Positive electrode active materials for lithium secondary batteries, method of manufacturing the same, and lithium secondary batteries comprising the same

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery comprising the same. According to the present invention, a positive electrode active material for a lithium secondary battery capable of exhibiting excellent lifespan characteristics and safety by suppressing side reactions with an electrolyte, a method for manufacturing the same, and a lithium secondary battery comprising the same are provided.

Description

Technology Field

[0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery comprising the same. Background Technology

[0003] As the demand for various electronic devices increases, the demand for lithium-ion batteries as an energy source is rapidly rising. Recently, the use of lithium-ion batteries as a power source for mobility hardware, such as electric vehicles (EVs) and hybrid electric vehicles (HEVs), has become widespread. Accordingly, many attempts are being made to improve the charge-discharge efficiency and lifespan characteristics of lithium-ion batteries.

[0004] Lithium secondary batteries using flammable organic dispersion media as electrolytes pose a risk of overheating and fire in the event of a short circuit. Consequently, interest in all-solid-state batteries, which use solid electrolytes instead of liquid electrolytes, is growing.

[0005] All-solid-state batteries utilize solid electrolytes such as polymeric electrolytes, inorganic electrolytes, and organic-inorganic composite electrolytes, and possess relatively superior safety as they do not contain flammable organic dispersion media.

[0006] In all-solid-state batteries, the cathode composite layer is mainly composed of a cathode active material, a solid electrolyte, and a conductive material. As the solid electrolyte, a sulfide-based solid electrolyte with excellent lithium ion conductivity can be used.

[0007] However, when sulfide-based solid electrolytes come into contact with the widely used lithium oxide-based cathode active material, 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 degrades the performance of the battery.

[0008] To address the aforementioned problems, many attempts are being made to improve battery performance by modifying the surface of the positive electrode active material. The problem to be solved

[0010] The present invention aims to provide a positive electrode active material for a lithium secondary battery that can exhibit excellent lifespan characteristics and safety by suppressing adverse reactions with the electrolyte.

[0011] The present invention is intended to provide a method for manufacturing a positive electrode active material for a lithium secondary battery.

[0012] In addition, the present invention is intended to provide a lithium secondary battery comprising the positive electrode active material for the lithium secondary battery. means of solving the problem

[0014] According to one embodiment of the invention,

[0015] It comprises lithium transition metal oxide particles and a coating layer located on the lithium transition metal oxide particles, and

[0016] The above coating layer comprises lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O).

[0017] A positive electrode active material for a lithium secondary battery is provided.

[0019] According to another embodiment of the invention,

[0020] Step of preparing lithium transition metal oxide particles,

[0021] Step of preparing lithium transition metal oxide particles;

[0022] A step of preparing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor;

[0023] A step of coating the precursor mixture onto the lithium transition metal oxide particles; and

[0024] The step of heat-treating the lithium transition metal oxide particles coated with the above precursor mixture under an oxygen atmosphere; comprising

[0025] A method for manufacturing a positive electrode active material for a lithium secondary battery is provided.

[0026] According to another embodiment of the invention, a lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte comprising the positive active material is provided.

[0028] Hereinafter, a positive electrode active material for a lithium secondary battery according to embodiments of the invention, a method for manufacturing the same, and a lithium secondary battery including the same, in particular an all-solid-state lithium secondary battery, will be described in more detail.

[0030] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical idea of ​​the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0031] Unless otherwise defined in this specification, all technical and scientific terms have the same meaning as generally understood by those skilled in the art to which the invention pertains. The terms used in the description of the invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the invention.

[0032] The singular forms used in this specification include plural forms unless the phrases clearly indicate otherwise.

[0033] As used in this specification, the meaning of “includes” specifies certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0034] The present invention is capable of various modifications and may take various forms, and specific embodiments are illustrated and described in detail below. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0035] In this specification, where the positional relationship between two parts is described, for example, using expressions such as 'on', 'on the upper part', 'on the lower part', 'next to', etc., one or more other parts may be located between the two parts unless expressions such as 'immediately' or 'directly' are used.

[0036] In this specification, when temporal sequences are described, for example, using expressions such as ‘after,’ ‘following,’ ‘next,’ or ‘before,’ cases that are not continuous may be included unless expressions such as ‘immediately’ or ‘directly’ are used.

[0037] In this specification, the term 'at least one' should be understood to include all combinations that can be presented from one or more related items.

[0039] According to one embodiment of the invention,

[0040] It comprises lithium transition metal oxide particles and a coating layer located on the lithium transition metal oxide particles, and

[0041] The above coating layer comprises lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O).

[0042] A positive electrode active material for a lithium secondary battery is provided.

[0044] As a result of the inventors' continued research, it was confirmed that an anode active material having a Li-Zn-Ta-O coating layer located on lithium transition metal oxide particles can exhibit excellent lifespan characteristics and safety by suppressing side reactions with the electrolyte.

