WO2011081422A9 - Lithium composite oxide and a production method therefor - Google Patents

Lithium composite oxide and a production method therefor Download PDF

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WO2011081422A9
WO2011081422A9 PCT/KR2010/009456 KR2010009456W WO2011081422A9 WO 2011081422 A9 WO2011081422 A9 WO 2011081422A9 KR 2010009456 W KR2010009456 W KR 2010009456W WO 2011081422 A9 WO2011081422 A9 WO 2011081422A9
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lithium
composite oxide
oxide
lithium composite
tio
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French (fr)
Korean (ko)
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WO2011081422A3 (en
WO2011081422A2 (en
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신경
김직수
최문호
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주식회사 에코프로
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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 lithium composite oxide for a cathode active material of a lithium secondary battery and a method of manufacturing the same.
  • lithium secondary battery having a high energy density.
  • lithium cobalt oxide for example, LiCoO 2
  • Lithium cobalt oxide has a high potential for lithium, is excellent in safety, and relatively easy to synthesize.
  • LiNiO 2 lithium nickel oxide
  • Nickel is rich in resources, easy to reduce cost, and suitable for high capacity.
  • LiNiO 2 has a high capacity, but the crystal has low thermal stability, and there is room for improvement in cycle characteristics and high temperature storage characteristics. Therefore, the following proposal is made.
  • Japanese Laid-Open Patent Publication No. 2004-111076 discloses a general formula Li x Ni 1-yz Co y Mn z A a O 2 (wherein A is Fe, V, Cr, from the viewpoint of improving cycle characteristics and high temperature storage characteristics). At least one selected from the group consisting of Mn, Ti, Mg, Al, B and Ca, 0.05 ⁇ x ⁇ 1.10, 0.10 ⁇ y + z ⁇ 0.70, 0.05 ⁇ z ⁇ 0.40, 0 ⁇ a ⁇ 0.1)
  • a cathode active material having an electron conductivity of 10 ⁇ 4 ⁇ s ⁇ 10 ⁇ 1 S / has been proposed.
  • the active material of the composition which can obtain the improvement effect of cycling characteristics and high temperature storage characteristic has a problem that it is not practical because a capacity becomes small.
  • the present invention by improving the lithium nickel oxide for lithium secondary battery positive electrode active material to solve the above problems, a lithium secondary battery positive electrode active material having a cycle capacity and high temperature storage characteristics and at the same time having a high capacity lithium secondary battery comprising the same It aims to provide.
  • the present invention in the lithium composite oxide, SiO 2 , SnO 2 , Al 2 O 3 , TiO 2 , MgO, Fe 2 O 3 , Bi on the surface of the lithium composite oxide represented by the following formula (1) At least one oxide particle selected from 2 O 3 , Sb 2 O 3 , and ZrO 2 provides a lithium composite oxide coated by a dry coating method.
  • M is at least one kind of metal element selected from the group consisting of Al, Zn, Ti, V, Cr, Mn, Fe and Y)
  • the Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 At least one oxide selected from Al is 2 O 3 Or TiO 2 Being It provides a lithium composite oxide.
  • the lithium composite oxide represented by Formula 1 is composed of primary particles, the primary particles to form secondary particles, the average particle diameter of the primary particles is 0.1 ⁇ m 3 ⁇ m or less, The average particle diameter of the primary particles is 5 ⁇ m or more and 15 ⁇ m or less, and the tap density is 2.2 g / cm 3 or more and 2.8 g / cm 3 or less.
  • the present invention provides a lithium composite oxide of M in the lithium composite oxide represented by the formula (1).
  • the present invention also provides a lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte solution, wherein the positive electrode comprises a positive electrode active material comprising the lithium composite oxide.
  • the present invention also provides
  • Nickel-cobalt forming primary particles by forming coarse salts, nickel salts, and aluminum salts by mixing and extracting ammonia water as a complex and an alkali solution providing a hydroxyl group as a pH regulator, followed by extraction.
  • the present invention relates to a method for producing a lithium composite oxide, which comprises mixing one kind of oxide particles and performing a second heat treatment at 300 to 500 ° C. under an inert gas atmosphere.
  • the concentration of the aqueous ammonia solution provides a method for producing a lithium composite oxide of 30 to 60% of the concentration of the mixed aqueous solution of cobalt salt, nickel salt, aluminum salt. .
  • step i) the alkaline aqueous solution is preferably added so that the pH in the reactor is 9.0 to 11.5.
  • step iii) at least selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 It is preferable that one type of oxide particle has a size of 100 nm or less.
  • At least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 is Al. It provides a method for producing a lithium composite oxide, which is 2 O 3 or TiO 2 .
  • step iii) at least selected from SiO 2 , SnO 2 , Al 2 O 3 , TiO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 It is preferable that one type of oxide particles are mixed at 1 to 3% by weight relative to the lithium-containing composite oxide represented by the formula (1).
  • the concentration of the aqueous ammonia solution is preferably 30 to 60% of the concentration of the mixed aqueous solution of cobalt salt, nickel salt and aluminum salt.
  • the residence time in the reactor of the mixed aqueous solution of the cobalt salt, nickel salt and aluminum salt is preferably 12 to 24 hours.
  • the coating element-containing compound having a size of 100 nm or less formed on the surface of the active material of the present invention can reduce the internal resistance of the active material, thereby preventing the lowering of the discharge potential, thereby maintaining high discharge potential characteristics according to a change in current density (C-rate). Characteristics. Therefore, when the active material having such improved surface properties is applied to a battery, better life characteristics and lowering discharge potentials may be exhibited, thereby showing power improvement characteristics.
  • Figure 3 shows the rate characteristics of the coin cells made of the positive electrode active material of Examples 1 to 4 and Comparative Examples.
  • Figure 4 shows the life characteristics of the coin cells made of the positive electrode active material of Examples 1 to 4 and Comparative Examples.
  • Figure 5 shows the DSC characteristics of the coin cells made of the positive electrode active material of Examples 1 to 4 and Comparative Examples.
  • the positive electrode active material of the present invention is a) lithium composite oxide as the core particles and b) Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 coated thereon And at least one oxide particle selected from ZrO 2 .
  • the a) nickel-cobalt-aluminum composite hydroxide as the core particle may be prepared by coprecipitation using each metal-containing salt and a basic substance.
  • the coprecipitation method is a method of preparing two or more kinds of transition metal elements simultaneously by using a precipitation reaction in an aqueous solution.
  • a composite hydroxide containing two or more transition metals is prepared by mixing metal-containing salts in a desired molar ratio in consideration of the metal content to prepare an aqueous solution, followed by a strong base such as sodium hydroxide, and optionally ammonia. It may be prepared by adding an additive such as a source or the like and coprecipitation while keeping the pH basic. At this time, by appropriately controlling the temperature, pH, reaction time, slurry concentration, ion concentration, and the like, desired average particle diameter, particle diameter distribution, and particle density can be adjusted.
  • the pH range is 9-13 and preferably 10-12.
  • ammonia water and an alkaline solution are added to a mixed aqueous solution containing cobalt salt, nickel salt and aluminum salt.
  • the aqueous ammonia serves to control the shape of the complex hydroxide formed as a complex
  • the alkaline solution serves to maintain a pH suitable for coprecipitation in the mixed aqueous solution as a pH adjusting agent.
  • Preferred pH ranges are maintained to be basic as 10.5 to 11.5.
  • the metal-containing salt may be a sulfate or nitrate, preferably having an anion that is easily decomposed and volatilized upon firing.
  • nickel sulfate, cobalt sulfate, manganese sulfate, nickel nitrate, cobalt nitrate, manganese nitrate, and the like but are not limited thereto.
  • As a compound containing an aluminum salt only aluminum hydroxide, aluminum oxide, aluminum nitrate, aluminum fluoride, aluminum chloride, etc. may be mixed.
  • the alkaline solution may include sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like, preferably sodium hydroxide, but is not limited thereto.
  • additives and / or alkali carbonates which may form complexes with metal salts in the coprecipitation process may be further added.
  • an ammonium ion source for example, an ethylene diamine compound, a citric acid compound, or the like can be used.
  • the ammonium ion source include aqueous ammonia, aqueous ammonium sulfate solution and aqueous ammonium nitrate salt.
  • the alkali carbonate may be selected from the group consisting of ammonium carbonate, sodium carbonate, potassium carbonate and lithium carbonate. In some cases, these may be used by mixing two or more thereof.
  • the addition amount of the additive and alkali carbonate can be appropriately determined in consideration of the amount of transition metal-containing salt, pH, and the like.
  • the lithium composite according to the present invention is added to the spherical nickel-cobalt-aluminum metal composite hydroxide by adding a compound containing lithium and performing a first heat treatment at 600-800 ° C. under a dry air blowing condition and then cooling to room temperature. An oxide is formed.
  • the primary heat treatment is preferably performed at 600 ° C. or higher and 850 ° C. or lower, and more preferably 700 ° C. or higher and 800 ° C. or lower.
  • the firing time depends on the firing temperature, it is advantageous to control the shape of the particles, for example, for 10 to 20 hours in a dry air atmosphere.
  • the first heat treatment is performed at a temperature lower than 600 ° C., the reaction between the compounds used is not sufficient, and when the temperature is higher than 850 ° C., an unstable structure is formed by evaporation of Li in the crystal structure. have.
  • blowing gas it is also desirable to inject blowing gas at this time to increase the drying rate.
  • an inert gas such as nitrogen gas or argon gas may be preferably used as a gas having no CO 2 or moisture.
  • the drying rate can be increased by maintaining a vacuum instead of the blowing gas.
  • Lithium carbonate, lithium hydroxide, lithium nitrate, lithium sulfate, lithium oxide and the like can be used for the compound containing lithium.
  • lithium carbonate and lithium hydroxide are most advantageous in terms of environment and cost. It is preferable that the average particle diameter of the compound containing lithium is 5 micrometers or less. If the average particle diameter of the compound containing lithium is too large, the reaction may not proceed uniformly.
  • the cathode active material when the cathode active material is manufactured, it is synthesized using a solid phase synthesis method and a wet method.
  • the solid phase reaction method When the solid phase reaction method is used, starting materials for synthesizing the cathode active material and secondary phases generated at a low temperature remain at a high temperature. If the size of the particles used as a material is large, it is difficult to control the homogeneous distribution and size of the particles. In the present invention, however, the size of the particles to be coated and the post-coating heat treatment temperature are controlled to enable the synthesis of single particles even at low temperatures.
  • At least one oxide particle selected from 2 is mixed to be coated by the dry coating method.
  • the metal oxide coated on the surface suppresses the change of the crystal structure, thereby improving cycling stability during charge and discharge.
  • At least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 may be Al 2 O 3 , TiO 2.
  • the particle size was 100 nm or less to allow single particles to be synthesized even at a uniform coating and low temperature.
  • the mixing process for the dry coating method can be carried out by homogenizing for 1 to 3 hours using an automatic mixer.
