KR101094580B1 - Allylsulfonate derivative and secondary battery using the same - Google Patents

Abstract

The present invention provides a novel allylsulfonate derivative, a nonaqueous electrolyte containing an allylsulfonate derivative, an electrode on which a solid electrolyte interface (SEI) film is formed on the surface, and the nonaqueous electrolyte and / or an electrode to preserve the capacity of a battery. The present invention relates to a secondary battery having improved characteristics and lifetime characteristics. Specifically, the allylsulfonate derivative of the present invention is represented by the formula CH ₂ = CH-CH ₂ -SO ₂ -OR, R is an alkyl group having 1 to 20 carbon atoms containing at least one halogen atom, at least one halogen atom Is selected from the group consisting of a cycloalkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms including one or more halogen atoms, and a benzyl group containing one or more halogen atoms, wherein the halogen atoms are F, Cl , Br and I.

Description

Allylsulfonate derivative and secondary battery using same {ALLYLSULFONATE DERIVATIVE AND SECONDARY BATTERY USING THE SAME}

The present invention provides a novel allylsulfonate derivative, a nonaqueous electrolyte containing an allylsulfonate derivative, an electrode on which a solid electrolyte interface (SEI) film is formed on the surface, and the nonaqueous electrolyte and / or an electrode to preserve the capacity of a battery. The present invention relates to a secondary battery having improved characteristics and lifetime characteristics.

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.

Secondary batteries generally have a positive electrode using a lithium metal oxide such as LiCoO ₂ as a positive electrode active material, a negative electrode using a carbonaceous material as a negative electrode active material, and a porous separator of a polymer material between the positive electrode and the negative electrode such as LiPF ₆ and LiBF _4. It can be prepared using a non-aqueous electrolyte solution in which lithium salt is dissolved as a transfer medium for lithium ions.

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. .

However, conventional electrolyte solvents, such as carbonate-based organic solvents, may decompose on the electrode surface during charge and discharge, causing side reactions in the battery. In particular, propylene carbonate (PC) solvent is co-intercalated between the graphite layers at the carbon-based negative electrode, The structure of the cathode may be disrupted.

On the other hand, the problem can be solved by a solid electrolyte interface (SEI) film formed on the surface of the negative electrode by the electrical reduction of the carbonate-based organic solvent during the initial charging of the battery. However, since lithium ions in the electrolyte are irreversibly involved in forming the SEI film, there is a problem that the initial capacity of the battery is essentially reduced, which is particularly problematic in a carbon material negative electrode having a small theoretical capacity.

In addition, the SEI film formed above is generally not electrochemically stable and easily collapses. Therefore, side reactions such as decomposition of the electrolyte may occur on the surface of the negative electrode during charging and discharging of the battery, and thus battery capacity may be continuously reduced. In addition, a phenomenon in which the battery swells or the internal pressure increases may occur due to the gas generated by the side reaction.

In order to solve the above problems, a method of adding 1,3-propanesultone (Japanese Patent Application No. 1999-339850) to the electrolyte has been proposed. However, the above method shows an effect of reducing battery capacity at the beginning of charge / discharge, but shows a result of gradually decreasing capacity as the cycle continues, and there are still problems as described above.

Generally it is known that a stable solid electrolyte interface (SEI) membrane is formed when a cyclic sulfonate compound (typically 1,3-propane sultone) is used as an electrolyte additive in a secondary battery, whereas in the case of a linear sulfonate compound It is known that the effect is small compared with a sulfonate compound.

However, the inventors of the present invention can improve the capacity retention characteristics of a battery by forming a stable solid electrolyte interfacial film on a negative electrode of a secondary battery when an allyl sulfonate derivative including a halogen atom is used as an electrolyte additive in a linear sulfonate compound. It turns out that it is.

Accordingly, an object of the present invention is to provide a novel allylsulfonate derivative, and a nonaqueous electrolyte and an electrode using the same. In addition, an object of the present invention is to provide a secondary battery comprising the nonaqueous electrolyte and / or the electrode.

The present invention provides an allylsulfonate derivative represented by the following formula (1).

