KR20190133659A - Additive for electrolyte of lithium battery, organic electrolytic solution comprising the same and Lithium battery using the solution - Google Patents

Abstract

Provided is an organic electrolytic solution comprising a first lithium salt, an organic solvent, and a bicyclic sulfate-based compound represented by chemical formula 1. In chemical formula 1, A_1, A_2, A_3, and A_4 are independently and covalently bonded and are a substituted or unsubstituted C1-C5 alkylene group, a carbonyl group or a sulfinyl group as a substituent. The A_1 and the A_2 are not covalently bonded at the same time. The A_3 and the A_4 are not covalently bonded at the same time. The present invention can improve high temperature and lifetime properties of a lithium battery.

Description

Organic electrolyte and lithium battery employing the above electrolyte {Additive for electrolyte of lithium battery, organic electrolytic solution comprising the same and Lithium battery using the solution}

The present invention relates to an organic electrolyte and a lithium battery employing the electrolyte.

Lithium batteries are used as power sources for portable electronic devices such as video cameras, mobile phones, and notebook computers. Rechargeable lithium secondary batteries are more than three times higher in energy density per unit weight and can be charged faster than conventional lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries and nickel zinc batteries.

Since lithium batteries operate at high driving voltages, aqueous electrolytes highly reactive with lithium cannot be used. In general, an organic electrolyte is used for a lithium battery. The organic electrolyte is prepared by dissolving lithium salt in an organic solvent. The organic solvent is preferably stable at high voltage, has high ion conductivity, high dielectric constant, and low viscosity.

When an organic electrolyte containing a carbonate-based polar non-aqueous solvent is used in a lithium battery, an irreversible reaction in which an excessive charge is used by a side reaction between an anode / anode and an organic electrolyte during initial charging is performed.

An irreversible reaction forms a passivation layer such as a solid electrolyte interface layer (SEI layer) on the surface of the cathode. In addition, a protection layer is formed on the surface of the anode by the irreversible reaction.

SEI layers and / or protective layers formed using conventional organic electrolytes were easily degraded at high temperatures. In other words, the SEI layer and / or the protective layer were deteriorated in stability at high temperatures.

Therefore, there is a need for an organic electrolyte that can form an SEI layer and / or a protective layer having improved high temperature stability.

One aspect is to provide an organic electrolyte solution containing a novel additive for lithium battery electrolyte.

Another aspect is to provide a lithium battery comprising the organic electrolyte.

According to one aspect,

First lithium salt; Organic solvents; And an organic electrolyte comprising a bicyclic sulfate-based compound represented by Formula 1 below:

<Formula 1>

Where

A ₁ , A ₂ , A ₃ and A ₄ are covalently bonded to each other independently; An alkylene group having 1 to 5 carbon atoms unsubstituted or substituted with a substituent; Carbonyl group; Or a sulfinyl group, provided that A ₁ and A ₂ are not covalent bonds at the same time, and A ₃ and A ₄ are not covalent bonds at the same time.

According to the other side,

anode; cathode; And

A lithium battery comprising the organic electrolyte according to the above is provided.

According to an aspect, by using an organic electrolyte solution including a bicyclic sulfate-based additive having a new structure, high temperature and life characteristics of a lithium battery may be improved.

1 is a graph showing the room temperature discharge capacity of the lithium battery prepared in Examples 4 to 5 and Comparative Example 2.
Figure 2 is a graph showing the room temperature capacity retention rate of the lithium battery prepared in Examples 4 to 5 and Comparative Example 2.
3 is a graph showing the high-temperature discharge capacity of the lithium batteries prepared in Examples 4 to 5 and Comparative Example 2.
Figure 4 is a graph showing the high temperature capacity retention rate of the lithium batteries prepared in Examples 4 to 5 and Comparative Example 2.
Figure 5 is a graph showing the room temperature capacity retention rate of the lithium battery prepared in Example 4 and Comparative Example 2.
6 is a graph showing the high temperature capacity retention rate of the lithium batteries prepared in Example 4 and Comparative Example 2. FIG.
7 is a schematic view of a lithium battery according to an exemplary embodiment.
<Explanation of symbols for the main parts of the drawings>
1: lithium battery 2: negative electrode
3: anode 4: separator
5: battery case 6: cap assembly

Hereinafter, an organic electrolyte and a lithium battery employing the electrolyte according to exemplary embodiments will be described in more detail.

According to an embodiment, the organic electrolyte may include a first lithium salt; Organic solvents; And bicyclic sulfate-based compounds represented by Formula 1 below:

<Formula 1>

Wherein A ₁ , A ₂ , A ₃ and A ₄ are independently of each other covalent bonds; An alkylene group having 1 to 5 carbon atoms unsubstituted or substituted with a substituent; Carbonyl group; Or a sulfinyl group, provided that A ₁ and A ₂ are not covalent bonds at the same time, and A ₃ and A ₄ are not covalent bonds at the same time.

An organic electrolyte solution for a lithium battery containing a bicyclic sulfate-based compound as an additive can improve battery performance such as high temperature characteristics and lifetime characteristics of a lithium battery.

The bicyclic sulfate-based compound may have a structure in which two sulfate rings are connected in a spiro form.

The reason why the bicyclic sulfate-based compound is added to the electrolytic solution to improve the performance of the lithium battery will be described in more detail below. This is to help the understanding of the present invention, and the scope of the present invention is limited to the scope of the following description. no.

The sulfate ester group included in the bicyclic sulfate-based compound may affect the properties of the SEI film formed on the surface of the cathode by accepting electrons from the surface of the cathode during charging and reacting with itself or reacting with the already reduced polar solvent molecules. . For example, the bicyclic sulfate-based compound including the sulfate ester group can more easily receive electrons from the negative electrode than the polar solvent. That is, the bicyclic sulfate-based compound may be reduced at a voltage lower than that of the polar solvent and reduced before the polar solvent is reduced.

For example, the bicyclic sulfate-based compound may be more easily reduced and / or decomposed into radicals and / or ions upon charge by including sulfate ester groups. Thus, radicals and / or ions can be combined with lithium ions to form a suitable SEI layer on the negative electrode to inhibit further decomposition product formation of the solvent. The bicyclic sulfate-based compound may form a covalent bond with, or be adsorbed to, the electrode surface, for example, with various functional groups or carbon-based cathodes present on the surface of the carbon-based negative electrode. By such bonding and / or adsorption, a modified SEI layer having improved stability that maintains a solid state even after prolonged charging and discharging may be formed as compared with an SEI layer formed only by an organic solvent. In addition, such a rigid modified SEI layer can more effectively block the entry of the organic solvent solvated by the lithium ion into the electrode during the intercalation of the lithium ion. Therefore, since the modified SEI layer more effectively blocks direct contact between the organic solvent and the negative electrode, reversibility of lithium ion occlusion / release can be further improved, and as a result, the discharge capacity of the battery can be increased and the life characteristics can be improved.

In addition, since the bicyclic sulfate-based compound may be coordinated on the surface of the anode by including a sulfate ester group, it may affect the properties of the protective layer formed on the surface of the anode. For example, the sulfate ester group may be coordinated with transition metal ions of the positive electrode active material to form a complex. By using such a composite, a modified protective layer having improved stability that maintains a solid state even after prolonged charging and discharging may be formed as compared with a protective layer formed only by an organic solvent. In addition, such a rigid modified protective layer can more effectively block the entry of the organic solvent solvated by the lithium ion into the electrode during the intercalation of the lithium ion. Therefore, since the modified protective layer more effectively blocks direct contact between the organic solvent and the positive electrode, reversibility of lithium ion occlusion / release can be further improved, and as a result, battery stability can be increased and life characteristics can be improved.

