KR20170018739A - Electrolyte for lithium battery and Lithium battery including the electrolyte - Google Patents

Abstract

Disclosed are an electrolyte for a lithium battery including: a compound expressed by Chemical Formula 1; lithium salt; and an organic solvent and a lithium battery including the same. In chemical formula 1, X is a halogen atom; R_1 and R_2 are independently substituted or unsubstituted C1-C20 alkyl groups, independently substituted or unsubstituted C2-C20 akenyl groups, substituted or unsubstituted C2-C20 akynyl groups, substituted or unsubstituted C6-C20 aryl group, or substituted or unsubstituted heteroaryl groups; and R_1 and R_2 can form a ring by being connected to each other.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte for a lithium battery and a lithium battery including the electrolyte,

The present invention relates to an electrolyte for a lithium battery and a lithium battery including the same.

Lithium batteries are used as power sources for portable electronic devices such as video cameras, mobile phones, and notebook computers. The rechargeable lithium secondary battery has three times higher energy density per unit weight than conventional lead batteries, nickel-cadmium batteries, nickel metal hydride batteries and nickel-zinc batteries.

Since the lithium battery operates at a high driving voltage, an aqueous electrolyte having high reactivity with lithium can not be used. Generally, an organic electrolyte is used for a lithium battery. The organic electrolyte is prepared by dissolving a lithium salt in an organic solvent. It is preferable that the organic solvent is stable at a high voltage, has a high ionic conductivity and a high dielectric constant, and has a low viscosity.

As the lithium salt, LiPF ₆ is mainly used. However, LiPF6 reacts with the organic solvent of the electrolyte to promote the depletion of the solvent and generate a large amount of gas. When a polar non-aqueous solvent based on carbonate is used as an organic solvent, an irreversible reaction proceeds in excess of charge due to a side reaction between the cathode / anode and the electrolyte at the time of initial charging. A passivation layer such as a solid electrolyte interface layer (SEI layer) is formed on the surface of the cathode by the irreversible reaction. The SEI layer prevents decomposition of the electrolyte during charging and discharging and functions as an ion tunnel. The lifetime of the lithium battery can be improved as the SEI layer has high stability and low resistance.

Various additives are used for the stabilization of the SEI layer. However, the SEI layer formed using conventional conventional additives easily deteriorated at high temperatures. That is, the SEI layer was degraded in stability at high temperature. Thus, there is a need for an electrolyte capable of inhibiting side reactions of LiPF ₆ and forming SEIs with improved high temperature stability.

One aspect is to provide an electrolyte for a new lithium battery.

Another aspect is to provide a lithium battery including the electrolyte.

On one side

A compound represented by Formula 1 below; Lithium salts; And an electrolyte for a lithium battery comprising an organic solvent:

≪ Formula 1 >

Wherein X is a halogen atom, R ₁ and R ₂ A substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C1-C20 alkyl group, A substituted C2-C20 heteroaryl group, and R ₁ and R ₂ may be connected to each other to form a ring.

Anodic according to another aspect; cathode; And a lithium battery including the electrolyte described above.

The use of an electrolyte according to an embodiment improves cycle characteristics at a high temperature and makes it possible to manufacture a lithium battery which can be driven at a high operating voltage.

Fig. 1 shows the non-discharge capacity change at 4.40 V in the lithium battery produced according to Example 3-4 and Comparative Example 2. Fig.
Fig. 2 shows the non-discharge capacity change at 4.45 V in the lithium battery produced according to Examples 3, 4 and 9 and Comparative Example 2. Fig.
3 shows the capacity retention rate change at 4.45 V in the lithium battery produced according to Examples 3, 4 and 9 and Comparative Example 2. [
4 is a schematic diagram of a lithium battery according to an exemplary embodiment.

Hereinafter, a lithium battery electrolyte according to exemplary embodiments and a lithium battery including the same will be described in more detail.

An electrolyte for a lithium battery according to an embodiment includes: a compound represented by the following formula (1); Lithium salts; And organic solvents.

