Positive electrode active material and lithium secondary battery containing the same

Abstract

The present disclosure relates to a positive electrode active material and a lithium secondary battery comprising the same. According to one embodiment, a positive electrode active material for a lithium secondary battery is provided, the positive electrode active material comprising metal oxide particles comprising nickel, cobalt, manganese and aluminum, and two doping elements doped into the metal oxide particles.

Description

[Technical Field]

[0001] The present disclosure relates to a positive electrode active material and a lithium secondary battery including the same. [Background technology]

[0002] Recently, in response to the explosive increase in demand for electric vehicles and the demand for increased driving distances, secondary batteries having high capacity and high energy density that can be applied thereto have been actively developed worldwide.

[0003] In particular, to manufacture such a high-capacity battery, a high-capacity positive electrode active material must be used, and therefore, a method of using a nickel-cobalt-manganese-based positive electrode active material with a high nickel content has been proposed.

[0004] However, nickel-cobalt-manganese cathode active materials with a high nickel content have problems such as 1) a decrease in efficiency due to a decrease in capacity, 2) the formation of NiO rock salt structure due to surface oxygen generation and a decrease in cycle characteristics, and 3) an increase in resistance.

[0005] Therefore, there is an urgent need to develop a positive electrode active material that can solve the problems of nickel-cobalt-manganese-based positive electrode active materials that have a high nickel content. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present disclosure is to provide a cathode active material and a lithium secondary battery including the same, which can solve the problem of performance degradation that occurs in cathode active materials with a high nickel content by doping two elements into metal oxide particles containing nickel, cobalt, manganese, and aluminum, and at the same time, can significantly improve electrochemical properties. [Means for solving the problem]

[0007] According to one embodiment, a positive electrode active material for a lithium secondary battery may include metal oxide particles containing nickel, cobalt, manganese, and aluminum, and two doping elements doped into the metal oxide particles.

[0008] The two doping elements may be Nb and Zr.

[0009] The doping amount of Nb may be in the range of 0.0001 mole to 0.01 mole per mole of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0010] The doping amount of Zr may be in the range of 0.001 to 0.007 moles per mole of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0011] The doping amounts of Nb and Zr may satisfy the relationship of the following formula 1.

[0012] 0.3<[Zr] / [Nb]<40 (In formula 1, [Nb] and [Zr] represent the doping amounts of each element based on 1 mole of the total of nickel, cobalt, manganese, aluminum, and the doping element.) The positive electrode active material may be represented by the following Chemical Formula 1:

[0013] [Chemical formula 1] Li a [Ni x Co y Mn z Al h ] 1-t (Nb i Zr j ) t O 2-p X2 p (In the above Chemical Formula 1, X is one or more elements selected from the group consisting of F, N, and P; a is 0.8≦a≦1.3, t is 0.0011≦t≦0.007, 0.6≦x≦0.95, 0 <y≦0.2、0<z≦0.2、0.008≦h≦0.029、0.0011≦i≦0.017、0.9989≦j≦0.983、0≦p≦0.02である) The h may be in the range of 0.01≦h≦0.025.

[0014] The initial diffusion coefficient of the positive electrode active material is 7.30*10 -9 m 2 / sec~8.10*10 -9 m 2 / sec range.

[0015] The grain size of the metal oxide particles may range from 900 Å to 1,550 Å.

[0016] The full width at half maximum (FWHM) value for the (110) plane of the metal oxide particles may range from 0.1890 to 0.2200.

[0017] In the positive electrode active material for a lithium secondary battery, when an X-ray diffraction pattern is measured, I(003) / I(104), which is a peak intensity ratio of the (003) plane to the peak intensity of the (104) plane, may be in the range of 1.2300 to 1.2410.

[0018] The content of nickel in the metal oxide particles may be 0.8 moles or more based on 1 mole of the total of nickel, cobalt, and manganese.

[0019] A lithium secondary battery according to another embodiment may include a positive electrode including a positive electrode active material according to an embodiment, a negative electrode, and a non-aqueous electrolyte. [Effects of the Invention]

[0020] When the positive electrode active material according to the present disclosure is applied by doping at least two elements into metal oxide particles containing NCMA, it can increase the capacity of a lithium secondary battery while significantly improving the room temperature and high temperature life characteristics, initial efficiency, initial resistance, resistance increase rate, and thermal stability. DETAILED DESCRIPTION OF THE INVENTION

[0021] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Therefore, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0022] The terminology used herein is merely for the purpose of referring to particular embodiments and is not intended to limit the present invention. As used herein, the singular form includes the plural form unless the context clearly dictates otherwise. As used in the specification, the meaning of "comprising" embodies certain properties, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other properties, regions, integers, steps, operations, elements, and / or components.

[0023] When a part is referred to as being "on" another part, it means that it is immediately on top of the other part, or there may be other parts between them. In contrast, when a part is referred to as being "directly on top of" another part, there are no other parts between them.

[0024] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries are additionally interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless otherwise defined.

[0025] According to one embodiment, a positive electrode active material for a lithium secondary battery may include metal oxide particles containing nickel, cobalt, manganese, and aluminum, and two doping elements doped into the metal oxide particles.

[0026] In this case, the two doping elements can be Nb and Zr.

[0027] In order to dope lithium metal oxides and ensure their longevity and various electrochemical performances, it is important to select the doping element. Known doping elements to date include Ag. + , Na + Monovalent ions such as Co 2+ , Cu 2+ , Mg 2+ , Zn 2+ , Ba 2+ , Al 3+ , Fe 3+ , Cr 3+ , Ga 3+ , Zr 4+ , Ti 4+ These elements have different effects on the battery life and output characteristics.

[0028] In this embodiment, by including Nb and Zr in such doping elements, it is possible to improve the room temperature and high temperature life characteristics and thermal stability while ensuring high capacity, and to improve the initial capacity and initial efficiency.

