KR101069471B1 - Non-aqueous electrolyte and secondary battery using the same - Google Patents

Abstract

The present invention uses a sulfonate-based compound having two or more sulfonate groups and at least one of the sulfonate groups substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon as one component of an electrolyte solution. Thus, a denser and more stable SEI film is formed on the surface of the negative electrode, which relates to a secondary battery having improved capacity storage characteristics and lifetime performance of the battery.

The present invention also provides a novel sulfonate compound.

Description

Non-aqueous electrolyte and secondary battery using same {NON-AQUEOUS ELECTROLYTE AND SECONDARY BATTERY USING THE SAME}

The present invention is a non-aqueous electrolyte; And it relates to a secondary battery comprising the same. More specifically, the present invention provides a non-aqueous electrolyte containing a compound capable of improving capacity storage characteristics and lifespan performance of a secondary battery; And it relates to a secondary battery comprising the same.

In recent years, with the trend of miniaturization and weight reduction of electronic devices, miniaturization and weight reduction of batteries serving as power sources are also required. BACKGROUND ART Secondary batteries have been put to practical use as small-sized, light-weight, high-capacitance rechargeable batteries, and are used in portable electronic and communication devices such as small video cameras, mobile phones, and notebook computers.

The secondary battery may be composed of a positive electrode, a negative electrode, a porous separator, and a non-aqueous electrolyte containing an electrolyte salt and an electrolyte solvent.

The non-aqueous electrolyte generally requires the following characteristics with respect to the operation and use of the battery. First, it must be able to sufficiently transfer ions between two electrodes during insertion and desorption of lithium ions from the cathode and anode, and second, it is electrochemically stable at the potential difference between the two electrodes, so that there is little concern about side reactions such as decomposition of electrolyte components. All.

However, conventional electrolyte solvents, such as carbonate-based organic solvents, may decompose on the electrode surface during charge and discharge to cause side reactions in the battery. In addition, an organic solvent such as propylene carbonate (PC) may be co-intercalated between the graphite layers in the carbon-based negative electrode, thereby disrupting the structure of the negative electrode.

On the other hand, it is known that the problem can be solved by a solid electrolyte interface (SEI) film formed on the surface of the negative electrode by electrical reduction of the carbonate-based organic solvent during the initial charging of the battery. However, when the SEI film is formed, lithium ions in the electrolyte are irreversibly involved, resulting in a decrease in battery capacity. In addition, the SEI film is generally not electrochemically or thermally stable, and may easily be collapsed by increased electrochemical energy and thermal energy as charging and discharging proceeds. Therefore, the battery capacity may be reduced due to the continuous regeneration of the SEI film during charging and discharging of the battery, and the lifespan performance of the battery may be reduced.

In addition, side reactions such as decomposition of the electrolyte may occur on the exposed surface of the negative electrode due to the collapse of the SEI film, and a problem may occur that the battery swells or the internal pressure increases due to the generated gas.

In order to solve the above problems, 1,3-propanesultone (Japanese Patent Application No. 1999-339850), 1,3-propenesultone (1,3-propensultone; Japanese Patent Application No. 2001- 151863) has been presented. However, even in the case of the above method, as the cycle continues, the capacity gradually decreases, and the above problems still exist.

The present invention uses a sulfonate-based compound having two or more sulfonate groups and at least one of the sulfonate groups substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon as one component of an electrolyte solution. By forming a denser and more stable SEI film on the surface of the negative electrode, it is intended to improve capacity storage characteristics and life performance of the battery.

The present invention is an electrolyte salt; Electrolyte solvents; And a sulfonate-based compound, wherein the sulfonate-based compound has two or more sulfonate groups, and at least one of the sulfonate groups has a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon. An electrolytic solution characterized by being substituted; And it provides a secondary battery having the electrolyte solution.

In addition, the present invention is formed by the electrical reduction of the sulfonate-based compound having two or more sulfonate groups, at least one of the sulfonate groups substituted with a C ₃ ~ C ₂₀ alkenyl group having a β, γ-unsaturated carbon An electrode on which a solid electrolyte interface (SEI) film is formed on part or all of a surface thereof; And it provides a secondary battery having the electrode.

Furthermore, the present invention provides a compound having a structure of Formula 3 or 4 below.

(3)

In Formula 3, R ₇ is one of hydrogen, C ₁ ~ alkenyl, phenyl (phenyl) in C ₆ alkyl group or a haloalkyl group, C ₂ ~ C ₆ atoms, or benzyl (benzyl) group, R ₈ ~ R ₁₀ At least one is a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the others are independently the same as defined in R ₇ , n is an integer of 1 to 6, m is an integer of 0 to 6 to be.

[Formula 4]

In Formula 4, at least one of R ₁₁ to R ₁₄ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the rest are each independently hydrogen, C ₁ ~ C ₆ alkyl group or haloalkyl group , C ₂ ~ C ₆ Alkenyl group, phenyl (phenyl), and benzyl (benzyl) group selected from the group consisting of, n is an integer of 1-6, m is an integer of 0-6.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention uses a sulfonate-based compound having two or more sulfonate groups and at least one of the sulfonate groups substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon as one component of an electrolyte solution. Thus, a more compact and stable solid electrolyte interface (SEI) film is formed on the cathode surface. This action can be estimated as follows, but is not limited thereto.

