An ultrahigh-nickel ternary hydroxide precursor, a positive electrode material and a preparation method

Abstract

The application provides a kind of superhigh nickel ternary precursor, positive electrode material and preparation method, the preparation method includes: in bottom liquid and flow into nickel cobalt manganese mixed salt solution, precipitant solution and complexing agent solution carry out coprecipitation reaction, obtain the superhigh nickel ternary precursor;The coprecipitation reaction, gradually reduce stirring speed with the increase of particle size;The coprecipitation reaction, stirring speed is reduced at least 7 times.The spherical degree of superhigh nickel ternary precursor prepared by the application is high, the particle size distribution is uniform, the tap density is high, and the corresponding positive electrode material has higher rate performance and cycle capacity retention rate.

Description

Technical Field

[0001] This invention belongs to the field of battery material technology, and relates to an ultra-high nickel ternary precursor, cathode material and preparation method. Background Technology

[0002] Ultra-high nickel ternary cathode materials (such as LiNi) 0.96 Co 0.02 Mn 0.02 O2 has become a research hotspot for next-generation lithium-ion battery cathode materials due to its high energy density. The electrochemical performance of these materials is closely related to the morphology, particle size distribution, sphericity, and structural integrity of their precursors. Co-precipitation is the mainstream method for preparing nickel-cobalt-manganese hydroxide precursors. By controlling process parameters such as pH, ammonia concentration, and temperature, metal ions are uniformly precipitated under alkaline conditions to form precursor particles.

[0003] Traditional co-precipitation methods (i.e., densification methods) typically involve simultaneous nucleation and growth in a single reactor. The resulting precursors often suffer from irregular morphology, low sphericity, and a tendency to form twins and multi-headed structures. These morphological defects can lead to microcracks and uneven lithium diffusion during subsequent high-temperature solid-state reactions, thereby reducing the battery's cycle stability and rate performance. Particularly in ultra-high nickel systems (nickel content ≥90%), the hydrolysis behavior of nickel ions is more complex and more sensitive to synthesis conditions, making it difficult for traditional methods to simultaneously achieve a balance between high sphericity, narrow particle size distribution, and high tap density.

[0004] CN111196613A discloses a technical solution to improve the sphericity of precursors by preparing high-sphericity seed crystals and using them in continuous reactions. However, this method does not systematically study the correlation between seed crystal size and final product morphology, nor does it provide a detailed scheme for staged stirring speed control. CN113329975A discloses a method of adding seed crystals during the growth stage to adjust the particle size distribution. Although this method improves batch consistency, it does not provide an effective solution for the twinning and multi-head structure problems common in ultra-high nickel systems. CN114150378A discloses a method to improve sphericity by controlling seed crystal size and growth rate, but its process window is narrow and its adaptability to industrial-scale (e.g., reactors with a capacity of 200L or more) is insufficient.

[0005] Furthermore, existing technologies typically employ constant stirring speeds or simple two-stage speed regulation for stirring rate control, failing to effectively match the particle growth process. In the early stages of particle growth, higher stirring speeds are required to ensure uniform mass transfer and consistent nucleation; however, in the later stages, excessively high stirring speeds can lead to large particle breakage or irregular growth. Therefore, developing a staged stirring rate control strategy that matches the particle growth process is of great significance for improving the morphological consistency of ultra-high nickel precursors. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an ultra-high nickel ternary precursor, a cathode material, and a preparation method. The ultra-high nickel ternary precursor prepared by the present invention has high sphericity, uniform particle size distribution, and high tap density, and the corresponding cathode material has high rate performance and cycle capacity retention.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing an ultra-high nickel ternary precursor, the method comprising:

[0009] A nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into the bottom solution to carry out a co-precipitation reaction, thereby obtaining the ultra-high nickel ternary precursor Ni. x Co y Mn z (OH)2, where x+y+z=1, x≥0.9, 0.01≤y≤0.09, 0.01≤z≤0.09;

[0010] During the coprecipitation reaction, the stirring speed is gradually reduced as the particle size increases;

[0011] During the coprecipitation reaction, the stirring speed is reduced at least 7 times.

[0012] The preparation method provided by this invention matches the particle growth process by repeatedly reducing the stirring speed during the co-precipitation process. This ensures the uniformity of the nucleation stage while avoiding the breakage and irregular growth of large particles during the growth stage. Compared with a constant stirring speed, the staged stirring speed control can significantly improve the morphology and electrochemical performance of the precursor. Moreover, the preparation method provided by this invention has the advantages of simple process, good reproducibility, and applicability to industrial production.

[0013] In some embodiments, the temperature of the coprecipitation reaction is 40°C to 70°C.

[0014] In some embodiments, the pH value of the coprecipitation reaction is 9.7 to 11.2.

[0015] In some embodiments, the concentration of the complexing agent during the coprecipitation reaction is 3 g / L to 6.5 g / L.

[0016] In some embodiments, the precipitant in the precipitant solution includes sodium hydroxide and / or potassium hydroxide.

[0017] In some embodiments, the complexing agent solution includes ammonia.

[0018] In some embodiments, the nickel-cobalt-manganese mixed salt solution includes nickel salt, cobalt salt, and manganese salt;

[0019] The nickel salt includes any one or a combination of at least two of nickel sulfate, nickel nitrate, or nickel chloride;

[0020] The cobalt salt includes any one or a combination of at least two of cobalt sulfate, cobalt nitrate, or cobalt chloride.

[0021] The manganese salt includes any one or a combination of at least two of manganese sulfate, manganese nitrate, or manganese chloride.

[0022] In some embodiments, the total metal ion concentration in the nickel-cobalt-manganese mixed salt solution is 80 g / L to 120 g / L.

[0023] In some embodiments, the coprecipitation reaction method is a densification method, and the stirring speed is gradually reduced as the particle size increases, including: the initial densification stirring speed is 300 rpm to 350 rpm, and the stirring speed is gradually reduced as the particle size increases. When the median particle size D50 reaches 10 μm to 12 μm, the stirring speed is reduced to 150 rpm to 220 rpm, and the reaction is carried out to the target particle size.

[0024] In some embodiments, the coprecipitation reaction is a densification process, in which the stirring speed is gradually reduced as the particle size increases. This includes: an initial densification stirring speed of 300-350 rpm; reducing the stirring speed to 280-320 rpm when the median particle size D50 reaches 4.3-4.7 μm; reducing the stirring speed to 260-300 rpm when the median particle size D50 reaches 5.3-5.7 μm; and reducing the stirring speed to 250 rpm when the median particle size D50 reaches 6.3-6.7 μm. When the median particle size D50 reaches 7.3μm~7.7μm, reduce the stirring speed to 220rpm~250rpm; when the median particle size D50 reaches 8.3μm~8.7μm, reduce the stirring speed to 200rpm~240rpm; when the median particle size D50 reaches 9.3μm~9.7μm, reduce the stirring speed to 180rpm~220rpm; when the median particle size D50 reaches 9.9μm~10.1μm, reduce the stirring speed to 150rpm~200rpm, and react to the target particle size.

