Positive electrode active material and preparation method therefor

Abstract

A positive electrode active material, according to one embodiment of the present invention, is a positive electrode active material comprising a high-Ni metal oxide and may comprise: a first metal element having an oxidation number of +6; a second metal element having an oxidation number of +5; a third metal element having an oxidation number of +4; and a fourth metal element having an oxidation number of +2 or +3.

Description

Positive electrode active material and method for producing the same

[0001] [Cross-reference with related applications]

[0002] This application claims the benefit of priority to Korean Patent Application No. 2023-0150223, filed November 2, 2023, the entire contents of which are incorporated herein by reference.

[0003]

[0004] [Technical Field]

[0005] The present invention relates to a positive electrode active material and a method for producing the same.

[0006] Lithium secondary batteries, which allow for repeated charging and discharging, are attracting attention as an alternative to fossil fuels. Lithium secondary batteries have been primarily used in traditional handheld devices such as cell phones, video cameras, and power tools. However, their applications are gradually expanding to include electric vehicles (EVs, HEVs, PHEVs), large-capacity energy storage systems (ESSs), and uninterruptible power supply systems (UPSs). A lithium secondary battery consists of an electrode assembly, which is a collection of unit cells each having a structure in which a positive and negative electrode plates, each coated with an active material on a current collector, are arranged with a separator between them, and an outer case, i.e., a battery case, that seals and encloses the electrode assembly together with an electrolyte.

[0007] Lithium composite transition metal oxides are used as positive electrode active materials for lithium secondary batteries, and among these, lithium cobalt oxide of LiCoO2, lithium manganese oxide (such as LiMnO2 or LiMn2O4), lithium iron phosphate compound (LiFePO4), or LiNiO2 are mainly used. In addition, as a method to improve the low thermal stability of LiNiO2 while maintaining the excellent reversible capacity, nickel manganese lithium composite metal oxides in which some of the nickel is replaced with manganese, which has excellent thermal stability, and NCM in which manganese and cobalt are replaced are being used.

[0008] Nickel-rich transition metal oxides (high-Ni NCMs) are layered transition metal oxides with a nickel content of 80% or more. Nickel, cobalt, and manganese are the most commonly used transition metals as battery cathode materials. Among these, nickel is the only one that can change its valence from +2 to +4. Therefore, when the nickel content in high-Ni NCM increases, the number of lithium ions that can enter the lithium layer can double compared to when other transition metals are used, resulting in increased capacity. When the nickel content is 80% or higher, Ni-rich oxides exhibit a high capacity of 200 mAh / g, the second highest capacity after lithium-rich oxides.

[0009] High-Ni NCM not only has high capacity, but also does not require increased operating voltage like lithium-rich oxide to achieve high capacity. It also exhibits a relatively high electrical conductivity of 10-5 S / cm, which, while lower than LCO, is still quite high, preventing significant capacity loss even at high C rates. Because nickel, which is relatively inexpensive compared to cobalt, accounts for most of the material, production costs are very low and it is also environmentally friendly.

[0010] However, the stability degradation and rapid performance degradation due to residual lithium must be addressed. In addition, the rapid cycle performance decline is caused by unwanted tetravalent transition metal ions (especially Ni). 4+ ) is related to the side reaction between Ni and the electrolyte. The highly active Ni 4+ Ions can accelerate electrolyte decomposition, which not only leads to electrolyte depletion and a thick SEI layer, but also to a phase transition from a layered to a rock-salt structure (NiO) on the particle surface. Both phenomena consistently lead to a decrease in lithiation kinetics at the electrode-electrolyte interface.

[0011] Conversely, poor thermal stability leads to oxygen release from the crystal structure when a significant amount of lithium is lost. This oxygen oxidizes the electrolyte, easily generating HF or LiF, which accelerates gas evolution and rapidly reduces the electrochemical properties of the active material. Consequently, this leads to rapid capacity decay. In the case of High-Ni NCM, the inherent structural and electrochemical performance degradation at high temperatures (> 60°C) and high voltages (> 4.5 V) occurs more rapidly than in conventional layered structures, and the amount of gas generated within the battery is also large, making it highly vulnerable to stability.