In addition, the bicyclic sulfate-based compound may be thermally stable because a plurality of rings are bonded in a spiro form compared to a general sulfate-based compound and have a relatively large molecular weight.

As a result, the bicyclic sulfate-based compound may form an SEI layer on the surface of the cathode or a protective layer on the surface of the anode, and may improve lifespan characteristics of the lithium battery at high temperatures by having improved thermal stability.

One or more of A ₁ , A ₂ , A ₃ and A ₄ in the bicyclic sulfate-based compound represented by Formula 1 included in the organic electrolyte includes an unsubstituted alkylene group having 1 to 5 carbon atoms or substituted 1 to 5 carbon atoms. An alkylene group, wherein the substituent of the substituted alkylene group having 1 to 5 carbon atoms is unsubstituted or substituted with halogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms unsubstituted or substituted with halogen, or substituted with halogen Unsubstituted alkynyl group having 2 to 20 carbon atoms, cycloalkenyl group having 3 to 20 carbon atoms unsubstituted or substituted with halogen, heterocyclyl group having 3 to 20 carbon atoms unsubstituted or substituted with halogen, substituted or unsubstituted with halogen Polar action comprising an aryl group having 6 to 40 carbon atoms, a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen, or one or more heteroatoms It may be a flag.

For example, at least one of A ₁ , A ₂ , A _3, and A ₄ is an unsubstituted alkyl group having 1 to 5 carbon atoms or a substituted alkylene group having 1 to 5 carbon atoms, and substituted alkyl having 1 to 5 carbon atoms. The substituent of the ethylene group is halogen, methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, trifluoromethyl group, tetrafluoroethyl group, phenyl group, naphthyl group, tetrafluorophenyl group, pyrrolyl group, or pyri It may be a diyl group, but is not necessarily limited to any of these may be used as long as it can be used as a substituent of an alkylene group in the art.

For example, in the bicyclic sulfate-based compound represented by Formula 1, the substituent of the alkylene group may be a polar functional group including a hetero atom, and the hetero atoms of the polar functional group may be oxygen, nitrogen, phosphorus, sulfur, silicon, and boron. It may be one or more selected from the group consisting of.

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로 이루어진 군에서 선택된 하나 이상을 포함하며,For example, polar functional groups containing heteroatoms include -F, -Cl, -Br, -I, -C (= 0) OR ¹⁶ , -OR ¹⁶ , -OC (= 0) OR ¹⁶ , -R ¹⁵ OC (= O) OR ¹⁶ , -C (= O) R ¹⁶ , -R ¹⁵ C (= O) R ¹⁶ , -OC (= O) R ¹⁶ , -R ¹⁵ OC (= O) R ¹⁶ , -C ( = O) -OC (= O) R ¹⁶ , -R ¹⁵ C (= O) -OC (= O) R ¹⁶ , -SR ¹⁶ , -R ¹⁵ SR ¹⁶ , -SSR ¹⁶ , -R ¹⁵ SSR ¹⁶ ,- S (= O) R ¹⁶ , -R ¹⁵ S (= O) R ¹⁶ , -R ¹⁵ C (= S) R ¹⁶ , -R ¹⁵ C (= S) SR ¹⁶ , -R ¹⁵ SO ₃ R ¹⁶ ,- SO ₃ R ¹⁶ , -NNC (= S) R ¹⁶ , -R ¹⁵ NNC (= S) R ¹⁶ , -R ¹⁵ N = C = S, -NCO, -R ¹⁵ -NCO, -NO ₂ , -R ¹⁵ NO ₂ , -R ¹⁵ SO ₂ R ¹⁶ , -SO ₂ R ¹⁶ ,

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At least one selected from the group consisting of,

R ¹¹ and R ¹⁵ are each independently an alkylene group having 1 to 20 carbon atoms substituted or unsubstituted with halogen; Alkenylene group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; An alkynylene group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; A cycloalkylene group having 3 to 12 carbon atoms unsubstituted or substituted with halogen; An arylene group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Heteroarylene group having 2 to 40 carbon atoms unsubstituted or substituted with halogen; An alkylarylene group having 7 to 15 carbon atoms unsubstituted or substituted with halogen; Or an aralkylene group having 7 to 15 carbon atoms unsubstituted or substituted with halogen,

R ¹² , R ¹³ , R ¹⁴ and R ¹⁶ are each independently hydrogen; halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Alkenyl groups having 2 to 20 carbon atoms unsubstituted or substituted with halogen; An alkynyl group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; A cycloalkyl group having 3 to 12 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; C2-C40 heteroaryl group unsubstituted or substituted with halogen; An alkylaryl group having 7 to 15 carbon atoms unsubstituted or substituted with halogen; Trialkylsilyl group having 7 to 15 carbon atoms unsubstituted or substituted with halogen; Or an aralkyl group having 7 to 15 carbon atoms unsubstituted or substituted with halogen.

For example, a halogen substituted with an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, heteroaryl group, alkylaryl group, trialkylsilyl group, or aralkyl group included in a polar functional group including a hetero atom is fluorine. (F).

For example, the bicyclic sulfate-based compound in the organic electrolyte may be represented by the following formula (2):

<Formula 2> <Formula 3>

In the above formulas, B ₁ , B ₂ , B ₃ , B ₄ , D ₁ , and D ₂ are each independently of the other —C (E ₁ ) (E ₂ ) —; Carbonyl group; Or a sulfinyl group, and E ₁ and E ₂ are each independently hydrogen; halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Alkenyl groups having 2 to 20 carbon atoms unsubstituted or substituted with halogen; An alkynyl group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; A cycloalkenyl group having 3 to 20 carbon atoms unsubstituted or substituted with halogen; A heterocyclyl group having 3 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen.

For example, E ₁ and E ₂ are independently of each other hydrogen; halogen; An alkyl group having 1 to 10 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen.

For example, the E ₁ and E ₂ are independently of each other hydrogen, F, Cl, Br, I, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, trifluoromethyl, tetrafluoro It may be a roethyl group, a phenyl group, a naphthyl group, a tetrafluorophenyl group, a pyrrolyl group, or a pyridinyl group.

For example, E ₁ and E ₂ may be independently of each other hydrogen, fluorine (F), methyl group, ethyl group, trifluoromethyl group, tetrafluoroethyl group or phenyl group.

For example, the bicyclic sulfate-based compound may be represented by the following Chemical Formulas 4 to 5:

<Formula 4> <Formula 5>

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , and R ₂₈ are each independently hydrogen; halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen.

For example, in the above formulas, R ₁ , R ₂ , R ₃ , R ₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , and R ₂₈ are each independently hydrogen, F, Cl, Br, I, methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, trifluoromethyl group, tetrafluoroethyl group, phenyl group, naphthyl group, tetrafluorophenyl group, pyrrole group, Or a pyridine group.

For example, in the above formulas, R ₁ , R ₂ , R ₃ , R ₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , and R ₂₈ are each independently hydrogen, F, methyl group, ethyl group, propyl group, trifluoromethyl group, tetrafluoroethyl group, or phenyl group.

