KR100975898B1 - Ether-substituted imidazolium type zwitterion and electrolyte for lithium battery comprising the same - Google Patents

Abstract

The present invention relates to an imidazolium-based amphoteric ion in which an ether group and a sulfonate group are substituted, a method for preparing the same, an electrolyte composition containing the same, and a lithium secondary battery including the electrolyte composition. The electrolyte composition for a lithium secondary battery containing an imidazolium-based amphoteric ion substituted with an ether group and a sulfonate group of the present invention as an additive is remarkably excellent in electrochemical stability and charge / discharge performance.

Lithium secondary battery, electrolyte, additive, imidazolium-based amphoteric ion

Description

Imidazolium-based amphoteric ion substituted with an ether group, and an electrolyte composition for a lithium secondary battery comprising the same {ETHER-SUBSTITUTED IMIDAZOLIUM Type

The present invention relates to an imidazolium-based amphoteric ion in which an ether group and a sulfonate group are substituted, a method for preparing the same, an electrolyte composition containing the same, and a lithium secondary battery including the electrolyte composition. More specifically, the present invention provides an imidazolium sulfonated amphoteric ion having an ether group introduced at the C-2 position, a method for preparing the same, an electrolyte composition having excellent electrochemical stability, and a charge / discharge performance of a lithium secondary battery. It relates to a lithium secondary battery comprising the electrolyte composition.

A battery is a device that converts chemical energy into electrical energy through oxidation-reduction reactions of chemical substances.It is a primary battery that must be discarded when internal energy is depleted due to irreversible reaction according to its use characteristics. It can be divided into a rechargeable secondary battery. Recently, due to the rapid development of the electronics, telecommunications, and computer industries, the use of portable electronic products such as camcorders, mobile phones, and notebook computers has become common, and the interest and demand for miniaturization, light weight, and high functionality of devices have increased. Much research is being done. Among the high-performance secondary batteries currently commercially available and commercially available, lithium ion batteries are the most recently developed batteries. Li-ion batteries have high energy density, rapid charge and discharge characteristics, and excellent cycle performance, and are rapidly expanding their markets to mobile phones and notebook computer batteries.

The electrolyte solution of the lithium secondary battery is composed of a solvent and a lithium salt, and in some cases, additives are added to improve the characteristics of the battery or to improve the problem. As a solvent, an aprotic mixed organic compound containing cyclic or chain carbonates such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) Solvents are widely used, and lithium salts include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), and lithium bis (trifluoromethanesulfonyl) imide ( LiN (SO ₂ CF ₃ ) ₂ ), lithium bis (perfluoroethanesulfonyl) imide (LiN (SO ₂ CF ₂ CF ₃ ) ₂ ), and the like are generally used.

During initial charging of the lithium secondary battery, lithium ions in the electrolyte are reduced and inserted between the carbon electrodes as the negative electrodes, and lithium metal oxides as the positive electrodes are dissolved in the electrolyte to maintain the lithium ion concentration of the electrolyte. In this process, lithium ions and organic solvents or anions of lithium salts are partially decomposed and a thin solid electrolyte interface (SEI) film is formed on the surface of the carbon electrode. It serves as a kind of passage to help the movement, and the organic solvent, which has a higher molecular weight than lithium ions, is inserted between the carbon electrodes and prevents the electrode structure from being destroyed. Therefore, the components and structure of the SEI film formed on the surface of the negative electrode during initial charging of the battery have a great influence on the stability and charge / discharge characteristics of the battery. That is, when the SEI film is excessively generated, it may block the passage of lithium ions and thus may not smoothly charge and discharge the battery, thereby reducing battery performance. On the other hand, if the SEI film is not formed stably, the organic solvent may be excessively introduced into the carbon electrode to promote further decomposition of the organic solvent or to swell the electrode. Therefore, in order to implement a high performance secondary battery, development of a functional additive capable of forming a stable SEI film by dissolving at a lower potential than an organic solvent first has been urgently required.

