Rich nickel cathode material, its preparation method, cathode electrode sheet, lithium-ion battery, and electricity-related equipment

Abstract

The present application provides a nickel-rich cathode material, a preparation method thereof, a cathode electrode sheet, a lithium-ion battery, and an electricity-related device, relating to the field of new energy technologies. The nickel-rich cathode material provided by the present application adopts a cation-anion coupling co-doping strategy. The doping of N element in the anion can improve the atomic vacancies generated during the sintering process, re-arrange the charges in the unit cell structure by increasing the vacancy concentration of the electron positions in the energy band gap, adjust the proportion of Ni elements with different valence states in the nickel-rich cathode material, increase the proportion of Ni<supgt;3+< / supgt;, and thereby improve the material capacity. At the same time, by introducing cation doping, in the way of occupying the Ni<supgt;2+< / supgt; site or increasing the unit cell layer spacing, the primary particles are regulated, the particle density and growth consistency are increased, the Li<supgt;+< / supgt; transport channel is broadened, the unit cell structure is stabilized, the migration barrier of Ni<supgt;2+< / supgt; and the dissipation barrier of O are increased, the lithium-ion diffusion coefficient and kinetic performance are improved, and the severity of the internal volume stress change of the primary particles of the material is slowed down.

Description

Technical Field

[0001] This application relates to the field of new energy technologies, and particularly to a nickel-rich cathode material, a preparation method thereof, a cathode electrode sheet, a lithium-ion battery, and an electricity-related device. Background Art

[0002] The cathode material of a lithium-ion battery is crucial for its energy density, thermal stability, service life, and cost. Nickel-rich layered oxides such as LiNi x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y O2 (x≥0.8) etc. have received extensive attention due to their reasonable cost and high energy density. Increasing the Ni ratio is the most effective way to further improve the energy density of the battery and reduce production costs at present. However, with the increase of the Ni content in the nickel-rich layered oxide, the cycle stability and thermal stability of the cathode material will also deteriorate. Summary of the Invention

[0003] The purpose of this application is to provide a nickel-rich cathode material, a preparation method thereof, a cathode electrode sheet, a lithium-ion battery, and an electricity-related device, aiming to solve the problem that the cycle stability and thermal stability of the cathode material deteriorate with the increase of the Ni content in the existing nickel-rich layered oxide.

[0004] To achieve the above purpose, this application provides a nickel-rich cathode material, which includes a core and a coating layer covering the core. The core is doped with N element and cation elements, and the coating layer includes N element and cation elements; the chemical general formula of the nickel-rich cathode material is LiNi x Co y Mn z Al 1-x-y-z C c D d N n O2; wherein, 0.80≤x≤0.95, 0≤y≤0.10, 0≤z≤0.10, C is the cation element doped in the core, 0.10≤c≤0.30, D is the cation element in the coating layer, 0.10≤d≤0.20, n≤0.45.

[0005] In some embodiments, the cation elements doped in the core include at least one of Zr, Sr, Y, Al, B, Mg, Nb, Mo;

[0006] The cation elements in the coating layer include at least one of Al, W, Ti, Ce, Co, Ta, Er.

[0007] In some embodiments, at least one of the following conditions is satisfied:

[0008] (1) The thickness of the coating layer is 1 to 3 nm;

[0009] (2) The D50 of the nickel-rich cathode material is 9.0 μm to 13.5 μm;

[0010] (3) The specific surface area of the nickel-rich cathode material is 0.25 to 0.80 m 2 / g;

[0011] (4) The tap density of the nickel-rich cathode material is ≥ 2.2 g / cm 3 ; Optionally, the tap density of the nickel-rich cathode material is 2.2 to 2.8 g / cm 3 ;

[0012] (5) The intensity ratio of the 003 / 104 diffraction peaks in the XRD characteristic peaks of the nickel-rich cathode material is ≥ 1.30; Optionally, the intensity ratio of the 003 / 104 diffraction peaks in the XRD characteristic peaks of the nickel-rich cathode material is 1.30 to 1.45;

[0013] (6) The nickel-rich cathode material is a spherical secondary particle composed of stacked primary particles;

[0014] (7) Under the condition of satisfying (6), the length of the primary particle is 300 to 500 nm;

[0015] (8) Under the condition of satisfying (6), the aspect ratio of the primary particle is between 1.5 and 3.0.

[0016] This application also provides a preparation method of the above nickel-rich cathode material, including:

[0017] First, mix the nickel-rich cathode material precursor and the lithium source, and add a first biphasic coupling initiator during the first mixing process to obtain a first mixture;

[0018] First sinter the first mixture to obtain a material to be coated;

[0019] Second, mix the material to be coated, and add a second biphasic coupling initiator during the second mixing process to obtain a second mixture;

[0020] Second sinter the second mixture to obtain the nickel-rich cathode material;

[0021] Among them, both the first biphasic coupling initiator and the second biphasic coupling initiator include anionic elements and cationic elements, and the anionic element is N.

[0022] In some embodiments, first mixing the nickel-rich cathode material precursor and the lithium source, and adding a first biphasic coupling initiator during the first mixing process includes:

[0023] During the first mixing process of the nickel-rich cathode material precursor and the lithium source, spray the first biphasic coupling initiator after ultrasonic atomization, and perform microwave drying to obtain the first mixture;

[0024] And / or, perform a second mixing on the material to be coated, and add the second biphasic coupling initiator during the second mixing process, including:

[0025] During the second mixing process of the material to be coated, spray the second biphasic coupling initiator after ultrasonic atomization, and perform microwave drying to obtain the second mixture.

[0026] In some embodiments, the processes of the first mixing and the second mixing both include: a first stage, a second stage, and a third stage in which the mixing speed increases successively; and satisfy at least one of the following conditions:

[0027] A. The rotation speed in the first stage is 50 - 400 r / min, and the time is 1 - 5 min;

[0028] B. The rotation speed in the second stage is 100 - 600 r / min, and the time is 2 - 10 min;

[0029] C. The rotation speed in the third stage is 400 - 1000 r / min, and the time is 10 - 20 min;

[0030] D. Both the first biphasic coupling initiator after ultrasonic atomization and the second biphasic coupling initiator after ultrasonic atomization are sprayed in the second stage;

[0031] E. The spraying rate of the first biphasic coupling initiator after ultrasonic atomization and the second biphasic coupling initiator after ultrasonic atomization is 10 - 50 mL / min;

[0032] F. The microwave drying is both carried out in the third stage;

[0033] G. The power of the microwave drying is 8 - 15 kW, and the temperature is 50 - 80 °C.

