A large-particle nickel-cobalt-manganese ternary precursor, a preparation method and application thereof

Abstract

The application provides a large-particle nickel-cobalt-manganese ternary precursor, a preparation method and application thereof. The preparation method comprises the following steps: adding a first nickel-cobalt-manganese mixed salt solution, a first precipitant solution and a first complexing agent solution into a first bottom solution, performing a nucleation stage co-precipitation reaction to obtain a nickel-cobalt-manganese ternary precursor seed slurry; the nucleation stage co-precipitation reaction satisfies C1=A1x pH1-7.9; taking the nickel-cobalt-manganese ternary precursor seed slurry as a second bottom solution, adding a second nickel-cobalt-manganese mixed salt solution, a second precipitant solution and a second complexing agent solution into the second bottom solution, performing a growth stage co-precipitation reaction to obtain a large-particle nickel-cobalt-manganese ternary precursor; the growth stage co-precipitation reaction satisfies C2=A2x pH2-18.9; |A1|<|A2|. The preparation method provided by the application can stably prepare a nickel-cobalt-manganese ternary precursor with a large particle size, a narrow particle size distribution, a low specific surface area and a high tap density.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a large-particle nickel-cobalt-manganese ternary precursor, its preparation method, and its application. Background Technology

[0002] Ternary lithium-ion batteries are widely used in the new energy field due to their advantages such as high energy density, good low-temperature performance, good cycle performance, and high charge-discharge efficiency. The performance of ternary lithium-ion batteries is closely related to the ternary cathode material, which is usually formed by sintering a ternary cathode material precursor with a lithium salt. Therefore, the physicochemical properties of the ternary cathode material precursor fundamentally determine the structural stability, processing performance, and electrochemical performance of the final cathode material.

[0003] Coprecipitation is the mainstream process for preparing nickel-cobalt-manganese ternary precursors. Its core lies in the precise control of parameters such as pH, complexing agent concentration, and temperature in the reaction system to achieve active control over particle nucleation, growth, and morphology. In existing research, to prepare large-particle nickel-cobalt-manganese ternary precursors, researchers typically employ methods such as staged adjustment of pH and complexing agent concentration, setting multi-stage reaction conditions, or introducing post-processing modifications. While these methods can control the size and morphology of precursor particles to some extent, they struggle to simultaneously achieve multiple key indicators such as narrow particle size distribution, low specific surface area, and high tap density, and these properties often exhibit trade-offs.

[0004] Therefore, how to stably prepare nickel-cobalt-manganese ternary precursors that combine large particle size, narrow distribution, low specific surface area, and high tap density is an urgent technical problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a large-particle nickel-cobalt-manganese ternary precursor, its preparation method, and its applications. In the nucleation and growth stages of the co-precipitation reaction, the present invention establishes quantitative relationships with different slopes between pH value and complexing agent concentration in different reaction systems. This control strategy not only ensures the rapid formation of a large number of uniform and dense crystal nuclei during the nucleation stage but also effectively buffers ion concentration and stabilizes the reaction environment during the growth stage, thereby inhibiting secondary nucleation and abnormal growth and improving growth quality. Based on this, a nickel-cobalt-manganese ternary precursor with large particle size, narrow particle size distribution, low specific surface area, and high tap density can be stably prepared, laying the foundation for the subsequent preparation of high-performance ternary cathode materials.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a large-particle nickel-cobalt-manganese ternary precursor, the method comprising the following steps: The first nickel-cobalt-manganese mixed salt solution, the first precipitant solution, and the first complexing agent solution are added to the first base solution to carry out a co-precipitation reaction in the nucleation stage, thereby obtaining a nickel-cobalt-manganese ternary precursor seed slurry.

[0007] Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of the first complexing agent in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage.

[0008] Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, a second precipitant solution, and a second complexing agent solution are added to the second base liquid to carry out a co-precipitation reaction during the growth stage, thereby obtaining the large-particle nickel-cobalt-manganese ternary precursor.

[0009] Wherein, the coprecipitation reaction in the growth stage satisfies: C2 = A2 × pH2 - 18.9, where C2 is the concentration of the second complexing agent in the coprecipitation reaction in the growth stage, in mol / L, and pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage.

