WO2016208946A1 - Electrolyte for lithium secondary battery and lithium secondary battery comprising same - Google Patents

Electrolyte for lithium secondary battery and lithium secondary battery comprising same Download PDF

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Publication number
WO2016208946A1
WO2016208946A1 PCT/KR2016/006587 KR2016006587W WO2016208946A1 WO 2016208946 A1 WO2016208946 A1 WO 2016208946A1 KR 2016006587 W KR2016006587 W KR 2016006587W WO 2016208946 A1 WO2016208946 A1 WO 2016208946A1
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WIPO (PCT)
Prior art keywords
electrolyte
secondary battery
lithium secondary
dinitrile
perfluoro
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PCT/KR2016/006587
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French (fr)
Korean (ko)
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정명훈
이종현
정승훈
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솔브레인 주식회사
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Application filed by 솔브레인 주식회사 filed Critical 솔브레인 주식회사
Priority to EP16814659.5A priority Critical patent/EP3312929B1/en
Priority to PL16814659T priority patent/PL3312929T3/en
Priority to US15/737,396 priority patent/US10720665B2/en
Priority to JP2017566809A priority patent/JP6559263B2/en
Priority claimed from KR1020160077676A external-priority patent/KR20160150604A/en
Publication of WO2016208946A1 publication Critical patent/WO2016208946A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to an electrolyte capable of improving battery characteristics of a lithium secondary battery, in particular, a cathode film formation characteristic at a high voltage, and resistance characteristics in a battery, and a lithium secondary battery comprising the same.
  • Lithium secondary batteries are not only portable power sources for mobile phones, notebook computers, digital cameras and camcorders, but also for power tools, electric bicycles, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (plug-in).
  • HEVs hybrid electric vehicles
  • plug-in plug-in hybrid electric vehicles
  • the lithium secondary battery is manufactured by using a material capable of inserting and detaching lithium ions as a negative electrode and a positive electrode, installing a porous separator between two electrodes, and then injecting a liquid electrolyte, and inserting lithium ions in the negative electrode and the positive electrode. Electricity is generated or consumed by the oxidative reduction reaction resulting from desorption.
  • An object of the present invention is to provide an electrolyte capable of improving the battery characteristics of a lithium secondary battery, in particular, the formation of a positive electrode film at high voltage and resistance characteristics in a battery.
  • Another object of the present invention is to provide a lithium secondary battery including the electrolyte.
  • the present invention provides an electrolyte for a lithium secondary battery comprising perfluoro nitrile compounds as an electrolyte additive.
  • the perfluoro nitrile compound may be any one selected from the group consisting of a perfluoro mononitrile compound, a perfluoro dinitrile compound, a perfluoro trinitrile compound, a perfluoro tetranitrile compound, and combinations thereof .
  • the perfluoro nitrile compound may be represented by the following Chemical Formulas 1 to 4.
  • N 1 to 15.
  • the perfluoro nitrile compound may be perfluorohexane-1,6-dinitrile.
  • the lithium secondary battery electrolyte may further include hexane-1,6-dinitrile (hexane-1,6-dinitrile).
  • the hexane-1,6-dinitrile may be included in an amount of 1 to 80 parts by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile.
  • the electrolyte may further include an organic solvent and a lithium salt.
  • the present invention includes a positive electrode including a positive electrode active material, a positive electrode disposed opposite to the positive electrode, a negative electrode containing a negative electrode active material, and an electrolyte interposed between the positive electrode and the negative electrode, the electrolyte is a perfluoro nitrile compound (perfluoro Provided is a lithium secondary battery including nitrile compounds) as an electrolyte additive.
  • the electrolyte additive may be included in 0.1 to 10% by weight based on the total weight of the electrolyte.
  • the perfluoro nitrile compound may be perfluorohexane-1,6-dinitrile.
  • the lithium secondary battery electrolyte may further include hexane-1,6-dinitrile (hexane-1,6-dinitrile).
  • the hexane-1,6-dinitrile may be included in an amount of 1 to 80 parts by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile.
  • the electrolyte for a secondary lithium battery according to the present invention can improve battery characteristics of a lithium secondary battery, in particular, a cathode film formation characteristic and a resistance resistance in a battery at high voltage.
  • FIG. 1 is an exploded perspective view of a rechargeable lithium battery according to one embodiment of the present invention.
  • the electrolyte according to the embodiment of the present invention includes perfluoro nitrile compounds as an electrolyte additive.
  • the perfluoro nitrile compound means a hydrocarbon compound containing at least one nitrile group and in which all hydrogen atoms are substituted with fluorine.
  • the hydrocarbon compound means a hydrocarbon compound having 1 to 15 carbon atoms consisting of carbon and hydrogen, and includes an aliphatic chain or branched hydrocarbon group and an alicyclic hydrocarbon group.
  • propane butane, pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, biphenyl and naphthalene and the like.
  • the perfluoro nitrile compound is in the group consisting of a perfluoro mononitrile compound, a perfluoro dinitrile compound, a perfluoro trinitrile compound, a perfluoro tetranitrile compound and combinations thereof according to the number of the nitrile groups It may be any one selected.
  • the perfluoro mononitrile compound may be represented by the following formula (1).
  • N 1 to 15.
  • the perfluoro mononitrile compound may be linear or branched, such as NC-CF 3 , NC-CF 2 CF 3 , NC-CFCF 3 CF 3, NC-CF 2 CF 2 CF 3 and the like.
  • perfluoro dinitrile compound may be represented by the following formula (2).
  • N 1 to 15.
  • the perfluoro dinitrile compound is NC-CF 2 -CN, NC-CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2- CN, NC-CF 2 CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 Linear perfluoro dinitrile such as -CN and branched perfluoro dinitrile such as [NC-CF 2 CF (CF 3 ) CF 2 -CN], NC-CF 2 CF 2 CF (CN) CF 3 , and It may be any one selected from the group consisting of a combination thereof.
  • perfluoro trinitrile compound may be represented by the following formula (3).
  • n 1 to n 3 are each independently 1 to 15.
  • the perfluoro trinitrile compound is CF- (CF 2 -CN) 2 (CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 CF 2 CF 2 -CN) or CF- (CF 2 -CN) 3 , CF- (CF 2 -CN) 2 (CF 2 CF 2 -CN), CF- (CF 2 -CN) (CF 2 CF 2 -CN) 2 , CF- (CF 2 -CN) (CF 2 CF 2- CN) (CF 2 CF 2 CF 2 -CN) or the like.
  • perfluoro tetranitrile compound may be represented by the following formula (4).
  • N 1 to n 4 are each independently 1 to 15;
  • the perfluoro trinitrile compound is C- (CF 2 -CN) 3 (CF 2 CF 2 -CN), C- (CF 2 -CN) 3 (CF 2 CF 2 CF 2 -CN), C -(CF 2 -CN) 3 (CF 2 CF 2 CF 2 CF 2 -CN), C- (CF 2 -CN) 3 (CF 2 CF 2 CF 2 CF 2 -CN), C- (CF 2 -CN) 3 (CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 -CN) or C- (CF 2 -CN) 4 , Or C- (CF 2 -CN) 3 (CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 -CN) 2, or the like.
  • an electrolyte for a lithium battery including at least one electrolyte additive selected from the group consisting of compounds represented by Formulas 1 to 4.
  • the nitrile group in the compounds represented by Chemical Formulas 1 to 4 helps to form a film on the (-CN) anode, and fluorine (F) rich in electrons fills the insufficient electrons to balance the anode.
  • an alkylene group of 1 to 15 carbon atoms may be more preferable, among these alkylene groups of 4 to 10 carbon atoms than More preferred.
  • the perfluoro nitrile-based compound of Formula 1 may be a perfluoropentane nitrile (Perfluoropentanenitrile), the perfluoro dinitrile-based compound of Formula 2 is a perfluorohexane-1,6-dinitrile (Perfluorohexane-1,6-dinitrile), wherein the perfluoro trinitrile-based compound of Formula 3 is 3-cyano difluoro methyl-2,2,3,4,4-pentafluoro pentane di Nitrile (3- (cyano difluoro methyl) -2,2,3,4,4-penta fluoro pentane dinitrile), wherein the perfluoro tetranitrile-based compound of Formula 4 is 3,3-biscyano difluoro Chloromethyl-2,2,4,4-tetrafluoropentane dinitrile (3,3-bis (cyano difluoromethyl) -2,2,4,4-tetra fluoro pen
  • the perfluorohexane-1,6-dinitrile may be used with hexane-1,6-dinitrile (hexane-1,6-dinitrile).
  • hexane-1,6-dinitrile hexane-1,6-dinitrile
  • battery characteristics in particular, high voltage life characteristics and storage characteristics of a lithium secondary battery may be further improved.
  • a synergistic effect can be obtained in which recovery capacity and swelling characteristics are further improved.
  • the hexane-1,6-dinitrile may be included in an amount of 1 to 80 parts by weight, specifically, 5 to 70 parts by weight, and more, based on 100 parts by weight of the perfluorohexane-1,6-dinitrile. Specifically, it may be included in an amount of 8 to 50 parts by weight.
  • the content of the hexane-1,6-dinitrile is less than 1 part by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile, the synergistic effect may not occur because sufficient electrons are not supplied to the positive electrode during discharge. If it is more than 80 parts by weight, a thick film may be formed on the anode, thereby greatly increasing resistance.
  • the electrolyte additive including the perfluoronitrile compound of Chemical Formulas 1 to 4 may be included in an amount of 0.1 to 10% by weight, preferably 0.2 to 7% by weight, and more preferably, based on the total weight of the electrolyte. 0.5 to 5% by weight may be included.
  • the electrolyte additive is less than 0.1% by weight, there may be no effect due to insufficient supply of electrons to the positive electrode during discharging. If the electrolyte additive is more than 10% by weight, a thick film may be formed on the positive electrode to greatly increase resistance.
  • the perfluoro nitrile compound may improve battery characteristics, particularly life characteristics and low resistance characteristics of a lithium secondary battery when used as an electrolyte additive.
  • the electrolyte may further include an organic solvent and a lithium salt in addition to the electrolyte additive described above.
  • the organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move.
  • the organic solvent may be an ester solvent, an ether solvent, a ketone solvent, an aromatic hydrocarbon solvent, an alkoxyalkane solvent, a carbonate solvent, or the like, and may be used alone or in combination of two or more thereof.
  • ester solvent examples include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, dimethyl acetate, methyl propionate, and ethyl prop.
  • ether solvents include dibutyl ether, tetraglyme, 2-methyltetrahydrofuran, tetrahydrofuran, and the like.
  • ketone solvent examples include cyclohexanone.
  • aromatic hydrocarbon-based organic solvent examples include benzene, fluorobenzene, chlorobenzene, iodobenzene, toluene, fluorotoluene, or xylene (xylene) etc. are mentioned.
  • alkoxyalkane solvent examples include dimethoxy ethane or diethoxy ethane.
  • the carbonate solvent examples include dimethyl carbonate (dimethyl carbonate, DMC), diethyl carbonate (DEC), dipropyl carbonate (dipropyl carbonate, DPC), methyl propyl carbonate (methyl propyl carbonate, MPC), ethyl propyl carbonate (ethyl propyl carbonate, EPC) , Methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or fluoro Ethylene carbonate (FEC) etc. are mentioned.
  • a carbonate solvent is preferably used as the organic solvent, and among the carbonate solvents, a carbonate organic solvent having a high dielectric constant having a high ionic conductivity that can increase the charge / discharge performance of a battery, and the intrinsic It may be preferable to use a mixture of a low-viscosity carbonate-based organic solvent capable of appropriately adjusting the viscosity of the organic solvent.
  • an organic solvent having a high dielectric constant selected from the group consisting of ethylene carbonate, propylene carbonate and mixtures thereof, and an organic solvent having a low viscosity selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate and mixtures thereof can be mixed and used.
  • the high dielectric constant organic solvent and the low viscosity organic solvent may be mixed and used in a volume ratio of 2: 8 to 8: 2, and more specifically, ethylene carbonate or propylene carbonate; Ethyl methyl carbonate; And dimethyl carbonate or diethyl carbonate can be used by mixing in a volume ratio of 5: 1: 1 to 2: 5: 3, preferably can be used by mixing in a volume ratio of 3: 5: 2.