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] (Patent Document 0001) CN 115548294 A

[0015] The present invention provides a cathode active material having improved stability by doping four or more metal elements into a high-nickel NCM lithium composite metal oxide to lower Gibbs free energy.

[0016] (1) The present invention provides a positive electrode active material comprising a nickel-excess metal oxide, comprising a first metal element having an oxidation state of +6; a second metal element having an oxidation state of +5; a third metal element having an oxidation state of +4; and a fourth metal element having an oxidation state of +2 or +3.

[0017] (2) The present invention provides a positive electrode active material comprising a lithium composite metal oxide represented by the following chemical formula 1.

[0018] [Chemical Formula 1]

[0019] Li a Ni b Co c Mn d M 1 e M 2 f M 3 g M 4h O2

[0020] In the above chemical formula 1,

[0021] Above M 1 is a member selected from the group consisting of metallic elements having an oxidation state of +6,

[0022] Above M 2 is a species selected from the group consisting of metallic elements having an oxidation state of +5,

[0023] Above M 3 is a species selected from the group consisting of metallic elements having an oxidation state of +4,

[0024] Above M 4 is a member selected from the group consisting of metallic elements having an oxidation state of +2 or +3,

[0025] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0026] (3) In the present invention, in the above (2), in the above chemical formula 1, the M 1 Provided is a cathode active material, which is one selected from the group consisting of Cr, Mo, W and Sg.

[0027] (4) The present invention, in any one of the above (2) or (3), in the above chemical formula 1, the M 2 Provided is a cathode active material, which is one selected from the group consisting of Nb, V, Ta, and Db.

[0028] (5) The present invention is one of the above (2) to (4), wherein the above M 3 Provided is a cathode active material, which is one selected from the group consisting of Ti, Zr, Hf, and Rf.

[0029] (6) The present invention is one of the above (2) to (5), wherein the M 4Provided is a cathode active material, which is one selected from the group consisting of Al, Sc, Y, Mg, Ca, and Sr.

[0030] (7) The present invention provides a positive electrode active material that satisfies 0.005≤e≤0.03, 0.005≤f≤0.03, 0.005≤g≤0.03, and 0.005≤h≤0.03 in the chemical formula 1, in any one of (2) to (6).

[0031] (8) The present invention provides a positive electrode active material that satisfies 0.0025≤e≤0.02, 0.0025≤f≤0.02, 0.0025≤g≤0.02, and 0.0025≤h≤0.02 in the chemical formula 1, in any one of (2) to (7).

[0032] (9) The present invention provides a positive electrode active material in any one of the above (2) to (8), wherein the lithium composite metal oxide is represented by the following chemical formula 2.

[0033] [Chemical Formula 2]

[0034] Li a Ni b Co c Mn d Mo e Nb f M 3 g M 4 h O2

[0035] In the above chemical formula 2,

[0036] Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr,

[0037] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0038] (10) The present invention provides a positive electrode active material in any one of the above (2) to (9), wherein the lithium composite metal oxide is represented by the following chemical formula 3.

[0039] [Chemical Formula 3]

[0040] Li a Ni b Co c Mn d Mo e V f M 3 g M 4 h O2

[0041] In the above chemical formula 3,

[0042] Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr,

[0043] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0044] (11) The present invention provides a positive electrode active material in any one of the above (2) to (10), wherein the lithium composite metal oxide is represented by the following chemical formula 4.

[0045] [Chemical Formula 4]

[0046] Li a Ni b Co c Mn d W e Nb f M 3 g M 4 h O2

[0047] In the above chemical formula 4,

[0048] Above M 3 and M 4are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr,

[0049] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0050] (12) The present invention provides a positive electrode active material in any one of the above (2) to (11), wherein the lithium composite metal oxide is represented by the following chemical formula 5.

[0051] [Chemical Formula 5]

[0052] Li a Ni b Co c Mn d W e V f M 3 g M 4 h O2

[0053] In the above chemical formula 5,

[0054] Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr,

[0055] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0056] The cathode active material according to the present invention has improved stability by lowering the Gibbs free energy by mixing four or more metals into a high-nickel NCM lithium composite metal oxide.