≪ Formula 1 >

Wherein X is a halogen atom, R ₁ and R ₂ A substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C1-C20 alkyl group, A substituted C2-C20 heteroaryl group, and R ₁ and R ₂ may be connected to each other to form a ring.

In the above formula (1), the halogen atom is chlorine, fluorine, or iodine, and fluorine is most stable.

The compound represented by Formula 1 may be a compound represented by Formula 1a.

<Formula 1a>

In the formula (1a), R ₁ And R ₂ A substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C1-C20 alkyl group, A substituted C2-C20 heteroaryl group,

R ¹ and R ² may be connected to each other to form a ring.

In the general formulas (1) and (1a), R ₁ and R ₂ are connected to each other to form a substituted or unsubstituted C 2 to C 5 alkylene group.

The said R ₁ and R ₂ are connected to each other _{-CH 2 -CH 2 -, -CH 2} -C (CH 3) 2 -CH 2 - or _{-C (CH 3) 2 -C (} CH 3) 2 - group forming can do.

The compound is selected from compounds represented by the following formulas.

(2)

In Formula 2, R ₃ To R ₆ independently represent hydrogen, a C1-C10 alkyl group, a C6-C20 aryl group, a halogen atom, a cyano group, a hydroxyl group, a C2-C20 heteroaryl group, a C6- Lt; RTI ID = 0.0 &gt; C20 &lt; / RTI &gt; heterocyclic group,

(3)

In the above formula (3), R ₇ To R ₁₂ independently represent hydrogen, a C 1 -C 10 alkyl group, a C 6 -C 20 aryl group, a halogen atom, a cyano group, a hydroxyl group, a C 2 -C 20 heteroaryl group, a C 6 -C 20 carbon ring group, Lt; RTI ID = 0.0 &gt; C20 &lt; / RTI &gt;

The compound is at least one selected from a compound represented by the following general formula (4), a compound represented by the general formula (5), a compound represented by the general formula (6) and a compound represented by the general formula (7).

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

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

The content of the compound represented by the general formula (1) as an additive in the electrolyte is 0.01 to 10% by weight, for example 0.001 to 5% by weight, based on the total weight of the electrolyte. The content of the compound represented by the chemical formula may be, for example, 0.1 to 3% by weight, specifically 0.1 to 0.25% by weight, but is not necessarily limited to such a range, and an appropriate amount may be used if necessary.

The content of the lithium salt in the electrolyte is 0.5 to 3 wt%, for example, 0.5 to 1.5 wt%, based on the total weight of the electrolyte. When the content of the lithium salt is within the above range, the lifetime characteristics of the lithium battery are improved without increasing the internal resistance of the electrolyte.

The lithium salt may be any lithium salt generally used in the art in the production of electrolytes. For example, the lithium salt, for example, _{LiPF 6, LiBF 4, LiSbF 6} , LiAsF 6, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, Li (FSO 2) 2 N, LiC _{4 F 9 SO 3, LiAlO 2} , LiAlCl 4, LiN (C x F 2x +1 SO 2) (C y F 2y +1 SO 2) (x, y is 1 to 20), LiCl, LiI or a And mixtures thereof. The concentration of such a general lithium salt may be 0.01 to 2.0 M in the electrolyte, but is not necessarily limited to this range, and an appropriate concentration may be used if necessary. Further improved battery characteristics within the above range of concentration can be obtained.

The reason why the compound of Formula 1 is added to the electrolyte to improve the performance of the lithium battery will be described in more detail below. However, the present invention is not limited to the following description .

The improvement in cycle life performance in a lithium battery when the compound of formula (1) is added to an electrolyte can be explained as follows.

First, the compound of the formula (1) is a phosphite-based compound and stabilizes the LiPF6 salt of the electrolyte when the charge and discharge cycle proceeds, thereby preventing decomposition. Second, the compound of formula (1) has an oxidation potential lower than that of the solvent, so that the SEI film is formed on the surface of the anode before the electrolyte is decomposed, thereby preventing the electrolyte from being oxidized on the anode.

Third, the product (i.e., phosphate) obtained by oxidation of the compound of Formula 1 at the anode surface is transferred to the cathode and participates in the formation of the SEI film resulting from the reduction of the phosphate on the cathode.

