Positive electrode active material and preparation method thereof, positive electrode plate, battery and electric equipment

Abstract

The invention provides a positive active material and a preparation method thereof, a positive pole piece, a battery and electric equipment. The positive active material comprises a substrate, the coating material comprises a compound as shown in a formula II: La [alpha] Zr [beta] M [gamma] M '[delta] O [epsilon]; wherein M comprises at least one element of Li, Na, Ca, Mg, Ba and Sr, M'comprises at least one element of Al, Ti, Sn, Nb, Ta, W and Mo, alpha is larger than 0 and smaller than or equal to 3, beta is larger than 0 and smaller than or equal to 2, gamma is larger than or equal to 0 and smaller than 0.5, delta is larger than or equal to 0 and smaller than 0.5, and epsilon is larger than or equal to 5 and smaller than or equal to 10. In an X-ray diffraction pattern of the coating material, the half-peak width of a diffraction peak (222) is FWHM (222), and FWHM (222) is more than or equal to 0.3 and less than or equal to 0.53. Therefore, the coating material is relatively low in thermal conductivity, can form physical isolation on the surface of a multi-element material, and can effectively adsorb active oxygen removed from a high-lithium-removal-state matrix material, reduce side reaction between a matrix and an electrolyte and reduce a heat release peak value of a positive electrode active material, so that the thermal stability and the cycling stability of a battery are improved, and the service life of the battery is prolonged. The safety performance of the battery is improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular, to positive electrode active materials and preparation methods thereof, positive electrode sheets, batteries, and electrical equipment. Background Art

[0002] In recent years, my country's new energy vehicle industry has grown rapidly and has gained a leading edge in the three major systems of batteries, electronic control, and electric drive. At the same time, new energy vehicles still have problems such as mileage anxiety and safety hazards. In view of this, there is an urgent need to develop lithium batteries with higher energy density and safety. As the core key material of lithium batteries, the positive electrode directly determines the performance level of the battery. Nickel manganese cobalt oxide lithium positive electrode active materials (referred to as multi-materials) have higher specific capacity, energy density and power density, as well as relatively stable performance, making them popular materials for commercial positive electrodes.

[0003] At present, the mainstream development direction of multi-element materials is high nickel, single crystal and high voltage. However, the structure of high nickel multi-element materials is unstable under high charge cut-off voltage, and the layered structure is converted into spinel structure. High nickel multi-element materials also have problems such as lithium nickel mixing, TM (transition metal)-O bond instability and lattice oxygen release during charging and discharging. The main methods to improve the thermal stability of high nickel multi-element materials include single crystal, bulk element doping and surface coating modification. Single crystal and bulk doping often reduce capacity while improving thermal stability. Surface coating can effectively inhibit the side reaction between the positive electrode active material and the electrolyte, stabilize the surface structure, inhibit irreversible phase change and prevent gas precipitation, thereby improving the structural stability and thermal stability of multi-element materials. However, the thermal stability and cycle life of multi-element materials still cannot meet the demand. Summary of the invention

[0004] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0005] In a first aspect, the present application provides a positive electrode active material, wherein the positive electrode active material comprises a matrix, wherein 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, 0.9≤x≤1.3, 0.02≤i≤0.2, 0<j≤0.2, 0.002<p≤0.1; a coating material, the coating material is located on at least a portion of the surface of the substrate, and the coating material includes a compound shown in formula II: La α Zr β M γM' δ O ε Formula II; wherein M includes at least one element selected from Li, Na, Ca, Mg, Ba, and Sr, 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, 5≤ε≤10; in the X-ray diffraction pattern of the coating material, the half-peak width 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 physical isolation on the surface of the multi-element material, reduce the side reaction between the matrix and the electrolyte, reduce the peak heat release of the positive electrode active material, and thus improve the thermal stability and cycle stability of the battery and improve the safety performance of the battery.

[0006] According to some embodiments of the present application, based on the total mass of the substrate, the mass proportion of the coating material is 0.05%-2%, and optionally 0.1%-0.5%, thereby reducing the heat release peak of the positive electrode active material and improving the thermal stability of the battery.

[0007] According to some embodiments of the present application, in the X-ray diffraction spectrum of the coating material, the ratio of the peak intensity of the diffraction peak (222) to the peak intensity of the diffraction peak (440) satisfies: 2.8≤I (222) / I (440) ≤3.5. As a result, the coating material has a high degree of crystallization and good crystal plane orientation, showing a better oxygen adsorption effect, thereby inhibiting the side reaction between the de-lithiated positive electrode material and the electrolyte, and improving the electrochemical performance of the positive electrode material.

[0008] According to some embodiments of the present application, the proportion of the impurity phase in the crystal structure of the coating material is less than or equal to 2%, and optionally, the proportion of the 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 the present application, the positive electrode active material satisfies at least one of the following conditions: the average particle size D of the matrix 50 1.2μm-6.2μm, preferably, D 50 The average particle size of the coating material is 2.2 μm-4.5 μm, and the average particle size of the coating material is 10 nm-100 nm. Thus, the coating material can provide more chemical reaction sites, accelerate the rate of chemical reaction, and exhibit ionic conductivity and high charge transfer efficiency.

[0010] The second aspect of the present application provides a method for preparing the positive electrode active material provided in the first aspect of the present application, the method comprising:

[0011] The lanthanum source, zirconium source, M source, M' source, the first precipitant, the first complexing agent, and the first solvent are mixed to perform the first coprecipitation and dried to obtain La α Zr β M γ M' δ coprecipitate precursor; α Zr β M γ M' δ The coprecipitated precursor is calcined for the first time to obtain the coating material, and the temperature of the first calcination is 700°C-910°C; the nickel source, the cobalt source, the manganese source, the second precipitant, the second complexing agent, and the second solvent are mixed and coprecipitated for the second time to obtain the multi-material precursor; the multi-material precursor, the lithium source, and the M" source are mixed and calcined for the second time to obtain the multi-material, and the temperature of the second calcination is 650°C-1000°C; the multi-material and the coating material are mixed and calcined for the third time to obtain the positive electrode active material, and the temperature of the third calcination is 600°C-900°C. Thus, a uniform coating material can be formed on the surface of the multi-material. Since the thermal conductivity of the coating material is low, the heat release peak of the positive electrode active material can be reduced, thereby improving the thermal stability and cycle stability of the battery, and improving the safety performance of the battery. At the same time, the method for preparing the positive electrode active material proposed in the present application is simple in process, low in cost, and easy to scale up.

