Positive electrode active material, preparation method thereof, positive electrode sheet, battery and electrical equipment

Abstract

The present invention discloses a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery and an electrical device. The positive electrode active material includes a plurality of primary particles, and the equivalent number of sheet layers N of the (003) crystal plane of the positive electrode active material (003) and the equivalent number of sheet layers N of the (104) crystal plane (104) satisfy: N (003) *N (104) is 1×10 4 -3×10 4 , where D (003) is the average thickness of the positive electrode active material microcrystal in the direction perpendicular to the (003) crystal plane, with the unit of nm, and d (003) is the crystal plane spacing of the (003) crystal plane in the positive electrode active material microcrystal, with the unit of nm, D (104) is the average thickness of the positive electrode active material microcrystal in the direction perpendicular to the (104) crystal plane, with the unit of nm, and d (104) is the crystal plane spacing of the (104) crystal plane in the positive electrode active material microcrystal, with the unit of nm. Thus, by using this positive electrode active material, the battery loaded with it can take into account high energy density, cycle performance, rate performance and safety performance.

Description

Technical Field

[0001] The present invention belongs to the field of batteries, and particularly relates to a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery, and an electrical device using the same. Background Art

[0002] With the continuous upgrading of the market demand for electric vehicles, higher requirements are also put forward for the energy density, rate performance, and lifespan of batteries. Since the positive electrode material of a battery has the greatest impact on cost and performance in the power battery system, it has always been one of the main research hotspots in the field of power batteries. Among them, the layered lithium nickel cobalt manganese oxide ternary positive electrode material has a high specific capacity and is currently the mainstream choice in the market of positive electrode materials for power batteries. However, how to enable the battery loaded with the layered ternary positive electrode material to have both high energy density, cycle life, and safety performance is still a highly concerned issue in the research field and application market. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the present invention is to provide a positive electrode active material, a preparation method thereof, a positive electrode sheet, a battery, and an electrical device using the same. By using the positive electrode active material, the battery loaded with it can take into account high energy density, cycle performance, rate performance, and safety performance.

[0004] In one aspect of the present invention, a positive electrode active material is provided. According to an embodiment of the present invention, the positive electrode active material includes a plurality of primary particles, and the number of equivalent sheet layers N of the (003) crystal plane of the positive electrode active material (003) and the number of equivalent sheet layers N of the (104) crystal plane (104) satisfy: N (003) *N (104) is 1×10 4 -3×10 4 , where D (003) is the average thickness of the positive electrode active material microcrystal in the direction perpendicular to the (003) crystal plane, with the unit of nm, d (003) is the crystal plane spacing of the (003) crystal plane in the positive electrode active material microcrystal, with the unit of nm, D (104) is the average thickness of the positive electrode active material microcrystal in the direction perpendicular to the (104) crystal plane, with the unit of nm, d (104) is the crystal plane spacing of the (104) crystal plane in the positive electrode active material microcrystal, with the unit of nm.

[0005] For the positive electrode active material according to an embodiment of the present invention, the number of equivalent sheet layers N of the (003) crystal plane (003) and the number of equivalent sheet layers N of the (104) crystal plane (104) satisfy: N (003) *N (104) is 1×104 -3 * 10 4 , so that the positive electrode active material has ultra-high capacity and rate performance, and during long-term cycling, the microcrystalline body of the positive electrode active material has sufficient elasticity for expansion and contraction, improving the particle strength and charge-discharge cycle life of the material. Thus, using the positive electrode active material of the present invention can enable the battery loaded with it to have both high energy density, cycle performance, rate performance, and safety performance.

[0006] In addition, the positive electrode active material according to the above embodiments of the present invention may further have the following additional technical features:

[0007] In some embodiments of the present invention, N (003) *N (104) is 1.5 * 10 4 -2.5 * 10 4 . Thus, the energy density, cycle performance, rate performance, and safety performance of the battery can be further improved.

[0008] In some embodiments of the present invention, the equivalent number of sheet layers N of the (003) crystal plane of the positive electrode active material (003) (003) is 80 - 140, preferably 90 - 130.

[0009] In some embodiments of the present invention, the equivalent number of sheet layers N of the (104) crystal plane of the positive electrode active material (104) (104) is 130 - 200, preferably 140 - 190.

[0010] In some embodiments of the present invention, where K is the Scherrer constant 0.89, λ is the wavelength of the test X-ray, β1 is the full width at half maximum of the diffraction peak of the (003) crystal plane in the microcrystal of the positive electrode active material, and θ1 is the Bragg diffraction angle of the (003) crystal plane in the microcrystal of the positive electrode active material.

[0011] In some embodiments of the present invention,

[0012] In some embodiments of the present invention, the average thickness D perpendicular to the (003) crystal plane direction in the microcrystal of the positive electrode active material (003) is 40 nm - 60 nm, preferably 45 nm - 55 nm.

[0013] In some embodiments of the present invention, the interplanar spacing d of the (003) crystal plane of the positive electrode active material (003) is 0.4730 nm - 0.4760 nm, preferably 0.4732 nm - 0.4750 nm.

[0014] In some embodiments of the present invention, Wherein K is the Scherrer constant 0.89, λ is the wavelength of the X-ray for testing, β2 is the full width at half maximum of the diffraction peak of the (104) crystal plane in the microcrystals of the positive electrode active material, and θ2 is the Bragg diffraction angle of the (104) crystal plane in the microcrystals of the positive electrode active material.

[0015] In some embodiments of the present invention,

[0016] In some embodiments of the present invention, the average thickness D in the direction perpendicular to the (104) crystal plane in the microcrystals of the positive electrode active material (104) is 20 nm - 50 nm, preferably 30 nm - 40 nm.

[0017] In some embodiments of the present invention, the interplanar spacing d of the (104) crystal plane of the positive electrode active material (104) is 0.2035 nm - 0.2045 nm, preferably 0.2037 nm - 0.2042 nm.

[0018] In some embodiments of the present invention, the positive electrode active material includes a matrix, and the matrix includes Li 1+ a Ni x Co y Mn z M m O2, -0.05 ≤ a ≤ 0.3, 0.8 ≤ x ≤ 1, 0 ≤ y ≤ 0.2, 0 ≤ z ≤ 0.2, 0.002 ≤ m ≤ 0.01, and M includes at least one of Sb, Nb, Mg, La, Ti, Al, Sr, Ba, Y, Zr, Ca, Fe, S, Zn, and Ta. Thereby, the energy density, cycle performance, rate performance, and safety performance of the battery can be further improved.

