WO2018139808A1 - Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery comprising same - Google Patents

Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery comprising same Download PDF

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Publication number
WO2018139808A1
WO2018139808A1 PCT/KR2018/000872 KR2018000872W WO2018139808A1 WO 2018139808 A1 WO2018139808 A1 WO 2018139808A1 KR 2018000872 W KR2018000872 W KR 2018000872W WO 2018139808 A1 WO2018139808 A1 WO 2018139808A1
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formula
secondary battery
aqueous electrolyte
lithium secondary
negative electrode
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PCT/KR2018/000872
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French (fr)
Korean (ko)
Inventor
유성훈
이경미
김슬기
이현영
강유선
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주식회사 엘지화학
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Priority claimed from KR1020180006124A external-priority patent/KR102112207B1/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to PL18745439T priority Critical patent/PL3404762T3/en
Priority to EP18745439.2A priority patent/EP3404762B1/en
Priority to CN201880001258.XA priority patent/CN108780923B/en
Priority to US16/078,290 priority patent/US20190341654A1/en
Publication of WO2018139808A1 publication Critical patent/WO2018139808A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
    • C07F7/02—Silicon compounds
    • C07F7/04—Esters of silicic acids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
    • C07F9/02—Phosphorus compounds
    • C07F9/06—Phosphorus compounds without P—C bonds
    • C07F9/08—Esters of oxyacids of phosphorus
    • C07F9/09—Esters of phosphoric acids
    • C07F9/098—Esters of polyphosphoric acids or anhydrides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
    • C07F9/02—Phosphorus compounds
    • C07F9/28—Phosphorus compounds with one or more P—C bonds
    • C07F9/535—Organo-phosphoranes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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 nonaqueous electrolyte for a lithium secondary battery having improved cycle life characteristics and high temperature storage characteristics, and a lithium secondary battery including the same.
  • Lithium batteries specifically lithium ion batteries (LIBs) are batteries that can best meet these needs, and have been adopted as power sources for many portable devices due to their high energy density and easy design.
  • LIBs lithium ion batteries
  • lithium ion batteries are adopted as power sources for electric vehicles or electric power storage in addition to small electronic devices such as portable IT devices, lithium ion batteries are capable of maintaining excellent performance not only at room temperature but also in more severe external environments such as high or low temperature environments. Research is expanding.
  • the lithium secondary battery currently applied is composed of a carbon material negative electrode capable of occluding and releasing lithium ions, a positive electrode made of lithium-containing transition metal oxide, and an electrolyte.
  • the non-aqueous solvent used in the electrolyte for the lithium secondary battery is various, but in terms of improving safety, a high boiling point solvent such as cyclic carbonate such as ethylene carbonate (EC), propylene carbonate (PC), or propylene ethylene carbonate (FEC) is used. It is desirable to.
  • a high boiling point solvent such as cyclic carbonate such as ethylene carbonate (EC), propylene carbonate (PC), or propylene ethylene carbonate (FEC) is used. It is desirable to.
  • One of the causes of the electrolyte side reaction is a small amount of water in the electrolyte generated in the battery manufacturing process.
  • the remaining water reacts with LiPF 6 , a lithium salt, to form HF, a strong acid, which decomposes during charging and discharging to release hydrogen gas, or deteriorates the surface of the anode to elute metal ions.
  • precipitation of Li metal is intensified while charging and discharging are repeated.
  • the first technical problem of the present invention is to provide a non-aqueous electrolyte solution for a lithium secondary battery comprising a compound serving as an HF scavenger as an additive.
  • the second technical problem of the present invention is to provide a lithium secondary battery having improved cycle life characteristics and high temperature storage performance by including the nonaqueous electrolyte solution for lithium secondary batteries.
  • non-aqueous electrolyte solution for a lithium secondary battery comprising at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a first additive.
  • R 1 to R 4 are each independently an alkyl group having 1 to 4 carbon atoms unsubstituted or substituted with a fluorine element.
  • R F 1 to R F 6 are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element,
  • R F 1 to R F 6 are not a fluorine element at the same time.
  • the fluoroethylene carbonate may be included in an amount of 0.1 wt% to 40 wt%, specifically 0.1 wt% to 30 wt%, and more specifically 5 wt% to 20 wt%, based on the total weight of the nonaqueous electrolyte. Can be.
  • the compound represented by Formula 1 may be at least one or more selected from the group consisting of compounds represented by Formulas 1a to 1e.
  • R F 1 and R F 2 are each independently an alkyl group having 1 to 3 carbon atoms substituted or unsubstituted with a fluorine element
  • R F 3 Is an alkyl group having 1 to 3 carbon atoms substituted with a fluorine element or a fluorine element
  • R F 4 , R F 5 and R F 6 may each independently be a fluorine element.
  • the compound represented by Chemical Formula 2 in the non-aqueous electrolyte of the present invention may be a compound represented by the following Chemical Formula 2a or Chemical Formula 2b.
  • the first additive may be included in an amount of 0.1 wt% to 10 wt%, specifically 1 wt% to 10 wt%, and more specifically 1 wt% to 7 wt%, based on the total weight of the nonaqueous electrolyte.
  • Positive electrode comprising a positive electrode active material
  • a separator interposed between the positive electrode and the negative electrode, and
  • It provides a lithium secondary battery comprising the nonaqueous electrolyte of the present invention.
  • the negative electrode active material may further include a carbon-based negative electrode active material.
  • a non-aqueous electrolyte for lithium secondary batteries including a compound serving as an HF scavenger as an additive may be provided, and a lithium secondary battery having improved cycle life characteristics and high temperature storage characteristics may be manufactured using the same.
  • non-aqueous electrolyte solution for a lithium secondary battery comprising at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a first additive.
  • R 1 to R 4 are each independently an alkyl group having 1 to 4 carbon atoms unsubstituted or substituted with a fluorine element.
  • R F 1 to R F 6 are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element,
  • R F 1 to R F 6 are not a fluorine element at the same time.
  • non-carbon negative electrode active materials such as silicon (Si) negative electrode active materials
  • SiO is mainly used among various silicon (Si) negative electrode active materials.
  • the SiO has the advantage of reducing the volume expansion of Si is generated Li 2 O as Li is inserted during the initial charging (reduction) process.
  • lithium salts such as LiPF 6
  • LiPF 6 which are electrolyte salts during secondary battery charge and discharge
  • HF gas that breaks down is generated, smooth operation of the SiO anode active material is inhibited.
  • the fluoroethylene carbonate compound is known to form a LiF-based strong and thin solid electrolyte interface (SEI) film on the surface of the silicon-based negative electrode, thereby increasing the amount of reversible Li ions and inhibiting the reaction between the electrolyte and the negative electrode.
  • SEI solid electrolyte interface
  • the solubility of the lithium salt is increased to improve the ionic conductivity of the nonaqueous electrolyte, By forming a relatively thin film on the surface of the cathode, output characteristics can be improved.
  • the fluoroethylene carbonate is 0.1 wt% to 40 wt%, specifically 0.1 wt% to 30 wt%, more specifically 5 wt% to 20 wt%, based on the total weight of the nonaqueous electrolyte. It may be included as.
  • the fluoroethylene carbonate When the fluoroethylene carbonate is included in the above range, it can bring a stable SEI film forming effect on the silicon-based negative electrode surface.
  • the fluoroethylene carbonate content exceeds 40% by weight, the viscosity of the non-aqueous electrolyte is increased, so that the wettability is lowered, and gas generation may occur during high temperature storage.
  • the fluoroethylene carbonate may generate a large amount of HF at a high temperature, there is a problem that the problem occurring in the secondary battery using the negative electrode including the silicon (Si) -based negative electrode active material cannot be completely improved.
  • the non-aqueous electrolyte contains at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a HF remover as a first additive together with fluoroethylene carbonate, the fluoro It was confirmed that HF generated during ethylene carbonate decomposition can be removed.
  • the compounds represented by Formula 1 and Formula 2 may consume at least two or more HFs per at least one molecule, thereby significantly improving hydrogen gas release or anode surface degradation caused by HF.
  • the compound of Formula 1 may include at least one selected from the group consisting of compounds represented by the following Formulas 1a to 1e.
  • R F 1 and R F 2 are each independently an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element
  • R F 3 is An fluorine element or an alkyl group having 1 to 3 carbon atoms substituted with a fluorine element
  • R F 4 , R F 5 and R F 6 may each independently be a fluorine element.
  • Examples of the compound of Formula 2 include a compound represented by the following Formula 2a or 2b.
  • the first additive may be included in an amount of 0.1 wt% to 10 wt%, specifically 1 to 10 wt%, and more specifically 1 wt% to 7 wt%, based on the total weight of the electrolyte.
  • the HF remover effect is insignificant.
  • the HF remover may act as a resistance increase factor by itself, and the reaction by-product with water may act as a resistance increase factor, when the content exceeds 10% by weight, the resistance is increased by an excessive amount of additives, and thus the secondary battery May decrease the electrochemical performance of the.
  • the water present in the secondary battery reacts with the electrolyte to form acid products (HF, POF 3 ), and these acid products, such as HF, are persistent side reactions such as dissolving the cathode active material and releasing hydrogen gas. It is known as a factor causing.
  • acid products such as HF
  • various Si-O bonds are present in the negative electrode containing Si. When these bonds are broken by HF, the performance of the battery is inevitably deteriorated.
  • this problem can be solved by providing a non-aqueous electrolyte containing an HF remover such as the compounds represented by Formulas 1 and 2 capable of scavengering HF or water (H 2 O).
  • an HF remover such as the compounds represented by Formulas 1 and 2 capable of scavengering HF or water (H 2 O).
  • the compound of Formula 1 included in the nonaqueous electrolyte of the present invention includes functional groups capable of removing HF, such as Si—O groups and isocyanate groups, in the structure. Therefore, while the Si-O bond of the compound represented by Formula 1 is broken during the high temperature storage process, it can be easily combined with HF or water (H 2 O) generated in the non-aqueous electrolyte to remove it.
  • functional groups capable of removing HF such as Si—O groups and isocyanate groups
  • the anion acts as a HF remover, so that F ⁇ replaces the fluorinated alkyl group of the anion to form a new PF bond, thereby removing HF or water and at the same time obtaining the effect of increasing Li ions.
  • the anion acts as a HF remover, so that F ⁇ replaces the fluorinated alkyl group of the anion to form a new PF bond, thereby removing HF or water and at the same time obtaining the effect of increasing Li ions. Can be.
  • the compounds can suppress the generation of LiF on the negative electrode SEI film during the initial charging to improve the output characteristics of the lithium secondary battery.
  • nonaqueous electrolyte of the present invention may further include at least one or more second additives selected from the group consisting of compounds represented by the following Chemical Formulas 3 and 4 as necessary.
  • R 5 to R 7 are each independently an alkyl group having 1 to 4 carbon atoms
  • n is an integer of any one of 1-10.
  • the compound represented by Formula 4 may be a compound represented by Formula 4a.
  • n is an integer of any one of 1-3.
  • the second additive may be included in an amount of 0.1 wt% to 10 wt%, specifically 1 wt% to 7 wt%, based on the total weight of the nonaqueous electrolyte.
  • the content of the second additive is less than 0.1% by weight, the effect of improving the HF remover is insignificant, and when the content of the second additive is more than 10% by weight, the resistance may be increased by the excess additive.
  • the compound represented by Formula 3 includes an isocyanate group as a functional group capable of removing HF in the structure, and the compound represented by Formula 4 includes Si-O groups as a functional group capable of removing HF in the structure. Therefore, the isocyanate bond of the compound represented by the formula (3) or the Si-O bond of the compound represented by the formula (4) is broken during the high temperature storage process, and easily formed with HF or water (H 2 O) generated in the nonaqueous electrolyte Can be combined to remove HF or water.