Specifically, the bicyclic sulfate-based compound may be represented by the formula 6 to 17:

<Formula 6> <Formula 7>

<Formula 8> <Formula 9

<Formula 10> <Formula 11>

<Formula 12> <Formula 13>

<Formula 14> <Formula 15>

<Formula 16> <Formula 17>

In this specification, a and b of "carbon number a to b" mean carbon number of a specific group. That is, the functional group may include carbon atoms from a to b. For example, an "alkyl group having 1 to 4 carbon atoms" means an alkyl group having 1 to 4 carbon atoms, that is, CH _3- , CH ₃ CH _2- , CH ₃ CH ₂ CH _2- , (CH ₃ ) ₂ CH-, CH ₃ CH ₂ CH ₂ CH ₂ —, CH ₃ CH ₂ CH (CH ₃ ) — and (CH ₃ ) ₃ C—.

The nomenclature for certain radicals may include mono-radical or di-radical, depending on the context. For example, if a substituent requires two link points for the rest of the molecule, the substituent should be understood as a diradical. For example, substituents specified as alkyl groups that require two linkage points include diradicals, such as —CH _{2 —} , —CH ₂ CH _{2 —} , —CH ₂ CH (CH ₃ ) CH _{2 —} , and the like. Other radical nomenclature, such as "achillene", clearly indicates that the radical is diradical.

As used herein, the term "alkyl group" or "alkylene group" means a branched or unbranched aliphatic hydrocarbon group. In one embodiment, the alkyl group may be substituted or unsubstituted. Alkyl group includes methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, etc. It is not necessarily limited to these, each of which may be optionally substituted or unsubstituted. In one embodiment, the alkyl group may have 1 to 6 carbon atoms. For example, an alkyl group having 1 to 6 carbon atoms may be, but is not limited to, methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, hexyl, and the like.

As used herein, the term "cycloalkyl group" means a fully saturated carbocycle ring or ring system. For example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl.

As used herein, the term "alkenyl group" refers to a hydrocarbon group containing 2 to 20 carbon atoms including at least one carbon-carbon double bond, an ethenyl group, 1-propenyl group, 2-propenyl group, 2-methyl- 1-propenyl group, 1-butenyl group, 2-butenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, and the like. In one embodiment, the alkenyl group may be substituted or unsubstituted. In one embodiment, the alkenyl group may have 2 to 40 carbon atoms.

As used herein, the term "alkynyl group" refers to a hydrocarbon group containing 2 to 20 carbon atoms including at least one carbon-carbon triple bond, an ethynyl group, 1-propynyl group, 1-butynyl group, 2-butynyl group And the like, but are not limited to these. In one embodiment, the alkynyl group may be substituted or unsubstituted. In one embodiment, the alkynyl group may have 2 to 40 carbon atoms.

As used herein, the term "aromatic" refers to a ring or ring system having a conjugated pi electronic system, and refers to a carbocyclic aromatic (eg phenyl group) and heterocyclic aromatic group (eg pyridine) Include. The term includes monocyclic or fused polycyclic rings (ie rings that share adjacent pairs of atoms) if the entire ring system is aromatic.

As used herein, the term "aryl group" means an aromatic ring or ring system in which the ring backbone contains only carbon (ie, two or more fused rings sharing two adjacent carbon atoms). If the aryl group is a ring system, then each ring in the system is aromatic. For example, aryl groups include, but are not limited to, phenyl groups, biphenyl groups, naphthyl groups, phenanthrenyl groups, naphthacenyl groups, and the like. The aryl group may be substituted or unsubstituted.

As used herein, the term “heteroaryl group” means an aromatic ring system having one ring or a plurality of fused rings and wherein one or more ring atoms is not carbon, ie a heteroatom. In a fused ring system, one or more heteroatoms may be present in only one ring. For example, heteroatoms include, but are not necessarily limited to, oxygen, sulfur and nitrogen. For example, the heteroaryl group is a furanyl group, a thienyl group, an imidazolyl group, a quinazolinyl group, a quinolinyl group, a quinolinyl group, an isoquinolinyl group, and a quinoxyl group. It may be a salinyl group (quinoxalinyl), pyridinyl (pyridinyl), pyrrolyl (pyrrolyl), oxazolyl group (oxazolyl), indolyl group, and the like, but is not limited thereto.

As used herein, the term "aralkyl group" and "alkylaryl group" means an aryl group connected as a substituent via an alkylene group, such as an aralkyl group having 7 to 14 carbon atoms, and the like. Benzyl group, 2-phenylethyl group, 3- Phenylpropyl group, naphthylalkyl group, but not limited to these. In one embodiment, the alkylene group is a lower alkylene group (ie, an alkylene group having 1 to 4 carbon atoms).

As used herein, a "cycloalkenyl group" is a carbocyclic ring or ring system having one or more double bonds, which is a ring system without an aromatic ring. For example, it is a cyclohexenyl group.

A "heterocyclyl group" herein is a non-aromatic ring or ring system comprising one or more heteroatoms in the ring backbone.

"Halogen" as used herein is a stable element belonging to Group 17 of the Periodic Table of the Elements, for example fluorine, chlorine, bromine or iodine, in particular fluorine and / or chlorine.

In the present specification, a substituent is derived by exchanging one or more hydrogens in another group or group in an unsubstituted mother group. Unless stated otherwise, when any functional group is considered to be "substituted," it is an alkyl group having 1 to 40 carbon atoms, an alkenyl group having 2 to 40 carbon atoms, a cycloalkyl group having 3 to 40 carbon atoms, a cycloalkyl having 3 to 40 carbon atoms. It is substituted with one or more substituents selected from alkenyl groups, alkyl groups having 1 to 40 carbon atoms, and aryl groups having 7 to 40 carbon atoms. When a functional group is described as "optionally substituted," it is meant that the functional group can be substituted with the substituents described above.

The content of the bicyclic sulfate-based compound represented by Formula 1 as an additive in the organic electrolyte may be 0.01 to 10% by weight based on the total weight of the organic electrolyte, but is not necessarily limited to this range, and an appropriate amount may be used if necessary. Can be. For example, the content of the bicyclic sulfate-based compound in the organic electrolyte may be 0.1 to 10% by weight based on the total weight of the organic electrolyte. For example, the content of the bicyclic sulfate-based compound in the organic electrolyte may be 0.1 to 7% by weight based on the total weight of the organic electrolyte. For example, the content of the bicyclic sulfate-based compound in the organic electrolyte may be 0.1 to 5% by weight based on the total weight of the organic electrolyte. For example, the content of the bicyclic sulfate-based compound in the organic electrolyte may be 0.1 to 3% by weight based on the total weight of the organic electrolyte. For example, the content of the bicyclic sulfate-based compound in the organic electrolyte may be 0.1 to 2% by weight based on the total weight of the organic electrolyte. For example, the content of the bicyclic sulfate-based compound in the organic electrolyte may be 0.2 to 1.5% by weight based on the total weight of the organic electrolyte. Further improved battery characteristics can be obtained within this content range.

In the organic electrolyte, the first lithium salt is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiAlO ₂ , LiAlCl ₄ , LiN (C _× F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) ( ₂ ≦ x ≦ 20, ₂ ≦ _y ≦ 20), LiCl, and LiI. have.

The concentration of the first lithium salt in the organic electrolyte solution may be 0.01 to 2.0 M, but is not necessarily limited to this range and an appropriate concentration may be used if necessary. Further improved battery characteristics can be obtained within this concentration range.

In the organic electrolyte solution, the organic solvent may include a low boiling point solvent. The low boiling point solvent means a solvent having a boiling point of 200 ° C. or lower at 25 ° C. and 1 atmosphere.

