Cathode material precursor, preparation method thereof, cathode material, lithium ion battery and lithium electric device

Abstract

The application provides a positive electrode material precursor, a preparation method of the positive electrode material precursor, a positive electrode material, a lithium ion battery and a lithium battery device. The positive electrode material precursor comprises a plurality of secondary particles, the plurality of secondary particles comprise first particles and second particles, and the particle size of the first particles is smaller than the particle size of the second particles. The number proportion of the first particles is greater than the number proportion of the second particles, and the volume proportion of the first particles is less than the volume proportion of the second particles. The positive electrode material precursor provided in the application has the characteristics of a large volume proportion of large particles and a large number proportion of small particles, can balance the specific capacity and the cycle performance, and has a better application prospect.

Description

Technical Field

[0001] This application relates to the field of cathode material technology, and in particular to a cathode material precursor and its preparation method, cathode materials, lithium-ion batteries, and lithium-ion devices. Background Technology

[0002] With the continuous development of the new energy industry, lithium-ion batteries, as a new type of green battery, have received widespread attention and research. Cathode materials, as a crucial component of lithium-ion batteries, directly affect their capacity, cycle life, and safety performance. Among them, ternary cathode materials, as commonly used cathode materials for lithium-ion batteries, have always been at the core of the technology. To ensure battery performance, ternary cathode material precursors and cathode material products on the market are gradually developing towards higher nickel content and more stable structures.

[0003] As the nickel content increases, the specific capacity of ternary cathode materials gradually increases, but their cycle performance and safety performance deteriorate accordingly. Summary of the Invention

[0004] This application aims to at least improve one of the technical problems existing in the prior art. To this end, this application provides a cathode material precursor and its preparation method, a cathode material, a lithium-ion battery, and a lithium battery device.

[0005] This application provides a cathode material precursor, comprising a plurality of secondary particles, the plurality of secondary particles including a first type of particles and a second type of particles, wherein the particle size of the first type of particles is smaller than the particle size of the second type of particles;

[0006] Among them, the proportion of the first type of particles is greater than the proportion of the second type of particles, and the proportion of the volume of the first type of particles is less than the proportion of the volume of the second type of particles.

[0007] The cathode material precursor provided in this application exhibits a bimodal particle size distribution in particle size distribution testing, comprising a first type of particle and a second type of particle with different particle sizes. The particle size of the first type of particle is smaller than that of the second type of particle. Figure 4 As shown, the first type of particles is the collection of particles with the first peak, and the second type of particles is the collection of particles with the second peak. The particle size boundary between the first and second peaks can be any value among 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, and 3.0 μm.

[0008] Since the proportion of smaller first-type particles is greater than that of larger second-type particles, meaning there are more small particles, the contact area between the cathode material and the electrolyte can be increased, which is beneficial for improving specific capacity. Furthermore, the volume proportion of larger second-type particles is greater than that of smaller first-type particles, meaning the larger particles have a larger volume, which is beneficial for appropriately improving cycle performance. Therefore, the cathode material precursor provided in this application embodiment can balance specific capacity and cycle performance.

[0009] In some embodiments of this application, the cathode material precursor has a particle size of ≤2μm for the first type of particles and a particle size of >2μm for the second type of particles.

[0010] In some embodiments of this application, the cathode material precursor has a quantity ratio of ≥60% for the first type of particles and a volume ratio of ≥60% for the second type of particles;

[0011] Optionally, the first type of particles accounts for 91%-99% of the total.

[0012] Optionally, the proportion of the second type of particles is 1%-9%;

[0013] Optionally, the second type of particles further includes type A particles and type B particles, wherein the particle size of type A particles is >2μm and <10μm; and the particle size of type B particles is ≥10μm.

[0014] Optionally, the proportion of Class A particles is 1%-8.99%;

[0015] Optionally, the proportion of type B particles is 0.01%-0.1%.

[0016] In some embodiments of this application, the cathode material precursor satisfies at least one of the following conditions:

[0017] a. The particle size distribution span value of the secondary particles is 0.70-1.60;

[0018] b. The average particle size D50 of the secondary particles is 8.4-11.0 μm;

[0019] c. The specific surface area of ​​the secondary particles is 8-15 m². 2 / g;

[0020] d. The tap density of the secondary particles is 1.8-2.1 g / cm³. 3 ;

[0021] e. The peak intensity ratio I between the characteristic peak of the (101) crystal plane and the characteristic peak of the (001) crystal plane of the secondary particle. 101 / I001 It is 1.0-1.2;

[0022] f. The cathode material precursor satisfies the following relationship:

[0023] y = -Ax 2 +Bx-C

[0024] Where x is the average particle size D50 / μm of the secondary particles, and y is the percentage of the first type of particles.

[0025] A is selected from 0.08-0.09, B is selected from 1.7-1.9, and C is selected from 8-9;

[0026] g. The secondary particles are spherical or near-spherical in shape;

[0027] h. The secondary particle is composed of multiple primary particles, and the primary particles are spindle-shaped or sheet-shaped.

[0028] i. The secondary particle is composed of multiple primary particles, and the length-to-thickness ratio of the primary particle is 3-10, optionally 6-7;

[0029] j. The secondary particle is composed of multiple primary particles, and the thickness of the primary particle is 1.0-10.0 nm, optionally 2.0-8.0 nm.

[0030] In some embodiments of this application, the general chemical formula of the cathode material precursor is Ni. x Co y Mn z M a (OH)2, wherein 0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B and Zn, and 0≤a≤0.05; optionally, 0.8≤x<1, 0≤y≤0.2, 0≤z≤0.2, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B and Zn, and 0≤a≤0.05; optionally, the cathode material precursor is a layered hydroxide.

[0031] Another embodiment of this application provides a method for preparing a cathode material precursor, including the following steps:

[0032] A first base solution is prepared by mixing a precipitant and a complexing agent, and then a precipitant, a complexing agent, and a metal salt solution are added to the first base solution to carry out a first reaction to obtain seed crystals.

[0033] The seed crystals are mixed with a precipitant and a complexing agent to prepare a second base solution. The precipitant, complexing agent, metal salt solution, and the seed crystals are then added to the second base solution to carry out a second reaction to obtain the reaction product.

