Composite positive electrode active material, positive electrode and lithium battery using the same, and method for manufacturing the same

Abstract

a core comprising a lithium transition metal oxide; and a shell disposed along a surface of the core; the shell having a chemical formula M a O b (0

Description

Technical Field

[0001] The present invention relates to a composite positive electrode active material, a positive electrode and a lithium battery employing the same, and a method for manufacturing the same.

Background Art

[0002] In order to meet the miniaturization and high performance of various devices, in addition to the miniaturization and weight reduction of lithium batteries, increasing the energy density has become important. That is, high-capacity lithium batteries have become important.

[0003] In order to embody a lithium battery that meets the above applications, a positive electrode active material having a high capacity has been studied.

[0004] Conventional nickel-based positive electrode active materials had a reduced life characteristic due to side reactions and were also inferior in thermal stability.

[0005] Therefore, a method capable of preventing the deterioration of battery performance while including a nickel-based positive electrode active material is required.

Summary of the Invention

Problems to be Solved by the Invention

[0006] One aspect is to provide a new composite positive electrode active material capable of suppressing side reactions of the composite positive electrode active material, improving the reversibility of the electrode reaction, and preventing the deterioration of lithium performance.

[0007] Another aspect is to provide a positive electrode including the composite positive electrode active material.

[0008] Still another aspect is to provide a lithium battery employing the positive electrode.

[0009] Still another aspect is to provide a method for manufacturing the composite positive electrode active material.

Means for Solving the Problems

[0010] On one side, a core containing a lithium transition metal oxide; and a shell disposed along the surface of the core; and the shell contains one or more first metal oxides represented by the chemical formula M a O b (0 < a ≤ 3, 0 < b < 4, if a is 1, 2, or 3, then b is not an integer); a carbon-based material; and a doped phosphorus (P) element; the first metal oxide is disposed within a carbon-based material matrix, and M is one or more metals selected from Groups 2 to 13, 15, and 16 of the periodic table of the elements, and a composite cathode active material is provided.

[0011] On another side, a cathode containing the composite cathode active material is provided.

[0012] On still another side, a lithium battery containing the cathode is provided.

[0013] On still another side, providing a lithium transition metal oxide; providing a composite; and mechanically milling the lithium transition metal oxide and the composite; and the composite contains one or more first metal oxides represented by the chemical formula M a O b (0 < a ≤ 3, 0 < b < 4, if a is 1, 2, or 3, then b is not an integer); a carbon-based material; and a doped phosphorus (P) element; the first metal oxide is disposed within a carbon-based material matrix, and M is one or more metals selected from Groups 2 to 13, 15, and 16 of the periodic table of the elements, and a method for manufacturing a composite cathode active material is provided.

Advantages of the Invention

[0014] According to one aspect, the composite cathode active material includes a first metal oxide, a carbon-based material, and a shell containing a doped phosphorus (P) element, thereby improving the high-temperature cycle characteristics of the lithium battery and suppressing an increase in internal resistance.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0016] The present inventive concept described below can be subject to various transformations and can have various embodiments. Specific embodiments are illustrated in the drawings and will be described in detail by detailed description. However, this is not intended to limit the present inventive concept to specific embodiments, and it should be understood to include all transformations, equivalents, or alternatives included in the technical scope of the present inventive concept.

[0017] The terms used below are only used to describe specific embodiments and are not intended to limit the present inventive concept. Singular expressions include plural expressions as well, unless the context clearly indicates a different meaning. Hereinafter, terms such as “including” or “having” indicate the presence of features, numbers, steps, operations, components, parts, components, materials, or combinations thereof described in the specification, and it should be understood that the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, components, materials, or combinations thereof is not precluded in advance. The “ / ” used below is interpreted as “and” or “or” depending on the situation.

[0018] For the purpose of clearly showing multiple layers and regions in the drawings, the thickness is enlarged or reduced. The same reference numerals are given to similar parts throughout the specification. When parts such as layers, films, regions, plates, etc. are "on" or "above" other parts throughout the specification, it includes not only the case where they are directly above other parts but also the case where there are other parts in between. Throughout the specification, terms such as first, second, etc. can be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

[0019] Hereinafter, a composite positive electrode active material according to an exemplary embodiment, a positive electrode including the same, a lithium battery, and a method for manufacturing the same will be described in more detail.

[0020] The composite positive electrode active material includes a core containing a lithium transition metal oxide; and a shell disposed along the surface of the core, and the shell has the chemical formula M a O b (0 < a ≤ 3, 0 < b < 4, if a is 1, 2, or 3, then b is not an integer) and includes one or more first metal oxides; a carbon-based material; and a doped phosphorus (P) element, the first metal oxide is disposed within a carbon-based material matrix, and M is one or more metals selected from Groups 2 to 13, 15, and 16 of the Periodic Table of the Elements.

[0021] Hereinafter, the theoretical basis for the composite positive electrode active material according to an exemplary embodiment providing excellent effects will be described. This is for the purpose of assisting in the understanding related to the inventive concept and is not intended to limit the inventive concept in any way.

[0022] A shell containing a first metal oxide, a carbon-based material, and a phosphorus (P) element is disposed on the core of the composite positive electrode active material. The phosphorus (P) element contained in the shell is the phosphorus (P) element doped into the shell. The phosphorus (P) element doped into the shell forms a chemical bond with the carbon-based material and / or the first metal oxide contained in the shell. The phosphorus (P) element doped into the shell is distinguished from the phosphorus (P) element physically disposed around the composite positive electrode active material. The phosphorus (P) element doped into the shell is distinguished, for example, from the phosphorus (P) element disposed around the composite positive electrode active material by mixing the composite positive electrode active material with a phosphorus (P)-containing compound or a composition containing the same (e.g., a binder, a conductive material, an electrolyte, etc.). A phosphorus (P) atom has a larger atomic radius and a lower electronegativity than a carbon (C) atom. Therefore, in the shell mainly composed of the carbon-based material which is a carbon-based material, the structural defects of the carbon-based material and the resulting non-uniformity of the charge carrier density can be compensated. For example, by including a phosphorus (P) element in the shell, for example, by adding the electrons of the phosphorus (P) element to the π-electron system of the carbon-based material, the density of the charge carrier increases, and the non-uniformity of the charge carrier density can also be alleviated. Therefore, by including the phosphorus (P) element doped into the shell, the reversibility of the electrode reaction increases on the surface of the composite positive electrode active material, and the internal resistance of the electrode decreases, so that the cycle characteristics of a battery containing such a composite positive electrode active material can be improved.

[0023] Conventional carbon-based materials are prone to aggregation, making it difficult to form a uniform coating on the core. On the other hand, the composite cathode active material uses a composite containing a plurality of first metal oxides disposed in a carbon-based material matrix, so that while preventing the aggregation of the carbon-based materials, a uniform shell is disposed on the core. Therefore, by effectively blocking the contact between the core and the electrolyte, side reactions due to the contact between the core and the electrolyte are prevented. Also, since cation mixing by the electrolyte is suppressed, the formation of a resistance layer is suppressed. Further, the elution of transition metal ions is also suppressed. The carbon-based material is, for example, a crystalline carbon-based material. The carbon-based material is, for example, a carbon-based nanostructure. The carbon-based material is, for example, a carbon-based two-dimensional nanostructure. The carbon-based material is, as an example, graphene. In that case, since the shell containing graphene and / or the matrix has flexibility, the volume change of the composite cathode active material during charge and discharge is easily accommodated, thereby suppressing the generation of cracks inside the composite cathode active material. Since the carbon-based material has high electron transportability, the interfacial resistance between the composite cathode active material and the electrolyte is reduced. Therefore, despite the introduction of the shell containing the carbon-based material, the internal resistance of the lithium battery is maintained or decreased.

[0024] The carbon-based material contained in the shell of the composite cathode active material is derived from a graphene matrix, and thus has a relatively low density and a high porosity compared to conventional carbon-based materials derived from graphite-based materials. The interplanar distance of the carbon-based material contained in the shell of the composite cathode active material is, for example, 3.38 Å or more, 3.40 Å or more, 3.45 Å or more, 3.50 Å or more, 3.60 Å or more, 3.80 Å or more, or 4.00 Å or more. The interplanar distance of the carbon-based material contained in the shell of the composite cathode active material is, for example, 3.38 to 4.0 Å, 3.38 to 3.8 Å, 3.38 to 3.6 Å, 3.38 to 3.5 Å, or 3.38 to 3.45 Å. On the other hand, the interplanar distance of conventional carbon-based materials derived from graphite-based materials is, for example, 3.38 Å or less, or 3.35 to 3.38 Å.

[0025] Since the first metal oxide has voltage resistance, it can prevent the deterioration of the lithium transition metal oxide contained in the core during charge and discharge at high voltage. The shell contains, for example, one type of the first metal oxide or two or more different first metal oxides from each other.

[0026] As a result, an increase in the internal resistance of the lithium battery containing the above-described composite positive electrode active material is suppressed, and the high-temperature and high-voltage cycle characteristics are improved.

[0027] In the composite positive electrode active material, for example, the content of the shell is 0.5 wt% to 3 wt%, 0.5 wt% to 2.5 wt%, 0.5 wt% to 2 wt%, or 0.5 wt% to 1.5 wt% of the total weight of the composite positive electrode active material. Further, the content of the first metal oxide is, for example, also 0.3 wt% to 1.8 wt%, 0.3 wt% to 1.5 wt%, 0.3 wt% to 1.2 wt%, or 0.3 wt% to 0.9 wt% of the total weight of the composite positive electrode active material. By the composite positive electrode active material containing the shell and the first metal oxide in such content ranges, respectively, the cycle characteristics of the lithium battery are further improved.