[0010] Where |A1| < |A2|.

[0011] In the nucleation and growth stages of the coprecipitation reaction, this invention establishes quantitative relationships with different slopes between pH value and complexing agent concentration in different reaction systems. This control strategy not only ensures the rapid formation of a large number of uniform and dense crystal nuclei during the nucleation stage, but also effectively buffers ion concentration and stabilizes the reaction environment during the growth stage, thereby inhibiting secondary nucleation and abnormal growth and improving growth quality. Based on this, it is possible to stably prepare nickel-cobalt-manganese ternary precursors with large particle size, narrow particle size distribution, low specific surface area, and high tap density, laying the foundation for the subsequent preparation of high-performance ternary cathode materials.

[0012] In this invention, |A1| < |A2|. On the one hand, this relationship facilitates the acquisition of uniform and dense crystal nuclei with relatively gentle coupling changes during the nucleation stage, avoiding low nucleation efficiency or crystal agglomeration due to excessive complexing agent response. On the other hand, this relationship kinetically limits the sensitivity of the complexing agent concentration to pH changes during the growth stage. This specific design allows the pH value of the reaction system during the growth stage to be rapidly "buffered" and "compensated" by a greater degree of complexing agent concentration change, thereby maintaining the supersaturation of the reaction interface within a suitable range. This effectively suppresses secondary nucleation caused by excessively high local supersaturation and poor morphology quality caused by unstable ion release rates, ensuring that the particles grow continuously in a dense and uniform manner.

[0013] Preferably, A1 is 0.75-0.85, for example, it can be 0.75, 0.8 or 0.85, etc.

[0014] In this invention, when A1 is 0.75-0.85, the concentration of the complexing agent during the nucleation stage is adjusted gradually with pH changes. This ensures that while providing complexation to prevent aggregation, it also guarantees the OH group's saturation. - Concentration (reflected by pH) is always the dominant driving force, thus obtaining seed crystals with uniform size and dense structure.

[0015] Preferably, A2 is 1.9-2.1, for example, it can be 1.9, 2 or 2.1, etc.

[0016] In this invention, A2 is 1.9-2.1, so the concentration of the complexing agent during the growth stage is extremely sensitive to pH changes. This design gives the reaction system a strong "buffering" capacity, which can quickly convert minor fluctuations in pH into significant adjustments in the concentration of the complexing agent, thereby effectively buffering ion concentration, stabilizing the reaction environment, inhibiting secondary nucleation and abnormal growth, and improving growth quality.

[0017] Preferably, the pH1 is 10.5-11, for example, it can be 10.5, 10.6, 10.7, 10.8, 10.9 or 11.

[0018] In this invention, pH 1 is 10.5-11, and this pH range ensures sufficient OH- ions during the nucleation stage. - Concentration and reaction driving force are conducive to the rapid initiation of homogeneous nucleation and provide a high-quality seed base for subsequent growth.

[0019] Preferably, the pH2 is 10-10.5, for example, it can be 10, 10.1, 10.2, 10.3, 10.4 or 10.5, etc.

[0020] In this invention, pH 2 is 10-10.5. This pH range effectively inhibits new homogeneous nucleation. Combined with the higher A2 value at this stage, it ensures that the particles can grow continuously and uniformly under controlled and stable conditions, ultimately achieving synergistic optimization of particle size, morphology and density.

[0021] Preferably, the first complexing agent solution and the second complexing agent solution each independently comprise ammonia.

[0022] Preferably, in the nickel-cobalt-manganese ternary precursor seed slurry, the particle size D50 of the seed particles is 2-4 μm, for example, it can be 2 μm, 3 μm or 4 μm, etc.

[0023] Preferably, in the coprecipitation reaction of the nucleation stage, the reaction temperature is 50-60℃, for example, 50℃, 55℃ or 60℃.

[0024] Preferably, the reaction temperature in the coprecipitation reaction during the growth stage is 55-65℃, for example, 55℃, 60℃ or 65℃.

[0025] Preferably, the reaction time in the coprecipitation reaction during the growth stage is 20-60 hours, for example, 20 hours, 30 hours, 40 hours, 50 hours, or 60 hours.