[0029] Specifically, Zr 4+In this case, Zr ions occupy the Li site, acting as a kind of pillar, mitigating the contraction of the lithium ion path during the charge / discharge process and stabilizing the layered structure. This phenomenon reduces cation mixing, increases the lithium diffusion coefficient, and can extend the cycle life.

[0030] Nb can improve the life characteristics and at the same time effectively reduce the rate of increase in resistance.

[0031] In this embodiment, the Nb doping amount may be in the range of 0.0001 mol to 0.01 mol, more specifically, 0.00025 mol to 0.01 mol or 0.0005 mol to 0.0025 mol, per 1 mol of the total of nickel, cobalt, manganese, aluminum, and the doping element. When the Nb doping amount satisfies this range, significant advantages can be achieved in that the room temperature life, high temperature life, and average leakage current value of the lithium secondary battery can all be improved. Furthermore, the diffusion coefficient of the lithium secondary battery can be increased, thereby effectively reducing the resistance increase rate during impedance analysis.

[0032] The doping amount of Zr may be in the range of 0.001 to 0.007 mol, more specifically, 0.002 to 0.005 mol or 0.0035 to 0.005 mol, per 1 mol of the total of nickel, cobalt, manganese, aluminum, and the doping element. When the doping amount of Zr satisfies this range, the high-temperature life and room-temperature life characteristics of the lithium secondary battery can be significantly improved.

[0033] In this embodiment, the doping amounts of Nb and Zr may satisfy the relationship of the following formula 1.

[0034] [Formula 1] 0.3≦[Zr] / [Nb]≦40 In formula 1, [Nb] and [Zr] represent the doping amounts of each element based on 1 mole of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0035] More specifically, Formula 1 may be in the range of 0.35 or more and 35 or less, 0.7 or more and 14 or less, or 1.4 or more and 7 or less.

[0036] When the formula 1 satisfies the above range, the effect of improving the surface conductivity of the Zr and Nb cathode material and the effect of the surface protective film are improved, thereby improving the room temperature initial capacity and high temperature life.

[0037] The positive electrode active material for a lithium secondary battery according to the present embodiment may be represented by the following Chemical Formula 1.

[0038] [Chemical formula 1] Li a [Ni x Co y Mn z Al h ] 1-t (Nb i Zr j ) t O 2-p X2 p In the above Chemical Formula 1, X is one or more elements selected from the group consisting of F, N, and P; a is 0.8≦a≦1.3, t is 0.0011≦t≦0.007, 0.6≦x≦0.95, 0 <y≦0.2、0<z≦0.2、0.008≦h≦0.029、0.0011≦i≦0.017、0.9989≦j≦0.983、0≦p≦0.02である。

[0039] In this embodiment, the Al content range h may be 0.008 to 0.029, more specifically, 0.01≦h≦0.025. When the Al content satisfies this range, a lithium secondary battery with excellent initial efficiency and thermal stability and significantly improved room temperature and high temperature lifespans can be achieved.

[0040] In addition, in this embodiment, the content of the nickel may be 0.8 mol or more based on 1 mol of the total of the nickel, cobalt, manganese, and aluminum, and more specifically, may be in the range of 0.8 mol to 0.99 mol, 0.82 mol to 0.95 mol, or 0.83 mol to 0.92 mol.

[0041] When the nickel content is 0.8 moles or more based on the total mole of nickel, cobalt, manganese, and aluminum in the metal oxide, as in this embodiment, a positive electrode active material with high output characteristics can be realized. The positive electrode active material of this embodiment having such a composition has a high energy density per volume, which can improve the capacity of the battery to which it is applied, and is also suitable for use in electric vehicles.

[0042] On the other hand, the initial diffusion coefficient of the positive electrode active material according to this embodiment is 7.30*10 -9 m 2 / sec~8.10*10 -9 m 2 / sec, more specifically, 7.57*10 -9 m 2 / sec~8.05*10 -9 m 2 / sec, 7.60*10 -9 m 2 / sec~8.05*10 -9 m 2 / sec, or 7.86*10 -9 m 2 / sec~8.05*10 -9 m 2 / sec range. When the initial diffusion coefficient is in this range, the movement of Li ions in the positive electrode active material is effective, which increases the initial capacity and rate characteristics of the positive electrode material. On the other hand, when the diffusion coefficient is 7.57*10 -9 m 2 / sec, the resistance in the cathode material increases, which significantly reduces the cycle characteristics. -9 m 2If it exceeds 1 / sec, the structure becomes unstable and the cycle characteristics deteriorate.

[0043] Next, the crystal grain size of the metal oxide particles may be in the range of 900 Å to 1,550 Å, more specifically, 950 Å to 1,500 Å, 1,050 Å to 1,32 Å, and more specifically, 1,050 Å to 1,287 Å. When the crystal grain size satisfies the above range, high-temperature life is improved without a decrease in initial capacity.

[0044] In addition, the full width at half maximum (FWHM) value of the (110) plane of the metal oxide particles may be in the range of 0.1890 to 0.2200, more specifically, 0.1895 to 0.2041, or 0.1916 to 0.2041. When the full width at half maximum (FWHM) value of the (110) plane satisfies this range, the high-temperature life is significantly improved.

[0045] In the positive electrode active material of this embodiment, when measuring the X-ray diffraction pattern, the peak intensity ratio of the (003) plane to the peak intensity of the (104) plane, I(003) / I(104), may be in the range of 1.2300 to 1.2410, more specifically, 1.2315 to 1.2406 or 1.2330 to 1.2406.

[0046] Generally, the peak intensity value refers to the height value of a peak or the integrated area value obtained by integrating the area of ​​a peak, and in this embodiment, the peak intensity value refers to the area value of a peak.

