KR100976959B1 - Electrolyte including eutectic mixture and electrochemical device having same - Google Patents

Abstract

The present invention (a) an amide compound in which an amine group of a specific structure is bound with a ring; And (b) an electrolyte comprising an eutectic mixture composed of ionizable lithium salts and an electrochemical device having the same.

Since the eutectic mixture contained in the electrolyte of the present invention has inherent properties of the eutectic mixture such as excellent thermal stability and chemical stability, problems due to evaporation and ignition of the electrolyte are improved.

Electrochemical device, electrolyte, eutectic mixture, amine group, ring

Description

Electrolyte including an eutectic mixture and an electrochemical device having the same {ELECTROLYTE COMPRISING EUTECTIC MIXTURE AND ELECTROCHEMICAL DEVICE CONTAINING THE SAME}

The present invention relates to an electrolyte comprising an eutectic mixture and an electrochemical device having the same.

Electrochemical devices, such as lithium secondary batteries, electrolytic condensers, electric double layer capacitors, electrochromic display devices, and dye-sensitized solar cells, which are being researched for practical use in the future, are widely used in recent years. Various kinds of electrolytes are used in the back, and the importance thereof is increasing day by day.

Currently, the most widely used electrolytes include ionizable salts such as lithium salts such as ethylene carbonate, propylene carbonate, dimethoxy ethane, g-butyl lactone (GBL), N, N It is a non-aqueous electrolyte solution dissolved in an organic solvent such as dimethyl formamide, tetrahydrofurane or acetonitrile.

By the way, the organic solvent used in such a non-aqueous electrolyte solution is not only easy to leak due to the low viscosity, but also highly volatile and may evaporate. It is also highly flammable. Accordingly, the electrochemical device having the same has problems in durability and stability.

In order to solve this problem, a method of using an imidazolium-based and ammonium-based ionic liquid as an electrolyte of a lithium secondary battery has been proposed. However, such an ionic liquid is reduced at a higher voltage than lithium ions at the negative electrode, or imidazolium and ammonium cations are inserted together at the negative electrode together with lithium ions, thereby degrading battery performance.

On the other hand, Korean Patent Registration Publication No. 10-751203, Korean Patent Publication No. 10-2007-85575 and the like have acetamide, urea, methylurea, caprolactam, valerictam, trifluoroacetamide, carbamate, formamide as electrolytes. And the like, and a eutectic mixture of an amide compound represented by a predetermined chemical formula and a lithium salt is disclosed. Since the eutectic mixture exhibits high thermal and chemical stability in addition to a relatively wide electrochemical window, problems such as evaporation and ignition of the electrolyte according to conventional organic solvents are solved.

Accordingly, the development of various eutectic mixtures useful as electrolytes is accelerating.

Accordingly, it is an object of the present invention to provide an electrolyte comprising a novel eutectic mixture exhibiting high thermal and chemical stability and an electrochemical device having the same.

In order to achieve the above object, the electrolyte of the present invention (a) an amide compound in which the amine group represented by the following formula (1) is bound with a ring; And (b) an eutectic mixture consisting of ionizable lithium salts.

In Formula 1,

R is any one selected from the group consisting of hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkylamine group, an alkenyl group, an aryl group, and an alkylaryl group,

X is any one selected from the group consisting of carbon, silicon, oxygen, nitrogen, phosphorus, sulfur and hydrogen, i) m is 0 if X is hydrogen, ii) m is 1 if X is oxygen or sulfur, i) M is 2 if X is nitrogen or phosphorus i) m is 3 if X is carbon or silicon,

W is hydrogen or an alkyl group having 1 to 10 carbon atoms,

Z is any one selected from the group consisting of carbon, oxygen and nitrogen, i) p is 0 if Z is oxygen, ii) p is 1 if Z is nitrogen, iii) p is 2 if Z is carbon,

n is an integer of 1-5.

In the electrolyte of the present invention, the amide compound in which the amine group is ringed preferably includes any one selected from the group consisting of a morpholine group, a triazole group and a pyrimidine group, for example, morpholine methyl carbamate and pyrroli Dine methyl carbamate, imidazole methyl carbamate and the like.

