High-nickel positive electrode material, preparation method thereof and lithium ion battery

Abstract

The invention provides a high-nickel positive electrode material, a preparation method thereof and a lithium ion battery, and belongs to the technical field of lithium ion batteries. According to the high-nickel positive electrode material, on one hand, overall uniform doping of LizNixCoyA1-x-yO2 particles is achieved through low-radius and high-activity metal ions, surface doping of the LizNixCoyA1-x-yO2 particles is achieved through high-radius and low-activity metal ions, and on the other hand, gradient distribution of elements is achieved through enrichment of the coating elements of the fast ion conductor coating layer on the surfaces of the LizNixCoyA1-x-yO2 particles, so that the high-nickel positive electrode material is obtained. And the structural stability of the high-nickel positive electrode material can be effectively improved, so that the cycling stability and the rate capability of the battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a high-nickel cathode material, a preparation method thereof, and a lithium-ion battery. Background Art

[0002] As a green battery with excellent performance such as high energy density, high working voltage platform, and no memory effect at present, high-nickel lithium-ion batteries have received more and more extensive attention. The cathode material is an important part of high-nickel lithium-ion batteries. Preparing a cathode material with high safety performance, high specific capacity, and stable cycle performance has an important impact on the development and application of high-nickel lithium-ion batteries.

[0003] However, although the high-nickel cathode material has a relatively high specific capacity, due to the lack of elements such as Co and Mn with stable structures in the high-nickel cathode material, during the cycling process, due to internal shrinkage and expansion, stress is prone to concentrate, and the particles are prone to cracking and pulverization starting from the particle surface during rolling and cycling, resulting in the exposure of fresh interfaces, which will consume the electrolyte, and at the same time problems such as cycling dives, increased internal resistance, and battery bulging occur. Therefore, improving the structural stability of the high-nickel cathode material is particularly important.

[0004] Currently, the structural stability of high-nickel cathode materials is mainly improved by doping. For example, the patent application document CN114538532A discloses a preparation method of a high-nickel ternary cathode material, which includes the following steps: (1) mixing a precursor containing a ternary cathode material with a lithium source evenly, and then compacting the mixed material. The ratio of the volume of the compacted mixed material to the volume of the mixed material in the natural state is 1 / 4 to 1:1; (2) subjecting the mixed material compacted in step (1) to low-temperature sintering in an oxygen atmosphere to obtain a low-temperature sintering product; the low-temperature sintering temperature is 550 to 650 °C and the sintering time is 3 to 8 h; (3) mixing the low-temperature sintering product and an additive evenly, and then subjecting it to high-temperature sintering in an oxygen atmosphere, followed by cooling, grinding, and sieving to obtain a doped and modified high-nickel ternary cathode material; the high-temperature sintering temperature is 700 to 950 °C and the sintering time is 8 to 15 h.

[0005] For another example, patent application document CN109904432A discloses a W-doped modified high-nickel ternary cathode material, which is prepared by the following method: Step (1): Add LiOH·H2O to a mortar and dry grind for 3-5 min, then add a nickel cobalt manganese oxide precursor and a tungsten source and mix evenly, dry grind for 10-30 min, and then add ethanol to submerge the mixture of the nickel cobalt manganese oxide precursor and the tungsten source, and wet grind for 30-40 min to obtain a solid powder; Step (2): First pre-calcine the solid powder in an oxygen atmosphere at 455°C - 550°C for 6-8 hours, then raise the temperature to 700°C - 850°C and keep it calcined for 12-18 hours. The heating rates in the pre-calcination and calcination stages are independently 3-5°C / min. After cooling, a W-doped modified high-nickel ternary cathode material is obtained; wherein, the molar ratio of nickel, cobalt, and manganese in the nickel cobalt manganese hydroxide precursor is x:y:(1-x-y), 0.6 < x < 1, 0 < y < 1, 0 < 1-x-y < 1; the mass ratio of the tungsten source to the nickel cobalt manganese oxide precursor is 0.005-0.02:1.

[0006] However, the doping involved in the high-nickel cathode materials in the prior art is all uniform surface doping, which cannot simultaneously improve the structural stability inside and on the surface of the high-nickel cathode material. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems in the prior art to some extent. To this end, an embodiment of the present invention provides a high-nickel cathode material, a preparation method thereof, and a lithium-ion battery.

[0008] The high-nickel cathode material of the embodiment of the present invention includes a core and a shell layer coated on the surface of the core. The core includes Li z Ni x Co y A 1-x-y O2 particles and D element doped in the whole of the Li z Ni x Co y A 1-x-y O2 particles, and E element doped in the surface layer of the Li z Ni x Co y A 1-x-y O2 particles. The surface layer starts from the surface of the Li z Ni x Co y A 1-x-y O2 particles to a distance from the Li z Ni x Co y A 1-x-yThe region between 1-5 nm from the surface of the O2 particles, where 0.80 ≤ x < 1.00, 0 ≤ y < 0.20, 0.96 ≤ z ≤ 1.10, 0 < 1 - x - y; A is selected from Mn and / or Al; D is selected from at least one of Al, Ti, Zr, and Mg; E is selected from at least one of Ta, Nb, Ge, Y, W, Ce, Sr, and Mo; the shell layer includes a fast ion conductor coating layer, and the coating elements of the fast ion conductor coating layer are selected from at least one of B, Al, Ti, Nb, W, and Zr.

[0009] The advantages and technical effects brought by the high-nickel cathode material of the embodiments of the present invention are as follows:

[0010] 1. The core includes Li z Ni x Co y A 1-x-y O2 particles, where 0.80 ≤ x < 1.00, 0 ≤ y < 0.20, 0.96 ≤ z ≤ 1.10, 0 < 1 - x - y, so that the high-nickel cathode material has the advantages of high safety performance, high specific capacity, and stable cycling performance.

[0011] 2. D is selected from at least one of Al, Ti, Zr, and Mg, which belongs to elements with low radius and high activity, and is distributed throughout the Li z Ni x Co y A 1-x-y O2 particles, thus ensuring the structural stability and cycling performance of the cathode material.