[0012] According to some embodiments of the present application, the temperature of the third calcination is 650°C-850°C; and / or the time of the third calcination is 4h-48h, optionally 8h-24h.

[0013] According to some embodiments of the present application, when the multi-material and the coating material are mixed, the mass of the coating material is m1, the mass of the multi-material is m2, and 0.01%≤m1 / m2≤5% is satisfied, optionally, 0.1%≤m1 / m2≤2%.

[0014] According to some embodiments of the present application, the method satisfies at least one of the following conditions: the heating rate of the first calcination is 0.5°C / min-10°C / min, and can be optionally 1°C / min-5°C / min; the time of the first calcination is 5h-24h, and can be optionally 8h-18h; the temperature of the second calcination is 750°C-900°C; the time of the second calcination is 4h-48h, and can be optionally 8h-24h.

[0015] According to some embodiments of the present application, the method satisfies at least one of the following conditions: the particle size Dv50 of the multi-material is 2 μm-20 μm, and can be 3 μm-15 μm; the specific surface area of ​​the multi-material is 0.2 m 2 / g-1.2m 2 / g, optional 0.4m 2 / g-1m 2 / g.

[0016] According to some embodiments of the present application, at least one of the following conditions is met: the pH value of the first co-precipitation is 7.5-11.5, and the temperature is 30°C-55°C; the pH value of the second co-precipitation is 10-13, and the temperature is 40°C-80°C.

[0017] The third aspect of the present application provides a positive electrode plate, comprising the positive electrode active material provided in the first aspect of the present application or the positive electrode active material prepared by the method provided in the second aspect of the present application.

[0018] The fourth aspect of the present application provides a battery, comprising the positive electrode plate provided by the third aspect of the present application or the positive electrode active material provided by the first aspect of the present application.

[0019] The fifth aspect of the present application provides an electrical device, including the battery provided by the fourth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 A schematic flow chart of a method for preparing a positive electrode active material according to an embodiment of the present application is shown.

[0022] Figure 2 The XRD patterns of the coating materials prepared in Examples 1 to 3 of the present application are shown.

[0023] Figure 3 The SEM image of the coating material prepared in Example 1 of the present application is shown.

[0024] Figure 4 The SEM image of the positive electrode active material prepared in Example 1 of the present application is shown.

[0025] Figure 5 The SEM image of the positive electrode active material prepared in Comparative Example 1 of the present application is shown. DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the document in this area or the product specification are used. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained commercially.

[0027] In a first aspect, the present application provides a positive electrode active material, the positive electrode active material comprising:

[0028] A matrix, wherein the matrix comprises a compound represented by formula I:

[0029] Li x (Ni 1-i-j Co i Mn j M” p )O2 Formula I,

[0030] Wherein, M" includes at least one element selected from B, P, Al, Ti, Y, Zr, La, Nb, Ta, W, V, Cr, Mo, and Sb, 0.9≤x≤1.3, 0.02≤i≤0.2, 0<j≤0.2, 0.002<p≤0.1;

[0031] A coating material, the coating material is located on at least a portion of the surface of the substrate, and the coating material includes a compound shown in Formula II:

[0032] La α Zr β M γ M' δ O ε Formula II;

[0033] Wherein, M includes at least one element selected from Li, Na, Ca, Mg, Ba, and Sr, 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, 5≤ε≤10;

[0034] In the X-ray diffraction pattern of the coating material, the half-peak width of the diffraction peak (222) is FWHM (222) , and satisfy: 0.3≤FWHM (222) ≤0.53.

[0035] The positive electrode active material proposed in this application has the following advantages:

[0036] (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 half-peak width FWHM can be increased.(222) , improve the adsorption of active oxygen by the coating material and reduce the thermal conductivity of the coating material.

[0037] (2) By forming the coating material proposed in the present application on at least part of the surface of the substrate, a physical isolation can be formed between the substrate and the electrolyte, thereby reducing the contact between the substrate and the electrolyte, reducing the side reaction between the positive electrode active material and the electrolyte, reducing the consumption of the electrolyte, and improving the cycle performance of the battery.

[0038] (3) The coating material has high thermal stability and low thermal conductivity, which can reduce the peak heat release 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.

[0039] (4) The oxygen vacancies in the coating material can effectively adsorb the active oxygen in the de-lithiated positive material, reduce the side reactions between the de-lithiated matrix material and the electrolyte, and improve the cycle performance of the battery.

[0040] In this application, the X-ray diffraction test method is to use a Rigaku X-ray automatic diffractometer to perform phase and crystal structure analysis, with an operating voltage of 40kV, an operating current of 200mA, continuous scanning, a scanning speed of 3° / min, a step length of 0.02°, and a scanning angle of 10°-80°. The FWHM of the material can be calculated using the Rigaku Information collector tool software. (222) .

[0041] If the half-peak width of the coating material is too small, it indicates that the coating material is too crystalline and lacks sufficient surface activity; if the half-peak width 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.

[0042] As an example, the FWHM of the cladding material (222) It may be 0.3, 0.35, 0.4, 0.45, 0.5, etc., or may be a range consisting of any of the above values.

[0043] As an example, x may be 0.9, 1, 1.1, 1.2, 1.3, etc., or may be in a range consisting of any of the above values. Thus, the gram capacity of the positive electrode active material is increased, and the energy density of the battery is increased.

[0044] It should be noted that, as the battery undergoes formation and cycling, lithium ions will be consumed, so the measured lithium content x in the positive electrode active material may be less than 1. At the same time, if the positive electrode and negative electrode sheets use a lithium supplement, the measured lithium content x in the positive electrode active material may be greater than 1 after the battery undergoes formation and cycling.

[0045] As an example, i may be 0.02, 0.05, 0.1, 0.15, 0.2, etc., or may be any range of the above values. Thus, the electronic conductivity of the matrix material is improved, and the specific capacity and rate performance of the battery are improved.

