KR20080097599A - Additive for non-aqueous electrolyte and secondary battery using the same - Google Patents

Abstract

An additive for non-aqueous liquid electrolyte and a secondary battery using the same is provided to form an SEI film with superior thermal stability and lithium ion conductivity on the negative electrode surface by using a compound introduced with at least one electron withdrawing group and a silyl group as a electrolyte additive for forming the SEI film. An electrolyte including an electrolyte salt and electrolyte solvent comprises a compound introduced with at least one electron withdrawing group(EWG) and a silyl group, as a compound capable of forming the solid electrolyte interface(SEI) film on the negative electrode surface of a battery. The electrode is formed with the solid electrolyte interface(SEI) formed by electrical reduction of a compound introduced with at least one electron withdrawing group and a silyl group, on the part or whole of the surface.

Description

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

The present invention relates to an electrolyte solution capable of simultaneously improving high rate characteristics, high temperature performance, and lifespan performance of a secondary battery.

Recently, interest in energy storage technology is increasing. As the field of application extends to the energy of mobile phones, camcorders and notebook PCs, and even electric vehicles, efforts for research and development of electrochemical devices are becoming more concrete. The electrochemical device is the field attracting the most attention in this respect, and among them, the development of a secondary battery that can be charged and discharged has been the focus of attention.

Among the secondary batteries currently applied, lithium secondary batteries developed in the early 1990s generally have an average discharge voltage of about 3.6 to 3.7 V, resulting in higher operating voltage and higher energy density than conventional batteries such as Ni-MH and Ni-Cd. Has attracted much attention in that it is extremely large.

However, as the field of use of lithium secondary batteries gradually expands, battery performance improvement in various aspects such as high rate characteristics, cycle characteristics, and stability is required. For example, high-rate characteristics are indicative of the ability to charge and discharge high currents at high speeds, and are importantly evaluated in fields requiring high power such as power tools and hybrid electric vehicles (HEVs). Performance. However, a lithium secondary battery using a non-aqueous electrolyte has a problem in that its high rate characteristics are inferior because lithium ion conductivity is significantly lower than that of conventional batteries such as Ni-MH and Ni-Cd.

In addition, the non-aqueous electrolyte used in the secondary battery generally includes an electrolyte solvent and an electrolyte salt, the electrolyte solvent is decomposed at the electrode surface during charging and discharging of the battery, or is intercalated between the carbon material negative electrode layer to form a negative electrode structure. By collapsing, the stability of the battery can be impaired. 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 reduction of the electrolyte solvent during the initial charging of the battery, but generally the SEI film is a continuous Insufficient to serve as a protective film. Therefore, the above problem continues during battery charging and discharging, and thus there is a problem that the battery capacity is reduced or the battery life performance is lowered. In particular, the SEI film is not thermally stable and, when the battery is operated or left at a high temperature, is susceptible to collapse due to increased electrochemical energy and thermal energy over time. Therefore, there is a problem that the battery performance is further lowered under high temperature, in particular, gas such as CO ₂ is continuously generated due to the collapse of the SEI film, decomposition of the electrolyte, and the like, thereby increasing the internal pressure and thickness of the battery.

In order to solve the above-mentioned problems, EU 683537 and JP 1996-45545 describe the use of vinylene carbonate (VC) as an electrolyte additive capable of forming a solid electrolyte interface (SEI) film on the cathode surface. The method was presented. However, the SEI film formed by VC is rather large in resistance and easily collapses under high temperature, and thus does not improve the high rate characteristic and high temperature performance of the battery.

As described above, when a specific compound is added to an electrolyte solution to improve battery performance, the performance of some items is improved, but the performance of other items is often reduced, or only some items have been improved.

The inventors of the present invention use an electrolyte additive capable of forming a solid electrolyte interface (SEI) film on the surface of a negative electrode, and using a compound in which at least one electron attracting group (EWG) and a silyl group are introduced at the same time, high rate characteristics, high temperature performance, and room temperature of the battery. We found that we could improve performance at the same time.

The present invention is based on this.

The present invention relates to an electrolyte solution including an electrolyte salt and an electrolyte solvent, wherein the electrolyte solution is a compound capable of forming a solid electrolyte interface (SEI) film on the negative electrode surface of a battery, and at least one electron attracting group (EWG) and a silyl group are simultaneously used. An electrolyte further comprising an introduced compound; And it provides a secondary battery comprising the electrolyte solution.