[0034] In some embodiments, satisfy at least one of the following conditions:

[0035] A. Based on the mass of the nickel-rich cathode material precursor, the addition amount of the first biphasic coupling initiator is 1000 - 3000 ppm;

[0036] B. Based on the mass of the material to be coated, the addition amount of the second biphasic coupling initiator is 1000 - 2000 ppm;

[0037] C. Both the first biphasic coupling initiator and the second biphasic coupling initiator are secondary particles composed of primary particles, the particle size of the primary particles ≤ 30 nm, and the particle size of the secondary particles is 1 μm - 3 μm;

[0038] D. The cationic elements of the first biphasic coupling initiator include at least one of Zr, Sr, Y, Al, B, Mg, Nb, and Mo; the cationic elements of the second biphasic coupling initiator include at least one of Al, W, Ti, Ce, Co, Ta, and Er;

[0039] E. The first sintering includes: continuously introducing oxygen, heating from room temperature to 450 °C at a heating rate of 5 °C / min and holding for 2 h, then heating to 600 °C at a heating rate of 1 °C / min and holding for 2 h, and then heating to 700 - 800 °C at a heating rate of 2 °C / min and holding for 10 - 15 h;

[0040] F. The second sintering includes: heating from room temperature to 500 - 700 °C at a heating rate of 2 °C / min and holding for 6 - 12 h;

[0041] G. The chemical general formula of the nickel-rich cathode material precursor is: Ni x Co y Mn z Al 1-x-y-z (OH)2, where 0.80 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.10, and 0 ≤ z ≤ 0.10;

[0042] H. The particle size D50 of the lithium source is 1 μm to 5 μm;

[0043] I. The lithium source is selected from any one of LiOH, Li2CO3, CH3COOLi, and Li2C2O4.

[0044] The present application also provides a positive electrode sheet including the above nickel-rich cathode material.

[0045] The present application also provides a lithium-ion battery including the above positive electrode sheet.

[0046] The present application also provides an electricity-related device including the above lithium-ion battery.

[0047] Compared with the prior art, the beneficial effects of the present application include:

[0048] The nickel-rich cathode material provided by the present application adopts a cation-anion coupling co-doping strategy. The doping of N element in the anion can improve the atomic vacancies generated during the sintering process, re-arrange the charges in the unit cell structure by increasing the vacancy concentration of electrons in the energy level band gap, adjust the ratio of Ni elements with different valence states in the nickel-rich cathode material, and increase the proportion of Ni 3+ thereby improving the material capacity; at the same time, by introducing cation doping to occupy Ni 2+By means of increasing the interlayer spacing of the unit cell, regulating the primary particles, increasing the particle density and growth consistency, and broadening the Li + transport channels, stabilizing the unit cell structure, and increasing the Ni 2+ migration barrier and the O dissipation barrier, improving the lithium ion diffusion coefficient and kinetic performance, and slowing down the severity of the internal volume stress change of the primary particles of the material. In addition, after introducing cations into the material, by regulating the doping ratio of anions and cations, balancing the internal charge, and adjusting the Ni 2+ / Ni 3+ ratio, the optimal Li / Ni mixing state is achieved inside the material, improving the electrochemical performance of the material.

[0049] The nickel-rich cathode material provided by this application constructs a dual-phase state of a high-entropy material surface - low-entropy material interior on the surface through the co-coating of N element and cationic metal elements. The shielding effect of high entropy is used to reduce the dissolution of transition metals, inhibit the catalytic effect of transition metals on the electrolyte, improve the structural stability of the CEI film, slow down the epitaxial growth of the CEI film, stabilize the median voltage, and effectively reduce the interfacial impedance of the cathode material.

[0050] In order to avoid the problem of poor kinetics in the gas-solid two-phase reaction, the preparation method of the nickel-rich cathode material provided by this application provides a strategy of ultrasonic atomization and microwave radiation-assisted drying to introduce the dual-phase coupling initiator into the interior and surface of the primary particles of the cathode material in the form of liquid-solid dispersion. The distribution of low-entropy phase elements inside is uniform, and the orientation of primary particles is consistent, greatly alleviating the damage to the interior of the material caused by volume anisotropic stress. The high-entropy phase restricts surface reconstruction, slows down element dissolution and harmful substance erosion, and uses dual-phase coupling to improve the various performances of the nickel-rich cathode material. Description of the Drawings

[0051] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope of this application.

[0052] Figure 1 SEM image of the nickel-rich cathode material of Example 1;

[0053] Figure 2 SEM image of the nickel-rich cathode material of Example 2;

[0054] Figure 3 SEM image of the nickel-rich cathode material of Example 3;

[0055] Figure 4 SEM image of the nickel-rich cathode material of Example 4;

[0056] Figure 5Scanning electron microscope image of the nickel-rich cathode material of Example 5;

[0057] Figure 6 Scanning electron microscope image of the nickel-rich cathode material of Example 6;

[0058] Figure 7 Scanning electron microscope image of the nickel-rich cathode material of Example 7;

[0059] Figure 8 Scanning electron microscope image of the nickel-rich cathode material of Example 8;

[0060] Figure 9 Scanning electron microscope image of the nickel-rich cathode material of Comparative Example 1;

[0061] Figure 10 Scanning electron microscope image of the nickel-rich cathode material of Comparative Example 2;

[0062] Figure 11 Scanning electron microscope image of the nickel-rich cathode material of Comparative Example 3;

[0063] Figure 12 Scanning electron microscope image of the nickel-rich cathode material of Comparative Example 4;

[0064] Figure 13 Initial electrochemical charge-discharge curves of Example 4, Example 7 and Comparative Examples 1 to 4;

[0065] Figure 14 Schematic flow chart of the preparation method of the nickel-rich cathode material of the present application. Detailed implementation manners

[0066] As used herein, the terms:

[0067] "Prepared from" is synonymous with "comprising". As used herein, the terms "comprising", "including", "having", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or apparatus containing the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or apparatus.

[0068] The connecting phrase "consisting of" excludes any unstated element, step or component. If used in a claim, this phrase will render the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the claim body rather than immediately following the subject, it only limits the elements described in that clause; other elements are not excluded from the claim as a whole.

[0069] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed individually. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include ranges such as "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0070] In these examples, unless otherwise specified, the parts and percentages are by mass.

[0071] "Parts by mass" refers to the basic measurement unit representing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1 g or 2.689 g, etc. If we say that the mass part of component A is a parts and the mass part of component B is b parts, it means the mass ratio of component A to component B is a:b. Or, it means the mass of component A is aK and the mass of component B is bK (K is any number representing a multiple factor). It should not be misunderstood that, different from the number of mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0072] "And / or" is used to indicate that either or both of the stated situations may occur. For example, A and / or B includes (A and B) and (A or B).

[0073] This application provides a nickel-rich cathode material, including a core and a coating layer coating the core. The core is doped with N element and cation elements, and the coating layer includes N element and cation elements; the chemical general formula of the nickel-rich cathode material is LiNi x Co y Mn z Al 1-x-y-z C c D d N nO2; where 0.80 ≤ x ≤ 0.95, and x can be, for example, 0.80, 0.85, 0.86, 0.88, 0.90, 0.91, 0.92, 0.93, 0.95 or any value between 0.80 and 0.95; 0 ≤ y ≤ 0.10, 0 ≤ z ≤ 0.10, and y and z can be, for example, 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10 or any value between 0 and 0.10; C is a cationic element doped in the core, 0.10 ≤ c ≤ 0.30, and c can be, for example, 0.10, 0.12, 0.15, 0.17, 0.18, 0.19, 0.20, 0.22, 0.25, 0.27, 0.30 or any value between 0.10 and 0.30; D is a cationic element in the coating layer, 0.10 ≤ d ≤ 0.20, and d can be, for example, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20 or any value between 0.10 and 0.20; n ≤ 0.45, and n can be, for example, 0.1, 0.2, 0.3, 0.40, 0.45 or any value ≤ 0.45; where c, d and n are all mass percentage contents.