[0019] In some embodiments of the present invention, the positive electrode active material further includes a coating layer, the coating layer is formed on at least a part of the surface of the matrix, and the coating layer contains element J, and element J includes at least one of F, B, Cl, Br, I, S, Al, W, Co, Sn, and Mo. Thereby, the energy density, cycle performance, rate performance, and safety performance of the battery can be further improved.

[0020] In the second aspect of the present invention, the present invention provides a method for preparing the above positive electrode active material, including:

[0021] Providing a positive electrode active material precursor;

[0022] Performing a first mixed sintering on the positive electrode active material precursor, a lithium source, and a dopant containing element M to obtain a first sintered material of the positive electrode active material.

[0023] Thus, the above-mentioned positive electrode active material can be prepared by adopting this method, so that the battery loaded with the positive electrode active material takes into account high energy density, cycle performance, rate performance and safety performance.

[0024] In some embodiments of the present invention, the positive electrode active material precursor is prepared by the following method: adjusting a mixed system including nickel salt, cobalt salt, manganese salt, precipitating agent and complexing agent to pH1, and the pH1 value is 9-12 to obtain precursor crystal nuclei; the Dv50 of the precursor crystal nuclei is 2μm-4μm, and adjusting the mixed system to pH2, and the pH2 value is 9-13 to obtain a positive electrode active material precursor, wherein the pH2 value is greater than the pH1 value.

[0025] In some embodiments of the present invention, the difference between the pH2 value and the pH1 value is 0.1-1.

[0026] In some embodiments of the present invention, the positive electrode active material precursor satisfies at least one of the following conditions:

[0027] The Dv50 of the positive electrode active material precursor is 9μm-20μm;

[0028] The equivalent number of lamellae N of the (101) crystal plane of the positive electrode active material precursor (101) is 60-120, preferably 60-90;

[0029] The equivalent number of lamellae N of the (001) crystal plane of the positive electrode active material precursor (001) is 20-60, preferably 20-50;

[0030] The equivalent number of lamellae N of the (100) crystal plane of the positive electrode active material precursor (100) is 110-140, preferably 110-130.

[0031] Thus, the capacity and rate performance of the positive electrode active material can be improved.

[0032] In some embodiments of the present invention, the temperature of the first mixed sintering is 650°C-900°C, and the time is 4h-15h.

[0033] In some embodiments of the present invention, the method further includes second mixed sintering of the positive electrode active material first sintered material and a coating agent containing element J to form a coating layer containing element J on at least part of the surface of the positive electrode active material first sintered material. Thus, the cycle stability of the positive electrode active material can be improved.

[0034] In some embodiments of the present invention, the temperature of the second mixed sintering is 200°C-700°C, and the time is 3h-10h.

[0035] In the third aspect of the present invention, a positive electrode sheet is provided, which includes the positive electrode active material described in the first aspect of the present invention or the positive electrode active material obtained by the method described in the second aspect of the present invention. Thereby, the battery loaded with it takes into account high energy density, cycling performance, rate performance and safety performance.

[0036] In the fourth aspect of the present invention, a battery is provided, which includes the positive electrode sheet described in the third aspect of the present invention. Thereby, the battery takes into account high energy density, cycling performance, rate performance and safety performance.

[0037] In the fifth aspect of the present invention, an electrical device is provided, which includes the battery described in the fourth aspect of the present invention.

[0038] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. Detailed Embodiments

[0039] The embodiments of the present invention will be described in detail below, which are intended to explain the present invention and should not be construed as a limitation to the present invention.

[0040] The endpoints and any values disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0041] In one aspect of the present invention, a positive electrode active material is provided. According to an embodiment of the present invention, the positive electrode active material includes a plurality of primary particles, and the number of equivalent sheet layers N of the (003) crystal plane of the positive electrode active material (003) (003) and the number of equivalent sheet layers N of the (104) crystal plane (104) satisfy: N (003) *N (104) is 1×10 4 -3×10 4 , where D (003) is the average thickness perpendicular to the (003) crystal plane direction in the microcrystals of the positive electrode active material, with the unit of nm, and d (003) is the (003) crystal plane spacing in the microcrystals of the positive electrode active material, with the unit of nm, D (104) is the average thickness perpendicular to the (104) crystal plane direction in the microcrystals of the positive electrode active material, with the unit of nm, and d (104) is the (104) crystal plane spacing in the microcrystals of the positive electrode active material, with the unit of nm.

[0042] The inventors found that the number of equivalent sheet layers of the crystal plane of the layered cathode active material represents the framework size of the R-3m structure. For the layered cathode active material, the statistically stacked number of layers in a certain direction can reflect the average number of lattice sites in that direction. For the layered cathode active material, the number of equivalent sheet layers of the crystal plane in each direction can truly reflect the number of active lithium sites that a single microcrystal can accommodate, which will affect the capacity, lithium ion transport channels, and overall structural stability. The number of equivalent sheet layers N of the (003) crystal plane of the cathode active material (003 ) and the number of equivalent sheet layers N of the (104) crystal plane (104) The product (N (003) *N (104) ) reflects the product of the number of equivalent sheet layers of the crystal plane in the c-axis direction and the a-axis direction of the unit cell, representing the stacking degree of the overall layered framework of the microcrystal, and determining the total number of lithium sites that the cathode active material can accommodate from the structure-activity relationship, which not only affects the total capacity of the material but also determines the stability of the crystal. The inventors further found that the number of equivalent sheet layers N of the (003) crystal plane of the cathode active material (003) and the number of equivalent sheet layers N of the (104) crystal plane (104) satisfy: N (003) *N (104) is 1×10 4 -3×10 4 , which can enable the cathode active material to have ultra-high capacity and rate performance, and during long cycling, the microcrystal body of the cathode active material has sufficient expansion and contraction elasticity, improving the particle strength and charge-discharge cycle life of the material. Thus, using the cathode active material of the present invention can enable the battery loaded with it to take into account high energy density, cycle performance, rate performance, and safety performance.

