WO2018131953A1 - Composition for gel polymer electrolyte and lithium secondary battery comprising same - Google Patents

Composition for gel polymer electrolyte and lithium secondary battery comprising same Download PDF

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Publication number
WO2018131953A1
WO2018131953A1 PCT/KR2018/000647 KR2018000647W WO2018131953A1 WO 2018131953 A1 WO2018131953 A1 WO 2018131953A1 KR 2018000647 W KR2018000647 W KR 2018000647W WO 2018131953 A1 WO2018131953 A1 WO 2018131953A1
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group
polymer electrolyte
gel polymer
formula
carbon atoms
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PCT/KR2018/000647
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French (fr)
Korean (ko)
Inventor
이정훈
안경호
이철행
오정우
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주식회사 엘지화학
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Priority to US16/316,540 priority Critical patent/US10741874B2/en
Priority to JP2019516146A priority patent/JP6793998B2/en
Priority to EP18739273.3A priority patent/EP3467927B1/en
Priority to CN201880002751.3A priority patent/CN109451769B/en
Priority to PL18739273T priority patent/PL3467927T3/en
Priority claimed from KR1020180004665A external-priority patent/KR102109836B1/en
Publication of WO2018131953A1 publication Critical patent/WO2018131953A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/34—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from hydroxy compounds or their metallic derivatives
    • C08G65/48—Polymers modified by chemical after-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
    • C08J3/075—Macromolecular gels
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
    • 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
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • 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 a composition for a gel polymer electrolyte having improved high temperature safety and a lithium secondary battery including the same.
  • Electrochemical devices are the most attracting field of the energy storage technology field, and among them, interest in secondary batteries that can be charged and discharged is emerging.
  • lithium secondary batteries developed in the early 1990s have been in the spotlight for their high operating voltage and extremely high energy density.
  • an ion conductive nonaqueous electrolyte in which salts are dissolved in a non-aqueous organic solvent has been mainly used.
  • the nonaqueous electrolyte has a high possibility that the electrode material is degraded and the organic solvent is volatilized, and the safety of the nonaqueous electrolyte is low due to the combustion caused by the increase of the ambient temperature and the temperature of the battery itself.
  • gas is generated inside the battery due to decomposition of the carbonate organic solvent and / or side reaction between the organic solvent and the electrode, thereby expanding the battery thickness.
  • the gel polymer electrolyte proposed to improve the shortcomings of the non-aqueous electrolyte solution has excellent electrochemical stability, which not only maintains the thickness of the battery, but also has excellent contact between the electrode and the electrolyte due to the inherent adhesion of the gel. It is used for battery manufacturing.
  • a gel-forming composition is prepared by mixing a polymerizable monomer and a polymerization initiator in a non-aqueous organic solvent in which a salt is dissolved, and pouring the same into a battery containing an electrode assembly in which a cathode, an anode, and a separator are wound or stacked.
  • gelation crosslinking
  • a secondary battery containing a gel polymer electrolyte can be produced.
  • this method has the disadvantage of low safety in the heating process for wetting and gelation.
  • Another method is a method of coating a composition for a gel polymer electrolyte on the surface of a cathode and an anode separator, then gelating it using heat or UV, and then combining the same to prepare a battery, and additionally inject the existing electrolyte solution. Since the method further includes a non-aqueous organic solvent, it is not satisfied in terms of thermal stability and performance of a secondary battery.
  • the present invention has been made to solve such a problem.
  • the first technical problem of the present invention is to provide a composition for gel polymer electrolytes with improved wettability and high temperature safety.
  • a second technical problem of the present invention is to provide a gel polymer electrolyte formed by polymerizing the composition for gel polymer electrolyte.
  • the third technical problem of the present invention is to provide a lithium secondary battery having improved high temperature safety by including the gel polymer electrolyte.
  • composition for a gel polymer electrolyte comprising a polymerization initiator.
  • R 1 to R 3 are each independently an alkylene group having 1 to 4 carbon atoms unsubstituted or substituted with fluorine,
  • R 4 and R 5 are each independently an aliphatic hydrocarbon group or an aromatic hydrocarbon group
  • R 6 and R 7 are each independently an alkyl group having 1 to 10 carbon atoms or R 8 and R 9 are each independently an alkyl group having 1 to 10 carbon atoms or Is,
  • R 10 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group
  • R 11 is an alkylene group having 1 to 3 carbon atoms
  • R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms
  • n is an integer of any one of 1 to 70,
  • n is an integer of any one of 1-3.
  • the aliphatic hydrocarbon group may include an alicyclic hydrocarbon group or a linear hydrocarbon group.
  • the alicyclic hydrocarbon group may be a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms; Substituted or unsubstituted C4-C20 cycloalkylene group containing an isocyanate group (NCO); A substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms; And at least one selected from the group consisting of substituted or unsubstituted heterocycloalkylene groups having 2 to 20 carbon atoms.
  • the linear hydrocarbon group is substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; Substituted or unsubstituted C1-C20 alkylene group containing an isocyanate group (NCO); A substituted or unsubstituted alkoxylene group having 1 to 20 carbon atoms; A substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms; And at least one selected from the group consisting of a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms.
  • NCO isocyanate group
  • the aromatic hydrocarbon group is a substituted or unsubstituted arylene group having 6 to 20 carbon atoms; Or a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms.
  • the oligomer represented by Formula 1 may include an oligomer represented by Formula 1a.
  • R 4 and R 5 are each independently an aliphatic hydrocarbon group
  • R 8 and R 9 are each independently Is,
  • R 10 is an aliphatic hydrocarbon group
  • R 11 is an alkylene group having 1 to 3 carbon atoms
  • R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms
  • n is an integer of any one of 10 to 20,
  • n is an integer of any one of 1-2.
  • the oligomer represented by Formula 1a may include an oligomer represented by Formula 1a-1.
  • n is an integer of any one of 10-20.
  • the oligomer represented by Chemical Formula 1 may be included in an amount of 0.5 wt% to 20 wt%, specifically 0.5 wt% to 10 wt%, based on the total weight of the gel polymer electrolyte composition.
  • the weight average molecular weight (MW) of the oligomer represented by Formula 1 is 1,000 g / mol to 10,000 g / mol, specifically 3,000 g / mol to 8,000 g / mol, more specifically 3,000 g / mol to 5,000 g / may be mol.
  • an embodiment of the present invention provides a gel polymer electrolyte formed by polymerizing the gel polymer electrolyte composition in an inert atmosphere.
  • It provides a lithium secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and the gel polymer electrolyte of the present invention.
  • a composition for gel polymer electrolyte having improved wettability may be manufactured.
  • it can be used to provide a gel polymer electrolyte having a low surface tension with the surface of the electrode and forming a stable ion conductive film on the surface of the electrode during initial charging to prevent side reactions of the electrolyte.
  • the present invention can manufacture a lithium secondary battery having improved high temperature stability by providing such a gel polymer electrolyte.
  • composition for a gel polymer electrolyte comprising a polymerization initiator.
  • R 1 to R 3 are each independently an alkylene group having 1 to 4 carbon atoms unsubstituted or substituted with fluorine,
  • R 4 and R 5 are each independently an aliphatic hydrocarbon group or an aromatic hydrocarbon group
  • R 6 and R 7 are each independently an alkyl group having 1 to 10 carbon atoms or R 8 and R 9 are each independently an alkyl group having 1 to 10 carbon atoms or Is,
  • R 10 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group
  • R 11 is an alkylene group having 1 to 3 carbon atoms
  • R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms
  • n is an integer of any one of 1 to 70,
  • n is an integer of any one of 1-3.
  • the aliphatic hydrocarbon group may include an alicyclic hydrocarbon group or a linear hydrocarbon group.
  • the alicyclic hydrocarbon group may be a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms; Substituted or unsubstituted C4-C20 cycloalkylene group containing an isocyanate group (NCO); A substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms; And at least one selected from the group consisting of substituted or unsubstituted heterocycloalkylene groups having 2 to 20 carbon atoms.
  • the linear hydrocarbon group is substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; Substituted or unsubstituted C1-C20 alkylene group containing an isocyanate group (NCO); A substituted or unsubstituted alkoxylene group having 1 to 20 carbon atoms; A substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms; And at least one selected from the group consisting of a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms.
  • NCO isocyanate group
  • the aromatic hydrocarbon group is a substituted or unsubstituted arylene group having 6 to 20 carbon atoms; Or a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms.
  • the oligomer represented by Formula 1 may include an oligomer represented by Formula 1a.
  • R 4 and R 5 are each independently an aliphatic hydrocarbon group
  • R 8 and R 9 are each independently Is,
  • R 10 is an aliphatic hydrocarbon group
  • R 11 is an alkylene group having 1 to 3 carbon atoms
  • R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms
  • n is an integer of any one of 10 to 20,
  • n is an integer of any one of 1-2.
  • the oligomer represented by Formula 1a may include an oligomer represented by Formula 1a-1.
  • n is an integer of any one of 10-20.
  • the oligomer represented by the formula (1) contains an acrylate-based functional group which is a hydrophilic part capable of forming crosslinking at both ends, and a fluorine-substituted ethylene group which is a hydrophobic part.
  • the surface resistance with the electrode interface can be lowered by imparting a role of a surfactant in a battery. Therefore, the composition for the gel polymer electrolyte including the oligomer represented by Formula 1 may further improve the wettability effect.
  • the oligomer represented by Formula 1 includes an amide group and an electrochemically very stable fluorine-substituted ethylene group in the structure of the main chain, and thus, side reactions and lithium salts of lithium ions (Li + ).
  • the decomposition reaction and the like can be controlled, so that gas generation such as CO or CO 2 can be reduced during overcharging.
  • the gel polymer electrolyte composition it has excellent mechanical properties, thermal, chemical and oxidative stability, low surface tension with the electrode surface, and forms a stable ion conductive film on the electrode surface during initial charging to prevent side reactions of the electrolyte. It is possible to prepare a gel polymer electrolyte, and by including it can be produced a lithium secondary battery with improved high temperature safety.
  • the oligomer represented by Chemical Formula 1 may be included in an amount of 0.5 wt% to 20 wt%, specifically 0.5 wt% to 10 wt%, based on the total weight of the gel polymer electrolyte composition. If the content of the oligomer is less than 0.5% by weight, the effect of forming the gel reaction of the entire electrolyte is insufficient. If the content of the oligomer is more than 20% by weight, the oligomer is contained in an excessive amount to increase resistance and decrease the ion conductivity. May occur.
  • the weight average molecular weight (MW) of the oligomer represented by Formula 1 may be controlled by the number of repeating units, about 1,000 g / mol to 10,000 g / mol, specifically 3,000 g / mol to 8,000 g / mol, more specifically 3,000 g / mol to 5,000 g / mol.
  • the weight average molecular weight of the oligomer is in the above range, it is possible to effectively improve the mechanical strength of the battery comprising the same.
  • the weight average molecular weight of the oligomer is less than 1,000 g / mol, since the formation of the polymer matrix is difficult during the gel reaction, the effect of inhibiting the side reaction of the electrolyte may be reduced.
  • the weight average molecular weight of the oligomer exceeds 10,000 g / mol, the physical properties of the oligomer itself is rigid (rigid), and the affinity with the electrolyte solvent is low, so that it is difficult to dissolve, some of the dissolved electrolyte also has a high initial viscosity The electrolyte wettability in the battery may be significantly degraded, which may cause a decrease in the performance of the secondary battery.
  • the weight average molecular weight may mean a conversion value for standard polystyrene measured by gel permeation chromatography (GPC), and unless otherwise specified, molecular weight may mean weight average molecular weight.
  • GPC gel permeation chromatography
  • the GPC conditions are measured using Agilent's 1200 series, and the column used may be an Agilent PL mixed B column, and the solvent may be THF.
  • lithium salts included in the gel polymer electrolyte composition according to an embodiment of the present invention may be used without limitation, those conventionally used in electrolytes for lithium secondary batteries, for example, include Li + as the cation, and anion.
  • Li + as the cation, and anion. as F -, Cl -, Br - , I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, AlO 4 -, AlCl 4 -, PF 6 -, SbF 6 -, AsF 6 -, BF 2 C 2 O 4 -, BC 4 O 8 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF - , (CF 3) 6 P - , CF 3 SO 3 -, C 4 F 9 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -
  • the said lithium salt can also be used 1 type or in mixture of 2 or more types as needed.
  • the lithium salt may be appropriately changed within the range generally available, but in order to obtain an effect of forming an anti-corrosion coating on the surface of the electrode, a concentration of 0.8 M to 2 M, specifically 0.8 M to 1.5 M, in the composition for gel polymer electrolyte It can be included as.
  • the non-aqueous organic solvent included in the gel polymer electrolyte composition according to an embodiment of the present invention may minimize decomposition by an oxidation reaction or the like during charge and discharge of a secondary battery, and may exhibit desired properties with an additive. If there is, there is no limit.
  • an ether solvent, an ester solvent, an amide solvent, etc. can be used individually or in mixture of 2 or more types, respectively.
  • any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether and ethylpropyl ether, or a mixture of two or more thereof may be used. It is not limited to this.
  • the ester solvent may include at least one compound selected from the group consisting of a cyclic carbonate compound, a linear carbonate compound, a linear ester compound, and a cyclic ester compound.
  • cyclic carbonate compound examples include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, and 1,2-pentylene carbonate. , 2,3-pentylene carbonate, vinylene carbonate and fluoroethylene carbonate (FEC), or any one or a mixture of two or more thereof.
  • linear carbonate compound examples include dimethyl carbonate (dimethyl carbonate, DMC), diethyl carbonate (diethyl carbonate, DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate Any one selected from, or a mixture of two or more thereof may be representatively used, but is not limited thereto.
  • the linear ester compound is any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.
  • the above mixture and the like can be used representatively, but is not limited thereto.
  • the cyclic ester compound is any one selected from the group consisting of ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -caprolactone, ⁇ -valerolactone, ⁇ -caprolactone, or two or more thereof Mixtures may be used, but are not limited thereto.
  • the cyclic carbonate-based compound is a high viscosity organic solvent and has a high dielectric constant, and thus may be preferably used because it dissociates lithium salts in the electrolyte.
  • the cyclic carbonate-based compound has low viscosity and low viscosity such as dimethyl carbonate and diethyl carbonate.
  • the polymerization initiator may be used a conventional polymerization initiator known in the art.
  • a conventional polymerization initiator known in the art.
  • benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide are representative examples of the polymerization initiator.
  • organic peroxides such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide and hydrogen peroxide Hydroperoxides, 2,2'-azobis (2-cyanobutane), dimethyl 2,2'-azobis (2-methylpropionate), 2,2'-azobis (methylbutyronitrile) , 2,2'-azobis (isobutyronitrile) (AIBN; 2,2'-Azobis (iso-butyronitrile)) and 2,2'-azobisdimethyl-valeronitrile (AMVN; 2,2'- Azobisdimethyl-Valeronitrile), but there are one or more azo compounds selected from the group consisting of, but is not limited thereto.
  • organic peroxides such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide and hydrogen peroxide Hydroperoxides, 2,2'-azobis (2-cyanobutane), di
  • the polymerization initiator is decomposed by heat in the battery, non-limiting examples of 30 °C to 100 °C, specifically 60 °C to 80 °C heat or decomposition at room temperature (5 °C to 30 °C) to form a radical, free radical polymerization
  • the polymerizable oligomer can react to form a gel polymer electrolyte.
  • the polymerization initiator may be included in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the oligomer. When the polymerization initiator is more than 5 parts by weight, unreacted polymerization initiator may remain in the preparation of the gel polymer electrolyte, which may adversely affect battery performance. On the contrary, if the polymerization initiator is less than 0.1 part by weight, there is a problem that gelation does not occur well even under a certain temperature or more.
  • composition for a gel polymer electrolyte for lithium secondary battery may further include additional additives as necessary.
  • Additional additives usable in the present invention include vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone, alone or in combination of two or more thereof. Can be used.
  • the cyclic sulfites include ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5-dimethyl Propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite, 1,3-butylene glycol sulfite, and the like. Examples thereof include 1,3-propane sultone and 1,4-butane sultone.
  • unsaturated sultone examples include ethene sultone, 1,3-propene sultone, 1,4-butene sultone, 1-methyl-1,3 -Propene sulfone, and the like, and acyclic sulfones include divinyl sulfone, dimethyl sulfone, diethyl sulfone, methylethyl sulfone, and methyl vinyl sulfone.
  • the additional additives may be included in an amount of 0.01 to 5% by weight, specifically 0.01 to 3% by weight, based on the total amount of the composition for the gel polymer electrolyte by mixing two or more kinds thereof, and preferably 0.05 to 3% by weight.
  • amount of the additional additive is less than 0.01% by weight, the effect of improving the low temperature output, the high temperature storage characteristics and the high temperature life characteristics of the battery is insignificant, and when the content of the additional additive exceeds 5% by weight, the battery is charged and discharged. There is a possibility of excessive side reactions in the electrolyte.
  • the SEI film-forming additives may not be sufficiently decomposed at high temperatures when added in excess, and thus may remain unreacted or precipitated in the electrolyte at room temperature. Accordingly, a side reaction may occur in which the lifespan or resistance characteristics of the secondary battery are reduced.
  • an embodiment of the present invention provides a gel polymer electrolyte formed by polymerizing the gel polymer electrolyte composition in an inert atmosphere.
  • a cathode interposed between the cathode, the anode, the cathode and the anode, and
  • It provides a lithium secondary battery comprising the gel polymer electrolyte of the present invention.
  • the gel polymer electrolyte may be prepared by injecting the gel polymer electrolyte composition into a secondary battery and then curing the gel polymer electrolyte.
  • the gel polymer electrolyte may be formed by in-situ polymerization of the composition for gel polymer electrolyte in the secondary battery.