[0034] The reaction products were post-processed to obtain the cathode material precursor.

[0035] In some embodiments of this application, the preparation method satisfies at least one of the following conditions (1)-(10):

[0036] (1) The metal salt includes soluble salts of nickel, cobalt and / or manganese;

[0037] Optionally, the soluble salt includes at least one of nitrates, chlorides, and sulfates;

[0038] Optionally, the total concentration of metal ions in the metal salt solution is 1.0-2.0 mol / L;

[0039] (2) During the first reaction and the second reaction, the flow rate of the added metal salt solution is 4.0%-7.5% of the available volume of the reaction vessel;

[0040] (3) The complexing agent includes ammonia water, and the ammonia concentration in the first reaction process is 3.5-4.5 g / L;

[0041] (4) The ammonia concentration in the second reaction process is 4.5-5.5 g / L;

[0042] (5) The pH value of the first base solution is 11.50-12.00;

[0043] (6) The pH value of the reaction system for the first reaction is 11.65-11.95;

[0044] (7) The pH value of the second substrate is 10.40-10.90;

[0045] (8) The pH value of the reaction system for the second reaction is 10.3-10.7;

[0046] (9) The reaction temperature of the first reaction and the second reaction is 50-80℃;

[0047] (10) Both the first reaction and the second reaction are carried out under stirring, and the stirring speed is 100-200 r / min.

[0048] Another embodiment of this application provides a cathode material prepared from the cathode material precursor described above.

[0049] Another embodiment of this application provides a lithium-ion battery prepared from the above-described positive electrode material.

[0050] Another embodiment of this application provides a lithium battery device prepared from the lithium-ion battery described above.

[0051] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0052] To more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a SEM image of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 1 of this application;

[0054] Figure 2 This is a high-magnification electron microscope image of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 1 of this application;

[0055] Figure 3 A CP cross-sectional view of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 1 of this application;

[0056] Figure 4 This is a particle size distribution diagram of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 1 of this application;

[0057] Figure 5 This is a particle size distribution diagram of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 1 of this application;

[0058] Figure 6 This is a SEM image of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 2 of this application;

[0059] Figure 7 This is a high-magnification electron microscope image of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 2 of this application;

[0060] Figure 8 A cross-sectional view of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 2 of this application;

[0061] Figure 9 This is a SEM image of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 3 of this application;

[0062] Figure 10 This is a high-magnification electron microscope image of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 3 of this application;

[0063] Figure 11 A CP cross-sectional view of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 3 of this application;

[0064] Figure 12 This is a SEM image of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 4 of this application;

[0065] Figure 13 This is a high-magnification electron microscope image of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 4 of this application;

[0066] Figure 14 A cross-sectional view of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Example 4 of this application;

[0067] Figure 15 This is a SEM image of the nickel-cobalt-manganese ternary cathode material precursor prepared in Comparative Example 1 of this application;

[0068] Figure 16 High-magnification electron microscope image of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Comparative Example 1 of this application;

[0069] Figure 17 This is a CP cross-sectional view of the second type of particles of the nickel-cobalt-manganese ternary cathode material precursor prepared in Comparative Example 1 of this application. Detailed Implementation

[0070] The "range" disclosed in this application is defined by 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 a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, 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 a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" 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 "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0071] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0072] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0073] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may 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.

[0074] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0075] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0076] In this application, the quantity percentage refers to the proportion of a certain type of particle to the total number of all types of particles. For example, when the secondary particles of the cathode material precursor include first-type particles and second-type particles, the quantity percentage of the first-type particles refers to the proportion of the first-type particles to the total number of first-type particles and second-type particles.

[0077] Volume percentage refers to the proportion of the total volume of a certain type of particle to the total volume of all types of particles. For example, when the secondary particles of the cathode material precursor include type I particles and type II particles, the volume percentage of type I particles refers to the proportion of the total volume of type I particles to the total volume of type I particles and type II particles.

[0078] D50 refers to the particle size corresponding to a cumulative volume distribution percentage of secondary particles in the cathode material precursor that is 50% or more; D90 refers to the particle size corresponding to a cumulative volume distribution percentage of secondary particles in the cathode material precursor that is 90% or more; and D10 refers to the particle size corresponding to a cumulative volume distribution percentage of secondary particles in the cathode material precursor that is 10% or more.

[0079] Pure water generally refers to water with an electrical conductivity of less than or equal to 10 μS / cm, total organic carbon of less than or equal to 20 mg / L, metal ions (Na, K, Ca, Mg, etc.) of less than or equal to 1000 μg / L, and other ions (Cl, NO3-) of less than or equal to 1000 μg / L. - Water with a concentration of less than or equal to 2000 μg / L.

[0080] This application provides a cathode material precursor comprising multiple secondary particles, including first-type particles and second-type particles, wherein the particle size of the first-type particles is smaller than that of the second-type particles; wherein the proportion of first-type particles is greater than the proportion of second-type particles (e.g., ...). Figure 4 As shown), the volume percentage of the first type of particles is smaller than that of the second type of particles (e.g., ...). Figure 5 (As shown).

[0081] The cathode material precursor provided in this application exhibits a bimodal particle size distribution in particle size distribution testing, comprising a first type of particle and a second type of particle with different particle sizes. The particle size of the first type of particle is smaller than that of the second type of particle. Figure 4As shown, the first type of particles is the collection of particles with the first peak, and the second type of particles is the collection of particles with the second peak. The particle size boundary between the first and second peaks can be any value among 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, and 3.0 μm.

[0082] Since the proportion of smaller first-type particles is greater than that of larger second-type particles, meaning there are more small particles, the contact area between the cathode material and the electrolyte can be increased, which is beneficial for improving specific capacity. Furthermore, the volume proportion of larger second-type particles is greater than that of smaller first-type particles, meaning the larger particles have a larger volume, which is beneficial for appropriately improving cycle performance. Therefore, the cathode material precursor provided in this application embodiment can balance specific capacity and cycle performance.