[0025] In some embodiments, the coprecipitation reaction method is a seed method, and the stirring speed is gradually reduced as the particle size increases, including: preparing seed crystals with a median particle size D50 of 3μm to 5μm under the condition of 350rpm to 400rpm, and then carrying out the growth process in the presence of seed crystals;

[0026] The growth process includes: the initial seed crystal stirring speed is 280 rpm to 320 rpm, and the stirring speed is gradually reduced as the particle size increases. When the median particle size D50 reaches 10 μm to 12 μm, the stirring speed is reduced to 100 rpm to 150 rpm, and the reaction is carried out to the target particle size.

[0027] In some embodiments, the coprecipitation reaction method is a seed method, and the stirring speed is gradually reduced as the particle size increases, including: preparing seed crystals with a median particle size D50 of 3μm to 5μm under the condition of 350rpm to 400rpm, and then carrying out the growth process in the presence of seed crystals;

[0028] The growth process includes: initially stirring the seed crystals at 280 rpm to 320 rpm; reducing the stirring speed to 260 rpm to 300 rpm when the median particle size D50 reaches 4.8 μm to 5.2 μm; further reducing the stirring speed to 240 rpm to 270 rpm when the median particle size D50 reaches 6.3 μm to 6.7 μm; and finally reducing the stirring speed to 200 rpm to 240 rpm when the median particle size D50 reaches 7.3 μm to 7.7 μm. When the median particle size (D50) reaches 7.8 μm to 8.2 μm, reduce the stirring speed to 180 rpm to 200 rpm. When the median particle size (D50) reaches 8.8 μm to 9.2 μm, reduce the stirring speed to 150 rpm to 180 rpm. When the median particle size (D50) reaches 9.3 μm to 9.6 μm, reduce the stirring speed to 120 rpm to 150 rpm. When the median particle size (D50) reaches 9.8 μm to 10.2 μm, reduce the stirring speed to 100 rpm to 120 rpm, and react to the target particle size.

[0029] Secondly, the present invention provides an ultra-high nickel ternary precursor, which is prepared by the preparation method described in the first aspect.

[0030] Thirdly, the present invention provides a cathode material, which is prepared by mixing and calcining an ultra-high nickel ternary precursor with a lithium source.

[0031] The ultra-high nickel ternary precursor is either the ultra-high nickel ternary precursor prepared by the preparation method described in the first aspect, or the ultra-high nickel ternary precursor described in the second aspect.

[0032] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The preparation method provided by this invention matches the particle growth process by repeatedly reducing the stirring speed during the co-precipitation process. This ensures the uniformity of the nucleation stage while avoiding the breakage and irregular growth of large particles during the growth stage. Compared with a constant stirring speed, the staged stirring speed control can significantly improve the morphology and electrochemical performance of the precursor. Moreover, the preparation method provided by this invention has the advantages of simple process, good reproducibility, and applicability to industrial production. Attached Figure Description

[0035] Figure 1 Here are scanning electron microscope images of the ultra-high nickel ternary precursor obtained in Example 1;

[0036] Figure 2 Here are scanning electron microscope images of the ultra-high nickel ternary precursor obtained in Example 2;

[0037] Figure 3 Here are scanning electron microscope images of the ultra-high nickel ternary precursor obtained in Example 3;

[0038] Figure 4 Here is a scanning electron microscope image of the ultra-high nickel ternary precursor obtained in Example 4;

[0039] Figure 5 Here is a scanning electron microscope image of the ultra-high nickel ternary precursor obtained in Example 5;

[0040] Figure 6 Here are scanning electron microscope images of the ultra-high nickel ternary precursor obtained in Example 6;

[0041] Figure 7 The graphs show the first charge-discharge curves of the cathode materials obtained in Examples 1 to 6 at a rate of 0.1C. The horizontal axis represents the specific capacity (mAh / g), and the vertical axis represents the voltage (V).

[0042] Figure 8 The graph shows the cycling curves of the cathode materials obtained in Examples 1 to 6 at a 1C rate. The horizontal axis represents the number of cycles, and the vertical axis represents the capacity retention rate (%).

[0043] Figure 9 The graphs show the rate performance of the cathode materials obtained in Examples 1 to 6 at different rates. The horizontal axis represents the rate and the vertical axis represents the discharge capacity (mAh / g). Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0045] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0046] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0047] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0048] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0049] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0050] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0051] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0052] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0053] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0054] Existing technologies still face the following challenges when applied to ultra-high nickel systems: (1) Existing methods have failed to systematically study the relationship between synthesis conditions (pH, ammonia concentration, temperature) and morphology control; (2) Existing methods do not provide flexible process routes that can simultaneously meet different performance requirements (high tap density or high rate performance); (3) When scaled up industrial-scale reactors, it is difficult to simultaneously achieve high sphericity, narrow particle size distribution, and high tap density. Therefore, developing a preparation method suitable for ultra-high nickel systems, capable of precisely controlling precursor morphology, and suitable for industrial production is of great practical significance.

[0055] An embodiment of the present invention provides a method for preparing an ultra-high nickel ternary precursor, the method comprising:

[0056] A nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into the bottom solution to carry out a co-precipitation reaction, thereby obtaining the ultra-high nickel ternary precursor Ni. x Co y Mn z (OH)2, where x+y+z=1, x≥0.9, 0.01≤y≤0.09, 0.01≤z≤0.09;

[0057] During the coprecipitation reaction, the stirring speed is gradually reduced as the particle size increases;

[0058] During the coprecipitation reaction, the stirring speed is reduced at least 7 times.

[0059] The preparation method provided by this invention matches the particle growth process by repeatedly reducing the stirring speed during the co-precipitation process. This ensures the uniformity of the nucleation stage while avoiding the breakage and irregular growth of large particles during the growth stage. Compared with a constant stirring speed, the staged stirring speed control can significantly improve the morphology and electrochemical performance of the precursor. Moreover, the preparation method provided by this invention has the advantages of simple process, good reproducibility, and applicability to industrial production.

[0060] In some embodiments, the temperature of the coprecipitation reaction is 40°C to 70°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0061] In some embodiments, the pH value of the coprecipitation reaction is 9.7 to 11.2, for example, it can be 9.7, 10, 10.2, 10.5, 10.6, 10.8, 11 or 11.2, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] In some embodiments, the concentration of the complexing agent during the coprecipitation reaction is 3 g / L to 6.5 g / L, for example, it can be 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L or 6.5 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0063] In some embodiments, the temperature of the base solution is 40°C to 70°C, the pH is 9.7 to 11.2, and the concentration of the complexing agent is 3 g / L to 6.5 g / L. The pH of the base solution is adjusted by the precipitant solution, and the concentration of the complexing agent in the base solution is adjusted by the complexing agent solution.

[0064] In some embodiments, the precipitant in the precipitant solution includes sodium hydroxide and / or potassium hydroxide.

