KR20120096439A - Composition for preparing anode for lithium secondary battery and lithium secondary battery using the same - Google Patents

Abstract

PURPOSE: A composition for forming electrode is provided to improve dispersity of additives, while minimizing a using amount of the additives, and to maintain formation effect of a solid electrolyte interface membrane by comprising a solid electrolyte interface membrane forming agent. CONSTITUTION: A composition for forming electrode comprises a negative electrode active material, binder, solvent, and a solid electrolyte interface membrane forming agent. The solid electrolyte interface membrane forming agent is one or a mixture of two kinds selected from vinylene carbonate, fluoroethylene, carbonate, vinylethylene, carbonate, cyclic sulfite, saturated sulfone, unsaturated sultone, and non-cyclic sulfone. The cyclic sulfite is in chemical formula 1. In chemical formula 1, R^3-R^6 is respectively halogen, C1-6 alkyl group, or C1-6 haloalkyl group, and n is an integer form 1-3.

Description

A composition for forming a negative electrode for a lithium secondary battery and a lithium secondary battery manufactured using the same TECHNICAL FIELD

The present invention relates to a composition for forming a negative electrode for a lithium secondary battery containing an additive and maximizing the effect of use of the additive, and a lithium secondary battery produced using the same.

Recently, interest in energy storage technology is increasing. As the field of application extends to the energy of mobile phones, camcorders, notebook PCs, and even electric vehicles, the demand for high energy density of batteries used as power sources for such electronic devices is increasing. Lithium secondary batteries are the ones that can best meet these demands, and researches on them are actively under way.

Among the secondary batteries currently applied, lithium secondary batteries developed in the early 1990's include lithium salts dissolved in an appropriate amount of a negative electrode such as a carbon material capable of occluding and releasing lithium ions, a positive electrode made of lithium-containing oxide, and a mixed organic solvent. It consists of a nonaqueous electrolyte.

The average discharge voltage of a typical lithium secondary battery is about 3.6 to 3.7 V, which is higher than that of other alkali batteries, nickel-cadmium batteries, and the like. In order to achieve such a high driving voltage, an electrochemically stable electrolyte composition is required at a charge and discharge voltage range of about 0 to 4.2 V. For this purpose, a mixed solvent in which cyclic carbonate compounds such as ethylene carbonate and propylene carbonate and linear carbonate compounds such as dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate are appropriately mixed is used as a solvent of the electrolyte solution. As the solute of the electrolyte, lithium salts such as LiPF ₆ , LiBF ₄ , and LiClO ₄ are usually used, and these act as a source of lithium ions in the battery to enable operation of the lithium battery.

During the initial charging of the lithium secondary battery, lithium ions derived from the positive electrode active material such as lithium metal oxide move to the negative electrode active material such as graphite and are inserted between the layers of the negative electrode active material. At this time, since lithium is highly reactive, the electrolyte and the carbon constituting the negative electrode active material react on the surface of the negative electrode active material such as graphite to generate compounds such as Li ₂ CO ₃ , Li ₂ O, and LiOH. These compounds form a kind of SEI (Solid Electrolyte Interface) film on the surface of an anode active material such as graphite.

The SEI membrane acts as an ion tunnel, allowing only lithium ions to pass through. The SEI membrane is an effect of this ion tunnel, which prevents the breakdown of the negative electrode structure by intercalation of organic solvent molecules having a large molecular weight moving with lithium ions in the electrolyte between the layers of the negative electrode active material. Therefore, by preventing contact between the electrolyte solution and the negative electrode active material, decomposition of the electrolyte solution does not occur, and the amount of lithium ions in the electrolyte solution is reversibly maintained to maintain stable charge and discharge.

However, in the thin rectangular battery, there is a problem that the battery thickness expands during charging due to gases such as CO, CO ₂ , CH ₄ , and C ₂ H ₆ generated from decomposition of the carbonate solvent during the above-described SEI film formation reaction. do. In addition, as time elapses at high temperature in a full charge state, the SEI film is gradually decayed by increased electrochemical energy and thermal energy, so that side reactions in which the exposed cathode surface reacts with the surrounding electrolyte continuously occur. In this case, the internal pressure of the battery increases due to the continuous gas generation. As a result, in the case of the square battery and the pouch battery, the thickness of the battery increases, causing problems in electronic devices such as mobile phones and notebook computers. That is, high temperature leaving safety is bad.