[0047] When the peak intensity ratio I(003) / I(104) is within the above range, the structural stabilization is enhanced without a decrease in capacity, thereby improving the thermal stability of the positive electrode active material.

[0048] In addition, the peak intensity ratio I(003) / I(104) is a cation mixing index, and as the I(003) / I(104) value decreases, the initial capacity and rate characteristics of the positive electrode active material may decrease. However, in this embodiment, since the I(003) / I(104) ratio is in the range of 1.220 to 1.240, a positive electrode active material with excellent capacity and rate characteristics can be realized.

[0049] Meanwhile, the positive electrode active material of this embodiment may be bimodal, consisting of a mixture of large and small particles. The large particles may have an average particle size (D50) of 10 μm to 20 μm, and the small particles may have an average particle size (D50) of 3 μm to 7 μm. The large and small particles may also be in the form of secondary particles formed by granulation of at least one primary particle. The mixing ratio of the large and small particles may be 50 to 80 wt % of the large particles, based on a total of 100 wt %. This bimodal particle distribution can improve energy density.

[0050] In another embodiment of the present invention, there is provided a lithium secondary battery including a positive electrode including the positive electrode active material according to the embodiment of the present invention, a negative electrode including the negative electrode active material, and an electrolyte disposed between the positive electrode and the negative electrode.

[0051] The description of the positive electrode active material is omitted because it is the same as that of the above-described embodiment of the present invention.

[0052] The positive electrode active material layer may include a binder and a conductive material.

[0053] The binder serves to adhere the positive electrode active material particles to each other and to the current collector.

[0054] The conductive material is used to impart conductivity to the electrode, and in the battery being configured, any electron conductive material that does not cause a chemical change can be used.

[0055] The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer contains a negative electrode active material.

[0056] Examples of the negative electrode active material include substances capable of reversibly inserting / desorbing lithium ions, lithium metal, alloys of lithium metal, substances capable of doping and undoping lithium, or transition metal oxides.

[0057] Examples of the substances capable of reversibly inserting / desorbing lithium ions include carbon substances, and any carbon-based negative electrode active material generally used in lithium ion secondary batteries can be used. Representative examples thereof include crystalline carbon, amorphous carbon, or both can be used.

[0058] Examples of the alloy of lithium metal include alloys of lithium and metals selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0059] Examples of the substances capable of doping and undoping lithium include Si, SiO x (0 < x < 2), Si-Y alloys (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof and is not Si), Sn, SnO2, Sn-Y (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof and is not Sn), etc.

[0060] Examples of the transition metal oxide include vanadium oxide, lithium vanadium oxide, etc. The negative electrode active material layer also includes a binder, and may optionally further include a conductive material.

[0061] The binder serves to effectively adhere the negative electrode active material particles to each other and to the current collector.

[0062] The conductive material is used to impart electrical conductivity to the electrodes, and any electron-conductive material that does not undergo chemical change in the battery that is constructed can be used.

[0063] The current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0064] The negative and positive electrodes are fabricated by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and then coating the composition on a current collector. Since this electrode fabrication method is widely known in the art, a detailed description thereof will be omitted. Examples of the solvent include, but are not limited to, N-methylpyrrolidone.

[0065] The electrolyte includes a non-aqueous organic solvent and a lithium salt.

[0066] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can migrate.

[0067] The lithium salt is dissolved in an organic solvent and acts as a lithium ion source in the battery, enabling basic operation of a lithium secondary battery, and promoting the movement of lithium ions between the positive electrode and the negative electrode.

[0068] Depending on the type of lithium secondary battery, a separator may be present between the positive electrode and the negative electrode. Such a separator may be made of polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more of these materials. Of course, mixed multilayer films such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may also be used.

[0069] Lithium secondary batteries can be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries depending on the type of separator and electrolyte used, into cylindrical, prismatic, coin, pouch, etc. types depending on the shape, and into bulk and thin film types depending on the size. The structures and manufacturing methods of these batteries are widely known in the art, so detailed explanations will be omitted. [Example]

[0070] The following examples of the present invention are described in detail, but are presented by way of example only and are not intended to limit the scope of the present invention, which is defined only by the scope of the claims that follow.

[0071] Preparation Example 1 - Preparation of NCM precursor The positive electrode active material precursor was produced by a common coprecipitation method.

[0072] NiSO4·6H2O was used as the nickel source material, CoSO4·7H2O was used as the cobalt source material, and MnSO4·H2O was used as the manganese source material. These raw materials were dissolved in distilled water to prepare metal salt aqueous solutions.

[0073] After preparing the coprecipitation reactor, N2 was purged to prevent oxidation of metal ions during the coprecipitation reaction, and the reactor temperature was maintained at 50°C.

[0074] NH4(OH) was added to the co-precipitation reactor as a chelating agent, and NaOH was used to adjust the pH. The precipitate obtained by the co-precipitation process was filtered, washed with distilled water, and dried in a cake dryer at 180°C to prepare a cathode active material precursor.

[0075] The composition of the produced precursor was (Ni 0.92 Co 0.04 Mn 0.04 )(OH)2, the average particle size (D50) of the large particle size precursor was 14.3 μm, and the average particle size (D50) of the small particle size precursor was 4.5 μm.

[0076] Example 1 - 0.0035 mol Zr + 0.0001 mol Nb doping The precursor prepared in Preparation Example 1, the lithium source, the aluminum source, and the doping source were uniformly mixed and then fired in a tube furnace under an oxygen atmosphere. The firing conditions were 480°C for 5 hours, followed by 15 hours at 740-780°C, with a temperature increase rate of 5°C / min.

[0077] The lithium source used was LiOH·H2O (Samchun Chemical, battery grade), the aluminum source was Al(OH)3 (Aldrich, 3N), and the doping sources were ZrO2 (Aldrich, 3N) and Nb2O5 (Aldrich, 3N).

