Positive electrode active material, method for manufacturing the same, positive electrode sheet, battery, and electric device

Abstract

This application discloses a positive electrode active material and its preparation method, a positive electrode sheet, a battery, and an electrical device. The positive electrode active material includes a matrix and a coating material, wherein the coating material includes a compound represented by Formula II: La. α Zr β M γ M' δ O ε Formula II; wherein M includes at least one element selected from Li, Na, Ca, Mg, Ba, and Sr, and M' includes at least one element selected from Al, Ti, Sn, Nb, Ta, W, and Mo, 0 < α ≤ 3, 0 < β ≤ 2, 0 ≤ γ < 0.5, 0 ≤ δ < 0.5, and 5 ≤ ε ≤ 10; in the X-ray diffraction pattern of the coating material, the full width at half maximum (FWHM) of the diffraction peak (222) is FWHM. (222) And satisfy: 0.3≤FWHM (222) ≤0.53. Therefore, the above-mentioned coating material has a low thermal conductivity, which can form a physical barrier on the surface of the multi-electrode material. It can also effectively adsorb the active oxygen released from the high-lithiation matrix material, reduce the side reactions between the matrix and the electrolyte, reduce the heat release peak of the positive electrode active material, and thus improve the thermal stability and cycle stability of the battery, thereby improving the battery's safety performance.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to positive electrode active materials and their preparation methods, positive electrode sheets, batteries, and electrical devices. Background Technology

[0002] As the core material of lithium batteries, the cathode directly determines the battery's performance level. Lithium nickel manganese cobalt oxide cathode active materials (referred to as ternary materials) have higher specific capacity, energy density, and power density, as well as relatively stable performance, making them a popular material for commercial cathodes.

[0003] Currently, the mainstream development direction for ternary materials is high nickel content, single crystallization, and high voltage. However, high-nickel ternary materials exhibit structural instability under high charging cutoff voltages, with the layered structure transforming into a spinel structure. High-nickel ternary materials also suffer from problems such as lithium-nickel mixing, unstable TM (transition metal)-O bonds, and lattice oxygen release during charging and discharging. The main methods to improve the thermal stability of high-nickel ternary materials include single crystallization, bulk element doping, and surface coating modification. While single crystallization and bulk doping improve thermal stability, they often reduce capacity. Surface coating can effectively suppress side reactions between the positive electrode active material and the electrolyte, stabilize the surface structure, suppress irreversible phase transitions, and prevent gas evolution, thereby improving the structural and thermal stability of ternary materials. However, the thermal stability and cycle life of current ternary materials still do not meet the requirements. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] A first aspect of this application provides a positive electrode active material, the positive electrode active material comprising a matrix, the matrix comprising a compound represented by Formula I: Li x (Ni 1-i-j Co i Mn j M'' p O2 Formula I, wherein M'' includes at least one element selected from B, P, Al, Ti, Y, Zr, La, Nb, Ta, W, V, Cr, Mo, and Sb, with 0.9 ≤ x ≤ 1.3, 0.02 ≤ i ≤ 0.2, 0 < j ≤ 0.2, and 0.002 < p ≤ 0.1; a coating material located on at least a portion of the surface of the matrix, the coating material comprising a compound represented by Formula II: La α Zr β M γ M' δ O εFormula II; wherein M includes at least one element selected from Li, Na, Ca, Mg, Ba, and Sr, and M' includes at least one element selected from Al, Ti, Sn, Nb, Ta, W, and Mo, 0 < α ≤ 3, 0 < β ≤ 2, 0 ≤ γ < 0.5, 0 ≤ δ < 0.5, and 5 ≤ ε ≤ 10; in the X-ray diffraction pattern of the coating material, the full width at half maximum (FWHM) of the diffraction peak (222) is FWHM. （222） And satisfy: 0.3≤FWHM （222） ≤0.53. Therefore, the above-mentioned coating material has a low thermal conductivity, which can form a physical barrier on the surface of the multi-electrode material, reduce the side reactions between the matrix and the electrolyte, reduce the heat release peak of the positive electrode active material, and thus improve the thermal stability and cycle stability of the battery, thereby improving the battery's safety performance.

[0006] According to some embodiments of this application, the mass percentage of the coating material is 0.05%-2%, optionally 0.1%-0.5%, based on the total mass of the substrate. This reduces the peak heat release of the positive electrode active material and improves the thermal stability of the battery.

[0007] According to some embodiments of this application, in the X-ray diffraction pattern of the coating material, the ratio of the peak intensity of diffraction peak (222) to the peak intensity of diffraction peak (440) satisfies: 2.8 ≤ I （222） / I （440） ≤3.5. Therefore, the coating material has a high degree of crystallinity and good crystal orientation, exhibiting better oxygen adsorption effect, thereby suppressing the side reactions between the delithiated cathode material and the electrolyte, and improving the electrochemical performance of the cathode material.

[0008] According to some embodiments of this application, the proportion of impurity phase in the crystal structure of the coating material is less than or equal to 2%, and optionally, the proportion of impurity phase in the crystal structure of the coating material is less than or equal to 1.5%. Thus, the coating material has a more stable crystal structure, provides more active sites, and exhibits better electrochemical performance.

[0009] According to some embodiments of this application, the positive electrode active material satisfies at least one of the following conditions: the average particle size D of the matrix 50 The preferred size is 1.2μm-6.2μm, D. 50 The particle size ranges from 2.2 μm to 4.5 μm; the average particle size of the coating material is 10 nm to 100 nm. Therefore, the coating material can provide more chemical reaction sites, accelerate the rate of chemical reactions, and exhibits ionic conductivity and high charge transport efficiency.

[0010] A second aspect of this application provides a method for preparing the positive electrode active material provided in the first aspect of this application, the method comprising: Lanthanum source, zirconium source, M source, M' source, first precipitant, first complexing agent, and first solvent are mixed and subjected to a first co-precipitation, followed by drying to obtain La. α Zr β M γ M' δ Co-precipitation precursor; for the La α Zr β M γ M' δ The co-precipitated precursor is first calcined at 700℃-910℃ to obtain a coating material. A nickel source, cobalt source, manganese source, a second precipitant, a second complexing agent, and a second solvent are mixed and subjected to a second co-precipitation to obtain a multi-element material precursor. The multi-element material precursor, a lithium source, and an M'' source are then mixed and subjected to a second calcination at 650℃-1000℃ to obtain a multi-element material. Finally, the multi-element material and the coating material are mixed and subjected to a third calcination at 600℃-900℃ to obtain the positive electrode active material. This process forms a uniform coating material on the surface of the multi-element material. Because the coating material has low thermal conductivity, it reduces the peak heat release of the positive electrode active material, thereby improving the thermal stability and cycle stability of the battery and enhancing its safety performance. Furthermore, the method for preparing the positive electrode active material proposed in this application is simple, low-cost, and easily scaled up.

