Composite positive electrode active material, positive electrode including same, and lithium battery

Abstract

Provided are a composite positive electrode active material, a positive electrode including the same, and a lithium battery, the composite positive electrode active material including: a first core (first core) including a first lithium transition metal oxide; a second core (second core) including a second lithium transition metal oxide; and a shell disposed along a surface of at least one of the first core and the second core, the shell including: at least one type of first metal oxide; and a first carbon-based material, in which a first metal oxide is disposed in the first carbon-based material matrix, the first metal oxide being formed by the chemical formula MaOb (0lt; a < = 3, 0lt; blt; 4, if a is 1, 2 or 3; and b is not an integer), M is at least one metal selected from group 2 to group 13, group 15, and group 16 of the periodic table, the first lithium transition metal oxide and the second lithium transition metal oxide have different particle sizes, the first lithium transition metal oxide has a layered crystal structure and an Ni content of 60 mol% or more, and the second lithium transition metal oxide has a layered crystal structure and an Ni content of 60 mol% or more. And the second lithium transition metal oxide has an olivine-based crystal structure.

Description

Technical Field

[0001] A composite positive electrode active material, a positive electrode including the composite positive electrode active material, and a lithium battery are disclosed.

[0002] For miniaturization and high performance of various devices, in addition to making lithium batteries smaller and lighter, high energy density of lithium batteries has become increasingly important. In other words, high-capacity lithium batteries have become important. Background Art

[0003] Existing high-capacity composite positive electrode active materials have problems of side reactions with electrolytes and thermal stability. In this regard, composite positive electrode active materials having high capacity, suppressed side reactions with electrolytes, and excellent thermal stability are being studied. Summary of the Invention

[0004] Technical Problem One aspect is to provide a new composite positive electrode active material that reduces surface side reactions with electrolytes and has excellent thermal stability.

[0005] Another aspect is to provide a positive electrode including the composite positive electrode active material.

[0006] Another aspect is to provide a lithium battery including the positive electrode.

[0007] Technical Solution According to one aspect, the composite positive electrode active material includes: A first core (Core 1), including a first lithium transition metal oxide; A second core (Core 2), including a second lithium transition metal oxide; and A shell, disposed on the surface of at least one of the first core and the second core, The shell includes: at least one type of first metal oxide; and a first carbonaceous material, wherein at least one type of first metal oxide is disposed in the matrix of the first carbonaceous material, At least one type of first metal oxide is represented by the formula M , ,

[0005] , ,

[0003] ,

[0007] , , , , b , ,

[0006] , ,

[0004] , , , , , , , , a , , , O b (0 < a ≤ 3, 0 < b < 4, when a is 1, 2, or 3, b is not an integer), M is at least one metal of Groups 2 to 13, 15, and 16 of the periodic table, The first lithium transition metal oxide and the second lithium transition metal oxide have different particle sizes, The first lithium transition metal oxide has a layered crystal structure and a nickel (Ni) content of 60 mol% or more, and The second lithium transition metal oxide has an olivine-based crystal structure.

[0008] According to another aspect, the positive electrode includes: Positive electrode current collector; and A positive electrode active material layer is disposed on one or both sides of the positive electrode current collector and includes the composite positive electrode active material and a binder.

[0009] According to another perspective, lithium batteries include: A positive electrode, a negative electrode, and an electrolyte are arranged between the positive and negative electrodes.

[0010] Beneficial effects of the invention According to one aspect, the composite positive electrode active material reduces side reactions with the electrolyte and improves conductivity and thermal stability. Therefore, lithium batteries using this composite positive electrode active material can have improved high-temperature cycle characteristics and improved thermal stability. Attached Figure Description

[0011] Figure 1 This is a schematic cross-sectional view of the dry composite positive electrode active material according to an embodiment.

[0012] Figure 2 This is a schematic cross-sectional view of the dry composite positive electrode active material according to an embodiment.

[0013] Figure 3 This is a scanning electron microscope image showing the surface of the composite positive electrode active material prepared in Example 1.

[0014] Figure 4 This is a graph showing the specific capacity of the composite positive electrode active materials of Examples 1 to 4.

[0015] Figure 5 The graphs show the cycle characteristics of lithium batteries that include the positive electrode active materials prepared in Example 1 and Comparative Examples 1 to 3, respectively.

[0016] Figure 6 This is a schematic diagram of a lithium battery according to an embodiment.

[0017] Figure 7 This is a schematic diagram of a lithium battery according to an embodiment.

[0018] Figure 8 This is a schematic diagram of a lithium battery according to an embodiment. Detailed Implementation

[0019] Various embodiments are illustrated in the accompanying drawings. However, the inventive concept can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. The same reference numerals denote the same components.

[0020] What will be understood is that when an element is referred to as "on" another element, it can be directly on top of the other element, or the other element can be placed between them. Conversely, when an element is referred to as "directly on" another element, there is no intervening element between them.

[0021] Although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or areas, these elements, components, regions, layers, and / or areas should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or area from another. Therefore, without departing from the teachings herein, the first component, ingredient, region, layer, or area described below may be referred to as the second component, ingredient, region, layer, or area.

[0022] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the inventive concept. As used herein, unless the context clearly specifies otherwise, the singular form is intended to include the plural form containing “at least one (species / person)”. “At least one (species / person)” should not be construed as limited to the singular. As used herein, the term “and / or” includes any and all combinations of one or more of the listed items. The terms “comprising” and / or “including” as used in the detailed description indicate the presence of the detailed features, regions, integers, steps, operations, components, and / or ingredients, and do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, components, and / or ingredients.

[0023] To facilitate the description of the relationship between one component or feature and another, spatial relative terms such as “below,” “under,” “lower,” “top,” “above,” and “upper” are used. It will be understood that, in addition to the orientations shown in the figures, spatial relative terms are intended to encompass different orientations of the device during use or operation. For example, when the device in the figures is flipped, a component described as “below” or “bottom” of other elements or features will be oriented “above” other elements or features. Thus, the exemplary term “below” can encompass both upper and lower directions. The device may be positioned in other orientations (rotated 90 degrees or rotated in other directions), and the spatial relative terms used herein will be interpreted accordingly.

[0024] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, terms (such as those defined in common dictionaries) shall be interpreted as having the same meaning as in the relevant technology and disclosure, and shall not be interpreted as idealized.

[0025] Exemplary embodiments are described with reference to cross-sectional views, which are schematic representations of idealized embodiments. Thus, variations in shape as shown should be expected due to factors such as manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shape of the regions shown herein, but should include shape deviations, for example, due to manufacturing processes. For example, regions shown or described as flat areas may generally have rough and / or non-linear characteristics. Furthermore, angles shown as sharp corners may be rounded (or chamfered). Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the precise shape of the regions, nor are they intended to limit the scope of the claims.

[0026] "Group" refers to the group of elements in the periodic table according to the group system of groups 1 to 18 of the International Union of Pure and Applied Chemistry ("IUPAC").

[0027] In this specification, if the particles are spherical, the term "particle size" refers to the average diameter of the particles, and if the particles are non-spherical, the term "particle size" refers to the average length of the major axis of the particles. Particle size can be measured using a particle size analyzer (PSA). "Particle size" refers to, for example, the average particle size. The "average particle size" can be, for example, the median particle size D50.

[0028] For example, the median particle size D50 refers to the particle size corresponding to 50% of the cumulative volume calculated from the particle with the smallest particle size in the particle size distribution measured by, for example, laser diffraction.

[0029] For example, the average particle size D90 refers to the particle size corresponding to 90% of the cumulative volume calculated from the particle with the smallest particle size in the particle size distribution measured by, for example, laser diffraction.

[0030] For example, the average particle size D10 refers to the particle size corresponding to 10% of the cumulative volume calculated from the particle with the smallest particle size in the particle size distribution measured by, for example, laser diffraction.

[0031] As used herein, the term "metal" can include both metals in an elemental or ionic state and metalloids (such as silicon and germanium).

[0032] The term "alloy" as used here can refer to a mixture of two or more metals.

[0033] As used herein, the term "electrode active material" refers to electrode materials that can undergo lithiation and delithiation.

[0034] As used here, the term "positive electrode active material" can refer to a positive electrode material that can undergo lithiation and delithiation.

[0035] As used here, the term "negative electrode active material" can refer to a negative electrode material that can undergo lithiation and delithiation.

[0036] As used here, the terms “lithiation” and “carrying lithiation” refer to the process of adding lithium to the active material of an electrode.

[0037] As used herein, the terms “delithiation” and “performing delithiation” refer to the process of removing lithium from the active material of an electrode.

[0038] The terms “charging” and “performing a charge” as used here can refer to the process by which a battery provides electrochemical energy.

[0039] As used here, the terms “discharge” and “to discharge” can refer to the process of removing electrochemical energy from a battery.

[0040] As used herein, the terms "positive electrode" and "cathode" can refer to the electrode that undergoes electrochemical reduction and lithiation during discharge.

[0041] As used herein, the terms “negative electrode” and “anode” can refer to the electrode that undergoes electrochemical oxidation and delithiation during discharge.

[0042] While specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently foreseen or unforeseen by the applicant or those skilled in the art will be apparent. Therefore, the appended claims, as filed and as may be amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0043] In the following, the composite positive electrode active material, the positive electrode including the composite positive electrode, and the lithium battery will be described in further detail according to exemplary embodiments.

[0044] [Composite positive electrode active material] The composite positive electrode active material according to an embodiment includes: a first core (first core) comprising a first lithium transition metal oxide; a second core (second core) comprising a second lithium transition metal oxide; and a shell disposed on the surface of at least one of the first core and the second core, the shell comprising at least one type of first metal oxide and a first carbon-based material, wherein the first metal oxide is disposed in a first carbon-based material matrix, and the first metal oxide is of formula M a O b(where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3, b is not an integer), M represents at least one metal selected from Groups 2 to 13, 15, and 16 of the Periodic Table, the first lithium transition metal oxide and the second lithium transition metal oxide have different particle sizes, the first lithium transition metal oxide has a layered crystal structure and a Ni content of 60 mol% or more, and the second lithium transition metal oxide has an olivine-type crystal structure.

[0045] Reference Figure 1 , the composite positive electrode active material 100 includes a first core 10, a second core 20, and a shell 30 disposed continuously or discontinuously along the surface of at least one of the first core 10 and the second core 20. The shell 30 may cover all or part of the first core 10 and the second core 20. The shell 30 may include a first metal oxide 31 and a first carbonaceous material 32. The composite positive electrode active material 100 may be, for example, a dry composite positive electrode active material that is not impregnated, dissolved, or dispersed in a processing solvent during the manufacture of the positive electrode, or a wet composite positive electrode active material that is impregnated, dissolved, or dispersed in a processing solvent during the manufacture of the positive electrode. The composite positive electrode active material 100 may be, for example, a dry composite positive electrode active material that does not include a processing solvent or is not in contact with a processing solvent in the process of manufacturing the positive electrode, or a wet composite positive electrode active material that includes a processing solvent or is in contact with a processing solvent in the process of manufacturing the positive electrode.

[0046] The composite positive electrode active material 100 may have, for example, a first core 仃0 / shell 30 structure and / or a second core 20 / shell 30 structure. The first core 10 and the second core 20 may have, for example, different particle sizes. The first core 10 / shell 30 structure and the second core 20 / shell 30 structure may have different particle sizes.

[0047] The composite positive electrode active material 100 can have a mixed structure of a first core 10 / shell 30 and a second core 20 / shell 30, thus achieving improved mixture density and specific capacity. For example, regarding the mixed structure of the first core 10 / shell 30 and the second core 20 / shell 30 in the composite positive electrode active material 100, the first core 10 and the second core 20 have different particle sizes, allowing the second core 20 / shell 30 structure to be arranged in the gaps between multiple first core 10 / shell 30 structures, thereby improving the overall mixture density and specific capacity of the composite positive electrode active material 100. With the improvement in the mixture density and specific capacity of the composite positive electrode active material 100, the capacity characteristics of the lithium battery including the composite positive electrode active material 100 can be improved accordingly. Furthermore, when the shell 30 of the composite positive electrode active material 100 includes a first carbon-based material 32, the conductivity and thermal stability of the composite positive electrode active material 100 can be improved. With the improvement of the conductivity and thermal stability of the composite positive electrode active material 100, the capacity characteristics and cycle characteristics of lithium batteries including the composite positive electrode active material 100 at high temperatures can be improved accordingly.

[0048] For example, the first core 10 can be a large-diameter positive electrode active material, and the particle size of the first core 10 is larger than that of the second core 20. For example, the first core 10 can be a large-diameter lithium transition metal oxide, and the particle size of the first core 10 is larger than that of the second core 20. For example, the second core 20 can be a small-diameter positive electrode active material, and the particle size of the second core 20 is smaller than that of the first core 10. For example, the second core 20 can be a small-diameter lithium transition metal oxide, and the particle size of the second core 20 is smaller than that of the first core 10. For example, the first lithium transition metal oxide included in the first core 10 can be a large-diameter positive electrode active material, and the second lithium transition metal oxide included in the second core 20 can be a small-diameter positive electrode active material. For example, the second lithium transition metal oxide with an average particle size smaller than the average particle size of the first lithium transition metal oxide can be arranged in the voids between the first lithium transition metal oxides. When the second lithium transition metal oxide, as small-diameter particles, is arranged in the voids between the first lithium transition metal oxides, as large-diameter particles, the ionic conductivity and electronic conductivity of the positive electrode including the composite positive electrode active material 100 can be improved simultaneously. Furthermore, the energy density of the positive electrode, including the composite positive electrode active material 100, can be further improved. Therefore, the energy density of the lithium battery including the composite positive electrode active material 100 can be improved, and consequently, the cycle characteristics of the same lithium battery can be improved.

