Preparation method of precursor seed crystal of multi-element positive electrode material with ultra-narrow particle size distribution

Abstract

The invention provides a preparation method of a precursor seed crystal of a multi-element positive electrode material with ultra-narrow particle size distribution, and the preparation method comprises the following three stages: in a seed crystal nucleation stage, in a plurality of small reaction kettles, generating manganese hydroxide seed crystal by accurately regulating and controlling the oxygen content, the pH value, the concentration of a nitrogen-containing complexing agent and the stirring speed; in the seed crystal aging stage, the seed crystal is transferred to a medium-sized reaction kettle, and the morphology is optimized under high-temperature and high-pH conditions; the seed crystal growth stage is carried out in a large-scale reaction kettle, and multiple parameters are regulated and controlled in a gradient manner to realize the staged growth of crystal grains. According to the preparation method, through multi-kettle segmented control and multi-parameter coordinated adjustment, the particle size distribution coefficient K ((D90-D10) / D50) of the prepared seed crystal is in an ultra-narrow range of 0.1-0.3, in addition, a surfactant does not need to be added, the process cost is effectively reduced, and the preparation method is suitable for preparing a high-consistency single-crystal or polycrystal positive electrode material and has a wide application prospect. And the method is of great significance in improving the performance of the lithium ion battery positive electrode material and promoting large-scale production of high-energy density batteries.

Description

TECHNICAL FIELD

[0001] The application relates to a nickel-based layered multi-element positive electrode material modification technical field, in particular to a preparation method of multi-element positive electrode material precursor seed crystals with super-narrow particle size distribution. BACKGROUND

[0002] As an important energy storage device in the field of new energy, the performance of a lithium ion battery is directly dependent on the electrochemical characteristics of a positive electrode material, and the performance of the positive electrode material is determined by key parameters such as the morphology, structure and particle size distribution of a precursor. In recent years, with the increasing demand for high-energy-density batteries, ternary positive electrode materials (such as NCM and NCA) have become a research hotspot due to their high specific capacity and cycle stability, but the preparation technology of the precursor still faces significant challenges.

[0003] The particle size distribution of the precursor directly affects the microstructure and electrochemical performance of the positive electrode material. Studies have shown that a wide particle size distribution can lead to uneven porosity between particles during the sintering process, increase the interface resistance and the risk of side reactions, and thus reduce the cycle life and safety of the battery. For example, the precursor prepared by the traditional coprecipitation method often has a wide particle size distribution range and irregular particle morphology due to the uncontrollability of the nucleation and growth stages, which further leads to microcracks and pulverization of the positive electrode material during the charging and discharging process, and the gas production increases significantly. In addition, particles with too small a particle size may accelerate the decomposition of the electrolyte due to the high specific surface area, and particles with too large a particle size may reduce the tap density, limiting the improvement of the energy density of the battery, so it is crucial to develop an efficient and low-cost seed crystal preparation method to precisely control the particle size of the precursor. SUMMARY

[0004] The application provides a preparation method of multi-element positive electrode material precursor seed crystals with super-narrow particle size distribution, which solves the problems of wide particle size distribution and complex process in the traditional method, reduces the manufacturing cost, and provides key technical support for the large-scale production of high-energy-density and long-cycle-life lithium ion batteries.

[0005] The application provides a preparation method of multi-element positive electrode material precursor seed crystals with super-narrow particle size distribution, which solves the problems of wide particle size distribution and complex process in the traditional method, reduces the manufacturing cost, and provides key technical support for the large-scale production of high-energy-density and long-cycle-life lithium ion batteries.

[0006] Step S1, seed nucleation stage: pure water is added to a plurality of small reaction kettles A, air is introduced to control the oxygen content in the non-solution space of the reaction kettle to be 0.005-0.1 mol / L, NaOH solution and nitrogen-containing complexing agent are introduced, the pH value in the reaction kettle is controlled to be 12.5-13.5, the concentration of the nitrogen-containing complexing agent is controlled to be 1.0-2.0 mol / L, the stirring line speed is controlled to be 9-15 m / s, and the solution temperature is controlled to be 40-70 DEG C; after preparation, the flow rate of the introduced manganese sulfate solution, hydrogen peroxide, additive, NaOH solution and nitrogen-containing complexing agent is controlled to be slow, and the reaction is performed for 1-10 h to obtain manganese hydroxide seed crystals, and the seed crystals D 50The solid content of the seed crystal slurry reaches 10-100 g / L, the number of the reactor A is ≥2, the effective volume is 100-1000 L, the molar ratio of the manganese sulfate solution to the hydrogen peroxide is 0.1-3.0, and the molar concentration of the hydrogen peroxide is 1.0-5.0 mol / L;

[0007] In step S2, the seed crystal aging stage, the slurry in the reactor A is added into a medium-sized reactor B for aging treatment, the solid content of the slurry in the reactor B is adjusted to 10-100 g / L, the oxygen content in the non-solution space is 0.01-0.05 mol / L, the pH value is 13.0-13.9, the concentration of the nitrogen-containing complexing agent is 1.0-2.0 mol / L, the stirring line speed is 10-15 m / s, the solution temperature in the reactor is 70-90℃, and the reaction time is 0.5-10 h; the number of the reactor B is ≥1, and the effective volume is 1000-5000 L.

