KR102117618B1 - Surface-treated cathode active material for a lithium secondary battery, method of preparing for the same, and a lithium secondary battery comprising the same - Google Patents

Abstract

The present invention is to uniformly coat the surface of the lithium transition metal composite oxide particle with aluminum-doped zinc oxide (AZO), thereby suppressing side reactions between the positive electrode active material and the electrolytic solution, preventing structural collapse of the positive electrode active material, and lifetime and storage at high temperatures. Provided is a secondary battery with improved characteristics.

Description

A cathode active material for a surface-treated lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery containing the same {SURFACE-TREATED CATHODE ACTIVE MATERIAL FOR A LITHIUM SECONDARY BATTERY, METHOD OF PREPARING FOR THE SAME, AND A LITHIUM SECONDARY BATTERY COMPRISING THE SAME}

The present invention relates to a positive electrode active material for a lithium secondary battery, and relates to a positive electrode active material coated with the surface of a lithium transition metal composite oxide particle with aluminum-doped zinc oxide (AZO) and a secondary battery comprising the same.

Lithium secondary batteries have been widely used as power sources for portable devices since they appeared in 1991 as small, lightweight, and large-capacity batteries. Recently, with the rapid development of the electronics, telecommunications, and computer industries, camcorders, mobile phones, and notebook PCs have emerged and are making remarkable developments, and the demand for lithium ion secondary batteries as a power source to drive these portable electronic information and communication devices is growing day by day. Is increasing.

In recent years, research into positive electrode active materials used in batteries has been actively conducted as part of improving performance of lithium secondary batteries and increasing safety.

Until recently, lithium-containing cobalt oxide (LiCoO ₂ ) has been mainly used as a positive electrode active material for the lithium secondary battery. In addition, lithium-containing manganese oxides such as LiMnO _{2 in a} layered crystal structure and LiMn ₂ O _{4 in a} spinel crystal structure, and lithium The use of containing nickel oxide (LiNiO ₂ ) is also contemplated.

Among them, LiCoO ₂ has excellent physical properties such as excellent cycle characteristics and is easy to manufacture, but it is currently used a lot, but it is inferior in safety and is used as a power source in fields that require large amounts of batteries, such as electric vehicles, because it uses a lot of expensive cobalt. There are limitations.

In addition, LiNiO ₂ has been attracting attention as a high-capacity material because it is cheaper than cobalt-based oxide and 70% or more of lithium can be reversibly charged and discharged, but there is a problem of poor stability. In particular, deterioration of battery characteristics due to charging and discharging becomes a problem in a nickel high-content (Ni-rich) composition in which the nickel content exceeds 50% among these nickel-based lithium composite oxides. This is known to be caused by the elution of nickel from the positive electrode active material due to the reaction of the positive electrode with the electrolyte, and is known to cause deterioration of the high temperature lifetime characteristics. In addition, in the nickel high-content (Ni-rich) composition, structural stability and chemical stability are inferior, and the thermal stability of the anode, in particular, a decrease in thermal stability at high temperatures is pointed to as a serious problem.

Therefore, in the case of the positive electrode active material having a high nickel content, by solving the deterioration of the battery characteristics due to side reactions due to direct contact between the positive electrode active material and the electrolyte, it is suitable for high capacity and development of a positive electrode active material capable of solving high temperature stability problems. Research is required.

The problem to be solved by the present invention is to uniformly coat the surface of the lithium transition metal composite oxide particle with aluminum-doped zinc oxide (AZO), thereby suppressing side reactions between the positive electrode active material and the electrolytic solution, preventing structural collapse of the positive electrode active material, and high temperature It is to provide a secondary battery with improved lifespan and storage characteristics.

The present invention is to solve the above problems, and includes a lithium transition metal composite oxide particles, and provides a positive electrode active material for a lithium secondary battery coated on the surface of the lithium transition metal composite oxide particles with a conductive oxide.