[0083] In some embodiments, the particle size of the first type of particles is ≤2μm; the particle size of the second type of particles is >2μm. Optionally, the particle size of the second type of particles can be any one of 4μm, 8μm, 12μm, 16μm, 20μm and >2μm.

[0084] To fully enhance advantages such as specific capacity and cycle performance, the proportion of smaller first-class particles and the volume proportion of larger second-class particles can be controlled.

[0085] In some embodiments, the number proportion of the first type of particles is ≥60%, and the volume proportion of the second type of particles is ≥60%. Optionally, the number proportion of the first type of particles can be any one of 70%, 80%, 85%, 90%, 95%, and 60%-99%. Optionally, the volume proportion of the second type of particles can be any one of 70%, 80%, 85%, 90%, 95%, and 60%-99%. Within the above suitable numerical ranges, cathode materials with better specific capacity and cycle performance can be obtained, which is beneficial for improving the corresponding electrochemical performance when used in the preparation of lithium-ion batteries.

[0086] In some embodiments, the proportion of the first type of particles is 91%-99%, and the proportion of the second type of particles is 1%-9%. By reasonably controlling the proportion of the first type of particles and the second type of particles with different particle sizes, the contact between the cathode material and the electrolyte can be more sufficient, which is beneficial to further improve the specific capacity.

[0087] In some embodiments, the second type of particles further includes type A particles and type B particles, wherein the particle size of type A particles is >2 μm and <10 μm, and the particle size of type B particles is ≥10 μm. The cathode material precursor of this embodiment has first and second types of particles with different particle sizes. The second type of particles further includes type A and type B particles with different particle sizes, resulting in a more uniform particle size distribution and higher tap density, which is beneficial for further improving the energy density of the cathode material.

[0088] In some embodiments, the number of Class A particles accounts for 1%-8.99%.

[0089] In some embodiments, the number percentage of the type B particles is 0.01%-0.1%. Optionally, the volume percentage of the type B particles can be any one of 0.02%, 0.03%, 0.05%, 0.07%, 0.09%, and 0.01%-0.1%. This is advantageous for preparing cathode materials with good specific capacity, cycle performance, and energy density from cathode material precursors.

[0090] The quantity percentage was determined using a Mastersizer 3000 (Malvin 3000 laser particle size analyzer). (Refer to...) Figure 4 As shown in the figure, the particle size distribution of the cathode material precursor prepared in Example 1 is obtained by Mastersizer 3000. The proportion of the first type of particles, the second type of particles, the A type of particles and the B type of particles with different particle sizes can be calculated from the figure, as shown in Table 2 below.

[0091] In some embodiments, the span value of the secondary particle size distribution is 0.70-1.60, optionally 1.30-1.50, where the span value = (D90-D10) / D50. Under the wider particle size distribution range in this embodiment, the resulting cathode material precursor exhibits more uniform particle size distribution and higher tap density. After being fabricated into the corresponding cathode material, it has the advantage of higher compaction density, which is beneficial for improving the energy density of the cathode material.

[0092] It should be understood that in the prior art, the proportion of particles of different sizes in the cathode material precursor with a wide particle size distribution is unreasonable and uncontrollable, and the morphological consistency of particles of different sizes is poor. This leads to unstable physicochemical properties of the cathode material, such as tap density, specific surface area, and crystallinity, resulting in unsatisfactory discharge capacity and long-cycle performance. In the embodiments of this application, by reasonably controlling the proportion of particles of different sizes in the cathode material precursor, at least some of the defects of the prior art can be overcome. The resulting cathode material precursor with a wide particle size distribution has better performance, especially in balancing specific capacity and cycle performance, and has better application prospects.

[0093] In some embodiments, the cathode material precursor satisfies the following relationship:

[0094] y = -Ax 2 +Bx-C

[0095] Where x is the average particle size D50 / μm of secondary particles, and y is the percentage of the number of first-class particles.

[0096] A is selected from 0.08-0.09, B is selected from 1.7-1.9, and C is selected from 8-9.

[0097] Based on the above relationship, the proportion of smaller first-type particles can be determined according to the average particle size D50 of the secondary particles. Specifically, when preparing the cathode material precursor, the preparation process can be terminated by monitoring the average particle size D50 of the secondary particles. When the preparation process is terminated, the average particle size D50 of the secondary particles and the proportion of first-type particles satisfy the above relationship. Therefore, by controlling the particle size of the secondary particles, the proportion of first-type particles can be controlled, making the proportion of particles of different sizes controllable. This is beneficial for regulating the overall physicochemical properties of the obtained cathode material precursor, thereby improving the specific capacity and cycle performance of the cathode material.

[0098] In some embodiments, the secondary particles are composed of multiple primary particles, and the secondary particles are spherical or near-spherical. Spherical or near-spherical secondary particles can effectively improve the filling capacity of the active material in the positive electrode, which is beneficial to improving the energy density.

[0099] In some embodiments, the primary particles are spindle-shaped or sheet-like. (See reference...) Figure 2 As shown, the microstructure of the cathode material precursor prepared in Example 1 is illustrated. Primary particles are arranged in a disordered, spindle-shaped or sheet-like manner, and randomly interspersed to form secondary particles. This enhances the structural stability of the cathode material and improves cycle performance.

[0100] Furthermore, controlling the specific size of the primary particles within a suitable range is also beneficial for balancing specific capacity and cycle performance. In some embodiments, the length-to-thickness ratio of the primary particles is 3-10, optionally 6-7; the thickness of the primary particles is 1.0-10.0 nm, optionally 2-8 nm. Within the aforementioned suitable range of primary particle length-to-thickness ratio and thickness, the structural stability of the cathode material can be enhanced as much as possible while ensuring specific capacity, thereby effectively balancing specific capacity and cycle performance.

[0101] The method for testing the length and thickness of primary particles is as follows: Nano Measurer software is used to measure the length and thickness of primary particles on the surface of high-magnification secondary particles. The longest axis of a single primary particle is considered its length, and the short axis measured perpendicular to the midpoint of the longest axis is considered its thickness. The length / thickness ratio is then taken as the length-to-thickness ratio. In this application, five primary particles were randomly selected from the surface under a high-magnification electron microscope for measurement, and the obtained thickness and length-to-thickness ratio are both within the ranges in Table 2.