[0057] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0058] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0059]

[0060] In the present invention, the content of elements doped in the lithium composite metal oxide can be measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). Specifically, this means that 0.03 g of the cathode active material to be analyzed is dispersed and dissolved in 1 mL of hydrochloric acid, a small amount of hydrogen peroxide and hydrofluoric acid is added, the result is diluted with 50 mL of ultrapure water, and then analyzed using an Avio series (PerkinElmer, Inc) device.

[0061]

[0062] In the present invention, "crystallite" refers to a particle unit having substantially the same crystal orientation, which can be confirmed through EBSD (Electron Backscatter Diffraction) analysis. Specifically, it refers to the smallest particle unit displayed in the same color in an IPF map obtained by EBSD analysis of a cross-section of a positive electrode active material cut through ion milling.

[0063]

[0064] <Cathode active material>

[0065] The present invention provides a positive electrode active material.

[0066] According to one embodiment of the present invention, a cathode active material comprises a nickel-excess metal oxide, wherein the nickel-excess metal oxide comprises: a first metal having an oxidation state of +6; a second metal having an oxidation state of +5; a third metal having an oxidation state of +4; and a fourth metal having an oxidation state of +2 or +3.

[0067] According to one embodiment of the present invention, nickel-rich metal oxide means a layered structure transition metal oxide containing nickel in an amount of 80% or more.

[0068] Conventional nickel-rich metal oxides containing nickel, cobalt, and manganese have a nickel content of 80% or more among the layered transition metal oxides, so they can secure high capacity, but have the problem of reduced structural stability. Specifically, positive electrode active materials containing nickel-rich metal oxides have the disadvantage of undergoing significant changes in lattice constants, i.e., changes in volume within the unit cell, and such changes in volume can cause cracks to occur within the active material particles. These cracks can cause voids to form within the active material, which can lead to a decline in battery performance.

[0069] The inventors of the present invention have found that when nickel-excess metal oxide is doped with four different types of metal elements, including a first metal element having an oxidation state of +6, a second metal element having an oxidation state of +5, a third metal element having an oxidation state of +4, and a fourth metal element having an oxidation state of +2 or +3, the arrangement entropy increases, so that the solubility of the constituent elements increases, and the effective diffusion rate is limited, so that phase separation is suppressed at high temperatures, allowing a higher concentration of solid solution to be synthesized, and thus, regular intermetallic compounds are not formed, and a single phase having a structure much smaller than the number of phases allowed by the Gibbs phase law is formed, thereby lowering the free energy, and improving the mechanical strength and lithium ion diffusion through the lattice strain effect, thereby enhancing the stability, and thus completing the present invention.

[0070]

[0071] A cathode active material according to one embodiment of the present invention includes a lithium composite metal oxide represented by the following chemical formula 1.

[0072] [Chemical Formula 1]

[0073] Li a Ni b Co c Mn d M 1 e M 2 f M 3 g M 4 h O2

[0074] In the above chemical formula 1,

[0075] Above M 1 is a member selected from the group consisting of metallic elements having an oxidation state of +6,

[0076] Above M 2 is a species selected from the group consisting of metallic elements having an oxidation state of +5,

[0077] Above M 3 is a species selected from the group consisting of metallic elements having an oxidation state of +4,

[0078] Above M 4 is a member selected from the group consisting of metallic elements having an oxidation state of +2 or +3,

[0079] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05, b+c+d+e+f+g+h = 1이다.

[0080]

[0081] According to one embodiment of the present invention, the a represents the molar ratio of lithium in the lithium composite metal oxide, and may be 0.8 or more and 1.2 or less, and as a specific example, may be 0.84 or more, 0.88 or more, 0.92 or more, 0.96 or more, or 1.00 or more, and may also be 1.18 or less, 1.16 or less, 1.14 or less, 1.12 or less, 1.10 or less, 1.08 or less, 1.06 or less, or 1.04 or less.