  • the isocyanate compound represented by Formula 3 when using the isocyanate compound represented by Formula 3 alone, it may react with a small amount of water in the battery or electrolyte to generate CO 2 causing primary amine and battery swelling. It can react with LiPF 6 to intensify HF gas generation.
  • the compound represented by the formula (4) alone when the compound represented by the formula (4) alone is used, phosphoric acid is generated during decomposition may lower the cell performance, or increase the electrolyte viscosity.
  • the compound represented by the formula (3) or 4 is more preferably used in combination with the compound of the formula (1) or (2) than used independently of each other.
  • the compounds may suppress the generation of LiF on the negative electrode SEI film during initial charging, thereby improving output characteristics of the lithium secondary battery.
  • the non-aqueous electrolyte of the present invention it is possible to implement the effect of improving the cycle life characteristics and high temperature storage characteristics of the secondary battery.
  • those lithium salts that are commonly used in lithium secondary battery electrolyte can be used without limitation, for example, Li + as a cation of the lithium salt, and as an anion 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 SO 3 -, C 4 F 9 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 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 -,
  • 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 a range generally available, but may be included in an electrolyte solution at a concentration of 0.8 M to 1.5 M in order to obtain an effect of forming an anti-corrosion film on the electrode surface.
  • the carbonate compound included in the organic solvent may include both a cyclic carbonate compound and a linear carbonate compound.
  • cyclic carbonate compound examples include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and 2,3-pentylene Carbonate, and vinylene carbonate, any one selected from the group consisting of, or a mixture of two or more thereof.
  • a high viscosity organic solvent may include ethylene carbonate that dissociates lithium salts in the electrolyte with high dielectric constant. have.
  • linear carbonate compound having low viscosity and low dielectric constant examples include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), and methylpropyl carbonate.
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethylmethyl carbonate
  • methylpropyl carbonate any one selected from the group consisting of ethylpropyl carbonate or a mixture of two or more thereof may be representatively used, but is not limited thereto.
  • the organic solvent may be used by adding an organic solvent commonly used in the electrolyte for lithium secondary batteries, without limitation, in order to prepare an electrolyte having a high electrical conductivity.
  • it may further include a mixture of at least two or more selected from the group consisting of ether compounds, and ester compounds.
  • the ether compound may be any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether and ethyl propyl ether, or a mixture of two or more thereof, but is not limited thereto. It is not.
  • the ester compound is any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, and gamma-butyrolactone Mixtures of two or more of them may be used, but are not limited thereto.
  • Positive electrode comprising a positive electrode active material
  • a separator interposed between the positive electrode and the negative electrode, and
  • the "silicon-based negative electrode active material” means a negative electrode active material containing a silicon-based compound.
  • the silicon-based compound is a material capable of doping and undoping lithium, and is a compound containing at least about 50 wt% or more, specifically about 70 wt% or more of silicon (Si) elements in the silicon-based compound.
  • the element Z is Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof Can be.
  • silicon-based negative active materials such as Si, SiO x , Si-Z alloys may include substantially crystalline (including single crystals, polycrystals), amorphous, or a mixture thereof.
  • the silicon-based compound may have a nanostructure having an average particle diameter (D50) of less than about 500 nm, for example, less than about 200 nm, less than about 100 nm, less than about 50 nm, or less than about 20 nm.
  • D50 average particle diameter
  • nanostructures may include nanoparticles, nanopowders, nanowires, nanorods, nanofibers, nanocrystals, nanodots, nanoribbons, and the like.
  • Such silicon-based negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode may further include a carbon-based negative electrode active material as needed with the silicon-based compound.
  • the carbon-based negative electrode active material is natural graphite, artificial graphite, graphite (graphite), graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), Carbon black, and a single material selected from the group consisting of graphite oxides or mixtures of two or more thereof, and specifically, may include artificial graphite or natural graphite.
  • the average particle diameter of the carbon-based negative electrode active material is not particularly limited, but if it is too small, the reactivity with the electrolyte may be high and the cycle characteristics may be lowered. If the carbon particle is too large, dispersion stability may be lowered when the negative electrode slurry is formed, and the surface of the negative electrode may be reduced. Can be rough.
  • the average particle diameter (D50) of the carbon-based negative electrode active material may be 5 to 30 ⁇ m, specifically 10 to 20 ⁇ m.
  • the carbon-based negative electrode active material may be a spherical shape having at least a part of a curved or curved shape, or may be a polygonal shape such as an approximate spherical shape or an elliptical shape even if not completely spherical, and may have irregularities on the surface.
  • the silicon compound and the carbon-based negative electrode active material when the silicon compound and the carbon-based negative electrode active material are mixed together in the negative electrode, the silicon compound: the carbon-based negative electrode active material may be included in a weight ratio of 2:98 to 100: 0.
  • the negative electrode may further include a binder and a conductive material in addition to the negative electrode active material.
  • the negative electrode may be prepared by coating a negative electrode active material 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 active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material slurry.
  • 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 binder may be included in an amount of 1 to 30% by weight based on the total weight of the negative electrode active material slurry as a component to assist in bonding between the conductive material, the active material and the current collector.
  • binders examples include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, and the like.
  • CMC carboxymethyl cellulose
  • EPDM ethylene-propylene-diene polymer
  • EPDM ethylene-propylene-diene polymer
  • sulfonated-EPDM styrene-butadiene rubber
  • fluorine rubber various copolymers thereof, and the like.
  • the conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 1 to 20 wt% based on the total weight of the negative electrode active material slurry.
  • the conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery.
  • carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black may be used.
  • Carbon powder 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 and the like can be used.
  • the solvent is a component that can be removed during drying, and may include an organic solvent such as water or NMP (N-methyl-2-pyrrolidone), and a preferable viscosity when including the negative electrode active material, and optionally a binder and a conductive material. It can be used in an amount such that 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%.
  • the positive electrode may be prepared by coating a positive electrode slurry containing a positive electrode active material, a binder, a conductive material and a solvent on a positive electrode 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
  • LiCoO 2 , LiMnO 2 , LiNiO 2 , and lithium nickel manganese cobalt oxides may be improved in capacity and stability of the battery.
  • the lithium composite metal oxide may be Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 , in view of the remarkable improvement effect according to the type and content ratio of the member forming the lithium composite metal oxide.
  • the cathode active material may be included in an amount of 80 wt% to 99 wt%, specifically 90 wt% to 99 wt%, based on the total weight of solids in the cathode slurry.
  • the energy density may be lowered, thereby lowering the capacity.
  • the binder is a component that assists the bonding of the active material, the conductive material, and the like to the current collector, and is generally added in an amount of 1 to 30% by weight based on the total weight of solids in the positive electrode slurry.
  • 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.
  • 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 lithium secondary battery of the present invention may further include a separator.
  • the lithium secondary battery of the present invention may be prepared by injecting the nonaqueous electrolyte of the present invention into an electrode structure consisting of a cathode, a cathode, and a separator interposed between the cathode and the anode.
  • the positive electrode, and the separator constituting the electrode structure may be used all those conventionally used in the manufacture of a lithium secondary battery.
  • the separator is made of a conventional porous polymer film commonly used, for example, polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer
  • a conventional porous nonwoven fabric for example, a non-woven fabric made of high melting glass fibers, polyethylene terephthalate fibers, or the like may be used, but is not limited thereto.
  • 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.
  • N-methyl-2-pyrrolidone as a solvent in a ratio of 90: 5: 5 (wt%) of lithium cobalt composite oxide (LiCoO 2 ) as a positive electrode active material, carbon black as a conductive material and polyvinylidene fluoride as a binder (NMP) was added to prepare a positive electrode slurry (40% solids).
  • the positive electrode slurry was applied to a positive electrode current collector (Al thin film) having a thickness of 100 ⁇ m, dried, and roll pressed to prepare a positive electrode.
  • SiO x (0 ⁇ x ⁇ 1) and natural graphite (average particle diameter (D50) 10 ⁇ m) as the negative electrode active material, polyvinylidene fluoride as the binder, and carbon black as the conductive material were 10: 85: 2: 3 (wt %)
  • NMP NMP
  • the positive electrode and the negative electrode prepared by the above-described method were laminated together with a polyethylene porous film to prepare an electrode assembly. Then, the prepared nonaqueous electrolyte was poured into the battery case, and the lithium secondary battery was prepared by sealing.
  • a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except for including the compound of Formula 2a instead of the compound of Formula 1a.
  • a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except for including the compound of Formula 2b instead of the compound of Formula 1a.
  • an electrolyte solution and a battery including the same were prepared in the same manner as in Example 1, except that 0.5 g of the compound of Formula 1a and 0.5 g of the compound of Formula 2a were included instead of the compound of Formula 1a. .
  • the non-aqueous electrolyte In preparing the non-aqueous electrolyte, the non-aqueous electrolyte and the same as in Example 1, except that 80g of the non-aqueous organic solvent includes 10g of fluoroethylene carbonate (FEC) and 10g of the compound represented by Formula 1a.
  • FEC fluoroethylene carbonate
  • Formula 1a To prepare a lithium secondary battery.
  • the non-aqueous electrolyte was prepared in the same manner as in Example 1, except that 98.8 g of the non-aqueous organic solvent contained 0.1 g of fluoroethylene carbonate (FEC) and 0.1 g of the compound represented by Formula 1a. And a lithium secondary battery comprising the same.
  • FEC fluoroethylene carbonate
  • a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except that neither fluoroethylene carbonate (FEC) nor the compound of Formula 1a were added.
  • FEC fluoroethylene carbonate
  • a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except that 95 g of the non-aqueous organic solvent contained 5 g of fluoroethylene carbonate (FEC).
  • FEC fluoroethylene carbonate
  • the batteries prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were subjected to constant current / constant voltage condition charging and 0.05C cut off charging to 0.15C at 4.35V, respectively, and discharged at 0.1C to 3.0V. Subsequently, constant current / constant voltage condition charging and 0.05C cut off charging were performed up to 4.35V at 0.8C rate, and discharged at 0.5C and 3.0V (initial discharge capacity).
  • the non-aqueous electrolyte containing the compound represented by Formula 1 or 2 alone It can be seen that the cycle life characteristics are more improved than the secondary batteries of Examples 1 to 3 and 5 provided.
  • the batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to constant current / constant voltage condition charging and 0.05C cut off charging to 0.15C at 4.35V, respectively, and discharged at 0.1C to 3.0V. Subsequently, constant current / constant voltage condition charging and 0.05C cut off charging were performed up to 4.35V at 0.8C rate, and discharged at 0.5C and 3.0V (initial discharge capacity).
  • the charge was again measured at constant current / constant voltage conditions up to 4.35 V at 0.8 C rate, 0.05 C cut off charging, and discharge at 0.5 C 3.0 V (recovery discharge amount).
  • the measured recovery discharge capacity is shown in Table 1 as% relative to the initial discharge amount.
  • the non-aqueous electrolyte containing the compound represented by Formula 1 or 2 alone It can be seen that both the residual discharge amount and the recovery discharge amount are superior to the secondary batteries of Examples 1 to 3 and 5 provided.

Abstract

The present invention relates to a non-aqueous electrolyte for a lithium secondary battery, the non-aqueous electrolyte comprising a compound acting as an HF scavenger, and to a lithium secondary battery, which has improved cycle life characteristics and high-temperature storage characteristics by comprising the non-aqueous electrolyte.

Description

리튬 이차전지용 비수전해액 및 이를 포함하는 리튬 이차전지Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery comprising same
관련 출원(들)과의 상호 인용Cross Citation with Related Application (s)
본 출원은 2017년 01월 26일자 한국 특허 출원 제2017-0012711호 및 2018년 01월 17일자 한국 특허 출원 제2018-0006124호에 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. 2017-0012711 dated January 26, 2017 and Korean Patent Application No. 2018-0006124 dated January 17, 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 사이클 수명 특성 및 고온 저장 특성이 향상된 리튬 이차전지용 비수전해액 및 이를 포함하는 리튬 이차전지에 관한 것이다.The present invention relates to a nonaqueous electrolyte for a lithium secondary battery having improved cycle life characteristics and high temperature storage characteristics, and a lithium secondary battery including the same.