Organic solvents known to form SEI on the surface of the carbon electrode include EC, vinyl carbonate (VC), DMC, EMC, and the like. In order to minimize deterioration of battery performance due to reduction decomposition reaction of organic solvent, Japanese Patent Laid-Open No. 7-176323), sulfide compound (Japanese Patent Laid-Open No. 7-320779), vinyl ester compound (Korean Patent No. 10-0412527), perfluorinated sulfone and divinyl sulfone (Korean Patent No. 10-0485901 No.), vinyl silane-based and borate-based compound (Korean Patent No. 10-0736909) and the like has been proposed a method of adding as an additive.

Recently, due to the excellent properties such as non-volatile, non-flammable and high ionic conductivity, research has been actively conducted to use an ionic liquid as an additive for a secondary battery electrolyte. In particular, research on imidazolium-based ionic liquids has been most extensively conducted. However, since imidazolium has been reported to dissociate protons at the C-2 position relatively easily and cause side reactions on the electrode surface, studies on imidazolium substituted with an alkyl group at the C-2 position to overcome this problem. Although has been made, due to problems such as a decrease in the ionic conductivity due to the relatively high viscosity compared to the organic solvent, there are not many applications for the battery.

Meanwhile, McFarlane et al. At the University of Monash, Australia, reported a study on the electrochemical stability of lithium salt solution of zwitterion compound of pyrrolidinium structure substituted with propanesulfonate. (Advanced Materials 2005, 17, 2497; WO 2006/017898).

Efforts have been made to improve the charging and discharging performance of secondary batteries by forming a stable SEI film during initial charging by using a small amount of an organic or inorganic material as an additive. However, the irreversible capacity may be increased depending on the characteristics of the added compound. There is still much room for improvement, such as forming a decomposed or unstable film by reacting with a carbon electrode, which is a cathode or a cathode. In particular, this tendency was more severe at high temperatures and at high rates of charge and discharge.

In order to solve the above problems, the present inventors are stable on the surface of the carbon negative electrode to improve the mobility of lithium ions to the carbon negative electrode during the charge and discharge of the lithium secondary battery and to reduce the battery performance by the insertion and reaction of the organic solvent While investigating to develop a new additive to help form the SEI film, an ether functional group was introduced at the C-2 position to improve the electrochemical stability of the imidazolium-based amphoteric ion. Compared to the significantly improved electrochemical stability and charging and discharging performance of the lithium secondary battery was confirmed to complete the present invention.

Accordingly, it is an object of the present invention to provide imidazolium-based amphoteric ions substituted with ether and sulfonate groups which are thermally and electrochemically stable.

Another object of the present invention is to provide a method for easily and economically preparing the zwitterions.

Another object of the present invention is to provide an electrolyte composition containing the zwitterion as an additive.

Still another object of the present invention is to provide a lithium secondary battery including the electrolyte composition.

The present invention relates to imidazolium-based amphoteric ions substituted with an ether group and a sulfonate group represented by the formula (1), which can be used as an additive of an electrolyte for a lithium secondary battery.

[Formula 1]

Where

n is an integer of 3 or 4,

m is an integer of 1 or 2,

R ₁ And R ₂ is Each independently is an alkenyl group of C ₁ -C ₆ alkyl group or a C ₁ -C _6.

Preferably, n is 3, m is 1 and R ₁ And R ₂ is Each independently represents an alkyl group of C ₁ -C ₆ . More preferably, R ₁ is methyl, ethyl, propyl or butyl, most preferably methyl and R ₂ is butyl.

In the present specification, an alkyl group of C ₁ -C ₆ means a straight or branched hydrocarbon having 1 to 6 carbon atoms, and examples include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, and the like. no.

In addition, an alkenyl group of C ₁ -C ₆ means an unsaturated hydrocarbon having a straight or branched double bond composed of 1 to 6 carbon atoms, and includes, for example, ethyleneyl, propyleneyl, butyleneyl, and the like. It doesn't happen.