  • Secondary heat treatment after coating is preferably performed at 300 to 500 °C. If the temperature is low, even coated oxides of 100 nm or less do not crystallize, and therefore, the application of the active material to the battery may interfere with the movement of lithium ions. In addition, when the heat treatment temperature is higher, the evaporation of lithium and the crystallinity of the metal oxide layer formed on the surface become high, which causes a problem in the movement of Li + .
  • the nonaqueous electrolyte secondary battery of the present invention is characterized by a positive electrode active material, and other components are not particularly limited.
  • the present invention provides a lithium secondary battery comprising a positive electrode active material prepared by the above manufacturing method.
  • the above-mentioned positive electrode active material may be mixed with other positive electrode active materials other than the positive electrode active material according to the present invention, and the present invention also provides a lithium secondary battery including such a positive electrode.
  • Methods for producing a lithium secondary battery by the construction of a positive electrode, a negative electrode, a separator, and a lithium salt-containing nonaqueous electrolyte are known in the art.
  • the positive electrode is prepared by applying a mixture of a positive electrode mixture of a positive electrode active material, a conductive agent and a binder and a ferroelectric material on a positive electrode current collector, and then drying it, and optionally adding a filler to the mixture. do.
  • the positive electrode current collector is generally made to a thickness of 3 to 500 ⁇ m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like may be used.
  • the current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
  • the conductive agent is typically added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material.
  • a conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery.
  • the conductive agent include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; 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 binder is a component that assists in bonding the active material and the conductive agent to the current collector, and is generally added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material.
  • 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 butylene rubber, fluorine rubber, various copolymers, and the like.
  • the filler is optionally used as a component for inhibiting expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery.
  • the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.
  • the negative electrode is produced by applying and drying the negative electrode material on the negative electrode current collector.
  • a conductive agent, a binder, a filler, or the like as in the positive electrode mixture may be optionally included.
  • the negative electrode current collector is generally made to a thickness of 3 to 500 ⁇ m.
  • a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery.
  • the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, aluminum-cadmium alloy, and the like can be used.
  • fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
  • the negative electrode material may be, for example, carbon such as hardly graphitized carbon or graphite carbon; Li x Fe 2 O 3 (0 ⁇ x ⁇ 1), Li x WO 2 (0 ⁇ x ⁇ 1), Sn x Mep 1-x Me ' y O z (Mep: Mn, Fe, Pb, Ge; Me' Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 ⁇ x ⁇ 1; 1 ⁇ y ⁇ 3; 1 ⁇ z ⁇ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO 2 , PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4
  • the separator is interposed between the cathode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used.
  • the pore diameter of the separator is generally from 0.01 to 10 ⁇ m ⁇ m, thickness is generally 5 ⁇ 300 ⁇ m.
  • a separator for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fibers or polyethylene are used.
  • a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.
  • the lithium salt-containing non-aqueous electrolyte consists of a nonaqueous electrolyte and lithium.
  • a nonaqueous electrolyte a nonaqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, and the like are used.
  • N-methyl- 2-pyrrolidinone a propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyl Low lactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxolon, aceto Nitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative , Aprotic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyroionate, ethyl propionate
  • organic solid electrolyte examples include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyedgetion lysine, polyester sulfides, polyvinyl alcohols, polyvinylidene fluorides, Polymers containing ionic dissociating groups and the like can be used.
  • Examples of the inorganic solid electrolyte include Li 3 N, LiI, Li 5 NI 2 , Li 3 N-LiI-LiOH, LiSiO 4 , LiSiO 4 -LiI-LiOH, Li 2 SiS 3 , Li 4 SiO 4 , Nitrides, halides, sulfates and the like of Li, such as Li 4 SiO 4 -LiI-LiOH, Li 3 PO 4 -Li 2 S-SiS 2 , and the like, may be used.
  • the lithium salt is a good material to dissolve in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2NLi, lithium chloroborane, lower aliphatic lithium carbonate, lithium tetraphenylborate, imide and the like can be used.
  • the non-aqueous electrolyte includes pyridine, triethyl phosphite, triethanol amine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, for the purpose of improving charge and discharge characteristics, flame retardancy, and the like.
  • halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high temperature storage characteristics.
  • the produced Ni-Co hydroxide overflowed, concentrated in a concentration tank connected to the overflow tube, circulated through the reaction tank, and 40 hours until the concentration of Ni-Co-Al hydroxide in the reaction tank and the settling tank became 4 mol / l.
  • the reaction was carried out.
  • the taken out suspension was washed with 5 times the amount of water using a filter press, and the Ni-Co-Al hydroxide concentration was adjusted to 2 mol / l.
  • the concentration of coexisting soluble salt in the filtrate immediately before the end of washing was confirmed by an infrared moisture meter, and the concentration was 15%.
  • Lithium hydroxide 784g was mixed with 3 kg of the obtained Ni-Co-Al coprecipitated hydroxide, and calcined at a temperature of 750 ° C for 10 hours in an atmosphere having an oxygen partial pressure of 0.5 atm, and a lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) Got.
  • the lithium nickel composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) thus obtained was mixed with 1 wt% of alumina (Al 2 O 3 ) particles having a size of 100 nm, and subjected to a solid phase reaction under inert gas N 2 injection, followed by 300 ° C. It baked in the oxygen atmosphere for 3 hours at the temperature of.
  • Example 1 1 wt% of Al 2 O 3 compared to lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) and coated by solid phase reaction, and then calcined at 500 ° C. for 3 hours to be the same as in Example 1 It was prepared by the method.
  • Example 3 NCA heat-treated at 300 with 1% weight titanium dioxide (TiO 2 )
  • TiO 2 was prepared in the same manner as in Example 1, except that 1 wt% of the lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) was added thereto to be coated by solid phase reaction.
  • 1 wt% of the lithium composite oxide LiNi 0.8 Co 0.15 Al 0.05 O 2
  • Example 4 NCA heat treated at 300 with 3% weight titanium dioxide (TiO 2 )
  • TiO 2 was prepared in the same manner as in Example 1, except that 3 wt% of the lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) was added and subjected to solid phase reaction.
  • 3 wt% of the lithium composite oxide LiNi 0.8 Co 0.15 Al 0.05 O 2
  • a lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) powder that was not coated as a cathode active material was used in the same manner as in Example 1.
  • the active material has a spherical active material of about 7 ⁇ m having uniform primary particles.
  • Examples 1 to 4 show a uniform particle shape as in Comparative Example, but the nano-sized coating material was uniformly coated on the surface, and it can be observed that the morphology changes as the amount of coating increases. have.
  • the cell obtained as described above is represented by [Li 2 MnO 4 / LiPF 6 (1 M) in EC +2 EMC / Li], and the rate (C-rate), life, and safety characteristics of the cell were evaluated.
  • FIG. 4 The evaluation of the life characteristics is shown in FIG. 4 by measuring the change in irreversible capacity with high temperature 60 cycles in the range of 3.4 to 4.3 V. As shown in FIG. 4, it can be seen that Examples 1 to 4 are excellent in high temperature cycle life characteristics because there is almost no capacity decrease with increasing cycle as compared with Comparative Example 1. These results indicate that Al 2 O 3 and TiO 2 coated on the surface of the active material suppress side reactions of residual lithium and electrolyte generated on the surface of the electrode as the battery cycle progresses, thereby minimizing the increase in resistance of the electrode, thereby preventing lithium consumption. It is thought that the lifespan performance is improved by giving.
  • the thermal stability of the active material prepared according to the present invention was evaluated by the following method.
  • Coin cells prepared according to Comparative Example 1 and Examples 1 to 4 were charged to the 4.5V and then disassembled in a dry room to separate the electrode plates.
  • About 10mg of the active material coated on the Al-foil was collected from the separated plate and about 10mg of the active material coated on the Al-foil was collected from the separated electrode plate. DSC analysis was performed.
  • DSC analysis was performed by scanning at an elevated temperature rate of 3 ° C./min in the temperature range between 100 ° C. and 300 ° C. in an air atmosphere. DSC analysis results are shown in FIG. 5.
  • the exothermic peak that appears as a result of DSC analysis is such a phenomenon that deteriorates the safety of the battery.
  • the area of the exothermic peak of the active material prepared according to Example 3 of the present invention was much reduced than that of Comparative Example 1. This reduction in heat generation results in the thermal stability of the positive electrode active material by suppressing side reactions of residual lithium and electrolyte generated on the surface of the electrode as Al 2 O 3 , TiO 2, etc. coated on the surface of the active material as the battery cycle progresses. To show that this is excellent.
  • the coating element-containing compound having a size of 100 nm or less formed on the surface of the active material can reduce the internal resistance of the active material, thereby preventing the lowering of the discharge potential, thereby maintaining high discharge potential characteristics according to the current density (C-rate) change. It can be usefully used as a lithium composite oxide for a cathode active material and a manufacturing method of a lithium secondary battery exhibiting characteristics.

Abstract

The present invention relates to a lithium composite oxide for use as an anode active material for a rechargeable lithium battery and to a production method therefor, and more specifically relates to an anode active material for a rechargeable lithium battery, comprising a lithium composite oxide in which a dry coating method is used in order to coat oxide particles of at least one type selected from SiO2, SnO2, Al2O3, TiO2, MgO, Fe2O3, Bi2O3, Sb2O3 and ZrO2 onto the surface of a lithium-nickel composite oxide represented by Chemical formula 1 below, and relates to a production method for the lithium composite oxide. [Chemical formula 1] LixNi1-y-zCoyMzO2 (where 0.98=x=1.1, 0.05=y=0.2, 0.05=z=0.2, and M is at least one type of metal element selected from the group consisting of Al, Zn, Ti, V, Cr, Mn, Fe and Y)

Description

리튬 복합 산화물 및 그 제조 방법.Lithium composite oxide and its manufacturing method.
본 출원은 2009년 12월 31일 한국특허청에 제출된 한국특허출원 제10-2009-135975호의 우선권을 청구하며, 본 명세서에서 참조로서 통합된다. This application claims the priority of Korean Patent Application No. 10-2009-135975, filed with the Korean Patent Office on December 31, 2009, which is incorporated herein by reference.
본 발명은 리튬 이차 전지의 양극활물질용 리튬 복합 산화물 및 그 제조 방법에 관한 것이다. The present invention relates to a lithium composite oxide for a cathode active material of a lithium secondary battery and a method of manufacturing the same.
모바일 기기에 대한 기술 개발과 수요가 증가함에 따라 에너지원으로서의 이차전지의 수요가 급격히 증가하고 있고, 그러한 이차전지 중 높은 에너지 밀도와 방전 전압의 리튬 이차전지에 대해 많은 연구가 행해져 왔고 또한 상용화되어 널리 사용되고 있다.As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Among them, many researches have been conducted and commercialized and widely used for lithium secondary batteries with high energy density and discharge voltage. It is used.