최근 정보 통신 산업의 발전에 따라 전자 기기가 소형화, 경량화, 박형화 및 휴대화됨에 따라, 이러한 전자 기기의 전원으로 사용되는 전지의 고에너지 밀도화에 대한 요구가 높아지고 있다. 리튬 전지, 구체적으로 리튬 이온 전지(lithium ion battery: LIB)는 이러한 요구를 가장 잘 충족시킬 수 있는 전지로서, 에너지 밀도가 높고 설계가 용이하여 많은 휴대용 기기의 전원으로 채택되어 왔다. In recent years, as the electronic devices become smaller, lighter, thinner, and portable with the development of the information and communication industry, the demand for high energy density of batteries used as power sources for such electronic devices is increasing. Lithium batteries, specifically lithium ion batteries (LIBs), are batteries that can best meet these needs, and have been adopted as power sources for many portable devices due to their high energy density and easy design.
최근, 리튬 이온 전지가 휴대용 IT 기기 등의 소형 전자 기기 외에 전기 자동차용 또는 전력 저장용의 전원으로 채택되면서 상온에서뿐만 아니라 고온이나 저온 환경 등 보다 가혹한 외부 환경에서도 우수한 성능을 유지할 수 있는 리튬 이차전지에 대한 연구가 확대되고 있다. Recently, as lithium ion batteries are adopted as power sources for electric vehicles or electric power storage in addition to small electronic devices such as portable IT devices, lithium ion batteries are capable of maintaining excellent performance not only at room temperature but also in more severe external environments such as high or low temperature environments. Research is expanding.
현재 적용되고 있는 리튬 이차전지는 리튬이온을 흡장 및 방출할 수 있는 탄소재 음극과, 리튬 함유 전이금속 산화물 등으로 이루어진 양극 및 전해질로 구성되어 있다.The lithium secondary battery currently applied is composed of a carbon material negative electrode capable of occluding and releasing lithium ions, a positive electrode made of lithium-containing transition metal oxide, and an electrolyte.
상기 리튬 이차전지용 전해질에 사용되는 비수용매는 그 종류가 다양하지만, 안전성 향상 측면에서 고비점 용매, 예컨대 에틸렌 카보네이트(EC), 프로필렌 카보네이트(PC), 또는 프로필렌에틸렌카보네이트(FEC) 등의 환형 카보네이트를 사용하는 것이 바람직하다.The non-aqueous solvent used in the electrolyte for the lithium secondary battery is various, but in terms of improving safety, a high boiling point solvent such as cyclic carbonate such as ethylene carbonate (EC), propylene carbonate (PC), or propylene ethylene carbonate (FEC) is used. It is desirable to.
한편, 상기 리튬 이차전지를 고전압에서 사용할 경우 다음과 같은 문제가 발생할 수 있다.On the other hand, when using the lithium secondary battery at a high voltage may cause the following problems.
첫째, 고전압 범위에서의 충방전에 따른 음극활물질의 구조 변화에 기인하는 기계적 응력 반복에 의한 용량 열화와, 둘째 고전압 사용에　따른 전해액 부반응에 기인하는 금속 이온의 용출 및 부도체성 (Solid Electrolyte Interface; SEI)막 형성에 기인하는 용량 열화가 그것이다.First, dissolution and inductance of metal ions due to capacity deterioration due to mechanical stress repetition due to structural change of the negative electrode active material due to charge and discharge in the high voltage range, and second reaction of electrolyte due to high voltage use (Solid Electrolyte Interface; SEI) This is due to the capacity deterioration due to film formation.
상기 전해액 부반응을 야기하는 원인 중 하나는 전지 제조 공정에서 발생하는 전해액 내 소량의 수분이다. 이러한 잔존 수분은 리튬염인 LiPF6와 반응하여 강산인 HF를 형성시키고, 이러한 HF는 충방전 과정에서 분해되어 수소 가스를 방출하거나, 또는 양극 표면을 열화 시켜 금속 이온을 용출시키는 등 안전성에 문제를 야기할 수 있다. 상기 열화 현상은 충방전을 거듭하면서 Li 금속의 석출이 심화된다. One of the causes of the electrolyte side reaction is a small amount of water in the electrolyte generated in the battery manufacturing process. The remaining water reacts with LiPF 6 , a lithium salt, to form HF, a strong acid, which decomposes during charging and discharging to release hydrogen gas, or deteriorates the surface of the anode to elute metal ions. Can cause. In the deterioration phenomenon, precipitation of Li metal is intensified while charging and discharging are repeated.
이에, 제조 과정에서 가열 등을 통하여 수분을 제거하여 HF 발생을 저감시키는 방법이 제안되었으나, 활물질 등에 흡착되어 있는 수분을 완전히 제거하기란 매우 힘들다. Therefore, a method of reducing HF generation by removing moisture through heating in the manufacturing process has been proposed, but it is very difficult to completely remove the moisture adsorbed on the active material.
따라서, 전해액의 부반응에 의해 발생하는 HF를 제거하여, 용량 열화를 개선할 수 있는 이차전지의 개발이 요구되고 있다.Accordingly, there is a demand for development of a secondary battery capable of removing HF generated by side reaction of an electrolyte and improving capacity deterioration.
선행기술분야Prior art
한국 등록특허공보 1083882호Korean Patent Publication No. 1083882
본 발명의 제1 기술적 과제는 HF 제거제(scavenger) 역할을 하는 화합물을 첨가제로 포함하는 리튬 이차전지용 비수전해액을 제공하는 것이다.The first technical problem of the present invention is to provide a non-aqueous electrolyte solution for a lithium secondary battery comprising a compound serving as an HF scavenger as an additive.
또한, 본 발명의 제2 기술적 과제는 상기 리튬 이차전지용 비수전해액을 포함함으로써, 사이클 수명 특성 및 고온 저장 성능이 향상된 리튬 이차전지를 제공하는 것이다.In addition, the second technical problem of the present invention is to provide a lithium secondary battery having improved cycle life characteristics and high temperature storage performance by including the nonaqueous electrolyte solution for lithium secondary batteries.
상기의 목적을 달성하기 위한 본 발명의 일실시예에서는, In one embodiment of the present invention for achieving the above object,
리튬염, Lithium Salt,
제1 유기용매, First organic solvent,
플루오로에틸렌 카보네이트; 및Fluoroethylene carbonate; And
제1 첨가제로 하기 화학식 1 및 화학식 2로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상의 화합물;을 포함하는 리튬 이차전지용 비수전해액을 제공한다.It provides a non-aqueous electrolyte solution for a lithium secondary battery comprising at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a first additive.
[화학식 1][Formula 1]
Figure PCTKR2018000872-appb-I000001
Figure PCTKR2018000872-appb-I000001
상기 화학식 1에서,In Chemical Formula 1,
R1 내지 R4는 각각 독립적으로 불소 원소로 치환 또는 비치환된 탄소수 1 내지 4의 알킬기이다.R 1 to R 4 are each independently an alkyl group having 1 to 4 carbon atoms unsubstituted or substituted with a fluorine element.
[화학식 2][Formula 2]
Figure PCTKR2018000872-appb-I000002
Figure PCTKR2018000872-appb-I000002
상기 화학식 2에서,In Chemical Formula 2,
RF 1 내지 RF 6는 각각 독립적으로 불소 원소, 또는 불소 원소로 치환 또는 비치환된 탄소수 1 내지 3의 알킬기이고, R F 1 to R F 6 are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element,
이때 상기 RF 1 내지 RF 6가 동시에 불소 원소는 아니다.In this case, R F 1 to R F 6 are not a fluorine element at the same time.
본 발명의 비수전해액에서, 상기 플루오로에틸렌 카보네이트는 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 40 중량%, 구체적으로 0.1 중량% 내지 30 중량%, 보다 구체적으로 5 중량% 내지 20중량%로 포함될 수 있다. In the nonaqueous electrolyte of the present invention, the fluoroethylene carbonate may be included in an amount of 0.1 wt% to 40 wt%, specifically 0.1 wt% to 30 wt%, and more specifically 5 wt% to 20 wt%, based on the total weight of the nonaqueous electrolyte. Can be.
또한, 본 발명의 비수전해액에서, 상기 화학식 1로 표시되는 화합물은 하기 화학식 1a 내지 화학식 1e로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상일 수 있다.In addition, in the non-aqueous electrolyte of the present invention, the compound represented by Formula 1 may be at least one or more selected from the group consisting of compounds represented by Formulas 1a to 1e.
[화학식 1a][Formula 1a]
Figure PCTKR2018000872-appb-I000003
Figure PCTKR2018000872-appb-I000003
[화학식 1b][Formula 1b]
Figure PCTKR2018000872-appb-I000004
Figure PCTKR2018000872-appb-I000004
[화학식 1c][Formula 1c]
Figure PCTKR2018000872-appb-I000005
Figure PCTKR2018000872-appb-I000005
[화학식 1d][Formula 1d]
Figure PCTKR2018000872-appb-I000006
Figure PCTKR2018000872-appb-I000006
[화학식 1e][Formula 1e]
Figure PCTKR2018000872-appb-I000007
Figure PCTKR2018000872-appb-I000007
또한, 본 발명의 제1 첨가제 중 하나인 상기 화학식 2로 표시되는 화합물에서, RF 1 및 RF 2는 각각 독립적으로 불소 원소로 치환 또는 비치환된 탄소수 1 내지 3의 알킬기이고, RF 3는 불소 원소 또는 불소 원소로 치환된 탄소수 1 내지 3의 알킬기이며, RF 4, RF 5 및 RF 6은 각각 독립적으로 불소 원소일 수 있다. In addition, in the compound represented by Formula 2, which is one of the first additives of the present invention, R F 1 and R F 2 are each independently an alkyl group having 1 to 3 carbon atoms substituted or unsubstituted with a fluorine element, and R F 3 Is an alkyl group having 1 to 3 carbon atoms substituted with a fluorine element or a fluorine element, and R F 4 , R F 5 and R F 6 may each independently be a fluorine element.
구체적으로, 본 발명의 비수전해액에서 상기 화학식 2로 표시되는 화합물은 하기 화학식 2a 또는 화학식 2b로 표시되는 화합물일 수 있다.Specifically, the compound represented by Chemical Formula 2 in the non-aqueous electrolyte of the present invention may be a compound represented by the following Chemical Formula 2a or Chemical Formula 2b.
[화학식 2a][Formula 2a]
Figure PCTKR2018000872-appb-I000008
Figure PCTKR2018000872-appb-I000008
[화학식 2b][Formula 2b]
Figure PCTKR2018000872-appb-I000009
Figure PCTKR2018000872-appb-I000009
상기 제1 첨가제는 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 10 중량%, 구체적으로 1 중량% 내지 10 중량%, 보다 구체적으로 1 중량% 내지 7 중량%로 포함될 수 있다. The first additive may be included in an amount of 0.1 wt% to 10 wt%, specifically 1 wt% to 10 wt%, and more specifically 1 wt% to 7 wt%, based on the total weight of the nonaqueous electrolyte.
또한, 본 발명의 실시예에서는 In addition, in the embodiment of the present invention
양극활물질을 포함하는 양극, Positive electrode comprising a positive electrode active material,
실리콘계 음극활물질을 포함하는 음극,A negative electrode containing a silicon-based negative electrode active material,
상기 양극과 음극 사이에 개재된 분리막, 및A separator interposed between the positive electrode and the negative electrode, and
본 발명의 비수전해액을 포함하는 리튬 이차전지를 제공한다.It provides a lithium secondary battery comprising the nonaqueous electrolyte of the present invention.