[Formula 1]

In Formula 1, R is an alkyl group having 1 to 20 carbon atoms including one or more halogen atoms, a cycloalkyl group having 3 to 8 carbon atoms including one or more halogen atoms, and an aryl having 6 to 12 carbon atoms including one or more halogen atoms ) And a benzyl group containing one or more halogen atoms; The halogen atom is selected from the group consisting of F, Cl, Br and I.

In addition, the present invention is an allyl sulfonate derivative represented by Formula 1; Electrolyte solvents; And it provides a nonaqueous electrolyte containing an electrolyte salt.

The present invention also provides an electrode in which a solid electrolyte interface (SEI) film including a reduced substance of the allylsulfonate derivative represented by Chemical Formula 1 is formed on part or all of the surface thereof.

In addition, the present invention provides a secondary battery including the nonaqueous electrolyte and / or the electrode.

According to the present invention, by using the allylsulfonate derivative represented by Chemical Formula 1 as an electrolyte additive, a more stable solid electrolyte interface (SEI) film can be formed on the negative electrode surface of the secondary battery, and further, the capacity storage characteristics and the life characteristics of the battery. Can improve.

In the present invention, the allylsulfonate derivative represented by Formula 1 is a linear sulfonate-based compound, and may be used as a nonaqueous electrolyte additive as a novel compound including one or more halogen atoms.

The halogen atom may be selected from F, Cl, Br and I, with F (fluorine) being preferred.

Examples of the allylsulfonate derivative represented by Formula 1 in the present invention, fluoromethyl allylsulfonate, difluoromethyl allylsulfonate, trifluoromethyl allylsulfonate, trifluoromethyl allyllsulfonate ), 2-fluoroethyl allylsulfonate, 2,2-difluoroethyl allylsulfonate, 2,2,2-trifluoroethyl allylsulfonate (2,2,2-trifluoroethyl allylsulfonate), pentafluoroethyl allylsulfonate, 3-fluoropropyl allylsulfonate, 3,3-difluoropropyl allylsulfonate ( 3,3-difluoropropyl allylsulfonate), 3,3,3-trifluoropropyl allylsulfonate (3,3,3-trifluoropropyl allylsulfonate), 2,2,3,3,3-pentafluoropropyl allylsulfonate ( 2,2,3,3,3-pentafluoropro pyl allylsulfonate, hexafluoroisopropyl allylsulfonate, 1H, 1H, 3H-hexafluorobutyl allylsulfonate (1H, 1H, 3H-hexafluorobutyl allylsulfonate), 2- (perfluorobutyl) ethyl 2- (perfluorobutyl) ethyl allylsulfonate, 3- (perfluorobutyl) propyl allylsulfonate, 2- (perfluorohexyl) ethyl allylsulfonate (2- (perfluorohexyl) ethyl allylsulfonate, 3- (perfluorohexyl) propyl allylsulfonate, 2- (perfluorooctyl) ethyl allylsulfonate (2- (perfluorooctyl) ethyl allylsulfonate) 3- (perfluorooctyl) propyl allylsulfonate, 2- (perfluorodecyl) ethyl allylsulfonate, 3- (perfluorooctyl) propyl allylsulfonate Rodecyl) propyl allylsulfonate (3- (perfluorodecyl) propyl allylsulfonate), 4-pleat 4-fluorophenyl allylsulfonate, 3-fluorophenyl allylsulfonate, 2,4-difluorophenyl allylsulfonate, pentafluoro Pentafluorophenyl allylsulfonate, 4-fluorobenzyl allylsulfonate, 3-fluorobenzyl allylsulfonate, 2,4-difluorobenzyl allylsulfonate (2,4-difluorobenzyl allylsulfonate), pentafluorobenzyl allylsulfonate, and the like, but are not limited thereto.

The allylsulfonate derivative represented by Formula 1 according to the present invention may be prepared by reacting an allylsulfonyl halide compound and an alcohol compound including a halogen atom according to Scheme 1 below.

Scheme 1

In Scheme 1, R is the same as defined in Formula 1; X is selected from the group consisting of F, Cl, Br, and I.

The present invention provides a sulfonate-based solid electrolyte interface (SEI) membrane containing a halogen atom, preferably a fluorine atom, on a negative electrode surface by using an allylsulfonate derivative represented by Formula 1 as one component of a nonaqueous electrolyte. It is characterized by improving the charge and discharge capacity storage characteristics of the battery.