In order to suppress the increase in the internal pressure of the battery, research has been conducted to change the aspect of the SEI film formation reaction by adding an additive to the electrolyte, and various additives for SEI film formation have been introduced.

However, when the additive is added to the electrolyte, the additive is distributed not only in the negative electrode to which the additive works but also in the positive electrode and the separator.

Accordingly, an object of the present invention is to provide a composition for forming a negative electrode for a lithium secondary battery that can maximize the effect of the additive while minimizing the amount of the additive, and to provide a lithium secondary battery manufactured using the same.

In order to solve the above problems, the present invention comprises a negative electrode active material, a binder, a solvent, and an SEI film forming agent, wherein the SEI film forming agent is vinylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated Provided is a composition for forming a negative electrode for a lithium secondary battery, which is any one selected from the group consisting of sultone, unsaturated sultone, and acyclic sulfone, or a mixture of two or more thereof.

The present invention can maintain the effect of forming the SEI film by increasing the dispersion of the additive while minimizing the amount of the additive by adding the additive for forming the SEI film, which is conventionally added to the electrolyte, to the composition for forming the cathode.

The cyclic sulfite may be represented by, for example, the following Formula 1:

In Formula 1, R ³ to R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 1-3.

The saturated sultone may be represented by, for example, the following Formula 2:

In Formula 2, R ⁷ to R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 0-3.

The unsaturated sultone may be represented by, for example, the following Formula 3:

In Formula 3, R ¹³ to R ¹⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 0-3.

The acyclic sulfone may be represented by the following Formula 4, for example:

In Formula 4, R ¹⁷ and R ¹⁸ are each independently C ₁ ~ C ₆ Alkyl group, C ₁ ~ C ₆ Haloalkyl group, C ₂ ~ C ₆ Alkenyl group, C ₂ ~ C ₆ Haloalkenyl group, C ₆ -C ₁₈ aryl group, or C ₆ -C ₁₈ haloaryl group.

The SEI film forming agent according to the present invention may be included in the composition for forming a negative electrode at 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the negative electrode active material.

Optionally, the composition for forming a negative electrode for a lithium secondary battery of the present invention may further include a carbonate, an alcohol, or a mixture thereof as an auxiliary solvent in order to increase the solubility of the SEI film forming agent.

The composition for forming a negative electrode for a lithium secondary battery of the present invention may be applied to at least one surface of a negative electrode current collector and then dried to prepare a negative electrode. The prepared negative electrode may be formed with an SEI film without adding an SEI film forming agent to an electrolyte. Therefore, it can be usefully used in a lithium secondary battery.

The composition for forming a negative electrode for a lithium secondary battery of the present invention may contain a SEI film forming agent, thereby significantly reducing the content of the SEI film forming agent, which has been added more than necessary to the conventional electrolyte solution. In addition, since the SEI film forming agent may be present not only around the negative electrode active material particles on the electrode surface but also around the negative electrode active material particles therein, the use effect of the additive may be maximized.

Therefore, the lithium secondary battery can be manufactured more economically than before, and it can be prevented from being added as an excess to the conventional electrolyte and remaining as impurities or causing side reactions in the battery.

1 is a graph showing the life characteristics of the lithium secondary battery prepared in Examples and Comparative Examples.

Hereinafter, the present invention will be described in detail. 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 negative electrode formation for lithium secondary batteries of this invention contains a negative electrode active material, a binder, a solvent, and an SEI film forming agent.

As described above, the SEI film is formed on the surface of the negative electrode active material. However, conventionally, since the SEI film-forming agent was added to the electrolyte and injected into the battery, it was impossible to distribute the SEI film-forming agent only around the negative electrode active material as a target. Therefore, inevitably, the SEI film-forming agent has to be used in excess, and the SEI film-forming agent remaining in the electrolyte solution without forming the SEI film is distributed to the separator, the anode, and the like, which causes impurities or side reactions.

However, the present invention solves the above problems by containing the SEI film-forming agent in the composition for forming the negative electrode. By adding the SEI film-forming agent to the composition for forming a negative electrode, the SEI film-forming agent can be placed only on or near the surface of the negative electrode active material, and the amount of use of the SEI film-forming agent can be greatly reduced than before. Therefore, the manufacturing cost of the battery can be reduced as compared with the related art, and the above problems due to the remaining SEI film forming agent can be solved.