The compound of Formula 1 has an electron-accepting fluorine substituent directly bonded to phosphorus (P (III)), which is a central atom, and can improve the stability of an SEI film existing on the anode at a high voltage of 4.45 V or higher.

As a result, the compound of Formula 1 can form an SEI layer on the surface of the anode, or a protective layer can be formed on the surface of the anode. Since the compound has improved thermal stability, oxidation stability at high temperature is excellent. Life characteristics can be improved. Further, a lithium battery having excellent stability at a high voltage of 4.4 V or more, for example, 4.45 V or more can be manufactured.

The substituent on the substituted C 1 -C 20 alkyl group, the substituted C 2 -C 20 alkenyl group, the substituted C 2 -C 20 alkynyl group, the substituted C 6 -C 20 aryl group, or the substituted C 2 -C 20 heteroaryl group is preferably a halogen, a methyl group, May be, but not necessarily limited to, a methyl group, an isopropyl group, a butyl group, a tert-butyl group, a trifluoromethyl group, a tetrafluoroethyl group, a phenyl group, a naphthyl group, a tetrafluorophenyl group, a pyrrolyl group and a pyridinyl group And can be used as substituents of alkylene groups in the art.

The organic solvent in the electrolyte may comprise a low boiling solvent. The low boiling point solvent means a solvent having a boiling point of 200 캜 or less at 25 캜 and 1 atm.

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 do.

More specifically, the organic solvent is selected from the group consisting of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate ), Fluoroethylene carbonate (FEC), butylene carbonate, ethyl propionate, ethyl butyrate, acetonitrile, succinonitrile (SN), dimethylsulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, Gamma -butyrolactone, tetrahydrofuran, gamma-butyrolactone, and tetrahydrofuran, but not always limited thereto, and any low boiling point solvent that can be used in the art can be used.

A lithium battery according to another embodiment includes a positive electrode; A cathode and the above-described electrolyte. The shape of the lithium battery is not particularly limited, and includes a lithium secondary battery such as a lithium ion battery, a lithium ion polymer battery, and a lithium sulfur battery, as well as a lithium primary battery.

In the lithium battery, the positive electrode may include a nickel-rich lithium nickel composite oxide having a nickel content of 20 to 90 wt%, for example, 30 to 80 wt% based on the total weight of the transition metal. Such a nickel-rich lithium-nickel composite oxide needs to be improved in high-temperature performance. Addition of the lithium salt and the disulfone compound to the electrolyte improves the charge-discharge characteristics as well as the increase in resistance at high temperatures.

Examples of the lithium nickel complex oxide include compounds represented by the following general formula (8).

[Chemical Formula 8]

Li _a Ni _{1 -b- c} Co _b M ' _c O ₂

0.90? A? 1.8, 0 < b? 0.5, 0? C? 0.2,

M 'is Al, Mn, Cr, Fe, Mg, Sr, V or a combination thereof.

Nickel-rich lithium nickel complex oxide described above, for example, _{LiNi 0 .6 Co 0 .2 Mn 0} .2 O 2 and _{LiNi 0.5 Co 0.2 Mn 0.3 O 2} , or _{LiNi 0 .8 Co 0 .15 Al 0} .05 O There are _two .

For example, in the lithium battery, the negative electrode may include graphite. The lithium battery may have a high voltage of 4.4 V or more, for example, 4.45 V or more.

A lithium battery according to another embodiment includes LiCoO ₂ as a positive electrode.

For example, the lithium battery can 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 agent, a binder and a solvent are mixed is prepared. The positive electrode active material composition is directly coated on the metal current collector to produce a positive electrode plate. Alternatively, the cathode active material composition may be cast on a separate support, and then the film peeled from the support may be laminated on the metal current collector to produce a cathode plate. The anode is not limited to those described above, but may be in a form other than the above.

When the LiCoO ₂ is used as the cathode active material as described above, the lifetime characteristics and direct current internal resistance (DCIR) of the lithium battery and the gas generation amount are reduced, thereby improving battery performance.

