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 including the same. According to one embodiment, a positive electrode active material for a lithium secondary battery is provided, the positive electrode active material including metal oxide particles including nickel, cobalt, manganese, and aluminum, and three 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, driven by the explosive increase in demand for electric vehicles and the need for increased driving distances, the development of secondary batteries having high capacity and high energy density that can be applied to such vehicles has been actively pursued 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-based positive electrode active materials with a high nickel content eventually exhibit problems such as 1) a decrease in efficiency due to a decrease in capacity, 2) the formation of a NiO rock salt structure due to oxygen generation on the surface, which leads to a decrease in cycle characteristics, and 3) an increase in resistance, as the nickel content increases.

[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 with a high nickel content. Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a positive electrode active material and a lithium secondary battery including the same, which can significantly improve the electrochemical characteristics while solving the problem of performance degradation that occurs in positive electrode active materials with a high nickel content, by doping metal oxide particles containing nickel, cobalt, manganese, and aluminum with three elements. [Means for solving the problem]

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

[0008] The three doping elements can be Nb, B and Zr.

[0009] The doping amount of Nb may be in the range of 0.00001 mol to 0.03 mol per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0010] The doping amount of B may be in the range of 0.001 mol to 0.02 mol per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0011] The doping amount of Zr may be in the range of 0.001 mol to 0.007 mol per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0012] The doping amounts of Nb and Zr can satisfy the relationship of the following formula 1.

[0013] [Formula 1] 0.5<[Zr] / [Nb]<10 (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 doping amounts of Nb and B can satisfy the relationship of the following formula 2.

[0014] [Formula 2] 0.3<[B] / [Nb]<30 (In formula 1, [Nb] and [B] represent the doping amounts of each element based on 1 mole of the total of nickel, cobalt, manganese, aluminum, and the doping element.)

[0015] The positive electrode active material may be represented by the following Chemical Formula 1: [Chemical formula 1] Li a [Ni x Co y Mn z Al h ] 1-t (Nb i Zr j B k ) 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 0.0061≦t≦0.057, 0.6≦x≦0.95, 0 <y≦0.2、0<z≦0.2、0.008≦h≦0.029、0.0001≦i≦0.03、0.001≦j≦0.007,0.005)≦k≦0.02、0≦p≦0.02である。

[0016] In this embodiment, the h may be in the range of 0.005≦h≦0.025.

[0017] 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.

[0018] The crystal grain size of the metal oxide particles may be in the range of 1,000 Å to 1,560 Å.

[0019] The full width at half maximum (FWHM) value of the (110) plane of the metal oxide particles may be in the range of 0.1901 to 0.2017.

[0020] 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 the peak intensity ratio of the (003) plane to the peak intensity of the (104) plane, may be in the range of 1.2350 to 1.2410.

[0021] The content of nickel in the metal oxide particles may be 0.8 moles or more based on 1 mole of the total of the nickel, cobalt, manganese, and aluminum.

[0022] 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]

[0023] The positive electrode active material according to the present disclosure is obtained by doping metal oxide particles containing NCMA with at least two elements, and when applied to a lithium secondary battery, it can significantly improve the room temperature and high temperature life characteristics, initial efficiency, initial resistance, resistance increase rate, and thermal stability while increasing the capacity. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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.

[0025] 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 forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. As used in the specification, the term "comprising" means to embody 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.

[0026] When an element is referred to as being "on" or "above" another element, this may be directly on or above the other element, or with other elements in between. In contrast, when an element is referred to as being "directly on" another element, there are no other elements in between.

[0027] 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 this invention pertains. Terms defined in commonly used dictionaries are further analyzed to have meanings that fit the relevant technical literature and the presently disclosed content, and are not interpreted as having ideal or overly formal meanings unless otherwise defined.

[0028] A positive electrode active material for a lithium secondary battery according to one embodiment may include metal oxide particles containing nickel, cobalt, manganese, and aluminum, and two doping elements doped into the metal oxide particles.

[0029] In this case, the three doping elements can be Nb, Zr and B.

[0030] In order to dope lithium metal oxides and ensure their longevity and various electrochemical performances, it is important to select the doping element. Doping elements known 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+ As such, the effects on battery life and output characteristics vary depending on the element.

[0031] In this embodiment, by including Zr, Nb, and B among these doping elements, it is possible to improve the room temperature and high temperature life characteristics and thermal stability while ensuring high capacity, and to significantly reduce the initial resistance characteristics and the resistance increase rate.

