Cathode material precursors and their preparation methods, cathode materials and lithium-ion batteries

Abstract

This application provides a cathode material precursor and its preparation method, a cathode material, and a lithium-ion battery, relating to the field of new energy technology. The cathode material precursor is a secondary particle composed of primary particles, forming a composite structure. It includes an inner layer arranged radially along the center of the cathode material precursor and an outer layer composed of sheet-like primary particles stacked flat and enclosing the inner layer. The outer layer's sheets are perpendicular to the pressure direction during compaction, resulting in a secondary particle mechanical strength higher than that of common radial or block-shaped secondary particles. After inheriting this structure, the cathode material can achieve a higher compaction density than common secondary particle products, significantly improving the material's energy density. The secondary particles in this application have different sheet orientations between their inner and outer layers. The sintered cathode material inherits this characteristic structure, resulting in different expansion and contraction directions during charge-discharge cycles. This avoids or reduces the formation of cracks that could cause particle structure collapse, thereby improving cycle performance.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to cathode material precursors and their preparation methods, cathode materials, lithium-ion battery cathodes, lithium-ion batteries and related electrical equipment. Background Technology

[0002] With the development of energy storage technology, the threshold requirements for energy density per unit volume of lithium battery materials and cost requirements are rapidly increasing. Against this background, ternary materials are also gradually developing towards high nickel content. Although high nickel ternary materials have advantages in cost and capacity, they also have problems such as poor cycle performance and serious performance degradation.

[0003] Studies have shown that the phase transition of high-nickel ternary materials during charging and discharging can lead to changes in the crystal volume of the cathode material, generating anisotropic stress. This can easily cause primary cracks within and between the crystals, triggering a vicious cycle of crack propagation, which in turn triggers more side reactions. Ultimately, this leads to the collapse and breakage of the entire cathode material structure, resulting in a severe degradation of battery performance.

[0004] Ternary precursors are highly customized standard products for ternary cathode materials and are key materials in the production of ternary cathodes. The characteristics of ternary precursors directly determine the main physicochemical properties of ternary cathode materials, such as particle size, elemental ratio, and impurity content, thereby affecting the core electrochemical performance of lithium batteries, such as consistency, rate performance, energy density, and cycle life.

[0005] Currently, most high-nickel ternary precursors on the market are radially aggregated secondary spherical particles. Although this structure has a large initial capacity, it has poor compressive strength and low compaction density. The stability of the particles after sintering (structural thermal stability) is not high, resulting in poor energy density and cycle performance of the final product. This restricts the application of this morphology in high-energy-density lithium-ion batteries. Summary of the Invention

[0006] The purpose of this application is to provide a cathode material precursor that aims to solve the problems of poor energy density and cycle performance of existing high-nickel ternary materials.

[0007] To achieve the above objectives, this application provides a cathode material precursor, the chemical formula of which is Ni. x Co y Mn z (OH)2, where 0.7≤x<1, 0<y<0.3, 0<z<0.3, x+y+z=1, the structure of the cathode material precursor includes: inner layer and outer layer; the cathode material precursor is a secondary particle composed of primary particles, which is a composite structure;

[0008] Among them, the primary particles in the inner layer are arranged radially along the center of the cathode material precursor;

[0009] The outer layer covers the inner layer, and the primary particles of the outer layer are stacked in layers outside the inner layer.

[0010] Preferably, the growth direction of the inner primary particle is defined by the line R1 connecting the center point of the end of the inner primary particle closest to the geometric center of the secondary particle and the center point of the end of the inner primary particle furthest from the geometric center of the secondary particle. The growth direction of the outer primary particle is defined by the line R2 connecting the center points of the two ends of the outer primary particle that is inclined relative to the outer circumferential surface of the secondary particle. The angle between the growth directions R1 and R of the inner primary particle is θ1, where θ1 is 0±30°. The angle between the growth directions R2 and R of the outer primary particle is θ2, where θ2 is 90±30°. Here, R is the line connecting the geometric center of the primary particle and the geometric center of the secondary particle of the cathode material precursor.

[0011] Preferably, the average thickness of the inner layer accounts for 40% to 55% of the average diameter of the secondary particles in the cathode material precursor; and the average thickness of the outer layer accounts for 45% to 60% of the average diameter of the secondary particles in the cathode material precursor.

[0012] Preferably, the half-width at half-maximum (WHM) of the 101 plane and the half-width at half-maximum (WHM) of the 001 plane in the XRD pattern of the cathode material precursor are ≤0.300° and ≤0.300°, respectively.

[0013] Preferably, the average diameter of the secondary particles in the cathode material precursor is 8 μm to 14 μm;

[0014] Preferably, the average diameter of the secondary particles in the cathode material precursor is 8 μm to 11 μm.

[0015] This application also provides a method for preparing a cathode material precursor, the chemical formula of which is: Ni x Co y Mn z (OH)₂, where 0.7 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, x + y + z = 1, preparation methods include:

[0016] Prepare a metal salt solution according to the ratio of each metal element in the cathode material precursor;

[0017] The metal salt solution, precipitant, and complexing agent are introduced into a reactor containing a first bottom liquid to carry out the first coprecipitation reaction. The pH, complexing agent concentration, and nickel concentration in the supernatant are adjusted until an inner metal hydroxide precipitate that meets the average thickness requirement of the inner layer of the cathode material precursor is obtained.