In the present invention, the SEI film forming agent is any one or a mixture of two or more selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone. .

In the SEI film forming agent according to the present invention, the cyclic sulfite may be represented by, for example, the following Chemical Formula 1:

[Formula 1]

In Formula 1, R ³ to R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 1-3.

Non-limiting examples of the cyclic sulfite of Formula 1, ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite , 4,5-dimethyl propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite and 1,3-butylene glycol sulfite can do. In addition, these compounds can be used individually or in mixture of 2 or more types.

In the SEI film forming agent according to the present invention, the saturated sultone may be represented by, for example, the following Chemical Formula 2:

[Formula 2]

In Formula 2, R ⁷ to R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 0-3.

Non-limiting examples of the saturated sultone of Formula 2 may include 1,3-propane sultone and 1,4-butane sultone, but is not limited thereto. In addition, these compounds can be used individually or in mixture of 2 or more types.

In the SEI film forming agent according to the present invention, the unsaturated sultone may be represented by, for example, the following Formula 3:

(3)

In Formula 3, R ¹³ to R ¹⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 0-3.

Non-limiting examples of the unsaturated sultone of Formula 3 may include ethene sultone, 1,3-propene sultone, 1,4-butene sultone, 1-methyl-1,3-propene sultone. In addition, these compounds can be used individually or in mixture of 2 or more types.

In the SEI film forming agent according to the present invention, the acyclic sulfone may be represented by the following Chemical Formula 4, for example:

[Formula 4]

In Formula 4, R ¹⁷ and R ¹⁸ are each independently C ₁ ~ C ₆ Alkyl group, C ₁ ~ C ₆ Haloalkyl group, C ₂ ~ C ₆ Alkenyl group, C ₂ ~ C ₆ Haloalkenyl group, C ₆ -C ₁₈ aryl group, or C ₆ -C ₁₈ haloaryl group.

Non-limiting examples of the sulfone of Formula 4 may include divinyl sulfone, dimethyl sulfone, diethyl sulfone, methylethyl sulfone, methylvinyl sulfone. In addition, these compounds can be used individually or in mixture of 2 or more types.

The content of the SEI film forming agent according to the present invention may be variously determined according to the type of the specific SEI film forming agent used, the type of the negative electrode active material, the conditions of use of the battery, and the like. For example, in order to effectively form the SEI film while minimizing the remaining amount inside the battery, 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of the negative electrode active material, may be included in the composition for forming a negative electrode, but is not limited thereto. It is not.

As the negative electrode active material used in the composition for forming a negative electrode for a lithium secondary battery of the present invention, a carbon material, lithium, a lithium alloy, silicon, a silicon alloy, tin, a tin alloy, etc., in which lithium ions may be stored and released, may be used. Also possible are metal oxides such as TiO ₂ and SnO ₂ with a potential of less than 2V for lithium. Preferably, a carbon material may be used, and as the carbon material, both low crystalline carbon and high crystalline carbon may be used. Soft crystalline carbon and hard carbon are typical low crystalline carbon, and high crystalline carbon is natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch-based carbon fiber. High temperature calcined carbon such as (mesophase pitch based carbon fiber), meso-carbon microbeads, Mesophase pitches and petroleum or coal tar pitch derived cokes.

As the binder used in the composition for forming a negative electrode for a lithium secondary battery of the present invention, a binder commonly used may be used without limitation. For example, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, SBR Various types of binder polymers, such as (styrene butadiene rubber) and CMC (carboxymethyl cellulose), may be used.

The solvent used in the composition for forming a negative electrode for a lithium secondary battery of the present invention may be used without limitation as long as it is used as a solvent for the composition for forming a negative electrode in the art. For example, n-methylpyrrolidone, dimethyl sulfoxide, cresol, water, etc. may be used alone or in combination of two or more thereof, but is not limited thereto.

Optionally, the composition for forming a negative electrode for a lithium secondary battery of the present invention may further include a carbonate, an alcohol, or a mixture thereof as an auxiliary solvent. The cosolvents are used for the purpose of controlling the polarity to increase the solubility of the SEI film forming agent.

