WO2017111479A1 - 이차전지용 양극활물질 및 이를 포함하는 이차전지 - Google Patents
이차전지용 양극활물질 및 이를 포함하는 이차전지 Download PDFInfo
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- WO2017111479A1 WO2017111479A1 PCT/KR2016/015056 KR2016015056W WO2017111479A1 WO 2017111479 A1 WO2017111479 A1 WO 2017111479A1 KR 2016015056 W KR2016015056 W KR 2016015056W WO 2017111479 A1 WO2017111479 A1 WO 2017111479A1
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- lithium
- active material
- positive electrode
- secondary battery
- metal
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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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
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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
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- 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 cathode active material for a secondary battery having excellent high temperature stability and a secondary battery including the same.
- lithium secondary batteries having high energy density and voltage, long cycle life, and low self discharge rate have been commercialized and widely used.
- a lithium secondary battery has a problem in that its life is rapidly decreased as charging and discharging are repeated. In particular, this problem is more serious at high temperatures. This is due to the phenomenon that the electrolyte is decomposed or the active material is deteriorated due to moisture or other effects in the battery, and the internal resistance of the battery is increased.
- a method of coating the surface of the positive electrode active material is mainly used.
- the coating layer is formed by the conventional method, cracks are frequently generated as the particles split during charging and discharging.
- the battery swelling phenomenon may be caused by the gas generation in the battery by reacting with the electrolyte injected into the lithium secondary battery.
- the first technical problem to be solved by the present invention is to provide a cathode active material for a secondary battery having excellent high temperature stability and a method of manufacturing the same.
- a second technical problem to be solved by the present invention is to provide a secondary battery positive electrode, a lithium secondary battery, a battery module and a battery pack including the positive electrode active material.
- a core containing lithium cobalt oxide, on the surface of the core Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V Lithium-metal oxide and metal oxide further comprising any one or two or more metals selected from the group consisting of, Cr, Ba, Ca and Nb, wherein the lithium-metal oxide is a lithium cobalt oxide and a metal oxide
- a cathode active material for a secondary battery that is a heat fused material.
- a cathode for a secondary battery a lithium secondary battery, a battery module, and a battery pack including the cathode active material.
- the positive electrode active material for a secondary battery according to the present invention includes a thermally fused material of lithium cobalt oxide and a metal raw material exhibiting high temperature stability on the particle surface side in addition to the surface of the particle, thereby preventing cracks on the surface of the active material during charging and discharging. There is no fear of gas generation, and it is possible to improve the high temperature storage stability and life characteristics when applying the battery.
- Figure 1 is a photograph of the cathode active material prepared in Example 1-1 observed with a transmission electron microscope.
- Figure 2 is a photograph of the cathode active material prepared in Comparative Example 1-1 observed with a transmission electron microscope.
- Example 3 is a result of evaluating the high temperature life characteristics of the lithium secondary battery including the positive electrode active material of Example 1-1 and Comparative Example 1-1, respectively.
- Example 4 is a result of evaluating the high temperature life characteristics of the lithium secondary battery including the positive electrode active material of Example 1-1 and Comparative Example 1-2, respectively.
- Example 5 is a result of evaluating the gas generation amount of the lithium secondary battery including the cathode active material of Example 1-1 and Comparative Example 1-1, respectively.
- Example 6 is a result of evaluating the gas generation amount of the lithium secondary battery including the positive electrode active material of Example 1-1 and Comparative Example 1-2, respectively.
- a cathode active material for a secondary battery according to an embodiment of the present invention
- a core comprising lithium cobalt oxide
- Lithium-metal including any one or two or more metals selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb on the surface of the core Further comprising oxides and metal oxides,
- the lithium-metal oxide is a thermal fusion of the lithium cobalt oxide and the metal oxide.
- the cathode active material according to an embodiment of the present invention has a lithium cobalt oxide having high temperature stability not only on the surface of the core constituting the active material but also on an inner region close to the core surface through a calcination process at a high temperature during manufacture.
- lithium-metal oxide which is a thermal fusion material of metal oxide
- gas generation and core by reaction with electrolyte are prevented by blocking contact between core and electrolyte.
- the positive electrode active material can be prevented from being dissolved in the electrolyte by reaction with the hydrofluoric acid derived from the electrolyte.