[0012] 3. E is selected from at least one of Ta, Nb, Ge, Y, W, Ce, Sr, and Mo, which belongs to elements with high radius and low activity, and is distributed on the surface layer of the Li z Ni x Co y A 1-x-y O2 particles, which can effectively improve the interfacial structural stability and cycling performance of the high-nickel cathode material; at the same time, the E element with high radius and low activity can effectively prevent the excessive fusion and growth of the primary particles of the high-nickel cathode material, which is beneficial to the preparation of high-nickel cathode materials with smaller primary particle sizes, and thus is beneficial to improving the rate performance of the high-nickel cathode material.

[0013] 4. The shell layer includes a fast ion conductor coating layer, so that the coating elements of the fast ion conductor coating layer are enriched on the surface of the core, which is beneficial to improving the diffusion rate of interfacial lithium ions and the rate performance of the high-nickel cathode material. At the same time, the fast ion conductor coating layer can effectively isolate the direct contact between the core and the electrolyte, reduce interfacial side reactions, and is beneficial to improving the cycling stability of the high-nickel cathode material.

[0014] 5. In summary, element D with a low radius and high activity is uniformly distributed in Li z Ni x Co y A 1-x-y In the overall O2 particles, element E with a high radius and low activity is enriched in Li z Ni x Co y A 1-x-y On the surface layer of the O2 particles, the coating elements of the fast ion conductor coating layer are enriched in Li z Ni x Co y A 1-x-y On the surface of the O2 particles, the above distribution state is called a gradient distribution, and this gradient distribution can effectively improve the structural stability and cycling performance of the high-nickel cathode material.

[0015] In some embodiments, based on the total mass of the high-nickel cathode material being 100%, the content of A2 is 2000 - 5000 ppm; the content of A3 is 1000 - 3000 ppm; the content of the coating elements of the fast ion conductor coating layer is 1000 - 3000 ppm.

[0016] In some embodiments, the fast ion conductor coating layer is selected from at least one of lithium borate, lithium metaaluminate, lithium titanate, lithium niobate, lithium tungstate, and lithium zirconate.

[0017] The preparation method of the high-nickel cathode material according to the embodiment of the present invention includes the following steps:

[0018] (1) Mix the high-nickel cathode material precursor doped with element D, a lithium salt, and an additive containing element E, and then perform a first sintering in an oxidizing atmosphere to obtain the core;

[0019] (2) Mix the core and an additive containing coating elements, and then perform a second sintering in an oxidizing atmosphere to obtain the high-nickel cathode material.

[0020] The advantages and technical effects brought by the preparation method of the high-nickel cathode material according to the embodiment of the present invention are:

[0021] 1. In step (1), the high-nickel cathode material precursor doped with element D is used, which can ensure from the process that element D with a low radius and high activity is uniformly doped in Li z Ni x Co y A 1-x-y In the overall O2 particles, thereby ensuring an effective improvement in the structural stability and cycling performance of the high-nickel cathode material.

[0022] 2. In the first sintering process of step (1), doping is carried out using an additive containing element E. Element E belongs to elements with a high radius and low activity, and it is relatively difficult to dope this type of element into the Li z Ni x Co y A 1-x-y O2 particles. More of it is doped into the Li z Ni x Co y A 1-x-y O2 particle surface layer. Therefore, during the first sintering process, the doping element E realizes uniform doping of the Li z Ni x Co y A 1-x-y O2 particle surface layer through atomic thermal diffusion. This can effectively improve the interfacial structure stability and cycling performance of the high-nickel cathode material; at the same time, the high-radius and low-activity element E can also effectively prevent the excessive fusion and growth of the primary particles of the high-nickel cathode material, which is beneficial to the preparation of high-nickel cathode materials with smaller primary particle sizes, and thus beneficial to improving the rate performance of the high-nickel cathode material.

[0023] 3. In step (2), the coating elements of the fast ion conductor coating layer are introduced through an additive containing coating elements. After the second sintering, the additive containing coating elements forms a fast ion conductor coating layer on the core surface. The fast ion conductor coating layer is beneficial to improving the diffusion rate of interfacial lithium ions and enhancing the rate performance of the high-nickel cathode material. At the same time, the fast ion conductor coating layer can effectively isolate the direct contact between Li z Ni x Co y A 1-x-y O2 and the electrolyte, reducing interfacial side reactions and being beneficial to improving cycling stability.

[0024] 4. In summary, through the above step-by-step doping and coating of the fast ion conductor coating layer, the low-radius and high-activity element D is uniformly doped in the overall Li z Ni x Co y A 1-x-y O2 particles, the high-radius and low-activity element E is uniformly enriched on the surface layer of the Li z Ni x Co y A 1-x-y O2 particles, and the coating elements of the fast ion conductor coating layer are enriched on the Li z Ni x Co y A 1-x-y O2 surface. This distribution is called a gradient distribution, and this gradient distribution can effectively improve the structural stability and cycling performance of the high-nickel cathode material.

[0025] 5. The preparation method of the embodiment of the present invention has a simple process and is suitable for large-scale production.

[0026] In some embodiments, the additive containing element E is selected from at least one of tantalum oxide, niobium oxide, germanium oxide, yttrium oxide, tungsten oxide, cerium oxide, strontium oxide, and molybdenum oxide; and / or, the additive containing the coating element is selected from at least one of boric acid, metaaluminum acid, titanic acid, niobic acid, tungstic acid, and zirconic acid.

[0027] In some embodiments, the temperature of the first sintering is 700 - 900 °C, and the heat preservation time of the first sintering is 3 - 10 h; and / or, the temperature of the second sintering is 300 - 600 °C, and the heat preservation time of the second sintering is 2 - 6 h.

[0028] In some embodiments, step (1) includes the following steps: mixing the high-nickel cathode material precursor doped with element D and the lithium salt, and performing pre-sintering in an oxidizing atmosphere to obtain a pre-sintered material; then mixing the pre-sintered material and the additive containing element E and performing the first sintering to obtain the core.

[0029] In some embodiments, after the first sintering, crushing, washing, separation, and drying are performed to obtain the core.