Further, in the electrolyte of the present invention, as the lithium salt, the anion is ^{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 the like can be given ^{_{-, (CF 3 CF 2 SO}} 2) 2 N.

In the electrolyte of the present invention, it is preferable that the molar ratio of the amide compound and lithium salt in which the amine group of the eutectic mixture is bound by a ring is 1 to 8: 1.

In addition, in the electrolyte of the present invention, when the electrolyte is a liquid electrolyte, the eutectic mixture may include 50 to 100% by weight based on the total weight of the liquid electrolyte.

The electrolyte of the present invention described above may be usefully applied to an electrochemical device such as a lithium secondary battery.

 Since the novel eutectic mixture contained in the electrolyte of the present invention exhibits inherent properties of the eutectic mixture such as excellent thermal stability and chemical stability, problems such as evaporation, ignition, side reaction of the electrolyte according to the conventional organic solvents are greatly improved.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

The electrolyte of the present invention includes (a) an amide compound in which an amine group represented by the following formula (1) is bound with a ring; And (b) an eutectic mixture consisting of ionizable lithium salts.

<Formula 1>

In Formula 1,

R is any one selected from the group consisting of hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkylamine group, an alkenyl group, an aryl group, and an alkylaryl group,

X is any one selected from the group consisting of carbon, silicon, oxygen, nitrogen, phosphorus, sulfur and hydrogen, i) m is 0 if X is hydrogen, ii) m is 1 if X is oxygen or sulfur, i) M is 2 if X is nitrogen or phosphorus i) m is 3 if X is carbon or silicon,

W is hydrogen or an alkyl group having 1 to 10 carbon atoms,

Z is any one selected from the group consisting of carbon, oxygen and nitrogen, i) p is 0 if Z is oxygen, ii) p is 1 if Z is nitrogen, iii) p is 2 if Z is carbon,

n is an integer of 1-5.

The present inventors formed an eutectic mixture with a lithium salt using an amide compound in which the amine group having the structure described above is bound with a ring, which is known as an eutectic mixture of an amide compound such as acetamide, methyl carbamate and lithium salt As such, they exhibit high thermal and chemical stability inherent to eutectic mixtures.

In the electrolyte of the present invention, the amide compound in which the amine group of the formula (1) constituting the eutectic mixture is ringed preferably includes any one selected from the group consisting of a morpholine group, a triazole group, and a pyrimidine group. Porin methyl carbamate, pyrrolidine methyl carbamate, imidazole methyl carbamate and the like. In particular, when the morpholine methyl carbamate or pyrrolidine methyl carbamate is used, the reduction potential of the electrochemical window is low, and thus it is more preferable because it can be usefully used as an electrolyte of an electrochemical device to which various negative electrode materials are applied. .

In the electrolyte of the present invention, the lithium salt constituting the eutectic mixture together with the amide compound in which the aforementioned amine group is ringed can be represented by Li ⁺ X ^- as an ionizable lithium salt. In this lithium salt anion is not particularly ^{limited, 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 the like can be given ^{_{-, (CF 3 CF 2 SO}} 2) 2 N.

Melting temperature of the eutectic mixture of the electrolyte according to the present invention may vary according to R, X, W, etc. of the formula (1), preferably a liquid at room temperature (25 ℃), also, the viscosity (viscosity) of the eutectic mixture There is no particular limitation, but 2000 cP or less is preferable.

The eutectic mixture of the electrolyte according to the present invention may be prepared according to a conventional method known in the art, for example, by mixing an amide compound in which the aforementioned amine group is bound with a lithium salt at room temperature, and then suitable at 70 ° C. or lower. After the reaction at the temperature can be prepared by purification. At this time, the molar ratio of the amide compound and lithium salt in which the amine group of the prepared eutectic mixture is bound by a ring is preferably 1 to 8: 1, more preferably 2 to 6: 1.

Since the electrolyte of the present invention includes a eutectic mixture containing lithium ions in itself, even when applied to a lithium secondary battery, a lithium salt may not be added separately, but a salt such as lithium salt may be, for example, 0 to 1 M / L. Of course, the concentration may further include. When further adding a lithium salt to the electrolyte, in order to improve solubility in the electrolyte, it is preferable to use a lithium salt having the same anion as that of the lithium salt constituting the eutectic mixture.

