Lithium-rich manganese-based positive electrode material precursor, preparation method and lithium-rich manganese-based positive electrode material

Abstract

The invention discloses a lithium-rich manganese-based positive electrode material precursor, a preparation method and a lithium-rich manganese-based positive electrode material, the lithium-rich manganese-based positive electrode material precursor comprises secondary particles composed of primary particles, the primary particles comprise sheet-shaped primary particles and lath-shaped primary particles, the average thickness of the sheet-shaped primary particles is 20-80 nm, and the average length of the sheet-shaped primary particles is 100-500 nm; the lath-shaped primary particles are located in the lithium-rich manganese-based positive electrode material precursor, the average thickness of the lath-shaped primary particles is 110-150 nm, and the average length of the lath-shaped primary particles is 800-1200 nm. According to the lithium-rich manganese-based positive electrode material precursor provided by the invention, a structure cooperatively assembled by sheet-shaped and lath-shaped primary particles is constructed, so that the tap density, the structural strength and the reaction activity are favorably considered, and the technical bottleneck that the capacity and the cycle performance of a positive electrode material prepared by a traditional precursor are difficult to consider is overcome; and the comprehensive electrochemical performance of the subsequently prepared positive electrode material can be improved.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and more specifically, to lithium-rich manganese-based cathode material precursors, preparation methods, and lithium-rich manganese-based cathode materials. Background Technology

[0002] With the rapid development of new energy vehicles and large-scale energy storage, the market has placed higher demands on the energy density, cycle life, and cost of lithium-ion batteries. Lithium-rich manganese-based cathode materials, with their theoretical specific capacity exceeding 250 mAh / g and low cost, are considered one of the key cathode materials for next-generation high-energy-density lithium-ion batteries. However, their commercial application still faces a series of severe challenges: First, problems such as low initial-cycle efficiency, severe voltage decay, and poor cycle performance have long existed; second, the pursuit of high capacity often leads to low material compaction density, thus limiting the improvement of battery volumetric energy density. The root cause of these problems is closely related to the instability of the material's crystal structure and the phase transition during lithium-ion insertion / extraction.

[0003] As the foundation for the preparation of lithium-rich manganese-based materials, the physical and chemical properties of the precursor (usually manganese-nickel-based hydroxide), such as morphology, particle size, porosity, tap density, and microstructure, directly determine the performance of the final sintered product. Currently, precursors prepared by conventional co-precipitation methods are mostly spherical secondary particles formed by the agglomeration of primary particles. To increase the specific surface area and thus enhance reactivity, it is usually necessary to reduce the size of the primary particles or increase the porosity, but this often leads to a decrease in the tap density and a weakening of the structural strength of the precursor. During subsequent high-temperature sintering and battery cycling, the cathode material derived from this structurally unstable precursor is prone to particle breakage or structural collapse, accelerating performance degradation. Conversely, simply pursuing high tap density and high structural strength may sacrifice the material's reactivity and specific capacity.

[0004] Therefore, how to design and prepare a lithium-rich manganese-based precursor with both high reactivity and high structural stability, and achieve synergistic optimization of the capacity, cycle life, and compaction density of the cathode material prepared from it, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a lithium-rich manganese-based cathode material precursor, a preparation method, and a lithium-rich manganese-based cathode material, which is beneficial for balancing density and reactivity.

[0006] This invention is implemented as follows: In a first aspect, the present invention provides a lithium-rich manganese-based cathode material precursor, comprising secondary particles composed of primary particles, wherein the primary particles include sheet-like primary particles and strip-like primary particles, wherein the sheet-like primary particles have an average thickness of 20-80 nm and an average length of 100-500 nm; and the strip-like primary particles are located inside the lithium-rich manganese-based cathode material precursor, wherein the strip-like primary particles have an average thickness of 110 nm-150 nm and an average length of 800 nm-1200 nm.

[0007] In an optional embodiment, the secondary particles consist of a core, a middle layer, and a surface layer from the inside out, and the porosity of the core and the surface layer is less than that of the middle layer. And / or, the secondary particles comprise, from the inside out, a core, a middle layer, and a surface layer, wherein the average pore size of the core and the surface layer is smaller than the average pore size of the middle layer; And / or, the secondary particles consist of a core, a middle layer and a surface layer from the inside out, and the lath-shaped primary particles are mainly distributed in the middle layer; And / or, in the cross-section of the secondary particles, the area of ​​the lath-shaped primary particles accounts for 30% to 80% of the total cross-sectional area.

[0008] In an optional embodiment, the sphericity of the secondary particles is 0.8 to 0.9; And / or, the precursor of the lithium-rich manganese-based cathode material has the molecular formula Mn. x Ni 1-x (OH)₂, where 0.5 ≤ x ≤ 0.8; And / or, the Dv50 of the lithium-rich manganese-based cathode material precursor is 5.0~7.0 μm; And / or, the porosity of the lithium-rich manganese-based cathode material precursor is 3.0%~6.0%; And / or, the radial distance of the lithium-rich manganese-based cathode material precursor is 0.3~0.4; And / or, the specific surface area of ​​the lithium-rich manganese-based cathode material precursor is 22~36 m². 2 / g; And / or, the average aspect ratio of the secondary particles is 1.1 to 1.2; And / or, the tap density of the lithium-rich manganese-based cathode material precursor is 1.3~1.7 g / cm³. 3 .

[0009] Secondly, the present invention provides a method for preparing the lithium-rich manganese-based cathode material precursor described in the foregoing embodiments, comprising: During the nucleation stage, under a protective atmosphere and stirring conditions, a mixed metal salt solution and a precipitant solution are added concurrently to the bottom liquid containing the precipitant, and the pH of the reaction system is maintained at 10.0~11.0 to obtain a slurry. During the growth stage, under a protective atmosphere and stirring conditions, the mixed metal salt solution was continuously added, and the flow rate of the precipitant solution was gradually reduced so that the pH of the reaction system gradually decreased to 8.67~9.33. The pH was maintained at 8.67~9.33 until the Dv50 reached 2.0~4.0um, thus obtaining the second-stage slurry. Structure-induced slurry containing lath-shaped primary particles was obtained by increasing the flow rate of the mixed metal salt solution and precipitant under a protective atmosphere and stirring conditions. This resulted in a pH increase of 0.3 to 1.0 in the reaction system compared to the two-stage slurry within 1 to 10 minutes. Continue growth, and under a protective atmosphere and stirring conditions, continue to add mixed metal salt solution to the structure-inducing slurry while reducing the flow rate of the precipitant solution to maintain the pH of the reaction system at 8.67~9.33, to obtain the target slurry; In the post-processing stage, the target slurry is sequentially aged, washed, and dried under a protective atmosphere to obtain the lithium-rich manganese-based cathode material precursor.