[0049] The first lithium transition metal oxide and the second lithium transition metal oxide can have, for example, a bimodal particle size distribution in the particle size distribution diagram. For example, the composite positive electrode active material 100 can have a bimodal particle size distribution with two peaks in the particle size distribution diagram obtained by using a particle size analyzer (PSA) or the like. The bimodal particle size distribution can have a first peak corresponding to the first lithium transition metal oxide and a second peak corresponding to the second lithium transition metal oxide.

[0050] The ratio of the particle size of the first lithium transition metal oxide to the particle size of the second lithium transition metal oxide can be, for example, 3:1 to 40:1, 3:1 to 30:1, 3:1 to 20:1, 3:1 to 10:1, or 3:1 to 5:1. When the ratio of the particle size of the first lithium transition metal oxide to the particle size of the second lithium transition metal oxide is within the above range, the energy density and cycle characteristics of the lithium battery including the composite positive electrode active material can be further improved.

[0051] The particle size of the first lithium transition metal oxide can be, for example, greater than 10 μm and less than or equal to 30 μm, 11 μm to 25 μm, 11 μm to 20 μm, or 11 μm to 15 μm. The particle size of the first lithium transition metal oxide can be, for example, the median particle size D50.

[0052] The particle size of the second lithium transition metal oxide can be, for example, 1 μm to 10 μm, 1 μm to 9 μm, 1 μm to 8 μm, 1 μm to 5 μm, or 1 μm to 4 μm.

[0053] The particle size of the second lithium transition metal oxide can be, for example, a median particle size D50. When the average particle size of the first and second lithium transition metal oxides is within the above range, the energy density and cycle characteristics of the lithium battery including the composite positive electrode active material 100 can be further improved. The particle size of the first and second lithium transition metal oxides can be measured, for example, using a measuring device employing laser diffraction or dynamic light scattering. The particle size can be measured, for example, using a laser scattering particle size analyzer (e.g., Horiba Ltd. LA-920), and is the median particle size D50 value when accumulating 50% of the particles by volume, starting from the smallest particle. Optionally, the particle size of the first and second lithium transition metal oxides can be measured by scanning electron microscopy (SEM) images or using optical microscopy images.

[0054] The weight ratio of the first lithium transition metal oxide to the second lithium transition metal oxide can be, for example, from 90:10 to 60:40, from 85:15 to 65:35, from 80:20 to 65:35, or from 75:25 to 65:35. When the weight ratio of the first lithium transition metal oxide to the second lithium transition metal oxide is within the above range, the energy density and / or cycle characteristics of the lithium battery including the composite positive electrode active material 100 can be further improved.

[0055] The first core 10 may include a first lithium transition metal oxide, and the second core 20 may include a second lithium transition metal oxide.

[0056] The first lithium transition metal oxide may have, for example, a layered crystal structure and have a Ni content of 60 mol% or more, and the second lithium transition metal oxide may have, for example, an olivine crystal structure. The first lithium transition metal oxide may be, for example, a first lithium transition metal oxide having a layered crystal structure and a Ni content of 60 mol% or more, and high-capacity characteristics of the composite positive electrode active material including the first lithium transition metal oxide can be easily achieved. The second lithium transition metal oxide may have, for example, an olivine crystal structure, and thus thermal stability characteristics of the composite positive electrode active material including the second lithium transition metal oxide can be easily achieved. In this regard, the composite positive electrode active material including both the first lithium transition metal oxide and the second lithium transition metal oxide can have both high-capacity characteristics and thermal stability characteristics.

[0057] The first core 10 may include, for example, a compound selected from lithium transition metal oxides represented by Formula 1 to Formula 6. The first lithium transition metal oxide may be represented by a formula selected from Formula 1 to Formula 6: <Formula 1> Li a Ni x Co y M z O 2-b A b Wherein, in 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 manganese (Mn), cobalt (Co), 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, <Formula 2> LiNix Co y Mn z O2 <Formula 3> LiNi x Co y Al z O2 Wherein, in Formula 2 and Formula 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1, <Formula 4> LiNi x Co y Mn z Al w O2 Wherein, in 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, <Formula 5> Li a Co x M y O 2-b A b Wherein, in 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), cobalt (Co), 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, <Formula 6> Li a Ni x Mn y M' z O 2-b A b Wherein, in Formula 6, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0 < x ≤ 0.3, 0.5 ≤ y < 1, 0 < z ≤ 0.3, and x + y + z = 1, M' can be cobalt (Co), 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 can be F, S, Cl, Br, or a combination thereof.

[0058] The second core 20 can include, for example, a compound selected from lithium transition metal oxides represented by Formula 7 and Formula 8. The second lithium transition metal oxide can be represented by a formula selected from Formula 7 and Formula 8: <Formula 7> Li a M1 x M2 y PO 4-b X b Wherein, in Formula 7, 0.90 ≤ a ≤ 1.1, 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0.9 < x + y < 1.1, and 0 ≤ b ≤ 2, M1 can be chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof, M2 can be Mg, Ca, Sr, Ba, Ti, Zn, B, Nb, Ga, In, Mo, W, Al, Si, Cr, V, Sc, Y, or a combination thereof, and X can be O, F, S, P, or a combination thereof.

[0059] <Formula 8> Li a M3 z PO4 Wherein, in Formula 8, 0.90 ≤ a ≤ 1.1, 0.9 ≤ z ≤ 1.1, and M3 can be Cr, Mn, Fe, Co, Ni, Cu, Zr, or a combination thereof.

[0060] The composite positive electrode active material 100 can have a first core 10 / shell 30 structure and / or a second core 20 / shell 30 structure, wherein the shell 30 can be arranged continuously or discontinuously along the surface of the first core 10 or the surface of the second core 20. The composite positive electrode active material 100 can have a mixed structure of first core 10 / shell 30 and second core 20 / shell 30, wherein the shell 30 can be arranged continuously or discontinuously along the surface of the first core 10 and the surface of the second core 20.

[0061] The shell 30 comprises a first metal oxide disposed in a matrix of the first carbon-based material 32, thus allowing the shell 30 to be more uniformly disposed on the first core 10 or the second core 20. For example, the shell 30 may be derived from a composite comprising a first metal oxide 31 disposed in a matrix of the first carbon-based material 32, and then introduced onto the first core 10 or the second core 20, thus allowing for more uniform disposal without aggregation. The shell 30, uniformly disposed on the first core 10 or the second core 20, effectively blocks contact between the core and the electrolyte, thereby preventing side reactions caused by contact between the electrolyte and the first core 10 or the second core 20. Furthermore, ion mixing (e.g., cation mixing) caused by contact between the electrolyte and the first core 10 or the second core 20 can be suppressed, thereby suppressing the formation of a resistive layer on the surface of the first core 10 or the second core 20. Additionally, by introducing the shell 30 onto the first core 10 or the second core, the leaching of transition metal ions from the first core 10 or the second core 20, which both comprise transition metals, can be suppressed. The first carbon-based material 32 can be, for example, a crystalline carbon-based material. The first carbon-based material 32 can be, for example, a carbon nanostructure. The first carbon-based material 32 can be, for example, a two-dimensional carbon nanostructure. The first carbon-based material 32 can be, for example, graphene. For example, the shell comprising graphene and / or its matrix can be flexible, thus readily accepting volume changes in the composite positive electrode active material 100 during battery charging and discharging, thereby suppressing the occurrence of cracks in the composite positive electrode active material 100. Graphene has high electronic conductivity, thus reducing the interfacial resistance between the composite positive electrode active material 100 and the electrolyte. Despite the introduction of a shell containing graphene, the increase in the internal resistance of the lithium battery can be suppressed. Conversely, prior art carbon-based materials that do not contain the first metal oxide 31 tend to aggregate, making it difficult to uniformly distribute them on the core of the dry composite positive electrode active material. Furthermore, the matrix of the first carbon-based material 32 can, for example, be derived from a graphene matrix, and therefore can have a relatively low density and high porosity compared to carbon-based materials derived from graphite materials.

[0062] The composite positive electrode active material 100 may have a mixed structure of a first core 10 / shell 30 and a second core 20 / shell 30. The shell 30 may include a first metal oxide 31, and the metal included in the first metal oxide 31 may be at least one selected from, for example, Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se. The first metal oxide 31 may be, for example, selected from Al₂O₃. 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 SeO [[ID=,23]] y at least one of (0 < y < 2). When the first metal oxide 31 is disposed in the matrix of the first carbonaceous material 32, the uniformity of the shell 30 disposed on the first core 10 or the second core 20 can be improved. Therefore, the high-voltage resistance of the composite positive electrode active material 100 can be further improved. The shell 30 may include, for example, Al2O x (0 < x < 3).

[0063] The shell 30 may further include at least one type of second metal oxide. The second metal oxide may be represented, for example, by the formula M a O c (0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or ɔ, c is an integer), where M may be at least one metal selected from Groups 2 to 13, 15, and 16 of the periodic table. The second metal oxide may include, for example, the same metal as the first metal oxide 31. The ratio c / a of c to a of the second metal oxide may have a value greater than the ratio b / a of b to a of the first metal oxide 31. For example, c / a > b / a. The second metal oxide may be disposed in the matrix of the first carbonaceous material 32. The second metal oxide may be 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 31 may be, for example, a reduced product of the second metal oxide. The first metal oxide 31 may be obtained by partial reduction or complete reduction of the second metal oxide. Therefore, the first metal oxide 31 may have a lower oxygen content and a lower metal oxidation number than the second metal oxide. For example, the shell 30 may include Al2O x (0 < x < 3) as the first metal oxide 31 and Al2O3 as the second metal oxide.

[0064] The shell 30 may include at least one selected from, for example, a first metal oxide and a second metal oxide, and the particle size of at least one selected from the first metal oxide and the second metal oxide may be, for example, 0.1 nm to 100 nm, 0.5 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, 5 nm to 30 nm, or 10 nm to 30 nm. When the first metal oxide 31 and / or the second metal oxide have a particle size in the above nanometer range, the first metal oxide 31 and / or the second metal oxide can be more uniformly distributed in the matrix of the first carbon-based material 32. When the particle size of at least one of the first metal oxide 31 and the second metal oxide increases excessively, the thickness of the shell 30 may increase, and therefore the internal resistance of the composite positive electrode active material 100 may increase. When the particle size of at least one of the first metal oxide 31 and the second metal oxide decreases excessively, uniform dispersion may not be obtained.

[0065] The shell 30 may include a first metal oxide 31 and / or a second metal oxide, and may include a first carbon-based material 32. The first carbon-based material 32 may be arranged in a direction protruding from the surface of the first metal oxide 31 and / or the second metal oxide. The first carbon-based material 32 may be arranged in a direction protruding from the surface of the first metal oxide 31 and / or the second metal oxide by growing directly from the surface of the first metal oxide 31 and / or the second metal oxide. The first carbon-based material 32 arranged in a direction protruding from the surface of the first metal oxide 31 and / or the second metal oxide may be, for example, a two-dimensional carbon nanostructure, a carbon sheet, or graphene.

[0066] The thickness of the shell 30 can be, for example, 0.1 nm to 5 μm, 0.5 nm to 5 μm, 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 50 nm, 1 nm to 30 nm, or 1 nm to 20 nm. When the thickness of the shell 30 is within the above ranges, the electronic conductivity of the dry positive electrode, including the dry composite positive electrode active material, can be further improved, and its internal resistance can be further reduced.

[0067] Based on the total weight of the composite positive electrode active material 100, the content of the shell 30 can be from 0.01 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.01 wt% to 2 wt%, or 0.01 wt% to 1 wt%. Based on the total weight of the composite positive electrode active material 100, the content of the first metal oxide 31 can be from 0.006 wt% to 3 wt%, 0.06 wt% to 1.8 wt%, 0.006 wt% to 1.2 wt%, or 0.006 wt% to 0.6 wt%. When the composite positive electrode active material 100 includes the shell 30 and the first metal oxide 31 within the above ranges, the cycle characteristics of the lithium battery including the composite positive electrode active material can be further improved.

[0068] The shell 30 can have a single-layer or multi-layer structure. A multi-layer structure can include, for example, a two-layer, three-layer, or four-layer structure. The multi-layer structure can contain, for example, different types of metals in the first metal oxide 31 included in each layer.

[0069] The composite positive electrode active material 100 may further include, for example, a third metal doped on the first core 10 or the second core 20, or a third metal oxide coated on the first core 10 or the second core 20. The shell 30 may then be disposed on the third metal doped on the first core 10 or the second core 20, or on the third metal oxide coated on the first core 10 or the second core 20. For example, the shell 30 may be disposed after the third metal is doped onto the surface of a compound (such as a first lithium transition metal oxide or a second lithium transition metal oxide) included in the first core 10 or the second core 20, or after the third metal oxide is coated onto the surface of a compound (such as a first lithium transition metal oxide or a second lithium transition metal oxide) included in the first core 10 or the second core 20. The composite positive electrode active material 100 may include, for example: a core; an intermediate layer disposed on the first core 10 or the second core 20; and a shell 30 disposed on the intermediate layer, wherein the intermediate layer may include the third metal or the third metal oxide. The third metal can be at least one metal selected from Al, Zr, W, and Co, and the third metal oxide can be Al2O3, Li2O-ZrO2, WO2, CoO, Co2O3, Co3O4, or a combination thereof.