- 'fusion' refers to a physical or chemical bond between lithium cobalt oxide and a metal oxide at an interface thereof, wherein an element constituting the lithium cobalt oxide and a metal oxide is formed at an interface between the lithium cobalt oxide and a metal oxide. It is coexisting.
- the core includes lithium cobalt oxide.
- Lithium cobalt oxide has a somewhat low structural stability, but has excellent life characteristics and charge and discharge efficiency.
- the lithium cobalt oxide may have a layered structure.
- the layered crystal structure facilitates the insertion and desorption of lithium during charge and discharge, thereby further improving the capacity characteristics of the battery.
- the lithium cobalt oxide may be doped with any one or two or more doping elements selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb. .
- doping elements selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb.
- the lithium cobalt oxide may be to include a compound of formula (1):
- M 1 is any one or two or more doping elements selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb, a and b is the atomic fraction of the independent oxide composition elements, respectively -0.05 ⁇ a ⁇ 0.05 and 0 ⁇ b ⁇ 0.02.
- the lithium cobalt oxide may be lithium rich lithium cobalt oxide having an atomic ratio of Li / Co in Formula 1 above.
- the structural stability of the active material in particular, the structural stability at high temperature can be improved to prevent capacity deterioration even at high temperatures, and the reactivity with the electrolyte can be reduced to reduce gas generation.
- the surface may have a higher SOC for the mechanically advantageous surface, and conversely, the inside may have a lower SOC.
- the core including the lithium cobalt oxide is not particularly limited in shape, and may have various shapes such as spherical and ellipsoidal.
- the core may further include concavities and convexities on the surface depending on the open pores located on the surface or the manufacturing method during its manufacture.
- the uneven formation on the surface of the core according to the manufacturing process, the positive electrode active material according to an embodiment of the present invention is a lithium cobalt oxide having a fine particle size by mixing and heat treatment particles of lithium cobalt oxide having a different particle size
- the particles may be prepared by fusion of lithium cobalt oxide particles having a large particle size, in which case unevenness may be formed on the surface when the lithium cobalt oxide particles having a fine particle size are partially fused.
- the specific surface area of the core can be increased.
- the irregularities include recesses and iron portions, and the recesses may be partially or entirely embedded with the above-described lithium-metal oxide and metal oxide.
- the cathode active material for a lithium secondary battery according to an embodiment of the present invention including the core as described above includes lithium-metal oxide and metal oxide having high temperature stability on the surface and surface side of the core.
- the cathode active material is manufactured by mixing the raw material of the lithium cobalt oxide and the metal material for forming a lithium composite metal oxide having high temperature stability and then thermally fusion through heat treatment at high temperature, wherein the metal oxide used as the metal raw material and Reaction with lithium on the surface of the lithium cobalt oxide particles forms a thermal fusion in the form of an oxide containing lithium-metal and oxides of the metal.
- the lithium-metal oxide and the metal oxide to be formed commonly include a metal included in the raw material.
- the lithium-metal oxide is specifically any one or two or more metal elements (M) selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb and It may be to include Li.
- the metal element (M) reacts with lithium to form a lithium-metal oxide having excellent thermal stability, and as a result, there is no fear of cracking on the surface of the active material particles during charging and discharging. More specifically, the metal element (M) may include any one or two or more selected from the group consisting of Al, Mg, and Ti, even more specifically may be Al.
- the lithium-metal oxide may include a compound of Formula 2 below:
- M 2 is any one or two or more elements selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb, 2 ⁇ m ⁇ 10, and n is the oxidation number of M.
- composition of the lithium metal oxide of Formula 2 is an average composition of the entire lithium metal oxide formed in the active material.
- the metal oxide includes any one or two or more metal elements (M) selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb. .
- M metal elements
- the lithium-metal oxide of Formula 2 may be LiAlO 2 , LiAlO 4, or the like, and may include any one or a mixture of two. have.
- the metal oxide may be Al 2 O 3 or the like.
- the lithium-metal oxide of Chemical Formula 2 may be Li 2 WO 4 , Li 4 WO 5, or Li 6 WO 6 , and any one of them. Or mixtures of two or more.
- the metal oxide may be W 2 O 3 .
- the lithium-metal oxide of Formula 2 is LiBO 2 .
- Li 2 B 4 O 7 and the like and may include any one or a mixture of the two.
- the metal oxide may be B 2 O 3 or the like.
