO ₈ , or a mixture of two or more thereof.
The method according to claim 1,
Wherein the electrolyte solvent is a linear carbonate, a cyclic carbonate, or a combination thereof.
12. The method of claim 11,
Wherein the linear carbonate includes any one selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate and ethyl propyl carbonate, or a mixture of two or more thereof, A group consisting of a carbonate, a propylene carbonate, a 1,2-butylene carbonate, a 2,3-butylene carbonate, a 1,2-pentylene carbonate, a 2,3-pentylene carbonate, a vinylene carbonate, Or a mixture of two or more thereof.
anode; cathode; A separator; And a gel polymer electrolyte, the lithium secondary battery comprising:
Wherein the gel polymer electrolyte is obtained by polymerizing the gel polymer electrolyte composition of claim 1.
14. The method of claim 13,
Wherein the composition for gel polymer electrolyte further comprises a monomer having 2 to 6 acrylate groups, and the monomer is a branched monomer.
15. The method of claim 14,
Wherein the branched monomer is any one selected from the group consisting of ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, or a mixture of two or more thereof. battery.
14. The method of claim 13,
Wherein the charging voltage of the lithium secondary battery is 3.0 V to 5.0 V.
17. The method of claim 16,
Wherein the lithium secondary battery has a charging voltage of 4.3V to 5.0V.
The method according to claim 13 or 17,
Wherein the positive electrode active material of the positive electrode is any one selected from the group consisting of oxides of the following formulas (1) to (3) or a mixture of two or more thereof:
&Lt; Formula 1 >
Li [Li _x Ni _a Co _b Mn _c ] O ₂ (0 <x? 0.3, 0.3? C? 0.7, 0 <a + b <0.5, x + a + b + c = 1);
(2)
LiMn _2-x M _x O ₄ (M = at least one element selected from the group consisting of Ni, Co, Fe, P, S, Zr, Ti and Al, 0 <x? 2);
(3)
_{Li 1 + a Co x M 1} -x AX 4 (M = Al, Mg, Ni, Co, Mn, Ti, Ga, selected from the group consisting of Cu, V, Nb, Zr, Ce, In, Zn , and Y X is at least one element selected from the group consisting of O, F and N, A is P, S or a mixed element thereof, and 0? A? 0.2 and 0.5? X? 1.
17. The method according to claim 13 or 16,
The positive electrode active material of the anode is _{LiCoO 2, LiNiO 2, LiMnO 2} , LiMn 2 O 4, LiNi 1-y Co y O 2 (O≤y <1), LiCo 1-y Mn y O 2 (O≤y <1 ), LiNi _1-y Mn _y O ₂ (O _{? Y} <1), and Li [Ni _a Co _b Mn _c ] O ₂ (0 <a, b, c? 1, a + b + , Or a mixture of two or more thereof.

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