이때, 상기 음극활물질은 탄소계 음극활물질을 추가로 포함할 수 있다.In this case, the negative electrode active material may further include a carbon-based negative electrode active material.
본 발명에서는 HF 제거제(scavenger) 역할을 하는 화합물을 첨가제로 포함하는 리튬 이차전지용 비수전해액을 제공하고, 이를 이용하여 사이클 수명 특성 및 고온 저장 특성이 향상된 리튬 이차전지를 제조할 수 있다.In the present invention, a non-aqueous electrolyte for lithium secondary batteries including a compound serving as an HF scavenger as an additive may be provided, and a lithium secondary battery having improved cycle life characteristics and high temperature storage characteristics may be manufactured using the same.
본 명세서에 첨부되는 다음의 도면은 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 아니다.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, the present invention is limited to the matters described in such drawings. It is not to be construed as limited.
도 1은 본 발명의 실험예 1에 따른 사이클 수명 특성 실험 결과를 나타낸 그래프이다.1 is a graph showing the cycle life characteristics test results 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.
구체적으로, 본 발명의 일 실시예에서는Specifically, in one embodiment of the present invention
리튬염, Lithium Salt,
제1 유기용매, First organic solvent,
플루오로에틸렌 카보네이트; 및Fluoroethylene carbonate; And
제1 첨가제로 하기 화학식 1 및 화학식 2로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상의 화합물;을 포함하는 리튬 이차전지용 비수전해액을 제공한다.It provides a non-aqueous electrolyte solution for a lithium secondary battery comprising at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a first additive.
[화학식 1][Formula 1]
Figure PCTKR2018000872-appb-I000010
Figure PCTKR2018000872-appb-I000010
상기 화학식 1에서,In Chemical Formula 1,
R1 내지 R4는 각각 독립적으로 불소 원소로 치환 또는 비치환된 탄소수 1 내지 4의 알킬기이다.R 1 to R 4 are each independently an alkyl group having 1 to 4 carbon atoms unsubstituted or substituted with a fluorine element.
[화학식 2][Formula 2]
Figure PCTKR2018000872-appb-I000011
Figure PCTKR2018000872-appb-I000011
상기 화학식 2에서,In Chemical Formula 2,
RF 1 내지 RF 6는 각각 독립적으로 불소 원소, 또는 불소 원소로 치환 또는 비치환된 탄소수 1 내지 3의 알킬기이고, R F 1 to R F 6 are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element,
이때 상기 RF 1 내지 RF 6가 동시에 불소 원소는 아니다.In this case, R F 1 to R F 6 are not a fluorine element at the same time.
일반적으로 전지 고용량화를 위해 비탄소계 음극활물질, 예컨대 실리콘(Si)계 음극활물질이 많이 사용되고 있으며, 여러 실리콘(Si)계 음극활물질 중에서도 SiO가 주로 사용되고 있다. 상기 SiO는 초기 충전(환원) 과정에서 Li이 삽입되면서 Li2O가 생성되어 Si 의 부피 팽창을 완화시켜주는 장점을 가지고 있다. Generally, non-carbon negative electrode active materials, such as silicon (Si) negative electrode active materials, are used to increase battery capacity, and SiO is mainly used among various silicon (Si) negative electrode active materials. The SiO has the advantage of reducing the volume expansion of Si is generated Li 2 O as Li is inserted during the initial charging (reduction) process.
하지만, 이차전지 충방전 시에 전해질염인 리튬염, 예컨대 LiPF6 등은 시간이 흐름에 따라 LiF 및 PF5 가스로 분해되고, 상기 발생된 PF5 가스가 다시 물 등과 반응하면서 Si-O 결합을 파괴하는 HF 가스를 발생시키기 때문에, SiO 음극활물질의 원활한 작동이 저해된다.However, lithium salts, such as LiPF 6 , which are electrolyte salts during secondary battery charge and discharge, decompose into LiF and PF 5 gases over time, and the generated PF 5 gas reacts with water to form Si-O bonds. Since HF gas that breaks down is generated, smooth operation of the SiO anode active material is inhibited.
더욱이, 상기 실리콘(Si)계 음극활물질과 불소를 함유하지 않는 일반적인 환형 카보네이트계 용매를 포함하는 전해액을 구비한 이차전지의 경우, 음극 표면에 부산물 발생이 심해지면서, 산소가 풍부한 (Oxygen rich) 두꺼운 막 등이 형성되면서, 용량감소가 지속되어 사이클 수명 특성 저하가 발생된다. Furthermore, in the case of a secondary battery having an electrolyte solution containing the silicon (Si) negative electrode active material and a general cyclic carbonate solvent that does not contain fluorine, the by-products are aggravated on the surface of the negative electrode. As the film or the like is formed, the capacity reduction is continued and a cycle life characteristic deterioration occurs.
상기 실리콘(Si)계 음극활물질을 포함하는 음극을 적용한 이차전지의 사이클 수명 개선 효과를 구현하기 위하여, 불소 함유 유기용매, 예컨대 플루오로에틸렌 카보네이트(FEC) 를 사용하는 방법이 제안되고 있다.In order to realize the cycle life improvement effect of the secondary battery using the negative electrode including the silicon (Si) -based negative electrode active material, a method using a fluorine-containing organic solvent such as fluoroethylene carbonate (FEC) has been proposed.
상기 플루오로에틸렌 카보네이트 화합물은 상기 실리콘계 음극 표면에 LiF 계열의 강력하고 얇은 SEI(solid electrolyte interface) 막을 형성하여, 가역 Li 이온의 양을 증가시키고 전해액과 음극의 사이의 반응을 억제할 수 있는 것으로 알려져 있다.The fluoroethylene carbonate compound is known to form a LiF-based strong and thin solid electrolyte interface (SEI) film on the surface of the silicon-based negative electrode, thereby increasing the amount of reversible Li ions and inhibiting the reaction between the electrolyte and the negative electrode. have.
상기 플루오로에틸렌 카보네이트를 비수전해액 내에 첨가제 또는 용매로 포함하는 경우, 불소를 함유하지 않는 일반적인 환형 카보네이트계 용매만으로 이루어진 비수전해액에 비하여, 리튬염의 용해도를 증가시켜 비수전해액의 이온전도도를 향상시키는 동시에, 음극 표면에 상대적으로 얇은 막을 형성하여, 출력 특성을 개선할 수 있다. When the fluoroethylene carbonate is included in the nonaqueous electrolyte as an additive or a solvent, compared to the nonaqueous electrolyte containing only a cyclic carbonate solvent containing no fluorine, the solubility of the lithium salt is increased to improve the ionic conductivity of the nonaqueous electrolyte, By forming a relatively thin film on the surface of the cathode, output characteristics can be improved.
본 발명의 비수전해액에 있어서, 상기 플루오로에틸렌 카보네이트는 상기 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 40 중량%, 구체적으로 0.1 중량% 내지 30 중량%, 보다 구체적으로 5 중량% 내지 20중량%로 포함될 수 있다.In the nonaqueous electrolyte of the present invention, the fluoroethylene carbonate is 0.1 wt% to 40 wt%, specifically 0.1 wt% to 30 wt%, more specifically 5 wt% to 20 wt%, based on the total weight of the nonaqueous electrolyte. It may be included as.
상기 플루오로에틸렌 카보네이트가 상기 범위로 포함될 때, 실리콘계 음극 표면에 안정한 SEI 막 형성 효과를 가져올 수 있다. 상기 플루오로에틸렌 카보네이트 함량이 40 중량%를 초과하는 경우, 비수전해액의 점도가 증가하여 젖음성이 낮아지고, 고온 저장 시 가스 발생이 야기될 수 있다.When the fluoroethylene carbonate is included in the above range, it can bring a stable SEI film forming effect on the silicon-based negative electrode surface. When the fluoroethylene carbonate content exceeds 40% by weight, the viscosity of the non-aqueous electrolyte is increased, so that the wettability is lowered, and gas generation may occur during high temperature storage.
하지만, 상기 플루오로에틸렌 카보네이트는 고온에서 다량의 HF를 발생할 수 있기 때문에, 상기 실리콘(Si)계 음극활물질을 포함하는 음극을 사용하는 이차전지에서 발생되는 문제점을 완전히 개선할 수 없다는 문제가 있다.However, since the fluoroethylene carbonate may generate a large amount of HF at a high temperature, there is a problem that the problem occurring in the secondary battery using the negative electrode including the silicon (Si) -based negative electrode active material cannot be completely improved.
이에, 본 발명에서는 상기 비수전해액에서 플루오로에틸렌 카보네이트와 함께 제1 첨가제로 HF 제거제인 하기 화학식 1 및 화학식 2로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상의 화합물을 포함하는 경우, 상기 플루오로에틸렌 카보네이트 분해 시에 발생되는 HF를 제거할 수 있음을 확인하였다. Thus, in the present invention, when the non-aqueous electrolyte contains at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a HF remover as a first additive together with fluoroethylene carbonate, the fluoro It was confirmed that HF generated during ethylene carbonate decomposition can be removed.
즉, 상기 화학식 1 및 화학식 2로 표시되는 화합물은 적어도 한 분자당 적어도 2개 이상의 HF를 소모할 수 있으므로, HF에 의해 야기되는 수소 가스 방출, 또는 양극 표면 열화를 현저히 개선할 수 있다. That is, the compounds represented by Formula 1 and Formula 2 may consume at least two or more HFs per at least one molecule, thereby significantly improving hydrogen gas release or anode surface degradation caused by HF.
본 발명의 비수전해액에 있어서, 상기 화학식 1의 화합물은 그 대표적인 예로 하기 화학식 1a 내지 화학식 1e로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상을 들 수 있다.In the non-aqueous electrolyte of the present invention, the compound of Formula 1 may include at least one selected from the group consisting of compounds represented by the following Formulas 1a to 1e.
[화학식 1a][Formula 1a]
Figure PCTKR2018000872-appb-I000012
Figure PCTKR2018000872-appb-I000012
[화학식 1b][Formula 1b]
Figure PCTKR2018000872-appb-I000013
Figure PCTKR2018000872-appb-I000013
[화학식 1c][Formula 1c]
Figure PCTKR2018000872-appb-I000014
Figure PCTKR2018000872-appb-I000014
[화학식 1d][Formula 1d]
Figure PCTKR2018000872-appb-I000015
Figure PCTKR2018000872-appb-I000015
[화학식 1e][Formula 1e]
Figure PCTKR2018000872-appb-I000016
Figure PCTKR2018000872-appb-I000016
또한, 본 발명의 비수전해액에 있어서, 상기 화학식 2로 표시되는 화합물에서, RF 1 및 RF 2는 각각 독립적으로 불소 원소로 치환 또는 비치환된 탄소수 1 내지 3의 알킬기이고, RF 3는 불소 원소 또는 불소 원소로 치환된 탄소수 1 내지 3의 알킬기이며, RF 4, RF 5 및 RF 6은 각각 독립적으로 불소 원소일 수 있다.In the non-aqueous electrolyte of the present invention, in the compound represented by Formula 2, R F 1 and R F 2 are each independently an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element, and R F 3 is An fluorine element or an alkyl group having 1 to 3 carbon atoms substituted with a fluorine element, and R F 4 , R F 5 and R F 6 may each independently be a fluorine element.
상기 화학식 2의 화합물은 그 대표적인 예로 하기 화학식 2a 또는 화학식 2b로 표시되는 화합물을 들 수 있다.Examples of the compound of Formula 2 include a compound represented by the following Formula 2a or 2b.
[화학식 2a][Formula 2a]
Figure PCTKR2018000872-appb-I000017
Figure PCTKR2018000872-appb-I000017
[화학식 2b][Formula 2b]
Figure PCTKR2018000872-appb-I000018
Figure PCTKR2018000872-appb-I000018
상기 제1 첨가제는 전해액 전체 중량을 기준으로 0.1 중량% 내지 10 중량%, 구체적으로 1 내지 10 중량%, 보다 구체적으로 1 중량% 내지 7 중량%로 포함될 수 있다. The first additive may be included in an amount of 0.1 wt% to 10 wt%, specifically 1 to 10 wt%, and more specifically 1 wt% to 7 wt%, based on the total weight of the electrolyte.