- the content of the metal element (M) excluding lithium included in the lithium-metal oxide and the metal oxide may be 100ppm to 20,000ppm with respect to the total weight of the positive electrode active material. If the content of M is less than 100ppm, the improvement effect of including the lithium-metal oxide is insignificant, and if it exceeds 20,000ppm, there is a concern that the battery characteristics are rather deteriorated due to excess M.
- the lithium-metal oxides described above may be formed on the core surface along the surface of the core and on the surface side of the inner region of the core.
- the 'surface side' of the core means a surface and an area close to the surface except the center of the core. Specifically, the distance from the surface of the core to the center, i.e. from 0% to less than 100%, more specifically from 0 to 50%, even more specifically from 0% to 20%, relative to the semi-diameter of the core. It means the area corresponding to.
- the thermal fusion of lithium cobalt oxide and metal oxide is positioned on the surface and the surface side of the core, thereby enhancing the surface of the active material and further improving battery performance.
- the lithium composite metal oxide when the lithium composite metal oxide is formed on the core surface, the lithium composite metal oxide may be formed to an appropriate thickness in consideration of the particle diameter of the core for determining the capacity of the positive electrode active material.
- the lithium composite metal oxide layer may be formed in an average thickness ratio of 0.01 to 0.1 with respect to the radius of the core. If the thickness ratio of the surface treatment layer is less than 0.01, the improvement effect due to the formation of the surface treatment layer may be insignificant. If the thickness ratio exceeds 0.1, the resistance to lithium ions passing through the surface treatment layer may increase.
- the particle diameter of the core and the thickness of the surface treatment layer can be measured through particle cross-sectional analysis using a focused ion beam (fib).
- the cathode active material according to an embodiment of the present invention having the structure and configuration as described above has an average particle diameter (D 50 ) of 2 ⁇ m to 20 ⁇ m, and a BET specific surface area of 0.5 m 2 / g to 1.9 m 2. / g.
- the average particle diameter (D 50 ) of the positive electrode active material is less than 2 ⁇ m or the BET specific surface area is more than 1.9 m 2 / g, there is a concern that the dispersibility of the positive electrode active material in the active material layer and the resistance in the electrode are increased due to the aggregation between the positive electrode active materials.
- the average particle diameter (D 50 ) is greater than 20 ⁇ m or the BET specific surface area is less than 0.5 m 2 / g, there is a fear that the dispersibility and capacity of the cathode active material itself decrease.
- the positive electrode active material according to an embodiment of the present invention may exhibit excellent capacity and charge and discharge characteristics by simultaneously promoting the above average particle diameter and BET specific surface area conditions. More specifically, the positive electrode active material may have an average particle diameter (D 50 ) of 3 ⁇ m to 15 ⁇ m and BET specific surface area of 1.0m 2 / g to 1.5m 2 / g.
- the average particle diameter (D 50 ) of the positive electrode active material may be defined as the particle size at 50% of the particle size distribution.
- the average particle diameter (D 50 ) of the core is, for example, electron microscope observation using a scanning electron microscopy (SEM) or a field emission scanning electron microscopy (FE-SEM) or the like. Alternatively, it can be measured using a laser diffraction method. In the measurement by the laser diffraction method, more specifically, after dispersing the positive electrode active material in the dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (for example, Microtrac MT 3000) to give an ultrasonic wave of about 28 kHz to an output of 60 W. After irradiation, the average particle diameter (D 50 ) in the 50% reference of the particle size distribution in the measuring device can be calculated.
- the specific surface area of the positive electrode active material is measured by the Brunauer-Emmett-Teller (BET) method, specifically, under the liquid nitrogen temperature (77K) using BELSORP-mino II manufactured by BEL Japan. It can calculate from nitrogen gas adsorption amount.
- BET Brunauer-Emmett-Teller
- the positive electrode active material according to an embodiment of the present invention may have a tap density of 1.7 g / cc or more, or 1.7 g / cc to 2.5 g / cc.
- the tap density of the positive electrode active material can be measured using a conventional tap density measuring device, and specifically, can be measured using a powder tester manufactured by Seishin.
- the cathode active material according to an embodiment of the present invention may be manufactured by various methods.
- the cathode active material is a surface treatment of the particles of lithium cobalt oxide with a metal-containing raw material, and then sequentially performing the first heat treatment at 200 °C to 500 °C and the second heat treatment at 600 °C to 1200 °C It may be prepared by a manufacturing method comprising a.