[0026] Preferably, the total concentration of metal salts in the first nickel-cobalt-manganese mixed salt solution and the second nickel-cobalt-manganese mixed salt solution is independently 1-5 mol / L, for example, it can be 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, etc.

[0027] For example, the first nickel-cobalt-manganese mixed salt solution and the second nickel-cobalt-manganese mixed salt solution can be sulfate solutions, etc.

[0028] Preferably, after the co-precipitation reaction of the growth stage, aging, filtration, washing and drying are also carried out.

[0029] Preferably, the preparation method includes the following steps: (1) Based on the general chemical formula Ni x Co y Mn 1-x-y (OH)2 is used to prepare a first nickel-cobalt-manganese mixed salt solution and a second nickel-cobalt-manganese mixed salt solution with a concentration of 1-5 mol / L, wherein 0.8≤x<1 (e.g., it can be 0.8, 0.85, 0.9 or 0.95, etc.) and 0.05≤y<0.2 ​​(e.g., it can be 0.05, 0.1 or 0.15, etc.).

[0030] (2) Add water, alkali and ammonia to the reactor to obtain a first bottom liquid with a pH of 10.5-11 (e.g., 10.5, 10.6, 10.7, 10.8, 10.9 or 11, etc.), and introduce an inert gas (e.g., nitrogen or argon, etc.) as a protective gas.

[0031] (3) Add the first nickel-cobalt-manganese mixed salt solution, alkaline solution and ammonia water to the first base liquid to carry out the co-precipitation reaction in the nucleation stage. The reaction temperature is 50-60℃. Stop feeding when the particle size D50 of the seed crystal is 2-4μm to obtain nickel-cobalt-manganese ternary precursor seed crystal slurry.

[0032] Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of ammonia in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage; A1 is 0.75-0.85; pH1 is 10.5-11; and C1 is 0.5-1 mol / L (for example, it can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1 mol / L, etc.).

[0033] (4) Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, alkali solution and ammonia water are added to the second base liquid to carry out a co-precipitation reaction in the growth stage. The reaction temperature is 55-65℃ and the reaction time is 20-60h. After the reaction is completed, the precursor is aged, filtered, washed and dried to obtain large-particle nickel-cobalt-manganese ternary precursor.

[0034] Wherein, the coprecipitation reaction in the growth stage satisfies: C2 = A2 × pH2 - 18.9, where C2 is the concentration of ammonia in the coprecipitation reaction in the growth stage, in mol / L, and pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage; A2 is 1.9-2.1; pH2 is 10-10.5; and C2 is 1.1-2.1 mol / L (for example, it can be 1.1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, or 2.1 mol / L, etc.).

[0035] In a second aspect, the present invention provides a large-particle nickel-cobalt-manganese ternary precursor, which is prepared by the preparation method described in the first aspect.

[0036] Preferably, the particle size distribution of the large-particle nickel-cobalt-manganese ternary precursor is Span≤0.8, for example, it can be 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2 or 0.1, etc.

[0037] It should be noted that the particle size distribution Span = (D90 - D10) / D50.

[0038] Preferably, the specific surface area of ​​the large-particle nickel-cobalt-manganese ternary precursor is ≤6m². 2 / g, for example, could be 6m 2 / g, 5.5m 2 / g、5m 2 / g, 4.5m 2 / g、4m 2 / g or 3m 2 / g etc.

[0039] Preferably, the tap density of the large-particle nickel-cobalt-manganese ternary precursor is ≥2 g / cm³. 3 For example, it could be 2g / cm 3 2.2g / cm 3 2.4g / cm 3 2.6g / cm 3 2.8g / cm 3 Or 3g / cm 3 wait.

[0040] Preferably, the particle size D50 of the large-particle nickel-cobalt-manganese ternary precursor is ≥12μm, for example, it can be 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm or 20μm, etc.

[0041] Thirdly, the present invention provides a nickel-cobalt-manganese ternary cathode material, wherein the nickel-cobalt-manganese ternary cathode material is obtained by mixing and sintering a large-particle nickel-cobalt-manganese ternary precursor as described in the second aspect with a lithium source.

[0042] For example, the lithium source can be lithium carbonate or lithium hydroxide.