[0008] In step S3, the seed crystal growth stage, the slurry in the reactor B is added into a large-sized reactor C, the solid content of the slurry in the reactor C is adjusted to 50-100 g / L, the oxygen content in the non-solution space is 0.01-0.05 mol / L, the pH value is 13.0-13.9, the concentration of the nitrogen-containing complexing agent is 1.0-2.0 mol / L, the stirring line speed is 12-15 m / s, and the solution temperature in the reactor is 65-70℃; then the flow rate of the multi-element nickel-based sulfate solution, the NaOH solution, the nitrogen-containing complexing agent, and the additive is controlled to be slowly introduced, the reaction conditions are adjusted in stages until the slurry with the target particle size is obtained, and finally the slurry is washed and dried to obtain the multi-element positive electrode material precursor seed crystal; the number of the reactor C is ≥1, the effective volume is 5000-10000 L, the multi-element nickel-based sulfate is XSO4, and X includes one or more of Ni, Co, Mn, Al, Mg, Ti, and Sr.

[0009] Preferably, in step A, the additive is one or more of inorganic sodium salt, inorganic potassium salt, inorganic zinc salt, and inorganic magnesium salt, and the molar concentration is 1.0-2.0 mol / L; and the nitrogen-containing complexing agent is one or a combination of several of ammonia, ammonium sulfite, ammonium bisulfite, ammonium bisulfate, ammonium sulfide, ammonium hydrosulfide, and ammonium thiosulfate.

[0010] Preferably, the molar concentration of the multi-element nickel-based sulfate solution is 1.0-3.0 mol / L, the molar concentration of the manganese sulfate solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-15.0 mol / L, and the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L.

[0011] Preferably, the seed crystal growth stage adjusts the reaction conditions in stages, specifically, in the first stage, the oxygen content in the non-solution space is adjusted to 0.005-0.025 mol / L, the pH value is adjusted to 12.5-13.0, the stirring line speed is adjusted to 10-12 m / s, and the solution temperature in the reactor is adjusted to 60-65℃, until the slurry D 50 reaches 1.0-2.0 μm; in the second stage, the oxygen content in the non-solution space is adjusted to 0.0025-0.01 mol / L, the pH value is adjusted to 12.0-12.5, the concentration of the nitrogen-containing complexing agent is adjusted to 0.5-1.0 mol / L, the stirring line speed is adjusted to 8-10 m / s, and the solution temperature in the reactor is adjusted to 50-60℃, until the slurry D 50 reaches 2.0-3.0 μm; in the third stage, the oxygen content in the non-solution space is adjusted to less than 0.0000001 mol / L, the pH value is adjusted to 11.0-12.0, the concentration of the nitrogen-containing complexing agent is adjusted to 0.1-0.5 mol / L, the stirring line speed is adjusted to 5-8 m / s, and the solution temperature in the reactor is maintained at 50-60℃, until the slurry D 50 reaches 3.0-4.0 μm.

[0012] Preferably, the multi-element positive electrode material precursor seed crystal is uniformly mixed with a lithium-containing compound, and then calcined to obtain a multi-element positive electrode material without cracks; the lithium-containing compound is one or a combination of lithium hydroxide, lithium carbonate, lithium acetate or lithium nitrate.

[0013] Preferably, the calcining comprises the following steps: first, increasing the temperature to 450-550℃ at a rate of 2℃ / min and maintaining the temperature for 4-6 hours; and then increasing the temperature to 700-900℃ at a rate of 2-5℃ / min and maintaining the temperature for 10-15 hours.

[0014] Preferably, the multi-element positive electrode material precursor seed crystal prepared has an ultra-narrow particle size index K of 0.1-0.3, where K=(D 90 -D 10 ) / D 50 , D 50 is the value corresponding to the case that 50% of the particles in the cumulative distribution are smaller than the value, D 10 , D 90 are the values corresponding to the cases that 10% and 90% of the particles in the cumulative distribution are smaller than the values, respectively.

[0015] Advantages:

[0016] (1) The preparation process of the present application does not introduce high-priced surfactants, modifiers and other organic substances, is simple to operate, easy to realize mass production, and reduces the cost of wastewater treatment process.

[0017] (2) The prepared multi-element positive electrode material precursor seed crystal has narrow particle size distribution and good consistency. The seed crystal can be used as a single crystal precursor to obtain a high-compactness single crystal positive electrode material by sintering; the seed crystal can also be used as a polycrystal precursor seed to obtain a polycrystal small-particle positive electrode material with good sphericity and consistency by sintering; and the seed crystal can be further used to prepare a large-particle polycrystal precursor to obtain a corresponding large-particle positive electrode material by sintering.