상기 제1 첨가제의 함량이 0.1 중량% 미만이면 HF 제거제 효과가 미미하다. 또한, HF 제거제는 그 자체로서 저항 증가 요인으로 작용할 수 있고, 또한, 수분과의 반응 부산물이 저항 증가 요인으로 작용할 수 있으므로, 10 중량%를 초과하는 경우에는 과량의 첨가제 의해 저항이 증가되어 이차전지의 전기화학적 성능을 저하시킬 수 있다.If the content of the first additive is less than 0.1% by weight, the HF remover effect is insignificant. In addition, since the HF remover may act as a resistance increase factor by itself, and the reaction by-product with water may act as a resistance increase factor, when the content exceeds 10% by weight, the resistance is increased by an excessive amount of additives, and thus the secondary battery May decrease the electrochemical performance of the.
상술한 바와 같이, 이차전지 내에서 존재하는 수분은 전해액과 반응하여 산 생성물 (HF, POF3)을 형성하고, 이러한 산 생성물, 예컨대 HF는 양극활물질을 용해시키고, 수소 가스를 방출하는 등 지속적인 부반응을 일으키는 인자로 알려져 있다. 특히, Si가 포함된 음극에서는 다양한 Si-O 결합들이 존재하게 되는데, 이 결합들이 HF에 의해 파괴되면 전지의 성능은 심하게 저하될 수밖에 없다.As described above, the water present in the secondary battery reacts with the electrolyte to form acid products (HF, POF 3 ), and these acid products, such as HF, are persistent side reactions such as dissolving the cathode active material and releasing hydrogen gas. It is known as a factor causing. Particularly, various Si-O bonds are present in the negative electrode containing Si. When these bonds are broken by HF, the performance of the battery is inevitably deteriorated.
본 발명에서는 HF나 물(H2O)을 제거(scavenger)할 수 있는 상기 화학식 1 및 2로 표시되는 화합물과 같은 HF 제거제를 포함하는 비수전해액을 제공함으로써, 이러한 문제를 해결할 수 있다.In the present invention, this problem can be solved by providing a non-aqueous electrolyte containing an HF remover such as the compounds represented by Formulas 1 and 2 capable of scavengering HF or water (H 2 O).
즉, 본 발명의 비수전해액에 포함되는 상기 화학식 1의 화합물은 구조 내에 Si-O기 및 이소시아네이트기 등 HF를 제거할 수 있는 작용기를 각각 포함하고 있다. 따라서, 고온 저장 과정 중에 상기 화학식 1로 표시되는 화합물의 Si-O 결합이 끊어지면서, 비수전해액 내에 생성된 HF나 물(H2O)과 쉽게 결합하여 이를 제거할 수 있다. That is, the compound of Formula 1 included in the nonaqueous electrolyte of the present invention includes functional groups capable of removing HF, such as Si—O groups and isocyanate groups, in the structure. Therefore, while the Si-O bond of the compound represented by Formula 1 is broken during the high temperature storage process, it can be easily combined with HF or water (H 2 O) generated in the non-aqueous electrolyte to remove it.
또한, 상기 화학식 2로 표시되는 화합물의 경우 음이온이 HF 제거제 역할을 수행하여, F-가 음이온의 불소화 알킬기를 치환하여 새로운 P-F 결합을 형성하면서 HF 또는 물을 제거하는 동시에 Li 이온 증가의 효과도 얻을 수 있다.In addition, in the case of the compound represented by Formula 2, the anion acts as a HF remover, so that F − replaces the fluorinated alkyl group of the anion to form a new PF bond, thereby removing HF or water and at the same time obtaining the effect of increasing Li ions. Can be.
이와 같이, 본 발명에서는 HF 제거제를 첨가제로 포함하는 비수전해액을 제공함으로써, 상기 화합물들이 초기 충전 시 음극 SEI 막 상에 LiF의 생성을 억제하여 리튬 이차전지의 출력 특성을 향상시킬 수 있다.As such, in the present invention, by providing a non-aqueous electrolyte containing an HF remover as an additive, the compounds can suppress the generation of LiF on the negative electrode SEI film during the initial charging to improve the output characteristics of the lithium secondary battery.
한편, 본 발명의 비수전해액은 필요에 따라 하기 화학식 3 및 화학식 4로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상의 제2 첨가제를 더 포함할 수도 있다.Meanwhile, the nonaqueous electrolyte of the present invention may further include at least one or more second additives selected from the group consisting of compounds represented by the following Chemical Formulas 3 and 4 as necessary.
[화학식 3][Formula 3]
Figure PCTKR2018000872-appb-I000019
Figure PCTKR2018000872-appb-I000019
[화학식 4] [Formula 4]
Figure PCTKR2018000872-appb-I000020
Figure PCTKR2018000872-appb-I000020
상기 화학식 4에서,In Chemical Formula 4,
R5 내지 R7는 각각 독립적으로 탄소수 1 내지 4의 알킬기이고,R 5 to R 7 are each independently an alkyl group having 1 to 4 carbon atoms,
n은 1 내지 10 중 어느 하나의 정수이다.n is an integer of any one of 1-10.
이때, 상기 화학식 4로 표시되는 화합물은 하기 화학식 4a로 표시되는 화합물일 수 있다.In this case, the compound represented by Formula 4 may be a compound represented by Formula 4a.
[화학식 4a][Formula 4a]
Figure PCTKR2018000872-appb-I000021
Figure PCTKR2018000872-appb-I000021
상기 화학식에서,In the above formula,
n은 1 내지 3 중 어느 하나의 정수이다.n is an integer of any one of 1-3.
상기 제2 첨가제는 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 10 중량%, 구체적으로 1 중량% 내지 7 중량%로 포함될 수 있다. 상기 제2 첨가제의 함량이 0.1 중량% 미만이면 HF 제거제 개선 효과가 미미하며, 10 중량%를 초과하는 경우에는 과량의 첨가제에 의해 저항이 증가할 수 있다.The second additive may be included in an amount of 0.1 wt% to 10 wt%, specifically 1 wt% to 7 wt%, based on the total weight of the nonaqueous electrolyte. When the content of the second additive is less than 0.1% by weight, the effect of improving the HF remover is insignificant, and when the content of the second additive is more than 10% by weight, the resistance may be increased by the excess additive.
상기 화학식 3으로 표시되는 화합물은 구조 내에 HF를 제거할 수 있는 작용기로 이소시아네이트기를 포함하고, 화학식 4로 표시되는 화합물은 구조 내에 HF를 제거할 수 있는 작용기로 Si-O기를 각각 포함하고 있다. 따라서, 고온 저장 과정 중에 상기 화학식 3으로 표시되는 화합물의 이소시아네이트 결합이 변형되거나, 화학식 4로 표시되는 화합물의 Si-O 결합이 끊어지면서, 비수전해액 내에 생성되는 HF나 물(H2O)과 쉽게 결합하여 HF나 물을 제거할 수 있다. The compound represented by Formula 3 includes an isocyanate group as a functional group capable of removing HF in the structure, and the compound represented by Formula 4 includes Si-O groups as a functional group capable of removing HF in the structure. Therefore, the isocyanate bond of the compound represented by the formula (3) or the Si-O bond of the compound represented by the formula (4) is broken during the high temperature storage process, and easily formed with HF or water (H 2 O) generated in the nonaqueous electrolyte Can be combined to remove HF or water.
이때, 상기 화학식 3으로 표시되는 이소시아네이트계 화합물을 단독으로 사용하는 경우, 전지나 전해액 내의 소량의 수분과 반응하여 1차 아민과 전지 부풀음을 야기하는 CO2를 발생시킬 수 있으며, 상기 아민과 같은 물질은 LiPF6와 반응하여 HF 가스 발생을 심화할 수 있다. 또한, 상기 화학식 4로 표시되는 화합물을 단독으로 사용하는 경우, 분해 시에 인산이 생성되어 셀 성능을 저하시키거나, 전해액 점도를 상승시킬 수 있다. 이러한 단점을 방지하기 위하여, 상기 화학식 3 또는 4로 표시되는 화합물은 각각 독립적으로 사용하는 것보다, 상기 화학식 1 또는 2의 화합물과 혼합하여 사용하는 것이 보다 바람직하다. In this case, when using the isocyanate compound represented by Formula 3 alone, it may react with a small amount of water in the battery or electrolyte to generate CO 2 causing primary amine and battery swelling. It can react with LiPF 6 to intensify HF gas generation. In addition, when the compound represented by the formula (4) alone is used, phosphoric acid is generated during decomposition may lower the cell performance, or increase the electrolyte viscosity. In order to prevent these disadvantages, the compound represented by the formula (3) or 4 is more preferably used in combination with the compound of the formula (1) or (2) than used independently of each other.
이와 같이, 본 발명의 HF 제거제를 포함하는 비수전해액을 사용하는 경우, 상기 화합물들이 초기 충전 시 음극 SEI 막 상에 LiF의 생성을 억제하여 리튬 이차전지의 출력 특성을 향상시킬 수 있다. 특히, 본 발명의 비수전해액을 포함하는 경우, 이차전지의 사이틀 수명 특성 및 고온 저장 특성 향상 효과를 구현할 수 있다.As such, when the nonaqueous electrolyte containing the HF remover of the present invention is used, the compounds may suppress the generation of LiF on the negative electrode SEI film during initial charging, thereby improving output characteristics of the lithium secondary battery. In particular, when including the non-aqueous electrolyte of the present invention, it is possible to implement the effect of improving the cycle life characteristics and high temperature storage characteristics of the secondary battery.
한편, 본 발명의 리튬 이차전지용 비수전해액에 있어서, 상기 리튬염은 리튬 이차전지용 전해액에 통상적으로 사용되는 것들이 제한 없이 사용될 수 있으며, 예를 들어 상기 리튬염의 양이온으로 Li+를 포함하고, 음이온으로는 F-, Cl-, Br-, I-, NO3 -, N(CN)2 -, BF4 -, ClO4 -, AlO4 -, AlCl4 -, PF6 -, SbF6 -, AsF6 -, BF2C2O4 -, BC4O8 -, CF3SO3 -, C4F9SO3 -, CF3CF2SO3 -, (CF3SO2)2N-, (FSO2)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.On the other hand, in the non-aqueous electrolyte for lithium secondary batteries of the present invention, those lithium salts that are commonly used in lithium secondary battery electrolyte can be used without limitation, for example, Li + as a cation of the lithium salt, and as an anion 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 SO 3 -, C 4 F 9 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 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 - can include at least one selected from the group consisting of - and (CF 3 CF 2 SO 2) 2 N.
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 막 형성 효과를 얻기 위하여, 전해액 내에 0.8 M 내지 1.5M의 농도로 포함할 수 있다. 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 a range generally available, but may be included in an electrolyte solution at a concentration of 0.8 M to 1.5 M in order to obtain an effect of forming an anti-corrosion film on the electrode surface.
또한, 본 발명의 리튬 이차전지용 비수전해액에 있어서, 상기 유기용매에 포함되는 카보네이트 화합물은 환형 카보네이트 화합물 및 선형 카보네이트 화합물을 모두 포함할 수 있다. In addition, in the nonaqueous electrolyte solution for lithium secondary batteries of the present invention, the carbonate compound included in the organic solvent may include both a cyclic carbonate compound and a linear carbonate compound.