In general, the SEI membrane formed by the carbonate-based organic solvent is weak, porous and not dense, and is easily collapsed by increased electrochemical energy and thermal energy as charging and discharging proceeds. In addition, this may result in a sustained side reaction between the exposed negative electrode surface and the surrounding electrolyte solution, thereby continually consuming lithium ions in the battery, and in addition, lowering the capacity and life characteristics of the battery.

Thus, in the present invention, by using the allylsulfonate derivative represented by Chemical Formula 1 as an electrolyte additive, it is possible not only to form an SEI film at an early stage but also to form a more stable SEI film, thereby improving capacity storage characteristics of the battery. The overall performance improvement of the battery can be estimated as follows, but is not limited thereto.

Specifically, the allylsulfonate derivative represented by Formula 1 used as one component of the electrolyte in the present invention may form an SEI film on the surface of the cathode during initial charging, wherein the resulting SEI film is a halogen atom, preferably fluorine Sulfonate radicals containing the lean component (ROSO ₂ ⁻ ) and allyl radicals introduced into the sulfonate groups of the derivatives can be formed. The sulfonate radicals containing the halogen atom, preferably the fluorine component, are combined with lithium ions in the electrolyte (ROSO ₂ ^- Li ⁺ ), which are polymerizable functional groups, and together with other electrolyte components, undergo various types of polymerization reactions. Can be done. As a result, in the present invention, a more stable SEI film can be formed compared to the SEI film formed by the conventional carbonate organic solvent.

That is, the allylsulfonate derivative represented by Chemical Formula 1 of the present invention will form an allyl radical and a sulfonate radical while the sulfur-carbon bond is broken as shown in Chemical Formula 2 below, wherein the allyl radical has a resonance structure. It is an energy stable intermediate because it has Thus, the formation of allyl radicals and sulfonate radicals in reductive degradation is advantageously kinetic, which means that the halogen-containing sulfonate radicals (ROSO ₂ ⁻ ), for example fluoroalkyl sulfonate radicals, When performing various types of polymerization reactions with other electrolyte components, it may also be advantageously kinetic.

[Formula 2]

In formula (2), R is the same as defined in formula (1).

In addition, since the SEI film produced at this time contains not only sulfonate but also halogen atoms, preferably fluorine, not only thermal stability of the SEI film but also an effect of reducing interfacial resistance and improving lithium ion conductivity.

In the non-aqueous electrolyte of the present invention, the content of the allylsulfonate derivative represented by Chemical Formula 1 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. When the content of the allylsulfonate derivative represented by Formula 1 is less than 0.1 part by weight, the desired cycle preservation effect is insignificant, and when the content of the allylsulfonate derivative is greater than 20 parts by weight, the resistance of the battery may increase.

The nonaqueous electrolyte solution of the present invention includes conventional electrolyte solution components known in the art, for example, an electrolyte salt and an electrolyte solvent, in addition to the allylsulfonate derivative represented by Chemical Formula 1.

The electrolyte solvent is not particularly limited as long as it is usually used as an organic solvent for nonaqueous electrolyte, and cyclic carbonate, linear carbonate, lactone, ether, ester, acetonitrile, lactam, ketone and / or halogen derivatives thereof may be used.

Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), and the like. Examples of the linear carbonate include diethyl carbonate (DEC) and dimethyl carbonate. (DMC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methyl propyl carbonate (MPC), and the like. Examples of the lactone include gamma butyrolactone (GBL), and examples of the ether include dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane and the like. Examples of such esters include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl pivalate and the like. In addition, the lactam includes N-methyl-2-pyrrolidone (NMP) and the like, and the ketone includes polymethylvinyl ketone. In addition, these organic solvents can be used individually or in mixture of 2 or more types.

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. Moreover, in order to prevent the fall of lithium ion conductivity by the viscosity increase of electrolyte solution, it is more preferable to mix cyclic carbonate and linear carbonate. As a non-limiting example, ethylene carbonate and propylene carbonate may be mixed to solve the problem of low temperature performance of ethylene carbonate.

The electrolyte salt which can be used for the electrolyte solution of the present invention is not particularly limited as long as it is usually used as an electrolyte salt for nonaqueous electrolyte solution. The electrolytic salt, non-limiting example, A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, K ^+, and contains such an alkali metal cation or a cation made of a combination of 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 And an anion consisting of anions such as SO ₂ ) ₃ ⁻ or a combination thereof, and a salt consisting of a combination of the cation and an anion. In particular, lithium salts are preferred. These electrolyte salts can be used individually or in mixture of 2 or more types.