[0032] Specifically, Zr 4+ In the case of ZnSe, Zr ions occupy the Li site, acting as a kind of pillar, mitigating the contraction of the lithium ion path during the charge and discharge process and stabilizing the layered structure. This phenomenon reduces cation mixing, increases the lithium diffusion coefficient, and can extend the cycle life.

[0033] Nb can also improve the initial capacity and efficiency.

[0034] When doped with boron (B) along with the doping element, the size of the crystal grains can be reduced during firing of the positive electrode active material, thereby reducing the initial resistance, and also increasing the lifespan characteristics and thermal decomposition temperature.

[0035] In this embodiment, the Nb doping amount may be 0.00001 mol to 0.03 mol, more specifically, 0.0001 mol to 0.01 mol, 0.00005 mol to 0.03 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 the above range, it is possible to achieve very advantageous effects in that the room-temperature life, high-temperature life, resistance increase rate, 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.

[0036] The doping amount of B may be in the range of 0.001 mol to 0.02 mol, more specifically 0.005 mol to 0.02 mol, and even more specifically 0.005 mol to 0.015 mol, per 1 mol of the total of nickel, cobalt, manganese, aluminum, and the doping element. When the doping amount of B satisfies this range, the size of the crystal grains during firing of the positive electrode active material is reduced, thereby reducing the initial resistance value and increasing the room temperature and high temperature life characteristics and thermal decomposition temperature.

[0037] The doping amount of Zr can be 0.001 mol to 0.007 mol, more specifically 0.002 mol to 0.005 mol or 0.0035 mol 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 the above range, the high-temperature life and room-temperature life characteristics of the lithium secondary battery can be significantly improved.

[0038] In this embodiment, the doping amounts of Nb and Zr satisfy the relationship of the following formula 1.

[0039] [Formula 1] 0.3≦[Zr] / [Nb]≦10

[0040] 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.

[0041] More specifically, Equation 1 can be in the range of 0.6 or more and 9 or less, or in the range of 0.7 or more and 7 or less.

[0042] When Formula 1 satisfies the above range, the resistance increase rate is improved and excellent cycle characteristics are obtained.

[0043] On the other hand, the doping amounts of Nb and B satisfy the relationship of the following formula 2.

[0044] [Formula 2] 0.1≦[B] / [Nb]≦30

[0045] In formula 2, [Nb] and [B] represent the doping amounts of each element based on 1 mole of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0046] More specifically, Equation 2 may be in the range of 0.2 or more and 25 or less, or may be in the range of 0.4 or more and 20 or less.

[0047] When Formula 2 satisfies the above range, the stability is improved, the DSC temperature is increased, and the cycle characteristics are improved.

[0048] The positive electrode active material for a lithium secondary battery in this embodiment is represented by the following chemical formula 1.

[0049] [Chemical formula 1] Li a [Ni x Co y Mn z Al h ] 1-t (Nb i Zr j B k ) t O 2-p X2 p

[0050] 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 0.0061≦t≦0.057, 0.6≦x≦0.95, 0 <y≦0.2、0<z≦0.2、0.008≦h≦0.029、0.0001≦i≦0.03、0.001≦j≦0.007,0.005)≦k≦0.02、0≦p≦0.02である。

[0051] In this embodiment, the range of the Al content h may be 0.008 to 0.029, and more specifically, 0.005≦h≦0.025. 3+This prevents Al ions from migrating to tetragonal lattice sites, which would otherwise cause the layered structure to deteriorate into a spinel structure. A layered structure allows for easy insertion and removal of Li ions, while a spinel structure does not allow for smooth Li ion migration. Therefore, when the Al content of the positive electrode active material of this embodiment satisfies the above range, a lithium secondary battery with excellent initial efficiency and thermal stability and significantly improved room-temperature and high-temperature lifespans can be achieved.

[0052] 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.

[0053] In the present embodiment, 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, a positive electrode active material with high output characteristics can be realized. The positive electrode active material of the present 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 suitable for use in electric vehicles.

[0054] 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 8.01*10 -9 m 2 / sec~8.06*10 -9 m 2 / sec range, 8.01*10 -9 m 2 / sec~8.04*10 -9 m 2 / sec, or 8.01*10 -9 m 2 / sec~8.03*10 -9 m 2 / sec range. The initial diffusion coefficient is 8.01*10 -9m 2 / sec~8.06*10 -9 m 2 / sec, the migration of Li ions within the cathode material is effective, which increases the initial capacity and rate-limiting characteristics of the cathode material. On the other hand, the diffusion coefficient is 7.30*10 -9 m 2 If the diffusion coefficient is less than 8.10*10 / sec, the resistance in the cathode material increases, which significantly reduces the cycle characteristics. -9 m 2 If the rate exceeds 1 / sec, the structure becomes unstable and the cycle characteristics deteriorate.