상기 환형 카보네이트 화합물은 그 구체적인 예로 에틸렌 카보네이트(EC), 프로필렌 카보네이트(PC), 1,2-부틸렌 카보네이트, 2,3-부틸렌 카보네이트, 1,2-펜틸렌카보네이트, 2,3-펜틸렌 카보네이트, 및 비닐렌 카보네이트로 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 들 수 있으며, 이 중에서도 고점도의 유기용매로서 유전율이 높아 전해질 내의 리튬염을 잘 해리시키는 에틸렌 카보네이트를 포함할 수 있다.Specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and 2,3-pentylene Carbonate, and vinylene carbonate, any one selected from the group consisting of, or a mixture of two or more thereof. Among them, a high viscosity organic solvent may include ethylene carbonate that dissociates lithium salts in the electrolyte with high dielectric constant. have.
또한, 상기 저점도 및 저유전율을 가지는 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 having low viscosity and low dielectric constant include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), and methylpropyl carbonate. And any one selected from the group consisting of ethylpropyl carbonate or a mixture of two or more thereof may be representatively used, but is not limited thereto.
또한, 상기 유기 용매는 높은 전기 전도율을 갖는 전해액을 제조하기 위하여, 리튬 이차전지용 전해액에 통상적으로 사용되는 유기용매를 제한 없이 추가하여 사용할 수 있다. 예를 들면, 에테르 화합물, 및 에스테르 화합물로 이루어진 군으로부터 선택된 적어도 2 이상의 혼합물을 추가로 포함할 수 있다.In addition, the organic solvent may be used by adding an organic solvent commonly used in the electrolyte for lithium secondary batteries, without limitation, in order to prepare an electrolyte having a high electrical conductivity. For example, it may further include a mixture of at least two or more selected from the group consisting of ether compounds, and ester compounds.
상기 에테르 화합물로는 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.The ether compound may be any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether and ethyl propyl ether, or a mixture of two or more thereof, but is not limited thereto. It is not.
상기 에스테르 화합물로는 메틸 아세테이트, 에틸 아세테이트, 프로필 아세테이트, 메틸 프로피오네이트, 에틸 프로피오네이트, 프로필 프로피오네이트, 부틸 프로피오네이트, 및 감마-부티로락톤으로 이루어진 군으로부터 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 사용할 수 있으나, 이에 한정되는 것은 아니다.The ester compound is any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, and gamma-butyrolactone Mixtures of two or more of them may be used, but are not limited thereto.
또한, 본 발명의 일 실시예에서는In addition, in one embodiment of the present invention
양극활물질을 포함하는 양극, Positive electrode comprising a positive electrode active material,
실리콘계 음극활물질을 포함하는 음극,A negative electrode containing a silicon-based negative electrode active material,
상기 양극 및 음극 사이에 개재된 분리막, 및A separator interposed between the positive electrode and the negative electrode, and
본 발명의 전해액을 포함하는 리튬 이차전지를 제공한다.It provides a lithium secondary battery comprising the electrolyte solution of the present invention.
일 실시예에 따른 본 발명의 리튬 이차전지에 있어서, 상기 "실리콘계 음극활물질"이란, 실리콘계 화합물을 포함하는 음극활물질을 의미한다.In the lithium secondary battery of the present invention according to an embodiment, the "silicon-based negative electrode active material" means a negative electrode active material containing a silicon-based compound.
상기 실리콘계 화합물은 리튬을 도프 및 탈도프할 수 있는 물질로서, 실리콘계 화합물 내에 적어도 약 50 중량% 이상, 구체적으로 약 70 중량% 이상의 실리콘(Si) 원소를 포함하는 화합물로서, 그 대표적인 예로 Si, SiOx(0<x<2), Si-Z 합금(여기서, 상기 Z는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 또는 이들의 조합 원소이며, Si 은 아님) 및 이들의 조합에서 선택되는 물질을 포함할 수 있다. 상기 원소 Z는 Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택될 수 있다. 또한, 이와 같은 Si, SiOx, Si-Z 합금 등의 실리콘계 음극 활물질은 실질적으로 결정성(단결정, 다결정을 포함한다), 비결정성, 또는 이들의 혼합된 형태를 포함할 수 있다.The silicon-based compound is a material capable of doping and undoping lithium, and is a compound containing at least about 50 wt% or more, specifically about 70 wt% or more of silicon (Si) elements in the silicon-based compound. x (0 <x <2), Si-Z alloy, wherein Z is an alkali metal, alkaline earth metal, group 13 element, group 14 element, group 15 element, group 16 element, transition metal, rare earth element, or a combination thereof Element, not Si), and combinations thereof. The element Z is Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof Can be. In addition, such silicon-based negative active materials such as Si, SiO x , Si-Z alloys may include substantially crystalline (including single crystals, polycrystals), amorphous, or a mixture thereof.
상기 실리콘계 화합물은 평균입경(D50)이 약 500nm 미만, 예를 들면 약 200nm 미만, 약 100nm 미만, 약 50nm 미만, 또는 약 20nm 미만인 나노구조를 가질 수 있다. 이러한 나노구조의 예로는, 나노입자, 나노파우더, 나노와이어, 나노로드, 나노파이버, 나노크리스탈, 나노닷, 나노리본 등을 포함할 수 있다.The silicon-based compound may have a nanostructure having an average particle diameter (D50) of less than about 500 nm, for example, less than about 200 nm, less than about 100 nm, less than about 50 nm, or less than about 20 nm. Examples of such nanostructures may include nanoparticles, nanopowders, nanowires, nanorods, nanofibers, nanocrystals, nanodots, nanoribbons, and the like.
이러한 실리콘계 음극활물질은 1종을 단독으로 또는 2종 이상을 조합하여 사용할 수 있다.Such silicon-based negative electrode active materials may be used alone or in combination of two or more.
더욱이, 상기 음극은 실리콘계 화합물과 함께 필요에 따라 탄소계 음극활물질을 더 포함할 수 있다.Furthermore, the negative electrode may further include a carbon-based negative electrode active material as needed with the silicon-based compound.
상기 탄소계 음극활물질은 천연 흑연, 인조 흑연, 흑연(graphite), 이흑연화성 탄소(graphitizable carbon, 소프트 카본(softcarbon)), 난흑연화성 탄소(non-graphitizable carbon, 하드 카본(hard carbon)), 카본 블랙, 및 흑연 산화물로 이루어진 군으로부터 선택된 단일물 또는 이들 중 2종 이상의 혼합물을 들 수 있으며, 구체적으로, 인조흑연 또는 천연흑연을 포함할 수 있다.The carbon-based negative electrode active material is natural graphite, artificial graphite, graphite (graphite), graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), Carbon black, and a single material selected from the group consisting of graphite oxides or mixtures of two or more thereof, and specifically, may include artificial graphite or natural graphite.
상기 탄소계 음극활물질의 평균 입경은 특별히 한정되는 것은 아니나, 지나치게 작을 경우에는 전해액과의 반응성이 높아서 사이클 특성이 저하될 수 있으며, 지나치게 클 경우에는 음극 슬러리 형성시 분산안정성이 저하되고 음극의 표면이 거칠어질 수 있다. 이에, 상기 탄소계 음극활물질의 평균 입경(D50)은 5 내지 30 ㎛, 구체적으로 10 내지 20 ㎛ 일 수 있다.The average particle diameter of the carbon-based negative electrode active material is not particularly limited, but if it is too small, the reactivity with the electrolyte may be high and the cycle characteristics may be lowered. If the carbon particle is too large, dispersion stability may be lowered when the negative electrode slurry is formed, and the surface of the negative electrode may be reduced. Can be rough. Thus, the average particle diameter (D50) of the carbon-based negative electrode active material may be 5 to 30 ㎛, specifically 10 to 20 ㎛.
또한, 상기 탄소계 음극활물질은 적어도 일부가 만곡 또는 굴곡한 외형을 갖는 구상, 또는 완전한 구형상이 아니어도 대략적인 구형상 또는 타원형상 등 다각형상일 수 있고, 표면에 요철을 가질 수도 있다. In addition, the carbon-based negative electrode active material may be a spherical shape having at least a part of a curved or curved shape, or may be a polygonal shape such as an approximate spherical shape or an elliptical shape even if not completely spherical, and may have irregularities on the surface.
상기 본 발명의 이차전지에 있어서, 음극 내에 실리콘계 화합물과 탄소계 음극활물질이 함께 혼용된 경우, 상기 실리콘계 화합물 : 탄소계 음극활물질은 2:98 내지 100:0의 중량비로 포함될 수 있다.In the secondary battery of the present invention, when the silicon compound and the carbon-based negative electrode active material are mixed together in the negative electrode, the silicon compound: the carbon-based negative electrode active material may be included in a weight ratio of 2:98 to 100: 0.
또한, 상기 음극은 상기 음극활물질 외에 바인더 및 도전재 등을 추가로 포함할 수 있다. In addition, the negative electrode may further include a binder and a conductive material in addition to the negative electrode active material.
상기 음극은 음극 집전체 상에 음극 활물질, 바인더, 도전재 및 용매 등을 포함하는 음극 활물질 슬러리를 코팅한 후, 건조 및 압연하여 제조할 수 있다.The negative electrode may be prepared by coating a negative electrode active material 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 활물질은 음극 활물질 슬러리의 전체 중량을 기준으로 80 중량% 내지 99 중량%로 포함될 수 있다.The negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material slurry.
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.
상기 바인더는 도전재, 활물질 및 집전체 간의 결합에 조력하는 성분으로서, 음극 활물질 슬러리의 전체 중량을 기준으로 1 내지 30 중량%로 포함될 수 있다.　The binder may be included in an amount of 1 to 30% by weight based on the total weight of the negative electrode active material slurry as a component to assist in bonding between the conductive material, the active material and the current collector.
이러한 바인더의 예로는, 폴리비닐리덴플루오라이드, 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.Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, and the like.
상기 도전재는 음극 활물질의 도전성을 더욱 향상시키기 위한 성분으로서, 음극 활물질 슬러리의 전체 중량을 기준으로 1 내지 20 중량%로 첨가될 수 있다.　이러한 도전재는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 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 있다. The conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 1 to 20 wt% based on the total weight of the negative electrode active material slurry. The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black may be used. Carbon powder; 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 and the like can be used.
상기 용매는 건조 시 제거 가능한 성분으로, 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 is a component that can be removed during drying, and may include an organic solvent such as water or NMP (N-methyl-2-pyrrolidone), and a preferable viscosity when including the negative electrode active material, and optionally a binder and a conductive material. It can be used in an amount such that 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, 본 발명의 리튬 이차전지에 있어서, 상기 양극은 양극 집전체 상에 양극활물질, 바인더, 도전재 및 용매 등을 포함하는 양극 슬러리를 코팅한 다음, 건조 및 압연하여 제조할 수 있다.In addition, in the lithium secondary battery of the present invention, the positive electrode may be prepared by coating a positive electrode slurry containing a positive electrode active material, a binder, a conductive material and a solvent on a positive electrode 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 독립적인 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. 이중에서도 전지의 용량 특성 및 안정성을 높일 수 있다는 점에서 상기 리튬 복합금속 산화물은 LiCoO2, LiMnO2, LiNiO2, 리튬 니켈망간코발트 산화물(예를 들면, Li(Ni0.6Mn0.2Co0.2)O2, Li(Ni0.5Mn0.3Co0.2)O2, 또는 Li(Ni0.8Mn0.1Co0.1)O2 등), 또는 리튬 니켈코발트알루미늄 산화물(예를 들면, Li(Ni0.8Co0.15Al0.05)O2 등) 등일 수 있으며, 리튬 복합금속 산화물을 형성하는 구성원소의 종류 및 함량비 제어에 따른 개선 효과의 현저함을 고려할 때 상기 리튬 복합금속 산화물은 Li(Ni0.6Mn0.2Co0.2)O2, Li(Ni0.5Mn0.3Co0.2)O2, Li(Ni0.7Mn0.15Co0.15)O2 또는 Li(Ni0.8Mn0.1Co0.1)O2 등일 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 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 the independent 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. Among the lithium composite metal oxides, LiCoO 2 , LiMnO 2 , LiNiO 2 , and lithium nickel manganese cobalt oxides (eg, Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 may be improved in capacity and stability of the battery. , Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , or Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 , or the like, or lithium nickel cobalt aluminum oxide (for example, Li (Ni 0.8 Co 0.15 Al 0.05 ) O 2, etc. ), And the lithium composite metal oxide may be Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 , in view of the remarkable improvement effect according to the type and content ratio of the member forming the lithium composite metal oxide. Li (Ni 0.5 Mn 0.3 Co 0.2 ) O 2 , Li (Ni 0.7 Mn 0.15 Co 0.15 ) O 2, or Li (Ni 0.8 Mn 0.1 Co 0.1 ) O 2 , and the like, and any one or a mixture of two or more thereof may be used. have.