한편, 최근 환경문제에 대한 관심이 커짐에 따라 대기오염의 주요 원인의 하나인 가솔린 차량, 디젤 차량 등 화석연료를 사용하는 차량을 대체할 수 있는 전기자동차, 하이브리드 전기자동차에 대한 연구가 많이 진행되고 있다. 이러한 전기자동차, 하이브리드 전기자동차 등의 동력원으로서 리튬 이차전지를 사용하는 연구가 활발히 진행되고 있으며, 일부 상용화되어 사용되고 있다.Meanwhile, as interest in environmental problems has increased recently, researches on electric vehicles and hybrid electric vehicles, which can replace vehicles using fossil fuels such as gasoline and diesel vehicles, which are one of the main causes of air pollution, are being conducted. have. Research using a lithium secondary battery as a power source of such an electric vehicle, a hybrid electric vehicle, etc. has been actively conducted, and some commercialized and used.
근래에, 리튬함유 복합 산화물을 양극 활물질로서 포함하고, 탄소 재료, 실리콘 화합물, 주석 화합물 등을 음극 재료로서 포함한 전지가, 고에너지 밀도의 리튬 이차전지로서 주목을 받고 있다. 리튬함유 복합 산화물로서는, 리튬코발트 산화물(예를 들면 LiCoO2)가 실용화되어 있다. 리튬코발트 산화물은, 리튬에 대한 전위가 높고, 안전성이 뛰어나며, 비교적 합성이 용이하다.In recent years, a battery containing a lithium-containing composite oxide as a positive electrode active material and a carbon material, a silicon compound, a tin compound, and the like as a negative electrode material has attracted attention as a lithium secondary battery having a high energy density. As a lithium-containing composite oxide, lithium cobalt oxide (for example, LiCoO 2 ) has been put into practical use. Lithium cobalt oxide has a high potential for lithium, is excellent in safety, and relatively easy to synthesize.
코발트의 자원 문제를 회피하는 동시에, 더 큰 고용량을 목표로 하는 관점으로부터, 리튬니켈산화물(예를 들면 LiNiO2)을 실용화하는 시도가 이루어지고 있다. 니켈은 자원이 풍부하고, 저비용화가 용이하며, 고용량화에도 적합하다. 다만, LiNiO2는, 고용량을 갖지만, 결정의 열적 안정성이 낮고, 사이클 특성이나 고온 보존 특성에 개선의 여지가 있다. 따라서, 아래와 같은 제안이 이루어지고 있다.At the same time, attempts have been made to utilize lithium nickel oxide (for example, LiNiO 2 ) from the viewpoint of avoiding cobalt resource problems and aiming at a higher capacity. Nickel is rich in resources, easy to reduce cost, and suitable for high capacity. However, LiNiO 2 has a high capacity, but the crystal has low thermal stability, and there is room for improvement in cycle characteristics and high temperature storage characteristics. Therefore, the following proposal is made.
일본 특개평 5-242891호에는, LiNiO2의 열적 안정성을 개량하는 관점으로부터, LiNiO2에 Co와 Al를 첨가하는 것이 제안되어 있다. Co와 Al를 첨가한 리튬니켈 산화물은, 결정의 열적 안정성은 향상한다. 그러나, Co와 Al를 첨가한 리튬니켈 산화물을 이용했을 경우, LiCoO2를 이용했을 경우에 비해, 전지의 사이클 특성과 고온 보존 특성이 불충분하게 되기 쉽다. 사이클 특성이 낮아지는 원인은, 충전시에 있어서, Co와 Al를 첨가한 리튬니켈 산화물의 결정 안정성이 저하하는 점에 있다고 생각할 수 있다.In Japanese Patent Application Laid-Open No. 5-242891, in terms of improving the thermal stability of LiNiO 2, it has been proposed the addition of Co and Al to LiNiO 2. The lithium nickel oxide containing Co and Al improves the thermal stability of the crystal. However, when lithium nickel oxide containing Co and Al is used, the cycle characteristics and high temperature storage characteristics of the battery tend to be insufficient compared with the case of using LiCoO 2 . It may be considered that the cause of lowering cycle characteristics is that the crystal stability of lithium nickel oxide to which Co and Al are added decreases during charging.
[규칙 제91조에 의한 정정 21.03.2011]　
일본 특개 2004-111076호 공보에는, 사이클 특성이나 고온 보존 특성을 개량하는 관점으로부터, 일반식 LixNi1-y-zCoyMnzAaO2(식 중, A는, Fe, V, Cr, Mn, Ti, Mg, Al, B 및 Ca로 이루어진 군으로부터 선택되는 적어도 1종, 0.05≤x≤1.10, 0.10≤y+z≤0.70, 0.05≤z≤0.40, 0≤a≤0.1)로 표시되고, 전자전도도가 10-4≤s≤10 -1 S/인 양극 활물질이 제안되어 있다. 그러나, 사이클 특성과 고온 보존 특성의 개선 효과를 얻을 수 있는 조성의 활물질은, 용량이 작아지기 때문에 실용적이지 않다는 문제점이 있었다. [Revisions under Rule 91 21.03.2011]
Japanese Laid-Open Patent Publication No. 2004-111076 discloses a general formula Li x Ni 1-yz Co y Mn z A a O 2 (wherein A is Fe, V, Cr, from the viewpoint of improving cycle characteristics and high temperature storage characteristics). At least one selected from the group consisting of Mn, Ti, Mg, Al, B and Ca, 0.05 ≦ x ≦ 1.10, 0.10 ≦ y + z ≦ 0.70, 0.05 ≦ z ≦ 0.40, 0 ≦ a ≦ 0.1) A cathode active material having an electron conductivity of 10 −4 ≦ s ≦ 10 −1 S / has been proposed. However, the active material of the composition which can obtain the improvement effect of cycling characteristics and high temperature storage characteristic has a problem that it is not practical because a capacity becomes small.
본 발명은, 상기와 같은 과제를 해결하기 위해 리튬 이차전지 양극활물질용 리튬 니켈 산화물을 개량함으로써, 사이클 특성과 고온 보존 특성을 가진 동시에 고용량을 가진 리튬 이차 전지 양극활물질 및 이를 포함하는 리튬 이차 전지를 제공하는 것을 목적으로 한다.The present invention, by improving the lithium nickel oxide for lithium secondary battery positive electrode active material to solve the above problems, a lithium secondary battery positive electrode active material having a cycle capacity and high temperature storage characteristics and at the same time having a high capacity lithium secondary battery comprising the same It aims to provide.
본 발명은 상기 목적을 달성하기 위하여, 리튬 복합 산화물에 있어서, 하기 화학식 1로 표시되는 리튬 복합 산화물의 표면에 SiO2, SnO2, Al2O3, TiO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자가 건식 코팅법에 의하여 코팅된 리튬 복합 산화물을 제공한다. In order to achieve the above object, the present invention, in the lithium composite oxide, SiO 2 , SnO 2 , Al 2 O 3 , TiO 2 , MgO, Fe 2 O 3 , Bi on the surface of the lithium composite oxide represented by the following formula (1) At least one oxide particle selected from 2 O 3 , Sb 2 O 3 , and ZrO 2 provides a lithium composite oxide coated by a dry coating method.
[화학식 1][Formula 1]
LixNi1-y-zCoyMzO2 Li x Ni 1-yz Co y M z O 2
[규칙 제91조에 의한 정정 21.03.2011]　
(0.98≤x≤1.1, 0.1≤y≤0.35, 0.03≤z≤0.35, M은 Al, Zn, Ti, V, Cr, Mn, Fe 및 Y로 이루어지는 군으로부터 선택되는 적어도 일종의 금속 원소이다) [Revisions under Rule 91 21.03.2011]
(0.98≤x≤1.1, 0.1≤y≤0.35, 0.03≤z≤0.35, M is at least one kind of metal element selected from the group consisting of Al, Zn, Ti, V, Cr, Mn, Fe and Y)
본 발명에 있어서, 상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물은 Al2O3 또는 TiO2 인 것인 리튬 복합 산화물을 제공한다. In the present invention, the Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 At least one oxide selected from Al is2O3 Or TiO2Being It provides a lithium composite oxide.
여기서, 화학식 1로 표시되는 상기 리튬 복합 산화물은, 1차 입자로 이루어지고, 1차 입자는 2차 입자를 형성하며, 상기 1차 입자의 평균 입자지름은 0.1㎛ 이상 3㎛ 이하이고, 상기 2차 입자의 평균 입자지름은, 5㎛ 이상 15㎛ 이하이며, 탭밀도는, 2.2g/㎤이상, 2.8g/㎤ 이하인 것을 특징으로 한다. Here, the lithium composite oxide represented by Formula 1 is composed of primary particles, the primary particles to form secondary particles, the average particle diameter of the primary particles is 0.1㎛ 3㎛ or less, The average particle diameter of the primary particles is 5 µm or more and 15 µm or less, and the tap density is 2.2 g / cm 3 or more and 2.8 g / cm 3 or less.
또한, 본 발명은 상기 화학식 1로 표시되는 리튬 복합 산화물에 있어서, M 은 알루미늄인 리튬 복합 산화물을 제공한다. In addition, the present invention provides a lithium composite oxide of M in the lithium composite oxide represented by the formula (1).
본 발명은 또한, 양극, 음극, 양극과 음극의 사이에 개재한 세퍼레이터, 및 전해액을 구비하는 이차 전지로서, 양극이 상기의 리튬 복합 산화물로 이루어진 양극 활물질을 포함하는 리튬이온 이차 전지를 제공한다.      The present invention also provides a lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte solution, wherein the positive electrode comprises a positive electrode active material comprising the lithium composite oxide.
본 발명은 또한, The present invention also provides
i)코발트염, 니켈염, 알루미늄염의 혼합수용액에 착제로서 암모니아수와 pH 조절제로서 수산화기를 제공하는 알칼리용액을 첨가하고 공침시킨 후 추출함으로써 1차 입자가 뭉쳐져 부정형의 2차 입자를 이루고 있는 니켈-코발트-알루미늄 복합수산화물을 형성하는 단계, i) Nickel-cobalt forming primary particles by forming coarse salts, nickel salts, and aluminum salts by mixing and extracting ammonia water as a complex and an alkali solution providing a hydroxyl group as a pH regulator, followed by extraction. Forming an aluminum composite hydroxide,
ii) 상기 복합수산화물에 리튬화합물을 첨가하여 600-800 ℃에서 1차열처리하여 [화학식 1]로 표시되는 리튬 니켈 복합 산화물을 형성하는 단계, ii) adding a lithium compound to the composite hydroxide to form a lithium nickel composite oxide represented by [Formula 1] by primary heat treatment at 600-800 ° C.,
iii) 상기 화학식 1로 표시되는 리튬 복합 산화물과 상기 SiO2, SnO2, Al2O3, TiO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자를 혼합하고, 불활성 기체 분위기하에서 300 - 500 ℃에서 2차 열처리하는 단계를 포함하는 리튬 복합 산화물의 제조 방법에 관한 것이다.iii) at least one selected from the lithium composite oxide represented by Chemical Formula 1 and the SiO 2 , SnO 2 , Al 2 O 3 , TiO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 The present invention relates to a method for producing a lithium composite oxide, which comprises mixing one kind of oxide particles and performing a second heat treatment at 300 to 500 ° C. under an inert gas atmosphere.