[0078] At this time, the doping amount is LiNi 0.90 Co 0.04 Mn 0.04 Al 0.02 M=Ni based on O2 0.90 Co 0.04 Mn 0.04 Al 0.02 The amount of doping material added was adjusted so that the sum of M and the doped amount was 1 mol. In other words, Li(M) 1-x (D) xThe overall composition of the large particle size and small particle size positive electrode active materials doped with the two elements is Li(M) 0.9964 Zr 0.0035 Nb 0.0001 It was O2.

[0079] The fired large particle size and small particle size positive active materials were uniformly mixed in a weight ratio of 80:20 (large particle size:small particle size) to prepare a bimodal positive active material of Example 1.

[0080] Comparative Example 1 - NCMA + Zr doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the doping amount was adjusted using the precursor prepared in Preparation Example 1.

[0081] The overall composition of the large particle size and small particle size positive electrode active materials prepared in Comparative Example 1 was Li(M) 0.9965 Zr 0.0035 It was O2.

[0082] Example 2 - 0.0035 mol Zr + 0.00025 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0083] The overall composition of the positive electrode active material prepared in Example 2 was Li(M) 0.99625 Zr 0.0035 Nb 0.00025 It was.

[0084] Example 3 - 0.0035 mol Zr + 0.0005 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0085] The overall composition of the positive electrode active material prepared in Example 3 was Li(M) 0.996 Zr 0.0035 Nb 0.0005 It was.

[0086] Example 4 - 0.0035 mol Zr + 0.001 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0087] The overall composition of the positive electrode active material prepared in Example 4 was Li(M) 0.9955 Zr 0.0035 Nb 0.001 It was.

[0088] Example 5 - 0.0035 mol Zr + 0.0025 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0089] The overall composition of the positive electrode active material prepared in Example 5 was Li(M) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0090] Reference Example 1 - 0.0035 mol Zr + 0.005 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0091] The overall composition of the positive electrode active material prepared in Reference Example 1 was Li(M) 0.9915 Zr 0.0035 Nb 0.005 It was.

[0092] Reference Example 2 - 0.0035 mol Zr + 0.01 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0093] The overall composition of the positive electrode active material prepared in Reference Example 2 was Li(M) 0.9865 Zr 0.0035 Nb 0.01 It was.

[0094] Example 6 - 0.002 mol Zr + 0.0025 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0095] The overall composition of the positive electrode active material prepared in Example 6 was Li(M) 0.9955 Zr 0.002 Nb 0.0025 It was.

[0096] Example 7 - 0.005 mol Zr + 0.0025 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0097] The overall composition of the positive electrode active material prepared in Example 7 was Li(M) 0.9925 Zr 0.005 Nb 0.0025 It was.

[0098] Reference Example 3 - 0.008 mol Zr + 0.0025 mol Nb doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor prepared in Preparation Example 1 was used and the amount of doping material was adjusted.

[0099] The overall composition of the positive electrode active material prepared in Reference Example 3 was Li(M) 0.9895 Zr 0.008 Nb0.0025 It was.

[0100] Reference Example 4 - 0.0035 mol Zr + 0.0025 mol Nb doping + 0.005 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted using the precursor prepared in Preparation Example 1.

[0101] The overall composition of the positive electrode active material prepared in Reference Example 4 was Li(Ni 0.915 Co 0.04 Mn 0.04 Al 0.005 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0102] Example 8 - 0.0035 mol Zr + 0.0025 mol Nb doping + 0.01 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted using the precursor prepared in Preparation Example 1.

[0103] The overall composition of the positive electrode active material prepared in Example 8 was Li(Ni 0.91 Co 0.04 Mn 0.04 Al 0.01 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0104] Example 9 - 0.0035 mol Zr + 0.0025 mol Nb doping + 0.015 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted using the precursor prepared in Preparation Example 1.

[0105] The overall composition of the positive electrode active material prepared in Example 9 was Li(Ni 0.905 Co0.04 Mn 0.04 Al 0.015 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0106] Example 10 - 0.0035 mol Zr + 0.0025 mol Nb doping + 0.025 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted using the precursor prepared in Preparation Example 1.

[0107] The overall composition of the positive electrode active material prepared in Example 10 was Li(Ni 0.895 Co 0.04 Mn 0.04 Al 0.025 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0108] Reference Example 5 - 0.0035 mol Zr + 0.0025 mol Nb doping + 0.03 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted using the precursor prepared in Preparation Example 1.

[0109] The overall composition of the positive electrode active material prepared in Reference Example 5 was Li(Ni 0.89 Co 0.04 Mn 0.04 Al 0.025 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0110] The doping amounts and overall compositions of the positive electrode active materials prepared in Comparative Example 1, Examples 1 to 10, and Reference Examples 1 to 5 are as shown in the table below.

[0111] [Table 1]

[0112] Comparative Example 2 - 0.78 mol Ni + 0.0035 mol Zr + 0.02 mol Al doping In the same manner as in Production Example 1, (Ni 0.80 Co 0.10 Mn 0.10 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0113] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0114] The overall composition of the positive electrode active material prepared in Comparative Example 2 was Li(Ni 0.78 Co 0.10 Mn 0.10 Al 0.02 ) 0.9965 Zr 0.0035 It was.

[0115] Comparative Example 3 - 0.81 mol Ni + 0.0035 mol Zr + 0.02 mol Al doping In the same manner as in Production Example 1, (Ni 0.83 Co 0.12 Mn 0.05 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0116] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0117] The overall composition of the positive electrode active material prepared in Comparative Example 3 was Li(Ni 0.81 Co 0.12 Mn 0.05 Al 0.02 ) 0.9965 Zr 0.0035 It was.

