KR20230089230A - Electrolyte for lithium secondary battery and lithium secondary battery including thereof - Google Patents

Abstract

The present invention relates to an electrolyte for a lithium secondary battery and a lithium secondary battery including the same. Provided is a lithium secondary battery having an excellent lifespan even when applying high voltage, high rates, and high temperature by including a fluorinated anhydride as an additive. The electrolyte for a lithium secondary battery including lithium salt and an organic solvent includes a compound that satisfies chemical formula 1.

Description

Electrolyte for lithium secondary battery and lithium secondary battery containing the same {Electrolyte for lithium secondary battery and lithium secondary battery including its}

The present invention relates to a method for providing a lithium secondary battery having excellent lifespan and improved safety even when a high voltage and high rate is applied by including an electrolyte solution containing fluorinated anhydride (anhydride).

A lithium secondary battery has a mechanism in which lithium ions from a lithium metal oxide, which is a positive electrode, move to a carbon electrode, which is a negative electrode, and are inserted into carbon during initial charging. At this time, due to the strong reactivity of lithium, the surface of the carbon particles, which is an anode active material, and the surface of lithium metal oxide, which is a cathode active material, react with the electrolyte to form a film called SEI (Solid Electrolyte Interphase) on the surface of the anode.

This SEI is one of the core mechanisms of a lithium secondary battery using an electrolyte, and serves to prevent further decomposition of the electrolyte while protecting the negative electrode.

In the case of the cathode, there are sufficiently many studies on the above-mentioned SEI, but in the case of the cathode, there are fewer studies than the cathode SEI. It is known that structural collapse can be prevented.

However, the higher the performance of the lithium secondary battery, that is, the higher the voltage, high rate (high current density applied for fast charging) and exposure to the harsh environment of high temperature, the chemical structural instability and interface instability of cathode and anode materials become more prominent. , In addition, the problem of fire risk due to thermal runaway has emerged, and finding materials and technologies that improve stability and safety to solve this problem can be said to be a major challenge currently facing lithium secondary batteries.

Therefore, the inventors of the present invention invented an electrolyte solution capable of improving the high voltage, high rate, and high temperature characteristics of a lithium secondary battery while maintaining the large frame of the positive electrode, negative electrode, and non-aqueous organic electrolyte solution widely used in the art, and the present invention To provide an electrolyte capable of providing a lithium secondary battery with excellent lifespan characteristics even when a high voltage, high rate, and high temperature is applied.

(0001) Republic of Korea Patent Registration No. 10-2028647 (2017. 04. 07.) (0002) Republic of Korea Patent Publication No. 10-2020-0037612 (2020. 04. 09.) (0003) Japanese Unexamined Patent Publication No. 2013-2114224 (October 10, 2013)

In order to solve the above problems, an object of the present invention is to provide an electrolyte solution containing fluorinated anhydride (anhydride) and a lithium secondary battery including the same.

One aspect of the present invention for achieving the above object relates to an electrolyte solution for a lithium secondary battery containing a fluorinated anhydride (anhydride).

In the above aspect, the electrolyte solution for a lithium secondary battery may include a lithium salt and an organic solvent.

In the above aspect, the electrolyte solution for a lithium secondary battery may include a compound satisfying Formula 1 below.

[Formula 1]

(In Formula 1 above,

R ₁ and R ₂ are each independently C1 to C4 alkyl or C1 to C4 fluorinated alkyl, but at least one of R ₁ and R ₂ includes fluorine.)

In the above aspect, the organic solvent may include a compound satisfying Formula 2 below.

[Formula 2]

(In Formula 2 above,

R ₁ and R ₂ are independently of each other CH ₃ or CH _x F _3-x (x is an integer from 0 to 3),

m and n are integers from 1 to 3 that are independent of each other.)

In the above aspect, the organic solvent may include a compound satisfying Formula 3 below.

[Formula 3]

(In Formula 3,

R ₁ and R ₂ are independently of each other CH ₃ or CH _x F _3-x (x is an integer from 0 to 3),

m and n are integers from 1 to 3 that are independent of each other.)

In the above aspect, the organic solvent may include a compound satisfying Formula 4 below.

[Formula 4]

(In Chemical Formula 4,

X ₁ and X ₂ are each independently H, F, CH ₃ or CH _x F _3-x (x is an integer from 0 to 2).)

In the above aspect, the electrolyte solution for a lithium secondary battery may contain 0.01 to 5 parts by weight of a compound satisfying Formula 1 based on 100 parts by weight of a mixture of the lithium salt and the organic solvent.

In the above aspect, the concentration of the lithium salt in the electrolyte solution for a lithium secondary battery may be 0.1 to 20M.

In the above aspect, the electrolyte solution for a lithium secondary battery may be flame retardant or nonflammable because the self-extinguishing time (SET) is less than 20 s·g ⁻¹ .

In addition, another aspect of the present invention relates to a lithium secondary battery including the electrolyte solution for the lithium secondary battery.

In the other aspect, the lithium secondary battery is an electrolyte solution for a lithium secondary battery; anode; cathode; And a separator; may be one containing.

In the case of the electrolyte solution for a lithium secondary battery containing a fluorinated anhydride (anhydride) according to the present invention, there is an improvement in that it has excellent long life even when a high rate and a high voltage are applied.

1 is a Nyquist plot showing electrochemical impedances of Example 1 and Comparative Example 1.
Figure 2 is a Nyquist diagram showing the electrochemical impedance of Example 2 and Comparative Example 3.

Hereinafter, an electrolyte solution for a lithium secondary battery according to the present invention and a lithium secondary battery including the same will be described in detail. The drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented below, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, if there is no other definition in the technical terms and scientific terms used in the present invention, they have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and in the following description and accompanying drawings, the present invention Descriptions of well-known functions and configurations that may unnecessarily obscure the gist of will be omitted.

The electrolyte solution for a lithium secondary battery provided in the present invention may include a compound satisfying Formula 1 below.

[Formula 1]

(In Formula 1 above,

R ₁ and R ₂ are each independently C1 to C4 alkyl or C1 to C4 fluorinated alkyl, but at least one of R ₁ and R ₂ includes fluorine.)

At this time, R ₁ and R ₂ are each independently C _n H _m F _{(2n + 1-m)} (m, n is preferably each n is an integer of 1 to 4, m is an integer of 0 to 9), More preferably, n is 2 to 4 and m is 0.