[0074] The nickel-rich cathode material provided by this application adopts an anion-cation coupling co-doping strategy. The doping of N element in the anion can improve the atomic vacancies generated during the sintering process. By increasing the vacancy concentration of electrons in the energy level bandgap, the charge within the unit cell structure is rearranged, adjusting the proportion of Ni elements with different valence states in the nickel-rich cathode material and increasing the proportion of Ni 3+ to improve the material capacity. At the same time, by introducing cation doping, in the way of occupying the Ni 2+ site or increasing the unit cell layer spacing, the primary particles are regulated, the particle density and growth consistency are increased, the Li + transport channels are broadened, the unit cell structure is stabilized, the Ni 2+ migration barrier and the O dissipation barrier are increased, the lithium ion diffusion coefficient and kinetic performance are improved, and the severity of the internal volume stress change of the primary particles of the material is slowed down. In addition, after introducing cations into the material, by regulating the doping ratio of anions and cations, the internal charge is balanced, the Ni 2+ / Ni 3+ ratio is adjusted to achieve the optimal Li / Ni mixed arrangement state inside the material and improve the electrochemical performance of the material.

[0075] The nickel-rich cathode material provided by this application constructs a dual-phase state of a high-entropy material surface and a low-entropy material interior by co-coating with N element and cationic metal elements on the surface, uses the shielding effect of high entropy to reduce the dissolution of transition metals, inhibits the catalytic effect of transition metals on the electrolyte, improves the structural stability of the CEI film, slows down the epitaxial growth of the CEI film, stabilizes the median voltage, and effectively reduces the interfacial impedance of the cathode material.

[0076] In some embodiments, the cationic elements doped in the core include at least one of Zr, Sr, Y, Al, B, Mg, Nb, and Mo;

[0077] The cationic elements in the coating layer include at least one of Al, W, Ti, Ce, Co, Ta, and Er.

[0078] In some embodiments, the thickness of the coating layer is 1-3 nm, for example, it can be 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm or any value between 1-3 nm; the D50 of the nickel-rich cathode material is 9.0 μm-13.5 μm, for example, it can be 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm, 12.0 μm, 12.5 μm, 13.0 μm, 13.5 μm or any value between 9.0 μm-13.5 μm.

[0079] In some embodiments, the specific surface area of the nickel-rich cathode material is 0.25-0.80 m 2 / g, for example, it can be 0.25 m 2 / g, 0.30 m 2 / g, 0.35 m 2 / g, 0.40 m 2 / g, 0.45 m 2 / g, 0.50 m 2 / g, 0.55 m 2 / g, 0.60 m 2 / g, 0.65 m 2 / g, 0.70 m 2 / g, 0.75 m 2 / g, 0.80 m 2 / g or any value between 0.25-0.80 m 2 / g.

[0080] In some embodiments, the tap density of the nickel-rich cathode material is ≥2.2 g / cm 3 , for example, it can be 2.2 g / cm 3 , 2.3 g / cm 3 , 2.4 g / cm 3 , 2.5 g / cm 3, 2.6 g / cm 3 , 2.7 g / cm 3 , 2.8 g / cm 3 , 2.9 g / cm 3 , 3.0 g / cm 3 , 3.1 g / cm 3 , 3.2 g / cm 3 or ≥ 2.2 g / cm 3 Any value of. Optionally, the tap density of the nickel-rich cathode material is 2.2 - 2.8 g / cm 3 .

[0081] In some embodiments, the intensity ratio of the 003 / 104 diffraction peaks in the XRD characteristic peaks of the nickel-rich cathode material is ≥ 1.30. Optionally, the intensity ratio of the 003 / 104 diffraction peaks in the XRD characteristic peaks of the nickel-rich cathode material is 1.30 - 1.45. For example, it can be 1.30, 1.33, 1.35, 1.39, 1.41, 1.43, 1.45 or any value between 1.30 - 1.45.

[0082] In some embodiments, the nickel-rich cathode material is a quasi-spherical secondary particle composed of stacked primary particles; the length of the primary particle is 300 - 500 nm. For example, the length can be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or any value between 300 - 500 nm; the aspect ratio of the primary particle is between 1.5 - 3.0. For example, the aspect ratio can be 1.5, 2.0, 2.5, 3.0 or any value between 1.5 - 3.0.

[0083] This application also provides a preparation method of the above nickel-rich cathode material. Please refer to Figure 14 , including:

[0084] S100: First mix the nickel-rich cathode material precursor and the lithium source, and add the first biphasic coupling initiator during the first mixing process to obtain the first mixture;

[0085] S200: First sinter the first mixture to obtain the material to be coated;

[0086] S300: Second mix the material to be coated, and add the second biphasic coupling initiator during the second mixing process to obtain the second mixture;

[0087] S400: Second sinter the second mixture to obtain the nickel-rich cathode material.

[0088] Among them, both the first biphasic coupling initiator and the second biphasic coupling initiator include anionic elements and cationic elements, and the anionic element is N.

[0089] In some embodiments, step S100 performs a first mixing of the nickel-rich cathode material precursor and the lithium source, and adds a first biphasic coupling initiator during the first mixing process, including:

[0090] During the first mixing of the nickel-rich cathode material precursor and the lithium source, the ultrasonically atomized first biphasic coupling initiator is sprayed in, and microwave drying is performed to obtain a first mixture.

[0091] In some embodiments, step S300 performs a second mixing of the material to be coated, and adds a second biphasic coupling initiator during the second mixing process, including:

[0092] During the second mixing of the material to be coated, the ultrasonically atomized second biphasic coupling initiator is sprayed in, and microwave drying is performed to obtain a second mixture.

[0093] The preparation method of the nickel-rich cathode material provided by the present application aims to avoid the problem of poor kinetics in the gas-solid two-phase reaction, and provides a strategy of ultrasonic atomization and microwave radiation-assisted drying to introduce the biphasic coupling initiator into the interior and surface of the primary particles of the cathode material in the form of liquid-solid dispersion. The low-entropy phase elements inside are evenly distributed, the primary particles have a consistent orientation, greatly alleviating the damage to the interior of the material caused by volume anisotropic stress. The high-entropy phase restricts surface reconstruction, slows down element dissolution and harmful substance erosion, and uses biphasic coupling to improve the various properties of the nickel-rich cathode material.