[0055] Next, the crystal grain size of the metal oxide particles may be in the range of 1,000 Å to 1,560 Å, more specifically, in the range of 1,090 Å to 1,350 Å or 1,180 Å to 1,350 Å. When the crystal grain size is in this range, the high-temperature life is improved without reducing the initial capacity.

[0056] The full width at half maximum (FWHM) value of the (110) plane of the metal oxide particles may be in the range of 0.1900 to 0.2030, more specifically 0.1901 to 0.2017, or 0.1901 to 0.2014. When the full width at half maximum (FWHM) value of the (110) plane satisfies the above range, the high-temperature life is significantly improved.

[0057] When measuring the X-ray diffraction pattern of the positive electrode active material of this embodiment, 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 1.2350 to 1.2410, more specifically, in the range of 1.2351 to 1.2407.

[0058] Generally, a peak intensity value means a peak height value or an integrated area value obtained by integrating the area of ​​a peak, and in this embodiment, the peak intensity value means a peak area value.

[0059] When the peak intensity ratio I(003) / I(104) is within the above range, the capacity does not decrease and the structural stabilization is promoted, thereby improving the thermal stability of the positive electrode active material.

[0060] In addition, the peak intensity ratio I(003) / I(104) is a cation mixing index, and if the I(003) / I(104) value decreases, the initial capacity and rate-limiting characteristics of the positive electrode active material may decrease. However, in this embodiment, since the I(003) / I(104) ratio satisfies the above range, a positive electrode active material with excellent capacity and rate-limiting characteristics can be realized.

[0061] 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 assembled from 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 %. Such a bimodal particle distribution can improve energy density.

[0062] 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.

[0063] The description of the positive electrode active material is omitted because it is the same as that of the embodiment of the present invention described above.

[0064] The positive electrode active material layer may include a binder and a conductive material.

[0065] The binder serves to firmly adhere the positive electrode active material particles to each other and to firmly adhere the positive electrode active material to the current collector.

[0066] The conductive material is used to impart conductivity to the electrode, and in the battery being configured, any material can be used as long as it is an electron conductive material and does not cause a chemical change.

[0067] 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.

[0068] Examples of the negative electrode active material include substances that can reversibly intercalate / deintercalate lithium ions, lithium metal, alloys of lithium metal, substances that can dope and undope lithium, or transition metal oxides.

[0069] As the substance that can reversibly intercalate / deintercalate lithium ions, as a carbon material, any carbon-based negative electrode active material generally used in a lithium ion secondary battery can be used, and typical examples thereof include crystalline carbon, amorphous carbon, or both can be used.

[0070] As the alloy of lithium metal, an alloy of lithium and a metal 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 can be used.

[0071] Examples of the substance that can dope and undope lithium include Si, SiO x (0 < x < 2), Si-Y alloy (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), and the like.

[0072] 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.

[0073] The binder serves to firmly adhere the negative active material particles to each other and to firmly adhere the negative active material to the current collector.

[0074] The conductive material is used to impart electrical conductivity to the electrodes, and any material can be used as long as it does not cause a chemical change in the constructed battery and is electron conductive.

[0075] 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.

[0076] The negative and positive electrodes are prepared 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 preparation method is widely known in the art, a detailed description thereof will be omitted here. Examples of the solvent include, but are not limited to, N-methylpyrrolidone.

[0077] The electrolyte includes a non-aqueous organic solvent and a lithium salt.

[0078] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can migrate.

[0079] The lithium salt dissolves in an organic solvent and acts as a lithium ion source in the battery, enabling basic operation of the lithium secondary battery and facilitating lithium ion migration between the positive electrode and the negative electrode.

[0080] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Such separators can be made of polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more of these materials, including 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.

[0081] 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, and into cylindrical, prismatic, coin, pouch, etc. types depending on the shape, and into bulk and thin film types depending on the size. The structure and manufacturing methods of these batteries are widely known in the art, so detailed description will be omitted. [Example]

[0082] The following detailed description of the present invention is provided by way of example only, and the present invention is not limited thereto, but is defined only by the scope of the claims set forth below.