[0065] In some embodiments, the complexing agent solution includes ammonia.

[0066] Ammonia water, as a complexing agent, can form stable complexes, regulate the release rate of metal ions, and promote uniform precipitation.

[0067] In some embodiments, the nickel-cobalt-manganese mixed salt solution includes nickel salt, cobalt salt, and manganese salt;

[0068] The nickel salt includes any one or a combination of at least two of nickel sulfate, nickel nitrate, or nickel chloride. Typical but non-limiting combinations include combinations of nickel sulfate and nickel nitrate, nickel sulfate and nickel chloride, nickel nitrate and nickel chloride, or combinations of nickel sulfate, nickel nitrate, and nickel chloride.

[0069] The cobalt salt includes any one or a combination of at least two of cobalt sulfate, cobalt nitrate, or cobalt chloride. Typical but non-limiting combinations include a combination of cobalt sulfate and cobalt nitrate, a combination of cobalt nitrate and cobalt chloride, a combination of cobalt sulfate and cobalt chloride, or a combination of cobalt sulfate, cobalt nitrate, and cobalt chloride.

[0070] The manganese salt includes any one or a combination of at least two of manganese sulfate, manganese nitrate, or manganese chloride. Typical but non-limiting combinations include combinations of manganese sulfate and manganese nitrate, manganese nitrate and manganese chloride, manganese sulfate and manganese chloride, or combinations of manganese sulfate, manganese nitrate, and manganese chloride.

[0071] In some embodiments, the total metal ion concentration in the nickel-cobalt-manganese mixed salt solution is 80 g / L to 120 g / L. Typical but non-limiting combinations include 80 g / L, 90 g / L, 100 g / L, 110 g / L, or 120 g / L, but are not limited to the listed values. Other unlisted values ​​within the range are also applicable. Too low a total metal ion concentration will reduce production efficiency, while too high a concentration will easily lead to excessively rapid nucleation and uneven particle size.

[0072] In some embodiments, the coprecipitation reaction method is a densification method, and the stirring speed is gradually reduced as the particle size increases, including: the initial densification stirring speed is 300 rpm to 350 rpm, and the stirring speed is gradually reduced as the particle size increases. When the median particle size D50 reaches 10 μm to 12 μm, the stirring speed is reduced to 150 rpm to 220 rpm, and the reaction is carried out to the target particle size.

[0073] The densification method of the present invention refers to a process in which nucleation and growth are carried out continuously in the same reactor. By reducing the stirring speed in stages, the shear force is gradually reduced during particle growth, ensuring rapid nucleation under high supersaturation in the early stage, while avoiding large particles from breaking or growing irregularly due to excessive stirring speed in the later stage.

[0074] In some embodiments, the coprecipitation reaction is a densification process, in which the stirring speed is gradually reduced as the particle size increases. This includes: an initial densification stirring speed of 300-350 rpm; reducing the stirring speed to 280-320 rpm when the median particle size D50 reaches 4.3-4.7 μm; reducing the stirring speed to 260-300 rpm when the median particle size D50 reaches 5.3-5.7 μm; and reducing the stirring speed to 250 rpm when the median particle size D50 reaches 6.3-6.7 μm. When the median particle size D50 reaches 7.3μm~7.7μm, reduce the stirring speed to 220rpm~250rpm; when the median particle size D50 reaches 8.3μm~8.7μm, reduce the stirring speed to 200rpm~240rpm; when the median particle size D50 reaches 9.3μm~9.7μm, reduce the stirring speed to 180rpm~220rpm; when the median particle size D50 reaches 9.9μm~10.1μm, reduce the stirring speed to 150rpm~200rpm, and react to the target particle size.

[0075] In some embodiments, the coprecipitation reaction method is a seed method, and the stirring speed is gradually reduced as the particle size increases, including: preparing seed crystals with a median particle size D50 of 3μm to 5μm under the condition of 350rpm to 400rpm, and then carrying out the growth process in the presence of seed crystals;

[0076] The growth process includes: the initial seed crystal stirring speed is 280 rpm to 320 rpm, and the stirring speed is gradually reduced as the particle size increases. When the median particle size D50 reaches 10 μm to 12 μm, the stirring speed is reduced to 100 rpm to 150 rpm, and the reaction is carried out to the target particle size.

[0077] In this invention, the seed crystal method is divided into two stages. In the first stage, seed crystals with uniform particle size are prepared at a high stirring speed to serve as the core for subsequent growth. In the second stage, a fresh metal salt solution is added in the presence of the seed crystals for growth. By reducing the stirring speed in stages, the particles are controlled to grow isotropically, which significantly improves the sphericity and uniformity of the final product.

[0078] In some embodiments, the coprecipitation reaction method is a seed method, and the stirring speed is gradually reduced as the particle size increases, including: preparing seed crystals with a median particle size D50 of 3μm to 5μm under the condition of 350rpm to 400rpm, and then carrying out the growth process in the presence of seed crystals;

[0079] The growth process includes: initially stirring the seed crystals at 280 rpm to 320 rpm; reducing the stirring speed to 260 rpm to 300 rpm when the median particle size D50 reaches 4.8 μm to 5.2 μm; further reducing the stirring speed to 240 rpm to 270 rpm when the median particle size D50 reaches 6.3 μm to 6.7 μm; and finally reducing the stirring speed to 200 rpm to 240 rpm when the median particle size D50 reaches 7.3 μm to 7.7 μm. When the median particle size (D50) reaches 7.8 μm to 8.2 μm, reduce the stirring speed to 180 rpm to 200 rpm. When the median particle size (D50) reaches 8.8 μm to 9.2 μm, reduce the stirring speed to 150 rpm to 180 rpm. When the median particle size (D50) reaches 9.3 μm to 9.6 μm, reduce the stirring speed to 120 rpm to 150 rpm. When the median particle size (D50) reaches 9.8 μm to 10.2 μm, reduce the stirring speed to 100 rpm to 120 rpm, and react to the target particle size.

[0080] In some embodiments, the preparation method further includes washing and drying after the coprecipitation reaction.

[0081] For example, washing includes washing with deionized water until the conductivity of the filtrate is less than 100 μS / cm.

[0082] For example, the drying temperature can be 60℃~100℃ (e.g., 60℃, 70℃, 80℃, 90℃, or 100℃), and the drying time can be 8h~24h (e.g., 8h, 10h, 12h, 15h, 16h, 18h, 20h, 21h, 22h, or 24h). Too low a drying temperature will result in an excessively long drying time, while too high a temperature may cause precursor oxidation.