  • (a) inserting an electrode assembly consisting of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode in the battery case and (b) the gel polymer according to the present invention in the battery case may include the step of polymerizing after injecting the composition for the electrolyte to form a gel polymer electrolyte.
  • E-BEAM electron beam
  • gamma rays room temperature or high temperature aging process
  • thermal polymerization may be carried out through thermal polymerization.
  • the polymerization time takes about 2 minutes to 12 hours
  • the thermal polymerization temperature may be 60 °C to 100 °C, specifically 60 °C to 80 °C.
  • the in-situ polymerization reaction in a lithium secondary battery is added to a predetermined amount of the polymerization initiator and the oligomer in a gel polymer electrolyte composition containing a lithium salt and mixed and then injected into a battery cell.
  • the polymerization is carried out by heating at 60 ° C. to 80 ° C. for 1 to 20 hours, for example, to prepare a gel polymer electrolyte while gelling the composition for a lithium salt-containing gel polymer electrolyte.
  • the lithium secondary battery according to an embodiment of the present invention has a charge voltage of 3.0V to 5.0V, excellent capacity characteristics of the lithium secondary battery in both the normal voltage and the high voltage region.
  • the coating gel polymer electrolyte when implementing the coating gel polymer electrolyte using the gel polymer electrolyte of the present invention, it may further contain inorganic particles in the range of 10% to 25% by weight relative to the total weight of the gel polymer electrolyte.
  • the inorganic particles may be impregnated into the polymer network to allow the high viscosity solvent to penetrate well through the pores formed by the void space between the inorganic particles. That is, by including the inorganic particles, it is possible to obtain an effect of further improving the wettability to a high viscosity solvent by affinity between the polar substances and capillary phenomenon.
  • inorganic particles having a high dielectric constant and which do not generate an oxidation and / or reduction reaction in an operating voltage range of the lithium secondary battery (for example, 0 to 5V based on Li / Li + ) may be used.
  • the inorganic particles are BaTiO 3 , BaTiO 3 , Pb (Zr, Ti) O 3 (PZT), Pb 1 - a La a Zr 1 - b Ti b O 3 (PLZT) having a dielectric constant of 5 or more as a representative example thereof.
  • inorganic particles having lithium ion transfer ability that is, lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li c Ti d (PO 4 ) 3 , 0 ⁇ d ⁇ 2, 0 ⁇ d ⁇ 3 ), Lithium aluminum titanium phosphate (Li a1 Al b1 Ti c1 (PO 4 ) 3 , 0 ⁇ a1 ⁇ 2, 0 ⁇ b1 ⁇ 1, 0 ⁇ c1 ⁇ 3), 14Li 2 O-9Al 2 O 3 -38TiO 2- (LiAlTiP) a2 O b2 series glass such as 39P 2 O 5 (0 ⁇ a2 ⁇ 4, 0 ⁇ b2 ⁇ 13), lithium lanthanum titanate (Li a3 La b3 TiO 3 , 0 ⁇ a3 ⁇ 2, 0 ⁇ b3 ⁇ 3), Li 3 .
  • lithium phosphate Li 3 PO 4
  • lithium titanium phosphate Li c Ti d (PO
  • the average particle diameter of the inorganic particles is preferably in the range of about 0.001 to 10 ⁇ m in order to have a proper porosity in a uniform thickness in the gel polymer electrolyte. If the average particle size is less than 0.001 ⁇ m dispersibility may be lowered, if the average particle diameter is more than 10 ⁇ m not only can increase the thickness of the porous coating layer, but also agglomeration of inorganic particles occurs gel gel electrolyte Exposure to the outside can lower the mechanical strength.
  • the lithium secondary battery of the present invention can be prepared by injecting the gel polymer electrolyte composition of the present invention in an electrode structure consisting of a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, and then gelled.
  • the positive electrode, the negative electrode, and the separator constituting the electrode structure may be used all those conventionally used in the manufacture of a lithium secondary battery.
  • the positive electrode may be manufactured by forming a positive electrode mixture layer on a positive electrode current collector.
  • the cathode mixture layer may be formed by coating a cathode slurry including a cathode active material, a binder, a conductive material, a solvent, and the like on a cathode current collector, followed by drying and rolling.
  • the positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes in the battery.
  • the positive electrode current collector may be formed of stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. Surface treated with nickel, titanium, silver, or the like may be used.
  • the positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may specifically include a lithium composite metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. have. More specifically, the lithium composite metal oxide is a lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4, etc.), lithium-cobalt oxide (eg, LiCoO 2, etc.), lithium-nickel oxide (for example, LiNiO 2 and the like), lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O 2 (where, 0 ⁇ Y ⁇ 1), LiMn 2-z Ni z O 4 ( here, 0 ⁇ Z ⁇ 2) and the like), lithium-nickel-cobalt oxide (e.g., LiNi 1-Y1 Co Y1 O 2 (here, 0 ⁇ Y1 ⁇ 1) and the like), lithium-manganese-cobal
  • the lithium composite metal oxide may be LiCoO 2 , LiMnO 2 , LiNiO 2 , or lithium nickel manganese cobalt oxide (for example, Li (Ni 1/3 Mn 1/3 Co 1). / 3) O 2, Li ( Ni 0.6 Mn 0.2 Co 0.2) O 2, Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , Li (Ni 0.7 Mn 0.15 Co 0.15 ) O 2, and Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 , or the like, or lithium nickel cobalt aluminum oxide (eg, Li (Ni 0.8 Co 0.15 Al 0.05 ) O 2 , and the like.
  • Li ( Ni 0.6 Mn 0.2 Co 0.2) O 2 Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , Li (Ni 0.7 Mn 0.15 Co 0.15 ) O 2
  • the cathode active material may be included in an amount of 80 wt% to 99.5 wt%, specifically 85 wt% to 95 wt%, based on the total weight of solids in the cathode slurry.
  • the positive electrode active material content is 80% by weight or less, the energy density may be lowered and thus the capacity may be lowered.
  • the binder is a component that assists in bonding the active material and the conductive material to the current collector, and is generally added in an amount of 1 to 30 wt% based on the total weight of solids in the positive electrode slurry. 1 part by weight to 50 parts by weight, more specifically 3 parts by weight to 15 parts by weight, based on the total weight of solids in the positive electrode slurry.
  • the binder is less than 1 part by weight, the adhesive force between the electrode active material and the current collector may be insufficient.
  • the binder is more than 50 parts by weight, the adhesive force may be improved, but the content of the electrode active material may decrease, thereby lowering the battery capacity.
  • binders examples include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers, and the like.
  • CMC carboxymethyl cellulose
  • EPDM ethylene-propylene-diene terpolymer
  • EPDM ethylene-propylene-diene terpolymer
  • EPDM ethylene-propylene-diene terpolymer
  • sulfonated EPDM styrene-butadiene rubber
  • fluorine rubber various copolymers, and the like.
  • the conductive material is a material that imparts conductivity without causing chemical change to the battery, and may be added in an amount of 1 to 20 wt% based on the total weight of solids in the cathode slurry.
  • Such conductive materials include carbon powders such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; Graphite powders such as natural graphite, artificial graphite, or graphite with very advanced crystal structure; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials, such as polyphenylene derivatives, may be used.
  • carbon powders such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black
  • Graphite powders such as natural graphite, artificial graphite, or graphite with very advanced crystal structure
  • Conductive fibers such as carbon fibers and metal fibers
  • Metal powders such as carbon fluoride powder, aluminum powder and nickel powder
  • Conductive whiskeys such as zinc oxide and potassium titanate
  • Ketjenblack EC What is marketed by names, such as the series (made by Armak Company), Vulcan XC-72 (made by Cabot Company), and Super (P made by Timcal), can also be used.
  • the solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount that becomes a desirable viscosity when including the positive electrode active material and optionally a binder and a conductive material.
  • NMP N-methyl-2-pyrrolidone
  • the concentration of the solids in the slurry including the positive electrode active material and optionally the binder and the conductive material may be 10 wt% to 60 wt%, preferably 20 wt% to 50 wt%.
  • the negative electrode may be prepared by forming a negative electrode mixture layer on the negative electrode current collector.
  • the negative electrode mixture layer may be formed by coating a negative electrode slurry including a negative electrode active material, a binder, a conductive material, a solvent, and the like on a negative electrode current collector, followed by drying and rolling.
  • the negative electrode current collector generally has a thickness of 3 to 500 ⁇ m.
  • a negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery.
  • copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like on the surface, aluminum-cadmium alloy and the like can be used.
  • fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
  • the negative electrode active material may be lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal complex oxide, and may dope and undo lithium. At least one selected from the group consisting of materials, and transition metal oxide transition metal oxides.
  • any carbon-based negative electrode active material generally used in a lithium ion secondary battery may be used without particular limitation.
  • Examples thereof include crystalline carbon, Amorphous carbons or these may be used together.
  • Examples of the crystalline carbon include graphite such as amorphous, plate, flake, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (soft carbon) Or hard carbon, mesophase pitch carbide, calcined coke, or the like.
  • the metals or alloys of these metals with lithium include Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al And a metal selected from the group consisting of Sn or an alloy of these metals with lithium may be used.
  • the metal complex oxide may include PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 , Bi 2 O 5 , Li x Fe 2 O 3 (0 ⁇ x ⁇ 1), Li x WO 2 (0 ⁇ x ⁇ 1), and Sn x Me 1- x Me ' y O z (Me: Mn, Fe Me ': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 ⁇ x ⁇ 1;1 ⁇ y ⁇ 3; 1 ⁇ z ⁇ 8 Any one selected from the group can be used.
  • Examples of the material capable of doping and undoping lithium include Si, SiO x (0 ⁇ x ⁇ 2), Si-Y alloys (wherein Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, Is an element selected from the group consisting of rare earth elements and combinations thereof, not Si), Sn, SnO 2 , Sn-Y (Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth) An element selected from the group consisting of elements and combinations thereof, and not Sn; and at least one of these and SiO 2 may be mixed and used.
  • transition metal oxide examples include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, and the like.
  • the negative active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of solids in the negative electrode slurry.
  • the binder is a component that assists in the bonding between the conductive material, the active material and the current collector, and is typically added in an amount of 1 to 30 wt% based on the total weight of solids in the negative electrode slurry.
  • binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoro Low ethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, and the like.
  • PVDF polyvinylidene fluoride
  • CMC carboxymethyl cellulose
  • EPDM ethylene-propylene-diene polymer
  • sulfonated-EPDM styrene-butadiene rubber
  • the conductive material may be the same material as used in the production of the positive electrode, it may be added in 1 to 20% by weight based on the total weight of solids in the negative electrode slurry.
  • the solvent may include an organic solvent such as water or NMP (N-methyl-2-pyrrolidone), and may be used in an amount that becomes a desirable viscosity when including the negative electrode active material, and optionally a binder and a conductive material.
  • concentration of the negative electrode active material and, optionally, the solid content including the binder and the conductive material may be 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.
  • porous polymer films conventionally used as separators for example, polyolefins such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer, etc.
  • the porous polymer film made of the polymer may be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used. It is not.
  • the external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, square, pouch type, or coin type using a can.
  • a cathode active material LiNi 1/3 Co 1/ 3 Mn 1/3 O 2; NCM
  • a conductive material of carbon black (carbon black) 3% by weight of polyvinyl a binder fluoride (PVDF) 3 parts by weight % was added to the solvent N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode active material slurry (50% solids content).
  • NMP solvent N-methyl-2-pyrrolidone
  • the positive electrode active material slurry was applied to an aluminum (Al) thin film, which is a positive electrode current collector having a thickness of about 20 ⁇ m, dried to prepare a positive electrode, and then roll rolled to prepare a positive electrode.
  • Carbon powder as a negative electrode active material, PVDF as a binder and carbon black as a conductive material were added to NMP, which is 96% by weight, 3% by weight, and 1% by weight, respectively, to prepare a negative electrode active material slurry (solid content 80%).
  • NMP 96% by weight, 3% by weight, and 1% by weight, respectively.
  • the negative electrode active material slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 ⁇ m, and dried to prepare a negative electrode, followed by roll press, to prepare a negative electrode.
  • Cu copper
  • An electrode assembly was manufactured by sequentially stacking a separator consisting of the anode, the cathode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP).
  • An electrode assembly was prepared using a separator consisting of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and housed in a battery case, and injected the prepared gel polymer electrolyte composition. .
  • a lithium secondary battery comprising a gel polymer electrolyte thermally polymerized by heating at 65 ° C. for 5 hours was prepared.
  • the gel polymer electrolyte composition was prepared in the same manner as in Example 1, except that 10g of the compound of Formula 1a-1 and 0.2g of a polymerization initiator were added to 89.8g of the non-aqueous organic solvent. And a secondary battery comprising a gel polymer electrolyte using the same was prepared.
  • the gel polymer electrolyte composition was prepared in the same manner as in Example 1, except that 1 g of the compound of Formula 1a-1 and 0.02 g of a polymerization initiator were added to 98.98 g of the non-aqueous organic solvent. And a secondary battery comprising a gel polymer electrolyte using the same was prepared.
  • composition for a gel polymer electrolyte When preparing a composition for a gel polymer electrolyte, a composition for a gel polymer electrolyte and a composition thereof in the same manner as in Example 1 except that 20 g of the compound of Formula 1a-1 and 2 g of a polymerization initiator are added to 78 g of a non-aqueous organic solvent. A secondary battery including the used gel polymer electrolyte was prepared.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • a cathode active material LiNi 1/3 Co 1/ 3 Mn 1/3 O 2; NCM
  • a conductive material of carbon black (carbon black) 3% by weight of polyvinyl a binder fluoride (PVDF) 3 parts by weight % was added to the solvent N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode active material slurry (50% solids content).
  • NMP solvent N-methyl-2-pyrrolidone
  • the positive electrode active material slurry was applied to an aluminum (Al) thin film, which is a positive electrode current collector having a thickness of about 20 ⁇ m, dried to prepare a positive electrode, and then roll rolled to prepare a positive electrode.
  • Carbon powder as a negative electrode active material, PVDF as a binder and carbon black as a conductive material were added to NMP, which is 96% by weight, 3% by weight, and 1% by weight, respectively, to prepare a negative electrode active material slurry (solid content 80%).
  • NMP 96% by weight, 3% by weight, and 1% by weight, respectively.
  • the negative electrode active material slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 ⁇ m, and dried to prepare a negative electrode, followed by roll press, to prepare a negative electrode.
  • Cu copper
  • An electrode assembly was manufactured by sequentially stacking a separator consisting of the anode, the cathode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP).
  • An electrode assembly is manufactured by using a separator formed of three layers of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and stored in a battery case, followed by pouring the prepared nonaqueous electrolyte into a lithium secondary battery. (Full cell) was prepared.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • EDPTA ethoxylated tri-methylolpropane triacrylate
  • a polymerization initiator As a composition, 0.2 g of dimethyl 2,2'-azobis (2-methylpropionate) (CAS No. 2589-57-3) was added to prepare a gel polymer electrolyte composition.
  • a lithium secondary battery including a gel polymer electrolyte was manufactured in the same manner as in Example 1 except for using the prepared gel polymer electrolyte composition.
  • the secondary batteries including the gel polymer electrolytes of Examples 1 and 2, the secondary battery including the nonaqueous electrolyte of Comparative Example 1, and the secondary battery including the gel polymer electrolyte of Comparative Example 2 were stored at a high temperature of SOC at 100%, respectively. Thickness increase rate (%) was measured. The results are shown in FIG.
  • the thickness increase rate (%) of Figure 1 in the case of secondary batteries of Examples 1 and 2 using the composition for a gel polymer electrolyte containing an oligomer according to an embodiment of the present invention, the comparison using a non-aqueous electrolyte containing no oligomer Compared with the secondary battery of Comparative Example 2 using the composition for the secondary battery and the gel polymer electrolyte of Example 1, it can be seen that the thickness increase rate is significantly reduced after 4 weeks at 60 ° C.
  • the lithium secondary batteries prepared in Examples 3 to 10 were charged at 0.1C rate for 3 hours. Subsequently, degas / reseal and charge at a constant temperature / constant voltage condition up to 4.15V at 0.2C at room temperature, and discharge under constant current condition up to 3.0V at 0.2C were performed for initial charge and discharge. After initial charging and discharging, each was charged to 4.15V and stored at 60 ° C. for 6 weeks (state of charge (100%)), while maintaining capacity (%) and thickness change rate of the cell at week 6 to 0 parking. ) was measured.
  • the lithium secondary batteries prepared in Examples 3 to 6 have a capacity retention rate of about 94% or more after high temperature storage, and a thickness increase rate of about 7.5% or less after high temperature storage.
  • Example 7 having a composition for gel polymer electrolyte containing a small amount of oligomer was difficult to gel performance test was not possible.
  • the lithium secondary battery of Example 8 having an excess of oligomer-containing gel polymer electrolyte had a capacity retention of at least 90.1% after high temperature storage and a thickness increase rate of 15.9% after high temperature storage due to an increase in resistance in the electrolyte. It can be seen that the degradation compared to the lithium secondary battery manufactured in 6 to 6.
  • the capacity retention rate of the lithium secondary battery of Example 9 having a gel polymer electrolyte containing an oligomer having a low weight average molecular weight after the high temperature storage capacity is 91% or more
  • the thickness increase rate after high temperature storage is 10.8% gel polymer of the same conditions It can be seen that the reaction inferior in the reaction, deteriorated compared to the lithium secondary battery prepared in Examples 3 to 6.
  • the lithium secondary battery of Example 10 having a gel polymer electrolyte containing an oligomer having a high weight average molecular weight has a lowering of the wetting effect due to an increase in the viscosity of the gel polymer electrolyte composition. It can be seen that the secondary battery is degraded.

Abstract

The present invention relates to a composition for a gel polymer electrolyte, a gel polymer electrolyte prepared by polymerizing same, and a secondary battery comprising same, and more specifically, to a composition for a gel polymer electrolyte, the composition having enhanced high-temperature stability, a gel polymer electrolyte formed by polymerizing same under an inert atmosphere, and a lithium secondary battery comprising same.