The positive electrode active material is also a lithium composite oxide, and any of those conventionally used in the art can be used without limitation. It is also possible to use such a lithium composite oxide together with the nickel-rich lithium-nickel composite oxide described above (LiCoO ₂ was used as a cathode active material).

For example, at least one of complex oxides of metal and lithium selected from cobalt, manganese, nickel, and combinations thereof may be used. Specific examples thereof include Li _a A _1-b B _b D ₂ In the formula, 0.90? A? 1.8, and 0? B? 0.5); Li _a E _{1 - b} B _b O _{2 - c} D _c wherein, in the formula, 0.90? A? 1.8, 0? B? 0.5, 0 _{? C?} 0.05; LiE _{2 - b} B _b O _{4 - c} D _{c where} 0? B? 0.5, 0 _{? C?} 0.05; Li _a Ni _{1 -b- c} Co _b B _c D _? Wherein, in the formula, 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c D _? Wherein, in the formula, 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? 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 (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a CoG _b O ₂ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); Li _a MnG _b O ₂ (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90? A? 1.8, 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} ); _{(0≤f≤2) Li (3-f} ) Fe 2 (PO 4) 3; A compound represented by any one 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, a rare earth element or a combination 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 combinations 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.

Of course, a compound having a coating layer on the surface of the compound may be used, or a compound having a coating layer may be mixed with the compound. The coating layer may comprise an oxide, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a coating element compound of the hydroxycarbonate of the coating element. The compound constituting these coating layers may be amorphous or crystalline. The coating layer may contain Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr or a mixture thereof. The coating layer forming step may be any coating method as long as it can coat the above compound by a method which does not adversely affect the physical properties of the cathode active material (for example, spray coating, dipping, etc.) by using these elements, It will be understood by those skilled in the art that a detailed description will be omitted.

As the conductive agent, carbon black, graphite fine particles, and the like may be used, but not limited thereto, and any conductive agent may be used as long as it can be used in the art.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene and mixtures thereof, and styrene butadiene rubber-based polymers But are not limited thereto and can be used as long as they can be used as binders in the art.

As the solvent, N-methylpyrrolidone, acetone, water or the like may be used, but not limited thereto, and any solvent which can be used in the technical field can be used.

The content of the positive electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery. Depending on the use and configuration of the lithium battery, one or more of the conductive agent, the binder and the solvent may be omitted.

Next, the cathode is prepared.

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

The negative electrode active material may be any material that can be used as a negative electrode active material of a lithium battery in the related art. For example, at least one selected from the group consisting of a lithium metal, a metal capable of alloying with lithium, a transition metal oxide, a non-transition metal oxide, and a carbon-based material.

For example, the metal that can be alloyed with lithium is at least one element selected from the group consisting of Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloys (Y is at least one element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, (Wherein Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, or a combination element thereof, and not a Sn element) ) And the like. The element Y may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, 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.

The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake, spherical or fibrous shape, and the amorphous carbon may be soft carbon or hard carbon carbon, mesophase pitch carbide, calcined coke, and the like.

The conductive agent and the binder in the negative electrode active material composition may be the same as those in the positive electrode active material composition.

The content of the negative electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery. Depending on the use and configuration of the lithium battery, one or more of the conductive agent, the binder and the solvent may be omitted.

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

The separator is usable as long as it is commonly used in a lithium battery. A material having low resistance against the ion movement of the electrolyte and excellent in the ability to impregnate the electrolyte may be used. For example, selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be nonwoven fabric or woven fabric. For example, a rewindable separator such as polyethylene, polypropylene, or the like is used for the lithium ion battery, and a separator having excellent electrolyte impregnation ability can be used for the lithium ion polymer battery. For example, the separator may be produced according to the following method.

A polymer resin, a filler and a solvent are mixed to prepare a separator composition. The separator composition may be coated directly on the electrode and dried to form a separator. Alternatively, after the separator composition is cast and dried on a support, a separator film peeled from the support may be laminated on the electrode to form a separator.

The polymer resin used in the production of the separator is not particularly limited, and any material 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 may be used.

Next, the above-described electrolyte is prepared.