The electrode according to the present invention is an electrode having a solid electrolyte interface (SEI) film formed on part or all of its surface, and the SEI film is characterized in that it comprises a reducing agent of the allylsulfonate derivative represented by Chemical Formula 1.

The reducing agent of the allylsulfonate derivative represented by Chemical Formula 1 is produced by reduction decomposition of the allylsulfonate derivative represented by Chemical Formula 1 as described above, and includes an allyl radical and a sulfonate radical containing a halogen atom (ROSO _2). ^- ) And may further include the result of the chemical reaction between the radicals and the non-aqueous electrolyte component. In addition, the SEI film may be formed during initial charging or subsequent charge / discharge of the secondary battery.

The electrode according to the present invention can be prepared by reducing the electrode prepared according to a conventional method known in the art one or more times in a non-aqueous electrolyte containing an allylsulfonate derivative represented by the formula (1). In addition, the electrode according to the present invention is a porous separator between the positive electrode and the negative electrode prepared by a conventional method known in the art, and a non-aqueous electrolyte containing an allylsulfonate derivative represented by the formula (1) After that, it can be prepared by charging one or more times.

A secondary battery according to the present invention is a secondary battery comprising a positive electrode, a negative electrode and a nonaqueous electrolyte, (i) the nonaqueous electrolyte is a nonaqueous electrolyte according to the present invention; Or (ii) at least one of the positive electrode and the negative electrode comprises: an electrode in which a solid electrolyte interface (SEI) film is formed on part or all of the surface according to the present invention; Or (iii) both (i) and (ii).

The secondary battery according to the present invention is preferably a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.

The secondary battery of the present invention can be prepared according to conventional methods known in the art. For example, the non-aqueous electrolyte according to the present invention may be prepared by placing a porous separator between the positive electrode and the negative electrode.

In the secondary battery of the present invention, the electrodes (anode and / or negative electrode) may be conventional electrodes in which no SEI film is formed, and / or electrodes in which a solid electrolyte interface (SEI) film is formed on part or all of the surface according to the present invention. .

In this case, the conventional electrode in which the SEI film is not formed may be manufactured by a conventional method known in the art. For example, a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant in an electrode active material, and then applying (coating) to a current collector of a metal material, compressing, and drying the electrode to prepare an electrode. have.

The electrode active material may be a positive electrode active material or a negative electrode active material.

As the cathode active material, a conventional cathode active material that can be used for the cathode of a conventional secondary battery may be used, and a non-limiting example thereof is 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.

The negative electrode active material may be a conventional negative electrode active material that can be used for the negative electrode of the conventional electrochemical device, non-limiting examples thereof lithium metal, lithium alloy, carbon, petroleum coke that can occlude and release lithium ions ), Activated carbon, graphite (graphite), carbon fiber (carbon fiber), graphitized carbon, or other lithium adsorbents such as carbons. In addition, metal oxides such as TiO ₂ , SnO _2, and the like, which can occlude and release lithium, and have a potential with respect to lithium of less than 2V, can be used. In particular, carbon materials, such as graphite, carbon fiber, activated carbon, and graphitized carbon, are preferable.

The current collector of the metal material is a metal having high conductivity, and any metal can be used as long as the slurry of the electrode active material can be easily adhered and is not reactive in the voltage range of the battery. Non-limiting examples of the positive electrode current collector is a foil produced by aluminum, nickel or a combination thereof, and non-limiting examples of the negative electrode current collector is produced by copper, gold, nickel or copper alloy or a combination thereof Foil and the like.

Non-limiting examples of binders that can be used include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and the like.

The conductive material is not particularly limited as long as it is an electronic conductive material that does not cause chemical change in the electrochemical device. In general, carbon black, graphite, carbon fiber, carbon nanotubes, metal powder, conductive metal oxide, organic conductive materials, and the like can be used, and currently commercially available products as acetylene black series (Chevron Chemical) Chevron Chemical Company or Gulf Oil Company, etc., Ketjen Black EC series (Armak Company), Vulcan XC-72 (Cabot Company) (Cabot Company)) and Super P (MMM), but are not limited thereto.