For example, the organic solvent may include one or more selected from the group consisting of dialkyl carbonates, cyclic carbonates, linear or cyclic esters, linear or cyclic amides, aliphatic nitriles, linear or cyclic ethers and derivatives thereof. Can be.

More specifically, the organic solvent is dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate (PC), ethylene carbonate (EC) , Butylene carbonate, ethyl propionate, ethyl butyrate, acetonitrile, succinitrile (SN), dimethyl sulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, gamma-butyrolactone and tetrahydrofuran It may include one or more selected from the group consisting of, but not necessarily limited to any low-solvent solvent that can be used in the art is possible.

The organic electrolyte described above may further include other additives in addition to the bicyclic sulfate-based compound. By further including other additives, the performance of the lithium battery may be further improved.

The additive additionally included in the organic electrolyte may be a cyclic carbonate compound, a second lithium salt, or the like.

For example, the organic electrolyte may further include a cyclic carbonate compound as an additive. Cyclic carbonate compounds used as additives include vinylene carbonate (VC); Vinylene carbonate substituted with one or more substituents selected from halogen, cyano group (CN) and nitro group (NO ₂ ); Vinyl ethylene carbonate (VEC); Vinylethylene carbonate substituted with one or more substituents selected from halogen, cyano group (CN) and nitro group (NO ₂ ); Fluoroethylene carbonate (FEC); And fluoroethylene carbonate substituted with one or more substituents selected from halogen, cyano group (CN) and nitro group (NO ₂ ); Can be selected from. As the organic electrolyte further includes a cyclic carbonate compound as an additive, the charge and discharge characteristics of the lithium battery employing the organic electrolyte may be further improved.

The content of the cyclic carbonate-based compound in the organic electrolyte may be 0.01 to 5% by weight based on the total weight of the organic electrolyte, but is not necessarily limited to this range and may be used in an appropriate amount as necessary. For example, the content of the cyclic carbonate-based compound in the organic electrolyte may be 0.1 to 5% by weight based on the total weight of the organic electrolyte. For example, the content of the cyclic carbonate-based compound in the organic electrolyte may be 0.1 to 4% by weight based on the total weight of the organic electrolyte. For example, the content of the cyclic carbonate-based compound in the organic electrolyte may be 0.1 to 3% by weight based on the total weight of the organic electrolyte. For example, the content of the cyclic carbonate-based compound in the organic electrolyte may be 0.1 to 2% by weight based on the total weight of the organic electrolyte. For example, the content of the cyclic carbonate-based compound in the organic electrolyte may be 0.2 to 2% by weight based on the total weight of the organic electrolyte. For example, the content of the cyclic carbonate-based compound in the organic electrolyte may be 0.2 to 1.5% by weight based on the total weight of the organic electrolyte. Further improved battery characteristics can be obtained within this content range.

For example, the organic electrolyte may further include a second lithium salt as an additive. The second lithium salt is a lithium salt that is distinguished from the first lithium salt, and the anion may be oxalate, PO ₂ F _2- , N (SO ₂ F) _2-, or the like. For example, the second lithium salt may be a compound represented by the following Chemical Formulas 18 to 25:

<Formula 18> <Formula 19>

<Formula 20> <Formula 21>

<Formula 22> <Formula 23>

<Formula 24> <Formula 25>

The content of the second lithium salt in the organic electrolyte solution may be 0.1 to 5% by weight based on the weight of the organic electrolyte solution species, but is not necessarily limited to this range and an appropriate amount may be used if necessary. For example, the content of the second lithium salt in the organic electrolyte may be 0.1 to 5 wt% based on the total weight of the organic electrolyte. For example, the content of the second lithium salt in the organic electrolyte may be 0.1 to 4% by weight based on the total weight of the organic electrolyte. For example, the content of the second lithium salt in the organic electrolyte may be 0.1 to 3% by weight based on the total weight of the organic electrolyte. For example, the content of the second lithium salt in the organic electrolyte may be 0.1 to 2% by weight based on the total weight of the organic electrolyte. For example, the content of the second lithium salt in the organic electrolyte may be 0.2 to 2% by weight based on the total weight of the organic electrolyte. For example, the content of the second lithium salt in the organic electrolyte may be 0.2 to 1.5 wt% based on the total weight of the organic electrolyte. Further improved battery characteristics can be obtained within this content range.

The organic electrolyte may be in liquid or gel state. The organic electrolyte may be prepared by adding the first lithium salt and the above-mentioned additives to the organic solvent.

Lithium battery according to another embodiment of the positive electrode; A negative electrode and the organic electrolytic solution according to the above are included. The lithium battery is not particularly limited in form, and includes lithium secondary batteries as well as lithium primary batteries such as lithium ion batteries, lithium ion polymer batteries, lithium sulfur batteries, and the like.

For example, in a lithium battery, the negative electrode may include graphite. For example, in a lithium battery, the anode may include a nickel-containing layered lithium transition metal oxide. For example, lithium battery is more than 3.80V It can have a high voltage of. For example, lithium battery is more than 4.0V It can have a high voltage of. For example, a lithium battery is more than 4.35V It can have a high voltage of.

For example, the lithium battery may be manufactured by the following method.

First, the anode is prepared.

For example, a cathode active material composition in which a cathode active material, a conductive material, a binder, and a solvent are mixed is prepared. The cathode active material composition is directly coated on a metal current collector to prepare a cathode plate. Alternatively, the cathode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on a metal current collector to prepare a cathode plate. The anode is not limited to the above enumerated forms and may be in any form other than the foregoing.

The positive electrode active material is a lithium-containing metal oxide, any one of those commonly used in the art can be used without limitation. For example, one or more of a complex oxide of metal and lithium selected from cobalt, manganese, nickel, and combinations thereof may be used, and specific examples thereof include Li _a A _1-b B _b D ₂ (the Wherein 0.90 ≦ a ≦ 1.8, and 0 ≦ b ≦ 0.5); Li _a E _1-b B _b 0 _2-c D _c (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); LiE _2-b B _b 0 _4-c D _c (wherein 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); Li _a Ni _1-bc Co _b B _c D _α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α ≦ 2); Li _a Ni _1-bc Co _b B _c 0 _2-α F _α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2); Li _a Ni _1-bc Co _b B _c O _2-α F ₂ (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2); Li _a Ni _1-bc Mn _b B _c D _α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α ≦ 2); Li _a Ni _1-bc Mn _b B _c O _2-α F _α (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2); Li _a Ni _1-bc Mn _b B _c O _2-α F ₂ (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, and 0 <α <2); Li _a Ni _b E _c G _d O ₂ (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, and 0.001 ≦ d ≦ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (wherein 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5, and 0.001 ≦ e ≦ 0.1); Li _a NiG _b O ₂ (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li _a CoG _b O ₂ (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li _a MnG _b O ₂ (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li _a Mn ₂ G _b O ₄ (wherein 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 ≦ f ≦ 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≦ f ≦ 2); Compounds represented by any of the formulas of LiFePO ₄ can be used:

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or combinations thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

For example, LiCoO ₂ , LiMn _x O _2x (x = 1, 2), LiNi _1-x Mn _x O _2x (0 <x <1), LiNi _1-xy Co _x Mn _y O ₂ (0 ≦ _x ≦ 0.5, 0 ≦ y ≦ 0.5), LiFePO _4, and the like.