[0083] Preparation Example 1 - Preparation of NCM precursor The positive electrode active material precursor was prepared by a common coprecipitation method. 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 aqueous solutions of metal salts. After preparing the coprecipitation reactor, N2 was purged to prevent oxidation of metal ions during the coprecipitation reaction, and the temperature of the reactor was maintained at 50°C. NH4(OH) was added as a chelating agent to the co-precipitation reactor, 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. 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.

[0084] Example 1 - 0.0035 mol Zr + 0.0025 mol Nb + 0.001 mol B doping The precursor prepared in Preparation Example 1, the lithium raw material, the aluminum raw material, and the doping raw material 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 maintaining the temperature at 740 to 780°C for 15 hours, with a temperature rise rate of 5°C / min. 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), H3BO3 (Aldrich, 3N), and Nb2O5 (Aldrich, 3N). 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. That is, Li(M) 1-x (D) x The overall composition of the large particle size and small particle size positive electrode active materials doped with these two elements is Li(M) 0.993 Zr 0.0035 Nb 0.0025 B 0.001 It was O2. 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.

[0085] 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. 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.

[0086] Example 2 - 0.0035 mol Zr + 0.0025 mol Nb + 0.005 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 2 was Li(M) 0.989 Zr 0.0035 Nb 0.0025 B 0.005 It was O2.

[0087] Example 3 - 0.0035 mol Zr + 0.0025 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 3 was Li(M) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was O2.

[0088] Example 4 - 0.0035 mol Zr + 0.0025 mol Nb + 0.015 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 4 was Li(M) 0.979 Zr 0.0035 Nb0.0025 B 0.015 It was O2.

[0089] Reference Example 1 - 0.0035 mol Zr + 0.0025 mol Nb + 0.02 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 5 was Li(M) 0.974 Zr 0.0035 Nb 0.0025 B 0.02 It was O2.

[0090] Example 5 - 0.002 mol Zr + 0.0025 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 5 was Li(M) 0.9855 Zr 0.002 Nb 0.0025 B 0.01 It was O2.

[0091] Example 6 - 0.005 mol Zr + 0.0025 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 6 was Li(M) 0.9825 Zr 0.005 Nb 0.0025 B 0.01 It was O2.

[0092] Reference Example 2 - 0.008 mol Zr + 0.0025 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Reference Example 2 was Li(M) 0.9795 Zr 0.008 Nb 0.0025 B 0.01 It was O2.

[0093] Example 7 - 0.0035 mol Zr + 0.0025 mol Nb + 0.01 mol B doping + 0.005 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amounts of aluminum raw material and dopant raw material were adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 7 was Li(Ni 0.915 Co 0.04 Mn 0.04 Al 0.005 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0094] Example 8 - 0.0035 mol Zr + 0.0025 mol Nb + 0.01 mol B 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 the dopant was adjusted using the precursor prepared in Preparation Example 1. 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 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0095] Example 9 - 0.0035 mol Zr + 0.0025 mol Nb + 0.01 mol B doping + 0.015 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amounts of aluminum raw material and dopant raw material were adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 11 was Li(Ni 0.905 Co 0.04 Mn 0.04 Al 0.015 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0096] Example 12 - 0.0035 mol Zr + 0.0025 mol Nb + 0.01 mol B doping + 0.022 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amounts of aluminum raw material and dopant raw material were adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 12 was Li(Ni 0.898 Co 0.04 Mn 0.04 Al 0.022 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0097] Reference Example 3 - 0.0035 mol Zr + 0.0025 mol Nb + 0.01 mol B doping + 0.025 mol Al A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amounts of aluminum raw material and dopant raw material were adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Reference Example 3 was Li(Ni 0.895 Co 0.04 Mn 0.04 Al 0.025 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0098] Example 11 - 0.0035 mol Zr + 0.0005 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 11 was Li(M) 0.986 Zr 0.0035 Nb 0.0005 B 0.01 It was O2.

[0099] Example 12 - 0.0035 mol Zr + 0.001 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Example 12 was Li(M) 0.9855 Zr 0.0035 Nb 0.0001 B 0.01 It was O2.

[0100] Reference Example 4 - 0.0035 mol Zr + 0.005 mol Nb + 0.01 mol B doping A bimodal cathode active material was prepared in the same manner as in Example 1, except that the amount of the dopant was adjusted using the precursor prepared in Preparation Example 1. The overall composition of the positive electrode active material prepared in Reference Example 4 was Li(M) 0.9815 Zr 0.0035 Nb 0.005 B 0.01 It was O2. The doping amounts and overall compositions of the positive electrode active materials prepared in Comparative Example 1, Examples 1 to 12, and Reference Examples 1 to 4 are as shown in the table below.