[0118] Comparative Example 4 - 0.83 mol Ni + 0.0035 mol Zr + 0.02 mol Al doping In the same manner as in Production Example 1, (Ni 0.85 Co 0.075 Mn 0.075 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0119] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0120] The overall composition of the positive electrode active material prepared in Comparative Example 4 was Li(Ni 0.83 Co 0.075 Mn 0.075 Al 0.02 ) 0.9965 Zr 0.0035 It was.

[0121] Comparative Example 5 - 0.84 mol Ni + 0.0035 mol Zr + 0.02 mol Al doping In the same manner as in Production Example 1, (Ni 0.86 Co 0.07 Mn 0.07 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0122] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0123] The overall composition of the positive electrode active material prepared in Comparative Example 5 was Li(Ni 0.84 Co 0.07 Mn 0.07 Al 0.02 ) 0.9965 Zr 0.0035 It was.

[0124] Comparative Example 6 - 0.86 mol Ni + 0.0035 mol Zr + 0.02 mol Al doping In the same manner as in Production Example 1, (Ni 0.88 Co 0.05 Mn 0.07 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0125] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0126] The overall composition of the positive electrode active material prepared in Comparative Example 6 was Li(Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 ) 0.9965 Zr 0.0035 It was.

[0127] Reference Example 6 - 0.78 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doping + 0.02 mol Al In the same manner as in Production Example 1, (Ni 0.80 Co 0.10 Mn 0.10 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0128] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0129] The overall composition of the positive electrode active material prepared in Reference Example 6 was Li(Ni 0.78 Co 0.01 Mn 0.01 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0130] Reference Example 7 - 0.81 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doping + 0.02 mol Al In the same manner as in Production Example 1, (Ni 0.83 Co 0.12 Mn 0.05 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0131] Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted.

[0132] The overall composition of the positive electrode active material prepared in Reference Example 7 was Li(Ni 0.81 Co 0.12 Mn 0.05 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0133] Example 11 - 0.83 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doping + 0.02 mol Al In the same manner as in Production Example 1, (Ni 0.85 Co 0.075 Mn 0.075 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0134] Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amount of aluminum raw material and the amount of doping raw material were adjusted.

[0135] The overall composition of the positive electrode active material prepared in Example 11 was Li(Ni 0.83 Co 0.075 Mn 0.075 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0136] Example 12 - 0.84 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doping + 0.02 mol Al In the same manner as in Production Example 1, (Ni 0.86 Co 0.07 Mn 0.07 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0137] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0138] The overall composition of the positive electrode active material prepared in Example 12 was Li(Ni 0.84 Co 0.07 Mn 0.07 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0139] Example 13 - 0.86 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doping + 0.02 mol Al In the same manner as in Production Example 1, (Ni 0.88 Co 0.05 Mn 0.07 Large and small particle size precursors with the )(OH)2 composition were prepared.

[0140] Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the doping material was adjusted using the precursor.

[0141] The overall composition of the positive electrode active material prepared in Example 13 was Li(Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0142] The doping amounts and overall compositions of Comparative Examples 2 to 6, Reference Examples 6 and 7, and Examples 11 to 13 are as shown in the table below.

[0143] [Table 2]

[0144] Experimental Example 1 - XRD analysis results The lattice constants of the positive electrode active materials prepared in Examples 1 to 5, Reference Examples 1 and 2, and Comparative Example 1 were measured by X-ray diffraction using CuKα radiation. The measured a-axis length, b-axis length, and c-axis length are shown in Table 3 below.

[0145] The unit cell volume and crystalline size of the active material were also measured and are shown in Table 3 below.

[0146] Next, Rietveld analysis was performed using the commercial software High Score Plus 4.0 program for crystallographic considerations of doping, and the results are shown in Table 3. XRD measurements were performed in the range of 10° to 130°, and fitting was performed using the Rietveld refinement method. The Goodness of Fitness (GOF) values ​​matched within 2.0.

[0147] The intensities (peak areas) of the (003) and (104) planes and the intensity of the (110) plane were measured using an XRD device (Panalytical's X'pert3 powder diffraction) at a scan speed (° / s) of 0.328. From these results, the I(003) / I(104) and full width at half maximum (FWHM) of the (110) plane were calculated and are shown in Table 3.

[0148] Furthermore, it was confirmed that both measured samples had a well-developed (003) plane as the main peak around 18.7°, and splitting of the (006) / (102) peak between 37.5° and 38.5°, and the (108) / (110) peak between 63.5° and 35.5° appeared. This indicated that the samples had good crystalline ordering of hexagonal layers and exhibited a typical α-NaFeO2 (space group R-3m) structure.

[0149] [Table 3]

[0150] Referring to Table 3, it can be seen that the XRD analysis results and the crystalline structure factor values ​​change depending on whether or not Nb is doped and the amount of Nb doping.

[0151] Specifically, when compared with the cathode active material of Comparative Example 1 in which Zr and Al were doped into the NCM active material, it was confirmed that as the amount of Nb doped into the NCMA was increased, the full width at half maximum (FWHM) value of the (110) plane increased and the crystal grain size decreased.

[0152] Additionally, the crystal structure constants a, b, and c, as well as the unit cell volume, were found to have their maximum values ​​in Example 5. The intensity ratio of (003) / (104), which indicates the cation mixing index, was found to decrease with increasing Nb doping. This phenomenon is believed to be due to Nb doping at the lithium site, weakening the peak intensity of the (003) plane, which indicates the Li site, in the XRD peak. However, given that the a and c values ​​increase and the unit cell volume increases in some doping compositions, it is possible to confirm the existence of a region where Nb doping maximizes the crystallinity of the positive electrode active material.

[0153] That is, it can be confirmed that the doping amount of Nb can be in the range of 0.0001 mol to 0.0025 mol, and is preferably in the range of 0.0005 mol to 0.0025 mol.