[0070] The shell 30 disposed on the surface of the first core 10 or the second core 20 can be, for example, a dry coating. The shell 30 can be introduced onto the first core 10 or the second core 20, for example, by a dry method (such as grinding). The shell 30 disposed on the surface of the first core 10 or the second core 20 can include, for example, at least one of a composite comprising a first metal oxide 31 and a first carbon-based material 32 (such as graphene) and a grinding product of the composite. The first metal oxide 31 can be disposed in a matrix of the first carbon-based material 32 (such as a graphene matrix).

[0071] The shell 30 can be prepared, for example, using a composite comprising a first metal oxide 31 and a first carbon-based material 32 (such as graphene). In addition to the first metal oxide 31, the composite may also include a second metal oxide. The composite may include, for example, at least two types of the first metal oxide 31. The composite may include, for example, at least two types of the first metal oxide 31 and at least two types of the second metal oxide.

[0072] Based on the total weight of the composite positive electrode active material 100, the content of at least one of the composite and its milled products can be, for example, 5 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or 0.5 wt% or less. Based on the total weight of the composite positive electrode active material 100, the content of at least one of the composite and its milled products can be from 0.01 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.01 wt% to 1 wt%, 0.02 wt% to 1 wt%, or 0.05 wt% to 1 wt%. When the dry composite positive electrode active material includes at least one of the composite and its milled products within the above content range, the cycle characteristics of the lithium battery including the dry composite positive electrode active material can be further improved.

[0073] The composite may include at least one selected from a first metal oxide 31 and a second metal oxide. The particle size of at least one selected from the first metal oxide 31 and the second metal oxide may be 0.1 nm to 100 nm, 0.5 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, 5 nm to 30 nm, or 10 nm to 30 nm. When the first metal oxide 31 and / or the second metal oxide has a particle size within the above nanometer range, the first metal oxide 31 and / or the second metal oxide can be more uniformly distributed in the matrix of the first carbon-based material 32 of the composite. Therefore, the composite can be uniformly coated onto the core without aggregation, and then form a shell 30. Furthermore, when the first metal oxide 31 and / or the second metal oxide has a particle size within the above range, the first metal oxide 31 and / or the second metal oxide can be more uniformly distributed on the core. Therefore, by uniformly distributing the first metal oxide 31 and / or the second metal oxide on the core, pressure-resistant properties can be more effectively exhibited. The particle size of the first metal oxide 31 and / or the second metal oxide can be measured, for example, using a measuring device employing laser diffraction or dynamic light scattering. The particle size can be measured, for example, using a laser scattering particle size analyzer (e.g., Horiba Ltd. LA-920), and is the median particle size D50 value when 50% of the particles are accumulated by volume, starting from the smallest particle. The deviation in uniformity of at least one selected from the first metal oxide 31 and the second metal oxide can be 3% or less, 2% or less, or 1% or less. Uniformity can be obtained, for example, by XPS. Therefore, at least one selected from the first metal oxide 31 and the second metal oxide can be uniformly distributed in the composite while having a deviation of 3% or less, 2% or less, or 1% or less.

[0074] The composite may include a first carbon-based material 32. The first carbon-based material 32 may have, for example, a branched structure, and at least one metal oxide selected from a first metal oxide 31 and a second metal oxide may be distributed within this branched structure. The branched structure of the first carbon-based material 32 may include, for example, multiple first carbon-based material particles in contact with each other. When the first carbon-based material 32 has a branched structure, various conductive paths can be provided. The first carbon-based material 32 may be, for example, graphene. Graphene may have, for example, a branched structure, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be distributed within the branched structure of the graphene. The branched structure of the graphene may include, for example, multiple graphene particles in contact with each other. When the graphene has a branched structure, various conductive paths can be provided.

[0075] The first carbon-based material 32 may have, for example, a spherical structure, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be distributed within the spherical structure. The spherical structure of the first carbon-based material 32 may have a size of 50 nm to 300 nm. Multiple first carbon-based materials 32 with spherical structures may be provided. The spherical structure of the first carbon-based material 32 allows the composite to have a rigid structure. The first carbon-based material 32 may be, for example, graphene. Graphene may have, for example, a spherical structure, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be distributed within the spherical structure. The spherical structure of graphene may have a size of 50 nm to 300 nm. Multiple graphenes with spherical structures may be provided. When graphene has a spherical structure, the composite may have a rigid structure.

[0076] The first carbon-based material 32 may have, for example, a helical structure in which multiple spherical structures are interconnected, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be distributed within the spherical structures of the helical structure. The helical structure of the first carbon-based material 32 may have a size of 500 nm to 100 μm. The helical structure of the first carbon-based material 32 may allow the composite to have a rigid structure. The first carbon-based material 32 may be, for example, graphene. Graphene may have, for example, a helical structure in which multiple spherical structures are interconnected, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be distributed within the spherical structures of the helical structure. The helical structure of graphene may have a size of 500 nm to 100 μm. The helical structure of graphene may allow the composite to have a rigid structure.

[0077] The first carbon-based material 32 can have, for example, a cluster structure in which multiple spherical structures are aggregated, and at least one metal oxide selected from a first metal oxide and a second metal oxide can be distributed within the spherical structures of the cluster structure. The cluster structure of the first carbon-based material 32 can have a size of 0.5 mm to 10 cm. The cluster structure of the first carbon-based material 32 can allow the composite to have a rigid structure. The first carbon-based material 32 can be, for example, graphene. Graphene can have, for example, a cluster structure in which multiple spherical structures are aggregated, and at least one metal oxide selected from a first metal oxide and a second metal oxide can be distributed within the spherical structures of the cluster structure. The cluster structure of graphene can have a size of 0.5 mm to 10 cm. The cluster structure of graphene can allow the composite to have a rigid structure.

[0078] The composite may have, for example, a wrinkled, multifaceted spherical structure, and at least one selected from a first metal oxide and a second metal oxide may be distributed within or on the surface of the structure. When the composite has such a multifaceted spherical structure, the composite can be readily applied to the irregular surface irregularities of the core.

[0079] The composite may have, for example, a planar structure, and at least one selected from a first metal oxide and a second metal oxide may be distributed within or on the surface of the structure. When the composite has such a two-dimensional planar structure, the composite can be readily applied to the irregular surface irregularities of the core.

[0080] The first carbon-based material 32 can extend from the first metal oxide by a distance of 10 nm or less, and can include at least one to 20 carbon-based material layers. For example, when multiple first carbon-based material layers are stacked, the first carbon-based material 32 with a total thickness of 12 nm or less can be disposed on the first metal oxide. For example, the total thickness of the first carbon-based material 32 can be within the range of 0.6 nm to 12 nm. The first carbon-based material 32 can be, for example, graphene. Graphene can extend from the first metal oxide by a distance of 10 nm or less, and can include at least one to 20 graphene layers. For example, when multiple graphene layers are stacked, graphene with a total thickness of 12 nm or less can be disposed on the first metal oxide. For example, the total thickness of the graphene can be from 0.6 nm to 12 nm.

[0081] The shell 30 may also include, for example, a second carbon material 33, different from the first carbon material 32. The shell 30 may also include, for example, the second carbon material 33, which is fibrous carbon with an aspect ratio of 10 or greater. Therefore, the conductive path of the composite positive electrode active material can be further extended. The second carbon material 33 forms a three-dimensional conductive network among the multiple composite positive electrode active materials 100 to reduce the internal resistance of the positive electrode including the composite positive electrode active material. When the fibrous carbon is fixed on the composite positive electrode active material 100, a uniform and stable three-dimensional conductive network can be formed among the multiple composite positive electrode active materials 100. Therefore, by including the second carbon material 33 in the composite positive electrode active material 100, the lithium battery including the composite positive electrode active material 100 can have improved high-rate characteristics. On the other hand, a simple mixture of the second carbon material 33, which is fibrous carbon, and the first core 10 or the second core 20 is difficult to form a uniform three-dimensional conductive network among the multiple particles of the first core 10 or the second core 20 due to the aggregation of the fibrous carbon. The second carbon-based material 33 can be disposed on the surface of the composite positive electrode active material 100.

[0082] Reference Figure 2The composite positive electrode active material 100 includes: a first core 10; a second core 20; and a shell 30, arranged continuously or discontinuously along the surface of at least one of the first core 10 and the second core 20. The shell 30 may cover all or part of the first core 10 and the second core 20. The shell 30 may include a first metal oxide 31, a first carbon-based material 32, and a second carbon-based material 33. The second carbon-based material 33 may protrude from the surface of the composite positive electrode active material 100. The second carbon-based material 33 can then effectively provide a conductive network among the plurality of composite positive electrode active materials 100. When the second carbon-based material 33 is disposed in the matrix of the first carbon-based material 32, the second carbon-based material 33 can be readily applied to the first core 10 or the second core 20. The matrix of the first carbon-based material 32 can be used as an adhesive to bond the second carbon-based material 33 to the first core 10 or the second core 20. Therefore, in the absence of a matrix of the first carbon-based material 32, the second carbon-based material 33 may not easily adhere to the first core 10 or the second core 20 during the preparation process of the slurry used for the positive electrode, or the second carbon-based material 33 may easily detach from the first core 10 or the second core 20. When an additional binder is added to bond the second carbon-based material 33 to the first core 10 or the second core 20, the first core 10 or the second core 20 may be coated with an insulating binder, thereby increasing the internal resistance of the composite positive electrode active material 100. In order to carbonize the binder, when the core coated with the second carbon-based material 33 and the binder is subjected to heat treatment at high temperature, the first core 10, the second core 20, and the second carbon-based material 33 may deteriorate during the heat treatment process.

[0083] Here, the second carbon-based material 33 may have an aspect ratio of 10 or greater, or 20 or greater. The aspect ratio of the second carbon-based material 33 may be, for example, 10 to 100,000, 10 to 80,000, 10 to 50,000, 10 to 10,000, 10 to 5000, 10 to 100, 10 to 500, 10 to 100, or 10 to 50. The aspect ratio of the second carbon-based material 33 may be, for example, the ratio of the length of the major axis (e.g., the length of the second carbon-based material 33 passing through the center of the second carbon-based material 33) to the length of the minor axis (e.g., the diameter of the second carbon-based material 33 passing through the center of the second carbon-based material 33 and perpendicular to the major axis).

[0084] The diameter of the second carbon-based material 33 can be, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. The diameter of the second carbon-based material 33 can be, for example, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. When the diameter of the second carbon-based material 33 is too large, the absolute number of strands per volume may decrease, and therefore the effect of reducing internal resistance may not be significant. When the diameter of the second carbon-based material 33 is too small, uniform dispersion may be difficult.

[0085] The length of the second carbon-based material 33 can be, for example, 1000 μm or less, 100 μm or less, 50 μm or less, 10 μm or less, 5 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. The length of the second carbon-based material 33 can be, for example, 100 nm to 1000 μm, 100 nm to 500 μm, 100 nm to 100 μm, 100 nm to 50 μm, 100 nm to 10 μm, 100 nm to 5 μm, 100 nm to 2 μm, 100 nm to 1 μm, 100 nm to 500 nm, or 100 nm to 300 nm. The length of the second carbon-based material 33 can be, for example, 500 nm to 1000 μm, 500 nm to 500 μm, 500 nm to 100 μm, 500 nm to 50 μm, 500 nm to 10 μm, 500 nm to 5 μm, or 500 nm to 2 μm. As the length of the second carbon-based material 33 increases, the internal resistance of the electrode can decrease. When the length of the second carbon-based material 33 is too short, it may not be able to provide an effective conductive path.

[0086] The second carbon-based material 33 may include, for example, carbon nanofibers, carbon nanotubes, or combinations thereof.

[0087] Carbon nanotubes can include, for example, primary carbon nanotube structures, secondary carbon nanotube structures formed by the aggregation of multiple particles of primary carbon nanotube structures, or combinations thereof.

[0088] Primary carbon nanotube structures can be single carbon nanotube units. These units can comprise cylindrical graphite sheets with nanometer-sized diameters and can exhibit sp2 hybridization. Depending on the curvature and structure of the graphite sheet, they can exhibit conductive or semiconductor properties. Based on the number of bonds forming the walls, carbon nanotube units can be classified as single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), etc. Because of the small wall thickness of carbon nanotube structural units, electrical resistance can be reduced.

[0089] Primary carbon nanotube structures can include, for example, SWCNTs, DWCNTs, MWCNTs, or combinations thereof. The diameter of the primary carbon nanotube structure can be, for example, 1 nm or greater, or 2 nm or greater. The diameter of the primary carbon nanotube structure can be, for example, 20 nm or less, or 10 nm or less. The diameter of the primary carbon nanotube structure can be, for example, 1 nm to 20 nm, 1 nm to 15 nm, or 1 nm to 10 nm. The length of the primary carbon nanotube structure can be, for example, 100 nm or greater, or 200 nm or greater. The length of the primary carbon nanotube structure can be, for example, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. The length of the primary carbon nanotube structure can be, for example, 100 nm to 2 μm, 100 nm to 1 μm, 100 nm to 500 nm, 100 nm to 400 nm, 100 nm to 300 nm, or 200 nm to 300 nm. The diameter and length of the primary carbon nanotube structure can be measured by scanning electron microscopy (SEM) images or transmission electron microscopy (TEM) images. Alternatively, the diameter and / or length of the primary carbon nanotube structure can be measured by laser diffraction.