  • the lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery.
  • the lithium salt is LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (C 2 F 5 SO 3 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , LiN (C a F 2a + 1 SO 2 ) (C b F 2b + 1 SO 2 ) (where a and b are natural numbers , Preferably 1 ⁇ a ⁇ 20, and 1 ⁇ b ⁇ 20), LiCl, LiI, LiB (C 2 O 4 ) 2, and mixtures thereof may be used, preferably lithium hexa It is preferable to use fluorophosphate (LiPF 6 ).
  • the lithium salt When the lithium salt is dissolved in an electrolyte, the lithium salt may function as a source of lithium ions in the lithium secondary battery and may promote the movement of lithium ions between the positive electrode and the negative electrode. Accordingly, the lithium salt is preferably contained at a concentration of approximately 0.6M to 2M in the electrolyte. When the concentration of the lithium salt is less than 0.6M, the conductivity of the electrolyte may be lowered and the performance of the electrolyte may be lowered. When the concentration of the lithium salt is higher than 2M, the viscosity of the electrolyte may be increased, thereby reducing the mobility of lithium ions. In consideration of the conductivity of the electrolyte and the mobility of the lithium ions, the lithium salt may be more preferably adjusted to about 0.7M to 1.6M in the electrolyte.
  • the electrolyte may further include additives (hereinafter, referred to as other additives) that can be generally used in the electrolyte for the purpose of improving the life characteristics of the battery, suppressing the reduction of the battery capacity, and improving the discharge capacity of the battery. have.
  • additives hereinafter, referred to as other additives
  • Examples of the other additives include vinylene carbonate (vinylenecarbonate, VC), metal fluoride (metal fluoride, for example, LiF, RbF, TiF, AgF , AgF 2, BaF 2, CaF 2, CdF 2, FeF 2, HgF 2 , Hg 2 F 2 , MnF 2 , NiF 2 , PbF 2 , SnF 2 , SrF 2 , XeF 2 , ZnF 2 , AlF 3 , BF 3 , BiF 3 , CeF 3 , CrF 3 , DyF 3 , EuF 3 , GaF 3, GdF 3, FeF 3 , HoF 3, InF 3, LaF 3, LuF 3, MnF 3, NdF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF 3, TmF 3, YF 3 , YbF 3, TIF 3, CeF 4, GeF 4, HfF 4, SiF 4, SnF 4, TiF 4, VF 4, ZrF4
  • the other additives may be included in 0.1 to 20% by weight relative to the total weight of the electrolyte, it is preferable to include 0.2 to 5% by weight.
  • Lithium secondary battery according to an embodiment of the present invention can be classified into a lithium ion battery, a lithium ion polymer battery and a lithium polymer battery according to the type of separator and electrolyte used, cylindrical, square, coin type, pouch type depending on the form Etc., and may be classified into a bulk type and a thin film type according to the size.
  • the electrolyte according to the embodiment of the present invention may be particularly excellent for application to a lithium ion battery, an aluminum laminated battery and a lithium polymer battery.
  • the lithium secondary battery includes a positive electrode including a positive electrode active material disposed opposite to each other, a negative electrode including a negative electrode active material, and the electrolyte interposed between the positive electrode and the negative electrode.
  • a lithium secondary battery 1 is an exploded perspective view of a lithium secondary battery 1 according to an embodiment of the present invention.
  • a lithium secondary battery 1 according to another embodiment of the present invention includes a separator 7 between a negative electrode 3, a positive electrode 5, the negative electrode 3, and a positive electrode 5.
  • the electrode assembly 9 placing it in the case 15, and injecting a nonaqueous electrolyte so that the cathode 3, the anode 5, and the separator 7 are impregnated with the electrolyte. have.
  • Conductive lead members 10 and 13 may be attached to the negative electrode 3 and the positive electrode 5, respectively, and the lead members 10 and 13 may be attached to the positive electrode 5, respectively. And current generated at the cathode 3 to the anode and cathode terminals.
  • the positive electrode 5 is prepared by mixing a positive electrode active material, a conductive agent and a binder to prepare a composition for forming a positive electrode active material layer, and then applying the composition for forming a positive electrode active material layer to a positive electrode current collector such as aluminum foil and rolling the same. can do.
  • a compound (lithiated intercalation compound) capable of reversible intercalation and deintercalation of lithium may be used.
  • the olivine-type lithium metal compound represented by the following formula (5) can be used.
  • M and M ' are each independently Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B and combinations thereof It is an element selected from the group consisting of, wherein X is an element selected from the group consisting of P, As, Bi, Sb, Mo and combinations thereof, wherein Y is selected from the group consisting of F, S and combinations thereof Element, 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0 ⁇ x + y + z ⁇ 2, and 0 ⁇ w ⁇ 0.5.
  • LiCoO 2 , LiMnO 2 , LiMn 2 O 4 , LiNiO 2 , LiNi x Mn (1-x) O 2 (where 0 ⁇ x ⁇ 1) and LiM can improve the capacity characteristics and stability of the battery.
  • lx M 2y O 2 (where 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x + y ⁇ 1, M 1 and M 2 are each independently selected from the group consisting of Al, Sr, Mg and La) One), and mixtures thereof.
  • the negative electrode 3 is prepared by mixing a negative electrode active material, a binder, and optionally a conductive agent similarly to the positive electrode 5 to prepare a composition for forming a negative electrode active material layer, and then applying the same to a negative electrode current collector such as copper foil. Can be.
  • the negative electrode active material a compound capable of reversible intercalation and deintercalation of lithium may be used.
  • the negative electrode active material may be a carbonaceous material such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, or the like.
  • a metallic compound capable of alloying with lithium, or a composite including a metallic compound and a carbonaceous material may also be used as the negative electrode active material.
  • the metal capable of alloying with lithium at least one of Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, and Al alloy may be used.
  • a metal lithium thin film may be used as the negative electrode active material.
  • any one selected from the group consisting of crystalline carbon, amorphous carbon, carbon composite, lithium metal, an alloy containing lithium, and mixtures thereof may be used in view of high stability.
  • the electrolyte is as described above in the section on the electrolyte, the description thereof is omitted.
  • the lithium secondary battery may be manufactured by a conventional method, and thus detailed description thereof will be omitted.
  • the pouch type lithium secondary battery has been described as an example, but the technology of the present invention is not limited to the pouch type lithium secondary battery, and may be any shape as long as it can operate as a battery.
  • the lithium secondary battery including the electrolyte according to the embodiment of the present invention can exhibit low DC-IR characteristics, high high temperature storage characteristics, and improved output characteristics, so that a fast charging speed is required for mobile phones and laptops. It can be useful in portable devices such as computers, digital cameras and camcorders, in the field of electric vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and medium and large energy storage systems. have.
  • HEVs hybrid electric vehicles
  • PHEVs plug-in hybrid electric vehicles
  • medium and large energy storage systems have.
  • LiCoO 2 as a positive electrode active material
  • carbon black as a conductive material
  • PVDF polyvinylidene fluoride
  • n-methyl-2-pyrrolidone n-methyl as a solvent
  • NMP -2-pyrrolidone
  • a slurry prepared by mixing artificial graphite MCMB (mesocarbon microbead), carbon black (carbon black), PVDF as a binder, and NMP as a solvent was coated on a copper (Cu) substrate.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC dimethyl carbonate
  • An electrolyte solution was prepared by adding 1 wt% of Perfluoropentanenitrile as an electrolyte solution additive with respect to the total weight of the mixed solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC dimethyl carbonate
  • An electrolyte solution was prepared by adding 1% by weight of perfluorohexane-1,6-dinitrile as an electrolyte solution additive with respect to the total weight of the mixed solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC dimethyl carbonate
  • 3-cyanodifluoromethyl-2,2,3,4,4-pentaruropentanedinitrile 3- (cyanodifluoromethyl) -2,2,3,4,4- as an electrolyte additive with respect to the total weight of the mixed solution 1% by weight of pentafluoropentanedinitrile) was added to prepare an electrolyte solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC dimethyl carbonate
  • An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in Formula 1 as an electrolyte solution additive with respect to the total weight of the mixed solution.
  • a lithium secondary battery in the form of an aluminum pouch was manufactured using the prepared electrolyte and the positive electrode and negative electrode prepared above.
  • An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in Formula 2 as an electrolyte solution additive with respect to the total weight of the mixed solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in Formula 3 as an electrolyte solution additive with respect to the total weight of the mixed solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in the general formula (4) as an electrolyte solution additive with respect to the total weight of the mixed solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC dimethyl carbonate
  • An electrolyte solution was prepared by adding 1% by weight of hexane-1,6-dinitrile as an electrolyte additive with respect to the total weight of the mixed solution.
  • An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
  • the batteries prepared in Comparative Examples 1 to 5 and Examples 1 to 5 were charged with 1.0C-CCCV-4.45V and 0.04C, respectively, and rested for 10 minutes until they reached 1.0C-CC-3.0V. Discharged and rested for 10 minutes. The efficiency is measured while repeating the cycle 300 times and is shown in Table 1. Moreover, the data of Example 2, the comparative example 2, and the comparative example 5 are shown in FIG.
  • the present invention can improve the battery characteristics of the lithium secondary battery, in particular, the positive electrode film formation characteristic and the resistance resistance in the battery at high voltage.
  • the battery prepared in Examples 2, 5 and Comparative Example 2 was charged to 4.45V and then stored at 60 ° C. for 4 weeks, and then the remaining discharge solution of the battery was measured to measure the recovery capacity. By measuring the swelling (swelling) characteristics were measured, the results are shown in Table 2 and Table 3, respectively.
  • the hexane-1,6-dinitrile used in Comparative Example 5 is a recovery capacity and swell compared to the perfluorohexane-1,6-dinitrile used in Example 2
  • the perfluorohexane-1,6- Compared with Example 2 using only dinitrile alone, even though the total content of the electrolyte additive is the same, it can be seen that a synergistic effect of further improving recovery capacity and swelling characteristics is obtained.
  • cathode 5 anode
  • the present invention relates to an electrolyte for a lithium secondary battery and a lithium secondary battery including the same, wherein the electrolyte for a lithium secondary battery may improve battery characteristics of a lithium secondary battery, in particular, a cathode film formation characteristic and a battery resistance characteristic at high voltage.

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Abstract

The present invention relates to an electrolyte for a lithium secondary battery, containing, as an electrolyte additive, at least one compound selected from the group consisting of compounds represented by chemical formulas 1 to 4 below, and can provide a lithium secondary battery which has improved anodic film forming characteristics and battery resistance characteristics at high voltages.

Description

리튬 이차 전지용 전해질 및 이를 포함하는 리튬 이차 전지Electrolyte for lithium secondary battery and lithium secondary battery comprising same
본 발명은 리튬 이차 전지의 전지 특성, 특히 고전압에서의 양극 피막 형성 특성 및 전지 내 저항 특성을 향상시킬 수 있는 전해질 및 이를 포함하는 리튬 이차 전지에 관한 것이다.The present invention relates to an electrolyte capable of improving battery characteristics of a lithium secondary battery, in particular, a cathode film formation characteristic at a high voltage, and resistance characteristics in a battery, and a lithium secondary battery comprising the same.
리튬 이차 전지는 휴대전화, 노트북 컴퓨터, 디지털카메라 및 캠코더 등의 휴대용 전원으로서뿐만 아니라 전동공구(power tool), 전기자전거, 하이브리드 전기자동차(hybrid electric vehicle, HEV), 플러그인 하이브리드 전기자동차(plug-in HEV, PHEV) 등의 중대형 전원으로 그 응용이 급속히 확대되고 있다. 이와 같은 응용분야의 확대 및 수요의 증가에 따라 전지의 외형적인 모양과 크기도 다양하게 변하고 있으며, 기존의 소형전지에서 요구되는 특성보다 더욱 우수한 성능과 안정성이 요구되고 있다. 이러한 요구에 부응하기 위해서는 전지 구성 성분들은 대전류가 흐르는 조건에서 전지의 성능구현이 안정적으로 이루어 져야한다.Lithium secondary batteries are not only portable power sources for mobile phones, notebook computers, digital cameras and camcorders, but also for power tools, electric bicycles, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (plug-in). The application is expanding rapidly with medium and large power supplies such as HEV and PHEV. As the application field expands and the demand increases, the appearance and size of the battery are also changed in various ways, and more excellent performance and stability are required than the characteristics required in the conventional small battery. In order to meet these demands, battery components must be stable in battery performance under high current conditions.