[0018] The metal salt solution, precipitant, complexing agent, and the aforementioned inner metal hydroxide precipitate are added to the reaction vessel and mixed evenly to form the second base liquid for the second co-precipitation reaction. The pH, complexing agent concentration, and nickel concentration in the supernatant are adjusted until a reaction precipitate slurry that meets the secondary particle size requirements of the cathode material precursor is obtained. The reaction precipitate slurry is then washed and dried to obtain the cathode material precursor.

[0019] Preferably, the nickel concentration in the supernatant of the first coprecipitation reaction is controlled within the range of 250-500 ppm; the nickel concentration in the supernatant of the second coprecipitation reaction is controlled within the range of 50-200 ppm.

[0020] Preferably, the concentration of the complexing agent in the first coprecipitation reaction process is controlled within the range of 3-15 g / L; the concentration of the complexing agent in the second coprecipitation reaction process is controlled within the range of 5-20 g / L.

[0021] Preferably, the pH of the first coprecipitation reaction process and the pH of the second coprecipitation reaction process are controlled by a precipitant; the pH control range of the first coprecipitation reaction process is 10.00-12.00; and the pH control range of the second coprecipitation reaction process is 10.50-12.50.

[0022] Preferably, the reaction temperature for both the first and second coprecipitation reactions is 45-75℃.

[0023] This application also provides a cathode material, the raw materials of which include the above-mentioned cathode material precursor.

[0024] This application also provides a lithium-ion battery cathode, the raw materials of which include the cathode materials described above.

[0025] This application also provides a lithium-ion battery, including the above-described lithium-ion battery positive electrode.

[0026] This application also provides an electrical device, including the aforementioned lithium-ion battery.

[0027] Compared with the prior art, the beneficial effects of this application include:

[0028] The cathode material precursor provided in this application is a secondary particle composed of primary particles, forming a composite structure. It includes an inner layer arranged radially along the center of the cathode material precursor and an outer layer composed of sheet-like primary particles stacked flat and enclosing the inner layer. The outer layer's sheets are perpendicular to the pressure direction during compaction, resulting in a higher mechanical strength for the precursor's secondary particles compared to common radial or block-shaped secondary particles. After inheriting this structure, the cathode material can achieve a higher compaction density than common secondary particle products, significantly improving the material's energy density. The precursor's secondary particles have different sheet orientations between their inner and outer layers. The sintered cathode material inherits this characteristic structure, resulting in different expansion and contraction directions during charge-discharge cycles. This avoids or reduces the formation of cracks that could cause particle structure collapse, thereby improving cycle performance.

[0029] Compared to other precursor structures, this cathode material precursor has higher crystallinity, reducing the presence of dislocations and vacancies in the material itself. The highly ordered layer stacking reduces stress anisotropy, and compared to other materials, it can effectively suppress cracking during charge and discharge, further improving the cycle performance of the cathode material. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0031] Figure 1 This is a schematic cross-sectional view of the cathode material precursor of this scheme;

[0032] Figure 2 This diagram defines the primary particle growth direction of the cathode material precursor in this scheme.

[0033] Figure 3 Here is a SEM image of the cathode material precursor obtained in Example 1;

[0034] Figure 4 This is a cross-sectional view of the cathode material precursor obtained in Example 1;

[0035] Figure 5 The image shows the XRD pattern of the cathode material precursor obtained in Example 1.

[0036] Figure 6 Here is a SEM image of the cathode material precursor obtained in Comparative Example 1;

[0037] Figure 7 Here is a SEM image of the cathode material precursor obtained in Comparative Example 2;

[0038] Figure 8Here is a SEM image of the cathode material precursor obtained in Comparative Example 3;

[0039] Figure 9 The image shows the SEM image of the cathode material precursor obtained in Comparative Example 4. Detailed Implementation

[0040] As used in this article:

[0041] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0042] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0043] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0044] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0045] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0046] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0047] This application provides a cathode material precursor, which is a high-nickel ternary precursor with the chemical formula Ni. x Co y Mn z (OH)₂, where 0.7 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, x + y + z = 1, the cathode material precursor is a secondary particle composed of primary particles, forming a composite structure. High-nickel precursors have higher capacity but poorer cycle performance. This high-nickel precursor, using the precursor structure of this scheme, can improve its cycle performance through the composite structure. This high-nickel precursor can also be doped with metal elements, which are mainly used to improve precursor performance. For example, adding magnesium or zirconium can improve the material's cycle performance; adding aluminum can improve the material's rate performance; adding titanium can improve the material's electronic conductivity.