On the other hand, the present invention relates to a method for producing an imidazolium-based amphoteric ion in which the ether group and sulfonate group represented by Chemical Formula 1 are substituted. More specifically, the present invention

(i) As shown in Scheme 1, imidazole and paraformaldehyde are reacted to obtain 2-hydroxyalkylimidazole, which is reacted with alkyl halide or alkenyl halide in the presence of a base to convert ether group to imidazole. Obtaining; And

(ii) represented by the formula (1) comprising reacting the imidazole substituted with the ether group obtained in step (i) with 1,3-propanesultone or 1,4-butanesultone, as shown in Scheme 2 below It relates to a method for producing amphoteric ions.

Scheme 1

Scheme 2

Where

n is an integer of 3 or 4,

m is an integer of 1 or 2,

R ₁ And R ₂ is Each independently is an alkenyl group of C ₁ -C ₆ alkyl group or a C ₁ -C _6,

R ₃ is hydrogen or a methyl group,

X is halogen.

On the other hand, the present invention relates to an electrolyte composition for a lithium secondary battery comprising an imidazolium-based amphoteric ion, a lithium salt, and an organic solvent in which the ether group and sulfonate group represented by Chemical Formula 1 are substituted.

The amphoteric ion represented by Formula 1 is preferably 1 to 15% by weight, more preferably 1 to 5% by weight based on the total weight of the electrolyte composition.

Examples of the lithium salts include lithium salts commonly used in lithium secondary batteries, such as lithium nitrate, lithium perchlorate, lithium acetate, lithium trifluoroacetate, lithium triplate, and lithium bis (trifluoromethanesulfonyl). Imides, lithiumbis (perfluoroethanesulfonyl) imide, lithiumtetrafluoroborate or lithium hexafluorophosphate may be used. The content of the lithium salt is preferably 5 to 30% by weight, more preferably 10 to 20% by weight based on the total weight of the electrolyte composition.

As the organic solvent, organic solvents commonly used in lithium secondary batteries, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl acetate, acetone, acetonitrile, gamma-butyrolactone, tetrahydrofuran, 1,4 -Dioxane, 2-methyltetrahydrofuran, dimethylsulfoxide, sulfolane, 1-methylpyrrolidone, N, N-dimethylformamide, dimethoxyethane, diglyme, tree Any one or a mixture of two or more selected from the group consisting of triglyme and tetraglyme can be used. The content of the organic solvent is preferably 50 to 95% by weight based on the total weight of the electrolyte composition.

The electrolyte composition of the present invention may further include an ionic liquid together with the zwitterion ion, the lithium salt, and the organic solvent represented by Chemical Formula 1.

The ionic liquid is at least one selected from the group consisting of ionic liquids commonly used in lithium secondary batteries, for example, pyrrolidinium, imidazolium, piperidinium, pyridinium, ammonium and morpholinium Can be used. The content of the ionic liquid is preferably 10 to 50% by weight based on the total weight of the electrolyte composition.

In addition, the electrolyte composition of the present invention may further include various additives such as an adhesion improving agent, a filler, etc. in order to improve the mechanical strength of the electrolyte and the interface performance with the electrode.

On the other hand, the present invention relates to a lithium secondary battery comprising the electrolyte composition.

The imidazolium-based amphoteric ion in which the ether group and the sulfonate group are substituted according to the present invention has high thermal and electrochemical stability, and the electrolyte composition for a lithium secondary battery containing the additive as an additive is more effective than the conventional High electrochemical stability and improved charge / discharge performance.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, it is obvious to those skilled in the art that the scope of the present invention is not limited to these examples.

Example  1: 2- Hydroxymethyl -One- Methylimidazole  Produce

In a stainless autoclave, 15.0 g (0.183 mol) of 1-methylimidazole and 9.0 g (0.3 mol) of paraformaldehyde were added together with 50 mL of acetonitrile and reacted at 120 ^° C. for 12 hours to obtain a yellow liquid. The white solid obtained by removing the reaction solvent under reduced pressure was dissolved in ethanol and recrystallized at low temperature (yield 75%).