리튬 이차 전지는 리튬 이온의 삽입 및 탈리가 가능한 물질을 음극 및 양극으로 사용하고, 두 전극 사이에 다공성 분리막을 설치한 후 액체 전해질을 주입시켜 제조되며, 상기 음극 및 양극에서의 리튬 이온의 삽입 및 탈리에 따른 산 화 환원반응에 의해 전기가 생성 또는 소비된다.The lithium secondary battery is manufactured by using a material capable of inserting and detaching lithium ions as a negative electrode and a positive electrode, installing a porous separator between two electrodes, and then injecting a liquid electrolyte, and inserting lithium ions in the negative electrode and the positive electrode. Electricity is generated or consumed by the oxidative reduction reaction resulting from desorption.
리튬 이온 전지의 출력특성, 사이클특성, 보존특성 등의 전지특성을 개선하기 위해 전해질 구비 성분으로서 비수계 용매나 첨가제에 대한 다양한 검토가 이루어지고 있다. 또한, 전지 성능 향상을 위하여 특정 화합물을 첨가제로서 전해질에 첨가하는 경우에도 대부분의 전지성능 중 일부 항목의 성능 향상은 기대 할 수 있으나 다른 항목의 성능을 오히려 감소시키게 되는 등의 문제점이 있다.In order to improve battery characteristics such as output characteristics, cycle characteristics, and storage characteristics of lithium ion batteries, various studies have been made on non-aqueous solvents and additives as electrolyte-containing components. In addition, even when a specific compound is added to the electrolyte as an additive to improve battery performance, some of the battery performance can be expected to improve performance, but there are problems such as reducing the performance of other items.
본 발명의 목적은 리튬 이차 전지의 전지 특성, 특히 고전압에서의 양극 피막 형성 특성 및 전지 내 저항 특성을 향상시킬 수 있는 전해질을 제공하는 것이다.SUMMARY OF THE INVENTION An object of the present invention is to provide an electrolyte capable of improving the battery characteristics of a lithium secondary battery, in particular, the formation of a positive electrode film at high voltage and resistance characteristics in a battery.
본 발명의 다른 목적은 상기 전해질을 포함하는 리튬 이차 전지를 제공하는 것이다. Another object of the present invention is to provide a lithium secondary battery including the electrolyte.
상기 목적을 달성하기 위하여, 본 발명은 퍼플루오로 니트릴 화합물(perfluoro nitrile compounds)을 전해질 첨가제로 포함하는 리튬 이차 전지용 전해질을 제공한다.In order to achieve the above object, the present invention provides an electrolyte for a lithium secondary battery comprising perfluoro nitrile compounds as an electrolyte additive.
상기 퍼플루오로 니트릴 화합물은 퍼플루오로 모노니트릴 화합물, 퍼플루오로 디니트릴 화합물, 퍼플루오로 트리니트릴 화합물, 퍼플루오로 테트라니트릴 화합물 및 이들의 조합으로 이루어진 군에서 선택되는 어느 하나인 것일 수 있다.The perfluoro nitrile compound may be any one selected from the group consisting of a perfluoro mononitrile compound, a perfluoro dinitrile compound, a perfluoro trinitrile compound, a perfluoro tetranitrile compound, and combinations thereof .
상기 퍼플루오로 니트릴 화합물은 하기 화학식 1 내지 4로 표시되는 것일 수 있다.The perfluoro nitrile compound may be represented by the following Chemical Formulas 1 to 4.
[화학식 1][Formula 1]
Figure PCTKR2016006587-appb-I000001
Figure PCTKR2016006587-appb-I000001
[화학식 2][Formula 2]
Figure PCTKR2016006587-appb-I000002
Figure PCTKR2016006587-appb-I000002
[화학식 3][Formula 3]
Figure PCTKR2016006587-appb-I000003
Figure PCTKR2016006587-appb-I000003
[화학식 4][Formula 4]
Figure PCTKR2016006587-appb-I000004
Figure PCTKR2016006587-appb-I000004
상기 n은 1 내지 15이다.N is 1 to 15.
상기 퍼플루오로 니트릴 화합물은 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile)일 수 있다. The perfluoro nitrile compound may be perfluorohexane-1,6-dinitrile.
상기 리튬 이차 전지용 전해질은 헥산-1,6-디니트릴(hexane-1,6-dinitrile)을 더 포함할 수 있다. The lithium secondary battery electrolyte may further include hexane-1,6-dinitrile (hexane-1,6-dinitrile).
상기 헥산-1,6-디니트릴은 상기 퍼플루오로헥산-1,6-디니트릴 100 중량부에 대하여 1 내지 80 중량부로 포함될 수 있다.The hexane-1,6-dinitrile may be included in an amount of 1 to 80 parts by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile.
상기 전해질은 유기 용매 및 리튬염을 더 포함하는 것일 수 있다.The electrolyte may further include an organic solvent and a lithium salt.
또한, 본 발명은 양극 활물질을 포함하는 양극, 상기 양극과 대향 배치되며, 음극 활물질을 포함하는 음극, 그리고 상기 양극과 음극 사이에 개재되는 전해질을 포함하며, 상기 전해질은 퍼플루오로 니트릴 화합물(perfluoro nitrile compounds)을 전해질 첨가제로 포함하는 리튬 이차 전지를 제공한다.In addition, the present invention includes a positive electrode including a positive electrode active material, a positive electrode disposed opposite to the positive electrode, a negative electrode containing a negative electrode active material, and an electrolyte interposed between the positive electrode and the negative electrode, the electrolyte is a perfluoro nitrile compound (perfluoro Provided is a lithium secondary battery including nitrile compounds) as an electrolyte additive.
상기 전해질 첨가제는, 상기 전해질 총 중량에 대하여 0.1 내지 10 중량%로 포함되는 것일 수 있다.The electrolyte additive may be included in 0.1 to 10% by weight based on the total weight of the electrolyte.
상기 퍼플루오로 니트릴 화합물은 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile)일 수 있다. The perfluoro nitrile compound may be perfluorohexane-1,6-dinitrile.
상기 리튬 이차 전지용 전해질은 헥산-1,6-디니트릴(hexane-1,6-dinitrile)을 더 포함할 수 있다. The lithium secondary battery electrolyte may further include hexane-1,6-dinitrile (hexane-1,6-dinitrile).
상기 헥산-1,6-디니트릴은 상기 퍼플루오로헥산-1,6-디니트릴 100 중량부에 대하여 1 내지 80 중량부로 포함될 수 있다.The hexane-1,6-dinitrile may be included in an amount of 1 to 80 parts by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile.
본 발명에 따른 이차 리튬 전지용 전해질은 리튬 이차 전지의 전지 특성, 특히 고전압에서의 양극 피막 형성 특성 및 전지 내 저항 특성을 향상시킬 수 있다.The electrolyte for a secondary lithium battery according to the present invention can improve battery characteristics of a lithium secondary battery, in particular, a cathode film formation characteristic and a resistance resistance in a battery at high voltage.
도 1은 본 발명의 일 실시예에 따른 리튬 이차 전지의 분해 사시도이다.1 is an exploded perspective view of a rechargeable lithium battery according to one embodiment of the present invention.
도 2는 본 발명의 실시예 및 비교예에 따른 리튬 이차 전지의 수명 특성을 나타내는 그래프이다.2 is a graph showing the life characteristics of the lithium secondary battery according to the Examples and Comparative Examples of the present invention.
본 발명은 다양한 변환을 가할 수 있고 여러 가지 실시예를 가질 수 있는 바, 특정 실시예를 예시하고 상세한 설명에 상세하게 설명하고자 한다. 그러나, 이는 본 발명을 특정한 실시 형태에 대해 한정하려는 것이 아니며, 본 발명의 사상 및 기술 범위에 포함되는 모든 변환, 균등물 내지 대체물을 포함하는 것으로 이해되어야 한다.As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention.
본 발명에서 사용한 용어는 단지 특정한 실시예를 설명하기 위해 사용된 것으로, 본 발명을 한정하려는 의도가 아니다. 단수의 표현은 문맥상 명백하게 다르게 뜻하지 않는 한, 복수의 표현을 포함한다. 본 발명에서, 포함하다 또는 가지다 등의 용어는 명세서상에 기재된 특징, 숫자, 단계, 동작, 구성요소, 부품 또는 이들을 조합한 것이 존재함을 지정하려는 것이지, 하나 또는 그 이상의 다른 특징들이나 숫자, 단계, 동작, 구성요소, 부품 또는 이들을 조합한 것들의 존재 또는 부가 가능성을 미리 배제하지 않는 것으로 이해되어야 한다.The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, the terms including or having are intended to indicate that there is a feature, number, step, operation, component, part, or a combination thereof described in the specification, but one or more other features or numbers, step It is to be understood that the present invention does not exclude in advance the possibility of the presence or the addition of operations, components, components, or a combination thereof.
또한, 본 명세서에서 사용한 용어 이들의 조합이란 특별한 언급이 없는 한, 둘 이상의 치환기가 단일 결합 또는 연결기로 결합되어 있거나, 둘 이상의 치환기가 축합하여 연결되어 있는 것을 의미한다.In addition, the terms used in this specification, unless otherwise indicated, means that two or more substituents are bonded to a single bond or a linking group, or two or more substituents are condensed to each other.
본 발명의 일 실시예에 따른 전해질은, 퍼플루오로 니트릴 화합물 (perfluoro nitrile compounds)을 전해질 첨가제로 포함한다. 여기서, 상기 퍼플루오로 니트릴 화합물이란, 한 개 이상의 니트릴기를 포함하며, 전체 수소 원자가 플루오르로 치환된 탄화수소 화합물을 의미한다. 또한, 상기 탄화수소 화합물은 탄소와 수소로 이루어진 탄소수 1 내지 15의 탄화수소 화합물을 의미하며, 지방족 사슬형 또는 분지형 탄화수소기 및 알리사이클릭 탄화수소기를 포함한다. 구체적인 예로는 프로판, 부탄, 펜탄, 헥산, 헵탄, 옥탄, 시클로헥산, 벤젠, 톨루엔, 크실렌, 비페닐 및 나프탈렌 등을 포함한다.The electrolyte according to the embodiment of the present invention includes perfluoro nitrile compounds as an electrolyte additive. Here, the perfluoro nitrile compound means a hydrocarbon compound containing at least one nitrile group and in which all hydrogen atoms are substituted with fluorine. In addition, the hydrocarbon compound means a hydrocarbon compound having 1 to 15 carbon atoms consisting of carbon and hydrogen, and includes an aliphatic chain or branched hydrocarbon group and an alicyclic hydrocarbon group. Specific examples include propane, butane, pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, biphenyl and naphthalene and the like.
상기 퍼플루오로 니트릴 화합물은 상기 니트릴기의 개수에 따라, 퍼플루오로 모노니트릴 화합물, 퍼플루오로 디니트릴 화합물, 퍼플루오로 트리니트릴 화합물, 퍼플루오로 테트라니트릴 화합물 및 이들의 조합으로 이루어진 군에서 선택되는 어느 하나인 것일 수 있다.The perfluoro nitrile compound is in the group consisting of a perfluoro mononitrile compound, a perfluoro dinitrile compound, a perfluoro trinitrile compound, a perfluoro tetranitrile compound and combinations thereof according to the number of the nitrile groups It may be any one selected.
구체적으로, 상기 퍼플루오로 모노니트릴 화합물을 하기 화학식 1로 표시될 수 있다.Specifically, the perfluoro mononitrile compound may be represented by the following formula (1).
[화학식 1][Formula 1]
Figure PCTKR2016006587-appb-I000005
Figure PCTKR2016006587-appb-I000005
상기 n은 1 내지 15이다.N is 1 to 15.
