High-nickel positive electrode active material, preparation method therefor, and use thereof

Abstract

The present application provides a high-nickel positive electrode active material, a preparation method therefor, and a use thereof. The high-nickel positive electrode active material comprises the chemical composition LiaNibMnmConXcO2, where 0.95 ≤ a ≤ 1.05, 0.90 ≤ b ≤ 0.98, 0 < c ≤ 0.016, and b + m + n = 1; X comprises at least two of Zr, Ti, W, B, Sn, Ta, Al, Mo, Co, and Ce. The lithium-nickel mixing ratio of the high-nickel positive electrode active material is 0.009-0.015; in an X-ray diffraction pattern, c / a is 4.8-5.2, and I(003) / I(104) is 1.8-2.4. Due to the low lithium-nickel mixing ratio and the high c / a and I(003) / I(104), the high-nickel positive electrode active material, when used in a lithium-ion battery, can significantly improve the capacity and initial Coulombic efficiency of the battery.

Description

A high-nickel positive electrode active material, preparation method and application thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 7, 2024, with application number 202410264547.6 and application name “A high nickel positive electrode active material, preparation method and application thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of lithium-ion batteries and relates to a high-nickel positive electrode active material, and in particular to a high-nickel positive electrode active material, a preparation method and an application thereof. Background Art

[0003] Lithium-ion batteries are widely used in portable electronic devices, power tools, special equipment, special aerospace, as well as energy storage power systems such as hydropower, thermal power, wind power and solar power stations due to their high energy density, low self-discharge rate, no memory effect, wide operating temperature range, safe use and environmental protection. However, current lithium-ion batteries still cannot meet people's needs for charging and discharging efficiency, cycle life and capacity.

[0004] As a crucial component of lithium-ion batteries, cathode active materials account for a significant proportion of their composition, and their performance significantly impacts battery performance. High-nickel cathode materials can achieve a gram capacity exceeding 200 mAh / g, effectively increasing the energy density of lithium-ion batteries. However, during the sintering process, the particles of lithium and nickel ions in high-nickel cathode active materials have similar radii, causing them to occupy each other's positions. This can easily lead to lithium-nickel intermixing, resulting in poor initial efficiency and capacity.

[0005] Therefore, it is very necessary to develop a high-Ni cathode active material with high first coulombic efficiency and high capacity. Summary of the Invention

[0006] In view of the above-mentioned defects, the present application provides a high-nickel positive electrode active material, which has high first coulombic efficiency and capacity.

[0007] The present application provides a method for preparing a high-nickel positive electrode active material. The high-nickel positive electrode active material prepared by the preparation method has high first coulombic efficiency and capacity.

[0008] The present application provides a positive electrode sheet, which includes the above-mentioned high-nickel positive electrode active material or the high-nickel positive electrode active material prepared by the above-mentioned preparation method. Applying the positive electrode sheet to a lithium-ion battery can effectively improve the capacity and first coulombic efficiency of the lithium-ion battery.

[0009] The present application provides a lithium-ion battery, which includes the above-mentioned high-nickel positive electrode active material or the high-nickel positive electrode active material prepared by the above-mentioned preparation method or the above-mentioned positive electrode sheet, and the lithium-ion battery has high first coulombic efficiency and capacity.

[0010] The present application provides a high nickel positive electrode active material, including the chemical composition shown in Formula 1, Li a Ni b Mn m Co n X c O2 Formula 1

[0011] In formula 1, 0.95≤a≤1.05, 0.90≤b≤0.98, 0<c≤0.016, b+m+n=1, and X includes at least two of Zr, Ti, W, B, Sn, Ta, Al, Mo, Co, and Ce;

[0012] The lithium-nickel mixing ratio of the high-nickel positive electrode active material is 0.009 to 0.015;

[0013] In the X-ray diffraction pattern of the high-nickel positive electrode active material, c / a is 4.8 to 5.2;

[0014] In the X-ray diffraction pattern of the high nickel positive electrode active material, the peak areas of the diffraction peaks at 2θ of 18.8±0.5° and 44.3±0.5° are respectively 1 (003) , I (104) , and I (003) / I (104) It is 1.8 to 2.4.

[0015] Furthermore, the high nickel positive electrode active material includes a core layer and a coating layer covering at least a portion of the surface of the core layer; the core layer includes a first core layer and a second core layer covering at least a portion of the surface of the first core layer; the first core layer has a chemical composition of Formula 2, the second core layer has a chemical composition of Formula 3, and the coating layer has a chemical composition of Formula 4, Li d Ni e Mn f Co g X 1 h O2 Formula 2 LiX 2 O2 Formula 3 LiX 3 O2 Formula 4

[0016] In formula 2, 0.95≤d≤1.05, 0.9≤e≤0.98, e+f+g=1, 0<h≤0.016, X 1 including at least two of Zr, Ti, W, B, Sn, Ta, and Ce;

[0017] In formula 3, X 2 Including at least one of Zr, Ti, W, B, Sn, Ta, Al, Mo, and Co;

[0018] In formula 4, X 3 Includes at least one of W, Al, B, and Co.

[0019] Furthermore, the first core layer further comprises F element; the mass percentage of F element in the first core layer is 0.01 to 0.045 wt %.

[0020] Furthermore, the high-nickel positive electrode active material includes secondary particles composed of primary particles; the median particle size of the primary particles is 0.2 to 1 μm.

[0021] Furthermore, the median particle size of the high-nickel positive electrode active material is 0.7 to 1.5 μm.

[0022] Furthermore, the specific surface area of ​​the high nickel positive electrode active material is 0.9 to 5 m 2 / g.

[0023] Furthermore, the powder compaction density of the high nickel positive electrode active material is 3.1 to 3.4 g / cm 3 .