[0010] In an optional embodiment, the mixed metal salt solution includes nickel ions and manganese ions, and the molar ratio of nickel to manganese is (1-x):x, 0.5≤x≤0.8; And / or, the total concentration of metal ions in the mixed metal salt solution is 100 g / L to 120 g / L; And / or, the precipitant is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide; And / or, the pH of the substrate solution is 10.10~10.70; And / or, the bottom liquid accounts for 80% to 95% of the volume of the reactor in which it is located.

[0011] In an optional embodiment, the flow rate of the mixed metal salt solution is 0.097 mol / h / L during the nucleation and growth stages. 反应器 ~0.103 mol / h / L 反应器 ; And / or, the stirring speed is 450 rpm to 550 rpm; And / or, the nucleation time is 30 min to 120 min.

[0012] In an optional embodiment, a protective gas is introduced into the reactor during the nucleation stage, growth stage, structure induction, and continued growth steps, with the amount of protective gas introduced per hour being 1% to 3% of the reactor volume; And / or, the post-processing step introduces protective gas into the equipment, and the amount of protective gas introduced per hour is 1% to 5% of the equipment volume.

[0013] In an optional implementation, the time for the structure induction step is 1 to 60 minutes; And / or, the rate of pH decrease during the growth phase is 0.02 / 30min to 0.06 / 30min; And / or, the pH of the structure induction step is lower than the pH of the nucleation stage.

[0014] And / or, in the structure induction step and the continued growth step, the flow rate of the mixed metal salt solution is 0.133 mol / h / L. 反应器 ~0.183 mol / h / L 反应器 .

[0015] In an optional embodiment, during the continued growth step, when the solid content of the reaction system reaches 400-500 g / L for the first time, the solid content is adjusted to 150 g / L-300 g / L, and then the co-precipitation step is continued. And / or, the solid content of the target slurry is 550 g / L to 750 g / L; And / or, use a Lab colorimeter to test the color of the target slurry, with an L value of 50-60, an a value of 2-7, and a b value of 19-24.

[0016] Thirdly, the present invention provides a lithium-rich manganese-based cathode material, the raw material of which includes the lithium-rich manganese-based cathode material precursor described in any one of the foregoing embodiments.

[0017] The present invention has at least the following beneficial effects: The present invention provides a lithium-rich manganese-based cathode material precursor, which, by constructing a structure synergistically assembled from sheet-like and strip-like primary particles, is beneficial to balancing micro density, structural strength and reactivity. This overcomes the technical bottleneck of traditional precursor-prepared cathode materials, which struggle to balance capacity and cycle performance, and is conducive to improving the overall electrochemical performance of the subsequently prepared cathode materials. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared in Example 1 are shown.

[0020] Figure 2 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared in Example 2 are shown.

[0021] Figure 3 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared in Example 3 are shown.

[0022] Figure 4 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared for Comparative Example 1 are shown.

[0023] Figure 5 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared for Comparative Example 2 are shown.

[0024] Figure 6 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared for Comparative Example 3 are shown.

[0025] Figure 7 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared for Comparative Example 4 are shown.

[0026] Figure 8 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared in Example 4 are shown.

[0027] Figure 9 The surface and cross-sectional morphology of the lithium-rich manganese-based cathode material precursor prepared for Comparative Example 5 are shown. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0029] This invention provides a lithium-rich manganese-based cathode material precursor, comprising secondary particles composed of primary particles. The primary particles include sheet-like primary particles and strip-like primary particles. The sheet-like primary particles have an average thickness of 20-80 nm and an average length of 100-500 nm. The strip-like primary particles are located inside the lithium-rich manganese-based cathode material precursor, and have an average thickness of 110 nm-150 nm and an average length of 800 nm-1200 nm.

[0030] The present invention provides a lithium-rich manganese-based cathode material precursor, which, by constructing a structure synergistically assembled from sheet-like and strip-like primary particles, is beneficial to balancing micro density, structural strength and reactivity. This overcomes the technical bottleneck of traditional precursor-prepared cathode materials, which struggle to balance capacity and cycle performance, and is conducive to improving the overall electrochemical performance of the subsequently prepared cathode materials.

[0031] First, the average thickness of the plate-like primary particles in the precursor is 20~80 nm, such as 20 nm, 26.7 nm, 33.3 nm, 40 nm, 46.7 nm, 53.3 nm, 60 nm, 66.7 nm, 73.3 nm, and 80 nm; the average length is 100~500 nm, such as 100 nm, 144 nm, 189 nm, 233 nm, 278 nm, 322 nm, 367 nm, 411 nm, 456 nm, and 500 nm. The plate-like primary particles are thin, which greatly increases the specific surface area of ​​the precursor, enhances its solid-phase contact and reaction efficiency with the lithium source during high-temperature sintering, promotes the formation of a highly active lithium-rich phase, and thus effectively improves the specific capacity of the cathode material. Secondly, the internally interwoven lath-shaped primary particles have an average thickness of 110–150 nm, such as 110 nm, 114 nm, 118 nm, 122 nm, 126 nm, 130 nm, 134 nm, 138 nm, 142 nm, 146 nm, and 150 nm; and an average length of 800–1200 nm, such as 800 nm, 844 nm, 889 nm, 933 nm, 978 nm, 1022 nm, 1067 nm, 1111 nm, 1156 nm, and 1200 nm. This structure forms a three-dimensional reinforcing framework, significantly improving the mechanical strength and tap density of the secondary particles. Higher tap density can be achieved during electrode rolling, increasing the battery's volumetric energy density. Simultaneously, this framework structure effectively buffers internal stress during charging and discharging, suppressing particle cracking and structural collapse, and extending cycle life. When the thickness of the lath-shaped primary particles is less than 110 nm, it may lead to insufficient support strength; when it is greater than 150 nm, it will excessively occupy the internal space, compress the ion transport channels, and may also damage the sphericity of the secondary particles. By controlling the spatial distribution and morphology parameters of the two types of primary particles, it is beneficial to achieve synergistic optimization of high capacity, high density, and long cycle life of the cathode material prepared from this precursor, providing key material support for high-performance lithium-ion batteries.