보다 구체적으로, 상기 퍼플루오로 모노니트릴 화합물은 NC-CF3, NC-CF2CF3 , NC-CFCF3CF3, NC-CF2CF2CF3 등의 직쇄형상 또는 분기형상일 수 있다.More specifically, the perfluoro mononitrile compound may be linear or branched, such as NC-CF 3 , NC-CF 2 CF 3 , NC-CFCF 3 CF 3, NC-CF 2 CF 2 CF 3 and the like.
또한, 상기 퍼플루오로 디니트릴 화합물은 하기 화학식 2로 표시될 수 있다.In addition, the perfluoro dinitrile compound may be represented by the following formula (2).
[화학식 2][Formula 2]
Figure PCTKR2016006587-appb-I000006
Figure PCTKR2016006587-appb-I000006
상기 n은 1 내지 15이다.N is 1 to 15.
보다 구체적으로, 상기 퍼플루오로 디니트릴 화합물은 NC-CF2-CN, NC-CF2CF2-CN, NC-CF2CF2CF2-CN, NC-CF2CF2CF2CF2-CN, NC-CF2CF2CF2CF2CF2-CN, NC-CF2CF2CF2CF2CF2CF2-CN, NC-CF2CF2CF2CF2CF2CF2CF2-CN 등의 직쇄형상 퍼플루오르 디니트릴 및 [NC-CF2CF(CF3)CF2-CN], NC-CF2CF2CF2CF(CN)CF3 등의 분기형상 퍼플루오르 디니트릴 및 이들의 조합으로 이루어진 군에서 선택되는 어느 하나일 수 있다. More specifically, the perfluoro dinitrile compound is NC-CF 2 -CN, NC-CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 CF 2- CN, NC-CF 2 CF 2 CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 -CN, NC-CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 Linear perfluoro dinitrile such as -CN and branched perfluoro dinitrile such as [NC-CF 2 CF (CF 3 ) CF 2 -CN], NC-CF 2 CF 2 CF 2 CF (CN) CF 3 , and It may be any one selected from the group consisting of a combination thereof.
또한, 상기 퍼플루오로 트리니트릴 화합물은 하기 화학식 3으로 표시될 수 있다.In addition, the perfluoro trinitrile compound may be represented by the following formula (3).
[화학식 3][Formula 3]
Figure PCTKR2016006587-appb-I000007
Figure PCTKR2016006587-appb-I000007
상기 n1 내지 n3은 각각 독립적으로 1 내지 15이다.Wherein n 1 to n 3 are each independently 1 to 15.
보다 구체적으로, 상기 퍼플루오로 트리니트릴 화합물은 CF-(CF2-CN)2(CF2CF2-CN), CF-(CF2-CN)2(CF2CF2CF2-CN), CF-(CF2-CN)2(CF2CF2CF2CF2-CN), CF-(CF2-CN)2(CF2CF2CF2CF2CF2-CN) 또는 CF-(CF2-CN)3, CF-(CF2-CN)2(CF2CF2-CN), CF-(CF2-CN)(CF2CF2-CN)2, CF-(CF2-CN)(CF2CF2-CN)(CF2CF2CF2-CN) 등의 분기형상일 수 있다.More specifically, the perfluoro trinitrile compound is CF- (CF 2 -CN) 2 (CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 CF 2 CF 2 CF 2 -CN) or CF- (CF 2 -CN) 3 , CF- (CF 2 -CN) 2 (CF 2 CF 2 -CN), CF- (CF 2 -CN) (CF 2 CF 2 -CN) 2 , CF- (CF 2 -CN) (CF 2 CF 2- CN) (CF 2 CF 2 CF 2 -CN) or the like.
또한, 상기 퍼플루오로 테트라니트릴 화합물을 하기 화학식 4로 표시될 수 있다.In addition, the perfluoro tetranitrile compound may be represented by the following formula (4).
[화학식 4][Formula 4]
Figure PCTKR2016006587-appb-I000008
Figure PCTKR2016006587-appb-I000008
상기 n1 내지 n4는 각각 독립적으로 1 내지 15이다.N 1 to n 4 are each independently 1 to 15;
보다 구체적으로 상기 퍼플루오로 트리니트릴 화합물은 C-(CF2-CN)3(CF2CF2-CN), C-(CF2-CN)3(CF2CF2CF2-CN), C-(CF2-CN)3(CF2CF2CF2CF2-CN), C-(CF2-CN)3(CF2CF2CF2CF2CF2-CN), C-(CF2-CN)3(CF2CF2CF2CF2CF2CF2CF2CF2-CN) 또는 C-(CF2-CN)4, C-(CF2-CN)3(CF2CF2-CN), CF-(CF2-CN)2(CF2CF2-CN)2 등의 분기형상일 수 있다.More specifically, the perfluoro trinitrile compound is C- (CF 2 -CN) 3 (CF 2 CF 2 -CN), C- (CF 2 -CN) 3 (CF 2 CF 2 CF 2 -CN), C -(CF 2 -CN) 3 (CF 2 CF 2 CF 2 CF 2 -CN), C- (CF 2 -CN) 3 (CF 2 CF 2 CF 2 CF 2 CF 2 -CN), C- (CF 2 -CN) 3 (CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 -CN) or C- (CF 2 -CN) 4 , Or C- (CF 2 -CN) 3 (CF 2 CF 2 -CN), CF- (CF 2 -CN) 2 (CF 2 CF 2 -CN) 2, or the like.
전지 내 충전이 일어나게 되면 양극에서 탈리튬(delithiation)이 일어나게 되고, 이에 따라 양극은 밸런스가 무너지고 성능열화가 발생한다. 종래에는 양극피막 첨가제로 숙시노 니트릴(succino nitrile, SN)을 첨가하여 밸런스를 맞춘다. 그러나 고전압 하에서는 더 많은 탈리튬화가 일어나게 되어 상기 SN으로는 차지 밸런스(charge balance)를 맞추기 어려워진다. 본 발명에서는 화학식 1 내지 4로 표시되는 화합물로 이루어진 군으로부터 선택된 1 종 이상의 전해질 첨가제를 포함하는 리튬 전지용 전해질을 사용하여 상기 문제점을 해결할 수 있다.When the battery is charged, delithiation occurs at the positive electrode, which causes the positive electrode to lose balance and deteriorate in performance. Conventionally, succino nitrile (SN) is added as an anode coating additive to balance. However, at higher voltages more delithiation occurs, making it difficult to balance charge with the SN. In the present invention, the above problems can be solved by using an electrolyte for a lithium battery including at least one electrolyte additive selected from the group consisting of compounds represented by Formulas 1 to 4.
리튬 전지는 고전압 충전시 양극에서 많은 리튬 이온이 빠져나오게 되고, 이에 양극에 전하수 균형이 무너지게 된다. 이에 상기 화학식 1 내지 4로 표시되는 화합물 중 니트릴기는(-CN) 양극에 피막을 형성하게끔 도와주고 전자가 풍부한 플루오르(F)는 부족한 전자를 채워 양극의 균형을 맞출 수 있게 한다.In a lithium battery, a large amount of lithium ions are ejected from the positive electrode during high voltage charging, and thus the charge number balance is broken at the positive electrode. Accordingly, the nitrile group in the compounds represented by Chemical Formulas 1 to 4 helps to form a film on the (-CN) anode, and fluorine (F) rich in electrons fills the insufficient electrons to balance the anode.
상기 화학식 1 내지 4에서, 상기 전해질 첨가제의 사용에 따른 전지 특성 개선효과의 개선 정도를 고려할 때, 탄소수 1 내지 15의 알킬렌기가 보다 바람직할 수 있으며, 이중에서도 탄소수 4 내지 10 의 알킬렌기가 보다 더 바람직할 수 있다. In the above Chemical Formulas 1 to 4, considering the degree of improvement of the battery characteristics improvement effect of the use of the electrolyte additive, an alkylene group of 1 to 15 carbon atoms may be more preferable, among these alkylene groups of 4 to 10 carbon atoms than More preferred.
구체적으로, 상기 화학식 1의 퍼플루오로 니트릴계 화합물은 퍼플루오로 펜테인 니트릴(Perfluoropentanenitrile)일 수 있고, 상기 화학식 2의 퍼플루오로 디니트릴계 화합물은 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile)일 수 있고, 상기 화학식 3의 퍼플루오로 트리니트릴계 화합물은 3-시아노 디플루오로 메틸-2,2,3,4,4-펜타플루오로 펜테인 디니트릴(3-(cyano difluoro methyl) -2,2,3,4,4-penta fluoro pentane dinitrile)일 수 있고, 상기 화학식 4의 퍼플루오로 테트라니트릴계 화합물은 3,3-비스시아노 디플루오로메틸-2,2,4,4-테트라 플루오로 펜테인 디니트릴(3,3-bis(cyano difluoromethyl)-2,2,4,4-tetra fluoro pentane dinitrile)일 수 있다.Specifically, the perfluoro nitrile-based compound of Formula 1 may be a perfluoropentane nitrile (Perfluoropentanenitrile), the perfluoro dinitrile-based compound of Formula 2 is a perfluorohexane-1,6-dinitrile (Perfluorohexane-1,6-dinitrile), wherein the perfluoro trinitrile-based compound of Formula 3 is 3-cyano difluoro methyl-2,2,3,4,4-pentafluoro pentane di Nitrile (3- (cyano difluoro methyl) -2,2,3,4,4-penta fluoro pentane dinitrile), wherein the perfluoro tetranitrile-based compound of Formula 4 is 3,3-biscyano difluoro Chloromethyl-2,2,4,4-tetrafluoropentane dinitrile (3,3-bis (cyano difluoromethyl) -2,2,4,4-tetra fluoro pentane dinitrile).
특히, 상기 퍼플루오로헥산-1,6-디니트릴은 헥산-1,6-디니트릴(hexane-1,6-dinitrile)과 함께 사용될 수 있다. 상기 퍼플루오로헥산-1,6-디니트릴과 상기 헥산-1,6-디니트릴을 함께 사용하는 경우 리튬 이차 전지의 전지 특성, 특히 고전압 수명 특성 및 저장 특성을 더욱 향상시킬 수 있을 뿐만 아니라, 회복 용량 및 스웰링 특성이 더욱 향상되는 상승 효과를 얻을 수 있다.In particular, the perfluorohexane-1,6-dinitrile may be used with hexane-1,6-dinitrile (hexane-1,6-dinitrile). When the perfluorohexane-1,6-dinitrile and the hexane-1,6-dinitrile are used together, battery characteristics, in particular, high voltage life characteristics and storage characteristics of a lithium secondary battery may be further improved. A synergistic effect can be obtained in which recovery capacity and swelling characteristics are further improved.
이때, 상기 헥산-1,6-디니트릴은 상기 퍼플루오로헥산-1,6-디니트릴 100 중량부에 대하여 1 내지 80 중량부로 포함될 수 있고, 구체적으로 5 내지 70 중량부로 포함될 수 있고, 더욱 구체적으로 8 내지 50 중량부로 포함될 수 있다. 상기 헥산-1,6-디니트릴의 함량이 상기 퍼플루오로헥산-1,6-디니트릴 100 중량부에 대하여 1 중량부 미만이면 방전시 양극에 충분한 전자를 공급하지 못해 상기 상승 효과가 발생하지 않을 수 있고, 80 중량부를 초과하면 양극에 두꺼운 피막을 형성해 저항이 크게 발생할 수도 있다.In this case, the hexane-1,6-dinitrile may be included in an amount of 1 to 80 parts by weight, specifically, 5 to 70 parts by weight, and more, based on 100 parts by weight of the perfluorohexane-1,6-dinitrile. Specifically, it may be included in an amount of 8 to 50 parts by weight. When the content of the hexane-1,6-dinitrile is less than 1 part by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile, the synergistic effect may not occur because sufficient electrons are not supplied to the positive electrode during discharge. If it is more than 80 parts by weight, a thick film may be formed on the anode, thereby greatly increasing resistance.