[0043] Fourthly, the present invention provides a lithium-ion battery, wherein the positive electrode of the lithium-ion battery includes a nickel-cobalt-manganese ternary positive electrode material as described in the third aspect.

[0044] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0045] Compared with the prior art, the present invention has the following beneficial effects: In the nucleation and growth stages of the coprecipitation reaction, this invention establishes quantitative relationships with different slopes between pH value and complexing agent concentration in different reaction systems. This control strategy not only ensures the rapid formation of a large number of uniform and dense crystal nuclei during the nucleation stage, but also effectively buffers ion concentration and stabilizes the reaction environment during the growth stage, thereby inhibiting secondary nucleation and abnormal growth and improving growth quality. Based on this, it is possible to stably prepare nickel-cobalt-manganese ternary precursors with large particle size, narrow particle size distribution, low specific surface area, and high tap density, laying the foundation for the subsequent preparation of high-performance ternary cathode materials. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0047] Example 1 This embodiment provides a method for preparing a large-particle nickel-cobalt-manganese ternary precursor, the preparation method comprising the following steps: (1) Based on the general chemical formula Ni x Co y Mn 1-x-y (OH)2 was used to prepare a first nickel-cobalt-manganese mixed sulfate solution and a second nickel-cobalt-manganese mixed sulfate solution with a concentration of 3 mol / L, where x=0.8 and y=0.1.

[0048] (2) Add water, alkali solution and ammonia water to the reactor to obtain the first bottom liquid with pH 10.5, and introduce nitrogen gas as a protective gas.

[0049] (3) Add the first nickel-cobalt-manganese mixed salt solution, alkaline solution and ammonia water to the first base liquid to carry out the co-precipitation reaction in the nucleation stage. The reaction temperature is 55℃. Stop feeding when the particle size D50 of the seed crystal is 3μm to obtain nickel-cobalt-manganese ternary precursor seed crystal slurry.

[0050] Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of ammonia in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage; A1 is 0.8; pH1 is 10.8; and C1 is 0.75 mol / L.

[0051] (4) Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, alkali solution and ammonia water are added to the second base liquid to carry out the co-precipitation reaction in the growth stage. The reaction temperature is 50℃ and the reaction time is 40h. After the reaction is completed, the precursor is aged, filtered, washed and dried to obtain large-particle nickel-cobalt-manganese ternary precursor.

[0052] Wherein, the coprecipitation reaction in the growth stage satisfies: C2 = A2 × pH2 - 18.9, where C2 is the concentration of ammonia in the coprecipitation reaction in the growth stage, in mol / L, and pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage; A2 is 2; pH2 is 10.3, and C2 is 1.7 mol / L.

[0053] Example 2 This embodiment provides a method for preparing a large-particle nickel-cobalt-manganese ternary precursor, the preparation method comprising the following steps: (1) Based on the general chemical formula Ni x Co y Mn 1-x-y(OH)2 was used to prepare a first nickel-cobalt-manganese mixed sulfate solution and a second nickel-cobalt-manganese mixed sulfate solution with a concentration of 3 mol / L, where x=0.8 and y=0.1.

[0054] (2) Add water, alkali solution and ammonia water to the reactor to obtain the first bottom liquid with pH 10.5, and introduce nitrogen gas as a protective gas.

[0055] (3) Add the first nickel-cobalt-manganese mixed salt solution, alkaline solution and ammonia water to the first base liquid to carry out the co-precipitation reaction in the nucleation stage. The reaction temperature is 50℃. Stop feeding when the particle size D50 of the seed crystal is 2μm to obtain nickel-cobalt-manganese ternary precursor seed crystal slurry.

[0056] Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of ammonia in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage; A1 is 0.8; pH1 is 10.5; and C1 is 0.5 mol / L.

[0057] (4) Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, alkali solution and ammonia water are added to the second base liquid to carry out the co-precipitation reaction in the growth stage. The reaction temperature is 55℃ and the reaction time is 45h. After the reaction is completed, the precursor is aged, filtered, washed and dried to obtain large-particle nickel-cobalt-manganese ternary precursor.