본 발명에 있어서, 상기 i)단계에 있어서, 상기 암모니아 수용액의 농도는 코발트염, 니켈염, 알루미늄염의 혼합수용액 농도의 30 내지 60%인 것인 리튬 복합 산화물의 제조 방법을 제공한다. . In the present invention, in step i), the concentration of the aqueous ammonia solution provides a method for producing a lithium composite oxide of 30 to 60% of the concentration of the mixed aqueous solution of cobalt salt, nickel salt, aluminum salt. .
본 발명에 있어서, 상기 i)단계에 있어서, 상기 알칼리수용액은 반응기내의 pH가 9.0 내지 11.5가 되도록 투입하는 것이 바람직하다. In the present invention, in step i), the alkaline aqueous solution is preferably added so that the pH in the reactor is 9.0 to 11.5.
본 발명에 있어서, 상기 공정 iii)에 있어서, 상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자는 100 nm 이하의 크기를 갖는 것이 바람직하다. In the present invention, in the step iii), at least selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 It is preferable that one type of oxide particle has a size of 100 nm or less.
본 발명에 있어서, 상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자는 Al2O3 또는 TiO2 인 것인 리튬 복합 산화물의 제조 방법을 제공한다. In the present invention, at least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 is Al. It provides a method for producing a lithium composite oxide, which is 2 O 3 or TiO 2 .
본 발명에 있어서, 상기 공정 iii)에 있어서, 상기 SiO2, SnO2, Al2O3, TiO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자는 상기 화학식 1로 표시되는 리튬 함유 복합 산화물 대비 1 내지 3 중량 % 로 혼합되는 것이 바람직하다. In the present invention, in the step iii), at least selected from SiO 2 , SnO 2 , Al 2 O 3 , TiO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 It is preferable that one type of oxide particles are mixed at 1 to 3% by weight relative to the lithium-containing composite oxide represented by the formula (1).
본 발명에 있어서, 상기 공정 i)에 있어서, 상기 암모니아 수용액의 농도는 코발트염, 니켈염, 알루미늄염의 혼합수용액 농도의 30 내지 60%인 것이 바람직하다.  In the present invention, in the step i), the concentration of the aqueous ammonia solution is preferably 30 to 60% of the concentration of the mixed aqueous solution of cobalt salt, nickel salt and aluminum salt.
본 발명에 있어서, 상기 코발트염, 니켈염, 알루미늄염의 혼합수용액의 상기 반응기에서의 체류시간이 12~24 시간인 것이 바람직하다. In the present invention, the residence time in the reactor of the mixed aqueous solution of the cobalt salt, nickel salt and aluminum salt is preferably 12 to 24 hours.
본 발명의 활물질 표면에 형성된 100 nm 이하 크기의 코팅 원소 함유 화합물은 활물질의 내부저항을 작게 할 수 있어 방전 전위의 저하를 방지하여 전류밀도(C-rate) 변화에 따른 높은 방전 전위 특성을 유지하는 특성을 나타낸다. 따라서 이러한 표면 특성이 개선된 활물질을 전지에 적용할 경우, 보다 우수한 수명 특성과 방전 전위 저하 특성이 나타나 전력량(power) 향상 특성을 나타낼 수 있다.The coating element-containing compound having a size of 100 nm or less formed on the surface of the active material of the present invention can reduce the internal resistance of the active material, thereby preventing the lowering of the discharge potential, thereby maintaining high discharge potential characteristics according to a change in current density (C-rate). Characteristics. Therefore, when the active material having such improved surface properties is applied to a battery, better life characteristics and lowering discharge potentials may be exhibited, thereby showing power improvement characteristics.
도 1은 실시예 1 내지 4 및 비교예의 양극활물질의 XRD 패턴을 나타낸다. 1 shows XRD patterns of the positive electrode active materials of Examples 1 to 4 and Comparative Examples.
도 2는 실시예 1 내지 4 및 비교예의 양극활물질의 주사전자현미경 사진을 나타낸다. 2 shows scanning electron micrographs of the positive electrode active materials of Examples 1 to 4 and Comparative Examples.
도 3은 실시예 1 내지 4 및 비교예의 양극활물질로 만든 코인셀들의 율 특성을 나타낸다. Figure 3 shows the rate characteristics of the coin cells made of the positive electrode active material of Examples 1 to 4 and Comparative Examples.
도 4는 실시예 1 내지 4 및 비교예의 양극활물질로 만든 코인셀들의 수명 특성을 나타낸다. Figure 4 shows the life characteristics of the coin cells made of the positive electrode active material of Examples 1 to 4 and Comparative Examples.
도 5는 실시예 1 내지 4 및 비교예의 양극활물질로 만든 코인셀들의 DSC 특성을 나타낸다. Figure 5 shows the DSC characteristics of the coin cells made of the positive electrode active material of Examples 1 to 4 and Comparative Examples.
이하 본 발명에 대해 더욱 상세히 설명한다. Hereinafter, the present invention will be described in more detail.
본 발명의 양극 활물질은 a) 중심입자인 리튬 복합 산화물과 b) 이에 코팅된 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자를 포함한다.The positive electrode active material of the present invention is a) lithium composite oxide as the core particles and b) Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 coated thereon And at least one oxide particle selected from ZrO 2 .
상기 a) 중심입자인 니켈-코발트-알루미늄 복합수산화물은 각각의 금속 함유 염과 염기성 물질을 사용하여 공침법에 의해 제조될 수 있다.The a) nickel-cobalt-aluminum composite hydroxide as the core particle may be prepared by coprecipitation using each metal-containing salt and a basic substance.
상기 공침법은 수용액 중에서 침전 반응을 이용하여 2 종 이상의 전이 금속 원소를 동시에 침전시켜 제조하는 방법이다. 구체적인 예에서, 2 종 이상의 전이금속을 포함하는 복합수산화물은, 금속의 함량을 고려하여 금속 함유 염들을 소망하는 몰비로 혼합하여 수용액을 제조한 뒤, 수산화나트륨 등의 강염기와, 경우에 따라서는 암모니아 공급원 등의 첨가제 등을 부가하여, pH를 염기성으로 유지하면서 공침하여 제조될 수 있다. 이 때, 온도, pH, 반응 시간, 슬러리의 농도, 이온 농도 등을 적절히 제어함으로써, 소망하는 평균 입자 지름, 입자지름 분포, 입자 밀도를 조절할 수 있다. pH 범위는 9 내지 13이고 바람직하게는 10 내지 12이다.The coprecipitation method is a method of preparing two or more kinds of transition metal elements simultaneously by using a precipitation reaction in an aqueous solution. In a specific example, a composite hydroxide containing two or more transition metals is prepared by mixing metal-containing salts in a desired molar ratio in consideration of the metal content to prepare an aqueous solution, followed by a strong base such as sodium hydroxide, and optionally ammonia. It may be prepared by adding an additive such as a source or the like and coprecipitation while keeping the pH basic. At this time, by appropriately controlling the temperature, pH, reaction time, slurry concentration, ion concentration, and the like, desired average particle diameter, particle diameter distribution, and particle density can be adjusted. The pH range is 9-13 and preferably 10-12.
본 발명에 있어서, 먼저, 코발트염과 니켈염, 알루미늄염을 포함하는 혼합수용액에 암모니아수와 알칼리용액을 첨가한다. 여기서, 암모니아수는 착제로서 형성되는 복합수산화물의 형상을 조절하는 작용을 하며, 알칼리용액은 pH 조절제로서 상기 혼합 수용액에서 공침이 일어나기에 적합한 pH를 유지하는 작용을 한다. 바람직한 pH 범위는 10.5 내지 11.5 로서 염기성을 유지하도록 한다. In the present invention, first, ammonia water and an alkaline solution are added to a mixed aqueous solution containing cobalt salt, nickel salt and aluminum salt. Here, the aqueous ammonia serves to control the shape of the complex hydroxide formed as a complex, and the alkaline solution serves to maintain a pH suitable for coprecipitation in the mixed aqueous solution as a pH adjusting agent. Preferred pH ranges are maintained to be basic as 10.5 to 11.5.
상기 금속 함유 염은 소성시 용이하게 분해되고 휘발되기 쉬운 음이온을 갖는 것이 바람직한 바, 황산염 또는 질산염일 수 있다. 예를 들어, 황산 니켈, 황산 코발트, 황산 망간, 질산 니켈, 질산 코발트, 질산 망간 등을 들 수 있으나, 이에 한정되는 것은 아니다. 알루미늄염을 포함하는 화합물로서 수산화알루미늄, 산화알루미늄, 질산알루미늄, 불화알루미늄, 염화알루미늄 등을 혼합하는 것만으로도 좋다.The metal-containing salt may be a sulfate or nitrate, preferably having an anion that is easily decomposed and volatilized upon firing. For example, nickel sulfate, cobalt sulfate, manganese sulfate, nickel nitrate, cobalt nitrate, manganese nitrate, and the like, but are not limited thereto. As a compound containing an aluminum salt, only aluminum hydroxide, aluminum oxide, aluminum nitrate, aluminum fluoride, aluminum chloride, etc. may be mixed.
또한, 상기 알칼리 용액은 수산화나트륨, 수산화칼륨, 수산화리튬 등을 들 수 있고, 바람직하게는 수산화나트륨이 사용될 수 있으나, 이에 한정되는 것은 아니다.In addition, the alkaline solution may include sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like, preferably sodium hydroxide, but is not limited thereto.
하나의 바람직한 예에서, 상기 공침 과정에서 금속염과 착체를 형성할 수 있는 첨가제 및/또는 탄산 알칼리를 추가로 첨가할 수 있다. 상기 첨가제는, 예를 들어, 암모늄 이온 공급체, 에틸렌 디아민류 화합물, 구연산류 화합물 등이 사용될 수 있다. 상기 암모늄 이온 공급체는, 예를 들어, 암모니아수, 황산암모늄염 수용액, 질산암모늄염 수용액 등을 들 수 있다. 상기 탄산 알칼리는 탄산 암모늄,탄산나트륨,탄산 칼륨 및 탄산 리튬으로 이루어진 군에서 선택될 수 있다. 경우에 따라서는, 이들을 2 이상 혼합하여 사용할 수도 있다. In one preferred example, additives and / or alkali carbonates which may form complexes with metal salts in the coprecipitation process may be further added. As the additive, for example, an ammonium ion source, an ethylene diamine compound, a citric acid compound, or the like can be used. Examples of the ammonium ion source include aqueous ammonia, aqueous ammonium sulfate solution and aqueous ammonium nitrate salt. The alkali carbonate may be selected from the group consisting of ammonium carbonate, sodium carbonate, potassium carbonate and lithium carbonate. In some cases, these may be used by mixing two or more thereof.
상기 첨가제와 탄산 알칼리의 첨가량은 전이금속 함유 염의 양, pH 등을 고려하여 적절히 결정할 수 있다.The addition amount of the additive and alkali carbonate can be appropriately determined in consideration of the amount of transition metal-containing salt, pH, and the like.