상기 화학식 1 내지 4의 퍼플루오로 니트릴 화합물을 포함하는 전해질 첨가제는, 전해질 총 중량에 대하여 0.1 내지 10 중량%로 포함될 수 있고, 바람직하게는 0.2 내지 7 중량%로 포함될 수 있고, 보다 바람직하게는 0.5 내지 5 중량%로 포함될 수 있다. The electrolyte additive including the perfluoronitrile compound of Chemical Formulas 1 to 4 may be included in an amount of 0.1 to 10% by weight, preferably 0.2 to 7% by weight, and more preferably, based on the total weight of the electrolyte. 0.5 to 5% by weight may be included.
상기 전해질 첨가제가 0.1 중량% 미만이면 방전시 양극에 충분한 전자를 공급하지 못해 효과가 없을 수 있고 10 중량% 초과하면 양극에 두꺼운 피막을 형성해 저항이 크게 발생할 수 있다.If the electrolyte additive is less than 0.1% by weight, there may be no effect due to insufficient supply of electrons to the positive electrode during discharging. If the electrolyte additive is more than 10% by weight, a thick film may be formed on the positive electrode to greatly increase resistance.
상기 퍼플루오로 니트릴 화합물은 전해질 첨가제로 사용시 리튬 이차 전지의 전지 특성, 특히 수명 특성 및 저저항 특성을 향상시킬 수 있다. The perfluoro nitrile compound may improve battery characteristics, particularly life characteristics and low resistance characteristics of a lithium secondary battery when used as an electrolyte additive.
상기 전해질은 상기한 전해질 첨가제 이외에 유기 용매 및 리튬염을 더 포함할 수 있다.The electrolyte may further include an organic solvent and a lithium salt in addition to the electrolyte additive described above.
상기 유기 용매로는 전지의 전기화학적 반응에 관여하는 이온들이 이동할 수 있는 매질 역할을 할 수 있는 것이라면 특별한 제한없이 사용할 수 있다. 구체적으로 상기 유기 용매로는 에스테르 용매, 에테르 용매, 케톤 용매, 방향족 탄화수소 용매, 알콕시알칸 용매, 카보네이트 용매 등을 사용할 수 있으며, 이들 중 1종 단독으로 또는 2종 이상을 혼합하여 사용할 수 있다.The organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may be an ester solvent, an ether solvent, a ketone solvent, an aromatic hydrocarbon solvent, an alkoxyalkane solvent, a carbonate solvent, or the like, and may be used alone or in combination of two or more thereof.
상기 에스테르 용매의 구체적인 예로는 메틸 아세테이트(methyl acetate), 에틸 아세테이트(ethyl acetate), n-프로필 아세테이트(n-propyl acetate), 디메틸아세테이트(dimethyl acetate), 메틸프로피오네이트(methyl propionate), 에틸프로피오네이트(ethyl propionate), γ-부티로락톤(γ-butyrolactone), 데카놀라이드(decanolide), γ-발레로락톤(γ-valerolactone), 메발로노락톤(mevalonolactone), γ-카프로락톤(γ-caprolactone), δ-발레로락톤(δ-valerolactone), 또는 ε-카프로락톤(ε-caprolactone) 등을 들 수 있다. Specific examples of the ester solvent include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, dimethyl acetate, methyl propionate, and ethyl prop. Cypionate (ethyl propionate), γ-butyrolactone, decanolide, γ-valerolactone, mevalonolactone, γ-caprolactone -caprolactone), δ-valerolactone, ε-caprolactone and the like.
상기 에테르계 용매의 구체적인 예로는 디부틸 에테르(dibutyl ether), 테트라글라임(tetraglyme), 2-메틸테트라히드로퓨란(2-methyltetrahydrofuran), 또는 테트라히드로퓨란(tetrahydrofuran) 등을 들 수 있다. Specific examples of the ether solvents include dibutyl ether, tetraglyme, 2-methyltetrahydrofuran, tetrahydrofuran, and the like.
상기 케톤계 용매의 구체적인 예로는 시클로헥사논(cyclohexanone) 등을 들 수 있다. 상기 방향족 탄화수소계 유기 용매의 구체적인 예로는 벤젠(benzene), 플루오로벤젠(fluorobenzene), 클로로벤젠(chlorobenzene), 아이오도벤젠(iodobenzene), 톨루엔(toluene), 플루오로톨루엔(fluorotoluene), 또는 자일렌(xylene) 등을 들 수 있다. 상기 알콕시알칸 용매로는 디메톡시에탄(dimethoxy ethane) 또는 디에톡시에탄(diethoxy ethane) 등을 들 수 있다.Specific examples of the ketone solvent include cyclohexanone. Specific examples of the aromatic hydrocarbon-based organic solvent are benzene, fluorobenzene, chlorobenzene, iodobenzene, toluene, fluorotoluene, or xylene (xylene) etc. are mentioned. Examples of the alkoxyalkane solvent include dimethoxy ethane or diethoxy ethane.
상기 카보네이트 용매의 구체적인 예로는 디메틸카보네이트(dimethylcarbonate, DMC), 디에틸카보네이트(diethylcarbonate, DEC), 디프로필카보네이트(dipropylcarbonate, DPC), 메틸프로필카보네이트(methylpropylcarbonate, MPC), 에틸프로필카보네이트(ethylpropylcarbonate, EPC), 메틸에틸카보네이트(methylethylcarbonate, MEC), 에틸메틸카보네이트(ethylmethylcarbonate, EMC), 에틸렌카보네이트(ethylene carbonate, EC), 프로필렌카보네이트(propylene carbonate, PC), 부틸렌카보네이트(butylenes carbonate, BC), 또는 플루오로에틸렌카보네이트(fluoroethylene carbonate, FEC) 등을 들 수 있다. Specific examples of the carbonate solvent include dimethyl carbonate (dimethyl carbonate, DMC), diethyl carbonate (DEC), dipropyl carbonate (dipropyl carbonate, DPC), methyl propyl carbonate (methyl propyl carbonate, MPC), ethyl propyl carbonate (ethyl propyl carbonate, EPC) , Methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or fluoro Ethylene carbonate (FEC) etc. are mentioned.
이중에서도 상기 유기 용매로 카보네이트계 용매를 사용하는 것이 바람직하며, 상기 카보네이트계 용매 중에서도 보다 바람직하게는 전지의 충방전 성능을 높일 수 있는 높은 이온전도도를 갖는 고유전율의 카보네이트계 유기 용매와, 상기 고유전율의 유기 용매의 점도를 적절하게 조절할 수 있는 점도가 낮은 카보네이트계 유기 용매를 혼합하여 사용하는 것이 바람직할 수 있다. 구체적으로 에틸렌카보네이트, 프로필렌카보네이트 및 이들의 혼합물로 이루어진 군에서 선택되는 고유전율의 유기 용매와, 에틸메틸카보네이트, 디메틸카보네이트, 디에틸카보네이트 및 이들의 혼합물로 이루어진 군에서 선택되는 저점도의 유기 용매를 혼합하여 사용할 수 있다. 보다 더 바람직하게는 상기 고유전율의 유기 용매와 저점도의 유기 용매를 2:8 내지 8:2의 부피비로 혼합하여 사용하는 것이 좋으며, 보다 구체적으로 에틸렌카보네이트 또는 프로필렌카보네이트; 에틸메틸카보네이트; 그리고 디메틸카보네이트 또는 디에틸카보네이트를 5:1:1 내지 2:5:3의 부피비로 혼합하여 사용할 수 있으며, 바람직하게는 3:5:2의 부피비로 혼합하여 사용할 수 있다.Among them, a carbonate solvent is preferably used as the organic solvent, and among the carbonate solvents, a carbonate organic solvent having a high dielectric constant having a high ionic conductivity that can increase the charge / discharge performance of a battery, and the intrinsic It may be preferable to use a mixture of a low-viscosity carbonate-based organic solvent capable of appropriately adjusting the viscosity of the organic solvent. Specifically, an organic solvent having a high dielectric constant selected from the group consisting of ethylene carbonate, propylene carbonate and mixtures thereof, and an organic solvent having a low viscosity selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate and mixtures thereof It can be mixed and used. More preferably, the high dielectric constant organic solvent and the low viscosity organic solvent may be mixed and used in a volume ratio of 2: 8 to 8: 2, and more specifically, ethylene carbonate or propylene carbonate; Ethyl methyl carbonate; And dimethyl carbonate or diethyl carbonate can be used by mixing in a volume ratio of 5: 1: 1 to 2: 5: 3, preferably can be used by mixing in a volume ratio of 3: 5: 2.
상기 리튬염은 리튬 이차 전지에서 사용되는 리튬 이온을 제공할 수 있는 화합물이라면 특별한 제한없이 사용할 수 있다. 구체적으로 상기 리튬염으로는 LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiN(CaF2a + 1SO2)(CbF2b + 1SO2)(단, a 및 b는 자연수, 바람직하게는 1≤a≤20이고, 1≤b≤20임), LiCl, LiI, LiB(C2O4)2 및 이들의 혼합물로 이루어진 군에서 선택되는 것을 사용할 수 있으며, 바람직하게 리튬 헥사플루오로포스페이트(LiPF6)을 사용하는 것이 좋다.The lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt is LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (C 2 F 5 SO 3 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , LiN (C a F 2a + 1 SO 2 ) (C b F 2b + 1 SO 2 ) (where a and b are natural numbers , Preferably 1 ≦ a ≦ 20, and 1 ≦ b ≦ 20), LiCl, LiI, LiB (C 2 O 4 ) 2, and mixtures thereof may be used, preferably lithium hexa It is preferable to use fluorophosphate (LiPF 6 ).
상기 리튬염을 전해질에 용해시키면, 상기 리튬염은 리튬 이차 전지 내에서 리튬 이온의 공급원으로 기능하고, 양극과 음극 간의 리튬 이온의 이동을 촉진할 수 있다. 이에 따라, 상기 리튬염은 상기 전해질 내에 대략 0.6M 내지 2M의 농도로 포함되는 것이 바람직하다. 상기 리튬염의 농도가 0.6M 미만인 경우 전해질의 전도도가 낮아져 전해질 성능이 떨어질 수 있고, 2M를 초과하는 경우 전해질의 점도가 증가하여 리튬 이온의 이동성이 낮아질 수 있다. 이와 같은 전해질의 전도도 및 리튬 이온의 이동성을 고려하면, 상기 리튬염은 상기 전해질 내에서 대략 0.7M 내지 1.6M로 조절되는 것이 보다 바람직할 수 있다.When the lithium salt is dissolved in an electrolyte, the lithium salt may function as a source of lithium ions in the lithium secondary battery and may promote the movement of lithium ions between the positive electrode and the negative electrode. Accordingly, the lithium salt is preferably contained at a concentration of approximately 0.6M to 2M in the electrolyte. When the concentration of the lithium salt is less than 0.6M, the conductivity of the electrolyte may be lowered and the performance of the electrolyte may be lowered. When the concentration of the lithium salt is higher than 2M, the viscosity of the electrolyte may be increased, thereby reducing the mobility of lithium ions. In consideration of the conductivity of the electrolyte and the mobility of the lithium ions, the lithium salt may be more preferably adjusted to about 0.7M to 1.6M in the electrolyte.
상기 전해질은 상기 전해질 구성 성분들 외에도 전지의 수명특성 향상, 전지 용량 감소 억제, 전지의 방전 용량 향상 등을 목적으로 일반적으로 전해질에 사용될 수 있는 첨가제(이하, 기타 첨가제라 함)를 더 포함할 수 있다.In addition to the electrolyte components, the electrolyte may further include additives (hereinafter, referred to as other additives) that can be generally used in the electrolyte for the purpose of improving the life characteristics of the battery, suppressing the reduction of the battery capacity, and improving the discharge capacity of the battery. have.