Of course, those having a coating layer on the surface of the lithium-containing metal oxide may be used as the cathode active material, or may be used by mixing a compound having a coating layer on the surface of the lithium-containing metal oxide and the lithium-containing metal oxide. The coating layer may comprise a coating element compound of oxide of coating element, hydroxide, oxy hydroxide of coating element, oxycarbonate of coating element, or hydroxycarbonate of coating element. The compounds constituting these coating layers may be amorphous or crystalline. As the coating element included in the coating layer, Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr or a mixture thereof may be used. The coating layer forming process may use any coating method as long as it can be coated with the above compounds by a method that does not adversely affect the physical properties of the positive electrode active material (for example, spray coating or dipping method). Detailed descriptions thereof will be omitted since they can be understood by those skilled in the art.

Carbon black, graphite fine particles, etc. may be used as the conductive material, but is not limited thereto. Any conductive material may be used as long as it can be used as a conductive material in the art.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene and mixtures thereof, or styrene butadiene rubber-based polymers. It can be used, but not limited to these, any one that can be used as a binder in the art can be used.

As the solvent, N-methylpyrrolidone, acetone or water may be used, but not limited thereto, and any solvent may be used as long as it can be used in the art.

The content of the positive electrode active material, the conductive material, the binder, and the solvent is at a level commonly used in lithium batteries. At least one of the conductive material, the binder, and the solvent may be omitted according to the use and configuration of the lithium battery.

Next, a cathode is prepared.

For example, a negative electrode active material composition is prepared by mixing a negative electrode active material, a conductive material, a binder, and a solvent. The negative electrode active material composition is directly coated and dried on a metal current collector to prepare a negative electrode plate. Alternatively, the negative electrode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on a metal current collector to prepare a negative electrode plate.

The negative electrode active material may be used as long as it can be used as a negative electrode active material of a lithium battery in the art. For example, it may include one or more selected from the group consisting of lithium metal, a metal alloyable with lithium, a transition metal oxide, a non-transition metal oxide, and a carbon-based material.

For example, the metal alloyable with lithium is Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloy (The Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth Element or a combination thereof, not Si), Sn-Y alloy (Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element or combination thereof, and not Sn. ) And the like. As the element Y, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

For example, the transition metal oxide may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like.

For example, the non-transition metal oxide may be SnO ₂ , SiO _x (0 <x <2), or the like.

For example, the carbonaceous material may be crystalline carbon, amorphous carbon or a mixture thereof. The crystalline carbon may be graphite such as amorphous, plate-like, flake, spherical or fibrous natural graphite or artificial graphite, and the amorphous carbon may be soft carbon (low temperature calcined carbon) or hard carbon (hard). carbon, mesophase pitch carbide, calcined coke, and the like.

In the negative electrode active material composition, the conductive material and the binder may be the same as in the case of the positive electrode active material composition.

The content of the negative electrode active material, the conductive material, the binder, and the solvent is at a level commonly used in lithium batteries. At least one of the conductive material, the binder, and the solvent may be omitted according to the use and configuration of the lithium battery.

Next, a separator to be inserted between the positive electrode and the negative electrode is prepared.

The separator can be used as long as it is commonly used in lithium batteries. A low resistance to the ion migration of the electrolyte and excellent in the ability to hydrate the electrolyte can be used. For example, it is selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be in a nonwoven or woven form. For example, a rollable separator such as polyethylene or polypropylene may be used for a lithium ion battery, and a separator having excellent organic electrolyte solution impregnation ability may be used for a lithium ion polymer battery. For example, the separator may be manufactured according to the following method.

A separator composition is prepared by mixing a polymer resin, a filler, and a solvent. The separator composition may be directly coated and dried on top of the electrode to form a separator. Alternatively, after the separator composition is cast and dried on the support, the separator film separated from the support may be laminated on the electrode to form a separator.

The polymer resin used for preparing the separator is not particularly limited, and any materials used for the binder of the electrode plate may be used. For example, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate or mixtures thereof and the like can be used.

Next, the above-mentioned organic electrolyte solution is prepared.

As shown in FIG. 7, the lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The positive electrode 3, the negative electrode 2, and the separator 4 described above are wound or folded to be accommodated in the battery case 5. Subsequently, the organic electrolyte is injected into the battery case 5 and sealed with a cap assembly 6 to complete the lithium battery 1. The battery case may be cylindrical, rectangular, thin film, or the like.

The separator may be disposed between the positive electrode and the negative electrode to form a battery structure. The battery structure is stacked in a bi-cell structure, and then impregnated in the organic electrolyte, and the resultant is accommodated in a pouch and sealed to complete the lithium battery.

A plurality of battery structures are stacked to form a battery pack, and the battery pack may be used in any device requiring high capacity and high power. For example, it can be used in notebooks, smartphones, electric vehicles and the like.

In addition, the lithium battery may be used in an electric vehicle (EV) because of its excellent life characteristics and high rate characteristics. For example, it may be used in a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV). It can also be used in applications where a large amount of power storage is required. For example, it can be used for electric bicycles, power tools and the like.

The present invention is described in more detail through the following examples and comparative examples. However, the examples are provided to illustrate the present invention, and the scope of the present invention is not limited only to these examples.

(Synthesis of additives)

Preparation Example 1 Synthesis of Compound of Formula 3

The compound of formula 3 may be prepared according to the following reaction scheme 1.

<Reaction Scheme 1>

(Synthesis of Compound A)

68.0 g (0.499 mol) of pentaerythritol and 100 g of molecular sieve (Type 4A) were added to a 1: 1 volume ratio mixed solvent of tetrahydrofuran (THF) and dichloromethane (DCM, CH ₂ Cl ₂ ). And reflux for 20 minutes. Then, 110 ml (2.8 equiv., 1.40 mol) of thionyl chloride (SOCl ₂ ) were added and refluxed for 8 hours until all pentaerythritol was reacted to obtain a light yellow solution. The resulting pale yellow solution was filtered and concentrated to give a residue containing a pale yellow solid. 1 L of saturated sodium hydrogen carbonate (saturated NaHCO ₃ ) solution was added directly to the obtained residue at a rate that minimizes effervescence to obtain a suspension. The resulting suspension was stirred vigorously for 20 minutes. The suspension was then filtered and the filtered solid was added to 1 L of purified water to prepare a mixture. The prepared mixture was stirred vigorously for 20 minutes, then filtered through suction and dried in air to recover 104.61 g (0.458 mol, 92%) of compound A.

1 H and 13 C NMR data of Compound A were in agreement with literature values.

(Synthesis of Compound B)

As indicated in Reaction Scheme 1, Compound B, represented by Formula 6, was synthesized from Compound A according to the method disclosed in Canadian Journal of Chemistry, 79, 2001, page 1042.

The synthesized compound was recrystallized in a mixed solvent of 1,2-dichloroethane and acetonitrile in a 2: 1 volume ratio, and used for preparing an electrolyte solution.

<Formula 6>

(Production of organic electrolyte)

Example 1: 1.0 wt% of SEI-1316

To a 3: 5: 2 volume ratio mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), 0.90 M LiPF ₆ and 1% by weight of a compound represented by the following formula (6) are added as a lithium salt: To prepare an organic electrolyte solution.

<Formula 6>

Example 2: 1.0 wt% SEI-1316 + 0.5 wt% VC

An organic electrolyte was prepared in the same manner as in Example 1, except that the additive was changed to 1% by weight of the compound of Formula 6 and 0.5% by weight of vinylene carbonate (VC).