Non-limiting examples of the solvent include an organic solvent such as NMP (N-methyl pyrrolidone), DMF (dimethyl formamide), acetone, dimethyl acetamide or water, and these solvents alone or in combination of two or more thereof. Can be used. The amount of the solvent is sufficient to dissolve and disperse the electrode active material, the binder, and the conductive material in consideration of the coating thickness of the slurry and the production yield.

The separator is not particularly limited, but it is preferable to use a porous separator, and non-limiting examples include a polypropylene-based, polyethylene-based, or polyolefin-based porous separator.

The appearance 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.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are merely to illustrate the invention and the present invention is not limited by the following examples.

Synthesis Example 1 Synthesis of 2,2,2-trifluoroethyl allylsulfonate

14 g (0.14 mol) of 2,2,2-trifluoroethanol and 20 g (allylsulfonyl chloride) in 20 mL (0.14 mol) of acetonitrile (CH ₃ CN) Was added while stirring. After the temperature of the reaction vessel was lowered to 0 ° C., 14.5 g (0.14 mol) of triethylamine was slowly added dropwise, followed by stirring for 2 hours to proceed with the reaction (see Scheme 2 below).

Scheme 2

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 distillation (50 ° C, 1 mmHg).

25 g (86% yield) of 2,2,2-trifluoroethyl allylsulfonate (2,2,2-trifluoroethyl allylsulfonate) was obtained from the above, and confirmed by NMR and Mass Spectroscopy.

¹ H NMR (400 MHz, CDCl 3): δ 5.88 (m, 1H), 5.53 (m, 2H), 4.50 (q, J = 1.5 Hz, 2H), 3.94 (d, J = 6.5 Hz, 2H).

MS (EI): calcd for C ₅ H ₇ F ₃ O ₈ S, 204; Found: 204.

Synthesis Example 2 Synthesis of 4-fluorophenyl allylsulfonate

To 100 mL of acetonitrile (CH ₃ CN), 10 g (0.089 mol) of 4-fluorophenol and 12.5 g (0.089 mol) of allylsulfonyl chloride were added with stirring. After the temperature of the reaction vessel was lowered to 0 ° C., 9.0 g (0.089 mol) of triethylamine was slowly added dropwise, followed by stirring for 2 hours to proceed with the reaction (see Scheme 3 below).

Scheme 3

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. Then, the reaction mixture obtained by concentration using a rotary evaporator was purified by silica gel chromatography. 16.3 g (85% yield) of 4-fluorophenyl allylsulfonate was obtained from the above, and confirmed by NMR and Mass Spectroscopy.

¹ H NMR (400 MHz, CDCl 3): δ 7.26 (m, 2H), 7.09 (t, J = 5.0 Hz, 2H), 5.97 (m, 1H), 5.55 (m, 2H), 3.97 (d, J = 8.0 Hz, 2H).

MS (EI): calcd for C ₉ H ₉ FO ₃ S, 216; Found: 216.

Example 1 Manufacture of Non-aqueous Electrolyte and Secondary Battery

Manufacture of nonaqueous electrolyte

2,2,2-trifluoroethyl allylsulfonate (2,2,2) prepared in Synthesis Example 1 in a 1M LiPF ₆ solution of ethylene carbonate: propylene carbonate: diethyl carbonate = 1: 1: 2 (volume ratio) -trifluoroethyl allylsulfonate) was added 2.0 parts by weight to prepare an electrolyte.

Manufacture of Secondary Battery

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. After coating on a copper foil current collector and dried at 130 ℃.

The positive electrode was coated with an aluminum foil current collector after mixing for 2 hours in a mixer using 91 parts by weight of LiCoO ₂ , 3 parts by weight of PVDF and 6 parts by weight of conductive carbon and a solvent, N-methyl-2-pyrrolidone, at 130 ° C. Dried and prepared.

The anode was cut in a circular shape, placed in a coin-shaped can, and a separator (celgard 2400) was placed, and the cathode cut in a circular shape was placed. This was sufficiently impregnated with the prepared electrolyte, and then covered with a coin-type cap and pressed to produce a coin-type battery.