[0011] According to some embodiments of this application, the temperature of the third calcination is 650℃-850℃; and / or the time of the third calcination is 4h-48h, optionally 8h-24h.

[0012] According to some embodiments of this application, when the multi-element material and the coating material are mixed, the mass of the coating material is m1, the mass of the multi-element material is m2, and the mass satisfies 0.01%≤m1 / m2≤5%, optionally, 0.1%≤m1 / m2≤2%.

[0013] According to some embodiments of this application, the method satisfies at least one of the following conditions: the heating rate of the first calcination is 0.5℃ / min-10℃ / min, optionally 1℃ / min-5℃ / min; the time of the first calcination is 5h-24h, optionally 8h-18h; the temperature of the second calcination is 750℃-900℃; and the time of the second calcination is 4h-48h, optionally 8h-24h.

[0014] According to some embodiments of this application, the method satisfies at least one of the following conditions: the particle size Dv50 of the multi-element material is 2μm-20μm, optionally 3μm-15μm; the specific surface area of ​​the multi-element material is 0.2m². 2 / g-1.2m 2 / g, optional 0.4m 2 / g-1m 2 / g.

[0015] According to some embodiments of this application, at least one of the following conditions is met: the pH value of the first coprecipitation is 7.5-11.5 and the temperature is 30℃-55℃; the pH value of the second coprecipitation is 10-13 and the temperature is 40℃-80℃.

[0016] The third aspect of this application provides a positive electrode sheet, including the positive active material provided in the first aspect of this application or the positive active material prepared by the method provided in the second aspect of this application.

[0017] The fourth aspect of this application provides a battery, including the positive electrode sheet provided in the third aspect of this application or the positive electrode active material provided in the first aspect of this application.

[0018] The fifth aspect of this application provides an electrical device, including the battery provided in the fourth aspect of this application. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic flowchart of a method for preparing a positive electrode active material according to an embodiment of this application is shown.

[0020] Figure 2 The XRD patterns of the coating materials prepared in Examples 1-3 of this application are shown.

[0021] Figure 3 The image shows an SEM image of the coating material prepared in Example 1 of this application.

[0022] Figure 4 The image shows a SEM image of the positive electrode active material prepared in Example 1 of this application.

[0023] Figure 5 The image shows a SEM image of the positive electrode active material prepared in Comparative Example 1 of this application. Detailed Implementation

[0024] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0025] A first aspect of this application provides a positive electrode active material, the positive electrode active material comprising: The matrix comprises a compound represented by Formula I: Li x (Ni 1-i-j Co i Mn j M'' p O2 formula I, Wherein, M'' includes at least one element selected from B, P, Al, Ti, Y, Zr, La, Nb, Ta, W, V, Cr, Mo, and Sb, and 0.9≤x≤1.3, 0.02≤i≤0.2, 0<j≤0.2, and 0.002<p≤0.1; A coating material, the coating material being located on at least a portion of the surface of the substrate, the coating material comprising a compound represented by Formula II: La α Zr β M γ M' δ O ε Formula II; Wherein, M includes at least one element selected from Li, Na, Ca, Mg, Ba, and Sr, and M' includes at least one element selected from Al, Ti, Sn, Nb, Ta, W, and Mo, 0 < α ≤ 3, 0 < β ≤ 2, 0 ≤ γ < 0.5, 0 ≤ δ < 0.5, and 5 ≤ ε ≤ 10; In the X-ray diffraction pattern of the coating material, the full width at half maximum (FWHM) of the diffraction peak (222) is 1000 m / s. （222） And satisfy: 0.3≤FWHM （222） ≤0.53.

[0026] The positive electrode active material proposed in this application has the following advantages: (1) When the coating material is doped with M element, the phase formation temperature of the coating material can be reduced; when the coating material is doped with M' element, the grain size can be reduced and the full width at half maximum (FWHM) can be increased. （222） This improves the adsorption of reactive oxygen species by the coating material and reduces the thermal conductivity of the coating material.

[0027] (2) By forming the coating material proposed in this application on at least a portion of the surface of the substrate, physical isolation can be formed between the substrate and the electrolyte, reducing the contact between the substrate and the electrolyte, reducing the side reactions between the positive electrode active material and the electrolyte, reducing the consumption of electrolyte, and improving the cycle performance of the battery.

[0028] (3) The coating material has high thermal stability and low thermal conductivity, which can reduce the heat release peak of the positive electrode active material, thereby improving the thermal stability and cycle stability of the battery and improving the safety performance of the battery.

[0029] (4) The oxygen vacancies in the coating material can effectively adsorb the active oxygen in the delithiated positive material, reduce the side reactions between the delithiated matrix material and the electrolyte, and improve the cycle performance of the battery.

[0030] In this application, the X-ray diffraction test method involves using a Rigaku automated X-ray diffractometer for phase and crystal structure analysis. The operating voltage is 40 kV, the operating current is 200 mA, and continuous scanning is employed at a scanning speed of 3° / min, a step size of 0.02°, and a scanning angle of 10°–80°. The full width at half maximum (FWHM) of the material can be calculated using the Rigaku Information Collector tool software. （222） .

[0031] If the half-width at half-maximum (WHM) of the coating material is too small, it indicates that the coating material is too crystallinity and lacks sufficient surface activity; if the WHM of the coating material is too large, the crystal structure of the coating material is not regular enough, which affects the diffusion of ions in the electrode.

[0032] As an example, the FWHM of the coating material （222） It can be 0.3, 0.35, 0.4, 0.45, 0.5, etc., or it can be a range of any of the above values.

[0033] As an example, x can be 0.9, 1, 1.1, 1.2, 1.3, etc., or a range of any of the above values. This increases the specific capacity of the positive electrode active material and improves the energy density of the battery.

[0034] It should be noted that lithium ions are consumed during battery formation and cycling, which may result in the measured lithium content (x) in the positive electrode active material being less than 1. Conversely, if lithium replenishment agents are used on both the positive and negative electrode plates, the measured lithium content (x) in the positive electrode active material may be greater than 1 after the battery undergoes formation and cycling.

[0035] As an example, i can be 0.02, 0.05, 0.1, 0.15, 0.2, etc., or a range of any of the above values. This improves the electronic conductivity of the matrix material, thereby increasing the battery's specific capacity and rate performance.