[0018] (3) In the present application, the seed crystal preparation process is controlled in sections, thereby improving the utilization rate of the seed crystal and reducing the raw material use cost and the manufacturing cost.

[0019] The above description is only a summary of the technical solutions of the embodiments of the present application, in order to more clearly understand the technical means of the embodiments of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0021] Figure 1 It is a layout diagram of a segmented seed crystal reaction kettle;

[0022] Figure 2 It is a SEM diagram of the multi-element positive electrode material precursor seed crystal prepared by the present application;

[0023] Figure 3 It is a SEM diagram of the multi-element positive electrode material precursor seed crystal in the comparative example. DETAILED DESCRIPTION

[0024] In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application; the use herein of terms such as "comprise" and "comprising", and "include" and "including" and any variations thereof, is intended to cover the nature of the features, structures, items, actions, and the like, recited, but not to exclude the presence of one or more additional features, structures, items, actions, and the like.

[0026] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the application. The appearances of the phrase "an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that any of the embodiments described herein can be combined with any of the other embodiments.

[0027] In order to better understand the technical scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings.

[0028] Embodiment 1

[0029] The present application provides a preparation method of a multi-element positive electrode material precursor seed with ultra-narrow particle size distribution, comprising the following steps:

[0030] 1) Step S1, pure water is added into 300L reaction kettles A1 and A2, air is introduced, and the oxygen content in the non-solution space in the reaction kettle is controlled to be 0.1 mol / L; NaOH solution and ammonia water are introduced, and the pH value in the reaction kettle is controlled to be 13.5 and the ammonia value is controlled to be 2.0 mol / L; the stirring line speed of the reaction kettle is 15 m / s, and the solution temperature in the reaction kettle is 70℃. After preparation, 1.5 mol / L MnSO4 solution, 3.0 mol / L hydrogen peroxide solution, 2.0 mol / L Na2SO4 solution, 7.0 mol / L NaOH solution, and 10.0 mol / L ammonia water solution are slowly introduced by controlling the flow rate. At the same time, it is ensured that the oxygen content in the non-solution space in the reaction kettle is 0.1 mol / L, the pH value is 13.5, the ammonia value is 2.0 mol / L, the stirring line speed is 15 m / s, and the solution temperature in the reaction kettle is 70℃; the reaction is carried out for 100 min, and the slurry D in the kettle 50 to 1.0 μm, and the solid content of the slurry reaches 80 g / L;

[0031] 2) Step S2, on the basis of step S1, the slurry in the reaction kettle A1 and A2 is simultaneously added into 2000L reaction kettle B1, and aging treatment is carried out. The solid content of the slurry in the reaction kettle B1 is adjusted to 100g / L, the oxygen content in the non-solution space is 0.05mol / L, the pH value is 13.9, the ammonia value is 2.0mol / L, the stirring line speed is 15m / s, and the solution temperature in the reaction kettle is 90℃; reaction for 10h;

[0032] 3) In the step S3, on the basis of step S2, the slurry in the reaction kettle B1 is simultaneously added into 6000L reaction kettle C1, and the solid content of the slurry in the reaction kettle C1 is adjusted to 100g / L, the oxygen content in the non-solution space is 0.05mol / L, the pH value is 13.9, the ammonia value is 2.0mol / L, the stirring line speed is 15m / s, and the solution temperature in the reaction kettle is 70℃, then by controlling the flow rate, slowly pass in 1.5mol / L of XSO4(M= Ni, Co, Mn, wherein the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05) mixed solution, 7.0mol / L of NaOH solution, 10.0mol / L of ammonia water solution, 2.0mol / L of Na2SO4solution; at the same time, the oxygen content in the non-solution space is gradually reduced to 0.025mol / L, the pH value is gradually reduced to 13.0, the ammonia value is 2.0mol / L, the stirring line speed is gradually reduced to 12m / s, and the solution temperature in the reaction kettle is 65℃, until the slurry D 50 in the kettle reaches 2.0μm; then the oxygen content in the non-solution space is gradually reduced to 0.01mol / L, the pH value is gradually reduced to 12.5, the ammonia value is gradually reduced to 1.0mol / L, the stirring line speed is gradually reduced to 10m / s, and the solution temperature in the reaction kettle is gradually reduced to 60℃, until the slurry D 50 in the kettle reaches 3.0μm; then the oxygen content in the non-solution space is less than 0.0000001mol / L, the pH value is gradually reduced to 12.0, the ammonia value is gradually reduced to 0.5mol / L, the stirring line speed is gradually reduced to 8m / s, and the solution temperature in the reaction kettle is gradually reduced to 60℃, until the slurry D 50 in the kettle reaches 4.0μm; finally, the slurry is washed and dried to obtain Ni 0.90 Co 0.05 Mn 0.05 (OH)2crystal seeds. As Figure 2 shown, the Ni 0.90 Co 0.05 Mn 0.05 (OH)2crystal seeds prepared by the process of the present patent have narrow particle size distribution, good sphericity, and good consistency, which can improve the performance of the subsequent sintered positive electrode material;