[0083] As one of the preferred technical solutions of the preparation method provided by the present invention, the preparation method includes:

[0084] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a base solution with a temperature of 40℃~70℃, a pH value of 9.7~11.2 and an ammonia concentration of 3g / L~6.5g / L;

[0085] S2. A mixed salt solution of nickel, cobalt, and manganese, along with sodium hydroxide and ammonia, are co-precipitated into the bottom solution to obtain the ultra-high nickel ternary precursor Ni. x Co y Mn z (OH)2, where x+y+z=1, x≥0.9, 0.01≤y≤0.09, 0.01≤z≤0.09;

[0086] The coprecipitation reaction was carried out at a temperature of 40℃ to 70℃, a pH value of 9.7 to 11.2, and an ammonia concentration of 3 g / L to 6.5 g / L.

[0087] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 80 g / L~120 g / L;

[0088] The coprecipitation reaction method is a densification method, comprising: an initial densification stirring speed of 300 rpm to 350 rpm; reducing the stirring speed to 280 rpm to 320 rpm when the median particle size D50 reaches 4.3 μm to 4.7 μm; reducing the stirring speed to 260 rpm to 300 rpm when the median particle size D50 reaches 5.3 μm to 5.7 μm; reducing the stirring speed to 250 rpm to 270 rpm when the median particle size D50 reaches 6.3 μm to 6.7 μm; and further reducing the stirring speed to 7.3 μm. When the median particle size (D50) reaches ~7.7 μm, reduce the stirring speed to 220 rpm to 250 rpm. When the median particle size (D50) reaches 8.3 μm to 8.7 μm, reduce the stirring speed to 200 rpm to 240 rpm. When the median particle size (D50) reaches 9.3 μm to 9.7 μm, reduce the stirring speed to 180 rpm to 220 rpm. When the median particle size (D50) reaches 9.9 μm to 10.1 μm, reduce the stirring speed to 150 rpm to 200 rpm. Continue the reaction until the median particle size (D50) reaches 10.8 μm to 11.2 μm.

[0089] As a second preferred embodiment of the preparation method provided by the present invention, the preparation method includes:

[0090] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a base solution with a temperature of 40℃~70℃, a pH value of 9.7~11.2 and an ammonia concentration of 3g / L~6.5g / L;

[0091] S2. A mixed salt solution of nickel, cobalt, and manganese, along with sodium hydroxide and ammonia, are co-precipitated into the bottom solution to obtain the ultra-high nickel ternary precursor Ni. x Co y Mn z (OH)2, where x+y+z=1, x≥0.9, 0.01≤y≤0.09, 0.01≤z≤0.09;

[0092] The coprecipitation reaction was carried out at a temperature of 40℃ to 70℃, a pH value of 9.7 to 11.2, and an ammonia concentration of 3 g / L to 6.5 g / L.

[0093] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 80 g / L~120 g / L;

[0094] The coprecipitation reaction method is a seed method, which includes: preparing seed crystals with a median particle size D50 of 3μm to 5μm under conditions of 350rpm to 400rpm, and then carrying out the growth process in the presence of the seed crystals;

[0095] The growth process includes: initially, the seed crystal stirring speed is 280 rpm to 320 rpm; when the median particle size D50 reaches 4.8 μm to 5.2 μm, the stirring speed is reduced to 260 rpm to 300 rpm; when the median particle size D50 reaches 6.3 μm to 6.7 μm, the stirring speed is reduced to 240 rpm to 270 rpm; when the median particle size D50 reaches 7.3 μm to 7.7 μm, the stirring speed is reduced to 200 rpm to 240 rpm; and when the median particle size D50 reaches 7.8 μm to 8.2 μm... When the median particle size D50 reaches 8.8μm~9.2μm, reduce the stirring speed to 180rpm~200rpm. When the median particle size D50 reaches 9.3μm~9.6μm, reduce the stirring speed to 120rpm~150rpm. When the median particle size D50 reaches 9.8μm~10.2μm, reduce the stirring speed to 100rpm~120rpm. Continue the reaction until the median particle size D50 reaches 10.8μm~11.2μm.

[0096] This invention provides an ultra-high nickel ternary precursor, which is prepared by the preparation method described in any of the embodiments.

[0097] This invention provides a cathode material, which is prepared by calcining an ultra-high nickel ternary precursor with a lithium source.

[0098] The ultra-high nickel ternary precursor is either the ultra-high nickel ternary precursor prepared by the preparation method described in any embodiment, or the ultra-high nickel ternary precursor described in any embodiment.

[0099] For example, a method for preparing a cathode material includes:

[0100] (1) The ultra-high nickel ternary precursor is mixed with a lithium source to obtain a mixture;

[0101] (2) The mixture is subjected to a first calcination and a second calcination in an oxygen-containing atmosphere to obtain the positive electrode material.

[0102] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1 to 1:1.1, for example, it can be 1:1, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.08, or 1:1.1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Too little lithium source will lead to lithium defects, affecting electrochemical performance; too much will result in residual lithium on the surface, increasing side reactions.

[0103] In some embodiments, the lithium source includes any one or a combination of at least two of lithium carbonate, lithium hydroxide, or lithium nitrate.

[0104] In some embodiments, the temperature of the first calcination can be 400°C to 600°C (e.g., 400°C, 450°C, 500°C, 550°C, or 600°C), and the time can be 3 hours to 6 hours (e.g., 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours). The first calcination is used to remove moisture and organic matter from the mixture and to allow the lithium source to initially melt and permeate.

[0105] In some embodiments, the temperature of the second calcination can be 700°C to 850°C (e.g., 700°C, 720°C, 750°C, 780°C, 800°C, 820°C, or 850°C, etc.), and the time can be 8h to 15h (8h, 9h, 10h, 11h, 12h, 14h, or 15h, etc.). The second calcination is used to form a complete layered structure.

[0106] Example 1

[0107] This embodiment provides a method for preparing a cathode material, including the following steps:

[0108] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a base solution with a temperature of 55℃, a pH value of 10.8 and an ammonia concentration of 5.5g / L.

[0109] S2. A nickel-cobalt-manganese mixed salt solution, 4 mol / L sodium hydroxide, and 2 mol / L ammonia solution are co-precipitated into the bottom solution. After aging for 2 hours, the solution is filtered, washed (with deionized water until the conductivity of the filtrate is <100 μS / cm), and dried (at 80°C for 12 hours) to obtain the ultra-high nickel ternary precursor Ni. 0.96 Co 0.02 Mn 0.02 (OH)2;

[0110] The coprecipitation reaction was carried out at a temperature of 55°C, a pH of 10.8, and an ammonia concentration of 5.5 g / L.

[0111] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 100 g / L;

[0112] The coprecipitation reaction method is a densification method, comprising: an initial densification stirring speed of 320 rpm, reducing the stirring speed to 300 rpm when the median particle size D50 reaches 4.5 μm, reducing the stirring speed to 280 rpm when the median particle size D50 reaches 5.5 μm, reducing the stirring speed to 260 rpm when the median particle size D50 reaches 6.5 μm, reducing the stirring speed to 240 rpm when the median particle size D50 reaches 7.5 μm, reducing the stirring speed to 220 rpm when the median particle size D50 reaches 8.5 μm, reducing the stirring speed to 200 rpm when the median particle size D50 reaches 9.5 μm, reducing the stirring speed to 180 rpm when the median particle size D50 reaches 10 μm, and reacting until the median particle size D50 reaches 11 ± 0.2 μm;

[0113] S3, an ultra-high nickel ternary precursor is mixed with a lithium source (lithium hydroxide) to obtain a mixture;

[0114] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1.05;

[0115] S4. The mixture is subjected to a first calcination and a second calcination in an oxygen atmosphere to obtain the positive electrode material; the temperature of the first calcination is 500°C and the time is 4 hours; the temperature of the second calcination is 790°C and the time is 10 hours.

