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

Abstract

This invention provides a high-nickel cathode material, its preparation method, and its applications. The high-nickel cathode material of this invention can effectively control the overall Co content of secondary particles, thus avoiding a decrease in the specific capacity of lithium-ion batteries due to excessively high overall Co content, which would affect energy density. It can also effectively inhibit electrolyte penetration and diffusion, resist electrolyte erosion of the high-nickel cathode material's interior, and prevent the electrolyte from reacting with the active materials inside the high-nickel cathode material, thereby improving the structural stability of the high-nickel cathode material and ultimately enhancing the cycle performance of lithium-ion batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a high-nickel positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] The rapid development of the electric vehicle market has led to an increasing demand for batteries, and high-nickel positive electrode materials are widely used in lithium ion batteries due to their high energy density and low cost advantages. However, the high-nickel positive electrode material will be unstable in structure during the charging and discharging process due to the oxidation and reduction reaction of nickel elements, thereby affecting the cycle stability of the battery. In addition, a large amount of residual alkali is often generated during the preparation of the high-nickel positive electrode material, and the reaction of the residual alkali with the electrolyte will cause capacity attenuation and safety problems of the battery.

[0003] To solve the above problems, a water washing process is usually used to remove the residual alkali in the high-nickel positive electrode material, and doping and coating methods are used to improve the structural stability of the high-nickel positive electrode material and reduce its side reaction with the electrolyte. For example, Zr, Ti, Al, Y, Sr and other dopants are added to improve the structural stability of the high-nickel positive electrode material, and Al, B, Ce, P, F, Cl, Br and other coating agents are added to reduce the side reaction of the high-nickel positive electrode material with the electrolyte. This has solved the problem of the cycle stability of the high-nickel positive electrode material to some extent, but there are still some other problems. First, the water washing process can effectively remove the residual alkali, but will cause a decrease in the energy density of the battery due to the loss of part of the active material. Second, although doping and coating can improve the stability of the high-nickel positive electrode material to some extent, in actual use, due to the high surface reactivity of the high-nickel material, the penetration and diffusion of the electrolyte easily cause a large number of side reactions on the surface of the high-nickel positive electrode material, thereby causing the active material inside the positive electrode material to be unable to be fully utilized, and further affecting the cycle performance of the battery. SUMMARY

[0004] The application provides a high-nickel positive electrode material, which can improve the specific capacity of the lithium ion battery, thereby improving the energy density, and can also improve the structural stability of the high-nickel positive electrode material, thereby ultimately improving the cycle performance of the lithium ion battery.

[0005] The application provides a preparation method of the high-nickel positive electrode material, which is simple to operate, does not contain a water washing process, can effectively remove the residual alkali in the high-nickel positive electrode material to avoid a decrease in the energy density of the battery due to the loss of part of the active material, and can further improve the cycle performance of the high-nickel positive electrode material by improving the sintering and coating conditions, thereby improving the utilization rate of the active material inside the secondary particles while ensuring the structural stability of the high-nickel positive electrode material, and improving the cycle performance of the battery.

[0006] The application further provides a lithium ion battery comprising the high-nickel positive electrode material or the high-nickel positive electrode material prepared by the preparation method.

[0007] The application provides a high-nickel positive electrode material, wherein the high-nickel positive electrode material is secondary particles formed by agglomeration of primary particles, the ratio of the surface Co content to the central Co content of the primary particles on the surface of the secondary particles is M1, the ratio of the surface Co content to the central Co content of the primary particles from the surface of the secondary particles to 1 / 2 of the spherical core of the secondary particles is M2, the ratio of the surface Co content to the central Co content of the primary particles in the spherical core of the secondary particles is M3, M1>M2>M3, M1 is greater than or equal to 2, M2 is greater than or equal to 1.5, and M3 is greater than or equal to 1.1.

[0008] The high-nickel positive electrode material as described above, wherein the chemical formula of the high-nickel positive electrode material is Li y Ni a Co b Mn c O2,

[0009] 0.98≤y≤1.10, 0.6≤a≤0.98, 0≤b≤0.4, and 0≤c≤0.4.

[0010] The high-nickel positive electrode material as described above, wherein the chemical formula of the high-nickel positive electrode material is Li y Ni a Co b Mn c A1 d B1 e O2,

[0011] 0.98≤y≤1.10, 0.6≤a≤0.98, 0≤b≤0.4, 0≤c≤0.4, 1.001≤d≤0.1, and 0.001≤e≤0.1.

[0012] A1 is at least one of Zr, Ti, Al, Y, and Sr;

[0013] B1 is at least one of Al, B, Ce, P, F, Cl, and Br.

[0014] The high-nickel positive electrode material as described above, wherein the central Co content of the primary particles on the surface of the secondary particles is greater than the central Co content of the primary particles from the surface of the secondary particles to 1 / 2 of the spherical core of the secondary particles, which is greater than the central Co content of the primary particles in the spherical core of the secondary particles.

[0015] The high-nickel positive electrode material as described above, wherein the average grain size of the primary particles is 150-350 nm.

[0016] And / or, the particle size D50 of the secondary particles is 7.5-12.5 μm.

[0017] And / or, the average particle compression strength of the secondary particles is 50-200 MPa.

[0018] The high-nickel positive electrode material as described above, wherein the high-nickel positive electrode material is detected by X-ray photoelectron spectroscopy XPS and inductively coupled plasma emission spectroscopy ICP-OES to obtain Co XPS , Ni XPS , Co ICP and Ni ICP ; Co XPS , Ni XPS , Co ICP and Ni ICP satisfy the relational expression of formula 1:

[0019]

[0020] wherein Co XPS is the surface Co content of the secondary particles; Ni XPS is the surface Ni content of the secondary particles; Co ICP is the total Co content of the secondary particles; Ni ICP is the total Ni content of the secondary particles.

[0021] And / or, the high-nickel positive electrode material is detected by X-ray diffraction XRD to obtain the diffraction peak intensity I003 of the (003) plane and the diffraction peak intensity I104 of the (104) plane, and the ratio I003 / I104 is 1.8-3.0.