Example 2 Fabrication of Nonaqueous Electrolyte and Secondary Battery

A nonaqueous electrolyte and a secondary battery were manufactured in the same manner as in Example 1, except that 2,2,2-trifluoroethyl allylsulfonate was added in an amount of 0.5 parts by weight instead of 2.0 parts by weight.

Example 3 Fabrication of Non-Aqueous Electrolyte and Secondary Battery

A nonaqueous electrolyte and a secondary battery were manufactured in the same manner as in Example 1, except that 6.0 parts by weight of 2,2,2-trifluoroethyl allylsulfonate was added instead of 2.0 parts by weight.

Example 4 Fabrication of Nonaqueous Electrolyte and Secondary Battery

A nonaqueous electrolyte and a secondary battery were manufactured in the same manner as in Example 1, except that 10.0 parts by weight of 2,2,2-trifluoroethyl allylsulfonate was added instead of 2.0 parts by weight.

Example 5 Fabrication of Nonaqueous Electrolyte and Secondary Battery

Except for adding 2.0 parts by weight of 4-fluorophenyl allylsulfonate prepared in Synthesis Example 2 instead of 2,2,2-trifluoroethyl allylsulfonate in preparing the nonaqueous electrolyte solution, A nonaqueous electrolyte solution and a secondary battery were manufactured in the same manner as in Example 1.

Comparative Example 1 Manufacture of Non-Aqueous Electrolyte and Secondary Battery

A nonaqueous electrolyte solution and a secondary battery were prepared in the same manner as in Example 1, except that 2,2,2-trifluoroethyl allylsulfonate was not added during the preparation of the nonaqueous electrolyte solution.

Comparative Example 2 Fabrication of Non-Aqueous Electrolyte and Secondary Battery

A nonaqueous electrolyte and a secondary battery were prepared in the same manner as in Example 1, except that 2.0 parts by weight of ethyl allylsulfonate was added instead of 2,2,2-trifluoroethyl allylsulfonate in the preparation of the nonaqueous electrolyte. .

Experimental Example 1 Performance Evaluation of Lithium Secondary Battery

The secondary batteries prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were charged at 25 ° C. to 4.2 V at a rate of 0.5 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 50-cycle discharge capacity retention rate (%) is expressed as a percentage of the ratio of the discharge capacity and the initial discharge capacity after 50 cycles. The results are shown in Table 1 below.

compound Addition wt% Electrolyte composition
(Volume ratio) 50 cycles discharge capacity
Retention rate (%) Example 1 2,2,2-trifluoroethyl allylsulfonate 2.0 1M LiPF6
EC: PC: DEC = 1: 1: 2 92.7 Example 2 2,2,2-trifluoroethyl allylsulfonate 0.5 1M LiPF6
EC: PC: DEC = 1: 1: 2 84.2 Example 3 2,2,2-trifluoroethyl allylsulfonate 6.0 1M LiPF6
EC: PC: DEC = 1: 1: 2 91.7 Example 4 2,2,2-trifluoroethyl allylsulfonate 10 1M LiPF6
EC: PC: DEC = 1: 1: 2 89.1 Example 5 4-fluorophenyl
Allylsulfonate 2.0 1M LiPF6
EC: PC: DEC = 1: 1: 2 90.2 Comparative Example 1 - - 1M LiPF6
EC: PC: DEC = 1: 1: 2 73.2 Comparative Example 2 Ethyl allylsulfonate 2.0 1M LiPF6
EC: PC: DEC = 1: 1: 2 81.9

In Table 1, the batteries of Examples 1 to 5 using fluoroalkyl allylsulfonate derivatives as electrolyte additives according to the present invention exhibit higher discharge capacity retention rates compared to the batteries of Comparative Example 1 using electrolytes without addition of any compounds. Seemed. Further, according to the present invention, the batteries of Examples 1 to 5 using fluoroalkyl allylsulfonate derivatives as electrolyte additives had higher discharge capacity retention rates than those using the allylsulfonyl compound containing no fluorine (Comparative Example 2). Seemed.

When using an electrolyte solution containing an allylsulfonate derivative represented by the formula (1) having a halogen atom, preferably fluorine from the above, when using an electrolyte solution without addition of any compound or an allylsulfonate derivative containing no halogen atom It was found that a more stable SEI film was formed on the surface of the negative electrode when using an electrolyte solution containing a, thereby improving discharge capacity storage characteristics and lifetime characteristics of the battery.

