Preparation method of precursor seed crystal of multi-element positive electrode material

Abstract

The invention relates to a preparation method of a precursor seed crystal of a multi-element positive electrode material. The preparation method comprises the following steps: step S1, a preparation stage before seed crystal preparation; s2, a seed crystal nucleation stage; and S3, a seed crystal growth stage. On the basis of a conventional process, in the nucleation period of primary particles of precursor crystal seeds, inorganic sodium salt is used for adjusting the primary particles of the precursor crystal seeds to be thinned and thinned, meanwhile, a high-pH low-ammonia-value process is adopted for further adjusting the thickness of the primary particles of the precursor crystal seeds, and a high-rotating-speed and high-temperature process is matched, so that the dissolution and dispersity of the primary particles are improved; therefore, the agglomeration of the primary particles of the precursor seed crystal is avoided, and the nucleation strong dispersity and non-agglomeration of the primary particles of the seed crystal are effectively controlled and regulated. And through subsequent high-precision process control, the strong dispersity and non-agglomeration of the seed crystal in the growth stage are continuously kept, and finally the multi-element positive electrode material precursor seed crystal which is free of agglomeration and high in sphericity degree is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of nickel-based multi-element positive electrode material modification, and in particular to a method for preparing a multi-element positive electrode material precursor seed. Background Art

[0002] With the rapid development of electric vehicles and portable electronic devices, the market demand for high energy density and long life batteries is increasing. Multi-element materials have become an important choice for improving battery performance due to their high reversible specific capacity and good electrochemical performance. In particular, high nickel multi-element materials can not only significantly improve the energy density of the battery by increasing the proportion of nickel, but also reduce the use of cobalt, thereby reducing the material cost to a certain extent. As a scarce and price-volatile metal, reducing its use is of great significance to the long-term development of the battery industry. High nickel multi-element cathode material precursors, as a key component of multi-element cathode materials, have become a hot topic in current battery material research. Although high nickel multi-element cathode material precursors have many advantages, their preparation process faces many challenges. Multi-element precursors are highly customized standard products of multi-element cathode materials and are key materials for producing multi-element cathodes. The performance of multi-element precursors directly determines the main physical and chemical properties of multi-element cathode materials, such as particle size, element ratio, and impurity content, thereby affecting the core electrochemical properties of lithium batteries, such as consistency, rate performance, energy density, and cycle life. The most common synthesis method of multi-component precursors is the co-precipitation method, which is a mixed solution of nickel, cobalt and manganese salts, which is produced by salt-alkali neutralization reaction in the presence of ammonia as a chelating agent, sodium hydroxide as a precipitant and a nitrogen atmosphere. The core process parameters include salt concentration, alkali concentration, ammonia concentration, the rate at which the reaction liquid is added to the reactor, reaction temperature, pH value, stirring speed, solid content, reaction time, etc. Each parameter will affect the particle size, morphology, element ratio, etc. of the precursor. Therefore, the control accuracy of process conditions is the key to determining the overall performance and stability of the product, and it also best reflects the process level of each company.

[0003] The biggest problem is the preparation of the seed crystals of the high-nickel multi-element cathode material precursor. The seed crystals of the high-nickel multi-element cathode material precursor can be used as single crystal materials or as polycrystalline materials to continue to grow. Therefore, the morphology, sphericity, consistency and other characteristics of the seed crystals directly affect the subsequent cathode material performance. At present, the seed crystals of conventional multi-element cathode material precursors are seriously agglomerated, resulting in poor sphericity, which has a great impact on the performance of the cathode material. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a multi-element positive electrode material precursor seed crystal with no agglomeration and high sphericity. On the basis of conventional processes, during the nucleation of the primary particles of the precursor seed crystal, inorganic sodium salt is used to adjust the primary particles of the precursor seed crystal to be thinner and finer, and a high pH and low ammonia value process is used to further adjust the thickness of the primary particles of the precursor seed crystal, and then a high speed and high temperature process is used to improve the solubility and dispersibility of the primary particles, thereby avoiding the agglomeration of the primary particles of the precursor seed crystal, so as to effectively control and regulate the strong dispersibility and non-agglomeration of the nucleation of the primary particles of the seed crystal. Subsequently, through high-precision process control, the strong dispersibility and non-agglomeration of the seed crystal growth stage are continuously maintained, and finally a multi-element positive electrode material precursor seed crystal with no agglomeration and high sphericity is achieved to solve the problems raised in the above-mentioned background technology.