The compound satisfying Formula 1 is specifically,

Acetic fluoroacetic anhydride, acetic difluoroacetic anhydride, fluoroacetic anhydride, trifluoroacetic anhydride, acetic 2-fluoropropionic anhydride, Acetic 3-fluoropropionic anhydride, acetic 2,2-difluoropropionic anhydride, acetic 2,3-difluoropropionic anhydride, acetic 3,3-difluoro Lopropionic anhydride, acetic 2,2,3-trifluoropropionic anhydride, acetic 2,3,3-trifluoropropionic anhydride, acetic 3,3,3-tri Fluoropropionic anhydride, acetic 2,2,3,3-tetrafluoropropionic anhydride, acetic 2,3,3,3-tetrafluoropropionic anhydride, acetic pentafluoro Ropropionic anhydride, fluoroacetic 2-fluoropropionic anhydride, fluoroacetic 3-fluoropropionic anhydride, fluoroacetic 2,2-difluoropropionic anhydride Ride, fluoroacetic 2,3-difluoropropionic anhydride, fluoroacetic 3,3-difluoropropionic anhydride, fluoroacetic 2,2,3-trifluoropropy Onyx Anhydride, Fluoroacetic 2,3,3-Trifluoropropionic Anhydride, Fluoroacetic 3,3,3-Trifluoropropionic Anhydride, Fluoroacetic 2,2 ,3,3-tetrafluoropropionic anhydride, fluoroacetic 2,3,3,3-tetrafluoropropionic anhydride, fluoroacetic pentafluoropropionic anhydride, difluoro Roacetic 2-fluoropropionic anhydride, difluoroacetic 3-fluoropropionic anhydride, difluoroacetic 2,2-difluoropropionic anhydride, difluoroacetic Tick 2,3-difluoropropionic anhydride, difluoroacetic 3,3-difluoropropionic anhydride, difluoroacetic 2,2,3-trifluoropropionic anhydride Ride, difluoroacetic 2,3,3-trifluoropropionic anhydride, difluoroacetic 3,3,3-trifluoropropionic anhydride, difluoroacetic 2,2 ,3,3-tetrafluoropropionic anhydride, difluoroacetic 2,3,3,3-tetrafluoropropionic anhydride, difluoroacetic pentafluoropropionic anhydride, Trifluoroacetic 2-fluoropropionic anhydride, trifluoroacetic 3-fluoropropionic anhydride, trifluoroacetic 2,2-difluoropropionic anhydride, trifluoro Roacetic 2,3-difluoropropionic anhydride, trifluoroacetic 3,3-difluoropropionic anhydride, trifluoroacetic 2,2,3-trifluoropropionic Anhydride, trifluoroacetic 2,3,3-trifluoropropionic anhydride, trifluoroacetic 3,3,3-trifluoropropionic anhydride, trifluoroacetic 2 ,2,3,3-tetrafluoropropionic anhydride, trifluoroacetic 2,3,3,3-tetrafluoropropionic anhydride, trifluoroacetic pentafluoropropionic anhydride Ride, propionic 2-fluoropropionic anhydride, propionic 3-fluoropropionic anhydride, propionic 2,2-difluoropropionic anhydride, propionic 2,3-difluoro Propionic Anhydride, Propionic 3,3-Difluoropropionic Anhydride, Propionic 2,2,3-Trifluoropropionic Anhydride, Propionic 2,3,3-Trifluoropropy Onic Anhydride, Propionic 3,3,3-Trifluoropropionic Anhydride, Propionic 2,2,3,3-Tetrafluoropropionic Anhydride, Propionic 2,3,3,3 -Tetrafluoropropionic anhydride, propionic pentafluoropropionic anhydride, 2-fluoropropionic anhydride, 2-fluoropropionic 3-fluoropropionic anhydride, 2-fluoro Ropropionic 2,2-difluoropropionic anhydride, 2-fluoropropionic 2,3-difluoropropionic anhydride, 2-fluoropropionic 3,3-difluoropropionic Anhydride, 2-fluoropropionic 2,2,3-trifluoropropionic anhydride, 2-fluoropropionic 2,3,3-trifluoropropionic anhydride, 2-fluoro Propionic 3,3,3-trifluoropropionic anhydride, 2-fluoropropionic 2,2,3,3-tetrafluoropropionic anhydride, 2-fluoropropionic 2,3, 3,3-tetrafluoropropionic anhydride, 2-fluoropropionic pentafluoropropionic anhydride, 3-fluoropropionic 2-fluoropropionic anhydride, 3-fluoropropionic Anhydride, 3-fluoropropionic 2,2-difluoropropionic anhydride, 3-fluoropropionic 2,3-difluoropropionic anhydride, 3-fluoropropionic 3, 3-difluoropropionic anhydride, 3-fluoropropionic 2,2,3-trifluoropropionic anhydride, 3-fluoropropionic 2,3,3-trifluoropropionic anhydride Hydride, 3-fluoropropionic 3,3,3-trifluoropropionic anhydride, 3-fluoropropionic 2,2,3,3-tetrafluoropropionic anhydride, 3-fluoro Ropropionic 2,3,3,3-tetrafluoropropionic anhydride, 3-fluoropropionic pentafluoropropionic anhydride, 2,2-difluoropropionic 2-fluoropropionic Anhydride, 2,2-difluoropropionic 3-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2,2-difluoropropionic 2,3-di Fluoropropionic anhydride, 2,2-difluoropropionic 3,3-difluoropropionic anhydride, 2,2-difluoropropionic 2,2,3-trifluoropropionic Anhydride, 2,2-difluoropropionic 2,3,3-trifluoropropionic anhydride, 2,2-difluoropropionic 3,3,3-trifluoropropionic anhydride Ride, 2,2-difluoropropionic 2,2,3,3-tetrafluoropropionic anhydride, 2,2-difluoropropionic 2,3,3,3-tetrafluoropropionic Anhydride, 2,2-difluoropropionic pentafluoropropionic anhydride, 2,3-difluoropropionic 2-fluoropropionic anhydride, 2,3-difluoropropionic 3-fluoropropionic anhydride, 2,3-difluoropropionic 2,2-difluoropropionic anhydride, 2,3-difluoropropionic 2,3-difluoropropionic Anhydride, 2,3-difluoropropionic 3,3-difluoropropionic anhydride, 2,3-difluoropropionic 2,2,3-trifluoropropionic anhydride, 2,3-difluoropropionic 2,3,3-trifluoropropionic anhydride, 2,3-difluoropropionic 3,3,3-trifluoropropionic anhydride, 2, 3-difluoropropionic 2,2,3,3-tetrafluoropropionic anhydride, 2,3-difluoropropionic 2,3,3,3-tetrafluoropropionic anhydride, 2,3-difluoropropionic pentafluoropropionic anhydride, 3,3-difluoropropionic 2-fluoropropionic anhydride, 3,3-difluoropropionic 3-fluoro Propionic anhydride, 3,3-difluoropropionic 2,2-difluoropropionic anhydride, 3,3-difluoropropionic 2,3-difluoropropionic anhydride, 3,3-difluoropropionic 3,3-difluoropropionic anhydride, 3,3-difluoropropionic 2,2,3-trifluoropropionic anhydride, 3,3- Difluoropropionic 2,3,3-trifluoropropionic anhydride, 3,3-difluoropropionic 3,3,3-trifluoropropionic anhydride, 3,3-difluoro Ropropionic 2,2,3,3-tetrafluoropropionic anhydride, 3,3-difluoropropionic 2,3,3,3-tetrafluoropropionic anhydride, 3,3- Difluoropropionic pentafluoropropionic anhydride, 2,2,3-trifluoropropionic 2-fluoropropionic anhydride, 2,2,3-trifluoropropionic 3-fluoro Propionic anhydride, 2,2,3-trifluoropropionic 2,2-difluoropropionic anhydride, 2,2,3-trifluoropropionic 2,3-difluoropropionic Anhydride, 2,2,3-trifluoropropionic 3,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic 2,2,3-trifluoropropionic Anhydride, 2,2,3-trifluoropropionic 2,3,3-trifluoropropionic anhydride, 2,2,3-trifluoropropionic 3,3,3-trifluoro Propionic anhydride, 2,2,3-trifluoropropionic 2,2,3,3-tetrafluoropropionic anhydride, 2,2,3-trifluoropropionic 2,3,3 ,3-Tetrafluoropropionic anhydride, 2,2,3-trifluoropropionic pentafluoropropionic anhydride, 2,3,3-trifluoropropionic 2-fluoropropionic anhydride hydride, 2,3,3-trifluoropropionic 3-fluoropropionic anhydride, 2,3,3-trifluoropropionic 2,2-difluoropropionic anhydride, 2, 3,3-trifluoropropionic 2,3-difluoropropionic anhydride, 2,3,3-trifluoropropionic 3,3-difluoropropionic anhydride, 2,3, 3-trifluoropropionic 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic 2,3,3-trifluoropropionic anhydride, 2, 3,3-trifluoropropionic 3,3,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic 2,2,3,3-tetrafluoropropionic anhydride Ride, 2,3,3-trifluoropropionic 2,3,3,3-tetrafluoropropionic anhydride, 2,3,3-trifluoropropionic pentafluoropropionic anhydride, 3,3,3-trifluoropropionic 2-fluoropropionic anhydride, 3,3,3-trifluoropropionic 3-fluoropropionic anhydride, 3,3,3-trifluoro Lopropionic 2,2-difluoropropionic anhydride, 3,3,3-trifluoropropionic 2,3-difluoropropionic anhydride, 3,3,3-trifluoropropy Onyx 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic 2,2,3-trifluoropropionic anhydride, 3,3,3-trifluoropropi Onyx 2,3,3-trifluoropropionic anhydride, 3,3,3-trifluoropropionic 3,3,3-trifluoropropionic anhydride, 3,3,3-trifluoro Lopropionic 2,2,3,3-tetrafluoropropionic anhydride, 3,3,3-trifluoropropionic 2,3,3,3-tetrafluoropropionic anhydride, 3, 3,3-trifluoropropionic pentafluoropropionic anhydride, 2,2,3,3-tetrafluoropropionic 2-fluoropropionic anhydride, 2,2,3,3-tetra Fluoropropionic 3-fluoropropionic anhydride, 2,2,3,3-tetrafluoropropionic 2,2-difluoropropionic anhydride, 2,2,3,3-tetrafluoro Ropropionic 2,3-difluoropropionic anhydride, 2,2,3,3-tetrafluoropropionic 3,3-difluoropropionic anhydride, 2,2,3,3- tetrafluoropropionic 2,2,3-trifluoropropionic anhydride, 2,2,3,3-tetrafluoropropionic 2,3,3-trifluoropropionic anhydride, 2, 2,3,3-tetrafluoropropionic 3,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrafluoropropionic 2,2,3,3-tetrafluoro Propionic anhydride, 2,2,3,3-tetrafluoropropionic 2,3,3,3-tetrafluoropropionic anhydride, 2,2,3,3-tetrafluoropropionic penta Fluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic 2-fluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic 3-fluoropropionic Anhydride, 2,3,3,3-tetrafluoropropionic 2,2-difluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic 2,3-difluoro Propionic anhydride, 2,3,3,3-tetrafluoropropionic 3,3-difluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic 2,2,3 -Trifluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic 2,3,3-trifluoropropionic anhydride, 2,3,3,3-tetrafluoropropy Onyx 3,3,3-trifluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic 2,2,3,3-tetrafluoropropionic anhydride, 2,3, 3,3-tetrafluoropropionic 2,3,3,3-tetrafluoropropionic anhydride, 2,3,3,3-tetrafluoropropionic pentafluoropropionic anhydride, pentafluoro Ropropionic 2-fluoropropionic anhydride, pentafluoropropionic 3-fluoropropionic anhydride, pentafluoropropionic 2,2-difluoropropionic anhydride, pentafluoropropionic Onyx 2,3-difluoropropionic anhydride, pentafluoropropionic 3,3-difluoropropionic anhydride, pentafluoropropionic 2,2,3-trifluoropropionic anhydride Ride, pentafluoropropionic 2,3,3-trifluoropropionic anhydride, pentafluoropropionic 3,3,3-trifluoropropionic anhydride, pentafluoropropionic 2,2 Selected from the group consisting of 3,3-tetrafluoropropionic anhydride, pentafluoropropionic 2,3,3,3-tetrafluoropropionic anhydride and pentafluoropropionic anhydride it may be

The electrolyte solution for a lithium secondary battery provided in the present invention may include a lithium salt and an organic solvent.

The lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiC ₆ H ₅ SO ₃ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ . LiN(FSO ₂ ) ₂ , LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ) (x, y are 0 or natural numbers), LiCl, LiI, LiSCN, LiB(C ₂ O ₄ ) ₂ , LiF ₂ BC ₂ O ₄ , LiPF ₄ (C ₂ O ₄ ), LiPF ₂ (C ₂ O ₄ ) ₂ , and LiP (C ₂ O ₄ ) ₃ Any one selected from the group consisting of; It may be a mixture of two or more, which is only one example and can be used without particular limitation as long as it is commonly used in the art and is not necessarily limited thereto.

The organic solvent may include a compound satisfying Formula 2 below.

[Formula 2]

(In Formula 2 above,

R ₁ and R ₂ are independently of each other CH ₃ or CH _x F _3-x (x is an integer from 0 to 3),

m and n are mutually independent integers from 0 to 3.)

For example, compounds satisfying Formula 2 include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, 2-fluoromethyl methyl carbonate and 2-fluoroethyl methyl carbonate, methyl (2,2,2-trifluoro There are linear carbonate-based materials and linear fluorinated carbonate-based materials such as ethyl) carbonate and di-2,2,2-trifluoroethyl carbonate.

The organic solvent may include a compound satisfying Formula 3 below.

[Formula 3]

(In Formula 3,

R ₁ and R ₂ are independently of each other CH ₃ or CH _x F _3-x (x is an integer from 0 to 3),

m and n are mutually independent integers from 0 to 3.)

For example, compounds satisfying Formula 3 include methyl acetate, methyl propionate, ethyl acetate, 2,2,2-trifluoroethyl acetate, 2,2-difluoroethyl acetate, 2-fluoro There are linear ester-based and linear fluorinated ester-based materials such as ethyl acetate, trifluoromethyl acetate, difluoromethyl acetate, fluoro methyl acetate and 2,2,2-trifluoroethyl propionate.

The organic solvent may include a compound satisfying Formula 4 below.

[Formula 4]

(In Chemical Formula 4,

X ₁ and X ₂ are each independently H, F, CH ₃ or CH _x F _3-x (x is an integer from 0 to 2).)

For example, the compound satisfying Chemical Formula 4 includes cyclic carbonate-based materials such as ethylene carbonate, propylene carbonate, fluoroethylene carbonate, and 4,4-difluoroethylene carbonate, and fluorinated cyclic carbonate-based materials.