[0022] The application provides a preparation method of the high-nickel positive electrode material.

[0023] The precursor Ni a Co b Mn c (OH)2 and a lithium source are mixed to perform first sintering to obtain first sintered material, and the first sintered material is crushed to obtain first crushed material with a particle size D50 of 7.5-12.5 μm.

[0024] The first crushed material and a Co source are mixed to perform second sintering to obtain the high-nickel positive electrode material.

[0025] wherein 0.6≤a≤0.98, 0≤b≤0.4, and 0≤c≤0.4.

[0026] The second sintering temperature is 540-640 ℃, and the second sintering time satisfies the relational expression of formula 2:

[0027]

[0028] Wherein, t is the second sintering time, h; D is the average grain size of the first broken material primary particle, nm; D50 is the particle size D50 of the first broken material secondary particle, μm; T is the second sintering temperature, ℃.

[0029] The preparation method as described above, wherein the first sintering temperature is 750-900 ℃, and the first sintering time is 8-15 h.

[0030] The preparation method as described above, wherein before the first sintering, further comprising mixing the precursor Ni a Co b Mn c (OH)2, a lithium source and an A1 dopant;

[0031] The second sintering further comprises obtaining a second sintering material after the second sintering; mixing the second sintering material and a B1 coating agent to perform a third sintering, thereby obtaining the high-nickel positive electrode material;

[0032] The A1 dopant comprises at least one of a Zr source, a Ti source, an Al source, a Y source and a Sr source;

[0033] The B1 coating agent comprises at least one of an Al source, a B source, a Ce source, a P source, a F source, a Cl source and a Br source;

[0034] The third sintering temperature is 240-340 ℃, and the third sintering time is 4-15 h.

[0035] The application further provides a lithium ion battery comprising the high-nickel positive electrode material or the high-nickel positive electrode material prepared by the preparation method.

[0036] The application provides a high-nickel positive electrode material, when the position of a primary particle is closer to the center of a secondary particle, the ratio of the Co content on the surface of the primary particle to the Co content in the center of the primary particle is smaller, the high-nickel positive electrode material can effectively control the Co content of the whole secondary particle, so as to avoid the decrease of the gram capacity of the lithium ion battery caused by the too high Co content of the whole secondary particle, and further affect the energy density, can effectively inhibit the penetration and diffusion of the electrolyte, avoid the active substance in the high-nickel positive electrode material from being not fully utilized, and further improve the structural stability of the high-nickel positive electrode material, and finally improve the cycle performance of the lithium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is the whole TEM image of the high-nickel positive electrode material in Example 1.

[0038] Figure 2 It is the local TEM image of the surface of the secondary particle in the high-nickel positive electrode material in Example 1.

[0039] Figure 3This is an EDS surface distribution diagram of Zr element located on the surface of secondary particles in the high-nickel cathode material of Example 1;

[0040] Figure 4 This is an EDS surface distribution diagram of Al elements located on the surface of secondary particles in the high-nickel cathode material of Example 1;

[0041] Figure 5 This is an EDS surface distribution diagram of Co element located on the surface of secondary particles in the high-nickel cathode material of Example 1;

[0042] Figure 6 This is a partial TEM image of the center of the secondary particles in the high-nickel cathode material of Example 1;

[0043] Figure 7 This is an EDS surface distribution diagram of Zr element located at the center of secondary particles in the high-nickel cathode material of Example 1;

[0044] Figure 8 This is an EDS surface distribution diagram of Al element located at the center of the secondary particle in the high-nickel cathode material of Example 1;

[0045] Figure 9 This is an EDS surface distribution diagram of the Co element located at the center of the secondary particle in the high-nickel cathode material of Example 1. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0047] The first aspect of this invention provides a high-nickel cathode material, which is a secondary particle formed by the agglomeration of primary particles. The ratio of the surface Co content to the central Co content of the primary particles located on the surface of the secondary particles is M1; the ratio of the surface Co content to the central Co content of the primary particles located from the surface of the secondary particles to half the distance from the center of the secondary particles is M2; and the ratio of the surface Co content to the central Co content of the primary particles located at the center of the secondary particles is M3. M1 > M2 > M3; M1 ≥ 2, M2 ≥ 1.5, and M3 ≥ 1.1.

[0048] The high-nickel cathode material of the present invention is a secondary particle formed by the agglomeration of primary particles. The primary particles refer to individual fine grains. These grains generally have a large surface energy and are therefore prone to agglomeration due to weak interaction forces, thus forming secondary particles.

[0049] High-nickel cathode materials offer advantages such as high energy density and high capacity in lithium-ion batteries, but they also suffer from problems such as poor cycle stability and low safety. To improve these issues, surface coating treatment is typically applied to high-nickel cathode materials, with cobalt (Co) coating being a common method.

[0050] In this invention, M1, M2, and M3 of the high-nickel cathode material are defined to satisfy the above-mentioned relationship: the closer the primary particle is to the center of the secondary particle, the smaller the ratio of the Co content on the surface of the primary particle to the Co content at the center of the primary particle, and the ratio satisfies M1≥2, M2≥1.5, and M3≥1.1. This indicates that in the high-nickel cathode material of this invention, Co is more concentrated on the surface of the primary and secondary particles, and less distributed in the bulk phase. Therefore, compared with the cathode materials in the prior art where the Co concentration gradient decreases from the surface to the center of the secondary particle, this invention provides a significant advantage. In comparison, this invention can more effectively control the overall Co content of the secondary particles, so as to avoid the decrease in the specific capacity of the lithium-ion battery due to excessively high overall Co content of the secondary particles, which would affect the energy density. At the same time, through the above-mentioned relationship limitation, it can also effectively inhibit the penetration and diffusion of electrolyte, resist the erosion of the high-nickel cathode material by the electrolyte, and prevent the electrolyte from reacting with the active materials inside the high-nickel cathode material. This improves the stability of the high-nickel cathode material, increases the utilization rate of the active materials inside the high-nickel cathode material, and ultimately improves the specific capacity and cycle performance of the lithium-ion battery.