[0033] 4) The Ni 0.90 Co0.05 Mn 0.05 (OH)2 precursor seeds were mixed uniformly with LiOH H2O, and then placed in a tube furnace, heated to 500℃ at a heating rate of 5℃ / min, and then kept for 8 hours, and then heated to 775℃ at a heating rate of 3℃ / min, and then kept for 12 hours, to obtain LiNi 0.90 Co 0.05 Mn 0.05 O2 positive electrode material;

[0034] 5) The LiNi 0.90 Co 0.05 Mn 0.05 O2 positive electrode material prepared in the above was modified by water washing and coating, to prepare an electrode sheet, which was assembled into a CR2032 type button cell, and the electrochemical performance was tested, with a first coulombic efficiency of 94.6%, a 0.1C cycle capacity as high as 221mAh / g, and a capacity retention rate as high as 97.8% after 100 0.1C cycles.

[0035] Example 2

[0036] The application provides a preparation method of a multi-element positive electrode material precursor seed with an ultra-narrow particle size distribution, comprising the following steps:

[0037] 1) Step S1, pure water was added into 500L reaction kettles A1 and A2, air was introduced, and the oxygen content in the non-solution space in the reaction kettle was controlled to be 0.05mol / L; NaOH solution and ammonia water were introduced, and the pH value in the reaction kettle was controlled to be 13 and the ammonia value was controlled to be 1.5mol / L; the stirring line speed of the reaction kettle was 13m / s, and the solution temperature in the reaction kettle was 60℃. After preparation, 2.0mol / L MnSO4 solution, 2.0mol / L hydrogen peroxide, 1.5mol / L KCl solution, 5.0mol / L NaOH solution and 10.0mol / L ammonia water were slowly introduced by controlling the flow rate. At the same time, the oxygen content in the non-solution space in the reaction kettle was controlled to be 0.05mol / L, the pH value was controlled to be 13, the ammonia value was controlled to be 1.5mol / L, the stirring line speed was controlled to be 13m / s, and the solution temperature in the reaction kettle was controlled to be 60℃; the reaction was carried out for 80min, and the slurry D 50 to 0.8μm, and the solid content of the slurry reached 60g / L;

[0038] 2) Step S2, on the basis of step S1, the slurries in the reaction kettles A1 and A2 were simultaneously added into a 3000L reaction kettle B1 for aging treatment. The solid content of the slurry in the reaction kettle B1 was adjusted to be 80g / L, the oxygen content in the non-solution space was controlled to be 0.03mol / L, the pH value was controlled to be 13.5, the ammonia value was controlled to be 1.5mol / L, the stirring line speed was controlled to be 13m / s, and the solution temperature in the reaction kettle was controlled to be 80℃; the reaction was carried out for 8h;

[0039] 3) In step S3, based on step S2, the slurry in the reactor B1 is added to the 8000L reactor C1, and the solid content of the slurry in the reactor C1 is adjusted to 80g / L, the oxygen content in the non-solution space is 0.03mol / L, the pH value is 13.5, the ammonia value is 1.5mol / L, the stirring line speed is 13m / s, and the solution temperature in the reactor is 68℃. Then, by controlling the flow rate, 2.0mol / L of the mixed solution of XSO4(M= Ni, Co, Mn, Al, wherein the molar ratio of Ni:Co:Mn:Al is 0.94:0.025:0.025:0.01), 5.0mol / L of NaOH solution, 10.0mol / L of ammonia water solution, and 1.5mol / L of KCl solution are slowly introduced; at the same time, the oxygen content in the non-solution space is gradually reduced to 0.01mol / L, the pH value is gradually reduced to 12.8, the ammonia value is 1.5mol / L, the stirring line speed is gradually reduced to 11m / s, and the solution temperature in the reactor is gradually reduced to 64℃, until the slurry D 50 in the reactor reaches 1.8μm; then the oxygen content in the non-solution space is gradually reduced to 0.005mol / L, the pH value is gradually reduced to 12.3, the ammonia value is gradually reduced to 0.8mol / L, the stirring line speed is gradually reduced to 9m / s, and the solution temperature in the reactor is gradually reduced to 58℃, until the slurry D 50 in the reactor reaches 2.8μm; then the oxygen content in the non-solution space is less than 0.0000001mol / L, the pH value is gradually reduced to 11.6, the ammonia value is gradually reduced to 0.3mol / L, the stirring line speed is gradually reduced to 7m / s, and the solution temperature in the reactor is gradually reduced to 58℃, until the slurry D 50 in the reactor reaches 3.8μm; finally, the slurry is washed and dried to obtain Ni 0.94 Co 0.025 Mn 0.025 Al 0.01 (OH)2crystal seeds with no agglomeration and high sphericity;