The electrolyte solution for a lithium secondary battery may further include organic solvents other than compounds satisfying Chemical Formulas 2 to 4. Specifically, dimethyl ether, ethylmethyl ether, diethyl ether, propylmethyl ether, propylethyl ether, dipropyl ether, isopropylmethyl ether, isopropylethyl ether, diisopropyl ether, n-butylmethyl ether, n-butyl Ethyl ether, n-butylpropyl ether, n-butylisopropyl ether, n-dibutyl ether, tert-butylmethyl ether, tert-butylethyl ether, tert-butylpropyl ether, tert-butylisopropyl ether, tert-di Butyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol tert-butyl ether, diethylene glycol ether, propylene glycol methyl ether, propylene glycol Ether groups such as ethyl ether, propylene glycol propyl ether, propylene glycol isopropyl ether, propylene glycol n-butyl ether, propylene glycol tert-butyl ether, and dipropylene glycol ether; Fluoromethyl methyl ether, difluoromethyl methyl ether, trifluoromethyl methyl ether, di(fluoromethyl) ether, difluoromethyl fluoromethyl ether, trifluoromethyl fluoromethyl ether, di(difluoro methyl) ether, trifluoromethyl difluoromethyl ether, di(trifluoromethyl) ether, 1-fluoroethyl methyl ether, 2-fluoroethyl methyl ether, 1,1-difluoroethyl methyl ether , 1,2-difluoroethyl methyl ether, 2,2-difluoroethyl methyl ether, 1,1,1-trifluoroethyl methyl ether, 1,1,2-trifluoroethyl methyl ether, 1 ,2,2-trifluoroethyl methyl ether, 2,2,2-trifluoroethyl methyl ether, 1,1,1,2-tetrafluoroethyl methyl ether, 1,1,2,2-tetrafluoro Roethyl methyl ether, 1,2,2,2-tetrafluoroethyl methyl ether, pentafluoroethyl methyl ether, 1,1,2,2,2-pentafluoroethyl methyl ether, hexafluoroethyl methyl ether , 1-fluoroethyl fluoromethyl ether, 2-fluoroethyl fluoromethyl ether, 1,1-difluoroethyl fluoromethyl ether, 1,2-difluoroethyl fluoromethyl ether, 2,2 -difluoroethyl fluoromethyl ether, 1,1,1-trifluoroethyl fluoromethyl ether, 1,1,2-trifluoroethyl fluoromethyl ether, 1,2,2-trifluoroethyl Fluoromethyl ether, 2,2,2-trifluoroethyl fluoromethyl ether, 1,1,1,2-tetrafluoroethyl fluoromethyl ether, 1,1,2,2-tetrafluoroethyl fluoro Romethyl ether, 1,2,2,2-tetrafluoroethyl fluoromethyl ether, pentafluoroethyl fluoromethyl ether, 1,1,2,2,2-pentafluoroethyl fluoromethyl ether, hexa Fluoroethyl fluoromethyl ether, 1-fluoroethyl difluoromethyl ether, 2-fluoroethyl difluoromethyl ether, 1,1-difluoroethyl difluoromethyl ether, 1,2-difluoro Roethyl difluoromethyl ether, 2,2-difluoroethyl difluoromethyl ether, 1,1,1-trifluoroethyl difluoromethyl ether, 1,1,2-trifluoroethyl difluoro Romethyl ether, 1,2,2-trifluoroethyl difluoromethyl ether, 2,2,2-trifluoroethyl difluoromethyl ether, 1,1,1,2-tetrafluoroethyl difluoro Romethyl ether, 1,1,2,2-tetrafluoroethyl difluoromethyl ether, 1,2,2,2-tetrafluoroethyl difluoromethyl ether, pentafluoroethyl difluoromethyl ether, 1,1,2,2,2-pentafluoroethyl difluoromethyl ether, hexafluoroethyl difluoromethyl ether, 1-fluoroethyl trifluoromethyl ether, 2-fluoroethyl trifluoromethyl Ether, 1,1-difluoroethyl trifluoromethyl ether, 1,2-difluoroethyl trifluoromethyl ether, 2,2-difluoroethyl trifluoromethyl ether, 1,1,1- Trifluoroethyl trifluoromethyl ether, 1,1,2-trifluoroethyl trifluoromethyl ether, 1,2,2-trifluoroethyl trifluoromethyl ether, 2,2,2-trifluoro Roethyl trifluoromethyl ether, 1,1,1,2-tetrafluoroethyl trifluoromethyl ether, 1,1,2,2-tetrafluoroethyl trifluoromethyl ether, 1,2,2, 2-tetrafluoroethyl trifluoromethyl ether, pentafluoroethyl trifluoromethyl ether, 1,1,2,2,2-pentafluoroethyl trifluoromethyl ether, hexafluoroethyl trifluoromethyl Ether, 1-fluoroethyl ethyl ether, 2-fluoroethyl ethyl ether, 1,1-difluoroethyl ethyl ether, 1,2-difluoroethyl ethyl ether, 2,2-difluoroethyl ethyl ether , 1,1,1-trifluoroethyl ethyl ether, 1,1,2-trifluoroethyl ethyl ether, 1,2,2-trifluoroethyl ethyl ether, 2,2,2-trifluoroethyl Ethyl ether, 1,1,1,2-tetrafluoroethyl ethyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,2,2,2-tetrafluoroethyl ethyl ether, pentafluoro Roethyl ethyl ether, 1,1,2,2,2-pentafluoroethyl ethyl ether, hexafluoroethyl ethyl ether, 1-fluoroethyl 1-fluoroethyl ether, 2-fluoroethyl 1-fluoroethyl Ether, 1,1-difluoroethyl 1-fluoroethyl ether, 1,2-difluoroethyl 1-fluoroethyl ether, 2,2-difluoroethyl 1-fluoroethyl ether, 1,1 , 1-trifluoroethyl 1-fluoroethyl ether, 1,1,2-trifluoroethyl 1-fluoroethyl ether, 1,2,2-trifluoroethyl 1-fluoroethyl ether, 2, 2,2-trifluoroethyl 1-fluoroethyl ether, 1,1,1,2-tetrafluoroethyl 1-fluoroethyl ether, 1,1,2,2-tetrafluoroethyl 1-fluoro Ethyl ether, 1,2,2,2-tetrafluoroethyl 1-fluoroethyl ether, pentafluoroethyl 1-fluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 1-fluoro Roethyl ether, hexafluoroethyl 1-fluoroethyl ether, 1-fluoroethyl 2-fluoroethyl ether, 2-fluoroethyl 2-fluoroethyl ether, 1,1-difluoroethyl 2-fluoro Roethyl ether, 1,2-difluoroethyl 2-fluoroethyl ether, 2,2-difluoroethyl 2-fluoroethyl ether, 1,1,1-trifluoroethyl 2-fluoroethyl ether , 1,1,2-trifluoroethyl 2-fluoroethyl ether, 1,2,2-trifluoroethyl 2-fluoroethyl ether, 2,2,2-trifluoroethyl 2-fluoroethyl Ether, 1,1,1,2-tetrafluoroethyl 2-fluoroethyl ether, 1,1,2,2-tetrafluoroethyl 2-fluoroethyl ether, 1,2,2,2-tetrafluoro Roethyl 2-fluoroethyl ether, pentafluoroethyl 2-fluoroethyl ether, pentafluoroethyl 2-fluoroethyl ether, hexafluoroethyl 2-fluoroethyl ether, 1-fluoroethyl 1,2 -Difluoroethyl ether, 2-fluoroethyl 1,2-difluoroethyl ether, 1,1-difluoroethyl 1,2-difluoroethyl ether, di(1,2-difluoroethyl ) ether, 2,2-difluoroethyl 1,2-difluoroethyl ether, 1,1,1-trifluoroethyl 1,2-difluoroethyl ether, 1,1,2-trifluoro Ethyl 1,2-difluoroethyl ether, 1,2,2-trifluoroethyl 1,2-difluoroethyl ether, 2,2,2-trifluoroethyl 1,2-difluoroethyl ether , 1,1,1,2-tetrafluoroethyl 1,2-difluoroethyl ether, 1,1,2,2-tetrafluoroethyl 1,2-difluoroethyl ether, 1,2,2 ,2-tetrafluoroethyl 1,2-difluoroethyl ether, pentafluoroethyl 1,2-difluoroethyl ether, pentafluoroethyl 1,2-difluoroethyl ether, hexafluoroethyl 1 ,2-difluoroethyl ether, 1,1-difluoroethyl 2,2-difluoroethyl ether, 1,2-difluoroethyl 2,2-difluoroethyl ether, di(2,2 -difluoroethyl) ether, 1,1,1-trifluoroethyl 2,2-difluoroethyl ether, 1,1,2-trifluoroethyl 2,2-difluoroethyl ether, 1, 2,2-trifluoroethyl 2,2-difluoroethyl ether, 2,2,2-trifluoroethyl 2,2-difluoroethyl ether, 1,1,1,2-tetrafluoroethyl 2,2-difluoroethyl ether, 1,1,2,2-tetrafluoroethyl 2,2-difluoroethyl ether, 1,2,2,2-tetrafluoroethyl 2,2-difluoro Roethyl ether, pentafluoroethyl 2,2-difluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 2,2-difluoroethyl ether, hexafluoroethyl 2,2- Difluoroethyl ether, 1,1-difluoroethyl 1,1,1-trifluoroethyl ether, 1,2-difluoroethyl 1,1,1-trifluoroethyl ether, 2,2- Difluoroethyl 1,1,1-trifluoroethyl ether, di(1,1,1-trifluoroethyl) ether, 1,1,2-trifluoroethyl 1,1,1-trifluoro Ethyl ether, 1,2,2-trifluoroethyl 1,1,1-trifluoroethyl ether, 2,2,2-trifluoroethyl 1,1,1-trifluoroethyl ether, 1,1 ,1,2-tetrafluoroethyl 1,1,1-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl 1,1,1-trifluoroethyl ether, 1,2,2 ,2-tetrafluoroethyl 1,1,1-trifluoroethyl ether, pentafluoroethyl 1,1,1-trifluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 1 ,1,1-trifluoroethyl ether, hexafluoroethyl 1,1,1-trifluoroethyl ether, 1,1-difluoroethyl 1,1,2-trifluoroethyl ether, 1,2 -Difluoroethyl 1,1,2-trifluoroethyl ether, 2,2-difluoroethyl 1,1,2-trifluoroethyl ether, 1,1,1-trifluoroethyl 1,1 ,2-trifluoroethyl ether, 1,1,2-trifluoroethyl 1,1,2-trifluoroethyl ether, 1,2,2-trifluoroethyl 1,1,2-trifluoro Ethyl ether, 2,2,2-trifluoroethyl 1,1,2-trifluoroethyl ether, 1,1,1,2-tetrafluoroethyl 1,1,2-trifluoroethyl ether, 1 ,1,2,2-tetrafluoroethyl 1,1,2-trifluoroethyl ether, 1,2,2,2-tetrafluoroethyl 1,1,2-trifluoroethyl ether, pentafluoro Ethyl 1,1,2-trifluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 1,1,2-trifluoroethyl ether, hexafluoroethyl 1,1,2-tri Fluoroethyl ether, 1,1-difluoroethyl 1,2,2-trifluoroethyl