[0101] [Table 1]

[0102] Comparative Example 2 - 0.78 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doped + 0.02 mol Al In the same manner as in Production Example 1, 0.80 Co 0.10 Mn 0.10 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amounts of aluminum raw material and dopant raw material were adjusted. 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 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0103] Comparative Example 3 - 0.81 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doped + 0.02 mol Al In the same manner as in Production Example 1, 0.83 Co 0.12 Mn 0.05 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amount of the doping material was adjusted. 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 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0104] Comparative Example 4 - 0.83 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doped + 0.02 mol Al In the same manner as in Production Example 1, 0.85 Co 0.07 Mn 0.08Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amount of the doping material was adjusted. The overall composition of the positive electrode active material prepared in Comparative Example 4 was Li(Ni 0.83 Co 0.07 Mn 0.08 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0105] Comparative Example 5 - 0.84 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doped + 0.02 mol Al In the same manner as in Production Example 1, 0.86 Co 0.07 Mn 0.07 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amount of the doping material was adjusted. 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 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0106] Comparative Example 6 - 0.86 mol Ni + 0.0035 mol Zr + 0.0025 mol Nb doped + 0.02 mol Al In the same manner as in Production Example 1, 0.88 Co 0.05 Mn 0.07 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared using the precursor in the same manner as in Example 1, except that the amount of the doping material was adjusted. The overall composition of the positive electrode active material prepared in Comparative Example 6 was Li(Ni0.86 Co 0.05 Mn 0.07 Al 0.02 ) 0.994 Zr 0.0035 Nb 0.0025 It was.

[0107] Reference Example 5 - In Example 1, only Ni was changed to 0.78 mol In the same manner as in Production Example 1, 0.80 Co 0.10 Mn 0.10 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor was used. The overall composition of the positive electrode active material prepared in Reference Example 5 was Li(Ni 0.78 Co 0.01 Mn 0.01 Al 0.02 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0108] Reference Example 6 - In Example 1, only Ni was changed to 0.81 mol In the same manner as in Production Example 1, 0.83 Co 0.12 Mn 0.05 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor was used. The overall composition of the positive electrode active material prepared in Reference Example 6 was Li(Ni 0.81 Co 0.12 Mn 0.05 Al 0.02 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0109] Example 13 - In Example 1, only Ni was changed to 0.83 mol In the same manner as in Production Example 1, 0.85 Co0.07 Mn 0.08 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor was used. The overall composition of the positive electrode active material prepared in Example 13 was Li(Ni 0.83 Co 0.07 Mn 0.08 Al 0.02 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0110] Example 14 - In Example 1, only Ni was changed to 0.84 mol In the same manner as in Production Example 1, 0.86 Co 0.07 Mn 0.07 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor was used. The overall composition of the positive electrode active material prepared in Example 14 was Li(Ni 0.84 Co 0.07 Mn 0.07 Al 0.02 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was.

[0111] Example 15 - In Example 1, only Ni was changed to 0.86 mol In the same manner as in Production Example 1, 0.88 Co 0.05 Mn 0.07 Large and small particle size precursors with the composition )(OH)2 were prepared. Next, a bimodal cathode active material was prepared in the same manner as in Example 1, except that the precursor was used. The overall composition of the positive electrode active material prepared in Example 15 was Li(Ni 0.86 Co 0.05 Mn 0.07 Al0.02 ) 0.984 Zr 0.0035 Nb 0.0025 B 0.01 It was. The doping amounts and overall compositions of the Comparative Examples 2 to 6, Reference Examples 5 to 6, and Examples 13 to 15 are as shown in the table below.

[0112] [Table 2]

[0113] Experimental Example 1 - XRD analysis results The lattice constants of the positive electrode active materials produced in Examples 1 to 4, Reference Example 1, and Comparative Example 1 were obtained by X-ray diffraction measurement using CuKα radiation. The measured lengths of the a-axis, b-axis, and c-axis are shown in Table 3 below. The unit cell volume and crystalline size of the active material were measured and are shown in Table 3 below.

[0114] Next, Rietveld analysis was performed using the commercial software High Score Plus 4.0 program for crystallographic consideration of the 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 Rietveld refinement. The Goodness of Fitness (GOF) values ​​matched within 2.0.

[0115] The intensity (peak area) 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 the full width at half maximum (FWHM) of the (110) plane were calculated and are shown in Table 3.