[0040] 4) The Ni 0.94 Co 0.025 Mn 0.025 Al 0.01 (OH)2precursor crystal seeds in step 3) are uniformly mixed with LiOH·H2O, and then placed in a tube furnace, heated to 500℃ at a heating rate of 5℃ / min, and then held for 8 hours, and then heated to 775℃ at a heating rate of 3℃ / min, and then held for 12 hours, to obtain LiNi 0.94 Co 0.025 Mn 0.025 Al 0.01 O2positive electrode material;

[0041] 5) The LiNi 0.94 Co0.025 Mn 0.025 Al 0.01 The O2 positive electrode material is washed and modified by coating, then an electrode sheet is prepared, a CR2032 type button cell is assembled, and the electrochemical performance is tested, with a first coulomb efficiency of 94.6%, a 0.1C cycle capacity of up to 221 mAh / g, and a capacity retention rate of up to 97.8% after 100 0.1C cycles;

[0042] 4) the Ni 0.94 Co 0.025 Mn 0.025 Al 0.01 The (OH)2 precursor seed crystal is uniformly mixed with LiOH·H2O, then placed in a tube furnace, heated to 500 DEG C at a heating rate of 5 DEG C / min, and then kept for 8 hours, and then heated to 742 DEG C at a heating rate of 3 DEG C / min, and then kept for 12 hours, to obtain a LiNi 0.94 Co 0.025 Mn 0.025 Al 0.01 O2 positive electrode material;

[0043] 5) the LiNi 0.94 Co 0.025 Mn 0.025 Al 0.01 The O2 positive electrode material is washed and modified by coating, then an electrode sheet is prepared, a CR2032 type button cell is assembled, and the electrochemical performance is tested, with a first coulomb efficiency of 94.8%, a 0.1C cycle capacity of up to 233.7 mAh / g, and a capacity retention rate of up to 98.7% after 100 0.1C cycles.

[0044] Example 3

[0045] The application provides a preparation method of a multi-element positive electrode material precursor seed crystal with an ultra-narrow particle size distribution, comprising the following steps:

[0046] 1) Step S1, pure water was added into 800L reactors A1 and A2, air was introduced, and the oxygen content in the non-solution space in the reactor was controlled at 0.02 mol / L; NaOH solution and ammonia water were introduced, and the pH value in the reactor was controlled at 12.8 and the ammonia value was 1.2 mol / L; the stirring speed of the reactor was 12 m / s, and the solution temperature in the reactor was 65℃. After preparation, 2.5 mol / L MnSO4 solution, 1.0 mol / L hydrogen peroxide solution, 1.0 mol / L ZnSO4 solution, 4.0 mol / L NaOH solution, and 8.0 mol / L ammonia solution were slowly introduced by controlling the flow rate. At the same time, the oxygen content in the non-solution space in the reactor was controlled at 0.02 mol / L, the pH value was controlled at 12.8, the ammonia value was controlled at 1.2 mol / L, the stirring speed was controlled at 12 m / s, and the solution temperature in the reactor was controlled at 65℃. The reaction was carried out for 60 min, and the slurry D 50 in the reactor reached 0.6 μm, and the solid content of the slurry reached 50 g / L;

[0047] 2) Step S2, on the basis of step S1, the slurry in reactors A1 and A2 was simultaneously added into 5000L reactor B1 for aging treatment. The solid content of the slurry in reactor B1 was adjusted to 90 g / L, the oxygen content in the non-solution space was 0.02 mol / L, the pH value was 13.0, the ammonia value was 1.2 mol / L, the stirring speed was 12 m / s, and the solution temperature in the reactor was 78℃. The reaction was carried out for 7 h;