[0046] As an example, j can be 0.05, 0.1, 0.15, 0.2, etc., or can be any range of the above values. Thus, the structural stability of the matrix material is improved, and the cycle performance of the battery is improved.

[0047] As an example, p may be 0.005, 0.01, 0.05, 0.1, etc., or may be a range of any of the above values. Thus, the structural stability of the matrix material is improved, especially the structural stability of the matrix material after lithium removal, and the cycle performance of the battery is improved.

[0048] As an example, α may be 1, 2, 3, etc., or may be a range consisting of any of the above values.

[0049] As an example, β may be 0.5, 1, 1.5, 2, etc., or may be a range consisting of any of the above values.

[0050] As an example, γ may be 0.1, 0.2, 0.3, 0.4, 0.45, etc., or may be a range consisting of any of the above values.

[0051] As an example, δ may be 0.1, 0.2, 0.3, 0.4, 0.45, etc., or may be a range consisting of any of the above values.

[0052] As an example, ε may be 5, 6, 7, 8, 9, 10, etc., or may be a range consisting of any of the above values.

[0053] According to some embodiments of the present application, based on the total mass of the substrate, the mass proportion of the coating material can be 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, etc., or can be a range composed of any of the above numerical values. Specifically, when preparing the positive electrode active material, the content of the coating material on the surface of the substrate can be controlled by controlling the amount of the multi-material and the coating material added. If the content of the coating material is too little, the effect of reducing the peak value of the thermal release of the positive electrode active material is not obvious. By making the content of the coating material within the above range, the content of the substrate material on the positive electrode sheet can be increased while reducing the peak value of the thermal release of the positive electrode active material, thereby increasing the energy density of the battery.

[0054] According to some specific embodiments of the present application, based on the total mass of the substrate, the mass proportion of the coating material is 0.1%-0.5%.

[0055] According to some embodiments of the present application, in the X-ray diffraction spectrum of the coating material, the ratio of the peak intensity of the diffraction peak (222) to the peak intensity of the 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 can be a range composed of any of the above values. As a result, the coating material has a high degree of crystallinity and good crystal plane orientation, showing a better oxygen adsorption effect, thereby inhibiting the side reaction between the de-lithiation positive electrode material and the electrolyte, and improving the electrochemical performance of the positive electrode material.

[0056] According to some embodiments of the present application, the proportion of the 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 a range composed of any of the above values. Thus, the coating material has a more stable crystal structure, provides more active sites, and exhibits better electrochemical performance.

[0057] 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 element and Zr element.

[0058] According to some specific embodiments of the present application, the proportion of the heterogeneous phase in the crystal structure of the coating material is less than or equal to 1.5%.

[0059] According to some embodiments of the present application, the average particle size D of the matrix material 50 is 1.2 μm-6.2 μm, for example, 1.2, 2.2, 3.2, 4.2, 5.2, 6.2, etc., or can be any range of the above values. According to some specific embodiments of the present application, D 50 2.2μm-4.5μm.

[0060] According to some embodiments of the present application, the average particle size of the coating material is 10nm-100nm. For example, it can be 10nm, 30nm, 50nm, 70nm, 90nm, 100nm, etc., so that the coating material can provide more chemical reaction sites, accelerate the rate of chemical reaction, and improve the ionic conductivity and charge transfer efficiency of the positive electrode active material.

[0061] In the present application, the testing method for the average particle size of the coating material is: using a scanning electron microscope (SEM) at a magnification of 30k to analyze the particle size of the coating material on the surface of the base material, testing the particle size of 50 coated particles, and taking the average value, which is the average particle size of the coating material.

[0062] It should be noted that, in the process of preparing 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 air flow crushing.

[0063] The second aspect of the present application provides a method for preparing the positive electrode active material provided in the first aspect of the present application, the method comprising:

[0064] The lanthanum source, zirconium source, M source, M' source, the first precipitant, the first complexing agent, and the first solvent are mixed to perform the first coprecipitation and dried to obtain La α Zr β M γ M' δ coprecipitate precursor; α Zr β M γ M' δ The coprecipitated precursor is calcined for the first time to obtain the coating material, and the temperature of the first calcination is 600°C-950°C; the nickel source, the cobalt source, the manganese source, the second precipitant, the second complexing agent, and the second solvent are mixed and coprecipitated for the second time to obtain the multi-material precursor; the multi-material precursor, the lithium source, and the M" source are mixed and calcined for the second time to obtain the multi-material, and the temperature of the second calcination is 700°C-910°C; the multi-material and the coating material are mixed and calcined for the third time to obtain the positive electrode active material, and the temperature of the third calcination is 600°C-900°C. Thus, a uniform coating material can be formed on the surface of the multi-material. Since the thermal conductivity of the coating material is low, the heat release peak of the positive electrode active material can be reduced, thereby improving the thermal stability and cycle stability of the battery, and improving the safety performance of the battery. At the same time, the method for preparing the positive electrode active material proposed in the present application is simple in process, low in cost, and easy to scale up.

[0065] The method proposed in this application is described in detail below. Figure 1 , the method comprising:

[0066] S10: Mix the lanthanum source, zirconium source, M source, M' source, the first precipitant, the first complexing agent, and the first solvent, perform the first coprecipitation, and dry to obtain La α Zr β M γ M' δ Co-precipitation precursor

[0067] In this step, the lanthanum source, zirconium source, M source, and M' source are prepared into a first mixed solution, the first complexing agent and the first precipitating agent are respectively prepared into a first complexing agent solution and a first precipitating agent solution, and the first mixed solution, the first precipitating agent solution, and the first complexing agent solution are added to the reactor in the presence of a reaction base liquid to perform a first coprecipitation, and after the reaction is completed, the reaction is aged, washed, and dried to obtain La α Zr β M γ M' δ Co-precipitation precursor.

[0068] According to some embodiments of the present application, the lanthanum source includes a lanthanum salt, and the lanthanum salt includes at least one of a nitrate and a chloride containing lanthanum.