[0102] In some embodiments, the general chemical formula of the cathode material precursor is Ni. x Co y Mn z M a (OH)2, wherein 0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B and Zn, and 0≤a≤0.05; optionally, 0.8≤x<1, 0≤y≤0.2, 0≤z≤0.2, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B and Zn, and 0≤a≤0.05; optionally, the cathode material precursor is a layered hydroxide.

[0103] The cathode material precursor provided in this embodiment is a high-nickel product, and the corresponding cathode material has the advantages of good cycle performance, high energy density, good stability and safety performance.

[0104] In some embodiments, the average particle size D50 of the secondary particles is 8.4-11.0 μm. Within a suitable average particle size D50 range in this embodiment, it is beneficial to obtain a broadly distributed cathode material precursor with a high proportion of large particles in volume, a high proportion of small particles in number, and a controllable proportion of particles of different sizes. The corresponding cathode material exhibits high specific capacity while also possessing good cycle performance.

[0105] In some embodiments, the specific surface area of ​​the secondary particles is 8-15 m². 2 / g. By controlling the specific surface area within a suitable range, it is possible to prevent secondary particles from undergoing side reactions with the electrolyte.

[0106] In some embodiments, the tap density of the secondary particles is 1.8-2.1 g / cm³. 3 By controlling the tap density within a suitable range, it is beneficial to improve the energy density of the cathode material.

[0107] In some embodiments, in the X-ray diffraction pattern, the peak intensity ratio I of the characteristic peak of the (101) crystal plane of the secondary particle to the characteristic peak of the (001) crystal plane is... 101 / I 001 The peak intensity ratio is 1.0-1.2. In this embodiment, the peak intensity ratio I...101 / I 001 A larger value increases the overall crystallinity of the material and results in a higher proportion of small particles, leading to better high-temperature cycling performance of the cathode material.

[0108] The method for obtaining the CP cross-sectional image is as follows: First, the prepared precursor particles are vacuum-embedded on conductive adhesive, then the particles are cut, and finally, the cut precursor powder is photographed using a HITACHI SU8100 SEM image to obtain the final CP cross-sectional image.

[0109] Another embodiment of this application provides a method for preparing a cathode material precursor, comprising the following steps: mixing a precipitant and a complexing agent to prepare a first base solution, and continuing to add the precipitant, complexing agent, and metal salt solution to the first base solution to carry out a first reaction to obtain seed crystals; taking the seed crystals and mixing them with the precipitant and complexing agent to prepare a second base solution, and continuing to add the precipitant, complexing agent, metal salt solution, and seed crystals to the second base solution to carry out a second reaction to obtain a reaction product; and performing post-processing on the reaction product to obtain a cathode material precursor.

[0110] According to the preparation method provided in the embodiments of this application, the cathode material precursor is prepared by co-precipitation through the above specific steps and conditions. A wide-distribution cathode material precursor with a large proportion of large particles, a large proportion of small particles, and a controllable proportion of particles of different sizes can be obtained, which can improve the specific capacity of the corresponding battery and improve cycle life and stability.

[0111] In some embodiments, the metal salt includes soluble salts of nickel, cobalt, and / or manganese, such as at least one of nitrates, chlorides, and sulfates. Depending on the type of metal salt selected, a metal with the general chemical formula Ni can be prepared. x Co y Mn z M a The precursor for (OH)₂ cathode material has the following properties: 0.7 ≤ x < 1, 0 ≤ y ≤ 0.3, 0 ≤ z ≤ 0.3, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B, and Zn, and 0 ≤ a ≤ 0.05. For example, a nickel-cobalt-manganese ternary cathode material precursor can be prepared by using metal salts containing nickel, cobalt, and manganese.

[0112] In some embodiments, the total metal ion concentration of the metal salt solution is 1.0-2.0 mol / L, and during the first and second reactions, the flow rate of the metal salt solution is 4.0%-7.5% / h of the available volume of the reaction vessel, and the seed crystal addition rate during the second reaction is 8-10% / h of the available volume of the reaction vessel. By controlling the total metal ion concentration and flow rate of the metal salt solution within the above-mentioned suitable ranges, it is beneficial to prepare a cathode material precursor that meets the target requirements.

[0113] In some embodiments, the precipitant includes one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, and potassium carbonate solution; the concentration of the precipitant is 5-12 mol / L.

[0114] In some embodiments, the complexing agent includes one or more of ammonia, citric acid, sodium citrate, ammonium citrate, oxalic acid, ammonium oxalate, ammonium carbonate, malic acid, and lactic acid; the concentration of the complexing agent is 1-10 mol / L.

[0115] In some embodiments, the complexing agent includes ammonia water, the ammonia concentration in the first reaction process is 3.5-4.5 g / L, and the ammonia concentration in the second reaction process is 4.5-5.5 g / L. By adjusting the ammonia concentration in the first and second reaction processes respectively, a cathode material precursor with high specific capacity and good cycle performance can be obtained.

[0116] In some embodiments, the pH of the first substrate is 11.50-12.00; the pH of the reaction system for the first reaction is 11.65-11.95; the pH of the second substrate is 10.40-10.90; and the pH of the reaction system for the second reaction is 10.3-10.7. By adjusting the pH values ​​of the first and second substrates, as well as the first and second reaction processes, respectively, a cathode material precursor with high specific capacity and good cycle performance can be obtained.

[0117] In some embodiments, the reaction temperature of the first reaction and the second reaction is 50-80°C; this temperature is advantageous for preparing a broadly distributed cathode precursor with a controllable proportion of particles of different sizes.

[0118] In some embodiments, both the first and second reactions are carried out under stirring conditions, and the stirring speed is 100-200 r / min; this is beneficial for preparing a wide-distribution positive electrode precursor with a controllable proportion of particles of different sizes.

[0119] In some embodiments, the particle size distribution span of the cathode material precursor is 1.3-1.5. The resulting cathode precursor has a wider particle size distribution and higher tap density, which is beneficial for improving the energy density of the cathode material.