[0036] As an example, j can be 0.05, 0.1, 0.15, 0.2, etc., or a range of any of the above values. This improves the structural stability of the matrix material and enhances the cycle performance of the battery.

[0037] As an example, p can be 0.005, 0.01, 0.05, 0.1, etc., or a range of any of the above values. This improves the structural stability of the matrix material, especially the structural stability of the matrix material after delithiation, thereby enhancing the cycle performance of the battery.

[0038] As an example, α can be 1, 2, 3, etc., or it can be a range of any of the above values.

[0039] As an example, β can be 0.5, 1, 1.5, 2, etc., or a range of any of the above values.

[0040] As an example, γ can be 0.1, 0.2, 0.3, 0.4, 0.45, etc., or a range of any of the above values.

[0041] As an example, δ can be 0.1, 0.2, 0.3, 0.4, 0.45, etc., or a range of any of the above values.

[0042] As an example, ε can be 5, 6, 7, 8, 9, 10, etc., or a range of any of the above values.

[0043] According to some embodiments of this application, based on the total mass of the substrate, the mass percentage of the coating material can be 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, etc., or a range of any of the above values. Specifically, during the preparation of the positive electrode active material, the content of the coating material on the substrate surface can be controlled by controlling the amount of multi-component materials and the amount of coating material added. If the content of the coating material is too low, the effect on reducing the peak thermal release of the positive electrode active material is not significant. By keeping the content of the coating material within the above range, the peak thermal release of the positive electrode active material can be reduced while increasing the content of the substrate material on the positive electrode sheet, thereby increasing the energy density of the battery.

[0044] According to some specific embodiments of this application, the mass percentage of the coating material is 0.1%-0.5% based on the total mass of the substrate.

[0045] According to some embodiments of this application, in the X-ray diffraction pattern of the coating material, the ratio of the peak intensity of diffraction peak (222) to the peak intensity of diffraction peak (440) satisfies: 2.8 ≤ I （222） / I （440） ≤3.5. For example, it can be 2.8, 3, 3.2, 3.4, 3.5, etc., or any range of the above values. Therefore, the coating material has a high degree of crystallinity and good crystal orientation, exhibiting better oxygen adsorption, thereby suppressing side reactions between the delithiated cathode material and the electrolyte, and improving the electrochemical performance of the cathode material.

[0046] According to some embodiments of this application, the proportion of impurity phase in the crystal structure of the coating material is less than or equal to 2%, for example, it can be 2%, 1.5%, 1%, 0.5%, etc., or it can be any range of the above values. Therefore, the coating material has a more stable crystal structure, provides more active sites, and exhibits better electrochemical performance.

[0047] As an example, the impurity phase in the crystal structure of the coating material refers to ZrO2, and the content of the impurity phase in the coating material can be controlled by controlling the molar ratio of La and Zr elements.

[0048] According to some specific embodiments of this application, the proportion of impurity phase in the crystal structure of the coating material is less than or equal to 1.5%.

[0049] According to some embodiments of this application, the average particle size D of the matrix material 50 The value is 1.2μm-6.2μm, for example, it can be 1.2, 2.2, 3.2, 4.2, 5.2, 6.2, etc., or it can be any range of the above values. According to some specific embodiments of this application, D... 50 The range is 2.2μm-4.5μm.

[0050] According to some embodiments of this application, the average particle size of the coating material is 10nm-100nm. For example, it can be 10nm, 30nm, 50nm, 70nm, 90nm, 100nm, etc. Thus, the coating material can provide more chemical reaction sites, accelerate the rate of chemical reaction, and improve the ionic conductivity and charge transport efficiency of the positive electrode active material.

[0051] In this application, the method for testing the average particle size of the coating material is as follows: the particle size of the coating material on the surface of the matrix material is analyzed using a scanning electron microscope (SEM) at a magnification of 30k, the particle size of 50 coated particles is tested, and the average value is taken as the average particle size of the coating material.

[0052] It should be noted that, during the preparation of the coating material, the average particle size of the coating material can be controlled by controlling the median particle size of the coating material after airflow abrasion.

[0053] A second aspect of this application provides a method for preparing the positive electrode active material provided in the first aspect of this application, the method comprising: Lanthanum source, zirconium source, M source, M' source, first precipitant, first complexing agent, and first solvent are mixed and subjected to a first co-precipitation, followed by drying to obtain La. α Zr β M γ M' δ Co-precipitation precursor; for the Laα Zr β M γ M' δ The co-precipitated precursor is first calcined at a temperature of 600℃-950℃ to obtain a coating material. A nickel source, cobalt source, manganese source, a second precipitant, a second complexing agent, and a second solvent are mixed and subjected to a second co-precipitation to obtain a multi-element material precursor. The multi-element material precursor, a lithium source, and an M'' source are then mixed and subjected to a second calcination at a temperature of 700℃-910℃ to obtain a multi-element material. Finally, the multi-element material and the coating material are mixed and subjected to a third calcination at a temperature of 600℃-900℃ to obtain the positive electrode active material. This process forms a uniform coating material on the surface of the multi-element material. Because the coating material has low thermal conductivity, it reduces the peak heat release of the positive electrode active material, thereby improving the thermal stability and cycle stability of the battery and enhancing its safety performance. Furthermore, the method for preparing the positive electrode active material proposed in this application is simple, low-cost, and easily scaled up.

[0054] The method proposed in this application will be described in detail below, for reference only. Figure 1 The method includes: S10: Lanthanum source, zirconium source, M source, M' source, first precipitant, first complexing agent, and first solvent are mixed and subjected to a first co-precipitation, followed by drying to obtain La. α Zr β M γ M' δ Coprecipitation precursor In this step, lanthanum source, zirconium source, M source, and M' source are prepared into a first mixed solution, and a first complexing agent and a first precipitant are prepared into a first complexing agent solution and a first precipitant solution, respectively. In the presence of the reaction substrate, the first mixed solution, the first precipitant solution, and the first complexing solution are added to the reaction vessel for the first co-precipitation. After the reaction is completed, the mixture is aged, washed, and dried to obtain La. α Zr β M γ M' δ Co-precipitation of precursors.

[0055] According to some embodiments of this application, the lanthanum source includes lanthanum salts, which include at least one of nitrates and lanthanum-containing chlorides.

[0056] According to some embodiments of this application, the concentration of the first mixed solution, calculated by metal element, is 0.5 mol / L-3 mol / L. According to some specific embodiments of this application, the concentration of the first mixed solution is 1 mol / L-2.5 mol / L.