[0048] The precursor of the cathode material is a key material in the production of cathode materials. It is formed by mixing and sintering with a lithium source to produce the cathode material. Its performance directly determines the core physicochemical properties of the cathode material, and the performance of the cathode material has a good inheritance relationship with the precursor. Specifically, this is manifested in the following ways: 1) Impurities in the precursor will be introduced into the cathode material, affecting the impurity content of the cathode; 2) The particle size and particle size distribution of the precursor directly determine the particle size and particle size distribution of the cathode; 3) The specific surface area and morphology of the precursor directly determine the specific surface area and morphology of the cathode material; 4) The elemental ratio of the precursor directly determines the elemental ratio of the cathode material, etc.

[0049] Please see Figure 1 The structure of the cathode material precursor includes an inner layer and an outer layer covering the inner layer, wherein the primary particles of the inner layer are arranged radially along the center of the cathode material precursor, and the primary particles of the outer layer are stacked in layers outside the inner layer.

[0050] The cathode material precursor provided in this application has a composite structure, including an inner layer arranged radially along the center of the cathode material precursor and an outer layer stacked in layers around the inner layer. The outer layer has flat, primary particle sheets that are perpendicular to the pressure direction during compaction, resulting in a higher mechanical strength for the entire secondary particle structure compared to common radial or block-shaped secondary particles. By inheriting this structure, the cathode material can achieve a higher compaction density than other secondary particle products, significantly improving the material's energy density. The inner and outer layers have different sheet orientations, and the sintered cathode material inherits this structural feature. During charge-discharge cycles, the expansion and contraction directions of the material differ, further improving cycle performance.

[0051] In a preferred embodiment, please refer to Figure 2 , Figure 2 In the cathode material precursor, R is defined as the line connecting the geometric center of the secondary particles and the geometric center of the primary particles. These primary particles include inner or outer layers, and each primary particle possesses an R. Figure 2 The diagram illustrates the case where the R values ​​of the inner primary particles and the outer primary particles are on the same straight line. It should be understood that R is not limited to... Figure 2 In the case of the inner primary particle and the outer primary particle at any position, R can be obtained according to the above definition.

[0052] The growth direction of the inner primary particle is represented by the line R1 connecting the center point of the end of the inner primary particle closest to the geometric center of the secondary particle and the center point of the end furthest from the geometric center of the secondary particle. The angle between the growth direction R1 and R is θ1, which ranges from 0 to 30°. For example, θ1 can be -30°, -25°, -20°, -16°, -15°, -12°, -10°, -5°, -3°, 0°, 2°, 5°, 6°, 8°, 10°, 13°, 15°, 17°, 20°, 21°, 23°, 25°, 26°, 28° or 30°.

[0053] The growth direction is defined by the line R2 connecting the center points of both ends of the outer primary particle, which is inclined relative to the outer circular tangent of the secondary particle. The geometric center of any outer primary particle is considered a point. A secondary particle can obtain an outer circular tangent at this point. Using this outer circular tangent as a reference, the line connecting the center points of the two inclined ends of the sheet-like outer primary particle is R2. The angle between the growth direction R2 and R is θ2, which ranges from 90° to 30°. θ2 can be, for example, 60°, 62°, 65°, 70°, 74°, 75°, 77°, 79°, 80°, 85°, 86°, 90°, 92°, 95°, 96°, 98°, 100°, 102°, 104°, 106°, 107°, 109°, 110°, 111°, 113°, 115°, 116°, 118°, or 120°. The growth direction of the inner and outer primary particles determines the structure of the cathode material precursor.

[0054] In a preferred embodiment, please refer to Figure 1 The ratio of the average thickness D1 of the inner layer to the average diameter D of the secondary particles in the cathode material precursor is 40% to 55%, for example, it can be 40% to 50%, or 45% to 55%, and more specifically, it can be 40%, 41%, 42%, 43%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, or 55%; the ratio of the average thickness D2 of the outer layer to the average diameter D of the secondary particles in the cathode material precursor is 45% to 60%, for example, it can be 45% to 55%, or 50% to 60%, and more specifically, it can be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 55%, 56%, 57%, 58%, or 60%. The sum of the inner layer average thickness D1 and the outer layer average thickness D2 is equal to the average diameter D of the secondary particles of the cathode material precursor. The inner layer average thickness D1 is the diameter of the inner layer, and the cathode material precursor D is the average diameter of the secondary particles of the precursor.

[0055] Because the inner layer is radially arranged, its main function is to increase capacity, while the outer layer is layered and stacked, providing compressive strength. An excessively high proportion of inner layer is detrimental to compressive strength; conversely, an excessively high proportion of outer layer is detrimental to capacity.

[0056] Preferably, in the XRD pattern of the cathode material precursor, the half-width at half maximum (WHM) of the 101 plane is ≤0.300°, and the WHM of the 101 plane can be, for example, less than 0.300°, or less than 0.290°, or less than 0.280°, or less than 0.270°, or less than 0.260°, or less than 0.250°, or less than 0.240°, or less than 0.230°, or less than 0.220°; in the XRD pattern of the cathode material precursor, the half-width at half maximum (WHM) of the 001 plane is ≤0.300°, and the WHM of the 001 plane can be, for example, less than 0.300°, or less than 0.290°, or less than 0.280°, or less than 0.270°, or less than 0.260°, or less than 0.250°, or less than 0.240°, or less than 0.230°, or less than 0.220°.