[0028] The content of the doped phosphorus (P) element contained in the shell is, for example, more than 0 and 5 at%, 0.01 to 4 at%, 0.1 to 3 at%, 0.1 to 2 at%, 0.1 to 1.5 at%, or 0.3 to 1 at% with respect to the total number of atoms of the shell. By the shell being doped with the phosphorus (P) element having such a content range, the cycle characteristics of the lithium battery containing the composite positive electrode active material are further improved. The content of the doped phosphorus (P) element contained in the shell can be obtained, for example, from the peak obtained by measuring the XPS spectrum with respect to the surface of the composite positive electrode active material.

[0029] The content of the first metal contained in the shell is, for example, more than 0 and up to 10 at%, 0.1 to 9.5 at%, 1 to 9 at%, 2 to 9 at%, 3 to 9 at%, 3 to 8 at%, or 4 to 8 at% with respect to the total number of atoms in the shell. By including the first metal having such a content range in the shell, the cycle characteristics of a lithium battery containing the composite positive electrode active material are further improved. The content of the first metal element contained in the shell can be determined, for example, from the peaks obtained by measuring the XPS spectrum with respect to the surface of the composite positive electrode active material.

[0030] The content of carbon contained in the shell is, for example, 80 to 99 at%, 80 to 95 at%, 80 to 93 at%, 80 to 91 at%, or 83 to 90 at% with respect to the total number of atoms in the shell. By including carbon having such a content range in the shell, the cycle characteristics of a lithium battery containing the composite positive electrode active material are further improved. The content of carbon contained in the shell can be determined, for example, from the peaks obtained by measuring the XPS spectrum with respect to the surface of the composite positive electrode active material.

[0031] The metal contained in the first metal oxide is, for example, also one or more selected from among Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se. The first metal oxide is, for example, Al2O z (0 < z < 3), NbO x (0 < x < 2.5), MgO x (0 < x < 1), Sc2O z (0 < z < 3), TiO y (0 < y < 2), ZrO y (0 < y < 2), V2O z (0 < z < 3), WO y (0 < y < 2), MnO y (0 < y < 2), Fe2O z (0 < z < 3), Co3O w (0 < w < 4), PdO x (0 < x < 1), CuO x (0 < x < 1), AgO x (0 < x < 1), ZnO x (0 < x < 1), Sb2O z (0 < z < 3), and SeOy It is also one or more selected from (0 < y < 2). By disposing such a first metal oxide in the carbon-based material matrix, the uniformity of the shell disposed on the core is improved, and the withstand voltage property of the composite cathode active material is further improved. For example, the shell is Al2O as the first metal oxide x includes (0 < x < 3).

[0032] The shell has the chemical formula M a O c (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer) and further includes one or more second metal oxides represented by. The M is one or more metals selected from Groups 2 to 13, 15, and 16 of the periodic table of the elements. For example, the second metal oxide contains the same metal as the first metal oxide, and the ratio c / a of a and c of the second metal oxide has a value further larger than the ratio b / a of a and b of the first metal oxide. For example, c / a > b / a. The second metal oxide is, for example, selected from Al2O3, NbO, NbO2, Nb2O5, MgO, Sc2O3, TiO2, ZrO2, V2O3, WO2, MnO2, Fe2O3, Co3O4, PdO, CuO, AgO, ZnO, Sb2O3, and SeO2. The first metal oxide is a reduction product of the second metal oxide. By reducing some or all of the second metal oxide, the first metal oxide is obtained. Therefore, the first metal oxide has a lower oxygen content and a higher oxidation number of the metal than the second metal oxide. For example, the shell is Al2O as the first metal oxide x (0 < x < 3) and Al2O3 as the second metal oxide.

[0033] In the composite positive electrode active material, for example, the transition metal of the carbon-based material contained in the shell and the transition metal of the lithium transition metal oxide contained in the core are chemically bonded through a chemical bond. The carbon atom (C) of the carbon-based material contained in the shell and the transition metal (Me) of the lithium transition metal oxide are chemically bonded through, for example, an oxygen atom via a C-O-Me bond (for example, a C-O-Ni bond or a C-O-Co bond). By chemically bonding the carbon-based material contained in the shell and the lithium transition metal oxide contained in the core through a chemical bond, the core and the shell are complexed. Therefore, it is distinguished from a mere physical mixture of the carbon-based material and the lithium transition metal oxide.

[0034] Also, the first metal oxide contained in the shell and the carbon-based material are also chemically bonded through a chemical bond. Here, the chemical bond is, for example, a covalent bond or an ionic bond. The covalent bond is, for example, a bond containing at least one of an ester group, an ether group, a carbonyl group, an amide group, a carbonate anhydride group, and an acid anhydride group. The ionic bond is, for example, a bond containing a carboxylic acid ion, an ammonium ion, an acyl cation group, and the like.

[0035] The thickness of the shell is, for example, 1 nm to 5 μm, 1 nm to 1 μm, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 90 nm, 1 nm to 80 nm, 1 nm to 70 nm, 1 nm to 60 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 20 nm. By having such a range of thickness, an increase in the internal resistance of the lithium battery containing the composite positive electrode active material is suppressed.

[0036] In the composite positive electrode active material, for example, it further includes a third metal doped on the core or a third metal oxide coated on the core. And the shell can be disposed on the doped third metal or the coated third metal oxide. For example, the third metal can be doped on the surface of the lithium transition metal oxide included in the core, or after the third metal oxide is coated on the surface of the lithium transition metal oxide, it can be disposed on the third metal and / or the third metal oxide as the shell. For example, the composite positive electrode active material includes a core; an intermediate layer disposed on the core; and a shell disposed on the intermediate layer, and the intermediate layer includes a third metal or a third metal oxide. The third metal is one or more metals selected from Al, Zr, W, and Co, and the third metal oxide is also Al2O3, Li2O-ZrO2, WO2, CoO, Co2O3, Co3O4, etc.

[0037] The shell included in the composite positive electrode active material includes, for example, one or more selected from a first metal oxide, a carbon-based material, for example, a composite including graphene and a doped phosphorus (P) element, and a milling product of the composite, and the first metal oxide is disposed in a matrix of the carbon-based material, for example, a graphene matrix. The shell is, for example, manufactured from a first metal oxide, a carbon-based material, for example, a composite including graphene and a doped phosphorus (P) element. The composite may further include a second metal oxide in addition to the first metal oxide. The composite includes, for example, two or more kinds of first metal oxides. The composite includes, for example, two or more kinds of first metal oxides and two or more kinds of second metal oxides.

[0038] The content of the doped phosphorus (P) element contained in the composite is, for example, more than 0 and 5 at% or less, 0.01 to 4 at%, 0.1 to 3 at%, 0.1 to 2 at%, 0.1 to 1.5 at%, or 0.3 to 1 at% with respect to the total number of atoms of the composite. By doping the composite with a phosphorus (P) element having such a content range, the cycle characteristics of a lithium battery employing a composite cathode active material having a shell containing the composite and / or its milling product can be further improved. The content of the doped phosphorus (P) element contained in the composite can be determined, for example, from the peak obtained by measuring the XPS spectrum with respect to the surface of the composite or the surface of the composite cathode active material coated with the composite.

[0039] The content of one or more of the composite and its milling product contained in the composite cathode active material is also 3 wt% or less, 2 wt% or less, 1 wt% or less, 0.5 wt% or less, 0.2 wt% or less of the total weight of the composite cathode active material. The content of one or more of the composite and its milling product is also 0.01 wt% to 3 wt%, 0.01 wt% to 1 wt%, 0.01 wt% to 0.7 wt%, 0.01 wt% to 0.5 wt%, 0.01 wt% to 0.2 wt%, 0.01 wt% to 0.1 wt%, or 0.03 wt% to 0.07 wt% of the total weight of the composite cathode active material. By the composite cathode active material containing one or more of the composite and its milling product within such a range, the cycle characteristics of the lithium battery containing the composite cathode active material are further improved.

[0040] One or more average particle sizes selected from the first metal oxide and the second metal oxide included in the composite are 1 nm to 1 μm, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 70 nm, 1 nm to 50 nm, 1 nm to 30 nm, 3 nm to 30 nm, 3 nm to 25 nm, 5 nm to 25 nm, 5 nm to 20 nm, or 7 nm to 20 nm. By the first metal oxide and / or the second metal oxide having such a nano-scale particle size, it can be more uniformly distributed within the carbon-based material matrix of the composite. Therefore, such a composite can be uniformly coated on the core without aggregation to form a shell. Also, by the first metal oxide and / or the second metal oxide having such a range of particle sizes, it can be more uniformly arranged on the core. Therefore, by the first metal oxide and / or the second metal oxide being uniformly arranged on the core, the withstand voltage characteristics can be more effectively exhibited.

[0041] The average particle sizes of the first metal oxide and the second metal oxide are measured, for example, using a measuring device of a laser diffraction method or a dynamic light scattering method. The average particle size is, for example, measured using a laser scattering particle size distribution meter (for example, LA-920 manufactured by Horiba, Ltd.), and is the value of the median particle size (D50) when accumulated 50% from the primary particle side in terms of volume.

[0042] The uniformity deviation of one or more selected from the first metal oxide and the second metal oxide included in the composite is also 3% or less, 2% or less, or 1% or less. The uniformity can be determined, for example, by XPS. Therefore, one or more selected from the first metal oxide and the second metal oxide in the composite can be uniformly distributed while having a deviation of 3% or less, 2% or less, or 1% or less.

[0043] The carbon-based material included in the composite may have, for example, a branched structure, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the branched structure of the carbon-based material. The branched structure of the carbon-based material includes, for example, a plurality of carbon-based material particles in contact with each other. By having a branched structure, the carbon-based material can provide various conductive paths.