[0043] According to an embodiment of the present invention, the number of equivalent sheet layers N of the (003) crystal plane of the above-mentioned cathode active material (003 ) and the number of equivalent sheet layers N of the (104) crystal plane (104) satisfy that N (003) *N (104) is 1×10 4 -3×10 4 , for example, 1×10 4 , 1.5×10 4 , 2×10 4 , 2.5×10 4 , 3×10 4 etc. According to a specific embodiment of the present invention, N (003) *N (104) is 1.5×10 4 -2.5×10 4 . Thus, the energy density, cycle performance, rate performance, and safety performance of the battery can be further improved.

[0044] According to an embodiment of the present invention, the number of equivalent sheet layers N of the (003) crystal plane of the positive electrode active material (003) (003) is 80 - 140, such as 80, 90, 100, 110, 120, 130, 140, etc. Further, the number of equivalent sheet layers N of the (003) crystal plane of the positive electrode active material (003) (003) is 90 - 130; the number of equivalent sheet layers N of the (104) crystal plane of the positive electrode active material (104) (104) is 130 - 200, such as 130, 140, 150, 160, 170, 180, 190, 200, etc. Further, the number of equivalent sheet layers of the (104) crystal plane of the positive electrode active material is 140 - 190.

[0045] The inventors found that when the number of equivalent sheet layers of the (003) crystal plane of the positive electrode active material is within the above range, on the one hand, it ensures that there are enough lithium sites in the overall layered framework to provide an accommodation space for active lithium and obtain the maximum reversible specific capacity; on the other hand, it has a stabilizing effect on the expansion and contraction of the c-axis during charge and discharge, can alleviate the structural distortion and collapse of the material, and endow the material with excellent cycle stability. The number of equivalent sheet layers of the (104) crystal plane of the positive electrode active material can indirectly reflect the stacking layers in the a-axis direction, represents the size of the flat layer, determines the number of lithium-ion sites that can be accommodated in each flat layer, and the length of the solid-phase migration path of lithium ions during insertion and extraction within the layer. When the number of equivalent sheet layers of the (104) crystal plane of the positive electrode active material is within the above range, the material can be endowed with the maximum reversible capacity and high-rate performance. Thus, the present invention controls the N (003) and N (104) within the above range, which can further improve the energy density, cycle performance, rate performance and safety performance of the battery.

[0046] Specifically, by performing calculations using the Scherrer formula and the Bragg formula on the XRD test results of the positive electrode active material, the average microcrystalline thickness D of the material along a certain crystal plane hkl and the crystal plane spacing d of the material along a certain crystal plane hkl can be obtained respectively. Taking N hkl = D hkl / d hkl to calculate the number of equivalent sheet layers of the microcrystals in the material along a specific crystal plane. For example

[0047] As an example, the above where K is the Scherrer constant 0.89, λ is the wavelength of the tested X-ray, β1 is the full width at half maximum of the diffraction peak of the (003) crystal plane in the microcrystals of the positive electrode active material, and θ1 is the Bragg diffraction angle of the (003) crystal plane in the microcrystals of the positive electrode active material; The above Wherein K is the Scherrer constant of 0.89, λ is the wavelength of the X-ray for testing, β2 is the full width at half maximum of the diffraction peak of the (104) crystal plane in the microcrystals of the positive electrode active material, and θ2 is the Bragg diffraction angle of the (104) crystal plane in the microcrystals of the positive electrode active material; Specifically, 2θ1 of the XRD diffraction characteristic peak corresponding to the (003) crystal plane is between 18.5° and 19.5°, and 2θ2 of the (104) crystal plane is between 44.0° and 44.5°.

[0048] According to an embodiment of the present invention, the average thickness D of the microcrystals of the positive electrode active material in the direction perpendicular to the (003) crystal plane (003) is 40 nm - 60 nm, such as 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, etc. Further, the average thickness D of the microcrystals of the positive electrode active material in the direction perpendicular to the (003) crystal plane (003) is 45 nm - 55 nm. Thus, when the average thickness D of the microcrystals of the positive electrode active material in the direction perpendicular to the (003) crystal plane (003) meets the above range, the material has a suitable microcrystal size in the c-axis direction, which can not only ensure the normal reversible capacity release, but also have a certain stabilizing effect during the expansion and contraction in the c-axis, endowing the material with excellent comprehensive performance in terms of capacity and cycle.

[0049] According to an embodiment of the present invention, the interplanar spacing d of the (003) crystal plane of the positive electrode active material (003) is 0.4730 nm - 0.4760 nm, such as 0.4730 nm, 0.4735 nm, 0.4740 nm, 0.4745 nm, 0.4750 nm, 0.4755 nm, 0.4760 nm, etc. Further, the interplanar spacing d of the (003) crystal plane of the positive electrode active material (003) is 0.4732 nm - 0.4750 nm. Thus, when the interplanar spacing d of the positive electrode active material in the (003) crystal plane (003) meets the above range, on the one hand, it is beneficial to the rapid insertion and extraction of lithium ions, improving the rate performance of the material; on the other hand, it can provide a certain space for the contraction and expansion of the unit cell in the c-axis direction, reducing the lattice distortion and microcrystal microstress, and improving the stability of the material.

[0050] According to an embodiment of the present invention, the average thickness D of the microcrystals of the positive electrode active material in the direction perpendicular to the (104) crystal plane (104) is 20 nm - 50 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc. Further, the average thickness D of the microcrystals of the positive electrode active material in the direction perpendicular to the (104) crystal plane (104) is 30 nm - 40 nm. Thus, the average thickness D of the microcrystals of the positive electrode active material in the direction perpendicular to the (104) crystal plane(104) Meeting the above range, the material has appropriate microcrystalline size in the a-axis direction, the material has an active structure and a lithium ion migration channel of appropriate size, ensuring that the material has high capacity and good rate performance.

[0051] According to an embodiment of the present invention, the interplanar spacing d of the (104) crystal plane of the positive electrode active material (104) is 0.2035 nm - 0.2045 nm, such as 0.2035 nm, 0.2037 nm, 0.2039 nm, 0.2040 nm, 0.2042 nm, 0.2044 nm, 0.2045 nm, etc. Further, the interplanar spacing d of the (104) crystal plane of the positive electrode active material (104) is 0.2037 nm - 0.2042 nm. Thus, when the interplanar spacing d of the positive electrode active material in the (104) crystal plane (104) meets the above range, it is beneficial to the rapid insertion and extraction of lithium ions, and can also relieve the cell contraction in the a-axis direction, improving the rate performance and cycle stability of the material.