[0048] 3) In step S3, on the basis of step S2, the slurry in reactor B1 was added into 10000L reactor C1, and the solid content of the slurry in reactor C1 was adjusted to 90 g / L, the oxygen content in the non-solution space was 0.02 mol / L, the pH value was 13.2, the ammonia value was 1.2 mol / L, the stirring speed was 12 m / s, and the solution temperature in the reactor was 65℃. Then, 2.5 mol / L XSO4 (M = Ni, Mn, Al, Mg, wherein the molar ratio of Ni:Mn:Al:Mg was 0.96:0.025:0.015:0.01) mixed solution, 5.0 mol / L NaOH solution, 8.0 mol / L ammonia solution, and 1.0 mol / L ZnSO4 solution were slowly introduced by controlling the flow rate. At the same time, the oxygen content in the non-solution space was gradually reduced to 0.006 mol / L, the pH value was gradually reduced to 12.5, the ammonia value was 1.2 mol / L, the stirring speed was gradually reduced to 10 m / s, and the solution temperature in the reactor was gradually reduced to 62℃, until the slurry D 501.5 μm; then the oxygen content in the non-solution space is adjusted to gradually decrease to 0.003 mol / L, the pH value is adjusted to gradually decrease to 12.0, the ammonia value is adjusted to gradually decrease to 0.6 mol / L, the stirring line speed is adjusted to gradually decrease to 8 m / s, and the solution temperature in the reactor is adjusted to gradually decrease to 55°C until the slurry D 50 2.5 μm; then the oxygen content in the non-solution space is adjusted to less than 0.0000001 mol / L, the pH value is adjusted to gradually decrease to 11.4, the ammonia value is adjusted to gradually decrease to 0.2 mol / L, the stirring line speed is adjusted to gradually decrease to 6.5 m / s, and the solution temperature in the reactor is adjusted to gradually decrease to 50°C until the slurry D 50 3.5 μm; finally, the slurry is washed and dried to obtain Ni 0.96 Mn 0.025 Al 0.015 Mg 0.01 (OH)2crystal seeds. The slurry is washed and dried to obtain Ni 0.96 Mn 0.025 Al 0.015 Mg 0.01 (OH)2crystal seeds;

[0049] 4) The Ni 0.96 Mn 0.025 Al 0.015 Mg 0.01 (OH)2precursor crystal seeds prepared in step 3) are uniformly mixed with LiOH H2O, and then placed in a tube furnace, heated to 500°C at a heating rate of 5°C / min, and then held for 7 hours, and then heated to 724°C at a heating rate of 3°C / min, and then held for 15 hours to obtain LiNi 0.96 Mn 0.025 Al 0.015 Mg 0.01 O2cathode material;

[0050] 5) The LiNi 0.96 Mn 0.025 Al 0.0215 Mg 0.01 O2cathode material prepared above is washed with water and modified by coating, to prepare an electrode sheet, which is assembled into a CR2032 type button cell, and the electrochemical performance is tested, with a first coulombic efficiency of 95.7%, a 0.1C cycle capacity of up to 241.7 mAh / g, and a capacity retention rate of up to 98.8% after 100 cycles at 0.1C.

[0051] Comparative Example 1

[0052] 1) Step S1, pure water was added into 300L reaction kettles A1 and A2, NaOH solution, ammonia water was introduced, the pH value in the reaction kettle was controlled to be 13.5, and the ammonia value was 2.0 mol / L; the stirring line speed of the reaction kettle was 15 m / s, and the solution temperature in the reaction kettle was 70℃. After preparation, 1.5 mol / L XSO4 (M=Ni, Co, Mn, wherein the molar ratio of Ni:Co:Mn was 0.90:0.05:0.05) mixed solution, 7.0 mol / L NaOH solution, and 10.0 mol / L ammonia solution were introduced. At the same time, the pH value was 13.5, the ammonia value was 2.0 mol / L, the stirring line speed was 15 m / s, and the solution temperature in the reaction kettle was 70℃; the reaction was carried out for 100 min, and the slurry D 50 in the kettle reached 1.0 μm, and the solid content of the slurry reached 80 g / L.

[0053] 2) Step S2, on the basis of step S1, the slurry in the reaction kettles A1 and A2 was simultaneously added into 2000L reaction kettle B1 for aging treatment. The solid content of the slurry in the reaction kettle B1 was adjusted to reach 100 g / L, the oxygen content in the non-solution space was 0.05 mol / L, the pH value was 13.9, the ammonia value was 2.0 mol / L, the stirring line speed was 15 m / s, and the solution temperature in the reaction kettle was 90℃; the reaction was carried out for 10 h;

[0054] 3) In step S3, on the basis of step S2, the slurry in the reaction kettle B1 was simultaneously added into 6000L reaction kettle C1, and the solid content of the slurry in the reaction kettle C1 was adjusted to reach 100 g / L, the oxygen content in the non-solution space was less than 0.0000001 mol / L, the pH value was 13.9, the ammonia value was 2.0 mol / L, the stirring line speed was 15 m / s, and the solution temperature in the reaction kettle was 70℃. 1.5 mol / L XSO4 mixed solution, 7.0 mol / L NaOH solution, and 10.0 mol / L ammonia solution were introduced; until the slurry D 50 in the kettle reached 4.0 μm; finally, the slurry was washed and dried to obtain Ni 0.90 Co 0.05 Mn 0.05 (OH)2crystal seeds. As shown in Figure 1 , the Ni 0.90 Co 0.05 Mn 0.05 (OH)2crystal seeds prepared by the process of the present patent have narrow particle size distribution, good sphericity, and good consistency, which can improve the performance of the subsequent sintered positive electrode material. As shown in Figure 3 , the Ni 0.90 Co 0.05 Mn 0.05 (OH)2crystal seeds prepared by the conventional process have serious agglomeration, very poor sphericity, and poor consistency, which seriously affects the performance of the subsequent sintered positive electrode material.