[0051] It is understandable that the values ​​of M1, M2, and M3 satisfying M1≥2, M2≥1.5, and M3≥1.1 refer to the following: for primary particles located on the surface of secondary particles, the surface Co content is 2 times or more than the central Co content; for primary particles located from the surface of secondary particles to 1 / 2 of the center of the secondary particle, the surface Co content is 1.5 times or more than the central Co content; and for primary particles located at the center of the secondary particle, the surface Co content is 1.1 times or more than the central Co content.

[0052] In one embodiment, the primary particles located on the surface of the secondary particles have a surface Co content of 8.1 wt% and a center Co content of 3.4 wt%, i.e., M1 is 2.4; the primary particles located from the surface of the secondary particles to halfway from the center of the secondary particles have a surface Co content of 5.9 wt% and a center Co content of 3.1 wt%, i.e., M2 is 1.9; and the primary particles located at the center of the secondary particles have a surface Co content of 3.7 wt% and a center Co content of 3.0 wt%, i.e., M3 is 1.2.

[0053] In one optional embodiment, the high-nickel cathode material has the chemical formula Li. y Ni a Co b Mn cO2, where 0.98≤y≤1.10, 0.6≤a≤0.98, 0≤b≤0.4, and 0≤c≤0.4.

[0054] By limiting the composition and ratio of high-nickel cathode materials, it is possible to further improve specific capacity and energy density, as well as structural stability, thereby enhancing cycle performance.

[0055] In another alternative embodiment, the high-nickel cathode material has the chemical formula Li. y Ni a Co b Mn c A1 d B1 e O2, where 0.98≤y≤1.10, 0.6≤a≤0.98, 0≤b≤0.4, 0≤c≤0.4, 0.001≤d≤0.1, 0.001≤e≤0.1;

[0056] A1 is at least one of Zr, Ti, Al, Y, and Sr;

[0057] B1 is at least one of Al, B, Ce, P, F, Cl, and Br.

[0058] In this invention, to further improve structural stability and cycle performance, the high-nickel cathode material may further include an Al dopant element and a B1 coating layer. Using an Al dopant element, and limiting the selection of the Al dopant element to the above-mentioned range, allows the Al dopant element to be incorporated into the bulk phase of the cathode material, thereby increasing the particle withstand voltage of secondary particles, reducing transition metal mixing and stabilizing the crystal structure, mitigating lattice contraction and expansion of the cathode material during charging and discharging, and improving structural stability. Using a B1 coating layer, and limiting the selection of the B1 coating layer to the above-mentioned range, provides protection to the surface of the cathode material, slowing down side reactions between the electrolyte and the cathode material surface, and further improving the cycle performance of the lithium-ion battery.

[0059] Therefore, by limiting the composition and ratio of high-nickel cathode materials to meet the above range, Al doping elements and B1 coating layers can be introduced to further improve structural stability and thus enhance cycle performance.

[0060] In one specific embodiment, the Co content at the center of the primary particle located on the surface of the secondary particle is greater than the Co content at the center of the primary particle located at 1 / 2 of the distance from the surface of the secondary particle to the center of the secondary particle, which is greater than the Co content at the center of the primary particle located at the center of the secondary particle.

[0061] The cathode material obtained by the present invention, as defined above, exhibits a lower Co content at the center of the primary particle as the primary particle is closer to the center of the secondary particle. This not only further controls the overall Co content of the secondary particle to avoid excessively high Co content leading to a decrease in the specific capacity of the lithium-ion battery and thus affecting the energy density, but also further inhibits electrolyte penetration and diffusion, resists electrolyte erosion of the high-nickel cathode material, and prevents the electrolyte from reacting with the active materials inside the high-nickel cathode material. This improves the structural stability of the high-nickel cathode material, increases the utilization rate of the active materials inside the high-nickel cathode material, and ultimately improves the specific capacity and cycle performance of the lithium-ion battery.

[0062] In the embodiment of the present invention, the average grain size of the primary particles is 150-350 nm;

[0063] And / or, the particle size D50 of the secondary particles is 7.5-12.5 μm;

[0064] And / or, the average compressive strength of the secondary particles is 50-200 MPa.

[0065] In high-nickel cathode materials, an excessively large average grain size of primary particles leads to slow lithium-ion transport speed, affecting cycle performance; an excessively small average grain size of primary particles leads to insufficient sintering, low specific capacity, low particle compressive strength, and a large BET specific surface area, all of which affect cycle performance. Therefore, this invention limits the average grain size of primary particles to meet the above-mentioned range, which can effectively balance the energy density and cycle performance of high-nickel cathode materials.

[0066] In high-nickel cathode materials, if the particle size D50 of the secondary particles is too large, the lithium ions inside the material will not be fully extracted, affecting the specific capacity. If the particle size of the secondary particles is too small, the BET specific surface area will be too large, affecting the cycle performance. Therefore, the present invention limits the particle size D50 of the secondary particles to meet the above range, which can balance the energy density and cycle performance of high-nickel cathode materials.

[0067] Furthermore, limiting the average particle pressure resistance of secondary particles to meet the above range helps to further improve the structural stability of high-nickel cathode materials, thereby improving cycle performance.

[0068] In the present invention, the high-nickel cathode material is analyzed by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) to obtain Co. XPS Ni XPS Co ICP and Ni ICP Co XPS Ni XPS Co ICP and Ni ICPThe relation that satisfies equation 1 is:

[0069]

[0070] Among them, Co XPS The content of Co on the surface of secondary particles; Ni XPS Ni content on the surface of secondary particles; Co ICP The total Co content of secondary particles; Ni ICP The total Ni content of the secondary particles;

[0071] And / or, the diffraction peak intensities I003 of the (003) plane and I104 of the (104) plane obtained by X-ray diffraction (XRD) of high nickel cathode material satisfy I003 / I104 as 1.8-3.0.