[0045] The above 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 above Li-Zn-Ta-O coating layer can suppress the formation of a resistance layer caused by contact between the lithium transition metal oxide particles and the electrolyte, and can mitigate irreversible phase transitions of the lithium transition metal oxide particles. Accordingly, the cathode active material for the lithium secondary battery can exhibit superior lifespan characteristics and safety compared to one without the coating layer, and enables the provision of a lithium secondary battery with excellent cycle and rate capability characteristics.

[0046] Furthermore, some of the materials of the coating layer can be doped onto the surface of lithium transition metal oxide particles within the positive electrode active material to improve the structural stability of the positive electrode active material.

[0048] The positive electrode active material for the above lithium secondary battery includes the above lithium transition metal oxide particles.

[0049] As for the lithium transition metal oxide particles mentioned above, any material capable of reversible insertion and extraction of lithium ions may be used without special limitations. The lithium transition metal oxide particles may include conventionally known oxides comprising lithium, a transition metal, and oxygen. The lithium transition metal oxide particles include compounds that exhibit a higher charge / discharge potential than the material used as the negative electrode active material.

[0050] For example, the lithium transition metal oxide particles are 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 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 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 bO2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(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 include one or more compounds selected from the group consisting of Fe2(PO4)3 (0≤f≤2); and LiFePO4.

[0051] In the compounds exemplified above, 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.

[0053] The above lithium transition metal oxide particles may be primary particles or secondary particles formed by the aggregation of multiple primary particles.

[0054] The lithium transition metal oxide particles may have a particle size of 2 μm to 50 μm, or 2 μm to 25 μm, or 4 μm to 25 μm, or 4 μm to 20 μm, or 4 μm to 15 μm.

[0055] If the particle size of the lithium transition metal oxide particles is too small, controlling the particles is difficult, 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 desirable for the lithium transition metal oxide particles to have a particle size within the aforementioned range.

[0056] The particle size of the above lithium transition metal oxide particles can be confirmed through scanning electron microscope (SEM) images or transmission electron microscope (TEM) images taken of the particles.

[0058] As shown in FIG. 1, the positive electrode active material for the lithium secondary battery comprises a coating layer (hereinafter, Li-Zn-Ta-O coating layer) containing lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O) located on the lithium transition metal oxide particles.

[0059] There have been many attempts to improve the performance of batteries by modifying the surface of conventional cathode active materials. For example, phosphate-based coating layers have been used, but in this case, there was still a problem with low ionic conductivity and a problem with structural collapse due to volume change of Ni-rich cathode active materials, so the need for oxide-based coatings that are effective with only low-temperature heat treatment has emerged.

[0060] Meanwhile, tantalum (Ta) is a material that can suppress the formation of NiO on the surface of the positive electrode active material through doping due to the large difference in bonding energy with oxygen. After researching oxide-based coatings containing tantalum (Ta), the inventors confirmed 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 within the positive electrode active material, thereby improving structural stability, and thus completed the present invention.

[0061] It is confirmed that the coating layer contains lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O), and that tantalum (Ta) acts to preserve the coating layer, preventing direct contact with reactive materials, while zinc (Zn) helps structurally stabilize the cathode active material by diffusing to the surface of lithium transition metal oxide particles within the cathode active material and hindering the migration of nickel (Ni) within the particles, thereby exhibiting superior lifespan characteristics and safety.

[0062] According to one embodiment, tantalum (Ta) and zinc (Zn) elements can be evenly distributed within the coating layer.

[0063] 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 a lithium secondary battery can be maintained.

[0064] According to one embodiment, the molar ratio of lithium (Li): tantalum (Ta): zinc (Zn) in the coating layer may be 3:1:1.

[0065] According to one embodiment, the coating layer may include zinc oxide particles.

[0066] According to one embodiment, the coating layer may include lithium tantalum oxide particles.

[0067] According to one embodiment, the coating layer may include at least one of LiTaO3 and Li3TaO4.

[0068] According to one embodiment, the coating layer may include ZnO particles.

[0069] According to one embodiment, the ZnO particles may have a hexagonal crystal structure.

[0070] According to one embodiment, the coating layer may include Li3TaO4 particles.

[0071] According to one embodiment, the Li3TaO4 particles may have a monoclinic crystal structure.

[0072] According to one embodiment, at least some of the zinc oxide particles and lithium tantalum oxide particles within the coating layer may have a ZnO-LiTaO composite form.

[0073] According to one embodiment, the coating layer is a composite compound of ZnO-Li3TaO4 and / or It may include Li2O-ZnO-LiTaO3.

[0074] Meanwhile, some of the materials of the coating layer can be doped onto the surface of lithium transition metal oxide particles within the positive electrode active material to improve the structural stability of the positive electrode active material.