[0044] The carbon-based material included in the composite may also be, for example, graphene. The graphene may have, for example, a branched structure, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the branched structure of the graphene. The branched structure of the graphene includes, for example, a plurality of graphene particles in contact with each other. By having a branched structure, the graphene can provide various conductive paths.

[0045] The carbon-based material included in the composite may have, for example, a spherical structure, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the spherical structure. The size of the spherical structure of the carbon-based material is also 50 nm to 300 nm. There are also a plurality of carbon-based materials having a spherical structure. By having a spherical structure, the composite can have a firm structure.

[0046] The carbon-based material included in the composite may also be, for example, graphene. The graphene may have, for example, a spherical structure, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the spherical structure. The size of the spherical structure of the graphene is also 50 nm to 300 nm. There are also a plurality of graphene having a spherical structure. By having a spherical structure, the composite can have a firm structure.

[0047] The carbon-based material contained in the composite has, for example, a spiral structure in which a plurality of spherical structures are connected, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the spherical structure of the spiral structure. The size of the spiral structure of the carbon-based material is also 500 nm to 100 μm. Since the carbon-based material has a spiral structure, the composite can have a firm structure.

[0048] The carbon-based material contained in the composite is, for example, also graphene. The graphene has, for example, a spiral structure in which a plurality of spherical structures are connected, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the spherical structure of the spiral structure. The size of the spiral structure of the graphene is also 500 nm to 100 μm. Since the graphene has a spiral structure, the composite can have a firm structure.

[0049] The carbon-based material contained in the composite has, for example, a cluster structure in which a plurality of spherical structures are aggregated, and one or more metal oxides selected from among the first metal oxide and the second metal oxide may be distributed within the spherical structure of the cluster structure. The size of the cluster structure of the carbon-based material is also 0.5 mm to 10 cm. Since the carbon-based material has a cluster structure, the composite can have a firm structure.

[0050] The carbon-based material included in the composite is also, for example, graphene. The graphene has, for example, a cluster structure in which a plurality of spherical structures are aggregated, and one or more metal oxides selected from among the first metal oxide and the second metal oxide can be distributed within the spherical structure of the cluster structure. The size of the cluster structure of graphene is also 0.5 mm to 10 cm. Since the graphene has a cluster structure, the composite can have a firm structure.

[0051] The composite is, for example, a faceted-ball structure, and one or more selected from among the first metal oxide and the second metal oxide can be distributed inside or on the surface of the structure. The composite can be easily coated on the irregular surface unevenness of the core by such a polyhedral ball structure.

[0052] The composite is, for example, a planar structure, and one or more selected from among the first metal oxide and the second metal oxide can be distributed inside or on the surface of the structure. The composite can be easily coated on the irregular surface unevenness of the core by such a two-dimensional planar structure.

[0053] The carbon-based material included in the composite extends, for example, a distance of 10 nm or less with the first metal oxide and includes at least 1 to 20 carbon-based material layers. For example, by laminating a plurality of carbon-based material layers, a carbon-based material having a total thickness of 12 nm or less can be disposed on the first metal oxide. For example, the total thickness of the carbon-based material is also 0.6 to 12 nm.

[0054] The carbon-based material included in the composite is also, for example, graphene. The graphene extends, for example, a distance of 10 nm or less with the first metal oxide and includes at least 1 to 20 graphene layers. For example, by laminating a plurality of graphene layers, graphene having a total thickness of 12 nm or less can be disposed on the first metal oxide. For example, the total thickness of the graphene is also 0.6 to 12 nm.

[0055] The core contained in the composite positive electrode active material contains, for example, a lithium transition metal oxide represented by the following Chemical Formula 1: <Chemical Formula 1> Li a Co x M y O 2-b A b In the Chemical Formula 1, 1.0 ≦ a ≦ 1.2, 0 ≦ b ≦ 0.2, 0.9 ≦ x ≦ 1, 0 ≦ y ≦ 0.1, and x + y = 1, M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof, and A is F, S, Cl, Br or a combination thereof.

[0056] The core contained in the composite positive electrode active material contains, for example, a lithium transition metal oxide represented by the following Chemical Formulas 2 to 4: <Chemical Formula 2> LiNi x Co y Mn z O2 <Chemical Formula 3> LiNi x Co y Al z O2 In the Chemical Formulas 2 and 3, 0.8 ≦ x ≦ 0.95, 0 < y ≦ 0.2, 0 < z ≦ 0.2 and x + y + z = 1. <Chemical Formula 4> LiNi x Co y Mn v Al w O2 In the Chemical Formula 4, 0.8 ≦ x ≦ 0.95, 0 < y ≦ 0.2, 0 < v ≦ 0.2, 0 < w ≦ 0.2, and x + y + v + w = 1.

[0057] The lithium transition metal oxides of Chemical Formulas 1 to 4 provide excellent initial capacity, normal temperature life characteristics, and high temperature life characteristics while having a high nickel content of 80 mol% or more, 85 mol% or more, or 90 mol% or more based on the total number of moles of transition metals.

[0058] For example, in the lithium transition metal oxides of Chemical Formulas 1 to 4, the nickel content is also 80 mol% to 95 mol%, 85 mol% to 95 mol%, or 90 mol% to 95 mol% based on the total number of moles of transition metals.

[0059] The core included in the composite cathode active material includes, for example, a lithium transition metal oxide represented by the following Chemical Formulas 5 to 6: <Chem. 5> Li a Co x M y O 2-b A b In the above Chemical Formula 5, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, and x + y = 1, M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof, and A is F, S, Cl, Br, or a combination thereof. <Chem. 6> LiCoO2

[0060] According to another embodiment, the cathode includes the above-described composite cathode active material. By including the above-described composite cathode active material in the cathode, improved cycle characteristics and reduced internal resistance are provided.

[0061] The cathode is manufactured, for example, by the following exemplary method, but is not necessarily limited to such a method and is adjusted according to the required conditions.

[0062] First, a positive electrode active material composition is prepared by mixing the above-described composite positive electrode active material, conductive material, binder, and solvent. The prepared positive electrode active material composition is directly coated and dried on an aluminum current collector to produce a positive electrode plate having a positive electrode active material layer formed thereon. Alternatively, after casting the positive electrode active material composition on a separate support, the film obtained by peeling it from the support is laminated on the aluminum current collector to produce a positive electrode plate having a positive electrode active material layer formed thereon.

[0063] As the conductive material, carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon fiber; carbon nanotube; metal powders such as copper, nickel, aluminum, silver, or metal fibers or metal tubes; conductive polymers such as polyphenylene derivatives are used, but are not limited thereto, and any material that can be used as a conductive material in the technical field can be used.

[0064] As the binder, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), a mixture of the above-described polymers, styrene-butadiene rubber-based polymers, etc. are used, and as the solvent, N-methylpyrrolidone (NMP), acetone, water, etc. are used, but are not necessarily limited thereto, and any material that can be used in the technical field can be used.

[0065] It is also possible to further add a plasticizer or a pore former to the positive electrode active material composition to form pores inside the electrode plate.

[0066] The contents of the composite positive electrode active material, conductive material, binder, and solvent used in the positive electrode are at levels commonly used in lithium batteries. Depending on the use and configuration of the lithium battery, one or more of the conductive material, binder, and solvent can be omitted.

[0067] The binder content included in the positive electrode is also 0.1 to 10 wt% or 0.1 to 5 wt% of the total weight of the positive electrode active material layer. The composite positive electrode active material content included in the positive electrode is also 90 wt% to 99 wt% or 95 wt% to 99 wt% of the total weight of the positive electrode active material layer.

[0068] In addition, the positive electrode can further include other common positive electrode active materials in addition to the above-mentioned composite positive electrode active material.

[0069] Common positive electrode active materials are lithium-containing metal oxides, and any of them can be used without limitation as long as they are commonly used in the technical field. For example, one or more of composite oxides of metals selected from cobalt, manganese, nickel, and combinations thereof and lithium can be used, and specific examples thereof include Li a A 1-b B b D2 (in the above formula, 0.90 ≦ a ≦ 1 and 0 ≦ b ≦ 0.5); Li a E 1-b B b O 2-c D c (in the above formula, 0.90 ≦ a ≦ 1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); LiE 2-b B b O 4-c D c (in the above formula, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); Li a Ni 1-b-c Co b B c D α (in the above formula, 0.90 ≦ a ≦ 1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 < α ≦ 2); Li a Ni 1-b-c Co b B c O 2-α F α (in the above formula, 0.90 ≦ a ≦ 1, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-αF2 (in the formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α (in the formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α F α (in the formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α F2 (in the formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2 (in the formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2 (in the formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (in the formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (in the formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3 (0 ≤ f ≤ 2); Li(3-f) A compound represented by any one of the chemical formulas Fe2(PO4)3 (0 ≦ f ≦ 2); LiFePO4 can be used.

[0070] In the chemical formula representing the above-mentioned compound, A is Ni, Co, Mn, or a combination thereof; B 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; F 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; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0071] It is also possible to use a compound with a coating layer added to the surface of the above-mentioned compound, and it is also possible to use a mixture of the above-mentioned compound and a compound with a coating layer added. The coating layer added to the surface of the above-mentioned compound includes, for example, a coating element compound such as an oxide of the coating element, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element. The compound forming such a coating layer is amorphous or crystalline. The coating element contained in the coating layer is Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. Coating methods include, for example, spray coating, dipping method, etc. Specific coating methods are well understood by those skilled in the art, so detailed description is omitted.

[0072] Furthermore, a lithium battery according to another embodiment employs a positive electrode containing the above-mentioned composite positive electrode active material.

[0073] By adopting a positive electrode containing the above-described composite positive electrode active material in a lithium battery, improved cycle characteristics and thermal stability are provided.

[0074] The lithium battery is manufactured, for example, by the following exemplary method, but is not necessarily limited to such a method and is adjusted according to the required conditions.