[0030] In some embodiments, the temperature of the pre-sintering is 400 - 600 °C, and the heat preservation time of the pre-sintering is 3 - 10 h.

[0031] In addition, the embodiment of the present invention also provides a lithium-ion battery, including the high-nickel cathode material of the embodiment of the present invention or the high-nickel cathode material obtained by the preparation method of the embodiment of the present invention.

[0032] The advantages and technical effects brought by the lithium-ion battery of the embodiment of the present invention are as follows:

[0033] Due to the adoption of the high-nickel cathode material of the embodiment of the present invention or the high-nickel cathode material obtained by the preparation method of the embodiment of the present invention, the lithium-ion battery of the embodiment of the present invention has excellent cycle stability and rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a scanning electron microscope photograph (SEM) of the high-nickel cathode material prepared in Example 1 of the present invention;

[0035] Figure 2 is a transmission electron microscope photograph (TEM) of the high-nickel cathode material prepared in Example 1 of the present invention;

[0036] Figure 3It is a scanning electron microscope photograph (SEM) of the high-nickel cathode material prepared in Comparative Example 2 of the present invention. Detailed implementation manners

[0037] The embodiments of the present invention will be described in detail below. The examples are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0038] The embodiments of the present invention provide a high-nickel cathode material, including a core and a shell layer coated on the surface of the core. The core includes Li z Ni x Co y A 1-x-y O2 particles and D element doped in the whole Li z Ni x Co y A 1-x-y O2 particles, and E element doped in the surface layer of the Li z Ni x Co y A 1-x-y O2 particles. The surface layer is the area starting from the surface of the Li z Ni x Co y A 1-x-y O2 particles to a distance of 1-5 nm from the surface of the Li z Ni x Co y A 1-x-y O2 particles. Among them, 0.80 ≤ x < 1.00, 0 ≤ y < 0.20, 0.96 ≤ z ≤ 1.10, 0 < 1 - x - y; A is selected from Mn and / or Al; D is selected from at least one of Al, Ti, Zr, and Mg; E is selected from at least one of Ta, Nb, Ge, Y, W, Ce, Sr, and Mo; the shell layer includes a fast ion conductor coating layer, and the coating element of the fast ion conductor coating layer is selected from at least one of B, Al, Ti, Nb, W, and Zr.

[0039] The D element with a low radius and high activity is uniformly distributed in the whole Li z Ni x Co y A 1-x-y O2 particles. The E element with a high radius and low activity is enriched in the surface layer of the Li z Ni x Co y A 1-x-y O2 particles. The coating element of the fast ion conductor coating layer is enriched in the Li z Ni x Coy A 1-x-y On the surface of O2, the above distribution state is called gradient distribution, and this gradient distribution can effectively improve the structural stability and cycling performance of the high-nickel cathode material. If element D is not doped or element D is doped in Li in the same way as element E z Ni x Co y A 1-x-y On the surface layer of O2 particles, it is difficult to improve the structural stability inside the high-nickel cathode body. If element E is not doped or element E is not doped in Li z Ni x Co y A 1-x-y On the surface layer of O2 particles, it is also difficult to improve the interfacial structural stability and cycling performance of the high-nickel cathode material. If the fast ion conductor coating layer is not formed, the direct contact between the electrolyte and the cathode cannot be isolated by the fast ion conductor coating layer, which will significantly increase the interfacial side reactions and reduce the lithium ion conduction at the interface.

[0040] In some embodiments, based on the total mass of the high-nickel cathode material being 100%, the content of element D is 2000 - 5000 ppm; the content of element E is 1000 - 3000 ppm; the content of the coating element of the fast ion conductor coating layer is 1000 - 3000 ppm. When the contents of element D, element E and the coating element of the fast ion conductor coating layer are within the above ranges, it helps to improve the structural stability and cycling performance of the high-nickel cathode material.

[0041] In some embodiments, the fast ion conductor coating layer is selected from at least one of lithium borate, lithium metaaluminate, lithium titanate, lithium niobate, lithium tungstate and lithium zirconate.

[0042] In addition, the embodiment of the present invention also provides a preparation method of a high-nickel cathode material, including the following steps:

[0043] (1) Mix the precursor of the high-nickel cathode material doped with element D, a lithium salt and an additive containing element E, and then perform the first sintering in an oxidizing atmosphere to obtain the core;

[0044] (2) Mix the core and an additive containing the coating element, and then perform the second sintering in an oxidizing atmosphere to obtain the high-nickel cathode material.

[0045] In step (1), element D can form a high-nickel cathode material precursor doped with element D through a co-deposition method. The specific method can refer to the prior art and will not be elaborated here. Element D is an element with a low radius and high activity, such as at least one of Al, Ti, Zr, and Mg. Element D is uniformly distributed from the inside to the outside in the high-nickel cathode material precursor, which has an obvious effect on improving the internal structure stability and cycling performance of the high-nickel cathode material. In addition, in step (1), the high-nickel cathode material precursor doped with element D, a lithium salt, and an additive containing element E are mixed and then sintered for the first time. The doping element E provided by the additive containing element E, such as at least one of Ta, Nb, Ge, Y, W, Ce, Sr, and Mo, will be doped into the surface layer of the Li z Ni x Co y A 1-x-y O2 particles, which can improve the interface structure stability and cycling performance of the high-nickel cathode material. In addition, in step (2), the core and an additive containing a coating element are mixed and then sintered for the second time to form a fast ion conductor coating layer on the surface of the core, which can improve the rate performance and cycling performance of the high-nickel cathode material.

[0046] In summary, through the above step-by-step doping and coating with a fast ion conductor coating layer, the low-radius and high-activity element D is uniformly doped in the overall Li z Ni x Co y A 1-x-y O2 particles, the high-radius and low-activity element E is uniformly enriched in the surface layer of the Li z Ni x Co y A 1-x-y O2 particles, and the coating element of the fast ion conductor coating layer is enriched on the surface of the Li z Ni x Co y A 1-x-y O2 particles. This distribution is called a gradient distribution, and this gradient distribution can effectively improve the structure stability and cycling performance of the high-nickel cathode material.