In the sulfonate-based compound, lithium ions are coordinated to oxygen of a sulfonate group during electrical reduction, and a bond between sulfur and a substituent of the sulfonate group is interrupted, thereby forming a lithium sulfonate radical (-SO ₃ ^- Li ⁺ ) and a substituent radical. Form. The sulfonate compound of the present invention includes a C ₃ to C ₂₀ alkenyl group (eg, an allyl group) having a β, γ-unsaturated carbon as a substituent of the sulfonate group. Accordingly, in the present invention, the substituent radical (for example, allyl radical) formed above may have a chemically stable resonance structure, which may advantageously act to reduce the sulfonate-based compound. That is, the present invention can exhibit high reactivity in the SEI film formation mechanism.

In addition, since the sulfonate-based compound of the present invention contains two or more sulfonate groups, two or more highly reactive sulfonate radicals are generated during electrical reduction. Therefore, in the present invention, various types of polymerization reactions are performed between the sulfonate radicals and lithium ions or other electrolyte components, thereby forming a polymer SEI film on the surface of the negative electrode.

Due to the above, in the present invention, a denser and more stable SEI film can be formed than the SEI film formed by a conventional carbonate-based organic solvent or a compound containing one sulfonate group. Can be improved. In addition, the SEI film of the present invention contains a large number of polar groups (S, O, etc.), it can exhibit excellent lithium ion conductivity.

The sulfonate compound of the present invention can be used without limitation as long as it has a compound having two or more sulfonate groups and at least one of the sulfonate groups is a compound substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon. Do.

In addition, the C ₃ ~ C ₂₀ alkenyl group having the β, γ-unsaturated carbon preferably has a conjugation (conjugation) structure. In this case, the alkenyl group radicals may have a number of resonance structures and thus may be more chemically stable, thereby reducing the sulfonate compound of the present invention may be more advantageous.

The alkenyl group of C ₃ to C ₂₀ having the β, γ-unsaturated carbon may be represented by the following Chemical Formula 1.

[Formula 1]

In Formula 1, R1 to R4 are each independently selected from the group consisting of hydrogen, C ₁ ~ C ₁₇ alkyl or haloalkyl group, C ₂ ~ C ₁₇ alkenyl group, phenyl (phenyl), and benzyl group will be.

In addition, the sulfonate compound of the present invention may be a linear or cyclic compound, and may be a compound represented by the following Chemical Formulas 2, 3, or 4. Non-limiting examples thereof include bis (allylsulfonyl) methane, bis (allylsulfonyl) ethane, bis (allylsulfonyl) propane , Bis (allylsulfonyl) butane, bis (2-butenylsulfonyl) methane, bis (2-butenylsulfonyl) ethane (bis (2-butenylsulfonyl) butane ) ethane), bis (2-butenylsulfonyl) propane, bis (2-butenylsulfonyl) butane (bis (2-butenylsulfonyl) butane), bis (2,4-hexadiene Bis (2,4-hexadienylsulfonyl) methane, bis (2,4-hexadienylsulfonyl) ethane, bis (2,4-hexadienylsulfonyl) methane Propane (bis (2,4-hexadienylsulfonyl) propane), Bis (2,4-hexadienylsulfonyl) butane (bis (2,4-hexadienylsulfonyl) butane), 1,2,3-tris (allylsulfonyl) Propane (1,2,3-tris (allylsulfonyl) propane), 1,2,3-tris (2-butenylsulfonyl) propane (1,2,3-tris (2-buteny) lsulfonyl) propane), 1,2,3-tris (2,4-hexadienylsulfonyl) propane (1,2,3-tris (2,4-hexadienylsulfonyl) propane), 1,3,5-tris (allyl Sulfonyl) pentane (1,3,5-tris (allylsulfonyl) pentane), 1,3,5-tris (2-butenylsulfonyl) pentane (1,3,5-tris (2-butenylsulfonyl) pentane), 1 , 3,5-tris (2,4-hexadienylsulfonyl) pentane (1,3,5-tris (2,4-hexadienylsulfonyl) pentane), 1,1,1-tris (allylsulfonylmethyl) propane ( 1,1,1-tris (allylsulfonylmethyl) propane), 1,1,1-tris (allylsulfonylethyl) propane (1,1,1-tris (allylsulfonylethyl) propane), 1,1,1-tris (2 -Butenylsulfonylmethyl) propane (1,1,1-tris (2-butenylsulfonylmethyl) propane), 1,1,1-tris (2-butenylsulfonylethyl) propane (1,1,1-tris (2- butenylsulfonylethyl) propane), 1,1,1-tris (2,4-hexadienylsulfonylmethyl) propane (1,1,1-tris (2,4-hexadienylsulfonylmethyl) propane), 1,1,1-tris ( 2,4-hexadienylsulfonylethyl) propane (1,1,1-tris (2,4-hexadienylsulfonylethyl) propane), tetrakis (allylsulfonyl) Tetrakis (allylsulfonyl) neopentane, tetrakis (2-butenylsulfonyl) neopentane, tetrakis (2,4-hexadienylsulfonyl) tepentane (2, 4-hexadienylsulfonyl) neopentane), 1,5-bis (3,3-diallylsulfonyl) allylsulfonylpentane (1,5-bis- (3,3-diallylsulfonyl) allylsulfonylpentane), 1,5-bis , 3-diallylsulfonylmethyl) allylsulfonylpentane (1,5-bis- (3,3-diallylsulfonylmethyl) allylsulfonylpentane), 1,5-bis (3,3-di-2-butenylsulfonyl) -2 -Butenylsulfonylpentane (1,5-bis- (3,3-di-2-butenylsulfonyl) -2-butenylsulfonylpentane), 1,5-bis (3,3-di-2-butenylsulfonylmethyl) -2 -Butenylsulfonylpentane (1,5-bis- (3,3-di-2-butenylsulfonylmethyl) -2-butenylsulfonylpentane), 1,3,5-tris (allylsulfonyl) cyclohexane (1,3,5- tris (allylsulfonyl) cyclohexane, 1,3,5-tris (2-butenylsulfonyl) cyclohexane (1,3,5-tris (2-butenylsulfonyl) cyclohexane), 1,3,5-tris (2,4 Hexadienylsulfonyl) cyclohexane (1,3,5-tris (2,4-hex) adienylsulfonyl) cyclohexane), 1,3,5-tris (allylsulfonyl) benzene (1,3,5-tris (allylsulfonyl) benzene), 1,3,5-tris (2-butenylsulfonyl) benzene (1, 3,5-tris (2-butenylsulfonyl) benzene), 1,3,5-tris (2,4-hexadienylsulfonyl) benzene (1,3,5-tris (2,4-hexadienylsulfonyl) benzene) There is this.