[0055] 4) Ni 0.90 Co 0.05 Mn 0.05 The LiNi 0.90 Co 0.05 Mn 0.05 O2 cathode material is obtained.

[0056] 5) The LiNi 0.90 Co 0.05 Mn 0.05 O2 cathode material is washed with water and modified by coating, to prepare an electrode sheet, which is assembled into a CR2032 type button cell, and the electrochemical performance is tested. The first coulombic efficiency is only 85.6%, the 0.1C cycle capacity is only 201.4 mAh / g, and after 100 cycles at 0.1C, the capacity retention rate is only 87.4%.

[0057] The button cell test data of the examples and comparative examples are shown in Tables 1 and 2:

[0058]

[0059] Table 1

[0060] Discharge gravimetric capacity (mAh / g) Example 1 Example 2 Example 3 Comparative Example 1 0.2C / 0.2C, 2.8-4.3v 218.6 231.1 235.3 199.7 0.2C / 0.2C, 2.8-4.5v 222.3 232.8 237.8 201.5 2C / 2C, 2.8-4.3v 217.5 225.4 232.5 193.8 2C / 2C, 2.8-4.5v 218.3 227.1 233.9 195.7 5C / 5C, 2.8-4.3v 212.8 223.9 229.3 190.3 5C / 5C, 2.8-4.5v 215.3 225.8 231.4 192.2

[0061] Table 2

[0062] The multi-element cathode material precursor provided by the application is prepared by controlling the growth of the seed crystal in different reaction kettles in a segmented and fine manner. The seed crystal can be directly washed and dried to obtain a small-particle multi-element precursor, or can be grown in a reaction kettle to obtain a large-particle multi-element precursor.

[0063] First, in the seed crystal nucleation process in the reaction kettle, a small kettle is used as a nucleation carrier, a certain amount of air in the bottom liquid is used as a dispersant, manganese hydroxide is used as a crystal nucleus, and low flow rate, high pH, high speed, high temperature and inorganic salt are used as auxiliary induction and dispersion, so that the seed crystal nucleation process has strong dispersibility and can be uniformly nucleated. The small seed crystal is then aged, which can not only improve the utilization rate of the seed crystal, but also further improve the uniformity of the seed crystal. Finally, the high-precision process control under different particle sizes is controlled in a segmented manner, the seed crystal growth is controlled at a low flow rate, the specific surface area of the seed crystal is controlled at a high ammonia value, and the uniform growth of the seed crystal growth stage is continuously maintained.

[0064] Secondly, the obtained precursor crystal seeds can be directly subjected to back-end washing, drying, packaging and other treatments, used as single crystal precursors, or used as polycrystalline small particle precursors. Moreover, the obtained precursor crystal seeds can be filtered to remove the mother liquor under the protection of nitrogen, and trace amounts of sodium and sulfur can be removed by washing to obtain relatively pure multi-element precursor crystal seed precipitate. Then, the crystal seeds are used as cores to continuously grow in a reaction kettle, and through different high-precision control processes and product index requirements, the desired tap density, specific surface area, sphericity, and morphology of the precursor product can be obtained. The method is simple to operate, has low requirements for production equipment, can be mass-produced, and is high in efficiency.

[0065] To sum up, the preparation process of the application does not introduce high-priced surfactants, modifiers and other organic matters, is simple to operate, easy to realize mass production, and reduces the cost of wastewater treatment process. The multi-element positive electrode material precursor crystal seed prepared by the application has narrow particle size distribution and good consistency. It can be used as a single crystal precursor to obtain high-density single crystal positive electrode material by sintering. It can also be used as a polycrystalline precursor crystal seed to sinter into a polycrystalline small particle positive electrode material with good sphericity and consistency. It can also be used to prepare large particle polycrystalline precursors by continuous growth, and sintered into corresponding large particle positive electrode materials. In the application, the crystal seed preparation process is controlled in sections, which improves the utilization rate of the crystal seeds and reduces the cost of raw materials and manufacturing.