[0057] Compared to other precursor structures, this cathode material precursor has higher crystallinity, reducing the presence of dislocations and vacancies in the material itself. The highly ordered layer stacking reduces stress anisotropy, and compared to other materials, it can effectively suppress cracking during charge and discharge, further improving the cycle performance of the cathode material.

[0058] Specifically, the average diameter of the secondary particles in the cathode material precursor ranges from 8 μm to 14 μm, indicating that the cathode material precursor consists of large particles. Preferably, the average diameter of the secondary particles in the cathode material precursor ranges from 8 μm to 11 μm.

[0059] This application also provides a method for preparing a cathode material precursor, the chemical formula of which is: Ni x Co y Mn z (OH)₂, wherein 0.7 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, x + y + z = 1, and the preparation method includes:

[0060] Prepare a metal salt solution according to the ratio of each metal element in the cathode material precursor.

[0061] Specifically, based on the chemical formula of the cathode material precursor, the molar ratio of nickel, cobalt, and manganese is obtained. Ni salt, Co salt, and Mn salt solutions of certain concentrations are prepared separately and mixed in a certain proportion to obtain a metal salt solution with a concentration of 1–2.5 mol / L. If doping elements are present, they are prepared in the form of metal salts along with the Ni, Co, and Mn salts.

[0062] The metal salt solution, precipitant, and complexing agent are introduced into a reactor containing a first base liquid to carry out the first coprecipitation reaction. The pH, complexing agent concentration, and nickel concentration in the supernatant are adjusted until an inner metal hydroxide precipitate that meets the average thickness requirements of the inner layer of the cathode material precursor is obtained.

[0063] Specifically, the precipitant can be, for example, NaOH solution, and the complexing agent can be, for example, ammonia. More specifically, the mass concentration of the NaOH solution is 20%–40%, and the mass concentration of the ammonia is 10%–30%. Specifically, the first base solution is obtained by mixing pure water, NaOH solution, and ammonia. The first coprecipitation reaction controls the growth direction of the inner layer primary particles and the average thickness percentage of the inner layer.

[0064] The metal salt solution, precipitant, complexing agent, and the above-mentioned inner metal hydroxide precipitate are added to the reaction vessel and mixed evenly to form the second base liquid for the second coprecipitation reaction. The pH, complexing agent concentration, and nickel concentration in the supernatant are adjusted to obtain a reaction precipitate slurry that meets the requirements for the average diameter of the secondary particles of the cathode material precursor. The reaction precipitate slurry is washed and dried to obtain the cathode material precursor.

[0065] Specifically, the precipitant can be, for example, NaOH solution, and the complexing agent can be, for example, ammonia. More specifically, the mass concentration of the NaOH solution is 20%–40%, and the mass concentration of the ammonia is 10%–30%. The second coprecipitation reaction controls the growth direction of the outer primary particles and the proportion of the average thickness of the outer layer.

[0066] In a preferred embodiment, the nickel concentration in the supernatant of the first coprecipitation reaction is controlled within the range of 250-500 ppm, for example, 250-350 ppm, or 300-400 ppm, or 350-500 ppm, more specifically, it can be (250, 253, 255, 258, 260, 261, 263, 265, 266, 267, 268, 270, 275, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460). The nickel concentration in the supernatant during the second coprecipitation reaction is controlled within the range of 50-200 ppm, for example, it can be 70-150 ppm, or 100-200 ppm, or 50-100 ppm, more specifically (50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195 or 200) ppm.

[0067] In a preferred embodiment, the concentration of the complexing agent in the first coprecipitation reaction process is controlled within the range of 3-15 g / L, for example, 3-10 g / L, or 5-15 g / L, or 5-10 g / L, more specifically, (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) g / L; the concentration of the complexing agent in the second coprecipitation reaction process is controlled within the range of 5-20 g / L, for example, 5-10 g / L, or 10-20 g / L, or 5-15 g / L, more specifically, (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20) g / L.

[0068] In a preferred embodiment, the pH range of the first coprecipitation reaction process is 10.00-12.00, and the pH of the first coprecipitation reaction can be, for example, 10.0, 10.1, 10.3, 10.5, 10.8, 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, or 12.0; the pH range of the second coprecipitation reaction process is 10.50-12.50, and the pH of the second coprecipitation reaction can be, for example, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, 12.4, or 12.5.

[0069] In a preferred embodiment, the reaction temperature of both the first coprecipitation reaction process and the second coprecipitation reaction process is 45-75℃, for example, it can be 45-55℃, or 50-70℃, or 55-75℃, and more specifically, it can be (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74 or 75)℃.

[0070] This application also provides a cathode material, the raw materials of which include the aforementioned cathode material precursor. The cathode material precursor is sintered with a lithium source to obtain the cathode material, the structure and properties of which inherit the structure and properties of the cathode material precursor.

[0071] This application also provides a lithium-ion battery cathode, the raw materials of which include the cathode materials described above.

[0072] This application also provides a lithium-ion battery, including the above-described lithium-ion battery positive electrode.

[0073] This application also provides an electrical device, including the aforementioned lithium-ion battery.