[Formula 2]

In Formula 2, at least one of R ₅ and R ₆ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, the rest is hydrogen, C ₁ ~ C ₆ Alkyl group or haloalkyl group, C ₂ ~ C ₆ alkenyl group, phenyl, (phenyl) group, and a benzyl (benzyl) groups will selected from the group consisting of, n is an integer from 1-6;

(3)

In Formula 3, R ₇ is one of hydrogen, C ₁ ~ alkenyl, phenyl (phenyl) in C ₆ alkyl group or a haloalkyl group, C ₂ ~ C ₆ atoms, or benzyl (benzyl) group, R ₈ ~ R ₁₀ At least one is a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the others are independently the same as defined in R ₇ , n is an integer of 1 to 6, m is an integer of 0 to 6 to be;

[Formula 4]

In Formula 4, at least one of R ₁₁ to R ₁₄ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the rest are each independently hydrogen, C ₁ ~ C ₆ alkyl group or haloalkyl group , C ₂ ~ C ₆ Alkenyl group, phenyl (phenyl), and benzyl (benzyl) group selected from the group consisting of, n is an integer of 1-6, m is an integer of 0-6.

In the electrolyte solution of the present invention, the content of the sulfonate compound may be adjusted according to the goal of improving the performance of the battery, but preferably 0.1 to 20 parts by weight per 100 parts by weight of the electrolyte. If less than 0.1 part by weight, the desired performance improvement effect is insignificant, and if it exceeds 20 parts by weight, the resistance of the battery may increase.

The secondary battery electrolyte of the present invention may include, in addition to the sulfonate-based compound, conventional electrolyte components known in the art, such as electrolyte salts and electrolyte solvents.

The electrolyte salt is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+,, and comprising an alkali metal cation or an ion composed of a combination thereof, such as K ⁺ B ^- is PF ₆ ^-, BF _{^{4 -, Cl -, Br -}} , I -, ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C (CF 2 SO 2) 3 ^- is a salt containing an anion ion or a combination thereof, such as. In particular, lithium salts such as LiClO ₄ , LiCF ₃ SO ₃ , LiPF ₆ , LiBF ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , or Li (CF ₃ SO ₂ ) ₂ are preferred.

In addition, the electrolyte solvent may be used conventional organic solvents known in the art, such as cyclic carbonate and / or linear carbonate. In particular, in order to increase the dissociation and transfer ability of lithium ions of the electrolyte, it is preferable to use a cyclic carbonate having a high polarity, and to mix the cyclic carbonate and linear carbonate in order to prevent a decrease in the lithium ion conductivity due to the viscosity increase of the electrolyte. By doing so, it is more preferable to improve the life characteristics of the battery. Non-limiting examples of the solvent solvent is propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxy Ethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate, ethyl formate Propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate, butyl propionate or halogen derivatives thereof. These electrolyte solvents may be used alone or in combination of two or more thereof. For example, ethylene carbonate and propylene carbonate may be mixed to solve the problem of lowering the low temperature performance of ethylene carbonate.

