Positive electrode active material for lithium secondary battery, method for producing the same, and lithium secondary battery including the same

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same. The present invention provides a positive electrode active material for a lithium secondary battery that can suppress side reactions with an electrolyte and exhibit excellent life characteristics and safety, a method for producing the same, and a lithium secondary battery including the same.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0090443, filed July 12, 2023, and Korean Patent Application No. 10-2024-0090713, filed July 9, 2024, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same. [Background technology]

[0003] As demand for various electronic devices increases, the demand for lithium secondary batteries as their energy source is also increasing rapidly. Recently, the use of lithium secondary batteries has become common as a power source for mobility hardware such as electric vehicles (EVs) and hybrid electric vehicles (HEVs). As a result, many attempts have been made to improve the charge / discharge efficiency and life characteristics of lithium secondary batteries.

[0004] Lithium secondary batteries, which use flammable organic dispersion media as electrolytes, are at risk of overheating and fire if a short circuit occurs. For this reason, there is growing interest in all-solid-state batteries, which use solid electrolytes instead of liquid electrolytes.

[0005] All-solid-state batteries use solid electrolytes such as polymer electrolytes, inorganic electrolytes, and organic-inorganic composite electrolytes, and do not contain flammable organic dispersion media, making them relatively safe.

[0006] In all-solid-state batteries, the positive electrode composite layer is mainly composed of a positive electrode active material, a solid electrolyte, and a conductive material. The solid electrolyte can be a sulfide-based solid electrolyte, which has excellent lithium ion conductivity.

[0007] However, when sulfide-based solid electrolytes come into contact with lithium oxide-based positive electrode active materials, which were once widely used, they form new layers, such as a resistance layer due to the diffusion of metal elements and a lithium-deficient layer due to potential differences, which can reduce battery performance.

[0008] In order to solve the above problems, many attempts have been made to improve the performance of the battery by modifying the surface of the positive electrode active material. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention provides a positive electrode active material for a lithium secondary battery that can suppress side reactions with an electrolyte and exhibit excellent life characteristics and safety.

[0010] The present invention provides a method for producing the positive electrode active material for a lithium secondary battery.

[0011] The present invention also provides a lithium secondary battery comprising the positive electrode active material for a lithium secondary battery. [Means for solving the problem]

[0012] According to one embodiment of the invention, a coating layer disposed on the lithium transition metal oxide particles; The coating layer contains lithium (Li), tantalum (Ta), zinc (Zn) and oxygen (O), A positive electrode active material for a lithium secondary battery is provided.

[0013] According to another embodiment of the invention, providing lithium transition metal oxide particles; providing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor; coating the precursor mixture onto the lithium transition metal oxide particles; and heat-treating the lithium transition metal oxide particles coated with the precursor mixture under an oxygen atmosphere. A method for producing a positive electrode active material for a lithium secondary battery is provided.

[0014] According to yet another embodiment of the invention, there is provided a lithium secondary battery including a positive electrode containing the positive electrode active material, a negative electrode, and an electrolyte.

[0015] Hereinafter, a positive electrode active material for a lithium secondary battery according to an embodiment of the present invention, a method for producing the same, and a lithium secondary battery including the same, particularly an all-solid-state lithium secondary battery, will be described in more detail.

[0016] The terms and words used in this specification and claims should not be interpreted in a way that is limited to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the invention, in accordance with the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention.

[0017] Unless otherwise defined herein, all technical and scientific terms have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. The terms used in the description of this invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention.

[0018] As used herein, the singular forms "a," "an," and "the" include the plural forms as well, unless the context clearly dictates to the contrary.

[0019] As used herein, the meaning of "comprising" embodies certain properties, regions, integers, steps, operations, elements and / or components, and does not exclude the presence or addition of other certain properties, regions, integers, steps, operations, elements, components and / or groups.

[0020] Although the present invention can be embodied in various forms through various modifications, specific embodiments are exemplified and described in detail below, but it should be understood that this is not intended to limit the present invention to the specific disclosed embodiments, and that the present invention includes all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0021] In this specification, when the positional relationship between two parts is described using terms such as "above," "at the top," "below," or "to the side," one or more other parts may be located between the two parts, as long as the expressions "directly" or "immediately" are not used.

[0022] In this specification, when a temporal relationship is described using terms such as "after," "following," "next to," or "before," the terms "directly" or "immediately" are not used, and therefore non-consecutive cases may also be included.

[0023] As used herein, the term "at least one" should be understood to include all possible combinations of one or more of the associated items.

[0024] According to one embodiment of the invention, a coating layer disposed on the lithium transition metal oxide particles; The coating layer contains lithium (Li), tantalum (Ta), zinc (Zn) and oxygen (O), A positive electrode active material for a lithium secondary battery is provided.

[0025] As a result of the inventors' continuous research, it was confirmed that a cathode active material in which a Li-Zn-Ta-O coating layer is formed on lithium transition metal oxide particles can exhibit excellent life characteristics and safety by suppressing side reactions with the electrolyte.

[0026] The Li-Zn-Ta-O coating layer is a buffer layer positioned to minimize direct contact between the lithium transition metal oxide particles and the electrolyte. The Li-Zn-Ta-O coating layer can suppress the formation of a resistance layer due to contact between the lithium transition metal oxide particles and the electrolyte and can mitigate irreversible phase transition of the lithium transition metal oxide particles. As a result, the positive electrode active material for lithium secondary batteries exhibits superior life characteristics and safety compared to those without the coating layer, enabling the provision of lithium secondary batteries with excellent cycle and rate characteristics.

[0027] Furthermore, a portion of the material in the coating layer is doped onto the surface of the lithium transition metal oxide particles in the positive electrode active material, thereby improving the structural stability of the positive electrode active material.

[0028] The positive electrode active material for a lithium secondary battery contains the lithium transition metal oxide particles.