In addition, the present invention provides an electrode having a solid electrolyte interface (SEI) film formed by electrical reduction of a compound into which one or more electron withdrawing groups (EWG) and silyl groups are simultaneously introduced; And it provides a secondary battery comprising the electrode.

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

In general, during initial charging of a secondary battery, an electrolyte solvent, such as a carbonate-based organic solvent, may react with lithium ions in the battery to form an SEI film on the surface of the negative electrode. The SEI film may not be porous and dense, resulting in repeated charging and discharging. Easy to collapse Such stability problems of the SEI film may degrade the performance of the battery. In particular, since the collapse of the SEI film is further accelerated at high temperatures, the high temperature performance of the battery is also a problem.

On the other hand, the SEI film acts as a resistance film to the movement of lithium ions to the negative electrode active material, it may interfere with the smooth movement of lithium. Therefore, the lithium ion conductivity of the battery may be reduced, and the high rate characteristic of the battery may be degraded.

Accordingly, various studies have been conducted to improve the characteristics of the SEI film using various electrolyte additives capable of forming the SEI film, but in most cases, the stability and the lithium ion conductivity of the SEI film were not simultaneously improved. For example, if a compound capable of forming a strong and dense SEI film is used as an electrolyte additive, the stability of the SEI film can be increased, but a thick SEI film is formed, which increases the resistance to the movement of lithium ions to the cathode active material. have. In other words, the stability of the SEI film and the lithium ion conductivity are in a mutually conflicting relationship.

The present invention is to solve the above problems, as a compound capable of forming an SEI film on the surface of the cathode by electrical reduction with an electrolyte additive, a compound in which at least one electron attracting group (EWG) and silyl group is introduced at the same time (hereinafter, Electrolyte solution additives).

Due to the above features, in the present invention, a thermally stable SEI film having excellent lithium ion conductivity may be formed, and further, high rate characteristics, high temperature performance, and room temperature performance of the battery may be simultaneously improved. The overall performance improvement of the battery can be estimated as follows, but is not limited thereto.

That is, the electrolyte additive of the present invention can be reduced at a lower potential by the introduction of an electron withdrawing group (EWG). Therefore, the SEI film may be formed on the surface of the negative electrode prior to the initial charge of the battery, and the SEI film may be regenerated earlier than the electrolyte solvent even when the SEI film is decayed over time or repeated charging and discharging. Therefore, in the present invention, a thermally stable SEI film may be formed, and the room temperature performance and the high temperature performance of the battery may be improved.

In addition, the SEI film formed by the electrical reduction of the electrolyte additive of the present invention includes a silyl group, the silyl group may act as an electrophile to facilitate the smooth movement of lithium ions between the negative electrode and the electrolyte. Therefore, the SEI film formed in the present invention has excellent lithium ion conductivity, thereby improving the high rate characteristic of the battery. In addition, the excellent lithium ion conductivity of the SEI film may reduce the internal resistance of the battery, thereby minimizing the decrease in electromotive force, thereby realizing a high voltage battery.

The compound that can be used as the electrolyte additive of the present invention is a compound capable of forming an SEI film on the surface of the cathode by electrical reduction, and can be used without limitation as long as it is a compound in which one or more electron withdrawing groups (EWG) and silyl groups are introduced at the same time. .

The compound may be a sulfinyl group-containing compound such as sulfone, sulfite, sulfonate, sultone, cyclic or linear carbonate-based compound, or lactam-based compound capable of forming an SEI film on the surface of the cathode through an electrical reduction reaction and a polymerization reaction. have.