In addition, the present invention comprises: a) preparing a AZO target by mixing and stirring by adding a zinc precursor and an aluminum precursor to a solvent; And b) provides a method for producing a positive electrode active material for a lithium secondary battery according to the present invention comprising the step of depositing the AZO thin film on the surface of the lithium transition metal composite oxide particles represented by the formula (1).

[Formula 1]

Li _{1 + x} [Ni _a Co _b Mn _c M _d ] O ₂

(M = Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, and one or more metal elements selected from the group consisting of Ti and Zr , 0.1≤x≤0.6, 0.3≤a≤0.7, 0.1≤b≤0.3, 0.1≤c≤0.3, z + a + b + c + d = 1)

In addition, the present invention provides a positive electrode for a lithium secondary battery, a lithium secondary battery, a battery module and a battery pack including the positive electrode active material for a lithium secondary battery according to the present invention.

The present invention is to uniformly coat the surface of the lithium transition metal composite oxide particle with aluminum-doped zinc oxide (AZO), thereby suppressing side reactions between the positive electrode active material and the electrolytic solution, preventing structural collapse of the positive electrode active material, and lifetime and storage at high temperatures. Characteristics can be improved.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention. At this time, the terms or words used in the present specification and claims should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor appropriately defines the concept of terms to describe his or her invention in the best way. Based on the principle that it can be done, it should be interpreted as a meaning and a concept consistent with the technical idea of the present invention.

The present invention provides a positive electrode active material for a lithium secondary battery comprising lithium transition metal composite oxide particles and coating the surface of the lithium transition metal composite oxide particles with a conductive oxide.

According to one embodiment of the invention, the lithium transition metal composite oxide particles may be a positive electrode active material for a lithium secondary battery, characterized in that represented by the following formula (1).

[Formula 1]

Li _{1 + x} [Ni _a Co _b Mn _c M _d ] O ₂

(M = Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, and one or more metal elements selected from the group consisting of Ti and Zr , 0.1≤x≤0.6, 0.3≤a≤0.7, 0.1≤b≤0.3, 0.1≤c≤0.3, z + a + b + c + d = 1)

The lithium transition metal composite oxide particles include nickel (Ni), manganese (Mn), and cobalt (Co) as a nickel-based lithium transition metal oxide, and the content of nickel is 50% or more based on the total transition metal. do.

In the present invention, the lithium transition metal composite oxide particles can exhibit a high capacity because the content of nickel is more than 50% based on the total transition metal (molar basis). The content of nickel in the lithium transition metal composite oxide particles may be 50% or more or 50% to 90%, preferably 55% or more, more preferably 60% or more in a molar ratio based on the entire transition metal. If the content of nickel is less than 50%, it is difficult to expect a high capacity. Conversely, when it exceeds 90%, structural stability and chemical safety are poor, and high-temperature safety may be significantly deteriorated due to high reactivity with the electrolyte, which is not preferable. .

In addition, the lithium transition metal composite oxide particles of the present invention include manganese (Mn) and cobalt (Co) together with nickel as the transition metal, wherein the content of manganese is 10% to 10% based on the total transition metal (molar basis). It may be 30%, preferably 15% to 20%, and the content of cobalt may be 10% to 30%, preferably 15% to 20%, based on the total transition metal.

In addition, a part of the transition metal component in the nickel-based lithium transition metal oxide is Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si , Ti and Zr may be substituted with one or more metal elements (M) selected from the group consisting of. The substituted metal element (M) is preferably Ti, Zr, Mg, Al, etc. from the viewpoint of structural stability.

At this time, the content of the substituted element (M) is preferably 0.01% to 10%, preferably 0.05% to 5%, more preferably 0.1% to 2%, based on the total transition metal (molar basis). Do. If the metal element (M) component is less than 0.1%, the effect of substitution is relatively low, whereas when the amount of the component exceeds 5%, the amount of transition metals such as nickel is relatively reduced, so the battery capacity is reduced. It is not desirable because it may decrease.