[0057] According to some embodiments of this application, the first precipitant includes at least one of NaOH, KOH, LiOH, Na2CO3, K2CO3, NH4HCO3, and (NH4)2CO3.

[0058] According to some embodiments of this application, the concentration of the first precipitant solution can be 1 mol / L to 10 mol / L.

[0059] According to some embodiments of this application, the first complexing agent includes at least one of ammonia and ethylenediaminetetraacetic acid.

[0060] According to some embodiments of this application, the concentration of the first complexing agent solution is 4 mol / L-13 mol / L.

[0061] According to some embodiments of this application, the pH value of the first coprecipitation reaction solution can be 7.5-11.5, for example, it can be 7.5, 8.5, 9.5, 10.5, 11.5, etc., or it can be any range of the above values.

[0062] According to some embodiments of this application, the temperature of the first coprecipitation reaction solution can be 30℃-55℃, for example, it can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, etc., or it can be any range of the above values.

[0063] According to some embodiments of this application, the stirring speed for the first coprecipitation reaction can be 300 rpm to 800 rpm, and the co-current time can be 5 h to 60 h.

[0064] By conducting the first co-precipitation under the above conditions, the metal elements can be precipitated uniformly.

[0065] According to some embodiments of this application, the aging time can be 0.5h-4h, for example, it can be 0.5h, 1h, 2h, 3h, 4h, etc., or it can be a range of any of the above values.

[0066] According to some embodiments of this application, pure water can be used to wash the precipitate, and the temperature of the pure water can be 50℃-80℃.

[0067] S20: For the La α Zr β M γ M' δ The coprecipitated precursor is subjected to a first calcination at a temperature of 700℃-910℃ to obtain the coating material. In this step, the La is subjected to a dry atmosphere. α Zr β Mγ M' δ The coprecipitated precursor is subjected to a first calcination, sand milling, drying and crushing to obtain the coating material. The temperature of the first calcination can be 700℃-910℃.

[0068] Specifically, the dry atmosphere can be formed by dry air, dry oxygen, etc.

[0069] According to some embodiments of this application, the heating rate of the first calcination is 0.5℃ / min-10℃ / min, for example, it can be 0.5℃ / min, 1℃ / min, 3℃ / min, 5℃ / min, 7℃ / min, 9℃ / min, 10℃ / min, etc., or it can be any range of the above values. According to some specific embodiments of this application, the heating rate of the first calcination is 1℃ / min-5℃ / min.

[0070] According to some embodiments of this application, the temperature of the first calcination can be 700℃, 800℃, 900℃, 910℃, etc., or can be a range of any of the above values.

[0071] According to some embodiments of this application, the first calcination time can be 5h-24h, for example, 5h, 10h, 15h, 20h, 24h, or any range of the above values. According to some specific embodiments of this application, the first calcination time is 8h-18h.

[0072] By keeping the heating rate, temperature, and time of the first calcination within the above range, it helps to reduce the internal stress of the material, obtain a uniform crystal structure, improve the crystallinity of the material, and reduce the agglomeration between particles.

[0073] According to some embodiments of this application, the solvent for milling may include at least one of water, ethanol, acetone, and N-methylpyrrolidone.

[0074] According to some embodiments of this application, a dispersant may be added to the slurry during sand milling. The dispersant includes at least one of polyethylene glycol and polyacrylate, and the polyacrylate includes at least one of ammonium polyacrylate and sodium polyacrylate.

[0075] According to some embodiments of this application, the mass of the dispersant is 0.01%-5% of the mass of the coating material.

[0076] According to some embodiments of this application, the particle size D50 of the wet-milled slurry is <0.5 μm, and the particle size D100 of the slurry is <1 μm.

[0077] According to some embodiments of this application, the particle size D50 of the wet-milled slurry is <0.2 μm, and the particle size D100 of the slurry is <0.5 μm.

[0078] According to some embodiments of this application, the drying method includes at least one of spray drying and flash drying.

[0079] According to some embodiments of this application, the crushing can be achieved by means of double roll crushing, ball mill, air jet mill or mechanical mill.

[0080] S30: Nickel source, cobalt source, manganese source, second precipitant, second complexing agent, and second solvent are mixed and subjected to a second co-precipitation to obtain a multi-component material precursor. In this step, nickel salt, cobalt salt, and manganese salt are prepared into a second mixed solution according to the molar ratio of n(Ni):n(Co):n(Mn) = (1-ij):i:j). The second precipitant and the second complexing agent are prepared into a second precipitant solution and a second complexing agent solution, respectively. The second mixed solution, the second precipitant solution, and the second complexing agent solution are added to the reaction vessel, and a second co-precipitation is carried out in an inert atmosphere. The resulting solid-liquid mixed slurry is filtered, washed, dried, and sieved to obtain a multi-component material precursor.

[0081] According to some embodiments of this application, the nickel salt includes at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, nickel acetate, and nickel citrate.

[0082] According to some embodiments of this application, the cobalt salt includes at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, cobalt acetate, and cobalt citrate.

[0083] According to some embodiments of this application, the manganese salt includes at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese acetate, and manganese citrate.

[0084] According to some embodiments of this application, the second precipitant includes NaOH, and the molar concentration of the second precipitant solution can be 2 mol / L-15 mol / L. Specifically, the molar concentration of the second precipitant solution can be 5 mol / L-10 mol / L.

[0085] According to some embodiments of this application, the second complexing agent comprises ammonia, and the molar concentration of the second complexing agent solution can be 1 mol / L to 15 mol / L. Specifically, the molar concentration of the second complexing agent solution can be 5 mol / L to 10 mol / L.

[0086] According to some embodiments of this application, the molar concentration of the second mixed solution, calculated by metal element, can be 1 mol / L-3 mol / L, specifically, 1.5 mol / L-2.5 mol / L.

[0087] According to some embodiments of this application, the pH value of the second mixed solution during the second coprecipitation is 10-13. Specifically, the pH value of the second mixed solution during the second coprecipitation is 11-12.

[0088] According to some embodiments of this application, the temperature of the second mixed solution during the second coprecipitation is 40°C-80°C. Specifically, the temperature of the second mixed solution during the second coprecipitation is 50°C-70°C.

[0089] According to some embodiments of this application, the second co-precipitation time can be 5h-50h. Specifically, the second co-precipitation time can be 8h-32h.

[0090] According to some embodiments of this application, the particle size D50 of the multi-component material precursor can be 2μm-30μm. Specifically, the particle size D50 of the multi-component material precursor can be 3μm-20μm.