Description

겔 폴리머 전해질용 조성물 및 이를 포함하는 리튬 이차전지Gel polymer electrolyte composition and lithium secondary battery comprising same
관련 출원(들)과의 상호 인용Cross Citation with Related Application (s)
본 출원은 2017년 1월 12일자 한국 특허 출원 제2017-0005599호 및 2018년 1월 12일자 한국 특허 출원 제2018-0004665호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된 모든 내용은 본 명세서의 일부로서 포함된다.This application claims the benefit of priority based on Korean Patent Application No. 2017-0005599 dated January 12, 2017 and Korean Patent Application No. 2018-0004665 dated January 12, 2018, and all disclosed in the literature of that Korean Patent Application. The contents are included as part of this specification.
기술분야Field of technology
본 발명은 고온 안전성이 개선된 겔 폴리머 전해질용 조성물 및 이를 포함하는 리튬 이차전지에 관한 것이다.The present invention relates to a composition for a gel polymer electrolyte having improved high temperature safety and a lithium secondary battery including the same.
최근 에너지 저장 기술에 대한 관심이 갈수록 높아지고 있다. 특히, 휴대폰, 캠코더 및 노트북 PC, 나아가서는 전기자동차에 까지 그 적용분야가 확대되면서, 에너지 저장 기술을 개발하기 위한 연구와 노력이 점점 구체화되고 있다.Recently, interest in energy storage technology is increasing. In particular, as the field of application extends to mobile phones, camcorders, notebook PCs, and even electric vehicles, research and efforts to develop energy storage technologies are increasingly materialized.
전기화학소자는 이러한 에너지 저장 기술 분야 중에서 가장 주목받고 있는 분야이며, 그 중에서도 충방전이 가능한 이차전지에 대한 관심이 대두되고 있다.Electrochemical devices are the most attracting field of the energy storage technology field, and among them, interest in secondary batteries that can be charged and discharged is emerging.
현재 적용되고 있는 이차전지 중에서 1990년대 초에 개발된 리튬 이차전지는 작동 전압이 높고 에너지 밀도가 월등히 크다는 점에서 각광을 받고 있다. Among the secondary batteries currently applied, lithium secondary batteries developed in the early 1990s have been in the spotlight for their high operating voltage and extremely high energy density.
종래 이차전지는 비수계 유기 용매에 염을 용해한 이온 전도성 비수전해액이 주로 사용되어 왔다.In the conventional secondary battery, an ion conductive nonaqueous electrolyte in which salts are dissolved in a non-aqueous organic solvent has been mainly used.
하지만, 상기 비수전해액은 전극 물질이 퇴화되고 유기 용매가 휘발될 가능성이 클 뿐만 아니라, 주변 온도 및 전지 자체의 온도 상승에 의한 연소에 의해 안전성이 낮다는 단점이 있다. 특히, 충방전 시 카보네이트 유기 용매의 분해 및/또는 유기 용매와 전극과의 부반응에 의해 전지 내부에 가스가 발생하여 전지 두께를 팽창시키는 문제점이 있다. However, the nonaqueous electrolyte has a high possibility that the electrode material is degraded and the organic solvent is volatilized, and the safety of the nonaqueous electrolyte is low due to the combustion caused by the increase of the ambient temperature and the temperature of the battery itself. In particular, when charging and discharging, gas is generated inside the battery due to decomposition of the carbonate organic solvent and / or side reaction between the organic solvent and the electrode, thereby expanding the battery thickness.
이러한 비수전해액의 단점을 개선하기 위하여 제안된 겔 폴리머 전해질은 전기화학적 안전성이 우수하여 전지의 두께를 일정하게 유지할 수 있을 뿐 아니라, 겔상 고유의 접착력으로 인해 전극과 전해질 사이의 접촉이 우수하기 때문에 박막형 전지 제조에 사용되고 있다.The gel polymer electrolyte proposed to improve the shortcomings of the non-aqueous electrolyte solution has excellent electrochemical stability, which not only maintains the thickness of the battery, but also has excellent contact between the electrode and the electrolyte due to the inherent adhesion of the gel. It is used for battery manufacturing.
상기 겔 폴리머 전해질을 적용한 이차전지의 제조 방법은 다음과 같이 2 가지 방법이 알려져 있다.As a method of manufacturing a secondary battery to which the gel polymer electrolyte is applied, two methods are known as follows.
우선, 염이 용해된 비수계 유기 용매에 중합 가능한 단량체 및 중합개시제를 혼합하여 겔 형성용 조성물을 제조하고, 이를 양극, 음극, 및 분리막이 권취 또는 적층된 전극조립체가 들어 있는 전지에 주액한 후, 적절한 온도와 시간 조건하에서 겔화(가교)시켜 겔형 폴리머 전해질을 함유한 이차전지를 제조할 수 있다. 하지만, 상기 방법은 젖음성(wetting) 및 겔화(gelation)를 위한 가열 공정 시에 안전성이 낮다는 단점이 있다.First, a gel-forming composition is prepared by mixing a polymerizable monomer and a polymerization initiator in a non-aqueous organic solvent in which a salt is dissolved, and pouring the same into a battery containing an electrode assembly in which a cathode, an anode, and a separator are wound or stacked. By gelation (crosslinking) under appropriate temperature and time conditions, a secondary battery containing a gel polymer electrolyte can be produced. However, this method has the disadvantage of low safety in the heating process for wetting and gelation.
또 다른 방법은, 양극, 음극 분리막 표면에 겔 폴리머 전해질용 조성물을 코팅한 다음, 열이나 UV를 이용하여 겔화시킨 다음, 이를 조합하여 전지를 제조하고, 기존 전해액을 추가 주액하는 방법이 있다. 상기 방법은 비수계 유기용매를 추가로 포함하기 때문에 열적 안정성뿐만 아니라 이차전지의 성능면에서 만족하지 못하고 있는 실정이다.Another method is a method of coating a composition for a gel polymer electrolyte on the surface of a cathode and an anode separator, then gelating it using heat or UV, and then combining the same to prepare a battery, and additionally inject the existing electrolyte solution. Since the method further includes a non-aqueous organic solvent, it is not satisfied in terms of thermal stability and performance of a secondary battery.
이에, 젖음성 및 고온 안정성 등의 성능이 개선된 겔 폴리머 전해질의 개발이 필요한 실정이다.Accordingly, there is a need for development of a gel polymer electrolyte having improved performance such as wettability and high temperature stability.
선행기술문헌Prior art literature
한국 공개특허공보 제2015-0125928호Korean Unexamined Patent Publication No. 2015-0125928
본 발명은 이와 같은 문제를 해결하기 위하여 안출된 것이다.The present invention has been made to solve such a problem.
본 발명의 제1 기술적 과제는 젖음성 및 고온 안전성이 향상된 겔 폴리머 전해질용 조성물을 제공하는 것이다.The first technical problem of the present invention is to provide a composition for gel polymer electrolytes with improved wettability and high temperature safety.
또한, 본 발명의 제2 기술적 과제는 상기 겔 폴리머 전해질용 조성물을 중합시켜 형성된 겔 폴리머 전해질을 제공하는 것이다.In addition, a second technical problem of the present invention is to provide a gel polymer electrolyte formed by polymerizing the composition for gel polymer electrolyte.
또한, 본 발명의 제3 기술적 과제는 상기 겔 폴리머 전해질을 포함함으로써, 고온 안전성이 향상된 리튬 이차전지를 제공하는 것이다. In addition, the third technical problem of the present invention is to provide a lithium secondary battery having improved high temperature safety by including the gel polymer electrolyte.
상기 과제를 해결하기 위하여, 본 발명의 일 실시예에서는In order to solve the above problems, in one embodiment of the present invention
리튬염; Lithium salts;
비수성 유기용매;Non-aqueous organic solvents;
하기 화학식 1로 표시되는 올리고머; 및An oligomer represented by Formula 1 below; And
중합개시제;를 포함하는 겔 폴리머 전해질용 조성물을 제공한다.It provides a composition for a gel polymer electrolyte comprising a polymerization initiator.
[화학식 1][Formula 1]
Figure PCTKR2018000647-appb-I000001
Figure PCTKR2018000647-appb-I000001
상기 화학식 1에서,In Chemical Formula 1,
R1 내지 R3는 각각 독립적으로 불소로 치환 또는 비치환된 탄소수 1 내지 4의 알킬렌기이고, R 1 to R 3 are each independently an alkylene group having 1 to 4 carbon atoms unsubstituted or substituted with fluorine,
R4 및 R5는 각각 독립적으로 지방족 탄화수소기 또는 방향족 탄화수소기이며,R 4 and R 5 are each independently an aliphatic hydrocarbon group or an aromatic hydrocarbon group,
R6 및 R7은 각각 독립적으로 탄소수 1 내지 10의 알킬기 또는
Figure PCTKR2018000647-appb-I000002
이고, 상기 R8 및 R9는 각각 독립적으로 탄소수 1 내지 10의 알킬기 또는
Figure PCTKR2018000647-appb-I000003
이며, R 6 and R 7 are each independently an alkyl group having 1 to 10 carbon atoms or
Figure PCTKR2018000647-appb-I000002
R 8 and R 9 are each independently an alkyl group having 1 to 10 carbon atoms or
Figure PCTKR2018000647-appb-I000003
Is,
R10은 지방족 탄화수소기 또는 방향족 탄화수소기이고,R 10 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group,
R11은 탄소수 1 내지 3의 알킬렌기이며, R 11 is an alkylene group having 1 to 3 carbon atoms,
R12는 수소 또는 탄소수 1 내지 2의 알킬기이고,R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms,
n은 1 내지 70 중 어느 하나의 정수이고,n is an integer of any one of 1 to 70,
m은 1 내지 3 중 어느 하나의 정수이다.m is an integer of any one of 1-3.
상기 화학식 1로 표시되는 올리고머에서, 상기 지방족 탄화수소기는 지환족 탄화수소기 또는 선형 탄화수소기를 포함할 수 있다.In the oligomer represented by Formula 1, the aliphatic hydrocarbon group may include an alicyclic hydrocarbon group or a linear hydrocarbon group.
상기 지환족 탄화소수기는 치환 또는 비치환된 탄소수 4 내지 20의 시클로알킬렌기; 이소시아네이트기(NCO)를 함유하는 치환 또는 비치환된 탄소수 4 내지 20의 시클로알킬렌기; 치환 또는 비치환된 탄소수 4 내지 20의 시클로알케닐렌기; 및 치환 또는 비치환된 탄소수 2 내지 20의 헤테로시클로알킬렌기로 이루어진 군으로부터 선택된 적어도 하나 이상을 들 수 있다.The alicyclic hydrocarbon group may be a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms; Substituted or unsubstituted C4-C20 cycloalkylene group containing an isocyanate group (NCO); A substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms; And at least one selected from the group consisting of substituted or unsubstituted heterocycloalkylene groups having 2 to 20 carbon atoms.
상기 선형 탄화수소기는 치환 또는 비치환된 탄소수 1 내지 20의 알킬렌기; 이소시아네이트기(NCO)를 함유하는 치환 또는 비치환된 탄소수 1 내지 20의 알킬렌기; 치환 또는 비치환된 탄소수 1 내지 20의 알콕실렌기; 치환 또는 비치환된 탄소수 2 내지 20의 알케닐렌기; 및 치환 또는 비치환된 탄소수 2 내지 20의 알키닐렌기로 이루어진 군으로부터 선택된 적어도 하나 이상을 들 수 있다.The linear hydrocarbon group is substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; Substituted or unsubstituted C1-C20 alkylene group containing an isocyanate group (NCO); A substituted or unsubstituted alkoxylene group having 1 to 20 carbon atoms; A substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms; And at least one selected from the group consisting of a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms.
또한, 상기 화학식 1로 표시되는 올리고머에서, 상기 방향족 탄화수소기는 치환 또는 비치환된 탄소수 6 내지 20의 아릴렌기; 또는 치환 또는 비치환된 탄소수 2 내지 20의 헤테로아릴렌기를 들 수 있다.In addition, in the oligomer represented by Formula 1, the aromatic hydrocarbon group is a substituted or unsubstituted arylene group having 6 to 20 carbon atoms; Or a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms.
구체적으로, 상기 화학식 1로 표시되는 올리고머는 하기 화학식 1a로 표시되는 올리고머를 들 수 있다.Specifically, the oligomer represented by Formula 1 may include an oligomer represented by Formula 1a.
[화학식 1a][Formula 1a]
Figure PCTKR2018000647-appb-I000004
Figure PCTKR2018000647-appb-I000004
상기 화학식 1a에서,In Chemical Formula 1a,
R4 및 R5는 각각 독립적으로 지방족 탄화수소기이며,R 4 and R 5 are each independently an aliphatic hydrocarbon group,
R8 및 R9는 각각 독립적으로
Figure PCTKR2018000647-appb-I000005
이며, R 8 and R 9 are each independently
Figure PCTKR2018000647-appb-I000005
Is,
R10은 지방족 탄화수소기이고, R11은 탄소수 1 내지 3의 알킬렌기이며, R 10 is an aliphatic hydrocarbon group, R 11 is an alkylene group having 1 to 3 carbon atoms,
R12는 수소 또는 탄소수 1 내지 2의 알킬기이고,R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms,
n은 10 내지 20 중 어느 하나의 정수이고,n is an integer of any one of 10 to 20,
m은 1 내지 2 중 어느 하나의 정수다.m is an integer of any one of 1-2.
보다 구체적으로, 상기 화학식 1a로 표시되는 올리고머는 하기 화학식 1a-1로 표시되는 올리고머를 들 수 있다.More specifically, the oligomer represented by Formula 1a may include an oligomer represented by Formula 1a-1.
[화학식 1a-1][Formula 1a-1]
Figure PCTKR2018000647-appb-I000006
Figure PCTKR2018000647-appb-I000006
상기 화학식 1a-1에서, In Chemical Formula 1a-1,
n은 10 내지 20 중 어느 하나의 정수다.n is an integer of any one of 10-20.
상기 화학식 1 표시되는 올리고머는 겔 폴리머 전해질용 조성물의 전체 중량을 기준으로 0.5 중량% 내지 20 중량%, 구체적으로 0.5 중량% 내지 10 중량%로 포함될 수 있다.The oligomer represented by Chemical Formula 1 may be included in an amount of 0.5 wt% to 20 wt%, specifically 0.5 wt% to 10 wt%, based on the total weight of the gel polymer electrolyte composition.
또한, 상기 화학식 1로 표시되는 올리고머의 중량평균분자량(MW)은 1,000 g/mol 내지 10,000 g/mol, 구체적으로 3,000 g/mol 내지 8,000 g/mol, 보다 구체적으로 3,000 g/mol 내지 5,000 g/mol 일 수 있다.In addition, the weight average molecular weight (MW) of the oligomer represented by Formula 1 is 1,000 g / mol to 10,000 g / mol, specifically 3,000 g / mol to 8,000 g / mol, more specifically 3,000 g / mol to 5,000 g / may be mol.
또한, 본 발명의 일 실시예에서는 상기 겔 폴리머 전해질용 조성물을 비활성 분위기하에서 중합시켜 형성된 겔 폴리머 전해질을 제공한다.In addition, an embodiment of the present invention provides a gel polymer electrolyte formed by polymerizing the gel polymer electrolyte composition in an inert atmosphere.
또한, 본 발명의 일 실시예에서는 In addition, in one embodiment of the present invention
음극, 양극, 상기 음극 및 양극 사이에 개재된 분리막, 및 본 발명의 겔 폴리머 전해질을 포함하는 리튬 이차전지를 제공한다.It provides a lithium secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and the gel polymer electrolyte of the present invention.
본 발명의 일 실시예에 따르면 친수성 및 소수성 관능기를 가지는 올리고머를 포함함으로써 젖음성이 향상된 겔 폴리머 전해질용 조성물을 제조할 수 있다. 또한, 이를 이용하여 전극 표면과의 표면장력이 낮고, 초기 충전시 전극 표면에 안정한 이온전도성 피막을 형성하여 전해질 부반응을 방지할 수 있는 겔 폴리머 전해질을 제공할 수 있다. 나아가, 본 발명은 이러한 겔 폴리머 전해질을 구비함으로써 고온 안정성이 향상된 리튬 이차전지를 제조할 수 있다.According to an embodiment of the present invention, by including an oligomer having hydrophilic and hydrophobic functional groups, a composition for gel polymer electrolyte having improved wettability may be manufactured. In addition, it can be used to provide a gel polymer electrolyte having a low surface tension with the surface of the electrode and forming a stable ion conductive film on the surface of the electrode during initial charging to prevent side reactions of the electrolyte. Furthermore, the present invention can manufacture a lithium secondary battery having improved high temperature stability by providing such a gel polymer electrolyte.
본 명세서에 첨부되는 다음의 도면들은 본 발명의 바람직한 실시예를 예시하는 것이며, 전술한 발명의 내용과 함께 본 발명의 기술 사상을 더욱 이해시키는 역할을 하는 것이므로, 본 발명은 그러한 도면에 기재된 사항에만 한정되어 해석되어서는 안 된다.The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the contents of the present invention, serve to further understand the technical idea of the present invention. It should not be construed as limited.
도 1은 본 발명의 실험예 1에 따른 이차전지의 고온 안전성 측정 결과를 나타낸 그래프이다.1 is a graph showing the high temperature safety measurement results of the secondary battery according to Experimental Example 1 of the present invention.
이하, 본 발명을 더욱 상세하게 설명한다. Hereinafter, the present invention will be described in more detail.
본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니 되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다.The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.
본 발명에서 특별한 언급이 없는 한 " * "는 동일하거나, 상이한 원자 또는 화학식의 말단부 간의 연결된 부분을 의미한다.Unless otherwise specified in the present invention, "*" means a moiety connected between the same or different atoms or terminal ends of the formula.