[0116] The SEM image of the ultra-high nickel ternary precursor obtained in this embodiment is shown below. Figure 1 As shown, the ultra-high nickel ternary precursor particles obtained in this embodiment are spherical with a dense surface.

[0117] Example 2

[0118] This embodiment provides a method for preparing a cathode material, including the following steps:

[0119] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a base solution with a temperature of 40℃, a pH value of 9.7 and an ammonia concentration of 3g / L.

[0120] S2. A nickel-cobalt-manganese mixed salt solution, 4 mol / L sodium hydroxide, and 2 mol / L ammonia solution are co-precipitated into the bottom solution. After aging for 2 hours, the solution is filtered, washed (with deionized water until the conductivity of the filtrate is <100 μS / cm), and dried (at 60°C for 24 hours) to obtain the ultra-high nickel ternary precursor Ni. 0.96 Co 0.02 Mn 0.02 (OH)2;

[0121] The coprecipitation reaction was carried out at a temperature of 40°C, a pH of 9.7, and an ammonia concentration of 3 g / L.

[0122] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 80 g / L;

[0123] The coprecipitation reaction method is a densification method, comprising: an initial densification stirring speed of 300 rpm, reducing the stirring speed to 280 rpm when the median particle size D50 reaches 4.3 μm, reducing the stirring speed to 260 rpm when the median particle size D50 reaches 5.3 μm, reducing the stirring speed to 250 rpm when the median particle size D50 reaches 6.3 μm, reducing the stirring speed to 220 rpm when the median particle size D50 reaches 7.3 μm, reducing the stirring speed to 200 rpm when the median particle size D50 reaches 8.3 μm, reducing the stirring speed to 180 rpm when the median particle size D50 reaches 9.3 μm, reducing the stirring speed to 150 rpm when the median particle size D50 reaches 9.9 μm, and reacting until the median particle size D50 reaches 11 ± 0.2 μm;

[0124] S3, an ultra-high nickel ternary precursor is mixed with a lithium source (lithium hydroxide) to obtain a mixture;

[0125] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1.05;

[0126] S4. The mixture is subjected to a first calcination and a second calcination in an oxygen atmosphere to obtain the positive electrode material; the temperature of the first calcination is 500°C and the time is 4 hours; the temperature of the second calcination is 790°C and the time is 10 hours.

[0127] The SEM image of the ultra-high nickel ternary precursor obtained in this embodiment is shown below. Figure 2 As shown, the ultra-high nickel ternary precursor particles obtained in this embodiment are spherical with a dense surface.

[0128] Example 3

[0129] This embodiment provides a method for preparing a cathode material, including the following steps:

[0130] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a bottom solution with a temperature of 70℃, a pH value of 11.2 and an ammonia concentration of 6.5g / L;

[0131] S2. A nickel-cobalt-manganese mixed salt solution, 4 mol / L sodium hydroxide, and 2 mol / L ammonia solution are co-precipitated into the bottom solution. After aging for 2 hours, the solution is filtered, washed (with deionized water until the conductivity of the filtrate is <100 μS / cm), and dried (at 100°C for 8 hours) to obtain the ultra-high nickel ternary precursor Ni. 0.96 Co 0.02 Mn 0.02 (OH)2;

[0132] The coprecipitation reaction was carried out at a temperature of 70°C, a pH of 11.2, and an ammonia concentration of 6.5 g / L.

[0133] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 120 g / L;

[0134] The coprecipitation reaction method is a densification method, comprising: an initial densification stirring speed of 350 rpm, reducing the stirring speed to 320 rpm when the median particle size D50 reaches 4.7 μm, reducing the stirring speed to 300 rpm when the median particle size D50 reaches 5.7 μm, reducing the stirring speed to 270 rpm when the median particle size D50 reaches 6.7 μm, reducing the stirring speed to 250 rpm when the median particle size D50 reaches 7.7 μm, reducing the stirring speed to 240 rpm when the median particle size D50 reaches 8.7 μm, reducing the stirring speed to 220 rpm when the median particle size D50 reaches 9.7 μm, reducing the stirring speed to 200 rpm when the median particle size D50 reaches 10.1 μm, and reacting until the median particle size D50 reaches 11 ± 0.2 μm;

[0135] S3, an ultra-high nickel ternary precursor is mixed with a lithium source (lithium hydroxide) to obtain a mixture;

[0136] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1.05;

[0137] S4. The mixture is subjected to a first calcination and a second calcination in an oxygen atmosphere to obtain the positive electrode material; the temperature of the first calcination is 500°C and the time is 4 hours; the temperature of the second calcination is 790°C and the time is 10 hours.

[0138] The SEM image of the ultra-high nickel ternary precursor obtained in this embodiment is shown below. Figure 3 As shown, the ultra-high nickel ternary precursor particles obtained in this embodiment are spherical with a dense surface.

[0139] Example 4

[0140] This embodiment provides a method for preparing a cathode material, including the following steps:

[0141] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a base solution with a temperature of 55℃, a pH value of 10.8 and an ammonia concentration of 5.5g / L.

[0142] S2. A nickel-cobalt-manganese mixed salt solution, 4 mol / L sodium hydroxide, and 2 mol / L ammonia solution are co-precipitated into the bottom solution. After aging for 2 hours, the solution is filtered, washed (with deionized water until the conductivity of the filtrate is <100 μS / cm), and dried (at 80°C for 12 hours) to obtain the ultra-high nickel ternary precursor Ni. 0.96 Co 0.02 Mn 0.02 (OH)2;

[0143] The coprecipitation reaction was carried out at a temperature of 55°C, a pH of 10.8, and an ammonia concentration of 5.5 g / L.

[0144] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 100 g / L;

[0145] The coprecipitation reaction method is a seed method, which includes: preparing seed crystals with a median particle size D50 of 4 μm at 380 rpm, and then carrying out the growth process in the presence of the seed crystals;

[0146] The growth process includes: initially stirring the seed crystals at 300 rpm; reducing the stirring speed to 280 rpm when the median particle size D50 reaches 5 μm; reducing the stirring speed to 250 rpm when the median particle size D50 reaches 6.5 μm; reducing the stirring speed to 220 rpm when the median particle size D50 reaches 7.5 μm; reducing the stirring speed to 190 rpm when the median particle size D50 reaches 8 μm; reducing the stirring speed to 160 rpm when the median particle size D50 reaches 9 μm; reducing the stirring speed to 140 rpm when the median particle size D50 reaches 9.5 μm; reducing the stirring speed to 120 rpm when the median particle size D50 reaches 10 μm; and reacting until the median particle size D50 reaches 11 ± 0.2 μm.