[0047] In some embodiments, the chemical formula of the high-nickel cathode material precursor is Ni x Co y A 1-x-y (OH)2, where 0.80 ≤ x < 1.00, 0 ≤ y < 0.20, 0.96 ≤ z ≤ 1.10, 0 < 1 - x - y; A is selected from Mn and / or Al. The lithium salt is lithium hydroxide and / or lithium carbonate.

[0048] In some embodiments, the lithium salt is a micronized lithium salt, and the median particle size D50 of the micronized lithium salt is 5 - 30 μm. When the median particle size D50 of the micronized lithium salt is too high, that is, the particles of the micronized lithium salt are too large, it is not conducive to the complete reaction between the micronized lithium salt and the precursor of the high-nickel cathode material doped with element D.

[0049] In some embodiments, the molar ratio of the precursor of the high-nickel cathode material doped with element D to the molar amount of lithium in the lithium salt is 1:(1.02 - 1.1). The excess of the lithium salt is to ensure the complete reaction between the precursor of the high-nickel cathode material doped with element D and the lithium salt, and to avoid waste of the precursor of the high-nickel cathode material doped with element D.

[0050] In some embodiments, the additive containing element E is selected from at least one of tantalum oxide, niobium oxide, germanium oxide, yttrium oxide, tungsten oxide, cerium oxide, strontium oxide, and molybdenum oxide. After the first sintering, the above-mentioned additive containing element E enables the high-radius and low-activity element E to be doped in the surface layer of the Li z Ni x Co y A 1-x-y O2 particles, which is beneficial to improving the interface structure stability and cycling performance of the high-nickel cathode material. Moreover, the high-radius and low-activity element E can also effectively prevent the excessive fusion and growth of the primary particles of the cathode material, which is beneficial to the preparation of high-nickel cathode materials with smaller primary particle sizes, and thus is beneficial to improving the rate performance of the high-nickel cathode material.

[0051] In some embodiments, the temperature of the first sintering is 700 - 900 °C, such as 700 °C, 720 °C, 740 °C, 760 °C, 780 °C, 800 °C, 820 °C, 840 °C, 860 °C, 880 °C, 900 °C, etc., and the heat preservation time of the first sintering is 3 - 10 h, such as 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc. When the temperature of the first sintering is too low and / or the heat preservation time is too short, it is not conducive to the infiltration of element E into the surface layer structure of the Li z Ni x Co y A 1-x-y O2 particles, resulting in too low doping amount of element E, which is not conducive to improving the interface structure stability and cycling performance of the high-nickel cathode material. When the temperature of the first sintering is too high and / or the heat preservation time is too long, the improvement effect of the doping effect of element E on the surface layer of the Li z Ni x Co y A 1-x-y O2 particles is not obvious, and it is not conducive to cost reduction and efficiency improvement instead.

[0052] In some embodiments, the additive containing a coating element is selected from at least one of boric acid, meta-aluminum acid, titanic acid, niobic acid, tungstic acid, and zirconic acid. The fast ion conductor coating layer is formed after the second sintering of the above additive containing a coating element. The fast ion conductor coating layer is at least one of lithium borate, lithium meta-aluminate, lithium titanate, lithium niobate, lithium tungstate, lithium zirconate, etc. The above fast ion conductor coating layer can significantly improve the interfacial lithium ion conduction rate of the high-nickel cathode material, improve the fast charging performance of the battery, and in addition, can reduce the side reactions at the interface of the high-nickel cathode material and improve the cycle performance of the battery.

[0053] In the embodiments of the present invention, there is no particular limitation on the specific manner of mixing the core and the additive containing a coating element. It can be dry mixing or wet mixing, as long as the two are fully mixed. Preferably, the method of stirring and evaporation is adopted, the solvent is ethanol, the solid-liquid ratio is (0.5-1.5):1, the stirring speed is preferably 10-60 rpm, and the temperature is preferably 60-90 °C. The wet mixing has a more uniform mixing effect, and the formed fast ion conductor coating layer can better uniformly coat the surface of the core.

[0054] In some embodiments, the temperature of the second sintering is 300-600 °C, such as 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, etc., and the heat preservation time of the second sintering is 2-6 h, such as 2 h, 3 h, 4 h, 5 h, 6 h, etc. When the temperature of the second sintering is too low and / or the heat preservation time is too short, it is not conducive to the fast ion conductor coating layer coating on the surface of the core, and thus not conducive to improving the rate performance and cycle performance of the high-nickel cathode material. When the temperature of the second sintering is too high, it is not conducive to suppressing the diffusion of the coating elements of the fast ion conductor coating layer into the core, and thus not conducive to maintaining the effective crystal structure of the fast ion conductor, losing the meaning of the fast ion conductor coating.

[0055] In the preparation method of the embodiments of the present invention, the sintering atmosphere of the first sintering and the second sintering is an oxidizing atmosphere, such as air, pure oxygen, or a mixture of pure oxygen and inert gases such as N2, He, etc. The sintering atmosphere of the first sintering and the second sintering is preferably pure oxygen. Pure oxygen helps the smooth progress of the first sintering and the second sintering, and can avoid introducing impurities into the high-nickel cathode material.

[0056] In some embodiments, step (1) includes the following steps: mixing the high-nickel cathode material precursor doped with element D and a lithium salt, followed by pre-sintering to obtain a pre-sintered material; then mixing the pre-sintered material and the additive containing element E, and performing the first sintering to obtain the core. The pre-sintering technique can dehydrate and pre-react the high-nickel cathode material precursor doped with element D and the lithium salt at a low temperature, making their mixture more uniform, and the dehydrated mixture is lighter, which is beneficial to increasing the crucible loading amount during the first sintering process, improving the sintering productivity, and reducing costs.

[0057] In the preparation method of the embodiments of the present invention, there are no specific limitations on the mixing method of the high-nickel cathode material precursor doped with element D and the lithium salt, as well as the mixing method of the pre-sintered product and the additive containing element E, as long as the two can be mixed evenly. It is preferably stirred and mixed in a high-speed mixer; the stirring speed is preferably 1000 - 10000 rpm, and the stirring time is preferably 5 - 12 min.