[0154] Experimental Example 2 - Electrochemical Evaluation (1) Manufacturing of coin-type half cells A CR2032 coin cell was fabricated using the cathode active material prepared as described above, and then electrochemical evaluation was carried out.

[0155] Specifically, the positive electrode active material, conductive material (Denka Black), and polyvinylidene fluoride binder (product name: KF1100) were mixed in a weight ratio of 92.5:3.5:4, and this mixture was added to N-methyl-2-pyrrolidone solvent so that the solid content was approximately 30 wt % to prepare a positive electrode active material slurry.

[0156] The slurry was coated on an aluminum foil (thickness: 15 μm) as a positive electrode current collector using a doctor blade, dried, and then rolled to prepare a positive electrode. The loading amount of the positive electrode was about 14.6 mg / cm. 2 The rolling density is approximately 3.1 g / cm 3 It was.

[0157] A 2032 coin-type half-cell was fabricated using the cathode, lithium metal anode (300 μm thick, MTI), electrolyte, and polypropylene separator in a conventional manner. The electrolyte was prepared by dissolving 1M LiPF6 in a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (EMC) (mixing ratio EC:DMC:EMC = 3:4:3 vol%) to prepare a mixed solution, to which 3 wt% vinylene carbonate (VC) was added.

[0158] (2) Evaluation of charge / discharge characteristics The coin-type half cell prepared in (1) above was aged at room temperature (25° C.) for 10 hours, and then a charge / discharge test was carried out.

[0159] The capacity was evaluated using 205 mAh / g as the reference capacity, and the charge / discharge conditions were constant current (CC) / constant voltage (CV) 2.5 V to 4.25 V, with a 1 / 20 C cut-off.

[0160] The initial capacity was measured after 0.1C charge / 0.1C discharge, and the initial efficiency was calculated after 0.2C charge / 0.2C discharge. The results are shown in Table 4 below.

[0161] (3) Measurement of life characteristics The room temperature cycle life characteristics were measured 30 times at room temperature (25°C), and the high temperature cycle life characteristics were measured at high temperature (45°C) under 0.3C charge / 0.3C discharge conditions.

[0162] (4) Measurement of resistance characteristics The room temperature initial resistance (DC-IR (Direct current internal resistance)) was calculated by charging the battery at 0.2C and discharging it at 0.2C once under the conditions of constant current-constant voltage 2.5V to 4.25V with 1 / 20C cut-off at 25°C, and measuring the voltage value 60 seconds after applying a discharge current at 4.25V (100% charge).

[0163] The resistance increase rate was measured by comparing the resistance measured initially at room temperature (25°C) (room temperature initial resistance) with the resistance after 30 cycles in the same manner as in the initial resistance measurement method, and the increase rate was converted into a percentage (%).

[0164] The average leakage current was measured by measuring the current generated over 120 hours while maintaining the half cell at 4.7 V at a high temperature of 45° C. and calculating the average value.

[0165] (5) Evaluation of thermal stability For differential scanning calorimetry (DSC) analysis, the half-cell was initially charged to 4.25 V at 0.1 C charge conditions, then disassembled to separate the cathode, which was then washed five times with dimethyl carbonate. The washed cathode was then immersed in an electrolyte in a DSC crucible, and the temperature was raised to 265°C. The calorific value was measured using a Mettler Toledo DSC1 star system, and the resulting DSC peak temperature was recorded.

[0166] Experimental Example 2-1. Effects of Nb inclusion and content The electrochemical properties of the positive electrode active materials prepared in Examples 1 to 5, Reference Examples 1 and 2, and Comparative Example 1 were evaluated by the method of Experimental Example 2, and the results are shown in Table 4 below.

[0167] [Table 4]

[0168] Examples 1 to 5 and Reference Examples 1 and 2 show the results of measuring the electrochemical properties depending on the doping amount when an Al raw material was mixed with a precursor having an Ni content of 90 mol % or more and doped with both Zr and Nb.

[0169] Referring to Table 4, it can be seen that the cathode active materials of Examples 1 to 5, in which an NCMA cathode active material was prepared by mixing an Al raw material with an NCM precursor and doping Zr and Nb, exhibited significantly increased discharge capacity and initial capacity compared to the cathode active material of Comparative Example 1, in which 2 mol % of Al and Zr were doped into NCM.

[0170] Also, when Nb is doped together with Zr as in Examples 1 to 5, it can be seen that the room temperature life, high temperature life, resistance increase rate, and average leakage current value are all improved.

[0171] This indicates that the problem of rapid decrease in discharge capacity and initial efficiency, which occurred in the conventional cathode active material doped with Al and Zr by adding 0.01 mol or more of Al, has been significantly improved.

[0172] In particular, in the case of Examples 3 to 5, in which the Nb content is in the range of 0.0001 mol to 0.0025 mol, it can be confirmed that the improvements in discharge capacity, initial efficiency, room temperature life, high temperature life, room temperature resistance, resistance increase rate, leakage current, and DSC peak temperature are significantly improved compared to Comparative Example 1.

[0173] Experimental Example 2-2. Effect of Zr content The electrochemical properties of the positive electrode active materials prepared in Examples 6 and 7 and Reference Example 3 were evaluated by the method of Experimental Example 2 and the results are shown in Table 5. For comparison, the results of Example 5 are also shown.

[0174] [Table 5]

[0175] In Examples 6 and 7 and Reference Example 3, the amount of aluminum raw material introduced was fixed at 0.02 mol, and the amount of Nb doped was fixed at 0.0025 mol, while only the amount of Zr doped was changed.

[0176] Referring to Table 5, it can be seen that as the doping amount of Zr increases from 0.002 mol to 0.008 mol, some properties improve and some properties deteriorate.