본 발명의 일 실시예에서는 In one embodiment of the present invention
비수성 유기용매;Non-aqueous organic solvents;
리튬염; Lithium salts;
하기 화학식 1로 표시되는 올리고머; 및An oligomer represented by Formula 1 below; And
중합개시제;를 포함하는 겔 폴리머 전해질용 조성물을 제공한다.It provides a composition for a gel polymer electrolyte comprising a polymerization initiator.
[화학식 1][Formula 1]
Figure PCTKR2018000647-appb-I000007
Figure PCTKR2018000647-appb-I000007
상기 화학식 1에서,In Chemical Formula 1,
R1 내지 R3는 각각 독립적으로 불소로 치환 또는 비치환된 탄소수 1 내지 4의 알킬렌기이고, R 1 to R 3 are each independently an alkylene group having 1 to 4 carbon atoms unsubstituted or substituted with fluorine,
R4 및 R5는 각각 독립적으로 지방족 탄화수소기 또는 방향족 탄화수소기이며,R 4 and R 5 are each independently an aliphatic hydrocarbon group or an aromatic hydrocarbon group,
R6 및 R7은 각각 독립적으로 탄소수 1 내지 10의 알킬기 또는
Figure PCTKR2018000647-appb-I000008
이고, 상기 R8 및 R9는 각각 독립적으로 탄소수 1 내지 10의 알킬기 또는
Figure PCTKR2018000647-appb-I000009
이며, R 6 and R 7 are each independently an alkyl group having 1 to 10 carbon atoms or
Figure PCTKR2018000647-appb-I000008
R 8 and R 9 are each independently an alkyl group having 1 to 10 carbon atoms or
Figure PCTKR2018000647-appb-I000009
Is,
이때 R10은 지방족 탄화수소기 또는 방향족 탄화수소기이고,Wherein R 10 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group,
R11은 탄소수 1 내지 3의 알킬렌기이며, R 11 is an alkylene group having 1 to 3 carbon atoms,
R12는 수소 또는 탄소수 1 내지 2의 알킬기이고,R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms,
n은 1 내지 70 중 어느 하나의 정수이고,n is an integer of any one of 1 to 70,
m은 1 내지 3 중 어느 하나의 정수이다.m is an integer of any one of 1-3.
이때, 상기 화학식 1로 표시되는 올리고머에서, 상기 지방족 탄화수소기는 지환족 탄화수소기 또는 선형 탄화수소기를 포함할 수 있다.In this case, in the oligomer represented by Formula 1, the aliphatic hydrocarbon group may include an alicyclic hydrocarbon group or a linear hydrocarbon group.
상기 지환족 탄화소수기는 치환 또는 비치환된 탄소수 4 내지 20의 시클로알킬렌기; 이소시아네이트기(NCO)를 함유하는 치환 또는 비치환된 탄소수 4 내지 20의 시클로알킬렌기; 치환 또는 비치환된 탄소수 4 내지 20의 시클로알케닐렌기; 및 치환 또는 비치환된 탄소수 2 내지 20의 헤테로시클로알킬렌기로 이루어진 군으로부터 선택된 적어도 하나 이상을 들 수 있다.The alicyclic hydrocarbon group may be a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms; Substituted or unsubstituted C4-C20 cycloalkylene group containing an isocyanate group (NCO); A substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms; And at least one selected from the group consisting of substituted or unsubstituted heterocycloalkylene groups having 2 to 20 carbon atoms.
상기 선형 탄화수소기는 치환 또는 비치환된 탄소수 1 내지 20의 알킬렌기; 이소시아네이트기(NCO)를 함유하는 치환 또는 비치환된 탄소수 1 내지 20의 알킬렌기; 치환 또는 비치환된 탄소수 1 내지 20의 알콕실렌기; 치환 또는 비치환된 탄소수 2 내지 20의 알케닐렌기; 및 치환 또는 비치환된 탄소수 2 내지 20의 알키닐렌기로 이루어진 군으로부터 선택된 적어도 하나 이상을 들 수 있다.The linear hydrocarbon group is substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; Substituted or unsubstituted C1-C20 alkylene group containing an isocyanate group (NCO); A substituted or unsubstituted alkoxylene group having 1 to 20 carbon atoms; A substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms; And at least one selected from the group consisting of a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms.
또한, 상기 화학식 1로 표시되는 올리고머에서, 상기 방향족 탄화수소기는 치환 또는 비치환된 탄소수 6 내지 20의 아릴렌기; 또는 치환 또는 비치환된 탄소수 2 내지 20의 헤테로아릴렌기를 들 수 있다.In addition, in the oligomer represented by Formula 1, the aromatic hydrocarbon group is a substituted or unsubstituted arylene group having 6 to 20 carbon atoms; Or a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms.
구체적으로, 상기 화학식 1로 표시되는 올리고머는 하기 화학식 1a로 표시되는 올리고머를 들 수 있다.Specifically, the oligomer represented by Formula 1 may include an oligomer represented by Formula 1a.
[화학식 1a][Formula 1a]
Figure PCTKR2018000647-appb-I000010
Figure PCTKR2018000647-appb-I000010
상기 화학식 1a에서,In Chemical Formula 1a,
R4 및 R5는 각각 독립적으로 지방족 탄화수소기이며,R 4 and R 5 are each independently an aliphatic hydrocarbon group,
R8 및 R9는 각각 독립적으로
Figure PCTKR2018000647-appb-I000011
이며, R 8 and R 9 are each independently
Figure PCTKR2018000647-appb-I000011
Is,
R10은 지방족 탄화수소기이고, R11은 탄소수 1 내지 3의 알킬렌기이며, R 10 is an aliphatic hydrocarbon group, R 11 is an alkylene group having 1 to 3 carbon atoms,
R12는 수소 또는 탄소수 1 내지 2의 알킬기이고,R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms,
n은 10 내지 20 중 어느 하나의 정수이고,n is an integer of any one of 10 to 20,
m은 1 내지 2 중 어느 하나의 정수다.m is an integer of any one of 1-2.
보다 구체적으로, 상기 화학식 1a로 표시되는 올리고머는 하기 화학식 1a-1로 표시되는 올리고머를 들 수 있다.More specifically, the oligomer represented by Formula 1a may include an oligomer represented by Formula 1a-1.
[화학식 1a-1][Formula 1a-1]
Figure PCTKR2018000647-appb-I000012
Figure PCTKR2018000647-appb-I000012
상기 화학식 1a-1에서, In Chemical Formula 1a-1,
n은 10 내지 20 중 어느 하나의 정수다.n is an integer of any one of 10-20.
본 발명의 겔 폴리머 전해질용 조성물에 있어서, 상기 화학식 1로 표시되는 올리고머는 양 말단에 자체적으로 가교 결합을 형성할 수 있는 친수성 부분인 아크릴레이트계 작용기를 함유하는 동시에, 소수성 부분인 불소 치환 에틸렌기를 포함하고 있기 때문에, 전지 내에서 계면활성제(surfactant) 역할을 부여하여 전극 계면과의 표면 저항을 낮출 수 있다. 따라서, 상기 화학식 1로 표시되는 올리고머를 포함하는 겔 폴리머 전해질용 조성물은 젖음성 효과가 보다 향상될 수 있다. 뿐만 아니라, 상기 화학식 1로 표시되는 올리고머는 주사슬 단위로 구조 중에 아미드기(amide group) 및 전기화학적으로 매우 안정한 불소 치환 에틸렌기를 포함함으로써, 리튬 이온 (Li+)의 부반응 및 리튬염(salt)의 분해 반응 등을 제어할 수 있으므로, 과충전 시에 CO 또는 CO2 등의 가스 발생을 저감할 수 있다. 이러한 겔 폴리머 전해질용 조성물을 이용하여 우수한 기계적 물성과 열적, 화학적 및 산화 안정성을 가지며, 전극 표면과의 표면장력이 낮고, 초기 충전시 전극 표면에 안정한 이온전도성 피막을 형성하여 전해질 부반응을 방지할 수 있는 겔 폴리머 전해질을 제조할 수 있으며, 이를 포함함으로써 고온 안전성이 향상된 리튬 이차전지를 제조할 수 있다. In the composition for a gel polymer electrolyte of the present invention, the oligomer represented by the formula (1) contains an acrylate-based functional group which is a hydrophilic part capable of forming crosslinking at both ends, and a fluorine-substituted ethylene group which is a hydrophobic part. As a result, the surface resistance with the electrode interface can be lowered by imparting a role of a surfactant in a battery. Therefore, the composition for the gel polymer electrolyte including the oligomer represented by Formula 1 may further improve the wettability effect. In addition, the oligomer represented by Formula 1 includes an amide group and an electrochemically very stable fluorine-substituted ethylene group in the structure of the main chain, and thus, side reactions and lithium salts of lithium ions (Li + ). The decomposition reaction and the like can be controlled, so that gas generation such as CO or CO 2 can be reduced during overcharging. By using the gel polymer electrolyte composition, it has excellent mechanical properties, thermal, chemical and oxidative stability, low surface tension with the electrode surface, and forms a stable ion conductive film on the electrode surface during initial charging to prevent side reactions of the electrolyte. It is possible to prepare a gel polymer electrolyte, and by including it can be produced a lithium secondary battery with improved high temperature safety.
본 발명의 일 실시예에 따르면, 상기 화학식 1로 표시되는 올리고머는 겔 폴리머 전해질용 조성물의 전체 중량을 기준으로 0.5 중량% 내지 20 중량%, 구체적으로 0.5 중량% 내지 10 중량%로 포함될 수 있다. 만약, 상기 올리고머의 함량이 0.5 중량% 미만이면 전해질 전체의 겔 반응 형성 효과가 불충분하고, 올리고머의 함량이 20 중량%를 초과하면 올리고머가 과량 함유되어 저항이 증가하고, 이온전도도가 감소하는 단점이 발생할 수 있다. According to one embodiment of the present invention, the oligomer represented by Chemical Formula 1 may be included in an amount of 0.5 wt% to 20 wt%, specifically 0.5 wt% to 10 wt%, based on the total weight of the gel polymer electrolyte composition. If the content of the oligomer is less than 0.5% by weight, the effect of forming the gel reaction of the entire electrolyte is insufficient. If the content of the oligomer is more than 20% by weight, the oligomer is contained in an excessive amount to increase resistance and decrease the ion conductivity. May occur.
또한, 본 발명의 일 실시예에 따르면, 상기 화학식 1로 표시되는 올리고머의 중량평균 분자량(MW)은 반복 단위의 개수에 의해 조절될 수 있으며, 약 1,000 g/mol 내지 10,000 g/mol, 구체적으로 3,000 g/mol 내지 8,000 g/mol, 보다 구체적으로 3,000 g/mol 내지 5,000 g/mol일 수 있다. In addition, according to an embodiment of the present invention, the weight average molecular weight (MW) of the oligomer represented by Formula 1 may be controlled by the number of repeating units, about 1,000 g / mol to 10,000 g / mol, specifically 3,000 g / mol to 8,000 g / mol, more specifically 3,000 g / mol to 5,000 g / mol.
상기 올리고머의 중량평균분자량이 상기 범위 내인 경우, 이를 포함하는 전지의 기계적 강도를 효과적으로 개선할 수 있다. When the weight average molecular weight of the oligomer is in the above range, it is possible to effectively improve the mechanical strength of the battery comprising the same.
만약, 상기 올리고머의 중량평균분자량이 1,000 g/mol 미만이면, 겔 반응 진행 시 고분자 매트릭스 형성이 어렵기 때문에, 전해질 부반응 억제 효과가 감소될 수 있다. 상기 올리고머의 중량평균분자량이 10,000 g/mol을 초과하면, 올리고머의 물성 자체가 경직(rigid)되고, 전해질 용매와 친화성이 낮아져 용해가 어려워질 뿐만 아니라, 일부 용해된 전해질도 그 점도가 높아 초기 전지 내 전해질 젖음성을 현저히 떨어뜨려, 이차전지의 성능 저하를 야기할 수 있다.If the weight average molecular weight of the oligomer is less than 1,000 g / mol, since the formation of the polymer matrix is difficult during the gel reaction, the effect of inhibiting the side reaction of the electrolyte may be reduced. When the weight average molecular weight of the oligomer exceeds 10,000 g / mol, the physical properties of the oligomer itself is rigid (rigid), and the affinity with the electrolyte solvent is low, so that it is difficult to dissolve, some of the dissolved electrolyte also has a high initial viscosity The electrolyte wettability in the battery may be significantly degraded, which may cause a decrease in the performance of the secondary battery.
상기 중량평균분자량은 GPC(Gel Permeation Chromatograph)로 측정한 표준 폴리스티렌에 대한 환산 수치를 의미할 수 있고, 특별하게 달리 규정하지 않는 한, 분자량은 중량평균분자량을 의미할 수 있다. 예컨대, 본 발명에서는 GPC 조건으로 Agilent社 1200시리즈를 이용하여 측정하며, 이때 사용된 컬럼은 Agilent社 PL mixed B 컬럼을 이용할 수 있고, 용매는 THF를 사용할 수 있다.The weight average molecular weight may mean a conversion value for standard polystyrene measured by gel permeation chromatography (GPC), and unless otherwise specified, molecular weight may mean weight average molecular weight. For example, in the present invention, the GPC conditions are measured using Agilent's 1200 series, and the column used may be an Agilent PL mixed B column, and the solvent may be THF.
한편, 본 발명의 일 실시예에 따른 겔 폴리머 전해질용 조성물에 포함되는 리튬염은 리튬 이차전지용 전해질에 통상적으로 사용되는 것들이 제한 없이 사용될 수 있으며, 예를 들어 상기 양이온으로 Li+를 포함하고, 음이온으로 F-, Cl-, Br-, I-, NO3 -, N(CN)2 -, BF4 -, ClO4 -, AlO4 -, AlCl4 -, PF6 -, SbF6 -, AsF6 -, BF2C2O4 -, BC4O8 -, (CF3)2PF4 -, (CF3)3PF3 -, (CF3)4PF2 -, (CF3)5PF-, (CF3)6P-, CF3SO3 -, C4F9SO3 -, CF3CF2SO3 -, (CF3SO2)2N-, (F2SO2)2N-, CF3CF2(CF3)2CO-, (CF3SO2)2CH-, CF3(CF2)7SO3 -, CF3CO2 -, CH3CO2 -, SCN- 및 (CF3CF2SO2)2N-로 이루어진 군으로부터 선택된 적어도 어느 하나를 포함할 수 있다. 상기 리튬염은 1종 또는 필요에 따라서 2종 이상을 혼합하여 사용할 수도 있다. 상기 리튬염은 통상적으로 사용 가능한 범위 내에서 적절히 변경할 수 있으나, 최적의 전극 표면의 부식 방지용 피막 형성 효과를 얻기 위하여, 겔 폴리머 전해질용 조성물 내에 0.8 M 내지 2M, 구체적으로 0.8M 내지 1.5M의 농도로 포함할 수 있다. Meanwhile, lithium salts included in the gel polymer electrolyte composition according to an embodiment of the present invention may be used without limitation, those conventionally used in electrolytes for lithium secondary batteries, for example, include Li + as the cation, and anion. as F -, Cl -, Br - , I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, AlO 4 -, AlCl 4 -, PF 6 -, SbF 6 -, AsF 6 -, BF 2 C 2 O 4 -, BC 4 O 8 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF - , (CF 3) 6 P - , CF 3 SO 3 -, C 4 F 9 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (F 2 SO 2) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO -, (CF 3 SO 2) 2 CH -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN - and ( CF 3 CF 2 SO 2 ) 2 N - It may include at least one selected from the group consisting of. The said lithium salt can also be used 1 type or in mixture of 2 or more types as needed. The lithium salt may be appropriately changed within the range generally available, but in order to obtain an effect of forming an anti-corrosion coating on the surface of the electrode, a concentration of 0.8 M to 2 M, specifically 0.8 M to 1.5 M, in the composition for gel polymer electrolyte It can be included as.
또한, 본 발명의 일 실시예에 따른 겔 폴리머 전해질용 조성물에 포함되는 비수성 유기 용매는 이차전지의 충방전 과정에서 산화 반응 등에 의한 분해가 최소화될 수 있고, 첨가제와 함께 목적하는 특성을 발휘할 수 있는 것이라면 제한이 없다. 예를 들면 에테르계 용매, 에스테르계 용매, 또는 아미드계 용매 등을 각각 단독으로 또는 2종 이상 혼합하여 사용할 수 있다. In addition, the non-aqueous organic solvent included in the gel polymer electrolyte composition according to an embodiment of the present invention may minimize decomposition by an oxidation reaction or the like during charge and discharge of a secondary battery, and may exhibit desired properties with an additive. If there is, there is no limit. For example, an ether solvent, an ester solvent, an amide solvent, etc. can be used individually or in mixture of 2 or more types, respectively.
상기 유기용매 중 에테르계 용매로는 디메틸에테르, 디에틸에테르, 디프로필 에테르, 메틸에틸에테르, 메틸프로필 에테르 및 에틸프로필 에테르로 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 사용할 수 있으나, 이에 한정되는 것은 아니다.As the ether solvent in the organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether and ethylpropyl ether, or a mixture of two or more thereof may be used. It is not limited to this.
또한, 상기 에스테르계 용매는 환형 카보네이트 화합물, 선형 카보네이트 화합물, 선형 에스테르 화합물, 및 환형 에스테르 화합물로 이루어진 군으로부터 선택된 적어도 하나 이상의 화합물을 포함할 수 있다. In addition, the ester solvent may include at least one compound selected from the group consisting of a cyclic carbonate compound, a linear carbonate compound, a linear ester compound, and a cyclic ester compound.
이중 상기 환형 카보네이트 화합물의 구체적인 예로는 에틸렌 카보네이트(ethylene carbonate, EC), 프로필렌 카보네이트(propylene carbonate, PC), 1,2-부틸렌 카보네이트, 2,3-부틸렌 카보네이트, 1,2-펜틸렌카보네이트, 2,3-펜틸렌 카보네이트, 비닐렌 카보네이트 및 플루오로에틸렌 카보네이트 (FEC)으로 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물이 있다.Specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, and 1,2-pentylene carbonate. , 2,3-pentylene carbonate, vinylene carbonate and fluoroethylene carbonate (FEC), or any one or a mixture of two or more thereof.