In addition, the present invention is formed by the electrical reduction of the sulfonate-based compound having two or more sulfonate groups, at least one of the sulfonate groups substituted with a C ₃ ~ C ₂₀ alkenyl group having a β, γ-unsaturated carbon A solid electrolyte interface (SEI) film provides an electrode, preferably a cathode, formed on part or all of the surface. The electrode is assembled by a battery unit using an electrode prepared according to a conventional method known in the art and the electrolyte containing the sulfonate-based compound, and then charged and discharged one or more times to form an SEI film on the surface of the electrode active material Can be prepared. In addition, before assembly of the battery unit, the electrode containing the sulfonate-based compound may be electrically reduced in the state of being impregnated with an electrode prepared according to a conventional method known in the art to prepare an electrode having an SEI film preformed thereon.

The electrode before the SEI film is formed can be prepared according to a conventional method known in the art, for example, a slurry by mixing and stirring a solvent, a binder, a conductive material, a dispersant as necessary in the electrode active material. After the preparation, it may be prepared by coating (coating), compressing and drying the current collector of a metal material.

As the negative electrode active material, a conventional negative electrode active material that can be used for a negative electrode of a conventional secondary battery can be used. Non-limiting examples thereof include lithium adsorbents such as lithium metal or lithium alloy carbon, petroleum coke, activated carbon, graphite, graphite, graphitized carbon or other carbons. It is preferable to use graphitized carbon having a crystal surface distance constant d002 of a carbonaceous material measured by X-ray diffraction method up to 0.338 nm and a specific surface area measured by BET method up to 10 m ² / g. Non-limiting examples of cathode current collectors include foils made of copper, gold, nickel or copper alloys or combinations thereof.

Furthermore, the secondary battery of the present invention has two or more sulfonate groups, and at least one of the sulfonate groups comprises a sulfonate compound substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon. An electrolyte solution and / or a solid electrolyte interface (SEI) film formed by electrical reduction of the sulfonate compound includes an electrode formed on part or all of the surface. Preferably, the present invention provides a separator, an anode, and a cathode in which a solid electrolyte interface (SEI) film formed by electrical reduction of the sulfonate compound is formed on part or all of a surface thereof; And / or provides a secondary battery having an electrolyte solution containing the sulfonate-based compound.

Non-limiting examples of the secondary battery includes a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.

The positive electrode to be applied to the secondary battery of the present invention is not particularly limited, and according to a conventional method known in the art, the positive electrode active material may be prepared in a form bound to the positive electrode current collector. The positive electrode active material may be a conventional positive electrode active material that can be used for the positive electrode of a conventional secondary battery, non-limiting examples of lithium such as LiM _x O _y (M = Co, Ni, Mn, Co _a Ni _b Mn _c ) Transition metal composite oxides (for example, lithium manganese composite oxides such as LiMn ₂ O ₄ , lithium nickel oxides such as LiNiO ₂ , lithium cobalt oxides such as LiCoO ₂ , and some of the manganese, nickel and cobalt oxides of these oxides And the like, or a vanadium oxide containing lithium) or a chalcogen compound (for example, manganese dioxide, titanium disulfide, molybdenum disulfide, and the like). Preferably LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), LiNi _1-Y Co _Y O ₂ , LiCo _1-Y Mn _Y O ₂ , LiNi _1-Y Mn _Y O ₂ (where 0 ≦ Y <1), Li (Ni _a Co _b Mn _c ) O ₄ (0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn _2-z Ni _z O ₄ , LiMn _2-z Co _z O ₄ ( Here, 0 <Z <2), LiCoPO ₄ , LiFePO _4, or a mixture thereof is mentioned. Non-limiting examples of the positive electrode current collector include a foil made of aluminum, nickel, or a combination thereof.

The separator is not particularly limited, but a porous separator may be used, for example, a polypropylene-based, polyethylene-based, or polyolefin-based porous separator.

The secondary battery according to the present invention may be manufactured according to a conventional method known in the art, for example, an electrolyte prepared according to the present invention after assembling a separator between an anode and a cathode. It can be prepared by injecting.

The shape of the secondary battery according to the present invention is not limited, but can be cylindrical, coin-shaped, square or pouch (pouch) of the can.

Furthermore, the present invention provides a compound having a structure of Formula 3 or 4.

(3)

In Formula 3, R ₇ is one of hydrogen, C ₁ ~ alkenyl, phenyl (phenyl) in C ₆ alkyl group or a haloalkyl group, C ₂ ~ C ₆ atoms, or benzyl (benzyl) group, R ₈ ~ R ₁₀ At least one is a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the others are independently the same as defined in R ₇ , n is an integer of 1 to 6, m is an integer of 0 to 6 to be;

[Formula 4]

In Formula 4, at least one of R ₁₁ to R ₁₄ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the rest are each independently hydrogen, C ₁ ~ C ₆ alkyl group or haloalkyl group , C ₂ ~ C ₆ Alkenyl group, phenyl (phenyl), and benzyl (benzyl) group selected from the group consisting of, n is an integer of 1-6, m is an integer of 0-6.

The compound of Formula 3 or 4 may be prepared by reacting a sulfonyl halide compound of Formula 5 with a trivalent or tetravalent alcohol compound.