[0029] The lithium transition metal oxide particles can be any material capable of reversibly inserting and extracting lithium ions without any particular limitations. The lithium transition metal oxide particles can include conventionally known oxides containing lithium, a transition metal, and oxygen. The lithium transition metal oxide particles include a compound that exhibits a higher charge / discharge potential than a material used as a negative electrode active material.

[0030] For example, the lithium transition metal oxide particles may be Li a A 1-b R b D2(0.90≦a≦1.8, 0≦b≦0.5);Li a E 1-b R b O 2-c D c (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05);LiE 2-b R b O 4-c D c (0≦b≦0.5, 0≦c≦0.05);Li a Ni1-b-c Co b R c D d (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d≦2);Li a Ni 1-b-c Co b R c O 2-d Z d (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d<2);Li a Ni 1-b-c Co b R c O 2-d Z2(0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d<2);Li a Ni 1-b-c Mr b R c D d (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d≦2);Li a Ni 1-b-c Mr b R c O 2-d Z d (0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d<2);Li a Ni 1-b-c Mr b R c O 2-d Z2(0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d<2);Li a Ni b HAVE BEEN c G d O2(0.90≦a≦1.8、0≦b≦0.9、0≦c≦0.5、0.001≦d≦0.1);Li a Ni b Co c Mr d G e O2(0.90≦a≦1.8、0≦b≦0.9、0≦c≦0.5、0≦d≦0.5、0.001≦e≦0.1);Li a NiG b O2(0.90≦a≦1.8、0.001≦b≦0.1);Li a CoG bO2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a MnG b O2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn2G b O4(0.90≦a≦1.8, 0.001≦b≦0.1);QO2;QS2;LiQS2;V2O5;LiV2O5;LiTO2;LiNiVO4;Li (3-f) J2(PO4)3(0≦f≦2);Li (3-f) It may contain one or more compounds selected from the group consisting of Fe2(PO4)3 (0≦f≦2); and LiFePO4.

[0031] In the exemplified compounds, A is Ni, Co, Mn, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; Z is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; T is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0032] The lithium transition metal oxide particles may be primary particles or secondary particles formed by agglomeration of a plurality of primary particles.

[0033] The lithium transition metal oxide particles may have a particle size of 2 μm to 50 μm, alternatively 2 μm to 25 μm, alternatively 4 μm to 25 μm, alternatively 4 μm to 20 μm, or alternatively 4 μm to 15 μm.

[0034] If the particle size of the lithium transition metal oxide particles is too small, it may be difficult to control the particle size, which may cause difficulties in the manufacturing process. On the other hand, if the particle size of the lithium transition metal oxide particles is too large, losses may occur in terms of rolling density, capacity, etc. Therefore, it is preferable that the lithium transition metal oxide particles have a particle size within the above range.

[0035] The particle size of the lithium transition metal oxide particles can be confirmed through a scanning electron microscope (SEM) image or a transmission electron microscope (TEM) image taken of the particles.

[0036] As shown in FIG. 1, the positive electrode active material for a lithium secondary battery includes a coating layer containing lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O) (hereinafter referred to as a Li-Zn-Ta-O coating layer) located on the lithium transition metal oxide particles.

[0037] There have been many attempts to improve battery performance by modifying the surface of the cathode active material. For example, phosphate-based coating layers have been used, but these still have issues with low ionic conductivity and structural collapse due to volume changes in the Ni-rich cathode active material. This has led to the need for oxide-based coatings that are effective even with low-temperature heat treatment.

[0038] Meanwhile, tantalum (Ta) has a large difference in bonding energy with oxygen, and is a material that can suppress the formation of NiO by doping it on the surface of a positive electrode active material. After researching oxide-based coatings containing tantalum (Ta), the inventors discovered that when a coating layer containing lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O) is applied to lithium transition metal oxide particles, the coating layer acts as a protective layer at the interface between the positive electrode active material and the electrolyte, and at the same time, some of the coating material diffuses to the surface of the lithium transition metal oxide particles in the positive electrode active material, improving structural stability. This finding led to the completion of the present invention.

[0039] The coating layer contains lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O). Tantalum (Ta) preserves the coating layer and prevents direct contact with reactive materials, while zinc (Zn) diffuses to the surface of lithium transition metal oxide particles in the positive electrode active material, preventing the migration of nickel (Ni) within the particles and helping to stabilize the structure of the positive electrode active material, resulting in better life characteristics and safety.

[0040] According to one embodiment, the coating layer may have tantalum (Ta) and zinc (Zn) elements uniformly distributed within the coating layer.

[0041] According to one embodiment, even if the Li-Zn-Ta-O coating layer is formed on the lithium transition metal oxide particles, the layered structure inside the positive electrode active material for lithium secondary batteries can be maintained.

[0042] According to one embodiment, the molar ratio of lithium (Li):tantalum (Ta):zinc (Zn) in the coating layer may be 3:1:1.

[0043] According to one embodiment, the coating layer may include zinc oxide particles.

[0044] According to one embodiment, the coating layer may include lithium tantalum oxide particles.

[0045] According to one embodiment, the coating layer may include at least one of LiTaO3 and Li3TaO4.

[0046] According to one embodiment, the coating layer may include ZnO particles.

[0047] According to one embodiment, the ZnO particles may have a hexagonal crystal structure.

[0048] According to one embodiment, the coating layer may include Li3TaO4 particles.

[0049] According to one embodiment, the Li3TaO4 particles may have a monoclinic crystal structure.

[0050] According to one embodiment, at least a portion of the zinc oxide particles and lithium tantalum oxide particles in the coating layer may have a composite form of ZnO-LiTaO.

[0051] According to one embodiment, the coating layer may comprise the complex compounds ZnO-Li3TaO4 and / or Li2O-ZnO-LiTaO3.