[0074] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0075] Example 1

[0076] Step 1:

[0077] Based on a molar ratio of nickel, cobalt, and manganese of 95:4:1, calculate and weigh nickel sulfate, cobalt sulfate, and manganese sulfate crystals to prepare a 2 mol / L homogeneous ternary metal salt solution.

[0078] Step 2:

[0079] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 55℃ to obtain the first base solution with a pH of 11.80-11.90.

[0080] Under stirring, constant temperature of 55℃, and nitrogen protection, a metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the first base liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0081] During the reaction, the pH was controlled within the range of 11.90-10.80 and the ammonia concentration within the range of 4-12 g / L by finely adjusting the flow rate of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 250-350 ppm, so that the particles grew radially in the first stage; an inner layer of metal hydroxide with an average thickness of 6 μm was obtained.

[0082] Step 3:

[0083] The inner metal hydroxide obtained in step 2 was added to the reaction vessel, along with a certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%). The mixture was stirred evenly at a constant temperature of 55℃ to obtain a second bottom solution with a pH of 11.10-11.00.

[0084] Under stirring, constant temperature of 55℃, and nitrogen protection, metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the second bottom liquid. During the reaction, the mother liquor is discharged through the concentration equipment, and the discharge rate is consistent with the total feed rate.

[0085] During the reaction, the pH was controlled to fluctuate within the range of 11.10-10.50 and the ammonia concentration to fluctuate within the range of 6-13 g / L by fine-tuning the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 70-150 ppm, so that the outer primary particles were laterally stacked in layers; a metal hydroxide reaction precipitate slurry with an average diameter of 11.5 μm was obtained.

[0086] After washing, centrifuging, drying, and demagnetizing by sieving, the Ni composite structure was obtained. 0.95 Co 0.04 Mn 0.01 The scanning electron microscope morphology of the (OH)2 material is shown in the figure below. Figure 3 As shown, its sectional view is as follows Figure 4 As shown, its structure consists of radially grown primary particles in the inner layer and layered stacked primary particle sheets in the outer layer. Its FWHM(001) = 0.232° and FWHM(101) = 0.275°. Please refer to [link / reference]. Figure 5 This indicates that the precursor structure has high crystallinity.

[0087] Example 2

[0088] Step 1: Same as Example 1, and will not be repeated here.

[0089] Step 2:

[0090] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 55℃ to obtain the first base solution with a pH of 11.80-11.90.

[0091] Under stirring, constant temperature of 55℃, and nitrogen protection, a metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the first base liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0092] During the reaction, the pH was controlled within the range of 11.90-10.80 and the ammonia concentration within the range of 4-12 g / L by finely adjusting the flow rate of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 250-350 ppm, so that the particles grew radially in the first stage; an inner layer of metal hydroxide with an average thickness of 7.3 μm was obtained.

[0093] Step 3:

[0094] The inner metal hydroxide obtained in step 2 was added to the reaction vessel, along with a certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%). The mixture was stirred evenly at a constant temperature of 55℃ to obtain a second bottom solution with a pH of 11.10-11.00.

[0095] Under stirring, constant temperature of 55℃, and nitrogen protection, metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the second bottom liquid. During the reaction, the mother liquor is discharged through the concentration equipment, and the discharge rate is consistent with the total feed rate.

[0096] During the reaction, the pH was controlled to fluctuate within the range of 11.10-10.50 and the ammonia concentration to fluctuate within the range of 6-13 g / L by fine-tuning the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 70-150 ppm, so that the outer primary particles were laterally stacked in layers; a metal hydroxide reaction precipitate slurry with an average diameter of 14 μm was obtained.

[0097] After washing, centrifuging, drying, and demagnetizing by sieving, the Ni composite structure was obtained. 0.95 Co 0.04 Mn 0.01 The (OH)2 material has the following structure: the inner layer consists of radially grown primary particles, and the outer layer consists of layered stacked primary particle sheets. Its FWHM(001) = 0.229° and FWHM(101) = 0.287°. The average thickness of the inner layer and the overall average diameter of the final sample are larger than those of Example 1, while the ratio of the average thickness of the inner layer to the overall average particle diameter remains unchanged.

[0098] Example 3

[0099] Step 1: Same as Example 1, and will not be repeated here.

[0100] Step 2:

[0101] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 55℃ to obtain the first base solution with a pH of 11.80-11.90.

[0102] Under stirring, constant temperature of 55℃, and nitrogen protection, a metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the first base liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0103] During the reaction, the pH was controlled within the range of 11.90-10.80 and the ammonia concentration within the range of 4-12 g / L by finely adjusting the flow rate of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 250-350 ppm, so that the particles grew radially in the first stage; an inner layer of metal hydroxide with an average thickness of 4.2 μm was obtained.

[0104] Step 3:

[0105] The inner metal hydroxide obtained in step 2 was added to the reaction vessel, along with a certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%). The mixture was stirred evenly at a constant temperature of 55℃ to obtain a second bottom solution with a pH of 11.10-11.00.