[0082]

[0083] According to one embodiment of the present invention, the b represents the molar ratio of nickel in the lithium composite metal oxide, and may be 0.8 or more and less than 1.0, and as a specific example, may be 0.81 or more, 0.82 or more, 0.83 or more, 0.84 or more, or 0.85 or more, and further, may be 0.98 or less, 0.96 or less, 0.94 or less, 0.92 or less, 0.90 or less, or 0.88 or less.

[0084]

[0085] According to one embodiment of the present invention, c represents the molar ratio of cobalt in the lithium composite metal oxide, and may be greater than 0 and less than or equal to 0.09, and for specific examples, may be greater than or equal to 0.001, greater than or equal to 0.002, greater than or equal to 0.003, greater than or equal to 0.004, or greater than or equal to 0.005, and may also be less than or equal to 0.08, less than or equal to 0.07, less than or equal to 0.06, less than or equal to 0.05, less than or equal to 0.04, or less than or equal to 0.03.

[0086]

[0087] According to one embodiment of the present invention, the d represents the molar ratio of manganese in the lithium composite metal oxide, and may be greater than 0 and less than or equal to 0.09, and for specific examples, may be greater than or equal to 0.001, greater than or equal to 0.002, greater than or equal to 0.003, greater than or equal to 0.004, or greater than or equal to 0.005, and may also be less than or equal to 0.08, less than or equal to 0.07, less than or equal to 0.06, less than or equal to 0.05, less than or equal to 0.04, or less than or equal to 0.03.

[0088]

[0089] According to one embodiment of the present invention, the e is a metal having an oxidation number of +6 in a lithium composite metal oxide. 1 Indicates the molar ratio, and may be greater than 0 and less than or equal to 0.05, and for specific examples, may be 0.001 or more, 0.0015 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, or 0.005 or more, and may also be 0.047 or less, 0.044 or less, 0.041 or less, 0.038 or less, 0.035 or less, or 0.03 or less. When the above-described range is satisfied, the Gibbs energy of the positive electrode active material can be lowered, thereby improving structural stability.

[0090] According to one embodiment of the present invention, the M 1is a metal element with an oxidation number of +6, and may be one selected from the group consisting of Cr, Mo, W, and Sg. Since the metal element with an oxidation number of +6 plays a significant role in reducing Gibbs free energy while minimizing capacity reduction, if the positive electrode active material includes four metal elements, M, which is a metal element with an oxidation number of +6, 1 If it is not included, the Gibbs free energy of the positive electrode active material may not be lowered or the capacity may be reduced.

[0091]

[0092] According to one embodiment of the present invention, the f is M in the lithium composite metal oxide. 2 Indicates the molar ratio, and may be greater than 0 and less than or equal to 0.05, and for specific examples, may be 0.001 or more, 0.0015 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, or 0.005 or more, and may also be 0.047 or less, 0.044 or less, 0.041 or less, 0.038 or less, 0.035 or less, or 0.03 or less. When the above-described range is satisfied, the Gibbs energy of the positive electrode active material can be lowered, thereby improving structural stability.

[0093] According to one embodiment of the present invention, the M 2 is a metallic element with an oxidation number of +5, and may be one selected from the group consisting of Nb, V, Ta, and Db.

[0094]

[0095] According to one embodiment of the present invention, the g is M in a lithium composite metal oxide. 3Indicates the molar ratio, and may be greater than 0 and less than or equal to 0.05, and for specific examples, may be 0.001 or more, 0.0015 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, or 0.005 or more, and may also be 0.047 or less, 0.044 or less, 0.041 or less, 0.038 or less, 0.035 or less, or 0.03 or less. When the above-described range is satisfied, the Gibbs energy of the positive electrode active material can be lowered, thereby improving structural stability.

[0096] According to one embodiment of the present invention, the M 3 is a metallic element with an oxidation number of +4, and may be one selected from the group consisting of Ti, Zr, Hf, and Rf.