- the metal-containing raw material is melted and then reacted with lithium present on the core surface and the surface side of the lithium cobalt oxide to form lithium-metal oxide and metal oxide as a thermally fused material. Done.
- the core of the lithium cobalt oxide is the same as described above.
- the metal-containing raw material may be any one or two or more metal elements (M) selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca and Nb. Metal oxides containing can be used.
- the cathode active material is lithium cobalt oxide particles having different particle sizes, specifically, first lithium cobalt oxide particles having an average particle size (D 50 ) of 2 ⁇ m or less, and an average particle size of 6 ⁇ m or more.
- first lithium cobalt oxide particles having an average particle size (D 50 ) of 2 ⁇ m or less, and an average particle size of 6 ⁇ m or more After mixing the second lithium cobalt oxide particles having a (D 50 ), it may be prepared by a manufacturing method comprising the step of heat treatment at a temperature of 600 °C or more.
- the first lithium cobalt oxide particles, or both the first lithium cobalt oxide and the second cobalt oxide particles may be surface-treated with a metal-containing raw material.
- lithium cobalt oxide particles having different particle sizes When heat-treated at the above-described temperature range using lithium cobalt oxide particles having different particle sizes as described above, lithium cobalt oxide particles having a smaller particle size, that is, first lithium cobalt oxide particles are partially or completely melted. The second lithium cobalt oxide particles are fused. At this time, the surface treatment material in the surface-treated lithium cobalt oxide particles are moved to the surface and inside of the alleles to provide a surface treatment effect.
- the first lithium cobalt oxide particles may have an average particle size (D 50 ) of 200 nm to 500 nm
- the second lithium cobalt oxide particles may have an average particle size (D 50 ) of 6 ⁇ m to 20 ⁇ m. have.
- the surface treatment process for the first lithium cobalt oxide particles, or the first and second lithium cobalt oxide particles may be performed according to a conventional method, specifically, after surface treatment with a metal-containing raw material, 200
- the first heat treatment at 500 ° C to 500 ° C and the second heat treatment at 600 ° C to 1200 ° C may be performed in the same manner as described above.
- the heat treatment may be performed at 600 ° C. or higher, and below 600 ° C., fusion of the first lithium cobalt oxide and thus lithium-metal oxide formation on the core surface may not be easy. More specifically, the heat treatment may be performed at 600 °C to 900 °C.
- According to another embodiment of the present invention provides a cathode and a lithium secondary battery comprising the cathode active material.
- the positive electrode is formed on the positive electrode current collector and the positive electrode current collector, and includes a positive electrode active material layer containing the positive electrode active material.
- the positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes in the battery.
- carbon, nickel, titanium on a surface of aluminum or stainless steel Surface treated with silver, silver or the like can be used.
- the positive electrode current collector may have a thickness of typically 3 ⁇ m to 500 ⁇ m, and may form fine irregularities on the surface of the current collector to increase adhesion of the positive electrode active material.
- it can be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
- the cathode active material layer may include a conductive material and a binder together with the cathode active material described above.
- the conductive material is used to impart conductivity to the electrode.
- the conductive material may be used without particular limitation as long as it has electronic conductivity without causing chemical change. Specific examples thereof include graphite such as natural graphite and artificial graphite; Carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, summer black and carbon fiber; Metal powder or metal fibers such as copper, nickel, aluminum, and silver; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Or conductive polymers such as polyphenylene derivatives, and the like, or a mixture of two or more kinds thereof may be used.
- the conductive material may typically be included in an amount of 1 to 30% by weight based on the total weight of the positive electrode active material layer.
- the binder serves to improve adhesion between the cathode active material particles and adhesion between the cathode active material and the current collector.
- specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC).
- the binder may be included in an amount of 1 to 30% by weight based on the total weight of the positive electrode active material layer.
- the positive electrode may be manufactured according to a conventional positive electrode manufacturing method except for using the positive electrode active material described above.
- the positive electrode active material and optionally, a composition for forming a positive electrode active material layer including a binder and a conductive material may be prepared by applying a positive electrode current collector, followed by drying and rolling.
- the type and content of the cathode active material, the binder, and the conductive material are as described above.
- the solvent may be a solvent generally used in the art, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone or acetone. Water, and the like, one of these alone or a mixture of two or more thereof may be used.