[0052] Meanwhile, a portion of the coating layer is doped onto the surface of the lithium transition metal oxide particles in the positive electrode active material, thereby improving the structural stability of the positive electrode active material.

[0053] For example, as shown in FIG. 1, zinc (Zn) can partially diffuse into the surface of lithium transition metal oxide particles in the positive electrode active material, thereby providing a surface doping effect. At this time, the zinc diffusing into the surface of the lithium transition metal oxide particles is a zinc ion (Zn 2+ ) form may also be used.

[0054] According to an embodiment, the positive electrode active material for a lithium secondary battery may include zinc (Zn) diffused from the coating layer in a region from the surface of a lithium transition metal oxide particle to a depth of 15 nm.

[0055] According to an embodiment, the positive electrode active material for a lithium secondary battery may include zinc (Zn) diffused from the coating layer in a region from the surface of the lithium transition metal oxide particle to a depth of 25 nm.

[0056] According to an embodiment, the positive electrode active material for a lithium secondary battery may include zinc (Zn) diffused from the coating layer in a region from the surface of the lithium transition metal oxide particle to a depth of 30 nm.

[0057] According to one embodiment, the positive electrode active material for a lithium secondary battery may include tantalum (Ta) diffused from the coating layer in a region from the surface of the lithium transition metal oxide particle to a depth of 15 nm.

[0058] According to one embodiment, the positive electrode active material for a lithium secondary battery may include tantalum (Ta) diffused from the coating layer in a region from the surface of the lithium transition metal oxide particle to a depth of 25 nm.

[0059] According to one embodiment, the positive electrode active material for a lithium secondary battery may include tantalum (Ta) diffused from the coating layer in a region from the surface of the lithium transition metal oxide particle to a depth of 30 nm.

[0060] According to one embodiment, when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a depth of 15 nm from the surface of the lithium transition metal oxide particles is taken as 100%, the content of zinc (Zn) present at a depth of 15 nm may be 0.4% or more, or 0.5% or more, or 0.6% or more, and may be less than 1%, 0.9% or less, or 0.8% or less.

[0061] According to one embodiment, when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a depth of 15 nm from the surface of the lithium transition metal oxide particles is taken as 100%, the content of tantalum (Zn) present at a depth of 15 nm may be 0.1% or more, or 0.2% or more, or 0.3% or more, and 0.8% or less, or 0.7% or less, or 0.6% or less.

[0062] According to one embodiment, when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a depth of 25 nm from the surface of the lithium transition metal oxide particles is taken as 100%, the content of zinc (Zn) present at a depth of 25 nm may be 0.3% or more, or 0.4% or more, or 0.5% or more, and 0.9% or less, or 0.8% or less, or 0.7% or less.

[0063] According to one embodiment, when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a depth of 25 nm from the surface of the lithium transition metal oxide particles is taken as 100%, the content of tantalum (Zn) present at a depth of 25 nm may be 0.01% or more, or 0.05% or more, or 0.1% or more, and may be 0.5% or less, or 0.4% or less, or 0.3% or less.

[0064] According to one embodiment, the coating layer may be positioned over 60% or more, 70% or more, 80% or more, 90% or more, or the entire surface area of ​​the lithium transition metal oxide particles. The upper limit of the coating area of ​​the coating layer is not particularly limited, and may be, for example, 100% or less, 99% or less, 98% or less, 97% or less, 96% or less, 95% or less, 94% or less, 93% or less, 92% or less, 91% or less, or 90% or less. However, to fully achieve the above-described effects of the coating layer, it is preferable that the coating layer be positioned over the entire surface area of ​​the lithium transition metal oxide particles.

[0065] If 40% or more of the surfaces of the lithium transition metal oxide particles are free of the coating layer, the lithium transition metal oxide particles may react with the electrolyte at those points, resulting in the formation of high-resistance regions.

[0066] According to an embodiment, the coating layer may be included in an amount of 0.1 to 10 parts by weight, 0.5 to 10 parts by weight, or 1.0 to 10 parts by weight based on 100 parts by weight of the positive electrode active material for a lithium secondary battery.

[0067] To fully achieve the above-described effects of the coating layer, the coating layer is preferably included in an amount of 0.1 parts by weight or more, 0.5 parts by weight or more, or 1.0 parts by weight or more, based on 100 parts by weight of the positive electrode active material for a lithium secondary battery. However, if the content of the coating layer is too high, the performance of the positive electrode active material provided by the lithium transition metal oxide particles may be reduced. Therefore, the coating layer is preferably included in an amount of 10 parts by weight or less, based on 100 parts by weight of the positive electrode active material for a lithium secondary battery.

[0068] The coating layer can be formed to a thickness that can stably suppress the reaction between the lithium transition metal oxide particles and the electrolyte while ensuring lithium ion conductivity.

[0069] According to an embodiment, the coating layer may have a thickness of 1 nm to 200 nm, alternatively 1 nm to 150 nm, alternatively 1 nm to 100 nm.

[0070] If the coating layer is too thin, the stability of the coating layer may be poor. Furthermore, if the coating layer is too thin, uncoated areas may occur on the surface of the lithium transition metal oxide particles, and high-resistance areas may form at those areas due to the reaction between the lithium transition metal oxide particles and the electrolyte. However, if the coating layer is too thick, lithium ion conductivity may decrease.

[0071] The thickness of the coating layer can be calculated by comparing the particle size of the lithium transition metal oxide particles with that of the positive electrode active material for a lithium secondary battery, or can be determined by observing a cross section of the positive electrode active material using a transmission electron microscope (TEM).

[0072] According to one embodiment, the lithium secondary battery may be an all-solid-state battery.

[0073] According to one embodiment, the all-solid-state battery may be a sulfide-based all-solid-state battery.

