KR20170101792A - Electrolyte for lithium battery and Lithium battery including the same - Google Patents

Abstract

Proposed are an electrolyte for a lithium battery comprising a compound represented by chemical formula 1, and a lithium battery comprising the same. In the chemical formula 1, n is 0 or 1, wherein i) when n is 0, R_2 is a substituted or unsubstituted alkenyl group having 2-10 carbon atoms, and R_1 is a substituted or unsubstituted alkyl group having 1-5 carbon atoms, a substituted or unsubstituted aryl group having 6-10 carbon atoms, or a substituted or unsubstituted heteroaryl group having 3-20 carbon atoms, and ii) when n is 1, R_1 to R_4 are each independently a substituted or unsubstituted alkyl group having 1-5 carbon atoms, a substituted or unsubstituted aryl group having 6-10 carbon atoms, or a substituted or unsubstituted heteroaryl group having 3-20 carbon atoms.

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 same.

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 has been proposed to improve the lifetime of a lithium battery using a sulfone compound as an additive for the electrolyte. However, when such an additive is used, the lifetime at a high temperature and a high voltage can not reach a satisfactory level and there is a lot of room for improvement.

One aspect is to provide an electrolyte for a lithium battery improved in lifetime characteristics at a high temperature and a lithium battery employing the same.

According to one aspect,

There is provided an electrolyte for a lithium battery comprising a compound represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, n is 0 or 1,

i) when n is 0, R ₂ is a substituted or unsubstituted C2-C10 alkenyl group,

R ₁ is a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C6-C10 aryl group or a substituted or unsubstituted C3-C20 heteroaryl group,

ii) when n is 1, R ₁ to R ₄ independently of one another are a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C6-C10 aryl group or a substituted or unsubstituted C3- To 20 heteroaryl groups.

Anodic according to another aspect; There is provided a lithium battery comprising a negative electrode and at least one selected from the above-described electrolytes and reaction products thereof.

By using the electrolyte for a lithium battery according to one aspect, it is possible to manufacture a lithium battery with improved lifetime at high temperature and room temperature and suppressed increase in cell resistance.

1 is a schematic diagram of a lithium battery according to an exemplary embodiment.
2A is a graph showing lifetime characteristics in a lithium battery manufactured according to Production Examples 1, 3 and 4 and Comparative Production Example 1. FIG.
FIG. 2B is a graph showing lifetime characteristics in a lithium battery manufactured according to Production Examples 2, 5 and 6 and Comparative Production Example 1. FIG.
FIGS. 3 to 5 show the results of cyclolactametry analysis using the electrolytes prepared in Examples 1-2 and Comparative Examples 1, respectively.

Hereinafter, an electrolyte for a lithium battery and a lithium battery including the same according to exemplary embodiments 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).

[Chemical Formula 1]

In Formula 1, n is 0 or 1,

i) when n is 0, R ₂ is a substituted or unsubstituted C2-C10 alkenyl group,

R ₁ is a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C6-C10 aryl group or a substituted or unsubstituted C3-C20 heteroaryl group,

ii) when n is 1, R ₁ to R ₄ independently of one another are a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C6-C10 aryl group or a substituted or unsubstituted C3- To 20 heteroaryl groups.

In the above formula (1), when n is 0, R ₂ is, for example, a substituted or unsubstituted C2-C10 alkenyl group. Examples of the alkenyl group include a vinyl group and an allyl group.

The compound represented by Formula 1 has an isocyanate (-N = C = O) group. This isocyanate functional group has high chemical reactivity to the components (e.g., lithium alkoxide) present in the SEI layer of the negative electrode or to the hydroxy (-OH) group present on the carbon-based or silicon negative electrode surface. Thus, the addition of the compound of formula 1 to the electrolyte serves to stabilize the SEI layer at high temperatures (e.g., about 45 DEG C) by inhibiting other side reactions. The isocyanate group possessed by the compound of formula (1) can form a donor-acceptor bond with the transition metal oxide of the cathode active material to form a protective layer in the form of a complex. Therefore, when the compound of Formula 1 is present on the surface of the electrode during the initial charging process of the lithium battery, a more stable and inert layer is formed on the surface of the electrode, and the inert layer forms a strong bond with the electrode active material surface. Even when such an inactive layer is repeatedly charged and discharged, it can be maintained continuously on the surface of the electrode, and the stability of the lithium battery can be improved.