[0072] X-ray photoelectron spectroscopy (XPS) is a technique that uses an electron spectrometer to measure the energy distribution of photoelectrons and Auger electrons emitted from the surface of a sample when irradiated with X-ray photons. It can be used for qualitative and semi-quantitative analysis, obtaining information such as the elemental composition, chemical state, and molecular structure of the sample surface from the peak position and shape of the XPS spectrum, and determining the elemental content or concentration from the peak intensity. Therefore, the high-nickel cathode material of this invention can yield Co by XPS detection. XPS The value represents the Co content on the surface of secondary particles, expressed in wt%. Similarly, Ni can also be obtained through XPS analysis. XPS , representing the Ni content on the surface of secondary particles, in wt%.

[0073] Inductively coupled plasma optical emission spectrometry (ICP-OES) is a technique that uses a light source that generates plasma discharge through high-frequency inductive coupling to perform atomic emission spectroscopic analysis. It is a flame technique with a flame temperature range of 6000 to 10000 K, and the emission intensity represents the concentration of elements in the sample. Therefore, the high-nickel cathode material of this invention can yield Co by ICP-OES analysis. ICP This represents the total Co content of secondary particles, expressed in wt%. Similarly, Ni can also be obtained by ICP-OES analysis. ICP , representing the total Ni content of secondary particles, in wt%.

[0074] When the Co of the high-nickel cathode material of the present invention XPS Ni XPS Co ICP and Ni ICPWhen the relationship in Equation 1 is satisfied, it indicates that the content of Co and Ni in the high-nickel cathode material has a good matching effect, and the Co coating effect on the surface of the secondary particles is good. Therefore, it can effectively suppress electrolyte penetration and diffusion, thereby improving the interface stability of the high-nickel cathode material and improving the cycle performance of lithium-ion batteries.

[0075] Furthermore, the Miller index is an index used to determine the orientation of a crystal, also known as the crystal plane index. This invention can obtain the diffraction peak intensities I003 on the (003) plane and I104 on the (104) plane of the high-nickel cathode material using X-ray diffraction (XRD). I003 / I104 can reflect the relative intensities of Li... + / Ni 2+ The degree of cation mixing, limiting the value to meet the above range, helps to further reduce transition metal mixing and thus improve cycle performance.

[0076] A second aspect of the present invention provides a method for preparing the above-mentioned high-nickel cathode material, comprising the following steps:

[0077] Ni precursor a Co b Mn c (OH)2 and lithium source are mixed and sintered to obtain a first sintered material. The first sintered material is crushed to obtain a first crushed material with a particle size D50 of 7.5-12.5μm.

[0078] The first crushed material and the Co source are mixed and then sintered to obtain a high-nickel cathode material.

[0079] Where 0.6≤a≤0.98, 0≤b≤0.4, 0≤c≤0.4;

[0080] The second sintering temperature is 540-640℃, and the second sintering time satisfies the relationship in Equation 2:

[0081]

[0082] Where t is the second sintering time, h; D is the average grain size of the primary particles of the first crushed material, nm; D50 is the particle size D50 of the secondary particles of the first crushed material, μm; and T is the second sintering temperature, ℃.

[0083] The preparation method of this invention is simple to operate and does not involve water washing. The introduction of a Co source effectively removes residual alkali from the high-nickel cathode material, preventing the loss of some active material and thus reducing the battery's energy density. By improving sintering conditions, a high-nickel cathode material with a specific Co concentration gradient is obtained, further improving the cycle performance of the high-nickel cathode material. While ensuring the structural stability of the high-nickel cathode material, the utilization rate of active material within the secondary particles is increased, thereby enhancing the battery's cycle performance. First, the precursor Ni... a Co b Mn c The first sintered material is obtained by mixing (OH)2 with a lithium source and performing a first sintering. The first sintered material is then crushed and the D50 range is controlled to obtain a first crushed material. Subsequently, the first crushed material is mixed with a Co source and subjected to a second sintering to obtain a high-nickel cathode material. The above steps help to control the overall Co content of the secondary particles to improve the specific capacity and energy density of the lithium-ion battery, and suppress the penetration and diffusion of the electrolyte to improve the structural stability of the high-nickel cathode material and thus improve the cycle performance of the lithium-ion battery.

[0084] In this invention, the lithium source can be at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, lithium acetate, lithium oxide, and lithium citrate.

[0085] To more precisely control high-nickel cathode materials and improve their energy density and cycle performance, the precursor Ni can be... a Co b Mn c (OH)₂ and a lithium source are mixed at a molar ratio of 1:(1.010-1.090). Simultaneously, to ensure more thorough mixing, the precursor Ni can be added. a Co b Mn c (OH)2 and lithium source are added to a high-speed mixer for mixing. The mixing speed can be 500 rpm and the mixing time can be 60 min.

[0086] After the precursor and lithium source are thoroughly mixed, the first sintering is carried out. The precursor will undergo a solid-state lithium intercalation reaction during the first sintering to obtain the first sintered material. The first sintering has a key impact on the crystal structure of the high-nickel cathode material.

[0087] The atmosphere for the first sintering can be oxygen or air. To further improve sintering efficiency, a mixture of oxygen concentration ≥80% and the remaining gas is air can be selected.

[0088] After the first sintering is completed, the first sintered material is obtained. In order to facilitate subsequent operations and strengthen the control of the parameters of high-nickel cathode material, the first sintered material needs to be crushed and the D50 needs to be controlled within 7.5-12.5μm to obtain the first crushed material. The first crushed material is then used for subsequent experiments.

[0089] Next, to further precisely control the high-nickel cathode material to improve its energy density and cycle performance, the first crushed material and the Co source can be mixed at a molar ratio of 1:(0.001-0.100). The cobalt source can be at least one of cobalt tetroxide, cobalt carbonate, cobalt hydroxide, cobalt hydroxyl oxide, cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride. Simultaneously, to ensure more thorough mixing, the first crushed material and the Co source can be added to a high-speed mixer for mixing at a speed of 500 rpm for 60 minutes.

[0090] After the first crushed material and the Co source are thoroughly mixed, a second sintering is required within a limited temperature and time range. At this time, the Co source will react with the first crushed material and penetrate into the material, thereby obtaining the high nickel cathode material with a specific Co concentration gradient of the present invention.