공침 후 공침생성물을 추출하면 구상의 미세입자 (1차 입자)가 뭉쳐진 부정형 (2차 입자)의 니켈-코발트-알루미늄 금속의 복합수산화물이 형성된다. Extraction of the coprecipitation product after coprecipitation forms an amorphous (secondary particle) complex hydroxide of nickel-cobalt-aluminum metal in which spherical fine particles (primary particles) are aggregated.
상기 구형의 니켈-코발트-알루미늄 금속의 복합수산화물에 리튬을 포함하는 화합물을 첨가하고 건조 공기 블로잉(blowing) 조건에서 600-800 ℃에서 1차 열처리를 실시한 다음 상온으로 냉각하면 본 발명에 따른 리튬 복합산화물이 형성된다. The lithium composite according to the present invention is added to the spherical nickel-cobalt-aluminum metal composite hydroxide by adding a compound containing lithium and performing a first heat treatment at 600-800 ° C. under a dry air blowing condition and then cooling to room temperature. An oxide is formed.
상기 1차 열처리는 600 ℃이상, 850 ℃이하로 실시하는 것이 바람직하고, 700 ℃ 이상, 800 ℃ 이하로 실시하는 것이 더 바람직하다. 소성시간은, 소성온도에 따라 다르지만, 예를 들면 건조공기분위기에서 10 내지 20시간 동안 실시하는 것이 입자의 형상조절에 유리하다. 1차 열처리 공정을 600 ℃보다 낮은 온도에서 실시할 경우에는 사용하는 화합물간의 반응이 충분하지 않고, 850 ℃보다 높은 온도에서 실시할 경우에는 결정 구조 내의 Li의 증발에 의한 불안정한 구조가 형성되는 문제점이 있다. 또한, 1차 열처리 공정을 10 시간 미만의 시간으로 실시할 경우에는 결정화가 이루어지지 않는 문제점이 있고, 20 시간을 초과하는 시간 동안 실시할 경우에는 결정화가 과도하게 일어나거나 또는 결정 구조 내의 Li의 증발에 의한 불안정한 구조가 형성되는 문제점이 있다The primary heat treatment is preferably performed at 600 ° C. or higher and 850 ° C. or lower, and more preferably 700 ° C. or higher and 800 ° C. or lower. Although the firing time depends on the firing temperature, it is advantageous to control the shape of the particles, for example, for 10 to 20 hours in a dry air atmosphere. When the first heat treatment is performed at a temperature lower than 600 ° C., the reaction between the compounds used is not sufficient, and when the temperature is higher than 850 ° C., an unstable structure is formed by evaporation of Li in the crystal structure. have. In addition, when the first heat treatment process is carried out for less than 10 hours, there is a problem that the crystallization does not occur, and if it is performed for more than 20 hours, excessive crystallization occurs or evaporation of Li in the crystal structure There is a problem that an unstable structure is formed by
또한, 이때 건조 속도를 증가시키기 위하여 블로잉(blowing) 가스를 주입하는 것이 바람직하다. 상기 블로잉 가스로는 CO2 나 수분이 없는 가스로서 질소 가스 또는 아르곤 가스 등의 비활성 가스가 바람직하게 사용될 수 있다. 상기 블로잉 가스 대신 진공상태를 유지함으로써 건조 속도를 증가시킬 수 있다.It is also desirable to inject blowing gas at this time to increase the drying rate. As the blowing gas, an inert gas such as nitrogen gas or argon gas may be preferably used as a gas having no CO 2 or moisture. The drying rate can be increased by maintaining a vacuum instead of the blowing gas.
상기 리튬을 포함하는 화합물에는, 탄산리튬, 수산화리튬, 질산리튬, 황산리튬, 산화리튬 등을 이용할 수 있다. 그 중에서도 탄산리튬 및 수산화리튬이, 환경면과 비용면에서 가장 유리하다. 리튬을 포함하는 화합물의 평균 입자 지름은, 5㎛이하인 것이 바람직하다. 리튬을 포함하는 화합물의 평균 입자지름이 너무 크면, 반응이 균일하게 진행하지 않는 경우가 있다. Lithium carbonate, lithium hydroxide, lithium nitrate, lithium sulfate, lithium oxide and the like can be used for the compound containing lithium. Among them, lithium carbonate and lithium hydroxide are most advantageous in terms of environment and cost. It is preferable that the average particle diameter of the compound containing lithium is 5 micrometers or less. If the average particle diameter of the compound containing lithium is too large, the reaction may not proceed uniformly.
일반적으로 이러한 양극 활물질을 제조하는 경우 고상합성법과 습식법을 이용하여 합성하고 있는데, 고상반응법을 이용하는 경우, 양극 활물질을 합성하기 위한 출발물질과 저온에서 생성된 이차 상들이 고온에서도 남아 있게 되며, 출발물질로 사용된 입자들의 크기가 클 경우에는 입자의 균질한 분포와 크기를 제어하기가 어렵다. 그러나, 본 발명에 있어서는 코팅되는 입자의 크기와 코팅후 열처리 온도를 조절하여 낮은 온도에서도 단일 입자의 합성이 가능하도록 하는 것을 특징으로 한다.  In general, when the cathode active material is manufactured, it is synthesized using a solid phase synthesis method and a wet method. When the solid phase reaction method is used, starting materials for synthesizing the cathode active material and secondary phases generated at a low temperature remain at a high temperature. If the size of the particles used as a material is large, it is difficult to control the homogeneous distribution and size of the particles. In the present invention, however, the size of the particles to be coated and the post-coating heat treatment temperature are controlled to enable the synthesis of single particles even at low temperatures.
즉, 본원 발명에 있어서 얻어진 상기 리튬 니켈 복합 산화물에 크기가 100 nm 이하인 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자를 혼합하여 건식 코팅법에 의하여 코팅되도록 한다. 본원 발명에 있어서는 표면에 코팅된 금속 산화물이 결정 구조의 변화를 억제함으로써 충방전시 사이클링 안정성이 우수해진다. Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자는 Al2O3, TiO2 이며, 입자의 크기를 100 nm 이하로 함으로써 균일한 코팅 및 낮은 온도에서도 단일 입자의 합성이 가능하도록 하였다. Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자의 크기가 100 nm 이상일 경우 고온의 열처리를 필요로 하게 되므로 바람직하지 않다. That is, in the lithium nickel composite oxide obtained in the present invention, Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO having a size of 100 nm or less At least one oxide particle selected from 2 is mixed to be coated by the dry coating method. In the present invention, the metal oxide coated on the surface suppresses the change of the crystal structure, thereby improving cycling stability during charge and discharge. At least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 may be Al 2 O 3 , TiO 2. The particle size was 100 nm or less to allow single particles to be synthesized even at a uniform coating and low temperature. High temperature when the size of at least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 is 100 nm or more It is not preferable because it requires heat treatment of.
건식 코팅법을 위한 혼합 공정은 오토매틱혼합기(automatic mixer)를 사용하여 1 내지 3시간 동안 균질화하여 실시할 수 있다.  The mixing process for the dry coating method can be carried out by homogenizing for 1 to 3 hours using an automatic mixer.
코팅후 2차 열처리는 300 내지 500 ℃에서 하는 것이 바람직하다. 온도가 낮으면 100 nm 이하의 코팅된 산화물이라도 결정화되지 않으므로 이 활물질을 전지에 적용하면 리튬 이온의 이동이 방해를 받을 수 있다. 또한, 열처리 온도가 보다 높으면 리튬의 증발 및 표면에 형성된 금속 산화물 층의 결정도가 높아져 Li+ 의 이동에 문제가 생기게 된다. Secondary heat treatment after coating is preferably performed at 300 to 500 ℃. If the temperature is low, even coated oxides of 100 nm or less do not crystallize, and therefore, the application of the active material to the battery may interfere with the movement of lithium ions. In addition, when the heat treatment temperature is higher, the evaporation of lithium and the crystallinity of the metal oxide layer formed on the surface become high, which causes a problem in the movement of Li + .
아울러 열처리 시간이 상기 범위를 벗어나는 경우 리튬의 증발 및 표면에 형성된 금속 산화물 층의 결정도가 높아져 Li+ 의 이동에 문제가 생기게 된다.In addition, when the heat treatment time is out of the above range, the evaporation of lithium and the crystallinity of the metal oxide layer formed on the surface become high, thereby causing a problem in the movement of Li + .
이렇게 제조된 리튬 복합산화물을 활물질로 하는 양극을 제조하는 방법은 특별히 제한되지 않으므로, 통상적으로 이용되는 방법을 그대로 적용할 수 있다. 또한, 이렇게 제조된 양극을 이용하여 리튬 이온 이차전지를 제조하는데 있어서도, 통상적인 방법이 그대로 이용될 수 있다. 본 발명의 비수전해액 이차전지는, 양극 활물질에 특징이 있으며, 다른 구성요소는 특별히 제한되지 않는다.Since the method for producing the positive electrode using the lithium composite oxide prepared as an active material is not particularly limited, a method commonly used may be applied as it is. In addition, in manufacturing a lithium ion secondary battery using the positive electrode thus prepared, a conventional method may be used as it is. The nonaqueous electrolyte secondary battery of the present invention is characterized by a positive electrode active material, and other components are not particularly limited.
또한 본 발명은 상기 제조 방법으로 제조된 양극 활물질을 포함하는 리튬 2 차 전지를 제공한다.In another aspect, the present invention provides a lithium secondary battery comprising a positive electrode active material prepared by the above manufacturing method.
비가역 용량을 조절하기 위하여 위에서 언급된 양극 활물질을 본 발명에 따른 양극 활물질 이외의 다른 양극 활물질과 혼합하여 사용할 수 있으며, 본 발명은 또한 이러한 양극을 포함하는 리튬 이차전지를 제공한다. 양극, 음극, 분리막, 및 리튬염 함유 비수 전해질의 구성에 의해 리튬 이차전지를 제조하는 방법은 당업계에 공지되어 있다.In order to control the irreversible capacity, the above-mentioned positive electrode active material may be mixed with other positive electrode active materials other than the positive electrode active material according to the present invention, and the present invention also provides a lithium secondary battery including such a positive electrode. Methods for producing a lithium secondary battery by the construction of a positive electrode, a negative electrode, a separator, and a lithium salt-containing nonaqueous electrolyte are known in the art.
양극은, 앞서 설명한 바와 같이, 양극 집전체 상에 양극 활물질, 도전제 및 결착제의 양극 합제와 강유전체 물질의 혼합물을 도포한 후 건조하여 제조되며, 필요에 따라서는 상기 혼합물에 충진제를 더 첨가하기도 한다.As described above, the positive electrode is prepared by applying a mixture of a positive electrode mixture of a positive electrode active material, a conductive agent and a binder and a ferroelectric material on a positive electrode current collector, and then drying it, and optionally adding a filler to the mixture. do.