[0075] For example, as shown in FIG. 1, zinc (Zn) can partially diffuse onto the surface of lithium transition metal oxide particles within the cathode active material to have a surface doping effect. At this time, the zinc diffusing onto the surface of the lithium transition metal oxide particles is zinc ions (Zn2+ It can be in the form of ).

[0076] According to one 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 particles to a depth of 15 nm.

[0077] According to one 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 particles to a depth of 25 nm.

[0078] According to one 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 particles to a depth of 30 nm.

[0079] 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 particles to a depth of 15 nm.

[0080] 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 particles to a depth of 25 nm.

[0081] According to one embodiment, the positive electrode active material for a lithium secondary battery may include tantalum (Ta) diffused from the coating layer in the region from the surface of the lithium transition metal oxide particles to a depth of 30 nm. In this specification, when the total content of nickel (Ni), tantalum (Ta), and zinc (Zn) present at a specific depth from the surface of the lithium transition metal oxide particles is set to 100%, the content of each component is expressed as a %, which means the atomic percent composition ratio of Ni, Ta, and Zn present in the corresponding depth range. This atomic percent composition ratio can be measured through TEM-EDS, STEM-EDS line scan, EDS depth profile, or equivalent component analysis methods. The atomic percent composition ratio can be confirmed from the depth direction component distribution shown in Figure 4.

[0082] 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 set to 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.

[0083] 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 set to 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.

[0084] 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 set to 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.

[0085] 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 set to 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 0.5% or less, or 0.4% or less, or 0.3% or less.

[0086] According to one embodiment, the coating layer may be located on 60% or more, 70% or more, 80% or more, 90% or more, or the entire surface area based on the total surface area of ​​the lithium transition metal oxide particles. At this time, the upper limit of the coating area of ​​the coating layer is not specifically restricted, but, for example, it may be 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, in order to ensure that the above-described effect resulting from the introduction of the coating layer is sufficiently manifested, it is preferable that the coating layer be located on the entire surface area of ​​the lithium transition metal oxide particles.

[0087] If more than 40% of the areas on the surface of the lithium transition metal oxide particles are not coated, there is a risk that the lithium transition metal oxide particles and the electrolyte will react at those areas to form a high-resistance atmosphere.

[0088] According to one embodiment, the coating layer may be included in an amount of 0.1 to 10 parts by weight, or 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 the lithium secondary battery.

[0089] In order to sufficiently express the above-described effects resulting from the introduction of the coating layer, it is preferable that the coating layer be 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 the lithium secondary battery. However, if the content ratio of the coating layer is too high, the performance of the positive electrode active material expressed from the lithium transition metal oxide particles may be degraded. Therefore, it is preferable that the coating layer be included in an amount of 10 parts by weight or less based on 100 parts by weight of the positive electrode active material for the lithium secondary battery.

[0091] The above coating layer can be formed with a thickness that can stably suppress the reaction between the lithium transition metal oxide particles and the electrolyte while ensuring lithium ion conductivity.

[0092] According to one embodiment, the coating layer may have a thickness of 1 nm to 200 nm, or 1 nm to 150 nm, or 1 nm to 100 nm.

[0093] If the thickness of the coating layer is too thin, it may be difficult to ensure the stability of the coating layer. Also, if the thickness of the coating layer is too thin, uncoated areas may occur on the surface of the lithium transition metal oxide particles, and there is a risk that high-resistance regions may be formed at those areas due to the reaction between the lithium transition metal oxide particles and the electrolyte. However, if the thickness of the coating layer is too thick, the lithium ion conductivity may decrease.

[0094] 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 the lithium secondary battery. Alternatively, the thickness of the coating layer can be confirmed by observing a cross- section of the positive electrode active material using a transmission electron microscope (TEM).

[0095] According to one embodiment, the lithium secondary battery may be an all-solid-state battery.

[0096] According to one embodiment, the all-solid-state battery may be a sulfide-based all-solid-state battery.

[0098] According to another embodiment of the invention,

[0099] Step of preparing lithium transition metal oxide particles;

[0100] A step of preparing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor;

[0101] A step of coating the precursor mixture onto the lithium transition metal oxide particles; and

[0102] The step of heat-treating the lithium transition metal oxide particles coated with the above precursor mixture under an oxygen atmosphere; comprising

[0103] A method for manufacturing a positive electrode active material for a lithium secondary battery is provided.

[0105] First, a step of preparing lithium transition metal oxide particles is performed.

[0106] As the lithium transition metal oxide particles mentioned above, conventionally known oxides containing lithium, a transition metal, and oxygen may be prepared. The description of the lithium transition metal oxide particles above is substituted with the previously explained details.

[0108] A step of preparing a precursor mixture including a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor is performed.

[0109] The above precursor mixture can be prepared in a solution phase by placing a lithium precursor, a tantalum precursor, and a zinc precursor into a suitable solvent, such as an alcohol, and stirring.