[0091] During their long-term research, the inventors discovered that the temperature and time of the second sintering have a crucial impact on whether the high-nickel cathode material provided in the first aspect of this invention can be obtained. This invention first limits the second sintering temperature to 540-640℃. If the second sintering temperature is too low, Co mainly coats the surface of the secondary particles; if the second sintering temperature is too high, Co tends to be uniformly distributed in the bulk phase of the high-nickel cathode material. Only when the second sintering temperature meets the above limitations can a good foundation be laid for the specific gradient distribution of Co. After defining the second sintering temperature, the present invention defines the second sintering time to satisfy the relationship of Equation 2. That is, the second sintering time is adjusted according to the second sintering temperature, the average grain size of the primary particles of the first crushed material, and the particle size D50 of the secondary particles of the first crushed material. This can promote a good match between the second sintering time and the second sintering temperature, the average grain size of the primary particles of the first crushed material, and the particle size D50 of the secondary particles of the first crushed material, and finally obtain the high-nickel cathode material provided by the first aspect of the present invention. In the high-nickel cathode material, the closer the position of the primary particle is to the center of the secondary particle, the smaller the ratio of the Co content on the surface of the primary particle to the Co content at the center of the primary particle.

[0092] It is understood that the high-nickel cathode material obtained by mixing the first crushed material and the Co source and performing a second sintering in this invention has an average grain size of primary particles and a particle size D50 of secondary particles that are basically equivalent to the average grain size of the first crushed material and the particle size D50 of secondary particles.

[0093] In addition, the atmosphere for the second sintering can be oxygen or air. To further improve the sintering efficiency, a mixture of oxygen concentration ≥80% and the remaining gas is air can be selected.

[0094] In the present invention, the first sintering temperature is 750-900℃, and the first sintering time is 8-15h. As mentioned above, the first sintering has a key influence on the crystal structure of the high-nickel cathode material. Therefore, controlling the first sintering temperature and the first sintering time within the above range can obtain a suitable crystal structure, which in turn helps to improve the cycle performance of the battery to a certain extent and significantly increase the specific capacity.

[0095] In one specific embodiment, the process further includes preparing the precursor Ni before the first sintering. a Co b Mn c (OH)2, a mixture of lithium source and Al dopant;

[0096] The second sintering process also includes obtaining a second sintering material after the second sintering; mixing the second sintering material with B1 coating agent and performing a third sintering to obtain a high-nickel cathode material;

[0097] A1 dopants include at least one of Zr source, Ti source, Al source, Y source, and Sr source;

[0098] The B1 coating agent includes at least one of the following: Al source, B source, Ce source, P source, F source, Cl source, and Br source;

[0099] The third sintering temperature is 240-340℃, and the third sintering time is 4-15h.

[0100] In this invention, the precursor Ni can also be added before the first sintering. a Co b Mn c (OH)2, a lithium source, and an Al dopant are mixed, and then, after a second sintering, a second sintered material is mixed with a B1 coating agent and subjected to a third sintering to finally obtain a high-nickel cathode material. This invention, by limiting the types of Al dopant and B1 coating agent, as well as the temperature and time of the third sintering, can effectively improve the structural stability of the high-nickel cathode material and the cycle performance of lithium-ion batteries.

[0101] First, the precursor Ni a Co b Mn c (OH)₂, lithium source, and Al dopant are mixed and then subjected to the first sintering. During this process, the Al dopant is incorporated into the bulk phase of the cathode material, thereby improving the withstand voltage of the secondary particles, reducing transition metal mixing, stabilizing the crystal structure, and mitigating lattice contraction and expansion of the cathode material during charging and discharging. The Al dopant, including Zr, Ti, Al, Y, and Sr sources, can be at least one of oxides, hydroxides, hydroxyoxides, acetates, oxalates, nitrates, sulfates, and chlorides. Furthermore, the precursor Ni... a Co b Mnc (OH)2, lithium source and Al dopant can be mixed in a molar ratio of 1:(0.980-1.100):(0.001-0.100), which helps to better control the performance of high nickel cathode materials.

[0102] Secondly, after obtaining the second sintered material through the second sintering, the second sintered material and the B1 coating agent are mixed for a third sintering. By limiting the type of B1 coating agent and the temperature and time of the third sintering, the B1 coating agent can play a protective role on the surface of the cathode material, slowing down the side reactions between the electrolyte and the cathode material surface, and further improving the cycle performance of the lithium-ion battery. In the B1 coating agent, the Al source, B source, Ce source, P source, F source, Cl source, and Br source can be at least one of their oxides, hydroxides, hydroxyoxides, acetates, oxalates, nitrates, sulfates, and chlorides. Furthermore, mixing the second sintered material and the B1 coating agent at a molar ratio of 1:(0.001-0.100) helps to better control the performance of the high-nickel cathode material.

[0103] A third aspect of the present invention provides a lithium-ion battery comprising the high-nickel cathode material described above or the high-nickel cathode material prepared by the above preparation method.

[0104] The lithium-ion battery of the present invention includes a positive electrode sheet, which can be prepared by conventional techniques in the art. Specifically, the above-mentioned positive electrode material, conductive agent and binder can be uniformly dispersed in a solvent to obtain a positive electrode active layer slurry. Then, the positive electrode active layer slurry is coated on at least one functional surface of the positive electrode current collector and dried to obtain the positive electrode sheet.

[0105] The lithium-ion battery of the present invention includes, in addition to the positive electrode, a separator, a negative electrode, and an electrolyte. The composition of the negative electrode can refer to conventional negative electrode sheets in the art, and the separator can also be a conventionally used separator in the art. The lithium-ion battery of the present invention can be prepared using conventional methods in the art. Specifically, the positive electrode, separator, and negative electrode can be sequentially stacked, and a cell can be obtained through a stacking or winding process. Then, the lithium-ion battery is obtained through baking, electrolyte injection, formation, and packaging processes.

[0106] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, materials and instruments, all of which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthetic methods.