[0024] The present application also provides a method for preparing a high-nickel positive electrode active material, comprising the following steps:

[0025] (1) Ni x Co y Mn z (OH)2 is calcined at 400-600°C for 1-5 hours, and then ground and crushed to obtain a first product having a median particle size D50 < 0.8 μm, wherein 0.90 ≤ x ≤ 0.98, and x + y + z = 1;

[0026] (2) mixing the first product, a lithium source, and a dopant to obtain a first mixed raw material, and performing a first sintering in an oxygen atmosphere at a sintering temperature of 600 to 850° C. and a sintering time of 15 to 20 hours to obtain a second product; wherein the molar ratio of lithium in the lithium source to the first product is 0.95 to 1.05, and the mass ratio of the dopant to the theoretical generated mass of the high-nickel positive electrode active material is (0.1 to 10):1000;

[0027] (3) mixing the second product and the first coating agent and performing a second sintering in an oxygen atmosphere at a sintering temperature of 500 to 600° C. for 8 to 12 hours to obtain a third product;

[0028] (4) The third product and the second coating agent are mixed and subjected to a third sintering under a protective atmosphere at a sintering temperature of 300 to 400° C. and a sintering time of 6 to 8 hours to obtain the high-nickel positive electrode active material.

[0029] Furthermore, the first mixed raw material also includes a fluorine source; the mass ratio of the fluorine source to the theoretical generated mass of the high-nickel positive electrode active material is (1-10):10000.

[0030] Furthermore, the heating rate during the first sintering process is 1-4°C / min.

[0031] Furthermore, the heating rate during the second sintering process is 1-3°C / min.

[0032] Furthermore, the heating rate during the third sintering process is 1-3°C / min.

[0033] The present application also provides a positive electrode sheet, comprising any of the high-nickel positive electrode active materials described above, or comprising a high-nickel positive electrode active material prepared by any of the methods for preparing the high-nickel positive electrode active materials described above.

[0034] The present application also provides a lithium-ion battery, comprising any of the high-nickel positive electrode active materials described above, or comprising a high-nickel positive electrode active material prepared by any of the methods for preparing the high-nickel positive electrode active materials described above, or comprising the positive electrode sheet described above.

[0035] The high nickel positive electrode active material of the present application has the chemical composition shown in Formula 1, and its lithium nickel mixing ratio is low, which is 0.009-0.015, and will not hinder the insertion and extraction of lithium ions; at the same time, in the X-ray diffraction pattern of the positive electrode active material, c / a is 4.8-5.2, I (003) / I (104) The ratio is 1.8 to 2.4, which is a large value. This increases the content of layered structure in the high-nickel positive electrode material, thereby increasing the number of lithium ions that can move freely inside the material. During the charge and discharge process, the lithium ions can migrate smoothly, effectively improving the first coulombic efficiency and capacity of the positive electrode active material. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a SEM image of the high nickel positive electrode active material in Example 1 of the present application;

[0037] FIG2 is a SEM image of the high nickel positive electrode active material in Example 2 of the present application;

[0038] FIG3 is a SEM image of the high nickel positive electrode active material in Example 3 of the present application;

[0039] FIG4 is a SEM image of the high-nickel positive electrode active material in Example 4 of the present application. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] The first aspect of the present application provides a high nickel positive electrode active material, including the chemical composition shown in Formula 1, Li a Ni b Mn m Co n X c O2 Formula 1

[0042] In formula 1, 0.95≤a≤1.05, 0.90≤b≤0.98, 0<c≤0.016, b+m+n=1, and X includes at least two of Zr, Ti, W, B, Sn, Ta, Al, Mo, Co, and Ce;

[0043] The lithium-nickel mixing ratio of high-nickel positive electrode active materials is 0.009-0.015;

[0044] In the X-ray diffraction pattern of high nickel positive electrode active materials, c / a is 4.8 to 5.2;

[0045] In the X-ray diffraction pattern of the high nickel positive electrode active material, the peak areas of the diffraction peaks at 2θ of 18.8±0.5° and 44.3±0.5° are respectively I (003) , I (104) , and I (003) / I (104) It is 1.8 to 2.4.

[0046] Specifically, the nickel-lithium mixing rate of the high-nickel positive electrode active material can be tested by XRD testing; the c / a and I (003) / I (104) Conduct a test.

[0047] According to the above solution provided by the present application, the high nickel positive electrode active material is applied to lithium ion batteries, which can effectively improve the capacity and initial coulombic efficiency of the battery. The inventors have analyzed this principle and believe that the reason may be that when the high nickel positive electrode active material has the chemical composition shown in Formula 1, and the lithium nickel mixing ratio, c / a, and I (003) / I (104)When the above ranges are respectively set, the layered structure can be stabilized, the lattice oxygen can be stabilized, and the rapid insertion and removal of lithium ions can be achieved, so that the lithium ions of the positive electrode active material can be smoothly transferred during the charge and discharge process, effectively improving the initial coulombic efficiency and capacity of the lithium ion battery including the positive electrode active material. If the lithium nickel mixing rate is lower than 0.009, or c / a is lower than 4.8, or I (003) / I (104) When it is lower than 1.8, the capacity is low and the cycle performance is reduced; if the lithium nickel mixing rate is higher than 0.015 capacity, or c / a is higher than 5.2, or I (003) / I (104) When it is higher than 2.4, the structural stability is poor and the electrochemical performance decreases.

[0048] This application does not limit the lithium nickel mixing rate, c / a and I of the high nickel positive electrode active material. (003) / I (104) For example, the amount of each raw material added during the preparation process and the process parameters during the preparation process can be controlled to make the lithium nickel mixing rate, c / a and I (003) / I (104) is within the above range.

[0049] In a specific embodiment, the high nickel positive electrode active material includes a core layer and a coating layer covering at least a portion of the surface of the core layer; the core layer includes a first core layer and a second core layer covering at least a portion of the surface of the first core layer; the first core layer has a chemical composition of Formula 2, the second core layer has a chemical composition of Formula 3, and the coating layer has a chemical composition of Formula 4, Li d Ni e Mn f Co g X 1 h O2 Formula 2 LiX 2 O2 Formula 3 LiX 3 O2 Formula 4

[0050] In formula 2, 0.95≤d≤1.05, 0.9≤e≤0.98, e+f+g=1, 0<h≤0.016, X 1 including at least two of Zr, Ti, W, B, Sn, Ta, and Ce;

[0051] In formula 3, X 2 Including at least one of Zr, Ti, W, B, Sn, Ta, Al, Mo, and Co;

[0052] In formula 4, X 3 Includes at least one of W, Al, B, and Co.