상기 양극 집전체는 일반적으로 3 내지 500 ㎛의 두께로 만든다. 이러한 양극 집전체는, 당해 전지에 화학적 변화를 유발하지 않으면서 높은 도전성을 가지는 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 스테인레스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 또는 알루미늄이나 스테리인레스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면처리한 것 등이 사용될 수 있다. 집전체는 그것의 표면에 미세한 요철을 형성하여 양극 활물질의 접착력을 높일 수도 있으며, 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태가 가능하다.The positive electrode current collector is generally made to a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like may be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
상기 도전제는 통상적으로 양극 활물질을 포함한 혼합물 전체 중량을 기준으로 1 내지 50 중량%로 첨가된다. 이러한 도전제는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 천연 흑연이나 인조 흑연 등의 흑연; 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서머 블랙 등의 카본블랙; 탄소 섬유나 금속 섬유 등의 도전성 섬유; 불화 카본, 알루미늄, 니켈 분말 등의 금속 분말; 산화아연, 티탄산 칼륨 등의 도전성 위스키; 산화 티탄 등의 도전성 금속 산화물; 폴리페닐렌 유도체 등의 도전성 소재 등이 사용될 수 있다.The conductive agent is typically added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material. Such a conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery. Examples of the conductive agent include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; 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 결착제는 활물질과 도전제 등의 결합과 집전체에 대한 결합에 조력하는 성분으로서, 통상적으로 양극 활물질을 포함하는 혼합물 전체 중량을 기준으로 1 내지 50 중량%로 첨가된다. 이러한 결착제의 예로는, 폴리불화비닐리덴, 폴리비닐알코올, 카르복시메틸셀룰로우즈(CMC), 전분, 히드록시프로필셀룰로우즈, 재생 셀룰로우즈, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 에틸렌-프로필렌-디엔 테르 폴리머(EPDM), 술폰화 EPDM, 스티렌 브티렌 고무, 불소 고무, 다양한 공중합체 등을 들 수 있다.The binder is a component that assists in bonding the active material and the conductive agent to the current collector, and is generally added in an amount of 1 to 50 wt% based on the total weight of the mixture including the positive electrode active material. 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 butylene rubber, fluorine rubber, various copolymers, and the like.
상기 충진제는 양극의 팽창을 억제하는 성분으로서 선택적으로 사용되며, 당해 전지에 화학적 변화를 유발하지 않으면서 섬유상 재료라면 특별히 제한되는 것은 아니며, 예를 들어, 폴리에틸렌, 폴리프로필렌 등의 올리핀계 중합체; 유리섬유, 탄소섬유 등의 섬유상 물질이 사용된다.The filler is optionally used as a component for inhibiting expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples of the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.
반면에, 음극은 음극 집전체 상에 음극 재료를 도포, 건조하여 제작된다. 경우에 따라서는, 양극 합제에서와 같은 도전제, 결착제, 충진제 등이 선택적으로 포함될 수도 있다.On the other hand, the negative electrode is produced by applying and drying the negative electrode material on the negative electrode current collector. In some cases, a conductive agent, a binder, a filler, or the like as in the positive electrode mixture may be optionally included.
상기 음극 집전체는 일반적으로 3 내지 500 ㎛의 두께로 만들어진다. 이러한 음극 집전체는, 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 구리, 스테인레스 스틸, 알루미늄,니켈, 티탄, 소성 탄소, 구리나 스테인레스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면처리한 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 is generally made to a thickness of 3 to 500 ㎛. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, 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.
[규칙 제91조에 의한 정정 21.03.2011]　
상기 음극 재료는, 예를 들어, 난흑연화 탄소, 흑연계 탄소 등의 탄소; LixFe2O3(0≤x≤1), LixWO2(0≤x≤1), SnxMep1-xMe'yOz (Mep: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, 주기율표의 1족, 2족, 3족 원소, 할로겐; 0<x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 및 Bi2O5 등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni계 재료 등을 사용할 수 있다. [Revisions under Rule 91 21.03.2011]
The negative electrode material may be, for example, carbon such as hardly graphitized carbon or graphite carbon; Li x Fe 2 O 3 (0 ≦ x ≦ 1), Li x WO 2 (0 ≦ x ≦ 1), Sn x Mep 1-x Me ' y O z (Mep: Mn, Fe, Pb, Ge; Me' Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 <x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO 2 , PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 and Metal oxides such as Bi 2 O 5 ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.
상기 분리막은 음극과 음극 사이에 개재되며, 높은 이온 투과도와 기계적 강도를 가지는 절연성의 얇은 박막이 사용된다.The separator is interposed between the cathode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used.
분리막의 기공 직경은 일반적으로 0.01 ~ 10 ㎛이고, 두께는 일반적으로 5 ~ 300 ㎛이다. 이러한 분리막으로는, 예를 들어, 내화학성 및 소수성의 폴리프로필렌 등의 올레핀계 폴리머; 유리섬유 또는 폴리에틸렌 등으로 만들어진 시트나 부직포 등이 사용된다. 전해질로서 폴리머 등의 고체 전해질이 사용되는 경우에는 고체 전해질이 분리막을 겸할 수도 있다.The pore diameter of the separator is generally from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛. As such a separator, for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fibers or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.
리튬염 함유 비수계 전해질은, 비수 전해질과 리튬으로 이루어져 있다. 비수 전해질로는 비수 전해액, 고체 전해질, 무기 고체 전해질 등이 사용된다.The lithium salt-containing non-aqueous electrolyte consists of a nonaqueous electrolyte and lithium. As the nonaqueous electrolyte, a nonaqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, and the like are used.
상기 비수 전해액으로는, 예를 들어, N-메틸-2-피롤리디논, 프로필렌 카르보네이트, 에틸렌 카르보네이트, 부틸렌 카르보네이트, 디메틸 카르보네이트, 디에틸 카르보네이트, 감마-부틸로 락톤, 1,2-디메톡시 에탄, 테트라히드록시 프랑(franc), 2-메틸 테트라하이드로푸란, 디메틸술폭시드, 1,3-디옥소런, 포름아미드, 디메틸포름아미드, 디옥소런, 아세토니트릴, 니트로메탄, 포름산 메틸, 초산메틸, 인산 트리에스테르, 트리메톡시 메탄, 디옥소런 유도체, 설포란, 메틸 설포란, 1,3-디메틸-2-이미다졸리디논, 프로필렌 카르보네이트 유도체, 테트라하이드로푸란 유도체, 에테르, 피로피온산 메틸,프로피온산 에틸 등의 비양자성 유기용매가 사용될 수 있다.As said non-aqueous electrolyte, N-methyl- 2-pyrrolidinone, a propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyl Low lactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxolon, aceto Nitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative , Aprotic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyroionate, ethyl propionate and the like can be used.
상기 유기 고체 전해질로는, 예를 들어, 폴리에틸렌 유도체, 폴리에틸렌 옥사이드 유도체, 폴리프로필렌 옥사이드 유도체, 인산 에스테르 폴리머, 폴리 에지테이션 리신(agitation lysine), 폴리에스테르 술파이드, 폴리비닐 알코올, 폴리 불화 비닐리덴, 이온성 해리기를 포함하는 중합체 등이 사용될 수 있다.Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyedgetion lysine, polyester sulfides, polyvinyl alcohols, polyvinylidene fluorides, Polymers containing ionic dissociating groups and the like can be used.
상기 무기 고체 전해질로는, 예를 들어, Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2 등의 Li의 질화물, 할로겐화물, 황산염 등이 사용될 수 있다.Examples of the inorganic solid electrolyte include Li 3 N, LiI, Li 5 NI 2 , Li 3 N-LiI-LiOH, LiSiO 4 , LiSiO 4 -LiI-LiOH, Li 2 SiS 3 , Li 4 SiO 4 , Nitrides, halides, sulfates and the like of Li, such as Li 4 SiO 4 -LiI-LiOH, Li 3 PO 4 -Li 2 S-SiS 2 , and the like, may be used.
상기 리튬염은 상기 비수계 전해질에 용해되기 좋은 물질로서, 예를 들어, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2) 2NLi, 클로로 보란 리튬, 저급 지방족 카르본산 리튬, 4 페닐 붕산 리튬, 이미드 등이 사용될 수 있다.The lithium salt is a good material to dissolve in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2NLi, lithium chloroborane, lower aliphatic lithium carbonate, lithium tetraphenylborate, imide and the like can be used.
또한, 비수계 전해질에는 충방전 특성, 난연성 등의 개선을 목적으로, 예를 들어, 피리딘, 트리에틸포스파이트, 트리에탄올 아민, 환상 에테르, 에틸렌 디아민, n-글라임(glyme), 헥사 인산 트리 아미드, 니트로벤젠 유도체, 유황, 퀴논 이민 염료, N-치환 옥사졸리디논, N,N-치환 이미다졸리딘, 에틸렌 글리콜 디알킬 에테르, 암모늄염, 피롤, 2-메톡시 에탄올, 삼염화 알루미늄 등이 첨가될 수도 있다. 경우에 따라서는, 불연성을 부여하기 위하여, 사염화탄소, 삼불화에틸렌 등의 할로겐 함유 용매를 더 포함시킬 수도 있고, 고온 보존 특성을 향상시키기 위하여 이산화탄산 가스를 더 포함시킬 수도 있다.In addition, the non-aqueous electrolyte includes pyridine, triethyl phosphite, triethanol amine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, for the purpose of improving charge and discharge characteristics, flame retardancy, and the like. Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride, etc. It may be. In some cases, in order to impart nonflammability, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high temperature storage characteristics.
이하에서는 실시예를 통해 본 발명의 내용을 상술하지만, 본 발명의 범주가 그것에 의해 한정되는 것은 아니다.Hereinafter, the present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.
[규칙 제91조에 의한 정정 21.03.2011]　
<실시예 1> 1% 중량 알루미나(Al2O3)로 300 °C에서 열처리된 리튬 복합 화합물 제조 [Revisions under Rule 91 21.03.2011]
Example 1 Preparation of a lithium composite compound heat-treated at 300 ° C. with 1% weight alumina (Al 2 O 3 )
2 mol/l의 황산니켈, 황산코발트, 질산 알루미늄을 Ni:Co:Al=80:15:5 이 되도록 혼합한 수용액과 5.0 mol/l 암모니아수 용액을 동시에 반응조 내에 공급하였다. An aqueous solution of 5.0 mol / l ammonia water solution and a mixture of 2 mol / l nickel sulfate, cobalt sulfate, and aluminum nitrate such that Ni: Co: Al = 80: 15: 5 were simultaneously supplied into the reactor.