[0097]

[0098] According to one embodiment of the present invention, h is M in a lithium composite metal oxide. 4 Indicates the molar ratio, and may be greater than 0 and less than or equal to 0.05, and for specific examples, may be 0.001 or more, 0.0015 or more, 0.0025 or more, 0.003 or more, 0.0035 or more, 0.004 or more, 0.0045 or more, or 0.005 or more, and may also be 0.047 or less, 0.044 or less, 0.041 or less, 0.038 or less, 0.035 or less, or 0.03 or less. When the above-described range is satisfied, the Gibbs energy of the positive electrode active material can be lowered, thereby improving structural stability.

[0099] According to one embodiment of the present invention, the M 4 is a metallic element with an oxidation number of +2 or +3, and may be one selected from the group consisting of Al, Sc, Y, Mg, Ca, and Sr.

[0100]

[0101] The cathode active material according to one embodiment of the present invention may specifically include a lithium metal oxide represented by the following chemical formula 2.

[0102] [Chemical Formula 2]

[0103] Li a Ni b Co c Mn d Mo e Nb f M 3 g M 4 h O2

[0104] In the above chemical formula 2,

[0105] Above M 3 and M 4 Each is a different metallic element, and is one selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr.

[0106] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0107]

[0108] Specifically, the positive electrode active material according to one embodiment of the present invention may include a lithium metal oxide represented by the following chemical formula 3.

[0109] [Chemical Formula 3]

[0110] Li a Ni b Co c Mn d Mo e V f M 3 g M 4 h O2

[0111] In the above chemical formula 3,

[0112] Above M 3 and M 4Each is a different metallic element, and is one selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr.

[0113] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0114]

[0115] Specifically, the positive electrode active material according to one embodiment of the present invention may include a lithium metal oxide represented by the following chemical formula 4.

[0116] [Chemical Formula 4]

[0117] Li a Ni b Co c Mn d W e Nb f M 3 g M 4 h O2

[0118] In the above chemical formula 4,

[0119] Above M 3 and M 4 Each is a different metallic element, and is one selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr.

[0120] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0121]

[0122] The cathode active material according to one embodiment of the present invention may specifically include a lithium metal oxide represented by the following chemical formula 5.

[0123] [Chemical Formula 5]

[0124] Li a Ni b Coc Mn d W e V f M 3 g M 4 h O2

[0125] In the above chemical formula 5,

[0126] Above M 3 and M 4 Each is a different metallic element, and is one selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr.

[0127] 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

[0128]

[0129] Bipolar

[0130] According to one embodiment of the present invention, a positive electrode including the positive electrode active material described above is provided.

[0131] Specifically, the positive electrode includes a positive electrode current collector, and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode active material described above.

[0132] According to one embodiment of the present invention, the positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the current collector to increase the adhesive strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0133] According to one embodiment of the present invention, the positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material described above.

[0134] According to one embodiment of the present invention, at this time, the conductive material is used to provide conductivity to the electrode, and in the battery to be constructed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any particular limitation. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one type alone or a mixture of two or more types thereof may be used. The conductive material may typically be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0135] According to one embodiment of the present invention, the binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the current collector. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The binder may be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0136] According to one embodiment of the present invention, the positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode active material described above is used. Specifically, the positive electrode active material layer forming composition, which is manufactured by mixing or dispersing the positive electrode active material and optionally a binder and a conductive agent in a solvent, is applied onto a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive agent are as described above.

[0137] According to one embodiment of the present invention, the solvent may be a solvent generally used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these may be used alone or as a mixture of two or more. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0138] Additionally, in another method, the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support, and then laminating the resulting film on a positive electrode current collector by peeling it off from the support.

[0139]

[0140] Lithium secondary battery

[0141] According to one embodiment of the present invention, an electrochemical device including the positive electrode is provided. The electrochemical device may be, specifically, a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.

[0142] According to one embodiment of the present invention, the lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode is as described above. In addition, the lithium secondary battery may optionally further include a battery container that houses an electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0143] According to one embodiment of the present invention, in the lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0144] According to one embodiment of the present invention, the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0145] According to one embodiment of the present invention, the negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0146] According to one embodiment of the present invention, a compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO x (0 < x < 2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0147] Additionally, the binder and the conductive material may be the same as those described above for the positive electrode.