[0069] According to some embodiments of the present application, the concentration of the first mixed solution is 0.5 mol / L-3 mol / L in terms of metal elements. According to some specific embodiments of the present application, the concentration of the first mixed solution is 1 mol / L-2.5 mol / L.

[0070] According to some embodiments of the present application, the first precipitant includes at least one of NaOH, KOH, LiOH, Na2CO3, K2CO3, NH4HCO3 and (NH4)2CO3.

[0071] According to some embodiments of the present application, the concentration of the first precipitant solution may be 1 mol / L-10 mol / L.

[0072] According to some embodiments of the present application, the first complexing agent includes at least one of ammonia water and ethylenediaminetetraacetic acid.

[0073] According to some embodiments of the present application, the concentration of the first complexing agent solution is 4 mol / L-13 mol / L.

[0074] According to some embodiments of the present application, the pH value of the first coprecipitation reaction solution may be 7.5-11.5, for example, 7.5, 8.5, 9.5, 10.5, 11.5, etc., or may be a range consisting of any of the above values.

[0075] According to some embodiments of the present application, the temperature of the first coprecipitation reaction solution can be 30°C-55°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, etc., or can be a range consisting of any of the above numerical values.

[0076] According to some embodiments of the present application, in the first co-precipitation reaction, the stirring speed may be 300 rpm-800 rpm, and the co-flow time may be 5 h-60 h.

[0077] By carrying out the first coprecipitation under the above conditions, uniform precipitation of the metal elements can be achieved.

[0078] According to some embodiments of the present application, the aging time may be 0.5h-4h, for example, 0.5h, 1h, 2h, 3h, 4h, etc., or may be a range consisting of any of the above numerical values.

[0079] According to some embodiments of the present application, pure water may be used to wash the precipitate, and the temperature of the pure water may be 50°C-80°C.

[0080] S20: for the La α Zr β M γ M' δ The coprecipitated precursor is first calcined to obtain a coating material, wherein the first calcination temperature is 700°C-910°C.

[0081] In this step, the La α Zr β M γ M' δ The coprecipitated precursor is subjected to a first calcination, sand milling, drying and crushing to obtain a coating material. The temperature of the first calcination may be 700°C-910°C.

[0082] Specifically, the dry atmosphere may be formed of dry air, dry oxygen, or the like.

[0083] According to some embodiments of the present application, the heating rate of the first calcination is 0.5°C / min-10°C / min, for example, 0.5°C / min, 1°C / min, 3°C / min, 5°C / min, 7°C / min, 9°C / min, 10°C / min, etc., or can be a range composed of any of the above values. According to some specific embodiments of the present application, the heating rate of the first calcination is 1°C / min-5°C / min.

[0084] According to some embodiments of the present application, the temperature of the first calcination may be 700° C., 800° C., 900° C., 910° C., etc., or may be a range consisting of any of the above numerical values.

[0085] According to some embodiments of the present application, the first calcination time may be 5h-24h, for example, 5h, 10h, 15h, 20h, 24h, etc., or may be a range of any of the above values. According to some specific embodiments of the present application, the first calcination time is 8h-18h.

[0086] By making the heating rate, temperature and time of the first calcination within the above range, it is helpful to reduce the stress inside the material, obtain a uniform crystal structure, improve the crystallinity of the material, and reduce the agglomeration between particles.

[0087] According to some embodiments of the present application, the sanding solvent may include at least one of water, ethanol, acetone, and N-methylpyrrolidone.

[0088] According to some embodiments of the present application, a dispersant may be added to the slurry during the sand grinding, and the dispersant includes at least one of polyethylene glycol and polyacrylate, and the polyacrylate includes at least one of ammonium polyacrylate and sodium polyacrylate.

[0089] According to some embodiments of the present application, the mass of the dispersant is 0.01%-5% of the mass of the coating material.

[0090] According to some embodiments of the present application, the particle size D50 of the slurry after wet grinding is less than 0.5 μm, and the particle size D100 of the slurry is less than 1 μm.

[0091] According to some embodiments of the present application, the particle size D50 of the slurry after wet grinding is less than 0.2 μm, and the particle size D100 of the slurry is less than 0.5 μm.

[0092] According to some embodiments of the present application, the drying method includes at least one of spray drying and flash evaporation.

[0093] According to some embodiments of the present application, the crushing can be achieved by roller crushing, ball mill, air flow mill or mechanical mill.

[0094] S30: Mix the nickel source, the cobalt source, the manganese source, the second precipitant, the second complexing agent, and the second solvent to perform a second co-precipitation to obtain a multi-material precursor.

[0095] 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, and the second precipitant and the second complexing agent are respectively prepared into a second precipitant solution and a second complexing agent solution. The second mixed solution, the second precipitant solution and the second complexing agent solution are added to a reaction kettle, and a second co-precipitation is carried out in an inert atmosphere. The obtained solid-liquid mixed slurry is filtered, washed, dried and sieved to obtain a multi-material precursor.

[0096] According to some embodiments of the present application, the nickel salt includes at least one of nickel-containing sulfate, nickel-containing nitrate, nickel-containing chloride, nickel-containing oxalate, nickel-containing acetate, and nickel-containing citrate.

[0097] According to some embodiments of the present application, the cobalt salt includes at least one of cobalt-containing sulfate, cobalt-containing nitrate, cobalt-containing chloride, cobalt-containing oxalate, cobalt-containing acetate, and cobalt-containing citrate.

[0098] According to some embodiments of the present application, the manganese salt includes at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese acetate, and manganese citrate.

[0099] According to some embodiments of the present application, the second precipitant includes NaOH, and the molar concentration of the second precipitant solution may be 2 mol / L-15 mol / L. Specifically, the molar concentration of the second precipitant solution may be 5 mol / L-10 mol / L.

[0100] According to some embodiments of the present application, the second complexing agent includes ammonia water, and the molar concentration of the second complexing agent solution may be 1 mol / L-15 mol / L. Specifically, the molar concentration of the second complexing agent solution may be 5 mol / L-10 mol / L.

[0101] According to some embodiments of the present application, the molar concentration of the second mixed solution may be 1 mol / L-3 mol / L, specifically, 1.5 mol / L-2.5 mol / L, calculated as metal elements.