[0074] According to another embodiment of the invention, providing lithium transition metal oxide particles; providing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor; coating the precursor mixture onto the lithium transition metal oxide particles; and heat-treating the lithium transition metal oxide particles coated with the precursor mixture under an oxygen atmosphere. A method for producing a positive electrode active material for a lithium secondary battery is provided.

[0075] First, a step of preparing lithium transition metal oxide particles is performed.

[0076] The lithium transition metal oxide particles may be prepared from a conventional oxide containing lithium, a transition metal, and oxygen, and the lithium transition metal oxide particles may be substituted for the above-described content.

[0077] A step of providing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor is performed.

[0078] The precursor mixture can be prepared in the form of a solution by stirring the lithium precursor, the tantalum precursor, and the zinc precursor in a suitable solvent such as an alcohol.

[0079] As the lithium precursor, oxides containing lithium such as Li2O, CH3OLi, and CH3CH2OLi can be used without any particular limitation.

[0080] As the tantalum precursor, oxides containing tantalum such as (CH3O)5Ta and (CH3CH2O)5Ta can be used without any particular limitation.

[0081] As the zinc precursor, oxides, ammonium salts, acetates, etc. containing zinc can be used without any particular limitation.

[0082] According to one embodiment, the precursor mixture may include lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O) precursors to meet a desired composition.

[0083] Preferably, the precursor mixture may contain the precursors in a molar ratio of lithium (Li):tantalum (Ta):zinc (Zn) of 3:1:1.

[0084] A step of coating the precursor mixture onto the lithium transition metal oxide particles is performed.

[0085] According to an embodiment, the coating step may be performed by adding the lithium transition metal oxide particles to the precursor mixture in a solution state, stirring the mixture, and drying the mixture to remove the solvent contained in the precursor mixture.

[0086] In the coating step, the content, thickness, area ratio, etc. of the coating layer applied to the positive electrode active material can be controlled by adjusting the composition and solid content, etc. of the precursor mixture.

[0087] The lithium transition metal oxide particles coated with the precursor mixture are then heat-treated in an oxygen atmosphere.

[0088] According to one embodiment, the heat treatment may be performed at a temperature of 300°C or higher, alternatively 300°C to 1000°C, alternatively 350°C to 1000°C, alternatively 350°C to 900°C, alternatively 400°C to 800°C.

[0089] If the heat treatment temperature is too low, the adhesion and density of the Li-Zn-Ta-O coating layer formed by the heat treatment may decrease, and the contact efficiency of the Li-Zn-Ta-O coating layer may decrease. However, if the heat treatment temperature is too high, material deformation of the lithium transition metal oxide particles or the coating layer may occur. Therefore, it is preferable that the heat treatment be performed within the above temperature range.

[0090] The heat treatment may be performed at the heat treatment temperature for 0.5 to 12 hours, and the heat treatment time can be adjusted taking into account the time required for the Li—Zn—Ta—O coating layer to stabilize.

[0091] By carrying out the above steps, a positive electrode active material for a lithium secondary battery can be prepared, which includes the lithium transition metal oxide particles and the coating layer located on the lithium transition metal oxide particles.

[0092] The positive electrode active material for a lithium secondary battery prepared by the method includes lithium transition metal oxide particles and a coating layer disposed on the lithium transition metal oxide particles, and the coating layer may include zinc oxide particles and lithium tantalum oxide particles.

[0093] The coating layer can include at least one of LiTaO3 and Li3TaO4.

[0094] The coating layer may include ZnO particles.

[0095] The ZnO particles may have a hexagonal crystal structure.

[0096] The coating layer can include Li3TaO4 particles.

[0097] The Li3TaO4 particles may have a monoclinic crystal structure.

[0098] At least a portion of the zinc oxide particles and lithium tantalum oxide particles in the coating layer may have a composite morphology of ZnO-LiTaO.

[0099] The coating layer may comprise the complex compounds ZnO-Li3TaO4 and / or Li2O-ZnO-LiTaO3.

[0100] The coating layer has been described above.

[0101] According to yet another embodiment of the invention, there is provided a lithium secondary battery comprising a positive electrode containing the above-described positive electrode active material, a negative electrode, and an electrolyte.

[0102] The lithium secondary battery includes a positive electrode containing the positive electrode active material, thereby exhibiting excellent cycle characteristics and rate characteristics as well as excellent life characteristics and safety.

[0103] As a result, the lithium secondary battery can be used as an energy source with improved performance and safety in the fields of portable electronic devices such as mobile phones, laptops, tablet computers, mobile batteries, and digital cameras; and in the field of transportation means such as electric cars, electric motorcycles, and personal mobility devices.

[0104] The positive electrode can be prepared using a mixture of the positive electrode active material, a conductive material, and an electrolyte.

[0105] According to an embodiment, the positive electrode active material may be included in an amount of 70 wt % to 95 wt % of the total weight of the positive electrode material.

[0106] Specifically, the content of the positive electrode active material may be 70 wt% or more, alternatively 80 wt% or more, or alternatively 85 wt% or more, and 95 wt% or less, alternatively 93 wt% or less, or alternatively 90 wt% or less, based on the total weight of the positive electrode material. Preferably, the content of the positive electrode active material may be 70 wt% to 95 wt%, alternatively 80 wt% to 95 wt%, alternatively 85 wt% to 93 wt%, or alternatively 85 wt% to 90 wt%, based on the total weight of the positive electrode material.

[0107] The conductive material is used to impart electrical conductivity to the electrode.

[0108] The conductive material can be any material that has electronic conductivity without causing chemical changes in the battery. Non-limiting examples of the conductive material include carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; graphite, such as natural graphite and artificial graphite; metal powder or metal fiber, such as copper, nickel, aluminum, and silver; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives. The conductive material can be one or a mixture of two or more of the above-mentioned materials.

[0109] The content of the conductive material can be adjusted within a range that provides an appropriate level of conductivity without causing a decrease in battery capacity, and is preferably 1 wt % to 10 wt % or 1 wt % to 5 wt % based on the total weight of the cathode material.