[0148] According to one embodiment of the present invention, the negative electrode active material layer may be manufactured by, for example, applying a negative electrode forming composition prepared by dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, onto a negative electrode current collector and drying the coating, or by casting the negative electrode forming composition onto a separate support and then laminating the film obtained by peeling it off from the support onto a negative electrode current collector.

[0149] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used as a separator in lithium secondary batteries can be used without special restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0150] In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0151] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0152] According to one embodiment of the present invention, the organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0153] According to one embodiment of the present invention, the lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable that the concentration of the lithium salt be used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0154] According to one embodiment of the present invention, in addition to the electrolyte components, the electrolyte may further include one or more additives, such as, for example, a haloalkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, a cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0155] According to one embodiment of the present invention, a lithium secondary battery including a cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0156]

[0157] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0158]

[0159] Example 1

[0160] For precursor synthesis, Ni, Co, and Mn sulfate were quantified in a molar ratio of 95:2:3 to a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added to the mixed solvent in appropriate amounts, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0161] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (MgO, TiO2, MoO3, Nb2O5) of each of the four types of heterometal elements (Mg, Ti, Mo, Nb) were weighed so that the molar ratio of Mg / Ti / Mo / Nb was 28.5:28.5:28.5:14.5, and the raw materials of each of the four types of heterometal elements (Mg, Ti, Mo, Nb) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0162]

[0163] Example 2

[0164] For precursor synthesis, Ni, Co, and Mn sulfate were weighed in a molar ratio of 95:2:3 to obtain a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added in appropriate amounts to the mixed solvent, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0165] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (MgO, TiO2, MoO3, V2O5) of each of the four types of heterometal elements (Mg, Ti, Mo, V) were weighed so that the molar ratio of Mg / Ti / Mo / V was 28.5:28.5:28.5:14.5, and the raw materials of each of the four types of heterometal elements (Mg, Ti, Mo, V) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0166]

[0167] Example 3

[0168] For precursor synthesis, Ni, Co, and Mn sulfate were weighed in a molar ratio of 95:2:3 to obtain a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added in appropriate amounts to the mixed solvent, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0169] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (MgO, TiO2, WO3, Nb2O5) of each of the four types of heterometal elements (Mg, Ti, W, Nb) were weighed so that the molar ratio of Mg / Ti / W / Nb was 28.5:28.5:28.5:14.5, and the raw materials of each of the four types of heterometal elements (Mg, Ti, W, Nb) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0170]

[0171] Example 4

[0172] For precursor synthesis, Ni, Co, and Mn sulfate were weighed in a molar ratio of 95:2:3 to obtain a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added in appropriate amounts to the mixed solvent, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0173] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (MgO, TiO2, WO3, V2O5) of each of the four types of heterometal elements (Mg, Ti, W, V) were weighed so that the molar ratio of Mg / Ti / W / V was 28.5:28.5:28.5:14.5, and the raw materials of each of the four types of heterometal elements (Mg, Ti, W, V) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0174]

[0175] Example 5

[0176] For precursor synthesis, Ni, Co, and Mn sulfate were quantified in a molar ratio of 95:2:3 (total concentration of 2.0 M) and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added to the mixed solvent in appropriate amounts, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursor in a molar ratio of 95:2:3.

[0177] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (Al2O3, ZrO2, MoO3, Nb2O5) of each of the four types of heterometal elements (Al, Zr, Mo, Nb) were weighed so that the molar ratio of Al / Zr / W / V was 28.5:28.5:28.5:14.5, and the raw materials of each of the four types of heterometal elements (Al, Zr, W, V) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0178]

[0179] Comparative Example 1

[0180] For precursor synthesis, Ni, Co, and Mn sulfate were weighed in a molar ratio of 95:2:3 to obtain a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added in appropriate amounts to the mixed solvent, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0181] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O in the ratio of 95:2:3 was mixed in the ratio of 1:0.99, and heat treatment was performed at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0182]