On the other hand, the electron attracting group (EWG) is not limited as long as the electron withdrawing (electron withdrawing) action as known in the art, non-limiting examples thereof are halogen atoms (F, Cl, Br, I), cyano ( CN) group, nitro group (NO ₂ ), trifluoromethane (CF ₃ ) group, pentafluoroethane (C ₂ F ₅ ) group, trifluoromethane sulfonyl (SO ₂ CF ₃ ) group, pentafluoroethane sulfonyl ( SO ₂ C ₂ F ₅ ) group, trifluoromethane sulfonate (SO ₃ CF ₃ ) group, pentafluoroethane sulfonate (SO ₃ C ₂ F ₅ ) group, pentafluoro phenyl (C ₆ F ₅ ) group, acetyl ( COCH ₃ ) group, ethyl ketone (COC ₂ H ₅ ) group, propyl ketone (COC ₃ H ₇ ) group, butyl ketone (COC ₄ H ₉ ) group, pentyl ketone (COC ₅ H ₁₁ ) group, hexyl ketone (COC ₆ H ₁₃ ) group, ethane oate (CO ₂ CH ₃ ) group, propane oate (CO ₂ C ₂ H ₅ ) group, butane oate (CO ₂ C ₃ H ₇ ) group, pentanoate (CO ₂ C ₄ H ₉ ) group, and hexane oate (CO ₂ C ₅ H ₁₁ ) group. Moreover, the trimethylsilyl group is typical of the said silyl group.

In addition, the compound may include a compound of Formula 1 below, for example trimethylsilyl trifluoromethanesulfonate.

[Formula 1]

In Formula 1, R1 to R3 are each independently hydrogen, an alkyl group of C1-C6 or an alkenyl group of C2-C6, and X is an electron withdrawing group (EWG).

In the electrolyte solution provided by the present invention, the content of the compound may be adjusted according to the goal of improving the performance of the battery, but the content of the compound is preferably 0.01 to 10 parts by weight per 100 parts by weight of the electrolyte. When the amount is less than 0.01 parts by weight, the desired effect of improving the overall performance is insignificant. When it exceeds 10 parts by weight, the performance of the battery may be reduced due to the increase in the viscosity of the electrolyte.

The secondary battery electrolyte to which the compound is to be added includes conventional electrolyte components known in the art, such as electrolyte salts and electrolyte solvents.

Present in the secondary battery, the electrolytic solution provided by the invention uses the electrolytic possible salt is A ⁺ B ^- A salt of the structure, such as, A ⁺ is a Li ^+, Na ^+, an alkali metal cation or an ion composed of a combination thereof, such as K ⁺ It includes and 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 ^- , A salt containing ions consisting of anions such as C (CF ₂ SO ₂ ) ₃ ^- or a combination thereof, for example, LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y +1} SO ₂ Lithium salts (where x and y are natural numbers) can be used. In addition, the content of the electrolyte salt may be used in a conventional range known in the art, it may be used in a concentration of 0.8 to 2.0 M.

The electrolyte solvent may be a conventional organic solvent known in the art, such as cyclic or linear carbonates, esters, ethers, ketone organic solvents. Non-limiting examples of the solvent solvent is propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), dimethyl sulfoxide Said, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), butyrolactone, gamma butyrolactone (GBL), valerian Rolactone, caprolactone, fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate or halogen derivatives thereof Etc. These electrolyte solvents can be used individually or in mixture of 2 or more types.

The present invention also provides an electrode, preferably a cathode, on which a solid electrolyte interface (SEI) film formed by electrical reduction of a compound in which one or more electron withdrawing groups (EWG) and silyl groups are introduced simultaneously. The electrode may be prepared by charging and discharging an electrode manufactured according to a conventional method known in the art at least once in an electrolyte solution containing the electrolyte additive of the present invention to form an SEI film on the surface of the electrode active material of the electrode. In addition, before assembling the battery unit, an electrode prepared by forming an SEI film may be prepared by electrically reducing an electrode prepared according to a conventional method known in the art to an electrolyte solution containing the electrolyte additive of the present invention.

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. In this case, the binder may be suitably used in an amount of 1 to 10 by weight and the conductive material in an amount of 1 to 30 by weight based on the electrode active material.

The negative electrode active material may be a conventional negative electrode active material that can be used in the negative electrode of the conventional secondary battery, non-limiting examples of lithium metal, lithium alloy, carbon, petroleum coke that can store and release lithium ions , Activated carbon, graphite, carbon fiber, and the like. 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 and activated 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 negative electrode current collector include a foil made by copper, gold, nickel or a copper alloy or a combination thereof.

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).

Examples of the solvent include organic solvents such as NMP (N-methyl pyrrolidone), DMF (dimethyl formamide), acetone, and dimethyl acetamide or water, and these solvents may be used alone or in combination of two or more thereof. . The amount of the solvent used 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.