[0094] In some embodiments, the processes of the first mixing in step S100 and the second mixing in step S300 both include: a first stage, a second stage, and a third stage in which the mixing rotation speed increases successively. The rotation speed in the first stage is 50 - 400 r / min, for example, it can be 50 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, or any value between 50 - 400 r / min, and the time is 1 - 5 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, or any value between 1 - 5 min. The rotation speed in the second stage is 100 - 600 r / min, for example, it can be 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, or any value between 100 - 600 r / min, and the time is 2 - 10 min, for example, it can be 2 min, 3 min, 5 min, 8 min, 10 min, or any value between 2 - 10 min. The rotation speed in the third stage is 400 - 1000 r / min, for example, it can be 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, or any value between 400 - 1000 r / min, and the time is 10 - 20 min, for example, it can be 10 min, 12 min, 13 min, 15 min, 17 min, 18 min, 20 min, or any value between 10 - 20 min.

[0095] In some embodiments, both the first biphasic coupling initiator after ultrasonic atomization and the second biphasic coupling initiator after ultrasonic atomization are sprayed in the second stage. The first biphasic coupling initiator and the second biphasic coupling initiator can both be ultrasonically atomized by dissolving in a solvent; and the spraying rate is 10 - 50 mL / min, for example, it can be 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, or any value between 10 - 50 mL / min.

[0096] In some embodiments, microwave drying is carried out in the third stage. Microwave drying can evaporate the solvents of the first biphasic coupling initiator and the second biphasic coupling initiator, preventing the materials from getting damp and caking, which may affect the subsequent steps. The power of microwave drying is 8 - 15 kW, and the temperature is 50 - 80 °C.

[0097] In some embodiments, based on the mass of the nickel-rich cathode material precursor, the addition amount of the first biphasic coupling initiator is 1000 - 3000 ppm. For example, it can be 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 2000 ppm, 2200 ppm, 2500 ppm, 2700 ppm, 3000 ppm, or any value between 1000 - 3000 ppm.

[0098] In some embodiments, based on the mass of the material to be coated, the addition amount of the second biphasic coupling initiator is 1000 - 2000 ppm. For example, it can be 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, or any value between 1000 - 2000 ppm.

[0099] In some embodiments, both the first biphasic coupling initiator and the second biphasic coupling initiator are secondary particles composed of primary particles. The particle size of the primary particles ≤ 30 nm, and the particle size of the secondary particles is 1 μm - 3 μm.

[0100] In some embodiments, the cationic elements of the first biphasic coupling initiator include at least one of Zr, Sr, Y, Al, B, Mg, Nb, and Mo; the cationic elements of the second biphasic coupling initiator include at least one of Al, W, Ti, Ce, Co, Ta, and Er.

[0101] In some embodiments, the first sintering in step S200 includes: continuously introducing oxygen, heating from room temperature to 450 °C at a heating rate of 5 °C / min and holding for 2 h, then heating to 600 °C at a heating rate of 1 °C / min and holding for 2 h, and then heating to 700 - 800 °C at a heating rate of 2 °C / min and holding for 10 - 15 h.

[0102] In some embodiments, the second sintering in step S400 includes: heating from room temperature to 500 - 700 °C at a heating rate of 2 °C / min and holding for 6 - 12 h.

[0103] In some embodiments, the chemical general formula of the nickel-rich cathode material precursor is: Ni x Co y Mn z Al 1-x-y-z (OH)2, where 0.80 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.10, and 0 ≤ z ≤ 0.10.

[0104] In some embodiments, the particle size D50 of the lithium source is 1 μm to 5 μm. The lithium source is selected from any one of LiOH, Li2CO3, CH3COOLi, and Li2C2O4.

[0105] The present application also provides a positive electrode sheet, including the above-mentioned nickel-rich cathode material.

[0106] The present application also provides a lithium-ion battery, including the above-mentioned positive electrode sheet.

[0107] The present application also provides an electricity-related device, including the above-mentioned lithium-ion battery.

[0108] The following will describe the implementation scheme of the present application in detail with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0109] Example 1

[0110] Disperse and mix 53 g of the nano-biphasic coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water in a ratio of 1:3 (mass ratio) to obtain a mixed solution A. Add 2.37 kg of lithium hydroxide and 5 kg of the nickel-rich precursor Ni 0.90 Mn 0.10 (OH)2 to a high-speed mixer for mixing. Ultrasonically atomize the mixed solution A and spray it into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage ends, transfer to the high-speed mixing stage, and at the same time turn on microwave radiation drying to obtain material B.

[0111] After the mixing is completed, discharge material B, load it into a crucible, transfer it into a kiln, and introduce oxygen (≥90%) for sintering. Set the program for temperature rise and fall. Finally, set the temperature in the constant temperature section to 735 °C. After the constant temperature sintering is completed, stop introducing oxygen and switch to introducing N2. After cooling to room temperature, take out the material, and obtain the material C to be coated after pulverization, washing, and centrifugal drying.

[0112] Take 10 g of the nano-biphasic coupling initiator CeN (1500 ppm) and 30 g of deionized water and disperse and mix them in a ratio of 1:3 (mass ratio) to obtain a mixed solution D. Spray the mixed solution D into 5 kg of the material C to be coated at the same rate in the medium-speed stage. The subsequent mixing process is the same as the raw material mixing process.

[0113] After mixing, transfer the material to a kiln. Set the program for temperature rise and fall and introduce oxygen (≥90%) for sintering. Set the constant temperature to 680 °C. After the heat preservation is completed, cool it to room temperature in the furnace to obtain the cathode material LiNi with dual-phase coupling modification of anions and cations in Example 1 0.90 Mn 0.10 B 0.25 Ce 0.15 N 0.35 O2. Among them, in CeN with a coating amount of 1500 ppm, the coating amount of N element is about 100 ppm, which is basically undetectable. Therefore, the amount of N element in the cathode material is basically the doping amount in the core. The following examples and comparative examples are similar

[0114] Example 2

[0115] Disperse and mix 53 g of nano dual-phase coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water in a ratio of 1:3 (mass ratio) to obtain mixture A. Mix 2.35 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.88 Co 0.09 Al 0.03 (OH)2 in a high-speed mixer. Ultrasonically atomize mixture A and spray it into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage is completed, transfer to the high-speed mixing stage and turn on microwave radiation drying simultaneously to obtain material B

[0116] After mixing, discharge material B, place it in a crucible, transfer it to a kiln, introduce oxygen (≥95%) for sintering, set the program for temperature rise and fall, and finally set the temperature in the constant temperature section to 725 °C. After the constant temperature sintering is completed, stop introducing oxygen and switch to introducing N2. After cooling to room temperature, take out the material, and obtain the material to be coated C after crushing, washing, centrifuging and drying

[0117] Take 10 g of nano dual-phase coupling initiator CeN (1500 ppm) and 30 g of deionized water, disperse and mix them in a ratio of 1:3 (mass ratio) to obtain mixture D. Spray mixture D into 5 kg of material to be coated C at the same rate in the medium-speed stage. The subsequent mixing process is the same as the raw material mixing process

[0118] After mixing, transfer the material to a kiln. Set the program for temperature rise and fall and introduce oxygen (≥90%) for sintering. Set the constant temperature to 680 °C. After the heat preservation is completed, cool it to room temperature in the furnace to obtain the cathode material LiNi with dual-phase coupling modification of anions and cations in Example 2 0.88 Co 0.09 Al 0.03 B 0.25 Ce 0. 15 N 0.35O2。

[0119] Example 3

[0120] Disperse and mix 53 g of nano-biphase coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water in a ratio of 1:3 (mass ratio) to obtain mixture A. Add 2.38 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.85 Co 0.10 Mn 0.05 (OH)2 to a high-speed mixer for mixing. Ultrasonically atomize mixture A and spray it into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage ends, transfer to the high-speed mixing stage and simultaneously turn on microwave radiation drying to obtain material B.