¹ H NMR (400 MHz, DMSO- d ₆ , 25 ^o C): δ (ppm) = 7.06 (d, 1H, CHN), 7.50 (d, 1H, CHN), 5.25 (s, 1H, OH), 4.46 (d, 2H, CH ₂ O), 3.64 (s, 3H, CH ₃ ).

Example  2: 2- Hydroxyethyl -One- Methylimidazole  Produce

In a stainless autoclave, 8.79 g (0.09 mole) of 1,2-dimethylimidazole and 9.0 g (0.3 mole) of paraformaldehyde were added together with 50 mL of acetonitrile / DMSO (4/1) mixture, and 12 at 120 ^o C. The reaction was carried out for a time to obtain a yellow liquid. The reaction solvent was removed under reduced pressure, and the white solid obtained was dissolved in THF and recrystallized at low temperature (yield 60%).

¹ H NMR (400 MHz, DMSO- d ₆ , 25 ^o C): δ (ppm) = 6.84 (d, 1H, CHN), 6.73 (d, 1H, CHN), 3.96 (t, 2H, CH ₂ O) , 3.80 (s, 1H, OH), 3.50 (s, 3H, CH ₃ ), 2.76 (t, 2H, CH ₂ C).

Example  3: 1-butyl-2- Of hydroxymethylimidazole  Produce

15.14 g (0.12 mol) of 1-butylimidazole and 6.0 g (0.2 mol) of paraformaldehyde were added together with 50 mL of DMSO in a stainless autoclave, and reacted at 120 ^° C. for 12 hours to obtain a yellow liquid. The reaction solvent was removed under reduced pressure and left at low temperature to yield a white solid (yield 83%).

¹ H NMR (400 MHz, CDCl ₃ , 25 ^o C): δ (ppm) = 6.70 (d, 1H, CHN), 6.80 (d, 1H, CHN), 4.60 (s, 2H, CH ₂ O), 4.00 (t, 2H, CCH ₂ O), 1.80 (q, 2H, CH ₂ ), 1.40 (q, 2H, CH ₂ ), 0.90 (t, 2H, CH ₃ ).

Example  4: 2- Hydroxymethyl -One- Vinylimidazole  Produce

In a stainless autoclave, 17.22 g (0.18 mol) of 1-vinylimidazole and 9.0 g (0.3 mol) of paraformaldehyde were added together with 50 mL of acetonitrile and reacted at 120 ^° C. for 12 hours to obtain a yellow liquid. The white solid obtained by removing the reaction solvent under reduced pressure was dissolved in THF and recrystallized at low temperature (yield 53%).

¹ H NMR (400 MHz, CDCl ₃ , 25 ^o C): δ (ppm) = 7.62 (d, 1H, CHN), 7.26 (m, 1H, NCH), 6.88 (d, 1H, CHN), 5.40 (m , 2H, CCH ₂ ), 4.89 (t, 1H, OH), 4.53 (s, 2H, CH ₂ O).

Example  5: 2- Butoxymethyl -One- Methylimidazole  Produce

Put a solution of 1.5 mol NaOH in 60 mL of water into a flask, 6.73 g (0.06 mol) of 1-methyl-2-hydroxymethylimidazole obtained in Example 1 was added and stirred at 80 ^o C for 1 hour. It was. 0.19 g (0.0006 mol) of Bu ₄ NBr was added to the reaction mixture, and 8.22 g (0.06 mol) of bromobutane was slowly added dropwise, followed by reaction at 80 ^° C. for 8 hours. The organic layer was separated, washed with water, dried with MgSO ₄ , and dried under reduced pressure to obtain a brown liquid (yield 65%).

¹ H NMR (400 MHz, DMSO- d ₆ , 25 ^o C): δ (ppm) = 7.1 (s, 1H, CHN), 6.7 (s, 1H, CHN), 4.4 (s, 2H, NCH ₂ O) , 3.6 (s, 3H, NCH ₃ ), 3.3 (m, 2H, OCH ₂ ), 1.4 (m, 2H, CH ₂ ), 1.3 (m, 2H, CH ₂ ), 1.2 (m, 2H, CH ₂ ) .