In addition, it will be apparent to those skilled in the art that the electrolyte of the present invention may further include various kinds of additives or organic solvents without departing from the object of the present invention.

Regardless of the type of electrolyte, all of the electrolytes of the present invention may be applied. For example, the electrolyte may be used as a liquid electrolyte or a polymer electrolyte such as a solid or gel phase of the polymer itself. When the electrolyte of the present invention is used as a liquid electrolyte, the above-mentioned eutectic mixture may be used alone, or further added with a salt, an organic solvent, an additive, and the like. The preferred content of the above eutectic mixture in the electrolyte is the total weight of the electrolyte. It is 50 to 100% by weight based on the.

On the other hand, when the electrolyte of the present invention is a polymer electrolyte, the polymer electrolyte is a gel-like polymer by polymerization of a precursor solution containing a eutectic mixture and a monomer capable of forming a polymer by a polymerization reaction, or the eutectic mixture is a solid phase or It may be made of a polymer electrolyte in a form impregnated with a polymer such as gel.

(1) First, the gel polymer electrolyte produced by the polymerization reaction of the precursor solution will be described.

Gel-like polymer electrolyte according to an aspect of the present invention is (i) the eutectic mixture of Formula 1; And (ii) a precursor solution containing a monomer capable of forming a polymer by a polymerization reaction.

As the monomer (monomer) as the polymerization proceeds, all kinds of monomers capable of forming a gel polymer with the eutectic mixture is applicable, non-limiting examples thereof include vinyl monomers. Vinyl monomers have the advantage of very simple polymerization when mixed with eutectic mixtures to form gel polymers.

Non-limiting examples of vinyl monomers that can be used include acrylonitrile, methyl methacrylate, methyl acrylate, methacrylonitrile, methyl styrene, vinyl esters, vinyl chloride, vinylidene chloride, acrylamide, tetrafluoroethylene , Vinyl acetate, vinyl chloride, methyl vinyl ketone, ethylene, styrene, paramethoxy styrene, paracyano styrene, and the like, each of which may be used alone or in combination of two or more thereof.

The precursor solution may additionally include conventional polymerization initiators or photoinitiators, initiators are decomposed by heat or ultraviolet light to form radicals and react with monomers by free radical polymerization to form gel polymer electrolytes. do. Moreover, superposition | polymerization of a monomer can also be advanced, without using an initiator. In general, free-radical polymerization is a reaction of initiation where active molecules or active points are formed, a growth reaction in which monomers are added at the end of an active chain to form an active point at the end of the chain, and a chain transfer that transfers the active point to other molecules. Reaction, a stop reaction in which the active chain center is destroyed.

Non-limiting examples of thermal initiators that can be used include organic peroxides such as Benzoyl peroxide, Acetyl peroxide, Dilauryl peroxide, Di-tert-butyl peroxide, Cumyl hydroperoxide, and Hydrogen peroxide, and hydroperoxides, 2,2-Azobis (2). azo compounds such as -cyanobutane), 2,2-Azobis (Methylbutyronitrile), AIBN (Azobis (iso-butyronitrile), AMVN (Azobisdimethyl-Valeronitrile), and organic metals such as silver alkylated compounds. Non-limiting examples of photoinitiators formed by radicals include Chloroacetophenone, Diethoxy Acetophenone (DEAP), 1-phenyl-2-hydroxy-2-methyl propaneone (HMPP), 1-Hydroxy cyclrohexyl phenyl ketone, α-Amino Acetophenone, Benzoin Ether, Benzyl Dimethyl ketal, Benzophenone, Thioxanthone and 2-ethylAnthraquinone (2-ETAQ).

In addition to the components described above, the precursor solution of the gel polymer electrolyte according to the present invention may optionally contain other additives and the like known in the art.

Using the precursor solution described above to form a gel polymer electrolyte according to a conventional method known in the art, it is preferable to prepare a gel polymer electrolyte by the In - Situ polymerization reaction in the electrochemical device. In - Situ polymerization reaction is possible by heat or ultraviolet irradiation. The content ratio of the eutectic mixture and the monomer in the precursor solution is preferably adjusted to 0.5-0.95: 0.05-0.5. Since the degree of polymerization of the gel polymer can be controlled according to the polymerization time, polymerization temperature or light irradiation degree, which are reaction factors, The polymer is superpolymerized without leaking the electrolyte so that the volume does not shrink.