[0053] When the high-nickel positive electrode active material comprises the aforementioned structure, and the first inner core layer, second inner core layer, and coating layer have the aforementioned chemical composition, not only can the lithium-ion battery comprising the positive electrode active material exhibit a high capacity and initial coulombic efficiency, but the second inner core layer and coating layer can also provide physical isolation. This isolation has two main aspects: first, it can isolate the electrolyte from the first inner core layer, preventing side reactions between the electrolyte and the first inner core layer during charge and discharge; second, it can prevent the release of lattice oxygen in the positive electrode active material as oxygen during charge and discharge, which reacts with the electrolyte and causes capacity fading and decreased cycle performance.

[0054] In one specific embodiment, the first inner core layer further comprises the element F; the mass percentage of the element F in the first inner core layer is 0.01 to 0.045 wt%. When the first inner core layer includes the element F, the F can replace some of the oxygen in the first inner core layer, forming F-Ni, F-Co, and F-Mn bonds with greater bond energy, thereby reducing the content of unstable lattice oxygen in the first inner core layer, thereby inhibiting the dissolution of metal ions Ni, Co, and Mn, and improving the battery capacity and lifespan. Furthermore, the presence of F can increase the energy barrier for lithium-nickel diffusion, further limiting the occurrence of lithium-nickel mixing. When the mass percentage of the element F is within the above range, the content of unstable lattice oxygen in the first inner core layer can be further reduced, thereby further improving the battery capacity and lifespan.

[0055] Illustratively, the mass percentage of the F element in the first inner core layer is 0.01wt%, 0.015wt%, 0.02wt%, 0.025wt%, 0.03wt%, 0.035wt%, 0.04wt% or 0.045wt%, or a range consisting of any two of these values.

[0056] Specifically, the mass percentage of the F element in the first inner core layer can be tested by an inductively coupled plasma emission spectrometer (ICP).

[0057] In one embodiment, the high-nickel cathode active material includes secondary particles composed of primary particles; the primary particles have a median particle size of 0.2 to 1 μm, and the median particle size of the high-nickel cathode active material is 0.7 to 1.5 μm. Within this range, the capacity of the high-nickel cathode active material can be further increased.

[0058] Illustratively, the median particle size of the primary particles is 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm, or a range consisting of any two of these values.

[0059] Illustratively, the median particle size of the high nickel positive electrode active material is 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, or a range consisting of any two of these values.

[0060] The median particle size of the high-nickel positive electrode active material in the present application can be obtained by laser particle size analyzer testing, and the median particle size of the primary particles in the high-nickel positive electrode active material can be obtained by scanning electron microscopy (SEM) testing and analyzing the SEM images obtained by the test with image processing software.

[0061] In one embodiment, the specific surface area of ​​the high nickel positive electrode active material is 0.9 to 5 m 2 / g. Within this range, the specific surface area of ​​the positive electrode active material is high, and the surface area available for lithium ion embedding is correspondingly large, which can effectively improve the electrode reaction activity and make the battery have a higher capacity; at the same time, the specific surface area will not be too large, which can ensure that the lithium-ion battery has good cycle performance.

[0062] For example, the specific surface area of ​​the high nickel positive electrode active material is 0.9 m 2 / g、1m 2 / g, 1.5m 2 / g, 2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g or 5m 2 / g, or a range consisting of any two values ​​therein.

[0063] The specific surface area of ​​the high nickel positive electrode active material in the present application can be obtained by gas adsorption method (BET method).

[0064] In one embodiment, the powder compaction density of the high nickel positive electrode active material is 3.1 to 3.4 g / cm 3 Within this range, the lithium-ion battery including the positive electrode active material can have a higher capacity while maximizing the capacity performance of the material.

[0065] For example, the powder compaction density of the high nickel positive electrode active material is 3.1 g / cm 3 、3.15g / cm 3 、3.2g / cm 3 、3.25g / cm 3 , 3.3g / cm 3 、3.35g / cm 3 or 3.4g / cm 3, or a range consisting of any two values.

[0066] The powder compaction density of the high nickel positive electrode active material in the present application can be obtained by a powder compaction density tester; specifically, the sample is dried to remove moisture; a certain mass of the dried sample is weighed, a suitable cylindrical mold is selected, the sample is placed in the mold, and the pressure is maintained at 2.5T for 10s to obtain a compact; the diameter D and height H of the compact are measured, and the compact volume V can be calculated based on D and H. The powder compaction density ρ (g / cm 3 )=m / V.

[0067] A second aspect of the present application provides a method for preparing the high-nickel positive electrode active material of the first aspect, comprising the following steps:

[0068] (1) Ni x Co y Mn z (OH)2 is calcined at 400-600°C for 1-5 hours, and then ground and crushed to obtain a first product having a median particle size D50 < 0.8 μm, wherein 0.90 ≤ x ≤ 0.98, and x + y + z = 1;

[0069] (2) mixing the first product, a lithium source, and a dopant to obtain a first mixed raw material, and performing a first sintering in an oxygen atmosphere at a sintering temperature of 600 to 850° C. and a sintering time of 15 to 20 hours to obtain a second product; wherein the molar ratio of lithium in the lithium source to the first product is 0.95 to 1.05, and the mass ratio of the dopant to the theoretical generated mass of the high-nickel positive electrode active material is (0.1 to 10):1000;

[0070] (3) mixing the second product and the first coating agent and performing a second sintering in an oxygen atmosphere at a sintering temperature of 500 to 600° C. for 8 to 12 hours to obtain a third product;

[0071] (4) The third product and the second coating agent are mixed and subjected to a third sintering under a protective atmosphere at a sintering temperature of 300-400° C. for 6-8 h to obtain a high-nickel positive electrode active material.

[0072] Specifically, in step (1), the chemical composition Ni x Co y Mn zThe high-nickel cathode material precursor of (OH)2 is calcined at 400-600°C for 1-5 hours to obtain a calcined product, wherein 0.90≤x≤0.98, x+y+z=1; the calcined product is then ground and crushed to obtain a first product with a median particle size D50 <0.8μm. In this process, the high-nickel cathode material precursor is pre-calcined, ground, and crushed, which helps to produce a small-particle high-nickel cathode active material, effectively improving the capacity of the cathode active material.

[0073] Illustratively, the calcination temperature is 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, or a range consisting of any two values ​​therein; the calcination time is 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, or a range consisting of any two values ​​therein.

[0074] The present application does not specifically limit the source of the high nickel cathode material precursor. For example, a commercial product or a product prepared by a conventional preparation method well known to those skilled in the art can be used. It is only necessary to make the chemical composition of the high nickel cathode material precursor meet the requirements of Ni x Co y Mn z (OH)2(0.90≤x≤0.98, x+y+z=1) can be used.