[0091] According to some embodiments of this application, the solid-liquid mixture slurry can be filtered by methods such as vacuum filtration, pressure filtration, and centrifugation.

[0092] According to some embodiments of this application, the filtered solid can be dried by hot air drying, infrared drying, microwave drying, or other methods.

[0093] S40: The multi-component material precursor, lithium source, and M'' source are mixed and subjected to a second calcination to obtain the multi-component material. The temperature of the second calcination is 650℃-1000℃. In this step, the multi-component material precursor, lithium source, and M'' source are mixed and calcined a second time, crushed, and sieved to obtain the multi-component material. The temperature of the second calcination is 650℃-1000℃.

[0094] As an example, the temperature of the second calcination can be 650℃, 750℃, 850℃, 950℃, 1000℃, etc., or can be a range of any of the above values.

[0095] According to some specific embodiments of this application, the temperature of the second calcination can be 750℃-900℃.

[0096] According to some embodiments of this application, the second calcination time can be 4h-48h. Specifically, the second calcination time can be 8h-24h.

[0097] By keeping the temperature and time of the second calcination within the above range, crystal growth and uniform distribution can be promoted, thereby enhancing the stability of the crystal structure.

[0098] According to some embodiments of this application, the lithium source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate.

[0099] According to some embodiments of this application, the lithium source is added in an amount with a molar ratio of 0.9 ≤ n(Li) / [n(Ni)+n(Co)+n(Mn)+n(M'')] ≤ 1.3. For example, n(Li) / [n(Ni)+n(Co)+n(Mn)+n(M'')] can be 0.9, 1, 1.1, 1.2, 1.3, etc., or can be a range of any of the above values. According to some specific embodiments of this application, 0.96 ≤ n(Li) / [n(Ni)+n(Co)+n(Mn)+n(M'')] ≤ 1.1.

[0100] By adding lithium sources within the above range, nickel-based multi-component materials with an R-3m space group and a complete α-NaFeO2 structure can be formed, thereby increasing the specific capacity of the multi-component materials and enabling the battery to have a higher energy density.

[0101] According to some embodiments of this application, the M'' source is selected from at least one of oxides containing M'', hydroxides containing M'', carbonates containing M'', nitrates containing M'', and sulfates containing M''.

[0102] According to some embodiments of this application, the M'' source is added in an amount with a molar ratio of 0 < n(M'') / [n(Ni)+n(Co)+n(Mn)]≤0.1, specifically, in an amount of 0.001≤n(M'') / [n(Ni)+n(Co)+n(Mn)]≤0.05.

[0103] When the amounts of M'' source and the multi-component material precursor meet the above range, the M'' element can improve the structural stability of the multi-component material, especially the structural stability after delithiation, thereby improving the safety of the battery.

[0104] According to some embodiments of this application, the crushing can be achieved by means of roller crushing, ball mill, air jet mill or mechanical mill.

[0105] According to some embodiments of this application, the screening can be achieved using an ultrasonic vibrating screen.

[0106] S50: The multi-element material and the coating material are mixed and subjected to a third calcination to obtain the positive electrode active material. The temperature of the third calcination is 600℃-900℃. In this step, the multi-element material and the coating material are mixed, calcined for the third time, crushed, and sieved to obtain the positive electrode active material.

[0107] According to some embodiments of this application, the temperature of the third calcination can be 600℃, 700℃, 800℃, 900℃, etc., or can be a range of any of the above values. According to some specific embodiments of this application, the temperature of the third calcination can be 650℃-850℃.

[0108] According to some embodiments of this application, the third calcination time can be 4h-48h. Specifically, the third calcination time can be 8h-24h.

[0109] By keeping the temperature and time of the third calcination within the above range, the residual stress inside the matrix can be reduced, the matrix crystal structure can be stabilized, a uniform coating material can be formed on the surface, the release of active oxygen in the delithiated state of the matrix can be suppressed, and problems such as shedding and structural changes of multi-component materials during repeated charging and discharging can be prevented, thereby maintaining a longer service life and higher energy density.

[0110] According to some embodiments of this application, when the multi-component material and the coating material are mixed, the mass of the coating material is m1, and the mass of the multi-component material is m2, satisfying 0.01% ≤ m1 / m2 ≤ 5%. For example, m1 / m2 can be 0.01%, 0.1%, 1%, 2%, 3%, 4%, 5%, etc., or can be a range of any of the above values. According to some specific embodiments of this application, 0.1% ≤ m1 / m2 ≤ 2%.

[0111] When the content of the coating material is within the above range, an ordered, locally structured coating material can be formed on the substrate surface, reducing the peak heat release of the positive electrode active material, thereby improving the thermal stability and cycle stability of the battery and enhancing the battery's safety performance.

[0112] According to some embodiments of this application, the particle size Dv50 of the multi-element material is 2μm-20μm, for example, it can be 2μm, 5μm, 10μm, 15μm, 20μm, etc., or it can be any range of the above values.

[0113] According to some specific embodiments of this application, the particle size Dv50 of the multi-element material is 3μm-15μm.

[0114] In this application, Dv50 refers to the particle size corresponding to a volume distribution percentage of 50%, which is determined using a Malver Master Size 3000 laser particle size analyzer in accordance with standard GB / T19077-2016.

[0115] According to some embodiments of this application, the specific surface area of ​​the multi-element material is 0.2 m². 2 / g-1.2m 2 / g, for example, can be 0.2m 2 / g, 0.4m 2 / g, 0.6m 2 / g, 0.8m 2 / g, 1m 2 / g, 1.2m 2 / g, etc., or a range consisting of any of the above values.

[0116] According to some specific embodiments of this application, the specific surface area of ​​the multi-element material is 0.4 m². 2 / g-1m 2 / g.

[0117] In this application, the specific surface area was determined using a US-made Gemini VII2390 multi-station fully automated specific surface area and porosity analyzer. Approximately 7g of sample was placed in a 9cc long tube with a bulb, degassed at 200℃ for 2 hours, and then placed in the main unit for testing to obtain the BET specific surface area data of the positive electrode active material.

[0118] In summary, the positive electrode active material and its preparation method proposed in this application have the following advantages: (1) By forming a coating material with low thermal conductivity and low phase formation temperature on at least part of the surface of the substrate, physical isolation can be formed between the substrate and the electrolyte, reducing side reactions between the substrate and the electrolyte, reducing electrolyte consumption, and improving the cycle performance of the battery.

[0119] (2) The coating material has high thermal stability and low thermal conductivity, which can reduce the heat release peak of the positive electrode active material, thereby improving the thermal stability and cycle stability of the battery and improving the safety performance of the battery.