[0107] Example 1:

[0108] This embodiment provides a method for preparing a high-nickel cathode material, including the following steps:

[0109] (1) Ni precursor 0.85 Co 0.05 Mn 0.10 (OH)2, lithium source LiOH·H2O, Al dopant ZrO2, and Al2O3 were mixed in a molar ratio of 1:1.050:0.020:0.010 and added to a high-speed mixer for mixing at 500 rpm for 60 min. The mixed material was then placed in a sagger and subjected to a first sintering in a kiln at 820℃ for 12 h in an oxygen atmosphere (oxygen concentration ≥80%, the remainder being air) to obtain the first sintered material. The first sintered material was then crushed, with the D50 controlled at 9.5-10.5 μm to obtain the first crushed material.

[0110] (2) The first crushed material and the Co coating agent Co(OH)2 were mixed at a molar ratio of 1:0.015 and added to a high-speed mixer for mixing at a speed of 500 rpm for 60 min. The mixed material was then loaded into a sagger and subjected to a second sintering in a kiln at a temperature of 590℃ for a time of t. The second sintering atmosphere was oxygen (oxygen concentration ≥80%, with the remainder being air) to obtain the second sintered material.

[0111] The values ​​of t are shown in Equation 1:

[0112]

[0113] Where t is the second sintering time, h; D is the average grain size of the primary particles of the first crushed material, nm; D50 is the particle size D50 of the secondary particles of the first crushed material, μm; and T is the second sintering temperature, ℃.

[0114] (3) The second sintering material, B1 coating agent A1F3 and H3BO3 are mixed in a molar ratio of 1:0.010:0.010 and added to a high-speed mixer for mixing at a speed of 500 rpm for 60 min. The mixed material is then loaded into a sagger and subjected to a third sintering in a kiln at a temperature of 290℃ for 6 h. The third sintering atmosphere is oxygen (oxygen concentration ≥80%, the remainder is air) to obtain the third sintering material. After sieving, iron removal and packaging, the high-nickel cathode material is obtained.

[0115] Example 2:

[0116] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (1) of this embodiment, the Al dopant is TiO2 and Y2O3.

[0117] Example 3:

[0118] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1, the only difference being that in step (1) of this embodiment, the precursor Ni is... 0.85 Co 0.05 Mn 0.10 (OH)2 and lithium source LiOH·H2O were mixed at a molar ratio of 1:1.050, i.e. no Al dopant was added.

[0119] Example 4:

[0120] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (1) of this embodiment, the first sintering material is crushed and the D50 is controlled at 7.5-8.5μm.

[0121] Example 5:

[0122] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (1) of this embodiment, the first sintering material is crushed and the D50 is controlled at 11.5-12.5μm.

[0123] Example 6:

[0124] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (2) of this embodiment, the second sintering temperature is 540°C and the second sintering atmosphere is air.

[0125] Example 7:

[0126] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (2) of this embodiment, the second sintering temperature is 640°C and the second sintering atmosphere is oxygen (oxygen concentration ≥90%, the rest is air).

[0127] Example 8:

[0128] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (2) of this embodiment, the second sintering temperature is 590°C and the second sintering atmosphere is air.

[0129] Example 9:

[0130] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (3) of this embodiment, the B1 coating agent is CeF3 and NH4H2PO4.

[0131] Example 10:

[0132] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1, with the only difference being steps (2) and (3). In step (2) of this embodiment, the first crushed material and the Co coating agent Co(OH)2 are mixed at a molar ratio of 1:0.020. In step (3) of this embodiment, the second sintered material is directly sieved, iron removed, and packaged to obtain the high-nickel cathode material, i.e., without adding B1 coating agent.

[0133] Example 11:

[0134] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (3) of this embodiment, the third sintering time is 20h.

[0135] Example 12:

[0136] This embodiment provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Embodiment 1. The only difference is that in step (1) of this embodiment, the first sintering temperature is 740°C.

[0137] Comparative Example 1:

[0138] This comparative example provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Example 1. The only difference is that this comparative example does not perform step (2), but directly mixes the first crushed material with B1 coating agent A1F3 and H3BO3 in a molar ratio of 1:0.015:0.015.

[0139] Comparative Example 2:

[0140] This comparative example provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Example 1. The only difference is that in step (2) of this comparative example, the second sintering temperature is 520°C and the second sintering atmosphere is oxygen (oxygen concentration ≥90%, the rest is air).

[0141] Comparative Example 3:

[0142] This comparative example provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Example 1. The only difference is that in step (2) of this comparative example, the second sintering temperature is 660°C and the second sintering atmosphere is air.

[0143] Comparative Example 4:

[0144] This comparative example provides a method for preparing a high-nickel cathode material. The specific steps can be referred to in Example 1. The only difference is that in step (2) of this comparative example, the second sintering time is t+1h, that is, the second sintering time is always 1 hour longer than the sintering time in step (2) of Example 1.

[0145] Experimental example:

[0146] (1) X-ray diffraction (XRD) tests were performed using Bruker Corporation, specifically using Kα rays of Cu for powder X-ray diffraction to determine the average grain size of the primary particles of the first crushed material in the above examples and comparative examples. A Malvern laser particle size analyzer was used to determine the particle size D50 of the secondary particles of the first crushed material in the above examples and comparative examples. A Shimadzu micro-compression testing machine was used to determine the average particle compressive strength of the secondary particles of the high-nickel cathode material in the above examples and comparative examples. At least 10 particles with a D50 of diameter were tested for each sample, and the average value was taken. An X-ray photoelectron spectroscopy (XPS) instrument from Shimadzu Corporation was used to determine the weight percentage of surface Co in the high-nickel cathode material in the above examples and comparative examples to obtain the Co content. XPS The Ni content was obtained by measuring the weight percentage of Ni on the surface of the high-nickel cathode material. XPS The quantitative calculation employed the Wagner experimental sensitivity factor; the overall Co content of the high-nickel cathode materials in the above examples and comparative examples was determined using inductively coupled plasma optical emission spectrometry (ICP-OES) to obtain the Co content. ICP And the total Ni content to obtain Ni ICP XRD analysis was performed using Bruker's XRD method, specifically using Kα radiation from Cu for powder X-ray diffraction. The diffraction peak intensities I003 in the (003) plane and I104 in the (104) plane of the high-nickel cathode materials in the above examples and comparative examples were measured. Specific results are shown in Table 1. (The table likely shows the results based on Co...) XPS Ni XPS Co ICP and Ni ICP The M value can be obtained, and it is calculated using the following formula:

[0147]

[0148] (2) For the high-nickel cathode material with a particle size D50 of 7.5-12.5 μm for the secondary particles of the first crushed material in the above embodiments and comparative examples, focused ion beam (FIB) was used to prepare slices with a thickness of 50-100 nm. Subsequently, transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDS) was performed on the slices to obtain the elemental content of the primary particle surface and center. The specific results are shown in Table 2 and... Figures 1-9 As shown.