4, the lithium battery 41 includes an anode 43, a cathode 42, and a separator 44. The anode 43, the cathode 42 and the separator 44 described above are wound or folded and housed in the battery case 45. Then, the electrolyte is injected into the battery case 45 and sealed with a cap assembly 46 to complete the lithium battery 41. The battery case may have a cylindrical shape, a rectangular shape, a thin film shape, or the like. For example, the lithium battery may be a large-sized thin-film battery. The lithium battery may be a lithium ion battery.

A separator may be disposed between the anode and the cathode to form a battery structure. The cell structure is laminated in a bi-cell structure, then impregnated with an organic electrolyte solution, and the obtained result is received in a pouch and sealed to complete a lithium ion polymer battery.

In addition, a plurality of battery assemblies may be stacked to form a battery pack, and such battery pack may be used for all devices requiring high capacity and high output. For example, a notebook, a smart phone, an electric vehicle, and the like.

Further, the lithium battery is excellent in life characteristics and high-rate characteristics, and thus can be used in an electric vehicle (EV). For example, 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, an electric bicycle, a power tool, and the like.

As used herein, the term "alkyl group" or "alkylene group" refers to a branched or unbranched aliphatic hydrocarbon group. In one embodiment, the alkyl group may be substituted or unsubstituted. The alkyl group includes alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, But are not necessarily limited thereto, and each of them may be optionally substituted or unsubstituted. In one embodiment, the alkyl group may have from 1 to 6 carbon atoms. For example, the alkyl group having 1 to 6 carbon atoms may be 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. Means, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl.

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

As used herein, the term "alkynyl group" refers to a hydrocarbon group containing from 2 to 20 carbon atoms including at least one carbon-carbon triple bond and includes an ethynyl group, a 1-propynyl group, a 1-butynyl group, 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 from 2 to 40 carbon atoms.

As used herein, the term "aromatic" refers to a ring or ring system having a conjugated pi electron system and includes a carbon ring aromatic (e.g., phenyl) and a heterocyclic aromatic (e.g., pyridine) . The term includes monocyclic rings or fused polycyclic rings (i.e., rings that share adjacent pairs of atoms) if the whole ring system is aromatic.

As used herein, the term "aryl group" means an aromatic ring or ring system (ie, two or more fused rings sharing two adjacent carbon atoms) wherein the ring backbone contains only carbon. If the aryl group is a ring system, then each ring in the system is aromatic. For example, the aryl group includes, but is not limited to, a phenyl group, a biphenyl group, a naphthyl group, a phenanthrenyl group, a naphthacenyl group, 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 multiple fused rings, wherein at least one ring atom is not carbon, i.e., a heteroatom. In the 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, heteroaryl groups include furanyl, thienyl, imidazolyl, quinazolinyl, quinolinyl, isoquinolinyl, quinolinyl, quinolinyl, But are not limited to, quinoxalinyl, pyridinyl, pyrrolyl, oxazolyl, indolyl, and the like.

The term "aralkyl group" and "alkylaryl group" used herein mean an aryl group connected as an substituent group via an alkylene group, such as an aralkyl group having 7 to 14 carbon atoms, Phenylpropyl group, naphthylalkyl group, and the like. In one embodiment, the alkylene group is a lower alkylene group (i.e., an alkylene group having from 1 to 4 carbon atoms).

As used herein, a "cycloalkenyl group" is a carbocycle ring or ring system having one or more double bonds, which is an aromatic ring-free ring system. For example, a cyclohexenyl group.

As used herein, a "heterocyclyl group" is a non-aromatic ring or ring system comprising at least one heteroatom in the ring skeleton.

As used herein, "halogen" 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 replacing one or more hydrogen atoms with other atoms or functional groups in a non-substituted mother group. Unless otherwise stated, when a functional group is considered "substituted ", it is meant that the functional group 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, An alkenyl group, an alkyl group having 1 to 40 carbon atoms, and an aryl group having 7 to 40 carbon atoms. When a functional group is described as "optionally substituted ", it is meant that the functional group may be substituted with the substituent described above.

The present invention will be described in more detail by way of the following examples and comparative examples. However, the examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Manufacturing example  1: Synthesis of compound of formula (4)

The compound of formula (4) was prepared according to the following procedure.