The lithium transition metal composite oxide is LiNi _{0 . 5} Co _{0 . 2} Mn _{0 . 3} O ₂ , LiNi _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ , LiNi _0.7 Co _0.15 Mn _0.15 O ₂ , and the like, LiNi _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ is preferred.

As described above, the positive electrode active material for a secondary battery of the present invention is characterized by using a lithium transition metal composite oxide in which nickel is occupied by 50% or more at an octahedral site occupied by a transition metal. Meanwhile, the lithium transition metal composite oxide may have a layered structure (space group R-3m) or a spinel structure (space group Fd-3m).

As described above, the present invention is a positive electrode active material containing a Samsung component, by coating a conductive oxide uniformly dispersed on the surface of a nickel high content (Ni-rich) lithium transition metal oxide particle having a nickel content of 50% or more in the transition metal, By inhibiting direct contact with the positive electrode active material, it is possible to suppress side reactions with the electrolyte to prevent structural collapse of the positive electrode active material, and improve life and storage characteristics at high temperatures.

According to an embodiment of the present invention, the conductive oxide is one or more oxides selected from the group consisting of zinc oxide (ZnO), tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ) and cadmium oxide (CdO). You can.

Among them, zinc oxide (ZnO) has excellent optical and electrical properties due to its characteristics such as resistance to a reducing atmosphere, low price, and non-stoichiometric defect structure, wide band gap energy, and large piezoelectric constant. .

In addition, since it has transparency, it is widely used as a transparent electrode for information display devices. A material having both transparency and electrical characteristics is called transparent conducting oxide (TCO).

Zinc oxide (ZnO) has low resistance (<10 ^-3 Ωcm), low temperature deposition property, low price, non-toxicity, and rich reserves, and is widely used as a transparent conductive oxide, indium tin oxide (ITO). It is attracting attention as a substitute for solving the high price, the toxicity and depletion of indium.

The present invention is characterized in that a group III element doped is used as a conductive oxide to reduce the specific resistance of zinc oxide (ZnO) and improve conductivity as an alternative to solving the above problem. Specifically, the group 3 element is boron (B ), Indium (In), aluminum (Al) or gallium (Ga) may be used, and more specifically, aluminum (Al) may be used.

The present invention, by using aluminum doped zinc oxide (Aluminum-doped Zinc Oxide, AZO) as a conductive oxide coated on the surface of the lithium transition metal composite oxide particles, it is possible to provide a secondary battery with improved battery performance.

Resistivity of pure zinc oxide (ZnO) is increased when the 3 such as Al ^{3 +} addition of ions to a relatively and show high values, zinc oxide (ZnO) of 0.2 Ωcm, free electron density (free electron density) The specific resistance can be lowered to ~ 10 ^-4 Ωcm, the conductivity can be improved, and electrical characteristics can be controlled through this.

Meanwhile, in the present invention, the aluminum doping amount may be 0.01 to 10 wt%, specifically 1 to 3 wt%, based on the total weight of aluminum-doped zinc oxide (AZO). When the amount of aluminum doping is less than 0.01 wt%, the effect of reducing resistivity and improving conductivity may be negligible by doping, whereas when it exceeds 10 wt%, a problem of increasing resistance may occur.

According to an embodiment of the present invention, the content of the conductive oxide may be 0.05 to 5 wt%, specifically 0.05 to 3 wt%, relative to the total weight of the surface-coated lithium transition metal composite oxide. The content of the conductive oxide may be 0.05 wt% or more in terms of thermal stability, and may be 5 wt% or less in terms of output and life characteristics.

Meanwhile, according to an embodiment of the present invention, the conductive oxide coating is characterized by uniformly coating the surface of the lithium transition metal composite oxide particles of the present invention in the form of a thin film, and in the form of nanoparticles. Does not mean

In the present invention, by uniformly coating the conductive oxide, it is possible to prevent ionic conductivity from being deteriorated at high temperatures at which electrode reactions become active. As a result, it is possible to manufacture a positive electrode active material suitable for high output of the battery and high energy density of the battery.