[0116] Furthermore, it was confirmed that all the measured samples had a well-developed (003) plane as the main peak around 18.7°, with splitting of the (006) / (102) peak between 37.5° and 38.5° and the (108) / (110) peak between 63.5° and 35.5°. This indicates that the samples have a good crystalline ordering of hexagonal layers and exhibit a typical α-NaFeO2 (space group R-3m) structure.

[0117] [Table 3]

[0118] Referring to Table 3, it can be seen that the crystalline structure factor values ​​of the XRD analysis results change depending on the doping element and the doping amount. Specifically, in the case of Reference Example 1, the crystal structure constants a and b are rapidly decreased due to excessive doping with 0.02 moles of B. The rapid decrease in the lattice constant a leads to a contraction of the unit cell volume, which is thought to be due to a partial change in the crystal structure caused by the excessive B doping. That is, it can be confirmed that the doping amount of B can be in the range of 0.005 mol to 0.02 mol, and preferably in the range of 0.001 mol to 0.015 mol.

[0119] Experimental Example 2 - Electrochemical Evaluation (1) Manufacturing of coin-type half cells A CR2032 coin cell was fabricated using the positive electrode active material prepared as described above, and then electrochemical evaluation was performed. 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. 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 / m 2 The rolling density is approximately 3.1 g / cm 3 there were. 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.

[0120] (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 performed. 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. 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.

[0121] (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.

[0122] (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 at a constant current and constant voltage of 2.5V to 4.25V with a 1 / 20C cut-off at 25°C, and measuring the voltage 60 seconds after applying the discharge current at 4.25V (100% charge). The resistance increase rate was calculated by measuring the resistance after 30 cycles of the cycle life in the same manner as the initial resistance measurement method for the resistance initially measured at room temperature (25°C) (room temperature initial resistance), and converting the increase rate into a percentage (%). 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.

[0123] (5) Evaluation of thermal stability For differential scanning calorimetry (DSC), the half-cell was initially charged to 4.25 V at 0.1 C charging conditions, then the half-cell was 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 DSC peak temperature was measured using a Mettler Toledo DSC1 Star system to measure the change in heat quantity.

[0124] Experimental Example 2-1. Effect according to B content The results of evaluation of the electrochemical properties of the positive electrode active materials prepared in Examples 1 to 7 and Comparative Example 1, performed by the method of Experimental Example 2, are shown in Table 4 below.

[0125] [Table 4]

[0126] Examples 1 to 4 show the results of measuring the electrochemical properties according to the doping amounts when an Al raw material was mixed with a precursor having an Ni content of 90 mol % or more and doped with Zr, Nb, and B.

[0127] Referring to Table 4, it can be seen that the positive electrode active materials of Examples 1 to 4, in which NCMA is doped with Zr, Nb, and B, have significantly increased discharge capacity and initial capacity compared to the positive electrode active material of Comparative Example 1, in which NCMA is doped with Zr.

[0128] Furthermore, when Nb and B are doped together with Zr as in Examples 1 to 4, the discharge capacity remains similar, and the room temperature and high temperature lifespans are significantly increased. Furthermore, the resistance increase rate, average leakage current, and DSC peak temperature are all improved. This is believed to be because B remains on the surface of the positive electrode active material, simultaneously providing a lithium ion conductor coating effect.

[0129] This shows that the problem of rapid decrease in discharge capacity and initial efficiency, which occurs in conventional positive electrode active materials doped with Al and Zr by adding 0.01 mole or more of Al, is significantly improved.

[0130] However, when excessive B is doped as in Reference Example 1, it is found that the discharge capacity and initial efficiency are significantly reduced. Taking this into consideration, as described above, it can be confirmed that the doping amount of B can be in the range of 0.001 mol to 0.02 mol, and preferably in the range of 0.005 mol to 0.015 mol, per 1 mol of the total of nickel, cobalt, manganese, aluminum, and the doping element.

[0131] Experimental Example 2-2. Effect according to Zr content The electrochemical properties of the positive electrode active materials prepared in Examples 5 and 6 and Reference Example 2 were evaluated by the method of Experimental Example 2 and the results are shown in Table 5. For comparison, the results of Example 3 are also shown.

[0132] [Table 5]

[0133] In Examples 5 and 6 and Reference Example 2, the amount of Nb doped into NCMA doped with 0.2 mol of aluminum was fixed at 0.0025 mol and the amount of B doped was fixed at 0.01 mol, and only the amount of Zr doped was changed.