[0075] First, a positive electrode is manufactured by the above-described positive electrode manufacturing method.

[0076] Next, a negative electrode is manufactured as follows. The negative electrode is manufactured by substantially the same method as the positive electrode, except that, for example, a negative electrode active material is used instead of the composite positive electrode active material. Also, in the negative electrode active material composition, the conductive material, binder, and solvent can be substantially the same as those of the positive electrode.

[0077] For example, a negative electrode active material composition is manufactured by mixing a negative electrode active material, a conductive material, a binder, and a solvent, and the negative electrode plate is manufactured by directly coating it on a copper current collector. Alternatively, the manufactured negative electrode active material composition is cast on a separate support, and the negative electrode active material film peeled off from the support is laminated on a copper current collector to manufacture a negative electrode plate.

[0078] Any negative electrode active material can be used as long as it is used as a negative electrode active material for a lithium battery in the relevant technical field. For example, it contains one or more selected from the group consisting of lithium metal, a metal alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials.

[0079] Metals that can form alloys with lithium include, for example, Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloys (where Y is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combination thereof and is not Si), Sn-Y alloys (where Y is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combination thereof and is not Sn), and the like. The element Y is, for example, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0080] The transition metal oxides are, for example, lithium titanate, vanadium oxide, lithium vanadate, and the like.

[0081] Non-transition metal oxides are, for example, SnO2, SiO x (0 < x < 2), and the like.

[0082] Carbon-based materials are, for example, crystalline carbon, amorphous carbon, or a mixture thereof. Crystalline carbon is, for example, graphite such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite. Amorphous carbon is, for example, soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0083] The contents of the negative electrode active material, conductive material, binder, and solvent are at levels commonly used in lithium batteries. Depending on the use and configuration of the lithium battery, one or more of the conductive material, binder, and solvent can be omitted.

[0084] The binder content contained in the negative electrode is, for example, also 0.1 to 10 wt% or 0.1 to 5 wt% of the total weight of the negative electrode active material layer. The conductive material content contained in the negative electrode is, for example, also 0.1 to 10 wt% or 0.1 to 5 wt% of the total weight of the negative electrode active material layer. The negative electrode active material content contained in the negative electrode is, for example, also 90 wt% to 99 wt% or 95 wt% to 99 wt% of the total weight of the negative electrode active material layer. When the negative electrode active material is lithium metal, the negative electrode does not contain a binder and a conductive material.

[0085] Next, a separator inserted between the positive electrode and the negative electrode is provided.

[0086] Any separator can be used as long as it is commonly used in lithium batteries. For example, a separator with low resistance to the ion movement of the electrolyte and excellent electrolyte moisture retention ability is used. The separator is, for example, selected from among glass fiber, polyester, Teflon (registered trademark), polyethylene, polypropylene, polytetrafluoroethylene (PTFE) or a combination thereof, and is in the form of a non-woven fabric or a woven fabric. For lithium-ion batteries, a wound separator such as polyethylene or polypropylene is used, and for lithium-ion polymer batteries, a separator with excellent impregnation ability for organic electrolytes is used.

[0087] The separator is manufactured by the following exemplary methods, but is not necessarily limited to such methods and is adjusted according to the required conditions.

[0088] First, a polymer resin, a filler and a solvent are mixed to prepare a separator composition. The separator composition is directly coated and dried on the upper part of the electrode to form a separator. Alternatively, after the separator composition is cast and dried on a support, the separator film peeled from the support is laminated on the upper part of the electrode to form a separator.

[0089] The polymer used in separator manufacturing is not particularly limited, and any polymer that can be used as a binder for electrode plates can be used. For example, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or a mixture thereof is used.

[0090] Next, an electrolyte is prepared.

[0091] The electrolyte is, for example, an organic electrolyte solution. The organic electrolyte solution is produced by dissolving a lithium salt in an organic solvent, for example.

[0092] Any organic solvent can be used as long as it is used as an organic solvent in the relevant technical field. Examples of the organic solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0093] Any lithium salt can be used as long as it is used as a lithium salt in the relevant technical field. Examples of the lithium salt include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1(SO2) (where x and y are natural numbers from 1 to 20), LiCl, LiI, or a mixture thereof, etc.

[0094] Alternatively, the electrolyte is a solid electrolyte. The solid electrolyte is, for example, boron oxide, lithium oxynitride, etc., but is not limited thereto, and any solid electrolyte that can be used in the technical field can be used. The solid electrolyte is formed on the negative electrode by a method such as sputtering, for example, or a separate solid electrolyte sheet is laminated on the negative electrode.

[0095] The solid electrolyte is, for example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte.

[0096] The solid electrolyte is, for example, an oxide-based solid electrolyte. The oxide-based solid electrolyte is Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 < x < 2, 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (0 ≤ x < 1, 0 ≤ y < 1), PB(Mg3Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3 (0 < x < 2, 0 < y < 3), Li x Al y Ti z (PO4)3 (0 < x < 2, 0 < y < 1, 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 10 ≤ y ≤ 1), Li x La yTiO3 (0 < x < 2, 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, x is an integer from 1 to 10) is one or more selected therefrom. The solid electrolyte is produced by a method such as a sintering method. For example, the oxide-based solid electrolyte is Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M doped LLZO, M = Ga, W, Nb, Ta, or Al, x is an integer from 1 to 10) is a garnet-type solid electrolyte selected therefrom.

[0097] The sulfide-based solid electrolyte includes, for example, lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or a combination thereof. The sulfide-based solid electrolyte particles include Li2S, P2S5, SiS2, GeS2, B2S3, or a combination thereof. The sulfide-based solid electrolyte particles are also Li2S or P2S5. The sulfide-based solid electrolyte particles are known to have a high lithium ion conductivity compared to other inorganic compounds. For example, the sulfide-based solid electrolyte includes Li2S and P2S5. When the sulfide solid electrolyte material constituting the sulfide-based solid electrolyte contains Li2S - P2S5, the mixed molar ratio of Li2S:P2S5 is also, for example, in the range of about 50:50 to about 90:10. Also, Li3PO4, halogen, halogen compound, Li 2+2x Zn 1-x GeO4 (“LISICON”, 0 ≤ x < 1), Li 3+y PO 4-x N x( “LIPON”, 0 < x < 4, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 S4 (“ThioLISICON”), Li2O - Al2O3 - TiO2 - P2O 5(Inorganic solid electrolytes produced by adding (such as "LATP") to inorganic solid electrolytes of Li2S-P2S5, SiS2, GeS2, B2S3, or combinations thereof can be used as sulfide solid electrolytes. Non-limiting examples of sulfide solid electrolyte materials include Li2S-P2S5; Li2S-P2S5-LiX (X = halogen element); Li2S-P2S5-Li2O; Li2S-P2S5-Li2O-LiI; Li2S-SiS2; Li2S-SiS2-LiI; Li2S-SiS2-LiBr; Li2S-SiS2-LiCl; Li2S-SiS2-B2S3-LiI; Li2S-SiS2-P2S5-LiI; Li2S-B2S3; Li2S-P2S5-Z m S n (0 < m < 10, 0 < n < 10, Z = Ge, Zn or Ga); Li2S-GeS2; Li2S-SiS2-Li3PO4; and Li2S-SiS2-Li p MO q (0 < p < 10, 0 < q < 10, M = P, Si, Ge, B, Al, Ga or In). In this connection, sulfide-based solid electrolyte materials can be produced by treating raw starting materials of sulfide-based solid electrolyte substances (such as Li2S, P2S5, etc.) by the melt quenching method, mechanical milling method, etc. Also, a calcination process can be carried out after the said treatment. Sulfide-based solid electrolytes can be amorphous, crystalline, or in a state where they are mixed.

[0098] As shown in FIG. 2, an exemplary lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The positive electrode 3, the negative electrode 2, and the separator 4 are wound or folded and housed in a battery case 5. An organic electrolyte solution is injected into the battery case 5 and sealed by a cap assembly 6 to complete the lithium battery 1. The battery case 5 is cylindrical, but is not necessarily limited to such a form, and can be, for example, square, thin film-like, etc.

[0099] The pouch-type lithium battery includes one or more battery structures. A separator is disposed between the positive electrode and the negative electrode to form a battery structure. After the battery structures are stacked by a bicell structure, they are impregnated with an organic electrolyte solution, housed and sealed in a pouch, and thus the pouch-type lithium battery is completed.

[0100] A plurality of lithium batteries are stacked to form a battery module and / or a battery pack, and such a battery module and / or a battery pack is used in any device that requires high capacity and high output. For example, it can be used in a notebook computer, a smartphone, an electric vehicle, etc.

[0101] A lithium battery using a solid electrolyte is also a solid battery or an all-solid battery. A lithium battery using a solid electrolyte may further include a solid electrolyte in one or more of the positive electrode and the negative electrode. For example, in a lithium battery in which an electrolyte layer containing a sulfide-based solid electrolyte is disposed between the positive electrode and the negative electrode, one or more of the positive electrode and the negative electrode contain a sulfide-based solid electrolyte.

[0102] Since lithium batteries are excellent in life characteristics and high-rate characteristics, they are used, for example, in electric vehicles (EV), energy storage systems (ESS), etc. For example, they are used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). They are also used in fields where a large amount of power storage is required. For example, they are used in electric bicycles, electric tools, etc.

[0103] Furthermore, a method for manufacturing a composite positive electrode active material according to another embodiment includes: providing a lithium transition metal oxide; providing a composite; and mechanically milling the lithium transition metal oxide and the composite, wherein the composite has the chemical formula M a O b(0 < a ≤ 3, 0 < b < 4, where a is 1, 2, or 3 and b is not an integer) one or more first metal oxides; a carbon-based material; and a doped phosphorus (P) element, wherein the first metal oxide is disposed within the carbon-based material matrix, and said M is one or more metals selected from Groups 2 to 13, 15, and 16 of the Periodic Table of the Elements. In the step of mechanical milling, the milling method is not particularly limited and is a method of bringing a lithium transition metal oxide into contact with a composite using a machine, and any method that can be used in the art can be used.

