WO2018139808A1 - Électrolyte non aqueux pour accumulateur au lithium et accumulateur au lithium le comprenant - Google Patents

Électrolyte non aqueux pour accumulateur au lithium et accumulateur au lithium le comprenant Download PDF

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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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English (en)
Korean (ko)
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유성훈
이경미
김슬기
이현영
강유선
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주식회사 엘지화학
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Priority claimed from KR1020180006124A external-priority patent/KR102112207B1/ko
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to EP18745439.2A priority Critical patent/EP3404762B1/fr
Priority to CN201880001258.XA priority patent/CN108780923B/zh
Priority to PL18745439T priority patent/PL3404762T3/pl
Priority to US16/078,290 priority patent/US20190341654A1/en
Publication of WO2018139808A1 publication Critical patent/WO2018139808A1/fr

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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 Table
    • 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 Table
    • 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 Table
    • 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.

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Abstract

La présente invention porte sur un électrolyte non aqueux pour un accumulateur au lithium, l'électrolyte non aqueux comprenant un composé servant d'accepteur de HF, et sur un accumulateur au lithium, dont les caractéristiques de longévité et les caractéristiques d'accumulation à haute température sont améliorées par ce qu'il comprend l'électrolyte non aqueux.
PCT/KR2018/000872 2017-01-26 2018-01-18 Électrolyte non aqueux pour accumulateur au lithium et accumulateur au lithium le comprenant WO2018139808A1 (fr)

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EP18745439.2A EP3404762B1 (fr) 2017-01-26 2018-01-18 Électrolyte non-aqueux pour accumulateur au lithium et accumulateur au lithium le comprenant
CN201880001258.XA CN108780923B (zh) 2017-01-26 2018-01-18 用于锂二次电池的非水电解质溶液及包括所述非水电解质溶液的锂二次电池
PL18745439T PL3404762T3 (pl) 2017-01-26 2018-01-18 Niewodny elektrolit dla akumulatora litowego i zawierający go akumulator litowy
US16/078,290 US20190341654A1 (en) 2017-01-26 2018-01-18 Non-Aqueous Electrolyte Solution For Lithium Secondary Battery And Lithium Secondary Battery Including The Same

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KR1020180006124A KR102112207B1 (ko) 2017-01-26 2018-01-17 리튬 이차전지용 비수전해액 및 이를 포함하는 리튬 이차전지
KR10-2018-0006124 2018-01-17

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