The compound represented by the formula (1) is, for example, a compound represented by the following formula (2).

(2)

In Formula 2, R ₁ is, for example, a C1-C5 alkyl group.

According to another embodiment, the compound represented by the formula (1) is a compound represented by the following formula (3) or (4).

 (3)

[Chemical Formula 4]

Substituent group which may be substituted with an aryl group an alkyl group, an alkenyl group, an aryl group, and heteroaryl in formula (I), for example an alkyl group of a halogen atom, halogen-substituted C1-C20 (for example: CCF _3, CHCF _2, CH ₂ F, CCl ₃ or the like), C1-C20 alkoxy, C2-C20 alkoxyalkyl, hydroxy, nitro, cyano, amino, amidino, hydrazine, hydrazone, carboxyl group or salt thereof, sulfonyl group, sulfamoyl group C2-C20 alkynyl group, C1-C20 heteroalkyl group, C6-C20 aryl group, C6-C20 arylalkyl group, C6-C20 arylalkyl group, , A C6-C20 heteroaryl group, a C7-C20 heteroarylalkyl group, a C6-C20 heteroaryloxy group, a C6-C20 heteroaryloxyalkyl group or a C6-C20 heteroarylalkyl group.

According to one embodiment, the amount of the compound represented by Formula 1 is 0.001 to 10% by weight, for example, 0.005 to 5% by weight, and more preferably 0.05 to 0.2% by weight based on the total weight of the electrolyte. When the content of the compound of the formula (1) in the electrolyte is within the above range, it is possible to obtain a battery having improved life characteristics and high temperature charging / discharging characteristics.

The electrolyte according to one embodiment is excellent in normal temperature (25 캜) and high temperature lifetime characteristics at a high voltage of 4.2 V or more in operating voltage.

According to another embodiment, A negative electrode, and a lithium battery comprising at least one selected from the above-described electrolytes and reaction products thereof.

The term " reaction product " means that when the electrolyte has an unsaturated bond such as a carbon-carbon double bond as in the case of the compound represented by the formula (3), when the reaction between the unsaturated bonds (for example, polymerization reaction) Means a reaction product. Or the term " reaction product " means a reaction product of a decomposition product of an electrolyte, an electrode or an SEI layer, a compound represented by formula (I) or other component (s) of an electrolyte after a cell operation, 1 and the reaction product of the other component (s) in the electrolyte or the battery, and the like.

The positive electrode includes a nickel-based complex compound having a nickel content of 50 to 100 mol% based on the total amount of transition metals. And the content of nickel is 50 mol% to 100 mol%, the lithium nickel composite compound is a compound represented by the following formula (6).

[Chemical Formula 6]

Li _x Ni _y M _{1 - y} O ₂

In Formula 6, x is 0.9 to 1.2, y is 0.5 to 1.0, and M is at least one selected from cobalt (Co), manganese (Mn), and aluminum (Al).

The compound of formula (6) is, for example, a compound represented by the following formula (7) or a compound represented by the following formula (8).

(7)

Li _x Ni _y Co _z Mn _{1 - y - z} O ₂

1? 0? Z? 0.5, 0? 1-y-z? 0.5,

 [Chemical Formula 8]

Li _x Ni _y Co _z Al _{1 - y - z} O ₂

In the formula (8), 0.5? Y?? 1, 0? Z?

According to one embodiment, the compound represented by the formula (7) and the compound represented by the formula (8) can be used together as the cathode active material. When the compound of the formula (7) and the compound of the formula (8) are used together, the initial capacity of the lithium secondary battery is improved.

When the compound represented by the general formula (7) and the compound represented by the general formula (8) are used together, the content of the compound represented by the general formula (7) is preferably 100 parts by weight or more based on 100 parts by weight of the total amount of the compound 30 to 80 parts by weight.