[0110] Any electrolyte known in the art to which the present invention pertains that is applicable to lithium secondary batteries may be used without any particular limitation, for example, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc.

[0111] As an example, the electrolyte may be a solid inorganic electrolyte. A sulfide-based solid electrolyte is preferably used as the solid inorganic electrolyte. As the sulfide-based solid electrolyte, a solid electrolyte containing sulfur and lithium and having lithium ion conductivity may be used. As an example, the sulfide-based solid electrolyte may be one or more compounds selected from the group consisting of Li6PS5Cl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, and Li2S-P2S5.

[0112] The electrolyte may be a combination of the sulfide-based solid electrolyte with a crystalline oxide, an oxide-based amorphous solid electrolyte, or a crystalline oxynitride. 1.3 Al 0.3 Ti 0.7 (PO4)3, Li 1+x+y A x Ti 2-x Si y P 3-y O 12 (A is Al or Ga; 0≦x≦0.4; 0 <y≦0.6)、[(B 1 / 2 Li 1 / 2 ) 1-z C z ]TiO3 (B is La, Pr, Nd, or Sm; C is Sr or Ba; 0≦z≦0.5), Li5La3Ta2O 12 , Li7La3Zr2O 12 , Li6BaLa2Ta2O 12 , Li 3.6 Si 0.6 P 0.4 O4 and other crystalline oxides; oxide-based amorphous solid electrolytes such as Li2O-B2O3-P2O5, Li2O-SiO2, Li2O-B2O3, and Li2O-B2O3-ZnO; Li3PO (4-3 / 2w) N w (w<1); and / or LiI, LiI-Al2O3, Li3N, Li3N-LiI-LiOH, etc.

[0113] As another example, the electrolyte may include a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent may be any organic solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the non-aqueous organic solvent may be an ester-based solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, or ε-caprolactone; an ether-based solvent such as dibutyl ether or tetrahydrofuran; a ketone-based solvent such as cyclohexanone; an aromatic hydrocarbon-based solvent such as benzene or fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), or propylene carbonate (propylene carbonate). Examples of suitable solvents include carbonate solvents such as propylene carbonate (PC); alcohol solvents such as ethanol and isopropyl alcohol; nitriles such as R-CN (R is a C2-C20 linear, branched, or cyclic hydrocarbon group that may contain a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolane.

[0114] The lithium salt contained in the electrolyte dissolves in the non-aqueous organic solvent and acts as a lithium ion source within the battery, enabling basic lithium secondary battery operation and promoting the movement of lithium ions between the positive and negative electrodes. Specifically, the lithium salt may be LiPF, LiClO, LiAsF, LiBF, LiSbF, LiAlO, LiAlCl, LiCF, SO, LiCF, SO, LiN(CF, SO), LiN(CF, SO), LiN(CF, SO), LiFSI, LiTFSI, LiCl, LiI, and LiB(C, O) . Preferably, the lithium salt may be LiPF, LiFSI, LiTFSI, or a mixture thereof. The lithium salt may be contained in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt contained in this concentration range provides the electrolyte with appropriate conductivity and viscosity, thereby exhibiting excellent electrolyte performance.

[0115] Optionally, the cathode material may further include a binder, which can be used to better adhere the cathode material to the current collector.

[0116] Non-limiting examples of the binder include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc. The binder may be one or a mixture of two or more of the above examples.

[0117] The content of the binder can be adjusted within a range that provides an appropriate level of adhesiveness without causing a decrease in battery capacity, and is preferably 1 wt % to 10 wt % or 1 wt % to 5 wt % based on the total weight of the cathode material.

[0118] The negative electrode can be manufactured by coating a negative electrode material containing a negative electrode active material, a conductive material, and an electrolyte on a current collector and then drying the coating.

[0119] According to one embodiment, the negative electrode active material includes a compound that exhibits a lower charge / discharge potential than the positive electrode active material. In the present invention, there is no clear distinction between the positive electrode active material and the negative electrode active material, and by comparing the two types of charge / discharge potential, one that exhibits a relatively higher potential can be used as the positive electrode active material, and one that exhibits a relatively lower potential can be used as the negative electrode active material.

[0120] The conductive material contained in the negative electrode material is substituted for the content described above for the positive electrode.

[0121] As the current collector, any material known in the art to which the present invention pertains as being applicable to electrodes of lithium secondary batteries can be used without any particular limitation.

[0122] Non-limiting examples of the current collector include stainless steel; aluminum; nickel; titanium; baked carbon; or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like.

[0123] Preferably, the current collector has a thickness of 3 μm to 500 μm. The current collector may have a surface with fine irregularities to enhance the adhesive strength of the electrode material. The current collector may have various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0124] According to one embodiment, the lithium secondary battery can be manufactured by stacking the positive electrode, the electrolyte, and the negative electrode in order and press-molding them. [Effects of the Invention]

[0125] According to the present invention, there are provided a positive electrode active material for a lithium secondary battery that can suppress side reactions with an electrolyte and exhibit excellent life characteristics and safety, a method for producing the same, and a lithium secondary battery including the same. [Brief explanation of the drawings]