또한, 상기 선형 카보네이트 화합물의 구체적인 예로는 디메틸 카보네이트(dimethyl carbonate, DMC), 디에틸 카보네이트(diethyl carbonate, DEC), 디프로필 카보네이트, 에틸메틸 카보네이트(EMC), 메틸프로필 카보네이트 및 에틸프로필 카보네이트로 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물 등이 대표적으로 사용될 수 있으나, 이에 한정되는 것은 아니다.In addition, specific examples of the linear carbonate compound include dimethyl carbonate (dimethyl carbonate, DMC), diethyl carbonate (diethyl carbonate, DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate Any one selected from, or a mixture of two or more thereof may be representatively used, but is not limited thereto.
상기 선형 에스테르 화합물은 그 구체적인 예로 메틸 아세테이트, 에틸 아세테이트, 프로필 아세테이트, 메틸 프로피오네이트, 에틸 프로피오네이트, 프로필 프로피오네이트, 및 부틸 프로피오네이트로 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물 등이 대표적으로 사용될 수 있으나, 이에 한정되는 것은 아니다.The linear ester compound is any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. The above mixture and the like can be used representatively, but is not limited thereto.
상기 환형 에스테르 화합물은 그 구체적인 예로 γ-부티로락톤, γ-발레로락톤, γ-카프로락톤, σ-발레로락톤, ε-카프로락톤과 같은 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 사용할 수 있으나, 이에 한정되는 것은 아니다.The cyclic ester compound is any one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, ε-caprolactone, or two or more thereof Mixtures may be used, but are not limited thereto.
상기 에스테르계 용매 중에서 환형 카보네이트계 화합물은 고점도의 유기용매로서 유전율이 높아 전해질 내의 리튬염을 잘 해리시키므로 바람직하게 사용될 수 있으며, 이러한 환형 카보네이트계 화합물에 디메틸 카보네이트 및 디에틸 카보네이트와 같은 저점도, 저유전율 선형 카보네이트계 화합물 및 선형 에스테르계 화합물을 적당한 비율로 혼합하여 사용하면 높은 전기 전도율을 갖는 겔 폴리머 전해질을 만들 수 있어 더욱 바람직하게 사용될 수 있다.In the ester solvent, the cyclic carbonate-based compound is a high viscosity organic solvent and has a high dielectric constant, and thus may be preferably used because it dissociates lithium salts in the electrolyte. The cyclic carbonate-based compound has low viscosity and low viscosity such as dimethyl carbonate and diethyl carbonate. When the dielectric constant linear carbonate compound and the linear ester compound are mixed and used in an appropriate ratio, a gel polymer electrolyte having high electrical conductivity can be made, and thus it can be more preferably used.
또한, 본 발명의 일 실시예에 따른 겔 폴리머 전해질용 조성물에 있어서, 상기 중합개시제는 당 업계에 알려진 통상적인 중합개시제가 사용될 수 있다. 예를 들면, 상기 중합개시제의 그 대표적인 예로 벤조일 퍼옥사이드(benzoyl peroxide), 아세틸 퍼옥사이드(acetyl peroxide), 디라우릴 퍼옥사이드(dilauryl peroxide), 디-tert-부틸 퍼옥사이드(di-tert-butyl peroxide), t-부틸 퍼옥시-2-에틸-헥사노에이트(t-butyl peroxy-2-ethyl-hexanoate), 큐밀 하이드로퍼옥사이드(cumyl hydroperoxide) 및 하이드로겐 퍼옥사이드(hydrogen peroxide) 등의 유기과산화물류나 히드로과산화물류와 2,2'-아조비스(2-시아노부탄), 디메틸 2,2'-아조비스(2-메틸프로피오네이트), 2,2'-아조비스(메틸부티로니트릴), 2,2'-아조비스(이소부티로니트릴)(AIBN; 2,2'-Azobis(iso-butyronitrile)) 및 2,2'-아조비스디메틸-발레로니트릴(AMVN; 2,2'-Azobisdimethyl-Valeronitrile)로 이루어진 군에서 선택된 1종 이상 아조 화합물류 등이 있으나, 이에 한정하지 않는다.In addition, in the gel polymer electrolyte composition according to an embodiment of the present invention, the polymerization initiator may be used a conventional polymerization initiator known in the art. For example, benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide are representative examples of the polymerization initiator. ), organic peroxides such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide and hydrogen peroxide Hydroperoxides, 2,2'-azobis (2-cyanobutane), dimethyl 2,2'-azobis (2-methylpropionate), 2,2'-azobis (methylbutyronitrile) , 2,2'-azobis (isobutyronitrile) (AIBN; 2,2'-Azobis (iso-butyronitrile)) and 2,2'-azobisdimethyl-valeronitrile (AMVN; 2,2'- Azobisdimethyl-Valeronitrile), but there are one or more azo compounds selected from the group consisting of, but is not limited thereto.
상기 중합개시제는 전지 내에서 열, 비제한적인 예로 30℃ 내지 100℃, 구체적으로 60℃ 내지 80℃의 열에 의해 분해되거나 상온(5℃ 내지 30℃)에서 분해되어 라디칼을 형성하고, 자유라디칼 중합에 의해 중합성 올리고머가 반응하여 겔 폴리머 전해질을 형성할 수 있다.The polymerization initiator is decomposed by heat in the battery, non-limiting examples of 30 ℃ to 100 ℃, specifically 60 ℃ to 80 ℃ heat or decomposition at room temperature (5 ℃ to 30 ℃) to form a radical, free radical polymerization The polymerizable oligomer can react to form a gel polymer electrolyte.
상기 중합개시제는 상기 올리고머 100 중량부에 대하여 0.1 중량부 내지 5 중량부로 포함될 수 있다. 상기 중합개시제가 5 중량부를 초과하는 경우, 겔 폴리머 전해질 제조 시에 미반응 중합개시제가 잔류하여 전지 성능에 악영향을 미질 수 있다. 반대로 상기 중합개시제가 0.1 중량부 미만이면 일정 온도 이상의 조건에서도 겔화가 잘 이루어지지 않는 문제가 있다.The polymerization initiator may be included in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the oligomer. When the polymerization initiator is more than 5 parts by weight, unreacted polymerization initiator may remain in the preparation of the gel polymer electrolyte, which may adversely affect battery performance. On the contrary, if the polymerization initiator is less than 0.1 part by weight, there is a problem that gelation does not occur well even under a certain temperature or more.
한편, 본 발명의 일 실시예에 따른 리튬 이차전지용 겔 폴리머 전해질용 조성물은 필요에 따라서 부가적 첨가제를 더 포함할 수도 있다. 본 발명에서 사용 가능한 부가적 첨가제로는 비닐렌 카보네이트, 비닐에틸렌카보네이트, 플루오로에틸렌 카보네이트, 비닐에틸렌 카보네이트, 환형 설파이트, 포화 설톤, 불포화 설톤, 비환형 설폰 등을 각각 단독으로 또는 2종 이상 혼합하여 사용할 수 있다.Meanwhile, the composition for a gel polymer electrolyte for lithium secondary battery according to an embodiment of the present invention may further include additional additives as necessary. Additional additives usable in the present invention include vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone, alone or in combination of two or more thereof. Can be used.
이때, 상기 환형 설파이트로는 에틸렌 설파이트, 메틸 에틸렌 설파이트, 에틸 에틸렌 설파이트, 4,5-디메틸 에틸렌 설파이트, 4,5-디에틸 에틸렌 설파이트, 프로필렌 설파이트, 4,5-디메틸 프로필렌 설파이트, 4,5-디에틸 프로필렌설파이트, 4,6-디메틸 프로필렌 설파이트, 4,6-디에틸 프로필렌 설파이트, 1,3-부틸렌 글리콜 설파이트 등을 들 수 있으며, 포화 설톤으로는 1,3-프로판 설톤, 1,4-부탄 설톤 등을 들 수 있으며, 불포화 설톤으로는 에텐설톤, 1,3-프로펜 설톤, 1,4-부텐 설톤, 1-메틸-1,3-프로펜 설톤 등을 들 수 있으며, 비환형 설폰으로는 디비닐설폰, 디메틸 설폰, 디에틸 설폰, 메틸에틸 설폰, 메틸비닐 설폰 등을 들 수 있다.At this time, the cyclic sulfites include ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5-dimethyl Propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite, 1,3-butylene glycol sulfite, and the like. Examples thereof include 1,3-propane sultone and 1,4-butane sultone. Examples of unsaturated sultone include ethene sultone, 1,3-propene sultone, 1,4-butene sultone, 1-methyl-1,3 -Propene sulfone, and the like, and acyclic sulfones include divinyl sulfone, dimethyl sulfone, diethyl sulfone, methylethyl sulfone, and methyl vinyl sulfone.
상기 부가적 첨가제들은 2 종 이상이 혼합되어 겔 폴리머 전해질용 조성물 총량을 기준으로 0.01 내지 5 중량%, 구체적으로 0.01 내지 3 중량%로 포함될 수 있으며, 바람직하게는 0.05 내지 3 중량% 일 수 있다. 상기 부가적 첨가제의 함량이 0.01 중량% 보다 적으면 전지의 저온 출력 개선 및 고온 저장 특성 및 고온 수명 특성 개선의 효과가 미미하고, 상기 부가적 첨가제의 함량이 5 중량%를 초과하면 전지의 충방전시 전해질 내의 부반응이 과도하게 발생할 가능성이 있다. 특히, 상기 SEI 막 형성용 첨가제들이 과량으로 첨가될 시에 고온에서 충분히 분해되지 못하여, 상온에서 전해질 내에서 미반응물 또는 석출된 채로 존재하고 있을 수 있다. 이에 따라 이차전지의 수명 또는 저항특성이 저하되는 부반응이 발생할 수 있다.The additional additives may be included in an amount of 0.01 to 5% by weight, specifically 0.01 to 3% by weight, based on the total amount of the composition for the gel polymer electrolyte by mixing two or more kinds thereof, and preferably 0.05 to 3% by weight. When the amount of the additional additive is less than 0.01% by weight, the effect of improving the low temperature output, the high temperature storage characteristics and the high temperature life characteristics of the battery is insignificant, and when the content of the additional additive exceeds 5% by weight, the battery is charged and discharged. There is a possibility of excessive side reactions in the electrolyte. In particular, the SEI film-forming additives may not be sufficiently decomposed at high temperatures when added in excess, and thus may remain unreacted or precipitated in the electrolyte at room temperature. Accordingly, a side reaction may occur in which the lifespan or resistance characteristics of the secondary battery are reduced.
또한, 본 발명의 일 실시예에서는 상기 겔 폴리머 전해질용 조성물을 비활성 분위기하에서 중합시켜 형성된 겔 폴리머 전해질을 제공한다.In addition, an embodiment of the present invention provides a gel polymer electrolyte formed by polymerizing the gel polymer electrolyte composition in an inert atmosphere.
또한, 본 발명의 일 실시예에서는 In addition, in one embodiment of the present invention
음극, 양극, 상기 음극 및 양극 사이에 개재된 분리막, 및 A cathode interposed between the cathode, the anode, the cathode and the anode, and
본 발명의 겔 폴리머 전해질을 포함하는 리튬 이차전지를 제공한다.It provides a lithium secondary battery comprising the gel polymer electrolyte of the present invention.
구체적으로, 상기 겔 폴리머 전해질은 이차전지 내에 상기 겔 폴리머 전해질용 조성물을 주액한 후 경화반응시켜 제조될 수 있다.Specifically, the gel polymer electrolyte may be prepared by injecting the gel polymer electrolyte composition into a secondary battery and then curing the gel polymer electrolyte.
예를 들면, 겔 폴리머 전해질은 이차전지의 내부에서 상기 겔 폴리머 전해질용 조성물을 in-situ 중합하여 형성될 수 있다.For example, the gel polymer electrolyte may be formed by in-situ polymerization of the composition for gel polymer electrolyte in the secondary battery.
더욱 구체적인 일 실시 형태를 들면, (a) 양극, 음극, 및 상기 양극과 음극 사이에 개재된 분리막으로 이루어진 전극 조립체를 전지 케이스에 삽입하는 단계 및 (b) 상기 전지 케이스에 본 발명에 따른 겔 폴리머 전해질용 조성물을 주입한 후 중합시켜 겔 폴리머 전해질을 형성하는 단계를 포함할 수 있다.For a more specific embodiment, (a) inserting an electrode assembly consisting of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode in the battery case and (b) the gel polymer according to the present invention in the battery case It may include the step of polymerizing after injecting the composition for the electrolyte to form a gel polymer electrolyte.
리튬 이차전지 내 in-situ 중합 반응은 전자빔(E-BEAM), 감마선, 상온 또는 고온 에이징 공정을 통하여 가능하며, 본 발명의 일 실시예에 따르면 열 중합을 통해 진행될 수 있다. 이때, 중합 시간은 대략 2분 내지 12시간 정도 소요되며, 열 중합 온도는 60℃ 내지 100℃, 구체적으로 60℃ 내지 80℃ 가 될 수 있다.In -situ polymerization reaction in the lithium secondary battery is possible through an electron beam (E-BEAM), gamma rays, room temperature or high temperature aging process, according to an embodiment of the present invention may be carried out through thermal polymerization. At this time, the polymerization time takes about 2 minutes to 12 hours, the thermal polymerization temperature may be 60 ℃ to 100 ℃, specifically 60 ℃ to 80 ℃.
보다 구체적으로 리튬 이차전지 내 in-situ 중합 반응은 리튬염이 포함되어 있는 겔 폴리머 전해질용 조성물에 중합개시제와 상기 올리고머를 소정량 첨가하여 혼합한 후 전지셀에 주액한다. 그러한 전지셀의 주액구를 밀봉한 후, 예를 들면 60℃ 내지 80℃로 1 내지 20 시간 동안 가열하여 중합을 행하면, 리튬염 함유 겔 폴리머 전해질용 조성물이 겔화되면서 겔 폴리머 전해질이 제조된다. More specifically, the in-situ polymerization reaction in a lithium secondary battery is added to a predetermined amount of the polymerization initiator and the oligomer in a gel polymer electrolyte composition containing a lithium salt and mixed and then injected into a battery cell. After sealing the injection port of such a battery cell, the polymerization is carried out by heating at 60 ° C. to 80 ° C. for 1 to 20 hours, for example, to prepare a gel polymer electrolyte while gelling the composition for a lithium salt-containing gel polymer electrolyte.
본 발명의 일 실시예에 따른 상기 리튬 이차전지는 충전 전압이 3.0V 내지 5.0V 범위로, 일반전압 및 고전압 영역 모두에서 리튬 이차전지의 용량 특성이 우수하다.The lithium secondary battery according to an embodiment of the present invention has a charge voltage of 3.0V to 5.0V, excellent capacity characteristics of the lithium secondary battery in both the normal voltage and the high voltage region.
또한, 상기 본 발명의 겔 폴리머 전해질을 이용하여 코팅형 겔 폴리머 전해질을 구현하는 경우, 상기 겔 폴리머 전해질의 전체 중량에 대하여 10 중량% 내지 25 중량% 범위의 무기물 입자를 추가로 함유할 수 있다.In addition, when implementing the coating gel polymer electrolyte using the gel polymer electrolyte of the present invention, it may further contain inorganic particles in the range of 10% to 25% by weight relative to the total weight of the gel polymer electrolyte.
상기 무기물 입자는 폴리머 네트워크에 함침되어, 무기물 입자 간의 빈 공간에 의해 형성된 기공들을 통하여 고점도 용매가 잘 스며들도록 할 수 있다. 즉, 무기물 입자를 포함함으로써, 극성 물질 간의 친화력과 모세관 현상에 의해 고점도 용매에 대한 습윤성을 보다 향상되는 효과를 얻을 수 있다.The inorganic particles may be impregnated into the polymer network to allow the high viscosity solvent to penetrate well through the pores formed by the void space between the inorganic particles. That is, by including the inorganic particles, it is possible to obtain an effect of further improving the wettability to a high viscosity solvent by affinity between the polar substances and capillary phenomenon.
이러한 무기물 입자로는 유전율이 높고, 리튬 이차전지의 작동 전압 범위(예컨대, Li/Li+ 기준으로 0 내지 5V)에서 산화 및/또는 환원 반응이 일어나지 않는 무기물 입자를 사용할 수 있다. As such inorganic particles, inorganic particles having a high dielectric constant and which do not generate an oxidation and / or reduction reaction in an operating voltage range of the lithium secondary battery (for example, 0 to 5V based on Li / Li + ) may be used.
구체적으로, 상기 무기물 입자는 그 대표적인 예로서 유전율 상수가 5 이상인 BaTiO3, BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb1 - aLaaZr1 - bTibO3 (PLZT, 여기서, 0<a<1, 0<b<1임), Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), 하프니아(HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC 및 이들의 혼합체로부터 이루어진 군으로부터 선택된 단일물 또는 2종 이상의 혼합물을 들 수 있다. Specifically, the inorganic particles are BaTiO 3 , BaTiO 3 , Pb (Zr, Ti) O 3 (PZT), Pb 1 - a La a Zr 1 - b Ti b O 3 (PLZT) having a dielectric constant of 5 or more as a representative example thereof. , Where 0 <a <1, 0 <b <1, Pb (Mg 1/3 Nb 2/3 ) O 3 -PbTiO 3 (PMN-PT), Hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , SiC and a mixture selected from the group consisting of two or more thereof.