[0120] In some embodiments, the average particle size D50 of the seed crystals obtained in the first reaction is 2-4 μm. In this case, after obtaining the seed crystals through the first reaction, changing the reaction conditions to carry out the second reaction is beneficial to obtaining a broadly distributed cathode material precursor with a large proportion of large particles in volume, a large proportion of small particles in number, and a controllable proportion of particles of different sizes.

[0121] According to another embodiment of this application, a cathode material is provided, which is made using the above-described cathode material precursor. For example, the cathode material precursor in the above embodiment can be mixed with a lithium salt and then sintered to prepare the cathode material, which can be directly used to prepare a lithium-ion battery. Due to the use of the above-described cathode material precursor, the obtained cathode material has advantages such as high specific capacity, good cycle stability, and high energy density.

[0122] According to another embodiment of this application, a lithium-ion battery is provided, which is prepared using the above-described positive electrode material. For example, the positive electrode material in the above embodiments can be directly used to prepare a lithium-ion battery.

[0123] According to another embodiment of this application, a lithium battery device is provided, which is prepared using the lithium-ion battery described above. For example, the lithium-ion battery in the above embodiment can be directly used in the lithium battery device.

[0124] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all reagents and raw materials used in the embodiments are commercially available or synthesized by conventional methods, and the instruments used in the embodiments are also commercially available.

[0125] Example 1

[0126] This embodiment provides a method for preparing a nickel-cobalt-manganese ternary cathode material precursor, including the following steps:

[0127] (1) Raw material preparation:

[0128] Metal salt solution: Soluble salts of nickel, cobalt, and manganese were selected as raw materials, and a mixed nickel-cobalt-manganese solution with a concentration of 2.0 mol / L was prepared according to the molar ratio Ni:Co:Mn = 92:7:1.

[0129] Precipitating agent: Prepare a 10 mol / L sodium hydroxide aqueous solution as a precipitating agent;

[0130] Complexing agent: Prepare an ammonia solution with a concentration of 9 mol / L as a complexing agent.

[0131] (2) First reaction:

[0132] A certain amount of pure water, precipitant, and complexing agent were added to a reactor and stirred at 180 r / min under a constant temperature of 65℃ to obtain a first base liquid with a pH of 11.80. An inert gas was introduced into the first base liquid as a protective gas, and a circulating magnetic pump was used to uniformly add the nickel-cobalt-manganese mixed solution, complexing agent, and precipitant into the reactor containing the first base liquid. The first reaction was carried out using a continuous feeding and discharging method. During the first reaction, the flow rate of the nickel-cobalt-manganese mixed solution was 5.0% / h of the available volume of the reactor. The pH of the reaction system was controlled to be 11.75-11.95 and the ammonia concentration to be 4.5 g / L by fine-tuning the flow rates of the precipitant and complexing agent, so as to maintain the stability of the particle size. After the reaction stabilized, the material was ready to be collected to obtain seed crystals with an average particle size D50 of 2.5 μm.

[0133] (3) Second reaction:

[0134] A certain amount of the seed crystals obtained in step (2) is added to the reactor, followed by a certain amount of pure water, precipitant, and complexing agent. The mixture is stirred at 180 r / min under a constant temperature of 70℃ to obtain a second base liquid with a pH of 10.50-10.80. An inert gas is introduced into the second base liquid as a protective gas, and a circulating magnetic pump is used to uniformly add the nickel-cobalt-manganese mixed solution, complexing agent, and precipitant to the reactor containing the second base liquid. The second reaction is carried out using a continuous feeding and discharging method. During the reaction, the flow rate of the nickel-cobalt-manganese mixed solution was 4.0% / h of the available volume of the reactor. The pH value of the reaction system was controlled to be 10.45-10.65 and the ammonia concentration was 5.0g / L by finely adjusting the flow rates of the precipitant and complexing agent. The seed crystals obtained in step (2) were continuously added to maintain the stability of the particle size. The seed crystals were added at a rate of 9% / h of the available volume of the reactor. After the reaction stabilized, the material was ready to be collected to obtain the reaction product with an average particle size D50 of 9.967μm.

[0135] (4) Post-processing: The reaction product obtained from the second reaction is centrifuged and washed, and then dried and sieved to obtain nickel-cobalt-manganese ternary cathode material precursor powder.

[0136] In this embodiment, a nickel-cobalt-manganese ternary cathode material precursor is obtained after the above treatment, and its chemical formula is Ni 0.92 Co 0.07 Mn 0.01 (OH)₂, D50 = 9.967 μm, span = 1.413, specific surface area = 9.92 m² 2 / g, tap density = 2.05g / cm³ 3 Microstructure such as Figure 1-3 As shown, the secondary particles of the obtained cathode material precursor are spherical or near-spherical, while the primary particles are spindle-shaped.

[0137] Example 2

[0138] The difference between this embodiment and Embodiment 1 is that the raw material composition of the metal salt solution is different.

[0139] Specifically, in this embodiment, the metal salt solution is prepared by using soluble salts of nickel, cobalt, and manganese as raw materials, and preparing a nickel-cobalt-manganese mixed solution with a concentration of 2.0 mol / L according to the molar ratio Ni:Co:Mn = 93:6:1.

[0140] The chemical formula of the nickel-cobalt-manganese ternary cathode material precursor obtained in this embodiment is Ni 0.93 Co 0.06 Mn 0.01 (OH)₂, D50 = 9.982 μm, span = 1.405, specific surface area = 9.82 m² 2 / g, tap density = 2.06g / cm³ 3 Microstructure such as Figure 6-8 As shown, the secondary particles of the obtained cathode material precursor are spherical or near-spherical, while the primary particles are spindle-shaped.

[0141] Example 3

[0142] The difference between this embodiment and Embodiment 1 is that the raw material composition of the metal salt solution is different.

[0143] Specifically, in this embodiment, the metal salt solution is prepared by using soluble salts of nickel, cobalt, and manganese as raw materials, and preparing a nickel-cobalt-manganese mixed solution with a concentration of 2.0 mol / L according to the molar ratio Ni:Co:Mn = 91:8:1.