[0075] This application does not specifically limit the grinding method and crushing method. For example, the grinding can be carried out by at least one of a mechanical grinder, a universal grinder, and a vacuum ball mill, and the crushing can be carried out by at least one of a jet grinder and a universal grinder. It is only necessary to make the median particle size D50 of the first product less than 0.8 μm.

[0076] In step (2), the first product prepared in step (1), a lithium source and a dopant are mixed to obtain a first mixed raw material, wherein the molar ratio of lithium in the lithium source to the first product is 0.95-1.05, and the mass ratio of the dopant to the theoretical generated mass of the high-nickel positive electrode active material is (0.1-10):1000; the first mixed raw material is subjected to a first sintering in an oxygen atmosphere at a sintering temperature of 600-850°C and a sintering time of 15-20h to obtain a sintered product, which is then cooled, crushed and sieved through a mesh to obtain a second product.

[0077] Illustratively, the molar ratio of lithium in the lithium source to the first product is 0.95, 0.97, 0.99, 1.01, 1.03 or 1.05, or a range consisting of any two values ​​therein.

[0078] Illustratively, the mass ratio of the dopant to the theoretical generated mass of the high nickel positive electrode active material is 0.1:1000, 1:1000, 2:1000, 3:1000, 4:1000, 5:1000, 6:1000, 7:1000, 8:1000, 9:1000 or 10:1000, or a range consisting of any two values ​​therein.

[0079] Illustratively, the temperature of the first sintering is 600°C, 650°C, 700°C, 750°C, 800°C or 850°C, or a range consisting of any two of these values; the sintering time is 15h, 16h, 17h, 18h, 19h or 20h, or a range consisting of any two of these values.

[0080] The theoretical generated mass of 1 mol of high nickel positive electrode active material in this application is calculated by formula 5: The theoretical generated mass of 1 mol of high nickel positive electrode active material (g) = a×M1+b×M2+m×M3+n×M4+2×M5 Formula 5

[0081] In formula 5, M1 is the molar mass of lithium, M2 is the molar mass of nickel, M3 is the molar mass of manganese, M4 is the molar mass of cobalt, and M5 is the molar mass of oxygen. The unit of molar mass is g / mol.

[0082] The lithium source in this application refers to a raw material that provides lithium, and the dopant refers to a compound comprising at least two of Zr, Ti, W, B, Sn, Ta, and Ce. As long as the target element is contained, it falls within the definition of this application. For example, the lithium source can be selected from at least one of lithium carbonate, lithium sulfate, lithium nitrate, and lithium hydroxide, and the dopant includes at least two of cerium fluoride, tantalum oxide, zirconium oxide, titanium oxide, tungsten oxide, boron oxide, and tin oxide.

[0083] This application does not specifically limit the cooling method, crushing method, and screen mesh size. For example, the cooling method can be any one of natural cooling and circulating water cooling, the crushing method can be at least one of a mechanical crusher and an air flow crusher, and the screen mesh size can be any one of 400 mesh, 350 mesh, and 325 mesh.

[0084] During the first sintering process, X (at least two of Zr, Ti, W, B, Sn, Ta, and Ce) in the dopant will replace part of Ni, Co, and Mn and combine with O to form XO bonds with larger bond energy, which can inhibit the overflow of unstable lattice oxygen and improve the cycle performance. At the same time, it can also inhibit the growth of primary particles and effectively increase the specific surface area and powder compaction density of the positive electrode active material.

[0085] In step (3), the second product prepared in step (2) is mixed with the first coating agent and subjected to a second sintering in an oxygen atmosphere at a sintering temperature of 500-600° C. for 8-12 hours to obtain a sintered product, which is then cooled, crushed, and sieved to obtain a third product.

[0086] Illustratively, the sintering temperature of the second sintering is 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, or a range consisting of any two of these values; the sintering time is 8h, 9h, 10h, 11h, 12h, or a range consisting of any two of these values.

[0087] The first coating agent in this application refers to a compound including at least one of Zr, Ti, W, B, Sn, Ta, Al, Mo, and Co. As long as the target element is contained, it falls within the definition of this application. Exemplarily, the first coating agent includes at least one of tin oxide, titanium oxide, tungsten oxide, tantalum oxide, molybdenum oxide, zirconium oxide, boron oxide, aluminum oxide, and cobalt oxide.

[0088] The present application does not impose any specific limitation on the molar ratio between the second product and the first coating agent. When two or more first coating agents are included, the present application does not impose any specific limitation on the molar ratio between the first coating agents. It is only necessary that the chemical composition of the prepared high-nickel positive electrode active material satisfies Formula 1.

[0089] The present application does not make any specific limitation on the methods of cooling, crushing and screening. For example, they may be consistent with the limitations in the above step (2) and will not be described in detail here.

[0090] During the second sintering process, the first coating agent reacts with LiOH and LiCO3 on the surface of the first core layer to generate metal lithium compounds. The second core layer formed on the surface of the first core layer helps to reduce the nickel-lithium mixing rate and make the c / a and I (003) / I (104) Within the above-mentioned limits, higher capacity and initial efficiency are guaranteed.

[0091] In step (4), the third product prepared in step (3) is mixed with the second coating agent and subjected to a third sintering in an oxygen atmosphere at a sintering temperature of 300 to 400° C. for 6 to 8 hours to obtain a sintered product, which is then cooled, crushed, and sieved through a mesh to obtain a high-nickel positive electrode active material.

[0092] Illustratively, the temperature of the third sintering is 300°C, 320°C, 340°C, 360°C, 380°C or 400°C, or a range consisting of any two of these values; the sintering time is 6h, 6.5h, 7h, 7.5h or 8h, or a range consisting of any two of these values.

[0093] The second coating agent in the present application refers to a compound including at least one of W, Al, B, and Co. For example, the second coating agent includes at least one of boric acid, boron oxide, aluminum oxide, tungsten oxide, and cobalt oxide.

[0094] The present application does not impose any specific restrictions on the molar ratio between the third product and the second coating agent. When two or more second coating agents are included, the present application does not impose any specific restrictions on the molar ratio between the second coating agents. It is only necessary that the chemical composition of the prepared high-nickel positive electrode active material satisfies Formula 1.