In the lithium battery, the positive electrode is a nickel-rich nickel-based composite oxide having a nickel content of, for example, 50 mol% to 100 mol%, specifically, 80 to 100 mol%. When the content of nickel is within the above range, there is an advantage that a lithium battery having a high output and a high capacity can be produced. However, when the nickel content is high, the dissolution of the transition metal in the nickel-rich lithium-nickel composite oxide is intensified, thereby deteriorating the high-temperature characteristics. However, by using an electrolyte according to one embodiment, the transition metal elution itself in the anode can be reduced. Also, because of the effect of the polymer coating on the anode, the anode loss due to the side reactants can be reduced. As described above, the lithium battery having a high output and a high capacity can be manufactured while having the above-mentioned high temperature characteristic is prevented from being deteriorated by being included in the electrolyte, and thus the lifetime and the resistance increase suppressing effect at high temperature are excellent. When the content of nickel is within the above range, the effect of suppressing increase in lifetime and resistance at high temperatures of the lithium battery is remarkably exhibited.

When the nickel-rich lithium-nickel-based composite oxide and the electrolyte are used together, the lifetime at a high temperature of the lithium battery and the effect of suppressing increase in resistance of the battery are excellent.

The compounds of the formula (6) is LiNi _{0. 6} Co _{0 . 2} Mn _{0 . 2} O ₂ , or LiNi _{0 . 88} Co _{0 . 1} Al _{0 . 02} < / _RTI > According to one embodiment, LiNi _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ and LiNi _{0 . 88} Co _{0 . 1} Al _{0 . 02} O ₂ at a mixing ratio by weight of 7: 3, 6: 4, or 8: 2.

In the electrolyte, the organic solvent may include a low boiling point 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 ethers, and cyclic ethers .

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 ), Butylene carbonate, ethyl propionate, ethyl butyrate, acetonitrile, succinonitrile (SN), dimethylsulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, gamma-butyrolactone, Furan, and the like, but it is not necessarily limited to these, and any low boiling point solvent that can be used in the technical field is possible.

The concentration of the lithium salt in the electrolyte may be 0.01 to 2.0 M. However, the concentration 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 lithium salt used in the electrolyte is not particularly limited and can be used as a lithium salt in the art. 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 and y are 1 to 20), LiCl, LiI or mixtures thereof. For example, the lithium salt in the electrolyte can be LiPF _6.

The electrolyte may be in a liquid or gel state.

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, graphite or a silicon-carbon composite / graphite may be used as an anode active material. The lithium battery may have a high voltage of 4.5 V or more, for example, 4.8 V or more.

The lithium battery according to one embodiment 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 a film peeled from the support may be laminated on the metal current collector to produce a cathode. The anode is not limited to those described above, but may be in a form other than the above.

The cathode active material may be a lithium-containing metal oxide as well as the nickel-rich lithium-nickel composite oxide described above. As the lithium-containing metal oxide, 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 , wherein 0.90? a? 1.8, and 0? b? 0.5; Li _a E _{1 - b} B _b O _{2 - c} D _{c where} 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, 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-α F ₂ wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2; 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, 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 ₂ 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 wherein, in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1; Li _a MnG _b O ₂ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ wherein, in the above formula, 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); In the formula of LiFePO ₄ may be used a compound represented by any one:

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.

For example, LiCoO ₂ , LiMn _x O _2x (x = 1 or 2), LiNi _{1 - x} Mn _x O _2x (0 <x <1), LiNi _{1 -xy} Co _x Mn _y O ₂ 0.5, 0≤y≤0.5, a 1-xy> 0.5), LiFePO 4 or the like.

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 that does not adversely affect 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 lithium-alloyable metal may be at least one selected from the group consisting of Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloys (Y is an alkali metal, an alkaline earth metal, a Group 13 element, A rare earth element or a combination element thereof and not Si, an Sn-Y alloy (Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, Or 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 the form of amorphous, plate-like, flake, spherical or fibrous type, 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.

As shown in FIG. 1, the lithium battery 1 includes an anode 3, a cathode 2, and a separator 4. The anode 3, the cathode 2 and the separator 4 described above are wound or folded and housed in the battery case 5. Then, 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 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 electrolyte, 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, alkyl refers to fully saturated branched or unbranched (or straight chain or linear) hydrocarbons.

Non-limiting examples of "alkyl" include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n- pentyl, isopentyl, neopentyl, isoamyl, -Methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl and the like.