[0149] (3) The high-nickel positive electrode material from the above examples and comparative examples was mixed with conductive carbon black (Super-P) as a conductive agent and polyvinylidene fluoride (PVDF) as a binder at a mass ratio of 94.5:3:2.5, and an appropriate amount of N-methylpyrrolidone (NMP) solution was added to form a slurry. The slurry was then coated onto a positive electrode sheet made of aluminum foil, dried, and baked in a vacuum oven at 120°C for 12 hours. After the baking, the positive electrode sheet was assembled with an artificial graphite negative electrode sheet, a PP / PE / PP composite separator, and a 1.0M LiPF6 / ethylene carbonate (EC) + dimethyl carbonate (DMC) + ethyl methyl carbonate (EMC) electrolyte to obtain an 800mAh soft-pack battery, wherein the volume ratio of EC:DMC:EMC was 1:1:1. The specific capacity and 300-cycle retention rate of the above-mentioned soft-pack batteries were tested. The 300-cycle test conditions were 25℃, 2.8-4.25V, 1C. The specific results are shown in Table 2.

[0150] Table 1

[0151]

[0152]

[0153] Table 2

[0154]

[0155] As shown in Tables 1 and 2, in Example 2, the Al dopant used was replaced with TiO2 and Y2O3 compared to Example 1. It can be seen that this had no significant impact on the battery's specific capacity and cycle performance. In Example 3, no Al dopant was added compared to Example 1. It can be seen that the average particle breakdown strength and I003 / I104 of the secondary particles were extremely low, and its 300-cycle retention rate was worse than that of Examples 1 and 2, indicating that Al dopant can improve cycle performance. In Example 1, the D50 of the first crushed material was 9.5-10.5 μm, and in Example 4, the D50 of the first crushed material was... In Example 5, the D50 of the first crushed material was 7.5-8.5 μm, and in Example 6, the D50 of the first crushed material was 11.5-12.5 μm. It can be found that when the D50 of the first crushed material is 7.5-12.5 μm, the resulting battery has better specific capacity and cycle performance. In Example 1, the first sintering temperature was 590℃ and the second sintering atmosphere was mainly oxygen. In Example 7, the second sintering temperature was 540℃ and the second sintering atmosphere was air. In Example 8, the second sintering temperature was 640℃ and the second sintering atmosphere was mainly oxygen. Using air as the sintering agent, it was found that batteries with good specific capacity and cycle performance were obtained when the second sintering temperature was in the range of 540-640℃. In Example 9, the B1 coating agent was replaced with CeF3 and NH4H2PO4, and it was found that this had no significant impact on the specific capacity and cycle performance. In Example 10, no B1 coating agent was added, and it was found that the average particle pressure resistance of the secondary particles was lower, the M value was higher, and the specific capacity decreased. The retention rate after 300 cycles was significantly worse than in Examples 1 and 9, indicating that the B1 coating agent can significantly improve the specific capacity and cycle performance. Improving cycle performance also has a certain promoting effect on increasing specific capacity. The third sintering time of Example 11 was 20h, and its 300-cycle retention rate was significantly worse than that of Examples 1 and 9, indicating that when the third sintering time exceeds 15h, it will reduce the cycle performance of the obtained battery. The first sintering temperature of Example 12 was 740℃, and its average particle pressure resistance and I003 / I104 of the secondary particles were extremely low, and its specific capacity decreased significantly. The 300-cycle retention rate also decreased to a certain extent, indicating that if the first sintering temperature is too high, it will easily lead to a significant reduction in the specific capacity of the battery.

[0156] In Comparative Example 1, without step (2), the resulting high-nickel cathode material exhibited a low Co content on the surface of the primary particles located on the secondary particle surface, while the Co content at other locations remained relatively uniform. Its M value decreased significantly, and the 300-cycle retention rate decreased markedly. This indicates that step (2), i.e., the second sintering, plays a crucial role in obtaining the high-nickel cathode material of this invention, which possesses a specific Co concentration gradient and achieves a balance between specific capacity and cycle performance. In Comparative Example 2, the second sintering temperature was 520℃, and the second sintering atmosphere was primarily oxygen. It was observed that M2 in Comparative Example 2 was approximately 1.3, while M3 was approximately 1.0, indicating that more Co accumulated on the surface of the secondary particles, hindering the formation of a Co concentration gradient and failing to effectively improve cycle performance. In Comparative Example 3, the second sintering temperature was 660℃, and the second sintering atmosphere was air. It was observed that the M value in Comparative Example 3 decreased significantly, and Co was more uniformly distributed in the secondary particle bulk phase, hindering the formation of a Co concentration gradient and failing to effectively improve cycle performance. The second sintering time of Comparative Example 4 is 1 hour longer than that of Example 1, which means that the value relationship of Equation 1 is not satisfied. It can be found that M1 of Comparative Example 4 is about 1.8 and M2 is about 1.4, indicating that the distribution of Co tends to be uniform, which is not conducive to the formation of a special Co-rich structure on the surface of the primary particles. Its 300-cycle retention rate is significantly reduced, which shows that controlling the second sintering time plays an important role in improving cycle performance.

[0157] Figure 1 The TEM image of the high-nickel cathode material in Example 1 shows that the high-nickel cathode material of the present invention is a secondary particle formed by primary particle agglomeration.