[Chemical Formula 5]

In Formula 5, R ₁₅ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, X is a halogen element (F, Cl, Br, I).

The electrolytic solution of the present invention can improve the capacity storage characteristics, lifespan performance and the like of the secondary battery by forming a denser and more stable SEI film on the surface of the negative electrode.

Various modifications may be made without departing from the spirit and scope of the invention as set forth in the claims.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples serve to illustrate the present invention, and the scope of the present invention is not limited thereto.

<Production Example of Compound>

Example 1 Preparation of Bis (allylsulfonyl) ethane

150 ml of acetonitrile (CH ₃ CN) was charged with 22.4 g (0.16 mol) of allylsulfonyl chloride and 5 g (0.08 mol) of ethyleneglycol. After the temperature of the reaction vessel was lowered to 0 ^° C., 16.2 g (0.16 mol) of triethylamine was slowly added dropwise, followed by stirring for 2 hours to proceed with the reaction.

After diluting the reaction mixture with 100 mL of water, the organic layer was extracted with ethyl acetate (EtOAc), and sodium sulfate (Na ₂ SO ₄ ) was added thereto to remove excess water. Thereafter, the reaction mixture obtained by concentration using a rotary evaporator was purified by chromatography.

From the above, 17.3 g (80% yield) of bis (allylsulfonyl) ethane (bis (allylsulfonyl) ethane) was obtained and confirmed by NMR and Mass Spectroscopy.

¹ H NMR (400 MHz, CDCl 3): 5.88 (m, 2H), 5.49 (m, 4H), 4.46 (s, 4H), 3.90 (d, J = 6.5 Hz, 4H).

MS (EI): calcd. for C ₈ H ₁₄ O ₆ S ₂ , 270; Found: 270.

Example 2. Preparation of 1,1,1-tris (allylsulfonylmethyl) propane

17.2 g (0.122 mol) of allylsulfonyl chloride and 1,1,1-tris (hydroxymethyl) propane (1,1,1-tris (hydoxymethyl) propane) in 130 mL of acetonitrile (CH ₃ CN) 5 g (0.037 mol) was added while stirring. After the temperature of the reaction vessel was lowered to 0 ^° C., 12.4 g (0.122 mol) of triethylamine was slowly added dropwise and stirred for 5 hours to proceed with the reaction.

After diluting the reaction mixture with 150 mL of water, the organic layer was extracted with ethyl acetate (EtOAc), and sodium sulfate (Na ₂ SO ₄ ) was added thereto to remove excess water. Thereafter, the reaction mixture obtained by concentration using a rotary evaporator was purified by chromatography.

From this, 12.4 g (75% yield) of 1,1,1-tris (allylsulfonylmethyl) propane (1,1,1-tris (allylsulfonylmethyl) propane) was obtained and confirmed by NMR and Mass Spectroscopy.

¹ H NMR (400 MHz, CDCl3): 5.78 (m, 3H), 5.27 (m, 6H), 4.23 (s, 6H), 3.45 (s, 6H), 1.25 (q, J = 7.3 Hz, 2H), 0.96 (t, J = 7.3 Hz, 3H).

MS (EI): calcd. for C ₁₅ H ₂₆ O ₉ S ₃ , 446; Found: 446.

Example 3 Preparation of Tetrakis (allylsulfonyl) neopentane

150 ml of acetonitrile (CH ₃ CN) was charged with 22.4 g (0.16 mol) of allylsulfonyl chloride and 5 g (0.037 mol) of pentaerythritol. After the temperature of the reaction vessel was lowered to 0 ^° C., 16.2 g (0.16 mol) of triethylamine was slowly added dropwise and stirred for 5 hours to proceed with the reaction.

After diluting the reaction mixture with 100 mL of water, the organic layer was extracted with ethyl acetate (EtOAc), and sodium sulfate (Na ₂ SO ₄ ) was added thereto to remove excess water. Thereafter, the reaction mixture obtained by concentration using a rotary evaporator was purified by chromatography.

14.3 g (70% yield) of tetrakis (allylsulfonyl) neopentane was obtained from the above, and confirmed by NMR and Mass Spectroscopy.

¹ H NMR (400 MHz, CDCl 3): 5.76 (m, 4H), 5.25 (m, 8H), 4.25 (s, 8H), 3.41 (s, 8H).

MS (EI): calcd. for C ₁₇ H ₂₈ O ₁₂ S ₄ , 552; Found: 552.

<Production of Electrolyte and Secondary Battery>

Example 4

Example 4-1. Preparation of Electrolyte

2 parts by weight of bis (allylsulfonyl) ethane (bis (allylsulfonyl) ethane) prepared in Example 1 was added to a 1M LiPF ₆ solution of ethylene carbonate, propylene carbonate, and diethyl carbonate in a volume ratio of 1: 1: 2. Prepared.