[0144] The chemical formula of the nickel-cobalt-manganese ternary cathode material precursor obtained in this embodiment is Ni 0.91 Co 0.08 Mn 0.01 (OH)₂, D50 = 10.132 μm, span = 1.410, specific surface area = 10.0 m² 2 / g, tap density = 2.05g / cm³ 3 Microstructure such as Figure 9-11 As shown, the secondary particles of the obtained cathode material precursor are spherical or near-spherical, while the primary particles are spindle-shaped.

[0145] Example 4

[0146] The difference from Example 1 lies in the different temperatures and stirring speeds of the first and second reactions, as well as the different rates of seed crystal addition and ammonia concentration in the second reaction. Specifically, the steps include the following:

[0147] This embodiment provides a method for preparing a nickel-cobalt-manganese ternary cathode material precursor, including the following steps:

[0148] (1) Raw material preparation:

[0149] Metal salt solution: Soluble salts of nickel, cobalt, and manganese were selected as raw materials, and a mixed nickel-cobalt-manganese solution with a concentration of 2.0 mol / L was prepared according to the molar ratio Ni:Co:Mn = 92:7:1.

[0150] Precipitating agent: Prepare a 10 mol / L sodium hydroxide aqueous solution as a precipitating agent;

[0151] Complexing agent: Prepare an ammonia solution with a concentration of 9 mol / L as a complexing agent.

[0152] (2) First reaction:

[0153] A certain amount of pure water, precipitant, and complexing agent were added to a reactor and stirred at 170 r / min under a constant temperature of 66℃ to obtain a first base liquid with a pH of 11.80. An inert gas was introduced into the first base liquid as a protective gas, and a circulating magnetic pump was used to uniformly add the nickel-cobalt-manganese mixed solution, complexing agent, and precipitant into the reactor containing the first base liquid. The first reaction was carried out using a continuous feeding and discharging method. During the first reaction, the flow rate of the nickel-cobalt-manganese mixed solution was 5.0% / h of the available volume of the reactor. The pH of the reaction system was controlled to be 11.75-11.95 and the ammonia concentration to be 3.9 g / L by fine-tuning the flow rates of the precipitant and complexing agent, so as to maintain the stability of the particle size. After the reaction stabilized, the material was ready to be collected to obtain seed crystals with an average particle size D50 of 2.5 μm.

[0154] (3) Second reaction:

[0155] A certain amount of the seed crystals obtained in step (2) were added to the reactor, along with a certain amount of pure water, precipitant, and complexing agent. The mixture was stirred at 170 r / min under a constant temperature of 66℃ to obtain a second base liquid with a pH of 10.50-10.80. An inert gas was introduced into the second base liquid as a protective gas, and a circulating magnetic pump was used to uniformly add the nickel-cobalt-manganese mixed solution, complexing agent, and precipitant to the reactor containing the second base liquid. The second reaction was carried out using a continuous feeding and discharging method. During the second reaction, the flow rate of the nickel-cobalt-manganese mixed solution was 4.5% / h of the available volume of the reactor. The pH value of the reaction system was controlled to be 10.45-10.65 and the ammonia concentration to be 4.0 g / L by finely adjusting the flow rates of the precipitant and complexing agent. The seed crystals obtained in step (2) were continuously added to maintain the stability of the particle size. The seed crystals were added at a rate of 11% / h of the available volume of the reactor. After the reaction stabilized, the material was ready to be collected to obtain the reaction product with an average particle size D50 of 7.1 μm.

[0156] (4) Post-processing: The reaction product obtained from the second reaction is centrifuged and washed, and then dried and sieved to obtain nickel-cobalt-manganese ternary cathode material precursor powder.

[0157] In this embodiment, a nickel-cobalt-manganese ternary cathode material precursor is obtained after the above treatment, and its chemical formula is Ni 0.92 Co 0.07 Mn 0.01 (OH)₂, D50 = 7.1 μm, span = 1.363, specific surface area = 18.25 m² 2 / g, tap density = 1.88g / cm³ 3 Microstructure such as Figure 12-14 As shown.

[0158] Comparative Example 1

[0159] The difference from Example 3 lies in the different temperatures, stirring speeds, seed crystal addition rates, and ammonia concentrations of the first and second reactions. Specifically, the steps include the following:

[0160] This comparative example provides a method for preparing a nickel-cobalt-manganese ternary cathode material precursor, including the following steps:

[0161] (1) Raw material preparation:

[0162] Metal salt solution: Soluble salts of nickel, cobalt, and manganese were selected as raw materials, and a mixed nickel-cobalt-manganese solution with a concentration of 2.0 mol / L was prepared according to the molar ratio Ni:Co:Mn = 91:8:1;

[0163] Precipitating agent: Prepare a 10 mol / L sodium hydroxide aqueous solution as a precipitating agent;

[0164] Complexing agent: Prepare an ammonia solution with a concentration of 9 mol / L as a complexing agent.

[0165] (2) First reaction:

[0166] A certain amount of pure water, precipitant, and complexing agent were added to a reactor and stirred at 170 r / min under a constant temperature of 64℃ to obtain a first base liquid with a pH of 11.80. An inert gas was introduced into the first base liquid as a protective gas, and a circulating magnetic pump was used to uniformly add the nickel-cobalt-manganese mixed solution, complexing agent, and precipitant into the reactor containing the first base liquid. The first reaction was carried out using a continuous feeding and discharging method. During the first reaction, the flow rate of the nickel-cobalt-manganese mixed solution was 6.5% / h of the available volume of the reactor. The pH of the reaction system was controlled to be 11.75-11.95 and the ammonia concentration to be 4.0 g / L by fine-tuning the flow rates of the precipitant and complexing agent, so as to maintain the particle size stability. After the reaction stabilized, the material was ready to be collected to obtain seed crystals with an average particle size D50 of 2.5 μm.