ether, 1,2-difluoroethyl 1,2,2-trifluoroethyl ether, 2,2-di Fluoroethyl 1,2,2-trifluoroethyl ether, 1,1,1-trifluoroethyl 1,2,2-trifluoroethyl ether, 1,1,2-trifluoroethyl 1,2 ,2-trifluoroethyl ether, di(1,2,2-trifluoroethyl) ether, 2,2,2-trifluoroethyl 1,2,2-trifluoroethyl ether, 1,1, 1,2-tetrafluoroethyl 1,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl 1,2,2-trifluoroethyl ether, 1,2,2, 2-tetrafluoroethyl 1,2,2-trifluoroethyl ether, pentafluoroethyl 1,2,2-trifluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 1, 2,2-trifluoroethyl ether, hexafluoroethyl 1,2,2-trifluoroethyl ether, 1,1-difluoroethyl 2,2,2-trifluoroethyl ether, 1,2- Difluoroethyl 2,2,2-trifluoroethyl ether, 2,2-difluoroethyl 2,2,2-trifluoroethyl ether, 1,1,1-trifluoroethyl 2,2, 2-trifluoroethyl ether, 1,1,2-trifluoroethyl 2,2,2-trifluoroethyl ether, 1,2,2-trifluoroethyl 2,2,2-trifluoroethyl Ether, di(2,2,2-trifluoroethyl) ether, 1,1,1,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether, 1,1,2,2-tetra Fluoroethyl 2,2,2-trifluoroethyl ether, 1,2,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether, pentafluoroethyl 2,2,2-tri Fluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 2,2,2-trifluoroethyl ether, hexafluoroethyl 2,2,2-trifluoroethyl ether, 1,1 -Difluoroethyl 1,1,1,2-tetrafluoroethyl ether, 1,2-difluoroethyl 1,1,1,2-tetrafluoroethyl ether, 2,2-difluoroethyl 1 ,1,1,2-tetrafluoroethyl ether, 1,1,1-trifluoroethyl 1,1,1,2-tetrafluoroethyl ether, 1,1,2-trifluoroethyl 1,1 ,1,2-tetrafluoroethyl ether, 1,2,2-trifluoroethyl 1,1,1,2-tetrafluoroethyl ether, 2,2,2-trifluoroethyl 1,1,1 ,2-tetrafluoroethyl ether, di(1,1,1,2-tetrafluoroethyl) ether, 1,1,2,2-tetrafluoroethyl 1,1,1,2-tetrafluoroethyl Ether, 1,2,2,2-tetrafluoroethyl 1,1,1,2-tetrafluoroethyl ether, pentafluoroethyl 1,1,1,2-tetrafluoroethyl ether, 1,1, 2,2,2-pentafluoroethyl 1,1,1,2-tetrafluoroethyl ether, hexafluoroethyl 1,1,1,2-tetrafluoroethyl ether, 1,1-difluoroethyl 1,1,2,2-tetrafluoroethyl ether, 1,2-difluoroethyl 1,1,2,2-tetrafluoroethyl ether, 2,2-difluoroethyl 1,1,2, 2-tetrafluoroethyl ether, 1,1,1-trifluoroethyl 1,1,2,2-tetrafluoroethyl ether, 1,1,2-trifluoroethyl 1,1,2,2- Tetrafluoroethyl ether, 1,2,2-trifluoroethyl 1,1,2,2-tetrafluoroethyl ether, 2,2,2-trifluoroethyl 1,1,2,2-tetrafluoro Roethyl ether, 1,1,1,2-tetrafluoroethyl 1,1,2,2-tetrafluoroethyl ether, di(1,1,2,2-tetrafluoroethyl) ether, 1,2 ,2,2-tetrafluoroethyl 1,1,2,2-tetrafluoroethyl ether, pentafluoroethyl 1,1,2,2-tetrafluoroethyl ether, 1,1,2,2,2 -pentafluoroethyl 1,1,2,2-tetrafluoroethyl ether, hexafluoroethyl 1,1,2,2-tetrafluoroethyl ether, 1,1-difluoroethyl 1,2,2 ,2-tetrafluoroethyl ether, 1,2-difluoroethyl 1,2,2,2-tetrafluoroethyl ether, 2,2-difluoroethyl 1,2,2,2-tetrafluoro Ethyl ether, 1,1,1-trifluoroethyl 1,2,2,2-tetrafluoroethyl ether, 1,1,2-trifluoroethyl 1,2,2,2-tetrafluoroethyl ether , 1,2,2-trifluoroethyl 1,2,2,2-tetrafluoroethyl ether, 2,2,2-trifluoroethyl 1,2,2,2-tetrafluoroethyl ether, 1 ,1,1,2-tetrafluoroethyl 1,2,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl 1,2,2,2-tetrafluoroethyl ether , di(1,2,2,2-tetrafluoroethyl) ether, pentafluoroethyl 1,2,2,2-tetrafluoroethyl ether, 1,1,2,2,2-pentafluoroethyl 1,2,2,2-tetrafluoroethyl ether, hexafluoroethyl 1,2,2,2-tetrafluoroethyl ether, 1,1-difluoroethyl pentafluoroethyl ether, 1,2- Difluoroethyl pentafluoroethyl ether, 2,2-difluoroethyl pentafluoroethyl ether, 1,1,1-trifluoroethyl pentafluoroethyl ether, 1,1,2-trifluoroethyl Pentafluoroethyl ether, 1,2,2-trifluoroethyl pentafluoroethyl ether, 2,2,2-trifluoroethyl pentafluoroethyl ether, 1,1,1,2-tetrafluoroethyl Pentafluoroethyl ether, 1,1,2,2-tetrafluoroethyl pentafluoroethyl ether, 1,2,2,2-tetrafluoroethyl pentafluoroethyl ether, di(pentafluoroethyl) ether , 1,1,2,2,2-pentafluoroethyl pentafluoroethyl ether, hexafluoroethyl pentafluoroethyl ether, 1,1-difluoroethyl 1,1,2,2,2-penta Fluoroethyl ether, 1,2-difluoroethyl 1,1,2,2,2-pentafluoroethyl ether, 2,2-difluoroethyl 1,1,2,2,2-pentafluoro Ethyl ether, 1,1,1-trifluoroethyl 1,1,2,2,2-pentafluoroethyl ether, 1,1,2-trifluoroethyl 1,1,2,2,2-penta Fluoroethyl ether, 1,2,2-trifluoroethyl 1,1,2,2,2-pentafluoroethyl ether, 2,2,2-trifluoroethyl 1,1,2,2,2 -Pentafluoroethyl ether, 1,1,1,2-tetrafluoroethyl 1,1,2,2,2-pentafluoroethyl ether, 1,1,2,2-tetrafluoroethyl 1,1 ,2,2,2-pentafluoroethyl ether, 1,2,2,2-tetrafluoroethyl 1,1,2,2,2-pentafluoroethyl ether, pentafluoroethyl 1,1,2 Fluorination of 2,2-pentafluoroethyl ether, di(1,1,2,2,2-pentafluoroethyl) ether, hexafluoroethyl pentafluoroethyl ether, dihexafluoroethyl ether, etc. the group consisting of ethers; And bis (fluoromethyl) sulfate, bis (2-fluoroethyl) sulfate, bis (3-fluoropropyl) sulfate, bis (difluoromethyl) sulfate, bis (2,2-difluoroethyl) sulfate , Bis (3,3-difluoropropyl) sulfate, bis (trifluoromethyl) sulfate, bis (2,2,2-trifluoroethyl) sulfate, bis (3,3,3-trifluoropropyl ) sulfate, methyl (fluoromethyl) sulfate, methyl (2-fluoroethyl) sulfate, methyl (3-fluoropropyl) sulfate, methyl (difluoromethyl) sulfate, methyl (2,2-difluoroethyl ) sulfate, methyl (3,3-difluoropropyl) sulfate, methyl (trifluoromethyl) sulfate, methyl (2,2,2-trifluoroethyl) sulfate, methyl (3,3,3-trifluoro Ropropyl) sulfate, ethyl (fluoromethyl) sulfate, ethyl (2-fluoroethyl) sulfate, ethyl (3-fluoropropyl) sulfate, ethyl (difluoromethyl) sulfate, ethyl (2,2-difluoro Roethyl) sulfate, ethyl (3,3-difluoropropyl) sulfate, ethyl (trifluoromethyl) sulfate, ethyl (2,2,2-trifluoroethyl) sulfate, ethyl (3,3,3- Trifluoropropyl) sulfate, propyl (fluoromethyl) sulfate, propyl (2-fluoroethyl) sulfate, propyl (3-fluoropropyl) sulfate, propyl (difluoromethyl) sulfate, propyl (2,2- Difluoroethyl) sulfate, propyl (3,3-difluoropropyl) sulfate, propyl (trifluoromethyl) sulfate, propyl (2,2,2-trifluoroethyl) sulfate, propyl (3,3, 3-trifluoropropyl) sulfate, (fluoromethyl) (2-fluoroethyl) sulfate, (fluoromethyl) (3-fluoropropyl) sulfate, (fluoromethyl) (difluoromethyl) sulfate, (fluoromethyl) (2,2-difluoroethyl) sulfate, (fluoromethyl) (3,3-difluoropropyl) sulfate, (fluoromethyl) (trifluoromethyl) sulfate, (fluoro Methyl) (2,2,2-trifluoroethyl) sulfate, (fluoromethyl) (3,3,3-trifluoropropyl) sulfate, (2-fluoroethyl) (3-fluoropropyl) sulfate , (2-fluoroethyl) (difluoromethyl) sulfate, (2-fluoroethyl) (2,2-difluoroethyl) sulfate, (2-fluoroethyl) (3,3-difluoro Propyl) sulfate, (2-fluoroethyl) (trifluoromethyl) sulfate, (2-fluoroethyl) (2,2,2-trifluoroethyl) sulfate, (2-fluoroethyl) (3, 3,3-trifluoropropyl) sulfate, (3-fluoropropyl) (difluoromethyl) sulfate, (3-fluoropropyl) (2,2-difluoroethyl) sulfate, (3-fluoro Propyl) (3,3-difluoropropyl) sulfate, (3-fluoropropyl) (trifluoromethyl) sulfate, (3-fluoropropyl) (2,2,2-trifluoroethyl) sulfate, (3-fluoropropyl)(3,3,3-trifluoropropyl)sulfate, (difluoromethyl)(2,2-difluoroethyl)sulfate, (difluoromethyl)(3,3- Difluoropropyl) sulfate, (difluoromethyl) (trifluoromethyl) sulfate, (difluoromethyl) (2,2,2-trifluoroethyl) sulfate, (difluoromethyl) (3, 3,3-trifluoropropyl) sulfate, (2,2-difluoroethyl) (3,3-difluoropropyl) sulfate, (2,2-difluoroethyl) (trifluoromethyl) sulfate , (2,2-difluoroethyl) (2,2,2-trifluoroethyl) sulfate, (2,2-difluoroethyl) (3,3,3-trifluoropropyl) sulfate, ( 3,3-difluoropropyl)trifluoromethyl)sulfate, (3,3-difluoropropyl)(2,2,2-trifluoroethyl)sulfate and (3,3-difluoropropyl) a group consisting of sulfates such as (3,3,3-trifluoropropyl) sulfate; It may be any one or more selected from the organic solvent group consisting of, etc., but this is only one example and can be used without particular limitation as long as it is commonly used in the art, and is not necessarily limited thereto. Preferably, the organic solvent may be a mixture of two or more selected from the aforementioned cyclic carbonates, fluorinated cyclic carbonates, linear carbonates, fluorinated linear carbonates, linear esters, and fluorinated esters. there is.