[0052] According to an embodiment of the present invention, the positive electrode active material includes a matrix, and the matrix includes Li 1+ a Ni x Co y Mn z M m O2, -0.05 ≤ a ≤ 0.3, 0.8 ≤ x ≤ 1, 0 ≤ y ≤ 0.2, 0 ≤ z ≤ 0.2, 0.002 ≤ m ≤ 0.01, and M includes at least one of Sb, Nb, Mg, La, Ti, Al, Sr, Ba, Y, Zr, Ca, Fe, S, Zn, and Ta. Thus, the energy density, cycle performance, rate performance, and safety performance of the battery can be further improved.

[0053] According to some embodiments of the present invention, a1 in the Li 1+a Ni x Co y Mn z M m O2 satisfies -0.05 ≤ a ≤ 0.3, such as a being -0.05, -0.02, 0, 0.02, 0.05, 0.1, 0.2, 0.3, etc. Thus, including this content of lithium ions in the matrix can increase the specific capacity of the positive electrode active material, thereby enabling the battery to have a higher energy density.

[0054] According to some embodiments of the present invention, the Li 1+a Ni x Co y Mn z M mIn O2, x, y, z, and m satisfy 0.8 ≤ x ≤ 1, 0 ≤ y ≤ 0.2, 0 ≤ z ≤ 0.2, 0.002 ≤ m ≤ 0.01. For example, x can be 0.8, 0.85, 0.9, 0.95, 1, etc.; y can be 0, 0.1, 0.15, 0.2, etc.; z can be 0, 0.1, 0.15, 0.2, etc.; m can be 0.002, 0.005, 0.007, 0.01, etc.

[0055] According to an embodiment of the present invention, the positive electrode active material further includes a coating layer formed on at least a part of the surface of the matrix. The coating layer contains element J, and element J includes at least one of F, B, Cl, Br, I, S, Al, W, Co, Sn, and Mo. Thus, by forming a coating layer including element J on the matrix, the energy density, cycle performance, rate performance, and safety performance of the battery can be further improved simultaneously.

[0056] It should be noted that the existence form of element J in the above coating layer can include oxides and / or lithium oxides, which can be selected by those skilled in the art according to actual needs and will not be elaborated here.

[0057] In the second aspect of the present invention, the present invention provides a method for preparing the above positive electrode active material. According to an embodiment of the present invention, the method includes:

[0058] S100: Provide a positive electrode active material precursor

[0059] According to an embodiment of the present invention, the positive electrode active material precursor can be a commercially available product or prepared by the following steps:

[0060] Sa: Adjust a mixed system including nickel salt, cobalt salt, manganese salt, precipitant, and complexing agent to pH1, where the pH1 value is 9 - 12 to obtain precursor crystal nuclei. Specifically, mix a nickel salt solution, a cobalt salt solution, and a manganese salt solution according to the molar ratio of nickel element, cobalt element, and manganese element as x:y:z to obtain a mixed salt solution. Then, introduce nitrogen into the reaction kettle, and simultaneously add the mixed salt solution, precipitant (such as sodium hydroxide solution), and complexing agent (such as ammonia water) into the reaction kettle, and adjust the pH of the mixed system to pH1, where the pH1 value is 9 - 12, and fully react to form precursor crystal nuclei by coprecipitation.

[0061] Sb: When the Dv50 of the precursor crystal nuclei is 2 μm - 4 μm, adjust the mixed system to pH2, where the pH2 value is 9 - 13, and continuously add the mixed salt solution, precipitant, and complexing agent, so that nickel ions, cobalt ions, and manganese ions in the mixed salt solution continue to undergo coprecipitation reaction with the precursor crystal nuclei as seeds to obtain the positive electrode active material precursor, where the pH2 value is greater than the pH1 value. As an example, the difference between the pH2 value and the pH1 value is 0.1 - 1.

[0062] The method for preparing the precursor of the positive electrode active material of the present invention is simple and feasible. By controlling the pH value, a precursor with a specific number of equivalent lamella layers on the crystal plane can be synthesized, thereby affecting the microcrystalline structure in the primary particles of the positive electrode active material.

[0063] According to an embodiment of the present invention, the Dv50 of the precursor of the positive electrode active material is 9 μm - 20 μm, such as 9 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, etc.

[0064] In the present invention, Dv50 refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50%. Referring to the standard GB / T19077 - 2016, it is measured using a laser particle size analyzer (such as Malvern Master Size 3000).

[0065] According to an embodiment of the present invention, the number of equivalent lamella layers N on the (101) crystal plane of the precursor of the positive electrode active material (101) is 60 - 120, such as 60, 70, 80, 90, 100, 110, 120, etc. Further, the number of equivalent lamella layers N on the (101) crystal plane of the precursor of the positive electrode active material (101) is 60 - 90; the number of equivalent lamella layers N on the (001) crystal plane of the precursor of the positive electrode active material (001) is 20 - 60, such as 20, 30, 40, 50, 60, etc. Further, the number of equivalent lamella layers N on the (001) crystal plane of the precursor of the positive electrode active material (001) is 20 - 50; the number of equivalent lamella layers N on the (100) crystal plane of the precursor of the positive electrode active material (100) is 110 - 140, such as 110, 120, 130, 140, etc. Further, the number of equivalent lamella layers N on the (100) crystal plane of the precursor of the positive electrode active material (100) is 110 - 130.

[0066] Thus, when the number of equivalent lamella layers N on the (101) crystal plane of the precursor of the positive electrode active material (101) , the number of equivalent lamella layers N on the (001) crystal plane (001) and the number of equivalent lamella layers N on the (100) crystal plane (100) meet the above ranges, the precursor has a wide pyrometallurgical temperature tolerance range. When the sintering temperature is increased, the positive electrode active material can be fully lithiated, obtaining high crystallinity and fewer crystal defects, and the precursor can withstand high temperatures without the continuous growth of the positive electrode crystals resulting in an excessive number of equivalent lamella layers on the crystal plane. Thus, the precursor that meets the above number of equivalent lamella layers on the crystal plane can simplify the pyrometallurgical process, thereby improving the capacity and rate performance of the prepared positive electrode active material.