[0066] The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some technical features. These modifications or replacements do not change the essence of the corresponding technical solutions, and do not deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a seed crystal of a multi-element positive electrode material precursor with an ultra-narrow particle size distribution, characterized in that, Comprising the following steps: Step S1, seed nucleation stage: in a plurality of small reaction kettle A is added pure water, into the air control reaction kettle non-solution space oxygen content is 0.005-0.1mol / L, into NaOH solution, nitrogen complexing agent, control reaction kettle pH value is 12.5-13.5, nitrogen complexing agent concentration is 1.0-2.0mol / L, stirring line speed is 9-15m / s, solution temperature is 40-70℃;Ready, control flow rate slowly into manganese sulfate solution, hydrogen peroxide, additives, NaOH solution, nitrogen complexing agent, reaction 1-10h, get manganese hydroxide seed, seed D 50 0.5-1.0μm, seed slurry solid content reaches 10-100g / L;The number of said reaction kettle A is ≥2, the effective volume is 100-1000L, the molar ratio of manganese sulfate solution to hydrogen peroxide is 0.1-3.0, and the molar concentration of hydrogen peroxide is 1.0-5.0mol / L. Step S2, seed aging stage: the slurry in the reactor A is added to the medium-sized reactor B for aging treatment, the solid content of the slurry in the reactor B is adjusted to 10-100 g / L, the oxygen content in the non-solution space is 0.01-0.05 mol / L, the pH value is 13.0-13.9, the concentration of the nitrogen-containing complexing agent is 1.0-2.0 mol / L, the stirring line speed is 10-15 m / s, the solution temperature in the reactor is 70-90℃, and the reaction time is 0.5-10 h; the number of the reactor B is ≥1, and the effective volume is 1000-5000 L; Step S3, seed growth stage: the slurry in the reactor B is added to the large-sized reactor C, the solid content of the slurry in the reactor C is adjusted to 50-100 g / L, the oxygen content in the non-solution space is 0.01-0.05 mol / L, the pH value is 13.0-13.9, the concentration of the nitrogen-containing complexing agent is 1.0-2.0 mol / L, the stirring line speed is 12-15 m / s, and the solution temperature in the reactor is 65-70℃; then the flow rate of the multi-element nickel-based sulfate solution, NaOH solution, nitrogen-containing complexing agent, and additive is slowly controlled to be introduced, the reaction conditions are adjusted in stages until the slurry with the target particle size is obtained, and finally the slurry is washed and dried to obtain the multi-element positive electrode material precursor seed; the number of the reactor C is ≥1, the effective volume is 5000-10000 L, and the multi-element nickel-based sulfate is XSO4, X including one or more of Ni and Co, Mn, Al, Mg, Ti, and Sr.

2. The method according to claim 1, wherein the method is characterized by, In the step A, the additive is one or more of inorganic sodium salt, inorganic potassium salt, inorganic zinc salt, and inorganic magnesium salt, and the molar concentration is 1.0-2.0 mol / L; and the nitrogen-containing complexing agent is one or a combination of several of ammonia, ammonium sulfite, ammonium bisulfite, ammonium bisulfate, ammonium sulfide, ammonium hydrosulfide, and ammonium thiosulfate or ammonium carbonate.

3. The method according to claim 1, wherein the method is characterized by, The molar concentration of the multi-element nickel-based sulfate solution is 1.0-3.0 mol / L, the molar concentration of the manganese sulfate solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-15.0 mol / L, and the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L.

4. The method according to claim 1, wherein the method is characterized by, The seed growth stage adjusts the reaction conditions in stages. In the first stage, the oxygen content in the non-solution space is adjusted to 0.005-0.025 mol / L, the pH value is adjusted to 12.5-13.0, the stirring line speed is adjusted to 10-12 m / s, and the solution temperature in the reactor is adjusted to 60-65℃, until the slurry D 50 reaches 1.0-2.0 μm; in the second stage, the oxygen content in the non-solution space is adjusted to 0.0025-0.01 mol / L, the pH value is adjusted to 12.0-12.5, the concentration of the nitrogen-containing complexing agent is adjusted to 0.5-1.0 mol / L, the stirring line speed is adjusted to 8-10 m / s, and the solution temperature in the reactor is adjusted to 50-60℃, until the slurry D 50 reaches 2.0-3.0 μm; in the third stage, the oxygen content in the non-solution space is adjusted to less than 0.0000001 mol / L, the pH value is adjusted to 11.0-12.0, the concentration of the nitrogen-containing complexing agent is adjusted to 0.1-0.5 mol / L, the stirring line speed is adjusted to 5-8 m / s, and the solution temperature in the reactor is maintained at 50-60℃, until the slurry D 50 reaches 3.0-4.0 μm.

5. The method according to claim 1, wherein the method is characterized by, The multi-element positive electrode material precursor seed is mixed with a lithium-containing compound and then calcined to obtain a multi-element positive electrode material without cracks; the lithium-containing compound is one or a combination of several of lithium hydroxide, lithium carbonate, lithium acetate, or lithium nitrate.

6. The method according to claim 5, wherein the method is characterized by, The calcination comprises the following steps: first, heating at a rate of 2℃ / min to 450-550℃, and keeping the temperature for 4-6 hours; and then heating at a rate of 2-5℃ / min to 700-900℃, and keeping the temperature for 10-15 hours.

7. The method according to claim 1, wherein the method is characterized by, The prepared poly-element positive electrode material precursor seed crystal has an ultra-narrow particle size index K of 0.1-0.3, wherein K=(D 90 -D 10 ) / D 50 , D 50 is a value corresponding to 50% of particles in the cumulative distribution being less than the value, D 10 , D 90 respectively represent values corresponding to 10% and 90% of particles in the cumulative distribution being less than the value.

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