[0120] (3) The oxygen vacancies in the coating material can effectively adsorb the active oxygen in the delithiated positive material, reduce the side reactions between the delithiated matrix material and the electrolyte, and improve the cycle performance of the battery.

[0121] (4) By controlling the content of the coating material on the substrate surface, the thermal stability and cycle stability of the positive electrode active material can be improved, while the content of the substrate material on the positive electrode sheet can be increased, thereby increasing the energy density of the battery.

[0122] (5) The method for forming a coating material on the substrate surface proposed in this application is simple, low-cost, and easy to scale up industrially.

[0123] The third aspect of this application provides a positive electrode sheet, including the positive active material provided in the first aspect of this application or the positive active material prepared by the method provided in the second aspect of this application.

[0124] The fourth aspect of this application provides a battery, including the positive electrode sheet provided in the third aspect of this application or the positive electrode active material provided in the first aspect of this application.

[0125] As an example, the battery can be a lithium-ion battery or a sulfide solid-state battery.

[0126] The fifth aspect of this application provides an electrical device, including the battery provided in the fourth aspect of this application.

[0127] The electrical equipment may include, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0128] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0129] Example 1 1. Preparation of positive electrode active materials Lanthanum salt LaCl3·7H2O, zirconium salt ZrOCl2·8H2O, and M' salt AlCl3 were prepared as a first mixed solution. The ratio of La:Zr:Al in the first mixed solution was 2:2:0.04, and the concentration of the metal element in the first mixed solution was 2 mol / L. The amount of dispersant PEG added was 0.5%. A 10 mol / L ammonia solution was prepared as the first complexing agent and precipitant solution. The reaction base liquid, which included ammonia and dispersant PEG, was added to the reaction vessel. The content of ammonia in the reaction base liquid was 3 g / L, and the pH value of the reaction base liquid was 10.1. The temperature of the reaction vessel was raised to 50℃, and the stirring speed was 700 rpm. The first mixed solution, ammonia, and dispersant PEG were added to the reaction vessel. The pH value of the reaction system was controlled at 10.1, the content of complexing agent was 3 g / L, the reaction temperature was 50℃, the stirring speed was 700 rpm, and the total addition time was 10 h to obtain a slurry. The slurry was washed three times with pure water at 70℃, with a stirring speed of 500 rpm during washing. After washing for 1 hour, the slurry was filtered to obtain a filter cake, which was then dried at 200℃ for 6 hours to obtain La2Zr2Al. 0.04 (OH) 14.12 .

[0130] La2Zr2Al 0.04 (OH)14.12 The material was first calcined at 750℃ with a heating rate of 5℃ / min and sintered for 8 hours. After sand milling (solvent was pure water, milling time was 5 hours, and the slurry particle size D50 was 0.05μm), drying (spray drying inlet air temperature 255℃, outlet air temperature 100℃) and crushing (airflow crushing), the coating material C1 was obtained. The physical properties of C1 are shown in Table 1.

[0131] Based on the metal element, a second mixed solution with a concentration of 2 mol / L was prepared by mixing nickel salt (nickel sulfate), cobalt salt (cobalt sulfate), and manganese salt (manganese sulfate) in a molar ratio of 93:3:4; and M source (aluminum sulfate), second precipitant (sodium hydroxide), and second complexing agent (ammonia) were respectively prepared into M source solution with a concentration of 0.1 mol / L, second precipitant solution with a concentration of 2 mol / L, and second complexing agent solution with a concentration of 6 mol / L. The second mixed solution, source M solution, second precipitant solution, and second complexing agent solution were added to a reaction vessel, and a co-precipitation reaction was carried out under an inert atmosphere (pH 11.2-11.8, temperature 60℃) to obtain a solid-liquid mixed slurry with a particle size D. 50 It is 4μm; Among them, source M is added in a molar ratio of [n(M)] / [n(Ni)+n(Co)+n(Mn)]=0.001; The above solid-liquid mixture was sequentially filtered, washed, dried, and sieved to obtain the general formula [(Ni 0.93 Co 0.03 Mn 0.04 ) 0.999 Al 0.001 Multi-component precursors of (OH)2; The above-mentioned multi-component material precursor, lithium source (lithium hydroxide), and M' source (zirconia, D) are combined. 50 It has a wavelength of 50nm and a specific surface area of ​​100m². 2 The nickel-based multi-element material was obtained by mixing (g) and calcining it a second time (at 810℃ for 12h), crushing and sieving. The lithium source is added in a molar ratio of [n(Li)] / [n(Ni)+n(Co)+n(Mn)+n(M)+n(M')]=1.03; the M' source is added in a molar ratio of [n(M')] / [n(Ni)+n(Co)+n(Mn)]=0.001; the general formula of the above nickel-based ternary material is Li 1.03 [(Ni 0.93 Co 0.03 Mn 0.04 ) 0.999 Al 0.001 ] 0.999 Zr 0.001 O2; The above-mentioned nickel-based multi-element material was used as the matrix and the above-mentioned coating material were mixed at a mass ratio of 100:0.3 and subjected to a third calcination (temperature 720℃, time 8h), crushed and sieved to obtain the positive electrode active material.

[0132] 2. Preparation of positive electrode sheet The positive electrode active material, acetylene black, and polyvinylidene fluoride were dispersed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 95:2.5:2.5. The mixture was coated onto aluminum foil and dried. The foil was then cut into positive electrode sheets with a diameter of 12 mm. The positive electrode sheets were then vacuum dried at 120 °C for 12 h and then vacuum sealed for storage.

[0133] 3. Negative electrode plate Use lithium metal sheets with a diameter of 16mm and a thickness of 1mm.

[0134] 4. Separating membrane Celgard porous membrane with a thickness of 25 μm.

[0135] 5. Electrolyte Using LiPF6 as the solute and equal volumes of ethylene carbonate, dimethyl carbonate, and diethyl carbonate as solvents, the concentration of LiPF6 was 1 mol / L.

[0136] 6.1 Assemble the button cell battery The positive electrode, separator, negative electrode, and electrolyte are assembled into a 2025 type button cell in an argon-filled glove box with a water content and oxygen content of less than 5 ppm.