상기 기타 첨가제의 구체적인 예로는 비닐렌카보네이트(vinylenecarbonate, VC), 메탈플루오라이드(metal fluoride, 예를 들면, LiF, RbF, TiF, AgF, AgF2, BaF2, CaF2, CdF2, FeF2, HgF2, Hg2F2, MnF2, NiF2, PbF2, SnF2, SrF2, XeF2, ZnF2, AlF3, BF3, BiF3, CeF3, CrF3, DyF3, EuF3, GaF3, GdF3, FeF3, HoF3, InF3, LaF3, LuF3, MnF3, NdF3, PrF3, SbF3, ScF3, SmF3, TbF3, TiF3, TmF3, YF3, YbF3, TIF3, CeF4, GeF4, HfF4, SiF4, SnF4, TiF4, VF4, ZrF44, NbF5, SbF5, TaF5, BiF5, MoF6, ReF6, SF6, WF6, CoF2, CoF3, CrF2, CsF, ErF3, PF3, PbF3, PbF4, ThF4, TaF5, SeF6 등), 글루타노니트릴(glutaronitrile, GN), 숙시노니트릴(succinonitrile, SN), 아디포니트릴(adiponitrile, AN), 4-톨루니트릴(4-tolunitrile), 1,3,6-헥산트리카보니트릴(1,3,6-hexanetricarbonitrile), 프로필렌설파이드(propylene sulfide, PS), 3,3'-티오디프로피오니트릴(3,3'-thiodipropionitrile, TPN), 비닐에틸렌카보네이트(vinylethylene carbonate, VEC), 플루오로에틸렌카보네이트(fluoroethylene carbonate, FEC), 디플루오로에틸렌카보네이트(difluoroethylenecarbonate), 플루오로디메틸카보네이트(fluorodimethylcarbonate), 플루오로에틸메틸카보네이트(fluoroethylmethylcarbonate), 리튬비스(트리플루오로메틸설포닐)이미드(lithium bis(trifluoromethylsulfonyl)imide, LiTFSI), 리튬 테트라플루오로보레이트(lithium tetrafluoroborate, LiBF4), 리튬비스(옥살레이토)보레이트(lithium bis(oxalato)borate, LiBOB), 리튬 디플루오로(옥살레이토) 보레이트(lithium difluoro(oxalato)borate, LiDFOB), 리튬(말로네이토 옥살레이토)보레이트(lithium (malonato oxalato) borate, LiMOB), 리튬 디플루오로포스페이트(lithium difluorophosphate, LiPO2F2), LiPF2C4O8, LiSO3CF3, LiPF4(C2O4), LiP(C2O4)3, LiC(SO2CF3)3, LiBF3(CF3CF2), LiPF3(CF3CF2)3, Li2B12F12, 1,3-프로판설톤(1,3-propane sultone), 1,3-프로펜설톤(1,3-propene sultone), 바이페닐(biphenayl), 시클로헥실벤젠(cyclohexyl benzene), 4-플루오로톨루엔(4-fluorotoluene), 숙시노언하이드라이드(succinic anhydride), 에틸렌설페이트언하이드라이드(ethylene sulfate anhydride), 트리스(트리메틸실릴)보레이트(tris(methylsilyl)borate) 등을 들 수 있으며, 이들 중 1종 단독으로 또는 2종 이상을 혼합하여 포함할 수 있다.Examples of the other additives include vinylene carbonate (vinylenecarbonate, VC), metal fluoride (metal fluoride, for example, LiF, RbF, TiF, AgF , AgF 2, BaF 2, CaF 2, CdF 2, FeF 2, HgF 2 , Hg 2 F 2 , MnF 2 , NiF 2 , PbF 2 , SnF 2 , SrF 2 , XeF 2 , ZnF 2 , AlF 3 , BF 3 , BiF 3 , CeF 3 , CrF 3 , DyF 3 , EuF 3 , GaF 3, GdF 3, FeF 3 , HoF 3, InF 3, LaF 3, LuF 3, MnF 3, NdF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF 3, TmF 3, YF 3 , YbF 3, TIF 3, CeF 4, GeF 4, HfF 4, SiF 4, SnF 4, TiF 4, VF 4, ZrF4 4, NbF 5, SbF 5, TaF 5, BiF 5, MoF 6, ReF 6, SF 6 , WF 6 , CoF 2 , CoF 3 , CrF 2 , CsF, ErF 3 , PF 3 , PbF 3 , PbF 4 , ThF 4 , TaF 5 , SeF 6, etc.), glutanonitrile (GN), aging Succinonitrile (SN), adiponitrile (AN), 4-tolunitrile (4-tolunitrile), 1,3,6-hexanetricarbonitrile (1,3,6-hexanetricarbonitrile), propylene sulfide (propylene sulfide, PS), 3,3'-thiodipro Onitrile (3,3'-thiodipropionitrile (TPN), vinylethylene carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylenecarbonate, fluorodimethylcarbonate , Fluoroethylmethylcarbonate, lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium tetrafluoroborate (LiBF 4 ), Lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (lithium difluoro (oxalato) borate (LiDFOB), lithium (malonato oxalato) borate (lithium (both) malonato oxalato borate (LiMOB), lithium difluorophosphate (Lithium difluorophosphate, LiPO 2 F 2 ), LiPF 2 C 4 O 8 , LiSO 3 CF 3 , LiPF 4 (C 2 O 4 ), LiP (C 2 O 4 ) 3 , LiC (SO 2 CF 3 ) 3 , LiBF 3 (CF 3 CF 2 ), LiPF 3 (CF 3 CF 2 ) 3 , Li 2 B 12 F 12 , 1,3-propanesultone (1,3-propane sultone, 1,3-propene sultone, biphenayl, cyclohexyl benzene, 4-fluorotoluene, succinoanhydride ( succinic anhydride), ethylene sulfate anhydride, tris (methylsilyl) borate, and the like, which may be included alone or in combination of two or more thereof. have.
상기 기타 첨가제는 전해질 총 중량에 대하여 0.1 내지 20중량%로 포함될 수 있고, 0.2 내지 5중량%로 포함되는 것이 바람직하다.The other additives may be included in 0.1 to 20% by weight relative to the total weight of the electrolyte, it is preferable to include 0.2 to 5% by weight.
본 발명의 다른 일 실시예에 따르면 상기 전해질을 포함하는 리튬 이차 전지를 제공한다. 본 발명의 실시예에 따른 리튬 이차 전지는 사용하는 세퍼레이터와 전해질의 종류에 따라 리튬 이온 전지, 리튬 이온 폴리머 전지 및 리튬 폴리머 전지로 분류될 수 있고, 형태에 따라 원통형, 각형, 코인형, 파우치형 등으로 분류될 수 있으며, 사이즈에 따라 벌크 타입과 박막 타입으로 나눌 수 있다. 본 발명의 실시예에 따른 전해질은 이중에서도 리튬 이온 전지, 알루미늄 적층 전지 및 리튬 폴리머 전지에 적용하기에 특히 우수할 수 있다.According to another embodiment of the present invention provides a lithium secondary battery including the electrolyte. Lithium secondary battery according to an embodiment of the present invention can be classified into a lithium ion battery, a lithium ion polymer battery and a lithium polymer battery according to the type of separator and electrolyte used, cylindrical, square, coin type, pouch type depending on the form Etc., and may be classified into a bulk type and a thin film type according to the size. The electrolyte according to the embodiment of the present invention may be particularly excellent for application to a lithium ion battery, an aluminum laminated battery and a lithium polymer battery.
상세하게는 상기 리튬 이차 전지는 서로 대향 배치되는 양극 활물질을 포함하는 양극과 음극 활물질을 포함하는 음극, 그리고 상기 양극과 음극 사이에 개재되는 상기 전해질을 포함한다.In detail, the lithium secondary battery includes a positive electrode including a positive electrode active material disposed opposite to each other, a negative electrode including a negative electrode active material, and the electrolyte interposed between the positive electrode and the negative electrode.
도 1은 본 발명의 일 실시예에 따른 리튬 이차 전지(1)의 분해 사시도이다. 도 1을 참조하면, 본 발명의 또 다른 일 실시예에 따른 리튬 이차 전지(1)는 음극(3), 양극(5), 상기 음극(3) 및 양극(5) 사이에 세퍼레이터(7)를 배치하여 전극 조립체(9)를 제조하고, 이를 케이스(15)에 위치시키고 비수 전해질을 주입하여 상기 음극(3), 상기 양극(5) 및 상기 세퍼레이터(7)가 전해질에 함침되도록 함으로써 제조할 수 있다. 1 is an exploded perspective view of a lithium secondary battery 1 according to an embodiment of the present invention. Referring to FIG. 1, a lithium secondary battery 1 according to another embodiment of the present invention includes a separator 7 between a negative electrode 3, a positive electrode 5, the negative electrode 3, and a positive electrode 5. By placing the electrode assembly 9, placing it in the case 15, and injecting a nonaqueous electrolyte so that the cathode 3, the anode 5, and the separator 7 are impregnated with the electrolyte. have.
상기 음극(3) 및 양극(5)에는 전지 작용시 발생하는 전류를 집전하기 위한 도전성 리드 부재(10, 13)가 각기 부착될 수 있고, 상기 리드 부재(10, 13)는 각각 양극(5) 및 음극(3)에서 발생한 전류를 양극 및 음극 단자로 유도할 수 있다. Conductive lead members 10 and 13 may be attached to the negative electrode 3 and the positive electrode 5, respectively, and the lead members 10 and 13 may be attached to the positive electrode 5, respectively. And current generated at the cathode 3 to the anode and cathode terminals.
상기 양극(5)은 양극 활물질, 도전제 및 바인더를 혼합하여 양극 활물질 층 형성용 조성물을 제조한 후, 상기 양극 활물질 층 형성용 조성물을 알루미늄 포일 등의 양극 전류 집전체에 도포한 후 압연하여 제조할 수 있다.The positive electrode 5 is prepared by mixing a positive electrode active material, a conductive agent and a binder to prepare a composition for forming a positive electrode active material layer, and then applying the composition for forming a positive electrode active material layer to a positive electrode current collector such as aluminum foil and rolling the same. can do.
상기 양극 활물질로는 리튬의 가역적인 인터칼레이션 및 디인터칼레이션이 가능한 화합물(리티에이티드 인터칼레이션 화합물)을 사용할 수 있다. 구체적으로는 하기 화학식 5로 표시되는 올리빈형 리튬 금속 화합물을 사용할 수 있다.As the cathode active material, a compound (lithiated intercalation compound) capable of reversible intercalation and deintercalation of lithium may be used. Specifically, the olivine-type lithium metal compound represented by the following formula (5) can be used.
[화학식 5][Formula 5]
LixMyM'zXO4-wYw Li x M y M ' z XO 4-w Y w
(상기 화학식 5에서, 상기 M 및 M'은 각각 독립적으로 Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B 및 이들의 조합으로 이루어진 군에서 선택되는 원소이고, 상기 X는 P, As, Bi, Sb, Mo 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, 상기 Y는 F, S 및 이들의 조합으로 이루어진 군에서 선택되는 원소이고, 0<x≤1, 0<y≤1, 0<z≤1, 0<x+y+z≤2이고, 0≤w≤0.5이다.)(In Formula 5, M and M 'are each independently Fe, Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Mo, Ti, Zn, Al, Ga, Mg, B and combinations thereof It is an element selected from the group consisting of, wherein X is an element selected from the group consisting of P, As, Bi, Sb, Mo and combinations thereof, wherein Y is selected from the group consisting of F, S and combinations thereof Element, 0 <x≤1, 0 <y≤1, 0 <z≤1, 0 <x + y + z≤2, and 0≤w≤0.5.)
상기 화합물 중에서도 전지의 용량 특성 및 안정성을 높일 수 있다는 점에서 LiCoO2, LiMnO2, LiMn2O4, LiNiO2, LiNixMn(1-x)O2(단, 0<x<1), LiMlxM2yO2(단, 0≤x≤1, 0≤y≤1, 0≤x+y≤1, M1 및 M2은 각각 독립적으로 Al, Sr, Mg 및 La로 이루어진 군에서 선택된 어느 하나이다) 및 이들의 혼합물로 이루어진 군에서 선택되는 것을 사용하는 것이 바람직할 수 있다.Among the above compounds, LiCoO 2 , LiMnO 2 , LiMn 2 O 4 , LiNiO 2 , LiNi x Mn (1-x) O 2 (where 0 <x <1) and LiM can improve the capacity characteristics and stability of the battery. lx M 2y O 2 (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1, M 1 and M 2 are each independently selected from the group consisting of Al, Sr, Mg and La) One), and mixtures thereof.