"Alkyl" at least one hydrogen atom of an alkyl group of a halogen atom, halogen-substituted C1-C20 (for _{example: CCF 3, CHCF 2, CH} 2 F, CCl 3 , etc.), an alkoxy of C1-C20 alkoxy, C2-C20 of A sulfamoyl group, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1-C20 alkyl group, a hydroxyl group, a nitro group, a cyano group, an amino group, an amidino group, a hydrazine, a hydrazone, C20 alkenyl, C2-C20 alkynyl, C1-C20 heteroalkyl, C6-C20 aryl, C6-C20 arylalkyl, C6-C20 heteroaryl, C7-C20 heteroaryl An alkyl group, a C6-C20 heteroaryloxy group, a C6-C20 heteroaryloxyalkyl group or a C6-C20 heteroarylalkyl group.

The term &quot; halogen &quot; includes fluorine, bromine, chlorine, iodine and the like.

&Quot; Aryl &quot; also includes a group in which the aromatic ring is fused to one or more carbon ring rings. Non-limiting examples of &quot; aryl &quot; include phenyl, naphthyl, tetrahydronaphthyl, and the like.

Also, at least one hydrogen atom in the &quot; aryl &quot; group may be substituted with the same substituent as in the case of the above-mentioned alkyl group.

&Quot; Heteroaryl &quot; means monocyclic or bicyclic organic compounds containing one or more heteroatoms selected from N, O, P, or S and the remaining ring atoms carbon. The heteroaryl group may contain, for example, from 1 to 5 hetero atoms, and may include 5-10 ring members. The S or N may be oxidized to have various oxidation states.

Examples of heteroaryl include thienyl, furyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, , 5-oxadiazolyl, 1,3,4-oxadiazolyl group, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, Thiadiazolyl, isothiazol-3-yl, isothiazol-4-yl, isothiazol-5-yl, oxazol- Yl, isoxazol-3-yl, 1,2,4-triazol-5-yl, Yl, pyrid-3-yl, 2-pyrazin-4-yl, 1,2,3-triazol-5-yl, tetrazolyl, 2-yl, pyrazin-4-yl, pyrazin-5-yl, 2-pyrimidin-2-yl, 4-pyrimidin-2-yl or 5-pyrimidin-2-yl.

The term &quot; heteroaryl &quot; includes those where the heteroaromatic ring is fused to one or more aryl, cycloaliphatic, or heterocycle.

The electrolyte and the lithium battery will be described in more detail with reference to the following examples and comparative examples, but the following examples are not intended to limit the electrolyte and the lithium battery.

Example  1: Preparation of electrolyte

First, 0.05% by weight of a compound represented by the general formula (3) was added to a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) at a ratio of 2: 1: 7 by volume, and LiPF ₆ In addition, LiPF ₆ was dissolved to a concentration of 1.5 M to prepare an electrolyte.

(3)

Example  2: Preparation of electrolyte

An electrolyte was prepared in the same manner as in Example 1 except that the compound represented by Chemical Formula 4 was added instead of the compound represented by Chemical Formula 3.

[Chemical Formula 4]

Example  3-4: Preparation of electrolyte

The electrolyte was prepared in the same manner as in Example 1 except that the content of the compound of the formula (3) was changed to 0.1% by weight and 0.2% by weight in the production of the electrolyte, respectively.

Example  5-6: Preparation of electrolyte

An electrolyte was prepared in the same manner as in Example 2 except that the content of the compound of the following formula (4) was changed to 0.1 wt% and 0.2 wt%, respectively, during the production of the electrolyte.

Comparative Example  1: Preparation of electrolyte

An electrolyte was prepared in the same manner as in Example 1, except that the compound represented by the general formula (3) was not added.

Production Example 1: Lithium-ion battery  Produce

The negative electrode was prepared according to the following procedure.

, 97% by weight of a silicon-carbon nanocomposite (SCN) and 89% by weight of graphite), 1.5% by weight of a conductive agent (BM408 of Daicel) as a binder BM400-B) was added to distilled water, 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. The mixing density (E / D) of the cathode was 1.55 g / cc and the loading level (L / L) was 14.36 mg / cm ² .

Separately, the positive electrode was prepared by the following procedure.