반응조는 날개형 교반기로 항상 교반을 행하고, 동시에 pH=11.5±5 로 되도록 2 mol/l의 수산화나트륨 수용액을 자동 공급하였다. 생성한 Ni-Co 수산화물은 오버플로우되어, 오버플로우관에 연결된 농축조에서 농축하고, 반응조에 순환을 행하고, 반응조와 침강조 중의 Ni-Co-Al 수산화물 농도가 4 mol/l이 될 때까지 40시간 반응을 행하였다. The reactor was always stirred with a blade type stirrer, and at the same time, an aqueous solution of 2 mol / l sodium hydroxide was automatically supplied to pH = 11.5 ± 5. The produced Ni-Co hydroxide overflowed, concentrated in a concentration tank connected to the overflow tube, circulated through the reaction tank, and 40 hours until the concentration of Ni-Co-Al hydroxide in the reaction tank and the settling tank became 4 mol / l. The reaction was carried out.
반응 후, 취출한 현탁액을 필터 프레스를 이용하여 5 배량의 물로 수세를 행한 후, Ni-Co-Al 수산화물 농도가 2 mol/l가 되도록 하였다. 수세 종료 직전의 여과액 내의 공존 가용성염 농도를 적외 수분계로 확인한 바, 농도는 15%였다.  After the reaction, the taken out suspension was washed with 5 times the amount of water using a filter press, and the Ni-Co-Al hydroxide concentration was adjusted to 2 mol / l. The concentration of coexisting soluble salt in the filtrate immediately before the end of washing was confirmed by an infrared moisture meter, and the concentration was 15%.
이 현탁액을, 필터 프레스를 이용하여 Ni-Co 수산화물 입자의 중량에 대하여 10배의 물에 의해 수세를 행한 후, 건조를 행하여, Ni:Co:Al=80:15:5의 Ni-Co-Al 수산화물 입자를 얻었다.  After washing this suspension with water 10 times with respect to the weight of Ni-Co hydroxide particle | grains using a filter press, it is dried and Ni-Co-Al of Ni: Co: Al = 80: 15: 5. Hydroxide particles were obtained.
[규칙 제91조에 의한 정정 21.03.2011]　
얻어진 Ni-Co-Al 공침 수산화물 3kg에, 수산화리튬 784g을 혼합하여, 산소분압이 0.5 기압인 분위기중에서, 750 ℃의 온도에서 10시간 소성하여, 리튬 복합산화물(LiNi0.8Co0.15Al0.05O2)을 얻었다. [Revisions under Rule 91 21.03.2011]
Lithium hydroxide 784g was mixed with 3 kg of the obtained Ni-Co-Al coprecipitated hydroxide, and calcined at a temperature of 750 ° C for 10 hours in an atmosphere having an oxygen partial pressure of 0.5 atm, and a lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) Got.
이와 같이 얻어진 리튬니켈 복합산화물(LiNi0.8Co0.15Al0.05O2)에 100 nm 크기의 알루미나(Al2O3) 입자를 1 중량% 혼합하고, 불활성 가스 N2 주입하에 고상 반응 시킨 후, 300 ℃의 온도에서 3시간 산소 분위기에서 소성하였다. The lithium nickel composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) thus obtained was mixed with 1 wt% of alumina (Al 2 O 3 ) particles having a size of 100 nm, and subjected to a solid phase reaction under inert gas N 2 injection, followed by 300 ° C. It baked in the oxygen atmosphere for 3 hours at the temperature of.
[규칙 제91조에 의한 정정 21.03.2011]　
<실시예 2> 1 중량% 알루미나(Al2O3)로 500°C에서 열처리된 NCA [Revisions under Rule 91 21.03.2011]
Example 2 NCA heat treated at 500 ° C. with 1 wt% alumina (Al 2 O 3 )
Al2O3를 리튬 복합산화물(LiNi0.8Co0.15Al0.05O2) 대비 1 중량% 첨가하고 고상 반응시켜 코팅되도록 한 후, 500 ℃의 온도에서 3시간 소성한 것을 제외하고는 실시예 1과 동일한 방법으로 제조하였다. 1 wt% of Al 2 O 3 compared to lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) and coated by solid phase reaction, and then calcined at 500 ° C. for 3 hours to be the same as in Example 1 It was prepared by the method.
<실시예 3> 1% 중량 이산화티탄(TiO2)로 300에서 열처리된 NCA Example 3 NCA heat-treated at 300 with 1% weight titanium dioxide (TiO 2 )
TiO2를 리튬 복합산화물(LiNi0.8Co0.15Al0.05O2) 대비 1 중량% 첨가하고 고상 반응시켜 코팅되도록 한 것을 제외하고는 실시예 1과 동일한 방법으로 제조하였다. TiO 2 was prepared in the same manner as in Example 1, except that 1 wt% of the lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) was added thereto to be coated by solid phase reaction.
<실시예 4> 3% 중량 이산화티탄(TiO2)로 300에서 열처리된 NCA Example 4 NCA heat treated at 300 with 3% weight titanium dioxide (TiO 2 )
TiO2를 리튬 복합산화물(LiNi0.8Co0.15Al0.05O2) 대비 대비 3 중량% 첨가하고 고상 반응 시켜 코팅되도록 한 것을 제외하고는 실시예 1과 동일한 방법으로 제조하였다. TiO 2 was prepared in the same manner as in Example 1, except that 3 wt% of the lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) was added and subjected to solid phase reaction.
<비교예 1>Comparative Example 1
양극 활물질로서 코팅되지 않은 리튬 복합산화물(LiNi0.8Co0.15Al0.05O2) 분말을 그대로 사용한 것을 제외하고는 실시예 1과 동일한 방법으로 제조하였다. A lithium composite oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) powder that was not coated as a cathode active material was used in the same manner as in Example 1.
상기의 과정을 통해 제조된 실시예 1 내지 2 및 비교예의 양극활물질의 XRD 패턴은 도 1에, 주사전자현미경 사진은 도 2에 나타내었다. XRD patterns of the positive electrode active materials of Examples 1 to 2 and Comparative Examples prepared through the above process are shown in FIG. 1, and scanning electron micrographs are shown in FIG. 2.
도 1에서 보는 바와 같이 X-선 회절분석 결과 코팅된 리튬니켈복합산화물 및 코팅되지 않은 비교예의 활물질 모두 R3m 구조를 가지고 있으며, 단일상이 잘 형성됨을 확인할 수 있었다. 이는 코팅으로 이해 활물질 자체 구조에는 영향을 미치지 않는 다는 것을 나타낸다. As shown in FIG. 1, X-ray diffraction analysis showed that both the coated lithium nickel composite oxide and the uncoated active material had an R3m structure, and the single phase was well formed. This indicates that the coating does not affect the structure of the active material itself.
또한, 도 2의 주사전자현미경 사진에서 보는 바와 같이 비교예의 코팅되지 않은 리튬니켈복합산화물의 경우 균일한 1차 입자를 가지는 약 7 um 의 구형의 활물질을 이루고 있다. 실시예 1 내지 4의 경우 비교예와 같이 균일한 입자 형태를 보이지만, 표면에 나노 사이즈의 코팅 물질이 균일하게 균일하게 코팅되었으며, 코팅되는 양이 증가함에 따라 형태(morphology)가 변하는 것을 관찰할 수 있다. In addition, as shown in the scanning electron micrograph of FIG. 2, in the case of the uncoated lithium nickel composite oxide of Comparative Example, the active material has a spherical active material of about 7 μm having uniform primary particles. Examples 1 to 4 show a uniform particle shape as in Comparative Example, but the nano-sized coating material was uniformly coated on the surface, and it can be observed that the morphology changes as the amount of coating increases. have.
<테스트 셀의 제작 ><Production of test cell>
이와 같이 제조된 실시예 1 내지 4 및 비교예의 양극활물질, 결합제로서 폴리비닐리덴플루오라이드(PVDF), 도전재로서 슈퍼 P(Super P)를, 중량비로 96 : 2 : 2으로 용매(N-메틸피롤리돈)와 함께 혼합하여 양극 활물질조성물 슬러리를 제조하고, 이 슬러리를 테이프 형태로 캐스팅하여 극판을 제조하였다. Thus prepared positive electrode active materials of Examples 1 to 4 and Comparative Examples, polyvinylidene fluoride (PVDF) as a binder, Super P (Super P) as a conductive material, solvent (N-methyl in 96: 2: 2 by weight ratio) Pyrrolidone) was mixed together to prepare a positive electrode active material composition slurry, and the slurry was cast in the form of a tape to prepare a plate.
이 극판에 대한 대극으로서 Li-호일을 사용하고, EC/DMC/EMC/FB=3/3/3/1 인 혼합물 및 LiPF6를 포함하는 전해액을 사용하여 코인 셀 타입의 반쪽 전지를 제조하였다. A coin cell type half cell was produced using Li-foil as a counter electrode for this electrode plate and using an electrolyte solution containing LiPF 6 and a mixture of EC / DMC / EMC / FB = 3/3/3/1.
<실험예 - 물성 측정> Experimental Example-Measurement of Physical Properties
상기와 같이 얻어진 셀은 [Li2MnO4/LiPF6 (1 M) in EC+2EMC/Li]로 표시되는데, 이 셀의 율(C-rate) 특성, 수명 특성, 안전성 특성을 평가하였다. The cell obtained as described above is represented by [Li 2 MnO 4 / LiPF 6 (1 M) in EC +2 EMC / Li], and the rate (C-rate), life, and safety characteristics of the cell were evaluated.
1. 율 특성 평가1. Rate Characterization
율(C-rate)특성을 평가하기 위하여 전기화학 분석장치(Toyo사 Toscat3000U, Japan)를 이용하여 상온(30), 3.0~4.3V의 전위영역, 다양한 전류밀도 조건에서 충, 방전 실험을 하여 사이클에 따른 용량 변화를 도 3에 나타내었다. In order to evaluate the C-rate characteristics, a charge and discharge experiment was conducted using an electrochemical analyzer (Toscat 3000U, Japan, Toyo) at room temperature (30), 3.0 to 4.3V potential range, and various current density conditions. The dose change with is shown in FIG.
비교예에 비하여 실시예 1 내지 4의 양극활물질을 적용한 경우 다양한 전류밀도 조건에서 매우 우수한 용량 특성을 나타내는 것으로 확인되었다.When the cathode active materials of Examples 1 to 4 were applied as compared to the comparative examples, it was confirmed that the capacitors exhibited excellent capacity characteristics under various current density conditions.
2. 수명 특성의 평가2. Evaluation of life characteristics
수명 특성의 평가는 3.4 내지 4.3 V 범위의 고온(60) 사이클에 따른 비가역 용량의 변화를 측정하여 도 4에 그 결과를 나타내었다. 도 4에서 보이는 바와 같이, 실시예 1 내지 4가 비교예 1에 비해 전반적으로 사이클 증가에 따라 용량 감소가 거의 없어 고온 사이클 수명 특성이 우수함을 알 수 있다. 이러한 결과는 활물질의 표면에 코팅된 Al2O3, TiO2 등이 전지의 사이클이 진행됨에 따라 전극 표면에서 발생하는 잔류 리튬과 전해액의 부반응을 억제하여 전극의 저항 증가를 최소화시켜 리튬 소모를 막아줌으로써 수명 성능이 좋아지는 것으로 판단된다. The evaluation of the life characteristics is shown in FIG. 4 by measuring the change in irreversible capacity with high temperature 60 cycles in the range of 3.4 to 4.3 V. As shown in FIG. 4, it can be seen that Examples 1 to 4 are excellent in high temperature cycle life characteristics because there is almost no capacity decrease with increasing cycle as compared with Comparative Example 1. These results indicate that Al 2 O 3 and TiO 2 coated on the surface of the active material suppress side reactions of residual lithium and electrolyte generated on the surface of the electrode as the battery cycle progresses, thereby minimizing the increase in resistance of the electrode, thereby preventing lithium consumption. It is thought that the lifespan performance is improved by giving.