[0110] As the above lithium precursor, oxides containing lithium, such as Li2O, CH3OLi, and CH3CH2OLi, may be used without special limitations.

[0111] As the above tantalum precursor, oxides containing tantalum, such as (CH3O)5Ta and (CH3CH2O)5Ta, may be used without special limitations.

[0112] As the above zinc precursor, zinc-containing oxides, ammonium salts, acetates, etc., may be used without special restrictions.

[0114] According to one embodiment, the precursor mixture may include lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O) to match the desired composition.

[0115] Preferably, the precursor mixture may include the precursors such that the molar ratio of lithium (Li): tantalum (Ta): zinc (Zn) is 3:1:1.

[0117] A step of coating the precursor mixture onto the lithium transition metal oxide particles is performed.

[0118] According to one embodiment, the coating step may be performed by introducing the lithium transition metal oxide particles into the precursor mixture in a solution, stirring, and drying to remove the solvent contained in the precursor mixture.

[0119] By controlling the composition and solid content of the precursor mixture in the above coating step, the content, thickness, and area ratio of the coating layer applied to the anode active material can be controlled.

[0121] A step of heat-treating the lithium transition metal oxide particles coated with the above precursor mixture under an oxygen atmosphere is performed.

[0122] According to one embodiment, the heat treatment may be performed at a temperature of 300 ℃ or higher, or 300 ℃ to 1000 ℃, or 350 ℃ to 1000 ℃, or 350 ℃ to 900 ℃, or 400 ℃ to 800 ℃.

[0123] If the above 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 be reduced. However, if the above heat treatment temperature is too high, it may cause deformation of the lithium transition metal oxide particles or the material of the coating layer. Therefore, it is preferable that the heat treatment be performed within the temperature range described above.

[0124] In addition, the heat treatment may be performed for 0.5 to 12 hours at the heat treatment temperature. The heat treatment time may be adjusted considering the time required for the Li-Zn-Ta-O coating layer to stabilize.

[0126] By performing the steps described above, a positive electrode active material for a lithium secondary battery can be manufactured, comprising the lithium transition metal oxide particles and the coating layer located on the lithium transition metal oxide particles.

[0127] The positive electrode active material for a lithium secondary battery manufactured by the above manufacturing method comprises lithium transition metal oxide particles and a coating layer located on the lithium transition metal oxide particles, wherein the coating layer may comprise zinc oxide particles and lithium tantalum oxide particles.

[0128] The coating layer may include at least one of LiTaO3 and Li3TaO4.

[0129] The above coating layer may include ZnO particles.

[0130] The above ZnO particles may have a hexagonal crystal structure.

[0131] The above coating layer may contain Li3TaO4 particles.

[0132] The above Li3TaO4 particles may have a monoclinic crystal structure.

[0133] At least some of the zinc oxide particles and lithium tantalum oxide particles within the coating layer may have a ZnO-LiTaO composite form.

[0134] The above coating layer is a composite compound of ZnO-Li3TaO4 and / or It may include Li2O-ZnO-LiTaO3.

[0135] The description of the coating layer above is as described above.

[0137] According to another embodiment of the invention, a lithium secondary battery is provided, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode active material described above is included.

[0138] The above lithium secondary battery comprises a positive electrode containing the above positive electrode active material. Accordingly, the above lithium secondary battery can exhibit excellent cycle characteristics and rate capability while having excellent lifespan characteristics and safety.

[0139] Accordingly, the lithium secondary battery can be used as an energy source with enhanced performance and safety in the field of portable electronic devices such as mobile phones, laptop computers, tablet computers, mobile batteries, and digital cameras; and in the field of means of transportation such as electric vehicles, electric motorcycles, and personal mobility devices.

[0141] The above anode can be manufactured using a mixture of the above anode active material, conductive material, and electrolyte.

[0142] According to one embodiment, the positive active material may be included in an amount of 70% to 95% by weight relative to the total weight of the positive material.

[0143] Specifically, the content of the positive active material may be 70% by weight or more, or 80% by weight or more, or 85% by weight or more, relative to the total weight of the positive material; and, 95% by weight or less, or 93% by weight or less, or 90% by weight or less. Preferably, the content of the positive active material may be 70% by weight to 95% by weight, or 80% by weight to 95% by weight, or 85% by weight to 93% by weight, or 85% by weight to 90% by weight, relative to the total weight of the positive material.

[0145] The above conductive material is used to impart conductivity to the electrode.

[0146] The above conductive material may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes in the battery. As a non-limiting example, the above conductive material may be carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; graphite such as natural graphite or artificial graphite; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; or conductive polymers such as polyphenylene derivatives. As the above conductive material, one or more of the examples described above may be used.

[0147] The content of the conductive material can be adjusted within a range that does not cause a reduction in battery capacity while exhibiting an appropriate level of conductivity. Preferably, the content of the conductive material may be 1% to 10% by weight or 1% to 5% by weight relative to the total weight of the cathode material.