[0090] Secondary carbon nanotube structures can be formed by assembling primary carbon nanotube structures integrally or partially in bundles or clusters. Secondary carbon nanotube structures can include, for example, bundled carbon nanotubes, rope-like carbon nanotubes, or combinations thereof. The diameter of the secondary carbon nanotube structure can be, for example, 2 nm or greater, or 3 nm or greater. The diameter of the secondary carbon nanotube structure can be, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. The diameter of the secondary carbon nanotube structure can be, for example, 2 nm to 50 nm, 2 nm to 30 nm, or 2 nm to 20 nm. The length of the secondary carbon nanotube structure can be, for example, 500 nm or greater, 700 nm or greater, 1 μm or greater, or 10 μm or greater. The length of the secondary carbon nanotube structure can be, for example, 1000 μm or less, 500 μm or less, or 100 μm or less. The length of the secondary carbon nanotube structure can be, for example, 500 nm to 1000 μm, 500 nm to 500 μm, 500 nm to 200 μm, 500 nm to 100 μm, or 500 nm to 50 μm. The diameter and length of the secondary carbon nanotube structure can be measured by SEM images or optical microscope images. Alternatively, the diameter and / or length of the secondary carbon nanotube structure can be measured by laser diffraction.

[0091] Secondary carbon nanotube structures can be dispersed in a solvent, for example, to convert them into primary carbon nanotube structures, which can then be used to manufacture composite positive electrode active material 100.

[0092] Based on the total weight of the first carbon-based material 32 and the second carbon-based material 33, the content of the second carbon-based material 33 can be, for example, from 0.1 wt% to 50 wt%, from 1 wt% to 40 wt%, or from 5 wt% to 30 wt%. When the composite positive electrode active material 100 includes the first carbon-based material 32 and the second carbon-based material 33 within the above range, the conductive path can be further effectively ensured in the composite positive electrode active material 100, thereby further reducing the internal resistance of the composite positive electrode active material 100. Therefore, the cycle characteristics of the lithium battery including the composite positive electrode active material 100 can be further improved. Based on the total weight of the composite positive electrode active material 100, the content of the second carbon-based material 33 can be, for example, from 0.001 wt% to 5 wt%, from 0.01 wt% to 3 wt%, from 0.01 wt% to 1 wt%, from 0.01 wt% to 0.5 wt%, or from 0.01 wt% to 0.1 wt%. When the composite positive electrode active material 100 includes a second carbon-based material 33 within the above-mentioned range, a conductive path can be ensured in the composite positive electrode active material 100, thereby further reducing the internal resistance of the composite positive electrode active material 100. Therefore, the cycle characteristics of lithium batteries including the composite positive electrode active material 100 can be further improved.

[0093] The shell 30 may include a first metal oxide 31 and a first carbon-based material 32, the first core 10 may include a first lithium transition metal oxide, and the second core 20 may include a second lithium transition metal oxide. The first carbon-based material 32 may be chemically bonded to the transition metal of the first or second lithium transition metal oxide via, for example, chemical bonds. The carbon atoms (C) of the first carbon-based material 32 may be chemically bonded to the transition metal (Me) of the first or second lithium transition metal oxide via, for example, oxygen-mediated CO-Me bonds (e.g., CO-Ni or CO-Co bonds). When the first carbon-based material 32 disposed in the shell 30 is chemically bonded to the first lithium transition metal oxide disposed in the first core or the second lithium transition metal oxide disposed in the second core via chemical bonds, the shell 30 may form a complex with the first core 10 or the second core 20. Therefore, the composite positive electrode active material 100 is different from a simple physical mixture or blend of the first carbon-based material 32 and the first and / or second lithium transition metal oxides. The first metal oxide and the first carbon-based material 32 can also be chemically bonded. Here, the chemical bond can be, for example, a covalent bond or an ionic bond.

[0094] [Positive electrode] According to another embodiment, the positive electrode includes: a positive electrode current collector; and a positive electrode active material layer on one or both sides of the positive electrode current collector, and includes a composite positive electrode active material.

[0095] [Positive electrode: Positive electrode current collector] The positive electrode current collector may include, for example, a metal layer.

[0096] The material constituting the metal layer can be a material that does not react with lithium, that is, any metal or alloy that is conductive and does not form an alloy or compound with lithium. The metal layer can be composed of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof. The metal layer can have shapes selected from, but not limited to, sheets, foils, films, plates, porous bodies, mesoporous bodies, bodies with through holes, polygonal rings, meshes, foams, and nonwovens. Any shape available in the art can be used.

[0097] The positive electrode current collector may include, for example, a substrate film and a metal layer disposed on one or both sides of the substrate film. The substrate film may include, for example, a polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or combinations thereof. The metal layer may include, for example, In, Cu, Mg, stainless steel, Ti, Fe, Co, Ni, Zn, Al, Ge, Li, or alloys thereof. When the positive electrode current collector has the above structure, the weight of the electrode can be reduced, thereby improving the energy density of the all-solid-state secondary battery.

[0098] The positive electrode current collector may include, for example, a metal layer; and an intermediate layer disposed between the metal layer and the positive electrode active material layer. The intermediate layer may include, for example, a carbon-based conductive material.

[0099] The intermediate layer can be disposed, for example, directly on one or both sides of the metal layer. Therefore, no other layer needs to be disposed between the metal layer and the intermediate layer. When the intermediate layer is disposed directly on one or both sides of the metal layer, the adhesion between the metal layer and the positive electrode active material layer can be further improved.

[0100] Depending on the thickness of the metal layer, the thickness of the intermediate layer can be, for example, 0.01% to 30%, 0.1% to 30%, 0.5% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, 1% to 5%, or 1% to 3%. The thickness of the intermediate layer can be, for example, 10 nm to 5 μm, 50 nm to 5 μm, 200 nm to 4 μm, 500 nm to 3 μm, 500 nm to 2 μm, 500 nm to 1.5 μm, or 700 nm to 1.3 μm. When the thickness of the intermediate layer is within the above ranges, the adhesion between the metal layer and the positive electrode active material layer can be further improved, and the increase in interfacial resistance can be suppressed.

[0101] The intermediate layer may include, for example, a carbon-based conductive material. The carbon-based conductive material included in the intermediate layer may be selected from the carbon-based conductive materials included in the positive electrode active material layer. The intermediate layer may include the same carbon-based conductive material as that included in the positive electrode active material layer. When the intermediate layer includes a carbon-based conductive material, the intermediate layer may serve as, for example, a conductive layer.

[0102] The intermediate layer may also include, for example, an adhesive. When the intermediate layer also includes an adhesive, the adhesion between the metal layer and the positive electrode active material layer can be further improved. The adhesive included in the intermediate layer can be, for example, a conductive adhesive or a non-conductive adhesive. The conductive adhesive can be, for example, an ionicly conductive adhesive and / or an electronically conductive adhesive. An adhesive having both ionic and electronic conductivity can be classified as either an ionicly conductive adhesive or an electronically conductive adhesive.

[0103] The binder included in the intermediate layer can be, for example, selected from the binder included in the positive electrode active material layer. The intermediate layer can include the same binder as that included in the positive electrode active material layer. The binder included in the intermediate layer can be, for example, a fluorinated binder. The fluorinated binder included in the intermediate layer can be, for example, PVDF. The intermediate layer can be, for example, a bonding layer including a binder. The intermediate layer can be, for example, a conductive layer including both a binder and a carbon-based conductive material.

[0104] The intermediate layer can be disposed on the metal layer, for example, by a dry or wet method. The intermediate layer can be disposed on the metal layer by a dry method, such as by deposition using CVD, PVD, etc. The intermediate layer can be disposed on the metal layer by a wet method, such as by spin coating, dip coating, etc. The intermediate layer can be disposed on the metal layer, for example, by depositing a carbon-based conductive material onto the metal layer. A dry-coated intermediate layer can consist of a carbon-based conductive material and may not include a binder. The intermediate layer can be disposed on the metal layer, for example, by coating the surface of the metal layer with a composition including a carbon-based conductive material, a binder, and a solvent, and then drying the resulting surface. The intermediate layer can have a single-layer structure or can be a multilayer structure comprising multiple layers. The multilayer structure can be a two-layer, three-layer, or four-layer structure.

[0105] For example, the positive electrode can be a dry positive electrode or a wet positive electrode.

[0106] The positive electrode active material layer included in the dry positive electrode can be manufactured by a dry manufacturing method, and the positive electrode active material layer including the composite positive electrode active material having the aforementioned core / shell structure can be a dry positive electrode film. When the positive electrode includes a dry positive electrode film, the internal resistance of the dry positive electrode can be reduced, thereby improving its mechanical properties. The dry positive electrode film can be deposited on the positive electrode current collector by a lamination process.

[0107] [Positive electrode: Dry positive electrode] The dry positive electrode film may include a dry binder. The dry binder may be, for example, a binder that is not impregnated, dissolved, or dispersed in a processing solvent during the process of manufacturing the dry positive electrode film. The dry binder may be, for example, a binder that does not include a processing solvent or is not in contact with a processing solvent during the process of manufacturing the dry positive electrode film. The dry binder may be, for example, a fibrillated binder or a fibrous binder. The fibrillated binder or fibrous binder can be used as a matrix to support the electrode active material included in the electrode active material layer and to bond it to other components. The fibrillated binder or fibrous binder may be identified as having a fibrous form, for example, by SEM images of a cross-section of the electrode. The fibrillated binder or fibrous binder may have an aspect ratio of, for example, 10 or greater, 20 or greater, 50 or greater, or 100 or greater.

[0108] Examples of dry binders include, but are not limited to, PTFE, PVDF-HFP copolymers, PVDF, polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, cellulose, polyvinylpyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, copolymers thereof, etc. Any binder used in the manufacture of dry positive electrodes can be used. Dry binders may specifically include fluorinated binders. Fluorinated binders can be, for example, PTFE, PVDF-HFP copolymers, or PVDF.

[0109] Glass transition temperature (T) of dry adhesive g The temperature range can be, for example, -30°C to 150°C, 15°C to 150°C, 15°C to 130°C, 50°C to 130°C, 100°C to 130°C, or 120°C to 130°C. The glass transition temperature T of the dry adhesive... g The glass transition temperature (Tg) of PTFE can be, for example, -30°C to 150°C, -30°C to 100°C, -30°C to 50°C, -30°C to 15°C, -30°C to -10°C, or -30°C to -20°C. g The temperature can be, for example, 120°C to 130°C. When the glass transition temperature (T) of the dry adhesive... g When the above range is met, fibrillated binders or fibrous binders can be more easily obtained in the process of manufacturing dry positive electrodes.

[0110] Based on the total weight of the dry positive electrode film, the content of the dry binder can be, for example, 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, or 1 wt% to 5 wt%. When the dry positive electrode film includes a dry binder within the above content range, the adhesion of the dry positive electrode film can be improved, and the dry positive electrode film can maintain a high energy density.

[0111] The dry positive electrode film may also include, for example, a dry conductive material. The dry conductive material may be, for example, a conductive material that is not impregnated, dissolved, or dispersed in a processing solvent during the process of manufacturing the dry positive electrode film. The dry conductive material may be, for example, a conductive material that does not include a processing solvent or is not in contact with a processing solvent during the process of manufacturing the dry positive electrode film. The dry conductive material may be, for example, a carbon-based conductive material. The carbon-based conductive material may include, for example, fibrous carbon materials having an aspect ratio of 10 or greater, particulate carbon materials having an aspect ratio of less than 10, or combinations thereof.

[0112] Examples of fibrous carbon materials with an aspect ratio of 10 or greater include, but are not limited to, carbon fibers, carbon nanotubes, carbon nanoribbons, etc. Any material in the art that can be used as a carbon-based conductive material can be used. The fibrous carbon material with an aspect ratio of 10 or greater can be selected from second-class carbon materials. The fibrous carbon material can be distinguished from the second-class carbon material constituting part of the composite positive electrode active material simply by mixing it with the composite positive electrode active material.

[0113] Examples of carbon-based materials with an aspect ratio less than 10 include, but are not limited to, carbon black, acetylene black, Ketjen black, natural graphite, and synthetic graphite. Any material in the art that can be used as a carbon-based conductive material can be used. The aspect ratio of particulate carbon materials can be, for example, 1 to 7, 1 to 5, 1 to 3, or 1 to 2.

[0114] Based on the total weight of the dry positive electrode film, the content of dry conductive material included in the dry positive electrode film can be, for example, 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, or 1 wt% to 5 wt%. When the dry positive electrode film includes dry conductive material within the above content range, the conductivity of the dry positive electrode film can be improved, thereby improving the cycle characteristics of the lithium battery including the dry positive electrode film.

[0115] Dry positive electrode membranes can be, for example, self-standing membranes. Dry positive electrode membranes can maintain their shape, for example, without a support. Therefore, dry positive electrode membranes can be prepared as separate self-standing membranes and then arranged on a positive electrode current collector. Dry positive electrode membranes are manufactured in a drying process, and therefore may not contain intentionally added processing solvents. For example, dry positive electrode membranes may not contain residual processing solvents. Unintended trace amounts of solvent may remain in dry positive electrode membranes, but these solvents are not intentionally added processing solvents. Therefore, dry positive electrode membranes can be distinguished from wet electrode membranes prepared by mixing components with a processing solvent and then removing some or all of the processing solvent by drying.

[0116] The tensile strength of the dry positive electrode film at 25°C can be, for example, 500 kPa or greater, 700 kPa or greater, or 1000 kPa or greater. The tensile strength of the dry positive electrode film at 25°C can be, for example, 500 kPa to 5000 kPa, 700 kPa to 5000 kPa, or 1000 kPa to 5000 kPa. When the dry positive electrode film has a tensile strength within the above range, the structural stability of the dry positive electrode film can be improved. Therefore, during charging and discharging processes, the dry positive electrode film can improve the reversibility of the electrode reaction while maintaining a stable three-dimensional conductive network. When the dry positive electrode film has a high tensile strength within the above range, the mechanical strength of the dry positive electrode film can be improved. Due to the improved mechanical strength of the dry positive electrode film, localized degradation caused by volume changes during charging and discharging of the electrode including the dry electrode film and the lithium battery including the electrode can be suppressed. Therefore, the cycle characteristics of the lithium battery can be improved.