Example 3: SEI-1316 0.5 wt%

An organic electrolyte was prepared in the same manner as in Example 1, except that the content of the compound of Formula 6, which is an additive, was changed to 0.5 wt%.

Comparative Example 1

An organic electrolyte solution was prepared in the same manner as in Example 1, except that the compound of Chemical Formula 6, which was an additive, was not added.

(Manufacture of Lithium Battery)

Example 4

(Cathode production)

98% by weight of artificial graphite (BSG-L, Tianjin BTR New Energy Technology Co., Ltd.), 1.0% by weight of styrene-butadiene rubber (SBR) binder (ZEON) and 1.0% by weight of carboxymethyl cellulose (CMC, NIPPON A & L) After mixing, the mixture was added to distilled water and stirred for 60 minutes using a mechanical stirrer to prepare a negative electrode active material slurry. The slurry was applied on a 10 μm thick copper current collector using a doctor blade to a thickness of about 60 μm, dried for 0.5 hours in a hot air dryer at 100 ° C., and then dried again under vacuum, 120 ° C. for 4 hours, and rolled. (roll press) to prepare a negative electrode plate.

(Anode manufacturing)

LiNi _1/3 Co _1/3 Mn _1/3 O ₂ 97.45% by weight, 0.5% by weight of artificial graphite (SFG6, Timcal) powder as conductive material, 0.7% by weight of carbon black (Ketjenblack, ECP), modified acrylonitrile rubber ( BM-720H, Zeon Corporation) 0.25% by weight, polyvinylidene fluoride (PVdF, S6020, Solvay) 0.9% by weight, polyvinylidene fluoride (PVdF, S5130, Solvay) by mixing N-methyl-2 -Pyrrolidone solvent and then stirred for 30 minutes using a mechanical stirrer to prepare a cathode active material slurry. The slurry was applied on a 20 μm thick aluminum current collector using a doctor blade, dried about 0.5 μm in a hot air dryer at 100 ° C., and then dried again under vacuum, 120 ° C. for 4 hours, and rolled. (roll press) to prepare a positive electrode plate.

A lithium battery was manufactured using a 14 μm-thick polyethylene separator coated with a ceramic on the positive electrode side as a separator and the organic electrolyte solution prepared in Example 1 as an electrolyte solution.

Examples 5-6

A lithium battery was manufactured in the same manner as in Example 4, except that the organic electrolytes prepared in Examples 2 to 3 were used instead of the organic electrolytes prepared in Example 1.

Comparative Example 2

A lithium battery was manufactured in the same manner as in Example 4, except that the organic electrolyte prepared in Comparative Example 1 was used instead of the organic electrolyte prepared in Example 1.

Evaluation Example 1: Evaluation of Charge and Discharge Characteristics at 4.25V Room Temperature (25 ° C)

The lithium batteries prepared in Examples 4 to 6 and Comparative Example 2 were charged with a constant current until the voltage reached 4.25V (vs. Li) at a current of 0.1C at 25 ° C., and then maintained at 4.25V in the constant voltage mode. While cut-off at a current of 0.05C rate. Subsequently, it discharged at the constant current of 0.1C rate until the voltage reached 2.8V (vs. Li) at the time of discharge (chemical conversion step, 1 ^st cycle).

The lithium battery, which has undergone the 1 ^st cycle of the formation step, is charged at a constant current until the voltage reaches 4.25 V (vs. Li) at a current of 0.2 C at 25 ° C., followed by 0.05 C rate while maintaining 4.25 V in the constant voltage mode. Cut-off at the current of Subsequently, it discharged at the constant current of 0.2C rate until the voltage reached 2.8V (vs. Li) at the time of discharge (chemical conversion step, 2nd cycle).

The lithium battery undergoing the formation step is charged at a constant current until the voltage reaches 4.25V (vs. Li) at a current of 1.0C rate at 25 ° C, and then cutoff at a current of 0.05C rate while maintaining 4.25V in the constant voltage mode. (cut-off). Subsequently, the cycle of discharging at a constant current of 1.0 C rate was repeated to 380 ^th cycle until the voltage reached 2.75 V (vs. Li) at the time of discharge.

In all of the above charge / discharge cycles, a stop time of 10 minutes was allowed after one charge / discharge cycle.

Some of the charge and discharge test results are shown in Table 1 and FIGS. 1 and 2. The capacity retention rate at 400 ^th cycle is defined by Equation 1 below.

<Equation 1>

Capacity retention ratio = [discharge capacity in 380 ^th cycle / 1 discharge capacity in ^1st cycle] * 100

Discharge Capacity at 380 ^th Cycle [mAh / g] Capacity retention at 380 ^th cycle [%] Example 4 202 75 Example 5 228 82 Comparative Example 2 173 63

As shown in Table 1, Figure 1 and 2, the lithium battery of Examples 4 to 5 including the additive of the present invention has a discharge capacity and life characteristics at room temperature compared to the lithium battery of Comparative Example 2 without the additive Significantly improved.

Evaluation Example 2: Evaluation of Charge and Discharge Characteristics at 4.25V High Temperature (45 ° C)

The charge and discharge characteristics of the lithium batteries prepared in Examples 4 to 6 and Comparative Example 2 were evaluated in the same manner as in Evaluation Example 1, except that the charge and discharge temperature was changed to 45 ° C. However, the charge / discharge cycle was changed to 200 cycles.

Some of the charge and discharge test results are shown in Table 2 and FIGS. 3 to 4. The capacity retention rate at 200 ^th cycle is defined by Equation 2 below.

<Equation 2>

Capacity maintenance rate = [200 discharge capacity / 1 ^st cycle discharge capacity at in ^th cycle] × 100

Discharge Capacity at 200 ^th Cycle [mAh / g] Capacity retention at 200 ^th cycle [%] Example 4 249 83 Example 5 255 84 Comparative Example 2 235 79

As shown in Table 2, FIG. 3 and FIG. 4, the lithium batteries of Examples 4 to 5 including the additive of the present invention have higher discharge capacity and lifetime characteristics at higher temperatures than those of Comparative Example 2 without the additive. Significantly improved.

Evaluation Example 3: Evaluation of Charge and Discharge Characteristics at 4.30V Room Temperature (25 ° C)

The lithium batteries prepared in Example 4 and Comparative Example 2 were charged at a constant current until the voltage reached 4.30 V (vs. Li) at a current of 0.1 C at 25 ° C., followed by 0.05 while maintaining 4.30 V in the constant voltage mode. Cut-off at current of C rate. Subsequently, it discharged at the constant current of 0.1C rate until the voltage reached 2.8V (vs. Li) at the time of discharge (chemical conversion step, 1 ^st cycle).

The lithium battery, which has undergone the 1 ^st cycle of the chemical conversion step, is charged at a constant current until the voltage reaches 4.30 V (vs. Li) at a current of 0.2 C at 25 ° C., followed by 0.05 C rate while maintaining 4.30 V in the constant voltage mode. Cut-off at the current of Subsequently, it discharged at the constant current of 0.2C rate until the voltage reached 2.8V (vs. Li) at the time of discharge (chemical conversion step, 2nd cycle).

The lithium battery undergoing the formation step was charged at a constant current until the voltage reached 4.30 V (vs. Li) at a current of 0.5 C at 25 ° C., and then cut-off at a current of 0.05 C while maintaining 4.30 V in the constant voltage mode. (cut-off). Subsequently, the cycle of discharging at a constant current of 1.0 C rate was repeated to 250 ^th cycle until the voltage reached 2.75 V (vs. Li) at the time of discharge.