[0032] In an optional embodiment, the secondary particles, from the inside out, comprise a core, a middle layer, and a surface layer, with the porosity of the core and surface layer being lower than that of the middle layer. The cathode material prepared from this precursor inherits its porosity characteristics, which are positively correlated with the mechanical properties of the precursor. The lower porosity of the precursor's core and surface layer results in a denser structure, effectively enhancing the overall mechanical strength and surface wear resistance of the secondary particles. This is beneficial for improving the tap density of the cathode material prepared from it and the structural integrity during electrode processing. Meanwhile, the middle layer of the precursor maintains a high porosity, allowing the cathode material prepared from it to form internal "buffer channels" that can accommodate volume changes during lithium-ion insertion / extraction, alleviating stress concentration and inhibiting crack propagation to the surface. Simultaneously, the high porosity of the middle layer of the cathode material facilitates electrolyte wetting and longitudinal lithium-ion diffusion, improving reaction uniformity.

[0033] In an optional embodiment, the secondary particles, from the inside out, comprise a core, a middle layer, and a surface layer. The average pore size of the core and surface layer is smaller than that of the middle layer. The cathode material prepared from this precursor inherits its porosity characteristics, which are positively correlated with the mechanical properties of the precursor. The smaller average pore size of the precursor's core and surface layer improves local structural density and interface stability, helping to enhance the anti-breakage ability of the cathode material particles prepared from it and reducing the side reaction area between the surface layer and the electrolyte. The middle layer of the precursor has a larger pore size, enabling the cathode material prepared from it to form a highly efficient internal ion conduction network, promoting electrolyte penetration and rapid lithium ion migration, and reducing concentration polarization. This structure is particularly suitable for cathode materials operating at high rates, ensuring that the reactive centers fully participate in the electrochemical reaction. Simultaneously, the large-pore middle layer and the lath-like structure work synergistically, providing expansion buffer space for the cathode material prepared from it while maintaining framework continuity, preventing performance degradation due to pore collapse, and achieving simultaneous improvement in kinetic performance and cycle stability.

[0034] In an optional embodiment, the secondary particles, from the inside out, comprise a core, a middle layer, and a surface layer, with the lath-shaped primary particles mainly distributed in the middle layer. Concentrating the lath-shaped primary particles in the middle layer allows for the construction of a highly efficient mechanical support framework in critical areas. The middle layer, as a transition zone connecting the core and the surface layer, bears the maximum stress gradient during charging and discharging, and is the main path for crack initiation and propagation. Concentrating the lath-shaped structures in this region effectively bridges the primary particles, forming a continuous, high-strength network, significantly improving resistance to deformation and suppressing the generation of internal microcracks. Simultaneously, this layout avoids the potential decrease in specific surface area and reduced reactivity caused by excessive exposure of the lath structure on the surface, preserving the high reactivity advantages of the surface lamellar structure.

[0035] In an optional embodiment, the area of ​​the lath-shaped primary particles in the cross-section of the secondary particles accounts for 30% to 80% of the total cross-sectional area, for example, 30%, 35.6%, 41.1%, 46.7%, 52.2%, 57.8%, 63.3%, 68.9%, 74.4%, and 80%. A moderate distribution of the lath-shaped primary particles helps maintain reasonable porosity while ensuring support, which is beneficial for electrolyte penetration and lithium-ion transport. When the lath area ratio is less than 30%, the skeleton density is insufficient, making it difficult to effectively bear internal stress and limiting the reinforcing effect; exceeding 80% leads to excessive internal density, compressing pore space, hindering lithium-ion transport, and potentially causing localized stress concentration. Controlling it within the 30% to 80% range allows for the formation of a continuous, penetrating support network, significantly improving mechanical strength and tap density, while retaining sufficient pores for electrolyte penetration and ion migration.

[0036] In an optional embodiment, the sphericity of the secondary particles is 0.8 to 0.9, for example, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, or 0.90. High sphericity is beneficial for improving powder flowability and bulk density, and for improving coating uniformity. In addition, the regular shape reduces stress concentration, and combined with the lath-shaped primary particles, it is more conducive to enhancing structural stability.

[0037] In an optional embodiment, the precursor of the lithium-rich manganese-based cathode material has the molecular formula Mn. x Ni 1-x (OH)2, where 0.5≤x≤0.8, for example 0.50, 0.53, 0.57, 0.60, 0.63, 0.67, 0.70, 0.73, 0.77, 0.80; this component balances high capacity and low cost, high manganese content improves safety and lithium layer stability, moderate nickel ensures conductivity and reactivity, which is conducive to the formation of lithium-rich phase structure, achieving a balance between high specific capacity and good cycle performance.

[0038] In an optional embodiment, the Dv50 of the lithium-rich manganese-based cathode material precursor is 5.0~7.0 μm, for example, 5.0 μm, 5.2 μm, 5.4 μm, 5.6 μm, 5.8 μm, 6.0 μm, 6.2 μm, 6.4 μm, 6.6 μm, 6.8 μm, and 7.0 μm; the moderate particle size balances the reaction activity and processing performance, avoiding excessively fine particles that lead to high residual alkali or excessively coarse particles that affect sintering uniformity.

[0039] In an optional embodiment, the porosity of the lithium-rich manganese-based cathode material precursor is 3.0% to 6.0%, for example, 3.0%, 3.3%, 3.7%, 4.0%, 4.3%, 4.7%, 5.0%, 5.3%, 5.7%, and 6.0%; appropriate porosity ensures electrolyte permeation and ion transport while maintaining the strength of the particle structure.

[0040] In an optional embodiment, the pitch of the lithium-rich manganese-based cathode material precursor is 0.3~0.4, for example 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40; the narrow particle size distribution ensures uniform particle size, improves powder filling and coating uniformity, reduces electrode defects, and improves the crystallization consistency of the cathode material.

[0041] In an optional embodiment, the specific surface area of ​​the lithium-rich manganese-based cathode material precursor is 22~36 m². 2 / g, for example 22 m² / g, 24 m² / g, 25 m² / g, 27 m² / g, 28 m² / g, 30 m² / g, 31 m² / g, 33 m² / g, 34 m² / g, 36 m² / g; contributed by fine, thin, sheet-like primary particles, providing a sufficient reaction interface to promote the full reaction of the lithium source, improving sintering efficiency and material capacity. This avoids the moisture absorption and side reaction problems caused by excessively high specific surface area, which is beneficial for balancing activity and stability.

[0042] In an optional embodiment, the average aspect ratio of the secondary particles of the lithium-rich manganese-based cathode material precursor is 1.1 to 1.2, for example, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, or 1.20; the near-spherical regular morphology is beneficial to improving flowability and compaction performance.

[0043] In an optional embodiment, the tap density of the lithium-rich manganese-based cathode material precursor is 1.3~1.7 g / cm³. 3 Examples of high tap density include 1.30 g / cm³, 1.34 g / cm³, 1.38 g / cm³, 1.42 g / cm³, 1.46 g / cm³, 1.50 g / cm³, 1.54 g / cm³, 1.58 g / cm³, 1.62 g / cm³, 1.66 g / cm³, and 1.70 g / cm³. High tap density is beneficial for increasing volumetric energy density.