[0149] Any electrolyte known to be applicable to lithium secondary batteries in the technical field to which the present invention belongs may be used without special limitations. For example, the electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc.

[0150] For example, the electrolyte may be a solid inorganic electrolyte. A sulfide-based solid electrolyte may preferably be 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. For 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.

[0151] In addition, the above electrolyte may be used by combining the above sulfide-based solid electrolyte with a crystalline oxide, an oxide-based amorphous solid electrolyte, or a crystalline oxynitrate product. As an example, the above electrolyte may be the above sulfide-based solid electrolyte and Li 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 Crystalline oxides such as O4; oxide-based amorphous solid electrolytes such as Li2O-B2O3-P2O5, Li2O-SiO2, Li2O-B2O3, Li2O-B2O3-ZnO; Li3PO (4-3 / 2w) N w Crystalline oxynitrides such as (w<1); and / or combinations of LiI, LiI-Al2O3, Li3N, Li3N-LiI-LiOH, etc. may be used.

[0152] As another example, the electrolyte may comprise a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the non-aqueous organic solvent may be ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether and tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having C2 to C20 structures and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolane, etc.

[0153] The lithium salt included in the electrolyte is dissolved in the non-aqueous organic solvent and acts as a source of lithium ions within the battery, enabling the operation of a basic lithium secondary battery and facilitating the movement of lithium ions between the positive and negative electrodes. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiFSI, LiTFSI, LiCl, LiI, and LiB(C2O4)2, etc. Preferably, the lithium salt may be LiPF6, LiFSI, LiTFSI, and mixtures thereof. The lithium salt may be included in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt included in the above concentration range enables excellent electrolyte performance by imparting appropriate conductivity and viscosity to the electrolyte.

[0154] Optionally, the anode material may further include a binder. The binder may be used to properly attach the anode material to the current collector.

[0155] As a non-limiting example, the binder may be polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc. As the binder, one or more of the examples described above may be used.

[0156] The content of the binder can be adjusted within a range that does not cause a reduction in battery capacity while exhibiting an appropriate level of adhesion. Preferably, the content of the binder may be 1% to 10% by weight or 1% to 5% by weight relative to the total weight of the cathode material.

[0158] The above cathode can be manufactured by applying a cathode material comprising a cathode active material, a conductive material, and an electrolyte onto a current collector and then drying it.

[0160] According to one embodiment, the negative electrode active material comprises a compound that exhibits a charge-discharge potential lower than that of 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 potentials, the one exhibiting a relatively higher potential can be used as the positive electrode active material, and the one exhibiting a relatively lower potential can be used as the negative electrode active material.

[0161] The conductive material included in the above-mentioned cathode material is replaced by the description of the above-mentioned anode.

[0163] As the above current collector, any material known to be applicable to electrodes of lithium secondary batteries in the technical field to which the present invention belongs may be used without special limitations.

[0164] As a non-limiting example, the current collector may be stainless steel; aluminum; nickel; titanium; calcined carbon; or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc.

[0165] Preferably, the current collector may have a thickness of 3 μm to 500 μm. In order to increase the adhesion of the electrode material, the current collector may have fine irregularities formed on its surface. The current collector may have various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0167] According to one embodiment, the lithium secondary battery can be manufactured by sequentially overlapping the positive electrode, the electrolyte, and the negative electrode and then pressurizing them. Effects of the invention

[0169] According to the present invention, a positive electrode active material for a lithium secondary battery capable of exhibiting excellent lifespan characteristics and safety by suppressing adverse reactions with an electrolyte, a method for manufacturing the same, and a lithium secondary battery including the same are provided. Brief explanation of the drawing

[0171] FIG. 1 is a cross-sectional view schematically showing the structure of a positive electrode active material for a lithium secondary battery according to an embodiment of the invention. Figure 2 is the result of X-ray diffraction analysis of a Li-Zn-Ta-O coating layer according to one embodiment of the invention. Figure 3 shows the transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDS) analysis results for a Li-Zn-Ta-O coating layer according to one embodiment of the invention. Figure 4 is the result of cross-section transmission electron microscopy - energy dispersive X-ray spectroscopy (cross-section TEM-EDS) analysis of a positive electrode active material according to one embodiment of the invention. Figure 5 is the result of scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) analysis of a positive electrode active material according to one embodiment of the invention. Figure 6 is the X-ray photoelectron analysis (XPS) result for a positive electrode active material according to one embodiment of the invention. FIG. 7 is a depth profile obtained through X-ray photoelectron analysis (XPS) of a positive electrode active material according to one embodiment of the invention. Figures 8 and 9 are the results of a lifespan characteristic test for a lithium secondary battery according to an embodiment and a comparative example of the invention. Figure 10 shows the results of a rate capability test for a lithium secondary battery according to an embodiment and a comparative example of the invention. Specific details for implementing the invention

[0172] The operation and effects of the invention will be explained in more detail through the specific embodiments described below. However, these are presented merely as examples to aid in understanding the invention. The following embodiments 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 spirit of the invention.