[0134] Referring to Table 5, it can be seen that as the doping amount of Zr increases from 0.002 moles to 0.008 moles, some properties improve and some properties deteriorate.

[0135] Specifically, the results of Examples 3, 5, and 6 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 1, the discharge capacity and initial efficiency are significantly reduced.

[0136] Therefore, the appropriate doping amount of Zr in this example is 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 1 mol of the total of nickel, cobalt, manganese and the doping element.

[0137] Experimental Example 2-3. Effect according to Al content The electrochemical properties of the positive electrode active materials prepared in Examples 7 to 10 and Reference Example 3 were evaluated by the method of Experimental Example 2 and the results are shown in Table 6 below. For comparison, the results of Example 3 are also shown.

[0138] [Table 6]

[0139] In Examples 7 to 10 and Reference Example 3, the doping amounts were fixed at Zr 0.0035 mol, Nb 0.0025 mol, and B 0.01 mol, and only the amount of Al raw material was changed.

[0140] Referring to Table 6, it can be seen that as the amount of Al raw material increases, the room temperature life and high temperature life increase significantly, and the room temperature initial resistance, resistance increase rate, and leakage current decrease. In particular, the DSC peak temperature increases significantly.

[0141] However, in the case of Reference Example 3 in which the amount of Al raw material mixed was 0.025 mol, the discharge capacity was significantly reduced, and as a result, the initial efficiency was also significantly reduced.

[0142] Therefore, in this embodiment, the amount of aluminum raw material may be in the range of 0.008 mol to 0.029 mol, more specifically, 0.005 mol to 0.025 mol, per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0143] Experimental Example 2-4. Effect according to Nb content The electrochemical properties of the positive electrode active materials prepared in Examples 11 and 12 and Reference Example 4 were evaluated by the method of Experimental Example 2 and the results are shown in Table 7 below. For comparison, the results of Example 3 are also shown.

[0144] [Table 7]

[0145] In Examples 11 and 12 and Reference Example 4, only the doping amount of Nb was changed while Zr was fixed at 0.0035 mol and B was fixed at 0.01 mol in NCMA into which 0.02 mol had been introduced.

[0146] Referring to Table 7, it can be seen that the discharge capacity and initial efficiency increase significantly as the Nb content increases.

[0147] However, in the case of Reference Example 4 in which Nb was excessively doped at 0.005 mol, it was confirmed that the discharge capacity was greatly reduced and the initial efficiency also dropped sharply.

[0148] Therefore, the appropriate doping amount of Nb in this example 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, per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element.

[0149] Experimental Example 2-5. Effects according to Ni content The results of evaluating the electrochemical properties of the positive electrode active materials prepared in Comparative Examples 2 to 6, Reference Examples 5 and 6, and Examples 13 to 15 using the method of Experimental Example 2 are shown in Table 8 below. For comparison, the results of Comparative Example 1 and Example 3 are also shown.

[0150] [Table 8]

[0151] Comparative Examples 2 to 6 are positive electrode active materials in which NCMA is doped with Zr and Nb, and Reference Examples 5 to 6 and Examples 13 to 15 are positive electrode active materials produced by mixing NCMA with Zr-, Nb-, and B-doped raw materials.

[0152] Referring to Table 8, in Examples 13 to 15 in which B was also used as a doping material, the room temperature life, high temperature life, resistance increase rate, and average leakage current value were all improved.

[0153] In addition, since the DSC peak temperatures all increased, it can be seen that when B is contained as a doping element, the thermal stability of the positive electrode active material can be significantly improved.

[0154] As a result, when a ternary material containing Zr, Nb, and B is doped in an NCMA product having a Ni content of 83% or more as in this example, it can be confirmed that the effects of increasing discharge capacity and initial efficiency are very excellent, and other physical properties are also improved overall.

[0155] Experimental Example 3 - Diffusion Coefficient and Impedance Analysis The positive electrode active materials prepared in Examples 1 to 4, Reference Example 1, and Comparative Example 1 were subjected to diffusion coefficient and impedance analysis, and the results are shown in Table 7 below.

[0156] The diffusion coefficient was measured by the GITT method, and the battery was charged for 30 minutes and then maintained for 50 minutes. The data obtained at this time was analyzed using the following equation 3.