- the amount of the solvent is sufficient to dissolve or disperse the positive electrode active material, the conductive material, and the binder in consideration of the coating thickness of the slurry and the production yield, and to have a viscosity that can exhibit excellent thickness uniformity during application for the production of the positive electrode. Do.
- the positive electrode may be prepared by casting the composition for forming the positive electrode active material layer on a separate support, and then laminating the film obtained by peeling from the support onto a positive electrode current collector.
- an electrochemical device including the anode is provided.
- the electrochemical device may be specifically a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.
- the lithium secondary battery specifically includes a positive electrode, a negative electrode positioned to face the positive electrode, a separator and an electrolyte interposed between the positive electrode and the negative electrode, and the positive electrode is as described above.
- the lithium secondary battery may further include a battery container for accommodating the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container.
- the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.
- the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery.
- the negative electrode current collector may be formed on a 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.
- the negative electrode current collector may have a thickness of about 3 to 500 ⁇ m, and like the positive electrode current collector, fine concavities and convexities may be formed on the surface of the current collector to enhance the bonding force of the negative electrode active material.
- it can be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
- the negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.
- the negative electrode active material layer is coated with a negative electrode active material, and optionally a composition for forming a negative electrode including a binder and a conductive material on a negative electrode current collector and dried, or casting the negative electrode forming composition on a separate support It may be produced by laminating a film obtained by peeling from this support onto a negative electrode current collector.
- a compound capable of reversible intercalation and deintercalation of lithium may be used.
- Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fibers, and amorphous carbon;
- Metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys or Al alloys;
- Metal oxides capable of doping and undoping lithium such as SiO x (0 ⁇ x ⁇ 2), SnO 2 , vanadium oxide, lithium vanadium oxide;
- a composite including the metallic compound and the carbonaceous material such as a Si-C composite or a Sn-C composite, and any one or a mixture of two or more thereof may be used.
- a metal lithium thin film may be used as the anode active material.
- the carbon material both low crystalline carbon and high crystalline carbon can be used. Soft crystalline carbon and hard carbon are typical low crystalline carbon, and high crystalline carbon is amorphous, plate, scaly, spherical or fibrous natural graphite or artificial graphite, Kish graphite (Kish) graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch High-temperature calcined carbon such as derived cokes is typical.
- the binder and the conductive material may be the same as described above in the positive electrode.
- the separator is to separate the negative electrode and the positive electrode and to provide a passage for the movement of lithium ions, if it is usually used as a separator in a lithium secondary battery can be used without particular limitation, in particular to the ion movement of the electrolyte It is desirable to have a low resistance against the electrolyte and excellent electrolytic solution-moisture capability.
- a porous polymer film for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer or the like Laminate structures of two or more layers may be used.
- a porous nonwoven fabrics such as nonwoven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers and the like may be used.
- a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may be optionally used as a single layer or a multilayer structure.
- examples of the electrolyte used in the present invention include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, and the like, which can be used in manufacturing a lithium secondary battery. It doesn't happen.
- the electrolyte may include an organic solvent and a lithium salt.
- the organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move.
- the organic solvent may be an ester solvent such as methyl acetate, ethyl acetate, ⁇ -butyrolactone or ⁇ -caprolactone; Ether solvents such as dibutyl ether or tetrahydrofuran; Ketone solvents such as cyclohexanone; Aromatic hydrocarbon solvents such as benzene and fluorobenzene; Dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate, Carbonate solvents such as PC); Alcohol solvents such as ethyl alcohol and isopropyl alcohol; Nitriles such as R-CN (R is a C2 to C20 linear, branched or cyclic hydrocarbon group, which may include a
- carbonate-based solvents are preferable, and cyclic carbonates having high ionic conductivity and high dielectric constant (for example, ethylene carbonate or propylene carbonate) that can improve the charge and discharge performance of a battery, and low viscosity linear carbonate compounds (for example, a mixture of ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate and the like is more preferable.
- the cyclic carbonate and the chain carbonate may be mixed and used in a volume ratio of about 1: 1 to about 1: 9, so that the performance of the electrolyte may be excellent.
- the lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery.
- the lithium salt is LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (C 2 F 5 SO 3 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 .
- LiCl, LiI, or LiB (C 2 O 4 ) 2 and the like can be used.