[0058] In some embodiments, the temperature of the pre-sintering is 400 - 600 °C, such as 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, etc., and the heat preservation time of the pre-sintering is 3 - 10 h, such as 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc. When the temperature of the pre-sintering is too low and / or the time is too short, it is not conducive to removing the moisture in the high-nickel cathode material precursor doped with element D and the lithium salt, and improving the loose bulk density and productivity. When the temperature of the pre-sintering is too high and / or the time is too long, it is not conducive to cost reduction and efficiency improvement.

[0059] In the preparation method of the embodiments of the present invention, the atmosphere of the pre-sintering is an oxidizing atmosphere, for example, it can be air, pure oxygen, or a mixture of pure oxygen and inert gases such as N2, He, etc. The atmosphere of the pre-sintering is preferably pure oxygen. The above pre-sintering atmosphere helps the dehydration and pre-reaction to proceed, and at the same time can avoid introducing impurities into the high-nickel cathode material.

[0060] In some embodiments, whether or not pre-sintered, after the first sintering, it can be further crushed, washed with water, separated, and dried to obtain the core. Crushing is to reduce the particle size of the first sintering product and improve the subsequent battery processing performance, for example, reducing the coating particle feeling of the positive electrode paste and making the paste coating more uniform. Washing with water is to remove the excessive lithium salt and reduce the alkali content in the positive electrode material. On the one hand, it can better meet the subsequent cell manufacturing process control, for example, reducing the paste flocculation, and on the other hand, it can reduce the gas generation risk during the subsequent battery cycling and storage processes. Separation and drying are to remove the moisture in the first sintering product obtained after washing with water to obtain the core, which is convenient for the subsequent second sintering.

[0061] The preparation method of the embodiment of the present invention does not particularly limit the specific way of crushing, as long as the particles of the first sintered product can be reduced. It is preferred to first perform coarse crushing with a roll crusher and then perform fine crushing with a jet mill, which is beneficial to improving the crushing efficiency.

[0062] The preparation method of the embodiment of the present invention does not particularly limit the specific way of water washing, as long as the excessive lithium salt can be removed. In the process of the water washing, the water-to-material ratio is preferably (0.5 - 1.5):1, such as 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, etc.; the water washing time is preferably 1 - 10 min, such as 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.; the water washing temperature is preferably 15 - 45 °C, such as 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, etc.; during the process of the water washing, stirring is preferably carried out simultaneously, and the stirring speed is preferably 10 - 60 rpm, such as 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, etc. The above water washing process is more conducive to cleaning the excessive lithium salt thoroughly.

[0063] The preparation method of the embodiment of the present invention does not particularly limit the specific way of separation, as long as the water in the first sintered product after water washing can be removed. For example, at least one of filtration, pressure filtration, centrifugation, etc. can be adopted. It is preferred to adopt the way of pressure filtration, which is more conducive to removing water and reducing the time spent in the drying process.

[0064] The preparation method of the embodiment of the present invention does not particularly limit the specific way of drying, as long as the residual water in the first sintered product obtained after separation from water can be removed. The drying temperature is preferably 100 - 150 °C, such as 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, etc.; the drying time is preferably 2 - 10 h, such as 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, etc.

[0065] In some embodiments, the median particle size D50 of the core is 6 - 14 μm. When the median particle size D50 of the core is too small, the specific surface area of the core is too large, and there may be a risk of gas generation during the cycling and storage of the battery. When the median particle size D50 of the core is too large, it is not conducive to improving the battery processing performance. For example, there may be a sense of particles during the coating of the positive electrode slurry, which is not conducive to improving the uniformity of the slurry coating.

[0066] In addition, an embodiment of the present invention also provides a lithium-ion battery, including the high-nickel cathode material of the embodiment of the present invention or the high-nickel cathode material obtained by the preparation method of the embodiment of the present invention.

[0067] Due to the adoption of the high-nickel cathode material of the embodiment of the present invention or the high-nickel cathode material obtained by the preparation method of the embodiment of the present invention, the lithium-ion battery of the embodiment of the present invention has excellent cycle stability and rate performance.

[0068] The present invention will be described in detail below in conjunction with embodiments and drawings. For those not specifying specific experimental steps or conditions in the embodiments, the operations or conditions of the conventional experimental steps described in the literature in the art can be followed.

[0069] Example 1

[0070] A preparation method of a high-nickel ternary cathode material for a lithium-ion battery includes the following steps:

[0071] (1) Mix 20 Kg of a precursor Ni 0.83 Co 0.12 Mn 0.05 (OH)2 with an Al doping amount of 2000 ppm and a D50 of 7 μm and fine powder lithium hydroxide with a D50 of 5 μm in a molar ratio of Ni 0.83 Co 0.12 Mn 0.05 (OH)2:Li = 1:1.02 in a high-speed mixer and stir at 1000 rpm for 12 min. After the materials are mixed evenly, put them into a kiln for pre-sintering. The sintering temperature is 400 °C, the sintering holding time is 10 h, and the atmosphere is pure oxygen to obtain the pre-sintered materials.

[0072] (2) Mix the pre-sintered materials and 73 g of tantalum oxide in a high-speed mixer at 1000 rpm for 12 min. Sinter the mixed materials in a kiln for the first time. The sintering temperature is 700 °C, the sintering holding time is 10 h, and the sintering atmosphere is pure oxygen to obtain the first sintered materials. Crush the first sintered materials, control D50 at 6 μm, then wash them under the condition of a water-to-material ratio of 0.5:1 for 10 min. Control the washing temperature at 15 °C and the stirring rod speed at 10 rpm, then perform pressure filtration, and then dry at 100 °C for 10 h.

[0073] (3) Pour the dried first sintered materials and 114 g of H3BO3 into ethanol, control the solid-to-liquid ratio at 0.5:1, and stir at a speed of 10 rpm. Heat to 60 °C until it is evaporated to dryness. Place the evaporated mixture in a kiln and sinter it with pure oxygen for the second time. The sintering temperature is 300 °C, the sintering holding time is 6 h. After screening, iron removal, and packaging, the finished high-nickel ternary cathode material is obtained.