[0177] Specifically, the results of Examples 5 to 7 show that the higher the Zr doping amount, the better the high-temperature and room-temperature lifespans. However, when the Zr doping amount is increased to 0.008 mol as in Reference Example 3, the discharge capacity and initial efficiency are significantly reduced.

[0178] Therefore, the suitable doping amount of Zr in this embodiment may be in the range of 0.001 mol to 0.007 mol, specifically 0.002 mol to 0.005 mol or 0.0035 mol to 0.005 mol, per 100 mol of nickel, cobalt, manganese and doping element.

[0179] Experimental Example 2-3. Effect of Al content The electrochemical properties of the positive electrode active materials prepared in Examples 8 to 10 and Reference Examples 4 and 5 were evaluated by the method of Experimental Example 2 and the results are shown in Table 6. For comparison, the results of Example 5 are also shown.

[0180] [Table 6]

[0181] In Examples 8 to 10 and Reference Examples 4 and 5, the doping amounts were fixed at Zr 0.0035 mol and Nb 0.0025 mol, and only the amount of Al raw material was changed.

[0182] Referring to Table 6, it can be seen that as the amount of Al raw material increases from 0.005 mol to 0.03 mol, the room temperature life and high temperature life are significantly increased, the room temperature initial resistance, resistance increase rate, and leakage current are decreased, and the DSC peak temperature is increased.

[0183] Specifically, the capacity tended to decrease as the amount of Al raw material increased, but the initial efficiency of the positive electrode active materials of Examples 8 to 10, in which the amount of Al raw material was 0.01 mol or more, was significantly improved to 93% or more by doping with Nb.

[0184] In addition, as shown in Comparative Example 1 in Table 4, when Nb is not doped, the initial efficiency is about 90%, but when Nb is doped, it can be confirmed that the initial efficiency is significantly improved.

[0185] However, in Reference Example 4, where the amount of Al raw material mixed was 0.005 mol, the DSC peak temperature was very low at 220°C, and the room temperature and high temperature lifespans were significantly reduced. Also, in Reference Example 5, where the amount of Al raw material mixed was 0.03 mol, the discharge capacity was significantly reduced, and therefore the initial efficiency was also significantly reduced.

[0186] Therefore, in this embodiment, the amount of aluminum source may range from 0.008 mole to 0.029 mole, more specifically, from 0.01 mole to 0.025 mole, per 100 moles of nickel, cobalt, manganese, and aluminum.

[0187] Experimental Example 2-4. Effect of Ni content The electrochemical properties of the cathode active materials prepared in Comparative Examples 2 to 6, Reference Examples 6 and 7, and Examples 11 to 13 were evaluated by the method of Experimental Example 2 and the results are shown in Table 7 below. For comparison, the results of Comparative Example 1 and Example 5 are also shown.

[0188] [Table 7]

[0189] Comparative Examples 1 to 6 are positive electrode active materials in which an NCM precursor is doped with Zr and Al, and Reference Examples 6 to 7 and Examples 11 to 13 are positive electrode active materials produced by mixing an Al raw material and a Zr- and Nb-doped raw material with an NCM precursor.

[0190] Referring to Table 7, it can be seen that when the Ni content is less than 83% as in Reference Examples 6 and 7, the addition of Nb rather significantly reduces the discharge capacity and initial efficiency.

[0191] On the other hand, when the Ni content is 83% or more, the addition of Nb can significantly increase the discharge capacity and initial efficiency.

[0192] This is believed to be because, although the resistance characteristics of Nb itself are higher than those that occur when the Ni content is low, they are lower than the resistance characteristics that occur as the Ni content increases, thereby offsetting the rapid increase in resistance that occurs when the Ni content is 83% or higher. In other words, in the case of high-nickel NCM cathode materials, the rapid increase in resistance that occurs with an increase in Ni appears to be suppressed to some extent by Nb doping. This results in overall improvements in high-temperature lifespan, room-temperature lifespan, and resistance increase rate. In conclusion, when NCMA products with a Ni content of 83% or higher are doped with binary materials containing Nb, the effects of increased discharge capacity and initial efficiency are significantly greater, and other physical properties are also improved overall.

[0193] Experimental Example 3 - Diffusion Coefficient and Impedance Analysis The positive electrode active materials prepared in Examples 1 to 5, Reference Examples 1 and 2, and Comparative Example 1 were subjected to diffusion coefficient and impedance analysis, and the results are shown in Table 8 below.

[0194] The diffusion coefficient was measured using the GITT method. After charging for 30 minutes, the battery was maintained for 50 minutes. The data obtained at this time was analyzed using the following equation 2.

[0195] [Formula 2]

[0196]

number

[0197] In Equation 2, V M : Molar volume of positive electrode active material A: Electrode area when measuring the diffusion coefficient F: Faraday constant Z Li :+1 I o :0.1C x: fraction of lithium present in the electrode dE s : The voltage change amount obtained in the maintenance section, dE t : Voltage change obtained during the charging section t: time (sec) Specifically, the molar volume of the positive electrode active material was calculated using the unit volume analyzed through the XRD measurement results. A is the electrode area when measuring the diffusion coefficient. In the case of the coin cell used in this diffusion coefficient measurement, the area was 1.538 cm. 2 It has a size of I o means a 0.1C current value. X can be calculated assuming the entire charge / discharge interval is 100%. For example, x corresponding to the first 30-minute charge interval can be expressed as 0.05, x corresponding to the second 30-minute charge interval can be expressed as 0.1, and x corresponding to the intermediate interval can be expressed as 0.5.

[0198] The impedance analysis was performed using an impedance graph obtained at 3.7V, and the results are shown in Table 8 below, along with the diffusion coefficient. The obtained impedance values ​​were separated into real and imaginary axes, and a Nyquist plot was made. The resulting figure was divided into two semicircular shapes and fitted to obtain the R sei and R ct At this time, the resistance value obtained by the semicircle generated in the high frequency region was calculated as R sei The resistance obtained by the semicircle generated in the low frequency region is named R ct and the resistance value was calculated.