[0117] [Positive electrode: Wet positive electrode] The positive electrode active material layer included in the wet positive electrode can be manufactured by a wet manufacturing method, and can be a wet positive electrode active material layer including a composite positive electrode active material. For example, a wet positive electrode active material layer can be disposed on the positive electrode current collector by applying a composition including a composite positive electrode active material having the aforementioned core / shell structure, a wet binder, a wet conductive material, and a solvent to the surface of the positive electrode current collector, and then drying the composition.

[0118] Examples of wet conductive materials are: carbon black, graphite particles, natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fibers; carbon nanotubes; metal powders, metal fibers, or metal tubes of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives, etc., but not limited thereto. Any material that can be used as a conductive material in the art can be used.

[0119] Examples of wet adhesives are vinylidene fluoride / hexafluoropropylene copolymers, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, PTFE, mixtures of the aforementioned polymers, styrene-butadiene rubber polymers, etc. Examples of solvents are N-methylpyrrolidone (NMP), acetone, water, etc. However, the examples are not limited to these, and any material that can be used as a wet adhesive and solvent in the art can be used.

[0120] Plasticizers or pore-forming agents can be added to the positive electrode active material composition to form pores inside the positive electrode active material layer.

[0121] The content of the composite positive electrode active material, wet conductive material, wet binder, and solvent used in the wet positive electrode can be at a level suitable for lithium batteries in the art. Depending on the application and construction of the lithium battery, at least one of the wet conductive material, wet binder, and solvent may be omitted.

[0122] Based on the total weight of the positive electrode active material layer, the content of the wet binder included in the wet positive electrode can be from 0.1 wt% to 10 wt% or from 0.1 wt% to 5 wt%. Based on the total content of the composite positive electrode active material layer, the content of the composite positive electrode active material included in the wet positive electrode can be from 90 wt% to 99 wt% or from 95 wt% to 99 wt%.

[0123] The composite positive electrode active material includes: a first core and a second core, each of the first core and the second core comprising a first lithium transition metal oxide and a second lithium transition metal oxide; and a shell disposed on the surface of the first core or the surface of the second core, comprising a first metal oxide and a first carbon-based material.

[0124] In addition to the dry composite positive electrode active material having a core / shell structure, the positive electrode active material layer may also include a general positive electrode active material. For the general positive electrode active material used as a further addition, any material available in the art as a positive electrode active material can be used without limitation.

[0125] The positive electrode active material can be, for example, a composite oxide of lithium with at least one metal selected from Co, Mn, Ni, and combinations thereof, and specific examples of the composite oxide are compounds represented by one of the following formulas: Li a A 1-b B b D2 (0.90≤a≤1, and 0≤b≤0.5); Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, and 0≤c≤0.05); LiE 2-b B b O 4-c D c (0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α≤2); Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni 1-b-c Cob B c O 2-α F2 (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni 1-b- c Mn b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α≤2); Li a Ni 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni 1-b-c Mn b B c O 2-α F2 (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni b E c G d O2 (0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, and 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2 (0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0.001≤e≤0.1); Li a NiG b O2 (0.90≤a≤1, and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1, and 0.001≤b≤0.1); Li a MnG b O2 (0.90≤a≤1, and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1, and 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3 (0≤f≤2); Li (3-f)Fe2(PO4)3 (0≤f≤2); and LiFePO4.

[0126] In the above formula representing compounds, A can be Ni, Co, Mn or a combination thereof; B can be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D can be O, F, S, P or a combination thereof; E can be Co, Mn or a combination thereof; F can be F, S, P or a combination thereof; G can be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q can be Ti, Mo, Mn or a combination thereof; I can be Cr, V, Fe, Sc, Y or a combination thereof; J can be V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0127] Compounds in which a coating is further formed on the surface of the aforementioned compounds can also be used, and mixtures of the aforementioned compounds and compounds with a further coating can also be used. The coating formed on the surface of the compound can include, for example, a coating element compound, such as an oxide of the coating element, a hydroxide of the coating element, a hydroxy oxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element. The compound constituting the coating can be amorphous or crystalline. The coating element included in the coating can be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method of forming the coating can be selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method can be, for example, spraying, dipping, etc. A detailed description of the coating method will be omitted, as it will be well understood by those skilled in the art.

[0128] [Lithium battery] A lithium battery according to another embodiment may include: a positive electrode; a negative electrode; and an electrolyte disposed between the positive electrode and the negative electrode.

[0129] The cycle characteristics of lithium batteries can be improved when they include a positive electrode with reduced internal resistance and improved mechanical properties.

[0130] A lithium battery may include, for example, a dry positive electrode, a dry negative electrode, or both a dry positive electrode and a dry negative electrode. A lithium battery may also include, for example: a dry positive electrode and a wet negative electrode; a dry positive electrode and a dry negative electrode; a wet positive electrode and a dry negative electrode; or a wet positive electrode and a wet negative electrode.

[0131] [Lithium-ion battery: electrolyte] Lithium batteries include an electrolyte, and the electrolyte may include, for example, a liquid electrolyte, a solid electrolyte, or a combination thereof.

[0132] The electrolyte (e.g., a liquid electrolyte) can be, for example, an organic electrolyte. Organic electrolytes can be prepared, for example, by dissolving a lithium salt in an organic solvent.

[0133] For use as an organic solvent, any material available in the art as an organic solvent may be used. Examples of organic solvents are propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzyl nitrile, 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 mixtures thereof. The organic solvent may be, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzyl nitrile, 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 mixtures thereof.

[0134] For use as a lithium salt, any material that can be used as a lithium salt in the art can be used. Lithium salts can be, for example, 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), LiCl, LiI, or mixtures thereof.

[0135] Solid electrolytes may include, for example, inorganic solid electrolytes, organic solid electrolytes, organic-inorganic composite solid electrolytes, or combinations thereof.

[0136] Solid electrolytes may include, for example, oxide solid electrolytes, sulfide solid electrolytes, polymer solid electrolytes, or combinations thereof.

[0137] Examples of solid electrolytes are boron oxide, lithium oxynitride, etc., but are not limited thereto. Any suitable solid electrolyte available in the art can be used. Solid electrolytes can be formed on the negative electrode, for example, by sputtering or the like, or separate solid electrolyte sheets can be stacked on the negative electrode.

[0138] An example of an 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≤1, 0≤y≤1), Li x La y TiO3 (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, 0≤x≤10), Li 3+ x La3Zr 2-y M y O 12 (M-doped LLZO, M = Ga, W, Nb, Ta, Al or a combination thereof, 0 ≤ x ≤ 10, 0 <y<2)、Li7La3Zr 2-x Ta xO 12 (0 < x < 2, LLZ-Ta) or combinations thereof. The oxide-based solid electrolyte can be, for example, a garnet-type solid electrolyte. The oxide-based solid electrolyte can be manufactured by a sintering method or the like.

[0139] Examples of the oxide-based solid electrolyte are Li7La3Zr2O 12 (LLZO), Li 6.5 La3Zr 1.5 Ta 0.5 O 12 、Li 1.3 Al 0.3 Ti 1.7 (PO4)3、Li 0.34 La 0.51 TiO 2.94 、Li 1.07 Al 0.69 Ti 1.46 (PO4)3、50Li4SiO4 - 50Li2BO3、90Li3BO3 - 10Li2SO4、Li 2.9 PO 3.3 N 0.46 or combinations thereof.

[0140] The sulfide-based solid electrolyte can include, for example, one or more selected from the following: Li2S - P2S5, Li2S - P2S5 - LiX (X is a halogen atom), 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 (where m and n are positive numbers, and Z is one of Ge, Zn, and Ga), Li2S - GeS2, Li2S - SiS2 - Li3PO4, Li2S - SiS2 - Li p MO q (p and q are positive numbers, and M is P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (0 ≤ x ≤ 2) and Li 7-x PS 6-x I x(0≤x≤2). Sulfide-based solid electrolytes can be prepared, for example, by treating starting materials such as Li₂S, P₂S₅, etc., via melt quenching or mechanical grinding. After such treatment, they can then be heat-treated. Sulfide-based solid electrolytes can be amorphous, crystalline, or in a mixed state.

[0141] Sulfide solid electrolytes may include, for example, sulfide-germanium ore type solid electrolytes represented by Formula 9: Formula 9 Li + 12-n-x A n+ X 2- 6-x Y - x In the formula, A can be P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta; X can be S, Se, or Te; Y can be Cl, Br, I, F, CN, OCN, SCN, or N3; 1≤n≤5; and 0≤x≤2.

[0142] Sulfide solid electrolytes can be sulfide-based compounds including at least one of the following: Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (Where, 0≤x≤2). Specifically, the sulfide-based solid electrolyte included in the solid electrolyte can be a sulfosilver-germanium ore type compound including at least one selected from Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0143] Polymer solid electrolytes can be, for example, solid electrolytes comprising ion-conducting polymers and lithium salts, solid electrolytes comprising polymer ionic liquids and lithium salts, or combinations thereof.

[0144] Ion-conducting polymers can be polymers that include ion-conducting repeating units in their main chain or side chains. These repeating units can be ionically conductive units and can be, for example, epoxy alkyl units or hydrophilic units. Examples of ion-conducting polymers are polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethyl methacrylate, polyethyl methacrylate, 2-ethylhexyl polyacrylate, polybutyl methacrylate, 2-ethylhexyl polymethacrylate, decyl polyacrylate, polyvinyl acetate, or combinations thereof. Ion-conducting polymers can also be, for example, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinyl sulfone, or combinations thereof.

[0145] Polymer ionic liquids (PILs) may include, for example, repeating units, said repeating units comprising: i) at least one cation selected from ammonium cations, pyrrolidineonium cations, pyridinium cations, pyrimidineonium cations, imidazolium cations, piperidinium cations, pyrazolium cations, oxazolium cations, pyridazineonium cations, phosphonium cations, sulfonium cations, triazole cations, and mixtures thereof; ii) at least one anion selected from BF4. - PF6 - AsF6 - SbF6 - AlCl4 - HSO4 - ClO4 - CH3SO3 - CF3CO2 - (CF3SO2)2N - Cl - ,Br - I - BF4 - SO4 - PF6 - ClO4 - CF3SO3 - CF3CO2 - (C2F5SO2)2N - (C2F5SO2)(CF3SO2)N - NO3 - Al2Cl7 - AsF6 - SbF6 - CF3COO - CH3COO - CF3SO3 - (CF3SO2)3C -(CF3CF2SO2)2N - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - SF5CF2SO3 - SF5CHFCF2SO3 - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - 、(O(CF3)2C2(CF3)2O)2PO - and (CF3SO2)2N - PIL can be, for example, poly(diallyldimethylammonium)(trifluoromethanesulfonyl)imide (poly(diallyldimethylammonium)TFSI), poly(1-allyl-3-methylimidazolium trifluoromethanesulfonylimide), poly(N-methyl-N-propylpiperidine bis(trifluoromethanesulfonyl)imide) or combinations thereof.

[0146] Lithium salts can be, for example, 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 (1≤x≤20 and 1≤y≤20), LiCl, LiI, or combinations thereof.

[0147] [Dry Positive Electrode: Manufacturing Method] Another embodiment provides a method for manufacturing a dry positive electrode.

[0148] A method for manufacturing a dry positive electrode includes: providing a dry positive electrode film; and arranging the dry positive electrode film on one or both sides of a positive electrode current collector.

[0149] Providing a dry positive electrode film may include: dry mixing the aforementioned composite positive electrode active material, dry conductive material and dry binder to prepare a dry mixture; and molding the dry mixture to prepare a dry positive electrode film.

[0150] First, the aforementioned composite positive electrode active material, dry conductive material, and dry binder are dry-mixed to prepare a dry mixture. For example, a dry mixture containing the composite positive electrode active material, dry conductive material, and dry binder is prepared.

[0151] Dry mixing refers to mixing without the use of a processing solvent. A processing solvent refers to a solvent used, for example, in the preparation of the electrode slurry. The processing solvent can be, for example, water, NMP, etc., but is not limited to these. Any processing solvent used in the preparation of the electrode slurry can be used without limitation. Dry mixing can be performed, for example, at a temperature of 15°C to 65°C and a speed of 10 rpm to 10,000 rpm using a stirrer. Dry mixing can be performed, for example, using a stirrer for 1 minute to 200 minutes.

[0152] Dry mixing can be performed at least once. First, a first dry mixture can be prepared by first dry mixing the composite positive electrode active material, the dry conductive material, and the dry binder. The first dry mixing can be performed, for example, at a temperature of 25°C to 65°C and a rotation speed of 10 rpm to 2000 rpm for 15 minutes or less. Subsequently, a second mixture can be prepared by further dry mixing the first dry mixture. The second dry mixing can be performed, for example, at a temperature of 25°C to 65°C and a rotation speed of 3000 rpm to 9000 rpm for 10 minutes to 60 minutes. Through the second dry mixing, a dry mixture including a fibrillated dry binder can be obtained.

[0153] The mixer can be, for example, a kneader. The mixer may include, for example, a chamber; at least one rotating shaft disposed inside the chamber for rotation; and blades rotatably coupled to the rotating shaft and arranged in the longitudinal direction of the rotating shaft. The blades can be, for example, at least one selected from ribbon blades, sigma blades, jet (Z) blades, dispersing blades, and helical blades. When blades are included, a dough-like mixture can be prepared by effectively mixing the composite positive electrode active material, the dry conductive material, and the dry binder.