[0095] During the third sintering process, the second coating agent is in a molten state at 300-400°C, and can bring the unreacted first coating agent in the second sintering process to the blank part of the surface of the first inner core layer, so that the first coating agent continues to react with the unreacted LiOH and LiCO3 in the blank part to form a more uniform second inner core layer; at the same time, the second coating agent also reacts with the unreacted LiOH and LiCO3 in the blank part of the surface of the first inner core layer to form a uniform coating layer.

[0096] The preparation method of the high nickel positive electrode active material of the present application comprises the following steps: calcining, crushing and grinding the high nickel positive electrode material precursor in advance; and then adding a dopant, a first coating agent and a second coating agent in the first sintering, the second sintering and the third sintering processes respectively. At the same time, by controlling the preparation process parameters, the high nickel positive electrode active material finally prepared has the chemical composition of formula 1, and has a low lithium nickel mixing rate, a high c / a value and I (003) / I (104) value, thereby having a stable layered structure, so that the lithium ion battery including the high nickel positive electrode active material has a higher capacity and first coulombic efficiency.

[0097] In addition, the above preparation method can also reduce the content of residual lithium (LiOH and LiCO3) on the surface of high-nickel positive electrode active materials, avoid the high alkalinity of the material caused by residual lithium, and then lead to the formation of jelly-like gel during the preparation of the slurry, affecting the processing performance of the material; at the same time, it can also avoid the occurrence of side reactions between residual lithium and the electrolyte, and improve the cycle performance and capacity of the battery.

[0098] In a specific embodiment, the first mixed raw material also includes a fluorine source; the mass ratio of the fluorine source to the theoretical generated mass of the high-nickel positive electrode active material is (1 to 10): 10000. When the fluorine source is added to the first mixed raw material, the F in the fluorine source can replace part of the O in the first inner core layer and combine with Ni, Co, and Mn to form F-Ni bonds, F-Co bonds, and F-Mn bonds with larger bond energy, which can not only reduce the content of unstable lattice oxygen in the first inner core layer, but also inhibit the dissolution of metal ions Ni, Co, and Mn, effectively improving the capacity and life of the battery; when the mass ratio of the fluorine source to the theoretical generated mass of the high-nickel positive electrode active material is within the above range, the content of unstable lattice oxygen can be further reduced, and the inhibitory effect on the dissolution of metal ions Ni, Co, and Mn can be improved, so that the lithium-ion battery has higher capacity and cycle performance.

[0099] Illustratively, the mass ratio of the fluorine source to the theoretical generated mass of the high-nickel positive electrode active material is 1:1000, 2:1000, 3:1000, 4:1000, 5:1000, 6:1000, 7:1000, 8:1000, 9:1000 or 10:1000, or a range consisting of any two values ​​therein.

[0100] The fluorine source in this application refers to a raw material that provides fluorine. As long as it contains the target element, it falls within the scope of this application. For example, the fluorine source may include at least one of cerium fluoride and aluminum fluoride. It should be noted that when the raw material includes two or more of the target elements at the same time, the raw material can be understood as an elemental source of two target elements. For example, when the raw material is cerium fluoride, it acts as both a fluorine source and a cerium source, and the cerium source can be used as a dopant.

[0101] In one embodiment, the heating rate during the first sintering process is 1-4°C / min. Within this range, the lithium-nickel mixing ratio is reduced, and the nickel-lithium mixing ratio of the positive electrode active material is between 0.009 and 0.015, thereby improving the initial efficiency and capacity of the positive electrode active material.

[0102] Illustratively, the heating rate during the first sintering process is 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min or 4°C / min, or a range consisting of any two of these values.

[0103] In one embodiment, the heating rate during the second sintering process is 1-3°C / min. Within this range, it is beneficial to reduce the lithium-nickel mixing rate and control the morphology of the single crystal positive electrode active material, so that the positive electrode active material has a higher capacity.

[0104] Illustratively, the heating rate during the second sintering process is 1° C. / min, 1.5° C. / min, 2° C. / min, 2.5° C. / min, or 3° C. / min, or a range consisting of any two of these values.

[0105] In one embodiment, the heating rate during the third sintering process is 1-3°C / min. Within this range, the lithium-nickel mixing rate can be further reduced and the morphology of the single-crystal-like positive electrode active material can be regulated, thereby further improving the capacity of the positive electrode active material.

[0106] Illustratively, the heating rate in the third sintering process is 1° C. / min, 1.5° C. / min, 2° C. / min, 2.5° C. / min or 3° C. / min, or a range consisting of any two of these values.

[0107] The third aspect of the present application provides a positive electrode sheet. Since the positive electrode sheet includes the high-nickel positive electrode active material of the first aspect, or includes the high-nickel positive electrode active material prepared by the preparation method of the high-nickel positive electrode active material of the second aspect, the positive electrode sheet is applied to a lithium-ion battery to effectively improve the first coulombic efficiency and capacity of the battery.

[0108] In a fourth aspect, the present application provides a lithium-ion battery. Since the lithium-ion battery includes the high-nickel positive electrode active material of the first aspect, or includes the high-nickel positive electrode active material prepared by the preparation method of the high-nickel positive electrode active material of the second aspect, or the positive electrode sheet of the third aspect, the battery has a high first coulombic efficiency and capacity.

[0109] Hereinafter, the high nickel positive electrode active material of the present application will be described in detail through specific examples.

[0110] Example 1

[0111] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0112] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 725 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0113] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0114] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0115] Example 2

[0116] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.5 μm;

[0117] (2) 3 kg of the first product was mixed with lithium hydroxide, 3 g of tin oxide, and 2 g of tantalum oxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 1.58:1000. The temperature was raised from room temperature to 725°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0118] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0119] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Sn 0.0006 Ta 0.0003 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Sn 0.0006 Ta 0.0003 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0120] Example 3

[0121] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.7 μm;

[0122] (2) 3 kg of the first product was mixed with lithium hydroxide, 2 g of boron oxide and 2 g of cerium fluoride in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 1.26:1000, and the mass ratio of the fluorine source to the theoretical mass of the high-nickel positive electrode active material was 6.31:10000; the temperature was raised from room temperature to 725°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product;

[0123] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0124] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Ce 0.0003 B 0.01 F 0.0009 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Ce 0.0003 B 0.002 F 0.0009 O2, the chemical composition of the second inner core layer is LiCoO2, the chemical composition of the coating layer is LiBO2, and the mass percentage of F element in the first inner core layer is 0.017wt%.