[0058] Wherein, the coprecipitation reaction in the growth stage satisfies: C2 = A2 × pH2 - 18.9, where C2 is the concentration of ammonia in the coprecipitation reaction in the growth stage, in mol / L, pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage; A2 is 2; pH2 is 10; and C2 is 1.1 mol / L.

[0059] Example 3 This embodiment provides a method for preparing a large-particle nickel-cobalt-manganese ternary precursor, the preparation method comprising the following steps: (1) Based on the general chemical formula Ni x Co y Mn 1-x-y (OH)2 was used to prepare a first nickel-cobalt-manganese mixed sulfate solution and a second nickel-cobalt-manganese mixed sulfate solution with a concentration of 3 mol / L, where x=0.8 and y=0.1.

[0060] (2) Add water, alkali solution and ammonia water to the reactor to obtain the first bottom liquid with pH 10.5, and introduce nitrogen gas as a protective gas.

[0061] (3) Add the first nickel-cobalt-manganese mixed salt solution, alkaline solution and ammonia water to the first base liquid to carry out the co-precipitation reaction in the nucleation stage. The reaction temperature is 60℃. Stop feeding when the particle size D50 of the seed crystal is 4μm to obtain nickel-cobalt-manganese ternary precursor seed crystal slurry.

[0062] Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of ammonia in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage; A1 is 0.8; pH1 is 11; and C1 is 0.9 mol / L.

[0063] (4) Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, alkali solution and ammonia water are added to the second base liquid to carry out the co-precipitation reaction in the growth stage. The reaction temperature is 65℃ and the reaction time is 35h. After the reaction is completed, the precursor is aged, filtered, washed and dried to obtain large-particle nickel-cobalt-manganese ternary precursor.

[0064] Wherein, the coprecipitation reaction in the growth stage satisfies: C2 = A2 × pH2 - 18.9, where C2 is the concentration of ammonia in the coprecipitation reaction in the growth stage, in mol / L, pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage; A2 is 2; pH2 is 10.5, and C2 is 2.1 mol / L.

[0065] Example 4 The difference between this embodiment and Embodiment 1 is that A1 is 0.7.

[0066] The remaining preparation methods and parameters are consistent with those in Example 1.

[0067] Example 5 The difference between this embodiment and Embodiment 1 is that A1 is 0.9.

[0068] The remaining preparation methods and parameters are consistent with those in Example 1.

[0069] Example 6 The difference between this embodiment and Embodiment 1 is that A2 is 1.7.

[0070] The remaining preparation methods and parameters are consistent with those in Example 1.

[0071] Example 7 The difference between this embodiment and Embodiment 1 is that A2 is 2.3.

[0072] The remaining preparation methods and parameters are consistent with those in Example 1.

[0073] Comparative Example 1 The difference between this comparative example and Example 1 is that, in the coprecipitation reaction of the nucleation stage, the pH of the reaction system and the concentration of ammonia water do not satisfy the relationship C1=0.8×pH1-7.9.

[0074] The remaining preparation methods and parameters are consistent with those in Example 1.

[0075] Comparative Example 2 The difference between this comparative example and Example 1 is that, in the coprecipitation reaction during the growth stage, the pH of the reaction system and the concentration of ammonia water do not satisfy the relationship C2=2×pH2-18.9.

[0076] The remaining preparation methods and parameters are consistent with those in Example 1.

[0077] Performance testing 1. The particle size D50 and particle size distribution Span of the large-particle nickel-cobalt-manganese ternary precursors provided in the above embodiments and comparative examples were tested by laser diffraction particle size analysis method; the specific surface area was tested by BET method; and the tap density was tested according to the national standard GB / T21354-2008.

[0078] 2. The large-particle nickel-cobalt-manganese ternary precursors provided in the above examples and comparative examples are mixed and sintered with lithium carbonate (pre-fired at 500°C for 3 hours, and then sintered at 800°C for 15 hours) to obtain nickel-cobalt-manganese ternary cathode materials.