[0126] [Figure 1] 1 is a cross-sectional view schematically illustrating the structure of a positive electrode active material for a lithium secondary battery according to an embodiment of the present invention. [Figure 2] 1 shows the results of X-ray diffraction analysis of a Li—Zn—Ta—O coating layer according to an embodiment of the present invention. [Figure 3] 1 shows the results of a transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDS) analysis of a Li—Zn—Ta—O coating layer according to one embodiment of the invention. [Figure 4] 1 shows the results of cross-sectional transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) analysis of a positive electrode active material according to an embodiment of the present invention. [Figure 5] 1 shows the results of a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) analysis of a positive electrode active material according to an embodiment of the present invention. [Figure 6] 1 shows the results of X-ray photoelectron spectroscopy (XPS) for a positive electrode active material according to an embodiment of the present invention. [Figure 7] 1 is a depth profile obtained by X-ray photoelectron spectroscopy (XPS) for a positive electrode active material according to an embodiment of the present invention. [Figure 8] 1 shows the results of a lifespan characteristic test for lithium secondary batteries according to an embodiment of the present invention and a comparative example. [Figure 9] 1 shows the results of a lifespan characteristic test for lithium secondary batteries according to an embodiment of the present invention and a comparative example. [Figure 10]1 shows the results of a rate characteristic test for lithium secondary batteries according to an embodiment of the present invention and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0127] According to one embodiment of the present invention, a coating layer disposed on the lithium transition metal oxide particles; The coating layer can provide a positive electrode active material for a lithium secondary battery, including lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O).

[0128] According to another embodiment of the present invention, a method for producing a lithium transition metal oxide particle is provided, comprising the steps of: providing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor; coating the precursor mixture onto the lithium transition metal oxide particles; and heat-treating the lithium transition metal oxide particles coated with the precursor mixture under an oxygen atmosphere. A method for producing a positive electrode active material for a lithium secondary battery can be provided.

[0129] According to yet another embodiment of the present invention, there is provided a lithium secondary battery including a positive electrode including the positive electrode active material, a negative electrode, and an electrolyte. [Example]

[0130] The functions and effects of the present invention will be described in more detail below through specific examples of the present invention. However, these examples are presented as examples for understanding the present invention. The following examples are not intended to limit the scope of the invention in any way, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope and technical concept of the present invention.

[0131] Example 1 Lithium transition metal oxide particles: LiNi 0.95 Co 0.03 Mn 0.015 Al 0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0132] A precursor mixture was prepared by stirring lithium ethoxide, tantalum ethoxide, and zinc acetate in ethanol, with the precursors being present in a lithium (Li):tantalum (Ta):zinc (Zn) molar ratio of 3:1:1.

[0133] 2 g of the lithium transition metal oxide particles were mixed with the precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the precursor mixture on the lithium transition metal oxide particles.

[0134] The lithium transition metal oxide particles coated with the precursor mixture were heat-treated in an oxygen atmosphere at 450°C for 1 hour in a heat treatment furnace to obtain a cathode active material having a Li-Zn-Ta-O coating layer disposed on the lithium transition metal oxide particles. The Li-Zn-Ta-O coating layer was 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0135] A cross section of the positive electrode active material was observed with a transmission electron microscope, and it was confirmed that the coating layer was formed on the lithium transition metal oxide particles to a thickness of 10 nm.

[0136] Example 2 A positive electrode active material having a Li-Zn-Ta-O coating layer disposed on the lithium transition metal oxide particles was obtained in the same manner as in Example 1, except that the content of the Li-Zn-Ta-O coating layer was 1.0 part by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0137] Example 3 A positive electrode active material having a Li-Zn-Ta-O coating layer disposed on the lithium transition metal oxide particles was obtained in the same manner as in Example 1, except that the Li-Zn-Ta-O coating layer was adjusted to 2.0 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0138] Comparative Example 1 LiNi 0.95 Co 0.03 Mn 0.015 Al 0.005 Lithium transition metal oxide particles, which are secondary particles of O2 (particle size 4 μm), were prepared as the positive electrode active material.

[0139] Comparative Example 2 Lithium transition metal oxide particles: LiNi 0.95 Co 0.03 Mn 0.015 Al 0.005O2 Secondary particles (particle size 4 μm) were prepared.

[0140] A precursor mixture was prepared by stirring lithium ethoxide and zinc acetate in ethanol, with the precursors being present in a lithium (Li):zinc (Zn) molar ratio of 2:1.

[0141] 2 g of the lithium transition metal oxide particles were mixed with the precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the precursor mixture on the lithium transition metal oxide particles.

[0142] The lithium transition metal oxide particles coated with the precursor mixture were heat-treated in an oxygen atmosphere at 450°C for 1 hour in a heat treatment furnace to obtain a cathode active material having a coating layer containing a Li-Zn-O-based compound located on the lithium transition metal oxide particles. The Li-Zn-O-based compound was present in an amount of 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0143] Comparative Example 3 Lithium transition metal oxide particles: LiNi 0.95 Co 0.03 Mn 0.015 Al 0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0144] A precursor mixture was prepared by stirring lithium ethoxide and tantalum ethoxide in ethanol, with the precursors being present in a lithium (Li):tantalum (Ta) molar ratio of 3:1.

[0145] 2 g of the lithium transition metal oxide particles were mixed with the precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the precursor mixture on the lithium transition metal oxide particles.

[0146] The lithium transition metal oxide particles coated with the precursor mixture were heat-treated in an oxygen atmosphere at 450°C for 1 hour in a heat treatment furnace to obtain a cathode active material having a coating layer containing a Li-Ta-O-based compound (Li3TaO4) located on the lithium transition metal oxide particles. The Li-Ta-O-based compound was used in an amount of 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0147] Comparative Example 4 Lithium transition metal oxide particles: LiNi 0.95 Co 0.03 Mn 0.015 Al0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0148] A precursor mixture was prepared by stirring lithium ethoxide and tantalum ethoxide in ethanol, with the precursors being present in a lithium (Li):tantalum (Ta) molar ratio of 1:1.

[0149] 2 g of the lithium transition metal oxide particles were mixed with the precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the precursor mixture on the lithium transition metal oxide particles.