[0102] According to some embodiments of the present application, the pH value of the second mixed solution during the second co-precipitation is 10-13. Specifically, the pH value of the second mixed solution during the second co-precipitation is 11-12.

[0103] According to some embodiments of the present application, the temperature of the second mixed solution during the second co-precipitation is 40° C.-80° C. Specifically, the temperature of the second mixed solution during the second co-precipitation is 50° C.-70° C.

[0104] According to some embodiments of the present application, the second co-precipitation time may be 5h-50h. Specifically, the second co-precipitation time may be 8h-32h.

[0105] According to some embodiments of the present application, the particle size D50 of the multi-material precursor may be 2 μm-30 μm. Specifically, the particle size D50 of the multi-material precursor may be 3 μm-20 μm.

[0106] According to some embodiments of the present application, the solid-liquid mixed slurry may be filtered by suction filtration, filter pressing, centrifugation, etc.

[0107] According to some embodiments of the present application, after filtration, the solid can be dried by hot air drying, infrared drying, microwave drying, etc.

[0108] S40: Mix the multi-material precursor, lithium source, and M" source and perform a second calcination to obtain a multi-material. The temperature of the second calcination is 650°C-1000°C.

[0109] In this step, the multi-material precursor, lithium source and M" source are mixed and calcined for the second time, crushed and sieved to obtain the multi-material. The temperature of the second calcination is 650°C-1000°C.

[0110] As an example, the temperature of the second calcination may be 650° C., 750° C., 850° C., 950° C., 1000° C., etc., or may be a range consisting of any of the above values.

[0111] According to some specific embodiments of the present application, the temperature of the second calcination may be 750°C-900°C.

[0112] According to some embodiments of the present application, the second calcination time may be 4h-48h. Specifically, the second calcination time may be 8h-24h.

[0113] By setting the temperature and time of the second calcination within the above ranges, the growth and uniform distribution of crystals can be promoted and the stability of the crystal structure can be enhanced.

[0114] According to some embodiments of the present application, the lithium source includes at least one of lithium carbonate, lithium hydroxide and lithium nitrate.

[0115] According to some embodiments of the present application, the lithium source is added in an amount according to 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 consisting of any of the above numerical values. According to some specific embodiments of the present application, 0.96≤n(Li) / [n(Ni)+n(Co)+n(Mn)+n(M”)]≤1.1.

[0116] By adding the lithium source in the above range, a nickel-based multi-component material having an α-NaFeO2 structure with an R-3m space group and complete crystal form can be formed, thereby increasing the gram capacity of the multi-component material and making the battery have a higher energy density.

[0117] According to some embodiments of the present application, the M" source is selected from at least one of an oxide containing M", a hydroxide containing M", a carbonate containing M", a nitrate containing M" and a sulfate containing M".

[0118] According to some embodiments of the present application, the M" source is added in an amount of a molar ratio of 0<n(M") / [n(Ni)+n(Co)+n(Mn)]≤0.1, specifically, added in an amount of 0.001≤n(M") / [n(Ni)+n(Co)+n(Mn)]≤0.05.

[0119] When the amounts of the M" source and the multi-material precursor meet the above ranges, the M" element can improve the structural stability of the multi-material, especially the structural stability after lithium removal, thereby improving the safety of the battery.

[0120] According to some embodiments of the present application, the crushing can be achieved by roller crushing, ball mill, air flow mill or mechanical mill.

[0121] According to some embodiments of the present application, the screening can be achieved by using an ultrasonic vibration screen.

[0122] S50: Mix the multi-material and the coating material, and perform a third calcination to obtain the positive electrode active material, wherein the temperature of the third calcination is 600° C.-900° C.

[0123] In this step, the multi-material and the coating material are mixed, calcined for the third time, crushed, and sieved to obtain the positive electrode active material.

[0124] According to some embodiments of the present application, the temperature of the third calcination may be 600°C, 700°C, 800°C, 900°C, etc., or may be a range of any of the above values. According to some specific embodiments of the present application, the temperature of the third calcination may be 650°C-850°C.

[0125] According to some embodiments of the present application, the third calcination time may be 4h-48h. Specifically, the third calcination time may be 8h-24h.

[0126] By keeping the temperature and time of the third calcination within the above range, the residual stress inside the matrix can be reduced, the crystal structure of the matrix can be stabilized, a uniform coating material can be formed on the surface, the release of active oxygen in the delithiation state of the matrix can be inhibited, and the multi-material can be prevented from falling off and structural changes during repeated charging and discharging, thereby maintaining a longer service life and a higher energy density.

[0127] According to some embodiments of the present application, when the multi-material and the coating material are mixed, the mass of the coating material is m1, the mass of the multi-material is m2, and 0.01%≤m1 / m2≤5% is satisfied. For example, m1 / m2 can be 0.01%, 0.1%, 1%, 2%, 3%, 4%, 5%, etc., or can be a range consisting of any of the above values. According to some specific embodiments of the present application, 0.1%≤m1 / m2≤2%.

[0128] 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 improving the safety performance of the battery.

[0129] According to some embodiments of the present application, the particle size Dv50 of the multi-material is 2μm-20μm, for example, it can be 2μm, 5μm, 10μm, 15μm, 20μm, etc., or it can be a range composed of any of the above values.

[0130] According to some specific embodiments of the present application, the particle size Dv50 of the multi-material is 3 μm-15 μm.

[0131] In the present application, Dv50 refers to the particle size corresponding to when the volume distribution percentage reaches 50%, and is measured using a Malver Master Size 3000 laser particle size analyzer with reference to standard GB / T19077-2016.

[0132] According to some embodiments of the present application, the specific surface area of ​​the multi-element material is 0.2 m 2 / g-1.2m 2 / g, for example, it 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 may be within the range consisting of any of the above values.

[0133] According to some specific embodiments of the present application, the specific surface area of ​​the multi-element material is 0.4 m 2 / g-1m 2 / g.

[0134] In this application, the specific surface area is measured using the American Micromeritics multi-station fully automatic specific surface area and pore analyzer GeminiVII2390. About 7g of sample is placed in a 9cc long tube with a bulb, degassed at 200℃ for 2h, and then placed in a host for testing to obtain the BET specific surface area data of the positive electrode active material.