Furthermore, the secondary battery of the present invention is a part of the surface of the electrolyte solution containing a compound in which one or more electron withdrawing groups (EWG) and silyl groups are introduced at the same time, and / or a solid electrolyte interface (SEI) film formed by electrical reduction of the compound or It includes an electrode formed in all. Preferably, the present invention provides a separator, an anode, a cathode in which a solid electrolyte interface (SEI) film formed by electrical reduction of a compound into which at least one electron withdrawing group (EWG) and a silyl group is simultaneously introduced is formed on part or all of a surface thereof; And / or provides a secondary battery having an electrolyte solution containing the 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 may be manufactured in a form in which a positive electrode active material is bound to a positive electrode current collector according to a conventional method known in the art. 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 is not limited, but cans are cylindrical, coin-shaped, square or pouch types.

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

Example 1

Ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1: methane sulfonate (Trimethylsilyl trifluoromethanesulfonate) with trimethylsilyl trifluoroacetate in 1M LiPF ₆ solution in a volume ratio of 2 to prepare an electrolyte solution by adding 0.01 part by weight.

A polymer cell was prepared using LiCoO ₂ as a positive electrode and MAG-E as a negative electrode, and the electrolyte prepared above was injected thereto to prepare a lithium polymer battery in a conventional manner, and then aged at room temperature (RT) for 2 days, and Formation was performed for 50 minutes under 0.2C-rate and degas / reseal.

Example 2

Electrolyte solution in the same manner as in Example 1, except that 0.5 parts by weight of trimethylsilyl trifluoromethanesulfonate was added instead of 0.01 parts by weight; And a secondary battery.

Example 3

Electrolyte solution in the same manner as in Example 1 except that 1 part by weight of trimethylsilyl trifluoromethanesulfonate was added instead of 0.01 part by weight; And a secondary battery.

Example  4

Electrolyte solution in the same manner as in Example 1 except that 5 parts by weight of trimethylsilyl trifluoromethanesulfonate was added instead of 0.01 parts by weight; And a secondary battery.

Example 5

Electrolyte solution in the same manner as in Example 1, except that 10 parts by weight of trimethylsilyl trifluoromethane sulfonate was added instead of 0.01 parts by weight; And a secondary battery.

Comparative Example 1

Electrolyte solution in the same manner as in Example 1 except that trimethylsilyl benzenesulfonate was added instead of trimethylsilyl trifluoromethanesulfonate to prepare an electrolyte solution; And a secondary battery.

Comparative Example 2

Electrolyte solution in the same manner as in Example 1, except that no compound was added to the electrolyte solution; And a secondary battery.

Experimental Example 1. Evaluation of high rate characteristics of a lithium secondary battery

The batteries prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were charged at a constant voltage / constant of 4.2 V and 1 C-rate under 50 mA cut-off conditions at room temperature (RT), and then to 3.0 V at 1 C-rate. Constant current discharge was performed. In addition, the same conditions were charged, and constant current discharge was performed to 3.0 V at 0.2 C-rate.

The discharge capacity ratio of 1.0C to the measured discharge capacity of 0.2C is shown in Table 1, and the discharge capacity ratio is generally used as an evaluation value of the high rate characteristic of the battery.

Experimental Example 2 Evaluation of Room Temperature and High Temperature Performance of Lithium Secondary Battery

After charging and discharging the secondary batteries prepared in Examples 1 to 5 and Comparative Examples 1 and 2 400 times at room temperature (RT) and 45 ^° C., respectively, the measured results are shown in Table 1 below. At this time, it was charged with constant voltage / constant current of 4.2 V and 1 C-rate under 50 mA cut-off condition, and constant current discharge was performed up to 3.0 V with 1 C-rate. The ratio of the initial discharge capacity is expressed as a percentage.

TABLE 1

High rate characteristic (1.0C / 0.2C) Room temperature performance High temperature performance Example 1 92.6% 83% 61% Example 2 93.9% 88% 64% Example 3 94.8% 91% 72% Example 4 95.2% 93% 80% Example 5 94.9% 92% 80% Comparative Example 1 92.3% 82% 26% Comparative Example 2 91.1% 71% 42%

As a result, the battery of Comparative Example 1 using trimethylsilyl benzenesulfonate as an electrolyte additive showed improved results in terms of high rate characteristics and room temperature performance compared to the battery of Comparative Example 2, which did not use any electrolyte additive. Compared with Example 2, the results were significantly lower. On the other hand, the battery of Examples 1 to 5 using trimethylsilyl trifluoromethanesulfonate in which a silyl group and an electron withdrawing group (EWG) were simultaneously introduced as an electrolyte additive had a high rate characteristic and an improvement in room temperature performance. In addition, it showed about 1.5 to 2 times improvement compared to the battery of Comparative Example 2 in terms of high temperature performance.