[0121] After the mixing is completed, discharge material B, place it in a sagger, transfer it to a kiln, and sinter it by introducing oxygen (≥90%). Set the program for temperature rise and fall, and finally set the temperature in the constant-temperature section to 760 °C. After the constant-temperature sintering is completed, stop introducing oxygen and switch to introducing N2. After cooling to room temperature, take out the material, and obtain the material C to be coated after crushing, washing with water, and centrifugal drying.

[0122] Take 10 g of nano-biphase coupling initiator CeN (1500 ppm) and 30 g of deionized water, disperse and mix them in a ratio of 1:3 (mass ratio) to obtain mixture D. Spray mixture D into 5 kg of material C to be coated at the same rate in the medium-speed stage. The subsequent mixing process is the same as the raw material mixing process.

[0123] After the mixing is completed, transfer the material to a kiln, set the program for temperature rise and fall, and sinter it by introducing oxygen (≥90%). Set the constant-temperature temperature to 680 °C. After the heat preservation is completed, cool it to room temperature with the furnace to obtain the cathode material LiNi 0.85 Co 0.10 Al 0.05 B 0.25 Ce 0.15 N 0.35 O2.

[0124] Example 4

[0125] Disperse and mix 53 g of nano-biphase coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water in a ratio of 1:3 (mass ratio) to obtain mixture A. Add 2.35 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.90 Co 0.06 Mn 0.04(OH)2 is added to a high-speed mixer for mixing. The mixed liquid A is ultrasonically atomized and sprayed into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage ends, it is transferred to the high-speed mixing stage, and at the same time, microwave radiation drying is started to obtain material B.

[0126] After the mixing is completed, material B is discharged, placed in a sagger and transferred into a kiln. Oxygen (≥95%) is introduced for sintering. The temperature is set to rise and fall according to a program. The final constant temperature is set at 750 °C. After the constant temperature sintering is completed, the oxygen supply is stopped and N2 is introduced instead. After cooling to room temperature, the material is taken out and obtained as the material C to be coated after being crushed, washed with water, centrifuged and dried.

[0127] 10 g of nano-biphasic coupling initiator CeN (1500 ppm) and 30 g of deionized water are dispersed and mixed in a ratio of 1:3 (mass ratio) to obtain mixed liquid D. Mixed liquid D is sprayed into 5 kg of material C to be coated at the same rate in the medium-speed stage. The subsequent mixing process is the same as that of the raw material mixing process.

[0128] After the mixing is completed, the material is transferred to a kiln. The temperature is set to rise and fall according to a program while oxygen (≥90%) is introduced for sintering. The constant temperature is set at 680 °C. After the heat preservation is completed, it is cooled to room temperature with the furnace to obtain the cathode material LiNi 0.90 Co 0.06 Mn 0.04 B 0.25 Ce 0.15 N 0.35 O2.

[0129] Example 5

[0130] 53 g of nano-biphasic coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water are dispersed and mixed in a ratio of 1:3 (mass ratio) to obtain mixed liquid A. According to a ratio of 1.045:1.0 (molar ratio), 2.38 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.92 Co 0.03 Mn 0.03 Al 0.02 (OH)2 is added to a high-speed mixer for mixing. The mixed liquid A is ultrasonically atomized and sprayed into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage ends, it is transferred to the high-speed mixing stage, and at the same time, microwave radiation drying is started to obtain material B.

[0131] After the mixing is completed, Material B is discharged, placed in a crucible, transferred into a kiln, and sintered by introducing oxygen (≥95%). The temperature is raised and lowered according to a set program. Finally, the temperature in the constant temperature section is set to 725°C. After the constant temperature sintering is completed, the oxygen supply is stopped and N2 is introduced instead. After cooling to room temperature, the material is taken out, pulverized, washed with water, and centrifugally dried to obtain the material C to be coated.

[0132] Take 10 g of the nano double-phase coupling initiator CeN (1500 ppm) and disperse and mix it with 30 g of deionized water in a ratio of 1:3 (mass ratio) to obtain the mixed solution D. The mixed solution D is sprayed into 5 kg of the material C to be coated at the same rate in the medium-speed stage. The subsequent mixing process is the same as the raw material mixing process.

[0133] After the mixing is completed, the material is transferred into a kiln. The temperature is raised and lowered according to a set program while introducing oxygen (≥90%) for sintering. The constant temperature is set to 680°C. After the heat preservation is completed, it is cooled to room temperature with the furnace to obtain the cathode material LiNi 0.92 Co 0.03 Mn 0.03 Al 0.02 B 0.25 Ce 0.15 N 0.35 O2.

[0134] Example 6

[0135] Disperse and mix 53 g of the nano double-phase coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water in a ratio of 1:3 (mass ratio) to obtain the mixed solution A. According to a ratio of 1.04:1.0 (molar ratio), 2.36 kg of lithium hydroxide and 5 kg of the nickel-rich precursor Ni 0.95 Co 0.02 Mn 0.02 Al 0.01 (OH)2 are added to a high-speed mixer for mixing. The mixed solution A is ultrasonically atomized and sprayed into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage is completed, it is transferred to the high-speed mixing stage, and microwave radiation drying is started simultaneously to obtain Material B.

[0136] After the mixing is completed, Material B is discharged, placed in a crucible, transferred into a kiln, and sintered by introducing oxygen (≥99%). The temperature is raised and lowered according to a set program. Finally, the temperature in the constant temperature section is set to 715°C. After the constant temperature sintering is completed, the oxygen supply is stopped and N2 is introduced instead. After cooling to room temperature, the material is taken out, pulverized, washed with water, and centrifugally dried to obtain the material C to be coated.

[0137] Take 10 g of the nano dual-phase coupling initiator CeN (1500 ppm) and disperse and mix it with 30 g of deionized water in a ratio of 1:3 (mass ratio) to obtain the mixed solution D. Spray the mixed solution D into 5 kg of the material C to be coated at the same rate in the medium-speed stage. The subsequent material mixing process is the same as the raw material mixing process.

[0138] After the mixing is completed, transfer the material to a kiln furnace. Set the program to raise and lower the temperature and simultaneously introduce oxygen (≥90%) for sintering. Set the constant temperature to 680 °C. After the heat preservation is completed, cool it to room temperature with the furnace to obtain the cathode material LiNi 0.95 Co 0.02 Mn 0.02 Al 0.01 B 0.25 Ce 0.15 N 0.35 O2.

[0139] Example 7

[0140] Add 2.35 kg of lithium hydroxide, 5 kg of nickel-rich precursor Ni 0.90 Co 0.06 Mn 0.04 (OH)2 and 53 g of the nano dual-phase coupling initiator N2H4BH3 (2500 ppm) into a high-speed mixer simultaneously and mix the materials according to the program.