[0199] [Table 8]

[0200] The diffusion coefficient was measured based on Equation 2. As shown in Table 8, the diffusion coefficient was 10 -9 It was confirmed that the order of

[0201] Furthermore, it was confirmed that there is a region in which the diffusion coefficient increases with additional Nb doping in the Examples, and that the diffusion coefficient increases up to a certain level when additional Nb is doped compared to the Comparative Examples. The phenomenon of the diffusion coefficient increasing with Nb doping means that Nb is introduced into the cathode material and promotes Li migration within the cathode material, which may result in improved rate characteristics and initial capacity. However, if too much Nb is doped, it may actually hinder Li migration, lowering the diffusion coefficient and resulting in poor rate characteristics and capacity characteristics. Therefore, it can be seen that the diffusion coefficient decreases slightly in Reference Examples 1 and 2, where 0.005 mol and 0.01 mol of Nb were doped, respectively.

[0202] Meanwhile, referring to Table 8 in relation to the impedance measurement, in Examples 1 to 5 in which a binary doping material was applied to NCMA, the initial R sei and R ct However, it can be seen that the resistance increase rate after cycling, which is related to the life characteristics, is lower in the positive electrode active materials of Examples 1 to 5 than in Comparative Example 1. In other words, when binary doping containing Nb is applied to NCMA, the R sei and R ct It can be confirmed that the resistance increase rate is effectively suppressed.

[0203] In particular, as shown in Table 6, in the case of the positive electrode active materials prepared in Examples 3 to 5, the resistance increase rates of Rsei and Rct are significantly improved.

[0204] Therefore, when the measurement results of the diffusion coefficient and impedance are taken into consideration, the appropriate Nb doping amount in this embodiment is in the range of 0.00005 mol to 0.03 mol, specifically 0.0001 mol to 0.01 mol or 0.0005 mol to 0.0025 mol, relative to 100 mol of nickel, cobalt, manganese, and doping elements.

[0205] Furthermore, looking at the resistance characteristics shown in Table 8, when the Nb doping amount is 0.0005 mol to 0.0025 mol, it can be seen that the initial Rsei and Rct values ​​increase slightly compared to Comparative Example 1. However, it can be seen that after cycling, the increase in Rct and Rsei values ​​is significantly reduced compared to Comparative Example 1. In other words, when Nb is doped into the cathode material, the surface properties are improved and side reactions between the electrolyte and the cathode are suppressed, which confirms that the increase in resistance after high-temperature cycling is not significant.

[0206] In addition, in the initial resistance characteristics shown in Table 2, the initial resistance itself decreases when Nb is added, which confirms that Nb effectively contributes to Li migration at high voltages based on the initial voltage characteristics measured at high voltages. Looking at the results of the resistance characteristics, it can be seen that appropriate Nb doping can improve the initial output and suppress degradation.

[0207] The present invention is not limited to the above-described embodiments, and can be manufactured in various different forms, and a person skilled in the art to which the present invention pertains should understand that the present invention can be embodied in other specific forms without changing the technical concept or essential characteristics of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting.

Claims

1. Metal oxide particles including nickel, cobalt, manganese, and aluminum; and Two doping elements doped into the metal oxide particles Including, the two doping elements are Nb and Zr; the doping amount of Nb is 0.0001 mole to 0.0025 mole per mole of the total of nickel, cobalt, manganese, aluminum and the doping element; the doping amount of Zr is 0.002 to 0.005 moles per mole of the total of nickel, cobalt, manganese, aluminum and the doping element; the content of aluminum is in the range of 0.01 mol to 0.025 mol per 1 mol of the total of nickel, cobalt, manganese and aluminum, The positive electrode active material for a lithium secondary battery, wherein the content of the nickel is 83 mol % or more based on 1 mol of the total of the nickel, cobalt, manganese, and aluminum.

2. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the doping amounts of Nb and Zr satisfy the relationship of the following formula 1: [Formula 1] 0.3<[Zr] / [Nb]<40 (In formula 1, [Nb] and [Zr] represent the doping amounts of each element based on 1 mole of the total of nickel, cobalt, manganese, aluminum, and the doping element.)

3. The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the positive electrode active material is represented by the following Chemical Formula 1: [Chemical formula 1] Li ａ [Ni ｘ Yes ｙ M ｚ Al ｈ ] １－ｔ (Nb) ｉ Zr ｊ )O2(1-p)X2p (In the above Chemical Formula 1, X is one or more elements selected from the group consisting of F, N, and P; a is 0.8≦a≦1.3, t = i + j is satisfied, and t satisfies 0.0011≦t≦0.007; 0.83≦x≦0.92, 0<y≦0.2, 0<z≦0.2, 0.01≦h≦0.025, 0.0001≦i≦0.0025, 0.002≦j≦0.005, 0≦p≦0.02)

4. The initial diffusion coefficient of the positive electrode active material is 7.30*10 －９ m ２ / sec~8.10*10 －９ m ２ The positive electrode active material for a lithium secondary battery according to claim 1 , wherein the capacitance is in the range of 1 / sec.

5. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the metal oxide particles have a crystal grain size ranging from 900 Å to 1,550 Å.

6. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the full width at half maximum (FWHM) value for the (110) plane of the metal oxide particles is in the range of 0.1890 to 0.2200.

7. The positive electrode active material for a lithium secondary battery has, when measured with an X-ray diffraction pattern, 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein I(003) / I(104), which is the peak intensity ratio of the (003) plane to the peak intensity of the (104) plane, is in the range of 1.2300 to 1.2410.

8. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 7; a negative electrode; and non-aqueous electrolyte A lithium secondary battery comprising:

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