7: 3 ratio by weight of LiNi _{0. 6} Co _{0 . 2} Mn _{0 . 2} O ₂ (NCM 622, Samsung SDI) and LiNi _{0 . 88} Co _{0 . 1} Al _{0 . 02} mixture of O ₂ (PVDF, Solef 6020, manufactured by Solvay) 3.0 weight% as a conductive agent (Denka black) and 94 weight% of a binder were mixed in a solvent of N-methyl-2-pyrrolidone and then mixed using a mechanical stirrer 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. The mixing density (E / D) of the anode is 3.15 g / cc and the loading level (L / L) is 27.05 mg / cm ² .

A lithium battery (2016 full battery) was produced using the electrolyte of Example 1 as a separator (polyethylene separator (thickness: 16 mu m) SK Innovation) and an electrolyte.

Production Example  2-6

A lithium battery was produced in the same manner as in Production Example 1 except that the electrolyte of Example 2-6 was used instead of the electrolyte of Example 1, respectively.

Comparative Production Example  1: Manufacture of lithium battery

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

Evaluation example  1: High voltage (4.2V), high temperature (45 ℃) Charging and discharging  characteristic

1) Production Examples 1 and 3.4 and Comparative Production Example 1

The lithium batteries produced in Production Examples 1, 3 and 4 and Comparative Production Example 1 were mixed at 45 ° C and 0.2C

rate current until the voltage reached 4.20 V (vs. Li) and then cut off at a current of 0.05 C rate while maintaining 4.20 V in constant voltage mode. Then, at the time of discharging, the battery was discharged at a constant current of 0.2 C rate until the voltage reached 2.5 V (vs. Li) (Mars phase, 1 ^st cycle).

The lithium battery having passed through the 1 ^st cycle of the above conversion step was charged with a constant current until the voltage reached 4.20 V (vs. Li) at a current of 0.2 C rate at 45 ° C and then maintained at 4. 0 V in a constant voltage mode, Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt; Then, at the time of discharge, discharge was performed at a constant current of 0.2 C rate until the voltage reached 2.5 V (vs. Li) (Mars phase, 2 ^nd cycle).

The lithium battery having undergone the above conversion step was charged at a constant current of 45 ° C. at a current of 1.6 C rate until the voltage reached 4.20 V (vs. Li), and then maintained at 4.20 V in a constant voltage mode, (cut-off). The cycle of discharging at a constant current of 1.6 C rate until the voltage reached 2.0 V (vs. Li) at discharge was repeated up to 100 ^th cycle.

A stopping time of 10 minutes was provided after one charge / discharge cycle in all of the above charge / discharge cycles.

Some of the results of the charge-discharge experiments are shown in Fig.

Referring to FIG. 2, it was confirmed that the lithium battery of Production Examples 1, 3, and 4 improved the high temperature lifetime characteristics as compared with Comparative Production Example 1.

Meanwhile, the charging / discharging characteristics at 45 ° C of the lithium battery manufactured according to Production Examples 2 and 5-6 were evaluated in the same manner as in the method for evaluating the high temperature charging / discharging characteristics of the lithium battery manufactured in Production Example 1 described above. The evaluation results of the high-temperature charge-discharge characteristics are shown in Fig. 2B.

As a result of evaluation, the lithium battery manufactured according to Production Examples 2, 5, and 6 exhibited similar high-temperature charge-discharge characteristics to those of Production Example 6 lithium battery.

Evaluation example  2: Electrochemical stability (anode LSV )

The electrochemical stability measurements of the electrolytes prepared in Example 1 and Comparative Example 1 were evaluated according to the following methods. First, a platinum electrode is used as a working electrode (WE), a lithium metal is used as a counter electrode (CE), and a lithium metal is used as a reference electrode (RE) The electrolyte membrane prepared in Example 1 and Comparative Example 1 was inserted into a three-electrode system battery. The electrochemical stability was measured by Linear Sweep Voltammetry (LSV) up to 6V at a scan rate of 5mV / s.

As a result of the electrochemical stability evaluation, the electrolyte of Example 1 did not show any reduction decomposition as compared with Comparative Example 1. From this, it was found that the stability of the oxidative decomposition was excellent in the anode and the reduction. As a result, it was confirmed that the compound represented by the general formula (3) was a stable electrolyte additive at the anode.