또한, 상기 무기물 입자 외에도 리튬 이온 전달 능력을 갖는 무기물 입자, 즉 리튬포스페이트 (Li3PO4), 리튬티타늄포스페이트 (LicTid(PO4)3, 0<d<2, 0<d<3), 리튬알루미늄티타늄포스페이트 (Lia1Alb1Tic1(PO4)3, 0<a1<2, 0<b1<1, 0<c1<3), 14Li2O-9Al2O3-38TiO2-39P2O5 등과 같은 (LiAlTiP)a2Ob2 계열 글래스(glass) (0<a2<4, 0<b2<13), 리튬란탄티타네이트 (Lia3Lab3TiO3, 0<a3<2, 0<b3<3), Li3 . 25Ge0 .25P0. 75S4 등과 같은 리튬게르마니움티오포스페이트 (Lia4Geb4Pc2Sd, 0<a4<4, 0<b4<1, 0<c2<1, 0<d<5), Li3N 등과 같은 리튬나이트라이드 (Lia5Nb5, 0<a5<4, 0<b5<2), Li3PO4-Li2S-SiS2 등과 같은 SiS2 계열 글래스 (Lia6Sib6Sc3, 0<a6<3, 0<b6<2, 0<c4<4), LiI-Li2S-P2S5 등과 같은 P2S5 계열 글래스 (Lia7Pb7Sc5, 0<a7<3, 0<b7<3, 0<c5<7) 또는 이들의 혼합물 등을 더 포함할 수 있다. In addition, in addition to the inorganic particles, inorganic particles having lithium ion transfer ability, that is, lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li c Ti d (PO 4 ) 3 , 0 <d <2, 0 <d <3 ), Lithium aluminum titanium phosphate (Li a1 Al b1 Ti c1 (PO 4 ) 3 , 0 <a1 <2, 0 <b1 <1, 0 <c1 <3), 14Li 2 O-9Al 2 O 3 -38TiO 2- (LiAlTiP) a2 O b2 series glass such as 39P 2 O 5 (0 <a2 <4, 0 <b2 <13), lithium lanthanum titanate (Li a3 La b3 TiO 3 , 0 <a3 <2, 0 <b3 <3), Li 3 . 25 Ge 0 .25 P 0. 75 S 4 Mani lithium germanium thiophosphate Titanium (Li a4 such as Ge b4 P c2 S d, 0 <a4 <4, 0 <b4 <1, 0 <c2 <1, 0 <d <5), lithium nitrides such as Li 3 N (Li a5 N b5 , 0 <a5 <4, 0 <b5 <2), and SiS 2 series glasses such as Li 3 PO 4 -Li 2 S-SiS 2 (Li a6 Si b6 S c3, 0 < a6 <3, 0 <b6 <2, 0 <c4 <4), LiI-Li 2 SP 2 S 5 , etc., such as P 2 S 5 based glass (Li a7 P b7 S c5, 0 <a7 <3, 0 <b7 <3, 0 <c5 <7) or mixtures thereof, and the like.
상기 무기물 입자들의 평균 입경은 겔 폴리머 전해질 내에 균일한 두께로 적절한 공극률을 가지도록 형성하기 위하여, 약 0.001 내지 10㎛ 범위인 것이 바람직하다. 만약, 평균 입경이 0.001㎛ 미만인 경우 분산성이 저하될 수 있고, 평균 입경이 10㎛를 초과하는 경우 다공성 코팅층의 두께가 증가할 수 있을 뿐만 아니라, 무기물 입자가 뭉치는 현상이 발생하여 겔 폴리머 전해질 밖으로 노출되면서 기계적 강도가 저하될 수 있다. The average particle diameter of the inorganic particles is preferably in the range of about 0.001 to 10 μm in order to have a proper porosity in a uniform thickness in the gel polymer electrolyte. If the average particle size is less than 0.001㎛ dispersibility may be lowered, if the average particle diameter is more than 10㎛ not only can increase the thickness of the porous coating layer, but also agglomeration of inorganic particles occurs gel gel electrolyte Exposure to the outside can lower the mechanical strength.
한편, 본 발명의 리튬 이차전지는 양극, 음극 및 양극과 음극 사이에 개재된 분리막으로 이루어진 전극 구조체에 본 발명의 겔 폴리머 전해질용 조성물을 주액한 후, 겔화하여 제조할 수 있다. 이때, 전극 구조체를 이루는 양극, 음극 및 분리막은 리튬 이차전지 제조에 통상적으로 사용되던 것들이 모두 사용될 수 있다.On the other hand, the lithium secondary battery of the present invention can be prepared by injecting the gel polymer electrolyte composition of the present invention in an electrode structure consisting of a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, and then gelled. At this time, the positive electrode, the negative electrode, and the separator constituting the electrode structure may be used all those conventionally used in the manufacture of a lithium secondary battery.
상기 양극은 양극 집전체 상에 양극 합제층을 형성하여 제조할 수 있다. 상기 양극 합제층은 양극활물질, 바인더, 도전재 및 용매 등을 포함하는 양극 슬러리를 양극 집전체 상에 코팅한 후, 건조 및 압연하여 형성할 수 있다.The positive electrode may be manufactured by forming a positive electrode mixture layer on a positive electrode current collector. The cathode mixture layer may be formed by coating a cathode slurry including a cathode active material, a binder, a conductive material, a solvent, and the like on a cathode current collector, followed by drying and rolling.
상기 양극 집전체는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 또는 알루미늄이나 스테인리스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면 처리한 것 등이 사용될 수 있다. The positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, the positive electrode current collector may be formed of stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. Surface treated with nickel, titanium, silver, or the like may be used.
상기 양극 활물질은 리튬의 가역적인 인터칼레이션 및 디인터칼레이션이 가능한 화합물로서, 구체적으로는 코발트, 망간, 니켈 또는 알루미늄과 같은 1종 이상의 금속과 리튬을 포함하는 리튬 복합금속 산화물을 포함할 수 있다. 보다 구체적으로, 상기 리튬 복합금속 산화물은 리튬-망간계 산화물(예를 들면, LiMnO2, LiMn2O4 등), 리튬-코발트계 산화물(예를 들면, LiCoO2 등), 리튬-니켈계 산화물(예를 들면, LiNiO2 등), 리튬-니켈-망간계 산화물(예를 들면, LiNi1 - YMnYO2(여기에서, 0<Y<1), LiMn2 - zNizO4(여기에서, 0＜Z＜2) 등), 리튬-니켈-코발트계 산화물(예를 들면, LiNi1 - Y1CoY1O2(여기에서, 0<Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo1-Y2MnY2O2(여기에서, 0<Y2<1), LiMn2 - z1Coz1O4(여기에서, 0＜Z1＜2) 등), 리튬-니켈-망간-코발트계 산화물(예를 들면, Li(NipCoqMnr1)O2(여기에서, 0＜p＜1, 0＜q＜1, 0＜r1＜1, p+q+r1=1) 또는 Li(Nip1Coq1Mnr2)O4(여기에서, 0＜p1＜2, 0＜q1＜2, 0＜r2＜2, p1+q1+r2=2) 등), 또는 리튬-니켈-코발트-전이금속(M) 산화물(예를 들면, Li(Nip2Coq2Mnr3MS2)O2(여기에서, M은 Al, Fe, V, Cr, Ti, Ta, Mg 및 Mo로 이루어지는 군으로부터 선택되고, p2, q2, r3 및 s2는 각각 자립적인 원소들의 원자분율로서, 0＜p2＜1, 0＜q2＜1, 0＜r3＜1, 0＜s2＜1, p2+q2+r3+s2=1이다) 등) 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 화합물이 포함될 수 있다. The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may specifically include a lithium composite metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. have. More specifically, the lithium composite metal oxide is a lithium-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4, etc.), lithium-cobalt oxide (eg, LiCoO 2, etc.), lithium-nickel oxide (for example, LiNiO 2 and the like), lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O 2 (where, 0 <Y <1), LiMn 2-z Ni z O 4 ( here, 0 <Z <2) and the like), lithium-nickel-cobalt oxide (e.g., LiNi 1-Y1 Co Y1 O 2 (here, 0 <Y1 <1) and the like), lithium-manganese-cobalt oxide (e. g., LiCo 1-Y2 Mn Y2 O 2 (here, 0 <Y2 <1), LiMn 2 - z1 Co z1 O 4 ( here, 0 <z1 <2) and the like), lithium-nickel Manganese-cobalt-based oxides (e.g., Li (Ni p Co q Mn r1 ) O 2 , where 0 <p <1, 0 <q <1, 0 <r1 <1, p + q + r1 = 1) or Li (Ni p1 Co q1 Mn r2 ) O 4 (where 0 <p1 <2, 0 <q1 <2, 0 <r2 <2, p1 + q1 + r2 = 2, etc.), or lithium- Nickel-cobalt-transition metal (M) oxide (e.g. Li (Ni p2 Co q2 Mn r3 M S2 ) O 2 (excitation Where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r3 and s2 are atomic fractions of freestanding elements, respectively, 0 <p2 <1, 0 <Q2 <1, 0 <r3 <1, 0 <s2 <1, p2 + q2 + r3 + s2 = 1), etc.), and any one or two or more of these compounds may be included.
이 중에서도 전지의 용량 특성 및 안정성을 높일 수 있다는 점에서 상기 리튬 복합금속 산화물은 LiCoO2, LiMnO2, LiNiO2, 리튬 니켈망간코발트 산화물 (예를 들면 Li(Ni1/3Mn1/3Co1/3)O2, Li(Ni0.6Mn0.2Co0.2)O2, Li(Ni0.5Mn0.3Co0.2)O2, Li(Ni0.7Mn0.15Co0.15)O2 및 Li(Ni0.8Mn0.1Co0.1)O2 등), 또는 리튬 니켈코발트알루미늄 산화물(예를 들면, Li(Ni0.8Co0.15Al0.05)O2 등) 등일 수 있다.Among them, the lithium composite metal oxide may be LiCoO 2 , LiMnO 2 , LiNiO 2 , or lithium nickel manganese cobalt oxide (for example, Li (Ni 1/3 Mn 1/3 Co 1). / 3) O 2, Li ( Ni 0.6 Mn 0.2 Co 0.2) O 2, Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , Li (Ni 0.7 Mn 0.15 Co 0.15 ) O 2, and Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 , or the like, or lithium nickel cobalt aluminum oxide (eg, Li (Ni 0.8 Co 0.15 Al 0.05 ) O 2 , and the like.
상기 양극 활물질은 양극 슬러리 중 고형분의 전체 중량을 기준으로 80 중량% 내지 99.5 중량%, 구체적으로 85 중량% 내지 95 중량%로 포함될 수 있다. The cathode active material may be included in an amount of 80 wt% to 99.5 wt%, specifically 85 wt% to 95 wt%, based on the total weight of solids in the cathode slurry.
상기 양극 활물질 함량이 80 중량% 이하인 경우 에너지 밀도가 낮아져 용량이 저하될 수 있다.When the positive electrode active material content is 80% by weight or less, the energy density may be lowered and thus the capacity may be lowered.
상기 바인더는 활물질과 도전재 등의 결합과 집전체에 대한 결합에 조력하는 성분으로서, 통상적으로 양극 슬러리 중 고형분의 전체 중량을 기준으로 1 내지 30 중량%로 첨가된다. 양극 슬러리 중 고형분의 전체 중량을 기준으로 1 중량부 내지 50 중량부, 더욱 상세하게는 3 중량부 내지 15 중량부로 첨가된다. 상기 바인더가 1 중량부 미만이면 전극활물질과 집전체와의 접착력이 불충분해질 수 있으며, 50 중량부를 초과하면 접착력은 향상되지만 그만큼 전극활물질의 함량이 감소하여 전지 용량이 낮아질 수 있다.The binder is a component that assists in bonding the active material and the conductive material to the current collector, and is generally added in an amount of 1 to 30 wt% based on the total weight of solids in the positive electrode slurry. 1 part by weight to 50 parts by weight, more specifically 3 parts by weight to 15 parts by weight, based on the total weight of solids in the positive electrode slurry. When the binder is less than 1 part by weight, the adhesive force between the electrode active material and the current collector may be insufficient. When the binder is more than 50 parts by weight, the adhesive force may be improved, but the content of the electrode active material may decrease, thereby lowering the battery capacity.
이러한 바인더의 예로는, 폴리비닐리덴플루오라이드, 폴리비닐알코올, 카르복시메틸셀룰로우즈(CMC), 전분, 히드록시프로필셀룰로우즈, 재생 셀룰로우즈, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 에틸렌-프로필렌-디엔 테르 폴리머(EPDM), 술폰화 EPDM, 스티렌-부타디엔 고무, 불소 고무, 다양한 공중합체 등을 들 수 있다.Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers, and the like.
또한, 상기 도전재는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 부여하는 물질로서, 양극 슬러리 중 고형분의 전체 중량을 기준으로 1 내지 20 중량%로 첨가될 수 있다.　In addition, the conductive material is a material that imparts conductivity without causing chemical change to the battery, and may be added in an amount of 1 to 20 wt% based on the total weight of solids in the cathode slurry.
이러한 도전재는 그 대표적인 예로 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼니스 블랙, 램프 블랙, 또는 서멀 블랙 등의 탄소 분말; 결정구조가 매우 발달된 천연 흑연, 인조흑연, 또는 그라파이트 등의 흑연 분말; 탄소 섬유나 금속 섬유 등의 도전성 섬유; 불화 카본, 알루미늄, 니켈 분말 등의 금속 분말; 산화아연, 티탄산 칼륨 등의 도전성 위스키; 산화티탄 등의 도전성 금속 산화물; 폴리페닐렌 유도체 등의 도전성 소재 등이 사용될 수 있으며, 현재 아세틸렌 블랙 계열 도전재 (Chevron Chemical Company 제조, 덴카 블랙(Denka Singapore Private Limited 제조), 또는 Gulf Oil Company 제조), 케첸 블랙(Ketjenblack), EC 계열(Armak Company 제조), 불칸 XC-72 (Cabot Company 제조) 및 수퍼(Super)-P(Timcal 제조) 등의 명칭으로 시판되고 있는 것을 사용할 수도 있다.Such conductive materials include carbon powders such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; Graphite powders such as natural graphite, artificial graphite, or graphite with very advanced crystal structure; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials, such as polyphenylene derivatives, may be used. Currently, acetylene black-based conductive materials (manufactured by Chevron Chemical Company, Denka Singapore Private Limited), or Gulf Oil Company), Ketjenblack, EC What is marketed by names, such as the series (made by Armak Company), Vulcan XC-72 (made by Cabot Company), and Super (P made by Timcal), can also be used.
상기 용매는 NMP(N-methyl-2-pyrrolidone) 등의 유기용매를 포함할 수 있으며, 상기 양극 활물질 및 선택적으로 바인더 및 도전재 등을 포함할 때 바람직한 점도가 되는 양으로 사용될 수 있다. 예를 들면, 양극 활물질, 및 선택적으로 바인더 및 도전재를 포함하는 슬러리 중의 고형분 농도가 10 중량% 내지 60 중량%, 바람직하게 20 중량% 내지 50 중량%가 되도록 포함될 수 있다.The solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount that becomes a desirable viscosity when including the positive electrode active material and optionally a binder and a conductive material. For example, the concentration of the solids in the slurry including the positive electrode active material and optionally the binder and the conductive material may be 10 wt% to 60 wt%, preferably 20 wt% to 50 wt%.
또한, 상기 음극은 음극 집전체 상에 음극 합제층을 형성하여 제조할 수 있다. 상기 음극 합제층은 음극활물질, 바인더, 도전재 및 용매 등을 포함하는 음극 슬러리를 음극 집전체 상에 코팅한 후, 건조 및 압연하여 형성할 수 있다.In addition, the negative electrode may be prepared by forming a negative electrode mixture layer on the negative electrode current collector. The negative electrode mixture layer may be formed by coating a negative electrode slurry including a negative electrode active material, a binder, a conductive material, a solvent, and the like on a negative electrode current collector, followed by drying and rolling.
상기 음극 집전체는 일반적으로 3 내지 500㎛의 두께를 가진다. 이러한 음극 집전체는, 당해 전지에 화학적 변화를 유발하지 않으면서 높은 도전성을 가지는 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 구리, 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 구리나 스테인리스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면 처리한 것, 알루미늄-카드뮴 합금 등이 사용될 수 있다. 또한, 양극 집전체와 마찬가지로, 표면에 미세한 요철을 형성하여 음극 활물질의 결합력을 강화시킬 수도 있으며, 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태로 사용될 수 있다.The negative electrode current collector generally has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like on the surface, aluminum-cadmium alloy and the like can be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
또한, 상기 음극활물질은 리튬 금속, 리튬 이온을 가역적으로 인터칼레이션/디인터칼레이션할 수 있는 탄소 물질, 금속 또는 이들 금속과 리튬의 합금, 금속 복합 산화물, 리튬을 도프 및 탈도프할 수 있는 물질, 및 전이 금속 산화물 전이 금속 산화물로 이루어진 군으로부터 선택된 적어도 하나 이상을 포함할 수 있다. In addition, the negative electrode active material may be lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal complex oxide, and may dope and undo lithium. At least one selected from the group consisting of materials, and transition metal oxide transition metal oxides.
상기 리튬 이온을 가역적으로 인터칼레이션/디인터칼레이션할 수 있는 탄소 물질로는, 리튬 이온 이차전지에서 일반적으로 사용되는 탄소계 음극 활물질이라면 특별히 제한 없이 사용할 수 있으며, 그 대표적인 예로는 결정질 탄소, 비정질 탄소 또는 이들을 함께 사용할 수 있다. 상기 결정질 탄소의 예로는 무정형, 판상, 인편상(flake), 구형 또는 섬유형의 천연 흑연 또는 인조 흑연과 같은 흑연을 들 수 있고, 상기 비정질 탄소의 예로는 소프트 카본(soft carbon: 저온 소성 탄소) 또는 하드 카본(hard carbon), 메조페이스 피치 탄화물, 소성된 코크스 등을 들 수 있다.As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material generally used in a lithium ion secondary battery may be used without particular limitation. Examples thereof include crystalline carbon, Amorphous carbons or these may be used together. Examples of the crystalline carbon include graphite such as amorphous, plate, flake, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (soft carbon) Or hard carbon, mesophase pitch carbide, calcined coke, or the like.