In this case, the electrolyte solution for a lithium secondary battery may contain 0.01 to 5 parts by weight of a compound satisfying Formula 1 based on 100 parts by weight of a mixture of the lithium salt and the organic solvent, preferably 0.1 to 3 parts by weight, More preferably, it may contain 0.2 to 1 part by weight.

The concentration of the electrolyte for a lithium secondary battery may be adjusted to a level commonly used in the art, and specifically, for example, the concentration of the lithium salt in the electrolyte solution is 0.1 to 20M, preferably 0.2 to 10M, more preferably 0.5M. to 1.5M.

The electrolyte solution for a lithium secondary battery may further include an additive.

The additive may be an additive that directly forms or assists in the formation of SEI (Solid-Electrolyte Interphase) of the cathode and anode; Additives that increase the ionic conductivity of SEI; additives that remove active substances such as HF and PF ₅ ; additives to prevent overfilling; Additives to increase flame retardancy; additives that promote uniform reduced deposition of lithium; Additives that help solvation of ions; Or an additive that prevents corrosion of the current collector; it may be.

Additives assisting the formation of the SEI of the positive electrode include, for example, trimethyl boroxine (TMB), triethyl boroxine, trimethyl borate, triethyl borate (TEB) and a group consisting of boron-based groups such as tris(trimethylsilyl) borate (TMSB); 4,4-bi(1,3,2-dioxathiolane)2,2-dioxide (BDTD), 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane-2-oxide (TFEOP), etc. The group consisting of sulfur series of; and methyl 2,2,2-trifluoroethyl carbonate (FEMC), methyl difluoroacetate (DFMAc) and ethyl difluoroacetate (DFEAc) a group consisting of a fluorinated series in which fluoroethylene carbonate (FEC) is added in combination with fluoroethylene carbonate; a group consisting of phosphate and fluorinated phosphate compounds; a group consisting of phosphonate compounds; It may be any one or more selected from the like, but any additive that assists in the formation of SEI of a previously known positive electrode may be used, and is not necessarily limited to the above examples.

Additives that directly form or assist in the formation of the SEI of the negative electrode include, for example, fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinylethylene carbonate (VEC), allyl Ethyl carbonate, vinyl acetate, divinyl adipate, acrylic acid nitrile, 2-vinyl pyridine, γ-butyrolactone ( γ-butyrolactone (GBL), methyl phenyl carbonate, succinic imide, maleic acid anhydride, succinic acid anhydride, methyl chloroformate ( a group consisting of cyclic compounds such as methyl chloroformate), methyl cinnamate, and furan derivatives having double bonds; a group consisting of phosphate and fluorinated phosphate compounds; a group consisting of phosphonate compounds; a group consisting of vinyl-containing silane compounds; and a group consisting of nitrate and nitrite compounds; It may be any one or more selected from the like, but it is possible to use any additive that directly forms or assists in the formation of a known SEI, and is not necessarily limited to the above examples.

Additives that increase the ionic conductivity of the SEI include, for example, LiPO ₃ F ₂ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ . LiN(FSO ₂ ) ₂ , LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ) (x, y are 0 or natural numbers), LiB(C ₂ O ₄ ) ₂ , LiF ₂ B(C ₂ O ₄ ), LiF ₂ B(FC ₃ O ₄ ), LiPF ₄ (C ₂ O ₄ ), LiPF ₂ (C ₂ O ₄ ) ₂ , LiP(C ₂ O ₄ ) ₃ , sulfone )-based, sultone-based, sulphite-based and sulfate-based, and the like, or a mixture of two or more selected from the group consisting of, but is not necessarily limited thereto.

The additive that removes the active material is, for example, a group having an isocyanate (N=C=O) functional group such as p-toluene sulfonyl isocyanate (PTSI); pyrrolidinone groups such as 1-methyl-2-pyrrolidinone; a group consisting of silane derivatives having a Si-O structure, such as dimethoxy dimethyl silane (DODSi) and diphenyl dimethoxy silane (DPDMS); a group consisting of phosphoramides such as hexamethyl phosphoramide; Tris (2,2,2-trifluoroethyl) phosphite (tris (2-2-2-trifluoroethyl) phosphite), tris (trimethoxy silyl) phosphite (tris (trimethyl silyl) phosphite, TMSPi), etc. a group consisting of phosphite; And a group consisting of phosphonites such as diethyl phenyl phosphonite (DEPP); may be any one or more selected from the group consisting of, but if it is an additive that removes a known active substance, it can be used It is possible, and is not necessarily limited to the above example.

Additives that prevent overcharging include metallocenes, tetracyano ethylene, tetramethyl phenylene diamine, dihydrophenazine, and bipyridyl carbonates. a group consisting of organic compounds such as biphenyl carbonates, 2,7-diacetyl thianthrene and phenothiazine; and a group consisting of lithium salts such as Li ₂ B ₁₂ F _x H _12-x (lithium fluorododecaborates) and lithium bis(oxalato)borate (LiBOB); It may be any one or more selected from the like, but any known additive that prevents overcharging can be used, and is not necessarily limited to the above examples.

Additives that increase the flame retardancy include, for example, a group consisting of alkyl phosphates such as trimethyl phosphate and triethyl phosphate; a group consisting of fluorinated phosphates such as tris(2,2,2-trifluoroethyl)phosphate; a group consisting of phosphazenes such as hexamethoxy cyclo phosphazene; a group consisting of fluorinated ethers and fluorinated carbonates such as methyl nonafluorobutyl ether (MFE), fluoroethylene carbonate, and fluoropropylene carbonate; It may be any one or more selected from the like, but it is possible to use any additive that enhances known flame retardancy, and is not necessarily limited to the above examples.

Additives that promote uniform reduction deposition of lithium include, for example, lithium nitride (LiNO ₃ ), tetrahydrofuran, 2-methyltetrahydrofuran, thiophene, 2 -Methylthiophene, nitromethane, tetraalkylammonium chloride, cetyl trimethyl ammonium chloride, lithium perfluorooctane sulfonate, It may be any one or more selected from tetraethylammonium perfluorooctane sulfonate, perfluoropolyethers, AlI ₃ and SnI ₂ , etc., which promotes uniform reduction deposition of lithium known in the art. Any additive can be used, and is not necessarily limited to the above examples.

Additives that help the solvation of the ion include, for example, 12-crown-4 and its derivatives, tris (pentafluorophenyl) borane, and cyclic aza-ether compounds. And it may be any one or more selected from borole compounds, etc., but any additive that helps the solvation of known ions can be used, and is not necessarily limited to the above examples.

The additive for preventing corrosion of the current collector includes, for example, a lithium salt compound having a chemical formula of LiPF ₆ , LiBF ₄ , LiN(SO ₂ C _n F _2n+1 ) ₂ (n=2 to 4), and the like it could be

The content of the additive may be adjusted in the range of 0.01 to 10% by weight based on the weight of the electrolyte solution for a lithium secondary battery according to desired physical properties.

A self-extinguishing time (SET) of the electrolyte for a lithium secondary battery may be less than 20 s·g ^-1 .

In addition, the present invention provides a lithium secondary battery including the electrolyte solution for the lithium secondary battery.

The lithium secondary battery may include an electrolyte for a lithium secondary battery; anode; cathode; And a separator; may be one containing. At this time, the lithium secondary battery is an all-solid or all-solid electrolyte capable of all-solidifying electrolytes such as polymers for gel polymer electrolytes, polymer matrices, similar solid materials, semi-solid materials, solid polymer electrolytes, oxide and sulfide inorganic solid electrolytes, in addition to electrolytes for lithium secondary batteries. It may further include a solid-state battery material.

The polymer electrolyte matrix is to improve the mechanical properties or high-temperature stability of the battery, specifically polyacrylate, polymethacrylate, polyvinylidene fluoride (PVDF), polyhexafluoro Polyhexafluoro propylene (PHFP), polyethylene oxide (PEO), polypropylene oxide (PPO), polydimethyl siloxane, polyacrylonitrile (PAN) and polyvinyl It may be any one or a mixture of two or more selected from the group consisting of polymers such as chloride (polyvinyl chloride, PVC) and PEGDME, and copolymers mixed with them, and is not limited as long as it is a known polymer material for a lithium secondary battery.

The polymer matrix may include crosslinking monomers for crosslinking each other. The crosslinking monomer has a plurality of functional groups in the monomer, and examples thereof include substances such as glutaraldehyde, tris allylamine, and tetraallyloxyethane.

The lithium secondary battery may use an all-solid electrolyte obtained by converting the lithium secondary battery electrolyte into a solid state.

The cathode may include a cathode active material; bookbinder; conductive material; And a current collector; may include.