Example 4-2. Manufacture of batteries

The negative electrode was mixed with 93 parts by weight of graphitized carbon active material and 7 parts by weight of polyvinylidene difluoride (PVDF) as a solvent, N-methyl-2-pyrrolidone, and mixed in a mixer for 2 hours. It was prepared by coating a copper foil current collector and drying at 130 ° C. The positive electrode was coated with an aluminum foil current collector after mixing for 2 hours in a mixer using N-methyl-2-pyrrolidone as a solvent with 91 parts by weight of LiCoO ₂ , 3 parts by weight of PVDF, and 6 parts by weight of conductive carbon, and at 130 ° C. Dried and prepared. The anode was cut in a circular shape, placed in a coin-shaped can, a separator (celgard 2400) was placed, and the cathode cut in a circular shape was placed. This was sufficiently impregnated with the electrolyte prepared in Example 1-1, and then a coin-type cap was prepared by covering and pressing a coin-type cap.

Example 5.

Electrolyte solution in the same manner as in Example 4 except that 0.5 parts by weight of bis (allylsulfonyl) ethane was added instead of 2 parts by weight; And a secondary battery.

Example 6.

Example 4 except that 2 parts by weight of bis (2-butenylsulfonyl) ethane (bis (2-butenylsulfonyl) ethane) was added instead of bis (allylsulfonyl) ethane to prepare an electrolyte solution. Electrolyte solution in the same manner as; And a secondary battery .

Example 7.

2 parts by weight of 1,1,1-tris (allylsulfonylmethyl) propane (1,1,1-allylsulfonylmethyl) propane prepared in Example 2, instead of bis (allylsulfonyl) ethane Electrolyte solution in the same manner as in Example 4, except that the electrolyte solution was prepared by addition; And a secondary battery.

Example 8.

Except for preparing an electrolyte solution by adding 2 parts by weight of tetrakis (allylsulfonyl) neopentane prepared in Example 3 instead of bis (allylsulfonyl) ethane. , Electrolyte solution in the same manner as in Example 4; And a secondary battery.

Comparative Example 1.

Electrolyte solution in the same manner as in Example 4 except that no compound was added to the LiPF ₆ solution; And a secondary battery.

Comparative Example 2

The same method as in Example 4, except that 2 parts by weight of bis (methylsulfonyl) ethane was added instead of bis (allylsulfonyl) ethane to prepare an electrolyte solution. Electrolytic solution; And a secondary battery.

Experimental Example 1. Performance Evaluation of Lithium Secondary Batteries

The secondary batteries prepared in Examples 4 to 8 and Comparative Examples 1 to 2 were charged at a rate of 0.5 C to 25 V at 4.2 ° C., and charged at 4.2 V until the current became 0.05 mA or less, and 0.5 C to 3 V. Charge and discharge experiments were performed by discharging at a rate of. The discharge capacity retention rate (%) was expressed as a percentage of the ratio of the discharge capacity to the initial discharge capacity after 50 cycles. The results are shown in Table 1.

compound Addition amount (part by weight) Discharge Capacity Retention Rate (%) Example 4 Bis (allylsulfonyl) ethane 2.0 90.7 Example 5 Bis (allylsulfonyl) ethane 0.5 86.2 Example 6 Bis (2-butenylsulfonyl) ethane 2.0 89.3 Example 7 1,1,1-tris (allylsulfonylmethyl) propane 2.0 88.6 Example 8 Tetrakis (allylsulfonyl) neopentane 2.0 91.1 Comparative Example 1 - - 71.8 Comparative Example 2 Bis (methylsulfonyl) ethane 2.0 81.9

As a result, the batteries of Examples 4 to 8 using the sulfonate-based compound of the present invention as constituents of the electrolyte solution showed much higher discharge capacity retention rates than the batteries of Comparative Example 1 using the electrolyte solution without any compound added thereto. In particular, the battery of Examples 4 to 8 of the present invention is about twice as large as the increase in discharge capacity retention rate than the battery of Comparative Example 2 using a sulfonate-based compound which is not substituted with an allyl group as a sulfonate group as an electrolyte solution component. Showed.

From this, a sulfonate-based compound having two or more sulfonate groups, and at least one of the sulfonate groups substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon is used as one of the electrolyte solution. When used as a component, it was confirmed that the capacity storage characteristics and the life performance of the battery can be improved.

Experimental Example 2. Experiment for Confirming Formation of Cathode Surface SEI Film

In order to confirm the formation of the SEI film on the surface of the negative electrode by the sulfonate compound of the present invention, the following experiment was performed.

Each battery prepared in Example 4, Comparative Example 1, and Comparative Example 2 was charged and discharged three times at 0.2 ^° C. at 25 ^° C., and then, the battery was disassembled in a discharged state to collect a negative electrode. Then, the collected negative electrode was subjected to differential scanning calorimetry (DSC) analysis, and the results are shown in FIG. 1. At this time, the exothermic peak of FIG. 1 is assumed to be due to thermal collapse of the SEI film formed on the surface of the cathode.

As a result, the exothermic reaction patterns of the negative electrodes collected from the batteries prepared in Example 4, Comparative Example 1 and Comparative Example 2 were different from each other. That is, the exothermic reaction patterns were different depending on the presence or absence of the electrolyte solution and the electrolyte solution used. From this, it was found that the unsaturated sulfonate compound of the present invention is involved in SEI film formation on the surface of the negative electrode.