Examples of the carbonate that can be used as the cosolvent include linear carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; Cyclic carbonates such as ethylene carbonate and propylene carbonate; And mixtures thereof, and the like may include, but is not limited to, isopropyl alcohol, isobutyl alcohol, and the like.

The composition for forming a negative electrode of the present invention may be applied to at least one surface of the negative electrode current collector and dried to be used as a negative electrode of a lithium secondary battery. At this time, the SEI film-forming agent is located in the vicinity of the surface of the negative electrode active material or the active material. Therefore, when the electrolyte is injected during battery assembly, the SEI film may be formed on the surface of the negative electrode active material by reacting with the electrolyte reaching the negative electrode.

The lithium secondary battery according to the present invention is manufactured as a lithium secondary battery by injecting a nonaqueous electrolyte into an electrode structure consisting of the prepared negative electrode, the positive electrode and the separator interposed between the positive electrode and the negative electrode. In addition to the negative electrode according to the present invention, the positive electrode, the separator, and the non-aqueous electrolyte may be used all of those conventionally used in manufacturing a lithium secondary battery.

The nonaqueous electrolyte according to the present invention includes an ionizable lithium salt and an organic solvent.

The lithium salt contained as an electrolyte in a non-aqueous liquid electrolyte of the present invention can be used without limitation, those which are commonly used in a lithium secondary battery electrolyte, such 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 (CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

As the organic solvent included in the nonaqueous electrolyte of the present invention described above, those conventionally used in the lithium secondary battery electrolyte may be used without limitation, and for example, ethers, esters, amides, linear carbonates, cyclic carbonates, and the like may be used alone or independently. It can mix and use 2 or more types.

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, 2,3-pentylene carbonate, vinylene carbonate, and any one selected from the group consisting of halides thereof or mixtures of two or more thereof. Specific examples of the linear carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate. Any one selected or a mixture of two or more thereof may be representatively used, but is not limited thereto.

In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates among the carbonate-based organic solvents, are highly viscous organic solvents, and thus may be preferably used because they dissociate lithium salts in the electrolyte well, such as dimethyl carbonate and diethyl carbonate. When the same low viscosity, low dielectric constant linear carbonate is mixed and used in an appropriate ratio, an electrolyte having high electrical conductivity can be made, and thus it can be used more preferably.

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

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

In addition, in the positive electrode, the negative electrode, and the separator constituting the electrode structure, in addition to the negative electrode prepared according to the present invention, both the positive electrode and the separator that is conventionally used in the manufacture of a lithium secondary battery can be used.

As a specific example, a lithium-containing transition metal oxide may be preferably used as the cathode active material. For example, Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), and Li _x MnO ₂ (0.5 <x <1.3), Li _x Mn ₂ O ₄ (0.5 <x <1.3), Li _x (Ni _a Co _b Mn _c ) O ₂ (0.5 <x <1.3, 0 <a <1, 0 < b <1, 0 <c <1, a + b + c = 1), Li _x Ni _1-y Co _y O ₂ (0.5 <x <1.3, 0 <y <1), Li _x Co _1-y Mn _y O ₂ (0.5 <x <1.3, 0 ≦ y <1), Li _x Ni _1-y Mn _y O ₂ (0.5 <x <1.3, O ≦ y <1), Li _x (Ni _a Co _b Mn _c ) O ₄ (0.5 <x <1.3, 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _2-z Ni _z O ₄ (0.5 < x <1.3, 0 <z <2), Li _x Mn _2-z Co _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x CoPO ₄ (0.5 <x <1.3) and Li _x FePO ₄ (0.5 <x <1.3) may be used any one selected from the group consisting of or a mixture of two or more thereof, and the lithium-containing transition metal oxide may be coated with a metal or metal oxide such as aluminum (Al). . In addition to the lithium-containing transition metal oxide, sulfide, selenide, halide, and the like may also be used.

In the composition for forming an anode, the binder used in the cathode may be used in the same manner.

In addition, as the separator, conventional porous polymer films conventionally used as separators, for example, polyolefins such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer, etc. The porous polymer film made of the polymer may be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used. It is not.

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, square, pouch type, or coin type using a can.