[Reaction Scheme 1]

The reaction mixture was added dropwise to ethylene chlorophosphite (Alfa Aesar; 20.24 g, 0.16 mol) under nitrogen atmosphere while dropping antimony (III) trifluoride (Alfa Aesar; 14.30 g, 0.08 mol) Lt; / RTI &gt;

Antimony trifluoride was added to the reaction mixture and stirred for about 30 minutes until the reaction mixture reached room temperature (25 &lt; 0 &gt; C). The reaction mixture was heat treated at about 55 캜 and held at this temperature for 2 hours. The reaction mixture was then cooled again to room temperature (25 &lt; 0 &gt; C) to give a crude product.

The crude product was distilled under vacuum (about 150 Torr) to remove impurities and to collect materials with boiling points of about 44-45 [deg.] C. The resultant was distilled again under vacuum (about 150 Torr) to remove impurities and 43-44.5 ^{o The} substance having the boiling point of C was collected to obtain a compound represented by the general formula (4).

[Chemical Formula 4]

¹ H (400 MHz; CDCl ₃ ; 25 ^{o C): δ 4.26-4.09 (m} , 4H)

¹⁹ F (400 MHz; CDCl ₃ ; 25 ^{o C): δ -41.12 (d} , J PF = 1229.7 Hz)

_{^{31 P (400 MHz; CDCl 3}} ; 25 ^{o C): δ 124.28 (d} , J PF = 1231.1 Hz)

Example  1: Preparation of electrolyte

To a mixed solvent of 3: 5: 2 by volume of a mixture of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl propionate (EP), a compound represented by the formula 4 obtained in Preparation Example 1 and 0.90 M LiPF ₆ To prepare a dissolved electrolyte. The content of the compound represented by the general formula (4) was 0.1% by weight based on the total weight of the electrolyte.

Example  2: Preparation of electrolyte

The procedure of Example 1 was repeated except that the content of the compound represented by the general formula (4) was changed to 0.25% by weight.

Comparative Example  1: Preparation of electrolyte

Was carried out in the same manner as in Example 1, except that the compound represented by the general formula (4) was not added.

Example  3: Manufacture of lithium battery

, 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 carboxymethylcellulose (CMC, NIPPON A & And the mixture was stirred for 60 minutes using a mechanical stirrer to prepare an anode active material slurry. The slurry was coated on a copper collector having a thickness of 10 mu m to a thickness of about 60 mu m using a doctor blade, dried in a hot air drier at 100 DEG C for 0.5 hour, dried again under vacuum at 120 DEG C for 4 hours, (roll press) to produce a negative electrode.

(BM-720H, Zeon Corporation) 0.25 wt.%, Poly (vinylidene fluoride), polyvinylidene fluoride (LiCoO ₂₎ 97.45 wt.% As a conductive agent, 0.5 wt.% Of artificial graphite (SFG 6, Timcal) powder, 0.7 wt.% Of carbon black 0.9% by weight of vinylidene fluoride (PVdF, S6020, Solvay) and 0.2% by weight of polyvinylidene fluoride (PVdF, S5130, Solvay) were added to a solvent of N-methyl-2-pyrrolidone, And the mixture was stirred for 30 minutes to prepare a cathode active material slurry.

The slurry was coated on an aluminum current collector having a thickness of about 60 mu m with a doctor blade to a thickness of about 60 mu m and dried in a hot air drier at 100 DEG C for 0.5 hour and then dried again under vacuum at 120 DEG C for 4 hours, (roll press) to prepare a positive electrode.

A 14 占 퐉 thick polyethylene separator coated with a ceramic on the anode side as a separator and an electrolyte prepared according to Example 1 as an electrolyte were used to produce a lithium battery.

Example  4: Manufacture of lithium battery

A lithium battery was produced in the same manner as in Preparation Example 1, except that the electrolyte prepared in Example 2 was used instead of the electrolyte prepared in Example 1, respectively.