[0141] After the mixing is completed, discharge the material, load it into a crucible, transfer it to a kiln furnace, introduce oxygen (≥95%) for sintering, set the program to raise and lower the temperature, and finally set the temperature in the constant temperature section to 750 °C. After the constant temperature sintering is completed, stop introducing oxygen and switch to introducing N2. After cooling to room temperature, take out the material, and obtain the material to be coated after crushing, washing with water, centrifuging and drying.

[0142] Take 10 g of the nano dual-phase coupling initiator CeN (1500 ppm) and 5 kg of the material to be coated and put them into a high-speed mixer, and mix the materials according to the program. After the mixing is completed, transfer the mixed material to a kiln furnace, set the program to raise and lower the temperature and simultaneously introduce oxygen (≥90%) for sintering. Set the constant temperature to 680 °C. After the heat preservation is completed, cool it to room temperature with the furnace to obtain the cathode material LiNi 0.90 Co 0.06 Mn 0.04 B 0. 25 Ce 0.15 N 0.35 O2.

[0143] Example 8

[0144] Disperse and mix 53 g of nano-biphasic coupling initiator N2H4BH3 (2500 ppm) with 159 g of deionized water in a 1:3 ratio (mass ratio) to obtain mixture A. Mix 2.35 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.90 Co 0.06 Mn 0.04 (OH)2 in a high-speed mixer. Ultrasonically atomize mixture A and spray it into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage ends, transfer to the high-speed mixing stage and simultaneously start microwave radiation drying to obtain material B.

[0145] After the mixing is completed, discharge material B, place it in a crucible, transfer it to a kiln, and introduce oxygen (≥95%) for sintering. Set the program for temperature rise and fall. The final constant temperature section is set at 750 °C. After the constant temperature sintering is completed, stop introducing oxygen and switch to introducing N2. After cooling to room temperature, take out the material, and obtain the material C to be coated after pulverization, washing, centrifugation, and drying.

[0146] Take 8 g of nano-biphasic coupling initiator W2N (1500 ppm) and disperse and mix it with 24 g of deionized water in a 1:3 ratio (mass ratio) to obtain mixture D. Spray mixture D into 5 kg of material C to be coated at the same rate in the medium-speed stage. The subsequent mixing process is the same as the raw material mixing process.

[0147] After mixing, transfer the material to a kiln, set the program for temperature rise and fall, and introduce oxygen (≥90%) for sintering. The constant temperature is set at 650 °C. After the heat preservation is completed, cool it to room temperature in the furnace to obtain the cathode material LiNi 0.90 Co 0.06 Mn 0.04 B 0.25 W 0.15 N 0.35 O2 modified by anion-cation biphasic coupling of Example 8.

[0148] Comparative Example 1

[0149] Disperse and mix 71 g of H3BO3 (2500 ppm) with 213 g of deionized water in a 1:3 ratio (mass ratio) to obtain mixture A. Mix 2.35 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.90 Co 0.06 Mn 0.04 (OH)2 in a high-speed mixer. Ultrasonically atomize mixture A and spray it into the mixed raw materials at a rate of 20 mL / min in the medium-speed mixing stage. After the medium-speed mixing stage ends, transfer to the high-speed mixing stage and simultaneously start microwave radiation drying to obtain material B.

[0150] After the mixing of materials is completed, Material B is discharged, placed in a sagger, transferred into a kiln, and sintered by introducing oxygen (≥95%). The temperature is raised and lowered according to a set program. Finally, the temperature in the constant temperature section is set to 750°C. After the constant temperature sintering is completed, the oxygen supply is stopped and N2 is introduced instead. After cooling to room temperature, the material is taken out, pulverized, washed with water, and dried by centrifugation to obtain the material C to be coated.

[0151] Take 10 g of the nano-biphasic coupling initiator CeN (1500 ppm) and 30 g of deionized water, disperse and mix them in a 1:3 ratio (mass ratio) to obtain the mixed solution D. The mixed solution D is sprayed into 5 kg of the material C to be coated at the same rate in the medium-speed stage. The subsequent material mixing process is the same as the raw material mixing process.

[0152] After the mixing is completed, the material is transferred into a kiln. The temperature is raised and lowered according to a set program while introducing oxygen (≥90%) for sintering. The constant temperature is set to 680°C. After the heat preservation is completed, it is cooled to room temperature in the furnace to obtain the doped and coated modified cathode material LiNi 0.90 Co 0.06 Mn 0.04 B 0. 25 Ce 0.15 O2.

[0153] Comparative Example 2

[0154] According to a ratio of 1.04:1.0 (molar ratio), 2.35 kg of lithium hydroxide and 5 kg of the nickel-rich precursor Ni 0.90 Co 0.06 Mn 0.04 (OH)2 are added to a high-speed mixer and mixed according to a program. After completion, the material is discharged, placed in a sagger, transferred into a kiln, and sintered by introducing oxygen (≥95%). The temperature is raised and lowered according to a set program. Finally, the temperature in the constant temperature section is set to 750°C. After the constant temperature sintering is completed, the oxygen supply is stopped and N2 is introduced instead. After cooling to room temperature, the material is taken out, pulverized, washed with water, and dried by centrifugation to obtain the material to be coated.

[0155] Take 10 g of the nano-biphasic coupling initiator CeN (1500 ppm) and 30 g of deionized water, disperse and mix them in a 1:3 ratio (mass ratio) to obtain a mixed solution. The mixed solution is sprayed into 5 kg of the material to be coated at a rate of 20 mL / min in the medium-speed stage. After the medium-speed mixing stage is completed, it is transferred to the high-speed mixing stage, and at the same time, microwave radiation drying is started.

[0156] After the mixing is completed, the material is discharged and transferred into a kiln. The temperature is raised and lowered according to a set program while introducing oxygen (≥90%) for sintering. The constant temperature is set to 680°C. After the heat preservation is completed, it is cooled to room temperature in the furnace to obtain the coated and modified cathode material LiNi 0.90 Co 0.06 Mn 0.04Ce 0.15 O2。

[0157] Comparative Example 3

[0158] 2.35 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.90 Co 0.06 Mn 0.04 (OH)2 were added to a high-speed mixer and mixed according to the procedure. After completion, the material was discharged and placed in a crucible, then transferred into a kiln and sintered by introducing oxygen (≥95%). The temperature was set to rise and fall according to the program, and the final constant temperature section was set at 750 °C. After the constant temperature sintering was completed, the oxygen supply was stopped and N2 was introduced instead. After cooling to room temperature, the material was taken out, crushed, washed with water, and centrifugally dried to obtain the unmodified LiNi 0.90 Co 0.06 Mn 0.04 O2。

[0159] Comparative Example 4

[0160] 53 g of nano-biphase coupling initiator N2H4BH3 (2500 ppm) and 159 g of deionized water were dispersed and mixed in a ratio of 1:3 (mass ratio) to obtain mixture A. 2.38 kg of lithium hydroxide and 5 kg of nickel-rich precursor Ni 0.92 Co 0.03 Mn 0.03 Al 0.02 (OH)2 were added to a high-speed mixer for mixing. Mixture A was ultrasonically atomized and sprayed into the mixed raw materials at a rate of 20 mL / min during the medium-speed mixing stage. After the medium-speed mixing stage ended, it was transferred to the high-speed mixing stage, and at the same time, microwave radiation drying was started to obtain material B.