Example  6: 2- Butoxymethyl -One- Butylimidazole  Produce

A solution of 1.5 mol of NaOH in 60 mL of water was added to a flask, and 9.25 g (0.06 mol) of 1-butyl-2-hydroxymethylimidazole obtained in Example 3 was added thereto, followed by stirring at 80 ^° C. for 1 hour. It was. 0.19 g (0.0006 mol) of Bu ₄ NBr was added to the reaction mixture, and 8.22 g (0.06 mol) of bromobutane was slowly added dropwise, followed by reaction at 80 ^° C. for 8 hours. The organic layer was separated, washed with water, dried with MgSO ₄ , and dried under reduced pressure to obtain a brown liquid (yield 60%).

¹ H NMR (400 MHz, DMSO- d ₆ , 25 ^o C): δ (ppm) = 7.1 (d, 1H, CHN), 6.8 (d, 1H, CHN), 4.4 (s, 2H, CH ₂ O) , 3.9 (t, 2H, NCH ₂ ), 3.3 (t, 2H, OCH ₂ ), 1.7 (m, 2H, CH ₂ ), 1.5 (m, 2H, CH ₂ ), 1.3 (m, 4H, CH ₂ ) , 0.9 (m, 6H, CH ₃ ).

Example  7: 2- Butoxymethyl -One- Methylimidazolium -3- Of propanesulfonate  Produce

20 mL of acetone and 1.7 g (0.01 mol) of 2-butoxymethyl-1-methylimidazole obtained in Example 5 were added to a round bottom flask, and 1.5 g (0.012 mol) of 1,3-propanesultone was added thereto. After refluxing for 12 hours. The reaction mixture was filtered and washed several times with acetone to give 2-butoxymethyl-1-methylimidazolium-3-propanesulfonate as a white solid (yield 83%).

¹ H NMR (400 MHz, DMSO- d ₆ , 25 ^o C): δ (ppm) = 7.8 (d, 1H, CHN), 7.7 (d, 1H, CHN), 4.8 (s, 2H, NCH ₂ O) , 4.3 (m, 2H, NCH ₂ ), 3.8 (s, 3H, NCH ₃ ), 3.5 (m, 2H, OCH ₂ ), 2.4 (m, 2H, SCH ₂ ), 2.0 (m, 2H, CH ₂ ) , 1.5 (m, 2H, CH ₂ ), 1.3 (m, 2H, CH ₂ ), 1.3 (m, 3H, CH ₃ ).

Example  8: 2- Butoxymethyl -One- Butyl imidazolium -3- Of propanesulfonate  Produce

20 mL of acetone and 2.1 g (0.01 mol) of 2-butoxymethyl-1-butylimidazole obtained in Example 6 were added to a round bottom flask, and 1.5 g (0.012 mol) of 1,3-propanesultone was added thereto. After refluxing for 12 hours. The reaction mixture was filtered and washed several times with acetone to give 2-butoxymethyl-1-butylimidazolium-3-propanesulfonate as a white solid (yield 80%).

¹ H NMR (400 MHz, DMSO- d ₆ , 25 ^o C): δ (ppm) = 7.9 (d, 2H, CHN), 4.9 (s, 2H, CH ₂ O), 4.4 (t, 2H, NCH ₂ ), 4.2 (t, 2H, NCH ₂ ), 3.6 (t, 2H, OCH ₂ ), 2.5 (m, 2H, CH ₂ ), 2.1 (t, 2H, CH ₂ S), 1.8 (m, 2H, CH ₂ ), 1.6 (m, 2H, CH ₂ ), 1.3 (m, 4H, CH ₂ ), 0.9 (m, 6H, CH ₃ ).

Comparative example  1: 1,2- Dimethylimidazolium -3- Of propanesulfonate  Produce

20 mL of acetone and 5.77 g (0.06 mol) of 1,2-dimethylimidazole were added to a round bottom flask, and 1,3-propanesultone 7.33 g (0.06 mol) was added thereto, followed by reflux for 12 hours. The reaction mixture was filtered and washed several times with acetone to give 1,2-dimethylimidazolium-3-propanesulfonate as a white solid (yield 91%).