From this, it can be seen that in the present invention, a thermally stable SEI film having excellent lithium ion conductivity can be formed, thereby improving high rate characteristics, high temperature performance, and room temperature performance of the battery at the same time.

According to the present invention, a compound in which at least one electron attracting group (EWG) and a silyl group are simultaneously introduced as an electrolyte additive for forming an SEI film may form an SEI film having excellent thermal stability and lithium ion conductivity on a cathode surface. Therefore, in the present invention, the high rate characteristic, room temperature performance, and high temperature performance of the battery may be improved at the same time.

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

Claims (13)

In an electrolyte solution comprising an electrolyte salt and an electrolyte solvent, the electrolyte solution is a compound capable of forming a solid electrolyte interface (SEI) film on the negative electrode surface of a battery, wherein at least one electron attracting group (EWG) and silyl group are introduced at the same time. Electrolyte further comprising. The method of claim 1, wherein the electron withdrawing group is halogen atom (F, Cl, Br, I), cyano (CN) group, nitro group (NO ₂ ), trifluoromethane (CF ₃ ) group, pentafluoroethane (C ₂ F ₅ ) group, trifluoro methane sulfonyl (SO ₂ CF ₃ ) group, pentafluoro ethane sulfonyl (SO ₂ C ₂ F ₅ ) group, trifluoro methane sulfonate (SO ₃ CF ₃ ) group, pentafur Orethane sulfonate (SO ₃ C ₂ F ₅ ) group, pentafluoro phenyl (C ₆ F ₅ ) group, alcetyl (COCH ₃ ) group, ethyl ketone (COC ₂ H ₅ ) group, propyl ketone (COC ₃ H ₍₇ ) group, butyl ketone (COC ₄ H ₉ ) group, pentyl ketone (COC ₅ H ₁₁ ) group, hexyl ketone (COC ₆ H ₁₃ ) group, ethane oate (CO ₂ CH ₃ ) group, propane oate (CO _{In the} group consisting of ₂ C ₂ H ₅ ) group, butane oate (CO ₂ C ₃ H ₇ ) group, pentane oate (CO ₂ C ₄ H ₉ ) group, and hexane oate (CO ₂ C ₅ H ₁₁ ) group An electrolyte solution characterized by being selected. The electrolyte of claim 1, wherein the silyl group is a trimethylsilyl group. The electrolyte of claim 1, wherein the compound is selected from the group consisting of sulfinyl group-containing compounds, cyclic carbonate-based compounds, linear carbonate-based compounds, and lactam-based compounds in which at least one electron withdrawing group (EWG) and a silyl group are introduced at the same time. . The electrolyte of claim 1, wherein the compound is a compound of Formula 1: [Formula 1]

In Formula 1, R1 to R3 are each independently hydrogen, an alkyl group of C1-C6 or an alkenyl group of C2-C6, and X is an electron withdrawing group (EWG). The electrolyte of claim 1, wherein the compound is present in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the electrolyte. An electrode in which a solid electrolyte interface (SEI) film formed by electrical reduction of a compound in which one or more electron withdrawing groups (EWG) and silyl groups are introduced simultaneously is formed on part or all of the surface. The electrode according to claim 7, wherein the compound is selected from the group consisting of a sulfinyl group-containing compound, a cyclic carbonate compound, a linear carbonate compound, and a lactam compound, in which at least one electron withdrawing group (EWG) and a silyl group are introduced at the same time. . 8. The electrode of claim 7, wherein the compound is a compound of Formula 1: [Formula 1]

In Formula 1, R1 to R3 are each independently hydrogen, an alkyl group of C1-C6 or an alkenyl group of C2-C6, and X is an electron withdrawing group (EWG). The secondary battery containing the electrolyte solution in any one of Claims 1-6. The secondary battery according to claim 10, which is a lithium secondary battery. The secondary battery containing the electrode of Claims 7-9. The secondary battery according to claim 12, which is a lithium secondary battery.