[0125] Example 4

[0126] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.66 μm;

[0127] (2) 3 kg of the first product was mixed with lithium hydroxide, 1 g of aluminum fluoride and 2 g of tantalum oxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 0.95:1000, and the mass ratio of the fluorine source to the theoretical mass of the high-nickel positive electrode active material was 3.15:10000; the temperature was raised from room temperature to 725°C at 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product;

[0128] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0129] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Al 0.0003 Ta 0.0003 F 0.0009 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Al 0.0003 Ta 0.0003 F 0.0009 O2, the chemical composition of the second inner core layer is LiCoO2, the chemical composition of the coating layer is LiBO2, and the mass percentage of F element in the first inner core layer is 0.017wt%.

[0130] Example 5

[0131] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0132] (2) 3 kg of the first product was mixed with lithium hydroxide, 6.1 g of zirconium oxide, 3.81 g of yttrium oxide and 2.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 3.76:1000. The temperature was raised from room temperature to 725 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0133] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0134] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.001 Ti 0.0008 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.001 Ti 0.0008 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0135] Example 6

[0136] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0137] (2) 3 kg of the first product was mixed with lithium hydroxide, 7.6 g of zirconium oxide, 4.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.24:1000. The temperature was raised from room temperature to 725°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0138] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0139] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.002 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.002 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0140] Example 7

[0141] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0142] (2) 3 kg of the first product was mixed with lithium hydroxide, 6.8 g of zirconium oxide, 3.21 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 3.48:1000. The temperature was raised from room temperature to 725 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0143] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0144] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0145] Example 8

[0146] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0147] (2) 3 kg of the first product was mixed with lithium hydroxide, 7.2 g of zirconium oxide, 2.81 g of yttrium oxide and 0.86 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 3.43:1000. The temperature was raised from room temperature to 725 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0148] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0149] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0003 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0003 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0150] Example 9

[0151] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0152] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide, 2 g of cerium fluoride and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.71:1000, and the mass ratio of the fluorine source to the theoretical mass of the high-nickel positive electrode active material was 6.31:10000; the temperature was raised from room temperature to 725°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product;

[0153] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0154] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 Ce 0.0003 F 0.0009 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 Ce 0.0003 F 0.0009 O2, the chemical composition of the second inner core layer is LiCoO2, the chemical composition of the coating layer is LiBO2, and the mass percentage of F element in the first inner core layer is 0.017wt%.

[0155] Example 10

[0156] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0157] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide, 10 g of cerium fluoride and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 7.23:1000, and the mass ratio of the fluorine source to the theoretical mass of the high-nickel positive electrode active material was 31.54:10000; the temperature was raised from room temperature to 725°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product;

[0158] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0159] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 Ce 0.001 F 0.003 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 Ce 0.001 F 0.003 O2, the chemical composition of the second inner core layer is LiCoO2, the chemical composition of the coating layer is LiBO2, and the mass percentage of F element in the first inner core layer is 0.058wt%.

[0160] Example 11

[0161] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0162] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 700 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0163] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0164] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0165] Example 12

[0166] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0167] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 825°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0168] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0169] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0170] Example 13

[0171] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0172] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 850°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0173] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0174] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0175] Example 14

[0176] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0177] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide, 4 g of cerium fluoride and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 5.34:1000, and the mass ratio of the fluorine source to the theoretical mass of the high-nickel positive electrode active material was 12.61:10000; the temperature was raised from room temperature to 725°C at a rate of 2°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product;

[0178] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0179] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 Ce 0.0005 F 0.0015 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 Ce 0.0005 F 0.0015 O2, the chemical composition of the second inner core layer is LiCoO2, the chemical composition of the coating layer is LiBO2, and the mass percentage of F element in the first inner core layer is 0.02wt%.

[0180] Example 15

[0181] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0182] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 725°C at a rate of 7°C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0183] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0184] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0185] Example 16

[0186] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0187] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 725 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0188] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at 8° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0189] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 2 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0190] Example 17

[0191] (1) Ni 0.96 Co 0.03 Mn 0.01 (OH)2 was calcined at 500 °C for 5 h and mechanically crushed to obtain the first product with a median particle size D50 of 0.6 μm;

[0192] (2) 3 kg of the first product was mixed with lithium hydroxide, 8.1 g of zirconium oxide, 3.81 g of yttrium oxide and 1.02 g of titanium dioxide in a high-speed mixer to obtain a first mixed material, wherein the molar ratio of the lithium source to the first product was 1.04, and the mass ratio of the dopant to the theoretical mass of the high-nickel positive electrode active material was 4.08:1000. The temperature was raised from room temperature to 725 ° C at a rate of 2 ° C / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 hours. After natural cooling, the mixture was crushed and sieved to obtain a second product.

[0193] (3) 3 kg of the second product and 9.5 g of cobalt oxyhydroxide were mixed uniformly in a high-speed mixer, and the temperature was raised from room temperature to 600° C. at a rate of 2° C. / min in an oxygen atmosphere, and the mixture was kept warm and sintered for 10 h. After natural cooling, the mixture was crushed and sieved to obtain a third product;

[0194] (4) 3 kg of the third product and 17.1 g of boric acid were mixed evenly in a high-speed mixer, and the temperature was raised from room temperature to 330 ° C at 9 ° C / min in an oxygen atmosphere, and the heat preservation sintering was carried out for 8 hours. The third sintering was carried out in an oxygen atmosphere to obtain a sintered product, which was naturally cooled, crushed and sieved to obtain the high-nickel positive electrode active material of this embodiment. The chemical composition of the positive electrode active material was Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0004 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0195] Comparative Example 1

[0196] The preparation method of the high-nickel positive electrode active material in this comparative example is basically the same as that in Example 1, except that in step (1), the sintering temperature is 650° C. and the heat preservation sintering time is 6 h.

[0197] According to ICP test, the chemical composition of the high nickel positive electrode active material prepared in this comparative example is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0198] Comparative Example 2

[0199] The preparation method of the high-nickel positive electrode active material in this comparative example is basically the same as that in Example 1, except that in step (1), the median particle size of the first product is 1.1 μm.