In addition, the coating (deposition) may be made by an ultrasonic spray (Ultra-sonic spray), atomic layer deposition (Atomic layer deposition, ALD), chemical vapor deposition (Chemical vapor deposition, CVD) or sputtering (Sputtering).

Ultra-sonic spray is a method of spraying a precursor solution to generate fine droplets, and then spraying them with a carrier gas to deposit them. The droplets sprayed by the carrier gas increase the concentration of the solute by evaporation of the solvent, and finally precipitation of the solute from the surface occurs. In general, since one particle is produced from one droplet, it is possible to obtain a small spherical particle without aggregation.

Ultra-sonic spray is a simple process, it is possible to process at room temperature and normal pressure, is suitable for large areas, and can produce particles with a relatively uniform size and composition. have.

Atomic layer deposition (ALD) is a deposition method using a nano thin film deposition technique using the phenomenon of a chemically sticking monoatomic layer. Specifically, by alternately adsorbing and displacing molecules on the surface of the particles, ultra-fine layer-by-layer deposition of the atomic layer thickness is possible, and the coating layer thin film can be stacked as thin as possible.

Atomic layer deposition (ALD) is a feature that makes it easy to control the thickness of a thin film because the thickness of the thin film deposited is determined by the number of cycles. In addition, it exhibits excellent properties in terms of thickness uniformity and reproducibility, and has the advantage of lowering the deposition temperature because it uses chemisorption of the reaction raw material.

In addition, chemical vapor deposition (CVD) refers to a deposition method in which particles formed by chemical reaction of a gas are deposited on the surface of a particle to decompose a raw material gas using external energy to form a thin film by a gas phase reaction, and sputtering. Iran, a kind of vacuum deposition method, refers to a method of generating plasma at a relatively low degree of vacuum, accelerating gas such as ionized argon, and colliding with a target to eject a target atom to form a film on a substrate in its vicinity.

According to the present invention, the conductive oxide thin film can be uniformly and smoothly formed to a thickness of 500 nm or less by the coating (deposition) method. Accordingly, it is possible to uniformly coat the surface of the positive electrode active material as well as the electrode surface. do.

According to an embodiment of the present invention, the thickness of the conductive oxide thin film may be 10 to 500 nm, preferably 50 to 500 nm. When the thickness of the conductive oxide thin film is less than 10 nm, there may be a problem in uniformity and surface protection of the positive electrode active material, and when it is more than 500 nm, there may be a problem in an increase in the resistance layer.

According to an embodiment of the present invention, the average particle diameter (D- ₅₀ ) of the conductive oxide may be 5 to 100 nm, preferably 5 to 50 nm. In the present invention, the average particle diameter (D ₅₀ ) can be measured using, for example, a laser diffraction method or a scanning electron microscope (SEM) photograph. The average particle diameter (D ₅₀ ) of the conductive oxide may be defined as a particle diameter at 50% of the particle size distribution.

When the average particle diameter of the conductive oxide is less than 5 nm, it may be difficult to manufacture conductive oxide particles, whereas when it exceeds 100 nm, a problem may occur in which the coating is uneven and acts as a resistor.

In addition, the method of manufacturing a positive electrode active material for a lithium secondary battery according to the present invention comprises: a) adding a zinc precursor and an aluminum precursor to a solvent, mixing and stirring to prepare an AZO target; And b) may include the step of depositing the AZO thin film on the surface of the lithium transition metal composite oxide particles represented by the formula (1).

[Formula 1]

Li _{1 + x} [Ni _a Co _b Mn _c M _d ] O ₂

(M = Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, and one or more metal elements selected from the group consisting of Ti and Zr , 0.1≤x≤0.6, 0.3≤a≤0.7, 0.1≤b≤0.3, 0.1≤c≤0.3, z + a + b + c + d = 1)

The solvent in step a) is preferably a solvent capable of dissolving both a zinc precursor and an aluminum precursor, and specifically, methanol can be used. In addition, Zinc acetylacetonate may be used as the zinc precursor, and aluminum acetylacetonate may be used as the aluminum precursor. Acetic acid may be additionally added to prevent salt formation upon dissolution.