Example  5-7: Preparation of electrolyte and lithium battery

Except that the compound of the formula (5), the compound of the formula (6) and the compound of the formula (7) were used instead of the compound of the formula (4), respectively. A lithium battery was prepared in the same manner as in Example 3 except that the electrolyte obtained in the above procedure was used in place of the electrolyte of Example 1.

Example  8: Preparation of electrolyte

The procedure of Example 1 was repeated except that the content of the compound represented by the general formula (4) was changed to 0.5 wt%.

Example  9: Manufacture of lithium battery

A lithium battery was produced in the same manner as in Production Example 1, except that the electrolyte prepared in Example 8 was used instead of the electrolyte prepared in Example 1, respectively.

Comparative Example  2: Manufacture of lithium battery

A lithium battery was produced in the same manner as in Example 3, except that the electrolyte prepared in Comparative Example 1 was used in place of the electrolyte prepared in Example 1.

Evaluation example  1: Life

1) Examples 3-4 and Comparative Example 2

The lithium battery prepared in Example 3-4 and Comparative Example 2 was charged at a constant current of 45 ° C at a current of 0.1 C rate until the voltage reached 4.30 V (vs. Li), and then 4.30 V in constant voltage mode And cut off at a current of 0.05 C rate. Then, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during the discharge (Mars phase, 1 ^st cycle).

The lithium battery having passed through the 1 ^st cycle of the above-described chemical conversion step was charged at a constant current of 0.2 C at a current of 45 C until the voltage reached 4.40 V (vs. Li), then maintained at 4.40 V in a constant voltage mode, Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt; Subsequently, discharge was performed at a constant current of 0.2 C rate until the voltage reached 2.8 V (vs. Li) (Mars phase, 2nd cycle).

The lithium battery having undergone the above conversion step was subjected to constant current charging at a current of 1.0 C rate at 45 DEG C until the voltage reached 4.40 V (vs. Li), and then, at a constant current of 4.40 V in a constant voltage mode, (cut-off). The cycle of discharging at a constant current of 1.0 C rate until the voltage reached 2.75 V (vs. Li) at discharge was repeated up to 150 ^th cycle.

In all the above charge / discharge cycles, there was a stop time of 20 minutes after one charge / discharge cycle. The change in non-discharge capacity according to the number of cycles, which is a part of the results of the charge-discharge experiments, is shown in FIG.

As shown in FIG. 1, the lithium batteries according to Examples 3 and 4 were similar in lifetime characteristics to those of the lithium battery according to Comparative Example 2.

2) Examples 3-7 and 9 and Comparative Example 2

The lithium batteries produced in Examples 3-7 and 9 and Comparative Example 2 were subjected to constant current charging at a current of 0.1 C rate at 45 DEG C until the voltage reached 4.45 V (vs. Li), and then 4.45 Lt; RTI ID = 0.0 &gt; 0.05 C &lt; / RTI &gt; Then, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during the discharge (Mars phase, 1 ^st cycle).

The lithium battery having passed through the 1 ^st cycle of the above-described chemical conversion step was charged at a constant current of 0.2 C at a current of 45 C until the voltage reached 4.45 V (vs. Li), then maintained at 4.45 V in a constant voltage mode, Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt; Subsequently, discharge was performed at a constant current of 0.2 C rate until the voltage reached 2.8 V (vs. Li) (Mars phase, 2nd cycle).

The above lithium cell was subjected to constant current charging at a current of 1.0 C rate at 45 캜 until the voltage reached 4.45 V (vs. Li), and then, at a constant current of 4.45 V in a constant voltage mode, (cut-off). The cycle of discharging at a constant current of 1.0 C rate until the voltage reached 2.75 V (vs. Li) at discharge was repeated up to 150 ^th cycle.

In all the above charge / discharge cycles, there was a stop time of 20 minutes after one charge / discharge cycle.

FIG. 2 shows changes in the non-discharge capacity according to the number of cycles, which is a part of the results of the charge-discharge experiments.

As shown in FIG. 2, the lithium batteries according to Examples 3, 4,

Life characteristics at a high voltage of 4.45 V were improved as compared with a lithium battery. The discharge capacity characteristics of the lithium batteries produced in Examples 5 to 7 were also evaluated. As a result of the evaluation, the lithium batteries prepared according to Examples 5 to 7 exhibited almost the same level as the lithium batteries prepared according to Examples 3, 4 and 9.