[0005] A method for preparing a multi-element positive electrode material precursor seed crystal comprises the following steps:

[0006] Step S1, preparation stage before seed crystal preparation;

[0007] Step S2, seed nucleation stage;

[0008] Step S3, seed crystal growth stage.

[0009] As a further preferred embodiment of the present technical solution, in step S1, a certain amount of pure water is added to the reactor, air is introduced, and the oxygen content in the non-solution space in the reactor is regulated to be 0.01-0.05 mol / L; NaOH solution and a nitrogen-containing complexing agent are introduced to control the pH value in the reactor to be 12.5-13.5, and the concentration of the nitrogen-containing complexing agent is 0.05-0.3 mol / L; an inorganic sodium salt solution is introduced to control the concentration of the inorganic sodium salt solution in the reactor to be 1.0-2.0 mol / L; the stirring linear speed of the reactor is 9-15 m / s, and the temperature of the solution in the reactor is 70-80°C; the inorganic sodium salt solution is one or a combination of sodium sulfate solution, sodium nitrate solution, and sodium chloride solution; the nitrogen-containing complexing agent is one or a combination of ammonia water, ammonium sulfite, ammonium bisulfite, ammonium bisulfate, ammonium sulfide, ammonium hydrogen sulfide, ammonium thiosulfate or ammonium carbonate.

[0010] As a further preferred embodiment of the present technical solution, in step S2, after step S1 is ready, air, polybasic nickel-based sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution are introduced; at the same time, it is ensured that: the oxygen content in the non-solution space in the reactor is 0.01-0.05 mol / L, the pH value is 12.5-13.5, the concentration of the nitrogen-containing complexing agent is 0.05-0.3 mol / L, the concentration of the inorganic sodium salt solution is 1.0-2.0 mol / L, the stirring linear speed is 9-15 m / s, and the temperature of the solution in the reactor is 70-80°C; the reaction is carried out for 1-100 min, and the slurry D in the reactor is 50Reach 0.5-1.0μm; the polybasic nickel-based sulfate is XSO4, wherein X must include Ni, and the other elements are one or more of Co, Mn, Al, Mg, Ti, and Sr. The molar concentration of the polybasic nickel-based sulfate solution is 1.0-3.0mol / L, the molar concentration of the NaOH solution is 2.0-7.0mol / L, the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0mol / L, and the molar concentration of the inorganic sodium salt solution is 5.0-10.0mol / L.

[0011] As a further preferred embodiment of the present technical solution, in step S3, on the basis of step S2, the inert gas, the polybasic nickel-based sulfate solution, the NaOH solution, the nitrogen-containing complexing agent, and the inorganic sodium salt solution are introduced and adjusted; the concentration of the nitrogen-containing complexing agent is maintained at 0.05-0.3 mol / L, and the stirring line speed is 9-15 m / s; and at the same time, the oxygen content in the non-solution space in the kettle is gradually reduced to 0.005-0.025 mol / L, the concentration of the inorganic sodium salt solution is 0.5-1.0 mol / L, and the temperature of the solution in the kettle is 65-70°C; until the slurry D in the kettle 50 After that, continue to adjust the amount of inert gas, polybasic nickel sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution; maintain the concentration of nitrogen-containing complexing agent at 0.05-0.3 mol / L, and gradually reduce the stirring line speed to 5-10 m / s, the oxygen content in the non-solution space in the kettle is 0.0025-0.005 mol / L, the concentration of inorganic sodium salt solution is 0.25-0.5 mol / L, and the temperature of the solution in the kettle is 60-65 ° C; until the slurry D in the kettle 50 After that, continue to adjust the amount of inert gas, polybasic nickel sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution; maintain the concentration of nitrogen-containing complexing agent at 0.05-0.3 mol / L, the stirring line speed at 5-10 m / s, and gradually reduce the oxygen content in the non-solution space in the kettle to 0.0005-0.0025 mol / L, the concentration of inorganic sodium salt solution at 0.05-0.25 mol / L, and the temperature of the solution in the kettle at 55-60 ° C; until the slurry D in the kettle 50 Reach 3.0-4.0 μm; finally, wash and dry the slurry to obtain a multi-element positive electrode material precursor seed crystal with no agglomeration and high sphericity;