[0137] 6.2 Assembling Sulfide Solid-State Batteries The positive electrode active material, acetylene black, polytetrafluoroethylene and Li 5.5 PS 4.5 Cl 1.5 Solid electrolytes were ground in a mortar at a mass ratio of 80:2:3:15 for 30 minutes to achieve uniform mixing. 10 mg of positive electrode active material was weighed and evenly dispersed at the bottom of a 10 mm diameter stainless steel mold. Then, 150 mg of Li... 5.5 PS 4.5 Cl 1.5 Solid electrolyte powder was poured into a mold, and then a 10mm diameter, 1mm thick lithium anode sheet was placed on top. The mold was then pressed under 600MPa pressure for 3 minutes to obtain a sandwich-structured all-solid-state lithium-ion battery based on a sulfide solid electrolyte. Finally, the battery was encapsulated in a 2025 battery casing. All of the above processes were carried out in an argon-filled glove box with both water and oxygen content less than 5ppm.

[0138] The battery preparation process in Examples 2-9, Comparative Examples 2 and 3 is the same as in Example 1, with the differences detailed in Tables 1 and 2.

[0139] Comparative Example 1 The battery is prepared using the same method as in Example 1, except that the coating material is prepared using the following method: Based on the stoichiometric ratio of La₂Zr₂O₇, lanthanum oxide and zirconium oxide were accurately weighed and mixed in a mixer at 850 rpm for 4 hours to ensure thorough and uniform mixing. The mixture was then calcined for the first time at 750°C with a heating rate of 5°C / min, and sintered for 8 hours. Subsequent milling, drying, and crushing were performed as in Example 1.

[0140] The preparation methods of the batteries in Examples 10-12, Comparative Examples 4 and 5 are the same as those in Example 3, and the differences are detailed in Table 2.

[0141] Table 1

[0142] Table 2

[0143] Performance testing 1. Full width at half maximum (FWHM) and peak intensity ratio of diffraction peaks The full width at half maximum (FWHM) and peak intensity ratio were obtained by fine-tuning using a Rigaku X-ray diffractometer.

[0144] 2.25℃ Discharge Specific Capacity Test Method The assembled 2025 coin cells were placed in a constant temperature environment at 25°C for 24 hours. Then, they were charged to 4.3V at a 0.1C charging current using a charge-discharge tester, followed by constant voltage charging until the charging current ≤0.01C, and then discharged to 3V at a 0.1C discharging current, forming two cycles. This process was then repeated with a 1C current. The charge-discharge capacity and cycle performance of the positive electrode active material in the liquid lithium-ion battery were investigated.

[0145] 3. Heat release test method The assembled 2025 button cell was placed in a constant temperature environment of 25°C for 24 hours. Then, it was charged to 4.3V with a charging current of 0.1C on a charge-discharge tester, then switched to constant voltage charging until the charging current was ≤0.01C, then discharged to 3V with a discharging current of 0.1C, and finally charged to 4.3V with a charging current of 0.1C, then switched to constant voltage charging until the charging current was ≤0.01C.

[0146] The fully charged 2025 coin cell was disassembled in an argon-filled glove box with both water and oxygen content less than 5 ppm to obtain the positive electrode sheet. The positive electrode sheet was then placed in a high-pressure crucible, sealed, and removed from the glove box. Finally, it was tested on a METTLER TGA / DSC 3+ device under the following conditions: 30℃-350℃, heating rate of 5℃ / min, N2 atmosphere, and carrier gas flow rate of 50mL / min.

[0147] 4. Charge / discharge capacity of sulfide solid-state batteries The sulfide solid-state battery was encapsulated in a 2025 battery case. All processes were conducted in an argon-filled glove box with both water and oxygen content less than 5 ppm. The assembled 2025 sulfide solid-state battery was placed in a constant temperature environment at 25°C for 24 hours, then charged to 4.3V at a 0.1C charging current on a charge-discharge tester, followed by constant voltage charging until the charging current ≤0.01C, and then discharged to 3V at a 0.1C discharging current, forming two cycles. The charge-discharge capacity of the positive electrode active material in the sulfide solid-state battery was investigated.

[0148] The test results of the batteries in Examples 1-12 and Comparative Examples 1-5 are shown in Table 3.

[0149] Table 3

[0150] As can be seen from Table 3, comparing Examples 1-12 with Comparative Examples 1-5, this application can reduce the peak heat release of the positive electrode active material and improve the cycle performance of the battery by forming a coating material on the surface of the matrix material.

[0151] As can be seen from the comparison of Example 3, Comparative Example 2, and Comparative Example 3, the temperature of the first calcination affects the FWHM of the coating material. （222） The half-peak width (WHM) of the coating material is as follows: if the WHM of the coating material is too small, it indicates that the coating material is too crystallinity and lacks sufficient surface activity; if the WHM of the coating material is too large, the crystal structure of the coating material is not regular enough, which affects the diffusion of ions in the electrode.

[0152] As can be seen from the comparison between Example 3 and Comparative Example 5, by controlling the temperature of the third calcination, a uniform coating material can be formed on the surface of the substrate, which can suppress the release of active oxygen in the delithiation state of the substrate, prevent the multi-element materials from falling off and undergoing structural changes during repeated charging and discharging, and improve the cycle performance of the battery.

[0153] As can be seen from Examples 1-4, by doping the coating material with ions having a radius greater than La... 3+ Smaller elements, or doped ions with radii smaller than Zr 4+Larger elements can increase oxygen vacancy defects, improve oxygen adsorption, and enhance ion and electron transport in the coating material, thereby improving battery capacity and cycle stability.

[0154] As can be seen from the comparison between Examples 3, 5 and 8, by adjusting the molar ratio of La and Zr, the content of impurity phases in the coating material can be controlled, the stability of the crystal structure of the coating material can be improved, and the cycle performance of the battery can be improved.

[0155] As can be seen from Examples 6 and 9, by adjusting the temperature and heating rate of the first calcination, the I of the coating material can be adjusted. (222) / I (440) The ratio improves the uniformity of the crystal structure, resulting in better oxygen adsorption, which in turn suppresses side reactions between the delithiated cathode material and the electrolyte, thus improving the cycle performance of the battery.

[0156] As can be seen from the comparison between Example 3 and Example 7, by controlling the median particle size D of the coating material after airflow atomization, 50 It can control the average particle size of the coating material on the substrate surface, thereby adjusting the battery's cycle performance and heat release peak, and improving the battery's safety performance.

[0157] As can be seen from the comparison of Examples 3, 11, 12 and Comparative Example 4, by controlling the content of the coating material on the substrate surface, the capacity and heat release peak of the battery can be optimized to obtain a battery with both high capacity and low heat release peak.

[0158] From the appendix Figure 2 It can be seen that the coating materials prepared in Examples 1-3 of this application can accelerate the reaction rate and improve ionic conductivity and charge transport efficiency by controlling the grain size and half-peak width through doping.