[0104] A lithium transition metal oxide is provided. The lithium transition metal oxide is, for example, a compound represented by Chemical Formulas 1 to 6 described above.

[0105] The step of providing the composite includes, for example: supplying a reaction gas composed of a carbon source gas to a structure containing a metal oxide and performing heat treatment to provide an undoped composite; and mixing the undoped composite with a phosphorus (P)-containing compound and performing heat treatment to prepare the composite.

[0106] The step of providing the composite includes, for example, M a O c (0 < a ≤ 3, 0 < c ≤ 4, when a is 1, 2, or 3, b is an integer) one or more second metal oxides, supplying a reaction gas composed of a carbon source gas thereto, and performing heat treatment to produce an undoped composite, wherein said M is one or more metals selected from Groups 2 to 13, 15, and 16 of the Periodic Table of the Elements.

[0107] The carbon source gas is a compound represented by the following Chemical Formula 7, or a mixed gas of one or more selected from the group consisting of a compound represented by the following Chemical Formula 7, a compound represented by the following Chemical Formula 8, and an oxygen-containing gas represented by the following Chemical Formula 9.

[0108] <Chemical Formula 7> CnH (2n+2-a) [OH] a In the above chemical formula 7, n is from 1 to 20, and a is 0 or 1; <Chemical formula 8> CnH 2n In the above chemical formula 8, n is from 2 to 6; <Chemical formula 9> C x H y O z In the above chemical formula 9, x is 0 or an integer from 1 to 20, y is 0 or an integer from 1 to 20, and z is 1 or 2.

[0109] The compound represented by chemical formula 7 and the compound represented by chemical formula 8 are one or more selected from the group consisting of methane, ethylene, propylene, methanol, ethanol, and propanol. The oxygen-containing gas represented by chemical formula 9 includes, for example, carbon dioxide (CO2) and carbon monoxide (CO), water vapor (H2O), or a mixture thereof.

[0110] M a O c After supplying a reaction gas composed of a carbon source gas to the second metal oxide represented by (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer) and performing heat treatment, a cooling step using one or more inert gases selected from the group consisting of nitrogen, helium, and argon can be further performed. The cooling step means a step of adjusting to room temperature (20 - 25°C). The carbon source gas may contain one or more inert gases selected from the group consisting of nitrogen, helium, and argon.

[0111] The process of growing a carbon-based material, such as graphene, by a gas-phase reaction in the method for producing the composite can be carried out under various conditions.

[0112] According to the first condition, for example, M a O cTo a reactor in which a second metal oxide represented by (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer) is disposed, methane is first supplied, and the temperature is raised to a heat treatment temperature T. The temperature raising time to the heat treatment temperature T is 10 minutes to 4 hours, and the heat treatment temperature T is in the range of 700 to 1100°C. During the reaction time at the heat treatment temperature T, heat treatment is carried out. The reaction time is, for example, 4 to 8 hours. The heat-treated product is cooled to room temperature to produce a composite. The time taken in the process of cooling from the heat treatment temperature T to room temperature is, for example, 1 to 5 hours.

[0113] According to the second condition, for example, M a O c To a reactor in which a second metal oxide represented by (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer) is disposed, hydrogen is first supplied, and the temperature is raised to a heat treatment temperature T. The temperature raising time to the heat treatment temperature T is 10 minutes to 4 hours, and the heat treatment temperature T is in the range of 700 to 1100°C. After heat treatment for a certain reaction time at the heat treatment temperature T, methane gas is supplied, and heat treatment is carried out during the remaining reaction time. The reaction time is, for example, 4 to 8 hours. The heat-treated product is cooled to room temperature to produce a composite. Nitrogen is supplied during the cooling process. The time taken in the process of cooling from the heat treatment temperature T to room temperature is, for example, 1 to 5 hours.

[0114] According to the third condition, for example, M a O c To a reactor in which a second metal oxide represented by (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer) is disposed, hydrogen is first supplied, and the temperature is raised to a heat treatment temperature T. The temperature raising time to the heat treatment temperature T is 10 minutes to 4 hours, and the heat treatment temperature T is in the range of 700 to 1100°C. After heat treatment for a certain reaction time at the heat treatment temperature T, a mixed gas of methane and hydrogen is supplied, and heat treatment is carried out during the remaining reaction time. The reaction time is, for example, 4 to 8 hours. The heat-treated product is cooled to room temperature to produce a composite. Nitrogen is supplied during the cooling process. The time taken in the process of cooling from the heat treatment temperature T to room temperature is, for example, 1 to 5 hours.

[0115] When producing the composite, if the carbon source gas contains water vapor, a composite with very excellent conductivity can be obtained. The content of water vapor in the gas mixture is not limited. For example, it is 0.01 to 10% by volume based on 100% by volume of the total carbon source gas. The carbon source gas is, for example, methane; a gas mixture containing methane and an inert gas; or a gas mixture containing methane and an oxygen-containing gas.

[0116] The carbon source gas is also, for example, methane; a gas mixture of methane and carbon dioxide; or a gas mixture of methane, carbon dioxide and water vapor. In the gas mixture of methane and carbon dioxide, the molar ratio of methane to carbon dioxide is about 1:0.20 to 1:0.50, about 1:0.25 to 1:0.45, or about 1:0.30 to 1:0.40. In the gas mixture of methane, carbon dioxide and water vapor, the molar ratio of methane, carbon dioxide and water vapor is about 1:0.20 to 0.50:0.01 to 1.45, about 1:0.25 to 0.45:0.10 to 1.35, or about 1:0.30 to 0.40:0.50 to 1.0.

[0117] The carbon source gas is, for example, carbon monoxide or carbon dioxide. The carbon source gas is, for example, a gas mixture of methane and nitrogen. In the gas mixture of methane and nitrogen, the molar ratio of methane to nitrogen is about 1:0.20 to 1:0.50, about 1:0.25 to 1:0.45, about 1:0.30 to 1:0.40. The carbon source gas does not contain an inert gas such as nitrogen.

[0118] The heat treatment pressure can be selected in consideration of the heat treatment temperature, the composition of the gas mixture, and the amount of the desired carbon coating, etc. The heat treatment pressure can be controlled by adjusting the amount of the inflowing gas mixture and the amount of the outflowing gas mixture. The heat treatment pressure is, for example, 0.5 atm or more, 1 atm or more, 2 atm or more, 3 atm or more, 4 atm or more, or 5 atm or more.

[0119] The heat treatment time is not particularly limited and can be appropriately adjusted according to the heat treatment temperature, the pressure during heat treatment, the composition of the gas mixture, and the amount of the desired carbon coating. For example, the reaction time at the heat treatment temperature is, for example, from 10 minutes to 100 hours, from 30 minutes to 90 hours, or from 50 minutes to 40 hours. For example, as the heat treatment time increases, the amount of carbon deposited, for example, the amount of graphene, increases, whereby the electrical properties of the composite can be improved. However, such a tendency is not necessarily directly proportional to the time. For example, after a predetermined time has elapsed, no further carbon deposition, for example, graphene deposition, occurs or the deposition rate decreases.

[0120] Even at a relatively low temperature through the gas-phase reaction of the carbon source gas described above, M a O c (0 < a ≤ 3, 0 < c ≤ 4, if a is 1, 2, or 3, then c is an integer) and the reduced product thereof, M a O b By providing a uniform carbon-based material coating, for example, a graphene coating, on one or more selected from the first metal oxides represented by (0 < a ≤ 3, 0 < b < 4, a is 1, 2, or 3, and b is not an integer), an undoped composite is obtained.

[0121] The undoped composite has, for example, a matrix of a carbon-based material having one or more structures selected from a spherical structure, a spiral structure in which a plurality of spherical structures are connected, a cluster structure in which a plurality of spherical structures are aggregated, and a sponge structure, for example, a graphene matrix, and M disposed within the carbon-based material matrix a O b (0 < a ≤ 3, 0 < b < 4, a is 1, 2, or 3, and b is not an integer) and the first metal oxide and M a O cIt contains one or more selected from among second metal oxides represented by (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer).

[0122] Next, an undoped composite and a phosphorus (P)-containing compound are mixed and heat-treated to prepare a phosphorus (P)-doped composite.

[0123] For example, after mixing an undoped composite and a phosphorus (P)-containing compound in a solvent, the solvent can be removed and heat-treated to prepare a phosphorus (P)-doped composite. By the heat treatment, the phosphorus (P) element contained in the phosphorus (P)-containing compound is doped into the composite.

[0124] The heat treatment can be carried out, for example, in an inert atmosphere. The inert atmosphere is, for example, a nitrogen atmosphere, an argon atmosphere, etc., but is not limited thereto, and any inert atmosphere that can be used in the technical field is possible.

[0125] The heat treatment temperature is not particularly limited as long as the phosphorus (P)-containing compound is thermally decomposed and phosphorus (P) is doped into the composite. The heat treatment temperature is, for example, 700 to 1200 °C, 700 to 1100 °C, 800 to 1100 °C, or 900 to 1100 °C. The heat treatment time is not particularly limited as long as the phosphorus (P)-containing compound is thermally decomposed and phosphorus (P) is doped into the composite. The heat treatment time is, for example, 0.5 hour to 5 hours.

[0126] The phosphorus (P)-containing compound is not particularly limited as long as it is a compound containing a phosphorus (P) atom, and can also be a phosphorus (P)-containing organic compound or a phosphorus (P)-containing inorganic compound.