[0135] In general, the positive electrode active material and the preparation method thereof proposed in this application have the following advantages:

[0136] (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, a physical isolation can be formed between the substrate and the electrolyte, thereby reducing the side reactions between the substrate and the electrolyte, reducing the consumption of the electrolyte, and improving the cycle performance of the battery.

[0137] (2) The coating material has high thermal stability and low thermal conductivity, which can reduce the peak heat release 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.

[0138] (3) The oxygen vacancies in the coating material can effectively adsorb the active oxygen in the de-lithiated positive material, reduce the side reactions between the de-lithiated matrix material and the electrolyte, and improve the cycle performance of the battery.

[0139] (4) By controlling the content of the coating material on the surface of the substrate, the thermal stability and cycle stability of the positive electrode active material can be improved while increasing the content of the substrate material on the positive electrode sheet and improving the energy density of the battery.

[0140] (5) The method for forming a coating material on the surface of a substrate proposed in the present application has a simple process, low cost, and is easy to scale up industrially.

[0141] The third aspect of the present application provides a positive electrode plate, comprising the positive electrode active material provided in the first aspect of the present application or the positive electrode active material prepared by the method provided in the second aspect of the present application.

[0142] The fourth aspect of the present application provides a battery, comprising the positive electrode plate provided by the third aspect of the present application or the positive electrode active material provided by the first aspect of the present application.

[0143] As an example, the battery may be a lithium-ion battery or a sulfide solid-state battery.

[0144] The fifth aspect of the present application provides an electrical device, including the battery provided by the fourth aspect of the present application.

[0145] The electrical equipment may include 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., but are not limited thereto.

[0146] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the document in this area or the product specification are used. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained commercially.

[0147] Example 1

[0148] 1. Preparation of positive electrode active materials

[0149] Lanthanum salt LaCl3·7H2O, zirconium salt ZrOCl2·8H2O and M' salt AlCl3 are prepared into a first mixed solution, wherein La:Zr:Al in the first mixed solution is 2:2:0.04, and the concentration of metal elements in the first mixed solution is 2 mol / L, wherein the addition amount of dispersant PEG is 0.5%, and a 10 mol / L ammonia aqueous solution is prepared as a first complexing agent and precipitant solution, and a reaction base liquid is added into a reactor, wherein the reaction base liquid comprises ammonia water and dispersant PEG, the content of anhydrous chlorinated bicarbonate in the reaction base liquid is 3 g / L, and the pH value of the reaction base liquid is 10.1, and the temperature of the reactor is raised to 50°C, and the stirring speed is 700 rpm, and the first mixed solution, ammonia water and dispersant PEG are added into the reactor, and the pH value in the reaction system is controlled to be 10.1, the content of the complexing agent is 3 g / L, the reaction temperature is 50°C, the stirring speed is 700 rpm, and the total liquid addition time is 10 hours to obtain a slurry. The slurry was washed with 70°C pure water for 3 times, with the stirring speed of 500 rpm. After washing for 1 hour, the filter cake was obtained by suction filtration, and then dried at 200°C for 6 hours to obtain La2Zr2Al 0.04 (OH) 14.12 .

[0150] La2Zr2Al 0.04 (OH) 14.12 The first calcination was carried out by heating to 750°C at a rate of 5°C / min and sintering for 8h. After sand milling (the solvent was pure water, the sand milling time was 5h, and the slurry particle size D50 was 0.05μm), drying (spray drying inlet temperature 255°C, outlet temperature 100°C) and crushing (air flow crushing), the coating material C1 was obtained. The physical properties of C1 are shown in Table 1.

[0151] According to the metal elements, nickel salt (nickel sulfate), cobalt salt (cobalt sulfate) and manganese salt (manganese sulfate) are prepared into a second mixed solution with a concentration of 2 mol / L in a molar ratio of 93:3:4; M source (aluminum sulfate), second precipitant (sodium hydroxide) and second complexing agent (ammonia water) are 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;

[0152] The second mixed solution, M source solution, second precipitant solution and second complexing agent solution were added into a reactor, and coprecipitation reaction was carried out in an inert atmosphere (pH value was 11.2-11.8, temperature was 60°C), and a solid-liquid mixed slurry with a particle size D 50 4μm;

[0153] Wherein, the M source is added in an amount according to a molar ratio of [n(M)] / [n(Ni)+n(Co)+n(Mn)]=0.001;

[0154] The solid-liquid mixed slurry is filtered, washed, dried and sieved in sequence to obtain a slurry having the general formula [(Ni 0.93 Co 0.03 Mn 0.04 ) 0.999 Al 0.001 ](OH)2 multi-material precursor;

[0155] The above multi-material precursor, lithium source (lithium hydroxide) and M' source (zirconia, D 50 The surface area is 50 nm and the specific surface area is 100 m 2 / g) were mixed, calcined for the second time (temperature was 810°C, time was 12h), crushed and sieved to obtain a nickel-based multi-element material;

[0156] The lithium source is added in an amount according to a molar ratio of [n(Li)] / [n(Ni)+n(Co)+n(Mn)+n(M)+n(M')]=1.03; the M' source is added in an amount according to a molar ratio of [n(M')] / [n(Ni)+n(Co)+n(Mn)]=0.001; the general formula of the above nickel-based multi-element 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;

[0157] The nickel-based multi-element material as a matrix was mixed with the coating material at a mass ratio of 100:0.3 and calcined for the third time (temperature of 720° C., time of 8 h), crushed, and sieved to obtain a positive electrode active material.

[0158] 2. Preparation of positive electrode sheet

[0159] The positive electrode active material, acetylene black and polyvinylidene fluoride were dispersed in an appropriate amount of N-methylpyrrolidone (NMP) in a mass ratio of 95:2.5:2.5, coated on an aluminum foil and dried, and 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 hours and then vacuum sealed for storage.

[0160] 3. Negative electrode

[0161] A lithium metal sheet with a diameter of 16 mm and a thickness of 1 mm was used.

[0162] 4. Isolation film

[0163] Celgard porous membrane with a thickness of 25 μm.