[0167] (3) Second reaction:

[0168] A certain amount of the seed crystals obtained in step (2) were added to the reactor, along with a certain amount of pure water, precipitant, and complexing agent. The mixture was stirred at 170 r / min under a constant temperature of 64℃ to obtain a second base liquid with a pH of 10.50-10.80. An inert gas was introduced into the second base liquid as a protective gas, and a circulating magnetic pump was used to uniformly add the nickel-cobalt-manganese mixed solution, complexing agent, and precipitant to the reactor containing the second base liquid. The second reaction was carried out using a continuous feeding and discharging method. During the reaction, the flow rate of the nickel-cobalt-manganese mixed solution was 7.0% / h of the available volume of the reactor. The pH value of the reaction system was controlled to be 10.45-10.65 and the ammonia concentration to be 5.5g / L by finely adjusting the flow rates of the precipitant and complexing agent. The seed crystals obtained in step (2) were continuously added to maintain the stability of the particle size. The seed crystals were added at a rate of 7.5% / h of the available volume of the reactor. After the reaction stabilized, the material was ready to be collected to obtain the reaction product with an average particle size D50 of 15.362μm.

[0169] (4) Post-processing: The reaction product obtained from the second reaction is centrifuged and washed, and then dried and sieved to obtain nickel-cobalt-manganese ternary cathode material precursor powder.

[0170] In this comparative example, a nickel-cobalt-manganese ternary cathode material precursor was obtained after the above treatment, with the chemical formula Ni. 0.91 Co 0.08 Mn 0.01 (OH)₂, D50 = 15.362 μm, span = 1.463, specific surface area = 6.53 m² 2 / g, tap density = 2.22g / cm³ 3 Microstructure such as Figure 15-17 As shown.

[0171] Table 1. Differences in reaction conditions between each embodiment and the comparative example.

[0172]

[0173]

[0174] Table 2. Characteristics of the cathode material precursors obtained in each embodiment and comparative example

[0175]

[0176] In Table 2, the particle size of the first type of particles is ≤2μm, and the particle size of the second type of particles is >2μm. The second type of particles also includes type A particles and type B particles. The particle size of type A particles is >2μm and <10μm; the particle size of type B particles is ≥10μm.

[0177] Positive electrode materials were prepared using samples from all examples and comparative examples. The positive electrode material, binder polyvinylidene fluoride (PVDF), and conductive agent (SuperP) were mixed uniformly in a mass ratio of 8:1:1. This mixture was then uniformly coated onto aluminum foil to form a thin layer, dried, and cut into circular pieces as the positive electrode material. A sodium metal sheet was used as the negative electrode, Whatman glass fiber was used as the separator, and 1.0 mol / L NaPF6 / EC (ethylene carbonate) + DMC (dimethyl carbonate) + FEC (fluoroacetic acid) (EC to DMC volume ratio 1:1, FEC accounting for 5% of the total volume) was used as the electrolyte. CR2032 button cells were assembled in an argon-filled glove box. Constant current charge-discharge tests were performed on the button cells. The charge-discharge voltage range was 2.0-3.8V, and the cells were continuously cycled for 400 cycles at a current density of 0.2C (1C = 220 mA / g). The test results are shown in Table 3.

[0178] Table 3. Performance of batteries prepared based on the cathode material precursors in each embodiment and comparative example.

[0179] First charge (0.2C) mAh / g First release (0.2C) mAh / g First-time effect % High-temperature cycling (0.2°C, 45°C) Example 1 242 228 94.21 90% @ 400 weeks Example 2 241 225 93.36 88% @ 400 weeks Example 3 242 227 93.80 89% @ 400 weeks Example 4 238 205 86.13 87% @ 400 weeks Comparative Example 1 238 202 84.87 87% @ 400 weeks

[0180] According to Table 1-3 and Figure 1-17 It is known that the cathode material precursor obtained by the preparation method provided in this application includes particles of different sizes, with a higher proportion of large particles by volume and a higher proportion of small particles (≤2μm in diameter) by number. Furthermore, the resulting cathode material precursor has a wide particle size distribution. A higher proportion of large particles can appropriately improve cycle performance, while a higher proportion of small particles can increase the contact area with the electrolyte, which is beneficial for improving specific capacity. Peak intensity ratio I 101 / I 001 The higher the value, the higher the overall crystallinity and the better the high-temperature cycling performance. Furthermore, the cathode material precursor obtained in this application has a reasonable particle size distribution, which avoids the problem of uneven sintering during cathode material preparation caused by particles of varying sizes in continuous production processes, resulting in excellent overall long-cycle performance of the material.

[0181] In addition, the following relationship exists between D50 / μm and the percentage of the first type of particles in Examples 1-3:

[0182] y = -0.0844x 2 +1.7903x-8.49

[0183] Therefore, by controlling the particle size of secondary particles, the proportion of small particles in the broad-distribution cathode material precursor can be controlled, making the proportion of particles of different sizes in the precursor controllable, thereby effectively regulating the overall physicochemical properties. In summary, this application provides a broad-distribution cathode material precursor with a high proportion of large particles in volume, a high proportion of small particles in number, and a controllable proportion of particles of different sizes, as well as its preparation method. The corresponding cathode material has a high specific capacity and good cycle performance.

[0184] Comparing the experimental data of Example 4 and Example 1, when using the cathode material precursor prepared in Example 1, the corresponding battery exhibits better initial charge-discharge capacity, initial efficiency, and long-cycle performance, balancing both capacity and cycle performance. This is mainly attributed to the high volume percentage of large particles (particle size ≥ 10 μm) and the high number percentage (≥ 91%) of small particles (particle size ≤ 2 μm), resulting in a wide contact area with the electrolyte, numerous active sites, and improved filling density, thus enhancing capacity utilization. Furthermore, I 101 / I 001 >1.0 indicates good crystallinity, with moderate aspect ratio and thickness of primary particles, which is beneficial for lithium-ion transport and structural stability, thus achieving good long-term cycling performance and high-temperature cycling performance. However, in Example 4, the proportion of small particles is too low, affecting its capacity utilization, and I... 101 / I 001 The aspect ratio of the primary particles is relatively large (<1.0), resulting in weaker structural stability. Consequently, its discharge capacity, first-efficiency performance, and cycle performance are all inferior to those of Example 1. Furthermore, the proportion of particles of different sizes in Example 4 is uncontrollable, which is detrimental to the regulation of electrochemical performance.