상기 금속 또는 이들 금속과 리튬의 합금으로는 Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al 및 Sn으로 이루어진 군에서 선택되는 금속 또는 이들 금속과 리튬의 합금이 사용될 수 있다.The metals or alloys of these metals with lithium include Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al And a metal selected from the group consisting of Sn or an alloy of these metals with lithium may be used.
상기 금속 복합 산화물로는 PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, LixFe2O3(0≤x≤1), LixWO2(0≤x≤1), 및 SnxMe1 -xMe'yOz (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, 주기율표의 1족, 2족, 3족 원소, 할로겐; 0<x≤1; 1≤y≤3; 1≤z≤8) 로 이루어진 군에서 선택되는 것이 사용될 수 있다.The metal complex oxide may include PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 , Bi 2 O 5 , Li x Fe 2 O 3 (0 ≦ x ≦ 1), Li x WO 2 (0 ≦ x ≦ 1), and Sn x Me 1- x Me ' y O z (Me: Mn, Fe Me ': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 <x≤1;1≤y≤3; 1≤z≤8 Any one selected from the group can be used.
상기 리튬을 도프 및 탈도프할 수 있는 물질로는 Si, SiOx(0 < x < 2), Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), Sn, SnO2, Sn-Y(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Y로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택될 수 있다.Examples of the material capable of doping and undoping lithium include Si, SiO x (0 <x <2), Si-Y alloys (wherein Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, Is an element selected from the group consisting of rare earth elements and combinations thereof, not Si), Sn, SnO 2 , Sn-Y (Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth) An element selected from the group consisting of elements and combinations thereof, and not Sn; and at least one of these and SiO 2 may be mixed and used. As the element Y, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.
상기 전이 금속 산화물로는 리튬 함유 티타늄 복합 산화물(LTO), 바나듐 산화물, 리튬 바나듐 산화물 등을 들 수 있다.Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, and the like.
상기 음극 활물질은 음극 슬러리 중 고형분의 전체 중량을 기준으로 80 중량% 내지 99 중량%로 포함될 수 있다.The negative active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of solids in the negative electrode slurry.
상기 바인더는 도전재, 활물질 및 집전체 간의 결합에 조력하는 성분으로서, 통상적으로 음극 슬러리 중 고형분 전체 중량을 기준으로 1 내지 30 중량%로 첨가된다.　이러한 바인더의 예로는, 폴리비닐리덴플루오라이드(PVDF), 폴리비닐알코올, 카르복시메틸셀룰로우즈(CMC), 전분, 히드록시프로필셀룰로우즈, 재생 셀룰로우즈, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 에틸렌-프로필렌-디엔 폴리머(EPDM), 술폰화-EPDM, 스티렌-부타디엔 고무, 불소 고무, 이들의 다양한 공중합체 등을 들 수 있다.The binder is a component that assists in the bonding between the conductive material, the active material and the current collector, and is typically added in an amount of 1 to 30 wt% based on the total weight of solids in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoro Low ethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, and the like.
상기 도전재는 양극 제조 시 사용된 것과 동일한 물질을 사용할 수 있으며, 음극 슬러리 중 고형분의 전체 중량을 기준으로 1 내지 20 중량%로 첨가될 수 있다.　The conductive material may be the same material as used in the production of the positive electrode, it may be added in 1 to 20% by weight based on the total weight of solids in the negative electrode slurry.
상기 용매는 물 또는 NMP(N-methyl-2-pyrrolidone) 등의 유기용매를 포함할 수 있으며, 상기 음극 활물질, 및 선택적으로 바인더 및 도전재 등을 포함할 때 바람직한 점도가 되는 양으로 사용될 수 있다. 예를 들면, 음극 활물질, 및 선택적으로 바인더 및 도전재를 포함하는 고형분의 농도가 50 중량% 내지 95 중량%, 바람직하게 70 중량% 내지 90 중량%가 되도록 포함될 수 있다.The solvent may include an organic solvent such as water or NMP (N-methyl-2-pyrrolidone), and may be used in an amount that becomes a desirable viscosity when including the negative electrode active material, and optionally a binder and a conductive material. . For example, the concentration of the negative electrode active material and, optionally, the solid content including the binder and the conductive material may be 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.
또한, 분리막으로는 종래에 분리막으로 사용된 통상적인 다공성 고분자 필름, 예를 들어 에틸렌 단독중합체, 프로필렌 단독중합체, 에틸렌/부텐 공중합체, 에틸렌/헥센 공중합체 및 에틸렌/메타크릴레이트 공중합체 등과 같은 폴리올레핀계 고분자로 제조한 다공성 고분자 필름을 단독으로 또는 이들을 적층하여 사용할 수 있으며, 또는 통상적인 다공성 부직포, 예를 들어 고융점의 유리 섬유, 폴리에틸렌테레프탈레이트 섬유 등으로 된 부직포를 사용할 수 있으나, 이에 한정되는 것은 아니다.In addition, as the separator, conventional porous polymer films conventionally used as separators, for example, polyolefins such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer, etc. The porous polymer film made of the polymer may be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used. It is not.
본 발명의 리튬 이차전지의 외형은 특별한 제한이 없으나, 캔을 사용한 원통형, 각형, 파우치(pouch)형 또는 코인(coin)형 등이 될 수 있다.The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, square, pouch type, or coin type using a can.
이하, 본 발명을 구체적으로 설명하기 위해 실시예를 들어 상세하게 설명하기로 한다. 그러나 본 발명에 따른 실시예는 여러 가지 다른 형태로 변형될 수 있으며, 본 발명의 범위가 아래에서 상술하는 실시예에 한정되는 것으로 해석되어서는 안 된다. 본 발명의 실시예는 당업계에서 평균적인 지식을 가진 자에게 본 발명을 보다 완전하게 설명하기 위해서 제공되는 것이다.Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.
실시예Example
<리튬 이차전지의 제조><Production of Lithium Secondary Battery>
실시예 1Example 1
(겔 폴리머 전해질용 조성물 제조)(Manufacture of composition for gel polymer electrolyte)
1M LiPF6가 용해된 비수성 유기용매 (에틸렌 카보네이트(EC):에틸메틸카보네이트(EMC)= 3:7 부피비) 94.8g에 상기 화학식 1a-1의 화합물 (n=10, 중량평균분자량(Mw): 3,000 g/mol) 5g 및 중합개시제로서 디메틸 2,2'-아조비스(2-메틸프로피오네이트) (CAS No. 2589-57-3) 0.2g을 첨가하여 겔 폴리머 전해질용 조성물을 제조하였다. 94.8 g of a non-aqueous organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which 1 M LiPF 6 was dissolved (n = 10, weight average molecular weight (Mw)) : 3,000 g / mol) 5g and 0.2g of dimethyl 2,2'-azobis (2-methylpropionate) (CAS No. 2589-57-3) were added as a polymerization initiator to prepare a composition for a gel polymer electrolyte. .
(리튬 이차전지의 제조)(Manufacture of Lithium Secondary Battery)
양극 활물질로 (LiNi1 / 3Co1 / 3Mn1 / 3O2; NCM) 94 중량%, 도전재로 카본 블랙(carbon black) 3 중량%, 바인더로 폴리비닐리덴플루오라이드(PVDF) 3 중량%를 용매인 N-메틸-2-피롤리돈(NMP)에 첨가하여 양극 활물질 슬러리 (고형분 함량 50%)를 제조하였다. 상기 양극 활물질 슬러리를 두께가 20㎛ 정도의 양극 집전체인 알루미늄(Al) 박막에 도포하고, 건조하여 양극을 제조한 후, 롤 프레스(roll press)를 실시하여 양극을 제조하였다.As a cathode active material (LiNi 1/3 Co 1/ 3 Mn 1/3 O 2; NCM) 94 % by weight, of a conductive material of carbon black (carbon black) 3% by weight of polyvinyl a binder fluoride (PVDF) 3 parts by weight % Was added to the solvent N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode active material slurry (50% solids content). The positive electrode active material slurry was applied to an aluminum (Al) thin film, which is a positive electrode current collector having a thickness of about 20 μm, dried to prepare a positive electrode, and then roll rolled to prepare a positive electrode.
음극 활물질로 탄소 분말, 바인더로 PVDF, 도전재로 카본 블랙(carbon black)을 각각 96 중량%, 3 중량% 및 1 중량%로 하여 용매인 NMP에 첨가하여 음극 활물질 슬러리 (고형분 함량 80%)를 제조하였다. 상기 음극 활물질 슬러리를 두께가 10㎛의 음극 집전체인 구리(Cu) 박막에 도포하고, 건조하여 음극을 제조한 후, 롤 프레스(roll press)를 실시하여 음극을 제조하였다.Carbon powder as a negative electrode active material, PVDF as a binder and carbon black as a conductive material were added to NMP, which is 96% by weight, 3% by weight, and 1% by weight, respectively, to prepare a negative electrode active material slurry (solid content 80%). Prepared. The negative electrode active material slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 μm, and dried to prepare a negative electrode, followed by roll press, to prepare a negative electrode.
상기 양극, 음극 및 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막을 순차적으로 적층하여 전극조립체를 제조하였다. An electrode assembly was manufactured by sequentially stacking a separator consisting of the anode, the cathode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP).
상기 양극, 음극 및 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막을 이용하여 전극조립체를 제조하고, 이를 전지케이스에 수납하고 상기 제조된 겔 폴리머 전해질용 조성물을 주액하였다.An electrode assembly was prepared using a separator consisting of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and housed in a battery case, and injected the prepared gel polymer electrolyte composition. .
이어서, 2일 동안 상온에서 저장한 다음, 65℃에서 5시간 가열하여 열 중합된 겔 폴리머 전해질을 포함하는 리튬 이차전지를 제조하였다.Subsequently, after storing at room temperature for 2 days, a lithium secondary battery comprising a gel polymer electrolyte thermally polymerized by heating at 65 ° C. for 5 hours was prepared.
실시예 2Example 2
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 89.8g에 상기 화학식 1a-1의 화합물 10g 및 중합개시제 0.2g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.In preparing the gel polymer electrolyte composition, the gel polymer electrolyte composition was prepared in the same manner as in Example 1, except that 10g of the compound of Formula 1a-1 and 0.2g of a polymerization initiator were added to 89.8g of the non-aqueous organic solvent. And a secondary battery comprising a gel polymer electrolyte using the same was prepared.
실시예 3.Example 3.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 98.98g에 상기 화학식 1a-1의 화합물 1g 및 중합개시제 0.02g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.In preparing the gel polymer electrolyte composition, the gel polymer electrolyte composition was prepared in the same manner as in Example 1, except that 1 g of the compound of Formula 1a-1 and 0.02 g of a polymerization initiator were added to 98.98 g of the non-aqueous organic solvent. And a secondary battery comprising a gel polymer electrolyte using the same was prepared.
실시예 4.Example 4.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 94.8g에 상기 화학식 1a-1의 화합물 (중량평균분자량(Mw): 1,000 g/mol) 5g 및 중합개시제 0.2g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.When preparing the gel polymer electrolyte composition, except that 5 g of the compound of Formula 1a-1 (weight average molecular weight (Mw): 1,000 g / mol) and 0.2 g of a polymerization initiator were added to 94.8 g of the non-aqueous organic solvent. In the same manner as in Example 1, a secondary battery including a gel polymer electrolyte composition and a gel polymer electrolyte using the same was manufactured.
실시예 5.Example 5.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 78g에 상기 화학식 1a-1의 화합물 20g 및 중합개시제 2g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.When preparing a composition for a gel polymer electrolyte, a composition for a gel polymer electrolyte and a composition thereof in the same manner as in Example 1 except that 20 g of the compound of Formula 1a-1 and 2 g of a polymerization initiator are added to 78 g of a non-aqueous organic solvent. A secondary battery including the used gel polymer electrolyte was prepared.
실시예 6.Example 6.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 94.8g에 상기 화학식 1a-1의 화합물 (중량평균분자량(Mw): 10,000 g/mol) 5g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.When preparing a composition for a gel polymer electrolyte, 94.8 g of the non-aqueous organic solvent was added to 54.8 g of the compound of Formula 1a-1 (weight average molecular weight (Mw): 10,000 g / mol) as in Example 1 above. By the method of preparing a composition for a gel polymer electrolyte and a secondary battery comprising a gel polymer electrolyte using the same.
실시예 7.Example 7.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 99.68g에 상기 화학식 1a-1의 화합물 (n=10, 중량평균분자량(Mw): 3,000 g/mol) 0.3g 및 중합개시제 0.02g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.To prepare a gel polymer electrolyte composition, 0.3g of a compound of Formula 1a-1 (n = 10, weight average molecular weight (Mw): 3,000 g / mol) and 0.02g of a polymerization initiator were added to 99.68g of a non-aqueous organic solvent. A secondary battery including a gel polymer electrolyte composition and a gel polymer electrolyte using the same was prepared in the same manner as in Example 1 except that.
실시예 8.Example 8.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 70g에 상기 화학식 1a-1의 화합물 (n=10, 중량평균분자량(Mw): 3,000 g/mol) 25g 및 중합개시제 5g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.In preparing the gel polymer electrolyte composition, 25 g of the compound of Formula 1a-1 (n = 10, weight average molecular weight (Mw): 3,000 g / mol) and 5 g of a polymerization initiator were added to 70 g of the non-aqueous organic solvent. In the same manner as in Example 1, a gel polymer electrolyte composition and a secondary battery including the gel polymer electrolyte using the same were prepared.
실시예 9.Example 9.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 94.8g에 상기 화학식 1a-1의 화합물 (n=10, 중량평균분자량(Mw): 500 g/mol) 5g 및 중합개시제 0.2g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.In preparing the gel polymer electrolyte composition, 5 g of the compound of Formula 1a-1 (n = 10, Mw: 500 g / mol) and 0.2 g of a polymerization initiator were added to 94.8 g of the non-aqueous organic solvent. A secondary battery including a gel polymer electrolyte composition and a gel polymer electrolyte using the same was prepared in the same manner as in Example 1 except for the above.
실시예 10.Example 10.
겔 폴리머 전해질용 조성물 제조 시에, 비수성 유기용매 94.8g에 상기 화학식 1a-1의 화합물 (n=10, 중량평균분자량(Mw): 20,000 g/mol) 5g 및 중합개시제 0.2g을 첨가하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물 및 이를 이용한 겔 폴리머 전해질을 포함하는 이차전지를 제조하였다.To prepare a gel polymer electrolyte composition, 5 g of the compound of Formula 1a-1 (n = 10, weight average molecular weight (Mw): 20,000 g / mol) and 0.2 g of a polymerization initiator were added to 94.8 g of the non-aqueous organic solvent. A secondary battery including a gel polymer electrolyte composition and a gel polymer electrolyte using the same was prepared in the same manner as in Example 1 except for the above.
비교예Comparative example 1. One.
(비수전해액 제조)(Non-aqueous electrolyte preparation)
1M LiPF6를 비수성 유기용매 (에틸렌 카보네이트(EC):에틸메틸카보네이트(EMC)= 3:7 부피비)에 용해하여 비수전해액을 제조하였다.1 M LiPF 6 was dissolved in a non-aqueous organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 by volume) to prepare a non-aqueous electrolyte.
(리튬 이차전지의 제조)(Manufacture of Lithium Secondary Battery)
양극 활물질로 (LiNi1 / 3Co1 / 3Mn1 / 3O2; NCM) 94 중량%, 도전재로 카본 블랙(carbon black) 3 중량%, 바인더로 폴리비닐리덴플루오라이드(PVDF) 3 중량%를 용매인 N-메틸-2-피롤리돈(NMP)에 첨가하여 양극 활물질 슬러리 (고형분 함량 50%)를 제조하였다. 상기 양극 활물질 슬러리를 두께가 20㎛ 정도의 양극 집전체인 알루미늄(Al) 박막에 도포하고, 건조하여 양극을 제조한 후, 롤 프레스(roll press)를 실시하여 양극을 제조하였다.As a cathode active material (LiNi 1/3 Co 1/ 3 Mn 1/3 O 2; NCM) 94 % by weight, of a conductive material of carbon black (carbon black) 3% by weight of polyvinyl a binder fluoride (PVDF) 3 parts by weight % Was added to the solvent N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode active material slurry (50% solids content). The positive electrode active material slurry was applied to an aluminum (Al) thin film, which is a positive electrode current collector having a thickness of about 20 μm, dried to prepare a positive electrode, and then roll rolled to prepare a positive electrode.
음극 활물질로 탄소 분말, 바인더로 PVDF, 도전재로 카본 블랙(carbon black)을 각각 96 중량%, 3 중량% 및 1 중량%로 하여 용매인 NMP에 첨가하여 음극 활물질 슬러리 (고형분 함량 80%)를 제조하였다. 상기 음극 활물질 슬러리를 두께가 10㎛의 음극 집전체인 구리(Cu) 박막에 도포하고, 건조하여 음극을 제조한 후, 롤 프레스(roll press)를 실시하여 음극을 제조하였다.Carbon powder as a negative electrode active material, PVDF as a binder and carbon black as a conductive material were added to NMP, which is 96% by weight, 3% by weight, and 1% by weight, respectively, to prepare a negative electrode active material slurry (solid content 80%). Prepared. The negative electrode active material slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 μm, and dried to prepare a negative electrode, followed by roll press, to prepare a negative electrode.
상기 양극, 음극 및 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막을 순차적으로 적층하여 전극조립체를 제조하였다. An electrode assembly was manufactured by sequentially stacking a separator consisting of the anode, the cathode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP).
상기 양극, 음극 및 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막을 이용하여 전극조립체를 제조하고, 이를 전지케이스에 수납하고 상기 제조된 비수전해액을 주액하여 리튬 이차전지(Full cell)를 제조하였다.An electrode assembly is manufactured by using a separator formed of three layers of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and stored in a battery case, followed by pouring the prepared nonaqueous electrolyte into a lithium secondary battery. (Full cell) was prepared.