[0183] Comparative Example 2

[0184] For precursor synthesis, Ni, Co, and Mn sulfate were weighed in a molar ratio of 95:2:3 to obtain a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added in appropriate amounts to the mixed solvent, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0185] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (MgO, TiO2, Al2O3, Nb2O5) of each of the four types of heterometal elements (Mg, Ti, Al, Nb) were weighed so that the molar ratio of Mg / Ti / Al / Nb was 28.5:28.5:28.5:14.5, and the raw materials of each of the four types of heterometal elements (Al, Zr, W, V) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0186]

[0187] Comparative Example 3

[0188] For precursor synthesis, Ni, Co, and Mn sulfate were weighed in a molar ratio of 95:2:3 to obtain a total concentration of 2.0 M and mixed in distilled water. 5 M NH4OH and 2 M NaOH were added in appropriate amounts to the mixed solvent, and the pH was adjusted to 11-12. The mixture was stirred at a reactor temperature of 50°C to precipitate, and then dried at 120°C for 24 hours to synthesize NiCoMn(OH)2 precursors in a molar ratio of 95:2:3.

[0189] Afterwards, the molar ratio of the NiCoMn(OH)2 precursor with LiOH·H2O at a ratio of 95:2:3 was set to a ratio of 1:0.99, and the raw materials (MgO, TiO2, Nb2O5) of each of the three heterometallic elements (Mg, Ti, Nb) were weighed so that the molar ratio of Mg / Ti / Nb was 40:40:20, and the raw materials of each of the three heterometallic elements (Mg, Ti, Nb) were each added at 1 mol% based on the precursor, mixed, and then heat-treated at 740°C for 13 hours in an oxygen atmosphere to manufacture a cathode active material.

[0190]

[0191] Experimental Example 1 - X-Ray Diffraction Image Analysis

[0192] The particles manufactured in each of Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to XRD analysis using Cu-Kα X-rays to confirm whether a secondary phase or a single phase of the doped High Ni cathode material was formed for actual high-entropy cathode synthesis. For this XRD analysis, an XRD analysis device from Bruker's D8 Endeavor was used.

[0193] Crystal size analysis was performed for each sample using XRD Rietveld analysis, and the correlation between crystal size and capacity retention rate according to doping elements was compared and analyzed.

[0194]

[0195] Experimental Example 2 - Evaluation of Electrochemical Characteristics

[0196] The electrochemical characteristics of the high-entropy High Ni cathode materials manufactured in Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated to determine discharge capacity, life characteristics, rate characteristics, etc., and the correlation between crystal size and capacity retention rate according to doping elements was analyzed through Rietveld analysis of each sample.

[0197]

[0198] The positive electrode active materials, carbon black conductive agents, and PVdF binders manufactured in Examples 1 to 5 and Comparative Examples 1 to 3 were mixed in a weight ratio of 96.25:1.65:2.1 in an N-methylpyrrolidone solvent to manufacture a slurry, which was then applied to one surface of an aluminum current collector, dried at 130°C, and rolled to manufacture an electrode. Afterwards, coin half cells were manufactured to evaluate the 0.1C initial discharge capacity in the voltage range of 3-4.25 V at 25°C, and rate evaluations were conducted through 0.1C, 0.33C, 1C, and 2C discharges, and the coin cells were transferred to a 45°C oven to evaluate the capacity retention rate by charge and discharge at 1C, as shown in Table 1 below.

[0199]

[0200] 0.1C charge / discharge capacity 50 cycle capacity retention rate Rate characteristics Crystal size Example 1 226.19 3.29 5.37 4.8 Example 2 225.89 2.89 5.47 1.4 Example 3 225.49 2.69 5.18 6.5 Example 4 224.99 1.89 4.99 9.3 Example 5 224.89 2.19 4.37 7.1 Comparative example 1 228.48 8.39 4.6 127.3 Comparative example 2223.59 1.29 4.27 8.8 Comparative example 3223.69 0.79 4.87 6.2

[0201] Referring to Table 1 above, it was confirmed that Examples 1 to 4, which include a metal element having an oxidation number of +6, a metal element having an oxidation number of +5, a metal element having an oxidation number of +4, and a metal element having an oxidation number of +3 or +2 in addition to Ni, Co, and Mn, satisfied excellent charge / discharge capacity, capacity retention rate, and rate characteristics.