[0150] The lithium transition metal oxide particles coated with the precursor mixture were heat-treated in an oxygen atmosphere at 450°C for 1 hour in a heat treatment furnace to obtain a cathode active material having a coating layer containing a Li-Ta-O-based compound (LiTaO3) located on the lithium transition metal oxide particles. The Li-Ta-O-based compound was used in an amount of 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0151] Experimental Example 1 The Li-Zn-Ta-O coating layer of the positive electrode active material of Example 1 was subjected to X-ray diffraction analysis using Cu Kα radiation as a radiation source (Model: MiniFlex600, Manufacturer: Rigaku), and the results are shown in Figure 2. The analysis was performed by measuring the temperature range from 10 to 80 degrees at 1.5 degrees per minute at 40 kV and 15 mA.

[0152] As can be seen from FIG. 2, the Li-Zn-Ta-O coating layer exhibits a broad X-ray diffraction (XRD) pattern that generally indicates amorphous or low-crystalline properties, and the presence of a ZnO peak indicates that ZnO is a complex rather than integrated into a solid solution.

[0153] Experimental Example 2 The Li-Zn-Ta-O coating layer of the positive electrode active material of Example 1 was analyzed by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) using a transmission electron microscope (manufacturer: JEOL, model name: JEM-ARM 200F (NEOARM)), and the results are shown in FIG. 3.

[0154] Figure 3 shows that the Li-Zn-Ta-O coating layer has a ZnO-LiTaO composite structure, which confirms that ZnO is segregated within the matrix rather than integrated into a solid solution within the ZnO-LiTaO composite.

[0155] Experimental Example 3 The positive electrode active material of Example 1 was subjected to cross-sectional transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) analysis using a transmission electron microscope (manufacturer: JEOL, model name: JEM-ARM 200F (NEOARM)), and the results are shown in FIG. 4.

[0156] Figure 4 shows the changes in the lithium (Li), tantalum (Ta), and zinc (Zn) contents depending on the depth from the surface of the lithium transition metal oxide particles. The intensity of the Ta signal decreased sharply within a depth of 15 nm from the surface of the lithium transition metal oxide particles, whereas the Zn signal decreased relatively consistently up to a depth of 25 nm from the surface of the lithium transition metal oxide particles.

[0157] Therefore, it can be seen that in the positive electrode active material for a lithium secondary battery according to an embodiment of the present invention, some materials of the coating layer are diffused onto the surface of the lithium transition metal oxide particles in the positive electrode active material.

[0158] Experimental Example 4 The positive electrode active material of Example 1 was subjected to scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) analysis using a scanning electron microscope (manufacturer: ZEISS, model name: Crossbeam540), and the results are shown in FIG.

[0159] From FIG. 5, it can be seen that tantalum (Ta) and zinc (Zn) are present on the surfaces of the lithium transition metal oxide particles in the positive electrode active material.

[0160] Experimental Example 5 The positive electrode active material of Example 1 was subjected to X-ray photoelectron analysis (model name: K-alpha, manufacturer: Thermo Fisher Scientific), and the results are shown in Figures 6 and 7. The analysis was performed using an Al Kα radiation source under the condition of 3 mA.

[0161] As shown in FIG. 6, the Zn 2p and Ta 4f XPS spectra of the Li-Zn-Ta-O coating layer show characteristic peaks at 1021.2 eV and 26.2 eV, respectively, confirming that the layer contains ZnO and Li3TaO4.

[0162] FIG. 7 shows the results of etching the cathode active material of Example 1 and analyzing the elements present inside the active material. Zn was detected even at a depth of about 12 nm or more from the surface of the lithium transition metal oxide particles in the cathode active material, confirming that some of the material in the coating layer had diffused into the surface of the lithium transition metal oxide particles in the cathode active material.

[0163] Experimental Example 6 Using the positive electrode active materials obtained in the examples and comparative examples, an all-solid-state battery half-cell was manufactured by the following method. The positive electrode active material, solid electrolyte (Li6PS5Cl), and conductive material (carbon black) were mixed in ethanol in a mass ratio of 70:30:3 to manufacture a positive electrode composite electrode. 0.5A negative electrode material composite electrode was prepared by mixing Li6PS5Cl and a solid electrolyte (Li6PS5Cl) in a mass ratio of 80:20. The solid electrolyte (Li6PS5Cl) was pressed into a pellet shape. The positive electrode material composite electrode, the pellet-shaped solid electrolyte, and the negative electrode material composite electrode were stacked in order and pressed under 370 MPa to prepare an all-solid-state battery half cell.

[0164] The battery performance of the all-solid-state battery half-cell was evaluated at 30°C and a driving pressure of 70 MPa, and the results are shown in Table 1 below and Figures 8 to 10. At this time, the life characteristics were evaluated at 0.1C for 2 cycles based on 1C=200mA / g, and then at 0.5C.

[0165] [Table 1]

[0166] Referring to the results of the above experimental example, the lithium secondary battery including the positive electrode active material of the example achieved a current of 191 mA hg in the first cycle at 0.1 C. -1 It shows a high discharge capacity of 161mA hg even at 0.5C. -1 It was confirmed that the capacity was above 95% and the lifespan characteristics were also high performance of 95% or more.

[0167] In contrast, the lithium secondary batteries containing the cathode active materials of the comparative examples showed lower discharge capacities than the examples in the first cycle at 0.1 C, and also showed lower discharge capacities at 0.5 C. In some comparative examples, the capacity was reduced, which appeared to be excellent in lifespan characteristics, but overall, it was confirmed that the performance was inferior to that of Example 1.

[0168] Although the present invention has been described above using limited examples, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Industrial Applicability]

[0169] The present invention is applicable to a positive electrode active material for a lithium secondary battery and a lithium secondary battery including the same.

Claims

1. a coating layer disposed on the lithium transition metal oxide particles; The coating layer comprises lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O), Positive electrode active material for lithium secondary batteries.

2. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the coating layer is included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the positive electrode active material for a lithium secondary battery.

3. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the coating layer has a thickness of 1 nm to 200 nm.

4. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the coating layer is positioned on an area of ​​60% or more of the total surface area of ​​the lithium transition metal oxide particles.

5. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the lithium transition metal oxide particles have a layered structure.

6. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein a region from the surface of the lithium transition metal oxide particle to a depth of 30 nm contains zinc (Zn).

7. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the content of zinc (Zn) is 0.4% or more and less than 1% when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a depth of 15 nm from the surface of the lithium transition metal oxide particle is taken as 100%.

8. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the content of zinc (Zn) is 0.3% or more and 0.9% or less when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a depth of 25 nm from the surface of the lithium transition metal oxide particle is taken as 100%.

9. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the lithium transition metal oxide particles have a particle size of 2 μm to 50 μm.

10. The lithium transition metal oxide particles are Li ａ A １－ｂ R ｂ D ２ (0.90≦a≦1.8, 0≦b≦0.5); Li ａ E １－ｂ R ｂ O ２－ｃ D ｃ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05); LiE ２－ｂ R ｂ O ４－ｃ D ｃ (0≦b≦0.5, 0≦c≦0.05); Li ａ Ni １－ｂ－ｃ Co ｂ R ｃ D ｄ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<d≦2); Li ａ Ni １－ｂ－ｃ Co ｂ R ｃ O ２－ｄ Z ｄ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<d<2); Li ａ Ni １－ｂ－ｃ Co ｂ R ｃ O ２－ｄ Z ２ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<d<2); Li ａ Ni １－ｂ－ｃ Mn ｂ R ｃ D ｄ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<d≦2); Li ａ Ni １－ｂ－ｃ Mn ｂ R ｃ O ２－ｄ Z ｄ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<d<2); Li ａ Ni １－ｂ－ｃ Mn ｂ R ｃ O ２－ｄ Z ２ (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, 0<d<2); Li ａ Ni ｂ E ｃ G ｄ O ２ (0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0.001≦d≦0.1); Li ａ Ni ｂ Co ｃ Mn ｄ G ｅ O ２ (0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5, 0.001≦e≦0.1); Li ａ NiG ｂ O ２ (0.90≦a≦1.8, 0.001≦b≦0.1); Li ａ CoG ｂ O ２ (0.90≦a≦1.8, 0.001≦b≦0.1); Li ａ MnG ｂ O ２ (0.90≦a≦1.8, 0.001≦b≦0.1); Li ａ Mn ２ G ｂ O ４ (0.90≦a≦1.8, 0.001≦b≦0.1);QO ２ ;QS ２ ;LiQS ２ ;V ２ O ５ ; LiV ２ O ５ ; LiTO ２ ;LiNiVO ４ ; Li （３－ｆ） J ２ (P.O. ４ ) ３ (0≦f≦2);Li （３－ｆ） Fe ２ (P.O. ４ ) ３ (0≦f≦2); and LiFePO ４ The positive electrode active material for a lithium secondary battery according to claim 1, comprising one or more compounds selected from the group consisting of: A is Ni, Co, Mn, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; Z is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; T is Cr, V, Fe, Sc, Y, or a combination thereof; The J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

11. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the coating layer has a molar ratio of lithium (Li):tantalum (Ta):zinc (Zn) of 3:1:

1.

12. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the coating layer contains zinc oxide particles.

13. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the coating layer contains lithium tantalum oxide particles.

14. The coating layer is LiTaO ３ and Li ３ TaO ４ The positive electrode active material for a lithium secondary battery according to claim 1 , comprising at least one of:

15. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the lithium secondary battery is an all-solid-state battery.

16. The positive electrode active material for a lithium secondary battery according to claim 15, wherein the all-solid-state battery is a sulfide-based all-solid-state battery.

17. providing lithium transition metal oxide particles; providing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor; coating the precursor mixture onto the lithium transition metal oxide particles; and heat-treating the lithium transition metal oxide particles coated with the precursor mixture under an oxygen atmosphere. A method for producing a positive electrode active material for a lithium secondary battery.

18. the lithium (Li) precursor is an oxide containing lithium, The tantalum (Ta) precursor is an oxide containing tantalum, The method for producing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the zinc (Zn) precursor is an oxide, ammonium salt, or acetate containing zinc.

19. The method for producing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the precursor mixture is in the form of a solution obtained by stirring a lithium precursor, a tantalum precursor, and a zinc precursor in a solvent.

20. 18. The method for producing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the precursor mixture contains the precursors such that a molar ratio of lithium (Li):tantalum (Ta):zinc (Zn) is 3:1:

1.

21. The method for producing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the heat treatment is carried out at a temperature of 300°C to 1000°C.

22. The positive electrode active material for a lithium secondary battery produced by the method includes lithium transition metal oxide particles and a coating layer located on the lithium transition metal oxide particles, The method for producing a positive electrode active material for a lithium secondary battery according to claim 17 , wherein the coating layer contains zinc oxide particles and lithium tantalum oxide particles.

23. A lithium secondary battery comprising a positive electrode containing the positive electrode active material according to claim 1, a negative electrode, and an electrolyte.

24. 24. The lithium secondary battery according to claim 23, wherein the electrolyte is a sulfide-based solid electrolyte.

25. The sulfide-based solid electrolyte is Li ６ P.S. ５ Cl, Li ２ S-SiS ２ , LiI-Li ２ S-SiS ２ , LiI-Li ２ S-P ２ S ５ , LiI-Li ２ S-B ２ S ３ , Li ３ P.O. ４ -Li ２ S-Si ２ S., Li. ３ P.O. ４ -Li ２ S-SiS ２ , LiPO ４ -Li ２ S-SiS, LiI-Li ２ S-P ２ O ５ , LiI-Li ３ P.O. ４ -P ２ S ５ , and Li ２ S-P ２ S ５ 25. The lithium secondary battery according to claim 24, comprising one or more selected from the group consisting of:

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