[0012] D of the slurry in the reactor 50When the size reaches 1.0-2.0μm, 2.0-3.0μm or 3.0-4.0μm, the feeding can be stopped, and the slurry can be washed and dried to obtain a multi-component positive electrode material precursor seed crystal with no agglomeration and high sphericity; the multi-component material precursor seed crystal is evenly mixed with a lithium-containing compound and calcined to obtain a crack-free multi-component positive electrode material, and the lithium-containing compound is one or a combination of lithium hydroxide, lithium carbonate, lithium acetate or lithium nitrate.

[0013] As a further preferred embodiment of the present technical solution, the molar concentration of the polynic nickel-based sulfate solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-7.0 mol / L, the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L, and the molar concentration of the inorganic sodium salt solution is 5.0-10.0 mol / L.

[0014] As a further preferred embodiment of the present technical solution, the calcination comprises the following specific steps: heating to 450-550°C at 2°C / min and keeping warm for 4-6 hours; then heating to 700-900°C at 2-5°C / min and keeping warm for 10-15 hours.

[0015] As a further preferred embodiment of the present technical solution, the sphericity index Φ of the prepared multi-element positive electrode material precursor seed is 1.0-1.6, wherein Φ=Di / Dc, Di is the maximum inscribed sphere radius of the particle, and Dc is the minimum inscribed sphere radius of the same particle.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The multi-element positive electrode material precursor seeding process prepared by the present invention does not introduce relatively expensive substances containing organic molecules, but only uses conventional substances, is simple to operate, and is very easy to achieve production. At the same time, the cost of wastewater treatment process is greatly reduced.

[0018] 2. The multi-element cathode material precursor seed prepared by the present invention has no agglomeration problem, good sphericity and good consistency. It can be used not only as a single crystal precursor, and then sintered into a single crystal cathode material with high compaction; it can also be used as a polycrystalline precursor seed, and sintered into a polycrystalline small-particle cathode material with good sphericity and good consistency; or it can continue to grow to prepare a large-particle polycrystalline precursor, and sintered into a polycrystalline large-particle cathode material with good sphericity and good consistency.

[0019] Other advantages and features of the present invention will be partially reflected in the following description, and partly will be understood by those skilled in the art through research and practice of the present invention. The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are specifically cited below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, a brief introduction will be given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a SEM image of the multi-element positive electrode material precursor seed prepared in the present invention.

[0022] Figure 2 This is the SEM image of the precursor seed crystal of the multi-electrode material in the comparative example. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification, claims and drawings of this application are intended to cover non-exclusive inclusions.

[0025] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0027] Example 1

[0028] 1) Step S1, preparation stage before seed preparation: add pure water to the reactor, introduce air, and adjust the oxygen content in the non-solution space in the reactor to 0.05 mol / L; introduce 10.0 mol / L NaOH solution and 10.0 mol / L ammonia solution, control the pH value in the reactor to 13.5, and the concentration of ammonia to 0.3 mol / L; introduce NaSO4 solution, and control the concentration of NaSO4 solution in the reactor to 2.0 mol / L; the stirring linear speed of the reactor is 12 m / s, and the temperature of the solution in the reactor is 80°C.

[0029] 2) Step S2, seed nucleation stage: After step S1 is prepared, air, 1.5 mol / L XSO4 (M = Ni, Co, Mn, wherein the molar ratio of Ni: Co: Mn is 0.90: 0.05: 0.05) mixed solution, 10.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution are introduced; at the same time, the oxygen content in the non-solution space in the reactor is 0.05 mol / L, the pH value is 13.5, the concentration of ammonia water is 0.3 mol / L, the concentration of NaSO4 solution is 2.0 mol / L, the stirring linear speed is 12 m / s, and the solution temperature in the reactor is 80°C; react for 50 min, and the slurry D in the reactor is 50 Reach 1.0μm.