상기 양극 활물질은 양극 슬러리 중 고형분의 전체 중량을 기준으로 80 중량% 내지 99 중량%, 구체적으로 90 중량% 내지 99 중량%로 포함될 수 있다.The cathode active material may be included in an amount of 80 wt% to 99 wt%, specifically 90 wt% to 99 wt%, based on the total weight of solids in the cathode slurry.
이때, 상기 양극 활물질의 함량이 80 중량% 이하인 경우 에너지 밀도가 낮아져 용량이 저하될 수 있다.In this case, when the content of the positive electrode active material is 80% by weight or less, the energy density may be lowered, thereby lowering the capacity.
또한, 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. 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.In addition, the binder is a component that assists the bonding of the active material, the conductive material, and the like to the current collector, and is generally added in an amount of 1 to 30% by weight based on the total weight of solids in the positive electrode slurry. 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.
또한, 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.In addition, 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%.
상기 본 발명의 리튬 이차전지는 분리막을 추가로 포함할 수 있다.The lithium secondary battery of the present invention may further include a separator.
구체적으로, 본 발명의 리튬 이차전지는 양극, 음극 및 양극과 음극 사이에 개재된 분리막으로 이루어진 전극 구조체에 본 발명의 비수 전해액을 주입하여 제조할 수 있다. 이때, 전극 구조체를 이루는 양극, 및 분리막은 리튬 이차전지 제조에 통상적으로 사용되던 것들이 모두 사용될 수 있다.Specifically, the lithium secondary battery of the present invention may be prepared by injecting the nonaqueous electrolyte of the present invention into an electrode structure consisting of a cathode, a cathode, and a separator interposed between the cathode and the anode. At this time, the positive electrode, and the separator constituting the electrode structure may be used all those conventionally used in the manufacture of a lithium secondary battery.
상기 분리막은 일반적으로 사용되는 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.The separator is made of a conventional porous polymer film commonly used, for example, polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer One porous polymer film may be used alone or in combination thereof, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting glass fibers, polyethylene terephthalate fibers, or the like may be used, but is not limited thereto.
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
실시예 1Example 1
(비수전해액 제조)(Non-aqueous electrolyte preparation)
1M LiPF6가 용해된 비수성 유기용매 (에틸렌 카보네이트(EC):디에틸 카보네이트(DEC)=3:7 부피비) 94g에 플루오로에틸렌카보네이트(FEC) 5g 및 상기 화학식 1a로 표시되는 화합물 1g을 첨가하여 본 발명의 비수전해액을 제조하였다 (하기 표 1 참조).5 g of fluoroethylene carbonate (FEC) and 1 g of the compound represented by Formula 1a were added to 94 g of a non-aqueous organic solvent (ethylene carbonate (EC): diethyl carbonate (DEC) = 3: 7 volume ratio) in which 1M LiPF 6 was dissolved. To prepare a non-aqueous electrolyte of the present invention (see Table 1 below).
(이차전지 제조)(Secondary Battery Manufacturing)
양극 활물질 입자로 리튬 코발트 복합산화물 (LiCoO2), 도전재로 카본 블랙 및 바인더로 폴리비닐리덴플루오라이드를 90 : 5 : 5 (wt%)의 비율로 용제인 N-메틸-2-피롤리돈 (NMP)에 첨가하여 양극 슬러리 (고형분 40%)를 제조하였다. 상기 양극 슬러리를 두께가 100㎛인 양극 집전체 (Al 박막)에 도포하고, 건조하고 롤 프레스(roll press)를 실시하고, 양극을 제조하였다.N-methyl-2-pyrrolidone as a solvent in a ratio of 90: 5: 5 (wt%) of lithium cobalt composite oxide (LiCoO 2 ) as a positive electrode active material, carbon black as a conductive material and polyvinylidene fluoride as a binder (NMP) was added to prepare a positive electrode slurry (40% solids). The positive electrode slurry was applied to a positive electrode current collector (Al thin film) having a thickness of 100 μm, dried, and roll pressed to prepare a positive electrode.
음극 활물질로 SiOx (0<x<1) 및 천연흑연(평균 입경(D50) 10 ㎛)과, 바인더로 폴리비닐리덴플루오라이드, 및 도전재로 카본 블랙을 10 : 85 : 2 : 3 (wt%)의 비율로 용제인 NMP에 첨가하여 음극 슬러리 (고형분 90%)를 제조하였다. 상기 음극 슬러리를 두께가 90㎛인 음극 집전체 (Cu 박막)에 도포하고, 건조하고 롤 프레스(roll press)를 실시하여 음극을 제조하였다..SiO x (0 <x <1) and natural graphite (average particle diameter (D50) 10 μm) as the negative electrode active material, polyvinylidene fluoride as the binder, and carbon black as the conductive material were 10: 85: 2: 3 (wt %) To a solvent, NMP, to prepare a negative electrode slurry (90% solids). The negative electrode slurry was applied to a negative electrode current collector (Cu thin film) having a thickness of 90 μm, dried, and subjected to roll press to prepare a negative electrode.
전술한 방법으로 제조한 양극과 음극을 폴리에틸렌 다공성 필름과 함께 적층하여 전극조립체를 제조한 다음, 이를 전지 케이스에 넣고 상기 제조된 비수전해액을 각각 주액하고, 밀봉하여 리튬 이차전지를 제조하였다.The positive electrode and the negative electrode prepared by the above-described method were laminated together with a polyethylene porous film to prepare an electrode assembly. Then, the prepared nonaqueous electrolyte was poured into the battery case, and the lithium secondary battery was prepared by sealing.
실시예Example 2 2
비수전해액 제조 시에, 화학식 1a의 화합물 대신 상기 화학식 2a의 화합물을 포함하는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 비수전해액 및 이를 포함하는 리튬 이차전지를 제조하였다.In preparing the non-aqueous electrolyte, a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except for including the compound of Formula 2a instead of the compound of Formula 1a.
실시예 3Example 3
비수전해액 제조 시에, 화학식 1a의 화합물 대신 상기 화학식 2b의 화합물을 포함하는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 비수전해액 및 이를 포함하는 리튬 이차전지를 제조하였다.In preparing the non-aqueous electrolyte, a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except for including the compound of Formula 2b instead of the compound of Formula 1a.
실시예 4Example 4
비수전해액 제조 시에, 화학식 1a의 화합물 대신 상기 화학식 1a의 화합물 0.5g 및 화학식 2a의 화합물 0.5g을 포함하는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 전해액 및 이를 포함하는 전지를 제조하였다.In preparing the non-aqueous electrolyte, an electrolyte solution and a battery including the same were prepared in the same manner as in Example 1, except that 0.5 g of the compound of Formula 1a and 0.5 g of the compound of Formula 2a were included instead of the compound of Formula 1a. .
실시예Example 5 5
비수전해액 제조 시에, 비수성 유기용매 80g에 플루오로에틸렌카보네이트(FEC) 10g 및 상기 화학식 1a로 표시되는 화합물 10g을 포함하는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 비수전해액 및 이를 포함하는 리튬 이차전지를 제조하였다.In preparing the non-aqueous electrolyte, the non-aqueous electrolyte and the same as in Example 1, except that 80g of the non-aqueous organic solvent includes 10g of fluoroethylene carbonate (FEC) and 10g of the compound represented by Formula 1a. To prepare a lithium secondary battery.
실시예Example 6 6
비수전해액 제조 시에, 비수성 유기용매 98.8g에 플루오로에틸렌카보네이트(FEC) 0.1g 및 상기 화학식 1a로 표시되는 화합물 0.1g을 포함하는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 비수전해액 및 이를 포함하는 리튬 이차전지를 제조하였다.In preparing the non-aqueous electrolyte, the non-aqueous electrolyte was prepared in the same manner as in Example 1, except that 98.8 g of the non-aqueous organic solvent contained 0.1 g of fluoroethylene carbonate (FEC) and 0.1 g of the compound represented by Formula 1a. And a lithium secondary battery comprising the same.
비교예 1Comparative Example 1
비수전해액 제조 시에, 플루오로에틸렌카보네이트(FEC)와 화학식 1a의 화합물을 모두 첨가하지 않는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 비수전해액 및 이를 포함하는 리튬 이차전지를 제조하였다.In preparing the non-aqueous electrolyte, a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except that neither fluoroethylene carbonate (FEC) nor the compound of Formula 1a were added.
비교예 2Comparative Example 2
비수전해액 제조 시에, 비수성 유기용매 95g에 플루오로에틸렌카보네이트(FEC) 5g을 포함하는 것을 제외하고는, 상기 실시예 1과 동일한 방법으로 비수전해액 및 이를 포함하는 리튬 이차전지를 제조하였다.In preparing the non-aqueous electrolyte, a non-aqueous electrolyte and a lithium secondary battery including the same were prepared in the same manner as in Example 1 except that 95 g of the non-aqueous organic solvent contained 5 g of fluoroethylene carbonate (FEC).
실험예Experimental Example
실험예 1. 사이클 수명 특성 평가Experimental Example 1. Evaluation of cycle life characteristics
실시예 1 내지 6, 비교예 1 및 2에서 제조된 전지를 각각 0.1C rate로 4.35V까지 정전류/정전압 조건 충전 및 0.05C cut off 충전을 실시하고, 0.1C 3.0V로 방전하였다. 이어서, 0.8C rate로 4.35V까지 정전류/정전압 조건 충전 및 0.05C cut off 충전을 실시하고, 0.5C, 3.0V로 방전하였다 (초기 방전 용량).The batteries prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were subjected to constant current / constant voltage condition charging and 0.05C cut off charging to 0.15C at 4.35V, respectively, and discharged at 0.1C to 3.0V. Subsequently, constant current / constant voltage condition charging and 0.05C cut off charging were performed up to 4.35V at 0.8C rate, and discharged at 0.5C and 3.0V (initial discharge capacity).
같은 조건으로 충방전을 200회 진행한 후 각 사이클에서의 방전 용량을 초기 방전량 대비하여 %로 하기 도 1에 나타내었다.After performing charge and discharge 200 times under the same conditions, the discharge capacity in each cycle is shown in FIG.
도 1에 나타난 바와 같이, 본원발명의 비수전해액을 구비한 실시예 1 내지 6의 이차전지의 경우, 사이클 수명 특성 저하가 서서히 일어나는 반면에, 비교예 1 및 2의 이차전지는 충방전을 100회 진행한 후부터 사이클 수명 특성이 급격히 저하되는 것을 확인할 수 있다. As shown in FIG. 1, in the case of the secondary batteries of Examples 1 to 6 having the nonaqueous electrolyte solution of the present invention, degradation of cycle life characteristics occurs gradually, whereas the secondary batteries of Comparative Examples 1 and 2 were charged and discharged 100 times. It can be seen that the cycle life characteristics deteriorate rapidly after the progress.