In all of the above charge / discharge cycles, a stop time of 10 minutes was allowed after one charge / discharge cycle.

Some of the charge and discharge test results are shown in Table 3 and FIG. 5. The capacity retention rate at 250 ^th cycle is defined by Equation 3 below.

<Equation 3>

Capacity maintenance rate = [250-discharge capacity / 1 ^st cycle discharge capacity at in ^th cycle] × 100

Discharge Capacity at 250 ^th Cycle [mAh / g] Capacity retention at 250 ^th cycle [%] Example 4 171 84 Comparative Example 2 154 77

As shown in Table 3 and FIG. 5, the lithium battery of Example 4 including the additive of the present invention was significantly improved in discharge capacity and life characteristics at room temperature compared to the lithium battery of Comparative Example 2 without the additive.

Evaluation Example 4: Evaluation of 4.30V High Temperature (45 ° C) Charge-Discharge Characteristics

The charge and discharge characteristics of the lithium batteries manufactured in Example 4 and Comparative Example 2 were evaluated in the same manner as in Evaluation Example 3, except that the charge and discharge temperature was changed to 45 ° C. However, the charge / discharge cycle was changed to 200 cycles.

Some of the charge and discharge test results are shown in Table 4 and FIG. 6. The capacity retention rate at 200 ^th cycle is defined by Equation 4 below.

<Equation 4>

Capacity maintenance rate = [200 discharge capacity / 1 ^st cycle discharge capacity at in ^th cycle] × 100

Discharge Capacity at 200 ^th Cycle [mAh / g] Capacity retention at 200 ^th cycle [%] Example 4 189 90 Comparative Example 2 174 84

As shown in Table 4 and FIG. 6, the lithium battery of Example 4 including the additive of the present invention was significantly improved in discharge capacity and lifespan characteristics at high temperatures compared to the lithium battery of Comparative Example 3 without the additive.

Evaluation Example 5: 60 ° C High Temperature Stability Evaluation

The lithium batteries prepared in Examples 4 to 6 and Comparative Example 2 were charged with constant current to 4.3 V at a rate of 0.5 C in a 1st cycle at room temperature (25 ° C.), and then maintained at 4.3 V while maintaining current at 4.3 V. Constant voltage charge was carried out until it became 0.05C, and it discharged constant current to 2.8V at the speed of 0.5C.

The 2 ^nd cycle was constant current charged up to 4.3V at a rate of 0.5 C, then constant voltage charged until the current became 0.05C while maintaining at 4.3V, and constant current discharged to 2.8V at a rate of 0.2C.

The 3 ^rd cycle was constant current charged up to 4.3V at a rate of 0.5C, followed by constant voltage charge until the current reached 0.05C while maintaining 4.3V, and constant current discharged up to 2.80V at a rate of 0.2C. The discharge capacity at the 3 ^rd cycle was regarded as a standard capacity.

After charging to 4.30 V at a rate of 0.5 C in a 4th cycle, and then constant voltage charging until the current reaches 0.05 C while maintaining at 4.30 V,

After storing the charged battery in an oven at 60 ° C. for 10 days and 30 days, the battery was taken out and discharged in a 4th cycle up to 2.80 V at a rate of 0.1 C.

Some of the charge / discharge evaluation results are shown in Table 5 below. Capacity retention rate after high temperature storage is defined by the following equation (5).

<Equation 5>

Capacity retention rate after high temperature storage [%] = [discharge capacity after high temperature standing in 4th cycle / standard capacity] × 100 (the standard capacity is the discharge capacity in 3 ^rd cycle)

Capacity retention after 10 days storage [%] Capacity retention after 20 days storage [%] Example 6 91 87 Comparative Example 2 90 86

As shown in Table 5, the lithium battery of Example 6 including the organic electrolyte solution of the present invention was significantly increased in high temperature stability compared to the lithium battery of Comparative Example 2 not containing the organic electrolyte solution of the present invention.

Evaluation Example 6 DC-IR Evaluation After High Temperature Storage At 60 ° C

Among the lithium batteries prepared in Examples 4 to 6 and Comparative Example 2, the cells which were not stored in a 60 ° C. oven and stored in a 60 ° C. oven for 10 days and 30 days at room temperature (25 ° C.) were taken out of a direct current. Resistance (DC-IR) was measured by the following method.

After charging at 50% of SOC (state of charge) with a current of 0.5C in 1st cycle, cut off at 0.02C, and then rest for 10 minutes,

After 30 seconds of constant current discharge at 0.5 C, the battery is allowed to rest for 30 seconds, and then charged for 30 seconds at a constant current of 0.5 C for 10 minutes,

After 30 seconds of constant current discharge at 1.0 C, the battery was allowed to rest for 30 seconds, followed by 1 minute constant current charge at 0.5 C, followed by 10 minutes of rest.

After 30 seconds of constant current discharge at 2.0 C, after 30 seconds of rest, 2 minutes of constant current charging at 0.5 C and 10 minutes of rest,

After 30 seconds of constant current discharge at 3.0 C, the battery was allowed to rest for 30 seconds, followed by 2 minutes of constant current charging at 0.5 C, followed by 10 minutes of rest.

The average voltage drop over 30 seconds for each C-rate is the DC voltage.

A part of the DC resistance increase rate calculated from the measured initial DC resistance and the DC resistance after high temperature storage is shown in Table 6 below. DC resistance increase rate is represented by the following equation (6).

<Equation 6>

DC resistance increase rate [%] = [DC resistance after high temperature storage / initial DC resistance] × 100

DC resistance increase after 10 days storage [%] DC resistance increase after 20 days storage [%] Example 6 113 125 Comparative Example 2 122 137

As shown in Table 6, the lithium battery of Example 6 including the organic electrolytic solution of the present invention decreased the increase rate of DC resistance after high temperature storage as compared to the lithium battery of Comparative Example 2 containing no organic electrolytic solution of the present invention. .

Claims (19)

First lithium salt; Organic solvents; And an organic electrolyte comprising a bicyclic sulfate-based compound represented by Formula 1 below:
<Formula 1>