3. 안전성 특성의 평가3. Evaluation of safety characteristics
본 발명에 따라 제조된 활물질의 열적안정성을 다음과 같은 방법으로 평가하였다. 비교예 1 및 실시예 1 내지 4에 따라 제조된 코인 전지를 상기 4.5V로 충전한 다음 건조실(dry room)에서 해체하여 극판을 분리하였다. 분리된 극판에서 Al-포일위에 도포되어 있던 활물질만을 약 10mg 정도 채취하여 DSC 분석을 분리된 극판에서 Al-포일 위에 도포되어 있던 활물질만을 약 10mg 정도 채취하여 910 DSC(TA Instrument사 제품)를 이용하여 DSC 분석을 실시하였다. The thermal stability of the active material prepared according to the present invention was evaluated by the following method. Coin cells prepared according to Comparative Example 1 and Examples 1 to 4 were charged to the 4.5V and then disassembled in a dry room to separate the electrode plates. About 10mg of the active material coated on the Al-foil was collected from the separated plate and about 10mg of the active material coated on the Al-foil was collected from the separated electrode plate. DSC analysis was performed.
DSC 분석은 공기 분위기하에서 100~300 ℃사이의 온도 범위에서 3 ℃/min의 승온 속도로 스캐닝하여 실시하였다. DSC 분석 결과는 도 5에 도시하였다.DSC analysis was performed by scanning at an elevated temperature rate of 3 ° C./min in the temperature range between 100 ° C. and 300 ° C. in an air atmosphere. DSC analysis results are shown in FIG. 5.
DSC 분석 결과 나타나는 상기 발열 피크는 이러한 현상은 전지의 안전성을 저하시키는 요인이 된다. 본 발명의 실시예 3에 따라 제조된 활물질의 발열 피크의 면적은 비교예 1보다 훨씬 감소하였다. 이와 같은 발열량의 감소는 이러한 결과는 활물질의 표면에 코팅된 Al2O3, TiO2 등이 전지의 사이클이 진행됨에 따라 전극 표면에서 발생하는 잔류 리튬과 전해액의 부반응을 억제하여 양극 활물질의 열적 안정성이 우수하다는 사실을 보여주는 것이다. The exothermic peak that appears as a result of DSC analysis is such a phenomenon that deteriorates the safety of the battery. The area of the exothermic peak of the active material prepared according to Example 3 of the present invention was much reduced than that of Comparative Example 1. This reduction in heat generation results in the thermal stability of the positive electrode active material by suppressing side reactions of residual lithium and electrolyte generated on the surface of the electrode as Al 2 O 3 , TiO 2, etc. coated on the surface of the active material as the battery cycle progresses. To show that this is excellent.
본 발명은 활물질 표면에 형성된 100 nm 이하 크기의 코팅 원소 함유 화합물은 활물질의 내부저항을 작게 할 수 있어 방전 전위의 저하를 방지하여 전류밀도(C-rate) 변화에 따른 높은 방전 전위 특성을 유지하는 특성을 나타내는 리튬 2차 전지의 양극활물질용 리튬 복합 산화물 및 제조 방법으로 유용하게 이용될 수 있다. According to the present invention, the coating element-containing compound having a size of 100 nm or less formed on the surface of the active material can reduce the internal resistance of the active material, thereby preventing the lowering of the discharge potential, thereby maintaining high discharge potential characteristics according to the current density (C-rate) change. It can be usefully used as a lithium composite oxide for a cathode active material and a manufacturing method of a lithium secondary battery exhibiting characteristics.

Claims (13)

  1. [규칙 제91조에 의한 정정 21.03.2011]
    화학식 1로 표시되는 화합물의 표면에 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자가 건식 코팅법에 의하여 코팅된 리튬 복합 산화물.
    [화학식 1]
    LixNi1-y-zCoyMzO2
    (0.98≤x≤1.1, 0.1≤y≤0.35, 0.03≤z≤0.35, M은 Al, Zn, Ti, V, Cr, Mn, Fe 및 Y로 이루어지는 군으로부터 선택되는 적어도 일종의 금속 원소이다)
    [Revisions under Rule 91 21.03.2011]
    At least one oxide selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 on the surface of the compound represented by Formula 1 Lithium composite oxide in which particles are coated by a dry coating method.
    [Formula 1]
    Li x Ni 1-yz Co y M z O 2
    (0.98≤x≤1.1, 0.1≤y≤0.35, 0.03≤z≤0.35, M is at least one kind of metal element selected from the group consisting of Al, Zn, Ti, V, Cr, Mn, Fe and Y)
  2. 제 1항에 있어서,The method of claim 1,
    상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물은 Al2O3 또는 TiO2 인 것인 리튬 복합 산화물. Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 At least one oxide selected from Al is2O3 Or TiO2Being Lithium composite oxide.
  3. 제1항에 있어서, The method of claim 1,
    상기 리튬 복합 산화물은, 1차 입자로 이루어지고, 1차 입자는 2차 입자를 형성하며, The lithium composite oxide is composed of primary particles, the primary particles to form secondary particles,
    상기 1차 입자의 평균 입자지름은 0.1 ㎛ 이상 3 ㎛ 이하이고, 상기 2차 입자의 평균 입자지름은, 5㎛ 이상 15㎛ 이하인 것을 특징으로 하는 리튬 복합 산화물.The average particle diameter of the said primary particle is 0.1 micrometer or more and 3 micrometer or less, The average particle diameter of the said secondary particle is 5 micrometers or more and 15 micrometers or less, The lithium composite oxide characterized by the above-mentioned.
  4. 제1항에 있어서, The method of claim 1,
    상기 리튬 복합 산화물의 탭밀도는, 2.2g/㎤ 이상, 2.8g/㎤ 이하인 것을 특징으로 하는 리튬 복합 산화물.The tap density of the lithium composite oxide is 2.2 g / cm 3 or more and 2.8 g / cm 3 or less.
  5. 제 1항에 있어서,The method of claim 1,
    상기 M 은 Al 인 것인 리튬 복합 산화물. M is Al is a lithium composite oxide.
  6. 상기 제1항 내지 제 5항의 리튬 복합 산화물로 이루어진 양극 활물질을 포함하는 리튬이온 이차전지. A lithium ion secondary battery comprising a cathode active material made of the lithium composite oxide of claim 1.
  7. i)코발트염, 니켈염, M 염으로서 알루미늄의 혼합수용액에 착제로서 암모니아수와 pH 조절제로서 수산화기를 제공하는 알칼리용액을 첨가하고 공침시킨 후 추출함으로써 1차 입자가 뭉쳐져 2차 입자를 이루고 있는 니켈-코발트-알루미늄 복합수산화물을 형성하는 단계, i) Ni-cobalt, nickel, and M salts are mixed with a solution of aluminum as a complex, ammonia water as a complex, and an alkali solution providing a hydroxyl group as a pH adjuster. Forming a cobalt-aluminum composite hydroxide,
    ii) 상기 니켈-코발트-알루미늄 복합수산화물에 리튬화합물을 첨가하여 600-800 ℃에서 1차 열처리하여 상기 화학식 1로 표시되는 리튬 니켈 복합 산화물을 형성하는 단계,  ii) adding a lithium compound to the nickel-cobalt-aluminum composite hydroxide to form a lithium nickel composite oxide represented by Chemical Formula 1 by first heat treatment at 600-800 ° C.,
    iii) 상기 ii) 단계에서 얻어진 리튬 니켈 복합 산화물과 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자를 혼합하고, 불활성 기체 분위기하에서 300 - 500 ℃에서 2차 열처리하는 단계를 포함하는 리튬 복합 산화물의 제조 방법. iii) at least one selected from lithium nickel composite oxide obtained in step ii) and Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 A method for producing a lithium composite oxide, which comprises mixing one kind of oxide particles and performing a second heat treatment at 300 to 500 ° C. under an inert gas atmosphere.
  8. 제 7항에 있어서, The method of claim 7, wherein
    상기 i)단계에 있어서, 상기 암모니아 수용액의 농도는 코발트염, 니켈염, 알루미늄염의 혼합수용액 농도의 30 내지 60%인 것인 리튬 복합 산화물의 제조 방법. In the step i), the concentration of the aqueous ammonia solution is 30 to 60% of the concentration of the mixed aqueous solution of cobalt salt, nickel salt, aluminum salt.
  9. 제 7항에 있어서, The method of claim 7, wherein
    상기 i)단계에 있어서, 상기 알칼리수용액은 반응기 내의 pH가 9.0 내지 11.5가 되도록 투입하는 것인 리튬 복합 산화물의 제조 방법. In the step i), the alkaline aqueous solution is a method for producing a lithium composite oxide is added so that the pH in the reactor is 9.0 to 11.5.
  10. 제 7항에 있어서, The method of claim 7, wherein
    상기 iii)단계에 있어서, 상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자의 크기는 100 nm 이하인 것인 리튬 복합 산화물의 제조 방법. In step iii), at least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 The size of is 100 nm or less method for producing a lithium composite oxide.
  11. 제 7항에 있어서, The method of claim 7, wherein
    상기 iii)단계에 있어서, 상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자는 Al2O3 또는 TiO2 인 것인 리튬 복합 산화물의 제조 방법. In step iii), at least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 Is Al 2 O 3 or TiO 2 The method for producing a lithium composite oxide.
  12. 제 7항에 있어서, The method of claim 7, wherein
    상기 iii)단계에 있어서, 상기 Al2O3, TiO2, SiO2, SnO2, MgO, Fe2O3, Bi2O3, Sb2O3, ZrO2 로부터 선택되는 적어도 1종류의 산화물 입자는 상기 화학식 1로 표시되는 리튬 함유 복합 산화물 대비 1 내지 3 중량 % 로 혼합되는 것인 리튬 복합 산화물의 제조 방법. In step iii), at least one oxide particle selected from Al 2 O 3 , TiO 2 , SiO 2 , SnO 2 , MgO, Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , ZrO 2 Method for producing a lithium composite oxide is mixed with 1 to 3% by weight relative to the lithium-containing composite oxide represented by the formula (1).
  13. 제 7항에 있어서, The method of claim 7, wherein
    상기 코발트염, 니켈염, 알루미늄염의 혼합수용액의 상기 반응기에서의 체류시간이 12~24 시간인 것인 리튬 복합 산화물의 제조 방법. The residence time of the mixed aqueous solution of the cobalt salt, nickel salt and aluminum salt in the reactor is 12 to 24 hours.
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