(2) As another method for producing a polymer electrolyte containing a eutectic mixture according to the present invention, the eutectic mixture may be injected into a solid polymer or a gel polymer already formed, so that the eutectic mixture is impregnated into the polymer.

Non-limiting examples of the polymers that can be used include polymethyl methacrylate, polyvinylidene difluoride, polyvinyl chloride, polyethylene oxide, polyhydroxyethyl methacrylate, etc., alone or in combination of two or more thereof. have. This method can simplify the manufacturing process compared to the In - Situ method described above.

(3) According to the present invention, as another method for preparing a polymer electrolyte containing a eutectic mixture, a method of forming a polymer electrolyte by dissolving the polymer and the eutectic mixture in a solvent and then removing the solvent may be used. At this time, the eutectic mixture is in the form contained in the polymer matrix.

The solvent that can be used is not particularly limited, and non-limiting examples thereof include toluene, acetone, acetonitrile, THF, and the like. In addition, the solvent removal method is not particularly limited, and conventional methods such as applying heat may be used.

The electrolyte comprising the eutectic mixture according to the present invention is applicable to conventional electrochemical devices known in the art which require various electrochemical properties depending on the purpose of use.

Non-limiting examples of the electrochemical device include all kinds of primary, secondary cells, fuel cells, solar cells, electrochromic devices, electrolytic condenser or capacitor (capacitor), specific examples thereof Lithium secondary batteries, electric double layer capacitors, dye-sensitized solar cells, electrochromic devices and the like.

Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example  One

1-1. Morpholine methylcarbamate  synthesis

15 g of methyl chloroformate is added to a round bottom flask and cooled to below 0 ° C. 27.6 g (2 equivalents) of Morpholine is dissolved in tetrahydrofuran (THF) solvent and slowly added dropwise. When the dropping is completed, the temperature is raised to room temperature and then slowly stirred for 2 hours, and the salt generated after the reaction is filtered. The tetrahydrofuran (THF) solvent was removed and then distilled to give 18 g of the desired compound.

1-2. Morpholine Methyl carbamate ( Morpholine methylcarbamate ) / LiPF6 Eutectic mixture  synthesis

2.86 g of purified Morpholine methylcarbamate and 1 g of LiPF6 were placed in a round bottom flask, and stirred slowly under a nitrogen atmosphere for 2 hours to obtain 3.8 g of the desired eutectic mixture.

1-3. Morpholine Methyl carbamate Of LiPF6 Eutectic mixture Heat polymerization  Through gel Polymer  Electrolyte

Morpholine methyl carbamate / LiPF6 eutectic mixture, HEMA (2-hydroxyethylmethacrylate) monomer, synthesized in Example 1-2, AMVN (azobisdimethyl-valeronitrile) as a thermal polymerization initiator was mixed in a weight ratio of 8: 2: 0.01 55 ℃ Polymerization was carried out at temperature for 1 hour to form a gel polymer electrolyte.

1-4. Acetamide - NaSCN Eutectic mixture  Gel by UV Polymerization Polymer  Electrolyte

Morphorin methyl carbamate / LiPF6 eutectic mixture prepared in 1-2, TAEI (tris [2- (acryloyloxy) ethyl] isocyanurate) as a crosslinking agent, MPEGM (methoxy poly (ethylene glycol) methacrylate) monomers, UV polymerization initiator An electrolyte precursor prepared by mixing Irgacure-184 (Shiba) at a mass% of 50: 0.5: 50: 10 was prepared and polymerized by irradiation with ultraviolet rays for 30 minutes to form a gel polymer electrolyte.

Example  2

2-1. Pyrrolidine Methyl carbamate ( Pyrrolidine methylcarbamate ) synthesis

15 g of methyl chloroformate is added to a round bottom flask and cooled to below 0 ° C. 22.6 g (2 equivalents) of pyrrolidine is dissolved in tetrahydrofuran (THF) solvent and slowly added dropwise. When the dropwise addition is completed, the temperature is raised to room temperature, then slowly stirred for 2 hours, and the salt generated after the reaction is filtered. The tetrahydrofuran (THF) solvent was removed and then distilled to give 17 g of the desired compound.