[0074] It should be noted that since the content of Al element doped in the precursor is extremely small and difficult to be reflected in the chemical formula, the chemical formula of the precursor is denoted as Ni 0.83 Co 0.12 Mn 0.05 (OH)2.

[0075] The high-nickel ternary cathode material prepared in this example consists of a core and a shell layer coated on the surface of the core. The core is composed of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and Al elements doped in the whole Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles, as well as Ta elements doped in the surface layer of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. The surface layer is the region between the surface of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and a distance of 1 - 5 nm from the surface of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. The shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Al is 2000 ppm, the mass fraction of Ta is 3000 ppm, and the mass fraction of B is 1000 ppm.

[0076] Example 2

[0077] A preparation method of a high-nickel ternary cathode material for lithium-ion batteries, comprising the following steps:

[0078] (1) 20 Kg of a precursor Ni 0.83 Co 0.12 Mn 0.05 (OH)2 with a D50 of 15 μm and an Al doping amount of 5000 ppm is taken according to Ni 0.83 Co 0.12 Mn 0.05(OH)2 and lithium hydroxide with a D50 of 30 μm were mixed at a molar ratio of 1:1.1 and stirred in a high-speed mixer at 10,000 rpm for 5 min. After the materials were evenly mixed, they were put into a kiln for pre-sintering. The sintering temperature was 600 °C, the holding time for sintering was 3 h, and pure oxygen was selected as the atmosphere to obtain the pre-sintered materials.

[0079] (2) The pre-sintered materials and 24 g of tantalum oxide were stirred and mixed in a high-speed mixer at 10,000 rpm for 5 min. The mixed materials were sintered for the first time in a kiln. The sintering temperature was 900 °C, the holding time for sintering was 3 h, and the sintering atmosphere was pure oxygen to obtain the first sintered materials. The first sintered materials were crushed, and the D50 was controlled at 14 μm. Then, they were washed with water under the condition of a water-to-material ratio of 1.5:1. The washing time was 1 min, the washing temperature was controlled between 45 °C, the rotation speed of the stirring rod was 60 rpm, and then they were pressure-filtered and dried at 150 °C for 2 h.

[0080] (3) The dried first sintered materials and 342 g of H3BO3 were poured into ethanol, and the solid-to-liquid ratio was controlled at 1.5:1. The stirring speed was 60 rpm, and it was heated to 90 °C until it was evaporated to dryness. The evaporated mixture was placed in a kiln and sintered for the second time with pure oxygen. The sintering temperature was 600 °C, and the sintering holding time was 2 h. After screening, iron removal, and packaging, the finished high-nickel ternary cathode material was obtained.

[0081] The high-nickel ternary cathode material prepared in this example consists of a core and a shell layer coated on the surface of the core. The core is composed of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and Al elements doped in the overall Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles, as well as Ta elements doped in the surface layer of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. The surface layer starts from the surface of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles to a distance from the surface of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05The region between 1 - 5 nm from the surface of the O2 particles; the shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Al is 5000 ppm, the mass fraction of Ta is 5000 ppm, and the mass fraction of B is 3000 ppm.

[0082] Example 3

[0083] A preparation method of a high-nickel ternary cathode material for lithium-ion batteries, comprising the following steps:

[0084] (1) Mix 20 Kg of a precursor Ni 0.83 Co 0.12 Mn 0.05 (OH)2 with an Al doping amount of 3000 ppm and a D50 of 10 μm and lithium hydroxide with a D50 of 20 μm according to the molar ratio of Ni 0.83 Co 0.12 Mn 0.05 (OH)2:Li = 1:1.05 in a high-speed mixer and stir at 5000 rpm for 7 min. After the materials are mixed evenly, put them into a kiln for pre-sintering. The sintering temperature is 400 °C, the sintering holding time is 5 h, and the atmosphere is pure oxygen to obtain the pre-sintered materials.

[0085] (2) Stir and mix the pre-sintered materials and 48 g of tantalum oxide in a high-speed mixer at 5000 rpm for 7 min. Sinter the mixed materials in a kiln for the first time. The sintering temperature is 800 °C, the time is 5 h, and the sintering atmosphere is pure oxygen to obtain the first sintered materials. Crush the first sintered materials, control D50 at 9 μm, then wash them under the condition of a water-to-material ratio of 1:1. The washing time is 1 min, the washing temperature is controlled between 45 °C, the rotation speed of the stirring rod is 60 rpm, then carry out pressure filtration and dry at 150 °C for 2 h.

[0086] (3) Pour the dried first sintered materials and 342 g of H3BO3 into ethanol, control the solid-to-liquid ratio at 1.5:1, the stirring speed at 60 rpm, and heat to 90 °C until it is evaporated to dryness. Place the evaporated mixture in a kiln and sinter it in pure oxygen for the second time. The sintering temperature is 600 °C, the sintering holding time is 2 h. After screening, iron removal, and packaging, the finished high-nickel ternary cathode material is obtained.

[0087] The high-nickel ternary cathode material prepared in this example consists of a core and a shell layer coated on the surface of the core. The core consists of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and doping in Li 1.02 Ni 0.83 Co0.12 Mn 0.05 The Al element in the whole MnO₂ particles and the doping in Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 The Ta element composition in the surface layer of the MnO₂ particles, and the surface layer is from Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 The region from the surface of the MnO₂ particles to a distance of 1 - 5 nm from the surface of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 The region between the surface of the MnO₂ particles and 1 - 5 nm from the surface of the MnO₂ particles; the shell layer is lithium borate (fast ion conductor coating layer). Taking the total mass of this high-nickel ternary cathode material as 100%, the mass fraction of Al is 3000 ppm, the mass fraction of Ta is 2000 ppm, and the mass fraction of B is 3000 ppm.

[0088] Example 4

[0089] The preparation method of the high-nickel ternary cathode material for lithium-ion batteries in this example is the same as that in Example 3, except that Ni 0.83 Co 0.12 Mn 0.05 (OH)₂ is replaced with Ni 0.90 Co 0.05 Mn 0.05 (OH)₂.