[0030] 3) Step S3, seed growth stage: on the basis of step S2, introduce and adjust the amount of inert gas, 1.5 mol / L XSO4 solution, 10.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution; maintain the concentration of ammonia solution at 0.3 mol / L and the stirring line speed at 12 m / s; and at the same time gradually reduce the oxygen content in the non-solution space in the kettle to 0.025 mol / L, the concentration of NaSO4 solution to 1.0 mol / L, and the temperature of the solution in the kettle to 70°C; until the slurry D in the kettle 50 After that, continue to adjust the inert gas, 1.5mol / L XSO4 solution, 10.0mol / L NaOH solution, 10.0mol / L ammonia solution, and NaSO4 solution; keep the concentration of ammonia solution at 0.3mol / L, and gradually reduce the stirring speed to 10m / s, the oxygen content in the non-solution space in the kettle to 0.005mol / L, the concentration of NaSO4 solution to 0.5mol / L, and the temperature of the solution in the kettle to 65℃; until the slurry D in the kettle50 The slurry is washed and dried to obtain a Ni spherical material with no agglomeration and high sphericity. 0.90 Co 0.05 Mn 0.05 (OH)2 seed. Figure 1 As shown, the Ni prepared by the process used in this patent 0.90 Co 0.05 Mn 0.05 (OH)2 seed crystals have no agglomeration, good sphericity and consistency, and can improve the performance of the subsequent sintered positive electrode material.

[0031] 4) Take Ni from step 3) 0.90 Co 0.05 Mn 0.05 The (OH)2 precursor seed was mixed with LiOH·H2O and then placed in a tube furnace. The temperature was raised to 500°C at a heating rate of 5°C / min and then kept at this temperature for 7 hours. The temperature was then raised to 770°C at a heating rate of 3°C / min and then kept at this temperature for 12 hours to obtain LiNi 0.90 Co 0.05 Mn 0.05 O2 positive electrode material.

[0032] 5) Using the LiNi prepared above 0.90 Co 0.05 Mn 0.05 After the O2 positive electrode material was washed and coated for modification, the electrode was prepared and assembled into a CR2032 button battery. The electrochemical performance was tested. The first coulombic efficiency was 94%, the 0.1C cycle capacity was as high as 220mAh / g, and after 100 cycles at 0.1C, the capacity retention rate was as high as 98%.

[0033] Example 2

[0034] 1) Step S1, preparation stage before seed preparation: add pure water to the reactor, introduce air, and adjust the oxygen content in the non-solution space in the reactor to 0.03 mol / L; introduce 8.0 mol / L NaOH solution and 10.0 mol / L ammonia solution, control the pH value in the reactor to 13.0, and the concentration of ammonia to 0.2 mol / L; introduce NaSO4 solution, and control the concentration of NaSO4 solution in the reactor to 1.5 mol / L; the stirring linear speed of the reactor is 11 m / s, and the temperature of the solution in the reactor is 75°C.

[0035] 2) Step S2, seed nucleation stage: After step S1 is prepared, air, 2.0 mol / L XSO4 (M = Ni, Co, Mn, Al, wherein the molar ratio of Ni: Co: Mn: Al is 0.94: 0.025: 0.025: 0.01) mixed solution, 8.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution are introduced; at the same time, the oxygen content in the non-solution space in the reactor is 0.03 mol / L, the pH value is 13.0, the concentration of ammonia water is 0.2 mol / L, the concentration of NaSO4 solution is 1.5 mol / L, the stirring linear speed is 11 m / s, and the temperature of the solution in the reactor is 75°C; react for 30 minutes, and the slurry D in the reactor is 50 Reach 0.8μm.

[0036] 3) Step S3, seed growth stage: on the basis of step S2, introduce and adjust the amount of inert gas, 2.0 mol / L XSO4 solution, 8.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution; maintain the concentration of ammonia solution at 0.2 mol / L and the stirring line speed at 11 m / s; and at the same time gradually reduce the oxygen content in the non-solution space in the kettle to 0.015 mol / L, the concentration of NaSO4 solution to 0.8 mol / L, and the temperature of the solution in the kettle to 68°C; until the slurry D in the kettle 50 After that, continue to adjust the inert gas, 2.0mol / L XSO4 solution, 8.0mol / L NaOH solution, 10.0mol / L ammonia solution, and NaSO4 solution; keep the concentration of ammonia solution at 0.2mol / L, and gradually reduce the stirring speed to 9m / s, the oxygen content in the non-solution space in the kettle to 0.003mol / L, the concentration of NaSO4 solution to 0.3mol / L, and the temperature of the solution in the kettle to 63℃; until the slurry D in the kettle 50 The slurry was washed and dried to obtain a Ni spherical material with no agglomeration and high sphericity. 0.94 Co 0.025 Mn 0.025 Al 0.01 (OH)2 seed crystals.