[0044] This invention also provides a method for preparing the lithium-rich manganese-based cathode material precursor described in the foregoing embodiments, comprising: During the nucleation stage, under a protective atmosphere and stirring conditions, a mixed metal salt solution and a precipitant solution are added concurrently to the bottom liquid containing the precipitant, and the pH of the reaction system is maintained at 10.0~11.0, for example 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, to obtain a slurry. During the growth stage, under a protective atmosphere and stirring conditions, the mixed metal salt solution is continuously added while the flow rate of the precipitant solution is gradually reduced, causing the pH of the reaction system to gradually decrease to 8.67–9.33, for example, 8.67, 8.71, 8.76, 8.80, 8.84, 8.89, 8.93, 8.98, 9.02, 9.07, 9.11, 9.16, 9.20, 9.24, 9.29, and 9.33. The pH is maintained at 8.67–9.33 until the Dv50 reaches 2.0–4.0 μm, for example, 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, and 4.0 μm, thus obtaining the two-stage slurry. Structure-induced slurry containing lath-shaped primary particles was obtained by increasing the flow rates of the mixed metal salt solution and precipitant under a protective atmosphere and stirring conditions. This resulted in a pH increase of 0.3 to 1.0 compared to the second-stage slurry within 1 to 10 minutes, for example, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min. Continue growth, and under a protective atmosphere and stirring conditions, continue to add mixed metal salt solutions to the structure-inducing slurry while reducing the flow rate of the precipitant solution to maintain the pH of the reaction system at 8.67~9.33, for example 8.67, 8.71, 8.76, 8.80, 8.84, 8.89, 8.93, 8.98, 9.02, 9.07, 9.11, 9.16, 9.20, 9.24, 9.29, 9.33, to obtain the target slurry; In the post-processing stage, the target slurry is sequentially aged, washed, and dried under a protective atmosphere to obtain the lithium-rich manganese-based cathode material precursor.

[0045] The method for preparing lithium-rich manganese-based cathode material precursors provided by this invention achieves precise construction of the precursor microstructure under complexing agent-free conditions through multi-stage synergistic control of pH and flow rate, exhibiting both high reactivity and high structural stability. The method consists of five stages: nucleation, growth, structure induction, continued growth, and post-treatment. The process parameters at each stage are closely coordinated to precisely guide the evolution of crystal morphology.

[0046] During the nucleation stage, the pH is maintained at 10.0–11.0 to promote rapid nucleation of metal ions, forming a sufficient number of uniformly distributed initial crystal nuclei, laying the foundation for subsequent controllable growth. After entering the growth stage, the pH is gradually reduced to 8.67–9.33 and stabilized to create a thermodynamic environment conducive to the two-dimensional lateral extension of layered hydroxides, promoting the orderly growth of plate-like primary particles and constructing a spherical secondary particle framework. When Dv50 reaches 2.0–4.0 μm, "structure induction" is implemented by instantaneously increasing the pH by 0.3–1.0 (pH pulse) and increasing the feed flow rate, generating localized high supersaturation in a short time. This breaks the steady-state growth mode and selectively stimulates rapid one-dimensional growth at the edges of primary particles, forming in-situ lath-like structures interspersed within the particles as a reinforcing framework. Subsequently, the original pH conditions are restored during the continued growth stage, allowing the surface to continue extending in a plate-like structure, achieving a multi-level structural assembly that is "strong internally and active externally." Finally, aging, washing, and drying under a protective atmosphere suppress changes in manganese valence state and the formation of impurities, ensuring product purity and performance consistency.

[0047] In an optional embodiment, the mixed metal salt solution includes nickel ions and manganese ions, and the molar ratio of nickel to manganese is (1-x):x, 0.5≤x≤0.8, which is beneficial to optimizing the crystal structure and electrochemical performance of the material and improving the cycle stability and specific capacity of the cathode material.

[0048] In an optional embodiment, the total concentration of metal ions in the mixed metal salt solution is 100 g / L to 120 g / L, for example, 100 g / L, 102 g / L, 104 g / L, 106 g / L, 108 g / L, 110 g / L, 112 g / L, 114 g / L, 116 g / L, 118 g / L, or 120 g / L, which is beneficial for improving reaction efficiency and product consistency.

[0049] In an optional embodiment, the precipitant is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide.

[0050] In an optional embodiment, the pH of the base solution is 10.10~10.70, for example 10.10, 10.17, 10.23, 10.30, 10.37, 10.43, 10.50, 10.57, 10.63, 10.70, which effectively promotes uniform co-precipitation and reduces the generation of impurities.

[0051] In an optional embodiment, the bottom liquid accounts for 80% to 95% of the volume of the reactor, for example, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, or 95%, which enhances the stability of the reaction system and facilitates the formation of precursors with uniform particle size and high tap density.

[0052] In an optional embodiment, the flow rate of the mixed metal salt solution is 0.097 mol / h / L during the nucleation and growth stages. 反应器 ~0.103 mol / h / L 反应器 For example, 0.097 mol / h / L 反应器 0.098 mol / h / L 反应器 0.099mol / h / L 反应器 0.100 mol / h / L 反应器 0.101 mol / h / L 反应器 0.102 mol / h / L 反应器 0.103 mol / h / L 反应器 This is beneficial for the uniform distribution of reactants and the stability of the reaction rate, so as to form a precursor with uniform particle size and high crystallinity, in which L 反应器 This refers to the volume of a unit reactor, measured in liters (L).

[0053] In an optional embodiment, the stirring speed is 450 rpm to 550 rpm, such as 450 rpm, 461 rpm, 472 rpm, 483 rpm, 494 rpm, 506 rpm, 517 rpm, 528 rpm, 539 rpm, and 550 rpm, which further promotes the uniform mixing of the reaction system, reduces local supersaturation, and improves the consistency and purity of the product.

[0054] In an optional embodiment, the nucleation time is 30 min to 120 min, for example 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min. This optimizes the formation process of crystal nuclei, ensures a reasonable distribution of the number and size of crystal nuclei, and thus improves the electrochemical performance and structural stability of the final material.

[0055] In an optional embodiment, a protective gas is introduced into the reactor during the nucleation stage, growth stage, structure induction, and continued growth steps. The amount of the protective gas introduced per hour is 1% to 3% of the reactor volume, for example, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%, to reduce material oxidation.

[0056] In an optional implementation, the post-processing step introduces protective gas into the equipment, and the amount of protective gas introduced per hour is 1% to 5% of the equipment volume.