According to an embodiment of the present invention, the AZO thin film deposition in step b) is performed by an ultrasonic-sonic spray, atomic layer deposition (ALD), chemical vapor deposition (CVD) or sputtering method. (Sputtering).

In addition, the present invention provides a positive electrode for a lithium secondary battery including a positive electrode active material for a lithium secondary battery, a binder, a conductive material, an additive and a solvent according to the present invention, and provides a lithium secondary battery including the positive electrode for a lithium secondary battery.

The lithium secondary battery of the present invention can be manufactured according to a conventional method known in the art. For example, a separator may be placed between the positive electrode and the negative electrode, and an electrolyte solution in which a lithium salt is dissolved may be introduced.

Electrodes of lithium secondary batteries can also be produced by conventional methods known in the art. For example, a slurry is prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant in a positive electrode active material or a negative electrode active material, and then applying (coating) it to a current collector of a metal material, compressing it, and drying it to dry the electrode. Can be produced.

Particularly, the positive electrode for a lithium secondary battery according to an embodiment of the present invention uniformly coats the aluminum-doped zinc oxide (AZO) on the surface of the lithium-transition metal composite oxide particles, thereby suppressing side reactions between the positive electrode active material and the electrolyte, thereby preventing the positive electrode active material. The structure collapse can be prevented, and the service life and storage characteristics at high temperatures can be improved.

The positive electrode active material of the present invention is as described above, and the negative electrode active material may be a carbon material, lithium metal, silicon, tin, or the like, which can normally occlude and release lithium ions. Preferably, a carbon material may be used, and both low-crystalline carbon and high-crystalline carbon may be used as the carbon material. Soft carbon and hard carbon are typical examples of low crystalline carbon, and natural graphite, Kish graphite, pyrolytic carbon, and liquid crystal pitch-based carbon fibers include high crystalline carbon. High-temperature calcined carbons such as (mesophase pitch based carbon fiber), carbon microbeads, Mesophase pitches and petroleum or coal tar pitch derived cokes are typical examples.

The current collector of the metal material has high conductivity and is a metal to which the slurry of the electrode active material can be easily adhered, and any one that is not reactive in the voltage range of the battery can be used. Non-limiting examples of the positive electrode current collector include foil made of aluminum, nickel, or a combination thereof, and non-limiting examples of the negative electrode current collector are copper, gold, nickel or copper alloy, or combinations thereof. Foil, etc.

The conductive material is not particularly limited as long as it can be generally used in the art, for example, artificial graphite, natural graphite, carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, carbon fiber, metal fiber , Aluminum, tin, bismuth, silicon, antimony, nickel, copper, titanium, vanadium, chrome, manganese, iron, cobalt, zinc, molybdenum, tungsten, silver, gold, lanthanum, ruthenium, platinum, iridium, titanium oxide, polyaniline, Polythiophene, polyacetylene, polypyrrole, or a combination thereof may be applied, and a carbon black-based conductive material may be commonly used.

The binder is not particularly limited as long as it can be generally used in the art, but in general, polyvinylidene fluoride (PVdF), polyhexafluoropropylene-polyvinylidene fluoride copolymer (PVdF / HFP), poly (Vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly (methyl methacrylate), poly (ethyl acrylate), polytetrafluoroethylene (PTFE), Polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene propylene diene monomer (EPDM), or mixtures thereof may be used.

The electrolyte contained in the lithium secondary battery according to the present invention is propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile , Dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethylcarbonate (EMC), gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate , Ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate and one or more mixed organic solvents selected from the group consisting of butyl propionate.