[0067] It should be noted that the number of equivalent lamella layers N on the (101) crystal plane of the precursor of the positive electrode active material(101) 、The number of equivalent sheet layers N of the (001) crystal plane (001) and the number of equivalent sheet layers N of the (100) crystal plane (100) are tested in the same way as N of the above positive electrode active material (003) and N (104) . For example where D (101) is the average thickness perpendicular to the (101) crystal plane direction in the microcrystals of the positive electrode active material precursor, with the unit of nm, and d (101) is the interplanar spacing of the (101) crystal plane in the microcrystals of the positive electrode active material precursor, with the unit of nm; D (001) is the average thickness perpendicular to the (001) crystal plane direction in the microcrystals of the positive electrode active material precursor, with the unit of nm, and d (001) is the interplanar spacing of the (001) crystal plane in the microcrystals of the positive electrode active material precursor, with the unit of nm; D (100) is the average thickness perpendicular to the (100) crystal plane direction in the microcrystals of the positive electrode active material precursor, with the unit of nm, and d (100) is the interplanar spacing of the (100) crystal plane in the microcrystals of the positive electrode active material precursor, with the unit of nm.

[0068] As an example, the above where K is the Scherrer constant 0.89, λ is the wavelength of the tested X-ray, β3 is the full width at half maximum of the diffraction peak of the (101) crystal plane in the microcrystals of the positive electrode active material precursor, and θ3 is the Bragg diffraction angle of the (101) crystal plane in the microcrystals of the positive electrode active material precursor; The above where K is the Scherrer constant 0.89, λ is the wavelength of the tested X-ray, β4 is the full width at half maximum of the diffraction peak of the (001) crystal plane in the microcrystals of the positive electrode active material, and θ4 is the Bragg diffraction angle of the (104) crystal plane in the microcrystals of the positive electrode active material; The above where K is the Scherrer constant 0.89, λ is the wavelength of the tested X-ray, β5 is the full width at half maximum of the diffraction peak of the (100) crystal plane in the microcrystals of the positive electrode active material precursor, and θ5 is the Bragg diffraction angle of the (100) crystal plane in the microcrystals of the positive electrode active material precursor,

[0069] S200: First, mix and sinter the positive electrode active material precursor with a lithium source and a dopant containing element M

[0070] According to an embodiment of the present invention, the cathode active material precursor obtained in the above steps is subjected to a first mixed sintering with a lithium source and a dopant containing element M in an oxygen-containing atmosphere. Wherein, the temperature of the first mixed sintering is 650°C - 900°C, for example, the sintering temperature is 650°C, 680°C, 700°C, 720°C, 750°C, 780°C, 800°C, 820°C, 850°C, 880°C, 900°C, and the time is 4h - 15h, for example, 4h, 6h, 8h, 10h, 12h, 15h, etc. Then, it is naturally cooled to make the sintered compound drop to room temperature. After crushing, sieving, and iron removal, the cathode active material after the first sintering is obtained. Thus, by selecting a specific doping element M, it can control the growth of the microcrystals of the cathode active material in the lithiation stage, and combined with the above sintering conditions, it can achieve the control of the equivalent number of sheet layers and the interplanar spacing of the crystal planes of the cathode active material.

[0071] As an example, the above nickel salt, cobalt salt, and manganese salt can adopt the corresponding chlorides, carbonates, and sulfates of each element, and the lithium source and the dopant containing element M can adopt at least one of the corresponding chlorides, carbonates, sulfates, and oxides.

[0072] Thus, by using this method, the above cathode active material can be prepared, so that the battery loaded with it takes into account high energy density, cycle performance, rate performance, and safety performance.

[0073] According to an embodiment of the present invention, the method for preparing the cathode active material further includes:

[0074] S300: The cathode active material after the first sintering obtained in step S200 is subjected to a second mixed sintering with a coating agent containing element J in an oxygen-containing atmosphere. The temperature of the second mixed sintering is 200°C - 700°C, for example, 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, etc., and the time is 3h - 10h, for example, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc., so as to form a coating layer containing element J on at least part of the surface of the cathode active material after the first sintering. Then, after natural cooling, crushing, sieving, and iron removal, the cathode active material is obtained. Thus, by forming a coating layer containing element J on the outer surface of the cathode active material, it can reduce the side reaction between the core of the cathode active material and the electrolyte, thereby improving the cycle stability of the cathode active material.

[0075] It should be noted that the features and advantages described above for the cathode active material also apply to the method for preparing the cathode active material, and will not be elaborated here.

[0076] In the third aspect of the present invention, the present invention provides a positive electrode sheet. According to an embodiment of the present invention, the positive electrode sheet comprises the positive electrode active material described in the first aspect of the present invention or the positive electrode active material obtained by the method described in the second aspect of the present invention.

[0077] According to an embodiment of the present invention, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector. The positive electrode active material layer comprises the above-mentioned positive electrode active material, wherein the positive electrode current collector can be a metal foil or a composite current collector (a composite current collector can be formed by disposing a metal material on a polymer substrate). For example, the positive electrode current collector can be an aluminum foil.

[0078] According to some embodiments of the present invention, the positive electrode active material layer may further optionally comprise a binder. As an example, the binder may comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, or fluorinated acrylate resin.

[0079] According to some embodiments of the present invention, the positive electrode active material layer may further optionally comprise a conductive agent. As an example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0080] According to some embodiments of the present invention, the positive electrode sheet can be prepared in the following manner: dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0081] It should be noted that the features and advantages described above for the positive electrode active material and its preparation method also apply to the positive electrode sheet, and will not be elaborated here.

[0082] In the fourth aspect of the present invention, the present invention provides a battery. According to an embodiment of the present invention, the battery comprises the above-mentioned positive electrode sheet.

[0083] As an example, the battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. The separator is located between the positive electrode sheet and the negative electrode sheet. During the charge and discharge process of the battery, active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows ions to pass through.

[0084] According to an embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material. The negative electrode current collector can be a metal foil or a composite current collector (a composite current collector can be formed by disposing a metal material on a polymer substrate). For example, the positive electrode current collector can be a copper foil.

[0085] According to some embodiments of the present invention, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0086] According to some embodiments of the present invention, the negative electrode active material layer may also optionally include a conductive agent. The conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0087] According to some embodiments of the present invention, the negative electrode active material layer may also optionally include other additives, such as a thickening agent (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0088] According to some embodiments of the present invention, the negative electrode sheet can be prepared in the following manner: dispersing the above components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, and the binder, in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode sheet can be obtained.