[0079] Preparation of coin cells: The above-mentioned nickel-cobalt-manganese ternary cathode material, acetylene black and polyvinylidene fluoride were uniformly mixed in N-methylpyrrolidone at a mass ratio of 90:5:5, and then coated on aluminum foil. The mixture was then dried in a vacuum drying oven. After drying, the cathode was pressed into a positive electrode sheet using a tablet press in an argon glove box. In the glove box, the positive electrode sheet, polypropylene porous separator, negative lithium sheet and electrolyte were assembled into a coin cell. The solute in the electrolyte was LiPF6 with a concentration of 1 mol / L, and the solvent was EC (ethylene carbonate) and DMC (dimethyl carbonate) in a volume ratio of 1:1.

[0080] The coin cell was subjected to constant current charge-discharge tests to test the capacity performance and cycle stability of the ternary cathode material. The test voltage was 2.8V-4.3V, and the results are shown in Table 1.

[0081] Table 1 analyze: As shown in Table 1, this invention establishes quantitative relationships with different slopes between pH value and complexing agent concentration in different reaction systems during the nucleation and growth stages of the coprecipitation reaction. This control strategy not only ensures the rapid formation of a large number of uniform and dense crystal nuclei during the nucleation stage, but also effectively buffers ion concentration and stabilizes the reaction environment during the growth stage, thereby inhibiting secondary nucleation and abnormal growth and improving growth quality. Based on this, it is possible to stably prepare crystals with a particle size D50 ≥12μm, a particle size distribution Span ≤0.8, and a specific surface area ≤6m². 2 / g and tap density ≥2g / cm³ 3 The nickel-cobalt-manganese ternary precursors laid the foundation for the subsequent preparation of high-performance ternary cathode materials.

[0082] As can be seen from the comparison between Example 1 and Examples 4-5, if A1 is too small, the response speed of the complexing agent concentration in the nucleation stage is insufficient, resulting in a decrease in the crystal nucleus generation rate and uniformity, which affects the subsequent growth basis; if A1 is too large, the effect of the complexing agent in the nucleation stage is too strong, which may excessively inhibit nucleation or cause crystal nucleus agglomeration, affecting the quality of the seed crystal.

[0083] As can be seen from the comparison between Example 1 and Examples 6-7, if A2 is too small, the buffering capacity of the complexing agent in the growth stage is insufficient, and it cannot effectively stabilize the reaction interface, making it easy for secondary nucleation and surface defects to occur; if A2 is too large, it may lead to the inhibition of growth rate or the imbalance of reaction system stability, which is not conducive to the continuous dense growth of particles.

[0084] As can be seen from the comparison between Example 1 and Comparative Example 1, if the pH and ammonia concentration of the reaction system do not satisfy the relationship C1=0.8×pH1-7.9 in the coprecipitation reaction of the nucleation stage, it is difficult to form high-quality seed crystals, resulting in poor subsequent growth quality, wider product particle size distribution, and a significant decrease in tap density.

[0085] As can be seen from the comparison between Example 1 and Comparative Example 2, if the pH and ammonia concentration of the reaction system do not satisfy the relationship C2=2×pH2-18.9 in the coprecipitation reaction during the growth stage, the growth control of the particles will be inaccurate, the particles will be difficult to maintain uniform epitaxial growth, and the overall performance will deteriorate.

[0086] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a large-particle nickel-cobalt-manganese ternary precursor, characterized in that, The preparation method includes the following steps: The first nickel-cobalt-manganese mixed salt solution, the first precipitant solution, and the first complexing agent solution are added to the first base solution to carry out a co-precipitation reaction in the nucleation stage, thereby obtaining a nickel-cobalt-manganese ternary precursor seed slurry. Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of the first complexing agent in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage; Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, a second precipitant solution, and a second complexing agent solution are added to the second base liquid to carry out a co-precipitation reaction in the growth stage, thereby obtaining the large-particle nickel-cobalt-manganese ternary precursor; Wherein, the coprecipitation reaction in the growth stage satisfies: C2=A2×pH2-18.9, where C2 is the concentration of the second complexing agent in the coprecipitation reaction in the growth stage, in mol / L, and pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage; Where |A1| < |A2|.

2. The preparation method according to claim 1, characterized in that, The value of A1 is 0.75-0.85; And / or, A2 is 1.9-2.

1.

3. The preparation method according to claim 1 or 2, characterized in that, The pH1 is 10.5-11; And / or, the pH2 is 10-10.