[0037] 4) Take Ni from step 3) 0.94 Co 0.025 Mn 0.025 Al 0.01 The (OH)2 precursor seed was mixed with LiOH·H2O and then placed in a tube furnace. The temperature was raised to 500°C at a heating rate of 5°C / min and then kept at this temperature for 7 hours. The temperature was then raised to 740°C at a heating rate of 3°C / min and then kept at this temperature for 12 hours to obtain LiNi 0.94 Co 0.025 Mn0.025 Al 0.01 O2 positive electrode material.

[0038] 5) Using the LiNi prepared above 0.94 Co 0.025 Mn 0.025 Al 0.01 After the O2 positive electrode material was washed and coated for modification, the electrode was prepared and assembled into a CR2032 button battery. The electrochemical performance was tested. The first coulombic efficiency was 94.5%, the 0.1C cycle capacity was as high as 233mAh / g, and after 100 cycles at 0.1C, the capacity retention rate was as high as 98.3%.

[0039] Example 3

[0040] 1) Step S1, preparation stage before seed preparation: add pure water to the reactor, introduce air, and adjust the oxygen content in the non-solution space in the reactor to 0.01 mol / L; introduce 8.0 mol / L NaOH solution and 10.0 mol / L ammonia solution, control the pH value in the reactor to 12.5, and the concentration of ammonia to 0.1 mol / L; introduce NaSO4 solution, and control the concentration of NaSO4 solution in the reactor to 1.0 mol / L; the stirring linear speed of the reactor is 10 m / s, and the temperature of the solution in the reactor is 70°C.

[0041] 2) Step S2, seed nucleation stage: After step S1 is prepared, air, 2.0 mol / L XSO4 (M = Ni, Co, Mn, Al, wherein the molar ratio of Ni: Co: Mn: Al is 0.96: 0.025: 0.015: 0.01) mixed solution, 8.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution are introduced; at the same time, the oxygen content in the non-solution space in the reactor is 0.01 mol / L, the pH value is 12.5, the concentration of ammonia water is 0.1 mol / L, the concentration of NaSO4 solution is 1.0 mol / L, the stirring linear speed is 10 m / s, and the solution temperature in the reactor is 70°C; react for 30 minutes, and the slurry D in the reactor is 50 Reach 1.0μm.

[0042] 3) Step S3, seed growth stage: on the basis of step S2, introduce and adjust the amount of inert gas, 2.0 mol / L XSO4 solution, 8.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution; maintain the concentration of ammonia solution at 0.1 mol / L and the stirring line speed at 10 m / s; and at the same time gradually reduce the oxygen content in the non-solution space in the kettle to 0.005 mol / L, the concentration of NaSO4 solution to 0.5 mol / L, and the temperature of the solution in the kettle to 65°C; until the slurry D in the kettle 50After that, continue to adjust the inert gas, 2.0mol / L XSO4 solution, 8.0mol / L NaOH solution, 10.0mol / L ammonia solution, and NaSO4 solution; keep the concentration of ammonia solution at 0.1mol / L, and gradually reduce the stirring speed to 8.5m / s, the oxygen content in the non-solution space in the kettle to 0.0025mol / L, the concentration of NaSO4 solution to 0.25mol / L, and the temperature of the solution in the kettle to 60℃; until the slurry D in the kettle 50 After that, continue to adjust the inert gas, 2.0mol / L XSO4 solution, 8.0mol / L NaOH solution, 10.0mol / L ammonia solution, and NaSO4 solution; keep the concentration of ammonia solution at 0.1mol / L, and gradually reduce the stirring speed to 8m / s, the oxygen content in the non-solution space in the kettle to 0.0015mol / L, the concentration of NaSO4 solution to 0.15mol / L, and the temperature of the solution in the kettle to 55℃; until the slurry D in the kettle 50 The slurry is washed and dried to obtain a Ni spherical material with no agglomeration and high sphericity. 0.96 Co 0.025 Mn 0.015 Al 0.01 (OH)2 seed crystals.