Experimental Example 2 SEI Film Formation Confirmation Experiment on Cathode Surface

In order to confirm the formation of the SEI film on the surface of the negative electrode by the novel allylsulfonate derivative compound of the present invention, the following experiment was conducted.

The batteries prepared in Example 1 and Comparative Examples 1 to 2 were charged and discharged three times at 0.2 ° C. at 23 ° C. three times, and then, the batteries were disassembled in a discharged state to collect a negative electrode. Afterwards, 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 temperature is generally due to the thermal collapse of the SEI film formed on the surface of the cathode.

As a result, the negative electrode of the Example 1 battery using the allylsulfonate derivative compound represented by the formula (1) as an electrolyte solution component according to the present invention was higher than the negative electrode of the Comparative Example 1 battery using the electrolyte solution without any compound added thereto. Exothermic peak temperature was shown. This means that the negative electrode SEI membrane of the Example 1 battery using the allylsulfonate derivative compound has higher thermal stability than the negative electrode SEI membrane of the Comparative Example 1 battery using the electrolyte solution without adding any compound. In addition, the negative electrode of the battery of Example 1 showed a higher exothermic peak temperature than the negative electrode of the battery using the allylsulfonyl compound (Comparative Example 2) containing no fluorine.

When the electrolyte solution containing the allylsulfonate derivative compound represented by the formula (1) from the above, it was found that a more stable SEI film is formed on the surface of the negative electrode.

1 is a graph showing the results of differential scanning calorimetry (DSC) analysis according to Experimental Example 2. FIG.

Claims (10)

Allyl sulfonate derivative represented by the following formula (1). [Formula 1]

In formula 1, R is selected from the group consisting of an alkyl group having 1 to 20 carbon atoms containing at least one halogen atom, a cycloalkyl group having 3 to 8 carbon atoms including at least one halogen atom and a benzyl group containing at least one halogen atom; The halogen atom is selected from the group consisting of F, Cl, Br and I. An allylsulfonate derivative represented by the following Chemical Formula 1, which is prepared by reacting an allylsulfonyl halide compound and an alcohol compound including a halogen atom according to Scheme 1 below. Scheme 1

In Scheme 1, R is an alkyl group having 1 to 20 carbon atoms containing at least one halogen atom, a cycloalkyl group having 3 to 8 carbon atoms including at least one halogen atom, and an aryl having 6 to 12 carbon atoms including at least one halogen atom ) And a benzyl group containing one or more halogen atoms; X is selected from the group consisting of F, Cl, Br, and I; [Formula 1]

In Formula 1, R is an alkyl group having 1 to 20 carbon atoms including one or more halogen atoms, a cycloalkyl group having 3 to 8 carbon atoms including one or more halogen atoms, and an aryl having 6 to 12 carbon atoms including one or more halogen atoms ) And a benzyl group containing one or more halogen atoms; The halogen atom is selected from the group consisting of F, Cl, Br and I. An allylsulfonate derivative represented by Formula 1 below; Electrolyte solvents; And an electrolyte salt. [Formula 1]