[0200] According to ICP test, the chemical composition of the high nickel positive electrode active material prepared in this comparative example is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 O2, the chemical composition of the second inner core layer is LiNiO2, and the chemical composition of the coating layer is LiBO2.

[0201] Comparative Example 3

[0202] The preparation method of the high-nickel positive electrode active material in this comparative example is basically the same as that in Example 1, except that in step (2), the sintering temperature is 580° C. and the sintering time is 13 h.

[0203] According to ICP test, the chemical composition of the high nickel positive electrode active material prepared in this comparative example is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0204] Comparative Example 4

[0205] The preparation method of the high-nickel positive electrode active material in this comparative example is basically the same as that in Example 1, except that, in step (2), the amount of zirconium oxide added as the dopant is 22.37 g, the amount of yttrium oxide added is 10.12 g, and the amount of titanium dioxide added is 5.54 g. The mass ratio of the dopant to the theoretical generated mass of the high-nickel positive electrode active material is 12:1000.

[0206] According to ICP test, the chemical composition of the high nickel positive electrode active material prepared in this comparative example is Li 1.04 Ni0.96 Co 0.03 Mn 0.01 Zr 0.005 Ti 0.002 Y 0.003 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.005 Ti 0.002 Y 0.003 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0207] Comparative Example 5

[0208] The preparation method of the high-nickel positive electrode active material in this comparative example is basically the same as that in Example 1, except that in step (3), the sintering temperature is 400° C. and the heat preservation sintering time is 5 h.

[0209] According to ICP test, the chemical composition of the high nickel positive electrode active material prepared in this comparative example is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 B 0.008 O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0210] Comparative Example 6

[0211] The preparation method of the high-nickel positive electrode active material in this comparative example is basically the same as that in Example 1, except that in step (4), the sintering temperature is 500° C. and the heat preservation sintering time is 15 h.

[0212] According to ICP test, the chemical composition of the high nickel positive electrode active material prepared in this comparative example is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 B 0.008O2, where the chemical composition of the first inner core layer is Li 1.04 Ni 0.96 Co 0.03 Mn 0.01 Zr 0.002 Ti 0.0005 Y 0.001 O2, the chemical composition of the second inner core layer is LiCoO2, and the chemical composition of the coating layer is LiBO2.

[0213] Test example

[0214] 1. The high-nickel positive electrode active materials prepared in Examples 1 to 4 were subjected to SEM testing, and the test results are shown in Figures 1 to 4; the high-nickel positive electrode active materials prepared in the above examples and comparative examples were subjected to XRD testing, and the test results are shown in Table 1; the high-nickel positive electrode active materials prepared in the above examples and comparative examples were subjected to ICP testing to obtain the molar amount of Li / (Ni+Co+Mn) molar amount; the high-nickel positive electrode active materials prepared in the above examples and comparative examples were subjected to physical and chemical property tests to obtain the median particle size D50 of the primary particles in the high-nickel positive electrode active material and the median particle size D50, specific surface area, and powder compaction density of the high-nickel positive electrode active material. The test results are shown in Table 1.

[0215] Figures 1 to 4 are SEM images of the high-nickel positive electrode active materials prepared in Example 1, Example 2, Example 3, and Example 4, respectively. It can be seen from Figures 1 to 4 that the prepared high-nickel positive electrode active materials have a small particle size and a rough surface, which helps to improve the specific capacity of the positive electrode active materials.

[0216] 2. The high-nickel positive electrode active materials prepared in the above examples and comparative examples are applied to lithium-ion batteries. The specific steps are as follows:

[0217] The high nickel positive electrode active material prepared in the above examples and comparative examples was mixed with conductive carbon, polyvinylidene fluoride, and N-methylpyrrolidone in a mass ratio of 85:10:5, ensuring a fineness of 10 μm and a viscosity of 5000 mPa·s to obtain a positive electrode active layer slurry; the positive electrode active layer slurry was passed through a 200-mesh sieve and then coated on the surface of the positive electrode current collector aluminum foil. The surface density of the coating was 370 g / m 2 , dried at 120°C for 80 min, rolled and sliced ​​to obtain a positive electrode sheet with a compaction density of 3.45 g / cm 3 ; The positive electrode sheet is assembled with a lithium sheet, a cellulose separator and a conventional lithium hexafluorophosphate electrolyte into a button battery, wherein the electrolyte includes ethylene carbonate, ethyl methyl carbonate and lithium hexafluorophosphate, the volume ratio of ethylene carbonate and ethyl methyl carbonate (EMC) is 3:7, and the mass percentage of lithium hexafluorophosphate in the electrolyte is 12.5wt%.

[0218] The button cells including the high nickel positive active materials of the above examples and comparative examples were tested for capacity and initial coulombic efficiency:

[0219] (1) Capacity

[0220] Charge at a constant current rate of 0.2C to a voltage of 4.25V, then charge at a constant voltage under the cut-off voltage condition until the current is less than 0.05C. The charging capacity at this time is recorded as the first cycle charging capacity. After that, let it stand for 5 minutes, and then discharge at a constant current rate of 0.2C to a voltage of 2.5V. The discharge capacity this time is recorded as the first cycle discharge capacity of the battery, that is, the initial capacity. The test results are shown in Table 2.

[0221] (2) First Coulombic efficiency

[0222] At 25°C, the charge and discharge voltage window is 2.5-4.3V. Charge at 0.2C and discharge at 0.2C, and obtain the 0.2C discharge gram capacity C1 and the 0.2C charge gram capacity C2. The first coulombic efficiency is calculated by formula 5: First coulombic efficiency (%) = C1 / C2 Formula 5;

[0223] The test results are shown in Table 2.

[0224] (3) Residual lithium test

[0225] Weigh 30g of the high-nickel positive electrode active material prepared in the above embodiments and comparative examples respectively for use, place the weighed sample in a 100mL beaker, add 50mL of deionized water, place the magnetic beads in the beaker and seal it with plastic wrap, then place the beaker on a magnetic stirrer and stir for about 25 minutes before removing it; let it stand for 5 minutes, filter it with a glass funnel, and the filtered clear liquid is the solution to be tested; the content of residual alkali (Li2CO3 and LiOH) in the solution to be tested is tested by an automatic potentiometric titrator, 0.1M HCl is used as the titrant, and the titration rate is 0.5mL / min, and the end points V1 and V2 are obtained. The content of LiOH and Li2CO3 is calculated by Formula 6 and Formula 7: Li2CO3 (ppm) = 0.001×73.89 / (V2-V1) Formula 6 LiOH (ppm) = 0.001×23.95 / (2V1-V2) Formula 7

[0226] The calculation results are shown in Table 2.