In the case of the negative electrode of the battery prepared by Example 4 using the electrolyte solution containing the sulfonate compound of the present invention, the negative electrode and sulfonate group of the battery prepared by Comparative Example 1 using the electrolyte solution without any compound added The exothermic peak was higher than that of the negative electrode of the battery prepared by Comparative Example 2, in which the compound having no group was substituted as the electrolyte solution additive. In general, the higher the exothermic peak temperature in the DSC analysis, the better the thermal stability of the SEI film formed on the surface of the cathode. Therefore, from the above results, it can be seen that when the electrolyte solution containing the sulfonate compound of the present invention is used, a more stable SEI film is formed on the surface of the cathode.

1 is a graph showing the results of performing differential scanning calorimetry (DSC) on a negative electrode collected from each of the batteries prepared in Example 4, Comparative Example 1, and Comparative Example 2. FIG.

Claims (10)

Electrolyte salts; Electrolyte solvents; And an electrolyte containing a sulfonate compound, The sulfonate-based compound has two or more sulfonate groups, and at least one of the sulfonate groups is substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon. The electrolyte according to claim 1, wherein the C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon has a conjugation structure. The electrolyte according to claim 1, wherein the C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon is represented by the following Chemical Formula 1. [Formula 1]

In Chemical Formula 1, R ₁ to R ₄ are each independently hydrogen, a C ₁ to C ₁₇ alkyl group or haloalkyl group, C ₂ to C ₁₇ alkenyl group, a phenyl group, and a benzyl group. Is selected from. The electrolyte solution according to claim 1, wherein the sulfonate-based compound is a compound represented by any one of the following Chemical Formulas 2-4. [Formula 2]

In Formula 2, at least one of R ₅ and R ₆ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, the rest is hydrogen, C ₁ ~ C ₆ Alkyl group or haloalkyl group, C ₂ ~ C ₆ alkenyl group, phenyl, (phenyl) group, and a benzyl (benzyl) groups will selected from the group consisting of, n is an integer from 1-6; (3)

In Chemical Formula 3, R ₇ is hydrogen, an alkyl group or haloalkyl group of C ₁ to C _6, an alkenyl group of C ₂ to C ₆ , a phenyl group, or a benzyl group, and R ₈ to R _10. At least one is an alkenyl group of C ₃ ~ C ₂₀ having β, γ-unsaturated carbon, and the rest are each independently the same as defined in R ₇ , n is an integer of 1-6, m is 0-6 Is an integer; [Formula 4]