2-2. Pyrrolidine Methyl carbamate ( Pyrrolidine methylcarbamate ) / LiPF6 Euphoric Compound synthesis

The purified insert pyrrolidin-methylcarbamate (Pyrrolidine methylcarbamate) 2.71g and 1g LiPF6 in a round bottom flask, was slowly stirred for 2 hours under a nitrogen atmosphere to give the desired eutectic mixture 3.7g.

2-3. Pyrrolidine Methyl carbamate Of LiPF6 Eutectic mixture Heat polymerization  Through gel Polymer  Electrolyte

Pyrrolidine methyl carbamate / LiPF6 eutectic mixture, HEMA (2-hydroxyethylmethacrylate) monomer, synthesized in Example 2-2, AMVN (azobisdimethyl-valeronitrile) as a thermal polymerization initiator is mixed in a weight ratio of 8: 2: 0.01 55 ℃ The polymer was polymerized at a temperature of 1 hour to form a gel polymer electrolyte.

2-4. Pyrrolidine Methyl carbamate Of LiPF6 Eutectic mixture  Gel polymer electrolyte through ultraviolet polymerization

Pyrrolidine methyl carbamate / LiPF6 eutectic mixture prepared in 2-, TAEI (tris [2- (acryloyloxy) ethyl] isocyanurate) as a crosslinking agent, MPEGM (methoxy poly (ethylene glycol) methacrylate) monomers, UV polymerization initiator An electrolyte precursor prepared by mixing Irgacure-184 (Shiba) at a mass% of 50: 0.5: 50: 10 was prepared and polymerized for 30 minutes by irradiation with ultraviolet rays to form a gel polymer electrolyte.

Example  3

3-1. Imidazole Methyl carbamate ( Imidazole methylcarbamate ) synthesis

10 g of methyl chloroformate is added to a round bottom flask and cooled to 0 ° C or lower. 14.4 g (2 equivalents) of imidazole is dissolved in tetrahydrofuran (THF) solvent and slowly added dropwise. When the dropping is completed, the temperature is raised to room temperature and then slowly stirred for 2 hours, and the salt generated after the reaction is filtered. The tetrahydrofuran (THF) solvent was removed and distilled to give 11 g of the desired compound.

3-2. Imidazole Methyl carbamate ( Imidazole methylcarbamate ) / LiPF6 Eutectic mixing Water synthesis

2.63 g of purified imidazole methylcarbamate and 1 g of LiPF6 were placed in a round bottom flask and stirred slowly for 2 hours under a nitrogen atmosphere to obtain 3.6 g of the desired eutectic mixture.

3-3. Imidazole Methyl carbamate Of LiPF6 Eutectic mixture Heat polymerization  Through gel Polymer  Electrolyte

The imidazole methyl carbamate / LiPF6 eutectic mixture, HEMA (2-hydroxyethylmethacrylate) monomer, and the AMVN (azobisdimethyl-valeronitrile) as a thermal polymerization initiator were mixed in a weight ratio of 8: 2: 0.01 at 55 ° C. Polymerization was carried out at temperature for 1 hour to form a gel polymer electrolyte.

3-4. Imidazole Methyl carbamate Of LiPF6 Eutectic mixture  Gel polymer electrolyte through ultraviolet polymerization

Imidazole methyl carbamate / LiPF6 eutectic mixture prepared in 3-, TAEI (tris [2- (acryloyloxy) ethyl] isocyanurate) as a crosslinking agent, MPEGM (methoxy poly (ethylene glycol) methacrylate) as monomer, Irgacure as UV polymerization initiator A gel polymer electrolyte was prepared by preparing an electrolyte precursor obtained by mixing -184 (Ciba) at a mass% of 50: 0.5: 50: 10 and polymerizing for 30 minutes by irradiating with ultraviolet rays.

In order to evaluate the physical properties of the eutectic mixture according to the above-described embodiment, it was carried out as follows.

As a sample, a eutectic mixture prepared in Examples 1 to 3 was used, and the ratio of the eutectic mixture used was 3: 1 in both amide compound and salt ratio. Viscosity measurements were measured at 25 ° C. using an RS150 viscometer and conductivity was measured using an Inolab 740 instrument. The results are shown in Table 1 below.