Evaluation example  3: Electrochemical stability (cathode CV )

The electrochemical stability measurements of the electrolytes prepared in Examples 1-2 and Comparative Example 1 were evaluated according to the following methods. Cathode To evaluate the CV, graphite was used as a working electrode (WE), lithium metal was used as a counter electrode (CE), lithium metal was used as a reference electrode (RE) The electrolyte membrane prepared in Example 1 and Comparative Example 1 was inserted into a three-electrode system battery. The electrochemical stability was measured by CV up to 3V-0V with a scan rate of 1mV / s. The results of the electrochemical stability evaluation are shown in FIG. 3 to FIG. FIGS. 3 to 5 show results of cathode CV analysis using the electrolyte prepared according to Example 1, Example 2, and Comparative Example 1, respectively.

As a result of the measurement, the electrolyte of Comparative Example 1 observed the ethylene carbonate reduction peak in the 0.5 V region in the first cycle, and the secondary and tertiary cycles after the first cycle (for example, the third and fifth cycles) A current reduction was observed. Compared to this

As compared with the case of Comparative Example 1, no reduction decomposition was observed using the electrolytes of Examples 1 and 2. From this, it was confirmed that the compound represented by the formula (3) and the compound represented by the formula (4) were stable electrolyte additives in the negative electrode.

1: Lithium battery 2: cathode
3: anode 4: separator
5: Battery case 6: Cap assembly

Claims (12)

1. An electrolyte for a lithium battery comprising a compound represented by the following Formula 1:
[Chemical Formula 1]

In Formula 1, n is 0 or 1,
i) when n is 0, R ₂ is a substituted or unsubstituted C2-C10 alkenyl group,
R ₁ is a substituted or unsubstituted C ₁ -C 5 alkyl group, a substituted or unsubstituted
Is an unsubstituted C6-C10 aryl group or a substituted or unsubstituted C3-C20 heteroaryl group,
ii) when n is 1, R ₁ to R ₄ independently of one another are a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C6-C10 aryl group or a substituted or unsubstituted C3- To 20 heteroaryl groups. The method according to claim 1,
Wherein the compound represented by Formula 1 is a compound represented by Formula 2:
(2)

In the formula (2), R ₁ is a C ₁ -C 5 alkyl group. The method according to claim 1,
Wherein the compound represented by the formula (1) is a compound represented by the following formula (3) or (4):
(3)

[Chemical Formula 4]

The method according to claim 1,
The content of the compound represented by the formula (1) is 0.001 to 10% by weight based on the total weight of the electrolyte. The method according to claim 1,
The content of the compound represented by Formula 1 is 0.05 to 0.2 wt% based on the total weight of the electrolyte. The method according to claim 1,
The electrolyte further comprises an organic solvent,
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 ethers, and cyclic ethers. The method according to claim 1,
Wherein the electrolyte further comprises a lithium salt,
The lithium salt may be at least one selected from the group consisting of 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 , ₂ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (x and y are 1 to 20), LiCl, LiI or a mixture thereof. A lithium battery comprising at least one selected from an anode, a cathode, and an electrolyte according to any one of claims 1 to 7 and a reaction product thereof. 9. The method of claim 8,
Wherein the positive electrode comprises a lithium-nickel complex compound having a nickel content of 50 to 100 mol% based on the total weight of the transition metal. 10. The method of claim 9,
Wherein the lithium nickel composite compound having a nickel content of 50 mol% to 100 mol% is a lithium compound,
(6)
Li _x Ni _y M _{1 - y} O ₂
In Formula 6, x is 0.9 to 1.2, y is 0.5 to 1.0, and M is at least one selected from cobalt (Co), manganese (Mn), and aluminum (Al). 11. The method of claim 10,
Wherein the compound of Formula 6 is a compound represented by Formula 7 or a compound represented by Formula 8,
(7)
Li _x Ni _y Co _z Mn _{1 - y - z} O ₂
In the formula (7), 1? X? 1.2, 0.5? Y <1, 0? Z? 0.5, 0? 1-yz?
[Chemical Formula 8]
Li _x Ni _y Co _z Al _{1 - y - z} O ₂
In the formula (8), 0.5? Y?? 1, 0? Z? 11. The method of claim 10,
The compounds of the formula (6) is LiNi _{0. 6} Co _{0 . 2} Mn _{0 . 2} O ₂ , LiNi _{0 . 88} Co _{0 . 1} Al _{0 . 02} O ₂ or a mixture thereof.

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