[0090] The high-nickel ternary cathode material prepared in this example consists of a core and a shell layer coated on the surface of the core. The core is composed of Li 1.05 Ni 0.90 Co 0.05 Mn 0.05 O₂ particles and the Al element doped in the whole Li 1.05 Ni 0.90 Co 0.05 Mn 0.05 O₂ particles and the Ta element doped in the surface layer of the Li 1.05 Ni 0.90 Co 0.05 Mn 0.05 O₂ particles, and the surface layer is from Li 1.05 Ni 0.90 Co 0.05 Mn 0.05 The region from the surface of the O₂ particles to a distance from the surface of Li 1.05 Ni 0.90 Co 0.05 Mn 0.05The region between 1 - 5 nm from the surface of the O2 particles; the shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Al is 3000 ppm, the mass fraction of Ta is 2000 ppm, and the mass fraction of B is 3000 ppm.

[0091] Example 5

[0092] The preparation method of the high-nickel ternary cathode material for lithium-ion batteries in this example is the same as that in Example 3, except that Ni 0.83 Co 0.12 Mn 0.05 (OH)2 is replaced with Ni 0.96 Co 0.03 Mn 0.02 (OH)2.

[0093] The high-nickel ternary cathode material prepared in this example consists of a core and a shell layer coated on the surface of the core. The core is composed of Li 1.05 Ni 0.96 Co 0.03 Mn 0.02 O2 particles and Al elements doped in the overall Li 1.05 Ni 0.96 Co 0.03 Mn 0.02 O2 particles, as well as Ta elements doped in the surface layer of Li 1.05 Ni 0.96 Co 0.03 Mn 0.02 O2 particles. The surface layer is from the surface of Li 1.05 Ni 0.96 Co 0.03 Mn 0.02 O2 particles up to the region between 1 - 5 nm from the surface of Li 1.05 Ni 0.96 Co 0.03 Mn 0.02 O2 particles; the shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Al is 3000 ppm, the mass fraction of Ta is 2000 ppm, and the mass fraction of B is 3000 ppm.

[0094] Comparative Example 1

[0095] The preparation method of the high-nickel ternary cathode material for lithium-ion batteries in this comparative example is the same as that in Example 1, except that the precursor Ni with an Al doping amount of 2000 ppm 0.83 Co 0.12 Mn 0.05(OH)2 is replaced with Ni without Al doping 0.83 Co 0.12 Mn 0.05 (OH)2.

[0096] The high-nickel ternary cathode material prepared in this comparative example consists of a core and a shell layer coated on the surface of the core. The core is composed of Li 1.02 Ni 0.83 Co 0.12 A 0.05 O2 particles and Ta elements doped in the surface layer of Li 1.02 Ni 0.83 Co 0.12 A 0.05 O2 particles. The surface layer is the region between 1 - 5 nm from the surface of Li 1.02 Ni 0.83 Co 0.12 A 0.05 O2 particles to the surface of Li 1.02 Ni 0.83 Co 0.12 A 0.05 O2 particles. The shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Ta is 2000 ppm, and the mass fraction of B is 3000 ppm.

[0097] Comparative Example 2

[0098] The preparation method of the high-nickel ternary cathode material for lithium-ion batteries in this comparative example is the same as that of Example 1, except that tantalum oxide is omitted.

[0099] The high-nickel ternary cathode material prepared in this comparative example consists of a core and a shell layer coated on the surface of the core. The core is composed of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and Al elements doped in the whole of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. The shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Al is 2000 ppm, and the mass fraction of B is 1000 ppm.

[0100] Comparative Example 3

[0101] The preparation method of the high-nickel ternary cathode material for lithium-ion batteries in this comparative example is the same as that of Example 1, except that H3BO3 is omitted.

[0102] The high-nickel ternary cathode material prepared in this comparative example consists of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and Al elements doped in the overall Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and Ta elements doped in the surface layer of the Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. The surface layer is the region from the surface of the Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles to a distance of 1 - 5 nm from the surface of the Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. Taking the total mass of this high-nickel ternary cathode material as 100%, the mass fraction of Al is 2000 ppm, and the mass fraction of Ta is 3000 ppm.

[0103] Comparative Example 4

[0104] The preparation method of the high-nickel ternary cathode material for lithium-ion batteries in this comparative example is the same as that of Example 1, except that the precursor Ni 0.83 Co 0.12 Mn 0.05 (OH)2 doped with 2000 ppm of Al is replaced with Ni 0.83 Co 0.12 Mn 0.05 (OH)2 without Al doping, and at the same time, 3000 ppm of tantalum oxide is replaced with a mixture of 3000 ppm of tantalum oxide and 2000 ppm of aluminum oxide.

[0105] The high-nickel ternary cathode material prepared in this comparative example consists of a core and a shell layer coated on the surface of the core. The core consists of Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles and Al elements and Ta elements doped in the surface layer of the Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 O2 particles. The surface layer is from the surface of the Li 1.02 Ni 0.83 Co 0.12 Mn0.05 The region between the surface of the O2 particles and a distance of 1 - 5 nm from the surface of the O2 particles to Li 1.02 Ni 0.83 Co 0.12 Mn 0.05 The region between the surface of the O2 particles and 1 - 5 nm from the surface of the O2 particles; the shell layer is lithium borate (fast ion conductor coating layer). Based on the total mass of the high-nickel ternary cathode material being 100%, the mass fraction of Al is 2000 ppm, the mass fraction of Ta is 3000 ppm, and the mass fraction of B is 1000 ppm.

[0106] Performance testing

[0107] 1. Morphology: Scanning electron microscope photos of the high-nickel cathode materials prepared in Examples 1 - 5 and Comparative Examples 1 - 4.