[0127] The phosphorus (P)-containing compound is, for example, also a compound represented by the following Chemical Formulas 6 and 7:

[0128]

Chemical Formula

[0129] [Chemical]

[0130] In the above formula, X1, X2 and X3 are each independently a covalent bond, O, S or NR4, R1, R2, R3 and R4 are each independently an alkyl group having 1 to 10 carbon atoms which may or may not be substituted with halogen, a cyanoalkyl group having 1 to 10 carbon atoms which may or may not be substituted with halogen, an alkenyl group having 2 to 10 carbon atoms which may or may not be substituted with halogen, an aryl group having 5 to 20 carbon atoms which may or may not be substituted with halogen, a heteroaryl group having 2 to 20 carbon atoms which may or may not be substituted with halogen, or -Si(R5)(R6)(R7), and R5, R6 and R7 are each independently an alkyl group having 1 to 5 carbon atoms which may or may not be substituted with halogen.

[0131] Phosphorus (P)-containing compounds are also, for example, triphenyl phosphine, triphenyl phosphine oxide, triphenyl phosphate, triphenyl phosphite and the like.

[0132] Next, the lithium transition metal oxide and the composite are mechanically milled. A Nobilta mixer or the like can be used during milling. The rotation speed of the mixer during milling is, for example, 1000 rpm to 2500 rpm. If the milling speed is less than 1000 rpm, the shear force applied to the lithium transition metal oxide and the composite is weak, so it is difficult for the lithium transition metal oxide and the composite to form a chemical bond. If the milling speed is excessively high, the complexation proceeds excessively in a short time, making it difficult for the composite to uniformly coat the lithium transition metal oxide and form a uniform and continuous shell. The milling time is, for example, 5 minutes to 100 minutes, 5 minutes to 60 minutes, or 5 minutes to 30 minutes. If the milling time is excessively short, it is difficult for the composite to uniformly coat the lithium transition metal oxide and form a uniform and continuous shell. If the milling time is excessively long, the production efficiency may decrease. The content of the composite is also 3 wt% or less, 2 wt% or less, 1 wt% or less of the total weight of the lithium transition metal oxide and the composite. The content of the composite is, for example, also 0.01 to 3 wt%, 0.1 to 2 wt%, 0.1 to 1 wt% of the total weight of the lithium transition metal oxide and the composite. For example, with respect to 100 parts by weight of the mixture of the lithium transition metal oxide and the composite, the composite content is also 0.01 to 3 parts by weight, 0.1 to 3 parts by weight, 0.1 to 2 parts by weight, or 0.1 to 1 part by weight.

[0133] The average particle size (D50) of the composite used for the mechanical milling of the lithium transition metal oxide and the composite is, for example, 1 μm to 20 μm, 3 μm to 15 μm, or 5 μm to 10 μm.

[0134] In this specification, a and b in "carbon number a to b" mean the carbon number of a specific group. That is, the said group contains carbon atoms from a to b. For example, "alkyl group having 1 to 4 carbon atoms" means an alkyl group having 1 to 4 carbons, that is, CH3-, CH3CH2-, CH3CH2CH2-, (CH3)2CH-, CH3CH2CH2CH2-, CH3CH2CH(CH3)-, and (CH3)3C-.

[0135] The nomenclature for specific radicals includes, depending on the context, monoradicals or diradicals. For example, if a substituent requires two linking points to the remaining molecule, the substituent must be understood as a diradical. For example, a substituent specified for an alkyl group that requires two linking points is -CH 2-、 -CH2CH 2-、 -CH2CH(CH3)CH 2- and includes diradicals such as. Other radical nomenclatures, such as "alkylene", clearly indicate that the radical is a diradical.

[0136] As used herein, the terms "alkyl group" or "alkylene group" mean branched or unbranched aliphatic hydrocarbon groups. In one embodiment, the alkyl group may or may not be substituted. Alkyl groups include, but are not necessarily limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, etc., each of which may or may not be selectively substituted. In one embodiment, the alkyl group has 1 to 5 carbon atoms. For example, an alkyl group having 1 to 5 carbon atoms is also methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, 3-pentyl, etc., but is not necessarily limited thereto.

[0137] As used herein, the term "cyanoalkyl group" means an alkyl group to which a cyano group is attached. For example, cyanomethyl, cyanobutyl, cyanopentyl.

[0138] As used herein, the term "alkenyl group" refers to a hydrocarbon group containing 2 to 20 carbon atoms and at least one carbon-carbon double bond, including, but not limited to, ethenyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 1-butenyl group, 2-butenyl group, cyclopropenyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, etc. In one embodiment, the alkenyl group may or may not be substituted. In one embodiment, the alkenyl group can have 2 to 40 carbon atoms.

[0139] As used herein, the term "aromatic" means a ring or ring system having a conjugated π electron system, including carbocyclic aromatics (e.g., phenyl group) and heteroaromatic groups (e.g., pyridine). The term includes monocyclic or fused polycycles (i.e., rings sharing adjacent atom pairs) if the entire ring system is aromatic.

[0140] As used herein, the term "aryl group" means an aromatic ring or ring system (i.e., two or more fused rings sharing two adjacent carbon atoms) whose ring skeleton contains only carbon. If the aryl group is a ring system, each ring in the system is aromatic. For example, aryl groups include, but are not limited to, phenyl group, biphenyl group, naphthyl group, phenanthrenyl group, naphthacenyl group, etc. The aryl group may or may not be substituted.

[0141] As used herein, the term "heteroaryl group" means an aromatic ring system having a single ring or multiple fused rings, wherein one or more ring atoms are not carbon, i.e., are heteroatoms. In a fused ring system, one or more heteroatoms may be present in only one ring. For example, heteroatoms include, but are not necessarily limited to, oxygen, sulfur, and nitrogen. For example, heteroaryl groups include, but are not limited to, furanyl groups, thienyl groups, imidazolyl groups, quinazolinyl groups, quinolinyl groups, isoquinolinyl groups, quinoxalinyl groups, pyridinyl groups, pyrrolyl groups, oxazolyl groups, indolyl groups, etc.

[0142] As used herein, "halogen" is a stable element belonging to Group 17 of the Periodic Table of the Elements, and is, for example, fluorine, chlorine, bromine, or iodine, particularly fluorine and / or chlorine.

[0143] The present invention will be described in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and do not limit the scope of the present invention.

[0144] (Production of the Composite) Reference Production Example 1: Undoped Al2O3@Gr Composite After placing Al2O3 particles (average particle size: about 20 nm) in the reactor, the internal temperature of the reactor was raised to 1000 °C under the condition that CH4 was supplied at about 300 sccm and 1 atm in the reactor for about 30 minutes.

[0145] Subsequently, heat treatment was performed by holding at the above temperature for 7 hours. Subsequently, the internal temperature of the reactor was adjusted to room temperature (20 - 25 °C) to obtain Al2O3 particles and Al2O which is its reduction product. zAn undoped composite in which (0 < z < 3) particles are embedded in a carbon-based material was obtained.

[0146] The alumina content contained in the undoped composite was 60 wt%.

[0147] Production Example 1: Phosphorus (P)-doped Al2O3@Gr composite 5 g of the composite obtained in Reference Production Example 1 and 2 g of triphenyl phosphine (TPP) were added to 100 ml of ethanol and stirred at room temperature. After evaporating and removing the ethanol, the obtained mixture was dried in an oven at 150 °C for 24 hours, then put into a reactor under a nitrogen atmosphere and heat-treated at 1000 °C for 1 hour. Subsequently, the internal temperature of the reactor was adjusted to room temperature (20 - 25 °C) to obtain a composite doped with phosphorus (P) element. The phosphorus (P) element is doped into the composite by the above-mentioned high-temperature heat treatment.

[0148] (Production of composite cathode active material) Example 1: Phosphorus (P)-doped Al2O3@Gr composite 0.4 wt% (alumina 0.24 wt%) coated NCA91 LiNi 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) and the composite prepared in Production Example 1 were milled at a rotation speed of about 1000 - 2000 rpm for about 5 - 30 minutes using a Nobilta Mixer (Hosokawa, Japan) to obtain a composite cathode active material.

[0149] The mixing weight ratio of NCA and the composite obtained in Production Example 1 was 99.6:0.4.

[0150] Example 2: Phosphorus (P)-doped Al2O3@Gr composite 0.25 wt% coated NCA91 A composite cathode active material was produced in the same manner as in Example 1, except that the mixing weight ratio of NCA91 and the composite obtained in Production Example 1 was changed to 99.75:0.25.

[0151] Example 3: 0.1 wt% Coating of Phosphorus (P)-Doped Al2O3@Gr Composite on NCA91 The composite cathode active material was produced in the same manner as in Example 1, except that the mixing weight ratio of NCA91 to the composite obtained in Production Example 1 was changed to 99.9:0.1.

[0152] Example 4: 1.0 wt% Coating of Phosphorus (P)-Doped Al2O3@Gr Composite on NCA91 The composite cathode active material was produced in the same manner as in Example 1, except that the mixing weight ratio of NCA91 to the composite obtained in Production Example 1 was changed to 99.0:1.0.

[0153] Comparative Example 1: bare NCA91 NCA91 was used as the cathode active material as it was.

[0154] Reference Example 1: 0.4 wt% Coating of Undoped Al2O3@Gr Composite on NCA91 The composite cathode active material was produced in the same manner as in Example 1, except that the undoped Al2O3@Gr composite produced in Reference Production Example 1 was used instead of the phosphorus (P)-doped Al2O3@Gr composite produced in Production Example 1.

[0155] (Manufacture of Lithium Battery (Half Cell)) Example 5 (Manufacture of Cathode) A mixture of the composite cathode active material produced in Example 1, a carbon conductive material (Denka Black), and polyvinylidene fluoride (PVdF) at a weight ratio of 96:2:2 was mixed with N-methylpyrrolidone (NMP) in an agate mortar to produce a slurry.