[0154] Examples of dry binders include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), mixtures of the above polymers, styrene-butadiene rubber polymers, etc. The dry binder can be selected from those used in dry positive electrode films.

[0155] Examples of dry conductive materials are: carbon black, graphite particles, natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fibers; carbon nanotubes; metal powders, metal fibers, or metal tubes of copper, nickel, aluminum, silver, etc.; and conductive polymers, such as, but not limited to, polyphenylene derivatives. Any suitable binder available in the art can be used. The conductive material can be, for example, a carbon-based conductive material. The dry conductive material can be selected from dry conductive materials used for dry positive electrode films.

[0156] Plasticizers or pore-forming agents can also be added to the dry mixture to form pores inside the electrode plate.

[0157] The content of composite positive electrode active material, dry binder and dry conductive material used in the dry positive electrode film can be at a level suitable for lithium batteries in this field.

[0158] Dry positive electrode membranes can use composite positive electrode active materials having a first core / shell structure and / or a second core / shell structure as composite positive electrode active materials. The description of composite positive electrode active materials is the same as described above. Dry negative electrode membranes can use dry negative electrode active materials as negative electrode active materials.

[0159] The dry mixture can then be shaped to prepare a dry positive electrode film.

[0160] The prepared dry mixture can be introduced into an extrusion apparatus and extruded in sheet or film form. The extrusion pressure can be, for example, from 4 MPa to 100 MPa.

[0161] Next, an electrode current collector in which the intermediate layer is arranged on one or both sides of the metal layer can be provided.

[0162] Providing an electrode current collector in which an intermediate layer is disposed on one or both sides of a metal layer may, for example, include: providing a metal layer; and disposing an intermediate layer on one or both sides of the metal layer.

[0163] The description of the metal layer of the positive electrode current collector is the same as described above for the positive electrode current collector. The metal layer of the positive electrode current collector can be, for example, aluminum foil. The negative electrode current collector can be, for example, copper foil.

[0164] Depositing an intermediate layer on one or both sides of a metal layer can include dry coating and / or wet coating. Dry coating can, for example, be coating one or both sides of the positive electrode current collector with a carbon-based conductive material and / or its precursor. Dry coating can be performed at room temperature to high temperature or at atmospheric pressure to vacuum. When the intermediate layer disposed by dry coating consists of a carbon-based conductive material, the intermediate layer may not include a binder. By wet coating, a composition comprising a carbon-based conductive material and a binder can, for example, be applied to one or both sides of the positive electrode current collector. The composition may include, for example, a carbon-based conductive material, a binder, and a processing solvent. The description of the carbon-based conductive material and the binder refers to the description of the positive electrode. The processing solvent may be selected from solvents used to prepare the positive electrode slurry. After the composition is applied to the positive electrode current collector, the processing solvent can be removed by drying. Examples of coating methods are spin coating, dip coating, etc., but are not limited thereto. Any coating method available in the art can be used.

[0165] Next, the dry positive electrode film can be arranged simultaneously or sequentially on one or both sides of the positive electrode current collector to manufacture the dry positive electrode.

[0166] A rolling process can be added during and / or after the dry positive electrode film is arranged on one or both sides of the positive electrode current collector.

[0167] Examples of rolling processes include roller presses and flatbed presses, but are not limited to these. The rolling pressure can be, for example, 1.0 ton / cm². 2 Up to 10.0 tons / cm 2 When the rolling pressure is excessively high, the positive electrode current collector may rupture. When the rolling pressure is too low, the adhesion between the positive electrode current collector and the dry positive electrode film may decrease.

[0168] [Wet Positive Electrode: Manufacturing Method] Another embodiment provides a method for manufacturing a wet positive electrode.

[0169] The method for manufacturing a wet positive electrode includes: preparing a positive electrode active material slurry by mixing a composite positive electrode active material, a wet conductive material, a wet binder, and a solvent; directly coating a positive electrode current collector with the prepared positive electrode active material slurry; and drying the positive electrode current collector coated with the positive electrode active material slurry to form a positive electrode active material layer and a wet positive electrode.

[0170] Alternatively, the positive electrode active material slurry can be cast onto a separate support, and then the film layer obtained by peeling off the support can be pressed onto the positive electrode current collector to produce a wet positive electrode on which the positive electrode active material layer is formed.

[0171] The description of the composite positive electrode active material, wet conductive material, wet binder and solvent included in the positive electrode active material slurry is the same as that of the wet positive electrode.

[0172] [Lithium-ion batteries: Manufacturing methods] Lithium batteries are manufactured using the example methods described below; however, embodiments of this disclosure are not necessarily limited to this method and may be modified to suit desired conditions.

[0173] First, according to the dry electrode manufacturing method, one or both of a positive electrode and a negative electrode can be manufactured. Optionally, when one of the positive and negative electrodes is manufactured by the dry electrode manufacturing method, the other electrode can be manufactured by the wet electrode manufacturing method. For example, the other electrode can be manufactured by preparing an electrode slurry comprising an electrode active material, a conductive material, a binder, and a solvent, and coating an electrode current collector with the prepared electrode slurry. The prepared dry or wet positive electrode may include the aforementioned composite positive electrode active material.

[0174] Next, a diaphragm to be inserted between the positive and negative electrodes can be prepared.

[0175] The separator can be any suitable separator commonly used in lithium batteries. The separator can have, for example, low resistance to ion migration in the electrolyte and electrolyte retention capabilities. The separator can be, for example, glass fiber, polyester, Teflon, PE, PP, PTFE, and combinations thereof, each of which can be in nonwoven or woven fabric form. For lithium-ion batteries, rollable separators including, for example, PE or PP can be used. Separators with good organic electrolyte retention capabilities can be used in lithium-ion polymer batteries.

[0176] The diaphragm can be prepared, for example, according to the following example method, but the embodiments are not limited thereto, and the method can be controlled according to the desired conditions.

[0177] First, a membrane composition can be prepared by mixing a polymer resin, filler, and solvent. Then, the membrane composition can be directly coated onto the electrode and dried to form a membrane. In some embodiments, a membrane lamination obtained by casting the membrane composition onto a support, drying it, and separating it from the support can be laminated onto the electrode to form a membrane.

[0178] There are no restrictions on the polymers used in the preparation of the diaphragm; any suitable polymer that can be used as a binder for the electrode plates can be used. For example, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or mixtures thereof can be used.

[0179] Next, the electrolyte can be prepared. The electrolyte is described in the same way as a lithium battery.

[0180] like Figure 6 As shown, the 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 can be wound or folded to form a battery structure. The formed battery structure can be housed in a battery casing 5. The battery casing 5 can then be filled with an organic electrolyte and sealed with a cover assembly 6, thereby completing the manufacture of the lithium battery 1. The battery casing 5 can be cylindrical, but its shape is not limited to this. For example, the battery casing 5 can be square, thin-film, etc.

[0181] like Figure 7As shown, the lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 can be disposed between the positive electrode 3 and the negative electrode 2, and the positive electrode 3, the negative electrode 2, and the separator 4 can be wound or folded to form a battery structure 7. The formed battery structure 7 can be housed in a battery casing 5. The lithium battery 1 may include electrode terminals 8 serving as electrical paths for guiding the current formed in the battery structure 7 to the outside. The battery casing 5 can then be filled with an organic electrolyte and sealed to complete the manufacture of the lithium battery 1. The battery casing 5 can be square, but its shape is not limited to this. For example, the battery casing 5 can be cylindrical, thin-film, etc.

[0182] like Figure 8 As shown, the lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 can be disposed between the positive electrode 3 and the negative electrode 2 to form a battery structure 7. The battery structure 7 can be laminated in a dual-cell structure and then housed in a battery casing 5. The lithium battery 1 may include electrode terminals 8 serving as electrical paths for guiding the current formed in the battery structure 7 to the outside. The battery casing 5 can then be filled with an organic electrolyte and sealed to complete the manufacture of the lithium battery 1. The battery casing 5 can be square, but its shape is not limited to this. For example, the battery casing 5 can be cylindrical, thin-film, etc.

[0183] Pouch-type lithium batteries correspond to the use of pouches as a type of battery for use with lithium batteries. Figure 7 and Figure 8 The battery casing of a lithium battery. A pouch-type lithium battery may include at least one battery assembly. A separator may be disposed between the positive electrode and the negative electrode to form a battery structure. The battery assembly may be laminated into a dual-cell structure, impregnated with an organic electrolyte, and housed and sealed in a pouch to complete the manufacture of the pouch-type lithium battery. For example, although not shown in the figures, the aforementioned positive electrode, negative electrode, and separator may simply be stacked and housed in a pouch as an electrode assembly, or may be wound or folded into an electrode assembly in the form of an electrode core and then housed in a pouch. An organic electrolyte may then be injected into the pouch and sealed to complete the manufacture of the lithium battery.

[0184] Because of their excellent lifespan and high-rate characteristics, lithium batteries can be used in applications such as electric vehicles (EVs). For example, lithium metal batteries can be used in hybrid vehicles (such as plug-in hybrid electric vehicles (PHEVs)). Lithium metal batteries are also suitable for applications requiring high energy storage, such as electric bicycles and power tools.

[0185] Multiple lithium batteries can be stacked to form a battery module, and multiple battery modules can form a battery pack. The battery pack can be used in devices that require high capacity and large output. For example, the battery pack can be used in laptop computers, smartphones, electric vehicles, etc. The battery module can include, for example, multiple batteries and a frame for holding the multiple batteries. The battery pack can include, for example, multiple battery modules and bus bars for connecting the battery modules together. The battery module and / or the battery pack can also include a cooling device. Multiple battery packs can be managed by a battery management system. The battery management system can include a battery pack and an electronic control device connected to the battery pack.

[0186] [Composite positive electrode active material: manufacturing method] A method for manufacturing a composite positive electrode active material according to another embodiment includes: providing a first core and a second core; providing a composite; and mechanically grinding the first core, the second core, and the composite to form the composite positive electrode active material, wherein the composite includes: at least one type of first metal oxide; and a first carbonaceous material, at least one type of first metal oxide being disposed in a matrix of the first carbonaceous material matrix, the first metal oxide being represented by the formula M a O b (where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3, b is not an integer), and M is at least one metal selected from Groups 2 to 13, 15, and 16 of the periodic table.

[0187] For use as the first core, for example, the aforementioned first lithium transition metal oxide can be provided. The first lithium transition metal oxide can be, for example, a first lithium transition metal oxide having a layered structure and a Ni content of 60 mol% or more. The first lithium transition metal oxide can be, for example, a compound represented by one of Formulas 1 to 6.

[0188] For use as the second core, for example, the aforementioned second lithium transition metal oxide can be provided. The second lithium transition metal oxide can have, for example, an olivine-type crystal structure. The second lithium transition metal oxide can be, for example, a compound represented by one of Formulas 7 and 8.

[0189] A composite can be provided. Providing the composite can include, for example, supplying a reaction gas composed of a carbon source gas to a structure including a metal oxide, and then performing a heat treatment to provide the composite. Providing the composite can include, for example, supplying a reaction gas formed from a carbon source gas to at least one of second metal oxides represented by M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3, c can be an integer), and performing a heat treatment to prepare the composite, where M can be at least one metal selected from Groups 2 to 13, 15, and 16 of the periodic table.

[0190] The carbon source gas can be a gas composed of a compound represented by Formula 10, or can be a mixed gas including at least one selected from the group consisting of a compound represented by Formula 10, a compound represented by Formula 11, and an oxygen-containing gas represented by Formula 12.

[0191] Formula 10 C n H (2n+2-a) [OH] a Wherein, in Formula 10, n can be 1 to 20, and a can be 0 or 1; Formula 11 C n H 2n Wherein, in Formula 11, n can be 2 to 6; Formula 12 C x H y O z Wherein, in Formula 12, x can be 0 or an integer from 1 to 20, y can be 0 or an integer from 1 to 20, and z is 1 or 2.

[0192] The compound represented by Formula 10 and the compound represented by Formula 11 can be at least one selected from the group consisting of methane, ethylene, propylene, methanol, ethanol, and propanol. The oxygen-containing gas represented by Formula 12 can include, for example, carbon dioxide (CO2), carbon monoxide (CO), water vapor (H2O), or a mixture thereof.

[0193] In providing a reaction gas composed of a carbon source gas to a second metal oxide represented by M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3, c is an integer) and heat-treating the second metal oxide, a cooling process can be further performed by using at least one inert gas selected from the group consisting of nitrogen, helium, and argon. The cooling process refers to adjusting the reaction temperature to room temperature (20 °C to 25 °C). The cooling gas can include at least one inert gas selected from the group consisting of nitrogen, helium, and argon.

[0194] In the method for preparing the composite, the process of growing carbonaceous materials (for example, graphene) can be carried out under various conditions according to gas reactions.

[0195] According to the first condition, for example, it is possible to first introduce into it a second metal oxide represented by M a O cA reactor for a second metal oxide represented by (where 0 < a ≤ 3 and 0 < c ≤ 4, and when a is 1, 2, or 3, c is an integer) supplies methane and can raise the reaction temperature to a heat treatment temperature (T). The time for raising the temperature to the heat treatment temperature (T) can be from 10 minutes to about 4 hours, and the heat treatment temperature (T) can be in the range of about 700 °C to about 1,100 °C. The heat treatment can be carried out at the heat treatment temperature (T) during the reaction time. The reaction time can be, for example, 4 hours to 8 hours. The product of the heat treatment can be cooled to room temperature to prepare the composite. The time required for the process of cooling from the heat treatment temperature (T) to room temperature can be, for example, about 1 hour to about 5 hours.