[0108] 2. Electrochemical performance test after making the high-nickel cathode materials prepared in Examples 1 - 5 and Comparative Examples 1 - 4 into lithium-ion batteries: Using the above cathode materials as samples, with N-methylpyrrolidone as a dispersant, the sample powder, conductive carbon black, and polyvinylidene fluoride are stirred evenly in a mass ratio of 90:5:5 and then coated on the surface of a clean aluminum foil, and scraped into a film. After drying in a blast dryer, an electrode sheet is obtained, punched into a circular sheet with a diameter of 8 mm, and further dried in a vacuum oven at 120 °C for 6 h to remove moisture. The prepared electrode sheet is used as the working electrode of a half-cell, metallic lithium is used as the counter electrode, and 1 mol / L LiPF6 / ethylene carbonate (EC)-dimethyl carbonate (DMC) (mass ratio of EC and DMC is 1:1) is used as the electrolyte. The battery is assembled in a glove box and the battery is subjected to charge and discharge tests, with the voltage range being 2.5 - 4.3 V, where the charge and discharge current densities are 0.1 C, 1 C, and 4 C.

[0109] Figure 1 Is the scanning electron microscope photo (SEM) of the high-nickel cathode material prepared in Example 1 of the present invention; Figure 2 Is the transmission electron microscope photo (TEM image) of the high-nickel cathode material prepared in Example 1 of the present invention; Figure 3 Is the scanning electron microscope photo (SEM) of the high-nickel cathode material prepared in Comparative Example 2 of the present invention. From Figure 1 It can be seen that the surface of the high-nickel cathode material particles prepared in Example 1 is smooth and there is no agglomeration phenomenon. From Figure 2 It can be seen that the high-nickel cathode material particles prepared in Example 1 are of a core-shell structure. From Figure 3 It can be seen that since the additive containing element E was not added in the second sintering process in Comparative Example 1, the particle size of the primary particles of the high-nickel cathode material prepared in Comparative Example 2 is significantly larger than that of the primary particles of the high-nickel cathode material in Example 1.

[0110] Table 1. Electrochemical performance test results of lithium-ion batteries assembled with the high-nickel cathode materials prepared in Examples 1-5 and Comparative Examples 1-4.

[0111]

[0112] As can be seen from Table 1, the 100-cycle retention rates of the high-nickel cathode materials prepared in Example 1 are higher than those of Comparative Examples 1, 2, and 3, and the discharge specific capacities at 1C and 4C are higher than those of Comparative Examples 1 and 2. This shows that the gradient distribution structure in the high-nickel cathode materials of the embodiments of the present invention is beneficial to improving the cycle stability and rate performance of the materials.

[0113] In addition, from the comparison between Example 1 and Comparative Example 4 in Table 1, it can be found that when both Element D and Element E are enriched on the surface layer of the core structure of the high-nickel cathode material and no Element D is doped into the core structure of the high-nickel cathode material, it is not conducive to improving the internal structure stability and cycle performance of the high-nickel cathode material.

[0114] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0115] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-nickel cathode material, characterized in that, It includes a core and a shell layer coated on the surface of the core. The core includes Li z Ni x Co y A 1-x-y O2 particles and D element doped in the whole of the Li z Ni x Co y A 1-x-y O2 particles, and E element doped in the surface layer of the Li z Ni x Co y A 1-x-y O2 particles. The surface layer is the region between 1 - 5 nm from the surface of the Li z Ni x Co y A 1-x-y O2 particle surface to the surface of the Li z Ni x Co y A 1-x-y O2 particle surface. Wherein, 0.80 ≤ x < 1.00, 0 ≤ y < 0.20, 0.96 ≤ z ≤ 1.10, 0 < 1 - x - y; A is selected from Mn and / or Al; D is selected from at least one of Al, Ti, Zr, and Mg; E is selected from at least one of Ta, Nb, Ge, Y, W, Ce, Sr, and Mo; the shell layer includes a fast ion conductor coating layer, and the coating element of the fast ion conductor coating layer is selected from at least one of B, Al, Ti, Nb, W, and Zr.

2. The high-nickel cathode material according to claim 1, wherein Based on the total mass of the high-nickel cathode material being 100%, the content of element D is 2000 - 5000 ppm; the content of element E is 1000 - 3000 ppm; the content of the coating elements of the fast ion conductor coating layer is 1000 - 3000 ppm.

3. The high-nickel cathode material according to claim 1 or 2, characterized in that, The fast ion conductor coating layer is selected from at least one of lithium borate, lithium metaaluminate, lithium titanate, lithium niobate, lithium tungstate, and lithium zirconate.

4. The preparation method of the high-nickel cathode material according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Mix the precursor of the high-nickel cathode material doped with element D, a lithium salt, and an additive containing element E, and then perform the first sintering in an oxidizing atmosphere to obtain the core; (2) Mix the core and an additive containing the coating elements, and then perform the second sintering in an oxidizing atmosphere to obtain the high-nickel cathode material.

5. The preparation method of the high-nickel cathode material according to claim 4, wherein The additive containing element E is selected from at least one of tantalum oxide, niobium oxide, germanium oxide, yttrium oxide, tungsten oxide, cerium oxide, strontium oxide, and molybdenum oxide; and / or, the additive of the coating elements is selected from at least one of boric acid, metaaluminum acid, titanic acid, niobic acid, tungstic acid, and zirconic acid.

6. The preparation method of the high-nickel cathode material according to claim 4, characterized in that, The temperature of the first sintering is 700 - 900 °C, and the heat preservation time of the first sintering is 3 - 10 h; and / or, the temperature of the second sintering is 300 - 600 °C, and the heat preservation time of the second sintering is 2 - 6 h.

7. The preparation method of the high-nickel cathode material according to claim 4, characterized in that, Step (1) includes the following steps: Mix the precursor of the high-nickel cathode material doped with element D and the lithium salt, and then perform pre-sintering in an oxidizing atmosphere to obtain a pre-sintered material; then mix the pre-sintered material and the additive containing element E and perform the first sintering to obtain the core.

8. The preparation method of the high-nickel cathode material according to claim 4 or 7, characterized in that, After the first sintering, perform crushing, water washing, separation, and drying to obtain the core.

9. The preparation method of the high-nickel cathode material according to claim 7, wherein The temperature of the pre-sintering is 400 - 600 °C, and the heat preservation time of the pre-sintering is 3 - 10 h.

10. A lithium-ion battery, comprising the high-nickel cathode material according to any one of claims 1 - 3 or the high-nickel cathode material obtained by the preparation method according to any one of claims 4 - 9.

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