[0156] The slurry was bar-coated on a 15-μm-thick aluminum current collector, dried at room temperature, then dried again under vacuum at 120 °C, and rolled and punched to produce a 55-μm-thick cathode plate.

[0157] The loading level of the electrode was 10.5 mg / cm 2 and the mixed density of the electrode was 3.6 g / cc.

[0158] (Manufacture of coin cells) Using the manufactured positive electrode plate, with lithium metal as the counter electrode, a PTFE separator, and a solution in which 1.15 M LiPF6 and 1.5 wt% vinylene carbonate (VC) are dissolved in EC (ethylene carbonate) + EMC (ethyl methyl carbonate) + DMC (dimethyl carbonate) (2:4:4 volume ratio) as the electrolyte, coin cells were manufactured respectively.

[0159] Examples 6 to 8 Coin cells were manufactured in the same manner as in Example 5, except that the composite positive electrode active materials prepared in Examples 2 to 4 were used respectively instead of the composite positive electrode active material manufactured in Example 1.

[0160] Comparative Example 2 Coin cells were manufactured in the same manner as in Example 5, except that the composite positive electrode active material prepared in Comparative Example 1 was used respectively instead of the composite positive electrode active material manufactured in Example 1.

[0161] Reference Example 2 Coin cells were manufactured in the same manner as in Example 5, except that the composite positive electrode active material prepared in Reference Example 1 was used respectively instead of the composite positive electrode active material manufactured in Example 1.

[0162] Evaluation Example 1: XPS spectrum evaluation During the manufacturing process of the undoped composite manufactured in Reference Production Example 1, XPS spectra were measured using Quantum 2000 (Physical Electronics) over time. The XPS spectra of the C 1s orbital and the Al 2p orbital for the samples before heating, after 1 minute, after 5 minutes, after 30 minutes, after 1 hour, and after 4 hours were measured respectively. At the initial stage of heating, only the peak for the Al 2p orbital was shown, and the peak for the C 1s orbital was not shown. After 30 minutes, the peak for the C 1s orbital was clearly shown, and the size of the peak for the Al 2p orbital decreased significantly.

[0163] After 30 minutes, peaks related to the C 1s orbital due to C-C bonds and C=C bonds caused by the growth of graphene were clearly shown near 284.5 eV.

[0164] As the reaction time elapsed, the oxidation number of aluminum decreased, and the peak position of the Al 2p orbital shifted to the side with a lower binding energy (eV).

[0165] Therefore, as the reaction proceeded, graphene grew on the Al2O3 particles, and it was confirmed that Al2O x (0 < x < 3) which is the reduction product of Al2O3 was generated.

[0166] The average contents of carbon and aluminum were measured through the XPS analysis results in 10 regions of the composite sample manufactured in Reference Production Example 1. The deviation of the aluminum content for each region was calculated for the measurement results. The deviation of the aluminum content was shown as a percentage with respect to the average value, and this was referred to as the uniformity. The percentage with respect to the average value of the deviation of the aluminum content, that is, the uniformity of the aluminum content, was 1%. Therefore, it was confirmed that alumina was uniformly distributed in the composite manufactured in Reference Production Example 1.

[0167] Evaluation Example 2: XPS Spectrum Evaluation The XPS spectra of the undoped composite produced in Reference Production Example 1 and the doped composite produced in Production Example 1 are shown in FIG. 1, respectively.

[0168] As shown in FIG. 1, the doped composite produced in Production Example 1 further showed a peak related to the phosphorus (P) element. Therefore, it was confirmed that the doped composite produced in Production Example 1 was doped with the phosphorus (P) element.

[0169] On the other hand, the undoped composite produced in Reference Production Example 1 did not show a peak related to the phosphorus (P) element.

[0170] The element contents obtained from the XPS spectra of the undoped composite produced in Reference Production Example 1 and the doped composite produced in Production Example 1 are shown in Table 1 below.

[0171]

Table 1

[0172] As shown in Table 1, the undoped composite produced in Reference Production Example 1 did not contain the phosphorus (P) element. On the other hand, the phosphorus (P) element content of the phosphorus (P)-doped composite produced in Production Example 1 was 0.7 at%.

[0173] Evaluation Example 3: SEM, HR-TEM and SEM-EDAX Analyses Scanning electron microscopy, high-resolution transmission electron microscopy and EDAX analysis were performed on the undoped composite produced in Reference Production Example 1, the phosphorus (P)-doped composite produced in Production Example 1, the composite positive electrode active material produced in Example 1, and the bare NCA of Comparative Example 1.

[0174] FEI Titan80-300 of Philips was used during the SEM-EDAX analysis.

[0175] The undoped composite produced in Reference Production Example 1 has a structure in which Al2O3 particles and Al2O z (0 < z < 3) particles are embedded in graphene. It was confirmed that a graphene layer is disposed on the outer contour of one or more particles selected from among Al2O3 particles and Al2O z (0 < z < 3). One or more particles selected from among Al2O3 particles and Al2O z (0 < z < 3) are uniformly dispersed in the graphene matrix. The particle size of one or more of the Al2O3 particles and Al2O z (0 < z < 3) particles was about 20 nm. The particle size of the undoped composite produced in Reference Production Example 1 was about 100 nm to 200 nm. The phosphorus (P)-doped composite produced in Production Example 1 also exhibited a structure and particle size substantially equal to those of the composite produced in Reference Production Example 1.

[0176] It was confirmed that a shell formed of a composite containing graphene doped with phosphorus (P) is disposed on the NCA core in the composite positive electrode active material produced in Example 1.

[0177] SEM-EDAX analysis was performed on the bare NCA of Comparative Example 1 and the composite positive electrode active material produced in Example 1.

[0178] It was confirmed that the concentration of aluminum (Al) distributed on the surface of the composite positive electrode active material of Example 1 increases compared to the surface of the bare NCA composite positive electrode active material of Comparative Example 1.

[0179] Therefore, it was confirmed that the phosphorus (P)-doped composite produced in Production Example 1 is uniformly coated on the NCA core in the composite positive electrode active material of Example 1 to form a shell.

[0180] Evaluation Example 4: Charge and Discharge Characteristics Evaluation at Room Temperature (25°C) The lithium batteries manufactured in Examples 5 to 8, Comparative Example 2, and Reference Example 2 were subjected to constant current charging at 25°C with a current of 0.1C rate until the voltage reached 4.4V (vs. Li), and then, while maintaining 4.4V in the constant voltage mode, cut-off was performed with a current of 0.05C rate. Subsequently, discharging was carried out at a constant current of 0.1C rate until the voltage reached 2.8V (vs. Li) during discharge (formation cycle).

[0181] The lithium batteries that had undergone the formation cycle were charged at a constant current of 0.2C rate at 25°C until the voltage reached 4.4V (vs. Li), and then, while maintaining 4.4V in the constant voltage mode, cut-off was performed with a current of 0.05C rate. Subsequently, discharging was carried out at a constant current of 0.2C rate until the voltage reached 2.8V (vs. Li) during discharge (first cycle). Such cycles were repeated under the same conditions up to the 100th cycle (100 times repetition).

[0182] After each charge / discharge cycle in all charge / discharge cycles, a 10-minute stop time was provided. A part of the room temperature charge / discharge experiment results is shown in Table 2 below. The initial efficiency is defined by the following Equation 1.

[0183] <Equation 1> Initial efficiency [%] = [Discharge capacity in formation cycle / Charge capacity in formation cycle] × 100

[0184]

Table 2

[0185] As shown in Table 2, the lithium battery of Example 5 showed an initial efficiency at a level equivalent to that of the lithium battery of Comparative Example 2 and showed an improved initial efficiency compared to Reference Example 2.

[0186] Evaluation Example 5: Evaluation of Charge / Discharge Characteristics at High Temperature (45°C) The lithium batteries manufactured in Examples 5 to 8, Comparative Example 2, and Reference Example 2 were subjected to constant current charging at 45 °C at a current of 0.1 C rate until the voltage reached 4.4 V (vs. Li), and then, while maintaining 4.4 V in the constant voltage mode, cut-off was performed at a current of 0.05 C rate. Subsequently, discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during discharge (formation cycle).

[0187] The lithium batteries that had undergone the formation cycle were subjected to constant current charging at 45 °C at a current of 0.2 C rate until the voltage reached 4.4 V (vs. Li), and then, while maintaining 4.4 V in the constant voltage mode, cut-off was performed at a current of 0.05 C rate. Subsequently, discharge was performed at a constant current of 0.2 C rate until the voltage reached 2.8 V (vs. Li) during discharge (first cycle). Such cycles were repeated under the same conditions up to the 100th cycle (100 repetitions).

[0188] After each charge / discharge cycle in all charge / discharge cycles, a 10-minute stop time was provided. A part of the high-temperature charge / discharge experiment results is shown in Table 3 below. The capacity retention rate at the 100th cycle is defined by the following Equation 2.

[0189] <Equation 2> Capacity retention rate [%] = [Discharge capacity at the 100th cycle / Discharge capacity at the first cycle] × 100

[0190] Evaluation Example 6: Evaluation of Direct Current Internal Resistance (DC-IR) Before and After High-Temperature Charge / Discharge For the lithium batteries manufactured in Examples 5 to 8, Comparative Example 2, and Reference Example 2, the direct current internal resistance (DC-IR) was measured by the following method before and after the high-temperature charge / discharge evaluation.