[0161] After the mixing was completed, material B was discharged, placed in a crucible, then transferred into a kiln and sintered by introducing oxygen (≥95%). The temperature was set to rise and fall according to the program, and the final constant temperature section was set at 725 °C. After the constant temperature sintering was completed, the oxygen supply was stopped and N2 was introduced instead. After cooling to room temperature, the material was taken out, crushed, washed with water and dried to obtain the LiNi 0.90 Co 0.06 Mn 0.04 B 0.25 N 0.35 O2。

[0162] Figures 1 to 7 They are the scanning electron microscope images of the cathode materials of Examples 1 to 7 respectively. The nano-biphase coupling initiators used in each example are N2H4BH3 and CeN, Figure 8SEM image of the cathode material of Example 8, which is different from that of Example 4 in that the nano-biphasic coupling initiator used to construct the high-entropy phase surface is replaced by W2N. Through ultrasonic atomization and microwave radiation-assisted drying, the initiator is uniformly coated on the outer surface of the secondary particles. Due to the differences in the Ni content and morphology of the Ni-rich precursor, the primary particles of the finally produced Ni-rich cathode material are different, but the outer surface of the overall primary particles and the grain boundaries of the secondary spherical particles are covered by the coating layer, and the exposed area of the fresh phase interface is small, effectively reducing the contact area between the material and the electrolyte, and effectively reducing the dissolution of transition metal elements and the occurrence of side reactions at the two-phase interface during electrochemical tests.

[0163] In Example 7, on the basis of Example 4, the ultrasonic atomization and microwave-assisted method were replaced by the commonly used high-speed mixer dry mixing method. Figure 7 It can be seen from the electron microscope that the disadvantages of the traditional dry mixing method in terms of coating uniformity are very obvious. A blurred coating layer can be seen on the surface of the secondary particles, the coating effect on the outer surface of the primary particles is poor, and the grain boundary interface is obviously exposed, which is easily affected by side reactions and the dissolution of metal elements during electrochemical tests, resulting in a decrease in electrochemical performance. Figures 9 to 12 SEM images of the cathode materials of Comparative Examples 1 to 4 are shown respectively. In Comparative Example 1, on the basis of Example 4, only nano-boric acid was doped in the first sintering, and the coating still used the nano-initiator CeN and the atomization microwave-assisted method. The overall coating effect in the electron microscope is basically the same as that of Example 4, the coating layer is uniform, and it can be Figure 9 directly observed.

[0164] In Comparative Example 2, the doping of nano-boric acid was removed on the basis of Comparative Example 1, and only the atomization microwave-assisted coating of CeN was retained. Therefore, the overall electron microscope morphology is basically the same as that of Comparative Example 1 and Example 4, without obvious differences.

[0165] Figure 11 is a Ni-rich cathode material without any modification, and the surfaces and grain boundaries of its primary particles and secondary particles are clearly visible, and some of the primary particles show surface damage caused by processes such as crushing and water washing. Figure 12 is a Ni-rich cathode material that has only undergone low-entropy internal core construction with a nano-biphasic coupling initiator once. Since the high-entropy phase surface has not been constructed, the electron microscope is similar to Figure 11 and there are also some broken primary particles.

[0166] In order to prove the electrochemical performance of the materials, the cathode materials of the above Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to electrical performance tests of related coin cells, and the specific process is as follows:

[0167] (1) Take the cathode materials obtained in Examples 1 to 5 and Comparative Examples 1 to 4, and weigh three materials according to the ratio of 96 (cathode material): 2 (binder PVDF): 2 (conductive agent SP);

[0168] (2) Add the solvent NMP and disperse and mix evenly in a beaker to make a slurry, and then coat it on the conductive aluminum foil with a doctor blade (surface density 20.0 - 22.0 mg / cm 2 )

[0169] (3) Place it in a vacuum drying oven at 120°C and dry for 2 h, then cut it into a pole piece with a diameter of 14 mm, weigh it, and then perform vacuum baking at 120°C for 2 h;

[0170] (4) Use lithium metal as the negative electrode and assemble a CR2025 coin cell in a nitrogen glove box;

[0171] (5) Place the coin cell in a Neware test system at a constant temperature of 25°C for charge and discharge tests.

[0172] To prove the effect of the initiator on the crystal structure and electrochemical performance, Table 1 lists the initial charge capacity at 0.1C and the discharge capacities at the rate of 0.2C - 2C of Examples 1 - 8 and Comparative Examples 1 - 4, as well as the 003 / 104 peak intensity ratio θ of Examples 4, 7 and Comparative Examples 1 - 4. Figure 13 The first electrochemical charge - discharge curves of Examples 4, 7 and Comparative Examples 1 - 4 are listed.

[0173] Table 1 Battery performance results of each example and comparative example

[0174]

[0175] From Table 1 and Figure 13 the curves, it can be seen that under the same chemical formula, Example 4 that completed the biphasic coupling with two initiators and was modified by atomized microwave assistance has the best electrochemical performance compared with Comparative Examples 1 - 4. The discharge capacity at 0.1C reaches 222 mAh / g, and the discharge capacity at a rate of 2C can reach 188 mAh / g. Its crystal structure analysis shows that the intensity ratio of the 003 / 104 diffraction peak is 1.41. After replacing the biphasic coupling initiator that constructs the high - entropy phase surface on the basis of Example 4, the electrochemical performance of Example 8 is basically at the same level as that of Example 4, proving that this method has good practicability and applicability.

[0176] Secondly, in Example 7, only the initiator was used to complete the biphasic coupling modification. Its 0.1C discharge capacity was 219 mAh / g, and its 2C discharge capacity was 184 mAh / g. There was a slight loss in capacity compared to Example 4. The reason might be that the dry mixing was carried out using a high-speed mixer. During the in-phase mixing process, the contact area between the initiator and the nickel-rich cathode precursor was small. Affected by the rotation speed and material viscosity during the mixing process, the amount of initiator actually participating in the biphasic coupling reaction was less than the designed amount. The results of crystal structure analysis were not very different from those of Example 4. At a relatively high rate, after Li was removed, the unit cell volume shrank and the structure collapsed, resulting in a decrease in capacity.

[0177] In Comparative Example 1, based on Example 4, only cation modification was carried out in the first high-temperature sintering stage. Its 0.1C discharge capacity was only 217 mAh / g, and its 2C discharge capacity was 175 mAh / g, proving that single cation modification could not effectively complete atomic-level structural design and defect repair. Therefore, the 003 / 104 peak intensity ratio decreased to 1.35. The loss of reversible specific capacity and rate discharge capacity during the first charge and discharge was greater than that of the anion-cation coupling modification.