The capacity retention rates of the lithium batteries prepared in Examples 3, 4 and 9 and Comparative Example 2 were evaluated. The evaluation result is as shown in Fig.

The capacity retention rate is defined by the following equation (1).

<Formula 1>

Capacity retention rate = [discharge capacity in 150 ^th cycle / discharge capacity in 1 ^st cycle] × 100

As a result of the evaluation, it was found that the lithium battery produced according to Examples 3, 4 and 9 has improved life characteristics at a high voltage of 4.45 V as compared with the lithium battery of Comparative Example 2. [

The lithium battery produced according to Examples 5 to 7 exhibited life characteristics equivalent to those of the lithium battery of Example 3 described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. It will be apparent to those skilled in the art that various modifications and variations are possible in light of the above teachings will be. Accordingly, the scope of protection of the present invention should be determined by the appended claims.

41: Lithium battery 42: cathode
43: anode 44: separator
45: Battery case 46: Cap assembly

Claims (11)

A compound represented by Formula 1 below; Lithium salts; And an electrolyte for a lithium battery comprising an organic solvent:
&Lt; Formula 1 >

Wherein X is a halogen atom,
R ₁ and R ₂ A substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C1-C20 alkyl group, A substituted C2-C20 heteroaryl group, and R ₁ and R ₂ may be connected to each other to form a ring. The method according to claim 1,
Wherein the compound represented by Formula 1 is a compound represented by Formula 1a:
<Formula 1a>

In formula (1), R ₁ and R ₂ A substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C1-C20 alkyl group, A substituted C2-C20 heteroaryl group,
R ¹ and R ² may be connected to each other to form a ring. The method according to claim 1,
Wherein R ₁ and R ₂ are connected to each other to form a substituted or unsubstituted C 2 to C 5 alkylene group. The method according to claim 1,
The said R ₁ and R ₂ are connected to each other _{-CH 2 -CH 2 -, -CH 2} -C (CH 3) 2 -CH 2 - or _{-C (CH 3) 2 -C (} CH 3) 2 - group forming An electrolyte for a lithium battery. The method according to claim 1,
The compound represented by the formula (1) is a compound represented by the following formula:
(2)

In Formula 2, R ₃ To R ₆ independently represent hydrogen, a C1-C10 alkyl group, a C6-C20 aryl group, a halogen atom, a cyano group, a hydroxyl group, a C2-C20 heteroaryl group, a C6- Lt; RTI ID = 0.0 &gt; C20 &lt; / RTI &gt; heterocyclic group,
(3)

In the above formula (3), R ₇ To R ₁₂ independently represent hydrogen, a C 1 -C 10 alkyl group, a C 6 -C 20 aryl group, a halogen atom, a cyano group, a hydroxyl group, a C 2 -C 20 heteroaryl group, a C 6 -C 20 carbon ring group, Lt; RTI ID = 0.0 &gt; C20 &lt; / RTI &gt; The method according to claim 1,
Wherein the compound is at least one selected from the group consisting of a compound represented by the following formula (4), a compound represented by the formula (5), a compound represented by the formula (6) and a compound represented by the formula (7).
[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

The method according to claim 1,
Wherein the content of the compound represented by Formula 1 is 0.01 to 10% by weight based on the total weight of the electrolyte. The method according to claim 1,
Wherein the content of the lithium salt is 0.5 to 3% by weight based on the total weight of the electrolyte. The method according to claim 1,
Wherein the organic solvent is at least one 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. The method according to claim 1,
Wherein the organic solvent is selected from the group consisting of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate (PC), ethylene carbonate But are not limited to, ethylene carbonate (FEC), butylene carbonate, ethyl propionate, ethyl butyrate, acetonitrile, succinonitrile (SN), dimethylsulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, Wherein the electrolyte comprises at least one selected from the group consisting of lactone and tetrahydrofuran. anode;
cathode; And
A lithium battery comprising the electrolyte according to any one of claims 1 to 10.

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