[0147] S3, an ultra-high nickel ternary precursor is mixed with a lithium source (lithium hydroxide) to obtain a mixture;

[0148] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1.05;

[0149] S4. The mixture is subjected to a first calcination and a second calcination in an oxygen atmosphere to obtain the positive electrode material; the temperature of the first calcination is 500°C and the time is 4 hours; the temperature of the second calcination is 790°C and the time is 10 hours.

[0150] The SEM image of the ultra-high nickel ternary precursor obtained in this embodiment is shown below. Figure 4 As shown, the ultra-high nickel ternary precursor particles obtained in this embodiment are spherical with a dense surface.

[0151] Example 5

[0152] This embodiment provides a method for preparing a cathode material, including the following steps:

[0153] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a base solution with a temperature of 40℃, a pH value of 9.7 and an ammonia concentration of 3g / L.

[0154] S2. A nickel-cobalt-manganese mixed salt solution, 4 mol / L sodium hydroxide, and 2 mol / L ammonia solution are co-precipitated into the bottom solution. After aging for 2 hours, the solution is filtered, washed (with deionized water until the conductivity of the filtrate is <100 μS / cm), and dried (at 60°C for 24 hours) to obtain the ultra-high nickel ternary precursor Ni. 0.96 Co 0.02 Mn 0.02 (OH)2;

[0155] The coprecipitation reaction was carried out at a temperature of 40°C, a pH of 9.7, and an ammonia concentration of 3 g / L.

[0156] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 80 g / L;

[0157] The coprecipitation reaction method is a seed method, which includes: preparing seed crystals with a median particle size D50 of 3 μm at 350 rpm, and then carrying out the growth process in the presence of the seed crystals;

[0158] The growth process includes: initially stirring the seed crystals at 280 rpm; reducing the stirring speed to 260 rpm when the median particle size D50 reaches 4.8 μm; reducing the stirring speed to 240 rpm when the median particle size D50 reaches 6.3 μm; reducing the stirring speed to 200 rpm when the median particle size D50 reaches 7.3 μm; reducing the stirring speed to 180 rpm when the median particle size D50 reaches 7.8 μm; reducing the stirring speed to 150 rpm when the median particle size D50 reaches 8.8 μm; reducing the stirring speed to 120 rpm when the median particle size D50 reaches 9.3 μm; reducing the stirring speed to 100 rpm when the median particle size D50 reaches 9.8 μm; and reacting until the median particle size D50 reaches 11 ± 0.2 μm.

[0159] S3, an ultra-high nickel ternary precursor is mixed with a lithium source (lithium hydroxide) to obtain a mixture;

[0160] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1.05;

[0161] S4. The mixture is subjected to a first calcination and a second calcination in an oxygen atmosphere to obtain the positive electrode material; the temperature of the first calcination is 500°C and the time is 4 hours; the temperature of the second calcination is 790°C and the time is 10 hours.

[0162] The SEM image of the ultra-high nickel ternary precursor obtained in this embodiment is shown below. Figure 5 As shown, the ultra-high nickel ternary precursor particles obtained in this embodiment are spherical with a dense surface.

[0163] Example 6

[0164] This embodiment provides a method for preparing a cathode material, including the following steps:

[0165] S1. Mix deionized water, sodium hydroxide solution and ammonia water to obtain a bottom solution with a temperature of 70℃, a pH value of 11.2 and an ammonia concentration of 6.5g / L;

[0166] S2. A nickel-cobalt-manganese mixed salt solution, 4 mol / L sodium hydroxide, and 2 mol / L ammonia solution are co-precipitated into the bottom solution. After aging for 2 hours, the solution is filtered, washed (with deionized water until the conductivity of the filtrate is <100 μS / cm), and dried (at 100°C for 8 hours) to obtain the ultra-high nickel ternary precursor Ni. 0.96 Co 0.02 Mn 0.02 (OH)2;

[0167] The coprecipitation reaction was carried out at a temperature of 70°C, a pH of 11.2, and an ammonia concentration of 6.5 g / L.

[0168] The nickel-cobalt-manganese mixed salt solution is a mixed salt solution of nickel sulfate, manganese sulfate and cobalt sulfate, wherein the total metal ion concentration is 120 g / L;

[0169] The coprecipitation reaction method is a seed method, which includes: preparing seed crystals with a median particle size D50 of 5 μm at 400 rpm, and then carrying out the growth process in the presence of the seed crystals;

[0170] The growth process includes: initially stirring the seed crystals at 320 rpm; reducing the stirring speed to 300 rpm when the median particle size D50 reaches 5.2 μm; reducing the stirring speed to 270 rpm when the median particle size D50 reaches 6.7 μm; reducing the stirring speed to 240 rpm when the median particle size D50 reaches 7.7 μm; reducing the stirring speed to 200 rpm when the median particle size D50 reaches 8.2 μm; reducing the stirring speed to 180 rpm when the median particle size D50 reaches 9.2 μm; reducing the stirring speed to 150 rpm when the median particle size D50 reaches 9.6 μm; reducing the stirring speed to 120 rpm when the median particle size D50 reaches 10.2 μm; and reacting until the median particle size D50 reaches 11 ± 0.2 μm.

[0171] S3, an ultra-high nickel ternary precursor is mixed with a lithium source (lithium hydroxide) to obtain a mixture;

[0172] The molar ratio of the ultra-high nickel ternary precursor to lithium in the lithium source is 1:1.05;

[0173] S4. The mixture is subjected to a first calcination and a second calcination in an oxygen atmosphere to obtain the positive electrode material; the temperature of the first calcination is 500°C and the time is 4 hours; the temperature of the second calcination is 790°C and the time is 10 hours.

[0174] The SEM image of the ultra-high nickel ternary precursor obtained in this embodiment is shown below. Figure 6 As shown, the ultra-high nickel ternary precursor particles obtained in this embodiment are spherical with a dense surface.

[0175] Comparative Example 1

[0176] This comparative example provides a method for preparing a cathode material. Except for the coprecipitation reaction steps, which are different from those in Example 1, the rest are the same as in Example 1.

[0177] The coprecipitation reaction in this comparative example was carried out by a densification method, which included: an initial densification stirring speed of 320 rpm, reducing the stirring speed to 260 rpm when the median particle size D50 reached 6.5 μm, reducing the stirring speed to 220 rpm when the median particle size D50 reached 8.5 μm, reducing the stirring speed to 180 rpm when the median particle size D50 reached 10 μm, and reacting until the median particle size D50 reached 11 ± 0.2 μm.

[0178] Comparative Example 2

[0179] This comparative example provides a method for preparing a cathode material. Except for the coprecipitation reaction steps, which are different from those in Example 1, the rest are the same as in Example 1.