[0196] According to the second condition, for example, hydrogen can first be supplied to a reactor in which a second metal oxide represented by M a O c (where 0 < a ≤ 3 and 0 < c ≤ 4, and when a is 1, 2, or 3, c is an integer), and the reaction temperature can be raised to the heat treatment temperature (T). The time for raising the temperature to the heat treatment temperature (T) can be from 10 minutes to about 4 hours, and the heat treatment temperature (T) can be in the range of about 700 °C to about 1,100 °C. After heat treatment for a predetermined reaction time at the heat treatment temperature (T), methane gas can be supplied, and heat treatment can be carried out for the remaining reaction time. The reaction time can be, for example, 4 hours to 8 hours. The product of the heat treatment can be cooled to room temperature to prepare the composite. In the cooling process, nitrogen can be supplied to the product of the heat treatment. The time required for the process of cooling from the heat treatment temperature (T) to room temperature can be, for example, about 1 hour to about 5 hours.

[0197] According to the third condition, for example, hydrogen can first be supplied to a reactor in which a second metal oxide represented by M a O c (where 0 < a ≤ 3 and 0 < c ≤ 4, and when a is 1, 2, or 3, c is an integer), and the reaction temperature can be raised to the heat treatment temperature (T). The time for raising the temperature to the heat treatment temperature (T) can be from 10 minutes to about 4 hours, and the heat treatment temperature (T) can be in the range of about 700 °C to about 1,100 °C. After heat treatment for a predetermined reaction time at the heat treatment temperature (T), a mixed gas of methane and hydrogen can be supplied, and heat treatment can be carried out for the remaining reaction time. The reaction time can be, for example, 4 hours to 8 hours. The product of the heat treatment can be cooled to room temperature to prepare the composite. In the cooling process, nitrogen can be supplied to the product of the heat treatment. The time required for the process of cooling from the heat treatment temperature (T) to room temperature can be, for example, about 1 hour to about 5 hours.

[0198] In the preparation of the composite, a composite with excellent electrical conductivity can be obtained when the carbon source gas includes water vapor. There is no limitation on the water vapor content in the mixed gas; based on 100 vol% of the total carbon source gas, the water vapor content in the mixed gas can be, for example, in the range of about 0.01 vol% to about 10 vol%. The carbon source gas can be, for example: methane; a mixed gas including methane and an inert gas; or a mixed gas including methane and an oxygen-containing gas.

[0199] The carbon source gas can be, for example, methane; a mixture of methane and carbon dioxide; or a mixture of methane, carbon dioxide, and water vapor. The molar ratio of methane to carbon dioxide in the methane and carbon dioxide mixture can be in the range of about 1:0.20 to about 1:0.50, about 1:0.25 to about 1:0.45, or about 1:0.30 to about 1:0.40. The molar ratio of methane to carbon dioxide to water vapor in the methane, carbon dioxide, and water vapor mixture can be in the range of about 1:0.20 to about 0.50:0.01 to 1.45, about 1:0.25 to about 0.45:0.10 to 1.35, or about 1:0.30 to about 0.40:0.50 to 1.0.

[0200] The carbon source gas can be, for example, carbon monoxide or carbon dioxide. The carbon source gas can be, for example, a mixture of methane and nitrogen. The molar ratio of methane to nitrogen in the methane and nitrogen mixture can be in the range of about 1:0.20 to about 1:0.50, about 1:0.25 to about 1:0.45, or about 1:0.30 to about 1:0.40. The carbon source gas may not include inert gases such as nitrogen.

[0201] The heat treatment pressure can be selected by considering the heat treatment temperature, the composition of the gas mixture, and the desired carbon coating content. The heat treatment pressure can be controlled by adjusting the content of the inflow and outflow gas mixtures. The heat treatment pressure can be, for example, greater than or equal to about 0.5 atm, greater than or equal to about 1 atm, greater than or equal to about 2 atm, greater than or equal to about 3 atm, greater than or equal to about 4 atm, or greater than or equal to about 5 atm. The heat treatment pressure can be, for example, in the range of about 0.5 atm to about 10 atm, about 1 atm to about 10 atm, about 2 atm to about 10 atm, about 3 atm to about 10 atm, about 4 atm to about 10 atm, or about 5 atm to about 10 atm.

[0202] The time for heat treatment is not particularly limited and can be selected considering the heat treatment temperature, heat treatment pressure, composition of the gas mixture, and desired carbon coating content. For example, the reaction time at the heat treatment temperature can be, for example, in the range of 10 minutes to 100 hours, 30 minutes to 90 hours, or 50 minutes to 40 hours. For example, as the time for heat treatment increases, the content of deposited carbon (e.g., graphene) increases, and thus the electrical properties of the composite can be improved. However, this trend may not necessarily be proportional to the time. For example, after a predetermined period of time, deposition of carbon (e.g., graphene) may no longer occur, or the deposition rate of graphene may decrease.

[0203] Through the gas-phase reaction of the carbon source gas, even at a relatively low temperature, a composite can be obtained by providing a uniform coating of a carbonaceous material (e.g., graphene) on one or more of the second metal oxides represented by M a O c (0 < a ≤ 3, and 0 < c ≤ 4, where if a is 1, 2, or 3, c can be an integer) and their reduction products (e.g., the first metal oxides represented by M a O b (0 < a ≤ 3, and 0 < b < 4, and when a is 1, 2, or 3, b may not be an integer)).

[0204] The composite can, for example, include: a matrix of a carbonaceous material (e.g., a graphene matrix) having at least one structure selected from a spherical structure, a helical structure having a plurality of spherical structures connected to each other, a cluster structure having a plurality of aggregated spherical structures, and a sponge structure; and at least one selected from the first metal oxides represented by M a O b (0 < a ≤ 3, 0 < b < 4, where a is 1, 2, or 3, and b is not an integer) and the second metal oxides represented by M a O c (0 < a ≤ 3, 0 < c ≤ 4, if a is 1, 2, or 3, c can be an integer), disposed within the graphene matrix.

[0205] Next, the first lithium transition metal oxide, the second lithium transition metal oxide, and the composite can be mechanically ground to prepare a composite positive electrode active material. For the grinding, a Nobilta mixer or the like can be used. The rotation speed of the mixer during grinding can be, for example, 1,000 rpm to 5,000 rpm. The grinding time can be, for example, 5 minutes to 100 minutes. The average particle diameter D50 of the composite for the mechanical grinding of the first lithium transition metal oxide, the second lithium transition metal oxide, and the above composite can be, for example, 50 nm to 200 nm, 100 nm to 300 nm, or 200 nm to 500 nm. In the mechanical grinding process, the grinding method is not particularly limited, and any method capable of bringing the first lithium transition metal oxide, the second lithium transition metal oxide, and the composite into contact in the art can be used.

[0206] The present disclosure will be described in more detail by the following examples and comparative examples. However, the following examples are for illustrative purposes only and should not be construed as limiting the scope of the disclosure.

[0207] (Preparation of composite) Preparation Example : Al2O3@Gr composite Al2O3 particles (average particle diameter: about 15 nanometers (nm)) were placed in a reactor, and then the temperature inside the reactor was raised to 1,000 °C under the condition of supplying CH4 to the reactor at about 300 standard cubic centimeters per minute (sccm) for about 30 minutes at 1 atmosphere (atm).

[0208] Subsequently, heat treatment was performed while maintaining the same temperature for 7 hours. Then, the temperature inside the reactor was adjusted to room temperature (20 °C to 25 °C) to obtain a composite in which Al2O3 particles and their reduced product Al2O z (where 0 < z < 3) particles are embedded in graphene.

[0209] Here, the content of alumina included in the composite is 60 wt%.

[0210] (Preparation of composite positive electrode active material) Preparation Example 1 : Prepare NCA91 coated with 0.36 wt% of Al2O3@Gr composite (aluminum oxide: 0.36 wt%) and LFP coated with 0.36 wt% of Al2O3@Gr composite (aluminum oxide: 0.36 wt%) (weight ratio 90:10) Lithium nickel with an average particle diameter D50 of 14 μm 0.91 Cobalt 0.05 Aluminum 0.04O2 (hereinafter referred to as NCA91), LiFePO4 with an average particle size D50 of 3.5 μm (hereinafter referred to as LFP), and the composite prepared in the preparation example were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight ratio of the composite in the preparation example was 99.64:0.36. Furthermore, the weight ratio of NCA91 to LFP was 90:10.

[0211] Preparation Example 2 NCA91 coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) and LFP coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) (weight ratio 80:20) LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91), LiFePO4 with an average particle size D50 of 3.5 μm (hereinafter referred to as LFP), and the composite prepared in the preparation example were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight ratio of the composite in the preparation example was 99.64:0.36. Furthermore, the weight ratio of NCA91 to LFP was 80:20.

[0212] Preparation Example 3 NCA91 coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) and LFP coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) (weight ratio 75:25) LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91), LiFePO4 with an average particle size D50 of 3.5 μm (hereinafter referred to as LFP), and the composite prepared in the preparation example were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight ratio of the composite in the preparation example was 99.64:0.36. Furthermore, the weight ratio of NCA91 to LFP was 75:25.

[0213] Preparation Example 4 NCA91 coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) and LFP coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) (weight ratio 50:50) LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91), LiFePO4 with an average particle size D50 of 3.5 μm (hereinafter referred to as LFP), and the composite prepared in the preparation example were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight of the composite in the preparation example was 99.64:0.36. Furthermore, the weight ratio of NCA91 to LFP was 50:50.

[0214] Preparation Example 5 NCA91 coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) and LFP coated with 0.36 wt% Al2O3@Gr composite (alumina: 0.36 wt%) (weight ratio 20:80) LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91), LiFePO4 (hereinafter referred to as LFP) with an average particle size D50 of 3.5 μm, and the composite prepared in the preparation example were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight ratio of the composite in the preparation example was 99.64:0.36. Furthermore, the weight ratio of NCA91 to LFP was 20:80.

[0215] Preparation Example 6 NCA91 (alumina: 0.36 wt%) coated with 0.36 wt% Al2O3@Gr composite and LFP LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04O2 (hereinafter referred to as NCA91) and the composite prepared in the above preparation example were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain 0.36 wt% Al2O3@Gr composite coated NCA91 (alumina: 0.36 wt%). Subsequently, LiFePO4 (hereinafter referred to as LFP) with an average particle size D50 of 3.5 μm was added to the 0.36 wt% Al2O3@Gr composite coated NCA91 (alumina: 0.36 wt%), and then milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain the composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight of the composite in the preparation example was 99.64:0.36. In addition, the weight ratio of NCA91 to LFP is 90:10.

[0216] Comparative preparation example 1 NCA91 and LFP LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) and LiFePO4 (hereinafter referred to as LFP) with an average particle size D50 of 3.5 μm were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The weight ratio of NCA91 to LFP was 90:10.

[0217] Comparative preparation example 2 NCA91 Prepare LiNi with an average particle size D50 of 14 μm without grinding. 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91).

[0218] Comparative preparation example 3 Preparation of carbon-coated NCA91 and carbon-coated LFP 0.36 wt% carbon black was added to a Thinky mixer and coated onto NCA91 (average particle size D50 of 14 μm) and LPF (average particle size D50 of 3.5 μm) for approximately 2 to 5 minutes each at a speed of 1000 to 2000 rpm to prepare carbon-coated NCA91 and carbon-coated LFP. The total weight ratio of NCA91 and LFP to carbon was 99.64:0.36. Additionally, the weight ratio of NCA91 to LFP was 90:10.

[0219] Comparative preparation example 4 Preparation of Gr-coated NCA91 and Gr-coated LFP (weight ratio 90:10) LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91), LiFePO4 (hereinafter referred to as LFP) with an average particle size D50 of 3.5 μm, and graphene were milled using a Nobilta mixer (Hosokawa, Japan) at a speed of approximately 1000 rpm to 2000 rpm for approximately 5 to 30 minutes to obtain a composite positive electrode active material. The total weight ratio of NCA91 and LFP to the weight of graphene was 99.64:0.36. Furthermore, the weight ratio of NCA91 to LFP was 90:10.

[0220] (Manufacturing of lithium batteries (half-cells)) Example 1 (Preparation of dry positive electrode film and dry positive electrode) The dry composite positive electrode active material, dry carbon conductive material, and polytetrafluoroethylene (PTFE) as a dry binder prepared in Example 1 were added to a blade mixer in a weight ratio of 96:2:2, and the mixture was initially dry-mixed at 1200 rpm for 10 minutes at 25°C to prepare a first dry mixture in which the dry positive electrode active material, dry conductive material, and dry binder were uniformly mixed. For the dry carbon conductive material, a mixture in which carbon nanotubes (CNTs) and Ketjen Black (ECP) were mixed in a ratio of 7:3 was used.

[0221] Subsequently, in order to allow the fiberization of the binder to proceed, the first dry mixture was subjected to a second dry mixing process for 25 minutes at 25°C and 4,000 rpm to prepare a second dry mixture.

[0222] No separate solvent is used in the preparation of the first dry mixture and the second dry mixture.

[0223] The prepared second dry mixture was added to an extruder to extrude a sheet-type self-standing dry positive electrode film. Here, the extrusion pressure was 60 MPa.

[0224] The prepared self-standing dry positive electrode film was rolled to prepare a rolled self-standing dry positive electrode film. Here, the rolling pressure was 3.5 tons / cm². 2 The thickness of the dry positive electrode film is approximately 200 μm.