[0174] Example 1

[0175] LiNi as lithium transition metal oxide particles 0.95 Co 0.03 Mn 0.015 Al 0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0176] A precursor mixture was prepared by adding lithium ethoxide, tantalum ethoxide, and zinc acetate to ethanol and stirring. The precursor mixture contained the precursors such that the molar ratio of lithium (Li): tantalum (Ta): zinc (Zn) was 3:1:1.

[0177] 2 g of the above lithium transition metal oxide particles were mixed with the above precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the above precursor mixture onto the above lithium transition metal oxide particles.

[0178] The lithium transition metal oxide particles coated with the above precursor mixture were heat-treated in a heat treatment furnace under an oxygen atmosphere and at a temperature of 450°C for 1 hour to obtain an anode active material having a Li-Zn-Ta-O coating layer located on the lithium transition metal oxide particles. The Li-Zn-Ta-O coating layer is 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0179] The cross-section of the above-mentioned positive active material was observed using a transmission electron microscope, and it was confirmed that the coating layer was coated on the lithium transition metal oxide particles with a thickness of 10 nm.

[0181] Example 2

[0182] A positive electrode active material having a Li-Zn-Ta-O coating layer positioned 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.

[0184] Example 3

[0185] A positive electrode active material having a Li-Zn-Ta-O coating layer positioned on the lithium transition metal oxide particles was obtained in the same manner as in Example 1, except that the amount of the Li-Zn-Ta-O coating layer was 2.0 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0187] Comparative Example 1

[0188] 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.

[0190] Comparative Example 2

[0191] LiNi as lithium transition metal oxide particles 0.95 Co 0.03 Mn 0.015 Al 0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0192] A precursor mixture was prepared by adding lithium ethoxide and zinc acetate to ethanol and stirring. The precursor mixture contained the precursors such that the molar ratio of lithium (Li):zinc (Zn) was 2:1.

[0193] 2 g of the above lithium transition metal oxide particles were mixed with the above precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the above precursor mixture onto the above lithium transition metal oxide particles.

[0194] The lithium transition metal oxide particles coated with the above precursor mixture were heat-treated in a heat treatment furnace under an oxygen atmosphere and at a temperature of 450 °C for 1 hour to obtain an anode 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 is 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0196] Comparative Example 3

[0197] LiNi as lithium transition metal oxide particles 0.95 Co 0.03 Mn 0.015 Al 0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0198] A precursor mixture was prepared by adding lithium ethoxide and tantalum ethoxide to ethanol and stirring. The precursor mixture contained the precursors such that the molar ratio of lithium (Li) to tantalum (Ta) was 3:1.

[0199] 2 g of the above lithium transition metal oxide particles were mixed with the above precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the above precursor mixture onto the above lithium transition metal oxide particles.

[0200] The lithium transition metal oxide particles coated with the above precursor mixture were heat-treated in a heat treatment furnace under an oxygen atmosphere and at a temperature of 450 °C for 1 hour to obtain an anode 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 is 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0202] Comparative Example 4

[0203] LiNi as lithium transition metal oxide particles 0.95 Co 0.03 Mn 0.015 Al 0.005 Secondary particles of O2 (particle size 4 μm) were prepared.

[0204] A precursor mixture was prepared by adding lithium ethoxide and tantalum ethoxide to ethanol and stirring. The precursor mixture contained the precursors such that the molar ratio of lithium (Li) to tantalum (Ta) was 1:1.

[0205] 2 g of the above lithium transition metal oxide particles were mixed with the above precursor mixture and stirred for 30 minutes, and the solvent (ethanol) was evaporated for 30 minutes using a rotary evaporator to coat the above precursor mixture onto the above lithium transition metal oxide particles.

[0206] The lithium transition metal oxide particles coated with the above precursor mixture were heat-treated in a heat treatment furnace under an oxygen atmosphere and at a temperature of 450 °C for 1 hour to obtain an anode 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 is 1.5 parts by weight based on 100 parts by weight of the lithium transition metal oxide particles.

[0208] Experimental Example 1

[0209] X-ray diffraction analysis (model name: MiniFlex600, manufacturer: Rigaku) ​​was performed on the Li-Zn-Ta-O coating layer of the positive electrode active material of Example 1 using CuKα rays as a source, and the results are shown in Fig. 2. The analysis was performed by measuring the range from 10 to 80 degrees at 1.5 degrees per minute at 40 kV and 15 mA.

[0210] According to Figure 2, it can be confirmed that the Li-Zn-Ta-O coating layer exhibits a broad X-ray diffraction (XRD) pattern that is generally amorphous or low-crystallinity, and the presence of a ZnO peak indicates that ZnO is formed as a complex rather than being integrated into a solid solution.