In addition, the electrolyte according to the present invention may further include a lithium salt, the anion of the lithium salt is F-, Cl-, Br-, I-, NO _3- , N (CN) _2- , BF _4- , ClO _4- , PF _6- , (CF ₃ ) ₂ PF _4- , (CF ₃ ) ₃ PF _3- , (CF ₃ ) ₄ PF _2- , (CF ₃ ) ₅ PF-, (CF ₃ ) ₆ P- , F ₃ SO _3- , CF ₃ CF ₂ SO _3- , (CF ₃ SO ₂ ) ₂ N-, (FSO ₂ ) ₂ N-, CF ₃ CF ₂ (CF ₃ ) ₂ CO-, (CF ₃ SO ₂ ) ₂ CH-, (SF ₅ ) ₃ C-, (CF ₃ SO ₂ ) ₃ C-, CF ₃ (CF ₂ ) ₇ SO _3- , CF ₃ CO _2- , CH ₃ CO _2- , SCN- and ( CF ₃ CF ₂ SO ₂ ) _{2 It} may be one or more selected from the group consisting of N-.

The secondary battery according to the present invention may be a cylindrical, prismatic, or pouch-type secondary battery, but is not limited to this as long as it corresponds to a charging / discharging device.

In addition, the present invention provides a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.

The battery pack includes a power tool; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); Or it can be used as a power supply for one or more medium and large devices selected from the group consisting of power storage systems.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

Manufacturing example  - AZO  Manufacture of

As a solvent, 1.26L of methanol was added with zincacetylacetonate purchased from Aldrich as a zinc precursor and aluminum acetylacetonate purchased from Sigma-Aldrich as an aluminum precursor to a composition ratio of 97.5: 2.5 and stirred. The AZO thin film deposition solution had a total mole number based on 1 L of methanol of 0.06 M. Then, in order to prevent salt formation, acetic acid of Duksan was added to 0.5% of the total solution and stirred to completely dissolve. Finally, AZO having an average particle diameter (D ₅₀ ) of several tens of nm was obtained.

Example

1) Preparation of surface-coated positive electrode active material

Lithium-transition metal composite oxide particles by a sputtering method _{(LiNi 0. 6 Co 0.} 2 Mn 0. 2 O 2) were deposited on AZO thin film surface. Deposition conditions were carried out in a chamber set to 5 x 10 ^-3 Torr by vacuum pumping to 2 x 10 ^-6 Torr at room temperature using 2 wt% AZO and then injecting argon gas.

2) Manufacture of anode for lithium secondary battery

The prepared surface coating the positive electrode active material _{(... LiNi 0 6 Mn} 0 2 Co 0 2 O 2), a binder (KF1100), the conductive material 93 a (Super-C) respectively: 4: solvent weight ratio of 3 (N -methyl-2-pyrrolidone (NMP) to prepare a positive electrode slurry.

The positive electrode slurry was coated on one surface of an aluminum (Al) thin film, which is a positive electrode current collector having a thickness of 20 μm, and dried to prepare a positive electrode, followed by roll press to process the positive electrode.

3) Manufacture of lithium secondary battery

In addition, the negative electrode active material (carbon powder), the binder (SBR), and the conductive material (carbon black) were mixed in a solvent (N-methyl-2-pyrrolidone, NMP) in a weight ratio of 93: 4: 3 in NMP as a solvent, respectively. A slurry was prepared. The negative electrode slurry was coated on a copper (Cu) thin film as a negative electrode current collector having a thickness of 10 µm, dried to prepare a negative electrode, and then roll pressed to process the negative electrode.

The electrolyte is a solvent in which vinylene carbonate is added to a solvent in which a volume ratio of ethylene carbonate (Ethylene Carbonate), diethyl carbonate (Diethyl Carbonate) and dimethyl carbonate (Dimethyl Carbonate) is 1: 1: 2. Mall's LiPF ₆ It was prepared by dissolving.

After manufacturing the battery in the usual manner with the separator and the anode and cathode prepared as described above, the prepared electrolyte was injected to complete the production of a lithium secondary battery.

Comparative example  One

In the preparation of the positive electrode active material of the above example, a lithium secondary battery was manufactured in the same manner as in the example except that a separate thin film coating was not formed.