[0225] Then, prepare the positive electrode current collector, in which the carbon layer is coated onto one side of a 25μm thick aluminum film.

[0226] To prepare the carbon layer, a carbon conductive material (e.g., Danka black) and polyvinylidene fluoride (PVDF) are coated onto an aluminum film and then dried. Here, the thickness of the carbon layer disposed on one side of the positive electrode current collector is approximately 1 μm.

[0227] Then, the rolled dry positive electrode film is arranged on one side of the positive electrode current collector to prepare the dry positive electrode.

[0228] (Preparation of coin batteries) A coin battery was manufactured by using a prepared positive electrode, lithium metal as a counter electrode, a PTFE membrane, and a solution of 1.3 M LiPF6 dissolved in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + dimethyl carbonate (DMC) (volume ratio 3:4:3).

[0229] Example 2 Except that the composite positive electrode active material of Preparation Example 2 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, the dry positive electrode, and the coin battery are manufactured in the same manner as in Example 1.

[0230] Example 3 Except that the composite positive electrode active material of Preparation Example 3 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, the dry positive electrode, and the coin battery are manufactured in the same manner as in Example 1.

[0231] Example 4 Except that the composite positive electrode active material of Preparation Example 4 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, dry positive electrode and coin battery are manufactured in the same manner as in Example 1.

[0232] Example 5 Except that the composite positive electrode active material of Preparation Example 5 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, dry positive electrode and coin battery are manufactured in the same manner as in Example 1.

[0233] Example 6 Except that the composite positive electrode active material of Preparation Example 6 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, the dry positive electrode, and the coin battery are manufactured in the same manner as in Example 1.

[0234] Comparison Example 1 Except that the composite positive electrode active material of Comparative Preparation Example 1 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, dry positive electrode and coin battery are manufactured in the same manner as in Example 1.

[0235] Comparison Example 2 Except that NCA91 from Comparative Preparation Example 2 was used instead of the composite positive electrode active material from Preparation Example 1, the dry electrode film, dry positive electrode, and coin cell were manufactured in the same manner as in Example 1.

[0236] Compare Example 3 Except that the composite positive electrode active material of Comparative Preparation Example 3 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, dry positive electrode and coin battery are manufactured in the same manner as in Example 1.

[0237] Compare Example 4 Except that the composite positive electrode active material of Comparative Preparation Example 4 is used instead of the composite positive electrode active material of Preparation Example 1, the dry electrode film, dry positive electrode and coin battery are manufactured in the same manner as in Example 1.

[0238] Evaluation Example 1: SEM, HR-TEM, and SEM-EDS Analysis The composite positive electrode active material prepared in Example 1 was analyzed by scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy (EDS).

[0239] For SEM-EDX analysis, the FEI Titan 80-300, available from Philips, was used. Figure 3 This is a SEM image of the composite positive electrode active material prepared in Preparation Example 1.

[0240] Reference Figure 3 It was confirmed that in the composite positive electrode active material prepared in Preparation Example 1, the graphene-containing composite was arranged on the large-diameter NCA91 core and the small-diameter LFP core.

[0241] Evaluation Example 2: Evaluation of Specific Capacity and Mixture Density For the composite positive electrode active materials prepared in Preparation Examples 1 to 5, the specific capacity and the density of the mixture were measured.

[0242] The specific capacity of the composite positive electrode active material was measured by discharging each of the coin cells comprising the composite positive electrode active materials prepared in Preparation Examples 1 to 5 for 5 hours in the range of 3.0V to 4.3V to obtain a charge (current × hour, milliampere-hours (mAh)) and dividing the charge by the weight of the positive electrode active material. The density of the mixture was calculated by measuring the weight and volume (area × thickness) of the positive electrode.

[0243] The specific capacity and mixture density of the composite positive electrode active materials prepared in Preparation Examples 1 to 5 are shown in Table 1.

[0244] Table 1

[0245] As shown in Table 1, it was confirmed that the specific capacity and mixture density increased with the increase of the content of NCA coated with Al2O3@Gr composite in the composite positive electrode active material.

[0246] Evaluation Example 3: Evaluation of charge-discharge characteristics at high temperature (40℃) Each of the lithium-ion batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 4 was charged at 25°C with a constant current at a rate of 0.1C until the voltage reached 4.3V (vs. Li), and then cut off with a current at a rate of 0.05C while maintaining the voltage at 4.3V in constant voltage mode. Subsequently, each of the lithium-ion batteries was discharged at a constant current at a rate of 0.1C until the voltage reached 2.8V (vs. Li) (formation cycling).

[0247] Each lithium-ion battery that has undergone formation cycling is charged at 25°C with a constant current at a rate of 0.5C until the voltage reaches 4.3V (vs. Li), then cut off with a current at a rate of 0.05C while maintaining the voltage at 4.3V in constant voltage mode. Subsequently, each lithium-ion battery is discharged at a constant current at a rate of 0.5C until the voltage reaches 2.8V (vs. Li) (cycle 1). This cycle is repeated under the same conditions until cycle 50.

[0248] A 10-minute stop time was provided after each charge and discharge cycle in all charge and discharge cycles. The results of measuring the charge capacity, discharge capacity, efficiency, electrode density, and capacity retention [%] in the first cycle of the high-temperature charge and discharge experiments are shown in Table 2.

[0249] In addition, in the high-temperature charge and discharge experiments, the results of measuring the capacity retention rate [%] in each cycle from the 1st cycle to the 50th cycle are shown below. Figure 5 In the middle. The capacity retention rate is defined by Equation 1.

[0250] Equation 1 Capacity retention per cycle [%] = (Discharge capacity per cycle / Discharge capacity of the first cycle) × 100 Evaluation Example 4: Measurement of Gas Generation The content of gas produced when the lithium batteries manufactured in Examples 1 to 6 and Comparative Examples 1 to 4 are placed at 130°C for 1 hour.

[0251] Specifically, the charged positive electrode is placed in a bag, sealed, and weighed. After 1 hour at 130°C, the weight change (including the gas generated from the positive electrode) obtained by measuring the density of the bag is converted into volume, and the amount of gas generated is calculated according to Archimedes' principle.

[0252] The measurement results are shown in Table 2.

[0253] Table 2

[0254] As shown in Table 2, compared with the lithium batteries of Comparative Examples 1 to 4, the lithium batteries of Examples 1 to 6 have improved life characteristics at high temperatures.

[0255] Compared to the lithium battery in Example 6, the lithium batteries in Examples 1 to 5 produce relatively less gas.

[0256] Compared with the lithium batteries of Examples 4 and 5, the lithium batteries of Examples 1 to 3 have relatively superior initial capacity and electrode density.

[0257] <Description of reference numerals in the attached figures> 1. Lithium battery; 2. Negative electrode 3. Positive electrode; 4. Diaphragm 5. Battery casing; 6. Cover assembly 7. Battery structure; 8. Electrode terminals 10 first cores; 20 second cores 30 shell; 31 first metal oxide 32. First-class carbon materials; 33. Second-class carbon materials 100 composite positive electrode active material.

Claims

1. A composite positive electrode active material, the composite positive electrode active material comprising: A first core, comprising a first lithium transition metal oxide; A second core, comprising a second lithium transition metal oxide; And A shell, disposed on the surface of at least one of the first core and the second core, The shell comprising: at least one type of first metal oxide; and a first carbonaceous material, Wherein the at least one type of first metal oxide is disposed in the matrix of the first carbonaceous material, The at least one type of first metal oxide is represented by the formula M a O b where 0 < a ≤ 3, 0 < b < 4, when a is 1, 2 or 3, b is not an integer, and M is at least one metal in Groups 2 to 13, 15 and 16 of the Periodic Table The first core and the second core have different particle sizes, The first lithium transition metal oxide has a layered crystal structure and a nickel content of 60 mol% or more, and The second lithium transition metal oxide has an olivine-type crystal structure.

2. The composite positive electrode active material according to claim 1, wherein, The particle size of the first lithium transition metal oxide included in the first core is greater than the particle size of the second lithium transition metal oxide included in the second core.

3. The composite positive electrode active material according to claim 1, wherein, The particle size distributions of the first lithium transition metal oxide and the second lithium transition metal oxide are bimodal particle size distributions, and The particle size ratio of the first lithium transition metal oxide to the second lithium transition metal oxide is 3:1 to 40:

1.

4. The composite positive electrode active material according to claim 1, wherein, The particle size of the first lithium transition metal oxide is greater than 10 μm and less than or equal to 30 μm, and The particle size of the second lithium transition metal oxide is 1 μm to 10 μm.

5. The composite positive electrode active material according to claim 1, wherein, The weight ratio of the first lithium transition metal oxide to the second lithium transition metal oxide is 90:10 to 60:

40.

6. The composite positive electrode active material according to claim 1, wherein, The first lithium transition metal oxide is represented by a formula selected from Formula 1 to Formula 6: <Formula 1> Li a Ni x Co y M z O 2-b A b Wherein, in 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 manganese (Mn), cobalt (Co), 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, <Formula 2> LiNi x Co y Mr z O2 <Formula 3> LiNi x Co y Al z O2 Wherein, in Formula 2 and Formula 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1, <Formula 4> LiNi x Co y Mr z Al w O2 Wherein, in 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, <Formula 5> Li a Co x M y O 2-b A b Wherein, in 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), cobalt (Co), 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, <Formula 6> Li a Ni x Mr y M' z O 2-b A b wherein, in Formula 6, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0 < x ≤ 0.3, 0.5 ≤ y < 1, 0 < z ≤ 0.3, and x + y + z = 1, M' is cobalt (Co), 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.

7. The composite positive electrode active material according to claim 1, wherein the second lithium transition metal oxide is represented by a formula selected from Formula 7 and Formula 8: <Formula 7> Yes a M1 x M2 y PO 4-b X b wherein, in Formula 7, 0.90 ≤ a ≤ 1.1, 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0.9 < x + y < 1.1, and 0 ≤ b ≤ 2, M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof, and M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y) or a combination thereof, and X is O, F, S, P or a combination thereof, <Formula 8> Li a M3 z PO4 wherein, in Formula 8, 0.90 ≤ a ≤ 1.1, 0.9 ≤ z ≤ 1.1, and M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof.

8. The composite positive electrode active material according to claim 1, wherein, The shell is disposed on the surfaces of the first core and the second core.

9. The composite positive electrode active material according to claim 1, wherein the metal included in the at least one type of first metal oxide is at least one metal selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb and Se, and The at least one type of first metal oxide is at least one selected from the following: 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 [[ID=十六]]], 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 SeO y where 0 < y < 2.

10. The composite positive electrode active material according to claim 1, wherein the shell further includes a second metal oxide, The second metal oxide is represented by the formula M a O c where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3, c is an integer ​ ​ ​ 11. The composite positive electrode active material according to claim 10, wherein, The second metal oxide is selected from Al2O3, NbO, NbO2, Nb2O5, MgO, Sc2O3, TiO2, ZrO2, V2O3, WO2, MnO2, Fe2O3, Co3O4, PdO, CuO, AgO, ZnO, Sb2O3, and SeO2, and The first metal oxide of at least one type is a reduction product of the second metal oxide.

12. The composite positive electrode active material according to claim 1, wherein, The shell has a thickness of 0.1 nm to 5 μm and has a single-layer or multi-layer structure.

13. The composite positive electrode active material according to claim 1, wherein, Based on the total weight of the composite positive electrode active material, the weight of the shell is from 0.01 wt% to 5 wt%.

14. The composite positive electrode active material according to claim 1, wherein the composite positive electrode active material further comprises a third metal doped on the first core or the second core, or a third metal oxide coated on the first core or the second core. The shell is disposed on the third metal oxide, and The third metal oxide is an oxide of at least one third metal selected from aluminum (Al), zirconium (Zr), tungsten (W), and cobalt (Co).

15. The composite positive electrode active material according to claim 1, wherein, The shell also includes a second carbon-based material. The second carbon-based material is a fibrous carbon-based material with an aspect ratio of 10 or greater. The second type of carbon material includes carbon nanofibers, carbon nanotubes, or combinations thereof. The carbon nanotubes include primary carbon nanotube structures, secondary carbon nanotube structures formed by the aggregation of multiple particles of the primary carbon nanotube structures, or combinations thereof. The primary carbon nanotube structure is a single carbon nanotube unit.

16. The composite positive electrode active material according to claim 1, wherein, The first carbon-based material is chemically bonded to the transition metal of the first lithium transition metal oxide or the transition metal of the second lithium transition metal oxide. The carbon atoms (C) of the first carbon-based material are bonded to the transition metal (Me) of the first lithium transition metal oxide or the transition metal (Me) of the second lithium transition metal oxide through oxygen-mediated CO-Me bonds, or The first metal oxide of at least one type is bonded to the first carbon-based material by chemical bonds.

17. A positive electrode, the positive electrode comprising: Positive electrode current collector; as well as A positive electrode active material layer is disposed on one or both sides of the positive electrode current collector, and includes the composite positive electrode active material according to any one of claims 1 to 16.

18. The positive electrode according to claim 17, wherein, The positive electrode current collector includes a substrate film and a metal layer disposed on one or both sides of the substrate film. The substrate film comprises a polymer, including polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or combinations thereof, and The metal layer includes indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof.

19. The positive electrode according to claim 17, wherein, The positive electrode is either a dry positive electrode or a wet positive electrode.

20. A lithium battery, the lithium battery comprising: The positive electrode according to claim 17; negative electrode; as well as An electrolyte is disposed between the positive electrode and the negative electrode.

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