[0057] In an optional embodiment, the time for the structure induction step is 1 to 60 min, for example 1 min, 7.6 min, 14.1 min, 20.7 min, 27.2 min, 33.8 min, 40.3 min, 46.9 min, 53.4 min, and 60 min; this ensures the formation and stability of lath-shaped primary particles, thereby optimizing the microstructure of the material.

[0058] In an optional embodiment, the pH decrease rate during the growth phase is 0.02 / 30 min to 0.06 / 30 min, for example 0.02 / 30 min, 0.024 / 30 min, 0.029 / 30 min, 0.033 / 30 min, 0.038 / 30 min, 0.042 / 30 min, 0.047 / 30 min, 0.051 / 30 min, 0.056 / 30 min, 0.06 / 30 min. This gradual pH adjustment helps to form uniform precursor particles with controllable particle size.

[0059] In an optional implementation, the pH of the structure induction step is lower than that of the nucleation stage to avoid the generation of a large number of fine crystal nuclei.

[0060] In an optional embodiment, the flow rate of the mixed metal salt solution is 0.133 mol / h / L during the structure induction step and the continued growth step. 反应器 ~0.183 mol / h / L 反应器 For example, 0.133 mol / h / L 反应器 0.138 mol / h / L 反应器 0.144 mol / h / L 反应器 0.149 mol / h / L 反应器 0.154 mol / h / L 反应器 0.160 mol / h / L 反应器 0.165 mol / h / L 反应器 0.170 mol / h / L 反应器0.176 mol / h / L 反应器 0.181 mol / h / L 反应器 0.183 mol / h / L 反应器 Increasing the flow rate of the mixed metal salt solution is beneficial to the formation of lath-shaped primary particles and the growth of secondary particles.

[0061] In an optional embodiment, during the continued growth step, when the solid content of the reaction system first reaches 400-500 g / L, for example 400 g / L, 411 g / L, 422 g / L, 433 g / L, 444 g / L, 456 g / L, 467 g / L, 478 g / L, 489 g / L, or 500 g / L, the solid content is adjusted to 150 g / L-300 g / L, for example 150 g / L, 167 g / L, 183 g / L, 200 g / L, 217 g / L, 233 g / L, 250 g / L, 267 g / L, 283 g / L, or 300 g / L, and then the co-precipitation step is continued to reduce the number of particles, which is beneficial to particle growth.

[0062] In an optional embodiment, the solid content of the target slurry is 550 g / L to 750 g / L, for example, 550 g / L, 572 g / L, 594 g / L, 617 g / L, 639 g / L, 661 g / L, 683 g / L, 706 g / L, 728 g / L, or 750 g / L.

[0063] In an optional implementation, the color of the target slurry is tested using a Lab colorimeter, with an L value of 50-60, such as 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60; an a value of 2-7, such as 2, 2.6, 3.1, 3.7, 4.2, 4.8, 5.3, 5.9, 6.4, 7; and a b value of 19-24, such as 19, 19.6, 20.1, 20.7, 21.2, 21.8, 22.3, 22.9, 23.4, 24. The degree of oxidation of the slurry can be preliminarily assessed based on its color.

[0064] The present invention also provides a lithium-rich manganese-based cathode material, the raw material of which includes the lithium-rich manganese-based cathode material precursor described in any one of the foregoing embodiments.

[0065] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0066] Example 1 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material precursor, the specific steps of which are as follows: Step (1): Prepare the base solution by adding sodium hydroxide solution to a reactor containing water and adjusting the pH of the base solution to 10.34. The reactor used has a volume of 600L and is equipped with a concentrator for solidification. The base solution accounts for 90% of the volume of the reactor.

[0067] Step (2), nucleation stage: A mixed metal salt solution consisting of nickel sulfate crystals, manganese sulfate crystals, and water is prepared, with a nickel to manganese molar ratio of 35:65 and a total metal ion concentration of 112.5 g / L. The average flow rate of the mixed metal salt solution added per liter of reactor is 0.10 mol / h / L (i.e., 60 mol / h). The reactor temperature is maintained at 50℃, the stirring rate is 465 rpm, and the nitrogen flow rate per hour is 1.67% of the reactor volume. Simultaneously, a 10.8 mol / L sodium hydroxide solution is introduced to maintain the pH at 10.34 ± 0.03 for 90 min, resulting in a slurry.

[0068] Step (3), growth stage: under the condition that the flow rate of the mixed metal salt solution remains unchanged, the flow rate of the sodium hydroxide solution is reduced so that the pH gradually decreases to 8.90±0.03 at a rate of 0.025 / 30min. The mixed metal salt solution and precipitant solution are added in parallel and the pH of the reaction system is maintained at 8.90±0.03 until Dv50 reaches 3.5um, and the second-stage slurry is obtained.

[0069] Step (4): Increase the flow rate of sodium hydroxide solution to raise the pH by 1.0 within 3 min, and at the same time increase the flow rate of mixed metal salt solution added to the reactor to 0.167 mol / h / L; after the high pH is maintained for 10 min (excluding the 3 min of pH increase), the structure-induced slurry is obtained.

[0070] Step (5): Reduce the flow rate of sodium hydroxide solution to restore the pH to 8.90±0.03. Maintain the flow rate of mixed metal salt solution at 0.167 mol / h / L. Continue to add mixed metal salt solution and precipitant solution in parallel to the structure-inducing slurry, and maintain the pH of the reaction system at 8.90±0.03. When the solid content of the reaction system reaches 408 g / L, transfer a portion of the slurry from the reactor and add water to dilute it to 90% of the reactor volume. At this point, the solid content of the reaction system is 300 g / L. Continue the reaction until Dv50 reaches 5.9 μm and stop the liquid feeding to obtain a target slurry with qualified particle size and a solid content of 570.8 g / L. Unless otherwise specified, the inert gas flow rate, stirring speed, and temperature in steps 3-5 are the same as in step 2 (the same applies below). The color of the obtained target slurry with qualified particle size is quantitatively determined using a Lab colorimeter. The L value is 52.65, the a value is 6.19, and the b value is 19.13.

[0071] Step (6): The target slurry is placed in an aging tank, which is pre-purified with nitrogen. Under nitrogen purging, the material from the aging tank is washed with alkaline solution and pure water in a centrifuge, then centrifuged and dried before being transferred to an oven for drying. Under nitrogen purging, the material from the centrifuge is dried in an oven at 110°C for 20 hours. The material from the oven is then sieved and packaged to obtain the lithium-rich manganese-based precursor powder product. The electron microscope image is shown below. Figure 1 As shown, its molecular formula is Mn 0.65 Ni 0.35 (OH)2. The nitrogen flow rate during this step is 30 L / min.