[0089] According to still some other embodiments of the present invention, the negative electrode sheet may include a lithium metal sheet or a lithium alloy, etc., such as a lithium indium alloy.

[0090] According to yet some other embodiments of the present invention, the type of the separator is not particularly limited, and any publicly known porous structure separator with good chemical stability and mechanical stability can be selected. As an example, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0091] According to yet some other embodiments of the present invention, the type of the electrolyte is not specifically limited and can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid-state. According to some specific embodiments of the present invention, the electrolyte uses an electrolytic solution, and the electrolytic solution includes a lithium salt and a solvent.

[0092] According to some specific embodiments of the present invention, the lithium salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, or lithium tetrafluoro(oxalato)phosphate.

[0093] According to some specific embodiments of the present invention, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethylene glycol dimethyl ether, methyl ethyl sulfone, or diethyl sulfone.

[0094] In some embodiments of the present application, the electrolyte may further optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0095] It should be noted that the features and advantages described above for the positive electrode sheet also apply to this solid-state battery and will not be elaborated here.

[0096] In the fifth aspect of the present invention, the present invention provides an electrical device. According to an embodiment of the present invention, the electrical device includes the above battery. According to an embodiment of the present invention, the electrical device may include, but is not limited to, mobile phones, laptop computers, electric vehicles, etc.

[0097] It should be noted that the features and advantages described above for the battery also apply to this electrical device and will not be elaborated here.

[0098] Hereinafter, embodiments of the present invention will be described. The embodiments described below are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention. For those technologies or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0099] Example 1

[0100] (1) Dissolve nickel sulfate, cobalt sulfate, and manganese sulfate in pure water according to a molar ratio of nickel element, cobalt element, and manganese element of 84:10:6 to obtain a mixed salt solution with a concentration of 2 mol / L. Prepare a sodium hydroxide solution with a concentration of 8 mol / L as a precipitant solution, and prepare an ammonia water solution with a concentration of 6 mol / L as a complexing agent solution. Add the sodium hydroxide and ammonia water solutions to the reaction kettle, adjust the pH1 to 10.9, protect with nitrogen, control the reaction system temperature at 60 °C, add the mixed salt solution, sodium hydroxide solution, and ammonia water into the reaction kettle through the inlet pipeline respectively, keep the stirring speed at 500 rpm, control the inlet flow rate of the mixed salt solution at 200 mL / h, adjust the flow rates of the sodium hydroxide solution and ammonia water to keep the pH of the reaction system stable at 10.9 ± 0.05. After the Dv50 of the precursor crystal nuclei in the reaction system grows to 3.0 μm, adjust the solution pH2 to 11.3 ± 0.05, adjust the flow rate of the mixed salt solution to 500 mL / h, increase the stirring speed to 700 rpm, keep the reaction temperature unchanged. After the average particle size Dv50 in the solution grows to 14 μm, age for 1 h, separate, wash, and dry to obtain the precursor of the positive electrode active material;

[0101] (2) Weigh the above precursor, lithium hydroxide, and niobium pentoxide according to a molar ratio of the sum of nickel, cobalt, and manganese elements in the precursor, lithium element, and niobium element of 1:1.03:0.007 respectively, mix them evenly in a mixer, sinter them at a constant temperature in an oxygen furnace. The oxygen concentration in the oxygen-containing gas in the oxygen furnace is greater than 95 vol%, the heating rate is 5 °C / min, the sintering temperature is 810 °C, and the sintering time is 10 h. After naturally cooling to room temperature, crush, screen, and remove iron to obtain the first-fired material of the positive electrode active material;

[0102] (3) Mix the first-fired material of the positive electrode active material and boric acid evenly in a high-speed mixer according to a molar ratio of the sum of transition metal elements in the first-fired material of the positive electrode active material to boron element of 1:0.001, sinter them at a constant temperature of 350 °C in an oxygen furnace. The oxygen concentration in the oxygen-containing gas in the oxygen furnace is greater than 90 vol%, the sintering time is 10 h. After cooling, screening, and removing iron, obtain the positive electrode active material Li 1.03 Ni 0.813 Co 0.100 Mn 0.060 Nb 0.004 P 0.003 O2@B. In the chemical formula of the positive electrode active material, the part before @ is the matrix component, and the main element in the coating layer is after @.

[0103] Examples 2 - 8 and Comparative Examples 1 - 7

[0104] Prepare the positive electrode active material according to the method of Example 1. The differences in the material composition and specific process conditions are shown in Table 1.

[0105] In Example 2, magnesium oxide is used as the dopant and boric acid is used as the coating agent.

[0106] In Example 3, tantalum pentoxide is used as the dopant and boric acid is used as the coating agent.

[0107] In Example 4, magnesium oxide is used as the dopant and tungsten trioxide is used as the coating agent.

[0108] In Example 5, molybdenum oxide is used as the dopant and tungsten trioxide is used as the coating agent.

[0109] In Example 6, niobium pentoxide and antimony trioxide are used as the dopants and boric acid is used as the coating agent.

[0110] In Example 7, strontium oxide and antimony trioxide are used as the dopants and boric acid is used as the coating agent.

[0111] In Example 8, niobium pentoxide is used as the dopant and no coating agent is used.

[0112] In Comparative Example 1, aluminum oxide and niobium pentoxide are used as the dopants and boric acid is used as the coating agent.

[0113] In Comparative Example 2, niobium pentoxide is used as the dopant and boric acid is used as the coating agent.

[0114] In Comparative Example 3, niobium pentoxide and ammonium dihydrogen phosphate are used as the dopants and boric acid is used as the coating agent.

[0115] In Comparative Example 4, no dopant is used and boric acid is used as the coating agent.

[0116] In Comparative Example 5, antimony trioxide is used as the dopant and boric acid is used as the coating agent.

[0117] In Comparative Example 6, niobium pentoxide is used as the dopant and boric acid is used as the coating agent.

[0118] In Comparative Example 7, niobium pentoxide is used as the dopant and boric acid is used as the coating agent.

[0119] Table 1

[0120]

[0121]

[0122] Note: In Table 1, in Example 6, when the doping elements include Nb and Sb, the molar ratio of the precursor, lithium source, and dopant to the (Ni + Co + Mn) element, lithium element, and M element should be understood as the molar ratio of the precursor, lithium source, and dopant to the (Ni + Co + Mn) element, lithium element, Nb element, and Sb element. The same applies to other examples and comparative examples.