[0212] Experimental Example 2

[0213] Transmission electron microscopy - energy dispersive X-ray spectroscopy (TEM-EDS) analysis was performed on the Li-Zn-Ta-O coating layer of the positive electrode active material of Example 1 using a transmission electron microscope (Manufacturer: JEOL, Model: JEM-ARM 200F (NEOARM)), and the results are shown in Figure 3.

[0214] Figure 3 shows that the Li-Zn-Ta-O coating layer has a ZnO-LiTaO composite structure. Through this, it can be confirmed that ZnO is separated within the matrix rather than being integrated into a solid solution within the ZnO-LiTaO composite.

[0216] Experimental Example 3

[0217] Cross-section transmission electron microscopy - energy dispersive X-ray spectroscopy (cross-section TEM-EDS) analysis was performed on the cathode active material of Example 1 using a transmission electron microscope (manufacturer: JEOL, model name: JEM-ARM 200F (NEOARM)), and the results are shown in Figure 4.

[0218] According to Figure 4, changes in the content of lithium (Li), tantalum (Ta), and zinc (Zn) with depth from the surface of the lithium transition metal oxide particles can be observed. 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 with relative consistency up to a depth of 25 nm from the surface of the lithium transition metal oxide particles.

[0219] Through this, it can be confirmed that in the positive electrode active material for a lithium secondary battery according to one embodiment of the present invention, some materials of the coating layer diffuse to the surface of lithium transition metal oxide particles within the positive electrode active material.

[0221] Experimental Example 4

[0222] Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis was performed on the positive electrode active material of Example 1 using a scanning electron microscope (manufacturer: ZEISS, model name: Crossbeam 540), and the results are shown in Figure 5.

[0223] According to Figure 5, it can be confirmed that tantalum (Ta) and zinc (Zn) are present on the surface of lithium transition metal oxide particles within the positive electrode active material.

[0225] Experimental Example 5

[0226] X-ray photoelectron analysis (model name: K-alpha, manufacturer: Thermo Fisher Scientific) was performed on the cathode active material of Example 1 above, and the results are shown in Figures 6 and 7. The analysis was performed using an Al Kα source under conditions of 3 mA.

[0227] According to Figure 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 they contain ZnO and Li3TaO4.

[0228] Figure 7 shows the results of analyzing the elements present inside the active material while etching the positive electrode active material of Example 1. Since Zn can be detected even at a depth of about 12 nm or more from the surface of the lithium transition metal oxide particles in the positive electrode active material, it can be confirmed that some materials of the coating layer are diffused to the surface of the lithium transition metal oxide particles in the positive electrode active material.

[0230] Experimental Example 6

[0231] An all-solid-state battery half-cell was manufactured using the positive active material obtained in the above examples and comparative examples in the following manner. A positive composite electrode was prepared by mixing the positive active material, a solid electrolyte (Li6PS5Cl), and a conductive material (carbon black) in ethanol at a mass ratio of 70:30:3. The negative active material (Li 0.5 A cathode composite electrode was prepared by mixing In and a solid electrolyte (Li6PS5Cl) in a mass ratio of 80:20. The solid electrolyte (Li6PS5Cl) was pressurized to form a pellet. An all-solid-state battery half-cell was prepared by sequentially stacking the cathode composite electrode, the pellet-shaped solid electrolyte, and the cathode composite electrode and pressurizing them at 370 M Pa.

[0232] The battery performance of the above-mentioned all-solid-state battery half-cell was evaluated at a driving pressure of 70 M Pa at 30 ℃, and the results are shown in Table 1 and Figures 8 to 10 below. At this time, the life characteristics were evaluated at 0.1 C for 2 cycles and then at 0.5 C based on 1 C = 200 mA / g.

[0234] positive electrode active material 1 st charge capacity[mA h g -1 ] 1 st discharge capacity[mA h g -1 ] Initial columbic efficiency [%] 3 rd discharge(0.5C) capacity[mA h g -1 ] 3 rd / 52 nd retention[%] Example 1 243.6 196.3 80.6 173.8 95.8 Example 2 243.2 194.3 79.9 161.0 96.3 Example 3 242.3 191.1 78.9 167.8 95.7 Comparative Example 1 245.1 189.6 77.5 154.5 88.7 Comparative Example 2 228.5 182.0 79.6 158.0 97.7 Comparative Example 3 243.3 190.5 78.3 160.6 91.9 Comparative Example 4 237.7 185.8 78.2 151.6 92.4

[0236] Referring to the results of the above experimental examples, the lithium secondary battery containing the positive electrode active material of the examples has 191 mA hg at the first cycle of 0.1C. -1 It exhibited a high discharge capacity of the above, and 161 mA hg even at 0.5C -1 It was confirmed that the above capacity was displayed, and the lifespan characteristics also showed high performance of over 95%.