[0202] Comparative Example 1, which does not contain any metal elements other than Ni, Co, and Mn, was found to have a lower capacity retention rate compared to Examples 1 to 4.

[0203]

[0204] Comparative Example 2, which included four types of metal elements other than Ni, Co, and Mn, but did not include a metal element having an oxidation number of +6, was confirmed to have lower charge / discharge capacity and capacity retention rate compared to Examples 1 to 4.

[0205]

[0206] Comparative Example 3, which included three types of metal elements other than Ni, Co, and Mn, but did not include a metal element having an oxidation number of +6, was confirmed to have lower charge / discharge capacity and capacity retention rate compared to Examples 1 to 4.

Claims

1. As a cathode active material containing nickel-excess metal oxide, The first metallic element having an oxidation number of +6; A second metallic element having an oxidation state of +5; A third metallic element having an oxidation number of +4; and A cathode active material comprising a fourth metal element having an oxidation number of +2 or +3.

2. A cathode active material comprising a lithium composite metal oxide represented by the following chemical formula 1: [Chemical Formula 1] Li a Ni b Co c Mr d M 1 e M 2 f M 3 g M 4 h O2 In the above chemical formula 1, Above M 1 is a member selected from the group consisting of metallic elements having an oxidation state of +6, Above M 2 is a species selected from the group consisting of metallic elements having an oxidation state of +5, Above M 3 is a species selected from the group consisting of metallic elements having an oxidation state of +4, Above M 4 is a member selected from the group consisting of metallic elements having an oxidation state of +2 or +3, 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

3. In paragraph 2, In the above chemical formula 1, the M 1 A cathode active material, wherein the cathode active material is one selected from the group consisting of Cr, Mo, W, and Sg.

4. In paragraph 2, In the above chemical formula 1, the M 2 A cathode active material, wherein the cathode active material is one selected from the group consisting of Nb, V, Ta, and Db.

5. In paragraph 2, Above M 3 A cathode active material, wherein the cathode active material is one selected from the group consisting of Ti, Zr, Hf, and Rf.

6. In paragraph 2, Above M 4 A cathode active material, wherein the cathode active material is one selected from the group consisting of Al, Sc, Y, Mg, Ca, and Sr.

7. In paragraph 2, A positive electrode active material satisfying 0.005≤e≤0.03, 0.005≤f≤0.03, 0.005≤g≤0.03, and 0.005≤h≤0.03 in the above chemical formula 1.

8. In paragraph 2, A positive electrode active material satisfying 0.0025≤e≤0.02, 0.0025≤f≤0.02, 0.0025≤g≤0.02, and 0.0025≤h≤0.02 in the above chemical formula 1.

9. In paragraph 2, The above lithium composite metal oxide is a positive electrode active material represented by the following chemical formula 2: [Chemical Formula 2] Li a Ni b Co c Mr d Mo e No f M 3 g M 4 h O2 In the above chemical formula 2, Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr, 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

10. In paragraph 2, The above lithium composite metal oxide is a positive electrode active material represented by the following chemical formula 3: [Chemical Formula 3] Li a Ni b Co c Mr d Mo e V f M 3 g M 4 h O2 In the above chemical formula 3, Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr, 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

11. In paragraph 2, The above lithium composite metal oxide is a positive electrode active material represented by the following chemical formula 4: [Chemical Formula 4] Li a Ni b Co c Mr d W e No f M 3 g M 4 h O2 In the above chemical formula 4, Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr, 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.

12. In paragraph 2, The above lithium composite metal oxide is a positive electrode active material represented by the following chemical formula 5: [Chemical Formula 5] Li a Ni b Co c Mr d W e V f M 3 g M 4 h O2 In the above chemical formula 5, Above M 3 and M 4 are each different from each other and are one type selected from the group consisting of Ti, Zr, Hf, Rf, Al, Sc, Y, Mg, Ca, and Sr, 0.8≤a≤1.2, 0.8≤b<1.0, 0 <c≤0.09, 0<d≤0.09, 0<e≤0.05, 0<f≤0.05, 0<g≤0.05, 0<h≤0.05이다.