[0123] The equivalent number of lamellae of the precursor crystal planes and the composition of the cathode active material obtained in Examples 2-8 and Comparative Examples 1-7 are shown in Table 2.

[0124] Table 2

[0125]

[0126]

[0127] The average thickness D perpendicular to the (003) crystal plane direction in the microcrystals of the cathode active material obtained in Examples 2-8 and Comparative Examples 1-7 (003) , the (003) crystal plane spacing d in the microcrystals of the cathode active material (003) , the average thickness D perpendicular to the (104) crystal plane direction in the microcrystals of the cathode active material (104) , the (104) crystal plane spacing d in the microcrystals of the cathode active material (104) , the equivalent number of lamellae N of the cathode active material crystal plane (003) and the equivalent number of lamellae N of the (104) crystal plane of the cathode active material (104) and N (003) *N (104) are shown in Table 3.

[0128] Table 3

[0129]

[0130]

[0131] The cathode active materials obtained in Examples 1-8 and Comparative Examples 1-7 were assembled into 2025-type coin cells, and the initial Coulombic efficiency, cycling performance, rate performance, and lithium ion diffusion coefficient of the cells were characterized. The characterization results are shown in Table 4.

[0132] The preparation process of the 2025-type coin cell is as follows:

[0133] Preparation of the cathode electrode sheet: The cathode active material, acetylene black, and polyvinylidene fluoride (PVDF) were thoroughly mixed in a mass ratio of 95:3:2 with an appropriate amount of N-methylpyrrolidone (NMP) to form a uniform slurry. The slurry was coated on both surfaces of the aluminum foil and dried at 120 °C for 12 h, and then stamped into shape under a pressure of 100 MPa to make a cathode electrode sheet with a diameter of 12 mm and a thickness of 120 μm. Among them, the loading amount of the cathode active material on the aluminum foil was 15-16 mg / cm 2 ;

[0134] Battery Assembly: Inside an argon-filled glove box with a water content and an oxygen content both less than 5 ppm, the positive electrode sheet, separator, negative electrode sheet, and electrolyte are assembled into a 2025-type button cell, and then left standing for 6 h. Among them, the negative electrode sheet uses a metallic lithium sheet with a diameter of 17 mm and a thickness of 1 mm; the separator uses a polyethylene porous membrane (Celgard 2325) with a thickness of 25 μm; the electrolyte includes the lithium salt LiPF6 and a solvent (ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1), and the concentration of LiPF6 in the electrolyte is 1 mol / L.

[0135] First-cycle Coulombic Efficiency Test:

[0136] At 25 °C, the battery is charged at a constant current of 0.1C to 4.4V, and then charged at a constant voltage to 0.02C to obtain the first-cycle charge specific capacity C0 of the battery. Then, it is discharged at a constant current of 0.1C to 3.0V to obtain the first-cycle discharge specific capacity C1 of the battery. The first-cycle Coulombic efficiency of the battery = C1 / C0 × 100%.

[0137] Control the charge-discharge voltage range to be 3.0 - 4.3V. At room temperature, perform charge-discharge tests on the button cell at 0.1C to evaluate the electrochemical performance of the multi-component positive electrode material.

[0138] Cycling Performance Test: At 45 °C, the battery is charged at a constant current of 1C to 4.3V to obtain the first-cycle charge specific capacity C2 of the battery. Then, it is discharged at a constant current of 1C to 3.0V, and then charged and discharged cyclically at a constant current of 1C for 80 cycles. Take the discharge specific capacity C of the 80th cycle. 80 The first-cycle Coulombic efficiency of the battery = C 80 / C2 × 100%.

[0139] Rate Performance Test: Control the charge-discharge voltage range to be 3.0 - 4.3V. At room temperature, charge and discharge the button cell at 0.1C for 2 cycles, and then charge and discharge it at 0.2C, 0.33C, 0.5C, and 1C for 1 cycle respectively. The rate performance of the battery is characterized by the ratio of the first-cycle discharge specific capacity at 0.1C to the discharge specific capacity at 1C. Among them, the first-cycle discharge specific capacity at 0.1C is the discharge specific capacity of the button cell in the 1st week cycle, and the discharge specific capacity at 1C is the discharge specific capacity of the button cell in the 6th week cycle.

[0140] Diffusion Coefficient Test: Adopt EIS test and analysis. Charge the battery at a constant current of 0.1C to 4.3V, charge at a constant voltage for 30 min, and then discharge at a constant current of 0.1C to 3.0V; then charge at a constant current of 0.1C to 4.3V again, remove the fully charged half-cell, and perform EIS test in the frequency range of (100) kHz to 0.01 Hz with an amplitude of 10 mV. According to the following formula, the slope σ of the fitting line of Z re and ω -1 / 2 can be obtained:

[0141] Z re = R s + R ct + σω -1 / 2

[0142] ω = 2πf

[0143] Among them, Z re is the real part of the impedance spectrum obtained from the test, R s is the solution resistance, R ct is the charge transfer resistance, ω is the angular frequency, f is the test frequency, and σ is the Warburg factor.

[0144] Then, according to the calculation formula of the lithium ion diffusion coefficient, the bulk phase Li + diffusion coefficient D Li + :

[0145] D Li + = R 2 T 2 / (2A 2 n 4 F 4 C 2 σ 2 )

[0146] Among them, R is the ideal gas constant, T is the absolute temperature, A is the cross-sectional area of the electrode, n is the number of electron transfers, F is the Faraday constant, and C is the lithium ion concentration in the electrode.

[0147] Table 4

[0148]

[0149]

[0150] It can be seen from Table 3 that the N (003) *N (104) of the positive electrode active material in Examples 1-8 is 1×10 4 -3×10 4 , while the N (003) *N (104) of the positive electrode active material in Comparative Examples 1-7 are not within the range of 1×10 4 -3×10 4 . It can be seen from Table 4 that the charge specific capacity, discharge specific capacity, first-cycle Coulomb efficiency, rate performance, and capacity retention rate of the batteries in Examples 1-8 are significantly higher than those of the batteries in Comparative Examples 1-7. At the same time, the lithium ion diffusion coefficient can also be maintained within a suitable range. Thus, it is shown that using N (003) *N (104) of 1×104 -3*10 4 The positive electrode active material can enable the battery loaded with it to have both high energy density, cycle performance and rate performance.