[0227] Table 1

[0228] Table 2

[0229] From Table 1 and Table 2, we can see that:

[0230] Compared with the positive electrode active materials of Comparative Examples 1 to Comparative Examples 6, the lithium nickel mixing rate of the positive electrode active materials in Examples 1 to 17 is lower, and the c / a and I(003) / I(104) are higher. Therefore, applying the positive electrode active materials in Examples 1 to 17 to batteries can significantly improve the capacity and first coulombic efficiency of the batteries. The 0.2C charging gram capacity of the batteries in Examples 1 to 17 can reach up to 252.7 mAh / g, the 0.2C discharge gram capacity can reach up to 239.1 mAh / g, and the first coulombic efficiency can reach up to 96.91%, which are significantly higher than those of Comparative Examples 1 to 6. It can be seen that the positive electrode active materials of the present application can significantly improve the capacity and first coulombic efficiency of the battery.

[0231] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A high nickel positive electrode active material, wherein: Comprising the chemical composition shown in Formula 1, Li a Ni b Mn m Co n X c O2 Formula 1 In formula 1, 0.95≤a≤1.05, 0.90≤b≤0.98, 0<c≤0.016, b+m+n=1, and X includes at least two of Zr, Ti, W, B, Sn, Ta, Al, Mo, Co, and Ce; The lithium-nickel mixing ratio of the high-nickel positive electrode active material is 0.009 to 0.015; In the X-ray diffraction pattern of the high-nickel positive electrode active material, c / a is 4.8 to 5.2; In the X-ray diffraction pattern of the high nickel positive electrode active material, the peak areas of the diffraction peaks at 2θ of 18.8±0.5° and 44.3±0.5° are respectively 1 (003) , I (104) , and I (003) / I (104) It is 1.8 to 2.

4.

2. The high nickel positive electrode active material according to claim 1, wherein The high nickel positive electrode active material includes a core layer and a coating layer covering at least a portion of the surface of the core layer; the core layer includes a first core layer and a second core layer covering at least a portion of the surface of the first core layer; the first core layer has a chemical composition of Formula 2, the second core layer has a chemical composition of Formula 3, and the coating layer has a chemical composition of Formula 4, Li d Ni e Mn f Co g X 1 h O2 Formula 2 LiX 2 O2 Formula 3 LiX 3 O2 Formula 4 In formula 2, 0.95≤d≤1.05, 0.9≤e≤0.98, e+f+g=1, 0<h≤0.016, X 1 including at least two of Zr, Ti, W, B, Sn, Ta, and Ce; In formula 3, X 2 Including at least one of Zr, Ti, W, B, Sn, Ta, Al, Mo, and Co; In formula 4, X 3 Includes at least one of W, Al, B, and Co.

3. The high nickel positive electrode active material according to claim 2, wherein The first core layer further comprises F element; the mass percentage of F element in the first core layer is 0.01-0.045 wt %.

4. The high nickel positive electrode active material according to any one of claims 1 to 3, wherein: The high-nickel positive electrode active material includes secondary particles composed of primary particles; the median particle size of the primary particles is 0.2 to 1 μm. 5 . The high-nickel positive electrode active material according to claim 1 , wherein the median particle size of the high-nickel positive electrode active material is 0.7 to 1.5 μm.

6. The high nickel positive electrode active material according to any one of claims 1 to 5, wherein: The specific surface area of ​​the high nickel positive electrode active material is 0.9 to 5 m 2 / g.

7. The high nickel positive electrode active material according to any one of claims 1 to 6, wherein: The powder compaction density of the high nickel positive electrode active material is 3.1 to 3.4 g / cm 3 .

8. A method for preparing the high-nickel positive electrode active material according to any one of claims 1 to 7, wherein: The following steps are involved: (1) Ni x Co y Mn z (OH)2 is calcined at 400-600°C for 1-5 hours, and then ground and crushed to obtain a first product having a median particle size D50 < 0.8 μm, wherein 0.90 ≤ x ≤ 0.98, and x + y + z = 1; (2) mixing the first product, a lithium source, and a dopant to obtain a first mixed raw material, and performing a first sintering in an oxygen atmosphere at a sintering temperature of 600 to 850° C. and a sintering time of 15 to 20 hours to obtain a second product; wherein the molar ratio of lithium in the lithium source to the first product is 0.95 to 1.05, and the mass ratio of the dopant to the theoretical generated mass of the high-nickel positive electrode active material is (0.1 to 10):1000; (3) mixing the second product and the first coating agent and performing a second sintering in an oxygen atmosphere at a sintering temperature of 500 to 600° C. for 8 to 12 hours to obtain a third product; (4) The third product and the second coating agent are mixed and subjected to a third sintering under a protective atmosphere at a sintering temperature of 300 to 400° C. and a sintering time of 6 to 8 hours to obtain the high-nickel positive electrode active material.

9. The method for preparing a high-nickel positive electrode active material according to claim 8, wherein: The first mixed raw material also includes a fluorine source; the mass ratio of the fluorine source to the theoretical generated mass of the high-nickel positive electrode active material is (1-10):10000.

10. The method for preparing a high-nickel positive electrode active material according to claim 8 or 9, wherein: The heating rate during the first sintering process is 1-4°C / min.

11. The method for preparing a high-nickel positive electrode active material according to any one of claims 8 to 10, wherein: The heating rate during the second sintering process is 1-3°C / min.

12. The method for preparing a high-nickel positive electrode active material according to any one of claims 8 to 11, wherein: The heating rate during the third sintering process is 1-3°C / min.

13. A positive electrode sheet, wherein: The positive electrode sheet comprises the high-nickel positive electrode active material according to any one of claims 1 to 7, or comprises the high-nickel positive electrode active material prepared by the method for preparing the high-nickel positive electrode active material according to any one of claims 8 to 12.

14. A lithium ion battery, wherein: The invention comprises the high-nickel positive electrode active material according to any one of claims 1 to 7, or the high-nickel positive electrode active material prepared by the preparation method of the high-nickel positive electrode active material according to any one of claims 8 to 12, or the positive electrode sheet according to claim 13.

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