[0106] Under stirring, constant temperature of 55℃, and nitrogen protection, metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the second bottom liquid. During the reaction, the mother liquor is discharged through the concentration equipment, and the discharge rate is consistent with the total feed rate.

[0107] During the reaction, the pH was controlled to fluctuate within the range of 11.10-10.50 and the ammonia concentration to fluctuate within the range of 6-13 g / L by finely adjusting the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 70-150 ppm, so that the outer primary particles were laterally stacked in layers; a metal hydroxide reaction precipitate slurry with an average diameter of 8 μm was obtained.

[0108] After washing, centrifuging, drying, and demagnetizing by sieving, the Ni composite structure was obtained. 0.95 Co 0.04 Mn 0.01 The (OH)2 material has the following structure: the inner layer consists of radially grown primary particles, and the outer layer consists of layered stacked primary particle sheets. Its FWHM(001) = 0.229° and FWHM(101) = 0.287°. The average thickness of the inner layer and the overall average diameter of the final sample are smaller than those of Example 1, while the ratio of the average thickness of the inner layer to the overall average particle diameter remains unchanged.

[0109] Example 4

[0110] Step 1: Same as Example 1, and will not be repeated here.

[0111] Step 2:

[0112] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 55℃ to obtain the first base solution with a pH of 11.80-11.90.

[0113] Under stirring, constant temperature of 55℃, and nitrogen protection, a metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the first base liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0114] During the reaction, the pH was controlled to fluctuate within the range of 11.90-10.80 and the ammonia concentration to fluctuate within the range of 4-12 g / L by finely adjusting the flow rate of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 250-350 ppm, so that the particles grew radially in the first stage; an inner layer of metal hydroxide with an average thickness of 4.6 μm was obtained.

[0115] Step 3:

[0116] The inner metal hydroxide obtained in step 2 was added to the reaction vessel, along with a certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%). The mixture was stirred evenly at a constant temperature of 55℃ to obtain a second bottom solution with a pH of 11.10-11.00.

[0117] Under stirring, constant temperature of 55℃, and nitrogen protection, metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the second bottom liquid. During the reaction, the mother liquor is discharged through the concentration equipment, and the discharge rate is consistent with the total feed rate.

[0118] During the reaction, the pH was controlled to fluctuate within the range of 11.10-10.50 and the ammonia concentration to fluctuate within the range of 6-13 g / L by fine-tuning the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 70-150 ppm, so that the outer primary particles were laterally stacked in layers; a metal hydroxide reaction precipitate slurry with an average diameter of 11.5 μm was obtained.

[0119] After washing, centrifuging, drying, and demagnetizing by sieving, the Ni composite structure was obtained. 0.95 Co 0.04 Mn 0.01The (OH)2 material has the following structure: the inner layer consists of radially grown primary particles, and the outer layer consists of transversely stacked primary particle sheets. The ratio of the average thickness of the inner layer to the overall average diameter is smaller compared to Example 1.

[0120] Comparative Example 1

[0121] Unlike Example 1, in step 3, the pH and ammonia concentration were adjusted to control the pH to fluctuate within the range of 11.10-10.00, the ammonia concentration to fluctuate within the range of 6-13 g / L, and the nickel concentration in the supernatant to fluctuate within the range of 550-600 ppm, thereby obtaining Ni with an average diameter of 11.5 μm. 0.95 Co 0.04 Mn 0.01 (OH)2 material, the final product is as follows Figure 6 As shown, it is difficult for the outermost primary particles to obtain complete lamellae.

[0122] Comparative Example 2

[0123] Unlike Example 1, in step 3, the pH and ammonia concentration were adjusted to control the pH to fluctuate within the range of 11.10-11.50 and the ammonia concentration to fluctuate within the range of 6-13 g / L, while controlling the nickel concentration in the supernatant to be <30 ppm, thus obtaining Ni with an average diameter of 11.5 μm. 0.95 Co 0.04 Mn 0.01 (OH)2 material, the final product is as follows Figure 7 As shown, its outermost primary particles are blocky, and most of their growth direction extends beyond the range of θ2.

[0124] Comparative Example 3

[0125] Step 1: Same as in Example 1, and will not be repeated here.

[0126] Step 2:

[0127] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 55℃ to obtain a bottom solution with a pH of 11.20-11.10.

[0128] Under stirring, constant temperature of 55℃, and nitrogen protection, a metal salt solution (flow rate: 800L / h), NaOH solution (flow rate: 288L / h), and ammonia water (flow rate: 18L / h) are introduced into a reactor containing the bottom liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0129] During the reaction, the pH was controlled within the range of 11.20-10.00 and the ammonia concentration within the range of 3-6 g / L by fine-tuning the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was varied and maintained within the range of 10-50 ppm. The reaction time was controlled at 40-80 h, resulting in a radially shaped ternary precursor with an average diameter of 11.5 μm. Its scanning electron microscopy morphology is shown below. Figure 8 As shown, its surface is porous. The measured FWHM(001) = 0.537° and FWHM(101) = 0.668° indicate that the precursor structure has a low degree of crystallinity.

[0130] Comparative Example 4

[0131] Step 1: Same as in Example 1, and will not be repeated here.