[0043] 4) Take Ni from step 3) 0.96 Co 0.025 Mn 0.015 Al 0.01 The (OH)2 precursor seed was mixed with LiOH·H2O and then placed in a tube furnace. The temperature was raised to 500°C at a heating rate of 5°C / min and then kept at this temperature for 7 hours. The temperature was then raised to 720°C at a heating rate of 3°C / min and then kept at this temperature for 12 hours to obtain LiNi 0.96 Co 0.025 Mn 0.015 Al 0.01 O2 positive electrode material.

[0044] 5) Using the LiNi prepared above 0.96 Co 0.025 Mn 0.015 Al 0.01 After the O2 positive electrode material was washed and coated for modification, the electrode was prepared and assembled into a CR2032 button battery. The electrochemical performance was tested. The first coulomb efficiency was 95%, the 0.1C cycle capacity was as high as 241mAh / g, and after 100 cycles at 0.1C, the capacity retention rate was as high as 99%.

[0045] Comparative Example 1

[0046] 1) Step S1, preparatory stage before seed preparation: add pure water to the reactor, introduce inert gas, introduce 10.0 mol / L NaOH solution and 10.0 mol / L ammonia solution, control the pH value in the reactor to be 13.5, and the concentration of ammonia solution to be 0.3 mol / L; the stirring linear speed of the reactor is 12 m / s, and the temperature of the solution in the reactor is 80°C.

[0047] 2) Step S2, seed nucleation stage: After step S1 is prepared, inert gas, 1.5 mol / L XSO4 (M = Ni, Co, Mn, wherein the molar ratio of Ni: Co: Mn is 0.90: 0.05: 0.05) mixed solution, 10.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, NaSO4 solution are introduced; at the same time, the oxygen content in the non-solution space in the reactor is 0.05 mol / L, the pH value is 13.5, the concentration of ammonia water is 0.3 mol / L, the stirring linear speed is 12 m / s, and the solution temperature in the reactor is 80°C; react for 50 min, and the slurry D in the reactor is 50 Reach 1.0μm.

[0048] 3) Step S3, seed growth stage: on the basis of step S2, inert gas, 1.5 mol / L XSO4 solution, 10.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and NaSO4 solution were introduced and adjusted; the concentration of ammonia solution was maintained at 0.3 mol / L, the stirring line speed was 12 m / s; the temperature of the solution in the kettle was 70°C; until the slurry D in the kettle 50 After that, continue to adjust the inert gas, 1.5mol / L XSO4 solution, 10.0mol / L NaOH solution, 10.0mol / L ammonia solution, and NaSO4 solution; keep the concentration of ammonia water at 0.3mol / L, and gradually reduce the stirring speed to 10m / s and the temperature of the solution in the kettle to 65℃; until the slurry D in the kettle 50 The slurry is washed and dried to obtain a Ni spherical material with no agglomeration and high sphericity. 0.90 Co 0.05 Mn 0.05 (OH)2 seed. Figure 2 As shown, the Ni prepared by conventional process 0.90 Co 0.05 Mn 0.05 (OH)2 seed crystals are severely agglomerated, have very poor sphericity and consistency, and seriously affect the performance of the subsequent sintered positive electrode materials.

[0049] 4) Take Ni from step 3) 0.90 Co 0.05 Mn 0.05The (OH)2 precursor seed was mixed with LiOH·H2O and then placed in a tube furnace. The temperature was raised to 500°C at a heating rate of 5°C / min and then kept at this temperature for 7 hours. The temperature was then raised to 770°C at a heating rate of 3°C / min and then kept at this temperature for 12 hours to obtain LiNi 0.90 Co 0.05 Mn 0.05 O2 positive electrode material.

[0050] 5) Using the LiNi prepared above 0.90 Co 0.05 Mn 0.05 After the O2 positive electrode material was washed and coated for modification, the pole piece was prepared and assembled into a CR2032 button battery. The electrochemical performance was tested. The first coulomb efficiency was 86%, the 0.1C cycle capacity could reach 202mAh / g, and after 100 cycles at 0.1C, the capacity retention rate could reach 88%.