[0159] From the appendix Figure 3 It can be seen that the primary particles of the coating material are 50nm~100nm in size and have good dispersibility. These particles can provide more reaction sites, significantly improving efficiency and performance.

[0160] From the appendix Figure 4 It can be seen that a discontinuous coating material is formed on the surface of the substrate material. The coating material particles are about 50nm in size. After coating, the ionic and electronic conductivity can be improved, the capacity of the positive electrode active material can be fully utilized, and the energy density of the battery can be improved. Moreover, it can adsorb and store the active oxygen of the substrate material in a high delithiation state, suppress the side reactions between the positive electrode and the electrolyte, and improve the cycle life of the battery.

[0161] From the appendix Figure 5 As can be seen, the matrix material prepared in Comparative Example 1 has a smooth surface and no coating material is formed.

[0162] The descriptions of "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0163] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A positive electrode active material, characterized in that, include: The matrix comprises a compound represented by Formula I: Li x (Ni 1-i-j Co i Mn j M'' p )O2 of formula I, Wherein, M'' includes at least one element selected from B, P, Al, Ti, Y, Zr, La, Nb, Ta, W, V, Cr, Mo, and Sb, and 0.9≤x≤1.3, 0.02≤i≤0.2, 0<j≤0.2, and 0.002<p≤0.1; A coating material, the coating material being located on at least a portion of the surface of the substrate, the coating material comprising a compound represented by Formula II: La α Zr β M γ M’ δ O ε Formula II; Wherein, M includes at least one element selected from Li, Na, Ca, Mg, Ba, and Sr, and M' includes at least one element selected from Al, Ti, Sn, Nb, Ta, W, and Mo, 0 < α ≤ 3, 0 < β ≤ 2, 0 < γ < 0.5, 0 < δ < 0.5, and 5 ≤ ε ≤ 10; In the X-ray diffraction pattern of the coating material, the full width at half maximum (FWHM) of the diffraction peak (222) is 1000 m / s. （222） And satisfy: 0.3≤FWHM （222） ≤0.53; In the X-ray diffraction pattern of the coating material, the ratio of the peak intensity of diffraction peak (222) to that of diffraction peak (440) satisfies: 2.91 ≤ I （222） / I （440） ≤3.

5.

2. The positive electrode active material according to claim 1, characterized in that, Based on the total mass of the substrate, the mass percentage of the coating material is 0.05%-2%.

3. The positive electrode active material according to claim 2, characterized in that, The coating material accounts for 0.1%-0.5% of the total mass of the substrate.

4. The positive electrode active material according to claim 1 or 2, characterized in that, The proportion of impurity phases in the crystal structure of the coating material is less than or equal to 2%.

5. The positive electrode active material according to claim 4, characterized in that, The proportion of impurity phase in the crystal structure of the coating material is less than or equal to 1.5%.

6. The positive electrode active material according to claim 1 or 2, characterized in that, The average particle size D of the matrix 50 The range is 1.2μm-6.2μm.

7. The positive electrode active material according to claim 6, characterized in that, The average particle size D of the matrix 50 The range is 2.2μm-4.5μm.

8. The positive electrode active material according to claim 1 or 2, characterized in that, The average particle size of the coating material is 10nm-100nm.

9. A method for preparing the positive electrode active material according to any one of claims 1-8, characterized in that, include: Lanthanum source, zirconium source, M source, M' source, first precipitant, first complexing agent, and first solvent are mixed and subjected to a first co-precipitation, followed by drying to obtain La. α Zr β M γ M' δ Co-precipitation of precursors; For the La α Zr β M γ M' δ The coprecipitated precursor is subjected to a first calcination to obtain a coating material, wherein the temperature of the first calcination is 700℃-910℃. Nickel source, cobalt source, manganese source, second precipitant, second complexing agent, and second solvent are mixed and a second co-precipitation is performed to obtain a multi-component material precursor. The multi-component material precursor, lithium source, and M'' source are mixed and calcined a second time to obtain the multi-component material. The temperature of the second calcination is 650℃-1000℃. The multi-element material and the coating material are mixed and then calcined a third time to obtain the positive electrode active material. The temperature of the third calcination is 600℃-900℃.

10. The method according to claim 9, characterized in that, The temperature of the third calcination is 650℃-850℃.

11. The method according to claim 9, characterized in that, The third calcination time is 4h-48h.

12. The method according to claim 11, characterized in that, The third calcination time is 8h-24h.

13. The method according to claim 9, characterized in that, When the multi-component material and the coating material are mixed, the mass of the coating material is m1, the mass of the multi-component material is m2, and the mixture satisfies 0.01%≤m1 / m2≤5%.

14. The method according to claim 13, characterized in that, 0.1%≤m1 / m2≤2%.

15. The method according to claim 9, characterized in that, The heating rate for the first calcination is 0.5℃ / min-10℃ / min.

16. The method according to claim 15, characterized in that, The heating rate for the first calcination is 1℃ / min - 5℃ / min.

17. The method according to claim 9, characterized in that, The first calcination time is 5h-24h.

18. The method according to claim 17, characterized in that, The first calcination time is 8h-18h.

19. The method according to claim 9, characterized in that, The temperature of the second calcination is 750℃-900℃.

20. The method according to claim 9, characterized in that, The second calcination time is 4h-48h.

21. The method according to claim 20, characterized in that, The second calcination time is 8h-24h.

22. The method according to claim 9, characterized in that, The particle size Dv50 of the multi-element material is 2μm-20μm.

23. The method according to claim 22, characterized in that, The particle size Dv50 of the multi-element material is 3μm-15μm.

24. The method according to claim 9, characterized in that, The specific surface area of ​​the multi-element material is 0.2 m². 2 / g-1.2m 2 / g.

25. The method according to claim 24, characterized in that, The specific surface area of ​​the multi-element material is 0.4 m². 2 / g-1m 2 / g.

26. The method according to claim 9, characterized in that, The pH value of the first coprecipitation is 7.5-11.5, and the temperature is 30℃-55℃.

27. The method according to claim 9, characterized in that, The second coprecipitation occurs at a pH of 10-13 and a temperature of 40℃-80℃.

28. A positive electrode sheet, characterized in that, The positive electrode active material includes any one of claims 1-8 or any one of claims 9-27 prepared by the method thereof.

29. A battery, characterized in that, It includes the positive electrode sheet as described in claim 28 or the positive electrode active material as described in any one of claims 1-8.

30. An electrical appliance, characterized in that, Includes the battery as described in claim 29.

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