[0072] Example 2 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material precursor, the specific steps of which are as follows: Step (1): Prepare the base solution by adding sodium hydroxide solution to a reactor containing water and adjusting the pH of the base solution to 10.38. The reactor used has a volume of 600L and is equipped with a concentrator for solidification. The base solution accounts for 90% of the volume of the reactor.

[0073] Step (2), nucleation stage: A mixed metal salt solution consisting of nickel sulfate crystals, manganese sulfate crystals, and water is prepared, with a nickel to manganese molar ratio of 35:65 and a total metal ion concentration of 112.5 g / L. The average flow rate of the mixed metal salt solution added per liter of reactor is 0.10 mol / h / L. The reactor temperature is maintained at 50℃, the stirring rate is 465 rpm, and the nitrogen flow rate per hour is 1.67% of the reactor volume. Simultaneously, a 10.8 mol / L sodium hydroxide solution is introduced to maintain the pH at 10.38 ± 0.03 for 90 min, resulting in a slurry.

[0074] Step (3), growth stage: under the condition that the flow rate of the mixed metal salt solution remains unchanged, the flow rate of the sodium hydroxide solution is reduced so that the pH gradually decreases to 9.10±0.03 at a rate of 0.025 / 30min. The mixed metal salt solution and precipitant solution are added in parallel and the pH of the reaction system is maintained at 9.10±0.03 until Dv50 reaches 3.5um, and the second-stage slurry is obtained.

[0075] Step (4): Increase the flow rate of sodium hydroxide solution to raise the pH by 1.0 within 3 min, and at the same time increase the flow rate of mixed metal salt solution added to the reactor to 0.133 mol / h / L. After 10 min, the structure-induced slurry is obtained.

[0076] Step (5): Reduce the flow rate of sodium hydroxide solution to restore the pH to 9.10±0.03. Maintain the flow rate of the mixed metal salt solution at 0.133 mol / h / L. Continue to add the mixed metal salt solution and precipitant solution in parallel to the structure-inducing slurry, and maintain the pH of the reaction system at 9.10±0.03. When the solid content of the reaction system reaches 500 g / L, transfer a portion of the slurry from the reactor and add water to dilute it to 90% of the reactor volume. At this point, the solid content of the reaction system is 150 g / L. Continue the reaction until the Dv50 reaches 6.2 μm and stop the liquid feeding to obtain a target slurry with qualified particle size and a solid content of 549.5 g / L. The color of the obtained target slurry with qualified particle size is quantitatively determined using a Lab colorimeter. The L value is 53.35, the a value is 4.32, and the b value is 19.41.

[0077] Step (6): The target slurry is placed in an aging tank, which is pre-purified with nitrogen. Under nitrogen purging, the material from the aging tank is washed with alkaline solution and pure water in a centrifuge, then centrifuged and dried before being transferred to an oven for drying. Under nitrogen purging, the material from the centrifuge is dried in an oven at 110°C for 20 hours. The material from the oven is then sieved and packaged to obtain the lithium-rich manganese-based precursor powder product. The electron microscope image is shown below. Figure 2 As shown, its molecular formula is Mn 0.65 Ni 0.35 (OH)2. The nitrogen flow rate during this step is 30 L / min.

[0078] Example 3 This embodiment provides a method for preparing a lithium-rich manganese-based cathode material precursor, the specific steps of which are as follows: Step (1): Prepare the base solution by adding sodium hydroxide solution to a reactor containing water and adjusting the pH of the base solution to 10.68. The reactor used has a volume of 600L and is equipped with a concentrator for solidification. The base solution accounts for 90% of the volume of the reactor.

[0079] Step (2), nucleation stage: A mixed metal salt solution consisting of nickel sulfate crystals, manganese sulfate crystals, and water is prepared, with a nickel to manganese molar ratio of 35:65 and a total metal ion concentration of 112.5 g / L. The average flow rate of the mixed metal salt solution added per liter of reactor is 0.10 mol / h / L. The reactor temperature is maintained at 50℃, the stirring rate is 465 rpm, and the nitrogen gas flow rate per hour is 2.5% of the reactor volume. Simultaneously, a 10.8 mol / L sodium hydroxide solution is introduced to maintain the pH at 10.34 ± 0.03 for 90 min, resulting in a slurry.

[0080] Step (3), growth stage: under the condition that the flow rate of the mixed metal salt solution remains unchanged, the flow rate of the sodium hydroxide solution is reduced so that the pH gradually decreases to 8.90±0.03 at a rate of 0.025 / 30min. The mixed metal salt solution and precipitant solution are added in parallel and the pH of the reaction system is maintained at 8.90±0.03 until Dv50 reaches 3.8um, and the second-stage slurry is obtained.

[0081] Step (4): Increase the flow rate of sodium hydroxide solution to raise the pH by 1.0 within 3 min, and at the same time increase the flow rate of mixed metal salt solution added to the reactor to 0.150 mol / h / L. After 30 min, the structure-induced slurry is obtained.

[0082] Step (5): Reduce the flow rate of sodium hydroxide solution to restore the pH to 8.90±0.03. Maintain the flow rate of the mixed metal salt solution at 0.150 mol / h / L. Continue to add the mixed metal salt solution and precipitant solution in parallel to the structure-inducing slurry, maintaining the pH of the reaction system at 8.90±0.03. When the solid content of the reaction system reaches 480 g / L, transfer a portion of the slurry from the reactor and dilute it with water in a container until the slurry volume accounts for 90% of the reactor volume. At this point, the solid content of the reaction system is 150 g / L. Continue the reaction until the Dv50 reaches 6.5 μm and then stop the liquid feeding to obtain a target slurry with qualified particle size and a solid content of 652.0 g / L. The color of the obtained target slurry with qualified particle size is quantitatively determined using a Lab colorimeter. The L value is 59.45, the a value is 2.56, and the b value is 21.73.

[0083] Step (6): The target slurry is placed in an aging tank, which is pre-purified with nitrogen. Under nitrogen purging, the material from the aging tank is washed with alkaline solution and pure water in a centrifuge, then centrifuged and dried before being transferred to an oven for drying. Under nitrogen purging, the material from the centrifuge is dried in an oven at 110°C for 20 hours. The material from the oven is then sieved and packaged to obtain the lithium-rich manganese-based precursor powder product. The electron microscope image is shown below. Figure 3 As shown, its molecular formula is Mn 0.65 Ni 0.35 (OH)2. The nitrogen flow rate during this step is 30 L / min.

[0084] Comparative Example 1 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material precursor. The only difference from Example 1 is that in step (5), the reaction continues until the Dv50 reaches 6.4 μm, at which point the liquid feeding is stopped to obtain a slurry with qualified particle size; in step (6), nitrogen gas is not introduced during the aging, washing, and drying processes. The electron micrograph of the prepared lithium-rich manganese-based cathode material precursor is shown below. Figure 4 As shown.