The cathode active material is LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _1-x Co _x O ₂ , LiNi _x Co _y Mn _z O ₂ (x+y+z=1), LiNi _x Co _y Al _z O ₂ (x+y+z=1), LiNi _x Mn _y M _z O ₂ (x+y+z=1, M is a divalent or trivalent or transition metal), LiFePO ₄ , LiMnPO _4, LiCoPO _4, LiFe _1-x M _x PO ₄ (M is a transition metal), a(Li ₂ MnO ₃ ) b(LiNI _x Co _y Mn _z O ₂ ) (a+b=1, x+y+z=1 ), Li _1.2 Ni _0.13 Co _0.13-x Mn _0.54 Al _x O _2(1-y) F _2y (x, y are mutually independent real numbers ranging from 0 to 0.05), Li _1.2 Mn _(0.8-a) M _a O ₂ (M is a divalent or trivalent metal or transition metal), Li ₂ N _1-x M _x O ₃ (N is a divalent, trivalent or tetravalent metal or transition metal, M is a divalent or trivalent metal or transition metal metal), Li _1+x N _yz M _z O ₂ (N is Ti or Nb, M is any one selected from V, Ti, Mo or W), Li ₄ Mn _2-x M _x O ₅ (M is a metal or transition metal), Li _x M _2-x O ₂ (M is a metal or transition metal such as Ti, Zr, Nb, Mn), Li ₂ O/Li ₂ Ru _1-x M _x O ₃ (M is a metal or transition metal) ), etc., but this is only one example, and any known positive electrode active material can be used, and is not necessarily limited to the above example.

The conductive material is used to impart conductivity to the electrode, and any material having electronic conductivity without causing chemical change may be used without particular limitation. As specific examples, graphite, carbon black, super blood, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, carbon nanotube, carbon nanowire, graphene, graphitized mesocarbon microbeads , carbon-based materials such as fullerene and amorphous carbon; powdery or fibrous transition metals such as copper, nickel, aluminum, and silver; conductive whiskers such as potassium titanate; conductive metal oxides such as zinc oxide and titanium oxide; Or polyphenylene derivatives, PEDOT (poly (3,4-ethylenedioxythiophene)) and PSS (polystyrene sulfonate), such as conductive polymers and copolymers thereof; may include, but this is only an example, a known challenge Ash can be used, and is not necessarily limited to the above examples.

The binder is used to impart adhesion between the positive electrode active material and the conductive material particles or between the positive electrode active material and the current collector, and any adhesive material that is chemically resistant and does not cause chemical change can be used without particular limitation. Specific examples include polyvinylidene fluoride (PVDF), polyimide (PI), fluoro polyimide (FPI), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), tetrafluoro Rothylene (PTFE), Polyethylene (PE), Polypropylene (PP), Polyurethane, Polyurea, Ethylene-Propylene-Diene Polymer (EPDM), Sulphonated EPDM, Styrene-Butadiene Rubber (SBR), Fluoroelastomer, Carboxy It may include methyl cellulose (CMC), hydroxypropyl cellulose, regenerated cellulose and starch or copolymers thereof, etc., but this is only an example, and any known binder can be used, and is not necessarily limited to the above examples. don't

The current collector serves as a passage for transferring electrons from an external power source to an active material or between a cathode active material and an anode active material, and may use a transition metal thin film, and in particular, aluminum is used as a current collector for the anode. can

The negative electrode may include an anode active material; bookbinder; conductive material; And a current collector; may include.

The anode active material is a medium for storing lithium ions by reducing them to lithium, and includes carbon-based materials such as natural graphite, artificial graphite (MCMB, etc.), hard carbon and soft carbon, graphene, carbon nanotubes, and fullerene; silicon-based materials such as silicon, silicon carbon composites, silicon oxides (SiO, SiO _x ), silicon oxide carbon composites, silica and silicates; and lithium metal, Li ₄ Ti ₅ O ₁₂ , metal oxide (metal = Ti, V, Cr, Mn, Fe, Co, Ni, Nb, Mo, W, etc.); It may be any one selected from the group consisting of, etc., but this is only an example, and any known anode active material can be used, and is not necessarily limited to the above example.

Since the binder and the conductive material used for the negative electrode are the same as those of the positive electrode described above, overlapping descriptions will be omitted.

The current collector has the same purpose and configuration as the case of the anode described above, but in particular, copper may be used as a current collector for the anode.

The separation membrane may be used without particular limitation commonly used in the art. Specifically, for example, porous polyolefin thin films such as polyethylene and polypropylene; non-woven fabrics made of polymer fibers such as polyacrylate and polyacrylonitrile; and porous polyolefin thin films coated with ceramics.

Hereinafter, an electrolyte solution for a lithium secondary battery according to the present invention and a lithium secondary battery including the same will be described in more detail through examples. However, the following examples are only one reference for explaining the present invention in detail, but the present invention is not limited thereto, and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is merely to effectively describe specific embodiments and is not intended to limit the present invention. In addition, the unit of additives not specifically described in the specification may be % by weight.

[Example 1]

1M LiPF ₆ in PC(propylene carbonate):DFDEC(di-(2,2,2 trifluoroethyl)carbonate) (volume ratio 3:7) 1 part by weight of FEC (fluoroethylene carbonate) and 0.25 parts by weight of 100 parts by weight of electrolyte An electrolyte solution for a lithium secondary battery was prepared by adding parts by weight of pentafluoropropionic anhydride (PFA).

[Example 2]

An electrolyte solution for a lithium secondary battery was prepared by adding 1 part by weight of FEC and 0.25 part by weight of PFA to 100 parts by weight of 1M LiPF ₆ in EC (ethylene carbonate):EMC (ethylmethyl carbonate) (volume ratio 3:7) electrolyte.

[Example 3]

An electrolyte solution for a lithium secondary battery was prepared by adding 1 part by weight of PFA to 100 parts by weight of 1M LiPF ₆ in EC:EMC (volume ratio 3:7) electrolyte.

[Example 4]

An electrolyte solution for a lithium secondary battery was prepared by adding 1 part by weight of FEC and 1 part by weight of PFA to 100 parts by weight of 1M LiPF ₆ in PC:TFEA (2,2,2-trifluoroethyl acetate) (volume ratio 3:7) electrolyte.

[Comparative Example 1]

An electrolyte solution for a lithium secondary battery was prepared by adding only 1 part by weight of FEC to 100 parts by weight of 1M LiPF ₆ in PC:DFDEC (volume ratio 3:7) electrolyte.

[Comparative Example 2]

A 1M LiPF ₆ in EC:EMC (volume ratio of 3:7) electrolyte was prepared as an electrolyte for a lithium secondary battery without additives.

[Comparative Example 3]

An electrolyte solution for a lithium secondary battery was prepared by adding only 1 part by weight of FEC to 100 parts by weight of 1M LiPF ₆ in EC:EMC (volume ratio 3:7) electrolyte.

[Comparative Example 4]

An electrolyte solution for a lithium secondary battery was prepared by adding only 2 parts by weight of FEC to 100 parts by weight of 1M LiPF ₆ in EC:EMC (volume ratio 3:7) electrolyte.

[Comparative Example 5]

An electrolyte solution for a lithium secondary battery was prepared by adding only 1 part by weight of FEC to 100 parts by weight of 1M LiPF ₆ in PC:TFEA (volume ratio 3:7) electrolyte.

A lithium secondary battery using Examples 1 to 4 and Comparative Examples 1 to 5 as an electrolyte was prepared. Specifically, the lithium secondary battery using Examples 1 and 2 and Comparative Examples 1 to 3 as an electrolyte was manufactured as a coin battery using a lithium metal negative electrode, a Li-rich positive electrode, and a PP (polypropylene) separator, and the Example 3 , 4 and Comparative Examples 4 and 5 were used as electrolytes and were manufactured as coin batteries using a graphite anode, LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811), and a PP separator.

During charging and discharging of the battery, the C-rate is calculated as follows.

C-rate=(1/full charge or fully discharge time (hr))

[Characteristic evaluation method]

A. Evaluation of charge and discharge performance (Example 1 and Comparative Example 1)

The electrochemical performance of the lithium secondary battery including Example 1 and Comparative Example 1 was measured by charging and discharging at 18 C (3.3 minutes required for charging). At this time, the charge cutoff voltage was set to a high voltage of 4.8V, the discharge cutoff voltage was set to 2.0V, and the temperature was maintained at a high temperature of 45°C.

The discharge capacity and capacity retention rate compared to 0.2C (requiring 5 hours for charging) shown in Table 1 below are as described below.

The discharge capacity against 0.2C is calculated as follows.

Discharge capacity against 0.2C (%) = (18C discharge capacity / 0.2C discharge capacity) * 100

The capacity retention rate is calculated as follows.

Capacity retention rate (%) = (Capacity at 100th discharge/Capacity at 1st discharge)*100

initial discharge capacity
(mAh/g) Discharge capacity compared to 0.2C (%) Capacity retention rate (%) Initial coulombic efficiency (%) Example 1 146 55 94 81.9 Comparative Example 1 167 60 55 86.9

Referring to Table 1, in the case of using Example 1, despite the harsh conditions of a high voltage of 4.8V, a high rate of 18C, and a high temperature of 45 ° C., the initial capacity decreased, but the capacity retention rate was greatly improved, leading to 100 charge and discharge cycles. Even when the capacity is maintained at 94%, it can be seen that Example 1 has significantly superior electrochemical performance and lifetime characteristics compared to Comparative Example 1.