[0164] 5. Electrolyte

[0165] LiPF6 was used as the solute, and equal volumes of ethylene carbonate, dimethyl carbonate and diethyl carbonate were used as solvents, and the concentration of LiPF6 was 1 mol / L.

[0166] 6.1 Assembling button cells

[0167] The positive electrode sheet, separator, negative electrode sheet and electrolyte were assembled into a 2025 button cell in a glove box filled with argon gas with a water content and an oxygen content of less than 5 ppm.

[0168] 6.2 Assembling Sulfide Solid-State Batteries

[0169] The positive electrode active material, acetylene black, polytetrafluoroethylene and Li 5.5 PS 4.5 Cl 1.5 The solid electrolyte was placed in a mortar and ground for 30 min at a mass ratio of 80:2:3:15 to achieve uniform mixing. 10 mg of the positive electrode active material was weighed and evenly dispersed on the bottom of a 10 mm diameter stainless steel mold. Then 150 mg of Li 5.5 PS 4.5 Cl 1.5 The solid electrolyte powder is poured into the mold, and finally a lithium negative electrode sheet with a diameter of 10 mm and a thickness of 1 mm is placed on it. It is pressed at a pressure of 600 MPa for 3 minutes to obtain a sandwich structured all-solid-state lithium-ion battery based on a sulfide solid electrolyte. Finally, the above battery is encapsulated in a 2025 battery case. The above processes are all carried out in a glove box filled with argon gas with a water content and an oxygen content of less than 5 ppm.

[0170] The preparation process of the batteries in Example 2 to Example 9, Comparative Example 2 and Comparative Example 3 is the same as that in Example 1, and the differences are detailed in Table 1 and Table 2.

[0171] Comparative Example 1

[0172] The preparation method of the battery is the same as that of Example 1, except that the preparation method of the coating material is:

[0173] According to the stoichiometric ratio of La2Zr2O7, lanthanum oxide and zirconium oxide were accurately weighed, mixed in a mixer at 850 rpm for 4 hours to make the raw materials fully mixed, and heated to 750°C at 5°C / min for the first calcination, and sintered for 8 hours. The subsequent sand grinding, drying and crushing were the same as in Example 1.

[0174] The preparation methods of the batteries of Examples 10 to 12, Comparative Examples 4 and 5 are the same as those of Example 3, and the differences are detailed in Table 2.

[0175]

[0176]

[0177] Performance Testing

[0178] 1. Half-width and peak intensity ratio of diffraction peak

[0179] The half-peak width and peak intensity ratio were obtained by Rigaku X-ray diffractometer.

[0180] 2.25℃ discharge specific capacity test method

[0181] The assembled 2025 button cell was placed in a constant temperature environment at 25°C for 24 hours, then charged to 4.3V at 0.1C on a charge and discharge tester, switched to constant voltage charging until the charging current was ≤0.01C, and then discharged to 3V at 0.1 discharge current, forming two cycles, and then repeated charging and discharging at 1C current. The charge and discharge capacity and cycle performance of the positive electrode active material in the liquid lithium-ion battery were investigated.

[0182] 3. Heat release test method

[0183] The assembled 2025 button battery was placed in a constant temperature environment of 25°C for 24 hours, then charged to 4.3V at a charging current of 0.1C on a charge and discharge tester, switched to constant voltage charging until the charging current was ≤0.01C, then discharged to 3V at a discharge current of 0.1, and finally charged to 4.3V at a charging current of 0.1C, switched to constant voltage charging until the charging current was ≤0.01C.

[0184] The fully charged 2025 button cell was disassembled in an argon-filled glove box with a water content and an oxygen content less than 5 ppm to obtain the positive electrode sheet, and then the positive electrode sheet was placed in a high-pressure crucible, sealed and taken out of the glove box, and finally tested on a METTLER TGA / DSC 3+ device. The specific conditions were 30°C-350°C, a heating rate of 5°C / min, an N2 atmosphere, and a carrier gas flow rate of 50 mL / min.

[0185] 4. Sulfide solid-state battery charge and discharge capacity

[0186] The sulfide solid-state battery is encapsulated in a 2025 battery shell. The above processes are all carried out in a glove box filled with argon gas with a water content and an oxygen content of less than 5ppm. The assembled 2025 sulfide solid-state battery is placed in a constant temperature environment of 25°C for 24 hours, and then charged to 4.3V at a charging current of 0.1C on a charge and discharge tester, switched to constant voltage charging to a charging current of ≤0.01C, and then discharged to 3V at a discharge current of 0.1C, forming 2 cycles. The charge and discharge capacity of the positive electrode active material in the sulfide solid-state battery is investigated.

[0187] The test results of the batteries in Examples 1 to 12 and Comparative Examples 1 to 5 are shown in Table 3.

[0188]

[0189]

[0190] From the comparison of Example 1 to Example 12 and Comparative Example 1 to Comparative Example 5 in Table 3, it can be seen that the present application can reduce the heat release peak of the positive electrode active material and improve the cycle performance of the battery by forming a coating material on the surface of the base material.

[0191] It can be seen from the comparison between Example 3, Comparative Example 2 and Comparative Example 3 that the temperature of the first calcination will affect the FWHM of the coating material. (222) Half-peak width: if the half-peak width of the coating material is too small, it indicates that the coating material is too crystalline and lacks sufficient surface activity; if the half-peak width 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.

[0192] It can be seen from the comparison between Example 3 and Comparative Example 5 that by controlling the temperature of the third calcination, a uniform coating material can be formed on the surface of the substrate, thereby inhibiting the release of active oxygen in the delithiation state of the substrate, preventing the multi-material from falling off and structural changes during repeated charge and discharge, and improving the cycle performance of the battery.

[0193] It can be seen from Examples 1 to 4 that by doping the coating material with ions with a radius greater than La 3+ Smaller elements or doping ions with a radius smaller than Zr 4+ Large elements can increase the oxygen vacancy defects, improve the adsorption of oxygen, and improve the ion and electron transmission of the coating material, thereby improving the capacity and cycle stability of the battery.

[0194] It can be seen from the comparison between Example 3, Example 5 and Example 8 that by adjusting the molar ratio of La element and Zr element, the content of the impurity phase 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.