[0158] Figure 2 This is a partial TEM image of the surface of secondary particles in the high-nickel cathode material of Example 1. Figure 3 This is an EDS surface distribution diagram of Zr element located on the surface of secondary particles in the high-nickel cathode material of Example 1. Figure 4 This is an EDS surface distribution diagram of Al elements located on the surface of secondary particles in the high-nickel cathode material of Example 1. Figure 5 This is an EDS surface distribution diagram of Co element located on the surface of secondary particles in the high-nickel cathode material of Example 1. According to... Figures 1-5 It can be observed that Zr and Al elements are relatively uniformly distributed on the surface of secondary particles, indicating that the Al dopant is uniformly doped; while the primary particles located on the surface of secondary particles have a significant concentration gradient of Co elements on the surface and at the center, with more Co elements uniformly coated on the surface of the primary particles.

[0159] Figure 6 This is a partial TEM image of the center of the secondary particles in the high-nickel cathode material of Example 1. Figure 7 This is an EDS surface distribution diagram of Zr element located at the center of the secondary particles in the high-nickel cathode material of Example 1. Figure 8This is an EDS surface distribution diagram of Al element located at the center of the secondary particle in the high-nickel cathode material of Example 1. Figure 9 This is an EDS surface distribution diagram of Co element located at the center of the secondary particles in the high-nickel cathode material of Example 1. According to... Figures 6-9 It can be observed that Zr and Al elements are still relatively evenly distributed at the center of the secondary particles, indicating that the Al dopant is still evenly doped at the center. However, the primary particles located at the center of the secondary particles have a more obvious concentration gradient of Co elements on their surface and at the center, with more Co elements evenly coated on the surface of the primary particles.

[0160] In addition, comparison Figure 5 and Figure 9 It can be observed that the surface Co element of the primary particles located on the surface of the secondary particles is significantly higher than that of the primary particles located at the center of the secondary particles. At the same time, the central Co element of the primary particles located on the surface of the secondary particles is significantly higher than that of the primary particles located at the center of the secondary particles.

[0161] The preferred embodiments and experimental verifications of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the protection scope of the present invention.

Claims

1. A high-nickel cathode material, characterized in that, The high-nickel cathode material is formed from secondary particles agglomerated from primary particles. The ratio of surface Co content to central Co content in the primary particles located on the surface of the secondary particles is M1; the ratio of surface Co content to central Co content in the primary particles located from the surface to halfway between the surface and the center of the secondary particles is M2; and the ratio of surface Co content to central Co content in the primary particles located at the center of the secondary particles is M3. M1 > M2 > M3; M1 ≥ 2, M2 ≥ 1.5, and M3 ≥ 1.1; the central Co content of the primary particles located on the surface of the secondary particles is greater than the central Co content of the primary particles located from the surface to halfway between the surface and the center of the secondary particles; the unit for Co content is wt%. The chemical formula of the high-nickel cathode material is Li. y Ni a Co b Mn c A1 d B1 e O2, Wherein, 0.98≤y≤1.10, 0.6≤a≤0.98, 0<b≤0.4, 0≤c≤0.4, 0.001≤d≤0.1, 0.001≤e≤0.1; A1 is at least one of Zr, Ti, Al, Y, and Sr; B1 is at least one of Al, B, Ce, P, F, Cl, and Br.

2. The high-nickel cathode material according to claim 1, characterized in that, The average grain size of the primary particles is 150-350 nm; And / or, the particle size D50 of the secondary particles is 7.5-12.5 μm; And / or, the average compressive strength of the secondary particles is 50-200 MPa.

3. The high-nickel cathode material according to claim 1, characterized in that, The high-nickel cathode material was analyzed by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectrometry (ICP-OES) to obtain Co. XPS Ni XPS Co ICP and Ni ICP The Co XPS Ni XPS Co ICP and Ni ICP The relation that satisfies equation 1 is: Formula 1; Wherein, the Co XPS The Co content on the surface of secondary particles is expressed in wt%; the Ni... XPS The Ni content on the surface of secondary particles is expressed in wt%; the Co... ICP The total Co content of the secondary particles is expressed in wt%; the Ni... ICP The total Ni content of the secondary particles is expressed in wt%. And / or, the high-nickel cathode material is subjected to X-ray diffraction (XRD) to obtain the diffraction peak intensities I003 of the (003) plane and I104 of the (104) plane, which satisfy the ratio of I003 / I104 as 1.8-3.

0.

4. A method for preparing the high-nickel cathode material according to any one of claims 1-3, characterized in that, Includes the following steps: Ni precursor a Co b Mn c (OH)2 and lithium source are mixed and sintered to obtain a first sintered material. The first sintered material is crushed to obtain a first crushed material with a particle size D50 of 7.5-12.5 μm. The first crushed material and the Co source are mixed and sintered in a second sintering process to obtain the high-nickel cathode material. Where 0.6≤a≤0.98, 0<b≤0.4, 0≤c≤0.4; The second sintering temperature is 540-640℃, and the second sintering time satisfies the relationship in Equation 2: Formula 2 Where t is the second sintering time, h; D is the average grain size of the primary particles of the first crushed material, nm; D50 is the particle size D50 of the secondary particles of the first crushed material, μm; T is the second sintering temperature, ℃; and before the first sintering, the precursor Ni is further subjected to... a Co b Mn c (OH)2, a mixture of lithium source and Al dopant; The second sintering process further includes obtaining a second sintering material after a second sintering; mixing the second sintering material and B1 coating agent and performing a third sintering to obtain the high-nickel cathode material.

5. The preparation method according to claim 4, characterized in that, The first sintering temperature is 750-900℃, and the first sintering time is 8-15 h.

6. The preparation method according to claim 4 or 5, characterized in that, The A1 dopant includes at least one of Zr source, Ti source, Al source, Y source, and Sr source; The B1 coating agent includes at least one of Al source, B source, Ce source, P source, F source, Cl source, and Br source; The third sintering temperature is 240-340℃, and the third sintering time is 4-15 h.

7. A lithium-ion battery, characterized in that, The lithium-ion battery includes the high-nickel cathode material according to any one of claims 1-3 or the high-nickel cathode material prepared by the preparation method according to claims 4-6.

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