- the concentration of the lithium salt is preferably used within the range of 0.1 to 2.0M. When the concentration of the lithium salt is included in the above range, since the electrolyte has an appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance, and lithium ions can move effectively.
- the electrolyte includes, for example, haloalkylene carbonate-based compounds such as difluoro ethylene carbonate, pyridine, tri, etc. for the purpose of improving battery life characteristics, reducing battery capacity, and improving discharge capacity of the battery.
- haloalkylene carbonate-based compounds such as difluoro ethylene carbonate, pyridine, tri, etc.
- Ethyl phosphite triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N, N-substituted imida
- One or more additives such as zolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol or aluminum trichloride may be included. In this case, the additive may be included in 0.1 to 5% by weight based on the total weight of the electrolyte.
- the lithium secondary battery including the cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate
- portable devices such as mobile phones, notebook computers, digital cameras, and hybrid electric vehicles ( It is useful for electric vehicle fields such as hybrid electric vehicle (HEV).
- HEV hybrid electric vehicle
- a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.
- the battery module or the battery pack is a power tool (Power Tool); Electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Or it can be used as a power source for any one or more of the system for power storage.
- Power Tool Electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Or it can be used as a power source for any one or more of the system for power storage.
- a cathode active material containing lithium-aluminum oxide and aluminum oxide as a heat sealant on the core surface and the surface side was prepared.
- a surface treated cathode active material was prepared.
- a positive electrode active material was prepared.
- lithium nickel-based composite oxide core as in Comparative Example 1-2, since the lithium-containing impurities remain on the surface of the core in a high content, the lithium-containing impurities and the metal oxide are bonded at the surface of the core to form lithium-titanium oxide and Titanium oxide was formed.
- a lithium secondary battery was manufactured using the cathode active materials prepared in Examples 1-1 and 1-2 and Comparative Examples 1-1 and 1-2, respectively.
- the positive electrode active material, the carbon black conductive material and the PVdF binder prepared in Examples 1-1 and 1-2 and Comparative Examples 1-1 and 1-2, respectively, in a weight ratio in N-methylpyrrolidone solvent.
- a mixture for the formation of a positive electrode (viscosity: 5000 mPa ⁇ s) was prepared by mixing at a ratio of 95: 2.5: 2.5, applied to an aluminum current collector, dried at 130 ° C., and then rolled to prepare a positive electrode.
- a negative electrode active material a natural graphite, a carbon black conductive material, and a PVdF binder are mixed in an N-methylpyrrolidone solvent in a weight ratio of 85: 10: 5 to prepare a composition for forming a negative electrode, which is applied to a copper current collector. To prepare a negative electrode.
- An electrode assembly was manufactured between the positive electrode and the negative electrode prepared as described above through a separator of porous polyethylene, the electrode assembly was placed in a case, and an electrolyte solution was injected into the case to prepare a lithium secondary battery.
- Example 1-1 The cathode active materials prepared in Example 1-1 and Comparative Example 1-1 were observed with a transmission electron microscope (TEM). The results are shown in FIGS. 1 and 2, respectively.
- TEM transmission electron microscope
- FIG. 1 is a photograph of the cathode active material prepared in Example 1-1 using a transmission electron microscope
- FIG. 2 is a transmission electron microscope at the same magnification as that of FIG. 1. The photograph was observed using.
- lithium aluminum oxide was formed only on the surface of the core particles.
- the cathode active material prepared in Example 1-1 not only lithium-aluminum oxide is formed along the surface of the core particle, but it can be seen that lithium aluminum oxide enters the inside of the particle.
- the lithium secondary battery including the cathode active material prepared in Example 1-1 was superior in cycle characteristics at high temperature as compared with Comparative Example 1-1.
- Example 1-1 further improved the high temperature stability by forming lithium-aluminum oxide, which is a heat fusion product of lithium cobalt oxide and Al 2 O 3 , having high temperature stability not only on the surface of the core but also on the inner region of the core.
- Half batteries including the positive electrode active materials in Examples 1-1 and Comparative Examples 1-1 and 1-2 were prepared, respectively, and gas generation amounts of the batteries were measured in the following manner.
- the half-cell (lithium negative electrode) containing the positive electrode active materials in Examples 1-1 and Comparative Example 1-1, respectively, was charged to 4.5V at a constant current of 0.2C, and then stored at 60 ° C. for 4 weeks. The amount of oxygen gas generated from the cell volume change was measured. The results are shown in FIG. 5.