[0180] The coprecipitation reaction in this comparative example was carried out by a densification method, which included reacting at a constant stirring speed of 320 rpm until the median particle size D50 reached 11 ± 0.2 μm.

[0181] Comparative Example 3

[0182] This comparative example provides a method for preparing a cathode material. Except for the coprecipitation reaction steps, which are different from those in Example 4, the rest are the same as in Example 1.

[0183] The coprecipitation reaction method in this comparative example is the seed method, which includes: preparing seed crystals with a median particle size D50 of 4 μm at 380 rpm, and then carrying out the growth process in the presence of the seed crystals;

[0184] The growth process includes: the initial seed crystal stirring speed is 300 rpm, the stirring speed is reduced to 190 rpm when the median particle size D50 reaches 8 μm, the stirring speed is reduced to 140 rpm when the median particle size D50 reaches 9.5 μm, the stirring speed is reduced to 120 rpm when the median particle size D50 reaches 10 μm, and the reaction continues until the median particle size D50 reaches 11 ± 0.2 μm.

[0185] Comparative Example 4

[0186] This comparative example provides a method for preparing a cathode material. Except for the coprecipitation reaction steps, which are different from those in Example 4, the rest are the same as in Example 1.

[0187] The coprecipitation reaction method in this comparative example is the seed method, which includes: preparing seed crystals with a median particle size D50 of 4 μm at 380 rpm, and then carrying out the growth process in the presence of the seed crystals;

[0188] The growth process includes reacting at a constant stirring speed of 300 rpm until the median particle size D50 reaches 11 ± 0.2 μm.

[0189] Performance Characterization

[0190] The specific surface area (BET), tap density, and loose packing density of the ultra-high nickel ternary precursors obtained in the above embodiments and comparative examples were measured, and the results are shown in Table 1.

[0191] Table 1

[0192]

[0193] As shown in Examples 1-3 of Table 1, the dense ultra-high nickel ternary precursor prepared using the gradient decreasing stirring process of the present invention can achieve precise control over the specific surface area, tap density, and loose packing density of the precursor by adjusting the stirring speed gradient parameter. As shown in Examples 4-6, the gradient decreasing stirring process of the present invention is also applicable to the preparation of seed-method ultra-high nickel ternary precursors, enabling precise control over the physical properties of the precursor, and the overall specific surface area is higher than that of the dense method precursor, which conforms to the process characteristics of preparing high specific surface area precursors using the seed method.

[0194] When the number of times the gradient decreases the stirring speed is too small (Comparative Example 1), the stirring time in the nucleation stage is insufficient, resulting in a decrease in particle uniformity. In the growth stage, the stirring speed is too high, causing some particles to break. Finally, the tapped density is lower than that in Example 1. When a constant stirring speed is used (Comparative Example 2), it is impossible to simultaneously achieve uniform dispersion in the nucleation stage and particle densification in the growth stage. The particle morphology is irregular and there is a large amount of fine powder, further reducing the tapped density.

[0195] When the number of times the gradient stirring speed is reduced is too small (Comparative Example 3), the stirring speed is not properly matched during the seed growth process, resulting in uneven particle growth and a lower tap density compared to Example 4. When a constant stirring speed is used (Comparative Example 4), the seed crystals are prone to agglomeration and breakage, resulting in poor particle sphericity and a further reduction in tap density.

[0196] The obtained positive electrode material was mixed with conductive agent Super P and binder PVDF at a mass ratio of 90:5:5, and N-methylpyrrolidone was added to form a slurry. This slurry was then uniformly coated onto aluminum foil and vacuum dried at 110℃ for 12 hours. The resulting positive electrode was then rolled and punched to obtain the positive electrode sheet. Using lithium metal sheets as the negative electrode, a 1 mol / L LiPF6 EC / DEC / EMC solution (volume ratio 1:1:1) as the electrolyte, and Celgard 2400 as the separator, CR2032 coin cells were assembled in a glove box. Electrochemical tests were conducted within a voltage range of 2.8V to 4.3V, and the results are shown in Tables 2 and 3.

[0197] Electrochemical tests include: initial discharge specific capacity at 0.1C, capacity retention at 1C, and rate performance. Specifically, this includes testing at 0.1C rate (1C = 200 mA / g). -1 Three charge-discharge cycles were performed within a voltage range of 2.8V to 4.3V. The discharge specific capacity of the third cycle was recorded as the initial discharge specific capacity at 0.1C. After activation, continuous charge-discharge cycle tests were performed at a 1C rate within the same voltage range. The charge-discharge specific capacity of each cycle was recorded, and the capacity retention rate after 50 cycles was calculated (based on the 1C discharge specific capacity of the first cycle). Four charge-discharge cycles were performed at current densities of 0.2C, 0.5C, 1C, and 5C, respectively, and the discharge specific capacity of the fifth cycle at each rate was recorded. The initial charge-discharge curves of the cathode materials obtained in Examples 1 to 6 at a 0.1C rate are shown in the figure below. Figure 7 As shown, the cycling curves of the cathode materials obtained in Examples 1 to 6 at a 1C rate are as follows. Figure 8 As shown, the rate performance curves of the cathode materials obtained in Examples 1 to 6 at different rates are as follows. Figure 9 As shown.

[0198] Table 2

[0199]

[0200] As shown in Examples 1-3 of Table 2, the dense cathode material prepared using the gradient decreasing stirring process of the present invention can achieve balanced optimization of electrochemical performance by controlling the physical properties of the precursor. As shown in Examples 4-6, the seed-method cathode material prepared using the gradient decreasing stirring process of the present invention also exhibits excellent electrochemical performance, showing the same performance variation pattern as the dense method material, and its overall discharge specific capacity is higher than that of the dense method material. This is closely related to the higher specific surface area of ​​the seed-method precursor.

[0201] A comparison of Comparative Examples 1 and 2 with Example 1 shows that only by employing the process of repeatedly decreasing the stirring speed in this invention can the initial discharge specific capacity and cycle stability of the cathode material be improved simultaneously. When the number of times the stirring speed is decreased is too small (Comparative Example 1), the precursor particles have poor uniformity, resulting in a decrease in the initial discharge specific capacity and cycle capacity retention of the cathode material. When a constant stirring speed is used (Comparative Example 2), the precursor particles have irregular morphology and contain a large amount of fine powder, leading to further deterioration of the electrochemical performance of the cathode material.

[0202] Comparison of Comparative Examples 3 and 4 with Example 4 shows that when the number of times the gradient-reduced stirring speed is too small (Comparative Example 3), the uneven growth of the seed crystals leads to a decrease in the first discharge specific capacity and cycle capacity retention rate of the cathode material; when a constant stirring speed is used (Comparative Example 4), the problems of seed crystal agglomeration and breakage are serious, and the first discharge specific capacity and cycle capacity retention rate of the cathode material decrease.