[0157] [Formula 3]

number

[0158] In Equation 3, 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 ×: fraction in which lithium exists 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)

[0159] Specifically, the molar volume of the positive electrode active material was calculated using the unit volume analyzed by the XRD measurement results. A is the area of ​​the electrode when the diffusion coefficient was measured. In the case of the coin cell used for the diffusion coefficient measurement, the area was 1.538 cm. 2 It has a size of I o means a 0.1C current value. X is calculated assuming the entire charge / discharge interval is 100%. For example, the x corresponding to the first 30-minute charge interval can be expressed as 0.05, the x corresponding to the second 30-minute charge interval can be expressed as 0.1, and the x corresponding to the intermediate interval can be expressed as 0.5.

[0160] The impedance analysis was performed using the impedance graph obtained at 3.7 V, and the results are shown in Table 9 below, along with the diffusion coefficient. The impedance values ​​obtained were separated into the real axis and the imaginary axis, and a Nyquist plot was performed. The resulting figure was divided into two semicircular shapes and fitted to obtain the R sei and R ct 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 called R ct The resistance was calculated as follows. Examining the resistance characteristics shown in Table 8, when the doping amount of B was 0.005 mol to 0.015 mol, the initial Rsei and Rct values ​​increased slightly compared to Comparative Example 1, indicating a slight increase in initial resistance. However, after cycling, the increase in Rct and Rsei values ​​decreased compared to Comparative Example 1. In other words, when B is doped into the cathode material, the surface properties are improved and side reactions between the electrolyte and the cathode are suppressed, indicating that the increase in resistance after high-temperature cycling is not significant. In particular, the suppression of the increase in Rsei resistance indicates the suppression of reactions with the electrolyte, and the suppression of the increase in Rct resistance indicates the suppression of electrode activity degradation of the cathode material. It can be seen that the appropriate doping of B can improve the initial output and suppress degradation.

[0161] [Table 9]

[0162] Referring to Table 9, the initial R sei and R ct It can be seen that the initial resistance value of R increases, but the rate of increase in resistance after cycling drops significantly. In particular, the rate of increase in resistance of Rct, which is the core resistance of electron transport, drops significantly. Based on this, it can be seen that when Zr, Nb, and B are doped simultaneously, they have the property of suppressing electrode degradation. In other words, by doping these elements simultaneously, R sei and R ctIt can be seen that the resistance increase rate is effectively suppressed.

[0163] The present invention is not limited to the above-described embodiment, and can be manufactured in various different forms, and a person skilled in the art to which the present invention pertains can understand that the present invention can be embodied in other specific forms without changing the technical idea or essential features of the present invention. Therefore, the above-described embodiment should be understood to be illustrative in all respects and not limiting.

Claims

1. Metal oxide particles including nickel, cobalt, manganese, and aluminum; and Three doping elements doped into the metal oxide particles Including, the three doping elements are Nb, B and Zr; The doping amount of Nb is in the range of 0.0005 mol to 0.0025 mol per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element; the doping amount of B is in the range of 0.001 mol to 0.015 mol per 1 mol of the total of nickel, cobalt, manganese, aluminum and the doping element; the doping amount of Zr is in the range of 0.002 mole to 0.005 mole per mole of the total of nickel, cobalt, manganese, aluminum and the doping element; the content of nickel is in the range of 0.83 mol to 0.95 mol per 1 mol of the total of nickel, cobalt, manganese, and aluminum; The content of the aluminum is in the range of 0.01 mole to 0.022 mole per mole of the total of nickel, cobalt, manganese, and aluminum. Positive electrode active material for lithium secondary batteries.

2. 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] 0.5<[Zr] / [Nb]<10 (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. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the doping amounts of Nb and B satisfy the relationship of the following formula 2: [Formula 2] 0.3<[B] / [Nb]<30 (In formula 1, [Nb] and [B] represent the doping amounts of each element based on 1 mole of the total of nickel, cobalt, manganese, aluminum, and the doping element.)

4. 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 B ｋ )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 + k, where t is 0.0061≦t≦0.057; 0.83≦x≦0.95, 0<y≦0.2, 0<z≦0.2, 0.01≦h≦0.022, 0.0005≦i≦0.0025, 0.002≦j≦0.005, 0.001≦k≦0.015, 0≦p≦0.02.)

5. 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 positive electrode active material has a capacitance of 1 / 2 s. / sec.

6. 2. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the crystal grain size of the metal oxide particles is in the range of 1,000 Å to 1,560 Å.

7. 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 0.1901 to 0.2017.

8. The positive electrode active material for a lithium secondary battery has an X-ray diffraction pattern 2. The positive electrode active material for lithium secondary batteries 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 1.2350 to 1.2410.

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

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