5.

4. The preparation method according to any one of claims 1-3, characterized in that, The first complexing agent solution and the second complexing agent solution each independently comprise ammonia water; And / or, in the nickel-cobalt-manganese ternary precursor seed slurry, the particle size D50 of the seed particles is 2-4 μm.

5. The preparation method according to any one of claims 1-4, characterized in that, In the coprecipitation reaction of the nucleation stage, the reaction temperature is 50-60℃; And / or, in the coprecipitation reaction of the growth stage, the reaction temperature is 55-65℃; And / or, in the coprecipitation reaction of the growth stage, the reaction time is 20-60 h.

6. The preparation method according to any one of claims 1-5, characterized in that, The total concentration of metal salts in the first nickel-cobalt-manganese mixed salt solution and the second nickel-cobalt-manganese mixed salt solution is independently 1-5 mol / L; And / or, after the co-precipitation reaction of the growth stage, aging, filtration, washing and drying are also carried out.

7. The preparation method according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Based on the general chemical formula Ni x Co y Mn 1-x-y (OH)2 was used to prepare a first nickel-cobalt-manganese mixed salt solution and a second nickel-cobalt-manganese mixed salt solution with a concentration of 1-5 mol / L, where 0.8 ≤ x < 1 and 0.05 ≤ y < 0.

2. (2) Add water, alkali solution and ammonia water to the reactor to obtain the first bottom liquid with a pH of 10.5-11, and introduce inert gas as a protective gas; (3) Add the first nickel-cobalt-manganese mixed salt solution, alkaline solution and ammonia water to the first base liquid to carry out the co-precipitation reaction in the nucleation stage. The reaction temperature is 50-60℃. Stop feeding when the particle size D50 of the seed crystal particles is 2-4μm to obtain nickel-cobalt-manganese ternary precursor seed crystal slurry. Wherein, the coprecipitation reaction in the nucleation stage satisfies: C1 = A1 × pH1 - 7.9, where C1 is the concentration of ammonia in the coprecipitation reaction in the nucleation stage, in mol / L, and pH1 is the pH of the reaction system during the coprecipitation reaction in the nucleation stage; A1 is 0.75-0.85; pH1 is 10.5-11; and C1 is 0.5-1 mol / L. (4) Using the nickel-cobalt-manganese ternary precursor seed slurry as the second base liquid, a second nickel-cobalt-manganese mixed salt solution, alkaline solution and ammonia water are added to the second base liquid to carry out the co-precipitation reaction in the growth stage. The reaction temperature is 55-65℃ and the reaction time is 20-60h. After the reaction is completed, the precursor is aged, filtered, washed and dried to obtain large-particle nickel-cobalt-manganese ternary precursor. Wherein, the coprecipitation reaction in the growth stage satisfies: C2 = A2 × pH2 - 18.9, where C2 is the concentration of ammonia in the coprecipitation reaction in the growth stage, in mol / L, and pH2 is the pH of the reaction system during the coprecipitation reaction in the growth stage; A2 is 1.9-2.1; pH2 is 10-10.5; and C2 is 1.1-2.1 mol / L.

8. A large-particle nickel-cobalt-manganese ternary precursor, characterized in that, The large-particle nickel-cobalt-manganese ternary precursor was prepared by the preparation method described in any one of claims 1-7; The particle size distribution of the large-particle nickel-cobalt-manganese ternary precursor is Span≤0.8; The specific surface area of ​​the large-particle nickel-cobalt-manganese ternary precursor is ≤6m². 2 / g; The tap density of the large-particle nickel-cobalt-manganese ternary precursor is ≥2g / cm³. 3 ; The particle size D50 of the large-particle nickel-cobalt-manganese ternary precursor is ≥12μm.

9. A nickel-cobalt-manganese ternary cathode material, characterized in that, The nickel-cobalt-manganese ternary cathode material is obtained by sintering a mixture of the large-particle nickel-cobalt-manganese ternary precursor as described in claim 8 and a lithium source.

10. A lithium-ion battery, characterized in that, The positive electrode of the lithium-ion battery includes the nickel-cobalt-manganese ternary positive electrode material as described in claim 9.

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