¹ H NMR (400 MHz, D ₂ O, 25 ^o C): δ (ppm) = 7.41 (s, 1H, CHN), 7.34 (s, 1H, CHN), 4.29 (t, 2H, CH ₂ N), 3.78 (s, 3H, NCH ₃ ), 2.95 (t, 2H, SCH ₂ ), 2.61 (s, 3H, CH ₃ ), 2.26 (m, 2H, CH ₂ ).

Comparative example  2: 1- Methoxyethyl -2- Methylimidazolium -3- Of propanesulfonate  Produce

A solution of 8.2 g (0.1 mol) of 2-methylimidazole in 50 mL of anhydrous DMF containing 2.6 g (0.11 mol) of NaH was slowly added dropwise at room temperature to the reaction, followed by reaction at 60 ° C. for 1 hour. After the reaction, excess NaH was filtered off and 9.4 g (0.1 mol) of 2-chloroethyl methyl ether was slowly added dropwise to the brown solution obtained over 30 minutes. After 3 hours, NaCl precipitate was removed by filtration, and 12.8 g (0.105 mol) of 1,3-propanesultone was added thereto, and reacted at 80 ° C. for 12 hours. After the reaction was completed, the solid product obtained by drying under reduced pressure was washed with acetone and recrystallized from methanol to obtain 1-methoxyethyl-2-methylimidazolium-3-propanesulfonate as a white solid (yield 82%). .

¹ H NMR (400 MHz, D ₂ O, 25 ^o C): δ (ppm) = 7.42 (d, 2H, CHN), 3.81 (t, 2H, CH ₂ ), 3.34 (s, 3H, CH ₃ ), 3.30 (m, 4H, CH ₂ ), 2.93 (t, 2H, CH ₂ ), 2.62 (s, 3H, CH ₃ ), 2.13 (m, 2H, CH ₂ ).

Experimental Example  1: Electrochemical stability measurement

2-butoxymethyl-1-methylimidazolium-3-propanesulfonate prepared in Example 7, 1,2-dimethylimidazolium-3-propanesulfonate prepared in Comparative Example 1 and the comparison Ethylene carbonate (EC): Propylene carbonate (PC): Dimethyl carbonate in which LiPF ₆ was dissolved in the 1-methoxyethyl-2-methylimidazolium-3-propanesulfonate prepared in Example 2 at 1 M concentration, respectively. 1 to 5% by weight in a 1: 1: 1 mixed solution of DMC), and the cyclic voltammetry was measured by an electrochemical analyzer (Electrochemical Analyzer; Model 660A, CH Instruments). In this case, a glassy carbon electrode was used as the electrode, a platinum wire was used as the counter electrode, and a silver wire was used as the reference electrode. The measurement speed was 10 mVS- ¹ .

As a result, as shown in FIG. 1, when the ether group was substituted at the C-2 position, it was confirmed that the electrochemical stability was significantly improved from -2.5 V to 2.5 V (vs. Ag).

Experimental Example  2: Charge and discharge  Performance measurement

2-butoxymethyl-1-methylimidazolium-3-propanesulfonate prepared in Example 7 and 1,2-dimethylimidazolium-3-propanesulfonate prepared in Comparative Example 1 were each 1 An electrolyte was prepared by dissolving 1 to 5% by weight in a 1: 1: 1 mixed solution of ethylene carbonate (EC): propylene carbonate (PC): dimethyl carbonate (DMC) in which LiPF ₆ was dissolved at a M concentration. The lithium _secondary battery was fabricated in a dry room using LiCoO ₂ as a positive electrode and a carbon electrode as a negative electrode, and the charge and discharge performance of the lithium secondary battery manufactured using a battery cycler (Cycler; One Artec, WBC 3000) was measured. It was.

As a result, as shown in Fig. 2, repeated charging and discharging was performed at 1/2 C for 120 or more times. As a result, imidazolium sulfonated amphoteric ions having an ether group introduced at the C-2 position according to the present invention. When used as an additive was confirmed to show a significantly improved charge and discharge performance.