[0132] Step 2:

[0133] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 70℃ to obtain a bottom solution with a pH of 10.80-10.70.

[0134] Under stirring, constant temperature of 70℃, and nitrogen protection, a metal salt solution (flow rate: 800 L / h), NaOH solution (flow rate: 288 L / h), and ammonia water (flow rate: 31 L / h) are introduced into a reactor containing the bottom liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0135] During the reaction, the pH was controlled within the range of 10.80-10.00 and the ammonia concentration within the range of 6-10 g / L by fine-tuning the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was also varied and maintained within the range of 50-100 ppm. This resulted in a disordered ternary precursor structure with an average diameter of 14 μm, as shown in the SEM results of its cross-section. Figure 9 As shown, the primary particle growth direction is random, exceeding θ1 and θ2, while the secondary particle characteristics are disordered large spheres formed by the aggregation of small spheres growing in various directions. The measured FWHM(001) = 0.623° and FWHM(101) = 0.543° indicate that the precursor structure has a low degree of crystallinity.

[0136] Comparative Example 5

[0137] Step 1: Same as Example 1, and will not be repeated here.

[0138] Step 2:

[0139] A certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%) were added to the reaction vessel and stirred evenly at a constant temperature of 55℃ to obtain the first base solution with a pH of 11.80-11.90.

[0140] Under stirring, constant temperature of 55℃, and nitrogen protection, a metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the first base liquid. During the reaction, the mother liquor is discharged through a concentration device, and the discharge rate is consistent with the total feed rate.

[0141] During the reaction, the pH was controlled to fluctuate within the range of 11.90-10.80 and the ammonia concentration to fluctuate within the range of 4-12 g / L by finely adjusting the flow rate of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 250-350 ppm, so that the particles grew radially in the first stage; an inner layer of metal hydroxide with an average thickness of 9.0 μm was obtained.

[0142] Step 3:

[0143] The inner metal hydroxide obtained in step 2 was added to the reaction vessel, along with a certain amount of pure water, NaOH solution (concentration 32wt%), and ammonia water (concentration 21wt%). The mixture was stirred evenly at a constant temperature of 55℃ to obtain a second bottom solution with a pH of 11.10-11.00.

[0144] Under stirring, constant temperature of 55℃, and nitrogen protection, metal salt solution (flow rate: 500L / h), NaOH solution (flow rate: 180L / h), and ammonia water (flow rate: 23L / h) are introduced into the reactor containing the second bottom liquid. During the reaction, the mother liquor is discharged through the concentration equipment, and the discharge rate is consistent with the total feed rate.

[0145] During the reaction, the pH was controlled to fluctuate within the range of 11.10-10.50 and the ammonia concentration to fluctuate within the range of 6-13 g / L by fine-tuning the flow rates of NaOH solution and ammonia water. The nickel concentration in the supernatant of the reaction system was changed and maintained within the range of 70-150 ppm, so that the outer primary particles were laterally stacked in layers; a metal hydroxide reaction precipitate slurry with an average diameter of 11.5 μm was obtained.

[0146] After washing, centrifuging, drying, and demagnetizing by sieving, the Ni composite structure was obtained. 0.95 Co 0.04 Mn 0.01 The (OH)2 material has the following structure: the inner layer consists of radially grown primary particles, and the outer layer consists of transversely stacked primary particle sheets. The average thickness of the inner layer accounts for approximately 78%, and the average thickness of the outer layer accounts for approximately 22%.

[0147] The preparation conditions and performance parameters of the precursors in Examples 1 to 4, and Comparative Examples 1 to 5 are shown in Table 1. According to Table 1, in Examples 2 and 3, the average diameter of the inner layer and the overall particles was adjusted while maintaining the same ratio of average thickness between the inner and outer layers. In Example 4, the ratio of average thickness between the inner and outer layers was adjusted, resulting in precursors with different ratios. In Comparative Example 1, the nickel concentration in the supernatant during preparation was too high, making it difficult to obtain complete lamellar layers in the outer layer of the precursor. In Comparative Example 2, due to the low nickel concentration in the supernatant during preparation, the primary particles of the precursor were blocky, and the growth direction of the primary particles in the outer layer was not layered. In Comparative Example 3, the precursor prepared using existing technology only produced a radial structure without forming an outer layer outside the inner layer. In Comparative Example 4, the precursor synthesized using existing technology produced a precursor structure with disordered angles, without forming an outer layer outside the inner layer. In Comparative Example 5, the ratio of average thickness between the inner and outer layers was adjusted, resulting in a precursor with a ratio exceeding that of this scheme.

[0148] Table 1. Preparation conditions and performance parameters of precursors for each example and comparative example.

[0149]

[0150]

[0151] The precursors of Examples 1 to 4, and Comparative Examples 1 to 5, were used to prepare cathode materials. The performance parameters of the lithium-ion batteries prepared from these cathode materials are shown in Table 2. As can be seen from the comparison in Table 2, when the elemental ratios are the same, the battery of Example 1 exhibits the best performance. This is due to its inner radial and outer transverse layered stacked composite structure, the reasonable average thickness ratio of the inner and outer layers, and high crystallinity, which gives it the highest compaction density and high capacity. Correspondingly, it has the highest volumetric energy density and cycle performance, significantly improving the overall electrochemical performance of the battery. This allows for rapid charging and discharging of the battery and demonstrates high commercial value.