상기 음극(3)은 상기 양극(5)과 마찬가지로 음극 활물질, 바인더 및 선택적으로 도전제를 혼합하여 음극 활물질 층 형성용 조성물을 제조한 후, 이를 구리 포일 등의 음극 전류 집전체에 도포하여 제조할 수 있다.The negative electrode 3 is prepared by mixing a negative electrode active material, a binder, and optionally a conductive agent similarly to the positive electrode 5 to prepare a composition for forming a negative electrode active material layer, and then applying the same to a negative electrode current collector such as copper foil. Can be.
상기 음극 활물질로는 리튬의 가역적인 인터칼레이션 및 디인터칼레이션이 가능한 화합물을 사용할 수 있다. 상기 음극 활물질의 구체적인 예로는 인조흑연, 천연흑연, 흑연화 탄소섬유, 비정질탄소 등의 탄소질 재료를 사용할 수 있다. 또한, 상기 탄소질 재료 이외에, 리튬과 합금화가 가능한 금속질 화합물, 또는 금속질 화합물과 탄소질 재료를 포함하는 복합물도 음극 활물질로 사용할 수 있다.As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples of the negative electrode active material may be a carbonaceous material such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, or the like. In addition to the carbonaceous material, a metallic compound capable of alloying with lithium, or a composite including a metallic compound and a carbonaceous material may also be used as the negative electrode active material.
상기 리튬과 합금화가 가능한 금속으로는, Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si합금, Sn합금 그리고 Al합금 중 적어도 어느 하나가 사용될 수 있다. 또한, 상기 음극 활물질로서 금속 리튬 박막을 사용할 수도 있다.As the metal capable of alloying with lithium, at least one of Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, and Al alloy may be used. In addition, a metal lithium thin film may be used as the negative electrode active material.
상기 음극 활물질로는 안정성이 높다는 면에서 결정질 탄소, 비결정질 탄소, 탄소 복합체, 리튬 금속, 리튬을 포함하는 합금 및 이들의 혼합물로 이루어진 군에서 선택된 어느 하나를 사용할 수 있다.As the negative electrode active material, any one selected from the group consisting of crystalline carbon, amorphous carbon, carbon composite, lithium metal, an alloy containing lithium, and mixtures thereof may be used in view of high stability.
한편, 상기 전해질은 앞서 전해질에 관한 부분에서 기재한 바와 같으므로 그 기재를 생략한다. 상기 리튬 이차 전지는 통상의 방법에 의하여 제조될 수 있는 바, 본 명세서에서 상세한 설명은 생략한다. 본 실시예에서는 파우치형 리튬 이차 전지를 예로 들어 설명하였으나, 본 발명의 기술이 파우치형 리튬 이차 전지로 한정되는 것은 아니며, 전지로서 작동할 수 있으면 어떠한 형상으로도 가능할 수 있다.On the other hand, since the electrolyte is as described above in the section on the electrolyte, the description thereof is omitted. The lithium secondary battery may be manufactured by a conventional method, and thus detailed description thereof will be omitted. In the present embodiment, the pouch type lithium secondary battery has been described as an example, but the technology of the present invention is not limited to the pouch type lithium secondary battery, and may be any shape as long as it can operate as a battery.
상술한 바와 같이, 본 발명의 실시예에 따른 전해질을 포함하는 리튬 이차 전지는 낮은 DC-IR 특성, 높은 고온 저장 특성, 그리고 향상된 출력 특성을 발휘할 수 있어, 빠른 충전 속도가 요구되는 휴대전화, 노트북 컴퓨터, 디지털 카메라, 캠코더 등의 휴대용 기기나, 하이브리드 전기자동차(hybrid electric vehicle, HEV), 플러그인 하이브리드 전기자동차(plug-in HEV, PHEV) 등의 전기 자동차 분야, 그리고 중대형 에너지 저장 시스템에 유용할 수 있다.As described above, the lithium secondary battery including the electrolyte according to the embodiment of the present invention can exhibit low DC-IR characteristics, high high temperature storage characteristics, and improved output characteristics, so that a fast charging speed is required for mobile phones and laptops. It can be useful in portable devices such as computers, digital cameras and camcorders, in the field of electric vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and medium and large energy storage systems. have.
이하, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 용이하게 실시할 수 있도록 본 발명의 실시예에 대하여 상세히 설명한다. 그러나 본 발명은 여러 가지 상이한 형태로 구현될 수 있으며 여기에서 설명하는 실시예에 한정되지 않는다. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.
[제조예: 전해액 및 리튬이차전지의 제조]Preparation Example: Preparation of Electrolyte and Lithium Secondary Battery
하기에서, 양극으로는 양극 활물질로 LiCoO2, 도전제로 카본블랙(carbon black), 바인더로 폴리비닐리덴 플루오라이드(polyvinylidene fluoride, PVDF), 용매로 n-메틸-2-피롤리돈(n-methyl-2-pyrrolidone, NMP)를 혼합하여 제조한 슬러리를 알루미늄(Al) 기재에 코팅하여 제조한 것을 사용하였다. 또한, 음극으로는 인조흑연인 MCMB(mesocarbon microbead)와 카본블랙(carbon black), 바인더로 PVDF를, 용매로는 NMP를 혼합하여 제조한 슬러리를 구리(Cu) 기재에 코팅하여 제조한 것을 사용하였다.In the following, LiCoO 2 as a positive electrode active material, carbon black as a conductive material, polyvinylidene fluoride (PVDF) as a binder, n-methyl-2-pyrrolidone (n-methyl as a solvent) The slurry prepared by mixing -2-pyrrolidone (NMP) was coated on an aluminum (Al) substrate. In addition, as a negative electrode, a slurry prepared by mixing artificial graphite MCMB (mesocarbon microbead), carbon black (carbon black), PVDF as a binder, and NMP as a solvent was coated on a copper (Cu) substrate. .
(실시예 1)(Example 1)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 퍼플루오로 펜테인 니트릴(Perfluoropentanenitrile) 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1 wt% of Perfluoropentanenitrile as an electrolyte solution additive with respect to the total weight of the mixed solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(실시예 2)(Example 2)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile) 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1% by weight of perfluorohexane-1,6-dinitrile as an electrolyte solution additive with respect to the total weight of the mixed solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(실시예 3)(Example 3)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 3-시아노디플루오로메틸-2,2,3,4,4-펜타르루오로펜테인디니트릴(3-(cyanodifluoromethyl)-2,2,3,4,4-pentafluoropentanedinitrile) 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, 3-cyanodifluoromethyl-2,2,3,4,4-pentaruropentanedinitrile (3- (cyanodifluoromethyl) -2,2,3,4,4- as an electrolyte additive with respect to the total weight of the mixed solution 1% by weight of pentafluoropentanedinitrile) was added to prepare an electrolyte solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(실시예 4)(Example 4)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 3,3-비스시아노디플루오로메틸-2,2,4,4-테트라플루오로펜테인디니트릴(3,3-bis(cyanodifluoromethyl)-2,2,4,4-tetrafluoropentanedinitrile) 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, 3,3-biscyanodifluoromethyl-2,2,4,4-tetrafluoropentanedinitrile (3,3-bis (cyanodifluoromethyl) -2,2,4, as an electrolyte additive with respect to the total weight of the mixed solution 1 wt% of 4-tetrafluoropentanedinitrile) was added to the electrolyte solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(실시예 5)(Example 5)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile) 0.8 중량% 및 헥산-1,6-디니트릴(hexane-1,6-dinitrile) 0.2 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, 0.8 wt% of Perfluorohexane-1,6-dinitrile and hexane-1,6-dinitrile as the electrolyte additive based on the total weight of the mixed solution 0.2 wt% was added to prepare an electrolyte solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(비교예 1)(Comparative Example 1)
에틸렌카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 화학식 1에서 일부만 불소로 치환된 화합물 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in Formula 1 as an electrolyte solution additive with respect to the total weight of the mixed solution. A lithium secondary battery in the form of an aluminum pouch was manufactured using the prepared electrolyte and the positive electrode and negative electrode prepared above.
(비교예 2)(Comparative Example 2)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 화학식 2에서 일부만 불소로 치환된 화합물 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in Formula 2 as an electrolyte solution additive with respect to the total weight of the mixed solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(비교예 3)(Comparative Example 3)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 화학식 3에서 일부만 불소로 치환된 화합물 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in Formula 3 as an electrolyte solution additive with respect to the total weight of the mixed solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(비교예 4)(Comparative Example 4)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 화학식 4에서 일부만 불소로 치환된 화합물 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1 wt% of a compound partially substituted with fluorine in the general formula (4) as an electrolyte solution additive with respect to the total weight of the mixed solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
(비교예 5)(Comparative Example 5)
에틸렌 카보네이트(EC), 에틸메틸카보네이트(EMC), 그리고 디메틸카보네이트(DEC)의 혼합용액(부피비: EC/EMC/DEC = 3/5/2)에 LiPF6 1.15M이 되도록 첨가한 후, 수득된 혼합용액 총 중량에 대하여 전해액 첨가제로서 헥산-1,6-디니트릴 (hexane-1,6-dinitrile) 1 중량%를 첨가하여 전해액을 제조하였다. 상기 제조된 전해액과 앞서 제조해둔 양극 및 음극을 이용하여 알루미늄 파우치 형태(Al-pouch type)의 리튬 이차 전지를 제조하였다.To a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio: EC / EMC / DEC = 3/5/2) to be LiPF 6 1.15 M, An electrolyte solution was prepared by adding 1% by weight of hexane-1,6-dinitrile as an electrolyte additive with respect to the total weight of the mixed solution. An aluminum pouch type lithium secondary battery was manufactured using the prepared electrolyte solution and the cathode and anode prepared in advance.
[실험예 1: 리튬 이차 전지의 용량 평가]Experimental Example 1: Capacity Evaluation of a Lithium Secondary Battery
상기 비교예 1 내지 비교예 5 및 실시예 1 내지 실시예 5에서 제작된 전지를 각각 1.0C-CCCV-4.45V, 0.04C로 충전하고 10 분 휴식 후 1.0C-CC-3.0V가 될 때까지 방전시키고, 10 분 휴식하였다. 상기 사이클을 300 회 반복하면서 효율을 측정하여 표 1에 나타내었다. 또한, 실시예 2, 비교예 2 및 비교예 5의 데이터를 도 2에 나타내었다.The batteries prepared in Comparative Examples 1 to 5 and Examples 1 to 5 were charged with 1.0C-CCCV-4.45V and 0.04C, respectively, and rested for 10 minutes until they reached 1.0C-CC-3.0V. Discharged and rested for 10 minutes. The efficiency is measured while repeating the cycle 300 times and is shown in Table 1. Moreover, the data of Example 2, the comparative example 2, and the comparative example 5 are shown in FIG.
전해액 조성Electrolyte composition 1cycle 방전용량(mAh)1cycle discharge capacity (mAh) 200cycle 방전용량(mAh)200cycle discharge capacity (mAh) 효율(%)efficiency(%)
비교예1(화학식1 일부만 F로치환)Comparative Example 1 (Some of Formula 1 Substituted with F) 840.7840.7 336336 40.140.1
비교예2(화학식2 일부만 F로치환)Comparative Example 2 (Part of Formula 2 substituted with F) 841.1841.1 339.4339.4 40.440.4
비교예3(화학식3 일부만 F로치환)Comparative Example 3 (Formula 3 partially substituted with F) 840.8840.8 339.6339.6 40.440.4
비교예4(화학식4 일부만 F로치환)Comparative Example 4 (Formula 4 partially substituted with F) 840.1840.1 338.6338.6 40.340.3
비교예5(헥산-1,6-디니트릴)Comparative Example 5 (hexane-1,6-dinitrile) 841.1841.1 339.4339.4 40.440.4
실시예1(화학식1)Example 1 (Formula 1) 841.3841.3 696.6696.6 82.882.8
실시예2(화학식2)Example 2 (Formula 2) 840.9840.9 697.2697.2 83.183.1
실시예3(화학식3)Example 3 840.8840.8 696.2696.2 82.882.8
실시예4(화학식4)Example 4 841.2841.2 696.1696.1 83.083.0
실시예5(화학식2+ 헥산-1,6-디니트릴)Example 5 (Formula 2+ Hexane-1,6-Dinitrile) 841.3841.3 696.6696.6 82.882.8
상기 표 1 및 도 2를 참고하면, 고전압으로 충/방전 하였을 때, 비교예의 효율은 절반 이상 감소하였으나, 본 발명에 다른 전해질을 사용한 실시예는 비교예 보다 2배 높은 효율을 나타내었다. Referring to Table 1 and FIG. 2, when charged / discharged at a high voltage, the efficiency of the comparative example was reduced by more than half, but the example using another electrolyte in the present invention showed twice the efficiency than the comparative example.