In Formula 1, R is an alkyl group having 1 to 20 carbon atoms including one or more halogen atoms, a cycloalkyl group having 3 to 8 carbon atoms including one or more halogen atoms, and an aryl having 6 to 12 carbon atoms including one or more halogen atoms ) And a benzyl group containing one or more halogen atoms; The halogen atom is selected from the group consisting of F, Cl, Br and I. According to claim 3, wherein the allylsulfonate derivative represented by Formula 1 is fluoromethyl allylsulfonate, difluoromethyl allylsulfonate, trifluoromethyl allyl sulfonate, 2-fluoroethyl allylsulfonate, 2 , 2-difluoroethyl allylsulfonate, 2,2,2-trifluoroethyl allylsulfonate, pentafluoroethyl allylsulfonate, 3-fluoropropyl allylsulfonate, 3,3-difluoropropyl Allylsulfonate, 3,3,3-trifluoropropyl allylsulfonate, 2,2,3,3,3-pentafluoropropyl allylsulfonate, hexafluoroisopropyl allylsulfonate, 1H, 1H, 3H Hexafluorobutyl allylsulfonate, 2- (perfluorobutyl) ethyl allylsulfonate, 3- (perfluorobutyl) propyl allylsulfonate, 2- (perfluorohexyl) ethyl allylsulfonate, 3- (Perfluorohexyl) propyl allylsulfonate, 2- (perfluoro Octyl) ethyl allylsulfonate, 3- (perfluorooctyl) propyl allylsulfonate, 2- (perfluorodecyl) ethyl allylsulfonate, 3- (perfluorodecyl) propyl allylsulfonate, 4-fluoro Rophenyl allyl sulfonate, 3-fluorophenyl allyl sulfonate, 2,4-difluorophenyl allylsulfonate, pentafluorophenyl allylsulfonate, 4-fluorobenzyl allyl sulfonate, 3-fluorobenzyl allyl A nonaqueous electrolyte, characterized in that it is selected from the group consisting of sulfonates, 2,4-difluorobenzyl allylsulfonate, and pentafluorobenzyl allylsulfonate. The nonaqueous electrolyte of claim 3, wherein the content of the allylsulfonate derivative represented by Chemical Formula 1 is 0.1 to 20 parts by weight based on 100 parts by weight of the nonaqueous electrolyte. 4. The nonaqueous electrolyte of claim 3, wherein the electrolyte solvent is selected from the group consisting of cyclic carbonates, linear carbonates, lactones, ethers, esters, acetonitrile, lactams, ketones, and halogen derivatives thereof. The method of claim 3, wherein the electrolyte salt is (i) a cation selected from the group consisting of Li ⁺ , Na ⁺ and K ⁺ and ^{_{(ii) 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 - and _{C (CF 2 SO 2) 3} - is characterized by a non-aqueous electrolyte comprising a combination of an anion selected from the group consisting of. An electrode formed on part or all of a surface of a solid electrolyte interface (SEI) film including a reducing agent of an allylsulfonate derivative represented by Formula 1 below. [Formula 1]

In Formula 1, R is an alkyl group having 1 to 20 carbon atoms including one or more halogen atoms, a cycloalkyl group having 3 to 8 carbon atoms including one or more halogen atoms, and an aryl having 6 to 12 carbon atoms including one or more halogen atoms ) And a benzyl group containing one or more halogen atoms; The halogen atom is selected from the group consisting of F, Cl, Br and I. According to claim 8, wherein the allylsulfonate derivative represented by Formula 1 is fluoromethyl allylsulfonate, difluoromethyl allylsulfonate, trifluoromethyl allyl sulfonate, 2-fluoroethyl allylsulfonate, 2 , 2-difluoroethyl allylsulfonate, 2,2,2-trifluoroethyl allylsulfonate, pentafluoroethyl allylsulfonate, 3-fluoropropyl allylsulfonate, 3,3-difluoropropyl Allylsulfonate, 3,3,3-trifluoropropyl allylsulfonate, 2,2,3,3,3-pentafluoropropyl allylsulfonate, hexafluoroisopropyl allylsulfonate, 1H, 1H, 3H Hexafluorobutyl allylsulfonate, 2- (perfluorobutyl) ethyl allylsulfonate, 3- (perfluorobutyl) propyl allylsulfonate, 2- (perfluorohexyl) ethyl allylsulfonate, 3 -(Perfluorohexyl) propyl allylsulfonate, 2- (perfluoro Octyl) ethyl allylsulfonate, 3- (perfluorooctyl) propyl allylsulfonate, 2- (perfluorodecyl) ethyl allylsulfonate, 3- (perfluorodecyl) propyl allylsulfonate, 4-fluoro Phenyl allyl sulfonate, 3-fluorophenyl allyl sulfonate, 2,4-difluorophenyl allylsulfonate, pentafluorophenyl allylsulfonate, 4-fluorobenzyl allyl sulfonate, 3-fluorobenzyl allyl sulfo Nate, 2,4-difluorobenzyl allylsulfonate, and pentafluorobenzyl allylsulfonate. A secondary battery comprising a positive electrode, a negative electrode and a nonaqueous electrolyte, (i) the nonaqueous electrolyte solution according to any one of claims 3 to 7; or (ii) at least one of the positive electrode and the negative electrode comprises an electrode according to claim 8 or 9; or (iii) A secondary battery characterized in that both (i) and (ii) are applicable.

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