특히, 비수전해액 첨가제 성분으로 상기 화학식 1 및 2로 표시되는 화합물을 혼용하는 비수전해액을 구비한 실시예 4의 이차전지의 경우, 상기 화학식 1 또는 2로 표시되는 화합물을 단독으로 포함하는 비수전해액을 구비한 실시예 1 내지 3 및 5의 이차전지에 비하여 사이클 수명 특성이 보다 향상된 것을 알 수 있다. Particularly, in the case of the secondary battery of Example 4 having a non-aqueous electrolyte mixed with the compounds represented by Formulas 1 and 2 as the non-aqueous electrolyte additive component, the non-aqueous electrolyte containing the compound represented by Formula 1 or 2 alone It can be seen that the cycle life characteristics are more improved than the secondary batteries of Examples 1 to 3 and 5 provided.
실험예 2. 고온 저장 성능 측정Experimental Example 2 Measurement of High Temperature Storage Performance
실시예 1 내지 6, 비교예 1 내지 3에서 제조된 전지를 각각 0.1C rate로 4.35V까지 정전류/정전압 조건 충전 및 0.05C cut off 충전을 실시하고, 0.1C 3.0V로 방전하였다. 이어서, 0.8C rate로 4.35V까지 정전류/정전압 조건 충전 및 0.05C cut off 충전을 실시하고, 0.5C, 3.0V로 방전하였다 (초기 방전 용량).The batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to constant current / constant voltage condition charging and 0.05C cut off charging to 0.15C at 4.35V, respectively, and discharged at 0.1C to 3.0V. Subsequently, constant current / constant voltage condition charging and 0.05C cut off charging were performed up to 4.35V at 0.8C rate, and discharged at 0.5C and 3.0V (initial discharge capacity).
다시, 0.8C rate로 4.35V까지 정전류/정전압 조건 충전 및 0.05C cut off 충전을 실시하고, 60℃에서 2주간 보관하였다. 이후, 상온에서 0.5C, 3.0V로 방전하여 그 방전량을 측정하였다 (잔존 방전량).Again, constant current / constant voltage condition charging and 0.05C cut off charging were performed up to 4.35V at 0.8C rate and stored at 60 ° C. for 2 weeks. Then, it discharged at 0.5 C and 3.0V at normal temperature, and measured the discharge amount (remaining discharge amount).
다시 0.8C rate로 4.35V까지 정전류/정전압 조건 충전 및 0.05C cut off 충전, 0.5C 3.0V로 방전하여 그 방전량을 측정하였다 (회복 방전량).The charge was again measured at constant current / constant voltage conditions up to 4.35 V at 0.8 C rate, 0.05 C cut off charging, and discharge at 0.5 C 3.0 V (recovery discharge amount).
측정된 회복 방전 용량을 초기 방전량 대비하여 %로 하기 표 1에 나타내었다.The measured recovery discharge capacity is shown in Table 1 as% relative to the initial discharge amount.
Figure PCTKR2018000872-appb-T000001
Figure PCTKR2018000872-appb-T000001
상기 표 1에 나타난 바와 같이, 본원발명의 비수전해액을 구비한 실시예 1 내지 6의 이차전지의 경우, 플루오로에틸렌카보네이트 및 HF 제거제를 포함하지 않는 비수전해액을 구비한 비교예 1의 이차전지와, 플루오로에틸렌카보네이트만을 포함하는 비수전해액을 구비한 비교예 2의 이차전지에 비하여 잔존 방전량과 회복 방전량이 모두 우수한 것을 알 수 있다. As shown in Table 1, in the case of the secondary batteries of Examples 1 to 6 with the nonaqueous electrolyte solution of the present invention, the secondary battery of Comparative Example 1 with a nonaqueous electrolyte solution containing no fluoroethylene carbonate and a HF remover; It can be seen that both the residual discharge amount and the recovery discharge amount are superior to those of the secondary battery of Comparative Example 2 having a nonaqueous electrolyte containing only fluoroethylene carbonate.
특히, 비수전해액 첨가제 성분으로 상기 화학식 1 및 2로 표시되는 화합물을 혼용하는 비수전해액을 구비한 실시예 4의 이차전지의 경우, 상기 화학식 1 또는 2로 표시되는 화합물을 단독으로 포함하는 비수전해액을 구비한 실시예 1 내지 3 및 5의 이차전지에 비하여 잔존 방전량과 회복 방전량이 모두 우수한 것을 알 수 있다. Particularly, in the case of the secondary battery of Example 4 having a non-aqueous electrolyte mixed with the compounds represented by Formulas 1 and 2 as the non-aqueous electrolyte additive component, the non-aqueous electrolyte containing the compound represented by Formula 1 or 2 alone It can be seen that both the residual discharge amount and the recovery discharge amount are superior to the secondary batteries of Examples 1 to 3 and 5 provided.

Claims (12)

  1. 리튬염, Lithium Salt,
    제1 유기용매, First organic solvent,
    플루오로에틸렌 카보네이트; 및Fluoroethylene carbonate; And
    제1 첨가제로 하기 화학식 1 및 화학식 2로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상의 화합물;을 포함하는 것인 리튬 이차전지용 비수전해액.Non-aqueous electrolyte solution for a lithium secondary battery comprising a; at least one compound selected from the group consisting of compounds represented by the following formula (1) and (2) as a first additive.
    [화학식 1][Formula 1]
    Figure PCTKR2018000872-appb-I000022
    Figure PCTKR2018000872-appb-I000022
    상기 화학식 1에서,In Chemical Formula 1,
    R1 내지 R4는 각각 독립적으로 불소 원소로 치환 또는 비치환된 탄소수 1 내지 4의 알킬기이다.R 1 to R 4 are each independently an alkyl group having 1 to 4 carbon atoms unsubstituted or substituted with a fluorine element.
    [화학식 2][Formula 2]
    Figure PCTKR2018000872-appb-I000023
    Figure PCTKR2018000872-appb-I000023
    상기 화학식 2에서,In Chemical Formula 2,
    RF 1 내지 RF 6는 각각 독립적으로 불소 원소, 또는 불소 원소로 치환 또는 비치환된 탄소수 1 내지 3의 알킬기이고, R F 1 to R F 6 are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element,
    이때 상기 RF 1 내지 RF 6가 동시에 불소 원소는 아니다.In this case, R F 1 to R F 6 are not a fluorine element at the same time.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 플루오로에틸렌 카보네이트는 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 40중량%로 포함되는 것인 리튬 이차전지용 비수전해액.The fluoroethylene carbonate is a non-aqueous electrolyte solution for a lithium secondary battery that is contained in 0.1 to 40% by weight based on the total weight of the non-aqueous electrolyte.
  3. 청구항 1에 있어서,The method according to claim 1,
    상기 플루오로에틸렌 카보네이트는 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 30 중량%로 포함되는 것인 리튬 이차전지용 비수전해액.The fluoroethylene carbonate is a non-aqueous electrolyte lithium secondary battery that will be included in 0.1% to 30% by weight based on the total weight of the non-aqueous electrolyte.
  4. 청구항 1에 있어서,The method according to claim 1,
    상기 플루오로에틸렌 카보네이트는 비수전해액 전체 중량을 기준으로 5 중량% 내지 20 중량%로 포함되는 것인 리튬 이차전지용 비수전해액.The fluoroethylene carbonate is a non-aqueous electrolyte lithium secondary battery that is contained in 5 to 20% by weight based on the total weight of the non-aqueous electrolyte.
  5. 청구항 1에 있어서,The method according to claim 1,
    상기 화학식 1로 표시되는 화합물은 하기 화학식 1a 내지 화학식 1e로 표시되는 화합물들로 이루어진 군으로부터 선택된 적어도 하나 이상인 것인 리튬 이차전지용 비수전해액.The compound represented by Formula 1 is at least one or more selected from the group consisting of compounds represented by Formula 1a to Formula 1e Non-aqueous electrolyte for lithium secondary battery.
    [화학식 1a][Formula 1a]
    Figure PCTKR2018000872-appb-I000024
    Figure PCTKR2018000872-appb-I000024
    [화학식 1b][Formula 1b]
    Figure PCTKR2018000872-appb-I000025
    Figure PCTKR2018000872-appb-I000025
    [화학식 1c][Formula 1c]
    Figure PCTKR2018000872-appb-I000026
    Figure PCTKR2018000872-appb-I000026
    [화학식 1d][Formula 1d]
    Figure PCTKR2018000872-appb-I000027
    Figure PCTKR2018000872-appb-I000027
    [화학식 1e][Formula 1e]
    Figure PCTKR2018000872-appb-I000028
    Figure PCTKR2018000872-appb-I000028
  6. 청구항 1에 있어서,The method according to claim 1,
    상기 화학식 2로 표시되는 화합물에서, In the compound represented by Formula 2,
    RF 1 및 RF 2는 각각 독립적으로 불소 원소로 치환 또는 비치환된 탄소수 1 내지 3의 알킬기이고,R F 1 and R F 2 are each independently an alkyl group having 1 to 3 carbon atoms unsubstituted or substituted with a fluorine element,
    RF 3는 불소 원소 또는 불소 원소로 치환된 탄소수 1 내지 3의 알킬기이며,R F 3 is an fluorine element or an alkyl group having 1 to 3 carbon atoms substituted with a fluorine element,
    RF 4, RF 5 및 RF 6은 각각 독립적으로 불소 원소인 것인 리튬 이차전지용 비수전해액.R F 4 , R F 5 and R F 6 are each independently a fluorine element non-aqueous electrolyte for lithium secondary battery.
  7. 청구항 1에 있어서,The method according to claim 1,
    상기 화학식 2로 표시되는 화합물은 하기 화학식 2a 또는 화학식 2b로 표시되는 화합물인 것인 리튬 이차전지용 비수전해액.The compound represented by the formula (2) is a non-aqueous electrolyte lithium secondary battery that is a compound represented by the formula (2a) or (2b).
    [화학식 2a][Formula 2a]
    Figure PCTKR2018000872-appb-I000029
    Figure PCTKR2018000872-appb-I000029
    [화학식 2b][Formula 2b]
    Figure PCTKR2018000872-appb-I000030
    Figure PCTKR2018000872-appb-I000030
  8. 청구항 1에 있어서,The method according to claim 1,
    상기 제1 첨가제는 비수전해액 전체 중량을 기준으로 0.1 중량% 내지 10 중량%로 포함되는 것인 리튬 이차전지용 비수전해액.Wherein the first additive is a non-aqueous electrolyte lithium secondary battery containing 0.1 wt% to 10 wt% based on the total weight of the non-aqueous electrolyte.
  9. 청구항 8에 있어서,The method according to claim 8,
    상기 제1 첨가제는 비수전해액 전체 중량을 기준으로 1 중량% 내지 10 중량%로 포함되는 것인 리튬 이차전지용 비수전해액.The first additive is a non-aqueous electrolyte for a lithium secondary battery that is contained in 1 to 10% by weight based on the total weight of the non-aqueous electrolyte.
  10. 청구항 9에 있어서,The method according to claim 9,
    상기 제1 첨가제는 비수전해액 전체 중량을 기준으로 1 중량% 내지 7 중량%로 포함되는 것인 리튬 이차전지용 비수전해액.The first additive is a non-aqueous electrolyte for a lithium secondary battery that is contained in 1 to 7% by weight based on the total weight of the non-aqueous electrolyte.
  11. 양극활물질을 포함하는 양극, Positive electrode comprising a positive electrode active material,
    실리콘계 음극활물질을 포함하는 음극,A negative electrode containing a silicon-based negative electrode active material,
    상기 양극과 음극 사이에 개재된 분리막, 및A separator interposed between the positive electrode and the negative electrode, and
    청구항 1의 비수전해액을 포함하는 리튬 이차전지.A lithium secondary battery comprising the nonaqueous electrolyte of claim 1.
  12. 청구항 11에 있어서,The method according to claim 11,
    상기 음극활물질은 탄소계 음극활물질을 추가로 포함하는 것인 리튬 이차전지.The negative electrode active material is a lithium secondary battery further comprising a carbon-based negative electrode active material.
PCT/KR2018/000872 2017-01-26 2018-01-18 Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery comprising same WO2018139808A1 (en)

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