그 결과 본 발명은 리튬 이차 전지의 전지 특성, 특히 고전압에서의 양극 피막 형성 특성 및 전지 내 저항 특성을 향상시킬 수 있다는 것을 확인할 수 있었다.As a result, it was confirmed that the present invention can improve the battery characteristics of the lithium secondary battery, in particular, the positive electrode film formation characteristic and the resistance resistance in the battery at high voltage.
[[ 실험예Experimental Example 2: 리튬 이차 전지의 저장 평가] 2: storage evaluation of lithium secondary battery]
상기 실시예 2, 실시예 5 및 비교예 2에서 제조된 전지를 4.45V로 충전 후 60℃에서 4주 동안 저장하면서 전지의 남아 있는 방전 용액을 측정하여 회복 용량을 측정하였고, 전지의 부풀림 여부를 측정하여 스웰링(swelling) 특성을 측정하였으며, 그 결과를 각각 하기 표 2 및 표 3에 나타내었다.The battery prepared in Examples 2, 5 and Comparative Example 2 was charged to 4.45V and then stored at 60 ° C. for 4 weeks, and then the remaining discharge solution of the battery was measured to measure the recovery capacity. By measuring the swelling (swelling) characteristics were measured, the results are shown in Table 2 and Table 3, respectively.
비교예 5(mAh)Comparative Example 5 (mAh) 실시예 2(mAh)Example 2 (mAh) 실시예 5(mAh)Example 5 (mAh)
1주차Week 1 691.3691.3 692.7692.7 697.1697.1
2주차2nd week 671.8671.8 682.1682.1 694.2694.2
3추차3 tea 664.2664.2 665.3665.3 688.4688.4
4주차4 weeks 631.2631.2 653.9653.9 674.5674.5
비교예 5(mm)Comparative Example 5 (mm) 실시예 2(mm)Example 2 (mm) 실시예 5(mm)Example 5 (mm)
1주차Week 1 2.842.84 2.842.84 2.652.65
2주차2nd week 2.862.86 2.742.74 2.662.66
3추차3 tea 3.983.98 3.643.64 2.712.71
4주차4 weeks 3.993.99 3.683.68 2.722.72
상기 표 2 및 표 3을 참고하면, 상기 비교예 5에서 사용된 헥산-1,6-디니트릴은 상기 실시예 2에서 사용된 퍼플루오로헥산-1,6-디니트릴에 비하여 회복 용량 및 스웰링 특성이 좋지 않음에도 불구하고, 상기 헥산-1,6-디니트릴과 퍼플루오로헥산-1,6-디니트릴을 혼합하여 사용한 실시예 5의 경우, 상기 퍼플루오로헥산-1,6-디니트릴만을 단독으로 사용한 실시예 2에 비하여 상기 전해액 첨가제의 전체 함량이 동일함에도 불구하고 회복 용량 및 스웰링 특성이 더욱 향상되는 상승 효과를 얻었음을 확인할 수 있다.Referring to Table 2 and Table 3, the hexane-1,6-dinitrile used in Comparative Example 5 is a recovery capacity and swell compared to the perfluorohexane-1,6-dinitrile used in Example 2 In the case of Example 5, in which the hexane-1,6-dinitrile and the perfluorohexane-1,6-dinitrile were mixed in spite of poor ring characteristics, the perfluorohexane-1,6- Compared with Example 2 using only dinitrile alone, even though the total content of the electrolyte additive is the same, it can be seen that a synergistic effect of further improving recovery capacity and swelling characteristics is obtained.
이상에서 본 발명의 바람직한 실시예에 대하여 상세하게 설명하였지만 본 발명의 권리범위는 이에 한정되는 것은 아니고 다음의 청구범위에서 정의하고 있는 본 발명의 기본 개념을 이용한 당업자의 여러 변형 및 개량 형태 또한 본 발명의 권리범위에 속하는 것이다.Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.
[부호의 설명][Description of the code]
1: 리튬 이차 전지1: lithium secondary battery
3: 음극 5: 양극3: cathode 5: anode
7: 세퍼레이터 9: 전극 조립체7: Separator 9: Electrode Assembly
10, 13: 리드 부재 15: 케이스10, 13: lead member 15: case
본 발명은 리튬 이차 전지용 전해질 및 이를 포함하는 리튬 이차 전지에 관한 것으로서, 상기 리튬 이차 전지용 전해질은 리튬 이차 전지의 전지 특성, 특히 고전압에서의 양극 피막 형성 특성 및 전지 내 저항 특성을 향상시킬 수 있다.The present invention relates to an electrolyte for a lithium secondary battery and a lithium secondary battery including the same, wherein the electrolyte for a lithium secondary battery may improve battery characteristics of a lithium secondary battery, in particular, a cathode film formation characteristic and a battery resistance characteristic at high voltage.

Claims (14)

  1. 퍼플루오로 니트릴 화합물(perfluoro nitrile compounds)을 전해질 첨가제로 포함하는 리튬 이차 전지용 전해질.An electrolyte for a lithium secondary battery comprising perfluoro nitrile compounds as an electrolyte additive.
  2. 제1항에 있어서, The method of claim 1,
    상기 퍼플루오로 니트릴 화합물은 퍼플루오로 모노니트릴 화합물, 퍼플루오로 디니트릴 화합물, 퍼플루오로 트리니트릴 화합물, 퍼플루오로 테트라니트릴 화합물 및 이들의 조합으로 이루어진 군에서 선택되는 어느 하나인 것인 리튬 이차 전지용 전해질.The perfluoro nitrile compound is any one selected from the group consisting of perfluoro mononitrile compound, perfluoro dinitrile compound, perfluoro trinitrile compound, perfluoro tetranitrile compound and combinations thereof Electrolyte for secondary batteries.
  3. 제1항에 있어서, The method of claim 1,
    상기 퍼플루오로 니트릴 화합물은 하기 화학식 1 내지 4로 표시되는 것인 리튬 이차 전지용 전해질.The perfluoro nitrile compound is represented by the formula 1 to 4 electrolyte for a lithium secondary battery.
    [화학식 1][Formula 1]
    Figure PCTKR2016006587-appb-I000009
    Figure PCTKR2016006587-appb-I000009
    [화학식 2][Formula 2]
    Figure PCTKR2016006587-appb-I000010
    Figure PCTKR2016006587-appb-I000010
    [화학식 3][Formula 3]
    Figure PCTKR2016006587-appb-I000011
    Figure PCTKR2016006587-appb-I000011
    [화학식 4][Formula 4]
    Figure PCTKR2016006587-appb-I000012
    Figure PCTKR2016006587-appb-I000012
    상기 n은 1 내지 15이다.N is 1 to 15.
  4. 제1항에 있어서, The method of claim 1,
    상기 퍼플루오로 니트릴 화합물은 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile)인 것인 리튬 이차 전지용 전해질.The perfluoronitrile compound is a perfluorohexane-1,6-dinitrile (Perfluorohexane-1,6-dinitrile) electrolyte for a lithium secondary battery.
  5. 제4항에 있어서, The method of claim 4, wherein
    상기 리튬 이차 전지용 전해질은 헥산-1,6-디니트릴(hexane-1,6-dinitrile)을 더 포함하는 것인 리튬 이차 전지용 전해질.The lithium secondary battery electrolyte further comprises hexane-1,6-dinitrile (hexane-1,6-dinitrile) electrolyte for a lithium secondary battery.
  6. 제5항에 있어서, The method of claim 5,
    상기 헥산-1,6-디니트릴은 상기 퍼플루오로헥산-1,6-디니트릴 100 중량부에 대하여 1 내지 80 중량부로 포함되는 것인 리튬 이차 전지용 전해질.The hexane-1,6-dinitrile is an electrolyte for a lithium secondary battery that is contained in 1 to 80 parts by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile.
  7. 제1항에 있어서, The method of claim 1,
    상기 전해질은 유기 용매 및 리튬염을 더 포함하는 것인 리튬 이차 전지용 전해질.The electrolyte is a lithium secondary battery electrolyte further comprising an organic solvent and a lithium salt.
  8. 양극 활물질을 포함하는 양극, A positive electrode including a positive electrode active material,
    상기 양극과 대향 배치되며, 음극 활물질을 포함하는 음극, 그리고A negative electrode disposed to face the positive electrode and including a negative electrode active material; and
    상기 양극과 음극 사이에 개재되는 전해질을 포함하며,An electrolyte interposed between the positive electrode and the negative electrode,
    상기 전해질은 퍼플루오로 니트릴 화합물(perfluoro nitrile compounds)을 전해질 첨가제로 포함하는 리튬 이차 전지.The electrolyte is a lithium secondary battery comprising perfluoro nitrile compounds (perfluoro nitrile compounds) as an electrolyte additive.
  9. 제8항에 있어서, The method of claim 8,
    상기 퍼플루오로 니트릴 화합물은 퍼플루오로 모노니트릴 화합물, 퍼플루오로 디니트릴 화합물, 퍼플루오로 트리니트릴 화합물, 퍼플루오로 테트라니트릴 화합물 및 이들의 조합으로 이루어진 군에서 선택되는 어느 하나인 것인 리튬 이차 전지.The perfluoro nitrile compound is any one selected from the group consisting of perfluoro mononitrile compound, perfluoro dinitrile compound, perfluoro trinitrile compound, perfluoro tetranitrile compound and combinations thereof Secondary battery.
  10. 제8항에 있어서, The method of claim 8,
    상기 퍼플루오로 니트릴 화합물은 하기 화학식 1 내지 4로 표시되는 것인 리튬 이차 전지.The perfluoro nitrile compound is represented by the formula 1 to 4 lithium secondary battery.
    [화학식 1][Formula 1]
    Figure PCTKR2016006587-appb-I000013
    Figure PCTKR2016006587-appb-I000013
    [화학식 2][Formula 2]
    Figure PCTKR2016006587-appb-I000014
    Figure PCTKR2016006587-appb-I000014
    [화학식 3][Formula 3]
    Figure PCTKR2016006587-appb-I000015
    Figure PCTKR2016006587-appb-I000015
    [화학식 4][Formula 4]
    Figure PCTKR2016006587-appb-I000016
    Figure PCTKR2016006587-appb-I000016
    상기 n은 1 내지 15이다.N is 1 to 15.
  11. 제8항에 있어서,The method of claim 8,
    상기 전해질 첨가제는, 상기 전해질 총 중량에 대하여 0.1 내지 10 중량%로 포함되는 것인 리튬 이차 전지.The electrolyte additive, the lithium secondary battery will be included in 0.1 to 10% by weight based on the total weight of the electrolyte.
  12. 제8항에 있어서, The method of claim 8,
    상기 퍼플루오로 니트릴 화합물은 퍼플루오로헥산-1,6-디니트릴(Perfluorohexane-1,6-dinitrile)인 것인 리튬 이차 전지.The perfluoro nitrile compound is perfluorohexane-1,6-dinitrile (Perfluorohexane-1,6-dinitrile) is a lithium secondary battery.
  13. 제12항에 있어서, The method of claim 12,
    상기 리튬 이차 전지용 전해질은 헥산-1,6-디니트릴(hexane-1,6-dinitrile)을 더 포함하는 것인 리튬 이차 전지.The lithium secondary battery electrolyte further comprises a hexane-1,6-dinitrile (hexane-1,6-dinitrile) lithium secondary battery.
  14. 제13항에 있어서, The method of claim 13,
    상기 헥산-1,6-디니트릴은 상기 퍼플루오로헥산-1,6-디니트릴 100 중량부에 대하여 1 내지 80 중량부로 포함되는 것인 리튬 이차 전지.The hexane-1,6-dinitrile is a lithium secondary battery that is contained in 1 to 80 parts by weight based on 100 parts by weight of the perfluorohexane-1,6-dinitrile.
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