[0085] Comparative Example 2 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material precursor, which differs from Example 1 only in that: nitrogen is not introduced in steps (1)-(3), and the ratio of nitrogen flow rate per hour to reactor volume in steps (4) and (5) is 1.67%; the target slurry Dv50 is 6.3 μm, and the electron micrograph of the prepared lithium-rich manganese-based cathode material precursor is shown below. Figure 5 As shown.

[0086] Comparative Example 3 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material precursor. The only difference from Example 1 is that step (5) is omitted, and in step (4), while increasing the flow rate of the sodium hydroxide solution, ammonia is added to the system as a reaction complexing agent to maintain the ammonia concentration in the system at around 0.75 g / L; the addition of ammonia is stopped until Dv50 reaches 6.4 μm, and the target slurry is obtained. The electron micrograph of the prepared lithium-rich manganese-based cathode material precursor is shown below. Figure 6 As shown.

[0087] Comparative Example 4 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material precursor, which differs from Example 1 only in that the pH is maintained at 8.90±0.03 throughout step (4). The electron micrograph of the prepared lithium-rich manganese-based cathode material precursor is shown below. Figure 7 As shown.

[0088] Example 4 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material precursor. The only difference from Example 1 is that the flow rate of the mixed metal salt solution in steps (4)-(5) is always maintained at 0.16 mol / h / L. The electron micrograph of the prepared lithium-rich manganese-based cathode material precursor is shown in Figure 1. Figure 8 As shown.

[0089] Comparative Example 5 This comparative example provides a method for preparing a lithium-rich manganese-based cathode material precursor. The only difference from Example 1 is that the pH increase rate in step (4) is too slow. Increasing the flow rate of the sodium hydroxide solution will increase the pH by 1.0 within 30 minutes. The electron micrograph of the prepared lithium-rich manganese-based cathode material precursor is shown below. Figure 9 As shown.

[0090] The Dv50, diameter, specific surface area, tap density, porosity, average thickness and length of the primary lamellar particles, average thickness and length of the internal lamellars, the ratio of the area of ​​the internal lamellars to the cross-sectional area, and the sphericity and aspect ratio of the secondary particles of the lithium-rich manganese-based cathode precursors prepared in each embodiment and comparative example of this application were detected and calculated. The results are shown in Table 1 below.

[0091] Among them, Dv50, Dv90, and Dv10 were tested using a Malvern laser particle size analyzer and the radial distance was calculated based on (Dv90-Dv10) / Dv50. Tap density was tested using a Dandong Baite tap density meter; Specific surface area was measured using a Bestar nitrogen adsorption specific surface area meter; Porosity, sphericity and aspect ratio of secondary particles, average thickness and length of primary and secondary particles, and the ratio of the area of ​​internal laths to the cross-sectional area were measured and tested using graphic measurement software and length measurement software on electron micrographs. Among them, the number of test samples for sphericity and aspect ratio of secondary particles, and average thickness and length of primary and secondary particles were ≥10. Electron microscopy and cross-sectional electron microscopy were performed using Thermo Fisher Scientific's high-resolution field emission scanning electron microscope.

[0092] Table 1

[0093] This application employs a multi-stage dynamic pH control process, applying precise pH pulses (instantaneous increases of 0.3 to 1.0) during the mid-stage of particle growth (Dv50 of 2.0~4.0 μm), and synergistically increasing the feed flow rates of metal salt and precipitant, thus disrupting the pH-stable growth equilibrium during conventional co-precipitation. These pulses generate instantaneous localized supersaturation within the reaction system, selectively activating the edges or defect sites of the already formed lamellar primary particles, inducing their one-dimensional preferential rapid growth. Due to the constraints of surrounding particles and space, this growth is confined to a lamellar morphology and in situ interpenetrates within the secondary particles, forming a three-dimensional reinforced framework structure.

[0094] The slatted structure and the continuously growing thin sheet-like structure on the surface achieve functional division: the surface sheets provide a high specific surface area, enhance the solid-phase reaction activity with the lithium source, and improve the specific capacity of the cathode material after sintering; the internal slats serve as a mechanical support skeleton, significantly improving the tap density (up to 1.3~1.7 g / cm³) and mechanical strength of the precursor, giving the secondary particles excellent resistance to compressive and cyclic stress, effectively suppressing structural cracking and pulverization during long-term charge and discharge, and extending the battery cycle life.

[0095] In summary, this invention achieves precise construction of the internal microstructure of the precursor through a mechanism of "pH pulse induction + space-constrained growth" without the use of complexing agents. It solves the technical bottleneck of lithium-rich manganese-based materials in achieving both high capacity and long cycling, and has outstanding innovation and industrialization value.

[0096] The capacity and first-efficiency performance of the materials in the above examples and comparative examples were studied using coin half-cells. The experimental method is as follows: First, the positive electrode material was prepared by mechanically mixing lithium-rich manganese-based positive electrode material precursor and lithium hydroxide at a molar ratio of metal element to lithium element of 1:1.05, and sintering in a muffle furnace at 900℃ for 20 hours to obtain lithium-rich manganese-based positive electrode material. Next, coin half-cells were prepared. Positive electrode: The positive electrode material, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were stirred and dispersed with solvent NMP at a mass ratio of 92.5:5:2.5, coated on an aluminum foil substrate, and rolled to obtain the positive electrode. Negative electrode: Lithium sheet. Electrolyte: 1 mol / L LiPF6 solution, with a mixed solvent of EC and DMC in a volume ratio of 1:2. The charging cutoff voltage was 4.52V, and the discharging cutoff voltage was 2.3V. Cyclic performance was tested using a full-cell battery, with a charge cut-off voltage of 4.45V, a discharge cut-off voltage of 3.0V, a test temperature of 25℃, and a current of 0.33C. The test results are shown in Table 2.

[0097] Table 2

[0098] Regarding capacity enhancement, this application significantly increases the specific surface area by constructing thin, sheet-like primary particles (average thickness 20-80 nm), thereby enhancing the solid-state reaction contact area and diffusion efficiency between the precursor and lithium source during high-temperature sintering, promoting the formation of a highly active lithium-rich phase, and thus improving the specific capacity of the cathode material. Simultaneously, nitrogen is continuously introduced during post-processing steps such as aging, washing, and drying to maintain an inert protective atmosphere, effectively suppressing the formation of impurities such as divalent manganese oxidation and basic manganese compounds, ensuring material purity, and avoiding capacity decay caused by byproducts.