B. Interfacial resistance evaluation (Example 1 and Comparative Example 1)

Referring to FIG. 1, the interfacial resistance (Z) of Comparative Example 1 (non-combustible electrolyte solution without inventive additives) during the first charge and discharge is 50Ω or less, and is smaller than about 210Ω of Example 1 (non-combustible electrolyte solution containing inventive additives), but 100 During repeated charging and discharging, the resistance of Comparative Example 1 exceeded 400Ω and increased by more than 350Ω, whereas the resistance of Example 1 was less than 270Ω, and the interface resistance increased by only about 60Ω, so the additives included in Example 1 suppressed the change in interface resistance. It can be confirmed that there is an excellent characteristic to do.

C. Evaluation of charge and discharge performance (Example 2 and Comparative Examples 2 and 3)

The electrochemical performance of the lithium secondary battery including Example 2 and Comparative Examples 2 and 3, respectively, was measured by charging and discharging at 20 C (3 minutes required for charging). At this time, the charge and discharge cutoff voltage was set to 2.0 ~ 4.8V, and the temperature was maintained at 45 ℃.

The discharge capacity and capacity retention rate compared to 0.2 C shown in Table 2 below are as described below.

The discharge capacity against 0.2C is calculated as follows.

Discharge capacity against 0.2C (%) = (20C discharge capacity / 0.2C discharge capacity) * 100

The capacity retention rate is calculated as follows.

Capacity retention rate (%) = (capacity at nth discharge/capacity at first discharge)*100

initial discharge capacity
(mAh/g) Discharge capacity compared to 0.2C (%) Capacity retention rate (%) Initial coulombic efficiency (%) Example 2 118 44 76 (400th) 82.9 Comparative Example 2 111 41 0 (360th) 84.5 Comparative Example 3 98 36 12 (400th) 82.7

Referring to Table 2, in the case of using Example 2, despite the harsh conditions of a high voltage of 4.8V, a high rate of 20C and a high temperature of 45 ° C., the initial capacity and capacity retention rate were greatly improved, even during 400 charge and discharge cycles. It can be seen that the capacity is maintained at 76%, and Example 2 has significantly superior electrochemical performance compared to Comparative Examples 2 and 3.

D. Interfacial resistance evaluation (Example 2 and Comparative Example 3)

Referring to FIG. 2, the interfacial resistance of the commercial electrolyte containing the inventive additive is smaller than that of the commercial electrolyte without the inventive additive from the first charge and discharge, and the interfacial resistance of the commercial electrolyte without the inventive additive is greatly increased during the 400th charge and discharge. The commercial electrolyte containing the inventive additive suppressed the increase in interfacial resistance. Through this, it can be confirmed that there is an excellent property of suppressing the change in interfacial resistance of the commercial electrolyte containing the inventive additive.

E. Evaluation of charge and discharge performance (Example 3 and Comparative Example 4)

The electrochemical performance was measured by charging and discharging the lithium secondary battery including each of Example 3 and Comparative Example 4 at 3C (20 minutes required for charging). At this time, the charge and discharge cutoff voltage was set to 2.7 ~ 4.3V, and the temperature was maintained at 45 ℃.

The discharge capacity and capacity retention rate compared to 0.1C (requiring 10 hours for charging) shown in Table 2 below are as described below.

The discharge capacity against 0.1C is calculated as follows.

Discharge capacity against 0.1C (%) = (3C discharge capacity / 0.1C discharge capacity) * 100

The capacity retention rate is calculated as follows.

Capacity retention rate (%) = (capacity at nth discharge/capacity at first discharge)*100

initial discharge capacity
(mAh/g) Discharge capacity compared to 0.1C (%) Capacity retention rate (%) Initial coulombic efficiency (%) Example 3 180 92 95 (200th) 82.3 Comparative Example 4 195 93 24th (100th) 77.6

Referring to Table 3, in the case of using Example 3, it can be seen that the initial discharge capacity is lower than that of Comparative Example 4, but the initial coulombic efficiency is high. In addition, it can be seen that the capacity retention rate is very high at 95% at 200 charge/discharge cycles, and there is a big difference from Comparative Example 4, which decreased to 24% at 100 cycles.

F. Evaluation of charge and discharge performance (Example 4 and Comparative Example 5)

The electrochemical performance was measured by charging and discharging the lithium secondary battery including each of Example 4 and Comparative Example 5 at 3C (20 minutes required for charging). At this time, the charge and discharge cutoff voltage was set to 2.7 ~ 4.3V, and the temperature was maintained at 45 ℃.

The discharge capacity and capacity retention rate compared to 0.1C (requiring 10 hours for charging) shown in Table 2 below are as described below.

The discharge capacity against 0.1C is calculated as follows.

Discharge capacity against 0.1C (%) = (3C discharge capacity / 0.1C discharge capacity) * 100

The capacity retention rate is calculated as follows.

Capacity retention rate (%) = (capacity at nth discharge/capacity at first discharge)*100

initial discharge capacity
(mAh/g) Discharge capacity compared to 0.1C (%) Capacity retention rate (%) Initial coulombic efficiency (%) Example 4 190 96 66 (400th) 81.7 Comparative Example 5 189 98 2 (100th) 77.6

Referring to Table 4, it can be seen that in the case of using Example 4, all values except for the discharge capacity at 0.1C exceed those of Comparative Example 5. In particular, 400 charging and discharging of Example 4 was possible, and the capacity was maintained at 66%, whereas Comparative Example 5 was almost impossible to use because the capacity was reduced to 2% compared to the first cycle in the 100th charging and discharging cycle.

E. Measurement of self-extinguishing time (SET, sec/g) (Examples 1 and 4 and Comparative Examples 1 and 5)

To measure the nonflammability and flame retardancy of the electrolyte, each electrolyte was ignited with a torch, and after removing the torch, the self-extinguishing time (s) per weight (g) of the electrolyte was measured. It can be defined as nonflammable when SET < 6, flame retardant when 6 ≤ SET < 20, and flammable when 20 ≤ SET.

SET (s/g) Flammability evaluation Example 1 0 nonflammable Example 4 0 nonflammable Comparative Example 1 0 nonflammable Comparative Example 5 0 nonflammable

As shown in Table 4, Examples 1 and 4 and Comparative Examples 1 and 5 do not ignite the electrolyte itself, and it can be confirmed that they are nonflammable.

Although the present invention has been described through specific details and limited examples as described above, these are only provided to help the overall understanding of the present invention, and the present invention is not limited to the above examples, and the field to which the present invention belongs Those skilled in the art can make various modifications and variations from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and it will be said that not only the claims to be described later, but also all modifications equivalent or equivalent to these claims belong to the scope of the present invention. .

Claims (7)

In the electrolyte solution for a lithium secondary battery containing a lithium salt and an organic solvent, the electrolyte solution for a lithium secondary battery comprising a compound satisfying the following formula (1).
[Formula 1]

(In Formula 1 above,
R ₁ and R ₂ are each independently C1 to C4 alkyl or C1 to C4 fluorinated alkyl, but at least one of R ₁ and R ₂ includes fluorine.) According to claim 1,
The organic solvent is an electrolyte solution for a lithium secondary battery comprising a compound satisfying Formula 2 below.
[Formula 2]

(In Formula 2 above,
R ₁ and R ₂ are independently of each other CH ₃ or CH _x F _3-x (x is an integer from 0 to 3),
m and n are integers from 1 to 3 that are independent of each other.) According to claim 1,
The organic solvent is an electrolyte solution for a lithium secondary battery comprising a compound satisfying Formula 3 below.
[Formula 3]

(In Formula 3,
R ₁ and R ₂ are independently of each other CH ₃ or CH _x F _3-x (x is an integer from 0 to 3),
m and n are integers from 1 to 3 that are independent of each other.) According to claim 1,
The organic solvent is an electrolyte solution for a lithium secondary battery comprising a compound satisfying Formula 4 below.
[Formula 4]

(In Chemical Formula 4,
X ₁ and X ₂ are each independently H, F, CH ₃ or CH _x F _3-x (x is an integer from 0 to 2).) According to claim 1,
In the electrolyte solution for a lithium secondary battery, the electrolyte solution for a lithium secondary battery comprising 0.01 to 5 parts by weight of a compound satisfying Formula 1 based on 100 parts by weight of a mixture of a lithium salt and the organic solvent. According to claim 1,
The concentration of the lithium salt in the electrolyte for a lithium secondary battery is 0.1 to 20M electrolyte for a lithium secondary battery. An electrolyte solution for a lithium secondary battery according to any one of claims 1 to 7; anode; cathode; And a separator; a lithium secondary battery comprising a.

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