[0191] After charging to the voltage at 50% state of charge (SOC) at a current of 0.5 C in the first cycle, after cut-off at 0.02 C and after resting for 10 minutes, After discharging at a constant current of 0.5C for 30 seconds, resting for 30 seconds, charging at a constant current of 0.5C for 30 seconds, and resting for 10 minutes, After discharging at a constant current of 1.0C for 30 seconds, resting for 30 seconds, charging at a constant current of 0.5C for 1 minute, and resting for 10 minutes, After discharging at a constant current of 2.0C for 30 seconds, resting for 30 seconds, charging at a constant current of 0.5C for 2 minutes, and resting for 10 minutes, After discharging at a constant current of 3.0C for 30 seconds, resting for 30 seconds, charging at a constant current of 0.5C for 3 minutes, and resting for 10 minutes.

[0192] The direct current internal resistance (DC-IR, R = ΔV / ΔI) was calculated from the ratio of the average voltage change (ΔV) and the average current change (ΔI) during constant current discharge at each C-rate, and their average values were taken as the measured values.

[0193] A part of the measured direct current internal resistance before the high-temperature charge-discharge evaluation and the direct current internal resistance after the high-temperature charge-discharge evaluation is shown in Table 3 below.

[0194]

Table 3

[0195] As shown in Table 3, the lithium batteries of Examples 5 to 8 showed significantly improved high-temperature life characteristics compared to the lithium battery of Comparative Example 2. Also, in the lithium batteries of Examples 5 to 8, the increase in the direct current internal resistance after high-temperature charge-discharge was significantly suppressed compared to the lithium battery of Comparative Example 2.

Industrial Applicability

[0196] According to one aspect, by providing that the composite positive electrode active material includes a shell containing a first metal oxide, a carbon-based material, and a doped phosphorus (P) element, the high-temperature cycle characteristics of the lithium battery are improved, and an increase in the internal resistance is suppressed.

Explanation of Symbols

[0197] 1 Lithium battery 2 Negative electrode 3 Positive electrode 4 Separator 5 Battery case 6 Cap assembly

Claims

1. A core containing a lithium transition metal oxide, and a shell disposed along the surface of the core, wherein wherein the shell is a chemical formula M ａ O ｂ including one or more first metal oxides represented by (0 < a ≤ 3, 0 < b < 4, and if a is 1, 2, or 3, b is not an integer), a carbon-based material, and a doped phosphorus (P) element the first metal oxide is disposed within a carbon-based material matrix, and M is one or more metals selected from Groups 2 to 13, 15, and 16 of the Periodic Table of the Elements, the lithium transition metal oxide has a nickel content of 80 mol% or more based on the total number of moles of transition metals, the first metal oxide is a composite cathode active material that is a reduction product of metal oxide particles.

2. The composite cathode active material according to Claim 1, wherein the content of the doped phosphorus (P) element contained in the shell is more than 0 and 5 at% or less based on the total number of atoms of the shell.

3. The composite cathode active material according to Claim 1, wherein the content of the first metal contained in the shell is more than 0 and 10 at% or less based on the total number of atoms of the shell, and the oxygen content contained in the shell is more than 0 and 10 at% or less based on the total number of atoms of the shell.

4. The composite cathode active material according to Claim 1, wherein the carbon content contained in the shell is 80 to 99 at% based on the total number of atoms of the shell.

5. The composite cathode active material according to Claim 1, wherein the metal contained in the first metal oxide is one or more metals selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se.

6. The first metal oxide is Al ２ O ｚ (0 < z < 3), NbO ｘ (0 < x < 2.5), MgO ｘ (0 < x < 1), Sc ２ O ｚ (0 < z < 3), TiO ｙ (0 < y < 2), ZrO ｙ (0 < y < 2), V ２ O ｚ (0 < z < 3), WO ｙ (0 < y < 2), MnO ｙ (0 < y < 2), Fe ２ O ｚ (0 < z < 3), Co ３ O ｗ (0 < w < 4), PdO ｘ (0 < x < 1), CuO ｘ (0 < x < 1), AgO ｘ (0 < x < 1), ZnO ｘ (0 < x < 1), Sb ２ O ｚ (0 < z < 3), and SeO ｙ (0 < y < 2), and is one or more selected from among them, the composite positive electrode active material according to claim 1.

7. wherein the shell is a chemical formula M ａ O ｃ further includes a second metal oxide represented by (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer), The second metal oxide contains the same metal as the first metal oxide, and the c / a ratio of the second metal oxide has a value that is even larger than the b / a ratio of the first metal oxide, which is the ratio of a to b of the first metal oxide.

8. wherein the second metal oxide is Al ２ O ３ , NbO, NbO ２ , Nb ２ O ５ , MgO, Sc ２ O ３ , TiO ２ , ZrO ２ , V ２ O ３ , WO ２ , MnO ２ , Fe ２ O ３ , Co ３ O ４ , PdO, CuO, AgO, ZnO, Sb ２ O ３ , and SeO ２ selected from among The composite cathode active material according to Claim 7, wherein the first metal oxide is a reduction product of the second metal oxide.

9. The composite cathode active material according to Claim 1, wherein the thickness of the shell is 1 nm to 5 μm.

10. The composite cathode active material according to Claim 1, wherein the carbon-based material is graphene.

11. The shell contains a composite including the first metal oxide, the carbon-based material, and the doped phosphorus (P) element, and the content of the composite is 3 wt% or less of the total weight of the composite cathode active material.

12. The carbon-based material has a branched structure, and the metal oxide is distributed within the branched structure. The branched structure is the composite cathode active material according to claim 11, including a plurality of carbon-based material particles in contact with each other.

13. The carbon-based material has one or more structures selected from a spherical structure, a spiral structure in which the spherical structures are connected, and a cluster structure in which the spherical structures are aggregated. The first metal oxide is distributed within the spherical structure, the size of the spherical structure is 50 nm to 300 nm, the size of the spiral structure is 500 nm to 100 μm, and the size of the cluster structure is 0.5 mm to 10 cm. The composite is a faceted-ball structure or a planar structure, and one or more selected from the first metal oxide and the second metal oxide are distributed inside or on the surface of the structure. The carbon-based material extends a distance of 10 nm or less in the first metal oxide and includes at least 1 to 20 carbon-based material layers, and the total thickness of the carbon-based material is 0.6 to 12 nm. The composite cathode active material according to claim 11.

14. The composite cathode active material according to claim 1, wherein the lithium transition metal oxide is represented by the following Chemical Formula 1 to Chemical Formula 5: <Chemical Formula 1> Li ａ Ni ｘ Co ｙ M ｚ O ２－ｂ A ｂ In the Chemical Formula 1, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.8 ≤ x < 1, 0 < y ≤ 0.3, 0 < z ≤ 0.3, and x + y + z = 1. M is one or more selected from the group consisting of manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), and boron (B). A is F, S, Cl, Br, or a combination thereof. <Chemical Formula 2> LiNi ｘ Co ｙ Mn ｚ O ２ <Chemical Formula 3> LiNi ｘ Co ｙ Al ｚ O ２ In the Chemical Formulas 2 and 3, 0.8 ≤ x ≤ 0.95, 0 < y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1. <Chemical Formula 4> LiNi ｘ Co ｙ Mn ｚ Al ｗ O ２ In the Chemical Formula 4, 0.8 ≤ x ≤ 0.95, 0 < y ≤ 0.2, 0 < z ≤ 0.2, 0 < w ≤ 0.2, and x + y + z + w = 1. <Chemical Formula 5> Li ａ Co ｘ M ｙ O ２－ｂ A ｂ In the Chemical Formula 5, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, and x + y = 1. M is one or more selected from the group consisting of manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), and boron (B), A is F, S, Cl, Br, or a combination thereof.

15. A positive electrode comprising the composite positive electrode active material according to any one of Claims 1 to 14.

16. The positive electrode according to Claim 15, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, a lithium battery.

17. providing a lithium transition metal oxide; providing a composite; mechanically milling the lithium transition metal oxide and the composite, wherein the complex has the chemical formula M ａ O ｂ (0 < a ≤ 3, 0 < b < 4; if a is 1, 2, or 3, then b is not an integer), and contains one or more first metal oxides, a carbon-based material, and a doped phosphorus (P) element wherein the first metal oxide is disposed within a carbon-based material matrix, and M is one or more metals selected from Groups 2 to 13, 15, and 16 of the Periodic Table of the Elements, the lithium transition metal oxide has a nickel content of 80 mol% or more based on the total number of moles of transition metals, the first metal oxide is a reduction product of metal oxide particles, a method for producing a composite positive electrode active material.

18. The step of providing the composite includes M ａ O ｃ Supplying a reaction gas composed of a carbon source gas to one or more second metal oxides represented by (0 < a ≤ 3, 0 < c ≤ 4, where if a is 1, 2, or 3, c is an integer), and heat-treating to provide an undoped composite; mixing and heat-treating an undoped composite and a phosphorus (P)-containing compound to prepare a composite, wherein M is one or more metals selected from Groups 2 to 13, 15, and 16 of the Periodic Table of the Elements, the method for producing a composite positive electrode active material according to Claim 17.

19. The method for producing a composite positive electrode active material according to Claim 18, wherein the phosphorus (P)-containing compound is a compound represented by the following Chemical Formulas 6 to 7: 【Chemical 1】 【Chemical 2】 In the formula, X １ , X ２ and X ３ are independently of each other a covalent bond, O, S or NR ４ wherein R １ 、 R ２ 、 R ３ and R ４ are each independently a halogen-substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a halogen-substituted or unsubstituted cyanoalkyl group having 1 to 10 carbon atoms, a halogen-substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, a halogen-substituted or unsubstituted aryl group having 5 to 20 carbon atoms, a halogen-substituted or unsubstituted heteroaryl group having 2 to 20 carbon atoms, or -Si(R ５ )(R ６ )(R ７ ), and R ５ , R ６ and R ７ are each independently a halogen-substituted or unsubstituted alkyl group having 1 to 5 carbon atoms.

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