[0099] Regarding structural stability and high compaction, the high sphericity (0.8~0.9) secondary particles of this application possess excellent packing performance and powder flowability. Combined with the internally interspersed lath-shaped primary particles (average thickness 110~150 nm, area ratio 30%~80%), a three-dimensional reinforced framework structure is formed, significantly improving the mechanical strength and tap density (1.3~1.7 g / cm³) of the precursor. This structure can achieve higher compaction density during electrode rolling and effectively buffers volumetric strain during cycling, suppressing microcrack formation and particle pulverization, and significantly extending battery cycle life.

[0100] In terms of performance balance, this application achieves synergistic optimization of "high reactivity" and "high structural stability" by precisely controlling key parameters such as Dv50 (5.0~7.0 μm), porosity (3.0%~6.0%), diameter spacing, and specific surface area. This solves the core industrialization problem of lithium-rich manganese-based materials, which is difficult to balance high energy density and long lifespan, and has important application value.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lithium-rich manganese-based cathode material precursor, characterized in that, The secondary particles comprise primary particles, the primary particles including sheet-like primary particles and slat-like primary particles, the sheet-like primary particles having an average thickness of 20~80nm and an average length of 100~500nm; the slat-like primary particles are located inside the lithium-rich manganese-based cathode material precursor, the slat-like primary particles having an average thickness of 110nm~150nm and an average length of 800nm~1200nm.

2. The lithium-rich manganese-based cathode material precursor according to claim 1, characterized in that, The secondary particles consist of a core, a middle layer, and a surface layer from the inside out, and the porosity of the core and the surface layer is less than that of the middle layer. And / or, the secondary particles comprise, from the inside out, a core, a middle layer, and a surface layer, wherein the average pore size of the core and the surface layer is smaller than the average pore size of the middle layer; And / or, the secondary particles consist of a core, a middle layer and a surface layer from the inside out, and the lath-shaped primary particles are mainly distributed in the middle layer; And / or, in the cross-section of the secondary particles, the area of ​​the lath-shaped primary particles accounts for 30% to 80% of the total cross-sectional area.

3. The lithium-rich manganese-based cathode material precursor according to claim 1, characterized in that, The sphericity of the secondary particles is 0.8~0.9; And / or, the precursor of the lithium-rich manganese-based cathode material has the molecular formula Mn. x Ni 1-x (OH)₂, where 0.5 ≤ x ≤ 0.8; And / or, the Dv50 of the lithium-rich manganese-based cathode material precursor is 5.0~7.0 μm; And / or, the porosity of the lithium-rich manganese-based cathode material precursor is 3.0%~6.0%; And / or, the radial distance of the lithium-rich manganese-based cathode material precursor is 0.3~0.4; And / or, the specific surface area of ​​the lithium-rich manganese-based cathode material precursor is 22~36 m². 2 / g; And / or, the average aspect ratio of the secondary particles is 1.1 to 1.2; And / or, the tap density of the lithium-rich manganese-based cathode material precursor is 1.3~1.7 g / cm³. 3 .

4. A method for preparing a lithium-rich manganese-based cathode material precursor according to any one of claims 1-3, characterized in that, include: During the nucleation stage, under a protective atmosphere and stirring conditions, a mixed metal salt solution and a precipitant solution are added concurrently to the bottom liquid containing the precipitant, and the pH of the reaction system is maintained at 10.0~11.0 to obtain a slurry. During the growth stage, under a protective atmosphere and stirring conditions, the mixed metal salt solution was continuously added, and the flow rate of the precipitant solution was gradually reduced so that the pH of the reaction system gradually decreased to 8.67~9.

33. The pH was maintained at 8.67~9.33 until the Dv50 reached 2.0~4.0um, thus obtaining the second-stage slurry. Structure-induced slurry containing lath-shaped primary particles was obtained by increasing the flow rate of the mixed metal salt solution and precipitant under a protective atmosphere and stirring conditions. This resulted in a pH increase of 0.3 to 1.0 in the reaction system compared to the two-stage slurry within 1 to 10 minutes. Continue growth, and under a protective atmosphere and stirring conditions, continue to add mixed metal salt solution to the structure-inducing slurry while reducing the flow rate of the precipitant solution to maintain the pH of the reaction system at 8.67~9.33, to obtain the target slurry; In the post-processing stage, the target slurry is sequentially aged, washed, and dried under a protective atmosphere to obtain the lithium-rich manganese-based cathode material precursor.

5. The method for preparing the lithium-rich manganese-based cathode material precursor according to claim 4, characterized in that, The mixed metal salt solution includes nickel ions and manganese ions, and the molar ratio of nickel to manganese is (1-x):x, 0.5≤x≤0.8; And / or, the total concentration of metal ions in the mixed metal salt solution is 100 g / L to 120 g / L; And / or, the precipitant is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, and lithium hydroxide; And / or, the pH of the substrate solution is 10.10~10.70; And / or, the bottom liquid accounts for 80% to 95% of the volume of the reactor in which it is located.

6. The method for preparing the lithium-rich manganese-based cathode material precursor according to claim 4, characterized in that, During the nucleation and growth stages, the flow rate of the mixed metal salt solution is 0.097 mol / h / L. 反应器 ~0.103 mol / h / L 反应器 ; And / or, the stirring speed is 450 rpm to 550 rpm; And / or, the nucleation time is 30 min to 120 min.

7. The method for preparing the lithium-rich manganese-based cathode material precursor according to claim 4, characterized in that, During the nucleation stage, growth stage, structure induction, and continued growth steps, a protective gas is introduced into the reactor at a rate of 1% to 3% of the reactor volume per hour. And / or, the post-processing step introduces protective gas into the equipment, and the amount of protective gas introduced per hour is 1% to 5% of the equipment volume.

8. The method for preparing the lithium-rich manganese-based cathode material precursor according to claim 4, characterized in that, The time for the structure induction step is 1~60 min; And / or, the rate of pH decrease during the growth phase is 0.02 / 30min to 0.06 / 30min; And / or, the pH of the structure-inducing step is lower than the pH of the nucleation stage; And / or, in the structure induction step and the continued growth step, the flow rate of the mixed metal salt solution is 0.133 mol / h / L. 反应器 ~0.183 mol / h / L 反应器 .

9. The method for preparing the lithium-rich manganese-based cathode material precursor according to claim 4, characterized in that, In the continued growth step, when the solid content of the reaction system reaches 400~500g / L for the first time, the solid content is adjusted to 150g / L~300g / L, and then the co-precipitation step is continued. And / or, the solid content of the target slurry is 550 g / L to 750 g / L; And / or, use a Lab colorimeter to test the color of the target slurry, with an L value of 50-60, an a value of 2-7, and a b value of 19-24.

10. A lithium-rich manganese-based cathode material, characterized in that, The raw materials include the lithium-rich manganese-based cathode material precursor as described in any one of claims 1-3.

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