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

Example

<Production of Composition for Cathode Formation>

96.0 parts by weight of natural graphite, 1.0 part by weight of carboxymethylcellulose, 2.0 parts by weight of styrene-butadiene rubber, and 1.0 part by weight of conductive carbon were mixed sequentially with water in a mortar, followed by stirring sufficiently. To this mixture, vinylene carbonate was added in an amount of 2.0% by weight, that is, 1.92 parts by weight of natural graphite as a negative electrode active material, and then stirred again to prepare a composition for forming a uniform negative electrode.

<Production of Anode for Lithium Secondary Battery>

The prepared negative electrode-forming composition was coated with a thickness of 250 μm on a copper foil having a thickness of 10 μm, and dried in an oven at about 120 ° C. for about 1 hour to prepare a negative electrode.

<Production of Lithium Secondary Battery>

A coin cell of CR2016 standard was manufactured by using lithium as a positive electrode in the prepared negative electrode, and a separator was used as a polyethylene porous film having a thickness of 20 μm. As the electrolyte, ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 2, and LiPF6 1M was dissolved and used to prepare a lithium secondary battery.

Comparative example

A lithium secondary battery was manufactured in the same manner as in Example, except that vinylene carbonate was not added at the time of manufacturing the negative electrode, and vinylene carbonate corresponding to 2.0 wt% of the natural graphite, the negative electrode active material, was added to the electrolyte. .

<Charge / Discharge Cycle Performance Evaluation>

For the coin cells prepared in the above Examples and Comparative Examples, the life characteristics were measured as a percentage of the initial capacity for each cycle under the conditions of 1.0C charge and discharge cycle, the measurement results are shown in FIG.

Referring to FIG. 1, the results of comparing the performance of the examples in which the vinylene carbonate was added at the same weight ratio with the active material and the comparative example added into the electrolyte, and the charge / discharge cycles were directly injected into the active material showed better results. It can be seen that.

Claims (10)

Anode active material; bookbinder; menstruum; And an SEI film former,
The SEI film forming agent is a lithium secondary which is any one selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone or a mixture of two or more thereof. A composition for forming a negative electrode for a battery. The method of claim 1,
The cyclic sulfite is a composition for forming a negative electrode for a lithium secondary battery, characterized in that the cyclic sulfite represented by the formula (1):
[Formula 1]

In Formula 1, R ³ to R ⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 1-3. The method of claim 1,
The saturated sultone is a composition for forming a negative electrode for a lithium secondary battery, characterized in that the saturated sultone represented by the formula (2):
(2)

In Formula 2, R ⁷ to R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 0-3. The method of claim 1,
The unsaturated sultone is a composition for forming a negative electrode for a lithium secondary battery, characterized in that the unsaturated sultone represented by the formula (3).
(3)

In Formula 3, R ¹³ to R ¹⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group of C ₁ ~ C _6, or a haloalkyl group of C ₁ ~ C _6, n is an integer from 0-3. The method of claim 1,
The acyclic sulfone is a composition for forming a negative electrode for a lithium secondary battery, characterized in that the acyclic sulfone represented by the formula (4).
[Chemical Formula 4]

In Formula 4, R ¹⁷ and R ¹⁸ are each independently C ₁ ~ C ₆ Alkyl group, C ₁ ~ C ₆ Haloalkyl group, C ₂ ~ C ₆ Alkenyl group, C ₂ ~ C ₆ Haloalkenyl group, C ₆ ~ C ₁₈ aryl groups, halo aryl, or C ₆ ~ C ₁₈ of. The method of claim 1,
The SEI film forming agent is 0.1 to 5 parts by weight based on 100 parts by weight of the negative electrode active material, the composition for forming a negative electrode for a lithium secondary battery. The method of claim 1,
A composition for forming a negative electrode for a lithium secondary battery, further comprising carbonate, alcohol, or a mixture thereof as an auxiliary solvent. The method of claim 1,
The negative electrode active material is any one selected from the group consisting of carbon materials, lithium, lithium alloys, silicon, silicon alloys, tin, and tin alloys in which lithium ions can be occluded and released, or a mixture of two or more thereof. A composition for forming a negative electrode for a lithium secondary battery. A negative electrode for a lithium secondary battery having a current collector and a negative electrode active material layer formed by applying and drying the negative electrode forming composition of any one of claims 1 to 8 on at least one surface of the current collector. In a lithium secondary battery comprising a negative electrode, a positive electrode and a nonaqueous electrolyte,
The negative electrode is a lithium secondary battery, characterized in that the negative electrode of claim 9.

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