[0185] Comparing the experimental data of Comparative Example 1 with those of Examples 1-4, the proportion of the first type of particles (small particles) in Comparative Example 1 was very low, only 26.16%, while the proportion of the second type of particles was as high as 64%. Moreover, the proportion of particles of different sizes was uncontrollable. The thickness of the primary particles was large, resulting in a long lithium ion transport path. Therefore, the electrochemical performance of Comparative Example 1 was not as good as that of the Examples.

[0186] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0187] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A cathode material precursor, characterized in that, It includes multiple secondary particles, which include first-type particles and second-type particles, wherein the particle size of the first-type particles is smaller than that of the second-type particles; the particle size distribution span value of the secondary particles is 0.70-1.

60. Among them, the proportion of the first type of particles is greater than the proportion of the second type of particles, and the proportion of the volume of the first type of particles is less than the proportion of the volume of the second type of particles; The particle size of the first type of particles is ≤2μm; the particle size of the second type of particles is >2μm; the volume percentage of the second type of particles is ≥60%; the second type of particles also includes type A particles and type B particles, wherein the particle size of type A particles is >2μm and <10μm; and the particle size of type B particles is ≥10μm.

2. The cathode material precursor according to claim 1, characterized in that, The proportion of the first type of particles is ≥60%.

3. The cathode material precursor according to claim 1 or 2, characterized in that, The cathode material precursor satisfies at least one of the following conditions i to iv: i. The first type of particles accounts for 91%-99% of the total number of particles, while the second type of particles accounts for 1%-9% of the total number of particles; iii. The proportion of Class A particles is 1%-8.99%; iv. The proportion of the B-type particles is 0.01%-0.1%.

4. The cathode material precursor according to claim 1 or 2, characterized in that, The cathode material precursor satisfies at least one of the following aj conditions: b. The average particle size D50 of the secondary particles is 8.4-11.0 μm; c. The specific surface area of ​​the secondary particles is 8-15 m². 2 / g; d. The tap density of the secondary particles is 1.8-2.1 g / cm³. 3 ; e. The peak intensity ratio I between the characteristic peak of the (101) crystal plane and the characteristic peak of the (001) crystal plane of the secondary particle. 101 / I 001 It is 1.0-1.2; f. The cathode material precursor satisfies the following relationship: y= -Ax 2 + Bx - C Where x is the average particle size D50 / μm of the secondary particles, and y is the percentage of the first type of particles (%). A is selected from 0.08-0.09, B is selected from 1.7-1.9, and C is selected from 8-9; g. The secondary particles are spherical or near-spherical in shape; h. The secondary particle is composed of multiple primary particles, and the primary particles are spindle-shaped or sheet-shaped. i. The secondary particle is composed of multiple primary particles, and the length-to-thickness ratio of the primary particle is 3-10; j. The secondary particle is composed of multiple primary particles, and the thickness of the primary particles is 1.0-10.0 nm.

5. The cathode material precursor according to claim 4, characterized in that, In condition i, the secondary particle is composed of multiple primary particles, and the length-to-thickness ratio of the primary particles is 6-7.

6. The cathode material precursor according to claim 4, characterized in that, In condition f, the secondary particle is composed of a plurality of primary particles, and the thickness of the primary particles is 2.0-8.0 nm.

7. The cathode material precursor according to claim 1 or 2, characterized in that, The general chemical formula of the cathode material precursor is Ni. x Co y Mn z M a (OH)2, wherein 0.5≤x<1, 0≤y≤0.5, 0≤z≤0.5, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B and Zn, and 0≤a≤0.

05.

8. The cathode material precursor according to claim 7, characterized in that, 0.8≤x<1, 0≤y≤0.2, 0≤z≤0.2, M includes one or more of Al, Ti, Y, Zr, W, Mg, Ca, Ce, Nb, B and Zn, 0≤a≤0.

05.

9. The cathode material precursor according to claim 8, characterized in that, The cathode material precursor is a layered hydroxide.

10. A method for preparing a cathode material precursor according to any one of claims 1-9, characterized in that, Includes the following steps: A first base solution is prepared by mixing a precipitant and a complexing agent, and then a precipitant, a complexing agent, and a metal salt solution are added to the first base solution to carry out a first reaction to obtain seed crystals. The seed crystals are mixed with a precipitant and a complexing agent to prepare a second base solution. The precipitant, complexing agent, metal salt solution, and the seed crystals are then added to the second base solution to carry out a second reaction to obtain the reaction product. The reaction products were post-processed to obtain the cathode material precursor.

11. The method for preparing the cathode material precursor according to claim 10, characterized in that, The preparation method satisfies at least one of the following conditions (1)-(10): (1) The metal salt includes soluble salts of nickel, cobalt and / or manganese; (2) During the first reaction and the second reaction, the flow rate of the added metal salt solution is 4.0%-7.5% of the available volume of the reaction vessel; (3) The complexing agent includes ammonia water, and the ammonia concentration in the first reaction process is 3.5-4.5 g / L; (4) The ammonia concentration in the second reaction process is 4.5-5.5 g / L; (5) The pH value of the first base solution is 11.50-12.00; (6) The pH value of the reaction system for the first reaction is 11.65-11.95; (7) The pH value of the second substrate is 10.40-10.90; (8) The pH value of the reaction system for the second reaction is 10.3-10.7; (9) The reaction temperature of the first reaction and the second reaction is 50-80℃; (10) Both the first reaction and the second reaction are carried out under stirring, and the stirring speed is 100-200 r / min.

12. The method for preparing the cathode material precursor according to claim 11, characterized in that, The soluble salt includes at least one of nitrates, chlorides, and sulfates.

13. The method for preparing the cathode material precursor according to claim 11, characterized in that, The total concentration of metal ions in the metal salt solution is 1.0-2.0 mol / L.

14. A positive electrode material, characterized in that, It is prepared from the cathode material precursor according to any one of claims 1 to 9.

15. A lithium-ion battery, characterized in that, It is prepared from the cathode material described in claim 14.

16. A lithium battery device, characterized in that, It is prepared from the lithium-ion battery described in claim 15.

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