[0151] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0152] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A positive electrode active material, characterized in that: The positive electrode active material comprises a plurality of primary particles, and the positive electrode active material (003) has an equivalent number of flakes N (003) The number of equivalent layers N to the (104) crystal plane (104) Satisfy: N (003) ×N (104) 1×10 4 -21108, , , where D （003） is the average thickness of the positive electrode active material microcrystal perpendicular to the (003) crystal plane, in nm, d （003） is the (003) interplanar spacing in the positive electrode active material microcrystals, in nm, D （104） is the average thickness of the positive electrode active material microcrystals perpendicular to the (104) crystal plane, in nm, d （104） is the (104) interplanar spacing in the positive electrode active material microcrystals, in nm; The positive electrode active material (003) has an equivalent number of flakes N (003) The positive electrode active material (104) has a crystal plane equivalent layer number N (104) 130-200; The average thickness D of the positive electrode active material microcrystals perpendicular to the (003) crystal plane (003) 40nm-60nm; The positive electrode active material is prepared using a positive electrode active material precursor, and the positive electrode active material precursor is prepared using the following method: Adjusting the mixed system including nickel salt, cobalt salt, manganese salt, precipitant and complexing agent to pH 1, wherein the pH 1 value is 9-12, so as to obtain precursor crystal nuclei; When the Dv50 of the precursor crystal nucleus is 2 μm-4 μm, the mixed system is adjusted to pH 2, and the pH 2 value is 9-13, so as to obtain a positive electrode active material precursor, Among them, the pH2 value is greater than the pH1 value.

2. The positive electrode active material according to claim 1, characterized in that The N (003) ×N (104) 1.5×10 4 -2.5×10 4 .

3. The positive electrode active material according to claim 1, characterized in that The positive electrode active material (104) has a crystal plane equivalent layer number N (104) It is 140-190.

4. The positive electrode active material according to claim 1, characterized in that The average thickness D of the positive electrode active material microcrystals perpendicular to the (003) crystal plane (003) It is 45nm-55nm.

5. The positive electrode active material according to claim 1, characterized in that The positive electrode active material (003) has an equivalent number of flakes N (003) It is 90-130.

6. The positive electrode active material according to claim 1 or 2, characterized in that: The average thickness D of the positive electrode active material microcrystals perpendicular to the (003) crystal plane (003) It is 45nm-55nm.

7. The positive electrode active material according to claim 6, characterized in that The (003) crystal plane spacing d of the positive electrode active material (003) It is 0.4730nm-0.4760nm.

8. The positive electrode active material according to claim 7, characterized in that The (003) crystal plane spacing d of the positive electrode active material (003) It is 0.4732nm-0.4750nm.

9. The positive electrode active material according to claim 6, characterized in that The average thickness D of the positive electrode active material microcrystals perpendicular to the (104) crystal plane (104) It is 20nm-50nm.

10. The positive electrode active material according to claim 9, characterized in that The average thickness D of the positive electrode active material microcrystals perpendicular to the (104) crystal plane (104) It is 30nm-40nm.

11. The positive electrode active material according to claim 6, characterized in that The (104) interplanar spacing d of the positive electrode active material (104) It is 0.2035nm-0.2045nm.

12. The positive electrode active material according to claim 11, characterized in that The (104) interplanar spacing d of the positive electrode active material (104) It is 0.2037nm-0.2042nm.

13. The positive electrode active material according to claim 1, characterized in that The positive electrode active material includes a matrix, and the matrix includes Li 1+a Ni x Co y Mn z M m O2, -0.05≤a≤0.3, 0.8≤x≤1, 0≤y≤0.2, 0≤z≤0.2, 0.002≤m≤0.01, M includes at least one of Sb, Nb, Mg, La, Ti, Al, Sr, Ba, Y, Zr, Ca, Fe, S, Zn and Ta.

14. The positive electrode active material according to claim 1, characterized in that It also includes a coating layer, which is formed on at least a portion of the surface of the substrate, and the coating layer contains J element, and the J element includes at least one of F, B, Cl, Br, I, S, Al, W, Co, Sn and Mo.

15. A method for preparing the positive electrode active material according to any one of claims 1 to 14, characterized in that: include: Providing a positive electrode active material precursor; The positive electrode active material precursor is first mixed with a lithium source and a dopant containing an element M and sintered to obtain a positive electrode active material first sintered material.

16. The method according to claim 15, characterized in that The difference between pH2 and pH1 is 0.1-1.

17. The method according to claim 15, characterized in that The positive electrode active material precursor satisfies at least one of the following conditions: The Dv50 of the positive electrode active material precursor is 9 μm-20 μm; The positive electrode active material precursor (101) has a crystal plane equivalent layer number N (101) 60-120; The positive electrode active material precursor (001) crystal plane equivalent layer number N (001) 20-60; The positive electrode active material precursor (100) has a crystal plane equivalent layer number N (100) It is 110-140.

18. The method according to claim 17, characterized in that The positive electrode active material precursor (101) has a crystal plane equivalent layer number N (101) It is 60-90.

19. The method according to claim 17, characterized in that The positive electrode active material precursor (001) crystal plane equivalent layer number N (001) It is 20-50.

20. The method according to claim 17, characterized in that The positive electrode active material precursor (100) has a crystal plane equivalent layer number N (100) It is 110-130.

21. The method according to claim 15, characterized in that The temperature of the first mixed sintering is 650° C.-900° C., and the time is 4 h-15 h.

22. The method according to claim 15, characterized in that The method further includes performing a second mixed sintering on the positive electrode active material 1 and the coating agent containing element J, so as to form a coating layer containing element J on at least a portion of the surface of the positive electrode active material 1.

23. The method according to claim 22, characterized in that The temperature of the second mixed sintering is 200° C.-700° C., and the time is 3 h-10 h.

24. A positive electrode plate, characterized in that: The invention comprises the positive electrode active material according to any one of claims 1 to 14 or the positive electrode active material obtained by the method according to any one of claims 15 to 23.

25. A battery, characterized in that: Including the positive electrode sheet as described in claim 24.

26. An electrical equipment, characterized in that: Comprising the battery of claim 25.

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