- Example 1-1 the half-cell (lithium negative electrode) each containing the positive electrode active material in Example 1-1 and Comparative Example 1-2 was charged up to 4.5V at a constant current of 0.2C, and then changed from pressure at 90 ° C. for 5 hours. The amount of oxygen gas generated was measured. The results are shown in FIG. 6.
- Example 1-1 gas generation was remarkably reduced by forming lithium cobalt oxide and lithium-aluminum oxide, which is a heat fusion product of Al 2 O 3 , having high temperature stability not only on the surface of the core but also on the internal region of the core.
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Abstract
Description
Claims (14)
- 리튬 코발트 산화물을 포함하는 코어를 포함하고,상기 코어의 표면 상에, Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca 및 Nb로 이루어진 군에서 선택되는 어느 하나 또는 둘 이상의 금속을 포함하는 리튬-금속 산화물 및 금속 산화물을 더 포함하며,상기 리튬-금속 산화물은 상기 리튬 코발트 산화물과 금속 산화물의 열융착물인 것인 이차전지용 양극활물질.
- 제1항에 있어서,상기 양극활물질은 상기 코어 표면에서부터 중심까지의 총 거리에 대해 코어 표면에서부터 0% 이상이고 100% 미만의 거리에 해당하는 영역 내에 리튬-금속 산화물 및 금속 산화물을 더 포함하는 것인 이차전지용 양극활물질.
- 제1항에 있어서,상기 리튬-금속 산화물 및 금속 산화물은 Al, Mg 및 Ti로 이루어진 군에서 선택되는 어느 하나 또는 둘 이상의 금속를 포함하는 것인 이차전지용 양극활물질.
- 제1항에 있어서,상기 리튬-금속 산화물 및 금속 산화물은 Al을 포함하는 것인 이차전지용 양극활물질.
- 제1항에 있어서,상기 코어는 표면에 요철을 포함하는 것인 이차전지용 양극활물질.
- 제5항에 있어서,상기 요철은 요부 및 철부를 포함하고,상기 요부는 리튬-금속 산화물 및 금속 산화물로 부분 또는 전체 매립된 것인 이차전지용 양극활물질.
- 제1항에 있어서,평균 입자 직경(D50)이 2㎛ 내지 20㎛인 것인 이차전지용 양극활물질.
- 리튬 코발트 산화물의 입자를 금속 함유 원료물질로 표면처리한 후, 200℃ 내지 500℃에서의 1차 열처리 및 600℃ 내지 1200℃에서의 2차 열처리를 순차로 수행하는 단계를 포함하거나; 또는 2㎛ 이하의 평균입자크기를 갖는 제1리튬 코발트 산화물 입자와, 6㎛ 이상의 평균입자크기를 갖는 제2리튬 코발트 산화물 입자를 혼합한 후, 600℃ 이상의 온도에서 열처리하는 단계를 포함하며,상기 제1리튬 코발트 산화물 입자; 또는 상기 제1리튬 코발트 산화물 입자와 제2리튬 코발트 산화물 입자 둘 모두는 금속 함유 원료물질로 표면처리된 것이고,상기 금속은 Al, Mg, W, Mo, Zr, Ti, Ta, Fe, V, Cr, Ba, Ca 및 Nb로 이루어진 군에서 선택되는 어느 하나 또는 둘 이상의 원소를 포함하는 것인, 제1항에 따른 이차전지용 양극활물질의 제조방법.
- 제1항 내지 제7항 중 어느 한 항에 따른 양극활물질을 포함하는 이차전지용 양극.
- 제9항에 따른 양극을 포함하는 리튬 이차전지.
- 제10항에 따른 리튬 이차전지를 단위셀로 포함하는 전지모듈.
- 제11항에 따른 전지모듈을 포함하는 전지팩.
- 제12항에 있어서,중대형 디바이스의 전원으로 사용되는 것인 전지팩.
- 제13항에 있어서,상기 중대형 디바이스가 전기자동차, 하이브리드 전기자동차, 플러그-인 하이브리드 전기자동차 및 전력 저장용 시스템으로 이루어진 군에서 선택되는 것인 전지팩.
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US15/547,261 US10693196B2 (en) | 2015-12-23 | 2016-12-21 | Positive electrode active material for secondary battery and secondary battery including the same |
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