[0203] Table 3

[0204]

[0205] As shown in Examples 1-3 of Table 3, the dense cathode material prepared using the gradient decreasing stirring process of the present invention exhibits excellent rate performance. As shown in Examples 4-6, the seed-method cathode material prepared using the gradient decreasing stirring process of the present invention exhibits even better rate performance.

[0206] Comparison of Comparative Examples 1 and 2 with Example 1 shows that when the number of times the gradient decreases the stirring speed is too small (Comparative Example 1), the uniformity of the precursor particles is poor, resulting in a decrease in the discharge specific capacity of the cathode material at a 5C rate; when a constant stirring speed is used (Comparative Example 2), the precursor particles have irregular morphology and contain a large amount of fine powder, which further deteriorates the rate performance of the cathode material.

[0207] Comparison of Comparative Examples 3 and 4 with Example 4 shows that when the number of times the gradient-reduced stirring speed is too small (Comparative Example 3), the uneven growth of the seed crystals leads to a decrease in the discharge specific capacity of the cathode material at a 5C rate; when a constant stirring speed is used (Comparative Example 4), the problems of seed crystal agglomeration and breakage are serious, and the discharge specific capacity of the cathode material at a 5C rate decreases.

[0208] In summary, the preparation method provided by this invention, by repeatedly reducing the stirring speed during the co-precipitation process to match the particle growth process, ensures the uniformity of the nucleation stage while avoiding the breakage and irregular growth of large particles during the growth stage. Compared with a constant stirring speed, the staged stirring speed control can significantly improve the morphology and electrochemical performance of the precursor. Moreover, the preparation method provided by this invention has the advantages of simple process, good reproducibility, and applicability to industrial production.

[0209] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing an ultra-high nickel ternary precursor, characterized in that, The preparation method includes: A nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into the bottom solution to carry out a co-precipitation reaction, thereby obtaining the ultra-high nickel ternary precursor Ni. x Co y Mn z (OH)2, where x+y+z=1, x≥0.9, 0.01≤y≤0.09, 0.01≤z≤0.09; During the coprecipitation reaction, the stirring speed is gradually reduced as the particle size increases; During the coprecipitation reaction, the stirring speed is reduced at least 7 times.

2. The preparation method according to claim 1, characterized in that, The temperature for the coprecipitation reaction is 40℃~70℃; And / or, the pH value of the coprecipitation reaction is 9.7~11.2; And / or, the concentration of the complexing agent during the coprecipitation reaction is 3 g / L to 6.5 g / L.

3. The preparation method according to claim 1 or 2, characterized in that, The precipitant in the precipitant solution includes sodium hydroxide and / or potassium hydroxide; And / or, the complexing agent solution includes ammonia.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The nickel-cobalt-manganese mixed salt solution includes nickel salt, cobalt salt and manganese salt; The nickel salt includes any one or a combination of at least two of nickel sulfate, nickel nitrate, or nickel chloride; The cobalt salt includes any one or a combination of at least two of cobalt sulfate, cobalt nitrate, or cobalt chloride. The manganese salt includes any one or a combination of at least two of manganese sulfate, manganese nitrate, or manganese chloride. And / or, the total metal ion concentration in the nickel-cobalt-manganese mixed salt solution is 80 g / L to 120 g / L.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The coprecipitation reaction method is a densification method, in which the stirring speed is gradually reduced as the particle size increases. The initial densification stirring speed is 300 rpm to 350 rpm, and the stirring speed is gradually reduced as the particle size increases. When the median particle size D50 reaches 10 μm to 12 μm, the stirring speed is reduced to 150 rpm to 220 rpm, and the reaction is carried out to the target particle size.

6. The preparation method according to claim 5, characterized in that, The coprecipitation reaction is performed using a densification method, with the stirring speed gradually decreasing as the particle size increases. This includes: an initial densification stirring speed of 300-350 rpm; reducing the stirring speed to 280-320 rpm when the median particle size D50 reaches 4.3-4.7 μm; reducing the stirring speed to 260-300 rpm when the median particle size D50 reaches 5.3-5.7 μm; and reducing the stirring speed to 250-270 rpm when the median particle size D50 reaches 6.3-6.7 μm. When the median particle size D50 reaches 7.3μm~7.7μm, reduce the stirring speed to 220rpm~250rpm; when the median particle size D50 reaches 8.3μm~8.7μm, reduce the stirring speed to 200rpm~240rpm; when the median particle size D50 reaches 9.3μm~9.7μm, reduce the stirring speed to 180rpm~220rpm; when the median particle size D50 reaches 9.9μm~10.1μm, reduce the stirring speed to 150rpm~200rpm, and react to the target particle size.

7. The preparation method according to any one of claims 1 to 4, characterized in that, The coprecipitation reaction method is the seed method, which involves gradually reducing the stirring speed as the particle size increases. This includes preparing seed crystals with a median particle size D50 of 3μm to 5μm at 350rpm to 400rpm, and then carrying out the growth process in the presence of the seed crystals. The growth process includes: the initial seed crystal stirring speed is 280 rpm to 320 rpm, and the stirring speed is gradually reduced as the particle size increases. When the median particle size D50 reaches 10 μm to 12 μm, the stirring speed is reduced to 100 rpm to 150 rpm, and the reaction is carried out to the target particle size.

8. The preparation method according to claim 7, characterized in that, The coprecipitation reaction method is the seed method, which involves gradually reducing the stirring speed as the particle size increases. This includes preparing seed crystals with a median particle size D50 of 3μm to 5μm at 350rpm to 400rpm, and then carrying out the growth process in the presence of the seed crystals. The growth process includes: initially stirring the seed crystals at 280 rpm to 320 rpm; reducing the stirring speed to 260 rpm to 300 rpm when the median particle size D50 reaches 4.8 μm to 5.2 μm; further reducing the stirring speed to 240 rpm to 270 rpm when the median particle size D50 reaches 6.3 μm to 6.7 μm; and finally reducing the stirring speed to 200 rpm to 240 rpm when the median particle size D50 reaches 7.3 μm to 7.7 μm. When the median particle size (D50) reaches 7.8 μm to 8.2 μm, reduce the stirring speed to 180 rpm to 200 rpm. When the median particle size (D50) reaches 8.8 μm to 9.2 μm, reduce the stirring speed to 150 rpm to 180 rpm. When the median particle size (D50) reaches 9.3 μm to 9.6 μm, reduce the stirring speed to 120 rpm to 150 rpm. When the median particle size (D50) reaches 9.8 μm to 10.2 μm, reduce the stirring speed to 100 rpm to 120 rpm, and react to the target particle size.

9. A high-nickel ternary precursor, characterized in that, The ultra-high nickel ternary precursor is prepared by the preparation method described in any one of claims 1 to 8.

10. A positive electrode material, characterized in that, The cathode material is prepared by calcining an ultra-high nickel ternary precursor with a lithium source. The ultra-high nickel ternary precursor is the ultra-high nickel ternary precursor prepared by the preparation method according to any one of claims 1 to 8, or the ultra-high nickel ternary precursor according to claim 9.

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