[0237] In contrast, the lithium secondary batteries containing the positive electrode active materials of the comparative examples exhibited a lower discharge capacity compared to the examples in the first cycle at 0.1C, and also exhibited a lower discharge capacity at 0.5C. Although some comparative examples showed lower capacities and appeared to have superior lifespan characteristics, it was confirmed that overall performance was inferior to Example 1.

[0238] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

Claim 1 A positive electrode active material for a lithium secondary battery, comprising lithium transition metal oxide particles and a coating layer located on the lithium transition metal oxide particles, wherein the coating layer comprises lithium (Li), tantalum (Ta), zinc (Zn), and oxygen (O), and wherein the coating layer comprises zinc oxide particles and lithium tantalum oxide particles. Claim 2 A 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. Claim 3 A positive electrode active material for a lithium secondary battery, wherein the coating layer has a thickness of 1 nm to 200 nm in claim 1. Claim 4 A positive electrode active material for a lithium secondary battery according to claim 1, wherein the coating layer is located over an area of ​​at least 60% of the total surface area of ​​the lithium transition metal oxide particles. Claim 5 In claim 1, the lithium transition metal oxide particles have a layered structure, a positive electrode active material for a lithium secondary battery. Claim 6 A positive electrode active material for a lithium secondary battery according to claim 1, wherein the region from the surface of the lithium transition metal oxide particle to a depth of 30 nm comprises zinc (Zn). Claim 7 A positive electrode active material for a lithium secondary battery according to claim 1, wherein 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 100 atomic%, and the content of zinc (Zn) is 0.4 atomic% or more and less than 1 atomic%. Claim 8 A positive electrode active material for a lithium secondary battery according to claim 1, wherein, 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 100 atomic%, the content of zinc (Zn) is 0.3 atomic% or more and 0.9 atomic% or less. Claim 9 A positive electrode active material for a lithium secondary battery, wherein the lithium transition metal oxide particles have a particle size of 2 μm to 50 μm. Claim 10 In claim 1, the lithium transition metal oxide particles are 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 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 Z2(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 Z2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <d<2); Li a Ni b E 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 Mn 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 b O2(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) A positive electrode active material for a lithium secondary battery comprising one or more compounds selected from the group consisting of Fe2(PO4)3 (0≤f≤2); and LiFePO4: wherein 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. Claim 11 A positive electrode active material for a lithium secondary battery according to claim 1, wherein the molar ratio of lithium (Li): tantalum (Ta): zinc (Zn) in the coating layer is 3:1:

1. Claim 12 delete Claim 13 delete Claim 14 A positive electrode active material for a lithium secondary battery according to claim 1, wherein the coating layer comprises at least one of LiTaO3 and Li3TaO4. Claim 15 In claim 1, the lithium secondary battery is a positive electrode active material for a lithium secondary battery, wherein the lithium secondary battery is an all-solid-state battery. Claim 16 In claim 15, the all-solid-state battery is a sulfide-based all-solid-state battery, a positive electrode active material for a lithium secondary battery. Claim 17 A method for manufacturing a positive electrode active material for a lithium secondary battery, comprising: a step of preparing lithium transition metal oxide particles; a step of preparing a precursor mixture in a solution by adding a lithium (Li) precursor, a tantalum (Ta) precursor, and a zinc (Zn) precursor to a solvent and stirring; a step of coating the lithium transition metal oxide particles with the precursor mixture; and a step of heat-treating the lithium transition metal oxide particles coated with the precursor mixture under an oxygen atmosphere; wherein the coating step is performed by introducing the lithium transition metal oxide particles into the precursor mixture in the solution, stirring, and drying to remove the solvent contained in the precursor mixture, and the coating layer formed by the coating step comprises zinc oxide particles and lithium tantalum oxide particles. Claim 18 A method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the lithium (Li) precursor is an oxide containing lithium, the tantalum (Ta) precursor is an oxide containing tantalum, and the zinc (Zn) precursor is an oxide, ammonium salt, or acetate containing zinc. Claim 19 delete Claim 20 A method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the precursor mixture comprises the precursors such that the molar ratio of lithium (Li): tantalum (Ta): zinc (Zn) is 3:1:

1. Claim 21 A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein, in claim 17, the heat treatment is performed at a temperature of 300 ℃ to 1000 ℃. Claim 22 A method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 17, wherein the positive electrode active material for a lithium secondary battery manufactured by the above manufacturing method comprises lithium transition metal oxide particles and a coating layer located on said lithium transition metal oxide particles, and said coating layer comprises zinc oxide particles and lithium tantalum oxide particles. Claim 23 A lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, comprising a positive electrode active material according to claim 1. Claim 24 In claim 23, the above electrolyte is a sulfide-based solid electrolyte, a lithium secondary battery. Claim 25 A lithium secondary battery according to claim 24, wherein the sulfide-based solid electrolyte comprises one or more 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.

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