[0051] It can be seen from the comparison of multiple embodiments and comparative examples, as shown in Table 1:

[0052]

[0053] Table 1

[0054] The lithium ion battery positive electrode materials A1, A2, A3 prepared according to the above method in the above Examples 1, 2, 3 and Comparative Example 1 and A4 provided in the comparative example are assembled into button cells according to the following method: the positive electrode material, conductive carbon and polyvinylidene fluoride (PVDF) are added to N-methyl-2-pyrrolidone (NMP) in a mass ratio of 92.5:5:2.5, and the mixture is evenly mixed to form a positive electrode slurry, which is then coated on the positive electrode current collector and vacuum dried to form a positive electrode. The lithium sheet is used as the negative electrode and assembled into a 2025 button cell in a glove box.

[0055] The button cell assembled from A1, A2, A3 and A4 was tested using the CT2001A battery testing system of Wuhan Blue Electric Electronics Co., Ltd., as shown in Table 2.

[0056] Discharge capacity (mAh / g) Example 1 Example 2 Example 3 Comparative Example 1 0.2C / 0.2C, 2.8-4.3v 219 230 235 200 0.2C / 0.2C, 2.8-4.5v 222 233 238 202 2C / 2C, 2.8-4.3v 217 225 232 194 2C / 2C,2.8-4.5v 219 227 234 196 5C / 5C,2.8-4.3v 213 224 229 190 5C / 5C,2.8-4.5v 215 226 231 192

[0057] Table 2

[0058] Analysis: The multi-component positive electrode material precursor provided by the present invention is prepared into multi-component precursor seeds through fine control in a reactor. The seeds can be directly washed and dried to obtain small-particle multi-component precursors; or they can be grown in a reactor to obtain large-particle multi-component precursors.

[0059] First, during the reaction process in the reactor, the bottom liquid contains a certain concentration of sodium sulfate solution as an inducer, a certain amount of air as a dispersant, and high pH, ​​high speed, and high temperature as auxiliary induction and dispersion. The beneficial effect of this technology is that in the process of forming nickel-cobalt-manganese multi-element hydroxide seeds from nickel-cobalt-manganese multi-element mixed sulfates, the addition of inducers and air can induce the growth of primary flaky particles of the multi-element precursor, and at the same time, with the assistance of fine control processes such as high pH, ​​high speed, and high temperature, the precursor seeds can be induced to nucleate and grow towards a morphology with strong dispersion, primary flaky shape, and high sphericity, so that the prepared precursor seeds have no agglomeration problem, and further make the precursor seeds have high sphericity, thereby forming highly consistent seeds.

[0060] Secondly, the obtained precursor seed crystals can not only be directly washed, dried, packaged and processed at the back end, and used as single crystal precursors or polycrystalline small particle precursors. Moreover, the obtained precursor seed crystals can be filtered out of the mother liquor under the protection of nitrogen, and then washed to remove trace amounts of sodium and sulfur, so as to obtain a relatively pure multi-component precursor seed crystal precipitate; after that, the above seed crystals are used as nuclei for continuous growth in the reactor, 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 are finally obtained. This method is simple to operate, has low requirements on production equipment, can be mass-produced and is highly efficient.

[0061] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a multi-element positive electrode material precursor seed crystal, characterized in that: The following steps are involved: Step S1, preparation stage before seed crystal preparation; Step S2, seed nucleation stage; Step S3, seed crystal growth stage.

2. The method for preparing a multi-element positive electrode material precursor seed crystal according to claim 1, characterized in that: In the step S1, a certain amount of pure water is added to the reactor, air is introduced, and the oxygen content in the non-solution space in the reactor is regulated to be 0.01-0.05 mol / L; NaOH solution and nitrogen-containing complexing agent are introduced, and the pH value in the reactor is controlled to be 12.5-13.5, and the concentration of the nitrogen-containing complexing agent is 0.05-0.3 mol / L; inorganic sodium salt solution is introduced, and the concentration of the inorganic sodium salt solution in the reactor is controlled to be 1.0-2.0 mol / L; the stirring line speed of the reactor is 9-15 m / s, and the temperature of the solution in the reactor is 70-80° C.; The inorganic sodium salt solution is one or a combination of sodium sulfate solution, sodium nitrate solution and sodium chloride solution; The nitrogen-containing complexing agent is one or a combination of ammonia water, ammonium sulfite, ammonium bisulfite, ammonium bisulfate, ammonium sulfide, ammonium hydrogensulfide, ammonium thiosulfate or ammonium carbonate.