1 shows (a) a model electrolyte without addition of zwitterion ions, (b) 1,2-dimethylimidazolium-3-propanesulfonate, and (c) 1-methoxyethyl-2-methyl It is a graph showing the electrochemical stability of the electrolyte to which midazolium-3-propanesulfonate and (d) 2-butoxymethyl-1-methylimidazolium-3-propanesulfonate were added, respectively.

FIG. 2 shows (a) a lithium secondary battery prepared without adding amphoteric ions, (b) 2.25 wt% 2-butoxymethyl-1-methylimidazolium-3-propanesulfonate, (c) 4.5 wt % 2-butoxymethyl-1-methylimidazolium-3-propanesulfonate and (d) 2.25% by weight of 1,2-dimethylimidazolium-3-propanesulfonate as additives respectively A graph showing the charge and discharge performance of a lithium secondary battery.

Claims (11)

Imidazolium-based amphoteric ions represented by Formula 1 below: [Formula 1]

Where n is an integer of 3 or 4, m is an integer of 1 or 2, R ₁ And R ₂ is Each independently is an alkenyl group of C ₁ -C ₆ alkyl group or a C ₁ -C _6. The method of claim 1, n is an integer of 3 or 4, m is an integer of 1 or 2, R ₁ and R ₂ Imidazolium-based amphoteric ions each independently being a C ₁ -C ₆ alkyl group. The method of claim 1, n is 3, m is 1, R ₁ is methyl, ethyl, propyl or butyl, R ₂ is butyl imidazolium-based amphoteric ion. The method of claim 1, n is 3, m is 1, R ₁ is methyl, R ₂ is butyl imidazolium-based amphoteric ion. (i) As shown in Scheme 1, imidazole and paraformaldehyde are reacted to obtain 2-hydroxyalkylimidazole, which is reacted with alkyl halide or alkenyl halide in the presence of a base to convert ether group to imidazole. Obtaining; And (ii) Formula 1 of claim 1 comprising reacting the imidazole substituted with the ether group obtained in step (i) with 1,3-propanesultone or 1,4-butanesultone as in Scheme 2 below Method for producing an imidazolium-based amphoteric ion represented by: Scheme 1

Scheme 2

Where n is an integer of 3 or 4, m is an integer of 1 or 2, R ₁ and R ₂ Each independently is an alkenyl group of C ₁ -C ₆ alkyl group or a C ₁ -C _6, R ₃ is hydrogen or a methyl group, X is halogen. An electrolyte composition for a lithium secondary battery, comprising an imidazolium-based amphoteric ion, a lithium salt, and an organic solvent of claim 1. The lithium salt according to claim 6, wherein the lithium salt is lithium nitrate, lithium perchlorate, lithium acetate, lithium trifluoroacetate, lithium triplate, lithium bis (trifluoromethanesulfonyl) imide, lithium bis (perfluoroethanesulfur) Phenyl) imide, lithium tetrafluoroborate or lithium hexafluoro phosphate electrolyte composition for a lithium secondary battery. The organic solvent of claim 6, wherein the organic solvent is ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl acetate, acetone, acetonitrile, gamma-butyrolactone, tetrahydrofuran, 1,4-dioxane, 2-methyltetrahydrofuran, Any one or a mixture of two or more selected from the group consisting of dimethyl sulfoxide, sulfolane, 1-methylpyrrolidone, N, N-dimethylformamide, dimethoxyethane, diglyme, triglyme and tetraglyme An electrolyte composition for a lithium secondary battery, characterized in that. The electrolyte composition for a lithium secondary battery according to any one of claims 6 to 8, further comprising an ionic liquid. The electrolyte for a lithium secondary battery according to claim 9, wherein the ionic liquid comprises at least one selected from the group consisting of pyrrolidinium, imidazolium, piperidinium, pyridinium, ammonium and morpholinium. Composition. A lithium secondary battery comprising the electrolyte composition for a lithium secondary battery of claim 6.

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