[0195] It can be seen from Examples 6 and 9 that the I of the coating material can be adjusted by adjusting the temperature and heating rate of the first calcination. (222) / I (440) ratio, improves the uniformity of the crystal structure, exhibits a better oxygen adsorption effect, and thus inhibits the side reaction between the de-lithium positive electrode material and the electrolyte, thereby improving the cycle performance of the battery.

[0196] It can be seen from the comparison between Example 3 and Example 7 that by controlling the median particle size D of the coating material after air flow crushing 50 , the average particle size of the coating material on the substrate surface can be controlled, thereby adjusting the battery's cycle performance and heat release peak, and improving the battery's safety performance.

[0197] It can be seen from the comparison of Example 3, Example 11, Example 12 and Comparative Example 4 that by controlling the content of the substrate surface coating material, the capacity and heat release peak of the battery can be optimized to obtain a battery with both higher capacity and lower heat release peak.

[0198] By the attached Figure 2 It can be seen that the coating materials prepared in Examples 1 to 3 of the present application can regulate the grain size and half-peak width through doping, accelerate the reaction rate, and improve the ionic conductivity and charge transfer efficiency.

[0199] By the attached Figure 3 It can be seen that the primary particles of the coating material are between 50nm and 100nm and have good dispersion. These particles can provide more reaction sites and significantly improve efficiency and performance.

[0200] By the attached Figure 4 It can be seen that a discontinuous coating material is formed on the surface of the matrix material. The particle size of the coating material is about 50nm. After coating, it can improve the ionic and electronic conductivity, give full play to the capacity of the positive electrode active material, and improve the battery energy density; it can also adsorb and store the active oxygen of the highly delithiated matrix material, inhibit the side reaction between the positive electrode and the electrolyte, and improve the battery cycle life.

[0201] By the attached Figure 5 It can be seen that the surface of the base material prepared in Comparative Example 1 is smooth and no coating material is formed.

[0202] The description of "an embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0203] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A positive electrode active material, characterized in that: include: A matrix, wherein 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, 0.9≤x≤1.3, 0.02≤i≤0.2, 0<j≤0.2, 0.002<p≤0.1; A coating material, the coating material is located on at least a portion of the surface of the substrate, and the coating material includes a compound shown in 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, 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, 5≤ε≤10; In the X-ray diffraction pattern of the coating material, the half-peak width of the diffraction peak (222) is FWHM (222) , and satisfy: 0.3≤FWHM (222) ≤0.

53.

2. The positive electrode active material according to claim 1, characterized in that Based on the total mass of the substrate, the mass proportion of the coating material is 0.05%-2%, and can be optionally 0.1%-0.5%.

3. The positive electrode active material according to claim 1 or 2, characterized in that: In the X-ray diffraction spectrum of the coating material, the ratio of the peak intensity of the diffraction peak (222) to the peak intensity of the diffraction peak (440) satisfies: 2.8≤I (222) / I (440) ≤3.

5.

4. The positive electrode active material according to claim 1 or 2, characterized in that: The proportion of the heterogeneous phase in the crystal structure of the coating material is less than or equal to 2%. Optionally, the proportion of the heterogeneous phase in the crystal structure of the coating material is less than or equal to 1.5%.

5. The positive electrode active material according to claim 1 or 2, characterized in that: Satisfy at least one of the following conditions: The average particle size D of the matrix 50 1.2μm-6.2μm, preferably, D 50 2.2μm-4.5μm; The average particle size of the coating material is 10nm-100nm.

6. A method for preparing the positive electrode active material according to any one of claims 1 to 5, characterized in that: include: The lanthanum source, zirconium source, M source, M' source, the first precipitant, the first complexing agent, and the first solvent are mixed to perform the first coprecipitation and dried 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 first calcined to obtain a coating material, wherein the temperature of the first calcination is 700° C.-910° C.; Mixing a nickel source, a cobalt source, a manganese source, a second precipitant, a second complexing agent, and a second solvent to perform a second co-precipitation to obtain a multi-material precursor; The multi-material precursor, lithium source and M" source are mixed and calcined for the second time to obtain the multi-material, and the temperature of the second calcination is 650°C-1000°C; The multi-material and the coating material are mixed and calcined for a third time to obtain the positive electrode active material. The temperature of the third calcination is 600° C.-900° C.

7. The method according to claim 6, characterized in that The temperature of the third calcination is 650°C-850°C; and / or The third calcination time is 4h-48h, and can be optionally 8h-24h.

8. The method according to claim 6, characterized in that When the multi-material and the coating material are mixed, the mass of the coating material is m1, the mass of the multi-material is m2, and 0.01%≤m1 / m2≤5% is satisfied, and optionally, 0.1%≤m1 / m2≤2%.

9. The method according to claim 6, characterized in that Satisfy at least one of the following conditions: The heating rate of the first calcination is 0.5°C / min-10°C / min, and can be optionally 1°C / min-5°C / min; The first calcination time is 5h-24h, and can be 8h-18h; The temperature of the second calcination is 750°C-900°C; The second calcination time is 4h-48h, and can be optionally 8h-24h.

10. The method according to claim 6, characterized in that Satisfy at least one of the following conditions: The particle size Dv50 of the multi-element material is 2 μm-20 μm, and can be optionally 3 μm-15 μm; The specific surface area of ​​the multi-component material is 0.2 m 2 / g-1.2m 2 / g, optional 0.4m 2 / g-1m 2 / g.

11. The method according to claim 6, characterized in that Satisfy at least one of the following conditions: The pH value of the first coprecipitation is 7.5-11.5, and the temperature is 30° C.-55° C.; The pH value of the second co-precipitation is 10-13, and the temperature is 40°C-80°C.

12. A positive electrode sheet, characterized in that: The invention comprises the positive electrode active material described in any one of claims 1 to 5 or the positive electrode active material prepared by the method described in any one of claims 6 to 11.

13. A battery, characterized in that: The invention comprises the positive electrode sheet according to claim 12 or the positive electrode active material according to any one of claims 1 to 5.

14. An electrical device, characterized in that: Comprising the battery of claim 13.

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