3. The method for preparing a multi-element positive electrode material precursor seed crystal according to claim 1, characterized in that: In step S2, after step S1 is ready, air, polybasic nickel sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution are introduced; at the same time, it is ensured that: the oxygen content in the non-solution space in the reactor is 0.01-0.05 mol / L, the pH value is 12.5-13.5, the concentration of the nitrogen-containing complexing agent is 0.05-0.3 mol / L, the concentration of the inorganic sodium salt solution is 1.0-2.0 mol / L, the stirring line speed is 9-15 m / s, and the temperature of the solution in the reactor is 70-80°C; the reaction is carried out for 1-100 min, and the slurry D in the reactor is 50 Reach 0.5-1.0μm; The polynary nickel-based sulfate is XSO4, wherein X must include Ni, and the other elements are one or more of Co, Mn, Al, Mg, Ti, and Sr. The molar concentration of the polynary nickel-based sulfate solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-7.0 mol / L, the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L, and the molar concentration of the inorganic sodium salt solution is 5.0-10.0 mol / L.

4. The method for preparing a multi-element positive electrode material precursor seed crystal according to claim 1, characterized in that: In step S3, on the basis of step S2, the amount of inert gas, polybasic nickel-based sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution is introduced and adjusted; the concentration of the nitrogen-containing complexing agent is maintained at 0.05-0.3 mol / L, and the stirring linear speed is 9-15 m / s; At the same time, the oxygen content in the non-solution space in the kettle is gradually reduced to 0.005-0.025 mol / L, the concentration of the inorganic sodium salt solution is 0.5-1.0 mol / L, and the temperature of the solution in the kettle is 65-70°C; until the slurry D in the kettle 50 After that, continue to adjust the amount of inert gas, polybasic nickel sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution; maintain the concentration of nitrogen-containing complexing agent at 0.05-0.3 mol / L, and gradually reduce the stirring line speed to 5-10 m / s, the oxygen content in the non-solution space in the kettle is 0.0025-0.005 mol / L, the concentration of inorganic sodium salt solution is 0.25-0.5 mol / L, and the temperature of the solution in the kettle is 60-65 ° C; until the slurry D in the kettle 50 After that, continue to adjust the amount of inert gas, polybasic nickel sulfate solution, NaOH solution, nitrogen-containing complexing agent, and inorganic sodium salt solution; maintain the concentration of nitrogen-containing complexing agent at 0.05-0.3 mol / L, the stirring line speed at 5-10 m / s, and gradually reduce the oxygen content in the non-solution space in the kettle to 0.0005-0.0025 mol / L, the concentration of inorganic sodium salt solution at 0.05-0.25 mol / L, and the temperature of the solution in the kettle at 55-60 ° C; until the slurry D in the kettle 50 Reach 3.0-4.0 μm; finally, wash and dry the slurry to obtain a multi-element positive electrode material precursor seed crystal with no agglomeration and high sphericity; D of the slurry in the reactor 50 When the particle size reaches 1.0-2.0μm, 2.0-3.0μm or 3.0-4.0μm, the feeding can be stopped, and the slurry can be washed and dried to obtain a multinary positive electrode material precursor seed crystal with no agglomeration and high sphericity; the multinary material precursor seed crystal is evenly mixed with a lithium-containing compound and calcined to obtain a crack-free multinary positive electrode material, and the lithium-containing compound is one or a combination of lithium hydroxide, lithium carbonate, lithium acetate or lithium nitrate.

5. The method for preparing a multi-element positive electrode material precursor seed crystal according to claim 1, characterized in that: The molar concentration of the polybasic nickel-based sulfate solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-7.0 mol / L, the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L, and the molar concentration of the inorganic sodium salt solution is 5.0-10.0 mol / L.

6. The method for preparing a multi-element positive electrode material precursor seed crystal according to claim 4, characterized in that: The calcination comprises the following specific steps: heating to 450-550°C at 2°C / min and keeping the temperature for 4-6 hours; then heating to 700-900°C at 2-5°C / min and keeping the temperature for 10-15 hours.

7. The method for preparing a multi-element positive electrode material precursor seed crystal according to claim 1, characterized in that: The sphericity index Φ of the prepared multi-element positive electrode material precursor seed is 1.0-1.6, wherein Φ=Di / Dc, Di is the maximum inscribed sphere radius of the particle, and Dc is the minimum inscribed sphere radius of the same particle.

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