In Formula 4, at least one of R ₁₁ to R ₁₄ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the rest are each independently hydrogen, C ₁ ~ C ₆ alkyl group or haloalkyl group , C ₂ ~ C ₆ Alkenyl group, phenyl (phenyl), and benzyl (benzyl) group selected from the group consisting of, n is an integer of 1-6, m is an integer of 0-6. The method of claim 1, wherein the sulfonate compound is bis (allylsulfonyl) methane, bis (allylsulfonyl) ethane, bis (allylsulfonyl) propane (bis (allylsulfonyl) propane), bis (allylsulfonyl) butane, bis (2-butenylsulfonyl) methane, bis (2-butenylsulfonyl) Ethane (bis (2-butenylsulfonyl) ethane), bis (2-butenylsulfonyl) propane, bis (2-butenylsulfonyl) butane (bis (2-butenylsulfonyl) butane) (2,4-hexadienylsulfonyl) methane (bis (2,4-hexadienylsulfonyl) methane), bis (2,4-hexadienylsulfonyl) ethane (bis (2,4-hexadienylsulfonyl) ethane), bis (2 , 4-hexadienylsulfonyl) propane (bis (2,4-hexadienylsulfonyl) propane), bis (2,4-hexadienylsulfonyl) butane (bis (2,4-hexadienylsulfonyl) butane) 1,2,3 -Tris (allylsulfonyl) propane (1,2,3-tris (allylsulfonyl) propane), 1,2,3-tris (2-butenylsulfonyl) Ropan (1,2,3-tris (2-butenylsulfonyl) propane), 1,2,3-tris (2,4-hexadienylsulfonyl) propane (1,2,3-tris (2,4-hexadienylsulfonyl) propane), 1,3,5-tris (allylsulfonyl) pentane (1,3,5-tris (allylsulfonyl) pentane), 1,3,5-tris (2-butenylsulfonyl) pentane (1,3, 5-tris (2-butenylsulfonyl) pentane), 1,3,5-tris (2,4-hexadienylsulfonyl) pentane (1,3,5-tris (2,4-hexadienylsulfonyl) pentane), 1,1 , 1-tris (allylsulfonylmethyl) propane (1,1,1-tris (allylsulfonylmethyl) propane), 1,1,1-tris (allylsulfonylethyl) propane (1,1,1-tris (allylsulfonylethyl) propane), 1,1,1-tris (2-butenylsulfonylmethyl) propane (1,1,1-tris (2-butenylsulfonylmethyl) propane), 1,1,1-tris (2-butenylsulfonyl ethyl) Propane (1,1,1-tris (2-butenylsulfonylethyl) propane), 1,1,1-tris (2,4-hexadienylsulfonylmethyl) propane (1,1,1-tris (2,4-hexadienylsulfonylmethyl propane), 1,1,1-tris (2,4-hexadienylsulfonylethyl) propane (1,1,1-tris (2,4-hexadienylsulfonylethyl) propane), tet Tetrakis (allylsulfonyl) neopentane, tetrakis (2-butenylsulfonyl) neopentane, tetrakis (2,4-hexadienylsulfonyl) neo Pentane (tetrakis (2,4-hexadienylsulfonyl) neopentane), 1,5-bis (3,3-diallylsulfonyl) allylsulfonylpentane (1,5-bis- (3,3-diallylsulfonyl) allylsulfonylpentane), 1 , 5-bis (3,3-diallylsulfonylmethyl) allylsulfonylpentane (1,5-bis- (3,3-diallylsulfonylmethyl) allylsulfonylpentane), 1,5-bis (3,3-di-2- Butenylsulfonyl) -2-butenylsulfonylpentane (1,5-bis- (3,3-di-2-butenylsulfonyl) -2-butenylsulfonylpentane), 1,5-bis (3,3-di-2-butene Nylsulfonylmethyl) -2-butenylsulfonylpentane (1,5-bis- (3,3-di-2-butenylsulfonylmethyl) -2-butenylsulfonylpentane), 1,3,5-tris (allylsulfonyl) cyclohexane ( 1,3,5-tris (allylsulfonyl) cyclohexane, 1,3,5-tris (2-butenylsulfonyl) cyclohexane (1,3,5-tris (2-butenylsulfonyl) cyclohexane), 1,3,5 -Tris (2,4-hexadienylsulfonyl) cycle Rohexane (1,3,5-tris (2,4-hexadienylsulfonyl) cyclohexane), 1,3,5-tris (allylsulfonyl) benzene (1,3,5-tris (allylsulfonyl) benzene), 1,3 , 5-tris (2-butenylsulfonyl) benzene (1,3,5-tris (2-butenylsulfonyl) benzene), and 1,3,5-tris (2,4-hexadienylsulfonyl) benzene (1, An electrolyte solution characterized by being selected from the group consisting of 3,5-tris (2,4-hexadienylsulfonyl) benzene). The electrolyte of claim 1, wherein the sulfonate-based compound is present in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the electrolyte. A solid electrolyte interface formed by electrical reduction of a sulfonate-based compound having two or more sulfonate groups and at least one of the sulfonate groups substituted with a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon (SEI Electrode with a film formed on part or all of the surface. The electrode according to claim 7, wherein the sulfonate compound is a compound represented by any one of the following Chemical Formulas 2-4. [Formula 2]

In Formula 2, at least one of R ₅ and R ₆ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, the rest is hydrogen, C ₁ ~ C ₆ Alkyl group or haloalkyl group, C ₂ ~ C ₆ alkenyl group, phenyl, (phenyl) group, and a benzyl (benzyl) groups will selected from the group consisting of, n is an integer from 1-6; (3)

In Formula 3, R ₇ is one of hydrogen, C ₁ ~ alkenyl, phenyl (phenyl) in C ₆ alkyl group or a haloalkyl group, C ₂ ~ C ₆ atoms, or benzyl (benzyl) group, R ₈ ~ R ₁₀ At least one is a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the others are independently the same as defined in R ₇ , n is an integer of 1 to 6, m is an integer of 0 to 6 to be; [Formula 4]

In Formula 4, at least one of R ₁₁ to R ₁₄ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the rest are each independently hydrogen, C ₁ ~ C ₆ alkyl group or haloalkyl group , C ₂ ~ C ₆ Alkenyl group, phenyl (phenyl), and benzyl (benzyl) group selected from the group consisting of, n is an integer of 1-6, m is an integer of 0-6. In a secondary battery comprising a positive electrode, a negative electrode and an electrolyte, the secondary battery The electrolyte is a secondary battery electrolyte according to any one of claims 1 to 6; The positive electrode or the negative electrode is an electrode according to any one of claims 7 to 8; or A secondary battery comprising both the electrolyte and the electrode. Compounds having the structure of Formula 3 or 4 (3)

In Formula 3, R ₇ is one of hydrogen, C ₁ ~ alkenyl, phenyl (phenyl) in C ₆ alkyl group or a haloalkyl group, C ₂ ~ C ₆ atoms, or benzyl (benzyl) group, R ₈ ~ R ₁₀ At least one is a C ₃ to C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the others are independently the same as defined in R ₇ , n is an integer of 1 to 6, m is an integer of 0 to 6 to be; [Formula 4]

In Formula 4, at least one of R ₁₁ to R ₁₄ is a C ₃ ~ C ₂₀ alkenyl group having β, γ-unsaturated carbon, and the rest are each independently hydrogen, C ₁ ~ C ₆ alkyl group or haloalkyl group , C ₂ ~ C ₆ Alkenyl group, phenyl (phenyl), and benzyl (benzyl) group selected from the group consisting of, n is an integer of 1-6, m is an integer of 0-6.

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