Referring to the results of Table 1, in the case of morpholine methyl carbamate and pyrrolidine methyl carbamate, the reduction potential of the electrochemical window was significantly lower than that of the conventional eutectic mixtures, so that various negative electrode materials were applied. It can be usefully applied as an electrolyte of an electrochemical device.

Claims (19)

(a) an amide compound represented by the following formula (1) in which an amine group is bound with a ring; And (b) ionizable lithium salts Electrolyte containing eutectic mixture consisting of: <Formula 1>

In Formula 1, R is any one selected from the group consisting of hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkylamine group, an alkenyl group, an aryl group, and an alkylaryl group, X is any one selected from the group consisting of carbon, silicon, oxygen, nitrogen, phosphorus, sulfur and hydrogen, i) m is 0 if X is hydrogen, ii) m is 1 if X is oxygen or sulfur, i) M is 2 if X is nitrogen or phosphorus i) m is 3 if X is carbon or silicon, W is hydrogen or an alkyl group having 1 to 10 carbon atoms, Z is any one selected from the group consisting of carbon, oxygen and nitrogen, i) p is 0 if Z is oxygen, ii) p is 1 if Z is nitrogen, iii) p is 2 if Z is carbon, n is an integer of 1-5. The electrolyte of claim 1, wherein the amide compound in which the amine group is ringed comprises one selected from the group consisting of a morpholine group, a triazole group, and a pyrimidine group. The method of claim 1, wherein the lithium salt anion is ^{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 - electrolyte, characterized in that at least one selected from the group consisting of. The electrolyte of claim 1, wherein the eutectic mixture has a molar ratio of 1 to 8: 1 to an amide compound in which the amine group is bound with a ring and a lithium salt. The electrolyte of claim 1, wherein the eutectic mixture has a viscosity of 2000 cP or less. The electrolyte of claim 1, wherein the electrolyte further comprises a lithium salt. The electrolyte of claim 6, wherein the anion of the lithium salt is the same as the anion of the lithium salt constituting the eutectic mixture. The electrolyte of claim 6, wherein the concentration of the lithium salt is greater than 0 and less than or equal to 1 M / L. The electrolyte of claim 1, wherein the electrolyte is a liquid electrolyte, and the eutectic mixture is contained in an amount of 50 to 100 wt% based on the total weight of the electrolyte. The electrolyte of claim 1, wherein the electrolyte is a polymer electrolyte. The polymer electrolyte according to claim 10, wherein the polymer electrolyte is a gel polymer electrolyte formed by polymerization of a precursor solution containing (i) the eutectic mixture and (ii) a monomer capable of forming a polymer by a polymerization reaction. Characterized by an electrolyte. 12. The electrolyte according to claim 11, wherein said monomer is a vinyl monomer. The method of claim 12, wherein the vinyl monomer is acrylonitrile, methyl methacrylate, methyl acrylate, methacrylonitrile, methyl styrene, vinyl esters, vinyl chloride, vinylidene chloride, acrylamide, tetrafluoroethylene And vinyl acetate, vinyl chromide, methyl vinyl ketone, ethylene, styrene, paramethoxy styrene, and paracyano styrene. Any one or a mixture of two or more thereof. The electrolyte of claim 11, wherein the content ratio of the eutectic mixture and the monomer in the precursor solution is 0.5-0.95: 0.05-0.5. The electrolyte of claim 11, wherein the gel polymer electrolyte is prepared by in-situ polymerization in an electrochemical device. 11. The electrolyte of claim 10 wherein the polymer electrolyte is impregnated with the eutectic mixture in a polymer. 17. The polymer according to claim 16, wherein the polymer is any one selected from the group consisting of polymethyl methacrylate, polyvinylidene difluoride, polyvinyl chloride, polyethylene oxide and polyhydroxyethyl methacrylate or a mixture of two or more thereof. It is an electrolyte characterized by the above-mentioned. In the electrochemical device comprising a positive electrode, a negative electrode and an electrolyte, The electrolyte is an electrochemical device, characterized in that the electrolyte of any one of claims 1 to 17. 19. The electrochemical device of claim 18, wherein the electrochemical device is a lithium secondary battery.