[0152] Table 2 Performance parameters of lithium-ion batteries in each embodiment and comparative example

[0153]

[0154]

[0155] 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.

[0156] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A cathode material precursor, characterized in that, The chemical formula of the cathode material precursor is Ni. x Co y Mn z (OH)2, wherein 0.7≤x<1, 0<y<0.3, 0<z<0.3, x+y+z=1, the structure of the cathode material precursor includes: an inner layer and an outer layer; the cathode material precursor is a secondary particle composed of primary particles, which is a composite structure; The primary particles of the inner layer are arranged radially along the center of the cathode material precursor. The outer layer covers the inner layer, and the primary particles of the outer layer are stacked in layers outside the inner layer; The average diameter of the secondary particles in the cathode material precursor is 8μm~14μm.

2. The cathode material precursor according to claim 1, characterized in that, The growth direction of the inner primary particle is defined by line R1, which connects the center point of the end of the inner primary particle closest to the geometric center of the secondary particle and the center point of the end of the inner primary particle furthest from the geometric center of the secondary particle. The growth direction of the outer primary particle is defined by line R2, which connects the center points of the two ends of the outer primary particle that are inclined relative to the outer circumferential surface of the secondary particle. The angle between the growth directions R1 and R of the inner primary particle is θ1, where θ1 is 0 ± 30°. The angle between the growth directions R2 and R of the outer primary particle is θ2, where θ2 is 90 ± 30°. Here, R is the line connecting the geometric center of the primary particle and the geometric center of the secondary particle of the cathode material precursor.

3. The cathode material precursor according to claim 1 or 2, characterized in that, The average thickness of the inner layer accounts for 40% to 55% of the average diameter of the secondary particles in the cathode material precursor; the average thickness of the outer layer accounts for 45% to 60% of the average diameter of the secondary particles in the cathode material precursor.

4. The cathode material precursor according to claim 3, characterized in that, The half-width at half-maximum (WHM) of the 101 plane and the half-width at half-maximum (WHM) of the 001 plane in the XRD pattern of the cathode material precursor are ≤0.300° and ≤0.300°, respectively.

5. The cathode material precursor according to claim 1, characterized in that, The average diameter of the secondary particles in the cathode material precursor is 8 μm to 11 μm.

6. A method for preparing a cathode material precursor as described in any one of claims 1-5, characterized in that, The chemical formula of the cathode material precursor is: Ni x Co y Mn z (OH)₂, wherein 0.7 ≤ x < 1, 0 < y < 0.3, 0 < z < 0.3, x + y + z = 1, and the preparation method includes: Prepare a metal salt solution according to the ratio of each metal element in the cathode material precursor; The metal salt solution, precipitant, and complexing agent are introduced into a reactor containing a first bottom liquid to carry out a first coprecipitation reaction. The reaction pH, complexing agent concentration, and nickel concentration in the supernatant are adjusted until an inner metal hydroxide precipitate that meets the average thickness requirement of the inner layer of the cathode material precursor is obtained. The metal salt solution, precipitant, complexing agent, and inner metal hydroxide precipitate are added to the reaction vessel and mixed evenly to form a second base liquid for a second coprecipitation reaction. The pH, complexing agent concentration, and nickel concentration in the supernatant are adjusted until a reaction precipitate slurry that meets the secondary particle size requirements of the cathode material precursor is obtained. The reaction precipitate slurry is then washed and dried to obtain the cathode material precursor.

7. The method for preparing the cathode material precursor according to claim 6, characterized in that, The nickel concentration in the supernatant of the first coprecipitation reaction is 250-500 ppm; the nickel concentration in the supernatant of the second coprecipitation reaction is 50-200 ppm.

8. The method for preparing the cathode material precursor according to claim 6, characterized in that, The concentration of the complexing agent in the first coprecipitation reaction process is controlled within the range of 3-15 g / L; the concentration of the complexing agent in the second coprecipitation reaction process is controlled within the range of 5-20 g / L.

9. The method for preparing the cathode material precursor according to claim 6, characterized in that, The pH of the first coprecipitation reaction process and the pH of the second coprecipitation reaction process are controlled by the precipitant; the pH control range of the first coprecipitation reaction process is 10.00-12.00; the pH control range of the second coprecipitation reaction process is 10.50-12.

50.

10. The method for preparing the cathode material precursor according to claim 6, characterized in that, The reaction temperature for both the first and second coprecipitation reactions is 45-75℃.

11. A positive electrode material, characterized in that, Its raw materials include the cathode material precursor as described in any one of claims 1-5.

12. A lithium-ion battery positive electrode, characterized in that, Its raw materials include the cathode material as described in claim 11.

13. A lithium-ion battery, characterized in that, Includes the lithium-ion battery positive electrode as described in claim 12.

14. An electrical-related device, characterized in that, Including the lithium-ion battery as described in claim 13.

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