The above description of the present invention is for illustration only, and those skilled in the art to which the present invention pertains can understand that the present invention can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and not restrictive.

Claims (18)

Lithium transition metal composite oxide particles represented by the formula (1); And
A positive electrode active material for a secondary battery comprising a; conductive oxide coated in a thin film form on the surface of the lithium transition metal composite oxide particles.
[Formula 1]
Li _{1 + x} [Ni _a Co _b Mn _c M _d ] O ₂
(M = Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, and one or more metal elements selected from the group consisting of Ti and Zr , 0.1≤x≤0.6, 0.3≤a≤0.7, 0.1≤b≤0.3, 0.1≤c≤0.3, z + a + b + c + d = 1).
delete According to claim 1,
The conductive oxide is a positive electrode active material for a lithium secondary battery, characterized in that at least one selected from the group consisting of zinc oxide (ZnO), tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ) and cadmium oxide (CdO).
According to claim 3,
The conductive oxide is a positive electrode active material for a lithium secondary battery, characterized in that the Group 3 element is doped.
The method of claim 4,
The group 3 element is a cathode active material for a lithium secondary battery, characterized in that boron (B), indium (In), aluminum (Al) or gallium (Ga).
According to claim 1,
The conductive oxide is a positive electrode active material for a lithium secondary battery, characterized in that the aluminum-doped zinc oxide (Aluminum-doped Zinc Oxide, AZO).
The method of claim 6,
The amount of aluminum doping is a positive electrode active material for a lithium secondary battery, characterized in that 0.01 to 10 wt% based on the total weight of aluminum-doped zinc oxide (AZO).
According to claim 1,
The content of the conductive oxide is a positive electrode active material for a lithium secondary battery, characterized in that 0.05 to 5 wt% of the total weight of the surface-coated lithium transition metal composite oxide.
delete According to claim 1,
The thickness of the conductive oxide thin film is a positive electrode active material for a lithium secondary battery, characterized in that 10 to 500 nm.
According to claim 1,
The average particle diameter (D ₅₀ ) of the conductive oxide is a positive electrode active material for a lithium secondary battery, characterized in that 5 to 100 nm.
a) preparing a AZO target by mixing and stirring by adding a zinc precursor and an aluminum precursor to a solvent; And b) depositing an AZO thin film using the AZO target on the surface of the lithium transition metal composite oxide particle represented by the following Chemical Formula 1, the method for manufacturing the positive electrode active material for a lithium secondary battery according to claim 1.
[Formula 1]
Li _{1 + x} [Ni _a Co _b Mn _c M _d ] O ₂
(M = Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti and Zr. , 0.1≤x≤0.6, 0.3≤a≤0.7, 0.1≤b≤0.3, 0.1≤c≤0.3, z + a + b + c + d = 1)
The method of claim 12,
Deposition of the AZO thin film in the step b) is characterized in that it is made by an ultrasonic spray method (Ultra-sonic spray), atomic layer deposition (Atomic layer deposition, ALD), chemical vapor deposition (Chemical vapor deposition, CVD) or sputtering (Sputtering) Method for producing a positive electrode active material for a lithium secondary battery.
As a positive electrode for a lithium secondary battery comprising a positive electrode active material, a binder, a conductive material, an additive and a solvent,
The positive electrode active material is a positive electrode for a lithium secondary battery comprising the positive electrode active material for a lithium secondary battery according to any one of claims 1, 3 to 8, 10 and 11.
A lithium secondary battery comprising an anode, a cathode, an electrolyte and a separator,
The positive electrode is a lithium secondary battery that is a positive electrode for a lithium secondary battery according to claim 14.
A battery module comprising the lithium secondary battery according to claim 15 as a unit cell.
A battery pack comprising the battery module according to claim 16.
The method of claim 17,
The battery pack is a battery pack that is used as a power tool, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and one or more medium and large device power sources selected from the group consisting of power storage systems.