[0178] In Comparative Example 2, based on Example 4, only the construction process of the high-entropy phase on the surface of the initiator was completed. There were many atomic defects and oxygen vacancies inside the structure. The 003 / 104 peak intensity ratio was only 1.30, and the loss of reversible capacity was extremely large. The 0.1C initial discharge capacity was only 213 mAh / g, and the 2C discharge capacity decreased to 170 mAh / g.

[0179] In Comparative Example 3, the blank group was a nickel-rich material without any modification. The internal structure had serious Li / Ni mixing, many O vacancies, and chaotic atomic arrangement. The peak intensity ratio further decreased to 1.25, and the surface was severely damaged due to reasons such as water washing and pulverization. The 0.1C discharge capacity was only 205 mAh / g, and the 2C rate capacity only reached 161 mAh / g.

[0180] In Comparative Example 4, based on Example 4, only the construction process of the low-entropy phase core of the initiator was completed. The internal structure was stable. Crystal structure analysis showed that the 003 / 104 diffraction peak intensity ratio was similar to that of Example 4. However, the high-entropy phase was not constructed on the surface, and pulverization and water washing damaged the material surface. Therefore, the ionic and electronic conductivity was affected to a certain extent. The 0.1C discharge capacity was 214 mAh / g, and the 2C rate capacity was similar to that of Comparative Example 2, which was 169 mAh / g.

[0181] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application.

[0182] In addition, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, the combination of features of different embodiments means that it is within the scope of the present application and forms different embodiments. For example, in the claims above, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is only intended to deepen the understanding of the overall background art of the present application and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those skilled in the art.

Claims

1. A nickel-rich positive electrode material, characterized in that: The nickel-rich positive electrode material comprises a core and a coating layer covering the core, wherein the core is doped with N element and cationic element, and the coating layer comprises N element and cationic element; the general chemical formula of the nickel-rich positive electrode material is LiNi x Co y Mn z Al 1-x-y-z C c D d N n O2; wherein 0.80≤x≤0.95, 0≤y≤0.10, 0≤z≤0.10, C is the cationic element doped in the core, 0.10≤c≤0.30, D is the cationic element in the coating layer, 0.10≤d≤0.20, and n≤0.45; The cationic element doped in the core is B; The cationic element in the coating layer is W or Ce; The nickel-rich positive electrode material is a spherical secondary particle composed of stacked primary particles; The preparation method of the nickel-rich positive electrode material comprises: A nickel-rich positive electrode material precursor and a lithium source are first mixed, and a first two-phase coupled initiator after ultrasonic atomization is sprayed into the mixture during the first mixing process, and microwave drying is performed to obtain a first mixture; Performing a first sintering on the first mixture to obtain a material to be coated; The material to be coated is subjected to a second mixing, and during the second mixing process, a second dual-phase coupling initiator after ultrasonic atomization is sprayed into the material, and microwave drying is performed to obtain a second mixture; Performing a second sintering on the second mixture to obtain the nickel-rich positive electrode material; Wherein, the first two-phase coupling initiator is N2H4BH3, and the second two-phase coupling initiator is CeN or W2N.

2. The nickel-rich positive electrode material according to claim 1, characterized in that At least one of the following conditions is met: (1) The thickness of the coating layer is 1-3 nm; (2) The D50 of the nickel-rich positive electrode material is 9.0 μm to 13.5 μm; (3) The specific surface area of ​​the nickel-rich positive electrode material is 0.25~0.80m 2 / g; (4) The tap density of the nickel-rich positive electrode material is ≥ 2.2 g / cm 3 ; (5) The 003 / 104 diffraction peak intensity ratio in the XRD characteristic peak of the nickel-rich positive electrode material is ≥1.30; (6) The length of the primary particles is 300-500 nm; (7) The aspect ratio of the primary particles is between 1.5 and 3.

0.

3. A method for preparing a nickel-rich positive electrode material as claimed in claim 1 or 2, characterized in that: include: A nickel-rich positive electrode material precursor and a lithium source are first mixed, and a first two-phase coupled initiator after ultrasonic atomization is sprayed into the mixture during the first mixing process, and microwave drying is performed to obtain a first mixture; Performing a first sintering on the first mixture to obtain a material to be coated; The material to be coated is subjected to a second mixing, and during the second mixing process, a second dual-phase coupling initiator after ultrasonic atomization is sprayed into the material, and microwave drying is performed to obtain a second mixture; Performing a second sintering on the second mixture to obtain the nickel-rich positive electrode material; Wherein, the first two-phase coupling initiator is N2H4BH3, and the second two-phase coupling initiator is CeN or W2N.

4. The method for preparing a nickel-rich positive electrode material according to claim 3, characterized in that: The first mixing process and the second mixing process both include: a first stage, a second stage, and a third stage in which the mixing speed increases in sequence; and meet at least one of the following conditions: A. The speed of the first stage is 50-400r / min, and the time is 1-5min; B. The speed of the second stage is 100-600r / min, and the time is 2-10min; C. The rotation speed of the third stage is 400-1000r / min, and the time is 10-20min; D. the first two-phase coupled initiator after ultrasonic atomization and the second two-phase coupled initiator after ultrasonic atomization are both sprayed in the second stage; E. The injection rate of the first two-phase coupling initiator after ultrasonic atomization and the second two-phase coupling initiator after ultrasonic atomization is 10-50 mL / min; F. the microwave drying is carried out in the third stage; G. The power of the microwave drying is 8-15 kW and the temperature is 50-80°C.

5. The method for preparing a nickel-rich positive electrode material according to claim 3 or 4, characterized in that: At least one of the following conditions is met: A. Based on the mass of the nickel-rich positive electrode material precursor, the amount of the first dual-phase coupling initiator added is 1000-3000ppm; B. Based on the mass of the material to be coated, the amount of the second dual-phase coupling initiator added is 1000-2000ppm; C. The first two-phase coupled initiator and the second two-phase coupled initiator are both secondary particles composed of primary particles, the particle size of the primary particles is ≤30nm, and the particle size of the secondary particles is 1μm~3μm; D. The first sintering comprises: continuously introducing oxygen, heating from room temperature to 450°C at a heating rate of 5°C / min and keeping the temperature for 2 hours, then heating to 600°C at a heating rate of 1°C / min and keeping the temperature for 2 hours, then heating to 700-800°C at a heating rate of 2°C / min and keeping the temperature for 10-15 hours; E. The second sintering includes: heating from room temperature to 500-700°C at a heating rate of 2°C / min and keeping the temperature for 6-12h; F. The chemical formula of the nickel-rich positive electrode material precursor is: Ni x Co y Mn z Al 1-x-y-z (OH)2, where 0.80≤x≤0.95, 0≤y≤0.10, 0≤z≤0.10; G. The particle size D50 of the lithium source is 1 μm to 5 μm; H. The lithium source is selected from any one of LiOH, Li2CO3, CH3COOLi, and Li2C2O4.

6. A positive electrode sheet, characterized in that: The nickel-rich positive electrode material comprises the nickel-rich positive electrode material according to any one of claims 1 to 2.

7. A lithium ion battery, characterized in that: Including the positive electrode sheet as described in claim 6.

8. An electrical equipment, characterized in that: Comprising the lithium ion battery as claimed in claim 7.

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