Where
A ₁ , A ₂ , A ₃ and A ₄ are covalently bonded to each other independently; An alkylene group having 1 to 5 carbon atoms unsubstituted or substituted with a substituent; Carbonyl group; Or a sulfinyl group, provided that A ₁ and A ₂ are not covalent bonds at the same time, and A ₃ and A ₄ are not covalent bonds at the same time. The method according to claim 1, wherein at least one of A ₁ , A ₂ , A _3, and A ₄ is an unsubstituted alkyl group having 1 to 5 carbon atoms or a substituted alkyl group having 1 to 5 carbon atoms, and substituted with 1 to 5 carbon atoms. Alkyl group having 1 to 20 carbon atoms substituted or unsubstituted with halogen, alkyl group having 2 to 20 carbon atoms substituted or unsubstituted with halogen, alkynyl group having 2 to 20 carbon atoms substituted or unsubstituted with halogen , A cycloalkenyl group having 3 to 20 carbon atoms substituted or unsubstituted with halogen, a heterocyclyl group having 3 to 20 carbon atoms substituted or unsubstituted with halogen, an aryl group having 6 to 40 carbon atoms substituted or unsubstituted with halogen, halogen A substituted or unsubstituted heteroaryl group having 2 to 40 carbon atoms, or at least one organic electrolyte solution containing at least one heteroatom. The method according to claim 1, wherein at least one of A ₁ , A ₂ , A _3, and A ₄ is an unsubstituted alkyl group having 1 to 5 carbon atoms or a substituted alkyl group having 1 to 5 carbon atoms, and substituted with 1 to 5 carbon atoms. The substituent of the alkylene group of 5 is halogen, methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, trifluoromethyl group, tetrafluoroethyl group, phenyl group, naphthyl group, tetrafluorophenyl group, pyrrolyl group Or an organic electrolyte which is a pyridinyl group. According to claim 2, wherein the substituted C 1-5 alkylene group is substituted with a polar functional group containing at least one heteroatom, wherein the polar functional group containing the heteroatom is -F, -Cl, -Br, -I , -C (= O) OR ¹⁶ , -OR ¹⁶ , -OC (= O) OR ¹⁶ , -R ¹⁵ OC (= O) OR ¹⁶ , -C (= O) R ¹⁶ , -R ¹⁵ C (= O R ¹⁶ , -OC (= O) R ¹⁶ , -R ¹⁵ OC (= O) R ¹⁶ , -C (= O) -OC (= O) R ¹⁶ , -R ¹⁵ C (= O) -OC ( = O) R ¹⁶ , -SR ¹⁶ , -R ¹⁵ SR ¹⁶ , -SSR ¹⁶ , -R ¹⁵ SSR ¹⁶ , -S (= O) R ¹⁶ , -R ¹⁵ S (= O) R ¹⁶ , -R ¹⁵ C (= S) R ¹⁶ , -R ¹⁵ C (= S) SR ¹⁶ , -R ¹⁵ SO ₃ R ¹⁶ , -SO ₃ R ¹⁶ , -NNC (= S) R ¹⁶ , -R ¹⁵ NNC (= S) R ¹⁶ , -R ¹⁵ N = C = S, -NCO, -R ¹⁵ -NCO, -NO ₂ , -R ¹⁵ NO ₂ , -R ¹⁵ SO ₂ R ¹⁶ , -SO ₂ R ¹⁶ ,

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, And

At least one selected from the group consisting of,
R ¹¹ and R ¹⁵ are each independently an alkylene group having 1 to 20 carbon atoms substituted or unsubstituted with halogen; Alkenylene group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; An alkynylene group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; A cycloalkylene group having 3 to 12 carbon atoms unsubstituted or substituted with halogen; An arylene group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Heteroarylene group having 2 to 40 carbon atoms unsubstituted or substituted with halogen; An alkylarylene group having 7 to 15 carbon atoms unsubstituted or substituted with halogen; Or an aralkylene group having 7 to 15 carbon atoms unsubstituted or substituted with halogen,
R ¹² , R ¹³ , R ¹⁴ and R ¹⁶ are each independently hydrogen; halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Alkenyl groups having 2 to 20 carbon atoms unsubstituted or substituted with halogen; An alkynyl group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; A cycloalkyl group having 3 to 12 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; C2-C40 heteroaryl group unsubstituted or substituted with halogen; An alkylaryl group having 7 to 15 carbon atoms unsubstituted or substituted with halogen; Trialkylsilyl group having 7 to 15 carbon atoms unsubstituted or substituted with halogen; Or an organic electrolyte having 7 to 15 carbon atoms which is unsubstituted or substituted with halogen. The organic electrolyte of claim 1, wherein the bicyclic sulfate-based compound is represented by the following Chemical Formulas 2-3:
<Formula 2><Formula3>

In the above formulas,
B ₁ , B ₂ , B ₃ , B ₄ , D ₁ , and D ₂ are, independently from each other, —C (E ₁ ) (E ₂ ) —; Carbonyl group; Or a sulfinyl group,
E ₁ and E ₂ are independently of each other hydrogen; halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Alkenyl groups having 2 to 20 carbon atoms unsubstituted or substituted with halogen; An alkynyl group having 2 to 20 carbon atoms which is unsubstituted or substituted with halogen; A cycloalkenyl group having 3 to 20 carbon atoms unsubstituted or substituted with halogen; A heterocyclyl group having 3 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen. The method of claim 5, wherein E ₁ and E ₂ are independently of each other hydrogen; halogen; An alkyl group having 1 to 10 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Or an organic electrolytic solution which is a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen. The method of claim 5, wherein E ₁ and E ₂ are independently of each other hydrogen, F, Cl, Br, I, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, trifluoromethyl, At least one organic electrolyte solution selected from the group consisting of a tetrafluoroethyl group, a phenyl group, a naphthyl group, a tetrafluorophenyl group, a pyrrolyl group, and a pyridinyl group. The organic electrolyte of claim 1, wherein the bicyclic sulfate-based compound is represented by the following Chemical Formulas 4 to 5:
<Formula 4><Formula5>

In the above formulas,
R ₁ , R ₂ , R ₃ , R ₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , and R ₂₈ are each independently hydrogen; halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 40 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 40 carbon atoms unsubstituted or substituted with halogen. The method of claim 8, wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , and R ₂₈ are each independently hydrogen, F , Cl, Br, I, methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, trifluoromethyl group, tetrafluoroethyl group, phenyl group, naphthyl group, tetrafluorophenyl group, pyrrolyl group, or Organic electrolyte which is a pyridinyl group. The organic electrolyte of claim 1, wherein the bicyclic sulfate-based compound is represented by the following Chemical Formulas 6 to 17:
<Formula 6><Formula7>

<Formula 8><Formula 9

<Formula 10><Formula11>

<Formula 12><Formula13>

<Formula 14><Formula15>

<Formula 16><Formula17>

The organic electrolyte of claim 1, wherein the bicyclic sulfate-based compound is present in an amount of 0.01 to 10 wt% based on the total weight of the organic electrolyte. The method of claim 1, wherein the first lithium salt in the organic electrolyte is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO _{In the group} consisting of ₃ , LiAlO ₂ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) ( ₂ ≦ _x ≦ ₂₀ , ₂ ≦ _y ≦ 20), LiCl and LiI An organic electrolyte containing at least one selected. The method of claim 1, further comprising a cyclic carbonate compound, wherein the cyclic carbonate compound is vinylene carbonate (VC); Vinylene carbonate substituted with one or more substituents selected from halogen, cyano group (CN) and nitro group (NO ₂ ); Vinyl ethylene carbonate (VEC); Vinylethylene carbonate substituted with one or more substituents selected from halogen, cyano group (CN) and nitro group (NO ₂ ); Fluoroethylene carbonate (FEC); And fluoroethylene carbonate substituted with one or more substituents selected from halogen, cyano group (CN) and nitro group (NO ₂ ); Organic electrolyte solution selected from. The organic electrolyte of claim 13, wherein the content of the cyclic carbonate compound is 0.01 to 5 wt% based on the total weight of the organic electrolyte. The organic electrolyte of claim 1, further comprising a second lithium salt represented by the following Chemical Formulas 18 to 25:
<Formula 18><Formula19>

<Formula 20><Formula21>

<Formula 22><Formula23>

<Formula 24><Formula25>

. The organic electrolyte of claim 15, wherein the content of the second lithium salt is 0.1 to 5 wt% based on the weight of the organic electrolyte species. anode; cathode; And
A lithium battery comprising the organic electrolyte solution according to any one of claims 1 to 16. The lithium battery of claim 17, wherein the anode comprises a nickel-containing layered structure lithium transition metal oxide. The lithium battery of claim 17, wherein the lithium battery has a high voltage of 3.8V or higher.

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