비교예Comparative example 2. 2.
(겔 폴리머 전해질용 조성물 제조)(Manufacture of composition for gel polymer electrolyte)
1M LiPF6가 용해된 비수성 유기용매 (에틸렌 카보네이트(EC):에틸메틸카보네이트(EMC)= 3:7 부피비) 95g에 하기 화학식 3으로 표시되는 ETPTA (ethoxylated tri-methylolpropane triacrylate) 올리고머 5g 및 중합개시제로서 디메틸 2,2'-아조비스(2-메틸프로피오네이트) (CAS No. 2589-57-3) 0.2g을 첨가하여 겔 폴리머 전해질용 조성물을 제조하였다. 5 g of a non-aqueous organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which 1 M LiPF 6 is dissolved, 5 g of an ethoxylated tri-methylolpropane triacrylate (ETPTA) oligomer represented by the following formula (3) and a polymerization initiator As a composition, 0.2 g of dimethyl 2,2'-azobis (2-methylpropionate) (CAS No. 2589-57-3) was added to prepare a gel polymer electrolyte composition.
[화학식 3][Formula 3]
Figure PCTKR2018000647-appb-I000013
Figure PCTKR2018000647-appb-I000013
(리튬 이차전지의 제조)(Manufacture of Lithium Secondary Battery)
상기 제조된 겔 폴리머 전해질용 조성물을 이용하는 것을 제외하고는 상기 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질을 포함하는 리튬 이차전지를 제조하였다.A lithium secondary battery including a gel polymer electrolyte was manufactured in the same manner as in Example 1 except for using the prepared gel polymer electrolyte composition.
하기 표 1에 실시예 1 내지 10의 겔 폴리머 전해질용 조성물과 비교예 1 및 2의 겔 폴리머 조성물용 조성물의 구성을 정리하였다.In Table 1 below, the compositions of the gel polymer electrolyte compositions of Examples 1 to 10 and the gel polymer compositions of Comparative Examples 1 and 2 are summarized.
Figure PCTKR2018000647-appb-T000001
Figure PCTKR2018000647-appb-T000001
실험예Experimental Example
실험예Experimental Example 1: 고온 안정성 평가(1) 1: High temperature stability evaluation (1)
실시예 1 및 2의 겔 폴리머 전해질을 포함하는 이차전지와 비교예 1의 비수전해액을 포함하는 이차전지 및 비교예 2의 겔 폴리머 전해질을 포함하는 이차전지를 각각 SOC 100% 상태에서 고온 저장(60℃)한 후, 두께 증가율(%)을 측정하였다. 그 결과를 도 1에 나타내었다.The secondary batteries including the gel polymer electrolytes of Examples 1 and 2, the secondary battery including the nonaqueous electrolyte of Comparative Example 1, and the secondary battery including the gel polymer electrolyte of Comparative Example 2 were stored at a high temperature of SOC at 100%, respectively. Thickness increase rate (%) was measured. The results are shown in FIG.
도 1의 두께 증가율(%)을 살펴보면, 본 발명의 실시예에 따른 올리고머를 포함하는 겔 폴리머 전해질용 조성물을 사용한 실시예 1 및 2의 이차전지의 경우, 올리고머를 포함하지 않은 비수전해액을 사용한 비교예 1의 이차전지와 겔 폴리머 전해질용 조성물을 사용한 비교예 2의 이차전지에 비해 60℃에서 4주간 이후부터 두께 증가율이 현저히 감소함을 확인할 수 있다.Looking at the thickness increase rate (%) of Figure 1, in the case of secondary batteries of Examples 1 and 2 using the composition for a gel polymer electrolyte containing an oligomer according to an embodiment of the present invention, the comparison using a non-aqueous electrolyte containing no oligomer Compared with the secondary battery of Comparative Example 2 using the composition for the secondary battery and the gel polymer electrolyte of Example 1, it can be seen that the thickness increase rate is significantly reduced after 4 weeks at 60 ° C.
실험예Experimental Example 2: 고온 안정성 평가(2) 2: high temperature stability evaluation (2)
실시예 3 내지 10에서 제조한 리튬 이차전지를 0.1C rate로 3시간 충전하였다. 이어서, 탈가스 (degas)/재밀봉 (reseal)하고 실온에서 0.2C로 4.15V까지 정전류/정전압조건으로 충전하고, 0.2C로 3.0V까지 정전류 조건으로 방전하여 초기 충방전을 수행하였다. 초기 충방전 후, 각각 4.15V로 충전하고, 60℃에서 6주 동안 저장(SOC (state of charge) 100%)하면서, 0 주차 대비 6주 차의 cell의 용량 유지율(%) 및 두께 변화율(swelling)을 측정하였다.The lithium secondary batteries prepared in Examples 3 to 10 were charged at 0.1C rate for 3 hours. Subsequently, degas / reseal and charge at a constant temperature / constant voltage condition up to 4.15V at 0.2C at room temperature, and discharge under constant current condition up to 3.0V at 0.2C were performed for initial charge and discharge. After initial charging and discharging, each was charged to 4.15V and stored at 60 ° C. for 6 weeks (state of charge (100%)), while maintaining capacity (%) and thickness change rate of the cell at week 6 to 0 parking. ) Was measured.
그 결과를 하기 표 2에 나타내었다.The results are shown in Table 2 below.
Figure PCTKR2018000647-appb-T000002
Figure PCTKR2018000647-appb-T000002
상기 표 2에 나타낸 바와 같이, 실시예 3 내지 6에서 제조한 리튬 이차전지는 고온 저장 후 용량 유지율이 약 94% 이상이고, 고온 저장 후 두께 증가율은 약 7.5% 이하인 것을 알 수 있다.As shown in Table 2, the lithium secondary batteries prepared in Examples 3 to 6 have a capacity retention rate of about 94% or more after high temperature storage, and a thickness increase rate of about 7.5% or less after high temperature storage.
한편, 올리고머가 소량 포함된 겔 폴리머 전해질용 조성물을 구비한 실시예 7의 리튬 이차전지는 겔 화가 어려워 성능 테스트가 불가하였다.On the other hand, the lithium secondary battery of Example 7 having a composition for gel polymer electrolyte containing a small amount of oligomer was difficult to gel performance test was not possible.
또한, 올리고머가 과량 포함된 겔 폴리머 전해질을 구비한 실시예 8의 리튬 이차전지는 전해질 내의 저항 증가로 인하여 고온 저장 후 용량 유지율은 90.1% 이상이고, 고온 저장 후 두께 증가율은 15.9%로 실시예 3 내지 6에서 제조한 리튬 이차전지 대비 열화된 것을 알 수 있다.In addition, the lithium secondary battery of Example 8 having an excess of oligomer-containing gel polymer electrolyte had a capacity retention of at least 90.1% after high temperature storage and a thickness increase rate of 15.9% after high temperature storage due to an increase in resistance in the electrolyte. It can be seen that the degradation compared to the lithium secondary battery manufactured in 6 to 6.
또한, 중량평균분자량이 낮은 올리고머를 포함하는 겔 폴리머 전해질을 구비한 실시예 9의 리튬 이차전지의 고온 저장 후 용량 유지율은 91% 이상이고, 고온 저장 후 두께 증가율은 10.8%로 동일 조건의 겔 고분자 반응에서 반응 열위를 일으켜, 실시예 3 내지 6에서 제조한 리튬 이차전지 대비 열화된 것을 알 수 있다.In addition, the capacity retention rate of the lithium secondary battery of Example 9 having a gel polymer electrolyte containing an oligomer having a low weight average molecular weight after the high temperature storage capacity is 91% or more, the thickness increase rate after high temperature storage is 10.8% gel polymer of the same conditions It can be seen that the reaction inferior in the reaction, deteriorated compared to the lithium secondary battery prepared in Examples 3 to 6.
또한, 중량평균분자량이 높은 올리고머를 포함하는 겔 폴리머 전해질을 구비한 실시예 10의 리튬 이차전지는 겔 폴리머 전해질용 조성물의 점도 증가로 웨팅 효과가 저하되기 때문에, 실시예 3 내지 6에서 제조한 리튬 이차전지 대비 열화된 것을 알 수 있다.In addition, the lithium secondary battery of Example 10 having a gel polymer electrolyte containing an oligomer having a high weight average molecular weight has a lowering of the wetting effect due to an increase in the viscosity of the gel polymer electrolyte composition. It can be seen that the secondary battery is degraded.

Claims (11)

  1. 리튬염; Lithium salts;
    비수성 유기용매;Non-aqueous organic solvents;
    하기 화학식 1로 표시되는 올리고머; 및An oligomer represented by Formula 1 below; And
    중합개시제;를 포함하는 것인 겔 폴리머 전해질용 조성물.A composition for gel polymer electrolyte comprising a polymerization initiator.
    [화학식 1][Formula 1]
    Figure PCTKR2018000647-appb-I000014
    Figure PCTKR2018000647-appb-I000014
    상기 화학식 1에서,In Chemical Formula 1,
    R1 내지 R3는 각각 독립적으로 불소로 치환 또는 비치환된 탄소수 1 내지 4의 알킬렌기이고, R 1 to R 3 are each independently an alkylene group having 1 to 4 carbon atoms unsubstituted or substituted with fluorine,
    R4 및 R5는 각각 독립적으로 지방족 탄화수소기 또는 방향족 탄화수소기이며,R 4 and R 5 are each independently an aliphatic hydrocarbon group or an aromatic hydrocarbon group,
    R6 및 R7은 각각 독립적으로 탄소수 1 내지 10의 알킬기 또는
    Figure PCTKR2018000647-appb-I000015
    이고, 상기 R8 및 R9는 각각 독립적으로 탄소수 1 내지 10의 알킬기 또는
    Figure PCTKR2018000647-appb-I000016
    이며,     R 6 and R 7 are each independently an alkyl group having 1 to 10 carbon atoms or
    Figure PCTKR2018000647-appb-I000015
    R 8 and R 9 are each independently an alkyl group having 1 to 10 carbon atoms or
    Figure PCTKR2018000647-appb-I000016
    Is,
    이때 R10은 지방족 탄화수소기 또는 방향족 탄화수소기이고,Wherein R 10 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group,
    R11은 탄소수 1 내지 3의 알킬렌기이며, R 11 is an alkylene group having 1 to 3 carbon atoms,
    R12는 수소 또는 탄소수 1 내지 2의 알킬기이고,R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms,
    n은 1 내지 70 중 어느 하나의 정수이고,n is an integer of any one of 1 to 70,
    m은 1 내지 3 중 어느 하나의 정수이다.m is an integer of any one of 1-3.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 화학식 1로 표시되는 올리고머에서, In the oligomer represented by Formula 1,
    상기 지방족 탄화수소기는 치환 또는 비치환된 탄소수 4 내지 20의 시클로알킬렌기; 이소시아네이트기(NCO)를 함유하는 치환 또는 비치환된 탄소수 4 내지 20의 시클로알킬렌기; 치환 또는 비치환된 탄소수 4 내지 20의 시클로알케닐렌기; 및 치환 또는 비치환된 탄소수 2 내지 20의 헤테로시클로알킬렌기로 이루어진 군으로부터 선택된 적어도 하나 이상의 지환족 탄화수소기, 또는 치환 또는 비치환된 탄소수 1 내지 20의 알킬렌기; 이소시아네이트기(NCO)를 함유하는 치환 또는 비치환된 탄소수 1 내지 20의 알킬렌기; 치환 또는 비치환된 탄소수 1 내지 20의 알콕실렌기; 치환 또는 비치환된 탄소수 2 내지 20의 알케닐렌기; 및 치환 또는 비치환된 탄소수 2 내지 20의 알키닐렌기로 이루어진 군으로부터 선택된 적어도 하나 이상의 선형 탄화수소기이고,The aliphatic hydrocarbon group may be substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms; Substituted or unsubstituted C4-C20 cycloalkylene group containing an isocyanate group (NCO); A substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms; And at least one alicyclic hydrocarbon group selected from the group consisting of a substituted or unsubstituted heterocycloalkylene group having 2 to 20 carbon atoms, or a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms; Substituted or unsubstituted C1-C20 alkylene group containing an isocyanate group (NCO); A substituted or unsubstituted alkoxylene group having 1 to 20 carbon atoms; A substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms; And at least one linear hydrocarbon group selected from the group consisting of a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms,
    상기 방향족 탄화수소기는 치환 또는 비치환된 탄소수 6 내지 20의 아릴렌기; 또는 치환 또는 비치환된 탄소수 2 내지 20의 헤테로아릴렌기인 것인 겔 폴리머 전해질용 조성물.The aromatic hydrocarbon group is substituted or unsubstituted arylene group having 6 to 20 carbon atoms; Or a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms.
  3. 청구항 1에 있어서, The method according to claim 1,
    상기 화학식 1로 표시되는 올리고머는 하기 화학식 1a로 표시되는 올리고머를 포함하는 것인 겔 폴리머 전해질용 조성물:The oligomer represented by the formula (1) is a gel polymer electrolyte composition comprising an oligomer represented by the formula (1a):
    [화학식 1a][Formula 1a]
    Figure PCTKR2018000647-appb-I000017
    Figure PCTKR2018000647-appb-I000017
    상기 화학식 1a에서,In Chemical Formula 1a,
    R4 및 R5는 각각 독립적으로 지방족 탄화수소기이며,R 4 and R 5 are each independently an aliphatic hydrocarbon group,
    R8 및 R9는 각각 독립적으로
    Figure PCTKR2018000647-appb-I000018
    이며,     R 8 and R 9 are each independently
    Figure PCTKR2018000647-appb-I000018
    Is,
    R10은 지방족 탄화수소기이고, R 10 is an aliphatic hydrocarbon group,
    R11은 탄소수 1 내지 3의 알킬렌기이며, R 11 is an alkylene group having 1 to 3 carbon atoms,
    R12는 수소 또는 탄소수 1 내지 2의 알킬기이고,R 12 is hydrogen or an alkyl group having 1 to 2 carbon atoms,
    n은 10 내지 20 중 어느 하나의 정수이고,n is an integer of any one of 10 to 20,
    m은 1 내지 2 중 어느 하나의 정수다.m is an integer of any one of 1-2.
  4. 청구항 3에 있어서, The method according to claim 3,
    상기 화학식 1a로 표시되는 올리고머는 하기 화학식 1a-1로 표시되는 올리고머를 포함하는 것인 겔 폴리머 전해질용 조성물: The oligomer represented by the formula (1a) is a composition for a gel polymer electrolyte comprising an oligomer represented by the formula (1a-1):
    [화학식 1a-1][Formula 1a-1]
    Figure PCTKR2018000647-appb-I000019
    Figure PCTKR2018000647-appb-I000019
    상기 화학식 1a-1에서,  In Chemical Formula 1a-1,
    n은 10 내지 20 중 어느 하나의 정수이다.n is an integer of any one of 10-20.
  5. 청구항 1에 있어서,The method according to claim 1,
    상기 화학식 1로 표시되는 올리고머는 겔 폴리머 전해질용 조성물 전체 중량을 기준으로 0.5 중량% 내지 20 중량%로 포함되는 것인 겔 폴리머 전해질용 조성물.The oligomer represented by the formula (1) is a gel polymer electrolyte composition comprising 0.5 wt% to 20 wt% based on the total weight of the gel polymer electrolyte composition.
  6. 청구항 5에 있어서,The method according to claim 5,
    상기 화학식 1로 표시되는 올리고머는 겔 폴리머 전해질용 조성물 전체 중량을 기준으로 0.5 중량% 내지 10 중량%로 포함되는 것인 겔 폴리머 전해질용 조성물.The oligomer represented by the formula (1) is a gel polymer electrolyte composition comprising 0.5 wt% to 10 wt% based on the total weight of the gel polymer electrolyte composition.
  7. 청구항 1에 있어서,The method according to claim 1,
    상기 화학식 1로 표시되는 올리고머의 중량평균분자량(MW)은 1,000 g/mol 내지 10,000 g/mol인 것인 겔 폴리머 전해질용 조성물.The weight average molecular weight (MW) of the oligomer represented by the formula (1) is a gel polymer electrolyte composition that is 1,000 g / mol to 10,000 g / mol.
  8. 청구항 7에 있어서,The method according to claim 7,
    상기 화학식 1로 표시되는 올리고머의 중량평균분자량(MW)은 3,000 g/mol 내지 8,000 g/mol인 것인 겔 폴리머 전해질용 조성물.The weight average molecular weight (MW) of the oligomer represented by the formula (1) is a composition for a gel polymer electrolyte is 3,000 g / mol to 8,000 g / mol.
  9. 청구항 8에 있어서,The method according to claim 8,
    상기 화학식 1로 표시되는 올리고머의 중량평균분자량(MW)은 3,000 g/mol 내지 5,000 g/mol인 것인 겔 폴리머 전해질용 조성물.The weight average molecular weight (MW) of the oligomer represented by the formula (1) is a composition for a gel polymer electrolyte is 3,000 g / mol to 5,000 g / mol.
  10. 청구항 1의 겔 폴리머 전해질용 조성물을 비활성 분위기하에서 전지에 주액 후, 중합시켜 형성된 것인 겔 폴리머 전해질.A gel polymer electrolyte formed by polymerizing the composition for gel polymer electrolyte of claim 1 in a cell under an inert atmosphere and then polymerizing.
  11. 음극, 양극, 상기 음극 및 양극 사이에 개재된 분리막, 및 A cathode interposed between the cathode, the anode, the cathode and the anode, and
    청구항 10의 겔 폴리머 전해질을 포함하는 것인 리튬 이차전지.Lithium secondary battery comprising a gel polymer electrolyte of claim 10.
PCT/KR2018/000647 2017-01-12 2018-01-12 Composition for gel polymer electrolyte and lithium secondary battery comprising same WO2018131953A1 (en)

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